Electronic structure of semiconductor interfaces

Energy Technology Data Exchange (ETDEWEB)

Herman, F

1983-02-01

The study of semiconductor interfaces is one of the most active and exciting areas of current semiconductor research. Because interfaces play a vital role in modern semiconductor technology (integrated circuits, heterojunction lasers, solar cells, infrared detectors, etc.), there is a strong incentive to understand interface properties at a fundamental level and advance existing technology thereby. At the same time, technological advances such as molecular beam epitaxy have paved the way for the fabrication of semiconductor heterojunctions and superlattices of novel design which exhibit unusual electronic, optical, and magnetic properties and offer unique opportunities for fundamental scientific research. A general perspective on this subject is offered treating such topics as the atomic and electronic structure of semiconductor surfaces and interfaces; oxidation and oxide layers; semiconductor heterojunctions and superlattices; rectifying metal-semiconductor contacts; and interface reactions. Recent progress is emphasized and some future directions are indicated. In addition, the role that large-scale scientific computation has played in furthering our theoretical understanding of semiconductor surfaces and interfaces is discussed. Finally, the nature of theoretical models, and the role they play in describing the physical world is considered.

Electronic structure of semiconductor interfaces

International Nuclear Information System (INIS)

Herman, F.

1983-01-01

The study of semiconductor interfaces is one of the most active and exciting areas of current semiconductor research. Because interfaces play a vital role in modern semiconductor technology (integrated circuits, heterojunction lasers, solar cells, infrared detectors, etc.), there is a strong incentive to understand interface properties at a fundamental level and advance existing technology thereby. At the same time, technological advances such as molecular beam epitaxy have paved the way for the fabrication of semiconductor heterojunctions and superlattices of novel design which exhibit unusual electronic, optical, and magnetic properties and offer unique opportunities for fundamental scientific research. A general perspective on this subject is offered treating such topics as the atomic and electronic structure of semiconductor surfaces and interfaces; oxidation and oxide layers; semiconductor heterojunctions and superlattices; rectifying metal-semiconductor contacts; and interface reactions. Recent progress is emphasized and some future directions are indicated. In addition, the role that large-scale scientific computation has played in furthering our theoretical understanding of semiconductor surfaces and interfaces is discussed. Finally, the nature of theoretical models, and the role they play in describing the physical world is considered. (Author) [pt

Transire, a Program for Generating Solid-State Interface Structures

Science.gov (United States)

2017-09-14

ARL-TR-8134 ● SEP 2017 US Army Research Laboratory Transire, a Program for Generating Solid-State Interface Structures by...Program for Generating Solid-State Interface Structures by Caleb M Carlin and Berend C Rinderspacher Weapons and Materials Research Directorate, ARL...

PREFACE: Liquid-solid interfaces: structure and dynamics from spectroscopy and simulations Liquid-solid interfaces: structure and dynamics from spectroscopy and simulations

Science.gov (United States)

Gaigeot, Marie-Pierre; Sulpizi, Marialore

2012-03-01

/computational communities. On the experimental side, surface specific techniques, such as non-linear optical spectroscopy (sum frequency generation spectroscopy (SFG) and second harmonic generation (SHG)), surface sensitive x-ray scattering, in situ scanning tunneling microscopy (STM) and infrared reflection absorption spectroscopy provide information on layers of nanometric thickness at the interface. On the other hand, it is quite clear that the experiments require theoretical modelling in order to dissect the experimental results and to rationalize the different factors that contribute to the interfacial properties. In this respect molecular dynamics simulations are a major tool. While many successes have already been achieved with molecular dynamics simulations based on empirical force fields, first principles molecular dynamics simulations are now emerging as the other major approach where structure and reactivity are treated in a consistent way. Recent progress within the past 3-5 years on efficient treatments of basis sets and long range interactions in density functional theory (DFT) indeed extend such simulation capabilities to hundreds and thousands of atoms, thus allowing realistic models for interfaces to be tackled, maintaining first principles quality. Most of these simulations bring information on the structural organization of the solvent in the interfacial region between the solid and the liquid, but very few investigate the supplementary challenge of extracting vibrational spectroscopic fingerprints of the interface and, in particular, the direct modeling of the vibrational sum frequency generation (VSFG) non-linear spectra. The present special section reports an interesting contribution from the group of R Y Shen who pioneered VSFG optical experiments. They show how VSFG measurements can be used to unravel the behavior of interfacial water on alumina Al2O3 as a function of pH. The groups of A Hodgson and C Busse respectively provide complementary experiments based on low

Direct experimental determination of the atomic structure at internal interfaces

Energy Technology Data Exchange (ETDEWEB)

Browning, N.D. [Oak Ridge National Lab., TN (United States)]|[Illinois Univ., Chicago, IL (United States); Pennycook, S.J. [Oak Ridge National Lab., TN (United States)

1995-07-01

A crucial first step in understanding the effect that internal interfaces have on the properties of materials is the ability to determine the atomic structure at the interface. As interfaces can contain atomic disorder, dislocations, segregated impurities and interphases, sensitivity to all of these features is essential for complete experimental characterization. By combining Z-contrast imaging and electron energy loss spectroscopy (EELS) in a dedicated scanning transmission electron microscope (STEM), the ability to probe the structure, bonding and composition at interfaces with the necessary atomic resolution has been obtained. Experimental conditions can be controlled to provide, simultaneously, both incoherent imaging and spectroscopy. This enables interface structures observed in the image to be interpreted intuitively and the bonding in a specified atomic column to be probed directly by EELS. The bonding and structure information can then be correlated using bond-valence sum analysis to produce structural models. This technique is demonstrated for 25{degrees}, 36{degrees} and 67{degrees} symmetric and 45{degrees} and 25{degrees} asymmetric [001] tilt grain boundaries in SrTiO{sub 3} The structures of both types of boundary were found to contain partially occupied columns in the boundary plane. From these experimental results, a series of structural units were identified which could be combined, using continuity of gain boundary structure principles, to construct all [001] tilt boundaries in SrTiO{sub 3}. Using these models, the ability of this technique to address the issues of vacancies and dopant segregation at grain boundaries in electroceramics is discussed.

ELSI: A unified software interface for Kohn-Sham electronic structure solvers

Science.gov (United States)

Yu, Victor Wen-zhe; Corsetti, Fabiano; García, Alberto; Huhn, William P.; Jacquelin, Mathias; Jia, Weile; Lange, Björn; Lin, Lin; Lu, Jianfeng; Mi, Wenhui; Seifitokaldani, Ali; Vázquez-Mayagoitia, Álvaro; Yang, Chao; Yang, Haizhao; Blum, Volker

2018-01-01

Solving the electronic structure from a generalized or standard eigenproblem is often the bottleneck in large scale calculations based on Kohn-Sham density-functional theory. This problem must be addressed by essentially all current electronic structure codes, based on similar matrix expressions, and by high-performance computation. We here present a unified software interface, ELSI, to access different strategies that address the Kohn-Sham eigenvalue problem. Currently supported algorithms include the dense generalized eigensolver library ELPA, the orbital minimization method implemented in libOMM, and the pole expansion and selected inversion (PEXSI) approach with lower computational complexity for semilocal density functionals. The ELSI interface aims to simplify the implementation and optimal use of the different strategies, by offering (a) a unified software framework designed for the electronic structure solvers in Kohn-Sham density-functional theory; (b) reasonable default parameters for a chosen solver; (c) automatic conversion between input and internal working matrix formats, and in the future (d) recommendation of the optimal solver depending on the specific problem. Comparative benchmarks are shown for system sizes up to 11,520 atoms (172,800 basis functions) on distributed memory supercomputing architectures.

First-principles study of the structure properties of Al(111)/6H-SiC(0001) interfaces

Science.gov (United States)

Wu, Qingjie; Xie, Jingpei; Wang, Changqing; Li, Liben; Wang, Aiqin; Mao, Aixia

2018-04-01

This paper presents a systematic study on the energetic and electronic structure of the Al(111)/6H-SiC(0001) interfaces by using first-principles calculation with density functional theory (DFT). There are all three situations for no-vacuum layer of Al/SiC superlattics, and two cases of C-terminated and Si-terminated interfaces are compared and analyzed. Through the density of states analysis, the initial information of interface combination is obtained. Then the supercells are stretched vertically along the z-axis, and the fracture of the interface is obtained, and it is pointed out that C-terminated SiC and Al interfaces have a better binding property. And, the fracture positions of C-terminated and Si-terminated interfaces are different in the process of stretching. Then, the distance variation in the process of stretching, the charge density differences, and the distribution of the electrons near the interface are analyzed. Al these work makes the specific reasons for the interface fracture are obtained at last.

The electrochemical transfer reactions and the structure of the iron|oxide layer|electrolyte interface

International Nuclear Information System (INIS)

Petrović, Željka; Metikoš-Huković, Mirjana; Babić, Ranko

2012-01-01

The thickness, barrier (protecting) and semiconducting properties of the potentiostatically formed oxide films on the pure iron electrode in an aqueous borate buffer solution were investigated by electrochemical quartz crystal nanobalance (EQCN), electrochemical impedance spectroscopy (EIS), and Mott–Schottky (MS) analysis. The thicknesses of the prepassive Fe(II)hydroxide layer (up to monolayer) nucleated on the bare iron surface and the passive Fe(II)/Fe(III) layer (up to 2 nm), deposited on the top of the first one, were determined using in situ gravimetry. Electronic properties of iron prepassive and passive films as well as ionic and electronic transfer reactions at the film|solution interface were discussed on the basis of a band structure model of the surface oxide film and the potential distribution at the interface. The anodic oxide film formation and cathodic decomposition are coupled processes and their reversible inter-conversion is mediated by the availability of free charge carriers on the electrode|solution interface. The structure of the reversible double layer at the iron oxide|solution interface was discussed based on the concept of the specific adsorption of the imidazolium cation on the negatively charged electrode surface at pH > pH pzc .

Structure and chemistry of the Si(111)/AlN interface

Science.gov (United States)

Radtke, G.; Couillard, M.; Botton, G. A.; Zhu, D.; Humphreys, C. J.

2012-01-01

We investigate the atomic structure and the chemistry of the Si(111)/AlN interface for an AlN film grown at low-temperature (735 °C) by metalorganic vapor phase epitaxy. A heterogeneous interface is formed from the alternation of crystallographically abrupt and partly amorphous regions. The polarity of the AlN film, along with the projected atomic structure of the crystalline interface, is retrieved using high-angle annular dark field imaging, and a model, based on these experimental observations, is proposed for the bonding at the interface. Electron energy-loss spectrum-imaging, however, also reveals a chemical intermixing, placing our growth conditions at the onset of SiNx interlayer formation.

Interface stability of granular filter structures under currents

NARCIS (Netherlands)

Verheij, H.J.; Hoffmans, G.; Dorst, K.; Van de Sande, S.

2012-01-01

Granular filters are used for protection of structures against scour and erosion. For a proper functioning it is necessary that the interfaces between the filter structure, the subsoil and the water flowing above the filter structure are stable. Stability means that there is no transport of subsoil

Landau levels in biased graphene structures with monolayer-bilayer interfaces

Science.gov (United States)

Mirzakhani, M.; Zarenia, M.; Vasilopoulos, P.; Ketabi, S. A.; Peeters, F. M.

2017-09-01

The electron energy spectrum in monolayer-bilayer-monolayer and in bilayer-monolayer-bilayer graphene structures is investigated and the effects of a perpendicular magnetic field and electric bias are studied. Different types of monolayer-bilayer interfaces are considered as zigzag (ZZ) or armchair (AC) junctions which modify considerably the bulk Landau levels (LLs) when the spectra are plotted as a function of the center coordinate of the cyclotron orbit. Far away from the two interfaces, one obtains the well-known LLs for extended monolayer or bilayer graphene. The LL structure changes significantly at the two interfaces or junctions where the valley degeneracy is lifted for both types of junctions, especially when the distance between them is approximately equal to the magnetic length. Varying the nonuniform bias and the width of this junction-to-junction region in either structure strongly influence the resulting spectra. Significant differences exist between ZZ and AC junctions in both structures. The densities of states (DOSs) for unbiased structures are symmetric in energy whereas those for biased structures are asymmetric. An external bias creates interface LLs in the gaps between the LLs of the unbiased system in which the DOS can be quite small. Such a pattern of LLs can be probed by scanning tunneling microscopy.

Soil-Framed Structure Interaction Analysis - A New Interface Element

Directory of Open Access Journals (Sweden)

M. Dalili Shoaei

Full Text Available AbstractInterfacial behavior between soil and shallow foundation has been found so influential to combined soil-footing performance and redistribution of forces in the superstructure. This study introduces a new thin-layer interface element formulated within the context of finite element method to idealize interfacial behavior of soil-framed structure interaction with new combination of degrees of freedom at top and bottom sides of the interface element, compatible with both isoparametric beam and quadrilateral element. This research also tends to conduct a parametric study on respective parameters of the new joint element. Presence of interface element showed considerable changes in the performance of the framed structure under quasi-static loading.

Structural adaptation of the subunit interface of oligomeric thermophilic and hyperthermophilic enzymes.

Science.gov (United States)

Maugini, Elisa; Tronelli, Daniele; Bossa, Francesco; Pascarella, Stefano

2009-04-01

Enzymes from thermophilic and, particularly, from hyperthermophilic organisms are surprisingly stable. Understanding of the molecular origin of protein thermostability and thermoactivity attracted the interest of many scientist both for the perspective comprehension of the principles of protein structure and for the possible biotechnological applications through application of protein engineering. Comparative studies at sequence and structure levels were aimed at detecting significant differences of structural parameters related to protein stability between thermophilic and hyperhermophilic structures and their mesophilic homologs. Comparative studies were useful in the identification of a few recurrent themes which the evolution utilized in different combinations in different protein families. These studies were mostly carried out at the monomer level. However, maintenance of a proper quaternary structure is an essential prerequisite for a functional macromolecule. At the environmental temperatures experienced typically by hyper- and thermophiles, the subunit interactions mediated by the interface must be sufficiently stable. Our analysis was therefore aimed at the identification of the molecular strategies adopted by evolution to enhance interface thermostability of oligomeric enzymes. The variation of several structural properties related to protein stability were tested at the subunit interfaces of thermophilic and hyperthermophilic oligomers. The differences of the interface structural features observed between the hyperthermophilic and thermophilic enzymes were compared with the differences of the same properties calculated from pairwise comparisons of oligomeric mesophilic proteins contained in a reference dataset. The significance of the observed differences of structural properties was measured by a t-test. Ion pairs and hydrogen bonds do not vary significantly while hydrophobic contact area increases specially in hyperthermophilic interfaces. Interface

JAIL: a structure-based interface library for macromolecules.

Science.gov (United States)

Günther, Stefan; von Eichborn, Joachim; May, Patrick; Preissner, Robert

2009-01-01

The increasing number of solved macromolecules provides a solid number of 3D interfaces, if all types of molecular contacts are being considered. JAIL annotates three different kinds of macromolecular interfaces, those between interacting protein domains, interfaces of different protein chains and interfaces between proteins and nucleic acids. This results in a total number of about 184,000 database entries. All the interfaces can easily be identified by a detailed search form or by a hierarchical tree that describes the protein domain architectures classified by the SCOP database. Visual inspection of the interfaces is possible via an interactive protein viewer. Furthermore, large scale analyses are supported by an implemented sequential and by a structural clustering. Similar interfaces as well as non-redundant interfaces can be easily picked out. Additionally, the sequential conservation of binding sites was also included in the database and is retrievable via Jmol. A comprehensive download section allows the composition of representative data sets with user defined parameters. The huge data set in combination with various search options allow a comprehensive view on all interfaces between macromolecules included in the Protein Data Bank (PDB). The download of the data sets supports numerous further investigations in macromolecular recognition. JAIL is publicly available at http://bioinformatics.charite.de/jail.

Pathways to Structure-Property Relationships of Peptide-Materials Interfaces: Challenges in Predicting Molecular Structures.

Science.gov (United States)

Walsh, Tiffany R

2017-07-18

An in-depth appreciation of how to manipulate the molecular-level recognition between peptides and aqueous materials interfaces, including nanoparticles, will advance technologies based on self-organized metamaterials for photonics and plasmonics, biosensing, catalysis, energy generation and harvesting, and nanomedicine. Exploitation of the materials-selective binding of biomolecules is pivotal to success in these areas and may be particularly key to producing new hierarchically structured biobased materials. These applications could be accomplished by realizing preferential adsorption of a given biomolecule onto one materials composition over another, one surface facet over another, or one crystalline polymorph over another. Deeper knowledge of the aqueous abiotic-biotic interface, to establish clear structure-property relationships in these systems, is needed to meet this goal. In particular, a thorough structural characterization of the surface-adsorbed peptides is essential for establishing these relationships but can often be challenging to accomplish via experimental approaches alone. In addition to myriad existing challenges associated with determining the detailed molecular structure of any molecule adsorbed at an aqueous interface, experimental characterization of materials-binding peptides brings new, complex challenges because many materials-binding peptides are thought to be intrinsically disordered. This means that these peptides are not amenable to experimental techniques that rely on the presence of well-defined secondary structure in the peptide when in the adsorbed state. To address this challenge, and in partnership with experiment, molecular simulations at the atomistic level can bring complementary and critical insights into the origins of this abiotic/biotic recognition and suggest routes for manipulating this phenomenon to realize new types of hybrid materials. For the reasons outlined above, molecular simulation approaches also face

Electronic structure imperfections and chemical bonding at graphene interfaces

Science.gov (United States)

Schultz, Brian Joseph

nanomaterial with lateral dimensions in the hundreds of microns if not larger, with a corresponding atomic vertical thickness poses significant difficulties. Graphene's unique structure is dominated by surface area or potentially hybridized interfaces; consequently, the true realization of this remarkable nanomaterial in device constructs relies on engineering graphene interfaces at the surface in order to controllably mold the electronic structure. Near-edge X-ray absorption fine-structure (NEXAFS) spectroscopy and the transmission mode analogue scanning transmission X-ray microscopy (STXM) are particularly useful tools to study the unoccupied states of graphene and graphene interfaces. In addition, polarized NEXAFS and STXM studies provide information on surface orientation, bond sterics, and the extent of substrate alignment before and after interfacial hybridization. The work presented in this dissertation is fundamentally informed by NEXAFS and STXM measurements on graphene/metal, graphene/dielectric, and graphene/organic interfaces. We start with a general review of the electronic structure of freestanding graphene and graphene interfaces in Chapter 1. In Chapter 2, we investigate freestanding single-layer graphene via STXM and NEXAFS demonstrating that electronic structure heterogeneities from synthesis and processing are ubiquitous in 2-dimensional graphene. We show the mapping of discrete charge transfer regions as a result of doped impurities that decorate the surfaces of graphene and that transfer processing imparts local electronic corrugations or ripples. In corroboration with density functional theory, definitive assignments to the spectral features, global steric orientations of the localized domains, and quantitative charge transfer schemes are evidenced. In the following chapters, we deliberately (Chapter 3) incorporate substitutional nitrogen into reduced graphene oxide to induce C--N charge redistribution and improve global conductivity, (Chapter 4

Analysis of binding properties and specificity through identification of the interface forming residues (IFR for serine proteases in silico docked to different inhibitors

Directory of Open Access Journals (Sweden)

da Silveira Carlos H

2010-10-01

Full Text Available Abstract Background Enzymes belonging to the same super family of proteins in general operate on variety of substrates and are inhibited by wide selection of inhibitors. In this work our main objective was to expand the scope of studies that consider only the catalytic and binding pocket amino acids while analyzing enzyme specificity and instead, include a wider category which we have named the Interface Forming Residues (IFR. We were motivated to identify those amino acids with decreased accessibility to solvent after docking of different types of inhibitors to sub classes of serine proteases and then create a table (matrix of all amino acid positions at the interface as well as their respective occupancies. Our goal is to establish a platform for analysis of the relationship between IFR characteristics and binding properties/specificity for bi-molecular complexes. Results We propose a novel method for describing binding properties and delineating serine proteases specificity by compiling an exhaustive table of interface forming residues (IFR for serine proteases and their inhibitors. Currently, the Protein Data Bank (PDB does not contain all the data that our analysis would require. Therefore, an in silico approach was designed for building corresponding complexes The IFRs are obtained by "rigid body docking" among 70 structurally aligned, sequence wise non-redundant, serine protease structures with 3 inhibitors: bovine pancreatic trypsin inhibitor (BPTI, ecotine and ovomucoid third domain inhibitor. The table (matrix of all amino acid positions at the interface and their respective occupancy is created. We also developed a new computational protocol for predicting IFRs for those complexes which were not deciphered experimentally so far, achieving accuracy of at least 0.97. Conclusions The serine proteases interfaces prefer polar (including glycine residues (with some exceptions. Charged residues were found to be uniquely prevalent at the

Analysis of binding properties and specificity through identification of the interface forming residues (IFR) for serine proteases in silico docked to different inhibitors.

Science.gov (United States)

Ribeiro, Cristina; Togawa, Roberto C; Neshich, Izabella A P; Mazoni, Ivan; Mancini, Adauto L; Minardi, Raquel C de Melo; da Silveira, Carlos H; Jardine, José G; Santoro, Marcelo M; Neshich, Goran

2010-10-20

Enzymes belonging to the same super family of proteins in general operate on variety of substrates and are inhibited by wide selection of inhibitors. In this work our main objective was to expand the scope of studies that consider only the catalytic and binding pocket amino acids while analyzing enzyme specificity and instead, include a wider category which we have named the Interface Forming Residues (IFR). We were motivated to identify those amino acids with decreased accessibility to solvent after docking of different types of inhibitors to sub classes of serine proteases and then create a table (matrix) of all amino acid positions at the interface as well as their respective occupancies. Our goal is to establish a platform for analysis of the relationship between IFR characteristics and binding properties/specificity for bi-molecular complexes. We propose a novel method for describing binding properties and delineating serine proteases specificity by compiling an exhaustive table of interface forming residues (IFR) for serine proteases and their inhibitors. Currently, the Protein Data Bank (PDB) does not contain all the data that our analysis would require. Therefore, an in silico approach was designed for building corresponding complexes. The IFRs are obtained by "rigid body docking" among 70 structurally aligned, sequence wise non-redundant, serine protease structures with 3 inhibitors: bovine pancreatic trypsin inhibitor (BPTI), ecotine and ovomucoid third domain inhibitor. The table (matrix) of all amino acid positions at the interface and their respective occupancy is created. We also developed a new computational protocol for predicting IFRs for those complexes which were not deciphered experimentally so far, achieving accuracy of at least 0.97. The serine proteases interfaces prefer polar (including glycine) residues (with some exceptions). Charged residues were found to be uniquely prevalent at the interfaces between the "miscellaneous-virus" subfamily

2D-HB-Network at the air-water interface: A structural and dynamical characterization by means of ab initio and classical molecular dynamics simulations

Science.gov (United States)

Pezzotti, Simone; Serva, Alessandra; Gaigeot, Marie-Pierre

2018-05-01

Following our previous work where the existence of a special 2-Dimensional H-Bond (2D-HB)-Network was revealed at the air-water interface [S. Pezzotti et al., J. Phys. Chem. Lett. 8, 3133 (2017)], we provide here a full structural and dynamical characterization of this specific arrangement by means of both Density Functional Theory based and Force Field based molecular dynamics simulations. We show in particular that water at the interface with air reconstructs to maximize H-Bonds formed between interfacial molecules, which leads to the formation of an extended and non-interrupted 2-Dimensional H-Bond structure involving on average ˜90% of water molecules at the interface. We also show that the existence of such an extended structure, composed of H-Bonds all oriented parallel to the surface, constrains the reorientional dynamics of water that is hence slower at the interface than in the bulk. The structure and dynamics of the 2D-HB-Network provide new elements to possibly rationalize several specific properties of the air-water interface, such as water surface tension, anisotropic reorientation of interfacial water under an external field, and proton hopping.

Network Interface Specification for the T1 Microprocessor

Science.gov (United States)

1994-05-01

details of the data transfer functional units, interconnect structure, and network operation. Application Layer Communication Model Communication...use of the communication resources. 3.6 Network Virtualisation The CNS-1 is designed for single-user, batch-style processing; no timesharing or space...matches the count register (both the timer and count register are in the network interface and are user-accessible). Although this function is not strictly

Topology optimization of coated structures and material interface problems

DEFF Research Database (Denmark)

Clausen, Anders; Aage, Niels; Sigmund, Ole

2015-01-01

This paper presents a novel method for including coated structures and prescribed material interface properties into the minimum compliance topology optimization problem. Several elements of the method are applicable to a broader range of interface problems. The approach extends the standard SIMP......-step filtering/projection approach. The modeled coating thickness is derived analytically, and the coating is shown to be accurately controlled and applied in a highly uniform manner over the structure. An alternative interpretation of the model is to perform single-material design for additive manufacturing...

Magnetic structure of the spin valve interface

International Nuclear Information System (INIS)

Nicholson, D.M.C.; Butler, W.H.; Zhang, X.; MacLaren, J.M.; Gurney, B.A.; Speriosu, V.S.

1994-01-01

Nonferromagnetic atoms present at Ni/Cu and Permalloy/Cu interfaces in sputtered spin valve magnetoresistive layered structures have been shown to cause reduced magnetoresistance. Here we show that a model in which the moments on the Ni atoms in the interfacial region of Ni/Cu are reduced substantially by interdiffusion with Cu is consistent with the experimental results. In contrast, we believe that moments persist at the permalloy/Cu interface, which first principle total energy calculations suggest will be disordered at finite temperatures. These reduced or disordered moments are expected to significantly reduce the GMR

A structural approach to constructing perspective efficient and reliable human-computer interfaces

International Nuclear Information System (INIS)

Balint, L.

1989-01-01

The principles of human-computer interface (HCI) realizations are investigated with the aim of getting closer to a general framework and thus, to a more or less solid background of constructing perspective efficient, reliable and cost-effective human-computer interfaces. On the basis of characterizing and classifying the different HCI solutions, the fundamental problems of interface construction are pointed out especially with respect to human error occurrence possibilities. The evolution of HCI realizations is illustrated by summarizing the main properties of past, present and foreseeable future interface generations. HCI modeling is pointed out to be a crucial problem in theoretical and practical investigations. Suggestions concerning HCI structure (hierarchy and modularity), HCI functional dynamics (mapping from input to output information), minimization of human error caused system failures (error-tolerance, error-recovery and error-correcting) as well as cost-effective HCI design and realization methodology (universal and application-oriented vs. application-specific solutions) are presented. The concept of RISC-based and SCAMP-type HCI components is introduced with the aim of having a reduced interaction scheme in communication and a well defined architecture in HCI components' internal structure. HCI efficiency and reliability are dealt with, by taking into account complexity and flexibility. The application of fast computerized prototyping is also briefly investigated as an experimental device of achieving simple, parametrized, invariant HCI models. Finally, a concise outline of an approach of how to construct ideal HCI's is also suggested by emphasizing the open questions and the need of future work related to the proposals, as well. (author). 14 refs, 6 figs

Modality-Specific Axonal Regeneration: Towards selective regenerative neural interfaces

Directory of Open Access Journals (Sweden)

Parisa eLotfi

2011-10-01

Full Text Available Regenerative peripheral nerve interfaces have been proposed as viable alternatives for the natural control of robotic prosthetic devices. However, sensory and motor axons at the neural interface are of mixed submodality types, which difficult the specific recording from motor axons and the eliciting of precise sensory modalities through selective stimulation. Here we evaluated the possibility of using type-specific neurotrophins to preferentially entice the regeneration of defined axonal populations from transected peripheral nerves into separate compartments. Segregation of mixed sensory fibers from dorsal root ganglion neurons was evaluated in vitro by compartmentalized diffusion delivery of nerve growth factor (NGF and neurotrophin-3 (NT-3, to preferentially entice the growth of TrkA+ nociceptive and TrkC+ proprioceptive subsets of sensory neurons, respectively. The average axon length in the NGF channel increased 2.5 fold compared to that in saline or NT-3, whereas the number of branches increased 3 fold in the NT-3 channels. These results were confirmed using a 3-D Y-shaped in vitro assay showing that the arm containing NGF was able to entice a 5-fold increase in axonal length of unbranched fibers. To address if such segregation can be enticed in vivo, a Y-shaped tubing was used to allow regeneration of the transected adult rat sciatic nerve into separate compartments filled with either NFG or NT-3. A significant increase in the number of CGRP+ pain fibers were attracted towards the sural nerve, while N-52+ large diameter axons were observed in the tibial and NT-3 compartments. This study demonstrates the guided enrichment of sensory axons in specific regenerative chambers, and supports the notion that neurotrophic factors can be used to segregate sensory and perhaps motor axons in separate peripheral interfaces.

Structural and phonon transmission study of Ge-Au-Ge eutectically bonded interfaces

International Nuclear Information System (INIS)

Knowlton, W.B.; Lawrence Berkeley Lab., CA

1995-07-01

This thesis presents a structural analysis and phonon transparency investigation of the Ge-Au-Ge eutectic bond interface. Interface development was intended to maximize the interfacial ballistic phonon transparency to enhance the detection of the dark matter candidate WIMPs. The process which was developed provides an interface which produces minimal stress, low amounts of impurities, and insures Ge lattice continuity through the interface. For initial Au thicknesses of greater than 1,000 angstrom Au per substrate side, eutectic epitaxial growth resulted in a Au dendritic structure with 95% cross sectional and 90% planar Au interfacial area coverages. In sections in which Ge bridged the interface, lattice continuity across the interface was apparent. Epitaxial solidification of the eutectic interface with initial Au thicknesses < 500 A per substrate side produced Au agglomerations thereby reducing the Au planar interfacial area coverage to as little as 30%. The mechanism for Au coalescence was attributed to lateral diffusion of Ge and Au in the liquid phase during solidification. Phonon transmission studies were performed on eutectic interfaces with initial Au thicknesses of 1,000 angstrom, 500 angstrom, and 300 angstrom per substrate side. Phonon imaging of eutectically bonded samples with initial Au thicknesses of 300 angstrom/side revealed reproducible interfacial percent phonon transmissions from 60% to 70%. Line scan phonon imaging verified the results. Phonon propagation TOF spectra distinctly showed the predominant phonon propagation mode was ballistic. This was substantiated by phonon focusing effects apparent in the phonon imaging data. The degree of interface transparency to phonons and resulting phonon propagation modes correlate with the structure of the interface following eutectic solidification. Structural studies of samples with initial Au thickness of 1,000 angstrom/side appear to correspond with the phonon transmission study

Structural and phonon transmission study of Ge-Au-Ge eutectically bonded interfaces

Energy Technology Data Exchange (ETDEWEB)

Knowlton, W.B. [Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering]|[Lawrence Berkeley Lab., CA (United States). Materials Sciences Div.

1995-07-01

This thesis presents a structural analysis and phonon transparency investigation of the Ge-Au-Ge eutectic bond interface. Interface development was intended to maximize the interfacial ballistic phonon transparency to enhance the detection of the dark matter candidate WIMPs. The process which was developed provides an interface which produces minimal stress, low amounts of impurities, and insures Ge lattice continuity through the interface. For initial Au thicknesses of greater than 1,000 {angstrom} Au per substrate side, eutectic epitaxial growth resulted in a Au dendritic structure with 95% cross sectional and 90% planar Au interfacial area coverages. In sections in which Ge bridged the interface, lattice continuity across the interface was apparent. Epitaxial solidification of the eutectic interface with initial Au thicknesses < 500 A per substrate side produced Au agglomerations thereby reducing the Au planar interfacial area coverage to as little as 30%. The mechanism for Au coalescence was attributed to lateral diffusion of Ge and Au in the liquid phase during solidification. Phonon transmission studies were performed on eutectic interfaces with initial Au thicknesses of 1,000 {angstrom}, 500 {angstrom}, and 300 {angstrom} per substrate side. Phonon imaging of eutectically bonded samples with initial Au thicknesses of 300 {angstrom}/side revealed reproducible interfacial percent phonon transmissions from 60% to 70%. Line scan phonon imaging verified the results. Phonon propagation TOF spectra distinctly showed the predominant phonon propagation mode was ballistic. This was substantiated by phonon focusing effects apparent in the phonon imaging data. The degree of interface transparency to phonons and resulting phonon propagation modes correlate with the structure of the interface following eutectic solidification. Structural studies of samples with initial Au thickness of 1,000 {angstrom}/side appear to correspond with the phonon transmission study.

PRince: a web server for structural and physicochemical analysis of protein-RNA interface.

Science.gov (United States)

Barik, Amita; Mishra, Abhishek; Bahadur, Ranjit Prasad

2012-07-01

We have developed a web server, PRince, which analyzes the structural features and physicochemical properties of the protein-RNA interface. Users need to submit a PDB file containing the atomic coordinates of both the protein and the RNA molecules in complex form (in '.pdb' format). They should also mention the chain identifiers of interacting protein and RNA molecules. The size of the protein-RNA interface is estimated by measuring the solvent accessible surface area buried in contact. For a given protein-RNA complex, PRince calculates structural, physicochemical and hydration properties of the interacting surfaces. All these parameters generated by the server are presented in a tabular format. The interacting surfaces can also be visualized with software plug-in like Jmol. In addition, the output files containing the list of the atomic coordinates of the interacting protein, RNA and interface water molecules can be downloaded. The parameters generated by PRince are novel, and users can correlate them with the experimentally determined biophysical and biochemical parameters for better understanding the specificity of the protein-RNA recognition process. This server will be continuously upgraded to include more parameters. PRince is publicly accessible and free for use. Available at http://www.facweb.iitkgp.ernet.in/~rbahadur/prince/home.html.

Molecular orientation and electronic structure at organic heterojunction interfaces

Energy Technology Data Exchange (ETDEWEB)

Zhong, Shu [Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 Singapore (Singapore); Zhong, Jian Qiang; Wee, Andrew T.S. [Department of Physics, National University of Singapore, 2 Science Drive 3, 117542 Singapore (Singapore); Chen, Wei, E-mail: phycw@nus.edu.sg [Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 Singapore (Singapore); Department of Physics, National University of Singapore, 2 Science Drive 3, 117542 Singapore (Singapore); National University of Singapore (Suzhou) Research Institute, Suzhou (China)

2015-10-01

Highlights: • Molecular orientation at the organic heterojunction interfaces. • Energy level alignments at the organic heterojunction interfaces. • Gap-states mediated interfacial energy level alignment. - Abstract: Due to the highly anisotropic nature of π-conjugated molecules, the molecular orientation in organic thin films can significantly affect light absorption, charge transport, energy level alignment (ELA) and hence device performance. Synchrotron-based near-edge X-ray absorption fine structure (NEXAFS) spectroscopy represents a powerful technique for probing molecular orientation. The aim of this review paper is to provide a balanced assessment on the investigation of molecular orientation at the organic–organic heterojunction (OOH) interface by NEXAFS, as well as the gap-states mediated orientation dependent energy level alignment at OOH interfaces. We highlight recent progress in elucidating molecular orientation at OOH interfaces dominated by various interfacial interactions, gap-states controlled orientation dependent energy level alignments at OOH interfaces, and the manipulations of molecular orientation and ELA in OOH.

Mechanical properties along interfaces of bonded structures in fusion reactors

International Nuclear Information System (INIS)

Hassan, M.H.; Kulcinski, G.L.

1993-01-01

Proper assessment of the mechanical properties along interfaces of bonded structures currently used in many fusion reactor designs is essential to compare the different fabrication techniques. A Mechanical Properties Microprobe (MPM) was used to measure hardness and Young's modules along the interfaces of Be/Cu bonded structure. The MPM was able to distinguish different fabrication techniques by a direct measurement of the hardness, Young's modules, and H/E 2 which reflects the ability of deformation of the interfacial region

Structural insights into Rhino-Deadlock complex for germline piRNA cluster specification.

Science.gov (United States)

Yu, Bowen; Lin, Yu An; Parhad, Swapnil S; Jin, Zhaohui; Ma, Jinbiao; Theurkauf, William E; Zhang, Zz Zhao; Huang, Ying

2018-06-01

PIWI-interacting RNAs (piRNAs) silence transposons in germ cells to maintain genome stability and animal fertility. Rhino, a rapidly evolving heterochromatin protein 1 (HP1) family protein, binds Deadlock in a species-specific manner and so defines the piRNA-producing loci in the Drosophila genome. Here, we determine the crystal structures of Rhino-Deadlock complex in Drosophila melanogaster and simulans In both species, one Rhino binds the N-terminal helix-hairpin-helix motif of one Deadlock protein through a novel interface formed by the beta-sheet in the Rhino chromoshadow domain. Disrupting the interface leads to infertility and transposon hyperactivation in flies. Our structural and functional experiments indicate that electrostatic repulsion at the interaction interface causes cross-species incompatibility between the sibling species. By determining the molecular architecture of this piRNA-producing machinery, we discover a novel HP1-partner interacting mode that is crucial to piRNA biogenesis and transposon silencing. We thus explain the cross-species incompatibility of two sibling species at the molecular level. © 2018 The Authors.

Molecular dynamics study of structure and vibrational spectra at zwitterionoic lipid/aqueous KCl, NaCl, and CaCl2 solution interfaces

Science.gov (United States)

Ishiyama, Tatsuya; Shirai, Shinnosuke; Okumura, Tomoaki; Morita, Akihiro

2018-06-01

Molecular dynamics (MD) simulations of KCl, NaCl, and CaCl2 solution/dipalmytoylphosphatidylcholine lipid interfaces were performed to analyze heterodyne-detected vibrational sum frequency generation (HD-VSFG) spectra in relation to the interfacial water structure. The present MD simulation well reproduces the experimental spectra and elucidates a specific cation effect on the interfacial structure. The K+, Na+, and Ca2+ cation species penetrate in the lipid layer more than the anions in this order, due to the electrostatic interaction with negative polar groups of lipid, and the electric double layer between the cations and anions cancels the intrinsic orientation of water at the water/lipid interface. These mechanisms explain the HD-VSFG spectrum of the water/lipid interface and its spectral perturbation by adding the ions. The lipid monolayer reverses the order of surface preference of the cations at the solution/lipid interface from that at the solution/air interface.

Predicting nucleic acid binding interfaces from structural models of proteins.

Science.gov (United States)

Dror, Iris; Shazman, Shula; Mukherjee, Srayanta; Zhang, Yang; Glaser, Fabian; Mandel-Gutfreund, Yael

2012-02-01

The function of DNA- and RNA-binding proteins can be inferred from the characterization and accurate prediction of their binding interfaces. However, the main pitfall of various structure-based methods for predicting nucleic acid binding function is that they are all limited to a relatively small number of proteins for which high-resolution three-dimensional structures are available. In this study, we developed a pipeline for extracting functional electrostatic patches from surfaces of protein structural models, obtained using the I-TASSER protein structure predictor. The largest positive patches are extracted from the protein surface using the patchfinder algorithm. We show that functional electrostatic patches extracted from an ensemble of structural models highly overlap the patches extracted from high-resolution structures. Furthermore, by testing our pipeline on a set of 55 known nucleic acid binding proteins for which I-TASSER produces high-quality models, we show that the method accurately identifies the nucleic acids binding interface on structural models of proteins. Employing a combined patch approach we show that patches extracted from an ensemble of models better predicts the real nucleic acid binding interfaces compared with patches extracted from independent models. Overall, these results suggest that combining information from a collection of low-resolution structural models could be a valuable approach for functional annotation. We suggest that our method will be further applicable for predicting other functional surfaces of proteins with unknown structure. Copyright © 2011 Wiley Periodicals, Inc.

Modification of surface/neuron interfaces for neural cell-type specific responses: a review

International Nuclear Information System (INIS)

Chen, Cen; Kong, Xiangdong; Lee, In-Seop

2016-01-01

Surface/neuron interfaces have played an important role in neural repair including neural prostheses and tissue engineered scaffolds. This comprehensive literature review covers recent studies on the modification of surface/neuron interfaces. These interfaces are identified in cases both where the surfaces of substrates or scaffolds were in direct contact with cells and where the surfaces were modified to facilitate cell adhesion and controlling cell-type specific responses. Different sources of cells for neural repair are described, such as pheochromocytoma neuronal-like cell, neural stem cell (NSC), embryonic stem cell (ESC), mesenchymal stem cell (MSC) and induced pluripotent stem cell (iPS). Commonly modified methods are discussed including patterned surfaces at micro- or nano-scale, surface modification with conducting coatings, and functionalized surfaces with immobilized bioactive molecules. These approaches to control cell-type specific responses have enormous potential implications in neural repair. (paper)

Effect of impurities on structural and electrochemical properties of the Ni-YSZ interface

DEFF Research Database (Denmark)

Jensen, Karin Vels; Wallenberg, R.; Chorkendorff, I.

2003-01-01

. The results were compared to earlier investigations of a less pure nickel/YSZ interface. The pure interface developed different structures depending on whether or not the samples were polarised. Despite,the purity of the nickel, impurities were found in the interfacial region. The pure electrodes......The changes in interface structure and chemical composition of a 99.995% pure nickel/yttria-stabilised zirconia (YSZ) interface were examined after heat treatment at 1000degreesC in 97% H-2/3% H2O with and without polarisation. Impedance spectroscopy was used for electrochemical characterisation...

Electronic structure of ferromagnet-insulator interfaces: Fe/MgO and Co/MgO

Energy Technology Data Exchange (ETDEWEB)

Mueller, M.

2007-07-11

In this thesis the electronic structure of Fe/MgO{sub x} and Co/MgO{sub x} ferromagnet-insulator interfaces, representing material systems which are widely used in magnetic tunnel junctions, is studied by means of spin- and angle-resolved photoemission spectroscopy. The photoemission studies focus particularly on the response of the ferromagnetic electronic system in contact with MgO of varying stoichiometries, as this reflects the mechanisms of metal-oxide bonding at real ferromagnet-insulator interfaces. The correlation between chemical bonding and electronic structure formation is analyzed by combining information from core- and valence-band photoemission spectroscopy. The spectral features are compared to band structure calculations, which are performed using the SPR-KKR method. The Fe/MgO and Co/MgO systems are prepared by molecular beam epitaxy under ultrahigh vacuum conditions on well-defined (4 x 6) GaAs(001) substrates. A structural analysis by means of low-energy electron diffraction (LEED) reveals their body-centered cubic crystalline structure, whereas the chemical characterization by Auger electron spectroscopy is used to quantify the chemical environment at the sample surfaces. The magnetic analysis, using the magneto-optical Kerr effect, reveals the uniaxial anisotropy of the ferromagnetic layers. A crucial parameter is given by the MgO degree of oxidation, which is addressed by means of core-level spectroscopy and quantified by suitable fitting procedures of the Mg 2p core level. The results of the photoemission experiments show, that the electronic structure of the Fe/MgO and Co/MgO ferromagnet/insulator interfaces and, consequently, the interfacial spin polarization are sensitively controlled by the interface chemistry. In particular, three distinct scenarios are identified: the nearly stoichiometric, the oxygen-deficient and the over-oxidized ferromagnet/MgO interface. Each case is defined by innate characteristics of the electronic structure at

Specific interface area in a thin layer system of two immiscible liquids with vapour generation at the contact interface

Science.gov (United States)

Pimenova, Anastasiya V.; Gazdaliev, Ilias M.; Goldobin, Denis S.

2017-06-01

For well-stirred multiphase fluid systems the mean interface area per unit volume, or “specific interface area” SV, is a significant characteristic of the system state. In particular, it is important for the dynamics of systems of immiscible liquids experiencing interfacial boiling. We estimate the value of parameter SV as a function of the heat influx {\\dot{Q}}V to the system or the average system overheat above the interfacial boiling point. The derived results can be reformulated for the case of an endothermic chemical reaction between two liquid reagents with the gaseous form of one of the reaction products. The final results are restricted to the case of thin layers, where the potential gravitational energy of bubbles leaving the contact interface is small compared to their surface tension energy.

Atomic structures and compositions of internal interfaces

Energy Technology Data Exchange (ETDEWEB)

Seidman, D.N. (Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering); Merkle, K.L. (Argonne National Lab., IL (United States))

1992-03-01

This research program addresses fundamental questions concerning the relationships between atomic structures and chemical compositions of metal/ceramic heterophase interfaces. The chemical composition profile across a Cu/MgO {l brace}111{r brace}-type heterophase interface, produced by the internal oxidation of a Cu(Mg) single phase alloy, is measured via atom-probe field-ion microscopy with a spatial resolution of 0.121 nm; this resolution is equal to the interplanar space of the {l brace}222{r brace} MgO planes. In particular, we demonstrate for the first time that the bonding across a Cu/MgO {l brace}111{r brace}-type heterophase interface, along a <111> direction common to both the Cu matrix and an MgO precipitate, has the sequence Cu{vert bar}O{vert bar}Mg{hor ellipsis} and not Cu{vert bar}Mg{vert bar}O{hor ellipsis}; this result is achieved without any deconvolution of the experimental data. Before determining this chemical sequence it was established, via high resolution electron microscopy, that the morphology of an MgO precipitate in a Cu matrix is an octahedron faceted on {l brace}111{r brace} planes with a cube-on-cube relationship between a precipitate and the matrix. First results are also presented for the Ni/Cr{sub 2}O{sub 4} interface; for this system selected area atom probe microscopy was used to analyze this interface; Cr{sub 2}O{sub 4} precipitates are located in a field-ion microscope tip and a precipitate is brought into the tip region via a highly controlled electropolishing technique.

Electronic structure and STM imaging of the KBr-InSb interface

Energy Technology Data Exchange (ETDEWEB)

Ciochoń, Piotr, E-mail: ciochon.piotr@gmail.com; Olszowska, Natalia; Kołodziej, Jacek J.

2017-07-01

Highlights: • The structure of the InSb (001) surface covered with thin KBr layers is reported. • KBr growth does not perturb strongly the structure of a clean InSb surface. • A model of the system with KBr treated as a thin dielectric layer is proposed. • The atomic structure of the KBr-InSb interface is directly imaged using STM. - Abstract: We study the properties of the InSb (001) surface covered with ultrathin KBr films, with a thickness of 1–4 ML. KBr deposition does not strongly perturb the crystallographic structure of the InSb surface and the electronic structure of the substrate also remains unaffected by the overlayer. A simple model of the studied system is proposed, in which a thin KBr layer is treated as a dielectric film, modifying potential barrier for the electrons tunneling to/from the InSb substrate. Apparent step heights on the KBr film, measured using scanning tunneling microscope (STM), agree well with the predictions of the model and the atomically-resolved STM images show the structure of the InSb-KBr interface. Our results demonstrate that STM may be used as a tool for investigations of the semiconductor–insulator interfaces.

How NASA KSC Controls Interfaces with the use of Motion Skeletons and Product Structure

Science.gov (United States)

Jones, Corey

2013-01-01

This presentation will show how NASA KSC controls interfaces for Modular Product Architecture (MPA) using Locator Skeletons, Interface Skeletons, and Product Structure, to be combined together within a Motion Skeleton. The user will learn how to utilize skeleton models to communicate interface data, as successfully done at NASA KSC in their use of Motion Skeletons to control interfaces for multi-launch systems. There will be discussion of the methodology used to control design requirements through WTParts, and how to utilize product structure for non-CAD documents.

Toward Smart Aerospace Structures: Design of a Piezoelectric Sensor and Its Analog Interface for Flaw Detection

Science.gov (United States)

Boukabache, Hamza; Escriba, Christophe; Fourniols, Jean-Yves

2014-01-01

Structural health monitoring using noninvasive methods is one of the major challenges that aerospace manufacturers face in this decade. Our work in this field focuses on the development and the system integration of millimetric piezoelectric sensors/ actuators to generate and measure specific guided waves. The aim of the application is to detect mechanical flaws on complex composite and alloy structures to quantify efficiently the global structures' reliability. The study begins by a physical and analytical analysis of a piezoelectric patch. To preserve the structure's integrity, the transducers are directly pasted onto the surface which leads to a critical issue concerning the interfacing layer. In order to improve the reliability and mitigate the influence of the interfacing layer, the global equations of piezoelectricity are coupled with a load transfer model. Thus we can determine precisely the shear strain developed on the surface of the structure. To exploit the generated signal, a high precision analog charge amplifier coupled to a double T notch filter were designed and scaled. Finally, a novel joined time-frequency analysis based on a wavelet decomposition algorithm is used to extract relevant structures signatures. Finally, this paper provides examples of application on aircraft structure specimens and the feasibility of the system is thus demonstrated. PMID:25365457

Toward smart aerospace structures: design of a piezoelectric sensor and its analog interface for flaw detection.

Science.gov (United States)

Boukabache, Hamza; Escriba, Christophe; Fourniols, Jean-Yves

2014-10-31

Structural health monitoring using noninvasive methods is one of the major challenges that aerospace manufacturers face in this decade. Our work in this field focuses on the development and the system integration of millimetric piezoelectric sensors/ actuators to generate and measure specific guided waves. The aim of the application is to detect mechanical flaws on complex composite and alloy structures to quantify efficiently the global structures' reliability. The study begins by a physical and analytical analysis of a piezoelectric patch. To preserve the structure's integrity, the transducers are directly pasted onto the surface which leads to a critical issue concerning the interfacing layer. In order to improve the reliability and mitigate the influence of the interfacing layer, the global equations of piezoelectricity are coupled with a load transfer model. Thus we can determine precisely the shear strain developed on the surface of the structure. To exploit the generated signal, a high precision analog charge amplifier coupled to a double T notch filter were designed and scaled. Finally, a novel joined time-frequency analysis based on a wavelet decomposition algorithm is used to extract relevant structures signatures. Finally, this paper provides examples of application on aircraft structure specimens and the feasibility of the system is thus demonstrated.

Structure and chemical composition of layers adsorbed at interfaces with champagne.

Science.gov (United States)

Aguié-Béghin, V; Adriaensen, Y; Péron, N; Valade, M; Rouxhet, P; Douillard, R

2009-11-11

The structure and the chemical composition of the layer adsorbed at interfaces involving champagne have been investigated using native champagne, as well as ultrafiltrate (UFch) and ultraconcentrate (UCch) obtained by ultrafiltration with a 10(4) nominal molar mass cutoff. The layer adsorbed at the air/liquid interface was examined by surface tension and ellipsometry kinetic measurements. Brewster angle microscopy demonstrated that the layer formed on polystyrene by adsorption or drop evaporation was heterogeneous, with a domain structure presenting similarities with the layer adsorbed at the air/liquid interface. The surface chemical composition of polystyrene with the adlayer was determined by X-ray photoelectron spectroscopy (XPS). The contribution of champagne constituents varied according to the liquid (native, UFch, and UCch) and to the procedure of adlayer formation (evaporation, adsorption, and adsorption + rinsing). However, their chemical composition was not significantly influenced either by ultrafiltration or by the procedure of deposition on polystyrene. Modeling this composition in terms of classes of model compounds gave approximately 35% (w/w) of proteins and 65% (w/w) of polysaccharides. In the adlayer, the carboxyl groups or esters represent about 18% of carbon due to nonpolypeptidic compounds, indicating the presence of either uronic acids in the complex structure of pectic polysaccharides or of polyphenolic esters. This structural and chemical information and its relationship with the experimental procedures indicate that proteins alone cannot be used as a realistic model for the macromolecules forming the adsorption layer of champagne. Polysaccharides, the other major macromolecular components of champagne wine, are assembled with proteins at the interfaces, in agreement with the heterogeneous character of the adsorbed layer at interfaces.

Cohesion strength and atomic structure of W-Cu graded interfaces

Energy Technology Data Exchange (ETDEWEB)

Liang, C.P.; Fan, J.L.; Gong, H.R., E-mail: gonghr@csu.edu.cn

2017-04-15

W-Cu graded interface is a solution to big differences of properties between W and Cu, while the number and composition of graded layers in the literature are quite different. The present first principles calculation reveals that W-rich graded interfaces possess higher strength and lower interface energy than Cu-rich counterparts. It shows that the differences of thermal expansion and Young’s modulus between overlayer and substrate are decisive factors in the design of Cu-rich and W-rich graded interfaces, respectively. A graded structure of W{sub 8}Cu{sub 1}/W{sub 7}Cu{sub 2}/W{sub 6}Cu{sub 3}/Cu{sub 6}W{sub 3}/Cu{sub 8}W{sub 1} is therefore suggested theoretically.

Crystalline oxides on semiconductors: A structural transition of the interface phase

Science.gov (United States)

Walker, F. J.; Buongiorno-Nardelli, Marco; Billman, C. A.; McKee, R. A.

2004-03-01

The growth of crystalline oxides on silicon is facilitated by the preparation of a surface phase of alkaline earth silicide. We describe how the surface phase serves as a precursor of the final interface phase using reflection high energy electron diffraction (RHEED) and density functional theory (DFT). RHEED intensity oscillations of the growth of BaSrO show layer-by-layer build up of the oxide on the interface. The 2x1 symmetry of the surface precursor persists up to 3 ML BaSrO coverage at which point a 1x1 pattern characteristic of the rock-salt structure of BaSrO is observed. Prior to 3 ML growth of alkaline earth oxide, DFT calculations and RHEED show that the surface precursor persists as the interface phase and induces large displacements in the growing oxide layer away from the rock-salt structure and having a 2x1 symmetry. These distortions of the rock-salt structure are energetically unfavorable and become more unfavorable as the oxide thickness increases. At 3 ML, the stability of the rock-salt structure drives a structural transformation of the film and the interface phase to a structure that is distinct from the surface precursor. Research sponsored jointly by the Division of Materials Sciences and Engineering, Office of Basic Energy Sciences, U.S. Department of Energy at Oak Ridge National Laboratory under contract DE-AC05-00OR22725 with UT-Battelle, LLC and at the University of Tennessee under contract DE-FG02-01ER45937. Calculations have been performed on CCS supercomputers at Oak Ridge National Laboratory.

The structure of the solid-liquid interface: atomic size effect; La structure de l'interface solide-liquide: effet de taille atomique

Energy Technology Data Exchange (ETDEWEB)

Geysermans, P.; Pontikis, V. [Centre National de la Recherche Scientifique (CNRS), 94 - Vitry-sur-Seine (France). Centre d' Etudes de Chimie Metallurgique

2002-09-01

The atomic structure of the solid-liquid heterophase interface was investigated by using molecular dynamics. Two kinds of systems were studied; the first one was crystalline copper with (100) and (111) surface terminations in contact with liquid aluminium, while in the second one the interface was modelled by two systems in contact made of Lennard-Jones particles with different size ({sigma}) and energy ({epsilon}) parameters. We found that at the interface the liquid was layered whatever the crystallographic orientation of the surface. The layering of the liquid is still preserved when the ratio of particles sites ({chi}={sigma}{sub 1}/{sigma}{sub 2}) changes while an epitaxial relationship is always found between the crystal and the first liquid layer. The average density of the latter is closely related to the {chi} value. (authors)

Structure Transformation and Coherent Interface in Large Lattice-Mismatched Nanoscale Multilayers

Directory of Open Access Journals (Sweden)

J. Y. Xie

2013-01-01

Full Text Available Nanoscale Al/W multilayers were fabricated by DC magnetron sputtering and characterized by transmission electron microscopy and high-resolution electron microscopy. Despite the large lattice mismatch and significantly different lattice structures between Al and W, a structural transition from face-centered cubic to body-centered cubic in Al layers was observed when the individual layer thickness was reduced from 5 nm to 1 nm, forming coherent Al/W interfaces. For potential mechanisms underlying the observed structure transition and forming of coherent interfaces, it was suggested that the reduction of interfacial energy and high stresses induced by large lattice-mismatch play a crucial role.

Modulation of Bacillus thuringiensis Phosphatidylinositol-Specific Phospholipase C Activity by Mutations in the Putative Dimerization Interface

Energy Technology Data Exchange (ETDEWEB)

Shi, X.; Shao, C; Zhang, X; Zambonelli, C; Redfield, A; Head, J; Seaton, B; Roberts, M

2009-01-01

Cleavage of phosphatidylinositol (PI) to inositol 1,2-(cyclic)-phosphate (cIP) and cIP hydrolysis to inositol 1-phosphate by Bacillus thuringiensis phosphatidylinositol-specific phospholipase C are activated by the enzyme binding to phosphatidylcholine (PC) surfaces. Part of this reflects improved binding of the protein to interfaces. However, crystallographic analysis of an interfacially impaired phosphatidylinositol-specific phospholipase (W47A/W242A) suggested protein dimerization might occur on the membrane. In the W47A/W242A dimer, four tyrosine residues from one monomer interact with the same tyrosine cluster of the other, forming a tight dimer interface close to the membrane binding regions. We have constructed mutant proteins in which two or more of these tyrosine residues have been replaced with serine. Phospholipid binding and enzymatic activity of these mutants have been examined to assess the importance of these residues to enzyme function. Replacing two tyrosines had small effects on enzyme activity. However, removal of three or four tyrosine residues weakened PC binding and reduced PI cleavage by the enzyme as well as PC activation of cIP hydrolysis. Crystal structures of Y247S/Y251S in the absence and presence of myo-inositol as well as Y246S/Y247S/Y248S/Y251S indicate that both mutant proteins crystallized as monomers, were very similar to one another, and had no change in the active site region. Kinetic assays, lipid binding, and structural results indicate that either (i) a specific PC binding site, critical for vesicle activities and cIP activation, has been impaired, or (ii) the reduced dimerization potential for Y246S/Y247S/Y248S and Y246S/Y247S/Y248S/Y251S is responsible for their reduced catalytic activity in all assay systems.

Structures and electronics of buried and unburied semiconductor interfaces

International Nuclear Information System (INIS)

Kamiya, Itaru

2011-01-01

The structure of interfaces plays an important role in determining the electronic properties of semiconductor nanostructures. Here, such examples are shown and discussed using semiconductor nanostructures prepared by molecular beam epitaxy and colloidal synthesis.

Interface properties of Fe/MgO/Cu-phthalocyanine metal-insulator-organic semiconductor structures

International Nuclear Information System (INIS)

Lee, Nyunjong; Bae, Yujeong; Kim, Taehee; Ito, Eisuke; Hara, Masahiko

2014-01-01

Hybrid interface structures consisting of organic copper-phthalocyanine (CuPc) and ferromagnetic metal Fe(001) with and without a MgO(001) cover were investigated by using surface sensitive techniques of X-ray photoemission spectroscopy and ultraviolet photoemission spectroscopy. A systematic study of the energy level alignment at the interfaces was carried out. For the hybrid interfaces considered here, our results indicate that the insertion of an artificially-grown ultra-thin oxide layer MgO(001) can prevent Femi level pinning and induce a rather large interface dipole, thereby resulting in remarkable CuPc Fermi level shifts when the thickness of the CuPc film is less than 3 nm. This study provides a better understanding of spin filtering in MgO-based organic spin devices and a new way to alter the interface electronic structure of metal/organic semiconductor hybrid systems.

The interface of protein structure, protein biophysics, and molecular evolution

Science.gov (United States)

Liberles, David A; Teichmann, Sarah A; Bahar, Ivet; Bastolla, Ugo; Bloom, Jesse; Bornberg-Bauer, Erich; Colwell, Lucy J; de Koning, A P Jason; Dokholyan, Nikolay V; Echave, Julian; Elofsson, Arne; Gerloff, Dietlind L; Goldstein, Richard A; Grahnen, Johan A; Holder, Mark T; Lakner, Clemens; Lartillot, Nicholas; Lovell, Simon C; Naylor, Gavin; Perica, Tina; Pollock, David D; Pupko, Tal; Regan, Lynne; Roger, Andrew; Rubinstein, Nimrod; Shakhnovich, Eugene; Sjölander, Kimmen; Sunyaev, Shamil; Teufel, Ashley I; Thorne, Jeffrey L; Thornton, Joseph W; Weinreich, Daniel M; Whelan, Simon

2012-01-01

Abstract The interface of protein structural biology, protein biophysics, molecular evolution, and molecular population genetics forms the foundations for a mechanistic understanding of many aspects of protein biochemistry. Current efforts in interdisciplinary protein modeling are in their infancy and the state-of-the art of such models is described. Beyond the relationship between amino acid substitution and static protein structure, protein function, and corresponding organismal fitness, other considerations are also discussed. More complex mutational processes such as insertion and deletion and domain rearrangements and even circular permutations should be evaluated. The role of intrinsically disordered proteins is still controversial, but may be increasingly important to consider. Protein geometry and protein dynamics as a deviation from static considerations of protein structure are also important. Protein expression level is known to be a major determinant of evolutionary rate and several considerations including selection at the mRNA level and the role of interaction specificity are discussed. Lastly, the relationship between modeling and needed high-throughput experimental data as well as experimental examination of protein evolution using ancestral sequence resurrection and in vitro biochemistry are presented, towards an aim of ultimately generating better models for biological inference and prediction. PMID:22528593

Surgeon Design Interface for Patient-Specific Concentric Tube Robots.

Science.gov (United States)

Morimoto, Tania K; Greer, Joseph D; Hsieh, Michael H; Okamura, Allison M

2016-06-01

Concentric tube robots have potential for use in a wide variety of surgical procedures due to their small size, dexterity, and ability to move in highly curved paths. Unlike most existing clinical robots, the design of these robots can be developed and manufactured on a patient- and procedure-specific basis. The design of concentric tube robots typically requires significant computation and optimization, and it remains unclear how the surgeon should be involved. We propose to use a virtual reality-based design environment for surgeons to easily and intuitively visualize and design a set of concentric tube robots for a specific patient and procedure. In this paper, we describe a novel patient-specific design process in the context of the virtual reality interface. We also show a resulting concentric tube robot design, created by a pediatric urologist to access a kidney stone in a pediatric patient.

Solvent Extraction: Structure of the Liquid-Liquid Interface Containing a Diamide Ligand

Energy Technology Data Exchange (ETDEWEB)

Scoppola, Ernesto [Institut Laue-Langevin, 38000 Grenoble France; Institut de Chimie Séparative de Marcoule, UMR 5257 CEA/CNRS/ENSCM/Université Montpellier, 30207 Bagnols-sur-Cèze France; Watkins, Erik B. [Institut Laue-Langevin, 38000 Grenoble France; Materials Synthesis and Integrated Devices, Los Alamos National Laboratory, Los Alamos NM 87545 USA; Campbell, Richard A. [Institut Laue-Langevin, 38000 Grenoble France; Konovalov, Oleg [European Synchrotron Radiation Facility, 38430 Grenoble France; Girard, Luc [Institut de Chimie Séparative de Marcoule, UMR 5257 CEA/CNRS/ENSCM/Université Montpellier, 30207 Bagnols-sur-Cèze France; Dufrêche, Jean-Francois [Institut de Chimie Séparative de Marcoule, UMR 5257 CEA/CNRS/ENSCM/Université Montpellier, 30207 Bagnols-sur-Cèze France; Ferru, Geoffroy [Argonne National Labororatory, Lemont IL 60439 USA; Fragneto, Giovanna [Institut Laue-Langevin, 38000 Grenoble France; Diat, Olivier [Institut de Chimie Séparative de Marcoule, UMR 5257 CEA/CNRS/ENSCM/Université Montpellier, 30207 Bagnols-sur-Cèze France

2016-06-20

Knowledge of the (supra)molecular structure of an interface that contains amphiphilic ligand molecules is necessary for a full understanding of ion transfer during solvent extraction. Even if molecular dynamics already yield some insight in the molecular configurations in solution, hardly any experimental data giving access to distributions of both extractant molecules and ions at the liquid–liquid interface exist. Here, the combined application of X-ray and neutron reflectivity measurements represents a key milestone in the deduction of the interfacial structure and potential with respect to two different lipophilic ligands. Indeed, we show for the first time that hard trivalent cations can be repelled or attracted by the extractant-enriched interface according to the nature of the ligand.

Role of wall-attached structures in the interface of the quiescent core region in turbulent pipe flow

Science.gov (United States)

Yang, Jongmin; Hwang, Jinyul; Sung, Hyung Jin

2017-11-01

The effects of low- and high-speed structures on the interface of the quiescent core region are explored using direct numerical simulation data of turbulent pipe flow. The quiescent core region is a uniform momentum zone located at the center of the pipe flow, which contains the highest streamwise momentum with a low level of turbulence. The interface of the quiescent core region can be identified from the probability density function of the streamwise modal velocity. In the vicinity of the interface of the quiescent core region, the streamwise velocity changes abruptly. The abrupt jump in velocity causes an increase of the velocity gradient. The interface of the quiescent core region is similar to the laminar superlayer in turbulent/non-turbulent interface. The interface of the quiescent core region contains the low- and high-speed structures. They can be classified into wall-attached and detached structures depending on the distance between the structures and the wall. The influence of the detached structures accounted for most of the number of detected structures is negligible due to its small volume. Conversely, the wall-attached structures adjacent to the interface have a huge influence on the statistical amount of the interface, such as entrainment characteristics. This work was supported by the Creative Research Initiatives (No. 2017-013369) program of the National Research Foundation of Korea (MSIP).

A standard format and a graphical user interface for spin system specification.

Science.gov (United States)

Biternas, A G; Charnock, G T P; Kuprov, Ilya

2014-03-01

We introduce a simple and general XML format for spin system description that is the result of extensive consultations within Magnetic Resonance community and unifies under one roof all major existing spin interaction specification conventions. The format is human-readable, easy to edit and easy to parse using standard XML libraries. We also describe a graphical user interface that was designed to facilitate construction and visualization of complicated spin systems. The interface is capable of generating input files for several popular spin dynamics simulation packages. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Interface structure and mechanics between graphene and metal substrates: a first-principles study

Science.gov (United States)

Xu, Zhiping; Buehler, Markus J.

2010-12-01

Graphene is a fascinating material not only for technological applications, but also as a test bed for fundamental insights into condensed matter physics due to its unique two-dimensional structure. One of the most intriguing issues is the understanding of the properties of graphene and various substrate materials. In particular, the interfaces between graphene and metal substrates are of critical importance in applications of graphene in integrated electronics, as thermal materials, and in electromechanical devices. Here we investigate the structure and mechanical interactions at a graphene-metal interface through density functional theory (DFT)-based calculations. We focus on copper (111) and nickel (111) surfaces adhered to a monolayer of graphene, and find that their cohesive energy, strength and electronic structure correlate directly with their atomic geometry. Due to the strong coupling between open d-orbitals, the nickel-graphene interface has a much stronger cohesive energy with graphene than copper. We also find that the interface cohesive energy profile features a well-and-shoulder shape that cannot be captured by simple pair-wise models such as the Lennard-Jones potential. Our results provide a detailed understanding of the interfacial properties of graphene-metal systems, and help to predict the performance of graphene-based nanoelectronics and nanocomposites. The availability of structural and energetic data of graphene-metal interfaces could also be useful for the development of empirical force fields for molecular dynamics simulations.

Toward Smart Aerospace Structures: Design of a Piezoelectric Sensor and Its Analog Interface for Flaw Detection

Directory of Open Access Journals (Sweden)

Hamza Boukabache

2014-10-01

Full Text Available Structural health monitoring using noninvasive methods is one of the major challenges that aerospace manufacturers face in this decade. Our work in this field focuses on the development and the system integration of millimetric piezoelectric sensors/ actuators to generate and measure specific guided waves. The aim of the application is to detect mechanical flaws on complex composite and alloy structures to quantify efficiently the global structures’ reliability. The study begins by a physical and analytical analysis of a piezoelectric patch. To preserve the structure’s integrity, the transducers are directly pasted onto the surface which leads to a critical issue concerning the interfacing layer. In order to improve the reliability and mitigate the influence of the interfacing layer, the global equations of piezoelectricity are coupled with a load transfer model. Thus we can determine precisely the shear strain developed on the surface of the structure. To exploit the generated signal, a high precision analog charge amplifier coupled to a double T notch filter were designed and scaled. Finally, a novel joined time-frequency analysis based on a wavelet decomposition algorithm is used to extract relevant structures signatures. Finally, this paper provides examples of application on aircraft structure specimens and the feasibility of the system is thus demonstrated.

The Ni-YSZ interface - Structure, composition and electrochemical properties at 1000 deg. C

Energy Technology Data Exchange (ETDEWEB)

Vels Jensen, Karin

2002-06-01

The anode/electrolyte interface in solid oxide fuel cells (SOFC) is known to cause electrical losses. Geometrically simple Ni/Yttria-stabilised zirconia (YSZ) interfaces were examined to gain information on the structural and chemical changes occurring during experiments at 1000 deg. C in an atmosphere of 97% H2/3% H{sub 2}O. Electrochemical impedance spectroscopy at open circuit voltage (OCV) and at anodic and cathodic polarisation (100 mV) was performed. A correlation of the electrical data with the structure development and the chemical composition was attempted. Nickel wires with different impurity content (99.8% Ni and 99.995% Ni) were used to examine the impact of impurities on the polarisation resistance and contact area morphology. The electro polished nickel wires were pressed against a polished 8 mol% YSZ surface. Extensive structural changes from a flat interface to a hill and valley structure were found to occur in the contact area with the impure nickel wire, and a ridge of impurities was built along the rim of the contact area. Impurity particles in the interfacial region were also observed. The impurity phase was described as an alkali silicate glassy phase. No differences were found between polarised and non-polarised samples. With pure nickel wires, however, the microstructures depended on the polarisation/non-polarisation conditions. At non-polarised conditions a hill and valley type structure was found. Anodic polarisation produced an up to 1 {mu}m thick interface layer consisting of nano-sized YSZ particles with some Ni present. At cathodic polarisation both a granulated structure and a hill and valley structure resembling the structure of non-polarised samples were found. Small impurity ridges were surrounding the contact areas on non-polarised and cathodically polarised samples. TOF-SIMS and XPS analyses showed the presence of impurities in both the impure and pure contact areas. The impedance spectroscopy revealed that depending on the

Structure characterization of Ni/NiO and Ti/TiO2 interfaces

International Nuclear Information System (INIS)

Lamine, Brahim

1983-01-01

This research thesis reports the structure characterization of Ni-NiO and Ti-TiO 2 interfaces through an in-situ investigation of thin blade oxidation, of oxide germination and growth, and through a determination of mutual metal/oxide orientation relationships. Thin films of TiO 2 have also been characterized and the study of the influence of vacuum annealing on TiO 2 layer structure and morphology has been attempted. The examination of metal-oxide interface reveals a duplex structure of NiO and TiO 2 layers, and a preferential grain boundary oxidation of the underlying metal [fr

Evaluation of underground pipe-structure interface for surface impact load

Energy Technology Data Exchange (ETDEWEB)

Wang, Shen, E-mail: swang@terrapower.com

2017-06-15

Highlights: • A simple method is proposed for the evaluation of underground pipelines for surface impact load considering the effect of a nearby pipe-structure interface. • The proposed simple method can be used to evaluate the magnitude of damage within a short period of time after accidental drop occurs. • The proposed method is applied in a practical example and compared by using finite element analysis. - Abstract: Nuclear safety related buried pipelines need to be assessed for the effects of postulated surface impact loads. In published solutions, the buried pipe is often considered within an elastic half space without interference with other underground structures. In the case that a surface impact occurs in short distance from an underground pipe-structure interface, this boundary condition will further complicate the buried pipe evaluation. Neglecting such boundary effect in the assessment may lead to underestimating potential damage of buried pipeline, and jeopardizing safety of the nuclear power plant. Comprehensive analysis of such structure-pipe-soil system is often subjected to availability of state-of-art finite element tools, as well as costly and time consuming. Simple, but practical conservative techniques have not been established. In this study, a mechanics based solution is proposed in order to assess the magnitude of damage to a buried pipeline beneath a heavy surface impact considering the effect of a nearby pipe-structure interface. The proposed approach provides an easy to use tool in the early stage of evaluation before the decision of applying more costly technique can be made by owner of the nuclear facility.

Evaluation of underground pipe-structure interface for surface impact load

International Nuclear Information System (INIS)

Wang, Shen

2017-01-01

Highlights: • A simple method is proposed for the evaluation of underground pipelines for surface impact load considering the effect of a nearby pipe-structure interface. • The proposed simple method can be used to evaluate the magnitude of damage within a short period of time after accidental drop occurs. • The proposed method is applied in a practical example and compared by using finite element analysis. - Abstract: Nuclear safety related buried pipelines need to be assessed for the effects of postulated surface impact loads. In published solutions, the buried pipe is often considered within an elastic half space without interference with other underground structures. In the case that a surface impact occurs in short distance from an underground pipe-structure interface, this boundary condition will further complicate the buried pipe evaluation. Neglecting such boundary effect in the assessment may lead to underestimating potential damage of buried pipeline, and jeopardizing safety of the nuclear power plant. Comprehensive analysis of such structure-pipe-soil system is often subjected to availability of state-of-art finite element tools, as well as costly and time consuming. Simple, but practical conservative techniques have not been established. In this study, a mechanics based solution is proposed in order to assess the magnitude of damage to a buried pipeline beneath a heavy surface impact considering the effect of a nearby pipe-structure interface. The proposed approach provides an easy to use tool in the early stage of evaluation before the decision of applying more costly technique can be made by owner of the nuclear facility.

Modeling of the atomic and electronic structures of interfaces

International Nuclear Information System (INIS)

Sutton, A.P.

1988-01-01

Recent tight binding and Car-Parrinello simulations of grain boundaries in semiconductors are reviewed. A critique is given of some models of embrittlement that are based on electronic structure considerations. The structural unit model of grain boundary structure is critically assessed using some results for mixed tilt and twist grain boundaries. A new method of characterizing interfacial structure in terms of bond angle distribution functions is described. A new formulation of thermodynamic properties of interfaces is presented which focusses on the local atomic environment. Effective, temperature dependent N-body atomic interactions are derived for studying grain boundary structure at elevated temperature

Evolutionary diversification of protein-protein interactions by interface add-ons.

Science.gov (United States)

Plach, Maximilian G; Semmelmann, Florian; Busch, Florian; Busch, Markus; Heizinger, Leonhard; Wysocki, Vicki H; Merkl, Rainer; Sterner, Reinhard

2017-10-03

Cells contain a multitude of protein complexes whose subunits interact with high specificity. However, the number of different protein folds and interface geometries found in nature is limited. This raises the question of how protein-protein interaction specificity is achieved on the structural level and how the formation of nonphysiological complexes is avoided. Here, we describe structural elements called interface add-ons that fulfill this function and elucidate their role for the diversification of protein-protein interactions during evolution. We identified interface add-ons in 10% of a representative set of bacterial, heteromeric protein complexes. The importance of interface add-ons for protein-protein interaction specificity is demonstrated by an exemplary experimental characterization of over 30 cognate and hybrid glutamine amidotransferase complexes in combination with comprehensive genetic profiling and protein design. Moreover, growth experiments showed that the lack of interface add-ons can lead to physiologically harmful cross-talk between essential biosynthetic pathways. In sum, our complementary in silico, in vitro, and in vivo analysis argues that interface add-ons are a practical and widespread evolutionary strategy to prevent the formation of nonphysiological complexes by specializing protein-protein interactions.

Direct observation of ionic structure at solid-liquid interfaces

DEFF Research Database (Denmark)

Siretanu, Igor; Ebeling, Daniel; Andersson, Martin Peter

2014-01-01

The distribution of ions and charge at solid-water interfaces plays an essential role in a wide range of processes in biology, geology and technology. While theoretical models of the solid-electrolyte interface date back to the early 20th century, a detailed picture of the structure of the electric...... double layer has remained elusive, largely because of experimental techniques have not allowed direct observation of the behaviour of ions, i.e. with subnanometer resolution. We have made use of recent advances in high-resolution Atomic Force Microscopy to reveal, with atomic level precision, the ordered...

Molecular Processes Underlying the Structure and Assembly of Thin Films and Nanoparticles at Complex interfaces

Energy Technology Data Exchange (ETDEWEB)

Richmond, Geraldine [Univ. of Oregon, Eugene, OR (United States)

2016-06-03

differences in how water behaves at hydrophobic self-assembled monolayer (SAMS)/water interfaces relative to the organic liquid/water interfaces. Several monolayer films have been examined in these studies using a combination of vibrational sum frequency spectroscopy (VSFS), contact angle measurements and AFM. At the hydrocarbon monolayer/water interface we find that water has a weak bonding interaction with the monolayer film that results in an orientation of water at the terminus of these hydrocarbon chains. The water-film interaction is still present for fluorinated films but it is found to be considerably weaker. Hydration and Surfactant Adsorption at Salt/Water Interfaces This set of studies has examined the molecular characteristics of the CaF₂/water interface using VSFS. Our first studies detailed the structure and orientation of water molecules adsorbed at this mineral surfaces including studies of the surface in the presence of aqueous solutions of salts. These studies have been followed by a series of static and time-resolved studies of the adsorption of carboxylic acid containing organics at this surface, specifically carboxylic acid surfactants and acetic acid. In the latter we have developed a new method for time resolved studies that involve sequential wavelength tuning and automated control of spatial beam overlap at the target can probe amplitude changes of sum-frequency resonances in widely spaced infrared regions. This offers great advantages for the study of the synchronism of molecular processes at interfaces. This approach is particularly suitable to investigate the synchronization of interfacial processes such as surfactant adsorption at charged mineral surfaces. Macromolecular Assembly at Liquid/Liquid Interfaces Macromolecular assembly at the interface between water and a hydrophobic surface underlies some of the most important biological and environmental processes on the planet. Our work has examined polymer adsorption and assembly of

Probing alpha-helical and beta-sheet structures of peptides at solid/liquid interfaces with SFG.

Science.gov (United States)

Chen, Xiaoyun; Wang, Jie; Sniadecki, Jason J; Even, Mark A; Chen, Zhan

2005-03-29

We demonstrated that sum frequency generation (SFG) vibrational spectroscopy can distinguish different secondary structures of proteins or peptides adsorbed at solid/liquid interfaces. The SFG spectrum for tachyplesin I at the polystyrene (PS)/solution interface has a fingerprint peak corresponding to the B1/B3 mode of the antiparallel beta-sheet. This peak disappeared upon the addition of dithiothreitol, which can disrupt the beta-sheet structure. The SFG spectrum indicative of the MSI594 alpha-helical structure was observed at the PS/MSI594 solution interface. This research validates SFG as a powerful technique for revealing detailed secondary structures of interfacial proteins and peptides.

Advanced understanding on electronic structure of molecular semiconductors and their interfaces

Science.gov (United States)

Akaike, Kouki

2018-03-01

Understanding the electronic structure of organic semiconductors and their interfaces is critical to optimizing functionalities for electronics applications, by rational chemical design and appropriate combination of device constituents. The unique electronic structure of a molecular solid is characterized as (i) anisotropic electrostatic fields that originate from molecular quadrupoles, (ii) interfacial energy-level lineup governed by simple electrostatics, and (iii) weak intermolecular interactions that make not only structural order but also energy distributions of the frontier orbitals sensitive to atmosphere and interface growth. This article shows an overview on these features with reference to the improved understanding of the orientation-dependent electronic structure, comprehensive mechanisms of molecular doping, and energy-level alignment. Furthermore, the engineering of ionization energy by the control of the electrostatic fields and work function of practical electrodes by contact-induced doping is briefly described for the purpose of highlighting how the electronic structure impacts the performance of organic devices.

Effects of interface edge configuration on residual stress in the bonded structures for a divertor application

International Nuclear Information System (INIS)

Kitamura, K.; Nagata, K.; Shibui, M.; Tachikawa, N.; Araki, M.

1998-01-01

Residual stresses in the interface region, that developed at the cool down during the brazing, were evaluated for several bonded structures to assess the mechanical strength of the bonded interface, using thermoelasto-plastic stress analysis. Normal stress components of the residual stresses around the interface edge of graphite-copper (C-Cu) bonded structures were compared for three types of bonded features such as flat-type, monoblock-type and saddle-type. The saddle-type structure was found to be favorable for its relatively low residual stress, easy fabrication accuracy on bonded interface and armor replacement. Residual stresses around the interface edge in three armor materials/copper bonded structures for a divertor plate were also examined for the C-Cu, tungsten-copper (W-Cu) and molybdenum alloy-copper (TZM-Cu), varying the interface wedge angle from 45 to 135 . An optimal bonded configuration for the least value of residual stress was found to have a wedge angle of 45 for the C-Cu, and 135 for both the W-Cu and TZM-Cu bonded ones. (orig.)

Organic/metal interfaces. Electronic and structural properties

Energy Technology Data Exchange (ETDEWEB)

Duhm, Steffen

2008-07-17

This work addresses several important topics of the field of organic electronics. The focus lies on organic/metal interfaces, which exist in all organic electronic devices. Physical properties of such interfaces are crucial for device performance. Four main topics have been covered: (i) the impact of molecular orientation on the energy levels, (ii) energy level tuning with strong electron acceptors, (iii) the role of thermodynamic equilibrium at organic/ organic homo-interfaces and (iv) the correlation of interfacial electronic structure and bonding distance. To address these issues a broad experimental approach was necessary: mainly ultraviolet photoelectron spectroscopy was used, supported by X-ray photoelectron spectroscopy, metastable atom electron spectroscopy, X-ray diffraction and X-ray standing waves, to examine vacuum sublimed thin films of conjugated organic molecules (COMs) in ultrahigh vacuum. (i) A novel approach is presented to explain the phenomenon that the ionization energy in molecular assemblies is orientation dependent. It is demonstrated that this is due to a macroscopic impact of intramolecular dipoles on the ionization energy in molecular assemblies. Furthermore, the correlation of molecular orientation and conformation has been studied in detail for COMs on various substrates. (ii) A new approach was developed to tune hole injection barriers ({delta}{sub h}) at organic/metal interfaces by adsorbing a (sub-) monolayer of an organic electron acceptor on the metal electrode. Charge transfer from the metal to the acceptor leads to a chemisorbed layer, which reduces {delta}{sub h} to the COM overlayer. This concept was tested with three acceptors and a lowering of {delta}{sub h} of up to 1.2 eV could be observed. (iii) A transition from vacuum-level alignment to molecular level pinning at the homo-interface between a lying monolayer and standing multilayers of a COM was observed, which depended on the amount of a pre-deposited acceptor. The

Effect of interface/surface stress on the elastic wave band structure of two-dimensional phononic crystals

International Nuclear Information System (INIS)

Liu, Wei; Chen, Jiwei; Liu, Yongquan; Su, Xianyue

2012-01-01

In the present Letter, the multiple scattering theory (MST) for calculating the elastic wave band structure of two-dimensional phononic crystals (PCs) is extended to include the interface/surface stress effect at the nanoscale. The interface/surface elasticity theory is employed to describe the nonclassical boundary conditions at the interface/surface and the elastic Mie scattering matrix embodying the interface/surface stress effect is derived. Using this extended MST, the authors investigate the interface/surface stress effect on the elastic wave band structure of two-dimensional PCs, which is demonstrated to be significant when the characteristic size reduces to nanometers. -- Highlights: ► Multiple scattering theory including the interface/surface stress effect. ► Interface/surface elasticity theory to describe the nonclassical boundary conditions. ► Elastic Mie scattering matrix embodying the interface/surface stress effect. ► Interface/surface stress effect would be significant at the nanoscale.

High fluence swift heavy ion structure modification of the SiO{sub 2}/Si interface and gate insulator in 65 nm MOSFETs

Energy Technology Data Exchange (ETDEWEB)

Ma, Yao [Key Laboratory of Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Key Lab of Microelectronics Sichuan Province, Sichuan University, Chengdu, Sichuan 610064 (China); College of Physical Science and Technology, Sichuan University, Chengdu, Sichuan 610064 (China); Gao, Bo, E-mail: gaobo@scu.edu.cn [Key Laboratory of Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Key Lab of Microelectronics Sichuan Province, Sichuan University, Chengdu, Sichuan 610064 (China); College of Physical Science and Technology, Sichuan University, Chengdu, Sichuan 610064 (China); Gong, Min [Key Laboratory of Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Key Lab of Microelectronics Sichuan Province, Sichuan University, Chengdu, Sichuan 610064 (China); College of Physical Science and Technology, Sichuan University, Chengdu, Sichuan 610064 (China); Willis, Maureen [College of Physical Science and Technology, Sichuan University, Chengdu, Sichuan 610064 (China); Yang, Zhimei [Key Laboratory of Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Key Lab of Microelectronics Sichuan Province, Sichuan University, Chengdu, Sichuan 610064 (China); Guan, Mingyue [College of Physical Science and Technology, Sichuan University, Chengdu, Sichuan 610064 (China); Li, Yun [Key Laboratory of Radiation Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Key Lab of Microelectronics Sichuan Province, Sichuan University, Chengdu, Sichuan 610064 (China); College of Physical Science and Technology, Sichuan University, Chengdu, Sichuan 610064 (China)

2017-04-01

In this work, a study of the structure modification, induced by high fluence swift heavy ion radiation, of the SiO{sub 2}/Si structures and gate oxide interface in commercial 65 nm MOSFETs is performed. A key and novel point in this study is the specific use of the transmission electron microscopy (TEM) technique instead of the conventional atomic force microscope (AFM) or scanning electron microscope (SEM) techniques which are typically performed following the chemical etching of the sample to observe the changes in the structure. Using this method we show that after radiation, the appearance of a clearly visible thin layer between the SiO{sub 2} and Si is observed presenting as a variation in the TEM intensity at the interface of the two materials. Through measuring the EDX line scans we reveal that the Si:O ratio changed and that this change can be attributed to the migration of the Si towards interface after the Si-O bond is destroyed by the swift heavy ions. For the 65 nm MOSFET sample, the silicon substrate, the SiON insulator and the poly-silicon gate interfaces become blurred under the same irradiation conditions.

Lattice structures and electronic properties of MO/MoSe2 interface from first-principles calculations

Science.gov (United States)

Zhang, Yu; Tang, Fu-Ling; Xue, Hong-Tao; Lu, Wen-Jiang; Liu, Jiang-Fei; Huang, Min

2015-02-01

Using first-principles plane-wave calculations within density functional theory, we theoretically studied the atomic structure, bonding energy and electronic properties of the perfect Mo (110)/MoSe2 (100) interface with a lattice mismatch less than 4.2%. Compared with the perfect structure, the interface is somewhat relaxed, and its atomic positions and bond lengths change slightly. The calculated interface bonding energy is about -1.2 J/m2, indicating that this interface is very stable. The MoSe2 layer on the interface has some interface states near the Fermi level, the interface states are mainly caused by Mo 4d orbitals, while the Se atom almost have no contribution. On the interface, Mo-5s and Se-4p orbitals hybridize at about -6.5 to -5.0 eV, and Mo-4d and Se-4p orbitals hybridize at about -5.0 to -1.0 eV. These hybridizations greatly improve the bonding ability of Mo and Se atom in the interface. By Bader charge analysis, we find electron redistribution near the interface which promotes the bonding of the Mo and MoSe2 layer.

Structure and phase transitions at the interface between α-Al2O3 and Pt

Science.gov (United States)

Ophus, Colin; Santala, Melissa K.; Asta, Mark; Radmilovic, Velimir

2013-06-01

The structure and thermodynamics of interfaces between (111) Pt and the basal plane of α-Al2O3 have been studied through a combination of high-resolution electron microscopy and first-principles calculations. Within the framework of ab initio thermodynamics the structure and excess free energies are calculated as functions of temperature (T) and oxygen partial pressure (PO2), for three competing interface terminations. Comparisons between measurements and calculations establish that the interface is oxygen terminated, and a structural phase transition is predicted in the range of experimentally accessible T and PO2 from the calculated interfacial free energies.

Adaptive contact elements for three-dimensional fluid-structure interfaces

International Nuclear Information System (INIS)

Kulak, R.F.

1985-01-01

A finite element method is developed for treating the mechanics of contact between two deformable bodies which occurs, for example, at fluid-structure interfaces. The method uses a family of adaptive contact elements, which are based upon the penalty method, to handle all of the possible contact configurations that can occur between the discretized contacting bodies. The contact element's nodal connectivity is allowed to change during the computations in order to accommodate finite sliding. The infusion of these elements in the interface results in satisfying the force equilibrium condition during contact. The methodology has been implemented into the NEPTUNE code. Results are presented for an illustrative problem

Adaptive contact elements for three-dimensional fluid-structure interfaces

Energy Technology Data Exchange (ETDEWEB)

Kulak, R.F.

1985-01-01

A finite element method is developed for treating the mechanics of contact between two deformable bodies which occurs, for example, at fluid-structure interfaces. The method uses a family of adaptive contact elements, which are based upon the penalty method, to handle all of the possible contact configurations that can occur between the discretized contacting bodies. The contact element's nodal connectivity is allowed to change during the computations in order to accommodate finite sliding. The infusion of these elements in the interface results in satisfying the force equilibrium condition during contact. The methodology has been implemented into the NEPTUNE code. Results are presented for an illustrative problem.

An Overview of Recent Patents on Musculoskeletal Interface Tissue Engineering

Science.gov (United States)

Rao, Rohit T.; Browe, Daniel P.; Lowe, Christopher J.; Freeman, Joseph W.

2018-01-01

Interface tissue engineering involves the development of engineered grafts that promote integration between multiple tissue types. Musculoskeletal tissue interfaces are critical to the safe and efficient transmission of mechanical forces between multiple musculoskeletal tissues e.g. between ligament and bone tissue. However, these interfaces often do not physiologically regenerate upon injury, resulting in impaired tissue function. Therefore, interface tissue engineering approaches are considered to be particularly relevant for the structural restoration of musculoskeletal tissues interfaces. In this article we provide an overview of the various strategies used for engineering musculoskeletal tissue interfaces with a specific focus on the recent important patents that have been issued for inventions that were specifically designed for engineering musculoskeletal interfaces as well as those that show promise to be adapted for this purpose. PMID:26577344

Smart nanogels at the air/water interface: structural studies by neutron reflectivity

Science.gov (United States)

Zielińska, Katarzyna; Sun, Huihui; Campbell, Richard A.; Zarbakhsh, Ali; Resmini, Marina

2016-02-01

The development of effective transdermal drug delivery systems based on nanosized polymers requires a better understanding of the behaviour of such nanomaterials at interfaces. N-Isopropylacrylamide-based nanogels synthesized with different percentages of N,N'-methylenebisacrylamide as cross-linker, ranging from 10 to 30%, were characterized at physiological temperature at the air/water interface, using neutron reflectivity (NR), with isotopic contrast variation, and surface tension measurements; this allowed us to resolve the adsorbed amount and the volume fraction of nanogels at the interface. A large conformational change for the nanogels results in strong deformations at the interface. As the percentage of cross-linker incorporated in the nanogels becomes higher, more rigid matrices are obtained, although less deformed, and the amount of adsorbed nanogels is increased. The data provide the first experimental evidence of structural changes of nanogels as a function of the degree of cross-linking at the air/water interface.The development of effective transdermal drug delivery systems based on nanosized polymers requires a better understanding of the behaviour of such nanomaterials at interfaces. N-Isopropylacrylamide-based nanogels synthesized with different percentages of N,N'-methylenebisacrylamide as cross-linker, ranging from 10 to 30%, were characterized at physiological temperature at the air/water interface, using neutron reflectivity (NR), with isotopic contrast variation, and surface tension measurements; this allowed us to resolve the adsorbed amount and the volume fraction of nanogels at the interface. A large conformational change for the nanogels results in strong deformations at the interface. As the percentage of cross-linker incorporated in the nanogels becomes higher, more rigid matrices are obtained, although less deformed, and the amount of adsorbed nanogels is increased. The data provide the first experimental evidence of structural changes

Structural basis for IL-1α recognition by a modified DNA aptamer that specifically inhibits IL-1α signaling

Energy Technology Data Exchange (ETDEWEB)

Ren, Xiaoming; Gelinas, Amy D.; von Carlowitz, Ira; Janjic, Nebojsa; Pyle, Anna Marie (Yale); (SomaLogic)

2017-10-09

IL-1α is an essential cytokine that contributes to inflammatory responses and is implicated in various forms of pathogenesis and cancer. Here we report a naphthyl modified DNA aptamer that specifically binds IL-1α and inhibits its signaling pathway. By solving the crystal structure of the IL-1α/aptamer, we provide a high-resolution structure of this critical cytokine and we reveal its functional interaction interface with high-affinity ligands. The non-helical aptamer, which represents a highly compact nucleic acid structure, contains a wealth of new conformational features, including an unknown form of G-quadruplex. The IL-1α/aptamer interface is composed of unusual polar and hydrophobic elements, along with an elaborate hydrogen bonding network that is mediated by sodium ion. IL-1α uses the same interface to interact with both the aptamer and its cognate receptor IL-1RI, thereby suggesting a novel route to immunomodulatory therapeutics.

The structure of the solid-liquid interface: atomic size effect

International Nuclear Information System (INIS)

Geysermans, P.; Pontikis, V.

2002-01-01

The atomic structure of the solid-liquid heterophase interface was investigated by using molecular dynamics. Two kinds of systems were studied; the first one was crystalline copper with (100) and (111) surface terminations in contact with liquid aluminium, while in the second one the interface was modelled by two systems in contact made of Lennard-Jones particles with different size (σ) and energy (ε) parameters. We found that at the interface the liquid was layered whatever the crystallographic orientation of the surface. The layering of the liquid is still preserved when the ratio of particles sites (χ=σ 1 /σ 2 ) changes while an epitaxial relationship is always found between the crystal and the first liquid layer. The average density of the latter is closely related to the χ value. (authors)

Electronic structure at metal-smiconductor surfaces and interfaces: effects of disorder

International Nuclear Information System (INIS)

Rodrigues, D.E.

1988-01-01

The main concern of this work is the study of the electronic structure at metal and semiconductor surfaces or interfaces, with special emphasis in the effects of disorder and local microstructure upon them. Various factors which determine this structure are presented and those of central importance are identified. A model that allows the efficient and exact calculation of the local density of states at disordered interfaces is described. This model is based on a tight-binding hamiltonian that has enough flexibility so as to allow an adequate description of real solids. The disorder is taken into account by including stochastic perturbations in the diagonal elements of the hamiltonian in a site orbital basis. These perturbations are taken at each layer from a lorentzian probability distribution. An exact expression for the calculation of the local density of states is derived and applied to a model surface built up from a type orbitals arranged in a simple cubic lattice. The effects of disorder on the local densities of states and on the existence of surface Tamm states are studied. The properties of the electronic states with this kind of model of disorder are considered. The self-consistent calculation of the electronic structure of the Si(111) - (1x1) surface is presented. The effects of disorder on the electronic properties such as the work function or the position of surface states within the gap are evaluated. The surface of the metallic compound NiSi 2 is also treated. The first self-consistent calculation of the electronic structure of its (111) surface is presented. The electronic structure of the Si/NiSi 2 (111) interfaces is calculated for the two types of junctions that can be grown experimentally. The origin of the difference between the Schottky barrier heights at both interfaces is discussed. The results are compared with available experimental data. The implications of this calculation on existing theories about the microscopic mechanism that causes

Interface Consistency

DEFF Research Database (Denmark)

Staunstrup, Jørgen

1998-01-01

This paper proposes that Interface Consistency is an important issue for the development of modular designs. Byproviding a precise specification of component interfaces it becomes possible to check that separately developedcomponents use a common interface in a coherent matter thus avoiding a very...... significant source of design errors. Awide range of interface specifications are possible, the simplest form is a syntactical check of parameter types.However, today it is possible to do more sophisticated forms involving semantic checks....

Applying data distribution management and ownership management services of the HLA interface specification

NARCIS (Netherlands)

Kuijpers, N.H.L.; Lukkien, J.J.; Brasse, M.H.H.; Huijbrechts, S.

1999-01-01

The HLA Interface Specification defines services for Data Distribution Management (DDM) and Ownership Management (OM). In addition to Declaration Management, DDM is introduced to provide value based filtering on the attribute values to be communicated. The main objectives of DDM are reduction of the

Correlating electronic and geometric structures of organic films and interfaces by means of synchrotron radiation based techniques

International Nuclear Information System (INIS)

Yamane, Hiroyuki

2013-01-01

The electronic structure of organic thin films and interfaces plays a crucial role in the performance of optoelectronic devices using organic semiconductors, and is seriously dominated by the geometric film/interface structure due to the anisotropic spatial distribution of molecular orbitals. This paper briefly reviews the recent progress of the examination of correlating electronic structure and geometric structure of archetypal organic semiconductor thin films and interfaces by using spectroscopic experiments with synchrotron radiation such as angle-resolved photoelectron spectroscopy, x-ray absorption spectroscopy, and x-ray standing wave. (author)

The structural basis of Arf effector specificity: the crystal structure of ARF6 in a complex with JIP4.

Science.gov (United States)

Isabet, Tatiana; Montagnac, Guillaume; Regazzoni, Karine; Raynal, Bertrand; El Khadali, Fatima; England, Patrick; Franco, Michel; Chavrier, Philippe; Houdusse, Anne; Ménétrey, Julie

2009-09-16

The JNK-interacting proteins, JIP3 and JIP4, are specific effectors of the small GTP-binding protein ARF6. The interaction of ARF6-GTP with the second leucine zipper (LZII) domains of JIP3/JIP4 regulates the binding of JIPs to kinesin-1 and dynactin. Here, we report the crystal structure of ARF6-GTP bound to the JIP4-LZII at 1.9 A resolution. The complex is a heterotetramer with dyad symmetry arranged in an ARF6-(JIP4)(2)-ARF6 configuration. Comparison of the ARF6-JIP4 interface with the equivalent region of ARF1 shows the structural basis of JIP4's specificity for ARF6. Using site-directed mutagenesis and surface plasmon resonance, we further show that non-conserved residues at the switch region borders are the key structural determinants of JIP4 specificity. A structure-derived model of the association of the ARF6-JIP3/JIP4 complex with membranes shows that the JIP4-LZII coiled-coil should lie along the membrane to prevent steric hindrances, resulting in only one ARF6 molecule bound. Such a heterotrimeric complex gives insights to better understand the ARF6-mediated motor switch regulatory function.

Preventing tissue fibrosis by local biomaterials interfacing of specific cryptic extracellular matrix information

Science.gov (United States)

Horejs, Christine-Maria; St-Pierre, Jean-Philippe; Ojala, Juha R. M.; Steele, Joseph A. M.; da Silva, Patricia Barros; Rynne-Vidal, Angela; Maynard, Stephanie A.; Hansel, Catherine S.; Rodríguez-Fernández, Clara; Mazo, Manuel M.; You, Amanda Y. F.; Wang, Alex J.; von Erlach, Thomas; Tryggvason, Karl; López-Cabrera, Manuel; Stevens, Molly M.

2017-01-01

Matrix metalloproteinases (MMPs) contribute to the breakdown of tissue structures such as the basement membrane, promoting tissue fibrosis. Here we developed an electrospun membrane biofunctionalized with a fragment of the laminin β1-chain to modulate the expression of MMP2 in this context. We demonstrate that interfacing of the β1-fragment with the mesothelium of the peritoneal membrane via a biomaterial abrogates the release of active MMP2 in response to transforming growth factor β1 and rescues tissue integrity ex vivo and in vivo in a mouse model of peritoneal fibrosis. Importantly, our data demonstrate that the membrane inhibits MMP2 expression. Changes in the expression of epithelial-to-mesenchymal transition (EMT)-related molecules further point towards a contribution of the modulation of EMT. Biomaterial-based presentation of regulatory basement membrane signals directly addresses limitations of current therapeutic approaches by enabling a localized and specific method to counteract MMP2 release applicable to a broad range of therapeutic targets. PMID:28593951

Preventing tissue fibrosis by local biomaterials interfacing of specific cryptic extracellular matrix information

Science.gov (United States)

Horejs, Christine-Maria; St-Pierre, Jean-Philippe; Ojala, Juha R. M.; Steele, Joseph A. M.; da Silva, Patricia Barros; Rynne-Vidal, Angela; Maynard, Stephanie A.; Hansel, Catherine S.; Rodríguez-Fernández, Clara; Mazo, Manuel M.; You, Amanda Y. F.; Wang, Alex J.; von Erlach, Thomas; Tryggvason, Karl; López-Cabrera, Manuel; Stevens, Molly M.

2017-06-01

Matrix metalloproteinases (MMPs) contribute to the breakdown of tissue structures such as the basement membrane, promoting tissue fibrosis. Here we developed an electrospun membrane biofunctionalized with a fragment of the laminin β1-chain to modulate the expression of MMP2 in this context. We demonstrate that interfacing of the β1-fragment with the mesothelium of the peritoneal membrane via a biomaterial abrogates the release of active MMP2 in response to transforming growth factor β1 and rescues tissue integrity ex vivo and in vivo in a mouse model of peritoneal fibrosis. Importantly, our data demonstrate that the membrane inhibits MMP2 expression. Changes in the expression of epithelial-to-mesenchymal transition (EMT)-related molecules further point towards a contribution of the modulation of EMT. Biomaterial-based presentation of regulatory basement membrane signals directly addresses limitations of current therapeutic approaches by enabling a localized and specific method to counteract MMP2 release applicable to a broad range of therapeutic targets.

HomPPI: a class of sequence homology based protein-protein interface prediction methods

Directory of Open Access Journals (Sweden)

Dobbs Drena

2011-06-01

Full Text Available Abstract Background Although homology-based methods are among the most widely used methods for predicting the structure and function of proteins, the question as to whether interface sequence conservation can be effectively exploited in predicting protein-protein interfaces has been a subject of debate. Results We studied more than 300,000 pair-wise alignments of protein sequences from structurally characterized protein complexes, including both obligate and transient complexes. We identified sequence similarity criteria required for accurate homology-based inference of interface residues in a query protein sequence. Based on these analyses, we developed HomPPI, a class of sequence homology-based methods for predicting protein-protein interface residues. We present two variants of HomPPI: (i NPS-HomPPI (Non partner-specific HomPPI, which can be used to predict interface residues of a query protein in the absence of knowledge of the interaction partner; and (ii PS-HomPPI (Partner-specific HomPPI, which can be used to predict the interface residues of a query protein with a specific target protein. Our experiments on a benchmark dataset of obligate homodimeric complexes show that NPS-HomPPI can reliably predict protein-protein interface residues in a given protein, with an average correlation coefficient (CC of 0.76, sensitivity of 0.83, and specificity of 0.78, when sequence homologs of the query protein can be reliably identified. NPS-HomPPI also reliably predicts the interface residues of intrinsically disordered proteins. Our experiments suggest that NPS-HomPPI is competitive with several state-of-the-art interface prediction servers including those that exploit the structure of the query proteins. The partner-specific classifier, PS-HomPPI can, on a large dataset of transient complexes, predict the interface residues of a query protein with a specific target, with a CC of 0.65, sensitivity of 0.69, and specificity of 0.70, when homologs of

Prediction of protein–protein interactions: unifying evolution and structure at protein interfaces

International Nuclear Information System (INIS)

Tuncbag, Nurcan; Gursoy, Attila; Keskin, Ozlem

2011-01-01

The vast majority of the chores in the living cell involve protein–protein interactions. Providing details of protein interactions at the residue level and incorporating them into protein interaction networks are crucial toward the elucidation of a dynamic picture of cells. Despite the rapid increase in the number of structurally known protein complexes, we are still far away from a complete network. Given experimental limitations, computational modeling of protein interactions is a prerequisite to proceed on the way to complete structural networks. In this work, we focus on the question 'how do proteins interact?' rather than 'which proteins interact?' and we review structure-based protein–protein interaction prediction approaches. As a sample approach for modeling protein interactions, PRISM is detailed which combines structural similarity and evolutionary conservation in protein interfaces to infer structures of complexes in the protein interaction network. This will ultimately help us to understand the role of protein interfaces in predicting bound conformations

Mesoscopic multiphase structures and the interfaces of block and graft copolymers in bulk

International Nuclear Information System (INIS)

Matsushita, Yushu

1996-01-01

Microphase-separated structures of copolymers with various architectures and their polymer/polymer interfaces were studied. They are SP diblock, PSP triblock, and SPP graft copolymers, where S and P denote polystyrene and poly(2-vinylpyridine), respectively. Morphological observations were carried out by means of transmission electron microscopy and small-angle X-ray scattering. Chain dimensions of component polymers were measured by small-angle neutron scattering and microphase-separated interfaces were observed by neutron reflectivity measurements using deuterium-labeled samples. It was clarified that morphological phase transitions among thermodynamically equilibrium structures for SP diblock and PSP triblock copolymers occur at almost the same compositions; however, those of SPP graft copolymers tend to occur at higher volume fraction of polystyrene, φ s , than those for block copolymers. As for alternating lamellar structures it turned out to be clear that lamellar domain spacings, D's, were scaled as the 2/3 power of the molecular weight of polymers irrespective of their architectures. S block chains of SP diblock and PSP triblock copolymers in lamellar structures were both confirmed to be deformed toward the direction perpendicular to the lamellar interfaces, but it revealed that their volumes were preserved. Further, S/P interfacial thicknesses of SP and PSP were essentially the same to each other and the values defined as the FWHM of the error functions which express the segment density distributions of the interfaces were determined to be about 4 nm. (author)

Atomic-scale structures of interfaces between phyllosilicate edges and water

NARCIS (Netherlands)

Liu, X.; Lu, X.; Meijer, E.J.; Wang, R.; Zhou, H.

2012-01-01

We report first-principles molecular dynamics (FPMD) studies on the structures of interfaces between phyllosilicate edges and water. Using FPMD, the substrates and solvents are simulated at the same first-principles level, and the thermal motions are sampled via molecular dynamics. Both the neutral

Structural and electronic properties of the transition layer at the SiO2/4H-SiC interface

Directory of Open Access Journals (Sweden)

Wenbo Li

2015-01-01

Full Text Available Using first-principles methods, we generate an amorphous SiO2/4H-SiC interface with a transition layer. Based this interface model, we investigate the structural and electronic properties of the interfacial transition layer. The calculated Si 2p core-level shifts for this interface are comparable to the experimental data, indicating that various SiCxOy species should be present in this interface transition layer. The analysis of the electronic structures reveals that the tetrahedral SiCxOy structures cannot introduce any of the defect states at the interface. Interestingly, our transition layer also includes a C-C=C trimer and SiO5 configurations, which lead to the generation of interface states. The accurate positions of Kohn-Sham energy levels associated with these defects are further calculated within the hybrid functional scheme. The Kohn-Sham energy levels of the carbon trimer and SiO5 configurations are located near the conduction and valence band of bulk 4H-SiC, respectively. The result indicates that the carbon trimer occurred in the transition layer may be a possible origin of near interface traps. These findings provide novel insight into the structural and electronic properties of the realistic SiO2/SiC interface.

TEM characterization of invariant line interfaces and structural ledges in a Mo-Si alloy

International Nuclear Information System (INIS)

Xiao, S.Q.; Dahmen, U.; Maloy, S.A.; Heuer, A.H.

1995-06-01

Two distinct lath morphologies of Mo 5 Si 3 precipitates observed in MoSi 2 differ in their cross-sectional shape and lattice orientation. Type I laths exhibit a rectangular cross section, with interfaces parallel to low-index planes, while Type II laths are parallelogram-shaped, with their major interface at 13 degree to the Type I precipitate. The corresponding orientation relationships differ by a 1.8 degree rotation around the lath axis. In this study, the difference between the two characteristic morphologies and orientation relationships is shown to be the formation of an invariant line strain for Type II precipitates. On an atomic scale, both interfaces have a terrace and ledge structure but differ in the stacking sequence of interfacial ledges associated with partial dislocations. The structural unit model and the invariant line model predict identical interface geometries which agree closely with the observations

Interface engineering in inorganic hybrid structures towards improved photocatalysis (Conference Presentation)

Science.gov (United States)

Xiong, Yujie

2016-10-01

Designing new photocatalytic materials for improving photoconversion efficiency is a promising route to alleviate the steadily worsening environmental issues and energy crisis. Despite the invention of a large number of catalytic materials with well-defined structures, their overall efficiency in photocatalysis is still quite limited as the three key steps - light harvesting, charge generation and separation, and charge transfer to surface for redox reactions - have not been substantially improved. To improve each step in the complex process, there is a major trend to develop materials based on inorganic hybrid structures. In this case, interface engineering holds the promise for boosting the overall efficiency, given the key roles of interface structures in charge and energy transfer. In this talk, I will demonstrate several different approaches to designing inorganic hybrid structures with improved photocatalytic performance via interface engineering. The typical demonstrations include semiconductor-plasmonics systems for broad-spectrum light harvesting, metal-semiconductor interfaces for improved charge separation, semiconductor-MOF (metal-organic framework) configurations for activated surface reactions. It is anticipated that this series of works open a new window to rationally designing inorganic hybrid materials for photo-induced applications. References: (1) Bai, S.; Yang, L.; Wang, C.; Lin, Y.; Lu, J.; Jiang, J. and Xiong, Y.*, Angew. Chem. Int. Ed. 54, 14810-14814 (2015). (2) Bai, S.; Jiang, J.; Zhang, Q. and Xiong, Y.*, Chem. Soc. Rev. 44, 2893-2939 (2015). (3) Bai, S.; Li, X.; Kong, Q.; Long, R.; Wang, C.; Jiang, J. and Xiong, Y.*, Adv. Mater. 27, 3444-3452 (2015). (4) Bai, S.; Ge, J.; Wang, L.; Gong, M.; Deng, M.; Kong, Q.; Song, L.; Jiang, J.;* Zhang, Q.;* Luo, Y.; Xie, Y. and Xiong, Y.*, Adv. Mater. 26, 5689-5695 (2014). (5) Li, R.; Hu, J.; Deng, M.; Wang, H.; Wang, X.; Hu, Y.; Jiang, H. L.; Jiang, J.;* Zhang, Q.;* Xie, Y. and Xiong, Y.*, Adv. Mater

Cathodoluminescence study of Si/SiO2 interface structure

International Nuclear Information System (INIS)

Zamoryarskaya, M.V.; Sokolov, V.I.; Plotnikov, V.

2004-01-01

The structure of interface of thermal silicon oxide on p- and n-silicon with different content of activators (boron and phosphorus) was studied by using the method of the local cathodoluminescence (CL). The results of the CL study of the thick silicon oxide layers on silicon show that the content of the defects related with oxygen deficit decreases near the interface. In the same time, new bands in green and red range appear in CL spectra. The CL spectra of the layer with thickness 5-15 nm near interface are analogous to CL spectra of a composite of silicon nanoclusters and silicon oxide. The comparison of CL spectra of silicon oxide grown on p- and n-silicon shows that the film on p-silicon is characterized by higher concentration of silicon-deficit defects and silicon 'islands' near the surface. It may be the cause why the electrical hardness of silicon oxide on p-silicon is lower than the one on n-silicon. The integral electro-physical characteristics of silicon oxide also were measured. The bulk charge and the density of interface states of silicon oxide on p-silicon are higher than for oxide on n-silicon. The oxidization of n-silicon with nanostructure surface leads to the appearance of the CL bands related with oxygen deficit and silicon 'islands' in silicon oxide

Interface properties of bilayer structure Alq{sub 3}/Fe{sub 65}Co{sub 35}

Energy Technology Data Exchange (ETDEWEB)

Wang, Zhen, E-mail: wangzhen@chd.edu.cn [Department of Applied Physics, Chang’an University, Xi’an 710064 (China); Xu, Chunlong; Wang, Jinguo; Chang, Qiaoli [Department of Applied Physics, Chang’an University, Xi’an 710064 (China); Zuo, Yalu; Xi, Li [Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou 730000 (China)

2015-04-01

Highlights: • Bilayer structure of Alq{sub 3}/FeCo was fabricated in a dual ultra high vacuum chamber. • Organic layer reacts partially with the FeCo film. • Electronic injection barrier is 0.76 eV in the interface. • The induced uniaxial anisotropy appears in Alq{sub 3}/FeCo. - Abstract: The interface between the organic and magnetic electrodes is a fundamental problem in organic spintronics devices. Therefore, bilayer structure of Alq{sub 3}/FeCo was fabricated in a dual ultra high vacuum chamber. The electronic structure of Alq{sub 3}–FeCo interface has been studied by X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy with Argon ion etching technique. It was found that organic layer reacts partially with the FeCo film, forming complex binding of metallic carbide and/or oxidation state in the interfacial region. Electronic injection barrier is 0.76 eV in the interface. The structural variation of the contact region is proposed to be one of the possible factors resulting in spin-injection failure. The magnetic properties of FeCo film with different thicknesses on glass substrate and Alq{sub 3} layer are also investigated. The induced uniaxial anisotropy only presents in 3 nm FeCo thickness for glass/FeCo, while it appears in 3–5 nm FeCo for Alq{sub 3}/FeCo.

Lateral strength force of URM structures based on a constitutive model for interface element

Directory of Open Access Journals (Sweden)

A.H. Akhaveissy

Full Text Available This paper presents the numerical implementation of a new proposed interface model for modeling the behavior of mortar joints in masonry walls. Its theoretical framework is fully based on the plasticity theory. The Von Mises criterion is used to simulate the behavior of brick and stone units. The interface laws for contact elements are formulated to simulate the softening behavior of mortar joints under tensile stress; a normal linear cap model is also used to limit compressive stress. The numerical predictions based on the proposed model for the behavior of interface elements correlate very highly with test data. A new explicit formula based on results of proposed interface model is also presented to estimate the strength of unreinforced masonry structures. The closed form solution predicts the ultimate lateral load of unreinforced masonry walls less error percentage than ATC and FEMA-307. Consequently, the proposed closed form solution can be used satisfactorily to analyze unreinforced masonry structures.

Role of interface states on electron transport in a-Si:H/nc-Si:H multilayer structures

Science.gov (United States)

Yadav, Asha; Kumari, Juhi; Agarwal, Pratima

2018-05-01

In this paper we report, I-V characteristic of a-Si:H/nc-Si:H multilayer structures in lateral as well as transverse direction. In lateral geometry, where the interfaces are parallel to the direction of electronic transport, residual photo conductivity (persistent photoconductivity) is observed after the light was turned off. On the other hand, in transverse geometry, where interfaces are along the direction of electronic transport, the space charge limited currents are affected and higher density of states is obtained. The PPC was more in the structures where numbers of such interface were more. These results have been understood in terms of the charge carriers trapped at the interface, which influence the electronic transport.

Interactive displays natural human-interface technologies

CERN Document Server

Bhowmik, Achintya K

2014-01-01

One of the first books to provide an in-depth discussion of the technologies, applications and trends in the rapidly emerging field of interactive displays (touch, gesture & voice) The book will cover the technologies, applications and trends in the field of interactive displays, namely interfaces based on touch, gesture and voice and those using a combination of these technologies. The book will be split into 4 main parts with each being dedicated to a specific user interface. Part 1 ''Touch Interfaces'' will provide a review of the currently deployed touch-screen technologies and applications. It will also cover the recent developments towards achieving thinner, lightweight and cost-reduced touch screen panels in the future via integration of touch functionalities. Part 2 ''Gesture Interfaces'' will examine techniques and applications in stereoscopic 3D computer vision, structured-light 3D computer vision and time-of-flight 3D computer vision in gesture interfaces. Part 3 ''Voice Interfaces'' will revie...

High Performance Computing - Power Application Programming Interface Specification.

Energy Technology Data Exchange (ETDEWEB)

Laros, James H.,; Kelly, Suzanne M.; Pedretti, Kevin; Grant, Ryan; Olivier, Stephen Lecler; Levenhagen, Michael J.; DeBonis, David

2014-08-01

Measuring and controlling the power and energy consumption of high performance computing systems by various components in the software stack is an active research area [13, 3, 5, 10, 4, 21, 19, 16, 7, 17, 20, 18, 11, 1, 6, 14, 12]. Implementations in lower level software layers are beginning to emerge in some production systems, which is very welcome. To be most effective, a portable interface to measurement and control features would significantly facilitate participation by all levels of the software stack. We present a proposal for a standard power Application Programming Interface (API) that endeavors to cover the entire software space, from generic hardware interfaces to the input from the computer facility manager.

Solid-melt interface structure and growth of Cu alloy single crystals

International Nuclear Information System (INIS)

Tomimitsu, Hiroshi; Kamada, Kohji.

1983-01-01

Crystal-melt interface behavior during the growth of Cu-base solid solutions by the Bridgman method is discussed on the basis of experimental evidence obtained by neutron diffraction topography. Advantages of neutron diffraction topography for the characterization of large single crystals, such as dealt with in this paper, are emphasized. Evidence was odserved of extremely regular crystal growth along directions, irrespective of the macroscopic growth direction. This contrasts with the previously believed (110) normal growth which is a conclusion of growth theory based on molecular kinetics at the solid-melt interface. In consequence, we believe that the kinetics at the interface is a minor factor in the meltgrowth of metal single crystals. Revised melt-growth theory should include both the growth and the formation of the regular structure as evidenced by neutron diffraction topography. (author)

Aqueous turbulence structure immediately adjacent to the air - water interface and interfacial gas exchange

Science.gov (United States)

Wang, Binbin

Air-sea interaction and the interfacial exchange of gas across the air-water interface are of great importance in coupled atmospheric-oceanic environmental systems. Aqueous turbulence structure immediately adjacent to the air-water interface is the combined result of wind, surface waves, currents and other environmental forces and plays a key role in energy budgets, gas fluxes and hence the global climate system. However, the quantification of turbulence structure sufficiently close to the air-water interface is extremely difficult. The physical relationship between interfacial gas exchange and near surface turbulence remains insufficiently investigated. This dissertation aims to measure turbulence in situ in a complex environmental forcing system on Lake Michigan and to reveal the relationship between turbulent statistics and the CO2 flux across the air-water interface. The major objective of this dissertation is to investigate the physical control of the interfacial gas exchange and to provide a universal parameterization of gas transfer velocity from environmental factors, as well as to propose a mechanistic model for the global CO2 flux that can be applied in three dimensional climate-ocean models. Firstly, this dissertation presents an advanced measurement instrument, an in situ free floating Particle Image Velocimetry (FPIV) system, designed and developed to investigate the small scale turbulence structure immediately below the air-water interface. Description of hardware components, design of the system, measurement theory, data analysis procedure and estimation of measurement error were provided. Secondly, with the FPIV system, statistics of small scale turbulence immediately below the air-water interface were investigated under a variety of environmental conditions. One dimensional wave-number spectrum and structure function sufficiently close to the water surface were examined. The vertical profiles of turbulent dissipation rate were intensively studied

Electronic structure of disordered alloys, surfaces and interfaces

CERN Document Server

Turek, Ilja; Kudrnovský, Josef; Šob, Mojmír; Weinberger, Peter

1997-01-01

At present, there is an increasing interest in the prediction of properties of classical and new materials such as substitutional alloys, their surfaces, and metallic or semiconductor multilayers. A detailed understanding based on a thus of the utmost importance for fu­ microscopic, parameter-free approach is ture developments in solid state physics and materials science. The interrela­ tion between electronic and structural properties at surfaces plays a key role for a microscopic understanding of phenomena as diverse as catalysis, corrosion, chemisorption and crystal growth. Remarkable progress has been made in the past 10-15 years in the understand­ ing of behavior of ideal crystals and their surfaces by relating their properties to the underlying electronic structure as determined from the first principles. Similar studies of complex systems like imperfect surfaces, interfaces, and mul­ tilayered structures seem to be accessible by now. Conventional band-structure methods, however, are of limited use ...

A first principles study of adhesion and electronic structure at Fe (110)/graphite (0001) interface

Energy Technology Data Exchange (ETDEWEB)

Liu, Yangzhen; Xing, Jiandong; Li, Yefei, E-mail: yefeili@126.com; Sun, Liang; Wang, Yong

2017-05-31

Highlights: • The surface energy of graphite (0001) and Fe (110) has been calculated and the number of layers of graphite slab and Fe slab has been estimated. • The work of adhesion of Fe (110)/graphite (0001) interface with different interfacial separation d{sub 0} (1.7–3 Å) has been systematically discussed. • The total electron density and electron density difference of Fe (110)/graphite (0001) are used to study the bonding characteristics. • The Interfacial energy and fracture toughness of Fe (110)/graphite (0001) are estimated. - Abstract: Using first–principles calculations, we discuss the bulk properties of bcc Fe and graphite and that of the surface, the work of adhesion, and the electronic structure of Fe (110)/graphite (0001) interface. In this study, the experimental results of the bulk properties of bcc Fe and graphite reveal that our adopted parameters are reliable. Moreover, the results of surface energy demonstrate that nine atomic layers of graphite (0001) and five atomic layers of Fe (110) exhibit bulk–like interiors. The lattice mismatch of Fe (110)/graphite (0001) interface is about 6%. The results also exhibit that the Fe atom residing on top of the second layer of graphite slab (HCP structure) is the preferred stacking sequence. The work of adhesion (W{sub ad}) of the optimized Fe/graphite interface of HCP structure is 1.36 J/m{sup 2}. Electronic structures indicate that the bonding characteristics are a mixture of covalent and ionic bonds in the HCP interface. Moreover, the magnetic moment of atoms at the interface was studied using the spin polarized density of states.

Better Educational Website Interface Design: The Implications from Gender-Specific Preferences in Graduate Students

Science.gov (United States)

Hsu, Yu-chang

2006-01-01

This study investigated graduate students gender-specific preferences for certain website interface design features, intending to generate useful information for instructors in choosing and for website designers in creating educational websites. The features investigated in this study included colour value, major navigation buttons placement, and…

Interfaces of nuclear structure studies-decay vs. in-beam experiments

International Nuclear Information System (INIS)

Grawe, H.; Gorska, M.; Hu, Z.; Roeckl, E.; Lipoglavsek, M.; Fahlander, C.; Rykaczewski, K.

1999-05-01

The common interface of β-decay and particle-decay experiments and in-beam studies following fusion, relativistic fission and projectile fragmentation is defined by the search for the best way to extract nuclear structure information. For a few examples selected from the exotic regions of nuclei around 100 Sn and between 68 Ni and 78 Ni it is demonstrated, that complementary spectroscopic data extracted by various methods lead to an understanding of the shell structure at these keypoints of the nuclidic chart. (orig.)

Finding optimal interaction interface alignments between biological complexes

KAUST Repository

Cui, Xuefeng

2015-06-13

Motivation: Biological molecules perform their functions through interactions with other molecules. Structure alignment of interaction interfaces between biological complexes is an indispensable step in detecting their structural similarities, which are keys to understanding their evolutionary histories and functions. Although various structure alignment methods have been developed to successfully access the similarities of protein structures or certain types of interaction interfaces, existing alignment tools cannot directly align arbitrary types of interfaces formed by protein, DNA or RNA molecules. Specifically, they require a \\'blackbox preprocessing\\' to standardize interface types and chain identifiers. Yet their performance is limited and sometimes unsatisfactory. Results: Here we introduce a novel method, PROSTA-inter, that automatically determines and aligns interaction interfaces between two arbitrary types of complex structures. Our method uses sequentially remote fragments to search for the optimal superimposition. The optimal residue matching problem is then formulated as a maximum weighted bipartite matching problem to detect the optimal sequence order-independent alignment. Benchmark evaluation on all non-redundant protein-DNA complexes in PDB shows significant performance improvement of our method over TM-align and iAlign (with the \\'blackbox preprocessing\\'). Two case studies where our method discovers, for the first time, structural similarities between two pairs of functionally related protein-DNA complexes are presented. We further demonstrate the power of our method on detecting structural similarities between a protein-protein complex and a protein-RNA complex, which is biologically known as a protein-RNA mimicry case. © The Author 2015. Published by Oxford University Press.

Friction, slip and structural inhomogeneity of the buried interface

International Nuclear Information System (INIS)

Dong, Y; Wu, J; Martini, A; Li, Q

2011-01-01

An atomistic model of metallic contacts using realistic interatomic potentials is used to study the connection between friction, slip and the structure of the buried interface. Incommensurability induced by misalignment and lattice mismatch is modeled with contact sizes that are large enough to observe superstructures formed by the relative orientations of the surfaces. The periodicity of the superstructures is quantitatively related to inhomogeneous shear stress distributions in the contact area, and a reduced order model is used to clarify the connection between friction and structural inhomogeneity. Finally, the movement of atoms is evaluated before, during and after slip in both aligned and misaligned contacts to understand how the interfacial structure affects the mechanisms of slip and the corresponding frictional behavior

Interface Structure and Elements Diffusion of As-Cast and Annealed Ductile Iron/Stainless Steel Bimetal Castings

Directory of Open Access Journals (Sweden)

M. Ramadan

2018-04-01

Full Text Available Bimetal casting is considered to a promising technique for the production of high performance function materials. Heat treatment process for bimetal castings became an essential tool for improving interface structure and metallurgical diffusion bond. Molten iron alloy with carbon equivalent of 4.40 is poured into sand mold cavities containing solid 304 stainless steel strips insert. Specimens are heated to 7200C in an electrical heating furnace and holded at 720 0C for 60min and 180min. For as-cast specimens, a good coherent interface structure of ductile cast iron/304 stainless bimetal with four layers interfacial microstructure are obtained. Low temperature annealing at 720oC has a significat effect on the interface layers structure, where, three layers of interface structure are obtained after 180min annealing time because of the complete dissolving of thin layer of ferrite and multi carbides (Layer 2. Low temperature annealing shows a significant effect on the diffusion of C and otherwise shows slightly effect on the diffusion of Cr and Ni. Plearlite phase of Layer 3 is trsformed to spheroidal shape instead of lamallar shape in as-cast bimetals by low tempeature annealing at 720oC. The percent of the performed spheroidal cementit increases by increasing anneaaling time. Hardness of interface layers is changed by low temperauture annealing due to the significant carbon deffussion.

Observation of carbon growth and interface structures in methanol solution

Science.gov (United States)

Okuno, Kimio

2015-11-01

In the deposition of carbon on the surface of a tungsten tip in methanol solution by electrolysis, the growth structure of the carbon films, the interface state, and the dissolution of carbon atoms into the tungsten matrix of the substrate have been investigated with the atomic events by field ion microscopy (FIM). The carbon films preferentially condense on the W{111} plane. The interfacial reaction at the carbon atom-tungsten substrate interface is vigorous and the carbon atoms also readily dissolve into the substrate matrix to form a tungsten-carbon complex. The reaction depth of the deposited carbon depends on the magnitude of electrolytic current and the treatment duration in the methanol solution. In this work, the resolution depth of carbon was found to be approximately 270 atomic layers below the top layer of the tungsten substrate by a field evaporation technique. In the case of a low electrolytic current, the tungsten substrate surface is entirely covered with carbon atoms having a pseudomorphic structure. The field-electron emission characteristics were also evaluated for various coverages of the carbon film formed on the substrate.

Conforming to interface structured adaptive mesh refinement: 3D algorithm and implementation

Science.gov (United States)

Nagarajan, Anand; Soghrati, Soheil

2018-03-01

A new non-iterative mesh generation algorithm named conforming to interface structured adaptive mesh refinement (CISAMR) is introduced for creating 3D finite element models of problems with complex geometries. CISAMR transforms a structured mesh composed of tetrahedral elements into a conforming mesh with low element aspect ratios. The construction of the mesh begins with the structured adaptive mesh refinement of elements in the vicinity of material interfaces. An r-adaptivity algorithm is then employed to relocate selected nodes of nonconforming elements, followed by face-swapping a small fraction of them to eliminate tetrahedrons with high aspect ratios. The final conforming mesh is constructed by sub-tetrahedralizing remaining nonconforming elements, as well as tetrahedrons with hanging nodes. In addition to studying the convergence and analyzing element-wise errors in meshes generated using CISAMR, several example problems are presented to show the ability of this method for modeling 3D problems with intricate morphologies.

Atomic and electronic structures of lattice mismatched Cu{sub 2}O/TiO{sub 2} interfaces

Energy Technology Data Exchange (ETDEWEB)

Wang, Shuzhi [Materials Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Mail Stop 66, Berkeley, California 94720 (United States); Kavaipatti, Balasubramaniam; Ramesh, Ramamoorthy [Department of Materials Science and Engineering, University of California at Berkeley, Berkeley, California 94720 (United States); Kim, Sung-Joo; Pan, Xiaoqing [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Ager, Joel W.; Wang, Lin-Wang, E-mail: lwwang@lbl.gov [Materials Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Mail Stop 66, Berkeley, California 94720 (United States); Joint Center of Artificial Photosynthesis, Berkeley, California 94720 (United States)

2014-05-26

Heterojunction interfaces between metal oxides are often highly lattice mismatched. The atomic and electronic structures of such interfaces, however, are not well understood. We have synthesized Cu{sub 2}O/TiO{sub 2} heterojunction thin films with 13% lattice mismatch and studied the interface via experimental methods and large-scale density function theory calculations of supercells containing ∼1300 atoms. We find that an interface of epitaxial quality is formed via a coincidence site lattice of 8 Cu{sub 2}O unit cells matching 9 TiO{sub 2} unit cells. Calculations reveal the existence of a dislocation core of the O sublattices at the interface and a random arrangement of one layer of interfacial Cu atoms. The interfacial electronic structure is found to be mostly determined by the interfacial Cu distribution, rather than by the O dislocation core. The conduction band minimum and valence band maximum states are spatially separated, and there is no strongly localized state near the core.

Feasibility of task-specific brain-machine interface training for upper-extremity paralysis in patients with chronic hemiparetic stroke.

Science.gov (United States)

Nishimoto, Atsuko; Kawakami, Michiyuki; Fujiwara, Toshiyuki; Hiramoto, Miho; Honaga, Kaoru; Abe, Kaoru; Mizuno, Katsuhiro; Ushiba, Junichi; Liu, Meigen

2018-01-10

Brain-machine interface training was developed for upper-extremity rehabilitation for patients with severe hemiparesis. Its clinical application, however, has been limited because of its lack of feasibility in real-world rehabilitation settings. We developed a new compact task-specific brain-machine interface system that enables task-specific training, including reach-and-grasp tasks, and studied its clinical feasibility and effectiveness for upper-extremity motor paralysis in patients with stroke. Prospective beforeâ€"after study. Twenty-six patients with severe chronic hemiparetic stroke. Participants were trained with the brain-machine interface system to pick up and release pegs during 40-min sessions and 40 min of standard occupational therapy per day for 10 days. Fugl-Meyer upper-extremity motor (FMA) and Motor Activity Log-14 amount of use (MAL-AOU) scores were assessed before and after the intervention. To test its feasibility, 4 occupational therapists who operated the system for the first time assessed it with the Quebec User Evaluation of Satisfaction with assistive Technology (QUEST) 2.0. FMA and MAL-AOU scores improved significantly after brain-machine interface training, with the effect sizes being medium and large, respectively (pmachine interface system is feasible for use in real-world clinical settings.

Electronic structure and electron dynamics at an organic molecule/metal interface: interface states of tetra-tert-butyl-imine/Au(111)

International Nuclear Information System (INIS)

Hagen, Sebastian; Wolf, Martin; Tegeder, Petra; Luo Ying; Haag, Rainer

2010-01-01

Time- and angle-resolved two-photon photoemission (2PPE) spectroscopies have been used to investigated the electronic structure, electron dynamics and localization at the interface between tetra-tert-butyl imine (TBI) and Au(111). At a TBI coverage of one monolayer (ML), the two highest occupied molecular orbitals, HOMO and HOMO-1, are observed at an energy of -1.9 and -2.6 eV below the Fermi level (E F ), respectively, and coincide with the d-band features of the Au substrate. In the unoccupied electronic structure, the lowest unoccupied molecular orbital (LUMO) has been observed at 1.6 eV with respect to E F . In addition, two delocalized states that arise from the modified image potential at the TBI/metal interface have been identified. Their binding energies depend strongly on the adsorption structure of the TBI adlayer, which is coverage dependent in the submonolayer (≤1 ML) regime. Thus the binding energy of the lower interface state (IS) shifts from 3.5 eV at 1.0 ML to 4.0 eV at 0.5 ML, which is accompanied by a pronounced decrease in its lifetime from 100 fs to below 10 fs. This is a result of differences in the wave function overlap with electronic states of the Au(111) substrate at different binding energies. This study shows that in order to fully understand the electronic structure of organic adsorbates at metal surfaces, not only adsorbate- and substrate-induced electronic states have to be considered but also ISs, which are the result of a potential formed by the interaction between the adsorbate and the substrate.

Engineering the Surface/Interface Structures of Titanium Dioxide Micro and Nano Architectures towards Environmental and Electrochemical Applications

Directory of Open Access Journals (Sweden)

Xiaoliang Wang

2017-11-01

Full Text Available Titanium dioxide (TiO2 materials have been intensively studied in the past years because of many varied applications. This mini review article focuses on TiO2 micro and nano architectures with the prevalent crystal structures (anatase, rutile, brookite, and TiO2(B, and summarizes the major advances in the surface and interface engineering and applications in environmental and electrochemical applications. We analyze the advantages of surface/interface engineered TiO2 micro and nano structures, and present the principles and growth mechanisms of TiO2 nanostructures via different strategies, with an emphasis on rational control of the surface and interface structures. We further discuss the applications of TiO2 micro and nano architectures in photocatalysis, lithium/sodium ion batteries, and Li–S batteries. Throughout the discussion, the relationship between the device performance and the surface/interface structures of TiO2 micro and nano structures will be highlighted. Then, we discuss the phase transitions of TiO2 nanostructures and possible strategies of improving the phase stability. The review concludes with a perspective on the current challenges and future research directions.

Structure and Properties of the Fe/Y2O3 Interface from First Principles Calculations

Energy Technology Data Exchange (ETDEWEB)

Choudhury, Samrat [Los Alamos National Laboratory; Stanek, Christopher R. [Los Alamos National Laboratory; Uberuaga, Blas P. [Los Alamos National Laboratory

2012-07-31

Fundamentals of radiation damage are: (1) Formation of Frenkel pair (interstitial-vacancy pair) defects in the lattice; (2) Concentration of Frenkel pair defects >>> thermal equilibrium thermodynamic concentration; and (3) The radiation damage response of a material is determined by the fate of these excess Frenkel pair defects in the lattice. The objective is to understand the electronic and atomic structure of Fe/Y{sub 2}O{sub 3} interface and segregation behavior of the alloying elements at the interface. The significance of the results of this report are: (1) Provides a science based approach to design new radiation resistant materials. Obtained two controlling parameters - Dislocation density (composition, orientation relationship) and Oxygen partial pressure; (2) Applicable to any other metal/oxide interfaces (both functional and structural properties at the interface) - (a) Nano Catalysts: Oxide-supported metal catalysts Ni/ZrO{sub 2}, (b) Thermal barrier coatings (Ni/Al{sub 2}O{sub 3}), (c) Corrosion of metals and alloys.

Structure and Properties of the Fe/Y2O3 Interface from First Principles Calculations

International Nuclear Information System (INIS)

Choudhury, Samrat; Stanek, Christopher R.; Uberuaga, Blas P.

2012-01-01

Fundamentals of radiation damage are: (1) Formation of Frenkel pair (interstitial-vacancy pair) defects in the lattice; (2) Concentration of Frenkel pair defects >>> thermal equilibrium thermodynamic concentration; and (3) The radiation damage response of a material is determined by the fate of these excess Frenkel pair defects in the lattice. The objective is to understand the electronic and atomic structure of Fe/Y 2 O 3 interface and segregation behavior of the alloying elements at the interface. The significance of the results of this report are: (1) Provides a science based approach to design new radiation resistant materials. Obtained two controlling parameters - Dislocation density (composition, orientation relationship) and Oxygen partial pressure; (2) Applicable to any other metal/oxide interfaces (both functional and structural properties at the interface) - (a) Nano Catalysts: Oxide-supported metal catalysts Ni/ZrO 2 , (b) Thermal barrier coatings (Ni/Al 2 O 3 ), (c) Corrosion of metals and alloys.

Surface forces between rough and topographically structured interfaces

DEFF Research Database (Denmark)

Thormann, Esben

2017-01-01

Within colloidal science, direct or indirect measurements of surface forces represent an important tool for developing a fundamental understanding of colloidal systems, as well as for predictions of the stability of colloidal suspensions. While the general understanding of colloidal interactions...... and manufactured materials, which possess topographical variations. Further, with technological advances in nanotechnology, fabrication of nano- or micro-structured surfaces has become increasingly important for many applications, which calls for a better understanding of the effect of surface topography...... on the interaction between interfaces. This paper presents a review of the current state of understanding of the effect of surface roughness on DLVO forces, as well as on the interactions between topographically structured hydrophobic surfaces in water. While the first case is a natural choice because it represents...

3-Dimensional atomic scale structure of the ionic liquid-graphite interface elucidated by AM-AFM and quantum chemical simulations

Science.gov (United States)

Page, Alister J.; Elbourne, Aaron; Stefanovic, Ryan; Addicoat, Matthew A.; Warr, Gregory G.; Voïtchovsky, Kislon; Atkin, Rob

2014-06-01

In situ amplitude modulated atomic force microscopy (AM-AFM) and quantum chemical simulations are used to resolve the structure of the highly ordered pyrolytic graphite (HOPG)-bulk propylammonium nitrate (PAN) interface with resolution comparable with that achieved for frozen ionic liquid (IL) monolayers using STM. This is the first time that (a) molecular resolution images of bulk IL-solid interfaces have been achieved, (b) the lateral structure of the IL graphite interface has been imaged for any IL, (c) AM-AFM has elucidated molecular level structure immersed in a viscous liquid and (d) it has been demonstrated that the IL structure at solid surfaces is a consequence of both thermodynamic and kinetic effects. The lateral structure of the PAN-graphite interface is highly ordered and consists of remarkably well-defined domains of a rhomboidal superstructure composed of propylammonium cations preferentially aligned along two of the three directions in the underlying graphite lattice. The nanostructure is primarily determined by the cation. Van der Waals interactions between the propylammonium chains and the surface mean that the cation is enriched in the surface layer, and is much less mobile than the anion. The presence of a heterogeneous lateral structure at an ionic liquid-solid interface has wide ranging ramifications for ionic liquid applications, including lubrication, capacitive charge storage and electrodeposition.In situ amplitude modulated atomic force microscopy (AM-AFM) and quantum chemical simulations are used to resolve the structure of the highly ordered pyrolytic graphite (HOPG)-bulk propylammonium nitrate (PAN) interface with resolution comparable with that achieved for frozen ionic liquid (IL) monolayers using STM. This is the first time that (a) molecular resolution images of bulk IL-solid interfaces have been achieved, (b) the lateral structure of the IL graphite interface has been imaged for any IL, (c) AM-AFM has elucidated molecular level

Understanding and Design of Polymer Device Interfaces

Energy Technology Data Exchange (ETDEWEB)

Kahn, Antoine [Princeton Univ., NJ (United States)

2015-10-26

The research performed under grant DE-FG02-04ER46165 between May 2008 and April 2011 focused on the understanding and control of interfaces of organic semiconductors in general, and polymer interfaces more specifically. This work was a joined effort by three experimentalists and a theoretician. Emphasis was placed on the determination of the electronic structure of these interfaces, i.e. the relative energy position of molecular levels across these interfaces. From these electronic structures depend the injection, extraction and transport of charge carriers into, from and across, respectively, all (opto)electronic devices made of these semiconductors. A significant fraction of our work focused on ways to modify and optimize interfaces, for example via chemical doping of the semiconductors to reduce interface energy barriers or via deposition of ultra-thin work function-reducing polymer or self-assembled monolayers of dipolar molecules. Another significant fraction of our work was devoted to exploring alternate and unconventional interface formation methods, in particular the soft-contact lamination of both metal contacts and polymer overlayers on top of polymer films. These methods allowed us to better understand the impact of hot metal atom evaporation on a soft organic surface, as well as the key mechanisms that control the energetics of polymer/polymer heterojunctions. Finally, a significant fraction of the research was directed to understanding the electronic structure of buried polymer heterojunctions, in particular within donor/acceptor blends of interest in organic photovoltaic applications. The work supported by this grant resulted in 17 publications in some of the best peer-reviewed journals of the field, as well as numerous presentations at US and international conferences.

User interfaces for computational science: A domain specific language for OOMMF embedded in Python

Science.gov (United States)

Beg, Marijan; Pepper, Ryan A.; Fangohr, Hans

2017-05-01

Computer simulations are used widely across the engineering and science disciplines, including in the research and development of magnetic devices using computational micromagnetics. In this work, we identify and review different approaches to configuring simulation runs: (i) the re-compilation of source code, (ii) the use of configuration files, (iii) the graphical user interface, and (iv) embedding the simulation specification in an existing programming language to express the computational problem. We identify the advantages and disadvantages of different approaches and discuss their implications on effectiveness and reproducibility of computational studies and results. Following on from this, we design and describe a domain specific language for micromagnetics that is embedded in the Python language, and allows users to define the micromagnetic simulations they want to carry out in a flexible way. We have implemented this micromagnetic simulation description language together with a computational backend that executes the simulation task using the Object Oriented MicroMagnetic Framework (OOMMF). We illustrate the use of this Python interface for OOMMF by solving the micromagnetic standard problem 4. All the code is publicly available and is open source.

Structural Interfaces and Attachments in Biology

CERN Document Server

Birman, Victor; Genin, Guy

2013-01-01

Attachment of dissimilar materials in engineering and surgical practice is a perennial challenge. Bimaterial attachment sites are common locations for injury, repeated injury, and mechanical failure. Nature presents several highly effective solutions to the challenge of bimaterial attachment that differ from those found in engineering practice. Structural Interfaces and Attachments in Biology describes the attachment of dissimilar materials from multiple perspectives. The text will simultaneously elucidate natural bimaterial attachments and outline engineering principles underlying successful attachments to the communities of tissue engineers and surgeons. Included an in-depth analysis of the biology of attachments in the body and mechanisms by which robust attachments are formed, a review of current concepts of attaching dissimilar materials in surgical practice and a discussion of bioengineering approaches that are currently being developed. This book also: Provides the first comprehensive treatment of phys...

In situ surface X-ray diffraction studies of the copper-electrolyte interface. Atomic structure and homoepitaxial grwoth

Energy Technology Data Exchange (ETDEWEB)

Golks, Frederik

2011-05-19

Copper electrodeposition is the predominantly used technique for on-chip wiring in the fabrication of ultra-large scale integrated (ULSI) microchips. In this 'damascene copper electroplating' process, multicomponent electrolytes containing organic additives realize void-free filling of trenches with high aspect ratio ('superconformal deposition'). Despite manifold studies, motivated by the continuous trend to shrink wiring dimensions and thus the demand of optimized plating baths, detailed knowledge on the growth mechanism - in presence and absence of additives - is still lacking. Using a recently developed hanging meniscus X-ray transmission cell, brilliant synchrotron x-rays and a fast, one-dimensional detector system, unique real-time in situ surface X-ray diffraction studies of copper electrodeposition were performed under realistic reaction conditions, approaching rates of technological relevance. Preparatory measurements of the electrochemical dissolution of Au(001) in chloride-containing electrolyte demonstrated the capability of this powerful technique, specifically the possibility to follow atomic-scale deposition or dissolution processes with a time resolution down to five milliseconds. The electrochemical as well as structural characterization of the Cu(001)- and Cu(111)-electrolyte interfaces provided detailed insight into the complex atomic-scale structures in presence of specifically adsorbed chloride on these surfaces. The interface of Cu(001) in chloride-containing electrolyte exhibits a continuous surface phase transition of a disordered Cl adlayer to a c(2 x 2) Cl adlayer with increasing potential. The latter was found to induce a small vertical corrugation of substrate atoms, which can be ascribed to lattice relaxations induced by the presence of coadsorbed water molecules and cations in the outer part of the electrochemical double layer. The study of the specific adsorption of chloride on Cu(111) from acidic aqueous

In situ surface X-ray diffraction studies of the copper-electrolyte interface. Atomic structure and homoepitaxial grwoth

Energy Technology Data Exchange (ETDEWEB)

Golks, Frederik

2011-05-19

Copper electrodeposition is the predominantly used technique for on-chip wiring in the fabrication of ultra-large scale integrated (ULSI) microchips. In this 'damascene copper electroplating' process, multicomponent electrolytes containing organic additives realize void-free filling of trenches with high aspect ratio ('superconformal deposition'). Despite manifold studies, motivated by the continuous trend to shrink wiring dimensions and thus the demand of optimized plating baths, detailed knowledge on the growth mechanism - in presence and absence of additives - is still lacking. Using a recently developed hanging meniscus X-ray transmission cell, brilliant synchrotron x-rays and a fast, one-dimensional detector system, unique real-time in situ surface X-ray diffraction studies of copper electrodeposition were performed under realistic reaction conditions, approaching rates of technological relevance. Preparatory measurements of the electrochemical dissolution of Au(001) in chloride-containing electrolyte demonstrated the capability of this powerful technique, specifically the possibility to follow atomic-scale deposition or dissolution processes with a time resolution down to five milliseconds. The electrochemical as well as structural characterization of the Cu(001)- and Cu(111)-electrolyte interfaces provided detailed insight into the complex atomic-scale structures in presence of specifically adsorbed chloride on these surfaces. The interface of Cu(001) in chloride-containing electrolyte exhibits a continuous surface phase transition of a disordered Cl adlayer to a c(2 x 2) Cl adlayer with increasing potential. The latter was found to induce a small vertical corrugation of substrate atoms, which can be ascribed to lattice relaxations induced by the presence of coadsorbed water molecules and cations in the outer part of the electrochemical double layer. The study of the specific adsorption of chloride on Cu(111) from acidic aqueous electrolyte revealed a

Structure, interface abruptness and strain relaxation in self-assisted grown InAs/GaAs nanowires

Energy Technology Data Exchange (ETDEWEB)

Frigeri, Cesare, E-mail: frigeri@imem.cnr.it [CNR-IMEM Institute, Parma (Italy); Scarpellini, David [L–NESS and Dept. Materials Science, University of Milano Bicocca, Milano (Italy); Department of Industrial Engineering University of Rome Tor Vergata, Rome (Italy); Fedorov, Alexey [LNESS and CNR-IFN, Como (Italy); Bietti, Sergio; Somaschini, Claudio [L–NESS and Dept. Materials Science, University of Milano Bicocca, Milano (Italy); Grillo, Vincenzo [CNR-IMEM Institute, Parma (Italy); CNR-S3-NANO Center, Modena (Italy); Esposito, Luca; Salvalaglio, Marco; Marzegalli, Anna; Montalenti, Francesco [L–NESS and Dept. Materials Science, University of Milano Bicocca, Milano (Italy); Sanguinetti, Stefano [L–NESS and Dept. Materials Science, University of Milano Bicocca, Milano (Italy); LNESS and CNR-IFN, Como (Italy)

2017-02-15

Highlights: • We study 2 critical issues (interface abruptness and strain release) in InAs/GaAs NWs. • Structural and chemical interface sharpness ≤1.5 nm, better than in previous reports. • Simultaneous elastic and plastic relaxation is shown that agrees with FEM simulations. • Structural, chemical and strain release investigations were performed by STEM. • New MBE self-seeded method whereby InAs is grown by splitting In and As depositions. - Abstract: The structure, interface abruptness and strain relaxation in InAs/GaAs nanowires grown by molecular beam epitaxy in the Ga self-catalysed mode on (111) Si have been investigated by transmission electron microscopy. The nanowires had the zincblende phase. The InAs/GaAs interface was atomically and chemically sharp with a width around 1.5 nm, i.e. significantly smaller than previously reported values. This was achieved by the consumption of the Ga droplet and formation of a flat top facet of the GaAs followed by the growth of InAs by splitting the depositions of In and As. Both elastic and plastic strain relaxation took place simultaneously. Experimental TEM results about strain relaxation very well agree with linear elasticity theory calculations by the finite element methods.

Structure, interface abruptness and strain relaxation in self-assisted grown InAs/GaAs nanowires

International Nuclear Information System (INIS)

Frigeri, Cesare; Scarpellini, David; Fedorov, Alexey; Bietti, Sergio; Somaschini, Claudio; Grillo, Vincenzo; Esposito, Luca; Salvalaglio, Marco; Marzegalli, Anna; Montalenti, Francesco; Sanguinetti, Stefano

2017-01-01

Highlights: • We study 2 critical issues (interface abruptness and strain release) in InAs/GaAs NWs. • Structural and chemical interface sharpness ≤1.5 nm, better than in previous reports. • Simultaneous elastic and plastic relaxation is shown that agrees with FEM simulations. • Structural, chemical and strain release investigations were performed by STEM. • New MBE self-seeded method whereby InAs is grown by splitting In and As depositions. - Abstract: The structure, interface abruptness and strain relaxation in InAs/GaAs nanowires grown by molecular beam epitaxy in the Ga self-catalysed mode on (111) Si have been investigated by transmission electron microscopy. The nanowires had the zincblende phase. The InAs/GaAs interface was atomically and chemically sharp with a width around 1.5 nm, i.e. significantly smaller than previously reported values. This was achieved by the consumption of the Ga droplet and formation of a flat top facet of the GaAs followed by the growth of InAs by splitting the depositions of In and As. Both elastic and plastic strain relaxation took place simultaneously. Experimental TEM results about strain relaxation very well agree with linear elasticity theory calculations by the finite element methods.

Direct Atomic Scale Observation of the Structure and Chemistry of Order/Disorder Interfaces

National Research Council Canada - National Science Library

Srinivasan, R; Banerjee, R; Hwang, J. Y; Viswanathan, G. B; Tiley, J; Fraser, H. L

2008-01-01

... distributed ordered intermetallic precipitates within a disordered matrix. The structure and chemistry at the precipitate/matrix interface plays a critical role in determining the effectiveness of the strengthening mechanism...

Silicon Σ13(5 0 1) grain boundary interface structure determined by bicrystal Bragg rod X-ray scattering

International Nuclear Information System (INIS)

Howes, P.B.; Rhead, S.; Roy, M.; Nicklin, C.L.; Rawle, J.L.; Norris, C.A.

2013-01-01

The atomic structure of the silicon Σ13(5 0 1) symmetric tilt grain boundary interface has been determined using Bragg rod X-ray scattering. In contrast to conventional structural studies of grain boundary structure using transmission electron microscopy, this approach allows the non-destructive measurement of macroscopic samples. The interface was found to have a single structure that is fully fourfold coordinated. X-ray diffraction data were measured at Beamline I07 at the Diamond Light Source

Multi-scale structuration of the electrode-electrolyte interface for applications in bio-electro-catalysis; Structuration multi-echelle de l'interface electrode-electrolyte pour des applications en bioelectrocatalyse

Energy Technology Data Exchange (ETDEWEB)

Kuhn, A. [Bordeaux-1 Univ., LACReM, ENSCPB, 33 - Pessac (France)

2006-07-01

In this work, two approaches have been combined to elaborate bio-functionalized interfaces having an original structure and well defined at several characteristic scales. These two approaches are 1)the growth of conducting or non conducting materials through organized structures and 2)the chemistry of non-covalent intermolecular bonds leading to the assembling of molecules towards interfacial structures having greatest size. With a deep physico-chemical characterization, it has been possible to understand the properties of these multi-scale structures and to propose different applications fields as for instance bio-electro-catalysis or photovoltaic cells. (O.M.)

An investigation of the fluid-structure interaction of piston/cylinder interface

Science.gov (United States)

Pelosi, Matteo

The piston/cylinder lubricating interface represents one of the most critical design elements of axial piston machines. Being a pure hydrodynamic bearing, the piston/cylinder interface fulfills simultaneously a bearing and sealing function under oscillating load conditions. Operating in an elastohydrodynamic lubrication regime, it also represents one of the main sources of power loss due to viscous friction and leakage flow. An accurate prediction of the time changing tribological interface characteristics in terms of fluid film thickness, dynamic pressure field, load carrying ability and energy dissipation is necessary to create more efficient interface designs. The aim of this work is to deepen the understanding of the main physical phenomena defining the piston/cylinder fluid film and to discover the impact of surface elastic deformations and heat transfer on the interface behavior. For this purpose, a unique fully coupled multi-body dynamics model has been developed to capture the complex fluid-structure interaction phenomena affecting the non-isothermal fluid film conditions. The model considers the squeeze film effect due to the piston micro-motion and the change in fluid film thickness due to the solid boundaries elastic deformations caused by the fluid film pressure and by the thermal strain. The model has been verified comparing the numerical results with measurements taken on special designed test pumps. The fluid film calculated dynamic pressure and temperature fields have been compared. Further validation has been accomplished comparing piston/cylinder axial viscous friction forces with measured data. The model has been used to study the piston/cylinder interface behavior of an existing axial piston unit operating at high load conditions. Numerical results are presented in this thesis.

Structure and Dynamics of Interfaces: Drops and Films

Science.gov (United States)

Mann, J. Adin, Jr.; Mann, Elizabeth K.; Meyer, William V.; Neumann, A. Wilhelm; Tavana, Hossein

2015-01-01

We aim to acquire measurements of the structure and dynamics of certain liquid-fluid interfaces using an ensemble of techniques in collaboration: (1) Total internal reflection (TIR) Surface light scattering spectroscopy (SLSS), (2) Brewster angle microscopy (BAM), and (3) Drop-shape analysis. SLSS and BAM can be done on a shared interfacial footprint. Results using a 50-50 mixture of pentane-isohexane, which extends the range of NASA's Confined Vapor Bubble (CVB) experiment, yield surface tension results that differ from the expected Langmuir Fit. These results were confirmed using both the SLSS and drop-shape analysis approaches.

Wetting, meniscus structure, and capillary interactions of microspheres bound to a cylindrical liquid interface.

Science.gov (United States)

Kim, Paul Y; Dinsmore, Anthony D; Hoagland, David A; Russell, Thomas P

2018-03-14

Wetting, meniscus structure, and capillary interactions for polystyrene microspheres deposited on constant curvature cylindrical liquid interfaces, constructed from nonvolatile ionic or oligomeric liquids, were studied by optical interferometry and optical microscopy. The liquid interface curvature resulted from the preferential wetting of finite width lines patterned onto planar silicon substrates. Key variables included sphere diameter, nominal (or average) contact angle, and deviatoric interfacial curvature. Menisci adopted the quadrupolar symmetry anticipated by theory, with interfacial deformation closely following predicted dependences on sphere diameter and nominal contact angle. Unexpectedly, the contact angle was not constant locally around the contact line, the nominal contact angle varied among seemingly identical spheres, and the maximum interface deviation did not follow the predicted dependence on deviatoric interfacial curvature. Instead, this deviation was up to an order-of-magnitude larger than predicted. Trajectories of neighboring microspheres visually manifested quadrupole-quadrupole interactions, eventually producing square sphere packings that foreshadow interfacial assembly as a potential route to hierarchical 2D particle structures.

A new relational database structure and online interface for the HITRAN database

International Nuclear Information System (INIS)

Hill, Christian; Gordon, Iouli E.; Rothman, Laurence S.; Tennyson, Jonathan

2013-01-01

A new format for the HITRAN database is proposed. By storing the line-transition data in a number of linked tables described by a relational database schema, it is possible to overcome the limitations of the existing format, which have become increasingly apparent over the last few years as new and more varied data are being used by radiative-transfer models. Although the database in the new format can be searched using the well-established Structured Query Language (SQL), a web service, HITRANonline, has been deployed to allow users to make most common queries of the database using a graphical user interface in a web page. The advantages of the relational form of the database to ensuring data integrity and consistency are explored, and the compatibility of the online interface with the emerging standards of the Virtual Atomic and Molecular Data Centre (VAMDC) project is discussed. In particular, the ability to access HITRAN data using a standard query language from other websites, command line tools and from within computer programs is described. -- Highlights: • A new, interactive version of the HITRAN database is presented. • The data is stored in a structured fashion in a relational database. • The new HITRANonline interface offers increased functionality and easier error correction

Nanostructured interfaces with site-specific bioreceptors for immunosensing

Energy Technology Data Exchange (ETDEWEB)

Paiva, Telmo O.; Almeida, Inês; Marquês, Joaquim T. [Centro de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, Edifício C8, 1749-016 Lisboa (Portugal); Liu, Wei [NML, Institute of Mechanics, Chinese Academy of Sciences, Beijing, 100190 (China); Institute of Microelectronics, Tsinghua University, Beijing 100084 (China); Niu, Yu [NML, Institute of Mechanics, Chinese Academy of Sciences, Beijing, 100190 (China); Jin, Gang, E-mail: gajin@imech.ac.cn [NML, Institute of Mechanics, Chinese Academy of Sciences, Beijing, 100190 (China); School of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049 (China); Viana, Ana S., E-mail: anaviana@fc.ul.pt [Centro de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, Edifício C8, 1749-016 Lisboa (Portugal)

2017-08-01

Highlights: • Innovative and simple strategy to create sensitive immunosensing platforms. • Gold surface modification with dithiocarbamate nanoconjugates of protein A. • CS{sub 2} strongly adsorbed on gold able to block protein nonspecific adsorption. • High performance for antigen detection by properly oriented antibodies. - Abstract: In this work, we propose a simple and effective approach to build nanostructured immunosensor platforms. The one-step strategy relies on i) the in situ formation of dithiocarbamates from the reaction between carbon disulfide and amine groups, present on protein A, ii) their attachment to gold nanoparticles (AuNPs), and iii) the linkage of the modified AuNPs to the electrode surface, which depends on the strong interaction between gold substrates and sulfur moieties. AuNPs and protein A are used to increase the surface coverage of Immunoglobulin G (IgG) and promote the oriented immobilization of the antibodies on the immunosensing interface. The modified gold surfaces with biomolecules were thoroughly characterized by a combination of techniques: UV–vis spectrophotometry, conventional ellipsometry and atomic force microscopy. The immunosensor performance was assessed in real-time, by surface plasmon resonance and by the highly sensitive total internal reflection imaging ellipsometry, through the specific biorecognition between anti-IgG and the immobilized IgG molecules. We demonstrate that the presence of AuNPs improves the sensitivity of the anti-IgG specific detection, whereas the presence of co-adsorbed CS{sub 2} is responsible for blocking the undesired protein nonspecific adsorption to the gold substrate. Overall, we report a simple and innovative one-step method, to chemically modify gold surfaces with protein A and AuNPs, able to specifically detect antigen/antibody interactions with capability of preventing protein nonspecific adsorption.

Synchrotron radiation studies of inorganic-organic semiconductor interfaces

International Nuclear Information System (INIS)

Evans, D.A.; Steiner, H.J.; Vearey-Roberts, A.R.; Bushell, A.; Cabailh, G.; O'Brien, S.; Wells, J.W.; McGovern, I.T.; Dhanak, V.R.; Kampen, T.U.; Zahn, D.R.T.; Batchelor, D.

2003-01-01

Organic semiconductors (polymers and small molecules) are widely used in electronic and optoelectronic technologies. Many devices are based on multilayer structures where interfaces play a central role in device performance and where inorganic semiconductor models are inadequate. Synchrotron radiation techniques such as photoelectron spectroscopy (PES), near-edge X-ray absorption fine structure (NEXAFS) and X-ray standing wave spectroscopy (XSW) provide a powerful means of probing the structural, electronic and chemical properties of these interfaces. The surface-specificity of these techniques allows key properties to be monitored as the heterostructure is fabricated. This methodology has been directed at the growth of hybrid organic-inorganic semiconductor interfaces involving copper phthalocyanine as the model organic material and InSb and GaAs as the model inorganic semiconductor substrates. Core level PES has revealed that these interfaces are abrupt and chemically inert due to the weak bonding between the molecules and the inorganic semiconductor. NEXAFS studies have shown that there is a preferred orientation of the molecules within the organic semiconductor layers. The valence band offsets for the heterojunctions have been directly measured using valence level PES and were found to be very different for copper phthalocyanine on InSb and GaAs (0.7 and -0.3 eV respectively) although an interface dipole is present in both cases

Operator/regulator interface: Organizational structure and responsibilities

Energy Technology Data Exchange (ETDEWEB)

Wiebe, J S [American Electric Power Service Corp. (United States)

1997-09-01

In the context of promotion of safety culture for the nuclear power plants the following aspects are briefly described: operator/regulator interface regulatory organization; policy making body; operating organization; regulatory interface.

Wave structure and transfer mechanisms at the interface of liquid films (a bibliographic synthesis)

International Nuclear Information System (INIS)

Spindler, Bertrand.

1978-10-01

The flow of a liquid film occurs in many industrial apparatuses. The waves which propagate at the film interface increase the momentum, mass and heat transfer rates of the system. The interface structure is studied; the different patterns of waves with their parameters (shape, amplitude, wavelength, celerity, frequency) and phenomena such as droplet entrainment are examined. An explanation is then given for the increase of transfer rates [fr

ASC-PROBA Interface Control Document

DEFF Research Database (Denmark)

Betto, Maurizio; Jørgensen, John Leif; Jørgensen, Finn E

1999-01-01

of Automation of the Technical University of Denmark. The document is structured as follows. First we present the ASC - heritage, system description, performance - then we address more specifically the environmental properties, like the EMC compatibility and thermal characteristics, and the design...... and reliability issues. Section 6 deals with the testing and the calibration procedures and in section 7 the mechanical and electrical interfaces are given. In section 8 and 9 we address issues like manufacturing, transportation and storage and to conclude we review the ASC specifications against the PROBA...

Physics of Schottky-barrier change by segregation and structural disorder at metal/Si interfaces: First-principles study

International Nuclear Information System (INIS)

Nakayama, T.; Kobinata, K.

2012-01-01

Schottky-barrier changes by the segregation and structural disorder are studied using the first-principles calculations and adopting Au/Si interface. The Schottky barrier for electrons simply decreases as increasing the valency of segregated atoms from II to VI families, which variation is shown closely related to how the Si atoms are terminated at the interface. On the other hand, the structural disorders (defects) prefer to locate near the interface and the Schottky barrier for hole carriers does not change in cases of Si vacancy and Au substitution, while it increases in cases of Si and Au interstitials reflecting the appearance of Si dangling bonds.

Fluctuation in Interface and Electronic Structure of Single-Molecule Junctions Investigated by Current versus Bias Voltage Characteristics.

Science.gov (United States)

Isshiki, Yuji; Fujii, Shintaro; Nishino, Tomoaki; Kiguchi, Manabu

2018-03-14

Structural and electronic detail at the metal-molecule interface has a significant impact on the charge transport across the molecular junctions, but its precise understanding and control still remain elusive. On the single-molecule scale, the metal-molecule interface structures and relevant charge transport properties are subject to fluctuation, which contain the fundamental science of single-molecule transport and implication for manipulability of the transport properties in electronic devices. Here, we present a comprehensive approach to investigate the fluctuation in the metal-molecule interface in single-molecule junctions, based on current-voltage ( I- V) measurements in combination with first-principles simulation. Contrary to conventional molecular conductance studies, this I- V approach provides a correlated statistical description of both the degree of electronic coupling across the metal-molecule interface and the molecular orbital energy level. This statistical approach was employed to study fluctuation in single-molecule junctions of 1,4-butanediamine (DAB), pyrazine (PY), 4,4'-bipyridine (BPY), and fullerene (C 60 ). We demonstrate that molecular-dependent fluctuation of σ-, π-, and π-plane-type interfaces can be captured by analyzing the molecular orbital (MO) energy level under mechanical perturbation. While the MO level of DAB with the σ-type interface shows weak distance dependence and fluctuation, the MO level of PY, BPY, and C 60 features unique distance dependence and molecular-dependent fluctuation against the mechanical perturbation. The MO level of PY and BPY with the σ+π-type interface increases with the increase in the stretch distance. In contrast, the MO level of C 60 with the π-plane-type interface decreases with the increase in the stretching perturbation. This study provides an approach to resolve the structural and electronic fluctuation in the single-molecule junctions and insight into the molecular-dependent fluctuation in

In-Situ TEM Study of Interface Sliding and Migration in an Ultrafine Lamellar Structure

Energy Technology Data Exchange (ETDEWEB)

Hsiung, L M

2005-12-06

The instability of interfaces in an ultrafine TiAl-({gamma})/Ti{sub 3}Al-({alpha}{sub 2}) lamellar structure by straining at room temperature has been investigated using in-situ straining techniques performed in a transmission electron microscope. The purpose of this study is to obtain experimental evidence to support the creep mechanisms based upon the interface sliding in association with a cooperative movement of interfacial dislocations previously proposed to interpret the nearly linear creep behavior observed from ultrafine lamellar TiAl alloys. The results have revealed that both the sliding and migration of lamellar interfaces can take place simultaneously as a result of the cooperative movement of interfacial dislocations.

Oligomerisation status and evolutionary conservation of interfaces of protein structural domain superfamilies.

Science.gov (United States)

Sukhwal, Anshul; Sowdhamini, Ramanathan

2013-07-01

Protein-protein interactions are important in carrying out many biological processes and functions. These interactions may be either permanent or of temporary nature. Several studies have employed tools like solvent accessibility and graph theory to identify these interactions, but still more studies need to be performed to quantify and validate them. Although we now have many databases available with predicted and experimental results on protein-protein interactions, we still do not have many databases which focus on providing structural details of the interacting complexes, their oligomerisation state and homologues. In this work, protein-protein interactions have been thoroughly investigated within the structural regime and quantified for their strength using calculated pseudoenergies. The PPCheck server, an in-house webserver, has been used for calculating the pseudoenergies like van der Waals, hydrogen bonds and electrostatic energy based on distances between atoms of amino acids from two interacting proteins. PPCheck can be visited at . Based on statistical data, as obtained by studying established protein-protein interacting complexes from earlier studies, we came to a conclusion that an average protein-protein interface consisted of about 51 to 150 amino acid residues and the generalized energy per residue ranged from -2 kJ mol(-1) to -6 kJ mol(-1). We found that some of the proteins have an exceptionally higher number of amino acids at the interface and it was purely because of their elaborate interface or extended topology i.e. some of their secondary structure regions or loops were either inter-mixing or running parallel to one another or they were taking part in domain swapping. Residue networks were prepared for all the amino acids of the interacting proteins involved in different types of interactions (like van der Waals, hydrogen-bonding, electrostatic or intramolecular interactions) and were analysed between the query domain-interacting partner pair

User interfaces for computational science: A domain specific language for OOMMF embedded in Python

Directory of Open Access Journals (Sweden)

Marijan Beg

2017-05-01

Full Text Available Computer simulations are used widely across the engineering and science disciplines, including in the research and development of magnetic devices using computational micromagnetics. In this work, we identify and review different approaches to configuring simulation runs: (i the re-compilation of source code, (ii the use of configuration files, (iii the graphical user interface, and (iv embedding the simulation specification in an existing programming language to express the computational problem. We identify the advantages and disadvantages of different approaches and discuss their implications on effectiveness and reproducibility of computational studies and results. Following on from this, we design and describe a domain specific language for micromagnetics that is embedded in the Python language, and allows users to define the micromagnetic simulations they want to carry out in a flexible way. We have implemented this micromagnetic simulation description language together with a computational backend that executes the simulation task using the Object Oriented MicroMagnetic Framework (OOMMF. We illustrate the use of this Python interface for OOMMF by solving the micromagnetic standard problem 4. All the code is publicly available and is open source.

Multiscale mechanics of hierarchical structure/property relationships in calcified tissues and tissue/material interfaces

International Nuclear Information System (INIS)

Katz, J. Lawrence; Misra, Anil; Spencer, Paulette; Wang, Yong; Bumrerraj, Sauwanan; Nomura, Tsutomu; Eppell, Steven J.; Tabib-Azar, Massood

2007-01-01

This paper presents a review plus new data that describes the role hierarchical nanostructural properties play in developing an understanding of the effect of scale on the material properties (chemical, elastic and electrical) of calcified tissues as well as the interfaces that form between such tissues and biomaterials. Both nanostructural and microstructural properties will be considered starting with the size and shape of the apatitic mineralites in both young and mature bovine bone. Microstructural properties for human dentin and cortical and trabecular bone will be considered. These separate sets of data will be combined mathematically to advance the effects of scale on the modeling of these tissues and the tissue/biomaterial interfaces as hierarchical material/structural composites. Interfacial structure and properties to be considered in greatest detail will be that of the dentin/adhesive (d/a) interface, which presents a clear example of examining all three material properties, (chemical, elastic and electrical). In this case, finite element modeling (FEA) was based on the actual measured values of the structure and elastic properties of the materials comprising the d/a interface; this combination provides insight into factors and mechanisms that contribute to premature failure of dental composite fillings. At present, there are more elastic property data obtained by microstructural measurements, especially high frequency ultrasonic wave propagation (UWP) and scanning acoustic microscopy (SAM) techniques. However, atomic force microscopy (AFM) and nanoindentation (NI) of cortical and trabecular bone and the dentin-enamel junction (DEJ) among others have become available allowing correlation of the nanostructural level measurements with those made on the microstructural level

Strain induced atomic structure at the Ir-doped LaAlO3/SrTiO3 interface.

Science.gov (United States)

Lee, M; Arras, R; Warot-Fonrose, B; Hungria, T; Lippmaa, M; Daimon, H; Casanove, M J

2017-11-01

The structure of Ir-doped LaAlO 3 /SrTiO 3 (001) interfaces was investigated on the atomic scale using probe-corrected transmission electron microscopy in high-angle annular dark-field scanning mode (HAADF-STEM) and electron energy loss spectroscopy (EELS), combined with first-principles calculations. We report the evolution of the strain state experimentally measured in a 5 unit-cell thick LaAlO 3 film as a function of the Ir concentration in the topmost SrTiO 3 layer. It is shown that the LaAlO 3 layers remain fully elastically strained up to 3% of Ir doping, whereas a higher doping level seems to promote strain relaxation through enhanced cationic interdiffusion. The observed differences between the energy loss near edge structure (ELNES) of Ti-L 2,3 and O-K edges at non-doped and Ir-doped interfaces are consistent with the location of the Ir dopants at the interface, up to 3% of Ir doping. These findings, supported by the results of density functional theory (DFT) calculations, provide strong evidence that the effect of dopant concentrations on the properties of this kind of interface should not be analyzed without obtaining essential information from the fine structural and chemical analysis of the grown structures.

Structure, composition and function of interfaces in ceramic fibre/matrix composites

International Nuclear Information System (INIS)

Pippel, E.

1993-01-01

Improving the properties of fibre reinforced ceramics and glasses by optimizing their microstructure requires the knowledge of this structure down to the atomic level. In these materials energy-dissipative processes during fracture particularly act within an interface layer or layer system between fibre and matrix which can either be produced by fibre coating, or which develops during the processing of the composites. Examples are presented of the microstructural phenomena of such layers revealed by HVEM and HREM and complemented by microchemical information via a nanoscale EDXS equipment. The investigations are carried out on Nicalon fibres in Duran glass as well as on Tyranno, Nicalon and carbon fibres in different SiC-matrices. Finally, a process is discussed which may control the important interface parameters. (orig.)

Pairwise structure alignment specifically tuned for surface pockets and interaction interfaces

KAUST Repository

Cui, Xuefeng; Naveed, Hammad; Gao, Xin

2015-01-01

that are not limited to backbone fragments, and by employing a maximum weighted bipartite matching solver from the beginning of the alignment process. In addition, our methods incorporate similarities of sequentially and structurally remote residues that potentially

Self-consistent electronic-structure calculations for interface geometries

International Nuclear Information System (INIS)

Sowa, E.C.; Gonis, A.; MacLaren, J.M.; Zhang, X.G.

1992-01-01

This paper describes a technique for computing self-consistent electronic structures and total energies of planar defects, such as interfaces, which are embedded in an otherwise perfect crystal. As in the Layer Korringa-Kohn-Rostoker approach, the solid is treated as a set of coupled layers of atoms, using Bloch's theorem to take advantage of the two-dimensional periodicity of the individual layers. The layers are coupled using the techniques of the Real-Space Multiple-Scattering Theory, avoiding artificial slab or supercell boundary conditions. A total-energy calculation on a Cu crystal, which has been split apart at a (111) plane, is used to illustrate the method

Probing buried solid-solid interfaces in magnetic multilayer structures and other nanostructures using spectroscopy excited by soft x-ray standing waves

International Nuclear Information System (INIS)

Yang, S.-H.; Mun, B.S.; Mannella, N.; Sell, B.; Ritchey, S.B.; Fadley, C.S.; Pham, L.; Nambu, A.; Watanabe, M.

2004-01-01

Full text: Buried solid-solid interfaces are becoming increasingly more important in all aspects of nanoscience, and we here dis- cuss the st applications of a new method for selectively studying them with the vuv/soft x-ray spectroscopies. As specific examples, magnetic multilayer structures represent key elements of current developments in spintronics, including giant magnetoresistance, exchange bias, and magnetic tunnel resistance. The buried interfaces in such structures are of key importance to their performance, but have up to now been difficult to study selectively with these spectroscopies. This novel method involves excitation of photoelectrons or fluorescent x-rays with soft x-ray standing waves created by Bragg reflection from a multilayer mirror substrate on which the sample is grown. We will discuss core and valence photoemission, as well soft x-ray emission, results from applying this method to multilayer structures relevant to both giant magnetoresistance (Fe/Cr-[2]) and magnetic tunnel junctions (Al 2 O 3 /FeCo) , including magnetic dichroism measurements. Work supported by the Director, Of e of Science, Of e of Basic Energy Sciences, Materials Science and Engineering Division, U.S. Department of Energy, Contract No. DE-AC03-76SF000

Structure of the liquid-vapor interface of a dilute ternary alloy: Pb and In in Ga

International Nuclear Information System (INIS)

Yang Bin; Li Dongxu; Rice, Stuart A.

2003-01-01

We report the results of experimental studies of how the competition between two solutes to segregate in the liquid-vapor interface of a dilute ternary alloy influences the composition and structure of that interface. The system studied has small amounts of Pb and In dissolved in Ga; it differs from a previous study of dilute alloys containing small amounts of Pb and Sn dissolved in Ga by the addition of a new variable, namely, the valence difference between the solute atoms Pb and In. This valence difference influences the electron density distribution in the alloy liquid-vapor interface in proportion to the excess concentrations of the solute species in the interface, and thereby should affect the structure of the interface. We find that for a ternary PbInGa alloy that contains 0.039 at. % Pb and 6.31 at. % In, the Pb that segregates in the liquid-vapor interface forms a two-dimensional hexagonal crystal phase that undergoes a first-order transition to a disordered phase at T=29.0±0.1 deg. C. The two-dimensional crystalline Pb forms about 0.6 of a full monolayer; the remainder of the outer stratum of the liquid-vapor interface is filled with two-dimensional liquid In. For a ternary PbInGa alloy that contains the same amount of Pb and 12.2 at. % In, the Pb that segregates in the liquid-vapor interface forms a two-dimensional liquid down to 26.0 deg. C, the lowest temperature at which data were taken. For temperatures in excess of 29.0 deg. C two-dimensional liquid Pb and two-dimensional liquid In coexist in the interface, with the fractional occupation of the monolayer by In exceeding the fractional occupation by Pb

Interface electron structure of Fe3Al/TiC composites

Institute of Scientific and Technical Information of China (English)

PANG Lai-xue; SUN Kang-ning; SUN Jia-tao; FAN Run-hua; REN Shuai

2006-01-01

Based on YU's solids and molecules emperical electron theory(EET), interface valence electron structure of TiC-Fe3Al composites was set up, and the valence electron density of different atomic states TiC and Fe3Al composites in various planes was determined. The results indicate that the electron density of (100)Fe3Al is consistent with that of (110)TiC in the first-class approximation, the absolute value of minimum electron density difference along the interface is 0.007 37 nm-2, and the relative value is 0.759%. (110)TiC//(100)Fe3Al preferred orientation is believed to benefit the formation of the cuboidal shape TiC. In the other hand, it shows that the particle growth is accompanied by the transport of electron, the deviation continuity of electron density intrinsically hinders the grain growth. The electron density of (100)TiC is not consistent with Fe3Al arbitrary crystallographic plane,thus it well explains that the increased titanium and carbon contents do not increase the size of large particles. The crystallographic orientation of (110)TiC//(100)FeAl will improve the mechanical properties. Therefore interface electron theory is an effective theoretical implement for designing excellent property of composites.

Environmental materials and interfaces

International Nuclear Information System (INIS)

1991-11-01

A workshop that explored materials and interfaces research needs relevant to national environmental concerns was conducted at Pacific Northwest Laboratory. The purposes of the workshop were to refine the scientific research directions being planned for the Materials and Interface Program in the Molecular Science Research Center (MSRC) and further define the research and user equipment to the included as part of the proposed Environmental and Molecular Science Laboratory (EMSL). Three plenary information sessions served to outline the background, objectives, and status of the MSRC and EMSL initiatives; selected specific areas with environmentally related materials; and the status of capabilities and facilities planned for the EMSL. Attention was directed to four areas where materials and interface science can have a significant impact on prevention and remediation of environmental problems: in situ detection and characterization of hazardous wastes (sensors), minimization of hazardous waste (separation membranes, ion exchange materials, catalysts), waste containment (encapsulation and barrier materials), and fundamental understanding of contaminant transport mechanisms. During all other sessions, the participants were divided into three working groups for detailed discussion and the preparation of a written report. The working groups focused on the areas of interface structure and chemistry, materials and interface stability, and materials synthesis. These recommendations and suggestions for needed research will be useful for other researchers in proposing projects and for suggesting collaborative work with MSRC researchers. 1 fig

Effects of graphene defect on electronic structures of its interface with organic semiconductor

Energy Technology Data Exchange (ETDEWEB)

Yang, Qing-Dan; Wang, Chundong; Mo, Hin-Wai; Lo, Ming-Fai; Yuen, Muk Fung; Ng, Tsz-Wai, E-mail: tszwaing@cityu.edu.hk, E-mail: apcslee@cityu.edu.hk; Zhang, Wen-Jun; Lee, Chun-Sing, E-mail: tszwaing@cityu.edu.hk, E-mail: apcslee@cityu.edu.hk [Department of Physics and Materials Science, Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong (Hong Kong); Dou, Wei-Dong [Department of Physics and Materials Science, Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong (Hong Kong); Physics Department, Shaoxing University, Shaoxing 312000 (China); Tsang, Sai-Wing [Department of Physics and Materials Science, City University of Hong Kong (Hong Kong)

2015-03-30

Electronic structures of copper hexadecafluorophthalocyanine (F{sub 16}CuPc)/graphene with different defect density were studied with ultra-violet photoelectron spectroscopy. We showed that the charge transfer interaction and charge flow direction can be interestingly tuned by controlling the defect density of graphene through time-controlled H{sub 2} plasma treatment. By increasing the treatment time of H{sub 2} plasma from 30 s to 5 min, both the interface surface dipole and the electron transporting barrier at F{sub 16}CuPc/graphene interface are significantly reduced from 0.86 to 0.56 eV and 0.71 to 0.29 eV, respectively. These results suggested that graphene's defect control is a simple approach for tuning electronic properties of organic/graphene interfaces.

Interfacial bonding and electronic structure of GaN/GaAs interface: A first-principles study

International Nuclear Information System (INIS)

Cao, Ruyue; Zhang, Zhaofu; Wang, Changhong; Li, Haobo; Dong, Hong; Liu, Hui; Wang, Weichao; Xie, Xinjian

2015-01-01

Understanding of GaN interfacing with GaAs is crucial for GaN to be an effective interfacial layer between high-k oxides and III-V materials with the application in high-mobility metal-oxide-semiconductor field effect transistor (MOSFET) devices. Utilizing first principles calculations, here, we investigate the structural and electronic properties of the GaN/GaAs interface with respect to the interfacial nitrogen contents. The decrease of interfacial N contents leads to more Ga dangling bonds and As-As dimers. At the N-rich limit, the interface with N concentration of 87.5% shows the most stability. Furthermore, a strong band offsets dependence on the interfacial N concentration is also observed. The valance band offset of N7 with hybrid functional calculation is 0.51 eV. The electronic structure analysis shows that significant interface states exist in all the GaN/GaAs models with various N contents, which originate from the interfacial dangling bonds and some unsaturated Ga and N atoms. These large amounts of gap states result in Fermi level pinning and essentially degrade the device performance

Theoretical research on the propagation of the crack normal to and dwelling on the interface of the cermet cladding material structure

International Nuclear Information System (INIS)

Junru, Yang; Chuanjuan, Song; Minglan, Wang; Yeukan, Zhang; Jing, Sun

2016-01-01

The interface crack propagation problem in the cermet cladding material structure was studied. A comparative propagation property parameter (CP) suitable to judge the propagation direction of the interface crack in the cermet cladding material structure was proposed. The interface crack propagation criterion was established. Theoretical models of the CPs for the crack normal to and dwelling on the interface deflecting separately into the clad, the interface and the substrate were built, and the relations between the CPs and the load action angle, the clad thickness ratio and the load were investigated with an example. The research results show that, under the research conditions, the interface crack will more easily propagate into the clad layer than into the substrate

Theoretical research on the propagation of the crack normal to and dwelling on the interface of the cermet cladding material structure

Energy Technology Data Exchange (ETDEWEB)

Junru, Yang; Chuanjuan, Song; Minglan, Wang; Yeukan, Zhang; Jing, Sun [College of Mechanical and Electronic Engineering, Shandong University of Science and Technology, Qingdao (China)

2016-01-15

The interface crack propagation problem in the cermet cladding material structure was studied. A comparative propagation property parameter (CP) suitable to judge the propagation direction of the interface crack in the cermet cladding material structure was proposed. The interface crack propagation criterion was established. Theoretical models of the CPs for the crack normal to and dwelling on the interface deflecting separately into the clad, the interface and the substrate were built, and the relations between the CPs and the load action angle, the clad thickness ratio and the load were investigated with an example. The research results show that, under the research conditions, the interface crack will more easily propagate into the clad layer than into the substrate.

Evolution of dispersion fuel meat structure caused by interface reaction

International Nuclear Information System (INIS)

Xing Zhonghu; Ying Shihao

2000-01-01

In reactor operation, the resultant layers are formed by interdiffusion at the fuel particle-matrix interfaces of U 3 Si 2 -Al dispersion fuel. This results in the evolution of meat structure. On the basis of Monte-Carlo method, the author developed simulation method of fuel meat, and simulated the stochastic space locations of spherical fuel particles in the meat. The fuel volume fraction is 43%, and the particles are in definite size distribution. For the 13551 simulated particle samples, the evolution of meat structure is calculated with layer thickness ranging from 0 to 16 μm. The parameters of meat structure include the U 3 Si 2 fuel volume fraction, resultant layer volume fraction, Al matrix volume fraction, particle contact probability and overlap degree as functions of layer thickness

Engineering the Surface/Interface Structures of Titanium Dioxide Micro and Nano Architectures towards Environmental and Electrochemical Applications

DEFF Research Database (Denmark)

Wang, Xiaoliang; Zhao, Yanyan; Mølhave, Kristian

2017-01-01

advances in the surface and interface engineering and applications in environmental and electrochemical applications. We analyze the advantages of surface/interface engineered TiO₂ micro and nano structures, and present the principles and growth mechanisms of TiO₂ nanostructures via different strategies...

Atomic structure and orientation relations of interfaces between Ag and ZnO

NARCIS (Netherlands)

Vellinga, W.P.; Hosson, de J.Th.M.

1997-01-01

This paper presents the results of investigations of Ag-ZnO interfaces, produced by internal oxidation of an Ag-Zn alloy. ZnO precipitates with the wurtzite structure were found exhibiting mainly one orientation relation with the Ag matrix. However, closely related ORs were found, rotated by small

Interface structure and composition of MoO3/GaAs(0 0 1)

Science.gov (United States)

Sarkar, Anirban; Ashraf, Tanveer; Grafeneder, Wolfgang; Koch, Reinhold

2018-04-01

We studied growth, structure, stress, oxidation state as well as surface and interface structure and composition of thermally-evaporated thin MoO3 films on the technologically important III/V-semiconductor substrate GaAs(0 0 1). The MoO3 films grow with Mo in the 6+  oxidation state. The electrical resistance is tunable by the oxygen partial pressure during deposition from transparent insulating to semi-transparant halfmetallic. In the investigated growth temperature range (room temperature to 200 °C) no diffraction spots are detected by x-ray diffraction. However, high resolution transmission electron microscopy reveals the formation of MoO3 nanocrystal grains with diameters of 5–8 nm. At the interface a  ≈3 nm-thick intermediate layer has formed, where the single-crystal lattice of GaAs gradually transforms to the nanocrystalline MoO3 structure. This interpretation is corroborated by our in situ and real-time stress measurements evidencing a two-stage growth process as well as by elemental interface analysis revealing coexistance of Ga, As, Mo, and oxygen in a intermediate layer of 3–4 nm.

Communication: Probing the absolute configuration of chiral molecules at aqueous interfaces

Energy Technology Data Exchange (ETDEWEB)

Lotze, Stephan, E-mail: lotze@amolf.nl; Versluis, Jan [FOM Institute for Atomic and Molecular Physics, Science Park 104, 1098 XG Amsterdam (Netherlands); Olijve, Luuk L. C.; Schijndel, Luuk van; Milroy, Lech G.; Voets, Ilja K. [Laboratory of Macromolecular and Organic Chemistry, Department of Chemical Engineering and Chemistry, and Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Bakker, Huib J., E-mail: bakker@amolf.nl [FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam (Netherlands)

2015-11-28

We demonstrate that the enantiomers of chiral macromolecules at an aqueous interface can be distinguished with monolayer sensitivity using heterodyne-detected vibrational sum-frequency generation (VSFG). We perform VSFG spectroscopy with a polarization combination that selectively probes chiral molecular structures. By using frequencies far detuned from electronic resonances, we probe the chiral macromolecular structures with high surface specificity. The phase of the sum-frequency light generated by the chiral molecules is determined using heterodyne detection. With this approach, we can distinguish right-handed and left-handed helical peptides at a water-air interface. We thus show that heterodyne-detected VSFG is sensitive to the absolute configuration of complex, interfacial macromolecules and has the potential to determine the absolute configuration of enantiomers at interfaces.

Configurations of NPD : production interfaces and interface integration mechanisms

NARCIS (Netherlands)

Smulders, F.E.H.M.; Boer, H.; Hansen, P.H.K.; Gubi, E.; Dorst, C.H.

2002-01-01

This paper describes and illustrates different configurations of the interface between new product development and production processes, including both intra–firm and inter–firm interfaces. These configurations are partly based on a process view of product innovation and partly on a structural view

Interface formation and defect structures in epitaxial La2Zr2O7 thin films on (111) Si

International Nuclear Information System (INIS)

Seo, J.W.; Fompeyrine, J.; Guiller, A.; Norga, G.; Marchiori, C.; Siegwart, H.; Locquet, J.-P.

2003-01-01

We have studied the growth of epitaxial La 2 Zr 2 O 7 thin films on (111) Si. Although the interface structure can be strongly affected by the Si oxidation during the deposition process, epitaxial growth of La 2 Zr 2 O 7 was obtained. A detailed study by means of transmission electron microscopy reveals two types of structures (pyrochlore and fluorite) with the same average chemical composition but strong differences in reactivity and interface formation. The structural complexity of the ordered pyrochlore structure seems to prevent excess oxygen diffusion and interfacial SiO 2 formation

Effect of the change in the interface structure of Pd(100)/SrTiO{sub 3} for quantum-well induced ferromagnetism

Energy Technology Data Exchange (ETDEWEB)

Sakuragi, Shunsuke, E-mail: sakuragi@az.appi.keio.ac.jp [Department of Applied Physics and Physico-Informatics, Faculty of Science and Technology, Keio University, Hiyoshi, Yokohama 223-0061 (Japan); Ogawa, Tomoyuki [Department of Electronic Engineering, Graduate School of Engineering, Tohoku University, Aza-Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Sato, Tetsuya [Department of Applied Physics and Physico-Informatics, Faculty of Science and Technology, Keio University, Hiyoshi, Yokohama 223-0061 (Japan)

2017-02-01

Measurements of temperature dependent magnetization of Pd(100) ultrathin films on SrTiO{sub 3}(100) substrates which shows quantum-well induced ferromagnetism were performed. We observed the jump in magnetization of Pd(100) due to the structural phase transition of SrTiO{sub 3}, and then, the disappearance of ferromagnetism after temperature-cycle repetition. X-ray reflectivity measurement revealed that the density of a few layers in the Pd film decreased near the Pd/SrTiO{sub 3} interface after temperature cycles. This suggests that the structural change affects the quantum-well induced ferromagnetism, and lowering of the crystallinity of Pd at the interface has a negative effect on quantum-well induced ferromagnetism of Pd(100) ultrathin films. - Highlights: • Interface manipulation of quantum-well induced ferromagnetism was performed. • Ferromagnetic Pd(100) ultrathin films on SrTiO{sub 3} substrate were prepared. • The structural phase transition of SrTiO{sub 3} degraded gradually the interface structure. • Change in the interface structure caused change in the magnetic moment of Pd. • Magnetic change was interpreted by modulation in the effective thickness of the film.

Allocating fuel breaks to optimally protect structures in the wildland-urban interface

Science.gov (United States)

Avi Bar-Massada; Volker C. Radeloff; Susan I. Stewart

2011-01-01

Wildland fire is a major concern in the wildland-urban interface (WUI), where human structures intermingle with wildland vegetation. Reducing wildfire risk in the WUI is more complicated than in wildland areas, owing to interactions between spatial patterns of housing and wildland fuels. Fuel treatments are commonly applied in wildlands surrounding WUI communities....

A Machine Learning Approach for Hot-Spot Detection at Protein-Protein Interfaces

Directory of Open Access Journals (Sweden)

Rita Melo

2016-07-01

Full Text Available Understanding protein-protein interactions is a key challenge in biochemistry. In this work, we describe a more accurate methodology to predict Hot-Spots (HS in protein-protein interfaces from their native complex structure compared to previous published Machine Learning (ML techniques. Our model is trained on a large number of complexes and on a significantly larger number of different structural- and evolutionary sequence-based features. In particular, we added interface size, type of interaction between residues at the interface of the complex, number of different types of residues at the interface and the Position-Specific Scoring Matrix (PSSM, for a total of 79 features. We used twenty-seven algorithms from a simple linear-based function to support-vector machine models with different cost functions. The best model was achieved by the use of the conditional inference random forest (c-forest algorithm with a dataset pre-processed by the normalization of features and with up-sampling of the minor class. The method has an overall accuracy of 0.80, an F1-score of 0.73, a sensitivity of 0.76 and a specificity of 0.82 for the independent test set.

Database structures and interfaces for W7-X

International Nuclear Information System (INIS)

Heimann, P.; Bluhm, T.; Hennig, Ch.; Kroiss, H.; Kuehner, G.; Maier, J.; Riemann, H.; Zilker, M.

2008-01-01

The W7-X experiment of the IPP, under construction in Greifswald Germany, is designed to operate in a quasi-steady-state scenario. The database structures and interfaces used for discharge description and execution have to reflect this continuous mode of operation. In close collaboration between the control group of W7-X and the data acquisition group a combined design of the data structures used for describing the configuration and the operation of the experiment was developed. To guarantee access to this information from all participating stations a TCP/IP portal and a proxy server were developed. This portal enables especially the VxWorks real-time operating systems of the control stations to access the information in the object-oriented database. The database schema includes now a more functional description of the experiment and gives the physicists a more simplified view of the necessary definitions of operational parameters. The scheduling of the long discharges of W7-X will be done by predefining operational parameters in segments and scenarios, where a scenario is a fixed sequence of segments with a common physical background. To hide the specialized information contained in the basic parameters from the experiment leader or physicist an abstraction layer was introduced that only shows physically interesting information. An executable segment will be generated after verifying the consistency of the high-level parameters by using a transformation function for every basic parameter needed. Since the database contains all configurations and discharge definitions necessary to operate the experiment, it is very important to give the user a tool to manipulate this information in an intuitive way. A special editor (ConfiX) was designed and implemented for this task. At the moment the basic functionality for dealing with all kind of objects in the database is available. Future releases will extend the functionality to defining and editing configurations, segments

Novel Music Segmentation Interface and the Jazz Tune Collection

NARCIS (Netherlands)

Rodríguez López, M.E.; Bountouridis, D.; Volk, A.

2015-01-01

In this paper we present MOSSA, an easy-to-use interface for mobile devices, developed to annotate the segment structure of music. Moreover, we present the jazz tune collection (JTC), a database of 125 Jazz melodies annotated using MOSSA, and developed specifically for benchmarking of computational

Detection and characterization of usability problems in structured data entry interfaces in dentistry

NARCIS (Netherlands)

Walji, M.F.; Kalenderian, E.; Tran, D.; Kookal, K.K.; Nguyen, V.; Tokede, O.; White, J.M.; Vaderhobli, R.; Ramoni, R.; Stark, P.C.; Kimmes, N.S.; Schoonheim-Klein, M.E.; Patel, V.L.

2013-01-01

Background Poor usability is one of the major barriers for optimally using electronic health records (EHRs). Dentists are increasingly adopting EHRs, and are using structured data entry interfaces to enter data such that the data can be easily retrieved and exchanged. Until recently, dentists have

High temperature interface superconductivity

International Nuclear Information System (INIS)

Gozar, A.; Bozovic, I.

2016-01-01

Highlight: • This review article covers the topic of high temperature interface superconductivity. • New materials and techniques used for achieving interface superconductivity are discussed. • We emphasize the role played by the differences in structure and electronic properties at the interface with respect to the bulk of the constituents. - Abstract: High-T_c superconductivity at interfaces has a history of more than a couple of decades. In this review we focus our attention on copper-oxide based heterostructures and multi-layers. We first discuss the technique, atomic layer-by-layer molecular beam epitaxy (ALL-MBE) engineering, that enabled High-T_c Interface Superconductivity (HT-IS), and the challenges associated with the realization of high quality interfaces. Then we turn our attention to the experiments which shed light on the structure and properties of interfacial layers, allowing comparison to those of single-phase films and bulk crystals. Both ‘passive’ hetero-structures as well as surface-induced effects by external gating are discussed. We conclude by comparing HT-IS in cuprates and in other classes of materials, especially Fe-based superconductors, and by examining the grand challenges currently laying ahead for the field.

The Development of Target-Specific Pose Filter Ensembles To Boost Ligand Enrichment for Structure-Based Virtual Screening.

Science.gov (United States)

Xia, Jie; Hsieh, Jui-Hua; Hu, Huabin; Wu, Song; Wang, Xiang Simon

2017-06-26

Structure-based virtual screening (SBVS) has become an indispensable technique for hit identification at the early stage of drug discovery. However, the accuracy of current scoring functions is not high enough to confer success to every target and thus remains to be improved. Previously, we had developed binary pose filters (PFs) using knowledge derived from the protein-ligand interface of a single X-ray structure of a specific target. This novel approach had been validated as an effective way to improve ligand enrichment. Continuing from it, in the present work we attempted to incorporate knowledge collected from diverse protein-ligand interfaces of multiple crystal structures of the same target to build PF ensembles (PFEs). Toward this end, we first constructed a comprehensive data set to meet the requirements of ensemble modeling and validation. This set contains 10 diverse targets, 118 well-prepared X-ray structures of protein-ligand complexes, and large benchmarking actives/decoys sets. Notably, we designed a unique workflow of two-layer classifiers based on the concept of ensemble learning and applied it to the construction of PFEs for all of the targets. Through extensive benchmarking studies, we demonstrated that (1) coupling PFE with Chemgauss4 significantly improves the early enrichment of Chemgauss4 itself and (2) PFEs show greater consistency in boosting early enrichment and larger overall enrichment than our prior PFs. In addition, we analyzed the pairwise topological similarities among cognate ligands used to construct PFEs and found that it is the higher chemical diversity of the cognate ligands that leads to the improved performance of PFEs. Taken together, the results so far prove that the incorporation of knowledge from diverse protein-ligand interfaces by ensemble modeling is able to enhance the screening competence of SBVS scoring functions.

Structures in the communication between lexicographer and programmer: Database and interface

DEFF Research Database (Denmark)

Tarp, Sven

2015-01-01

This paper deals exclusively with e-lexicography. It intends to answer the question how much a lexicographer in charge of a new e-dictionary project should know about lexicographical structures, and how this knowledge could be communicated to the IT programmer designing the underlying database...... and the corresponding user interfaces. With this purpose, it first defines the concepts of lexicographical database, e-dictionary and e-lexicographical structure. Then it discusses some of the new ways in which lexicographical structures express themselves in the digital environment. It stresses, above all......, their dynamic character and great complexity which make it extremely difficult and time-consuming for the lexicographer to get an overview of all the structures in an e-lexicographical project. Finally, and based upon the experience from the planning and design of five e-dictionaries, it shows how...

Structural and shear characteristics of adsorbed sodium caseinate and monoglyceride mixed monolayers at the air-water interface.

Science.gov (United States)

Rodríguez Patino, Juan M; Cejudo Fernández, Marta; Carrera Sánchez, Cecilio; Rodríguez Niño, Ma Rosario

2007-09-01

The structural and shear characteristics of mixed monolayers formed by an adsorbed Na-caseinate film and a spread monoglyceride (monopalmitin or monoolein) on the previously adsorbed protein film have been analyzed. Measurements of the surface pressure (pi)-area (A) isotherm and surface shear viscosity (eta(s)) were obtained at 20 degrees C and at pH 7 in a modified Wilhelmy-type film balance. The structural and shear characteristics of the mixed films depend on the surface pressure and on the composition of the mixed film. At surface pressures lower than the equilibrium surface pressure of Na-caseinate (at picaseinate and monoglyceride coexist at the interface, with a structural polymorphism or a liquid expanded structure due to the presence of monopalmitin or monoolein in the mixture, respectively. At higher surface pressures, collapsed Na-caseinate residues may be displaced from the interface by monoglyceride molecules. For a Na-caseinate-monopalmitin mixed film the eta(s) value varies greatly with the surface pressure (or surface density) of the mixed monolayer at the interface. In general, the greater the surface pressure, the greater are the values of eta(s). However, the values of eta(s) for a Na-caseinate-monoolein mixed monolayer are very low and practically do not depend on the surface pressure. The collapsed Na-caseinate residues displaced from the interface by monoglyceride molecules at pi>pi(e)(CS) have important repercussions on the shear characteristics of the mixed films.

Structure of the Buried Metal-Molecule Interface in Organic Thin Film Devices

DEFF Research Database (Denmark)

Hansen, Christian Rein; Sørensen, Thomas Just; Glyvradal, Magni

2009-01-01

By use of specular X-ray reflectivity (XR) the structure of a metal-covered organic thin film device is measured with angstrom resolution. The model system is a Langmuir-Blodgett (LB) film, sandwiched between a silicon substrate and a top electrode consisting of 25 Å titanium and 100 Å aluminum....... By comparison of XR data for the five-layer Pb2+ arachidate LB film before and after vapor deposition of the Ti/Al top electrode, a detailed account of the structural damage to the organic film at the buried metal-molecule interface is obtained. We find that the organized structure of the two topmost LB layers...

Structural and mechanical design of tissue interfaces in the giant reed Arundo donax.

Science.gov (United States)

Rüggeberg, Markus; Burgert, Ingo; Speck, Thomas

2010-03-06

The culms of the giant reed Arundo donax represent slender tube-like structures. Several nodes along the culm, a ring of sclerenchymatous fibres in the periphery of the culm wall and numerous isolated vascular bundles enclosed by fibre rings in the culm wall function as stiffening elements. The bundles are embedded in lignified parenchyma. Micromechanical analysis indicated differences in stiffness between the individual tissues of more than one order of magnitude. In case of abrupt transitions in stiffness at the interfaces, stress discontinuities arise under dynamic loads. This eventually leads to critical shear stresses at cell ends, and culm failure may be initiated at these points. Pronounced mechanical differences between individual tissues can be compromised by gradual transitions at their interfaces. Ultrastructural and spectroscopic investigations with high spatial resolution revealed a gradual transition of cell parameters (cell wall area fraction and cell length). However, cell wall parameters (cellulose microfibril angle and lignin content) showed abrupt transitions or remained almost constant across the interfaces between various tissues. The design principles found at the interfaces between tissues in the culm walls of A. donax are discussed as an adaptation strategy to mechanical loads at different levels of hierarchy.

Chemical states and electronic structure of a HfO(-2)/Ge(001) interface

International Nuclear Information System (INIS)

Seo, Kang-ill; McIntyre, Paul C.; Stanford U., Materials Sci. Dept.; Sun, Shiyu; Lee, Dong-Ick; Pianetta, Piero; SLAC, SSRL; Saraswat, Krishna C.; Stanford U., Elect. Eng. Dept.

2005-01-01

We report the chemical bonding structure and valence band alignment at the HfO 2 /Ge (001) interface by systematically probing various core level spectra as well as valence band spectra using soft x-rays at the Stanford Synchrotron Radiation Laboratory. We investigated the chemical bonding changes as a function of depth through the dielectric stack by taking a series of synchrotron photoemission spectra as we etched through the HfO 2 film using a dilute HF-solution. We found that a very non-stoichiometric GeO x layer exists at the HfO 2 /Ge interface. The valence band spectra near the Fermi level in each different film structure were carefully analyzed, and as a result, the valence band offset between Ge and GeO x was determined to be ΔE v (Ge-GeO x ) = 2.2 ± 0.15 eV, and that between Ge and HfO 2 , ΔE v (Ge-HfO 2 ) = 2.7 ± 0.15 eV

Electronic structure of the indium tin oxide/nanocrystalline anatase (TiO2)/ruthenium-dye interfaces in dye-sensitized solar cells

Science.gov (United States)

Lyon, J. E.; Rayan, M. K.; Beerbom, M. M.; Schlaf, R.

2008-10-01

The electronic structure of two interfaces commonly found in dye-sensitized photovoltaic cells based on nanocrystalline anatase TiO2 ("Grätzel cells") was investigated using photoemission spectroscopy (PES). X-ray photoemission spectroscopy (XPS) and ultraviolet photoemission spectroscopy (UPS) measurements were carried out on the indium tin oxide (ITO)/TiO2 and the TiO2/cis-bis(isothiocyanato)bis(2,2'-bipyridyl-4,4'-dicarboxylato)-ruthenium(II)bis-tetrabutylammonium dye ("N719" or "Ruthenium 535-bisTBA") interfaces. Both contacts were investigated using a multistep deposition procedure where the entire structure was prepared in vacuum using electrospray deposition. In between deposition steps the surface was characterized with XPS and UPS resulting in a series of spectra, allowing the determination of the orbital and band lineup at the interfaces. The results of these efforts confirm previous PES measurements on TiO2/dye contacts prepared under ambient conditions, suggesting that ambient contamination might not have significant influence on the electronic structure at the dye/TiO2 interface. The results also demonstrate that there may be a significant barrier for electron injection at the sputtered ITO/TiO2 interface and that this interface should be viewed as a semiconductor heterojunction rather than as metal-semiconductor (Schottky) contact.

Order in nanometer thick intergranular films at Au-sapphire interfaces

Energy Technology Data Exchange (ETDEWEB)

Baram, Mor [Department of Materials Engineering, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Garofalini, Stephen H. [Department of Materials Science and Engineering, Rutgers University, Piscataway, NJ 08854-8065 (United States); Kaplan, Wayne D., E-mail: kaplan@tx.technion.ac.il [Department of Materials Engineering, Technion-Israel Institute of Technology, Haifa 32000 (Israel)

2011-08-15

Highlights: {yields} Au particles were equilibrated on (0 0 0 1) sapphire in the presence of anorthite. {yields} 1.2 nm thick equilibrium films (complexions) were formed at the Au-sapphire interfaces. {yields} Quantitative HRTEM was used to study the atomistic structure of the films. {yields} Structural order was observed in the 1.2 nm thick films adjacent to the sapphire crystal. {yields} This demonstrates that ordering is an intrinsic part of equilibrium intergranular films. - Abstract: In recent years extensive studies on interfaces have shown that {approx}1 nm thick intergranular films (IGF) exist at interfaces in different material systems, and that IGF can significantly affect the materials' properties. However, there is great deal of uncertainty whether such films are amorphous or partially ordered. In this study specimens were prepared from Au particles that were equilibrated on sapphire substrates in the presence of anorthite glass, leading to the formation of 1.2 nm thick IGF at the Au-sapphire interfaces. Site-specific cross-section samples were characterized using quantitative high resolution transmission electron microscopy to study the atomistic structure of the films. Order was observed in the 1.2 nm thick films adjacent to the sapphire crystal in the form of 'Ca cages', experimentally demonstrating that ordering is an intrinsic part of IGF, as predicted from molecular dynamics and diffuse interface theory.

Structure and property relations of macromolecular self-assemblies at interfaces

Science.gov (United States)

Yang, Zhihao

Hydrophilic polymer chains, poly(ethylene glycol) (PEG), are attached to glass surfaces by silylation of the silanol groups on glass surfaces with the omega-(methoxyl terminated PEG) trimethoxysilanes. These tethered polymer chains resemble the self-assembled monolayers (SAMs) of PEG, which exhibit excellent biocompatibility and provide a model system for studying the interactions of proteins with polymer surfaces. The low molecular weight PEGs tend to extend, forming a brush-like monolayer, whereas the longer polymer chains tend to interpenetrate each other, forming a mushroom-like PEG monolayer at the interface. Interactions between a plasma protein, bovine serum albumin, and the PEG-SAMs are investigated in terms of protein adsorption and diffusion on the surfaces by the technique of fluorescence recovery after photobleaching (FRAP). The diffusion and aggregation behaviors of the protein on the two monolayers are found to be quite different despite the similarities in adsorption and desorption behaviors. The results are analyzed with a hypothesis of the hydrated surface dynamics. A method of covalently bonding phospholipid molecules to silica substrates followed by loading with free phospholipids is demonstrated to form well organized and stable phospholipid self-assembled monolayers. Surfaces of such SAMs structurally mimic the aqueous sides of phospholipid bilayer membranes. The dynamics of phospholipids and an adsorbed protein, lipase, in the SAMs are probed with FRAP, in terms of lateral diffusion of both phospholipids and protein molecules. The esterase activity of lipase on the SAM surfaces is confirmed by the hydrolysis reaction of a substrate, umbelliferone stearate, showing such lipid SAMs posess biomembrane functionality in terms of interfacial activation of the membranous enzymes. Dynamics of polyethylene oxide and polypropylene oxide tri-block copolymers, PEO-PPO-PEO and PPO-PEO-PPO, at the air/water interface upon thermal stimulation is studied by

Parent-martensite interface structure in ferrous systems

International Nuclear Information System (INIS)

Ma, X.; Pond, R.C.

2007-01-01

Recently, a Topological Model of martensitic transformations has been presented wherein the habit plane is a semi-coherent structure, and the transformation mechanism is shown explicitly to be diffusionless. This approach is used here to model martensitic transformations in ferrous alloys. The habit plane comprises coherent (1 1 1) γ parallel (0 1 1) α terraces where the coherency strains are accommodated by a network of dislocations, originating in the martensite phase, and disconnections (transformation dislocations). The disconnections can move conservatively across the interface, thereby effecting the transformation. Since the disconnections exhibit step character, the overall habit plane deviates from the terrace plane. A range of network geometries is predicted corresponding to orientation relationships varying from Nishiyama-Wasserman to Kurdjumov-Sachs. This range of solutions includes habit planes close to {2 9 5}, {5 7 5} and {1 2 1}, in good agreement with experimental observations in various ferrous alloys

Magnetism at the Interface of Magnetic Oxide and Nonmagnetic Semiconductor Quantum Dots.

Science.gov (United States)

Saha, Avijit; Viswanatha, Ranjani

2017-03-28

Engineering interfaces specifically in quantum dot (QD) heterostructures provide several prospects for developing multifunctional building block materials. Precise control over internal structure by chemical synthesis offers a combination of different properties in QDs and allows us to study their fundamental properties, depending on their structure. Herein, we studied the interface of magnetic/nonmagnetic Fe 3 O 4 /CdS QD heterostructures. In this work, we demonstrate the decrease in the size of the magnetic core due to annealing at high temperature by the decrease in saturation magnetization and blocking temperature. Furthermore, surprisingly, in a prominently optically active and magnetically inactive material such as CdS, we observe the presence of substantial exchange bias in spite of the nonmagnetic nature of CdS QDs. The presence of exchange bias was proven by the increase in magnetic anisotropy as well as the presence of exchange bias field (H E ) during the field-cooled magnetic measurements. This exchange coupling was eventually traced to the in situ formation of a thin antiferromagnetic FeS layer at the interface. This is verified by the study of Fe local structure using X-ray absorption fine structure spectroscopy, demonstrating the importance of interface engineering in QDs.

Engineering Musculoskeletal Tissue Interfaces

Directory of Open Access Journals (Sweden)

Ece Bayrak

2018-04-01

Full Text Available Tissue engineering aims to bring together biomaterials, cells, and signaling molecules within properly designed microenvironments in order to create viable treatment options for the lost or malfunctioning tissues. Design and production of scaffolds and cell-laden grafts that mimic the complex structural and functional features of tissues are among the most important elements of tissue engineering strategy. Although all tissues have their own complex structure, an even more complex case in terms of engineering a proper carrier material is encountered at the tissue interfaces, where two distinct tissues come together. The interfaces in the body can be examined in four categories; cartilage-bone and ligament-bone interfaces at the knee and the spine, tendon-bone interfaces at the shoulder and the feet, and muscle-tendon interface at the skeletal system. These interfaces are seen mainly at the soft-to-hard tissue transitions and they are especially susceptible to injury and tear due to the biomechanical inconsistency between these tissues where high strain fields are present. Therefore, engineering the musculoskeletal tissue interfaces remain a challenge. This review focuses on recent advancements in strategies for musculoskeletal interface engineering using different biomaterial-based platforms and surface modification techniques.

Effect of Interface Structure on Thermal Boundary Conductance by using First-principles Density Functional Perturbation Theory

Institute of Scientific and Technical Information of China (English)

GAO Xue; ZHANG Yue; SHANG Jia-Xiang

2011-01-01

We choose a Si/Ge interface as a research object to investigate the infiuence of interface disorder on thermal boundary conductance. In the calculations, the diffuse mismatch model is used to study thermal boundary conductance between two non-metallic materials, while the phonon dispersion relationship is calculated by the first-principles density functional perturbation theory. The results show that interface disorder limits thermal transport. The increase of atomic spacing at the interface results in weakly coupled interfaces and a decrease in the thermal boundary conductance. This approach shows a simplistic method to investigate the relationship between microstructure and thermal conductivity.%We choose a Si/Ge interface as a research object to investigate the influence of interface disorder on thermal boundary conductance.In the calculations,the diffuse mismatch model is used to study thermal boundary conductance between two non-metallic materials,while the phonon dispersion relationship is calculated by the first-principles density functional perturbation theory.The results show that interface disorder limits thermal transport.The increase of atomic spacing at the interface results in weakly coupled interfaces and a decrease in the thermal boundary conductance.This approach shows a simplistic method to investigate the relationship between microstructure and thermal conductivity.It is well known that interfaces can play a dominant role in the overall thermal transport characteristics of structures whose length scale is less than the phonon mean free path.When heat flows across an interface between two different materials,there exists a temperature jump at the interface.Thermal boundary conductance (TBC),which describes the efficiency of heat flow at material interfaces,plays an importance role in the transport of thermal energy in nanometerscale devices,semiconductor superlattices,thin film multilayers and nanocrystalline materials.[1

Generating User Interfaces with the FUSE-System

OpenAIRE

Frank Lonczewski; Siegfried Schreiber

2017-01-01

With the FUSE(Formal User interface Specification Environment)-System we present a methodology and a set of integrated tools for the automatic generation of graphical user interfaces. FUSE provides tool-based support for all phases (task-, user-, problem domain analysis, design of the logical user interface, design of user interface in a particular layout style) of the user interface development process. Based on a formal specification of dialogue- and layout guidelines, FUSE allows the autom...

Magnetic coupling at perovskite and rock-salt structured interfaces

Energy Technology Data Exchange (ETDEWEB)

Matvejeff, M., E-mail: mikko.matvejeff@picosun.com [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, 277-8581 Chiba (Japan); Department of Chemistry, Aalto University, Kemistintie 1, 02150 Espoo (Finland); Ahvenniemi, E. [Department of Chemistry, Aalto University, Kemistintie 1, 02150 Espoo (Finland); Takahashi, R.; Lippmaa, M. [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, 277-8581 Chiba (Japan)

2015-10-05

We study magnetic coupling between hole-doped manganite layers separated by either a perovskite or a rock-salt barrier of variable thickness. Both the type and the quality of the interface have a strong impact on the minimum critical barrier thickness where the manganite layers become magnetically decoupled. A rock-salt barrier layer only 1 unit cell (0.5 nm) thick remains insulating and is able to magnetically de-couple the electrode layers. The technique can therefore be used for developing high-performance planar oxide electronic devices such as magnetic tunnel junctions and quantum well structures that depend on magnetically and electronically sharp heterointerfaces.

Electronic structures and stability of Ni/Bi2Te3 and Co/Bi2Te3 interfaces

International Nuclear Information System (INIS)

Xiong Ka; Wang Weichao; Alshareef, Husam N; Gupta, Rahul P; Gnade, Bruce E; Cho, Kyeongjae; White, John B

2010-01-01

We investigate the electronic structures and stability for Ni/Bi 2 Te 3 , NiTe/Bi 2 Te 3 , Co/Bi 2 Te 3 and CoTe 2 /Bi 2 Te 3 interfaces by first-principles calculations. It is found that the surface termination strongly affects the band alignment. Ni and Co are found to form Ohmic contacts to Bi 2 Te 3 . The interface formation energy for Co/Bi 2 Te 3 interfaces is much lower than that of Ni/Bi 2 Te 3 interfaces. Furthermore, we found that NiTe on Bi 2 Te 3 is more stable than Ni, while the formation energies for Co and CoTe 2 on Bi 2 Te 3 are comparable.

Interface characterization of InSb MOS structures

Energy Technology Data Exchange (ETDEWEB)

Shapira, Y.; Bregman, J.; Calahorra, Z.; Goshen, R.

1982-03-26

The electrical properties of MOS devices are critically dependent on the oxide-semiconductor interface. The preparation of suitable insulating layers of oxide or other material is essential for the performance of such devices and it is particularly difficult in the case of III-V compound semiconductors. We report a method of preparing an insulating layer on InSb by a plasma oxidation process. The oxidation method will be described as well as results of the analysis of the oxide-semiconductor interface by electrical and compositional techniques. Capacitance-voltage characteristics reveal the existence of interface states which are distributed near the conduction and the valence bands with a higher density near the former. Depth profiling of the oxide by Ar/sup +/ sputtering and Auger electron spectroscopy (AES) shows that the oxide is composed of a mixture of indium oxide with antimony oxide.

WRAP module 1 DMS/PCS interface definition document

International Nuclear Information System (INIS)

Weidert, J.R.

1994-01-01

This document has been developed to define the computer software interfaces between Waste Receiving ampersand Processing Module 1 (WRAP 1) computer systems. The interfaces include those data interfaces which exist between the Plant Control System (PCS) and Data Management System (DMS), between the DMS and Non-Destructive Assay (NDA) equipment, and between the DMS and Boxed Waste Assay System (BWAS) equipment. In addition to the data interfaces between the various WRAP computer systems; there are also a number of control functions between WRAP 1 equipment. These control function interfaces have been specified in WRAP Construction specification 13462 and the associated equipment specifications. The PCS vendor has been listed in the equipment specifications as the responsible party for establishing the final control system interface between the PCS and Non-Destructive Examination (NDE) Equipment, the PCS and Non-Destructive Assay (NDA) Equipment, and the PCS and BWAS equipment. The primary interface requirements between these systems are addressed in Specification Sections 13462, 13532, 13533, 13026, 13537, and 13538. Additional requirements may be found in other specification sections such as the Automatic Stacker Retriever System (AS/RS) Technical Specification 14520 and the WRAP 1 Data Management System Software Requirements Specification

User Interface Design in Medical Distributed Web Applications.

Science.gov (United States)

Serban, Alexandru; Crisan-Vida, Mihaela; Mada, Leonard; Stoicu-Tivadar, Lacramioara

2016-01-01

User interfaces are important to facilitate easy learning and operating with an IT application especially in the medical world. An easy to use interface has to be simple and to customize the user needs and mode of operation. The technology in the background is an important tool to accomplish this. The present work aims to creating a web interface using specific technology (HTML table design combined with CSS3) to provide an optimized responsive interface for a complex web application. In the first phase, the current icMED web medical application layout is analyzed, and its structure is designed using specific tools, on source files. In the second phase, a new graphic adaptable interface to different mobile terminals is proposed, (using HTML table design (TD) and CSS3 method) that uses no source files, just lines of code for layout design, improving the interaction in terms of speed and simplicity. For a complex medical software application a new prototype layout was designed and developed using HTML tables. The method uses a CSS code with only CSS classes applied to one or multiple HTML table elements, instead of CSS styles that can be applied to just one DIV tag at once. The technique has the advantage of a simplified CSS code, and a better adaptability to different media resolutions compared to DIV-CSS style method. The presented work is a proof that adaptive web interfaces can be developed just using and combining different types of design methods and technologies, using HTML table design, resulting in a simpler to learn and use interface, suitable for healthcare services.

Atomistic Simulation of Interfaces in Materials of Solid State Ionics

Science.gov (United States)

Ivanov-Schitz, A. K.; Mazo, G. N.

2018-01-01

The possibilities of describing correctly interfaces of different types in solids within a computer experiment using molecular statics simulation, molecular dynamics simulation, and quantum chemical calculations are discussed. Heterophase boundaries of various types, including grain boundaries and solid electrolyte‒solid electrolyte and ionic conductor‒electrode material interfaces, are considered. Specific microstructural features and mechanisms of the ion transport in real heterophase structures (cationic conductor‒metal anode and anionic conductor‒cathode) existing in solid state ionics devices (such as solid-state batteries and fuel cells) are discussed.

Universal computer interfaces

CERN Document Server

Dheere, RFBM

1988-01-01

Presents a survey of the latest developments in the field of the universal computer interface, resulting from a study of the world patent literature. Illustrating the state of the art today, the book ranges from basic interface structure, through parameters and common characteristics, to the most important industrial bus realizations. Recent technical enhancements are also included, with special emphasis devoted to the universal interface adapter circuit. Comprehensively indexed.

The CAD-score web server: contact area-based comparison of structures and interfaces of proteins, nucleic acids and their complexes.

Science.gov (United States)

Olechnovič, Kliment; Venclovas, Ceslovas

2014-07-01

The Contact Area Difference score (CAD-score) web server provides a universal framework to compute and analyze discrepancies between different 3D structures of the same biological macromolecule or complex. The server accepts both single-subunit and multi-subunit structures and can handle all the major types of macromolecules (proteins, RNA, DNA and their complexes). It can perform numerical comparison of both structures and interfaces. In addition to entire structures and interfaces, the server can assess user-defined subsets. The CAD-score server performs both global and local numerical evaluations of structural differences between structures or interfaces. The results can be explored interactively using sortable tables of global scores, profiles of local errors, superimposed contact maps and 3D structure visualization. The web server could be used for tasks such as comparison of models with the native (reference) structure, comparison of X-ray structures of the same macromolecule obtained in different states (e.g. with and without a bound ligand), analysis of nuclear magnetic resonance (NMR) structural ensemble or structures obtained in the course of molecular dynamics simulation. The web server is freely accessible at: http://www.ibt.lt/bioinformatics/cad-score. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

A structured and systematic model-based development method for automotive systems, considering the OEM/supplier interface

International Nuclear Information System (INIS)

Beckers, Kristian; Côté, Isabelle; Frese, Thomas; Hatebur, Denis; Heisel, Maritta

2017-01-01

The released ISO 26262 standard for automotive systems requires to create a hazard analysis and risk assessment and to create safety goals, to break down these safety goals into functional safety requirements in the functional safety concept, to specify technical safety requirements in the safety requirements specification, and to perform several validation and verification activities. Experience shows that the definition of technical safety requirements and the planning and execution of validation and verification activities has to be done jointly by OEMs and suppliers. In this paper, we present a structured and model-based safety development approach for automotive systems. The different steps are based on Jackson's requirement engineering. The elements are represented by UML notation extended with stereotypes. The UML model enables a rigorous validation of several constraints. We make use of the results of previously published work to be able to focus on the OEM/supplier interface. We illustrate our method using a three-wheeled-tilting control system (3WTC) as running example and case study. - Highlights: • Break down functional safety requirements into technical safety requirements. • Perform a hardware metric breakdown. • Ensure completeness of the requirements by using tables with predefined cells. • Define the interface to the suppliers and address functional safety.

High Performance Computing - Power Application Programming Interface Specification Version 2.0.

Energy Technology Data Exchange (ETDEWEB)

Laros, James H. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Grant, Ryan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Levenhagen, Michael J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Olivier, Stephen Lecler [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Pedretti, Kevin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ward, H. Lee [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Younge, Andrew J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-03-01

Measuring and controlling the power and energy consumption of high performance computing systems by various components in the software stack is an active research area. Implementations in lower level software layers are beginning to emerge in some production systems, which is very welcome. To be most effective, a portable interface to measurement and control features would significantly facilitate participation by all levels of the software stack. We present a proposal for a standard power Application Programming Interface (API) that endeavors to cover the entire software space, from generic hardware interfaces to the input from the computer facility manager.

Dye-sensitized solar cells: Atomic scale investigation of interface structure and dynamics

International Nuclear Information System (INIS)

Ma Wei; Zhang Fan; Meng Sheng

2014-01-01

Recent progress in dye-sensitized solar cells (DSC) research is reviewed, focusing on atomic-scale investigations of the interface electronic structures and dynamical processes, including the structure of dye adsorption onto TiO 2 , ultrafast electron injection, hot-electron injection, multiple-exciton generation, and electron—hole recombination. Advanced experimental techniques and theoretical approaches are briefly summarized, and then progressive achievements in photovoltaic device optimization based on insights from atomic scale investigations are introduced. Finally, some challenges and opportunities for further improvement of dye solar cells are presented. (invited review — international conference on nanoscience and technology, china 2013)

Radiations at the physics-biology interface. Utilization of radiations for research

International Nuclear Information System (INIS)

Douzou, P.

1997-01-01

Structural biology, which study the relation between the structure of biomolecules and their function, is at the interface between physics and biology. With the help of large radiation instruments such as X ray diffraction and neutron scattering, important advancements have been accomplished in the understanding of specific biological functions and led to the development of protein engineering (such as directed mutagenesis)

Structural and mechanistic investigations on Salmonella typhimurium acetate kinase (AckA: identification of a putative ligand binding pocket at the dimeric interface

Directory of Open Access Journals (Sweden)

Chittori Sagar

2012-10-01

Full Text Available Abstract Background Bacteria such as Escherichia coli and Salmonella typhimurium can utilize acetate as the sole source of carbon and energy. Acetate kinase (AckA and phosphotransacetylase (Pta, key enzymes of acetate utilization pathway, regulate flux of metabolites in glycolysis, gluconeogenesis, TCA cycle, glyoxylate bypass and fatty acid metabolism. Results Here we report kinetic characterization of S. typhimurium AckA (StAckA and structures of its unliganded (Form-I, 2.70 Å resolution and citrate-bound (Form-II, 1.90 Å resolution forms. The enzyme showed broad substrate specificity with kcat/Km in the order of acetate > propionate > formate. Further, the Km for acetyl-phosphate was significantly lower than for acetate and the enzyme could catalyze the reverse reaction (i.e. ATP synthesis more efficiently. ATP and Mg2+ could be substituted by other nucleoside 5′-triphosphates (GTP, UTP and CTP and divalent cations (Mn2+ and Co2+, respectively. Form-I StAckA represents the first structural report of an unliganded AckA. StAckA protomer consists of two domains with characteristic βββαβαβα topology of ASKHA superfamily of proteins. These domains adopt an intermediate conformation compared to that of open and closed forms of ligand-bound Methanosarcina thermophila AckA (MtAckA. Spectroscopic and structural analyses of StAckA further suggested occurrence of inter-domain motion upon ligand-binding. Unexpectedly, Form-II StAckA structure showed a drastic change in the conformation of residues 230–300 compared to that of Form-I. Further investigation revealed electron density corresponding to a citrate molecule in a pocket located at the dimeric interface of Form-II StAckA. Interestingly, a similar dimeric interface pocket lined with largely conserved residues could be identified in Form-I StAckA as well as in other enzymes homologous to AckA suggesting that ligand binding at this pocket may influence the function of these

Nanoparticle Assemblies at Fluid Interfaces

Energy Technology Data Exchange (ETDEWEB)

Russell, Thomas P. [Univ. of Massachusetts, Amherst, MA (United States). Dept. of Polymer Science and Engineering

2015-03-10

A systematic study of the structure and dynamics of nanoparticles (NP) and NP-surfactants was performed. The ligands attached to both the NPs and NP-surfactants dictate the manner in which the nanoscopic materials assemble at fluid interfaces. Studies have shown that a single layer of the nanoscpic materials form at the interface to reduce the interactions between the two immiscible fluids. The shape of the NP is, also, important, where for spherical particles, a disordered, liquid-like monolayer forms, and, for nanorods, ordered domains at the interface is found and, if the monolayers are compressed, the orientation of the nanorods with respect to the interface can change. By associating end-functionalized polymers to the NPs assembled at the interface, NP-surfactants are formed that increase the energetic gain in segregating each NP at the interface which allows the NP-surfactants to jam at the interface when compressed. This has opened the possibility of structuring the two liquids by freezing in shape changes of the liquids.

Crystal structures of the human G3BP1 NTF2-like domain visualize FxFG Nup Repeat Specificity

DEFF Research Database (Denmark)

Vognsen, Tina Reinholdt; Möller, Ingvar Rúnar; Kristensen, Ole

2013-01-01

Ras GTPase Activating Protein SH3 Domain Binding Protein (G3BP) is a potential anti-cancer drug target implicated in several cellular functions. We have used protein crystallography to solve crystal structures of the human G3BP1 NTF2-like domain both alone and in complex with an FxFG Nup repeat...... peptide. Despite high structural similarity, the FxFG binding site is located between two alpha helices in the G3BP1 NTF2-like domain and not at the dimer interface as observed for nuclear transport factor 2. ITC studies showed specificity towards the FxFG motif but not FG and GLFG motifs. The unliganded...

Air–water interface of submerged superhydrophobic surfaces imaged by atomic force microscopy

Directory of Open Access Journals (Sweden)

Markus Moosmann

2017-08-01

Full Text Available Underwater air retention of superhydrophobic hierarchically structured surfaces is of increasing interest for technical applications. Persistent air layers (the Salvinia effect are known from biological species, for example, the floating fern Salvinia or the backswimmer Notonecta. The use of this concept opens up new possibilities for biomimetic technical applications in the fields of drag reduction, antifouling, anticorrosion and under water sensing. Current knowledge regarding the shape of the air–water interface is insufficient, although it plays a crucial role with regards to stability in terms of diffusion and dynamic conditions. Optical methods for imaging the interface have been limited to the micrometer regime. In this work, we utilized a nondynamic and nondestructive atomic force microscopy (AFM method to image the interface of submerged superhydrophobic structures with nanometer resolution. Up to now, only the interfaces of nanobubbles (acting almost like solids have been characterized by AFM at these dimensions. In this study, we show for the first time that it is possible to image the air–water interface of submerged hierarchically structured (micro-pillars surfaces by AFM in contact mode. By scanning with zero resulting force applied, we were able to determine the shape of the interface and thereby the depth of the water penetrating into the underlying structures. This approach is complemented by a second method: the interface was scanned with different applied force loads and the height for zero force was determined by linear regression. These methods open new possibilities for the investigation of air-retaining surfaces, specifically in terms of measuring contact area and in comparing different coatings, and thus will lead to the development of new applications.

Self-Assembly of Peptides at the Air/Water Interface

Science.gov (United States)

Sayar, Mehmet

2013-03-01

Peptides are commonly used as building blocks for design and development of novel materials with a variety of application areas ranging from drug design to biotechnology. The precise control of molecular architecture and specific nature of the nonbonded interactions among peptides enable aggregates with well defined structural and functional properties. The interaction of peptides with interfaces leads to dramatic changes in their conformational and aggregation behavior. In this talk, I will discuss our research on the interplay of intermolecular forces and influence of interfaces. In the first part the amphiphilic nature of short peptide oligomers and their behavior at the air/water interface will be discussed. The surface driving force and its decomposition will be analyzed. In the second part aggregation of peptides in bulk water and at an interface will be discussed. Different design features which can be tuned to control aggregation behavior will be analyzed.

Modeling of interface roughness in thermoelectric composite materials

International Nuclear Information System (INIS)

Gather, F; Heiliger, C; Klar, P J

2011-01-01

We use a network model to calculate the influence of the mesoscopic interface structure on the thermoelectric properties of superlattice structures consisting of alternating layers of materials A and B. The thermoelectric figure of merit of such a composite material depends on the layer thickness, if interface resistances are accounted for, and can be increased by proper interface design. In general, interface roughness reduces the figure of merit, again compared to the case of ideal interfaces. However, the strength of this reduction depends strongly on the type of interface roughness. Smooth atomic surface diffusion leading to alloying of materials A and B causes the largest reduction of the figure of merit. Consequently, in real structures, it is important not only to minimize interface roughness, but also to control the type of roughness. Although the microscopic effects of interfaces are only empirically accounted for, using a network model can yield useful information about the dependence of the macroscopic transport coefficients on the mesoscopic disorder in structured thermoelectric materials.

Electronic structures and stability of Ni/Bi2Te3 and Co/Bi2Te3 interfaces

KAUST Repository

Xiong, Ka; Wang, Weichao; Alshareef, Husam N.; Gupta, Rahul P.; White, John B.; Gnade, Bruce E.; Cho, Kyeongjae

2010-01-01

We investigate the electronic structures and stability for Ni/Bi 2Te3, NiTe/Bi2Te3, Co/Bi 2Te3 and CoTe2/Bi2Te3 interfaces by first-principles calculations. It is found that the surface termination strongly affects the band alignment. Ni and Co are found to form Ohmic contacts to Bi2Te3. The interface formation energy for Co/Bi2Te3 interfaces is much lower than that of Ni/Bi2Te3 interfaces. Furthermore, we found that NiTe on Bi2Te3 is more stable than Ni, while the formation energies for Co and CoTe2 on Bi2Te3 are comparable. © 2010 IOP Publishing Ltd.

Electronic structures and stability of Ni/Bi2Te3 and Co/Bi2Te3 interfaces

KAUST Repository

Xiong, Ka

2010-03-04

We investigate the electronic structures and stability for Ni/Bi 2Te3, NiTe/Bi2Te3, Co/Bi 2Te3 and CoTe2/Bi2Te3 interfaces by first-principles calculations. It is found that the surface termination strongly affects the band alignment. Ni and Co are found to form Ohmic contacts to Bi2Te3. The interface formation energy for Co/Bi2Te3 interfaces is much lower than that of Ni/Bi2Te3 interfaces. Furthermore, we found that NiTe on Bi2Te3 is more stable than Ni, while the formation energies for Co and CoTe2 on Bi2Te3 are comparable. © 2010 IOP Publishing Ltd.

A nonlinear interface model applied to masonry structures

Science.gov (United States)

Lebon, Frédéric; Raffa, Maria Letizia; Rizzoni, Raffaella

2015-12-01

In this paper, a new imperfect interface model is presented. The model includes finite strains, micro-cracks and smooth roughness. The model is consistently derived by coupling a homogenization approach for micro-cracked media and arguments of asymptotic analysis. The model is applied to brick/mortar interfaces. Numerical results are presented.

Crystal Structure and Substrate Specificity of PTPN12

Directory of Open Access Journals (Sweden)

Hui Li

2016-05-01

Full Text Available PTPN12 is an important tumor suppressor that plays critical roles in various physiological processes. However, the molecular basis underlying the substrate specificity of PTPN12 remains uncertain. Here, enzymological and crystallographic studies have enabled us to identify two distinct structural features that are crucial determinants of PTPN12 substrate specificity: the pY+1 site binding pocket and specific basic charged residues along its surface loops. Key structurally plastic regions and specific residues in PTPN12 enabled recognition of different HER2 phosphorylation sites and regulated specific PTPN12 functions. In addition, the structure of PTPN12 revealed a CDK2 phosphorylation site in a specific PTPN12 loop. Taken together, our results not only provide the working mechanisms of PTPN12 for desphosphorylation of its substrates but will also help in designing specific inhibitors of PTPN12.

Functional structural motifs for protein-ligand, protein-protein, and protein-nucleic acid interactions and their connection to supersecondary structures.

Science.gov (United States)

Kinjo, Akira R; Nakamura, Haruki

2013-01-01

Protein functions are mediated by interactions between proteins and other molecules. One useful approach to analyze protein functions is to compare and classify the structures of interaction interfaces of proteins. Here, we describe the procedures for compiling a database of interface structures and efficiently comparing the interface structures. To do so requires a good understanding of the data structures of the Protein Data Bank (PDB). Therefore, we also provide a detailed account of the PDB exchange dictionary necessary for extracting data that are relevant for analyzing interaction interfaces and secondary structures. We identify recurring structural motifs by classifying similar interface structures, and we define a coarse-grained representation of supersecondary structures (SSS) which represents a sequence of two or three secondary structure elements including their relative orientations as a string of four to seven letters. By examining the correspondence between structural motifs and SSS strings, we show that no SSS string has particularly high propensity to be found interaction interfaces in general, indicating any SSS can be used as a binding interface. When individual structural motifs are examined, there are some SSS strings that have high propensity for particular groups of structural motifs. In addition, it is shown that while the SSS strings found in particular structural motifs for nonpolymer and protein interfaces are as abundant as in other structural motifs that belong to the same subunit, structural motifs for nucleic acid interfaces exhibit somewhat stronger preference for SSS strings. In regard to protein folds, many motif-specific SSS strings were found across many folds, suggesting that SSS may be a useful description to investigate the universality of ligand binding modes.

Comparison of interface structure of BCC metallic (Fe, V and Nb) films on MgO (100) substrate

Energy Technology Data Exchange (ETDEWEB)

Du, J.L. [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China); Zhang, L.Y. [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an, 710049 (China); Fu, E.G., E-mail: efu@pku.edu.cn [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China); Ding, X., E-mail: dingxd@mail.xjtu.edu.cn [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an, 710049 (China); Yu, K.Y., E-mail: kyyu@cup.edu.cn [Department of Materials Science and Engineering, China University of Petroleum, Beijing 102249 (China); Wang, Y.G. [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China); Wang, Y.Q.; Baldwin, J.K. [Experimental Physical Sciences Directorate, Los Alamos National Laboratory, Los Alamos, NM 87544 (United States); Wang, X.J. [State Key Laboratory of Advanced Optical Communication Systems and Networks, Peking University, Beijing 100871 (China); Xu, P. [Department of Chemistry, Harbin Institute of Technology, Harbin, Heilongjiang, 150001 (China)

2017-07-15

Highlights: • The difference of BCC metal/MgO(100) interface configuration with various lattice mismatches is identified by experiments and simulations in terms of dislocations and work of separation. • The strength of bonds along interface is found to be the fundamental factor to determine the interface configurations between BCC metal and MgO substrate. • The combination of experiments and simulations shows that the O-atop model is the actual match type between BCC metal and MgO substrate. - Abstract: This study systematically investigates the interface structure of three body-centered-cubic (BCC) metallic (Fe, V and Nb) films grown on MgO(100) substrates through experiments and simulations. Orientation relationships of their interfaces with the different lattice mismatches exhibit cube-on-cube configurations. The misfit dislocations at these three interfaces exhibit different characteristics. High resolution TEM (HRTEM), combined with first principle calculations, demonstrates the O-atop match type between metal atoms and MgO substrates for the first time. The fundamental mechanism in determining the interface configuration is discussed in terms of the work of separation and delocalization of atomic charge density.

Molecular characterization of composite interfaces

International Nuclear Information System (INIS)

Ishida, H.

1982-01-01

The Fourier Transform Infrared Spectroscopy was applied to elucidate the molecular structures of the glass/matrix interface. The various interfaces and interphases were studied. It is found that the structure of the silane in a treating solution is important in determining the structure of the silane on glass fibers, influences the macroscopic properties of composites. The amount of silane on glass fibers, the state of hydrogen bonding, orientation, copolymerization of the organicfunctionality with the matrix, curing of the silane, and effect of water on the interface were investigated. It is shown that the molecular approach is useful to interpret and predict physicomechanical properties of composites

Local electronic structure at organic–metal interface studied by UPS, MAES, and first-principles calculation

Energy Technology Data Exchange (ETDEWEB)

Aoki, M., E-mail: cmaoki@mail.ecc.u-tokyo.ac.jp; Masuda, S.

2015-10-01

Understanding and controlling local electronic structures at organic–metal interfaces are crucial for fabricating novel organic-based electronics, as in the case of heterojunctions in semiconductor devices. Here, we report recent studies of valence electronic states at organic–metal interfaces (especially those near the Fermi level of a metal substrate) by the combined analysis of ultraviolet photoemission spectroscopy (UPS), metastable atom electron spectroscopy (MAES), and first-principles calculations. New electronic states in the HOMO (highest occupied molecular orbital)–LUMO (lowest unoccupied molecular orbital) gap formed at an organic–metal interface are classified as a chemisorption-induced gap state (CIGS) and a complex-based gap state (CBGS). The CIGS is further characterized by an asymptotic feature of the metal wave function in the chemisorbed species. The CIGSs in alkanethiolates on Pt(1 1 1) and C{sub 60} on Pt(1 1 1) can be regarded as damping and propagating types, respectively. The CBGSs in K-doped dibenzopentacene (DBP) are composed of DBP-derived MOs and K sp states and distributed over the complex film. No metallic structures were found in the K{sub 1}DBP and K{sub 3}DBP phases, suggesting that they are Mott–Hubbard insulators due to strong electron correlation. The local electronic structures of a pentacene film bridged by Au electrodes under bias voltages were examined by an FET-like specimen. The pentacene-derived bands were steeply shifted at the positively biased electrode, reflecting the p-type character of the film.

High Performance Computing - Power Application Programming Interface Specification Version 1.4

Energy Technology Data Exchange (ETDEWEB)

Laros III, James H. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); DeBonis, David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Grant, Ryan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kelly, Suzanne M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Levenhagen, Michael J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Olivier, Stephen Lecler [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Pedretti, Kevin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2016-10-01

Measuring and controlling the power and energy consumption of high performance computing systems by various components in the software stack is an active research area [13, 3, 5, 10, 4, 21, 19, 16, 7, 17, 20, 18, 11, 1, 6, 14, 12]. Implementations in lower level software layers are beginning to emerge in some production systems, which is very welcome. To be most effective, a portable interface to measurement and control features would significantly facilitate participation by all levels of the software stack. We present a proposal for a standard power Application Programming Interface (API) that endeavors to cover the entire software space, from generic hardware interfaces to the input from the computer facility manager.

NESSUS/NASTRAN Interface

Science.gov (United States)

Millwater, Harry; Riha, David

1996-01-01

The NESSUS probabilistic analysis computer program has been developed with a built-in finite element analysis program NESSUS/FEM. However, the NESSUS/FEM program is specialized for engine structures and may not contain sufficient features for other applications. In addition, users often become well acquainted with a particular finite element code and want to use that code for probabilistic structural analysis. For these reasons, this work was undertaken to develop an interface between NESSUS and NASTRAN such that NASTRAN can be used for the finite element analysis and NESSUS can be used for the probabilistic analysis. In addition, NESSUS was restructured such that other finite element codes could be more easily coupled with NESSUS. NESSUS has been enhanced such that NESSUS will modify the NASTRAN input deck for a given set of random variables, run NASTRAN and read the NASTRAN result. The coordination between the two codes is handled automatically. The work described here was implemented within NESSUS 6.2 which was delivered to NASA in September 1995. The code runs on Unix machines: Cray, HP, Sun, SGI and IBM. The new capabilities have been implemented such that a user familiar with NESSUS using NESSUS/FEM and NASTRAN can immediately use NESSUS with NASTRAN. In other words, the interface with NASTRAN has been implemented in an analogous manner to the interface with NESSUS/FEM. Only finite element specific input has been changed. This manual is written as an addendum to the existing NESSUS 6.2 manuals. We assume users have access to NESSUS manuals and are familiar with the operation of NESSUS including probabilistic finite element analysis. Update pages to the NESSUS PFEM manual are contained in Appendix E. The finite element features of the code and the probalistic analysis capabilities are summarized.

Isostructural solid-solid phase transition in monolayers of soft core-shell particles at fluid interfaces: structure and mechanics.

Science.gov (United States)

Rey, Marcel; Fernández-Rodríguez, Miguel Ángel; Steinacher, Mathias; Scheidegger, Laura; Geisel, Karen; Richtering, Walter; Squires, Todd M; Isa, Lucio

2016-04-21

We have studied the complete two-dimensional phase diagram of a core-shell microgel-laden fluid interface by synchronizing its compression with the deposition of the interfacial monolayer. Applying a new protocol, different positions on the substrate correspond to different values of the monolayer surface pressure and specific area. Analyzing the microstructure of the deposited monolayers, we discovered an isostructural solid-solid phase transition between two crystalline phases with the same hexagonal symmetry, but with two different lattice constants. The two phases corresponded to shell-shell and core-core inter-particle contacts, respectively; with increasing surface pressure the former mechanically failed enabling the particle cores to come into contact. In the phase-transition region, clusters of particles in core-core contacts nucleate, melting the surrounding shell-shell crystal, until the whole monolayer moves into the second phase. We furthermore measured the interfacial rheology of the monolayers as a function of the surface pressure using an interfacial microdisk rheometer. The interfaces always showed a strong elastic response, with a dip in the shear elastic modulus in correspondence with the melting of the shell-shell phase, followed by a steep increase upon the formation of a percolating network of the core-core contacts. These results demonstrate that the core-shell nature of the particles leads to a rich mechanical and structural behavior that can be externally tuned by compressing the interface, indicating new routes for applications, e.g. in surface patterning or emulsion stabilization.

Chain-Branching Control of the Atomic Structure of Alkanethiol-Based Gold–Sulfur Interfaces

DEFF Research Database (Denmark)

Wang, Yun; Chi, Qijin; Zhang, Jingdong

2011-01-01

Density functional theory structure calculations at 0 K and simulations at 300 K of observed high-resolution in situ scanning tunneling microscopy (STM) images reveal three different atomic-interface structures for the self-assembled monolayers (SAMs) of three isomeric butanethiols on Au(111......): direct binding to the Au(111) surface without pitting, binding to adatoms above a regular surface with extensive pitting, and binding to adatoms with local surface vacancies and some pitting. Thermal motions are shown to produce some observed STM features, with a very tight energy balance controlling...

Phase constitution and interface structure of nano-sized Ag-Cu/AlN multilayers: Experiment and ab initio modeling

Energy Technology Data Exchange (ETDEWEB)

Pigozzi, Giancarlo; Janczak-Rusch, Jolanta; Passerone, Daniele; Antonio Pignedoli, Carlo; Patscheider, Joerg; Jeurgens, Lars P. H. [Empa, Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland); Antusek, Andrej [Empa, Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland); Faculty of Materials Science and Technology, Slovak University of Technology in Bratislava, Paulinska 16, 917 24 Trnava (Slovakia); Parlinska-Wojtan, Magdalena [Empa, Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland); University of Rzeszow, Institute of Physics, ul. Rejtana 16a, 35-959 Rzeszow (Poland); Bissig, Vinzenz [Kirsten Soldering AG, Hinterbergstrasse 32, CH-6330 Cham (Switzerland)

2012-10-29

Nano-sized Ag-Cu{sub 8nm}/AlN{sub 10nm} multilayers were deposited by reactive DC sputtering on {alpha}-Al{sub 2}O{sub 3}(0001) substrates. Investigation of the phase constitution and interface structure of the multilayers evidences a phase separation of the alloy sublayers into nanosized grains of Ag and Cu. The interfaces between the Ag grains and the quasi-single-crystalline AlN sublayers are semi-coherent, whereas the corresponding Cu/AlN interfaces are incoherent. The orientation relationship between Ag and AlN is constant throughout the entire multilayer stack. These observations are consistent with atomistic models of the interfaces as obtained by ab initio calculations.

Interface Mediated Nucleation and Growth of Dislocations in fcc-bcc nanocomposite

Science.gov (United States)

Zhang, Ruifeng; Wang, Jian; Beyerlein, Irene J.; Germann, Timothy C.

2011-03-01

Heterophase interfaces play a crucial role in determining material strength for nanostructured materials because they can block, store, nucleate, and remove dislocations, the essential defects that enable plastic deformation. Much recent theoretical and experimental effort has been conducted on nanostructured Cu-Nb multilayer composites that exhibited extraordinarily high strength, ductility, and resistance to radiation and mechanical loading. In decreasing layer thicknesses to the order of a few tens of nanometers or less, the deformation behavior of such composites is mainly controlled by the Cu/Nb interface. In this work, we focus on the cooperative mechanisms of dislocation nucleation and growth from Cu/Nb interfaces, and their interaction with interface. Two types of experimentally observed Cu/Nb incoherent interfaces are comparatively studied. We found that the preferred dislocation nucleation sites are closely related to atomic interface structure, which in turn, depend on the orientation relationship. The activation stress and energies for an isolated Shockley dislocation loop of different sizes from specific interface sites depend strongly on dislocation size, atomic interface pattern, and loading conditions. Such findings provide important insight into the mechanical response of a wide range of fcc/bcc metallic nanocomposites via atomic interface design.

Energetic, structural and electronic properties of metal vacancies in strained AlN/GaN interfaces.

Science.gov (United States)

Kioseoglou, J; Pontikis, V; Komninou, Ph; Pavloudis, Th; Chen, J; Karakostas, Th

2015-04-01

AlN/GaN heterostructures have been studied using density-functional pseudopotential calculations yielding the formation energies of metal vacancies under the influence of local interfacial strains, the associated charge distribution and the energies of vacancy-induced electronic states. Interfaces are built normal to the polar direction of the wurtzite structure by joining two single crystals of AlN and GaN that are a few atomic layers thick; thus, periodic boundary conditions generate two distinct heterophase interfaces. We show that the formation energy of vacancies is a function of their distance from the interfaces: the vacancy-interface interaction is found repulsive or attractive, depending on the type of the interface. When the interaction is attractive, the vacancy formation energy decreases with increasing the associated electric charge, and hence the equilibrium vacancy concentration at the interface is greater. This finding can reveal the well-known morphological differences existing between the two types of investigated interfaces. Moreover, we found that the electric charge is strongly localized around the Ga vacancy, while in the case of Al vacancies is almost uniformly distributed throughout the AlN/GaN heterostructure. Crucially, for the applications of heterostructures, metal vacancies introduce deep states in the calculated bandgap at energy levels from 0.5 to 1 eV above the valence band maximum (VBM). It is, therefore, predicted that vacancies could initiate 'green luminescence' i.e. light emission in the energy range of 2.5 eV stemming from electronic transitions between these extra levels, and the conduction band, or energy levels, due to shallow donors.

S-LINK, a data link interface specification for the LHC era

International Nuclear Information System (INIS)

Bij, H.C. van der; McLaren, R.A.; Boyle, O.

1996-01-01

In the Technical Proposals for ATLAS, CMS and ALICE there is a requirement for several thousand data links. Although there is an obvious need for standardization, this seems difficult to achieve as the links run at different speeds, over different distances and have various constraints of power consumption, size and radiation hardness. An additional complication is that today we cannot decide which will be the most cost effective technology for the implementation of the final links. Furthermore, we must allow designers of boards at each end of the link, for example readout electronics and input buffers, to work in parallel with the development of the links. The S-LINK is a new concept which should provide the benefits of standardization without the limitations. The S-LINK specification defines, at both ends of the link, a simple FIFO-like user interface which remains independent of the technology used to implement the physical link. The physical link provides transfer of event data and control words, error detection, optional flow control and test facilities. This paper describes the S-LINK specification and gives examples of the use of the S-LINK, the physical links being designed, and the test equipment that is being developed

ACPYPE - AnteChamber PYthon Parser interfacE.

Science.gov (United States)

Sousa da Silva, Alan W; Vranken, Wim F

2012-07-23

ACPYPE (or AnteChamber PYthon Parser interfacE) is a wrapper script around the ANTECHAMBER software that simplifies the generation of small molecule topologies and parameters for a variety of molecular dynamics programmes like GROMACS, CHARMM and CNS. It is written in the Python programming language and was developed as a tool for interfacing with other Python based applications such as the CCPN software suite (for NMR data analysis) and ARIA (for structure calculations from NMR data). ACPYPE is open source code, under GNU GPL v3, and is available as a stand-alone application at http://www.ccpn.ac.uk/acpype and as a web portal application at http://webapps.ccpn.ac.uk/acpype. We verified the topologies generated by ACPYPE in three ways: by comparing with default AMBER topologies for standard amino acids; by generating and verifying topologies for a large set of ligands from the PDB; and by recalculating the structures for 5 protein-ligand complexes from the PDB. ACPYPE is a tool that simplifies the automatic generation of topology and parameters in different formats for different molecular mechanics programmes, including calculation of partial charges, while being object oriented for integration with other applications.

Characterization of interfaces in semimagnetic quantum wells

International Nuclear Information System (INIS)

Schmitt, G.; Kuhn-Heinrich, B.; Zehnder, U.; Ossau, W.; Litz, T.; Waag, A.; Landwehr, G.

1995-01-01

The interfaces between nonmagnetic CdTe quantum wells and semimagnetic barriers of Cd 1-x Mn x Te were investigated for several well widths by low temperature photoluminescence and photoluminescence excitation spectroscopy. Specially designed Cd 1-x Mn x /CdTe/Cd 1-y Mg y Te structures enable us to distinguish the quality of semimagnetic normal and inverted interfaces. The normal interface shows to better structural quality than the inverted interface. (author)

Complex Interfaces Under Change

DEFF Research Database (Denmark)

Rosbjerg, Dan

The hydrosphere is dynamic across the major compartments of the Earth system: the atmosphere, the oceans and seas, the land surface water, and the groundwater within the strata below the two last compartments. The global geography of the hydrosphere essentially depends on thermodynamic and mechan...... these interfaces and interfaced compartments and processes. Climate, sea-level, oceanographic currents and hydrological processes are all affected, while anthropogenic changes are often intense in the geographic settings corresponding to such interfaces....... and mechanical processes that develop within this structure. Water-related processes at the interfaces between the compartments are complex, depending both on the interface itself, and on the characteristics of the interfaced compartments. Various aspects of global change directly or indirectly impact...

Investigation of the atomic interface structure of mesotaxial Si/CoSi2(100) layers formed by high-dose implantation

International Nuclear Information System (INIS)

Bulle-Lieuwma, C.W.T.; Jong, A.F. de; Vandenhoudt, D.E.W.

1991-01-01

Aligned mesotaxial films of CoSi 2 in monocrystalline (100) oriented Si substrates have been formed by high-dose ion implantation of Co, followed by a high temperature treatment. The atomic structures of both the lower and upper Si/CoSi 2 (100) interfaces of the buried CoSi 2 layer have been investigated by high-resolution electron microscopy (HREM) combined with image simulations. A domain-like structure is observed consisting of areas with different interfaces. In order to derive the atomic configuration, image simulations of different proposed models are presented. By comparing simulated images and HREM images, two different atomic structure models for the Si/CoSi 2 (100) interface have been found. In the first model the interfacial Co atoms are six-fold coordinated and the tetrahedral coordination and bond lengths of silicon atoms are everywhere maintained. In the second model we found evidence for a 2 x 1 interface reconstruction, involving a difference in composition. The interfacial Co atoms are seven-fold coordinated. It is shown that the boundaries between the domains are associated with interfacial dislocations of edge-type with Burgers vectors b a/4 inclined and b = a/2 parallel to the interfacial plane. (author)

Surface and interface sciences of Li-ion batteries. -Research progress in electrode-electrolyte interface-

Science.gov (United States)

Minato, Taketoshi; Abe, Takeshi

2017-12-01

The application potential of Li-ion batteries is growing as demand increases in different fields at various stages in energy systems, in addition to their conventional role as power sources for portable devices. In particular, applications in electric vehicles and renewable energy storage are increasing for Li-ion batteries. For these applications, improvements in battery performance are necessary. The Li-ion battery produces and stores electric power from the electrochemical redox reactions between the electrode materials. The interface between the electrodes and electrolyte strongly affects the battery performance because the charge transfer causing the electrode redox reaction begins at this interface. Understanding of the surface structure, electronic structure, and chemical reactions at the electrode-electrolyte interface is necessary to improve battery performance. However, the interface is located between the electrode and electrolyte materials, hindering the experimental analysis of the interface; thus, the physical properties and chemical processes have remained poorly understood until recently. Investigations of the physical properties and chemical processes at the interface have been performed using advanced surface science techniques. In this review, current knowledge and future research prospects regarding the electrode-electrolyte interface are described for the further development of Li-ion batteries.

The Ni-YSZ interface

DEFF Research Database (Denmark)

Jensen, Karin Vels

The anode/electrolyte interface in solid oxide fuel cells (SOFC) is known to cause electrical losses. Geometrically simple Ni/yttria-stabilised zirconia (YSZ) interfaces were examined to gain information on the structural and chemical changes occurring during experiments at 1000°C in an atmosphere...... of 97% H2/3% H2O. Electrochemical impedance spectroscopy at open circuit voltage (OCV) and at anodic and cathodic polarisations (100 mV) was performed. A correlation of the electrical data with the structure development and the chemical composition was attempted. Nickel wires with different impurity...... between polarised and non-polarised samples. With pure nickel wires, however, the microstructures depended on the polarisation/non-polarisation conditions. At non-polarised conditions a hill and valley type structure was found. Anodic polarisation produced an up to 1 μm thick interface layer consisting...

Structural Insights into the Quadruplex-Duplex 3' Interface Formed from a Telomeric Repeat: A Potential Molecular Target.

Science.gov (United States)

Russo Krauss, Irene; Ramaswamy, Sneha; Neidle, Stephen; Haider, Shozeb; Parkinson, Gary N

2016-02-03

We report here on an X-ray crystallographic and molecular modeling investigation into the complex 3' interface formed between putative parallel stranded G-quadruplexes and a duplex DNA sequence constructed from the human telomeric repeat sequence TTAGGG. Our crystallographic approach provides a detailed snapshot of a telomeric 3' quadruplex-duplex junction: a junction that appears to have the potential to form a unique molecular target for small molecule binding and interference with telomere-related functions. This unique target is particularly relevant as current high-affinity compounds that bind putative G-quadruplex forming sequences only rarely have a high degree of selectivity for a particular quadruplex. Here DNA junctions were assembled using different putative quadruplex-forming scaffolds linked at the 3' end to a telomeric duplex sequence and annealed to a complementary strand. We successfully generated a series of G-quadruplex-duplex containing crystals, both alone and in the presence of ligands. The structures demonstrate the formation of a parallel folded G-quadruplex and a B-form duplex DNA stacked coaxially. Most strikingly, structural data reveals the consistent formation of a TAT triad platform between the two motifs. This triad allows for a continuous stack of bases to link the quadruplex motif with the duplex region. For these crystal structures formed in the absence of ligands, the TAT triad interface occludes ligand binding at the 3' quadruplex-duplex interface, in agreement with in silico docking predictions. However, with the rearrangement of a single nucleotide, a stable pocket can be produced, thus providing an opportunity for the binding of selective molecules at the interface.

The core structures of transformation dislocations at TiAl/Ti3Al interfaces

International Nuclear Information System (INIS)

Penisson, J.M.; Loubradou, M.; Derder, C.; Bonnet, R.

1993-01-01

A Ti-40%Al alloy is investigated using High Resolution Electron Microscopy. The alloy structure consists mainly of alternate lamellae of γ(TiAl, L1 0 structure) and α 2 (Ti 3 Al, DO 19 structure) phases. These lamellae are parallel to each other and the interfaces between them are flat and parallel to the densest planes of the crystals. It is found that, among the variety of interfacial dislocations relieving the misfit, some have cores involving four (111) planes in height. The elastic displacement fields around these interfacial ledges, compared with the experimental atomic positions determined from HREM images, are in agreement with Burgers vector contents 1/6 left angle 112 right angle . (orig.)

Beyond the continuum: how molecular solvent structure affects electrostatics and hydrodynamics at solid-electrolyte interfaces.

Science.gov (United States)

Bonthuis, Douwe Jan; Netz, Roland R

2013-10-03

Standard continuum theory fails to predict several key experimental results of electrostatic and electrokinetic measurements at aqueous electrolyte interfaces. In order to extend the continuum theory to include the effects of molecular solvent structure, we generalize the equations for electrokinetic transport to incorporate a space dependent dielectric profile, viscosity profile, and non-electrostatic interaction potential. All necessary profiles are extracted from atomistic molecular dynamics (MD) simulations. We show that the MD results for the ion-specific distribution of counterions at charged hydrophilic and hydrophobic interfaces are accurately reproduced using the dielectric profile of pure water and a non-electrostatic repulsion in an extended Poisson-Boltzmann equation. The distributions of Na(+) at both surface types and Cl(-) at hydrophilic surfaces can be modeled using linear dielectric response theory, whereas for Cl(-) at hydrophobic surfaces it is necessary to apply nonlinear response theory. The extended Poisson-Boltzmann equation reproduces the experimental values of the double-layer capacitance for many different carbon-based surfaces. In conjunction with a generalized hydrodynamic theory that accounts for a space dependent viscosity, the model captures the experimentally observed saturation of the electrokinetic mobility as a function of the bare surface charge density and the so-called anomalous double-layer conductivity. The two-scale approach employed here-MD simulations and continuum theory-constitutes a successful modeling scheme, providing basic insight into the molecular origins of the static and kinetic properties of charged surfaces, and allowing quantitative modeling at low computational cost.

Electronic structure and lattice dynamics at the interface of single layer FeSe and SrTiO3

Science.gov (United States)

Ahmed, Towfiq; Balatsky, Alexander; Zhu, Jian-Xin

Recent discovery of high-temperature superconductivity with the superconducting energy gap opening at temperatures close to or above the liquid nitrogen boiling point in the single-layer FeSe grown on SrTiO3 has attracted significant interest. It suggests that the interface effects can be utilized to enhance the superconductivity. It has been shown recently that the coupling between the electrons in FeSe and vibrational modes at the interface play an important role. Here we report on a detailed study of electronic structure and lattice dynamics in the single-layer FeSe/SrTiO3 interface by using the state-of-art electronic structure method within the density functional theory. The nature of the vibrational modes at the interface and their coupling to the electronic degrees of freedom are analyzed. In addition, the effect of hole and electron doping in SrTiO3 on the electron-mode coupling strength is also considered. This work was carried out under the auspices of the National Nuclear Security Administration of the U.S. DOE at LANL under Contract No. DE-AC52-06NA25396, and was supported by the DOE Office of Basic Energy Sciences.

Surfaces and interfaces of electronic materials

CERN Document Server

Brillson, Leonard J

2012-01-01

An advanced level textbook covering geometric, chemical, and electronic structure of electronic materials, and their applications to devices based on semiconductor surfaces, metal-semiconductor interfaces, and semiconductor heterojunctions. Starting with the fundamentals of electrical measurements on semiconductor interfaces, it then describes the importance of controlling macroscopic electrical properties by atomic-scale techniques. Subsequent chapters present the wide range of surface and interface techniques available to characterize electronic, optical, chemical, and structural propertie

Metal/silicon Interfaces and Their Oxidation Behavior - Photoemission Spectroscopy Analysis.

Science.gov (United States)

Yeh, Jyh-Jye

Synchrotron radiation photoemission spectroscopy was used to study Ni/Si and Au/Si interface properties on the atomic scale at room temperature, after high temperature annealing and after oxygen exposures. Room temperature studies of metal/Si interfaces provide background for an understanding of the interface structure after elevated temperature annealing. Oxidation studies of Si surfaces covered with metal overlayers yield insight about the effect of metal atoms in the Si oxidation mechanisms and are useful in the identification of subtle differences in bonding relations between atoms at the metal/Si interfaces. Core level and valence band spectra with variable surface sensitivities were used to study the interactions between metal, Si, and oxygen for metal coverages and oxide thickness in the monolayer region. Interface morphology at the initial stage of metal/Si interface formation and after oxidation was modeled on the basis of the evolutions of metal and Si signals at different probing depths in the photoemission experiment. Both Ni/Si and Au/Si interfaces formed at room temperature have a diffusive region at the interface. This is composed of a layer of metal-Si alloy, formed by Si outdiffusion into the metal overlayer, above a layer of interstitial metal atoms in the Si substrate. Different atomic structures of these two regions at Ni/Si interface can account for the two different growth orientations of epitaxial Ni disilicides on the Si(111) surface after thermal annealing. Annealing the Au/Si interface at high temperature depletes all the Au atoms except for one monolayer of Au on the Si(111) surface. These phenomena are attributed to differences in the metal-Si chemical bonding relations associated with specific atomic structures. After oxygen exposures, both the Ni disilicide surface and Au covered Si surfaces (with different coverages and surface orderings) show silicon in higher oxidation states, in comparison to oxidized silicon on a clean surface

Understanding and Manipulating Electrostatic Fields at the Protein-Protein Interface Using Vibrational Spectroscopy and Continuum Electrostatics Calculations.

Science.gov (United States)

Ritchie, Andrew W; Webb, Lauren J

2015-11-05

Biological function emerges in large part from the interactions of biomacromolecules in the complex and dynamic environment of the living cell. For this reason, macromolecular interactions in biological systems are now a major focus of interest throughout the biochemical and biophysical communities. The affinity and specificity of macromolecular interactions are the result of both structural and electrostatic factors. Significant advances have been made in characterizing structural features of stable protein-protein interfaces through the techniques of modern structural biology, but much less is understood about how electrostatic factors promote and stabilize specific functional macromolecular interactions over all possible choices presented to a given molecule in a crowded environment. In this Feature Article, we describe how vibrational Stark effect (VSE) spectroscopy is being applied to measure electrostatic fields at protein-protein interfaces, focusing on measurements of guanosine triphosphate (GTP)-binding proteins of the Ras superfamily binding with structurally related but functionally distinct downstream effector proteins. In VSE spectroscopy, spectral shifts of a probe oscillator's energy are related directly to that probe's local electrostatic environment. By performing this experiment repeatedly throughout a protein-protein interface, an experimental map of measured electrostatic fields generated at that interface is determined. These data can be used to rationalize selective binding of similarly structured proteins in both in vitro and in vivo environments. Furthermore, these data can be used to compare to computational predictions of electrostatic fields to explore the level of simulation detail that is necessary to accurately predict our experimental findings.

SFG analysis of the molecular structures at the surfaces and buried interfaces of PECVD ultralow-dielectric constant pSiCOH

Science.gov (United States)

Zhang, Xiaoxian; Myers, John N.; Huang, Huai; Shobha, Hosadurga; Chen, Zhan; Grill, Alfred

2016-02-01

PECVD deposited porous SiCOH with ultralow dielectric constant has been successfully integrated as the insulator in advanced interconnects to decrease the RC delay. The effects of NH3 plasma treatment and the effectiveness of the dielectric repair on molecular structures at the surface and buried interface of a pSiCOH film deposited on top of a SiCNH film on a Si wafer were fully characterized using sum frequency generation vibrational spectroscopy (SFG), supplemented by X-ray photoelectron spectroscopy. After exposure to NH3 plasma for 18 s, about 40% of the methyl groups were removed from the pSiCOH surface, and the average orientation of surface methyl groups tilted more towards the surface. The repair method used here effectively repaired the molecular structures at the pSiCOH surface but did not totally recover the entire plasma-damaged layer. Additionally, simulated SFG spectra with various average orientations of methyl groups at the SiCNH/pSiCOH buried interface were compared with the experimental SFG spectra collected using three different laser input angles to determine the molecular structural information at the SiCNH/pSiCOH buried interface after NH3 plasma treatment and repair. The molecular structures including the coverage and the average orientation of methyl groups at the buried interface were found to be unchanged by NH3 plasma treatment and repair.

Adaptive Crack Modeling with Interface Solid Elements for Plain and Fiber Reinforced Concrete Structures.

Science.gov (United States)

Zhan, Yijian; Meschke, Günther

2017-07-08

The effective analysis of the nonlinear behavior of cement-based engineering structures not only demands physically-reliable models, but also computationally-efficient algorithms. Based on a continuum interface element formulation that is suitable to capture complex cracking phenomena in concrete materials and structures, an adaptive mesh processing technique is proposed for computational simulations of plain and fiber-reinforced concrete structures to progressively disintegrate the initial finite element mesh and to add degenerated solid elements into the interfacial gaps. In comparison with the implementation where the entire mesh is processed prior to the computation, the proposed adaptive cracking model allows simulating the failure behavior of plain and fiber-reinforced concrete structures with remarkably reduced computational expense.

Interface, a dispersed architecture

NARCIS (Netherlands)

Vissers, C.A.

1976-01-01

Past and current specification techniques use timing diagrams and written text to describe the phenomenology of an interface. This paper treats an interface as the architecture of a number of processes, which are dispersed over the related system parts and the message path. This approach yields a

Microscopic properties of ionic liquid/organic semiconductor interfaces revealed by molecular dynamics simulations.

Science.gov (United States)

Yokota, Yasuyuki; Miyamoto, Hiroo; Imanishi, Akihito; Takeya, Jun; Inagaki, Kouji; Morikawa, Yoshitada; Fukui, Ken-Ichi

2018-05-09

Electric double-layer transistors based on ionic liquid/organic semiconductor interfaces have been extensively studied during the past decade because of their high carrier densities at low operation voltages. Microscopic structures and the dynamics of ionic liquids likely determine the device performance; however, knowledge of these is limited by a lack of appropriate experimental tools. In this study, we investigated ionic liquid/organic semiconductor interfaces using molecular dynamics to reveal the microscopic properties of ionic liquids. The organic semiconductors include pentacene, rubrene, fullerene, and 7,7,8,8-tetracyanoquinodimethane (TCNQ). While ionic liquids close to the substrate always form the specific layered structures, the surface properties of organic semiconductors drastically alter the ionic dynamics. Ionic liquids at the fullerene interface behave as a two-dimensional ionic crystal because of the energy gain derived from the favorable electrostatic interaction on the corrugated periodic substrate.

Carrier density modulation by structural distortions at modified LaAlO3/SrTiO3 interfaces

International Nuclear Information System (INIS)

Schoofs, Frank; Vickers, Mary E; Egilmez, Mehmet; Fix, Thomas; Kleibeuker, Josée E; MacManus-Driscoll, Judith L; Blamire, Mark G; Carpenter, Michael A

2013-01-01

In order to study the fundamental conduction mechanism of LaAlO 3 /SrTiO 3 (LAO/STO) interfaces, heterostructures were modified with a single unit cell interface layer of either an isovalent titanate ATiO 3 (A = Ca, Sr, Sn, Ba) or a rare earth modified Sr 0.5 RE 0.5 TiO 3 (RE = La, Nd, Sm, Dy) between the LAO and the STO. A strong coupling between the lattice strain induced in the LAO layer by the interfacial layers and the sheet carrier density in the STO substrate is observed. The observed crystal distortion of the LAO is large and it is suggested that it couples into the sub-surface STO, causing oxygen octahedral rotation and deformation. We propose that the ‘structural reconstruction’ which occurs in the STO surface as a result of the stress in the LAO is the enabling trigger for two-dimensional conduction at the LAO/STO interface by locally changing the band structure and releasing trapped carriers. (paper)

Electrical and structural properties of surfaces and interfaces in Ti/Al/Ni Ohmic contacts to p-type implanted 4H-SiC

Science.gov (United States)

Vivona, M.; Greco, G.; Bongiorno, C.; Lo Nigro, R.; Scalese, S.; Roccaforte, F.

2017-10-01

In this work, the electrical and structural properties of Ti/Al/Ni Ohmic contacts to p-type implanted silicon carbide (4H-SiC) were studied employing different techniques. With increasing the annealing temperature, an improvement of the electrical properties of the contacts is highlighted, until an Ohmic behavior is obtained at 950 °C, with a specific contact resistance ρc = 2.3 × 10-4 Ω cm2. A considerable intermixing of the metal layers occurred upon annealing, as a consequence of the formation of different phases, both in the uppermost part of the stack (mainly Al3Ni2) and at the interface with SiC, where the formation of preferentially aligned TiC is observed. The formation of an Ohmic contact was associated with the occurrence of the reaction and the disorder at the interface, where the current transport is dominated by the thermionic field emission mechanism with a barrier height of 0.56 eV.

Structural similarity and category-specificity

DEFF Research Database (Denmark)

Gerlach, Christian; Law, Ian; Paulson, Olaf B

2004-01-01

It has been suggested that category-specific recognition disorders for natural objects may reflect that natural objects are more structurally (visually) similar than artefacts and therefore more difficult to recognize following brain damage. On this account one might expect a positive relationshi...

Deriving a Mutation Index of Carcinogenicity Using Protein Structure and Protein Interfaces

Science.gov (United States)

Hakas, Jarle; Pearl, Frances; Zvelebil, Marketa

2014-01-01

With the advent of Next Generation Sequencing the identification of mutations in the genomes of healthy and diseased tissues has become commonplace. While much progress has been made to elucidate the aetiology of disease processes in cancer, the contributions to disease that many individual mutations make remain to be characterised and their downstream consequences on cancer phenotypes remain to be understood. Missense mutations commonly occur in cancers and their consequences remain challenging to predict. However, this knowledge is becoming more vital, for both assessing disease progression and for stratifying drug treatment regimes. Coupled with structural data, comprehensive genomic databases of mutations such as the 1000 Genomes project and COSMIC give an opportunity to investigate general principles of how cancer mutations disrupt proteins and their interactions at the molecular and network level. We describe a comprehensive comparison of cancer and neutral missense mutations; by combining features derived from structural and interface properties we have developed a carcinogenicity predictor, InCa (Index of Carcinogenicity). Upon comparison with other methods, we observe that InCa can predict mutations that might not be detected by other methods. We also discuss general limitations shared by all predictors that attempt to predict driver mutations and discuss how this could impact high-throughput predictions. A web interface to a server implementation is publicly available at http://inca.icr.ac.uk/. PMID:24454733

Neutron reflectivity as method to study in-situ adsorption of phospholipid layers to solid-liquid interfaces

DEFF Research Database (Denmark)

Gutberlet, Thomas; Klösgen, Beate Maria; Krastev, Rumen

2004-01-01

variation. It was observed that the method was capable of visualizing the adsorption of phospholipid layers to different solid-liquid interfaces and to resolve structural details at Angstroem resolution. The results depended strongly on a sufficiently good signal-to-noise ratio of the specific measurements......The use of neutron reflectivity as a method to study in-situ adsorption of phospholipid layers to solid-liquid interfaces was analyzed. The most important advantage of neutron reflectometry is the possibility to very the refractive index of the specific sample by isotope exchange, called contrast...

Characterization of interfaces in semimagnetic quantum wells

Energy Technology Data Exchange (ETDEWEB)

Schmitt, G.; Kuhn-Heinrich, B.; Zehnder, U.; Ossau, W.; Litz, T.; Waag, A.; Landwehr, G. [Physikalishes Institut der Universitaet Wuerzburg am Hubland, Wuerzburg (Germany)

1995-12-31

The interfaces between nonmagnetic CdTe quantum wells and semimagnetic barriers of Cd{sub 1-x}Mn{sub x}Te were investigated for several well widths by low temperature photoluminescence and photoluminescence excitation spectroscopy. Specially designed Cd{sub 1-x}Mn{sub x}/CdTe/Cd{sub 1-y} Mg{sub y}Te structures enable us to distinguish the quality of semimagnetic normal and inverted interfaces. The normal interface shows to better structural quality than the inverted interface. (author). 5 refs, 2 figs, 1 tab.

A Standard for Sharing and Accessing Time Series Data: The Heliophysics Application Programmers Interface (HAPI) Specification

Science.gov (United States)

Vandegriff, J. D.; King, T. A.; Weigel, R. S.; Faden, J.; Roberts, D. A.; Harris, B. T.; Lal, N.; Boardsen, S. A.; Candey, R. M.; Lindholm, D. M.

2017-12-01

We present the Heliophysics Application Programmers Interface (HAPI), a new interface specification that both large and small data centers can use to expose time series data holdings in a standard way. HAPI was inspired by the similarity of existing services at many Heliophysics data centers, and these data centers have collaborated to define a single interface that captures best practices and represents what everyone considers the essential, lowest common denominator for basic data access. This low level access can serve as infrastructure to support greatly enhanced interoperability among analysis tools, with the goal being simplified analysis and comparison of data from any instrument, model, mission or data center. The three main services a HAPI server must perform are 1. list a catalog of datasets (one unique ID per dataset), 2. describe the content of one dataset (JSON metadata), and 3. retrieve numerical content for one dataset (stream the actual data). HAPI defines both the format of the query to the server, and the response from the server. The metadata is lightweight, focusing on use rather than discovery, and the data format is a streaming one, with Comma Separated Values (CSV) being required and binary or JSON streaming being optional. The HAPI specification is available at GitHub, where projects are also underway to develop reference implementation servers that data providers can adapt and use at their own sites. Also in the works are data analysis clients in multiple languages (IDL, Python, Matlab, and Java). Institutions which have agreed to adopt HAPI include Goddard (CDAWeb for data and CCMC for models), LASP at the University of Colorado Boulder, the Particles and Plasma Interactions node of the Planetary Data System (PPI/PDS) at UCLA, the Plasma Wave Group at the University of Iowa, the Space Sector at the Johns Hopkins Applied Physics Lab (APL), and the tsds.org site maintained at George Mason University. Over the next year, the adoption of a

ACPYPE - AnteChamber PYthon Parser interfacE

Directory of Open Access Journals (Sweden)

Sousa da Silva Alan W

2012-07-01

Full Text Available Abstract Background ACPYPE (or AnteChamber PYthon Parser interfacE is a wrapper script around the ANTECHAMBER software that simplifies the generation of small molecule topologies and parameters for a variety of molecular dynamics programmes like GROMACS, CHARMM and CNS. It is written in the Python programming language and was developed as a tool for interfacing with other Python based applications such as the CCPN software suite (for NMR data analysis and ARIA (for structure calculations from NMR data. ACPYPE is open source code, under GNU GPL v3, and is available as a stand-alone application at http://www.ccpn.ac.uk/acpype and as a web portal application at http://webapps.ccpn.ac.uk/acpype. Findings We verified the topologies generated by ACPYPE in three ways: by comparing with default AMBER topologies for standard amino acids; by generating and verifying topologies for a large set of ligands from the PDB; and by recalculating the structures for 5 protein–ligand complexes from the PDB. Conclusions ACPYPE is a tool that simplifies the automatic generation of topology and parameters in different formats for different molecular mechanics programmes, including calculation of partial charges, while being object oriented for integration with other applications.

Dissecting the telomere-inner nuclear membrane interface formed in meiosis.

Science.gov (United States)

Pendlebury, Devon F; Fujiwara, Yasuhiro; Tesmer, Valerie M; Smith, Eric M; Shibuya, Hiroki; Watanabe, Yoshinori; Nandakumar, Jayakrishnan

2017-12-01

Tethering telomeres to the inner nuclear membrane (INM) allows homologous chromosome pairing during meiosis. The meiosis-specific protein TERB1 binds the telomeric protein TRF1 to establish telomere-INM connectivity and is essential for mouse fertility. Here we solve the structure of the human TRF1-TERB1 interface to reveal the structural basis for telomere-INM linkage. Disruption of this interface abrogates binding and compromises telomere-INM attachment in mice. An embedded CDK-phosphorylation site within the TRF1-binding region of TERB1 provides a mechanism for cap exchange, a late-pachytene phenomenon involving the dissociation of the TRF1-TERB1 complex. Indeed, further strengthening this interaction interferes with cap exchange. Finally, our biochemical analysis implicates distinct complexes for telomere-INM tethering and chromosome-end protection during meiosis. Our studies unravel the structure, stoichiometry, and physiological implications underlying telomere-INM tethering, thereby providing unprecedented insights into the unique function of telomeres in meiosis.

Dissecting the telomere–inner nuclear membrane interface formed in meiosis

Energy Technology Data Exchange (ETDEWEB)

Pendlebury, Devon F.; Fujiwara, Yasuhiro; Tesmer, Valerie M.; Smith, Eric M.; Shibuya, Hiroki; Watanabe, Yoshinori; Nandakumar, Jayakrishnan

2017-10-30

Tethering telomeres to the inner nuclear membrane (INM) allows homologous chromosome pairing during meiosis. The meiosis-specific protein TERB1 binds the telomeric protein TRF1 to establish telomere–INM connectivity and is essential for mouse fertility. Here we solve the structure of the human TRF1–TERB1 interface to reveal the structural basis for telomere–INM linkage. Disruption of this interface abrogates binding and compromises telomere–INM attachment in mice. An embedded CDK-phosphorylation site within the TRF1-binding region of TERB1 provides a mechanism for cap exchange, a late-pachytene phenomenon involving the dissociation of the TRF1–TERB1 complex. Indeed, further strengthening this interaction interferes with cap exchange. Finally, our biochemical analysis implicates distinct complexes for telomere–INM tethering and chromosome-end protection during meiosis. Our studies unravel the structure, stoichiometry, and physiological implications underlying telomere–INM tethering, thereby providing unprecedented insights into the unique function of telomeres in meiosis.

Molecular dynamic simulation of the atomic structure of aluminum solid–liquid interfaces

International Nuclear Information System (INIS)

Men, H; Fan, Z

2014-01-01

In this paper, molecular dynamic (MD) simulation was used to investigate the equilibrium atomic arrangement at aluminum solid–liquid (S/L) interfaces with {111}, {110} and {100} orientations. The simulation results reveal that the aluminum S/L interfaces are diffuse for all the orientations, and extend up to 7 atomic layers. Within the diffuse interfaces there exists substantial atomic ordering, which is manifested by atomic layering perpendicular to the interface and in-plane atomic ordering parallel to the interface. Atomic layering can be quantified by the atomic density profile (ρ(z)) while the in-plane atomic ordering can be described by the in-plane ordering parameter (S(z)). The detailed MD simulation suggests that atomic layering at the interface always occurs within 7 atomic layers independent of the interface orientation while the in-plane ordering is highly dependent on the interface orientations, with the {111} interface being less diffuse than the {100} and {110} interfaces. This study demonstrates clearly that the physical origin of the diffuse interface is atomic layering and in-plane atomic ordering at the S/L interfaces. It is suggested that the difference in atomic layering and in-plane ordering at the S/L interface with different orientations is responsible for the observed growth anisotropy. (papers)

Modeling and stabilities of Mg/MgH2 interfaces: A first-principles investigation

Directory of Open Access Journals (Sweden)

Jia-Jun Tang

2014-07-01

Full Text Available We have theoretically investigated the modeling and the structural stabilities of various Mg/MgH2 interfaces, i.e. Mg(101¯0/MgH2(210, Mg(0001/MgH2(101 and Mg(101¯0/MgH2(101, and provided illuminating insights into Mg/MgH2 interface. Specifically, the main factors, which impact the interfacial energies, are fully considered, including surface energies of two phases, mutual lattice constants of interface model, and relative position of two phases. The surface energies of Mg and MgH2, on the one hand, are found to be greatly impacting the interfacial energies, reflected by the lowest interfacial energy of Mg(0001/MgH2(101 which is comprised of two lowest energy surfaces. On the other hand, it is demonstrated that the mutual lattice constants and the relative position of two phases lead to variations of interfacial energies, thus influencing the interface stabilities dramatically. Moreover, the Mg-H bonding at interface is found to be the determinant of Mg/MgH2 interface stability. Lastly, interfacial and strain effects on defect formations are also studied, both of which are highly facilitating the defect formations. Our results provide a detailed insight into Mg/MgH2 interface structures and the corresponding stabilities.

Stimulus specificity of a steady-state visual-evoked potential-based brain-computer interface

Science.gov (United States)

Ng, Kian B.; Bradley, Andrew P.; Cunnington, Ross

2012-06-01

The mechanisms of neural excitation and inhibition when given a visual stimulus are well studied. It has been established that changing stimulus specificity such as luminance contrast or spatial frequency can alter the neuronal activity and thus modulate the visual-evoked response. In this paper, we study the effect that stimulus specificity has on the classification performance of a steady-state visual-evoked potential-based brain-computer interface (SSVEP-BCI). For example, we investigate how closely two visual stimuli can be placed before they compete for neural representation in the cortex and thus influence BCI classification accuracy. We characterize stimulus specificity using the four stimulus parameters commonly encountered in SSVEP-BCI design: temporal frequency, spatial size, number of simultaneously displayed stimuli and their spatial proximity. By varying these quantities and measuring the SSVEP-BCI classification accuracy, we are able to determine the parameters that provide optimal performance. Our results show that superior SSVEP-BCI accuracy is attained when stimuli are placed spatially more than 5° apart, with size that subtends at least 2° of visual angle, when using a tagging frequency of between high alpha and beta band. These findings may assist in deciding the stimulus parameters for optimal SSVEP-BCI design.

Energy Level Alignment at Aqueous GaN and ZnO Interfaces

Science.gov (United States)

Hybertsen, Mark S.; Kharche, Neerav; Muckerman, James T.

2014-03-01

Electronic energy level alignment at semiconductor-electrolyte interfaces is fundamental to electrochemical activity. Motivated in particular by the search for new materials that can be more efficient for photocatalysis, we develop a first principles method to calculate this alignment at aqueous interfaces and demonstrate it for the specific case of non-polar GaN and ZnO interfaces with water. In the first step, density functional theory (DFT) based molecular dynamics is used to sample the physical interface structure and to evaluate the electrostatic potential step at the interface. In the second step, the GW approach is used to evaluate the reference electronic energy level separately in the bulk semiconductor (valence band edge energy) and in bulk water (the 1b1 energy level), relative to the internal electrostatic energy reference. Use of the GW approach naturally corrects for errors inherent in the use of Kohn-Sham energy eigenvalues to approximate the electronic excitation energies in each material. With this predicted interface alignment, specific redox levels in water, with potentials known relative to the 1b1 level, can then be compared to the semiconductor band edge positions. Our results will be discussed in the context of experiments in which photoexcited GaN and ZnO drive the hydrogen evolution reaction. Research carried out at Brookhaven National Laboratory under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.

Hierarchy of on-orbit servicing interfaces

Science.gov (United States)

Moe, Rud V.

1989-01-01

A series of equipment interfaces is involved in on-orbit servicing operations. The end-to-end hierarchy of servicing interfaces is presented. The interface concepts presented include structure and handling, and formats for transfer of resources (power, data, fluids, etc.). Consequences on cost, performance, and service ability of the use of standard designs or unique designs with interface adapters are discussed. Implications of the interface designs compatibility with remote servicing using telerobotic servicers are discussed.

Atomic and electronic structure of a copper/graphene interface as prepared and 1.5 years after

Science.gov (United States)

Boukhvalov, D. W.; Bazylewski, P. F.; Kukharenko, A. I.; Zhidkov, I. S.; Ponosov, Yu. S.; Kurmaev, E. Z.; Cholakh, S. O.; Lee, Y. H.; Chang, G. S.

2017-12-01

We report the results of X-ray spectroscopy and Raman measurements of as-prepared graphene on a high quality copper surface and the same materials after 1.5 years under different conditions (ambient and low humidity). The obtained results were compared with density functional theory calculations of the formation energies and electronic structures of various structural defects in graphene/Cu interfaces. For evaluation of the stability of the carbon cover, we propose a two-step model. The first step is oxidation of the graphene, and the second is perforation of graphene with the removal of carbon atoms as part of the carbon dioxide molecule. Results of the modeling and experimental measurements provide evidence that graphene grown on high-quality copper substrate becomes robust and stable in time (1.5 years). However, the stability of this interface depends on the quality of the graphene and the number of native defects in the graphene and substrate. The effect of the presence of a metallic substrate with defects on the stability and electronic structure of graphene is also discussed

Molecular-structure control of ultrafast electron injection at cationic porphyrin-CdTe quantum dot interfaces

KAUST Repository

Aly, Shawkat Mohammede

2015-03-05

Charge transfer (CT) at donor (D)/acceptor (A) interfaces is central to the functioning of photovoltaic and light-emitting devices. Understanding and controlling this process on the molecular level has been proven to be crucial for optimizing the performance of many energy-challenge relevant devices. Here, we report the experimental observations of controlled on/off ultrafast electron transfer (ET) at cationic porphyrin-CdTe quantum dot (QD) interfaces using femto- and nanosecond broad-band transient absorption (TA) spectroscopy. The time-resolved data demonstrate how one can turn on/off the electron injection from porphyrin to the CdTe QDs. With careful control of the molecular structure, we are able to tune the electron injection at the porphyrin-CdTe QD interface from zero to very efficient and ultrafast. In addition, our data demonstrate that the ET process occurs within our temporal resolution of 120 fs, which is one of the fastest times recorded for organic photovoltaics. © 2015 American Chemical Society.

New Analytical Methods for the Surface/ Interface and the Micro-Structures in Advanced Nanocomposite Materials by Synchrotron Radiation

Directory of Open Access Journals (Sweden)

K. Nakamae

2010-12-01

Full Text Available Analytical methods of surface/interface structure and micro-structure in advanced nanocomposite materials by using the synchrotron radiation are introduced. Recent results obtained by the energy-tunable and highly collimated brilliant X-rays, in-situ wide angle/small angle X-ray diffraction with high accuracy are reviewed. It is shown that small angle X-ray scattering is one of the best methods to characterize nanoparticle dispersibility, filler aggregate/agglomerate structures and in-situ observation of hierarchical structure deformation in filled rubber under cyclic stretch. Grazing Incidence(small and wide angle X-ray Scattering are powerful to analyze the sintering process of metal nanoparticle by in-situ observation as well as the orientation of polymer molecules and crystalline orientation at very thin surface layer (ca 7nm of polymer film. While the interaction and conformation of adsorbed molecule at interface can be investigated by using high energy X-ray XPS with Enough deep position (ca 9 micron m.

Pinning-free GaAs MIS structures with Si interface control layers formed on (4 x 6) reconstructed (0 0 1) surface

Energy Technology Data Exchange (ETDEWEB)

Anantathanasarn, Sanguan; Hasegawa, Hideki

2003-06-30

(0 0 1)-Oriented GaAs metal-insulator-semiconductor (MIS) structures having a silicon interface control layer (Si ICL) were fabricated on surfaces having Ga-rich (4x6) reconstructions. Si ICL was grown by molecular beam epitaxy. MIS structures were fabricated by partially converting Si ICL to SiN{sub x} by direct nitridation, and further depositing a thick SiO{sub 2} layer on top as the main passivation dielectric by plasma-assisted chemical vapor deposition. Reflection high-energy electron diffraction, in situ X-ray photoelectron spectroscopy and MIS capacitance-voltage (C-V) techniques were used for characterization. The initial surface reconstruction was found to have a surprisingly strong effect on the degree of Fermi level pinning at the MIS interface. In contrast to the standard As-rich (2x4) surface, which results in strongly pinned MIS interfaces, the novel SiO{sub 2}/SiN{sub x}/Si ICL/GaAs MIS structures formed on ''genuine'' (4x6) surface realized complete unpinning of Fermi level over the entire band gap with a minimum interface state density of 4x10{sup 10} cm{sup -2} eV{sup -1} range.

Chemistry of the copper silicon interface

International Nuclear Information System (INIS)

Ford, M.J.; Sashin, V.A.; Nixon, K.

2002-01-01

Full text: Copper and silicon readily interdiffuse, even at room temperature, to form an interface which can be several nanometers thick. Over the years considerable effort has gone into investigating the diffusion process and chemical nature of the interface formed. Photoemission measurements give evidence for the formation of a stable suicide with a definite stoichiometry, Cu 3 Si. This is evidenced by splitting of the Si LVV Auger line and slight shifts and change in shape of the copper valence band density of states as measured by ultra-violet photoemission. In this paper we present calculations of the electronic structure of copper suicide, bulk copper and silicon, and preliminary measurements of the interface by electron momentum spectroscopy. Densities of states for copper and copper suicide are dominated by the copper 3d bands, and difference between the two compounds are relatively small. By contrast, the full band structures are quite distinct. Hence, experimental measurements of the full band structure of the copper on silicon interface, for example by EMS, have the potential to reveal the chemistry of the interface in a detailed way

Interface structure and properties of CNTs/Cu composites fabricated by electroless deposition and spark plasma sintering

Science.gov (United States)

Wang, Hu; Zhang, Zhao-Hui; Hu, Zheng-Yang; Song, Qi; Yin, Shi-Pan

2018-01-01

In this paper, we fabricated a novel copper matrix composites reinforced by carbon nanotubes (CNTs) using electroless deposition (ED) and spark plasma sintering technique. Microstructure, mechanical, electric conductivity, and thermal properties of the CNTs/Cu composites were investigated. The results show that a favorable interface containing C-O and O-Cu bond was formed between CNTs and matrix when the CNTs were coated with nano-Cu by ED method. Thus, we accomplished the uniformly dispersed CNTs in the CNTs/Cu powders and compacted composites, which eventually leads to the enhancement of the mechanical properties of the CNTs/Cu composites in the macro-scale environment. However, the interface structure can hinder the movement of carriers and free electrons and increase the interface thermal resistance, which leads to modest decrease of electrical and thermal conductivity of the CNTs/Cu composites.

Band offsets and electronic structures of interface between In{sub 0.5}Ga{sub 0.5}As and InP

Energy Technology Data Exchange (ETDEWEB)

Cai, Genwang [School of Physical Science and Engineering and Key Laboratory of Materials Physics of Ministry of Education of China, Zhengzhou University, Zhengzhou 450052 (China); College of Science, Henan University of Technology, Zhengzhou 450001 (China); Wang, Changhong; Wang, Weichao [College of Electronic Information and Optical Engineering, Nankai University, Tianjin 300071 (China); Liang, Erjun, E-mail: ejliang@zzu.edu.cn [School of Physical Science and Engineering and Key Laboratory of Materials Physics of Ministry of Education of China, Zhengzhou University, Zhengzhou 450052 (China)

2016-02-07

III–V semiconductor interfacing with high-κ gate oxide is crucial for the high mobility metal-oxide-semiconductor field transistor device. With density functional theory calculations, we explored the band offsets and electronic structures of the In{sub 0.5}Ga{sub 0.5}As/InP interfaces with various interfacial bondings. Among six different bonding interfaces, we found that P-In(Ga) bonding interface showed the highest stability. Local density of states calculations was adopted to calculate the band offsets. Except for the metallic interface, we noticed that neither valence band offset nor conduction band offset depended on the interfacial bondings. For the most stable P-In(Ga) interface, we did not observe any gap states. Furthermore, we explored the P-In(Ga) interfaces with interfacial P-As exchange defects, which slightly modified the interface stability and the band offsets but did not produce any gap states. These findings provide solid evidence that InP could serve as a promising interfacial passivation layer between III–V material and high-κ oxide in the application of high mobility devices.

Oxide nanoparticles in an Al-alloyed oxide dispersion strengthened steel: crystallographic structure and interface with ferrite matrix

Science.gov (United States)

Zhang, Zhenbo; Pantleon, Wolfgang

2017-07-01

Oxide nanoparticles are quintessential for ensuring the extraordinary properties of oxide dispersion strengthened (ODS) steels. In this study, the crystallographic structure of oxide nanoparticles, and their interface with the ferritic steel matrix in an Al-alloyed ODS steel, i.e. PM2000, were systematically investigated by high-resolution transmission electron microscopy. The majority of oxide nanoparticles were identified to be orthorhombic YAlO3. During hot consolidation and extrusion, they develop a coherent interface and a near cuboid-on-cube orientation relationship with the ferrite matrix in the material. After annealing at 1200 °C for 1 h, however, the orientation relationship between the oxide nanoparticles and the matrix becomes arbitrary, and their interface mostly incoherent. Annealing at 1300 °C leads to considerable coarsening of oxide nanoparticles, and a new orientation relationship of pseudo-cube-on-cube between oxide nanoparticles and ferrite matrix develops. The reason for the developing interfaces and orientation relationships between oxide nanoparticles and ferrite matrix under different conditions is discussed.

Structuring Formal Requirements Specifications for Reuse and Product Families

Science.gov (United States)

Heimdahl, Mats P. E.

2001-01-01

In this project we have investigated how formal specifications should be structured to allow for requirements reuse, product family engineering, and ease of requirements change, The contributions of this work include (1) a requirements specification methodology specifically targeted for critical avionics applications, (2) guidelines for how to structure state-based specifications to facilitate ease of change and reuse, and (3) examples from the avionics domain demonstrating the proposed approach.

X-ray absorption spectroscopy study on SiC-side interface structure of SiO2–SiC formed by thermal oxidation in dry oxygen

Science.gov (United States)

Isomura, Noritake; Kosaka, Satoru; Kataoka, Keita; Watanabe, Yukihiko; Kimoto, Yasuji

2018-06-01

Extended X-ray absorption fine structure (EXAFS) spectroscopy is demonstrated to measure the fine atomic structure of SiO2–SiC interfaces. The SiC-side of the interface can be measured by fabricating thin SiO2 films and using SiC-selective EXAFS measurements. Fourier transforms of the oscillations of the EXAFS spectra correspond to radial-structure functions and reveal a new peak of the first nearest neighbor of Si for m-face SiC, which does not appear in measurements of the Si-face. This finding suggests that the m-face interface could include a structure with shorter Si–C distances. Numerical calculations provide additional support for this finding.

Multi-interface roughness effects on electron mobility in a Ga0.5In0.5P/GaAs multisubband coupled quantum well structure

International Nuclear Information System (INIS)

Sahu, Trinath; Shore, K Alan

2009-01-01

We analyse the effect of interface roughness scattering on low temperature electron mobility μ n mediated by intersubband interactions in a multisubband coupled Ga 0.5 In 0.5 P/GaAs quantum well structure. We consider a barrier δ-doped double quantum well system in which the subband electron mobility is limited by the interface roughness scattering μ IR n and ionized impurity scattering μ imp n . We analyse the effect of the intersubband interaction and coupling of subband wavefunctions through the barrier on the intrasubband and intersubband transport scattering rates. We show that the intersubband interaction controls the roughness potential of different interfaces through the dielectric screening matrix. In the case of lowest subband occupancy, the mobility is mainly governed by the interface roughness of the central barrier. Whereas when two subbands are occupied, the interface roughness of the outer barrier predominates due to intersubband effects. The influence of the intersubband interaction also exhibits interesting results on the well width up to which the interface roughness dominates in a double quantum well structure

First-principles modeling of interfaces between solids with large lattice mismatch: The prototypical CoO(111)/Ni(111) interface

KAUST Repository

Grytsiuk, Sergii

2012-11-28

In this work we investigate the CoO(111)/Ni(111) interface by first-principles calculations, focusing on its structure and stability. To satisfy the approximate 5:6 ratio of the CoO and Ni lattice constants, we construct a supercell with 5×5 Co (O) and 6×6 Ni atoms per layer in the bulk regions. For the interface Ni layer and the adjacent Ni layer we consider different configurations and study the binding energy. We show for an ideal CoO interface terminated by 5×5 O atoms that the structure is more stable if there are 5×5 Ni atoms next to it instead of 6×6 as in the bulk. In addition, we observe that a transition layer with 31 or 33 Ni atoms located between the interface 5×5 Ni and bulk 6×6 Ni layers (which partially reflects the structures of both these layers) enhances the stability of the CoO/Ni interface. The electronic and magnetic modifications induced by the interface formation are discussed.

First-principles modeling of interfaces between solids with large lattice mismatch: The prototypical CoO(111)/Ni(111) interface

KAUST Repository

Grytsyuk, Sergiy; Peskov, Maxim; Schwingenschlö gl, Udo

2012-01-01

In this work we investigate the CoO(111)/Ni(111) interface by first-principles calculations, focusing on its structure and stability. To satisfy the approximate 5:6 ratio of the CoO and Ni lattice constants, we construct a supercell with 5×5 Co (O) and 6×6 Ni atoms per layer in the bulk regions. For the interface Ni layer and the adjacent Ni layer we consider different configurations and study the binding energy. We show for an ideal CoO interface terminated by 5×5 O atoms that the structure is more stable if there are 5×5 Ni atoms next to it instead of 6×6 as in the bulk. In addition, we observe that a transition layer with 31 or 33 Ni atoms located between the interface 5×5 Ni and bulk 6×6 Ni layers (which partially reflects the structures of both these layers) enhances the stability of the CoO/Ni interface. The electronic and magnetic modifications induced by the interface formation are discussed.

The molecule-metal interface

CERN Document Server

Koch, Norbert; Wee, Andrew Thye Shen

2013-01-01

Reviewing recent progress in the fundamental understanding of the molecule-metal interface, this useful addition to the literature focuses on experimental studies and introduces the latest analytical techniques as applied to this interface.The first part covers basic theory and initial principle studies, while the second part introduces readers to photoemission, STM, and synchrotron techniques to examine the atomic structure of the interfaces. The third part presents photoelectron spectroscopy, high-resolution UV photoelectron spectroscopy and electron spin resonance to study the electroni

DFT calculations of strain and interface effects on electronic structures and magnetic properties of L10-FePt/Ag heterojunction of GMR applications

Science.gov (United States)

Pramchu, Sittichain; Jaroenjittichai, Atchara Punya; Laosiritaworn, Yongyut

2018-03-01

In this work, density functional theory (DFT) was employed to investigate the effect of strain and interface on electronic structures and magnetic properties of L10-FePt/Ag heterojunction. Two possible interface structures of L10-FePt(001)/Ag(001), that is, interface between Fe and Ag layers (Fe/Ag) and between Pt and Ag layers (Pt/Ag), were inspected. It was found that Pt/Ag interface is more stable than Fe/Ag interface due to its lower formation energy. Further, under the lattice mismatch induced tensile strain, the enhancement of magnetism for both Fe/Ag and Pt/Ag interface structures has been found to have progressed, though the magnetic moments of "interfacial" Fe and Pt atoms have been found to have decreased. To explain this further, the local density of states (LDOS) analysis suggests that interaction between Fe (Pt) and Ag near Fe/Ag (Pt/Ag) interface leads to spin symmetry breaking of the Ag atom and hence induces magnetism magnitude. In contrast, the magnetic moments of interfacial Fe and Pt atoms reduce because of the increase in the electronic states near the Fermi level of the minority-spin electrons. In addition, the significant enhancements of the LDOS near the Fermi levels of the minority-spin electrons signify the boosting of the transport properties of the minority-spin electrons and hence the spin-dependent electron transport at this ferromagnet/metal interface. From this work, it is expected that this clarification of the interfacial magnetism may inspire new innovation on how to improve spin-dependent electron transport for enhancing the giant magnetoresistance (GMR) ratio of potential GMR-based spintronic devices.

DFT calculations of strain and interface effects on electronic structures and magnetic properties of L10-FePt/Ag heterojunction of GMR applications

Directory of Open Access Journals (Sweden)

Sittichain Pramchu

2018-03-01

Full Text Available In this work, density functional theory (DFT was employed to investigate the effect of strain and interface on electronic structures and magnetic properties of L10-FePt/Ag heterojunction. Two possible interface structures of L10-FePt(001/Ag(001, that is, interface between Fe and Ag layers (Fe/Ag and between Pt and Ag layers (Pt/Ag, were inspected. It was found that Pt/Ag interface is more stable than Fe/Ag interface due to its lower formation energy. Further, under the lattice mismatch induced tensile strain, the enhancement of magnetism for both Fe/Ag and Pt/Ag interface structures has been found to have progressed, though the magnetic moments of “interfacial” Fe and Pt atoms have been found to have decreased. To explain this further, the local density of states (LDOS analysis suggests that interaction between Fe (Pt and Ag near Fe/Ag (Pt/Ag interface leads to spin symmetry breaking of the Ag atom and hence induces magnetism magnitude. In contrast, the magnetic moments of interfacial Fe and Pt atoms reduce because of the increase in the electronic states near the Fermi level of the minority-spin electrons. In addition, the significant enhancements of the LDOS near the Fermi levels of the minority-spin electrons signify the boosting of the transport properties of the minority-spin electrons and hence the spin-dependent electron transport at this ferromagnet/metal interface. From this work, it is expected that this clarification of the interfacial magnetism may inspire new innovation on how to improve spin-dependent electron transport for enhancing the giant magnetoresistance (GMR ratio of potential GMR-based spintronic devices.

Susy Les Houches accord: Interfacing SUSY spectrum calculators, decay packages, and event generators

International Nuclear Information System (INIS)

Skands, P.; Allanach, B.C.; Baer, H.

2003-11-01

An accord specifying generic file structures for 1) supersymmetric model specifications and input parameters, 2) electroweak scale supersymmetric mass and coupling spectra, and 3) decay tables is defined, to provide a universal interface between spectrum calculation programs, decay packages, and high energy physics event generators. (orig.)

Interfacial potential approach for Ag/ZnO (0001) interfaces

International Nuclear Information System (INIS)

Song Hong-Quan; Shen Jiang; Qian Ping; Chen Nan-Xian

2014-01-01

Systematic approaches are presented to extract the interfacial potentials from the ab initio adhesive energy of the interface system by using the Chen—Möbius inversion method. We focus on the interface structure of the metal (111)/ZnO (0001) in this work. The interfacial potentials of Ag—Zn and Ag—O are obtained. These potentials can be used to solve some problems about Ag/ZnO interfacial structure. Three metastable interfacial structures are investigated in order to check these potentials. Using the interfacial potentials we study the procedure of interface fracture in the Ag/ZnO (0001) interface and discuss the change of the energy, stress, and atomic structures in tensile process. The result indicates that the exact misfit dislocation reduces the total energy and softens the fracture process. Meanwhile, the formation and mobility of the vacancy near the interface are observed. (condensed matter: structural, mechanical, and thermal properties)

On the profile of frequency and voltage dependent interface states and series resistance in MIS structures

Energy Technology Data Exchange (ETDEWEB)

Doekme, Ilbilge [Science Education Department, Faculty of Kirsehir Education, Gazi University, Kirsehir (Turkey)]. E-mail: ilbilgedokme@gazi.edu.tr; Altindal, Semsettin [Physics Department, Faculty of Arts and Sciences, Gazi University, 06500, Teknikokullar, Ankara (Turkey)

2007-04-30

The variation in the capacitance-voltage (C-V) and conductance-voltage (G/{omega}-V) characteristics of Au/SiO{sub 2}/n-Si metal-insulator-semiconductor (MIS) structure have been systematically investigated as a function of frequencies in the frequency range 0.5 kHz-10 MHz at room temperature. In addition, the forward and reverse bias current-voltage (I-V) characteristics of this structure were measured at room temperature. The high value of ideality factor was attributed to the high density of interface states localized at Si/SiO{sub 2} interface and interfacial oxide layer. The density of interface states (N{sub ss}) and the series resistance (R{sub ss}) were calculated from I-V and C-V measurements using different methods and the effect of them on C-V and G/{omega}-V characteristics were deeply researched. At the same energy position near the top of valance band, the calculated N{sub ss} values, obtained without taking into account the series resistance of the devices almost one order of magnitude larger than N{sub ss} values obtained by taking into account R{sub ss} values. It is found that the C-V and G/{omega}-V curves exhibit a peak at low frequencies and the peak values of C and G/{omega} decrease with increasing frequency. Also, the plots of R {sub s} as a function of bias give two peaks in the certain voltage range at low frequencies. These observations indicate that at low frequencies, the charges at interface states can easily follow an AC signal and the number of them increases with decreasing frequency. The I-V, C-V and G/{omega}-V characteristics of the MIS structure are affected not only with R {sub s} but also N {sub ss}. Experimental results show that both the R{sub s} and C{sub o} values should be taken into account in determining frequency-dependent electrical characteristics.

A new relational database structure and online interface for the HITRAN database

Science.gov (United States)

Hill, Christian; Gordon, Iouli E.; Rothman, Laurence S.; Tennyson, Jonathan

2013-11-01

A new format for the HITRAN database is proposed. By storing the line-transition data in a number of linked tables described by a relational database schema, it is possible to overcome the limitations of the existing format, which have become increasingly apparent over the last few years as new and more varied data are being used by radiative-transfer models. Although the database in the new format can be searched using the well-established Structured Query Language (SQL), a web service, HITRANonline, has been deployed to allow users to make most common queries of the database using a graphical user interface in a web page. The advantages of the relational form of the database to ensuring data integrity and consistency are explored, and the compatibility of the online interface with the emerging standards of the Virtual Atomic and Molecular Data Centre (VAMDC) project is discussed. In particular, the ability to access HITRAN data using a standard query language from other websites, command line tools and from within computer programs is described.

Elastic waves at periodically-structured surfaces and interfaces of solids

Directory of Open Access Journals (Sweden)

A. G. Every

2014-12-01

Full Text Available This paper presents a simple treatment of elastic wave scattering at periodically structured surfaces and interfaces of solids, and the existence and nature of surface acoustic waves (SAW and interfacial (IW waves at such structures. Our treatment is embodied in phenomenological models in which the periodicity resides in the boundary conditions. These yield zone folding and band gaps at the boundary of, and within the Brillouin zone. Above the transverse bulk wave threshold, there occur leaky or pseudo-SAW and pseudo-IW, which are attenuated via radiation into the bulk wave continuum. These have a pronounced effect on the transmission and reflection of bulk waves. We provide examples of pseudo-SAW and pseudo-IW for which the coupling to the bulk wave continuum vanishes at isloated points in the dispersion relation. These supersonic guided waves correspond to embedded discrete eigenvalues within a radiation continuum. We stress the generality of the phenomena that are exhibited at widely different scales of length and frequency, and their relevance to situations as diverse as the guiding of seismic waves in mine stopes, the metrology of periodic metal interconnect structures in the semiconductor industry, and elastic wave scattering by an array of coplanar cracks in a solid.

Surface and interface characterization of thin-film silicon solar cell structures

Energy Technology Data Exchange (ETDEWEB)

Gerlach, Dominic

2013-02-21

our Si L{sub 2,3} XES analysis. Spatially resolved x-ray photoelectron spectroscopy data support this and even suggest the formation of sub-oxides or zinc silicate as an interface species. The electronic structure of the buried a-SiO{sub x}:H(B)/ZnO:Al and {mu}c-Si:H(B)/ZnO:Al interfaces are unraveled with ''depth resolved'' hard x-ray photoelectron spectroscopy. A surface band bending limited to the very surface of the silicon layers is found. The valence band maxima for the Si cover layers and the ZnO:Al TCO are determined and interface induced band bending for both interfaces are derived. At the a-SiO{sub x}:H(B)/ZnO:Al interface a tunnel barrier of (0.22 {+-} 0.31) eV and at {mu}c-Si:H(B)/ZnO:Al interface a tunnel barrier of (-0.08 {+-} 0.31) eV is determined. This explains a previously empirically found solar cell efficiency increase produced by introducing a {mu}c-Si:H(B) buffer layer between an a-Si p-i-n cell and the ZnO:Al/glass substrate.

First-principles investigation of the effect of oxidation on the electronic structure and magnetic properties at the FeRh/MgO (0 0 1) interface

Energy Technology Data Exchange (ETDEWEB)

Sakhraoui, T., E-mail: tsakhrawi@yahoo.com [Laboratoire de la Matière Condensée et des Nanosciences, Département de Physique, Faculté des Sciences de Monastir, 5019 Monastir (Tunisia); Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg (France); Said, M. [Laboratoire de la Matière Condensée et des Nanosciences, Département de Physique, Faculté des Sciences de Monastir, 5019 Monastir (Tunisia); Alouani, M. [Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg (France)

2017-06-15

Highlights: • Density functional theory is used to study the interface between the FeRh alloy and MgO. • We focus on the effect of the oxidation on the electronic structure and magnetic properties of the FeRh/MgO (0 0 1) interface. • We show the change on the structure of the Fe-d states. • We examine the charge transfer and the local spin density modification after interface oxidation. - Abstract: The effect of interfacial oxidation on electronic structure and magnetic properties at the FeRh/MgO (0 0 1) interface is studied by ab initio methods. The results show the formation of an interfacial FeO-like layer between the FeRh and the MgO barrier, which has a direct impact on Fe e{sub g} states at the interface. It is shown that these e{sub g} states are more affected than that the t{sub 2g} states at the Fermi level due to the strong hybridization of these states with the p-states of oxygen. Thus, the oxidation modifies crucially the electronic structure and the magnetic properties as compared to those of an ideal interface. In particular, it was found that spin polarization of the ferromagnetic state is substantially enhanced. A simple two-current Julliere model shows that the TMR increases with oxidation.

Chemical and structural analysis of the bone-implant interface by TOF-SIMS, SEM, FIB and TEM: Experimental study in animal

International Nuclear Information System (INIS)

Palmquist, Anders; Emanuelsson, Lena; Sjövall, Peter

2012-01-01

Although bone-anchored implants are widely used in reconstructive medicine, the mechanism of osseointegration is still not fully understood. Novel analytical tools are needed to further understand this process, where both the chemical and structural aspects of the bone-implant interface are important. The aim of this study was to evaluate the advantages of combining time-of-flight secondary ion mass spectroscopy (TOF-SIMS) with optical (LM), scanning (SEM) and transmission electron microscopy (TEM) techniques for studying the bone-implant interface of bone-anchored implants. Laser-modified titanium implants with surrounded bone retrieved after 8 weeks healing in rabbit were dehydrated and resin embedded. Three types of sample preparation were studied to evaluate the information gained by combining TOF-SIMS, SEM, FIB and TEM. The results show that imaging TOF-SIMS can provide detailed chemical information, which in combination with structural information from microscopy methods provide a more complete characterization of anatomical structures at the bone-implant interface. By investigating various sample preparation techniques, it is shown that grinded cross section samples can be used for chemical imaging using TOF-SIMS, if careful consideration of potential preparation artifacts is taken into account. TOF-SIMS analysis of FIB-prepared bone/implant cross section samples show distinct areas corresponding to bone tissue and implant with a sharp interface, although without chemical information about the organic components.

Soft Interfaces

International Nuclear Information System (INIS)

Strzalkowski, Ireneusz

1997-01-01

This book presents an extended form of the 1994 Dirac Memorial Lecture delivered by Pierre Gilles de Gennes at Cambridge University. The main task of the presentation is to show the beauty and richness of structural forms and phenomena which are observed at soft interfaces between two media. They are much more complex than forms and phenomena existing in each phase separately. Problems are discussed including both traditional, classical techniques, such as the contact angle in static and dynamic partial wetting, as well as the latest research methodology, like 'environmental' scanning electron microscopes. The book is not a systematic lecture on phenomena but it can be considered as a compact set of essays on topics which particularly fascinate the author. The continuum theory widely used in the book is based on a deep molecular approach. The author is particularly interested in a broad-minded rheology of liquid systems at interfaces with specific emphasis on polymer melts. To study this, the author has developed a special methodology called anemometry near walls. The second main topic presented in the book is the problem of adhesion. Molecular processes, energy transformations and electrostatic interaction are included in an interesting discussion of the many aspects of the principles of adhesion. The third topic concerns welding between two polymer surfaces, such as A/A and A/B interfaces. Of great worth is the presentation of various unsolved, open problems. The kind of topics and brevity of description indicate that this book is intended for a well prepared reader. However, for any reader it will present an interesting picture of how many mysterious processes are acting in the surrounding world and how these phenomena are perceived by a Nobel Laureate, who won that prize mainly for his investigations in this field. (book review)

Structure ignition assessment model (SIAM)\\t

Science.gov (United States)

Jack D. Cohen

1995-01-01

Major wildland/urban interface fire losses, principally residences, continue to occur. Although the problem is not new, the specific mechanisms are not well known on how structures ignite in association with wildland fires. In response to the need for a better understanding of wildland/urban interface ignition mechanisms and a method of assessing the ignition risk,...

The atomic structure of the Si(111)-Pb buried interface grown on the Si(111)-(#sq root#3 x #sq root#3)-Pb reconstruction

DEFF Research Database (Denmark)

Howes, P.B.; Edwards, K.A.; Macdonald, J.E.

1998-01-01

that there are structural differences between the buried interfaces. We present surface X-ray diffraction measurements of the interface grown from the incommensurate Si(111)-(root 3 x root 3)-R30 degrees-Pb reconstruction and show that, in contrast to the starting surface, the interface comprises the junction between...

Positron annihilation studies of the AlOx/SiO2/Si interface in solar cell structures

International Nuclear Information System (INIS)

Edwardson, C. J.; Coleman, P. G.; Li, T.-T. A.; Cuevas, A.; Ruffell, S.

2012-01-01

Film and film/substrate interface characteristics of 30 and 60 nm-thick AlO x films grown on Si substrates by thermal atomic layer deposition (ALD), and 30 nm-thick AlO x films by sputtering, have been probed using variable-energy positron annihilation spectroscopy (VEPAS) and Doppler-broadened spectra ratio curves. All samples were found to have an interface which traps positrons, with annealing increasing this trapping response, regardless of growth method. Thermal ALD creates an AlO x /SiO x /Si interface with positron trapping and annihilation occurring in the Si side of the SiO x /Si boundary. An induced positive charge in the Si next to the interface reduces diffusion into the oxides and increases annihilation in the Si. In this region there is a divacancy-type response (20 ± 2%) before annealing which is increased to 47 ± 2% after annealing. Sputtering seems to not produce samples with this same electrostatic shielding; instead, positron trapping occurs directly in the SiO x interface in the as-deposited sample, and the positron response to it increases after annealing as an SiO 2 layer is formed. Annealing the film has the effect of lowering the film oxygen response in all film types. Compared to other structural characterization techniques, VEPAS shows larger sensitivity to differences in film preparation method and between as-deposited and annealed samples.

The computer graphics interface

CERN Document Server

Steinbrugge Chauveau, Karla; Niles Reed, Theodore; Shepherd, B

2014-01-01

The Computer Graphics Interface provides a concise discussion of computer graphics interface (CGI) standards. The title is comprised of seven chapters that cover the concepts of the CGI standard. Figures and examples are also included. The first chapter provides a general overview of CGI; this chapter covers graphics standards, functional specifications, and syntactic interfaces. Next, the book discusses the basic concepts of CGI, such as inquiry, profiles, and registration. The third chapter covers the CGI concepts and functions, while the fourth chapter deals with the concept of graphic obje

Interface colloidal robotic manipulator

Science.gov (United States)

Aronson, Igor; Snezhko, Oleksiy

2015-08-04

A magnetic colloidal system confined at the interface between two immiscible liquids and energized by an alternating magnetic field dynamically self-assembles into localized asters and arrays of asters. The colloidal system exhibits locomotion and shape change. By controlling a small external magnetic field applied parallel to the interface, structures can capture, transport, and position target particles.

LoopX: A Graphical User Interface-Based Database for Comprehensive Analysis and Comparative Evaluation of Loops from Protein Structures.

Science.gov (United States)

Kadumuri, Rajashekar Varma; Vadrevu, Ramakrishna

2017-10-01

Due to their crucial role in function, folding, and stability, protein loops are being targeted for grafting/designing to create novel or alter existing functionality and improve stability and foldability. With a view to facilitate a thorough analysis and effectual search options for extracting and comparing loops for sequence and structural compatibility, we developed, LoopX a comprehensively compiled library of sequence and conformational features of ∼700,000 loops from protein structures. The database equipped with a graphical user interface is empowered with diverse query tools and search algorithms, with various rendering options to visualize the sequence- and structural-level information along with hydrogen bonding patterns, backbone φ, ψ dihedral angles of both the target and candidate loops. Two new features (i) conservation of the polar/nonpolar environment and (ii) conservation of sequence and conformation of specific residues within the loops have also been incorporated in the search and retrieval of compatible loops for a chosen target loop. Thus, the LoopX server not only serves as a database and visualization tool for sequence and structural analysis of protein loops but also aids in extracting and comparing candidate loops for a given target loop based on user-defined search options.

Buried interfaces - A systematic study to characterize an adhesive interface at multiple scales

Science.gov (United States)

Haubrich, Jan; Löbbecke, Miriam; Watermeyer, Philipp; Wilde, Fabian; Requena, Guillermo; da Silva, Julio

2018-03-01

A comparative study of a model adhesive interface formed between laser-pretreated Ti15-3-3-3 and the thermoplastic polymer PEEK has been carried out in order to characterize the interfaces' structural details and the infiltration of the surface nano-oxide by the polymer at multiple scales. Destructive approaches such as scanning and transmission electron microscopy of microsections prepared by focused ion beam, and non-destructive imaging approaches including laser scanning and scanning electron microscopy of pretreated surfaces as well as synchrotron computed tomography techniques (micro- and ptychographic tomographies) were employed for resolving the large, μm-sized melt-structures and the fine nano-oxide substructure within the buried interface. Scanning electron microscopy showed that the fine, open-porous nano-oxide homogeneously covers the larger macrostructure features which in turn cover the joint surface. The open-porous nano-oxide forming the interface itself appears to be fully infiltrated and wetted by the polymer. No voids or even channels were detected down to the respective resolution limits of scanning and transmission electron microscopy.

Secondary structure of spiralin in solution, at the air/water interface, and in interaction with lipid monolayers.

Science.gov (United States)

Castano, Sabine; Blaudez, Daniel; Desbat, Bernard; Dufourcq, Jean; Wróblewski, Henri

2002-05-03

The surface of spiroplasmas, helically shaped pathogenic bacteria related to the mycoplasmas, is crowded with the membrane-anchored lipoprotein spiralin whose structure and function are unknown. In this work, the secondary structure of spiralin under the form of detergent-free micelles (average Stokes radius, 87.5 A) in water and at the air/water interface, alone or in interaction with lipid monolayers was analyzed. FT-IR and circular dichroism (CD) spectroscopic data indicate that spiralin in solution contains about 25+/-3% of helices and 38+/-2% of beta sheets. These measurements are consistent with a consensus predictive analysis of the protein sequence suggesting about 28% of helices, 32% of beta sheets and 40% of irregular structure. Brewster angle microscopy (BAM) revealed that, in water, the micelles slowly disaggregate to form a stable and homogeneous layer at the air/water interface, exhibiting a surface pressure up to 10 mN/m. Polarization modulation infrared reflection absorption spectroscopy (PMIRRAS) spectra of interfacial spiralin display a complex amide I band characteristic of a mixture of beta sheets and alpha helices, and an intense amide II band. Spectral simulations indicate a flat orientation for the beta sheets and a vertical orientation for the alpha helices with respect to the interface. The combination of tensiometric and PMIRRAS measurements show that, when spiroplasma lipids are used to form a monolayer at the air/water interface, spiralin is adsorbed under this monolayer and its antiparallel beta sheets are mainly parallel to the polar-head layer of the lipids without deep perturbation of the fatty acid chains organization. Based upon these results, we propose a 'carpet model' for spiralin organization at the spiroplasma cell surface. In this model, spiralin molecules anchored into the outer leaflet of the lipid bilayer by their N-terminal lipid moiety are composed of two colinear domains (instead of a single globular domain) situated at

Influence of surface chemistry on the structural organization of monomolecular protein layers adsorbed to functionalized aqueous interfaces

DEFF Research Database (Denmark)

Lösche, M.; Piepenstock, M.; Diederich, A.

1993-01-01

The molecular organization of streptavidin (SA) bound to aqueous surface monolayers of biotin-functionalized lipids and binary lipid mixtures has been investigated with neutron reflectivity and electron and fluorescence microscopy. The substitution of deuterons (2H) for protons (1H), both...... in subphase water molecules and in the alkyl chains of the lipid surface monolayer, was utilized to determine the interface structure on the molecular length scale. In all cases studied, the protein forms monomolecular layers underneath the interface with thickness values of apprx 40 ANG . A systematic...... dependence of the structural properties of such self-assembled SA monolayers on the surface chemistry was observed: the lateral protein density depends on the length of the spacer connecting the biotin moiety and its hydrophobic anchor. The hydration of the lipid head groups in the protein-bound state...

Classification of user interfaces for graph-based online analytical processing

Science.gov (United States)

Michaelis, James R.

2016-05-01

In the domain of business intelligence, user-oriented software for conducting multidimensional analysis via Online- Analytical Processing (OLAP) is now commonplace. In this setting, datasets commonly have well-defined sets of dimensions and measures around which analysis tasks can be conducted. However, many forms of data used in intelligence operations - deriving from social networks, online communications, and text corpora - will consist of graphs with varying forms of potential dimensional structure. Hence, enabling OLAP over such data collections requires explicit definition and extraction of supporting dimensions and measures. Further, as Graph OLAP remains an emerging technique, limited research has been done on its user interface requirements. Namely, on effective pairing of interface designs to different types of graph-derived dimensions and measures. This paper presents a novel technique for pairing of user interface designs to Graph OLAP datasets, rooted in Analytic Hierarchy Process (AHP) driven comparisons. Attributes of the classification strategy are encoded through an AHP ontology, developed in our alternate work and extended to support pairwise comparison of interfaces. Specifically, according to their ability, as perceived by Subject Matter Experts, to support dimensions and measures corresponding to Graph OLAP dataset attributes. To frame this discussion, a survey is provided both on existing variations of Graph OLAP, as well as existing interface designs previously applied in multidimensional analysis settings. Following this, a review of our AHP ontology is provided, along with a listing of corresponding dataset and interface attributes applicable toward SME recommendation structuring. A walkthrough of AHP-based recommendation encoding via the ontology-based approach is then provided. The paper concludes with a short summary of proposed future directions seen as essential for this research area.

Computer Program Development Specification for Tactical Interface System.

Science.gov (United States)

1981-07-31

CNTL CNTL TO ONE VT~i.AE CR1 & TWELVE VT100 LCARD READER VIDEO TERMINALS, SIX LA12O) HARD- COPY TERMINALS, & VECTOR GRAPHICS RPO % TERMINAL 17%M DISK...this data into the TIS para - .. meter tables in the TISGBL common area. ICEHANDL will send test interface ICE to PSS in one of two modes: perio- dically...STOPCauss te TI sotwar toexit ,9.*9~ .r .~ * ~%.’h .9~ .. a .~ .. a. 1 , , p * % .’.-:. .m 7 P : SDSS-MMP-BI ." 31 July 1981 TCL commands authorized

Interface properties of 4H-SiC MOS structures studied by a slow positron beam

International Nuclear Information System (INIS)

Maekawa, M.; Kawasuso, A.; Ichimiya, A.; Yoshikawa, M.

2004-01-01

Interfacial defects existing near the SiO 2 /SiC interface are an important issue for fabrication of high performance SiC devices. We investigate a thermally grown SiO 2 /SiC layer of 4H-SiC MOS structure by positron annihilation spectroscopy. The Doppler broadening of annihilation quanta was measured as a function of the incident positron energy and the gate bias. Applying a negative gate bias, significant increases in S-parameters were observed. This indicates the migration of implanted positrons towards the SiO 2 /SiC interface and annihilation at interfacial defects. Ultraviolet (UV) ray irradiation was used to extract the influence of the positron trapping to the interfacial states. S-parameters in the interface region were reduced by UV irradiation. This shows that positron trapping probability decreased because the charge state of interfacial defects changed to positive. From the recovery of S-parameters after 24 hours, the interfacial states discharge slowly and exist in large quantities, because the changes of S-parameter by the UV irradiation are larger than changes induced by bias change. (orig.)

Deducing 2D Crystal Structure at the Solid/Liquid Interface with Atomic Resolution by Combined STM and SFG Study

Science.gov (United States)

McClelland, Arthur; Ahn, Seokhoon; Matzger, Adam J.; Chen, Zhan

2009-03-01

Supplemented by computed models, Scanning Tunneling Microscopy (STM) can provide detailed structure of 2D crystals formed at the liquid/solid interface with atomic resolution. However, some structural information such as functional group orientations in such 2D crystals needs to be tested experimentally to ensure the accuracy of the deduced structures. Due to the limited sensitivity, many other experimental techniques such as Raman and infrared spectroscopy have not been allowed to provide such structural information of 2D crystals. Here we showed that Sum Frequency Generation Vibrational Spectroscopy (SFG) can measure average orientation of functional groups in such 2D crystals, or physisorbed monolayers, providing key experimental data to aid in the modeling and interpretation of the STM images. The usefulness of combining these two techniques is demonstrated with a phthalate diesters monolayer formed at the 1-phenyloctane/ highly oriented pyrolytic graphite (HOPG) interface. The spatial orientation of the ester C=O of the monolayer was successfully determined using SFG.

Atomic structures and compositions of internal interfaces. Progress report, September 1, 1991--August 31, 1992

Energy Technology Data Exchange (ETDEWEB)

Seidman, D.N. [Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering; Merkle, K.L. [Argonne National Lab., IL (United States)

1992-03-01

This research program addresses fundamental questions concerning the relationships between atomic structures and chemical compositions of metal/ceramic heterophase interfaces. The chemical composition profile across a Cu/MgO {l_brace}111{r_brace}-type heterophase interface, produced by the internal oxidation of a Cu(Mg) single phase alloy, is measured via atom-probe field-ion microscopy with a spatial resolution of 0.121 nm; this resolution is equal to the interplanar space of the {l_brace}222{r_brace} MgO planes. In particular, we demonstrate for the first time that the bonding across a Cu/MgO {l_brace}111{r_brace}-type heterophase interface, along a <111> direction common to both the Cu matrix and an MgO precipitate, has the sequence Cu{vert_bar}O{vert_bar}Mg{hor_ellipsis} and not Cu{vert_bar}Mg{vert_bar}O{hor_ellipsis}; this result is achieved without any deconvolution of the experimental data. Before determining this chemical sequence it was established, via high resolution electron microscopy, that the morphology of an MgO precipitate in a Cu matrix is an octahedron faceted on {l_brace}111{r_brace} planes with a cube-on-cube relationship between a precipitate and the matrix. First results are also presented for the Ni/Cr{sub 2}O{sub 4} interface; for this system selected area atom probe microscopy was used to analyze this interface; Cr{sub 2}O{sub 4} precipitates are located in a field-ion microscope tip and a precipitate is brought into the tip region via a highly controlled electropolishing technique.

Demonstrating the feasibility of monitoring the molecular-level structures of moving polymer/silane interfaces during silane diffusion using SFG.

Science.gov (United States)

Chen, Chunyan; Wang, Jie; Loch, Cheryl L; Ahn, Dongchan; Chen, Zhan

2004-02-04

In this paper, the feasibility of monitoring molecular structures at a moving polymer/liquid interface by sum frequency generation (SFG) vibrational spectroscopy has been demonstrated. N-(2-Aminoethyl)-3-aminopropyltrimethoxysilane (AATM, NH2(CH2)2NH(CH2)3Si(OCH3)3) has been brought into contact with a deuterated poly(methyl methacrylate) (d-PMMA) film, and the interfacial silane structure has been monitored using SFG. Upon initial contact, the SFG spectra can be detected, but as time progresses, the spectral intensity changes and finally disappears. Additional experiments indicate that these silane molecules can diffuse into the polymer film and the detected SFG signals are actually from the moving polymer/silane interface. Our results show that the molecular order of the polymer/silane interface exists during the entire diffusion process and is lost when the silane molecules traverse through the thickness of the d-PMMA film. The loss of the SFG signal is due to the formation of a new disordered substrate/silane interface, which contributes no detectable SFG signal. The kinetics of the diffusion of the silane into the polymer have been deduced from the time-dependent SFG signals detected from the AATM molecules as they diffuse through polymer films of different thickness.

Protein-protein interface detection using the energy centrality relationship (ECR characteristic of proteins.

Directory of Open Access Journals (Sweden)

Sanjana Sudarshan

Full Text Available Specific protein interactions are responsible for most biological functions. Distinguishing Functionally Linked Interfaces of Proteins (FLIPs, from Functionally uncorrelated Contacts (FunCs, is therefore important to characterizing these interactions. To achieve this goal, we have created a database of protein structures called FLIPdb, containing proteins belonging to various functional sub-categories. Here, we use geometric features coupled with Kortemme and Baker's computational alanine scanning method to calculate the energetic sensitivity of each amino acid at the interface to substitution, identify hotspots, and identify other factors that may contribute towards an interface being FLIP or FunC. Using Principal Component Analysis and K-means clustering on a training set of 160 interfaces, we could distinguish FLIPs from FunCs with an accuracy of 76%. When these methods were applied to two test sets of 18 and 170 interfaces, we achieved similar accuracies of 78% and 80%. We have identified that FLIP interfaces have a stronger central organizing tendency than FunCs, due, we suggest, to greater specificity. We also observe that certain functional sub-categories, such as enzymes, antibody-heavy-light, antibody-antigen, and enzyme-inhibitors form distinct sub-clusters. The antibody-antigen and enzyme-inhibitors interfaces have patterns of physical characteristics similar to those of FunCs, which is in agreement with the fact that the selection pressures of these interfaces is differently evolutionarily driven. As such, our ECR model also successfully describes the impact of evolution and natural selection on protein-protein interfaces. Finally, we indicate how our ECR method may be of use in reducing the false positive rate of docking calculations.

Surface and interface effects in VLSI

CERN Document Server

Einspruch, Norman G

1985-01-01

VLSI Electronics Microstructure Science, Volume 10: Surface and Interface Effects in VLSI provides the advances made in the science of semiconductor surface and interface as they relate to electronics. This volume aims to provide a better understanding and control of surface and interface related properties. The book begins with an introductory chapter on the intimate link between interfaces and devices. The book is then divided into two parts. The first part covers the chemical and geometric structures of prototypical VLSI interfaces. Subjects detailed include, the technologically most import

A comparative study about electronic structures at rubrene/Ag and Ag/rubrene interfaces

Directory of Open Access Journals (Sweden)

Sumona Sinha

2015-10-01

Full Text Available The contact between the electrode and the organic semiconductor is one of the most crucial factors in determining the organic device performance. The development and production technology of different organic devices require the understanding of different types of metal/organic semiconducting thin film interfaces. Comparisons about the electronic structures at Rubrene/Ag and Ag/Rubrene interfaces have been studied using photoemission spectroscopy. The Ag on rubrene interfaces is found to show more interesting and complex natures than its counterpart. The vacuum level (VL was shifted about 0.51 eV from push back effect for deposition of 5 Å rubrene onto Ag film whereas the electronic features of silver was only suppressed and no energy shift was resulted. While the deposition of 5 Å Ag onto rubrene film leads to the diffusion of the Ag atoms, as a cluster with quantum size effect, inside the film. Angle dependent XPS measurement indicates that diffused metal clusters were present at entire probed depth of the film. Moreover these clusters dope the uppermost surface of the rubrene film which consequences a shift of the electronic states of thick organic film towards higher binding energy. The VL was found to shift about 0.31 eV toward higher binding energy whereas the shift was around 0.21 eV for the electronic states of rubrene layer.

A comparative study about electronic structures at rubrene/Ag and Ag/rubrene interfaces

Energy Technology Data Exchange (ETDEWEB)

Sinha, Sumona, E-mail: sumona.net.09@gmail.com; Mukherjee, M. [Saha Institute of Nuclear Physics, 1/AF, Bidhan Nagar, Kolkata 700064 (India)

2015-10-15

The contact between the electrode and the organic semiconductor is one of the most crucial factors in determining the organic device performance. The development and production technology of different organic devices require the understanding of different types of metal/organic semiconducting thin film interfaces. Comparisons about the electronic structures at Rubrene/Ag and Ag/Rubrene interfaces have been studied using photoemission spectroscopy. The Ag on rubrene interfaces is found to show more interesting and complex natures than its counterpart. The vacuum level (VL) was shifted about 0.51 eV from push back effect for deposition of 5 Å rubrene onto Ag film whereas the electronic features of silver was only suppressed and no energy shift was resulted. While the deposition of 5 Å Ag onto rubrene film leads to the diffusion of the Ag atoms, as a cluster with quantum size effect, inside the film. Angle dependent XPS measurement indicates that diffused metal clusters were present at entire probed depth of the film. Moreover these clusters dope the uppermost surface of the rubrene film which consequences a shift of the electronic states of thick organic film towards higher binding energy. The VL was found to shift about 0.31 eV toward higher binding energy whereas the shift was around 0.21 eV for the electronic states of rubrene layer.

User interface design considerations

DEFF Research Database (Denmark)

Andersen, Simon Engedal; Jakobsen, Arne; Rasmussen, Bjarne D.

1999-01-01

and output variables. This feature requires special attention when designing the user interface and a special approach for controlling the user selection of input and output variables are developed. To obtain a consistent system description the different input variables are grouped corresponding......When designing a user interface for a simulation model there are several important issues to consider: Who is the target user group, and which a priori information can be expected. What questions do the users want answers to and what questions are answered using a specific model?When developing...... the user interface of EESCoolTools these issues led to a series of simulation tools each with a specific purpose and a carefully selected set of input and output variables. To allow a more wide range of questions to be answered by the same model, the user can change between different sets of input...

Using SNOMED CT to represent two interface terminologies.

Science.gov (United States)

Rosenbloom, S Trent; Brown, Steven H; Froehling, David; Bauer, Brent A; Wahner-Roedler, Dietlind L; Gregg, William M; Elkin, Peter L

2009-01-01

Interface terminologies are designed to support interactions between humans and structured medical information. In particular, many interface terminologies have been developed for structured computer based documentation systems. Experts and policy-makers have recommended that interface terminologies be mapped to reference terminologies. The goal of the current study was to evaluate how well the reference terminology SNOMED CT could map to and represent two interface terminologies, MEDCIN and the Categorical Health Information Structured Lexicon (CHISL). Automated mappings between SNOMED CT and 500 terms from each of the two interface terminologies were evaluated by human reviewers, who also searched SNOMED CT to identify better mappings when this was judged to be necessary. Reviewers judged whether they believed the interface terms to be clinically appropriate, whether the terms were covered by SNOMED CT concepts and whether the terms' implied semantic structure could be represented by SNOMED CT. Outcomes included concept coverage by SNOMED CT for study terms and their implied semantics. Agreement statistics and compositionality measures were calculated. The SNOMED CT terminology contained concepts to represent 92.4% of MEDCIN and 95.9% of CHISL terms. Semantic structures implied by study terms were less well covered, with some complex compositional expressions requiring semantics not present in SNOMED CT. Among sampled terms, those from MEDCIN were more complex than those from CHISL, containing an average 3.8 versus 1.8 atomic concepts respectively, pterms.

Low energy electron diffraction (LEED) and sum frequency generation (SFG) vibrational spectroscopy studies of solid-vacuum, solid-air and solid-liquid interfaces

Energy Technology Data Exchange (ETDEWEB)

Hoffer, Saskia [Univ. of California, Berkeley, CA (United States)

2002-01-01

Electron based surface probing techniques can provide detailed information about surface structure or chemical composition in vacuum environments. The development of new surface techniques has made possible in situ molecular level studies of solid-gas interfaces and more recently, solid-liquid interfaces. The aim of this dissertation is two-fold. First, by using novel sample preparation, Low Energy Electron Diffraction (LEED) and other traditional ultra high vacuum (UHV) techniques are shown to provide new information on the insulator/vacuum interface. The surface structure of the classic insulator NaCl has been determined using these methods. Second, using sum frequency generation (SFG) surface specific vibrational spectroscopy studies were performed on both the biopolymer/air and electrode/electrolyte interfaces. The surface structure and composition of polyetherurethane-silicone copolymers were determined in air using SFG, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). SFG studies of the electrode (platinum, gold and copper)/electrolyte interface were performed as a function of applied potential in an electrochemical cell.

Protein-RNA interface residue prediction using machine learning: an assessment of the state of the art.

Science.gov (United States)

Walia, Rasna R; Caragea, Cornelia; Lewis, Benjamin A; Towfic, Fadi; Terribilini, Michael; El-Manzalawy, Yasser; Dobbs, Drena; Honavar, Vasant

2012-05-10

RNA molecules play diverse functional and structural roles in cells. They function as messengers for transferring genetic information from DNA to proteins, as the primary genetic material in many viruses, as catalysts (ribozymes) important for protein synthesis and RNA processing, and as essential and ubiquitous regulators of gene expression in living organisms. Many of these functions depend on precisely orchestrated interactions between RNA molecules and specific proteins in cells. Understanding the molecular mechanisms by which proteins recognize and bind RNA is essential for comprehending the functional implications of these interactions, but the recognition 'code' that mediates interactions between proteins and RNA is not yet understood. Success in deciphering this code would dramatically impact the development of new therapeutic strategies for intervening in devastating diseases such as AIDS and cancer. Because of the high cost of experimental determination of protein-RNA interfaces, there is an increasing reliance on statistical machine learning methods for training predictors of RNA-binding residues in proteins. However, because of differences in the choice of datasets, performance measures, and data representations used, it has been difficult to obtain an accurate assessment of the current state of the art in protein-RNA interface prediction. We provide a review of published approaches for predicting RNA-binding residues in proteins and a systematic comparison and critical assessment of protein-RNA interface residue predictors trained using these approaches on three carefully curated non-redundant datasets. We directly compare two widely used machine learning algorithms (Naïve Bayes (NB) and Support Vector Machine (SVM)) using three different data representations in which features are encoded using either sequence- or structure-based windows. Our results show that (i) Sequence-based classifiers that use a position-specific scoring matrix (PSSM

Workshops of the Sixth International Brain–Computer Interface Meeting : brain–computer interfaces past, present, and future

NARCIS (Netherlands)

Huggins, Jane E.; Guger, Christoph; Ziat, Mounia; Zander, Thorsten O.; Taylor, Denise; Tangermann, Michael; Soria-Frisch, Aureli; Simeral, John; Scherer, Reinhold; Rupp, Rüdiger; Ruffini, Giulio; Robinson, Douglas K.R.; Ramsey, Nick F.; Nijholt, Anton; Müller-Putz, Gernot R.; McFarland, Dennis J.; Mattia, Donatella; Lance, Brent J.; Kindermans, Pieter-Jan; Iturrate, Iñaki; Herff, Christian; Gupta, Disha; Do, An H.; Collinger, Jennifer L.; Chavarriaga, Ricardo; Chasey, Steven M.; Bleichner, Martin G.; Batista, Aaron; Anderson, Charles W.; Aarnoutse, Erik J.

2017-01-01

The Sixth International Brain–Computer Interface (BCI) Meeting was held 30 May–3 June 2016 at the Asilomar Conference Grounds, Pacific Grove, California, USA. The conference included 28 workshops covering topics in BCI and brain–machine interface research. Topics included BCI for specific

Heuristicas para avaliacao de interfaces de portais universitarios

NARCIS (Netherlands)

Pelogi, A.P.S.; van Amstel, Frederick; Barsottini, C.G.N.

2012-01-01

The Heuristic Evaluation method seems to be efficient to diagnose interface usability problems. The propose at this study is to determine whether specific heuristics for university portals are appropriate and contribute to a more specific evaluation of interface usability of the portal of the

Oxide nanoparticles in an Al-alloyed oxide dispersion strengthened steel: crystallographic structure and interface with ferrite matrix

DEFF Research Database (Denmark)

Zhang, Zhenbo; Pantleon, Wolfgang

2017-01-01

Oxide nanoparticles are quintessential for ensuring the extraordinary properties of oxide dispersion strengthened (ODS) steels. In this study, the crystallographic structure of oxide nanoparticles, and their interface with the ferritic steel matrix in an Al-alloyed ODS steel, i.e. PM2000, were...

Impact of biogenic amine molecular weight and structure on surfactant adsorption at the air-water interface.

Science.gov (United States)

Penfold, Jeffrey; Thomas, Robert K; Li, Peixun

2016-02-01

The oligoamines, such as ethylenediamine to pentaethylenetetramine, and the aliphatic biogenic amines, such as putrescine, spermidine and spermine, strongly interact with anionic surfactants, such as sodium dodecylsulfate, SDS. It has been shown that this results in pronounced surfactant adsorption at the air-water interface and the transition from monolayer to multilayer adsorption which depends upon solution pH and oligoamine structure. In the neutron reflectivity, NR, and surface tension, ST, results presented here the role of the oligoamine structure on the adsorption of SDS is investigated more fully using a range of different biogenic amines. The effect of the extent of the intra-molecular spacing between amine groups on the adsorption has been extended by comparing results for cadavarine with putrescine and ethylenediamine. The impact of more complex biogenic amine structures on the adsorption has been investigated with the aromatic phenethylamine, and the heterocyclic amines histamine and melamine. The results provide an important insight into how surfactant adsorption at interfaces can be manipulated by the addition of biogenic amines, and into the role of solution pH and oligoamine structure in modifying the interaction between the surfactant and oligoamine. The results impact greatly upon potential applications and in understanding some of the important biological functions of biogenic amines. Copyright © 2015 Elsevier Inc. All rights reserved.

Standard interfaces for program-modular multiprocessor systems

International Nuclear Information System (INIS)

Chernykh, E.V.

1982-01-01

The peculiarities of the structures of existing and developed standard interfaces used in automation systems for nuclear physical experiments are considered. general structural characteristics of multiprocessor system interfaces are revealed. The comparison of the existing system CAMAC crate and designed standards of COMPEX, E3S and FASTBUS interfaces by capacity and relative cost is carried out. The analysis of the given data shows that operation of any interface is more advantageous at the rates close to capacity values, the relative cost being minimum. In this case the advantage is on the side of interfaces with greater capacity values for which at a moderated decrease of the exchange or requests processing rate the relative costs grow slower. A higher capacity of one-cycle exchange is provided with functional data way specialization in the interface. The conclusion is drawn that most perspective trend in the development of automation systems for high energy physics experiments is using FASTBUS standard

Designing end-user interfaces

CERN Document Server

Heaton, N

1988-01-01

Designing End-User Interfaces: State of the Art Report focuses on the field of human/computer interaction (HCI) that reviews the design of end-user interfaces.This compilation is divided into two parts. Part I examines specific aspects of the problem in HCI that range from basic definitions of the problem, evaluation of how to look at the problem domain, and fundamental work aimed at introducing human factors into all aspects of the design cycle. Part II consists of six main topics-definition of the problem, psychological and social factors, principles of interface design, computer intelligenc

Molecular Design of Branched and Binary Molecules at Ordered Interfaces

Energy Technology Data Exchange (ETDEWEB)

Genson, Kirsten Larson [Iowa State Univ., Ames, IA (United States)

2005-01-01

This study examined five different branched molecular architectures to discern the effect of design on the ability of molecules to form ordered structures at interfaces. Photochromic monodendrons formed kinked packing structures at the air-water interface due to the cross-sectional area mismatch created by varying number of alkyl tails and the hydrophilic polar head group. The lower generations formed orthorhombic unit cell with long range ordering despite the alkyl tails tilted to a large degree. Favorable interactions between liquid crystalline terminal groups and the underlying substrate were observed to compel a flexible carbosilane dendrimer core to form a compressed elliptical conformation which packed stagger within lamellae domains with limited short range ordering. A twelve arm binary star polymer was observed to form two dimensional micelles at the air-water interface attributed to the higher polystyrene block composition. Linear rod-coil molecules formed a multitude of packing structures at the air-water interface due to the varying composition. Tree-like rod-coil molecules demonstrated the ability to form one-dimensional structures at the air-water interface and at the air-solvent interface caused by the preferential ordering of the rigid rod cores. The role of molecular architecture and composition was examined and the influence chemically competing fragments was shown to exert on the packing structure. The amphiphilic balance of the different molecular series exhibited control on the ordering behavior at the air-water interface and within bulk structures. The shell nature and tail type was determined to dictate the preferential ordering structure and molecular reorganization at interfaces with the core nature effect secondary.

Rationalization and Design of the Complementarity Determining Region Sequences in an Antibody-Antigen Recognition Interface

Science.gov (United States)

Chen, Ing-Chien; Lee, Yu-Ching; Chen, Jun-Bo; Tsai, Keng-Chang; Chen, Ching-Tai; Chang, Jeng-Yih; Yang, Ei-Wen; Hsu, Po-Chiang; Jian, Jhih-Wei; Hsu, Hung-Ju; Chang, Hung-Ju; Hsu, Wen-Lian; Huang, Kai-Fa; Ma, Alex Che; Yang, An-Suei

2012-01-01

Protein-protein interactions are critical determinants in biological systems. Engineered proteins binding to specific areas on protein surfaces could lead to therapeutics or diagnostics for treating diseases in humans. But designing epitope-specific protein-protein interactions with computational atomistic interaction free energy remains a difficult challenge. Here we show that, with the antibody-VEGF (vascular endothelial growth factor) interaction as a model system, the experimentally observed amino acid preferences in the antibody-antigen interface can be rationalized with 3-dimensional distributions of interacting atoms derived from the database of protein structures. Machine learning models established on the rationalization can be generalized to design amino acid preferences in antibody-antigen interfaces, for which the experimental validations are tractable with current high throughput synthetic antibody display technologies. Leave-one-out cross validation on the benchmark system yielded the accuracy, precision, recall (sensitivity) and specificity of the overall binary predictions to be 0.69, 0.45, 0.63, and 0.71 respectively, and the overall Matthews correlation coefficient of the 20 amino acid types in the 24 interface CDR positions was 0.312. The structure-based computational antibody design methodology was further tested with other antibodies binding to VEGF. The results indicate that the methodology could provide alternatives to the current antibody technologies based on animal immune systems in engineering therapeutic and diagnostic antibodies against predetermined antigen epitopes. PMID:22457753

First-principles investigation of the structure and synergistic chemical bonding of Ag and Mg at the Al | Ω interface in a Al-Cu-Mg-Ag alloy

International Nuclear Information System (INIS)

Sun Lipeng; Irving, Douglas L.; Zikry, Mohammed A.; Brenner, D.W.

2009-01-01

Density functional theory was used to characterize the atomic structure and bonding of the Al | Ω interface in a Al-Cu-Mg-Ag alloy. The most stable interfacial structure was found to be connected by Al-Al bonds with a hexagonal Al lattice on the surface of the Ω phase sitting on the vacant hollow sites of the Al {1 1 1} matrix plane. The calculations predict that when substituted separately for Al at this interface, Ag and Mg do not enhance the interface stability through chemical bonding. Combining Ag and Mg, however, was found to chemically stabilize this interface, with the lowest-energy structure examined being a bi-layer with Ag atoms adjacent to the Al matrix and Mg adjacent to the Ω phase. This study provides an atomic arrangement for the interfacial bi-layer observed experimentally in this alloy.

Computational design of patterned interfaces using reduced order models

International Nuclear Information System (INIS)

Vattre, A.J.; Abdolrahim, N.; Kolluri, K.; Demkowicz, M.J.

2014-01-01

Patterning is a familiar approach for imparting novel functionalities to free surfaces. We extend the patterning paradigm to interfaces between crystalline solids. Many interfaces have non-uniform internal structures comprised of misfit dislocations, which in turn govern interface properties. We develop and validate a computational strategy for designing interfaces with controlled misfit dislocation patterns by tailoring interface crystallography and composition. Our approach relies on a novel method for predicting the internal structure of interfaces: rather than obtaining it from resource-intensive atomistic simulations, we compute it using an efficient reduced order model based on anisotropic elasticity theory. Moreover, our strategy incorporates interface synthesis as a constraint on the design process. As an illustration, we apply our approach to the design of interfaces with rapid, 1-D point defect diffusion. Patterned interfaces may be integrated into the microstructure of composite materials, markedly improving performance. (authors)

Determination of three-dimensional interfacial strain - A novel method of probing interface structure with X-ray Bragg-surface diffraction

International Nuclear Information System (INIS)

Sun, W.-C.; Chu, C.-H.; Chang, H.-C.; Wu, B.-K.; Chen, Y.-R.; Cheng, C.-W.; Chiu, M.-S.; Shen, Y.-C.; Wu, H.-H.; Hung, Y.-S.; Chang, S.-L.; Hong, M.-H.; Tang, M.-T.; Stetsko, Yu.P.

2007-01-01

A new X-ray diffraction technique is developed to probe structural variations at the interfaces between epitaxy thin films and single-crystal substrates. The technique utilizes three-wave Bragg-surface diffraction, where a symmetric Bragg reflection and an asymmetric surface reflection are involved. The propagation of the latter along the interfaces conveys structural information about the interfacial region between the substrate and epi-layers. The sample systems of Au/GaAs(001) are subject to the three-wave diffraction investigation using synchrotron radiation. The GaAs three-wave Bragg-surface diffractions (006)/(11-bar3) and (006)/(1-bar1-bar3), are employed. The images of the surface diffracted waves are recorded with an image plate. The obtained images show relative positions of diffraction spots near the image of the interfacial boundary, which give the variation of lattice constant along the surface normal and in-plane directions. With the aid of grazing-incidence diffraction, three-dimensional mapping of strain field at the interfaces is possible. Details about this diffraction technique and the analysis procedures are discussed

Intelligent Multi-Media Integrated Interface Project

Science.gov (United States)

1990-06-01

been devoted to the application of aritificial intelligence technology to the development of human -computer interface technology that integrates speech...RADC-TR-90-128 Final Technical Report June 1090 AD-A225 973 INTELLIGENT MULTI-MEDIA INTEGRATED INTERFACE PROJECT Calspan-University of Buffalo...contractual obligations or notices on a specific document require that it be returned. INTELLIGENT MULTI-MEDIA INTEGRATED INTERFACE PROJECT J. G. Neal J. M

Structural basis for catalysis at the membrane-water interface.

Science.gov (United States)

Dufrisne, Meagan Belcher; Petrou, Vasileios I; Clarke, Oliver B; Mancia, Filippo

2017-11-01

The membrane-water interface forms a uniquely heterogeneous and geometrically constrained environment for enzymatic catalysis. Integral membrane enzymes sample three environments - the uniformly hydrophobic interior of the membrane, the aqueous extramembrane region, and the fuzzy, amphipathic interfacial region formed by the tightly packed headgroups of the components of the lipid bilayer. Depending on the nature of the substrates and the location of the site of chemical modification, catalysis may occur in each of these environments. The availability of structural information for alpha-helical enzyme families from each of these classes, as well as several beta-barrel enzymes from the bacterial outer membrane, has allowed us to review here the different ways in which each enzyme fold has adapted to the nature of the substrates, products, and the unique environment of the membrane. Our focus here is on enzymes that process lipidic substrates. This article is part of a Special Issue entitled: Bacterial Lipids edited by Russell E. Bishop. Copyright © 2016 Elsevier B.V. All rights reserved.

Nanoengineered Interfaces, Coatings, and Structures by Plasma Techniques.

Science.gov (United States)

Vasilev, Krasimir; Ramiasa, Melanie Macgregor

2017-12-15

Nanoparticles, nanotubes, nanobelts, nanoneedles, nanosheets, nanowires, nanopillars: the variety of nanostructured interfaces that can be created and modified using plasma processes is virtually endless.[...].

Atomic Scale Structure-Chemistry Relationships at Oxide Catalyst Surfaces and Interfaces

Science.gov (United States)

McBriarty, Martin E.

Oxide catalysts are integral to chemical production, fuel refining, and the removal of environmental pollutants. However, the atomic-scale phenomena which lead to the useful reactive properties of catalyst materials are not sufficiently understood. In this work, the tools of surface and interface science and electronic structure theory are applied to investigate the structure and chemical properties of catalytically active particles and ultrathin films supported on oxide single crystals. These studies focus on structure-property relationships in vanadium oxide, tungsten oxide, and mixed V-W oxides on the surfaces of alpha-Al2O3 and alpha-Fe2O 3 (0001)-oriented single crystal substrates, two materials with nearly identical crystal structures but drastically different chemical properties. In situ synchrotron X-ray standing wave (XSW) measurements are sensitive to changes in the atomic-scale geometry of single crystal model catalyst surfaces through chemical reaction cycles, while X-ray photoelectron spectroscopy (XPS) reveals corresponding chemical changes. Experimental results agree with theoretical calculations of surface structures, allowing for detailed electronic structure investigations and predictions of surface chemical phenomena. The surface configurations and oxidation states of V and W are found to depend on the coverage of each, and reversible structural shifts accompany chemical state changes through reduction-oxidation cycles. Substrate-dependent effects suggest how the choice of oxide support material may affect catalytic behavior. Additionally, the structure and chemistry of W deposited on alpha-Fe 2O3 nanopowders is studied using X-ray absorption fine structure (XAFS) measurements in an attempt to bridge single crystal surface studies with real catalysts. These investigations of catalytically active material surfaces can inform the rational design of new catalysts for more efficient and sustainable chemistry.

Transport processes at fluidic interfaces

CERN Document Server

Reusken, Arnold

2017-01-01

There are several physico-chemical processes that determine the behavior of multiphase fluid systems – e.g., the fluid dynamics in the different phases and the dynamics of the interface(s), mass transport between the fluids, adsorption effects at the interface, and transport of surfactants on the interface – and result in heterogeneous interface properties. In general, these processes are strongly coupled and local properties of the interface play a crucial role. A thorough understanding of the behavior of such complex flow problems must be based on physically sound mathematical models, which especially account for the local processes at the interface. This book presents recent findings on the rigorous derivation and mathematical analysis of such models and on the development of numerical methods for direct numerical simulations. Validation results are based on specifically designed experiments using high-resolution experimental techniques. A special feature of this book is its focus on an interdisciplina...

Foldit Standalone: a video game-derived protein structure manipulation interface using Rosetta.

Science.gov (United States)

Kleffner, Robert; Flatten, Jeff; Leaver-Fay, Andrew; Baker, David; Siegel, Justin B; Khatib, Firas; Cooper, Seth

2017-09-01

Foldit Standalone is an interactive graphical interface to the Rosetta molecular modeling package. In contrast to most command-line or batch interactions with Rosetta, Foldit Standalone is designed to allow easy, real-time, direct manipulation of protein structures, while also giving access to the extensive power of Rosetta computations. Derived from the user interface of the scientific discovery game Foldit (itself based on Rosetta), Foldit Standalone has added more advanced features and removed the competitive game elements. Foldit Standalone was built from the ground up with a custom rendering and event engine, configurable visualizations and interactions driven by Rosetta. Foldit Standalone contains, among other features: electron density and contact map visualizations, multiple sequence alignment tools for template-based modeling, rigid body transformation controls, RosettaScripts support and an embedded Lua interpreter. Foldit Standalone is available for download at https://fold.it/standalone , under the Rosetta license, which is free for academic and non-profit users. It is implemented in cross-platform C ++ and binary executables are available for Windows, macOS and Linux. scooper@ccs.neu.edu. © The Author(s) 2017. Published by Oxford University Press.

MER SPICE Interface

Science.gov (United States)

Sayfi, Elias

2004-01-01

MER SPICE Interface is a software module for use in conjunction with the Mars Exploration Rover (MER) mission and the SPICE software system of the Navigation and Ancillary Information Facility (NAIF) at NASA's Jet Propulsion Laboratory. (SPICE is used to acquire, record, and disseminate engineering, navigational, and other ancillary data describing circumstances under which data were acquired by spaceborne scientific instruments.) Given a Spacecraft Clock value, MER SPICE Interface extracts MER-specific data from SPICE kernels (essentially, raw data files) and calculates values for Planet Day Number, Local Solar Longitude, Local Solar Elevation, Local Solar Azimuth, and Local Solar Time (UTC). MER SPICE Interface was adapted from a subroutine, denoted m98SpiceIF written by Payam Zamani, that was intended to calculate SPICE values for the Mars Polar Lander. The main difference between MER SPICE Interface and m98SpiceIf is that MER SPICE Interface does not explicitly call CHRONOS, a time-conversion program that is part of a library of utility subprograms within SPICE. Instead, MER SPICE Interface mimics some portions of the CHRONOS code, the advantage being that it executes much faster and can efficiently be called from a pipeline of events in a parallel processing environment.

High energy photoelectron spectroscopy in basic and applied science: Bulk and interface electronic structure

Energy Technology Data Exchange (ETDEWEB)

Knut, Ronny; Lindblad, Rebecka [Department of Physics and Astronomy, Uppsala University, SE-751 21 Uppsala (Sweden); Gorgoi, Mihaela [Helmholtz Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Str. 15, 12489 Berlin (Germany); Rensmo, Håkan [Department of Physics and Astronomy, Uppsala University, SE-751 21 Uppsala (Sweden); Karis, Olof, E-mail: olof.karis@physics.uu.se [Department of Physics and Astronomy, Uppsala University, SE-751 21 Uppsala (Sweden)

2013-10-15

Highlights: •We demonstrate how hard X-ray photoelectron spectroscopy can be used to investigate interface properties of multilayers. •By combining HAXPES and statistical methods we are able to provide quantitative analysis of the interface diffusion process. •We show how photoionization cross sections can be used to map partial density of states contributions to valence states. •We use HAXPES to provide insight into the valence electronic structure of e.g. multiferroics and dye-sensitized solar cells. -- Abstract: With the access of new high-performance electron spectrometers capable of analyzing electron energies up to the order of 10 keV, the interest for photoelectron spectroscopy has grown and many new applications of the technique in areas where electron spectroscopies were considered to have limited use have been demonstrated over the last few decades. The technique, often denoted hard X-ray photoelectron spectroscopy (HX-PES or HAXPES), to distinguish the experiment from X-ray photoelectron spectroscopy performed at lower energies, has resulted in an increasing interest in photoelectron spectroscopy in many areas. The much increased mean free path at higher kinetic energies, in combination with the elemental selectivity of the core level spectroscopies in general has led to this fact. It is thus now possible to investigate the electronic structure of materials with a substantially enhanced bulk sensitivity. In this review we provide examples from our own research using HAXPES which to date has been performed mainly at the HIKE facility at the KMC-1 beamline at HZB, Berlin. The review exemplifies the new opportunities using HAXPES to address both bulk and interface electronic properties in systems relevant for applications in magnetic storage, energy related research, but also in purely curiosity driven problems.

High energy photoelectron spectroscopy in basic and applied science: Bulk and interface electronic structure

International Nuclear Information System (INIS)

Knut, Ronny; Lindblad, Rebecka; Gorgoi, Mihaela; Rensmo, Håkan; Karis, Olof

2013-01-01

Highlights: •We demonstrate how hard X-ray photoelectron spectroscopy can be used to investigate interface properties of multilayers. •By combining HAXPES and statistical methods we are able to provide quantitative analysis of the interface diffusion process. •We show how photoionization cross sections can be used to map partial density of states contributions to valence states. •We use HAXPES to provide insight into the valence electronic structure of e.g. multiferroics and dye-sensitized solar cells. -- Abstract: With the access of new high-performance electron spectrometers capable of analyzing electron energies up to the order of 10 keV, the interest for photoelectron spectroscopy has grown and many new applications of the technique in areas where electron spectroscopies were considered to have limited use have been demonstrated over the last few decades. The technique, often denoted hard X-ray photoelectron spectroscopy (HX-PES or HAXPES), to distinguish the experiment from X-ray photoelectron spectroscopy performed at lower energies, has resulted in an increasing interest in photoelectron spectroscopy in many areas. The much increased mean free path at higher kinetic energies, in combination with the elemental selectivity of the core level spectroscopies in general has led to this fact. It is thus now possible to investigate the electronic structure of materials with a substantially enhanced bulk sensitivity. In this review we provide examples from our own research using HAXPES which to date has been performed mainly at the HIKE facility at the KMC-1 beamline at HZB, Berlin. The review exemplifies the new opportunities using HAXPES to address both bulk and interface electronic properties in systems relevant for applications in magnetic storage, energy related research, but also in purely curiosity driven problems

Local Electronic And Dielectric Properties at Nanosized Interfaces

Energy Technology Data Exchange (ETDEWEB)

Bonnell, Dawn A. [Univ. of Pennsylvania, Philadelphia, PA (United States)

2015-02-23

Final Report to the Department of Energy for period 6/1/2000 to 11/30/2014 for Grant # DE-FG02-00ER45813-A000 to the University of Pennsylvania Local Electronic And Dielectric Properties at Nanosized Interfaces PI: Dawn Bonnell The behavior of grain boundaries and interfaces has been a focus of fundamental research for decades because variations of structure and composition at interfaces dictate mechanical, electrical, optical and dielectric properties in solids. Similarly, the consequence of atomic and electronic structures of surfaces to chemical and physical interactions are critical due to their implications to catalysis and device fabrication. Increasing fundamental understanding of surfaces and interfaces has materially advanced technologies that directly bear on energy considerations. Currently, exciting developments in materials processing are enabling creative new electrical, optical and chemical device configurations. Controlled synthesis of nanoparticles, semiconducting nanowires and nanorods, optical quantum dots, etc. along with a range of strategies for assembling and patterning nanostructures portend the viability of new devices that have the potential to significantly impact the energy landscape. As devices become smaller the impact of interfaces and surfaces grows geometrically. As with other nanoscale phenomena, small interfaces do not exhibit the same properties as do large interfaces. The size dependence of interface properties had not been explored and understanding at the most fundamental level is necessary to the advancement of nanostructured devices. An equally important factor in the behavior of interfaces in devices is the ability to examine the interfaces under realistic conditions. For example, interfaces and boundaries dictate the behavior of oxide fuel cells which operate at extremely high temperatures in dynamic high pressure chemical environments. These conditions preclude the characterization of local properties during fuel cell

Optical fingerprints of solid-liquid interfaces: a joint ATR-IR and first principles investigation

Science.gov (United States)

Yang, L.; Niu, F.; Tecklenburg, S.; Pander, M.; Nayak, S.; Erbe, A.; Wippermann, S.; Gygi, F.; Galli, G.

Despite the importance of understanding the structural and bonding properties of solid-liquid interfaces for a wide range of (photo-)electrochemical applications, there are presently no experimental techniques available to directly probe the microscopic structure of solid-liquid interfaces. To develop robust strategies to interpret experiments and validate theory, we carried out attenuated total internal reflection (ATR-IR) spectroscopy measurements and ab initio molecular dynamics (AIMD) simulations of the vibrational properties of interfaces between liquid water and well-controlled prototypical semiconductor substrates. We show the Ge(100)/H2O interface to feature a reversible potential-dependent surface phase transition between Ge-H and Ge-OH termination. The Si(100)/H2O interface is proposed as a model system for corrosion and oxidation processes. We performed AIMD calculations under finite electric fields, revealing different pathways for initial oxidation. These pathways are predicted to exhibit unique spectral signatures. A significant increase in surface specificity can be achieved utilizing an angle-dependent ATR-IR experiment, which allows to detect such signatures at the interfacial layer and consequently changes in the hydrogen bond network. Funding from DOE-BES Grant No. DE-SS0008939 and the Deutsche Forschungsgemeinschaft (RESOLV, EXC 1069) are gratefully acknowledged.

Micro-Foundations of Product Interfaces and Their Implications on Product and Organization Design

DEFF Research Database (Denmark)

Donmez, Mehmet; Hsuan, Juliana

2016-01-01

by interfaces in addition to structural interdependencies. Our theoretical reasoning illustrates that the differentiation and integration role of interfaces and the functional and structural interdependencies managed by product interfaces inform three interface properties: structural thickness, functional......Despite the importance of product interfaces for product development organizations, little is known about how product interfaces manage component interdependencies. In order to answer this question, we make one of the initial attempts to define micro-foundational interface properties by building...... on and extending the seminal works of Simon (1962) and Parnas (1972) on which the literature on modularity and product architecture is built. Rather than being simple linkages, we show that interfaces exhibit a core-periphery structure by underlining the importance of functional interdependencies managed...

Effect of binding group on hybridization across the silicon/aromatic-monolayer interface

Energy Technology Data Exchange (ETDEWEB)

Toledano, Tal; Garrick, Rachel; Sinai, Ofer [Department of Materials and Interfaces, Weizmann Institute of Science, Rehovoth 76100 (Israel); Bendikov, Tatyana [Chemical Research Support, Weizmann Institute of Science, Rehovoth 76100 (Israel); Haj-Yahia, Abd-Elrazek [Department of Materials and Interfaces, Weizmann Institute of Science, Rehovoth 76100 (Israel); Lerman, Keti; Alon, Hadas; Sukenik, Chaim N. [Chemistry Department, Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 52900 (Israel); Vilan, Ayelet, E-mail: ayelet.vilan@weizmann.ac.il [Department of Materials and Interfaces, Weizmann Institute of Science, Rehovoth 76100 (Israel); Kronik, Leeor, E-mail: leeor.kronik@weizmann.ac.il [Department of Materials and Interfaces, Weizmann Institute of Science, Rehovoth 76100 (Israel); Cahen, David [Department of Materials and Interfaces, Weizmann Institute of Science, Rehovoth 76100 (Israel)

2015-10-01

We report a combined ultraviolet photoelectron spectroscopy (UPS) and density functional theory (DFT) study of the electronic structure of aromatic self-assembled monolayers covalently bound to Si, using several different aromatic groups (phenyl, biphenyl, and fluorene) and binding groups (O, NH, and CH{sub 2}). We obtain excellent agreement between theory and experiment, which allows for a detailed interpretation of the experimental results. Our analysis reveals a significant effect of the binding group on state hybridization at the organic/inorganic interface. Specifically, it highlights that lone-pair electrons in the binding atom facilitate hybridization between the aromatic system and the Si substrate, resulting in a significant induced density of interface states (IDIS). These interface states are manifested as a broadened HOMO peak in the experimental UPS data and are clearly observed in a theoretical spatially-resolved density of states map. This provides means to control the degree of coupling between substrate and molecule, which may prove useful in the design of transport across organic/inorganic interfaces.

Electronic structure of hybrid interfaces for polymer-based electronics

International Nuclear Information System (INIS)

Fahlman, M; Crispin, A; Crispin, X; Henze, S K M; Jong, M P de; Osikowicz, W; Tengstedt, C; Salaneck, W R

2007-01-01

The fundamentals of the energy level alignment at anode and cathode electrodes in organic electronics are described. We focus on two different models that treat weakly interacting organic/metal (and organic/organic) interfaces: the induced density of interfacial states model and the so-called integer charge transfer model. The two models are compared and evaluated, mainly using photoelectron spectroscopy data of the energy level alignment of conjugated polymers and molecules at various organic/metal and organic/organic interfaces. We show that two different alignment regimes are generally observed: (i) vacuum level alignment, which corresponds to the lack of vacuum level offsets (Schottky-Mott limit) and hence the lack of charge transfer across the interface, and (ii) Fermi level pinning where the resulting work function of an organic/metal and organic/organic bilayer is independent of the substrate work function and an interface dipole is formed due to charge transfer across the interface. We argue that the experimental results are best described by the integer charge transfer model which predicts the vacuum level alignment when the substrate work function is above the positive charge transfer level and below the negative charge transfer level of the conjugated material. The model further predicts Fermi level pinning to the positive (negative) charge transfer level when the substrate work function is below (above) the positive (negative) charge transfer level. The nature of the integer charge transfer levels depend on the materials system: for conjugated large molecules and polymers, the integer charge transfer states are polarons or bipolarons; for small molecules' highest occupied and lowest unoccupied molecular orbitals and for crystalline systems, the relevant levels are the valence and conduction band edges. Finally, limits and further improvements to the integer charge transfer model are discussed as well as the impact on device design. (topical review)

Using SNOMED CT to Represent Two Interface Terminologies

Science.gov (United States)

Rosenbloom, S. Trent; Brown, Steven H.; Froehling, David; Bauer, Brent A.; Wahner-Roedler, Dietlind L.; Gregg, William M.; Elkin, Peter L.

2009-01-01

Objective Interface terminologies are designed to support interactions between humans and structured medical information. In particular, many interface terminologies have been developed for structured computer based documentation systems. Experts and policy-makers have recommended that interface terminologies be mapped to reference terminologies. The goal of the current study was to evaluate how well the reference terminology SNOMED CT could map to and represent two interface terminologies, MEDCIN and the Categorical Health Information Structured Lexicon (CHISL). Design Automated mappings between SNOMED CT and 500 terms from each of the two interface terminologies were evaluated by human reviewers, who also searched SNOMED CT to identify better mappings when this was judged to be necessary. Reviewers judged whether they believed the interface terms to be clinically appropriate, whether the terms were covered by SNOMED CT concepts and whether the terms' implied semantic structure could be represented by SNOMED CT. Measurements Outcomes included concept coverage by SNOMED CT for study terms and their implied semantics. Agreement statistics and compositionality measures were calculated. Results The SNOMED CT terminology contained concepts to represent 92.4% of MEDCIN and 95.9% of CHISL terms. Semantic structures implied by study terms were less well covered, with some complex compositional expressions requiring semantics not present in SNOMED CT. Among sampled terms, those from MEDCIN were more complex than those from CHISL, containing an average 3.8 versus 1.8 atomic concepts respectively, pterms. PMID:18952944

Analysis of frequency-dependent series resistance and interface states of In/SiO{sub 2}/p-Si (MIS) structures

Energy Technology Data Exchange (ETDEWEB)

Birkan Selcuk, A. [Department of Nuclear Electronics and Instrumentation, Saraykoey Nuclear Research and Training Center, 06983 Saray, Ankara (Turkey); Tugluoglu, N. [Department of Nuclear Electronics and Instrumentation, Saraykoey Nuclear Research and Training Center, 06983 Saray, Ankara (Turkey)], E-mail: ntuglu@taek.gov.tr; Karadeniz, S.; Bilge Ocak, S. [Department of Nuclear Electronics and Instrumentation, Saraykoey Nuclear Research and Training Center, 06983 Saray, Ankara (Turkey)

2007-11-15

In this work, the investigation of the interface state density and series resistance from capacitance-voltage (C-V) and conductance-voltage (G/{omega}-V) characteristics in In/SiO{sub 2}/p-Si metal-insulator-semiconductor (MIS) structures with thin interfacial insulator layer have been reported. The thickness of SiO{sub 2} film obtained from the measurement of the oxide capacitance corrected for series resistance in the strong accumulation region is 220 A. The forward and reverse bias C-V and G/{omega}-V characteristics of MIS structures have been studied at the frequency range 30 kHz-1 MHz at room temperature. The frequency dispersion in capacitance and conductance can be interpreted in terms of the series resistance (R{sub s}) and interface state density (D{sub it}) values. Both the series resistance R{sub s} and density of interface states D{sub it} are strongly frequency-dependent and decrease with increasing frequency. The distribution profile of R{sub s}-V gives a peak at low frequencies in the depletion region and disappears with increasing frequency. Experimental results show that the interfacial polarization contributes to the improvement of the dielectric properties of In/SiO{sub 2}/p-Si MIS structures. The interface state density value of In/SiO{sub 2}/p-Si MIS diode calculated at strong accumulation region is 1.11x10{sup 12} eV{sup -1} cm{sup -2} at 1 MHz. It is found that the calculated value of D{sub it} ({approx}10{sup 12} eV{sup -1} cm{sup -2}) is not high enough to pin the Fermi level of the Si substrate disrupting the device operation.

The dimer interfaces of protease and extra-protease domains influence the activation of protease and the specificity of GagPol cleavage.

Science.gov (United States)

Pettit, Steven C; Gulnik, Sergei; Everitt, Lori; Kaplan, Andrew H

2003-01-01

Activation of the human immunodeficiency virus type 1 (HIV-1) protease is an essential step in viral replication. As is the case for all retroviral proteases, enzyme activation requires the formation of protease homodimers. However, little is known about the mechanisms by which retroviral proteases become active within their precursors. Using an in vitro expression system, we have examined the determinants of activation efficiency and the order of cleavage site processing for the protease of HIV-1 within the full-length GagPol precursor. Following activation, initial cleavage occurs between the viral p2 and nucleocapsid proteins. This is followed by cleavage of a novel site located in the transframe domain. Mutational analysis of the dimer interface of the protease produced differential effects on activation and specificity. A subset of mutations produced enhanced cleavage at the amino terminus of the protease, suggesting that, in the wild-type precursor, cleavages that liberate the protease are a relatively late event. Replacement of the proline residue at position 1 of the protease dimer interface resulted in altered cleavage of distal sites and suggests that this residue functions as a cis-directed specificity determinant. In summary, our studies indicate that interactions within the protease dimer interface help determine the order of precursor cleavage and contribute to the formation of extended-protease intermediates. Assembly domains within GagPol outside the protease domain also influence enzyme activation.

Design of Wireless GPIB Interface Module Based on Bluetooth

International Nuclear Information System (INIS)

Fu, P; Ma, W J; Huang, C J

2006-01-01

GPIB interface is widely used in the testing and control field. In this paper a wireless GPIB interface module based on Bluetooth is developed. Programming with Verilog HDL language on the hardware of ROK 101 008 and a FPGA chip, the complicated logical design of GPIB interface and the Bluetooth data processing unit are implemented. On basis of Bluetooth specifications, the software for the control computer is developed. In order to provide a standard software interface for users, a VISA library that is compatible with the VPP specifications is also designed

Design of Wireless GPIB Interface Module Based on Bluetooth

Energy Technology Data Exchange (ETDEWEB)

Fu, P [Department of Automatic Testing and Control, Harbin Institute of Technology, Harbin 150001 (China); Ma, W J [Department of Automatic Testing and Control, Harbin Institute of Technology, Harbin 150001 (China); Huang, C J [Department of Automatic Testing and Control, Harbin Institute of Technology, Harbin 150001 (China)

2006-10-15

GPIB interface is widely used in the testing and control field. In this paper a wireless GPIB interface module based on Bluetooth is developed. Programming with Verilog HDL language on the hardware of ROK 101 008 and a FPGA chip, the complicated logical design of GPIB interface and the Bluetooth data processing unit are implemented. On basis of Bluetooth specifications, the software for the control computer is developed. In order to provide a standard software interface for users, a VISA library that is compatible with the VPP specifications is also designed.

TMS communications software. Volume 2: Bus interface unit

Science.gov (United States)

Gregor, P. J.

1979-01-01

A data bus communication system to support the space shuttle's Trend Monitoring System (TMS) and to provide a basis for evaluation of the bus concept is described. Installation of the system included developing both hardware and software interfaces between the bus and the specific TMS computers and terminals. The software written for the microprocessor-based bus interface units is described. The software implements both the general bus communications protocol and also the specific interface protocols for the TMS computers and terminals.

Interface Fracture in Adhesively Bonded Shell Structures

DEFF Research Database (Denmark)

Jensen, Henrik Myhre

2008-01-01

Two methods for the prediction of crack propagation through the interface of adhesively bonded shells are discussed. One is based on a fracture mechanics approach; the other is based on a cohesive zone approach. Attention is focussed on predicting the shape of the crack front and the critical...

X-ray scattering studies of surfaces and interfaces

International Nuclear Information System (INIS)

Sanyal, M.K.

1998-01-01

Here we shall briefly review the basics and some applications of x-ray specular reflectivity and diffuse scattering techniques. These x-ray scattering techniques are uniquely suited to study of the structure of surfaces and interfaces at atomic resolutions as they are nondestructive and can probe even interfaces which are buried. The study of structure of surfaces and interfaces is not only required in understanding physics in reduced dimensions but is also essential in developing technologically important materials

Passive scalar dynamics near the turbulent/nonturbulent interface in a jet

Science.gov (United States)

Taveira, Rodrigo R.; da Silva, Carlos

2011-11-01

The present work uses several direct numerical simulations (DNS) of turbulent planar jets at Reynolds number ranging from Reλ = 120 to Reλ = 160 and Schmidt numbers raging from Sc = 0 . 7 to 7.0 to analyze the nature and properties of the ``scalar interface'' and to investigate the dynamics of turbulent mixing of a passive scalar. Specifically, we employ conditional statistics in relation to the distance from the T/NT interface in order to eliminate the intermittency that affects common turbulence statistics close to the jet edge. The physical mechanisms behind scalar mixing near the T/NT interfaces and their associated turbulent scales and topology are investigated. A sharp scalar interface exists separating the Turbulent and the irrotational flow regions. The thickness of this scalar interface δθ is also of the order of the Taylor micro-scale, λ. However, the thickness of the scalar gradient variance I (where Gj = ∂ θ / ∂xj) is much smaller. Very intense scalar gradient sheet structures along regions of intense strain, in particular at the T/NT interface. The scalar gradient transport equation is analyzed in order to further investigate the physical mechanism of scalar turbulent mixing at the jet edge. Almost all mixing takes place in a confined region close to the interface, beyond which they become reduced to an almost in perfect - balance between production and dissipation of scalar variance.

Oxide surfaces and metal/oxide interfaces studied by grazing incidence X-ray scattering

Science.gov (United States)

Renaud, Gilles

Experimental determinations of the atomic structure of insulating oxide surfaces and metal/oxide interfaces are scarce, because surface science techniques are often limited by the insulating character of the substrate. Grazing incidence X-ray scattering (GIXS), which is not subject to charge effects, can provide very precise information on the atomic structure of oxide surfaces: roughness, relaxation and reconstruction. It is also well adapted to analyze the atomic structure, the registry, the misfit relaxation, elastic or plastic, the growth mode and the morphology of metal/oxide interfaces during their growth, performed in situ. GIXS also allows the analysis of thin films and buried interfaces, in a non-destructive way, yielding the epitaxial relationships, and, by variation of the grazing incidence angle, the lattice parameter relaxation along the growth direction. On semi-coherent interfaces, the existence of an ordered network of interfacial misfit dislocations can be demonstrated, its Burger's vector determined, its ordering during in situ annealing cycles followed, and sometimes even its atomic structure can be addressed. Careful analysis during growth allows the modeling of the dislocation nucleation process. This review emphasizes the new information that GIXS can bring to oxide surfaces and metal/oxide interfaces by comparison with other surface science techniques. The principles of X-ray diffraction by surfaces and interfaces are recalled, together with the advantages and properties of grazing angles. The specific experimental requirements are discussed. Recent results are presented on the determination of the atomic structure of relaxed or reconstructed oxide surfaces. A description of results obtained during the in situ growth of metal on oxide surfaces is also given, as well as investigations of thick metal films on oxide surfaces, with lattice parameter misfit relaxed by an array of dislocations. Recent work performed on oxide thin films having

The Johnson Space Center Management Information Systems (JSCMIS): An interface for organizational databases

Science.gov (United States)

Bishop, Peter C.; Erickson, Lloyd

1990-01-01

The Management Information and Decision Support Environment (MIDSE) is a research activity to build and test a prototype of a generic human interface on the Johnson Space Center (JSC) Information Network (CIN). The existing interfaces were developed specifically to support operations rather than the type of data which management could use. The diversity of the many interfaces and their relative difficulty discouraged occasional users from attempting to use them for their purposes. The MIDSE activity approached this problem by designing and building an interface to one JSC data base - the personnel statistics tables of the NASA Personnel and Payroll System (NPPS). The interface was designed against the following requirements: generic (use with any relational NOMAD data base); easy to learn (intuitive operations for new users); easy to use (efficient operations for experienced users); self-documenting (help facility which informs users about the data base structure as well as the operation of the interface); and low maintenance (easy configuration to new applications). A prototype interface entitled the JSC Management Information Systems (JSCMIS) was produced. It resides on CIN/PROFS and is available to JSC management who request it. The interface has passed management review and is ready for early use. Three kinds of data are now available: personnel statistics, personnel register, and plan/actual cost.

Simulation of Magnetic Phenomena at Realistic Interfaces

KAUST Repository

Grytsyuk, Sergiy

2016-02-04

In modern technology exciting developments are related to the ability to understand and control interfaces. Particularly, magnetic interfaces revealing spindependent electron transport are of great interest for modern spintronic devices, such as random access memories and logic devices. From the technological point of view, spintronic devices based on magnetic interfaces enable manipulation of the magnetism via an electric field. Such ability is a result of the different quantum effects arising from the magnetic interfaces (for example, spin transfer torque or spin-orbit torque) and it can reduce the energy consumption as compared to the traditional semiconductor electronic devices. Despite many appealing characteristics of these materials, fundamental understanding of their microscopic properties and related phenomena needs to be established by thorough investigation. In this work we implement first principles calculations in order to study the structural, electric, and magnetic properties as well as related phenomena of two types of interfaces with large potential in spintronic applications: 1) interfaces between antiferromagnetic 3d-metal-oxides and ferromagnetic 3d-metals and 2) interfaces between non-magnetic 5d(4d)- and ferromagnetic 3d-metals. A major difficulty in studying such interfaces theoretically is the typically large lattice mismatch. By employing supercells with Moir e patterns, we eliminate the artificial strain that leads to doubtful results and are able to describe the dependence of the atomic density at the interfaces on the component materials and their thicknesses. After establishing understanding about the interface structures, we investigate the electronic and magnetic properties. A Moir e supercell with transition layer is found to reproduce the main experimental findings and thus turns out to be the appropriate model for simulating magnetic misfit interfaces. In addition, we systematically study the magnetic anisotropy and Rashba band

Specificity of Structural Assessment of Knowledge

Science.gov (United States)

Trumpower, David L.; Sharara, Harold; Goldsmith, Timothy E.

2010-01-01

This study examines the specificity of information provided by structural assessment of knowledge (SAK). SAK is a technique which uses the Pathfinder scaling algorithm to transform ratings of concept relatedness into network representations (PFnets) of individuals' knowledge. Inferences about individuals' overall domain knowledge based on the…

Energy band structure and electrical properties of Ga-oxide/GaN interface formed by remote oxygen plasma

Science.gov (United States)

Yamamoto, Taishi; Taoka, Noriyuki; Ohta, Akio; Truyen, Nguyen Xuan; Yamada, Hisashi; Takahashi, Tokio; Ikeda, Mitsuhisa; Makihara, Katsunori; Nakatsuka, Osamu; Shimizu, Mitsuaki; Miyazaki, Seiichi

2018-06-01

The energy band structure of a Ga-oxide/GaN structure formed by remote oxygen plasma exposure and the electrical interface properties of the GaN metal–oxide–semiconductor (MOS) capacitors with the SiO2/Ga-oxide/GaN structures with postdeposition annealing (PDA) at various temperatures have been investigated. Reflection high-energy electron diffraction and X-ray photoelectron spectroscopy clarified that the formed Ga-oxide layer is neither a single nor polycrystalline phase with high crystallinity. We found that the energy band offsets at the conduction band minimum and at the valence band maximum between the Ga-oxide layer and the GaN surface were 0.4 and 1.2 ± 0.2 eV, respectively. Furthermore, capacitance–voltage (C–V) characteristics revealed that the interface trap density (D it) is lower than the evaluation limit of Terman method without depending on the PDA temperatures, and that the SiO2/Ga-oxide stack can work as a protection layer to maintain the low D it, avoiding the significant decomposition of GaN at the high PDA temperature of 800 °C.

Integrating interface slicing into software engineering processes

Science.gov (United States)

Beck, Jon

1993-01-01

Interface slicing is a tool which was developed to facilitate software engineering. As previously presented, it was described in terms of its techniques and mechanisms. The integration of interface slicing into specific software engineering activities is considered by discussing a number of potential applications of interface slicing. The applications discussed specifically address the problems, issues, or concerns raised in a previous project. Because a complete interface slicer is still under development, these applications must be phrased in future tenses. Nonetheless, the interface slicing techniques which were presented can be implemented using current compiler and static analysis technology. Whether implemented as a standalone tool or as a module in an integrated development or reverse engineering environment, they require analysis no more complex than that required for current system development environments. By contrast, conventional slicing is a methodology which, while showing much promise and intuitive appeal, has yet to be fully implemented in a production language environment despite 12 years of development.

Structured Additive Regression Models: An R Interface to BayesX

Directory of Open Access Journals (Sweden)

Nikolaus Umlauf

2015-02-01

Full Text Available Structured additive regression (STAR models provide a flexible framework for model- ing possible nonlinear effects of covariates: They contain the well established frameworks of generalized linear models and generalized additive models as special cases but also allow a wider class of effects, e.g., for geographical or spatio-temporal data, allowing for specification of complex and realistic models. BayesX is standalone software package providing software for fitting general class of STAR models. Based on a comprehensive open-source regression toolbox written in C++, BayesX uses Bayesian inference for estimating STAR models based on Markov chain Monte Carlo simulation techniques, a mixed model representation of STAR models, or stepwise regression techniques combining penalized least squares estimation with model selection. BayesX not only covers models for responses from univariate exponential families, but also models from less-standard regression situations such as models for multi-categorical responses with either ordered or unordered categories, continuous time survival data, or continuous time multi-state models. This paper presents a new fully interactive R interface to BayesX: the R package R2BayesX. With the new package, STAR models can be conveniently specified using Rs formula language (with some extended terms, fitted using the BayesX binary, represented in R with objects of suitable classes, and finally printed/summarized/plotted. This makes BayesX much more accessible to users familiar with R and adds extensive graphics capabilities for visualizing fitted STAR models. Furthermore, R2BayesX complements the already impressive capabilities for semiparametric regression in R by a comprehensive toolbox comprising in particular more complex response types and alternative inferential procedures such as simulation-based Bayesian inference.

Natural gesture interfaces

Science.gov (United States)

Starodubtsev, Illya

2017-09-01

The paper describes the implementation of the system of interaction with virtual objects based on gestures. The paper describes the common problems of interaction with virtual objects, specific requirements for the interfaces for virtual and augmented reality.

NMR studies of interfaces, strain and anisotropy in Co/Cu multilayers

International Nuclear Information System (INIS)

Thomson, T.; Riedi, P.C.

1999-01-01

59 Co NMR studies of multilayers are able to give three direct pieces of information: (i) the crystal phase of Co, fcc (217.4 MHz), hcp (220-228 MHz) and in exotic cases bcc (198 MHz) for films measured at T= 4.2 K, (ii) the nature of the interfaces from low frequency satellite lines, and (iii) the strain state deduced from small changes in the line positions. Extensive studies of Co/Cu multilayer interfacial structures as a function of deposition technique, layer thickness, substrate/buffer layer structure and annealing temperature have been undertaken. This work has shed new light on the relationship between interfacial structure and magnetoresistance and in particular has demonstrated that flat, atomic scale, interfaces lead to greater magnetoresistance. The difference between the Co and Cu lattice constant results in an extensive, tensile in-plane strain developing in Co layers provided that some epitaxial registry is present. Information on strain effects can be obtained from the position and width of the NMR lines. The magnetic anisotropy field can be determined by measuring the field dependence of the enhancement effect due to electronic magnetisation. This provides unique insight into the distribution of magnetic anisotropy within the Co layers, as the enhancement can be investigated independently for each NMR line and, hence, provides environment specific information on magnetic anisotropy at the interfaces and in the interior of the layers

Preliminary identification of interfaces for certification and transfer of TRU waste to WIPP

International Nuclear Information System (INIS)

Whitty, W.J.; Ostenak, C.A.; Pillay, K.K.S.

1982-02-01

This study complements the national program to certify that newly generated and stored, unclassified defense transuranic (TRU) wastes meet the Waste Isolation Pilot Plant (WIPP) Waste Acceptance Criteria. The objectives of this study were to identify (1) the existing organizational structure at each of the major waste-generating and shipping sites and (2) the necessary interfaces between the waste shippers and WIPP. The interface investigations considered existing waste management organizations at the shipping sites and the proposed WIPP organization. An effort was made to identify the potential waste-certifying authorities and the lines of communication within these organizations. The long-range goal of this effort is to develop practicable interfaces between waste shippers and WIPP to enable the continued generation, interim storage, and eventual shipment of certified TRU wastes to WIPP. Some specific needs identified in this study include: organizational responsibility for certification procedures and quality assurance (QA) program; simple QA procedures; and specification and standardization of reporting forms and procedures, waste containers, and container labeling, color coding, and code location

Structural and Chemical Analysis of the Zirconia-Veneering Ceramic Interface.

Science.gov (United States)

Inokoshi, M; Yoshihara, K; Nagaoka, N; Nakanishi, M; De Munck, J; Minakuchi, S; Vanmeensel, K; Zhang, F; Yoshida, Y; Vleugels, J; Naert, I; Van Meerbeek, B

2016-01-01

The interfacial interaction of veneering ceramic with zirconia is still not fully understood. This study aimed to characterize morphologically and chemically the zirconia-veneering ceramic interface. Three zirconia-veneering conditions were investigated: 1) zirconia-veneering ceramic fired on sandblasted zirconia, 2) zirconia-veneering ceramic on as-sintered zirconia, and 3) alumina-veneering ceramic (lower coefficient of thermal expansion [CTE]) on as-sintered zirconia. Polished cross-sectioned ceramic-veneered zirconia specimens were examined using field emission gun scanning electron microscopy (Feg-SEM). In addition, argon-ion thinned zirconia-veneering ceramic interface cross sections were examined using scanning transmission electron microscopy (STEM)-energy dispersive X-ray spectrometry (EDS) at high resolution. Finally, the zirconia-veneering ceramic interface was quantitatively analyzed for tetragonal-to-monoclinic phase transformation and residual stress using micro-Raman spectroscopy (µRaman). Feg-SEM revealed tight interfaces for all 3 veneering conditions. High-resolution transmission electron microscopy (HRTEM) disclosed an approximately 1.0-µm transformed zone at sandblasted zirconia, in which distinct zirconia grains were no longer observable. Straight grain boundaries and angular grain corners were detected up to the interface of zirconia- and alumina-veneering ceramic with as-sintered zirconia. EDS mapping disclosed within the zirconia-veneering ceramic a few nanometers thick calcium/aluminum-rich layer, touching the as-sintered zirconia base, with an equally thick silicon-rich/aluminum-poor layer on top. µRaman revealed t-ZrO2-to-m-ZrO2 phase transformation and residual compressive stress at the sandblasted zirconia surface. The difference in CTE between zirconia- and the alumina-veneering ceramic resulted in residual tensile stress within the zirconia immediately adjacent to its interface with the veneering ceramic. The rather minor chemical

Turbulence structure and CO2 transfer at the air-sea interface and turbulent diffusion in thermally-stratified flows

International Nuclear Information System (INIS)

Komori, S.

1996-01-01

A supercomputer is a nice tool for simulating environmental flows. The Center for Global Environmental Research (CGER) of the National Institute for Environmental Studies purchased a supercomputer SX-3 of CGER about three years ago, and it has been used for various environmental simulations since. Although one of the main purposes for which the supercomputer was used was to simulate global warming with a general circulation model (GCM), our research organization used the supercomputer for more fundamental work to investigate heat and mass transfer mechanisms in environmental flows. Our motivations for this work was the fact that GCMs involve a number of uncertain submodels related to heat and mass transfer in turbulent atmospheric and oceanic flows. It may be easy to write research reports by running GCMs which were developed in western countries, but it is difficult for numerical scientists to do original work with such second-hand GCMs. In this sense, we thought that it would be more original to study the fundamentals of heat and mass transfer mechanisms in environmental flows rather than to run a GCM. Therefore, we tried to numerically investigate turbulence structure and scalar transfer both at the air-sea interface and in thermally stratified flows, neither of which were well modeled by GCMs. We also employed laboratory experiments to clarify the turbulence structure and scalar transfer mechanism, since numerical simulations are not sufficiently powerful to clarify all aspects of turbulence structure and scalar transfer mechanisms. A numerical technique is a promising tool to complement measurements of processes that cannot be clarified by turbulence measurements in environmental flows. It should also be noted that most of the interesting phenomena in environmental flows can be elucidated by laboratory or field measurements but not by numerical simulations alone. Thus, it is of importance to combine laboratory or field measurements with numerical simulations

Specific-structured lipids: nutritional perspectives and production potentials

DEFF Research Database (Denmark)

Xu, Xuebing; Høy, Carl-Erik; Balchen, Steen

1997-01-01

Structured lipids are referring to any triacylglycerols containing both long chain fatty acids (mostly essential fatty acids) and medium or short chain fatty acids. In case of specific-structured lipids (SSLs), each group of fatty acids locates specifically at sn-2 or -1.3 positions of the glycerol...... backbone. Recently the nutritional perspectives of this kind of lipids attract many interests. This causes an increasing interest in the production of them by lipase-catalyzed interesterification. One of the advantages of lipase method over chemical ones is that SSLs can be produced with particular fatty...

FASTBUS interface for the 3081/E

International Nuclear Information System (INIS)

Barker, L.; Kunz, P.F.; Lankford, A.J.; Oxoby, G.; Paffrath, L.; Rankin, P.; Trang, Q.

1985-09-01

The design of a FASTBUS interface to the 3081/E is presented. The interface consists of two boards, one specific to FASTBUS, the other usable by other interfaces to the 3081/E. The FASTBUS board is a dual-ported slave, permitting access from either of two cable segments. The general purpose board supports transfers to and from 3081/E memory and provides control of program execution. It also has several features which facilitate software debugging

First-Principles Study of the Polar TiC/Ti Interface

Institute of Scientific and Technical Information of China (English)

Limin LIU; Shaoqing WANG; Hengqiang YE

2003-01-01

The interface structure, work of adhesion, and bonding character of the polar TiC/Ti interface have been examined by the first-principles density functional plane-wave pseudopotential calculations. Both Ti- and C-terminated interfaces including six different interface structures were calculated, which present quite different features. For the Ti-terminated interface, the interfacial Ti-Ti bond has a strong metallic and weak covalent character; while for the C-terminated interface, the interfacial bond is a strong polar covalent interaction between the Ti-3d and C-2p orbital.The work of adhesion of C-terminated interface is nearly 9 J/m2 stronger than that of the Ti-terminated. It is found that each termination has relatively large work of adhesion, which is consistent with other polar interfaces.

Distributed user interfaces for clinical ubiquitous computing applications.

Science.gov (United States)

Bång, Magnus; Larsson, Anders; Berglund, Erik; Eriksson, Henrik

2005-08-01

Ubiquitous computing with multiple interaction devices requires new interface models that support user-specific modifications to applications and facilitate the fast development of active workspaces. We have developed NOSTOS, a computer-augmented work environment for clinical personnel to explore new user interface paradigms for ubiquitous computing. NOSTOS uses several devices such as digital pens, an active desk, and walk-up displays that allow the system to track documents and activities in the workplace. We present the distributed user interface (DUI) model that allows standalone applications to distribute their user interface components to several devices dynamically at run-time. This mechanism permit clinicians to develop their own user interfaces and forms to clinical information systems to match their specific needs. We discuss the underlying technical concepts of DUIs and show how service discovery, component distribution, events and layout management are dealt with in the NOSTOS system. Our results suggest that DUIs--and similar network-based user interfaces--will be a prerequisite of future mobile user interfaces and essential to develop clinical multi-device environments.

Ab Initio Study of the Atomic Level Structure of the Rutile TiO2(110)-Titanium Nitride (TiN) Interface.

Science.gov (United States)

Gutiérrez Moreno, José Julio; Nolan, Michael

2017-11-01

Titanium nitride (TiN) is widely used in industry as a protective coating due to its hardness and resistance to corrosion and can spontaneously form a thin oxide layer when it is exposed to air, which could modify the properties of the coating. With limited understanding of the TiO 2 -TiN interfacial system at present, this work aims to describe the structural and electronic properties of oxidized TiN based on a density functional theory (DFT) study of the rutile TiO 2 (110)-TiN(100) interface model system, also including Hubbard +U correction on Ti 3d states. The small lattice mismatch gives a good stability to the TiO 2 -TiN interface after depositing the oxide onto TiN through the formation of interfacial Ti-O bonds. Our DFT+U study shows the presence of Ti 3+ cations in the TiO 2 region, which are preferentially located next to the interface region as well as the rotation of the rutile TiO 2 octahedra in the interface structure. The DFT+U TiO 2 electronic density of states (EDOS) shows localized Ti 3+ defect states forming in the midgap between the top edge of the valence and the bottom of the conduction band. We increase the complexity of our models by the introduction of nonstoichiometric compositions. Although the vacancy formation energies for Ti in TiN (E vac (Ti) ≥ 4.03 eV) or O in the oxide (E vac (O) ≥ 3.40 eV) are quite high relative to perfect TiO 2 -TiN, defects are known to form during the oxide growth and can therefore be present after TiO 2 formation. Our results show that a structure with exchanged O and N can lie 0.82 eV higher in energy than the perfect system, suggesting the stability of structures with interdiffused O and N anions at ambient conditions. The presence of N in TiO 2 introduces N 2p states localized between the top edge of the O 2p valence states and the midgap Ti 3+ 3d states, thus reducing the band gap in the TiO 2 region for the exchanged O/N interface EDOS. The outcomes of these simulations give us a most comprehensive

Coordination structure of adsorbed Zn(II) at Water-TiO2 interfaces

Energy Technology Data Exchange (ETDEWEB)

He, G.; Pan, G.; Zhang, M.; Waychunas, G.A.

2011-01-15

The local structure of aqueous metal ions on solid surfaces is central to understanding many chemical and biological processes in soil and aquatic environments. Here, the local coordination structure of hydrated Zn(II) at water-TiO{sub 2} interfaces was identified by extended X-ray absorption fine structure (EXAFS) and X-ray absorption near-edge structure (XANES) spectroscopy combined with density functional theory (DFT) calculations. A nonintegral coordination number of average {approx}4.5 O atoms around a central Zn atom was obtained by EXAFS analysis. DFT calculations indicated that this coordination structure was consistent with the mixture of 4-coordinated bidentate binuclear (BB) and 5-coordinated bidentate mononuclear (BM) metastable equilibrium adsorption (MEA) states. The BB complex has 4-coordinated Zn, while the monodentate mononuclear (MM) complex has 6-coordinated Zn, and a 5-coordinated adsorbed Zn was found in the BM adsorption mode. DFT calculated energies showed that the lower-coordinated BB and BM modes were thermodynamically more favorable than the higher-coordinated MM MEA state. The experimentally observed XANES fingerprinting provided additional direct spectral evidence of 4- and 5-coordinated Zn-O modes. The overall spectral and computational evidence indicated that Zn(II) can occur in 4-, 5-, and 6-oxygen coordinated sites in different MEA states due to steric hindrance effects, and the coexistence of different MEA states formed the multiple coordination environments.

Computational and experimental analyses of the wave propagation through a bar structure including liquid-solid interface

Energy Technology Data Exchange (ETDEWEB)

Park, Sang Jin [UST Graduate School, Daejeon (Korea, Republic of); Rhee, Hui Nam [Division of Mechanical and Aerospace Engineering, Sunchon National University, Sunchon (Korea, Republic of); Yoon, Doo Byung; Park, Jin Ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-08-15

In this research, we study the propagation of longitudinal and transverse waves through a metal rod including a liquid layer using computational and experimental analyses. The propagation characteristics of longitudinal and transverse waves obtained by the computational and experimental analyses were consistent with the wave propagation theory for both cases, that is, the homogeneous metal rod and the metal rod including a liquid layer. The fluid-structure interaction modeling technique developed for the computational wave propagation analysis in this research can be applied to the more complex structures including solid-liquid interfaces.

Acetylcholine-Binding Protein Engineered to Mimic the α4-α4 Binding Pocket in α4β2 Nicotinic Acetylcholine Receptors Reveals Interface Specific Interactions Important for Binding and Activity

DEFF Research Database (Denmark)

Shahsavar, Azadeh; Ahring, Philip K; Olsen, Jeppe A

2015-01-01

Neuronal α4β2 nicotinic acetylcholine receptors are attractive drug targets for psychiatric and neurodegenerative disorders and smoking cessation aids. Recently, a third agonist binding site between two α4 subunits in the (α4)(3)(β2)(2) receptor subpopulation was discovered. In particular, three......-yl)-1,4-diazepane], highlights the roles of the three residues in determining binding affinities and functional properties of ligands at the α4-α4 interface. Confirmed by mutational studies, our structures suggest a unique ligand-specific role of residue H142 on the α4 subunit. In the cocrystal...... that could not be predicted based on wild-type Ls-AChBP structures in complex with the same agonists. The results show that an unprecedented correlation between binding in engineered AChBPs and functional receptors can be obtained and provide new opportunities for structure-based design of drugs targeting...

Specific interface area and self-stirring in a two-liquid system experiencing intense interfacial boiling below the bulk boiling temperatures of both components

Science.gov (United States)

Goldobin, Denis S.; Pimenova, Anastasiya V.

2017-04-01

We present an approach to theoretical assessment of the mean specific interface area (δ S/δ V) for a well-stirred system of two immiscible liquids experiencing interfacial boiling. The assessment is based on the balance of transformations of mechanical energy and the laws of the momentum and heat transfer in the turbulent boundary layer. The theory yields relations between the specific interface area and the characteristics of the system state. In particular, this allows us to derive the equations of self-cooling dynamics of the system in the absence of external heat supply. The results provide possibility for constructing a self-contained mathematical description of the process of interfacial boiling. In this study, we assume the volume fractions of two components to be similar as well as the values of their kinematic viscosity and molecular heat diffusivity.

Interface manipulation in GaxIn1-xAs/InP multiple layer structures grown by chemical beam epitaxy

NARCIS (Netherlands)

Rongen, R.T.H.; van Rijswijk, A.J.C.; Leijs, M.R.; Es, van C.M.; Vonk, H.; Wolter, J.H.

1997-01-01

In this study the control of interfacial layers in nanometre thin heterostructures is demonstrated by variation of the growth interruption sequence (GIS) at the binary - ternary interfaces. All samples have been prepared by chemical beam epitaxy simultaneously growing the structures on exact (100)

Advanced Stellar Compass - Adeos II - Interface Control Document

DEFF Research Database (Denmark)

Betto, Maurizio; Jørgensen, John Leif; Kilsgaard, Søren

of Automation of the Technical University of Denmark.The document is structured as follows. First we present the ASC - heritage, system description, performance - then we address more specifically the environmental properties, like the EMC compatibility and thermal characteristics, and the design...... and reliability issues. Section 6 deals with the testing and the calibration procedures and in section 7 the mechanical and electrical interfaces are given. In section 8 and 9 we address issues like manufacturing, transportation and storage, in section 10 the requirements imposed by the ASC on the system...

User interface for a tele-operated robotic hand system

Science.gov (United States)

Crawford, Anthony L

2015-03-24

Disclosed here is a user interface for a robotic hand. The user interface anchors a user's palm in a relatively stationary position and determines various angles of interest necessary for a user's finger to achieve a specific fingertip location. The user interface additionally conducts a calibration procedure to determine the user's applicable physiological dimensions. The user interface uses the applicable physiological dimensions and the specific fingertip location, and treats the user's finger as a two link three degree-of-freedom serial linkage in order to determine the angles of interest. The user interface communicates the angles of interest to a gripping-type end effector which closely mimics the range of motion and proportions of a human hand. The user interface requires minimal contact with the operator and provides distinct advantages in terms of available dexterity, work space flexibility, and adaptability to different users.

Steady distribution structure of point defects near crystal-melt interface under pulling stop of CZ Si crystal

Science.gov (United States)

Abe, T.; Takahashi, T.; Shirai, K.

2017-02-01

In order to reveal a steady distribution structure of point defects of no growing Si on the solid-liquid interface, the crystals were grown at a high pulling rate, which Vs becomes predominant, and the pulling was suddenly stopped. After restoring the variations of the crystal by the pulling-stop, the crystals were then left in prolonged contact with the melt. Finally, the crystals were detached and rapidly cooled to freeze point defects and then a distribution of the point defects of the as-grown crystals was observed. As a result, a dislocation loop (DL) region, which is formed by the aggregation of interstitials (Is), was formed over the solid-liquid interface and was surrounded with a Vs-and-Is-free recombination region (Rc-region), although the entire crystals had been Vs rich in the beginning. It was also revealed that the crystal on the solid-liquid interface after the prolonged contact with the melt can partially have a Rc-region to be directly in contact with the melt, unlike a defect distribution of a solid-liquid interface that has been growing. This experimental result contradicts a hypothesis of Voronkov's diffusion model, which always assumes the equilibrium concentrations of Vs and Is as the boundary condition for distribution of point defects on the growth interface. The results were disscussed from a qualitative point of view of temperature distribution and thermal stress by the pulling-stop.

Preliminary Specifications for the PS Transverse Damper Control Interface

CERN Document Server

Blas, A

2003-01-01

The transverse feedback system foreseen for the PS in 2004 is composed of different units to be remotely controlled and monitored: the pick-up amplifiers, the DSPU, the fine delay, the driver and power amplifiers. A special VME unit being dedicated to the pick-up amplifier ("The VMOD-TRX: a device for communication with remote instrumentation", A. Barreira Sevillano, J. Belleman, PS/BD/Note 96-02), the new interface will have to deal with the remaining parts of the loop.

The analog CTS communication interface in nuclear logging

International Nuclear Information System (INIS)

Li Min

2000-01-01

The author introduced a micro-controller-based CTS communication interface in nuclear logging, which provided convenience for the overhaul and regulation of the logging tool in CTS communication system. The use of micro-controller simplified the hardware structure of the interface, made the soft structure more rational and the whole system more flexible to control

A triclinic crystal structure of the carboxy-terminal domain of HIV-1 capsid protein with four molecules in the asymmetric unit reveals a novel packing interface

International Nuclear Information System (INIS)

Lampel, Ayala; Yaniv, Oren; Berger, Or; Bacharach, Eran; Gazit, Ehud; Frolow, Felix

2013-01-01

The triclinic structure of the HIV-1 capsid protein contains four molecules in the asymmetric unit that form a novel packing interface that could conceivably resemble an intermediate structure that is involved in the early steps of HIV-1 assembly. The Gag precursor is the major structural protein of the virion of human immunodeficiency virus-1 (HIV-1). Capsid protein (CA), a cleavage product of Gag, plays an essential role in virus assembly both in Gag-precursor multimerization and in capsid core formation. The carboxy-terminal domain (CTD) of CA contains 20 residues that are highly conserved across retroviruses and constitute the major homology region (MHR). Genetic evidence implies a role for the MHR in interactions between Gag precursors during the assembly of the virus, but the structural basis for this role remains elusive. This paper describes a novel triclinic structure of the HIV-1 CA CTD at 1.6 Å resolution with two canonical dimers of CA CTD in the asymmetric unit. The canonical dimers form a newly identified packing interface where interactions of four conserved MHR residues take place. This is the first structural indication that these MHR residues participate in the putative CTD–CTD interactions. These findings suggest that the molecules forming this novel interface resemble an intermediate structure that participates in the early steps of HIV-1 assembly. This interface may therefore provide a novel target for antiviral drugs

Human-system interface for CAREM nuclear reactor

International Nuclear Information System (INIS)

Abaurre, Norberto F.; Flury, Celso A.; Pierini, Juan P.; Etchepareborda, Andres; Breitembuecher, Alfredo J.; Lema, Fabian M.

2009-01-01

Associated with activities to be developed by our working group on the construction of the reactor training simulator for the CAREM, we have planned the design of human-system interface (HSI) of the main control room. The goal of this study is to describe the planning and methodology used for the HSI interface design. The products of this process are the layout specifications of the Control Room and the screens specifications for control software. (author)

Insights into structural and dynamical features of water at halloysite interfaces probed by DFT and classical molecular dynamics simulations.

Science.gov (United States)

Presti, Davide; Pedone, Alfonso; Mancini, Giordano; Duce, Celia; Tiné, Maria Rosaria; Barone, Vincenzo

2016-01-21

Density functional theory calculations and classical molecular dynamics simulations have been used to investigate the structure and dynamics of water molecules on kaolinite surfaces and confined in the interlayer of a halloysite model of nanometric dimension. The first technique allowed us to accurately describe the structure of the tetrahedral-octahedral slab of kaolinite in vacuum and in interaction with water molecules and to assess the performance of two widely employed empirical force fields to model water/clay interfaces. Classical molecular dynamics simulations were used to study the hydrogen bond network structure and dynamics of water adsorbed on kaolinite surfaces and confined in the halloysite interlayer. The results are in nice agreement with the few experimental data available in the literature, showing a pronounced ordering and reduced mobility of water molecules at the hydrophilic octahedral surfaces of kaolinite and confined in the halloysite interlayer, with respect to water interacting with the hydrophobic tetrahedral surfaces and in the bulk. Finally, this investigation provides new atomistic insights into the structural and dynamical properties of water-clay interfaces, which are of fundamental importance for both natural processes and industrial applications.

EPICS system: system structure and user interface

International Nuclear Information System (INIS)

West, R.E.; Bartlett, J.F.; Bobbitt, J.S.; Lahey, T.E.; Kramper, B.J.; MacKinnon, B.A.

1984-02-01

This paper present the user's view of and the general organization of the EPICS control system at Fermilab. Various subsystems of the EPICS control system are discussed. These include the user command language, software protection, the device database, remote computer interfaces, and several application utilities. This paper is related to two other papers on EPICS: an overview paper and a detailed implementation paper

Design and characterization of pentacene-inorganic interfaces

International Nuclear Information System (INIS)

Evans, Paul G.; Park, Byoungnam; Seo, Soonjoo; Zwickey, Jodi; In, Insik; Paoprasert, Peerasak; Gopalan, Padma

2007-01-01

The accumulation layer of organic thin film field-effect transistors extends away from the gate insulator/semiconductor interface by only a few molecular layers into the semiconductor thin film. The structure of these first few layers are thus crucially important to the electrical properties of devices and to the design of other functional structures incorporating organic/inorganic interfaces. We have used scanning tunneling microscopy to image the vacancies and grain boundaries in pentacene thin films on Si (0 0 1) substrates chemically terminated by styrene. The styrene termination allows pentacene molecules to form in a crystal structure similar to that of pentacene layers on the insulating substrates. In addition, by incorporating specially designed molecular monolayers at the interface between the gate insulator and the pentacene thin film, it is possible to form novel photoinduced charge-transfer structures. Tuning the chemical properties of the self-assembled monolayers affords a new degree of control in tuning the properties of these devices

User interface for a tele-operated robotic hand system

Energy Technology Data Exchange (ETDEWEB)

Crawford, Anthony L

2015-03-24

Disclosed here is a user interface for a robotic hand. The user interface anchors a user's palm in a relatively stationary position and determines various angles of interest necessary for a user's finger to achieve a specific fingertip location. The user interface additionally conducts a calibration procedure to determine the user's applicable physiological dimensions. The user interface uses the applicable physiological dimensions and the specific fingertip location, and treats the user's finger as a two link three degree-of-freedom serial linkage in order to determine the angles of interest. The user interface communicates the angles of interest to a gripping-type end effector which closely mimics the range of motion and proportions of a human hand. The user interface requires minimal contact with the operator and provides distinct advantages in terms of available dexterity, work space flexibility, and adaptability to different users.

High thermal stability of abrupt SiO2/GaN interface with low interface state density

Science.gov (United States)

Truyen, Nguyen Xuan; Taoka, Noriyuki; Ohta, Akio; Makihara, Katsunori; Yamada, Hisashi; Takahashi, Tokio; Ikeda, Mitsuhisa; Shimizu, Mitsuaki; Miyazaki, Seiichi

2018-04-01

The effects of postdeposition annealing (PDA) on the interface properties of a SiO2/GaN structure formed by remote oxygen plasma-enhanced chemical vapor deposition (RP-CVD) were systematically investigated. X-ray photoelectron spectroscopy clarified that PDA in the temperature range from 600 to 800 °C has almost no effects on the chemical bonding features at the SiO2/GaN interface, and that positive charges exist at the interface, the density of which can be reduced by PDA at 800 °C. The capacitance-voltage (C-V) and current density-SiO2 electric field characteristics of the GaN MOS capacitors also confirmed the reduction in interface state density (D it) and the improvement in the breakdown property of the SiO2 film after PDA at 800 °C. Consequently, a high thermal stability of the SiO2/GaN structure with a low fixed charge density and a low D it formed by RP-CVD was demonstrated. This is quite informative for realizing highly robust GaN power devices.

User Interface Design to Bring Simulation Data into the Classroom

International Nuclear Information System (INIS)

Tebbe, P.A.

1999-01-01

The training and simulation staff at the AmerenUE Callaway nuclear plant has been given the task of implementing the plant full-scope simulator in a classroom setting. As part of this project, members of the Nuclear Engineering Program at the University of Missouri, Columbia are working with plant personnel to create desktop software for use in training on fundamental plant principles. Data are created with the same modeling software used to power the simulator and are made available with the existing dynamic database structure. Visualization is provided through a specially designed user interface, created with the G programming language of LabVIEW. It is hoped that by focusing on a specific topic and designing the interface with educational objectives in mind, this software will help provide operators with an improved understanding of fundamental principles

Is Neural Activity Detected by ERP-Based Brain-Computer Interfaces Task Specific?

Directory of Open Access Journals (Sweden)

Markus A Wenzel

Full Text Available Brain-computer interfaces (BCIs that are based on event-related potentials (ERPs can estimate to which stimulus a user pays particular attention. In typical BCIs, the user silently counts the selected stimulus (which is repeatedly presented among other stimuli in order to focus the attention. The stimulus of interest is then inferred from the electroencephalogram (EEG. Detecting attention allocation implicitly could be also beneficial for human-computer interaction (HCI, because it would allow software to adapt to the user's interest. However, a counting task would be inappropriate for the envisaged implicit application in HCI. Therefore, the question was addressed if the detectable neural activity is specific for silent counting, or if it can be evoked also by other tasks that direct the attention to certain stimuli.Thirteen people performed a silent counting, an arithmetic and a memory task. The tasks required the subjects to pay particular attention to target stimuli of a random color. The stimulus presentation was the same in all three tasks, which allowed a direct comparison of the experimental conditions.Classifiers that were trained to detect the targets in one task, according to patterns present in the EEG signal, could detect targets in all other tasks (irrespective of some task-related differences in the EEG.The neural activity detected by the classifiers is not strictly task specific but can be generalized over tasks and is presumably a result of the attention allocation or of the augmented workload. The results may hold promise for the transfer of classification algorithms from BCI research to implicit relevance detection in HCI.

Energy level alignment at interfaces in organic photovoltaic devices

International Nuclear Information System (INIS)

Opitz, Andreas; Frisch, Johannes; Schlesinger, Raphael; Wilke, Andreas; Koch, Norbert

2013-01-01

Highlights: ► Energy level alignment is crucial for organic solar cell efficiency. ► Photoelectron spectroscopy can reliably determine energy levels of organic material interfaces. ► Care must be taken to avoid even subtle sample damage. -- Abstract: The alignment of energy levels at interfaces in organic photovoltaic devices is crucial for their energy conversion efficiency. Photoelectron spectroscopy (PES) is a well-established and widely used technique for determining the electronic structure of materials; at the same time PES measurements of conjugated organic materials often pose significant challenges, such as obtaining sufficiently defined sample structures and radiation-induced damage of the organic layers. Here we report how these challenges can be tackled to unravel the energy levels at interfaces in organic photovoltaic devices, i.e., electrode/organic and organic/organic interfaces. The electronic structure across entire photovoltaic multilayer devices can thus be reconciled. Finally, general considerations for correlating the electronic structure and the photovoltaic performance of devices will be discussed

An object-oriented scripting interface to a legacy electronic structure code

DEFF Research Database (Denmark)

Bahn, Sune Rastad; Jacobsen, Karsten Wedel

2002-01-01

The authors have created an object-oriented scripting interface to a mature density functional theory code. The interface gives users a high-level, flexible handle on the code without rewriting the underlying number-crunching code. The authors also discuss design issues and the advantages...

Study of Direct-Contact HfO2/Si Interfaces

Directory of Open Access Journals (Sweden)

Noriyuki Miyata

2012-03-01

Full Text Available Controlling monolayer Si oxide at the HfO2/Si interface is a challenging issue in scaling the equivalent oxide thickness of HfO2/Si gate stack structures. A concept that the author proposes to control the Si oxide interface by using ultra-high vacuum electron-beam HfO2 deposition is described in this review paper, which enables the so-called direct-contact HfO2/Si structures to be prepared. The electrical characteristics of the HfO2/Si metal-oxide-semiconductor capacitors are reviewed, which suggest a sufficiently low interface state density for the operation of metal-oxide-semiconductor field-effect-transistors (MOSFETs but reveal the formation of an unexpected strong interface dipole. Kelvin probe measurements of the HfO2/Si structures provide obvious evidence for the formation of dipoles at the HfO2/Si interfaces. The author proposes that one-monolayer Si-O bonds at the HfO2/Si interface naturally lead to a large potential difference, mainly due to the large dielectric constant of the HfO2. Dipole scattering is demonstrated to not be a major concern in the channel mobility of MOSFETs.

A estrutura da representação social da morte na interface com as religiosidades em equipes multiprofissionais de saúde The structure of social representation of death in the interface with the religiosities of healthcare professionals groups

Directory of Open Access Journals (Sweden)

Alexsandro Medeiros do Nascimento

2007-01-01

Full Text Available O estudo objetivou acessar a estrutura da representação social da morte em equipes multiprofissionais de saúde na interface com a religiosidade, no que esta interfere nas significações atribuídas à morte por esta população em específico. Utilizou-se um instrumento com questões abertas e fechadas sobre a morte e o morrer, bem como sobre a vivência religiosa singular dos participantes. Protocolos escritos foram capturados em uma amostra de 80 profissionais (49 médicos, 13 psicólogas, 18 enfermeiras pertencentes a 10 equipes multiprofissionais de saúde. Estes foram analisados através de Análise de Conteúdo e de Análise de Estrutura de Similaridade (SSA e interpretados pela Teoria das Representações Sociais. Os dados revelaram uma interferência expressiva das crenças religiosas na estruturação da representação da Morte.The study aims to investigate the structure of social representation of death in a Healthcare professional group establishing an interface with religiosity and how the latter interferes in the meaning attributed to death by this specific population. Open and closed questions on death or the act of dying, and on the singular religious experience of the participants were applied. Written protocols were collected from a sample of 80 professionals (49 physicians, 13 psychologists, and 18 nurses, which were analyzed according to content analysis and non-metric multidimensional analysis, SSA (Similarity Structure Analysis, and interpreted according to the theory of Social Representations, revealing a significant interference of religious believes in the structure of death representation.

Liquid crystal interfaces: Experiments, simulations and biosensors

Science.gov (United States)

Popov, Piotr

Interfacial phenomena are ubiquitous and extremely important in various aspects of biological and industrial processes. For example, many liquid crystal applications start by alignment with a surface. The underlying mechanisms of the molecular organization of liquid crystals at an interface are still under intensive study and continue to be important to the display industry in order to develop better and/or new display technology. My dissertation research has been devoted to studying how complex liquid crystals can be guided to organize at an interface, and to using my findings to develop practical applications. Specifically, I have been working on developing biosensors using liquid-crystal/surfactant/lipid/protein interactions as well as the alignment of low-symmetry liquid crystals for potential new display and optomechanical applications. The biotechnology industry needs better ways of sensing biomaterials and identifying various nanoscale events at biological interfaces and in aqueous solutions. Sensors in which the recognition material is a liquid crystal naturally connects the existing knowledge and experience of the display and biotechnology industries together with surface and soft matter sciences. This dissertation thus mainly focuses on the delicate phenomena that happen at liquid interfaces. In the introduction, I start by defining the interface and discuss its structure and the relevant interfacial forces. I then introduce the general characteristics of biosensors and, in particular, describe the design of biosensors that employ liquid crystal/aqueous solution interfaces. I further describe the basic properties of liquid crystal materials that are relevant for liquid crystal-based biosensing applications. In CHAPTER 2, I describe the simulation methods and experimental techniques used in this dissertation. In CHAPTER 3 and CHAPTER 4, I present my computer simulation work. CHAPTER 3 presents insight of how liquid crystal molecules are aligned by

Network device interface for digitally interfacing data channels to a controller via a network

Science.gov (United States)

Ellerbrock, Philip J. (Inventor); Grant, Robert L. (Inventor); Konz, Daniel W. (Inventor); Winkelmann, Joseph P. (Inventor)

2009-01-01

A communications system and method are provided for digitally connecting a plurality of data channels, such as sensors, actuators, and subsystems, to a controller using a network bus. The network device interface interprets commands and data received from the controller and polls the data channels in accordance with these commands. Specifically, the network device interface receives digital commands and data from the controller, and based on these commands and data, communicates with the data channels to either retrieve data in the case of a sensor or send data to activate an actuator. Data retrieved from the sensor is converted into digital signals and transmitted to the controller. Network device interfaces associated with different data channels can coordinate communications with the other interfaces based on either a transition in a command message sent by the bus controller or a synchronous clock signal.

Synchrotron-based photoemission study of electronic structure of the Cs/GaN ultrathin interface

Science.gov (United States)

Benemanskaya, G. V.; Kukushkin, S. A.; Dementev, P. A.; Lapushkin, M. N.; Timoshnev, S. N.; Smirnov, D. V.

2018-03-01

Electronic structure of the Cs/n-GaN nano-interface has been studied in situ via synchrotron-based photoelectron spectroscopy by excitation in the energy range of 70-400 eV. The GaN sample was grown by an original method of epitaxy of low-defect unstressed nanoscaled films on AlGaN/SiC/Si substrate. Changes in the surface state spectra and in the Ga 3d, Cs 4d, Cs 5p, N 1s core level spectra have been revealed under different cesium coverages. The intrinsic surface states for the clean GaN surface at binding energies of ∼5.0 eV and ∼7.0 eV are attenuated during Cs adsorption. Simultaneously three Cs induced surface states are found to arise. Drastic changes in the surface state spectrum were ascertained and shown to be originated from the local interacting Ga dangling bonds and adsorbed Cs atoms initiating the electron redistribution effect with formation of the semiconductor-like Cs/n-GaN interface.

Determinants of user acceptance of a specific social platform for older adults: An empirical examination of user interface characteristics and behavioral intention.

Directory of Open Access Journals (Sweden)

Tsai-Hsuan Tsai

Full Text Available The use of the Internet and social applications has many benefits for the elderly, but numerous investigations have shown that the elderly do not perceive online social networks as a friendly social environment. Therefore, TreeIt, a social application specifically designed for the elderly, was developed for this study. In the TreeIt application, seven mechanisms promoting social interaction were designed to allow older adults to use social networking sites (SNSs to increase social connection, maintain the intensity of social connections and strengthen social experience. This study's main objective was to investigate how user interface design affects older people's intention and attitude related to using SNSs. Fourteen user interface evaluation heuristics proposed by Zhang et al. were adopted as the criteria to assess user interface usability and further grouped into three categories: system support, user interface design and navigation. The technology acceptance model was adopted to assess older people's intention and attitude related to using SNSs. One hundred and one elderly persons were enrolled in this study as subjects, and the results showed that all of the hypotheses proposed in this study were valid: system support and perceived usefulness had a significant effect on behavioral intention; user interface design and perceived ease of use were positively correlated with perceived usefulness; and navigation exerted an influence on perceived ease of use. The results of this study are valuable for the future development of social applications for the elderly.

Determinants of user acceptance of a specific social platform for older adults: An empirical examination of user interface characteristics and behavioral intention.

Science.gov (United States)

Tsai, Tsai-Hsuan; Chang, Hsien-Tsung; Chen, Yan-Jiun; Chang, Yung-Sheng

2017-01-01

The use of the Internet and social applications has many benefits for the elderly, but numerous investigations have shown that the elderly do not perceive online social networks as a friendly social environment. Therefore, TreeIt, a social application specifically designed for the elderly, was developed for this study. In the TreeIt application, seven mechanisms promoting social interaction were designed to allow older adults to use social networking sites (SNSs) to increase social connection, maintain the intensity of social connections and strengthen social experience. This study's main objective was to investigate how user interface design affects older people's intention and attitude related to using SNSs. Fourteen user interface evaluation heuristics proposed by Zhang et al. were adopted as the criteria to assess user interface usability and further grouped into three categories: system support, user interface design and navigation. The technology acceptance model was adopted to assess older people's intention and attitude related to using SNSs. One hundred and one elderly persons were enrolled in this study as subjects, and the results showed that all of the hypotheses proposed in this study were valid: system support and perceived usefulness had a significant effect on behavioral intention; user interface design and perceived ease of use were positively correlated with perceived usefulness; and navigation exerted an influence on perceived ease of use. The results of this study are valuable for the future development of social applications for the elderly.

Determinants of user acceptance of a specific social platform for older adults: An empirical examination of user interface characteristics and behavioral intention

Science.gov (United States)

Chang, Hsien-Tsung; Chen, Yan-Jiun; Chang, Yung-Sheng

2017-01-01

The use of the Internet and social applications has many benefits for the elderly, but numerous investigations have shown that the elderly do not perceive online social networks as a friendly social environment. Therefore, TreeIt, a social application specifically designed for the elderly, was developed for this study. In the TreeIt application, seven mechanisms promoting social interaction were designed to allow older adults to use social networking sites (SNSs) to increase social connection, maintain the intensity of social connections and strengthen social experience. This study’s main objective was to investigate how user interface design affects older people’s intention and attitude related to using SNSs. Fourteen user interface evaluation heuristics proposed by Zhang et al. were adopted as the criteria to assess user interface usability and further grouped into three categories: system support, user interface design and navigation. The technology acceptance model was adopted to assess older people’s intention and attitude related to using SNSs. One hundred and one elderly persons were enrolled in this study as subjects, and the results showed that all of the hypotheses proposed in this study were valid: system support and perceived usefulness had a significant effect on behavioral intention; user interface design and perceived ease of use were positively correlated with perceived usefulness; and navigation exerted an influence on perceived ease of use. The results of this study are valuable for the future development of social applications for the elderly. PMID:28837566

Electrical and photoelectric properties of Si-based metal–insulator–semiconductor structures with Au nanoparticles at the insulator–semiconductor interface

Energy Technology Data Exchange (ETDEWEB)

Koryazhkina, M. N., E-mail: mahavenok@mail.ru; Tikhov, S. V.; Gorshkov, O. N.; Kasatkin, A. P.; Antonov, I. N. [Lobachevsky State University of Nizhny Novgorod (NNSU) (Russian Federation)

2016-12-15

It is shown that the formation of Au nanoparticles at the insulator–silicon interface in structures with a high density of surface states results in a shift of the Fermi-level pinning energy at this interface towards the valence-band ceiling in silicon and in increasing the surface-state density at energies close to the Fermi level. In this case, a band with a peak at 0.85 eV arises on the photosensivity curves of the capacitor photovoltage, which is explained by the photoemission of electrons from the formed Au-nanoparticle electron states near the valence-band ceiling in silicon.

Influence of the solid-gas interface on the effective thermal parameters of a two-layer structure in photoacoustic experiments

International Nuclear Information System (INIS)

Aguirre, N Munoz; Perez, L MartInez; Garibay-Febles, V; Lozada-Cassou, M

2004-01-01

From the theoretical point of view, the influence of the solid-gas interface on the effective thermal parameters in a two-layer structure of the photoacoustic technique is discussed. It is shown that the effective thermal parameters depend strongly upon the thermal resistance value associated with the solid-gas interface. New expressions for the effective thermal conductivity and thermal diffusivity in the low frequency limit are obtained. In the high frequency limit, the 'resonant' behaviour of the effective thermal diffusivity is maintained and a new complex dependence on frequency of the effective thermal conductivity is shown

Atomic and electronic structure of doped Si (111 ) (2 √{3 }×2 √{3 }) R 30∘ -Sn interfaces

Science.gov (United States)

Yi, Seho; Ming, Fangfei; Huang, Ying-Tzu; Smith, Tyler S.; Peng, Xiyou; Tu, Weisong; Mulugeta, Daniel; Diehl, Renee D.; Snijders, Paul C.; Cho, Jun-Hyung; Weitering, Hanno H.

2018-05-01

The hole-doped Si (111 ) (2 √ 3 ×2 √ 3 ) R 30∘ -Sn interface exhibits a symmetry-breaking insulator-insulator transition below 100 K that appears to be triggered by electron tunneling into the empty surface-state bands. No such transition is seen in electron-doped systems. To elucidate the nature and driving force of this phenomenon, the structure of the interface must be resolved. Here we report on an extensive experimental and theoretical study, including scanning tunneling microscopy and spectroscopy (STM/STS), dynamical low-energy electron diffraction (LEED) analysis, and density functional theory (DFT) calculations, to elucidate the structure of this interface. We consider six different structure models, three of which have been proposed before, and conclude that only two of them can account for the majority of experimental data. One of them is the model according to Törnevik et al. [C. Törnevik et al., Phys. Rev. B 44, 13144 (1991), 10.1103/PhysRevB.44.13144] with a total Sn coverage of 14/12 monolayers (ML). The other is the "revised trimer model" with a total Sn coverage of 13/12 ML, introduced in this work. These two models are very difficult to discriminate on the basis of DFT or LEED alone, but STS data clearly point toward the Törnevik model as the most viable candidate among the models considered here. The STS data also provide additional insights regarding the electron-injection-driven phase transformation. Similar processes may occur at other metal/semiconductor interfaces, provided they are nonmetallic and can be doped. This could open up a new pathway toward the creation of novel surface phases with potentially very interesting and desirable electronic properties.

Porphyrins at interfaces

Science.gov (United States)

Auwärter, Willi; Écija, David; Klappenberger, Florian; Barth, Johannes V.

2015-02-01

Porphyrins and other tetrapyrrole macrocycles possess an impressive variety of functional properties that have been exploited in natural and artificial systems. Different metal centres incorporated within the tetradentate ligand are key for achieving and regulating vital processes, including reversible axial ligation of adducts, electron transfer, light-harvesting and catalytic transformations. Tailored substituents optimize their performance, dictating their arrangement in specific environments and mediating the assembly of molecular nanoarchitectures. Here we review the current understanding of these species at well-defined interfaces, disclosing exquisite insights into their structural and chemical properties, and also discussing methods by which to manipulate their intramolecular and organizational features. The distinct characteristics arising from the interfacial confinement offer intriguing prospects for molecular science and advanced materials. We assess the role of surface interactions with respect to electronic and physicochemical characteristics, and describe in situ metallation pathways, molecular magnetism, rotation and switching. The engineering of nanostructures, organized layers, interfacial hybrid and bio-inspired systems is also addressed.

Capillary-wave dynamics and interface structure modulation in binary Bose-Einstein condensate mixtures

Science.gov (United States)

Indekeu, Joseph O.; Van Thu, Nguyen; Lin, Chang-You; Phat, Tran Huu

2018-04-01

The localized low-energy interfacial excitations, or interfacial Nambu-Goldstone modes, of phase-segregated binary mixtures of Bose-Einstein condensates are investigated analytically. To this end a double-parabola approximation (DPA) is performed on the Lagrangian density in Gross-Pitaevskii theory for a system in a uniform potential. This DPA entails a model in which analytic expressions are obtained for the excitations underlying capillary waves or ripplons for arbitrary strength K (>1 ) of the phase segregation. The dispersion relation ω (k ) ∝k3 /2 is derived directly from the Bogoliubov-de Gennes equations in the limit that the wavelength 2 π /k is much larger than the interface width. The proportionality constant in the dispersion relation provides the static interfacial tension. A correction term in ω (k ) of order k5 /2 is calculated analytically within the DPA model. The combined result is tested against numerical diagonalization of the exact Bogoliubov-de Gennes equations. Satisfactory agreement is obtained in the range of physically relevant wavelengths. The ripplon dispersion relation is relevant to state-of-the-art experiments using (quasi)uniform optical-box traps. Furthermore, within the DPA model explicit expressions are obtained for the structural deformation of the interface due to the passing of the capillary wave. It is found that the amplitude of the wave is enhanced by an amount that is quadratic in the ratio of the phase velocity ω /k to the sound velocity c . For generic mixtures consisting of condensates with unequal healing lengths, an additional modulation is predicted of the common value of the condensate densities at the interface.

Electrochemical impedance spectroscopy for quantitative interface state characterization of planar and nanostructured semiconductor-dielectric interfaces

Science.gov (United States)

Meng, Andrew C.; Tang, Kechao; Braun, Michael R.; Zhang, Liangliang; McIntyre, Paul C.

2017-10-01

The performance of nanostructured semiconductors is frequently limited by interface defects that trap electronic carriers. In particular, high aspect ratio geometries dramatically increase the difficulty of using typical solid-state electrical measurements (multifrequency capacitance- and conductance-voltage testing) to quantify interface trap densities (D it). We report on electrochemical impedance spectroscopy (EIS) to characterize the energy distribution of interface traps at metal oxide/semiconductor interfaces. This method takes advantage of liquid electrolytes, which provide conformal electrical contacts. Planar Al2O3/p-Si and Al2O3/p-Si0.55Ge0.45 interfaces are used to benchmark the EIS data against results obtained from standard electrical testing methods. We find that the solid state and EIS data agree very well, leading to the extraction of consistent D it energy distributions. Measurements carried out on pyramid-nanostructured p-Si obtained by KOH etching followed by deposition of a 10 nm ALD-Al2O3 demonstrate the application of EIS to trap characterization of a nanostructured dielectric/semiconductor interface. These results show the promise of this methodology to measure interface state densities for a broad range of semiconductor nanostructures such as nanowires, nanofins, and porous structures.

Interface Engineering with MoS2 -Pd Nanoparticles Hybrid Structure for a Low Voltage Resistive Switching Memory.

Science.gov (United States)

Wang, Xue-Feng; Tian, He; Zhao, Hai-Ming; Zhang, Tian-Yu; Mao, Wei-Quan; Qiao, Yan-Cong; Pang, Yu; Li, Yu-Xing; Yang, Yi; Ren, Tian-Ling

2018-01-01

Metal oxide-based resistive random access memory (RRAM) has attracted a lot of attention for its scalability, temperature robustness, and potential to achieve machine learning. However, a thick oxide layer results in relatively high program voltage while a thin one causes large leakage current and a small window. Owing to these fundamental limitations, by optimizing the oxide layer itself a novel interface engineering idea is proposed to reduce the programming voltage, increase the uniformity and on/off ratio. According to this idea, a molybdenum disulfide (MoS 2 )-palladium nanoparticles hybrid structure is used to engineer the oxide/electrode interface of hafnium oxide (HfO x )-based RRAM. Through its interface engineering, the set voltage can be greatly lowered (from -3.5 to -0.8 V) with better uniformity under a relatively thick HfO x layer (≈15 nm), and a 30 times improvement of the memory window can be obtained. Moreover, due to the atomic thickness of MoS 2 film and high transmittance of ITO, the proposed RRAM exhibits high transparency in visible light. As the proposed interface-engineering RRAM exhibits good transparency, low SET voltage, and a large resistive switching window, it has huge potential in data storage in transparent circuits and wearable electronics with relatively low supply voltage. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Docking-based modeling of protein-protein interfaces for extensive structural and functional characterization of missense mutations.

Science.gov (United States)

Barradas-Bautista, Didier; Fernández-Recio, Juan

2017-01-01

Next-generation sequencing (NGS) technologies are providing genomic information for an increasing number of healthy individuals and patient populations. In the context of the large amount of generated genomic data that is being generated, understanding the effect of disease-related mutations at molecular level can contribute to close the gap between genotype and phenotype and thus improve prevention, diagnosis or treatment of a pathological condition. In order to fully characterize the effect of a pathological mutation and have useful information for prediction purposes, it is important first to identify whether the mutation is located at a protein-binding interface, and second to understand the effect on the binding affinity of the affected interaction/s. Computational methods, such as protein docking are currently used to complement experimental efforts and could help to build the human structural interactome. Here we have extended the original pyDockNIP method to predict the location of disease-associated nsSNPs at protein-protein interfaces, when there is no available structure for the protein-protein complex. We have applied this approach to the pathological interaction networks of six diseases with low structural data on PPIs. This approach can almost double the number of nsSNPs that can be characterized and identify edgetic effects in many nsSNPs that were previously unknown. This can help to annotate and interpret genomic data from large-scale population studies, and to achieve a better understanding of disease at molecular level.

Docking-based modeling of protein-protein interfaces for extensive structural and functional characterization of missense mutations.

Directory of Open Access Journals (Sweden)

Didier Barradas-Bautista

Full Text Available Next-generation sequencing (NGS technologies are providing genomic information for an increasing number of healthy individuals and patient populations. In the context of the large amount of generated genomic data that is being generated, understanding the effect of disease-related mutations at molecular level can contribute to close the gap between genotype and phenotype and thus improve prevention, diagnosis or treatment of a pathological condition. In order to fully characterize the effect of a pathological mutation and have useful information for prediction purposes, it is important first to identify whether the mutation is located at a protein-binding interface, and second to understand the effect on the binding affinity of the affected interaction/s. Computational methods, such as protein docking are currently used to complement experimental efforts and could help to build the human structural interactome. Here we have extended the original pyDockNIP method to predict the location of disease-associated nsSNPs at protein-protein interfaces, when there is no available structure for the protein-protein complex. We have applied this approach to the pathological interaction networks of six diseases with low structural data on PPIs. This approach can almost double the number of nsSNPs that can be characterized and identify edgetic effects in many nsSNPs that were previously unknown. This can help to annotate and interpret genomic data from large-scale population studies, and to achieve a better understanding of disease at molecular level.

Lineage-specific interface proteins match up the cell cycle and differentiation in embryo stem cells

DEFF Research Database (Denmark)

Re, Angela; Workman, Christopher; Waldron, Levi

2014-01-01

The shortage of molecular information on cell cycle changes along embryonic stem cell (ESC) differentiation prompts an in silico approach, which may provide a novel way to identify candidate genes or mechanisms acting in coordinating the two programs. We analyzed germ layer specific gene expression...... changes during the cell cycle and ESC differentiation by combining four human cell cycle transcriptome profiles with thirteen in vitro human ESC differentiation studies. To detect cross-talk mechanisms we then integrated the transcriptome data that displayed differential regulation with protein...... interaction data. A new class of non-transcriptionally regulated genes was identified, encoding proteins which interact systematically with proteins corresponding to genes regulated during the cell cycle or cell differentiation, and which therefore can be seen as interface proteins coordinating the two...

Experimental approaches for probing interfaces and grain boundaries

International Nuclear Information System (INIS)

Barrera, E.V.; Marcus, H.L.

1990-01-01

This paper focuses its attention on several research efforts performed by the authors and colleagues whose primary aim is probing interfacial and grain boundary properties. The first investigations described pertain to impurity segregation induced embrittlement which were modeled using thermodynamic considerations and were characterized by fracture testing using Auger electron spectroscopy (AES). Localized interface chemical characterization is essential in this research. The second investigation focuses on interface/impurity interaction determination. Extended X-Ray Absorption Fine Structure (EXAFS), a structure characterization tool, was used to determine the local environment of impurities in metal-impurity-metal laminate composites, where the impurities were in monolayer to submonolayer interface concentrations. The third study pertains to the interface fracture in metal-matrix (metal/metal oxide/graphite) composites where a correlation was made between electronic states and fracture path

Ion specific correlations in bulk and at biointerfaces

International Nuclear Information System (INIS)

Kalcher, I; Horinek, D; Netz, R R; Dzubiella, J

2009-01-01

Ion specific effects are ubiquitous in any complex colloidal or biological fluid in bulk or at interfaces. The molecular origins of these 'Hofmeister effects' are not well understood and their theoretical description poses a formidable challenge to the modeling and simulation community. On the basis of the combination of atomistically resolved molecular dynamics (MD) computer simulations and statistical mechanics approaches, we present a few selected examples of specific electrolyte effects in bulk, at simple neutral and charged interfaces, and on a short α-helical peptide. The structural complexity in these strongly Coulomb-correlated systems is highlighted and analyzed in the light of available experimental data. While in general the comparison of MD simulations to experiments often lacks quantitative agreement, mostly because molecular force fields and coarse-graining procedures remain to be optimized, the consensus as regards trends provides important insights into microscopic hydration and binding mechanisms.

Ion specific correlations in bulk and at biointerfaces.

Science.gov (United States)

Kalcher, I; Horinek, D; Netz, R R; Dzubiella, J

2009-10-21

Ion specific effects are ubiquitous in any complex colloidal or biological fluid in bulk or at interfaces. The molecular origins of these 'Hofmeister effects' are not well understood and their theoretical description poses a formidable challenge to the modeling and simulation community. On the basis of the combination of atomistically resolved molecular dynamics (MD) computer simulations and statistical mechanics approaches, we present a few selected examples of specific electrolyte effects in bulk, at simple neutral and charged interfaces, and on a short α-helical peptide. The structural complexity in these strongly Coulomb-correlated systems is highlighted and analyzed in the light of available experimental data. While in general the comparison of MD simulations to experiments often lacks quantitative agreement, mostly because molecular force fields and coarse-graining procedures remain to be optimized, the consensus as regards trends provides important insights into microscopic hydration and binding mechanisms.

Interfacial structure of soft matter probed by SFG spectroscopy.

Science.gov (United States)

Ye, Shen; Tong, Yujin; Ge, Aimin; Qiao, Lin; Davies, Paul B

2014-10-01

Sum frequency generation (SFG) vibrational spectroscopy, an interface-specific technique in contrast to, for example, attenuated total reflectance spectroscopy, which is only interface sensitive, has been employed to investigate the surface and interface structure of soft matter on a molecular scale. The experimental arrangement required to carry out SFG spectroscopy, with particular reference to soft matter, and the analytical methods developed to interpret the spectra are described. The elucidation of the interfacial structure of soft matter systems is an essential prerequisite in order to understand and eventually control the surface properties of these important functional materials. Copyright © 2014 The Chemical Society of Japan and Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Microsphere Wetting, Meniscus Structure, and Capillary Interactions on a Curved Liquid Interface

Science.gov (United States)

Kim, Paul; Dinsmore, Anthony; Hoagland, David; Russell, Thomas

A small spherical microparticle on a cylindrically curved liquid interface locally induces a quadrupolar interface deformation to maintain a constant contact angle about its wetted periphery. Measured by optical profilometry, this deformation was compared to a recent theoretical expression, and good agreement was noted for contact line shape, particle vertical position, and deformation vs. (distance, angle, particle size, interfacial curvature). Interface quadrupoles lead to particle capillary interactions in analogy to 2D electrostatic quadrupoles, and as one consequence, spheres on a cylindrical interface assemble tetragonally, i.e., into a square lattice. This assembly was monitored in the optical microscope, with particles interacting as predicted, into a square lattice aligned with the underlying cylindrical axis. These particles and assemblies were driven to the middle of the curved interface by capillary interaction with pinned liquid contact lines on each side of the liquid cylindrical section used in the experiments. These phenomena can inform the directed interfacial assembly of micro-sized spherical objects, with potential application in fabrication of functional devices and materials, encapsulation, and emulsification.

First Principles Simulation of a Ceramic/ Metal Interface with Misfit

International Nuclear Information System (INIS)

Benedek, R.; Alavi, A.; Seidman, D. N.; Yang, L. H.; Muller, D. A.; Woodward, C.

2000-01-01

The relaxed atomic structure of a model ceramic/metal interface, {222}MgO/Cu , is simulated, including lattice constant mismatch, using first principles local-density functional theory plane wave pseudopotential methods. The 399-atom computational unit cell contains 36 O and 49 Cu atoms per layer in accordance with the 7/6 ratio of MgO to Cu lattice constants. The atomic layers on both sides of the interface warp to optimize the local bonding. The interface adhesive energy is calculated. The interface electronic structure is found to vary appreciably with the local environment. (c) 2000 The American Physical Society

Systematic determination of the mosaic structure of bacterial genomes: species backbone versus strain-specific loops

Directory of Open Access Journals (Sweden)

Gendrault-Jacquemard A

2005-07-01

Full Text Available Abstract Background Public databases now contain multitude of complete bacterial genomes, including several genomes of the same species. The available data offers new opportunities to address questions about bacterial genome evolution, a task that requires reliable fine comparison data of closely related genomes. Recent analyses have shown, using pairwise whole genome alignments, that it is possible to segment bacterial genomes into a common conserved backbone and strain-specific sequences called loops. Results Here, we generalize this approach and propose a strategy that allows systematic and non-biased genome segmentation based on multiple genome alignments. Segmentation analyses, as applied to 13 different bacterial species, confirmed the feasibility of our approach to discern the 'mosaic' organization of bacterial genomes. Segmentation results are available through a Web interface permitting functional analysis, extraction and visualization of the backbone/loops structure of documented genomes. To illustrate the potential of this approach, we performed a precise analysis of the mosaic organization of three E. coli strains and functional characterization of the loops. Conclusion The segmentation results including the backbone/loops structure of 13 bacterial species genomes are new and available for use by the scientific community at the URL: http://genome.jouy.inra.fr/mosaic.

Actinides and environmental interfaces: striving for molecular-level understanding

International Nuclear Information System (INIS)

Heino Nitsche

2005-01-01

enhanced second harmonic generation can probe the electronic (UV-vis region) structure of metal species adsorbed at a surface or interface. Infrared-visible sum frequency generation spectroscopy probes the infrared vibrational spectrum of molecules adsorbed at the interface. SHG/SFG studies will greatly assist with understanding reactivity at interfaces of oxides and soil organic matter with heavy metals and radionuclides/actinides. Time-resolved Laser-fluorescence spectroscopy (TRLFS) is a highly sensitive tool for actinides that absorb light and de-excite by fluorescence emission, e.g., U(VI) and Cm(III), to probe changes in actinide speciation and coordination environment in solution. This method can also be used to differentiate whether adsorbed species form surface complexes or surface precipitates. Recently, it was shown that the intense synchrotron radiation can change the oxidation states of redox-sensitive actinide samples which may cause erroneous results, and low temperature measurements are now used to alleviate this shortcoming. X-ray Absorption Fine Structure (XAFS) Spectroscopy is composed of two component spectroscopies, X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) which provide element specific oxidation state and local structure information, respectively. EXAFS (Extended X-ray Absorption Fine Structure Spectroscopy) provides information on the chemical environment of particular actinide, in particular bond lengths and the number of neighboring atoms. Combining both methods, detailed knowledge of the different processes resulting from the interaction of the selected actinides with environmental interfaces can be gained. XANES and EXAFS measurements and TRLFS studies to obtain molecular-level mechanistic details of actinide interaction with common environmental solutions and interfaces will be presented together with first SHG/SFG characterization results of model systems for environmental interfaces

Non-uniform Solute Segregation at Semi-Coherent Metal/Oxide Interfaces

Science.gov (United States)

Choudhury, Samrat; Aguiar, Jeffery A.; Fluss, Michael J.; Hsiung, Luke L.; Misra, Amit; Uberuaga, Blas P.

2015-08-01

The properties and performance of metal/oxide nanocomposites are governed by the structure and chemistry of the metal/oxide interfaces. Here we report an integrated theoretical and experimental study examining the role of interfacial structure, particularly misfit dislocations, on solute segregation at a metal/oxide interface. We find that the local oxygen environment, which varies significantly between the misfit dislocations and the coherent terraces, dictates the segregation tendency of solutes to the interface. Depending on the nature of the solute and local oxygen content, segregation to misfit dislocations can change from attraction to repulsion, revealing the complex interplay between chemistry and structure at metal/oxide interfaces. These findings indicate that the solute chemistry at misfit dislocations is controlled by the dislocation density and oxygen content. Fundamental thermodynamic concepts - the Hume-Rothery rules and the Ellingham diagram - qualitatively predict the segregation behavior of solutes to such interfaces, providing design rules for novel interfacial chemistries.