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Sample records for metal coupled folding

  1. Metal ion coupled protein folding and allosteric motions

    Science.gov (United States)

    Wang, Wei

    2014-03-01

    Many proteins need the help of cofactors for their successful folding and functioning. Metal ions, i.e., Zn2+, Ca2+, and Mg2+ etc., are typical biological cofactors. Binding of metal ions can reshape the energy landscapes of proteins, thereby modifying the folding and allosteric motions. For example, such binding may make the intrinsically disordered proteins have funneled energy landscapes, consequently, ensures their spontaneous folding. In addition, the binding may activate certain biological processes by inducing related conformational changes of regulation proteins. However, how the local interactions involving the metal ion binding can induce the global conformational motions of proteins remains elusive. Investigating such question requires multiple models with different details, including quantum mechanics, atomistic models, and coarse grained models. In our recent work, we have been developing such multiscale methods which can reasonably model the metal ion binding induced charge transfer, protonation/deprotonation, and large conformational motions of proteins. With such multiscale model, we elucidated the zinc-binding induced folding mechanism of classical zinc finger and the calcium-binding induced dynamic symmetry breaking in the allosteric motions of calmodulin. In addition, we studied the coupling of folding, calcium binding and allosteric motions of calmodulin domains. In this talk, I will introduce the above progresses on the metal ion coupled protein folding and allosteric motions. We thank the finacial support from NSFC and the 973 project.

  2. Folded MoS2 layers with reduced interlayer coupling

    OpenAIRE

    Castellanos-Gomez, Andres; van der Zant, Herre S. J.; Steele, Gary A.

    2013-01-01

    We study molybdenum disulfide (MoS2) structures generated by folding single- and bilayer MoS2 flakes. We find that this modified layer stacking leads to a decrease in the interlayer coupling and an enhancement of the photoluminescence emission yield. We additionally find that folded single-layer MoS2 structures show a contribution to photoluminescence spectra of both neutral and charged excitons, which is a characteristic feature of single-layer MoS2 that has not been observed in multilayer M...

  3. Five-fold local symmetry in metallic liquids and glasses

    International Nuclear Information System (INIS)

    Li M Z; Li F X; Zhang H P; Peng H L; Hu Y C; Wang W H

    2017-01-01

    The structure of metallic glasses has been a long-standing mystery. Owing to the disordered nature of atomic structures in metallic glasses, it is a great challenge to find a simple structural description, such as periodicity for crystals, for establishing the structure–property relationship in amorphous materials. In this paper, we briefly review the recent developments of the five-fold local symmetry in metallic liquids and glasses and the understanding of the structure–property relationship based on this parameter. Experimental evidence demonstrates that five-fold local symmetry is found to be general in metallic liquids and glasses. Comprehensive molecular dynamics simulations show that the temperature evolution of five-fold local symmetry reflects the structural evolution in glass transition in cooling process, and the structure–property relationship such as relaxation dynamics, dynamic crossover phenomena, glass transition, and mechanical deformation in metallic liquids and glasses can be well understood base on the simple and general structure parameter of five-fold local symmetry. (paper)

  4. Metallic diffraction grating enhanced coupling in whispering gallery resonator.

    Science.gov (United States)

    Zhou, Yanyan; Yu, Xia; Zhang, Haixi; Luan, Feng

    2013-04-08

    For the first time, metallic diffraction grating is investigated to enable efficient coupling in the whispering gallery resonator (WGR). Six-fold field enhancement in the resonator is achieved with respect to their dielectric counter-parts. This higher coupling efficiency is attributed to the surface plasmon excitation which drives the whispering gallery mode along the grating. Fano resonances have been observed in optical reflection. With the metallic grating, single-port end-fire WGR configuration becomes possible - a scheme that has not been demonstrated in any other WGR coupling devices. Hence, it serves as a prototype for portable whispering gallery devices potentially useful in sensing, switching and nonlinear applications.

  5. Heavy metal ions are potent inhibitors of protein folding.

    Science.gov (United States)

    Sharma, Sandeep K; Goloubinoff, Pierre; Christen, Philipp

    2008-07-25

    Environmental and occupational exposure to heavy metals such as cadmium, mercury and lead results in severe health hazards including prenatal and developmental defects. The deleterious effects of heavy metal ions have hitherto been attributed to their interactions with specific, particularly susceptible native proteins. Here, we report an as yet undescribed mode of heavy metal toxicity. Cd2+, Hg2+ and Pb2+ proved to inhibit very efficiently the spontaneous refolding of chemically denatured proteins by forming high-affinity multidentate complexes with thiol and other functional groups (IC(50) in the nanomolar range). With similar efficacy, the heavy metal ions inhibited the chaperone-assisted refolding of chemically denatured and heat-denatured proteins. Thus, the toxic effects of heavy metal ions may result as well from their interaction with the more readily accessible functional groups of proteins in nascent and other non-native form. The toxic scope of heavy metals seems to be substantially larger than assumed so far.

  6. 76 FR 774 - Folding Metal Tables and Chairs From the People's Republic of China: Notice of Extension of Time...

    Science.gov (United States)

    2011-01-06

    ... DEPARTMENT OF COMMERCE International Trade Administration [A-570-868] Folding Metal Tables and... review of the antidumping duty order on folding metal tables and chairs from the People's Republic of China (``PRC''). See Folding Metal Tables and Chairs: Initiation of New Shipper Review, 75 FR 44767...

  7. 76 FR 72903 - Folding Metal Tables and Chairs From the People's Republic of China: Notice of Correction to the...

    Science.gov (United States)

    2011-11-28

    ... International Trade Administration Folding Metal Tables and Chairs From the People's Republic of China: Notice... the antidumping duty order on folding metal tables and chairs from the People's Republic of China...'').'' \\2\\ \\1\\ See Folding Metal Tables and Chairs From the People's Republic of China: Final Results of...

  8. Metal Cations in G-Quadruplex Folding and Stability

    Science.gov (United States)

    Bhattacharyya, Debmalya; Mirihana Arachchilage, Gayan; Basu, Soumitra

    2016-09-01

    This review is focused on the structural and physico-chemical aspects of metal cation coordination to G-Quadruplexes (GQ) and their effects on GQ stability and conformation. G-Quadruplex structures are non-canonical secondary structures formed by both DNA and RNA. G-quadruplexes regulate a wide range of important biochemical processes. Besides the sequence requirements, the coordination of monovalent cations in the GQ is essential for its formation and determines the stability and polymorphism of GQ structures. The nature, location and dynamics of the cation coordination and their impact on the overall GQ stability are dependent on several factors such as the ionic radii, hydration energy and the bonding strength to the O6 of guanines. The intracellular monovalent cation concentration and the localized ion concentrations determine the formation of GQs and can potentially dictate their regulatory roles. A wide range of biochemical and biophysical studies on an array of GQ enabling sequences have generated at a minimum the knowledge base that allows us to often predict the stability of GQs in presence of the physiologically relevant metal ions, however, prediction of conformation of such GQs is still out of the realm.

  9. Visualization of coupled protein folding and binding in bacteria and purification of the heterodimeric complex

    Science.gov (United States)

    Wang, Haoyong; Chong, Shaorong

    2003-01-01

    During overexpression of recombinant proteins in Escherichia coli, misfolded proteins often aggregate and form inclusion bodies. If an aggregation-prone recombinant protein is fused upstream (as an N-terminal fusion) to GFP, aggregation of the recombinant protein domain also leads to misfolding of the downstream GFP domain, resulting in a decrease or loss of fluorescence. We investigated whether the GFP domain could fold correctly if aggregation of the upstream protein domain was prevented in vivo by a coupled protein folding and binding interaction. Such interaction has been previously shown to occur between the E. coli integration host factors and , and between the domains of the general transcriptional coactivator cAMP response element binding protein (CREB)-binding protein and the activator for thyroid hormone and retinoid receptors. In this study, fusion of integration host factor or the CREB-binding protein domain upstream to GFP resulted in aggregation of the fusion protein. Coexpression of their respective partners, on the other hand, allowed soluble expression of the fusion protein and a dramatic increase in fluorescence. The study demonstrated that coupled protein folding and binding could be correlated to GFP fluorescence. A modified miniintein containing an affinity tag was inserted between the upstream protein domain and GFP to allow rapid purification and identification of the heterodimeric complex. The GFP coexpression fusion system may be used to identify novel protein-protein interactions that involve coupled folding and binding or protein partners that can solubilize aggregation-prone recombinant proteins.

  10. Coupled channel folding model description of α scattering from 9Be

    International Nuclear Information System (INIS)

    Roy, S.; Chatterjee, J.M.; Majumdar, H.; Datta, S.K.; Banerjee, S.R.; Chintalapudi, S.N.

    1995-01-01

    Alpha scattering from 9 Be at E α = 65 MeV is described in the coupled channel framework with phenomenological as well as folded potentials. The multipole components of the deformed density of 9 Be are derived from Nilsson model wave functions. Reasonably good agreements are obtained for the angular distributions of 3/2 - (g.s.) and 5/2 - (2.43 MeV) states of the ground state band with folded potentials. The deformation predicted by the model corroborates with that derived from the phenomenological analysis with potentials of different geometries

  11. Coupled channel folding model description of {alpha} scattering from {sup 9}Be

    Energy Technology Data Exchange (ETDEWEB)

    Roy, S.; Chatterjee, J.M.; Majumdar, H. [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Calcutta 700064 (India); Datta, S.K. [Nuclear Science Centre, P.O.10502, New Delhi 110067 (India); Banerjee, S.R. [Variable Energy Cyclotron Centre, 1/AF Bidhannagar, Calcutta 700064 (India); Chintalapudi, S.N. [Inter-University Consortium, Department of Atomic Energy Facilities, Bidhannagar, Calcutta 700064 (India)

    1995-09-01

    Alpha scattering from {sup 9}Be at {ital E}{sub {alpha}}= 65 MeV is described in the coupled channel framework with phenomenological as well as folded potentials. The multipole components of the deformed density of {sup 9}Be are derived from Nilsson model wave functions. Reasonably good agreements are obtained for the angular distributions of 3/2{sup {minus}}(g.s.) and 5/2{sup {minus}}(2.43 MeV) states of the ground state band with folded potentials. The deformation predicted by the model corroborates with that derived from the phenomenological analysis with potentials of different geometries.

  12. Folding-type coupling potentials in the context of the generalized rotation-vibration model

    Science.gov (United States)

    Chamon, L. C.; Morales Botero, D. F.

    2018-03-01

    The generalized rotation-vibration model was proposed in previous works to describe the structure of heavy nuclei. The model was successfully tested in the description of experimental results related to the electron-nucleus elastic and inelastic scattering. In the present work, we consider heavy-ion collisions and assume this model to calculate folding-type coupling potentials for inelastic states, through the corresponding transition densities. As an example, the method is applied to coupled-channel data analyses for the α + 70,72,74,76Ge systems.

  13. Effect of graphite on folded metal occurrence in honed surfaces of grey and compacted cast irons

    Science.gov (United States)

    do Vale, João Luiz; da Silva, Carlos Henrique; Pintaúde, Giuseppe

    2017-09-01

    Grey cast iron (GCI) and compacted graphite iron (CGI) are the most employed materials to manufacture cylinder liners. The use of diamond tools to hone the surfaces resulted in an increase of the so-called folded metal occurrence. This irregularity can reduce the performance of engines and investigations to understand it have been made. In this sense, the current study aims to correlate the variation of graphite and the folded metal occurrence. Different samples of GCI and CGI were extracted directly of engine blocks, resulting in four metallurgical conditions. Topographical analysis was conducted in an optical interferometer and a dedicated routine to count the folded metal was developed using 3D images. Folded metal occurrence can be associated to a specific region of topography and to an increase in the graphite area fraction. Experimental evidences were provided revealing cross-sectional images of grooves using a scanning electron microscope. In addition, the present investigation shows that a larger amount of folded metal was related to the microstructure of thicker walls of compact graphite iron.

  14. Mechanism of Coupled Folding and Binding in the siRNA-PAZ Complex.

    Science.gov (United States)

    Chen, Hai-Feng

    2008-08-01

    The PAZ domain plays a key role in gene silencing pathway. The PAZ domain binds with siRNAs to form the multimeric RNA-induced silencing complex (RISC). RISC identifies mRNAs homologous to the siRNAs and promotes their degradation. It was found that binding with siRNA significantly enhances apo-PAZ folding. However, the mechanism by which folding is coupled to binding is poorly understood. Thus, the coupling relationship between binding and folding is very important for understanding the function of gene silencing. We have performed molecular dynamics (MD) of both bound and apo-PAZ to study the coupling mechanism between binding and folding in the siRNA-PAZ complex. Room-temperature MD simulations suggest that both PAZ and siRNA become more rigid and stable upon siRNA binding. Kinetic analysis of high-temperature MD simulations shows that both bound and apo-PAZ unfold via a two-state process. The unfolding pathways are different between bound and apo-PAZ: the order of helix III and helices I & II unfolding is switched. Furthermore, transition probability was used to determine the transition state ensemble for both bound and apo-PAZ. It was found that the transition state of bound PAZ is more compact than that of apo-PAZ. The predicted Φ-values suggest that the Φ-values of helix III and sheets of β3-β7 for bound PAZ are more native-like than those of apo-PAZ upon the binding of siRNA. The results can help us to understand the mechanism of gene silencing.

  15. Interaction of ATP with acid-denatured cytochrome c via coupled folding-binding mechanism

    International Nuclear Information System (INIS)

    Ahluwalia, Unnati; Deep, Shashank

    2012-01-01

    Highlights: ► Interaction between ATP and cyt c takes place via coupled binding–folding mechanism. ► Binding of ATP to cyt c is endothermic. ► GTP and CTP induce similar level of helicity in acid-denatured cyt c as with ATP. ► Compactness induced by ATP is far greater than ADP or AMP. - Abstract: The non-native conformations of the cytochrome c (cyt c) are believed to play key roles in a number of physiological processes. Nucleotides are supposed to act as allosteric effectors in these processes by regulating structural transitions among different conformations of cyt c. To understand the interaction between acid denatured cytochrome c and nucleotides, spectroscopic and calorimetric techniques were utilized to observe the structural features of the induced conformation and the energetics of interaction of acid denatured cyt c with different nucleotides. Structure induction in the acid denatured cyt c was observed on the addition of the ∼1 mM nucleotide tri-phosphates (ATP/GTP/CTP) at 25 °C, however, not in the presence of 1 mM nucleotide mono and diphosphates. ATP-bound cyt c at pH 2.0 is likely to have a conformation that has intact α-helical domain. However, Met80-Fe(III) axial bond is still ruptured. Observed thermodynamics reflect interaction between nucleotide and cyt c via coupled binding–folding mechanism. DSC data suggest the preferential binding of the ATP to the folded conformation with respect to the acid denatured cyt c. ITC data indicate that the exothermic folding of cyt c was accompanied by endothermic binding of ATP to cyt c.

  16. 77 FR 39680 - Folding Metal Tables and Chairs From the People's Republic of China: Final Results of Antidumping...

    Science.gov (United States)

    2012-07-05

    ... Metal Tables and Chairs From the People's Republic of China: Final Results of Antidumping Duty... review of the antidumping duty order on folding metal tables and chairs from the People's Republic of... ``Final Results of Review'' section below. \\1\\ See Folding Metal Tables and Chairs From the People's...

  17. A new fold-cross metal mesh filter for suppressing side lobe leakage in terahertz region

    Science.gov (United States)

    Lu, Changgui; Qi, Zhengqing; Guo, Wengao; Cui, Yiping

    2018-04-01

    In this paper we propose a new type of fold-cross metal mesh band pass filter, which keeps diffraction side lobe far away from the main transmission peak and shows much better side lobe suppression. Both experimental and theoretical studies are made to analyze the mechanism of side lobe. Compared to the traditional cross filter, the fold-cross filter has a much lower side lobe with almost the same central frequency, bandwidth and highest transmission about 98%. Using the photolithography and electroplating techniques, we experimentally extend the distance between the main peak and diffraction side lobe to larger than 1 THz for the fold-cross filter, which is two times larger than the cross filter while maintaining the main peak transmissions of 89% at 1.25 THz for the two structures. This type of single layer substrate-free fold-cross metal structure shows better design flexibility and structure reliability with the introduction of fold arms for metal mesh band pass filters.

  18. 77 FR 13539 - Folding Metal Tables and Chairs From the People's Republic of China: Preliminary Results of...

    Science.gov (United States)

    2012-03-07

    ... subsequently corrected language in the original revocation.\\4\\ \\1\\ See Antidumping Duty Order: Folding Metal... the Colombia, Indonesia, Philippines, South Africa, Thailand, and Ukraine are countries comparable to...

  19. Earthworm Lumbricus rubellus MT-2: Metal Binding and Protein Folding of a True Cadmium-MT

    Directory of Open Access Journals (Sweden)

    Gregory R. Kowald

    2016-01-01

    Full Text Available Earthworms express, as most animals, metallothioneins (MTs—small, cysteine-rich proteins that bind d10 metal ions (Zn(II, Cd(II, or Cu(I in clusters. Three MT homologues are known for Lumbricus rubellus, the common red earthworm, one of which, wMT-2, is strongly induced by exposure of worms to cadmium. This study concerns composition, metal binding affinity and metal-dependent protein folding of wMT-2 expressed recombinantly and purified in the presence of Cd(II and Zn(II. Crucially, whilst a single Cd7wMT-2 species was isolated from wMT-2-expressing E. coli cultures supplemented with Cd(II, expressions in the presence of Zn(II yielded mixtures. The average affinities of wMT-2 determined for either Cd(II or Zn(II are both within normal ranges for MTs; hence, differential behaviour cannot be explained on the basis of overall affinity. Therefore, the protein folding properties of Cd- and Zn-wMT-2 were compared by 1H NMR spectroscopy. This comparison revealed that the protein fold is better defined in the presence of cadmium than in the presence of zinc. These differences in folding and dynamics may be at the root of the differential behaviour of the cadmium- and zinc-bound protein in vitro, and may ultimately also help in distinguishing zinc and cadmium in the earthworm in vivo.

  20. Improved in Vitro Folding of the Y2 G Protein-Coupled Receptor into Bicelles

    Directory of Open Access Journals (Sweden)

    Peter Schmidt

    2018-01-01

    Full Text Available Prerequisite for structural studies on G protein-coupled receptors is the preparation of highly concentrated, stable, and biologically active receptor samples in milligram amounts of protein. Here, we present an improved protocol for Escherichia coli expression, functional refolding, and reconstitution into bicelles of the human neuropeptide Y receptor type 2 (Y2R for solution and solid-state NMR experiments. The isotopically labeled receptor is expressed in inclusion bodies and purified using SDS. We studied the details of an improved preparation protocol including the in vitro folding of the receptor, e.g., the native disulfide bridge formation, the exchange of the denaturating detergent SDS, and the functional reconstitution into bicelle environments of varying size. Full pharmacological functionality of the Y2R preparation was shown by a ligand affinity of 4 nM and G-protein activation. Further, simple NMR experiments are used to test sample quality in high micromolar concentration.

  1. Metallic flexible coupling service life and failure modes

    Energy Technology Data Exchange (ETDEWEB)

    Paluh, J.H. [Zurn Industries, Inc., Erie, PA (United States)

    1996-01-01

    Metallic disc and diaphragm are the two principle types of nonlubricated couplings used in high-performance turbomachinery. Both transmit torque and accommodate misalignment between turbomachinery equipment shafts. These types of couplings rely on the flexure of metallic membranes to accept angular and axial misalignment. Design differences contribute to reliability and service life calculations. The paper discusses reliability factors, life analysis, and design improvements.

  2. Consequences of Energetic Frustration on the Ligand-Coupled Folding/Dimerization Dynamics of Allosteric Protein S100A12.

    Science.gov (United States)

    Ren, Weitong; Li, Wenfei; Wang, Jun; Zhang, Jian; Wang, Wei

    2017-10-26

    Allosteric proteins are featured by energetic degeneracy of two (or more) functionally relevant conformations, therefore their energy landscapes are often locally frustrated. How such frustration affects the protein folding/binding dynamics is not well understood. Here, by using molecular simulations we study the consequences of local frustration in the dimerization dynamics of allosteric proteins based on a homodimer protein S100A12. Despite of the structural symmetry of the two EF-hand motifs in the three-dimensional structures, the S100A12 homodimer shows allosteric behaviors and local frustration only in half of its structural elements, i.e., the C-terminal EF-hand. We showed that such spatially asymmetric location of frustration leads to asymmetric dimerization pathways, in which the dimerization is dominantly initiated by the interchain binding of the minimally frustrated N-terminal EF-hands, achieving optimal balance between the requirements of rapid conformational switching and interchain assembling to the energy landscapes. We also showed that the local frustration, as represented by the double-basin topography of the energy landscape, gives rise to multiple cross-linked dimerization pathways, in which the dimerization is coupled with the allosteric motions of the C-terminal EF-hands. Binding of metal ions tends to reshape the energy landscape and modulate the dimerization pathways. In addition, by employing the frustratometer method, we showed that the highly frustrated residue-pairs in the C-terminal EF-hand are partially unfolded during the conformational transitions of the native homodimer, leading to lowing of free energy barrier. Our results revealed tight interplay between the local frustration of the energy landscape and the dimerization dynamics for allosteric proteins.

  3. Rapid measurement of residual dipolar couplings for fast fold elucidation of proteins

    Energy Technology Data Exchange (ETDEWEB)

    Rasia, Rodolfo M. [Jean-Pierre Ebel CNRS/CEA/UJF, Institut de Biologie Structurale (France); Lescop, Ewen [CNRS, Institut de Chimie des Substances Naturelles (France); Palatnik, Javier F. [Universidad Nacional de Rosario, Instituto de Biologia Molecular y Celular de Rosario, Facultad de Ciencias Bioquimicas y Farmaceuticas (Argentina); Boisbouvier, Jerome, E-mail: jerome.boisbouvier@ibs.fr; Brutscher, Bernhard, E-mail: Bernhard.brutscher@ibs.fr [Jean-Pierre Ebel CNRS/CEA/UJF, Institut de Biologie Structurale (France)

    2011-11-15

    It has been demonstrated that protein folds can be determined using appropriate computational protocols with NMR chemical shifts as the sole source of experimental restraints. While such approaches are very promising they still suffer from low convergence resulting in long computation times to achieve accurate results. Here we present a suite of time- and sensitivity optimized NMR experiments for rapid measurement of up to six RDCs per residue. Including such an RDC data set, measured in less than 24 h on a single aligned protein sample, greatly improves convergence of the Rosetta-NMR protocol, allowing for overnight fold calculation of small proteins. We demonstrate the performance of our fast fold calculation approach for ubiquitin as a test case, and for two RNA-binding domains of the plant protein HYL1. Structure calculations based on simulated RDC data highlight the importance of an accurate and precise set of several complementary RDCs as additional input restraints for high-quality de novo structure determination.

  4. Rapid measurement of residual dipolar couplings for fast fold elucidation of proteins

    International Nuclear Information System (INIS)

    Rasia, Rodolfo M.; Lescop, Ewen; Palatnik, Javier F.; Boisbouvier, Jérôme; Brutscher, Bernhard

    2011-01-01

    It has been demonstrated that protein folds can be determined using appropriate computational protocols with NMR chemical shifts as the sole source of experimental restraints. While such approaches are very promising they still suffer from low convergence resulting in long computation times to achieve accurate results. Here we present a suite of time- and sensitivity optimized NMR experiments for rapid measurement of up to six RDCs per residue. Including such an RDC data set, measured in less than 24 h on a single aligned protein sample, greatly improves convergence of the Rosetta-NMR protocol, allowing for overnight fold calculation of small proteins. We demonstrate the performance of our fast fold calculation approach for ubiquitin as a test case, and for two RNA-binding domains of the plant protein HYL1. Structure calculations based on simulated RDC data highlight the importance of an accurate and precise set of several complementary RDCs as additional input restraints for high-quality de novo structure determination.

  5. Several hundred-fold enhanced fluorescence from single fluorophores assembled on silver nanoparticle-dielectric-metal substrate.

    Science.gov (United States)

    Ray, Krishanu; Badugu, Ramachandram; Szmacinski, Henryk; Lakowicz, Joseph R

    2015-10-18

    We observed over 400-fold enhanced fluorescence from single Cy5 molecules assembled on multilayer silver nanoparticle-dielectric-metal (PDM) substrate. This substantial enhancement is due to the near-field enhanced excitation, emission, and interaction of Cy5 with plasmonic nanostructures. Experimental observation is supported by finite-element method calculations.

  6. [H(+)-coupled heavy metal transport in plants].

    Science.gov (United States)

    Migocka, Magdalena; Nowojska, Ewa; Kłobus, Grazyna

    2007-01-01

    It has been recently well documented that metal transport systems play a crucial role in the uptake, distribution and detoxification of heavy metals throughout the plant. A range of gene families that are likely to be involved in essential and non-essential metal transport has been now identified and their plasma membrane and/or tonoplast localization in plant cells has been recently confirmed. These include the primary metal transporters, using ATP as the source of energy and H(+)-coupling transporters, utilizing the electrochemical gradient previously generated by plasma membrane and tonoplast proton pumps. As the presence of nucleotide binding domains in the protein sequence may indicate its ATP-hydrolytic activity, it is more difficult to determine the H(+)-coupling activity of protein on the base of its structure. Thus, the H(+)-coupling activity of protein may be only proved by functional analysis of the protein. In this work, we briefly review the structure, regulation and function of the metal transporters operating as H(+)/metal cotransporters.

  7. Observation and analysis of in vivo vocal fold tissue instabilities produced by nonlinear source-filter coupling: a case study.

    Science.gov (United States)

    Zañartu, Matías; Mehta, Daryush D; Ho, Julio C; Wodicka, George R; Hillman, Robert E

    2011-01-01

    Different source-related factors can lead to vocal fold instabilities and bifurcations referred to as voice breaks. Nonlinear coupling in phonation suggests that changes in acoustic loading can also be responsible for this unstable behavior. However, no in vivo visualization of tissue motion during these acoustically induced instabilities has been reported. Simultaneous recordings of laryngeal high-speed videoendoscopy, acoustics, aerodynamics, electroglottography, and neck skin acceleration are obtained from a participant consistently exhibiting voice breaks during pitch glide maneuvers. Results suggest that acoustically induced and source-induced instabilities can be distinguished at the tissue level. Differences in vibratory patterns are described through kymography and phonovibrography; measures of glottal area, open/speed quotient, and amplitude/phase asymmetry; and empirical orthogonal function decomposition. Acoustically induced tissue instabilities appear abruptly and exhibit irregular vocal fold motion after the bifurcation point, whereas source-induced ones show a smoother transition. These observations are also reflected in the acoustic and acceleration signals. Added aperiodicity is observed after the acoustically induced break, and harmonic changes appear prior to the bifurcation for the source-induced break. Both types of breaks appear to be subcritical bifurcations due to the presence of hysteresis and amplitude changes after the frequency jumps. These results are consistent with previous studies and the nonlinear source-filter coupling theory.

  8. Observation and analysis of in vivo vocal fold tissue instabilities produced by nonlinear source-filter coupling: A case studya

    Science.gov (United States)

    Zañartu, Matías; Mehta, Daryush D.; Ho, Julio C.; Wodicka, George R.; Hillman, Robert E.

    2011-01-01

    Different source-related factors can lead to vocal fold instabilities and bifurcations referred to as voice breaks. Nonlinear coupling in phonation suggests that changes in acoustic loading can also be responsible for this unstable behavior. However, no in vivo visualization of tissue motion during these acoustically induced instabilities has been reported. Simultaneous recordings of laryngeal high-speed videoendoscopy, acoustics, aerodynamics, electroglottography, and neck skin acceleration are obtained from a participant consistently exhibiting voice breaks during pitch glide maneuvers. Results suggest that acoustically induced and source-induced instabilities can be distinguished at the tissue level. Differences in vibratory patterns are described through kymography and phonovibrography; measures of glottal area, open∕speed quotient, and amplitude∕phase asymmetry; and empirical orthogonal function decomposition. Acoustically induced tissue instabilities appear abruptly and exhibit irregular vocal fold motion after the bifurcation point, whereas source-induced ones show a smoother transition. These observations are also reflected in the acoustic and acceleration signals. Added aperiodicity is observed after the acoustically induced break, and harmonic changes appear prior to the bifurcation for the source-induced break. Both types of breaks appear to be subcritical bifurcations due to the presence of hysteresis and amplitude changes after the frequency jumps. These results are consistent with previous studies and the nonlinear source-filter coupling theory. PMID:21303014

  9. Metal-free oxidative coupling of thiols to disulfides using ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 123; Issue 4. Metal-free oxidative coupling of thiols to disulfides using guanidinium nitrate or nitro urea in the presence of silica sulfuric acid. Arash Ghorbani-Choghamarani Mohsen Nikoorazm Hamid Goudarziafshar Alireza Shokr Hosein Almasi. Volume 123 Issue 4 ...

  10. The static characteristics of a torsionally flexible metal coupling

    Directory of Open Access Journals (Sweden)

    Krzysztof FILIPOWICZ

    2008-01-01

    Full Text Available The paper presents a description of test stands and the methodology ofdetermining the static characteristics of a metal coupling of high torsional flexibility. In addition, the paper presents preliminary tests results which enable to determine the above characteristics.

  11. Hillslope-channel coupling in a steep Hawaiian catchment accelerates erosion rates over 100-fold

    Science.gov (United States)

    Stock, J. D.; Hanshaw, M. N.; Rosener, M.; Schmidt, K. M.; Brooks, B. A.; Tribble, G.; Jacobi, J.

    2009-12-01

    season. During Fall storms, sediment concentration is often 10X higher at a given stage. During intense Fall storms, we measured erosion rates using erosion pins (1.0 cm/a), suspended sediment flux (1.5 cm/a) and repeat tripod LiDAR (1.7 cm/a). These rates are at least 100-fold greater than the long-term lowering rate of 0.13 mm/a. A sediment budget constructed by extrapolating hillslope lowering rates to the portions of the catchments mapped as overland flow hotspots predicts a total yearly flux of ~ 6500 t, in agreement with the measured total of ~6200 t. A decadal record illustrates that rainfall intensities sufficient to generate overland flow occur for at least 8-10 hours every year, coincident with 1-3 large storm events. We hypothesize that high lowering rates reflect a combination of long-duration overland flow events, and availability of weathered soils that can be entrained by thin flows. It appears that the generation of loose, seasonally weathered silt is a 1st order control on the amount of sediment exported to the reef. If climate change increases storm frequency or duration, or decreases vegetation cover, sediment loading rates to the reef here could increase dramatically.

  12. Role of non-native electrostatic interactions in the coupled folding and binding of PUMA with Mcl-1

    Science.gov (United States)

    Chu, Wen-Ting; Clarke, Jane; Shammas, Sarah L.; Wang, Jin

    2017-01-01

    PUMA, which belongs to the BH3-only protein family, is an intrinsically disordered protein (IDP). It binds to its cellular partner Mcl-1 through its BH3 motif, which folds upon binding into an α helix. We have applied a structure-based coarse-grained model, with an explicit Debye—Hückel charge model, to probe the importance of electrostatic interactions both in the early and the later stages of this model coupled folding and binding process. This model was carefully calibrated with the experimental data on helical content and affinity, and shown to be consistent with previously published experimental data on binding rate changes with respect to ionic strength. We find that intramolecular electrostatic interactions influence the unbound states of PUMA only marginally. Our results further suggest that intermolecular electrostatic interactions, and in particular non-native electrostatic interactions, are involved in formation of the initial encounter complex. We are able to reveal the binding mechanism in more detail than is possible using experimental data alone however, and in particular we uncover the role of non-native electrostatic interactions. We highlight the potential importance of such electrostatic interactions for describing the binding reactions of IDPs. Such approaches could be used to provide predictions for the results of mutational studies. PMID:28369057

  13. Electronically tunable extraordinary optical transmission in graphene plasmonic ribbons coupled to subwavelength metallic slit arrays.

    Science.gov (United States)

    Kim, Seyoon; Jang, Min Seok; Brar, Victor W; Tolstova, Yulia; Mauser, Kelly W; Atwater, Harry A

    2016-08-08

    Subwavelength metallic slit arrays have been shown to exhibit extraordinary optical transmission, whereby tunnelling surface plasmonic waves constructively interfere to create large forward light propagation. The intricate balancing needed for this interference to occur allows for resonant transmission to be highly sensitive to changes in the environment. Here we demonstrate that extraordinary optical transmission resonance can be coupled to electrostatically tunable graphene plasmonic ribbons to create electrostatic modulation of mid-infrared light. Absorption in graphene plasmonic ribbons situated inside metallic slits can efficiently block the coupling channel for resonant transmission, leading to a suppression of transmission. Full-wave simulations predict a transmission modulation of 95.7% via this mechanism. Experimental measurements reveal a modulation efficiency of 28.6% in transmission at 1,397 cm(-1), corresponding to a 2.67-fold improvement over transmission without a metallic slit array. This work paves the way for enhancing light modulation in graphene plasmonics by employing noble metal plasmonic structures.

  14. Electron-phonon coupling of the actinide metals

    DEFF Research Database (Denmark)

    Skriver, H. L.; Mertig, I.

    1985-01-01

    The authors have estimated the strength of the electron-phonon coupling in Fr and Ra plus the light actinides Ac through Pu. The underlying self-consistent band-structure calculations were performed by the scalar relativistic linear-muffin-tin-orbital method including l quantum numbers s through g......-phonon parameter λ is found to attain its maximum value in Ac, and they predict a transition temperature of 9K for this metal. In the light actinides Th through Pu, λ is found to be of order 0.4 and within a factor of 2 of experiments which is also the accuracy found in studies of the transition metals...

  15. Tribological researches of polimer-metal couples in environments

    Directory of Open Access Journals (Sweden)

    R. Kaczyński

    2010-01-01

    Full Text Available In the paper the results of experimental researches carried out for polymer strengthened carbon fibres-metal couple were presented. The binary scheme of surface layer’s wear in microarea was assumed.The attempt of kinetic’s analysis between matrix and filler with taking into consideration percentage share was carried out. The experiment were done using tribological model such as: probe-pin and antiprobe-disk. Qualitative and quantitative dependences of tribological couples in water and oil environment were determined.

  16. Kinetic model for the coupling between allosteric transitions in GroEL and substrate protein folding and aggregation.

    Science.gov (United States)

    Tehver, Riina; Thirumalai, D

    2008-04-04

    The bacterial chaperonin GroEL and the co-chaperonin GroES assist in the folding of a number of structurally unrelated substrate proteins (SPs). In the absence of chaperonins, SP folds by the kinetic partitioning mechanism (KPM), according to which a fraction of unfolded molecules reaches the native state directly, while the remaining fraction gets trapped in a potentially aggregation-prone misfolded state. During the catalytic reaction cycle, GroEL undergoes a series of allosteric transitions (TR-->R"-->T) triggered by SP capture, ATP binding and hydrolysis, and GroES binding. We developed a general kinetic model that takes into account the coupling between the rates of the allosteric transitions and the folding and aggregation of the SP. Our model, in which the GroEL allosteric rates and SP-dependent folding and aggregation rates are independently varied without prior assumption, quantitatively fits the GroEL concentration-dependent data on the yield of native ribulose bisphosphate carboxylase/oxygenase (Rubisco) as a function of time. The extracted kinetic parameters for the GroEL reaction cycle are consistent with the available values from independent experiments. In addition, we also obtained physically reasonable parameters for the kinetic steps in the reaction cycle that are difficult to measure. If experimental values for GroEL allosteric rates are used, the time-dependent changes in native-state yield at eight GroEL concentrations can be quantitatively fit using only three SP-dependent parameters. The model predicts that the differences in the efficiencies (as measured by yields of the native state) of GroEL, single-ring mutant (SR1), and variants of SR1, in the rescue of mitochondrial malate dehydrogenase, citrate synthase, and Rubisco, are related to the large variations in the allosteric transition rates. We also show that GroEL/S mutants that efficiently fold one SP at the expense of all others are due to a decrease in the rate of a key step in the

  17. Diabatic Molecular Orbitals, Potential Energies, and Potential Energy Surface Couplings by the 4-fold Way for Photodissociation of Phenol.

    Science.gov (United States)

    Xu, Xuefei; Yang, Ke R; Truhlar, Donald G

    2013-08-13

    Complete-active-space self-consistent-field (CASSCF) calculations provide useful reference wave functions for configuration interaction or perturbation theory calculations of excited-state potential energy surfaces including dynamical electron correlation. However, the canonical molecular orbitals (MOs) of CASSCF calculations usually have mixed character in regions of strong interaction of two or more electronic states; therefore, they are unsuitable for diabatization using the configurational uniformity approach. Here, CASSCF diabatic MOs for phenol have been obtained by the 4-fold way, and comparison to the CASSCF canonical MOs shows that they are much smoother. Using these smooth CASSCF diabatic MOs, we performed direct diabatization calculations for the three low-lying states ((1)ππ, (1)ππ*, and (1)πσ*) and their diabatic (scalar) couplings at the dynamically correlated multiconfiguration quasidegenerate perturbation theory (MC-QDPT) level. We present calculations along the O-H stretching and C-C-O-H torsion coordinates for the nonadiabatic photodissociation of phenol to the phenoxyl radical and hydrogen atom. The seams of (1)ππ*/(1)πσ* and (1)ππ/(1)πσ* diabatic crossings are plotted as functions of these coordinates. We also present diabatization calculations for displacements along the out-of-plane ring distortion modes 16a and 16b of the phenyl group. The dominant coupling modes of the two conical intersections ((1)ππ*/(1)πσ* and (1)ππ/(1)πσ*) are discussed. The present diabatization method is confirmed to be valid even for significantly distorted ring structures by diabatization calculations along a reaction path connecting the planar equilibrium geometry of phenol to its strongly distorted prefulvenic form. The present work provides insight into the mode specificity of phenol photodissociation and shows that diabatization at the MC-QDPT level employing CASSCF diabatic MOs can be a good starting point for multidimensional dynamics

  18. A Summary of Coupled, Uncoupled, and Hybrid Tectonic Models for the Yakima Fold Belt--Topical Report

    Energy Technology Data Exchange (ETDEWEB)

    Chamness, Michele A.; Winsor, Kelsey; Unwin, Stephen D.

    2012-08-01

    This document is one in a series of topical reports compiled by the Pacific Northwest National Laboratory to summarize technical information on selected topics important to the performance of a probabilistic seismic hazard analysis of the Hanford Site. The purpose of this report is to summarize the range of opinions and supporting information expressed by the expert community regarding whether a coupled or uncoupled model, or a combination of both, best represents structures in the Yakima Fold Belt. This issue was assessed to have a high level of contention with up to moderate potential for impact on the hazard estimate. This report defines the alternative conceptual models relevant to this technical issue and the arguments and data that support those models. It provides a brief description of the technical issue and principal uncertainties; a general overview on the nature of the technical issue, along with alternative conceptual models, supporting arguments and information, and uncertainties; and finally, suggests some possible approaches for reducing uncertainties regarding this issue.

  19. A highly efficient surface plasmon polaritons excitation achieved with a metal-coupled metal-insulator-metal waveguide

    Directory of Open Access Journals (Sweden)

    Hongyan Yang

    2014-12-01

    Full Text Available We propose a novel metal-coupled metal-insulator-metal (MC-MIM waveguide which can achieve a highly efficient surface plasmon polaritons (SPPs excitation. The MC-MIM waveguide is formed by inserting a thin metal film in the insulator of an MIM. The introduction of the metal film, functioning as an SPPs coupler, provides a space for the interaction between SPPs and a confined electromagnetic field of the intermediate metal surface, which makes energy change and phase transfer in the metal-dielectric interface, due to the joint action of incomplete electrostatic shielding effect and SPPs coupling. Impacts of the metal film with different materials and various thickness on SPPs excitation are investigated. It is shown that the highest efficient SPPs excitation is obtained when the gold film thickness is 60 nm. The effect of refractive index of upper and lower symmetric dielectric layer on SPPs excitation is also discussed. The result shows that the decay value of refractive index is 0.3. Our results indicate that this proposed MC-MIM waveguide may offer great potential in designing a new SPPs source.

  20. Fully-Coupled Metallic Fuel Performance Simulations using BISON

    Energy Technology Data Exchange (ETDEWEB)

    Galloway, Jack D. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Unal, Cetin [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-08-27

    This document is a set of slides intended to accompany a talk at a meeting. The first topic taken up is zirconium redistribution. The rod edge Zr increase is evidently due to the Soret term and temperature gradient. Then metallic fission gas release modeling is considered. Based on a GRSIS/FEAST model, the approach of generating fission gas in the fuel matrix is described. A sensitivity study on parameters is presented, including sodium bond & diffusion coefficient sensitivity along with dt sensitivity. Finally, results of some coupled simulations are shown, with ideas about future work.

  1. Electron-phonon coupling in the rare-earth metals

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt; Mertig, I.

    1990-01-01

    We have estimated the strength of the mass enhancement of the conduction electrons due to electron-phonon interaction in the rare metals Sc, Y, and La–Lu. The underlying self-consistent energy bands were obtained by means of the scalar relativistic linear-muffin-tin-orbital method, and the electron......-phonon parameters were calculated within the Gaspari-Gyorffy formulation. For the heavier rare earths Gd–Tm spin polarization was included both in the band-structure calculations and in the treatment of the electron-phonon coupling to take into account the spin splitting of the conduction electrons induced by the 4...

  2. Optical Properties and Biological Applications of Electromagnetically Coupled Metal Nanoparticles

    Science.gov (United States)

    Sheikholeslami, Sassan Nathan

    The optical properties of metallic particles change dramatically as the size shrinks to the nanoscale. The familiar mirror-like sheen of bulk metals is replaced by the bright, sharp, colorful plasmonic resonances of nanoparticles. The resonances of plasmonic metal nanoparticles are highly tunable throughout the visible spectrum, depending on the size, shape, local dielectric environment, and proximity to other optical resonances. Fundamental and applied research in the nanoscience community in the past few decades has sought to understand and exploit these phenomena for biological applications. In this work, discrete nanoparticle assemblies were produced through biomolecular interactions and studied at the single particle level with darkfield spectroscopy. Pairs of gold nanoparticles tethered by DNA were utilized as molecular rulers to study the dynamics of DNA bending by the restriction enzyme EcoRV. These results substantiated that nanoparticle rulers, deemed "plasmon rulers", could measure the dynamics of single biomolecules with high throughput, long lifetime, and high temporal resolution. To extend these concepts for live cell studies, a plasmon ruler comprised of peptide-linked gold nanoparticle satellites around a core particle was synthesized and utilized to optically follow cell signaling pathways in vivo at the single molecule level. The signal provided by these plasmon rulers allowed continuous observation of caspase-3 activation at the single molecule level in living cells for over 2 hours, unambiguously identifying early stage activation of caspase-3 in apoptotic cells. In the last section of this dissertation, an experimental and theoretical study of electomagnetic coupling in asymmetric metal nanoparticle dimers is presented. A "heterodimer" composed of a silver particle and a gold particle is observed to have a novel coupling between a plasmon mode (free electron oscillations) and an inter-band absorption process (bound electron transitions). The

  3. Enhanced Electron-Phonon Coupling at Metal Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Plummer, Ward E.

    2010-08-04

    The Born-Oppenheimer approximation (BOA) decouples electronic from nuclear motion, providing a focal point for most quantum mechanics textbooks. However, a multitude of important chemical, physical and biological phenomena are driven by violations of this approximation. Vibronic interactions are a necessary ingredient in any process that makes or breaks a covalent bond, for example, conventional catalysis or enzymatically delivered biological reactions. Metastable phenomena associated with defects and dopants in semiconductors, oxides, and glasses entail violation of the BOA. Charge exchange in inorganic polymers, organic slats and biological systems involves charge- induced distortions of the local structure. A classic example is conventional superconductivity, which is driven by the electron-lattice interaction. High-resolution angle-resolved photoemission experiments are yielding new insight into the microscopic origin of electron-phonon coupling (EPC) in anisotropic two-dimensional systems. Our recent surface phonon measurement on the surface of a high-Tc material clearly indicates an important momentum dependent EPC in these materials. In the last few years we have shifted our research focus from solely looking at electron phonon coupling to examining the structure/functionality relationship at the surface of complex transition metal compounds. The investigation on electron phonon coupling has allowed us to move to systems where there is coupling between the lattice, the electrons and the spin.

  4. Controlling plasmon coupling in biomolecule-linked metal nanoparticle assemblies

    Science.gov (United States)

    Sebba, David S.

    with DNA control of interparticle separation. Plasmon coupling is investigated also in binary metal systems. A new method for forming stable oligonucleotide-silver conjugates is presented, and controlled plasmon coupling is observed in reconfigurable core-satellite assemblies composed of 20 nm silver satellites linked to a 50 nm gold core by DNA tethers. Reconfiguration of the DNA linkers from a compact to an extended state results in decreased plasmon coupling and a blue-shift of the gold core plasmon resonance, similar to the response observed in analogous structures formed with gold satellites. Simulations of structures composed of gold and silver cores and satellites are performed to determine how the optical properties of binary metal assemblies may differ from those composed of a single metal. It appears that gold plasmons are systematically red shifted by silver particles, whereas plasmons supported by silver particles appear differentially sensitive to gold particles according to whether the silver particle is in a core position or a satellite shell. Next, the plasmonic properties of immobilized binary nanoparticle assemblies that incorporate a single strongly scattering component that acts as a template for assembly of weakly scattering plasmonic particles are investigated. Assemblies are composed of a streptavidin-coated gold "core" nanoparticle and BSA-biotin-coated gold or silver "satellite" particles. Through correlation of measured and simulated spectra, the dependence of assembly optical properties upon satellite coverage and satellite orientation about the core is addressed. It appears that plasmon coupling in gold core-gold satellite structures depends upon satellite orientation about the core and can manifest as either peak shifting or peak splitting, while the gold plasmon response to silver satellite assembly appears to be independent of satellite orientation. Finally, binary coupling is studied in one-dimensional particle pairs and three

  5. Strange metals at finite 't Hooft coupling

    Energy Technology Data Exchange (ETDEWEB)

    Fadafan, Kazem Bitaghsir [Shahrood University of Technology, Physics Department, P.O. Box 3619995161, Shahrood (Iran, Islamic Republic of)

    2013-01-15

    In this paper, we consider the AdS-Schwarzschild black hole in light-cone coordinates which exhibits non-relativistic z=2 Schrodinger symmetry. Then, we use the AdS/CFT correspondence to investigate the effect of finite-coupling corrections to two important properties of the strange metals which are the Ohmic resistivity and the inverse Hall angle. It is shown that the Ohmic resistivity and inverse Hall angle are linearly and quadratically temperature dependent in the case of R{sup 4} corrections, respectively, while in the case of Gauss-Bonnet gravity, we find that the inverse Hall angle is quadratically temperature dependent and the Ohmic conductivity can never be linearly temperature dependent. (orig.)

  6. Fold-related-fracturing at the Livingstone River anticline (AB; Canada) by coupling field surveying and numerical modelling

    Science.gov (United States)

    Humair, Florian; Epard, Jean-Luc; Bauville, Arthur; Jaboyedoff, Michel; Pana, Dinu; Kaus, Boris; Schmalholz, Stefan

    2016-04-01

    The interpretation of fold-related joints and faults is of primary importance in terms of fluids prospection (e.g. water, oil, gas, C02) since anticlines are potential structural trap while fracturing can strongly influence the storage capacity as well as the migration pathways. Located at the front of the Foothills of the Rocky Mountains in Alberta (Canada), the Livingstone Range (LRA) is analogous to hydrocarbon reservoir that occur elsewhere in the Foothills (Cooley et al., 2011). The Livingstone Range fold system is related to the development of the Livingstone thrust that cuts around 1000m up-section from a regional decollement in the Palliser Formation (Devonian) to another in the Fernie Formation (Jurassic). Our study focuses on the detailed structural investigation of the Livingstone River anticline (northern part of the LRA). It aims at characterizing the anticline geometry as well as the fracturing pattern (orientation, mode, infilling, spacing, trace length, density, and cross-cutting relationships) in order to propose a kinematic interpretation of the fold-related fracturing genesis. The study area is investigated at different scales by combining field surveys with remote sensing (HR-Digital Elevation Model, Ground-based LiDAR, Gigapixel photography) and thin-sections analyses. In a second step we performed finite difference 3D numerical simulations in order to compute the evolution of local principal stress orientation during folding. We compared the fracture (or plastic bands) distribution in the field with 1) a dynamic numerical model of detachment folding; and 2) an instantaneous numerical model based on the final fold geometry. Cooley, M.A., Price, R.A., Dixon, J.M., Kyser, T.K. 2011. Along-strike variations and internal details of chevron-style flexural slip thrust-propagation folds within the southern Livingstone Range anticlinorium, a paleo-hydrocarbon reservoir in southern Alberta Foothills, Canada. AAPG bulletin, 95 (11), 1821-1849.

  7. Conical reflection of light during free-space coupling into a symmetrical metal-cladding waveguide.

    Science.gov (United States)

    Zheng, Yuanlin; Cao, Zhuangqi; Chen, Xianfeng

    2013-09-01

    Novel conical reflection of light by a thick three-layered metal-clad optical waveguide is observed. A symmetrical metal-cladding optical waveguide is used, which exhibits extraordinary conical reflection during free-space coupling of light to the waveguide. The phenomenon is attributed to the leakage of excited ultrahigh-order guided modes and their inter- and intramode coupling interaction.

  8. Coupling effects in bilayer thick metal films perforated with rectangular nanohole arrays

    Directory of Open Access Journals (Sweden)

    Li Yuan

    2013-09-01

    Full Text Available The coupling effects in bilayer thick metal (silver films perforated with rectangular nanohole arrays are investigated using the finite-difference time-domain technique. Many interesting light phenomena are observed as the distance between the metal rectangular nanohole arrays varies. Coupling effects are found to play very important roles on the optical and electronic properties of bilayer metal rectangular nanohole arrays: antisymmetric coupling between surface plasmon polaritons near the top and bottom film plane, and antisymmetric coupling between localized surface plasmon resonances near the two long sides of the rectangular hole, are probably excited in each layer of bilayer metal rectangular nanohole arrays; antisymmetric and symmetric magnetic coupling probably occur between the metal rectangular nanohole arrays.

  9. Cascaded plasmon-plasmon coupling mediated energy transfer across stratified metal-dielectric nanostructures.

    Science.gov (United States)

    Golmakaniyoon, Sepideh; Hernandez-Martinez, Pedro Ludwig; Demir, Hilmi Volkan; Sun, Xiao Wei

    2016-10-04

    Surface plasmon (SP) coupling has been successfully applied to nonradiative energy transfer via exciton-plasmon-exciton coupling in conventionally sandwiched donor-metal film-acceptor configurations. However, these structures lack the desired efficiency and suffer poor photoemission due to the high energy loss. Here, we show that the cascaded exciton-plasmon-plasmon-exciton coupling in stratified architecture enables an efficient energy transfer mechanism. The overlaps of the surface plasmon modes at the metal-dielectric and dielectric-metal interfaces allow for strong cross-coupling in comparison with the single metal film configuration. The proposed architecture has been demonstrated through the analytical modeling and numerical simulation of an oscillating dipole near the stratified nanostructure of metal-dielectric-metal-acceptor. Consistent with theoretical and numerical results, experimental measurements confirm at least 50% plasmon resonance energy transfer enhancement in the donor-metal-dielectric-metal-acceptor compared to the donor-metal-acceptor structure. Cascaded plasmon-plasmon coupling enables record high efficiency for exciton transfer through metallic structures.

  10. Extreme Folding

    Science.gov (United States)

    Demaine, Erik

    2012-02-01

    Our understanding of the mathematics and algorithms behind paper folding, and geometric folding in general, has increased dramatically over the past several years. These developments have found a surprisingly broad range of applications. In the art of origami, it has helped spur the technical origami revolution. In engineering and science, it has helped solve problems in areas such as manufacturing, robotics, graphics, and protein folding. On the recreational side, it has led to new kinds of folding puzzles and magic. I will give an overview of the mathematics and algorithms of folding, with a focus on new mathematics and sculpture.

  11. Spin-orbit coupling and proximity effects in metallic carbon nanotubes

    NARCIS (Netherlands)

    Chudzinski, Piotr

    2015-01-01

    We study the spin-orbit coupling in metallic carbon nanotubes (CNTs) within the many-body Tomonaga-Luttinger liquid framework. For a well-defined subclass of metallic CNTs, that contains both achiral zigzag as well as a subset of chiral tubes, an effective low-energy field theory description is

  12. Effects of quantum coupling on the performance of metal-oxide ...

    Indian Academy of Sciences (India)

    performance. It suggests that the quantum coupling effect should be considered for the performance of a ballistic MOSFET due to the high injection velocity of the channel electron. Keywords. Quantum coupling; metal-oxide-semiconductor field transistors. PACS Nos 85.30.De; 85.30.Tv; 73.40.Gk; 73.40.Qv. 1. Introduction.

  13. Analysis of four toxic metals in a single rice seed by matrix solid phase dispersion -inductively coupled plasma mass spectrometry

    Science.gov (United States)

    He, Xiufen; Chen, Lixia; Chen, Xin; Yu, Huamei; Peng, Lixu; Han, Bingjun

    2016-12-01

    Toxic metals in rice pose great risks to human health. Metal bioaccumulation in rice grains is a criterion of breeding. Rice breeding requires a sensitive method to determine metal content in single rice grains to assist the variety selection. In the present study, four toxic metals of arsenic (As), cadmium (Cd), chromium (Cr) and lead (Pb) in a single rice grain were determined by a simple and rapid method. The developed method is based on matrix solid phase dispersion using multi-wall carbon nanotubes (MWCNTs) as dispersing agent and analyzed by inductively coupled plasma mass spectrometry. The experimental parameters were systematically investigated. The limits of detection (LOD) were 5.0, 0.6, 10 and 2.1 ng g-1 for As, Cd, Cr, and Pb, respectively, with relative standard deviations (n = 6) of rice samples analyzed by this method agreed well with those obtained by the standard microwave digestion. The amount of sample required was reduced approximately 100 fold in comparison with the microwave digestion. The method has a high application potential for other sample matrices and elements with high sensitivity and sample throughput.

  14. PRODUCT DEVELOPMENT PROCESS APPLIED OF FLEXIBLE METALLIC MEMBRANE COUPLING DESIGN

    Directory of Open Access Journals (Sweden)

    DOBRE Daniel

    2014-07-01

    model is created by computer to provide the validation of the features and the performance of the structure. It is revealed that the study of flexible couplings based on elastic deformations is of great theoretical and practical importance today.

  15. Improvement of heavy metal stress and toxicity assays by coupling a transgenic reporter in a mutant nematode strain

    Energy Technology Data Exchange (ETDEWEB)

    Chu, K.-W. [Department of Biology, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China); Chan, Shirley K.W. [Atmospheric, Marine and Coastal Environment Program, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China); Chow, King L. [Department of Biology, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China) and Atmospheric, Marine and Coastal Environment Program, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China)]. E-mail: bokchow@ust.hk

    2005-09-30

    Previous studies have demonstrated that wild type Caenorhabditis elegans displays high sensitivity to heavy metals in a lethality test at a level comparable to that of other bioindicator organisms. Taking advantage of the genetics of this model organism, we have tested a number of mutant strains for enhanced sensitivity in heavy metal induced lethality and stress response. These mutants are defective in genes controlling dauer formation, longevity or response to reactive oxygen species (ROS). Among the tested mutants, a double mutant daf-16 unc-75 strain was identified to have superior sensitivity. It has a 6-, 3- and 2-fold increase in sensitivity to cadmium, copper and zinc, respectively, as compared with that of wild type animals. When a fluorescent reporter transgene was coupled with this double mutant for stress detection, a 10-fold enhancement of sensitivity to cadmium over the wild type strain was observed. These transgenic animals, superior to most of the model organisms currently used in bioassays for environmental pollutants, offer a fast and economic approach to reveal the bioavailability of toxic substance in field samples. This study also demonstrates that combination of genetic mutations and transgenesis is a viable approach to identify sensitive indicator animals for environmental monitoring.

  16. Crystal Structure of the PAC1R Extracellular Domain Unifies a Consensus Fold for Hormone Recognition by Class B G-Protein Coupled Receptors

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Shiva; Pioszak, Augen; Zhang, Chenghai; Swaminathan, Kunchithapadam; Xu, H. Eric (Van Andel); (NU Singapore)

    2012-02-21

    Pituitary adenylate cyclase activating polypeptide (PACAP) is a member of the PACAP/glucagon family of peptide hormones, which controls many physiological functions in the immune, nervous, endocrine, and muscular systems. It activates adenylate cyclase by binding to its receptor, PAC1R, a member of class B G-protein coupled receptors (GPCR). Crystal structures of a number of Class B GPCR extracellular domains (ECD) bound to their respective peptide hormones have revealed a consensus mechanism of hormone binding. However, the mechanism of how PACAP binds to its receptor remains controversial as an NMR structure of the PAC1R ECD/PACAP complex reveals a different topology of the ECD and a distinct mode of ligand recognition. Here we report a 1.9 {angstrom} crystal structure of the PAC1R ECD, which adopts the same fold as commonly observed for other members of Class B GPCR. Binding studies and cell-based assays with alanine-scanned peptides and mutated receptor support a model that PAC1R uses the same conserved fold of Class B GPCR ECD for PACAP binding, thus unifying the consensus mechanism of hormone binding for this family of receptors.

  17. Crystal structure of the PAC1R extracellular domain unifies a consensus fold for hormone recognition by class B G-protein coupled receptors.

    Science.gov (United States)

    Kumar, Shiva; Pioszak, Augen; Zhang, Chenghai; Swaminathan, Kunchithapadam; Xu, H Eric

    2011-01-01

    Pituitary adenylate cyclase activating polypeptide (PACAP) is a member of the PACAP/glucagon family of peptide hormones, which controls many physiological functions in the immune, nervous, endocrine, and muscular systems. It activates adenylate cyclase by binding to its receptor, PAC1R, a member of class B G-protein coupled receptors (GPCR). Crystal structures of a number of Class B GPCR extracellular domains (ECD) bound to their respective peptide hormones have revealed a consensus mechanism of hormone binding. However, the mechanism of how PACAP binds to its receptor remains controversial as an NMR structure of the PAC1R ECD/PACAP complex reveals a different topology of the ECD and a distinct mode of ligand recognition. Here we report a 1.9 Å crystal structure of the PAC1R ECD, which adopts the same fold as commonly observed for other members of Class B GPCR. Binding studies and cell-based assays with alanine-scanned peptides and mutated receptor support a model that PAC1R uses the same conserved fold of Class B GPCR ECD for PACAP binding, thus unifying the consensus mechanism of hormone binding for this family of receptors.

  18. Crystal structure of the PAC1R extracellular domain unifies a consensus fold for hormone recognition by class B G-protein coupled receptors.

    Directory of Open Access Journals (Sweden)

    Shiva Kumar

    Full Text Available Pituitary adenylate cyclase activating polypeptide (PACAP is a member of the PACAP/glucagon family of peptide hormones, which controls many physiological functions in the immune, nervous, endocrine, and muscular systems. It activates adenylate cyclase by binding to its receptor, PAC1R, a member of class B G-protein coupled receptors (GPCR. Crystal structures of a number of Class B GPCR extracellular domains (ECD bound to their respective peptide hormones have revealed a consensus mechanism of hormone binding. However, the mechanism of how PACAP binds to its receptor remains controversial as an NMR structure of the PAC1R ECD/PACAP complex reveals a different topology of the ECD and a distinct mode of ligand recognition. Here we report a 1.9 Å crystal structure of the PAC1R ECD, which adopts the same fold as commonly observed for other members of Class B GPCR. Binding studies and cell-based assays with alanine-scanned peptides and mutated receptor support a model that PAC1R uses the same conserved fold of Class B GPCR ECD for PACAP binding, thus unifying the consensus mechanism of hormone binding for this family of receptors.

  19. Ferromagnetism and interlayer exchange coupling in thin metallic films

    Energy Technology Data Exchange (ETDEWEB)

    Kienert, Jochen

    2008-07-15

    This thesis is concerned with the ferromagnetic Kondo lattice (s-d,s-f) model for film geometry. The spin-fermion interaction of this model refers to substances in which localized spins interact with mobile charge carriers like in (dilute) magnetic semiconductors, manganites, or rare-earth compounds. The carrier-mediated, indirect interaction between the localized spins comprises the long-range, oscillatory RKKY exchange interaction in the weak-coupling case and the short-range doubleexchange interaction for strong spin-fermion coupling. Both limits are recovered in this work by mapping the problem onto an effective Heisenberg model. The influence of reduced translational symmetry on the effective exchange interaction and on the magnetic properties of the ferromagnetic Kondo lattice model is investigated. Curie temperatures are obtained for different parameter constellations. The consequences of charge transfer and of lattice relaxation on the magnetic stability at the surface are considered. Since the effective exchange integrals are closely related to the electronic structure in terms of the density of states and of the kinetic energy, the discussion is based on the modifications of these quantities in the dimensionally-reduced case. The important role of spin waves for thin film and surface magnetism is demonstrated. Interlayer exchange coupling represents a particularly interesting and important manifestation of the indirect interaction among localized magnetic moments. The coupling between monatomic layers in thin films is studied in the framework of an RKKY approach. It is decisively determined by the type of in-plane and perpendicular dispersion of the charge carriers and is strongly suppressed above a critical value of the Fermi energy. Finally, the temperature-dependent magnetic stability of thin interlayer-coupled films is addressed and the conditions for a temperature-driven magnetic reorientation transition are discussed. (orig.)

  20. Electron-phonon coupling of the actinide metals

    DEFF Research Database (Denmark)

    Skriver, H. L.; Mertig, I.

    1985-01-01

    The authors have estimated the strength of the electron-phonon coupling in Fr and Ra plus the light actinides Ac through Pu. The underlying self-consistent band-structure calculations were performed by the scalar relativistic linear-muffin-tin-orbital method including l quantum numbers s through g......, and the electron-phonon parameters were obtained within the rigid-atomic-sphere approximation. The electron-phonon coupling in Fr through Th is found to be dominated by pd and df scattering and in Pa through Pu by pd and fg scattering. At the equilibrium volumes and as a function of atomic number, the electron...... be related to the changeover from an s-to- d to an s-to-f electronic transition and a related change in the topology of the Fermi surface...

  1. Metal binding is critical for the folding and function of laminin binding protein, Lmb of Streptococcus agalactiae.

    Directory of Open Access Journals (Sweden)

    Preethi Ragunathan

    Full Text Available Lmb is a 34 kDa laminin binding surface adhesin of Streptococcus agalactiae. The structure of Lmb reported by us recently has shown that it consists of a metal binding crevice, in which a zinc ion is coordinated to three highly conserved histidines. To elucidate the structural and functional significance of the metal ion in Lmb, these histidines have been mutated to alanine and single, double and triple mutants were generated. These mutations resulted in insolubility of the protein and revealed altered secondary and tertiary structures, as evidenced by circular dichroism and fluorescence spectroscopy studies. The mutations also significantly decreased the binding affinity of Lmb to laminin, implicating the role played by the metal binding residues in maintaining the correct conformation of the protein for its binding to laminin. A highly disordered loop, proposed to be crucial for metal acquisition in homologous structures, was deleted in Lmb by mutation (ΔLmb and its crystal structure was solved at 2.6 Å. The ΔLmb structure was identical to the native Lmb structure with a bound zinc ion and exhibited laminin binding activity similar to wild type protein, suggesting that the loop might not have an important role in metal acquisition or adhesion in Lmb. Targeted mutations of histidine residues confirmed the importance of the zinc binding crevice for the structure and function of the Lmb adhesin.

  2. Metal-free carbon-carbon bond-forming reductive coupling between boronic acids and tosylhydrazones.

    Science.gov (United States)

    Barluenga, José; Tomás-Gamasa, María; Aznar, Fernando; Valdés, Carlos

    2009-09-01

    The formation of carbon-carbon bonds is a fundamental transformation in organic synthesis. In spite of the myriad methods available, advantageous methodologies in terms of selectivity, availability of starting materials, operational simplicity, functional-group tolerance, environmental sustainability and economy are in constant demand. In this context, the development of new cross-coupling reactions that use catalysts based on inexpensive and non-toxic metals is attracting increasing attention. Similarly, efficient processes that do not require a metal catalyst are of extraordinary interest. Here, we report a new and efficient metal-free carbon-carbon bond-forming coupling between tosylhydrazones and boronic acids. This reaction is very general and functional-group tolerant. As the required tosylhydrazones are easily generated from carbonyl compounds, it can be seen as a reductive coupling of carbonyls, a process of high synthetic relevance that requires several steps using other methodologies.

  3. 76 FR 35832 - Folding Metal Tables and Chairs From the People's Republic of China: Preliminary Results of...

    Science.gov (United States)

    2011-06-20

    ... Roller Bearings and Parts Thereof, Finished or Unfinished, from the People's Republic of China: Final... E-Z Up Inc.'s (``E-Z Up'') Instant Work Bench is not included within the scope of the antidumping... producer PT Lion Metal Works Tbk's (``Lion'') for the fiscal year 2009 represent the better data compared...

  4. 76 FR 2883 - Folding Metal Tables and Chairs From the People's Republic of China: Final Results of 2007-2008...

    Science.gov (United States)

    2011-01-18

    ... metal tables are the following: Lawn furniture; Trays commonly referred to as ``TV trays;'' Side tables... advertised differently than chairs covered by the scope of the order. On October 4, 2007, the Department... requirements, when imposed, shall remain in effect until further notice. Notification to Interested Parties...

  5. Orientation-Dependent Exciton-Plasmon Coupling in Embedded Organic/Metal Nanowire Heterostructures.

    Science.gov (United States)

    Li, Yong Jun; Hong, Yan; Peng, Qian; Yao, Jiannian; Zhao, Yong Sheng

    2017-10-24

    The excitation of surface plasmons by optical emitters based on exciton-plasmon coupling is important for plasmonic devices with active optical properties. It has been theoretically demonstrated that the orientation of exciton dipole can significantly influence the coupling strength, yet systematic study of the coupling process in nanostructures is still hindered by the lack of proper material systems. In this work, we have experimentally investigated the orientation-dependent exciton-plasmon coupling in a rationally designed organic/metal nanowire heterostructure system. The heterostructures were prepared by inserting silver nanowires into crystalline organic waveguides during the self-assembly of dye molecules. Structures with different exciton orientations exhibited varying coupling efficiencies. The near-field exciton-plasmon coupling facilitates the design of nanophotonic devices based on the directional surface plasmon polariton propagations.

  6. Ultra-low coupling loss fully-etched apodized grating coupler with bonded metal mirror

    DEFF Research Database (Denmark)

    Ding, Yunhong; Peucheret, Christophe; Ou, Haiyan

    2014-01-01

    A fully etched apodized grating coupler with bonded metal mirror is designed and demonstrated on the silicon-on-insulator platform, showing an ultra-low coupling loss of only 1.25 dB with 3 dB bandwidth of 69 nm.......A fully etched apodized grating coupler with bonded metal mirror is designed and demonstrated on the silicon-on-insulator platform, showing an ultra-low coupling loss of only 1.25 dB with 3 dB bandwidth of 69 nm....

  7. Engineering of metal-clad optical nanocavity to optimize coupling with integrated waveguides

    OpenAIRE

    Kim, Myung-Ki; Li, Zheng; Huang, Kun; Going, Ryan; Wu, Ming C.; Choo, Hyuck

    2013-01-01

    We propose a cladding engineering method that flexibly modifies the radiation patterns and rates of metal-clad nanoscale optical cavity. Optimally adjusting the cladding symmetry of the metal-clad nanoscale optical cavity modifies the modal symmetry and produces highly directional radiation that leads to 90% coupling efficiency into an integrated waveguide. In addition, the radiation rate of the cavity mode can be matched to its absorption rate by adjusting the thickness of the bottom-claddin...

  8. Electronically tunable extraordinary optical transmission in graphene plasmonic ribbons coupled to subwavelength metallic slit arrays

    OpenAIRE

    Kim, Seyoon; Jang, Min Seok; Brar, Victor W.; Tolstova, Yulia; Mauser, Kelly W.; Atwater, Harry A.

    2016-01-01

    Subwavelength metallic slit arrays have been shown to exhibit extraordinary optical transmission, whereby tunnelling surface plasmonic waves constructively interfere to create large forward light propagation. The intricate balancing needed for this interference to occur allows for resonant transmission to be highly sensitive to changes in the environment. Here we demonstrate that extraordinary optical transmission resonance can be coupled to electrostatically tunable graphene plasmonic ribbon...

  9. Polyimide modified with metal coupling agent for adhesion application

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Mei-Hui, E-mail: tsaimh@ncut.edu.t [Department of Chemical and Materials Engineering, National Chin-Yi University of Technology, Taichung 411, Taiwan (China); Lin, Yin-Kai [Department of Chemical and Materials Engineering, National Chin-Yi University of Technology, Taichung 411, Taiwan (China); Chang, Chi-Jung [Department of Chemical Engineering, Feng Chia University, Taichung 407, Taiwan (China); Chiang, Pei-Chun [Department of Materials Science and Engineering, Mingdao University, Changhua 523, Taiwan (China); Yeh, Jui-Ming [Department of Chemistry and Center for Nanotechnology, Chung-Yuan Christian University, Chung Li 320, Taiwan (China); Chiu, Wei-Ming; Huang, Shih-Liang; Ni, Sheng-Chung [Department of Chemical and Materials Engineering, National Chin-Yi University of Technology, Taichung 411, Taiwan (China)

    2009-07-01

    Polyimide hybrid metal oxide thin films used on flexible print circuit boards are prepared by the in situ sol-gel process. The precursor, poly (amic acid), containing 2,2'-bis[4-(4-aminophenoxy) phenyl]propane (p-BAPP), 3,3',4,4'-benzophenetetraacarboxylic anhydride (BTDA) and p-aminopropyltrimetoxysilane (APrTMOS), is synthesized, and then phenyltrimethoxysilane; PhSi(OCH{sub 3}){sub 3} and tris(2,4-pentanedionatio) aluminum(III); Al(C{sub 5}H{sub 7}O{sub 2}){sub 3} are added and mixed thoroughly. Following curing, the polyimide/PhSiOx/Al{sub 2}O{sub 3} hybrid films exhibit high transparency and flexibility. The adhesion improvement between copper and polyimides hybrid films is investigated by peel test and the X-ray photoelectron spectroscopy (XPS) measurements are made to demonstrate that the Si elements from APrTMOS and PhSiOx migrate from the surface to the bulk of polyimide hybrids. Dynamic mechanical analysis (DMA) indicates that the glass transition temperature (Tg) increases with the Al{sub 2}O{sub 3} content and the tan{delta} peak becomes broader and lower. The nano-sized Al{sub 2}O{sub 3} particles are highly dispersed in the hybrid film, as detected by high-resolution transmission electron microscopy (HRTEM). The polyimide/PhSiOx/Al{sub 2}O{sub 3} films show good peel strength with copper, as well as high Tg values. They may therefore have potential applications in flexible print circuits.

  10. Analysis of the Temporal Response of Coupled Asymmetrical Zero-Power Subcritical Bare Metal Reactor Systems

    Energy Technology Data Exchange (ETDEWEB)

    Klain, Kimberly L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-06-21

    The behavior of symmetrical coupled-core systems has been extensively studied, yet there is a dearth of research on asymmetrical systems due to the increased complexity of the analysis of such systems. In this research, the multipoint kinetics method is applied to asymmetrical zeropower, subcritical, bare metal reactor systems. Existing research on asymmetrical reactor systems assumes symmetry in the neutronic coupling; however, it will be shown that this cannot always be assumed. Deep subcriticality adds another layer of complexity and requires modification of the multipoint kinetics equations to account for the effect of the external neutron source. A modified set of multipoint kinetics equations is derived with this in mind. Subsequently, the Rossi-alpha equations are derived for a two-region asymmetrical reactor system. The predictive capabilities of the radiation transport code MCNP6 for neutron noise experiments are shown in a comparison to the results of a series of Rossi-alpha measurements performed by J. Mihalczo utilizing a coupled set of symmetrical bare highly-enriched uranium (HEU) cylinders. The ptrac option within MCNP6 can generate time-tagged counts in a cell (list-mode data). The list-mode data can then be processed similarly to measured data to obtain values for system parameters such as the dual prompt neutron decay constants observable in a coupled system. The results from the ptrac simulations agree well with the historical measured values. A series of case studies are conducted to study the effects of geometrical asymmetry in the coupling between two bare metal HEU cylinders. While the coupling behavior of symmetrical systems has been reported on extensively, that of asymmetrical systems remains sparse. In particular, it appears that there has been no previous research in obtaining the coupling time constants for asymmetrically-coupled systems. The difficulty in observing such systems is due in part to the inability to determine the

  11. RNA folding: structure prediction, folding kinetics and ion electrostatics.

    Science.gov (United States)

    Tan, Zhijie; Zhang, Wenbing; Shi, Yazhou; Wang, Fenghua

    2015-01-01

    Beyond the "traditional" functions such as gene storage, transport and protein synthesis, recent discoveries reveal that RNAs have important "new" biological functions including the RNA silence and gene regulation of riboswitch. Such functions of noncoding RNAs are strongly coupled to the RNA structures and proper structure change, which naturally leads to the RNA folding problem including structure prediction and folding kinetics. Due to the polyanionic nature of RNAs, RNA folding structure, stability and kinetics are strongly coupled to the ion condition of solution. The main focus of this chapter is to review the recent progress in the three major aspects in RNA folding problem: structure prediction, folding kinetics and ion electrostatics. This chapter will introduce both the recent experimental and theoretical progress, while emphasize the theoretical modelling on the three aspects in RNA folding.

  12. Remarkable magnetism and ferromagnetic coupling in semi-sulfuretted transition-metal dichalcogenides.

    Science.gov (United States)

    Zhou, Yungang; Yang, Chengfei; Xiang, Xia; Zu, Xiaotao

    2013-09-14

    Motivated by recent investigations of semi-decorated two dimensional honeycomb structures, we demonstrated, via spin-polarized molecular-dynamics simulations and density-functional-theory calculations, that semi-sulfuretted transition-metal dichalcogenides of MX type (M = V, Nb, Ta; X = S, Se, Te) are stable and display remarkable magnetism. The unpaired d electron of the transition-metal atom arising from the breakage of the M-X bond is the mechanism behind the induction of the magnetism. The remarkable magnetism of the transition-metal atoms is caused by ferromagnetic coupling due to the competitive effects of through-bond interactions and through-space interactions. This implies the existence of an infinite ferromagnetic sheet with structural integrity and magnetic homogeneity. The estimated Curie temperatures suggest that the ferromagnetism can be achieved above room temperature in the VS, VSe, VTe, NbTe and TaTe sheets. Depending on the species of the M and X atoms, the MX sheet can be a magnetic metal, magnetic semiconductor or half-metal. Furthermore, in contrary to the recently reported semi-hydrogenated and semi-fluorinated layered materials consisting of B, C, N, etc., the MX sheets with many unpaired d electrons can offer a much stronger spin polarization and possess a more stable ferromagnetic coupling, which is critical for practical nanoscale device applications.

  13. Electromagnetic-acoustic coupling in ferromagnetic metals at liquid-helium temperatures

    DEFF Research Database (Denmark)

    Gordon, R A

    1981-01-01

    Electromagnetic-acoustic coupling at the surface and in the bulk of ferromagnetic metals at liquid-helium temperatures has been studied using electromagnetically excited acoustic standing-wave resonances at MHz frequencies in a number of ferromagnetic metals and alloys of commercial interest....... The experimental results are compared with similar measurements at room temperature in the same and in different samples as well as with existing theoretical descriptions of the phenomenon. Journal of Applied Physics is copyrighted by The American Institute of Physics....

  14. Effects of spin-orbit coupling on the spin structure of deposited transition-metal clusters

    Science.gov (United States)

    Mankovsky, S.; Bornemann, S.; Minár, J.; Polesya, S.; Ebert, H.; Staunton, J. B.; Lichtenstein, A. I.

    2009-07-01

    The influence of the spin-orbit coupling on the magnetic structure of deposited transition-metal nanostructures has been studied by fully relativistic electronic-structure calculations. The interplay of exchange coupling and magnetic anisotropy was monitored by studying the corresponding magnetic torque calculated within ab initio and model approaches. We find that a spin-orbit-induced Dzyaloshinski-Moriya interaction has a profound effect on the spin structure of such complex magnetic systems and that in combination with magnetic anisotropies and isotropic exchange this can result in peculiar magnetic properties.

  15. Giant negative linear compression positively coupled to massive thermal expansion in a metal-organic framework.

    Science.gov (United States)

    Cai, Weizhao; Katrusiak, Andrzej

    2014-07-04

    Materials with negative linear compressibility are sought for various technological applications. Such effects were reported mainly in framework materials. When heated, they typically contract in the same direction of negative linear compression. Here we show that this common inverse relationship rule does not apply to a three-dimensional metal-organic framework crystal, [Ag(ethylenediamine)]NO3. In this material, the direction of the largest intrinsic negative linear compression yet observed in metal-organic frameworks coincides with the strongest positive thermal expansion. In the perpendicular direction, the large linear negative thermal expansion and the strongest crystal compressibility are collinear. This seemingly irrational positive relationship of temperature and pressure effects is explained and the mechanism of coupling of compressibility with expansivity is presented. The positive coupling between compression and thermal expansion in this material enhances its piezo-mechanical response in adiabatic process, which may be used for designing new artificial composites and ultrasensitive measuring devices.

  16. Coupling of metals and biominerals: characterizing the interface between ferromagnetic shape-memory alloys and hydroxyapatite.

    Science.gov (United States)

    Allenstein, Uta; Selle, Susanne; Tadsen, Meike; Patzig, Christian; Höche, Thomas; Zink, Mareike; Mayr, Stefan G

    2015-07-22

    Durable, mechanically robust osseointegration of metal implants poses one of the largest challenges in contemporary orthopedics. The application of biomimetic hydroxyapatite (HAp) coatings as mediators for enhanced mechanical coupling to natural bone constitutes a promising approach. Motivated by recent advances in the field of smart metals that might open the venue for alternate therapeutic concepts, we explore their mechanical coupling to sputter-deposited HAp layers in a combined experimental-theoretical study. While experimental delamination tests and comprehensive structural characterization, including high-resolution transmission electron microscopy, are utilized to establish structure-property relationships, density functional theory based total energy calculations unravel the underlying physics and chemistry of bonding and confirm the experimental findings. Experiments and modeling indicate that sputter-deposited HAp coatings are strongly adherent to the exemplary ferromagnetic shape-memory alloys, Ni-Mn-Ga and Fe-Pd, with delamination stresses and interface bonding strength exceeding the physiological scales by orders of magnitude.

  17. Inductively coupled plasma mass spectrometer with laser ablation metal ions release detection in the human mouth

    Science.gov (United States)

    Kueerova, Hana; Dostalova, Tatjana; Prochazkova, J.

    2002-06-01

    Presence of more dental alloys in oral cavity often causes pathological symptoms. Due to various and multi-faced symptomatology, they tend to be a source of significant problems not only for the patient but also for the dentist. Metal ions released from alloys can cause subjective and objective symptoms in mouth. The aim of this study was detection of metal elements presence in saliva. There were 4 groups of examined persons: with intact teeth (15 individuals) with metallic restorations, pathological currents 5-30 (mu) A, multi-faced subjective symptomatology and uncharacteristic objective diagnosis (32 patients), with metallic restorations and no subjective symptoms (14 persons) and with metallic restorations, without pathological currents and with problems related to galvanism (13 patients). Presence of 14 metal elements was checked by inductively coupled plasma mass spectrometer with laser ablation. Nd:YAG laser detector was used. There were significant differences in content of silver, gold and mercury between persons with intact teeth and other three groups. There were no differences found between subjects with and without galvanic currents, and presence of subjective and objective symptoms.

  18. Coupled edge plasmon modes of metal/dielectric multi-wedges

    International Nuclear Information System (INIS)

    Wang Xuan-Zhang

    2013-01-01

    We present a metallic/dielectric multi-wedge model to investigate the coupled edge plasmon modes (CEPMs), where all wedges have a common edge and the wave propagates along the edge direction. A general theoretical method valid to many practical structures is presented. The analytical dispersion relations of CEPMs in these structures are obtained and the CEPM properties are discussed with numerical results and the dispersion relations. For all structures mentioned in this paper, we find that the structures containing an even number of metallic wedges have four CEPMs and those with an odd-number of metallic wedges have two CEPMs. Further, the periodic structures containing any odd number of periods and any even number of periods possess their common CEPMs, respectively

  19. Separation of some metal ions using coupled transport supported liquid membranes

    International Nuclear Information System (INIS)

    Chaudhary, M.A.

    1993-01-01

    Liquid membrane extraction processes has become very popular due to their superiority in many ways over other separation techniques. In coupled transport membranes the metal ions can be transported across the membrane against their concentration gradient under the influence of chemical potential difference. Liquid membranes consisting of a carrier-cum-diluent, supported in microporous polymeric hydrophobic films have been studied for transport of metal ions like U(VI), Cr(VI), Be(II), V(V), Ti(IV), Zn(II), Cd(II), Hf(IV), W(VI), and Co(II). The present paper presents basic data with respect to flux and permeabilities of these metal ions across membranes based on experimental results and theoretical equations, using different carriers and diluents and provides a brief reference to possibility of such membranes for large scale applications. (author)

  20. Role of Interchain Coupling in the Metallic State of Conducting Polymers

    Science.gov (United States)

    Kim, Nara; Lee, Byoung Hoon; Choi, Doowhan; Kim, Geunjin; Kim, Heejoo; Kim, Jae-Ryoung; Lee, Jongjin; Kahng, Yung Ho; Lee, Kwanghee

    2012-09-01

    We investigated the charge dynamics of the conductivity enhancement from 2 to 1000S/cm in poly(3, 4-ethylenedioxythiophene):poly(styrenesulfonate) as induced by structural changes through the addition of a polar solvent and the following solvent bath treatment. Our results indicate that the addition of a polar solvent selectively enhanced the π-π coupling of the polymer chains, resulting in the reduction of disorder and tremendously increasing the charge carrier mobility, which yielded an insulator-to-metal transition. In contrast, the following solvent bath treatment selectively enhanced the intergrain coupling, which did not affect the disorder or the mobility but increased the charge carrier density. Therefore, we demonstrate that the conduction-character defining disorder in this conducting polymer system is determined by the extent of interchain coupling.

  1. The application of the inductively coupled plasma system to the simultaneous determination of precious metals

    International Nuclear Information System (INIS)

    Watson, A.E.; Russell, G.M.; Middleton, H.R.; Davenport, F.F.

    1983-01-01

    This report describes the development of a spectrochemical technique using excitation by an inducticely coupled plasma (ICP) source for the simultaneous determination of the precious metals (defined here as gold, silver, and all the platinum-group metals except osmium) in a wide variety of samples from a plant for the extraction and refining of platinum metal. The limits of detection for the analytes were determined in various acid and salt media and, under the conditions used, ranged from 20 to 100ng/l. The analytes were determined in the presence of a thousandfold excess of each of the other precious metals used as a matrix element. Some severe interferences were noted but were ascribed to spectral-line overlap or to contamination of the matrix material. Various dissolution techniques, based upon standard procedures applied in the precious-metals industry, were used, depending on the particular type of material treated. The spectrometer was calibrated by the use of solutions containing the analytes, sodium chloride, and acid, with scandium as the internal standard. The accuracy and precision of the technique, established by the analysis of many samples of each type, were found to be satisfactory when close attention was paid to detail in the preparation of the analytical solution. The relative standard deviation of the method ranges from 0,005 to 0,05, depending on the element being determined

  2. Fracture of a metal/ceramic couple: Tantalum[titanium]/sapphire

    International Nuclear Information System (INIS)

    Bartlett, A.H.

    1991-01-01

    A study of the fracture behavior of a model metal/ceramic diffusion bonded couple was performed using the system Ta[Ti]/Al 2 O 3 . Residual stress cracking due to thermal expansion misfit between the metal and ceramic was examined. Depending on composition, the alloy could have a coefficient of thermal expansion (CTE) greater than or less than that of the sapphire. When the CTE of the alloy was greater than that of the sapphire, cracking occurred in the ceramic upon cooling down from bonding temperatures. Conversely, when the CTE of the metal was less than the sapphire, failure occurred along the metal/ceramic interface. Mechanical test specimens were fabricated in order to study fracture along a metal/ceramic interface containing reaction products. The formation of these reaction products was in accord with the Ti-Ta-Al ternary phase diagram. Concentration profiles were measured in the TEM and allowed for interdiffusion coefficients in the α 2 phase at 900 C to be determined

  3. Threefold symmetric magnetic two-ion coupling in hcp rare-earth metals

    International Nuclear Information System (INIS)

    Jensen, J.

    1997-01-01

    The heavy rare earths crystallize in the hcp structure. Most of magnetic couplings between two ions in these metals are independent of the two different orientations of the hexagonal layers. However, trigonal anisotropy terms may occur, reflecting that c-axis is only threefold axis. In the presence of a trigonal coupling the symmetry is reduced, and the double-zone representation in the c-direction ceases to be valid. The strong interaction between the transverse optical phonons and the acoustic spin waves propagating in the c-direction of Yb detected more than twenty years ago, was the first example of a trigonal coupling found in these systems. A few years ago a careful neutron-diffraction study of the c-axis modulated magnetic structures in Er showed the presence of higher harmonics at positions along the c-axis translated by odd multiple of 2φ/c. This indicates distortions of the structures due to trigonal couplings, and the same characteristic phenomenon has now been also observed in Ho. Additionally, mean field calculations show that a trigonal coupling in Ho is required, in order to explain the increase in the commensurable effects observed for the 8 and 10 layered periodic structures, when a field is applied along the c-axis. (author)

  4. Nucleophilic substitution and oxidative coupling in reaction of metallated lithium salt of acetic acid with 1,2-dibromoethane

    OpenAIRE

    Chanysheva, A.; Zorin, A.; Klimakov, V.; Spirikhin, L.; Zorin, V.

    2009-01-01

    When lithium salt of acetic acid metallated by lithium diisopropylamide in tetrahydrofuran interacts with 1,2-dibromoethane products of nucleophilic substitution of bromine atoms for oxycarbomethyl group and oxidative coupling of acetoxydianions are obtained.

  5. Potential of Cassia alata L. Coupled with Biochar for Heavy Metal Stabilization in Multi-Metal Mine Tailings

    Science.gov (United States)

    Huang, Lige; Li, Yuanyuan; Zhao, Man; Chao, Yuanqing; Qiu, Rongliang; Yang, Yanhua

    2018-01-01

    To explore the effect of different biochars on Cassia alata L. growth and heavy metal immobilization in multi-metal mine tailings, a 100-day pot experiment was conducted. Three biochars derived from Hibiscus cannabinus core (HB), sewage sludge (SB) and chicken manure (MB), were added to mine tailings at rates of 0.4%, 1% and 3% (w/w). The results showed that the root biomass, shoot biomass, plant height and root length were 1.2–2.8, 1.7–3.2, 1–1.5 and 1.6–3.3 times of those in the control group, respectively. Pb, Zn, Cu, Cd and As contents in the shoot decreased by 63.9–89.5%, 46.9–66.0%, 32.7–62.4%, 40.4–76.4% and 54.9–77.5%, respectively. The biochar significantly increased the pH and decreased the mild acid-soluble Pb and Cu concentrations in the mine tailings. Specifically, SB immobilized Pb and Cu better than MB and HB did, although it did not immobilize As, Zn or Cd. Meanwhile, more attention should be paid to the potential As release as the biochar application rate increases. In conclusion, Cassia alata L. coupled with 3% of SB could be an effective measure for restoring multi-metal mine tailings. This study herein provided a promising ecological restoration technique for future practice of heavy metal stabilization in mine tailings. PMID:29534505

  6. Structures of the rare-cutting restriction endonuclease NotI reveal a unique metal binding fold involved in DNA binding.

    Science.gov (United States)

    Lambert, Abigail R; Sussman, Django; Shen, Betty; Maunus, Robert; Nix, Jay; Samuelson, James; Xu, Shuang-Yong; Stoddard, Barry L

    2008-04-01

    The structure of the rare-cutting restriction endonuclease NotI, which recognizes the 8 bp target 5'-GCGGCCGC-3', has been solved with and without bound DNA. Because of its specificity (recognizing a site that occurs once per 65 kb), NotI is used to generate large genomic fragments and to map DNA methylation status. NotI contains a unique metal binding fold, found in a variety of putative endonucleases, occupied by an iron atom coordinated within a tetrahedral Cys4 motif. This domain positions nearby protein elements for DNA recognition, and serves a structural role. While recognition of the central six base pairs of the target is accomplished via a saturated hydrogen bond network typical of restriction enzymes, the most peripheral base pairs are engaged in a single direct contact in the major groove, reflecting reduced pressure to recognize those positions. NotI may represent an evolutionary intermediate between mobile endonucleases (which recognize longer target sites) and canonical restriction endonucleases.

  7. Spin-Orbit Coupling Drives Femtosecond Nonadiabatic Dynamics in a Transition Metal Compound.

    Science.gov (United States)

    Carbery, William P; Verma, Archana; Turner, Daniel B

    2017-03-16

    Transient absorption measurements conducted using broadband, 6 fs laser pulses reveal unexpected femtosecond dynamics in the [IrBr 6 ] 2- model system. Vibrational spectra and the X-ray crystal structure indicate that these dynamics are not induced by a Jahn-Teller distortion, a type of conical intersection typically associated with the spectral features of transition metal compounds. Two-dimensional electronic spectra of [IrBr 6 ] 2- contain 23 cross peaks, which necessarily arise from spin-orbit coupling. Real-valued 2D spectra support a spectroscopic basis where strong nonadiabatic coupling, ascribed to multiple conical intersections, mediates rapid energy relaxation to the lowest-energy excited state. Subsequent analysis gives rise to a more generalized description of a conical intersection as a degeneracy between two adiabatic states having the same total angular momentum.

  8. Coupling mid-infrared light from a photonic crystal waveguide to metallic transmission lines

    Energy Technology Data Exchange (ETDEWEB)

    Blanco-Redondo, Andrea, E-mail: andrea.blanco@tecnalia.com, E-mail: r.hillenbrand@nanogune.eu [ICT-European Software Institute Division, Tecnalia, Ibaizabal Bidea, Ed. 202, 48170 Zamudio, Bizkaia (Spain); Dpto. Electronica y Telecom., E.T.S. Ingeniería Bilbao, UPV/EHU, Alda. Urquijo, 48103 Bilbao, Bizkaia (Spain); Sarriugarte, Paulo [Nanooptics Group, CIC nanoGUNE Consolider, 20018 Donostia–San Sebastian, Gipuzkoa (Spain); Garcia-Adeva, Angel [Dpto. Fisica Aplicada I, E.T.S. Ingeniería de Bilbao, UPV-EHU, Alda. Urquijo, 48103 Bilbao, Bizkaia (Spain); Zubia, Joseba [Dpto. Electronica y Telecom., E.T.S. Ingeniería Bilbao, UPV/EHU, Alda. Urquijo, 48103 Bilbao, Bizkaia (Spain); Hillenbrand, Rainer, E-mail: andrea.blanco@tecnalia.com, E-mail: r.hillenbrand@nanogune.eu [Nanooptics Group, CIC nanoGUNE Consolider, 20018 Donostia–San Sebastian, Gipuzkoa (Spain); IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Bizkaia (Spain)

    2014-01-06

    We propose and theoretically study a hybrid structure consisting of a photonic crystal waveguide (PhC-wg) and a two-wire metallic transmission line (TL), engineered for efficient transfer of mid-infrared (mid-IR) light between them. An efficiency of 32% is obtained for the coupling from the transverse magnetic (TM) photonic mode to the symmetric mode of the TL, with a predicted intensity enhancement factor of 53 at the transmission line surface. The strong coupling is explained by the small phase velocity mismatch and sufficient spatial overlapping between the modes. This hybrid structure could find applications in highly integrated mid-IR photonic-plasmonic devices for biological and gas sensing, among others.

  9. Hanle Magnetoresistance in Thin Metal Films with Strong Spin-Orbit Coupling.

    Science.gov (United States)

    Vélez, Saül; Golovach, Vitaly N; Bedoya-Pinto, Amilcar; Isasa, Miren; Sagasta, Edurne; Abadia, Mikel; Rogero, Celia; Hueso, Luis E; Bergeret, F Sebastian; Casanova, Fèlix

    2016-01-08

    We report measurements of a new type of magnetoresistance in Pt and Ta thin films. The spin accumulation created at the surfaces of the film by the spin Hall effect decreases in a magnetic field because of the Hanle effect, resulting in an increase of the electrical resistance as predicted by Dyakonov [Phys. Rev. Lett. 99, 126601 (2007)]. The angular dependence of this magnetoresistance resembles the recently discovered spin Hall magnetoresistance in Pt/Y(3)Fe(5)O(12) bilayers, although the presence of a ferromagnetic insulator is not required. We show that this Hanle magnetoresistance is an alternative simple way to quantitatively study the coupling between charge and spin currents in metals with strong spin-orbit coupling.

  10. 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.)

  11. Magnetic circular dichroism spectroscopy of weakly exchange coupled transition metal dimers: A model study

    DEFF Research Database (Denmark)

    Piligkos, S.; Slep, L.D.; Weyhermuller, T.

    2009-01-01

    bands of the minority spin Ni(II) ligand field bands were observed to change sign relative to the parent complex 2. This behavior has been analyzed. The present work hence provides a benchmark study for the application of MCD spectroscopy to weakly interacting transition metal dinners. (C) 2008 Elsevier......A detailed study of the magnetic circular dichroism (MCD) spectra of weakly exchange coupled transition metal heterodimers is reported. The systems consist of three isostructural complexes of the type [LM(III)(PyA)(3)M(II)](ClO4)(2) where L represents 1,4,7-trimethyl-1,4,7-triazacyclonanane and Py......A- is the monoanion of pyridine-2-aldoxime. The trivalent metal ion M(III) is either diamagnetic Ga(III) or paramagnetic Cr(III) (S-Cr = 3/2). The divalent metal ion M(II) is either diamagnetic Zn(II) or paramagnetic Ni(II) (S-Ni = 1). The three systems 1 (CrZn), 2 (GaNi) and 3 (CrNi) have been structurally...

  12. Inductive coupling between overhead power lines and nearby metallic pipelines. A neural network approach

    Directory of Open Access Journals (Sweden)

    Levente Czumbil

    2015-12-01

    Full Text Available The current paper presents an artificial intelligence based technique applied in the investigation of electromagnetic interference problems between high voltage power lines (HVPL and nearby underground metallic pipelines (MP. An artificial neural network (NN solution has been implemented by the authors to evaluate the inductive coupling between HVPL and MP for different constructive geometries of an electromagnetic interference problem considering a multi-layer soil structure. Obtained results are compared to solutions provided by a finite element method (FEM based analysis and considered as reference. The advantage of the proposed method yields in a simplified computation model compared to FEM, and implicitly a lower computational time.

  13. Relaxation dynamics of a quantum emitter resonantly coupled to a metal nanoparticle

    DEFF Research Database (Denmark)

    Nerkararyan, K. V.; Bozhevolnyi, S. I.

    2014-01-01

    consequence of this relaxation process is that the emission, being largely determined by the MNP, comes out with a substantial delay. A large number of system parameters in our analytical description opens new possibilities for controlling quantum emitter dynamics. (C) 2014 Optical Society of America......The presence of a metal nanoparticle (MNP) near a quantum dipole emitter, when a localized surface plasmon mode is excited via the resonant coupling with an excited quantum dipole, dramatically changes the relaxation dynamics: an exponential decay changes to step-like behavior. The main physical...

  14. Thermo-elasto-visco-plastic constitutive equations fully coupled with ductile damage. Application to metal cutting by chip formation

    International Nuclear Information System (INIS)

    Lestriez, P.; Cherouat, A.; Saanouni, K.; Mariage, J.F.

    2004-01-01

    A fully coupled (strong coupling) thermo-elasto-visco-plastic-damage constitutive equations based on the state variables under large plastic deformation developed for metal forming simulation are presented. The relevant numerical aspects concerning either the local integration scheme as well as the global resolution strategy are discussed. This model is implemented into ABAQUS/EXPLICIT using the Vumat user subroutine. Applications are made to the orthogonal metal cutting by chip formation and segmentation. The interaction between hardening plasticity, ductile damage and thermal effects are carefully analyzed. The numerical results obtained with this procedure based on the damage coupling are compared with those obtained with the classical procedure neglecting the damage effect

  15. Tunneling conductance oscillations in spin-orbit coupled metal-insulator-superconductor junctions

    Science.gov (United States)

    Kapri, Priyadarshini; Basu, Saurabh

    2018-01-01

    The tunneling conductance for a device consisting of a metal-insulator-superconductor (MIS) junction is studied in presence of Rashba spin-orbit coupling (RSOC) via an extended Blonder-Tinkham-Klapwijk formalism. We find that the tunneling conductance as a function of an effective barrier potential that defines the insulating layer and lies intermediate to the metallic and superconducting electrodes, displays an oscillatory behavior. The tunneling conductance shows high sensitivity to the RSOC for certain ranges of this potential, while it is insensitive to the RSOC for others. Additionally, when the period of oscillations is an odd multiple of a certain value of the effective potential, the conductance spectrum as a function of the biasing energy demonstrates a contrasting trend with RSOC, compared to when it is not an odd multiple. The explanations for the observation can be found in terms of a competition between the normal and Andreev reflections. Similar oscillatory behavior of the conductance spectrum is also seen for other superconducting pairing symmetries, thereby emphasizing that the insulating layer plays a decisive role in the conductance oscillations of a MIS junction. For a tunable Rashba coupling, the current flowing through the junction can be controlled with precision.

  16. Capacitively coupled pickup in MCP-based photodetectors using a conductive metallic anode

    Energy Technology Data Exchange (ETDEWEB)

    Angelico, E.; Seiss, T. [Enrico Fermi Institute, University of Chicago, 5640 S Ellis Ave, Chicago, IL 60637 (United States); Adams, B. [Incom, Inc., 294 SouthBridge Rd, Charlton, Massachusetts 01507 (United States); Elagin, A.; Frisch, H.; Spieglan, E. [Enrico Fermi Institute, University of Chicago, 5640 S Ellis Ave, Chicago, IL 60637 (United States)

    2017-02-21

    We have designed and tested a robust 20×20 cm{sup 2} thin metal film internal anode capacitively coupled to an external array of signal pads or micro-strips for use in fast microchannel plate photodetectors. The internal anode, in this case a 10 nm-thick NiCr film deposited on a 96% pure Al{sub 2}O{sub 3} 3 mm-thick ceramic plate and connected to HV ground, provides the return path for the electron cascade charge. The multi-channel pickup array consists of a printed-circuit card or glass plate with metal signal pickups on one side and the signal ground plane on the other. The pickup can be put in close proximity to the bottom outer surface of the sealed photodetector, with no electrical connections through the photodetector hermetic vacuum package other than a single ground connection to the internal anode. Two pickup patterns were tested using a small commercial MCP-PMT as the signal source: 1) parallel 50 Ω 25-cm-long micro-strips with an analog bandwidth of 1.5 GHz, and 2) a 20×20 cm{sup 2} array of 2-dimensional square ‘pads’ with sides of 1.27 cm or 2.54 cm. The rise-time of the fast input pulse is maintained for both pickup patterns. For the pad pattern, we observe 80% of the directly coupled amplitude. For the strip pattern we measure 34% of the directly coupled amplitude on the central strip of a broadened signal. The physical decoupling of the photodetector from the pickup pattern allows easy customization for different applications while maintaining high analog bandwidth.

  17. Complex band structures of transition metal dichalcogenide monolayers with spin–orbit coupling effects

    International Nuclear Information System (INIS)

    Szczęśniak, Dominik; Ennaoui, Ahmed; Ahzi, Saïd

    2016-01-01

    Recently, the transition metal dichalcogenides have attracted renewed attention due to the potential use of their low-dimensional forms in both nano- and opto-electronics. In such applications, the electronic and transport properties of monolayer transition metal dichalcogenides play a pivotal role. The present paper provides a new insight into these essential properties by studying the complex band structures of popular transition metal dichalcogenide monolayers (MX 2 , where M   =  Mo, W; X   =  S, Se, Te) while including spin–orbit coupling effects. The conducted symmetry-based tight-binding calculations show that the analytical continuation from the real band structures to the complex momentum space leads to nonlinear generalized eigenvalue problems. Herein an efficient method for solving such a class of nonlinear problems is presented and yields a complete set of physically relevant eigenvalues. Solutions obtained by this method are characterized and classified into propagating and evanescent states, where the latter states manifest not only monotonic but also oscillatory decay character. It is observed that some of the oscillatory evanescent states create characteristic complex loops at the direct band gap of MX 2 monolayers, where electrons can directly tunnel between the band gap edges. To describe these tunneling currents, decay behavior of electronic states in the forbidden energy region is elucidated and their importance within the ballistic transport regime is briefly discussed. (paper)

  18. Complex band structures of transition metal dichalcogenide monolayers with spin-orbit coupling effects

    Science.gov (United States)

    Szczęśniak, Dominik; Ennaoui, Ahmed; Ahzi, Saïd

    2016-09-01

    Recently, the transition metal dichalcogenides have attracted renewed attention due to the potential use of their low-dimensional forms in both nano- and opto-electronics. In such applications, the electronic and transport properties of monolayer transition metal dichalcogenides play a pivotal role. The present paper provides a new insight into these essential properties by studying the complex band structures of popular transition metal dichalcogenide monolayers (MX 2, where M  =  Mo, W; X  =  S, Se, Te) while including spin-orbit coupling effects. The conducted symmetry-based tight-binding calculations show that the analytical continuation from the real band structures to the complex momentum space leads to nonlinear generalized eigenvalue problems. Herein an efficient method for solving such a class of nonlinear problems is presented and yields a complete set of physically relevant eigenvalues. Solutions obtained by this method are characterized and classified into propagating and evanescent states, where the latter states manifest not only monotonic but also oscillatory decay character. It is observed that some of the oscillatory evanescent states create characteristic complex loops at the direct band gap of MX 2 monolayers, where electrons can directly tunnel between the band gap edges. To describe these tunneling currents, decay behavior of electronic states in the forbidden energy region is elucidated and their importance within the ballistic transport regime is briefly discussed.

  19. Profiling metals in Cordyceps sinensis by using inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    Wei, Xin; Hu, Hankun; Zheng, Baogeng; Arslan, Zikri; Huang, Hung-Chung; Mao, Weidong; Liu, Yi-Ming

    2017-01-28

    Cordyceps sinensis ( C. sinensis ) is a natural product that has diverse nutritional and medicinal values. Since the availability of natural C. sinensis becomes limited its authentication and quality control is of high significance. Herein we report on profiling of metals in C. sinensis by using inductively coupled plasma mass spectrometry (ICP-MS). The analysis reveals that C. sinensis contains a wide array of essential elements, including P, Mg, Zn, Cu, Fe, etc. Toxic metals detected are Cd, Pb, and As. In all five samples analyzed Pb contents are below 2.0 ppm. Arsenic level in C. sinensis caterpillar is significantly higher than that in its mycelium and varies from 3.0 to 32 ppm likely due to soil contamination. It's for the first time demonstrated in this work that clustering analysis on the proposed metal profiles consisting of 24 elements is very useful to identify "abnormal" C. sinensis samples, thus adding another dimension to the effective means for authentication and quality assessment of this highly demanded previous natural product.

  20. Thermo-magneto-elastoplastic coupling model of metal magnetic memory testing method for ferromagnetic materials

    Science.gov (United States)

    Shi, Pengpeng; Zhang, Pengcheng; Jin, Ke; Chen, Zhenmao; Zheng, Xiaojing

    2018-04-01

    Metal magnetic memory (MMM) testing (also known as micro-magnetic testing) is a new non-destructive electromagnetic testing method that can diagnose ferromagnetic materials at an early stage by measuring the MMM signal directly on the material surface. Previous experiments have shown that many factors affect MMM signals, in particular, the temperature, the elastoplastic state, and the complex environmental magnetic field. However, the fact that there have been only a few studies of either how these factors affect the signals or the physical coupling mechanisms among them seriously limits the industrial applications of MMM testing. In this paper, a nonlinear constitutive relation for a ferromagnetic material considering the influences of temperature and elastoplastic state is established under a weak magnetic field and is used to establish a nonlinear thermo-magneto-elastoplastic coupling model of MMM testing. Comparing with experimental data verifies that the proposed theoretical model can accurately describe the thermo-magneto-elastoplastic coupling influence on MMM signals. The proposed theoretical model can predict the MMM signals in a complex environment and so is expected to provide a theoretical basis for improving the degree of quantification in MMM testing.

  1. Coplanar UHF RFID tag antenna with U-shaped inductively coupled feed for metallic applications.

    Directory of Open Access Journals (Sweden)

    Karrar Naji Salman

    Full Text Available In this paper, we present a novel compact, coplanar, tag antenna design for metallic objects. Electrically small antenna has designed for a UHF RFID (860-960 MHz based on a proximity-coupled feed through. Furthermore, two symmetrical Via-loaded coplanar grounds fed by a U-shaped inductively coupled feed through an embedded transmission line. This configuration results in an antenna with dimensions of 31 × 19.5 × 3.065 mm3 at 915 MHz, and the total gain for the antenna is 0.12 dBi. The Via-loaded coplanar and U-shaped inductively coupled feeds allow the antenna to provide flexible tuning in terms of antenna impedance. In addition, a figure of merit is applied for the proposed tag antenna, and the results are presented. The read range is measured to be 4.2 m, which is very close to simulated values. This antenna measurement shows very good agreement with simulations.

  2. Impact of an interbedded viscous décollement on the structural and kinematic coupling in fold-and-thrust belts: Insights from analogue modeling

    Science.gov (United States)

    Borderie, Sandra; Graveleau, Fabien; Witt, César; Vendeville, Bruno C.

    2018-01-01

    Fold-and-thrust belts (FTBs) can be segmented both across and along strike because of various factors including tectonic and stratigraphic inheritance. In this study, we investigated along/across-strike structural interactions in a FTB propagating toward a foreland which displays contrasted lithological sequences. A set of analogue models was performed in a compressional box where a single viscous level of varying width was interbedded within a frictional series. The tectonic interaction between the viscous and the frictional provinces was tested both along and across strike. Results indicate that a frictional province influences the along-strike tectonic evolution of an adjacent viscous province. This influence decreases when the width of the viscous province increases. The frictional provinces control the taper, structural style, obliquity of the structures' trend and kinematics of the shallow deformation front of the viscous province. Results evidence how far a frictional province can impact the deformation of an adjacent viscous province. For frictional-viscous wedges, it appears that the critical taper theory, which is generally applied in 2-D, should be likely considered in terms of 3-D. Moreover, the kinematics of the deep deformation front shows mutual influences between the adjacent viscous and frictional provinces. Experimental results are compared to natural examples in the Kuqa Basin (Southern Tian Shan, China) and the Salt Range (Pakistan), and give an insight to a better understanding of the dynamics of fold-and-thrust belts bearing a viscous décollement, such as salt.

  3. Crystal Structure of the PAC1R Extracellular Domain Unifies a Consensus Fold for Hormone Recognition by Class B G-Protein Coupled Receptors

    OpenAIRE

    Kumar, Shiva; Pioszak, Augen; Zhang, Chenghai; Swaminathan, Kunchithapadam; Xu, H. Eric

    2011-01-01

    Pituitary adenylate cyclase activating polypeptide (PACAP) is a member of the PACAP/glucagon family of peptide hormones, which controls many physiological functions in the immune, nervous, endocrine, and muscular systems. It activates adenylate cyclase by binding to its receptor, PAC1R, a member of class B G-protein coupled receptors (GPCR). Crystal structures of a number of Class B GPCR extracellular domains (ECD) bound to their respective peptide hormones have revealed a consensus mechanism...

  4. Pd Metal Catalysts for Cross-Couplings and Related Reactions in the 21st Century: A Critical Review.

    Science.gov (United States)

    Biffis, Andrea; Centomo, Paolo; Del Zotto, Alessandro; Zecca, Marco

    2018-02-28

    Cross-couplings and related reactions are a class of highly efficient synthetic protocols that are generally promoted by molecular Pd species as catalysts. However, catalysts based on more or less highly dispersed Pd metal have been also employed for this purpose, and their use, which was largely limited to the Heck reaction until the turn of the century, has been extended in recent years to most reactions of this class. This review provides a critical overview on these recent applications of Pd metal catalysts. Particular attention is devoted to the discussion of the mechanistic pathways that have been proposed to explain the catalytic role of Pd metal. Furthermore, the most outstanding Pd metal based catalytic systems that have emerged are illustrated, together with the development of novel approaches to boost the reactivity of Pd metal. A section summarizing the current industrial applications of Pd metal catalyzed reactions of this kind concludes the review.

  5. Coupled electro-thermal field in a high current electrolysis cell or liquid metal batteries

    Science.gov (United States)

    Cai, Liwei; Ni, Haiou; Lu, Gui-Min; Yu, Jian-Guo

    2018-01-01

    Coupled electro-thermal field exists widely in chemical batteries and electrolysis industry. In this study, a three-dimensional numerical model, which is based on the finite-element software ANSYS, has been built to simulate the electro-thermal field in a magnesium electrolysis cell. The adjustment of the relative position of the anode and cathode can change the energy consumption of the magnesium electrolysis process significantly. Besides, the current intensity has a nonlinear effect on heat balance, and the effects of heat transfer coefficients, electrolysis and air temperature on the heat balance have been released to maintain the thermal stability in a magnesium electrolysis cell. The relationship between structure as well as process parameters and electro-thermal field has been obtained and the simulation results can provide experience for the scale-up design in liquid metal batteries. PMID:29515848

  6. Coupled electro-thermal field in a high current electrolysis cell or liquid metal batteries.

    Science.gov (United States)

    Sun, Ze; Cai, Liwei; Ni, Haiou; Lu, Gui-Min; Yu, Jian-Guo

    2018-02-01

    Coupled electro-thermal field exists widely in chemical batteries and electrolysis industry. In this study, a three-dimensional numerical model, which is based on the finite-element software ANSYS, has been built to simulate the electro-thermal field in a magnesium electrolysis cell. The adjustment of the relative position of the anode and cathode can change the energy consumption of the magnesium electrolysis process significantly. Besides, the current intensity has a nonlinear effect on heat balance, and the effects of heat transfer coefficients, electrolysis and air temperature on the heat balance have been released to maintain the thermal stability in a magnesium electrolysis cell. The relationship between structure as well as process parameters and electro-thermal field has been obtained and the simulation results can provide experience for the scale-up design in liquid metal batteries.

  7. Aluminum sulfate (alum) application interactions with coupled metal and nutrient cycling in a hypereutrophic lake ecosystem.

    Science.gov (United States)

    Nogaro, Geraldine; Burgin, Amy J; Schoepfer, Valerie A; Konkler, Matthew J; Bowman, Katlin L; Hammerschmidt, Chad R

    2013-05-01

    Many lake ecosystems worldwide experience severe eutrophication and associated harmful blooms of cyanobacteria due to high loadings of phosphorus (P). While aluminum sulfate (alum) has been used for decades as chemical treatment of eutrophic waters, the ecological effects of alum on coupled metal and nutrient cycling are not well known. The objective of our study was to investigate the effects of an in-situ alum treatment on aluminum and nutrient (P, N, and S) cycling in a hypereutrophic lake ecosystem. Our results indicate that the addition of alum along with sodium aluminate (as a buffer) increased dissolved aluminum and sulfate in the surface and pore waters, and altered nitrogen cycling by increasing nitrous oxide (N2O) concentrations in the surface water. The increase of aluminum and sulfate may potentially feedback to alter benthic community dynamics. These results enhance our understanding of the unintended ecological consequences of alum treatments in hypereutrophic freshwater ecosystems. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Determination of metals content from wines by inductively coupled plasma mass spectrometry

    International Nuclear Information System (INIS)

    Iordache, Andreea-Maria; Geana, Elisabeta-Irina

    2009-01-01

    Full text: Wine is a widely consumed beverage with thousands of years of tradition. Wine composition strongly determines its quality besides having a great relevance on wine characterization, tipyfication and frauds detection. Wine composition is influenced by many and diverse factors corresponding to the specific production area, such as grape variety, soil and climate, culture, yeast, winemaking practices, transport and storage. Daily consumption of wine in moderate quantities contributes significantly to the requirements of the human organism for essential elements such as Cr, Cu, Zn, Fe, Mn, Co, Ni and Sr. On the other hand, several metals, such as Pb and Cd , are known to be potentially toxic. The objective of this work was to develop a method to determine the metals content in wine samples from Romania. Three samples of difference white wines available in the supermarket was analyzed for identify the presence of: Cr, Cu, Zn, Fe, Mn, Pb, Cd, Co, Ni and Sr by inductively coupled plasma mass spectrometry (ICP-MS). (authors)

  9. Coupling Metallic Nanostructures to Thermally Responsive Polymers Allows the Development of Intelligent Responsive Membranes

    Directory of Open Access Journals (Sweden)

    J. Rubén Morones-Ramírez

    2014-01-01

    Full Text Available Development of porous membranes capable of controlling flow or changing their permeability to specific chemical entities, in response to small changes in environmental stimuli, is an area of appealing research, since these membranes present a wide variety of applications. The synthesis of these membranes has been mainly approached through grafting of environmentally responsive polymers to the surface walls of polymeric porous membranes. This synergizes the chemical stability and mechanical strength of the polymer membrane with the fast response times of the bonded polymer chains. Therefore, different composite membranes capable of changing their effective pore size with environmental triggers have been developed. A recent interest has been the development of porous membranes responsive to light, since these can achieve rapid, remote, noninvasive, and localized flow control. This work describes the synthesis pathway to construct intelligent optothermally responsive membranes. The method followed involved the grafting of optothermally responsive polymer-metal nanoparticle nanocomposites to polycarbonate track-etched porous membranes (PCTEPMs. The nanoparticles coupled to the polymer grafts serve as the optothermal energy converters to achieve optical switching of the pores. The results of the paper show that grafting of the polymer and in situ synthesis of the metallic particles can be easily achieved. In addition, the composite membranes allow fast and reversible switching of the pores using both light and heat permitting control of fluid flow.

  10. A moisture and electric coupling stimulated ionic polymer-metal composite actuator with controllable deformation behavior

    Science.gov (United States)

    Ru, Jie; Zhu, Zicai; Wang, Yanjie; Chen, Hualing; Bian, Changsheng; Luo, Bin; Li, Dichen

    2018-02-01

    Ionic polymer-metal composite (IPMC) actuator can generate large and rapid deformation based on ion migration under a relatively low driving voltage. Under full hydrated conditions, the deformation is always prone to relaxation. At room humidity conditions, the deformation increases substantially at the early stage of actuation, and then decreases gradually. Generally, most researchers considered that the change of water content or relative humidity mainly leads to the deformation instabilities, which severely limits the practical applications of IPMC. In this Letter, a novel actuation mode is proposed to control the deformation behavior of IPMC by employing moisture as an independent or collaborative incentive source together with the electric field. The deformation response is continuously measured under electric field, electric field-moisture coupling stimulus and moisture stimulus. The result shows that moisture can be a favorable driving factor for IPMC actuation. Such an electric field-moisture coupling stimulus can avoid the occurrence of deformation instabilities and guarantee a superior controllable deformation in IPMC actuation. This research provides a new method to obtain stable and large deformation of IPMC, which is of great significance for the guidance of material design and application for IPMC and IPMC-type iEAP materials.

  11. Controlled thermoelectric response of a tunable Rashba coupled metal-insulator-superconductor junction

    Science.gov (United States)

    Kapri, Priyadarshini; Adhikary, Priyanka; Sinha, Shubham; Basu, Saurabh

    2018-05-01

    Thermoelectric effect for metal, insulator and the superconductor junctions has been studied with Rashba spin-orbit coupling (RSOC) being present at the interfaces via modified Blonder-Tinkham-Klapwijk (BTK) theory. We find that the thermopower, as a function of an effective barrier potential that characterizes the intermediate insulating layer, displays an oscillatory behavior. Interesting interplay between the strength of RSOC and the effective barrier potential has been carried out in details in this regard. For specific ranges of the effective barrier potential, RSOC enhances the thermopower, while the reverse happens for other values. Moreover it is found that the effective barrier potential plays a crucial role in determining the thermopower spectrum. For a tunable Rashba coupling, the thermopower of the junction can be controlled with precision, which may useful for the thermoelectric applications, at low temperatures. Further the efficiency of the system is obtained for different pairing correlations of the superconducting lead where we find that the system with a d-wave symmetry is more efficient as compared to a s-wave correlation, in some selective regions of effective barrier potential. It is found that for some selective regions of effective barrier potential, the efficiency of the system increases with RSOC and the opposite happens for other values.

  12. Light out-coupling from LEDs by means of metal nanoparticles; Lichtauskopplung aus LEDs mittels Metallnanoteilchen

    Energy Technology Data Exchange (ETDEWEB)

    Goehler, Tino

    2010-12-17

    The external quantum efficiency of light-emitting diodes (LEDs) based on Al- GaAs/InGaAlP is limited by total internal reflection because of the high refractive index (typically between 3 and 4) of the semiconductor. Metal nanoparticles (MNP) deposited on the surface of the LED can be used as dipole scatterers in order to enhance the emission of the LED. In this thesis, first, single gold nanoparticles of various sizes deposited on such an LED were investigated. A clear enhancement is detected as long as the dipole plasmon resonance of the particle is at a shorter wavelength than the LED emission. If the plasmon resonance coincides with the LED emission or is at a larger wavelength, the enhancement turns into suppression. Numerical simulations indicate that this latter effect is mainly caused by the particle quadrupole resonance producing extra absorption. Arrays of MNPs can be produced by a special mask technique called ''Fischer pattern nanolithography'' and manipulated in shape and size by additional steps. Originally, the MNPs produced by this technique are triangular in shape and turn out to suppress the LED emission. After transformation of the particles to spheres, a clear enhancement was detected. Light that would otherwise remain trapped inside the substrate is coupled out by resonant plasmonic scattering. Investigations on analogous structures on a transparent high-index material (GaP) indicate a stronger coupling between the particles than expected on the basis of literature data. (orig.)

  13. Optimization of coupled plasmonic effects for viable phosphorescence of metal-free purely organic phosphor

    Science.gov (United States)

    Wang, Huan; Jung, Jaehun; Chung, Kyungwha; Lim, Ju Won; You, Youngmin; Kim, Jinsang; Kim, Dong Ha

    2017-10-01

    Metal-free purely organic phosphorescent molecules are attractive alternatives to organometallic and inorganic counterparts because of their low cost and readily tunable optical properties through a wide chemical design window. However, their weak phosphorescent intensity due to inefficient spin-orbit coupling and, consequently, prevailing non-radiative decay processes limit their practical applicability. Here, we systematically studied phosphorescence emission enhancement of a purely organic phosphor system via plasmon resonance energy transfer. By precisely tuning the distance between purely organic phosphor crystals and plasmonic nanostructures using layer-by-layer assembled polyelectrolyte multilayers as a dielectric spacer, maximum 2.8 and 2.5 times enhancement in photoluminescence intensity was observed when the phosphor crystals were coupled with ˜55 nm AuNPs and ˜7 nm AgNPs, respectively, at the distance of 9.6 nm. When the distance is within the range of 3 nm, a dramatic decrease in phosphorescence intensity was observed, while at a larger distance, the plasmonic effect diminished rapidly. The distance-dependent plasmon-induced phosphorescence enhancement mechanism was further investigated by time-resolved photoluminescence measurements. Our results reveal the correlation between the amplification efficiency and plasmonic band, spatial factor, and spectral characteristics of the purely organic phosphor, which may provide an insightful picture to extend the utility of organic phosphors by using surface plasmon-induced emission enhancement scheme.

  14. Mechanistic Insights into Cofactor-Dependent Coupling of RNA Folding and mRNA Transcription/Translation by a Cobalamin Riboswitch

    Directory of Open Access Journals (Sweden)

    Jacob T. Polaski

    2016-05-01

    Full Text Available Riboswitches are mRNA elements regulating gene expression in response to direct binding of a metabolite. While these RNAs are increasingly well understood with respect to interactions between receptor domains and their cognate effector molecules, little is known about the specific mechanistic relationship between metabolite binding and gene regulation by the downstream regulatory domain. Using a combination of cell-based, biochemical, and biophysical techniques, we reveal the specific RNA architectural features enabling a cobalamin-dependent hairpin loop docking interaction between receptor and regulatory domains. Furthermore, these data demonstrate that docking kinetics dictate a regulatory response involving the coupling of translation initiation to general mechanisms that control mRNA abundance. These results yield a comprehensive picture of how RNA structure in the riboswitch regulatory domain enables kinetically constrained ligand-dependent regulation of gene expression.

  15. Coupled Geochemical and Hydrological Processes Governing the Fate and Transport of Radionuclides and Toxic Metals Beneath the Hanford Tank Farms

    International Nuclear Information System (INIS)

    Scott Fendorf; Phil Jardine

    2006-01-01

    The goal of this research was to provide an improved understanding and predictive capability of coupled hydrological and geochemical mechanisms that are responsible for the accelerated migration and immobilization of radionuclides and toxic metals in the vadose zone beneath the Hanford Tank Farms

  16. Photoemission mechanism of water-soluble silver nanoclusters: ligand-to-metal-metal charge transfer vs strong coupling between surface plasmon and emitters.

    Science.gov (United States)

    Chen, Yuting; Yang, Taiqun; Pan, Haifeng; Yuan, Yufeng; Chen, Li; Liu, Mengwei; Zhang, Kun; Zhang, Sanjun; Wu, Peng; Xu, Jianhua

    2014-02-05

    Using carboxylate-protected silver nanoclusters (Ag-carboxylate NCs) as a model, we separately investigated the contribution of the ligand shell and the metal core to understand the nature of photoluminescence of Ag NCs. A new Ag(0)NCs@Ag(I)-carboxylate complex core-shell structural model has been proposed. The emission from the Ag-carboxylate NCs could be attributed to ligand-to-metal-metal charge transfer from Ag(I)-carboxylate complexes (the oxygen atom in the carboxylate ligands to the Ag(I) ions) to the Ag atoms and subsequent radiative relaxation. Additionally, we found that the emission wavelength of the Ag NCs depends on the excitation wavelength implying a strong coupling between surface plasmon and emitter in Ag NCs. The strong coupling between the surface plasmon and the emitter determines the quantum yield and lifetime. The emission mechanism of Ag NCs and its relation to the organic templates and metal cores were clearly clarified. The results should stimulate additional experimental and theoretical research on the molecular-level design of luminescent metal probes for optoelectronics and other applications.

  17. Covering folded shapes

    Directory of Open Access Journals (Sweden)

    Oswin Aichholzer

    2014-05-01

    Full Text Available Can folding a piece of paper flat make it larger? We explore whether a shape S must be scaled to cover a flat-folded copy of itself. We consider both single folds and arbitrary folds (continuous piecewise isometries \\(S\\to\\mathbb{R}^2\\. The underlying problem is motivated by computational origami, and is related to other covering and fixturing problems, such as Lebesgue's universal cover problem and force closure grasps. In addition to considering special shapes (squares, equilateral triangles, polygons and disks, we give upper and lower bounds on scale factors for single folds of convex objects and arbitrary folds of simply connected objects.

  18. MODELS OF PROTEIN FOLDING

    Directory of Open Access Journals (Sweden)

    Unnati Ahluwalia

    2012-12-01

    Full Text Available In an attempt to explore the understanding of protein folding mechanism, various models have been proposed in the literature. Advances in recent experimental and computational techniques rationalized our understanding on some of the fundamental features of the protein folding pathways. The goal of this review is to revisit the various models and outline the essential aspects of the folding reaction.

  19. How the genome folds

    Science.gov (United States)

    Lieberman Aiden, Erez

    2012-02-01

    I describe Hi-C, a novel technology for probing the three-dimensional architecture of whole genomes by coupling proximity-based ligation with massively parallel sequencing. Working with collaborators at the Broad Institute and UMass Medical School, we used Hi-C to construct spatial proximity maps of the human genome at a resolution of 1Mb. These maps confirm the presence of chromosome territories and the spatial proximity of small, gene-rich chromosomes. We identified an additional level of genome organization that is characterized by the spatial segregation of open and closed chromatin to form two genome-wide compartments. At the megabase scale, the chromatin conformation is consistent with a fractal globule, a knot-free conformation that enables maximally dense packing while preserving the ability to easily fold and unfold any genomic locus. The fractal globule is distinct from the more commonly used globular equilibrium model. Our results demonstrate the power of Hi-C to map the dynamic conformations of whole genomes.

  20. Structure of the first representative of Pfam family PF04016 (DUF364) reveals enolase and Rossmann-like folds that combine to form a unique active site with a possible role in heavy-metal chelation

    International Nuclear Information System (INIS)

    Miller, Mitchell D.; Aravind, L.; Bakolitsa, Constantina; Rife, Christopher L.; Carlton, Dennis; Abdubek, Polat; Astakhova, Tamara; Axelrod, Herbert L.; Chiu, Hsiu-Ju; Clayton, Thomas; Deller, Marc C.; Duan, Lian; Feuerhelm, Julie; Grant, Joanna C.; Han, Gye Won; Jaroszewski, Lukasz; Jin, Kevin K.; Klock, Heath E.; Knuth, Mark W.; Kozbial, Piotr; Krishna, S. Sri; Kumar, Abhinav; Marciano, David; McMullan, Daniel; Morse, Andrew T.; Nigoghossian, Edward; Okach, Linda; Reyes, Ron; Bedem, Henry van den; Weekes, Dana; Xu, Qingping; Hodgson, Keith O.; Wooley, John; Elsliger, Marc-André; Deacon, Ashley M.; Godzik, Adam; Lesley, Scott A.; Wilson, Ian A.

    2010-01-01

    The crystal structure of the first representative of DUF364 family reveals a combination of enolase N-terminal-like and C-terminal Rossmann-like folds. Analysis of the interdomain cleft combined with sequence and genome context conservation among homologs, suggests a unique catalytic site likely involved in the synthesis of a flavin or pterin derivative. The crystal structure of Dhaf4260 from Desulfitobacterium hafniense DCB-2 was determined by single-wavelength anomalous diffraction (SAD) to a resolution of 2.01 Å using the semi-automated high-throughput pipeline of the Joint Center for Structural Genomics (JCSG) as part of the NIGMS Protein Structure Initiative (PSI). This protein structure is the first representative of the PF04016 (DUF364) Pfam family and reveals a novel combination of two well known domains (an enolase N-terminal-like fold followed by a Rossmann-like domain). Structural and bioinformatic analyses reveal partial similarities to Rossmann-like methyltransferases, with residues from the enolase-like fold combining to form a unique active site that is likely to be involved in the condensation or hydrolysis of molecules implicated in the synthesis of flavins, pterins or other siderophores. The genome context of Dhaf4260 and homologs additionally supports a role in heavy-metal chelation

  1. Mapping the Galvanic Corrosion of Three Metals Coupled with a Wire Beam Electrode: The Influence of Temperature and Relative Geometrical Position

    OpenAIRE

    Hong Ju; Yuan-Feng Yang; Yun-Fei Liu; Shu-Fa Liu; Jin-Zhuo Duan; Yan Li

    2018-01-01

    The local electrochemical properties of galvanic corrosion for three coupled metals in a desalination plant were investigated with three wire-beam electrodes as wire sensors: aluminum brass (HAl77-2), titanium (TA2), and 316L stainless steel (316L SS). These electrodes were used with artificial seawater at different temperatures. The potential and current–density distributions of the three-metal coupled system are inhomogeneous. The HAl77-2 wire anodes were corroded in the three-metal coupled...

  2. Investigating vibrational anharmonic couplings in cyanide-bridged transition metal mixed valence complexes using two-dimensional infrared spectroscopy

    Science.gov (United States)

    Slenkamp, Karla M.; Lynch, Michael S.; Van Kuiken, Benjamin E.; Brookes, Jennifer F.; Bannan, Caitlin C.; Daifuku, Stephanie L.; Khalil, Munira

    2014-02-01

    Using polarization-selective two-dimensional infrared (2D IR) spectroscopy, we measure anharmonic couplings and angles between the transition dipole moments of the four cyanide stretching (νCN) vibrations found in [(NH3)5RuIIINCFeII(CN)5]- (FeRu) dissolved in D2O and formamide and [(NC)5FeIICNPtIV(NH3)4NCFeII(CN)5]4- (FePtFe) dissolved in D2O. These cyanide-bridged transition metal complexes serve as model systems for studying the role of high frequency vibrational modes in ultrafast photoinduced charge transfer reactions. Here, we focus on the spectroscopy of the νCN modes in the electronic ground state. The FTIR spectra of the νCN modes of the bimetallic and trimetallic systems are strikingly different in terms of frequencies, amplitudes, and lineshapes. The experimental 2D IR spectra of FeRu and FePtFe and their fits reveal a set of weakly coupled anharmonic νCN modes. The vibrational mode anharmonicities of the individual νCN modes range from 14 to 28 cm-1. The mixed-mode anharmonicities range from 2 to 14 cm-1. In general, the bridging νCN mode is most weakly coupled to the radial νCN mode, which involves the terminal CN ligands. Measurement of the relative transition dipole moments of the four νCN modes reveal that the FeRu molecule is almost linear in solution when dissolved in formamide, but it assumes a bent geometry when dissolved in D2O. The νCN modes are modelled as bilinearly coupled anharmonic oscillators with an average coupling constant of 6 cm-1. This study elucidates the role of the solvent in modulating the molecular geometry and the anharmonic vibrational couplings between the νCN modes in cyanide-bridged transition metal mixed valence complexes.

  3. The Coupled Photothermal Reaction and Transport in a Laser Additive Metal Nanolayer Simultaneous Synthesis and Pattering for Flexible Electronics

    Directory of Open Access Journals (Sweden)

    Song-Ling Tsai

    2016-01-01

    Full Text Available The Laser Direct Synthesis and Patterning (LDSP technology has advantages in terms of processing time and cost compared to nanomaterials-based laser additive microfabrication processes. In LDSP, a scanning laser on the substrate surface induces chemical reactions in the reactive liquid solution and selectively deposits target material in a preselected pattern on the substrate. In this study, we experimentally investigated the effect of the processing parameters and type and concentration of the additive solvent on the properties and growth rate of the resulting metal film fabricated by this LDSP technology. It was shown that reactive metal ion solutions with substantial viscosity yield metal films with superior physical properties. A numerical analysis was also carried out the first time to investigate the coupled opto-thermo-fluidic transport phenomena and the effects on the metal film growth rate. To complete the simulation, the optical properties of the LDSP deposited metal film with a variety of thicknesses were measured. The characteristics of the temperature field and the thermally induced flow associated with the moving heat source are discussed. It was shown that the processing temperature range of the LDSP is from 330 to 390 K. A semi-empirical model for estimating the metal film growth rate using this process was developed based on these results. From the experimental and numerical results, it is seen that, owing to the increased reflectivity of the silver film as its thickness increases, the growth rate decreases gradually from about 40 nm at initial to 10 nm per laser scan after ten scans. This self-controlling effect of LDSP process controls the thickness and improves the uniformity of the fabricated metal film. The growth rate and resulting thickness of the metal film can also be regulated by adjustment of the processing parameters, and thus can be utilized for controllable additive nano/microfabrication.

  4. Synchronization of pairwise-coupled, identical, relaxation oscillators based on metal-insulator phase transition devices: A model study

    Science.gov (United States)

    Parihar, Abhinav; Shukla, Nikhil; Datta, Suman; Raychowdhury, Arijit

    2015-02-01

    Computing with networks of synchronous oscillators has attracted wide-spread attention as novel materials and device topologies have enabled realization of compact, scalable and low-power coupled oscillatory systems. Of particular interest are compact and low-power relaxation oscillators that have been recently demonstrated using MIT (metal-insulator-transition) devices using properties of correlated oxides. Further the computational capability of pairwise coupled relaxation oscillators has also been shown to outperform traditional Boolean digital logic circuits. This paper presents an analysis of the dynamics and synchronization of a system of two such identical coupled relaxation oscillators implemented with MIT devices. We focus on two implementations of the oscillator: (a) a D-D configuration where complementary MIT devices (D) are connected in series to provide oscillations and (b) a D-R configuration where it is composed of a resistor (R) in series with a voltage-triggered state changing MIT device (D). The MIT device acts like a hysteresis resistor with different resistances in the two different states. The synchronization dynamics of such a system has been analyzed with purely charge based coupling using a resistive (RC) and a capacitive (CC) element in parallel. It is shown that in a D-D configuration symmetric, identical and capacitively coupled relaxation oscillator system synchronizes to an anti-phase locking state, whereas when coupled resistively the system locks in phase. Further, we demonstrate that for certain range of values of RC and CC, a bistable system is possible which can have potential applications in associative computing. In D-R configuration, we demonstrate the existence of rich dynamics including non-monotonic flows and complex phase relationship governed by the ratios of the coupling impedance. Finally, the developed theoretical formulations have been shown to explain experimentally measured waveforms of such pairwise coupled

  5. PM2.5-bound metal metabolic distribution and coupled lipid abnormality at different developmental windows.

    Science.gov (United States)

    Ku, Tingting; Zhang, Yingying; Ji, Xiaotong; Li, Guangke; Sang, Nan

    2017-09-01

    Atmospheric fine particulate matter (PM 2.5 ) is a serious threat to human health. As a toxicant constituent, metal leads to significant health risks in a population, but exposure to PM 2.5 -bound metals and their biological impacts are not fully understood. In this study, we determined the metal contents of PM 2.5 samples collected from a typical coal-burning city and then investigated the metabolic distributions of six metals (Zn, Pb, Mn, As, Cu, and Cd) following PM 2.5 inhalation in mice in different developmental windows. The results indicate that fine particles were mainly deposited in the lung, but PM 2.5 -bound metals could reach and gather in secondary off-target tissues (the lung, liver, heart and brain) with a developmental window-dependent property. Furthermore, elevations in triglycerides and cholesterol levels in sensitive developmental windows (the young and elderly stages) occurred, and significant associations between metals (Pb, Mn, As and Cd) and cholesterol in the heart, brain, liver and lung were observed. These findings suggest that PM 2.5 inhalation caused selective metal metabolic distribution in tissues with a developmental window-dependent property and that the effects were associated with lipid alterations. This provides a foundation for the underlying systemic toxicity following PM 2.5 exposure based on metal components. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Effects of quantum coupling on the performance of metal-oxide ...

    Indian Academy of Sciences (India)

    Based on the analysis of the three-dimensional Schrödinger equation, the effects of quantum coupling between the transverse and the longitudinal components of channel electron motion on the performance of ballistic MOSFETs have been theoretically investigated by self-consistently solving the coupled ...

  7. Effects of quantum coupling on the performance of metal-oxide ...

    Indian Academy of Sciences (India)

    Figure 1 depicts the potential well in the silicon substrate, the eigenvalues to- gether with the wave functions obtained by self-consistently solving the coupled. Schrödinger–Poisson equations using the finite-difference method by neglecting the quantum coupling (a), when the channel electron velocity of a ballistic MOSFET ...

  8. Optomechanical coupling in phoxonic–plasmonic slab cavities with periodic metal strips

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Tzy-Rong [Department of Mechanical and Mechatronic Engineering, National Taiwan Ocean University, Keelung 20224, Taiwan (China); Institute of Optoelectronic Sciences, National Taiwan Ocean University, Keelung 20224, Taiwan (China); Huang, Yin-Chen [Department of Mechanical and Mechatronic Engineering, National Taiwan Ocean University, Keelung 20224, Taiwan (China); Hsu, Jin-Chen, E-mail: hsujc@yuntech.edu.tw [Department of Mechanical Engineering, National Yunlin University of Science and Technology, Douliou, Yunlin 64002, Taiwan (China)

    2015-05-07

    We theoretically investigate the optomechanical (OM) coupling of submicron cavities formed in one-dimensional phoxonic–plasmonic slabs. The phoxonic–plasmonic slabs are structured by depositing periodic Ag strips onto the top surfaces of dielectric GaAs slabs to produce dual band gaps for both electromagnetic and acoustic waves, thereby inducing the coupling of surface plasmons with photons for tailoring the OM coupling. We quantify the OM coupling by calculating the temporal modulation of the optical resonance wavelength with the acoustic phonon-induced photoelastic (PE) and moving-boundary (MB) effects. We also consider the appearance of a uniform Ag layer on the bottom surface of the slabs to modulate the photonic–plasmonic coupling. The results show that the PE and MB effects can be constructive or destructive in the overall OM coupling, and their magnitudes depend not only on the quality factors of the resonant modes but also on the mode area, mode overlap, and individual symmetries of the photonic–phononic mode pairs. Lowering the mode area could be effective for enhancing the OM coupling of subwavelength photons and phonons. This study introduces possible engineering applications to achieve enhanced interaction between photons and phonons in nanoscale OM devices.

  9. Folded supersymmetry with a twist

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Timothy [Department of Physics, Princeton University,Princeton, NJ 08544 (United States); School of Natural Sciences, Institute for Advanced Study,Princeton, NJ 08540 (United States); Institute of Theoretical Science, University of Oregon,Eugene, OR 97403 (United States); Craig, Nathaniel [Department of Physics, University of California,Santa Barbara, CA 93106 (United States); Lou, Hou Keong [Department of Physics, Princeton University,Princeton, NJ 08544 (United States); Pinner, David [Princeton Center for Theoretical Science, Princeton University,Princeton, NJ 08544 (United States)

    2016-03-30

    Folded supersymmetry (f-SUSY) stabilizes the weak scale against radiative corrections from the top sector via scalar partners whose gauge quantum numbers differ from their Standard Model counterparts. This non-trivial pairing of states can be realized in extra-dimensional theories with appropriate supersymmetry-breaking boundary conditions. We present a class of calculable f-SUSY models that are parametrized by a non-trivial twist in 5D boundary conditions and can accommodate the observed Higgs mass and couplings. Although the distinctive phenomenology associated with the novel folded states should provide strong evidence for this mechanism, the most stringent constraints are currently placed by conventional supersymmetry searches. These models remain minimally fine-tuned in light of LHC8 data and provide a range of both standard and exotic signatures accessible at LHC13.

  10. Estimating FAPAR of Rice Growth Period Using Radiation Transfer Model Coupled with the WOFOST Model for Analyzing Heavy Metal Stress

    Directory of Open Access Journals (Sweden)

    Gaoxiang Zhou

    2017-04-01

    Full Text Available Timely assessment of crop growth conditions under heavy metal pollution is of great significance for agricultural decision-making and estimation of crop productivity. The object of this study is to assess the effects of heavy metal stress on physiological functions of rice through the spatial-temporal analysis of the fraction of absorbed photosynthetically active radiation (FAPAR. The calculation of daily FAPAR is conducted based on a coupled model consisting of the leaf-canopy radiative transfer model and World Food Study Model (WOFOST. These two models are connected by leaf area index (LAI and a fraction of diffused incoming solar radiation (SKYL in the rice growth period. The input parameters of the coupled model are obtained from measured data and GF-1 images. Meanwhile, in order to improve accuracy of FAPAR, the crop growth model is optimized by data assimilation. The validation result shows that the correlation between the simulated FAPAR and the measured data is strong in the rice growth period, with the correlation coefficients being above 7.5 for two areas. The discrepancy of FAPAR between two areas of different stress levels is visualized by spatial-temporal analysis. FAPAR discrepancy starts to appear in the jointing-booting period and experiences a gradual rise, reaching its maximum in the heading-flowering stage. This study suggests that the coupled model, consisting of the leaf-canopy radiative transfer model and the WOFOST model, is able to accurately simulate daily FAPAR during crop growth period and FAPAR can be used as a potential indicator to reflect the impact of heavy metal stress on crop growth.

  11. Strong electron-lattice coupling as the mechanism behind charge density wave transformations in transition-metal dichalcogenides

    Science.gov (United States)

    Gor'kov, Lev P.

    2012-04-01

    We consider a single band of conduction electrons interacting with displacements of the transitional ions. In the classical regime strong enough coupling transforms the harmonic elastic energy for an ion to the one of the well with two deep minima, so that the system is described in terms of Ising spins. Intersite interactions order spins at lower temperatures. Extension to the quantum regime is discussed. Below the charge density wave (CDW) transition the energy spectrum of electrons remains metallic because the structural vector Q and the Fermi surface sizes are not related. Large values of the CDW gap seen in the tunneling experiments correspond to the energy of the minima in the electron-ion two-well complex. The gap is defined through the density of states inside the electronic bands below the CDW transition. We focus mainly on electronic properties of transition-metal dichalcogenides.

  12. Spin-orbit coupling in three-orbital Kanamori impurity model and its relevance for transition-metal oxides

    Science.gov (United States)

    Horvat, Alen; Žitko, Rok; Mravlje, Jernej

    2017-08-01

    We investigate the effects of spin-orbit coupling (SOC) in a three-orbital impurity model with a Kanamori interaction using the numerical renormalization group method. We focus on the impurity occupancy Nd=2 relevant to the dynamical mean-field theory studies of Hund's metals. Depending on the strength of SOC λ , we identify three regimes: the usual Hund's impurity for |λ |λc , and a J =2 impurity for λ <-λc . They all correspond to a Fermi liquid but with very different quasiparticle phase shifts and different physical properties. The crossover between these regimes is controlled by an emergent scale, the orbital Kondo temperature λc=TKorb , that drops with increasing interaction strength. This implies that oxides with strong electronic correlations are more prone to the effects of spin-orbit coupling.

  13. Low speed sliding behavior of metal-ceramic couples at temperatures up to 800 C

    Science.gov (United States)

    Murray, S. F.; Calabrese, Salvadore J.

    1993-05-01

    The objective of this work was to select a small number of alloys with favorable tribological characteristics and suitable high temperature properties, and evaluate their sliding performance against ceramics as a function of temperature. Five candidate alloys were chosen. They included four alloys containing cobalt and molybdenum, or tungsten and a nickel-base superalloy with good high-temperature strength. All of these alloys are known to form oxide films that protect sliding surfaces from damage at high temperature. These metals were slid against five ceramic flats of different compositions in slow speed reciprocating sliding tests. The test geometry was a metal pin sliding against a ceramic flat. Coefficients of friction and wear rates were measured over a temperature range from 25 to 800 C. Material transfer from the metals to the ceramics played a major role in most of the results. In the low-to intermediate-temperature range, the transferred films (with the exception of silicon carbide) coated the ceramic surface and sliding was essentially metal vs the transferred metal film. At higher temperatures, depending on the alloy composition, the transferred films oxidized and provided reasonable low friction and, in some instances, very low wear.

  14. Gold nanoparticle plasmon resonance in near-field coupled Au NPs layer/Al film nanostructure: Dependence on metal film thickness

    Science.gov (United States)

    Yeshchenko, Oleg A.; Kozachenko, Viktor V.; Naumenko, Antonina P.; Berezovska, Nataliya I.; Kutsevol, Nataliya V.; Chumachenko, Vasyl A.; Haftel, Michael; Pinchuk, Anatoliy O.

    2018-05-01

    We study the effects of coupling between plasmonic metal nanoparticles and a thin metal film by using light extinction spectroscopy. A planar monolayer of gold nanoparticles located near an aluminum thin film (thicknesses within the range of 0-62 nm) was used to analyze the coupling between the monolayer and the thin metal film. SPR peak area increase for polymer coated Au NPs, non-monotonical behavior of the peak area for bare Au NPs, as well as red shift and broadening of SPR at the increase of the Al film thickness have been observed. These effects are rationalized as a result of coupling of the layer of Au NPs with Al film through the field of localized surface plasmons in Au NPs that causes the excitation of collective plasmonic gap mode in the nanostructure. An additional mechanism for bare Au NPs is the non-radiative damping of SPR that is caused by the electrical contact between metal NPs and film.

  15. A Fully-Coupled Approach for Modelling Plastic Deformation and Liquid Lubrication in Metal Forming

    DEFF Research Database (Denmark)

    Üstünyagiz, Esmeray; Christiansen, Peter; Nielsen, Chris Valentin

    2016-01-01

    flow formulation which stands on the border line between fluidand solid mechanics and allows treating the lubricants as viscous incompressible (or nearlyincompressible) fluid and the metallic materials as non-Newtonian, high viscous, incompressiblefluids. The presentation is focused on the theoretical......This paper presents a new approach for combined modelling of plastic deformation andliquid lubrication in the contact interfaces between material and tooling in metal forming includingsituations where the lubricant is functioning as a pressure carrier. The approach is an alternative toconventional...... elements with fictitious small stiffness to physical modelling based on a fullycoupled procedure in which the lubricant flow and the plastic deformation of the metallic materialare solved simultaneously. The approach takes advantage of the intrinsic velocity-pressurecharacteristics of the finite element...

  16. Spherical images and inextensible curved folding

    Science.gov (United States)

    Seffen, Keith A.

    2018-02-01

    In their study, Duncan and Duncan [Proc. R. Soc. London A 383, 191 (1982), 10.1098/rspa.1982.0126] calculate the shape of an inextensible surface folded in two about a general curve. They find the analytical relationships between pairs of generators linked across the fold curve, the shape of the original path, and the fold angle variation along it. They present two special cases of generator layouts for which the fold angle is uniform or the folded curve remains planar, for simplifying practical folding in sheet-metal processes. We verify their special cases by a graphical treatment according to a method of Gauss. We replace the fold curve by a piecewise linear path, which connects vertices of intersecting pairs of hinge lines. Inspired by the d-cone analysis by Farmer and Calladine [Int. J. Mech. Sci. 47, 509 (2005), 10.1016/j.ijmecsci.2005.02.013], we construct the spherical images for developable folding of successive vertices: the operating conditions of the special cases in Duncan and Duncan are then revealed straightforwardly by the geometric relationships between the images. Our approach may be used to synthesize folding patterns for novel deployable and shape-changing surfaces without need of complex calculation.

  17. Metal/dielectric thermal interfacial transport considering cross-interface electron-phonon coupling: Theory, two-temperature molecular dynamics, and thermal circuit

    Science.gov (United States)

    Lu, Zexi; Wang, Yan; Ruan, Xiulin

    2016-02-01

    The standard two-temperature equations for electron-phonon coupled thermal transport across metal/nonmetal interfaces are modified to include the possible coupling between metal electrons with substrate phonons. The previous two-temperature molecular dynamics (TT-MD) approach is then extended to solve these equations numerically at the atomic scale, and the method is demonstrated using Cu/Si interface as an example. A key parameter in TT-MD is the nonlocal coupling distance of metal electrons and nonmetal phonons, and here we use two different approximations. The first is based on Overhauser's "joint-modes" concept, while we use an interfacial reconstruction region as the length scale of joint region rather than the phonon mean-free path as in Overhauser's original model. In this region, the metal electrons can couple to the joint phonon modes. The second approximation is the "phonon wavelength" concept where electrons couple to phonons nonlocally within the range of one phonon wavelength. Compared with the original TT-MD, including the cross-interface electron-phonon coupling can slightly reduce the total thermal boundary resistance. Whether the electron-phonon coupling within the metal block is nonlocal or not does not make an obvious difference in the heat transfer process. Based on the temperature profiles from TT-MD, we construct a new mixed series-parallel thermal circuit. We show that such a thermal circuit is essential for understanding metal/nonmetal interfacial transport, while calculating a single resistance without solving temperature profiles as done in most previous studies is generally incomplete. As a comparison, the simple series circuit that neglects the cross-interface electron-phonon coupling could overestimate the interfacial resistance, while the simple parallel circuit in the original Overhauser's model underestimates the total interfacial resistance.

  18. The Laser ablation of a metal foam: The role of electron-phonon coupling and electronic heat diffusivity

    Science.gov (United States)

    Rosandi, Yudi; Grossi, Joás; Bringa, Eduardo M.; Urbassek, Herbert M.

    2018-01-01

    The incidence of energetic laser pulses on a metal foam may lead to foam ablation. The processes occurring in the foam may differ strongly from those in a bulk metal: The absorption of laser light, energy transfer to the atomic system, heat conduction, and finally, the atomistic processes—such as melting or evaporation—may be different. In addition, novel phenomena take place, such as a reorganization of the ligament network in the foam. We study all these processes in an Au foam of average porosity 79% and an average ligament diameter of 2.5 nm, using molecular dynamics simulation. The coupling of the electronic system to the atomic system is modeled by using the electron-phonon coupling, g, and the electronic heat diffusivity, κe, as model parameters, since their actual values for foams are unknown. We show that the foam coarsens under laser irradiation. While κe governs the homogeneity of the processes, g mainly determines their time scale. The final porosity reached is independent of the value of g.

  19. High performance organic photovoltaics with plasmonic-coupled metal nanoparticle clusters.

    Science.gov (United States)

    Park, Hyung Il; Lee, Seunghoon; Lee, Ju Min; Nam, Soo Ah; Jeon, Taewoo; Han, Sang Woo; Kim, Sang Ouk

    2014-10-28

    Performance enhancement of organic photovoltaics using plasmonic nanoparticles has been limited without interparticle plasmon coupling. We demonstrate high performance organic photovoltaics employing gold nanoparticle clusters with controlled morphology as a plasmonic component. Near-field coupling at the interparticle gaps of nanoparticle clusters gives rise to strong enhancement in localized electromagnetic field, which led to the significant improvement of exciton generation and dissociation in the active layer of organic solar cells. A power conversion efficiency of 9.48% is attained by employing gold nanoparticle clusters at the bottom of the organic active layer. This is one of the highest efficiency values reported thus far for the single active layer organic photovoltaics.

  20. Vocal Fold Paralysis

    Science.gov (United States)

    ... decades-long project to develop an electrical stimulation technology to help people avoid having a tracheotomy when both vocal folds are paralyzed. The device, which currently is being tested in animals and people, uses an implanted pacemaker to stimulate ...

  1. Metallic nanoparticle shape and size effects on aluminum oxide-induced enhancement of exciton-plasmon coupling and quantum dot emission

    Energy Technology Data Exchange (ETDEWEB)

    Wing, Waylin J.; Sadeghi, Seyed M., E-mail: seyed.sadeghi@uah.edu; Gutha, Rithvik R.; Campbell, Quinn [Department of Physics, University of Alabama in Huntsville, Huntsville, Alabama 35899 (United States); Mao, Chuanbin [Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, Oklahoma 73019 (United States)

    2015-09-28

    We investigate the shape and size effects of gold metallic nanoparticles on the enhancement of exciton-plasmon coupling and emission of semiconductor quantum dots induced via the simultaneous impact of metal-oxide and plasmonic effects. This enhancement occurs when metallic nanoparticle arrays are separated from the quantum dots by a layered thin film consisting of a high index dielectric material (silicon) and aluminum oxide. Our results show that adding the aluminum oxide layer can increase the degree of polarization of quantum dot emission induced by metallic nanorods by nearly two times, when these nanorods have large aspect ratios. We show when the aspect ratio of these nanorods is reduced to half, the aluminum oxide loses its impact, leading to no improvement in the degree of polarization. These results suggest that a silicon/aluminum oxide layer can significantly enhance exciton-plasmon coupling when quantum dots are in the vicinity of metallic nanoantennas with high aspect ratios.

  2. Oxidative coupling of 1-naphthols over noble and base metal catalysts

    CSIR Research Space (South Africa)

    Maphoru, MV

    2014-01-01

    Full Text Available by the competitive cleavage of one of the two O[BOND]Me bonds at higher temperature. Unpromoted platinum and a range of other metallic catalysts, including gold and Raney nickel, were also found to be active. The products obtained are brightly colored solids...

  3. Analysis of heavy metals in rice bran oil by inductively coupled plasma (ICP) spectrometry

    Science.gov (United States)

    Rice is one of the most important staple crops in the world. Nevertheless, health-conscious consumers have expressed concern regarding the presence of heavy metals, specifically arsenic, in rice. The United Nations Food and Agriculture Organization (UNFAO) limits the arsenic concentration at 0.2 mg/...

  4. Rapid lead isotope analysis of archaeological metals by multiple-collector inductively coupled plasma mass spectrometry

    DEFF Research Database (Denmark)

    Baker, J.A.; Stos, S.; Waight, Tod Earle

    2006-01-01

    Lead isotope ratios in archaeological silver and copper were determined by MC-ICPMS using laser ablation and bulk dissolution without lead purification. Laser ablation results on high-lead metals and bulk solution analyses on all samples agree within error of TIMS data, suggesting that problems...

  5. Plasmon hybridization in silver nanoislands as semishell arrays coupled to a thin metallic film

    DEFF Research Database (Denmark)

    Maaroof, Abbas; Nygaard, Jens Vinge; Sutherland, Duncan S

    2011-01-01

    We obtained experimentally strong plasmon interactions between localized surface plasmon with delocalized surface plasmon polaritons in a new nanosystem of silver semishells island film arrays arranged as a closed-packing structure coupled to an adjacent thin silver film. We show that plasmon...

  6. The Manganese-Catalyzed Cross-Coupling Reaction and the Influence of Trace Metals

    DEFF Research Database (Denmark)

    Santilli, Carola; Beigbaghlou, Somayyeh Sarvi; Ahlburg, Andreas

    2017-01-01

    The substrate scope of the MnCl2-catalyzed cross-coupling between aryl halides and Grignard reagents has been extended to several methyl-substituted aryl iodides by performing the reaction at elevated temperature in a microwave oven. A radical clock experiment revealed the presence of an aryl...

  7. Improving the calculation of electron paramagnetic resonance hyperfine coupling tensors for d-block metals

    DEFF Research Database (Denmark)

    Hedegård, Erik Donovan; Kongsted, Jacob; Sauer, Stephan P. A.

    2012-01-01

    and obtained a set of basis functions for the elements Sc–Zn, which were saturated with respect to both the Fermi contact and spin-dipolar components of the hyperfine coupling tensor [Hedeg°ard et al., J. Chem. Theory Comput., 2011, 7, pp. 4077-4087]. Furthermore, a contraction scheme was proposed leading...

  8. Methane coupling reaction in an oxy-steam stream through an OH radical pathway by using supported alkali metal catalysts

    KAUST Repository

    Liang, Yin

    2014-03-24

    A universal reaction mechanism involved in the oxidative coupling of methane (OCM) is demonstrated under oxy-steam conditions using alkali-metal-based catalysts. Rigorous kinetic measurements indicated a reaction mechanism that is consistent with OH radical formation from a H 2O-O2 reaction followed by C-H activation in CH 4 with an OH radical. Thus, the presence of water enhances both the CH4 conversion rate and the C2 selectivity. This OH radical pathway that is selective for the OCM was observed for the catalyst without Mn, which suggests clearly that Mn is not the essential component in a selective OCM catalyst. The experiments with different catalyst compositions revealed that the OH.-mediated pathway proceeded in the presence of catalysts with different alkali metals (Na, K) and different oxo anions (W, Mo). This difference in catalytic activity for OH radical generation accounts for the different OCM selectivities. As a result, a high C2 yield is achievable by using Na2WO4/SiO2, which catalyzes the OH.-mediated pathway selectively. Make it methane: A universal reaction mechanism involved in the oxidative coupling of methane is demonstrated under oxy-stream conditions by using alkali-metal-based catalysts. Rigorous kinetic measurements indicated a reaction mechanism that is consistent with OH radical formation from an H2O-O2 reaction, followed by C-H activation in CH4 with an OH radical. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Commercial liquid-metal MHD conversion systems coupled to LMFBR and coal-fired fluidized bed combustors

    International Nuclear Information System (INIS)

    Amend, W.E.; Brunsvold, A.; Pierson, E.S.

    1975-01-01

    The constraints imposed on two-phase liquid-metal MHD (LMMHD) when employed in commercial power plants with practical heat sources have not previously been studied. The coupling of a LMMHD power system with an LMFBR and a coal-fired fluidized bed combustor are considered. Two MHD systems are considered. The first is a dual cycle where heat is added to both the liquid metal and the gas, and the gas may expand through a gas turbine after the MHD generator. The second system, a binary cycle, differs in that a significant portion of the sensible heat in the gas entering the compression loop is converted to useful power in a steam bottoming cycle. The effect of liquid-metal vapor carry-over into the gas loop is included. The couplings of the LMMHD system with the heat sources and with the steam plants were studied in depth. The results of the study of each interface are presented parametrically for each heat source and energy conversion system. Operating points have been selected and the complete schematic of each system considered is presented along with all thermodynamic state points and fluid flow rates. All system parameters and component efficiencies were selected to be consistent with near term technology and good engineering design principles. These criteria yielded a system performance of 37 percent for an LMFBR operating with a maximum reactor coolant temperature of 1200 0 F when the pure LMMHD energy converter was used. A LMMHD/steam binary cycle is shown to be capable of achieving a thermal efficiency of 44.8 percent when used with the same heat source. Results with the coal fluidized bed combustor as a heat source show even higher performance levels (about 50 percent efficiency) since the maximum cycle temperature is increased

  10. On-line system for preconcentration and determination of metals in vegetables by Inductively Coupled Plasma Optical Emission Spectrometry

    International Nuclear Information System (INIS)

    Bezerra, Marcos A.; Santos, Walter N.L. dos; Lemos, Valfredo A.; Korn, Maria das Gracas A.; Ferreira, Sergio L.C.

    2007-01-01

    A procedure has been developed for the simultaneous determination of trace amounts of cadmium, copper, chromium, nickel and lead in digested vegetable samples. The method involves solid-phase extraction of the metals using a minicolumn of Amberlite XAD-4 modified with dihydroxybenzoic acid (DHB) and detection by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). The elution of the metals from minicolumn was performed with 1.0 mol L -1 hydrochloric acid. Variables associated with flow preconcentration system performance, such as pH, buffer concentration, eluent concentration and sampling flow rate, were optimized. The developed procedure provides enrichment factors of 100, 72, 16, 91 and 53, for cadmium, copper, chromium, nickel and lead, respectively. Detection limits (3σ B ) were 0.02 (Cd), 0.23 (Cu), 0.58 (Cr), 0.060 (Ni) and 0.54 (Pb) μg L -1 . The procedure was applied for determination of metals in samples of guarana and cabbage. The accuracy of the method was checked by the analysis of a certified reference material (NIST 1571, Orchard leaves). Results found were in agreement with certified values

  11. Strong electron-hole symmetric Rashba spin-orbit coupling in graphene/monolayer transition metal dichalcogenide heterostructures

    Science.gov (United States)

    Yang, Bowen; Lohmann, Mark; Barroso, David; Liao, Ingrid; Lin, Zhisheng; Liu, Yawen; Bartels, Ludwig; Watanabe, Kenji; Taniguchi, Takashi; Shi, Jing

    2017-07-01

    Despite its extremely weak intrinsic spin-orbit coupling (SOC), graphene has been shown to acquire considerable SOC by proximity coupling with exfoliated transition metal dichalcogenides (TMDs). Here we demonstrate strong induced Rashba SOC in graphene that is proximity coupled to a monolayer TMD film, Mo S2 or WS e2 , grown by chemical-vapor deposition with drastically different Fermi level positions. Graphene/TMD heterostructures are fabricated with a pickup-transfer technique utilizing hexagonal boron nitride, which serves as a flat template to promote intimate contact and therefore a strong interfacial interaction between TMD and graphene as evidenced by quenching of the TMD photoluminescence. We observe strong induced graphene SOC that manifests itself in a pronounced weak-antilocalization (WAL) effect in the graphene magnetoconductance. The spin-relaxation rate extracted from the WAL analysis varies linearly with the momentum scattering time and is independent of the carrier type. This indicates a dominantly Dyakonov-Perel spin-relaxation mechanism caused by the induced Rashba SOC. Our analysis yields a Rashba SOC energy of ˜1.5 meV in graphene/WS e2 and ˜0.9 meV in graphene/Mo S2 . The nearly electron-hole symmetric nature of the induced Rashba SOC provides a clue to possible underlying SOC mechanisms.

  12. Mapping the Galvanic Corrosion of Three Metals Coupled with a Wire Beam Electrode: The Influence of Temperature and Relative Geometrical Position

    Directory of Open Access Journals (Sweden)

    Hong Ju

    2018-02-01

    Full Text Available The local electrochemical properties of galvanic corrosion for three coupled metals in a desalination plant were investigated with three wire-beam electrodes as wire sensors: aluminum brass (HAl77-2, titanium (TA2, and 316L stainless steel (316L SS. These electrodes were used with artificial seawater at different temperatures. The potential and current–density distributions of the three-metal coupled system are inhomogeneous. The HAl77-2 wire anodes were corroded in the three-metal coupled system. The TA2 wires acted as cathodes and were protected; the 316L SS wires acted as secondary cathodes. The temperature and electrode arrangement have important effects on the galvanic corrosion of the three-metal coupled system. The corrosion current of the HAl77-2 increased with temperature indicating enhanced anode corrosion at higher temperature. In addition, the corrosion of HAl77-2 was more significant when the HAl77-2 wires were located in the middle of the coupled system than with the other two metal arrangement styles.

  13. Mapping the Galvanic Corrosion of Three Metals Coupled with a Wire Beam Electrode: The Influence of Temperature and Relative Geometrical Position.

    Science.gov (United States)

    Ju, Hong; Yang, Yuan-Feng; Liu, Yun-Fei; Liu, Shu-Fa; Duan, Jin-Zhuo; Li, Yan

    2018-02-28

    The local electrochemical properties of galvanic corrosion for three coupled metals in a desalination plant were investigated with three wire-beam electrodes as wire sensors: aluminum brass (HAl77-2), titanium (TA2), and 316L stainless steel (316L SS). These electrodes were used with artificial seawater at different temperatures. The potential and current-density distributions of the three-metal coupled system are inhomogeneous. The HAl77-2 wire anodes were corroded in the three-metal coupled system. The TA2 wires acted as cathodes and were protected; the 316L SS wires acted as secondary cathodes. The temperature and electrode arrangement have important effects on the galvanic corrosion of the three-metal coupled system. The corrosion current of the HAl77-2 increased with temperature indicating enhanced anode corrosion at higher temperature. In addition, the corrosion of HAl77-2 was more significant when the HAl77-2 wires were located in the middle of the coupled system than with the other two metal arrangement styles.

  14. Mapping the Galvanic Corrosion of Three Metals Coupled with a Wire Beam Electrode: The Influence of Temperature and Relative Geometrical Position

    Science.gov (United States)

    Liu, Yun-Fei; Liu, Shu-Fa; Duan, Jin-Zhuo

    2018-01-01

    The local electrochemical properties of galvanic corrosion for three coupled metals in a desalination plant were investigated with three wire-beam electrodes as wire sensors: aluminum brass (HAl77-2), titanium (TA2), and 316L stainless steel (316L SS). These electrodes were used with artificial seawater at different temperatures. The potential and current–density distributions of the three-metal coupled system are inhomogeneous. The HAl77-2 wire anodes were corroded in the three-metal coupled system. The TA2 wires acted as cathodes and were protected; the 316L SS wires acted as secondary cathodes. The temperature and electrode arrangement have important effects on the galvanic corrosion of the three-metal coupled system. The corrosion current of the HAl77-2 increased with temperature indicating enhanced anode corrosion at higher temperature. In addition, the corrosion of HAl77-2 was more significant when the HAl77-2 wires were located in the middle of the coupled system than with the other two metal arrangement styles. PMID:29495617

  15. Diffusion Couple Alloying of Refractory Metals in Austenitic and Ferritic/Martensitic Steels

    Science.gov (United States)

    2012-03-01

    temperature (DBTT) and lower upper shelf energy (USE) obtained via a Charpy impact test (austenitic steels , however, do not experience DBTT) as seen in...ALLOYING OF REFRACTORY METALS IN AUSTENITIC AND FERRITIC/MARTENSITIC STEELS by Alexander L. McGinnis March 2012 Thesis Advisor: Luke...Ferritic/Martensitic Steels 5. FUNDING NUMBERS 6. AUTHOR(S) Alexander L. McGinnis 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Naval

  16. Contribution to the theoretical study of metallic systems containing rare earths: hyperfine interactions and exchange coupling

    International Nuclear Information System (INIS)

    Troper, A.

    1978-01-01

    A theoretical study involving rare earth impurities, which were embedded in transition metals (s-p or noble), from the point of view of the hyperfine interactions is presented. A model was created to describe a d-resonance (Anderson-Moriya) acting on a s-p conduction band which was strongly perturbed by a slater-koster potential, used to describe the rare earths which were diluted in matrices of transition elements. (author)

  17. Tuning the metal-insulator transition in manganite films through surface exchange coupling with magnetic nanodots.

    Science.gov (United States)

    Ward, T Z; Gai, Z; Xu, X Y; Guo, H W; Yin, L F; Shen, J

    2011-04-15

    In strongly correlated electronic systems, the global transport behavior depends sensitively on spin ordering. We show that spin ordering in manganites can be controlled by depositing isolated ferromagnetic nanodots at the surface. The exchange field at the interface is tunable with nanodot density and makes it possible to overcome dimensionality and strain effects in frustrated systems to greatly increasing the metal-insulator transition and magnetoresistance. These findings indicate that electronic phase separation can be controlled by the presence of magnetic nanodots.

  18. Electromembrane extraction of heavy metal cations followed by capillary electrophoresis with capacitively coupled contactless conductivity detection

    Czech Academy of Sciences Publication Activity Database

    Kubáň, Pavel; Strieglerová, Lenka; Gebauer, Petr; Boček, Petr

    2011-01-01

    Roč. 32, č. 9 (2011), s. 1025-1032 ISSN 0173-0835 R&D Projects: GA ČR GA203/08/1536; GA ČR GAP206/10/1219; GA AV ČR IAA400310703 Institutional research plan: CEZ:AV0Z40310501 Keywords : capillary electrophoresis * electromembrane extraction * heavy metal cations Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.303, year: 2011

  19. Vocal Fold Collision Modeling

    DEFF Research Database (Denmark)

    Granados, Alba; Brunskog, Jonas; Misztal, M. K.

    2015-01-01

    When vocal folds vibrate at normal speaking frequencies, collisions occurs. The numerics and formulations behind a position-based continuum model of contact is an active field of research in the contact mechanics community. In this paper, a frictionless three-dimensional finite element model...... of the vocal fold collision is proposed, which incorporates different procedures used in contact mechanics and mathematical optimization theories. The penalty approach and the Lagrange multiplier method are investigated. The contact force solution obtained by the penalty formulation is highly dependent...

  20. Electrochemical Behaviour and Galvanic Effects of Titanium Implants Coupled to Metallic Suprastructures in Artificial Saliva

    Directory of Open Access Journals (Sweden)

    Ana Mellado-Valero

    2018-01-01

    Full Text Available The aim of the present study is to analyze the electrochemical behavior of five different dental alloys: two cobalt-chromium alloys (CoCr and CoCr-c, one nickel-chromium-titanium alloy (NiCrTi, one gold-palladium alloy (Au, and one titanium alloy (Ti6Al4V, and the galvanic effect when they are coupled to titanium implants (TiG2. It was carried out by electrochemical techniques (open circuit measurements, potentiodynamic curves and Zero-Resistance Ammetry in artificial saliva (AS, with and without fluorides in different acidic conditions. The studied alloys are spontaneously passivated, but NiCrTi alloy has a very narrow passive domain and losses its passivity in presence of fluorides, so is not considered as a good option for implant superstructures. Variations of pH from 6.5 to 3 in artificial saliva do not change the electrochemical behavior of Ti, Ti6Al4V, and CoCr alloys, and couples, but when the pH of the artificial saliva is below 3.5 and the fluoride content is 1000 ppm Ti and Ti6Al4V starts actively dissolving, and CoCr-c superstructures coupled to Ti show acceleration of corrosion due to galvanic effects. Thus, NiCrTi is not recommended for implant superstructures because of risk of Ni ion release to the body, and fluorides should be avoided in acidic media because Ti, Ti6Al4V, and CoCr-c superstructures show galvanic corrosion. The best combinations are Ti/Ti6Al4V and Ti/CoCr as alternative of noble gold alloys.

  1. Electrochemical Behaviour and Galvanic Effects of Titanium Implants Coupled to Metallic Suprastructures in Artificial Saliva

    Science.gov (United States)

    Mellado-Valero, Ana; Igual Muñoz, Anna; Guiñón Pina, Virginia

    2018-01-01

    The aim of the present study is to analyze the electrochemical behavior of five different dental alloys: two cobalt-chromium alloys (CoCr and CoCr-c), one nickel-chromium-titanium alloy (NiCrTi), one gold-palladium alloy (Au), and one titanium alloy (Ti6Al4V), and the galvanic effect when they are coupled to titanium implants (TiG2). It was carried out by electrochemical techniques (open circuit measurements, potentiodynamic curves and Zero-Resistance Ammetry) in artificial saliva (AS), with and without fluorides in different acidic conditions. The studied alloys are spontaneously passivated, but NiCrTi alloy has a very narrow passive domain and losses its passivity in presence of fluorides, so is not considered as a good option for implant superstructures. Variations of pH from 6.5 to 3 in artificial saliva do not change the electrochemical behavior of Ti, Ti6Al4V, and CoCr alloys, and couples, but when the pH of the artificial saliva is below 3.5 and the fluoride content is 1000 ppm Ti and Ti6Al4V starts actively dissolving, and CoCr-c superstructures coupled to Ti show acceleration of corrosion due to galvanic effects. Thus, NiCrTi is not recommended for implant superstructures because of risk of Ni ion release to the body, and fluorides should be avoided in acidic media because Ti, Ti6Al4V, and CoCr-c superstructures show galvanic corrosion. The best combinations are Ti/Ti6Al4V and Ti/CoCr as alternative of noble gold alloys. PMID:29361767

  2. Coupling meteorology, metal concentrations, and Pb isotopes for source attribution in archived precipitation samples.

    Science.gov (United States)

    Graney, Joseph R; Landis, Matthew S

    2013-03-15

    A technique that couples lead (Pb) isotopes and multi-element concentrations with meteorological analysis was used to assess source contributions to precipitation samples at the Bondville, Illinois USA National Trends Network (NTN) site. Precipitation samples collected over a 16month period (July 1994-October 1995) at Bondville were parsed into six unique meteorological flow regimes using a minimum variance clustering technique on back trajectory endpoints. Pb isotope ratios and multi-element concentrations were measured using high resolution inductively coupled plasma-sector field mass spectrometry (ICP-SFMS) on the archived precipitation samples. Bondville is located in central Illinois, ~250km downwind from smelters in southeast Missouri. The Mississippi Valley Type ore deposits in Missouri provided a unique multi-element and Pb isotope fingerprint for smelter emissions which could be contrasted to industrial emissions from the Chicago and Indianapolis urban areas (~125km north and east, of Bondville respectively) and regional emissions from electric utility facilities. Differences in Pb isotopes and element concentrations in precipitation corresponded to flow regime. Industrial sources from urban areas, and thorogenic Pb from coal use, could be differentiated from smelter emissions from Missouri by coupling Pb isotopes with variations in element ratios and relative mass factors. Using a three endmember mixing model based on Pb isotope ratio differences, industrial processes in urban airsheds contributed 56±19%, smelters in southeast Missouri 26±13%, and coal combustion 18±7%, of the Pb in precipitation collected in Bondville in the mid-1990s. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. Spin relaxation near the metal-insulator transition: dominance of the Dresselhaus spin-orbit coupling.

    Science.gov (United States)

    Intronati, Guido A; Tamborenea, Pablo I; Weinmann, Dietmar; Jalabert, Rodolfo A

    2012-01-06

    We identify the Dresselhaus spin-orbit coupling as the source of the dominant spin-relaxation mechanism in the impurity band of a wide class of n-doped zinc blende semiconductors. The Dresselhaus hopping terms are derived and incorporated into a tight-binding model of impurity sites, and they are shown to unexpectedly dominate the spin relaxation, leading to spin-relaxation times in good agreement with experimental values. This conclusion is drawn from two complementary approaches: an analytical diffusive-evolution calculation and a numerical finite-size scaling study of the spin-relaxation time.

  4. J(Si,H) Coupling Constants in Nonclassical Transition-Metal Silane Complexes.

    Science.gov (United States)

    Scherer, Wolfgang; Meixner, Petra; Batke, Kilian; Barquera-Lozada, José E; Ruhland, Klaus; Fischer, Andreas; Eickerling, Georg; Eichele, Klaus

    2016-09-12

    We will outline that the sign and magnitude of J(Si,H) coupling constants provide a highly sensitive tool to measure the extent of Si-H bond activation in nonclassical silane complexes. Up to now, this structure-property relationship was obscured by erroneous J(Si,H) sign determinations in the literature. These new findings also help to identify the salient control parameters of the Si-H bond activation process in nonclassical silane complexes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Determination of some inorganic metals in edible vegetable oils by inductively coupled plasma atomic emission spectroscopy (ICP-AES

    Directory of Open Access Journals (Sweden)

    Musa Özcan, M.

    2008-09-01

    Full Text Available Seventeen edible vegetable oils were analyzed spectrometrically for their metal (Cu, Fe, Mn, Co, Cr, Pb, Cd, Ni, and Zn contents. Toxic metals in edible vegetable oils were determined by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES. The highest metal concentrations were measured as 0.0850, 0.0352, 0.0220, 0.0040, 0.0010, 0.0074, 0.0045, 0.0254 and 0.2870 mg/kg for copper in almond oil, for iron in corn oil-(c, for manganese in soybean oil, for cobalt in sunflower oil-(b and almond oil, for chromium in almond oil, for lead in virgin olive oil, for cadmium in sunflower oil-(e, for nickel almond oil and for zinc in almond oil respectively. The method for determining toxic metals in edible vegetable oils by using ICP-AES is discussed. The metals were extracted from low quantities of oil (2-3 g with a 10% nitric acid solution. The extracted metal in acid solution can be injected into the ICPAES. The proposed method is simple and allows the metals to be determined in edible vegetable oils with a precision estimated below 10% relative standard deviation (RSD for Cu, 5% for Fe, 15% for Mn, 8% for Co, 10% for Cr, 20% for Pb, 5% for Cd, 16% for Ni and 11% for Zn.En este estudio se analizó espectrométricamente el contenido en metales (Cu, Fe, Mn, Co, Cr, Pb, Cd, Ni, and Zn de 17 aceites vegetales comestibles mediante ICP-AES. Las concentaciones más elevadas se encontraron para el cobre en el aceite de almendra (0.0850 mg/kg, para el hierro en el aceite de maiz(c,(0.0352 mg/kg, para el manganeso en el aceite de soja (0.0220 mg/kg, para el cobalto en el aceite de girasol (b (0.0040 mg/kg, para el cromo en el aceite de almendra (0.0010 mg/kg, para el plomo en el aceite de oliva virgen (0.0074 mg/kg, para el cadmio en el aceite de girasol (e (0.0045 mg/kg, para el niquel en el aceite de almendra (0.0254 mg/kg y para el zincen el aceite de almendra (0.2870 mg/kg. Los metales se extrajeron a partir de bajas cantidades de aceite (2-3 g, con

  6. Electrically tunable strong light-matter coupling in a transition metal dichalcogenide monolayer embedded in a plasmonic crystal cavity

    Science.gov (United States)

    Scuri, Giovanni; Zhou, You; High, Alexander; Dibos, Alan; de Greve, Kristiaan; Polking, Mark; Juaregui, Luis; Wild, Dominik; Joe, Andrew; Pistunova, Kateryna; Lukin, Mikhail; Kim, Philip; Park, Hongkun

    Two-dimensional transition-metal dichalcogenide (TMDC) monolayers exhibit direct bandgap excitons with large binding energy. The optical response of TMDCs is electrically tunable over a broad wavelength range, making these 2D materials promising candidates for optoelectronic devices. In this work, we enhance exciton-plasmon coupling by embedding a single layer of tungsten diselenide (WSe2) into a plasmonic crystal cavity, which confines surface plasmon polaritons in an analogous manner to photonic crystal cavities. We observe strong light-matter interactions and the formation of microcavity polaritons when the cavity mode is on resonance with the exciton absorption in WSe2. Using the electrostatically controllable response of such excitons, we also demonstrate tunable vacuum Rabi splitting in such a system.

  7. Trace metal analysis of road dust by inductively coupled plasma mass spectrometry

    International Nuclear Information System (INIS)

    Powell, M.J.; Liu, L.; Gnanalingham, N.; Peters, L.

    2000-01-01

    Dust from roads in an air impingement zone close to anthropogenic sources of air pollutants can be a concern for people living in the immediate vicinity. The Ministry of the Environment (MOE) has conducted a case study to monitor the concentration of uranium, strontium, thorium and arsenic in road dust from one such area. A method for the analysis of road dust by inductively coupled plasma mass spectrometry (ICP-MS) has been developed with detection limits in the ng/1 range. A digestion technique has been developed by conducting experiments using single and combinations of acids in open-vessel wet digestions. Accuracy has been determined by the use of matrix representative certified reference materials (CRMs). Digestion precision was determined by elemental concentration measurements of the most representative CRM through replicates. Spike recovery data were from 95% to 110% for all elements, and inter-method comparison studies between hydride generation atomic absorption spectrometry (AAS) inductively coupled plasma atomic emission spectrometry (ICP-AES) and ICP-MS for arsenic and strontium show good agreement. (author)

  8. Folds and Etudes

    Science.gov (United States)

    Bean, Robert

    2007-01-01

    In this article, the author talks about "Folds" and "Etudes" which are images derived from anonymous typing exercises that he found in a used copy of "Touch Typing Made Simple". "Etudes" refers to the musical tradition of studies for a solo instrument, which is a typewriter. Typing exercises are repetitive attempts to type words and phrases…

  9. Folding worlds between pages

    CERN Document Server

    Meier, Matthias

    2010-01-01

    "We all remember pop-up books form our childhood. As fascinated as we were back then, we probably never imagined how much engineering know-how went into these books. Pop-up engineer Anton Radevsky has even managed to fold a 27-kilometre particle accelerator into a book" (4 pages)

  10. Preconcentration of heavy metals on activated carbon and their determination in fruits by inductively coupled plasma optical emission spectrometry.

    Science.gov (United States)

    Feist, Barbara; Mikula, Barbara

    2014-03-15

    A method of separation and preconcentration of cadmium, cobalt, copper, nickel, lead, and zinc at trace level using activated carbon is proposed. Activated carbon with the adsorbed trace metals was mineralised using a high-pressure microwave mineraliser. The heavy metals were determined after preconcentration by inductively coupled plasma optical emission spectrometry (ICP-OES). The influence of several parameters, such as pH, sorbent mass, shaking time was examined. Moreover, effects of inorganic matrix on recovery of the determined elements were studied. The experiment shows that foreign ions did not influence recovery of the determined elements. The detection limits (DL) of Cd, Co, Cu, Ni, Pb, and Zn were 0.17, 0.19, 1.60, 2.60, 0.92 and 1.50 μg L(-)(1), respectively. The recovery of the method for the determined elements was better than 95% with relative standard deviation from 1.3% to 3.7%. The preconcentration factor was 80. The proposed method was applied for determination of Cd, Co, Cu, Ni, Pb, and Zn in fruits materials. Accuracy of the proposed method was verified using certified reference material (NCS ZC85006 Tomato). Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Analysis of Mineral and Heavy Metal Content of Some Commercial Fruit Juices by Inductively Coupled Plasma Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Adriana Dehelean

    2013-01-01

    Full Text Available The presence of potentially toxic elements and compounds in foodstuffs is of intense public interest and thus requires rapid and accurate methods to determine the levels of these contaminants. Inductively coupled plasma mass spectrometry is a powerful tool for the determination of metals and nonmetals in fruit juices. In this study, 21 commercial fruit juices (apple, peach, apricot, orange, kiwi, pear, pineapple, and multifruit present on Romanian market were investigated from the heavy metals and mineral content point of view by ICP-MS. Our obtained results were compared with those reported in literature and also with the maximum admissible limit in drinking water by USEPA and WHO. For Mn the obtained values exceeded the limits imposed by these international organizations. Co, Cu, Zn, As, and Cd concentrations were below the acceptable limit for drinking water for all samples while the concentrations of Ni and Pb exceeded the limits imposed by USEPA and WHO for some fruit juices. The results obtained in this study are comparable to those found in the literature.

  12. Rapid classification of heavy metal-exposed freshwater bacteria by infrared spectroscopy coupled with chemometrics using supervised method

    Science.gov (United States)

    Gurbanov, Rafig; Gozen, Ayse Gul; Severcan, Feride

    2018-01-01

    Rapid, cost-effective, sensitive and accurate methodologies to classify bacteria are still in the process of development. The major drawbacks of standard microbiological, molecular and immunological techniques call for the possible usage of infrared (IR) spectroscopy based supervised chemometric techniques. Previous applications of IR based chemometric methods have demonstrated outstanding findings in the classification of bacteria. Therefore, we have exploited an IR spectroscopy based chemometrics using supervised method namely Soft Independent Modeling of Class Analogy (SIMCA) technique for the first time to classify heavy metal-exposed bacteria to be used in the selection of suitable bacteria to evaluate their potential for environmental cleanup applications. Herein, we present the powerful differentiation and classification of laboratory strains (Escherichia coli and Staphylococcus aureus) and environmental isolates (Gordonia sp. and Microbacterium oxydans) of bacteria exposed to growth inhibitory concentrations of silver (Ag), cadmium (Cd) and lead (Pb). Our results demonstrated that SIMCA was able to differentiate all heavy metal-exposed and control groups from each other with 95% confidence level. Correct identification of randomly chosen test samples in their corresponding groups and high model distances between the classes were also achieved. We report, for the first time, the success of IR spectroscopy coupled with supervised chemometric technique SIMCA in classification of different bacteria under a given treatment.

  13. Comparison of rigorous coupled-wave approach and finite element method for photovoltaic devices with periodically corrugated metallic backreflector.

    Science.gov (United States)

    Solano, Manuel E; Faryad, Muhammad; Lakhtakia, Akhlesh; Monk, Peter B

    2014-10-01

    Optimal design of photovoltaic devices with a periodically corrugated metallic backreflector requires a rapid and reliable way to simulate the optical characteristics for wide ranges of wavelengths and angles of incidence. Two independent numerical techniques are needed for confidence in numerical results. We compared the rigorous coupled-wave approach (RCWA) and the finite element method (FEM), the former being fast and flexible, but the latter having predictable convergence even for discontinuous constitutive properties. Depending on the shape of the corrugation and the constitutive properties of the metal and dielectric materials making up the device, both techniques can exhibit slow convergence rates for p-polarized light. The chosen model problem in this paper is of this type. As rapid spatial variations of the fields are the underlying cause, suitable selective refinement of the FEM mesh can overcome this slow convergence. Therefore, it would be desirable to have a self-adaptive scheme for choosing the mesh in the FEM. This will slow down the algorithm but give a reliable way to check the RCWA results.

  14. FLOW INJECTION ANALYSIS SYSTEM COUPLED WITH ICP-EOS FOR DETERMINATION OF SOME METALLIC ELEMENTS IN DRINKING WATER

    Directory of Open Access Journals (Sweden)

    Cristina Dinu

    2009-06-01

    Full Text Available The European Drinking Water Directive (98/83/EC, transposed in Romanian Legislation as Low 458/2002, amended by Low 311/2004, imposes the limit of concentration for metallic elements in water intended for human consumption. The toxic metals arsenic and selenium are among these elements and the limit value is 10 μg/L. In the paper there are presented the working conditions for determination of As and Se from drinking water using modern techniques based on the fl ow injection-hydride generation with the inductively coupled plasma atomic emission spectrometry (FIAS-ICP-EOS. The analyses were performed on Optima 5300 DV Perkin Elmer equipment with FIAS 400 Flow Injection System, Perkin Elmer type. For the hydride generation two types of solution were used: 10% (v/v HCl as a carrier solution and 0.2 % NaBH4 in 0.05%NaOH solution as a reducing agent [1]. The treatment step of the samples and standard solutions consisted in reducing with mixed solutions of KI and ascorbic acid in acidic condition (HCl for As and only with HCl and high temperature for Se [2,3]. The paper contains the characteristic parameters of the methods, such as: low detection limit, quantifi cation limit, repeatability, precision, recovery, which were evaluated using Certifi ed Reference Materials for each element.

  15. Removal of heavy-metal pollutants from ground water using a reverse-osmosis/coupled-transport hybrid system

    International Nuclear Information System (INIS)

    Edlund, D.J.; Friesen, D.T.; Ray, R.J.; Scholfield, R.W.

    1993-01-01

    Two membrane processes - reverse osmosis (RO) and coupled transport (CT) - are useful in removing heavy metals from aqueous solutions and producing purified water. Each process has advantages. RO produces clean water reliably and relatively inexpensively. However, the pollutants are removed nonselectively and cannot be appreciably concentrated. CT removes pollutants selectively and can concentrate them by several orders of magnitude, but CT suffers from limited reliability and performs poorly at low pollutant concentrations. By combining these two unit processes in a hybrid process, it is possible to capitalize on the advantages of each process and to minimize their disadvantages. The RO/CT hybrid process the authors are developing removes more than 98% of the uranium and chromium in a contaminated groundwater stream - reducing concentrations of each pollutant to less than 100 ppb. These pollutants are simultaneously recovered as a concentrate at metal-ion concentrations greater than 1 wt% in relatively pure form. The hybrid process promises to be reliable and to reduce treatment costs below that for costs if either CT or RO were used alone. Even more importantly, the high selectivity of the hybrid process minimizes the volume of waste requiring disposal

  16. Direct Structural Identification of Gas Induced Gate-Opening Coupled with Commensurate Adsorption in a Microporous Metal-Organic Framework.

    Science.gov (United States)

    Banerjee, Debasis; Wang, Hao; Plonka, Anna M; Emge, Thomas J; Parise, John B; Li, Jing

    2016-08-08

    Gate-opening is a unique and interesting phenomenon commonly observed in flexible porous frameworks, where the pore characteristics and/or crystal structures change in response to external stimuli such as adding or removing guest molecules. For gate-opening that is induced by gas adsorption, the pore-opening pressure often varies for different adsorbate molecules and, thus, can be applied to selectively separate a gas mixture. The detailed understanding of this phenomenon is of fundamental importance to the design of industrially applicable gas-selective sorbents, which remains under investigated due to the lack of direct structural evidence for such systems. We report a mechanistic study of gas-induced gate-opening process of a microporous metal-organic framework, [Mn(ina)2 ] (ina=isonicotinate) associated with commensurate adsorption, by a combination of several analytical techniques including single crystal X-ray diffraction, in situ powder X-ray diffraction coupled with differential scanning calorimetry (XRD-DSC), and gas adsorption-desorption methods. Our study reveals that the pronounced and reversible gate opening/closing phenomena observed in [Mn(ina)2 ] are coupled with a structural transition that involves rotation of the organic linker molecules as a result of interaction of the framework with adsorbed gas molecules including carbon dioxide and propane. The onset pressure to open the gate correlates with the extent of such interaction. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Metal-free aqueous redox capacitor via proton rocking-chair system in an organic-based couple

    Science.gov (United States)

    Tomai, Takaaki; Mitani, Satoshi; Komatsu, Daiki; Kawaguchi, Yuji; Honma, Itaru

    2014-01-01

    Safe and inexpensive energy storage devices with long cycle lifetimes and high power and energy densities are mandatory for the development of electrical power grids that connect with renewable energy sources. In this study, we demonstrated metal-free aqueous redox capacitors using couples comprising low-molecular-weight organic compounds. In addition to the electric double layer formation, proton insertion/extraction reactions between a couple consisting of inexpensive quinones/hydroquinones contributed to the energy storage. This energy storage mechanism, in which protons are shuttled back and forth between two electrodes upon charge and discharge, can be regarded as a proton rocking-chair system. The fabricated capacitor showed a large capacity (>20 Wh/kg), even in the applied potential range between 0–1 V, and high power capability (>5 A/g). The support of the organic compounds in nanoporous carbon facilitated the efficient use of the organic compounds with a lifetime of thousands of cycles. PMID:24395117

  18. Effect of misalignment of air-coupled probes on Ao Lamb mode propagating in a metal plate.

    Science.gov (United States)

    Ramadas, C; Hood, Avinash; Khan, Irfan; Balasubramaniam, Krishnan

    2014-07-01

    Proper alignment of air-coupled ultrasonic transducers for generation and reception of Lamb waves is vital in order to acquire a high amplitude wave group. Any misalignment with either the transmitter or the receiver or both adversely influences the amplitude of a Lamb mode. This paper reports a systematic attempt to quantify the reduction in the amplitude of the fundamental anti-symmetric Lamb mode (Ao) in a metal plate caused by misalignments in air-coupled probes. Three different types of misalignments - linear, orientation and synchronised orientation were deliberately introduced in the transducers, and experiments were performed on a 6mm thick aluminium plate. Amplitudes of Ao mode measured at various configurations were normalised with that of Ao mode, captured in a reference configuration. Suitable curves fitted over the experimental data points revealed that Gaussian curves represent appropriately the variations in normalised amplitudes of Ao mode. Moreover, analytical expressions were derived to predict the difference in arrival times of Lamb mode(s) due to orientation and synchronised orientation misalignments. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Self-folding miniature elastic electric devices

    International Nuclear Information System (INIS)

    Miyashita, Shuhei; Meeker, Laura; Rus, Daniela; Tolley, Michael T; Wood, Robert J

    2014-01-01

    Printing functional materials represents a considerable impact on the access to manufacturing technology. In this paper we present a methodology and validation of print-and-self-fold miniature electric devices. Polyvinyl chloride laminated sheets based on metalized polyester film show reliable self-folding processes under a heat application, and it configures 3D electric devices. We exemplify this technique by fabricating fundamental electric devices, namely a resistor, capacitor, and inductor. Namely, we show the development of a self-folded stretchable resistor, variable resistor, capacitive strain sensor, and an actuation mechanism consisting of a folded contractible solenoid coil. Because of their pre-defined kinematic design, these devices feature elasticity, making them suitable as sensors and actuators in flexible circuits. Finally, an RLC circuit obtained from the integration of developed devices is demonstrated, in which the coil based actuator is controlled by reading a capacitive strain sensor. (paper)

  20. Fully-Coupled Thermo-Electrical Modeling and Simulation of Transition Metal Oxide Memristors

    Energy Technology Data Exchange (ETDEWEB)

    Mamaluy, Denis [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gao, Xujiao [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Tierney, Brian David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Marinella, Matthew [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mickel, Patrick [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Tierney, Brian D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-11-01

    Transition metal oxide (TMO) memristors have recently attracted special attention from the semiconductor industry and academia. Memristors are one of the strongest candidates to replace flash memory, and possibly DRAM and SRAM in the near future. Moreover, memristors have a high potential to enable beyond-CMOS technology advances in novel architectures for high performance computing (HPC). The utility of memristors has been demonstrated in reprogrammable logic (cross-bar switches), brain-inspired computing and in non-CMOS complementary logic. Indeed, the potential use of memristors as logic devices is especially important considering the inevitable end of CMOS technology scaling that is anticipated by 2025. In order to aid the on-going Sandia memristor fabrication effort with a memristor design tool and establish a clear physical picture of resistance switching in TMO memristors, we have created and validated with experimental data a simulation tool we name the Memristor Charge Transport (MCT) Simulator.

  1. Light transmission through nanostructured metallic films: coupling between surface waves and localized resonances.

    Science.gov (United States)

    Lin, L; Roberts, A

    2011-01-31

    We present an experimental and computational investigation of the optical properties of thin metallic films periodically perforated with nanometric apertures and show that high transmission through such a structure is attributable to the localized surface plasmon (LSP) resonances of the aperture. The periodicity-related optical phenomena, including Wood's anomaly and surface plasmon polariton (SPP) excitation, interfere with LSPs and generate Fano resonances with asymmetric spectral profiles. The transmission maximum of the Fano profile is related to the constructive interference between the LSP field and diffracted light propagating along the surface; the transmission minimum of the Fano profile is caused by the destructive interference between LSPs and SPPs. The study confirms the negative role of SPP in transmission through the structure.

  2. [Determination of heavy metals for RoHS compliance by ICP-OES spectrometry coupled with microwave extraction system].

    Science.gov (United States)

    Hua, Li; Wu, Yi-Ping; An, Bing; Lai, Xiao-Wei

    2008-11-01

    The harm of heavy metals contained in electronic and electrical equipment (EEE) on environment is of high concern by human. Aiming to handle the great challenge of RoHS compliance, the determinations of trace or ultratrace chromium (Cr), cadmium (Cd), mercury (Hg) and lead (Pb) by inductively coupled plasma optical emission spectrometry (ICP-OES) was performed in the present paper, wherein, microwave extraction technology was used to prepare the sample solutions. In addition, the precision, recovery, repeatability and interference issues of this method were also discussed. The results exhibited that using the microwave extraction system to prepare samples is more quick, lossless, contamination-free in comparison with the conventional extraction methods such as dry ashing, wet-oven extraction etc. By analyzing the recoveries of these four heavy metals over different working time and wavelengths, the good recovery range between 85% and 115% showed that there was only tiny loss or contamination during the process of microwave extraction, sample introduction and ICP detection. Repeatability experiments proved that ICP plasma had a good stability during the working time and the matrix effect was small. Interference was a problem troublesome for atomic absorption spectrometry (AAS), however, the techniques of standard additions or inter-element correction (IEC) method can effectively eliminated the interferences of Ni, As, Fe etc. with the Cd determination. By employing the multi-wavelengths and two correction point methods, the issues of background curve sloping shift and spectra overlap were successfully overcome. Besides, for the determinations of trace heavy metal elements, the relative standard deviation (RSD) was less than 3% and the detection limits were less than 1 microg x L(-10 (3sigma, n = 5) for samples, standard solutions, and standard additions, which proved that ICP-OES has a good precision and high reliability. This provided a reliable technique support

  3. Transient current in a quantum dot asymmetrically coupled to metallic leads

    International Nuclear Information System (INIS)

    Goker, A; Friedman, B A; Nordlander, P

    2007-01-01

    The time-dependent non-crossing approximation is used to study the transient current in a single-electron transistor attached asymmetrically to two leads following a sudden change in the energy of the dot level. We show that for asymmetric coupling, sharp features in the density of states of the leads can induce oscillations in the current through the dot. These oscillations persist to much longer timescales than the timescale for charge fluctuations. The amplitude of the oscillations increases as the temperature or source-drain bias across the dot is reduced and saturates for values below the Kondo temperature. We discuss the microscopic origin of these oscillations and comment on the possibility for their experimental detection

  4. The Folded Horn Antenna

    Science.gov (United States)

    Farr, E. G.; Bowen, L. H.; Baum, C. E.; Prather, W. D.

    Antennas for radiating high-power mesoband (medium-bandwidth) electromagnetic signals are critical to the mission of upsetting electronics at a distance. When operated at frequencies of a few hundred megahertz, RF weapons require highly efficient antennas that can fit into a small volume. Most of the existing antennas, such as pyramidal horns, are too large to fit onto certain platforms of interest. To address this challenge, we investigate the folded horn, which has aperture dimensions of 0.5 × 2 wavelengths, and a depth of 1.5-2 wavelengths. This antenna has a nearly focused aperture field, due to a parabolic fold in the H-plane. We report here on the fabrication and testing of the first folded horn, operating at 3 GHz. After a number of iterations, we obtained a realized gain of at least 10 dBi over 3-5 GHz, an aperture efficiency of 80%, and a return loss below -10 dB over 2.8-3.35 GHz. This design could be adapted to high-voltages, and it could work well in a two-antenna array, with two antennas positioned back to back, driven by a differential source.

  5. Numerical simulation of coupled heat and mass transfer in metal hydride-based hydrogen storage reactor

    International Nuclear Information System (INIS)

    Muthukumar, P.; Ramana, S. Venkata

    2009-01-01

    In this paper, a numerical investigation of two-dimensional heat and mass transfer during absorption of hydrogen in a cylindrical metal hydride bed containing MmNi 6.4 Al 0.4 is presented. By considering the variation in cooling fluid temperature along the axial direction (variable wall temperature), the changes in hydrogen concentration, hydride equilibrium pressure, and average hydride bed temperature at different axial locations are presented. The average bed temperature profiles and hydrogen storage capacities at different supply pressures showed good agreement with the experimental data reported in the literature. As the absorption progresses, the change in cooling fluid temperature along the axial direction is found to decrease and becomes unchanged at the end of the absorption process. The effect of variable wall temperature on hydrogen absorption rate for different supply pressures and hydride bed thicknesses are presented. The effect of variable wall temperature on absorption time is found to be significant for the hydride beds of thickness of above 7.5 mm. For a supply pressure of 20 bar, the maximum difference in absorption time between variable wall temperature and constant wall temperature boundary conditions is about 300 s for 17.5 mm bed thickness

  6. Effective DNA binding and cleaving tendencies of malonic acid coupled transition metal complexes

    Science.gov (United States)

    Pravin, Narayanaperumal; Utthra, Ponnukalai Ponya; Kumaravel, Ganesan; Raman, Natarajan

    2016-11-01

    Eight transition metal complexes were designed to achieve maximum biological efficacy. They were characterized by elemental analysis and various other spectroscopic techniques. The monomeric complexes were found to espouse octahedral geometry and non-electrolytic nature. The DNA interaction propensity of the complexes with calf thymus DNA (CT-DNA), studied at physiological pH by spectrophotometric, spectrofluorometric, cyclic voltammetry, and viscometric techniques revealed intercalation as the possible binding mode. Fascinatingly, the complexes were found to exhibit greater binding strength than that of the free ligands. A strong hypochromism and a slight red shift were exhibited by complex 5 among the other complexes. The intrinsic binding constant values of all the complexes compared to cisplatin reveal that they are excellent metallonucleases than that of cisplatin. The complexes were also shown to reveal displacement of the ethidium bromide, a strong intercalator using fluorescence titrations. Gel electrophoresis was used to divulge the competence of the complexes in cleaving the supercoiled pBR322 plasmid DNA. From the results, it is concluded that the complexes, especially 5, are excellent chemical nucleases in the presence of H2O2. Furthermore, the in vitro antimicrobial screening of the complexes exposes that these complexes are excellent antimicrobial agents. Overall the effect of coligands is evident from the results of all the investigations.

  7. Quantitative images of metals in plant tissues measured by laser ablation inductively coupled plasma mass spectrometry

    International Nuclear Information System (INIS)

    Becker, J.S.; Dietrich, R.C.; Matusch, A.; Pozebon, D.; Dressler, V.L.

    2008-01-01

    Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was used for quantitative imaging of toxic and essential elements in thin sections (thickness of 30 or 40 μm) of tobacco plant tissues. Two-dimensional images of Mg, Fe, Mn, Zn, Cu, Cd, Rh, Pt and Pb in leaves, shoots and roots of tobacco were produced. Sections of the plant tissues (fixed onto glass slides) were scanned by a focused beam of a Nd:YAG laser in a laser ablation chamber. The ablated material was transported with argon as carrier gas to the ICP ion source at a quadrupole ICP-MS instrument. Ion intensities of the investigated elements were measured together with 13 C + , 33 S + and 34 S + within the entire plant tissue section. Matrix matching standards (prepared using powder of dried tobacco leaves) were used to constitute calibration curves, whereas the regression coefficient of the attained calibration curves was typically 0.99. The variability of LA-ICP-MS process, sample heterogeneity and water content in the sample were corrected by using 13 C + as internal standard. Quantitative imaging of the selected elements revealed their inhomogeneous distribution in leaves, shoots and roots

  8. Dynamic considerations for composite metal-rubber laminate acoustic power coupling bellows with application to thermoacoustic refrigeration

    Science.gov (United States)

    Smith, Robert William

    Many electrically driven thermoacoustic refrigerators have employed corrugated metal bellows to couple work from an electro-mechanical transducer to the working fluid typically. An alternative bellows structure to mediate this power transfer is proposed: a laminated hollow cylinder comprised of alternating layers of rubber and metal 'hoop-stack'. Fatigue and visoelastic power dissipation in the rubber are critical considerations; strain energy density plays a role in both. Optimal aspect ratios for a rectangle corss-section in the rubber, for given values of bellows axial strain and oscillatory pressure loads are discussed. Comparisons of tearing energies estimated from known load cases and those obtained by finite element analysis for candidate dimensions are presented. The metal layers of bellows are subject to an out-of-plane buckling instability for the case of external pressure loading; failure of this type was experimentally observed. The proposed structure also exhibits column instability when subject to internal pressure, as do metal bellows. For hoop-stack bellows, shear deflection cannot be ignored and this leads to column instability for both internal and external pressures, the latter being analogous to the case of tension buckling of a beam. During prototype bellows testing, transverse modes of vibration are believed to have been excited parametrically as a consequence of the oscillatory pressures. Some operating frequencies of interest in this study lie above the cut-on frequency at which Timoshenko beam theory (TBT) predicts multiple phase speeds; it is shown that TBT fails to accurately predict both mode shapes and resonance frequencies in this regime. TBT is also shown to predict multiple phase speeds in the presence of axial tension, or external pressures, at magnitudes of interest in this study, over the entire frequency spectrum. For modes below cut-on absent a pressure differential (or equivalently, axial load) TBT predicts decreasing resonance

  9. Novel bioimaging techniques of metals by laser ablation inductively coupled plasma mass spectrometry for diagnosis of fibrotic and cirrhotic liver disorders.

    Directory of Open Access Journals (Sweden)

    Pornwilard M-M

    Full Text Available BACKGROUND AND AIMS: Hereditary disorders associated with metal overload or unwanted toxic accumulation of heavy metals can lead to morbidity and mortality. Patients with hereditary hemochromatosis or Wilson disease for example may develop severe hepatic pathology including fibrosis, cirrhosis or hepatocellular carcinoma. While relevant disease genes are identified and genetic testing is applicable, liver biopsy in combination with metal detecting techniques such as energy-dispersive X-ray spectroscopy (EDX is still applied for accurate diagnosis of metals. Vice versa, several metals are needed in trace amounts for carrying out vital functions and their deficiency due to rapid growth, pregnancy, excessive blood loss, and insufficient nutritional or digestive uptake results in organic and systemic shortcomings. Established in situ techniques, such as EDX-ray spectroscopy, are not sensitive enough to analyze trace metal distribution and the quantification of metal images is difficult. METHODS: In this study, we developed a quantitative biometal imaging technique of human liver tissue by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS in order to compare the distribution of selected metals in cryo-sections of healthy and fibrotic/cirrhotic livers. RESULTS: Most of the metals are homogeneous distributed within the normal tissue, while they are redirected within fibrotic livers resulting in significant metal deposits. Moreover, total iron and copper concentrations in diseased liver were found about 3-5 times higher than in normal liver samples. CONCLUSIONS: Biometal imaging via LA-ICP-MS is a sensitive innovative diagnostic tool that will impact clinical practice in identification and evaluation of hepatic metal disorders and to detect subtle metal variations during ongoing hepatic fibrogenesis.

  10. Coupling scales for modelling heavy metal vaporization from municipal solid waste incineration in a fluid bed by CFD

    Energy Technology Data Exchange (ETDEWEB)

    Soria, José, E-mail: jose.soria@probien.gob.ar [Institute for Research and Development in Process Engineering, Biotechnology and Alternative Energies (PROBIEN, CONICET – UNCo), 1400 Buenos Aires St., 8300 Neuquén (Argentina); Gauthier, Daniel; Flamant, Gilles [Processes, Materials and Solar Energy Laboratory (PROMES-CNRS, UPR 8521), 7 Four Solaire Street, Odeillo, 66120 Font-Romeu (France); Rodriguez, Rosa [Chemical Engineering Institute, National University of San Juan, 1109 Libertador (O) Avenue, 5400 San Juan (Argentina); Mazza, Germán [Institute for Research and Development in Process Engineering, Biotechnology and Alternative Energies (PROBIEN, CONICET – UNCo), 1400 Buenos Aires St., 8300 Neuquén (Argentina)

    2015-09-15

    Highlights: • A CFD two-scale model is formulated to simulate heavy metal vaporization from waste incineration in fluidized beds. • MSW particle is modelled with the macroscopic particle model. • Influence of bed dynamics on HM vaporization is included. • CFD predicted results agree well with experimental data reported in literature. • This approach may be helpful for fluidized bed reactor modelling purposes. - Abstract: Municipal Solid Waste Incineration (MSWI) in fluidized bed is a very interesting technology mainly due to high combustion efficiency, great flexibility for treating several types of waste fuels and reduction in pollutants emitted with the flue gas. However, there is a great concern with respect to the fate of heavy metals (HM) contained in MSW and their environmental impact. In this study, a coupled two-scale CFD model was developed for MSWI in a bubbling fluidized bed. It presents an original scheme that combines a single particle model and a global fluidized bed model in order to represent the HM vaporization during MSW combustion. Two of the most representative HM (Cd and Pb) with bed temperatures ranging between 923 and 1073 K have been considered. This new approach uses ANSYS FLUENT 14.0 as the modelling platform for the simulations along with a complete set of self-developed user-defined functions (UDFs). The simulation results are compared to the experimental data obtained previously by the research group in a lab-scale fluid bed incinerator. The comparison indicates that the proposed CFD model predicts well the evolution of the HM release for the bed temperatures analyzed. It shows that both bed temperature and bed dynamics have influence on the HM vaporization rate. It can be concluded that CFD is a rigorous tool that provides valuable information about HM vaporization and that the original two-scale simulation scheme adopted allows to better represent the actual particle behavior in a fluid bed incinerator.

  11. Towards a systematic classification of protein folds

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker; Bohr, Henrik

    1997-01-01

    structures are given a unique name, which simultaneously represent a linear string of physical coupling constants describing hinge spin interactions. We have defined a metric and a precise distance measure between the fold classes. An automated procedure is constructed in which any protein structure...... magic number of secondary structures. Thermodynamic arguments for the increased abundance and a phase diagram for the folding scenario are given. This includes an intermediate high symmetry phase, the parent structures, between the molten globule and the native states. We have made an exhaustive...

  12. Coupling catalytic hydrolysis and oxidation of HCN over HZSM-5 modified by metal (Fe,Cu) oxides

    Science.gov (United States)

    Hu, Yanan; Liu, Jiangping; Cheng, Jinhuan; Wang, Langlang; Tao, Lei; Wang, Qi; Wang, Xueqian; Ning, Ping

    2018-01-01

    In this work, a series of metal oxides (Fe,Cu) modified HZSM-5 catalysts were synthesized by incipient-wetness impregnation method and then characterized by XRD, N2 adsorption-desorption, H2-TPR, NH3-TPD, UV-vis, FT-IR and XPS measurements. The catalytic hydrolysis and oxidation behaviors toward HCN were investigated. The results indicated that the Fe-Cu/HZSM-5 catalysts exhibited more excellent performence on coupling catalytic hydrolysis and oxidation of HCN than HZSM-5, Fe/HZSM-5, Cu/HZSM-5, and both nearly 100% HCN conversion and 80% N2 selectivity were obtained at about 250 °C. The improved catalytic performance could be ascribed to the creation of highly dispersed iron and copper composites on the surface of the HZSM-5 support, the excellent redox and regulated acid properties of the active ingredients. Moreover, the highly N2 selectivity could be attributed to the good interaction between the Fe and Cu nanocomposites which was facilitated to the NH3-SCR (selective catalytic reduction of NO by NH3) reaction.

  13. Coupled Electrokinetics-Adsorption Technique for Simultaneous Removal of Heavy Metals and Organics from Saline-Sodic Soil

    Science.gov (United States)

    Lukman, Salihu; Essa, Mohammed Hussain; Mu'azu, Nuhu Dalhat; Bukhari, Alaadin

    2013-01-01

    In situ remediation technologies for contaminated soils are faced with significant technical challenges when the contaminated soil has low permeability. Popular traditional technologies are rendered ineffective due to the difficulty encountered in accessing the contaminants as well as when employed in settings where the soil contains mixed contaminants such as petroleum hydrocarbons, heavy metals, and polar organics. In this study, an integrated in situ remediation technique that couples electrokinetics with adsorption, using locally produced granular activated carbon from date palm pits in the treatment zones that are installed directly to bracket the contaminated soils at bench-scale, is investigated. Natural saline-sodic soil, spiked with contaminant mixture (kerosene, phenol, Cr, Cd, Cu, Zn, Pb, and Hg), was used in this study to investigate the efficiency of contaminant removal. For the 21-day period of continuous electrokinetics-adsorption experimental run, efficiency for the removal of Zn, Pb, Cu, Cd, Cr, Hg, phenol, and kerosene was found to reach 26.8, 55.8, 41.0, 34.4, 75.9, 92.49, 100.0, and 49.8%, respectively. The results obtained suggest that integrating adsorption into electrokinetic technology is a promising solution for removal of contaminant mixture from saline-sodic soils. PMID:24235885

  14. Liquid-phase extraction coupled with metal-organic frameworks-based dispersive solid phase extraction of herbicides in peanuts.

    Science.gov (United States)

    Li, Na; Wang, Zhibing; Zhang, Liyuan; Nian, Li; Lei, Lei; Yang, Xiao; Zhang, Hanqi; Yu, Aimin

    2014-10-01

    Liquid-phase extraction coupled with metal-organic frameworks-based dispersive solid phase extraction was developed and applied to the extraction of pesticides in high fatty matrices. The herbicides were ultrasonically extracted from peanut using ethyl acetate as extraction solvent. The separation of the analytes from a large amount of co-extractive fat was achieved by dispersive solid-phase extraction using MIL-101(Cr) as sorbent. In this step, the analytes were adsorbed on MIL-101(Cr) and the fat remained in bulk. The herbicides were separated and determined by high-performance liquid chromatography. The experimental parameters, including type and volume of extraction solvent, ultrasonication time, volume of hexane and eluting solvent, amount of MIL-101(Cr) and dispersive solid phase extraction time, were optimized. The limits of detection for herbicides range from 0.98 to 1.9 μg/kg. The recoveries of the herbicides are in the range of 89.5-102.7% and relative standard deviations are equal or lower than 7.0%. The proposed method is simple, effective and suitable for treatment of the samples containing high content of fat. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. The effect of metal ions released from different dental implant-abutment couples on osteoblast function and secretion of bone resorbing mediators.

    Science.gov (United States)

    Alrabeah, Ghada O; Brett, Peter; Knowles, Jonathan C; Petridis, Haralampos

    2017-11-01

    The etiology of the reduced marginal bone loss observed around platform-switched implant-abutment connections is not clear but could be related to the release of variable amounts of corrosion products. The present study evaluated the effect of different concentrations of metal ions released from different implant abutment couples on osteoblastic cell viability, apoptosis and expression of genes related to bone resorption. Osteoblastic cells were exposed to five conditions of culture media prepared containing metal ions (titanium, aluminum, vanadium, cobalt, chromium and molybdenum) in different concentrations representing the amounts released from platform-matched and platform-switched implant-abutment couples as a result of an earlier accelerated corrosion experiment. Cell viability was evaluated over 21days using the Alamar Blue assay. Induction of apoptosis was measured after 24h of exposure using flow cytometry. Expression of interleukin-6, interleukin-8, cyclooxygenase-2, caspase-8, osteoprotegerin and receptor activator of nuclear factor kappa-B ligand (RANKL) by osteoblastic cells were analysed after exposure for 1, 3 and 21days using real-time quantitative polymerase chain reaction assay RESULTS: Metal ions in concentrations representing the platform-matched groups led to a reduction in cell viability (PMetal ions up-regulated the expression of interleukin-6, interleukin-8, cyclooxygenase-2 and RANKL in a dose dependent manner after 1day of exposure (Pmetal ions. The change in cytokine levels expressed was directly proportional to the metal ion concentration. The observed biological responses to decreased amounts of metal ions released from platform-switched implant-abutment couples compared to platform-matched couples may partly explain the positive radiographic findings in respect to crestal bone level when utilising the "platform-switching" concept, which highlights the possible role of corrosion products in the mediation of crestal bone loss around

  16. The Ventricular-Fold Dynamics in Human Phonation

    OpenAIRE

    Bailly , Lucie; Henrich Bernardoni , Nathalie; Müller , Frank; Rohlfs , Anna-Katharina; Hess , Markus

    2014-01-01

    International audience; Purpose: In this study, the authors aimed (a) to provide a classification of the ventricular-fold dynamics during voicing, (b) to study the aerodynamic impact of these motions on vocal-fold vibrations, and (c) to assess whether ventricularfold oscillations could be sustained by aerodynamic coupling with the vocal folds. Method: A 72-sample database of vocal gestures accompanying different acoustical events comprised highspeed cinematographic, audio, and electroglottogr...

  17. Determination of Heavy Metals through Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES in Iranian Cheese and Their Potential Health Risks to the Adult Consumers

    Directory of Open Access Journals (Sweden)

    Elham Baseri

    2017-10-01

    Full Text Available In Iran, cheese is one of the dairy products that widely consumed as a main diet for breakfast. Moreover, trace metals in dairy products have recently gained considerable attention. Iranian cheese samples were collected from Tehran, Iran (February in May 2013. Trace metals including Pb, Cd, Ni, Fe, Sn, Zn, Cr, and Cu were analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES after dry ashing. All the tested metals were detected in the cheese samples. The mean concentration of metals in cheese showed the following decreasing order Zn > Fe > Cu > Ni > Sn > Cr > Pb > Cd, with values of 12.98, 7.95, 1.96, 0.83, 0.46, 0.37, 0.34, and 0.01 mg/kg, respectively. There were no significant differences between types of cheese samples in terms of content of trace metals (p>0.05. All the samples had Pb contents of greater than Codex limit (0.02 mg/kg. According to the measured values of the metals in this study, the intake of all the studied elements through the common consumption of cheese in Iran was below the dangerous level according to permissible intake value for each metal. Also, levels of correlations between the element pairs were analyzed.

  18. The Complexity of Folding Self-Folding Origami

    Directory of Open Access Journals (Sweden)

    Menachem Stern

    2017-12-01

    Full Text Available Why is it difficult to refold a previously folded sheet of paper? We show that even crease patterns with only one designed folding motion inevitably contain an exponential number of “distractor” folding branches accessible from a bifurcation at the flat state. Consequently, refolding a sheet requires finding the ground state in a glassy energy landscape with an exponential number of other attractors of higher energy, much like in models of protein folding (Levinthal’s paradox and other NP-hard satisfiability (SAT problems. As in these problems, we find that refolding a sheet requires actuation at multiple carefully chosen creases. We show that seeding successful folding in this way can be understood in terms of subpatterns that fold when cut out (“folding islands”. Besides providing guidelines for the placement of active hinges in origami applications, our results point to fundamental limits on the programmability of energy landscapes in sheets.

  19. The Complexity of Folding Self-Folding Origami

    Science.gov (United States)

    Stern, Menachem; Pinson, Matthew B.; Murugan, Arvind

    2017-10-01

    Why is it difficult to refold a previously folded sheet of paper? We show that even crease patterns with only one designed folding motion inevitably contain an exponential number of "distractor" folding branches accessible from a bifurcation at the flat state. Consequently, refolding a sheet requires finding the ground state in a glassy energy landscape with an exponential number of other attractors of higher energy, much like in models of protein folding (Levinthal's paradox) and other NP-hard satisfiability (SAT) problems. As in these problems, we find that refolding a sheet requires actuation at multiple carefully chosen creases. We show that seeding successful folding in this way can be understood in terms of subpatterns that fold when cut out ("folding islands"). Besides providing guidelines for the placement of active hinges in origami applications, our results point to fundamental limits on the programmability of energy landscapes in sheets.

  20. Coupling scales for modelling heavy metal vaporization from municipal solid waste incineration in a fluid bed by CFD.

    Science.gov (United States)

    Soria, José; Gauthier, Daniel; Flamant, Gilles; Rodriguez, Rosa; Mazza, Germán

    2015-09-01

    Municipal Solid Waste Incineration (MSWI) in fluidized bed is a very interesting technology mainly due to high combustion efficiency, great flexibility for treating several types of waste fuels and reduction in pollutants emitted with the flue gas. However, there is a great concern with respect to the fate of heavy metals (HM) contained in MSW and their environmental impact. In this study, a coupled two-scale CFD model was developed for MSWI in a bubbling fluidized bed. It presents an original scheme that combines a single particle model and a global fluidized bed model in order to represent the HM vaporization during MSW combustion. Two of the most representative HM (Cd and Pb) with bed temperatures ranging between 923 and 1073K have been considered. This new approach uses ANSYS FLUENT 14.0 as the modelling platform for the simulations along with a complete set of self-developed user-defined functions (UDFs). The simulation results are compared to the experimental data obtained previously by the research group in a lab-scale fluid bed incinerator. The comparison indicates that the proposed CFD model predicts well the evolution of the HM release for the bed temperatures analyzed. It shows that both bed temperature and bed dynamics have influence on the HM vaporization rate. It can be concluded that CFD is a rigorous tool that provides valuable information about HM vaporization and that the original two-scale simulation scheme adopted allows to better represent the actual particle behavior in a fluid bed incinerator. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Detection of charge dynamics of a tetraphenylporphyrin particle using GaAs-based nanowire enhanced by particle-metal tip capacitive coupling

    Science.gov (United States)

    Okamoto, Shoma; Sato, Masaki; Sasaki, Kentaro; Kasai, Seiya

    2017-06-01

    We investigate a detection technique of charge dynamics of a molecular particle using a GaAs-based nanowire where the charge sensitivity is locally enhanced by particle-metal tip capacitive coupling. By equivalent circuit analysis, it was clarified that the nanowire channel potential becomes sensitive to the molecular particle on the nanowire when the particle is capacitively coupled with a metal tip. The concept was demonstrated using a GaAs-based nanowire with tetraphenylporphyrin (TPP) particles on its surface and a measurement system integrating an atomic force microscope (AFM) and a dynamic current measurement monitor/spectrum analyzer. When the metal tip was in contact with a TPP particle on the nanowire under an appropriate tip bias condition, random telegraph signal (RTS) noise was imposed on the nanowire current, suggesting the increase in sensitivity to the charge state of the particle by the metal tip contact. We discussed the origin of the RTS noise through analysis of the time constant of RTS noise, RTS amplitude, and noise spectrum.

  2. Evolutionary optimization of protein folding.

    Directory of Open Access Journals (Sweden)

    Cédric Debès

    Full Text Available Nature has shaped the make up of proteins since their appearance, [Formula: see text]3.8 billion years ago. However, the fundamental drivers of structural change responsible for the extraordinary diversity of proteins have yet to be elucidated. Here we explore if protein evolution affects folding speed. We estimated folding times for the present-day catalog of protein domains directly from their size-modified contact order. These values were mapped onto an evolutionary timeline of domain appearance derived from a phylogenomic analysis of protein domains in 989 fully-sequenced genomes. Our results show a clear overall increase of folding speed during evolution, with known ultra-fast downhill folders appearing rather late in the timeline. Remarkably, folding optimization depends on secondary structure. While alpha-folds showed a tendency to fold faster throughout evolution, beta-folds exhibited a trend of folding time increase during the last [Formula: see text]1.5 billion years that began during the "big bang" of domain combinations. As a consequence, these domain structures are on average slow folders today. Our results suggest that fast and efficient folding of domains shaped the universe of protein structure. This finding supports the hypothesis that optimization of the kinetic and thermodynamic accessibility of the native fold reduces protein aggregation propensities that hamper cellular functions.

  3. Coupled transfers; Transferts couples

    Energy Technology Data Exchange (ETDEWEB)

    Nicolas, X.; Lauriat, G.; Jimenez-Rondan, J. [Universite de Marne-la-Vallee, Lab. d' Etudes des Transferts d' Energie et de Matiere (LETEM), 77 (France); Bouali, H.; Mezrhab, A. [Faculte des Sciences, Dept. de Physique, Lab. de Mecanique et Energetique, Oujda (Morocco); Abid, C. [Ecole Polytechnique Universitaire de Marseille, IUSTI UMR 6595, 13 Marseille (France); Stoian, M.; Rebay, M.; Lachi, M.; Padet, J. [Faculte des Sciences, Lab. de Thermomecanique, UTAP, 51 - Reims (France); Mladin, E.C. [Universitaire Polytechnique Bucarest, Faculte de Genie Mecanique, Bucarest (Romania); Mezrhab, A. [Faculte des Sciences, Lab. de Mecanique et Energetique, Dept. de Physique, Oujda (Morocco); Abid, C.; Papini, F. [Ecole Polytechnique, IUSTI, 13 - Marseille (France); Lorrette, C.; Goyheneche, J.M.; Boechat, C.; Pailler, R. [Laboratoire des Composites ThermoStructuraux, UMR 5801, 33 - Pessac (France); Ben Salah, M.; Askri, F.; Jemni, A.; Ben Nasrallah, S. [Ecole Nationale d' Ingenieurs de Monastir, Lab. d' Etudes des Systemes Thermiques et Energetiques (Tunisia); Grine, A.; Desmons, J.Y.; Harmand, S. [Laboratoire de Mecanique et d' Energetique, 59 - Valenciennes (France); Radenac, E.; Gressier, J.; Millan, P. [ONERA, 31 - Toulouse (France); Giovannini, A. [Institut de Mecanique des Fluides de Toulouse, 31 (France)

    2005-07-01

    This session about coupled transfers gathers 30 articles dealing with: numerical study of coupled heat transfers inside an alveolar wall; natural convection/radiant heat transfer coupling inside a plugged and ventilated chimney; finite-volume modeling of the convection-conduction coupling in non-stationary regime; numerical study of the natural convection/radiant heat transfer coupling inside a partitioned cavity; modeling of the thermal conductivity of textile reinforced composites: finite element homogenization on a full periodical pattern; application of the control volume method based on non-structured finite elements to the problems of axisymmetrical radiant heat transfers in any geometries; modeling of convective transfers in transient regime on a flat plate; a conservative method for the non-stationary coupling of aero-thermal engineering codes; measurement of coupled heat transfers (forced convection/radiant transfer) inside an horizontal duct; numerical simulation of the combustion of a water-oil emulsion droplet; numerical simulation study of heat and mass transfers inside a reactor for nano-powders synthesis; reduction of a combustion and heat transfer model of a direct injection diesel engine; modeling of heat transfers inside a knocking operated spark ignition engine; heat loss inside an internal combustion engine, thermodynamical and flamelet model, composition effects of CH{sub 4}H{sub 2} mixtures; experimental study and modeling of the evolution of a flame on a solid fuel; heat transfer for laminar subsonic jet of oxygen plasma impacting an obstacle; hydrogen transport through a A-Si:H layer submitted to an hydrogen plasma: temperature effects; thermal modeling of the CO{sub 2} laser welding of a magnesium alloy; radiant heat transfer inside a 3-D environment: application of the finite volume method in association with the CK model; optimization of the infrared baking of two types of powder paints; optimization of the emission power of an infrared

  4. Valley and band structure engineering of folded MoS(2) bilayers.

    Science.gov (United States)

    Jiang, Tao; Liu, Hengrui; Huang, Di; Zhang, Shuai; Li, Yingguo; Gong, Xingao; Shen, Yuen-Ron; Liu, Wei-Tao; Wu, Shiwei

    2014-10-01

    Artificial structures made of stacked two-dimensional crystals have recently been the focus of intense research activity. As in twisted or stacked graphene layers, these structures can show unusual behaviours and new phenomena. Among the various layered compounds that can be exfoliated, transition-metal dichalcogenides exhibit interesting properties governed by their structural symmetry and interlayer coupling, which are highly susceptible to stacking. Here, we obtain-by folding exfoliated MoS2 monolayers-MoS2 bilayers with different stacking orders, as monitored by second harmonic generation and photoluminescence. Appropriate folding can break the inversion symmetry and suppress interlayer hopping, evoking strong valley and spin polarizations that are not achieved in natural MoS2 bilayers of Bernal stacking. It can also enlarge the indirect bandgap by more than 100 meV through a decrease in the interlayer coupling. Our work provides an effective and versatile means to engineer transition-metal dichalcogenide materials with desirable electronic and optical properties.

  5. Equi-Gaussian curvature folding

    Indian Academy of Sciences (India)

    have the same equi-Gaussian curvature 1/a2, where a is the radius of the sphere. Now let f : S2 → Pn be a cellular folding. Then we have the following possibilities: Firstly, there are no cellular foldings f : S2 → Pn, for any n > 3 [2]. Secondly, any cellular folding f : S2 → P3 for which Gf forms a regular graph is equivalent to ...

  6. Self-folding graphene-polymer bilayers

    International Nuclear Information System (INIS)

    Deng, Tao; Yoon, ChangKyu; Jin, Qianru; Li, Mingen; Liu, Zewen; Gracias, David H.

    2015-01-01

    In order to incorporate the extraordinary intrinsic thermal, electrical, mechanical, and optical properties of graphene with three dimensional (3D) flexible substrates, we introduce a solvent-driven self-folding approach using graphene-polymer bilayers. A polymer (SU-8) film was spin coated atop chemically vapor deposited graphene films on wafer substrates and graphene-polymer bilayers were patterned with or without metal electrodes using photolithography, thin film deposition, and etching. After patterning, the bilayers were released from the substrates and they self-folded to form fully integrated, curved, and folded structures. In contrast to planar graphene sensors on rigid substrates, we assembled curved and folded sensors that are flexible and they feature smaller form factors due to their 3D geometry and large surface areas due to their multiple rolled architectures. We believe that this approach could be used to assemble a range of high performance 3D electronic and optical devices of relevance to sensing, diagnostics, wearables, and energy harvesting

  7. Continuous metal scavenging and coupling to one-pot copper-catalyzed azide-alkyne cycloaddition click reaction in flow

    NARCIS (Netherlands)

    Vural - Gursel, Dr. Iris; Aldiansyah, Ferry; Wang, Qi; Noël, Timothy; Hessel, Volker

    2015-01-01

    Increasing usage of catalytic chemistry calls for efficient removal of metal traces. This paper describes the development and optimization of a scavenger-based extraction in flow to remove metal catalysts. It enables liquid-liquid extraction with slug flow and phase separation with a porous

  8. Atomistic modeling of metal surfaces under electric fields: direct coupling of electric fields to a molecular dynamics algorithm

    CERN Document Server

    Djurabekova, Flyura; Pohjonen, Aarne; Nordlund, Kai

    2011-01-01

    The effect of electric fields on metal surfaces is fairly well studied, resulting in numerous analytical models developed to understand the mechanisms of ionization of surface atoms observed at very high electric fields, as well as the general behavior of a metal surface in this condition. However, the derivation of analytical models does not include explicitly the structural properties of metals, missing the link between the instantaneous effects owing to the applied field and the consequent response observed in the metal surface as a result of an extended application of an electric field. In the present work, we have developed a concurrent electrodynamic–molecular dynamic model for the dynamical simulation of an electric-field effect and subsequent modification of a metal surface in the framework of an atomistic molecular dynamics (MD) approach. The partial charge induced on the surface atoms by the electric field is assessed by applying the classical Gauss law. The electric forces acting on the partially...

  9. A parity-breaking electronic nematic phase transition in the spin-orbit coupled correlated metal Cd2Re2O7

    Science.gov (United States)

    Harter, J. W.; Zhao, Z. Y.; Yan, J.-Q.; Mandrus, D. G.; Hsieh, D.

    Strong interactions between electrons are known to drive metallic systems toward a variety of well-known symmetry-broken phases, including superconducting, electronic liquid crystalline, and charge- and spin-density wave ordered states. In contrast, the electronic instabilities of correlated metals with strong spin-orbit coupling have only recently begun to be explored. We uncover a novel multipolar nematic phase of matter in the metallic pyrochlore Cd2Re2O7 using spatially-resolved second-harmonic optical anisotropy measurements. Like previously discovered electronic liquid crystalline phases, this multipolar nematic phase spontaneously breaks rotational symmetry while preserving translational invariance. However, it has the distinguishing property of being odd under spatial inversion, which is allowed only in the presence of spin-orbit coupling. By examining the critical behavior of the multipolar nematic order parameter, we show that it drives the thermal phase transition near 200 K in Cd2Re2O7 and induces a parity-breaking lattice distortion as a secondary order parameter.

  10. Study of the leaching of heavy metals from waste water sludge and incinerator's ash, using coupled thermostated columns and DTPA as complex agent

    International Nuclear Information System (INIS)

    Vite T, J.; Vite T, M.; Guerrero D, J.; Carreno de Leon, M.C.

    2000-01-01

    We studied the metallic composition from waste water sludge and incinerators ashes of an incinerator located in Toluca, Mexico, the qualitative studies were made using the Activation Analysis technique, and fluorescence X-ray techniques. The quantitative analysis of heavy metals in the wastes were made using Inductively coupled plasma atomic emission spectrometry (Icp-Aes). For leaching the samples, we used four coupled thermostated columns, each one had a p H of 2,5, 7 and 10. The flux of the air was of 1600 cc/min. The temperature was maintain constant in 60 Centigrade using a thermostated system. For this study we used 100 g of wastes mixed with mineral acid or sodium hydroxide to reach p H 2,5,7 and 10. We added a reducing and tensoactive agents and finally DTPA as complex agent. With this method, we obtain a better leaching efficiency using a complex agent. However the high DTPA cost, make this process expansive that is why we recommend to work with another classes of complex agents, that be cheaper to leach metals of different chemistry matrix. (Author)

  11. Feasibility of asymmetric flow field-flow fractionation coupled to ICP-MS for the characterization of wear metal particles and metalloproteins in biofluids from hip replacement patients.

    Science.gov (United States)

    Loeschner, Katrin; Harrington, Chris F; Kearney, Jacque-Lucca; Langton, David J; Larsen, Erik H

    2015-06-01

    Hip replacements are used to improve the quality of life of people with orthopaedic conditions, but the use of metal-on-metal (MoM) arthroplasty has led to poor outcomes for some patients. These problems are related to the generation of micro- to nanosized metal wear particles containing Cr, Co or other elements, but the current analytical methods used to investigate the processes involved do not provide sufficient information to understand the size or composition of the wear particles generated in vivo. In this qualitative feasibility study, asymmetric flow field-flow fractionation (AF(4)) coupled with inductively coupled plasma mass spectrometry (ICP-MS) was used to investigate metal protein binding and the size and composition of wear metal particles present in serum and hip aspirates from MoM hip replacement patients. A well-established HPLC anion exchange chromatography (AEC) separation system coupled to ICP-MS was used to confirm the metal-protein associations in the serum samples. Off-line single particle ICP-MS (spICP-MS) analysis was used to confirm the approximate size distribution indicated by AF(4) of the wear particles in hip aspirates. In the serum samples, AF(4) -ICP-MS suggested that Cr was associated with transferrin (Tf) and Co with albumin (Alb) and an unidentified species; AEC-ICP-MS confirmed these associations and also indicated an association of Cr with Alb. In the hip aspirate sample, AF(4)-ICP-MS suggested that Cr was associated with Alb and Tf and that Co was associated with Alb and two unidentified compounds; AEC analysis confirmed the Cr results and the association of Co with Alb and a second compound. Enzymatic digestion of the hip aspirate sample, followed by separation using AF(4) with detection by UV absorption (280 nm), multi-angle light scattering and ICP-MS, suggested that the sizes of the Cr-, Co- and Mo-containing wear particles in a hip aspirate sample were in the range 40-150 nm. Off-line spICP-MS was used to confirm these

  12. Teaching computers to fold proteins

    DEFF Research Database (Denmark)

    Winther, Ole; Krogh, Anders Stærmose

    2004-01-01

    A new general algorithm for optimization of potential functions for protein folding is introduced. It is based upon gradient optimization of the thermodynamic stability of native folds of a training set of proteins with known structure. The iterative update rule contains two thermodynamic averages...

  13. On-line dynamic extraction system hyphenated to inductively coupled plasma optical emission spectrometry for automatic determination of oral bioaccessible trace metal fractions in airborne particulate matter.

    Science.gov (United States)

    Mohr, Victoria; Miró, Manuel; Limbeck, Andreas

    2017-04-01

    For a realistic evaluation of the potential hazard emanating from airborne particulate matter (APM), the determination of the total inhaled metal amounts associated with APM is insufficient in risk assessment. Additional information about metal fractions that can be mobilized by the human body is necessary, because only those soluble (also called bioaccessible) fractions can be absorbed by the human body, and thus potentially cause adverse health effects. In the present study, a dynamic flow-through approach as a front end to inductively coupled plasma optical emission spectrometry (ICP-OES) exploiting advanced flow analysis is employed for on-line handling of multiple APM samples and determination of bioaccessible trace metals under worst case extraction scenarios. The method is based on on-line continuous extraction of filter samples with synthetic gastric fluid followed by on-line ICP-OES measurement of the dissolved fraction of trace metals. The assembly permits an automated successive measurement of three sample replicates in less than 19 min. The on-line extraction procedure offers increased sample throughput and reduced risk of sample contamination and overcomes metal re-adsorption processes compared to the traditional batch-wise counterparts. Furthermore, it provides deeper information on the kinetics of the leaching process. The developed procedure was applied to the determination of bioaccessible metal fractions (Al, Ba, Cu, Fe and Mn as model analytes) in PM10 samples from Palma de Mallorca (Spain) and Vienna (Austria). Graphical Abstract On-line gastric bioaccessibility of elements in airborne particulate matter.

  14. Improved immobilization of 8-hydroxyquinoline on polyacrylonitrile fiber and application of the material to the determination of trace metals in seawater by inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    Wen, Bei; Shan, Xiao-Quan

    2002-11-01

    A modified synthetic method has been developed for immobilization of 8-hydroxyquinoline on polyacrylonitrile fiber. The synthetic conditions, e.g. reagent concentration, reaction temperature and time, were optimized. The features of the newly-modified fiber are higher exchange capacity compared with most other materials containing immobilized 8-hydroxyquinoline, better mechanic characteristics, high stability at both high and low pH, and ease of synthesis. This modified fiber can concentrate and separate trace metals from matrices with higher concentrations of alkali and alkaline earth elements. To validate the characteristics of the modified fiber, trace metals Ag, Be, Cd, Co, Cu, Mn, Ni, Pb, and Zn in the certified reference materials river water (SLRS-4) and seawater (CASS-4, NASS-5, SLEW-3) were preconcentrated before determination by inductively coupled plasma mass spectrometry. Good agreement was obtained between the data obtained by this method and the certified values.

  15. Standard test method for the determination of impurities in plutonium metal: acid digestion and inductively coupled plasma-mass spectroscopy (ICP-MS) analysis

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2006-01-01

    1.1 This Test Method covers the determination of 58 trace elements in plutonium (Pu) metal. The Pu sample is dissolved in acid, and the concentration of the trace impurities are determined by Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS). 1.2 This Test Method is specific for the determination of trace impurities in Pu metal. It may be applied to other types of Pu materials, such as Pu oxides, if the samples are dissolved and oxidized to the Pu(IV) state. However, it is the responsibility of the user to evaluate the performance of other matrices. 1.3 This standard does not purport to address all of the safety concerns associated with its use. It is the responsibility of the user of this method to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use of this standard.

  16. Coupled atmosphere-soil-vegetation modelling for the assessment of the impact of atmospheric releases of heavy metals and of persistent organic pollutants at the European scale

    International Nuclear Information System (INIS)

    Queguiner, Solen

    2008-01-01

    The objective of this research thesis is to couple a model of atmospheric dispersion with a multi-environment model in order to perform impact studies related to atmospheric pollution by heavy metals and POPs (persistent organic pollutants). The author first presents the studied pollutants, their physical and chemical properties, and their effects on health. Then, he addresses the atmospheric modelling with a presentation of the used atmospheric dispersion model (POLAIR3D), and an application to heavy metals. Simulations are performed on a 4-year period in order to try to represent the inter-annual variability of atmospheric lead and cadmium concentrations. The next part reports the modelling of POPs which required the introduction of a soil model to address re-emissions. Results are compared with provided measurements. The fourth part reports the modelling of agricultural environments in the impact model, and more particularly physical processes and parameters proper to heavy metals and POPs. The author finally reports two case studies, one related to heavy metals, and the other to POPs [fr

  17. A Copper-Based Metal-Organic Framework as an Efficient and Reusable Heterogeneous Catalyst for Ullmann and Goldberg Type C–N Coupling Reactions

    Directory of Open Access Journals (Sweden)

    Wei Long

    2015-11-01

    Full Text Available A highly porous metal-organic framework (Cu-TDPAT, constructed from a paddle-wheel type dinuclear copper cluster and 2,4,6-tris(3,5-dicarboxylphenylamino-1,3,5-triazine (H6TDPAT, has been tested in Ullmann and Goldberg type C–N coupling reactions of a wide range of primary and secondary amines with halobenzenes, affording the corresponding N-arylation compounds in moderate to excellent yields. The Cu-TDPAT catalyst could be easily separated from the reaction mixtures by simple filtration, and could be reused at least five times without any significant degradation in catalytic activity.

  18. Preparation of γ-immunoglobulins coupled with DTPA and their labelling with trivalent metal radionuclides for radiotherapy

    International Nuclear Information System (INIS)

    Rekova, M.; Miler, V.; Budsky, F.; Malek, Z.; Prokop, J.; Prazak, Z.

    2007-06-01

    The scope of the report is as follows: immunoglobulin coupling with cDTPAA and labelling of the conjugate with 90 Y; Acid-base and complexation equilibria in the coupled immunoglobulin solution; Theory of the complex equilibrium of yttrium between coupled immunoglobulin and EDTA; and Procedures and results of recent experiments. The following was achieved: (i) The dependence of the bovine immunoglobulin on the cDTPAA/IgG coupling ratio and immunoglobulin concentration was obtained; (ii) A procedure aimed to free phosphate buffer from ubiquitous trivalent cations was tested; (iii) The procedure of lyophilization of coupled bovine IgG-DTPA in a phosphate buffer at pH 7.34 and I = 0.16 mol.l -1 .was elaborated. (iv) A procedure for lyophilization of the coupled CD20 monoclonal antibody in the same phosphate buffer was elaborated. (v) Acid-base and complexation equilibria were calculated for citrate and phosphate buffer solutions in the presence of coupled immunoglobulin. ( vi) A theory of the complexation equilibrium of yttrium between coupled immunoglobulin and EDTA was developed. (vii) Experiments were performed leading to the determination of a so far unknown constant of complexity of yttrium to DTPA coupled to immunoglobulin; its 3rd and 4th dissociation constants. (viii) The method sub (vii) can be applied to the determination of the complexity constants of other radionuclides with DTPA coupled to immunoglobulin; the 3rd and 4th dissociation constants of IgG-DTPA will not have to be sought any more. (ix) Samples of lyophilizate of the Y-CD20-DTPA complex can be sent to the biochemical laboratory for immunoreactivity determination. (x) Lyophilizates from experiments (iv-vi) are stored in a refrigerator at 4 deg C to be used for labelling with 177 Lu. (xi) The results obtained can be used to plan an experiment with CD20 in which a specific radioactivity of 400 MBq 177 Lu per mg CD20 will be achieved. (P.A.)

  19. Manganese(II), iron(II), and mixed-metal metal-organic frameworks based on chains with mixed carboxylate and azide bridges: magnetic coupling and slow relaxation.

    Science.gov (United States)

    Wang, Yan-Qin; Yue, Qi; Qi, Yan; Wang, Kun; Sun, Qian; Gao, En-Qing

    2013-04-15

    Mn(II) and Fe(II) compounds derived from azide and the zwitterionic 1-carboxylatomethylpyridinium-4-carboxylate ligand are isomorphous three-dimensional metal-organic frameworks (MOFs) with the sra net, in which the metal ions are connected into anionic chains by mixed (μ-1,1-azide)bis(μ-carboxylate) triple bridges and the chains are cross-linked by the cationic backbones of the zwitterionic ligands. The Mn(II) MOFs display typical one-dimensional antiferromagnetic behavior. In contrast, with one more d electron per metal center, the Fe(II) counterpart shows intrachain ferromagnetic interactions and slow relaxation of magnetization attributable to the single-chain components. The activation energies for magnetization reversal in the infinite- and finite-chain regimes are Δτ1 = 154 K and Δτ2 = 124 K, respectively. Taking advantage of the isomorphism between the Mn(II) and Fe(II) MOFs, we have prepared a series of mixed-metal Mn(II)(1-x)Fe(II)(x) MOFs with x = 0.41, 0.63, and 0.76, which intrinsically feature random isotropic/anisotropic sites and competing antiferromagnetic-ferromagnetic interactions. The materials show a gradual antiferromagnetic-to-ferromagnetic evolution in overall behaviors as the Fe(II) content increases, and the Fe-rich materials show complex relaxation processes that may arise for mixed SCM and spin-glass mechanisms. A general trend is that the activation energy and the blocking temperature increase with the Fe(II) content, emphasizing the importance of anisotropy for slow relaxation of magnetization.

  20. On the Folded Normal Distribution

    Directory of Open Access Journals (Sweden)

    Michail Tsagris

    2014-02-01

    Full Text Available The characteristic function of the folded normal distribution and its moment function are derived. The entropy of the folded normal distribution and the Kullback–Leibler from the normal and half normal distributions are approximated using Taylor series. The accuracy of the results are also assessed using different criteria. The maximum likelihood estimates and confidence intervals for the parameters are obtained using the asymptotic theory and bootstrap method. The coverage of the confidence intervals is also examined.

  1. Evaluation of sample preparation methods for the detection of total metal content using inductively coupled plasma optical emission spectrometry (ICP-OES) in wastewater and sludge

    Science.gov (United States)

    Dimpe, K. M.; Ngila, J. C.; Mabuba, N.; Nomngongo, P. N.

    Heavy metal contamination exists in aqueous wastes and sludge of many industrial discharges and domestic wastewater, among other sources. Determination of metals in the wastewater and sludge requires sample pre-treatment prior to analysis because of certain challenges such as the complexity of the physical state of the sample, which may lead to wrong readings in the measurement. This is particularly the case with low analyte concentration to be detected by the instrument. The purpose of this work was to assess and validate the different sample preparation methods namely, hot plate and microwave-assisted digestion procedures for extraction of metal ions in wastewater and sludge samples prior to their inductively coupled plasma optical emission spectrometric (ICP-OES) determination. For the extraction of As, Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn, three acid mixtures, that is, HNO3/H2O2, HNO3/HClO4/H2O2 and aqua regia + H2O2, were evaluated. Influent wastewater spiked with the SRM (CWW-TM-B) was used for the optimization of acid mixtures affecting the extraction procedure. After sample digestion, the filtration capabilities of cellulose-acetate filter paper and the acrodisc syringe filter with the pore size of 0.45 μm were compared. In terms of performance, acrodisc syringe filter in terms of the improved recoveries obtained, was found to be the best filtration method compared to the filter paper. Based on the analytical results obtained, microwave-assisted digestion (MAD) using aqua regia + H2O2 mixture was found to be the most suitable method for extraction of heavy metals and major elements in all the sample matrices. Therefore, MAD using aqua regia + H2O2 mixture was used for further investigations. The precision of the developed MAD method expressed in terms of relative standard deviations (% RSD) for different metals was found to be wastewater and sludge.

  2. Coupling of an electrodialyzer with inductively coupled plasma mass spectrometry for the on-line determination of trace impurities in silicon wafers after surface metal extraction.

    Science.gov (United States)

    Chang, I-long; Hsu, I-hsiang; Yang, Mo-hsiung; Sun, Yun-chang

    2010-02-19

    Understanding the properties that determine the distribution and behavior of trace impurities in Si wafers is critical to defining and controlling the performance, reliability, and yields of integrated microelectronic devices. It remains, however, an intrinsically difficult task to determine trace impurities in Si because of the minute concentrations and extremely high levels of matrix involved. In this study, we used an electrodialyzer for the simultaneous on-line removal of the silicate and acid matrices through the neutralization of the excessive hydrogen ion and selectively separation of acid and silicate ions by the combination of electrode reaction as a source of hydroxide ions with the anion exchange membrane separation. To retain the analyte ions in the sample stream, we found that the presence of moderate amounts of nitric acid and hydrazine were necessary to improve the retention efficiency, not only for Zn(2+), Ni(2+), Cu(2+), and Co(2+) ions but also for CrO(4)(2-) ion. Under the optimized conditions, the interference that resulted from the sample matrix was suppressed significantly to provide satisfactory analytical signals. The precision of this method was ca. 5% when we used an electrodialyzer equipped with an anion exchange membrane to remove the sample matrix prior to performing inductively coupled plasma mass spectrometry (ICP-MS); the good agreement between the data obtained using our proposed method and those obtained using a batchwise wet chemical technique confirmed its accuracy. Our method permits the determination of Zn, Ni, Cu, Co, and Cr in Si wafers at detection limits within the range from 2.2 x 10(15) to 9.0 x 10(15) atoms cm(-3). Copyright 2009 Elsevier B.V. All rights reserved.

  3. Selective coupling of HE11 and TM01 modes into microfabricated fully metal-coated quartz probes

    International Nuclear Information System (INIS)

    Tortora, P.; Descrovi, E.; Aeschimann, L.; Vaccaro, L.; Herzig, H.-P.; Daendliker, R.

    2007-01-01

    We report computational and experimental investigations on injection and transmission of light in microfabricated fully Aluminum-coated quartz probes. In particular, we show that a selective coupling of either the HE 11 or the TM 01 mode can be carried out by injecting focused linearly or radially polarized beams into the probe. Optical fields, emitted by the probe after a controlled injection, are characterized in intensity and phase with the help of an interferometric technique. With the help of near-field measurement, we finally demonstrate that a longitudinally polarized spot localized at the tip apex is actually produced when the TM 01 mode is coupled into the probe

  4. Study on the heavy metal bioconcentrations of the Shadegan international wetland mosquitofish, Gambusia affinis, by inductively coupled plasma technique

    Science.gov (United States)

    2013-01-01

    The purpose of this study was to evaluate the levels of heavy metal bioconcentration of the mosquitofish (Gambusia affinis) in Shadegan international wetland. Sampling including the water, waterbed sediment and mosquitofish was carried out from the selected sampling sites during October and November 2011, and analyzed by the ICP-OES. Results show that the water has poor qualitative condition, according to EPA and WHO water quality standards. The level of the water Cr in the selected sites in both months and the levels of Fe, Mn and Zn during October in the SW1 site were higher than the instrumental detection limits indicating that the water was contaminated with these metals in the mentioned sites and months. The levels of the waterbed sediment As, Co, Cr, Cu, Fe, Mn, Pb and Zn, and mosquitofish Cr, Cu, Fe, Mn, Zn, Co and Cd were much higher than the instrumental detection limits, indicating that the waterbed sediment and mosquitofish were contaminated with them during October and November in the selected sites. Statistical assessments reveal that there is a significant difference between the mentioned contaminated water, waterbed sediment and mosquitofish heavy metals (all P-values bioindicator of heavy metal pollution in marine ecosystems such as wetlands. PMID:24499681

  5. Chiral-Selective Formation of 1D Polymers Based on Ullmann-Type Coupling : The Role of the Metallic Substrate

    NARCIS (Netherlands)

    Pham, Tuan Anh; Tran, Van Bay; Nguyen, Manh-Thuong; Stöhr, Meike

    2017-01-01

    The chiral-selective formation of 1D polymers from a prochiral molecule, namely, 6,12-dibromochrysene in dependence of the type of metal surface is demonstrated by a combined scanning tunneling microscopy and density functional theory study. Deposition of the chosen molecule on Au(111) held at room

  6. Spontaneous emission spectra and quantum light-matter interactions from a strongly coupled quantum dot metal-nanoparticle system

    DEFF Research Database (Denmark)

    Van Vlack, C.; Kristensen, Philip Trøst; Hughes, S.

    2012-01-01

    the dot to the detector, we demonstrate that the strong-coupling regime should be observable in the far-field spontaneous emission spectrum, even at room temperature. The vacuum-induced emission spectra show that the usual vacuum Rabi doublet becomes a rich spectral triplet or quartet with two of the four...

  7. Study on the Heavy Metal Bioconcentrations of the Shadegan International Wetland Mosquitofish, Gambusia Affinis, by Inductively Coupled Plasma Technique

    Directory of Open Access Journals (Sweden)

    Hassan Nasirian

    2013-07-01

    Full Text Available The purpose of this study was to evaluate the levels of heavy metal bioconcentration of the mosquitofish (Gambusia affinis in Shadegan international wetland. Sampling including the water, waterbed sediment and mosquitofish was carried out from the selected sampling sites during October and November 2011, and analyzed by the ICP-OES. Results show that the water has poor qualitative condition, according to EPA and WHO water quality standards. The level of the water Cr in the selected sites in both months and the levels of Fe, Mn and Zn during October in the SW1 site were higher than the instrumental detection limits indicating that the water was contaminated with these metals in the mentioned sites and months. The levels of the waterbed sediment As, Co, Cr, Cu, Fe, Mn, Pb and Zn, and mosquitofish Cr, Cu, Fe, Mn, Zn, Co and Cd were much higher than the instrumental detection limits, indicating that the waterbed sediment and mosquitofish were contaminated with them during October and November in the selected sites. Statistical assessments reveal that there is a significant difference between the mentioned contaminated water, waterbed sediment and mosquitofish heavy metals (all P-values < 0.05. In overall, it is considered that the contaminated heavy metals can be accumulated in the waterbed sediment and bioconcentrated in the wildlife tissues, then finally can be entered in the marine food chains and biomagnified there after long periods. In conclusion, this paper confirmed that the G. affinis can be used as a bioindicator of heavy metal pollution in marine ecosystems such as wetlands

  8. Determination of heavy metals and their speciation in street dusts by inductively coupled plasma-optical emission spectrometry after a Community Bureau of Reference sequential extraction procedure.

    Science.gov (United States)

    Altundag, Huseyin; Imamoglu, Mustafa; Doganci, Secil; Baysal, Erkan; Albayrak, Sinem; Tuzen, Mustafa

    2013-01-01

    Sequential selective extraction techniques are commonly used to fractionate the solid-phase forms of metals in soils. This procedure provides measurements of extractable metals from media, such as acetic acid (0.11 M), hydroxyl ammonium chloride (0.1 M), hydrogen peroxide (8.8 M) plus ammonium acetate (1 M), and aqua regia stages of the sequential extraction procedure. In this work, the extractable Pb, Cu, Mn, Sr, Ni, V, Fe, Zn, and Cr were evaluated in street dust samples from Sakarya, Turkey, between May and October 2009 using the three-step sequential extraction procedure described by the Community Bureau of Reference (BCR, now the Standards, Measurements, and Testing Programme) of the European Union. The sampling sites were divided into 10 categories; a total of 50 street dusts were analyzed. The determination of multielements in the samples was performed by inductively coupled plasma-optical emission spectrometry. Validation of the proposed method was performed using BCR 701 certified reference material. The results showed good agreement between the obtained and the certified values for the metals analyzed.

  9. Spin-memory loss due to spin-orbit coupling at ferromagnet/heavy-metal interfaces: Ab initio spin-density matrix approach

    Science.gov (United States)

    Dolui, Kapildeb; Nikolić, Branislav K.

    2017-12-01

    Spin-memory loss (SML) of electrons traversing ferromagnetic-metal/heavy-metal (FM/HM), FM/normal-metal (FM/NM), and HM/NM interfaces is a fundamental phenomenon that must be invoked to explain consistently large numbers of spintronic experiments. However, its strength extracted by fitting experimental data to phenomenological semiclassical theory, which replaces each interface by a fictitious bulk diffusive layer, is poorly understood from a microscopic quantum framework and/or materials properties. Here we describe an ensemble of flowing spin quantum states using spin-density matrix, so that SML is measured like any decoherence process by the decay of its off-diagonal elements or, equivalently, by the reduction of the magnitude of polarization vector. By combining this framework with density functional theory, we examine how all three components of the polarization vector change at Co/Ta, Co/Pt, Co/Cu, Pt/Cu, and Pt/Au interfaces embedded within Cu/FM/HM/Cu vertical heterostructures. In addition, we use ab initio Green's functions to compute spectral functions and spin textures over FM, HM, and NM monolayers around these interfaces which quantify interfacial spin-orbit coupling and explain the microscopic origin of SML in long-standing puzzles, such as why it is nonzero at the Co/Cu interface; why it is very large at the Pt/Cu interface; and why it occurs even in the absence of disorder, intermixing and magnons at the interface.

  10. Selective Synthesis of Gasoline-Ranged Hydrocarbons from Syngas over Hybrid Catalyst Consisting of Metal-Loaded ZSM-5 Coupled with Copper-Zinc Oxide

    Directory of Open Access Journals (Sweden)

    Ting Ma

    2014-04-01

    Full Text Available The conversion of syngas (CO + H2 to gasoline-ranged hydrocarbons was carried out using a hybrid catalyst consisting of metal-loaded ZSM-5 coupled with Cu-ZnO in a near-critical n-hexane solvent. Methanol was synthesized from syngas over Cu-ZnO; subsequently, was converted to hydrocarbons through the formation of dimethyl ether (DME over the metal-loaded ZSM-5. When 0.5 wt% Pd/ZSM-5 and 5 wt% Cu/ZSM-5 among the metal-loaded ZSM-5 catalysts with Pd, Co, Fe or Cu were employed as a portion of the hybrid catalyst, the gasoline-ranged hydrocarbons were selectively produced (the gasoline-ranged hydrocarbons in all hydrocarbons: 59% for the hybrid catalyst with Pd/ZSM-5 and 64% for that with Cu/ZSM-5 with a similar CO conversion during the reaction. An increase in the Cu loading on ZSM-5 resulted in increasing the yield of the gasoline-ranged hydrocarbons, and in decreasing the yield of DME. Furthermore, the hybrid catalyst with Cu/ZSM-5 exhibited no deactivation for 30 h of the reaction. It was revealed that a hybrid catalyst containing Cu/ZSM-5 was efficient in the selective synthesis of gasoline-ranged hydrocarbons from syngas via methanol in the near-critical n-hexane fluid.

  11. Examining Heavy Metals in Acid Mine Drainage Wetlands in Western Pennsylvania through the use of Inductively Coupled Plasma Optical Emission Spectroscopy and Drone Aerial Photography.

    Science.gov (United States)

    Santoro, N.; Mount, G.

    2017-12-01

    Acid mine drainage (AMD) emanating from three abandoned mines feed an estimated 126 pounds of iron per day into the Tanoma remediation wetlands located in Tanoma, Pennsylvania. Along with the iron released into the system, 1500-2800 gallons of AMD per minute is seasonally discharged into the passive system. This high rate of discharge produces areas of high velocity flow that scour the wetland bottom moving precipitants and destroying vegetation roots. Although the discharge into Tanoma is known to be damaging, other discharges to surface waters have shown iron and heavy metal concentrations several times higher, and are left untreated to enter reservoir systems. This draws attention to these remediation sites, the processes used to treat them, and the effectiveness of each site. With most of the research that's been conducted in the AMD remediation field relating to in-lab experiments on iron concentrations, there is very little information in the literature about the effects of these large influxes of heavy metals and the effects it has on the biodiversity and methane production within a AMD remediation site. This research investigates the presence and concentration of heavy metals with the treatment wetland and other surface water sources using inductively coupled plasma optical emission spectroscopy (ICP-OES) and drone based aerial photography. Furthermore, our ICP data is compared with biodiversity patterns and methane levels within the Tanoma AMD site to identify relationships and the potential effect they have on the productivity and effectiveness of the remediation site through time.

  12. Analysis of atmospheric pollutant metals by laser ablation inductively coupled plasma mass spectrometry with a radial line-scan dried-droplet approach

    Science.gov (United States)

    Tang, Xiaoxing; Qian, Yuan; Guo, Yanchuan; Wei, Nannan; Li, Yulan; Yao, Jian; Wang, Guanghua; Ma, Jifei; Liu, Wei

    2017-12-01

    A novel method has been improved for analyzing atmospheric pollutant metals (Be, Mn, Fe, Co, Ni, Cu, Zn, Se, Sr, Cd, and Pb) by laser ablation inductively coupled plasma mass spectrometry. In this method, solid standards are prepared by depositing droplets of aqueous standard solutions on the surface of a membrane filter, which is the same type as used for collecting atmospheric pollutant metals. Laser parameters were optimized, and ablation behaviors of the filter discs were studied. The mode of radial line scans across the filter disc was a representative ablation strategy and can avoid error from the inhomogeneous filter standards and marginal effect of the filter disc. Pt, as the internal standard, greatly improved the correlation coefficient of the calibration curve. The developed method provides low detection limits, from 0.01 ng m- 3 for Be and Co to 1.92 ng m- 3 for Fe. It was successfully applied for the determination of atmospheric pollutant metals collected in Lhasa, China. The analytical results showed good agreement with those obtained by conventional liquid analysis. In contrast to the conventional acid digestion procedure, the novel method not only greatly reduces sample preparation and shortens the analysis time but also provides a possible means for studying the spatial distribution of atmospheric filter samples.

  13. Resonant excitation of coupled Rayleigh waves in a short and narrow fluid channel clad between two identical metal plates

    Directory of Open Access Journals (Sweden)

    Victor M. García-Chocano

    2011-12-01

    Full Text Available Transmission of ultrasonic waves through a slit between two water immersed brass plates is studied for sub-wavelength plate thicknesses and slit apertures. Extraordinary high absorption is observed at discrete frequencies corresponding to resonant excitation of Rayleigh waves on the both sides of the channel. The coupling of the Rayleigh waves occurs through the fluid and the corresponding contribution to the dispersion has been theoretically derived and also experimentally confirmed. Symmetric and anti-symmetric modes are predicted but only the symmetric mode resonances have been observed. It follows from the dispersion equation that the coupled Rayleigh waves cannot be excited in a channel with apertures less than the critical one. The calculated critical aperture is in a good agreement with the measured acoustic spectra. These findings could be applied to design a broadband absorptive metamaterial.

  14. NoFold: RNA structure clustering without folding or alignment.

    Science.gov (United States)

    Middleton, Sarah A; Kim, Junhyong

    2014-11-01

    Structures that recur across multiple different transcripts, called structure motifs, often perform a similar function-for example, recruiting a specific RNA-binding protein that then regulates translation, splicing, or subcellular localization. Identifying common motifs between coregulated transcripts may therefore yield significant insight into their binding partners and mechanism of regulation. However, as most methods for clustering structures are based on folding individual sequences or doing many pairwise alignments, this results in a tradeoff between speed and accuracy that can be problematic for large-scale data sets. Here we describe a novel method for comparing and characterizing RNA secondary structures that does not require folding or pairwise alignment of the input sequences. Our method uses the idea of constructing a distance function between two objects by their respective distances to a collection of empirical examples or models, which in our case consists of 1973 Rfam family covariance models. Using this as a basis for measuring structural similarity, we developed a clustering pipeline called NoFold to automatically identify and annotate structure motifs within large sequence data sets. We demonstrate that NoFold can simultaneously identify multiple structure motifs with an average sensitivity of 0.80 and precision of 0.98 and generally exceeds the performance of existing methods. We also perform a cross-validation analysis of the entire set of Rfam families, achieving an average sensitivity of 0.57. We apply NoFold to identify motifs enriched in dendritically localized transcripts and report 213 enriched motifs, including both known and novel structures. © 2014 Middleton and Kim; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

  15. Heavy metal removal from MSWI fly ash by electrokinetic remediation coupled with a permeable activated charcoal reactive barrier

    Science.gov (United States)

    Huang, Tao; Li, Dongwei; Kexiang, Liu; Zhang, Yuewei

    2015-10-01

    This paper presents the investigations into the feasibility of the application of a remediation system that couples electrokinetic remediation (EKR) with the permeable reactive barrier (PRB) concept for municipal solid waste incineration (MSWI) fly ash with activated charcoal as the PRB material. The experimental results of this study showed that the proposed combined method can effectively improve the remediation efficiency and that the addition of the oxalic acid to the PRB media before the coupled system can further enhance the remediation process. In the optimization tests, the maximum removals of Zn, Pb, Cu and Cd were achieved under different experimental conditions. The voltage gradient and processing time were shown to have significant effects on the removal of Cu and Cd, whereas the addition of the oxalic acid had a more significant influence on the removal of Pb. Generally, the processing time is the most significant factor in changing the removal rates of HMs in the enhanced coupled system. In terms of the leaching toxicity, the specimen remediated by ENEKR + PRB showed the lowest leaching value for each HM in the S2 and S3 regions.

  16. Assessment of heavy metal contamination in core sediment samples in Gulf of Izmir, Aegean Sea, Turkey (by inductively coupled plasma-optical emission spectrometry (ICP-OES))

    Science.gov (United States)

    Ünal Yumun, Zeki; Kam, Erol; Kurt, Dilek

    2017-04-01

    Heavy metal and radionuclide analysis studies are crucial in explaining biotic and abiotic interactions in ecosystems. This type of analysis is highly needed in environments such as coastal areas, gulfs or lakes where human activities are generally concentrated. Sediments are one of the best biological indicators for the environment since the pollution accumulates in the sediments by descent to the sea floor. In this study, sediments were collected from the Gulf of Izmir (Eastern Aegean Sea, Turkey) considering the accumulated points of domestic and industrial wastes to make an anthropogenic pollution analysis. The core sediments had different depths of 0.00-30.00 m at four different locations where Karsiyaka, Bayrakli, Incialti and Cesmealti in the Gulf of Izmir. The purpose of the study was determining Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn concentrations in the drilling samples to assess their levels and spatial distribution in crucial areas of the Aegean Sea by inductively coupled plasma-optical emission spectrometry (ICP-OES) with microwave digestion techniques. The heavy metal concentrations found in sediments varied for Cd: metals. Keywords: Gulf of Izmir, heavy metals, ICP-OES, pollution, sediment.

  17. A dipole-assisted solid-phase extraction microchip combined with inductively coupled plasma-mass spectrometry for online determination of trace heavy metals in natural water.

    Science.gov (United States)

    Shih, Tsung-Ting; Hsu, I-Hsiang; Chen, Shun-Niang; Chen, Ping-Hung; Deng, Ming-Jay; Chen, Yu; Lin, Yang-Wei; Sun, Yuh-Chang

    2015-01-21

    We employed a polymeric material, poly(methyl methacrylate) (PMMA), for fabricating a microdevice and then implanted the chlorine (Cl)-containing solid-phase extraction (SPE) functionality into the PMMA chip to develop an innovative on-chip dipole-assisted SPE technique. Instead of the ion-ion interactions utilized in on-chip SPE techniques, the dipole-ion interactions between the highly electronegative C-Cl moieties in the channel interior and the positively charged metal ions were employed to facilitate the on-chip SPE procedures. Furthermore, to avoid labor-intensive manual manipulation, a programmable valve manifold was designed as an interface combining the dipole-assisted SPE microchip and inductively coupled plasma-mass spectrometry (ICP-MS) to achieve the fully automated operation. Under the optimized operation conditions for the established system, the detection limits for each analyte ion were obtained based on three times the standard deviation of seven measurements of the blank eluent solution. The limits ranged from 3.48 to 20.68 ng L(-1), suggesting that this technique appears uniquely suited for determining the levels of heavy metal ions in natural water. Indeed, a series of validation procedures demonstrated that the developed method could be satisfactorily applied to the determination of trace heavy metals in natural water. Remarkably, the developed device was durable enough to be reused more than 160 times without any loss in its analytical performance. To the best of our knowledge, this is the first study reporting on the combination of a dipole-assisted SPE microchip and elemental analysis instrument for the online determination of trace heavy metal ions.

  18. Understanding the folding process of synthetic polymers by small ...

    Indian Academy of Sciences (India)

    WINTEC

    *For correspondence. Understanding the folding process of synthetic polymers by ... Conformational control in biological macromole- cules depends largely ... context of sensors. 11–13 and more recently with regard to foldamers. 14–17. In these systems, the com- plexation of the OE segment by a metal-ion leads to either a ...

  19. Manipulating Micellar Environments for Enhancing Transition Metal-Catalyzed Cross-Couplings in Water at Room Temperature

    Science.gov (United States)

    Ghorai, Subir; Leong, Wendy Wen Yi; Taft, Benjamin R.; Krogstad, Daniel V.

    2012-01-01

    The remarkable effects of added salts on the properties of aqueous micelles derived from the amphiphile PTS are described. Most notably Heck reactions run in the presence of NaCl lead to couplings on aryl bromides in water at room temperature. Olefin cross- and ring-closing metathesis reactions run in the presence of small amounts of pH-lowering KHSO4 are also accelerated, another phenomenon that does not apply to typical processes in organic media. These salt effects allow, in general, for synthetically valuable C-C bond-forming processes to be conducted under environmentally benign conditions. Recycling of the surfactant is also demonstrated. PMID:21539384

  20. Highly efficient transition metal-free coupling of acid chlorides with terminal alkynes in [bmim]Br: A rapid route to access ynones using MgCl2

    Directory of Open Access Journals (Sweden)

    Mohammad Navid Soltani Rad

    2018-03-01

    Full Text Available A simple, mild, highly efficient and transition metal-free protocol for synthesis of ynones in an ionic liquid is described. In this approach, the coupling reaction of different acid chlorides with terminal alkynes was efficiently carried out using 0.05 mol% MgCl2 in the presence of triethylamine in [bmim]Br at room temperature to afford the corresponding ynones in good to excellent yields. This method is highly efficient for various acid chlorides and alkynes including aliphatic, aromatic, and heteroaromatic substrates bearing different functional groups. The influence of some parameters in this reaction including type of ionic liquid, base and catalyst has been discussed.

  1. Distribution of Heavy Metals in Core Marine Sediments of Coastal East Malaysia by Instrumental Neutron Activation Analysis and Inductively Coupled Plasma Spectroscopy.

    Science.gov (United States)

    Ashraf, Ahmadreza; Saion, Elias; Gharibshahi, Elham; Yap, Chee Kong; Kamari, Halimah Mohamed; Elias, Md Suhaimi; Rahman, Shamsiah Abdul

    2018-02-01

    Fifty-five core marine sediments from three locations at South China Sea and one location each at Sulu Sea and Sulawesi Sea of coastal East Malaysia were analyzed for heavy metals by instrumental neutron activation analysis and inductively coupled plasma mass spectroscopy. The enrichment factor and the modified degree of contamination were used to calculate the anthropogenic and pollution status of the elements in the samples. The enrichment factor of As, Cd, Cr, Cu, Ni, Pb, and Zn varied from 0.42-4.26, 0.50-2.34, 0.31-0.82, 0.20-0.61, 0.91-1.92, 0.23-1.52, and 0.90-1.28, respectively, with the modified degree of contamination values below 0.6. Comparative data showed that coastal East Malaysia has low levels of contamination. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Characterisation of a 3 kW PEFC power system coupled with a metal hydride H 2 storage

    Science.gov (United States)

    Bossi, C.; Del Corno, A.; Scagliotti, M.; Valli, C.

    Fuel cells and hydrogen storages, eventually integrated in hybrid power systems with hydrogen production from renewables, represent an interesting option for small stationary applications such as power generation in remote sites beyond the grid or back up power for telecom stations. This paper deals with the CESI RICERCA experiences on a polymer electrolyte fuel cell (PEFC) power system fuelled with the hydrogen supplied by a metal hydride storage. The power system consists of three ReliOn Independence 1000 PEFC units, a battery bank and a 3.3 kWe DC-AC converter (inverter). The hydrogen storage is made of LaNi 5 type powders and can supply more than 6 Nm 3 of hydrogen per discharge cycle. The PEFC units, the inverter and the hydrogen storage performances were characterised. These subsystems were integrated into an automated power generation system and connected to a local grid including other power generators, power quality analysers, energy storage systems and electrical loads. The main features of the integrated system are analysed herein. In particular the overall system stability upon cycling, the heat transfer issues and the possibility of recovering the fuel cell waste heat to extract hydrogen from the metal hydrides are discussed. Finally, during grid-connected operations, the power quality indexes were measured and found in agreement with the EN 50160 standard.

  3. Fluorescence of Alexa fluor dye tracks protein folding.

    Directory of Open Access Journals (Sweden)

    Simon Lindhoud

    Full Text Available Fluorescence spectroscopy is an important tool for the characterization of protein folding. Often, a protein is labeled with appropriate fluorescent donor and acceptor probes and folding-induced changes in Förster Resonance Energy Transfer (FRET are monitored. However, conformational changes of the protein potentially affect fluorescence properties of both probes, thereby profoundly complicating interpretation of FRET data. In this study, we assess the effects protein folding has on fluorescence properties of Alexa Fluor 488 (A488, which is commonly used as FRET donor. Here, A488 is covalently attached to Cys69 of apoflavodoxin from Azotobacter vinelandii. Although coupling of A488 slightly destabilizes apoflavodoxin, the three-state folding of this protein, which involves a molten globule intermediate, is unaffected. Upon folding of apoflavodoxin, fluorescence emission intensity of A488 changes significantly. To illuminate the molecular sources of this alteration, we applied steady state and time-resolved fluorescence techniques. The results obtained show that tryptophans cause folding-induced changes in quenching of Alexa dye. Compared to unfolded protein, static quenching of A488 is increased in the molten globule. Upon populating the native state both static and dynamic quenching of A488 decrease considerably. We show that fluorescence quenching of Alexa Fluor dyes is a sensitive reporter of conformational changes during protein folding.

  4. Fluorescence of Alexa fluor dye tracks protein folding.

    Science.gov (United States)

    Lindhoud, Simon; Westphal, Adrie H; Visser, Antonie J W G; Borst, Jan Willem; van Mierlo, Carlo P M

    2012-01-01

    Fluorescence spectroscopy is an important tool for the characterization of protein folding. Often, a protein is labeled with appropriate fluorescent donor and acceptor probes and folding-induced changes in Förster Resonance Energy Transfer (FRET) are monitored. However, conformational changes of the protein potentially affect fluorescence properties of both probes, thereby profoundly complicating interpretation of FRET data. In this study, we assess the effects protein folding has on fluorescence properties of Alexa Fluor 488 (A488), which is commonly used as FRET donor. Here, A488 is covalently attached to Cys69 of apoflavodoxin from Azotobacter vinelandii. Although coupling of A488 slightly destabilizes apoflavodoxin, the three-state folding of this protein, which involves a molten globule intermediate, is unaffected. Upon folding of apoflavodoxin, fluorescence emission intensity of A488 changes significantly. To illuminate the molecular sources of this alteration, we applied steady state and time-resolved fluorescence techniques. The results obtained show that tryptophans cause folding-induced changes in quenching of Alexa dye. Compared to unfolded protein, static quenching of A488 is increased in the molten globule. Upon populating the native state both static and dynamic quenching of A488 decrease considerably. We show that fluorescence quenching of Alexa Fluor dyes is a sensitive reporter of conformational changes during protein folding.

  5. Investigation into the behavior of metal-argon polyatomic ions (MAr+) in the extraction region of inductively coupled plasma-mass spectrometry

    International Nuclear Information System (INIS)

    Ebert, Chris H.; Witte, Travis M.; Houk, R.S.

    2012-01-01

    The abundances of metal-argon polyatomic ions (MAr + ) are determined in inductively coupled plasma-mass spectrometry (ICP-MS). The ratios of MAr + abundance to that for M + ions are measured experimentally. These ratios are compared to expected values, calculated for typical plasma conditions using spectroscopic data. For all metals studied (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn), the measured ratios are significantly lower than the calculated ratios. Increasing the plasma potential (and thereby increasing the ion kinetic energy) by means of a homemade guard electrode with a wide gap further reduces the MAr + /M + ratio. Implementing a skimmer cone designed for high transmission of light ions increases the MAr + abundance. Considering this evidence, the scarcity of MAr + ions is attributed to collision induced dissociation (CID), likely due to a shock wave at the tip of or in the throat of the skimmer cone. - Highlights: ► MAr + ions are less abundant in the mass spectrum than expected from the ICP. ► Increasing the plasma potential reduces their abundance further. ► The extraction lens voltage does not greatly affect the MAr + abundances. ► The weakly-bound MAr + ions are probably dissociated by collisions during extraction.

  6. Simultaneous determination of carbohydrates, carboxylic acids, alcohols, and metals in foods by high-performance liquid chromatography inductively coupled plasma atomic emission spectrometry.

    Science.gov (United States)

    Paredes, Eduardo; Maestre, Salvador E; Prats, Soledad; Todolí, José L

    2006-10-01

    The applicability of the HPLC-ICP-AES coupling for the simultaneous determination of carbohydrates, carboxylic acids, alcohols, and metals in a single chromatographic run has been demonstrated in the present work. Five saccharides, glucose, fructose, sucrose, sorbitol, and lactose; five carboxylic acids, citric, tartaric, malic, lactic, and acetic; and three alcohols, glycerol, ethanol, and methanol, have been determined. A H+ cation exchange column has been used to separate these compounds. The chromatograms have been obtained by monitoring the carbon emission signal at 193.09 nm. The results obtained by HPLC-ICP-AES have been compared against those found with conventional detection systems (i.e., refractive index, UV, and photodyode array detectors). The HPLC-ICP-AES method has shown the following features: (i) organic compounds and metals can be simultaneously determined; (ii) the detection method is universal; (iii) for nonvolatile organic compounds, a complete calibration line can be obtained from a single injection; and (iv) it provides absolute limits of detection similar to or lower than those found with conventional detection systems (i.e., on the order of several tens of nanograms of organic compound). The methodology has been validated through the analysis of food samples such as juices, isotonic beverages, wines, and a certified nonfat milk powder sample.

  7. Method validation for determination of metals in Vitis labrusca L. grapevine leaf extracts by inductively coupled plasma mass spectrometry (ICP-MS

    Directory of Open Access Journals (Sweden)

    LIANE V.V. BOKOWSKI

    Full Text Available ABSTRACT Vitis labrusca L. is the main species used for wine and juice production in Brazil. The grapevine leaves can be used both as functional foods and as cheapest sources for the extraction of phenolic compounds. Besides the antioxidant activity, grapevine leaves exhibited significant anti-inflammatory activity. Therefore, the aim of this study was to develop and validate an analytical methodology to determine the metals selenium (96Se, chromium (53Cr, nickel (62Ni, cadmium (111Cd and lead (206Pb in 30 samples of grapevine leaf extracts (Vitis labrusca, Bordo cultivar using inductively coupled plasma mass spectrometry (ICP-MS. To obtain the grapevine leaf extracts the samples were milled, weighed and digested in microwave oven with nitric acid. The method showed linearity, precision, accuracy and limits of quantification and detection acceptable for INMETRO protocol validation of analytical methods. Therefore, the method using ICP-MS was developed and validated to determine metals concentrations in grapevine leaves of Vitis labrusca L. and the proposed method could be applied in routine analytical laboratory.

  8. Determination of Metals Present in Textile Dyes Using Laser-Induced Breakdown Spectroscopy and Cross-Validation Using Inductively Coupled Plasma/Atomic Emission Spectroscopy

    Directory of Open Access Journals (Sweden)

    K. Rehan

    2017-01-01

    Full Text Available Laser-induced breakdown spectroscopy (LIBS was used for the quantitative analysis of elements present in textile dyes at ambient pressure via the fundamental mode (1064 nm of a Nd:YAG pulsed laser. Three samples were collected for this purpose. Spectra of textile dyes were acquired using an HR spectrometer (LIBS2000+, Ocean Optics, Inc. having an optical resolution of 0.06 nm in the spectral range of 200 to 720 nm. Toxic metals like Cr, Cu, Fe, Ni, and Zn along with other elements like Al, Mg, Ca, and Na were revealed to exist in the samples. The %-age concentrations of the detected elements were measured by means of standard calibration curve method, intensities of every emission from every species, and calibration-free (CF LIBS approach. Only Sample 3 was found to contain heavy metals like Cr, Cu, and Ni above the prescribed limit. The results using LIBS were found to be in good agreement when compared to outcomes of inductively coupled plasma/atomic emission spectroscopy (ICP/AES.

  9. Hydrogen production coupled to nuclear waste treatment: the safe treatment of alkali metals through a well-demonstrated process

    International Nuclear Information System (INIS)

    Rahier, A.; Mesrobian, G.

    2006-01-01

    In 1992, the United Nations emphasised the urgent need to act against the perpetuation of disparities between and within nations, the worsening of poverty, hunger, ill health and illiteracy and the continuing deterioration of ecosystems on which we depend for our well-being. In this framework, taking into account the preservation of both worldwide energy resources and ecosystems, the use of nuclear energy to produce clean energy carriers, such as hydrogen, is undoubtedly advisable. However, coping fully with the Agenda 21 statements requires defining adequate treatment processes for nuclear wastes. This paper discusses the possible use of a well-demonstrated process to convert radioactively contaminated alkali metals into sodium hydroxide while producing hydrogen. We conclude that a synergy between Chlor-Alkali specialists and nuclear specialists may help find an acceptable solution for radioactively contaminated sodium waste. (author)

  10. Rational Design of Mixed-Metal Oxides for Chemical Looping Combustion of Coal via Coupled Computational-Experimental Studies

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, Amit; Li, Fanxing; Santiso, Erik

    2017-09-18

    Energy and global climate change are two grand challenges to the modern society. An urgent need exists for development of clean and efficient energy conversion processes. The chemical looping strategy, which utilizes regenerable oxygen carriers (OCs) to indirectly convert carbonaceous fuels via redox reactions, is considered to be one of the more promising approaches for CO2 capture by the U.S. Department of Energy (USDOE). To date, most long-term chemical looping operations were conducted using gaseous fuels, even though direct conversion of coal is more desirable from both economics and CO2 capture viewpoints. The main challenges for direct coal conversion reside in the stringent requirements on oxygen carrier performances. In addition, coal char and volatile compounds are more challenging to convert than gaseous fuels. A promising approach for direct conversion of coal is the so called chemical looping with oxygen uncoupling (CLOU) technique. In the CLOU process, a metal oxide that decomposes at the looping temperature, and releases oxygen to the gas phase is used as the OC. The overarching objective of this project was to discover the fundamental principles for rational design and optimization of oxygen carriers (OC) in coal chemical looping combustion (CLC) processes. It directly addresses Topic Area B of the funding opportunity announcement (FOA) in terms of “predictive description of the phase behavior and mechanical properties” of “mixed metal oxide” based OCs and rational development of new OC materials with superior functionality. This was achieved through studies exploring i) iron-containing mixed-oxide composites as oxygen carriers for CLOU, ii) Ca1-xAxMnO3-δ (A = Sr and Ba) as oxygen carriers for CLOU, iii) CaMn1-xBxO3-δ (B=Al, V, Fe, Co, and Ni) as oxygen carrier for CLOU and iv) vacancy creation energy in Mn-containing perovskites as an indicator chemical looping with oxygen uncoupling.

  11. Fabrication and characterization of coupled ensembles of epitaxial quantum dots and metal nanoparticles supporting localized surface plasmons

    Science.gov (United States)

    Kosarev, Alexander; Chaldyshev, Vladimir; Toropov, Nikita; Gladskikh, Igor; Gladskikh, Polina; Baryshnikova, Kseniia; Preobrazhenskiy, Valeriy; Putyato, Michael; Semyagin, Boris; Vartanyan, Tigran

    2017-08-01

    A stack of five layers of epitaxial InAs QDs with GaAs barriers was grown by molecular-beam epitaxy. The upper layer of QDs was capped by 3nm-GaAs/3nm-AlAs/4nm-GaAs layer sequence. Then, a thin silver layer was added via physical vapor deposition. After annealing isolated silver nanoparticles were formed above the layer of buried InAs quantum dots. We studied interplay of the exciton resonance in InAs QDs and plasmon resonance in Ag nanoparticles. In particular, we observed more than twofold enhancement of the exciton photoluminescence intensity from the InAs QDs when they were coupled to the silver nanoparticles.

  12. Protein folding and wring resonances

    DEFF Research Database (Denmark)

    Bohr, Jakob; Bohr, Henrik; Brunak, Søren

    1997-01-01

    The polypeptide chain of a protein is shown to obey topological contraints which enable long range excitations in the form of wring modes of the protein backbone. Wring modes of proteins of specific lengths can therefore resonate with molecular modes present in the cell. It is suggested...... that protein folding takes place when the amplitude of a wring excitation becomes so large that it is energetically favorable to bend the protein backbone. The condition under which such structural transformations can occur is found, and it is shown that both cold and hot denaturation (the unfolding...... of proteins) are natural consequences of the suggested wring mode model. Native (folded) proteins are found to possess an intrinsic standing wring mode....

  13. Multiview Rectification of Folded Documents.

    Science.gov (United States)

    You, Shaodi; Matsushita, Yasuyuki; Sinha, Sudipta; Bou, Yusuke; Ikeuchi, Katsushi

    2018-02-01

    Digitally unwrapping images of paper sheets is crucial for accurate document scanning and text recognition. This paper presents a method for automatically rectifying curved or folded paper sheets from a few images captured from multiple viewpoints. Prior methods either need expensive 3D scanners or model deformable surfaces using over-simplified parametric representations. In contrast, our method uses regular images and is based on general developable surface models that can represent a wide variety of paper deformations. Our main contribution is a new robust rectification method based on ridge-aware 3D reconstruction of a paper sheet and unwrapping the reconstructed surface using properties of developable surfaces via conformal mapping. We present results on several examples including book pages, folded letters and shopping receipts.

  14. Equi-Gaussian curvature folding

    Indian Academy of Sciences (India)

    curvature kf (p) i.e., kp = kf (p). In this case f will map curves to curves with equal equi-. Gaussian curvature at corresponding points. It will also map area with sectional curvature k(σ, p) into areas with the same sectional curvature, and so on. The set of all equi-Gaussian curvature foldings of M into N will be denoted by.

  15. A field survey of metal binding to metallothionein and other cytosolic ligands in liver of eels using an on-line isotope dilution method in combination with size exclusion (SE) high pressure liquid chromatography (HPLC) coupled to Inductively Coupled Plasma time-of-flight Mass Spectrometry (ICP-TOFMS).

    Science.gov (United States)

    Van Campenhout, Karen; Goenaga Infante, Heidi; Goemans, Geert; Belpaire, Claude; Adams, Freddy; Blust, Ronny; Bervoets, Lieven

    2008-05-15

    The effect of metal exposure on the accumulation and cytosolic speciation of metals in livers of wild populations of European eel with special emphasis on metallothioneins (MT) was studied. Four sampling sites in Flanders showing different degrees of heavy metal contamination were selected for this purpose. An on-line isotope dilution method in combination with size exclusion (SE) high pressure liquid chromatography (HPLC) coupled to Inductively Coupled Plasma time-of-flight Mass Spectrometry (ICP-TOFMS) was used to study the cytosolic speciation of the metals. The distribution of the metals Cd, Cu, Ni, Pb and Zn among cytosolic fractions displayed strong differences. The cytosolic concentration of Cd, Ni and Pb increased proportionally with the total liver levels. However, the cytosolic concentrations of Cu and Zn only increased above a certain liver tissue threshold level. Cd, Cu and Zn, but not Pb and Ni, were largely associated with the MT pool in correspondence with the environmental exposure and liver tissue concentrations. Most of the Pb and Ni and a considerable fraction of Cu and Zn, but not Cd, were associated to High Molecular Weight (HMW) fractions. The relative importance of the Cu and Zn in the HMW fraction decreased with increasing contamination levels while the MT pool became progressively more important. The close relationship between the cytosolic metal load and the total MT levels or the metals bound on the MT pool indicates that the metals, rather than other stress factors, are the major factor determining MT induction.

  16. Effect of sediments load on growth folds in thin-skinned fold-and-thrust belt: a numerical approach.

    Science.gov (United States)

    Collignon, Marine; Fernandez, Naiara; May, Dave A.; Kaus, Boris J. P.

    2013-04-01

    Over the past decades, the interaction between surface processes and development of mountain belts has been extensively studied. While syntectonic sedimentation appears to control the external development of the fold-and-thrust belts, erosion strongly influences the evolution of internal regions within mountain belts. The effects of sedimentation on brittle deformation have been thoroughly studied using analogue and numerical models of accretionary wedges, however, most of the numerical studies used a 2D model of deformation and/or a simple formulation for the surface processes, where both sedimentation and erosion are rarely present together. Coupled analogue models of deformation and erosion/sedimentation are challenging, due to material and scaling issues, and often only reproduce two end-member cases (no erosion vs very strong erosion, where all the material is removed), but fail to investigate the transitional cases. In contrast, the influence of sedimentation on ductile deformation has not been examined in detail. Thin-skinned fold and thrust belts are seen as the result of compressional deformation of a sediment pile over a weak layer acting as a décollement level. The resulting surface expression has often been interpreted, based on geometrical criteria in terms of fault bend folds, propagation folds or/and detachment folds. Several analogue studies have demonstrated that fold morphology can be influenced by erosion rates or preferential localization of sedimentation, and additionally, that the fold growth can be stopped by increasing the supply of sediments. Here we aim to numerically investigate the effects of sedimentation on the growth of folds in three dimensions. In order to study the feedback between sedimentation and ductile deformation, we have developed a finite-element based landscape evolution model (both erosion and sedimentation) using PETSc, and coupled it to the 3D mechanical code LaMEM. The landscape evolution model uses a non

  17. Impact ionization processes in the steady state of a driven Mott-insulating layer coupled to metallic leads

    Science.gov (United States)

    Sorantin, Max E.; Dorda, Antonius; Held, Karsten; Arrigoni, Enrico

    2018-03-01

    We study a simple model of photovoltaic energy harvesting across a Mott-insulating gap consisting of a correlated layer connected to two metallic leads held at different chemical potentials. We address, in particular, the issue of impact ionization, whereby a particle photoexcited to the high-energy part of the upper Hubbard band uses its extra energy to produce a second particle-hole excitation. We find a drastic increase of the photocurrent upon entering the frequency regime where impact ionization is possible. At large values of the Mott gap, where impact ionization is energetically not allowed, we observe a suppression of the current and a piling up of charge in the high-energy part of the upper Hubbard band. Our study is based on a Floquet dynamical mean-field theory treatment of the steady state with the so-called auxiliary master equation approach as impurity solver. We verify that an additional approximation, taking the self-energy diagonal in the Floquet indices, is appropriate for the parameter range we are considering.

  18. In-situ probing of coupled atomic restructuring and metallicity of oxide heterointerfaces induced by polar adsorbates

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, S. [Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA; Zhou, H. [X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA; Paudel, T. R. [Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, USA; Irwin, J. [Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA; Podkaminer, J. P. [Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA; Bark, C. W. [Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA; Lee, D. [Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA; Kim, T. H. [Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA; Fong, D. D. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA; Rzchowski, M. S. [Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA; Tsymbal, E. Y. [Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, USA; Eom, C. B. [Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA

    2017-10-02

    Microscopic understanding of the surface-controlled conductivity of the two dimensional electron gas at complex oxide interfaces is crucial for developing functional interfaces. We observe conductivity and structural modification using in-situ synchrotron surface x-ray diffraction as the surface of a model LaAlO3/SrTiO3 (001) heterostructure is changed by polar adsorbates. We find that polar adsorbate-induced interfacial metallicity reduces polar distortions in the LaAlO3 layer. First-principles density functional theory calculations show that surface dipoles introduced by polar adsorbates lead to additional charge transfer and the reduction of polar displacements in the LaAlO3 layer, consistent with the experimental observations. Our study supports that internal structural deformations controlling functionalities can be driven without the application of direct electrical or thermal bias and offers a route to tuning interfacial properties. These results also highlight the important role of in-situ x-ray scattering with atomic resolution in capturing and exploring structural distortions and charge density changes caused by external perturbations such as chemical adsorption, redox reaction, and generation and/or annihilation of surface defects.

  19. Protein disulfide-isomerase interacts with a substrate protein at all stages along its folding pathway.

    Directory of Open Access Journals (Sweden)

    Alistair G Irvine

    Full Text Available In contrast to molecular chaperones that couple protein folding to ATP hydrolysis, protein disulfide-isomerase (PDI catalyzes protein folding coupled to formation of disulfide bonds (oxidative folding. However, we do not know how PDI distinguishes folded, partly-folded and unfolded protein substrates. As a model intermediate in an oxidative folding pathway, we prepared a two-disulfide mutant of basic pancreatic trypsin inhibitor (BPTI and showed by NMR that it is partly-folded and highly dynamic. NMR studies show that it binds to PDI at the same site that binds peptide ligands, with rapid binding and dissociation kinetics; surface plasmon resonance shows its interaction with PDI has a Kd of ca. 10(-5 M. For comparison, we characterized the interactions of PDI with native BPTI and fully-unfolded BPTI. Interestingly, PDI does bind native BPTI, but binding is quantitatively weaker than with partly-folded and unfolded BPTI. Hence PDI recognizes and binds substrates via permanently or transiently unfolded regions. This is the first study of PDI's interaction with a partly-folded protein, and the first to analyze this folding catalyst's changing interactions with substrates along an oxidative folding pathway. We have identified key features that make PDI an effective catalyst of oxidative protein folding - differential affinity, rapid ligand exchange and conformational flexibility.

  20. Restricted accessed nanoparticles for direct magnetic solid phase extraction of trace metal ions from human fluids followed by inductively coupled plasma mass spectrometry detection.

    Science.gov (United States)

    Yan, Ping; He, Man; Chen, Beibei; Hu, Bin

    2015-06-21

    Herein, restricted accessed magnetic nanoparticles were synthesized by self-assembly of a non-ionic surfactant (Tween-20) onto the 4-(2-pyridylazo)resorcinol (PAR) functionalized magnetic nanoparticles (MNPs). A series of analytical techniques were employed for the characterization of the as-prepared restricted accessed Fe3O4@SiO2@PAR, and it was found that the as-prepared restricted accessed Fe3O4@SiO2@PAR nanoparticles have a porous structure with a BET surface area of around 99.4 m(2) g(-1), an average pore size of about 6.14 nm and a pore volume of 0.47 cm(3) g(-1). Besides, the prepared restricted accessed Fe3O4@SiO2@PAR showed good size exclusion properties toward proteins, providing application potential for the direct analysis of biological samples. Based on this, a novel method of restricted accessed magnetic solid phase extraction (MSPE) combined with inductively coupled plasma-mass spectrometry (ICP-MS) was developed for the direct determination of trace metal ions in human fluids. The parameters affecting the extraction of the target metals by MSPE were studied and the optimized conditions were established. Under the optimum conditions, the adsorption capacity of Cr(III), Cd(II), La(III), Nd(III) and Pb(II) on the as-prepared restricted accessed Fe3O4@SiO2@PAR was 62.9, 56.6, 33.7, 36.9 and 43.3 mg g(-1), respectively. With an enrichment factor of 30, the limits of detection for Cr(III), Cd(II), La(III), Nd(III) and Pb(II) were as low as 11.9, 0.8, 0.7, 1.6 and 4.1 ng L(-1), and the relative standard deviations were 7.6, 8.7, 8.4, 8.1 and 5.0 (C(Cr, Pb) = 0.05 μg L(-1), C(Cd, La) = 0.005 μg L(-1), C(Nd) = 0.01 μg L(-1), n = 7), respectively. The developed method was successfully applied for the direct analysis of free metal ions in human urine and serum samples, and has the advantages of good anti-interference ability, high sensitivity and exhibits great application potential in the direct analysis of trace metals in biological fluids.

  1. Synovial folds in equine articular process joints

    DEFF Research Database (Denmark)

    Thomsen, Line Nymann; Berg, Lise Charlotte; Markussen, Bo

    2013-01-01

    Cervical synovial folds have been suggested as a potential cause of neck pain in humans. Little is known about the extent and characteristics of cervical synovial folds in horses.......Cervical synovial folds have been suggested as a potential cause of neck pain in humans. Little is known about the extent and characteristics of cervical synovial folds in horses....

  2. Separation of metallic cations by means of coupled filtration on a ceramic membrane. Use of a complexing heteropolyanion

    International Nuclear Information System (INIS)

    Brun, Stephane

    1999-01-01

    In the field of the high level nuclear waste reprocessing, the Nuclear French Agency is currently carrying out studies on several processes (including the SESAME process) which aim at separating radioactive elements in order to dispose them specifically or to transmute them. One of these processes concerns the selective extraction of americium at an upper oxidation state than Ill. This work deals with the separation of Am(IV) from Ln(Ill) by means of complexation-coupled tangential filtration on alumina-titanium ceramic membranes. The chosen selective complexing agent is a lacunar heteropolyanion from the tungstophosphate family α 2 P 2 W 17 O 61 10- , which synthesis and various properties in solution have been studied. The polyanion stability in 0.5 M nitric solution strongly depends on the quality of the synthesised product. Two analytical techniques were developed to check the quality of the synthesised sets: 31 P NMR and arsenazo-lanthanum complexometric titration. The separation studies on the cerium (IV)-neodymium (Ill) system were carried out to simulate americium(IV)/lanthanides(Ill) system. For the two alumina-titanium membranes studied (ultrafiltration and nano-filtration), the solvent flow can be described through a capillary mechanism which is characteristic of porous membranes. The ion transfer through the membranes, mainly governed by electrostatic interactions, strongly depends on the ionic strength at the membrane-solution interface. The best separation results, using nano-filtration, still remain below the expected performances, with a Ce(IV)/Nd(Ill) separation factor of 35 on a single stage in 0,5 M nitric medium. (author) [fr

  3. Single Particle-Inductively Coupled Plasma Mass Spectroscopy Analysis of Metallic Nanoparticles in Environmental Samples with Large Dissolved Analyte Fractions.

    Science.gov (United States)

    Schwertfeger, D M; Velicogna, Jessica R; Jesmer, Alexander H; Scroggins, Richard P; Princz, Juliska I

    2016-10-18

    There is an increasing interest to use single particle-inductively coupled plasma mass spectroscopy (SP-ICPMS) to help quantify exposure to engineered nanoparticles, and their transformation products, released into the environment. Hindering the use of this analytical technique for environmental samples is the presence of high levels of dissolved analyte which impedes resolution of the particle signal from the dissolved. While sample dilution is often necessary to achieve the low analyte concentrations necessary for SP-ICPMS analysis, and to reduce the occurrence of matrix effects on the analyte signal, it is used here to also reduce the dissolved signal relative to the particulate, while maintaining a matrix chemistry that promotes particle stability. We propose a simple, systematic dilution series approach where by the first dilution is used to quantify the dissolved analyte, the second is used to optimize the particle signal, and the third is used as an analytical quality control. Using simple suspensions of well characterized Au and Ag nanoparticles spiked with the dissolved analyte form, as well as suspensions of complex environmental media (i.e., extracts from soils previously contaminated with engineered silver nanoparticles), we show how this dilution series technique improves resolution of the particle signal which in turn improves the accuracy of particle counts, quantification of particulate mass and determination of particle size. The technique proposed here is meant to offer a systematic and reproducible approach to the SP-ICPMS analysis of environmental samples and improve the quality and consistency of data generated from this relatively new analytical tool.

  4. Effects of various heavy metal nanoparticles on Enterococcus hirae and Escherichia coli growth and proton-coupled membrane transport.

    Science.gov (United States)

    Vardanyan, Zaruhi; Gevorkyan, Vladimir; Ananyan, Michail; Vardapetyan, Hrachik; Trchounian, Armen

    2015-10-16

    Due to bacterial resistance to antibiotics there is a need for new antimicrobial agents. In this respect nanoparticles can be used as they have expressed antibacterial activity simultaneously being more reactive compared to their bulk material. The action of zinc (II), titanium (IV), copper (II) and (I) oxides thin films with nanostructured surface and silver nanoscale particles on Enterococcus hirae and Escherichia coli growth and membrane activity was studied by using microbiological, potentiometric and spectrophotometric methods. It was revealed that sapphire base plates with deposited ZnO, TiO2, CuO and Cu2O nanoparticles had no effects neither on E. hirae nor E. coli growth both on agar plates and in liquid medium. Concentrated Ag nanoparticles colloid solution markedly affected bacterial growth which was expressed by changing growth properties. E. hirae was able to grow only at <1:200 dilutions of Ag nanoparticles while E. coli grew even at 1:10 dilution. At the same time Ag nanoparticles directly affected membranes, as the FOF1-ATPase activity and H(+)-coupled transport was changed either (E. coli were less susceptible to nanoparticles compared to E. hirae). Ag nanoparticles increased H(+) and K(+) transport even in the presence of N,N'-dicyclohexylcarbodiimide (DCCD), inhibitor of FOF1. The stoichiometry of DCCD-inhibited ion fluxes was disturbed. These results point out to distinguishing antibacterial effects of Ag nanoparticles on different bacteria; the difference between effects can be explained by peculiarities in bacterial membrane structure and properties. H(+)-K(+)-exchange disturbance by Ag nanoparticles might be involved in antibacterial effects on E. hirae. The role of FOF1 in antibacterial action of Ag nanoparticles was shown using atpD mutant lacked β subunit in F1.

  5. Influence of metal deposition on exciton-surface plasmon polariton coupling in GaAs/AlAs/GaAs core-shell nanowires studied with time-resolved cathodoluminescence.

    Science.gov (United States)

    Estrin, Yevgeni; Rich, Daniel H; Kretinin, Andrey V; Shtrikman, Hadas

    2013-04-10

    The coupling of excitons to surface plasmon polaritons (SPPs) in Au- and Al-coated GaAs/AlAs/GaAs core-shell nanowires, possessing diameters of ~100 nm, was probed using time-resolved cathodoluminescence (CL). Excitons were generated in the metal coated nanowires by injecting a pulsed high-energy electron beam through the thin metal films. The Purcell enhancement factor (FP) was obtained by direct measurement of changes in the temperature-dependent radiative lifetime caused by the nanowire exciton-SPP coupling and compared with a model that takes into account the dependence of FP on the distance from the metal film and the thickness of the film covering the GaAs nanowires.

  6. Folding wings like a cockroach: a review of transverse wing folding ensign wasps (Hymenoptera: Evaniidae: Afrevania and Trissevania.

    Directory of Open Access Journals (Sweden)

    István Mikó

    Full Text Available We revise two relatively rare ensign wasp genera, whose species are restricted to Sub-Saharan Africa: Afrevania and Trissevania. Afrevania longipetiolata sp. nov., Trissevania heatherae sp. nov., T. hugoi sp. nov., T. mrimaensis sp. nov. and T. slideri sp. nov. are described, males and females of T. anemotis and Afrevania leroyi are redescribed, and an identification key for Trissevaniini is provided. We argue that Trissevania mrimaensis sp. nov. and T. heatherae sp. nov. populations are vulnerable, given their limited distributions and threats from mining activities in Kenya. We hypothesize that these taxa together comprise a monophyletic lineage, Trissevaniini, tr. nov., the members of which share the ability to fold their fore wings along two intersecting fold lines. Although wing folding of this type has been described for the hind wing of some insects four-plane wing folding of the fore wing has never been documented. The wing folding mechanism and the pattern of wing folds of Trissevaniini is shared only with some cockroach species (Blattodea. It is an interesting coincidence that all evaniids are predators of cockroach eggs. The major wing fold lines of Trissevaniini likely are not homologous to any known longitudinal anatomical structures on the wings of other Evaniidae. Members of the new tribe share the presence of a coupling mechanism between the fore wing and the mesosoma that is composed of a setal patch on the mesosoma and the retinaculum of the fore wing. While the setal patch is an evolutionary novelty, the retinaculum, which originally evolved to facilitate fore and hind wing coupling in Hymenoptera, exemplifies morphological exaptation. We also refine and clarify the Semantic Phenotype approach used in previous taxonomic revisions and explore the consequences of merging new with existing data. The way that semantic statements are formulated can evolve in parallel, alongside improvements to the ontologies themselves.

  7. Trace metal analysis by laser ablation-inductively coupled plasmamass spectrometry and x-ray K-edge densitometry of forensic samples

    Energy Technology Data Exchange (ETDEWEB)

    Berry, Jonna Elizabeth [Iowa State Univ., Ames, IA (United States)

    2016-10-25

    This dissertation describes a variety of studies on the determination of trace elements in samples with forensic importance. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) was used to determine the trace element composition of numerous lipstick samples. Lipstick samples were determined to be homogeneous. Most lipstick samples of similar colors were readily distinguishable at a 95% confidence interval based on trace element composition. Numerous strands of a multi-strand speaker cable were analyzed by LA-ICP-MS. The strands in this study are spatially heterogeneous in trace element composition. In actual forensic applications, the possibility of spatial heterogeneity must be considered, especially in cases where only small samples (e.g., copper wire fragments after an explosion) are available. The effects of many unpredictable variables, such as weather, temperature, and human activity, on the retention of gunshot residue (GSR) around projectile wounds were assessed with LAICP- MS. Skin samples around gunshot and stab wounds and larvae feeding in and around the wounds on decomposing pig carcasses were analyzed for elements consistent with GSR (Sb, Pb, Ba, and Cu). These elements were detected at higher levels in skin and larvae samples around the gunshot wounds compared to the stab wounds for an extended period of time throughout decomposition in both a winter and summer study. After decomposition, radiographic images of the pig bones containing possible damage from bullets revealed metallic particles embedded within a number of bones. Metallic particles within the bones were analyzed with x-ray, K-edge densitometry and determined to contain lead, indicating that bullet residue can be retained throughout decomposition and detected within bones containing projectile trauma.

  8. The creation of strongly coupled plasmas using an intense heavy ion beam: low-entropy compression of hydrogen and the problem of hydrogen metallization

    Energy Technology Data Exchange (ETDEWEB)

    Tahir, N A [Institut fuer Theoretische Physik, Universitaet Frankfurt, Postfach 11 19 32, 60054 Frankfurt (Germany); Piriz, A R [ETSI Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real (Spain); Shutov, A [Institute for Problems in Chemical Physics Research, Chernogolovka, Russia (Russian Federation); Varentsov, D [Institut fuer Kernphysik, Technische Universitaet Darmstadt, Schlossgarten Str. 9, 64289 Darmstadt (Germany); Udrea, S [Institut fuer Kernphysik, Technische Universitaet Darmstadt, Schlossgarten Str. 9, 64289 Darmstadt (Germany); Hoffmann, D H H [Institut fuer Kernphysik, Technische Universitaet Darmstadt, Schlossgarten Str. 9, 64289 Darmstadt (Germany); Juranek, H [Fachbereich Physik, Universitaet Rostock, 18051 Rostock (Germany); Redmer, R [Fachbereich Physik, Universitaet Rostock, 18051 Rostock (Germany); Portugues, R F [ETSI Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real (Spain); Lomonosov, I [Institute for Problems in Chemical Physics Research, Chernogolovka, Russia (Russian Federation); Fortov, V E [Institute for Problems in Chemical Physics Research, Chernogolovka, Russia (Russian Federation)

    2003-06-06

    Intense heavy ion beams deposit energy very efficiently over extended volumes of solid density targets, thereby creating large samples of strongly coupled plasmas. Intense beams of energetic heavy ions are therefore an ideal tool to research this interesting field. It is also possible to design experiments using special beam-target geometries to achieve low-entropy compression of samples of matter. This type of experiments is of particular interest for studying the problem of hydrogen metallization. In this paper we present a design study of such a proposed experiment that will be carried out at the future heavy ion synchrotron facility SIS100, at the Gesellschaft fuer Schwerionenforschung, Darmstadt. This study has been done using a two-dimensional hydrodynamic computer code. The target consists of a solid hydrogen cylinder that is enclosed in a thick shell of lead whose one face is irradiated with an ion beam which has an annular (ring shaped) focal spot. The beam intensity and other parameters are considered to be the same as expected at the future SIS100 facility. The simulations show that due to multiple shock reflection between the cylinder axis and the lead-hydrogen boundary, one can achieve up to 20 times solid density in hydrogen while keeping the temperature as low as a few thousand K. The corresponding pressure is of the order of 10 Mbar. These values of the physical parameters lie within the range of theoretically predicted values for hydrogen metallization. We have also carried out a parameter study of this problem by varying the target and beam parameters over a wide range. It has been found that the results are very insensitive to such changes in the input parameters.

  9. Pair natural orbital and canonical coupled cluster reaction enthalpies involving light to heavy alkali and alkaline earth metals: the importance of sub-valence correlation

    KAUST Repository

    Minenkov, Yury

    2017-03-07

    In this work, we tested canonical and domain based pair natural orbital coupled cluster methods (CCSD(T) and DLPNO-CCSD(T), respectively) for a set of 32 ligand exchange and association/dissociation reaction enthalpies involving ionic complexes of Li, Be, Na, Mg, Ca, Sr, Ba and Pb(ii). Two strategies were investigated: in the former, only valence electrons were included in the correlation treatment, giving rise to the computationally very efficient FC (frozen core) approach; in the latter, all non-ECP electrons were included in the correlation treatment, giving rise to the AE (all electron) approach. Apart from reactions involving Li and Be, the FC approach resulted in non-homogeneous performance. The FC approach leads to very small errors (<2 kcal mol-1) for some reactions of Na, Mg, Ca, Sr, Ba and Pb, while for a few reactions of Ca and Ba deviations up to 40 kcal mol-1 have been obtained. Large errors are both due to artificial mixing of the core (sub-valence) orbitals of metals and the valence orbitals of oxygen and halogens in the molecular orbitals treated as core, and due to neglecting core-core and core-valence correlation effects. These large errors are reduced to a few kcal mol-1 if the AE approach is used or the sub-valence orbitals of metals are included in the correlation treatment. On the technical side, the CCSD(T) and DLPNO-CCSD(T) results differ by a fraction of kcal mol-1, indicating the latter method as the perfect choice when the CPU efficiency is essential. For completely black-box applications, as requested in catalysis or thermochemical calculations, we recommend the DLPNO-CCSD(T) method with all electrons that are not covered by effective core potentials included in the correlation treatment and correlation-consistent polarized core valence basis sets of cc-pwCVQZ(-PP) quality.

  10. Protein folding and wring resonances

    DEFF Research Database (Denmark)

    Bohr, Jakob; Bohr, Henrik; Brunak, Søren

    1997-01-01

    The polypeptide chain of a protein is shown to obey topological contraints which enable long range excitations in the form of wring modes of the protein backbone. Wring modes of proteins of specific lengths can therefore resonate with molecular modes present in the cell. It is suggested that prot......The polypeptide chain of a protein is shown to obey topological contraints which enable long range excitations in the form of wring modes of the protein backbone. Wring modes of proteins of specific lengths can therefore resonate with molecular modes present in the cell. It is suggested...... that protein folding takes place when the amplitude of a wring excitation becomes so large that it is energetically favorable to bend the protein backbone. The condition under which such structural transformations can occur is found, and it is shown that both cold and hot denaturation (the unfolding...

  11. Bodies Folded in Migrant Crypts

    DEFF Research Database (Denmark)

    Galis, Vasilis; Tzokas, Spyros; Tympas, Aristotle

    2016-01-01

    , and to performing mobility in general. Dis/ability and migration have not been associated in the literature. We adopt an analytical symmetry between humans and non-humans, in this case between bodies and crypts. By suggesting an infected, ambivalent, and hybrid approach to the human subject, the body......This article considers media narratives that suggest that hiding in trucks, buses, and other vehicles to cross borders has, in fact, been a common practice in the context of migration to, and within, Europe. We aim to problematize how the tension between the materiality of bordering practices...... and human migrants generates a dis/abled subject. In this context, dis/ability may be a cause or consequence of migration, both in physical/material (the folding of bodies in the crypt) and cultural/semiotic terms, and may become a barrier to accessing protection, to entering and/or crossing a country...

  12. Fluoroangiographic picture of chorioretinal folds

    International Nuclear Information System (INIS)

    Kalvodova, B.; Karel, I.

    1988-01-01

    Fluoroangiographic pictures of chorioretinal folds (CRF) were analyzed in 13 eyes of 12 patients. The orbital origin of CRF was present in 8 eyes (orbital tumors in 7 eyes and thyroid ophthalmopathy in one eye), the intraocular origin in 5 eyes (hypotonic postoperative syndrome caused by the detachment of the choroid in 3 eyes, Irwine-Gass syndrome in 2 eyes, scleral bucle used for retinal detachment repair in one eye). The fluoroangiographic findings of CRF were determined by changes in the pigmented epithelium and choroid of a different degree, which modified the clinical picture of the basic disease. Fluorescein angiography is a very useful method for the differentiation of retinal and choroid detachments but with a limited possibility to determine the etiological factor of the disease. (author). 6 figs., 2 tabs., 32 refs

  13. Automated magnetic sorbent extraction based on octadecylsilane functionalized maghemite magnetic particles in a sequential injection system coupled with electrothermal atomic absorption spectrometry for metal determination.

    Science.gov (United States)

    Giakisikli, Georgia; Anthemidis, Aristidis N

    2013-06-15

    A new automatic sequential injection (SI) system for on-line magnetic sorbent extraction coupled with electrothermal atomic absorption spectrometry (ETAAS) has been successfully developed for metal determination. In this work, we reported effective on-line immobilization of magnetic silica particles into a microcolumn by the external force of two strong neodymium iron boron (NdFeB) magnets across it, avoiding the use of frits. Octadecylsilane functionalized maghemite magnetic particles were used as sorbent material. The potentials of the system were demonstrated for trace cadmium determination in water samples. The method was based on the on-line complex formation with diethyldithiocarbamate (DDTC), retention of Cd-DDTC on the surface of the MPs and elution with isobutyl methyl ketone (IBMK). The formation mechanism of the magnetic solid phase packed column and all critical parameters (chemical, flow, graphite furnace) influencing the performance of the system were optimized and offered good analytical characteristics. For 5 mL sample volume, a detection limit of 3 ng L(-1), a relative standard deviation of 3.9% at 50 ng L(-1) level (n=11) and a linear range of 9-350 ng L(-1) were obtained. The column remained stable for more than 600 cycles keeping the cost down in routine analysis. The proposed method was evaluated by analyzing certified reference materials and natural waters. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Coupling of Acoustic Cavitation with Dem-Based Particle Solvers for Modeling De-agglomeration of Particle Clusters in Liquid Metals

    Science.gov (United States)

    Manoylov, Anton; Lebon, Bruno; Djambazov, Georgi; Pericleous, Koulis

    2017-11-01

    The aerospace and automotive industries are seeking advanced materials with low weight yet high strength and durability. Aluminum and magnesium-based metal matrix composites with ceramic micro- and nano-reinforcements promise the desirable properties. However, larger surface-area-to-volume ratio in micro- and especially nanoparticles gives rise to van der Waals and adhesion forces that cause the particles to agglomerate in clusters. Such clusters lead to adverse effects on final properties, no longer acting as dislocation anchors but instead becoming defects. Also, agglomeration causes the particle distribution to become uneven, leading to inconsistent properties. To break up clusters, ultrasonic processing may be used via an immersed sonotrode, or alternatively via electromagnetic vibration. This paper combines a fundamental study of acoustic cavitation in liquid aluminum with a study of the interaction forces causing particles to agglomerate, as well as mechanisms of cluster breakup. A non-linear acoustic cavitation model utilizing pressure waves produced by an immersed horn is presented, and then applied to cavitation in liquid aluminum. Physical quantities related to fluid flow and quantities specific to the cavitation solver are passed to a discrete element method particles model. The coupled system is then used for a detailed study of clusters' breakup by cavitation.

  15. Analysis of six heavy metals in Ortho mineral trioxide aggregate and ProRoot mineral trioxide aggregate by inductively coupled plasma-optical emission spectrometry.

    Science.gov (United States)

    Kum, Kee-Yeon; Zhu, Qiang; Safavi, Kamran; Gu, Yu; Bae, Kwang-Shik; Chang, Seok Woo

    2013-12-01

    Ortho mineral trioxide aggregate (MTA) is a mineral aggregate newly developed for perforation repair, root end filling and pulp capping. The aim of this study was to investigate the levels of cadmium (Cd), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni) and zinc (Zn) in Ortho MTA and ProRoot MTA. A total of 0.2 g of each MTA was digested using a mixture of hydrochloric and nitric acids and filtered. Six heavy metals in the resulting filtrates were analyzed by inductively coupled plasma-optical emission spectrometry (n = 5). The results were statistically analyzed using the Mann-Whitney U-test. The concentrations of Cd, Cu, Fe, Mn, Ni and Zn in Ortho MTA were 0.10, 7.73, 49.51, 2.58, 0.82 and 10.09 p.p.m., respectively. The concentrations of Cd, Cu, Fe, Mn, Ni and Zn in ProRoot MTA were 0.16, 9.38, 1438.11, 74.51, 18.98 and 4.05 p.p.m., respectively. In conclusion, Ortho MTA had lower levels of Cd, Cu, Fe, Mn and Ni than ProRoot MTA. © 2012 The Authors. Australian Endodontic Journal © 2012 Australian Society of Endodontology.

  16. Semiconductor color-center structure and excitation spectra: Equation-of-motion coupled-cluster description of vacancy and transition-metal defect photoluminescence

    Science.gov (United States)

    Lutz, Jesse J.; Duan, Xiaofeng F.; Burggraf, Larry W.

    2018-03-01

    Valence excitation spectra are computed for deep-center silicon-vacancy defects in 3C, 4H, and 6H silicon carbide (SiC), and comparisons are made with literature photoluminescence measurements. Optimizations of nuclear geometries surrounding the defect centers are performed within a Gaussian basis-set framework using many-body perturbation theory or density functional theory (DFT) methods, with computational expenses minimized by a QM/MM technique called SIMOMM. Vertical excitation energies are subsequently obtained by applying excitation-energy, electron-attached, and ionized equation-of-motion coupled-cluster (EOMCC) methods, where appropriate, as well as time-dependent (TD) DFT, to small models including only a few atoms adjacent to the defect center. We consider the relative quality of various EOMCC and TD-DFT methods for (i) energy-ordering potential ground states differing incrementally in charge and multiplicity, (ii) accurately reproducing experimentally measured photoluminescence peaks, and (iii) energy-ordering defects of different types occurring within a given polytype. The extensibility of this approach to transition-metal defects is also tested by applying it to silicon-substituted chromium defects in SiC and comparing with measurements. It is demonstrated that, when used in conjunction with SIMOMM-optimized geometries, EOMCC-based methods can provide a reliable prediction of the ground-state charge and multiplicity, while also giving a quantitative description of the photoluminescence spectra, accurate to within 0.1 eV of measurement for all cases considered.

  17. The creation of strongly coupled plasmas using an intense heavy ion beam: low-entropy compression of hydrogen and the problem of hydrogen metallization

    CERN Document Server

    Tahir, N A; Shutov, A; Varentsov, D; Udrea, S; Hoffmann, Dieter H H; Juranek, H; Redmer, R; Portugues, R F; Lomonosov, I V; Fortov, V E

    2003-01-01

    Intense heavy ion beams deposit energy very efficiently over extended volumes of solid density targets, thereby creating large samples of strongly coupled plasmas. Intense beams of energetic heavy ions are therefore an ideal tool to research this interesting field. It is also possible to design experiments using special beam-target geometries to achieve low-entropy compression of samples of matter. This type of experiments is of particular interest for studying the problem of hydrogen metallization. In this paper we present a design study of such a proposed experiment that will be carried out at the future heavy ion synchrotron facility SIS100, at the Gesellschaft fuer Schwerionenforschung, Darmstadt. This study has been done using a two-dimensional hydrodynamic computer code. The target consists of a solid hydrogen cylinder that is enclosed in a thick shell of lead whose one face is irradiated with an ion beam which has an annular (ring shaped) focal spot. The beam intensity and other parameters are consider...

  18. The surgical anatomy of the nasolabial fold.

    Science.gov (United States)

    Pogrel, M A; Shariati, S; Schmidt, B; Faal, Z H; Regezi, J

    1998-10-01

    The purpose of this cadaver dissection study was to investigate the anatomy of the nasolabial fold with a view to explaining the problems of surgical softening or elimination of the fold. Ten formalin-fixed cadavers and 6 fresh-frozen cadavers were used for this study. In 12 cadavers (8 formalin-fixed, 4 fresh-frozen), the nasolabial fold was sectioned at right angles to the fold for histologic examination, and in 4 cadavers (2 formalin-fixed, 2 fresh-frozen) the epithelium was dissected off the fold to allow for more detailed gross examination of the underlying musculature. The fold was clearly identified on 14 of the cadavers but was indistinct on 2 on gross examination. Beneath the fold were 2 muscle bundles. The more superficial muscle runs parallel to the fold whereas a deeper muscle runs at right angles to it. The buccal fat pad lies above the fold and appears to be retained by horizontal septae in the fat pad and also by the musculature of the fold. Cadavers showing a poorly defined nasolabial fold had fewer muscle bundles to support the fat and fewer fibrous septae running through the fat. The nasolabial fold is defined by structures that support the buccal fat pad and hold it above the fold. This appears to be a combination of muscle bundles that run both across and parallel to the fold and also by fibrous septae supporting the fat pad. This has implications for the development of surgical procedures to soften or eliminate the fold, which must separate the muscles from the dermis of the fold and allow the fat to descend and soften the fold.

  19. Preparation and self-folding of amphiphilic DNA origami.

    Science.gov (United States)

    Zhou, Chao; Wang, Dianming; Dong, Yuanchen; Xin, Ling; Sun, Yawei; Yang, Zhongqiang; Liu, Dongsheng

    2015-03-01

    Amphiphilic DNA origami is prepared by dressing multiple hydrophobic molecules on a rectangular single layer DNA origami, which is then folded or coupled in sandwich-like structures with two outer DNA origami layer and one inner hydrophobic molecules layer. The preference to form different kinds of structures could be tailored by rational design of DNA origami. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. The parallel universe of RNA folding.

    Science.gov (United States)

    Batey, R T; Doudna, J A

    1998-05-01

    How do large RNA molecules find their active conformations among a universe of possible structures? Two recent studies reveal that RNA folding is a rapid and ordered process, with surprising similarities to protein folding mechanisms.

  1. WW domain folding complexity revealed by infrared spectroscopy.

    Science.gov (United States)

    Davis, Caitlin M; Dyer, R Brian

    2014-09-02

    Although the intrinsic tryptophan fluorescence of proteins offers a convenient probe of protein folding, interpretation of the fluorescence spectrum is often difficult because it is sensitive to both global and local changes. Infrared (IR) spectroscopy offers a complementary measure of structural changes involved in protein folding, because it probes changes in the secondary structure of the protein backbone. Here we demonstrate the advantages of using multiple probes, infrared and fluorescence spectroscopy, to study the folding of the FBP28 WW domain. Laser-induced temperature jumps coupled with fluorescence or infrared spectroscopy have been used to probe changes in the peptide backbone on the submillisecond time scale. The relaxation dynamics of the β-sheets and β-turn were measured independently by probing the corresponding IR bands assigned in the amide I region. Using these wavelength-dependent measurements, we observe three kinetics phases, with the fastest process corresponding to the relaxation kinetics of the turns. In contrast, fluorescence measurements of the wild-type WW domain and tryptophan mutants exhibit single-exponential kinetics with a lifetime that corresponds to the slowest phase observed by infrared spectroscopy. Mutant sequences provide evidence of an intermediate dry molten globule state. The slowest step in the folding of this WW domain is the tight packing of the side chains in the transition from the dry molten globule intermediate to the native structure. This study demonstrates that using multiple complementary probes enhances the interpretation of protein folding dynamics.

  2. Anatomy and Histology of an Epicanthal Fold.

    Science.gov (United States)

    Park, Jae Woo; Hwang, Kun

    2016-06-01

    The aim of this study is to elucidate the precise anatomical and histological detail of the epicanthal fold.Thirty-two hemifaces of 16 Korean adult cadavers were used in this study (30 hemifaces with an epicanthal fold, 2 without an epicanthal fold). In 2 patients who had an epicanthoplasty, the epicanthal folds were sampled.In a dissection, the periorbital skin and subcutaneous tissues were removed and the epicanthal fold was observed in relation to each part of the orbicularis oculi muscle. Specimens including the epicanthal fold were embeddedin in paraffin, sectioned at 10 um, and stained with Hematoxylin-Eosin. The horizontal section in the level of the paplebral fissure was made and the prepared slides were observed under a light microscope.In the specimens without an epicanthal fold, no connection between the upper preseptal muscle and the lower preseptal muscle was found. In the specimens with an epicanthal fold, a connection of the upper preseptal muscle to the lower preseptal muscle was observed. It was present in all 15 hemifaces (100%). There was no connection between the pretarsal muscles. In a horizontal section, the epicanthal fold was composed of 3 compartments: an outer skin lining, a core structure, and an innerskin lining. The core structure was mainly composed of muscular fibers and fibrotic tissue and they were intermingled.Surgeons should be aware of the anatomical details of an epicanthal fold. In removing or reconstructing an epicanthal fold, the fibromuscular core band should also be removed or reconstructed.

  3. Feasibility of asymmetric flow field-flow fractionation coupled to ICP-MS for the characterization of wear metal particles and metalloproteins in biofluids from hip replacement patients

    DEFF Research Database (Denmark)

    Löschner, Katrin; Harrington, Chris F.; Kearney, Jacque-Lucca

    2015-01-01

    Hip replacements are used to improve the quality of life of people with orthopaedic conditions, but the use of metal-on-metal (MoM) arthroplasty has led to poor outcomes for some patients. These problems are related to the generation of micro- to nanosized metal wear particles containing Cr, Co o...

  4. Physical interaction and functional coupling between ACDP4 and the intracellular ion chaperone COX11, an implication of the role of ACDP4 in essential metal ion transport and homeostasis

    Directory of Open Access Journals (Sweden)

    Gu Jianguo

    2005-04-01

    Full Text Available Abstract Divalent metal ions such as copper, manganese, and cobalt are essential for cell development, differentiation, function and survival. These essential metal ions are delivered into intracellular domains as cofactors for enzymes involved in neuropeptide and neurotransmitter synthesis, superoxide metabolism, and other biological functions in a target specific fashion. Altering the homeostasis of these essential metal ions is known to connect to a number of human diseases including Alzheimer disease, amyotrophic lateral sclerosis, and pain. It remains unclear how these essential metal ions are delivered to intracellular targets in mammalian cells. Here we report that rat spinal cord dorsal horn neurons express ACDP4, a member of Ancient Conserved Domain Protein family. By screening a pretransformed human fetal brain cDNA library in a yeast two-hybrid system, we have identified that ACDP4 specifically interacts with COX11, an intracellular metal ion chaperone. Ectopic expression of ACDP4 in HEK293 cells resulted in enhanced toxicity to metal ions including copper, manganese, and cobalt. The metal ion toxicity became more pronounced when ACDP4 and COX11 were co-expressed ectopically in HEK293 cells, suggesting a functional coupling between them. Our results indicate a role of ACDP4 in metal ion homeostasis and toxicity. This is the first report revealing a functional aspect of this ancient conserved domain protein family. We propose that ACDP is a family of transporter protein or chaperone proteins for delivering essential metal ions in different mammalian tissues. The expression of ACDP4 on spinal cord dorsal horn neurons may have implications in sensory neuron functions under physiological and pathological conditions.

  5. Viscoelastic properties of the false vocal fold

    Science.gov (United States)

    Chan, Roger W.

    2004-05-01

    The biomechanical properties of vocal fold tissues have been the focus of many previous studies, as vocal fold viscoelasticity critically dictates the acoustics and biomechanics of phonation. However, not much is known about the viscoelastic response of the ventricular fold or false vocal fold. It has been shown both clinically and in computer simulations that the false vocal fold may contribute significantly to the aerodynamics and sound generation processes of human voice production, with or without flow-induced oscillation of the false fold. To better understand the potential role of the false fold in phonation, this paper reports some preliminary measurements on the linear and nonlinear viscoelastic behavior of false vocal fold tissues. Linear viscoelastic shear properties of human false fold tissue samples were measured by a high-frequency controlled-strain rheometer as a function of frequency, and passive uniaxial tensile stress-strain response of the tissue samples was measured by a muscle lever system as a function of strain and loading rate. Elastic moduli (Young's modulus and shear modulus) of the false fold tissues were calculated from the measured data. [Work supported by NIH.

  6. Unified understanding of folding and binding mechanisms of globular and intrinsically disordered proteins.

    Science.gov (United States)

    Arai, Munehito

    2018-01-06

    Extensive experimental and theoretical studies have advanced our understanding of the mechanisms of folding and binding of globular proteins, and coupled folding and binding of intrinsically disordered proteins (IDPs). The forces responsible for conformational changes and binding are common in both proteins; however, these mechanisms have been separately discussed. Here, we attempt to integrate the mechanisms of coupled folding and binding of IDPs, folding of small and multi-subdomain proteins, folding of multimeric proteins, and ligand binding of globular proteins in terms of conformational selection and induced-fit mechanisms as well as the nucleation-condensation mechanism that is intermediate between them. Accumulating evidence has shown that both the rate of conformational change and apparent rate of binding between interacting elements can determine reaction mechanisms. Coupled folding and binding of IDPs occurs mainly by induced-fit because of the slow folding in the free form, while ligand binding of globular proteins occurs mainly by conformational selection because of rapid conformational change. Protein folding can be regarded as the binding of intramolecular segments accompanied by secondary structure formation. Multi-subdomain proteins fold mainly by the induced-fit (hydrophobic collapse) mechanism, as the connection of interacting segments enhances the binding (compaction) rate. Fewer hydrophobic residues in small proteins reduce the intramolecular binding rate, resulting in the nucleation-condensation mechanism. Thus, the folding and binding of globular proteins and IDPs obey the same general principle, suggesting that the coarse-grained, statistical mechanical model of protein folding is promising for a unified theoretical description of all mechanisms.

  7. A comparison of RNA folding measures

    DEFF Research Database (Denmark)

    Freyhult, E.; Gardner, P. P.; Moulton, V.

    2005-01-01

    Background In the last few decades there has been a great deal of discussion concerning whether or not noncoding RNA sequences (ncRNAs) fold in a more well-defined manner than random sequences. In this paper, we investigate several existing measures for how well an RNA sequence folds, and compare...... the behaviour of these measures over a large range of Rfam ncRNA families. Such measures can be useful in, for example, identifying novel ncRNAs, and indicating the presence of alternate RNA foldings. Results Our analysis shows that ncRNAs, but not mRNAs, in general have lower minimal free energy (MFE) than...... random sequences with the same dinucleotide frequency. Moreover, even when the MFE is significant, many ncRNAs appear to not have a unique fold, but rather several alternative folds, at least when folded in silico. Furthermore, we find that the six investigated measures are correlated to varying degrees...

  8. Adaptive Origami for Efficiently Folded Structures

    Science.gov (United States)

    2016-02-01

    AFRL-RQ-WP-TR-2016-0020 ADAPTIVE ORIGAMI FOR EFFICIENTLY FOLDED STRUCTURES James J. Joo and Greg Reich Design and Analysis Branch... ORIGAMI FOR EFFICIENTLY FOLDED STRUCTURES 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR(S) James J...NOTES PA Case Number: 88ABW-2016-0843; Clearance Date: 25 February 2016. 14. ABSTRACT Origami , the art of paper folding, transforms a flat sheet into

  9. Guiding the folding pathway of DNA origami.

    Science.gov (United States)

    Dunn, Katherine E; Dannenberg, Frits; Ouldridge, Thomas E; Kwiatkowska, Marta; Turberfield, Andrew J; Bath, Jonathan

    2015-09-03

    DNA origami is a robust assembly technique that folds a single-stranded DNA template into a target structure by annealing it with hundreds of short 'staple' strands. Its guiding design principle is that the target structure is the single most stable configuration. The folding transition is cooperative and, as in the case of proteins, is governed by information encoded in the polymer sequence. A typical origami folds primarily into the desired shape, but misfolded structures can kinetically trap the system and reduce the yield. Although adjusting assembly conditions or following empirical design rules can improve yield, well-folded origami often need to be separated from misfolded structures. The problem could in principle be avoided if assembly pathway and kinetics were fully understood and then rationally optimized. To this end, here we present a DNA origami system with the unusual property of being able to form a small set of distinguishable and well-folded shapes that represent discrete and approximately degenerate energy minima in a vast folding landscape, thus allowing us to probe the assembly process. The obtained high yield of well-folded origami structures confirms the existence of efficient folding pathways, while the shape distribution provides information about individual trajectories through the folding landscape. We find that, similarly to protein folding, the assembly of DNA origami is highly cooperative; that reversible bond formation is important in recovering from transient misfoldings; and that the early formation of long-range connections can very effectively enforce particular folds. We use these insights to inform the design of the system so as to steer assembly towards desired structures. Expanding the rational design process to include the assembly pathway should thus enable more reproducible synthesis, particularly when targeting more complex structures. We anticipate that this expansion will be essential if DNA origami is to continue its

  10. Merging monads and folds for functional programming

    NARCIS (Netherlands)

    Meijer, E.; Jeuring, J.T.

    1995-01-01

    These notes discuss the simultaneous use of generalised fold operators and monads to structure functional programs. Generalised fold operators structure programs after the decomposition of the value they consume. Monads structure programs after the computation of the value they produce. Our programs

  11. Folded tandem ion accelerator facility at Trombay

    Indian Academy of Sciences (India)

    Keywords. Folded tandem ion accelerator; carbon beam; magnets; electrostatic deflector; quadrupole lenses; foil/gas strippers; Rutherford back scattering. Abstract. The folded tandem ion accelerator (FOTIA) project at BARC has been commissioned. The analysed carbon beams of 40 nA(3+) and 25 nA(4+), at terminal ...

  12. Accelerated molecular dynamics simulations of protein folding.

    Science.gov (United States)

    Miao, Yinglong; Feixas, Ferran; Eun, Changsun; McCammon, J Andrew

    2015-07-30

    Folding of four fast-folding proteins, including chignolin, Trp-cage, villin headpiece and WW domain, was simulated via accelerated molecular dynamics (aMD). In comparison with hundred-of-microsecond timescale conventional molecular dynamics (cMD) simulations performed on the Anton supercomputer, aMD captured complete folding of the four proteins in significantly shorter simulation time. The folded protein conformations were found within 0.2-2.1 Å of the native NMR or X-ray crystal structures. Free energy profiles calculated through improved reweighting of the aMD simulations using cumulant expansion to the second-order are in good agreement with those obtained from cMD simulations. This allows us to identify distinct conformational states (e.g., unfolded and intermediate) other than the native structure and the protein folding energy barriers. Detailed analysis of protein secondary structures and local key residue interactions provided important insights into the protein folding pathways. Furthermore, the selections of force fields and aMD simulation parameters are discussed in detail. Our work shows usefulness and accuracy of aMD in studying protein folding, providing basic references in using aMD in future protein-folding studies. © 2015 Wiley Periodicals, Inc.

  13. THE ALPHA/BETA-HYDROLASE FOLD

    NARCIS (Netherlands)

    OLLIS, DL; CHEAH, E; CYGLER, M; FROLOW, F; FRANKEN, SM; HAREL, M; REMINGTON, SJ; SILMAN, [No Value; SCHRAG, J; SUSSMAN, JL; VERSCHUEREN, KHG; GOLDMAN, A

    We have identified a new protein fold-the alpha/beta-hydrolase fold-that is common to several hydrolytic enzymes of widely differing phylogenetic origin and catalytic function. The core of each enzyme is similar: an alpha/beta-sheet, not barrel, of eight beta-sheets connected by alpha-helices. These

  14. Graph-representation of oxidative folding pathways

    Directory of Open Access Journals (Sweden)

    Kaján László

    2005-01-01

    Full Text Available Abstract Background The process of oxidative folding combines the formation of native disulfide bond with conformational folding resulting in the native three-dimensional fold. Oxidative folding pathways can be described in terms of disulfide intermediate species (DIS which can also be isolated and characterized. Each DIS corresponds to a family of folding states (conformations that the given DIS can adopt in three dimensions. Results The oxidative folding space can be represented as a network of DIS states interconnected by disulfide interchange reactions that can either create/abolish or rearrange disulfide bridges. We propose a simple 3D representation wherein the states having the same number of disulfide bridges are placed on separate planes. In this representation, the shuffling transitions are within the planes, and the redox edges connect adjacent planes. In a number of experimentally studied cases (bovine pancreatic trypsin inhibitor, insulin-like growth factor and epidermal growth factor, the observed intermediates appear as part of contiguous oxidative folding pathways. Conclusions Such networks can be used to visualize folding pathways in terms of the experimentally observed intermediates. A simple visualization template written for the Tulip package http://www.tulip-software.org/ can be obtained from V.A.

  15. Metal release and metal allergy after total hip replacement with resurfacing versus conventional hybrid prosthesis

    Science.gov (United States)

    Gustafson, Klas; Jakobsen, Stig S; Lorenzen, Nina D; Thyssen, Jacob P; Johansen, Jeanne D; Bonefeld, Charlotte M; Stilling, Maiken; Baad-Hansen, Thomas; Søballe, Kjeld

    2014-01-01

    Background Metal-on-metal (MOM) total hip arthroplasties were reintroduced because of the problems with osteolysis and aseptic loosening related to polyethylene wear of early metal-on-polyethylene (MOP) arthroplasties. The volumetric wear rate has been greatly reduced with MOM arthroplasties; however, because of nano-size wear particles, the absolute number has been greatly increased. Thus, a source of metal ion exposure with the potential to sensitize patients is present. We hypothesized that higher amounts of wear particles result in increased release of metal ions and ultimately lead to an increased incidence of metal allergy. Methods 52 hips in 52 patients (median age 60 (51–64) years, 30 women) were randomized to either a MOM hip resurfacing system (ReCap) or a standard MOP total hip arthoplasty (Mallory Head/Exeter). Spot urine samples were collected preoperatively, postoperatively, after 3 months, and after 1, 2, and 5 years and tested with inductively coupled plasma-sector field mass spectrometry. After 5 years, hypersensitivity to metals was evaluated by patch testing and lymphocyte transformation assay. In addition, the patients answered a questionnaire about hypersensitivity. Results A statistically significant 10- to 20-fold increase in urinary levels of cobalt and chromium was observed throughout the entire follow-up in the MOM group. The prevalence of metal allergy was similar between groups. Interpretation While we observed significantly increased levels of metal ions in the urine during the entire follow-up period, no difference in prevalence of metal allergy was observed in the MOM group. However, the effect of long-term metal exposure remains uncertain. PMID:24930546

  16. Fold and Fit: Space Conserving Shape Editing

    KAUST Repository

    Ibrahim, Mohamed

    2017-09-01

    We present a framework that folds man-made objects in a structure-aware manner for space-conserving storage and transportation. Given a segmented 3D mesh of a man-made object, our framework jointly optimizes for joint locations, the folding order, and folding angles for each part of the model, enabling it to transform into a spatially efficient configuration while keeping its original functionality as intact as possible. That is, if a model is supposed to withstand several forces in its initial state to serve its functionality, our framework places the joints between the parts of the model such that the model can withstand forces with magnitudes that are comparable to the magnitudes applied on the unedited model. Furthermore, if the folded shape is not compact, our framework proposes further segmentation of the model to improve its compactness in its folded state.

  17. Geometric U-folds in four dimensions

    Science.gov (United States)

    Lazaroiu, C. I.; Shahbazi, C. S.

    2018-01-01

    We describe a general construction of geometric U-folds compatible with a non-trivial extension of the global formulation of four-dimensional extended supergravity on a differentiable spin manifold. The topology of geometric U-folds depends on certain flat fiber bundles which encode how supergravity fields are globally glued together. We show that smooth non-trivial U-folds of this type can exist only in theories where both the scalar and space-time manifolds have non-trivial fundamental group and in addition the scalar map of the solution is homotopically non-trivial. Consistency with string theory requires smooth geometric U-folds to be glued using subgroups of the effective discrete U-duality group, implying that the fundamental group of the scalar manifold of such solutions must be a subgroup of the latter. We construct simple examples of geometric U-folds in a generalization of the axion-dilaton model of \

  18. Fan-fold shielded electrical leads

    Science.gov (United States)

    Rohatgi, Rajeev R.; Cowan, Thomas E.

    1996-01-01

    Fan-folded electrical leads made from copper cladded Kapton, for example, with the copper cladding on one side serving as a ground plane and the copper cladding on the other side being etched to form the leads. The Kapton is fan folded with the leads located at the bottom of the fan-folds. Electrical connections are made by partially opening the folds of the fan and soldering, for example, the connections directly to the ground plane and/or the lead. The fan folded arrangement produces a number of advantages, such as electrically shielding the leads from the environment, is totally non-magnetic, and has a very low thermal conductivity, while being easy to fabricate.

  19. Ag-protein plasmonic architectures for surface plasmon-coupled emission enhancements and Fabry-Perot mode-coupled directional fluorescence emission

    Science.gov (United States)

    Badiya, Pradeep Kumar; Patnaik, Sai Gourang; Srinivasan, Venkatesh; Reddy, Narendra; Manohar, Chelli Sai; Vedarajan, Raman; Mastumi, Noriyoshi; Belliraj, Siva Kumar; Ramamurthy, Sai Sathish

    2017-10-01

    We report the use of silver decorated plant proteins as spacer material for augmented surface plasmon-coupled emission (120-fold enhancement) and plasmon-enhanced Raman scattering. We extracted several proteins from different plant sources [Triticum aestivum (TA), Aegle marmelos (AM), Ricinus communis (RC), Jatropha curcas (JC) and Simarouba glauca (SG)] followed by evaluation of their optical properties and simulations to rationalize observed surface plasmon resonance. Since the properties exhibited by protein thin films is currently gaining research interest, we have also carried out simulation studies with Ag-protein biocomposites as spacer materials in metal-dielectric-metal planar microcavity architecture for guided emission of Fabry-Perot mode-coupled fluorescence.

  20. Performance of isolated and folded footings

    Directory of Open Access Journals (Sweden)

    Mahmoud Samir El-kady

    2017-04-01

    Full Text Available Folded foundations have been used as an alternative to the conventional flat shallow foundations, in situations involving heavy loads or weak soils. They can be geometrically shaped in many forms especially for isolated footings. The purpose of this paper is introducing an alternative foundation shape that reduces the cost of foundations by reducing the amount of reinforcing steel by minimizing or even eliminating the tension zones in the folded isolated footings. Also, achieving lower soil stresses through changing the isolated footing shape will consequently reduce the expected settlements and the footing stresses. Experimental and numerical studies are performed on five (5 quarter scale footings of which one (1 footing of flat shape is tested as a reference sample and four (4 footings are of folded shape by folding angles of 10°, 20°, 30°, and 40° with the horizontal. Results showed that the folded isolated footings achieve economic design by decreasing the quantities of reinforcement. It also induced less soil settlements, and stresses. In addition, the tensile stresses in the reinforced concrete footing body are also less in folded isolated footings than the flat one. Results show that the folded isolated footing have a better load carrying capacity when compared with the conventional slab/flat footing of similar cross sectional area for both cases of experimental and numerical analysis.

  1. Mapping the Universe of RNA Tetraloop Folds.

    Science.gov (United States)

    Bottaro, Sandro; Lindorff-Larsen, Kresten

    2017-07-25

    We report a map of RNA tetraloop conformations constructed by calculating pairwise distances among all experimentally determined four-nucleotide hairpin loops. Tetraloops with similar structures are clustered together and, as expected, the two largest clusters are the canonical GNRA and UNCG folds. We identify clusters corresponding to known tetraloop folds such as GGUG, RNYA, AGNN, and CUUG. These clusters are represented in a simple two-dimensional projection that recapitulates the relationship among the different folds. The cluster analysis also identifies 20 novel tetraloop folds that are peculiar to specific positions in ribosomal RNAs and that are stabilized by tertiary interactions. In our RNA tetraloop database we find a significant number of non-GNRA and non-UNCG sequences adopting the canonical GNRA and UNCG folds. Conversely, we find a significant number of GNRA and UNCG sequences adopting non-GNRA and non-UNCG folds. Our analysis demonstrates that there is not a simple one-to-one, but rather a many-to-many mapping between tetraloop sequence and tetraloop fold. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  2. Coarsely resolved topography along protein folding pathways

    Science.gov (United States)

    Fernández, Ariel; Kostov, Konstantin S.; Berry, R. Stephen

    2000-03-01

    The kinetic data from the coarse representation of polypeptide torsional dynamics described in the preceding paper [Fernandez and Berry, J. Chem. Phys. 112, 5212 (2000), preceding paper] is inverted by using detailed balance to obtain a topographic description of the potential-energy surface (PES) along the dominant folding pathway of the bovine pancreatic trypsin inhibitor (BPTI). The topography is represented as a sequence of minima and effective saddle points. The dominant folding pathway displays an overall monotonic decrease in energy with a large number of staircaselike steps, a clear signature of a good structure-seeker. The diversity and availability of alternative folding pathways is analyzed in terms of the Shannon entropy σ(t) associated with the time-dependent probability distribution over the kinetic ensemble of contact patterns. Several stages in the folding process are evident. Initially misfolded states form and dismantle revealing no definite pattern in the topography and exhibiting high Shannon entropy. Passage down a sequence of staircase steps then leads to the formation of a nativelike intermediate, for which σ(t) is much lower and fairly constant. Finally, the structure of the intermediate is refined to produce the native state of BPTI. We also examine how different levels of tolerance to mismatches of side chain contacts influence the folding kinetics, the topography of the dominant folding pathway, and the Shannon entropy. This analysis yields upper and lower bounds of the frustration tolerance required for the expeditious and robust folding of BPTI.

  3. Protein-folding location can regulate manganese-binding versus copper- or zinc-binding.

    Science.gov (United States)

    Tottey, Steve; Waldron, Kevin J; Firbank, Susan J; Reale, Brian; Bessant, Conrad; Sato, Katsuko; Cheek, Timothy R; Gray, Joe; Banfield, Mark J; Dennison, Christopher; Robinson, Nigel J

    2008-10-23

    Metals are needed by at least one-quarter of all proteins. Although metallochaperones insert the correct metal into some proteins, they have not been found for the vast majority, and the view is that most metalloproteins acquire their metals directly from cellular pools. However, some metals form more stable complexes with proteins than do others. For instance, as described in the Irving-Williams series, Cu(2+) and Zn(2+) typically form more stable complexes than Mn(2+). Thus it is unclear what cellular mechanisms manage metal acquisition by most nascent proteins. To investigate this question, we identified the most abundant Cu(2+)-protein, CucA (Cu(2+)-cupin A), and the most abundant Mn(2+)-protein, MncA (Mn(2+)-cupin A), in the periplasm of the cyanobacterium Synechocystis PCC 6803. Each of these newly identified proteins binds its respective metal via identical ligands within a cupin fold. Consistent with the Irving-Williams series, MncA only binds Mn(2+) after folding in solutions containing at least a 10(4) times molar excess of Mn(2+) over Cu(2+) or Zn(2+). However once MncA has bound Mn(2+), the metal does not exchange with Cu(2+). MncA and CucA have signal peptides for different export pathways into the periplasm, Tat and Sec respectively. Export by the Tat pathway allows MncA to fold in the cytoplasm, which contains only tightly bound copper or Zn(2+) (refs 10-12) but micromolar Mn(2+) (ref. 13). In contrast, CucA folds in the periplasm to acquire Cu(2+). These results reveal a mechanism whereby the compartment in which a protein folds overrides its binding preference to control its metal content. They explain why the cytoplasm must contain only tightly bound and buffered copper and Zn(2+).

  4. Folded Plate Structures as Building Envelopes

    DEFF Research Database (Denmark)

    Falk, Andreas; Buelow, Peter von; Kirkegaard, Poul Henning

    2012-01-01

    This paper treats applications of cross-laminated timber (CLT) in structural systems for folded façade solutions. Previous work on CLT-based systems for folded roofs has shown a widening range of structural possibilities to develop timber-based shells. Geometric and material properties play...... CLT-based systems, which are studied and analysed by using a combination of digital tools for structural and environmental design and analysis. The results show gainful, rational properties of folded systems and beneficial effects from an integration of architectural and environmental performance...... criteria in the design of CLT-based façades....

  5. A bidirectional shape memory alloy folding actuator

    International Nuclear Information System (INIS)

    Paik, Jamie K; Wood, Robert J

    2012-01-01

    This paper presents a low-profile bidirectional folding actuator based on annealed shape memory alloy sheets applicable for meso- and microscale systems. Despite the advantages of shape memory alloys—high strain, silent operation, and mechanical simplicity—their application is often limited to unidirectional operation. We present a bidirectional folding actuator that produces two opposing 180° motions. A laser-patterned nickel alloy (Inconel 600) heater localizes actuation to the folding sections. The actuator has a thin ( < 1 mm) profile, making it appropriate for use in robotic origami. Various design parameters and fabrication variants are described and experimentally explored in the actuator prototype. (paper)

  6. Melody discrimination and protein fold classification

    Directory of Open Access Journals (Sweden)

    Robert P. Bywater

    2016-10-01

    Full Text Available One of the greatest challenges in theoretical biophysics and bioinformatics is the identification of protein folds from sequence data. This can be regarded as a pattern recognition problem. In this paper we report the use of a melody generation software where the inputs are derived from calculations of evolutionary information, secondary structure, flexibility, hydropathy and solvent accessibility from multiple sequence alignment data. The melodies so generated are derived from the sequence, and by inference, of the fold, in ways that give each fold a sound representation that may facilitate analysis, recognition, or comparison with other sequences.

  7. Mechanical Models of Fault-Related Folding

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, A. M.

    2003-01-09

    The subject of the proposed research is fault-related folding and ground deformation. The results are relevant to oil-producing structures throughout the world, to understanding of damage that has been observed along and near earthquake ruptures, and to earthquake-producing structures in California and other tectonically-active areas. The objectives of the proposed research were to provide both a unified, mechanical infrastructure for studies of fault-related foldings and to present the results in computer programs that have graphical users interfaces (GUIs) so that structural geologists and geophysicists can model a wide variety of fault-related folds (FaRFs).

  8. Multireference Equation of Motion Coupled Cluster study of atomic excitation spectra of first-row transition metal atoms Cr, Mn, Fe and Co

    Czech Academy of Sciences Publication Activity Database

    Liu, Z.; Demel, Ondřej; Nooijen, M.

    2015-01-01

    Roč. 311, SI (2015), s. 54-63 ISSN 0022-2852 Institutional support: RVO:61388955 Keywords : multireference * coupled cluster * electronic excited states Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.593, year: 2015

  9. Exploiting flow injection and sequential injection for trace metal determinations in conjunction with detection by electrothermal atomic absorption spectrometry and inductively coupled plasma mass spectrometry

    DEFF Research Database (Denmark)

    Hansen, Elo Harald

    Despite their excellent analytical chemical capacities, Electrothermal Atomic Absorption Spectrometry (ETAAS) and Inductively Coupled Plasma Mass Spectrometry (ICPMS), nevertheless, often require suitable pretreatment of the sample material in order to obtain the necessary sensitivity...

  10. Self-folding polymeric containers for encapsulation and delivery of drugs.

    Science.gov (United States)

    Fernandes, Rohan; Gracias, David H

    2012-11-01

    Self-folding broadly refers to self-assembly processes wherein thin films or interconnected planar templates curve, roll-up or fold into three dimensional (3D) structures such as cylindrical tubes, spirals, corrugated sheets or polyhedra. The process has been demonstrated with metallic, semiconducting and polymeric films and has been used to curve tubes with diameters as small as 2nm and fold polyhedra as small as 100nm, with a surface patterning resolution of 15nm. Self-folding methods are important for drug delivery applications since they provide a means to realize 3D, biocompatible, all-polymeric containers with well-tailored composition, size, shape, wall thickness, porosity, surface patterns and chemistry. Self-folding is also a highly parallel process, and it is possible to encapsulate or self-load therapeutic cargo during assembly. A variety of therapeutic cargos such as small molecules, peptides, proteins, bacteria, fungi and mammalian cells have been encapsulated in self-folded polymeric containers. In this review, we focus on self-folding of all-polymeric containers. We discuss the mechanistic aspects of self-folding of polymeric containers driven by differential stresses or surface tension forces, the applications of self-folding polymers in drug delivery and we outline future challenges. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. Liquid chromatography coupled to different atmospheric pressure ionization sources-quadrupole-time-of-flight mass spectrometry and post-column addition of metal salt solutions as a powerful tool for the metabolic profiling of Fusarium oxysporum.

    Science.gov (United States)

    Cirigliano, Adriana M; Rodriguez, M Alejandra; Gagliano, M Laura; Bertinetti, Brenda V; Godeas, Alicia M; Cabrera, Gabriela M

    2016-03-25

    Fusarium oxysporum L11 is a non-pathogenic soil-borne fungal strain that yielded an extract that showed antifungal activity against phytopathogens. In this study, reversed-phase high-performance liquid chromatography (RP-HPLC) coupled to different atmospheric pressure ionization sources-quadrupole-time-of-flight mass spectrometry (API-QTOF-MS) was applied for the comprehensive profiling of the metabolites from the extract. The employed sources were electrospray (ESI), atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI). Post-column addition of metal solutions of Ca, Cu and Zn(II) was also tested using ESI. A total of 137 compounds were identified or tentatively identified by matching their accurate mass signals, suggested molecular formulae and MS/MS analysis with previously reported data. Some compounds were isolated and identified by NMR. The extract was rich in cyclic peptides like cyclosporins, diketopiperazines and sansalvamides, most of which were new, and are reported here for the first time. The use of post-column addition of metals resulted in a useful strategy for the discrimination of compound classes since specific adducts were observed for the different compound families. This technique also allowed the screening for compounds with metal binding properties. Thus, the applied methodology is a useful choice for the metabolic profiling of extracts and also for the selection of metabolites with potential biological activities related to interactions with metal ions. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Thermodynamic properties of La-Ga-Al and U-Ga-Al alloys and the separation factor of U/La couple in the molten salt-liquid metal system

    Science.gov (United States)

    Novoselova, A.; Smolenski, V.; Volkovich, V. A.; Ivanov, A. B.; Osipenko, A.; Griffiths, T. R.

    2015-11-01

    The electrochemical behaviour of lanthanum and uranium was studied in fused 3LiCl-2KCl eutectic and Ga-Al eutectic liquid metal alloy between 723 and 823 K. Electrode potentials were recorded vs. Cl-/Cl2 reference electrode and the temperature dependencies of the apparent standard potentials of La-(Ga-Al) and U-(Ga-Al) alloys were determined. Lanthanum and uranium activity coefficients and U/La couple separation factor were calculated. Partial excess free Gibbs energy, partial enthalpy of mixing and partial excess entropy of La-(Ga-Al) and U-(Ga-Al) alloys were estimated.

  13. Folded Resonant Horns for Power Ultrasonic Applications

    Science.gov (United States)

    Sherrit, Stewart; Askins, Stephen; Gradziel, Michael; Bao, Xiaoqi; Chang, Zensheu; Dolgin, Benjamin; Bar-Cohen, Yoseph; Peterson, Tom

    2003-01-01

    Folded horns have been conceived as alternatives to straight horns used as resonators and strain amplifiers in power ultrasonic systems. Such systems are used for cleaning, welding, soldering, cutting, and drilling in a variety of industries. In addition, several previous NASA Tech Briefs articles have described instrumented drilling, coring, and burrowing machines that utilize combinations of sonic and ultrasonic vibrational actuation. The main advantage of a folded horn, relative to a straight horn of the same resonance frequency, is that the folded horn can be made shorter (that is, its greatest linear dimension measured from the outside can be made smaller). Alternatively, for a given length, the resonance frequency can be reduced. Hence, the folded-horn concept affords an additional degree of design freedom for reducing the length of an ultrasonic power system that includes a horn.

  14. Cycle 24 COS/NUV Fold Distribution

    Science.gov (United States)

    Wheeler, Thomas; Welty, Alan

    2018-02-01

    We summarize the Cycle 24 COS/NUV Fold Distribution for the Cosmic Origins Spectrograph's (COS) MAMA detector on the Hubble Space Telescope. The detector micro-channel plate's health state is determined and the results presented.

  15. Topology Explains Why Automobile Sunshades Fold Oddly

    Science.gov (United States)

    Feist, Curtis; Naimi, Ramin

    2009-01-01

    Automobile sunshades always fold into an "odd" number of loops. The explanation why involves elementary topology (braid theory and linking number, both explained in detail here with definitions and examples), and an elementary fact from algebra about symmetric group.

  16. Origami: Paper Folding--The Algorithmic Way.

    Science.gov (United States)

    Heukerott, Pamela Beth

    1988-01-01

    Describes origami, the oriental art of paper folding as an activity to teach upper elementary students concepts and skills in geometry involving polygons, angles, measurement, symmetry, and congruence. (PK)

  17. "Wet" Versus "Dry" Folding of Polyproline

    Science.gov (United States)

    Shi, Liuqing; Holliday, Alison E.; Bohrer, Brian C.; Kim, Doyong; Servage, Kelly A.; Russell, David H.; Clemmer, David E.

    2016-06-01

    When the all- cis polyproline-I helix (PPI, favored in 1-propanol) of polyproline-13 is introduced into water, it folds into the all- trans polyproline-II (PPII) helix through at least six intermediates [Shi, L., Holliday, A.E., Shi, H., Zhu, F., Ewing, M.A., Russell, D.H., Clemmer, D.E.: Characterizing intermediates along the transition from PPI to PPII using ion mobility-mass spectrometry. J. Am. Chem. Soc. 136, 12702-12711 (2014)]. Here, we show that the solvent-free intermediates refold into the all- cis PPI helix with high (>90%) efficiency. Moreover, in the absence of solvent, each intermediate appears to utilize the same small set of pathways observed for the solution-phase PPII → PPI transition upon immersion of PPIIaq in 1-propanol. That folding in solution (under conditions where water is displaced by propanol) and folding in vacuo (where energy required for folding is provided by collisional activation) occur along the same pathway is remarkable. Implicit in this statement is that 1-propanol mimics a "dry" environment, similar to the gas phase. We note that intermediates with structures that are similar to PPIIaq can form PPII under the most gentle activation conditions—indicating that some transitions observed in water (i.e. , "we t" folding, are accessible (albeit inefficient) in vacuo. Lastly, these "dry" folding experiments show that PPI (all cis) is favored under "dry" conditions, which underscores the role of water as the major factor promoting preference for trans proline.

  18. Gyral Folding Pattern Analysis via Surface Profiling

    Science.gov (United States)

    Li, Kaiming; Guo, Lei; Li, Gang; Nie, Jingxin; Faraco, Carlos; Cui, Guangbin; Zhao, Qun; Miller, L. Stephen; Liu, Tianming

    2010-01-01

    Folding is an essential shape characteristic of the human cerebral cortex. Descriptors of cortical folding patterns have been studied for decades. However, many previous studies are either based on local shape descriptors such as curvature, or based on global descriptors such as gyrification index or spherical wavelets. This paper proposes a gyrus-scale folding pattern analysis technique via cortical surface profiling. Firstly, we sample the cortical surface into 2D profiles and model them using a power function. This step provides both the flexibility of representing arbitrary shape by profiling and the compactness of representing shape by parametric modeling. Secondly, based on the estimated model parameters, we extract affine-invariant features on the cortical surface, and apply the affinity propagation clustering algorithm to parcellate the cortex into cortical regions with strict hierarchy and smooth transitions among them. Finally, a second-round surface profiling is performed on the parcellated cortical surface, and the number of hinges is detected to describe the gyral folding pattern. We have applied the surface profiling method to two normal brain datasets and a Schizophrenia patient dataset. The experimental results demonstrate that the proposed method can accurately classify human gyri into 2-hinge, 3-hinge and 4-hinge patterns. The distribution of these folding patterns on brain lobes and the relationship between fiber density and gyral folding patterns are further investigated. Results from the Schizophrenia dataset are consistent with commonly found abnormality in former studies by others, which demonstrates the potential clinical applications of the proposed technique. PMID:20472071

  19. Large gastric folds arising in polyposis syndromes

    Directory of Open Access Journals (Sweden)

    Xiang-Yang Wangz

    2013-08-01

    Full Text Available Large gastric folds (LGF can be caused by benign conditions as well as malignancies. Unfortunately, endoscopic features and biopsy results are often equivocal, making the diagnosis and management of large gastric folds difficult. Polyposis syndromes encompass a group of conditions in which multiple gastrointestinal polyps occur in the lumen of the gut. Large gastric folds are extremely rare in these syndromes. We present the case of a patient with polyposis who was found to have large gastric folds in the entire gastric fundus and body, mimicking malignancy. The patient's medical history and endoscopic ultrasonography (EUS with mucosal resection confirmed the diagnosis of a pre-malignant disease. The lesion was monitored by serial endoscopic ultrasonography and biopsy, abdominal computed tomography (CT, and positron emission and computed tomography (PET-CT for 6 years. The lesion remained stable, with the exception of abnormal fluorodeoxyglucose uptake on PET-CT in the gastric folds, which was determined to be a false-positive sign. To date, the patient remains healthy. We further discuss the mechanisms underlying the formation of large gastric folds caused by polyposis syndromes. Helicobacter pylori (H. pylori or cytomegalovirus (CMV is unnecessary for this progression. Immunohistochemistry (IHC staining suggested that overexpression of transforming growth factor alpha (TGF-α and down-regulation of myocyte enhancer-binding factor 2 (MEF2 may be involved in this case.

  20. Fractal Folding and Medium Viscoelasticity Contribute Jointly to Chromosome Dynamics

    Science.gov (United States)

    Polovnikov, K. E.; Gherardi, M.; Cosentino-Lagomarsino, M.; Tamm, M. V.

    2018-02-01

    Chromosomes are key players of cell physiology, their dynamics provides valuable information about its physical organization. In both prokaryotes and eukaryotes, the short-time motion of chromosomal loci has been described with a Rouse model in a simple or viscoelastic medium. However, little emphasis has been put on the influence of the folded organization of chromosomes on the local dynamics. Clearly, stress propagation, and thus dynamics, must be affected by such organization, but a theory allowing us to extract such information from data, e.g., on two-point correlations, is lacking. Here, we describe a theoretical framework able to answer this general polymer dynamics question. We provide a scaling analysis of the stress-propagation time between two loci at a given arclength distance along the chromosomal coordinate. The results suggest a precise way to assess folding information from the dynamical coupling of chromosome segments. Additionally, we realize this framework in a specific model of a polymer whose long-range interactions are designed to make it fold in a fractal way and immersed in a medium characterized by subdiffusive fractional Langevin motion with a tunable scaling exponent. This allows us to derive explicit analytical expressions for the correlation functions.

  1. Frnakenstein: multiple target inverse RNA folding

    Directory of Open Access Journals (Sweden)

    Lyngsø Rune B

    2012-10-01

    Full Text Available Abstract Background RNA secondary structure prediction, or folding, is a classic problem in bioinformatics: given a sequence of nucleotides, the aim is to predict the base pairs formed in its three dimensional conformation. The inverse problem of designing a sequence folding into a particular target structure has only more recently received notable interest. With a growing appreciation and understanding of the functional and structural properties of RNA motifs, and a growing interest in utilising biomolecules in nano-scale designs, the interest in the inverse RNA folding problem is bound to increase. However, whereas the RNA folding problem from an algorithmic viewpoint has an elegant and efficient solution, the inverse RNA folding problem appears to be hard. Results In this paper we present a genetic algorithm approach to solve the inverse folding problem. The main aims of the development was to address the hitherto mostly ignored extension of solving the inverse folding problem, the multi-target inverse folding problem, while simultaneously designing a method with superior performance when measured on the quality of designed sequences. The genetic algorithm has been implemented as a Python program called Frnakenstein. It was benchmarked against four existing methods and several data sets totalling 769 real and predicted single structure targets, and on 292 two structure targets. It performed as well as or better at finding sequences which folded in silico into the target structure than all existing methods, without the heavy bias towards CG base pairs that was observed for all other top performing methods. On the two structure targets it also performed well, generating a perfect design for about 80% of the targets. Conclusions Our method illustrates that successful designs for the inverse RNA folding problem does not necessarily have to rely on heavy biases in base pair and unpaired base distributions. The design problem seems to become more

  2. Upright folding during extensional and transtensional tectonics

    Science.gov (United States)

    Teyssier, Christian; Fossen, Haakon; Rey, Patrice F.; Whitney, Donna L.

    2017-04-01

    Upright folds are common structures that develop in response to horizontal shortening in layered material, for example in foreland basins that surround orogens. While the contractional nature of these folds is not in doubt, interpretation of their tectonic setting needs careful consideration. Here we focus on two examples: (1) folds developed in transtension; and (2) folds developed during the flow of deep crust in response to lithospheric extension. In both cases we consider folding of nearly horizontal layers that are either primary (bedding) or secondary (foliation). Strain theory inspired by John Ramsay's work makes predictions for the behavior of material lines and planes as well as strain axes (instantaneous, finite) during transtensional deformation. Results show: folds can form in transtension; fold hinges rotate toward the direction of divergence (and not the shear zone boundary as they do in transpression), providing unique insight into ancient plate motions; fold tightness is controlled by the obliquity of divergence and not finite strain; hinge parallel stretching is always greater than hinge-perpendicular shortening, resulting in constriction strain and boudinage of fold hinges. Taken together these results provide a rigorous framework for interpreting field observations where structures are complex and boundary conditions unclear. These principles are applied to various tectonic settings ranging from active tectonic regions of oblique divergence in western North America to ancient folding that developed during oblique extension of the Western Gneiss Region, deposition of Devonian basins, and exhumation of ultrahigh-pressure rocks in the Norwegian Caledonides. The other class of upright folds that form during extension may require revision of the tectonic interpretation of structural overprints in orogenic cores, for example in gneiss/migmatite domes. Dynamic modeling of extension of thick/hot crust predicts a positive feedback between extension of

  3. Viral infections of the folds (intertriginous areas).

    Science.gov (United States)

    Adışen, Esra; Önder, Meltem

    2015-01-01

    Viruses are considered intracellular obligates with a nucleic acid, either RNA or DNA. They have the ability to encode proteins involved in viral replication and production of the protective coat within the host cells but require host cell ribosomes and mitochondria for translation. The members of the families Herpesviridae, Poxviridae, Papovaviridae, and Picornaviridae are the most commonly known agents for the cutaneous viral diseases, but other virus families, such as Adenoviridae, Togaviridae, Parvoviridae, Paramyxoviridae, Flaviviridae, and Hepadnaviridae, can also infect the skin. Though the cutaneous manifestations of viral infections are closely related to the type and the transmission route of the virus, viral skin diseases may occur in almost any part of the body. In addition to friction caused by skin-to-skin touch, skin folds are warm and moist areas of the skin that have limited air circulation. These features provide a fertile breeding ground for many kinds of microorganisms, including bacteria and fungi. In contrast to specific bacterial and fungal agents that have an affinity for the skin folds, except for viral diseases of the anogenital area, which have well-known presentations, viral skin infections that have a special affinity to the skin folds are not known. Many viral exanthems may affect the skin folds during the course of the infection, but here we focus only on the ones that usually affect the fold areas and also on the less well-known conditions or recently described associations. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Bifurcation of self-folded polygonal bilayers

    Science.gov (United States)

    Abdullah, Arif M.; Braun, Paul V.; Hsia, K. Jimmy

    2017-09-01

    Motivated by the self-assembly of natural systems, researchers have investigated the stimulus-responsive curving of thin-shell structures, which is also known as self-folding. Self-folding strategies not only offer possibilities to realize complicated shapes but also promise actuation at small length scales. Biaxial mismatch strain driven self-folding bilayers demonstrate bifurcation of equilibrium shapes (from quasi-axisymmetric doubly curved to approximately singly curved) during their stimulus-responsive morphing behavior. Being a structurally instable, bifurcation could be used to tune the self-folding behavior, and hence, a detailed understanding of this phenomenon is appealing from both fundamental and practical perspectives. In this work, we investigated the bifurcation behavior of self-folding bilayer polygons. For the mechanistic understanding, we developed finite element models of planar bilayers (consisting of a stimulus-responsive and a passive layer of material) that transform into 3D curved configurations. Our experiments with cross-linked Polydimethylsiloxane samples that change shapes in organic solvents confirmed our model predictions. Finally, we explored a design scheme to generate gripper-like architectures by avoiding the bifurcation of stimulus-responsive bilayers. Our research contributes to the broad field of self-assembly as the findings could motivate functional devices across multiple disciplines such as robotics, artificial muscles, therapeutic cargos, and reconfigurable biomedical devices.

  5. Kinetics and Thermodynamics of Membrane Protein Folding

    Directory of Open Access Journals (Sweden)

    Ernesto A. Roman

    2014-03-01

    Full Text Available Understanding protein folding has been one of the great challenges in biochemistry and molecular biophysics. Over the past 50 years, many thermodynamic and kinetic studies have been performed addressing the stability of globular proteins. In comparison, advances in the membrane protein folding field lag far behind. Although membrane proteins constitute about a third of the proteins encoded in known genomes, stability studies on membrane proteins have been impaired due to experimental limitations. Furthermore, no systematic experimental strategies are available for folding these biomolecules in vitro. Common denaturing agents such as chaotropes usually do not work on helical membrane proteins, and ionic detergents have been successful denaturants only in few cases. Refolding a membrane protein seems to be a craftsman work, which is relatively straightforward for transmembrane β-barrel proteins but challenging for α-helical membrane proteins. Additional complexities emerge in multidomain membrane proteins, data interpretation being one of the most critical. In this review, we will describe some recent efforts in understanding the folding mechanism of membrane proteins that have been reversibly refolded allowing both thermodynamic and kinetic analysis. This information will be discussed in the context of current paradigms in the protein folding field.

  6. Comparing Ullmann Coupling on Noble Metal Surfaces: On-Surface Polymerization of 1,3,6,8-Tetrabromopyrene on Cu(111) and Au(111)

    DEFF Research Database (Denmark)

    Pham, Tuan Anh; Song, Fei; Nguyen, Manh-Thuong

    2016-01-01

    to a dissociation of the C−Br bonds and the formation of disordered metal-coordinated molecular networks. Further annealing at 573 K resulted in the formation of covalently linked disordered networks. Importantly, we found that the chosen substrate not only plays an important role as catalyst for the Ullmann...

  7. On-line sample-pre-treatment schemes for trace-level determinations of metals by coupling flow injection or sequential injection with ICP-MS

    DEFF Research Database (Denmark)

    Wang, Jianhua; Hansen, Elo Harald

    2003-01-01

    a polytetrafluoroethylene (PTFE) knotted reactor (KR), solvent extraction-back extraction and hydride/vapor generation. It also addresses a novel, robust approach, whereby the protocol of SI-LOV-bead injection (BI) on-line separation and pre-concentration of ultra-trace levels of metals by a renewable microcolumn...

  8. Pyrazine-functionalized calix[4]arenes: synthesis by palladium-catalyzed cross-coupling with phosphorus pronucleophiles and metal ion extraction properties

    NARCIS (Netherlands)

    Nikishkin, N.; Huskens, Jurriaan; Ansari, S.A.; Mohapatra, P.K.; Verboom, Willem

    2013-01-01

    A series of pyrazine-based calix[4]arene extractants was prepared by a stepwise functionalization, comprising palladium-catalyzed exhaustive cross-coupling of di- and tetrasubstituted calix[4]arenes bearing chloropyrazine moieties. The extraction behavior of the synthesized ligands was studied on

  9. SDEM modelling of fault-propagation folding

    DEFF Research Database (Denmark)

    Clausen, O.R.; Egholm, D.L.; Poulsen, Jane Bang

    2009-01-01

    Understanding the dynamics and kinematics of fault-propagation-folding is important for evaluating the associated hydrocarbon play, for accomplishing reliable section balancing (structural reconstruction), and for assessing seismic hazards. Accordingly, the deformation style of fault-propagation-......Understanding the dynamics and kinematics of fault-propagation-folding is important for evaluating the associated hydrocarbon play, for accomplishing reliable section balancing (structural reconstruction), and for assessing seismic hazards. Accordingly, the deformation style of fault......-propagation-folding has already been the topic of a large number of empirical studies as well as physical and computational model experiments. However, with the newly developed Stress-based Discrete Element Method (SDEM), we have, for the first time, explored computationally the link between self-emerging fault patterns...

  10. Improvement of a Vocal Fold Imaging System

    Energy Technology Data Exchange (ETDEWEB)

    Krauter, K. G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-02-01

    Medical professionals can better serve their patients through continual update of their imaging tools. A wide range of pathologies and disease may afflict human vocal cords or, as they’re also known, vocal folds. These diseases can affect human speech hampering the ability of the patient to communicate. Vocal folds must be opened for breathing and the closed to produce speech. Currently methodologies to image markers of potential pathologies are difficult to use and often fail to detect early signs of disease. These current methodologies rely on a strobe light and slower frame rate camera in an attempt to obtain images as the vocal folds travel over the full extent of their motion.

  11. Kinetics of Peptide Folding in Lipid Membranes

    Science.gov (United States)

    Oh, Kwang-Im; Smith-Dupont, Kathryn B.; Markiewicz, Beatrice N.; Gai, Feng

    2015-01-01

    Despite our extensive understanding of water-soluble protein folding kinetics, much less is known about the folding dynamics and mechanisms of membrane proteins. However, recent studies have shown that for relatively simple systems, such as peptides that form a transmembrane α-helix, helical dimer, or helix-turn-helix, it is possible to assess the kinetics of several important steps, including peptide binding to the membrane from aqueous solution, peptide folding on the membrane surface, helix insertion into the membrane, and helix-helix association inside the membrane. Herein, we provide a brief review of these studies and also suggest new initiation and probing methods that could lead to improved temporal and structural resolution in future experiments. PMID:25808575

  12. Extreme Mechanics: Self-Folding Origami

    Science.gov (United States)

    Santangelo, Christian D.

    2017-03-01

    Origami has emerged as a tool for designing three-dimensional structures from flat films. Because they can be fabricated by lithographic or roll-to-roll processing techniques, they have great potential for the manufacture of complicated geometries and devices. This article discusses the mechanics of origami and kirigami with a view toward understanding how to design self-folding origami structures. Whether an origami structure can be made to fold autonomously depends strongly on the geometry and kinematics of the origami fold pattern. This article collects some of the results on origami rigidity into a single framework, and discusses how these aspects affect the foldability of origami. Despite recent progress, most problems in origami and origami design remain completely open.

  13. Non-cylindrical fold growth in the Zagros fold and thrust belt (Kurdistan, NE-Iraq)

    Science.gov (United States)

    Bartl, Nikolaus; Bretis, Bernhard; Grasemann, Bernhard; Lockhart, Duncan

    2010-05-01

    The Zagros mountains extends over 1800 km from Kurdistan in N-Iraq to the Strait of Hormuz in Iran and is one of the world most promising regions for the future hydrocarbon exploration. The Zagros Mountains started to form as a result of the collision between the Eurasian and Arabian Plates, whose convergence began in the Late Cretaceous as part of the Alpine-Himalayan orogenic system. Geodetic and seismological data document that both plates are still converging and that the fold and thrust belt of the Zagros is actively growing. Extensive hydrocarbon exploration mainly focuses on the antiforms of this fold and thrust belt and therefore the growth history of the folds is of great importance. This work investigates by means of structural field work and quantitative geomorphological techniques the progressive fold growth of the Permam, Bana Bawi- and Safeen- Anticlines located in the NE of the city of Erbil in the Kurdistan region of Northern Iraq. This part of the Zagros fold and thrust belt belongs to the so-called Simply Folded Belt, which is dominated by gentle to open folding. Faults or fault related folds have only minor importance. The mechanical anisotropy of the formations consisting of a succession of relatively competent (massive dolomite and limestone) and incompetent (claystone and siltstone) sediments essentially controls the deformation pattern with open to gentle parallel folding of the competent layers and flexural flow folding of the incompetent layers. The characteristic wavelength of the fold trains is around 10 km. Due to faster erosion of the softer rock layers in the folded sequence, the more competent lithologies form sharp ridges with steeply sloping sides along the eroded flanks of the anticlines. Using an ASTER digital elevation model in combination with geological field data we quantified 250 drainage basins along the different limbs of the subcylindrical Permam, Bana Bawi- and Safeen- Anticlines. Geomorphological indices of the drainage

  14. Symmetric Circular Matchings and RNA Folding

    DEFF Research Database (Denmark)

    Hofacker, Ivo L.; Reidys, Christian; Stadler, Peter F.

    2012-01-01

    or the co-folding of two or more identical RNAs. Here, we show that the RNA folding problem with symmetry terms can still be solved with polynomial-time algorithms. Empirically, the fraction of symmetric ground state structures decreases with chain length, so that the error introduced by neglecting......RNA secondary structures can be computed as optimal solutions of certain circular matching problems. An accurate treatment of this energy minimization problem has to account for the small --- but non-negligible --- entropic destabilization of secondary structures with non-trivial automorphisms...

  15. Stretching and folding mechanism in foams

    Energy Technology Data Exchange (ETDEWEB)

    Tufaile, Alberto [Escola de Artes, Ciencias e Humanidades, Soft Matter Laboratory, Universidade de Sao Paulo, 03828-000 Sao Paulo, SP (Brazil)], E-mail: tufaile@usp.br; Pedrosa Biscaia Tufaile, Adriana [Escola de Artes, Ciencias e Humanidades, Soft Matter Laboratory, Universidade de Sao Paulo, 03828-000 Sao Paulo, SP (Brazil)

    2008-10-13

    We have described the stretching and folding of foams in a vertical Hele-Shaw cell containing air and a surfactant solution, from a sequence of upside-down flips. Besides the fractal dimension of the foam, we have observed the logistic growth for the soap film length. The stretching and folding mechanism is present during the foam formation, and this mechanism is observed even after the foam has reached its respective maximum fractal dimension. Observing the motion of bubbles inside the foam, large bubbles present power spectrum associated with random walk motion in both directions, while the small bubbles are scattered like balls in a Galton board.

  16. Comparison of different transition metal ions for immobilized metal affinity chromatography of selenoprotein P from human plasma

    DEFF Research Database (Denmark)

    Sidenius, U; Farver, O; Jøns, O

    1999-01-01

    Cu2+, Ni2+, Zn2+, Co2+ and Cd2+ were evaluated in metal ion affinity chromatography for enrichment of selenoprotein P, and immobilized Co2+ affinity chromatography was found to be the most selective chromatographic method. The chromatography was performed by fast protein liquid chromatography...... and the fractionation was followed by analysis of the collected fractions for selenium by inductively coupled plasma mass spectrometry. By the combination of immobilized Co2+ affinity chromatography and heparin affinity chromatography a simple method was developed yielding a 14,800-fold enrichment of selenoprotein P...

  17. Study of the leaching of heavy metals from waste water sludge and incinerator's ash, using coupled thermostated columns and DTPA as complex agent; Estudio de la extraccion de metales pesados de lodos y cenizas de aguas residuales usando columnas termostatizadas acopladas y DTPA como agente complejante

    Energy Technology Data Exchange (ETDEWEB)

    Vite T, J.; Vite T, M.; Guerrero D, J.; Carreno de Leon, M.C. [Departamento de Estudios del Ambiente, Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    2000-07-01

    We studied the metallic composition from waste water sludge and incinerators ashes of an incinerator located in Toluca, Mexico, the qualitative studies were made using the Activation Analysis technique, and fluorescence X-ray techniques. The quantitative analysis of heavy metals in the wastes were made using Inductively coupled plasma atomic emission spectrometry (Icp-Aes). For leaching the samples, we used four coupled thermostated columns, each one had a p H of 2,5, 7 and 10. The flux of the air was of 1600 cc/min. The temperature was maintain constant in 60 Centigrade using a thermostated system. For this study we used 100 g of wastes mixed with mineral acid or sodium hydroxide to reach p H 2,5,7 and 10. We added a reducing and tensoactive agents and finally DTPA as complex agent. With this method, we obtain a better leaching efficiency using a complex agent. However the high DTPA cost, make this process expansive that is why we recommend to work with another classes of complex agents, that be cheaper to leach metals of different chemistry matrix. (Author)

  18. Coupling of metal-based light-harvesting antennas and electron-donor subunits: Trinuclear Ruthenium(II) complexes containing tetrathiafulvalene-substituted polypyridine ligands

    DEFF Research Database (Denmark)

    Campagna, Sebastiano; Serroni, Scolastica; Puntoriero, Fausto

    2002-01-01

    as light-harvesting antennas and the tetrathiafulvalene electron donors can induce charge separation. The absorption spectra, redox behavior, and luminescence properties (both at room temperature in acetonitrile and at 77 K in a rigid matrix of butyronitrile) of the trinuclear metal complexes have been......+) (4,4'-Mebpy = 4,4'-dimethyl-2,2'-bipyridine) and [{(bpy)(2)Ru(mu-2,3-dpp)}(2)Ru(bpy)](6+). The absorption spectra and redox behavior of all the new metal compounds can be interpreted by a multicomponent approach, in which specific absorption features and redox processes can be assigned to specific...... subunits of the structures. The luminescence properties of the complexes in rigid matrices at 77 K are very similar to those of the corresponding model compounds without TTF moieties, whereas the new species are nonluminescent, or exhibit very weak emissions relative to those of the model compounds...

  19. An off-line automated preconcentration system with ethylenediaminetriacetate chelating resin for the determination of trace metals in seawater by high-resolution inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    Minami, Tomoharu; Konagaya, Wataru; Zheng, Linjie; Takano, Shotaro; Sasaki, Masanobu; Murata, Rena; Nakaguchi, Yuzuru; Sohrin, Yoshiki

    2015-01-07

    A novel automated off-line preconcentration system for trace metals (Al, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb) in seawater was developed by improving a commercially available solid-phase extraction system SPE-100 (Hiranuma Sangyo). The utilized chelating resin was NOBIAS Chelate-PA1 (Hitachi High-Technologies) with ethylenediaminetriacetic acid and iminodiacetic acid functional groups. Parts of the 8-way valve made of alumina and zirconia in the original SPE-100 system were replaced with parts made of polychlorotrifluoroethylene in order to reduce contamination of trace metals. The eluent pass was altered for the back flush elution of trace metals. We optimized the cleaning procedures for the chelating resin column and flow lines of the preconcentration system, and developed a preconcentration procedure, which required less labor and led to a superior performance compared to manual preconcentration (Sohrin et al.). The nine trace metals were simultaneously and quantitatively preconcentrated from ∼120 g of seawater, eluted with ∼15 g of 1M HNO3, and determined by HR-ICP-MS using the calibration curve method. The single-step preconcentration removed more than 99.998% of Na, K, Mg, Ca, and Sr from seawater. The procedural blanks and detection limits were lower than the lowest concentrations in seawater for Mn, Ni, Cu, and Pb, while they were as low as the lowest concentrations in seawater for Al, Fe, Co, Zn, and Cd. The accuracy and precision of this method were confirmed by the analysis of reference seawater samples (CASS-5, NASS-5, GEOTRACES GS, and GD) and seawater samples for vertical distribution in the western North Pacific Ocean. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Selective coupling of HE{sub 11} and TM{sub 01} modes into microfabricated fully metal-coated quartz probes

    Energy Technology Data Exchange (ETDEWEB)

    Tortora, P. [Institute of Microtechnology, University of Neuchatel, Rue A.L. Breguet 2, CH-2000 Neuchatel (Switzerland)]. E-mail: piero.tortora@unine.ch; Descrovi, E. [Institute of Microtechnology, University of Neuchatel, Rue A.L. Breguet 2, CH-2000 Neuchatel (Switzerland)]. E-mail: emiliano.descrovi@polito.it; Aeschimann, L. [Institute of Microtechnology, University of Neuchatel, Rue A.L. Breguet 2, CH-2000 Neuchatel (Switzerland); Vaccaro, L. [Institute of Microtechnology, University of Neuchatel, Rue A.L. Breguet 2, CH-2000 Neuchatel (Switzerland); Herzig, H.-P. [Institute of Microtechnology, University of Neuchatel, Rue A.L. Breguet 2, CH-2000 Neuchatel (Switzerland); Daendliker, R. [Institute of Microtechnology, University of Neuchatel, Rue A.L. Breguet 2, CH-2000 Neuchatel (Switzerland)

    2007-02-15

    We report computational and experimental investigations on injection and transmission of light in microfabricated fully Aluminum-coated quartz probes. In particular, we show that a selective coupling of either the HE{sub 11} or the TM{sub 01} mode can be carried out by injecting focused linearly or radially polarized beams into the probe. Optical fields, emitted by the probe after a controlled injection, are characterized in intensity and phase with the help of an interferometric technique. With the help of near-field measurement, we finally demonstrate that a longitudinally polarized spot localized at the tip apex is actually produced when the TM{sub 01} mode is coupled into the probe.

  1. Monitoring and assessment of heavy metal/metalloid concentration by inductively coupled plasma mass spectroscopy (ICP-MS) method in Gonyeli Lake, Cyprus.

    Science.gov (United States)

    Alkas, Fehmi Burak; Shaban, Jehad Abdullah; Sukuroglu, Ayca Aktas; Kurt, Mehmet Ali; Battal, Dilek; Saygi, Sahan

    2017-09-22

    The presence of heavy metals/metalloids in the ecosystem has been an increasing ecological and global public health concern due to their potential to cause adverse health effects. For this reason, the accumulation of some heavy metals such as Cr, Mn, Ni, Cu, As, Cd, Pb was assessed by way of ICP-MS in water, sediment and fish (Cyprinus carpio) sampled from Gonyeli Lake, North Cyprus. The results showed that these metals/metalloids are found widespread throughout the study area. In water, most concentrated element was manganese with 92.1 ppb and least concentrated was lead with 0.914 ppb. In sediment, copper had the highest concentration with 613 ppm, and cadmium the lowest with 1.57 ppm. In fish tissues (muscle and gills), the most concentrated element was manganese with 12.5 ppm and the least concentrated cadmium with 0.017 ppm. These results indicate that future remediation efforts are indispensable for the rehabilitation of the lake.

  2. Glueballs as rotating folded closed strings

    Science.gov (United States)

    Sonnenschein, Jacob; Weissman, Dorin

    2015-12-01

    In previous papers [1, 2] we argued that mesons and baryons can be described as rotating open strings in holographic backgrounds. Now we turn to closed strings, which should be the duals of glueballs. We look at the rotating folded closed string in both flat and curved backgrounds.

  3. Vocal fold nodules: morphological and immunohistochemical investigations.

    Science.gov (United States)

    Martins, Regina Helena Garcia; Defaveri, Julio; Custódio Domingues, Maria Aparecida; de Albuquerque E Silva, Rafael; Fabro, Alexandre

    2010-09-01

    The objective of this study was to investigate the morphological and immunohistochemical characteristics of vocal fold nodules. The study design was prospective and retrospective. For the histological study, we reviewed 15 slides from the surgical cases of vocal fold nodules, in which we analyzed epithelium, basal membrane (bm), and lamina propria. For the transmission and scanning electron microscopy (TEM, SEM) studies, five new cases on vocal fold nodules were included. Immunohistochemistry study was carried out in the 15 specimens, using antifibronectin, antilaminin, and anticollagen IV antibodies. The main histological alterations were epithelial hyperplasia (73.33%), basement membrane thickening (86.66%), edema, and fibrosis (93.33%). SEM--reduction in mucous lacing and increase in the desquamating cells, without epithelial erosion. TEM--hyperplasia of the epithelium, enlargement of the intercellular junctions, which was filled by fluid, subepithelial thickening of the lamina reticularis, and break points in the basal membrane. Immunohistochemistry--we identified greater immunoexpression of fibronectin on the basal membrane, on the lamina propria, and around the vessels. Antilaminin and anticollagen IV antibodies showed higher pigmentation on the endothelium of the vessels than that on the basal membrane. In vocal fold nodules, combined assessment using light microscopy, electron microscopy, and immunohistochemistry can reveal important morphological details useful in characterizing these lesions. 2010 The Voice Foundation. Published by Mosby, Inc. All rights reserved.

  4. Assessment of thyroplasty for vocal fold paralysis

    DEFF Research Database (Denmark)

    Grøntved, Ågot Møller; Faber, Christian; Jakobsen, John

    2009-01-01

    INTRODUCTION: Thyroplasty with silicone rubber implantation is a surgical procedure for treatment of patients with vocal fold paralysis. The aim of the present study was to evaluate the outcome of the operation and to monitor which of the analyses were the more beneficial. MATERIAL AND METHODS...

  5. MARATHON DESPITE UNILATERAL VOCAL FOLD PARALYSIS

    Directory of Open Access Journals (Sweden)

    Matthias Echternach

    2008-06-01

    Full Text Available The principal symptoms of unilateral vocal fold paralysis are hoarseness and difficulty in swallowing. Dyspnea is comparatively rare (Laccourreye et al., 2003. The extent to which unilateral vocal fold paralysis may lead to respiratory problems at all - in contrast to bilateral vocal fold paralysis- has not yet well been determined. On the one hand, inspiration is impaired with unilateral vocal fold paralysis; on the other hand, neither the position of the vocal fold paralysis nor the degree of breathiness correlates with respiratory parameters (Cantarella et al., 2003; 2005. The question of what respiratory stress a patient with a vocal fold paresis can endure has not yet been dealt with.A 43 year-old female patient was suffering from recurrent unspecific respiratory complaints for four months after physical activity. During training for a marathon, she experienced no difficulty in breathing. These unspecific respiratory complaints occurred only after athletic activity and persisted for hours. The patient observed neither an increased coughing nor a stridor. Her voice remained unaltered during the attacks, nor were there any signs of a symptomatic gastroesophageal reflux or infectious disease. A cardio-pulmonary and a radiological examination by means of an X-ray of the thorax also revealed no pathological phenomena. As antiallergic and antiobstructive therapy remained unsuccessful, a laryngological examination was performed in order to exclude a vocal cord dysfunction.Surprisingly enough, the laryngostroboscopy showed, as an initial description, a vocal fold paralysis of the left vocal fold in median position (Figure 1. The anamnestic background for the cause was unclear. The only clue was a thoracotomy on the left side due to a pleuritis in childhood. A subsequent laryngoscopic examination had never been performed. Good mucosa waves and amplitudes were shown bilateral with complete glottal closure. Neither in the acoustic analysis, nor in the

  6. Engineering Biology by Controlling Tissue Folding.

    Science.gov (United States)

    Hookway, Tracy A

    2018-04-01

    Achieving complex self-organization in vitro has remained a fundamental challenge in tissue engineering. A recent study in Developmental Cell by Hughes and colleagues uses computational and experimental approaches to understand and control the morphogenic process of tissue folding. These approaches provide an engineering framework to reproducibly control tissue shape. Copyright © 2018 Elsevier Ltd. All rights reserved.

  7. Mapping the universe of RNA tetraloop folds

    DEFF Research Database (Denmark)

    Bottaro, Sandro; Lindorff-Larsen, Kresten

    2017-01-01

    We report a map of RNA tetraloop conformations constructed by calculating pairwise distances among all experimentally determined four-nucleotide hairpin loops. Tetraloops with similar structures are clustered together and, as expected, the two largest clusters are the canonical GNRA and UNCG fold...

  8. Fold in Origami and Unfold Math

    Science.gov (United States)

    Georgeson, Joseph

    2011-01-01

    Students enjoy origami and like making everything from paper cranes to footballs out of small, colorful squares of paper. They can invent their own shapes and are intrigued by the polyhedrons that they can construct. Paper folding is fun, but where is the math? Unless teachers develop lessons that address mathematical objectives, origami could be…

  9. Electric-field-modulated exchange coupling within and between magnetic clusters on metal surfaces: Mn dimers on Cu(1 1 1)

    International Nuclear Information System (INIS)

    Juárez-Reyes, L; Pastor, G M; Stepanyuk, V S

    2014-01-01

    The effects of external electric fields (EFs) on the magnetic state and substrate-mediated magnetic coupling between Mn dimers on Cu(1 1 1) have been studied using a first-principles theoretical method. The calculations show that a change in the ground-state magnetic order, from antiferromagnetic (AF) to ferromagnetic (FM), can be induced within an isolated Mn 2 on Cu(1 1 1) by applying a moderately strong EF of about 1 V Å −1 . The magnetic exchange coupling between pairs of dimers displays Ruderman–Kittel–Kasuya–Yosida-like oscillations as a function of the interdimer distance, which depend significantly on the magnetic order within the dimers (FM or AF) and on their relative orientation on the surface. Moreover, it is observed that applying EFs allows modulation of the exchange coupling within and between the clusters as a function of the intercluster distance. At short distances, AF order within the dimers is favoured even in the presence of EFs, while for large distances the EF can induce a FM order. EFs pointing outwards and inwards with respect to the surface favour parallel and antiparallel magnetic alignment between the dimers, resspectively. The dependence of the substrate-mediated interaction on the magnetic state of Mn 2 is qualitatively interpreted in terms of the differences in the scattering of spin-polarized surface electrons. (paper)

  10. Folding of multidomain proteins: biophysical consequences of tethering even in apparently independent folding.

    Science.gov (United States)

    Arviv, Oshrit; Levy, Yaakov

    2012-12-01

    Most eukaryotic and a substantial fraction of prokaryotic proteins are composed of more than one domain. The tethering of these evolutionary, structural, and functional units raises, among others, questions regarding the folding process of conjugated domains. Studying the folding of multidomain proteins in silico enables one to identify and isolate the tethering-induced biophysical determinants that govern crosstalks generated between neighboring domains. For this purpose, we carried out coarse-grained and atomistic molecular dynamics simulations of two two-domain constructs from the immunoglobulin-like β-sandwich fold. Each of these was experimentally shown to behave as the "sum of its parts," that is, the thermodynamic and kinetic folding behavior of the constituent domains of these constructs seems to occur independently, with the folding of each domain uncoupled from the folding of its partner in the two-domain construct. We show that the properties of the individual domains can be significantly affected by conjugation to another domain. The tethering may be accompanied by stabilizing as well as destabilizing factors whose magnitude depends on the size of the interface, the length, and the flexibility of the linker, and the relative stability of the domains. Accordingly, the folding of a multidomain protein should not be viewed as the sum of the folding patterns of each of its parts, but rather, it involves abrogating several effects that lead to this outcome. An imbalance between these effects may result in either stabilization or destabilization owing to the tethering. Copyright © 2012 Wiley Periodicals, Inc.

  11. Two two-dimensional supergravity theories from Calabi-Yau four-folds

    Energy Technology Data Exchange (ETDEWEB)

    Gates, S. James Jr. E-mail: gatess@wam.umd.edu; Gukov, Sergei E-mail: gukov@feynman.princeton.edu; Witten, Edward

    2000-09-18

    We consider two-dimensional supergravity theories with four supercharges constructed from compactification of Type II string theory on a generic Calabi-Yau four-fold. In type IIA and type IIB cases, respectively, new superspace formulations of N=(2,2) and N=(0,4) dilaton supergravities are found and their coupling to matter multiplets is discussed.

  12. Dynamics study of a three-fold pseudo-Jahn–Teller system using the ...

    Indian Academy of Sciences (India)

    Oppenheimer equations including the geometrical phase effect has been used to study a three-fold pseudo-. Jahn–Teller type electronic ... The linear octahedral T ⊗ (e ⊕ t2). JT system, which couples an electronic triplet state to ... state (T2) with a triply degene- rate normal mode (t2) in systems of tetrahedral or cubic. 115 ...

  13. ETIOLOGICAL FACTORS FOR VOCAL FOLD POLYP FORMATION

    Directory of Open Access Journals (Sweden)

    DAŠA GLUVAJIĆ

    2016-05-01

    Full Text Available Background: Vocal fold polyp is one of the most common causes for hoarseness. Many different etiological factors contribute to vocal fold polyp formation. The aim of the study was to find out whether the etiological factors for polyp formation have changed in the last 30 years.Methods: Eighty-one patients with unilateral vocal fold polyp were included in the study. A control group was composed of 50 volunteers without voice problems who matched the patients by age and gender. The data about etiological factors and the findings of phoniatric examination were obtained from the patients' medical documentation and from the questionnaires for the control group. The incidence of etiological factors was compared between the two groups. The program SPSS, Version 18 was used for statistical analysis.Results: The most frequent etiological factors were occupational voice load, GER, allergy and smoking. In 79% of patients 2 – 6 contemporary acting risk factors were found. Occupational voice load (p=0,018 and GER (p=0,004 were significantly more frequent in the patients than in the controls. The other factors did not significantly influence the polyp formation.Conclusions: There are several factors involved simultaneously in the formation of vocal fold polyps both nowadays and 30 years ago. Some of the most common factors remain the same (voice load, smoking, others are new (GER, allergy, which is probably due to the different lifestyle and working conditions than 30 years ago. Occupational voice load and GER were significantly more frequently present in the patients with polyp than in the control group. Regarding the given results it is important to instruct workers with professional vocal load about etiological factors for vocal fold polyp formation.

  14. Inverse folding of RNA pseudoknot structures

    Directory of Open Access Journals (Sweden)

    Li Linda YM

    2010-06-01

    Full Text Available Abstract Background RNA exhibits a variety of structural configurations. Here we consider a structure to be tantamount to the noncrossing Watson-Crick and G-U-base pairings (secondary structure and additional cross-serial base pairs. These interactions are called pseudoknots and are observed across the whole spectrum of RNA functionalities. In the context of studying natural RNA structures, searching for new ribozymes and designing artificial RNA, it is of interest to find RNA sequences folding into a specific structure and to analyze their induced neutral networks. Since the established inverse folding algorithms, RNAinverse, RNA-SSD as well as INFO-RNA are limited to RNA secondary structures, we present in this paper the inverse folding algorithm Inv which can deal with 3-noncrossing, canonical pseudoknot structures. Results In this paper we present the inverse folding algorithm Inv. We give a detailed analysis of Inv, including pseudocodes. We show that Inv allows to design in particular 3-noncrossing nonplanar RNA pseudoknot 3-noncrossing RNA structures-a class which is difficult to construct via dynamic programming routines. Inv is freely available at http://www.combinatorics.cn/cbpc/inv.html. Conclusions The algorithm Inv extends inverse folding capabilities to RNA pseudoknot structures. In comparison with RNAinverse it uses new ideas, for instance by considering sets of competing structures. As a result, Inv is not only able to find novel sequences even for RNA secondary structures, it does so in the context of competing structures that potentially exhibit cross-serial interactions.

  15. Folding and Fracturing of Rocks: the background

    Science.gov (United States)

    Ramsay, John G.

    2017-04-01

    This book was generated by structural geology teaching classes at Imperial College. I was appointed lecturer during 1957 and worked together with Dr Gilbert Wilson teaching basic structural geology at B.Sc level. I became convinced that the subject, being essentially based on geometric field observations, required a firm mathematical basis for its future development. In particular it seemed to me to require a very sound understanding of stress and strain. My field experience suggested that a knowledge of two- and three-demensional strain was critical in understanding natural tectonic processes. I found a rich confirmation for this in early publications of deformed fossils, oolitic limestones and spotted slates made by several geologists around the beginning of the 20th century (Sorby, Philips, Haughton, Harker) often using surprisingly sophisticated mathematical methods. These methods were discussed and elaborated in Folding and Fracturing of Rocks in a practical way. The geometric features of folds were related to folding mechanisms and the fold related small scale structures such as cleavage, schistosity and lineation explained in terms of rock strain. My work in the Scottish Highlands had shown just how repeated fold superposition could produce very complex geometric features, while further work in other localities suggested that such geometric complications are common in many orogenic zones. From the development of structural geological studies over the past decades it seems that the readers of this book have found many of the ideas set out are still of practical application. The mapping of these outcrop-scale structures should be emphasised in all field studies because they can be seen as ''fingerprints'' of regional scale tectonic processes. My own understanding of structural geology has been inspired by field work and I am of the opinion that future progress in understanding will be likewise based on careful observation and measurement of the features of

  16. Subcision Using a Spinal Needle Cannula and a Thread for Prominent Nasolabial Fold Correction

    Directory of Open Access Journals (Sweden)

    Sang-Yeul Lee

    2013-05-01

    Full Text Available Deepening of the nasolabial crease is an esthetically unpleasing aging phenomenon occurring in the midface. Various treatment modalities have been introduced to improve the appearance of prominent nasolabial folds, all of which have pros and cons. Currently, a minimally invasive technique using synthetic dermal fillers is most commonly used. A simple and easy subcision procedure using a wire scalpel has also been used and reported to be effective for prominent nasolabial fold correction, with minimal complications. As an alternative to the wire scalpel, we used a 20-gauge metal type spinal needle cannula (Hakko Co. and 4-0 Vicryl suture (Ethicon Inc. for subcision of nasolabial folds. This technique is less expensive than the use of a wire scalpel and easily available when needed. Therefore, on the basis of favorable results, our modified subcision technique may be considered effective for prominent nasolabial fold correction.

  17. Plasmon-Coupled Whispering Gallery Modes on Nanodisk Arrays for Signal Enhancements.

    Science.gov (United States)

    Kang, Tae Young; Lee, Wonju; Ahn, Heesang; Shin, Dong-Myeong; Kim, Chang-Seok; Oh, Jin-Woo; Kim, Donghyun; Kim, Kyujung

    2017-09-15

    Metallic nanostructures including single and double nanodisks are successfully used to enhance the localized electric field in vicinity of microcavity in whispering gallery mode (WGM) sensor. We demonstrate numerical calculations of plasmonic coupling of WGMs to single and double nanodisk arrays on a planar substrate. We then experimentally confirmed that the resonance wavelength of WGM sensor was dramatically shifted by adoption of single and double nanodisks on the surface of microcavity in the WGM sensor. Thus, our approach provides the tunable sensitivity of WGM sensor, and has a great potential to be used in numerous areas where the single biomolecule, protein-protein folding and biomolecular interactions are involved.

  18. Detection, in real time, of metallic pollutants present in the industrial atmospheric effluents by inductively coupled plasma torch; Detection, en temps reel, d'elements metalliques presents dans les rejets atmospheriques industriels par torche a plasma a couplage inductif

    Energy Technology Data Exchange (ETDEWEB)

    Vacher, D.

    2001-12-15

    This work is devoted to the development of a process of detection in real time of metallic pollutants present in industrial atmospheric effluents. The method of measurement is the atomic spectrometry of emission coupled to an ICP torch (Inductively coupled Plasma). The technology of the fluidized beds is used as system of introduction of the metallic particles into the ICP torch, the interest of the principle of detection resting on the stamping from the usual procedure of calibration of the analytical system. The results are presented in two parts. The first relates to the diagnosis of plasmas formed with various mixtures of N{sub 2}/O{sub 2} which one corresponds to pure air, the second presents the setting process of detection in real time starting from the intensities ratios of the spectral lines of the metallic element with those of the plasma-producing element (argon or pure air) The study of the diagnosis of plasmas made up of mixtures N{sub 2}/O{sub 2} relates to the determination of the atomic excitation temperature from the spectral lines of the copper element and the evaluation of the thermal disequilibrium q Te/Th. This last is obtained by considering the mass enthalpy of various mixtures N{sub 2}/O{sub 2}. The existence of a small thermal disequilibrium is highlighted. The study of detection in real time by ICP torch, without calibration of the system, is based on three points: - spectroscopic data processing to determine the values of the intensities ratios of spectral lines; - the insertion of the intensities ratios and the characteristics of plasma (argon or pure air) into a calculation code of plasma composition; - the comparison of the mass flux values of the metallic pollutants, in real time, obtained by experiments with those resulting from the elutriation calculation, term which defines the phenomenon of entrainment of the particles out of the fluidized bed. The results made it possible to show the similarity of the analytical system response

  19. Design and Optimization of a Millimetre Wave Compact Folded Magic-T

    Directory of Open Access Journals (Sweden)

    Guang Hua

    2012-01-01

    Full Text Available A millimetre wave-folded magic-T junction compensated with metal cone is designed using a particle swarm optimization (PSO algorithm. An off-centred metallic frustum was used to enhance the bandwidth and a metallic post is used to compensate the mismatched E-arm. The geometrical parameters of the frustum and the post are optimized by PSO. The optimized magic-T for W-band application is designed and tested. The design features are simple in structure and easy to fabricate. The 2% bandwidth with centre frequency of 94 GHz and return loss less than −20 dB is achieved.

  20. Analysis of trace metals (Cu, Cd, Pb, and Fe) in seawater using single batch nitrilotriacetate resin extraction and isotope dilution inductively coupled plasma mass spectrometry

    International Nuclear Information System (INIS)

    Lee, Jong-Mi; Boyle, Edward A.; Echegoyen-Sanz, Yolanda; Fitzsimmons, Jessica N.; Zhang Ruifeng; Kayser, Richard A.

    2011-01-01

    A simple and accurate low-blank method has been developed for the analysis of total dissolved copper, cadmium, lead, and iron in a small volume (1.3-1.5 mL per element) of seawater. Pre-concentration and salt-separation of a stable isotope spiked sample are achieved by single batch extraction onto nitrilotriacetate (NTA)-type Superflow chelating resin beads (100-2400 beads depending on the element). Metals are released into 0.1-0.5 M HNO 3 , and trace metal isotope ratios are determined by ICPMS. The benefit of this method compared to our previous Mg(OH) 2 coprecipitation method is that the final matrix is very dilute so cone-clogging and matrix sensitivity suppression are minimal, while still retaining the high accuracy of the isotope dilution technique. Recovery efficiencies are sensitive to sample pH, number of resin beads added, and the length of time allowed for sample-resin binding and elution; these factors are optimized for each element to yield the highest recovery. The method has a low procedural blank and high sensitivity sufficient for the analysis of pM-nM open-ocean trace metal concentrations. Application of this method to samples from the Bermuda Atlantic Time-Series Study station provides oceanographically consistent Cu, Cd, Pb, and Fe profiles that are in good agreement with other reliable data for this site. In addition, the method can potentially be modified for the simultaneous analysis of multiple elements, which will be beneficial for the analysis of large number of samples.

  1. Analysis of trace metals (Cu, Cd, Pb, and Fe) in seawater using single batch nitrilotriacetate resin extraction and isotope dilution inductively coupled plasma mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong-Mi [Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Boyle, Edward A., E-mail: eaboyle@mit.edu [Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Echegoyen-Sanz, Yolanda; Fitzsimmons, Jessica N. [Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Zhang Ruifeng [State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062 (China); Kayser, Richard A. [Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2011-02-07

    A simple and accurate low-blank method has been developed for the analysis of total dissolved copper, cadmium, lead, and iron in a small volume (1.3-1.5 mL per element) of seawater. Pre-concentration and salt-separation of a stable isotope spiked sample are achieved by single batch extraction onto nitrilotriacetate (NTA)-type Superflow chelating resin beads (100-2400 beads depending on the element). Metals are released into 0.1-0.5 M HNO{sub 3}, and trace metal isotope ratios are determined by ICPMS. The benefit of this method compared to our previous Mg(OH){sub 2} coprecipitation method is that the final matrix is very dilute so cone-clogging and matrix sensitivity suppression are minimal, while still retaining the high accuracy of the isotope dilution technique. Recovery efficiencies are sensitive to sample pH, number of resin beads added, and the length of time allowed for sample-resin binding and elution; these factors are optimized for each element to yield the highest recovery. The method has a low procedural blank and high sensitivity sufficient for the analysis of pM-nM open-ocean trace metal concentrations. Application of this method to samples from the Bermuda Atlantic Time-Series Study station provides oceanographically consistent Cu, Cd, Pb, and Fe profiles that are in good agreement with other reliable data for this site. In addition, the method can potentially be modified for the simultaneous analysis of multiple elements, which will be beneficial for the analysis of large number of samples.

  2. Optical design of transparent thin metal electrodes to enhance in-coupling and trapping of light in flexible polymer solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Salinas, Jose-Francisco [Department of Material Science and Engineering, University of Washington, Seattle, Washington, 98195 (United States); Centro de Investigaciones en Optica A.P.1-948, Leon, Guanajuato, CP 37000 (Mexico); Yip, Hin-Lap; Chueh, Chu-Chen; Li, Chang-Zhi; Jen, Alex K.Y. [Department of Material Science and Engineering, University of Washington, Seattle, Washington, 98195 (United States); Maldonado, Jose-Luis [Centro de Investigaciones en Optica A.P.1-948, Leon, Guanajuato, CP 37000 (Mexico)

    2012-12-11

    ITO-free polymer solar cells with efficiencies as high as 6.6% and 5.8% are fabricated on glass and polyethylene naphthalate (PEN) by using TeO{sub 2} to enhance the in-coupling of light in an Ag-Ag microcavity. These cells exhibit higher performance, selective microcavity resonance as a function of the thickness of TeO{sub 2}, and better bending stability than flexible devices made with ITO. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Enzyme-mediated site-specific bioconjugation of metal complexes to proteins: sortase-mediated coupling of copper-64 to a single-chain antibody.

    Science.gov (United States)

    Paterson, Brett M; Alt, Karen; Jeffery, Charmaine M; Price, Roger I; Jagdale, Shweta; Rigby, Sheena; Williams, Charlotte C; Peter, Karlheinz; Hagemeyer, Christoph E; Donnelly, Paul S

    2014-06-10

    The enzyme-mediated site-specific bioconjugation of a radioactive metal complex to a single-chain antibody using the transpeptidase sortase A is reported. Cage amine sarcophagine ligands that were designed to function as substrates for the sortase A mediated bioconjugation to antibodies were synthesized and enzymatically conjugated to a single-chain variable fragment. The antibody fragment scFv(anti-LIBS) targets ligand-induced binding sites (LIBS) on the glycoprotein receptor GPIIb/IIIa, which is present on activated platelets. The immunoconjugates were radiolabeled with the positron-emitting isotope (64)Cu. The new radiolabeled conjugates were shown to bind selectively to activated platelets. The diagnostic potential of the most promising conjugate was demonstrated in an in vivo model of carotid artery thrombosis using positron emission tomography. This approach gives homogeneous products through site-specific enzyme-mediated conjugation and should be broadly applicable to other metal complexes and proteins. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Sustainable Utilization of Bio waste towards the Green Synthesis of Nanoparticles and its Utility in the Naked Eye Detection of Metals Coupled with its Larvicidal and Antimicrobial Properties

    Science.gov (United States)

    Nikhila, P. S.; Satheesh, Namitha; Sreejitha, V. S.; Pillai, Anandu R.; Saritha, A.; Smitha Chandran, S.

    2018-02-01

    Green synthesis of nanoparticles has become a prominent zone of attention in the field of nanotechnology, as it is a nontoxic, economically feasible and green approach. In the present work we have developed an eco-friendly and zero cost method for the synthesis of silver nanoparticles using common a bio waste banana blossom peel. The well-known characteristic phenomenon of surface Plasmon resonance (SPR) has been exploited towards the characterization of the green synthesized nanoparticles. The aforementioned nanoparticles were characterized by UV spectroscopy and the behaviour of these particles towards naked eye detection of metal ions were observed. The sensitivity of the nanoparticles towards the detection of metal ions was carefully monitored by the shift in the SPR band. Moreover the larvicidal potential of these green synthesized silver nanoparticles were evaluated as per WHO standards. The synthesized silver nanoparticles were found to be an effective antibacterial agent against Gram negative bacteria-E.coli. The method we followed for the synthesis of silver nanoparticles is economically feasible as well as environment friendly and also capable of rapid synthesis of nanoparticles at ambient conditions.

  5. Folding pathways explored with artificial potential functions

    International Nuclear Information System (INIS)

    Ulutaş, B; Bozma, I; Haliloglu, T

    2009-01-01

    This paper considers the generation of trajectories to a given protein conformation and presents a novel approach based on artificial potential functions—originally proposed for multi-robot navigation. The artificial potential function corresponds to a simplified energy model, but with the novelty that—motivated by work on robotic navigation—a nonlinear compositional scheme of constructing the energy model is adapted instead of an additive formulation. The artificial potential naturally gives rise to a dynamic system for the protein structure that ensures collision-free motion to an equilibrium point. In cases where the equilibrium point is the native conformation, the motion trajectory corresponds to the folding pathway. This framework is used to investigate folding in a variety of protein structures, and the results are compared with those of other approaches including experimental studies

  6. Ca-Dependent Folding of Human Calumenin

    Science.gov (United States)

    Mazzorana, Marco; Hussain, Rohanah; Sorensen, Thomas

    2016-01-01

    Human calumenin (hCALU) is a six EF-hand protein belonging to the CREC family. As other members of the family, it is localized in the secretory pathway and regulates the activity of SERCA2a and of the ryanodine receptor in the endoplasmic reticulum (ER). We have studied the effects of Ca2+ binding to the protein and found it to attain a more compact structure upon ion binding. Circular Dichroism (CD) measurements suggest a major rearrangement of the protein secondary structure, which reversibly switches from disordered at low Ca2+ concentrations to predominantly alpha-helical when Ca2+ is added. SAXS experiments confirm the transition from an unfolded to a compact structure, which matches the structural prediction of a trilobal fold. Overall our experiments suggest that calumenin is a Ca2+ sensor, which folds into a compact structure, capable of interacting with its molecular partners, when Ca2+ concentration within the ER reaches the millimolar range. PMID:26991433

  7. Thermostable exoshells fold and stabilize recombinant proteins.

    Science.gov (United States)

    Deshpande, Siddharth; Masurkar, Nihar D; Girish, Vallerinteavide Mavelli; Desai, Malan; Chakraborty, Goutam; Chan, Juliana M; Drum, Chester L

    2017-11-13

    The expression and stabilization of recombinant proteins is fundamental to basic and applied biology. Here we have engineered a thermostable protein nanoparticle (tES) to improve both expression and stabilization of recombinant proteins using this technology. tES provides steric accommodation and charge complementation to green fluorescent protein (GFPuv), horseradish peroxidase (HRPc), and Renilla luciferase (rLuc), improving the yields of functional in vitro folding by ~100-fold. Encapsulated enzymes retain the ability to metabolize small-molecule substrates, presumably via four 4.5-nm pores present in the tES shell. GFPuv exhibits no spectral shifts in fluorescence compared to a nonencapsulated control. Thermolabile proteins internalized by tES are resistant to thermal, organic, chaotropic, and proteolytic denaturation and can be released from the tES assembly with mild pH titration followed by proteolysis.

  8. Cutting and Folding for Tunable Materials Properties

    Science.gov (United States)

    Damasceno, Pablo; Dodd, Paul; Shyu, Terry; Shlian, Matthew; Shtein, Max; Kotov, Nicholas; Glotzer, Sharon

    2014-03-01

    Despite the small set of building blocks used for their assembly, naturally occurring materials such as proteins show remarkable diversity in their mechanical properties ranging from something resembling rubber-low stiffness, high resilience and extensibility-to silk-high stiffness and strength. Moreover, their self-folding properties inspire the design of structures capable of tunable reconfiguration. Motivated by such versatility, we report on simulations and experiments for the design of nanocomposites sheets whose mechanical properties can be made tunable via ``secondary structures'' patterning. Our simulations reveal the main cutting features needed to obtain desired material extensibility. Additionally, we study how similar sheets could self-fold into their desired ``native'' structure via stochastic forces. Our results open the possibilities for manufacture of flexible and reconfigurable materials with targeted strength and extensibility. Research supported by the National Science Foundation, Emerging Frontiers in Research and Innovation Award # EFRI-1240264.

  9. Self-folding micropatterned polymeric containers.

    Science.gov (United States)

    Azam, Anum; Laflin, Kate E; Jamal, Mustapha; Fernandes, Rohan; Gracias, David H

    2011-02-01

    We demonstrate self-folding of precisely patterned, optically transparent, all-polymeric containers and describe their utility in mammalian cell and microorganism encapsulation and culture. The polyhedral containers, with SU-8 faces and biodegradable polycaprolactone (PCL) hinges, spontaneously assembled on heating. Self-folding was driven by a minimization of surface area of the liquefying PCL hinges within lithographically patterned two-dimensional (2D) templates. The strategy allowed for the fabrication of containers with variable polyhedral shapes, sizes and precisely defined porosities in all three dimensions. We provide proof-of-concept for the use of these polymeric containers as encapsulants for beads, chemicals, mammalian cells and bacteria. We also compare accelerated hinge degradation rates in alkaline solutions of varying pH. These optically transparent containers resemble three-dimensional (3D) micro-Petri dishes and can be utilized to sustain, monitor and deliver living biological components.

  10. Unit operations of tissue development: epithelial folding.

    Science.gov (United States)

    Zartman, Jeremiah J; Shvartsman, Stanislav Y

    2010-01-01

    The development of multicellular organisms relies on a small set of construction techniques-assembly, sculpting, and folding-that are spatially and temporally regulated in a combinatorial manner to produce the diversity of tissues within the body. These basic processes are well conserved across tissue types and species at the level of both genes and mechanisms. Here we review the signaling, patterning, and biomechanical transformations that occur in two well-studied model systems of epithelial folding to illustrate both the complexity and modularity of tissue development. In particular, we discuss the possibility of a spatial code specifying morphogenesis. To decipher this code, engineers and scientists need to establish quantitative experimental systems and to develop models that address mechanisms at multiple levels of organization, from gene sequence to tissue biomechanics. In turn, quantitative models of embryogenesis can inspire novel methods for creating synthetic organs and treating degenerative tissue diseases.

  11. Reduction of intergranular exchange coupling and grain size for high Ku CoPt-based granular media: Metal-oxide buffer layer and multiple oxide boundary materials

    Science.gov (United States)

    Tham, Kim Kong; Kushibiki, Ryosuke; Kamada, Tomonari; Hinata, Shintaro; Saito, Shin

    2018-05-01

    Investigation of magnetic properties and microstructure of granular media with various multiple oxides as the grain boundary material is reported. Saturation magnetization (Ms), uniaxial magnetocrystalline anisotropy (Ku), and magnetic grain diameter (GD) of the granular media show linear correlation with volume weighted average for melting point (Tm) of each oxides (Tmave). Ku of magnetic grains (Kugrain) shows a trade-off relation with GD that it is a big challenge to satisfy both high Kugrain and small GD by only controlling Tmave. To obtain a granular medium with appropriate Kugrain, GD, and low degree of intergranular exchange coupling, the combination of Tmave control of grain boundary material by mixing oxides and employment of a buffer layer are required. Here the degree of intergranular exchange coupling is estimated from the slope of M-H loop at around coercivity (α). By applying this technique, a typical granular medium with Kugrain of 1.0×107 erg/cm3, GD of 5.1 nm, and α of 1.2 is realized.

  12. Au3+/Au0 Supported on Chromium(III Terephthalate Metal Organic Framework (MIL-101 as an Efficient Heterogeneous Catalystfor Three-Component Coupling Synthesis of Propargylamines

    Directory of Open Access Journals (Sweden)

    Lili Liu

    2017-01-01

    Full Text Available Post-synthesis modification is a useful method for the functionalization of metal–organic frameworks (MOFs. A novel catalyst Au@MIL-101-ED-SA (ED = ethylenediamine, SA = salicylaldehyde, containing coexisting Au3+ ions and Au0 nanoparticles, was prepared successfully by post-synthesis modification with ethylenediamine, salicylaldehyde and gold. Gold nanoparticles supported on MIL-101 (Au@MIL-101 were prepared successfully by the impregnation method. Au@MIL-101-ED-SA and Au@MIL-101 were characterized by N2 adsorption–desorption, X-ray diffraction, infrared spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, and inductively coupled plasma-optical emission spectrometry. Au@MIL-101-ED-SA and Au@MIL-101 were applied as environmentally friendly catalysts in the three-component coupling reaction of aldehydes, amines, and alkynes for the preparation of diverse propargylamines. Au@MIL-101-ED-SA contained a fraction of cationic gold (Au3+/Au0 = 0.9 and showed higher catalytic activity than Au@MIL-101, which was prepared by the impregnation method. Furthermore, the reactions were performed under heterogeneous conditions and the novel catalyst was successfully recycled for four consecutive runs.

  13. PREFACE Protein folding: lessons learned and new frontiers Protein folding: lessons learned and new frontiers

    Science.gov (United States)

    Pappu, Rohit V.; Nussinov, Ruth

    2009-03-01

    In appropriate physiological milieux proteins spontaneously fold into their functional three-dimensional structures. The amino acid sequences of functional proteins contain all the information necessary to specify the folds. This remarkable observation has spawned research aimed at answering two major questions. (1) Of all the conceivable structures that a protein can adopt, why is the ensemble of native-like structures the most favorable? (2) What are the paths by which proteins manage to robustly and reproducibly fold into their native structures? Anfinsen's thermodynamic hypothesis has guided the pursuit of answers to the first question whereas Levinthal's paradox has influenced the development of models for protein folding dynamics. Decades of work have led to significant advances in the folding problem. Mean-field models have been developed to capture our current, coarse grain understanding of the driving forces for protein folding. These models are being used to predict three-dimensional protein structures from sequence and stability profiles as a function of thermodynamic and chemical perturbations. Impressive strides have also been made in the field of protein design, also known as the inverse folding problem, thereby testing our understanding of the determinants of the fold specificities of different sequences. Early work on protein folding pathways focused on the specific sequence of events that could lead to a simplification of the search process. However, unifying principles proved to be elusive. Proteins that show reversible two-state folding-unfolding transitions turned out to be a gift of natural selection. Focusing on these simple systems helped researchers to uncover general principles regarding the origins of cooperativity in protein folding thermodynamics and kinetics. On the theoretical front, concepts borrowed from polymer physics and the physics of spin glasses led to the development of a framework based on energy landscape theories. These

  14. Protein Folding: Search for Basic Physical Models

    Directory of Open Access Journals (Sweden)

    Ivan Y. Torshin

    2003-01-01

    Full Text Available How a unique three-dimensional structure is rapidly formed from the linear sequence of a polypeptide is one of the important questions in contemporary science. Apart from biological context of in vivo protein folding (which has been studied only for a few proteins, the roles of the fundamental physical forces in the in vitro folding remain largely unstudied. Despite a degree of success in using descriptions based on statistical and/or thermodynamic approaches, few of the current models explicitly include more basic physical forces (such as electrostatics and Van Der Waals forces. Moreover, the present-day models rarely take into account that the protein folding is, essentially, a rapid process that produces a highly specific architecture. This review considers several physical models that may provide more direct links between sequence and tertiary structure in terms of the physical forces. In particular, elaboration of such simple models is likely to produce extremely effective computational techniques with value for modern genomics.

  15. Folding Membrane Proteins by Deep Transfer Learning

    KAUST Repository

    Wang, Sheng

    2017-08-29

    Computational elucidation of membrane protein (MP) structures is challenging partially due to lack of sufficient solved structures for homology modeling. Here, we describe a high-throughput deep transfer learning method that first predicts MP contacts by learning from non-MPs and then predicts 3D structure models using the predicted contacts as distance restraints. Tested on 510 non-redundant MPs, our method has contact prediction accuracy at least 0.18 better than existing methods, predicts correct folds for 218 MPs, and generates 3D models with root-mean-square deviation (RMSD) less than 4 and 5 Å for 57 and 108 MPs, respectively. A rigorous blind test in the continuous automated model evaluation project shows that our method predicted high-resolution 3D models for two recent test MPs of 210 residues with RMSD ∼2 Å. We estimated that our method could predict correct folds for 1,345–1,871 reviewed human multi-pass MPs including a few hundred new folds, which shall facilitate the discovery of drugs targeting at MPs.

  16. Araguaia fold belt, new geochronological data

    International Nuclear Information System (INIS)

    Lafon, J.M.; Macambira, J.B.; Macambira, M.J.B.; Moura, C.A.V.; Souza, A.C.C.

    1990-01-01

    The northern part of the Araguaia Fold Belt (AFB) outcrops in a N-S direction for about 400 km in the state of Tocantins. Dome-like structures occur in this fold belt also in a N-S direction. Both deformation and metamorphism increase from the West to the East. The basement of the AFB consist of Colmeia complex and Cantao gneiss, which crop out mainly in the core of the dome-like structures. The supracrustals rocks of the fold belt belongs to the Baixo Araguaia supergroup which is divided into the lower Estrondo group and the upper Tocantins group. Preliminary Sm-Nd data from the Colmeia complex (Grota Rica dome) gave Archean model ages of 2.8 Ga (TNd sub(DM)) while Rb-Sr data in the same rocks give an age of 2530 ± 200 Ma. In the others dome-like structures, the Rb-Sr systematics gave ages for the Colmeia a complex of 2239 ± 47 Ma (Colmeia structure) and 1972 ± 46 Ma (Lontra structure). These younger ages are believed to represent partial to total isotopic resetting of the Rb-Sr system during the Transamazonian Event. The Rb-Sr studies of the Cantao gneiss gave an age of 1774 ± 31 Ma. (author)

  17. Effects of surface processes on multilayer detachment folding: a numerical approach

    Science.gov (United States)

    Collignon, M.; May, D.; Kaus, B.; Fernandez, N.

    2013-12-01

    Over the past decades, the interaction between surface processes and development of mountain belts has been extensively studied. While syntectonic sedimentation appears to control the external development of the fold-and-thrust belts, erosion strongly influences the evolution of internal regions within mountain belts. The effects of surface processes on brittle deformation have been thoroughly studied using analogue and numerical models of accretionary wedges, however, most of the numerical studies used a 2D model of deformation and/or a simple formulation for the surface processes, where both sedimentation and erosion are rarely present together. Coupled analogue models of deformation and surface processes are challenging, due to material and scaling issues, and often only reproduce two end-member cases (no erosion vs very strong erosion, where all the material is removed), but fail to investigate the transitional cases. In contrast, interactions between surface processes and ductile deformation (e.g. multilayer detachment folding) have been poorly investigated. Thin-skinned fold and thrust belts are seen as the result of compressional deformation of a sediment pile over a weak layer acting as a décollement level. The resulting surface expression has often been interpreted, based on geometrical criteria in terms of fault bend folds, propagation folds and/or detachment folds. A few analogue studies have demonstrated that fold morphology can be influenced by erosion rates or preferential localization of sedimentation, and additionally, that the fold growth can be stopped by increasing the supply of sediments. Here we aim to numerically investigate the effects of surface processes and multilayer folding in three dimensions. For this purpose, we have developed a finite-element based landscape evolution model (both erosion and sedimentation) using PETSc, and coupled it to the 3D mechanical code LaMEM. The landscape evolution model uses a non-linear diffusion

  18. Application of laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) to investigate trace metal spatial distributions in human tooth enamel and dentine growth layers and pulp

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Daniel; Amarasiriwardena, Dulasiri; Goodman, Alan H. [School of Natural Science, Hampshire College, 01002, Amherst, MA (United States)

    2004-03-01

    Human tooth enamel provides a nearly permanent and chronological record of an individual's nutritional status and anthropogenic trace metal exposure during development; it might thus provide an excellent bio archive. We investigated the micro-spatial distribution of trace metals (Cu, Fe, Mg, Sr, Pb, and Zn) in 196 x 339 {mu}m{sup 2} raster pattern areas (6.6 x 10{sup 4} {mu}m{sup 2}) in a deciduous tooth using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Ablated areas include prenatal and postnatal enamel, the neonatal line, the dentine-enamel junction (DEJ), dentine, and the dentine-pulp junction. Topographic variations in the surface elemental distribution of lead, zinc, strontium, and iron intensities in a deciduous tooth revealed heterogeneous distribution within and among regions. {sup 43}Ca normalized elemental intensities showed the following order: Sr>Mg>>Zn>Pb>Fe>Cu. Elevated zinc and lead levels were present in the dental pulp region and at the neonatal line. This study demonstrates the ability of LA-ICP-MS to provide unique elemental distribution information in micro spatial areas of dental hard tissues. Elemental distribution plots could be useful in decoding nutrition and pollution information embedded in their bio apatite structure. (orig.)

  19. Scalar relativistic calculations of hyperfine coupling constants using ab initio density matrix renormalization group method in combination with third-order Douglas-Kroll-Hess transformation: case studies on 4d transition metals.

    Science.gov (United States)

    Nguyen Lan, Tran; Kurashige, Yuki; Yanai, Takeshi

    2015-01-13

    We have developed a new computational scheme for high-accuracy prediction of the isotropic hyperfine coupling constant (HFCC) of heavy molecules, accounting for the high-level electron correlation effects, as well as the scalar-relativistic effects. For electron correlation, we employed the ab initio density matrix renormalization group (DMRG) method in conjunction with a complete active space model. The orbital-optimization procedure was employed to obtain the optimized orbitals required for accurately determining the isotropic HFCC. For the scalar-relativistic effects, we initially derived and implemented the Douglas-Kroll-Hess (DKH) hyperfine coupling operators up to the third order (DKH3) by using the direct transformation scheme. A set of 4d transition-metal radicals consisting of Ag atom, PdH, and RhH2 were chosen as test cases. Good agreement between the isotropic HFCC values obtained from DMRG/DKH3 and experiment was archived. Because there are no available gas-phase values for PdH and RhH2 radicals in the literature, the results from the present high-level theory may serve as benchmark data.

  20. Using coupled micropillar compression and micro-Laue diffraction to investigate deformation mechanisms in a complex metallic alloy Al{sub 13}Co{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Bhowmik, Ayan, E-mail: a.bhowmik@ic.ac.uk; Britton, T. Ben; Sernicola, Giorgio; Dye, David [Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom); Dolbnya, Igor P. [Diamond Light Source, Didcot, Oxfordshire OX11 0DE (United Kingdom); Jones, Nicholas G.; Walter, Claudia; Clegg, William J. [Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 0FS (United Kingdom); Gille, Peter [Crystallographic Section, Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Munich D-80333 (Germany); Giuliani, Finn [Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom); Department of Mechanical Engineering, Imperial College London, London SW7 2AZ (United Kingdom)

    2016-03-14

    In this study, we have used in-situ micro-Laue diffraction combined with micropillar compression of focused ion beam milled Al{sub 13}Co{sub 4} complex metallic alloy to investigate the evolution of deformation in Al{sub 13}Co{sub 4}. Streaking of the Laue spots shows that the onset of plastic flow occurs at stresses as low as 0.8 GPa, although macroscopic yield only becomes apparent at 2 GPa. The measured misorientations, obtained from peak splitting, enable the geometrically necessary dislocation density to be estimated as 1.1 × 10{sup 13 }m{sup −2}.

  1. Non normal and non quadratic anisotropic plasticity coupled with ductile damage in sheet metal forming: Application to the hydro bulging test

    International Nuclear Information System (INIS)

    Badreddine, Houssem; Saanouni, Khemaies; Dogui, Abdelwaheb

    2007-01-01

    In this work an improved material model is proposed that shows good agreement with experimental data for both hardening curves and plastic strain ratios in uniaxial and equibiaxial proportional loading paths for steel metal until the final fracture. This model is based on non associative and non normal flow rule using two different orthotropic equivalent stresses in both yield criterion and plastic potential functions. For the plastic potential the classical Hill 1948 quadratic equivalent stress is considered while for the yield criterion the Karafillis and Boyce 1993 non quadratic equivalent stress is used taking into account the non linear mixed (kinematic and isotropic) hardening. Applications are made to hydro bulging tests using both circular and elliptical dies. The results obtained with different particular cases of the model such as the normal quadratic and the non normal non quadratic cases are compared and discussed with respect to the experimental results

  2. Determination of trace metal concentrations in ginseng (Panax Quinquefolius (American)) roots for forensic comparison using Inductively Coupled Plasma Mass-Spectrometry.

    Science.gov (United States)

    Peake, Barrie M; Tong, Alfred Y C; Wells, William J; Harraway, John A; Niven, Brian E; Weege, Butch; LaFollette, Douglas J

    2015-06-01

    The trace metal content of roots of samples of the American ginseng natural herbal plant species (Panax quinquefolius) was investigated as a means of differentiating between this species grown on Wisconsin and New Zealand farms, and from Canadian and Chinese sources. ICP-MS measurements were undertaken by ashing samples of the roots and then digestion with conc. HNO3 and H2O2. There was considerable variation in the concentrations of 28 detectable elements along the length of a root, between different roots, between different farms/sources and between different countries. Statistical processing of the log-transformed concentration data was undertaken using principal component analysis (PCA) and discriminant function analysis (DFA). Although PCA showed some differentiation between samples, a much clearer discrimination of the Panax quinquefolius species of ginseng from the four countries was observed using DFA. 88% of the variation between countries could be accounted for by only using discriminant function 1 while 80% of the remaining 12% of the variation between countries is accounted for by discriminant function 2. The Fisher Classification Functions classify 98% of the 87 samples to the correct country of origin with 97% of the cross-validated cases correctly classified. The predictive ability of this DFA model was further tested by constructing 100 discriminant models each using a random selection of the data for two thirds of the 87 sampled ginseng root tops, and then using the resulting classification functions to determine correctly the country of origin of the remaining third of the cases. The mean success rate of the 100 classifications was 92%. These results suggest that measurement and statistical analysis of just the trace metal content of the roots of Panax quinquefolius promises to be an excellent predictor of the country of origin of this ginseng species. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  3. A high-throughput microdialysis-parallel solid phase extraction-inductively coupled plasma mass spectrometry hyphenated system for continuous monitoring of extracellular metal ions in living rat brain.

    Science.gov (United States)

    Su, Cheng-Kuan; Hsia, Sheng-Chieh; Sun, Yuh-Chang

    2014-01-24

    To significantly improve the temporal resolving power of in vivo trace brain metal monitoring system, in this paper we describe a novel analytical configuration combining the dual functions of online segmentation of the rat brain microdialysate and parallel solid phase extraction (SPE) of multiple segmented samples. In contrast to traditional SPE procedures, in this study the three pumped media-the buffered rat brain microdialysate, the eluent, and the air stream-were converted to a series of segmented streams through the manipulation of a flow-through stream selector. After optimizing this online automatic MD/parallel poly(vinyl chloride) SPE/inductively coupled plasma mass spectrometry hyphenated system for the analysis of ultra-trace metal ions, the sample volume of the microdialysate was set at 0.83μL, the analytical sequence was repeatable every 20s, and the detection limits were in the range 0.03-0.24μgL(-1), with spike analyses of Mn, Co, Ni, Cu, and Zn in a rat brain ECF sample agreeing well with expected values (88-107%). To further examine the system's practicability, we also performed (i) in vivo dynamic monitoring of these trace metal ions in living rat brain extracellular fluid post-probe implantation (the basal values for Mn, Co, Ni, Cu, and Zn were 1.17±0.18, 1.27±0.36, 2.46±0.62, 0.86±0.37, and 2.35±0.55μgL(-1), respectively) and (ii) real-time visualization of the physiological response to acute neural depolarization elicited upon perfusing a high-K(+) medium through the MD probe. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Application of inductively coupled plasma mass spectrometry (ICP/MS) to detection of trace elements, heavy metals and radioisotopes in scalp hair

    International Nuclear Information System (INIS)

    Ozturk, Yildirim; Benderli, Cihan

    2010-01-01

    Trace element analysis of human hair has the potential to reveal retrospective information about an individual's nutritional status and exposure. As trace elements are incorporated into the hair during the growth process, longitudinal segments of the hair may reflect the body burden during the growth period. it was evaluated the potential of human hair to indicate exposure or nutritional status over time by analysing trace element profiles in single strands of human hair. By using inductively coupled plasma mass spectrometry (ICP-MS), it was achieved profiles of 43 elements in single strands of human hair. It was shown that trace element analysis along single strands of human hair can yield information about essential and toxic elements and for some elements, can be correlated with seasonal changes in diet and exposure. The information obtained from the trace element profiles of human hair in this study substantiates the potential of hair as a biomarker

  5. Dynamics of folding: Impact of fault bend folds on earthquake cycles

    Science.gov (United States)

    Sathiakumar, S.; Barbot, S.; Hubbard, J.

    2017-12-01

    Earthquakes in subduction zones and subaerial convergent margins are some of the largest in the world. So far, forecasts of future earthquakes have primarily relied on assessing past earthquakes to look for seismic gaps and slip deficits. However, the roles of fault geometry and off-fault plasticity are typically overlooked. We use structural geology (fault-bend folding theory) to inform fault modeling in order to better understand how deformation is accommodated on the geological time scale and through the earthquake cycle. Fault bends in megathrusts, like those proposed for the Nepal Himalaya, will induce folding of the upper plate. This introduces changes in the slip rate on different fault segments, and therefore on the loading rate at the plate interface, profoundly affecting the pattern of earthquake cycles. We develop numerical simulations of slip evolution under rate-and-state friction and show that this effect introduces segmentation of the earthquake cycle. In crustal dynamics, it is challenging to describe the dynamics of fault-bend folds, because the deformation is accommodated by small amounts of slip parallel to bedding planes ("flexural slip"), localized on axial surface, i.e. folding axes pinned to fault bends. We use dislocation theory to describe the dynamics of folding along these axial surfaces, using analytic solutions that provide displacement and stress kernels to simulate the temporal evolution of folding and assess the effects of folding on earthquake cycles. Studies of the 2015 Gorkha earthquake, Nepal, have shown that fault geometry can affect earthquake segmentation. Here, we show that in addition to the fault geometry, the actual geology of the rocks in the hanging wall of the fault also affect critical parameters, including the loading rate on parts of the fault, based on fault-bend folding theory. Because loading velocity controls the recurrence time of earthquakes, these two effects together are likely to have a strong impact on the

  6. Electromagnetic Pulse Coupling Analysis of Electronic Equipment

    OpenAIRE

    Hong Lei; Qingying LI

    2017-01-01

    High-intensity nuclear explosion caused by high-altitude nuclear electromagnetic pulse through the antenna, metal cables, holes and other channels, coupled with very high energy into the electronic device, and cause serious threats. In this paper, the mechanism, waveform, coupling path and damage effect of nuclear electromagnetic pulse is analyzed, and the coupling mechanism of nuclear electromagnetic pulse is studied.

  7. Understanding the folding process of synthetic polymers by small ...

    Indian Academy of Sciences (India)

    This two-point interaction between the folding agent and the polymer backbone leads to a folding of the polymer chain, which was readily monitored by NMR titrations. The effect of various parameters, such as structures of the folding agent and polymer, and the solvent composition, on the folding propensities of the polymer ...

  8. Comparison of fault-related folding algorithms to restore a fold-and-thrust-belt

    Science.gov (United States)

    Brandes, Christian; Tanner, David

    2017-04-01

    Fault-related folding means the contemporaneous evolution of folds as a consequence of fault movement. It is a common deformation process in the upper crust that occurs worldwide in accretionary wedges, fold-and-thrust belts, and intra-plate settings, in either strike-slip, compressional, or extensional regimes. Over the last 30 years different algorithms have been developed to simulate the kinematic evolution of fault-related folds. All these models of fault-related folding include similar simplifications and limitations and use the same kinematic behaviour throughout the model (Brandes & Tanner, 2014). We used a natural example of fault-related folding from the Limón fold-and-thrust belt in eastern Costa Rica to test two different algorithms and to compare the resulting geometries. A thrust fault and its hanging-wall anticline were restored using both the trishear method (Allmendinger, 1998; Zehnder & Allmendinger, 2000) and the fault-parallel flow approach (Ziesch et al. 2014); both methods are widely used in academia and industry. The resulting hanging-wall folds above the thrust fault are restored in substantially different fashions. This is largely a function of the propagation-to-slip ratio of the thrust, which controls the geometry of the related anticline. Understanding the controlling factors for anticline evolution is important for the evaluation of potential hydrocarbon reservoirs and the characterization of fault processes. References: Allmendinger, R.W., 1998. Inverse and forward numerical modeling of trishear fault propagation folds. Tectonics, 17, 640-656. Brandes, C., Tanner, D.C. 2014. Fault-related folding: a review of kinematic models and their application. Earth Science Reviews, 138, 352-370. Zehnder, A.T., Allmendinger, R.W., 2000. Velocity field for the trishear model. Journal of Structural Geology, 22, 1009-1014. Ziesch, J., Tanner, D.C., Krawczyk, C.M. 2014. Strain associated with the fault-parallel flow algorithm during kinematic fault

  9. Exploring the "fold-in" strategy toward the construction of a highly-strained triazasumanene skeleton.

    Science.gov (United States)

    Chen, Fengkun; Tanaka, Takayuki; Osuka, Atsuhiro

    2017-02-28

    The synthesis of tribenzotriazasumanene was attempted on the basis of the "fold-in" synthesis of cyclic pyrrole trimer 5 and its analogues under oxidative and reductive conditions. While unexpectedly triply-fused product 6 was obtained in the oxidation of 5 with FeCl 3 and AgOTf, the reductive coupling of hexabromo-tri-N-methylpyrrole trimer 9 furnished partially fused product 10. These results indicate the potential of the "fold-in" strategy that gave complementary outcomes depending on the reaction conditions.

  10. Quantitative Phosphoproteome Analysis of Lysophosphatidic Acid Induced Chemotaxis applying Dual-step ¹⁸O Labeling Coupled with Immobilized Metal-ion Affinity Chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Shi-Jian; Wang, Yingchun; Jacobs, Jon M.; Qian, Weijun; Yang, Feng; Tolmachev, Aleksey V.; Du, Xiuxia; Wang, Wei; Moore, Ronald J.; Monroe, Matthew E.; Purvine, Samuel O.; Waters, Katrina M.; Heibeck, Tyler H.; Adkins, Joshua N.; Camp, David G.; Klemke, Richard L.; Smith, Richard D.

    2008-10-01

    Reversible protein phosphorylation is a central cellular regulatory mechanism in modulating protein activity and propagating signals within cellular pathways and networks. Development of more effective methods for the simultaneous identification of phosphorylation sites and quantification of temporal changes in protein phosphorylation could provide important insights into molecular signaling mechanisms in a variety of different cellular processes. Here we present an integrated quantitative phosphoproteomics approach and its applications for comparative analysis of Cos-7 cells in response to lysophosphatidic acid (LPA) gradient stimulation. The approach combines trypsin-catalyzed 16O/18O labeling plus 16O/18O-methanol esterification labeling for quantitation, a macro- Immobilized Metal-ion Affinity Chromatography trap for phosphopeptide enrichment, and a monolithic capillary column with integrated electrospray emitter. LC separation and MS/MS is followed by neutral loss-dependent MS/MS/MS for phosphopeptide identification using a linear ion trap (LTQ)-FT mass spectrometer and complementary searching algorithms for interpreting MS/MS spectra. Protein phosphorylation involved in various signaling pathways of cell migration were identified and quantified, such as mitogen-activated protein kinase 1, dual-specificity mitogen-activated protein kinase kinase 2, and dual-specificity tyrosine-phosphorylation regulated kinase 1b, and a number of Rho GTPase-activating proteins. These results demonstrate the efficiency of this quantitative phosphoproteomics approach and its application for rapid discovery of phosphorylation events associated with gradient sensing and cell chemotaxis.

  11. Analysis of metallic nanoparticles and their ionic counterparts in complex matrix by reversed-phase liquid chromatography coupled to ICP-MS.

    Science.gov (United States)

    Yang, Yuan; Luo, Li; Li, Hai-Pu; Wang, Qiang; Yang, Zhao-Guang; Qu, Zhi-Peng; Ding, Ru

    2018-05-15

    Developing quantification and characterization methodology for metallic nanoparticles (MNPs) and their ionic component in complex matrix are crucial for the evaluation of their environmental behavior and health risks to humans. In this study, reversed phase high performance liquid chromatography combined ICP-MS was established for the characterization of MNPs in complex matrix. The ionic component could be separated from NPs with the optimized parameters of aqueous mobile phase. Good linear relationship between average diameter and retention time of NPs was obtained using HPLC-ICP-MS and the size smaller than 40 nm could be determined with this method, the detected results were in accordance with TEM results. The low detection limit of AuNPs and Au(Ⅲ) (both in sub-μg/L level) showed that this method was promising for the characterization of AuNPs and Au(Ⅲ) in environmental water. The mass concentration of ionic Au(Ⅲ) in environmental water could be detected using the proposed HPLC-ICP-MS and the concentration of AuNPs was obtained by subtracting the Au(Ⅲ) concentration from the total Au (The concentration of total Au was detected by ICP-MS after microwave digestion). Furthermore this proposed HPLC-ICP-MS method and single particle-ICPMS (SP-ICP-MS) was used for the analysis of the Ag speciation in commercial antibacterial products. Copyright © 2018 Elsevier B.V. All rights reserved.

  12. Continuous syntheses of Pd@Pt and Cu@Ag core-shell nanoparticles using microwave-assisted core particle formation coupled with galvanic metal displacement.

    Science.gov (United States)

    Miyakawa, Masato; Hiyoshi, Norihito; Nishioka, Masateru; Koda, Hidekazu; Sato, Koichi; Miyazawa, Akira; Suzuki, Toshishige M

    2014-08-07

    Continuous synthesis of Pd@Pt and Cu@Ag core-shell nanoparticles was performed using flow processes including microwave-assisted Pd (or Cu) core-nanoparticle formation followed by galvanic displacement with a Pt (or Ag) shell. The core-shell structure and the nanoparticle size were confirmed using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) observation and EDS elemental mapping. The Pd@Pt nanoparticles with a particle size of 6.5 ± 0.6 nm and a Pt shell thickness of ca. 0.25 nm were synthesized with appreciably high Pd concentration (Pd 100 mM). This shell thickness corresponds to one atomic layer thickness of Pt encapsulating the Pd core metal. The particle size of core Pd was controlled by tuning the initial concentrations of Na2[PdCl4] and PVP. Core-shell Cu@Ag nanoparticles with a particle size of 90 ± 35 nm and an Ag shell thickness of ca. 3.5 nm were obtained using similar sequential reactions. Oxidation of the Cu core was suppressed by the coating of Cu nanoparticles with the Ag shell.

  13. P-channel differential multiple-time programmable memory cells by laterally coupled floating metal gate fin field-effect transistors

    Science.gov (United States)

    Wang, Tai-Min; Chien, Wei-Yu; Hsu, Chia-Ling; Lin, Chrong Jung; King, Ya-Chin

    2018-04-01

    In this paper, we present a new differential p-channel multiple-time programmable (MTP) memory cell that is fully compatible with advanced 16 nm CMOS fin field-effect transistors (FinFET) logic processes. This differential MTP cell stores complementary data in floating gates coupled by a slot contact structure, which make different read currents possible on a single cell. In nanoscale CMOS FinFET logic processes, the gate dielectric layer becomes too thin to retain charges inside floating gates for nonvolatile data storage. By using a differential architecture, the sensing window of the cell can be extended and maintained by an advanced blanket boost scheme. The charge retention problem in floating gate cells can be improved by periodic restoring lost charges when significant read window narrowing occurs. In addition to high programming efficiency, this p-channel MTP cells also exhibit good cycling endurance as well as disturbance immunity. The blanket boost scheme can remedy the charge loss problem under thin gate dielectrics.

  14. Entanglement in correlated random spin chains, RNA folding and kinetic roughening

    International Nuclear Information System (INIS)

    Rodríguez-Laguna, Javier; Santalla, Silvia N; Ramírez, Giovanni; Sierra, Germán

    2016-01-01

    Average block entanglement in the 1D XX-model with uncorrelated random couplings is known to grow as the logarithm of the block size, in similarity to conformal systems. In this work we study random spin chains whose couplings present long range correlations, generated as gaussian fields with a power-law spectral function. Ground states are always planar valence bond states, and their statistical ensembles are characterized in terms of their block entropy and their bond-length distribution, which follow power-laws. We conjecture the existence of a critical value for the spectral exponent, below which the system behavior is identical to the case of uncorrelated couplings. Above that critical value, the entanglement entropy violates the area law and grows as a power law of the block size, with an exponent which increases from zero to one. Interestingly, we show that XXZ models with positive anisotropy present the opposite behavior, and strong correlations in the couplings lead to lower entropies. Similar planar bond structures are also found in statistical models of RNA folding and kinetic roughening, and we trace an analogy between them and quantum valence bond states. Using an inverse renormalization procedure we determine the optimal spin-chain couplings which give rise to a given planar bond structure, and study the statistical properties of the couplings whose bond structures mimic those found in RNA folding. (paper)

  15. Image analysis of vocal fold histology

    Science.gov (United States)

    Reinisch, Lou; Garrett, C. Gaelyn

    2001-05-01

    To visualize the concentration gradients of collagen, elastin and ground substance in histologic sections of vocal folds, an image enhancement scheme was devised. Slides stained with Movat's solution were viewed on a light microscope. The image was digitally photographed. Using commercially available software, all pixels within a color range are selected from the mucosa presented on the image. Using the Movat's pentachrome stain, yellow to yellow-brown pixels represented mature collagen, blue to blue-green pixels represented young collagen (collagen that is not fully cross-linked) and black to dark violet pixels represented elastin. From each of the color range selections, a black and white image was created. The pixels not within the color range were black. The selected pixels within the color range were white. The image was averaged and smoothed to produce 256 levels of gray with less spatial resolution. This new grey-scale image showed the concentration gradient. These images were further enhanced with contour lines surrounding equivalent levels of gray. This technique is helpful to compare the micro-anatomy of the vocal folds. For instance, we find large concentration of the collagen deep in the mucosa and adjacent to the vocalis muscle.

  16. Numerical modeling of fold-and-thrust belts: Applications to Kuqa foreland fold belt, China

    Science.gov (United States)

    Yin, H.; Morgan, J. K.; Zhang, J.; Wang, Z.

    2009-12-01

    We constructed discrete element models to simulate the evolution of fold-and-thrust belts. The impact of rock competence and decollement strength on the geometric pattern and deformation mechanics of fold-and-thrust belts has been investigated. The models reproduced some characteristic features of fold-and-thrust belts, such as faulted detachment folds, pop-ups, far-traveled thrust sheets, passive-roof duplexes, and back thrusts. In general, deformation propagates farther above a weak decollement than above a strong decollement. Our model results confirm that fold-and-thrust belts with strong frictional decollements develop relatively steep and narrow wedges formed by closely spaced imbricate thrust slices, whereas fold belts with weak decollements form wide low-taper wedges composed of faulted detachment folds, pop-ups, and back thrusts. Far-traveled thrust sheets and passive-roof duplexes are observed in the model with a strong lower decollement and a weak upper detachment. Model results also indicate that the thickness of the weak layer is critical. If it is thick enough, it acts as a ductile layer that is able to flow under differential stress, which helps to partition deformation above and below it. The discrete element modeling results were used to interpret the evolution of Kuqa Cenozoic fold-and-thrust belt along northern Tarim basin, China. Seismic and well data show that the widely distributed Paleogene rock salt has a significant impact on the deformation in this area. Structures beneath salt are closely spaced imbricate thrust and passive-roof duplex systems. Deformation above salt propagates much farther than below the salt. Faults above salt are relatively wide spaced. A huge controversy over the Kuqa fold-and-thrust belt is whether it is thin-skinned or thick-skinned. With the insights from DEM results, we suggest that Kuqa structures are mostly thin-skinned with Paleogene salt as decollement, except for the rear part near the backstop, where the

  17. Evaluation of the use of multiple lines for determination of metals in water by inductively coupled plasma optical emission spectrometry with axial viewing

    Energy Technology Data Exchange (ETDEWEB)

    Schiavo, Daniela [Grupo de Analise Instrumental Aplicada, Departamento de Quimica, Universidade Federal de Sao Carlos, P.O. Box 676, 13565-905 Sao Carlos, SP (Brazil); Trevizan, Lilian C. [Centro de Energia Nuclear na Agricultura, Universidade de Sao Paulo, CENA/USP, Piracicaba, SP (Brazil); Pereira-Filho, Edenir R. [Grupo de Analise Instrumental Aplicada, Departamento de Quimica, Universidade Federal de Sao Carlos, P.O. Box 676, 13565-905 Sao Carlos, SP (Brazil); Nobrega, Joaquim A. [Grupo de Analise Instrumental Aplicada, Departamento de Quimica, Universidade Federal de Sao Carlos, P.O. Box 676, 13565-905 Sao Carlos, SP (Brazil)], E-mail: djan@ufscar.br

    2009-06-15

    Inductively coupled plasma optical emission spectrometers (ICP OES) allow fast simultaneous measurements of several spectral lines for multiple elements. The combination of signal intensities of two or more emission lines for each element may bring such advantages as improvement of the precision, the minimization of systematic errors caused by spectral interferences and matrix effects. In this work, signal intensities for several spectral lines were combined for the determination of Al, Cd, Co, Cr, Mn, Pb, and Zn in water. Afterwards, parameters for evaluation of the calibration model were calculated to select the combination of emission lines leading to the best accuracy (lowest values of PRESS-Predicted error sum of squares and RMSEP-Root means square error of prediction). Limits of detection (LOD) obtained using multiple lines were 7.1, 0.5, 4.4, 0.042, 3.3, 28 and 6.7 {mu}g L{sup - 1} (n = 10) for Al, Cd, Co, Cr, Mn, Pb and Zn, respectively, in the presence of concomitants. On the other hand, the LOD established for the most intense emission line were 16, 0.7, 8.4, 0.074, 23, 26 and 9.6 {mu}g L{sup - 1} (n = 10) for these same elements in the presence of concomitants. The accuracy of the developed procedure was demonstrated using water certified reference material. The use of multiple lines improved the sensitivity making feasible the determination of these analytes according to the target values required for the current environmental legislation for water samples and it was also demonstrated that measurements in multiple lines can also be employed as a tool to verify the accuracy of an analytical procedure in ICP OES.

  18. Tunable coupled surface acoustic cavities

    Science.gov (United States)

    de Lima, M. M.; Santos, P. V.; Kosevich, Yu. A.; Cantarero, A.

    2012-06-01

    We demonstrate the electric tuning of the acoustic field in acoustic microcavities (MCs) defined by a periodic arrangement of metal stripes within a surface acoustic delay line on LiNbO3 substrate. Interferometric measurements show the enhancement of the acoustic field distribution within a single MC, the presence of a "bonding" and "anti-bonding" modes for two strongly coupled MCs, as well as the positive dispersion of the "mini-bands" formed by five coupled MCs. The frequency and amplitude of the resonances can be controlled by the potential applied to the metal stripes.

  19. Improving decoy databases for protein folding algorithms

    KAUST Repository

    Lindsey, Aaron

    2014-01-01

    Copyright © 2014 ACM. Predicting protein structures and simulating protein folding are two of the most important problems in computational biology today. Simulation methods rely on a scoring function to distinguish the native structure (the most energetically stable) from non-native structures. Decoy databases are collections of non-native structures used to test and verify these functions. We present a method to evaluate and improve the quality of decoy databases by adding novel structures and removing redundant structures. We test our approach on 17 different decoy databases of varying size and type and show significant improvement across a variety of metrics. We also test our improved databases on a popular modern scoring function and show that they contain a greater number of native-like structures than the original databases, thereby producing a more rigorous database for testing scoring functions.

  20. Noise Folding in Completely Perturbed Compressed Sensing

    Directory of Open Access Journals (Sweden)

    Limin Zhou

    2016-01-01

    Full Text Available This paper first presents a new generally perturbed compressed sensing (CS model y=(A+E(x+u+e, which incorporated a general nonzero perturbation E into sensing matrix A and a noise u into signal x simultaneously based on the standard CS model y=Ax+e and is called noise folding in completely perturbed CS model. Our construction mainly will whiten the new proposed CS model and explore in restricted isometry property (RIP and coherence of the new CS model under some conditions. Finally, we use OMP to give a numerical simulation which shows that our model is feasible although the recovered value of signal is not exact compared with original signal because of measurement noise e, signal noise u, and perturbation E involved.

  1. Neutron structural biology. Beyond the folding structure

    International Nuclear Information System (INIS)

    Niimura, Nobuo

    2009-01-01

    Hydrogen atoms and water molecules around proteins and nucleic acids play a crucial role in many physiological functions. Neutron diffraction provides an experimental method of directly locating hydrogen atoms. (a) Since almost all the H atom positions can be identified experimentally, the geometrical details of certain types of H-bonds can be visualized and (b) as far as mechanistic implications are concerned, the identification of protonation and deprotonation states of certain important amino acid residues can be carried out. (c) The hydration structure around proteins and the hydration networks around DNA oligomers have been successfully characterized in several outstanding cases. These will open the new field beyond the folding structure of bio-macromolecules such as: 1) Recognition of proteins and nucleic acids through the network structure of water molecules surrounding bio-macromolecules, and 2) The nature of chemical bond in proteins and nucleic acids elucidated by the accumulation of accurate structural information of hydrogen atoms. (author)

  2. Electrotransfection of Polyamine Folded DNA Origami Structures.

    Science.gov (United States)

    Chopra, Aradhana; Krishnan, Swati; Simmel, Friedrich C

    2016-10-12

    DNA origami structures are artificial molecular nanostructures in which DNA double helices are forced into a closely packed configuration by a multitude of DNA strand crossovers. We show that three different types of origami structures (a flat sheet, a hollow tube, and a compact origami block) can be formed in magnesium-free buffer solutions containing low (origami folding is proportional to the DNA concentration. At excessive amounts, the structures aggregate and precipitate. In contrast to origami structures formed in conventional buffers, the resulting structures are stable in the presence of high electric field pulses, such as those commonly used for electrotransfection experiments. We demonstrate that spermidine-stabilized structures are stable in cell lysate and can be delivered into mammalian cells via electroporation.

  3. Microscopic Phonosurgery in Benign Vocal Fold Lesions

    Directory of Open Access Journals (Sweden)

    Sukamal Das

    2014-06-01

    Thirty out of 32 patients showed objective improvement in fibreoptic laryngoscopy post treatment. Two patients were noncompliant to voice therapy and showed recurrence of their pathologies.Mean VHI 10 score showed significant improvement from 8 in the preoperative period to 3 in the postoperative period. Conclusion : Phonosurgery is a quick and effective treatment with uncommon and transient post-operative complications. Pre and postoperative voice therapy plays an integral role in combination with phono-micro surgery enhances the outcome in patients with benign vocal fold lesions. Objective assessment of the voice pre- and postoperatively should be used consistently to evaluate the additional impact of pre- and postoperative voice therapy.

  4. On the folding of graphs-theory and application

    International Nuclear Information System (INIS)

    Nada, S.I.; Hamouda, E.H.

    2009-01-01

    In this article, we recall the definition of graph folding in the sense of El-kholy and El-Esawy [El-kholy E, El-Esawy A. Graph folding of some special graphs. J Math Stat 2005;1(1):66-70.] and study the limit of folding of some graphs. Also we define the folding number and give a formula to compute the number of folding maps f: P n → P n , where P n is a path with n edges. We also discuss application of folding from Orgami to buckling and high energy physics.

  5. Examination of the Vocal Fold Paralysis on the Fluid Dynamics of the Glottis

    Science.gov (United States)

    Sherman, Erica; Krane, Michael; Zhang, Lucy; Wei, Timothy

    2011-11-01

    This talk is coupled to the symmetric vocal fold oscillation study presented in Halvorson, et al. In this study, one of the two symmetric vocal fold models was allowed to remain rigid while the other model was driven through a normal oscillation cycle. Again, a range of reduced frequencies were studied corresponding to physiological frequencies from 100--200 Hz. Flow measurements showing jet velocity and orientation, vortex shedding as a function of time through an oscillation cycle will be presented. Experimental data has been phase averaged to highlight characteristic differences between male and female voices. Additionally, volumetric flow rate and glottal behavior will be presented to show recurring features in phonation during an oscillation cycle. An example of differences between the paralysis case and the symmetrically oscillating vocal fold case is that the Coanda effect develops much more quickly and predictably for the paralysis case. Additional comparisons between diseased and healthy conditions will be presented and discussed. Supported by the NIH.

  6. Strain Hardening and Size Effect in Five-fold Twinned Ag Nanowires.

    Science.gov (United States)

    Narayanan, Sankar; Cheng, Guangming; Zeng, Zhi; Zhu, Yong; Zhu, Ting

    2015-06-10

    Metallic nanowires usually exhibit ultrahigh strength but low tensile ductility owing to their limited strain hardening capability. Here we study the unique strain hardening behavior of the five-fold twinned Ag nanowires by nanomechanical testing and atomistic modeling. In situ tensile tests within a scanning electron microscope revealed strong strain hardening behavior of the five-fold twinned Ag nanowires. Molecular dynamics simulations showed that such strain hardening was critically controlled by twin boundaries and pre-existing defects. Strain hardening was size dependent; thinner nanowires achieved more hardening and higher ductility. The size-dependent strain hardening was found to be caused by the obstruction of surface-nucleated dislocations by twin boundaries. Our work provides mechanistic insights into enhancing the tensile ductility of metallic nanostructures by engineering the internal interfaces and defects.

  7. Glycoprotein folding and quality-control mechanisms in protein-folding diseases

    Directory of Open Access Journals (Sweden)

    Sean P. Ferris

    2014-03-01

    Full Text Available Biosynthesis of proteins – from translation to folding to export – encompasses a complex set of events that are exquisitely regulated and scrutinized to ensure the functional quality of the end products. Cells have evolved to capitalize on multiple post-translational modifications in addition to primary structure to indicate the folding status of nascent polypeptides to the chaperones and other proteins that assist in their folding and export. These modifications can also, in the case of irreversibly misfolded candidates, signal the need for dislocation and degradation. The current Review focuses on the glycoprotein quality-control (GQC system that utilizes protein N-glycosylation and N-glycan trimming to direct nascent glycopolypeptides through the folding, export and dislocation pathways in the endoplasmic reticulum (ER. A diverse set of pathological conditions rooted in defective as well as over-vigilant ER quality-control systems have been identified, underlining its importance in human health and disease. We describe the GQC pathways and highlight disease and animal models that have been instrumental in clarifying our current understanding of these processes.

  8. Multi-elemental characterization of tunnel and road dusts in Houston, Texas using dynamic reaction cell-quadrupole-inductively coupled plasma–mass spectrometry: Evidence for the release of platinum group and anthropogenic metals from motor vehicles

    International Nuclear Information System (INIS)

    Spada, Nicholas; Bozlaker, Ayse; Chellam, Shankararaman

    2012-01-01

    Highlights: ► Analytical method for PGEs, main group, transition and rare earth metals developed. ► Comprehensive characterization of road and tunnel dust samples was accomplished. ► PGEs in dusts arise from autocatalyst attrition. ► Mobile sources also contributed to Cu, Zn, Ga, As, Mo, Cd, Sn, Sb, Ba, W and Pb. ► All other elements, including rare earths arose from crustal sources. - Abstract: Platinum group elements (PGEs) including Rh, Pd, and Pt are important tracers for vehicular emissions, though their measurement is often challenging and difficult to replicate in environmental campaigns. These challenges arise from sample preparation steps required for PGE quantitation, which often cause severe isobaric interferences and spectral overlaps from polyatomic species of other anthropogenically emitted metals. Consequently, most previous road dust studies have either only quantified PGEs or included a small number of anthropogenic elements. Therefore a novel analytical method was developed to simultaneously measure PGEs, lanthanoids, transition and main group elements to comprehensively characterize the elemental composition of urban road and tunnel dusts. Dust samples collected from the vicinity of high-traffic roadways and a busy underwater tunnel restricted to single-axle (predominantly gasoline-driven) vehicles in Houston, TX were analyzed for 45 metals with the newly developed method using dynamic reaction cell-quadrupole-inductively coupled plasma–mass spectrometry (DRC-q-ICP–MS). Average Rh, Pd and Pt concentrations were 152 ± 52, 770 ± 208 and 529 ± 130 ng g −1 respectively in tunnel dusts while they varied between 6 and 8 ng g −1 , 10 and 88 ng g −1 and 35 and 131 ng g −1 in surface road dusts. Elemental ratios and enrichment factors demonstrated that PGEs in dusts originated from autocatalyst attrition/abrasion. Strong evidence is also presented for mobile source emissions of Cu, Zn, Ga, As, Mo, Cd, Sn, Sb, Ba, W and Pb. However

  9. The review on tessellation origami inspired folded structure

    Science.gov (United States)

    Chu, Chai Chen; Keong, Choong Kok

    2017-10-01

    Existence of folds enhances the load carrying capacity of a folded structure which makes it suitable to be used for application where large open space is required such as large span roof structures and façade. Folded structure is closely related to origami especially the tessellation origami. Tessellation origami provides a folded configuration with facetted surface as a result from repeated folding pattern. Besides that, tessellation origami has flexible folding mechanism that produced a variety of 3-dimensional folded configurations. Despite the direct relationship between fold in origami and folded structure, the idea of origami inspired folded structure is not properly reviewed in the relevant engineering field. Hence, this paper aims to present the current studies from related discipline which has direct relation with application of tessellation origami in folded structure. First, tessellation origami is properly introduced and defined. Then, the review covers the topic on the origami tessellation design suitable for folded structure, its modeling and simulation method, and existing studies and applications of origami as folded structure is presented. The paper also includes the discussion on the current issues related to each topic.

  10. Self-folding origami at any energy scale

    Science.gov (United States)

    Pinson, Matthew B.; Stern, Menachem; Carruthers Ferrero, Alexandra; Witten, Thomas A.; Chen, Elizabeth; Murugan, Arvind

    2017-05-01

    Programmable stiff sheets with a single low-energy folding motion have been sought in fields ranging from the ancient art of origami to modern meta-materials research. Despite such attention, only two extreme classes of crease patterns are usually studied; special Miura-Ori-based zero-energy patterns, in which crease folding requires no sheet bending, and random patterns with high-energy folding, in which the sheet bends as much as creases fold. We present a physical approach that allows systematic exploration of the entire space of crease patterns as a function of the folding energy. Consequently, we uncover statistical results in origami, finding the entropy of crease patterns of given folding energy. Notably, we identify three classes of Mountain-Valley choices that have widely varying `typical' folding energies. Our work opens up a wealth of experimentally relevant self-folding origami designs not reliant on Miura-Ori, the Kawasaki condition or any special symmetry in space.

  11. Phonosurgery of vocal fold polyps, cysts and nodules is beneficial

    DEFF Research Database (Denmark)

    Jensen, Jane Bjerg; Rasmussen, Niels

    2013-01-01

    This study reports our experience with microscopic phonosurgery (PS) of benign lesions of the vocal folds.......This study reports our experience with microscopic phonosurgery (PS) of benign lesions of the vocal folds....

  12. Determination of trace metal ions Co, Cu, Mo, Mn, Fe, Ti, V in reference river water and reference seawater samples by inductively coupled plasma emission spectrometry combined with the third phase preconcentration.

    Science.gov (United States)

    Li, X J; Schramel, P; Wang, H Z; Grill, P; Kettrup, A

    1996-08-01

    A combination of DAM-SCN(-) third phase extraction and inductively coupled plasma emission spectrometry (ICP-AES) is used for the determination of trace metal ions in a river water and a seawater reference material. An implementation of the third phase extraction prior to ICP-AES allows a preconcentration of trace elements (Co, Cu, Mn, Fe, V, Ti, Mn) by a factor ranging from 33 to 45. A complete separation of these elements is accomplished from matrices, normally affecting the excitation characteristics of ICP and suppressing the elemental signals severely. Different factors, including pH of the solutions, amounts of reagents, matrix effects, have been investigated and optimized. Under the conditions selected, the limits of determination have been in the range of 0.02 to 0.6 microg/L. The system has been successfully applied to the determination of Cu, Mn, V in the reference river water SLRS-3 and Mo in the reference seawater NASS-3. The results were in a good agreement with the certified values.

  13. Quantum oscillations in the linear chain of coupled orbits: The organic metal with two cation layers θ-(ET)4CoBr4(C6H4Cl2)

    Science.gov (United States)

    Audouard, A.; Fortin, J.-Y.; Vignolles, D.; Lyubovskii, R. B.; Drigo, L.; Duc, F.; Shilov, G. V.; Ballon, G.; Zhilyaeva, E. I.; Lyubovskaya, R. N.; Canadell, E.

    2012-03-01

    Analytical formulae for de Haas-van Alphen (dHvA) oscillations in linear chain of coupled two-dimensional (2D) orbits (Pippard's model) are derived systematically taking into account the chemical potential oscillations in magnetic field. Although corrective terms are observed, basic (α) and magnetic-breakdown-induced (β and 2β-α) orbits can be accounted for by the Lifshits-Kosevich (LK) and Falicov-Stachowiak semiclassical models in the explored field and temperature ranges. In contrast, the "forbidden orbit"β-α amplitude is described by a non-LK equation involving a product of two classical orbit amplitudes. Furthermore, strongly non-monotonic field and temperature dependence may be observed for the second harmonics of basic frequencies such as 2α and the magnetic breakdown orbit β+α, depending on the value of the spin damping factors. These features are in agreement with the dHvA oscillation spectra of the strongly 2D organic metal θ-(ET)4CoBr4(C6H4Cl2).

  14. 3D fold growth rates in transpressional tectonic settings

    Science.gov (United States)

    Frehner, Marcel

    2015-04-01

    Geological folds are inherently three-dimensional (3D) structures; hence, they also grow in 3D. In this study, fold growth in all three dimensions is quantified numerically using a finite-element algorithm for simulating deformation of Newtonian media in 3D. The presented study is an extension and generalization of the work presented in Frehner (2014), which only considered unidirectional layer-parallel compression. In contrast, the full range from strike slip settings (i.e., simple shear) to unidirectional layer-parallel compression is considered here by varying the convergence angle of the boundary conditions; hence the results are applicable to general transpressional tectonic settings. Only upright symmetrical single-layer fold structures are considered. The horizontal higher-viscous layer exhibits an initial point-like perturbation. Due to the mixed pure- and simple shear boundary conditions a mechanical buckling instability grows from this perturbation in all three dimensions, described by: Fold amplification (vertical growth): Fold amplification describes the growth from a fold shape with low limb-dip angle to a shape with higher limb-dip angle. Fold elongation (growth parallel to fold axis): Fold elongation describes the growth from a dome-shaped (3D) structure to a more cylindrical fold (2D). Sequential fold growth (growth perpendicular to fold axial plane): Sequential fold growth describes the growth of secondary (and further) folds adjacent to the initial isolated fold. The term 'lateral fold growth' is used as an umbrella term for both fold elongation and sequential fold growth. In addition, the orientation of the fold axis is tracked as a function of the convergence angle. Even though the absolute values of all three growth rates are markedly reduced with increasing simple-shear component at the boundaries, the general pattern of the quantified fold growth under the studied general-shear boundary conditions is surprisingly similar to the end

  15. TBI server: a web server for predicting ion effects in RNA folding.

    Directory of Open Access Journals (Sweden)

    Yuhong Zhu

    Full Text Available Metal ions play a critical role in the stabilization of RNA structures. Therefore, accurate prediction of the ion effects in RNA folding can have a far-reaching impact on our understanding of RNA structure and function. Multivalent ions, especially Mg²⁺, are essential for RNA tertiary structure formation. These ions can possibly become strongly correlated in the close vicinity of RNA surface. Most of the currently available software packages, which have widespread success in predicting ion effects in biomolecular systems, however, do not explicitly account for the ion correlation effect. Therefore, it is important to develop a software package/web server for the prediction of ion electrostatics in RNA folding by including ion correlation effects.The TBI web server http://rna.physics.missouri.edu/tbi_index.html provides predictions for the total electrostatic free energy, the different free energy components, and the mean number and the most probable distributions of the bound ions. A novel feature of the TBI server is its ability to account for ion correlation and ion distribution fluctuation effects.By accounting for the ion correlation and fluctuation effects, the TBI server is a unique online tool for computing ion-mediated electrostatic properties for given RNA structures. The results can provide important data for in-depth analysis for ion effects in RNA folding including the ion-dependence of folding stability, ion uptake in the folding process, and the interplay between the different energetic components.

  16. TBI server: a web server for predicting ion effects in RNA folding.

    Science.gov (United States)

    Zhu, Yuhong; He, Zhaojian; Chen, Shi-Jie

    2015-01-01

    Metal ions play a critical role in the stabilization of RNA structures. Therefore, accurate prediction of the ion effects in RNA folding can have a far-reaching impact on our understanding of RNA structure and function. Multivalent ions, especially Mg²⁺, are essential for RNA tertiary structure formation. These ions can possibly become strongly correlated in the close vicinity of RNA surface. Most of the currently available software packages, which have widespread success in predicting ion effects in biomolecular systems, however, do not explicitly account for the ion correlation effect. Therefore, it is important to develop a software package/web server for the prediction of ion electrostatics in RNA folding by including ion correlation effects. The TBI web server http://rna.physics.missouri.edu/tbi_index.html provides predictions for the total electrostatic free energy, the different free energy components, and the mean number and the most probable distributions of the bound ions. A novel feature of the TBI server is its ability to account for ion correlation and ion distribution fluctuation effects. By accounting for the ion correlation and fluctuation effects, the TBI server is a unique online tool for computing ion-mediated electrostatic properties for given RNA structures. The results can provide important data for in-depth analysis for ion effects in RNA folding including the ion-dependence of folding stability, ion uptake in the folding process, and the interplay between the different energetic components.

  17. Factors that affect coseismic folds in an overburden layer

    Science.gov (United States)

    Zeng, Shaogang; Cai, Yongen

    2018-03-01

    Coseismic folds induced by blind thrust faults have been observed in many earthquake zones, and they have received widespread attention from geologists and geophysicists. Numerous studies have been conducted regarding fold kinematics; however, few have studied fold dynamics quantitatively. In this paper, we establish a conceptual model with a thrust fault zone and tectonic stress load to study the factors that affect coseismic folds and their formation mechanisms using the finite element method. The numerical results show that the fault dip angle is a key factor that controls folding. The greater the dip angle is, the steeper the fold slope. The second most important factor is the overburden thickness. The thicker the overburden is, the more gradual the fold. In this case, folds are difficult to identify in field surveys. Therefore, if a fold can be easily identified with the naked eye, the overburden is likely shallow. The least important factors are the mechanical parameters of the overburden. The larger the Young's modulus of the overburden is, the smaller the displacement of the fold and the fold slope. Strong horizontal compression and vertical extension in the overburden near the fault zone are the main mechanisms that form coseismic folds.

  18. 76 FR 74704 - Folded Self-Mailers and Unenveloped Mailpieces

    Science.gov (United States)

    2011-12-01

    ... as an oblong. The final folded edge of an oblong folded self-mailer must be the leading (right) edge... POSTAL SERVICE 39 CFR Part 111 Folded Self-Mailers and Unenveloped Mailpieces AGENCY: Postal... self-mailers (FSM) and unenveloped mailpieces that are mailed at automation or machinable prices. To...

  19. Folds in multilayered rocks of Proterozoic age, Rajasthan, India

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Johnson and Johnson 2002 etc) shows that the fold shape modification may be brought about by buckling and flattening operating simultaneously throughout the development of fold. In the present paper a series of F1 folds devel- oped in slates with interlayered alternations with quartzite of Proterozoic age and unaffected ...

  20. Kinematics of large scale asymmetric folds and associated smaller ...

    Indian Academy of Sciences (India)

    active-hinge folding (involving lateral migration of active axial surfaces, e.g., Suppe 1983) are invoked to explain finite fold development. Any inference about fold kinematics is based on the analysis of distributions of diagnostic deformation features (Stewart and Alvarez 1991; Fischer et al. Keywords. Kinematic history ...

  1. Nomenclature proposal to describe vocal fold motion impairment

    NARCIS (Netherlands)

    Rosen, Clark A.; Mau, Ted; Remacle, Marc; Hess, Markus; Eckel, Hans E.; Young, VyVy N.; Hantzakos, Anastasios; Yung, Katherine C.; Dikkers, Frederik G.

    2016-01-01

    The terms used to describe vocal fold motion impairment are confusing and not standardized. This results in a failure to communicate accurately and to major limitations of interpreting research studies involving vocal fold impairment. We propose standard nomenclature for reporting vocal fold

  2. Nomenclature proposal to describe vocal fold motion impairment

    NARCIS (Netherlands)

    Rosen, Clark A.; Mau, Ted; Remacle, Marc; Hess, Markus; Eckel, Hans E.; Young, VyVy N.; Hantzakos, Anastasios; Yung, Katherine C.; Dikkers, Frederik G.

    The terms used to describe vocal fold motion impairment are confusing and not standardized. This results in a failure to communicate accurately and to major limitations of interpreting research studies involving vocal fold impairment. We propose standard nomenclature for reporting vocal fold

  3. α/β Hydrolase fold enzymes: the family keeps growing

    NARCIS (Netherlands)

    Nardini, Marco; Dijkstra, B W

    1999-01-01

    The alpha/beta hydrolase fold is a typical example of a tertiary fold adopted by proteins that have no obvious sequence similarity, but nevertheless, in the course of evolution, diverged from a common ancestor. Recently solved structures demonstrate a considerably increased variability in fold

  4. Probing folding free energy landscape of small proteins through ...

    Indian Academy of Sciences (India)

    Unknown

    lattice and off-lattice models of proteins have been used to study the statistical and dynamical aspects of folding.12,13 Levitt pioneered in the computational studies of protein folding using off-lattice protein models.14 A recent off-lattice model study of HP-36 based on hydrophobicity tried to correlate the folding with many ...

  5. 77 FR 74513 - Folding Gift Boxes From China

    Science.gov (United States)

    2012-12-14

    ... COMMISSION Folding Gift Boxes From China Determination On the basis of the record \\1\\ developed in the... antidumping duty order on folding gift boxes from China would be likely to lead to continuation or recurrence... Commission are contained in USITC Publication 4365 (November 2012), entitled Folding Gift Boxes from China...

  6. Kinetics of folding of the myosin rod.

    Science.gov (United States)

    Bechet, J J; Nozais, M

    1997-02-15

    The kinetics of the unfolding and refolding of the myosin rod have been studied by fluorescence and circular dichroism techniques, at different concentrations of protein and guanidine hydrochloride. The unfolding of the myosin rod was fast and at least biphasic in 2-3 M denaturant, with an initial immediate phase followed by a slower low-amplitude first-order phase. The refolding of the rod in 0.4-2 M guanidine hydrochloride was also at least biphasic; an initial immediate phase preceded a slow second-order phase. At the final denaturant concentration of 0.8 M, the amplitude of the burst phase was weakly dependent on the protein concentration and the rate constant of the refolding slow phase was optimal. These data are incorporated into a folding mechanism with at least three states. The high rates of the first steps of unfolding and refolding may be relevant for the functioning of the native myosin molecule by allowing a transient separation of the two strands of the myosin tail.

  7. Amyloid Beta Peptide Folding in Reverse Micelles.

    Science.gov (United States)

    Eskici, Gözde; Axelsen, Paul H

    2017-07-19

    Previously published experimental studies have suggested that when the 40-residue amyloid beta peptide is encapsulated in a reverse micelle, it folds into a structure that may nucleate amyloid fibril formation (Yeung, P. S.-W.; Axelsen, P. H. J. Am. Chem. Soc. 2012, 134, 6061 ). The factors that induce the formation of this structure have now been identified in a multi-microsecond simulation of the same reverse micelle system that was studied experimentally. Key features of the polypeptide-micelle interaction include the anchoring of a hydrophobic residue cluster into gaps in the reverse micelle surface, the formation of a beta turn at the anchor point that brings N- and C-terminal segments of the polypeptide into proximity, high ionic strength that promotes intramolecular hydrogen bond formation, and deformation of the reverse micelle surface to facilitate interactions with the surface along the entire length of the polypeptide. Together, these features cause the simulation-derived vibrational spectrum to red shift in a manner that reproduces the red-shift previously reported experimentally. On the basis of these findings, a new mechanism is proposed whereby membranes nucleate fibril formation and facilitate the in-register alignment of polypeptide strands that is characteristic of amyloid fibrils.

  8. Hydrophobic-hydrophilic forces in protein folding.

    Science.gov (United States)

    Durell, Stewart R; Ben-Naim, Arieh

    2017-08-01

    The process of protein folding is obviously driven by forces exerted on the atoms of the amino-acid chain. These forces arise from interactions with other parts of the protein itself (direct forces), as well as from interactions with the solvent (solvent-induced forces). We present a statistical-mechanical formalism that describes both these direct and indirect, solvent-induced thermodynamic forces on groups of the protein. We focus on 2 kinds of protein groups, commonly referred to as hydrophobic and hydrophilic. Analysis of this result leads to the conclusion that the forces on hydrophilic groups are in general stronger than on hydrophobic groups. This is then tested and verified by a series of molecular dynamics simulations, examining both hydrophobic alkanes of different sizes and hydrophilic moieties represented by polar-neutral hydroxyl groups. The magnitude of the force on assemblies of hydrophilic groups is dependent on their relative orientation: with 2 to 4 times larger forces on groups that are able to form one or more direct hydrogen bonds. © 2017 Wiley Periodicals, Inc.

  9. Folding very short peptides using molecular dynamics.

    Directory of Open Access Journals (Sweden)

    Bosco K Ho

    2006-04-01

    Full Text Available Peptides often have conformational preferences. We simulated 133 peptide 8-mer fragments from six different proteins, sampled by replica-exchange molecular dynamics using Amber7 with a GB/SA (generalized-Born/solvent-accessible electrostatic approximation to water implicit solvent. We found that 85 of the peptides have no preferred structure, while 48 of them converge to a preferred structure. In 85% of the converged cases (41 peptides, the structures found by the simulations bear some resemblance to their native structures, based on a coarse-grained backbone description. In particular, all seven of the beta hairpins in the native structures contain a fragment in the turn that is highly structured. In the eight cases where the bioinformatics-based I-sites library picks out native-like structures, the present simulations are largely in agreement. Such physics-based modeling may be useful for identifying early nuclei in folding kinetics and for assisting in protein-structure prediction methods that utilize the assembly of peptide fragments.

  10. Structured and disordered facets of the GPCR fold.

    Science.gov (United States)

    Venkatakrishnan, A J; Flock, Tilman; Prado, Daniel Estévez; Oates, Matt E; Gough, Julian; Madan Babu, M

    2014-08-01

    The seven-transmembrane (7TM) helix fold of G-protein coupled receptors (GPCRs) has been adapted for a wide variety of physiologically important signaling functions. Here, we discuss the diversity in the structured and disordered regions of GPCRs based on the recently published crystal structures and sequence analysis of all human GPCRs. A comparison of the structures of rhodopsin-like receptors (class A), secretin-like receptors (class B), metabotropic receptors (class C) and frizzled receptors (class F) shows that the relative arrangement of the transmembrane helices is conserved across all four GPCR classes although individual receptors can be activated by ligand binding at varying positions within and around the transmembrane helical bundle. A systematic analysis of GPCR sequences reveals the presence of disordered segments in the cytoplasmic side, abundant post-translational modification sites, evidence for alternative splicing and several putative linear peptide motifs that have the potential to mediate interactions with cytosolic proteins. While the structured regions permit the receptor to bind diverse ligands, the disordered regions appear to have an underappreciated role in modulating downstream signaling in response to the cellular state. An integrated paradigm combining the knowledge of structured and disordered regions is imperative for gaining a holistic understanding of the GPCR (un)structure-function relationship. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Folding of polymer chains with short-range binormal interactions

    International Nuclear Information System (INIS)

    Craig, A; Terentjev, E M

    2006-01-01

    We study the structure of chains which have anisotropic short-range contact interactions that depend on the alignment of the binormal vectors of chain segments. This represents a crude model of hydrogen bonding or 'stacking' interactions out of the plane of curvature. The polymers are treated as ribbon-like semi-flexible chains, where the plane of the ribbon is determined by the local binormal. We show that with dipole-dipole interactions between the binormals of contacting chain segments, mean-field theory predicts a first-order transition to a binormally aligned state. We describe the onset of this transition as a function of the temperature-dependent parameters that govern the chain stiffness and the strength of the binormal interaction, as well as the binormal alignment's coupling to chain collapse. We also examine a metastable state governing the folding kinetics. Finally, we discuss the possible mesoscopic structure of the aligned phase, and application of our model to secondary structure motifs like β-sheets and α-helices, as well as composite structures like β-(amyloid) fibrils

  12. Responsive envelope tessellation and stochastic rotation of 4-fold penttiles

    Directory of Open Access Journals (Sweden)

    Sambit Datta

    2014-06-01

    Full Text Available This paper reports on the design and control of a responsive envelope based on the rotation of tessellated components. The study investigates responsive and dynamic approaches for building facades and envelopes to regulate solar shading, light control, views and thermal gain within the building. It is well known that near real-time visual output from computational simulation can significantly impact the prediction of dynamic building-environment interactions and lead to the development of smart, adaptable, net zero energy buildings. To address these motivations, this paper reports the development of an experimental simulation of a responsive envelope based on using a 4-fold penttile scheme. The simulation is developed using a novel pentagonal approach involving component (tile design, tessellation and control methods. The paper further elaborates on the geometry and control aspects of the facade subdivision and presents the results of applying this tessellation geometry to a building envelope shading study based on facade components with rotation. Finally, it tests the “responsiveness” to multiple performance metrics by applying a non-deterministic exploration method for the stochastic rotation of individual panels. The sophisticated evaluation of alternative envelope configurations for a set of performance criteria require a tighter computational coupling between modelling and control of dynamic geometry.

  13. Metallic elements fractionation in municipal solid waste incineration residues

    Science.gov (United States)

    Kowalski, Piotr R.; Kasina, Monika; Michalik, Marek

    2016-04-01

    Municipal solid waste incineration (MSWI) residues are represented by three main materials: bottom ash, fly ash and air pollution control (APC) residues. Among them ˜80 wt% is bottom ash. All of that materials are products of high temperature (>1000° C) treatment of waste. Incineration process allows to obtain significant reduction of waste mass (up to 70%) and volume (up to 90%) what is commonly used in waste management to reduce the amount need to be landfilled or managed in other way. Incineration promote accumulation non-combustible fraction of waste, which part are metallic elements. That type of concentration is object of concerns about the incineration residues impact on the environment and also gives the possibility of attempts to recover them. Metallic elements are not equally distributed among the materials. Several factors influence the process: melting points, volatility and place and forms of metallic occurrence in the incinerated waste. To investigate metallic elements distribution in MSWI residues samples from one of the biggest MSW incineration plant in Poland were collected in 2015. Chemical analysis with emphasis on the metallic elements content were performed using inductively coupled plasma optical emission (ICP-OES) and mass spectrometry (ICP-MS). The bottom ash was a SiO2-CaO-Al2O3-Fe2O3-Na2O rich material, whereas fly ash and APC residues were mostly composed of CaO and SiO2. All of the materials were rich in amorphous phase occurring together with various, mostly silicate crystalline phases. In a mass of bottom ash 11 wt% were metallic elements but also in ashes 8.5 wt% (fly ash) and ˜4.5 wt% (APC residues) of them were present. Among the metallic elements equal distribution between bottom and fly ash was observed for Al (˜3.85 wt%), Mn (770 ppm) and Ni (˜65 ppm). In bottom ash Fe (5.5 wt%), Cr (590 ppm) and Cu (1250 ppm) were concentrated. These values in comparison to fly ash were 5-fold higher for Fe, 3-fold for Cu and 1.5-fold for

  14. FUNCTIONALIZED CALIXSPHERANDS - SYNTHESIS AND PEPTIDE COUPLING

    NARCIS (Netherlands)

    BAKKER, WII; HAAS, M; DENHERTOG, HJ; VERBOOM, W; DEZEEUW, D; BRUINS, AP; REINHOUDT, DN

    1994-01-01

    Calixspherands, like 1, form kinetically stable complexes with alkali metal cations. For practical in vivo applications coupling of these complexes with carrier molecules is mandatory, Therefore, a general method for the synthesis of functionalized calixspherand 17 was developed starting from

  15. Steady-State Spectroscopic Analysis of Proton-Dependent Electron Transfer on Pyrazine-Appended Metal Dithiolenes [Ni(pdt)2], [Pd(pdt)2], and [Pt(pdt)2] (pdt = 2,3-Pyrazinedithiol).

    Science.gov (United States)

    Kennedy, Steven R; Kozar, Morgan N; Yennawar, Hemant P; Lear, Benjamin J

    2016-09-06

    We report the structural, electronic, and acid/base properties of a series of ML2 metal dithiolene complexes, where M = Ni, Pd, Pt and L = 2,3-pyrazinedithiol. These complexes are non-innocent and possess strong electronic coupling between ligands across the metal center. The electronic coupling can be readily quantified in the monoanionic mixed valence state using Marcus-Hush theory. Analysis of the intervalence charge transfer (IVCT) band reveals that that electronic coupling in the mixed valence state is 5800, 4500, and 5700 cm(-1) for the Ni, Pd, and Pt complexes, respectively. We then focus on their response to acid titration in the mixed valence state, which generates the asymmetrically protonated mixed valence mixed protonated state. For all three complexes, protonation results in severe attenuation of the electronic coupling, as measured by the IVCT band. We find nearly 5-fold decreases in electronic coupling for both Ni and Pt, while, for the Pd complex, the electronic coupling is reduced to the point that the IVCT band is no longer observable. We ascribe the reduction in electronic coupling to charge pinning induced by asymmetric protonation. The more severe reduction in coupling for the Pd complex is a result of greater energetic mismatch between ligand and metal orbitals, reflected in the smaller electronic coupling for the pure mixed valence state. This work demonstrates that the bridging metal center can be used to tune the electronic coupling in both the mixed valence and mixed valence mixed protonated states, as well as the magnitude of change of the electronic coupling that accompanies changes in protonation state.

  16. Design Procedure for Compact Folded Waveguide Filters

    DEFF Research Database (Denmark)

    Dong, Yunfeng; Johansen, Tom Keinicke; Zhurbenko, Vitaliy

    Waveguide filters are widely used in communication systems due to low losses and high power handling capabilities. One drawback of the conventional waveguide filters is their large size, especially for low-frequency and high-order realizations. It has been shown that the footprint of conventional....... The insertion loss in the pass-band (1.54 GHz – 1.56 GHz) is specified to be less than 1 dB while the return loss should be more than 18 dB. The isolation in the rejection-band (1.58 GHz – 1.60 GHz) is required to be more than 45 dB. The coupling matrix synthesis is introduced first and a two-layer realization...

  17. Perovskite catalysts for oxidative coupling

    Science.gov (United States)

    Campbell, Kenneth D.

    1991-01-01

    Perovskites of the structure A.sub.2 B.sub.2 C.sub.3 O.sub.10 are useful as catalysts for the oxidative coupling of lower alkane to heavier hydrocarbons. A is alkali metal; B is lanthanide or lanthanum, cerium, neodymium, samarium, praseodymium, gadolinium or dysprosium; and C is titanium.

  18. Cricothyroid muscle dysfunction impairs vocal fold vibration in unilateral vocal fold paralysis.

    Science.gov (United States)

    Pei, Yu-Cheng; Fang, Tuan-Jen; Li, Hsueh-Yu; Wong, Alice M K

    2014-01-01

    The relevance of the cricothyroid (CT) muscle in patients with unilateral vocal fold paralysis (UVFP) remains controversial. To clarify the functional significance of the CT muscle in patients with UVFP, the confounding effect of the severity of recurrent laryngeal nerve injury should be taken into consideration. In the present study, quantitative laryngeal electromyography (LEMG) was used to measure the severity of paralysis of the thyroarytenoid-lateral cricoarytenoid (TA-LCA) muscle complex to allow the functional contribution of the CT muscle to be determined. Cross-sectional study performed in an otolaryngology outpatient clinic. Thirty-one patients with a main diagnosis of UVFP were recruited. The main outcome measures included LEMG examination, quantitative LEMG analysis of the TA-LCA muscle complex, UVFP-related quality-of-life questionnaire (Voice Outcome Survey [VOS]), voice acoustics analysis, videolaryngostroboscopy, and general quality-of-life questionnaire (Short Form-36 Health Survey [SF-36]) assessments. The vocal cord position did not differ between patients with and without CT muscle impairment. Patients with both TA-LCA and CT paralysis showed poorer vocal fold vibration (P = .048) and higher fundamental frequency (P = .02), and the VOS and SF-36 were both poorer compared with patients with only TA-LCA paralysis. Although the vocal cord position was not influenced by CT muscle function, coexisting CT muscle paralysis may damage the voice by impairing vocal fold vibration in UVFP patients. © 2013 The American Laryngological, Rhinological and Otological Society, Inc.

  19. Comparison of metal ion concentrations and implant survival after total hip arthroplasty with metal-on-metal versus metal-on-polyethylene articulations.

    Science.gov (United States)

    Dahlstrand, Henrik; Stark, André; Wick, Marius C; Anissian, Lucas; Hailer, Nils P; Weiss, Rüdiger J

    2017-10-01

    Background and purpose - Large metal-on-metal (MoM) articulations are associated with metal wear and corrosion, leading to increased metal ion concentrations and unacceptable revision rates. There are few comparative studies of 28-mm MoM articulations with conventional metal-on-polyethylene (MoP) couplings. We present a long-term follow-up of a randomized controlled trial comparing MoM versus MoP 28-mm articulations, focused on metal ions and implant survival. Patients and methods - 85 patients with a mean age of 65 years at surgery were randomized to a MoM (Metasul) or a MoP (Protasul) bearing. After 16 years, 38 patients had died and 4 had undergone revision surgery. 13 patients were unavailable for clinical follow-up, leaving 30 patients (n = 14 MoM and n = 16 MoP) for analysis of metal ion concentrations and clinical outcome. Results - 15-year implant survival was similar in both groups (MoM 96% [95% CI 88-100] versus MoP 97% [95% CI 91-100]). The mean serum cobalt concentration was 4-fold higher in the MoM (1.5 μg/L) compared with the MoP cohort (0.4 μg/L, p concentration was double in the MoM (2.2 μg/L) compared with the MoP cohort (1.0 μg/L, p = 0.05). Mean creatinine levels were similar in both groups (MoM 93 μmol/L versus MoP 92 μmol/L). Harris hip scores differed only marginally between the MoM and MoP cohorts. Interpretation - This is the longest follow-up of a randomized trial on 28-mm MoM articulations, and although implant survival in the 2 groups was similar, metal ion concentrations remained elevated in the MoM cohort even in the long term.

  20. Protein-Folding Landscapes in Multi-Chain Systems

    Energy Technology Data Exchange (ETDEWEB)

    Cellmer, Troy; Bratko, Dusan; Prausnitz, John M.; Blanch, Harvey

    2005-06-20

    Computational studies of proteins have significantly improved our understanding of protein folding. These studies are normally carried out using chains in isolation. However, in many systems of practical interest, proteins fold in the presence of other molecules. To obtain insight into folding in such situations, we compare the thermodynamics of folding for a Miyazawa-Jernigan model 64-mer in isolation to results obtained in the presence of additional chains. The melting temperature falls as the chain concentration increases. In multi-chain systems, free-energy landscapes for folding show an increased preference for misfolded states. Misfolding is accompanied by an increase in inter-protein interactions; however, near the folding temperature, the transition from folded chains to misfolded and associated chains isentropically driven. A majority of the most probable inter-protein contacts are also native contacts, suggesting that native topology plays a role in early stages of aggregation.

  1. Exchange coupling in transition-metal ferromagnets

    Czech Academy of Sciences Publication Activity Database

    Frota-Pessoa, S.; Muniz, R. B.; Kudrnovský, Josef

    2000-01-01

    Roč. 62, č. 9 (2000), s. 5293-5296 ISSN 0163-1829 R&D Projects: GA AV ČR IAA1010829 Institutional research plan: CEZ:AV0Z1010914 Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.065, year: 2000

  2. Metal-organic framework MIL-101 as sorbent based on double-pumps controlled on-line solid-phase extraction coupled with high-performance liquid chromatography for the determination of flavonoids in environmental water samples.

    Science.gov (United States)

    Liu, Yue; Hu, Jia; Li, Yan; Li, Xiao-Shuang; Wang, Zhong-Liang

    2016-10-01

    A novel method with high sensitivity for the rapid determination of chrysin, apigenin and luteolin in environment water samples was developed by double-pumps controlled on-line solid-phase extraction (SPE) coupled with high-performance liquid chromatography (HPLC). In the developed technique, metal organic framework MIL-101 was synthesized and applied as a sorbent for SPE. The as-synthesized MIL-101 was characterized by scanning electron microscope, X-ray diffraction spectrometry, thermal gravimetric analysis and micropore physisorption analysis. The MIL-101 behaved as a fast kinetics in the adsorption of chrysin, apigenin and luteolin. On-line SPE of chrysin, apigenin and luteolin was processed by loading a sample solution at a flow rate of 1.0 mL/min for 10 min. The extracted analytes were subsequently eluted into a ZORBAX Bonus-RP analytical column (25 cm long × 4.6 mm i.d.) for HPLC separation under isocratic condition with a mobile phase (MeOH: ACN: 0.02 M H 3 PO 4 = 35:35:30) at a flow rate of 1.0 mL/min. Experimental conditions, including ionic strength, sample pH, sample loading rates, sample loading time and desorption analytes time, were further optimized to obtain efficient preconcentration and high-precision determination of the analytes mentioned above. The method achieved the merits of simplicity, rapidity, sensitivity, wide linear range and high sample throughput. The possible mechanism for the adsorption of flavonoids on MIL-101 was proposed. The developed method has been applied to determine trace chrysin, apigenin and luteolin in a variety of environmental water samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Analysis of metals and phosphorus in biodiesel B100 from different feedstock using a Flow Blurring® multinebulizer in inductively coupled plasma-optical emission spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Avila Orozco, Francisco D. [Lab. FIA, Sección Química Analítica, INQUISUR (UNS-CONICET), Universidad Nacional del Sur, Avenida Alem 1253, B8000CPB, Bahía Blanca (Argentina); Kovachev, Nikolay; Aguirre Pastor, Miguel Ángel [Dpto. Química Analítica, Nutrición y Bromatología e Instituto Universitario de Materiales, Facultad de Ciencias, Universidad de Alicante, Apdo. 99, Alicante (Spain); Domini, Claudia E.; Fernández Band, Beatriz S. [Lab. FIA, Sección Química Analítica, INQUISUR (UNS-CONICET), Universidad Nacional del Sur, Avenida Alem 1253, B8000CPB, Bahía Blanca (Argentina); Canals Hernández, Antonio, E-mail: a.canals@ua.es [Dpto. Química Analítica, Nutrición y Bromatología e Instituto Universitario de Materiales, Facultad de Ciencias, Universidad de Alicante, Apdo. 99, Alicante (Spain)

    2014-05-01

    Highlights: • The elemental analysis of biodiesel by the proposed method is simple and fast. • Two-nozzles Flow Blurring® nebulizer allow to reduce the spectral interferences. • Two-nozzles Flow Blurring® nebulizer avoid the formation of carbon deposits. • The analysis may be carried out without any sample pretreatment. Abstract: A simple and fast method for determining the content of Na, K, Ca, Mg, P, and 20 heavy metals in biodiesel samples with inductively coupled plasma optical emission spectrometry (ICP OES) using a two-nozzle Flow Blurring® multinebulizer prototype and on-line internal standard calibration, are proposed. The biodiesel samples were produced from different feedstock such as sunflower, corn, soybean and grape seed oils, via a base catalyst transesterification. The analysis was carried out without any sample pretreatment. The standards and samples were introduced through one of the multinebulizer nozzles, while the aqueous solution containing yttrium as an internal standard was introduced through the second nozzle. Thus, the spectral interferences were compensated and the formation of carbon deposits on the ICP torch was prevented. The determination coefficients (R²) were greater than 0.99 for the studied analytes, in the range 0.21–14.75 mg kg⁻¹. Short-term and long-term precisions were estimated as relative standard deviation. These were acceptable, their values being lower than 10%. The LOQ for major components such as Ca, K, Mg, Na, and P, were within a range between 4.9 ng g⁻¹ for Mg (279.553 nm) and 531.1 ng g⁻¹ for Na (588.995 nm), and for the other 20 minor components they were within a range between 1.1 ng g⁻¹ for Ba (455.403 nm) and 2913.9 ng g⁻¹ for Pb (220.353 nm). Recovery values ranged between 95% and 106%.

  4. Irregular vocal fold dynamics incited by asymmetric fluid loading in a model of recurrent laryngeal nerve paralysis

    Science.gov (United States)

    Sommer, David; Erath, Byron D.; Zanartu, Matias; Peterson, Sean D.

    2011-11-01

    Voiced speech is produced by dynamic fluid-structure interactions in the larynx. Traditionally, reduced order models of speech have relied upon simplified inviscid flow solvers to prescribe the fluid loadings that drive vocal fold motion, neglecting viscous flow effects that occur naturally in voiced speech. Viscous phenomena, such as skewing of the intraglottal jet, have the most pronounced effect on voiced speech in cases of vocal fold paralysis where one vocal fold loses some, or all, muscular control. The impact of asymmetric intraglottal flow in pathological speech is captured in a reduced order two-mass model of speech by coupling a boundary-layer estimation of the asymmetric pressures with asymmetric tissue parameters that are representative of recurrent laryngeal nerve paralysis. Nonlinear analysis identifies the emergence of irregular and chaotic vocal fold dynamics at values representative of pathological speech conditions.

  5. A Folded Excited State of Ligand-Free Nuclear Coactivator Binding Domain (NCBD) Underlies Plasticity in Ligand Recognition

    DEFF Research Database (Denmark)

    Kjaergaard, Magnus; Andersen, Lisbeth; Nielsen, Lau Dalby

    2013-01-01

    Intrinsically disordered proteins are renowned for their structural plasticity when they undergo coupled folding and binding to partner proteins. The nuclear coactivator binding domain of CBP is a remarkable example of this adaptability as it folds into two different conformations depending...... experience conformational exchange. The dispersion data can be described by a global two-state exchange process between a ground state and an excited state populated to 8%. The three helices are still folded in the excited state but have a different packing from the ground state; the contact between helices...... with that of NCBD in complex with the ligand IRF-3. The energy landscape of this domain is thus proposed to resemble the fold-switching proteins that have two coexisting native states, which may serve as a starting point for binding via conformational selection....

  6. Can Local Probes Go Global? A Joint Experiment-Simulation Analysis of λ(6-85) Folding.

    Science.gov (United States)

    Sukenik, Shahar; Pogorelov, Taras V; Gruebele, Martin

    2016-06-02

    The process of protein folding is known to involve global motions in a cooperative affair; the structure of most of the protein sequences is gained or lost over a narrow range of temperature, denaturant, or pressure perturbations. At the same time, recent simulations and experiments reveal a complex structural landscape with a rich set of local motions and conformational changes. We couple experimental kinetic and thermodynamic measurements with specifically tailored analysis of simulation data to isolate local versus global folding probes. We find that local probes exhibit lower melting temperatures, smaller surface area changes, and faster kinetics compared to global ones. We also see that certain local probes of folding match the global behavior more closely than others. Our work highlights the importance of using multiple probes to fully characterize protein folding dynamics by theory and experiment.

  7. Metal-metal-hofteproteser

    DEFF Research Database (Denmark)

    Ulrich, Michael; Overgaard, Søren; Penny, Jeannette

    2014-01-01

    In Denmark 4,456 metal-on-metal (MoM) hip prostheses have been implanted. Evidence demonstrates that some patients develope adverse biological reactions causing failures of MoM hip arthroplasty. Some reactions might be systemic. Failure rates are associated with the type and the design of the Mo...

  8. Supramolecular Nanoparticles via Single-Chain Folding Driven by Ferrous Ions.

    Science.gov (United States)

    Wang, Fei; Pu, Hongting; Jin, Ming; Wan, Decheng

    2016-02-01

    Single-chain nanoparticles can be obtained via single-chain folding assisted by intramolecular crosslinking reversibly or irreversibly. Single-chain folding is also an efficient route to simulate biomacromolecules. In present study, poly(N-hydroxyethylacrylamide-co-4'-(propoxy urethane ethyl acrylate)-2,2':6',2''-terpyridine) (P(HEAm-co-EMA-Tpy)) is synthesized via reversible addition fragmentation chain transfer polymerization. Single-chain folding and intramolecular crosslinking of P(HEAm-co-EMA-Tpy) are achieved via metal coordination chemistry. The intramolecular interaction is characterized on ultraviolet/visible spectrophotometer (UV-vis spectroscopy), proton nuclear magnetic resonance ((1)H NMR), and differential scanning calorimetry (DSC). The supramolecular crosslinking mediated by Fe(2+) plays an important role in the intramolecular collapsing of the single-chain and the formation of the nanoparticles. The size and morphology of the nanoparticles can be controlled reversibly via metal coordination chemistry, which can be characterized by dynamic light scattering (DLS), transmission electron microscope (TEM), and atomic force microscope (AFM). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Restrictions to protein folding determined by the protein size.

    Science.gov (United States)

    Finkelstein, Alexei V; Bogatyreva, Natalya S; Garbuzynskiy, Sergiy O

    2013-06-27

    Experimentally measured rates of spontaneous folding of single-domain globular proteins range from microseconds to hours: the difference (11 orders of magnitude!) is akin to the difference between the life span of a mosquito and the age of the Universe. We show that physical theory with biological constraints outlines the possible range of folding rates for single-domain globular proteins of various size and stability, and that the experimentally measured folding rates fall within this narrow "golden triangle" built without any adjustable parameters, filling it almost completely. This "golden triangle" also successfully predicts the maximal allowed size of the "foldable" protein domains, as well as the maximal size of protein domains that fold under solely thermodynamic (rather than kinetic) control. In conclusion, we give a phenomenological formula for dependence of the folding rate on the size, shape and stability of the protein fold. Copyright © 2013 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  10. Cotranslational Protein Folding inside the Ribosome Exit Tunnel

    Directory of Open Access Journals (Sweden)

    Ola B. Nilsson

    2015-09-01

    Full Text Available At what point during translation do proteins fold? It is well established that proteins can fold cotranslationally outside the ribosome exit tunnel, whereas studies of folding inside the exit tunnel have so far detected only the formation of helical secondary structure and collapsed or partially structured folding intermediates. Here, using a combination of cotranslational nascent chain force measurements, inter-subunit fluorescence resonance energy transfer studies on single translating ribosomes, molecular dynamics simulations, and cryoelectron microscopy, we show that a small zinc-finger domain protein can fold deep inside the vestibule of the ribosome exit tunnel. Thus, for small protein domains, the ribosome itself can provide the kind of sheltered folding environment that chaperones provide for larger proteins.

  11. Metallated metal-organic frameworks

    Energy Technology Data Exchange (ETDEWEB)

    Bury, Wojciech; Farha, Omar K.; Hupp, Joseph T.; Mondloch, Joseph E.

    2017-02-07

    Porous metal-organic frameworks (MOFs) and metallated porous MOFs are provided. Also provided are methods of metallating porous MOFs using atomic layer deposition and methods of using the metallated MOFs as catalysts and in remediation applications.

  12. Metallated metal-organic frameworks

    Energy Technology Data Exchange (ETDEWEB)

    Bury, Wojciech; Farha, Omar K.; Hupp, Joseph T.; Mondloch, Joseph E.

    2017-08-22

    Porous metal-organic frameworks (MOFs) and metallated porous MOFs are provided. Also provided are methods of metallating porous MOFs using atomic layer deposition and methods of using the metallated MOFs as catalysts and in remediation applications.

  13. The Complex Kinetics of Protein Folding in Wide Temperature Ranges

    OpenAIRE

    Wang, Jin

    2004-01-01

    The complex protein folding kinetics in wide temperature ranges is studied through diffusive dynamics on the underlying energy landscape. The well-known kinetic chevron rollover behavior is recovered from the mean first passage time, with the U-shape dependence on temperature. The fastest folding temperature T0 is found to be smaller than the folding transition temperature Tf. We found that the fluctuations of the kinetics through the distribution of first passage time show rather universal b...

  14. Iterative Controller Tuning for Process with Fold Bifurcations

    DEFF Research Database (Denmark)

    Huusom, Jakob Kjøbsted; Poulsen, Niels Kjølstad; Jørgensen, Sten Bay

    2007-01-01

    Processes involving fold bifurcation are notoriously difficult to control in the vicinity of the fold where most often optimal productivity is achieved . In cases with limited process insight a model based control synthesis is not possible. This paper uses a data driven approach with an improved...... version of iterative feedback tuning to optimizing a closed loop performance criterion, as a systematic tool for tuning process with fold bifurcations....

  15. Performance of metallic fuels in liquid-metal fast reactors

    International Nuclear Information System (INIS)

    Seidel, B.R.; Walters, L.C.; Kittel, J.H.

    1984-01-01

    Interest in metallic fuels for liquid-metal fast reactors has come full circle. Metallic fuels are once again a viable alternative for fast reactors because reactor outlet temperature of interest to industry are well within the range where metallic fuels have demonstrated high burnup and reliable performance. In addition, metallic fuel is very tolerant of off-normal events of its high thermal conductivity and fuel behavior. Futhermore, metallic fuels lend themselves to compact and simplified reprocessing and refabrication technologies, a key feature in a new concept for deployment of fast reactors called the Integral Fast Reactor (IFR). The IFR concept is a metallic-fueled pool reactor(s) coupled to an integral-remote reprocessing and fabrication facility. The purpose of this paper is to review recent metallic fuel performance, much of which was tested and proven during the twenty years of EBR-II operation

  16. Origin of 6-fold coordinated aluminum at (010-type pyrophyllite edges

    Directory of Open Access Journals (Sweden)

    M. Okumura

    2017-05-01

    Full Text Available To better understand the aqueous chemical reactivity of clay mineral edges we explored the relationships between hydration and the structure of (010-type edges of pyrophyllite. In particular, we used density functional theory and the quantum theory of atoms in molecules to evaluate the stability of 6-fold coordinated hydrated aluminum at the edge in terms of the electron density distribution. Geometrical optimization revealed an intra-edge hydrogen bond network between aluminol hydroxyls and water ligands completing the aluminum coordination shell. From the electron density isosurfaces one water ligand is not covalently bonded to aluminum. Bader charge analysis revealed that OH2 ligands have small negative charge. In addition, it is also found that the charge of the 6-fold coordinated aluminum is larger than one of the 5-fold aluminum. From these results, the charging of the OH2 ligands is interpreted as charge transfer originated from the formation of the hydrogen bond network and not from Al-OH2 interaction per se. This suggests that the weakly bound water ligand in question, and more generally 6-fold hydrated edge Al coordination, is stabilized primarily by the hydrogen bond network which in turn leads to weak ionic attraction to the aluminum center itself. The finding highlights the importance of cooperative effects between solvent structure and the coordination of metal cations exposed at clay mineral edges.

  17. Theory of hydrogen chemisorption on metals

    International Nuclear Information System (INIS)

    Brenig, W.

    1975-01-01

    A theory of hydrogen chemisorption on metals is presented. Green's function is derived taking into account the coupling strength between metal and chemisorbed atom and the strength of the interatomic Coulomb repulsion, allowing the calculation of the local density of states at the adatom, especially for the limiting cases of strong and weak coupling

  18. Folding System for the Clothes by a Robot and Tools

    OpenAIRE

    大澤, 文明; 関, 啓明; 神谷, 好承

    2004-01-01

    The works of a home robot has the laundering. The purpose of this study is to find a means of folding of the clothes and store the clothes in a drawer by a home robot. Because the shape of cloth tends to change in various ways depending on the situation, it is difficult for robot hands to fold the clothes. In this paper, we propose a realistic folding system for the clothes by a robot and tools. The function of a tool is folding the clothes in half by inserting the clothes using two plates. T...

  19. Specific features of vocal fold paralysis in functional computed tomography

    International Nuclear Information System (INIS)

    Laskowska, K.; Mackiewicz-Nartowicz, H.; Serafin, Z.; Nawrocka, E.

    2008-01-01

    Vocal fold paralysis is usually recognized in laryngological examination, and detailed vocal fold function may be established based on laryngovideostroboscopy. Additional imaging should exclude any morphological causes of the paresis, which should be treated pharmacologically or surgically. The aim of this paper was to analyze the computed tomography (CT) images of the larynx in patients with unilateral vocal fold paralysis. CT examinations of the larynx were performed in 10 patients with clinically defined unilateral vocal fold paralysis. The examinations consisted of unenhanced acquisition and enhanced 3-phased acquisition: during free breathing, Valsalva maneuver, and phonation. The analysis included the following morphologic features of the paresis.the deepened epiglottic vallecula, the deepened piriform recess, the thickened and medially positioned aryepiglottic fold, the widened laryngeal pouch, the anteriorly positioned arytenoid cartilage, the thickened vocal fold, and the filled infraglottic space in frontal CT reconstruction. CT images were compared to laryngovideostroboscopy. The most common symptoms of vocal cord paralysis in CT were the deepened epiglottic vallecula and piriform recess, the widened laryngeal pouch with the filled infraglottic space, and the thickened aryepiglottic fold. Regarding the efficiency of the paralysis determination, the three functional techniques of CT larynx imaging used did not differ significantly, and laryngovideostroboscopy demonstrated its advantage over CT. CT of the larynx is a supplementary examination in the diagnosis of vocal fold paralysis, which may enable topographic analysis of the fold dysfunction. The knowledge of morphological CT features of the paralysis may help to prevent false-positive diagnosis of laryngeal cancer. (author)

  20. Protein folding and the organization of the protein topology universe

    DEFF Research Database (Denmark)

    Lindorff-Larsen,, Kresten; Røgen, Peter; Paci, Emanuele

    2005-01-01

    of protein folds that is based on the topological features of the polypeptide backbone, rather than the conventional view that depends on the arrangement of different types of secondary-structure elements. By linking the folding process to the organization of the protein structure universe, we propose......The mechanism by which proteins fold to their native states has been the focus of intense research in recent years. The rate-limiting event in the folding reaction is the formation of a conformation in a set known as the transition-state ensemble. The structural features present within...

  1. Fracture Toughness of Vocal Fold Tissue: A Preliminary Study.

    Science.gov (United States)

    Miri, Amir K; Chen, Lei Xi; Mongrain, Rosaire; Mongeau, Luc

    2016-05-01

    A customized mechanical tester that slices thin, soft samples was used to measure the fracture toughness of vocal fold tissue. Porcine vocal fold lamina propria was subjected to quasi-static, guillotine-like tests at three equally distanced regions along the anterior-posterior direction. The central one-third where high-velocity collisions between vocal folds occur was found to have the maximum fracture toughness. In contrast, the anterior one-third featured a lower toughness. Fracture toughness can be indicative of the risk of benign and malignant lesions in vocal fold tissue. Copyright © 2016 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

  2. Prediction of the optimal set of contacts to fold the smallest knotted protein

    Science.gov (United States)

    Dabrowski-Tumanski, P.; Jarmolinska, A. I.; Sulkowska, J. I.

    2015-09-01

    Knotted protein chains represent a new motif in protein folds. They have been linked to various diseases, and recent extensive analysis of the Protein Data Bank shows that they constitute 1.5% of all deposited protein structures. Despite thorough theoretical and experimental investigations, the role of knots in proteins still remains elusive. Nonetheless, it is believed that knots play an important role in mechanical and thermal stability of proteins. Here, we perform a comprehensive analysis of native, shadow-specific and non-native interactions which describe free energy landscape of the smallest knotted protein (PDB id 2efv). We show that the addition of shadow-specific contacts in the loop region greatly enhances folding kinetics, while the addition of shadow-specific contacts along the C-terminal region (H3 or H4) results in a new folding route with slower kinetics. By means of direct coupling analysis (DCA) we predict non-native contacts which also can accelerate kinetics. Next, we show that the length of the C-terminal knot tail is responsible for the shape of the free energy barrier, while the influence of the elongation of the N-terminus is not significant. Finally, we develop a concept of a minimal contact map sufficient for 2efv protein to fold and analyze properties of this protein using this map.

  3. Prediction of the optimal set of contacts to fold the smallest knotted protein

    International Nuclear Information System (INIS)

    Dabrowski-Tumanski, P; Jarmolinska, A I; Sulkowska, J I

    2015-01-01

    Knotted protein chains represent a new motif in protein folds. They have been linked to various diseases, and recent extensive analysis of the Protein Data Bank shows that they constitute 1.5% of all deposited protein structures. Despite thorough theoretical and experimental investigations, the role of knots in proteins still remains elusive. Nonetheless, it is believed that knots play an important role in mechanical and thermal stability of proteins. Here, we perform a comprehensive analysis of native, shadow-specific and non-native interactions which describe free energy landscape of the smallest knotted protein (PDB id 2efv). We show that the addition of shadow-specific contacts in the loop region greatly enhances folding kinetics, while the addition of shadow-specific contacts along the C-terminal region (H3 or H4) results in a new folding route with slower kinetics. By means of direct coupling analysis (DCA) we predict non-native contacts which also can accelerate kinetics. Next, we show that the length of the C-terminal knot tail is responsible for the shape of the free energy barrier, while the influence of the elongation of the N-terminus is not significant. Finally, we develop a concept of a minimal contact map sufficient for 2efv protein to fold and analyze properties of this protein using this map. (paper)

  4. Architecture and Folding Mechanism of the Azoarcus Group I Pre-tRNA

    Energy Technology Data Exchange (ETDEWEB)

    Rangan,P.; Masquida, B.; Westhof, E.; Woodson, S.

    2004-01-01

    Self-splicing RNAs must evolve to function in their specific exon context. The conformation of a group I pre-tRNA{sup ile} from the bacterium Azoarcus was probed by ribonuclease T1 and hydroxyl radical cleavage, and by native gel electrophoresis. Biochemical data and three-dimensional models of the pre-tRNA showed that the tRNA is folded, and that the tRNA and intron sequences form separate tertiary domains. Models of the active site before steps 1 and 2 of the splicing reaction predict that exchange of the external G-cofactor and the 3{prime}-terminal G is accomplished by a slight conformational change in P9.0 of the Azoarcus group I intron. Kinetic assays showed that the pre-tRNA folds in minutes, much more slowly than the intron alone. The dependence of the folding kinetics on Mg{sup 2+} and the concentration of urea, and RNase T1 experiments showed that formation of native pre-tRNA is delayed by misfolding of P3-P9, including mispairing between residues in P9 and the tRNA. Thus, although the intron and tRNA sequences form separate domains in the native pre-tRNA, their folding is coupled via metastable non-native base-pairs. This could help prevent premature processing of the 5{prime} and 3{prime} ends of unspliced pre-tRNA.

  5. Photonic crystal coupled cavities with increased beaming and free space coupling efficiency

    International Nuclear Information System (INIS)

    Haddadi, S.; Yacomotti, A. M.; Sagnes, I.; Beaudoin, G.; Le Gratiet, L.; Levenson, J. A.; Raineri, F.

    2013-01-01

    We implement the band-folding approach in coupled photonic crystal L3 (three missing holes) nanocavities and demonstrate a dramatic beaming improvement compatible with high-Q operation. Directional laser effect is achieved. In addition, resonant free-space coupling to the symmetric and anti-symmetric hybrid modes of the photonic molecule is shown. We measure the coupling to each mode as a function of the spatial position of the laser spot, which can be used as a technique to probe the symmetry of coupled cavity modes.

  6. Purification of uranium metal

    International Nuclear Information System (INIS)

    Suzuki, Kenji; Shikama, Tatsuo; Ochiai, Akira.

    1993-01-01

    We developed the system for purifying uranium metal and its metallic compounds and for growing highly pure uranium compounds to study their intrinsic physical properties. Uranium metal was zone refined under low contamination conditions as far as possible. The degree of the purity of uranium metal was examined by the conventional electrical resistivity measurement and by the chemical analysis using the inductive coupled plasma emission spectrometry (ICP). The results show that some metallic impurities evaporated by the r.f. heating and other usual metallic impurities moved to the end of a rod with a molten zone. Therefore, we conclude that the zone refining technique is much effective to the removal of metallic impurities and we obtained high purified uranium metal of 99.99% up with regarding to metallic impurities. The maximum residual resistivity ratio, the r.r.r., so far obtained was about 17-20. Using the purified uranium, we are attempting to grow a highly pure uranium-titanium single crystals. (author)

  7. Quantification of fold growth of frontal antiforms in the Zagros fold and thrust belt (Kurdistan, NE Iraq)

    Science.gov (United States)

    Bretis, Bernhard; Bartl, Nikolaus; Graseman, Bernhard; Lockhart, Duncan

    2010-05-01

    The Zagros fold and thrust belt is a seismically active orogen, where actual kinematic models based on GPS networks suggest a north-south shortening between Arabian and Eurasian in the order of 1.5-2.5 cm/yr. Most of this deformation is partitioned in south-southwest oriented folding and thrusting with northwest-southeast to north-south trending dextral strike slip faults. The Zagros fold and thrust belt is of great economic interest because it has been estimated that this area contains about 15% of the global recoverable hydrocarbons. Whereas the SE parts of the Zagros have been investigated by detailed geological studies, the NW extent being part of the Republic of Iraq have experienced considerably less attention. In this study we combine field work and remote sensing techniques in order to investigate the interaction of erosion and fold growth in the area NE of Erbil (Kurdistan, Iraq). In particular we focus on the interaction of the transient development of drainage patterns along growing antiforms, which directly reflects the kinematics of progressive fold growth. Detailed geomorphological studies of the Bana Bawi-, Permam- and Safeen fold trains show that these anticlines have not developed from subcylindrical embryonic folds but they have merged from different fold segments that joined laterally during fold amplification. This fold segments with length between 5 and 25 km have been detected by mapping ancient and modern river courses that initially cut the nose of growing folds and eventually got defeated leaving behind a wind gap. Fold segments, propagating in different directions force rivers to join resulting in steep gorges, which dissect the merging fold noses. Along rapidly lateral growing folds (e.g. at the SE end of the Bana Bawi Anticline) we observed "curved wind gaps", a new type of abandoned river course, where form of the wind gap mimics a formed nose of a growing antiform. The inherited curved segments of uplifted curved river courses strongly

  8. Metal-metal-hofteproteser

    DEFF Research Database (Denmark)

    Ulrich, Michael; Overgaard, Søren; Penny, Jeannette

    2014-01-01

    In Denmark 4,456 metal-on-metal (MoM) hip prostheses have been implanted. Evidence demonstrates that some patients develope adverse biological reactions causing failures of MoM hip arthroplasty. Some reactions might be systemic. Failure rates are associated with the type and the design of the Mo......M hip implant. A Danish surveillance programme has been initiated addressing these problems....

  9. Understanding the folding process of synthetic polymers by small ...

    Indian Academy of Sciences (India)

    WINTEC

    Understanding the folding process of synthetic polymers by small-molecule folding agents. S G RAMKUMAR and S RAMAKRISHNAN*. Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012 e-mail: raman@ipc.iisc.ernet.in. Abstract. Two acceptor containing polyimides PDI and NDI ...

  10. Spatially confined folding of chromatin in the interphase nucleus

    NARCIS (Netherlands)

    Mateos-Langerak, J.; Bohn, M.; de Leeuw, W.; Giromus, O.; Manders, E.M.M.; Verschure, P.J.; Indemans, M.H.G.; Gierman, H.J.; Heermann, D.W.; van Driel, R.; Goetze, S.

    2009-01-01

    Genome function in higher eukaryotes involves major changes in the spatial organization of the chromatin fiber. Nevertheless, our understanding of chromatin folding is remarkably limited. Polymer models have been used to describe chromatin folding. However, none of the proposed models gives a

  11. Landforms along transverse faults parallel to axial zone of folded ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 126; Issue 1. Landforms along transverse faults parallel to axial zone of folded mountain front, north-eastern Kumaun Sub-Himalaya, India. Khayingshing ... Keywords. Himalayan Frontal Thrust; outer Kumaun Himalaya; transverse structure; folded mountain front.

  12. Co-transcriptional folding is encoded within RNA genes

    Directory of Open Access Journals (Sweden)

    Miklós István

    2004-08-01

    Full Text Available Abstract Background Most of the existing RNA structure prediction programs fold a completely synthesized RNA molecule. However, within the cell, RNA molecules emerge sequentially during the directed process of transcription. Dedicated experiments with individual RNA molecules have shown that RNA folds while it is being transcribed and that its correct folding can also depend on the proper speed of transcription. Methods The main aim of this work is to study if and how co-transcriptional folding is encoded within the primary and secondary structure of RNA genes. In order to achieve this, we study the known primary and secondary structures of a comprehensive data set of 361 RNA genes as well as a set of 48 RNA sequences that are known to differ from the originally transcribed sequence units. We detect co-transcriptional folding by defining two measures of directedness which quantify the extend of asymmetry between alternative helices that lie 5' and those that lie 3' of the known helices with which they compete. Results We show with statistical significance that co-transcriptional folding strongly influences RNA sequences in two ways: (1 alternative helices that would compete with the formation of the functional structure during co-transcriptional folding are suppressed and (2 the formation of transient structures which may serve as guidelines for the co-transcriptional folding pathway is encouraged. Conclusions These findings have a number of implications for RNA secondary structure prediction methods and the detection of RNA genes.

  13. Analysis of protein folds using protein contact networks

    Indian Academy of Sciences (India)

    Proteins are important biomolecules, which perform diverse structural and functional roles in living systems. Starting from a linear chain of amino acids, proteins fold to different secondary structures, which then fold through short- and long-range interactions to give rise to the final three-dimensional shapes useful to carry out ...

  14. Competition between folding and glycosylation in the endoplasmic reticulum

    DEFF Research Database (Denmark)

    Holst, B; Bruun, A W; Kielland-Brandt, Morten

    1996-01-01

    Using carboxypeptidase Y in Saccharomyces cerevisiae as a model system, the in vivo relationship between protein folding and N-glycosylation was studied. Seven new sites for N-glycosylation were introduced at positions buried in the folded protein structure. The level of glycosylation of such new...

  15. Analyses of fold profiles by changing weight parameters of NURB ...

    Indian Academy of Sciences (India)

    Manash Pratim Gogoi

    2017-10-06

    Oct 6, 2017 ... try was not simulated earlier from linear viscous rheology, as per Cruikshank and Johnson (1993). Doming of fluid/ductile deforming rocks with a. Newtonian viscous rheology produces parabolic fold morphology (Johnson and Fletcher 1994). On the other hand, the parabolic fold profiles simu- lated in figure ...

  16. Status report on the folded tandem ion accelerator at BARC

    Indian Academy of Sciences (India)

    Folded tandem ion accelerator; charged particle beams; voltage stability; Rutherford backscattering; ion optics; beam lines. Abstract. The folded tandem ion accelerator (FOTIA) facility set up at BARC has become operational. At present, it is used for elemental analysis studies using the Rutherford backscattering technique.

  17. The dominant folding route minimizes backbone distortion in SH3.

    Directory of Open Access Journals (Sweden)

    Heiko Lammert

    Full Text Available Energetic frustration in protein folding is minimized by evolution to create a smooth and robust energy landscape. As a result the geometry of the native structure provides key constraints that shape protein folding mechanisms. Chain connectivity in particular has been identified as an essential component for realistic behavior of protein folding models. We study the quantitative balance of energetic and geometrical influences on the folding of SH3 in a structure-based model with minimal energetic frustration. A decomposition of the two-dimensional free energy landscape for the folding reaction into relevant energy and entropy contributions reveals that the entropy of the chain is not responsible for the folding mechanism. Instead the preferred folding route through the transition state arises from a cooperative energetic effect. Off-pathway structures are penalized by excess distortion in local backbone configurations and contact pair distances. This energy cost is a new ingredient in the malleable balance of interactions that controls the choice of routes during protein folding.

  18. Surfing the free energy landscape of flavodoxin folding

    NARCIS (Netherlands)

    Bollen, Y.J.M.

    2004-01-01

    The research described in this thesis has been carried out to obtain a better understanding of the fundamental rules describing protein folding. Protein folding is the process in which a linear chain of amino acids contracts to a compact state in which it is active. Flavodoxin from Azotobacter

  19. Vocal Fold Mucus Aggregation in Persons with Voice Disorders

    Science.gov (United States)

    Bonilha, Heather Shaw; White, Lisa; Kuckhahn, Kelsey; Gerlach, Terri Treman; Deliyski, Dimitar D.

    2012-01-01

    Mucus aggregation on the vocal folds is a common finding from laryngeal endoscopy. Patients with voice disorders report the presence of mucus aggregation. Patients also report that mucus aggregation causes them to clear their throat, a behavior believed to be harmful to vocal fold mucosa. Even though clinicians and patients report and discuss…

  20. Double folding model analysis of elastic scattering of halo nucleus ...

    Indian Academy of Sciences (India)

    barrier energy have been performed using a potential obtained from the double folding model and are compared with the ... In double folding (DF) model, the real nucleus–nucleus optical potential is given by the expression [9]. V DF(r) = ∫ dr1. ∫ ... expressed as a sum of three Yukawa terms. It is obtained from the fitting of ...

  1. BENIGN LESIONS OF THE VOCAL FOLDS - HISTOPATHOLOGY AND PHONOTRAUMA

    NARCIS (Netherlands)

    DIKKERS, FG; NIKKELS, PGJ

    Benign lesions of the vocal folds have various appearances. Histopathologic examination might provide the true diagnosis. Therefore, histologic slides of 74 patients (92 vocal folds) with clinically well-defined diagnoses were single-blind examined by a pathologist. Single histologic features did

  2. Analyses of fold profiles by changing weight parameters of NURB ...

    Indian Academy of Sciences (India)

    56

    Department of Geology, Sibsagar College, Joysagar, Sivasagar-785665, Assam, INDIA. 2. Department of Earth Sciences, Indian ..... 3rd degree (n=3) cubic NURB folds generated by increasing value of w1=w2=w from 0.1 to 9.9 and increasing R = hL-1. In all cases, h remains constant. 7*4 possibilities of fold geometries ...

  3. Fluorescence of Alexa Fluor dye tracks protein folding

    NARCIS (Netherlands)

    Lindhoud, S.; Westphal, A.H.; Borst, J.W.; Visser, A.J.W.G.; Mierlo, van C.P.M.

    2012-01-01

    Fluorescence spectroscopy is an important tool for the characterization of protein folding. Often, a protein is labeled with appropriate fluorescent donor and acceptor probes and folding-induced changes in Förster Resonance Energy Transfer (FRET) are monitored. However, conformational changes of the

  4. Distributions and pollution assessment of heavy metals Pb, Cd and Cr in the water system of Kendari Bay, Indonesia

    Science.gov (United States)

    Armid, A.; Shinjo, R.; Ruslan, R.; Fahmiati

    2017-02-01

    The concentrations of heavy metals Pb, Cd and Cr in the coastal waters of Kendari Bay were analyzed to assess their pollution status. Water samples from 32 sampling points were analyzed for dissolved heavy metals concentrations by using inductively coupled plasma mass spectrometry (ICP-MS). The RSD(%) of each metal was accounted to analyze the diversity of the heavy metals among 32 sampling points. The results demonstrate that the dissolved heavy metal Pb had the highest concentrations (0.009 to 0.549 μg/L, average = 0.210 μg/L) followed by Cr (0.085 to 0.386 μg/L, average = 0.149 μg/L), and Cd (0.001 to 0.015 μg/L, average = 0.008 μg/L). Based on the the RSD values (Pb = 87.8%, Cd = 45.2% and Cr = 41.3%), it is suggested that the antropogenic activities controls the high diversity of concentrations for heavy metal Pb relative to those of Cd and Cr. Comparing the data with the mean oceanic concentrations, only the concentrations of Pb exceed the mean oceanic level (210 folds). Therefore, the water system of Kendari Bay is severely polluted with heavy metal Pb. More management and treatment should be introduced to protect the marine environment in the study area, especially from Pb pollution.

  5. Method of generating ploynucleotides encoding enhanced folding variants

    Energy Technology Data Exchange (ETDEWEB)

    Bradbury, Andrew M.; Kiss, Csaba; Waldo, Geoffrey S.

    2017-05-02

    The invention provides directed evolution methods for improving the folding, solubility and stability (including thermostability) characteristics of polypeptides. In one aspect, the invention provides a method for generating folding and stability-enhanced variants of proteins, including but not limited to fluorescent proteins, chromophoric proteins and enzymes. In another aspect, the invention provides methods for generating thermostable variants of a target protein or polypeptide via an internal destabilization baiting strategy. Internally destabilization a protein of interest is achieved by inserting a heterologous, folding-destabilizing sequence (folding interference domain) within DNA encoding the protein of interest, evolving the protein sequences adjacent to the heterologous insertion to overcome the destabilization (using any number of mutagenesis methods), thereby creating a library of variants. The variants in the library are expressed, and those with enhanced folding characteristics selected.

  6. Co- and post-translational protein folding in the ER

    DEFF Research Database (Denmark)

    Ellgaard, Lars; McCaul, Nicholas; Chatsisvili, Anna

    2016-01-01

    The biophysical rules that govern folding of small, single-domain proteins in dilute solutions are now quite well understood. The mechanisms underlying co-translational folding of multidomain and membrane-spanning proteins in complex cellular environments are often less clear. The endoplasmic...... and the variety of ER-specific protein modifications. Here, we review chaperone-assisted co- and post-translational folding and assembly in the ER and underline the influence of protein modifications on these processes. We emphasize how method development has helped advance the field by allowing researchers...... to monitor the progression of folding as it occurs inside living cells, while at the same time probing the intricate relationship between protein modifications during folding....

  7. Folding propensity of intrinsically disordered proteins by osmotic stress

    International Nuclear Information System (INIS)

    Mansouri, Amanda L.; Grese, Laura N.; Rowe, Erica L.

    2016-01-01

    Proteins imparted with intrinsic disorder conduct a range of essential cellular functions. To better understand the folding and hydration properties of intrinsically disordered proteins (IDPs), we used osmotic stress to induce conformational changes in nuclear co-activator binding domain (NCBD) and activator for thyroid hormone and retinoid receptor (ACTR). Osmotic stress was applied by the addition of small and polymeric osmolytes, where we discovered that water contributions to NCBD folding always exceeded those for ACTR. Both NCBD and ACTR were found to gain a-helical structure with increasing osmotic stress, consistent with their folding upon NCBD/ACTR complex formation. Using small-angle neutron scattering (SANS), we further characterized NCBD structural changes with the osmolyte ethylene glycol. Here a large reduction in overall size initially occurred before substantial secondary structural change. In conclusion, by focusing on folding propensity, and linked hydration changes, we uncover new insights that may be important for how IDP folding contributes to binding.

  8. Specificity in liquid metal induced embrittlement

    CSIR Research Space (South Africa)

    Fernandes, PJL

    1996-12-01

    Full Text Available One of the most intriguing features of liquid metal induced embrittlement (LMIE) is the observation that some liquid metal-solid metal couples are susceptible to embrittlement, while others appear to be immune. This is referred to as the specificity...

  9. Comparison of different transition metal ions for immobilized metal affinity chromatography of selenoprotein P from human plasma

    DEFF Research Database (Denmark)

    Sidenius, U; Farver, O; Jøns, O

    1999-01-01

    Cu2+, Ni2+, Zn2+, Co2+ and Cd2+ were evaluated in metal ion affinity chromatography for enrichment of selenoprotein P, and immobilized Co2+ affinity chromatography was found to be the most selective chromatographic method. The chromatography was performed by fast protein liquid chromatography...... and the fractionation was followed by analysis of the collected fractions for selenium by inductively coupled plasma mass spectrometry. By the combination of immobilized Co2+ affinity chromatography and heparin affinity chromatography a simple method was developed yielding a 14,800-fold enrichment of selenoprotein P....... The purity of the protein was determined by SDS-PAGE and by sequencing from polyvinylidene difluoride blots of SDS-PAGE gels....

  10. Entropic formulation for the protein folding process: Hydrophobic stability correlates with folding rates

    Science.gov (United States)

    Dal Molin, J. P.; Caliri, A.

    2018-01-01

    Here we focus on the conformational search for the native structure when it is ruled by the hydrophobic effect and steric specificities coming from amino acids. Our main tool of investigation is a 3D lattice model provided by a ten-letter alphabet, the stereochemical model. This minimalist model was conceived for Monte Carlo (MC) simulations when one keeps in mind the kinetic behavior of protein-like chains in solution. We have three central goals here. The first one is to characterize the folding time (τ) by two distinct sampling methods, so we present two sets of 103 MC simulations for a fast protein-like sequence. The resulting sets of characteristic folding times, τ and τq were obtained by the application of the standard Metropolis algorithm (MA), as well as by an enhanced algorithm (Mq A). The finding for τq shows two things: (i) the chain-solvent hydrophobic interactions {hk } plus a set of inter-residues steric constraints {ci,j } are able to emulate the conformational search for the native structure. For each one of the 103MC performed simulations, the target is always found within a finite time window; (ii) the ratio τq / τ ≅ 1 / 10 suggests that the effect of local thermal fluctuations, encompassed by the Tsallis weight, provides to the chain an innate efficiency to escape from energetic and steric traps. We performed additional MC simulations with variations of our design rule to attest this first result, both algorithms the MA and the Mq A were applied to a restricted set of targets, a physical insight is provided. Our second finding was obtained by a set of 600 independent MC simulations, only performed with the Mq A applied to an extended set of 200 representative targets, our native structures. The results show how structural patterns should modulate τq, which cover four orders of magnitude; this finding is our second goal. The third, and last result, was obtained with a special kind of simulation performed with the purpose to explore a

  11. Dark coupling

    International Nuclear Information System (INIS)

    Gavela, M.B.; Hernández, D.; Honorez, L. Lopez; Mena, O.; Rigolin, S.

    2009-01-01

    The two dark sectors of the universe—dark matter and dark energy—may interact with each other. Background and linear density perturbation evolution equations are developed for a generic coupling. We then establish the general conditions necessary to obtain models free from non-adiabatic instabilities. As an application, we consider a viable universe in which the interaction strength is proportional to the dark energy density. The scenario does not exhibit ''phantom crossing'' and is free from instabilities, including early ones. A sizeable interaction strength is compatible with combined WMAP, HST, SN, LSS and H(z) data. Neutrino mass and/or cosmic curvature are allowed to be larger than in non-interacting models. Our analysis sheds light as well on unstable scenarios previously proposed

  12. Effect of sugarcane biopolymer gel injected in rabbit vocal fold

    Directory of Open Access Journals (Sweden)

    Rodrigo Augusto de Souza Leão

    2014-06-01

    Full Text Available INTRODUCTION: Alterations in the vocal folds that involve volume reduction and glottal closure failure result in exaggerated air escape during speech. For such situations, the use of implants or grafts of different materials has been proposed. OBJECTIVE: To define the effect of sugarcane biopolymer gel when implanted in the vocal folds of rabbits. METHODS: This was an experimental study. The vocal folds of rabbits injected with sugarcane biopolymer and saline solution were histologically evaluated after 21 and 90 days. RESULTS: Mild to moderate inflammation and increased volume were observed in all vocal folds injected with biopolymer, when compared to controls. There were no cases of necrosis or calcification. DISCUSSION: This study showed higher inflammatory reaction in cases than in controls and biopolymer biointegration to the vocal fold. This fibrogenic response with absence of epithelial repercussions suggests that the biopolymer in its gel form can be bioactive and preserve the normal vibratory function of the epithelium. CONCLUSION: We show that in spite of producing an inflammatory reaction in vocal fold tissues, the material remained in vocal fold throughout the study period.

  13. Analyzing the effect of homogeneous frustration in protein folding.

    Science.gov (United States)

    Contessoto, Vinícius G; Lima, Debora T; Oliveira, Ronaldo J; Bruni, Aline T; Chahine, Jorge; Leite, Vitor B P

    2013-10-01

    The energy landscape theory has been an invaluable theoretical framework in the understanding of biological processes such as protein folding, oligomerization, and functional transitions. According to the theory, the energy landscape of protein folding is funneled toward the native state, a conformational state that is consistent with the principle of minimal frustration. It has been accepted that real proteins are selected through natural evolution, satisfying the minimum frustration criterion. However, there is evidence that a low degree of frustration accelerates folding. We examined the interplay between topological and energetic protein frustration. We employed a Cα structure-based model for simulations with a controlled nonspecific energetic frustration added to the potential energy function. Thermodynamics and kinetics of a group of 19 proteins are completely characterized as a function of increasing level of energetic frustration. We observed two well-separated groups of proteins: one group where a little frustration enhances folding rates to an optimal value and another where any energetic frustration slows down folding. Protein energetic frustration regimes and their mechanisms are explained by the role of non-native contact interactions in different folding scenarios. These findings strongly correlate with the protein free-energy folding barrier and the absolute contact order parameters. These computational results are corroborated by principal component analysis and partial least square techniques. One simple theoretical model is proposed as a useful tool for experimentalists to predict the limits of improvements in real proteins. Copyright © 2013 Wiley Periodicals, Inc.

  14. The role of the mesenchyme in cranial neural fold elevation

    Energy Technology Data Exchange (ETDEWEB)

    Morris-Wiman, J.A.

    1988-01-01

    It has been previously postulated that the expansion of an hyaluronate-rich extracellular matrix in the fold mesenchyme is responsible for neural fold elevation. In this study we provide evidence that such expansions may play an important role in cranial neural fold elevation by pushing the folds towards the dorsal midline to assist in their elevation. For mesenchymal expansion to result in fold elevation, hyaluronate (HA) and mesenchymal cells must be non-randomly distributed within the mesenchyme. Patterns of mesenchymal cell distribution and cell proliferation were analyzed using the computer-assisted method of smoothed spatial averaging. The distribution of Alcian blue-stained and {sup 3}H-glucosamine-labelled HA was also analyzed during cranial neural fold elevation using established image processing techniques. Analysis of the distribution of {sup 3}H-thymidine-labelled mesenchymal cells indicated that differential mitotic activity was not responsible for decreased mesenchymal cell density. Likewise, analysis of distribution patterns of {sup 3}H-glucosamine-labelled HA indicated that decreased HA concentration was not produced by regional differences in HA synthesis. These results suggest that decreases in mesenchymal cell density and HA concentration that occur during neural fold elevation are produced by mesenchymal expansion.

  15. The role of the mesenchyme in cranial neural fold elevation

    International Nuclear Information System (INIS)

    Morris-Wiman, J.A.

    1988-01-01

    It has been previously postulated that the expansion of an hyaluronate-rich extracellular matrix in the fold mesenchyme is responsible for neural fold elevation. In this study we provide evidence that such expansions may play an important role in cranial neural fold elevation by pushing the folds towards the dorsal midline to assist in their elevation. For mesenchymal expansion to result in fold elevation, hyaluronate (HA) and mesenchymal cells must be non-randomly distributed within the mesenchyme. Patterns of mesenchymal cell distribution and cell proliferation were analyzed using the computer-assisted method of smoothed spatial averaging. The distribution of Alcian blue-stained and 3 H-glucosamine-labelled HA was also analyzed during cranial neural fold elevation using established image processing techniques. Analysis of the distribution of 3 H-thymidine-labelled mesenchymal cells indicated that differential mitotic activity was not responsible for decreased mesenchymal cell density. Likewise, analysis of distribution patterns of 3 H-glucosamine-labelled HA indicated that decreased HA concentration was not produced by regional differences in HA synthesis. These results suggest that decreases in mesenchymal cell density and HA concentration that occur during neural fold elevation are produced by mesenchymal expansion

  16. Origami-Inspired Folding of Thick, Rigid Panels

    Science.gov (United States)

    Trease, Brian P.; Thomson, Mark W.; Sigel, Deborah A.; Walkemeyer, Phillip E.; Zirbel, Shannon; Howell, Larry; Lang, Robert

    2014-01-01

    To achieve power of 250 kW or greater, a large compression ratio of stowed-to-deployed area is needed. Origami folding patterns were used to inspire the folding of a solar array to achieve synchronous deployment; however, origami models are generally created for near-zero-thickness material. Panel thickness is one of the main challenges of origami-inspired design. Three origami-inspired folding techniques (flasher, square twist, and map fold) were created with rigid panels and hinges. Hinge components are added to the model to enable folding of thick, rigid materials. Origami models are created assuming zero (or near zero) thickness. When a material with finite thickness is used, the panels are required to bend around an increasingly thick fold as they move away from the center of the model. The two approaches for dealing with material thickness are to use membrane hinges to connect the panels, or to add panel hinges, or hinges of the same thickness, at an appropriate width to enable folding.

  17. Endoscopic Anatomy of the Tensor Fold and Anterior Attic.

    Science.gov (United States)

    Li, Bin; Doan, Phi; Gruhl, Robert R; Rubini, Alessia; Marchioni, Daniele; Fina, Manuela

    2018-02-01

    Objectives The objectives of the study were to (1) study the anatomical variations of the tensor fold and its anatomic relation with transverse crest, supratubal recess, and anterior epitympanic space and (2) explore the most appropriate endoscopic surgical approach to each type of the tensor fold variants. Study Design Cadaver dissection study. Setting Temporal bone dissection laboratory. Subjects and Methods Twenty-eight human temporal bones (26 preserved and 2 fresh) were dissected through an endoscopic transcanal approach between September 2016 and June 2017. The anatomical variations of the tensor fold, transverse crest, supratubal recess, and anterior epitympanic space were studied before and after removing ossicles. Results Three different tensor fold orientations were observed: vertical (type A, 11/28, 39.3%) with attachment to the transverse crest, oblique (type B, 13/28, 46.4%) with attachment to the anterior tegmen tympani, and horizontal (type C, 4/28, 14.3%) with attachment to the tensor tympani canal. The tensor fold was a complete membrane in 20 of 28 (71.4%) specimens, preventing direct ventilation between the supratubal recess and anterior epitympanic space. We identified 3 surgical endoscopic approaches, which allowed visualization of the tensor fold without removing the ossicles. Conclusions The orientation of the tensor fold is the determining structure that dictates the conformation and limits of the epitympanic space. We propose a classification of the tensor fold based on 3 anatomical variants. We also describe 3 different minimally invasive endoscopic approaches to identify the orientation of the tensor fold while maintaining ossicular chain continuity.

  18. A nomenclature paradigm for benign midmembranous vocal fold lesions.

    Science.gov (United States)

    Rosen, Clark A; Gartner-Schmidt, Jackie; Hathaway, Bridget; Simpson, C Blake; Postma, Gregory N; Courey, Mark; Sataloff, Robert T

    2012-06-01

    There is a significant lack of uniform agreement regarding nomenclature for benign vocal fold lesions (BVFLs). This confusion results in difficulty for clinicians communicating with their patients and with each other. In addition, BVFL research and comparison of treatment methods are hampered by the lack of a detailed and uniform BVFL nomenclature. Clinical consensus conferences were held to develop an initial BVFL nomenclature paradigm. Perceptual video analysis was performed to validate the stroboscopy component of the paradigm. The culmination of the consensus conferences and the video-perceptual analysis was used to evaluate the BVFL nomenclature paradigm using a retrospective review of patients with BVFL. An initial BVFL nomenclature paradigm was proposed utilizing detailed definitions relating to vocal fold lesion morphology, stroboscopy, response to voice therapy and intraoperative findings. Video-perceptual analysis of stroboscopy demonstrated that the proposed binary stroboscopy system used in the BVFL nomenclature paradigm was valid and widely applicable. Retrospective review of 45 patients with BVFL followed to the conclusion of treatment demonstrated that slight modifications of the initial BVFL nomenclature paradigm were required. With the modified BVFL nomenclature paradigm, 96% of the patients fit into the predicted pattern and definitions of the BVFL nomenclature system. This study has validated a multidimensional BVFL nomenclature paradigm. This vocal fold nomenclature paradigm includes nine distinct vocal fold lesions: vocal fold nodules, vocal fold polyp, pseudocyst, vocal fold cyst (subepithelial or ligament), nonspecific vocal fold lesion, vocal fold fibrous mass (subepithelial or ligament), and reactive lesion. Copyright © 2011 The American Laryngological, Rhinological, and Otological Society, Inc.

  19. Molecular dynamics studies of protein folding and aggregation

    Science.gov (United States)

    Ding, Feng

    This thesis applies molecular dynamics simulations and statistical mechanics to study: (i) protein folding; and (ii) protein aggregation. Most small proteins fold into their native states via a first-order-like phase transition with a major free energy barrier between the folded and unfolded states. A set of protein conformations corresponding to the free energy barrier, Delta G >> kBT, are the folding transition state ensemble (TSE). Due to their evasive nature, TSE conformations are hard to capture (probability ∝ exp(-DeltaG/k BT)) and characterize. A coarse-grained discrete molecular dynamics model with realistic steric constraints is constructed to reproduce the experimentally observed two-state folding thermodynamics. A kinetic approach is proposed to identify the folding TSE. A specific set of contacts, common to the TSE conformations, is identified as the folding nuclei which are necessary to be formed in order for the protein to fold. Interestingly, the amino acids at the site of the identified folding nuclei are highly conserved for homologous proteins sharing the same structures. Such conservation suggests that amino acids that are important for folding kinetics are under selective pressure to be preserved during the course of molecular evolution. In addition, studies of the conformations close to the transition states uncover the importance of topology in the construction of order parameter for protein folding transition. Misfolded proteins often form insoluble aggregates, amyloid fibrils, that deposit in the extracellular space and lead to a type of disease known as amyloidosis. Due to its insoluble and non-crystalline nature, the aggregation structure and, thus the aggregation mechanism, has yet to be uncovered. Discrete molecular dynamics studies reveal an aggregate structure with the same structural signatures as in experimental observations and show a nucleation aggregation scenario. The simulations also suggest a generic aggregation mechanism

  20. Compression induced folding of a sheet: An integrable system

    Science.gov (United States)

    Diamant, Haim; Witten, Thomas A.

    2012-02-01

    The apparently intractable shape of a fold in a compressed elastic film lying on a fluid substrate is found to have an exact solution. Such systems buckle at a nonzero wave vector set by the bending stiffness of the film and the weight of the substrate fluid. Our solution describes the entire progression from a weakly displaced sinusoidal buckling to a single large fold that contacts itself. The pressure decrease is exactly quadratic in the lateral displacement. We demonstrate a subtle connection to the sine-Gordon problem, which reveals a new symmetry in the folding phenomenon.