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Sample records for surface enhanced coherent

  1. Nanophotonics with Surface Enhanced Coherent Raman Microscopy

    Science.gov (United States)

    Fast, Alexander

    Nonlinear nanophotonics is a rapidly developing field of research that aims at detecting and disentangling weak congested optical signatures on the nanoscale. Sub-wavelength field confinement of the local electromagnetic fields and the resulting field enhancement is achieved by utilizing plasmonic near-field antennas. This allows for probing nanoscopic volumes, a property unattainable by conventional far-field microscopy techniques. Combination of plasmonics and nonlinear optical microscopy provides a path to visualizing a small chemical and spatial subset of target molecules within an ensemble. This is achieved while maintaining rapid signal acquisition, which is necessary for capturing biological processes in living systems. Herein, a novel technique, wide-field surface enhanced coherent anti-Stokes Raman scattering (wfSE-CARS) is presented. This technique allows for isolating weak vibrational signals in nanoscopic proximity to the surface by using chemical sensitivity of coherent Raman microspectroscopy (CRM) and field confinement from surface plasmons supported on a thin gold film. Uniform field enhancement over a large field of view, achieved with surface plasmon polaritons (SPP) in wfSE-CARSS, allows for biomolecular imaging demonstrated on extended structures like phospholipid droplets and live cells. Surface selectivity and chemical contrast are achieved at 70 fJ/mum2 incident energy densities, which is over five orders of magnitude lower than used in conventional point scanning CRM. Next, a novel surface sensing imaging technique, local field induced metal emission (LFIME), is introduced. Presence of a sample material at the surface influences the local fields of a thin flat gold film, such that nonlinear fluorescence signal of the metal can be detected in the far-field. Nanoscale nonmetallic, nonfluorescent objects can be imaged with high signal-to-background ratio and diffraction limited lateral resolution using LFIME. Additionally, structure of the

  2. Coherent states and rational surfaces

    International Nuclear Information System (INIS)

    Brody, Dorje C; Graefe, Eva-Maria

    2010-01-01

    The state spaces of generalized coherent states associated with special unitary groups are shown to form rational curves and surfaces in the space of pure states. These curves and surfaces are generated by the various Veronese embeddings of the underlying state space into higher dimensional state spaces. This construction is applied to the parameterization of generalized coherent states, which is useful for practical calculations, and provides an elementary combinatorial approach to the geometry of the coherent state space. The results are extended to Hilbert spaces with indefinite inner products, leading to the introduction of a new kind of generalized coherent states.

  3. Coherent states and rational surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Brody, Dorje C; Graefe, Eva-Maria, E-mail: d.brody@imperial.ac.u [Department of Mathematics, Imperial College London, London SW7 2AZ (United Kingdom)

    2010-06-25

    The state spaces of generalized coherent states associated with special unitary groups are shown to form rational curves and surfaces in the space of pure states. These curves and surfaces are generated by the various Veronese embeddings of the underlying state space into higher dimensional state spaces. This construction is applied to the parameterization of generalized coherent states, which is useful for practical calculations, and provides an elementary combinatorial approach to the geometry of the coherent state space. The results are extended to Hilbert spaces with indefinite inner products, leading to the introduction of a new kind of generalized coherent states.

  4. Coherently Enhanced Wireless Power Transfer

    Science.gov (United States)

    Krasnok, Alex; Baranov, Denis G.; Generalov, Andrey; Li, Sergey; Alù, Andrea

    2018-04-01

    Extraction of electromagnetic energy by an antenna from impinging external radiation is at the basis of wireless communications and wireless power transfer (WPT). The maximum of transferred energy is ensured when the antenna is conjugately matched, i.e., when it is resonant and it has an equal coupling with free space and its load. This condition, however, can be easily affected by changes in the environment, preventing optimal operation of a WPT system. Here, we introduce the concept of coherently enhanced WPT that allows us to bypass this difficulty and achieve dynamic control of power transfer. The approach relies on coherent excitation of the waveguide connected to the antenna load with a backward propagating signal of specific amplitude and phase. This signal creates a suitable interference pattern at the load resulting in a modification of the local wave impedance, which in turn enables conjugate matching and a largely increased amount of extracted energy. We develop a simple theoretical model describing this concept, demonstrate it with full-wave numerical simulations for the canonical example of a dipole antenna, and verify experimentally in both near-field and far-field regimes.

  5. Spatial coherence profilometry on tilted surfaces

    Czech Academy of Sciences Publication Activity Database

    Pavlíček, Pavel; Halouzka, M.; Duan, Z.; Takeda, M.

    2009-01-01

    Roč. 48, č. 34 (2009), H40-H47 ISSN 0003-6935 R&D Projects: GA MŠk(CZ) 1M06002 Institutional research plan: CEZ:AV0Z10100522 Keywords : tilted surface * spatial coherence profilometry * spatial coherence * measurement error * shape measurement Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.410, year: 2009

  6. Enhanced delegated computing using coherence

    Science.gov (United States)

    Barz, Stefanie; Dunjko, Vedran; Schlederer, Florian; Moore, Merritt; Kashefi, Elham; Walmsley, Ian A.

    2016-03-01

    A longstanding question is whether it is possible to delegate computational tasks securely—such that neither the computation nor the data is revealed to the server. Recently, both a classical and a quantum solution to this problem were found [C. Gentry, in Proceedings of the 41st Annual ACM Symposium on the Theory of Computing (Association for Computing Machinery, New York, 2009), pp. 167-178; A. Broadbent, J. Fitzsimons, and E. Kashefi, in Proceedings of the 50th Annual Symposium on Foundations of Computer Science (IEEE Computer Society, Los Alamitos, CA, 2009), pp. 517-526]. Here, we study the first step towards the interplay between classical and quantum approaches and show how coherence can be used as a tool for secure delegated classical computation. We show that a client with limited computational capacity—restricted to an XOR gate—can perform universal classical computation by manipulating information carriers that may occupy superpositions of two states. Using single photonic qubits or coherent light, we experimentally implement secure delegated classical computations between an independent client and a server, which are installed in two different laboratories and separated by 50 m . The server has access to the light sources and measurement devices, whereas the client may use only a restricted set of passive optical devices to manipulate the information-carrying light beams. Thus, our work highlights how minimal quantum and classical resources can be combined and exploited for classical computing.

  7. Fringe pattern denoising using coherence-enhancing diffusion.

    Science.gov (United States)

    Wang, Haixia; Kemao, Qian; Gao, Wenjing; Lin, Feng; Seah, Hock Soon

    2009-04-15

    Electronic speckle pattern interferometry is one of the methods measuring the displacement on object surfaces in which fringe patterns need to be evaluated. Noise is one of the key problems affecting further processing and reducing measurement quality. We propose an application of coherence-enhancing diffusion to fringe-pattern denoising. It smoothes a fringe pattern along directions both parallel and perpendicular to fringe orientation with suitable diffusion speeds to more effectively reduce noise and improve fringe-pattern quality. It is a generalized work of Tang's et al.'s [Opt. Lett.33, 2179 (2008)] model that only smoothes a fringe pattern along fringe orientation. Since our model diffuses a fringe pattern with an additional direction, it is able to denoise low-density fringes as well as improve denoising effectiveness for high-density fringes. Theoretical analysis as well as simulation and experimental verifications are addressed.

  8. Ultrafast Coherent Control and Characterization of Surface Reactions using FELs

    CERN Document Server

    Ogasawara, Hirohito; Nordlund, Dennis

    2005-01-01

    The microscopic understanding of surface chemistry requires a detailed understanding of the dynamics of elementary processes at surfaces. The ultrashort electron pulse obtained in the linear accelerator to feed the FEL can be used for generation of coherent synchrotron radiation in the low energy THz regime. With the current parameters for LCLS this corresponds to radiation with energy corresponding to excitations of low-energy vibrational modes of molecules on surfaces or phonons in substrates. The coherent radiation can coherently manipulate atoms or molecules on surfaces. In this respect a chemical reaction can be initiated by coherent atomic motion along a specific reaction coordinate. Since the THz radiation is generated from the same source as the FEL radiation full-time synchronization for pump-probe experiments will be possible. The possibility to perform time-resolved X-ray Emission Spectroscopy (XES) and X-ray Photoelectron Spectroscopy (XPS) measurements as a probe of chemical dynamics is an exciti...

  9. Enhanced coherent undulator radiation from bunched electron beams

    International Nuclear Information System (INIS)

    Berryman, K.W.; Crosson, E.R.; Ricci, K.N.; Smith, T.I.

    1996-01-01

    When energetic bunches of electrons traverse an undulator field, they can spontaneously emit radiation both coherently and incoherently. Although it has generally been assumed that undulator radiation is incoherent at wavelengths short compared to the longitudinal size of the electron bunch, several recent observations have proved this assumption false. Furthermore, the appearance of coherent radiation is often accompanied by a significant increase in radiated power. Here we report observations of strongly enhanced coherent spontaneous radiation together with direct measurements, using transition radiation techniques, of the electron distributions responsible for the coherent emission. We also report demonstrated enhancements in the predicted spontaneous radiated power by as much as 6x10 4 using electron bunch compression. copyright 1996 American Institute of Physics

  10. Coherence enhanced quantum metrology in a nonequilibrium optical molecule

    Science.gov (United States)

    Wang, Zhihai; Wu, Wei; Cui, Guodong; Wang, Jin

    2018-03-01

    We explore the quantum metrology in an optical molecular system coupled to two environments with different temperatures, using a quantum master equation beyond secular approximation. We discover that the steady-state coherence originating from and sustained by the nonequilibrium condition can enhance quantum metrology. We also study the quantitative measures of the nonequilibrium condition in terms of the curl flux, heat current and entropy production at the steady state. They are found to grow with temperature difference. However, an apparent paradox arises considering the contrary behaviors of the steady-state coherence and the nonequilibrium measures in relation to the inter-cavity coupling strength. This paradox is resolved by decomposing the heat current into a population part and a coherence part. Only the latter, the coherence part of the heat current, is tightly connected to the steady-state coherence and behaves similarly with respect to the inter-cavity coupling strength. Interestingly, the coherence part of the heat current flows from the low-temperature reservoir to the high-temperature reservoir, opposite to the direction of the population heat current. Our work offers a viable way to enhance quantum metrology for open quantum systems through steady-state coherence sustained by the nonequilibrium condition, which can be controlled and manipulated to maximize its utility. The potential applications go beyond quantum metrology and extend to areas such as device designing, quantum computation and quantum technology in general.

  11. Wide-band coherent receiver development for enhanced surveillance

    International Nuclear Information System (INIS)

    Simpson, M.L.; Richards, R.K.; Hutchinson, D.P.

    1998-03-01

    Oak Ridge National Laboratory (ORNL) has been developing advanced coherent IR heterodyne receivers for plasma diagnostics in fusion reactors for over 20 years. Recent progress in wide band IR detectors and high speed electronics has significantly enhanced the measurement capabilities of coherent receivers. In addition, developments in new HgCdTe and quantum well IR photodetector (QWIP) focal plane arrays are providing the possibility of both active and passive coherent imaging. In this paper the authors discuss the implications of these new enabling technologies to the IR remote sensing community for enhanced surveillance. Coherent receivers, as opposed to direct or thermal detection, provide multiple dimensions of information about a scene or target in a single detector system. Combinations of range, velocity, temperature, and chemical species information are all available from a coherent heterodyne receiver. They present laboratory data showing measured noise equivalent power (NEP) of new QWIP detectors with heterodyne bandwidths greater than 7 GHz. For absorption measurements, a wide band coherent receiver provides the capability of looking between CO 2 lines at off-resonance peaks and thus the measurement of lines normally inaccessible with conventional heterodyne or direct detection systems. Also described are differential absorption lidar (DIAL) and Doppler laboratory measurements using an 8 x 8 HgCdTe focal plane array demonstrating the snapshot capability of coherent receiver detector arrays for enhanced chemical plume and moving hardbody capture. Finally they discuss a variety of coherent receiver configurations that can suppress (or enhance) sensitivity of present active remote sensing systems to speckle, glint, and other measurement anomalies

  12. Neurofeedback training of alpha-band coherence enhances motor performance.

    Science.gov (United States)

    Mottaz, Anais; Solcà, Marco; Magnin, Cécile; Corbet, Tiffany; Schnider, Armin; Guggisberg, Adrian G

    2015-09-01

    Neurofeedback training of motor cortex activations with brain-computer interface systems can enhance recovery in stroke patients. Here we propose a new approach which trains resting-state functional connectivity associated with motor performance instead of activations related to movements. Ten healthy subjects and one stroke patient trained alpha-band coherence between their hand motor area and the rest of the brain using neurofeedback with source functional connectivity analysis and visual feedback. Seven out of ten healthy subjects were able to increase alpha-band coherence between the hand motor cortex and the rest of the brain in a single session. The patient with chronic stroke learned to enhance alpha-band coherence of his affected primary motor cortex in 7 neurofeedback sessions applied over one month. Coherence increased specifically in the targeted motor cortex and in alpha frequencies. This increase was associated with clinically meaningful and lasting improvement of motor function after stroke. These results provide proof of concept that neurofeedback training of alpha-band coherence is feasible and behaviorally useful. The study presents evidence for a role of alpha-band coherence in motor learning and may lead to new strategies for rehabilitation. Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  13. Surface enhanced Raman scattering

    CERN Document Server

    Furtak, Thomas

    1982-01-01

    In the course of the development of surface science, advances have been identified with the introduction of new diagnostic probes for analytical characterization of the adsorbates and microscopic structure of surfaces and interfaces. Among the most recently de­ veloped techniques, and one around which a storm of controversy has developed, is what has now been earmarked as surface enhanced Raman scattering (SERS). Within this phenomenon, molecules adsorbed onto metal surfaces under certain conditions exhibit an anomalously large interaction cross section for the Raman effect. This makes it possible to observe the detailed vibrational signature of the adsorbate in the ambient phase with an energy resolution much higher than that which is presently available in electron energy loss spectroscopy and when the surface is in contact with a much larger amount of material than that which can be tolerated in infrared absorption experiments. The ability to perform vibrational spectroscopy under these conditions would l...

  14. Surface plasmon enhanced LED

    OpenAIRE

    Vučković, Jelena; Lončar, Marko; Painter, Oskar; Scherer, Axel

    2000-01-01

    Summary form only given. We designed and fabricated an LED based on a thin semiconductor membrane (λ/2) with silver mirrors. A large spontaneous emission enhancement and a high modulation speed are obtainable due to the strong localization of the electromagnetic field in the microcavity. The coupling to surface plasmon modes which are subsequently scattered out by means of a grating is used to improve the extraction efficiency of the LED. The bottom mirror is thick and unpatterned. The top mi...

  15. Inducement and enhancement of multiple coherence resonances in ...

    Indian Academy of Sciences (India)

    JIANCHENG SHI

    2017-11-16

    Nov 16, 2017 ... Inducement and enhancement of multiple coherence resonances in unidirectionally coupled neural systems: Random and time-periodic coupling strength. JIANCHENG SHI, MIN LUO and CHUSHENG HUANG. ∗. College of Chemistry and Material Sciences, Guangxi Teachers Education University, ...

  16. Inducement and enhancement of multiple coherence resonances in ...

    Indian Academy of Sciences (India)

    The effect of cooperative coupling strength (CCS), i.e., random coupling strength and time-periodic coupling strength, on multiple coherence resonances in unidirectionally coupled neural system has been investigated. Results show that noise, frequency and amplitude play efficient roles for the enhancement of various ...

  17. Nonrelativistic electron bunch train for coherently enhanced terahertz radiation sources

    International Nuclear Information System (INIS)

    Li Yuelin; Kim, Kwang-Je

    2008-01-01

    We propose to generate a train of prebunched electron beams for producing coherently enhanced Smith-Purcell radiation [S. J. Smith and E. M. Purcell, Phys. Rev. 92, 1069 (1953)] in the terahertz wavelength range. In this scheme, a train of picosecond laser pulses is produced to drive a photoemission gun to generate a train of 50 keV electron pulses. The parameters are chosen so that the space-charge effect does not destroy the pulse time structure. Smith-Purcell radiation from the electron pulse train is enhanced due both to the short length of the individual electron bunch and to the repetitive structure of the beam. Example systems producing coherent terahertz power at about 1 mW are described

  18. Generalization of fewest-switches surface hopping for coherences

    Science.gov (United States)

    Tempelaar, Roel; Reichman, David R.

    2018-03-01

    Fewest-switches surface hopping (FSSH) is perhaps the most widely used mixed quantum-classical approach for the modeling of non-adiabatic processes, but its original formulation is restricted to (adiabatic) population terms of the quantum density matrix, leaving its implementations with an inconsistency in the treatment of populations and coherences. In this article, we propose a generalization of FSSH that treats both coherence and population terms on equal footing and which formally reduces to the conventional FSSH algorithm for the case of populations. This approach, coherent fewest-switches surface hopping (C-FSSH), employs a decoupling of population relaxation and pure dephasing and involves two replicas of the classical trajectories interacting with two active surfaces. Through extensive benchmark calculations of a spin-boson model involving a Debye spectral density, we demonstrate the potential of C-FSSH to deliver highly accurate results for a large region of parameter space. Its uniform description of populations and coherences is found to resolve incorrect behavior observed for conventional FSSH in various cases, in particular at low temperature, while the parameter space regions where it breaks down are shown to be quite limited. Its computational expenses are virtually identical to conventional FSSH.

  19. Long-range coherence revealed in entropy enhanced chemonuclear fusion

    International Nuclear Information System (INIS)

    Ikegami, Hidetsugu

    2005-02-01

    Rate enhancement up to a factor of 10 15 has been observed in the nuclear fusion 7 Li + 2 H -> 8 Be + n with some tens keV deuterons implanted in metallic Li liquid. The enhanced fusion was found to be followed by the break-up of 8 Be into unidirectionally emitted paired α-particles. This indicates that recoil momenta of α-particles are sustained coherently by bulk liquid atoms. These remarkable facts urge reconsideration for the mechanism of nuclear fusion through taking into account linked irreversible atomic process. In the nuclear stopping region of atomic collision electrons adjust smoothly to the nuclear - fusion reforming electronic configuration and the entropy producing linked irreversible atomic fusion Li + H -> Be operates resulting in chemo-nuclear fusion. Here macroscopically distinct parts become correlated and long-range coherence appears in the liquid. These aspects are reflected in the entropy enhancement of chemo-nuclear fusion similar to irreversible chemical reactions in liquids. The observation of unidirectional emission of paired a-particles is another evidence for the long-range coherence in the chemo-nuclear fusion

  20. Surface enhanced thermo lithography

    KAUST Repository

    Coluccio, Maria Laura

    2017-01-13

    We used electroless deposition to fabricate clusters of silver nanoparticles (NPs) on a silicon substrate. These clusters are plasmonics devices that induce giant electromagnetic (EM) field increments. When those EM field are absorbed by the metal NPs clusters generate, in turn, severe temperature increases. Here, we used the laser radiation of a conventional Raman set-up to transfer geometrical patterns from a template of metal NPs clusters into a layer of thermo sensitive Polyphthalaldehyde (PPA) polymer. Temperature profile on the devices depends on specific arrangements of silver nanoparticles. In plane temperature variations may be controlled with (i) high nano-meter spatial precision and (ii) single Kelvin temperature resolution on varying the shape, size and spacing of metal nanostructures. This scheme can be used to generate strongly localized heat amplifications for applications in nanotechnology, surface enhanced thermo-lithography (SETL), biology and medicine (for space resolved cell ablation and treatment), nano-chemistry.

  1. Ultrafast Coherent Control and Characterization of Surface Reactions using FELs

    International Nuclear Information System (INIS)

    Ogasawara, Hirohito

    2005-01-01

    The microscopic understanding of reactions at surfaces requires an in-depth knowledge of the dynamics of elementary processes on an ultrafast timescale. This can be accomplished using an ultrafast excitation to initiate a chemical reaction and then probe the progression of the reaction with an ultrashort x-ray pulse from the FEL. There is a great potential to use atom-specific spectroscopy involving core levels to probe the chemical nature, structure and bonding of species on surfaces. The ultrashort electron pulse obtained in the linear accelerator to feed the X-ray FEL can also be used for generation of coherent synchrotron radiation in the low energy THz regime to be used as a pump. This radiation has an energy close to the thermal excitations of low-energy vibrational modes of molecules on surfaces and phonons in substrates. The coherent THz radiation will be an electric field pulse with a certain direction that can collectively manipulate atoms or molecules on surfaces. In this respect a chemical reaction can be initiated by collective atomic motion along a specific reaction coordinate. If the coherent THz radiation is generated from the same source as the X-ray FEL radiation, full-time synchronization for pump-probe experiments will be possible. The combination of THz and X-ray spectroscopy could be a unique opportunity for FEL facilities to conduct ultrafast chemistry studies at surfaces

  2. Enhancing Coherent Light-Matter Interactions through Microcavity-Engineered Plasmonic Resonances

    Science.gov (United States)

    Peng, Pai; Liu, Yong-Chun; Xu, Da; Cao, Qi-Tao; Lu, Guowei; Gong, Qihuang; Xiao, Yun-Feng

    2017-12-01

    Quantum manipulation is challenging in localized-surface plasmon resonances (LSPRs) due to strong dissipations. To enhance quantum coherence, here we propose to engineer the electromagnetic environment of LSPRs by placing metallic nanoparticles (MNPs) in optical microcavities. An analytical quantum model is first built to describe the LSPR-microcavity interaction, revealing the significantly enhanced coherent radiation and the reduced incoherent dissipation. Furthermore, when a quantum emitter interacts with the LSPRs in the cavity-engineered environment, its quantum yield is enhanced over 40 times and the radiative power over one order of magnitude, compared to those in the vacuum environment. Importantly, the cavity-engineered MNP-emitter system can enter the strong coupling regime of cavity quantum electrodynamics, providing a promising platform for the study of quantum plasmonics, quantum information processing, precise sensing, and spectroscopy.

  3. Ultrafast surface-enhanced Raman spectroscopy.

    Science.gov (United States)

    Keller, Emily L; Brandt, Nathaniel C; Cassabaum, Alyssa A; Frontiera, Renee R

    2015-08-07

    Ultrafast surface-enhanced Raman spectroscopy (SERS) with pico- and femtosecond time resolution has the ability to elucidate the mechanisms by which plasmons mediate chemical reactions. Here we review three important technological advances in these new methodologies, and discuss their prospects for applications in areas including plasmon-induced chemistry and sensing at very low limits of detection. Surface enhancement, arising from plasmonic materials, has been successfully incorporated with stimulated Raman techniques such as femtosecond stimulated Raman spectroscopy (FSRS) and coherent anti-Stokes Raman spectroscopy (CARS). These techniques are capable of time-resolved measurement on the femtosecond and picosecond time scale and can be used to follow the dynamics of molecules reacting near plasmonic surfaces. We discuss the potential application of ultrafast SERS techniques to probe plasmon-mediated processes, such as H2 dissociation and solar steam production. Additionally, we discuss the possibilities for high sensitivity SERS sensing using these stimulated Raman spectroscopies.

  4. Precision metrology of NSTX surfaces using coherent laser radar ranging

    International Nuclear Information System (INIS)

    Kugel, H.W.; Loesser, D.; Roquemore, A. L.; Menon, M. M.; Barry, R. E.

    2000-01-01

    A frequency modulated Coherent Laser Radar ranging diagnostic is being used on the National Spherical Torus Experiment (NSTX) for precision metrology. The distance (range) between the 1.5 microm laser source and the target is measured by the shift in frequency of the linearly modulated beam reflected off the target. The range can be measured to a precision of < 100microm at distances of up to 22 meters. A description is given of the geometry and procedure for measuring NSTX interior and exterior surfaces during open vessel conditions, and the results of measurements are elaborated

  5. Temporal and Spectral Coherence From Rough Surface Scattering

    National Research Council Canada - National Science Library

    Gu, Zu-Han

    2006-01-01

    .... The enhanced backscattering is manifested by the presence of a well-defined peak in the retro-reflection direction in the angular distribution of the intensity of the diffusely scattered light from a rough surface...

  6. Enhanced photochemistry on metal surfaces

    International Nuclear Information System (INIS)

    Goncher, G.M.; Parsons, C.A.; Harris, C.B.

    1984-01-01

    Due to the fast relaxation of molecular excited states in the vicinity of a metal or semiconductor surface, few observations of surface photochemistry have been reported. The following work concerns the surface-enhanced photo-reactions of a variety of physisorbed molecules on roughened Ag surfaces. In summary, photodecomposition leads to a graphitic surface carbon product which is monitored via surface-enhanced Raman scattering. In most cases an initial two-photon molecular absorption step followed by further absorption and fragmentation is thought to occur. Enhancement of the incident fields occurs through roughness-mediated surface plasmon resonances. This mechanism provides the amplified electromagnetic surface fields responsible for the observed photodecomposition. The photodecomposition experiments are performed under ultra-high vacuum. Surface characterization of the roughened surfaces was done by Scanning Electron Microscopy (SEM), and electron-stimulated emission. The SEM revealed morphology on the order of 300-400 A. This size of roughness feature, when modelled as isolated spheres should exhibit the well-known Mie resonances for light of the correct wavelengths. For protrusions existing on a surface these Mie resonances can be thought of as a coupling of the light with the surface plasmon. Experimental verification of these resonances was provided by the electron-stimulated light emission results. These showed that a polished Ag surface emitted only the expected transition radiation at the frequency of the Ag bulk plasmon. Upon roughening, however, a broad range of lower frequencies extending well into the visible are seen from electron irradiation of the surface. Large enhancements are expected for those frequencies which are able to couple into the surface modes

  7. Surface-Enhanced Raman Spectroscopy

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 15; Issue 2. Surface-Enhanced Raman Spectroscopy - Recent Advancement of Raman Spectroscopy. Ujjal Kumar Sur. General Article Volume 15 Issue 2 February 2010 pp 154-164 ...

  8. Probing turbid medium structure using ultra low coherence enhanced backscattering spectroscopy

    Science.gov (United States)

    DeAngelo, Bianca; Arzumanov, Grant; Matovu, Charles; Shanley, Patrick; Zeylikovich, Joseph; Xu, M.

    2010-02-01

    We report on experimental results and theoretical investigation on probing the structure of turbid medium using ultra low coherence enhanced backscattering spectroscopy where the spatial coherence length of the incident line light is not greater than 25 μm. The periodic structure contained in the low coherence enhanced backscattering spectroscopy is found to decrease with the dominant scatterer size. A theoretical model is proposed to explain the observations and is verified by Monte Carlo simulations.

  9. 3D Human cartilage surface characterization by optical coherence tomography

    Science.gov (United States)

    Brill, Nicolai; Riedel, Jörn; Schmitt, Robert; Tingart, Markus; Truhn, Daniel; Pufe, Thomas; Jahr, Holger; Nebelung, Sven

    2015-10-01

    Early diagnosis and treatment of cartilage degeneration is of high clinical interest. Loss of surface integrity is considered one of the earliest and most reliable signs of degeneration, but cannot currently be evaluated objectively. Optical Coherence Tomography (OCT) is an arthroscopically available light-based non-destructive real-time imaging technology that allows imaging at micrometre resolutions to millimetre depths. As OCT-based surface evaluation standards remain to be defined, the present study investigated the diagnostic potential of 3D surface profile parameters in the comprehensive evaluation of cartilage degeneration. To this end, 45 cartilage samples of different degenerative grades were obtained from total knee replacements (2 males, 10 females; mean age 63.8 years), cut to standard size and imaged using a spectral-domain OCT device (Thorlabs, Germany). 3D OCT datasets of 8  ×  8, 4  ×  4 and 1  ×  1 mm (width  ×  length) were obtained and pre-processed (image adjustments, morphological filtering). Subsequent automated surface identification algorithms were used to obtain the 3D primary profiles, which were then filtered and processed using established algorithms employing ISO standards. The 3D surface profile thus obtained was used to calculate a set of 21 3D surface profile parameters, i.e. height (e.g. Sa), functional (e.g. Sk), hybrid (e.g. Sdq) and segmentation-related parameters (e.g. Spd). Samples underwent reference histological assessment according to the Degenerative Joint Disease classification. Statistical analyses included calculation of Spearman’s rho and assessment of inter-group differences using the Kruskal Wallis test. Overall, the majority of 3D surface profile parameters revealed significant degeneration-dependent differences and correlations with the exception of severe end-stage degeneration and were of distinct diagnostic value in the assessment of surface integrity. None of the 3D

  10. Optical coherence tomography of the epidermal sulfakrilate surface strippings

    Directory of Open Access Journals (Sweden)

    Utz S.R.

    2013-09-01

    Full Text Available Method of the epidermal surface biopsy (ESB with the adhesive compositions is the alter-native to the classic his-tological examination. Materials and Methods. In this study medical adhesive "Sulfacrylate" was used, small portions of which had been spread on an object glass, and then on different skin areas. To study the structural organization of the samples ESB the technique of optical coherence tomography (ОСТ was used. Results. We obtained the pictures that visualize the structural organization of the different layers of the epidermis in lichen planus, hyperkeratosis, scabies and other skin diseases. Conclusion. This technique allows non-invasive measurement of high-precision structure of different layers of the epidermis, which can be useful both for research and for the practical dermatology.

  11. Coherence-enhanced efficiency of feedback-driven quantum engines

    Science.gov (United States)

    Brandner, Kay; Bauer, Michael; Schmid, Michael T.; Seifert, Udo

    2015-06-01

    A genuine feature of projective quantum measurements is that they inevitably alter the mean energy of the observed system if the measured quantity does not commute with the Hamiltonian. Compared to the classical case, Jacobs proved that this additional energetic cost leads to a stronger bound on the work extractable after a single measurement from a system initially in thermal equilibrium (2009 Phys. Rev. A 80 012322). Here, we extend this bound to a large class of feedback-driven quantum engines operating periodically and in finite time. The bound thus implies a natural definition for the efficiency of information to work conversion in such devices. For a simple model consisting of a laser-driven two-level system, we maximize the efficiency with respect to the observable whose measurement is used to control the feedback operations. We find that the optimal observable typically does not commute with the Hamiltonian and hence would not be available in a classical two level system. This result reveals that periodic feedback engines operating in the quantum realm can exploit quantum coherences to enhance efficiency.

  12. Two-Photon Infrared Resonance Can Enhance Coherent Raman Scattering

    Science.gov (United States)

    Traverso, Andrew J.; Hokr, Brett; Yi, Zhenhuan; Yuan, Luqi; Yamaguchi, Shoichi; Scully, Marlan O.; Yakovlev, Vladislav V.

    2018-02-01

    In this Letter we present a new technique for attaining efficient low-background coherent Raman scattering where the Raman coherence is mediated by a tunable infrared laser in two-photon resonance with a chosen vibrational transition. In addition to the traditional benefits of conventional coherent Raman schemes, this approach offers a number of advantages including potentially higher emission intensity, reduction of nonresonant four-wave mixing background, preferential excitation of the anti-Stokes field, and simplified phase matching conditions. In particular, this is demonstrated in gaseous methane along the ν1 (A1) and ν3 (T2) vibrational levels using an infrared field tuned between 1400 and 1600 cm-1 and a 532-nm pump field. This approach has broad applications, from coherent light generation to spectroscopic remote sensing and chemically specific imaging in microscopy.

  13. Dynamic random links enhance diversity-induced coherence in ...

    Indian Academy of Sciences (India)

    Abstract. We investigate the influence of diversity on the temporal regularity of spiking in a ring of coupled model neurons. We find diversity-induced coherence in the spike events, with an optimal amount of parametric heterogeneity at the nodal level yielding the greatest regularity in the spike train. Further, we investigate ...

  14. Review of spectral domain enhanced depth imaging optical coherence tomography of tumors of the choroid

    Directory of Open Access Journals (Sweden)

    Carol L Shields

    2015-01-01

    Full Text Available Background: Spectral domain enhanced depth imaging optical coherence tomography (EDI-OCT can provide anatomic localization of intraocular tumors. Aims: The aim was to identify topographical and intrinsic patterns of choroidal tumors on EDI-OCT. Settings and Design: Retrospective review. Materials and Methods: Analysis of published reports and personal observations using office based EDI-OCT. Results: Using EDI-OCT, choroidal nevus displayed a smooth, dome-shaped topography with overlying retinal pigment epithelium alterations, drusen, and occasional subretinal cleft demonstrating photoreceptor loss. Small choroidal melanoma showed smooth, moderately dome-shaped topography, commonly with overlying shallow subretinal fluid that often depicted "shaggy" photoreceptors. Choroidal metastasis showed a minimally "lumpy, bumpy" surface topography and with overlying subretinal fluid and shaggy photoreceptors. Choroidal hemangioma showed a smooth, dome-shaped topography, with expansion of the affected small, medium, and large choroidal vessels. Choroidal lymphoma showed varying topography with increasing tumor thickness as "flat, rippled, or undulating (seasick" surface. Choroidal osteoma displayed a smooth undulating surface with visible intralesional horizontal lines suggestive of bone lamellae and occasional horizontal and vertical tubules with intralesional "spongy" flecks. Choroidal melanocytosis appeared as uniformly thickened choroid with increased stromal density surrounding the normal choroidal vascular structures. Conclusions: Enhanced depth imaging-OCT can depict characteristic patterns that are suggestive of various choroidal tumors.

  15. An Enhanced Non-Coherent Pre-Filter Design for Tracking Error Estimation in GNSS Receivers.

    Science.gov (United States)

    Luo, Zhibin; Ding, Jicheng; Zhao, Lin; Wu, Mouyan

    2017-11-18

    Tracking error estimation is of great importance in global navigation satellite system (GNSS) receivers. Any inaccurate estimation for tracking error will decrease the signal tracking ability of signal tracking loops and the accuracies of position fixing, velocity determination, and timing. Tracking error estimation can be done by traditional discriminator, or Kalman filter-based pre-filter. The pre-filter can be divided into two categories: coherent and non-coherent. This paper focuses on the performance improvements of non-coherent pre-filter. Firstly, the signal characteristics of coherent and non-coherent integration-which are the basis of tracking error estimation-are analyzed in detail. After that, the probability distribution of estimation noise of four-quadrant arctangent (ATAN2) discriminator is derived according to the mathematical model of coherent integration. Secondly, the statistical property of observation noise of non-coherent pre-filter is studied through Monte Carlo simulation to set the observation noise variance matrix correctly. Thirdly, a simple fault detection and exclusion (FDE) structure is introduced to the non-coherent pre-filter design, and thus its effective working range for carrier phase error estimation extends from (-0.25 cycle, 0.25 cycle) to (-0.5 cycle, 0.5 cycle). Finally, the estimation accuracies of discriminator, coherent pre-filter, and the enhanced non-coherent pre-filter are evaluated comprehensively through the carefully designed experiment scenario. The pre-filter outperforms traditional discriminator in estimation accuracy. In a highly dynamic scenario, the enhanced non-coherent pre-filter provides accuracy improvements of 41.6%, 46.4%, and 50.36% for carrier phase error, carrier frequency error, and code phase error estimation, respectively, when compared with coherent pre-filter. The enhanced non-coherent pre-filter outperforms the coherent pre-filter in code phase error estimation when carrier-to-noise density ratio

  16. Study on internal to surface fingerprint correlation using optical coherence tomography and internal fingerprint extraction

    CSIR Research Space (South Africa)

    Darlow, LN

    2015-11-01

    Full Text Available Surface fingerprint scanners are limited to a two-dimensional representation of the fingerprint topography, and thus, are vulnerable to fingerprint damage, distortion, and counterfeiting. Optical coherence tomography (OCT) scanners are able to image...

  17. Complementary surface charge for enhanced capacitive deionization

    NARCIS (Netherlands)

    Gao, X.; Porada, S.; Omosebi, A.; Liu, K.L.; Biesheuvel, P.M.; Landon, J.

    2016-01-01

    Commercially available activated carbon cloth electrodes are treated using nitric acid and ethylenediamine solutions, resulting in chemical surface charge enhanced carbon electrodes for capacitive deionization (CDI) applications. Surface charge enhanced electrodes are then configured in a CDI

  18. Surface-enhanced FAST CARS: en route to quantum nano-biophotonics

    Science.gov (United States)

    Voronine, Dmitri V.; Zhang, Zhenrong; Sokolov, Alexei V.; Scully, Marlan O.

    2018-02-01

    Quantum nano-biophotonics as the science of nanoscale light-matter interactions in biological systems requires developing new spectroscopic tools for addressing the challenges of detecting and disentangling weak congested optical signals. Nanoscale bio-imaging addresses the challenge of the detection of weak resonant signals from a few target biomolecules in the presence of the nonresonant background from many undesired molecules. In addition, the imaging must be performed rapidly to capture the dynamics of biological processes in living cells and tissues. Label-free non-invasive spectroscopic techniques are required to minimize the external perturbation effects on biological systems. Various approaches were developed to satisfy these requirements by increasing the selectivity and sensitivity of biomolecular detection. Coherent anti-Stokes Raman scattering (CARS) and surface-enhanced Raman scattering (SERS) spectroscopies provide many orders of magnitude enhancement of chemically specific Raman signals. Femtosecond adaptive spectroscopic techniques for CARS (FAST CARS) were developed to suppress the nonresonant background and optimize the efficiency of the coherent optical signals. This perspective focuses on the application of these techniques to nanoscale bio-imaging, discussing their advantages and limitations as well as the promising opportunities and challenges of the combined coherence and surface enhancements in surface-enhanced coherent anti-Stokes Raman scattering (SECARS) and tip-enhanced coherent anti-Stokes Raman scattering (TECARS) and the corresponding surface-enhanced FAST CARS techniques. Laser pulse shaping of near-field excitations plays an important role in achieving these goals and increasing the signal enhancement.

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

    Indian Academy of Sciences (India)

    Administrator

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

  20. COFFEE - Coherent Optical System Field Trial for Spectral Efficiency Enhancement

    DEFF Research Database (Denmark)

    Imran, Muhammad; Fresi, Francesco; Rommel, Simon

    2016-01-01

    The scope, aims, and contributions of the COFFEE project for spectral efficiency enhancement and market exposure are presented.......The scope, aims, and contributions of the COFFEE project for spectral efficiency enhancement and market exposure are presented....

  1. On the spectra and coherence of some surface meteorological parameters in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    RameshKumar, M.R.; Fernandes, A.A.

    . In addition to peaks in the annual, semiannual and four-month periodicities, the various surface parameters exhibited some energy at 2, 3 and 4 year cycles. It was also found that most of the surface meteorological parameters were coherent (at 95% confidence...

  2. Enhanced linear-array photoacoustic beamforming using modified coherence factor.

    Science.gov (United States)

    Mozaffarzadeh, Moein; Yan, Yan; Mehrmohammadi, Mohammad; Makkiabadi, Bahador

    2018-02-01

    Photoacoustic imaging (PAI) is a promising medical imaging modality providing the spatial resolution of ultrasound imaging and the contrast of optical imaging. For linear-array PAI, a beamformer can be used as the reconstruction algorithm. Delay-and-sum (DAS) is the most prevalent beamforming algorithm in PAI. However, using DAS beamformer leads to low-resolution images as well as high sidelobes due to nondesired contribution of off-axis signals. Coherence factor (CF) is a weighting method in which each pixel of the reconstructed image is weighted, based on the spatial spectrum of the aperture, to mainly improve the contrast. We demonstrate that the numerator of the formula of CF contains a DAS algebra and propose the use of a delay-multiply-and-sum beamformer instead of the available DAS on the numerator. The proposed weighting technique, modified CF (MCF), has been evaluated numerically and experimentally compared to CF. It was shown that MCF leads to lower sidelobes and better detectable targets. The quantitative results of the experiment (using wire targets) show that MCF leads to for about 45% and 40% improvement, in comparison with CF, in the terms of signal-to-noise ratio and full-width-half-maximum, respectively. (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

  3. Enhanced linear-array photoacoustic beamforming using modified coherence factor

    Science.gov (United States)

    Mozaffarzadeh, Moein; Yan, Yan; Mehrmohammadi, Mohammad; Makkiabadi, Bahador

    2018-02-01

    Photoacoustic imaging (PAI) is a promising medical imaging modality providing the spatial resolution of ultrasound imaging and the contrast of optical imaging. For linear-array PAI, a beamformer can be used as the reconstruction algorithm. Delay-and-sum (DAS) is the most prevalent beamforming algorithm in PAI. However, using DAS beamformer leads to low-resolution images as well as high sidelobes due to nondesired contribution of off-axis signals. Coherence factor (CF) is a weighting method in which each pixel of the reconstructed image is weighted, based on the spatial spectrum of the aperture, to mainly improve the contrast. We demonstrate that the numerator of the formula of CF contains a DAS algebra and propose the use of a delay-multiply-and-sum beamformer instead of the available DAS on the numerator. The proposed weighting technique, modified CF (MCF), has been evaluated numerically and experimentally compared to CF. It was shown that MCF leads to lower sidelobes and better detectable targets. The quantitative results of the experiment (using wire targets) show that MCF leads to for about 45% and 40% improvement, in comparison with CF, in the terms of signal-to-noise ratio and full-width-half-maximum, respectively.

  4. Pseudo-Coherence-Based MVDR Beamformer for Speech Enhancement with Ad Hoc Microphone Arrays

    DEFF Research Database (Denmark)

    Tavakoli, Vincent Mohammad; Jensen, Jesper Rindom; Christensen, Mads Græsbøll

    2015-01-01

    . This paper proposes minimum variance distortionless response filtering based on multichannel pseudo-coherence for speech enhancement with ad hoc microphone arrays. This method requires neither position information nor control of the trade-off used in the distortion weighted methods. Furthermore, certain...... performance criteria are derived in terms of the pseudo-coherence vector, and the method is compared with the multichannel Wiener filter. Evaluation shows the suitability of the proposed method in terms of noise reduction with minimum distortion in ad hoc scenarios....

  5. Optical coherence tomography-enhanced microlaryngoscopy: preliminary report of a noncontact optical coherence tomography system integrated with a surgical microscope.

    Science.gov (United States)

    Vokes, David E; Jackson, Ryan; Guo, Shuguang; Perez, Jorge A; Su, Jianping; Ridgway, James M; Armstrong, William B; Chen, Zhongping; Wong, Brian J F

    2008-07-01

    Optical coherence tomography (OCT) is a new imaging modality that uses near-infrared light to produce cross-sectional images of tissue with a resolution approaching that of light microscopy. We have previously reported use of OCT imaging of the vocal folds (VFs) during direct laryngoscopy with a probe held in contact or near-contact with the VFs. This aim of this study was to develop and evaluate a novel OCT system integrated with a surgical microscope to allow hands-free OCT imaging of the VFs, which could be performed simultaneously with microscopic visualization. We performed a prospective evaluation of a new method of acquiring OCT images of the VFs. An OCT system was successfully integrated with a surgical microscope to permit noncontact OCT imaging of the VFs of 10 patients. With this novel device we were able to identify VF epithelium and lamina propria; however, the resolution was reduced compared to that achieved with the standard contact or near-contact OCT. Optical coherence tomography is able to produce high-resolution images of vocal fold mucosa to a maximum depth of 1.6 mm. It may be used in the diagnosis of VF lesions, particularly early squamous cell carcinoma, in which OCT can show disruption of the basement membrane. Mounting the OCT device directly onto the operating microscope allows hands-free noncontact OCT imaging and simultaneous conventional microscopic visualization of the VFs. However, the lateral resolution of the OCT microscope system is 50 microm, in contrast to the conventional handheld probe system (10 microm). Although such images at this resolution are still useful clinically, improved resolution would enhance the system's performance, potentially enabling real-time OCT-guided microsurgery of the larynx.

  6. Surface-enhanced Raman spectroscopy of double-shell hollow nanoparticles: electromagnetic and chemical enhancements.

    Science.gov (United States)

    Mahmoud, Mahmoud A

    2013-05-28

    Enhancements of the Raman signal by the newly prepared gold-palladium and gold-platinum double-shell hollow nanoparticles were examined and compared with those using gold nanocages (AuNCs). The surface-enhanced Raman spectra (SERS) of thiophenol adsorbed on the surface of AuNCs assembled into a Langmuir-Blodgett monolayer were 10-fold stronger than AuNCs with an inner Pt or Pd shell. The chemical and electromagnetic enhancement mechanisms for these hollow nanoparticles were further proved by comparing the Raman enhancement of nitrothiophenol and nitrotoulene. Nitrothiophenol binds to the surface of the nanoparticles by covalent interaction, and Raman enhancement by both the two mechanisms is possible, while nitrotoulene does not form any chemical bond with the surface of the nanoparticles and hence no chemical enhancement is expected. Based on discrete dipole approximation (DDA) calculations and the experimental SERS results, AuNCs introduced a high electromagnetic enhancement, while the nanocages with inner Pt or Pd shell have a strong chemical enhancement. The optical measurements of the localized surface plasmon resonance (LSPR) of the nanocages with an outer Au shell and an inner Pt or Pd shell were found, experimentally and theoretically, to be broad compared with AuNCs. The possible reason could be due to the decrease of the coherence time of Au oscillated free electrons and fast damping of the plasmon energy. This agreed well with the fact that a Pt or Pd inner nanoshell decreases the electromagnetic field of the outer Au nanoshell while increasing the SERS chemical enhancement.

  7. Surface-Enhanced Raman Spectroscopy

    Indian Academy of Sciences (India)

    IAS Admin

    In Raman spectroscopy, inelastic scattering of photons from an atom or molecule in chemical entities is utilized to analyze the composition of solids, liquids and gases. However, the low cross-section limits its applications. The introduction of sur- face-enhanced Raman spectroscopy in 1974 has attracted a lot of attention ...

  8. Enhancing cavitation with micromachined surfaces

    Science.gov (United States)

    Fernandez Rivas, David; Stricker, Laura; Zijlstra, Aaldert G.; Gardeniers, Han; Lohse, Detlef; Prosperetti, Andrea; Mesoscale Chemical System Group Collaboration; Physics of Fluids Group Collaboration; Department of Mechanical Engineering Collaboration

    2012-11-01

    When a silicon surface with micromachined pits submerged in a liquid is exposed to continuous ultrasound at 200 kHz, bubbles are ejected from the air filled cavities. Depending on the pressure amplitude different scenarios are observed, as the bubbles ejected from the micropits interact in complex ways with each other, and with the silicon surface. We have determined the size distribution of bubbles ejected from one, two and three pits for three different electrical power settings, and correlated them with sonochemical OH* radical production. Numerical simulations of the sonochemical conversion reaction rates were obtained using the empirical bubble size distributions and are compared with experimental results. Experimental evidence of shock wave emission from the microbubble clusters, deformed microbubble shapes, jetting and surface erosion are also presented. Financially supported through the project 07391 of the Technology Foundation STW, The Netherlands.

  9. Coherent and Tunable Terahertz Radiation from Graphene Surface Plasmon Polarirons Excited by Cyclotron Electron Beam

    Science.gov (United States)

    Zhao, Tao; Gong, Sen; Hu, Min; Zhong, Renbin; Liu, Diwei; Chen, Xiaoxing; Zhang, Ping; Wang, Xinran; Zhang, Chao; Wu, Peiheng; Liu, Shenggang

    2015-01-01

    Terahertz (THz) radiation can revolutionize modern science and technology. To this date, it remains big challenges to develop intense, coherent and tunable THz radiation sources that can cover the whole THz frequency region either by means of only electronics (both vacuum electronics and semiconductor electronics) or of only photonics (lasers, for example, quantum cascade laser). Here we present a mechanism which can overcome these difficulties in THz radiation generation. Due to the natural periodicity of 2π of both the circular cylindrical graphene structure and cyclotron electron beam (CEB), the surface plasmon polaritions (SPPs) dispersion can cross the light line of dielectric, making transformation of SPPs into radiation immediately possible. The dual natural periodicity also brings significant excellences to the excitation and the transformation. The fundamental and hybrid SPPs modes can be excited and transformed into radiation. The excited SPPs propagate along the cyclotron trajectory together with the beam and gain energy from the beam continuously. The radiation density is enhanced over 300 times, up to 105 W/cm2. The radiation frequency can be widely tuned by adjusting the beam energy or chemical potential. This mechanism opens a way for developing desired THz radiation sources to cover the whole THz frequency regime. PMID:26525516

  10. The Impact of Very High Frequency Surface Reverberation on Coherent Acoustic Propagation and Modeling

    Science.gov (United States)

    2015-09-30

    on Coherent Acoustic Propagation and Modeling Grant B. Deane Marine Physical Laboratory , Scripps Institution of Oceanography UCSD La Jolla, CA...long-term science objective is to develop a physical model of high-frequency scattering of underwater acoustic signals from the sea surface under a... acoustic communications problem. The scattering of sound from the sea surface is important for the operation of underwater sonar and underwater

  11. Coherence and polarization speckle generated by a rough-surfaced retardation plate depolarizer

    DEFF Research Database (Denmark)

    Ma, Ning; Hanson, Steen Grüner; Takeda, Mitsuo

    2015-01-01

    of position introducing random phase differences between the two orthogonal components of the electric vector. Under the assumption of Gaussian statistics with zero mean, the surface model for the depolarizer of the rough-surfaced retardation plate is obtained. The propagation of the modulated fields through...... any quadratic optical system is examined within the framework of the complex ABCD matrix theory to show how the degree of coherence and polarization of the beam changes on propagation, including propagation in free space...

  12. Microscale surface modifications for heat transfer enhancement.

    Science.gov (United States)

    Bostanci, Huseyin; Singh, Virendra; Kizito, John P; Rini, Daniel P; Seal, Sudipta; Chow, Louis C

    2013-10-09

    In this experimental study, two surface modification techniques were investigated for their effect on heat transfer enhancement. One of the methods employed the particle (grit) blasting to create microscale indentations, while the other used plasma spray coating to create microscale protrusions on Al 6061 (aluminum alloy 6061) samples. The test surfaces were characterized using scanning electron microscopy (SEM) and confocal scanning laser microscopy. Because of the surface modifications, the actual surface area was increased up to 2.8× compared to the projected base area, and the arithmetic mean roughness value (Ra) was determined to vary from 0.3 μm for the reference smooth surface to 19.5 μm for the modified surfaces. Selected samples with modified surfaces along with the reference smooth surface were then evaluated for their heat transfer performance in spray cooling tests. The cooling system had vapor-atomizing nozzles and used anhydrous ammonia as the coolant in order to achieve heat fluxes up to 500 W/cm(2) representing a thermal management setting for high power systems. Experimental results showed that the microscale surface modifications enhanced heat transfer coefficients up to 76% at 500 W/cm(2) compared to the smooth surface and demonstrated the benefits of these practical surface modification techniques to enhance two-phase heat transfer process.

  13. Surface-enhanced Raman spectroscopy: nonlocal limitations

    DEFF Research Database (Denmark)

    Toscano, Giuseppe; Raza, S.; Xiao, Sanshui

    2012-01-01

    for our understanding of surface-enhanced Raman spectroscopy (SERS). The intrinsic length scale of the electron gas serves to smear out assumed field singularities, leaving the SERS enhancement factor finite, even for geometries with infinitely sharp features. For silver nanogroove structures, mimicked...... by periodic arrays of half-cylinders (up to 120 nm in radius), we find no enhancement factors exceeding 10 orders of magnitude (10(10)). (C) 2012 Optical Society of America...

  14. Surface-enhanced Raman spectroscopy: nonlocal limitations

    DEFF Research Database (Denmark)

    Toscano, Giuseppe; Raza, Søren; Xiao, Sanshui

    2012-01-01

    for our understanding of surface-enhanced Raman spectroscopy (SERS). The intrinsic length scale of the electron gas serves to smear out assumed field singularities, leaving the SERS enhancement factor finite, even for geometries with infinitely sharp features. For silver nanogroove structures, mimicked...... by periodic arrays of half-cylinders (up to 120 nm in radius), we find no enhancement factors exceeding 10 orders of magnitude (1010)....

  15. Impact of Surface Functionalization on the Quantum Coherence of Nitrogen-Vacancy Centers in Nanodiamonds.

    Science.gov (United States)

    Ryan, Robert G; Stacey, Alastair; O'Donnell, Kane M; Ohshima, Takeshi; Johnson, Brett C; Hollenberg, Lloyd C L; Mulvaney, Paul; Simpson, David A

    2018-04-18

    Nanoscale quantum probes such as the nitrogen-vacancy (NV) center in diamonds have demonstrated remarkable sensing capabilities over the past decade as control over fabrication and manipulation of these systems has evolved. The biocompatibility and rich surface chemistry of diamonds has added to the utility of these probes but, as the size of these nanoscale systems is reduced, the surface chemistry of diamond begins to impact the quantum properties of the NV center. In this work, we systematically study the effect of the diamond surface chemistry on the quantum coherence of the NV center in nanodiamonds (NDs) 50 nm in size. Our results show that a borane-reduced diamond surface can on average double the spin relaxation time of individual NV centers in nanodiamonds when compared to thermally oxidized surfaces. Using a combination of infrared and X-ray absorption spectroscopy techniques, we correlate the changes in quantum relaxation rates with the conversion of sp 2 carbon to C-O and C-H bonds on the diamond surface. These findings implicate double-bonded carbon species as a dominant source of spin noise for near surface NV centers. The link between the surface chemistry and quantum coherence indicates that through tailored engineering of the surface, the quantum properties and magnetic sensitivity of these nanoscale systems may approach that observed in bulk diamond.

  16. Electron emission induced by resonant coherent ion-surface interaction at grazing incidence

    International Nuclear Information System (INIS)

    Garcia de Abajo, F.J.; Ponce, V.H.; Echenique, P.M.

    1992-01-01

    A new spectroscopy based on the resonant coherently induced electron loss to the continuum in ion-surface scattering under grazing incidence is proposed. A series of peaks, corresponding to the energy differences determined by the resonant interaction with the rows of atoms in the surface, is predicted to appear in the energy distribution of electrons emitted from electronic states bound to the probe. Calculations for MeV He + ions scattered at a W(001) surface along the left-angle 100 right-angle direction with a glancing angle of 0--2 mrad show a total yield close to 1

  17. Enhanced depth imaging optical coherence tomography of deep optic nerve complex structures in glaucoma.

    Science.gov (United States)

    Park, Sung Chul; De Moraes, Carlos Gustavo V; Teng, Christopher C; Tello, Celso; Liebmann, Jeffrey M; Ritch, Robert

    2012-01-01

    To assess the usefulness of enhanced depth imaging (EDI) optical coherence tomography (OCT) for evaluating deep structures of the optic nerve complex (ONC; optic nerve head and peripapillary structures) in glaucoma. Prospective, observational study. Seventy-three established glaucoma patients (139 eyes) with a range of glaucomatous damage. Serial horizontal and vertical EDI OCT images of the ONC were obtained from both eyes of each participant. Deep ONC structures, including the lamina cribrosa (LC), short posterior ciliary artery (SPCA), central retinal artery (CRA), central retinal vein (CRV), peripapillary choroid and sclera, and subarachnoid space around the optic nerve, were investigated for their visibility and morphologic features. Deep ONC structures identified in EDI OCT images. Visual field mean deviation of 139 included eyes was -11.8 ± 8.6 dB (range, -28.70 to -2.01 dB). The anterior laminar surface was identified in all eyes in the central laminar area and in 91 (65%) eyes in the periphery beneath the neuroretinal and scleral rims or vascular structures. The LC pores with various shapes and sizes were visualized in 106 (76%) eyes, mainly in the central and temporal areas of the LC. Localized LC lesions seen on optic disc photographs were identified as focal LC defects (partial loss of LC tissue) in the EDI OCT images. The locations of the CRA and CRV were identified in all eyes. In the LC, the CRA maintained a straight shape with a consistent caliber, but the CRV (and tributaries) assumed a more irregular shape. The SPCAs, their branches through the emissary canals in the sclera, or both were visualized in 120 (86%) eyes. The subarachnoid space around the optic nerve was identified with varying degrees of clarity in 25 eyes (18%): 17 had high myopia and extensive parapapillary atrophy. Intrachoroidal cavitation or choroidal schisis, which had been unrecognized clinically, was identified in 2 eyes (1%) with high myopia. Enhanced depth imaging OCT was

  18. Investigation of acid-etched CO2 laser ablated enamel surfaces using polarization sensitive optical coherence tomography

    Science.gov (United States)

    Nahm, Byung J.; Kang, Hobin; Chan, Kenneth; Fried, Daniel

    2012-01-01

    A carbon dioxide laser operating at the highly absorbed wavelength of 9.3μm with a pulse duration of 10-15μs is ideally suited for caries removal and caries prevention. The enamel thermally modified by the laser has enhanced resistance to acid dissolution. This is an obvious advantage for caries prevention; however, it is often necessary to etch the enamel surface to increase adhesion to composite restorative materials and such surfaces may be more resistant to etching. The purpose of the study was to non-destructively measure the susceptibility of laser-ablated enamel surfaces to acid dissolution before and after acid-etching using Polarization Sensitive Optical Coherence Tomography (PS-OCT). PS-OCT was used to acquire images of bovine enamel surfaces after exposure to laser irradiation at ablative fluence, acid-etching, and a surface softened dissolution model. The integrated reflectivity from lesion and the lesion depth were measured using PS-OCT. Samples were also sectioned for examination by Polarized Light Microscopy (PLM). PS-OCT images showed that acid-etching greatly accelerated the formation of subsurface lesions on both laser-irradiated and non-irradiated surfaces (Plaser modified enamel layer after 5-10 seconds.

  19. Resonant coherent ionization in grazing ion/atom-surface collisions at high velocities

    International Nuclear Information System (INIS)

    Garcia de Abajo, F.J.; Pitarke, J.M.

    1994-01-01

    The resonant coherent interaction of a fast ion/atom with an oriented crystal surface under grazing incidence conditions is shown to contribute significantly to ionize the probe for high enough velocities and motion along a random direction. The dependence of this process on both the distance to the surface and the velocity of the projectile is studied in detail. We focus on the case of hydrogen moving with a velocity above 2 a.u. Comparison with other mechanisms of charge transfer, such as capture from inner shells of the target atoms, permits us to draw some conclusions about the charge state of the outgoing projectiles. (orig.)

  20. Surface enhanced raman spectroscopy on chip

    DEFF Research Database (Denmark)

    Hübner, Jörg; Anhøj, Thomas Aarøe; Zauner, Dan

    2007-01-01

    In this paper we report low resolution surface enhanced Raman spectra (SERS) conducted with a chip based spectrometer. The flat field spectrometer presented here is fabricated in SU-8 on silicon, showing a resolution of around 3 nm and a free spectral range of around 100 nm. The output facet...... fiber. The obtained spectra show that chip based spectrometer together with the SERS active surface can be used as Raman sensor....

  1. Canard explosion and coherent biresonance in the rate oscillation of CO oxidation on platinum surface.

    Science.gov (United States)

    Zhao, Gang; Hou, Zhonghuai; Xin, Houwen

    2005-09-29

    The relationship between canard explosion and coherent biresonance is analyzed by numerically investigating a temporal dynamical model of CO oxidation on Pt surface. Canard explosion, manifesting itself by a dramatic change in the amplitude and period of a periodic orbit within a very narrow interval of a control parameter, is the result of multiple time scales in a dynamical system and is common in excitable systems. Coherent biresonance, namely, two peaks on the signal-to-noise ratio (SNR) curve when varying noise intensity, is a novel phenomenon of coherent resonance which is well-known in excitable systems. When the control parameter is varied from a stable fixed point, crossing the supercritical Hopf bifurcation, one of the peaks that corresponds to relatively larger noise intensity, keeps a constant height and position, while the other becomes higher and moves to lower noise level. When we consider the case in which two control parameters are perturbed by independent noise simultaneously, an interesting picture of one valley between two ridges appears on the 3D surface of SNR.

  2. Feshbach-Resonance-Enhanced Coherent Atom-Molecule Conversion with Ultranarrow Photoassociation Resonance

    Science.gov (United States)

    Taie, Shintaro; Watanabe, Shunsuke; Ichinose, Tomohiro; Takahashi, Yoshiro

    2016-01-01

    We reveal the existence of high-density Feshbach resonances in the collision between the ground and metastable states of 171Yb and coherently produce the associated Feshbach molecules by photoassociation. The extremely small transition rate is overcome by the enhanced Franck-Condon factor of the weakly bound Feshbach molecule, allowing us to observe Rabi oscillations with long decay time between an atom pair and a molecule in an optical lattice. We also perform the precision measurement of the binding energies, which characterizes the observed resonances. The ultranarrow photoassociation will be a basis for practical implementation of optical Feshbach resonances.

  3. A novel technique of contrast-enhanced optical coherence tomography imaging in evaluation of clearance of lipids in human tears.

    Science.gov (United States)

    Napoli, Pietro Emanuele; Coronella, Franco; Satta, Giovanni Maria; Fossarello, Maurizio

    2014-01-01

    The aim of this work was to gather preliminary data in different conditions of healthy eyes, aqueous tear deficient dry eyes, obstructive meibomian gland disease (MGD) and non-obvious obstructive MGD (NOMGD) individuals, using a new, contrast-enhanced optical coherence tomography (OCT) imaging method to evaluate the clearance of lipids in human tears. Eighty-two adult patients presenting with complaints of ocular irritation were studied for abnormalities of the ocular surface and classified as healthy (n = 21), aqueous tear deficient dry eyes (n = 20), obstructive MGD (n = 15) and NOMGD (n = 26) individuals. A lipid-based tracer, containing an oil-in-water emulsion, was used to obtain an enhanced OCT imaging of the lower tear meniscus. After instillation, a dramatic initial increase of reflectivity of the lower tear meniscus was detected by OCT, followed by a decay back to baseline values over time. Based on this finding, the clearance of lipids was measured in real-time by Fourier-domain anterior segment OCT. The differences in the clearance of lipids among the four groups as well as the correlations between symptom questionnaire score, standardized visual scale test, fluorescein break-up time, ocular surface fluorescein staining score, Schirmer I test scores were found to be statistically significant. The individual areas under the curve of the clearance of lipids calculated by the receiver operating characteristic curve technique ranged from 0.66 to 0.98, suggesting reliable sensitivity and specificity of lipid-enhanced OCT imaging. This new technique of contrast-enhanced OCT imaging of the tear film following lipid-based tracer instillation provides a measure of the clearance of lipids. The quantitative values found are in agreement with other methods of evaluation of the lacrimal system. An improvement of the clinician's ability in the diagnosis and understanding of abnormalities of the ocular surface may be achieved by this simple approach.

  4. Coherent changes of wintertime surface air temperatures over North Asia and North America.

    Science.gov (United States)

    Yu, Bin; Lin, Hai

    2018-03-29

    The surface temperature variance and its potential change with global warming are most prominent in winter over Northern Hemisphere mid-high latitudes. Consistent wintertime surface temperature variability has been observed over large areas in Eurasia and North America on a broad range of time scales. However, it remains a challenge to quantify where and how the coherent change of temperature anomalies occur over the two continents. Here we demonstrate the coherent change of wintertime surface temperature anomalies over North Asia and the central-eastern parts of North America for the period from 1951 to 2015. This is supported by the results from the empirical orthogonal function analysis of surface temperature and temperature trend anomalies over the Northern Hemisphere extratropical lands and the timeseries analysis of the regional averaged temperature anomalies over North Asia and the Great Plains and Great Lakes. The Asian-Bering-North American (ABNA) teleconnection provides a pathway to connect the regional temperature anomalies over the two continents. The ABNA is also responsible for the decadal variation of the temperature relationship between North Asia and North America.

  5. Enhancing early bladder cancer detection with fluorescence-guided endoscopic optical coherence tomography

    Science.gov (United States)

    Pan, Y. T.; Xie, T. Q.; Du, C. W.; Bastacky, S.; Meyers, S.; Zeidel, M. L.

    2003-12-01

    We report an experimental study of the possibility of enhancing early bladder cancer diagnosis with fluorescence-image-guided endoscopic optical coherence tomography (OCT). After the intravesical instillation of a 10% solution of 5-aminolevulinic acid, simultaneous fluorescence imaging (excitation of 380-420 nm, emission of 620-700 nm) and OCT are performed on rat bladders to identify the photochemical and morphological changes associated with uroepithelial tumorigenesis. The preliminary results of our ex vivo study reveal that both fluorescence and OCT can identify early uroepithelial cancers, and OCT can detect precancerous lesions (e.g., hyperplasia) that fluorescence may miss. This suggests that a cystoscope combining 5-aminolevulinic acid fluorescence and OCT imaging has the potential to enhance the efficiency and sensitivity of early bladder cancer diagnosis.

  6. Coupled wave equations theory of surface-enhanced femtosecond stimulated Raman scattering.

    Science.gov (United States)

    McAnally, Michael O; McMahon, Jeffrey M; Van Duyne, Richard P; Schatz, George C

    2016-09-07

    We present a coupled wave semiclassical theory to describe plasmonic enhancement effects in surface-enhanced femtosecond stimulated Raman scattering (SE-FSRS). A key result is that the plasmon enhanced fields which drive the vibrational equation of motion for each normal mode results in dispersive lineshapes in the SE-FSRS spectrum. This result, which reproduces experimental lineshapes, demonstrates that plasmon-enhanced stimulated Raman methods provide unique sensitivity to a plasmonic response. Our derived SE-FSRS theory shows a plasmonic enhancement of |gpu|(2)ImχR(ω)gst (2)/ImχR(ω), where |gpu|(2) is the absolute square of the plasmonic enhancement from the Raman pump, χR(ω) is the Raman susceptibility, and gst is the plasmonic enhancement of the Stokes field in SE-FSRS. We conclude with a discussion on potential future experimental and theoretical directions for the field of plasmonically enhanced coherent Raman scattering.

  7. Surface enhanced Raman spectroscopy on a flat graphene surface

    Science.gov (United States)

    Xu, Weigao; Ling, Xi; Xiao, Jiaqi; Dresselhaus, Mildred S.; Kong, Jing; Xu, Hongxing; Liu, Zhongfan; Zhang, Jin

    2012-01-01

    Surface enhanced Raman spectroscopy (SERS) is an attractive analytical technique, which enables single-molecule sensitive detection and provides its special chemical fingerprints. During the past decades, researchers have made great efforts towards an ideal SERS substrate, mainly including pioneering works on the preparation of uniform metal nanostructure arrays by various nanoassembly and nanotailoring methods, which give better uniformity and reproducibility. Recently, nanoparticles coated with an inert shell were used to make the enhanced Raman signals cleaner. By depositing SERS-active metal nanoislands on an atomically flat graphene layer, here we designed a new kind of SERS substrate referred to as a graphene-mediated SERS (G-SERS) substrate. In the graphene/metal combined structure, the electromagnetic “hot” spots (which is the origin of a huge SERS enhancement) created by the gapped metal nanoislands through the localized surface plasmon resonance effect are supposed to pass through the monolayer graphene, resulting in an atomically flat hot surface for Raman enhancement. Signals from a G-SERS substrate were also demonstrated to have interesting advantages over normal SERS, in terms of cleaner vibrational information free from various metal-molecule interactions and being more stable against photo-induced damage, but with a comparable enhancement factor. Furthermore, we demonstrate the use of a freestanding, transparent and flexible “G-SERS tape” (consisting of a polymer-layer-supported monolayer graphene with sandwiched metal nanoislands) to enable direct, real time and reliable detection of trace amounts of analytes in various systems, which imparts high efficiency and universality of analyses with G-SERS substrates. PMID:22623525

  8. Cement paste surface roughness analysis using coherence scanning interferometry and confocal microscopy

    International Nuclear Information System (INIS)

    Apedo, K.L.; Munzer, C.; He, H.; Montgomery, P.; Serres, N.; Fond, C.; Feugeas, F.

    2015-01-01

    Scanning electron microscopy and scanning probe microscopy have been used for several decades to better understand the microstructure of cementitious materials. Very limited work has been performed to date to study the roughness of cementitious materials by optical microscopy such as coherence scanning interferometry (CSI) and chromatic confocal sensing (CCS). The objective of this paper is to better understand how CSI can be used as a tool to analyze surface roughness and topography of cement pastes. Observations from a series of images acquired using this technique on both polished and unpolished samples are described. The results from CSI are compared with those from a STIL confocal microscopy technique (SCM). Comparison between both optical techniques demonstrates the ability of CSI to measure both polished and unpolished cement pastes. - Highlights: • Coherence scanning interferometry (CSI) was used to analyze cement paste surfaces. • The results from the CSI were compared with those from a confocal microscopy. • 3D roughness parameters were obtained using the window resizing method. • Polished and unpolished cement pastes were studied

  9. Efficient internal and surface fingerprint extraction and blending using optical coherence tomography.

    Science.gov (United States)

    Darlow, Luke Nicholas; Connan, James

    2015-11-01

    Optical coherence tomography provides a 3D representation of fingertip skin where surface and internal fingerprints are found. These fingerprints are topographically identical. However, the surface skin is prone to damage, distortion, and spoofing; and the internal fingerprint is difficult to access and extract. This research presents a novel scaling-resolution approach to fingerprint zone detection and extraction. Furthermore, a local-quality-based blending procedure is also proposed. The accuracy of the zone-detection algorithm is comparable to an earlier work, yielding a mean-squared error of 25.9 and structural similarity of 95.8% (compared to a ground-truth estimate). Blending the surface and internal fingerprints improved the National Institute of Science and Technology's Fingerprint Image Quality scores and the average maximum match scores (when matched against conventional surface counterparts). The fingerprint blending procedure was able to combine high-quality regions from both fingerprints, thus mitigating surface wrinkles and anomalous poor-quality regions. Furthermore, spoof detection via a surface-to-internal fingerprint comparison was proposed and tested.

  10. Coherent correlation enhancement of outer shell photoionization cross sections of alkali-like ions

    International Nuclear Information System (INIS)

    Amusia, M.Y.; Avdonina, B.; Pratt, R.H.

    1995-01-01

    An alkali-like ion interaction with inner electrons of an alkali-like ion leads to a significant increase in the photoionization cross section of the outer s electron. This occurs not only for ground-state ions with one s electron in the outer shell, but also when the outer s electron is in an excited state. The reason for this amplification, in addition to coherent enhancement in summing of the correlation amplitudes, is that the zero in the direct amplitude occurs below threshold. This leads to a constructive interference with the correlation amplitude above the photoionization threshold, in contrast to a destructive interference in the case of a neutral atom with the same electronic configuration, for which the zero occurs above threshold. Results of this research were published

  11. Enhanced spectral domain optical coherence tomography for pathological and functional studies

    Science.gov (United States)

    Yuan, Zhijia

    Optical coherence tomography (OCT) is a novel technique that enables noninvasive or minimally invasive, cross-sectional imaging of biological tissue at sub-10mum spatial resolution and up to 2-3mm imaging depth. Numerous technological advances have emerged in recent years that have shown great potential to develop OCT into a powerful imaging and diagnostic tools. In particular, the implementation of Fourier-domain OCT (FDOCT) is a major step forward that leads to greatly improved imaging rate and image fidelity of OCT. This dissertation summarizes the work that focuses on enhancing the performances and functionalities of spectral radar based FDOCT (SDOCT) for pathological and functional applications. More specifically, chapters 1-4 emphasize on the development of SDOCT and its utility in pathological studies, including cancer diagnosis. The principle of SDOCT is first briefly outlined, followed by the design of our bench-top SDOCT systems with emphasis on spectral linear interpolation, calibration and system dispersion compensation. For ultrahigh-resolution SDOCT, time-lapse image registration and frame averaging is introduced to effectively reduce speckle noise and uncover subcellular details, showing great promise for enhancing the diagnosis of carcinoma in situ. To overcome the image depth limitation of OCT, a dual-modal imaging method combing SDOCT with high-frequency ultrasound is proposed and examined in animal cancer models to enhance the sensitivity and staging capabilities for bladder cancer diagnosis. Chapters 5-7 summarize the work on developing Doppler SDOCT for functional studies. Digital-frequency-ramping OCT (DFR-OCT) is developed in the study, which has demonstrated the ability to significantly improve the signal-to-noise ratio and thus sensitivity for retrieving subsurface blood flow imaging. New DFR algorithms and imaging processing methods are discussed to further enhance cortical CBF imaging. Applications of DFR-OCT for brain functional studies

  12. Speckle Noise Reduction for the Enhancement of Retinal Layers in Optical Coherence Tomography Images

    Directory of Open Access Journals (Sweden)

    Fereydoon Nowshiravan Rahatabad

    2015-09-01

    Full Text Available Introduction One of the most important pre-processing steps in optical coherence tomography (OCT is reducing speckle noise, resulting from multiple scattering of tissues, which degrades the quality of OCT images. Materials and Methods The present study focused on speckle noise reduction and edge detection techniques. Statistical filters with different masks and noise variances were applied on OCT and test images. Objective evaluation of both types of images was performed, using various image metrics such as peak signal-to-noise ratio (PSNR, root mean square error, correlation coefficient and elapsed time. For the purpose of recovery, Kuan filter was used as an input for edge enhancement. Also, a spatial filter was applied to improve image quality. Results The obtained results were presented as statistical tables and images. Based on statistical measures and visual quality of OCT images, Enhanced Lee filter (3×3 with a PSNR value of 43.6735 in low noise variance and Kuan filter (3×3 with a PSNR value of 37.2850 in high noise variance showed superior performance over other filters. Conclusion Based on the obtained results, by using speckle reduction filters such as Enhanced Lee and Kuan filters on OCT images, the number of compounded images, required to achieve a given image quality, could be reduced. Moreover, use of Kuan filters for promoting the edges allowed smoothing of speckle regions, while preserving image tissue texture.

  13. Surface magnetic enhancement for coal cleaning

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, J.Y.

    1988-01-01

    The progress achieved during this quarter includes the reagent shelf life study, the evaluation and selection of magnetizing reagents, an experimental database for activating and depressing the adsorption of magnetizing reagents in the presence of various chemicals, an adsorption regulator investigation, the establishment of a coal surface controlling theory, and a magnetite size effect study for the separation of magnetic enhanced minerals. The work is on schedule with the original plan. Modifications include the addition of a regulator study to help proving the selectivity controlling theory. The fundamentals for applying the magnetizing reagent technology on coal cleaning are generally established during this quarter. Selective magnetic enhancement of minerals through the adsorption of magnetizing reagents has been experimentally proved. The work for the next quarter will be mainly on optimizing the selective adsorption conditions and the continuation on magnetite size effect study.

  14. Development of a low-cost, 11 µm spectral domain optical coherence tomography surface profilometry prototype

    Science.gov (United States)

    Suliali, Nyasha J.; Baricholo, Peter; Neethling, Pieter H.; Rohwer, Erich G.

    2017-06-01

    A spectral-domain Optical Coherence Tomography (OCT) surface profilometry prototype has been developed for the purpose of surface metrology of optical elements. The prototype consists of a light source, spectral interferometer, sample fixture and software currently running on Microsoft® Windows platforms. In this system, a broadband light emitting diode beam is focused into a Michelson interferometer with a plane mirror as its sample fixture. At the interferometer output, spectral interferograms of broadband sources were measured using a Czerny-Turner mount monochromator with a 2048-element complementary metal oxide semiconductor linear array as the detector. The software performs importation and interpolation of interferometer spectra to pre-condition the data for image computation. One dimensional axial OCT images were computed by Fourier transformation of the measured spectra. A first reflection surface profilometry (FRSP) algorithm was then formulated to perform imaging of step-function-surfaced samples. The algorithm re-constructs two dimensional colour-scaled slice images by concatenation of 21 and 13 axial scans to form a 10 mm and 3.0 mm slice respectively. Measured spectral interferograms, computed interference fringe signals and depth reflectivity profiles were comparable to simulations and correlated to displacements of a single reflector linearly translated about the arm null-mismatch point. Surface profile images of a double-step-function-surfaced sample, embedded with inclination and crack detail were plotted with an axial resolution of 11 μm. The surface shape, defects and misalignment relative to the incident beam were detected to the order of a micron, confirming high resolution of the developed system as compared to electro-mechanical surface profilometry techniques.

  15. Local processing enhancements associated with superior observational drawing are due to enhanced perceptual functioning, not weak central coherence.

    Science.gov (United States)

    Chamberlain, Rebecca; McManus, I C; Riley, Howard; Rankin, Qona; Brunswick, Nicola

    2013-01-01

    Individuals with drawing talent have previously been shown to exhibit enhanced local visual processing ability. The aim of the current study was to assess whether local processing biases associated with drawing ability result from a reduced ability to cohere local stimuli into global forms, or an increased ability to disregard global aspects of an image. Local and global visual processing ability was assessed in art students and controls using the Group Embedded Figures Task, Navon shape stimuli, the Block Design Task and the Autism Spectrum Quotient, whilst controlling for nonverbal IQ and artistic ability. Local processing biases associated with drawing appear to arise from an enhancement of local processing alongside successful filtering of global information, rather than a reduction in global processing. The relationship between local processing and drawing ability is independent of individual differences in nonverbal IQ and artistic ability. These findings have implications for bottom-up and attentional theories of observational drawing, as well as explanations of special skills in autism.

  16. Electron emission induced by resonant coherent interaction in ion-surface scattering at grazing incidence

    International Nuclear Information System (INIS)

    Garcia de Abajo, F.J.; Ponce, V.H.; Echenique, P.M.

    1994-01-01

    The resonant coherent interaction of an ion with an oriented crystal surface, under grazing-incidence conditions with respect to a special direction of the crystal, gives rise to electron loss to the continuum from electronic bound states of the ion. The calculations presented below predict large probabilities for electron emission due to this mechanism. The electrons are emitted with well defined energies, expressed in terms of the condition of resonance. Furthermore, the emission takes place around certain preferential directions, which are determined by both the latter condition and the symmetry of the surface lattice. Our calculations for MeV He + ions scattered at a W(001) surface along the left-angle 100 right-angle direction with glancing angle of 0--2 mrad indicate a yield of emission close to 1. Using heavier projectiles, one obtains smaller yields, but still large enough to be measurable in some cases (e.g., ∼0.9 for 53 MeV B 4+ and an angle of incidence of 1 mrad). Besides, the initial bound state is energy shifted due to the interaction with both the crystal potential and the velocity-dependent image potential. This results in a slight shift of the peaks of emission, which suggests a possible spectroscopy for analyzing the dynamical interaction of electronic bound states with solid surfaces

  17. Enhanced depth imaging optical coherence tomography of the sclera in dome-shaped macula.

    Science.gov (United States)

    Imamura, Yutaka; Iida, Tomohiro; Maruko, Ichiro; Zweifel, Sandrine A; Spaide, Richard F

    2011-02-01

    To examine the posterior anatomic structure of eyes with dome-shaped macula using enhanced depth imaging spectral-domain optical coherence tomography (EDI-OCT). Retrospective observational case series. Patients with dome-shaped macula, a condition defined as convex elevation of the macula as compared with the surrounding staphylomatous region in a highly myopic eye, were identified through routine examinations using optical coherence tomography (OCT). EDI-OCT was used to examine their posterior anatomic changes. The scleral thickness was measured from the outer border of the choroid to the outer scleral border under the fovea and 3000 μm temporal to the fovea. The mean age of the 15 patients (23 eyes) was 59.3 (± 12.2) years, and the mean refractive error was -13.6 (± 5.0) diopters. The best-corrected visual acuity ranged from 20/15 to 20/800 (median: 20/30). Eight patients (53%) had dome-shaped macula bilaterally. The mean subfoveal scleral thickness in 23 eyes with dome-shaped macula was 570 (± 221) μm, and that in 25 eyes of 15 myopic patients with staphyloma but without dome-shaped macula was 281 (± 85) μm (P macula is the result of a relative localized thickness variation of the sclera under the macula in highly myopic patients, and it cannot be categorized into any of the known types of staphyloma. This finding suggests the ocular expansion in myopia may be more complex than previously thought. Copyright © 2011 Elsevier Inc. All rights reserved.

  18. Passive Frequency Selective Surface Array as a Diffuser for Destroying Millimeter Wave Coherence

    Directory of Open Access Journals (Sweden)

    Saiful Islam

    2008-01-01

    Full Text Available This paper presents the design, construction, and testing of grounded frequency selective surface (FSS array as a diffuser for destroying millimeter wave coherence which is used to eliminate speckle in active millimeter wave imaging. To create stochastically independent illumination patterns, we proposed a diffuser based on random-phase distributions obtained by changing the incident frequency. The random-phase diffuser was obtained by mixing up the phase relations between the cells of a deterministic function (e.g., beam splitter. The slot length of FSS is the main design parameter used to optimize the phase shifting properties of the array. The critical parameters of the diffuser array design, such as phase relation with slot lengths, losses, and bandwidth, are discussed. We designed the FSS arrays with finite integral technique (FIT, fabricated by etching technique, and characterized the S-parameters with a free-space MVNA, and measured the radiation patterns with a BWO in motorized setup.

  19. SUBMILLIMETER CHOROIDAL MELANOMA DETECTION BY ENHANCED DEPTH IMAGING OPTICAL COHERENCE TOMOGRAPHY IN A PATIENT WITH OCULODERMAL MELANOCYTOSIS.

    Science.gov (United States)

    Daitch, Zachary; Shields, Carol L; Say, Emil A T; Mashayekhi, Arman; Shields, Jerry A

    2016-01-01

    To describe a tiny subclinical choroidal melanoma visualized only with enhanced depth imaging optical coherence tomography in a newly symptomatic patient with known oculodermal melanocytosis. Case report. A 52-year-old white man with heterochromia and known oculodermal melanocytosis of the right eye, followed for 2 years without change, developed blurred vision and was referred for possible central serous chorioretinopathy. On examination, visual acuity was 20/20 in each eye. There was oculodermal melanocytosis in the right eye involving the periocular skin, episclera, iris, and choroid. On ophthalmoscopy and ocular ultrasonography, there was no appreciable mass, but subtle subfoveal fluid and perifoveal orange pigment were detected, as well as equatorial drusen. Enhanced depth imaging optical coherence tomography demonstrated a subtle optically dense focal choroidal mass measuring 4.5 mm in basal dimension and 0.7 mm in enhanced depth imaging optical coherence tomography thickness. There was choroidal vascular compression, obliteration of choroidal details, and related overlying subretinal fluid with shaggy photoreceptors, consistent with early choroidal melanoma in an eye with oculodermal melanocytosis. The patient elected early treatment considering the risk factors for growth and the risk for metastasis associated with melanoma in the setting of oculodermal melanocytosis. Plaque radiotherapy was performed with complete tumor regression clinically and by enhanced depth imaging optical coherence tomography. At 2-year follow-up, visual acuity remains 20/20, with regressed tumor and no systemic metastasis. Enhanced depth imaging optical coherence tomography is a useful tool in the evaluation of eyes with oculodermal melanocytosis, permitting high-resolution visualization of the choroid and detection of submillimeter early melanoma that might not be apparent with indirect ophthalmoscopy or ultrasonography.

  20. Formation of surface nanolayers in chalcogenide crystals using coherent laser beams

    Science.gov (United States)

    Ozga, K.; Fedorchuk, A. O.; El-Naggar, A. M.; Albassam, A. A.; Kityk, V.

    2018-03-01

    We have shown a possibility to form laser modified surface nanolayers with thickness up to 60 nm in some ternary chalcogenide crystals (Ag3AsS3, Ag3SbS3, Tl3SbS3) The laser treatment was performed by two coherent laser beams split in a space. As the inducing lasers we have applied continuous wave (cw) Hesbnd Cd laser at wavelength 441 nm and doubled frequency cw Nd: YAG laser at 532 nm. The spectral energies of these lasers were higher with respect to the energy gaps of the studied crystals. The optical anisotropy was appeared and defected by monitoring of birefringence at probing wavelength of cw Hesbnd Ne laser at λ = 3390 nm. The changes of the laser stimulated near the surface layer morphology was monitored by TEM and AFM methods as well as by the reflected optical second harmonic generation at fundamental wavelength of microsecond CO2 laser generating at wavelength 10600 nm. This technique may open a new approach for the formation of the near the surface nanolayers in chalcogenides using external cw laser illumination.

  1. Scrambled coherent superposition for enhanced optical fiber communication in the nonlinear transmission regime.

    Science.gov (United States)

    Liu, Xiang; Chandrasekhar, S; Winzer, P J; Chraplyvy, A R; Tkach, R W; Zhu, B; Taunay, T F; Fishteyn, M; DiGiovanni, D J

    2012-08-13

    Coherent superposition of light waves has long been used in various fields of science, and recent advances in digital coherent detection and space-division multiplexing have enabled the coherent superposition of information-carrying optical signals to achieve better communication fidelity on amplified-spontaneous-noise limited communication links. However, fiber nonlinearity introduces highly correlated distortions on identical signals and diminishes the benefit of coherent superposition in nonlinear transmission regime. Here we experimentally demonstrate that through coordinated scrambling of signal constellations at the transmitter, together with appropriate unscrambling at the receiver, the full benefit of coherent superposition is retained in the nonlinear transmission regime of a space-diversity fiber link based on an innovatively engineered multi-core fiber. This scrambled coherent superposition may provide the flexibility of trading communication capacity for performance in future optical fiber networks, and may open new possibilities in high-performance and secure optical communications.

  2. Role of high resolution optical coherence tomography in diagnosing ocular surface squamous neoplasia with coexisting ocular surface diseases.

    Science.gov (United States)

    Atallah, Marwan; Joag, Madhura; Galor, Anat; Amescua, Guillermo; Nanji, Afshan; Wang, Jianhua; Perez, Victor L; Dubovy, Sander; Karp, Carol L

    2017-10-01

    Coexistence of an ocular surface disease can mask the typical features of ocular surface squamous neoplasia (OSSN). The purpose of this study was to evaluate high resolution optical coherence tomography (HR-OCT) as an adjunct in the detection and differentiation of OSSN within coexisting ocular surface pathologies. Retrospective study of 16 patients with ocular surface disease and lesions suspicious for OSSN that were evaluated with HR-OCT. HR-OCT images of the lesions were taken to look for evidence of OSSN. Biopsies were performed in all cases, and the HR-OCT findings were compared to the histological results. Of the 16 patients with OSSN and a coexisting ocular surface disease, 12 were found to have OSSN by HR-OCT and all were subsequently confirmed by biopsy. Two patients had OSSN with rosacea, one with pingueculum, two within pterygia, one with Salzmann' nodular degeneration, six with limbal stem cell deficiency (LSCD)/scarring. In all 12 cases HR-OCT images revealed classical findings of hyper-reflective, thickened epithelium and an abrupt transition from normal to abnormal epithelium. OSSN was ruled out by HR-OCT in four cases (2 Salzmann's, 1 mucous membrane pemphigoid, and 1 LSCD). Negative findings were confirmed by biopsy. HR-OCT was used to follow resolution of the OSSN in positive cases, and it detected recurrence in 1 case. While histopathology is the gold standard in the diagnosis of OSSN, HR-OCT can be used to noninvasively detect the presence of OSSN in patients with coexisting ocular conditions. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Enhanced depth imaging optical coherence tomography and fundus autofluorescence findings in bilateral choroidal osteoma: a case report

    Energy Technology Data Exchange (ETDEWEB)

    Erol, Muhammet Kazim; Coban, Deniz Turgut; Ceran, Basak Bostanci; Bulut, Mehmet, E-mail: muhammetkazimerol@gmail.com [Kazim Erol. Antalya Training and Research Hospital, Ophthalmology Department, Antalya (Turkey)

    2013-11-01

    The authors present enhanced depth imaging optical coherence tomography (EDI OCT) and fundus autofluorescence (FAF) characteristics of a patient with bilateral choroidal osteoma and try to make a correlation between two imaging techniques. Two eyes of a patient with choroidal osteoma underwent complete ophthalmic examination. Enhanced depth imaging optical coherence tomography revealed a cage-like pattern, which corresponded to the calcified region of the tumor. Fundus autofluorescence imaging of the same area showed slight hyperautofluorescence. Three different reflectivity patterns in the decalcified area were defined. In the areas of subretinal fluid, outer segment elongations similar to central serous chorioretinopathy were observed. Hyperautofluorescent spots were evident in fundus autofluorescence in the same area. Calcified and decalcified portions of choroidal osteoma as well as the atrophy of choriocapillaris demonstrated different patterns with enhanced depth imaging and fundus autofluorescence imaging. Both techniques were found to be beneficial in the diagnosis and follow-up of choroidal osteoma. (author)

  4. Enhanced depth imaging optical coherence tomography and fundus autofluorescence findings in bilateral choroidal osteoma: a case report

    Directory of Open Access Journals (Sweden)

    Muhammet Kazim Erol

    2013-06-01

    Full Text Available The authors present enhanced depth imaging optical coherence tomography (EDI OCT and fundus autofluorescence (FAF characteristics of a patient with bilateral choroidal osteoma and try to make a correlation between two imaging techniques. Two eyes of a patient with choroidal osteoma underwent complete ophthalmic examination. Enhanced depth imaging optical coherence tomography revealed a cage-like pattern, which corresponded to the calcified region of the tumor. Fundus autofluorescence imaging of the same area showed slight hyperautofluorescence. Three different reflectivity patterns in the decalcified area were defined. In the areas of subretinal fluid, outer segment elongations similar to central serous chorioretinopathy were observed. Hyperautofluorescent spots were evident in fundus autofluorescence in the same area. Calcified and decalcified portions of choroidal osteoma as well as the atrophy of choriocapillaris demonstrated different patterns with enhanced depth imaging and fundus autofluorescence imaging. Both techniques were found to be beneficial in the diagnosis and follow-up of choroidal osteoma.

  5. Evidence for Neural Computations of Temporal Coherence in an Auditory Scene and Their Enhancement during Active Listening.

    Science.gov (United States)

    O'Sullivan, James A; Shamma, Shihab A; Lalor, Edmund C

    2015-05-06

    The human brain has evolved to operate effectively in highly complex acoustic environments, segregating multiple sound sources into perceptually distinct auditory objects. A recent theory seeks to explain this ability by arguing that stream segregation occurs primarily due to the temporal coherence of the neural populations that encode the various features of an individual acoustic source. This theory has received support from both psychoacoustic and functional magnetic resonance imaging (fMRI) studies that use stimuli which model complex acoustic environments. Termed stochastic figure-ground (SFG) stimuli, they are composed of a "figure" and background that overlap in spectrotemporal space, such that the only way to segregate the figure is by computing the coherence of its frequency components over time. Here, we extend these psychoacoustic and fMRI findings by using the greater temporal resolution of electroencephalography to investigate the neural computation of temporal coherence. We present subjects with modified SFG stimuli wherein the temporal coherence of the figure is modulated stochastically over time, which allows us to use linear regression methods to extract a signature of the neural processing of this temporal coherence. We do this under both active and passive listening conditions. Our findings show an early effect of coherence during passive listening, lasting from ∼115 to 185 ms post-stimulus. When subjects are actively listening to the stimuli, these responses are larger and last longer, up to ∼265 ms. These findings provide evidence for early and preattentive neural computations of temporal coherence that are enhanced by active analysis of an auditory scene. Copyright © 2015 the authors 0270-6474/15/357256-08$15.00/0.

  6. Morphometric features on enhanced depth imaging optical coherence tomography scans in idiopathic posterior uveitis or panuveitis.

    Science.gov (United States)

    Agrawal, Rupesh; Arora, Rashi; Keane, Pearse A; Agarwal, Aniruddha; Pavesio, Carlos

    2017-06-05

    Enhanced depth imaging (EDI) optical coherence tomography (OCT) has emerged as a novel tool for qualitative and quantitative choroidal assessment in posterior uveitis. The objective of this study was to investigate the role of EDI-OCT to assess the choroidal and retinal changes in posterior uveitis. In this retrospective study, EDI-OCT scans of patients with idiopathic posterior uveitis or panuveitis were reviewed. Morphological features from retina and choroid from the OCT scans were assessed and compared to the fellow normal eyes. Follow-up assessment was performed at 6-month follow-up. Nineteen patients with idiopathic posterior or panuveitis were included in the study. Choroidal examination using EDI-OCT scans showed areas of focal hypo-reflective and discrete hyper-reflective foci in one-third patients. Macular edema, disruption of the ellipsoid zone (generalized and discrete), outer retinal hyper-reflective foci, and intraretinal and subretinal fluid were observed. The index study reports qualitative OCT-derived parameters as possible tools in monitoring disease progression in uveitis.

  7. Four-dimensional microscope- integrated optical coherence tomography to enhance visualization in glaucoma surgeries.

    Science.gov (United States)

    Pasricha, Neel Dave; Bhullar, Paramjit Kaur; Shieh, Christine; Viehland, Christian; Carrasco-Zevallos, Oscar Mijail; Keller, Brenton; Izatt, Joseph Adam; Toth, Cynthia Ann; Challa, Pratap; Kuo, Anthony Nanlin

    2017-01-01

    We report the first use of swept-source microscope-integrated optical coherence tomography (SS-MIOCT) capable of live four-dimensional (4D) (three-dimensional across time) imaging intraoperatively to directly visualize tube shunt placement and trabeculectomy surgeries in two patients with severe open-angle glaucoma and elevated intraocular pressure (IOP) that was not adequately managed by medical intervention or prior surgery. We performed tube shunt placement and trabeculectomy surgery and used SS-MIOCT to visualize and record surgical steps that benefitted from the enhanced visualization. In the case of tube shunt placement, SS-MIOCT successfully visualized the scleral tunneling, tube shunt positioning in the anterior chamber, and tube shunt suturing. For the trabeculectomy, SS-MIOCT successfully visualized the scleral flap creation, sclerotomy, and iridectomy. Postoperatively, both patients did well, with IOPs decreasing to the target goal. We found the benefit of SS-MIOCT was greatest in surgical steps requiring depth-based assessments. This technology has the potential to improve clinical outcomes.

  8. Enhanced Lithium-ion intercalation properties of coherent hydrous vanadium pentoxide-carbon cryogels nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Anqiang; Liu, Dawei; Zhou, Xiaoyuan; Garcia, Betzaita Betalla; Liang, Shu-quan; Liu, Jun; Cao, Guozhong

    2010-06-01

    Coherent hydrous vanadium pentoxide (V2O5•nH2O) - carbon cryogels (CCs) nanocomposites were synthesized by electrodeposition of vanadium pentoxide onto the porous carbon scaffold which was derived from resorcinol (R) and formaldehyde (F) organic hydrogels. As-fabricated nanocomposites were characterized by scanning electron microscopy (SEM), along with EDAX and nitrogen sorption isotherms which suggested vanadium pentoxide incorporated in the pores of carbon cryogels. The nanocomposites showed much improved discharge capacity and better cyclic stability as compared to hydrous vanadium pentoxide films deposited on platinum foil. The discharge capacity of the nanocomposites reached 280 mAh/g based on the mass of the vandium pentoxide at a current density of 100mA/g and it possessed good cycle stability at different discharge rate. The results demonstrated that electrochemical performances, such as specific discharge capacitance and reversibility of the composite electrode, could be greatly enhanced by the introduction of carbon cryogels (CCs) scaffold with three-dimensionally interconnected porous structure in which V2O5•nH2O homogeneously dispersed.

  9. Quantum Coherence Times Enhancement in Vanadium(IV)-based Potential Molecular Qubits: the Key Role of the Vanadyl Moiety.

    Science.gov (United States)

    Atzori, Matteo; Morra, Elena; Tesi, Lorenzo; Albino, Andrea; Chiesa, Mario; Sorace, Lorenzo; Sessoli, Roberta

    2016-09-07

    In the search for long-lived quantum coherence in spin systems, vanadium(IV) complexes have shown record phase memory times among molecular systems. When nuclear spin-free ligands are employed, vanadium(IV) complexes can show at low temperature sufficiently long quantum coherence times, Tm, to perform quantum operations, but their use in real devices operating at room temperature is still hampered by the rapid decrease of T1 caused by the efficient spin-phonon coupling. In this work we have investigated the effect of different coordination environments on the magnetization dynamics and the quantum coherence of two vanadium(IV)-based potential molecular spin qubits in the solid state by introducing a unique structural difference, i.e., an oxovanadium(IV) in a square pyramidal versus a vanadium(IV) in an octahedral environment featuring the same coordinating ligand, namely, the 1,3-dithiole-2-thione-4,5-dithiolate. This investigation, performed by a combined approach of alternate current (ac) susceptibility measurements and continuous wave (CW) and pulsed electron paramagnetic resonance (EPR) spectroscopies revealed that the effectiveness of the vanadyl moiety in enhancing quantum coherence up to room temperature is related to a less effective mechanism of spin-lattice relaxation that can be quantitatively evaluated by the exponent n (ca. 3) of the temperature dependence of the relaxation rate. A more rapid collapse is observed for the non-oxo counterpart (n = 4) hampering the observation of quantum coherence at room temperature. Record coherence time at room temperature (1.04 μs) and Rabi oscillations are also observed for the vanadyl derivative in a very high concentrated material (5 ± 1%) as a result of the additional benefit provided by the use of a nuclear spin-free ligand.

  10. Enhanced vitreous imaging in healthy eyes using swept source optical coherence tomography.

    Science.gov (United States)

    Liu, Jonathan J; Witkin, Andre J; Adhi, Mehreen; Grulkowski, Ireneusz; Kraus, Martin F; Dhalla, Al-Hafeez; Lu, Chen D; Hornegger, Joachim; Duker, Jay S; Fujimoto, James G

    2014-01-01

    To describe enhanced vitreous imaging for visualization of anatomic features and microstructures within the posterior vitreous and vitreoretinal interface in healthy eyes using swept-source optical coherence tomography (SS-OCT). The study hypothesis was that long-wavelength, high-speed, volumetric SS-OCT with software registration motion correction and vitreous window display or high-dynamic-range (HDR) display improves detection sensitivity of posterior vitreous and vitreoretinal features compared to standard OCT logarithmic scale display. Observational prospective cross-sectional study. Multiple wide-field three-dimensional SS-OCT scans (500×500A-scans over 12×12 mm2) were obtained using a prototype instrument in 22 eyes of 22 healthy volunteers. A registration motion-correction algorithm was applied to compensate motion and generate a single volumetric dataset. Each volumetric dataset was displayed in three forms: (1) standard logarithmic scale display, enhanced vitreous imaging using (2) vitreous window display and (3) HDR display. Each dataset was reviewed independently by three readers to identify features of the posterior vitreous and vitreoretinal interface. Detection sensitivities for these features were measured for each display method. Features observed included the bursa premacularis (BPM), area of Martegiani, Cloquet's/BPM septum, Bergmeister papilla, posterior cortical vitreous (hyaloid) detachment, papillomacular hyaloid detachment, hyaloid attachment to retinal vessel(s), and granular opacities within vitreous cortex, Cloquet's canal, and BPM. The detection sensitivity for these features was 75.0% (95%CI: 67.8%-81.1%) using standard logarithmic scale display, 80.6% (95%CI: 73.8%-86.0%) using HDR display, and 91.9% (95%CI: 86.6%-95.2%) using vitreous window display. SS-OCT provides non-invasive, volumetric and measurable in vivo visualization of the anatomic microstructural features of the posterior vitreous and vitreoretinal interface. The

  11. Enhanced vitreous imaging in healthy eyes using swept source optical coherence tomography.

    Directory of Open Access Journals (Sweden)

    Jonathan J Liu

    Full Text Available To describe enhanced vitreous imaging for visualization of anatomic features and microstructures within the posterior vitreous and vitreoretinal interface in healthy eyes using swept-source optical coherence tomography (SS-OCT. The study hypothesis was that long-wavelength, high-speed, volumetric SS-OCT with software registration motion correction and vitreous window display or high-dynamic-range (HDR display improves detection sensitivity of posterior vitreous and vitreoretinal features compared to standard OCT logarithmic scale display.Observational prospective cross-sectional study.Multiple wide-field three-dimensional SS-OCT scans (500×500A-scans over 12×12 mm2 were obtained using a prototype instrument in 22 eyes of 22 healthy volunteers. A registration motion-correction algorithm was applied to compensate motion and generate a single volumetric dataset. Each volumetric dataset was displayed in three forms: (1 standard logarithmic scale display, enhanced vitreous imaging using (2 vitreous window display and (3 HDR display. Each dataset was reviewed independently by three readers to identify features of the posterior vitreous and vitreoretinal interface. Detection sensitivities for these features were measured for each display method.Features observed included the bursa premacularis (BPM, area of Martegiani, Cloquet's/BPM septum, Bergmeister papilla, posterior cortical vitreous (hyaloid detachment, papillomacular hyaloid detachment, hyaloid attachment to retinal vessel(s, and granular opacities within vitreous cortex, Cloquet's canal, and BPM. The detection sensitivity for these features was 75.0% (95%CI: 67.8%-81.1% using standard logarithmic scale display, 80.6% (95%CI: 73.8%-86.0% using HDR display, and 91.9% (95%CI: 86.6%-95.2% using vitreous window display.SS-OCT provides non-invasive, volumetric and measurable in vivo visualization of the anatomic microstructural features of the posterior vitreous and vitreoretinal interface. The

  12. Plasmonic nanostructures for surface enhanced spectroscopic methods.

    Science.gov (United States)

    Jahn, Martin; Patze, Sophie; Hidi, Izabella J; Knipper, Richard; Radu, Andreea I; Mühlig, Anna; Yüksel, Sezin; Peksa, Vlastimil; Weber, Karina; Mayerhöfer, Thomas; Cialla-May, Dana; Popp, Jürgen

    2016-02-07

    A comprehensive review of theoretical approaches to simulate plasmonic-active metallic nano-arrangements is given. Further, various fabrication methods based on bottom-up, self-organization and top-down techniques are introduced. Here, analytical approaches are discussed to investigate the optical properties of isotropic and non-magnetic spherical or spheroidal particles. Furthermore, numerical methods are introduced to research complex shaped structures. A huge variety of fabrication methods are reviewed, e.g. bottom-up preparation strategies for plasmonic nanostructures to generate metal colloids and core-shell particles as well as complex-shaped structures, self-organization as well as template-based methods and finally, top-down processes, e.g. electron beam lithography and its variants as well as nanoimprinting. The review article is aimed at beginners in the field of surface enhanced spectroscopy (SES) techniques and readers who have a general interest in theoretical modelling of plasmonic substrates for SES applications as well as in the fabrication of the desired structures based on methods of the current state of the art.

  13. Coherent structures in stratocumulus topped boundary layer: sensitivity to surface fluxes, radiative cooling and vertical stability

    Science.gov (United States)

    Davini, Paolo; D'Andrea, Fabio; Park, Seung-bu; Gentine, Pierre

    2017-04-01

    The representation of stratocumulus clouds in global climate models is still a concern for the climate modelling community. This is due to the low efficacy of current parametrization to simulate the full set of phenomena that governs the stratocumulus topped boundary layer (STBL), but also by the inaccurate knowledge of the sensitivities of the STBL dynamics to external large scale forcing. Here we show that making of a series of high-resolution LES simulations, we are able to detect and track coherent structures such as updrafts, downdrafts and their returning shells (i.e. both ascending and subsiding), together with the entraining air from the inversion layer or the free troposphere in a non-precipitating marine nighttime STBL. This is done with a new classification method based on octant analysis - using vertical velocity and two passive scalars - which defines the structures also in cloud-free regions. We are thus able to quantify the geometrical and thermodynamic characteristics (e.g. areal fraction, temperature, liquid and total water mixing ratio, buoyancy, etc.) of those structures, highlighting the single contributions to the turbulent transport of mass, heat and moisture. It is thus possible to estimate the sensitivity of the turbulent fluxes to the intensity of the cloud-top radiative cooling, to the surface latent and sensible fluxes and to the strength of the vertical stability is explored. Indeed, this analysis lays the foundation for a new parametrization of stratocumulus-topped boundary layer for global climate models.

  14. Choroidal vasculature characteristics based choroid segmentation for enhanced depth imaging optical coherence tomography images

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Qiang; Niu, Sijie [School of Computer Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Yuan, Songtao; Fan, Wen, E-mail: fanwen1029@163.com; Liu, Qinghuai [Department of Ophthalmology, The First Affiliated Hospital with Nanjing Medical University, Nanjing 210029 (China)

    2016-04-15

    Purpose: In clinical research, it is important to measure choroidal thickness when eyes are affected by various diseases. The main purpose is to automatically segment choroid for enhanced depth imaging optical coherence tomography (EDI-OCT) images with five B-scans averaging. Methods: The authors present an automated choroid segmentation method based on choroidal vasculature characteristics for EDI-OCT images with five B-scans averaging. By considering the large vascular of the Haller’s layer neighbor with the choroid-sclera junction (CSJ), the authors measured the intensity ascending distance and a maximum intensity image in the axial direction from a smoothed and normalized EDI-OCT image. Then, based on generated choroidal vessel image, the authors constructed the CSJ cost and constrain the CSJ search neighborhood. Finally, graph search with smooth constraints was utilized to obtain the CSJ boundary. Results: Experimental results with 49 images from 10 eyes in 8 normal persons and 270 images from 57 eyes in 44 patients with several stages of diabetic retinopathy and age-related macular degeneration demonstrate that the proposed method can accurately segment the choroid of EDI-OCT images with five B-scans averaging. The mean choroid thickness difference and overlap ratio between the authors’ proposed method and manual segmentation drawn by experts were −11.43 μm and 86.29%, respectively. Conclusions: Good performance was achieved for normal and pathologic eyes, which proves that the authors’ method is effective for the automated choroid segmentation of the EDI-OCT images with five B-scans averaging.

  15. Diagnostic capability of scanning laser polarimetry with and without enhanced corneal compensation and optical coherence tomography.

    Science.gov (United States)

    Benítez-del-Castillo, Javier; Martinez, Antonio; Regi, Teresa

    2011-01-01

    To compare the abilities of the current commercially available versions of scanning laser polarimetry (SLP) and optical coherence tomography (OCT), SLP-variable corneal compensation (VCC), SLP-enhanced corneal compensation (ECC), and high-definition (HD) OCT, in discriminating between healthy eyes and those with early-to-moderate glaucomatous visual field loss. Healthy volunteers and patients with glaucoma who met the eligibility criteria were consecutively enrolled in this prospective, cross-sectional, observational study. Subjects underwent complete eye examination, automated perimetry, SLP-ECC, SLP-VCC, and HD-OCT. Scanning laser polarimetry parameters were recalculated in 90-degree segments (quadrants) in the calculation circle to be compared. Areas under the receiver operating characteristic curve (AUROCs) were calculated for every parameter in order to compare the ability of each imaging modality to differentiate between normal and glaucomatous eyes. Fifty-five normal volunteers (mean age 59.1 years) and 33 patients with glaucoma (mean age 63.8 years) were enrolled. Average visual field mean deviation was -6.69 dB (95% confidence interval -8.07 to -5.31) in the glaucoma group. The largest AUROCs were associated with nerve fiber indicator (0.880 and 0.888) for the SLP-VCC and SLP-ECC, respectively, and with the average thickness in the HD-OCT (0.897). The best performing indices for the SLP-VCC, SLP-ECC, and HD OCT gave similar AUROCs, showing moderate diagnostic accuracy in patients with early to moderate glaucoma. Further studies are needed to evaluate the ability of these technologies to discriminate between normal and glaucomatous eyes.

  16. Multilayered disease-mimicking bladder phantom with realistic surface topology for optical coherence tomography

    Science.gov (United States)

    Smith, Gennifer T.; Lurie, Kristen L.; Khan, Saara A.; Liao, Joseph C.; Ellerbee, Audrey K.

    2014-03-01

    Optical coherence tomography (OCT) has shown potential as a complementary modality to white light cystoscopy (WLC), the gold standard for imaging bladder cancer. OCT can visualize sub-surface details of the bladder wall, which enables it to stage cancers and detect tumors that are otherwise invisible to WLC. Currently, OCT systems have too slow a speed and too small a field of view for comprehensive bladder imaging, which limits its clinical utility. Validation and feasibility testing of technological refinements aimed to provide faster imaging and wider fields of view necessitates a realistic bladder phantom. We present a novel process to fabricate the first such phantom that mimics both the optical and morphological properties of layers of the healthy and pathologic bladder wall as they characteristically appear with OCT. The healthy regions of the silicone-based phantom comprises three layers: the urothelium, lamina propria and muscularis propria, each containing an appropriate concentration of titanium dioxide to mimic its distinct scattering properties. As well, the layers each possess a unique surface appearance imposed by a textured mold. Within this phantom, pathologic tissue-mimicking regions are created by thickening specific layers or creating inclusions that disrupt the layered appearance of the bladder wall, as is characteristic of bladder carcinomas. This phantom can help to evaluate the efficacy of new OCT systems and software for tumor localization. Moreover, the procedure we have developed is highly generalizable for the creation of OCT-relevant, multi-layer phantoms for tissues that incorporate diseased states characterized by the loss of layered structures.

  17. Effects of collisions on electronic-resonance-enhanced coherent anti-Stokes Raman scattering of nitric oxide

    Science.gov (United States)

    Patnaik, Anil K.; Roy, Sukesh; Gord, James R.; Lucht, Robert P.; Settersten, Thomas B.

    2009-06-01

    A six-level model is developed and used to study the effects of collisional energy transfer and dephasing on electronic-resonance-enhanced coherent anti-Stokes Raman scattering (ERE-CARS) in nitric oxide. The model includes the three levels that are coherently coupled by the three applied lasers as well as three additional bath levels that enable inclusion of the effects of electronic quenching and rotational energy transfer. The density-matrix equations that describe the evolution of the relevant populations and coherences are presented. The parametric dependencies of the ERE-CARS signal on collisional energy transfer and dephasing processes are described in terms of both a steady-state analytical solution and the numerical solutions to the governing equations. In the weak-field limit, the ERE-CARS signal scales inversely with the square of the dephasing rates for the electronic and Raman coherences. In accord with published experimental observations [Roy et al., Appl. Phys. Lett. 89, 104105 (2006)], the ERE-CARS signal is shown to be insensitive to the collisional quenching rate. Parametric dependencies on quenching, rotational energy transfer, and pure electronic dephasing are presented, demonstrating reduced collisional dependence for saturating laser fields.

  18. Long Term 1 Enhanced Surface Water Treatment Rule Documents

    Science.gov (United States)

    The Long Term 1 Enhanced Surface Water Treatment Rule (LT1ESWTR) builds on the requirements of the Surface Water Treatment Rule and specifies treatment requirements to address Cryptosporidium m and other microbial contaminants in public water systems.

  19. Application of random coherence order selection in gradient-enhanced multidimensional NMR

    International Nuclear Information System (INIS)

    Bostock, Mark J.; Nietlispach, Daniel

    2016-01-01

    Development of multidimensional NMR is essential to many applications, for example in high resolution structural studies of biomolecules. Multidimensional techniques enable separation of NMR signals over several dimensions, improving signal resolution, whilst also allowing identification of new connectivities. However, these advantages come at a significant cost. The Fourier transform theorem requires acquisition of a grid of regularly spaced points to satisfy the Nyquist criterion, while frequency discrimination and acquisition of a pure phase spectrum require acquisition of both quadrature components for each time point in every indirect (non-acquisition) dimension, adding a factor of 2 N -1 to the number of free- induction decays which must be acquired, where N is the number of dimensions. Compressed sensing (CS) ℓ 1 -norm minimisation in combination with non-uniform sampling (NUS) has been shown to be extremely successful in overcoming the Nyquist criterion. Previously, maximum entropy reconstruction has also been used to overcome the limitation of frequency discrimination, processing data acquired with only one quadrature component at a given time interval, known as random phase detection (RPD), allowing a factor of two reduction in the number of points for each indirect dimension (Maciejewski et al. 2011 PNAS 108 16640). However, whilst this approach can be easily applied in situations where the quadrature components are acquired as amplitude modulated data, the same principle is not easily extended to phase modulated (P-/N-type) experiments where data is acquired in the form exp (iωt) or exp (-iωt), and which make up many of the multidimensional experiments used in modern NMR. Here we demonstrate a modification of the CS ℓ 1 -norm approach to allow random coherence order selection (RCS) for phase modulated experiments; we generalise the nomenclature for RCS and RPD as random quadrature detection (RQD). With this method, the power of RQD can be extended

  20. Surface engineering for enhanced performance against wear

    CERN Document Server

    2013-01-01

    Surface Engineering constitutes a variety of processes and sub processes. Each chapter of this work covers specific processes by experts working in the area. Included for each topic are tribological performances for each process as well as results of recent research. The reader also will benefit from in-depth studies of diffusion coatings, nanocomposite films for wear resistance, surfaces for biotribological applications, thin-film wear, tribology of thermal sprayed coatings, hardfacing, plating for tribology and high energy beam surface modifications. Material scientists as well as engineers working with surface engineering for tribology will be particularly interested in this work.

  1. Enhanced terahertz emission by coherent optical absorption in ultrathin semiconductor films on metals

    NARCIS (Netherlands)

    Ramakrishnan, G.; Ramanandan, G.K.P.; Adam, A.J.L.; Xu, M.; Kumar, N.; Hendrikx, R.W.A.; Planken, P.C.M.

    2013-01-01

    We report on the surprisingly strong, broadband emission of coherent terahertz pulses from ultrathin layers of semiconductors such as amorphous silicon, germanium and polycrystalline cuprous oxide deposited on gold, upon illumination with femtosecond laser pulses. The strength of the emission is

  2. In-situ monitoring of surface post-processing in large aperture fused silica optics with Optical Coherence Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Guss, G M; Bass, I l; Hackel, R P; Mailhiot, C; Demos, S G

    2008-02-08

    Optical Coherence Tomography is explored as a method to image laser-damage sites located on the surface of large aperture fused silica optics during post-processing via CO{sub 2} laser ablation. The signal analysis for image acquisition was adapted to meet the sensitivity requirements for this application. A long-working distance geometry was employed to allow imaging through the opposite surface of the 5-cm thick optic. The experimental results demonstrate the potential of OCT for remote monitoring of transparent material processing applications.

  3. Enhancement of surface properties for coal beneficiation

    Energy Technology Data Exchange (ETDEWEB)

    Chander, S.; Aplan, F.F.

    1992-01-30

    This report will focus on means of pyrite removal from coal using surface-based coal cleaning technologies. The major subjects being addressed in this study are the natural and modulated surface properties of coal and pyrite and how they may best be utilized to facilitate their separation using advanced surface-based coal cleaning technology. Emphasis is based on modified flotation and oil agglomerative processes and the basic principles involved. The four areas being addressed are: (1) Collectorless flotation of pyrite; (2) Modulation of pyrite and coal hydrophobicity; (3) Emulsion processes and principles; (4) Evaluation of coal hydrophobicity.

  4. Evans blue dye-enhanced imaging of the brain microvessels using spectral focusing coherent anti-Stokes Raman scattering microscopy.

    Directory of Open Access Journals (Sweden)

    Bo-Ram Lee

    Full Text Available We performed dye-enhanced imaging of mouse brain microvessels using spectral focusing coherent anti-Stokes Raman scattering (SF-CARS microscopy. The resonant signals from C-H stretching in forward CARS usually show high background intensity in tissues, which makes CARS imaging of microvessels difficult. In this study, epi-detection of back-scattered SF-CARS signals showed a negligible background, but the overall intensity of resonant CARS signals was too low to observe the network of brain microvessels. Therefore, Evans blue (EB dye was used as contrasting agent to enhance the back-scattered SF-CARS signals. Breakdown of brain microvessels by inducing hemorrhage in a mouse was clearly visualized using backward SF-CARS signals, following intravenous injection of EB. The improved visualization of brain microvessels with EB enhanced the sensitivity of SF-CARS, detecting not only the blood vessels themselves but their integrity as well in the brain vasculature.

  5. Enhancing osseointegration using surface-modified titanium implants

    Science.gov (United States)

    Yang, Y.; Oh, N.; Liu, Y.; Chen, W.; Oh, S.; Appleford, M.; Kim, S.; Kim, K.; Park, S.; Bumgardner, J.; Haggard, W.; Ong, J.

    2006-07-01

    Osseointegrated dental implants are used to replace missing teeth. The success of implants is due to osseointegration or the direct contact of the implant surface and bone without a fibrous connective tissue interface. This review discusses the enhancement of osseointegration by means of anodized microporous titanium surfaces, functionally macroporous graded titanium coatings, nanoscale titanium surfaces, and different bioactive factors.

  6. Carbon nanostructured surfaces for enhanced heat transport

    NARCIS (Netherlands)

    Taha, T.J.

    2015-01-01

    The advancement of high performance thermal systems has stimulated interest in methods to improve heat transfer rates. Considerable efforts have been made to increase heat transfer rates by implementing passive convective heat transfer enhancement methods that require no direct consumption of

  7. Compact surface plasmon-enhanced fluorescence biochip

    Czech Academy of Sciences Publication Activity Database

    Toma, K.; Vala, Milan; Adam, Pavel; Homola, Jiří; Knoll, W.; Dostálek, J.

    2013-01-01

    Roč. 21, č. 8 (2013), s. 10121-10132 ISSN 1094-4087 R&D Projects: GA ČR GBP205/12/G118 Institutional support: RVO:67985882 Keywords : Surface plasmons * Diffraction gratings * Biological sensing and sensors Subject RIV: BH - Optics, Masers, Lasers Impact factor: 3.525, year: 2013

  8. Surface magnetic enhancement for coal cleaning

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, J.Y.

    1989-01-01

    The progress achieved during this quarter includes the ten months shelf life study of magnetizing reagent, the effect of cation regulators on minerals and coals, the combination effect of depressant and activator on the adsorption of magnetizing reagent, optimum magnetite size for magnetizing reagent, and the magnetic field strength for separating magnetic enhanced minerals. The work is generally on schedule with the original plan. The Phase I study (a fundamental study) is nearly completed. Selective conditions for adsorbing magnetizing reagent on minerals have been identified. The work for the next quarter will be mainly on the Phase II study. Coal will be selected, procured, characterized, and processed.

  9. Raman and Surface Enhanced Raman of Biological Material

    National Research Council Canada - National Science Library

    Guicheteau, Jason A; Gonser, Kristina; Christesen, Steven Dale

    2004-01-01

    .... Vibrational spectroscopic methods such as Raman and surface enhanced Raman scattering (SERS) provide rapid detailed fingerprint information about the molecular composition of biomaterial in a non-destructive manner...

  10. Enhanced Prediction of Gear Tooth Surface Fatigue Life, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Sentient will develop an enhanced prediction of gear tooth surface fatigue life with rigorous analysis of the tribological phenomena that contribute to pitting...

  11. Preparation of surface enhanced Raman substrate and its characterization

    Science.gov (United States)

    Liu, Y.; Wang, J. Y.; Wang, J. Q.

    2017-10-01

    Surface enhanced Raman spectroscopy (SERS) is a fast, convenient and highly sensitive detection technique, and preparing the good effect and repeatable substrate is the key to realize the trace amount and quantitative detection in the field of food safety detection. In this paper, a surface enhanced Raman substrate based on submicrometer silver particles structure was prepared by chemical deposition method, and characterized its structure and optical properties.

  12. Dependence of metal-enhanced fluorescence on surface roughness

    Science.gov (United States)

    François, Alexandre; Sciacca, Beniamino; Zuber, Agnieszka; Klantsataya, Elizaveta; Monro, Tanya M.

    2014-03-01

    Metal Enhanced Fluorescence (MEF) takes advantage of the coupling between surface plasmons, in either a metallic thin film or metallic nanoparticles, and fluorophores located in proximity of the metal, yielding an increase of the fluorophore emission. While MEF has been widely studied on metallic nanoparticles with the emphasis on creating brighter fluorescent labels, planar surfaces have not benefitted from the same attention. Here we investigate the influence of the surface roughness of a thin metallic film on the fluorescence enhancement. 50nm thick silver films were deposited on glass slides using either thermal evaporation with different evaporation currents or an electroless plating method based on the Tollens reaction to vary the surface roughness. Multiple layers of positively and negatively charged polyelectrolytes were deposited on top of the metallic coating to map out the enhancement factor as function of the gap between the metallic coating and fluorophore molecules covalently bound to the last polyelectrolyte layer. We show that fluorescence is enhanced by the presence of the metallic film, and in particular that the enhancement increases by a factor 3 to 40 for roughness ranging from 3 nm to 8 nm. Although these enhancement factors are modest compared to the enhancement produced by complex metallic nanoparticles or nano-patterned metallic thin films, the thin films used here are capable of supporting a plasmonic wave and offer the possibility of combining different techniques, such as surface plasmon resonance (with its higher refractive index sensitivity compared to localized plasmons) and MEF within a single device.

  13. Coherence between interannual variability of sea level with some surface met-ocean parameters at Cochin, southwest coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Srinivas, K.

    Centre, Cochin - 682 014, Kerala, India [ E-mail: srinivas_kantha@rediffmail.com ; srinivas_kantha@yahoo.co.in ] Received 4 October 2001, revised 14 June 2002 The interannual coherence of some surface met-ocean parameters (viz. SST, air temperature....01354, 0.01968 and 0.01428 dyne/cm 2 , respectively. As the numerical values of the observed wind stress are small, the re- siduals (i.e. anomalies) are still smaller. Further, the seasonal signal component in the cross-shore and along-shore wind stress...

  14. Width-Increased Dual-Pump Enhanced Coherent Anti-Stokes Raman Spectroscopy (WIDECARS)

    Science.gov (United States)

    Tedder, Sarah A.; Danehy, Paul M.; Cutler, Andrew D.

    2010-01-01

    WIDECARS is a dual-pump coherent anti-Stokes Raman Spectroscopy technique that is capable of simultaneously measuring temperature and species mole fractions of N2, O2, H2, C2H4, CO, and CO2. WIDECARS is designed for measurements of all the major species (except water) in supersonic combustion flows fueled with hydrogen and hydrogen/ethylene mixtures. The two lowest rotational energy levels of hydrogen detectable by WIDECARS are H2 S(3) and H2 S(4). The detection of these lines gives the system the capability to measure temperature and species concentrations in regions of the flow containing pure hydrogen fuel at room temperature.

  15. Equalization-enhanced phase noise for 100 Gb/s transmission and beyond with coherent detection.

    Science.gov (United States)

    Lau, Alan Pak Tao; Shen, Thomas Shun Rong; Shieh, William; Ho, Keang-Po

    2010-08-02

    The probability density function and impact of equalizationenhanced phase noise (EEPN) is analytically investigated and simulated for 100 Gb/s coherent systems using electronic dispersion compensation. EEPN impairment induces both phase noise and amplitude noise with the former twice as much as the latter. The effects of transmitter phase noise on EEPN are negligible for links with residual dispersion in excess of 700 ps/nm. Optimal linear equalizer in the presence of EEPN is derived but show only marginal performance improvement, indicating that EEPN is difficult to mitigate using simple DSP techniques. In addition, the effects of EEPN on carrier recovery techniques and corresponding cycle slip probabilities are studied.

  16. In situ surface-enhanced raman spectroelectrochemical analysis system with a hemin modified nanostructured gold surface

    NARCIS (Netherlands)

    Yuan, Tao; Le Thi Ngoc, Loan; van Nieuwkasteele, Jan William; Odijk, Mathieu; van den Berg, Albert; Permentier, Hjalmar; Bischoff, Rainer; Carlen, Edwin

    2015-01-01

    An integrated surface-enhanced Raman scattering (SERS) spectroelectrochemical (SEC) analysis system is presented that combines a small volume microfluidic sample chamber (<100 mu L) with a compact three-electrode configuration for in situ surface-enhanced Raman spectroelectrochemistry. The SEC

  17. In situ surface-enhanced Raman spectroelectrochemical analysis system with a hemin modified nanostructured gold surface

    NARCIS (Netherlands)

    Yuan, Tao; Le Thi Ngoc, Loan; van Nieuwkasteele, Jan; Odijk, Mathieu; van den Berg, Albert; Permentier, Hjalmar; Bischoff, Rainer; Carlen, Edwin T

    2015-01-01

    An integrated surface-enhanced Raman scattering (SERS) spectroelectrochemical (SEC) analysis system is presented that combines a small volume microfluidic sample chamber (<100 μL) with a compact three-electrode configuration for in situ surface-enhanced Raman spectroelectrochemistry. The SEC system

  18. Review of spectral domain-enhanced depth imaging optical coherence tomography of tumors of the retina and retinal pigment epithelium in children and adults

    Directory of Open Access Journals (Sweden)

    Carol L Shields

    2015-01-01

    Full Text Available Background: Spectral domain (SD enhanced depth imaging optical coherence tomography (EDI-OCT is a useful tool for anatomic, cross-sectional imaging of retinal conditions. Aims: The aim was to identify characteristic patterns of retinal and retinal pigment epithelial tumors on EDI-OCT in children and adults. Settings and Design: Retrospective review. Materials and Methods: Analysis of published reports and personal observations using office-based EDI-OCT for adults and portable hand-held SD OCT for infants and children. Results: Using EDI-OCT, retinal tumors such as small retinoblastoma, astrocytic hamartoma, and hemangioblastoma arose abruptly from the retina, immediately adjacent to normal retina. Small exophytic retinoblastoma and retinal hemangioblastoma showed the full-thickness, homogeneous retinal disorganization with surrounding normal retina "draping" over the margins. Retinoblastoma occasionally had intralesional cavities and surrounding subretinal fluid. Hemangioblastoma often had adjacent intraretinal edema and subretinal fluid. Astrocytic hamartoma arose within the nerve fiber layer and sometimes with a "moth-eaten" or cavitary appearance. Retinal pigment epithelial (RPE lesions such as congenital hypertrophy of RPE appeared flat with shadowing, occasional subretinal cleft, and abrupt photoreceptor loss. Congenital simple hamartoma showed an abrupt elevation from the inner retina with crisp, dark posterior shadowing. Combined hamartoma of the retina/RPE showed vitreoretinal traction causing "sawtooth mini-peak" or gently "maxi-peak" folding of the retina. RPE adenoma often produces remote macular edema or epiretinal membrane and the tumor has an irregular, "rugged" surface with deep shadowing. Conclusions: Enhanced depth imaging optical coherence tomography shows characteristic patterns that are suggestive of certain retinal and RPE tumors.

  19. Surface-Enhanced Raman Scattering Physics and Applications

    CERN Document Server

    Kneipp, Katrin; Kneipp, Harald

    2006-01-01

    Almost 30 years after the first reports on surface-enhanced Raman signals, the phenomenon of surface-enhanced Raman scattering (SERS) is now well established. Yet, explaining the enhancement of a spectroscopic signal by fouteen orders of magnitude continues to attract the attention of physicists and chemists alike. And, at the same time and rapidly growing, SERS is becoming a very useful spectroscopic tool with exciting applications in many fields. SERS gained particular interest after single-molecule Raman spectroscopy had been demonstrated. This bookl summarizes and discusses present theoretical approaches that explain the phenomenon of SERS and reports on new and exciting experiments and applications of the fascinating spectroscopic effect.

  20. Enhanced crystal-field splitting and orbital-selective coherence induced by strong correlations in V2O3

    Science.gov (United States)

    Poteryaev, Alexander I.; Tomczak, Jan M.; Biermann, Silke; Georges, Antoine; Lichtenstein, Alexander I.; Rubtsov, Alexey N.; Saha-Dasgupta, Tanusri; Andersen, Ole K.

    2007-08-01

    We present a study of the paramagnetic metallic and insulating phases of vanadium sesquioxide by means of the Nth order muffin-tin orbital implementation of density functional theory combined with dynamical mean-field theory. The transition is shown to be driven by a correlation-induced enhancement of the crystal-field splitting within the t2g manifold, which results in a suppression of the hybridization between the a1g and egπ bands. We discuss the changes in the effective quasiparticle band structure caused by the correlations and the corresponding self-energies. At temperatures of about 400K , we find the a1g orbital displays coherent quasiparticle behavior, while a large imaginary part of the self-energy and broad features in the spectral function indicate that the egπ orbitals are still far above their coherence temperature. The local spectral functions are in excellent agreement with recent bulk sensitive photoemission data. Finally, we also make a prediction for angle-resolved photoemission experiments by calculating momentum-resolved spectral functions.

  1. A comparison of two methods to measure choroidal thickness by enhanced depth imaging optical coherence tomography

    DEFF Research Database (Denmark)

    Lundberg, Lars Kristian; Vestergaard, Anders Højslet; Vergmann, Anna Stage

    for mean intergrader ICC were 0.97 ±0.027 and 0.95 ±0.03 (P=0.17). A shorter mean time was found for the Segmentation method (7.3 ±1.6 minutes vs. 9.0 ±1.8 minutes, Pmethods from the inbuilt Heidelberg Eye Explorer software were suitable for manual measurement of the CT and showed...... coherence tomography (EDI-SD OCT) has made it possible to visualize the choroid, and it is generally accepted that Heidelberg Spectralis OCT provides valid measurements of choroidal thickness (CT), although no fully automated software is commercially available. Two methods for CT-measurement are available...... in the Heidelberg software, but to our knowledge these have not been compared. Hence, the purpose of this study was to evaluate and validate the Segmentation method and the Ruler method for CT-measurement. Methods We used the Heidelberg Spectralis (Heidelberg Engineering, Heidelberg, Germany) to record EDI...

  2. Emerging enhanced imaging technologies of the esophagus: spectroscopy, confocal laser endomicroscopy, and optical coherence tomography.

    Science.gov (United States)

    Robles, Lourdes Y; Singh, Satish; Fisichella, Piero Marco

    2015-05-15

    Despite advances in diagnoses and therapy, esophageal adenocarcinoma remains a highly lethal neoplasm. Hence, a great interest has been placed in detecting early lesions and in the detection of Barrett esophagus (BE). Advanced imaging technologies of the esophagus have then been developed with the aim of improving biopsy sensitivity and detection of preplastic and neoplastic cells. The purpose of this article was to review emerging imaging technologies for esophageal pathology, spectroscopy, confocal laser endomicroscopy (CLE), and optical coherence tomography (OCT). We conducted a PubMed search using the search string "esophagus or esophageal or oesophageal or oesophagus" and "Barrett or esophageal neoplasm" and "spectroscopy or optical spectroscopy" and "confocal laser endomicroscopy" and "confocal microscopy" and "optical coherence tomography." The first and senior author separately reviewed all articles. Our search identified: 19 in vivo studies with spectroscopy that accounted for 1021 patients and 4 ex vivo studies; 14 clinical CLE in vivo studies that accounted for 941 patients and 1 ex vivo study with 13 patients; and 17 clinical OCT in vivo studies that accounted for 773 patients and 2 ex vivo studies. Human studies using spectroscopy had a very high sensitivity and specificity for the detection of BE. CLE showed a high interobserver agreement in diagnosing esophageal pathology and an accuracy of predicting neoplasia. We also found several clinical studies that reported excellent diagnostic sensitivity and specificity for the detection of BE using OCT. Advanced imaging technology for the detection of esophageal lesions is a promising field that aims to improve the detection of early esophageal lesions. Although advancing imaging techniques improve diagnostic sensitivities and specificities, their integration into diagnostic protocols has yet to be perfected. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Exploring the chemical enhancement for surface-enhanced Raman scattering with Au bowtie nanoantennas

    International Nuclear Information System (INIS)

    Fromm, David P.; Sundaramurthy, Arvind; Kinkhabwala, Anika; Schuck, P. James; Kino, Gordon S.; Moerner, W.E.

    2006-01-01

    Single metallic bowtie nanoantennas provide a controllable environment for surface-enhanced Raman scattering (SERS) of adsorbed molecules. Bowties have experimentally measured electromagnetic enhancements, enabling estimation of chemical enhancement for both the bulk and the few-molecule regime. Strong fluctuations of selected Raman lines imply that a small number of p-mercaptoaniline molecules on a single bowtie show chemical enhancement >10 7 , much larger than previously believed, likely due to charge transfer between the Au surface and the molecule. This chemical sensitivity of SERS has significant implications for ultra-sensitive detection of single molecules

  4. Enhanced-Depth Imaging Optical Coherence Tomography of the Human Choroid In Vivo Compared With Histology After Enucleation

    DEFF Research Database (Denmark)

    Li, Xiao Qiang; Heegaard, Steffen; Kiilgaard, Jens Folke

    2016-01-01

    PURPOSE: This study compared in vivo enhanced-depth imaging optical coherence tomography (EDI-OCT) with ex vivo histology of the choroid in human eyes. METHODS: Three eyes in three patients with advanced iris melanoma without posterior segment involvement underwent EDI-OCT less than 24 hours prior...... such as retinal vessel, the foveal depression, ciliary arteries, drusen, and nevi. RESULTS: Intra- and interindividual variations in relative choroidal thickness were comparable between the two modalities. After histologic fixation of the three melanoma eyes, the fullness of the choroidal vessels was reduced...... to enucleation and, in one eye, immediately after enucleation. Following fixation in 4% buffered formaldehyde and paraffin embedding, serial sections of the whole eye were cut horizontally, mounted, stained with hematoxylin-eosin and digitized. Alignment between histology and EDI-OCT was made on landmarks...

  5. Quantitatively Measured Anatomic Location and Volume of Optic Disc Drusen: An Enhanced Depth Imaging Optical Coherence Tomography Study

    DEFF Research Database (Denmark)

    Malmqvist, Lasse; Lindberg, Anne-Sofie Wessel; Dahl, Vedrana Andersen

    2017-01-01

    Optic disc drusen (ODD) are found in up to 2.4% of the population and are known to cause visual field defects. The purpose of the current study was to investigate how quantitatively estimated volume and anatomic location of ODD influence optic nerve function. Anatomic location, volume of ODD......, and peripapillary retinal nerve fiber layer and macular ganglion cell layer thickness were assessed in 37 ODD patients using enhanced depth imaging optical coherence tomography. Volume of ODD was calculated by manual segmentation of ODD in 97 B-scans per eye. Anatomic characteristics were compared with optic nerve.......025) and had a higher effect on MD when compared to retinal nerve fiber layer thickness. Large ODD volume is associated with optic nerve dysfunction. The worse visual field defects associated with visible ODD should only be ascribed to larger ODD volume and not to a more superficial anatomic ODD location....

  6. Nondestructive surface profiling of hidden MEMS using an infrared low-coherence interferometric microscope

    Science.gov (United States)

    Krauter, Johann; Osten, Wolfgang

    2018-03-01

    There are a wide range of applications for micro-electro-mechanical systems (MEMS). The automotive and consumer market is the strongest driver for the growing MEMS industry. A 100 % test of MEMS is particularly necessary since these are often used for safety-related purposes such as the ESP (Electronic Stability Program) system. The production of MEMS is a fully automated process that generates 90 % of the costs during the packaging and dicing steps. Nowadays, an electrical test is carried out on each individual MEMS component before these steps. However, after encapsulation, MEMS are opaque to visible light and other defects cannot be detected. Therefore, we apply an infrared low-coherence interferometer for the topography measurement of those hidden structures. A lock-in algorithm-based method is shown to calculate the object height and to reduce ghost steps due to the 2π -unambiguity. Finally, measurements of different MEMS-based sensors are presented.

  7. Raman and surface enhanced Raman spectroscopic investigation on Lamiaceae plants

    Science.gov (United States)

    Rösch, P.; Popp, J.; Kiefer, W.

    1999-05-01

    The essential oils of Thymus vulgaris and Origanum vulgaris are studied by means of micro-Raman spectroscopy. The containing monoterpenes can be identified by their Raman spectra. Further the essential oils are investigated in their natural environment, the so-called oil cells of these Lamiaceae plants, with surface enhanced Raman spectroscopy (SERS). This method has the advantage to enhance Raman signals and furthermore the SERS effect leads to fluorescence quenching.

  8. Enhanced adhesion of bioinspired nanopatterned elastomers via colloidal surface assembly

    Science.gov (United States)

    Akerboom, Sabine; Appel, Jeroen; Labonte, David; Federle, Walter; Sprakel, Joris; Kamperman, Marleen

    2015-01-01

    We describe a scalable method to fabricate nanopatterned bioinspired dry adhesives using colloidal lithography. Close-packed monolayers of polystyrene particles were formed at the air/water interface, on which polydimethylsiloxane (PDMS) was applied. The order of the colloidal monolayer and the immersion depth of the particles were tuned by altering the pH and ionic strength of the water. Initially, PDMS completely wetted the air/water interface outside the monolayer, thereby compressing the monolayer as in a Langmuir trough; further application of PDMS subsequently covered the colloidal monolayers. PDMS curing and particle extraction resulted in elastomers patterned with nanodimples. Adhesion and friction of these nanopatterned surfaces with varying dimple depth were studied using a spherical probe as a counter-surface. Compared with smooth surfaces, adhesion of nanopatterned surfaces was enhanced, which is attributed to an energy-dissipating mechanism during pull-off. All nanopatterned surfaces showed a significant decrease in friction compared with smooth surfaces. PMID:25392404

  9. New aspects of electronic excitations at the bismuth surface: Topology, thermalization and coupling to coherent phonons

    Energy Technology Data Exchange (ETDEWEB)

    Perfetti, L., E-mail: luca.perfetti@polytechnique.edu [Laboratoire des Solides Irradiés, Ecole Polytechnique – CEA/DSM – CNRS UMR 7642, 91128 Palaiseau (France); Faure, J. [Laboratoire d’Optique Appliquée, Ecole Polytechnique – ENSTA – CNRS UMR 7639, 91761 Palaiseau (France); Papalazarou, E.; Mauchain, J.; Marsi, M.; Goerbig, M.O. [Laboratoire de Physique des Solides, CNRS UMR 8502, Université Paris-Sud, F-91405 Orsay (France); Taleb-Ibrahimi, A.; Ohtsubo, Y. [Synchrotron SOLEIL, Saint-Aubin-BP 48, F-91192 Gif sur Yvette (France)

    2015-05-15

    We review measurements of angle and time resolved photoelectron spectroscopy on the surface states of the Bi(1 1 1) surface. The work covers several aspects of these surface states, discussing the topological properties, the strong anisotropy of the spin–orbit splitting and the dynamical relaxation of photoexcited electrons. Since time resolved experiments disentagle interaction processes in real time, the reported data offer a novel perspective on the motion of charge carriers in surface states and will serve as an unuseful reference for other systems with strong spin–orbit coupling.

  10. Coherent Surface Clutter Suppression Techniques with Topography Estimation for Multi-Phase-Center Radar Ice Sounding

    DEFF Research Database (Denmark)

    Nielsen, Ulrik; Dall, Jørgen; Kristensen, Steen Savstrup

    2012-01-01

    Radar ice sounding enables measurement of the thickness and internal structures of the large ice sheets on Earth. Surface clutter masking the signal of interest is a major obstacle in ice sounding. Algorithms for surface clutter suppression based on multi-phase-center radars are presented...

  11. Coherent Surface Clutter Suppression Techniques with Topography Estimation for Multi-Phase-Center Radar Ice Sounding

    DEFF Research Database (Denmark)

    Nielsen, Ulrik; Dall, Jørgen; Kristensen, Steen Savstrup

    2012-01-01

    Radar ice sounding enables measurement of the thickness and internal structures of the large ice sheets on Earth. Surface clutter masking the signal of interest is a major obstacle in ice sounding. Algorithms for surface clutter suppression based on multi-phase-center radars are presented. These ...

  12. Resonance surface enhanced Raman optical activity of myoglobin as a result of optimized resonance surface enhanced Raman scattering conditions

    DEFF Research Database (Denmark)

    Abdali, Salim; Johannessen, Christian; Nygaard, Jesper

    2007-01-01

    Using Surface enhanced ROA (SEROA), novel results are achieved by combining Raman Optical Activity (ROA) and resonance Surface Enhanced Raman Scattering (SERRS), applied on myoglobin. The novelty of this work is ascribed the first time reporting on chiral results of a study performed on a protein...... has shown that the SERS effect behaves consequently, depending on the concentration ratio of each component, i.e., myoglobin, Ag colloids and NaCl. Accordingly, it is shown here that SERS intensity has its maximum at certain concentration of these components, whereas below or above this value...

  13. Implications of surface noise for the motional coherence of trapped ions

    Science.gov (United States)

    Talukdar, I.; Gorman, D. J.; Daniilidis, N.; Schindler, P.; Ebadi, S.; Kaufmann, H.; Zhang, T.; Häffner, H.

    2016-04-01

    Electric noise from metallic surfaces is a major obstacle towards quantum applications with trapped ions due to motional heating of the ions. Here, we discuss how the same noise source can also lead to pure dephasing of motional quantum states. The mechanism is particularly relevant at small ion-surface distances, thus imposing a constraint on trap miniaturization. By means of a free induction decay experiment, we measure the dephasing time of the motion of a single ion trapped 50 μ m above a Cu-Al surface. From the dephasing times we extract the integrated noise below the secular frequency of the ion. We find that none of the most commonly discussed surface noise models for ion traps describes both the observed heating as well as the measured dephasing satisfactorily. Thus, our measurements provide a benchmark for future models for the electric noise emitted by metallic surfaces.

  14. Accessible coherence and coherence distribution

    Science.gov (United States)

    Ma, Teng; Zhao, Ming-Jing; Zhang, Hai-Jun; Fei, Shao-Ming; Long, Gui-Lu

    2017-04-01

    The definition of accessible coherence is proposed. Through local measurement on the other subsystem and one-way classical communication, a subsystem can access more coherence than the coherence of its density matrix. Based on the local accessible coherence, the part that cannot be locally accessed is also studied, which we call it remaining coherence. We study how the bipartite coherence is distributed by partition for both l1 norm coherence and relative entropy coherence, and the expressions for local accessible coherence and remaining coherence are derived. We also study some examples to illustrate the distribution.

  15. Metal-coated magnetic nanoparticles for surface enhanced Raman ...

    Indian Academy of Sciences (India)

    magnetic properties of these nanoparticles combined with SERS provide a wide range of applications. Keywords. Surface-enhanced Raman scattering; magnetic nanoparticles; core-shell nanostructure; bio-diagnosis. 1. Introduction. In recent years, plasmonic nanostructures exhibiting novel optical properties have attracted ...

  16. Metal-coated magnetic nanoparticles for surface enhanced Raman ...

    Indian Academy of Sciences (India)

    We report the optimization and usage of surfactantless, water dispersible Ag and Au-coated γ–Fe2O3 nanoparticles for applications in surface-enhanced .... After the solvent evaporated, 2 μL of analyte of ∼1 μM concentration was ..... dry soil, and comprised of smooth, distinct, rectangular and square shaped islands, whose ...

  17. Surface enhanced Raman spectra of the organic nonlinear optic ...

    Indian Academy of Sciences (India)

    Wintec

    Institute of Chemistry, University of Opole, Olesksa 48 45-052 Opole, Poland. 1. Present Address: Department of Physics, V.P.S.H.S.S. for ... co-ordination chemistry. Surface-enhanced Raman scattering (SERS), using .... numbers were calculated using analytic second de- rivatives to confirm the convergence to minima on.

  18. Surface Reconstruction and Image Enhancement via $L^1$-Minimization

    KAUST Repository

    Dobrev, Veselin

    2010-01-01

    A surface reconstruction technique based on minimization of the total variation of the gradient is introduced. Convergence of the method is established, and an interior-point algorithm solving the associated linear programming problem is introduced. The reconstruction algorithm is illustrated on various test cases including natural and urban terrain data, and enhancement oflow-resolution or aliased images. Copyright © by SIAM.

  19. Near-Ir surface-enhanced Raman spectrum of lignin

    Science.gov (United States)

    Umesh P. Agarwal; Richard S. Reiner

    2009-01-01

    Compacted powders of commercially available nano- and microparticles of silver were used to successfully induce the surface enhanced Raman scattering (SERS) effect in spruce milled-wood lignin (MWL). For the two silver particle sizes used in this investigation, the spectra were mostly similar. Some general characteristics of the lignin SERS spectrum are described. The...

  20. Asphaltene detection using surface enhanced Raman scattering (SERS).

    Science.gov (United States)

    Alabi, O O; Edilbi, A N F; Brolly, C; Muirhead, D; Parnell, J; Stacey, R; Bowden, S A

    2015-04-28

    Surface enhanced Raman spectroscopy using a gold substrate and excitation at 514 nm can detect sub parts per million quantities of asphaltene and thereby petroleum. This simple format and sensitivity make it transformative for applications including sample triage, flow assurance, environmental protection and analysis of unique one of a kind materials.

  1. Surface-enhanced Raman spectroscopy of DNA bases

    NARCIS (Netherlands)

    Otto, Cornelis; van den Tweel, T.J.J.; de Mul, F.F.M.; Greve, Jan

    1986-01-01

    A Raman microprobe has been used to measure the surface-enhanced Raman spectra of adenine, guanine, cytosine and thymine. Comparison of the SERS spectrum with solution spectra shows that some line positions are not influenced by the adsorption process while others show large shifts. In the SERS

  2. Jumping-droplet-enhanced condensation on scalable superhydrophobic nanostructured surfaces.

    Science.gov (United States)

    Miljkovic, Nenad; Enright, Ryan; Nam, Youngsuk; Lopez, Ken; Dou, Nicholas; Sack, Jean; Wang, Evelyn N

    2013-01-09

    When droplets coalesce on a superhydrophobic nanostructured surface, the resulting droplet can jump from the surface due to the release of excess surface energy. If designed properly, these superhydrophobic nanostructured surfaces can not only allow for easy droplet removal at micrometric length scales during condensation but also promise to enhance heat transfer performance. However, the rationale for the design of an ideal nanostructured surface as well as heat transfer experiments demonstrating the advantage of this jumping behavior are lacking. Here, we show that silanized copper oxide surfaces created via a simple fabrication method can achieve highly efficient jumping-droplet condensation heat transfer. We experimentally demonstrated a 25% higher overall heat flux and 30% higher condensation heat transfer coefficient compared to state-of-the-art hydrophobic condensing surfaces at low supersaturations (heat transfer enhancement but also promises a low cost and scalable approach to increase efficiency for applications such as atmospheric water harvesting and dehumidification. Furthermore, the results offer insights and an avenue to achieve high flux superhydrophobic condensation.

  3. Ultrasound enhanced plasma surface modification at atmospheric pressure

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Singh, Shailendra Vikram; Norrman, Kion

    2012-01-01

    Efficiency of atmospheric pressure plasma treatment can be highly enhanced by simultaneous high power ultrasonic irradiation onto the treating surface. It is because ultrasonic waves with a sound pressure level (SPL) above ∼140 dB can reduce the thickness of a boundary gas layer between the plasma...... arc at atmospheric pressure to study adhesion improvement. The effect of ultrasonic irradiation with the frequency diapason between 20 and 40 kHz at the SPL of ∼150 dB was investigated. After the plasma treatment without ultrasonic irradiation, the wettability was significantly improved....... The ultrasonic irradiation during the plasma treatment consistently enhanced the treatment efficiency. The principal effect of ultrasonic irradiation can be attributed to enhancing surface oxidation during plasma treatment. In addition, ultrasonic irradiation can suppress arcing, and the uniformity...

  4. Latent fingerprint wavelet transform image enhancement technique for optical coherence tomography

    CSIR Research Space (South Africa)

    Makinana, S

    2016-09-01

    Full Text Available like DNA. Being able to acquire latent fingerprints without physical contact with the surface could be advantageous. These advantages are as follows; being able to acquire the imprint multiple times, there is no physical or chemical processing of a...

  5. Directional surface enhanced Raman scattering on gold nano-gratings

    International Nuclear Information System (INIS)

    Gillibert, Raymond; Yasukuni, Ryohei; Chapelle, Marc Lamy de la; Sarkar, Mitradeep; Bryche, Jean-François; Moreau, Julien; Besbes, Mondher; Canva, Michael; Barbillon, Grégory; Bartenlian, Bernard

    2016-01-01

    Directional plasmon excitation and surface enhanced Raman scattering (SERS) emission were demonstrated for 1D and 2D gold nanostructure arrays deposited on a flat gold layer. The extinction spectrum of both arrays exhibits intense resonance bands that are redshifted when the incident angle is increased. Systematic extinction analysis of different grating periods revealed that this band can be assigned to a propagated surface plasmon of the flat gold surface that fulfills the Bragg condition of the arrays (Bragg mode). Directional SERS measurements demonstrated that the SERS intensity can be improved by one order of magnitude when the Bragg mode positions are matched with either the excitation or the Raman wavelengths. Hybridized numerical calculations with the finite element method and Fourier modal method also proved the presence of the Bragg mode plasmon and illustrated that the enhanced electric field of the Bragg mode is particularly localized on the nanostructures regardless of their size. (paper)

  6. Enhanced Bioactivity and Bacteriostasis of Surface Fluorinated Polyetheretherketone.

    Science.gov (United States)

    Chen, Meiling; Ouyang, Liping; Lu, Tao; Wang, Heying; Meng, Fanhao; Yang, Yan; Ning, Congqin; Ma, Jingzhi; Liu, Xuanyong

    2017-05-24

    Although polyetheretherketone (PEEK) has been considered as a potential orthopedic and dental application material due to its similar elastic modulus as bones, inferior osseointegration and bacteriostasis of PEEK hampers its clinical application. In this work, fluorinated PEEK was constructed via plasma immersion ion implantation (PIII) followed by hydrofluoric acid treatment to ameliorate the osseointegration and antibacterial properties of PEEK. The surface microstructure, composition, and hydrophilicity of all samples were investigated. Rat bone mesenchymal stem cells (rBMSCs) were cultured on their surfaces to estimate bioactivity. The fluorinated PEEK can enhance the cell adhesion, cell spreading, proliferation, and alkaline phosphatase (ALP) activity compared to pristine PEEK. Furthermore, the fluorinated PEEK surface exhibits good bacteriostatic effect against Porphyromonas gingivalis, which is one of the major periodontal pathogens. In summary, we provide an effective route to introduce fluorine and the results reveal that the fluorinated PEEK can enhance the osseointegration and bacteriostasis, which provides a potential candidate for dental implants.

  7. Feasibility of correlation mapping optical coherence tomography (cmOCT) for anti-spoof sub-surface fingerprinting.

    Science.gov (United States)

    Zam, Azhar; Dsouza, Roshan; Subhash, Hrebesh M; O'Connell, Marie-Louise; Enfield, Joey; Larin, Kirill; Leahy, Martin J

    2013-09-01

    We propose the use of correlation mapping optical coherence tomography (cmOCT) to deliver additional biometrics associated with the finger that could complement existing fingerprint technology for law enforcement applications. The current study extends the existing fingerprint paradigm by measuring additional biometrics associated with sub-surface finger tissue such as sub-surface fingerprints, sweat glands, and the pattern of the capillary bed to yield a user-friendly cost effective and anti-spoof multi-mode biometric solution associated with the finger. To our knowledge no other method has been able to capture sub-surface fingerprint, papillary pattern and horizontal vessel pattern in a single scan or to show the correspondence between these patterns in live adult human fingertip. Unlike many current technologies this approach incorporates 'liveness' testing by default. The ultimate output is a biometric module which is difficult to defeat and complements fingerprint scanners that currently are used in border control and law enforcement applications. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Surface-enhanced Raman scattering on gold nanotrenches and nanoholes

    KAUST Repository

    Yue, Weisheng

    2012-04-01

    Dependent effects on edge-to-edge distance and incidence polarization in surface-enhanced Raman Scattering (SERS) were studied in detection of 4-mercaptopyridine (4-MPy) molecules absorbed on gold nanotrenches and nanoholes. The gold nanostructures with controllable size and period were fabricated using electron-beam lithography. Large SERS enhancement in detection of 4-MPy molecules on both nanostructred substrates was observed. The SERS enhancement increased exponentially with decrease of edge to-edge distance for both the nanotrenches and nanoholes while keeping the sizes of the nanotrenches and nanoholes unchanged. Investigation of polarization dependence showed that the SERS enhancement of nanotrenches was much more sensitive to the incidence polarizations than that of nanoholes. © 2012 American Scientific Publishers.

  9. A Simplified Method to Measure Choroidal Thickness Using Adaptive Compensation in Enhanced Depth Imaging Optical Coherence Tomography

    Science.gov (United States)

    Gupta, Preeti; Sidhartha, Elizabeth; Girard, Michael J. A.; Mari, Jean Martial; Wong, Tien-Yin; Cheng, Ching-Yu

    2014-01-01

    Purpose To evaluate a simplified method to measure choroidal thickness (CT) using commercially available enhanced depth imaging (EDI) spectral domain optical coherence tomography (SD-OCT). Methods We measured CT in 31 subjects without ocular diseases using Spectralis EDI SD-OCT. The choroid-scleral interface of the acquired images was first enhanced using a post-processing compensation algorithm. The enhanced images were then analysed using Photoshop. Two graders independently graded the images to assess inter-grader reliability. One grader re-graded the images after 2 weeks to determine intra-grader reliability. Statistical analysis was performed using intra-class correlation coefficient (ICC) and Bland-Altman plot analyses. Results Using adaptive compensation both the intra-grader reliability (ICC: 0.95 to 0.97) and inter-grader reliability (ICC: 0.93 to 0.97) were perfect for all five locations of CT. However, with the conventional technique of manual CT measurements using built-in callipers provided with the Heidelberg explorer software, the intra- (ICC: 0.87 to 0.94) and inter-grader reliability (ICC: 0.90 to 0.93) for all the measured locations is lower. Using adaptive compensation, the mean differences (95% limits of agreement) for intra- and inter-grader sub-foveal CT measurements were −1.3 (−3.33 to 30.8) µm and −1.2 (−36.6 to 34.2) µm, respectively. Conclusions The measurement of CT obtained from EDI SD-OCT using our simplified method was highly reliable and efficient. Our method is an easy and practical approach to improve the quality of choroidal images and the precision of CT measurement. PMID:24797674

  10. A simplified method to measure choroidal thickness using adaptive compensation in enhanced depth imaging optical coherence tomography.

    Directory of Open Access Journals (Sweden)

    Preeti Gupta

    Full Text Available PURPOSE: To evaluate a simplified method to measure choroidal thickness (CT using commercially available enhanced depth imaging (EDI spectral domain optical coherence tomography (SD-OCT. METHODS: We measured CT in 31 subjects without ocular diseases using Spectralis EDI SD-OCT. The choroid-scleral interface of the acquired images was first enhanced using a post-processing compensation algorithm. The enhanced images were then analysed using Photoshop. Two graders independently graded the images to assess inter-grader reliability. One grader re-graded the images after 2 weeks to determine intra-grader reliability. Statistical analysis was performed using intra-class correlation coefficient (ICC and Bland-Altman plot analyses. RESULTS: Using adaptive compensation both the intra-grader reliability (ICC: 0.95 to 0.97 and inter-grader reliability (ICC: 0.93 to 0.97 were perfect for all five locations of CT. However, with the conventional technique of manual CT measurements using built-in callipers provided with the Heidelberg explorer software, the intra- (ICC: 0.87 to 0.94 and inter-grader reliability (ICC: 0.90 to 0.93 for all the measured locations is lower. Using adaptive compensation, the mean differences (95% limits of agreement for intra- and inter-grader sub-foveal CT measurements were -1.3 (-3.33 to 30.8 µm and -1.2 (-36.6 to 34.2 µm, respectively. CONCLUSIONS: The measurement of CT obtained from EDI SD-OCT using our simplified method was highly reliable and efficient. Our method is an easy and practical approach to improve the quality of choroidal images and the precision of CT measurement.

  11. Dimensional scale effects on surface enhanced Raman scattering efficiency of self-assembled silver nanoparticle clusters

    Energy Technology Data Exchange (ETDEWEB)

    Fasolato, C. [Dip. Fisica, Università Sapienza, P.le Aldo Moro, 5, 00185 Rome (Italy); Center for Life Nanoscience@Sapienza, Istituto Italiano di Tecnologia, V.le Regina Elena, 291, 00185 Rome (Italy); Domenici, F., E-mail: fabiodomenici@gmail.com, E-mail: paolo.postorino@roma1.infn.it; De Angelis, L.; Luongo, F.; Postorino, P., E-mail: fabiodomenici@gmail.com, E-mail: paolo.postorino@roma1.infn.it [Dip. Fisica, Università Sapienza, P.le Aldo Moro, 5, 00185 Rome (Italy); Sennato, S. [Dip. Fisica, Università Sapienza, P.le Aldo Moro, 5, 00185 Rome (Italy); CNR-IPCS UOS Roma, Dip. Fisica, Università Sapienza, P.le Aldo Moro, 5, 00185 Rome (Italy); Mura, F. [Dip. Scienze di Base Applicate all' Ingegneria, Università Sapienza, Via A. Scarpa, 16, 00185 Rome (Italy); Costantini, F. [Dip. Ingegneria Astronautica Elettrica ed Energetica, Università Sapienza, Via Eudossiana, 18, 00184 Rome (Italy); Bordi, F. [Dip. Fisica, Università Sapienza, P.le Aldo Moro, 5, 00185 Rome (Italy); Center for Life Nanoscience@Sapienza, Istituto Italiano di Tecnologia, V.le Regina Elena, 291, 00185 Rome (Italy); CNR-IPCS UOS Roma, Dip. Fisica, Università Sapienza, P.le Aldo Moro, 5, 00185 Rome (Italy)

    2014-08-18

    A study of the Surface Enhanced Raman Scattering (SERS) from micrometric metallic nanoparticle aggregates is presented. The sample is obtained from the self-assembly on glass slides of micro-clusters of silver nanoparticles (60 and 100 nm diameter), functionalized with the organic molecule 4-aminothiophenol in water solution. For nanoparticle clusters at the micron scale, a maximum enhancement factor of 10{sup 9} is estimated from the SERS over the Raman intensity ratio normalized to the single molecule contribution. Atomic force microscopy, correlated to spatially resolved Raman measurements, allows highlighting the connection between morphology and efficiency of the plasmonic system. The correlation between geometric features and SERS response of the metallic structures reveals a linear trend of the cluster maximum scattered intensity as a function of the surface area of the aggregate. On given clusters, the intensity turns out to be also influenced by the number of stacking planes of the aggregate, thus suggesting a plasmonic waveguide effect. The linear dependence results weakened for the largest area clusters, suggesting 30 μm{sup 2} as the upper limit for exploiting the coherence over large scale of the plasmonic response.

  12. Validation of swept source optical coherence tomography (SS-OCT) for the diagnosis of smooth surface caries in vitro.

    Science.gov (United States)

    Nakagawa, Hisaichi; Sadr, Alireza; Shimada, Yasushi; Tagami, Junji; Sumi, Yasunori

    2013-01-01

    An accurate evaluation of the extent of dental caries and possible progress of the lesion from enamel into dentin is very important in clinical dentistry. Dentists need an imaging technology that can noninvasively and reliably quantify the extent of caries. This study aimed to evaluate the effectiveness of non-polarized swept source optical coherence tomography (OCT) in evaluating the extent of caries on smooth enamel surfaces. One-hundred and twenty-seven investigation sites on the enamel surfaces of 93 extracted teeth were selected randomly and examined visually. The presence and extent of caries were scored by experienced and inexperienced dentists using each observation method (0: no caries; 1: enamel demineralization without surface breakdown; 2: enamel breakdown due to caries; 3: deep caries involving the dentin). The same locations were then examined using OCT, following which the teeth were sectioned using a diamond saw and viewed directly under a confocal laser scanning microscope (CLSM). Sensitivity and specificity indices for OCT and VI were calculated and compared. The results were analysed statistically using receiver operating characteristic (ROC) curves. Enamel and dentin caries were outlined by a visible boundary on the cross-sectional OCT images. The modality showed superior results for the detection of dentinal caries; higher sensitivity and Az values could be obtained in the ROC curves, especially by experienced dentists. Cross-sectional imaging of the natural caries lesions on smooth enamel surface by OCT enables efficient diagnosis of the lesion type, extent and dentin involvement. SS-OCT can demonstrate the cross-sectional image of smooth surface enamel caries as highlighted zone in tomogram. It is crucial to determine the extent of the lesion, whether it reaches beyond DEJ or not by a non-invasive and safe technique. OCT can give clinicians information about internal tooth structure and will help clinical decision making on surgical

  13. Part I. Quantum Manifestations of Classical Chaos in the Kicked Harper Model. Part II. Coherent Backscattering of a Scalar Wave off a Rough Surface.

    Science.gov (United States)

    D'Souza, Mark

    1995-01-01

    Part I: Quantum manifestations of classical chaos in the Kicked Harper model. The Kicked Harper model has been used to study the quantum manifestations of classical chaos. The variation of a single parameter results in a transition of the classical system from nearly-integrable to chaotic. A second parameter controls the transition between classical and quantum behavior. In the semiclassical limit Bohr's Correspondence Principle predicts the quantum and classical results should match. The quantum system is studied using a tight-binding form of the Hamiltonian, and its time-evolution is studied using minimal uncertainty Gaussian wave packets. The aim is to study the evolution of the quantum system when the classical system is chaotic. Results show the correspondence principle works well when the classical system is not chaotic, but quickly breaks down for chaotic classical motion. In addition, the quasi-energy levels of the Floquet matrix are calculated. When the classical system undergoes a transition from nearly-integrable to chaotic, the quasi-energy levels are expected to exhibit level repulsion. In this case, the level-spacing distribution is expected to undergo a transition from being Poisson -like, to Wigner-like. Results verify that this transition takes place. The introduction of an additional symmetry into the Hamiltonian is seen to change the level repulsion and level-spacing distribution. Part II: Coherent backscattering of a scalar wave off a rough surface. Coherent backscattering is the enhancement of scattering in the backward direction caused by scattering off a random scattering medium or a rough surface. The mechanism responsible is the interference of time-reversed paths during multiple-scattering. Scattering off a rough surface is studied using a one-dimensional lattice of scattering centers, displaced from the perfect lattice positions to introduce randomness. The scattering intensity is obtained in the form of a power series which includes all

  14. Ionic enhancement of silica surface nanowear in electrolyte solutions

    KAUST Repository

    Vakarelski, Ivan Uriev

    2012-11-20

    The nanoscale wear and friction of silica and silicon nitride surfaces in aqueous electrolyte solutions were investigated by using sharp atomic force microscope (AFM) cantilever tips coated with silicon nitride. Measurements were carried out in aqueous solutions of varying pH and in monovalent and divalent cation chloride and nitrate solutions. The silica surface was shown to wear strongly in solutions of high pH (≈11.0), as expected, but the presence of simple cations, such as Cs+ and Ca2+, was shown to dramatically effect the wear depth and friction force for the silica surface. In the case of monovalent cations, their hydration enthalpies correlated well with the wear and friction. The weakest hydrated cation of Cs+ showed the most significant enhancement of wear and friction. In the case of divalent cations, a complex dependence on the type of cation was found, where the type of anion was also seen to play an important role. The CaCl2 solution showed the anomalous enhancement of wear depth and friction force, although the solution of Ca(NO3)2 did not. The present results obtained with an AFM tip were also compared with previous nanotribology studies of silica surfaces in electrolyte solutions, and possible molecular mechanisms as to why cations enhance the wear and friction were also discussed. © 2012 American Chemical Society.

  15. Ultrasound enhanced plasma surface modification at atmospheric pressure

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Singh, Shailendra Vikram; Norrman, Kion

    irradiation, the water contact angle dropped markedly, and tended to decrease furthermore at higher power. The ultrasonic irradiation during the plasma treatment consistently improved the wettability. Oxygen containing polar functional groups were introduced at the surface by the plasma treatment......Atmospheric pressure plasma treatment can be highly enhanced by simultaneous high-power ultrasonic irradiation onto the treating surface. It is because ultrasonic waves with a sound pressure level (SPL) above approximately 140 dB can reduce the thickness of a boundary gas layer between the plasma...... are separated using a polyethylene film. The gliding arc was extended by a high speed air flow into ambient air, directed the polyester surface at an angle of approximately 30o. The ultrasonic waves were introduced vertically to the surface. After the plasma treatment using each plasma source without ultrasonic...

  16. In vivo retinal optical coherence tomography at 1030 nm with enhanced penetration into the choroid

    Science.gov (United States)

    Unterhuber, A.; Povazay, B.; Hermann, B.; Sattmann, H.; Michels, S.; Sacu, S.; Ahlers, C.; Scholda, C.; Chavez-Pirson, A.; Schmidt-Erfurth, U.; Fercher, Adolf F.; Drexler, W.

    2005-08-01

    In vivo retinal imaging with ~ 8 μm axial resolution at 1030 nm is demonstrated for the first time, enabling enhanced penetration into the choroid. A new high power, broad bandwidth light source based on amplified spontaneous emission (NP Photonics, λc = 1030 nm, Δλ= 50 nm, Pout = 25 mW) has been interfaced to a time domain ophthalmic OCT system. In vivo retinal OCT tomograms performed at 800 nm are compared to those achieved at 1030 nm. Retinal OCT at longer wavelengths, e.g. 1030 nm significantly improves the visualization of the retinal pigment epithelium/choriocapillaris/choroid interface and might therefore provide new insight into choroidal/choriocapillary changes in age-related macular degeneration and other diseases of the retinal pigment epithelium (RPE)-choroid complex. 1030 nm OCT could also become a valuable tool in monitoring treatment effects on the choroids as in Verteporfin therapy.

  17. Structured oblique illumination microscopy for enhanced resolution imaging of non-fluorescent, coherently scattering samples.

    Science.gov (United States)

    Chowdhury, Shwetadwip; Dhalla, Al-Hafeez; Izatt, Joseph

    2012-08-01

    Many biological structures of interest are beyond the diffraction limit of conventional microscopes and their visualization requires application of super-resolution techniques. Such techniques have found remarkable success in surpassing the diffraction limit to achieve sub-diffraction limited resolution; however, they are predominantly limited to fluorescent samples. Here, we introduce a non-fluorescent analogue to structured illumination microscopy, termed structured oblique illumination microscopy (SOIM), where we use simultaneous oblique illuminations of the sample to multiplex high spatial-frequency content into the frequency support of the system. We introduce a theoretical framework describing how to demodulate this multiplexed information to reconstruct an image with a spatial-frequency support exceeding that of the system's classical diffraction limit. This approach allows enhanced-resolution imaging of non-fluorescent samples. Experimental confirmation of the approach is obtained in a reflection test target with moderate numerical aperture.

  18. Spread-Spectrum Coherent Acoustic Communication Between a Submarine and a Surface Ship

    NARCIS (Netherlands)

    Walree, P.A. van

    2004-01-01

    This paper describes an underwater acoustic communication experiment executed in the North Sea near Norway. A submarine broadcast direct-sequence spread-spectrum signals with data rates of 167 and 33 bit/s. The receiver station was a surface ship with a towed hydrophone array. As the platforms

  19. Macroscopic quantum coherence in a magnetic nanoparticle above the surface of a superconductor

    Science.gov (United States)

    Chudnovsky; Friedman

    2000-12-11

    We study macroscopic quantum tunneling of the magnetic moment in a single-domain particle placed above the surface of a superconductor. Such a setup allows one to manipulate the height of the energy barrier, preserving the degeneracy of the ground state. The tunneling amplitude and the effect of the dissipation in the superconductor are computed.

  20. Macroscopic Quantum Coherence in a Magnetic Nanoparticle Above the Surface of a Superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Chudnovsky, Eugene M.; Friedman, Jonathan R.

    2000-12-11

    We study macroscopic quantum tunneling of the magnetic moment in a single-domain particle placed above the surface of a superconductor. Such a setup allows one to manipulate the height of the energy barrier, preserving the degeneracy of the ground state. The tunneling amplitude and the effect of the dissipation in the superconductor are computed.

  1. Macroscopic Quantum Coherence in a Magnetic Nanoparticle Above the Surface of a Superconductor

    International Nuclear Information System (INIS)

    Chudnovsky, Eugene M.; Friedman, Jonathan R.

    2000-01-01

    We study macroscopic quantum tunneling of the magnetic moment in a single-domain particle placed above the surface of a superconductor. Such a setup allows one to manipulate the height of the energy barrier, preserving the degeneracy of the ground state. The tunneling amplitude and the effect of the dissipation in the superconductor are computed

  2. Enhancement of Friction against a Rough Surface by a Ridge-Channel Surface Microstructure.

    Science.gov (United States)

    Bai, Ying; Hui, Chung-Yuen; Levrard, Benjamin; Jagota, Anand

    2015-07-14

    We report on a study of the sliding friction of elastomeric surfaces patterned with ridges and channels (and unstructured flat controls), against both smooth and roughened spherical indenters. Against the smooth spherical indenter, all of the structured surfaces have highly reduced sliding friction due to the reduction in actual area of contact. Against roughened spherical indenters, however, the sliding force for structured samples can be up to 50% greater than that of an unstructured flat control. The mechanism of enhanced friction against a rough surface is due to a combination of increased actual area of contact, interlocking between roughness and the surface structure, and attendant dynamic instabilities that dissipate energy.

  3. Ultrasensitive detection of phenolic antioxidants by surface enhanced Raman spectroscopy

    Science.gov (United States)

    Ornelas-Soto, N.; Aguilar-Hernández, I. A.; Afseth, N.; López-Luke, T.; Contreras-Torres, F. F.; Wold, J. P.

    2017-08-01

    Surface-Enhanced Raman Spectroscopy (SERS) is a powerful surface-sensitive technique to study the vibrational properties of analytes at very low concentrations. In this study, ferulic acid, p-coumaric acid, caffeic acid and sinapic acid were analyzed by SERS using Ag colloids. Analytes were detected up to 2.5x10-9M. For caffeic acid and coumaric acid, this detection limit has been reached for the first time, as well as the SERS analysis of sinapic acid using silver colloids.

  4. Surface enhanced raman spectroscopy analytical, biophysical and life science applications

    CERN Document Server

    Schlücker, Sebastian

    2013-01-01

    Covering everything from the basic theoretical and practical knowledge to new exciting developments in the field with a focus on analytical and life science applications, this monograph shows how to apply surface-enhanced Raman scattering (SERS) for solving real world problems. From the contents: * Theory and practice of SERS * Analytical applications * SERS combined with other analytical techniques * Biophysical applications * Life science applications including various microscopies Aimed at analytical, surface and medicinal chemists, spectroscopists, biophysicists and materials scientists. Includes a Foreword by the renowned Raman spectroscopist Professor Wolfgang Kiefer, the former Editor-in-Chief of the Journal of Raman Spectroscopy.

  5. Heat Transfer Enhancement in Turbulent Flows by Blocked Surfaces

    Directory of Open Access Journals (Sweden)

    Onur YEMENİCİ

    2013-04-01

    Full Text Available In this study, the heat transfer analyses over flat and blocked surfaces were carried out in turbulent flow under the influence of the block height. A constant-temperature hot wire anemometer was used to the velocity and turbulent intensity measurements, while temperature values were measured by copper-constantan thermocouples. The average Stanton numbers for block heights of 15 and 25 mm were higher than those of flat surface by %38 and %84, respectively. The results showed that the presence of the blocks increased the heat transfer and the enhancement rose with block heights

  6. Enhanced truncated-correlation photothermal coherence tomography with application to deep subsurface defect imaging and 3-dimensional reconstructions

    Science.gov (United States)

    Tavakolian, Pantea; Sivagurunathan, Koneswaran; Mandelis, Andreas

    2017-07-01

    Photothermal diffusion-wave imaging is a promising technique for non-destructive evaluation and medical applications. Several diffusion-wave techniques have been developed to produce depth-resolved planar images of solids and to overcome imaging depth and image blurring limitations imposed by the physics of parabolic diffusion waves. Truncated-Correlation Photothermal Coherence Tomography (TC-PCT) is the most successful class of these methodologies to-date providing 3-D subsurface visualization with maximum depth penetration and high axial and lateral resolution. To extend the depth range and axial and lateral resolution, an in-depth analysis of TC-PCT, a novel imaging system with improved instrumentation, and an optimized reconstruction algorithm over the original TC-PCT technique is developed. Thermal waves produced by a laser chirped pulsed heat source in a finite thickness solid and the image reconstruction algorithm are investigated from the theoretical point of view. 3-D visualization of subsurface defects utilizing the new TC-PCT system is reported. The results demonstrate that this method is able to detect subsurface defects at the depth range of ˜4 mm in a steel sample, which exhibits dynamic range improvement by a factor of 2.6 compared to the original TC-PCT. This depth does not represent the upper limit of the enhanced TC-PCT. Lateral resolution in the steel sample was measured to be ˜31 μm.

  7. Nanosensors based on functionalized nanoparticles and surface enhanced raman scattering

    Science.gov (United States)

    Talley, Chad E.; Huser, Thomas R.; Hollars, Christopher W.; Lane, Stephen M.; Satcher, Jr., Joe H.; Hart, Bradley R.; Laurence, Ted A.

    2007-11-27

    Surface-Enhanced Raman Spectroscopy (SERS) is a vibrational spectroscopic technique that utilizes metal surfaces to provide enhanced signals of several orders of magnitude. When molecules of interest are attached to designed metal nanoparticles, a SERS signal is attainable with single molecule detection limits. This provides an ultrasensitive means of detecting the presence of molecules. By using selective chemistries, metal nanoparticles can be functionalized to provide a unique signal upon analyte binding. Moreover, by using measurement techniques, such as, ratiometric received SERS spectra, such metal nanoparticles can be used to monitor dynamic processes in addition to static binding events. Accordingly, such nanoparticles can be used as nanosensors for a wide range of chemicals in fluid, gaseous and solid form, environmental sensors for pH, ion concentration, temperature, etc., and biological sensors for proteins, DNA, RNA, etc.

  8. Applications of the surface enhanced Raman scattering (SERS)

    International Nuclear Information System (INIS)

    Picquart, M.; Haro P, E.; Bernard, S.

    2007-01-01

    Full text: Vibration spectroscopy techniques are used for many times to identify substances, determine molecular structure and quantify them, independently of their physical state. Raman spectroscopy as infrared absorption permit to access the vibration energy levels of molecules. In the second case, the permanent dipolar moment is involved while in the first one it is the polarizability (and the induced dipolar moment). Unfortunately, the classical Raman spectroscopy is low sensitive in particular in the case of biological molecules. On the opposite, the surface enhanced Raman spectroscopy (SERS) offers great potentialities. In this case, the molecules are adsorbed on a rough surface or on nanoparticles of gold or silver and the: signal can be increased by a factor of 10 7 to 10 8 . Moreover, the spectral enhancement is greater for the vibrations of the functional group of the molecule adsorbed on the substrate. In this work, we present the main theoretical bases of SERS, and some results obtain on different systems. (Author)

  9. Raman and Surface-Enhanced Raman Scattering for Biofilm Characterization

    Directory of Open Access Journals (Sweden)

    Seda Keleştemur

    2018-01-01

    Full Text Available Biofilms are a communal way of living for microorganisms in which microorganism cells are surrounded by extracellular polymeric substances (EPS. Most microorganisms can live in biofilm form. Since microorganisms are everywhere, understanding biofilm structure and composition is crucial for making the world a better place to live, not only for humans but also for other living creatures. Raman spectroscopy is a nondestructive technique and provides fingerprint information about an analyte of interest. Surface-enhanced Raman spectroscopy is a form of this technique and provides enhanced scattering of the analyte that is in close vicinity of a nanostructured noble metal surface such as silver or gold. In this review, the applications of both techniques and their combination with other biofilm analysis techniques for characterization of composition and structure of biofilms are discussed.

  10. Surface-enhanced Raman spectroscopy bioanalytical, biomolecular and medical applications

    CERN Document Server

    Procházka, Marek

    2016-01-01

    This book gives an overview of recent developments in RS and SERS for sensing and biosensing considering also limitations, possibilities and prospects of this technique. Raman scattering (RS) is a widely used vibrational technique providing highly specific molecular spectral patterns. A severe limitation for the application of this spectroscopic technique lies in the low cross section of RS. Surface-enhanced Raman scattering (SERS) spectroscopy overcomes this problem by 6-11 orders of magnitude enhancement compared with the standard RS for molecules in the close vicinity of certain rough metal surfaces. Thus, SERS combines molecular fingerprint specificity with potential single-molecule sensitivity. Due to the recent development of new SERS-active substrates, labeling and derivatization chemistry as well as new instrumentations, SERS became a very promising tool for many varied applications, including bioanalytical studies and sensing. Both intrinsic and extrinsic SERS biosensing schemes have been employed to...

  11. Spectral contrast-enhanced optical coherence tomography for improved detection of tumor microvasculature and functional imaging of lymphatic drainage

    Science.gov (United States)

    SoRelle, Elliott D.; Liba, Orly; Sen, Debasish; de la Zerda, Adam

    2017-03-01

    Optical Coherence Tomography (OCT) is well-suited to study in vivo dynamics of blood circulation and lymphatic flow because of the technique's combination of rapid image acquisition, micron spatial resolution, and penetration depth in turbid tissues. However, OCT has been historically constrained by a dearth of contrast agents that are readily distinguished from the strong scattering intrinsic to biological tissues. In this study, we demonstrate large gold nanorods (LGNRs) as optimized contrast agents for OCT. LGNRs produce 32-fold greater backscattering than GNRs previously tested for contrast-enhanced OCT. Furthermore, LGNRs exhibit 110-fold stronger spectral signal than conventional GNRs when coupled with custom spectral detection algorithms. This signal enhancement enables picomolar OCT detection sensitivity in vivo and single-particle detection against optically-clear backgrounds. Moreover, the ability to synthesize LGNRs with tunable spectral peaks provides a viable platform for multiplexed imaging studies. To explore the advantages of LGNRs as OCT contrast agents, we implemented them for noninvasive 3D imaging of tumor blood supply and active lymphatic drainage in mice. Spectral detection of LGNRs enabled 100% improvement in imaging depth for detecting microvasculature (vessels 20 μm in diameter) in U87MG glioblastoma xenografts in mice pinnae. We also demonstrated our approach's ability to map the spatial dependence of lymph drainage and flow directionality within lymphatic capillaries. Using LGNRs with distinct spectra, we further identified the functional states of individual lymphatic valves in vivo. Thus, this approach provides a powerful new platform for functional imaging that may be extended for future molecular imaging studies with OCT.

  12. Reactive surface organometallic complexes observed using dynamic nuclear polarization surface enhanced NMR spectroscopy

    KAUST Repository

    Pump, Eva

    2016-08-15

    Dynamic Nuclear Polarization Surface Enhanced NMR Spectroscopy (DNP SENS) is an emerging technique that allows access to high-sensitivity NMR spectra from surfaces. However, DNP SENS usually requires the use of radicals as an exogenous source of polarization, which has so far limited applications for organometallic surface species to those that do not react with the radicals. Here we show that reactive surface species can be studied if they are immobilized inside porous materials with suitably small windows, and if bulky nitroxide bi-radicals (here TEKPol) are used as the polarization source and which cannot enter the pores. The method is demonstrated by obtaining significant DNP enhancements from highly reactive complelxes [(equivalent to Si-O-)W(Me)(5)] supported on MCM-41, and effects of pore size (6.0, 3.0 and 2.5 nm) on the performance are discussed.

  13. Surface plasmon enhanced interfacial electron transfer and resonance Raman, surface-enhanced resonance Raman studies of cytochrome C mutants

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Junwei [Iowa State Univ., Ames, IA (United States)

    1999-11-08

    Surface plasmon resonance was utilized to enhance the electron transfer at silver/solution interfaces. Photoelectrochemical reductions of nitrite, nitrate, and CO2 were studied on electrochemically roughened silver electrode surfaces. The dependence of the photocurrent on photon energy, applied potential and concentration of nitrite demonstrates that the photoelectrochemical reduction proceeds via photoemission process followed by the capture of hydrated electrons. The excitation of plasmon resonances in nanosized metal structures resulted in the enhancement of the photoemission process. In the case of photoelectrocatalytic reduction of CO2, large photoelectrocatalytic effect for the reduction of CO2 was observed in the presence of surface adsorbed methylviologen, which functions as a mediator for the photoexcited electron transfer from silver metal to CO2 in solution. Photoinduced reduction of microperoxidase-11 adsorbed on roughened silver electrode was also observed and attributed to the direct photoejection of free electrons of silver metal. Surface plasmon assisted electron transfer at nanostructured silver particle surfaces was further determined by EPR method.

  14. Nanoscale Pillar-Enhanced Tribological Surfaces as Antifouling Membranes.

    Science.gov (United States)

    Choi, Wansuk; Chan, Edwin P; Park, Jong-Hyun; Ahn, Won-Gi; Jung, Hyun Wook; Hong, Seungkwan; Lee, Jong Suk; Han, Ji-Young; Park, Sangpil; Ko, Doo-Hyun; Lee, Jung-Hyun

    2016-11-16

    We present a nonconventional membrane surface modification approach that utilizes surface topography to manipulate the tribology of foulant accumulation on water desalination membranes via imprinting of submicron titanium dioxide (TiO 2 ) pillar patterns onto the molecularly structured, flat membrane surface. This versatile approach overcomes the constraint of the conventional approach relying on interfacial polymerization that inevitably leads to the formation of ill-defined surface topography. Compared to the nonpatterned membranes, the patterned membranes showed significantly improved fouling resistance for both organic protein and bacterial foulants. The use of hydrophilic TiO 2 as a pattern material increases the membrane hydrophilicity, imparting improved chemical antifouling resistance to the membrane. Fouling behavior was also interpreted in terms of the topographical effect depending on the relative size of foulants to the pattern dimension. In addition, computational fluid dynamics simulation suggests that the enhanced antifouling of the patterned membrane is attributed to the enhancement in overall and local shear stress at the fluid-TiO 2 pattern interface.

  15. Surface defects characterization in a quantum wire by coherent phonons scattering

    Energy Technology Data Exchange (ETDEWEB)

    Rabia, M. S. [Laboratoire de Mécanique des Structures et Energétique, Faculté du Génie de la Construction, Université. Mammeri de Tizi-Ouzou, BP 17 RP Hasnaoua II, Tizi-Ouzou 15000, Algérie m2msr@yahoo.fr (Algeria)

    2015-03-30

    The influence of surface defects on the scattering properties of elastic waves in a quasi-planar crystallographic waveguide is studied in the harmonic approximation using the matching method formalism. The structural model is based on three infinite atomic chains forming a perfect lattice surmounted by an atomic surface defect. Following the Landauer approach, we solve directly the Newton dynamical equation with scattering boundary conditions and taking into account the next nearest neighbour’s interaction. A detailed study of the defect-induced fluctuations in the transmission spectra is presented for different adatom masses. As in the electronic case, the presence of localized defect-induced states leads to Fano-like resonances. In the language of mechanical vibrations, these are called continuum resonances. Numerical results reveal the intimate relation between transmission spectra and localized defect states and provide a basis for the understanding of conductance spectroscopy experiments in disordered mesoscopic systems. The results could be useful for the design of phononic devices.

  16. Surface defects characterization in a quantum wire by coherent phonons scattering

    International Nuclear Information System (INIS)

    Rabia, M. S.

    2015-01-01

    The influence of surface defects on the scattering properties of elastic waves in a quasi-planar crystallographic waveguide is studied in the harmonic approximation using the matching method formalism. The structural model is based on three infinite atomic chains forming a perfect lattice surmounted by an atomic surface defect. Following the Landauer approach, we solve directly the Newton dynamical equation with scattering boundary conditions and taking into account the next nearest neighbour’s interaction. A detailed study of the defect-induced fluctuations in the transmission spectra is presented for different adatom masses. As in the electronic case, the presence of localized defect-induced states leads to Fano-like resonances. In the language of mechanical vibrations, these are called continuum resonances. Numerical results reveal the intimate relation between transmission spectra and localized defect states and provide a basis for the understanding of conductance spectroscopy experiments in disordered mesoscopic systems. The results could be useful for the design of phononic devices

  17. Active screen plasma nitriding enhances cell attachment to polymer surfaces

    International Nuclear Information System (INIS)

    Kaklamani, Georgia; Bowen, James; Mehrban, Nazia; Dong, Hanshan; Grover, Liam M.; Stamboulis, Artemis

    2013-01-01

    Active screen plasma nitriding (ASPN) is a well-established technique used for the surface modification of materials, the result of which is often a product with enhanced functional performance. Here we report the modification of the chemical and mechanical properties of ultra-high molecular weight poly(ethylene) (UHMWPE) using 80:20 (v/v) N 2 /H 2 ASPN, followed by growth of 3T3 fibroblasts on the treated and untreated polymer surfaces. ASPN-treated UHMWPE showed extensive fibroblast attachment within 3 h of seeding, whereas fibroblasts did not successfully attach to untreated UHMWPE. Fibroblast-coated surfaces were maintained for up to 28 days, monitoring their metabolic activity and morphology throughout. The chemical properties of the ASPN-treated UHMWPE surface were studied using X-ray photoelectron spectroscopy, revealing the presence of C-N, C=N, and C≡N chemical bonds. The elastic modulus, surface topography, and adhesion properties of the ASPN-treated UHMWPE surface were studied over 28 days during sample storage under ambient conditions and during immersion in two commonly used cell culture media.

  18. Surface Modification on Acoustic Wave Biosensors for Enhanced Specificity

    Directory of Open Access Journals (Sweden)

    Nathan D. Gallant

    2012-09-01

    Full Text Available Changes in mass loading on the surface of acoustic biosensors result in output frequency shifts which provide precise measurements of analytes. Therefore, to detect a particular biomarker, the sensor delay path must be judiciously designed to maximize sensitivity and specificity. B-cell lymphoma 2 protein (Bcl-2 found in urine is under investigation as a biomarker for non-invasive early detection of ovarian cancer. In this study, surface chemistry and biofunctionalization approaches were evaluated for their effectiveness in presenting antibodies for Bcl-2 capture while minimizing non-specific protein adsorption. The optimal combination of sequentially adsorbing protein A/G, anti-Bcl-2 IgG and Pluronic F127 onto a hydrophobic surface provided the greatest signal-to-noise ratio and enabled the reliable detection of Bcl-2 concentrations below that previously identified for early stage ovarian cancer as characterized by a modified ELISA method. Finally, the optimal surface modification was applied to a prototype acoustic device and the frequency shift for a range of Bcl-2 concentration was quantified to demonstrate the effectiveness in surface acoustic wave (SAW-based detection applications. The surface functionalization approaches demonstrated here to specifically and sensitively detect Bcl-2 in a working ultrasonic MEMS biosensor prototype can easily be modified to detect additional biomarkers and enhance other acoustic biosensors.

  19. Enhanced water repellency of surfaces coated with multiscale carbon structures

    Science.gov (United States)

    Marchalot, Julien; Ramos, Stella. M. M.; Pirat, Christophe; Journet, Catherine

    2018-01-01

    Low cost and well characterized superhydrophobic surfaces are frequently required for industrial applications. Materials are commonly structured at the micro or nano scale. Surfaces decorated with nanotube derivatives synthesized by plasma enhanced chemical vapor deposition (PECVD) are of particular interest, since suitable modifications in the growth parameters can lead to numerous designs. In this article, we present surfaces that are selected for their specific wetting features with patterns ranging from dense forests to jungles with concave (re-entrant) surface such as flake-like multiscale roughness. Once these surfaces are functionalized adequately, their wetting properties are investigated. Their ability to sustain a superhydrophobic state for sessile water drops is examined. Finally, we propose a design to achieve a robust so-called ;Fakir; state, even for micrometer-sized drops, whereas with classic nanotubes forests it is not achievable. Thus, the drop remains on the apex of the protrusions with a high contact angle and a low contact angle hysteresis, while the surface features demonstrate good mechanical resistance against capillary forces.

  20. Enhanced bone morphogenetic protein-2 performance on hydroxyapatite ceramic surfaces.

    Science.gov (United States)

    Schuessele, A; Mayr, H; Tessmar, J; Goepferich, A

    2009-09-15

    The immobilization of biomolecules on biomaterial surfaces allows for the control of their localization and retention. In numerous studies, proteins have been simply adsorbed to enhance the biological performance of various materials in vivo. We investigated the potential of surface modification techniques on hydroxyapatite (HA) ceramic discs in an in vitro approach. A novel method for protein immobilization was evaluated using the aminobisphosphonates pamidronate and alendronate, which are strong Ca chelating agents, and was compared with the established silanization technique. Lysozyme and bone morphogenetic protein-2 (BMP-2) were used to assess the suitability of the two surface modification methods with regard to the enzymatic activity of lysozyme and to the capacity of BMP-2 to stimulate the osteoblastic differentiation of C2C12 mouse myoblasts. After immobilization, a 2.5-fold increase in enzymatic activity of lysozyme was observed compared with the control. The alkaline phosphatase activity per cell stimulated by immobilized BMP-2 was 2.5-fold higher [9 x 10(-6) I.U.] than the growth factor on unmodified surfaces [2-4 x 10(-6) I.U.]. With regard to the increase in protein activity, both procedures lead to equivalent results. Thus, the bisphosphonate-based surface modification represents a safe and easy alternative for the attachment of proteins to HA surfaces. Copyright 2008 Wiley Periodicals, Inc.

  1. Surface-Enhanced Raman Scattering in Molecular Junctions.

    Science.gov (United States)

    Iwane, Madoka; Fujii, Shintaro; Kiguchi, Manabu

    2017-08-18

    Surface-enhanced Raman scattering (SERS) is a surface-sensitive vibrational spectroscopy that allows Raman spectroscopy on a single molecular scale. Here, we present a review of SERS from molecular junctions, in which a single molecule or molecules are made to have contact from the top to the bottom of metal surfaces. The molecular junctions are nice platforms for SERS as well as transport measurement. Electronic characterization based on the transport measurements of molecular junctions has been extensively studied for the development of miniaturized electronic devices. Simultaneous SERS and transport measurement of the molecular junctions allow both structural (geometrical) and electronic information on the single molecule scale. The improvement of SERS measurement on molecular junctions open the door toward new nanoscience and nanotechnology in molecular electronics.

  2. SURFACE-MODIFIED COALS FOR ENHANCED CATALYST DISPERSION AND LIQUEFACTION

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Yaw D. Yeboah

    1999-09-01

    This is the final report of the Department of Energy Sponsored project DE-FGF22-95PC95229 entitled, surface modified coals for enhanced catalyst dispersion and liquefaction. The aims of the study were to enhance catalyst loading and dispersion in coal for improved liquefaction by preadsorption of surfactants and catalysts on the coal and to train and educate minority scientists in catalysts and separation science. Illinois No. 6 Coal (DEC-24) was selected for the study. The surfactants investigated included dodecyl dimethyl ethyl ammonium bromide (DDAB), a cationic surfactant, sodium dodecyl sulfate, an anionic surfactant, and Triton x-100, a neutral surfactant. Ammonium molybdate tetrahydrate was used as the molybdenum catalyst precursor. Zeta potential, BET, FTIR, AFM, UV-Vis and luminescence intensity measurements were undertaken to assess the surface properties and the liquefaction activities of the coal. The parent coal had a net negative surface charge over the pH range 2-12. However, in the presence of DDAB the negativity of the surface charge decreased. At higher concentrations of DDAB, a positive surface charge resulted. In contrast to the effect of DDAB, the zeta potential of the coal became more negative than the parent coal in the presence of SDS. Adsorption of Triton reduced the net negative charge density of the coal samples. The measured surface area of the coal surface was about 30 m{sup 2}/g compared to 77m{sup 2}/g after being washed with deionized water. Addition of the surfactants decreased the surface area of the samples. Adsorption of the molybdenum catalyst increased the surface area of the coal sample. The adsorption of molybdenum on the coal was significantly promoted by preadsorption of DDAB and SDS. Molybdenum adsorption showed that, over a wide range of concentrations and pH values, the DDAB treated coal adsorbed a higher amount of molybdenum than the samples treated with SDS. The infrared spectroscopy (FTIR) and the atomic force

  3. A Global Map of Coherent M2 Internal Tide Surface Elevations

    Science.gov (United States)

    Ray, R. D.; Zaron, E. D.

    2014-12-01

    Satellite altimetry reveals small surface waves, with elevations of order 1 cm or smaller, associated with internal tides in the deep ocean. The global satellite data provide an unprecedented picture of such waves, potentially yielding much information about the ocean interior. Accurate knowledge of these waves is also needed for de-tiding altimetry in certain sensitive applications, including the future SWOT mission. Several approaches have been initiated recently to map these tiny waves, usually with some reliance on hydrographic information (e.g., recent work by Dushaw et al., 2011). Here we explore the feasibility of a purely empirical approach which avoids assumptions about stratification or modal wavelengths. A global elevation map is constructed based on tidal analysis of Topex/Poseidon, Jason, ERS-2, Envisat and GFO data. Small (order 5 mm) residuals, with wavelengths much longer than the baroclinic tide, appear unless now-standard along-track high-pass filters are applied, but filtering is shown to cause serious loss of information for east-west propagating waves (given typical track patterns). The technique is probably infeasible for S2 because of Envisat's and ERS's sun-synchronous orbits. Independent data from Cryosat-2 is used to validate the results. Applying our internal-tide 'correction' to Cryosat-2 data confirms a small reduction in variance in expected locations of significant internal tides.

  4. Surface Plasmons and Surface Enhanced Raman Spectra of Aggregated and Alloyed Gold-Silver Nanoparticles

    Directory of Open Access Journals (Sweden)

    Y. Fleger

    2009-01-01

    Full Text Available Effects of size, morphology, and composition of gold and silver nanoparticles on surface plasmon resonance (SPR and surface enhanced Raman spectroscopy (SERS are studied with the purpose of optimizing SERS substrates. Various gold and silver films made by evaporation and subsequent annealing give different morphologies and compositions of nanoparticles and thus different position of the SPR peak. SERS measurements of 4-mercaptobenzoic acid obtained from these films reveal that the proximity of the SPR peak to the exciting laser wavelength is not the only factor leading to the highest Raman enhancement. Silver nanoparticles evaporated on top of larger gold nanoparticles show higher SERS than gold-silver alloyed nanoparticles, in spite of the fact that the SPR peak of alloyed nanoparticles is narrower and closer to the excitation wavelength. The highest Raman enhancement was obtained for substrates with a two-peak particle size distribution for excitation wavelengths close to the SPR.

  5. Investigation into surface interaction between the contact lens, the upper eyelid and cornea using optical coherence tomography

    Science.gov (United States)

    Morecroft, R.; Carré, M. J.; Lewis, R.; Mylon, P.; Matcher, S. J.; Toomey, P.; Goff, J. E.; Maiti, R.

    2017-02-01

    Background and Aim: Over 50% of the total 125 million contact lens users complain of discomforts due to contact lenses. The aim of the project is to understand the effect of contact lenses on the morphological parameters of cornea and eyelid surfaces. Methods and results: Five volunteers were recruited for this study (3 soft contact lens users and 2 non-users). The volunteers were imaged using a slit lamp and Optical Coherence Tomography (OCT) before and after a period of 6-7 hours. There was a significant increase in epidermal thickness of the eyelid for contact lens users compared to non-users. In addition, the upper eyelid roughness for contact lens users and non-users increased significantly. This might be due to deposition of particles from the eyelid during the wiping process. Conclusions: Contact lens usage does affect the morphological parameters of eyelid. OCT is a powerful tool to measure these morphological changes in the eye. However, more volunteers must be recruited to get a better understanding of these changes.

  6. Enhanced perfume surface delivery to interfaces using surfactant surface multilayer structures.

    Science.gov (United States)

    Bradbury, Robert; Penfold, Jeffrey; Thomas, Robert K; Tucker, Ian M; Petkov, Jordan T; Jones, Craig

    2016-01-01

    Enhanced surface delivery and retention of perfumes at interfaces are the keys to their more effective and efficient deployment in a wide range of home and personal care related formulations. It has been previously demonstrated that the addition of multivalent counterions, notably Ca(2+), induces multilayer adsorption at the air-water interface for the anionic surfactant, sodium dodecyl-6-benzenesulfonate, LAS-6. Neutron reflectivity, NR, measurements are reported here which demonstrate that such surfactant surface multilayer structures are a potentially promising vehicle for enhanced delivery of perfumes to interfaces. The data show that the incorporation of the model perfumes, phenylethanol, PE, and linalool, LL, into the surface multilayer structure formed by LAS-6/Ca(2+) results in the surface structures being retained up to relatively high perfume mole fractions. Furthermore the amount of perfume at the surface is enhanced by at least an order of magnitude, compared to that co-adsorbed with a surfactant monolayer. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. Combination of optical coherence tomography and near infrared spectroscopy enhances determination of articular cartilage composition and structure

    NARCIS (Netherlands)

    Sarin, Jaakko K; Rieppo, Lassi; Brommer, Harold; Afara, Isaac O.; Saarakkala, Simo; Töyräs, Juha

    2017-01-01

    Conventional arthroscopic evaluation of articular cartilage is subjective and poorly reproducible. Therefore, implementation of quantitative diagnostic techniques, such as near infrared spectroscopy (NIRS) and optical coherence tomography (OCT), is essential. Locations (n = 44) with various

  8. Changes in choroidal thickness after prophylactic iridectomy in primary angle closure suspect eyes using enhanced depth imaging optical coherence tomography

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2015-01-01

    Full Text Available Purpose: The aim of the present study was to evaluate the effect of surgical peripheral iridectomy (SPI on choroidal thickness in primary angle-closure suspect (PACS eyes. Materials and Methods: This was a prospective observational case series of 30 subjects with PACS. Ocular biometry was performed before SPI (baseline and then 1 week later. Choroid was imaged by enhanced depth imaging optical coherence tomography (EDI-OCT. The choroidal thickness of the subfoveal area at 1 and 3 mm diameter around the fovea was determined. Central anterior chamber depth (ACD, lens thickness (LT, vitreous chamber depth (VCD, and axial length (AL were measured by A-scan ultrasound. Parameters were compared before SPI (baseline and 1 week later. Results: Thirty eyes of 30 patients with mean age of 61.53 ± 7.98 years were studied. There was no significant difference in the choroidal thickness at all macular locations before and after SPI (all P > 0.05. Mean subfoveal choroidal thickness was 279.61 μm ± 65.50 μm before and 274.54 μm ± 63.36 μm after SPI (P = 0.308. There was also no significant change in central ACD, LT, VCD, and LT after SPI (all P > 0.05. Conclusions: SPI does not appear to alter choroidal thickness in PACS eyes, as assessed using EDI-OCT. Long-term follow-up of PACS eyes treated with SPI may provide further insight into the effects of this treatment modality on the choroid.

  9. [Terahertz-band study on surface enhanced Raman scattering of nanoparticle].

    Science.gov (United States)

    Wu, Yu-Deng; Ren, Guang-Jun; Hao, Yun; Yao, Jian-Quan

    2013-05-01

    Study on surface-enhanced Raman scattering in the terahertz-band proved in that the terahertz-band Raman enhancement also exists. By studing principles of electromagnetic enhancement of surface-enhanced Raman scattering, using the finite difference time-domain method, the electromagnetic enhancement of surface enhanced Raman scattering of nano-particles irradiated by terahertz-wave was simulated, and the enhancement effect of terahertz waves was analyzed. Simulation experiments show that using finite-difference time-domain method could obtain effectively accurate simulation result of nano-particle scattering, proving that for terahertz waves, surface-enhanced effects on the surface of the nano-particle also exist. The results for surface enhanced Raman scattering extended from the visible and infrared to terahertz-band, and provide a basis for application of the combination of surface-enhanced Raman scattering and terahertz-wave.

  10. Nanostructured surface enhanced Raman scattering substrates for explosives detection

    DEFF Research Database (Denmark)

    Schmidt, Michael Stenbaek; Olsen, Jesper Kenneth; Boisen, Anja

    2010-01-01

    Here we present a method for trace detection of explosives in the gas phase using novel surface enhanced Raman scattering (SERS) spectroscopy substrates. Novel substrates that produce an exceptionally large enhancement of the Raman effect were used to amplify the Raman signal of explosives...... molecules adsorbed onto the substrate. The substrates were fabricated in a cleanroom process which only requires two steps to produce well controlled nano-sized high aspect ratio metal pillars. These substrates had superior chemical sensing performance in addition to a more cost effective fabrication...... process compared to existing commercial substrates. Therefore it is believed that these novel substrates will be able to make SERS more applicable in mobile explosives detection systems to be deployed in for example landmine clearance actions....

  11. Detection of volatile organic compounds using surface enhanced Raman scattering

    Energy Technology Data Exchange (ETDEWEB)

    Chang, A S; Maiti, A; Ileri, N; Bora, M; Larson, C C; Britten, J A; Bond, T C

    2012-03-22

    The authors present the detection of volatile organic compounds directly in their vapor phase by surface-enhanced Raman scattering (SERS) substrates based on lithographically-defined two-dimensional rectangular array of nanopillars. The type of nanopillars is known as the tapered pillars. For the tapered pillars, SERS enhancement arises from the nanofocusing effect due to the sharp tip on top. SERS experiments were carried out on these substrates using various concentrations of toluene vapor. The results show that SERS signal from a toluene vapor concentration of ppm level can be achieved, and the toluene vapor can be detected within minutes of exposing the SERS substrate to the vapor. A simple adsorption model is developed which gives results matching the experimental data. The results also show promising potential for the use of these substrates in environmental monitoring of gases and vapors.

  12. Plasmonic nanopillar structures for surface-enhanced raman scattering applications

    DEFF Research Database (Denmark)

    Rindzevicius, Tomas; Schmidt, Michael Stenbæk; Wu, Kaiyu

    2016-01-01

    Noble metal nanostructures support localized surface plasmon (LSPR) resonances that depend on their dimensions, shapes and compositions. Particle LSPR's can be used to spatially confine the incident light and produce enormous electromagnetic (EM) field enhancement spots, i.e. hot spots. Hot spots...... have been utilized in surfaceenhanced Raman spectroscopy (SERS) for biological and chemical sensing. We present Au nanopillar (NP) SERS structures that are excellent for molecular detection. The NP structures can be fabricated using a simple two-step process. We analyze NP optical properties...... experimentally and theoretically. Simulations show that that a single Agcoated NP supports two LSPR modes, i.e. the particle mode and the Ag cap resonant cavity mode. The Ag cap resonant cavity mode contributes most to the enhancement of the Raman scattering signal. The electric field distribution calculations...

  13. Horizontal silicon nanowires for surface-enhanced Raman spectroscopy

    Science.gov (United States)

    Gebavi, Hrvoje; Ristić, Davor; Baran, Nikola; Mikac, Lara; Mohaček-Grošev, Vlasta; Gotić, Marijan; Šikić, Mile; Ivanda, Mile

    2018-01-01

    The main purpose of this paper is to focus on details of the fabrication process of horizontally and vertically oriented silicon nanowires (SiNWs) substrates for the application of surface-enhanced Raman spectroscopy (SERS). The fabrication process is based on the vapor-liquid-solid method and electroless-assisted chemical etching, which, as the major benefit, resulting in the development of economical, easy-to-prepare SERS substrates. Furthermore, we examined the fabrication of Au coated Ag nanoparticles (NPs) on the SiNWs substrates in such a way as to diminish the influence of silver NPs corrosion, which, in turn, enhanced the SERS time stability, thus allowing for wider commercial applications. The substances on which high SERS sensitivity was proved are rhodamine (R6G) and 4-mercaptobenzoic acid (MBA), with the detection limits of 10-8 M and 10-6 M, respectively.

  14. A salutogenic program to enhance sense of coherence and quality of life for older people in the community: A feasibility randomized controlled trial and process evaluation.

    Science.gov (United States)

    Tan, Khoon Kiat; Chan, Sally Wai-Chi; Wang, Wenru; Vehviläinen-Julkunen, Katri

    2016-01-01

    To determine the feasibility of a salutogenesis-based self-care program on quality of life, sense of coherence, activation and resilience among older community dwellers. This is a feasibility randomized controlled trial. Sixty-four older community-dwellers were recruited from a Singapore senior activity center and randomly assigned to intervention and control groups. The intervention group attended a 12-week Resource Enhancement and Activation Program. The outcomes were assessed with the Chinese versions of World Health Organization Quality of Life Scale, Sense of Coherence, Patient Activation Measure, and Connor-Davidson Resilience Scale. Process evaluation was conducted using focus groups with the intervention group. At the end of the program, the intervention group showed significant improvement in the Sense of Coherence scale and the psychological subscale of the WHO Quality of Life scale compared with the control group. Three themes emerged from the process evaluation: participation in the program, reflection on the experience, and improving the experience. A salutogenic self-care approach could be a potential health promotion strategy for older people. With improved sense of coherence and psychological aspect of quality of life, older people's self-care ability may improve, leading to better health and better quality of life. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  15. Porous titania surfaces on titanium with hierarchical macro- and mesoporosities for enhancing cell adhesion, proliferation and mineralization.

    Science.gov (United States)

    Han, Guang; Müller, Werner E G; Wang, Xiaohong; Lilja, Louise; Shen, Zhijian

    2015-02-01

    Titanium received a macroporous titania surface layer by anodization, which contains open pores with average pore diameter around 5 μm. An additional mesoporous titania top layer following the contour of the macropores, of 100-200 nm thickness and with a pore diameter of 10nm, was formed by using the evaporation-induced self-assembly (EISA) method with titanium (IV) tetraethoxide as the precursor. A coherent laminar titania surface layer was thus obtained, creating a hierarchical macro- and mesoporous surface that was characterized by high-resolution electron microscopy. The interfacial bonding between the surface layers and the titanium matrix was characterized by the scratch test that confirmed a stable and strong bonding of titania surface layers on titanium. The wettability to water and the effects on the osteosarcoma cell line (SaOS-2) proliferation and mineralization of the formed titania surface layers were studied systematically by cell culture and scanning electron microscopy. The results proved that the porous titania surface with hierarchical macro- and mesoporosities was hydrophilic that significantly promoted cell attachment and spreading. A synergistic role of the hierarchical macro- and mesoporosities was revealed in terms of enhancing cell adhesion, proliferation and mineralization, compared with the titania surface with solo scale topography. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Engineering Plasmonic Nanopillar Arrays for Surface-enhanced Raman Spectroscopy

    DEFF Research Database (Denmark)

    Wu, Kaiyu

    This Ph.D. thesis presents (i) an in-depth understanding of the localized surface plasmon resonances (LSPRs) in the nanopillar arrays (NPs) for surface-enhanced Raman spectroscopy (SERS), and (ii) systematic ways of optimizing the fabrication process of NPs to improve their SERS efficiencies.......e., the particle mode and the cavity mode. The particle mode can be hybridized via leaning of pillars. The LSPR wavelength of the cavity mode is dominant only by the diameter of the Si pillar. The presence of a substrate dramatically changes the intensities of these two LSPR modes, by introducing constructive...... displaying a very large average SERS EF of >108. From a practical point of view, the developed SERS substrates are particularity interesting, since they are easy to handle and store and the fabrication is scalable, facilitating a wide and simple use of SERS in sensing applications....

  17. Porous titania surfaces on titanium with hierarchical macro- and mesoporosities for enhancing cell adhesion, proliferation and mineralization

    Energy Technology Data Exchange (ETDEWEB)

    Han, Guang [Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, 10691 Stockholm (Sweden); Müller, Werner E.G.; Wang, Xiaohong [ERC Advanced Grant Research Group at the Institute for Physiological Chemistry, University Medical Center of the Johannes Gutenberg University Mainz, Duesbergweg 6, D-55128 Mainz (Germany); Lilja, Louise [Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, 10691 Stockholm (Sweden); Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (Sweden); Shen, Zhijian, E-mail: shen@mmk.su.se [Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, 10691 Stockholm (Sweden)

    2015-02-01

    Titanium received a macroporous titania surface layer by anodization, which contains open pores with average pore diameter around 5 μm. An additional mesoporous titania top layer following the contour of the macropores, of 100–200 nm thickness and with a pore diameter of 10 nm, was formed by using the evaporation-induced self-assembly (EISA) method with titanium (IV) tetraethoxide as the precursor. A coherent laminar titania surface layer was thus obtained, creating a hierarchical macro- and mesoporous surface that was characterized by high-resolution electron microscopy. The interfacial bonding between the surface layers and the titanium matrix was characterized by the scratch test that confirmed a stable and strong bonding of titania surface layers on titanium. The wettability to water and the effects on the osteosarcoma cell line (SaOS-2) proliferation and mineralization of the formed titania surface layers were studied systematically by cell culture and scanning electron microscopy. The results proved that the porous titania surface with hierarchical macro- and mesoporosities was hydrophilic that significantly promoted cell attachment and spreading. A synergistic role of the hierarchical macro- and mesoporosities was revealed in terms of enhancing cell adhesion, proliferation and mineralization, compared with the titania surface with solo scale topography. - Highlights: • We developed a hierarchical macro- and mesoporous surface layer on titanium. • New surface layer was strong enough to sustain on implant surface. • New surface owned better surface wettability. • New surface can promote SaOS-2 cell adhesion, proliferation and mineralization. • Synergistic effects on cell responses occur when two porous structures coexist.

  18. Spectrally enhanced image resolution of tooth enamel surfaces

    Science.gov (United States)

    Zhang, Liang; Nelson, Leonard Y.; Berg, Joel H.; Seibel, Eric J.

    2012-01-01

    Short-wavelength 405 nm laser illumination of surface dental enamel using an ultrathin scanning fiber endoscope (SFE) produced enhanced detail of dental topography. The surfaces of human extracted teeth and artificial erosions were imaged with 405 nm, 444 nm, 532 nm, or 635 nm illumination lasers. The obtained images were then processed offline to compensate for any differences in the illumination beam diameters between the different lasers. Scattering and absorption coefficients for a Monte Carlo model of light propagation in dental enamel for 405 nm were scaled from published data at 532 nm and 633 nm. The value of the scattering coefficient used in the model was scaled from the coefficients at 532 nm and 633 nm by the inverse third power of wavelength. Simulations showed that the penetration depth of short-wavelength illumination is localized close to the enamel surface, while long-wavelength illumination travels much further and is backscattered from greater depths. Therefore, images obtained using short wavelength laser are not contaminated by the superposition of light reflected from enamel tissue at greater depths. Hence, the SFE with short-wavelength illumination may make it possible to visualize surface manifestations of phenomena such as demineralization, thus better aiding the clinician in the detection of early caries.

  19. Detection of explosive vapour using surface-enhanced Raman spectroscopy

    Science.gov (United States)

    Fang, X.; Ahmad, S. R.

    2009-11-01

    A commercially available nano-structured gold substrate was used for activating surface-enhanced Raman scattering (SERS). Raman spectra of the vapour of explosive material, triacetonetriperoxide (TATP), at trace concentrations produced from adsorbed molecules on such surfaces have been studied. Prominent Raman lines of the explosive molecular species were recorded at a sample temperature of ˜35°C, which is near to human body temperature. For this study, the concentration of the adsorbed TATP molecules on the nano-structured surface was varied by heating the sample to different temperatures and exposing the substrate to the sample vapour for different lengths of time. The intensities of the Raman lines have been found to increase with the increase in temperature and also with the increase in the duration of exposure for a fixed temperature. However, as expected, the Raman intensities have been found to saturate at higher temperatures and longer exposures. These saturation effects of the strengths of the Raman lines in the SERS of TATP vapour have been investigated in this paper. The results indicate that the optimisation for vapour deposition on the surface could be a crucial factor for any quantitative estimate of the concentration of the molecular species adsorbed on the nano-structured substrates.

  20. Nanoscale array structures suitable for surface enhanced raman scattering and methods related thereto

    Science.gov (United States)

    Bond, Tiziana C.; Miles, Robin; Davidson, James C.; Liu, Gang Logan

    2014-07-22

    Methods for fabricating nanoscale array structures suitable for surface enhanced Raman scattering, structures thus obtained, and methods to characterize the nanoscale array structures suitable for surface enhanced Raman scattering. Nanoscale array structures may comprise nanotrees, nanorecesses and tapered nanopillars.

  1. Surface enhanced Raman scattering (SERS) fabrics for trace analysis

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jun [National Engineering Laboratory for Advanced Yarn and Fabric Formation and Clean Production, Wuhan Textile University, Wuhan 430073 (China); Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials & Key Laboratory for the Synthesis and Application of Organic Functional Molecules, Ministry of Education & College of Chemistry & Chemical Engineering, Hubei University, Wuhan 430062 (China); Zhou, Ji [Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials & Key Laboratory for the Synthesis and Application of Organic Functional Molecules, Ministry of Education & College of Chemistry & Chemical Engineering, Hubei University, Wuhan 430062 (China); Tang, Bin, E-mail: bin.tang@deakin.edu.au [National Engineering Laboratory for Advanced Yarn and Fabric Formation and Clean Production, Wuhan Textile University, Wuhan 430073 (China); Institute for Frontier Materials, Deakin University, Geelong, Victoria 3216 (Australia); Zeng, Tian; Li, Yaling [Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials & Key Laboratory for the Synthesis and Application of Organic Functional Molecules, Ministry of Education & College of Chemistry & Chemical Engineering, Hubei University, Wuhan 430062 (China); Li, Jingliang [Institute for Frontier Materials, Deakin University, Geelong, Victoria 3216 (Australia); Ye, Yong, E-mail: yeyong@hubu.edu.cn [Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials & Key Laboratory for the Synthesis and Application of Organic Functional Molecules, Ministry of Education & College of Chemistry & Chemical Engineering, Hubei University, Wuhan 430062 (China); Wang, Xungai [National Engineering Laboratory for Advanced Yarn and Fabric Formation and Clean Production, Wuhan Textile University, Wuhan 430073 (China); Institute for Frontier Materials, Deakin University, Geelong, Victoria 3216 (Australia)

    2016-11-15

    Highlights: • Gold nanoparticles are in-situ synthesized on silk fabrics by heating. • Flexible silk fabrics with gold nanoparticles are used for surface-enhanced Raman scattering (SERS). • SERS activities of silk fabrics with different gold contents are investigated. - Abstract: Flexible SERS active substrates were prepared by modification of silk fabrics with gold nanoparticles. Gold nanoparticles were in-situ synthesized after heating the silk fabrics immersed in gold ion solution. Localized surface plasmon resonance (LSPR) properties of the treated silk fabrics varied as the concentration of gold ions changed, in relation to the morphologies of gold nanoparticles on silk. In addition, X-ray diffraction (XRD) was used to observe the structure of the gold nanoparticle treated silk fabrics. The SERS enhancement effect of the silk fabrics treated with gold nanoparticles was evaluated by collecting Raman signals of different concentrations of p-aminothiophenol (PATP), 4-mercaptopyridine (4-MPy) and crystal violet (CV) solutions. The results demonstrate that the silk fabrics corresponding to 0.3 and 0.4 mM of gold ions possess high SERS activity compared to the other treated fabrics. It is suggested that both the gold content and morphologies of gold nanoparticles dominate the SERS effect of the treated silk fabrics.

  2. [Surface-enhanced Raman spectroscopy analysis of thiabendazole pesticide].

    Science.gov (United States)

    Lin, Lei; Wu, Rui-mei; Liu, Mu-hua; Wang, Xiao-bin; Yan, Lin-yuan

    2015-02-01

    Surface-enhanced Raman spectroscopy (SERS) technique was used to analyze the Raman peaks of thiabendazole pesticides in the present paper. Surface enhanced substrates of silver nanoparticle were made based on microwave technology. Raman signals of thiabendazole were collected by laser Micro-Raman spectrometer with 514. 5 and 785 nm excitation wavelengths, respectively. The Raman peaks at different excitation wavelengths were analyzed and compared. The Raman peaks 782 and 1 012 at 785 nm excitation wavelength were stronger, which were C--H out-of-plane vibrations. While 1284, 1450 and 1592 cm(-1) at 514.5 nm excitation wavelength were stronger, which were vng and C==N stretching. The study results showed that the intensity of Raman peak and Raman shift at different excitation wavelengths were different And strong Raman signals were observed at 782, 1012, 1284, 1450 and 1592 cm(-1) at 514.5 and 785 nm excitation wavelengths. These characteristic vibrational modes are characteristic Raman peaks of carbendazim pesticide. The results can provide basis for the rapid screening of pesticide residue in agricultural products and food based on Raman spectrum.

  3. Surface enhanced Raman scattering (SERS) fabrics for trace analysis

    International Nuclear Information System (INIS)

    Liu, Jun; Zhou, Ji; Tang, Bin; Zeng, Tian; Li, Yaling; Li, Jingliang; Ye, Yong; Wang, Xungai

    2016-01-01

    Highlights: • Gold nanoparticles are in-situ synthesized on silk fabrics by heating. • Flexible silk fabrics with gold nanoparticles are used for surface-enhanced Raman scattering (SERS). • SERS activities of silk fabrics with different gold contents are investigated. - Abstract: Flexible SERS active substrates were prepared by modification of silk fabrics with gold nanoparticles. Gold nanoparticles were in-situ synthesized after heating the silk fabrics immersed in gold ion solution. Localized surface plasmon resonance (LSPR) properties of the treated silk fabrics varied as the concentration of gold ions changed, in relation to the morphologies of gold nanoparticles on silk. In addition, X-ray diffraction (XRD) was used to observe the structure of the gold nanoparticle treated silk fabrics. The SERS enhancement effect of the silk fabrics treated with gold nanoparticles was evaluated by collecting Raman signals of different concentrations of p-aminothiophenol (PATP), 4-mercaptopyridine (4-MPy) and crystal violet (CV) solutions. The results demonstrate that the silk fabrics corresponding to 0.3 and 0.4 mM of gold ions possess high SERS activity compared to the other treated fabrics. It is suggested that both the gold content and morphologies of gold nanoparticles dominate the SERS effect of the treated silk fabrics.

  4. Plasma surface interactions in Q-enhanced mirror systems

    International Nuclear Information System (INIS)

    Post, R.F.

    1978-01-01

    Two approaches to enhancement of the Q (energy gain) factor of mirror systems are under study at Livermore. These include the Tandem Mirror and the Field Reversed Mirror. Both of these new ideas preserve features of conventional mirror systems as far as plasma-wall interactions are concerned. Specifically in both approaches field lines exit from the ends of the system and impinge on walls located at a distance from the confinement chamber. It is possible to predict some aspects of the plasma/surface interactions of TM and FRM systems from experience obtained in the Livermore 2XIIB experiment. In particular, as observed in 2XIIB, effective isolation of the plasma from thermal contact with the ends owing to the development of sheath-like regions is to be expected. Studies presently underway directed toward still further enhancing the decoupling of the plasma from the effects of plasma surface interactions at the walls will be discussed, with particular reference to the problem of minimizing the effects of refluxing secondary electrons produced by plasma impact on the end walls

  5. Electromagnetic theories of surface-enhanced Raman spectroscopy.

    Science.gov (United States)

    Ding, Song-Yuan; You, En-Ming; Tian, Zhong-Qun; Moskovits, Martin

    2017-07-07

    Surface-enhanced Raman spectroscopy (SERS) and related spectroscopies are powered primarily by the concentration of the electromagnetic (EM) fields associated with light in or near appropriately nanostructured electrically-conducting materials, most prominently, but not exclusively high-conductivity metals such as silver and gold. This field concentration takes place on account of the excitation of surface-plasmon (SP) resonances in the nanostructured conductor. Optimizing nanostructures for SERS, therefore, implies optimizing the ability of plasmonic nanostructures to concentrate EM optical fields at locations where molecules of interest reside, and to enhance the radiation efficiency of the oscillating dipoles associated with these molecules and nanostructures. This review summarizes the development of theories over the past four decades pertinent to SERS, especially those contributing to our current understanding of SP-related SERS. Special emphasis is given to the salient strategies and theoretical approaches for optimizing nanostructures with hotspots as efficient EM near-field concentrating and far-field radiating substrates for SERS. A simple model is described in terms of which the upper limit of the SERS enhancement can be estimated. Several experimental strategies that may allow one to approach, or possibly exceed this limit, such as cascading the enhancement of the local and radiated EM field by the multiscale EM coupling of hierarchical structures, and generating hotspots by hybridizing an antenna mode with a plasmonic waveguide cavity mode, which would result in an increased local field enhancement, are discussed. Aiming to significantly broaden the application of SERS to other fields, and especially to material science, we consider hybrid structures of plasmonic nanostructures and other material phases and strategies for producing strong local EM fields at desired locations in such hybrid structures. In this vein, we consider some of the numerical

  6. Characterization of wet pad surface in chemical mechanical polishing (CMP) process with full-field optical coherence tomography (FF-OCT).

    Science.gov (United States)

    Choi, Woo June; Jung, Sung Pyo; Shin, Jun Geun; Yang, Danning; Lee, Byeong Ha

    2011-07-04

    Chemical mechanical polishing (CMP) is a key process for global planarization of silicon wafers for semiconductors and AlTiC wafers for magnetic heads. Removal rate of wafer material is directly dependent on the surface roughness of a CMP pad, thus the structure of the pad surface has been evaluated with variable techniques. However, under in situ CMP process, the measurements have been severely limited due to the existence of polishing fluids including the slurry on the pad surface. In here, we newly introduce ultra-high resolution full-field optical coherence tomography (FF-OCT) to investigate the surface of wet pads. With FF-OCT, the wet pad surface could be quantitatively characterized in terms of the polishing pad lifetime, and also be three-dimensionally visualized. We found that reasonable polishing span could be evaluated from the surface roughness measurement and the groove depth measurement made by FF-OCT.

  7. In situ surface-enhanced Raman spectroelectrochemical analysis system with a hemin modified nanostructured gold surface.

    Science.gov (United States)

    Yuan, Tao; Le Thi Ngoc, Loan; van Nieuwkasteele, Jan; Odijk, Mathieu; van den Berg, Albert; Permentier, Hjalmar; Bischoff, Rainer; Carlen, Edwin T

    2015-03-03

    An integrated surface-enhanced Raman scattering (SERS) spectroelectrochemical (SEC) analysis system is presented that combines a small volume microfluidic sample chamber (Raman spectroelectrochemistry. The SEC system includes a nanostructured Au surface that serves dual roles as the electrochemical working electrode (WE) and SERS substrate, a microfabricated Pt counter electrode (CE), and an external Ag/AgCl reference electrode (RE). The nanostructured Au WE enables highly sensitive in situ SERS spectroscopy through large and reproducible SERS enhancements, which eliminates the need for resonant wavelength matching of the laser excitation source with the electronic absorption of the target molecule. The new SEC analysis system has the merits of wide applicability to target molecules, small sample volume, and a low detection limit. We demonstrate in situ SERS spectroelectrochemistry measurements of the metalloporphyrin hemin showing shifts of the iron oxidation marker band ν4 with the nanostructured Au working electrode under precise potential control.

  8. Gas detection by means of surface plasmon resonance enhanced ellipsometry

    Energy Technology Data Exchange (ETDEWEB)

    Nooke, Alida

    2012-11-01

    This thesis investigated gas sensing by means of surface plasmon resonance enhanced ellipsometry. Surface plasmons were excited in a 40 - 50 nm gold layer by a He-Ne-laser using the Kretschmann configuration, which was arranged on a self-made copper measuring cell. A fixed angle of incidence and the ellipsometric parameter {Delta} as the measured value were used to monitor changes in the gas phase. Different types of gases were investigated: flammable (hydrocarbons and hydrogen), oxidising (oxygen and ozone), toxic (carbon monoxide) and inert (helium and nitrogen). The gas types can be distinguished by their refractive indices, whereas the sensor responds instantly relative to the reference gas with an increase or a decrease in {Delta}. Diluting the analyte gas with a reference gas (nitrogen or air) allowed the detection limits to be determined, these lay in the low % range. The sensor stability was also enhanced as well as the sensitivity by modifying the gold layers with a 3-10 nm additional layer. These additional layers consisted of the inorganic materials TiO{sub 2}, ZrO{sub 2}, MgF{sub 2} and Fe: SnO{sub 2} which were deposited by different coating processes. Surface investigations were made of every utilised layer: scanning electron microscope and atomic force microscope measurements for surface topology and spectroscopic ellipsometry mapping to determine the optical constants and the layer thicknesses. All applied materials protected the gold layer from contaminations and thus prolonged the life span of the sensor. Furthermore, the detection limits were reduced significantly, to the low ppm range. The material Fe: SnO{sub 2} demonstrates a special behaviour in reaction with the toxic gas carbon monoxide: Due to the iron doping, the response to carbon monoxide is extraordinary and concentrations below 1 ppm were detected. In order to approach a future application in industry, the sensor system was adapted to a stainless steel tube. With this measuring

  9. Nanostructure-enhanced surface plasmon resonance imaging (Conference Presentation)

    Science.gov (United States)

    Špašková, Barbora; Lynn, Nicholas S.; Slabý, Jiří Bocková, Markéta; Homola, Jiří

    2017-06-01

    There remains a need for the multiplexed detection of biomolecules at extremely low concentrations in fields of medical diagnostics, food safety, and security. Surface plasmon resonance imaging is an established biosensing approach in which the measurement of the intensity of light across a sensor chip is correlated with the amount of target biomolecules captured by the respective areas on the chip. In this work, we present a new approach for this method allowing for enhanced bioanalytical performance via the introduction of nanostructured sensing chip and polarization contrast measurement, which enable the exploitation of both amplitude and phase properties of plasmonic resonances on the nanostructures. Here we will discuss a complex theoretical analysis of the sensor performance, whereby we investigate aspects related to both the optical performance as well as the transport of the analyte molecules to the functionalized surfaces. This analysis accounts for the geometrical parameters of the nanostructured sensing surface, the properties of functional coatings, and parameters related to the detection assay. Based on the results of the theoretical analysis, we fabricated sensing chips comprised of arrays of gold nanoparticles (by electron-beam lithography), which were modified by a biofunctional coating to allow for the selective capturing of the target biomolecules in the regions with high sensitivity. In addition, we developed a compact optical reader with an integrated microfluidic cell, allowing for the measurement from 50 independent sensing channels. The performance of this biosensor is demonstrated through the sensitive detection of short oligonucleotides down to the low picomolar level.

  10. Analysis of polymer surfaces and thin-film coatings with Raman and surface enhanced Raman scattering

    CERN Document Server

    McAnally, G D

    2001-01-01

    This thesis investigates the potential of surface-enhanced Raman scattering (SERS) for the analysis and characterisation of polymer surfaces. The Raman and SERS spectra from a PET film are presented. The SERS spectra from the related polyester PBT and from the monomer DMT are identical to PET, showing that only the aromatic signals are enhanced. Evidence from other compounds is presented to show that loss of the carbonyl stretch (1725 cm sup - sup 1) from the spectra is due to a chemical interaction between the silver and surface carbonyl groups. The interaction of other polymer functional groups with silver is discussed. A comparison of Raman and SERS spectra collected from three faces of a single crystal shows the SERS spectra are depolarised. AFM images of the silver films used to obtain SERS are presented. They consist of regular islands of silver, fused together to form a complete film. The stability and reproducibility and of these surfaces is assessed. Band assignments for the SERS spectrum of PET are ...

  11. Surface Plasmon Enhanced Phosphorescent Organic Light Emitting Diodes

    International Nuclear Information System (INIS)

    Bazan, Guillermo; Mikhailovsky, Alexander

    2008-01-01

    The objective of the proposed work was to develop the fundamental understanding and practical techniques for enhancement of Phosphorescent Organic Light Emitting Diodes (PhOLEDs) performance by utilizing radiative decay control technology. Briefly, the main technical goal is the acceleration of radiative recombination rate in organometallic triplet emitters by using the interaction with surface plasmon resonances in noble metal nanostructures. Increased photonic output will enable one to eliminate constraints imposed on PhOLED efficiency by triplet-triplet annihilation, triplet-polaron annihilation, and saturation of chromophores with long radiative decay times. Surface plasmon enhanced (SPE) PhOLEDs will operate more efficiently at high injection current densities and will be less prone to degradation mechanisms. Additionally, introduction of metal nanostructures into PhOLEDs may improve their performance due to the improvement of the charge transport through organic layers via multiple possible mechanisms ('electrical bridging' effects, doping-like phenomena, etc.). SPE PhOLED technology is particularly beneficial for solution-fabricated electrophosphorescent devices. Small transition moment of triplet emitters allows achieving a significant enhancement of the emission rate while keeping undesirable quenching processes introduced by the metal nanostructures at a reasonably low level. Plasmonic structures can be introduced easily into solution-fabricated PhOLEDs by blending and spin coating techniques and can be used for enhancement of performance in existing device architectures. This constitutes a significant benefit for a large scale fabrication of PhOLEDs, e.g. by roll-to-roll fabrication techniques. Besides multieexciton annihilation, the power efficacy of PhOLEDs is often limited by high operational bias voltages required for overcoming built-in potential barriers to injection and transport of electrical charges through a device. This problem is especially

  12. Surface Plasmon Enhanced Phosphorescent Organic Light Emitting Diodes

    Energy Technology Data Exchange (ETDEWEB)

    Guillermo Bazan; Alexander Mikhailovsky

    2008-08-01

    The objective of the proposed work was to develop the fundamental understanding and practical techniques for enhancement of Phosphorescent Organic Light Emitting Diodes (PhOLEDs) performance by utilizing radiative decay control technology. Briefly, the main technical goal is the acceleration of radiative recombination rate in organometallic triplet emitters by using the interaction with surface plasmon resonances in noble metal nanostructures. Increased photonic output will enable one to eliminate constraints imposed on PhOLED efficiency by triplet-triplet annihilation, triplet-polaron annihilation, and saturation of chromophores with long radiative decay times. Surface plasmon enhanced (SPE) PhOLEDs will operate more efficiently at high injection current densities and will be less prone to degradation mechanisms. Additionally, introduction of metal nanostructures into PhOLEDs may improve their performance due to the improvement of the charge transport through organic layers via multiple possible mechanisms ('electrical bridging' effects, doping-like phenomena, etc.). SPE PhOLED technology is particularly beneficial for solution-fabricated electrophosphorescent devices. Small transition moment of triplet emitters allows achieving a significant enhancement of the emission rate while keeping undesirable quenching processes introduced by the metal nanostructures at a reasonably low level. Plasmonic structures can be introduced easily into solution-fabricated PhOLEDs by blending and spin coating techniques and can be used for enhancement of performance in existing device architectures. This constitutes a significant benefit for a large scale fabrication of PhOLEDs, e.g. by roll-to-roll fabrication techniques. Besides multieexciton annihilation, the power efficacy of PhOLEDs is often limited by high operational bias voltages required for overcoming built-in potential barriers to injection and transport of electrical charges through a device. This problem is

  13. Chloride ion-dependent surface-enhanced Raman scattering study of biotin on the silver surface

    International Nuclear Information System (INIS)

    Liu Fangfang; Gu Huaimin; Yuan Xiaojuan; Dong Xiao; Lin Yue

    2011-01-01

    In the present paper, the surface enhanced Raman scattering (SERS) technique was employed to study the SERS spectra of biotin molecules formed on the silver surface. The adsorption geometries of biotin molecules on the silver surface were analyzed based on the SERS data. It can be found that most vibration modes show a Raman shift in silver sol after the addition of sodium chloride solution. In addition, The Raman signals of biotin become weaker and weaker with the increase of the concentration of sodium chloride. This may be due to that the interaction between chloride ions and silver particles is stronger than the interaction between biotin molecules and silver particles. When the concentration of sodium chloride in silver colloid is higher than 0.05mol/L, superfluous chloride ions may form an absorption layer so that biotin can not be adsorbed on silver surface directly. The changes in intensity and profile shape in the SERS spectra suggest different adsorption behavior and surface-coverage of biotin on silver surface. The SERS spectra of biotin suggest that the contribution of the charge transfer mechanism to SERS may be dominant.

  14. Surface-enhanced Raman Scattering Enhancement Factors for RNA Mononucleotides on Silver Nanoparticles

    Directory of Open Access Journals (Sweden)

    Snežana Miljanić

    2015-12-01

    Full Text Available Surface-enhanced Raman scattering (SERS enhancement factors (EF were evaluated for RNA mononucleotides: adenosine 5'-monophosphate (AMP, guanosine 5'-monophosphate (GMP, cytidine 5'-monophosphate (CMP and uridine 5'-monophosphate (UMP, on silver nanoparticles, which differed in shape (nanospheres, nanostars and stabilizing anionic layer (chlorides, citrates on the metal surface. In freshly prepared silver colloids the enhanced Raman scattering was observed for all the RNA mononucleotides on the chloride coated silver nanospheres, Ag_Cl nsp (EF ≈ 104, for AMP only on the citrate coated silver nanospheres, Ag_cit nsp (EF ≈ 103, while not obtained at all for any of the mononucleotides on the citrate stabilized silver nanostars, Ag_cit nst. Upon aggregation, the SERS activity of all the silver colloids increased, whereby the purine mononucleotides, AMP and GMP, more strongly scattered radiation on Ag_Cl nsp, and the pyrimidine mononucleotides, CMP and UMP, on Ag_cit nsp. Regardless of the silver nanoparticles, the higher EFs were evaluated for AMP and GMP (EF up to 5 × 106, than for CMP and UMP (EF ≈ 5 × 104.

  15. Surface-enhanced Raman fiberoptic sensors for remote monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Stokes, D.L.; Alarie, J.P.; Vo-Dinh, T. [Oak Ridge National Lab., TN (United States). Health Sciences Research Div.

    1995-09-01

    A new sensor design for remote surface-enhanced Raman scattering (SERS) measurements has been developed for environmental applications. The design features the modification of an optical fiber using layers of alumina microparticles and silver coatings for inducing the SERS effect at the sensing probe. A single fiber carries both the laser excitation and the SERS signal radiation, keeping optical parameters at the remote tip simple and consistent. The small tip size achievable with this configuration also demonstrates potential of this new design as a microsensor for in-situ measurement in microenvironments. Details of sensor tip fabrication and optical system design are described. SERS spectra of aqueous environmental samples acquired in-situ using the SERS sensor are also presented to illustrate the effectiveness of the SERS sensor.

  16. Detection of explosives based on surface-enhanced Raman spectroscopy.

    Science.gov (United States)

    Wackerbarth, Hainer; Salb, Christian; Gundrum, Lars; Niederkrüger, Matthias; Christou, Konstantin; Beushausen, Volker; Viöl, Wolfgang

    2010-08-10

    In this study we present a device based on surface-enhanced Raman scattering (SERS) for the detection of airborne explosives. The explosives are resublimated on a cooled nanostructured gold substrate. The explosives trinitrotoluene (TNT) and triacetone triperoxide (TATP) are used. The SERS spectrum of the explosives is analyzed. Thus, TNT is deposited from an acetonitrile solution on the gold substrate. In the case of TATP, first the bulk TATP Raman spectrum was recorded and compared with the SERS spectrum, generated by deposition out of the gas phase. The frequencies of the SERS spectrum are hardly shifted compared to the spectrum of bulk TATP. The influence of the nanostructured gold substrate temperature on the signals of TATP was studied. A decrease in temperature up to 200 K increased the intensities of the TATP bands in the SERS spectrum; below 200 K, the TATP fingerprint disappeared.

  17. Silicon nanohybrid-based surface-enhanced Raman scattering sensors.

    Science.gov (United States)

    Wang, Houyu; Jiang, Xiangxu; Lee, Shuit-Tong; He, Yao

    2014-11-01

    Nanomaterial-based surface-enhanced Raman scattering (SERS) sensors are highly promising analytical tools, capable of ultrasensitive, multiplex, and nondestructive detection of chemical and biological species. Extensive efforts have been made to design various silicon nanohybrid-based SERS substrates such as gold/silver nanoparticle (NP)-decorated silicon nanowires, Au/Ag NP-decorated silicon wafers (AuNP@Si), and so forth. In comparison to free AuNP- and AgNP-based SERS sensors, the silicon nanohybrid-based SERS sensors feature higher enhancement factors (EFs) and excellent reproducibility, since SERS hot spots are efficiently coupled and stabilized through interconnection to the semiconducting silicon substrates. Consequently, in the past decade, giant advancements in the development of silicon nanohybrid-based SERS sensors have been witnessed for myriad sensing applications. In this review, the representative achievements related to the design of high-performance silicon nanohybrid-based SERS sensors and their use for chemical and biological analysis are reviewed in a detailed way. Furthermore, the major opportunities and challenges in this field are discussed from a broad perspective and possible future directions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Plasmonic dimer antennas for surface enhanced Raman scattering.

    Science.gov (United States)

    Höflich, Katja; Becker, Michael; Leuchs, Gerd; Christiansen, Silke

    2012-05-11

    Electron beam induced deposition (EBID) has recently been developed into a method to directly write optically active three-dimensional nanostructures. For this purpose a metal-organic precursor gas (here dimethyl-gold(III)-acetylacetonate) is introduced into the vacuum chamber of a scanning electron microscope where it is cracked by the focused electron beam. Upon cracking the aforementioned precursor gas, 3D deposits are realized, consisting of gold nanocrystals embedded in a carbonaceous matrix. The carbon content in the deposits hinders direct plasmonic applications. However, it is possible to activate the deposited nanostructures for plasmonics by coating the EBID structures with a continuous silver layer of a few nanometers thickness. Within this silver layer collective motions of the free electron gas can be excited. In this way, EBID structures with their intriguing precision at the nanoscale have been arranged in arrays of free-standing dimer antenna structures with nanometer sized gaps between the antennas that face each other with an angle of 90°. These dimer antenna ensembles can constitute a reproducibly manufacturable substrate for exploiting the surface enhanced Raman effect (SERS). The achieved SERS enhancement factors are of the order of 10⁴ for the incident laser light polarized along the dimer axes. To prove the signal enhancement in a Raman experiment we used the dye methyl violet as a robust test molecule. In future applications the thickness of such a silver layer on the dimer antennas can easily be varied for tuning the plasmonic resonances of the SERS substrate to match the resonance structure of the analytes to be detected.

  19. Enhancement of focused jets by using surface microbubbles

    Science.gov (United States)

    Yukisada, Ryosuke; Kiyama, Akihito; Zhang, Xuehua; Tagawa, Yoshiyuki

    2017-11-01

    Focused liquid jets are important for various key technologies, such as material deposition and automated pipetting. It has been challenging to create high speed jets of viscous liquids. Our latest work showed that it is possible to generate viscous jets by applying sudden acceleration to the liquid (Onuki et al., J. J. Multi. Flow, 2015). It was observed that under certain conditions cavitation bubbles form in the liquid, making important contribution to the increment of jet velocity (Kiyama et al., JFM, 2016). The increased velocity depends on the maximum size of expanding bubbles. Thus, for controlling the velocity of focused jets, it is crucial to control the bubble expansion. In this study, we investigate the effects of surface microbubbles on the focused jets. Before the impact is performed, the microbubbles are produced on an inner wall of the liquid container by using water-ethanol exchange technique. We experimentally measure the jet velocity and bubble motion utilizing a high-speed camera. It is found that surface microbubbles expand upon the impact, enhancing the increment of jet velocity under the conditions that do not trigger cavitation inception in the bulk liquid. JSPS KAKENHI Grant Numbers 26709007 and 17H01246.

  20. Analysis of polymer surfaces and thin-film coatings with Raman and surface enhanced Raman scattering

    International Nuclear Information System (INIS)

    McAnally, Gerard David

    2001-01-01

    This thesis investigates the potential of surface-enhanced Raman scattering (SERS) for the analysis and characterisation of polymer surfaces. The Raman and SERS spectra from a PET film are presented. The SERS spectra from the related polyester PBT and from the monomer DMT are identical to PET, showing that only the aromatic signals are enhanced. Evidence from other compounds is presented to show that loss of the carbonyl stretch (1725 cm -1 ) from the spectra is due to a chemical interaction between the silver and surface carbonyl groups. The interaction of other polymer functional groups with silver is discussed. A comparison of Raman and SERS spectra collected from three faces of a single crystal shows the SERS spectra are depolarised. AFM images of the silver films used to obtain SERS are presented. They consist of regular islands of silver, fused together to form a complete film. The stability and reproducibility and of these surfaces is assessed. Band assignments for the SERS spectrum of PET are presented. A new band in the spectrum (1131 cm -1 ) is assigned to a complex vibration using a density functional calculation. Depth profiling through a polymer film on to the silver layer showed the SERS signals arise from the silver surface only. The profiles show the effects of refraction on the beam, and the adverse affect on the depth resolution. Silver films were used to obtain SERS spectra from a 40 nm thin-film coating on PET, without interference from the PET layer. The use of an azo dye probe as a marker to detect the coating is described. Finally, a novel method for the synthesis of a SERS-active vinyl-benzotriazole monomer is reported. The monomer was incorporated into a thin-film coating and the SERS spectrum obtained from the polymer. (author)

  1. Enhanced coherence within the theta band between pairs of brains engaging in experienced versus naïve Reiki procedures.

    Science.gov (United States)

    Ventura, Anabela Carraca; Persinger, Michael A

    2014-08-01

    The study objective was to discern whether the coherence between brain activities of the "patient" and practitioner differ between Reiki experts and novices. If the physical process associated with Reiki involves "convergence" between the practitioner and subject, then this congruence should be evident in time-dependent shared power within specific and meaningful frequency electroencephalographic bands. Simultaneous quantitative electroencephalogram measures (19 channels) were recorded from 9 pairs of subjects when 1 of the pairs was an experienced Reiki practitioner or had just been shown the procedure. Pairs recorded their experiences and images. The "practitioner" and "patient" pairs were measured within a quiet, comfortable acoustic chamber. Real-time correlations and coherence between pairs of brains for power (μV(2)·Hz(-1)) within the various frequency bands over the 10-min sessions were recorded and analyzed for each pair. Descriptors of experiences were analyzed for word meanings. Only the coherence within the theta range increased over time between the brains of the Reiki pairs relative to the Sham pairs, particularly over the left hemisphere. The pleasantness-unpleasantness rating for the words employed to describe experiences written after the experiment were more congruent for the Reiki pairs compared to the reference pairs. The increased synchronization of the cerebral activity of the participant and the practitioner during proximal therapies involving touch such as Reiki may be an important component of any subsequent beneficial effects.

  2. Surface- and tip-enhanced Raman scattering of bradykinin onto the colloidal suspended Ag surface.

    Science.gov (United States)

    Swiech, D; Ozaki, Y; Kim, Y; Proniewicz, E

    2015-07-14

    In this paper, surface- (SERS) and tip-enhanced Raman scattering (TERS) techniques were used to determine the adsorption mode of bradykinin (BK), a small peptide implicated in, for example, carcinoma growth, onto colloidal suspended Ag surfaces under various environmental conditions, including: peptide concentrations (10(-5)-10(-7) M), excitation wavelengths (514.5 and 785.0 nm), and pH of aqueous sol solutions (from pH = 3 to pH = 11). The metal surface plasmon and rheology of the colloidal suspended Ag surface were explored by ultraviolet-visible (UV-Vis) spectroscopy and atomic force/scanning electron microscopy (AFM/SEM). The SERS results indicated that the peptide concentration of 10(-5) M was the optimal peptide concentration for monolayer colloidal coverage. The Phe(5/8) and Arg(9) residues of BK generally participated in the interactions with colloidal suspended Ag surfaces. The amide group appeared to be arranged in the same manner to the Ag surface in the pH range of 3 to 11. At acidic pH of the solution (pH = 3 to 5), the BK -COO(-) terminal group binds to the Ag surface as a bidentate (at pH = 3) or monodentate (at pH = 5) chelating ligand. At pH = 11, the imino group of Arg(9), probably due to its -C[double bond, length as m-dash]N(⊕)H2 protonation state, was not involved in the interaction with Ag. The reduction in the solution alkalinity (pH = 9) produced the deprotonation of the -C=N(⊕)H2 group followed by group rearrangement in a way favoring the interaction between the lone electron pair on N and Ag. The TERS studies confirmed the proposed, on the basis of SERS, behavior of BK onto the colloidal suspended Ag at pH = 7 and showed that in different points of the colloidal suspended Ag surface the same peptide fragments approximately having the same orientations with respect to this surface interact with it.

  3. Assessing Telomere Length Using Surface Enhanced Raman Scattering

    Science.gov (United States)

    Zong, Shenfei; Wang, Zhuyuan; Chen, Hui; Cui, Yiping

    2014-11-01

    Telomere length can provide valuable insight into telomeres and telomerase related diseases, including cancer. Here, we present a brand-new optical telomere length measurement protocol using surface enhanced Raman scattering (SERS). In this protocol, two single strand DNA are used as SERS probes. They are labeled with two different Raman molecules and can specifically hybridize with telomeres and centromere, respectively. First, genome DNA is extracted from cells. Then the telomere and centromere SERS probes are added into the genome DNA. After hybridization with genome DNA, excess SERS probes are removed by magnetic capturing nanoparticles. Finally, the genome DNA with SERS probes attached is dropped onto a SERS substrate and subjected to SERS measurement. Longer telomeres result in more attached telomere probes, thus a stronger SERS signal. Consequently, SERS signal can be used as an indicator of telomere length. Centromere is used as the inner control. By calibrating the SERS intensity of telomere probe with that of the centromere probe, SERS based telomere measurement is realized. This protocol does not require polymerase chain reaction (PCR) or electrophoresis procedures, which greatly simplifies the detection process. We anticipate that this easy-operation and cost-effective protocol is a fine alternative for the assessment of telomere length.

  4. Rapid surface enhanced Raman scattering detection method for chloramphenicol residues

    Science.gov (United States)

    Ji, Wei; Yao, Weirong

    2015-06-01

    Chloramphenicol (CAP) is a widely used amide alcohol antibiotics, which has been banned from using in food producing animals in many countries. In this study, surface enhanced Raman scattering (SERS) coupled with gold colloidal nanoparticles was used for the rapid analysis of CAP. Density functional theory (DFT) calculations were conducted with Gaussian 03 at the B3LYP level using the 3-21G(d) and 6-31G(d) basis sets to analyze the assignment of vibrations. Affirmatively, the theoretical Raman spectrum of CAP was in complete agreement with the experimental spectrum. They both exhibited three strong peaks characteristic of CAP at 1104 cm-1, 1344 cm-1, 1596 cm-1, which were used for rapid qualitative analysis of CAP residues in food samples. The use of SERS as a method for the measurements of CAP was explored by comparing use of different solvents, gold colloidal nanoparticles concentration and absorption time. The method of the detection limit was determined as 0.1 μg/mL using optimum conditions. The Raman peak at 1344 cm-1 was used as the index for quantitative analysis of CAP in food samples, with a linear correlation of R2 = 0.9802. Quantitative analysis of CAP residues in foods revealed that the SERS technique with gold colloidal nanoparticles was sensitive and of a good stability and linear correlation, and suited for rapid analysis of CAP residue in a variety of food samples.

  5. Surface-Enhanced Raman Scattering Nanoparticles as Optical Labels for Imaging Cell Surface Proteins

    Science.gov (United States)

    MacLaughlin, Christina M.

    Assaying the expression of cell surface proteins has widespread application for characterizing cell type, developmental stage, and monitoring disease transformation. Immunophenotyping is conducted by treating cells with labelled targeting moieties that have high affinity for relevant surface protein(s). The sensitivity and specificity of immunophenotyping is defined by the choice of contrast agent and therefore, the number of resolvable signals that can be used to simultaneously label cells. Narrow band width surface-enhanced Raman scattering (SERS) nanoparticles are proposed as optical labels for multiplexed immunophenotying. Two types of surface coatings were investigated to passivate the gold nanoparticles, incorporate SERS functionality, and to facilitate attachment of targeting antibodies. Thiolated poly(ethylene glycol) forms dative bonds with the gold surface and is compatible with multiple physisorbed Raman-active reporter molecules. Ternary lipid bilayers are used to encapsulate the gold nanoparticles particles, and incorporate three different classes of Raman reporters. TEM, UV-Visible absorbance spectroscopy, DLS, and electrophoretic light scattering were used characterize the particle coating. Colourimetric protein assay, and secondary antibody labelling were used to quantify the antibody conjugation. Three different in vitromodels were used to investigate the binding efficacy and specificity of SERS labels for their biomarker targets. Primary human CLL cells, LY10 B lymphoma, and A549 adenocarcinoma lines were targeted. Dark field imaging was used to visualize the colocalization of SERS labels with cells, and evidence of receptor clustering was obtained based on colour shifts of the particles' Rayleigh scattering. Widefield, and spatially-resolved Raman spectra were used to detect labels singly, and in combination from labelled cells. Fluorescence flow cytometry was used to test the particles' binding specificity, and SERS from labelled cells was also

  6. Observation of coherently enhanced tunable narrow-band terahertz transition radiation from a relativistic sub-picosecond electron bunch train

    International Nuclear Information System (INIS)

    Piot, P.; Maxwell, T. J.; Sun, Y.-E; Ruan, J.; Lumpkin, A. H.; Thurman-Keup, R.; Rihaoui, M. M.

    2011-01-01

    We experimentally demonstrate the production of narrow-band (δf/f≅20% at f≅0.5THz) transition radiation with tunable frequency over [0.37, 0.86] THz. The radiation is produced as a train of sub-picosecond relativistic electron bunches transits at the vacuum-aluminum interface of an aluminum converter screen. The bunch train is generated via a transverse-to-longitudinal phase space exchange technique. We also show a possible application of modulated beams to extend the dynamical range of a popular bunch length diagnostic technique based on the spectral analysis of coherent radiation.

  7. Reconstruction of surface morphology from coherent scattering of ''white'' synchrotron radiation in hard X-ray regime

    Energy Technology Data Exchange (ETDEWEB)

    Sant, Tushar

    2009-07-01

    Energy Dispersive Reflectometry (EDR) beamline at BESSY II provides ''white'' X-rays in the useful energy range of 5coherent reflectivity data at EDR bending magnet beamline at BESSY II from various surfaces. Technologically smooth wafers of semiconducting materials of Si and GaAs are used as ''trivial'' samples to determine the so called apparatus function. In addition I measured coherent reflectivity maps from thin film of highly scattering material of Pt with high atom number, Z=78 and patterned semiconducting surface like a GaAs surface grating which provides a certain periodicity in the measured scattering intensity. Finally I measured the surface speckles from a spatially confined Si wafer under the constraint that the size of the sample is smaller than the footprint of the incoming beam at the sample position. To reconstruct surface morphology from coherent reflectivity data is a typical inverse problem. Conventional phase retrieval algorithms like Gerchberg-Saxton (GS) algorithm, error reduction (ER) algorithm, hybrid input-output (HIO) algorithm are used in earlier work by other authors. I modified the conventional GS algorithm and ER algorithm which takes into account the additional Fresnel propagator term and also the illumination function at the sample position. I tested the modified algorithm successfully for a model surface in the form of a surface grating. I used the modified algorithm to reconstruct surface morphology from various static speckle measurements I performed at EDR beamline. The surface profiles reconstructed for different samples from the data at different energies (below the critical energy for the material at a particular incident angle) show almost the same roughness behavior for surface height with mean roughness of {proportional_to}1 nm. With the static speckle data I measured I could retrieve a one-dimensional picture of the sample surface with spatial

  8. Pool boiling CHF enhancement by micro/nanoscale modification of zircaloy-4 surface

    International Nuclear Information System (INIS)

    Ahn, Ho Seon; Lee, Chan; Kim, Hyungdae; Jo, HangJin; Kang, SoonHo; Kim, Joonwon; Shin, Jeongseob; Kim, Moo Hwan

    2010-01-01

    Consideration of the critical heat flux (CHF) requires difficult compromises between economy and safety in many types of thermal systems, including nuclear power plants. Much research has been directed towards enhancing the CHF, and many recent studies have revealed that the significant CHF enhancement in nanofluids is due to surface deposition of nanoparticles. The surface deposition of nanoparticles influenced various surface characteristics. This fact indicated that the surface wettability is a key parameter for CHF enhancement and so is the surface morphology. In this study, surface wettability of zircaloy-4 used as cladding material of fuel rods in nuclear power plants was modified using surface treatment technique (i.e. anodization). Pool boiling experiments of distilled water on the prepared surfaces was conducted at atmospheric and saturated conditions to examine effects of the surface modification on CHF. The experimental results showed that CHF of zircaloy-4 can be significantly enhanced by the improvement in surface wettability using the surface modification, but only the wettability effect cannot explain the CHF increase on the treated zircaloy-4 surfaces completely. It was found that below a critical value of contact angle (10 o ), micro/nanostructures created by the surface treatment increased spreadability of liquid on the surface, which could lead to further increase in CHF even beyond the prediction caused only by the wettability improvement. These micro/nanostructures with multiscale on heated surface induced more significant CHF enhancement than it based on the wettability effect, due to liquid spreadability.

  9. A microfluidic surface enhanced Raman spectroscopic biosensor using aptamer functionalized nanopillars

    DEFF Research Database (Denmark)

    Yang, J.; Palla, M.; Bosco, F. G.

    2013-01-01

    This paper presents a microchip incorporating an aptamer-functionalized nanopillar substrate, enabling the specific detection of low-abundance biomolecules using surface enhanced Raman spectroscopy (SERS). In a temperature controlled microchamber, aptamers immobilized on the nanostructure surface...

  10. Localized surface plasmon enhanced cellular imaging using random metallic structures

    Science.gov (United States)

    Son, Taehwang; Lee, Wonju; Kim, Donghyun

    2017-02-01

    We have studied fluorescence cellular imaging with randomly distributed localized near-field induced by silver nano-islands. For the fabrication of nano-islands, a 10-nm silver thin film evaporated on a BK7 glass substrate with an adhesion layer of 2-nm thick chromium. Micrometer sized silver square pattern was defined using e-beam lithography and then the film was annealed at 200°C. Raw images were restored using electric field distribution produced on the surface of random nano-islands. Nano-islands were modeled from SEM images. 488-nm p-polarized light source was set to be incident at 60°. Simulation results show that localized electric fields were created among nano-islands and that their average size was found to be 135 nm. The feasibility was tested using conventional total internal reflection fluorescence microscopy while the angle of incidence was adjusted to maximize field enhancement. Mouse microphage cells were cultured on nano-islands, and actin filaments were selectively stained with FITC-conjugated phalloidin. Acquired images were deconvolved based on linear imaging theory, in which molecular distribution was sampled by randomly distributed localized near-field and blurred by point spread function of far-field optics. The optimum fluorophore distribution was probabilistically estimated by repetitively matching a raw image. The deconvolved images are estimated to have a resolution in the range of 100-150 nm largely determined by the size of localized near-fields. We also discuss and compare the results with images acquired with periodic nano-aperture arrays in various optical configurations to excite localized plasmonic fields and to produce super-resolved molecular images.

  11. Enhanced Modeling of Remotely Sensed Annual Land Surface Temperature Cycle

    Science.gov (United States)

    Zou, Z.; Zhan, W.; Jiang, L.

    2017-09-01

    Satellite thermal remote sensing provides access to acquire large-scale Land surface temperature (LST) data, but also generates missing and abnormal values resulting from non-clear-sky conditions. Given this limitation, Annual Temperature Cycle (ATC) model was employed to reconstruct the continuous daily LST data over a year. The original model ATCO used harmonic functions, but the dramatic changes of the real LST caused by the weather changes remained unclear due to the smooth sine curve. Using Aqua/MODIS LST products, NDVI and meteorological data, we proposed enhanced model ATCE based on ATCO to describe the fluctuation and compared their performances for the Yangtze River Delta region of China. The results demonstrated that, the overall root mean square errors (RMSEs) of the ATCE was lower than ATCO, and the improved accuracy of daytime was better than that of night, with the errors decreased by 0.64 K and 0.36 K, respectively. The improvements of accuracies varied with different land cover types: the forest, grassland and built-up areas improved larger than water. And the spatial heterogeneity was observed for performance of ATC model: the RMSEs of built-up area, forest and grassland were around 3.0 K in the daytime, while the water attained 2.27 K; at night, the accuracies of all types significantly increased to similar RMSEs level about 2 K. By comparing the differences between LSTs simulated by two models in different seasons, it was found that the differences were smaller in the spring and autumn, while larger in the summer and winter.

  12. Detection of Surface-Linked Polychlorinated Biphenyls using Surface-Enhanced Raman Scattering Spectroscopy

    DEFF Research Database (Denmark)

    Rindzevicius, Tomas; Barten, Jan; Vorobiev, Mikhail

    2017-01-01

    We present an improved procedure for analytical detection of toxic polychlorinated biphenyls (PCB) using surface-enhanced Raman scattering (SERS) spectroscopy. A gold-capped silicon nanopillar substrate was utilized to concentrate PCB molecules within an area of high electromagnetic fields through...... formation of microsized nanopillar clusters, and consequently, so-called “hot spots” can be formed. In order to improve PCB detection limit, 3,3',4,4'-tetrachlorobiphenyl (PCB77) compounds were chemically modified with a – SCH3 (PCB77-SCH3) group. Experimental and numerical analysis of vibrational modes...... showed only minor differences between standard PCB77 and PCB77-SCH3. Consequently, we observe significantly increased SERS signals for –SCH3 modified PCB77 while retaining most vibrational modes that characterize standard PCB77. Results point towards more efficient path for detecting different PCB...

  13. Enhanced osteoblast response to electrical discharge machining surface.

    Science.gov (United States)

    Otsuka, Fukunaga; Kataoka, Yu; Miyazaki, Takashi

    2012-01-01

    The purpose of this study is to investigate the surface characteristics and biocompatibility of titanium (Ti) surfaces modified by wire electrical discharge machining (EDM). EDM surface characteristics were evaluated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), thin-film X-ray diffractometry (XRD) and contact angle measurements. MC3T3-E1 cell morphology, attachment and proliferation, as well as analysis of osteoblastic gene expressions, on machined surfaces and EDM surfaces were also evaluated. EDM surfaces exhibited high super hydrophilicity, due to high surface energy. XPS and XRD revealed that a passive oxide layer with certain developing thickness onto. EDM surfaces promoted cell attachment, but restrained proliferation. Counted cell numbers increased significantly on the machined surfaces as compared to the EDM surfaces. Real-time PCR analyses showed significantly higher relative mRNA expression levels of osteoblastic genes (ALP, osteocalcin, Runx2, Osterix) in cells cultured on the EDM surfaces as compared to cells cultured on the machined surfaces.

  14. Enhanced Fluorescence from Fluorophores on Fractal Silver Surfaces

    OpenAIRE

    Parfenov, Alexandr; Gryczynski, Ignacy; Malicka, Joanna; Geddes, Chris D.; Lakowicz, Joseph R.

    2003-01-01

    Recent reports have shown enhanced fluorescence for fluorophores in close proximity to chemically deposited silver islands or colloids. To expand the usefulness of metal-enhanced fluorescence we tested fractal silver structures formed on, or near, silver electrodes by passage of electric currents. The emission intensity of fluorescein-labeled human serum albumin (FITC-HSA) was enhanced over 100-fold when adsorbed to the fractal silver structures as compared to glass. The amplitude-weighted li...

  15. Amplification of Surface-Enhanced Raman Scattering Due to Substrate-Mediated Localized Surface Plasmons in Gold Nanodimers

    KAUST Repository

    Yue, Weisheng

    2017-03-28

    Surface-enhanced Raman scattering (SERS) is ubiquitous in chemical and biochemical sensing, imaging and identification. Maximizing SERS enhancement is a continuous effort focused on the design of appropriate SERS substrates. Here we show that significant improvement in a SERS signal can be achieved with substrates combining localized surface plasmon resonances and a nonresonant plasmonic substrate. By introducing a continuous gold (Au) film underneath Au nanodimers antenna arrays, an over 10-fold increase in SERS enhancement is demonstrated. Triangular, rectangle and disc dimers were studied, with bowtie antenna providing highest SERS enhancement. Simulations of electromagnetic field distributions of the Au nanodimers on the Au film support the observed enhancement dependences. The hybridization of localized plasmonic modes with the image modes in a metal film provides a straightforward way to improve SERS enhancement in designer SERS substrate.

  16. Silver endotaxy in silicon under various ambient conditions and their use as surface enhanced Raman spectroscopy substrates

    International Nuclear Information System (INIS)

    Juluri, R.R.; Ghosh, A.; Bhukta, A.; Sathyavathi, R.; Satyam, P.V.

    2015-01-01

    Search for reliable, robust and efficient substrates for surface enhanced Raman spectroscopy (SERS) leads to the growth of various shapes and nanostructures of noble metals, and in particular, Ag nanostructures for this purpose. Coherently embedded (also known as endotaxial) Ag nanostructures in silicon substrates can be made robust and reusable SERS substrates. In this paper, we show the possibility of the growth of Ag endotaxial structures in Si crystal during Ar and low-vacuum annealing conditions while this is absent in O 2 and ultra high vacuum (UHV) annealing conditions and along with their respective use as SERS substrates. Systems annealed under air-annealing and low-vacuum conditions were found to show larger enhancement factors (typically ≈ 5 × 10 5 in SERS measurement for 0.5 nM Crystal Violet (CV) molecule) while the systems prepared under UHV-annealing conditions (where no endotaxial Ag structures were formed) were found to be not effective as SERS substrates. Extensive electron microscopy, synchrotron X-ray diffraction and Rutherford backscattering spectrometry techniques were used to understand the structural aspects. - Highlights: • Various aspects on the growth of endotaxial Ag nanostructures are presented. • Optimum amount of oxygen is necessary for the growth of endotaxial structures. • Reaction of oxygen with GeOx and SiOx plays a crucial role. • Ag nanostructures prepared under UHV conditions show low SERS activity • SERS enhancement is better for low-vacuum and argon annealing conditions

  17. Role of Electronic-Vibrational Mixing in Enhancing Vibrational Coherences in the Ground Electronic States of Photosynthetic Bacterial Reaction Center

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, Ian Seungwan [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Physical Bioscience Division; Dong, Hui [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Physical Bioscience Division; Fleming, Graham R. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Physical Bioscience Division

    2014-01-24

    Described is the polarization controlled two-color coherence photon echo studies of the reaction center complex from a purple bacterium Rhodobacter sphaeroides. Long-lived oscillatory signals that persist up to 2 ps are observed in neutral, oxidized, and mutant (lacking the special pair) reaction centers, for both (0,0,0,0) and (45,-45,90,0) polarization sequences. We show that the long-lived signals arise via vibronic coupling of the bacteriopheophytin (H) and accessory bacteriochlorophyll (B) pigments that leads to vibrational wavepackets in the B ground electronic state. Fourier analysis of the data suggests that the 685 cm-1 mode of B may play a key role in the H to B energy transfer.

  18. Coherence matrix of plasmonic beams

    DEFF Research Database (Denmark)

    Novitsky, Andrey; Lavrinenko, Andrei

    2013-01-01

    We consider monochromatic electromagnetic beams of surface plasmon-polaritons created at interfaces between dielectric media and metals. We theoretically study non-coherent superpositions of elementary surface waves and discuss their spectral degree of polarization, Stokes parameters, and the for...... of the spectral coherence matrix. We compare the polarization properties of the surface plasmonspolaritons as three-dimensional and two-dimensional fields concluding that the latter is superior....

  19. Enhancement of endothelialisation of coronary stents by laser surface engineering.

    Science.gov (United States)

    Li, Lin; Mirhosseini, Nazanin; Michael, Alun; Liu, Zhu; Wang, Tao

    2013-11-01

    Coronary stents have been widely used in the treatment of coronary heart disease. However, complications have hampered the long-term success of the device. Bare-metal stents (BMS) have a high rate of restenosis and poor endothelialisation. The drug-eluting stents (DES), although dramatically reduce restenosis, significantly prevent endothelialisation leading to late thrombosis and behave the same way as BMS after drug releasing. Rapid adhesion and growth of endothelial cells on the stent surface is a key process for early vascular healing after coronary stenting which contributes to the reduction of major complications. Surface properties manipulate cell growth and directly determine the success and life-span of the implants. However, the ideal surface properties of coronary stents are not yet fully understood. The objective of this research is to understand how surface micro/nano textures and associated material chemistry changes generated by a laser beam affect the behavior of endothelial cells on bare metal 316L stents. A high power laser beam was applied to modifying the surface properties of 316L coronary stent material and the commercial coronary stents, followed by examination of the adhesion and proliferation of human coronary endothelial cells that were growing on the surfaces. Surface properties were examined by scanning electron microscopy, contact angle measurement, and X-ray photoelectron spectroscopy. A novel surface with combined micro/nano features was created on stent material 316L and coronary stent with a specific surface chemistry. This surface gives rise to a threefold increase in the adhesion and eightfold increase in the proliferation of endothelial cells. Interestingly, such effects were only observed when the surface texture was produced in the nitrogen atmosphere suggesting the importance of the surface chemistry, including the dramatic increase of chromium nitride, for the interaction of endothelial cells with the material surface. This

  20. Novel Chiroptical Analysis of Hemoglobin by Surface Enhanced Resonance Raman Optical Activity Spectroscopy

    DEFF Research Database (Denmark)

    Brazhe, Nadezda; Brazhe, Alexey; Sosnovtseva, Olga

    2010-01-01

    The metalloprotein hemoglobin (Hb) was studied using surface enhanced resonance Raman spectroscopy (SERRS) and surface enhanced resonance Raman optical activity (SERROA). The SERROA results are analyzed and compared with the SERRS, and the later to the resonance Raman (RRS) performed on Hb...

  1. Gold nanolenses generated by laser ablation-efficient enhancing structure for surface enhanced Raman scattering analytics and sensing.

    Science.gov (United States)

    Kneipp, Janina; Li, Xiangting; Sherwood, Margaret; Panne, Ulrich; Kneipp, Harald; Stockman, Mark I; Kneipp, Katrin

    2008-06-01

    Nanoaggregates formed by metal spheres of different radii and interparticle distances represent finite, deterministic, self-similar systems that efficiently concentrate optical fields and act as "nanolenses". Here we verify experimentally the theoretical concept of nanolenses and explore their potential as enhancing nanostructures in surface enhanced Raman scattering (SERS). Self-similar structures formed by gold nanospheres of different sizes are generated by laser ablation from solid gold into water. These nanolenses exhibit SERS enhancement factors on the order of 10(9). The "chemically clean" preparation process provides several advantages over chemically prepared nanoaggregates and makes the stable and biocompatible gold nanolenses potent enhancing structures for various analytical and sensing applications.

  2. Large-area electromagnetic enhancement by a resonant excitation of surface waves on a metallic surface with periodic subwavelength patterns.

    Science.gov (United States)

    Zhang, Xin; Liu, Haitao; Zhong, Ying

    2013-10-07

    We theoretically investigate the electromagnetic enhancement on a metallic surface patterned with periodic subwavelength structures. Fully-vectorial calculations show a large-area electromagnetic enhancement (LAEE) on the surface, which strongly contrasts with the previously reported "hot spots" that occur in specific tiny regions and which relieves the rigorous requirement of the nano-scale location of sample molecules. The LAEE allows for designing more practicable substrates for many enhanced-spectra applications. By building up microscopic models, the LAEE is shown due to a resonant excitation of surface waves that include both the surface plasmon polariton (SPP) and a quasi-cylindrical wave (QCW). The surface waves propagate on the substrate over a long distance and thus greatly enlarge the area of electromagnetic enhancement compared to the nano-sized hot spots caused by localized modes. Gain medium is introduced to further strengthen the large-area surface-wave resonance, with which an enhancement factor (EF) of electric-field intensity up to a few thousands is achieved.

  3. Surface wettability of silicon substrates enhanced by laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Tseng, Shih-Feng [National Applied Research Laboratories, Instrument Technology Research Center, Hsinchu (China); National Chiao Tung University, Department of Mechanical Engineering, Hsinchu (China); Hsiao, Wen-Tse; Huang, Kuo-Cheng; Hsiao, Sheng-Yi [National Applied Research Laboratories, Instrument Technology Research Center, Hsinchu (China); Chen, Ming-Fei [National Changhua University of Education, Department of Mechatronics Engineering, Changhua (China); Lin, Yung-Sheng [Hungkuang University, Department of Applied Cosmetology and Graduate Institute of Cosmetic Science, Taichung (China); Chou, Chang-Pin [National Chiao Tung University, Department of Mechanical Engineering, Hsinchu (China)

    2010-11-15

    Laser-ablation techniques have been widely applied for removing material from a solid surface using a laser-beam irradiating apparatus. This paper presents a surface-texturing technique to create rough patterns on a silicon substrate using a pulsed Nd:YAG laser system. The different degrees of microstructure and surface roughness were adjusted by the laser fluence and laser pulse duration. A scanning electron microscope (SEM) and a 3D confocal laser-scanning microscope are used to measure the surface micrograph and roughness of the patterns, respectively. The contact angle variations between droplets on the textured surface were measured using an FTA 188 video contact angle analyzer. The results indicate that increasing the values of laser fluence and laser pulse duration pushes more molten slag piled around these patterns to create micro-sized craters and leads to an increase in the crater height and surface roughness. A typical example of a droplet on a laser-textured surface shows that the droplet spreads very quickly and almost disappears within 0.5167 s, compared to a contact angle of 47.9 on an untextured surface. This processing technique can also be applied to fabricating Si solar panels to increase the absorption efficiency of light. (orig.)

  4. Enhancement of surface magnetism due to bulk bond dilution

    International Nuclear Information System (INIS)

    Tsallis, C.; Sarmento, E.F.; Albuquerque, E.L. de

    1985-01-01

    Within a renormalization group scheme, the phase diagram of a semi-infinite simple cubic Ising ferromagnet is discussed, with arbitrary surface and bulk coupling constants, and including possible dilution of the bulk bonds. It is obtained that dilution makes easier the appearance of surface magnetism in the absence of bulk magnetism. (Author) [pt

  5. Enhanced quantum efficiency of photoelectron emission, through surface textured metal electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, Anna; Bandaru, Prabhakar R., E-mail: pbandaru@ucsd.edu [Program in Materials Science, Department of Mechanical Engineering, University of California, San Diego, La Jolla, California, 92130 (United States); Moody, Nathan A. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2016-03-15

    It is predicted that the quantum efficiency (QE) of photoelectron emission from metals may be enhanced, possibly by an order of magnitude, through optimized surface texture. Through extensive computational simulations, it is shown that the absorption enhancement in select surface groove geometries may be a dominant contributor to enhanced QE and corresponds to localized Fabry–Perot resonances. The inadequacy of extant analytical models in predicting the QE increase, and suggestions for further improvement, are discussed.

  6. A supportive family environment in childhood enhances the level and heritability of sense of coherence in early adulthood.

    Science.gov (United States)

    Silventoinen, Karri; Volanen, Salla-Maarit; Vuoksimaa, Eero; Rose, Richard J; Suominen, Sakari; Kaprio, Jaakko

    2014-12-01

    To analyze the effects of genetic and environmental factors on sense of coherence (SOC) in young adulthood and whether family environment measured in childhood modifies these effects. SOC was measured at 20-27 years of age in 3,193 Finnish twins using the Antonovsky's 13-item short scale. The twins and their parents had rated their emotional family environment independently when the twins were 12 years of age. The data were analyzed using applications of structural linear equation modeling to twin data. Females rated SOC 2.42 points lower than males. Additive genetic factors explained 39% of the variation of SOC in males and 49% in females, whereas the rest of the variation was explained by environmental factors unique to each twin individual. For the dimensions of SOC, the highest genetic correlation was found between comprehensibility and manageability (0.90 in males and 0.97 in females). SOC was strongest in the participants who had reported supportive family atmosphere and low relational tensions to parents in childhood. These participants also had higher genetic variance and lower unique environmental variance of SOC when compared to those who reported emotionally more stressful family environment. The results were similar when we used parental rating of family environment. Genetic factors are important for SOC, but genetic influences are much greater in supportive family environments. This emphasizes the importance of childhood home for the development of strong SOC.

  7. Enhancement of surface properties for coal beneficiation. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Chander, S.; Aplan, F.F.

    1992-01-30

    This report will focus on means of pyrite removal from coal using surface-based coal cleaning technologies. The major subjects being addressed in this study are the natural and modulated surface properties of coal and pyrite and how they may best be utilized to facilitate their separation using advanced surface-based coal cleaning technology. Emphasis is based on modified flotation and oil agglomerative processes and the basic principles involved. The four areas being addressed are: (1) Collectorless flotation of pyrite; (2) Modulation of pyrite and coal hydrophobicity; (3) Emulsion processes and principles; (4) Evaluation of coal hydrophobicity.

  8. Multi-layer enhancement to polysilicon surface-micromachining technology

    Energy Technology Data Exchange (ETDEWEB)

    Sniegowski, J.J.; Rodgers, M.S. [Sandia National Labs., Albuquerque, NM (United States). Intelligent Micromachine Dept.

    1997-10-01

    A multi-level polysilicon surface-micromachining technology consisting of 5 layers of polysilicon is presented. Surface topography and film mechanical stress are the major impediments encountered in the development of a multilayer surface-micromachining process. However, excellent mechanical film characteristics have been obtained through the use of chemical-mechanical polishing for planarization of topography and by proper sequencing of film deposition with thermal anneals. Examples of operating microactuators, geared power-transfer mechanisms, and optical elements demonstrate the mechanical advantages of construction with 5 polysilicon layers.

  9. Hierarchical surfaces for enhanced self-cleaning applications

    Science.gov (United States)

    Fernández, Ariadna; Francone, Achille; Thamdrup, Lasse H.; Johansson, Alicia; Bilenberg, Brian; Nielsen, Theodor; Guttmann, Markus; Sotomayor Torres, Clivia M.; Kehagias, Nikolaos

    2017-04-01

    In this study we present a flexible and adaptable fabrication method to create complex hierarchical structures over inherently hydrophobic resist materials. We have tested these surfaces for their superhydrophobic behaviour and successfully verified their self-cleaning properties. The followed approach allow us to design and produce superhydrophobic surfaces in a reproducible manner. We have analysed different combination of hierarchical micro-nanostructures for their application to self-cleaning surfaces. A static contact angle value of 170° with a hysteresis of 4° was achieved without the need of any additional chemical treatment on the fabricated hierarchical structures. Dynamic effects were analysed on these surfaces, obtaining a remarkable self-cleaning effect as well as a good robustness over impacting droplets.

  10. Modification of Material Surface Using Plasma-Enhanced Ion Beams

    National Research Council Canada - National Science Library

    Bystritskii, V

    1998-01-01

    ...) Technology for Materials Surface Modification. Following second year programmatic plan, formulated in the conclusion of the 1-st year report we focused our effort on study of aluminum alloys modification (Al2024, 6061, 7075...

  11. Surface plasmon field enhancements in deterministic aperiodic structures.

    Science.gov (United States)

    Shugayev, Roman

    2010-11-22

    In this paper we analyze optical properties and plasmonic field enhancements in large aperiodic nanostructures. We introduce extension of Generalized Ohm's Law approach to estimate electromagnetic properties of Fibonacci, Rudin-Shapiro, cluster-cluster aggregate and random deterministic clusters. Our results suggest that deterministic aperiodic structures produce field enhancements comparable to random morphologies while offering better understanding of field localizations and improved substrate design controllability. Generalized Ohm's law results for deterministic aperiodic structures are in good agreement with simulations obtained using discrete dipole method.

  12. Long reach and enhanced power budget DWDM radio-over-fibre link supported by Raman amplification and coherent detection

    DEFF Research Database (Denmark)

    Caballero Jambrina, Antonio; Guerrero Gonzalez, Neil; Fernandez, Amaya

    2009-01-01

    We report on a scalable and enhanced power budget radio-over-fibre system for hybrid-wireless access networks operating at 12.5 GHz DWDM spacing for 5 GHz RF carriers over a 60 km fibre link with Raman amplification.......We report on a scalable and enhanced power budget radio-over-fibre system for hybrid-wireless access networks operating at 12.5 GHz DWDM spacing for 5 GHz RF carriers over a 60 km fibre link with Raman amplification....

  13. Treatability of South African surface waters by enhanced coagulation

    African Journals Online (AJOL)

    2013-06-05

    Jun 5, 2013 ... standard, many South African water treatment managers may need to consider adoption of enhanced coagulation (EC) in the near future to achieve both turbidity and NOM removal. From the study of 4 South African inland waters, this paper demonstrates that UV254 absorbance provides a more accessible ...

  14. Enhanced Detection of Human Plasma Proteins on Nanostructured Silver Surfaces

    Directory of Open Access Journals (Sweden)

    Zuzana Orságová Králová

    2013-08-01

    enhancement factor of 3.6×102 was achieved for a band with a Raman shift of 2104cm‐1 for globulin deposited onto silver nanostructured film on unpolished stainless steel substrate. The detection limit was 400g/mL. Plasma or serum could present a preferable material for non‐ invasive cancer disease diagnosis using the SERS method.

  15. Enhancement of Polymer Cytocompatibility by Nanostructuring of Polymer Surface

    Directory of Open Access Journals (Sweden)

    Petr Slepička

    2012-01-01

    Full Text Available Polymers with their advantageous physical, chemical, mechanical, and electrical properties and easy manufacturing are widely used in biology, tissue engineering, and medicine, for example, as prosthetic materials. In some cases the polymer usage may be impeded by low biocompatibility of common synthetic polymers. The biocompatibility can be improved by modification of polymer surface, for example, by plasma discharge, irradiation with ionizing radiation, and sometime subsequent grafting with suitable organic (e.g., amino-acids or inorganic (e.g., gold nanoparticles agents. In this way new chemically active structures are created on the polymer surface, and in some cases new surface relief is created. Recent advances in nanotechnology and in characterization of nanostructured objects open the way to development of new polymer-based materials with better bio-properties and higher application potential in biomedicine. Some of recent results obtained in the field are summarized and discussed in this paper.

  16. Biomolecular modification of zirconia surfaces for enhanced biocompatibility

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Shih-Kuang; Hsu, Hsueh-Chuan [Department of Dental Technology and Materials Science, Central Taiwan University of Science and Technology, Taichung 40601, Taiwan, ROC (China); Ho, Wen-Fu [Department of Chemical and Materials Engineering, National University of Kaohsiung, Taiwan, ROC (China); Yao, Chun-Hsu [Department of Biomedical Imaging and Radiological Science, China Medical University, Taichung 40402, Taiwan, ROC (China); Chang, Pai-Ling [Taoyuan General Hospital, Taoyuan 33004, Taiwan, ROC (China); Wu, Shih-Ching, E-mail: scwu@ctust.edu.tw [Department of Dental Technology and Materials Science, Central Taiwan University of Science and Technology, Taichung 40601, Taiwan, ROC (China)

    2014-12-01

    Yttria-tetragonal zirconia polycrystal (Y-TZP) is a preferred biomaterial due to its good mechanical properties. In order to improve the biocompatibility of zirconia, RGD-peptide derived from extracellular matrix proteins was employed to modify the surface of Y-TZP to promote cell adhesion in this study. The surface of Y-TZP specimens was first modified using a hydrothermal method for different lengths of time. The topographies of modified Y-TZP specimens were analyzed by contact angle, XRD, FTIR, AFM, and FE-SEM. The mechanical properties were evaluated using Vickers hardness and three point bending strength. Then, the RGD-peptide was immobilized on the surface of the Y-TZP by chemical treatment. These RGD-peptide immobilized Y-TZP specimens were characterized by FTIR and AFM, and then were cocultured with MG-63 osteoblast cells for biocompatibility assay. The cell morphology and proliferation were evaluated by SEM, WST-1, and ALP activity assay. The XRD results indicated that the phase transition, from tetragonal phase to monoclinic phase, was increased with a longer incubation time of hydrothermal treatment. However, there were no significant differences in mechanical strengths after RGD-peptide was successfully grafted onto the Y-TZP surface. The SEM images showed that the MG-63 cells appeared polygonal, spindle-shaped, and attached on the RGD-peptide immobilized Y-TZP. The proliferation and cellular activities of MG-63 cells on the RGD-peptide immobilized Y-TZP were better than that on the unmodified Y-TZP. From the above results, the RGD-peptide can be successfully grafted onto the hydrothermal modified Y-TZP surface. The RGD-peptide immobilized Y-TZP can increase cell adhesion, and thus, improve the biocompatibility of Y-TZP. - Highlights: • Covalent bonding between peptide and Y-TZP was proposed. • Stable biomimetic structures produced on the surface of zirconia. • The biocompatibility was improved.

  17. Surface-enhanced Raman scattering spectra of adsorbates on Cu₂O nanospheres: charge-transfer and electromagnetic enhancement.

    Science.gov (United States)

    Jiang, Li; You, Tingting; Yin, Penggang; Shang, Yang; Zhang, Dongfeng; Guo, Lin; Yang, Shihe

    2013-04-07

    Surface-enhanced Raman scattering (SERS) spectra of 4-mercaptobenzoic acid (4-MBA) have been investigated on the surface of Cu2O nanospheres. The SERS signals were believed to originate from the static chemical enhancement, resonant chemical enhancement and electromagnetic enhancement. The coupling between the adsorbates and the semiconductor, evidenced by the shift in absorption spectrum of modified Cu2O and the enhancement of non-totally symmetric modes of the 4-MBA and 4-mercaptopyridine (4-MPY) molecules, were invoked to explain the experimental results. Furthermore, simulations were employed to investigate the nature of the enhancement mechanisms operative between the molecules and the semiconductor. Density functional theory (DFT) calculations suggested a charge transfer (CT) transition process between the molecules and the Cu2O nanospheres. Three-dimensional finite-difference time domain (3D-FDTD) simulations were conducted to map out the electromagnetic field around the Cu2O nanospheres. The experimental and simulation results have revealed the promise of the Cu2O nanospheres as a good SERS substrate and the prospect of using the SERS substrate as a valuable tool for in situ investigation and assay of the adsorption behavior on semiconductor surfaces.

  18. Enhanced extraction efficiency of fluorescent SiC by surface nanostructuring

    DEFF Research Database (Denmark)

    Ou, Yiyu; Jokubavicius, Valdas; Yakimova, Rositza

    2012-01-01

    Antireflective structures were fabricated on fluorescent 6H-SiC for white LEDs to enhance the extraction efficiency. Average surface reflectance decreased from 22.1% to 5.1% over a broad range, and luminescence intensity was enhanced by 41%.......Antireflective structures were fabricated on fluorescent 6H-SiC for white LEDs to enhance the extraction efficiency. Average surface reflectance decreased from 22.1% to 5.1% over a broad range, and luminescence intensity was enhanced by 41%....

  19. Design methodology to enhance high impedance surfaces performances

    Directory of Open Access Journals (Sweden)

    M. Grelier

    2014-04-01

    Full Text Available A methodology is introduced for designing wideband, compact and ultra-thin high impedance surfaces (HIS. A parametric study is carried out to examine the effect of the periodicity on the electromagnetic properties of an HIS. This approach allows designers to reach the best trade-off for HIS performances.

  20. Enhancement of Polymer Cytocompatibility by Nanostructuring of Polymer Surface

    Czech Academy of Sciences Publication Activity Database

    Slepička, P.; Kasálková-Slepičková, N.; Bačáková, Lucie; Kolská, Z.; Švorčík, V.

    2012-01-01

    Roč. 2012, č. 2012 (2012), ID527403 ISSN 1687-4110 R&D Projects: GA ČR(CZ) GBP108/12/G108 Institutional support: RVO:67985823 Keywords : polymer cytocompatibility * polymer surface * nanotechnology Subject RIV: EI - Biotechnology ; Bionics Impact factor: 1.547, year: 2012

  1. Treatability of South African surface waters by enhanced coagulation

    African Journals Online (AJOL)

    The majority of South African inland surface water sources are compromised due to a long-standing national policy of mandatory return flows. With renewed emphasis on the removal of organic carbon in the latest SANS 241 water quality standard, many South African water treatment managers may need to consider ...

  2. Surface enhanced Raman spectra of the organic nonlinear optic ...

    Indian Academy of Sciences (India)

    Wintec

    Institute of Chemistry, University of Opole, Olesksa 48 45-052 Opole, Poland. 1. Present Address: Department of ... The surface geometry of methyl 3-(4-methoxy phenyl)prop-2-enoate molecule was studied by analysis of the SERS spectra .... Harmonic vibrational wave numbers were calculated using analytic second de-.

  3. Surface plasmon resonance optical cavity enhanced refractive index sensing

    Czech Academy of Sciences Publication Activity Database

    Giorgini, A.; Avino, S.; Malara, P.; Gagliardi, G.; Casalino, M.; Coppola, G.; Iodice, M.; Adam, Pavel; Chadt, Karel; Homola, Jiří; De Natale, P.

    2013-01-01

    Roč. 38, č. 11 (2013), s. 1951-1953 ISSN 0146-9592 R&D Projects: GA ČR GBP205/12/G118 Institutional support: RVO:67985882 Keywords : Resonators * Surface plasmons * Optical sensing and sensors Subject RIV: BH - Optics, Masers, Lasers Impact factor: 3.179, year: 2013

  4. Biphilic Surfaces for Enhanced Water Collection from Humid Air

    Science.gov (United States)

    Benkoski, Jason; Gerasopoulos, Konstantinos; Luedeman, William

    Surface wettability plays an important role in water recovery, distillation, dehumidification, and heat transfer. The efficiency of each process depends on the rate of droplet nucleation, droplet growth, and mass transfer. Unfortunately, hydrophilic surfaces are good at nucleation but poor at shedding. Hydrophobic surfaces are the reverse. Many plants and animals overcome this tradeoff through biphilic surfaces with patterned wettability. For example, the Stenocara beetle uses hydrophilic patches on a superhydrophobic background to collect fog from air. Cribellate spiders similarly collect fog on their webs through periodic spindle-knot structures. In this study, we investigate the effects of wettability patterns on the rate of water collection from humid air. The steady state rate of water collection per unit area is measured as a function of undercooling, angle of inclination, water contact angle, hydrophilic patch size, patch spacing, area fraction, and patch height relative to the hydrophobic background. We then model each pattern by comparing the potential and kinetic energy of a droplet as it rolls downwards at a fixed angle. The results indicate that the design rules for collecting fog differ from those for condensation from humid air. The authors gratefully acknowledge the Office of Naval Research for financial support through Grant Number N00014-15-1-2107.

  5. Enhancing the chroma of pigmented polymers using antireflective surface structures

    DEFF Research Database (Denmark)

    Clausen, Jeppe Sandvik; Christiansen, Alexander Bruun; Kristensen, Anders

    2013-01-01

    In this paper we investigate how the color of a pigmented polymer is affected by reduction of the reflectance at the air-polymer interface. Both theoretical and experimental investigations show modified diffuse-direct reflectance spectra when the reflectance of the surface is lowered. Specifically...

  6. Optical Interferometry with Flexible Coherent Fiber Bundle for Measuring Deposits or Contamination on Surfaces and Inside Tubes

    Data.gov (United States)

    National Aeronautics and Space Administration — A new measuring/cleaning method for closed surfaces (pipes) applicable to removing contaminants (oil films, fungus, rust) from NASA instruments and spacecraft is...

  7. Coherent Smith-Purcell radiation as a diagnostic for sub-picosecond electron bunch length

    International Nuclear Information System (INIS)

    Nguyen, D.C.

    1996-01-01

    We suggest a novel technique of measuring sub-picosecond electron bunch length base on coherent Smith-Purcell radiation (SPR) emitted when electrons pass close to the surface of a metal grating. With electron bunch lengths comparable to the grating period, we predict that coherent SPR will be emitted at large angles with respect to direction of beam propagation. As the bunch length shortens, the coherent SPR will be enhanced over the incoherent component that is normally observed at small angles. Furthermore, the angular distribution of the coherent SPR will be shifted toward smaller angles as the bunch length becomes much smaller than the grating period. By measuring the angular distribution of the coherent SPR, one can determine the bunch length of sub-picosecond electron pulses. This new technique is easy to implement and appears capable of measuring femtosecond electron bunch lengths

  8. Application of Anodization Process for Cast Aluminium Surface Properties Enhancement

    Directory of Open Access Journals (Sweden)

    Włodarczyk-Fligier A.

    2016-09-01

    Full Text Available An huge interest is observed in last years in metal matrix composite, mostly light metal based, which have found their applications in many industry branches, among others in the aircraft industry, automotive-, and armaments ones, as well as in electrical engineering and electronics, where one of the most important issue is related to the corrosion resistance, especially on the surface layer of the used aluminium alloys. This elaboration presents the influence of ceramic phase on the corrosion resistance, quality of the surface layer its thickness and structure of an anodic layer formed on aluminium alloys. As test materials it was applied the aluminium alloys Al-Si-Cu and Al-Cu-Mg, for which heat treatment processes and corrosion tests were carried out. It was presented herein grindability test results and metallographic examination, as well. Hardness of the treated alloys with those ones subjected to corrosion process were compared.

  9. Membranes with Surface-Enhanced Antifouling Properties for Water Purification

    Science.gov (United States)

    Shahkaramipour, Nima; Tran, Thien N.; Ramanan, Sankara; Lin, Haiqing

    2017-01-01

    Membrane technology has emerged as an attractive approach for water purification, while mitigation of fouling is key to lower membrane operating costs. This article reviews various materials with antifouling properties that can be coated or grafted onto the membrane surface to improve the antifouling properties of the membranes and thus, retain high water permeance. These materials can be separated into three categories, hydrophilic materials, such as poly(ethylene glycol), polydopamine and zwitterions, hydrophobic materials, such as fluoropolymers, and amphiphilic materials. The states of water in these materials and the mechanisms for the antifouling properties are discussed. The corresponding approaches to coat or graft these materials on the membrane surface are reviewed, and the materials with promising performance are highlighted. PMID:28273869

  10. Super-virtual Interferometric Separation and Enhancement of Back-scattered Surface Waves

    KAUST Repository

    Guo, Bowen

    2015-08-19

    Back-scattered surface waves can be migrated to detect near-surface reflectors with steep dips. A robust surface-wave migration requires the prior separation of the back-scattered surface-wave events from the data. This separation is often difficult to implement because the back-scattered surface waves are masked by the incident surface waves. We mitigate this problem by using a super-virtual interferometric method to enhance and separate the back-scattered surface waves. The key idea is to calculate the virtual back-scattered surface waves by stacking the resulting virtual correlated and convolved traces associated with the incident and back-scattered waves. Stacking the virtual back-scattered surface waves improves their signal-to-noise ratio and separates the back-scattered surface-waves from the incident field. Both synthetic and field data results validate the robustness of this method.

  11. Enhanced Electron-Phonon Coupling at Metal Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Plummer, Ward E.

    2010-08-04

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

  12. Estimating the Analytical and Surface Enhancement Factors in Surface-Enhanced Raman Scattering (SERS): A Novel Physical Chemistry and Nanotechnology Laboratory Experiment

    Science.gov (United States)

    Pavel, Ioana E.; Alnajjar, Khadijeh S.; Monahan, Jennifer L.; Stahler, Adam; Hunter, Nora E.; Weaver, Kent M.; Baker, Joshua D.; Meyerhoefer, Allie J.; Dolson, David A.

    2012-01-01

    A novel laboratory experiment was successfully implemented for undergraduate and graduate students in physical chemistry and nanotechnology. The main goal of the experiment was to rigorously determine the surface-enhanced Raman scattering (SERS)-based sensing capabilities of colloidal silver nanoparticles (AgNPs). These were quantified by…

  13. Normative data of outer photoreceptor layer thickness obtained by software image enhancing based on Stratus optical coherence tomography images

    DEFF Research Database (Denmark)

    Christensen, U.C.; Krøyer, K.; Thomadsen, Jakob

    2008-01-01

    backscattered light within the outer nuclear layer (ONL) in the fovea was registered and compared with backscattered light within the ONL in the peripheral part of the macula (I-ratio-ONL). Results: The mean RPE-OScomplex thickness in the foveal centre was 77.2 mu m (SD = 3.95). The RPE-OScomplex thickness...... in the superior macula 0.5-3 mm of the centre was significantly increased as compared with the corresponding inferior retina. In healthy subjects, the I-ratio-ONL was 1.06. Conclusions: Contrast-enhanced OCT images enable quantification of outer photoreceptor layer thickness, and normative values may help...

  14. Interfacing capillary electrophoresis and surface-enhanced resonance Raman spectroscopy for the determination of dye compounds

    NARCIS (Netherlands)

    Arraez Roman, D.; Efremov, E.V.; Ariese, F.; Segura Carretero, A.; Gooijer, C.

    2005-01-01

    The at-line coupling of capillary electrophoresis (CE) and surface-enhanced resonance Raman spectroscopy (SERRS) was optimized for the separation and subsequent spectroscopic identification of charged analytes (dye compounds). Raman spectra were recorded following deposition of the electropherogram

  15. Surface enhanced second harmonic generation from macrocycle, catenane, and rotaxane thin films : Experiments and theory

    NARCIS (Netherlands)

    Arfaoui, I.; Bermudez, V.; Bottari, G.; De Nadai, C.; Jalkanen, J.P.; Kajzar, F.; Leigh, D.A.; Lubomska, M.; Mendoza, S.M.; Niziol, J.; Rudolf, Petra; Zerbetto, F.

    2006-01-01

    Surface enhanced second harmonic generation (SE SHG) experiments on molecular structures, macrocycles, catenanes, and rotaxanes, deposited as monolayers and multilayers by vacuum sublimation on silver, are reported. The measurements show that the molecules form ordered thin films, where the highest

  16. Surface enhanced SHG from macrocycle, catenane and rotaxane thin films : experiments and theory.

    NARCIS (Netherlands)

    Arfaoui, I.; Bermudez, V.; De Nadai, C.; Jalkanen, J.-P.; Kajzar, F.; Leigh, D.A.; Lubomska, M.; Mendoza, S.M.; Niziol, J.; Rudolf, Petra; Zerbetto, F.; Grote, JG; Kaino, T; Kajzar, F

    2005-01-01

    Surface enhanced second harmonic generation experiments on supramolecules: macrocycles, catenanes and rotaxanes, monolayers and multilayers deposited by vacuum evaporation on silver layers are reported and described. The measurements show that the molecules are ordered in thin films. The highest

  17. Enhanced Transmission of Light and Matter through Nanoapertures without Assistance of Surface Waves

    OpenAIRE

    Kukhlevsky, S. V.

    2006-01-01

    Subwavelength aperture arrays in thin metal films enable enhanced transmission of light and matter waves [for example, see T.W. Ebbesen et al., Nature (London) 391, 667 (1998) and E. Moreno et al., Phys. Rev. Lett. 95, 170406 (2005)]. The phenomenon relies on resonant excitation of the surface electron or matter waves. We show another mechanism that provides a great transmission enhancement not by coupling to the surface waves but by the interference of diffracted evanescent waves in the far-...

  18. Surface-enhanced Raman spectroscopy on novel black silicon-based nanostructured surfaces

    DEFF Research Database (Denmark)

    Talian, Ivan; Mogensen, Klaus Bo; Orinak, A.

    2009-01-01

    , effects of Ti and Ti/Pt adhesion layers underneath the gold layers on the analytical signal enhancement were tested. An enhancement factor of 7.6 x 10(7) with the excitation laser 785 nm was achieved for the tested analyte, Rhodamine 6G, and non-resonance SER spectra were recorded in a 5 s acquisition...

  19. Enhanced propellant performance via environmentally friendly curable surface coating

    Directory of Open Access Journals (Sweden)

    Thelma Manning

    2017-06-01

    Full Text Available Surface coating of granular propellants is widely used in a multiplicity of propellants for small, medium and large caliber ammunition. All small caliber ball propellants exhibit burning progressivity due to application of effective deterrent coatings. Large perforated propellant grains have also begun utilizing plasticizing and impregnated deterrent coatings with the purpose of increasing charge weights for greater energy and velocity for the projectile. The deterrent coating and impregnation process utilizes volatile organic compounds (VOCs and hazardous air pollutants (HAPs which results in propellants that need to be forced air dried which impacts air quality. Propellants undergo temperature fluctuations during their life. Diffusion coefficients vary exponentially with variations in temperature. A small temperature increase can induce a faster migration, even over a short period of time, which can lead to large deviations in the concentration. This large concentration change in the ammunition becomes a safety or performance liability. The presence of both polymeric deterrents and nitroglycerin(NG in the nitrocellulose matrix and organic solvents leads to higher diffusion rates. This results in continued emissions of VOCs and HAPs. Conventional polymers tend to partition within the propellant matrix. In other words, localized mixing can occur between the polymer and underlying propellant. This is due to solvent induced softening of the polymer vehicle over the propellant grain. In effect this creates a path where migration can occur. Since nitrate esters, like NG, are relatively small, it can exude to the surface and create a highly unstable and dangerous situation for the warfighter. Curable polymers do not suffer from this partitioning due to “melting” because no VOC solvents are present. They remain surface coated. The small scale characterization testing, such as closed bomb testing, small scale sensitivity, thermal stability, and

  20. Fructose-enhanced reduction of bacterial growth on nanorough surfaces

    Directory of Open Access Journals (Sweden)

    Durmus NG

    2012-02-01

    Full Text Available Naside Gozde Durmus1, Erik N Taylor1, Fatih Inci3,4, Kim M Kummer1, Keiko M Tarquinio5, Thomas J Webster1,21School of Engineering, Brown University, Providence, RI, USA; 2Department of Orthopedics, Brown University, Providence, RI, USA; 3Bio-Acoustic-MEMS in Medicine (BAMM Laboratory, Center for Biomedical Engineering, Department of Medicine, Brigham and Women's Hospital, Harvard-MIT Health Sciences and Technology, Harvard Medical School, MA, USA; 4Istanbul Technical University, Molecular Biology-Genetics and Biotechnology Program, Mobgam, Maslak, Istanbul, Turkey; 5Division of Pediatric Critical Care Medicine, Rhode Island Hospital, Providence, RI, USAAbstract: Patients on mechanical ventilators for extended periods of time often face the risk of developing ventilator-associated pneumonia. During the ventilation process, patients incapable of breathing are intubated with polyvinyl chloride (PVC endotracheal tubes (ETTs. PVC ETTs provide surfaces where bacteria can attach and proliferate from the contaminated oropharyngeal space to the sterile bronchoalveolar area. To overcome this problem, ETTs can be coated with antimicrobial agents. However, such coatings may easily delaminate during use. Recently, it has been shown that changes in material topography at the nanometer level can provide antibacterial properties. In addition, some metabolites, such as fructose, have been found to increase the efficiency of antibiotics used to treat Staphylococcus aureus (S. aureus infections. In this study, we combined the antibacterial effect of nanorough ETT topographies with sugar metabolites to decrease bacterial growth and biofilm formation on ETTs. We present for the first time that the presence of fructose on the nanorough surfaces decreases the number of planktonic S. aureus bacteria in the solution and biofilm formation on the surface after 24 hours. We thus envision that this method has the potential to impact the future of surface engineering of

  1. Enhanced surface structuring by ultrafast XUV/NIR dual action

    Czech Academy of Sciences Publication Activity Database

    Jakubczak, Krzysztof; Mocek, Tomáš; Chalupský, Jaromír; Lee, G.H.; Kim, T.K.; Park, S.B.; Nam, Ch. H.; Hájková, Věra; Toufarová, Martina; Juha, Libor; Rus, Bedřich

    2011-01-01

    Roč. 13, č. 5 (2011), s. 1-12 ISSN 1367-2630 R&D Projects: GA AV ČR KAN300100702; GA MŠk(CZ) LC528; GA MŠk LA08024; GA ČR GC202/07/J008 Grant - others:AV ČR(CZ) M100100911 Institutional research plan: CEZ:AV0Z10100523 Keywords : XUV beam * ultrafast NIR laser pulses * high-order harmonics * laser-induced periodic surface structures Subject RIV: BH - Optics, Masers, Lasers Impact factor: 4.177, year: 2011 http://iopscience.iop.org/1367-2630/13/5/053049

  2. Self-referenced directional enhanced Raman scattering using plasmon waveguide resonance for surface and bulk sensing

    Science.gov (United States)

    Wan, Xiu-mei; Gao, Ran; Lu, Dan-feng; Qi, Zhi-mei

    2018-01-01

    Surface plasmon-coupled emission has been widely used in fluorescence imaging, biochemical sensing, and enhanced Raman spectroscopy. A self-referenced directional enhanced Raman scattering for simultaneous detection of surface and bulk effects by using plasmon waveguide resonance (PWR) based surface plasmon-coupled emission has been proposed and experimentally demonstrated. Raman scattering was captured on the prism side in Kretschmann-surface plasmon-coupled emission. The distinct penetration depths (δ) of the evanescent field for the transverse electric (TE) and transverse magnetic (TM) modes result in different detected distances of the Raman signal. The experimental results demonstrate that the self-referenced directional enhanced Raman scattering of the TE and TM modes based on the PWR can detect and distinguish the surface and bulk effects simultaneously, which appears to have potential applications in researches of chemistry, medicine, and biology.

  3. Nanostructure design for surface-enhanced Raman spectroscopy - prospects and limits

    DEFF Research Database (Denmark)

    Xiao, Sanshui; Mortensen, Niels Asger; Jauho, Antti-Pekka

    2008-01-01

    Surface-enhanced Raman spectroscopy (SERS) allows single-molecule detection due to the strong field localization occurring at sharp bends or kinks of the metal-vacuum interface. An important question concerns the limits of the signal enhancement that can be achieved via a judicious design...

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

    Science.gov (United States)

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

    2016-06-01

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

  5. Coherence and Sense of Coherence

    DEFF Research Database (Denmark)

    Dau, Susanne

    2014-01-01

    of coherence is both related to conditional matters as learning environments, structure, clarity and linkage but also preconditioned matters and prerequisites among participants related to experiences and convenience. It is stressed that this calls for continuous assessment and reflections upon these terms...

  6. Enhancing nitrilase production from Fusarium proliferatum using response surface methodology.

    Science.gov (United States)

    Yusuf, Farnaz; Chaubey, Asha; Raina, Arvind; Jamwal, Urmila; Parshad, Rajinder

    2013-12-01

    The individual and interactive effects of three independent variables i.e. carbon source (glucose), nitrogen source (sodium nitrate) and inducer (ϵ-caprolactam) on nitrilase production from Fusarium proliferatum were investigated using design of experiments (DOE) methodology. Response surface methodology (RSM) was followed to generate the process model and to obtain the optimal conditions for maximum nitrilase production. Based on central composite design (CCD) a quadratic model was found to fit the experimental data (pnitrilase activity of 58.3U/g biomass obtained experimentally correlated to the predicted activity which proves the authenticity of the model. Overall 2.24 fold increase in nitrilase activity was achieved as compared to the activity before optimization (26U/g biomass).

  7. Porous surface modified bioactive bone cement for enhanced bone bonding.

    Directory of Open Access Journals (Sweden)

    Qiang He

    Full Text Available Polymethylmethacrylate bone cement cannot provide an adhesive chemical bonding to form a stable cement-bone interface. Bioactive bone cements show bone bonding ability, but their clinical application is limited because bone resorption is observed after implantation. Porous polymethylmethacrylate can be achieved with the addition of carboxymethylcellulose, alginate and gelatin microparticles to promote bone ingrowth, but the mechanical properties are too low to be used in orthopedic applications. Bone ingrowth into cement could decrease the possibility of bone resorption and promote the formation of a stable interface. However, scarce literature is reported on bioactive bone cements that allow bone ingrowth. In this paper, we reported a porous surface modified bioactive bone cement with desired mechanical properties, which could allow for bone ingrowth.The porous surface modified bioactive bone cement was evaluated to determine its handling characteristics, mechanical properties and behavior in a simulated body fluid. The in vitro cellular responses of the samples were also investigated in terms of cell attachment, proliferation, and osteoblastic differentiation. Furthermore, bone ingrowth was examined in a rabbit femoral condyle defect model by using micro-CT imaging and histological analysis. The strength of the implant-bone interface was also investigated by push-out tests.The modified bone cement with a low content of bioactive fillers resulted in proper handling characteristics and adequate mechanical properties, but slightly affected its bioactivity. Moreover, the degree of attachment, proliferation and osteogenic differentiation of preosteoblast cells was also increased. The results of the push-out test revealed that higher interfacial bonding strength was achieved with the modified bone cement because of the formation of the apatite layer and the osseointegration after implantation in the bony defect.Our findings suggested a new bioactive

  8. Surface enhanced Raman spectroscopy: A review of recent applications in forensic science

    Science.gov (United States)

    Fikiet, Marisia A.; Khandasammy, Shelby R.; Mistek, Ewelina; Ahmed, Yasmine; Halámková, Lenka; Bueno, Justin; Lednev, Igor K.

    2018-05-01

    Surface enhanced Raman spectroscopy has many advantages over its parent technique of Raman spectroscopy. Some of these advantages such as increased sensitivity and selectivity and therefore the possibility of small sample sizes and detection of small concentrations are invaluable in the field of forensics. A variety of new SERS surfaces and novel approaches are presented here on a wide range of forensically relevant topics.

  9. Ag coated microneedle based surface enhanced Raman scattering probe for intradermal measurements

    Science.gov (United States)

    Yuen, Clement; Liu, Quan

    2013-06-01

    We propose a silver coated microneedle to detect test molecules, including R6G and glucose, positioned at a depth of more than 700 μm below a skin phantom surface for mimicking intradermal surface-enhanced Raman scattering measurements.

  10. Surface-Enhanced Raman Scattering of the Complexes of Silver with Adenine and dAMP

    NARCIS (Netherlands)

    Otto, Cornelis; Hoeben, F.P.; Hoeben, F.P.; Greve, Jan

    1991-01-01

    The behaviour of adenine and 2'-deoxyadenosine-5'-monophosphate (dAMP) at positive surface potentials of a silver working electrode was investigated using surface-enhanced Raman scattering (SERS). The use of positive potentials in the presence of adenine or dAMP leads to a rapid accumulation of an

  11. Measurement of Non-Linear Internal Waves and Their Interaction with Surface Waves using Coherent Real Aperture Radars

    Science.gov (United States)

    2010-03-08

    angles, J. Geophys. Res., 81(12), 1960- 1964, 1976. Kudryavtsev ,V., D. Akimov, J. Johannessen, and B. Chapron, On radar imaging of current...the generation of internal wave microwave surface signatures include Alpers (1985), Lyzenga and Bennett (1988), Thompson, 1988, and Kudryavtsev et...1999. Kudryavtsev , V., D. Akimov, J. Johannessen, and B. Chapron, On radar imaging of current features: 1. Model and comparison with observations

  12. Optimal Design of Slippery Liquid-Infused Porous Surfaces for Enhanced Condensation of Low Surface Tension Fluids

    Science.gov (United States)

    Preston, Daniel J.; Lu, Zhengmao; Zhao, Yajing; Antao, Dion; Wilke, Kyle; Wang, Evelyn N.

    Vapor condensation is routinely used as an effective means of transferring heat or separating fluids. Dropwise condensation, where discrete droplets form on the condenser surface, exhibits 5 - 7x higher heat transfer performance than filmwise condensation, where the condensate spreads over the surface. However, promoting dropwise condensation of low surface tension fluids is particularly challenging since the typical hydrophobic condenser coatings used to promote dropwise condensation of water (surface tension 73 mN/m) often do not repel fluids with low surface tensions (<30 mN/m). Recent work has indicated that slippery liquid-infused porous surfaces (SLIPS) can promote dropwise condensation of low surface tension fluids by introducing a lubricant immiscible with the condensate into a rough structure on the condenser surface. We developed a detailed model of condensation on SLIPS using the van Oss-Chaudhury-Good theory as a framework to determine the feasibility of any arbitrary solid-lubricant-condensate system, and we validated our model with experimental results. This work enables optimal design of SLIPS for enhanced condensation of low surface tension fluids which promises significant energy savings in applications such as thermal management and power generation.

  13. Plasma Treatment Maintains Surface Energy of the Implant Surface and Enhances Osseointegration

    Directory of Open Access Journals (Sweden)

    Fernando P. S. Guastaldi

    2013-01-01

    Full Text Available The surface energy of the implant surface has an impact on osseointegration. In this study, 2 surfaces: nonwashed resorbable blasting media (NWRBM; control and Ar-based nonthermal plasma 30 days (Plasma 30 days; experimental, were investigated with a focus on the surface energy. The surface energy was characterized by the Owens-Wendt-Rabel-Kaelble method and the chemistry by X-ray photoelectron spectroscopy (XPS. Five adult beagle dogs received 8 implants (n=2 per surface, per tibia. After 2 weeks, the animals were euthanized, and half of the implants (n=20 were removal torqued and the other half were histologically processed (n=20. The bone-to-implant contact (BIC and bone area fraction occupancy (BAFO were evaluated on the histologic sections. The XPS analysis showed peaks of C, Ca, O, and P for the control and experimental surfaces. While no significant difference was observed for BIC parameter (P>0.75, a higher level for torque (P<0.02 and BAFO parameter (P<0.01 was observed for the experimental group. The surface elemental chemistry was modified by the plasma and lasted for 30 days after treatment resulting in improved biomechanical fixation and bone formation at 2 weeks compared to the control group.

  14. Adhesion enhancement of Al coatings on carbon/epoxy composite surfaces by atmospheric plasma

    International Nuclear Information System (INIS)

    Coulon, J.F.; Tournerie, N.; Maillard, H.

    2013-01-01

    Adhesion strengths between aluminium thin film coatings and manufactured carbon/epoxy composite surfaces were measured by assessing fracture tensile strengths using pull-off tests. The effect of the substrate roughness (nm to μm) of these composite surfaces on adhesion was studied by examining the surface free energies and adhesion strengths. The adhesion strengths of the coatings varied significantly. To improve the coating adhesion, each composite surface was treated with atmospheric plasma prior to deposition, which resulted in an increase in the surface free energy from approximately 40 mJ/m 2 to 70 mJ/m 2 because the plasma pretreatment led to the formation of hydrophilic C-O and C=O bonds on the composite surfaces, as demonstrated by X-ray photoelectron spectroscopy analyses. The adhesion strengths of the coatings were enhanced for all surface roughnesses studied. In our study, the effect of mechanical adhesion due to roughness was separated from the effect of modifying the chemical bonds with plasma activation. The adhesion ability of the pure resin was relatively weak. Increasing the surface roughness largely improved the adhesion of the resin surface. Plasma treatment of the pure resin also increased the surface adhesion. Our study shows that plasma activation effectively enhances the adhesion of manufactured composites, even when the surface roughness is on the order of microns. The ageing of the surface activation was also investigated, and the results demonstrate that atmospheric plasma has potential for use in the pretreatment of composite materials.

  15. Choroidal thickness in fellow eyes of patients with acute primary angle-closure measured by enhanced depth imaging spectral-domain optical coherence tomography.

    Science.gov (United States)

    Zhou, Minwen; Wang, Wei; Ding, Xiaoyan; Huang, Wenbin; Chen, Shida; Laties, Alan M; Zhang, Xiulan

    2013-03-19

    We evaluated choroidal thickness in the fellow eyes of patients with acute primary angle-closure (APAC) and compared findings to those of normal controls. The study group comprised 44 fellow eyes defined as primary angle-closure suspect (PACS) of 44 subjects who had experienced APAC and 43 eyes of 43 healthy volunteers. Using enhanced depth imaging optical coherence tomography (EDI-OCT), the peripapillary and macular choroidal thickness of the PACS eyes and the control eyes were measured and compared at each location or segment. Pearson correlation analysis and a multivariable regression model were used to evaluate the relationships between choroidal thickness and related factors. At all the macular locations, the choroidal thickness was thickest at the subfovea. The PACS eyes had a thicker choroid than the control eyes at all macular locations (all P 0.05). PACS eyes that had a fellow eye experience of APAC had a thicker macular choroid than the control eyes. The potential role of a thicker choroid as a risk factor for APAC must be investigated further.

  16. Numerical investigation of edge plasma phenomena in an enhanced D-alpha discharge at Alcator C-Mod: Parallel heat flux and quasi-coherent edge oscillations

    International Nuclear Information System (INIS)

    Russell, D. A.; D’Ippolito, D. A.; Myra, J. R.; LaBombard, B.; Terry, J. L.; Zweben, S. J.

    2012-01-01

    Reduced-model scrape-off layer turbulence (SOLT) simulations of an enhanced D-alpha (EDA) H-mode shot observed in the Alcator C-Mod tokamak were conducted to compare with observed variations in the scrape-off-layer (SOL) width of the parallel heat flux profile. In particular, the role of the competition between sheath- and conduction-limited parallel heat fluxes in determining that width was studied for the turbulent SOL plasma that emerged from the simulations. The SOL width decreases with increasing input power and with increasing separatrix temperature in both the experiment and the simulation, consistent with the strong temperature dependence of the parallel heat flux in balance with the perpendicular transport by turbulence and blobs. The particularly strong temperature dependence observed in the case analyzed is attributed to the fact that these simulations produce SOL plasmas which are in the conduction-limited regime for the parallel heat flux. A persistent quasi-coherent (QC) mode dominates the SOLT simulations and bears considerable resemblance to the QC mode observed in C-Mod EDA operation. The SOLT QC mode consists of nonlinearly saturated wave-fronts located just inside the separatrix that are convected poloidally by the mean flow, continuously transporting particles and energy and intermittently emitting blobs into the SOL.

  17. Secondary ions mass spectrometric signal enhancement of peptides on enlarged-gold nanoparticle surfaces.

    Science.gov (United States)

    Kim, Young-Pil; Lee, Tae Geol

    2012-06-05

    A high surface coverage of gold nanoparticles (AuNPs) is a prerequisite for enhancing the peptide signal intensity in time-of-flight secondary ion mass spectrometry (TOF-SIMS). Here, we demonstrate the TOF-SIMS signal amplification of peptides on a surface by enlarging surface-confined AuNPs using the NH(2)OH/Au(3+) seeding method. Because of the increased surface area and spherical structure of the Au, the SIMS intensity of the peptides became significantly enhanced on the enlarged-AuNPs surface, especially at high concentrations of peptide solution (>10 μM), compared to that of the bare gold surface or submonolyer of AuNPs. We are confident that this will be a useful method for diagnosis and bioassay with high sensitivity in a label-free manner.

  18. Immersion condensation on oil-infused heterogeneous surfaces for enhanced heat transfer.

    Science.gov (United States)

    Xiao, Rong; Miljkovic, Nenad; Enright, Ryan; Wang, Evelyn N

    2013-01-01

    Enhancing condensation heat transfer is important for broad applications from power generation to water harvesting systems. Significant efforts have focused on easy removal of the condensate, yet the other desired properties of low contact angles and high nucleation densities for high heat transfer performance have been typically neglected. In this work, we demonstrate immersion condensation on oil-infused micro and nanostructured surfaces with heterogeneous coatings, where water droplets nucleate immersed within the oil. The combination of surface energy heterogeneity, reduced oil-water interfacial energy, and surface structuring enabled drastically increased nucleation densities while maintaining easy condensate removal and low contact angles. Accordingly, on oil-infused heterogeneous nanostructured copper oxide surfaces, we demonstrated approximately 100% increase in heat transfer coefficient compared to state-of-the-art dropwise condensation surfaces in the presence of non-condensable gases. This work offers a distinct approach utilizing surface chemistry and structuring together with liquid-infusion for enhanced condensation heat transfer.

  19. Structural Origin of Enhanced Dynamics at the Surface of a Glassy Alloy

    Science.gov (United States)

    Sun, Gang; Saw, Shibu; Douglass, Ian; Harrowell, Peter

    2017-12-01

    The enhancement of mobility at the surface of an amorphous alloy is studied using a combination of molecular dynamic simulations and normal mode analysis of the nonuniform distribution of Debye-Waller factors. The increased mobility at the surface is found to be associated with the appearance of Arrhenius temperature dependence. We show that the transverse Debye-Waller factor exhibits a peak at the surface. Over the accessible temperature range, we find that the bulk and surface diffusion coefficients obey the same empirical relationship with the respective Debye-Waller factors. Extrapolating this relationship to lower T , we argue that the observed decrease in the constraint at the surface is sufficient to account for the experimentally observed surface enhancement of mobility.

  20. Surface tension gradient enhanced thin film flow for particle deposition

    Science.gov (United States)

    Gilchrist, James; Joshi, Kedar; Muangnapoh, Tanyakorn; Stever, Michael

    2015-11-01

    We investigate the effect of varying concentration in binary mixtures of water and ethanol as the suspending medium for micron-scale silica particles on convective deposition. By pulling a suspension along a substrate, a thin film is created that results in enhanced evaporation of the solvent and capillary forces that order particles trapped in the thin film. In pure water or pure ethanol, assembly and deposition is easily understood by a simply flux balance first developed by Dimitrov and Nagayama in 1996. In solvent mixtures having only a few percent of ethanol, Marangoni stresses from the concentration gradient set by unbalanced solvent evaporation dominates the thin film flow. The thin film profile is similar to that found in ``tears of wine'' where the particles are deposited in the thin film between the tears and the reservoir. A simple model describes the 10x increase of deposition speed found in forming well-ordered monolayers of particles. At higher ethanol concentrations, lateral instabilities also generated by Marangoni stresses cause nonuniform deposition in the form of complex streaks that mirror sediment deposits in larger scale flows. We acknowledge funding from the NSF Scalable Nanomanufacturing Program under grant No. 1120399.

  1. Surface plasmon enhanced organic solar cells with a MoO3 buffer layer.

    Science.gov (United States)

    Su, Zisheng; Wang, Lidan; Li, Yantao; Zhang, Guang; Zhao, Haifeng; Yang, Haigui; Ma, Yuejia; Chu, Bei; Li, Wenlian

    2013-12-26

    High-efficiency surface plasmon enhanced 1,1-bis-(4-bis(4-methyl-phenyl)-amino-phenyl)-cyclohexane:C70 small molecular bulk heterojunction organic solar cells with a MoO3 anode buffer layer have been demonstrated. The optimized device based on thermal evaporated Ag nanoparticles (NPs) shows a power conversion efficiency of 5.42%, which is 17% higher than the reference device. The improvement is attributed to both the enhanced conductivity and increased absorption due to the near-field enhancement of the localized surface plasmon resonance of Ag NPs.

  2. Enhancing osseointegration of orthopedic implants with titania nanotube surfaces

    Science.gov (United States)

    Baker, Erin A.

    Introduction: As joint arthroplasty surgical procedures increase annually, the development of new strategies, including novel materials and surface modifications, to attain solid bone-implant fixation are needed to increase implant terms of service. In this study, we evaluate two morphologies of titania nanotubes in both in vitro and in vivo experiments to quantify osseointegrative potential and material-level biocompatibility. Materials and Methods: Samples were prepared via an electrochemical etching process. Two different titania nanotube (TiNT) morphologies were produced, Aligned and Trabecular. For the in vitro experiment, Sprague Dawley (SD) rat marrow-derived bone marrow cells (BMC) were seeded on samples. Alkaline phosphatase (ALP) activity, osteocalcin (OC) expression, expression of relevant genes as well as cell attachment and morphology were assessed. In the first in vivo experiment, Kirschner wires were implanted unilaterally into SD rat femora with a TiNT-etched or unmodified (Control) implant. General health assessments and weekly body weights were recorded. At a 12-week endpoint, hematologic, systemic metal ion, and histologic analyses were performed. For the second in vivo experiment, Kirschner wires were implanted bilaterally into SD rat femora, with a TiNT-etched implant in one femora and unmodified (Control) implant as an internal control. At 4- and 12-week endpoints, femora were assessed via biomechanics, undecalcified histology, micro-computed tomography (muCT), and backscattered electron imaging (BEI) to characterize de novo bone formation. Results: In vitro experiments demonstrated BMC attachment and differentiation into osteoblasts as well as greater ALP activity, OC expression, total cell counts, and gene expression (of Col1a1, IGF-1, and osteonectin) on TiNT surfaces versus Controls. Cells on TiNT-etched substrates were smaller in diameter and more eccentric than Controls. In the first in vivo experiment, there were significant differences

  3. Enhanced surface sampler and process for collection and release of analytes

    Energy Technology Data Exchange (ETDEWEB)

    Addleman, Raymond S; Atkinson, David A; Bays, John T; Chouyyok, Wilaiwan; Cinson, Anthony D; Ewing, Robert G; Gerasimenko, Aleksandr A

    2015-02-03

    An enhanced swipe sampler and method of making are described. The swipe sampler is made of a fabric containing selected glass, metal oxide, and/or oxide-coated glass or metal fibers. Fibers are modified with silane ligands that are directly attached to the surface of the fibers to functionalize the sampling surface of the fabric. The swipe sampler collects various target analytes including explosives and other threat agents on the surface of the sampler.

  4. Multipitched Diffraction Gratings for Surface Plasmon Resonance-Enhanced Infrared Reflection Absorption Spectroscopy.

    Science.gov (United States)

    Petefish, Joseph W; Hillier, Andrew C

    2015-11-03

    We demonstrate the application of metal-coated diffraction gratings possessing multiple simultaneous pitch values for surface enhanced infrared absorption (SEIRA) spectroscopy. SEIRA increases the magnitude of vibrational signals in infrared measurements by one of several mechanisms, most frequently involving the enhanced electric field associated with surface plasmon resonance (SPR). While the majority of SEIRA applications to date have employed nanoparticle-based plasmonic systems, recent advances have shown how various metals and structures lead to similar signal enhancement. Recently, diffraction grating couplers have been demonstrated as a highly tunable platform for SEIRA. Indeed, gratings are an experimentally advantageous platform due to the inherently tunable nature of surface plasmon excitation at these surfaces since both the grating pitch and incident angle can be used to modify the spectral location of the plasmon resonance. In this work, we use laser interference lithography (LIL) to fabricate gratings possessing multiple pitch values by subjecting photoresist-coated glass slides to repetitive exposures at varying orientations. After metal coating, these gratings produced multiple, simultaneous plasmon peaks associated with the multipitched surface, as identified by infrared reflectance measurements. These plasmon peaks could then be coupled to vibrational modes in thin films to provide localized enhancement of infrared signals. We demonstrate the flexibility and tunability of this platform for signal enhancement. It is anticipated that, with further refinement, this approach might be used as a general platform for broadband enhancement of infrared spectroscopy.

  5. Project proposal for surface-mined land enhancement (SMILE)

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, A.M.

    1975-01-29

    Reclaiming strip-mined land is a program ideally suited to meet the requirements of the Job Opportunities Program. It will provide healthy and vigorous outdoor activity involving surveying, earth-moving, revegetation, tree planting, construction of roads, paths, lakes, and park facilities. It is work which states and communities are anxious to have started. It can be done with relatively small capital expenditure. Technical expertise is available in the various states concerned. FEA is the ideal agency to initiate such a project. It has regional offices throughout the country with close contacts with states and local communities. It is a temporary emergency agency with considerable experience in initiating and carrying out crash programs. It is not tied down to the procedures and bureaucratic problems which burden an old-line agency attempting to take on new work. Finally, FEA has a vital interest in energy and surface mining in particular. It played a major role in drafting the new legislation. The initial program development is described, including the technical aspects, economic aspects and administration, cost, budget, cooperation with state agencies, etc.

  6. Optimizing critical heat flux enhancement through nano-particle-based surface modifications

    International Nuclear Information System (INIS)

    Truong, B.; Hu, L. W.; Buongiorno, J.

    2008-01-01

    Colloidal dispersions of nano-particles, also known as nano-fluids, have shown to yield significant Critical Heat Flux (CHF) enhancement. The CHF enhancement mechanism in nano-fluids is due to the buildup of a porous layer of nano-particles upon boiling. Unlike microporous coatings that had been studied extensively, nano-particles have the advantages of forming a thin layer on the substrate with surface roughness ranges from the sub-micron to several microns. By tuning the chemical properties it is possible to coat the nano-particles in colloidal dispersions onto the desired surface, as has been demonstrated in engineering thin film industry. Building on recent work conducted at MIT, this paper illustrates the maximum CHF enhancement that can be achieved based on existing correlations. Optimization of the CHF enhancement by incorporation of key factors, such as the surface wettability and roughness, will also be discussed. (authors)

  7. Enhancement of the Laser Transmission Weldability between Polyethylene and Polyoxymethylene by Plasma Surface Treatment

    Directory of Open Access Journals (Sweden)

    Huixia Liu

    2017-12-01

    Full Text Available Due to their large compatibility difference, polyethylene (PE and polyoxymethylene (POM cannot be welded together by laser transmission welding. In this study, PE and POM are pretreated using plasma that significantly enhances their laser transmission welding strength. To understand the mechanism underlying the laser welding strength enhancement, surface modification is analyzed using contact angle measurements, atomic force microscopy (AFM, optical microscopy, and X-ray photoelectron spectroscopy (XPS. Characterization results show that the plasma surface treatment improves the surface free energy, significantly enhancing the wettability of the materials. The increase in surface roughness and the generation of homogeneous bubbles contribute to the formation of mechanical micro-interlocking. The oxygen-containing groups introduced by the oxygen plasma treatment improve the compatibility of PE and POM, and facilitate the diffusion and entanglement of molecular chains and the formation of van der Waals force.

  8. Enhanced biogenic emissions of nitric oxide and nitrous oxide following surface biomass burning

    Science.gov (United States)

    Anderson, Iris C.; Levine, Joel S.; Poth, Mark A.; Riggan, Philip J.

    1988-01-01

    Recent measurements indicate significantly enhanced biogenic soil emissions of both nitric oxide (NO) and nitrous oxide (N2O) following surface burning. These enhanced fluxes persisted for at least six months following the burn. Simultaneous measurements indicate enhanced levels of exchangeable ammonium in the soil following the burn. Biomass burning is known to be an instantaneous source of NO and N2O resulting from high-temperature combustion. Now it is found that biomass burning also results in significantly enhanced biogenic emissions of these gases, which persist for months following the burn.

  9. Development of surface wettability characteristics for enhancing pool boiling heat transfer

    International Nuclear Information System (INIS)

    Kim, Moo Hwan; Jo, Hang Jin

    2010-05-01

    For several centuries, many boiling experiments have been conducted. Based on literature survey, the characteristic of heating surface in boiling condition played as an important role which mainly influenced to boiling performance. Among many surface factor, the fact that wettability effect is significant to not only the enhancement of critical heat flux(CHF) but also the nucleate boiling heat transfer is also supported by other kinds of boiling experiments. In this regard, the excellent boiling performance (a high CHF and heat transfer performance) in pool boiling could be achieved through some favorable surface modification which satisfies the optimized wettability condition. To find the optimized boiling condition, we design the special heaters to examine how two materials, which have different wettability (e.g. hydrophilic and hydrophobic), affect the boiling phenomena. The special heaters have hydrophobic dots on hydrophilic surface. The contact angle of hydrophobic surface is 120 .deg. to water at the room temperature. The contact angle of hydrophilic surface is 60 .deg. at same conditions. To conduct the experiment with new surface condition, we developed new fabrication method and design the pool boiling experimental apparatus. Through this facility, we can the higher CHF on pattern surface than that on hydrophobic surface, and the higher boiling heat transfer performance on pattern surface than that on hydrophilic surface. Based on this experimental results, we concluded that we proposed new heating surface condition and surface fabrication method to realize the best boiling condition by modified heating surface condition

  10. Plasma Surface Modification of Glass-Fibre-Reinforced Polyester Enhanced by Ultrasonic Irradiation

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Singh, Shailendra Vikram; Bardenshtein, Alexander

    2010-01-01

    .295, 0.385 and 0.447, respectively. This indicated that the plasma treatment oxidized and roughened the GFRP surface, and the ultrasonic irradiation further enhanced the oxidation. It is concluded that plasma treatment efficiency for adhesion improvement of GFRPs is enhanced by the ultrasonic irradiation.......During atmospheric pressure plasma treatment, reactive species generated in the plasma diffuse through a boundary gas layer which is adsorbed at the material surface. Many of the reactive species become inactivated before reaching the surface due to their short lifetime. The efficiency of plasma....... The surface characterizations were performed using contact angle measurements, X-ray photoelectron spectroscopy (XPS) and atomic force mictroscopy (AFM). O/C ratios at the GFRP surfaces before the treatments, after 30-s plasma treatment, and after 30-s plasma treatment with ultrasonic irradiation were 0...

  11. Nocturnal surface ozone enhancement over Portugal during winter: Influence of different atmospheric conditions

    KAUST Repository

    Kulkarni, Pavan S.

    2016-09-24

    Four distinct nocturnal surface ozone (NSO) enhancement events were observed, with NSO concentration exceeding 80μg/m3, at multiple ozone (O3) monitoring stations (32 sites) in January, November and December between year 2000–2010, in Portugal. The reasonable explanation for the observed bimodal pattern of surface ozone with enhanced NSO concentration during nighttime has to be transport processes, as the surface ozone production ceases at nighttime. Simultaneous measurements of O3 at multiple stations during the study period in Portugal suggest that horizontal advection alone cannot explain the observed NSO enhancement. Thus, detailed analysis of the atmospheric conditions, simulated with the Weather Research and Forecasting (WRF) model, were performed to evaluate the atmospheric mechanisms responsible for NSO enhancement in the region. Simulations revealed that each event occurred as a result of one or the combination of different atmospheric processes such as, passage of a cold front followed by a subsidence zone; passage of a moving surface trough, with associated strong horizontal wind speed and vertical shear; combination of vertical and horizontal transport at the synoptic scale; formation of a low level jet with associated vertical mixing below the jet stream. The study confirmed that large-scale flow pattern resulting in enhanced vertical mixing in the nocturnal boundary layer, plays a key role in the NSO enhancement events, which frequently occur over Portugal during winter months. © 2016 Elsevier Ltd

  12. Surface-Passivated AlGaN Nanowires for Enhanced Luminescence of Ultraviolet Light Emitting Diodes

    KAUST Repository

    Sun, Haiding

    2017-12-19

    Spontaneously-grown, self-aligned AlGaN nanowire ultraviolet light emitting diodes still suffer from low efficiency partially because of the strong surface recombination caused by surface states, i.e., oxidized surface and high density surface states. Several surface passivation methods have been introduced to reduce surface non-radiative recombination by using complex and toxic chemicals. Here, we present an effective method to suppress such undesirable surface recombination of the AlGaN nanowires via diluted potassium hydroxide (KOH) solution; a commonly used chemical process in semiconductor fabrication which is barely used as surface passivation solution in self-assembled nitride-based nanowires. The transmission electron microscopy investigation on the samples reveals almost intact nanowire structures after the passivation process. We demonstrated an approximately 49.7% enhancement in the ultraviolet light output power after 30-s KOH treatment on AlGaN nanowires grown on titanium-coated silicon substrates. We attribute such a remarkable enhancement to the removal of the surface dangling bonds and oxidized nitrides (Ga-O or Al-O bonds) at the surface as we observe the change of the carrier lifetime before and after the passivation. Thus, our results highlight the possibility of employing this process for the realization of high performance nanowire UV emitters.

  13. Thermal performance enhancement of erythritol/carbon foam composites via surface modification of carbon foam

    Science.gov (United States)

    Li, Junfeng; Lu, Wu; Luo, Zhengping; Zeng, Yibing

    2017-03-01

    The thermal performance of the erythritol/carbon foam composites, including thermal diffusivity, thermal capacity, thermal conductivity and latent heat, were investigated via surface modification of carbon foam using hydrogen peroxide as oxider. It was found that the surface modification enhanced the wetting ability of carbon foam surface to the liquid erythritol of the carbon foam surface and promoted the increase of erythritol content in the erythritol/carbon foam composites. The dense interfaces were formed between erythritol and carbon foam, which is due to that the formation of oxygen functional groups C=O and C-OH on the carbon surface increased the surface polarity and reduced the interface resistance of carbon foam surface to the liquid erythritol. The latent heat of the erythritol/carbon foam composites increased from 202.0 to 217.2 J/g through surface modification of carbon foam. The thermal conductivity of the erythritol/carbon foam composite before and after surface modification further increased from 40.35 to 51.05 W/(m·K). The supercooling degree of erythritol also had a large decrease from 97 to 54 °C. Additionally, the simple and effective surface modification method of carbon foam provided an extendable way to enhance the thermal performances of the composites composed of carbon foams and PCMs.

  14. Gliding arc surface treatment of glass fibre reinforced polyester enhanced by ultrasonic irradiation

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Singh, Shailendra Vikram; Bardenshtein, Alexander

    2010-01-01

    that polar functional groups were introduced at the surface by the gliding arc treatment, and that the treatment efficiency was enhanced by the ultrasonic irradiation, indicating that the adhesive property would be improved. The results are extensively discussed in terms of the plasma conditions......During atmospheric pressure plasma surface treatment, reactive species generated in the plasma diffuse through a boundary gas layer which sticks at the material surface. Due to the short lifetime of these species only a small fraction can reach the surface, limiting the surface treatment efficiency...... of approximately 150 dB were introduced vertically to the GFRP surface through a cylindrical waveguide. The water contact angle of the GFRP surface dropped markedly with no ultrasonic irradiation, and tended to decrease furthermore at higher power. Ultrasonic irradiation during the plasma treatment consistently...

  15. Surface-enhanced localized surface plasmon resonance biosensing of avian influenza DNA hybridization using subwavelength metallic nanoarrays

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Shin Ae; Jang, Sung Min; Kim, Sung June [School of Electrical Engineering and Computer Science, Seoul National University, Seoul 151-742 (Korea, Republic of); Byun, Kyung Min [Department of Biomedical Engineering, Kyung Hee University, Yongin 446-701 (Korea, Republic of); Kim, Kyujung; Kim, Donghyun [Program of Nanomedical Science and Technology, Yonsei University, Seoul 120-749 (Korea, Republic of); Ma, Kyungjae; Oh, Youngjin [School of Electrical and Electronic Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Kim, Sung Guk [College of Veterinary Medicine, Cornell University, Ithaca, New York 14853 (United States); Shuler, Michael L, E-mail: kmbyun@khu.ac.kr [Department of Biomedical Engineering, Cornell University, Ithaca, New York 14853 (United States)

    2010-09-03

    We demonstrated enhanced localized surface plasmon resonance (SPR) biosensing based on subwavelength gold nanoarrays built on a thin gold film. Arrays of nanogratings (1D) and nanoholes (2D) with a period of 200 nm were fabricated by electron-beam lithography and used for the detection of avian influenza DNA hybridization. Experimental results showed that both nanoarrays provided significant sensitivity improvement and, especially, 1D nanogratings exhibited higher SPR signal amplification compared with 2D nanohole arrays. The sensitivity enhancement is associated with changes in surface-limited reaction area and strong interactions between bound molecules and localized plasmon fields. Our approach is expected to improve both the sensitivity and sensing resolution and can be applicable to label-free detection of DNA without amplification by polymerase chain reaction.

  16. Surface modification of Cobalt ferrite nano-hollowspheres for inherent multiple photoluminescence and enhanced photocatalytic activities

    Science.gov (United States)

    Talukdar, Souvanik; Mandal, Dipika; Mandal, Kalyan

    2017-03-01

    Nano-hollow spheres (NHSs) are the new drift in magnetic nanostructures as they provide more surface area at nano length scale with enhanced magnetic properties compared to their nanoparticle counterpart. Here we reported the synthesis of biocompatible CoFe2O4 NHSs of diameter around 250 nm and emergence of intrinsic multiple photoluminescence from blue, green to red on modifying their surface with small organic ligands like tartrate. The surface modified NHSs also showed notable photocatalytic activity towards the degradation of environmentally malefic dyes like Methylene Blue and Rhodamine B. The surface modified NHSs are found to exhibit superior magnetic properties.

  17. Surface-enhanced raman spectroscopy substrate for arsenic sensing in groundwater

    Science.gov (United States)

    Yang, Peidong; Mulvihill, Martin; Tao, Andrea R.; Sinsermsuksakul, Prasert; Arnold, John

    2015-06-16

    A surface-enhanced Raman spectroscopy (SERS) substrate formed from a plurality of monolayers of polyhedral silver nanocrystals, wherein at least one of the monolayers has polyvinypyrrolidone (PVP) on its surface, and thereby configured for sensing arsenic is described. Highly active SERS substrates are formed by assembling high density monolayers of differently shaped silver nanocrystals onto a solid support. SERS detection is performed directly on this substrate by placing a droplet of the analyte solution onto the nanocrystal monolayer. Adsorbed polymer, polyvinypyrrolidone (PVP), on the surface of the nanoparticles facilitates the binding of both arsenate and arsenite near the silver surface, allowing for highly accurate and sensitive detection capabilities.

  18. Coherent dynamics in semiconductors

    DEFF Research Database (Denmark)

    Hvam, Jørn Märcher

    1998-01-01

    enhanced in quantum confined lower-dimensional systems, where exciton and biexciton effects dominate the spectra even at room temperature. The coherent dynamics of excitons are at modest densities well described by the optical Bloch equations and a number of the dynamical effects known from atomic......Ultrafast nonlinear optical spectroscopy is used to study the coherent dynamics of optically excited electron-hole pairs in semiconductors. Coulomb interaction implies that the optical inter-band transitions are dominated, at least at low temperatures, by excitonic effects. They are further...... and molecular systems are found and studied in the exciton-biexciton system of semiconductors. At densities where strong exciton interactions, or many-body effects, become dominant, the semiconductor Bloch equations present a more rigorous treatment of the phenomena Ultrafast degenerate four-wave mixing is used...

  19. Enhanced oxygen reduction activity on surface-decorated perovskite thin films for solid oxide fuel cells

    KAUST Repository

    Mutoro, Eva

    2011-01-01

    Surface-decoration of perovskites can strongly affect the oxygen reduction activity, and therefore is a new and promising approach to improve SOFC cathode materials. In this study, we demonstrate that a small amount of secondary phase on a (001) La 0.8Sr 0.2CoO 3-δ (LSC) surface can either significantly activate or passivate the electrode. LSC (001) microelectrodes prepared by pulsed laser deposition on a (001)-oriented yttria-stabilized zirconia (YSZ) substrate were decorated with La-, Co-, and Sr-(hydr)oxides/carbonates. "Sr"-decoration with nanoparticle coverage in the range from 50% to 80% of the LSC surface enhanced the surface exchange coefficient, k q, by an order of magnitude while "La"- decoration and "Co"-decoration led to no change and reduction in k q, respectively. Although the physical origin for the enhancement is not fully understood, results from atomic force microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy suggest that the observed k q enhancement for "Sr"-decorated surfaces can be attributed largely to catalytically active interface regions between surface Sr-enriched particles and the LSC surface. © 2011 The Royal Society of Chemistry.

  20. Enhancement of nitric oxide release and hemocompatibility by surface chirality of D-tartaric acid grafting

    Science.gov (United States)

    Han, Honghong; Wang, Ke; Fan, Yonghong; Pan, Xiaxin; Huang, Nan; Weng, Yajun

    2017-12-01

    Nitric Oxide (NO) generation from endogenous NO-donors catalyzed by diselenide modified biomaterials has been reported. Here we reported surface chirality by L-tartaric acid and D-tartaric acid grafting on the outermost showed a significant impact on diselenide modified biomaterials, which modulated protein adsorption, NO release and anti-platelet adhesion properties. D-tartaric acid grafted surface showed more blood protein adsorption than that of L-surfaces by QCM analysis, however, ELISA analysis disclosed less fibrinogen denatured on the D surfaces. Due to the surface ratio of selenium decreasing, NO release catalyzed by L-tartaric acid grafting on the outermost significantly decreased in comparison to that of only selenocystamine immobilized surfaces. While NO release catalyzed by D-tartaric acid grafting on the outermost didn't decrease and was similar with that of selenocystamine immobilized surfaces. Surface chirality combined with NO release had synergetic effects on platelet adhesion, and it showed the lowest number of platelets adhered on the D-tartaric acid grafted surfaces. Thus surface chirality from D-tartaric acid grafting enhanced hemocompatibility of the surface in this study. Our work provides new insights into engineering novel blood contacting biomaterials by taking into account surface chirality.

  1. Enhanced biocompatibility of TiO2 surfaces by highly reactive plasma

    International Nuclear Information System (INIS)

    Junkar, Ita; Recek, Nina; Kovač, Janez; Mozetič, Miran; Kulkarni, Mukta; Iglič, Aleš; Drašler, Barbara; Rugelj, Neža; Drobne, Damjana; Humpolicek, Petr

    2016-01-01

    In the present study the biological response to various nanotopographic features after gaseous plasma treatment were studied. The usefulness of nanostructured surfaces for implantable materials has already been acknowledged, while less is known on the combined effect of nanostructured plasma modified surfaces. In the present work the influence of oxygen plasma treatment on nanostructured titanium oxide (TiO 2 ) surfaces was studied. Characterization of the TiO 2 surface chemical composition and morphological features was analyzed after plasma modification by x-ray photoelectron spectroscopy and by scanning electron microscopy while surface wettability was studied with measuring the water contact angle. Cell adhesion and morphology was assessed from images taken with scanning electron microscopy, whereas cell viability was measured with a calorimetric assay. The obtained results showed that oxygen plasma treatment of TiO 2 nanotube surfaces significantly influences the adhesion and morphology of osteoblast-like cells in comparison to untreated nanostructured surfaces. Marked changes in surface composition of plasma treated surfaces were observed, as plasma treatment removed hydrocarbon contamination and removed fluorine impurities, which were present due to the electrochemical anodization process. However no differences in wettability of untreated and plasma treated surfaces were noticed. Treatment with oxygen plasma stimulated osteoblast-like cell adhesion and spreading on the nanostructured surface, suggesting the possible use of oxygen plasma surface treatment to enhance osteoblast-like cell response. (paper)

  2. Surface-enhanced Raman scattering from metal and transition metal nano-caped arrays

    Science.gov (United States)

    Sun, Huanhuan; Gao, Renxian; Zhu, Aonan; Hua, Zhong; Chen, Lei; Wang, Yaxin; Zhang, Yongjun

    2018-03-01

    The metal and transition metal cap-shaped arrays on polystyrene colloidal particle (PSCP) templates were fabricated to study the surface-enhanced Raman scattering (SERS) effect. We obtained the Ag and Fe complex film by a co-sputtering deposition method. The size of the deposited Fe particle was changed by the sputtering power. We also study the SERS enhancement mechanism by decorating the PATP probe molecule on the different films. The SERS signals increased firstly, and then decreased as the size of Fe particles grows gradually. The finite-difference time domain (FDTD) simulation and experimental Raman results manifest that SERS enhancement was mainly attributed to surface plasma resonance (SPR) between Ag and Ag nanoparticles. The SERS signals of PATP molecule were enhanced to reach a lowest detectable concentration of 10-8 mol/L. The research demonstrates that the SERS substrates with Ag-Fe cap-shaped arrays have a high sensitivity.

  3. Surface-Enhanced Raman Scattering Using Silica Whispering-Gallery Mode Resonators

    Science.gov (United States)

    Anderson, Mark S.

    2013-01-01

    The motivation of this work was to have robust spectroscopic sensors for sensitive detection and chemical analysis of organic and molecular compounds. The solution is to use silica sphere optical resonators to provide surface-enhanced spectroscopic signal. Whispering-gallery mode (WGM) resonators made from silica microspheres were used for surface-enhanced Raman scattering (SERS) without coupling to a plasmonic mechanism. Large Raman signal enhancement is observed by exclusively using 5.08-micron silica spheres with 785-nm laser excitation. The advantage of this non-plasmonic approach is that the active substrate is chemically inert silica, thermally stable, and relatively simple to fabricate. The Raman signal enhancement is broadly applicable to a wide range of molecular functional groups including aliphatic hydrocarbons, siloxanes, and esters. Applications include trace organic analysis, particularly for in situ planetary instruments that require robust sensors with consistent response.

  4. Coherent laser vision system

    International Nuclear Information System (INIS)

    Sebastion, R.L.

    1995-01-01

    The Coherent Laser Vision System (CLVS) is being developed to provide precision real-time 3D world views to support site characterization and robotic operations and during facilities Decontamination and Decommissioning. Autonomous or semiautonomous robotic operations requires an accurate, up-to-date 3D world view. Existing technologies for real-time 3D imaging, such as AM laser radar, have limited accuracy at significant ranges and have variability in range estimates caused by lighting or surface shading. Recent advances in fiber optic component technology and digital processing components have enabled the development of a new 3D vision system based upon a fiber optic FMCW coherent laser radar. The approach includes a compact scanner with no-moving parts capable of randomly addressing all pixels. The system maintains the immunity to lighting and surface shading conditions which is characteristic to coherent laser radar. The random pixel addressability allows concentration of scanning and processing on the active areas of a scene, as is done by the human eye-brain system

  5. Chloride salt enhancement and stabilization of the photoluminescence from a porous silicon surface

    Science.gov (United States)

    Gole, James L.; Devincentis, Julie A.; Seals, Lenward; Lillehei, Peter T.; Prokes, S. M.; Dixon, David A.

    2000-02-01

    In a postetch treatment, chloride salts are used to greatly enhance and stabilize the photoluminescence (PL) from a porous silicon (PS) surface. We compare the enhancement and stabilization induced by solutions of the strong acid HCl (H++Cl-), saturated NaCl (in MeOH, where Me denotes methyl), and a tetrabutylammonium perchlorate [TBAP(Cl-)] solution. The extent and duration of the stabilization process and its dependence on the chloride-ion concentration, the identity of the cation, and the solvent composition are outlined and contrasted to strongly quenching NaF (Na++F-) and NaOH (Na++OH-) treatments. Treatment with HCl is found to produce the most efficient enhancement of the PL signal. The H+- and Cl--ion concentrations in solution are critical as the stability of the strong HCl-induced enhancement of the nitrogen-laser-induced luminescence from the PS surface depends, as well, on the presence of methanol. PS surfaces treated in an HCl/H2O solution display a strongly enhanced in situ luminescence, which decays rapidly in an ex situ environment without treatment in ultrahigh-purity (UHP) methanol. Samples treated in an HCl(H2O)/MeOH solution (greater than 2M) maintain their enhancement for extended periods. Chloride-ion stabilization appears independent of the method of preparing the PS structure, implying that chloride salt treatment largely stabilizes the surface structure of the luminescent PS. Scanning electron micrographs demonstrate the profound change that accompanies the HCl treatment of the PS surface. Energy dispersive spectroscopy reveals chloride incorporation into the PS surface at strongly photoluminescent regions. Raman scattering demonstrates that the PL is correlated with the creation of amorphous structural regions. In conjunction with detailed quantum-chemical modeling, in which we examine the derivatization of the PS surface, time-dependent histograms obtained for the HCl-treated systems indicate that the resulting luminescence, initiated

  6. Silver-graphene oxide based plasmonic spacer for surface plasmon-coupled fluorescence emission enhancements

    Science.gov (United States)

    Badiya, Pradeep Kumar; Srinivasan, Venkatesh; Sathish Ramamurthy, Sai

    2017-06-01

    We report the application of single layered graphene oxide (SLGO) and silver decorated SLGO (Ag-SLGO) as plasmonic spacer material for obtaining enhanced fluorescence from a Rhodamine 6G (Rh6G) radiating dipole in a surface plasmon-coupled emission platform. To this end, we have decorated SLGO with biphasic silver nanoparticles using an in situ deposition technique to achieve 112-fold fluorescence enhancements.

  7. Fabrication and Characterization of the US Army Research Laboratory Surface Enhanced Raman Scattering (SERS) Substrates

    Science.gov (United States)

    2017-12-04

    enhancement. The chemical enhancement occurs when there is a charge transfer resonance between the molecule and the metalized surface. These effects can also...various genes, chemical warfare species, bacteria,60,108–114 diagnostic markers, environmental pollutants , glucose monitoring,102,115 and stress...Inspired Materials 5 1.2 US Army-Relevant Applications of SERS-Hazard Detection 7 1.3 Assessing SERS Substrate: ARL/Edgewood Chemical Biological

  8. Friction surfacing for enhanced surface protection of marine engineering components: erosion-corrosion study

    Science.gov (United States)

    Rajakumar, S.; Balasubramanian, V.; Balakrishnan, M.

    2016-08-01

    Good mechanical properties combined with outstanding corrosion-resistance properties of cast nickel-aluminum bronze (NAB) alloy lead to be a specific material for many marine applications, including ship propellers. However, the erosion-corrosion resistance of cast-NAB alloy is not as good as wrought NAB alloy. Hence, in this investigation, an attempt has been made to improve the erosion-corrosion resistance of cast NAB alloy by depositing wrought (extruded) NAB alloy applying the friction surfacing (FS) technique. Erosion-corrosion tests were carried out in slurries composed of sand particles of 3.5% NaCl solution. Silica sand having a nominal size range of 250-355 μm is used as an erodent. Specimens were tested at 30° and 90° impingement angles. It is observed that the erosion and erosion-corrosion resistance of friction surfaced NAB alloy exhibited an improvement as compared to cast NAB alloy. Scanning electron microscope (SEM) analysis showed that the erosion tracks developed on the cast NAB alloy were wider and deeper than those formed on the friction surfaced extruded NAB alloy.

  9. Surface enhanced Raman optical activity as an ultra sensitive tool for ligand binding analysis

    DEFF Research Database (Denmark)

    Johannessen, Christian; Abdali, Salim

    2007-01-01

    The Surface Enhanced Resonance Raman Scattering (SERRS) and Surface Enhanced Resonance Raman Optical Activity (SERROA) spectra of myoglobin and the myoglobin-azide complex were measured on very dilute samples (100 nM protein) in order to analyze the sensitivity of SERROA spectroscopy when inducing...... upon azide complexation. Application of this method allows for rapid analysis of ligand binding in metalloproteins in dilute aqueous solution and could in the future, when combined with theoretical studies, increase the obtainable structural resolution of proteins beyond that of X-ray analysis....

  10. Enhancement in the photodetection of ZnO nanowires by introducing surface-roughness-induced traps

    International Nuclear Information System (INIS)

    Park, Woojin; Jo, Gunho; Hong, Woong-Ki; Yoon, Jongwon; Choe, Minhyeok; Ji, Yongsung; Kim, Geunjin; Kahng, Yung Ho; Lee, Kwanghee; Lee, Takhee; Lee, Sangchul; Wang, Deli

    2011-01-01

    We investigated the enhanced photoresponse of ZnO nanowire transistors that was introduced with surface-roughness-induced traps by a simple chemical treatment with isopropyl alcohol (IPA). The enhanced photoresponse of IPA-treated ZnO nanowire devices is attributed to an increase in adsorbed oxygen on IPA-induced surface traps. The results of this study revealed that IPA-treated ZnO nanowire devices displayed higher photocurrent gains and faster photoswitching speed than transistors containing unmodified ZnO nanowires. Thus, chemical treatment with IPA can be a useful method for improving the photoresponse of ZnO nanowire devices.

  11. Surface-enhanced Raman imaging of fractal shaped periodic metal nanostructures

    DEFF Research Database (Denmark)

    Beermann, Jonas; Novikov, Sergey Mikhailovich; Albrektsen, Ole

    2009-01-01

    Surface-enhanced Raman scattering (SERS) from Rhodamine 6G (R6G) homogenously adsorbed on fractal shaped 170-nm-period square arrays formed by 50-nm-high gold nanoparticles (diameters of 80, 100, or 120 nm are constant within each array), fabricated on a smooth gold film by electron-beam lithogra......Surface-enhanced Raman scattering (SERS) from Rhodamine 6G (R6G) homogenously adsorbed on fractal shaped 170-nm-period square arrays formed by 50-nm-high gold nanoparticles (diameters of 80, 100, or 120 nm are constant within each array), fabricated on a smooth gold film by electron...

  12. Vesicles containing ion channels on crystalline surfaces-An FTIR and surface enhanced FTIR spectroscopic study

    Science.gov (United States)

    Fischer, W. B.; Unverricht, I.; Kuhne, Ch.; Steiner, G.; Schrattenholz, A.; Maelicke, A.; Salzer, R.

    1998-06-01

    The kinetics of the adsorption of native vesicles containing the nicotinic acetylcholine receptor (nAChR) is monitored by ATR-FTIR and SEIRA spectroscopy. The membrane vesicles are adsorbed on Ge crystals. Experiments are done with neat Ge and with Ge crystals covered with a thin layer of silver clusters in order to obtain the enhancement effect of infrared adsorption. The nAChR shows β-sheet/turn structures at the interface. These results give evidence for the existence of these structures in the extracellular domains of the receptor. The potential for SEIRA in the investigation of proteins at interfaces and membrane processes is outlined.

  13. Quantitative Detection of Trace Level Cloxacillin in Food Samples Using Magnetic Molecularly Imprinted Polymer Extraction and Surface-Enhanced Raman Spectroscopy Nanopillars

    DEFF Research Database (Denmark)

    Ashley, Jon; Wu, Kaiyu; Hansen, Mikkel Fougt

    2017-01-01

    using an internal standard. By coherently combining MMIP extraction and silicon nanopillar-based SERS biosensor, good sensitivity toward cloxacillin was achieved. The detection limit was 7.8 pmol. Cloxacillin recoveries from spiked pig plasma samples were found to be more than 80%.......There is an increasing demand for rapid, sensitive, and low cost analytical methods to routinely screen antibiotic residues in food products. Conventional detection of antibiotics involves sample preparation by liquid-liquid or solid-phase extraction, followed by analysis using liquid...... with surface-enhanced Raman spectroscopy (SERS)-based detection for quantitative analysis of cloxacillin in pig serum. MMIP microspheres were synthesized using a core-shell technique. The large loading capacity and high selectivity of the MMIP microspheres enabled efficient extraction of cloxacillin, while...

  14. Surface enhancement of cold work tool steels by friction stir processing with a pinless tool

    Science.gov (United States)

    Costa, M. I.; Verdera, D.; Vieira, M. T.; Rodrigues, D. M.

    2014-03-01

    The microstructure and mechanical properties of enhanced tool steel (AISI D2) surfaces produced using a friction stir welding (FSW) related procedure, called friction stir processing (FSP), are analysed in this work. The surface of the tool steel samples was processed using a WC-Co pinless tool and varying processing conditions. Microstructural analysis revealed that meanwhile the original substrate structure consisted of a heterogeneous distribution of coarse carbides in a ferritic matrix, the transformed surfaces consisted of very small carbides, homogenously distributed in a ferrite- bainite- martensite matrix. The morphology of the surfaces, as well as its mechanical properties, evaluated by hardness and tensile testing, were found to vary with increasing tool rotation speed. Surface hardness was drastically increased, relative to the initial hardness of bulk steel. This was attributed to ferrite and carbide refinement, as well as to martensite formation during solid state processing. At the highest rotation rates, tool sliding during processing deeply compromised the characteristics of the processed surfaces.

  15. Coherence and Sense of Coherence

    DEFF Research Database (Denmark)

    Dau, Susanne

    2014-01-01

    examined is how activating of models of blended learning in undergraduate education for teacher and radiograph affects the knowledge development. This is approached by mixed methods. The empirical data consist of data from surveys as well as focus group interviews and some observation studies. These data...... are analyzed and interpreted through a critical hermeneutical process of prefiguration, configuration and re-figuration. The findings illustrate significantly importance of sense of coherence among participants as a condition for implementing new designs and new learning environments. It is revealed that sense...

  16. An experimental method to determine the electrostatic field enhancement factor of a practical conductor surface

    DEFF Research Database (Denmark)

    McAllister, Iain Wilson; Crichton, George C

    1989-01-01

    A method of determining the field enhancement factor of a practical conductor is presented. The method is developed from a modified theory of discharge onset in a gaseous medium. This modification incorporates the influence of conductor surface roughness. Onset data from an experimental study...... that utilized electrodes of varying surface roughness are examined, and the results obtained using the proposed method are discussed with reference to both the underlying theory and the practical aspects of the experimental measurements...

  17. Can solvent induced surface modifications applied to screen-printed platforms enhance their electroanalytical performance?

    OpenAIRE

    Blanco, Elías; Foster, Christopher W.; Cumba, Loanda R.; Camo, Devaney R. do; Banks, Craig E.

    2016-01-01

    In this paper the effect of solvent induced chemical surface enhancements upon graphitic screen-printed electrodes (SPEs) is explored. Previous literature has indicated that treating the working electrode of a SPE with the solvent N,N-dimethylformamide (DMF) offers improvements within the electroanalytical response, resulting in a 57-fold increment in the electrode surface area compared to their unmodified counterparts. The protocol involves two steps: (i) the SPE is placed into DMF for a sel...

  18. Surface-Enhanced Raman Scattering of the Complexes of Silver with Adenine and dAMP

    OpenAIRE

    Otto, Cornelis; Hoeben, F.P.; Hoeben, F.P.; Greve, Jan

    1991-01-01

    The behaviour of adenine and 2'-deoxyadenosine-5'-monophosphate (dAMP) at positive surface potentials of a silver working electrode was investigated using surface-enhanced Raman scattering (SERS). The use of positive potentials in the presence of adenine or dAMP leads to a rapid accumulation of an intense spectrum. It is proposed that complexes of adenine (dAMP) with silver generate the observed spectra. Adenine and dAMP can be distinguished spectroscopically due to various different complexe...

  19. Surface enhanced Raman spectroscopy: A review of recent applications in forensic science.

    Science.gov (United States)

    Fikiet, Marisia A; Khandasammy, Shelby R; Mistek, Ewelina; Ahmed, Yasmine; Halámková, Lenka; Bueno, Justin; Lednev, Igor K

    2018-05-15

    Surface enhanced Raman spectroscopy has many advantages over its parent technique of Raman spectroscopy. Some of these advantages such as increased sensitivity and selectivity and therefore the possibility of small sample sizes and detection of small concentrations are invaluable in the field of forensics. A variety of new SERS surfaces and novel approaches are presented here on a wide range of forensically relevant topics. Copyright © 2018 Elsevier B.V. All rights reserved.

  20. Surface Passivation of GaN Nanowires for Enhanced Photoelectrochemical Water-Splitting

    KAUST Repository

    Varadhan, Purushothaman

    2017-02-08

    Hydrogen production via photoelectrochemical water-splitting is a key source of clean and sustainable energy. The use of one-dimensional nanostructures as photoelectrodes is desirable for photoelectrochemical water-splitting applications due to the ultralarge surface areas, lateral carrier extraction schemes, and superior light-harvesting capabilities. However, the unavoidable surface states of nanostructured materials create additional charge carrier trapping centers and energy barriers at the semiconductor-electrolyte interface, which severely reduce the solar-to-hydrogen conversion efficiency. In this work, we address the issue of surface states in GaN nanowire photoelectrodes by employing a simple and low-cost surface treatment method, which utilizes an organic thiol compound (i.e., 1,2-ethanedithiol). The surface-treated photocathode showed an enhanced photocurrent density of −31 mA/cm at −0.2 V versus RHE with an incident photon-to-current conversion efficiency of 18.3%, whereas untreated nanowires yielded only 8.1% efficiency. Furthermore, the surface passivation provides enhanced photoelectrochemical stability as surface-treated nanowires retained ∼80% of their initial photocurrent value and produced 8000 μmol of gas molecules over 55 h at acidic conditions (pH ∼ 0), whereas the untreated nanowires demonstrated only <4 h of photoelectrochemical stability. These findings shed new light on the importance of surface passivation of nanostructured photoelectrodes for photoelectrochemical applications.

  1. Bone surface enhancement in ultrasound images using a new Doppler-based acquisition/processing method

    Science.gov (United States)

    Yang, Xu; Tang, Songyuan; Tasciotti, Ennio; Righetti, Raffaella

    2018-01-01

    Ultrasound (US) imaging has long been considered as a potential aid in orthopedic surgeries. US technologies are safe, portable and do not use radiations. This would make them a desirable tool for real-time assessment of fractures and to monitor fracture healing. However, image quality of US imaging methods in bone applications is limited by speckle, attenuation, shadow, multiple reflections and other imaging artifacts. While bone surfaces typically appear in US images as somewhat ‘brighter’ than soft tissue, they are often not easily distinguishable from the surrounding tissue. Therefore, US imaging methods aimed at segmenting bone surfaces need enhancement in image contrast prior to segmentation to improve the quality of the detected bone surface. In this paper, we present a novel acquisition/processing technique for bone surface enhancement in US images. Inspired by elastography and Doppler imaging methods, this technique takes advantage of the difference between the mechanical and acoustic properties of bones and those of soft tissues to make the bone surface more easily distinguishable in US images. The objective of this technique is to facilitate US-based bone segmentation methods and improve the accuracy of their outcomes. The newly proposed technique is tested both in in vitro and in vivo experiments. The results of these preliminary experiments suggest that the use of the proposed technique has the potential to significantly enhance the detectability of bone surfaces in noisy ultrasound images.

  2. Surface plasmon enhancement in gold nanoparticles in the presence of an optical gain medium: an analysis

    Energy Technology Data Exchange (ETDEWEB)

    Sathiyamoorthy, K; Sreekanth, K V; Sidharthan, R; Murukeshan, V M [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Xing Bengang, E-mail: mmurukeshan@ntu.edu.sg [Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371 (Singapore)

    2011-10-26

    The localized surface plasmon (LSP) enhancement in a gold nanoparticle is demonstrated in this paper. The enhancement of LSP is influenced by both size and the dielectric gain medium surrounding the nanoparticles. The nanoparticle is found to induce plasmonic enhancement of varying degrees depending on its size, and it is inferred that a gold nanoparticle of size 60 nm exhibits the maximum LSP for 532 nm excitation. Singularity due to cancellation of SP loss by an infinite gain medium and LSP enhancement are studied using a pump-probe Rayleigh scattering experiment. Gold nanoparticles of average size 60 nm exhibit the lowest threshold power to observe Rayleigh scattering. Furthermore, compared with the bare nanoparticles, a 12.5 fold enhancement of LSP is observed when the nanoparticle of average size 60 nm is kept in the gain medium.

  3. Surface-enhanced Raman scattering on gold nanorod pairs with interconnection bars of different widths

    KAUST Repository

    Yue, Weisheng

    2012-08-01

    We demonstrate that surface-enhanced Raman scattering (SERS) enhancement could be tuned by adjusting the width of a connection bar at the bottom of a gold nanorod pair. Arrays of gold nanorod pairs with interconnection bars of different widths at the bottom of the interspace were fabricated by electron-beam lithography and used for the SERS study. Rhodamine 6G (R6G) was used as the probe molecule for the SERS. In addition to the large SERS enhancement observed in the nanostructured substrates, the SERS enhancement increases as the width of the connection bar increases. This result provides an important method for tuning SERS enhancement. Numerical simulations of electromagnetic properties on the nanostructures were performed with CST Microwave Studio, and the results correspond well with the experimental observations. © 2012 Elsevier B.V. All rights reserved.

  4. Surface-enhanced Raman scattering on periodic metal nanotips with tunable sharpness

    International Nuclear Information System (INIS)

    Linn, Nicholas C; Sun, C-H; Arya, Ajay; Jiang Peng; Jiang Bin

    2009-01-01

    This paper reports on a scalable bottom-up technology for producing periodic gold nanotips with tunable sharpness as surface-enhanced Raman scattering (SERS) substrates. Inverted silicon pyramidal pits, which are templated from non-close-packed colloidal crystals prepared by a spin-coating technology, are used as structural templates to replicate arrays of polymer nanopyramids with nanoscale sharp tips. The deposition of a thin layer of gold on the polymer nanopyramids leads to the formation of SERS-active substrates with a high enhancement factor (up to 10 8 ). The thickness of the deposited metal determines the sharpness of the nanotips and the resulting Raman enhancement factor. Finite-element electromagnetic modeling shows that the nanotips can significantly enhance the local electromagnetic field and the sharpness of nanotips greatly affects the SERS enhancement.

  5. Carbon-based nanostructured surfaces for enhanced phase-change cooling

    Science.gov (United States)

    Selvaraj Kousalya, Arun

    To maintain acceptable device temperatures in the new generation of electronic devices under development for high-power applications, conventional liquid cooling schemes will likely be superseded by multi-phase cooling solutions to provide substantial enhancement to the cooling capability. The central theme of the current work is to investigate the two-phase thermal performance of carbon-based nanostructured coatings in passive and pumped liquid-vapor phase-change cooling schemes. Quantification of the critical parameters that influence thermal performance of the carbon nanostructured boiling surfaces presented herein will lead to improved understanding of the underlying evaporative and boiling mechanisms in such surfaces. A flow boiling experimental facility is developed to generate consistent and accurate heat transfer performance curves with degassed and deionized water as the working fluid. New means of boiling heat transfer enhancement by altering surface characteristics such as surface energy and wettability through light-surface interactions is explored in this work. In this regard, carbon nanotube (CNT) coatings are exposed to low-intensity irradiation emitted from a light emitting diode and the subcooled flow boiling performance is compared against a non-irradiated CNT-coated copper surface. A considerable reduction in surface superheat and enhancement in average heat transfer coefficient is observed. In another work involving CNTs, the thermal performance of CNT-integrated sintered wick structures is evaluated in a passively cooled vapor chamber. A physical vapor deposition process is used to coat the CNTs with varying thicknesses of copper to promote surface wetting with the working fluid, water. Thermal performance of the bare sintered copper powder sample and the copper-functionalized CNT-coated sintered copper powder wick samples is compared using an experimental facility that simulates the capillary fluid feeding conditions of a vapor chamber

  6. Deep surface rolling for fatigue life enhancement of laser clad aircraft aluminium alloy

    Science.gov (United States)

    Zhuang, W.; Liu, Q.; Djugum, R.; Sharp, P. K.; Paradowska, A.

    2014-11-01

    Deep surface rolling can introduce deep compressive residual stresses into the surface of aircraft metallic structure to extend its fatigue life. To develop cost-effective aircraft structural repair technologies such as laser cladding, deep surface rolling was considered as an advanced post-repair surface enhancement technology. In this study, aluminium alloy 7075-T651 specimens with a blend-out region were first repaired using laser cladding technology. The surface of the laser cladding region was then treated by deep surface rolling. Fatigue testing was subsequently conducted for the laser clad, deep surface rolled and post-heat treated laser clad specimens. It was found that deep surface rolling can significantly improve the fatigue life in comparison with the laser clad baseline repair. In addition, three dimensional residual stresses were measured using neutron diffraction techniques. The results demonstrate that beneficial compressive residual stresses induced by deep surface rolling can reach considerable depths (more than 1.0 mm) below the laser clad surface.

  7. Biocompatibility enhancement of rare earth magnesium alloy by laser surface processing

    Science.gov (United States)

    Nie, Shilin; Wang, Yuqing; Liu, Haifeng; Guan, Yingchun

    2018-01-01

    Although magnesium and magnesium alloys are considered biocompatible and biodegradable, insufficient biocompatibility in body fluid environment is still the major drawback of magnesium alloys for their successful applications as biodegradable orthopaedic implants. In this work, magnesium alloy surface with both enhanced corrosion resistance and better cell adhesion property was directly fabricated by laser surface processing. Laser surface melting was used to improve corrosion resistance of Mg-6Gd-0.6Ca alloy. After laser surface melting, laser surface texturing was utilized on melted surface for better cell adhesion property. The corrosion resistance of laser-treated and as-received samples were evaluated using electrochemical technique. The effect of laser surface treatment on phase and microstructure evolution was evaluated using scanning electron microscopy, optical microscopy and X-ray diffraction. This work investigated the effect of laser treatment on cell distribution across the surface of magnesium alloy substrates. Osteoblast was cultured on the laser-treated surface and as-received surface. Cell morphology was observed with a scanning electron microscopy, and cell viability was evaluated by optical density measurement.

  8. Enhanced localization of Dyakonov-like surface waves in left-handed materials

    DEFF Research Database (Denmark)

    Crasovan, L. C.; Takayama, O.; Artigas, D.

    2006-01-01

    We address the existence and properties of hybrid surface waves forming at interfaces between left-handed materials and dielectric birefringent media. The existence conditions of such waves are found to be highly relaxed in comparison to Dyakonov waves existing in right-handed media. We show...... that left-handed materials cause the coexistence of several surface solutions, which feature an enhanced degree of localization. Remarkably, we find that the hybrid surface modes appear for large areas in the parameter space, a key property in view of their experimental observation....

  9. Peak quantification in surface-enhanced laser desorption/ionization by using mixture models

    NARCIS (Netherlands)

    Dijkstra, Martijn; Roelofsen, Han; Vonk, Roel J.; Jansen, Ritsert C.

    2006-01-01

    Surface-enhanced laser desorption/ionization (SELDI) time of flight (TOF) is a mass spectrometry technology for measuring the composition of a sampled protein mixture. A mass spectrum contains peaks corresponding to proteins in the sample. The peak areas are proportional to the measured

  10. NIR-FT Raman, FT-IR and surface-enhanced Raman scattering and ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 122; Issue 4. NIR-FT Raman, FT-IR and surface-enhanced Raman scattering and DFT based theoretical studies on the adsorption behaviour of (S)-Phenylsuccinic acid on silver nanoparticles. D Sajan V Bena Jothy Thomas Kuruvilla I Hubert Joe. Full Papers Volume ...

  11. Applicability of surface-enhanced resonance Raman scattering for the direct discrimination of ballpoint pen inks

    NARCIS (Netherlands)

    Seifar, R.M.; Verheul, J.M.; Ariese, F.; Brinkman, U.A.T.; Gooijer, C.

    2001-01-01

    In situ surface-enhanced resonance Raman spectroscopy (SERRS) with excitation at 685 nm is suitable for the direct discrimination of blue and black ballpoint pen inks on paper. For black inks, shorter excitation wavelengths can also be used. For blue inks, SERRS at 514.5 and 457.9 nm does not

  12. Surface-enhanced Raman scattering on aluminum using near infrared and visible excitation

    DEFF Research Database (Denmark)

    Mogensen, Klaus Bo; Gühlke, Marina; Kneipp, Janina

    2014-01-01

    We observed strong surface-enhanced Raman scattering on discontinuous nanostructured aluminum films using 785 nm excitation even though dielectric constants of this metal suggest plasmon supported spectroscopy in the ultraviolet range. The excitation of SERS correlates with plasmon resonances in ...... in the 1.3–2.5 eV range identified in electron energy loss spectra....

  13. Surface-enhanced resonance Raman spectroscopy as an identification tool in column liquid chromatography

    NARCIS (Netherlands)

    Seifar, R.M.; Altelaar, M.A.F.; Dijkstra, R.J.; Ariese, F.; Brinkman, U.A.T.; Gooijer, C.

    2000-01-01

    The compatibility of ion-pair reversed-phase column liquid chromatography and surface-enhanced resonance Raman spectroscopy (SERRS) for separation and identification of anionic dyes has been investigated, with emphasis on the at-line coupling via a thin-layer chromatography (TLC) plate. SERR spectra

  14. Mathematical model for biomolecular quantification using surface-enhanced Raman spectroscopy based signal intensity distributions

    DEFF Research Database (Denmark)

    Palla, Mirko; Bosco, Filippo Giacomo; Yang, Jaeyoung

    2015-01-01

    This paper presents the development of a novel statistical method for quantifying trace amounts of biomolecules by surface-enhanced Raman spectroscopy (SERS) using a rigorous, single molecule (SM) theory based mathematical derivation. Our quantification framework could be generalized for planar...

  15. Giant enhancement of sum-frequency yield by surface-plasmon excitation

    NARCIS (Netherlands)

    van der Ham, E. W. M.; Vrehen, Q. H. F.; Eliel, E. R.; Yakovlev, V. A.; Valieva, E. V.; Kuzik, L. A.; Petrov, J. E.; Sychugov, V. A.; van der Meer, A. F. G.

    1999-01-01

    We show experimentally that the radiation generated in infrared-visible sum-frequency mixing at an air-silver interface can be greatly enhanced when the visible input beam excites a surface plasmon-polariton at the interface. With either a prism or a grating used to couple the visible radiation with

  16. Heat Transfer Enhancement During Water and Hydrocarbon Condensation on Lubricant Infused Surfaces.

    Science.gov (United States)

    Preston, Daniel J; Lu, Zhengmao; Song, Youngsup; Zhao, Yajing; Wilke, Kyle L; Antao, Dion S; Louis, Marcel; Wang, Evelyn N

    2018-01-11

    Vapor condensation is routinely used as an effective means of transferring heat or separating fluids. Dropwise condensation, where discrete droplets form on the condenser surface, offers a potential improvement in heat transfer of up to an order of magnitude compared to filmwise condensation, where a liquid film covers the surface. Low surface tension fluid condensates such as hydrocarbons pose a unique challenge since typical hydrophobic condenser coatings used to promote dropwise condensation of water often do not repel fluids with lower surface tensions. Recent work has shown that lubricant infused surfaces (LIS) can promote droplet formation of hydrocarbons. In this work, we confirm the effectiveness of LIS in promoting dropwise condensation by providing experimental measurements of heat transfer performance during hydrocarbon condensation on a LIS, which enhances heat transfer by ≈450% compared to an uncoated surface. We also explored improvement through removal of noncondensable gases and highlighted a failure mechanism whereby shedding droplets depleted the lubricant over time. Enhanced condensation heat transfer for low surface tension fluids on LIS presents the opportunity for significant energy savings in natural gas processing as well as improvements in thermal management, heating and cooling, and power generation.

  17. Enhanced charge recombination due to surfaces and twin defects in GaAs nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Evan; Sheng, Chunyang; Nakano, Aiichiro [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States); Shimamura, Kohei; Shimojo, Fuyuki [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States); Department of Physics, Kumamoto University, Kumamoto 860-8555 (Japan)

    2015-02-07

    Power conversion efficiency of gallium arsenide (GaAs) nanowire (NW) solar cells is severely limited by enhanced charge recombination (CR) at sidewall surfaces, but its atomistic mechanisms are not well understood. In addition, GaAs NWs usually contain a high density of twin defects that form a twin superlattice, but its effects on CR dynamics are largely unknown. Here, quantum molecular dynamics (QMD) simulations reveal the existence of an intrinsic type-II heterostructure at the (110) GaAs surface. Nonadiabatic quantum molecular dynamics (NAQMD) simulations show that the resulting staggered band alignment causes a photoexcited electron in the bulk to rapidly transfer to the surface. We have found orders-of-magnitude enhancement of the CR rate at the surface compared with the bulk value. Furthermore, QMD and NAQMD simulations show unique surface electronic states at alternating (111)A and (111)B sidewall surfaces of a twinned [111]-oriented GaAs NW, which act as effective CR centers. The calculated large surface recombination velocity quantitatively explains recent experimental observations and provides microscopic understanding of the underlying CR processes.

  18. Photoluminescence enhancement of dye-doped nanoparticles by surface plasmon resonance effects of gold colloidal nanoparticles

    International Nuclear Information System (INIS)

    Chu, Viet Ha; Nghiem, Thi Ha Lien; Tran, Hong Nhung; Fort, Emmanuel

    2011-01-01

    Due to the energy transfer from surface plasmons, the fluorescence of fluorophores near metallic nanostructures can be enhanced. This effect has been intensively studied recently for biosensor applications. This work reports on the luminescence enhancement of 100 nm Cy3 dye-doped polystyrene nanoparticles by energy transfer from surface plasmons of gold colloidal nanoparticles with sizes of 20 and 100 nm. Optimal luminescence enhancement of the fluorophores has been observed in the mixture with 20 nm gold nanoparticles. This can be attributed to the resonance energy transfer from gold nanoparticles to the fluorophore beads. The interaction between the fluorophores and gold particles is attributed to far-field interaction

  19. Silver-coated Si nanograss as highly sensitive surface-enhanced Raman spectroscopy substrates

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Jing; Kuo, Huei Pei; Hu, Min; Li, Zhiyong; Williams, R.S. [Hewlett-Packard Laboratories, Information and Quantum Systems Laboratory, Palo Alto, CA (United States); Ou, Fung Suong [Hewlett-Packard Laboratories, Information and Quantum Systems Laboratory, Palo Alto, CA (United States); Rice University, Department of Applied Physics, Houston, TX (United States); Stickle, William F. [Hewlett-Packard Company, Advanced Diagnostic Lab, Corvallis, OR (United States)

    2009-09-15

    We created novel surface-enhanced Raman spectroscopy (SERS) substrates by metalization (Ag) of Si nanograss prepared by a Bosch process which involves deep reactive ion etching of single crystalline silicon. No template or lithography was needed for making the Si nanograss, thus providing a simple and inexpensive method to achieve highly sensitive large-area SERS substrates. The dependence of the SERS effect on the thickness of the metal deposition and on the surface morphology and topology of the substrate prior to metal deposition was studied in order to optimize the SERS signals. We observed that the Ag-coated Si nanograss can achieve uniform SERS enhancement over large area ({proportional_to}1 cm x 1 cm) with an average EF (enhancement factor) of 4.2 x 10{sup 8} for 4-mercaptophenol probe molecules. (orig.)

  20. O-(carboxymethyl)-chitosan nanofiltration membrane surface functionalized with graphene oxide nanosheets for enhanced desalting properties.

    Science.gov (United States)

    Wang, Jiali; Gao, Xueli; Wang, Jian; Wei, Yi; Li, Zhaokui; Gao, Congjie

    2015-02-25

    A novel O-(carboxymethyl)-chitosan (OCMC) nanofiltration (NF) membrane is developed via surface functionalization with graphene oxide (GO) nanosheets to enhance desalting properties. Using ring-opening polymerization between epoxy groups of GO nanosheets and amino groups of OCMC active layer, GO nanosheets are irreversibly bound to the membrane. The OCMC NF membranes surface-functionalized with GO nanosheets are characterized by Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy, contact angle analyzer, and zeta potential analyzer. The membranes exhibit not only higher permeability but also better salt rejections than the pristine membranes and the commercial NF membranes; besides, the desalting properties are enhanced with the concentration of GO nanosheets increasing. Furthermore, the transport mechanism of GO-OCMC NF membranes reveals that the nanoporous structure of GO-OCMC functional layer and size exclusion and electrostatic repulsion of water nanochannels formed by GO nanosheets lead to the membranes possessing enhanced desalting properties.

  1. Enhancement and suppression effects of a nanopatterned surface on bacterial adhesion

    Science.gov (United States)

    Li, Xinlei; Chen, Tongsheng

    2016-05-01

    We present a quantitative thermodynamic model to elucidate the effects of a nanopatterned surface on bacterial adhesion. Based on the established model, we studied the equilibrium state of rodlike bacterial cells adhered to a nanopillar-patterned surface. Theoretical analyses showed the physical origin of bacterial adhesion on a nanopatterned surface is actually determined by the balance between adhesion energy and deformation energy of the cell membrane. We found that there are enhancement effects on bacterial adhesion to the patterned surface with large radius and small spacing of nanopillars, but suppression effects for nanopillars with a radius smaller than a critical value. In addition, according to our model, a phase diagram has been constructed which can clarify the interrelated effects of the radius and the spacing of nanopillars. The broad agreement with experimental observations implies that these studies would provide useful guidance to the design of nanopatterned surfaces for biomedical applications.

  2. Enhancing the formation and shear resistance of nitrifying biofilms on membranes by surface modification

    DEFF Research Database (Denmark)

    Lackner, Susanne; Holmberg, Maria; Terada, Akihiko

    2009-01-01

    Polypropylene (PP) membranes and polyethylene (PE) surfaces were modified to enhance formation and shear resistance of nitrifying biofilms for wastewater treatment applications. A combination of plasma polymerization and wet chemistry was employed to ultimately introduce poly(ethyleneglycol) (PEG...... structure might be possible explanations of the superiority of the -PEG-NH2 modification. The success of the-PEG-NH2 modification was independent of the original surface and might, therefore, be used in wastewater treatment bioreactors to improve reactor performance by making biofilm formation more stable...... similar trends: biofilms on -PEG-NH2 modified surfaces were much stronger compared to the other modifications and the unmodified reference surfaces. Electrostatic interactions between the protonated amino group and negatively charged bacteria as well as PEG chain density which can affect the surface...

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

    Science.gov (United States)

    Janesko, Benjamin G; Scuseria, Gustavo E

    2006-09-28

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

  4. Periodic array-based substrates for surface-enhanced infrared spectroscopy

    Directory of Open Access Journals (Sweden)

    Mayerhöfer Thomas G.

    2018-01-01

    Full Text Available At the beginning of the 1980s, the first reports of surface-enhanced infrared spectroscopy (SEIRS surfaced. Probably due to signal-enhancement factors of only 101 to 103, which are modest compared to those of surface-enhanced Raman spectroscopy (SERS, SEIRS did not reach the same significance up to date. However, taking the compared to Raman scattering much larger cross-sections of infrared absorptions and the enhancement factors together, SEIRS reaches about the same sensitivity for molecular species on a surface in terms of the cross-sections as SERS and, due to the complementary nature of both techniques, can valuably augment information gained by SERS. For the first 20 years since its discovery, SEIRS relied completely on metal island films, fabricated by either vapor or electrochemical deposition. The resulting films showed a strong variance concerning their structure, which was essentially random. Therefore, the increase in the corresponding signal-enhancement factors of these structures stagnated in the last years. In the very same years, however, the development of periodic array-based substrates helped SEIRS to gather momentum. This development was supported by technological progress concerning electromagnetic field solvers, which help to understand plasmonic properties and allow targeted design. In addition, the strong progress concerning modern fabrication methods allowed to implement these designs into practice. The aim of this contribution is to critically review the development of these engineered surfaces for SEIRS, to compare the different approaches with regard to their performance where possible, and report further gain of knowledge around and in relation to these structures.

  5. Laser writing of single-crystalline gold substrates for surface enhanced Raman spectroscopy

    Science.gov (United States)

    Singh, Astha; Sharma, Geeta; Ranjan, Neeraj; Mittholiya, Kshitij; Bhatnagar, Anuj; Singh, B. P.; Mathur, Deepak; Vasa, Parinda

    2017-07-01

    Surface enhanced Raman scattering (SERS) spectroscopy, a powerful contemporary tool for studying low-concentration analytes via surface plasmon induced enhancement of local electric field, is of utility in biochemistry, material science, threat detection, and environmental studies. We have developed a simple, fast, scalable, and relatively low-cost optical method of fabricating and characterizing large-area, reusable and broadband SERS substrates with long storage lifetime. We use tightly focused, intense infra-red laser pulses to write gratings on single-crystalline, Au (1 1 1) gold films on mica which act as SERS substrates. Our single-crystalline SERS substrates compare favourably, in terms of surface quality and roughness, to those fabricated in poly-crystalline Au films. Tests show that our SERS substrates have the potential of detecting urea and 1,10-phenantroline adulterants in milk and water, respectively, at 0.01 ppm (or lower) concentrations.

  6. Surface-Enhanced Raman Spectroelectrochemistry of TTF-Modified Self-Assembled Monolayers.

    Science.gov (United States)

    Paxton, Walter F; Kleinman, Samuel L; Basuray, Ashish N; Stoddart, J Fraser; Van Duyne, Richard P

    2011-05-19

    Surface-enhanced Raman spectroscopy (SERS) was used to monitor the response of a self-assembled monolayer (SAM) of a tetrathiafulvalene (TTF) derivative on a gold film-over-nanosphere electrode. The electrochemical response observed was rationalized in terms of the interactions between TTF moieties as the oxidation state was changed. Electrochemical oxidation to form the monocation caused the absorbance of the TTF unit to coincide with both the laser excitation wavelength and the localized surface plasmon resonance (LSPR), resulting in surface-enhanced resonance Raman scattering (SERRS). The vibrational frequency changes that accompany electron transfer afford a high-contrast mechanism that can be used to determine the oxidation state of the TTF unit in an unambiguous manner.

  7. Environmentally responsive surface-modified silica nanoparticles for enhanced oil recovery

    International Nuclear Information System (INIS)

    Behzadi, Abed; Mohammadi, Aliasghar

    2016-01-01

    Environmentally responsive surface-modified nanoparticles are colloidal nanoparticles coated with, at least, two physicochemically distinct surface groups. Recent advances in the synthesis and production of nanoparticles have enabled the production of environmentally responsive surface-modified nanoparticles with both hydrophilic and hydrophobic surface groups. These nanoparticles act like colloidal surfactants. In this paper, environmentally responsive surface-modified silica nanoparticles are synthesized and used for enhancement of oil recovery. For this purpose, silica nanoparticles are coated with polyethylene glycol chains as hydrophilic agent and propyl chains as hydrophobic agent at various quantities, and their ability to modulate oil–water interface properties and oil recovery is examined. Oil–water interfacial tension and water surface tension are decreased by 50 % in the presence of silica nanoparticles coated with both agents. Measuring oil-drop contact angle on oil-wetted glass slides and carbonate rock sections, after aging in various surface-modified silica nanofluids, indicates that the wettability of various oil-wetted surfaces is modified from strongly oil-wet to water-wet. Flooding nanofluids to glass micro-models and pore-level investigations demonstrate that surface modification of silica nanoparticles, specially, with both hydrophilic and hydrophobic agents improves considerably their performance in increasing oil recovery and wettability alteration.

  8. Attenuating Immune Response of Macrophage by Enhancing Hydrophilicity of Ti Surface

    Directory of Open Access Journals (Sweden)

    Xiaohan Dai

    2015-01-01

    Full Text Available Immune responses can determine the in vivo fate of implanted materials. The strategy for developing implants has shifted towards using materials with immunomodulatory activity. However, the immunoregulatory effect of hydrophilicity of titanium surface on the macrophage behavior and its underlying mechanism remain poorly understood. Here, the Ti surface hydrophilicity-dependent behavior of murine RAW264.7 macrophages was investigated in vitro. Two laboratory models with significantly different surface hydrophilicity and similar roughness were established with Ti-polished and Ti-H2O2 surfaces. The results of cell morphology observation showed that the Ti-H2O2 surface yielded enhanced cell adhesion and less multinucleated cell formation. CCK-8 assay indicated that the growth rate of macrophage on Ti-H2O2 surface is higher than that of Ti-polished. ELISA assay result revealed lower level of proinflammatory factor TNF-α and higher level of anti-inflammatory factor IL-10 on the Ti-H2O2 surface compared to Ti-polished. Subsequently, immunofluorescence and western blotting analysis showed that activation of the NF-κB-TNF-α pathway might be involved in the modulation of the immune response by surface hydrophilicity. Together, these results suggested that relative high hydrophilic Ti surface might attenuate the immune response of macrophage by activating NF-κB signaling. These findings could provide new insights into designing implant devices for orthopedic applications.

  9. Environmentally responsive surface-modified silica nanoparticles for enhanced oil recovery

    Energy Technology Data Exchange (ETDEWEB)

    Behzadi, Abed; Mohammadi, Aliasghar, E-mail: amohammadi@sharif.edu [Sharif University of Technology, Department of Chemical and Petroleum Engineering (Iran, Islamic Republic of)

    2016-09-15

    Environmentally responsive surface-modified nanoparticles are colloidal nanoparticles coated with, at least, two physicochemically distinct surface groups. Recent advances in the synthesis and production of nanoparticles have enabled the production of environmentally responsive surface-modified nanoparticles with both hydrophilic and hydrophobic surface groups. These nanoparticles act like colloidal surfactants. In this paper, environmentally responsive surface-modified silica nanoparticles are synthesized and used for enhancement of oil recovery. For this purpose, silica nanoparticles are coated with polyethylene glycol chains as hydrophilic agent and propyl chains as hydrophobic agent at various quantities, and their ability to modulate oil–water interface properties and oil recovery is examined. Oil–water interfacial tension and water surface tension are decreased by 50 % in the presence of silica nanoparticles coated with both agents. Measuring oil-drop contact angle on oil-wetted glass slides and carbonate rock sections, after aging in various surface-modified silica nanofluids, indicates that the wettability of various oil-wetted surfaces is modified from strongly oil-wet to water-wet. Flooding nanofluids to glass micro-models and pore-level investigations demonstrate that surface modification of silica nanoparticles, specially, with both hydrophilic and hydrophobic agents improves considerably their performance in increasing oil recovery and wettability alteration.

  10. Environmentally responsive surface-modified silica nanoparticles for enhanced oil recovery

    Science.gov (United States)

    Behzadi, Abed; Mohammadi, Aliasghar

    2016-09-01

    Environmentally responsive surface-modified nanoparticles are colloidal nanoparticles coated with, at least, two physicochemically distinct surface groups. Recent advances in the synthesis and production of nanoparticles have enabled the production of environmentally responsive surface-modified nanoparticles with both hydrophilic and hydrophobic surface groups. These nanoparticles act like colloidal surfactants. In this paper, environmentally responsive surface-modified silica nanoparticles are synthesized and used for enhancement of oil recovery. For this purpose, silica nanoparticles are coated with polyethylene glycol chains as hydrophilic agent and propyl chains as hydrophobic agent at various quantities, and their ability to modulate oil-water interface properties and oil recovery is examined. Oil-water interfacial tension and water surface tension are decreased by 50 % in the presence of silica nanoparticles coated with both agents. Measuring oil-drop contact angle on oil-wetted glass slides and carbonate rock sections, after aging in various surface-modified silica nanofluids, indicates that the wettability of various oil-wetted surfaces is modified from strongly oil-wet to water-wet. Flooding nanofluids to glass micro-models and pore-level investigations demonstrate that surface modification of silica nanoparticles, specially, with both hydrophilic and hydrophobic agents improves considerably their performance in increasing oil recovery and wettability alteration.

  11. Smooth, All-Solid, Low-Hysteresis, Omniphobic Surfaces with Enhanced Mechanical Durability.

    Science.gov (United States)

    Boban, Mathew; Golovin, Kevin; Tobelmann, Brian; Gupte, Omkar; Mabry, Joseph M; Tuteja, Anish

    2018-03-19

    The utility of omniphobic surfaces stems from their ability to repel a multitude of liquids, possessing a broad range of surface tensions and polarities, by causing them to bead up and either roll or slide off. These surfaces may be self-cleaning, corrosion-resistant, heat-transfer enhancing, stain-resistant or resistant to mineral- or bio-fouling. The majority of reported omniphobic surfaces use texture, lubricants, and/or grafted monolayers to engender these repellent properties. Unfortunately, these approaches often produce surfaces with deficiencies in long-term stability, durability, scalability, or applicability to a wide range of substrates. To overcome these limitations, we have fabricated an all-solid, substrate-independent, smooth, omniphobic coating composed of a fluorinated polyurethane and fluorodecyl polyhedral oligomeric silsesquioxane. Liquids of varying surface tension, including water, hexadecane, ethanol, and silicone oil, exhibit low contact angle hysteresis (< 15°) on these surfaces, allowing liquid droplets to slide off, leaving no residue. Moreover, we demonstrate that these robust surfaces retained their repellent properties more effectively than textured or lubricated omniphobic surfaces after being subjected to mechanical abrasion.

  12. U.S. Navy Surface Ship Fleet: Propulsion Energy Evaluation, and Identification of Cost Effective Energy Enhancement Devices

    National Research Council Canada - National Science Library

    Cusanelli, Dominic S; Karafiath, Gabor

    2006-01-01

    .... Navy surface ship fleet was prepared. This information was used to identify eleven U.S. Navy surface ship classes as candidates for consideration with regard to retrofit of energy enhancement devices...

  13. Gold nanoparticle dimer plasmonics: finite element method calculations of the electromagnetic enhancement to surface-enhanced Raman spectroscopy.

    Science.gov (United States)

    McMahon, Jeffrey M; Henry, Anne-Isabelle; Wustholz, Kristin L; Natan, Michael J; Freeman, R Griffith; Van Duyne, Richard P; Schatz, George C

    2009-08-01

    Finite element method calculations were carried out to determine extinction spectra and the electromagnetic (EM) contributions to surface-enhanced Raman spectroscopy (SERS) for 90-nm Au nanoparticle dimers modeled after experimental nanotags. The calculations revealed that the EM properties depend significantly on the junction region, specifically the distance between the nanoparticles for spacings of less than 1 nm. For extinction spectra, spacings below 1 nm lead to maxima that are strongly red-shifted from the 600-nm plasmon maximum associated with an isolated nanoparticle. This result agrees qualitatively well with experimental transmission electron microscopy images and localized surface plasmon resonance spectra that are also presented. The calculations further revealed that spacings below 0.5 nm, and especially a slight fusing of the nanoparticles to give tiny crevices, leads to EM enhancements of 10(10) or greater. Assuming a uniform coating of SERS molecules around both nanoparticles, we determined that regardless of the separation, the highest EM fields always dominate the SERS signal. In addition, we determined that for small separations less than 3% of the molecules always contribute to greater than 90% of the signal.

  14. Two-Dimensional Titanium Carbide (MXene) as Surface-Enhanced Raman Scattering Substrate

    Energy Technology Data Exchange (ETDEWEB)

    Sarycheva, Asia [Drexel Univ., Philadelphia, PA (United States); Makaryan, Taron [Drexel Univ., Philadelphia, PA (United States); Maleski, Kathleen [Drexel Univ., Philadelphia, PA (United States); Satheeshkumar, Elumalai [National Cheng Kung Univ., Tainan (Taiwan); National Institute of Technology-Trichy, Tamil Nadu (India); Melikyan, Armen [Russian-Armenian (Slavonic) State Univ., Yerevan (Armenia); Minassian, Hayk [A. Alikhanian National Science Lab., Yerevan (Armenia); Yoshimura, Masahiro [National Cheng Kung Univ., Tainan (Taiwan); Gogotsi, Yury G. [Drexel Univ., Philadelphia, PA (United States)

    2017-08-22

    Here, noble metal (gold or silver) nanoparticles or patterned films are typically used as substrates for surface-enhanced Raman spectroscopy (SERS). Two-dimensional (2D) carbides and nitrides (MXenes) exhibit unique electronic and optical properties, including metallic conductivity and plasmon resonance in the visible or near-infrared range, making them promising candidates for a wide variety of applications. Herein, we show that 2D titanium carbide, Ti3C2Tx, enhances Raman signal from organic dyes on a substrate and in solution. As a proof of concept, MXene SERS substrates were manufactured by spray-coating and used to detect several common dyes, with calculated enhancement factors reaching ~106. Titanium carbide MXene demonstrates SERS effect in aqueous colloidal solutions, suggesting the potential for biomedical or environmental applications, where MXene can selectively enhance positively charged molecules.

  15. Multi-metal, Multi-wavelength Surface-Enhanced Raman Spectroscopy Detection of Neurotransmitters.

    Science.gov (United States)

    Moody, Amber S; Sharma, Bhavya

    2018-04-05

    The development of a sensor for the rapid and sensitive detection of neurotransmitters could provide a pathway for the diagnosis of neurological diseases, leading to the discovery of more effective treatment methods. We investigate the use of surface enhanced Raman spectroscopy (SERS) based sensors for the rapid detection of melatonin, serotonin, glutamate, dopamine, GABA, norepinephrine, and epinephrine. Previous studies have demonstrated SERS detection of neurotransmitters; however, there has been no comprehensive study on the effect of the metal used as the SERS substrate or the excitation wavelength used for detection. Here, we present the detection of 7 neurotransmitters using both silver and gold nanoparticles at excitation wavelengths of 532, 633, and 785 nm. Over the range of wavelengths investigated, the SERS enhancement on the silver and gold nanoparticles varies, with an average enhancement factor of 10 5 -10 6 . The maximum SERS enhancement occurs at an excitation wavelength of 785 nm for the gold nanoparticles and at 633 nm for the silver nanoparticles.

  16. Secondary ion mass spectrometric signal enhancement of phosphatidylcholine dioleoyl on enlarged nanoparticles surface

    Science.gov (United States)

    Gulin, A.; Mochalova, M.; Denisov, N.; Nadtochenko, V.

    2014-10-01

    A silicon wafer surface coverage of nanoparticles (NPs) can enhance the L-α-phosphatidylcholine dioleoyl (DOPC) signal intensity in time-of-flight secondary ion mass spectrometry (TOF-SIMS). A ToF-SIMS mass spectrometer was used with a pulsed primary beam of focused 30 keV Bi3+ ions. The signal enhancing effect has been studied for metallic (Ag, Au, Pb), semiconductor (TiO2), dielectric (SiO2) and hybrid (Au/TiO2NPs, core-shell Au/SiO2) nanoparticles. Ag NPs can attenuate secondary ions signal, whereas all other studied NPs show the signal enhancement. The emission of DOPC lipid secondary ions immobilized on core-shell Au/SiO2NPs was enhanced up to 42 times. This technique is a simple preparatory method enabling an overall increase in molecular lipid ions.

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

    Science.gov (United States)

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

    2015-05-01

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

  18. Enhanced adhesion of osteoblastic cells on polystyrene films by independent control of surface topography and wettability

    International Nuclear Information System (INIS)

    Yang, Seung Yun; Kim, Eung-Sam; Jeon, Gumhye; Choi, Kwan Yong; Kim, Jin Kon

    2013-01-01

    We independently controlled surface topography and wettability of polystyrene (PS) films by CF 4 and oxygen plasma treatments, respectively, to evaluate the adhesion and proliferation of human fetal osteoblastic (hFOB) cells on the films. Among the CF 4 plasma-treated PS films with the average surface roughness ranging from 0.9 to 70 nm, the highest adhesion of hFOB cells was observed on a PS film with roughness of ∼ 11 nm. When this film was additionally treated by oxygen plasma to provide a hydrophilic surface with a contact angle less than 10°, the proliferation of bone-forming cell was further enhanced. Thus, the plasma-based independent modification of PS film into an optimum nanotexture for human osteoblast cells could be appplied to materials used in bone tissue engineering. Highlights: ► New approach based on plasma treatment to independently control the surface topography and wettability ► The adhesion of human fetal osteoblast (hFOB) was enhanced on a surface with an average roughness of ∼ 11 nm. ► The adhesion and proliferation of hFOB was maximized when nanotextured surface became highly hydrophilic

  19. Optical coherence refractometry.

    Science.gov (United States)

    Tomlins, Peter H; Woolliams, Peter; Hart, Christian; Beaumont, Andrew; Tedaldi, Matthew

    2008-10-01

    We introduce a novel approach to refractometry using a low coherence interferometer at multiple angles of incidence. We show that for plane parallel samples it is possible to measure their phase refractive index rather than the group index that is usually measured by interferometric methods. This is a significant development because it enables bulk refractive index measurement of scattering and soft samples, not relying on surface measurements that can be prone to error. Our technique is also noncontact and compatible with in situ refractive index measurements. Here, we demonstrate this new technique on a pure silica test piece and a highly scattering resin slab, comparing the results with standard critical angle refractometry.

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

    Science.gov (United States)

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

    2017-08-25

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

  1. Mussel-inspired superhydrophobic surfaces with enhanced corrosion resistance and dual-action antibacterial properties.

    Science.gov (United States)

    Qian, Hongchang; Li, Minglu; Li, Zhong; Lou, Yuntian; Huang, Luyao; Zhang, Dawei; Xu, Dake; Du, Cuiwei; Lu, Lin; Gao, Jin

    2017-11-01

    In this study, a multilayer antibacterial film was assembled onto 316L stainless steel via mussel-inspired depositions of polydopamine (PDA) and silver (Ag) nanoparticles followed by post-modification with 1H, 1H, 2H, 2H-perfluorodecanethiol. The resulting surface exhibited excellent superhydrophobicity with hierarchical micro/nanostructures that were constructed by both PDA and Ag nanoparticles. The crystal structure and chemical composition of these surfaces were investigated using X-ray photoelectron spectroscopy (XPS) analysis. Potentiodynamic polarization measurements revealed that the corrosion resistance of the as-prepared surfaces were sequentially increased after each step of the fabrication process. Compared with the surface covered with only Ag nanoparticles, the superhydrophobic surfaces exhibited substantially enhanced antibacterial activity against the Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus, resulting from the synergistic antibacterial actions of the superhydrophobic surface and Ag nanoparticles. The superhydrophobic surface exhibited lower cytotoxicity, compared to the surface covered with Ag nanoparticles. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Enhanced in vitro biocompatibility of ultrafine-grained titanium with hierarchical porous surface

    International Nuclear Information System (INIS)

    Zheng, C.Y.; Nie, F.L.; Zheng, Y.F.; Cheng, Y.; Wei, S.C.; Valiev, R.Z.

    2011-01-01

    Bulk ultrafine-grained Ti (UFG Ti) was successfully fabricated by equal-channel angular pressing (ECAP) technique in the present study, and to further improve its surface biocompatibility, surface modification techniques including sandblasting, acid etching and alkali treatment were employed to produce a hierarchical porous surface. The effect of the above surface treatments on the surface roughness, wettability, electrochemical corrosion behavior, apatite forming ability and cellular behavior of UFG Ti were systematically investigated with the coarse-grained Ti as control. Results show that UFG-Ti with surface modification had no pitting corrosion and presented low corrosion rate in simulated body fluids (SBF). The hierarchical porous surface yielded by surface modification enhanced the ability of UFG Ti to form a complete apatite layer when soaked in SBF and promoted osteoblast-like cells attachment and proliferation in vitro, which promises to have a significant impact on increasing bone-bonding ability and reducing healing time when implanted due to faster tissue integration.

  3. Grafting zwitterionic polymer onto cryogel surface enhances protein retention in steric exclusion chromatography on cryogel monolith.

    Science.gov (United States)

    Tao, Shi-Peng; Zheng, Jie; Sun, Yan

    2015-04-10

    Cryogel monoliths with interconnected macropores (10-100μm) and hydrophilic surfaces can be employed as chromatography media for protein retention in steric exclusion chromatography (SXC). SXC is based on the principle that the exclusion of polyethylene glycol (PEG) on both a hydrophilic chromatography surface and a protein favors their association, leading to the protein retention on the chromatography surface. Elution of the retained protein can be achieved by reducing PEG concentration. In this work, the surface of polyacrylamide-based cryogel monolith was modified by grafting zwitterionic poly(carboxybetaine methacrylate) (pCBMA), leading the increase in the surface hydrophilicity. Observation by scanning electron microscopy revealed the presence of the grafted pCBMA chain clusters on the cryogel surface, but pCBMA grafting did not result in the changes of the physical properties of the monolith column, and the columns maintained good recyclability in SXC. The effect of the surface grafting on the SXC behavior of γ-globulin was investigated in a wide flow rate range (0.6-12cm/min). It was found that the dynamic retention capacity increased 1.4-1.8 times by the zwitterionic polymer grafting in the flow rate range of 1.5-12cm/min. The mechanism of enhanced protein retention on the zwitterionic polymer-grafted surface was proposed. The research proved that zwitterionic polymer modification was promising for the development of new materials for SXC applications. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Evolution of interfacial intercalation chemistry on epitaxial graphene/SiC by surface enhanced Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ferralis, Nicola, E-mail: ferralis@mit.edu [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Carraro, Carlo [Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA 94720 (United States)

    2014-11-30

    Highlights: • H-intercalated epitaxial graphene–SiC interface studied with surface enhanced Raman. • Evolution of graphene and H–Si interface with UV-ozone, annealing and O-exposure. • H–Si interface and quasi-freestanding graphene are retained after UV-ozone treatment. • Enhanced ozonolytic reactivity at the edges of H-intercalated defected graphene. • Novel SERS method for characterizing near-surface graphene–substrate interfaces. - Abstract: A rapid and facile evaluation of the effects of physical and chemical processes on the interfacial layer between epitaxial graphene monolayers on SiC(0 0 0 1) surfaces is essential for applications in electronics, photonics, and optoelectronics. Here, the evolution of the atomic scale epitaxial graphene-buffer-layer–SiC interface through hydrogen intercalation, thermal annealings, UV-ozone etching and oxygen exposure is studied by means of single microparticle mediated surface enhanced Raman spectroscopy (smSERS). The evolution of the interfacial chemistry in the buffer layer is monitored through the Raman band at 2132 cm{sup −1} corresponding to the Si-H stretch mode. Graphene quality is monitored directly by the selectively enhanced Raman signal of graphene compared to the SiC substrate signal. Through smSERS, a simultaneous correlation between optimized hydrogen intercalation in epitaxial graphene/SiC and an increase in graphene quality is uncovered. Following UV-ozone treatment, a fully hydrogen passivated interface is retained, while a moderate degradation in the quality of the hydrogen intercalated quasi-freestanding graphene is observed. While hydrogen intercalated defect free quasi-freestanding graphene is expected to be robust upon UV-ozone, thermal annealing, and oxygen exposure, ozonolytic reactivity at the edges of H-intercalated defected graphene results in enhanced amorphization of the quasi-freestanding (compared to non-intercalated) graphene, leading ultimately to its complete etching.

  5. Evolution of interfacial intercalation chemistry on epitaxial graphene/SiC by surface enhanced Raman spectroscopy

    International Nuclear Information System (INIS)

    Ferralis, Nicola; Carraro, Carlo

    2014-01-01

    Highlights: • H-intercalated epitaxial graphene–SiC interface studied with surface enhanced Raman. • Evolution of graphene and H–Si interface with UV-ozone, annealing and O-exposure. • H–Si interface and quasi-freestanding graphene are retained after UV-ozone treatment. • Enhanced ozonolytic reactivity at the edges of H-intercalated defected graphene. • Novel SERS method for characterizing near-surface graphene–substrate interfaces. - Abstract: A rapid and facile evaluation of the effects of physical and chemical processes on the interfacial layer between epitaxial graphene monolayers on SiC(0 0 0 1) surfaces is essential for applications in electronics, photonics, and optoelectronics. Here, the evolution of the atomic scale epitaxial graphene-buffer-layer–SiC interface through hydrogen intercalation, thermal annealings, UV-ozone etching and oxygen exposure is studied by means of single microparticle mediated surface enhanced Raman spectroscopy (smSERS). The evolution of the interfacial chemistry in the buffer layer is monitored through the Raman band at 2132 cm −1 corresponding to the Si-H stretch mode. Graphene quality is monitored directly by the selectively enhanced Raman signal of graphene compared to the SiC substrate signal. Through smSERS, a simultaneous correlation between optimized hydrogen intercalation in epitaxial graphene/SiC and an increase in graphene quality is uncovered. Following UV-ozone treatment, a fully hydrogen passivated interface is retained, while a moderate degradation in the quality of the hydrogen intercalated quasi-freestanding graphene is observed. While hydrogen intercalated defect free quasi-freestanding graphene is expected to be robust upon UV-ozone, thermal annealing, and oxygen exposure, ozonolytic reactivity at the edges of H-intercalated defected graphene results in enhanced amorphization of the quasi-freestanding (compared to non-intercalated) graphene, leading ultimately to its complete etching

  6. Broadband enhancement of photoluminance from colloidal metal halide perovskite nanocrystals on plasmonic nanostructured surfaces.

    Science.gov (United States)

    Zhang, Si; Liang, Yuzhang; Jing, Qiang; Lu, Zhenda; Lu, Yanqing; Xu, Ting

    2017-11-07

    Metal halide perovskite nanocrystals (NCs) as a new kind of promising optoelectronic material have attracted wide attention due to their high photoluminescence (PL) quantum yield, narrow emission linewidth and wideband color tunability. Since the PL intensity always has a direct influence on the performance of optoelectronic devices, it is of vital importance to improve the perovskite NCs' fluorescence emission efficiency. Here, we synthesize three inorganic perovskite NCs and experimentally demonstrate a broadband fluorescence enhancement of perovskite NCs by exploiting plasmonic nanostructured surface consisting of nanogrooves array. The strong near-field optical localization associated with surface plasmon polariton-coupled emission effect generated by the nanogrooves array can significantly boost the absorption of perovskite NCs and tailor the fluorescence emissions. As a result, the PL intensities of perovskite NCs are broadband enhanced with a maximum factor higher than 8-fold achieved in experimental demonstration. Moreover, the high efficiency PL of perovskite NCs embedded in the polymer matrix layer on the top of plasmonic nanostructured surface can be maintained for more than three weeks. These results imply that plasmonic nanostructured surface is a good candidate to stably broadband enhance the PL intensity of perovskite NCs and further promote their potentials in the application of visible-light-emitting devices.

  7. Sensitive Detection of Biomolecules by Surface Enhanced Raman Scattering using Plant Leaves as Natural Substrates

    Directory of Open Access Journals (Sweden)

    Sharma Vipul

    2017-01-01

    Full Text Available Detection of biomolecules is highly important for biomedical and other biological applications. Although several methods exist for the detection of biomolecules, surface enhanced Raman scattering (SERS has a unique role in greatly enhancing the sensitivity. In this work, we have demonstrated the use of natural plant leaves as facile, low cost and eco-friendly SERS substrates for the sensitive detection of biomolecules. Specifically, we have investigated the influence of surface topography of five different plant leaf based substrates, deposited with Au, on the SERS performance by using L-cysteine as a model biomolecule. In addition, we have also compared the effect of sputter deposition of Au thin film with dropcast deposition of Au nanoparticles on the leaf substrates. Our results indicate that L-cysteine could be detected with high sensitivity using these plant leaf based substrates and the leaf possessing hierarchical micro/nanostructures on its surface shows higher SERS enhancement compared to a leaf having a nearplanar surface. Furthermore, leaves with drop-casted Au nanoparticle clusters performed better than the leaves sputter deposited with a thin Au film.

  8. Enhanced compatibility of chemically modified titanium surface with periodontal ligament cells

    Energy Technology Data Exchange (ETDEWEB)

    Kado, T.; Hidaka, T. [Division of Periodontology and Endodontology, Department of Oral Rehabilitation, School of Dentistry, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido 061-0293 (Japan); Aita, H. [Division of Occlusion and Removable Prosthodontics, Department of Oral Rehabilitation, School of Dentistry, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido 061-0293 (Japan); Endo, K. [Division of Biomaterials and Bioengineering, Department of Oral Rehabilitation, School of Dentistry, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido 061-0293 (Japan); Furuichi, Y., E-mail: furuichi@hoku-iryo-u.ac.jp [Division of Periodontology and Endodontology, Department of Oral Rehabilitation, School of Dentistry, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido 061-0293 (Japan)

    2012-12-01

    Highlights: Black-Right-Pointing-Pointer Cell-adhesive molecules were covalently immobilized on a Ti surface. Black-Right-Pointing-Pointer Immobilized cell-adhesive molecules maintained native function on the Ti surface. Black-Right-Pointing-Pointer Immobilized collagen enhanced adhesion of periodontal ligament cells to the Ti. - Abstract: A simple chemical modification method was developed to immobilize cell-adhesive molecules on a titanium surface to improve its compatibility with human periodontal ligament cells (HPDLCs).The polished titanium disk was immersed in 1% (v/v) p-vinylbenzoic acid solution for 2 h to introduce carboxyl groups onto the surface. After rinsing with distilled deionized water, the titanium disk was dipped into 1.47% 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide solution containing 0.1 mg/ml Gly-Arg-Gly-Asp-Ser (GRGDS), human plasma fibronectin (pFN), or type I collagen from calf skin (Col) to covalently immobilize the cell-adhesive molecules on the titanium surface via formation of peptide bonds. X-ray photoelectron spectroscopy analyses revealed that cell-adhesive molecules were successfully immobilized on the titanium surfaces. The Col-immobilized titanium surface revealed higher values regarding nano rough characteristics than the as-polished titanium surface under scanning probe microscopy. The number of HPDLCs attached to both the pFN- and Col-immobilized titanium surfaces was twice that attached to the as-polished titanium surfaces. The cells were larger with the cellular processes that stretched to a greater extent on the pFN- and Col-immobilized titanium surfaces than on the as-polished titanium surface (p < 0.05). HPDLCs on the Col-immobilized titanium surfaces showed more extensive expression of vinculin at the tips of cell projections and more contiguously along the cell outline than on the as-polished, GRGDS-immobilized and pFN-immobilized titanium surfaces. It was concluded that cell-adhesive molecules successfully

  9. Aluminum Film-Over-Nanosphere Substrates for Deep-UV Surface-Enhanced Resonance Raman Spectroscopy.

    Science.gov (United States)

    Sharma, Bhavya; Cardinal, M Fernanda; Ross, Michael B; Zrimsek, Alyssa B; Bykov, Sergei V; Punihaole, David; Asher, Sanford A; Schatz, George C; Van Duyne, Richard P

    2016-12-14

    We report here the first fabrication of aluminum film-over nanosphere (AlFON) substrates for UV surface-enhanced resonance Raman scattering (UVSERRS) at the deepest UV wavelength used to date (λ ex = 229 nm). We characterize the AlFONs fabricated with two different support microsphere sizes using localized surface plasmon resonance spectroscopy, electron microscopy, SERRS of adenine, tris(bipyridine)ruthenium(II), and trans-1,2-bis(4-pyridyl)-ethylene, SERS of 6-mercapto-1-hexanol (as a nonresonant molecule), and dielectric function analysis. We find that AlFONs fabricated with the 210 nm microspheres generate an enhancement factor of approximately 10 4-5 , which combined with resonance enhancement of the adsorbates provides enhancement factors greater than 10 6 . These experimental results are supported by theoretical analysis of the dielectric function. Hence our results demonstrate the advantages of using AlFON substrates for deep UVSERRS enhancement and contribute to broadening the SERS application range with tunable and affordable substrates.

  10. Optical nanoantennas for multiband surface-enhanced infrared and raman spectroscopy

    KAUST Repository

    D'Andrea, Cristiano

    2013-04-23

    In this article we show that linear nanoantennas can be used as shared substrates for surface-enhanced Raman and infrared spectroscopy (SERS and SEIRS, respectively). This is done by engineering the plasmonic properties of the nanoantennas, so to make them resonant in both the visible (transversal resonance) and the infrared (longitudinal resonance), and by rotating the excitation field polarization to selectively take advantage of each resonance and achieve SERS and SEIRS on the same nanoantennas. As a proof of concept, we have fabricated gold nanoantennas by electron beam lithography on calcium difluoride (1-2 μm long, 60 nm wide, 60 nm high) that exhibit a transverse plasmonic resonance in the visible (640 nm) and a particularly strong longitudinal dipolar resonance in the infrared (tunable in the 1280-3100 cm -1 energy range as a function of the length). SERS and SEIRS detection of methylene blue molecules adsorbed on the nanoantenna\\'s surface is accomplished, with signal enhancement factors of 5 × 102 for SERS (electromagnetic enhancement) and up to 105 for SEIRS. Notably, we find that the field enhancement provided by the transverse resonance is sufficient to achieve SERS from single nanoantennas. Furthermore, we show that by properly tuning the nanoantenna length the signals of a multitude of vibrational modes can be enhanced with SEIRS. This simple concept of plasmonic nanosensor is highly suitable for integration on lab-on-a-chip schemes for label-free chemical and biomolecular identification with optimized performances. © 2013 American Chemical Society.

  11. Secondary ion mass spectrometric signal enhancement of phosphatidylcholine dioleoyl on enlarged nanoparticles surface

    Energy Technology Data Exchange (ETDEWEB)

    Gulin, A. [N.N. Semenov Institute of Chemical Physics, RAS, Kosigin str. 4, Moscow 119991 (Russian Federation); Mochalova, M. [Moscow Institute of Physics and Technology, Institutskii per. 9, Dolgoprudny, Moscow 141700 (Russian Federation); Denisov, N. [Institute of Problem of Chemical Physics, RAS, Semenov av. 1, Chernogolovka, 142432 (Russian Federation); Nadtochenko, V., E-mail: nadtochenko@gmail.com [N.N. Semenov Institute of Chemical Physics, RAS, Kosigin str. 4, Moscow 119991 (Russian Federation); Moscow Institute of Physics and Technology, Institutskii per. 9, Dolgoprudny, Moscow 141700 (Russian Federation); Institute of Problem of Chemical Physics, RAS, Semenov av. 1, Chernogolovka, 142432 (Russian Federation)

    2014-10-15

    Graphical abstract: - Highlights: • TOF-SIMS mass-spectra of DOPC lipid on enlarged nanoparticles surface were studied. • Metallic, semiconductor, dielectric and hybrid nanoparticles were examined. • Effect of nanoparticles on mass-spectral peaks intensity was investigated. • The highest signal enhancement of 42 times was found for hybrid core–shell Au/SiO{sub 2} nanoparticles. - Abstract: A silicon wafer surface coverage of nanoparticles (NPs) can enhance the L-α-phosphatidylcholine dioleoyl (DOPC) signal intensity in time-of-flight secondary ion mass spectrometry (TOF-SIMS). A ToF-SIMS mass spectrometer was used with a pulsed primary beam of focused 30 keV Bi{sub 3}{sup +} ions. The signal enhancing effect has been studied for metallic (Ag, Au, Pb), semiconductor (TiO{sub 2}), dielectric (SiO{sub 2}) and hybrid (Au/TiO{sub 2}NPs, core–shell Au/SiO{sub 2}) nanoparticles. Ag NPs can attenuate secondary ions signal, whereas all other studied NPs show the signal enhancement. The emission of DOPC lipid secondary ions immobilized on core–shell Au/SiO{sub 2}NPs was enhanced up to 42 times. This technique is a simple preparatory method enabling an overall increase in molecular lipid ions.

  12. Secondary ion mass spectrometric signal enhancement of phosphatidylcholine dioleoyl on enlarged nanoparticles surface

    International Nuclear Information System (INIS)

    Gulin, A.; Mochalova, M.; Denisov, N.; Nadtochenko, V.

    2014-01-01

    Graphical abstract: - Highlights: • TOF-SIMS mass-spectra of DOPC lipid on enlarged nanoparticles surface were studied. • Metallic, semiconductor, dielectric and hybrid nanoparticles were examined. • Effect of nanoparticles on mass-spectral peaks intensity was investigated. • The highest signal enhancement of 42 times was found for hybrid core–shell Au/SiO 2 nanoparticles. - Abstract: A silicon wafer surface coverage of nanoparticles (NPs) can enhance the L-α-phosphatidylcholine dioleoyl (DOPC) signal intensity in time-of-flight secondary ion mass spectrometry (TOF-SIMS). A ToF-SIMS mass spectrometer was used with a pulsed primary beam of focused 30 keV Bi 3 + ions. The signal enhancing effect has been studied for metallic (Ag, Au, Pb), semiconductor (TiO 2 ), dielectric (SiO 2 ) and hybrid (Au/TiO 2 NPs, core–shell Au/SiO 2 ) nanoparticles. Ag NPs can attenuate secondary ions signal, whereas all other studied NPs show the signal enhancement. The emission of DOPC lipid secondary ions immobilized on core–shell Au/SiO 2 NPs was enhanced up to 42 times. This technique is a simple preparatory method enabling an overall increase in molecular lipid ions

  13. Advanced Liquid Cooling for a Traction Drive Inverter Using Jet Impingement and Microfinned Enhanced Surfaces: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Waye, S. K.; Narumanchi, S.; Mihalic, M.; Moreno, G.; Bennion, K.; Jeffers, J.

    2014-08-01

    Jet impingement on plain and micro-finned enhanced surfaces was compared to a traditional channel flow configuration. The jets provide localized cooling to areas heated by the insulated-gate bipolar transistor and diode devices. Enhanced microfinned surfaces increase surface area and thermal performance. Using lighter materials and designing the fluid path to manage pressure losses increases overall performance while reducing weight, volume, and cost. Powering four diodes in the center power module of the inverter and computational fluid dynamics (CFD) modeling was used to characterize the baseline as well as jet-impingement-based heat exchangers. CFD modeling showed the thermal performance improvements should hold for a fully powered inverter. Increased thermal performance was observed for the jet-impingement configurations when tested at full inverter power (40 to 100 kW output power) on a dynamometer. The reliability of the jets and enhanced surfaces over time was also investigated. Experimentally, the junction-to- coolant thermal resistance was reduced by up to 12.5% for jet impingement on enhanced surfaces s compared to the baseline channel flow configuration. Base plate-to-coolant (convective) resistance was reduced by up to 37.0% for the jet-based configuration compared to the baseline, suggesting that while improvements to the cooling side reduce overall resistance, reducing the passive stack resistance may contribute to lowering overall junction-to-coolant resistance. Full inverter power testing showed reduced thermal resistance from the middle of the module baseplate to coolant of up to 16.5%. Between the improvement in thermal performance and pumping power, the coefficient of performance improved by up to 13% for the jet-based configuration.

  14. Applied electric field enhances DRG neurite growth: influence of stimulation media, surface coating and growth supplements

    Science.gov (United States)

    Wood, Matthew D.; Willits, Rebecca Kuntz

    2009-08-01

    Electrical therapies have been found to aid repair of nerve injuries and have been shown to increase and direct neurite outgrowth during stimulation. This enhanced neural growth existed even after the electric field (EF) or stimulation was removed, but the factors that may influence the enhanced growth, such as stimulation media or surface coating, have not been fully investigated. This study characterized neurite outgrowth and branching under various conditions: EF magnitude and application time, ECM surface coating, medium during EF application and growth supplements. A uniform, low-magnitude EF (24 or 44 V m-1) was applied to dissociated chick embryo dorsal root ganglia seeded on collagen or laminin-coated surfaces. During the growth period, cells were either exposed to NGF or N2, and during stimulation cells were exposed to either unsupplemented media (Ca2+) or PBS (no Ca2+). Parallel controls for each experiment included cells exposed to the chamber with no stimulation and cells remaining outside the chamber. After brief electrical stimulation (10 min), neurite length significantly increased 24 h after application for all conditions studied. Of particular interest, increased stimulation time (10-100 min) further enhanced neurite length on laminin but not on collagen surfaces. Neurite branching was not affected by stimulation on any surface, and no preferential growth of neurites was noted after stimulation. Overall, the results of this report suggest that short-duration electric stimulation is sufficient to enhance neurite length under a variety of conditions. While further data are needed to fully elucidate a mechanism for this increased growth, these data suggest that one focus of those investigations should be the interaction between the growth cone and the substrata.

  15. Surface Acoustic Wave (SAW-Enhanced Chemical Functionalization of Gold Films

    Directory of Open Access Journals (Sweden)

    Gina Greco

    2017-10-01

    Full Text Available Surface chemical and biochemical functionalization is a fundamental process that is widely applied in many fields to add new functions, features, or capabilities to a material’s surface. Here, we demonstrate that surface acoustic waves (SAWs can enhance the chemical functionalization of gold films. This is shown by using an integrated biochip composed by a microfluidic channel coupled to a surface plasmon resonance (SPR readout system and by monitoring the adhesion of biotin-thiol on the gold SPR areas in different conditions. In the case of SAW-induced streaming, the functionalization efficiency is improved ≈ 5 times with respect to the case without SAWs. The technology here proposed can be easily applied to a wide variety of biological systems (e.g., proteins, nucleic acids and devices (e.g., sensors, devices for cell cultures.

  16. NOx Binding and Dissociation: Enhanced Ferroelectric Surface Chemistry by Catalytic Monolayers

    Science.gov (United States)

    Kakekhani, Arvin; Ismail-Beigi, Sohrab

    2013-03-01

    NOx molecules are regulated air pollutants produced during automotive combustion. As part of an effort to design viable catalysts for NOx decomposition operating at higher temperatures that would allow for improved fuel efficiency, we examine NOx chemistry on ferroelectric perovskite surfaces. Changing the direction of ferroelectric polarization can modify surface electronic properties and may lead to switchable surface chemistry. Here, we describe our recent work on potentially enhanced surface chemistry using catalytic RuO2 monolayers on perovskite ferroelectric substrates. In addition to thermodynamic stabilization of the RuO2 layer, we present results on the polarization-dependent binding of NO, O2, N2, and atomic O and N. We present results showing that one key problem with current catalysts, involving the difficulty of releasing dissociation products (especially oxygen), can be ameliorated by this method. Primary support from Toyota Motor Engineering and Manufacturing, North America, Inc.

  17. Enhanced biomimic bactericidal surfaces by coating with positively-charged ZIF nano-dagger arrays.

    Science.gov (United States)

    Yuan, Yuan; Zhang, Yugen

    2017-10-01

    Cicada wing surfaces are covered with dense patterns of nano-pillar structure that prevent bacterial growth by rupturing adhered microbial cells. To mimic the natural nano-pillar structure, we developed a general and simple method to grow metal organic framework (MOF) nano-dagger arrays on a wide range of surfaces. These nano-daggers possess high bactericidal activity, with log reduction >7 for Escherichia coli and Staphylococcus aureus. It was hypothesized that the positively-charged ZIF-L nano-dagger surfaces enhance bacterial cell adhesion, facilitating selective and efficient bacteria killing by the rigid and sharp nano-dagger tips. This research provides a safe and clean antimicrobial surface technology which does not require external chemicals and will not cause drug resistance. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Nanostructure-Enhanced Surface Acoustic Waves Biosensor and Its Computational Modeling

    Directory of Open Access Journals (Sweden)

    Guigen Zhang

    2009-01-01

    Full Text Available Surface acoustic wave (SAW devices are considered to be very promising in providing a high-performance sensing platform with wireless and remote operational capabilities. In this review, the basic principles of SAW devices and Love-mode SAW-based biosensors are discussed first to illustrate the need for surface enhancement for the active area of a SAW sensor. Then some of the recent efforts made to incorporate nanostructures into SAW sensors are summarized. After that, a computational approach to elucidate the underlying mechanism for the operations of a Love-mode SAW biosensor with nanostructured active surface is discussed. Finally, a modeling example for a Love-mode SAW sensor with skyscraper nanopillars added to in its active surface along with some selected results is presented.

  19. Plasmon resonance tuning in metal nanostars for surface enhanced Raman scattering

    Science.gov (United States)

    Chirumamilla, Manohar; Gopalakrishnan, Anisha; Toma, Andrea; Proietti Zaccaria, Remo; Krahne, Roman

    2014-06-01

    We report the fabrication of Au nanostar arrays by means of electron beam lithography, in which the plasmon resonance energy can be tuned via the nanostar size from the visible into the near-infrared region. The spectral response of the nanostar arrays was investigated by optical extinction (transmittance) experiments, and their surface enhanced Raman scattering performance has been tested at two different excitation wavelengths, 633 nm and 830 nm, using chemisorbed Cresyl violet molecules as analyte. The experimental results are supported by numerical simulations of the spatial and spectral electric field enhancement.

  20. Plasmon resonance tuning in metal nanostars for surface enhanced Raman scattering

    International Nuclear Information System (INIS)

    Chirumamilla, Manohar; Gopalakrishnan, Anisha; Toma, Andrea; Proietti Zaccaria, Remo; Krahne, Roman

    2014-01-01

    We report the fabrication of Au nanostar arrays by means of electron beam lithography, in which the plasmon resonance energy can be tuned via the nanostar size from the visible into the near-infrared region. The spectral response of the nanostar arrays was investigated by optical extinction (transmittance) experiments, and their surface enhanced Raman scattering performance has been tested at two different excitation wavelengths, 633 nm and 830 nm, using chemisorbed Cresyl violet molecules as analyte. The experimental results are supported by numerical simulations of the spatial and spectral electric field enhancement. (papers)

  1. Nanoantennas for surface enhanced infrared spectroscopy: Effects of interaction and higher order resonant excitations

    Directory of Open Access Journals (Sweden)

    J. Aizpurua

    2011-09-01

    Full Text Available The sensitivity in surface enhanced infrared spectroscopy (SEIRS strongly depends on where the resonant excitation is spectrally located compared to the molecular vibration that is to be enhanced. In this contribution, we study the effect of coupling in the electromagnetic properties of 2D gold nanorod arrays in the IR. We also study the SEIRS activity of higher order resonant excitations in long nanoantennas to identify polaritonic signals of a supporting SiO2 layer with nanometer thickness (3 nm on a silicon substrate.

  2. Probing cytochrome c in living mitochondria with surface-enhanced Raman spectroscopy

    DEFF Research Database (Denmark)

    Brazhe, Nadezda A.; Evlyukhin, Andrey B.; Goodilin, Eugene A.

    2015-01-01

    due to the lack of non-invasive techniques. Here we suggest a novel label-free approach based on the surface-enhanced Raman spectroscopy (SERS) to monitor the redox state and conformation of cytochrome c in the electron transport chain in living mitochondria. We demonstrate that SERS spectra of living...... mitochondria placed on hierarchically structured silver-ring substrates provide exclusive information about cytochrome c behavior under modulation of inner mitochondrial membrane potential, proton gradient and the activity of ATP-synthetase. Mathematical simulation explains the observed enhancement of Raman...

  3. Gold micro- and nano-particles for surface enhanced vibrational spectroscopy of pyridostigmine bromide

    DEFF Research Database (Denmark)

    Dolgov, Leonid; Fesenko, Olena; Kavelin, Vladyslav

    2017-01-01

    Triangular gold microprisms and spherical silica nanoparticles with attached gold nano-islands were examined as an active nanostructures for the surface enhanced Raman and infrared spectroscopy. These particles were probed for the detection of pyridostigmine bromide as a safe analog of military...... compound sarin. Raman and infrared spectral bands of the pyridostigmine bromide were measured. Detailed correlation of obtained spectral bands with specific vibrations in pyridostigmine bromide was done. Silica nanoparticles with attached gold nano-islands showed more essential enhancement of the Raman...

  4. Multi-channel coherent perfect absorbers

    KAUST Repository

    Bai, Ping

    2016-05-18

    The absorption efficiency of a coherent perfect absorber usually depends on the phase coherence of the incident waves on the surfaces. Here, we present a scheme to create a multi-channel coherent perfect absorber in which the constraint of phase coherence is loosened. The scheme has a multi-layer structure such that incident waves in different channels with different angular momenta can be simultaneously and perfectly absorbed. This absorber is robust in achieving high absorption efficiency even if the incident waves become "incoherent" and possess "random" wave fronts. Our work demonstrates a unique approach to designing highly efficient metamaterial absorbers. © CopyrightEPLA, 2016.

  5. Enhancing the antibacterial performance of orthopaedic implant materials by fibre laser surface engineering

    Science.gov (United States)

    Chan, Chi-Wai; Carson, Louise; Smith, Graham C.; Morelli, Alessio; Lee, Seunghwan

    2017-05-01

    Implant failure caused by bacterial infection is extremely difficult to treat and usually requires the removal of the infected components. Despite the severe consequence of bacterial infection, research into bacterial infection of orthopaedic implants is still at an early stage compared to the effort on enhancing osseointegration, wear and corrosion resistance of implant materials. In this study, the effects of laser surface treatment on enhancing the antibacterial properties of commercially pure (CP) Ti (Grade 2), Ti6Al4V (Grade 5) and CoCrMo alloy implant materials were studied and compared for the first time. Laser surface treatment was performed by a continuous wave (CW) fibre laser with a near-infrared wavelength of 1064 nm in a nitrogen-containing environment. Staphylococcus aureus, commonly implicated in infection associated with orthopaedic implants, was used to investigate the antibacterial properties of the laser-treated surfaces. The surface roughness and topography of the laser-treated materials were analysed by a 2D roughness testing and by AFM. The surface morphologies before and after 24 h of bacterial cell culture were captured by SEM, and bacterial viability was determined using live/dead staining. Surface chemistry was analysed by XPS and surface wettability was measured using the sessile drop method. The findings of this study indicated that the laser-treated CP Ti and Ti6Al4V surfaces exhibited a noticeable reduction in bacterial adhesion and possessed a bactericidal effect. Such properties were attributable to the combined effects of reduced hydrophobicity, thicker and stable oxide films and presence of laser-induced nano-features. No similar antibacterial effect was observed in the laser-treated CoCrMo.

  6. Towards Enhanced Performance Thin-film Composite Membranes via Surface Plasma Modification.

    Science.gov (United States)

    Reis, Rackel; Dumée, Ludovic F; Tardy, Blaise L; Dagastine, Raymond; Orbell, John D; Schutz, Jürg A; Duke, Mikel C

    2016-07-01

    Advancing the design of thin-film composite membrane surfaces is one of the most promising pathways to deal with treating varying water qualities and increase their long-term stability and permeability. Although plasma technologies have been explored for surface modification of bulk micro and ultrafiltration membrane materials, the modification of thin film composite membranes is yet to be systematically investigated. Here, the performance of commercial thin-film composite desalination membranes has been significantly enhanced by rapid and facile, low pressure, argon plasma activation. Pressure driven water desalination tests showed that at low power density, flux was improved by 22% without compromising salt rejection. Various plasma durations and excitation powers have been systematically evaluated to assess the impact of plasma glow reactions on the physico-chemical properties of these materials associated with permeability. With increasing power density, plasma treatment enhanced the hydrophilicity of the surfaces, where water contact angles decreasing by 70% were strongly correlated with increased negative charge and smooth uniform surface morphology. These results highlight a versatile chemical modification technique for post-treatment of commercial membrane products that provides uniform morphology and chemically altered surface properties.

  7. Surface-enhanced Raman scattering biosensor for DNA detection on nanoparticle island substrates

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Ho, Ho Pui; Lee, Rebecca K.Y.

    2009-01-01

    We present a study on the surface-enhanced Raman scattering (SERS) properties of Ag nanoparticle island substrates (NIS) and their applications for target oligonucleotide (OND) detection. It has been found that the surface nanostructure of NIS samples can be controlled with a good degree...... on the use of the detection OND with or without the gold nanoparticle (Au-NP). Our results confirm that, when the detection OND is coupled to the Au-NP, a better sensitivity for the target OND detection, in terms of a wider dynamic range and a lower detection limit (0:4 fM versus 1nM without Au-NP), would...

  8. The controlled pulsed laser deposition of Ag nanoparticle arrays for surface enhanced Raman scattering.

    Science.gov (United States)

    D'Andrea, C; Neri, F; Ossi, P M; Santo, N; Trusso, S

    2009-06-17

    An effective method for the production of surface enhanced Raman scattering (SERS) active substrates is presented. Nanostructured silver thin films are pulsed laser deposited in an argon atmosphere. The films consist of arrays of nanoparticles whose size is controlled by the Ar pressure. The surface morphology of the films can be tuned by the laser pulse number. Nanoparticle size is calculated by a phenomenological model taking into account the dynamics of the laser generated silver plasma. The SERS activity of the films is investigated by Raman scattering of adsorbed rhodamine 6G at different concentrations.

  9. The ''Adatom Model'' of SERS (Surface Enhanced Raman Scattering): The present status

    International Nuclear Information System (INIS)

    Otto, A.; Billmann, J.; Eickmans, J.; Ertuerk, U.; Pettenkofer, C.

    1984-01-01

    The model predicts resonant Raman scattering by adsorbate vibrations through photon excited charge transfer transition from localized electronic states at sites of atomic scale roughness (e.g. 'adatoms') on silver surfaces to the affinity levels of the adsorbates. Experimental tests are discussed: search for the localized states, shifts of the affinity levels, comparison of SERS at sites of ASR and at atomically smooth parts of the surface, changes in SER vibrational bands by shifts of the affinity levels, 'SERS' vibrational selection rules. Infrared enhancement at sites of ASR is conjectured. Different hypotheses on the role of the 'porosity' of coldly deposited silver films are discussed. (orig.)

  10. Growth of Gd{sub 2}O{sub 3} coherent layers on UO{sub 2} microsphere surface via sol-gel process

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Luciana S.; Silva, Edilaine F.; Oliveira, Felipe W.F.; Pereira, Yara S.; Brandão, Alisson F.C.; Santos, Ana Maria M.; Lameiras, Fernando S.; Reis, Sergio C.; Pedrosa, Tércio A.; Santos, Armindo, E-mail: santosa@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2017-07-01

    In this work, we synthesized and characterized UO{sub 2}-Gd{sub 2}O{sub 3} nuclear fuel via three routes, aiming to solve the problems arising from the addition of Gd{sub 2}O{sub 3} in UO{sub 2} matrix. By the industrial route, the mixture of powders (UO{sub 2}, <90 μ and 6 wt% Gd{sub 2}O{sub 3} <10 μm) results in pellets with 91% TD at 1677 °C/H{sub 2}/4 h. By the mixed route, the formation of Gd{sub 2}O{sub 3} coherent layers on UO{sub 2} powder (particles <90 μ) and microsphere (225 μm) surface produced UO{sub 2} - 6 wt% Gd{sub 2}O{sub 3} pellets with 95% (powder; 1625 °C/H{sub 2}/4 hr) and 83% (microsphere; 1677°C/H{sub 2}/4 hr) TD. By the sol-gel route, we obtained UO{sub 2} - 6 wt% Gd{sub 2}O{sub 3} in a deagglomerated (powder; <70 μm) or agglomerated microsphere 232 μm) form whose pellets reached > 97% (powder) and >98% (microsphere) TI) at 1677 °C/H{sub 2}/4h. According to XRD, OM, and SEM/EDS analysis, the referred three routes do not form a complete solid solution of UO{sub 2}-Gd{sub 2}O{sub 3} at the temperatures and time of sintering used; Gd{sub 2}O{sub 3} granule islands are present in the pellets originating from these routes. The obtained results suggest that the topological arrangement and the deficient nanostructuring of UO{sub 2} and Gd{sub 2}O{sub 3} phases, either in the raw material (powder and microsphere) as in their compacts, are the cause of low densification and irregular distribution of Gd{sub 2}O{sub 3} in UO{sub 2} matrix; mixing of U and Gd at the molecular level does not form a solid solution; and the mixed route is a good alternative to the industrial route. (author)

  11. Enhanced protein retention on poly(caprolactone) via surface initiated polymerization of acrylamide

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Yuhao; Cai, Mengtan; He, Liu [College of Polymer Science and Engineering, Sichuan University, Chengdu 610065 (China); Luo, Xianglin, E-mail: luoxl@scu.edu.cn [College of Polymer Science and Engineering, Sichuan University, Chengdu 610065 (China); State Key Laboratory of Polymer Material and Engineering, Sichuan University, Chengdu 610065 (China)

    2016-01-01

    Graphical abstract: - Highlights: • Dense package of poly(acrylamide) on poly(caprolactone) surface was achieved by surface-initiated atom transfer radical polymerization. • Poly(acrylamide) grafted surface exhibited high protein retention ability. • Loaded protein was resistant to detachment and maintained its structure without denaturation. - Abstract: To enhance the biocompatibility or extend the biomedical application of poly(caprolactone) (PCL), protein retention on PCL surface is often required. In this study, poly(acrylamide) (PAAm) brushes were grown from PCL surface via surface-initiated atom transfer radical polymerization (SI-ATRP) and served as a protein-capturing platform. Grafted PAAm was densely packed on surface and exhibited superior protein retention ability. Captured protein was found to be resistant to washing under detergent environment. Furthermore, protein structure after being captured was investigated by circular dichroism (CD) spectroscopy, and the CD spectra verified that secondary structure of captured proteins was maintained, indicating no denaturation of protein happened for retention process.

  12. Enhancing structural integrity of adhesive bonds through pulsed laser surface micro-machining

    KAUST Repository

    Diaz, Edwin Hernandez

    2015-06-01

    Enhancing the effective peel resistance of plastically deforming adhesive joints through laser-based surface micro-machining Edwin Hernandez Diaz Inspired by adhesion examples commonly found in nature, we reached out to examine the effect of different kinds of heterogeneous surface properties that may replicate this behavior and the mechanisms at work. In order to do this, we used pulsed laser ablation on copper substrates (CuZn40) aiming to increase adhesion for bonding. A Yb-fiber laser was used for surface preparation of the substrates, which were probed with a Scanning Electron Microscope (SEM) and X-ray Photoelectron Spectroscopy (XPS). Heterogeneous surface properties were devised through the use of simplified laser micromachined patterns which may induce sequential events of crack arrest propagation, thereby having a leveraging effect on dissipation. The me- chanical performance of copper/epoxy joints with homogeneous and heterogeneous laser micromachined interfaces was then analyzed using the T-peel test. Fractured surfaces were analyzed using SEM to resolve the mechanism of failure and adhesive penetration within induced surface asperities from the treatment. Results confirm positive modifications of the surface morphology and chemistry from laser ablation that enable mechanical interlocking and cohesive failure within the adhesive layer. Remarkable improvements of apparent peel energy, bond toughness, and effective peel force were appreciated with respect to sanded substrates as control samples.

  13. A Novel RFID Sensing System Using Enhanced Surface Wave Technology for Battery Exchange Stations

    Directory of Open Access Journals (Sweden)

    Yeong-Lin Lai

    2014-01-01

    Full Text Available This paper presents a novel radio-frequency identification (RFID sensing system using enhanced surface wave technology for battery exchange stations (BESs of electric motorcycles. Ultrahigh-frequency (UHF RFID technology is utilized to automatically track and manage battery and user information without manual operation. The system includes readers, enhanced surface wave leaky cable antennas (ESWLCAs, coupling cable lines (CCLs, and small radiation patches (SRPs. The RFID sensing system overcomes the electromagnetic interference in the metallic environment of a BES cabinet. The developed RFID sensing system can effectively increase the efficiency of BES operation and promote the development of electric vehicles which solve the problem of air pollution as well as protect the environment of the Earth.

  14. Polytetrafluorethylene-Au as a substrate for surface-enhanced Raman spectroscopy

    Directory of Open Access Journals (Sweden)

    Siegel Jakub

    2011-01-01

    Full Text Available Abstract This study deals with preparation of substrates suitable for surface-enhanced Raman spectroscopy (SERS applications by sputtering deposition of gold layer on the polytetrafluorethylene (PTFE foil. Time of sputtering was investigated with respect to the surface properties. The ability of PTFE-Au substrates to enhance Raman signals was investigated by immobilization of biphenyl-4,4'-dithiol (BFD from the solutions with various concentrations. BFD was also used for preparation of sandwich structures with Au or Ag nanoparticles by two different procedures. Results showed that PTFE can be used for fabrication of SERS active substrate with easy handle properties at low cost. This substrate was sufficient for the measurement of SERS spectrum of BFD even at 10-8 mol/l concentration.

  15. Highly reproducible surface-enhanced Raman spectra on semiconductor SnO2 octahedral nanoparticles.

    Science.gov (United States)

    Jiang, Li; Yin, Penggang; You, Tingting; Wang, Hua; Lang, Xiufeng; Guo, Lin; Yang, Shihe

    2012-12-07

    Highly reproducible surface-enhanced Raman scattering (SERS) spectra are obtained on the surface of SnO(2) octahedral nanoparticles. The spot-to-spot SERS signals show a relative standard deviation (RSD) consistently below 20 % in the intensity of the main Raman peaks of 4-mercaptobenzoic acid (4-MBA) and 4-nitrobenzenethiol (4-NBT), indicating good spatial uniformity and reproducibility. The SERS signals are believed to mainly originate from a charge-transfer (CT) mechanism. Time-dependent density functional theory (TD-DFT) is used to simulate the SERS spectrum and interpret the chemical enhancement mechanism in the experiment. The research extends the application of SERS and also establishes a new uniform SERS substrate. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. The osmolyte xylitol reduces the salt concentration of airway surface liquid and may enhance bacterial killing

    Science.gov (United States)

    Zabner, Joseph; Seiler, Michael P.; Launspach, Janice L.; Karp, Philip H.; Kearney, William R.; Look, Dwight C.; Smith, Jeffrey J.; Welsh, Michael J.

    2000-10-01

    The thin layer of airway surface liquid (ASL) contains antimicrobial substances that kill the small numbers of bacteria that are constantly being deposited in the lungs. An increase in ASL salt concentration inhibits the activity of airway antimicrobial factors and may partially explain the pathogenesis of cystic fibrosis (CF). We tested the hypothesis that an osmolyte with a low transepithelial permeability may lower the ASL salt concentration, thereby enhancing innate immunity. We found that the five-carbon sugar xylitol has a low transepithelial permeability, is poorly metabolized by several bacteria, and can lower the ASL salt concentration in both CF and non-CF airway epithelia in vitro. Furthermore, in a double-blind, randomized, crossover study, xylitol sprayed for 4 days into each nostril of normal volunteers significantly decreased the number of nasal coagulase-negative Staphylococcus compared with saline control. Xylitol may be of value in decreasing ASL salt concentration and enhancing the innate antimicrobial defense at the airway surface.

  17. Development of batch producible hot embossing 3D nanostructured surface-enhanced Raman scattering chip technology

    Science.gov (United States)

    Huang, Chu-Yu; Tsai, Ming-Shiuan

    2017-09-01

    The main purpose of this study is to develop a batch producible hot embossing 3D nanostructured surface-enhanced Raman chip technology for high sensitivity label-free plasticizer detection. This study utilizing the AAO self-assembled uniform nano-hemispherical array barrier layer as a template to create a durable nanostructured nickel mold. With the hot embossing technique and the durable nanostructured nickel mold, we are able to batch produce the 3D Nanostructured Surface-enhanced Raman Scattering Chip with consistent quality. In addition, because of our SERS chip can be fabricated by batch processing, the fabrication cost is low. Therefore, the developed method is very promising to be widespread and extensively used in rapid chemical and biomolecular detection applications.

  18. Surface-enhanced infrared absorption (SEIRA) of adsorbates on copper nanoparticles synthesized by galvanic displacement.

    Science.gov (United States)

    Fasasi, Ayuba; Griffiths, Peter R; Scudiero, Louis

    2011-07-01

    Copper nanoparticles (Cu NPs) were made by electroless deposition on Ge disks as substrates for surface-enhanced infrared absorption (SEIRA). Previous X-ray photoelectron spectra had shown that elemental copper is deposited on the Ge substrate and that the nanoparticulate film remains resistant to oxidation even after several days of air exposure at room temperature. SEIRA spectra of p-nitrothiophenol (p-NTP) adsorbed on the copper nanoparticles were measured. Freshly made substrates made by electroless deposition gave higher enhancements than both the 12-day-old oxidized substrates and substrates made by physical vapor deposition. The intensity of the antisymmetric NO(2) stretching band of p-NTP relative to that of the symmetric stretch was significantly higher for p-NTP adsorbed on copper than on silver nanofilms, indicating that the C(2) axis of the aromatic ring is tilted with respect to the copper surface.

  19. Frontiers of surface-enhanced Raman scattering single nanoparticles and single cells

    CERN Document Server

    Ozaki, Yukihiro; Aroca, Ricardo

    2014-01-01

    A comprehensive presentation of Surface-Enhanced Raman Scattering (SERS) theory, substrate fabrication, applications of SERS to biosystems, chemical analysis, sensing and fundamental innovation through experimentation. Written by internationally recognized editors and contributors. Relevant to all those within the scientific community dealing with Raman Spectroscopy, i.e. physicists, chemists, biologists, material scientists, physicians and biomedical scientists. SERS applications are widely expanding and the technology is now used in the field of nanotechnologies, applications to biosystems, nonosensors, nanoimaging and nanoscience.

  20. Mathematical model for biomolecular quantification using large-area surface-enhanced Raman spectroscopy mapping

    DEFF Research Database (Denmark)

    Palla, Mirkó; Bosco, Filippo; Yang, Jaeyoung

    2015-01-01

    Surface-enhanced Raman spectroscopy (SERS) based on nanostructured platforms is a promising technique for quantitative and highly sensitive detection of biomolecules in the field of analytical biochemistry. Here, we report a mathematical model to predict experimental SERS signal (or hotspot......) intensity distributions of target molecules on receptor-functionalized nanopillar substrates for biomolecular quantification. We demonstrate that by utilizing only a small set of empirically determined parameters, our general theoretical framework agrees with the experimental data particularly well...

  1. High-Surface-Area Porous Platinum Electrodes for Enhanced Charge Transfer

    OpenAIRE

    Hu Yelin; Yella Aswani; Guldin Stefan; Schreier Marcel; Stellacci Francesco; Grätzel Michael; Stefik Morgan

    2014-01-01

    Cobalt based electrolytes are highly tunable and have pushed the limits of dye sensitized solar cells enabling higher open circuit voltages and new record effi ciencies. However the performance of these electrolytes and a range of other electrolytes suffer from slow electron transfer at platinum counter electrodes. High surface area platinum would enhance catalysis but pure platinum structures are too expensive in practice. Here a material effi cient host guest architecture is developed that ...

  2. Biomimicry using Nano-Engineered Enhanced Condensing Surfaces for Sustainable Fresh Water Technology

    OpenAIRE

    Al-Beaini, Sara

    2012-01-01

    Biomimicry offers innovative sustainable solutions for many dire resource-based challenges. The Namib Desert beetle (sp. Stenocara) invites us to explore how we can collect fresh water more energy-efficiently. The beetle's unique back features with alternating hydrophobic-hydrophilic regions, aid its survival in a water scarce desert environment. We investigated the feasibility for enhanced condensation by patterning a zinc oxide (ZnO) surface to mimic the beetle's back. ZnO was selected as t...

  3. SU-F-T-93: Breast Surface Dose Enhancement Using a Clinical Prone Breast Board

    Energy Technology Data Exchange (ETDEWEB)

    Guerra, M; Jozsef, G [New York University Langone Medical Center, New York, NY (United States)

    2016-06-15

    Purpose: The use of specialized patient set-up devices in radiotherapy, such as prone breast boards, may have unwanted dosimetric effects. The goal of this study was to evaluate the effect of a clinically used prone breast board on skin dose due to buildup. Methods: GafChromic film (EBT3) was used for dose measurements on the surface of a solid water phantom shaped to mimic the curvature of the breast. We investigated two setup scenarios: the medial field border placed at the medial edge of the board and 1 cm contralaterally from that edge. A strip of film was taped to the medial surface of the phantom. Gantry angles varied from 10 to 30 degrees below the lateral gantry position, representing anterior oblique fields. The measurements were performed with and without the presence of the board; the ratio of their corresponding doses (dose enhancement) was evaluated. Results: For the cases where the field edge is at the edge of the board, the dose enhancement is negligible for all the tested angles. When the field edge is 1 cm inside the board, the maximum surface dose enhancement varies depending on the gantry angle between 2.2 for 30 degrees and 3.2 for 20 degrees. The length on the film at which the presence of the board is detectable (i.e. where there is dose enhancement) is longer for the shallower angles. Conclusion: Even the low-density, thin carbon fiber board with a thin soft foam pad on the top can produce significant dose enhancement on the skin in prone breast treatment due to loss of buildup. However, it happens only when the patient mid-sternum is over the board, i.e. the medial edge of the field traverses through the board and pad. Even then, the effect occurs only at the field edge, i.e. the penumbral region.

  4. Focal Molography: Coherent Microscopic Detection of Biomolecular Interaction

    Directory of Open Access Journals (Sweden)

    Christof Fattinger

    2014-08-01

    Full Text Available We introduce and theoretically investigate here a novel analytical method that we have called focal molography, in which molecular interactions are made visible through scattering of coherent light by a coherent pattern of molecules. The scattered light quantifies the presence of molecules at molecular interaction sites. It is separated from noncoherent background scatter by a combination of local dark-field illumination, interference enhancement, and spatial filtering. The latter is achieved by holographic focusing of the wave field generated by the coherently assembled molecules onto an Airy disk and by subtraction of the noncoherent irradiance in the focal plane outside the disk from the irradiance in the disk. This new microscopic method allows distinct detection of low-refractive-index contrast in the nanoenvironment of biomolecules from which information on the interaction of the coherently assembled molecules with molecules in a liquid or gaseous sample may be deduced. The noncoherent surroundings of the coherently assembled molecules consist of freely diffusing solvent and solute molecules. The surroundings, as well as changes in temperature, do not contribute to the coherent signal in the diffraction focus. Interference lithography or high-resolution-imaging lithography can be used to synthesize the coherent pattern of molecules on a monolithic substrate. The coherent pattern of molecules constitutes a synthetic phase hologram that creates a diffraction-limited light wave. We suggest the term “mologram” for the coherent assembly of functional nanostructures and the term “focal molography” for label-free or labeled analysis of molecular interactions through the measurement of the properties of light in the focus of the mologram. We derive analytical formulas that express the detection signal and the sensitivity of focal molography on the surface of a high-refractive-index thin-film optical waveguide in terms of known parameters

  5. Detection of melamine on fractals of unmodified gold nanoparticles by surface-enhanced Raman scattering.

    Science.gov (United States)

    Roy, Pradip Kumar; Huang, Yi-Fan; Chattopadhyay, Surojit

    2014-01-01

    A simple way of detecting melamine in raw milk is demonstrated via surface-enhanced Raman spectroscopy (SERS) using fractals of bare and nonfunctionalized ~30 nm gold nanoparticles (AuNP) distributed on a solid support. The technique demonstrates the formation of AuNP fractals, from a random distribution, upon exposure to melamine, that enhance the Raman scattering cross-section to enable detection by SERS. The agglomeration, which is pronounced at higher melamine concentrations, is demonstrated directly through imaging, and the red-shift of the plasmon absorption peak of the AuNP fractal away from 530 nm by finite difference time domain (FDTD) calculations. The agglomeration results in a strong plasmon field, shown by FDTD, over the interparticle sites that enhances the Raman scattering cross-section of melamine and ensures unambiguous detection. Limit of detection of 100 ppb could be achieved reproducibly.

  6. Wind enhances differential air advection in surface snow at sub-meter scales

    Science.gov (United States)

    Drake, Stephen A.; Selker, John S.; Higgins, Chad W.

    2017-09-01

    Atmospheric pressure gradients and pressure fluctuations drive within-snow air movement that enhances gas mobility through interstitial pore space. The magnitude of this enhancement in relation to snow microstructure properties cannot be well predicted with current methods. In a set of field experiments, we injected a dilute mixture of 1 % carbon monoxide (CO) and nitrogen gas (N2) of known volume into the topmost layer of a snowpack and, using a distributed array of thin film sensors, measured plume evolution as a function of wind forcing. We found enhanced dispersion in the streamwise direction and also along low-resistance pathways in the presence of wind. These results suggest that atmospheric constituents contained in snow can be anisotropically mixed depending on the wind environment and snow structure, having implications for surface snow reaction rates and interpretation of firn and ice cores.

  7. Perfect-absorption graphene metamaterials for surface-enhanced molecular fingerprint spectroscopy

    Science.gov (United States)

    Guo, Xiangdong; Hu, Hai; Liao, Baoxin; Zhu, Xing; Yang, Xiaoxia; Dai, Qing

    2018-05-01

    Graphene plasmon with extremely strong light confinement and tunable resonance frequency represents a promising surface-enhanced infrared absorption (SEIRA) sensing platform. However, plasmonic absorption is relatively weak (approximately 1%-9%) in monolayer graphene nanostructures, which would limit its sensitivity. Here, we theoretically propose a hybrid plasmon-metamaterial structure that can realize perfect absorption in graphene with a low carrier mobility of 1000 cm2 V-1 s-1. This structure combines a gold reflector and a gold grating to the graphene plasmon structures, which introduce interference effect and the lightning-rod effect, respectively, and largely enhance the coupling of light to graphene. The vibration signal of trace molecules can be enhanced up to 2000-fold at the hotspot of the perfect-absorption structure, enabling the SEIRA sensing to reach the molecular level. This hybrid metal-graphene structure provides a novel path to generate high sensitivity in nanoscale molecular recognition for numerous applications.

  8. Improved surface-enhanced Raman scattering on arrays of gold quasi-3D nanoholes

    KAUST Repository

    Yue, Weisheng

    2012-10-04

    Arrays of gold quasi-3D nanoholes were proposed and fabricated as substrates for surface-enhanced Raman scattering (SERS). By detecting rhodamine 6G (R6G) molecules, the gold quasi-3D nanoholes demonstrated an SERS intensity that was 25-62 times higher than that of two-dimensional nanoholes with the same geometrical shapes and periodicities. The larger SERS enhancement of the quasi-3D nanoholes is attributed to the enhanced electromagnetic field on the top-layer nanohole, the bottom nanodiscs and the field coupling between the two layers. In addition, the investigation of the shape dependence of the SERS on the quasi-3D nanoholes demonstrated that the quadratic, circular, triangular and rhombic holes exhibited different SERS properties. Numerical simulations of the electromagnetic properties on the nanostructures were performed with CST Microwave Studio, and the results agree with the experimental observations. © 2012 IOP Publishing Ltd.

  9. Surface enhanced imaging and IR spectroscopy of the biological cells on the nanostructured gold film

    Directory of Open Access Journals (Sweden)

    G.I. Dovbeshko

    2017-07-01

    Full Text Available New approach for optical imaging, structural study and cell cultivation based on the effect of the enhancement of optical signals from biomolecules and biological cells near nanostructured rough gold surface is proposed. The surface enhanced IR absorption (SEIRA spectroscopy and confocal microscopy experiments were made using the culture of SPEV (porcine embryonic kidney epithelium transplantable line and fibroblast cells, cultivated and/or adsorbed on the gold substrate. The SEIRA spectra registered from monolayer of the SPEV cells cultivated on the rough gold showed a low frequency shift of about 2 to 7 cm 1 for the most characteristic IR vibrations, compared with those adsorbed from suspension on the same substrate. An enhancement factor of 15…30 was obtained for different molecular vibrations. The confocal microscopy contrast images of the SPEV cells on rough gold substrate were obtained in laser fluorescence mode. This approach opens new possibilities for visualization of the living cells in vivo without staining. The fluorescence of the rough gold surfaces and effects responsible for our findings have been discussed.

  10. [The investigation of humic acid by surface-enhanced Raman spectroscopy].

    Science.gov (United States)

    Zhang, Wen-Juan; Li, Ying; Guo, Jin-Jia; Xiao, Qiong; Yu, Li

    2013-05-01

    Humic acid (HA), which are organic compounds widely existing in the oceans, rivers and soil, has important significance for the environmental monitoring of soil and water. In this paper, ai ming at the problem of Surface-enhanced Raman Spectroscopy (SERS) applying for HA detection in water, the characteristics of the humic acid on silver colloids was studied by means of SERS. The influence of laser irradiation time, HA concentrations and pH value on the surface-enhanced effects of HA were investigated. The experimental results show that the SERS spectra of HA is ideal when the laser irradiation time between 20-30 min. The SERS of different HA concentrations was detected. It was found that the relative intensity at 1 379 cm(-1) increased as a linear function of the concentration of HA with correlation coefficient R2 of 0.993. The SERS of HA was found to be very sensitive to pH, the SERS spectra of HA was very weak at neutral pH, but at acidic pH and alkaline pH a remarkable increase of SERS intensity occurred. The SERS of HA in running water was detected too. The experimental results show that it is feasible to detect HA in natural water by means of surface-enhanced Raman spectroscopy.

  11. Surface-Enhanced Raman Spectroscopy forStaphylococcus aureusDNA Detection by Using Surface-Enhanced Raman Scattering Tag on Au Film Over Nanosphere Substrate.

    Science.gov (United States)

    Chen, Jian; Wang, Jun-Feng; Wu, Xue-Zhong; Rong, Zhen; Dong, Pei-Tao; Xiao, Rui

    2018-06-01

    We developed a high-performance surface-enhanced Raman scattering (SERS) sensing platform that can be used for specific and sensitive DNA detection. The SERS platform combines the advantages of Au film over nanosphere (AuFON) substrate and Ag@PATP@SiO2 SERS tag. SERS tag-on-AuFON is a sensing system that operates by the self-assembly of SERS tag onto an AuFON substrate in the presence of target DNAs. The SERS signals can be dramatically enhanced by the formation of "hot spots" in the interstices between the assembled nanostructures, as confirmed by finite-difference time-domain (FDTD) simulation. As a new sensing platform, SERS tag-on-AuFON was utilized to detect Staphylococcus aureus (S. aureus) DNA with a limit of detection at 1 nM. A linear relationship was also observed between the SERS intensity at Raman peak 1439 cm-1 and the logarithm of target DNA concentrations ranging from 1 μM to 1 nM. Besides, the sensing platform showed good homogeneity, with a relative standard deviation of about 1%. The sensitive SERS platform created in this study is a promising tool for detecting trace biochemical molecules because of its relatively simple and effective fabrication procedure, high sensitivity, and high reproducibility of the SERS effect.

  12. Gold-enhanced biomolecular surface imaging of cells and tissue by SIMS and MALDI mass spectrometry.

    Science.gov (United States)

    Altelaar, A F Maarten; Klinkert, Ivo; Jalink, Kees; de Lange, Robert P J; Adan, Roger A H; Heeren, Ron M A; Piersma, Sander R

    2006-02-01

    Surface metallization by plasma coating enhances desorption/ionization of membrane components such as lipids and sterols in imaging time-of-flight secondary ion mass spectrometry (TOF-SIMS) of tissues and cells. High-resolution images of cholesterol and other membrane components were obtained for neuroblastoma cells and revealed subcellular details (resolving power 1.5 mum). Alternatively, in matrix-enhanced SIMS, 2,5-dihydroxybenzoic acid electrosprayed on neuroblastoma cells allowed intact molecular ion imaging of phosphatidylcholine and sphingomyelin at the cellular level. Gold deposition on top of matrix-coated rat brain tissue sections strongly enhanced image quality and signal intensity in stigmatic matrix-assisted laser desorption/ionization imaging mass spectrometry. High-quality total ion count images were acquired, and the neuropeptide vasopressin was localized in the rat brain tissue section at the hypothalamic area around the third ventricle. Although the mechanism of signal enhancement by gold deposition is under debate, the results we have obtained for cells and tissue sections illustrate the potential of this sample preparation technique for biomolecular surface imaging by mass spectrometry.

  13. Gold split-ring resonators (SRRs) as substrates for surface-enhanced raman scattering

    KAUST Repository

    Yue, Weisheng

    2013-10-24

    We used gold split ring resonators (SRRs) as substrates for surface-enhanced Raman scattering (SERS). The arrays of SRRs were fabricated by electron-beam lithography in combination with plasma etching. In the detection of rhodamine 6G (R6G) molecules, SERS enhancement factors of the order of 105 was achieved. This SERS enhancement increased as the size of the split gap decrease as a consequence of the matching between the resonance wavelength of the SRRs and the excitation wavelength of SERS. As the size of the split gap decreased, the localized surface plasmon resonance shifted to near the excitation wavelength and, thus, resulted in the increase in the electric field on the nanostructures. We used finite integration method (FIT) to simulate numerically the electromagnetic properties of the SRRs. The results of the simulation agreed well with our experimental observations. We anticipate this work will provide an approach to manipulate the SERS enhancement by modulating the size of split gap with SRRs without affecting the area and structural arrangement. © 2013 American Chemical Society.

  14. Surface enhanced Raman scattering for detection of Pseudomonas aeruginosa quorum sensing compounds

    Science.gov (United States)

    Thrift, Will; Bhattacharjee, Arunima; Darvishzadeh-Varcheie, Mahsa; Lu, Ying; Hochbaum, Allon; Capolino, Filippo; Whiteson, Katrine; Ragan, Regina

    2015-08-01

    Pseudomonas aeruginosa (PA), a biofilm forming bacterium, commonly affects cystic fibrosis, burn victims, and immunocompromised patients. PA produces pyocyanin, an aromatic, redox active, secondary metabolite as part of its quorum sensing signaling system activated during biofilm formation. Surface enhanced Raman scattering (SERS) sensors composed of Au nanospheres chemically assembled into clusters on diblock copolymer templates were fabricated and the ability to detect pyocyanin to monitor biofilm formation was investigated. Electromagnetic full wave simulations of clusters observed in scanning electron microcopy images show that the localized surface plasmon resonance wavelength is 696 nm for a dimer with a gap spacing of 1 nm in an average dielectric environment of the polymer and analyte; the local electric field enhancement is on the order of 400 at resonance, relative to free space. SERS data acquired at 785 nm excitation from a monolayer of benzenethiol on fabricated samples was compared with Raman data of pure benzenethiol and enhancement factors as large as 8×109 were calculated that are consistent with simulated field enhancements. Using this system, the limit of detection of pyocyanin in pure gradients was determined to be 10 parts per billion. In SERS data of the supernatant from the time dependent growth of PA shaking cultures, pyocyanin vibrational modes were clearly observable during the logarithmic growth phase corresponding to activation of genes related to biofilm formation. These results pave the way for the use of SERS sensors for the early detection of biofilm formation, leading to reduced healthcare costs and better patient outcomes.

  15. Surface-enhanced Raman scattering active gold nanoparticle/nanohole arrays fabricated through electron beam lithography

    Science.gov (United States)

    Wu, Tsunghsueh; Lin, Yang-Wei

    2018-03-01

    Effective surface-enhanced Raman scattering (SERS)-active substrates from gold nanoparticle and gold nanohole arrays were successfully fabricated through electron beam lithography with precise computer-aided control of the unit size and intergap distance. Their SERS performance was evaluated using 4-mercaptobenzoic acid (4-MBA). These gold arrays yielded strong SERS signals under 785 nm laser excitation. The enhancement factors for 4-MBA molecules on the prepared gold nanoparticle and nanohole arrays maxed at 1.08 × 107 and 8.61 × 106, respectively. The observed increase in SERS enhancement was attributed to the localized surface plasmon resonance (LSPR) wavelength shifting toward the near-infrared regime when the gold nanohole diameter increased, in agreement with the theoretical prediction in this study. The contribution of LSPR to the Raman enhancement from nanohole arrays deposited on fluorine-doped tin oxide glass was elucidated by comparing SERS and transmission spectra. This simple fabrication procedure, which entails employing electron beam lithography and the controllability of the intergap distance, suggests highly promising uses of nanohole arrays as functional components in sensing and photonic devices.

  16. Surface-enhanced Raman spectroscopy on laser-engineered ruthenium dye-functionalized nanoporous gold

    Energy Technology Data Exchange (ETDEWEB)

    Schade, Lina [Department of Chemistry, Universität Duisburg-Essen, 45117 Essen (Germany); Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 47057 Duisburg (Germany); Franzka, Steffen [Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 47057 Duisburg (Germany); Interdisciplinary Center for Analytics on the Nanoscale (ICAN), University of Duisburg-Essen, 47047 Duisburg (Germany); Biener, Monika; Biener, Jürgen [Nanoscale Synthesis and Characterization Laboratory, Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, CA 94550 (United States); Hartmann, Nils, E-mail: nils.hartmann@uni-due.de [Department of Chemistry, Universität Duisburg-Essen, 45117 Essen (Germany); Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 47057 Duisburg (Germany); Interdisciplinary Center for Analytics on the Nanoscale (ICAN), University of Duisburg-Essen, 47047 Duisburg (Germany)

    2016-06-30

    Graphical abstract: - Highlights: • Photothermal laser processing is used to modify the surface structure of nanoporous gold. • Laser-fabricated structures exhibit pore sizes in the range from 25 nm to 200 nm and higher. • Ru-dye-functionalized surface structures are used in surface-enhanced Raman spectroscopy (SERS) studies. • Raman peak intensities of N719, a commercial Ru-dye, exhibit a strong dependence on the pore size. • Maximum Raman peak intensities are observed for small pore sizes close to 25 nm. - Abstract: Photothermal processing of nanoporous gold with a microfocused continuous-wave laser at λ = 532 nm provides a facile means in order engineer the pore and ligament size of nanoporous gold. In this report we take advantage of this approach in order to investigate the size-dependence of enhancement effects in surface-enhanced Raman spectroscopy (SERS). Surface structures with laterally varying pore sizes from 25 nm to ≥200 nm are characterized using scanning electron microscopy and then functionalized with N719, a commercial ruthenium complex, which is widely used in dye-sensitized solar cells. Raman spectroscopy reveals the characteristic spectral features of N719. Peak intensities strongly depend on the pore size. Highest intensities are observed on the native support, i.e. on nanoporous gold with pore sizes around 25 nm. These results demonstrate the particular perspectives of laser-fabricated nanoporous gold structures in fundamental SERS studies. In particular, it is emphasized that laser-engineered porous gold substrates represent a very well defined platform in order to study size-dependent effects with high reproducibility and precision and resolve conflicting results in previous studies.

  17. Electrical pulse – mediated enhanced delivery of silver nanoparticles into living suspension cells for surface enhanced Raman spectroscopy

    International Nuclear Information System (INIS)

    Lin, J; Li, B; Feng, S; Chen, G; Li, Y; Huang, Z; Chen, R; Yu, Y; Huang, H; Lin, S; Li, C; Su, Y; Zeng, H

    2012-01-01

    Electrical pulse-mediated enhanced silver nanoparticles delivery is a much better method for intracellular surface-enhanced Raman spectroscopy (SERS) measurements of suspension cells. Robust and high-quality SERS spectra of living suspension cells were obtained based on an electroporation-SERS method, which can overcomes the shortcoming of non-uniform distribution of silver nanoparticles localized in the cell cytoplasm after electroporation and reduces the amount variance of silver nanoparticles delivered into different cells. The electroporation parameters include three 150 V (375 V/cm) electric pulses of 1, 5, and 5 ms durations respectively. Our results indicate that considerable amount of silver nanoparticles can be rapidly delivered into the human promyelocytic leukemia HL60 cells, and the satisfied SERS spectra were obtained while the viability of the treated cells was highly maintained (91.7%). The electroporation-SERS method offers great potential approach in delivering silver nanoparticles into living suspension cells, which is useful for widely biomedical applications including the real-time intracellular SERS analysis of living cells

  18. Enhancing the stability of xylanase from Cellulomonas fimi by cell-surface display on Escherichia coli.

    Science.gov (United States)

    Chen, Y-P; Hwang, I-E; Lin, C-J; Wang, H-J; Tseng, C-P

    2012-03-01

    The cell-surface display of Cex, which encodes xylanase and exoglucanase from Cellulomonas fimi, was constructed on Escherichia coli using PgsA as the anchor protein. Characterization of the cell-surface display of Cex was performed. PgsA was fused to the N-terminus of Cex and six histidines were utilized as spacers between the targeting and anchor proteins. Successful cell-surface display of Cex was demonstrated by Western blot and immunofluorescence analyses on E. coli C41 (DE3). According to the time-course analysis, the xylanase activity of Cex was achieved at 49Ug(-1) dry cell weight after 12 h culture at 37°C. The optimal temperature and pH ranges of the cell-surface displayed protein with whole-cell were broader than the corresponding ranges of the purified form. Further determination of thermostability indicated that the half-life of cell-surface displayed Cex was 1·6 times longer than that of purified Cex at 60°C. We have successfully developed the cell-surface display of xylanase on E. coli. The cell-surface display can enhance the stability of xylanase against changes in temperature and has the potential of becoming a whole-cell biocatalyst for industrial applications, such as biobleaching of paper and production of renewable energy. The results demonstrated that the cell-surface display of xylanase embedded in the cell membrane is more stable than that of the purified enzyme. Thus, to improve the stability of heterologous proteins production, cell-surface display using the PgsA anchor protein as a tool can be considered in E. coli. © 2012 The Authors. Journal of Applied Microbiology © 2012 The Society for Applied Microbiology.

  19. Decreased fibrous encapsulation and enhanced osseointegration in vitro by decorin-modified titanium surface.

    Science.gov (United States)

    He, Ronghan; Lu, Yunxiang; Ren, Jianhua; Wang, Zhe; Huang, Junqi; Zhu, Lei; Wang, Kun

    2017-07-01

    Orthopedic implants, using materials such as titanium, are extensively used in clinical surgeries. Despite its popularity, titanium is still inadequate to reliable osseointegration due to aseptic loosing. Fibrous encapsulation on the titanium implant interface prevents osseointegration and leads to the loosing of orthopedic implant. In this study, decorin was loaded on titanium surface by polydopamine film to examine fibrous encapsulation inhibition and bone growth acceleration. The coating of decorin was evaluated by X-ray photoelectron spectroscopy (XPS) and fluorescence microscopy. Quantitative analysis showed increased decorin coating on titanium surface when decorin in the loading solution increases. To test the effect of decorin modification, fibroblast and osteoblast cultures were utilized in vitro. The results showed that the functions of fibroblasts (proliferation, migration and collagen synthesis) were significantly attenuated on the decorin-modified surfaces and this anti-fibrous effect could be due to fibrotic gene suppression by decorin. In contrast, osteoblastic activities, such as calcium deposition and alkaline phosphatase (ALP) activity, were enhanced by the modified decorin. These results suggest that decorin coating on titanium surface inhibited proliferation and function of fibroblasts and improved that of osteoblasts. Therefore, this study is potentially useful for enhancing orthopedic implant. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Seasonal Change in Wetland Coherence as an Aid to Wetland Monitoring

    Directory of Open Access Journals (Sweden)

    Brian Brisco

    2017-02-01

    Full Text Available Water is an essential natural resource, and information about surface water conditions can support a wide variety of applications, including urban planning, agronomy, hydrology, electrical power generation, disaster relief, ecology and preservation of natural areas. Synthetic Aperture Radar (SAR is recognized as an important source of data for monitoring surface water, especially under inclement weather conditions, and is used operationally for flood mapping applications. The canopy penetration capability of the microwaves also allows for mapping of flooded vegetation as a result of enhanced backscatter from what is generally believed to be a double-bounce scattering mechanism between the water and emergent vegetation. Recent investigations have shown that, under certain conditions, the SAR response signal from flooded vegetation may remain coherent during repeat satellite over-passes, which can be exploited for interferometric SAR (InSAR measurements to estimate changes in water levels and water topography. InSAR results also suggest that coherence change detection (CCD might be applied to wetland monitoring applications. This study examines wetland vegetation characteristics that lead to coherence in RADARSAT-2 InSAR data of an area in eastern Canada with many small wetlands, and determines the annual variation in the coherence of these wetlands using multi-temporal radar data. The results for a three-year period demonstrate that most swamps and marshes maintain coherence throughout the ice-/snow-free time period for the 24-day repeat cycle of RADARSAT-2. However, open water areas without emergent aquatic vegetation generally do not have suitable coherence for CCD or InSAR water level estimation. We have found that wetlands with tree cover exhibit the highest coherence and the least variance; wetlands with herbaceous cover exhibit high coherence, but also high variability of coherence; and wetlands with shrub cover exhibit high coherence, but

  1. Can solvent induced surface modifications applied to screen-printed platforms enhance their electroanalytical performance?

    Science.gov (United States)

    Blanco, Elias; Foster, Christopher W; Cumba, Loanda R; do Carmo, Devaney R; Banks, Craig E

    2016-04-25

    In this paper the effect of solvent induced chemical surface enhancements upon graphitic screen-printed electrodes (SPEs) is explored. Previous literature has indicated that treating the working electrode of a SPE with the solvent N,N-dimethylformamide (DMF) offers improvements within the electroanalytical response, resulting in a 57-fold increment in the electrode surface area compared to their unmodified counterparts. The protocol involves two steps: (i) the SPE is placed into DMF for a selected time, and (ii) it is cured in an oven at a selected time and temperature. Beneficial electroanalytical outputs are reported to be due to the increased surface area attributed to the binder within the bulk surface of the SPEs dissolving out during the immersion step (step i). We revisit this exciting concept and explore these solvent induced chemical surface enhancements using edge- and basal-plane like SPEs and a new bespoke SPE, utilising the solvent DMF and explore, in detail, the parameters utilised in steps (i) and (ii). The electrochemical performance following steps (i) and (ii) is evaluated using the outer-sphere redox probe hexaammineruthenium(iii) chloride/0.1 M KCl, where it is found that the largest improvement is obtained using DMF with an immersion time of 10 minutes and a curing time of 30 minutes at 100 °C. Solvent induced chemical surface enhancement upon the electrochemical performance of SPEs is also benchmarked in terms of their electroanalytical sensing of NADH (dihydronicotinamide adenine dinucleotide reduced form) and capsaicin both of which are compared to their unmodified SPE counterparts. In both cases, it is apparent that a marginal improvement in the electroanalytical sensitivity (i.e. gradient of calibration plots) of 1.08-fold and 1.38-fold are found respectively. Returning to the original exciting concept, interestingly it was found that when a poor experimental technique was employed, only then significant increases within the working

  2. Adaptive tool servo diamond turning for enhancing machining efficiency and surface quality of freeform optics.

    Science.gov (United States)

    Zhu, Zhiwei; To, Suet

    2015-08-10

    Fast tool servo/ slow tool servo (FTS/STS) diamond turning is a very promising technique for the generation of freeform optics. However, the currently adopted constant scheme for azimuth sampling and side-feeding motion possesses no adaptation to surface shape variation, leading to the non-uniform surface quality and low machining efficiency. To overcome this defect, this paper reports on a novel adaptive tool servo (ATS) diamond turning technique which is essentially based on the novel two-degree-of-freedom (2-DOF) FTS/STS. In the ATS, the sampling interval and the side-feeding motion are actively controlled at any cutting point to adapt the machining process to shape variation of the desired surface, making both the sampling induced interpolation error and the side-feeding induced residual tool mark be within the desired tolerances. Characteristic of the required cutting motion suggests that besides the conventional z-axis servo motion, another servo motion along the x-axis synthesizing by the c-axis is mandatory for implementing the ATS. Comparative studies of surface generation of typical micro-structured surfaces in FTS/STS and ATS are thoroughly conducted both theoretically and experimentally. The result demonstrates that the ATS outperforms the FTS/STS with improved surface quality while simultaneously enhanced machining efficiency.

  3. Enhancing the Properties of Carbon and Gold Substrates by Surface Modification

    Energy Technology Data Exchange (ETDEWEB)

    Harnisch, Jennifer Anne [Iowa State Univ., Ames, IA (United States)

    2001-01-01

    The properties of both carbon and gold substrates are easily affected by the judicious choice of a surface modification protocol. Several such processes for altering surface composition have been published in literature. The research presented in this thesis primarily focuses on the development of on-column methods to modify carbon stationary phases used in electrochemically modulated liquid chromatography (EMLC). To this end, both porous graphitic carbon (PGC) and glassy carbon (GC) particles have been modified on-column by the electroreduction of arenediazonium salts and the oxidation of arylacetate anions (the Kolbe reaction). Once modified, the carbon stationary phases show enhanced chromatographic performance both in conventional liquid chromatographic columns and EMLC columns. Additionally, one may also exploit the creation of aryl films to by electroreduction of arenediazonium salts in the creation of nanostructured materials. The formation of mercaptobenzene film on the surface of a GC electrode provides a linking platform for the chemisorption of gold nanoparticles. After deposition of nanoparticles, the surface chemistry of the gold can be further altered by self-assembled monolayer (SAM) formation via the chemisorption of a second thiol species. Finally, the properties of gold films can be altered such that they display carbon-like behavior through the formation of benzenehexathiol (BHT) SAMs. BHT chemisorbs to the gold surface in a previously unprecedented planar fashion. Carbon and gold substrates can be chemically altered by several methodologies resulting in new surface properties. The development of modification protocols and their application in the analytical arena is considered herein.

  4. Surface modification of silicon-containing fluorocarbon films prepared by plasma-enhanced chemical vapor deposition

    Science.gov (United States)

    Jin, Yoonyoung; Desta, Yohannes; Goettert, Jost; Lee, G. S.; Ajmera, P. K.

    2005-07-01

    Surface modification of silicon-containing fluorocarbon (SiCF) films achieved by wet chemical treatments and through x-ray irradiation is examined. The SiCF films were prepared by plasma-enhanced chemical vapor deposition, using gas precursors of tetrafluoromethane and disilane. As-deposited SiCF film composition was analyzed by x-ray photoelectron spectroscopy. Surface modification of SiCF films utilizing n-lithiodiaminoethane wet chemical treatment is discussed. Sessile water-drop contact angle changed from 95°+/-2° before treatment to 32°+/-2° after treatment, indicating a change in the film surface characteristics from hydrophobic to hydrophilic. For x-ray irradiation on the SiCF film with a dose of 27.4 kJ/cm3, the contact angle of the sessile water drop changed from 95°+/-2° before radiation to 39°+/-3° after x-ray exposure. The effect of x-ray exposure on chemical bond structure of SiCF films is studied using Fourier transform infrared measurements. Electroless Cu deposition was performed to test the applicability of the surface modified films. The x-ray irradiation method offers a unique advantage in making possible surface modification in a localized area of high-aspect-ratio microstructures. Fabrication of a Ti-membrane x-ray mask is introduced here for selective surface modification using x-ray irradiation.

  5. Enhancing the Mechanical Durability of Icephobic Surfaces by Introducing Autonomous Self-Healing Function.

    Science.gov (United States)

    Zhuo, Yizhi; Håkonsen, Verner; He, Zhiwei; Xiao, Senbo; He, Jianying; Zhang, Zhiliang

    2018-03-27

    Ice accretion presents a severe risk for human safety. Although great efforts have been made for developing icephobic surfaces (the surface with an ice adhesion strength below 100 kPa), expanding the lifetime of state-of-the-art icephobic surfaces still remains a critical unsolved issue. Herein, a novel icephobic material is designed by integrating an interpenetrating polymer network (IPN) into an autonomous self-healing elastomer, which is applied in anti-icing for enhancing the mechanical durability. The molecular structure, surface morphology, mechanical properties, and durable icephobicity of the material were studied. The creep behaviors of the new icephobic material, which were absent in most relevant studies on self-healing materials, were also investigated in this work. Significantly, the material showed great potentials for anti-icing applications with an ultralow ice adhesion strength of 6.0 ± 0.9 kPa, outperforming many other icephobic surfaces. The material also exhibited an extraordinary durability, showing a very low long-term ice adhesion strength of ∼12.2 kPa after 50 icing/deicing cycles. Most importantly, the material was able to exhibit a self-healing property from mechanical damages in a sufficiently short time, which shed light on the longevity of icephobic surfaces in practical applications.

  6. Enhancement of vortex induced forces and motion through surface roughness control

    Science.gov (United States)

    Bernitsas, Michael M [Saline, MI; Raghavan, Kamaldev [Houston, TX

    2011-11-01

    Roughness is added to the surface of a bluff body in a relative motion with respect to a fluid. The amount, size, and distribution of roughness on the body surface is controlled passively or actively to modify the flow around the body and subsequently the Vortex Induced Forces and Motion (VIFM). The added roughness, when designed and implemented appropriately, affects in a predetermined way the boundary layer, the separation of the boundary layer, the level of turbulence, the wake, the drag and lift forces, and consequently the Vortex Induced Motion (VIM), and the fluid-structure interaction. The goal of surface roughness control is to increase Vortex Induced Forces and Motion. Enhancement is needed in such applications as harnessing of clean and renewable energy from ocean/river currents using the ocean energy converter VIVACE (Vortex Induced Vibration for Aquatic Clean Energy).

  7. Improving NOAA's NWLON Through Enhanced Data Inputs from NASA's Ocean Surface Topography

    Science.gov (United States)

    Guest, DeNeice C.

    2010-01-01

    This report assesses the benefit of incorporating NASA's OSTM (Ocean Surface Topography Mission) altimeter data (C- and Ku-band) into NOAA's (National Oceanic and Atmospheric Administration) NWLON (National Water Level Observation Network) DSS (Decision Support System). This data will enhance the NWLON DSS by providing additional inforrnation because not all stations collect all meteorological parameters (sea-surface height, ocean tides, wave height, and wind speed over waves). OSTM will also provide data where NWLON stations are not present. OSTM will provide data on seasurface heights for determining sea-level rise and ocean circulation. Researchers and operational users currently use satellite altimeter data products with the GSFCOO NASA data model to obtain sea-surface height and ocean circulation inforrnation. Accurate and tirnely inforrnation concerning sea-level height, tide, and ocean currents is needed to irnprove coastal tidal predictions, tsunarni and storm surge warnings, and wetland restoration.

  8. Thickness dependence of polydopamine thin films on detection sensitivity of surface plasmon-enhanced fluorescence biosensors

    Science.gov (United States)

    Toma, Mana; Tawa, Keiko

    2018-03-01

    A bioinspired polydopamine (PDA) coating is a good candidate for the rapid and cheap chemical modification of biosensor surfaces. Herein, we report the effect of PDA thickness on the detection sensitivity of a fluorescence biosensor utilizing surface plasmon-enhanced fluorescence. The thickness of PDA films was tuned by the incubation time of the dopamine solution and varied from 1 to 17 nm. The detection sensitivity was evaluated as the limit of detection (LOD) of a fluorescently labelled target analyte by a model immunoassay. The LOD was determined to be 1.6 pM for the thickest PDA film and was improved to 1.0 pM by reducing the thickness to the range from 1 to 5 nm, corresponding to the incubation time of 10 to 60 min. The experimental results indicate that the PDA coating is suitable for the surface functionalization of biosensors in mass production as it does not require precise control of the incubation time.

  9. Silver nanocluster films for glucose sensing by Surface Enhanced Raman Scattering (SERS

    Directory of Open Access Journals (Sweden)

    Raju Botta

    2016-07-01

    Full Text Available The detection of glucose by Surface Enhanced Raman Scattering (SERS is a challenging problem because glucose molecules have a small Raman scattering cross-section and they have a low affinity for adsorption on metal nanoparticle surfaces. In this study we used 2-Thienylboronic acid (2-TBA as a bridge or linker molecule between the metal surface and the glucose molecule and observed an intense Raman line at 986 cm−1 that was used to quantify the glucose concentration in the molar concentration range 1 μM–500 μM. A good correlation was observed between the intensity of this line and molar concentration of glucose. These results would find applications in the development of a non-invasive glucose sensor for diabetic patients using saliva as the body fluid instead of blood serum. Keywords: SERS, Nanoclusters, Raman Spectroscopy, 2-Thienylboronic acid, d-Glucose

  10. Surface-enhanced Raman spectroscopy with Au-nanoparticle substrate fabricated by using femtosecond pulse

    Science.gov (United States)

    Zhang, Wending; Li, Cheng; Gao, Kun; Lu, Fanfan; Liu, Min; Li, Xin; Zhang, Lu; Mao, Dong; Gao, Feng; Huang, Ligang; Mei, Ting; Zhao, Jianlin

    2018-05-01

    Au-nanoparticle (Au-NP) substrates for surface-enhanced Raman spectroscopy (SERS) were fabricated by grid-like scanning a Au-film using a femtosecond pulse. The Au-NPs were directly deposited on the Au-film surface due to the scanning process. The experimentally obtained Au-NPs presented local surface plasmon resonance effect in the visible spectral range, as verified by finite difference time domain simulations and measured reflection spectrum. The SERS experiment using the Au-NP substrates exhibited high activity and excellent substrate reproducibility and stability, and a clearly present Raman spectra of target analytes, e.g. Rhodamine-6G, Rhodamine-B and Malachite green, with concentrations down to 10‑9 M. This work presents an effective approach to producing Au-NP SERS substrates with advantages in activity, reproducibility and stability, which could be used in a wide variety of practical applications for trace amount detection.

  11. Custom Metal Occlusal Surface for Acrylic Resin Denture Teeth to Enhance Wear Resistance: A Case Report

    Directory of Open Access Journals (Sweden)

    Rizwan Ali Shivji

    2012-01-01

    Full Text Available Wear of the occlusal surface of the denture is a known fact which leads to subsequent changes in jaw relation, vertical dimension, loss of aesthetics, aged looks, and decrease in masticatory efficiency. Treatment modalities includes, change of denture set after a regular interval of 4-5 years, use of wear resistant denture teeth that includes wear resistant resin or porcelain teeth, teeth with cast metal occlusal surface, and altering occlusal contact areas of denture teeth by use of silver amalgam fillings. A case report of a patient who had increased tendency of occlusal wear was treated with custom made metal occlusal surface of denture teeth to enhance wear resistance and to improve the masticatory efficiency.

  12. N-Heterocyclic Carbenes as a Robust Platform for Surface-Enhanced Raman Spectroscopy.

    Science.gov (United States)

    DeJesus, Joseph F; Trujillo, Michael J; Camden, Jon P; Jenkins, David M

    2018-01-31

    Surface-enhanced Raman spectroscopy (SERS) underpins a wide range of commercial and fundamental applications. SERS often relies on ligands, usually thiols, bound to a noble metal surface. The difficulty of straightforward thiol synthesis combined with their instability on surfaces highlights the need for alternative ligand design. We present the first example of SERS utilizing N-heterocyclic carbene ligands. A general three step synthesis is presented for functionalized NHC-CO 2 adducts. These ligands are deposited on SERS-active gold film-over-nanosphere substrates (AuFONs) in solvent-free and base-free conditions, which prevents fouling. The resulting films are found to be robust and capable of postsynthetic modifications.

  13. Localized Surface Plasmons Enhanced Light Transmission into c-Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    Y. Premkumar Singh

    2013-01-01

    Full Text Available The paper investigates the light incoupling into c-Si solar cells due to the excitation of localized surface plasmon resonances in periodic metallic nanoparticles by finite-difference time-domain (FDTD technique. A significant enhancement of AM1.5G solar radiation transmission has been demonstrated by depositing nanoparticles of various metals on the upper surface of a semi-infinite Si substrate. Plasmonic nanostructures located close to the cell surface can scatter incident light efficiently into the cell. Al nanoparticles were found to be superior to Ag, Cu, and Au nanoparticles due to the improved transmission of light over almost the entire solar spectrum and, thus, can be a potential low-cost plasmonic metal for large-scale implementation of solar cells.

  14. On the heat transfer of enhancement condensation of vapor over the surface of an axisymmetric cylinder

    International Nuclear Information System (INIS)

    Xiou, W.J.; Ru, Y.A.; Mo, C.S.; Yi, H.S.

    1987-01-01

    The heat transfer of enhancement condensation of the vapor over the surface of an axisymmetric cylinder has been first studied theoretically in this paper. The problems of an axisymmetric cylinder are transformed into plate problems. The effects of some parameters on heat transfer coefficients of the vapor condensation over the surface of an axisymmetric cylinder have been discussed here. The heat transfer of the vapor condensation over an elliptical cylinder and an axisymmetric wing-shape cylinder has compared with the heat transfer of the vapor condensation over a tube surface. The conclusion is that the heat transfer of the vapor condensation over an elliptical cylinder and an axisymmetric wing-shape cylinder is greater than that over tubes

  15. Effective removal of trace thallium from surface water by nanosized manganese dioxide enhanced quartz sand filtration.

    Science.gov (United States)

    Huangfu, Xiaoliu; Ma, Chengxue; Ma, Jun; He, Qiang; Yang, Chun; Zhou, Jian; Jiang, Jin; Wang, Yaan

    2017-12-01

    Thallium (Tl) has drawn wide concern due to its high toxicity even at extremely low concentrations, as well as its tendency for significant accumulation in the human body and other organisms. The need to develop effective strategies for trace Tl removal from drinking water is urgent. In this study, the removal of trace Tl (0.5 μg L -1 ) by conventional quartz sand filtration enhanced by nanosized manganese dioxide (nMnO 2 ) has been investigated using typical surface water obtained from northeast China. The results indicate that nMnO 2 enhanced quartz sand filtration could remove trace Tl(I) and Tl(III) efficiently through the adsorption of Tl onto nMnO 2 added to a water matrix and onto nMnO 2 attached on quartz sand surfaces. Tl(III)-HA complexes might be responsible for higher residual Tl(III) in the effluent compared to residual Tl(I). Competitive Ca 2+ cations inhibit Tl removal to a certain extent because the Ca 2+ ions will occupy the Tl adsorption site on nMnO 2 . Moreover, high concentrations of HA (10 mgTOC L -1 ), which notably complexes with and dissolves nMnO 2 (more than 78%), resulted in higher residual Tl(I) and Tl(III). Tl(III)-HA complexes might also enhance Tl(III) penetration to a certain extent. Additionally, a higher pH level could enhance the removal of trace Tl from surface water. Finally, a slight increase of residual Tl was observed after backwash, followed by the reduction of the Tl concentration in the effluent to a "steady" state again. The knowledge obtained here may provide a potential strategy for drinking water treatment plants threatened by trace Tl. Copyright © 2017. Published by Elsevier Ltd.

  16. Enhanced osteointegration of medical titanium implant with surface modifications in micro/nanoscale structures

    Directory of Open Access Journals (Sweden)

    Liwen Lin

    2014-01-01

    Full Text Available Biomimetic design and substrate-based surface modification of medical implants will help to improve the integration of tissue to its material interfaces. Surface energy, composition, roughness, and topography all influence the biological responses of the implants, such as protein adsorption and cell adhesion, proliferation and differentiation. In the current study, different surface structures of Ti implants were constructed using facile surface techniques to create various micro-, nano-, and nano/micro composite scale topography. We have fabricated three types of hierarchical structures of TiO2 coating on Ti implants, including nanotube structure, nano sponge-like structure, and nano/micro nest-like structure. The osteointegration and biomechanical performance of the coated Ti screws were evaluated by histology and removal of torque force test in vivo. We found that the nano/micro nest-like and nanotube structured surface possessed better osteointegration ability. It indicated that the alkaline hydrothermally treated Ti substrate was the best for bone-implant integration in terms of all in vitro and in vivo testing parameters. The alkaline hydrothermally treated surface displayed a hydrophilic (contact angle value 5.92 ± 1.2, higher roughness (Ra value 911.3 ± 33.8 nm, higher specific surface area (8.26 ± 1.051 m2/g, and greater apatite inductivity. The electrochemical surface modification may become a powerful approach to enhance metal implant to bone integration in orthopaedic applications.

  17. SU-E-T-44: Angular Dependence of Surface Dose Enhancement Measured On Several Inhomogeneities Using Radiochromic EBT3 Films

    Energy Technology Data Exchange (ETDEWEB)

    Jansen, A; Schoenfeld, A; Poppinga, D; Chofor, N; Poppe, B [University of Oldenburg, Oldenburg (Germany); Pius Hospital Oldenburg, Oldenburg (Germany)

    2014-06-01

    Purpose: The quantification of the relative surface dose enhancement in dependence on the angle of incidence and the atomic number Z of the surface material. Methods: Experiments were performed with slabs made of aluminum, titanium, copper, silver, dental gold and lead. The metal slabs with equal sizes of 1.0×8.0×8.8mm{sup 3} were embedded in an Octavius 4D phantom (PTW Freiburg, Germany). Radiochromic EBT3 films were used to measure the surface dose for angles of incidence ranging from 0° to 90°. The setup with the metals slabs at the isocenter was irradiated with acceleration voltages of 6MV and 10MV. Water reference measurements were taken under equal conditions. Results: The surface dose enhancement is highest for angles of incidence below 30° and drops significantly for higher. The surface dose enhancement produced by lead and dental gold at 6MV showed a peak of 65%. At 90°, the surface dose enhancement dropped to 15% for both materials. The surface dose enhancements for silver, copper, titanium and aluminum were 45%, 32%, 22% and 12% at 0°, respectively. At an angle of incidence of 80°, the values dropped to 22%, 18%, 12% und 6%. The values for 10MV were very similar. Lead and dental gold showed peaks of 65% und 60%. Their values dropped to 18% at an angle of 90°. The surface dose enhancements for silver, copper, titanium and aluminum were 45%, 30%, 20% and 8% at 0°. At 80° the values dropped to 30%, 20%, 12% and 5%. A dependence of the magnitude of the surface dose enhancement on the atomic number of the surface material can be seen, which is in consistence with literature. Conclusion: The results show that the surface dose enhancements near implant materials with high Z-values should be taken into consideration in radio therapy, even when the angle of incidence is flat.

  18. SU-E-T-44: Angular Dependence of Surface Dose Enhancement Measured On Several Inhomogeneities Using Radiochromic EBT3 Films

    International Nuclear Information System (INIS)

    Jansen, A; Schoenfeld, A; Poppinga, D; Chofor, N; Poppe, B

    2014-01-01

    Purpose: The quantification of the relative surface dose enhancement in dependence on the angle of incidence and the atomic number Z of the surface material. Methods: Experiments were performed with slabs made of aluminum, titanium, copper, silver, dental gold and lead. The metal slabs with equal sizes of 1.0×8.0×8.8mm 3 were embedded in an Octavius 4D phantom (PTW Freiburg, Germany). Radiochromic EBT3 films were used to measure the surface dose for angles of incidence ranging from 0° to 90°. The setup with the metals slabs at the isocenter was irradiated with acceleration voltages of 6MV and 10MV. Water reference measurements were taken under equal conditions. Results: The surface dose enhancement is highest for angles of incidence below 30° and drops significantly for higher. The surface dose enhancement produced by lead and dental gold at 6MV showed a peak of 65%. At 90°, the surface dose enhancement dropped to 15% for both materials. The surface dose enhancements for silver, copper, titanium and aluminum were 45%, 32%, 22% and 12% at 0°, respectively. At an angle of incidence of 80°, the values dropped to 22%, 18%, 12% und 6%. The values for 10MV were very similar. Lead and dental gold showed peaks of 65% und 60%. Their values dropped to 18% at an angle of 90°. The surface dose enhancements for silver, copper, titanium and aluminum were 45%, 30%, 20% and 8% at 0°. At 80° the values dropped to 30%, 20%, 12% and 5%. A dependence of the magnitude of the surface dose enhancement on the atomic number of the surface material can be seen, which is in consistence with literature. Conclusion: The results show that the surface dose enhancements near implant materials with high Z-values should be taken into consideration in radio therapy, even when the angle of incidence is flat

  19. Tip-Selective Growth of Silver on Gold Nanostars for Surface-Enhanced Raman Scattering.

    Science.gov (United States)

    Zhang, Weiqing; Liu, Jie; Niu, Wenxin; Yan, Heng; Lu, Xianmao; Liu, Bin

    2018-04-19

    Nanogaps as "hot spots" with highly localized surface plasmon can generate ultrastrong electromagnetic fields. Superior to the exterior nanogaps obtained via aggregation and self-assembly, interior nanogaps within Au and Ag nanostructures give stable and reproducible surface-enhanced Raman scattering (SERS) signals. However, the synthesis of nanostructures with interior hot spots is still challenging because of the lack of high-yield strategies and clear design principles. Herein, gold-silver nanoclusters (Au-Ag NCs) with multiple interior hot spots were fabricated as SERS platforms via selective growth of Ag nanoparticles on the tips of Au nanostars (Au NSs). Furthermore, the interior gap sizes of Au-Ag NCs can be facilely tuned by changing the amount of AgNO 3 used. Upon 785 nm excitation, single Au-Ag NC 350 exhibits 43-fold larger SERS enhancement factor and the optimal signal reproducibility relative to single Au NS. The SERS enhancement factors and signal reproducibility of Au-Ag NCs increase with the decrease of gap sizes. Collectively, the Au-Ag NCs could serve as a flexible, reproducible, and active platform for SERS investigation.

  20. Rapid thyroid dysfunction screening based on serum surface-enhanced Raman scattering and multivariate statistical analysis

    Science.gov (United States)

    Tian, Dayong; Lü, Guodong; Zhai, Zhengang; Du, Guoli; Mo, Jiaqing; Lü, Xiaoyi

    2018-01-01

    In this paper, serum surface-enhanced Raman scattering and multivariate statistical analysis are used to investigate a rapid screening technique for thyroid function diseases. At present, the detection of thyroid function has become increasingly important, and it is urgently necessary to develop a rapid and portable method for the detection of thyroid function. Our experimental results show that, by using the Silmeco-based enhanced Raman signal, the signal strength greatly increases and the characteristic peak appears obviously. It is also observed that the Raman spectra of normal and anomalous thyroid function human serum are significantly different. Principal component analysis (PCA) combined with linear discriminant analysis (LDA) was used to diagnose thyroid dysfunction, and the diagnostic accuracy was 87.4%. The use of serum surface-enhanced Raman scattering technology combined with PCA-LDA shows good diagnostic performance for the rapid detection of thyroid function. By means of Raman technology, it is expected that a portable device for the rapid detection of thyroid function will be developed.

  1. Boron nitride nanosheets as improved and reusable substrates for gold nanoparticles enabled surface enhanced Raman spectroscopy

    KAUST Repository

    Cai, Qiran

    2015-01-01

    Atomically thin boron nitride (BN) nanosheets have been found to be excellent substrates for noble metal particles enabled surface enhanced Raman spectroscopy (SERS), thanks to their good adsorption of aromatic molecules, high thermal stability and weak Raman scattering. Faceted gold (Au) nanoparticles have been synthesized on BN nanosheets using a simple but controllable and reproducible sputtering and annealing method. The size and density of the Au particles can be controlled by sputtering time, current and annealing temperature etc. Under the same sputtering and annealing conditions, the Au particles on BN of different thicknesses show various sizes because the surface diffusion coefficients of Au depend on the thickness of BN. Intriguingly, decorated with similar morphology and distribution of Au particles, BN nanosheets exhibit better Raman enhancements than silicon substrates as well as bulk BN crystals. Additionally, BN nanosheets show no noticeable SERS signal and hence cause no interference to the Raman signal of the analyte. The Au/BN substrates can be reused by heating in air to remove the adsorbed analyte without loss of SERS enhancement. This journal is © the Owner Societies 2015.

  2. Oxygen Reduction Kinetics Enhancement on a Heterostructured Oxide Surface for Solid Oxide Fuel Cells

    KAUST Repository

    Crumlin, Ethan J.

    2010-11-04

    Heterostructured interfaces of oxides, which can exhibit transport and reactivity characteristics remarkably different from those of bulk oxides, are interesting systems to explore in search of highly active cathodes for the oxygen reduction reaction (ORR). Here, we show that the ORR of ∼85 nm thick La0.8Sr0.2CoO3-δ (LSC113) films prepared by pulsed laser deposition on (001)-oriented yttria-stabilized zirconia (YSZ) substrates is dramatically enhanced (∼3-4 orders of magnitude above bulk LSC113) by surface decorations of (La 0.5Sr0.5)2CoO4±δ (LSC214) with coverage in the range from ∼0.1 to ∼15 nm. Their surface and atomic structures were characterized by atomic force, scanning electron, and scanning transmission electron microscopy, and the ORR kinetics were determined by electrochemical impedance spectroscopy. Although the mechanism for ORR enhancement is not yet fully understood, our results to date show that the observed ORR enhancement can be attributed to highly active interfacial LSC113/LSC214 regions, which were shown to be atomically sharp. © 2010 American Chemical Society.

  3. Superhydrophobic Ag decorated ZnO nanostructured thin film as effective surface enhanced Raman scattering substrates

    Science.gov (United States)

    Jayram, Naidu Dhanpal; Sonia, S.; Poongodi, S.; Kumar, P. Suresh; Masuda, Yoshitake; Mangalaraj, D.; Ponpandian, N.; Viswanathan, C.

    2015-11-01

    The present work is an attempt to overcome the challenges in the fabrication of super hydrophobic silver decorated zinc oxide (ZnO) nanostructure thin films via thermal evaporation process. The ZnO nanowire thin films are prepared without any surface modification and show super hydrophobic nature with a contact angle of 163°. Silver is further deposited onto the ZnO nanowire to obtain nanoworm morphology. Silver decorated ZnO (Ag@ZnO) thin films are used as substrates for surface enhanced Raman spectroscopy (SERS) studies. The formation of randomly arranged nanowire and silver decorated nanoworm structure is confirmed using FESEM, HR-TEM and AFM analysis. Crystallinity and existence of Ag on ZnO are confirmed using XRD and XPS studies. A detailed growth mechanism is discussed for the formation of the nanowires from nanobeads based on various deposition times. The prepared SERS substrate reveals a reproducible enhancement of 3.082 × 107 M for Rhodamine 6G dye (R6G) for 10-10 molar concentration per liter. A higher order of SERS spectra is obtained for a contact angle of 155°. Thus the obtained thin films show the superhydrophobic nature with a highly enhanced Raman spectrum and act as SERS substrates. The present nanoworm morphology shows a new pathway for the construction of semiconductor thin films for plasmonic studies and challenges the orderly arranged ZnO nanorods, wires and other nano structure substrates used in SERS studies.

  4. Surface-enhanced Raman spectroscopy of urine by an ingenious near-infrared Raman spectrometer

    Science.gov (United States)

    Feng, Shangyuan; Chen, Weiwei; Li, Yongzeng; Chen, Guannan; Huang, Zufang; Liao, Xiaohua; Xie, Zhiming; Chen, Rong

    2007-11-01

    This paper demonstrates the potential of an elaborately devised near-infrared Raman system in analysis of urine. The broad band in the long-wavelength region of the electronic absorption spectra of the sol with added adsorbent at certain concentrations has been explained in terms of the aggregation of the colloidal silver particles. We have reported the surface-enhanced Raman (SERS) spectra of urine, and studied the silver solution enhanced effects on the urine Raman scattering. The Raman bands of human's urine was assigned to certain molecule vibrations. We have found that different donators have dissimilar SERS of urine in different physiological condition. Comparatively few studies have explored the ability of Raman spectroscopy for the analysis of urine acid. In the present report, we investigated the ability of surface enhanced Raman spectroscopy to measure uric acid in the human urine. The results suggested that the present Raman system holds considerable promise for practical use. Practical applications such as the quantitative medical examination of urine metabolites may also be feasible in the near future.

  5. A practical method to fabricate gold substrates for surface-enhanced Raman spectroscopy.

    Science.gov (United States)

    Tantra, Ratna; Brown, Richard J C; Milton, Martin J T; Gohil, Dipak

    2008-09-01

    We describe a practical method of fabricating surface-enhanced Raman spectroscopy (SERS) substrates based on dip-coating poly-L-lysine derivatized microscope slides in a gold colloidal suspension. The use of only commercially available starting materials in this preparation is particularly advantageous, aimed at both reducing time and the inconsistency associated with surface modification of substrates. The success of colloid deposition has been demonstrated by scanning electron microscopy (SEM) and the corresponding SERS response (giving performance comparable to the corresponding traditional colloidal SERS substrates). Reproducibility was evaluated by conducting replicate measurements across six different locations on the substrate and assessing the extent of the variability (standard deviation values of spectral parameters: peak width and height), in response to either Rhodamine 6G or Isoniazid. Of particular interest is the observation of how some peaks in a given spectrum are more susceptible to data variability than others. For example, in a Rhodamine 6G SERS spectrum, spectral parameters of the peak at 775 cm(-1) were shown to have a relative standard deviation (RSD) % of or=10%. This observation is best explained by taking into account spectral variations that arise from the effect of a chemisorption process and the local nature of chemical enhancement mechanisms, which affects the enhancement of some spectral peaks but not others (analogous to resonant Raman phenomenon).

  6. Enhanced osteoblast responses to poly ether ether ketone surface modified by water plasma immersion ion implantation.

    Science.gov (United States)

    Wang, Heying; Lu, Tao; Meng, Fanhao; Zhu, Hongqin; Liu, Xuanyong

    2014-05-01

    Poly ether ether ketone (PEEK) offers a set of characteristics superior for human implants; however, its application is limited by the bio-inert surface property. In this work, PEEK surface was modified using single step plasma immersion ion implantation (PIII) treatment with a gas mixture of water vapor as a plasma resource and argon as an ionization assistant. Field emission scanning electron microscopy, atomic force microscopy and X-ray photoelectron spectroscopy were used to investigate the microstructure and composition of the modified PEEK surface. The water contact angle and zeta-potential of the surfaces were also measured. Osteoblast precursor cells MC3T3-E1 and rat bone mesenchymal stem cells were cultured on the PEEK samples to evaluate their cytocompatibility. The obtained results show that the hydroxyl groups as well as a "ravined structure" are constructed on water PIII modified PEEK. Compared with pristine PEEK, the water PIII treated PEEK is more favorable for osteoblast adhesion, spreading and proliferation, besides, early osteogenic differentiation indicated by the alkaline phosphatase activity is also up-regulated. Our study illustrates enhanced osteoblast responses to the PEEK surface modified by water PIII, which gives positive information in terms of future biomedical applications. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Enhanced visible light photocatalytic property of red phosphorus via surface roughening

    International Nuclear Information System (INIS)

    Li, Weibing; Yue, Jiguang; Hua, Fangxia; Feng, Chang; Bu, Yuyu; Chen, Zhuoyuan

    2015-01-01

    Highlights: • Photocatalytic RhB degradation of red phosphorus was studied for the first time. • Surface rough can increase the photocatalysis reaction active sites. • Surface rough red phosphorus possesses high photocatalytic performance. • Surface rough red phosphorus has high industrial application value. - Abstract: Red phosphorus with rough surface (SRP) was prepared by catalyst-assisted hydrothermal synthesis using Co 2+ catalyst. The photocatalytic Rhodamine B (RhB) degradation of red phosphorus (RP) and SRP was studied for the first time in this work. Rough surface can enhance the dye adsorption ability of RP. About 75% RhB was absorbed by SRP after 30-min adsorption in 100 ml RhB solution with concentration of 10 mg l −1 in dark. After only 10 min of illumination by visible light, more than 95% RhB was degraded, indicating that SRP has a great application potential in the area of photocatalysis. The photocatalytic RhB degradation properties of RP are much weaker than those of SRP. The increase of the number of the active sites for the photocatalytic reactions, the electron mobility and the lifetime of the photogenerated electrons cause the significant improvement of the photocatalytic performance of SRP based on the experimental results obtained

  8. Enhanced magneto-optical imaging of internal stresses in the removed surface layer

    Science.gov (United States)

    Agalidi, Yuriy; Kozhukhar, Pavlo; Levyi, Sergii; Turbin, Dmitriy

    2015-10-01

    The paper describes a software method of reconstructing the state of the removed surface layer by visualising internal stresses in the underlying layers of the sample. Such a problem typically needs to be solved as part of forensic investigation that aims to reveal original marking of a sample with removed surface layer. For example, one may be interested in serial numbers of weapons or vehicles that had the surface layer of metal removed from the number plate. Experimental results of studying gradient internal stress fields in ferromagnetic sample using the NDI method of magneto-optical imaging (MOI) are presented. Numerical modelling results of internal stresses enclosed in the surface marking region are analysed and compared to the experimental results of magneto-optical imaging (MOI). MOI correction algorithm intended for reconstructing internal stress fields in the removed surface layer by extracting stresses retained by the underlying layers is described. Limiting ratios between parameters of a marking font are defined for the considered correction algorithm. Enhanced recognition properties for hidden stresses left by marking symbols are experimentally verified and confirmed.

  9. Observing reduction of 4-nitrobenzenthiol on gold nanoparticles in situ using surface-enhanced Raman spectroscopy.

    Science.gov (United States)

    Ren, Xiaoqian; Tan, Enzhong; Lang, Xiufeng; You, Tingting; Jiang, Li; Zhang, Hongyan; Yin, Penggang; Guo, Lin

    2013-09-14

    In this article, reduction of 4-nitrobenzenthiol (4-NBT) on Au nanoparticles (NPs) was characterized using surface-enhanced Raman scattering (SERS). Plasmon-driven chemical transformation from 4-NBT dimering into p,p'-dimercaptoazobenzene (DMAB) has been investigated on the surface of Au NPs. The laser power-dependent SERS spectra of 4-NBT on the surface of Au substrates were studied, and show that the laser power has an influence on the SERS signals of 4-NBT on Au NPs and production of DMAB by a plasmon-driven surface-catalyzed chemical reaction tends to be much easier under relative high laser power. Furthermore, we have used simple and efficient Au substrates (gold NPs with a size around 45 nm) exhibiting both catalytic properties and SERS activities to monitor the catalytic reaction of surface catalytic reaction process with borohydride solution. The experiments prove that the nitro-to-amino group conversion could be completed by borohydride at ambient conditions on Au substrates. Illuminated with high laser power, 4-NBT molecules and already formed DMAB molecules are further reduced into 4-aminobenzenthiol (4-ABT) by the addition of borohydride, While with low laser power 4-NBT molecules are transformed into 4-ABT with DMAB as the intermediate, which proves Au NPs are a mild and promising catalyst. Our studies might be helpful in extending the understanding of chemical reactions of 4-NBT and related research as well as providing a new strategy synthesis of azo dyes and anilines.

  10. Numerical and Experimental Investigation for Heat Transfer Enhancement by Dimpled Surface Heat Exchanger in Thermoelectric Generator

    Science.gov (United States)

    Wang, Yiping; Li, Shuai; Yang, Xue; Deng, Yadong; Su, Chuqi

    2016-03-01

    For vehicle thermoelectric exhaust energy recovery, the temperature difference between the heat exchanger and the coolant has a strong influence on the electric power generation, and ribs are often employed to enhance the heat transfer of the heat exchanger. However, the introduction of ribs will result in a large unwanted pressure drop in the exhaust system which is unfavorable for the engine's efficiency. Therefore, how to enhance the heat transfer and control the pressure drop in the exhaust system is quite important for thermoelectric generators (TEG). In the current study, a symmetrical arrangement of dimpled surfaces staggered in the upper and lower surfaces of the heat exchanger was proposed to augment heat transfer rates with minimal pressure drop penalties. The turbulent flow characteristics and heat transfer performance of turbulent flow over the dimpled surface in a flat heat exchanger was investigated by numerical simulation and temperature measurements. The heat transfer capacity in terms of Nusselt number and the pressure loss in terms of Fanning friction factors of the exchanger were compared with those of the flat plate. The pressure loss and heat transfer characteristics of dimples with a depth-to-diameter ratio ( h/D) at 0.2 were investigated. Finally, a quite good heat transfer performance with minimal pressure drop heat exchanger in a vehicle TEG was obtained. And based on the area-averaged surface temperature of the heat exchanger and the Seeback effect, the power generation can be improved by about 15% at Re = 25,000 compared to a heat exchanger with a flat surface.

  11. Enhancement of biocompatibility of nickel-titanium by laser surface modification technology

    Science.gov (United States)

    Ng, Ka Wai

    Nickel Titanium is a relatively new biomaterial that has attracted research interest for biomedical application. The good biocompatibility with specific functional properties of shape memory effect and superelasticity creates a smart material for medical applications. However, there are still concerns on nickel ion release of this alloy if it is going to be implanted for a long time. Nickel ion is carcinogenic and also causes allergic response and degeneration of muscle tissue. The subsequent release of Ni+ ions into the body system is fatal for the long term application of this alloy in the human body. To improve the long term biocompatibility and corrosion properties of NiTi, different surface treatment techniques have been investigated but no optimum technique has been established yet. This project will investigate the feasibility of applying laser surface alloying technique to improve the corrosion resistance and biocompatibility of NiTi in simulated body fluid condition. This thesis summarizes the result of laser surface modification of NiTi with Mo, Nb and Co using CO2 laser. The modified layer, which is free of microcracks and pores, acts as physical barrier to reduce nickel release and enhance the surface properties. The hardness values of the Mo-alloyed NiTi, Nb-alloyed NiTi and Co-alloyed NiTi surface were found to be three to four times harder than the NiTi substrate. Corrosion polarization tests also showed that the alloyed NiTi are significantly more resistant than the NiTi alloy. The release of Ni ions can be greatly reduced after laser surface alloying NiTi with Mo, Nb and Co. The improvement in wettability characteristics, the growth of the apatite on the specimen's surface and the adhesion of cell confirm the good biocompatibility after laser surface alloying. It is concluded that laser surface alloying is one of the potential technique not only to improve the corrosion resistance with low nickel release rate, but also retain the good

  12. Cohering power of quantum operations

    Energy Technology Data Exchange (ETDEWEB)

    Bu, Kaifeng, E-mail: bkf@zju.edu.cn [School of Mathematical Sciences, Zhejiang University, Hangzhou 310027 (China); Kumar, Asutosh, E-mail: asukumar@hri.res.in [Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211019 (India); Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094 (India); Zhang, Lin, E-mail: linyz@zju.edu.cn [Institute of Mathematics, Hangzhou Dianzi University, Hangzhou 310018 (China); Wu, Junde, E-mail: wjd@zju.edu.cn [School of Mathematical Sciences, Zhejiang University, Hangzhou 310027 (China)

    2017-05-18

    Highlights: • Quantum coherence. • Cohering power: production of quantum coherence by quantum operations. • Study of cohering power and generalized cohering power, and their comparison for differentmeasures of quantum coherence. • Operational interpretation of cohering power. • Bound on cohering power of a generic quantum operation. - Abstract: Quantum coherence and entanglement, which play a crucial role in quantum information processing tasks, are usually fragile under decoherence. Therefore, the production of quantum coherence by quantum operations is important to preserve quantum correlations including entanglement. In this paper, we study cohering power–the ability of quantum operations to produce coherence. First, we provide an operational interpretation of cohering power. Then, we decompose a generic quantum operation into three basic operations, namely, unitary, appending and dismissal operations, and show that the cohering power of any quantum operation is upper bounded by the corresponding unitary operation. Furthermore, we compare cohering power and generalized cohering power of quantum operations for different measures of coherence.

  13. Enhancement of the transverse Kerr magneto-optic effect by surface magnetoplasma waves

    International Nuclear Information System (INIS)

    Ferguson, P.E.; Stafsudd, O.M.; Wallis, R.F.

    1977-01-01

    The results of a theoretical and experimental investigation of the enhancement of the transverse Kerr magneto-optic effect (TKMOE) in a magnetic thin film due to the onset of surface plasma waves (SMPW) are presented. The magnetic thin film was vacuum deposited onto the base of a half-cylinder glass prism. SPW and SMPW induced at the film-air surface can resonant couple to the optical wave propagating parallel to the glass-film surface. In the presence of resonant coupling, the ordinary metallic reflectivity decreases and the normalized reflectivity difference (measure of the TKMOE) increases. Calculations have been made of the reflectivity and the normalized reflectivity difference as a function of angle of incidence for two iron thin films. In addition calculations have been made of the reflectivity and the normalized reflectivity difference as a function of photon energy and angle of incidence for two nickel films of 160A and 200A thickness. The normalized reflectivity difference and reflectivity have been measured for a thick nickel film and a thin nickel film (160A). An enhancement of the normalized reflectivity difference of 3x has been found. (Auth.)

  14. Surface mediated cooperative interactions of drugs enhance mechanical forces for antibiotic action

    Science.gov (United States)

    Ndieyira, Joseph W.; Bailey, Joe; Patil, Samadhan B.; Vögtli, Manuel; Cooper, Matthew A.; Abell, Chris; McKendry, Rachel A.; Aeppli, Gabriel

    2017-02-01

    The alarming increase of pathogenic bacteria that are resistant to multiple antibiotics is now recognized as a major health issue fuelling demand for new drugs. Bacterial resistance is often caused by molecular changes at the bacterial surface, which alter the nature of specific drug-target interactions. Here, we identify a novel mechanism by which drug-target interactions in resistant bacteria can be enhanced. We examined the surface forces generated by four antibiotics; vancomycin, ristomycin, chloroeremomycin and oritavancin against drug-susceptible and drug-resistant targets on a cantilever and demonstrated significant differences in mechanical response when drug-resistant targets are challenged with different antibiotics although no significant differences were observed when using susceptible targets. Remarkably, the binding affinity for oritavancin against drug-resistant targets (70 nM) was found to be 11,000 times stronger than for vancomycin (800 μM), a powerful antibiotic used as the last resort treatment for streptococcal and staphylococcal bacteria including methicillin-resistant Staphylococcus aureus (MRSA). Using an exactly solvable model, which takes into account the solvent and membrane effects, we demonstrate that drug-target interactions are strengthened by pronounced polyvalent interactions catalyzed by the surface itself. These findings further enhance our understanding of antibiotic mode of action and will enable development of more effective therapies.

  15. Surface enhanced raman spectroscopy on nucleic acids and related compounds adsorbed on colloidal silver particles

    Science.gov (United States)

    Kneipp, K.; Pohle, W.; Fabian, H.

    1991-04-01

    Various nucleic acids and related compounds have been investigated by surface enhanced Raman spectroscopy (SERS) on silver sol. The time delay between the addition of the various nucleic acids to the silver sol and the appearance of their SER spectra, i.e. the time needed by the various molecules to adsorb on an active site of the silver surface with an adsorption geometry which allows a SERS enhancement, shows strong differences. For instance, an immediate appearance of SER spectra has been found for DNA, whereas ribonucleic acids (RNAs) demonstrated a strong time delay (up to days) of the appearance of their SER spectra. This delay can be tentatively explained by the higher rigidity of RNA molecules compared with DNA. The more flexible DNA molecules are better adaptable to adsorption on silver than RNAs. The SER spectra of RNAs and DNAs showed strong changes within their relative line intensities as a function of time before they achieved stationary conditions, which indicates a protracted re-arrangement of the large molecules on the silver surface.

  16. Hollow Au/Ag nanostars displaying broad plasmonic resonance and high surface-enhanced Raman sensitivity

    Science.gov (United States)

    Garcia-Leis, Adianez; Torreggiani, Armida; Garcia-Ramos, Jose Vicente; Sanchez-Cortes, Santiago

    2015-08-01

    Bimetallic Au/Ag hollow nanostar (HNS) nanoparticles with different morphologies were prepared in this work. These nanoplatforms were obtained by changing the experimental conditions (concentration of silver and chemical reductors, hydroxylamine and citrate) and by using Ag nanostars as template nanoparticles (NPs) through galvanic replacement. The goal of this research was to create bimetallic Au/Ag star-shaped nanoparticles with advanced properties displaying a broader plasmonic resonance, a cleaner exposed surface, and a high concentration of electromagnetic hot spots on the surface provided by the special morphology of nanostars. The size, shape, and composition of Ag as well as their optical properties were studied by extinction spectroscopy, hyperspectral dark field microscopy, transmission and scanning electron microscopy (TEM and SEM), and energy dispersive X-ray spectroscopy (EDX). Finally, the surface-enhanced Raman scattering (SERS) activity of these HNS was investigated by using thioflavin T, a biomarker of the β-amyloid fibril formation, responsible for Alzheimer's disease. Lucigenin, a molecule displaying different SERS activities on Au and Ag, was also used to explore the presence of these metals on the NP surface. Thus, a relationship between the morphology, plasmon resonance and SERS activity of these new NPs was made.Bimetallic Au/Ag hollow nanostar (HNS) nanoparticles with different morphologies were prepared in this work. These nanoplatforms were obtained by changing the experimental conditions (concentration of silver and chemical reductors, hydroxylamine and citrate) and by using Ag nanostars as template nanoparticles (NPs) through galvanic replacement. The goal of this research was to create bimetallic Au/Ag star-shaped nanoparticles with advanced properties displaying a broader plasmonic resonance, a cleaner exposed surface, and a high concentration of electromagnetic hot spots on the surface provided by the special morphology of nanostars

  17. Partially coherent imaging and spatial coherence wavelets

    International Nuclear Information System (INIS)

    Castaneda, Roman

    2003-03-01

    A description of spatially partially coherent imaging based on the propagation of second order spatial coherence wavelets and marginal power spectra (Wigner distribution functions) is presented. In this dynamics, the spatial coherence wavelets will be affected by the system through its elementary transfer function. The consistency of the model with the both extreme cases of full coherent and incoherent imaging was proved. In the last case we obtained the classical concept of optical transfer function as a simple integral of the elementary transfer function. Furthermore, the elementary incoherent response function was introduced as the Fourier transform of the elementary transfer function. It describes the propagation of spatial coherence wavelets form each object point to each image point through a specific point on the pupil planes. The point spread function of the system was obtained by a simple integral of the elementary incoherent response function. (author)

  18. Three-dimensional hybrid silicon nanostructures for surface enhanced Raman spectroscopy based molecular detection

    Science.gov (United States)

    Vendamani, V. S.; Nageswara Rao, S. V. S.; Venugopal Rao, S.; Kanjilal, D.; Pathak, A. P.

    2018-01-01

    Three-dimensional silver nanoparticles decorated vertically aligned Si nanowires (Si NWs) are effective surface-enhanced Raman spectroscopy (SERS) substrates for molecular detection at low concentration levels. The length of Si NWs prepared by silver assisted electroless etching is increased with an increase in etching time, which resulted in the reduced optical reflection in the visible region. These substrates were tested and optimized by measuring the Raman spectrum of standard dye Rhodamine 6G (R6G) of 10 nM concentration. Further, effective SERS enhancements of ˜105 and ˜104 were observed for the cytosine protein (concentration of 50 μM) and ammonium perchlorate (oxidizer used in explosives composition with a concentration of 10 μM), respectively. It is established that these three-dimensional SERS substrates yielded considerably higher enhancement factors for the detection of R6G when compared to previous reports. The sensitivity can further be increased and optimized since the Raman enhancement was found to increase with an increase in the density of silver nanoparticles decorated on the walls of Si NWs.

  19. Direct visualization of fiber information by coherence.

    Science.gov (United States)

    Hlawitschka, Mario; Garth, Christoph; Tricoche, Xavier; Kindlmann, Gordon; Scheuermann, Gerik; Joy, Kenneth I; Hamann, Bernd

    2010-03-01

    The structure of fiber tracts in DT-MRI data presents a challenging problem for visualization and analysis. We derive visualization of such traces from a local coherence measure and achieve much improved visual segmentation. We introduce a coherence measure defined for fiber tracts. This quantitative assessment is based on infinitesimal deviations of neighboring tracts and allows identification and segmentation of coherent fiber regions. We use a hardware-accelerated implementation to achieve interactive visualization on slices and provide several approaches to visualize coherence information. Furthermore, we enhance existing techniques by combining them with coherence. We demonstrate our method on both a canine heart, where the myocardial structure is visualized, and a human brain, where we achieve detailed visualization of major and minor fiber bundles in a quality similar to and exceeding fiber clustering approaches. Our approach allows detailed and fast visualization of important anatomical structures in DT-MRI data sets.

  20. Polarization Dependence of Surface Enhanced Raman Scattering on a Single Dielectric Nanowire

    Directory of Open Access Journals (Sweden)

    Hua Qi

    2012-01-01

    Full Text Available Our measurements of surface enhanced Raman scattering (SERS on Ga2O3 dielectric nanowires (NWs core/silver composites indicate that the SERS enhancement is highly dependent on the polarization direction of the incident laser light. The polarization dependence of the SERS signal with respect to the direction of a single NW was studied by changing the incident light angle. Further investigations demonstrate that the SERS intensity is not only dependent on the direction and wavelength of the incident light, but also on the species of the SERS active molecule. The largest signals were observed on an NW when the incident 514.5 nm light was polarized perpendicular to the length of the NW, while the opposite phenomenon was observed at the wavelength of 785 nm. Our theoretical simulations of the polarization dependence at 514.5 nm and 785 nm are in good agreement with the experimental results.

  1. Surface modification induced enhanced CO2 sorption in cucurbit[6]uril, an organic porous material.

    Science.gov (United States)

    Mohan, Midhun; Suzuki, T; Nair, Akhil K; Pillai, Saju; Warrier, K G K; Hareesh, U S; Nair, Balagopal N; Gale, J D

    2017-09-27

    The CO 2 adsorption properties of an organic macrocycle, cucurbit[6]uril (CB[6]), have been evaluated through experimental and theoretical studies. Quantum mechanical calculations show that CB[6] is capable of adsorbing the CO 2 molecule selectively within its cavity relative to nitrogen. Adsorption experiments at 298 K and at 1 bar pressure gave a CO 2 adsorption value of 1.23 mmol g -1 for the unmodified material. Significant enhancements in the CO 2 adsorption capacity of the material were experimentally demonstrated through surface modification using physical and chemical methods. Ethanolamine (EA) modified CB[6] provided an excellent sorption selectivity value of 121.4 for CO 2 /N 2 at 323 K and is unique with respect to its discrimination potential between CO 2 and N 2 . The chemical nature of the interaction between CO 2 and amine is shown to be the primary mechanism for the enhanced CO 2 absorption performance.

  2. New Insight into Erythrocyte through In Vivo Surface-Enhanced Raman Spectroscopy

    DEFF Research Database (Denmark)

    Brazhe, Nadezda A.; Abdali, Salim; Brazhe, Alexey R.

    2009-01-01

    The article presents a noninvasive approach to the study of erythrocyte properties by means of a comparative analysis of signals obtained by surface-enhanced Raman spectroscopy (SERS) and resonance Raman spectroscopy (RS). We report step-by-step the procedure for preparing experimental samples...... containing erythrocytes in their normal physiological environment in a mixture of colloid solution with silver nanoparticles and the procedure for the optimization of SERS conditions to achieve high signal enhancement without affecting the properties of living erythrocytes. By means of three independent...... techniques, we demonstrate that under the proposed conditions a colloid solution of silver nanoparticles does not affect the properties of erythrocytes. For the first time to our knowledge, we describe how to use the SERS-RS approach to study two populations of hemoglobin molecules inside an intact living...

  3. Rapid, green synthesis and surface-enhanced Raman scattering effect of single-crystal silver nanocubes

    Science.gov (United States)

    Mao, Aiqin; Jin, Xia; Gu, Xiaolong; Wei, Xiaoqing; Yang, Guojing

    2012-08-01

    Single-crystal silver (Ag) nanocubes have been synthesized by a rapid and green method at room temperature by adding sodium hydroxide solution to the mixed solutions of silver nitrate, glucose and polyvinylpyrrolidone (PVP). The X-ray diffraction (XRD), ultraviolet-visible (UV-visible) and transmission electron microscopy (TEM) were used to characterize the phase composition and morphology. The results showed that the as-prepared particles were single-crystal Ag nanocubes with edge lengths of around 77 nm and a growing direction along {1 0 0} facets. As substrates for surface-enhanced Raman scattering (SERS) experiment on crystal violet (CV), the SERS enhancement factor of the as-prepared Ag nanocubes were measured to be 5.5 × 104, indicating potential applications in chemical and biological analysis.

  4. Enhancement of impact strength of poly (methyl methacrylate) with surface fine-tuned nano-silica

    International Nuclear Information System (INIS)

    Wen, Bin; Dong, Yixiao; Wu, Lili; Long, Chao; Zhang, Chaocan

    2015-01-01

    Highly dispersible nanoparticles in organic solvent always receive wide interests due to their compatibility with polymer materials. This paper reported a kind of isopropanol alcohol silica dispersion which obtained using a method of azeotropic distillation. The isopropanol alcohol dispersed silica (IPADS) were treated with coupling agents to fine-tune their surface properties. Polymethyl methacrylate (PMMA) was then used as a research object to test the compatibility between IPADS and polymer. UV-vis spectra indicate that IPADS would reach its high compatibility with PMMA if coupling with trimethoxypropylsilane (PTMS). Followed experiments on PMMA proved that the high compatibility can prominently enhance the impact strength about 30%. The results may provide reference both for nano-silica modification and better understanding of nano-enhanced materials. (paper)

  5. Electron-beam lithography of gold nanostructures for surface-enhanced Raman scattering

    International Nuclear Information System (INIS)

    Yue, Weisheng; Wang, Zhihong; Yang, Yang; Chen, Longqing; Syed, Ahad; Wong, Kimchong; Wang, Xianbin

    2012-01-01

    The fabrication of nanostructured substrates with precisely controlled geometries and arrangements plays an important role in studies of surface-enhanced Raman scattering (SERS). Here, we present two processes based on electron-beam lithography to fabricate gold nanostructures for SERS. One process involves making use of metal lift-off and the other involves the use of the plasma etching. These two processes allow the successful fabrication of gold nanostructures with various kinds of geometrical shapes and different periodic arrangements. 4-mercaptopyridine (4-MPy) and Rhodamine 6G (R6G) molecules are used to probe SERS signals on the nanostructures. The SERS investigations on the nanostructured substrates demonstrate that the gold nanostructured substrates have resulted in large SERS enhancement, which is highly dependent on the geometrical shapes and arrangements of the gold nanostructures. (paper)

  6. One-step microwave plasma enhanced chemical vapor deposition (MW-PECVD) for transparent superhydrophobic surface

    Science.gov (United States)

    Thongrom, Sukrit; Tirawanichakul, Yutthana; Munsit, Nantakan; Deangngam, Chalongrat

    2018-02-01

    We demonstrate a rapid and environmental friendly fabrication technique to produce optically clear superhydrophobic surfaces using poly (dimethylsiloxane) (PDMS) as a sole coating material. The inert PDMS chain is transformed into a 3-D irregular solid network through microwave plasma enhanced chemical vapor deposition (MW-PECVD) process. Thanks to high electron density in the microwave-activated plasma, coating can be done in just a single step with rapid deposition rate, typically much shorter than 10 s. Deposited layers show excellent superhydrophobic properties with water contact angles of ∼170° and roll-off angles as small as ∼3°. The plasma-deposited films can be ultrathin with thicknesses under 400 nm, greatly diminishing the optical loss. Moreover, with appropriate coating conditions, the coating layer can even enhance the transmission over the entire visible spectrum due to a partial anti-reflection effect.

  7. Surface-enhanced Raman imaging of cell membrane by a highly homogeneous and isotropic silver nanostructure

    Science.gov (United States)

    Zito, Gianluigi; Rusciano, Giulia; Pesce, Giuseppe; Dochshanov, Alden; Sasso, Antonio

    2015-04-01

    Label-free chemical imaging of live cell membranes can shed light on the molecular basis of cell membrane functionalities and their alterations under membrane-related diseases. In principle, this can be done by surface-enhanced Raman scattering (SERS) in confocal microscopy, but requires engineering plasmonic architectures with a spatially invariant SERS enhancement factor G(x, y) = G. To this end, we exploit a self-assembled isotropic nanostructure with characteristics of homogeneity typical of the so-called near-hyperuniform disorder. The resulting highly dense, homogeneous and isotropic random pattern consists of clusters of silver nanoparticles with limited size dispersion. This nanostructure brings together several advantages: very large hot spot density (~104 μm-2), superior spatial reproducibility (SD nanotoxicity issues. See DOI: 10.1039/c5nr01341k

  8. Electron-beam lithography of gold nanostructures for surface-enhanced Raman scattering

    KAUST Repository

    Yue, Weisheng

    2012-10-26

    The fabrication of nanostructured substrates with precisely controlled geometries and arrangements plays an important role in studies of surface-enhanced Raman scattering (SERS). Here, we present two processes based on electron-beam lithography to fabricate gold nanostructures for SERS. One process involves making use of metal lift-off and the other involves the use of the plasma etching. These two processes allow the successful fabrication of gold nanostructures with various kinds of geometrical shapes and different periodic arrangements. 4-mercaptopyridine (4-MPy) and Rhodamine 6G (R6G) molecules are used to probe SERS signals on the nanostructures. The SERS investigations on the nanostructured substrates demonstrate that the gold nanostructured substrates have resulted in large SERS enhancement, which is highly dependent on the geometrical shapes and arrangements of the gold nanostructures. © 2012 IOP Publishing Ltd.

  9. Electrochemical fabrication of two-dimensional palladium nanostructures as substrates for surface enhanced Raman scattering.

    Science.gov (United States)

    Li, Yin; Lu, Gewu; Wu, Xufeng; Shi, Gaoquan

    2006-12-07

    Two-dimensional palladium (Pd) nanostructures have been fabricated by electrochemical deposition of Pd onto an indium tin oxide glass substrate modified with a thin flat film of polypyrrole or a nanofibril film of polyaniline. The experimental results demonstrated that the morphology of Pd nanoparticles strongly depended on the properties of conducting polymers and the conditions of electrochemical deposition. Two-dimensional nanostructures composed of flower-like (consisting of staggered nanosheets) or pinecone-like Pd nanoparticles were successfully synthesized. They can be used as substrates for surface-enhanced Raman scattering after partly decomposing the polymer components by heating in air, and the enhancement factor of the substrate composed of flower-like Pd nanoparticles was measured to be as high as 105 for 4-mercaptopyridine.

  10. Controlled Clustering of Gold Nanoparticles using Solid-support for Surface-enhanced Raman Spectroscopic Probes

    International Nuclear Information System (INIS)

    Chang, Hyejin; Chae, Jinjoo; Jeong, Hong; Kang, Homan; Lee, Yoonsik

    2014-01-01

    We fabricated small clusters of gold nanoparticles by using solid-supported aggregation of gold nanoparticles. The fabricated Au nanoclusters consisting mainly of dimers showed homogeneous characteristics in cluster size and SERS intensity. The SERS enhancement of 4-ABT molecules in an effective area within 2-nm gap appeared to be approximately 10. Detachment process by ultrasonication was successively carried out in order to use the nanoclusters as SERS probes. The possibility of these clusters as SERS probe was proved in terms of signal and cluster size. Single molecule-level sensitivity of surface-enhanced Raman scattering (SERS) was known approximately fifteen years ago. Ever since there have been many different applications benefiting from the ultra-high sensitivity such as single molecule detection, chemical sensing and bio-molecular probes. Especially, SERS has drawn much attention in bio-multiplexing probes owing to its unique optical characteristics claiming extremely narrow bandwidth, high sensitivity of light signals, and non-bleaching feature

  11. Wafer-Scale Nanopillars Derived from Block Copolymer Lithography for Surface-Enhanced Raman Spectroscopy

    DEFF Research Database (Denmark)

    Li, Tao; Wu, Kaiyu; Rindzevicius, Tomas

    2016-01-01

    We report a novel nanofabrication process via block copolymer lithography using solvent vapor annealing. The nanolithography process is facile and scalable, enabling fabrication of highly ordered periodic patterns over entire wafers as substrates for surface-enhanced Raman spectroscopy (SERS......). Direct silicon etching with high aspect ratio templated by the block copolymer mask is realized without any intermediate layer or external precursors. Uniquely, an atomic layer deposition (ALD)-assisted method is introduced to allow reversing of the morphology relative to the initial pattern. As a result......, highly ordered silicon nanopillar arrays are fabricated with controlled aspect ratios. After metallization, the resulting nanopillar arrays are suitable for SERS applications. These structures readily exhibit an average SERS enhancement factor of above 108, SERS uniformities of 8.5% relative standard...

  12. Significantly improving trace thallium removal from surface waters during coagulation enhanced by nanosized manganese dioxide.

    Science.gov (United States)

    Huangfu, Xiaoliu; Ma, Chengxue; Ma, Jun; He, Qiang; Yang, Chun; Jiang, Jin; Wang, Yaan; Wu, Zhengsong

    2017-02-01

    Thallium (Tl) is an element of high toxicity and significant accumulation in human body. There is an urgent need for the development of appropriate strategies for trace Tl removal in drinking water treatment plants. In this study, the efficiency and mechanism of trace Tl (0.5 μg/L) removal by conventional coagulation enhanced by nanosized manganese dioxide (nMnO 2 ) were explored in simulated water and two representative surface waters (a river water and a reservoir water obtained from Northeast China). Experimental results showed that nMnO 2 significantly improve Tl(I) removal from selected waters. The removal efficiency was dramatically higher in the simulated water, demonstrating by less than 0.1 μg/L Tl residual. The enhancement of trace Tl removal in the surface waters decreased to a certain extent. Both adjusting water pH to alkaline condition and preoxidation of Tl(I) to Tl(III) benefit trace Tl removal from surface waters. Data also indicated that competitive cation of Ca 2+ decreased the efficiency of trace Tl removal, resulting from the reduction of Tl adsorption on nMnO 2 . Humic acid could largely low Tl removal efficiency during nMnO 2 enhanced coagulation processes. Trace elemental Tl firstly adsorbed on nMnO 2 and then removed accompanying with nMnO 2 settling. The information obtained in the present study may provide a potential strategy for drinking water treatment plants threatened by trace Tl. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Enhanced dissolved lipid production as a response to the sea surface warming

    Science.gov (United States)

    Novak, Tihana; Godrijan, Jelena; Pfannkuchen, Daniela Marić; Djakovac, Tamara; Mlakar, Marina; Baricevic, Ana; Tanković, Mirta Smodlaka; Gašparović, Blaženka

    2018-04-01

    The temperature increase in oceans reflects on marine ecosystem functioning and surely has consequences on the marine carbon cycle and carbon sequestration. In this study, we examined dissolved lipid, lipid classes and dissolved organic carbon (DOC) production in the northern Adriatic Sea, isolated diatom Chaetoceros pseudocurvisetus batch cultures grown in a wide temperature range (10-30 °C) and in contrasting nutrient regimes, phosphorus (P)-depleted and P-replete conditions. Additionally, lipids and DOC were analyzed in the northern Adriatic (NA) in two stations characterized with different P availability, occupied from February to August 2010 that covered a temperature range from 9.3 to 31.1 °C. To gain insight into factors governing lipid and lipid classes' production in the NA, apart from temperature (T), Chlorophyll a, phytoplankton community abundance and structure, nutrient concentrations were measured together with hydrographic parameters. We found enhanced accumulation of dissolved lipids, particulary glycolipids, with increasing T, especially during the highest in situ temperature. The effect of T on enhanced dissolved lipid release is much more pronounced under P-deplete conditions indicating that oligotrophic regions might be more vulnerable to T rise. Temperature between 25 and 30 °C is a threshold T range for C. pseudocurvisetus, at which a significant part of lipid production is directed toward the dissolved phase. Unlike monocultures, there are multiple factors influencing produced lipid composition, distribution and cycling in the NA that may counteract the T influence. The possible role of enhanced dissolved lipid concentration for carbon sequestration at elevated T is discussed. On the one hand, lipids are buoyant and do not sink, which enhances their retention at the surface layer. In addition, they are surface active, and therefore prone to adsorb on sinking particles, contributing to the C sequestration.

  14. Enhanced surface functionality via plasma modification and plasma deposition techniques to create more biologically relevant materials

    Science.gov (United States)

    Shearer, Jeffrey C.

    Functionalizing nanoparticles and other unusually shaped substrates to create more biologically relevant materials has become central to a wide range of research programs. One of the primary challenges in this field is creating highly functionalized surfaces without modifying the underlying bulk material. Traditional wet chemistry techniques utilize thin film depositions to functionalize nanomaterials with oxygen and nitrogen containing functional groups, such as --OH and --NHx. These functional groups can serve to create surfaces that are amenable to cell adhesion or can act as reactive groups for further attachment of larger structures, such as macromolecules or antiviral agents. Additional layers, such as SiO2, are often added between the nanomaterial and the functionalized coating to act as a barrier films, adhesion layers, and to increase overall hydrophilicity. However, some wet chemistry techniques can damage the bulk material during processing. This dissertation examines the use of plasma processing as an alternative method for producing these highly functionalized surfaces on nanoparticles and polymeric scaffolds through the use of plasma modification and plasma enhanced chemical vapor deposition techniques. Specifically, this dissertation will focus on (1) plasma deposition of SiO2 barrier films on nanoparticle substrates; (2) surface functionalization of amine and alcohol groups through (a) plasma co-polymerization and (b) plasma modification; and (3) the design and construction of plasma hardware to facilitate plasma processing of nanoparticles and polymeric scaffolds. The body of work presented herein first examines the fabrication of composite nanoparticles by plasma processing. SiOxC y and hexylamine films were coated onto TiO2 nanoparticles to demonstrate enhanced water dispersion properties. Continuous wave and pulsed allyl alcohol plasmas were used to produce highly functionalized Fe2 O3 supported nanoparticles. Specifically, film composition was

  15. Selectivity/Specificity Improvement Strategies in Surface-Enhanced Raman Spectroscopy Analysis

    Directory of Open Access Journals (Sweden)

    Feng Wang

    2017-11-01

    Full Text Available Surface-enhanced Raman spectroscopy (SERS is a powerful technique for the discrimination, identification, and potential quantification of certain compounds/organisms. However, its real application is challenging due to the multiple interference from the complicated detection matrix. Therefore, selective/specific detection is crucial for the real application of SERS technique. We summarize in this review five selective/specific detection techniques (chemical reaction, antibody, aptamer, molecularly imprinted polymers and microfluidics, which can be applied for the rapid and reliable selective/specific detection when coupled with SERS technique.

  16. Surface-enhanced Raman scattering for the detection of polycystic ovary syndrome.

    Science.gov (United States)

    Momenpour, Ali; Lima, Patrícia D A; Chen, Yi-An; Tzeng, Chii-Ruey; Tsang, Benjamin K; Anis, Hanan

    2018-02-01

    Polycystic ovary syndrome (PCOS) is a multi-factorial heterogeneous syndrome that affects many women of reproductive age. This work demonstrates how the surface-enhanced Raman scattering (SERS) technique can be used to differentiate between PCOS and non-PCOS patients. We determine that the use of SERS, in conjunction with partial least squares (PLS) and principal component analysis (PCA), allows us to detect PCOS in patient samples. Although the role of chemerin in the pathogenesis of PCOS patients is not clear, this work enables us to measure their chemerin levels using the PLS regression method.

  17. Click chemistry based biomolecular conjugation monitoring using surface-enhanced Raman spectroscopy mapping

    DEFF Research Database (Denmark)

    Palla, Mirko; Kumar, Shiv; Li, Zengmin

    2016-01-01

    We describe here a novel surface-enhanced Raman spectroscopy (SERS) based technique for monitoring the conjugation of small molecules by the well-known click reaction between an alkyne and azido moiety on the partner molecules. The monitoring principle is based on the loss of the characteristic...... such as bioconjugation, material science or drug discovery. Additionally, as an attractive advantage of this technique, no significant background signal is expected during the measurements, since these signals reside in a Raman silent region of 2000–2300 cm−1, where virtually all biological molecules are transparent....

  18. Use of silver nanoparticles to enhance surface plasmon-coupled emission (SPCE)

    OpenAIRE

    Chowdhury, Mustafa H.; Ray, Krishanu; Geddes, Chris D.; Lakowicz, Joseph R.

    2008-01-01

    We report that self-assembled monolayers of colloidal silver nanoparticles can increase the intensity of the surface plasmon-coupled emission (SPCE) signal from sulforhodamine 101 (S101). The S101 was spin coated on a glass slide coated with a layer of continuous silver, and a silica layer upon which the nanoparticle layer was self-assembled. Of the various colloid sizes studied, the 40 nm colloids showed both the highest enhancements in the SPCE signal and the largest extent of plasmon coupl...

  19. Surface Functionalization of Metal-Organic Framework Crystals with Catechol Coatings for Enhanced Moisture Tolerance.

    Science.gov (United States)

    Castells-Gil, Javier; Novio, Fernando; Padial, Natalia M; Tatay, Sergio; Ruíz-Molina, Daniel; Martí-Gastaldo, Carlos

    2017-12-27

    Robust catechol coatings for enhanced moisture tolerance were produced in one step by direct reaction of Hong Kong University of Science and Technology (HKUST) with synthetic catechols. We ascribe the rapid formation of homogeneous coatings around the metal-organic framework particles to the biomimetic catalytic activity of Cu(II) dimers in the external surface of the crystals. Use of fluorinated catechols results in hydrophobic, permeable coatings that protect HKUST from water degradation while retaining close to 100% of its original sorption capacity.

  20. Recent strategies toward microfluidic-based surface-enhanced Raman spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Týčová, Anna; Přikryl, Jan; Foret, František

    2017-01-01

    Roč. 38, č. 16 (2017), s. 1977-1987 ISSN 0173-0835 R&D Projects: GA ČR(CZ) GBP206/12/G014 Grant - others:AV ČR(CZ) MSM200311601 Program:Program na podporu mezinárodní spolupráce začínajících výzkumných pracovníků Institutional support: RVO:68081715 Keywords : microfluidics * nanoparticles * separation * Surface-enhanced Raman spectroscopy Subject RIV: CB - Analytical Chemistry, Separation OBOR OECD: Analytical chemistry Impact factor: 2.744, year: 2016