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Sample records for 3-dimensional time-resolved model

  1. 3-Dimensional Topographic Models for the Classroom

    NASA Technical Reports Server (NTRS)

    Keller, J. W.; Roark, J. H.; Sakimoto, S. E. H.; Stockman, S.; Frey, H. V.

    2003-01-01

    We have recently undertaken a program to develop educational tools using 3-dimensional solid models of digital elevation data acquired by the Mars Orbital Laser Altimeter (MOLA) for Mars as well as a variety of sources for elevation data of the Earth. This work is made possible by the use of rapid prototyping technology to construct solid 3-Dimensional models of science data. We recently acquired rapid prototyping machine that builds 3-dimensional models in extruded plastic. While the machine was acquired to assist in the design and development of scientific instruments and hardware, it is also fully capable of producing models of spacecraft remote sensing data. We have demonstrated this by using Mars Orbiter Laser Altimeter (MOLA) topographic data and Earth based topographic data to produce extruded plastic topographic models which are visually appealing and instantly engage those who handle them.

  2. 3-Dimensional Topographic Models for the Classroom

    NASA Technical Reports Server (NTRS)

    Keller, J. W.; Roark, J. H.; Sakimoto, S. E. H.; Stockman, S.; Frey, H. V.

    2003-01-01

    We have recently undertaken a program to develop educational tools using 3-dimensional solid models of digital elevation data acquired by the Mars Orbital Laser Altimeter (MOLA) for Mars as well as a variety of sources for elevation data of the Earth. This work is made possible by the use of rapid prototyping technology to construct solid 3-Dimensional models of science data. We recently acquired rapid prototyping machine that builds 3-dimensional models in extruded plastic. While the machine was acquired to assist in the design and development of scientific instruments and hardware, it is also fully capable of producing models of spacecraft remote sensing data. We have demonstrated this by using Mars Orbiter Laser Altimeter (MOLA) topographic data and Earth based topographic data to produce extruded plastic topographic models which are visually appealing and instantly engage those who handle them.

  3. Modeling Time Resolved Light Propagation Inside a Realistic Human Head Model

    PubMed Central

    Bazrafkan, Sh; Kazemi, K

    2014-01-01

    Background: Near infrared spectroscopy imaging is one of the new techniques used for investigating structural and functionality of different body tissues. This is done by injecting light into the medium and measuring the photon intensity at the surface of the tissue. Methods: In this paper the different medical applications, various imaging and simulation techniques of NIRS imaging is described. Each method is introduced and discussed. Then, the optimized model is prepared for numerical simulations. In this paper, the finite element method is used for solving the diffusion equation numerically. Results: Diffusion equation was solved for realistic human head model using finite element approach for a point light source and time resolved case. The photon intensity distribution in different head layers has been shown and the intensity orientation via the CSF layer has been illustrated. Conclusion: Simulating the photon transformation inside the tissue is essential for investigating the NIRS imaging technique. The finite element approach is a fast and accurate method for simulating this fact. The time resolved approach of this technique could illustrate the photon migration and intensity orientation in the tissue for time dependent light sources in tissues. PMID:25505770

  4. Incorporating 3-dimensional models in online articles.

    PubMed

    Cevidanes, Lucia H S; Ruellas, Antonio C O; Jomier, Julien; Nguyen, Tung; Pieper, Steve; Budin, Francois; Styner, Martin; Paniagua, Beatriz

    2015-05-01

    The aims of this article are to introduce the capability to view and interact with 3-dimensional (3D) surface models in online publications, and to describe how to prepare surface models for such online 3D visualizations. Three-dimensional image analysis methods include image acquisition, construction of surface models, registration in a common coordinate system, visualization of overlays, and quantification of changes. Cone-beam computed tomography scans were acquired as volumetric images that can be visualized as 3D projected images or used to construct polygonal meshes or surfaces of specific anatomic structures of interest. The anatomic structures of interest in the scans can be labeled with color (3D volumetric label maps), and then the scans are registered in a common coordinate system using a target region as the reference. The registered 3D volumetric label maps can be saved in .obj, .ply, .stl, or .vtk file formats and used for overlays, quantification of differences in each of the 3 planes of space, or color-coded graphic displays of 3D surface distances. All registered 3D surface models in this study were saved in .vtk file format and loaded in the Elsevier 3D viewer. In this study, we describe possible ways to visualize the surface models constructed from cone-beam computed tomography images using 2D and 3D figures. The 3D surface models are available in the article's online version for viewing and downloading using the reader's software of choice. These 3D graphic displays are represented in the print version as 2D snapshots. Overlays and color-coded distance maps can be displayed using the reader's software of choice, allowing graphic assessment of the location and direction of changes or morphologic differences relative to the structure of reference. The interpretation of 3D overlays and quantitative color-coded maps requires basic knowledge of 3D image analysis. When submitting manuscripts, authors can now upload 3D models that will allow readers to

  5. Incorporating 3-dimensional models in online articles

    PubMed Central

    Cevidanes, Lucia H. S.; Ruellasa, Antonio C. O.; Jomier, Julien; Nguyen, Tung; Pieper, Steve; Budin, Francois; Styner, Martin; Paniagua, Beatriz

    2015-01-01

    Introduction The aims of this article were to introduce the capability to view and interact with 3-dimensional (3D) surface models in online publications, and to describe how to prepare surface models for such online 3D visualizations. Methods Three-dimensional image analysis methods include image acquisition, construction of surface models, registration in a common coordinate system, visualization of overlays, and quantification of changes. Cone-beam computed tomography scans were acquired as volumetric images that can be visualized as 3D projected images or used to construct polygonal meshes or surfaces of specific anatomic structures of interest. The anatomic structures of interest in the scans can be labeled with color (3D volumetric label maps), and then the scans are registered in a common coordinate system using a target region as the reference. The registered 3D volumetric label maps can be saved in .obj, .ply, .stl, or .vtk file formats and used for overlays, quantification of differences in each of the 3 planes of space, or color-coded graphic displays of 3D surface distances. Results All registered 3D surface models in this study were saved in .vtk file format and loaded in the Elsevier 3D viewer. In this study, we describe possible ways to visualize the surface models constructed from cone-beam computed tomography images using 2D and 3D figures. The 3D surface models are available in the article’s online version for viewing and downloading using the reader’s software of choice. These 3D graphic displays are represented in the print version as 2D snapshots. Overlays and color-coded distance maps can be displayed using the reader’s software of choice, allowing graphic assessment of the location and direction of changes or morphologic differences relative to the structure of reference. The interpretation of 3D overlays and quantitative color-coded maps requires basic knowledge of 3D image analysis. Conclusions When submitting manuscripts, authors can

  6. Time-resolved transmittance: a comparison of the diffusion model approach with Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Rothfischer, Ramona; Grosenick, Dirk; Macdonald, Rainer

    2015-07-01

    We discuss the determination of optical properties of thick scattering media from measurements of time-resolved transmittance by diffusion theory using Monte Carlo simulations as a gold standard to model photon migration. Our theoretical and experimental investigations reveal differences between calculated distributions of times of flight (DTOFs) of photons from both models which result in an overestimation of the absorption and the reduced scattering coefficient by diffusion theory which becomes larger for small scattering coefficients. By introducing a temporal shift in the DTOFs obtained with the diffusion model as additional fit parameter, the deviation in the absorption coefficient can be compensated almost completely. If the scattering medium is additionally covered by transparent layers (e.g. glass plates) the deviation between the DTOFs from both models is even larger which mainly effects the determination of the reduced scattering coefficient by diffusion theory. A temporal shift improves the accuracy of the optical properties derived by diffusion theory in this case as well.

  7. In situ, time-resolved tomography for validating models of deformation in semi-solid alloys

    NASA Astrophysics Data System (ADS)

    Kareh, K. M.; Lee, P. D.; Gourlay, C. M.

    2012-07-01

    The development and validation of physically-based models of semi-solid alloy deformation requires experimental data on the microstructural response to load. In this work we present three-dimensional in situ synchrotron results of the indirect extrusion of semi-solid aluminium-copper alloys. Globular Al-15wt.% Cu specimens were deformed at solid fractions of approximately 0.7 during time-resolved x-ray tomography. Key phenomena of the response to load were observed and quantified, with a focus on particle translations and rotations, and the resulting displacement field. This example shows that crystal displacements can be quantified during semi-solid deformation of bulk specimens, allowing for datasets to be produced suitable for validating models of complex phenomena during semi-solid flow.

  8. Time-resolved simplified chemical kinetics modelling using computational singular perturbation

    NASA Technical Reports Server (NTRS)

    Lam, S. H.; Goussis, D. A.; Konopka, D.

    1989-01-01

    A CO-CH4-air reaction system is used to demonstrate the computational singular perturbation (CSP) method for deriving time-resolved simplified chemical kinetics models. CSP provides a programmable algorithm to group the given collection of elementary reactions into reaction groups which are ordered according to their speed. The concept of Importance Index k(m)exp s is introduced: k(m)exp s is defined to be a number between 0 and 1 which measures the importance of the m-th reaction group to the s-th reactant and can readily be computed from data generated by CSP. It is suggested that the robustness of the solutions of the reaction system can be qualitatively assessed by inspecting the Importance Index data.

  9. CAIPIRINHA-Dixon-TWIST (CDT)-volume-interpolated breath-hold examination (VIBE): a new technique for fast time-resolved dynamic 3-dimensional imaging of the abdomen with high spatial resolution.

    PubMed

    Michaely, Henrik J; Morelli, John N; Budjan, Johannes; Riffel, Philipp; Nickel, Dominik; Kroeker, Randall; Schoenberg, Stefan O; Attenberger, Ulrike I

    2013-08-01

    The purpose of this study was to assess the feasibility and image quality of a novel, highly accelerated T1-weighted sequence for time-resolved imaging of the abdomen during the first pass of contrast media transit using controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA) under sampling, view-sharing techniques, and Dixon water-fat separation (CAIPRINHA-Dixon-time-resolved imaging with interleaved stochastic trajectories-volumetric interpolated breath-hold examination [CDT-VIBE]). In this retrospective, institutional review board-approved study, 47 patients (median age, 62 years; 25 men, 22 women) scanned on a 3.0-T magnetic resonance system (Skyra; Siemens) were included. The CDT-VIBE (repetition time/echo time1/echo time2, 4.1/1.33/2.56 milliseconds; acquisition time, 29 seconds) was used in place of the standard arterial phase acquisition and started 15 seconds after the injection of 0.1 mmol/kg Gd-DOTA (Dotarem, Guerbet). Within 29 seconds, 14 high spatial resolution (1.2 × 1.2 × 3 mm) 3-dimensional data sets were acquired and reconstructed using view sharing (temporal resolution, 2.1 seconds). The CDT-VIBE images were evaluated independently by 2 blinded, experienced radiologists with regard to image quality and the number of hepatic arterial-dominant phases present on an ordinal 5-point scale (5, excellent; 1, nondiagnostic). Added diagnostic information with CDT-VIBE relative to portal venous phase VIBE was assessed. In all patients, CDT-VIBE measurements were successfully acquired. The image quality was diagnostic in 46 of the 47 patients. Both readers assessed the highest image quality present in the data sets with a median score of 4 (range, 3-5 for both readers; κ, 0.789) and the worst image quality with a median score of 3 (range, 1-4 for both readers; κ, 0.689). With a range between 1 and 8 (median, 5), hepatic arterial-dominant data sets (of the 14 acquired) were obtained in each case. There was an added diagnostic

  10. Model-based image reconstruction from time-resolved diffusion data

    SciTech Connect

    Saquib, S.S.; Hanson, K.M.; Cunningham, G.S.

    1997-02-01

    This paper addresses the issue of reconstructing the unknown field of absorption and scattering coefficients from time-resolved measurements of diffused light in a computationally efficient manner. The intended application is optical tomography, which has generated considerable interest in recent times. The inverse problem is posed in the Bayesian framework. The maximum {ital a posteriori} (MAP) estimate is used to compute the reconstruction. We use an edge- preserving generalized Gaussian Markov random field to model the unknown image. The diffusion model used for the measurements is solved forward in time using a finite-difference approach known as the alternating-directions implicit method. This method requires the inversion of a tridiagonal matrix at each time step and is therefore of O(N) complexity, where N is the dimensionality of the image. Adjoint differentiation is used to compute the sensitivity of the measurements with respect to the unknown image. The novelty of our method lies in the computation of the sensitivity since we can achieve it in O(N) time as opposed to O(N{sup 2}) time required by the perturbation approach. We present results using simulated data to show that the proposed method yields superior quality reconstructions with substantial savings in computation.

  11. Time-resolved transglottal pressure measurements in a scaled up vocal fold model

    NASA Astrophysics Data System (ADS)

    Ringenberg, Hunter; Krane, Michael; Rogers, Dylan; Misfeldt, Mitchel; Wei, Timothy

    2016-11-01

    Experimental measurements of flow through a scaled up dynamic human vocal fold model are presented. The simplified 10x scale vocal fold model from Krane, et al. (2007) was used to examine fundamental features of vocal fold oscillatory motion. Of particular interest was the temporal variation of transglottal pressure multiplied by the volume flow rate through the glottis throughout an oscillation cycle. Experiments were dynamically scaled to examine a range of frequencies, 100 - 200 Hz, corresponding to the male and female voice. By using water as the working fluid, very high resolution, both spatial and temporal resolution, was achieved. Time resolved movies of flow through symmetrically oscillating vocal folds will be presented. Both individual realizations as well as phase-averaged data will be shown. Key features, such as randomness and development time of the Coanda effect, vortex shedding, and volume flow rate data have been presented in previous APS-DFD meetings. This talk will focus more on the relation between the flow and aeroacoustics associated with vocal fold oscillations. Supported by the NIH.

  12. Steady-state and time resolved fluorescence analysis on tyrosine-histidine model compounds.

    PubMed

    Voicescu, Mariana; Heinrich, Martine; Hellwig, Petra

    2009-03-01

    Four model compounds, for a tyrosine-histidine covalent bonding, 2-(5-imidazolyl)-4-methylphenol (C-C bonding in ortho-position at the phenyl group); 2'-(1-imidazolyl)-4-methylphenol (C-N bonding in ortho'-position at the phenyl group); 2-(5-imidazolyl)-4-H-phenol and 2-(5-imidazolyl)-4-H-phenol, at physiological pH have been studied by UV-Vis absorption, steady-state and time resolved fluorescence spectroscopy. Their absorption and emission properties are presented and discussed. The photophysical properties depend on the para-substituted phenyl group as well as on C-C/C-N bonding in the Phenol-Imidazole linkage. The N position, N1-N3/N1-N4, in the imidazole group was found to be relevant. The results are discussed with relevance to the redox processes of tyrosine and to better understand the role of a tyrosine-histidine covalent linkage as found in cytochrome c oxidase.

  13. Validation of a time-resolved fluorescence spectroscopy apparatus in a rabbit atherosclerosis model

    NASA Astrophysics Data System (ADS)

    Fang, Qiyin; Jo, Javier A.; Papaioannou, Thanassis; Dorafshar, Amir; Reil, Todd; Qiao, Jian-Hua; Fishbein, Michael C.; Freischlag, Julie A.; Marcu, Laura

    2004-07-01

    Time-resolved laser-induced fluorescence spectroscopy (tr-LIFS) has been studied as a potential tool for in vivo diagnosis of atherosclerotic lesions. This study is to evaluate the potential of a compact fiber-optics based tr-LIFS instrument developed in our laboratory for in vivo analysis of atherosclerotic plaque composition. Time-resolved fluorescence spectroscopy studies were performed in vivo on fifteen New Zealand White rabbits (atherosclerotic: N=8, control: N=7). Time-resolved fluorescence spectra were acquired (range: 360-600 nm, increment: 5 nm, total acquisition time: 65 s) from normal aorta wall and lesions in the abdominal aorta. Data were analyzed in terms of fluorescence emission spectra and wavelength specific lifetimes. Following trichrome staining, tissue specimens were analyzed histopathologically in terms of intima/media thickness and biochemical composition (collagen, elastin, foam cells, and etc). Based on intimal thickness, the lesions were divided into thin and thick lesions. Each group was further separated into two categories: collagen rich lesions and foam cell rich lesions based on their biochemical composition. The obtained spectral and time domain fluorescence signatures were subsequently correlated to the histopathological findings. The results have shown that time-domain fluorescence spectral features can be used in vivo to separate atherosclerotic lesions from normal aorta wall as well discrimination within certain types of lesions.

  14. Modelling the effect of nuclear motion on the attosecond time-resolved photoelectron spectra of ethylene

    NASA Astrophysics Data System (ADS)

    Crawford-Uranga, A.; De Giovannini, U.; Mowbray, D. J.; Kurth, S.; Rubio, A.

    2014-06-01

    Using time-dependent density functional theory we examine the energy, angular and time-resolved photoelectron spectra (TRPES) of ethylene in a pump-probe setup. To simulate TRPES we expose ethylene to an ultraviolet femtosecond pump pulse, followed by a time delayed extreme ultraviolet probe pulse. Studying the photoemission spectra as a function of this delay provides us direct access to the dynamic evolution of the molecule’s electronic levels. Further, by including the nuclei’s motion, we provide direct chemical insight into the chemical reactivity of ethylene. These results show how angular and energy resolved TRPES could be used to directly probe electron and nucleus dynamics in molecules.

  15. Modelling Time-Resolved Two-Dimensional Electronic Spectroscopy of the Primary Photoisomerization Event in Rhodopsin

    PubMed Central

    2015-01-01

    Time-resolved two-dimensional (2D) electronic spectra (ES) tracking the evolution of the excited state manifolds of the retinal chromophore have been simulated along the photoisomerization pathway in bovine rhodopsin, using a state-of-the-art hybrid QM/MM approach based on multiconfigurational methods. Simulations of broadband 2D spectra provide a useful picture of the overall detectable 2D signals from the near-infrared (NIR) to the near-ultraviolet (UV). Evolution of the stimulated emission (SE) and excited state absorption (ESA) 2D signals indicates that the S1 → SN (with N ≥ 2) ESAs feature a substantial blue-shift only after bond inversion and partial rotation along the cis → trans isomerization angle, while the SE rapidly red-shifts during the photoinduced skeletal relaxation of the polyene chain. Different combinations of pulse frequencies are proposed in order to follow the evolution of specific ESA signals. These include a two-color 2DVis/NIR setup especially suited for tracking the evolution of the S1 → S2 transitions that can be used to discriminate between different photochemical mechanisms of retinal photoisomerization as a function of the environment. The reported results are consistent with the available time-resolved pump–probe experimental data, and may be used for the design of more elaborate transient 2D electronic spectroscopy techniques. PMID:24794143

  16. Quantification of joint inflammation in rheumatoid arthritis by time-resolved diffuse optical spectroscopy and tracer kinetic modeling

    NASA Astrophysics Data System (ADS)

    Ioussoufovitch, Seva; Morrison, Laura B.; Lee, Ting-Yim; St. Lawrence, Keith; Diop, Mamadou

    2015-03-01

    Rheumatoid arthritis (RA) is characterized by chronic synovial inflammation, which can cause progressive joint damage and disability. Diffuse optical spectroscopy (DOS) and imaging have the potential to become potent monitoring tools for RA. We devised a method that combined time-resolved DOS and tracer kinetics modeling to rapidly and reliably quantify blood flow in the joint. Preliminary results obtained from two animals show that the technique can detect joint inflammation as early as 5 days after onset.

  17. Time-resolved PIV measurements of the flow field in a stenosed, compliant arterial model

    NASA Astrophysics Data System (ADS)

    Geoghegan, P. H.; Buchmann, N. A.; Soria, J.; Jermy, M. C.

    2013-05-01

    Compliant (flexible) structures play an important role in several biological flows including the lungs, heart and arteries. Coronary heart disease is caused by a constriction in the artery due to a build-up of atherosclerotic plaque. This plaque is also of major concern in the carotid artery which supplies blood to the brain. Blood flow within these arteries is strongly influenced by the movement of the wall. To study these problems experimentally in vitro, especially using flow visualisation techniques, can be expensive due to the high-intensity and high-repetition rate light sources required. In this work, time-resolved particle image velocimetry using a relatively low-cost light-emitting diode illumination system was applied to the study of a compliant flow phantom representing a stenosed (constricted) carotid artery experiencing a physiologically realistic flow wave. Dynamic similarity between in vivo and in vitro conditions was ensured in phantom construction by matching the distensibility and the elastic wave propagation wavelength and in the fluid system through matching Reynolds ( Re) and Womersley number ( α) with a maximum, minimum and mean Re of 939, 379 and 632, respectively, and a α of 4.54. The stenosis had a symmetric constriction of 50 % by diameter (75 % by area). Once the flow rate reached a critical value, Kelvin-Helmholtz instabilities were observed to occur in the shear layer between the main jet exiting the stenosis and a reverse flow region that occurred at a radial distance of 0.34 D from the axis of symmetry in the region on interest 0-2.5 D longitudinally downstream from the stenosis exit. The instability had an axis-symmetric nature, but as peak flow rate was approached this symmetry breaks down producing instability in the flow field. The characteristics of the vortex train were sensitive not only to the instantaneous flow rate, but also to whether the flow was accelerating or decelerating globally.

  18. [3-Dimensional model reconstruction of penis and surrounding tissue].

    PubMed

    Wang, Rui-Heng; Cao, Chuan; Mei, Wen-Ming; Wang, Wen-Xian; Tan, Li-Wen; Li, Shi-Rong

    2012-07-01

    To evaluate the feasibility of 3-Dimensional (3-D) model reconstruction of penis and surrounding structures based on magnetic resonance images, which may provide the model building method for modeling surgery of individual penoplasty. Magnetic resonance (MR) images of penis with different imaging parameters were evaluated. With the surface rendering construction, the 3D virtual model was established by Amira software. The anatomical details imaging is better in T2-weighted fast spin-echo images with 3.0 mm slice thickness. The established model based on the MR images can show the soft-tissue, suspensory ligament of the penis. The suspensory ligament stretches between the pubic symphysis and the corpora cavernosa. The penile roots attach to inferior ramus of pubis. MR imaging provides enough anatomical information for modeling. It can be used for the development of model surgery system of individual penoplasty.

  19. Modeling long-range time-resolved charge-transfer within TDDFT: Insights from a 2-site lattice model

    NASA Astrophysics Data System (ADS)

    Fuks, Johanna; Maitra, Neepa

    2014-03-01

    It has been shown that approximate adiabatic TDDFT functionals dramatically fail to reproduce time-resolved long-range charge-transfer dynamics (LR-CTD). In order to decouple the impact of the adiabatic approximation and the choice of ground state (gs) functional it would be instructive to propagate using the adiabatically-exact (adia-ex) functional. Numerically this involves an iterative process at each time-step to find the gs potential for a given density, which converges badly for CTD due to regions of low density. To circumvent this, we use as model system an asymmetric 2-site Hubbard model with small hopping parameter, its small Hilbert space allows to perform a Levy-Lieb constrained search and find the exact gs Hartree-exchange-correlation (Hxc) functional. The later develops a sharp step feature in the long-range limit (limit of small hopping parameter). Both closed-shell to closed-shell and open-shell to open-shell LR-CT are investigated. By propagating the Kohn-Sham system in the presence of the exact gs Hxc functional under a resonant laser we are able to perform, for the first time, a fully self-consistent adia-ex propagation for CTD. We aknowledge financial support from the Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences ans Biosciences under Award DE-SC0008623 and NSF Grants CNS-0855217 and CNS-0958379.

  20. Time-resolved blood flow measurement in the in vivo mouse model by optical frequency domain imaging

    NASA Astrophysics Data System (ADS)

    Walther, Julia; Mueller, Gregor; Meissner, Sven; Cimalla, Peter; Homann, Hanno; Morawietz, Henning; Koch, Edmund

    2009-07-01

    In this study, we demonstrate that phase-resolved Doppler optical frequency domain imaging (OFDI) is very suitable to quantify the pulsatile blood flow within a vasodynamic measurement in the in vivo mouse model. For this, an OFDI-system with a read-out rate of 20 kHz and a center wavelength of 1320 nm has been used to image the time-resolved murine blood flow in 300 μμm vessels. Because OFDI is less sensitive to fringe washout due to axial sample motion, it is applied to analyze the blood flow velocities and the vascular dynamics in six-week-old C57BL/6 mice compared to one of the LDLR knockout strain kept under sedentary conditions or with access to voluntary wheel running. We have shown that the systolic as well as the diastolic phase of the pulsatile arterial blood flow can be well identified at each vasodynamic state. Furthermore, the changes of the flow velocities after vasoconstriction and -dilation were presented and interpreted in the entire physiological context. With this, the combined measurement of time-resolved blood flow and vessel diameter provides the basis to analyze the vascular function and its influence on the blood flow of small arteries of different mouse strains in response to different life styles.

  1. Time-resolved spectroscopy at surfaces and adsorbate dynamics: Insights from a model-system approach

    NASA Astrophysics Data System (ADS)

    Boström, Emil; Mikkelsen, Anders; Verdozzi, Claudio

    2016-05-01

    We introduce a model description of femtosecond laser induced desorption at surfaces. The substrate part of the system is taken into account as a (possibly semi-infinite) linear chain. Here, being especially interested in the early stages of dissociation, we consider a finite-size implementation of the model (i.e., a finite substrate), for which an exact numerical solution is possible. By time-evolving the many-body wave function, and also using results from a time-dependent density functional theory description for electron-nuclear systems, we analyze the competition between several surface-response mechanisms and electronic correlations in the transient and longer time dynamics under the influence of dipole-coupled fields. Our model allows us to explore how coherent multiple-pulse protocols can impact desorption in a variety of prototypical experiments.

  2. Time resolved diffuse optical spectroscopy with geometrically accurate models for bulk parameter recovery.

    PubMed

    Guggenheim, James A; Bargigia, Ilaria; Farina, Andrea; Pifferi, Antonio; Dehghani, Hamid

    2016-09-01

    A novel straightforward, accessible and efficient approach is presented for performing hyperspectral time-domain diffuse optical spectroscopy to determine the optical properties of samples accurately using geometry specific models. To allow bulk parameter recovery from measured spectra, a set of libraries based on a numerical model of the domain being investigated is developed as opposed to the conventional approach of using an analytical semi-infinite slab approximation, which is known and shown to introduce boundary effects. Results demonstrate that the method improves the accuracy of derived spectrally varying optical properties over the use of the semi-infinite approximation.

  3. Time resolved diffuse optical spectroscopy with geometrically accurate models for bulk parameter recovery

    PubMed Central

    Guggenheim, James A.; Bargigia, Ilaria; Farina, Andrea; Pifferi, Antonio; Dehghani, Hamid

    2016-01-01

    A novel straightforward, accessible and efficient approach is presented for performing hyperspectral time-domain diffuse optical spectroscopy to determine the optical properties of samples accurately using geometry specific models. To allow bulk parameter recovery from measured spectra, a set of libraries based on a numerical model of the domain being investigated is developed as opposed to the conventional approach of using an analytical semi-infinite slab approximation, which is known and shown to introduce boundary effects. Results demonstrate that the method improves the accuracy of derived spectrally varying optical properties over the use of the semi-infinite approximation. PMID:27699137

  4. Bio-physical modeling of time-resolved forward scattering by Listeria colonies

    NASA Astrophysics Data System (ADS)

    Bae, Euiwon; Banada, Padmapriya P.; Bhunia, Arun K.; Hirleman, E. Daniel

    2006-10-01

    We have developed a detection system and associated protocol based on optical forward scattering where the bacterial colonies of various species and strains growing on solid nutrient surfaces produced unique scatter signatures. The aim of the present investigation was to develop a bio-physical model for the relevant phenomena. In particular, we considered time-varying macroscopic morphological properties of the growing colonies and modeled the scattering using scalar diffraction theory. For the present work we performed detailed studies with three species of Listeria; L. innocua, L. monocytogenes, and L. ivanovii. The baseline experiments involved cultures grown on brain heart infusion (BHI) agar and the scatter images were captured every six hours for an incubation period of 42 hours. The morphologies of the colonies were studied by phase contrast microscopy, including measurement of the diameter of the colony. Growth curves, represented by colony diameter as a function of time, were compared with the time-evolution of scattering signatures. Similar studies were carried out with L. monocytogenes grown on different substrates. Non-dimensionalizing incubation time in terms of the time to reach stationary phase was effective in reducing the dimensionality of the model. Bio-physical properties of the colony such as diameter, bacteria density variation, surface curvature/profile, and transmission coefficient are important parameters in predicting the features of the forward scattering signatures. These parameters are included in a baseline model that treats the colony as a concentric structure with radial variations in phase modulation. In some cases azimuthal variations and random phase inclusions were included as well. The end result is a protocol (growth media, incubation time and conditions) that produces reproducible and distinguishable scatter patterns for a variety of harmful food borne pathogens in a short period of time. Further, the bio-physical model we

  5. Mandibular reconstruction using stereolithographic 3-dimensional printing modeling technology.

    PubMed

    Cohen, Adir; Laviv, Amir; Berman, Phillip; Nashef, Rizan; Abu-Tair, Jawad

    2009-11-01

    Mandibular reconstruction can be challenging for the surgeon wishing to restore its unique geometry. Reconstruction can be achieved with titanium bone plates followed by autogenous bone grafting. Incorporation of the bone graft into the mandible provides continuity and strength required for proper esthetics and function and permitting dental implant rehabilitation at a later stage. Precious time in the operating room is invested in plate contouring to reconstruct the mandible. Rapid prototyping technologies can construct physical models from computer-aided design via 3-dimensional (3D) printers. A prefabricated 3D model is achieved, which assists in accurate contouring of plates and/or planning of bone graft harvest geometry before surgery. The 2 most commonly used rapid prototyping technologies are stereolithography and 3D printing (3DP). Three-dimensional printing is advantageous to stereolithography for better accuracy, quicker printing time, and lower cost. We present 3 clinical cases based on 3DP modeling technology. Models were fabricated before the resection of mandibular ameloblastoma and were used to prepare bridging plates before the first stage of reconstruction. In 1 case, another model was fabricated and used as a template for iliac crest bone graft in the second stage of reconstruction. The 3DP technology provided a precise, fast, and cheap mandibular reconstruction, which aids in shortened operation time (and therefore decreased exposure time to general anesthesia, decreased blood loss, and shorter wound exposure time) and easier surgical procedure.

  6. Advanced receptor models for exploiting highly time-resolved data acquired in the EPA supersite preject

    NASA Astrophysics Data System (ADS)

    Ke, Haohao

    Receptor models have been widely used in air quality studies to identify pollution sources and estimate their contributions. A common problem for most current receptor models is insufficient consideration of realistic constraints such as can be obtained from emission inventories, chemical composition profiles of the sources, and the physics of plume dispersion. In addition, poor resolving of collinear sources was often found. With the high quality time-, composition-, and size-resolved measurements during the EPA Supersite project, efforts towards resolving nearby industrial sources were made by combinative use of Positive Matrix Factorization (PMF) and the Pseudo-Deterministic Receptor Model (PDRM). The PMF modeling of Baltimore data in September 2001 revealed coal-fired and oil-fired power plants (CFPP and OFPP, respectively) with significant cross contamination, as indicated by the high Se/Ni ratio in the OFPP profile. Nevertheless, the PMF results provided a good estimate of background and the PMF-constrained emission rates well seeded the trajectory-driven PDRM modeling. Using NOx as the tracer gas for chi/Q tuning, ultimately resolved emissions from individual stacks exhibited acceptable tracer ratios and the emission rates of metals generally agreed with the TRI estimates. This approach was later applied to two metal pollution episodes in St. Louis during in November 2001 and March 2002 and met a similar success. As NOx measurements were unavailable at those metal-production facilities, highly-specific tracer metals (i.e., Cd, Zn, and Cu) for the corresponding units were used to tune chi/Qs and their contributions were well resolved with the PMF-seeded PDRM. Opportunistically a PM2.5 excursion during a windless morning in November 2002 allowed the extraction of an in-situ profile of vehicular emissions in Baltimore. The profiles obtained by direct peak observation, windless model linear regression (WMA), PMF, and UNMIX were comparable and the WMA profile

  7. Experimental investigation and modeling of time resolved thrust of a flapping wing aircraft

    NASA Astrophysics Data System (ADS)

    Apker, Thomas B.

    This work presents a novel method of measuring the unsteady thrust of a hovering flapping wing vehicle and the development of phenomenological models to simulate it. The measurements were taken using a balance beam with the flapping wings mounted at one end and a counterweight plus an accelerometer mounted at the other. The trust axis of the flapping wings was mounted vertically, and the counterweight was adjusted to balance the weight and average thrust of the flapping wings. An accelerometer mounted above the counterweight measured the unsteady thrust. This method decoupled the force sensing element from the mass of the flapping wings, as opposed to standard force sensors that use a linear spring. This study showed that the spectral content of the flapping wings extended to 15 times the flapping frequency, well above the resonant frequency of the mass-spring-damper system formed by a load cell and flapping mechanism. High speed video of the wings was used to determine the motion of the flexible structure. This motion was used to develop phenomenological linear models of flapping wing thrust generation. The results show that this approach to linear modeling produces a system of equations that can be used for flight dynamics simulation and controller design.

  8. Time-resolved fluorescence spectroscopy of photosynthetic membranes: experiment and model simulations

    NASA Astrophysics Data System (ADS)

    Freiberg, Arvi; Pullerits, Tonu; Timpmann, Kou

    1990-05-01

    The singlet excitation transfer and trapping kinetics in photosynthetic membranes in case of low excitation intensities is studied by spectrally selective picosecond-time- domain fluorescence spectroscopy and by numerical integration of an appropriate system of equations. The essential features of our models are spectral heterogeneity of the light- harvesting antenna, inclusion of temperature effects, nonabsolute excitation traps, correlation between spectral and spatial parmeters. A reasonably good agreement between theoretical and experimental fluorescence decay kinetics for several purple photosynthetic bacteria has been achieved. This comparison gives several interesting numerical constants characterizing microscopic excitation transfer between different light-harvesting-antenna pigment-protein complexes towards the reaction centres. Some aspects of the experiment are also discussed.

  9. Atmospheric transport modelling of time resolved 133Xe emissions from the isotope production facility ANSTO, Australia.

    PubMed

    Schöppner, M; Plastino, W; Hermanspahn, N; Hoffmann, E; Kalinowski, M; Orr, B; Tinker, R

    2013-12-01

    The verification of the Comprehensive Nuclear-Test Ban Treaty (CTBT) relies amongst other things on the continuous and worldwide monitoring of radioxenon. The characterization of the existing and legitimate background, which is produced mainly by nuclear power plants and isotope production facilities, is of high interest to improve the capabilities of the monitoring network. However, the emissions from legitimate sources can usually only be estimated. For this paper historic source terms of (133)Xe emissions from the isotope production facility at ANSTO, Sydney, Australia, have been made available in a daily resolution. Based on these high resolution data, different source term sets with weekly, monthly and yearly time resolution have been compiled. These different sets are then applied together with atmospheric transport modelling (ATM) to predict the concentration time series at two radioxenon monitoring stations. The results are compared with each other in order to examine the improvement of the prediction capability depending on the used time resolution of the most dominant source term in the region.

  10. Development and Validation of a 3-Dimensional CFB Furnace Model

    NASA Astrophysics Data System (ADS)

    Vepsäläinen, Arl; Myöhänen, Karl; Hyppäneni, Timo; Leino, Timo; Tourunen, Antti

    At Foster Wheeler, a three-dimensional CFB furnace model is essential part of knowledge development of CFB furnace process regarding solid mixing, combustion, emission formation and heat transfer. Results of laboratory and pilot scale phenomenon research are utilized in development of sub-models. Analyses of field-test results in industrial-scale CFB boilers including furnace profile measurements are simultaneously carried out with development of 3-dimensional process modeling, which provides a chain of knowledge that is utilized as feedback for phenomenon research. Knowledge gathered by model validation studies and up-to-date parameter databases are utilized in performance prediction and design development of CFB boiler furnaces. This paper reports recent development steps related to modeling of combustion and formation of char and volatiles of various fuel types in CFB conditions. Also a new model for predicting the formation of nitrogen oxides is presented. Validation of mixing and combustion parameters for solids and gases are based on test balances at several large-scale CFB boilers combusting coal, peat and bio-fuels. Field-tests including lateral and vertical furnace profile measurements and characterization of solid materials provides a window for characterization of fuel specific mixing and combustion behavior in CFB furnace at different loads and operation conditions. Measured horizontal gas profiles are projection of balance between fuel mixing and reactions at lower part of furnace and are used together with both lateral temperature profiles at bed and upper parts of furnace for determination of solid mixing and combustion model parameters. Modeling of char and volatile based formation of NO profiles is followed by analysis of oxidizing and reducing regions formed due lower furnace design and mixing characteristics of fuel and combustion airs effecting to formation ofNO furnace profile by reduction and volatile-nitrogen reactions. This paper presents

  11. Time-resolved functional analysis of acute impairment of frataxin expression in an inducible cell model of Friedreich ataxia

    PubMed Central

    Poburski, Dörte; Boerner, Josefine Barbara; Koenig, Michel; Ristow, Michael

    2016-01-01

    ABSTRACT Friedreich ataxia is a neurodegenerative disease caused by a GAA triplet repeat expansion in the first intron of the frataxin gene, which results in reduced expression levels of the corresponding protein. Despite numerous animal and cellular models, therapeutic options that mechanistically address impaired frataxin expression are lacking. Here, we have developed a new mammalian cell model employing the Cre/loxP recombination system to induce a homozygous or heterozygous frataxin knockout in mouse embryonic fibroblasts. Induction of Cre-mediated disruption by tamoxifen was successfully tested on RNA and protein levels. After loss of frataxin protein, cell division, aconitase activity and oxygen consumption rates were found to be decreased, while ROS production was increased in the homozygous state. By contrast, in the heterozygous state no such changes were observed. A time-resolved analysis revealed the loss of aconitase activity as an initial event after induction of complete frataxin deficiency, followed by secondarily elevated ROS production and a late increase in iron content. Initial impairments of oxygen consumption and ATP production were found to be compensated in the late state and seemed to play a minor role in Friedreich ataxia pathophysiology. In conclusion and as predicted from its proposed role in iron sulfur cluster (ISC) biosynthesis, disruption of frataxin primarily causes impaired function of ISC-containing enzymes, whereas other consequences, including elevated ROS production and iron accumulation, appear secondary. These parameters and the robustness of the newly established system may additionally be used for a time-resolved study of pharmacological candidates in a HTS manner. PMID:27106929

  12. Establishment of Magnetic Microparticles-Assisted Time-Resolved Fluoroimmunoassay for Determinating Biomarker Models in Human Serum

    PubMed Central

    Ren, Zhi-Qi; Liu, Tian-Cai; Zhuang, Si-Hui; Lin, Guan-Feng; Hou, Jing-Yuan; Wu, Ying-Song

    2015-01-01

    In order to early screen and detect suspected biomarkers from pathogens and the human body itself, tracers or reaction strategies that can act as signal enhancers have been proposed forth at purpose. In this paper, we discussed the applicability of magnetic microparticles-assisted time-resolved fluoroimmunoassay (MMPs-TRFIA) for sensitive determination of potential analytes. Hepatitis B e antigen, antibody to hepatitis B surface antigen and free triiodothyronine were used as biomarker models to explore the reliability of the method. By coupling with bioprobes, MMPs were used as immunoassay carriers to capture target molecules. Under optimal condition, assay performance, including accuracy, precision and specificity, was outstanding and demonstrated satisfactory. To further evaluate the performance of the MMPs-TRFIA in patients, a total of 728 serum samples from hospital were analyzed for three biomarkers in parallel with the proposed method and chemiluminescence immunoassay kit commercially available. Fairly good agreements are obtained between the two methods via data analysis. Not only that but the reliability of MMPs-TRFIA has also been illustrated by three different reaction models. It is confirmed that the novel method modified with MMPs has been established and showed great potential applications in both biological detection and clinical diagnosis, including big molecule protein and low molecular weight haptens. PMID:26103625

  13. Time-resolved non-sequential ray-tracing modelling of non-line-of-sight picosecond pulse LIDAR

    NASA Astrophysics Data System (ADS)

    Sroka, Adam; Chan, Susan; Warburton, Ryan; Gariepy, Genevieve; Henderson, Robert; Leach, Jonathan; Faccio, Daniele; Lee, Stephen T.

    2016-05-01

    The ability to detect motion and to track a moving object that is hidden around a corner or behind a wall provides a crucial advantage when physically going around the obstacle is impossible or dangerous. One recently demonstrated approach to achieving this goal makes use of non-line-of-sight picosecond pulse laser ranging. This approach has recently become interesting due to the availability of single-photon avalanche diode (SPAD) receivers with picosecond time resolution. We present a time-resolved non-sequential ray-tracing model and its application to indirect line-of-sight detection of moving targets. The model makes use of the Zemax optical design programme's capabilities in stray light analysis where it traces large numbers of rays through multiple random scattering events in a 3D non-sequential environment. Our model then reconstructs the generated multi-segment ray paths and adds temporal analysis. Validation of this model against experimental results is shown. We then exercise the model to explore the limits placed on system design by available laser sources and detectors. In particular we detail the requirements on the laser's pulse energy, duration and repetition rate, and on the receiver's temporal response and sensitivity. These are discussed in terms of the resulting implications for achievable range, resolution and measurement time while retaining eye-safety with this technique. Finally, the model is used to examine potential extensions to the experimental system that may allow for increased localisation of the position of the detected moving object, such as the inclusion of multiple detectors and/or multiple emitters.

  14. SVD-aided pseudo principal-component analysis: A new method to speed up and improve determination of the optimum kinetic model from time-resolved data

    PubMed Central

    Oang, Key Young; Yang, Cheolhee; Muniyappan, Srinivasan; Kim, Jeongho; Ihee, Hyotcherl

    2017-01-01

    Determination of the optimum kinetic model is an essential prerequisite for characterizing dynamics and mechanism of a reaction. Here, we propose a simple method, termed as singular value decomposition-aided pseudo principal-component analysis (SAPPA), to facilitate determination of the optimum kinetic model from time-resolved data by bypassing any need to examine candidate kinetic models. We demonstrate the wide applicability of SAPPA by examining three different sets of experimental time-resolved data and show that SAPPA can efficiently determine the optimum kinetic model. In addition, the results of SAPPA for both time-resolved X-ray solution scattering (TRXSS) and transient absorption (TA) data of the same protein reveal that global structural changes of protein, which is probed by TRXSS, may occur more slowly than local structural changes around the chromophore, which is probed by TA spectroscopy. PMID:28405591

  15. Infrared long nanosecond laser pulse ablation of silicon: Integrated two-dimensional modeling and time-resolved experimental study

    NASA Astrophysics Data System (ADS)

    Tao, Sha; Zhou, Yun; Wu, Benxin; Gao, Yibo

    2012-07-01

    Nanosecond (ns) laser ablation may provide good solutions to many industrial silicon micromachining applications. However, most of the previous work is on lasers in ultraviolet (UV) or visible spectral ranges, and ns laser ablation of silicon at the infrared (IR) wavelength has not been well understood, particularly for long ns pulses with durations on the order of ∼100 ns. IR ns lasers often have lower costs and less external energy consumption for the same laser energy output than UV or visible lasers, which is desirable for many practical applications. This paper aims to understand the mechanism of IR ns laser ablation of silicon, by combining time-resolved experimental observations with physics-based modeling study. The observation is through a ns-gated intensified charged-coupled devices (ICCD) camera coupled with a microscope tube, while the model is based on two-dimensional (2D) gas dynamic equations for the gaseous phases coupled with the condensed phase heat transfer equation through the Knudsen layer relations. The research shows that the material removal mechanism under the studied laser ablation conditions is surface vaporization in the early stage (yielding a plasma plume above the target), followed by subsequent liquid ejection. The measured plasma front propagation matches reasonably well with the model prediction. The experimentally observed spatial distribution of the plasma radiation intensity is consistent with and has been understood through the model. The study also shows that the observed liquid ejection is induced by the total surface pressure difference between the near-boundary region of the target melt pool and the other remaining region of the pool. The pressure difference is mainly due to the surface vaporization flux drop after laser pulse ends.

  16. Analyzing solution-phase time-resolved x-ray diffraction data by isolated-solute models

    SciTech Connect

    Lee, Jae Hyuk; Kim, Kyoung Hwan; Kim, Tae Kyu; Lee, Youhong; Ihee, Hyotcherl

    2006-11-07

    Extracting transient structural information of a solute from time-resolved x-ray diffraction (TRXD) data is not trivial because the signal from a solution contains not only the solute-only term as in the gas phase, but also solvent-related terms. To obtain structural insights, the diffraction signal in q space is often Fourier sine transformed (FT) into r space, and molecular dynamics (MD) simulation-aided signal decomposition into the solute, cage, and solvent terms has so far been indispensable for a clear-cut assignment of structural features. Here we present a convenient method of comparative structural analysis without involving MD simulations by incorporating only isolated-species models for the solute. FT is applied to both the experimental data and candidate isolated-solute models, and comparison of the correlation factors between the experimental FT and the model FTs can distinguish the best candidate among isolated-solute models for the reaction intermediates. The low q region whose influence by solvent-related terms is relatively high can be further excluded, and this mode of truncated Fourier transform (TFT) improves the correlation factors and facilitates the comparison. TFT analysis has been applied to TRXD data on the photodissociation of C{sub 2}H{sub 4}I{sub 2} in two different solvents (methanol and cyclohexane), HgI{sub 2} in methanol, and I{sub 3}{sup -} in methanol excited at 267 nm. The results are consistent with previous conclusions for C{sub 2}H{sub 4}I{sub 2} in methanol and HgI{sub 2} in methanol, and the new TRXD data reveal that the C{sub 2}H{sub 4}I transient radical has a bridged structure in cyclohexane and I{sub 3}{sup -} in methanol decomposes into I+I{sub 2}{sup -} upon irradiation at 267 nm. This TFT method should greatly simplify the analysis because it bypasses MD simulations.

  17. Time resolved analysis of Fermi gamma-ray bursts with fast-and slow-cooled synchrotron photon models

    SciTech Connect

    Burgess, J. M.; Preece, R. D.; Connaughton, V.; Briggs, M. S.; Goldstein, A.; Bhat, P. N.; Greiner, J.; Gruber, D.; Kienlin, A.; Kouveliotou, C.; McGlynn, S.; Meegan, C. A.; Paciesas, W. S.; Rau, A.; Xiong, S.; Axelsson, M.; Baring, M. G.; Dermer, C. D.; Iyyani, S.; Kocevski, D.; Omodei, N.; Ryde, F.; Vianello, G.

    2014-02-27

    Time-resolved spectroscopy is performed on eight bright, long gamma-ray bursts (GRBs) dominated by single emission pulses that were observed with the Fermi Gamma-Ray Space Telescope. Fitting the prompt radiation of GRBs by empirical spectral forms such as the Band function leads to ambiguous conclusions about the physical model for the prompt radiation. Moreover, the Band function is often inadequate to fit the data. Therefore, the GRB spectrum is modeled with two emission components consisting of optically thin non-thermal synchrotron radiation from relativistic electrons and, when significant, thermal emission from a jet photosphere, which is represented by a blackbody spectrum. In order to produce an acceptable fit, the addition of a blackbody component is required in five out of the eight cases. We also find that the low-energy spectral index α is consistent with a synchrotron component with α = –0.81 ± 0.1. This value lies between the limiting values of α = –2/3 and α = –3/2 for electrons in the slow- and fast-cooling regimes, respectively, suggesting ongoing acceleration at the emission site. The blackbody component can be more significant when using a physical synchrotron model instead of the Band function, illustrating that the Band function does not serve as a good proxy for a non-thermal synchrotron emission component. The temperature and characteristic emission-region size of the blackbody component are found to, respectively, decrease and increase as power laws with time during the prompt phase. Additionally, we find that the blackbody and non-thermal components have separate temporal behaviors as far as their respective flux and spectral evolutions.

  18. Time resolved analysis of Fermi gamma-ray bursts with fast-and slow-cooled synchrotron photon models

    DOE PAGES

    Burgess, J. M.; Preece, R. D.; Connaughton, V.; ...

    2014-02-27

    Time-resolved spectroscopy is performed on eight bright, long gamma-ray bursts (GRBs) dominated by single emission pulses that were observed with the Fermi Gamma-Ray Space Telescope. Fitting the prompt radiation of GRBs by empirical spectral forms such as the Band function leads to ambiguous conclusions about the physical model for the prompt radiation. Moreover, the Band function is often inadequate to fit the data. Therefore, the GRB spectrum is modeled with two emission components consisting of optically thin non-thermal synchrotron radiation from relativistic electrons and, when significant, thermal emission from a jet photosphere, which is represented by a blackbody spectrum. Inmore » order to produce an acceptable fit, the addition of a blackbody component is required in five out of the eight cases. We also find that the low-energy spectral index α is consistent with a synchrotron component with α = –0.81 ± 0.1. This value lies between the limiting values of α = –2/3 and α = –3/2 for electrons in the slow- and fast-cooling regimes, respectively, suggesting ongoing acceleration at the emission site. The blackbody component can be more significant when using a physical synchrotron model instead of the Band function, illustrating that the Band function does not serve as a good proxy for a non-thermal synchrotron emission component. The temperature and characteristic emission-region size of the blackbody component are found to, respectively, decrease and increase as power laws with time during the prompt phase. Additionally, we find that the blackbody and non-thermal components have separate temporal behaviors as far as their respective flux and spectral evolutions.« less

  19. Time-resolved analysis of Fermi gamma-ray bursts with fast- and slow-cooled synchrotron photon models

    SciTech Connect

    Burgess, J. M.; Preece, R. D.; Connaughton, V.; Briggs, M. S.; Goldstein, A.; Bhat, P. N.; Paciesas, W. S.; Xiong, S.; Greiner, J.; Gruber, D.; Kienlin, A.; Rau, A.; Kouveliotou, C.; Meegan, C. A.; Axelsson, M.; Baring, M. G.; Dermer, C. D.; Iyyani, S.; Kocevski, D. E-mail: Rob.Preece@nasa.gov E-mail: baring@rice.edu; and others

    2014-03-20

    Time-resolved spectroscopy is performed on eight bright, long gamma-ray bursts (GRBs) dominated by single emission pulses that were observed with the Fermi Gamma-Ray Space Telescope. Fitting the prompt radiation of GRBs by empirical spectral forms such as the Band function leads to ambiguous conclusions about the physical model for the prompt radiation. Moreover, the Band function is often inadequate to fit the data. The GRB spectrum is therefore modeled with two emission components consisting of optically thin non-thermal synchrotron radiation from relativistic electrons and, when significant, thermal emission from a jet photosphere, which is represented by a blackbody spectrum. To produce an acceptable fit, the addition of a blackbody component is required in five out of the eight cases. We also find that the low-energy spectral index α is consistent with a synchrotron component with α = –0.81 ± 0.1. This value lies between the limiting values of α = –2/3 and α = –3/2 for electrons in the slow- and fast-cooling regimes, respectively, suggesting ongoing acceleration at the emission site. The blackbody component can be more significant when using a physical synchrotron model instead of the Band function, illustrating that the Band function does not serve as a good proxy for a non-thermal synchrotron emission component. The temperature and characteristic emission-region size of the blackbody component are found to, respectively, decrease and increase as power laws with time during the prompt phase. In addition, we find that the blackbody and non-thermal components have separate temporal behaviors as far as their respective flux and spectral evolutions.

  20. Time-Resolved Particle Image Velocimetry Measurements with Wall Shear Stress and Uncertainty Quantification for the FDA Nozzle Model.

    PubMed

    Raben, Jaime S; Hariharan, Prasanna; Robinson, Ronald; Malinauskas, Richard; Vlachos, Pavlos P

    2016-03-01

    We present advanced particle image velocimetry (PIV) processing, post-processing, and uncertainty estimation techniques to support the validation of computational fluid dynamics analyses of medical devices. This work is an extension of a previous FDA-sponsored multi-laboratory study, which used a medical device mimicking geometry referred to as the FDA benchmark nozzle model. Experimental measurements were performed using time-resolved PIV at five overlapping regions of the model for Reynolds numbers in the nozzle throat of 500, 2000, 5000, and 8000. Images included a twofold increase in spatial resolution in comparison to the previous study. Data was processed using ensemble correlation, dynamic range enhancement, and phase correlations to increase signal-to-noise ratios and measurement accuracy, and to resolve flow regions with large velocity ranges and gradients, which is typical of many blood-contacting medical devices. Parameters relevant to device safety, including shear stress at the wall and in bulk flow, were computed using radial basis functions. In addition, in-field spatially resolved pressure distributions, Reynolds stresses, and energy dissipation rates were computed from PIV measurements. Velocity measurement uncertainty was estimated directly from the PIV correlation plane, and uncertainty analysis for wall shear stress at each measurement location was performed using a Monte Carlo model. Local velocity uncertainty varied greatly and depended largely on local conditions such as particle seeding, velocity gradients, and particle displacements. Uncertainty in low velocity regions in the sudden expansion section of the nozzle was greatly reduced by over an order of magnitude when dynamic range enhancement was applied. Wall shear stress uncertainty was dominated by uncertainty contributions from velocity estimations, which were shown to account for 90-99% of the total uncertainty. This study provides advancements in the PIV processing methodologies over

  1. In vivo detection of macrophages in a rabbit atherosclerotic model by time-resolved laser-induced fluorescence spectroscopy

    PubMed Central

    Marcu, Laura; Fang, Qiyin; Jo, Javier A.; Papaioannou, Thanassis; Dorafshar, Amir; Reil, Todd; Qiao, Jian-Hua; Baker, J. Dennis; Freischlag, Julie A.; Fishbein, Michael C.

    2007-01-01

    Accumulation of numerous macrophages in the fibrous cap is a key identifying feature of plaque inflammation and vulnerability. This study investigates the use of time-resolved laser-induced fluorescence spectroscopy (TR-LIFS) as a potential tool for detection of macrophage foam cells in the intima of atherosclerotic plaques. Experiments were conducted in vivo on 14 New Zealand rabbits (6 control, 8 hypercholesterolemic) following aortotomy to expose the intimal luminal surface of the aorta. Tissue autofluorescence was induced with a nitrogen pulse laser (337 nm, 1 ns). Lesions were histologically classified by the percent of collagen or macrophage foam cells as well as thickness of the intima. Using parameters derived from the time-resolved fluorescence emission of plaques, we determined that intima rich in macrophage foam cells can be distinguished from intima rich in collagen with high sensitivity (>85%) and specificity (>95%). This study demonstrates, for the first time, that a time-resolved fluorescence-based technique can differentiate and demark macrophage content versus collagen content in vivo. Our results suggest that TR-LIFS technique can be used in clinical applications for identification of inflammatory cells important in plaque formation and rupture. PMID:16039283

  2. 3-dimensional modeling of transcranial magnetic stimulation: Design and application

    NASA Astrophysics Data System (ADS)

    Salinas, Felipe Santiago

    Over the past three decades, transcranial magnetic stimulation (TMS) has emerged as an effective tool for many research, diagnostic and therapeutic applications in humans. TMS delivers highly localized brain stimulations via non-invasive externally applied magnetic fields. This non-invasive, painless technique provides researchers and clinicians a unique tool capable of stimulating both the central and peripheral nervous systems. However, a complete analysis of the macroscopic electric fields produced by TMS has not yet been performed. In this dissertation, we present a thorough examination of the total electric field induced by TMS in air and a realistic head model with clinically relevant coil poses. In the first chapter, a detailed account of TMS coil wiring geometry was shown to provide significant improvements in the accuracy of primary E-field calculations. Three-dimensional models which accounted for the TMS coil's wire width, height, shape and number of turns clearly improved the fit of calculated-to-measured E-fields near the coil body. Detailed primary E-field models were accurate up to the surface of the coil body (within 0.5% of measured values) whereas simple models were often inadequate (up to 32% different from measured). In the second chapter, we addressed the importance of the secondary E-field created by surface charge accumulation during TMS using the boundary element method (BEM). 3-D models were developed using simple head geometries in order to test the model and compare it with measured values. The effects of tissue geometry, size and conductivity were also investigated. Finally, a realistic head model was used to assess the effect of multiple surfaces on the total E-field. We found that secondary E-fields have the greatest impact at areas in close proximity to each tissue layer. Throughout the head, the secondary E-field magnitudes were predominantly between 25% and 45% of the primary E-fields magnitude. The direction of the secondary E

  3. RCS calculations of 3-dimensional objects, modeled by CAD

    NASA Astrophysics Data System (ADS)

    Deleeneer, I.; Schweicher, E.; Barel, A.

    1991-09-01

    All the steps are detailed that one has to perform to enable efficient Radar Cross Section calculation for objects with a complex and general shape. Only cavities are supposed to be nonexistent at this state of the work. Before the actual RCS calculations, preliminary treatments like systematic modeling, Hidden Faces removal, and automatic recognition of reflection and diffraction centers are realized. After the creation of the object's geometry and its adaptation to the direction of the observator, Physical Optics (PO) was used to determine the backscattered field, and Geometrical Theory of Diffraction (GTD) was used to evaluate the diffracted fields. Only monostatic scattering (i.e., backscattering) is considered.

  4. 3-dimensional current collection model. [of Tethered Satellite System 1

    NASA Technical Reports Server (NTRS)

    Hwang, Kai-Shen; Shiah, A.; Wu, S. T.; Stone, N.

    1992-01-01

    A three-dimensional, time dependent current collection model of a satellite has been developed for the TSS-1 system. The system has been simulated particularly for the Research of Plasma Electrodynamics (ROPE) experiment. The Maxwellian distributed particles with the geomagnetic field effects are applied in this numerical simulation. The preliminary results indicate that a ring current is observed surrounding the satellite in the equatorial plane. This ring current is found between the plasma sheath and the satellite surface and is oscillating with a time scale of approximately 1 microsec. This is equivalent to the electron plasma frequency. An hour glass shape of electron distribution was observed when the viewing direction is perpendicular to the equatorial plane. This result is consistent with previous findings from Linson (1969) and Antoniades et al. (1990). Electrons that are absorbed by the satellite are limited from the background ionosphere as indicated by Parker and Murphy (1967).

  5. Simple parameter estimation for complex models — Testing evolutionary techniques on 3-dimensional biogeochemical ocean models

    NASA Astrophysics Data System (ADS)

    Mattern, Jann Paul; Edwards, Christopher A.

    2017-01-01

    Parameter estimation is an important part of numerical modeling and often required when a coupled physical-biogeochemical ocean model is first deployed. However, 3-dimensional ocean model simulations are computationally expensive and models typically contain upwards of 10 parameters suitable for estimation. Hence, manual parameter tuning can be lengthy and cumbersome. Here, we present four easy to implement and flexible parameter estimation techniques and apply them to two 3-dimensional biogeochemical models of different complexities. Based on a Monte Carlo experiment, we first develop a cost function measuring the model-observation misfit based on multiple data types. The parameter estimation techniques are then applied and yield a substantial cost reduction over ∼ 100 simulations. Based on the outcome of multiple replicate experiments, they perform on average better than random, uninformed parameter search but performance declines when more than 40 parameters are estimated together. Our results emphasize the complex cost function structure for biogeochemical parameters and highlight dependencies between different parameters as well as different cost function formulations.

  6. 3-dimensional orthodontics visualization system with dental study models and orthopantomograms

    NASA Astrophysics Data System (ADS)

    Zhang, Hua; Ong, S. H.; Foong, K. W. C.; Dhar, T.

    2005-04-01

    The aim of this study is to develop a system that provides 3-dimensional visualization of orthodontic treatments. Dental plaster models and corresponding orthopantomogram (dental panoramic tomogram) are first digitized and fed into the system. A semi-auto segmentation technique is applied to the plaster models to detect the dental arches, tooth interstices and gum margins, which are used to extract individual crown models. 3-dimensional representation of roots, generated by deforming generic tooth models with orthopantomogram using radial basis functions, is attached to corresponding crowns to enable visualization of complete teeth. An optional algorithm to close the gaps between deformed roots and actual crowns by using multi-quadratic radial basis functions is also presented, which is capable of generating smooth mesh representation of complete 3-dimensional teeth. User interface is carefully designed to achieve a flexible system with as much user friendliness as possible. Manual calibration and correction is possible throughout the data processing steps to compensate occasional misbehaviors of automatic procedures. By allowing the users to move and re-arrange individual teeth (with their roots) on a full dentition, this orthodontic visualization system provides an easy and accurate way of simulation and planning of orthodontic treatment. Its capability of presenting 3-dimensional root information with only study models and orthopantomogram is especially useful for patients who do not undergo CT scanning, which is not a routine procedure in most orthodontic cases.

  7. Exciton transfer between localized states in CdS1- xSex alloys: Time-resolved photoluminescence and theoretical models

    NASA Astrophysics Data System (ADS)

    Gourdon, C.; Lavallard, P.

    1990-04-01

    Luminescence decay curves as well as time-resolved and time-integrated spectra obtained with selective excitation in the localized exciton band of CdS1- xSex are fitted using two theoretical models. In the first one, exciton transfer to lower energy states occurs through tunnel effect assisted by acoustical phonons. From the energy dependence of the lifetime measured with quasi-resonant excitation in the localized exciton band, we determine the characteristic energy of the tail density of states: E0 = 2.2 meV. The radiative lifetime is set equal to 1.5 ns. We show that both piezoelectric and deformation potential coupling have to be taken into account to describe exciton transfer. The second model is phenomenological and was used to describe exciton transfer in GaAs1- xPx alloys. We obtain a good agreement with experimental results using parameters close to the previous ones. We demonstrate that, for selective excitation in the low energy side of the luminescence band, not only the transfer process but also luminescence assisted by acoustical phonons must be taken into account in order to explain time-resolved luminescence results.

  8. Time-resolved transillumination and optical tomography

    NASA Astrophysics Data System (ADS)

    de Haller, Emmanuel B.

    1996-01-01

    In response to an invitation by the editor-in-chief, I would like to present the current status of time-domain imaging. With exciting new photon diffusion techniques being developed in the frequency domain and promising optical coherence tomography, time-resolved transillumination is in constant evolution and the subject of passionate discussions during the numerous conferences dedicated to this subject. The purpose of time-resolved optical tomography is to provide noninvasive, high-resolution imaging of the interior of living bodies by the use of nonionizing radiation. Moreover, the use of visible to near-infrared wavelength yields metabolic information. Breast cancer screening is the primary potential application for time-resolved imaging. Neurology and tissue characterization are also possible fields of applications. Time- resolved transillumination and optical tomography should not only improve diagnoses, but the welfare of the patient. As no overview of this technique has yet been presented to my knowledge, this paper briefly describes the various methods enabling time-resolved transillumination and optical tomography. The advantages and disadvantages of these methods, as well as the clinical challenges they face are discussed. Although an analytic and computable model of light transport through tissues is essential for a meaningful interpretation of the transillumination process, this paper will not dwell on the mathematics of photon propagation.

  9. Spectroscopic studies of model photo-receptors: validation of a nanosecond time-resolved micro-spectrophotometer design using photoactive yellow protein and α-phycoerythrocyanin.

    PubMed

    Purwar, Namrta; Tenboer, Jason; Tripathi, Shailesh; Schmidt, Marius

    2013-09-13

    Time-resolved spectroscopic experiments have been performed with protein in solution and in crystalline form using a newly designed microspectrophotometer. The time-resolution of these experiments can be as good as two nanoseconds (ns), which is the minimal response time of the image intensifier used. With the current setup, the effective time-resolution is about seven ns, determined mainly by the pulse duration of the nanosecond laser. The amount of protein required is small, on the order of 100 nanograms. Bleaching, which is an undesirable effect common to photoreceptor proteins, is minimized by using a millisecond shutter to avoid extensive exposure to the probing light. We investigate two model photoreceptors, photoactive yellow protein (PYP), and α-phycoerythrocyanin (α-PEC), on different time scales and at different temperatures. Relaxation times obtained from kinetic time-series of difference absorption spectra collected from PYP are consistent with previous results. The comparison with these results validates the capability of this spectrophotometer to deliver high quality time-resolved absorption spectra.

  10. Spectroscopic Studies of Model Photo-Receptors: Validation of a Nanosecond Time-Resolved Micro-Spectrophotometer Design Using Photoactive Yellow Protein and α-Phycoerythrocyanin

    PubMed Central

    Purwar, Namrta; Tenboer, Jason; Tripathi, Shailesh; Schmidt, Marius

    2013-01-01

    Time-resolved spectroscopic experiments have been performed with protein in solution and in crystalline form using a newly designed microspectrophotometer. The time-resolution of these experiments can be as good as two nanoseconds (ns), which is the minimal response time of the image intensifier used. With the current setup, the effective time-resolution is about seven ns, determined mainly by the pulse duration of the nanosecond laser. The amount of protein required is small, on the order of 100 nanograms. Bleaching, which is an undesirable effect common to photoreceptor proteins, is minimized by using a millisecond shutter to avoid extensive exposure to the probing light. We investigate two model photoreceptors, photoactive yellow protein (PYP), and α-phycoerythrocyanin (α-PEC), on different time scales and at different temperatures. Relaxation times obtained from kinetic time-series of difference absorption spectra collected from PYP are consistent with previous results. The comparison with these results validates the capability of this spectrophotometer to deliver high quality time-resolved absorption spectra. PMID:24065094

  11. Time-resolved spectroscopy at surfaces and adsorbate dynamics:insights from a model-system approach

    NASA Astrophysics Data System (ADS)

    Boström, Emil; Mikkelsen, Anders; Verdozzi, Claudio

    We introduce a finite-system, model description of the initial stages of femtosecond laser induced desorption at surfaces. Using the exact many-body time evolution and also results from a novel time-dependent DFT description for electron-nuclear systems, we analyse the competition between several surface-response mechanisms and electronic correlations in the transient and longer time dynamics under the influence of dipole-coupled fields. Our model allows us to explore how coherent multiple-pulse protocols impact desorption in a variety of prototypical experiments.

  12. Time-resolved vibrational spectroscopy

    SciTech Connect

    Tokmakoff, Andrei; Champion, Paul; Heilweil, Edwin J.; Nelson, Keith A.; Ziegler, Larry

    2009-05-14

    This document contains the Proceedings from the 14th International Conference on Time-Resolved Vibrational Spectroscopy, which was held in Meredith, NH from May 9-14, 2009. The study of molecular dynamics in chemical reaction and biological processes using time-resolved spectroscopy plays an important role in our understanding of energy conversion, storage, and utilization problems. Fundamental studies of chemical reactivity, molecular rearrangements, and charge transport are broadly supported by the DOE's Office of Science because of their role in the development of alternative energy sources, the understanding of biological energy conversion processes, the efficient utilization of existing energy resources, and the mitigation of reactive intermediates in radiation chemistry. In addition, time-resolved spectroscopy is central to all fiveof DOE's grand challenges for fundamental energy science. The Time-Resolved Vibrational Spectroscopy conference is organized biennially to bring the leaders in this field from around the globe together with young scientists to discuss the most recent scientific and technological advances. The latest technology in ultrafast infrared, Raman, and terahertz spectroscopy and the scientific advances that these methods enable were covered. Particular emphasis was placed on new experimental methods used to probe molecular dynamics in liquids, solids, interfaces, nanostructured materials, and biomolecules.

  13. Investigations on the Interactions of 5-Fluorouracil with Herring Sperm DNA: Steady State/Time Resolved and Molecular Modeling Studies

    NASA Astrophysics Data System (ADS)

    Chinnathambi, Shanmugavel; Karthikeyan, Subramani; Velmurugan, Devadasan; Hanagata, Nobutaka; Aruna, Prakasarao; Ganesan, Singaravelu

    2015-04-01

    In the present study, the interaction of 5-Fluorouracil with herring sperm DNA is reported using spectroscopic and molecular modeling techniques. This binding study of 5-FU with hs-DNA is of paramount importance in understanding chemico-biological interactions for drug design, pharmacy and biochemistry without altering the original structure. The challenge of the study was to find the exact binding mode of the drug 5-Fluorouracil with hs-DNA. From the absorption studies, a hyperchromic effect was observed for the herring sperm DNA in the presence of 5-Fluorouracil and a binding constant of 6.153 × 103 M-1 for 5-Fluorouracil reveals the existence of weak interaction between the 5-Fluorouracil and herring sperm DNA. Ethidium bromide loaded herring sperm DNA showed a quenching in the fluorescence intensity after the addition of 5-Fluorouracil. The binding constants for 5-Fluorouracil stranded DNA and competitive bindings of 5-FU interacting with DNA-EB systems were examined by fluorescence spectra. The Stern-Volmer plots and fluorescence lifetime results confirm the static quenching nature of the drug-DNA complex. The binding constant Kb was 2.5 × 104 L mol-1 and the number of binding sites are 1.17. The 5-FU on DNA system was calculated using double logarithmic plot. From the Forster nonradiative energy transfer study it has been found that the distance of 5-FU from DNA was 4.24 nm. In addition to the spectroscopic results, the molecular modeling studies also revealed the major groove binding as well as the partial intercalation mode of binding between the 5-Fluorouracil and herring sperm DNA. The binding energy and major groove binding as -6.04 kcal mol-1 and -6.31 kcal mol-1 were calculated from the modeling studies. All the testimonies manifested that binding modes between 5-Fluorouracil and DNA were evidenced to be groove binding and in partial intercalative mode.

  14. The CO oxidation kinetics on supported Pd model catalysts: A molecular beam/in situ time-resolved infrared reflection absorption spectroscopy study

    NASA Astrophysics Data System (ADS)

    Libuda, J.; Meusel, I.; Hoffmann, J.; Hartmann, J.; Piccolo, L.; Henry, C. R.; Freund, H.-J.

    2001-03-01

    Combining molecular beam techniques and time-resolved infrared reflection absorption spectroscopy (TR-IRAS) we have studied the kinetics of the CO oxidation reaction on an alumina-supported Pd model catalyst. The Pd particles are deposited by metal evaporation under ultrahigh vacuum (UHV) conditions onto a well-ordered alumina film, prepared on a NiAl(110) single crystal. Particle size, density and structure of the Pd deposits have been characterized in previous studies. In the low temperature region, transient and steady-state experiments have been performed over a wide range of CO and oxygen fluxes by crossing two effusive molecular beams on the sample surface. We determine the steady-state CO2 production rate as a function of the CO fraction in the impinging gas flux. Simultaneously, the occupation of CO adsorption sites under steady-state conditions is monitored by in situ IR spectroscopy. The origin of different types of CO2 transients is discussed. In particular we focus on the transient CO2 production after switching off the CO beam. For the model catalyst investigated, detailed reaction rate measurements in combination with time-resolved IRAS show that the origin of the particular transient behavior of the supported model system is not due to the presence of specific adsorption sites on small particles, as has been proposed previously. Instead, we show that the transient behavior can be semiquantitatively simulated on the basis of a simple kinetic model considering a homogeneous surface, and accounting for the inhibition of the dissociative adsorption of O2 at high CO coverage. Moreover, it is discussed how the inherent heterogeneity of the supported particle system can additionally enhance the observed effect.

  15. A novel model on time-resolved photoluminescence measurements of polar InGaN/GaN multi-quantum-well structures

    PubMed Central

    Xing, Yuchen; Wang, Lai; Yang, Di; Wang, Zilan; Hao, Zhibiao; Sun, Changzheng; Xiong, Bing; Luo, Yi; Han, Yanjun; Wang, Jian; Li, Hongtao

    2017-01-01

    Based on carrier rate equation, a new model is proposed to explain the non-exponential nature of time-resolved photoluminescence (TRPL) decay curves in the polar InGaN/GaN multi-quantum-well structures. From the study of TRPL curves at different temperatures, it is found that both radiative and non-radiative recombination coefficients vary from low temperature to room temperature. The variation of the coefficients is compatible with the carrier density of states distribution as well as the carrier localization process. These results suggest that there is a novel method to calculate the internal quantum efficiency, which is a complement to the traditional one based on temperature dependent photoluminescence measurement. PMID:28327629

  16. A novel model on time-resolved photoluminescence measurements of polar InGaN/GaN multi-quantum-well structures

    NASA Astrophysics Data System (ADS)

    Xing, Yuchen; Wang, Lai; Yang, Di; Wang, Zilan; Hao, Zhibiao; Sun, Changzheng; Xiong, Bing; Luo, Yi; Han, Yanjun; Wang, Jian; Li, Hongtao

    2017-03-01

    Based on carrier rate equation, a new model is proposed to explain the non-exponential nature of time-resolved photoluminescence (TRPL) decay curves in the polar InGaN/GaN multi-quantum-well structures. From the study of TRPL curves at different temperatures, it is found that both radiative and non-radiative recombination coefficients vary from low temperature to room temperature. The variation of the coefficients is compatible with the carrier density of states distribution as well as the carrier localization process. These results suggest that there is a novel method to calculate the internal quantum efficiency, which is a complement to the traditional one based on temperature dependent photoluminescence measurement.

  17. A novel model on time-resolved photoluminescence measurements of polar InGaN/GaN multi-quantum-well structures.

    PubMed

    Xing, Yuchen; Wang, Lai; Yang, Di; Wang, Zilan; Hao, Zhibiao; Sun, Changzheng; Xiong, Bing; Luo, Yi; Han, Yanjun; Wang, Jian; Li, Hongtao

    2017-03-22

    Based on carrier rate equation, a new model is proposed to explain the non-exponential nature of time-resolved photoluminescence (TRPL) decay curves in the polar InGaN/GaN multi-quantum-well structures. From the study of TRPL curves at different temperatures, it is found that both radiative and non-radiative recombination coefficients vary from low temperature to room temperature. The variation of the coefficients is compatible with the carrier density of states distribution as well as the carrier localization process. These results suggest that there is a novel method to calculate the internal quantum efficiency, which is a complement to the traditional one based on temperature dependent photoluminescence measurement.

  18. Time-Resolved Transcriptomics and Constraint-Based Modeling Identify System-Level Metabolic Features and Overexpression Targets to Increase Spiramycin Production in Streptomyces ambofaciens

    PubMed Central

    Fondi, Marco; Pinatel, Eva; Talà, Adelfia; Damiano, Fabrizio; Consolandi, Clarissa; Mattorre, Benedetta; Fico, Daniela; Testini, Mariangela; De Benedetto, Giuseppe E.; Siculella, Luisa; De Bellis, Gianluca; Alifano, Pietro; Peano, Clelia

    2017-01-01

    In this study we have applied an integrated system biology approach to characterize the metabolic landscape of Streptomyces ambofaciens and to identify a list of potential metabolic engineering targets for the overproduction of the secondary metabolites in this microorganism. We focused on an often overlooked growth period (i.e., post-first rapid growth phase) and, by integrating constraint-based metabolic modeling with time resolved RNA-seq data, we depicted the main effects of changes in gene expression on the overall metabolic reprogramming occurring in S. ambofaciens. Moreover, through metabolic modeling, we unraveled a set of candidate overexpression gene targets hypothetically leading to spiramycin overproduction. Model predictions were experimentally validated by genetic manipulation of the recently described ethylmalonyl-CoA metabolic node, providing evidence that spiramycin productivity may be increased by enhancing the carbon flow through this pathway. The goal was achieved by over-expressing the ccr paralog srm4 in an ad hoc engineered plasmid. This work embeds the first metabolic reconstruction of S. ambofaciens and the successful experimental validation of model predictions and demonstrates the validity and the importance of in silico modeling tools for the overproduction of molecules with a biotechnological interest. Finally, the proposed metabolic reconstruction, which includes manually refined pathways for several secondary metabolites with antimicrobial activity, represents a solid platform for the future exploitation of S. ambofaciens biotechnological potential. PMID:28553270

  19. Time-Resolved Transcriptomics and Constraint-Based Modeling Identify System-Level Metabolic Features and Overexpression Targets to Increase Spiramycin Production in Streptomyces ambofaciens.

    PubMed

    Fondi, Marco; Pinatel, Eva; Talà, Adelfia; Damiano, Fabrizio; Consolandi, Clarissa; Mattorre, Benedetta; Fico, Daniela; Testini, Mariangela; De Benedetto, Giuseppe E; Siculella, Luisa; De Bellis, Gianluca; Alifano, Pietro; Peano, Clelia

    2017-01-01

    In this study we have applied an integrated system biology approach to characterize the metabolic landscape of Streptomyces ambofaciens and to identify a list of potential metabolic engineering targets for the overproduction of the secondary metabolites in this microorganism. We focused on an often overlooked growth period (i.e., post-first rapid growth phase) and, by integrating constraint-based metabolic modeling with time resolved RNA-seq data, we depicted the main effects of changes in gene expression on the overall metabolic reprogramming occurring in S. ambofaciens. Moreover, through metabolic modeling, we unraveled a set of candidate overexpression gene targets hypothetically leading to spiramycin overproduction. Model predictions were experimentally validated by genetic manipulation of the recently described ethylmalonyl-CoA metabolic node, providing evidence that spiramycin productivity may be increased by enhancing the carbon flow through this pathway. The goal was achieved by over-expressing the ccr paralog srm4 in an ad hoc engineered plasmid. This work embeds the first metabolic reconstruction of S. ambofaciens and the successful experimental validation of model predictions and demonstrates the validity and the importance of in silico modeling tools for the overproduction of molecules with a biotechnological interest. Finally, the proposed metabolic reconstruction, which includes manually refined pathways for several secondary metabolites with antimicrobial activity, represents a solid platform for the future exploitation of S. ambofaciens biotechnological potential.

  20. A 3-dimensional model for teaching local flaps using porcine skin.

    PubMed

    Hassan, Zahid; Hogg, Fiona; Graham, Ken

    2014-10-01

    The European Working Time Directive and streamlined training has led to reduced training time. Surgery, as an experience-dependent craft specialty is affected more than other medical specialties. Trainees want to maximize all training opportunities in the clinical setting, and having predeveloped basic skills acquired on a simulated model can facilitate this.Here we describe the use of a novel model to design and raise local flaps in the face and scalp regions. The model consists of mannequin heads draped with porcine skin which is skewered with pins at strategic points to give a 3-dimensional model which closely resembles a cadaveric head.The advantages of this model are that it is life size and incorporates all the relevant anatomical features, which can be drawn on if required.This model was used on a recent course, Intermediate Skills in Plastic Surgery: Flaps Around the Face, at the Royal College of Surgeons England. The trainees found that practicing on the porcine skin gave them an opportunity to master the basics of flap design and implementation.In summary, this innovative 3-dimensional training model has received high levels of satisfaction and is currently as close as we can get to cadaveric dissection without the constraints and cost of using human tissue.

  1. Finite-difference time-domain analysis of time-resolved reflectance from an adult head model composed of multilayered slabs with a nonscattering layer.

    PubMed

    Tanifuji, Tadatoshi; Nishio, Naoya; Okimatsu, Kazuya; Tabata, Shougo; Hashimoto, Yasunari

    2012-02-01

    Finite-difference time-domain (FDTD) analysis has been used to predict the time-resolved reflectance from multilayered slabs with a nonscattering layer. Light propagation across the nonscattering layer was calculated based on the light intensity characteristics along a ray in free space. Additional equivalent source functions due to light from scattering regions across the nonscattering region were introduced into the diffusion equation and an additional set of the diffusion equation was solved by FDTD analysis by employing new boundary conditions. The formulation was used to calculate time-resolved reflectances of three- and four-layered slabs containing a nonscattering layer. The received light intensity and the mean time of flight estimated from the time-resolved reflectance are in reasonable agreement with previously reported experimental data and Monte Carlo simulations.

  2. Optimized time-resolved imaging of contrast kinetics (TRICKS) in dynamic contrast-enhanced MRI after peptide receptor radionuclide therapy in small animal tumor models.

    PubMed

    Haeck, Joost; Bol, Karin; Bison, Sander; van Tiel, Sandra; Koelewijn, Stuart; de Jong, Marion; Veenland, Jifke; Bernsen, Monique

    2015-01-01

    Anti-tumor efficacy of targeted peptide-receptor radionuclide therapy (PRRT) relies on several factors, including functional tumor vasculature. Little is known about the effect of PRRT on tumor vasculature. With dynamic contrast-enhanced (DCE-) MRI, functional vasculature is imaged and quantified using contrast agents. In small animals DCE-MRI is a challenging application. We optimized a clinical sequence for fast hemodynamic acquisitions, time-resolved imaging of contrast kinetics (TRICKS), to obtain DCE-MRI images at both high spatial and high temporal resolution in mice and rats. Using TRICKS, functional vasculature was measured prior to PRRT and longitudinally to investigate the effect of treatment on tumor vascular characteristics. Nude mice bearing H69 tumor xenografts and rats bearing syngeneic CA20948 tumors were used to study perfusion following PRRT administration with (177) lutetium octreotate. Both semi-quantitative and quantitative parameters were calculated. Treatment efficacy was measured by tumor-size reduction. Optimized TRICKS enabled MRI at 0.032 mm(3) voxel size with a temporal resolution of less than 5 s and large volume coverage, a substantial improvement over routine pre-clinical DCE-MRI studies. Tumor response to therapy was reflected in changes in tumor perfusion/permeability parameters. The H69 tumor model showed pronounced changes in DCE-derived parameters following PRRT. The rat CA20948 tumor model showed more heterogeneity in both treatment outcome and perfusion parameters. TRICKS enabled the acquisition of DCE-MRI at both high temporal resolution (Tres ) and spatial resolutions relevant for small animal tumor models. With the high Tres enabled by TRICKS, accurate pharmacokinetic data modeling was feasible. DCE-MRI parameters revealed changes over time and showed a clear relationship between tumor size and Ktrans .

  3. High resolution 3-Dimensional imaging of the human cardiac conduction system from microanatomy to mathematical modeling.

    PubMed

    Stephenson, Robert S; Atkinson, Andrew; Kottas, Petros; Perde, Filip; Jafarzadeh, Fatemeh; Bateman, Mike; Iaizzo, Paul A; Zhao, Jichao; Zhang, Henggui; Anderson, Robert H; Jarvis, Jonathan C; Dobrzynski, Halina

    2017-08-03

    Cardiac arrhythmias and conduction disturbances are accompanied by structural remodelling of the specialised cardiomyocytes known collectively as the cardiac conduction system. Here, using contrast enhanced micro-computed tomography, we present, in attitudinally appropriate fashion, the first 3-dimensional representations of the cardiac conduction system within the intact human heart. We show that cardiomyocyte orientation can be extracted from these datasets at spatial resolutions approaching the single cell. These data show that commonly accepted anatomical representations are oversimplified. We have incorporated the high-resolution anatomical data into mathematical simulations of cardiac electrical depolarisation. The data presented should have multidisciplinary impact. Since the rate of depolarisation is dictated by cardiac microstructure, and the precise orientation of the cardiomyocytes, our data should improve the fidelity of mathematical models. By showing the precise 3-dimensional relationships between the cardiac conduction system and surrounding structures, we provide new insights relevant to valvar replacement surgery and ablation therapies. We also offer a practical method for investigation of remodelling in disease, and thus, virtual pathology and archiving. Such data presented as 3D images or 3D printed models, will inform discussions between medical teams and their patients, and aid the education of medical and surgical trainees.

  4. Use of 3-Dimensional Printing to Create Patient-Specific Thoracic Spine Models as Task Trainers.

    PubMed

    Jeganathan, Jelliffe; Baribeau, Yanick; Bortman, Jeffrey; Mahmood, Feroze; Shnider, Marc; Ahmed, Muneeb; Mashari, Azad; Amir, Rabia; Amador, Yannis; Matyal, Robina

    Thoracic epidural anesthesia is a technically challenging procedure with a high failure rate of 24% to 32% nationwide. Residents in anesthesiology have limited opportunities to practice this technique adequately, and there are no training tools available for this purpose. Our objective was to build a low-cost patient-specific thoracic epidural training model. We obtained thoracic computed tomography scan data from patients with normal and kyphotic spine. The thoracic spine was segmented from the scan, and a 3-dimensional model of the spine was generated and printed. It was then placed in a customized wooden box and filled with different types of silicone to mimic human tissues. Attending physicians in our institution then tested the final model. They were asked to fill out a brief questionnaire after the identification of the landmarks and epidural space using ultrasound and real-time performance for a thoracic epidural on the model (Supplemental Digital Content 1, http://links.lww.com/AAP/A197). Likert scoring system was used for scoring. The time to develop this simulator model took less than 4 days, and the materials cost approximately $400. Fourteen physicians tested the model for determining the realistic sensation while palpating the spinous process, needle entry through the silicone, the "pop" sensation and ultrasound fidelity of the model. Whereas the tactile fidelity scores were "neutral" (3.08, 3.06, and 3.0, respectively), the ultrasound guidance and overall suitability for residents were highly rated as being the most realistic (4.85 and 4.0, respectively). It is possible to develop homemade, low-cost, patient-specific, and high-fidelity ultrasound guidance simulators for resident training in thoracic epidurals using 3-dimensional printing technology.

  5. Argon metastables in HiPIMS: validation of the ionization region model by direct comparison to time resolved tunable diode-laser diagnostics

    NASA Astrophysics Data System (ADS)

    Stancu, G. D.; Brenning, N.; Vitelaru, C.; Lundin, D.; Minea, T.

    2015-08-01

    The volume plasma interactions of high power impulse magnetron sputtering (HiPIMS) discharges operated with a Ti target is analyzed in detail by combining time-resolved diagnostics with modeling of plasma kinetics. The model employed is the ionization region model (IRM) with an improved and detailed treatment of the kinetics of the argon metastable (Arm) state, called m-IRM. The diagnostics used is tunable diode-laser absorption spectroscopy (TD-LAS) of the Arm state, which gives the line-of-sight density integrated along the laser path parallel to the target surface. The TD-LAS recordings exhibit quite complex temporal evolutions Arm(t), with distinct features that are shown to reflect the time evolution of the plasma (the electron density and temperature), and of the argon gas (gas rarefaction and refill). The Arm(t) function is thus a tracer for the most important aspects of internal discharge physics, and therefore suitable for model testing and validation. The IRM model is constructed to be locked to obey specific experimental macroscopic discharge parameters, specifically the discharge current ID(t) and the voltage UD(t). It has to this purpose been run with the appropriate process gas pressures (from 0.67 to 2.67 Pa), with the experimentally applied voltage pulse profiles UD(t), and with the resulting current pulse profiles ID(t) (with maxima from 0.5 to 70 A). It is shown that the model reproduces the features in the TD-LAS measurements: both the Arm(t) evolution in single pulses, and how the pulse shapes change with gas pressure and with pulse amplitude. The good agreement between the measurements and model output is in this work taken to validate the basic assumptions of the m-IRM. In addition, the m-IRM results have been used to unravel the connections between volume plasma kinetics and various features recorded in the TD-LAS measurement, and to generalize the foremost characteristics of the studied discharges.

  6. Using 3-dimensional printing to create presurgical models for endodontic surgery.

    PubMed

    Bahcall, James K

    2014-09-01

    Advances in endodontic surgery--from both a technological and procedural perspective-have been significant over the last 18 years. Although these technologies and procedural enhancements have significantly improved endodontic surgical treatment outcomes, there is still an ongoing challenge of overcoming the limitations of interpreting preoperative 2-dimensional (2-D) radiographic representation of a 3-dimensional (3-D) in vivo surgical field. Cone-beam Computed Tomography (CBCT) has helped to address this issue by providing a 3-D enhancement of the 2-D radiograph. The next logical step to further improve a presurgical case 3-D assessment is to create a surgical model from the CBCT scan. The purpose of this article is to introduce 3-D printing of CBCT scans for creating presurgical models for endodontic surgery.

  7. Time- and frequency-dependent model of time-resolved coherent anti-Stokes Raman scattering (CARS) with a picosecond-duration probe pulse

    NASA Astrophysics Data System (ADS)

    Stauffer, Hans U.; Miller, Joseph D.; Slipchenko, Mikhail N.; Meyer, Terrence R.; Prince, Benjamin D.; Roy, Sukesh; Gord, James R.

    2014-01-01

    The hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps CARS) technique presents a promising alternative to either fs time-resolved or ps frequency-resolved CARS in both gas-phase thermometry and condensed-phase excited-state dynamics applications. A theoretical description of time-dependent CARS is used to examine this recently developed probe technique, and quantitative comparisons of the full time-frequency evolution show excellent accuracy in predicting the experimental vibrational CARS spectra obtained for two model systems. The interrelated time- and frequency-domain spectral signatures of gas-phase species produced by hybrid fs/ps CARS are explored with a focus on gas-phase N2 vibrational CARS, which is commonly used as a thermometric diagnostic of combusting flows. In particular, we discuss the merits of the simple top-hat spectral filter typically used to generate the ps-duration hybrid fs/ps CARS probe pulse, including strong discrimination against non-resonant background that often contaminates CARS signal. It is further demonstrated, via comparison with vibrational CARS results on a time-evolving solvated organic chromophore, that this top-hat probe-pulse configuration can provide improved spectral resolution, although the degree of improvement depends on the dephasing timescales of the observed molecular modes and the duration and timing of the narrowband final pulse. Additionally, we discuss the virtues of a frequency-domain Lorentzian probe-pulse lineshape and its potential for improving the hybrid fs/ps CARS technique as a diagnostic in high-pressure gas-phase thermometry applications.

  8. Time- and frequency-dependent model of time-resolved coherent anti-Stokes Raman scattering (CARS) with a picosecond-duration probe pulse.

    PubMed

    Stauffer, Hans U; Miller, Joseph D; Slipchenko, Mikhail N; Meyer, Terrence R; Prince, Benjamin D; Roy, Sukesh; Gord, James R

    2014-01-14

    The hybrid femtosecond∕picosecond coherent anti-Stokes Raman scattering (fs∕ps CARS) technique presents a promising alternative to either fs time-resolved or ps frequency-resolved CARS in both gas-phase thermometry and condensed-phase excited-state dynamics applications. A theoretical description of time-dependent CARS is used to examine this recently developed probe technique, and quantitative comparisons of the full time-frequency evolution show excellent accuracy in predicting the experimental vibrational CARS spectra obtained for two model systems. The interrelated time- and frequency-domain spectral signatures of gas-phase species produced by hybrid fs∕ps CARS are explored with a focus on gas-phase N2 vibrational CARS, which is commonly used as a thermometric diagnostic of combusting flows. In particular, we discuss the merits of the simple top-hat spectral filter typically used to generate the ps-duration hybrid fs∕ps CARS probe pulse, including strong discrimination against non-resonant background that often contaminates CARS signal. It is further demonstrated, via comparison with vibrational CARS results on a time-evolving solvated organic chromophore, that this top-hat probe-pulse configuration can provide improved spectral resolution, although the degree of improvement depends on the dephasing timescales of the observed molecular modes and the duration and timing of the narrowband final pulse. Additionally, we discuss the virtues of a frequency-domain Lorentzian probe-pulse lineshape and its potential for improving the hybrid fs∕ps CARS technique as a diagnostic in high-pressure gas-phase thermometry applications.

  9. Accuracy of 3-dimensional curvilinear measurements on digital models with intraoral scanners.

    PubMed

    Mack, Spencer; Bonilla, Tammy; English, Jeryl D; Cozad, Benjamin; Akyalcin, Sercan

    2017-09-01

    Our objectives were to evaluate and compare the digital dental models generated from 2 commercial intraoral scanners with manual measurements when performing 3-dimensional surface measurements along a curved line (curvilinear). Dry mandibles (n = 61) with intact dentition were used. The mandibles were digitized using 2 chair-side intraoral scanners: Cadent iTero (Align Technology, San Jose, Calif) and Lythos Digital Impression system (Ormco, Orange, Calif). Digitized 3-dimensional models were converted to individual stereolithography files and used with commercial software to obtain the curvilinear measurements. Manual measurements were carried out directly on the mandibular teeth. Measurements were made on different locations on the dental arch in various directions. One-sample t tests and linear regression analyses were performed. To further graphically examine the accuracy between the different methods, Bland-Altman plots were computed. The level of significance was set at P <0.05. There were no significant differences between any of the paired methods; this indicated a certain level of agreement between the methods tested (P >0.05). Bland-Altman analysis showed no fixed bias of 1 approach vs the other, and random errors were detected in all comparisons. Although the mean biases of the digital models obtained by the iTero and Lythos scanners, when compared with direct caliper measurements, were low, the comparison of the 2 intraoral scanners yielded the lowest mean bias. No comparison displayed statistical significance for the t scores; this indicated the absence of proportional bias in these comparisons. The intraoral scanners tested in this study produced digital dental models that were comparatively accurate when performing direct surface measurements along a curved line in 3 dimensions. Copyright © 2017 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

  10. 3-Dimensional Geologic Modeling Applied to the Structural Characterization of Geothermal Systems: Astor Pass, Nevada, USA

    SciTech Connect

    Siler, Drew L; Faulds, James E; Mayhew, Brett

    2013-04-16

    Geothermal systems in the Great Basin, USA, are controlled by a variety of fault intersection and fault interaction areas. Understanding the specific geometry of the structures most conducive to broad-scale geothermal circulation is crucial to both the mitigation of the costs of geothermal exploration (especially drilling) and to the identification of geothermal systems that have no surface expression (blind systems). 3-dimensional geologic modeling is a tool that can elucidate the specific stratigraphic intervals and structural geometries that host geothermal reservoirs. Astor Pass, NV USA lies just beyond the northern extent of the dextral Pyramid Lake fault zone near the boundary between two distinct structural domains, the Walker Lane and the Basin and Range, and exhibits characteristics of each setting. Both northwest-striking, left-stepping dextral faults of the Walker Lane and kinematically linked northerly striking normal faults associated with the Basin and Range are present. Previous studies at Astor Pass identified a blind geothermal system controlled by the intersection of west-northwest and north-northwest striking dextral-normal faults. Wells drilled into the southwestern quadrant of the fault intersection yielded 94°C fluids, with geothermometers suggesting a maximum reservoir temperature of 130°C. A 3-dimensional model was constructed based on detailed geologic maps and cross-sections, 2-dimensional seismic data, and petrologic analysis of the cuttings from three wells in order to further constrain the structural setting. The model reveals the specific geometry of the fault interaction area at a level of detail beyond what geologic maps and cross-sections can provide.

  11. Virtual electrophysiological study in a 3-dimensional cardiac magnetic resonance imaging model of porcine myocardial infarction.

    PubMed

    Ng, Jason; Jacobson, Jason T; Ng, Justin K; Gordon, David; Lee, Daniel C; Carr, James C; Goldberger, Jeffrey J

    2012-07-31

    This study sought to test the hypothesis that "virtual" electrophysiological studies (EPS) on an anatomic platform generated by 3-dimensional magnetic resonance imaging reconstruction of the left ventricle can reproduce the reentrant circuits of induced ventricular tachycardia (VT) in a porcine model of myocardial infarction. Delayed-enhancement magnetic resonance imaging has been used to characterize myocardial infarction and "gray zones," which are thought to reflect heterogeneous regions of viable and nonviable myocytes. Myocardial infarction by coronary artery occlusion was induced in 8 pigs. After a recovery period, 3-dimensional cardiac magnetic resonance images were obtained from each pig in vivo. Normal areas, gray zones, and infarct cores were classified based on voxel intensity. In the computer model, gray zones were assigned slower conduction and longer action potential durations than those for normal myocardium. Virtual EPS was performed and compared with results of actual in vivo programmed stimulation and noncontact mapping. The left ventricular volumes ranged from 97.8 to 166.2 cm(3), with 4.9% to 17.5% of voxels classified as infarct zones. Six of the 7 pigs in which VT developed during actual EPS were also inducible with virtual EPS. Four of the 6 pigs that had simulated VT had reentrant circuits that approximated the circuits seen with noncontact mapping, whereas the remaining 2 had similar circuits but propagating in opposite directions. This initial study demonstrates the feasibility of applying a mathematical model to magnetic resonance imaging reconstructions of the left ventricle to predict VT circuits. Virtual EPS may be helpful to plan catheter ablation strategies or to identify patients who are at risk of future episodes of VT. Copyright © 2012 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  12. Photoprotection by pistachio bioactives in a 3-dimensional human skin equivalent tissue model.

    PubMed

    Chen, C-Y Oliver; Smith, Avi; Liu, Yuntao; Du, Peng; Blumberg, Jeffrey B; Garlick, Jonathan

    2017-01-25

    Reactive oxygen species (ROS) generated during ultraviolet (UV) light exposure can induce skin damage and aging. Antioxidants can provide protection against oxidative injury to skin via "quenching" ROS. Using a validated 3-dimensional (3D) human skin equivalent (HSE) tissue model that closely mimics human skin, we examined whether pistachio antioxidants could protect HSE against UVA-induced damage. Lutein and γ-tocopherol are the predominant lipophilic antioxidants in pistachios; treatment with these compounds prior to UVA exposure protected against morphological changes to the epithelial and connective tissue compartments of HSE. Pistachio antioxidants preserved overall skin thickness and organization, as well as fibroblast morphology, in HSE exposed to UVA irradiation. However, this protection was not substantiated by the analysis of the proliferation of keratinocytes and apoptosis of fibroblasts. Additional studies are warranted to elucidate the basis of these discordant results and extend research into the potential role of pistachio bioactives promoting skin health.

  13. Simple computer program to model 3-dimensional underground heat flow with realistic boundary conditions

    NASA Astrophysics Data System (ADS)

    Metz, P. D.

    A FORTRAN computer program called GROCS (GRound Coupled Systems) has been developed to study 3-dimensional underground heat flow. Features include the use of up to 30 finite elements or blocks of Earth which interact via finite difference heat flow equations and a subprogram which sets realistic time and depth dependent boundary conditions. No explicit consideration of mositure movement or freezing is given. GROCS has been used to model the thermal behavior of buried solar heat storage tanks (with and without insulation) and serpentine pipe fields for solar heat pump space conditioning systems. The program is available independently or in a form compatible with specially written TRNSYS component TYPE subroutines. The approach taken in the design of GROCS, the mathematics contained and the program architecture, are described. Then, the operation of the stand-alone version is explained. Finally, the validity of GROCS is discussed.

  14. [Establishment of 3-dimensional finite element model of human knee joint and its biomechanics].

    PubMed

    Yuan, Ping; Wang, Wanchun

    2010-01-01

    To establish a 3-dimensional (3-D) finite element knee model in healthy Chinese males, to verify the validity of the model, and to analyze the biomechanics of this model under axial load, flexion moment, varus/valgus torque, and internal/external axial torque. A set of consecutive transectional computerized tomography images of normal male knee joints in upright weight-bearing position was selected. With image processing and inversion technology, the 3-D finite element model of the normal knee joint was established through the software ABAQOUS/STANDARD Version-6.5.Biomechanical analysis of this model was processed under axial load, flexion moment, varus/valgus torque, and internal/external axial torque. A 3-D finite element model of healthy Chinese males was successfully established. The ranges of motion of varus and valgus were both small and the difference between them has no statistical significance (P>0.05). The motion of internal and external rotation of the knee took place only in flexion situation.The range of motion of external rotation was larger than that of internal rotation in the same knee (P<0.05). The 3-D geometrical model of the knee resembles the actual knee segments. It can imitate the knee response to different loads. This model could be used for further study on knee biomechanics.

  15. In situ time-resolved SAXS study of the formation of mesostructured organically modified silica through modeling of micelles evolution during surfactant-templated self-assembly.

    PubMed

    Michaux, Florentin; Baccile, Niki; Impéror-Clerc, Marianne; Malfatti, Luca; Folliet, Nicolas; Gervais, Christel; Manet, Sabine; Meneau, Florian; Pedersen, Jan Skov; Babonneau, Florence

    2012-12-18

    The mechanisms of formation of organically modified (phenyl, vinyl, and methyl) silica materials with cubic Pm3n and hexagonal p6m periodic mesostructures obtained in one step in the presence of the cetyltrimethylammonium bromide (CTA(+)B) surfactant are reported in this study. Understanding the way these complex materials form is difficult but undoubtedly necessary for controlling the material structure and its properties because of the combined presence of surface organic groups and large surface areas. Here, the mechanism of formation is clarified on the basis of the modeling of time-resolved in situ small angle X-ray scattering (SAXS) experiments, with a specific focus on the micelle evolution during material formation. Their fast self-assembly is followed for the first time with a quick temporal resolution of a few seconds using a third-generation synchrotron radiation source. To better understand the behavior of the complex organic-containing mesostructure, we perform a comparative study with the corresponding organo-free, isostructural materials obtained from three different surfactants (CTA(+), CTEA(+), and CTPA(+)) having a constant chain length (C(16)) and an increasing polar head volume (met-, et-, and prop-). Numerical modeling of SAXS data was crucial to highlighting a systematic sphere-to-rod micellar transition, otherwise undetected, before the formation of the 2D hexagonal phase in both organo-free and organo-containing systems. Then, two different pathways were found in the formation of the cubic Pm3n mesostructure: either an ordering transition from concentrated flocs of spherical micelles (from CTEA(+) or CTPA(+)) for pure TEOS systems or a structural transformation from an intermediate 2D hexagonal mesophase in organosilane systems (from CTA(+)). Combining the comparison between organo-free and organo-containing systems with numerical modeling, we find that the hexagonal-to-cubic phase transition in the organically modified materials seems to be

  16. Assessment and Planning for a Pediatric Bilateral Hand Transplant Using 3-Dimensional Modeling: Case Report.

    PubMed

    Gálvez, Jorge A; Gralewski, Kevin; McAndrew, Christine; Rehman, Mohamed A; Chang, Benjamin; Levin, L Scott

    2016-03-01

    Children are not typically considered for hand transplantation for various reasons, including the difficulty of finding an appropriate donor. Matching donor-recipient hands and forearms based on size is critically important. If the donor's hands are too large, the recipient may not be able to move the fingers effectively. Conversely, if the donor's hands are too small, the appearance may not be appropriate. We present an 8-year-old child evaluated for a bilateral hand transplant following bilateral amputation. The recipient forearms and model hands were modeled from computed tomography imaging studies and replicated as anatomic models with a 3-dimensional printer. We modified the scale of the printed hand to produce 3 proportions, 80%, 100% and 120%. The transplant team used the anatomical models during evaluation of a donor for appropriate match based on size. The donor's hand size matched the 100%-scale anatomical model hand and the transplant team was activated. In addition to assisting in appropriate donor selection by the transplant team, the 100%-scale anatomical model hand was used to create molds for prosthetic hands for the donor.

  17. A 3-dimensional DTI MRI-based model of GBM growth and response to radiation therapy.

    PubMed

    Hathout, Leith; Patel, Vishal; Wen, Patrick

    2016-09-01

    Glioblastoma (GBM) is both the most common and the most aggressive intra-axial brain tumor, with a notoriously poor prognosis. To improve this prognosis, it is necessary to understand the dynamics of GBM growth, response to treatment and recurrence. The present study presents a mathematical diffusion-proliferation model of GBM growth and response to radiation therapy based on diffusion tensor (DTI) MRI imaging. This represents an important advance because it allows 3-dimensional tumor modeling in the anatomical context of the brain. Specifically, tumor infiltration is guided by the direction of the white matter tracts along which glioma cells infiltrate. This provides the potential to model different tumor growth patterns based on location within the brain, and to simulate the tumor's response to different radiation therapy regimens. Tumor infiltration across the corpus callosum is simulated in biologically accurate time frames. The response to radiation therapy, including changes in cell density gradients and how these compare across different radiation fractionation protocols, can be rendered. Also, the model can estimate the amount of subthreshold tumor which has extended beyond the visible MR imaging margins. When combined with the ability of being able to estimate the biological parameters of invasiveness and proliferation of a particular GBM from serial MRI scans, it is shown that the model has potential to simulate realistic tumor growth, response and recurrence patterns in individual patients. To the best of our knowledge, this is the first presentation of a DTI-based GBM growth and radiation therapy treatment model.

  18. Using Interior Point Method Optimization Techniques to Improve 2- and 3-Dimensional Models of Earth Structures

    NASA Astrophysics Data System (ADS)

    Zamora, A.; Gutierrez, A. E.; Velasco, A. A.

    2014-12-01

    2- and 3-Dimensional models obtained from the inversion of geophysical data are widely used to represent the structural composition of the Earth and to constrain independent models obtained from other geological data (e.g. core samples, seismic surveys, etc.). However, inverse modeling of gravity data presents a very unstable and ill-posed mathematical problem, given that solutions are non-unique and small changes in parameters (position and density contrast of an anomalous body) can highly impact the resulting model. Through the implementation of an interior-point method constrained optimization technique, we improve the 2-D and 3-D models of Earth structures representing known density contrasts mapping anomalous bodies in uniform regions and boundaries between layers in layered environments. The proposed techniques are applied to synthetic data and gravitational data obtained from the Rio Grande Rift and the Cooper Flat Mine region located in Sierra County, New Mexico. Specifically, we improve the 2- and 3-D Earth models by getting rid of unacceptable solutions (those that do not satisfy the required constraints or are geologically unfeasible) given the reduction of the solution space.

  19. The Effectiveness of an Interactive 3-Dimensional Computer Graphics Model for Medical Education

    PubMed Central

    Konishi, Takeshi; Tamura, Yoko; Moriguchi, Hiroki

    2012-01-01

    Background Medical students often have difficulty achieving a conceptual understanding of 3-dimensional (3D) anatomy, such as bone alignment, muscles, and complex movements, from 2-dimensional (2D) images. To this end, animated and interactive 3-dimensional computer graphics (3DCG) can provide better visual information to users. In medical fields, research on the advantages of 3DCG in medical education is relatively new. Objective To determine the educational effectiveness of interactive 3DCG. Methods We divided 100 participants (27 men, mean (SD) age 17.9 (0.6) years, and 73 women, mean (SD) age 18.1 (1.1) years) from the Health Sciences University of Mongolia (HSUM) into 3DCG (n = 50) and textbook-only (control) (n = 50) groups. The control group used a textbook and 2D images, while the 3DCG group was trained to use the interactive 3DCG shoulder model in addition to a textbook. We conducted a questionnaire survey via an encrypted satellite network between HSUM and Tokushima University. The questionnaire was scored on a 5-point Likert scale from strongly disagree (score 1) to strongly agree (score 5). Results Interactive 3DCG was effective in undergraduate medical education. Specifically, there was a significant difference in mean (SD) scores between the 3DCG and control groups in their response to questionnaire items regarding content (4.26 (0.69) vs 3.85 (0.68), P = .001) and teaching methods (4.33 (0.65) vs 3.74 (0.79), P < .001), but no significant difference in the Web category. Participants also provided meaningful comments on the advantages of interactive 3DCG. Conclusions Interactive 3DCG materials have positive effects on medical education when properly integrated into conventional education. In particular, our results suggest that interactive 3DCG is more efficient than textbooks alone in medical education and can motivate students to understand complex anatomical structures. PMID:23611759

  20. The effectiveness of an interactive 3-dimensional computer graphics model for medical education.

    PubMed

    Battulga, Bayanmunkh; Konishi, Takeshi; Tamura, Yoko; Moriguchi, Hiroki

    2012-07-09

    Medical students often have difficulty achieving a conceptual understanding of 3-dimensional (3D) anatomy, such as bone alignment, muscles, and complex movements, from 2-dimensional (2D) images. To this end, animated and interactive 3-dimensional computer graphics (3DCG) can provide better visual information to users. In medical fields, research on the advantages of 3DCG in medical education is relatively new. To determine the educational effectiveness of interactive 3DCG. We divided 100 participants (27 men, mean (SD) age 17.9 (0.6) years, and 73 women, mean (SD) age 18.1 (1.1) years) from the Health Sciences University of Mongolia (HSUM) into 3DCG (n = 50) and textbook-only (control) (n = 50) groups. The control group used a textbook and 2D images, while the 3DCG group was trained to use the interactive 3DCG shoulder model in addition to a textbook. We conducted a questionnaire survey via an encrypted satellite network between HSUM and Tokushima University. The questionnaire was scored on a 5-point Likert scale from strongly disagree (score 1) to strongly agree (score 5). Interactive 3DCG was effective in undergraduate medical education. Specifically, there was a significant difference in mean (SD) scores between the 3DCG and control groups in their response to questionnaire items regarding content (4.26 (0.69) vs 3.85 (0.68), P = .001) and teaching methods (4.33 (0.65) vs 3.74 (0.79), P < .001), but no significant difference in the Web category. Participants also provided meaningful comments on the advantages of interactive 3DCG. Interactive 3DCG materials have positive effects on medical education when properly integrated into conventional education. In particular, our results suggest that interactive 3DCG is more efficient than textbooks alone in medical education and can motivate students to understand complex anatomical structures.

  1. Superimposition of 3-dimensional cone-beam computed tomography models of growing patients

    PubMed Central

    Cevidanes, Lucia H. C.; Heymann, Gavin; Cornelis, Marie A.; DeClerck, Hugo J.; Tulloch, J. F. Camilla

    2009-01-01

    Introduction The objective of this study was to evaluate a new method for superimposition of 3-dimensional (3D) models of growing subjects. Methods Cone-beam computed tomography scans were taken before and after Class III malocclusion orthopedic treatment with miniplates. Three observers independently constructed 18 3D virtual surface models from cone-beam computed tomography scans of 3 patients. Separate 3D models were constructed for soft-tissue, cranial base, maxillary, and mandibular surfaces. The anterior cranial fossa was used to register the 3D models of before and after treatment (about 1 year of follow-up). Results Three-dimensional overlays of superimposed models and 3D color-coded displacement maps allowed visual and quantitative assessment of growth and treatment changes. The range of interobserver errors for each anatomic region was 0.4 mm for the zygomatic process of maxilla, chin, condyles, posterior border of the rami, and lower border of the mandible, and 0.5 mm for the anterior maxilla soft-tissue upper lip. Conclusions Our results suggest that this method is a valid and reproducible assessment of treatment outcomes for growing subjects. This technique can be used to identify maxillary and mandibular positional changes and bone remodeling relative to the anterior cranial fossa. PMID:19577154

  2. Modeling Biofilm-Induced Hydraulic Changes In 3-Dimensional Prefractal Porous Media

    NASA Astrophysics Data System (ADS)

    Kim, J.; Choi, H.; Perfect, E.; Pachepsky, Y. A.

    2008-12-01

    Biofilm-induced clogging is the significant phenomenon in subsurface hydrology that may affect aquifer recharge and solute transport. Modeling biofilm impact on flow and transport at pore scale should include characterization of the heterogeneity of both biofilm and medium. In this study, a numerical model of biofilm- induced hydraulic changes in porous media was developed based on the individual-based model (IbM) for the biofilm growth according to the Monod equation, and the Lattice Boltzmann model (LBM) for the water flow. The LBM was modified to consider biofilm growth in each grid cell, and IbM was synchronized with the LBM. The model behavior was first investigated for simple geometry of the prismatic void space with constant flow and concentration boundary conditions at the inflow boundary, no-gradient condition on the outflow side, and periodic boundary condition on the other sides. The mass conservation was tested by varying Peclet number and computing the solute breakthrough. The breakthrough was retarded when a solid sphere was placed in the prism, and the retardation was increasing as flow velocity was increasing. Increase in the biofilm volume surrounding solid sphere increased pressure at the windward side of sphere, and the flow velocity in the narrow passage between biofilms was increased. The biofilm grew more vigorously on the windward side compared with the leeward side of the sphere because the biofilm growth interrupted the supply of the dissolved substrate to the leeward side. Darcy relation was better to estimate hydraulic conductivity than Kozeny-Carman relation which assumes that biofilms are uniformly distributed on the surface. Finally, 3- dimensional mass and pore-solid prefractal lattices as models of heterogeneous porous media were generated by iterated function system and used as the simulation domain. The flow in these domains reached the steady state at threshold porosities (hydrostatic threshold) that were estimated to be about 0

  3. A 3-dimensional rigid cluster thorax model for kinematic measurements during gait.

    PubMed

    Kiernan, D; Malone, A; O'Brien, T; Simms, C K

    2014-04-11

    The trunk has been shown to work as an active segment rather than a passenger unit during gait and it is felt that trunk kinematics should be given more consideration during gait assessment. While 3-dimensional assessment of the thorax with respect to the pelvis and laboratory can provide a comprehensive description of trunk movement, the majority of existing 3-D thorax models demonstrate shortcomings such as the need for multiple skin marker configurations, difficult landmark identification and practical issues for assessment on female subjects. A small number of studies have used rigid cluster models to quantify thorax movement, however the models and points of attachment are not well described and validation rarely considered. The aim of this study was to propose an alternative rigid cluster 3-D thorax model to quantify movement during gait and provide validation of this model. A rigid mount utilising active markers was developed and applied over the 3rd thoracic vertebra, previously reported as an area of least skin movement artefact on the trunk. The model was compared to two reference thorax models through simultaneous recording during gait on 15 healthy subjects. Excellent waveform similarity was demonstrated between the proposed model and the two reference models (CMC range 0.962-0.997). Agreement of discrete parameters was very-good to excellent. In addition, ensemble average graphs demonstrated almost identical curve displacement between models. The results suggest that the proposed model can be confidently used as an alternative to other thorax models in the clinical setting. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. 3-Dimensional Modeling of Capacitively and Inductively Coupled Plasma Etching Systems

    NASA Astrophysics Data System (ADS)

    Rauf, Shahid

    2008-10-01

    Low temperature plasmas are widely used for thin film etching during micro and nano-electronic device fabrication. Fluid and hybrid plasma models were developed 15-20 years ago to understand the fundamentals of these plasmas and plasma etching. These models have significantly evolved since then, and are now a major tool used for new plasma hardware design and problem resolution. Plasma etching is a complex physical phenomenon, where inter-coupled plasma, electromagnetic, fluid dynamics, and thermal effects all have a major influence. The next frontier in the evolution of fluid-based plasma models is where these models are able to self-consistently treat the inter-coupling of plasma physics with fluid dynamics, electromagnetics, heat transfer and magnetostatics. We describe one such model in this paper and illustrate its use in solving engineering problems of interest for next generation plasma etcher design. Our 3-dimensional plasma model includes the full set of Maxwell equations, transport equations for all charged and neutral species in the plasma, the Navier-Stokes equation for fluid flow, and Kirchhoff's equations for the lumped external circuit. This model also includes Monte Carlo based kinetic models for secondary electrons and stochastic heating, and can take account of plasma chemistry. This modeling formalism allows us to self-consistently treat the dynamics in commercial inductively and capacitively coupled plasma etching reactors with realistic plasma chemistries, magnetic fields, and reactor geometries. We are also able to investigate the influence of the distributed electromagnetic circuit at very high frequencies (VHF) on the plasma dynamics. The model is used to assess the impact of azimuthal asymmetries in plasma reactor design (e.g., off-center pump, 3D magnetic field, slit valve, flow restrictor) on plasma characteristics at frequencies from 2 -- 180 MHz. With Jason Kenney, Ankur Agarwal, Ajit Balakrishna, Kallol Bera, and Ken Collins.

  5. An Innovative 3-dimensional Model of the Epitympanum for Teaching of Middle Ear Anatomy.

    PubMed

    Ng, Chew Lip; Liu, Xuandao; Chee, Shuo Chian Jeremy; Ngo, Raymond Yeow Seng

    2015-11-01

    To facilitate teaching of the anatomy of the epitympanum, we developed and evaluated the effectiveness of an interactive 3-dimensional (3D) computer model that can be viewed from all angles. Questionnaire-based prospective randomized controlled trial. Undergraduate medical education program. The model was created using Google Sketchup, a 3D modeling software. We recruited 72 graduating medical students and randomized them into 2 groups. One group was given the 3D model and reading materials on the epitympanic anatomy (3D group), while the other group relied on reading material and pictures (2-dimensional [2D] group). A questionnaire and anatomy quiz assessed the utility of the 3D model in learning the anatomy of the epitympanum. The mean age of the participants was 22 years. There were no statistically significant differences in demographics and previous experience with 3D models. The 3D group was significantly more confident in its ability to identify structures of the epitympanum on pictures and computed tomography scans when compared to the 2D group. Most participants were in favor of the model as a useful learning tool and preferred to use it with an instructor. In the anatomy quiz, the 3D group fared significantly better, achieving a mean score of 65.1% compared to 32.4% in the 2D group (P < .001). The 3D teaching model of the epitympanum is efficacious in short-term recall. By allowing the learner to visualize relations of the epitympanum from all directions, the model aids in appreciation of anatomy and identifications of structures of this region. © American Academy of Otolaryngology—Head and Neck Surgery Foundation 2015.

  6. Time Resolved Deposition Measurements in NSTX

    SciTech Connect

    C.H. Skinner; H. Kugel; A.L. Roquemore; J. Hogan; W.R. Wampler; the NSTX team

    2004-08-03

    Time-resolved measurements of deposition in current tokamaks are crucial to gain a predictive understanding of deposition with a view to mitigating tritium retention and deposition on diagnostic mirrors expected in next-step devices. Two quartz crystal microbalances have been installed on NSTX at a location 0.77m outside the last closed flux surface. This configuration mimics a typical diagnostic window or mirror. The deposits were analyzed ex-situ and found to be dominantly carbon, oxygen, and deuterium. A rear facing quartz crystal recorded deposition of lower sticking probability molecules at 10% of the rate of the front facing one. Time resolved measurements over a 4-week period with 497 discharges, recorded 29.2 {micro}g/cm{sup 2} of deposition, however surprisingly, 15.9 {micro}g/cm{sup 2} of material loss occurred at 7 discharges. The net deposited mass of 13.3 {micro}g/cm{sup 2} matched the mass of 13.5 {micro}g/cm{sup 2} measured independently by ion beam analysis. Monte Carlo modeling suggests that transient processes are likely to dominate the deposition.

  7. An integrated 3-Dimensional Genome Modeling Engine for data-driven simulation of spatial genome organization

    PubMed Central

    Szałaj, Przemysław; Tang, Zhonghui; Michalski, Paul; Pietal, Michal J.; Luo, Oscar J.; Sadowski, Michał; Li, Xingwang; Radew, Kamen; Ruan, Yijun; Plewczynski, Dariusz

    2016-01-01

    ChIA-PET is a high-throughput mapping technology that reveals long-range chromatin interactions and provides insights into the basic principles of spatial genome organization and gene regulation mediated by specific protein factors. Recently, we showed that a single ChIA-PET experiment provides information at all genomic scales of interest, from the high-resolution locations of binding sites and enriched chromatin interactions mediated by specific protein factors, to the low resolution of nonenriched interactions that reflect topological neighborhoods of higher-order chromosome folding. This multilevel nature of ChIA-PET data offers an opportunity to use multiscale 3D models to study structural-functional relationships at multiple length scales, but doing so requires a structural modeling platform. Here, we report the development of 3D-GNOME (3-Dimensional Genome Modeling Engine), a complete computational pipeline for 3D simulation using ChIA-PET data. 3D-GNOME consists of three integrated components: a graph-distance-based heat map normalization tool, a 3D modeling platform, and an interactive 3D visualization tool. Using ChIA-PET and Hi-C data derived from human B-lymphocytes, we demonstrate the effectiveness of 3D-GNOME in building 3D genome models at multiple levels, including the entire genome, individual chromosomes, and specific segments at megabase (Mb) and kilobase (kb) resolutions of single average and ensemble structures. Further incorporation of CTCF-motif orientation and high-resolution looping patterns in 3D simulation provided additional reliability of potential biologically plausible topological structures. PMID:27789526

  8. An integrated 3-Dimensional Genome Modeling Engine for data-driven simulation of spatial genome organization.

    PubMed

    Szałaj, Przemysław; Tang, Zhonghui; Michalski, Paul; Pietal, Michal J; Luo, Oscar J; Sadowski, Michał; Li, Xingwang; Radew, Kamen; Ruan, Yijun; Plewczynski, Dariusz

    2016-12-01

    ChIA-PET is a high-throughput mapping technology that reveals long-range chromatin interactions and provides insights into the basic principles of spatial genome organization and gene regulation mediated by specific protein factors. Recently, we showed that a single ChIA-PET experiment provides information at all genomic scales of interest, from the high-resolution locations of binding sites and enriched chromatin interactions mediated by specific protein factors, to the low resolution of nonenriched interactions that reflect topological neighborhoods of higher-order chromosome folding. This multilevel nature of ChIA-PET data offers an opportunity to use multiscale 3D models to study structural-functional relationships at multiple length scales, but doing so requires a structural modeling platform. Here, we report the development of 3D-GNOME (3-Dimensional Genome Modeling Engine), a complete computational pipeline for 3D simulation using ChIA-PET data. 3D-GNOME consists of three integrated components: a graph-distance-based heat map normalization tool, a 3D modeling platform, and an interactive 3D visualization tool. Using ChIA-PET and Hi-C data derived from human B-lymphocytes, we demonstrate the effectiveness of 3D-GNOME in building 3D genome models at multiple levels, including the entire genome, individual chromosomes, and specific segments at megabase (Mb) and kilobase (kb) resolutions of single average and ensemble structures. Further incorporation of CTCF-motif orientation and high-resolution looping patterns in 3D simulation provided additional reliability of potential biologically plausible topological structures.

  9. [Constructing 3-dimensional colorized digital dental model assisted by digital photography].

    PubMed

    Ye, Hong-qiang; Liu, Yu-shu; Liu, Yun-song; Ning, Jing; Zhao, Yi-jiao; Zhou, Yong-sheng

    2016-02-18

    To explore a method of constructing universal 3-dimensional (3D) colorized digital dental model which can be displayed and edited in common 3D software (such as Geomagic series), in order to improve the visual effect of digital dental model in 3D software. The morphological data of teeth and gingivae were obtained by intra-oral scanning system (3Shape TRIOS), constructing 3D digital dental models. The 3D digital dental models were exported as STL files. Meanwhile, referring to the accredited photography guide of American Academy of Cosmetic Dentistry (AACD), five selected digital photographs of patients'teeth and gingivae were taken by digital single lens reflex camera (DSLR) with the same exposure parameters (except occlusal views) to capture the color data. In Geomagic Studio 2013, after STL file of 3D digital dental model being imported, digital photographs were projected on 3D digital dental model with corresponding position and angle. The junctions of different photos were carefully trimmed to get continuous and natural color transitions. Then the 3D colorized digital dental model was constructed, which was exported as OBJ file or WRP file which was a special file for software of Geomagic series. For the purpose of evaluating the visual effect of the 3D colorized digital model, a rating scale on color simulation effect in views of patients'evaluation was used. Sixteen patients were recruited and their scores on colored and non-colored digital dental models were recorded. The data were analyzed using McNemar-Bowker test in SPSS 20. Universal 3D colorized digital dental model with better color simulation was constructed based on intra-oral scanning and digital photography. For clinical application, the 3D colorized digital dental models, combined with 3D face images, were introduced into 3D smile design of aesthetic rehabilitation, which could improve the patients' cognition for the esthetic digital design and virtual prosthetic effect. Universal 3D colorized

  10. Influence of standardization on the precision (reproducibility) of dental cast analysis with virtual 3-dimensional models.

    PubMed

    Hayashi, Kazuo; Chung, Onejune; Park, Seojung; Lee, Seung-Pyo; Sachdeva, Rohit C L; Mizoguchi, Itaru

    2015-03-01

    Virtual 3-dimensional (3D) models obtained by scanning of physical casts have become an alternative to conventional dental cast analysis in orthodontic treatment. If the precision (reproducibility) of virtual 3D model analysis can be further improved, digital orthodontics could be even more widely accepted. The purpose of this study was to clarify the influence of "standardization" of the target points for dental cast analysis using virtual 3D models. Physical plaster models were also measured to obtain additional information. Five sets of dental casts were used. The dental casts were scanned with R700 (3Shape, Copenhagen, Denmark) and REXCAN DS2 3D (Solutionix, Seoul, Korea) scanners. In this study, 3 system and software packages were used: SureSmile (OraMetrix, Richardson, Tex), Rapidform (Inus, Seoul, Korea), and I-DEAS (SDRC, Milford, Conn). Without standardization, the maximum differences were observed between the SureSmile software and the Rapidform software (0.39 mm ± 0.07). With standardization, the maximum differences were observed between the SureSmile software and measurements with a digital caliper (0.099 mm ± 0.01), and this difference was significantly greater (P <0.05) than the 2 other mean difference values. Furthermore, the results of this study showed that the mean differences "WITH" standardization were significantly lower than those "WITHOUT" standardization for all systems, software packages, or methods. The results showed that elimination of the influence of usability or habituation is important for improving the reproducibility of dental cast analysis. Copyright © 2015 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

  11. Evaluation of Nitinol Stents Using a 3-Dimensional Printed Superficial Femoral Artery Model: A Preliminary Study.

    PubMed

    Girsowicz, Elie; Georg, Yannick; Seiller, Hélène; Lejay, Anne; Thaveau, Fabien; Heim, Frédéric; Chakfe, Nabil

    2016-05-01

    Mechanical tests assessing Nitinol stents used for the superficial femoral artery (SFA) are designed without taking into account their deployment environments. The objectives of this study were (1) to create normal and pathologic femoral artery models, (2) to run mechanical tests reproducing the stresses of the SFA, and (3) to study and compare Nitinol stents in those conditions. Femoral artery models with identical mechanical properties to the SFA were created using the 3-dimensional printing technology. Those models were designed with and without an asymmetric focal 50% stenosis. Three mechanical tests (bending-compression, bending-compression-torsion, and multiple bending tests) were created and 1 flexible stent was tested, of 6 and 7-mm diameter. Three samples of the stent, LifeStent (Bard(®)), were deployed and tested in the models. Stents alone were evaluated in the same conditions. The analysis focused on the comparison of rheologic curves, level of kink, and the energy deployed for each stent to kink. In the 3 tests, all stents deployed in the models presented a kink during their evaluation. When tested alone, during the compression-bending and bending-compression-torsion tests, no plicature was observed. During the multiple bending test, the energy deployed to plicature for the stent tested alone was of 1.4 ± 0.10 and 2.84 ± 0.1 J compared with 9.7 ± 0.6 and 8.25 ± 0.6 J when deployed in the model for the Lifestent 6 × 80 and 7 × 80 mm, respectively. For all of these 3 tests, 6-mm diameter stents exhibited a level of kink and energy of kink higher than 7 mm stents. The behavior of the stents changed in the stenosed model whatever diameter is taken into account. Analysis of the rheologic curves showed a decrease in the inflection of the curve related to the plication. In the bending-compression test, the presence of a stenosis lead to an early plication of the model, with less deployed kinking energy whereas in the bending

  12. Fenofibrate inhibits tumour intravasation by several independent mechanisms in a 3-dimensional co-culture model.

    PubMed

    Nguyen, Chi Huu; Huttary, Nicole; Atanasov, Atanas G; Chatuphonprasert, Waranya; Brenner, Stefan; Fristiohady, Adryan; Hong, Junli; Stadler, Serena; Holzner, Silvio; Milovanovic, Daniela; Dirsch, Verena M; Kopp, Brigitte; Saiko, Philipp; Krenn, Liselotte; Jäger, Walter; Krupitza, Georg

    2017-05-01

    Lymph node metastasis of breast cancer is a clinical marker of poor prognosis. Yet, there exist no therapies targeting mechanisms of intravasation into lymphatics. Herein we report on an effect of the antidyslipidemic drug fenofibrate with vasoprotective activity, which attenuates breast cancer intravasation in vitro, and describe the potential mechanisms. To measure intravasation in a 3-dimensional co-culture model MDA-MB231 and MCF-7 breast cancer spheroids were placed on immortalised lymphendothelial cell (LEC) monolayers. This provokes the formation of circular chemorepellent induced defects (CCIDs) in the LEC barrier resembling entry ports for the intravasating tumour. Furthermore, the expression of adhesion molecules ICAM-1, CD31 and FAK was investigated in LECs by western blotting as well as cell-cell adhesion and NF-κB activity by respective assays. In MDA-MB231 cells the activity of CYP1A1 was measured by EROD assay. Fenofibrate inhibited CCID formation in the MDA-MB231/LEC- and MCF-7/LEC models and the activity of NF-κB, which in turn downregulated ICAM-1 in LECs and the adhesion of cancer cells to LECs. Furthermore, CD31 and the activity of FAK were inhibited. In MDA-MB231 cells, fenofibrate attenuated CYP1A1 activity. Combinations with other FDA-approved drugs, which reportedly inhibit different ion channels, attenuated CCID formation additively or synergistically. In summary, fenofibrate inhibited NF-κB and ICAM-1, and inactivated FAK, thereby attenuating tumour intravasation in vitro. A combination with other FDA-approved drugs further improved this effect. Our new concept may lead to a novel therapy for cancer patients.

  13. Static and time-resolved step-scan Fourier transform infrared investigations of the photoreaction of halorhodopsin from Natronobacterium pharaonis: consequences for models of the anion translocation mechanism.

    PubMed Central

    Hackmann, C; Guijarro, J; Chizhov, I; Engelhard, M; Rödig, C; Siebert, F

    2001-01-01

    The molecular changes during the photoreaction of halorhodopsin from Natronobacterium pharaonis have been monitored by low-temperature static and by time-resolved step-scan Fourier transform infrared difference spectroscopy. In the low-temperature L spectrum anions only influence a band around 1650 cm(-1), tentatively assigned to the C=N stretch of the protonated Schiff base of L. The analysis of the time-resolved spectra allows to identify the four states: K, L(1), L(2), and O. Between L(1) and L(2), only the apoprotein undergoes alterations. The O state is characterized by an all-trans chromophore and by rather large amide I spectral changes. Because in our analysis the intermediate containing O is in equilibrium with a state indistinguishable from L(2), we are unable to identify an N-like state. At very high chloride concentrations (>5 M), we observe a branching of the photocycle from L(2) directly back to the dark state, and we provide evidence for direct back-isomerization from L(2). This branching leads to the reported reduction of transport activity at such high chloride concentrations. We interpret the L(1) to L(2) transition as an accessibility change of the anion from the extracellular to the cytosolic side, and the large amide I bands in O as an indication for opening of the cytosolic channel from the Schiff base toward the cytosolic surface and/or as indication for changes of the binding constant of the release site. PMID:11423423

  14. Benefits and Limitations of Entry-Level 3-Dimensional Printing of Maxillofacial Skeletal Models.

    PubMed

    Legocki, Alex T; Duffy-Peter, Andrew; Scott, Andrew R

    2017-04-01

    A protocol for creating exceptionally low-cost 3-dimensional (3-D) maxillofacial skeletal models does not require proficiency with computer software or intensive labor. Small and less affluent centers can produce models with little loss in accuracy and clinical utility. To highlight the feasibility and methods of introducing in-house, entry-level additive manufacturing (3-D printing) technology to otolaryngologic craniofacial reconstruction and to describe its clinical applications and limitations, including a comparison with available vendor models. This case series of 6 models (3 pairs) compared cost, side-by-side anatomical model fidelity, and clinical versatility using entry-level, in-house 3-D pediatric mandible model production vs high-end, third-party vendor modeling, including a review of the literature. Comparisons were made at an urban pediatric otolaryngology practice among patients who had previously undergone pediatric craniofacial reconstruction with use of a commercially produced medical model for surgical planning. Each vendor model had been produced using computed tomographic imaging data. With the use of this same data source, in-house models were printed in polylactic acid using a commercially available printer. Data were collected from November 1 to December 30, 2015. Models created from these 2 methods of production were assessed for fidelity of surface anatomy, resilience to manipulation and plate bending, cost of production, speed of production, sterilizability, virtual surgical planning options, and alveolar nerve canal and tooth root visibility in mandibles. For the quantitative comparisons between in-house models (1 neonatal, 1 pediatric, and 1 adult model) and their commercial counterparts, the mean value of 7 independent measurements was analyzed from each of 3 model pairs. Caliper measurements from models produced through entry-level, in-house manufacturing were comparable to those taken from commercially produced counterparts

  15. First Results from a Forward, 3-Dimensional Regional Model of a Transpressional San Andreas Fault System

    NASA Astrophysics Data System (ADS)

    Fitzenz, D. D.; Miller, S. A.

    2001-12-01

    We present preliminary results from a 3-dimensional fault interaction model, with the fault system specified by the geometry and tectonics of the San Andreas Fault (SAF) system. We use the forward model for earthquake generation on interacting faults of Fitzenz and Miller [2001] that incorporates the analytical solutions of Okada [85,92], GPS-constrained tectonic loading, creep compaction and frictional dilatancy [Sleep and Blanpied, 1994, Sleep, 1995], and undrained poro-elasticity. The model fault system is centered at the Big Bend, and includes three large strike-slip faults (each discretized into multiple subfaults); 1) a 300km, right-lateral segment of the SAF to the North, 2) a 200km-long left-lateral segment of the Garlock fault to the East, and 3) a 100km-long right-lateral segment of the SAF to the South. In the initial configuration, three shallow-dipping faults are also included that correspond to the thrust belt sub-parallel to the SAF. Tectonic loading is decomposed into basal shear drag parallel to the plate boundary with a 35mm yr-1 plate velocity, and East-West compression approximated by a vertical dislocation surface applied at the far-field boundary resulting in fault-normal compression rates in the model space about 4mm yr-1. Our aim is to study the long-term seismicity characteristics, tectonic evolution, and fault interaction of this system. We find that overpressured faults through creep compaction are a necessary consequence of the tectonic loading, specifically where high normal stress acts on long straight fault segments. The optimal orientation of thrust faults is a function of the strike-slip behavior, and therefore results in a complex stress state in the elastic body. This stress state is then used to generate new fault surfaces, and preliminary results of dynamically generated faults will also be presented. Our long-term aim is to target measurable properties in or around fault zones, (e.g. pore pressures, hydrofractures, seismicity

  16. 3-Dimensional Marine CSEM Modeling by Employing TDFEM with Parallel Solvers

    NASA Astrophysics Data System (ADS)

    Wu, X.; Yang, T.

    2013-12-01

    In this paper, parallel fulfillment is developed for forward modeling of the 3-Dimensional controlled source electromagnetic (CSEM) by using time-domain finite element method (TDFEM). Recently, a greater attention rises on research of hydrocarbon (HC) reservoir detection mechanism in the seabed. Since China has vast ocean resources, seeking hydrocarbon reservoirs become significant in the national economy. However, traditional methods of seismic exploration shown a crucial obstacle to detect hydrocarbon reservoirs in the seabed with a complex structure, due to relatively high acquisition costs and high-risking exploration. In addition, the development of EM simulations typically requires both a deep knowledge of the computational electromagnetics (CEM) and a proper use of sophisticated techniques and tools from computer science. However, the complexity of large-scale EM simulations often requires large memory because of a large amount of data, or solution time to address problems concerning matrix solvers, function transforms, optimization, etc. The objective of this paper is to present parallelized implementation of the time-domain finite element method for analysis of three-dimensional (3D) marine controlled source electromagnetic problems. Firstly, we established a three-dimensional basic background model according to the seismic data, then electromagnetic simulation of marine CSEM was carried out by using time-domain finite element method, which works on a MPI (Message Passing Interface) platform with exact orientation to allow fast detecting of hydrocarbons targets in ocean environment. To speed up the calculation process, SuperLU of an MPI (Message Passing Interface) version called SuperLU_DIST is employed in this approach. Regarding the representation of three-dimension seabed terrain with sense of reality, the region is discretized into an unstructured mesh rather than a uniform one in order to reduce the number of unknowns. Moreover, high-order Whitney

  17. Characterization of chemical contaminants generated by a desktop fused deposition modeling 3-dimensional Printer.

    PubMed

    Stefaniak, Aleksandr B; LeBouf, Ryan F; Yi, Jinghai; Ham, Jason; Nurkewicz, Timothy; Schwegler-Berry, Diane E; Chen, Bean T; Wells, J Raymond; Duling, Matthew G; Lawrence, Robert B; Martin, Stephen B; Johnson, Alyson R; Virji, M Abbas

    2017-07-01

    Printing devices are known to emit chemicals into the indoor atmosphere. Understanding factors that influence release of chemical contaminants from printers is necessary to develop effective exposure assessment and control strategies. In this study, a desktop fused deposition modeling (FDM) 3-dimensional (3-D) printer using acrylonitrile butadiene styrene (ABS) or polylactic acid (PLA) filaments and two monochrome laser printers were evaluated in a 0.5 m(3) chamber. During printing, chamber air was monitored for vapors using a real-time photoionization detector (results expressed as isobutylene equivalents) to measure total volatile organic compound (TVOC) concentrations, evacuated canisters to identify specific VOCs by off-line gas chromatography-mass spectrometry (GC-MS) analysis, and liquid bubblers to identify carbonyl compounds by GC-MS. Airborne particles were collected on filters for off-line analysis using scanning electron microscopy with an energy dispersive x-ray detector to identify elemental constituents. For 3-D printing, TVOC emission rates were influenced by a printer malfunction, filament type, and to a lesser extent, by filament color; however, rates were not influenced by the number of printer nozzles used or the manufacturer's provided cover. TVOC emission rates were significantly lower for the 3-D printer (49-3552 µg h(-1)) compared to the laser printers (5782-7735 µg h(-1)). A total of 14 VOCs were identified during 3-D printing that were not present during laser printing. 3-D printed objects continued to off-gas styrene, indicating potential for continued exposure after the print job is completed. Carbonyl reaction products were likely formed from emissions of the 3-D printer, including 4-oxopentanal. Ultrafine particles generated by the 3-D printer using ABS and a laser printer contained chromium. Consideration of the factors that influenced the release of chemical contaminants (including known and suspected asthmagens such as styrene

  18. Time-Resolved Photoluminescence and Photovoltaics

    SciTech Connect

    Metzger, W. K.; Ahrenkiel, R. K.; Dippo, P.; Geisz, J.; Wanlass, M. W.; Kurtz, S.

    2005-01-01

    The time-resolved photoluminescence (TRPL) technique and its ability to characterize recombination in bulk photovoltaic semiconductor materials are reviewed. Results from a variety of materials and a few recent studies are summarized and compared.

  19. Time resolved thermal lens in edible oils

    NASA Astrophysics Data System (ADS)

    Albuquerque, T. A. S.; Pedreira, P. R. B.; Medina, A. N.; Pereira, J. R. D.; Bento, A. C.; Baesso, M. L.

    2003-01-01

    In this work time resolved thermal lens spectrometry is applied to investigate the optical properties of the following edible oils: soya, sunflower, canola, and corn oils. The experiments were performed at room temperature using the mode mismatched thermal lens configuration. The results showed that when the time resolved procedure is adopted the technique can be applied to investigate the photosensitivity of edible oils. Soya oil presented a stronger photochemical reaction as compared to the other investigated samples. This observation may be relevant for future studies evaluating edible oils storage conditions and also may contribute to a better understanding of the physical and chemical properties of this important foodstuff.

  20. Dissection of the host-pathogen interaction in human tuberculosis using a bioengineered 3-dimensional model

    PubMed Central

    Tezera, Liku B; Bielecka, Magdalena K; Chancellor, Andrew; Reichmann, Michaela T; Shammari, Basim Al; Brace, Patience; Batty, Alex; Tocheva, Annie; Jogai, Sanjay; Marshall, Ben G; Tebruegge, Marc; Jayasinghe, Suwan N; Mansour, Salah; Elkington, Paul T

    2017-01-01

    Cell biology differs between traditional cell culture and 3-dimensional (3-D) systems, and is modulated by the extracellular matrix. Experimentation in 3-D presents challenges, especially with virulent pathogens. Mycobacterium tuberculosis (Mtb) kills more humans than any other infection and is characterised by a spatially organised immune response and extracellular matrix remodelling. We developed a 3-D system incorporating virulent mycobacteria, primary human blood mononuclear cells and collagen–alginate matrix to dissect the host-pathogen interaction. Infection in 3-D led to greater cellular survival and permitted longitudinal analysis over 21 days. Key features of human tuberculosis develop, and extracellular matrix integrity favours the host over the pathogen. We optimised multiparameter readouts to study emerging therapeutic interventions: cytokine supplementation, host-directed therapy and immunoaugmentation. Each intervention modulates the host-pathogen interaction, but has both beneficial and harmful effects. This methodology has wide applicability to investigate infectious, inflammatory and neoplastic diseases and develop novel drug regimes and vaccination approaches. DOI: http://dx.doi.org/10.7554/eLife.21283.001 PMID:28063256

  1. In vitro 3-dimensional tumor model for radiosensitivity of HPV positive OSCC cell lines.

    PubMed

    Zhang, Mei; Rose, Barbara; Lee, C Soon; Hong, Angela M

    2015-01-01

    The incidence of oropharyngeal squamous cell carcinoma (OSCC) is increasing due to the rising prevalence of human papillomavirus (HPV) positive OSCC. HPV positive OSCC is associated with better outcomes than HPV negative OSCC. Our aim was to explore the possibility that this favorable prognosis is due to the enhanced radiosensitivity of HPV positive OSCC. HPV positive OSCC cell lines were generated from the primary OSCCs of 2 patients, and corresponding HPV positive cell lines generated from nodal metastases following xenografting in nude mice. Monolayer and 3 dimensional (3D) culture techniques were used to compare the radiosensitivity of HPV positive lines with that of 2 HPV negative OSCC lines. Clonogenic and protein assays were used to measure survival post radiation. Radiation induced cell cycle changes were studied using flow cytometry. In both monolayer and 3D culture, HPV positive cells exhibited a heterogeneous appearance whereas HPV negative cells tended to be homogeneous. After irradiation, HPV positive cells had a lower survival in clonogenic assays and lower total protein levels in 3D cultures than HPV negative cells. Irradiated HPV positive cells showed a high proportion of cells in G1/S phase, increased apoptosis, an increased proliferation rate, and an inability to form 3D tumor clumps. In conclusion, HPV positive OSCC cells are more radiosensitive than HPV negative OSCC cells in vitro, supporting a more radiosensitive nature of HPV positive OSCC.

  2. Experimental Validation of Plastic Mandible Models Produced by a “Low-Cost” 3-Dimensional Fused Deposition Modeling Printer

    PubMed Central

    Maschio, Federico; Pandya, Mirali; Olszewski, Raphael

    2016-01-01

    Background The objective of this study was to investigate the accuracy of 3-dimensional (3D) plastic (ABS) models generated using a low-cost 3D fused deposition modelling printer. Material/Methods Two human dry mandibles were scanned with a cone beam computed tomography (CBCT) Accuitomo device. Preprocessing consisted of 3D reconstruction with Maxilim software and STL file repair with Netfabb software. Then, the data were used to print 2 plastic replicas with a low-cost 3D fused deposition modeling printer (Up plus 2®). Two independent observers performed the identification of 26 anatomic landmarks on the 4 mandibles (2 dry and 2 replicas) with a 3D measuring arm. Each observer repeated the identifications 20 times. The comparison between the dry and plastic mandibles was based on 13 distances: 8 distances less than 12 mm and 5 distances greater than 12 mm. Results The mean absolute difference (MAD) was 0.37 mm, and the mean dimensional error (MDE) was 3.76%. The MDE decreased to 0.93% for distances greater than 12 mm. Conclusions Plastic models generated using the low-cost 3D printer UPplus2® provide dimensional accuracies comparable to other well-established rapid prototyping technologies. Validated low-cost 3D printers could represent a step toward the better accessibility of rapid prototyping technologies in the medical field. PMID:27003456

  3. Experimental Validation of Plastic Mandible Models Produced by a "Low-Cost" 3-Dimensional Fused Deposition Modeling Printer.

    PubMed

    Maschio, Federico; Pandya, Mirali; Olszewski, Raphael

    2016-03-22

    The objective of this study was to investigate the accuracy of 3-dimensional (3D) plastic (ABS) models generated using a low-cost 3D fused deposition modelling printer. Two human dry mandibles were scanned with a cone beam computed tomography (CBCT) Accuitomo device. Preprocessing consisted of 3D reconstruction with Maxilim software and STL file repair with Netfabb software. Then, the data were used to print 2 plastic replicas with a low-cost 3D fused deposition modeling printer (Up plus 2®). Two independent observers performed the identification of 26 anatomic landmarks on the 4 mandibles (2 dry and 2 replicas) with a 3D measuring arm. Each observer repeated the identifications 20 times. The comparison between the dry and plastic mandibles was based on 13 distances: 8 distances less than 12 mm and 5 distances greater than 12 mm. The mean absolute difference (MAD) was 0.37 mm, and the mean dimensional error (MDE) was 3.76%. The MDE decreased to 0.93% for distances greater than 12 mm. Plastic models generated using the low-cost 3D printer UPplus2® provide dimensional accuracies comparable to other well-established rapid prototyping technologies. Validated low-cost 3D printers could represent a step toward the better accessibility of rapid prototyping technologies in the medical field.

  4. Time-resolved thermal lens spectroscopy with a single-pulsed laser excitation beam: an analytical model for dual-beam mode-mismatched experiments.

    PubMed

    Sabaeian, Mohammad; Rezaei, Hamidreza; Ghalambor-Dezfouli, Abdolmohammad

    2017-02-01

    Pulsed laser beam excitations are more commonly used in thermal lens spectroscopy (TLS) than continuous-wave (CW) ones, because CW excitations limit the measurement to linear absorption processes [J. Opt. A5, 256 (2003)]. In this work, we present a new and full analytical model for a single-pulsed laser excitation dual-beam mode-mismatched TLS for low absorption solid-state and liquid samples. Our model has been based on a new solution of time-dependent heat equation for a finite-radius cylindrical sample exposed to a single-pulsed excitation laser beam. For low absorbent samples, unlike previous models, all aberration terms associated in the thermal lens were taken into account in Fresnel integration. Besides, the model provides a full analytical mathematical expression for the temperature rise, normalized signal intensity, and Z-scan photothermal lens signal. The model was confirmed with experimental data of distilled deionized water with excellent agreement. Therefore, the model allows us to extract thermo-optical properties of samples in an analytical and more accurate way.

  5. Time resolved astronomy with the SALT

    NASA Astrophysics Data System (ADS)

    Buckley, D. A. H.; Crawford, S.; Gulbis, A. A. S.; McPhate, J.; Nordsieck, K. H.; Potter, S. B.; O'Donoghue, D.; Siegmund, O. H. W.; Schellart, P.; Spark, M.; Welsh, B. Y.; Zietsman, E.

    2010-07-01

    While time resolved astronomical observations are not new, the extension of such studies to sub-second time resolution is and has resulted in the opening of a new observational frontier, High Time Resolution Astronomy (HTRA). HTRA studies are well suited to objects like compact binary stars (CVs and X-ray binaries) and pulsars, while asteroseismology of pulsating stars, occultations, transits and the study of transients, will all benefit from such HTRA studies. HTRA has been a SALT science driver from the outset and the first-light instruments, namely the UV-VIS imager, SALTICAM, and the multi-purpose Robert Stobie Spectrograph (RSS), both have high time resolution modes. These are described, together with some observational examples. We also discuss the commissioning observations with the photon counting Berkeley Visible Image Tube camera (BVIT) on SALT. Finally we describe the software tools, developed in Python, to reduce SALT time resolved observations.

  6. Time-resolved photoemission using attosecond streaking

    NASA Astrophysics Data System (ADS)

    Nagele, S.; Pazourek, R.; Wais, M.; Wachter, G.; Burgdörfer, J.

    2014-04-01

    We theoretically study time-resolved photoemission in atoms as probed by attosecond streaking. We review recent advances in the study of the photoelectric efect in the time domain and show that the experimentally accessible time shifts can be decomposed into distinct contributions that stem from the feld-free photoionization process itself and from probe-field induced corrections. We perform accurate quantum-mechanical as well as classical simulations of attosecond streaking for efective one-electron systems and determine all relevant contributions to the time delay with attosecond precision. In particular, we investigate the properties and limitations of attosecond streaking for the transition from short-ranged potentials (photodetachment) to long-ranged Coulomb potentials (photoionization). As an example for a more complex system, we study time-resolved photoionization for endohedral fullerenes A@C60 and discuss how streaking time shifts are modifed due to the interaction of the C60 cage with the probing infrared streaking field.

  7. Time-resolved optical spectroscopy of wood.

    PubMed

    D'Andrea, C; Farina, A; Comelli, D; Pifferi, A; Taroni, P; Valentini, G; Cubeddu, R; Zoia, L; Orlandi, M; Kienle, A

    2008-05-01

    We have proposed and experimentally demonstrated that picosecond time-resolved optical spectroscopy in the visible/near-infrared (NIR) region (700-1040 nm) is a useful technique for noninvasive characterization of wood. This technique has been demonstrated on both softwood and hardwood samples treated in different ways simulating the aging process suffered by waterlogged woods. In all the cases, alterations of absorption and scattering spectra were observed, revealing changes of chemical and structural composition.

  8. Time-resolved inverse Raman spectroscopy.

    PubMed

    Rahn, L A

    1982-02-01

    A technique for obtaining sensitive, highly reproducible, time-resolved inverse Raman measurements is reported. Experimental results are presented for the nitrogen vibrational Q branch at a pressure of 10 atm. For these measurements the signal, normalized to the pump-laser energy, exhibits fluctuations of 1.4% (rms) about the average of 500 measurements; these deviations are within a factor of 2 of the quantum noise limit.

  9. Assessment of the impact of oxidation processes on indoor air pollution using the new time-resolved INCA-Indoor model

    NASA Astrophysics Data System (ADS)

    Mendez, Maxence; Blond, Nadège; Blondeau, Patrice; Schoemaecker, Coralie; Hauglustaine, Didier A.

    2015-12-01

    INCA-Indoor, a new indoor air quality (IAQ) model, has been developed to simulate the concentrations of volatile organic compounds (VOC) and oxidants considering indoor air specific processes such as: emission, ventilation, surface interactions (sorption, deposition, uptake). Based on the detailed version of SAPRC-07 chemical mechanism, INCA-Indoor is able to analyze the contribution of the production and loss pathways of key chemical species (VOCs, oxidants, radical species). The potential of this model has been tested through three complementary analyses: a comparison with the most detailed IAQ model found in the literature, focusing on oxidant species; realistic scenarios covering a large range of conditions, involving variable OH sources like HONO; and the investigation of alkenes ozonolysis under a large range of indoor conditions that can increase OH and HO2 concentrations. Simulations have been run changing nitrous acid (HONO) concentrations, NOx levels, photolysis rates and ventilation rates, showing that HONO can be the main source of indoor OH. Cleaning events using products containing D-limonene have been simulated at different periods of the day. These scenarios show that HOX concentrations can significantly increase in specific conditions. An assessment of the impact of indoor chemistry on the potential formation of secondary species such as formaldehyde (HCHO) and acetaldehyde (CH3CHO) has been carried out under various room configuration scenarios and a study of the HOx budget for different realistic scenarios has been performed. It has been shown that, under the simulation conditions, formaldehyde can be affected by oxidant concentrations via chemical production which can account for more than 10% of the total production, representing 6.5 ppb/h. On the other hand, acetaldehyde production is affected more by oxidation processes. When the photolysis rates are high, chemical processes are responsible for about 50% of the total production of

  10. Development of an Optimum Tracer Set for Apportioning Emissions of Individual Power Plants Using Highly Time-Resolved Measurements and Advanced Receptor Modeling

    SciTech Connect

    John Ondov; Gregory Beachley

    2007-07-05

    In previous studies, 11 elements (Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Se, and Zn) were determined in 30-minute aerosol samples collected with the University of Maryland Semicontinuous Elements in Aerosol Sampler (SEAS; Kidwell and Ondov, 2001, 2004; SEAS-II) in several locations in which air quality is influenced by emissions from coal- or oil-fired power plants. At this time resolution, plumes from stationary high temperature combustion sources are readily detected as large excursions in ambient concentrations of elements emitted by these sources (Pancras et al. ). Moreover, the time-series data contain intrinsic information on the lateral diffusion of the plume (e.g., {sigma}{sub y}), which Park et al. (2005 and 2006) have exploited in their Pseudo-Deterministic Receptor Model (PDRM), to calculate emission rates of SO{sub 2} and 11 elements (mentioned above) from four individual coal- and oil-fired power plants in the Tampa Bay area. In the current project, we proposed that the resolving power of source apportionment methods might be improved by expanding the set of maker species and that there exist some optimum set of marker species that could be used. The ultimate goal was to determine the utility of using additional elements to better identify and isolate contributions of individual power plants to ambient levels of PM and its constituents. And, having achieved better resolution, achieve, also, better emission rate estimates. In this study, we optimized sample preparation and instrumental protocols for simultaneous analysis of 28 elements in dilute slurry samples collected with the SEAS with a new state-of-the-art Thermo-Systems, Inc., X-series II, Inductively Coupled Plasma Mass Spectroscopy (ICP-MS), and reanalyzed the samples previously collected in Tampa during the modeling period studied by Park et al. (2005) in which emission rates from four coal- and oil-fired power plants affected air quality at the sampling site. In the original model, Park et al

  11. Time-Resolved Measurements in Optoelectronic Microbioanalysis

    NASA Technical Reports Server (NTRS)

    Bearman, Gregory; Kossakovski, Dmitri

    2003-01-01

    A report presents discussion of time-resolved measurements in optoelectronic microbioanalysis. Proposed microbioanalytical laboratory-on-a-chip devices for detection of microbes and toxic chemicals would include optoelectronic sensors and associated electronic circuits that would look for fluorescence or phosphorescence signatures of multiple hazardous biomolecules in order to detect which ones were present in a given situation. The emphasis in the instant report is on gating an active-pixel sensor in the time domain, instead of filtering light in the wavelength domain, to prevent the sensor from responding to a laser pulse used to excite fluorescence or phosphorescence while enabling the sensor to respond to the decaying fluorescence or phosphorescence signal that follows the laser pulse. The active-pixel sensor would be turned on after the laser pulse and would be used to either integrate the fluorescence or phosphorescence signal over several lifetimes and many excitation pulses or else take time-resolved measurements of the fluorescence or phosphorescence. The report also discusses issues of multiplexing and of using time-resolved measurements of fluorophores with known different fluorescence lifetimes to distinguish among them.

  12. Space-time resolved simulation of femtosecond nonlinear light-matter interactions using a holistic quantum atomic model: application to near-threshold harmonics.

    PubMed

    Kolesik, M; Wright, E M; Andreasen, J; Brown, J M; Carlson, D R; Jones, R J

    2012-07-02

    We introduce a new computational approach for femtosecond pulse propagation in the transparency region of gases that permits full resolution in three space dimensions plus time while fully incorporating quantum coherent effects such as high-harmonic generation and strong-field ionization in a holistic fashion. This is achieved by utilizing a one-dimensional model atom with a delta-function potential which allows for a closed-form solution for the nonlinear optical response due to ground-state to continuum transitions. It side-steps evaluation of the wave function, and offers more than one hundred-fold reduction in computation time in comparison to direct solution of the atomic Schrödinger equation. To illustrate the capability of our new computational approach, we apply it to the example of near-threshold harmonic generation in Xenon, and we also present a qualitative comparison between our model and results from an in-house experiment on extreme ultraviolet generation in a femtosecond enhancement cavity.

  13. Time-resolved Emission from Bright Hot Pixels of an Active Region Observed in the EUV Band with SDO/AIA and Multi-stranded Loop Modeling

    NASA Astrophysics Data System (ADS)

    Tajfirouze, E.; Reale, F.; Petralia, A.; Testa, P.

    2016-01-01

    Evidence of small amounts of very hot plasma has been found in active regions and might be an indication of impulsive heating released at spatial scales smaller than the cross-section of a single loop. We investigate the heating and substructure of coronal loops in the core of one such active region by analyzing the light curves in the smallest resolution elements of solar observations in two EUV channels (94 and 335 Å) from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. We model the evolution of a bundle of strands heated by a storm of nanoflares by means of a hydrodynamic 0D loop model (EBTEL). The light curves obtained from a random combination of those of single strands are compared to the observed light curves either in a single pixel or in a row of pixels, simultaneously in the two channels, and using two independent methods: an artificial intelligent system (Probabilistic Neural Network) and a simple cross-correlation technique. We explore the space of the parameters to constrain the distribution of the heat pulses, their duration, their spatial size, and, as a feedback on the data, their signatures on the light curves. From both methods the best agreement is obtained for a relatively large population of events (1000) with a short duration (less than 1 minute) and a relatively shallow distribution (power law with index 1.5) in a limited energy range (1.5 decades). The feedback on the data indicates that bumps in the light curves, especially in the 94 Å channel, are signatures of a heating excess that occurred a few minutes before.

  14. TIME-RESOLVED EMISSION FROM BRIGHT HOT PIXELS OF AN ACTIVE REGION OBSERVED IN THE EUV BAND WITH SDO/AIA AND MULTI-STRANDED LOOP MODELING

    SciTech Connect

    Tajfirouze, E.; Reale, F.; Petralia, A.; Testa, P.

    2016-01-01

    Evidence of small amounts of very hot plasma has been found in active regions and might be an indication of impulsive heating released at spatial scales smaller than the cross-section of a single loop. We investigate the heating and substructure of coronal loops in the core of one such active region by analyzing the light curves in the smallest resolution elements of solar observations in two EUV channels (94 and 335 Å) from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. We model the evolution of a bundle of strands heated by a storm of nanoflares by means of a hydrodynamic 0D loop model (EBTEL). The light curves obtained from a random combination of those of single strands are compared to the observed light curves either in a single pixel or in a row of pixels, simultaneously in the two channels, and using two independent methods: an artificial intelligent system (Probabilistic Neural Network) and a simple cross-correlation technique. We explore the space of the parameters to constrain the distribution of the heat pulses, their duration, their spatial size, and, as a feedback on the data, their signatures on the light curves. From both methods the best agreement is obtained for a relatively large population of events (1000) with a short duration (less than 1 minute) and a relatively shallow distribution (power law with index 1.5) in a limited energy range (1.5 decades). The feedback on the data indicates that bumps in the light curves, especially in the 94 Å channel, are signatures of a heating excess that occurred a few minutes before.

  15. Oligomerization of epidermal growth factor receptors on A431 cells studied by time-resolved fluorescence imaging microscopy. A stereochemical model for tyrosine kinase receptor activation

    PubMed Central

    1995-01-01

    The aggregation states of the epidermal growth factor receptor (EGFR) on single A431 human epidermoid carcinoma cells were assessed with two new techniques for determining fluorescence resonance energy transfer: donor photobleaching fluorescence resonance energy transfer (pbFRET) microscopy and fluorescence lifetime imaging microscopy (FLIM). Fluorescein-(donor) and rhodamine-(acceptor) labeled EGF were bound to the cells and the extent of oligomerization was monitored by the spatially resolved FRET efficiency as a function of the donor/acceptor ratio and treatment conditions. An average FRET efficiency of 5% was determined after a low temperature (4 degrees C) incubation with the fluorescent EGF analogs for 40 min. A subsequent elevation of the temperature for 5 min caused a substantial increase of the average FRET efficiency to 14% at 20 degrees C and 31% at 37 degrees C. In the context of a two-state (monomer/dimer) model for the EGFR, these FRET efficiencies were consistent with minimal average receptor dimerizations of 13, 36, and 69% at 4, 20, and 37 degrees C, respectively. A431 cells were pretreated with the monoclonal antibody mAb 2E9 that specifically blocks EGF binding to the predominant population of low affinity EGFR (15). The average FRET efficiency increased dramatically to 28% at 4 degrees C, indicative of a minimal receptor dimerization of 65% for the subpopulation of high affinity receptors. These results are in accordance with prior studies indicating that binding of EGF leads to a fast and temperature- dependent microclustering of EGFR, but suggest in addition that the high affinity functional subclass of receptors on quiescent A431 cells are present in a predimerized or oligomerized state. We propose that the transmission of the external ligand-binding signal to the cytoplasmic domain is effected by a concerted relative rotational rearrangement of the monomeric units comprising the dimeric receptor, thereby potentiating a mutual activation of

  16. Time-resolved transcriptome analysis and lipid pathway reconstruction of the oleaginous green microalga Monoraphidium neglectum reveal a model for triacylglycerol and lipid hyperaccumulation.

    PubMed

    Jaeger, Daniel; Winkler, Anika; Mussgnug, Jan H; Kalinowski, Jörn; Goesmann, Alexander; Kruse, Olaf

    2017-01-01

    Oleaginous microalgae are promising production hosts for the sustainable generation of lipid-based bioproducts and as bioenergy carriers such as biodiesel. Transcriptomics of the lipid accumulation phase, triggered efficiently by nitrogen starvation, is a valuable approach for the identification of gene targets for metabolic engineering. An explorative analysis of the detailed transcriptional response to different stages of nitrogen availability was performed in the oleaginous green alga Monoraphidium neglectum. Transcript data were correlated with metabolic data for cellular contents of starch and of different lipid fractions. A pronounced transcriptional down-regulation of photosynthesis became apparent in response to nitrogen starvation, whereas glucose catabolism was found to be up-regulated. An in-depth reconstruction and analysis of the pathways for glycerolipid, central carbon, and starch metabolism revealed that distinct transcriptional changes were generally found only for specific steps within a metabolic pathway. In addition to pathway analyses, the transcript data were also used to refine the current genome annotation. The transcriptome data were integrated into a database and complemented with data for other microalgae which were also subjected to nitrogen starvation. It is available at https://tdbmn.cebitec.uni-bielefeld.de. Based on the transcriptional responses to different stages of nitrogen availability, a model for triacylglycerol and lipid hyperaccumulation is proposed, which involves transcriptional induction of thioesterases, differential regulation of lipases, and a re-routing of the central carbon metabolism. Over-expression of distinct thioesterases was identified to be a potential strategy to increase the oleaginous phenotype of M. neglectum, and furthermore specific lipases were identified as potential targets for future metabolic engineering approaches.

  17. Evaluation of time-resolved multi-distance methods to retrieve absorption and reduced scattering coefficients of adult heads in vivo: Optical parameters dependences on geometrical structures of the models used to calculate reflectance

    NASA Astrophysics Data System (ADS)

    Tanifuji, T.

    2016-03-01

    Time-resolved multi-distance measurements are studied to retrieve absorption and reduced scattering coefficients of adult heads, which have enough depth sensitivity to determine the optical parameters in superficial tissues and brain separately. Measurements were performed by putting the injection and collection fibers on the left semi-sphere of the forehead, with the injection fiber placed toward the temporal region, and by moving the collection fiber between 10 and 60 mm from the central sulcus. It became clear that optical parameters of the forehead at all collection fibers were reasonably determined by selecting the appropriate visibility length of the geometrical head models, which is related to head surface curvature at each position.

  18. The Keilson and Storer 3-dimensional (KS-3D) line shape model: applications to optical diagnostic in combustion media

    SciTech Connect

    Joubert, Pierre

    2008-10-22

    High-resolution infrared and Raman spectroscopies require refine spectral line shape model to account for all observed features. For instance, for gaseous mixtures of light molecules with heavy perturbers, drastic changes arise particularly in the collision regime, resulting from the inhomogeneous effects due to the radiator speed-dependence of the collisional line broadening and line shifting parameters. Following our previous work concerning the collision regime, we have developed a new line shape modelization called the Keilson and Storer 3-dimensional line shape model to lower densities, when the Doppler contribution, and the collisional confinement narrowing can be no longer neglected. The consequences for optical diagnostics, particularly for H{sub 2}-N{sub 2} mixtures with high pressure and high temperature are presented. The effects of collisional relaxation on the spectral line shapes are discussed.

  19. Analytical study of twin-jet shielding development of a 3-dimensional model

    NASA Technical Reports Server (NTRS)

    Gerhold, C. H.

    1980-01-01

    The solution for a point source impinging on a cylinder of heated flow is presented. The indefinite integral is solved approximately using a saddle of point method. Comparison of the three-dimensional model to a previously obtained two-dimensional model of twin jet noise indicate the the approximate solution of the integral is valid. The model was analyzed to differentiate among the mechanims of shielding. Zone in which diffraction and transmission dominate are identified. The model was found to compare to experimental shielding results.

  20. Time Resolved Studies Of Adsorbed Species

    NASA Astrophysics Data System (ADS)

    Howard, J.; Nicol, J. M.

    1985-12-01

    A time-resolved Fourier transform IR study of ethyne adsorbed on ZnNaA zeolite yields results very different from those reported for related systems. Initially two species (A and B) are formed by the interaction of C2H2 with the cations. Whereas species A (π-bonded C2H2) was found to be removed immediately on evacuation, species B (probably Zn-acetylide) was not fully removed after 60 mins evacuation. In the presence of the gas phase, bands due to Species A decreased slowly in intensity as new bands due to adsorbed ethanal were observed.

  1. Fast time variations of supernova neutrino signals from 3-dimensional models

    DOE PAGES

    Lund, Tina; Wongwathanarat, Annop; Janka, Hans -Thomas; ...

    2012-11-19

    Here, we study supernova neutrino flux variations in the IceCube detector, using 3D models based on a simplified neutrino transport scheme. The hemispherically integrated neutrino emission shows significantly smaller variations compared with our previous study of 2D models, largely because of the reduced activity of the standing accretion shock instability in this set of 3D models which we interpret as a pessimistic extreme. For the studied cases, intrinsic flux variations up to about 100 Hz frequencies could still be detected in a supernova closer than about 2 kpc.

  2. Visualization of the 3-dimensional flow around a model with the aid of a laser knife

    NASA Technical Reports Server (NTRS)

    Borovoy, V. Y.; Ivanov, V. V.; Orlov, A. A.; Kharchenko, V. N.

    1984-01-01

    A method for visualizing the three-dimensional flow around models of various shapes in a wind tunnel at a Mach number of 5 is described. A laser provides a planar light flux such that any plane through the model can be selectively illuminated. The shape of shock waves and separation regions is then determined by the intensity of light scattered by soot particles in the flow.

  3. Mandibular reconstruction using plates prebent to fit rapid prototyping 3-dimensional printing models ameliorates contour deformity.

    PubMed

    Azuma, Masaki; Yanagawa, Toru; Ishibashi-Kanno, Naomi; Uchida, Fumihiko; Ito, Takaaki; Yamagata, Kenji; Hasegawa, Shogo; Sasaki, Kaoru; Adachi, Koji; Tabuchi, Katsuhiko; Sekido, Mitsuru; Bukawa, Hiroki

    2014-10-23

    Recently, medical rapid prototyping (MRP) models, fabricated with computer-aided design and computer-aided manufacture (CAD/CAM) techniques, have been applied to reconstructive surgery in the treatment of head and neck cancers. Here, we tested the use of preoperatively manufactured reconstruction plates, which were produced using MRP models. The clinical efficacy and esthetic outcome of using these products in mandibular reconstruction was evaluated. A series of 28 patients with malignant oral tumors underwent unilateral segmental resection of the mandible and simultaneous mandibular reconstruction. Twelve patients were treated with prebent reconstruction plates that were molded to MRP mandibular models designed with CAD/CAM techniques and fabricated on a combined powder bed and inkjet head three-dimensional printer. The remaining 16 patients were treated using conventional reconstruction methods. The surgical and esthetic outcomes of the two groups were compared by imaging analysis using post-operative panoramic tomography. The mandibular symmetry in patients receiving the MRP-model-based prebent plates was significantly better than that in patients receiving conventional reconstructive surgery. Patients with head and neck cancer undergoing reconstructive surgery using a prebent reconstruction plate fabricated according to an MRP mandibular model showed improved mandibular contour compared to patients undergoing conventional mandibular reconstruction. Thus, use of this new technology for mandibular reconstruction results in an improved esthetic outcome with the potential for improved quality of life for patients.

  4. Remanent magnetization and 3-dimensional density model of the Kentucky anomaly region

    NASA Technical Reports Server (NTRS)

    Mayhew, M. A.; Estes, R. H.; Myers, D. M.

    1984-01-01

    A three-dimensional model of the Kentucky body was developed to fit surface gravity and long wavelength aeromagnetic data. Magnetization and density parameters for the model are much like those of Mayhew et al (1982). The magnetic anomaly due to the model at satellite altitude is shown to be much too small by itself to account for the anomaly measured by Magsat. It is demonstrated that the source region for the satellite anomaly is considerably more extensive than the Kentucky body sensu stricto. The extended source region is modeled first using prismatic model sources and then using dipole array sources. Magnetization directions for the source region found by inversion of various combinations of scalar and vector data are found to be close to the main field direction, implying the lack of a strong remanent component. It is shown by simulation that in a case (such as this) where the geometry of the source is known, if a strong remanent component is present its direction is readily detectable, but by scalar data as readily as vector data.

  5. A simple, analytic 3-dimensional downburst model based on boundary layer stagnation flow

    NASA Technical Reports Server (NTRS)

    Oseguera, Rosa M.; Bowles, Roland L.

    1988-01-01

    A simple downburst model is developed for use in batch and real-time piloted simulation studies of guidance strategies for terminal area transport aircraft operations in wind shear conditions. The model represents an axisymmetric stagnation point flow, based on velocity profiles from the Terminal Area Simulation System (TASS) model developed by Proctor and satisfies the mass continuity equation in cylindrical coordinates. Altitude dependence, including boundary layer effects near the ground, closely matches real-world measurements, as do the increase, peak, and decay of outflow and downflow with increasing distance from the downburst center. Equations for horizontal and vertical winds were derived, and found to be infinitely differentiable, with no singular points existent in the flow field. In addition, a simple relationship exists among the ratio of maximum horizontal to vertical velocities, the downdraft radius, depth of outflow, and altitude of maximum outflow. In use, a microburst can be modeled by specifying four characteristic parameters, velocity components in the x, y and z directions, and the corresponding nine partial derivatives are obtained easily from the velocity equations.

  6. Accretion Onto Supermassive Black Holes: Observational Signals from 3-Dimensional Disk Models

    NASA Technical Reports Server (NTRS)

    Bromley, Benjamin C.; Miller, Warner A.

    2003-01-01

    Our project was to model accretion flows onto supermassive black holes which reside in the centers of many galaxies. In this report we summarize the results which we obtained with the support of our NASA ATP grant. The scientific results associated with the grant are given in approximately chronological order. We also provide a list of references which acknowledge funding from this grant.

  7. Accretion Onto Supermassive Black Holes: Observational Signals from 3-Dimensional Disk Models

    NASA Technical Reports Server (NTRS)

    Bromley, Benjamin C.; Miller, Warner A.

    2003-01-01

    Our project was to model accretion flows onto supermassive black holes which reside in the centers of many galaxies. In this report we summarize the results which we obtained with the support of our NASA ATP grant. The scientific results associated with the grant are given in approximately chronological order. We also provide a list of references which acknowledge funding from this grant.

  8. Time-resolved RNA SHAPE chemistry.

    PubMed

    Mortimer, Stefanie A; Weeks, Kevin M

    2008-12-03

    Selective 2'-hydroxyl acylation analyzed by primer extension (SHAPE) chemistry yields quantitative RNA secondary and tertiary structure information at single nucleotide resolution. SHAPE takes advantage of the discovery that the nucleophilic reactivity of the ribose 2'-hydroxyl group is modulated by local nucleotide flexibility in the RNA backbone. Flexible nucleotides are reactive toward hydroxyl-selective electrophiles, whereas constrained nucleotides are unreactive. Initial versions of SHAPE chemistry, which employ isatoic anhydride derivatives that react on the minute time scale, are emerging as the ideal technology for monitoring equilibrium structures of RNA in a wide variety of biological environments. Here, we extend SHAPE chemistry to a benzoyl cyanide scaffold to make possible facile time-resolved kinetic studies of RNA in approximately 1 s snapshots. We then use SHAPE chemistry to follow the time-dependent folding of an RNase P specificity domain RNA. Tertiary interactions form in two distinct steps with local tertiary contacts forming an order of magnitude faster than long-range interactions. Rate-determining tertiary folding requires minutes despite that no non-native interactions must be disrupted to form the native structure. Instead, overall folding is limited by simultaneous formation of interactions approximately 55 A distant in the RNA. Time-resolved SHAPE holds broad potential for understanding structural biogenesis and the conformational interconversions essential to the functions of complex RNA molecules at single nucleotide resolution.

  9. Estimation of Nasal Tip Support Using Computer-Aided Design and 3-Dimensional Printed Models

    PubMed Central

    Gray, Eric; Maducdoc, Marlon; Manuel, Cyrus; Wong, Brian J. F.

    2016-01-01

    IMPORTANCE Palpation of the nasal tip is an essential component of the preoperative rhinoplasty examination. Measuring tip support is challenging, and the forces that correspond to ideal tip support are unknown. OBJECTIVE To identify the integrated reaction force and the minimum and ideal mechanical properties associated with nasal tip support. DESIGN, SETTING, AND PARTICIPANTS Three-dimensional (3-D) printed anatomic silicone nasal models were created using a computed tomographic scan and computer-aided design software. From this model, 3-D printing and casting methods were used to create 5 anatomically correct nasal models of varying constitutive Young moduli (0.042, 0.086, 0.098, 0.252, and 0.302 MPa) from silicone. Thirty rhinoplasty surgeons who attended a regional rhinoplasty course evaluated the reaction force (nasal tip recoil) of each model by palpation and selected the model that satisfied their requirements for minimum and ideal tip support. Data were collected from May 3 to 4, 2014. RESULTS Of the 30 respondents, 4 surgeons had been in practice for 1 to 5 years; 9 surgeons, 6 to 15 years; 7 surgeons, 16 to 25 years; and 10 surgeons, 26 or more years. Seventeen surgeons considered themselves in the advanced to expert skill competency levels. Logistic regression estimated the minimum threshold for the Young moduli for adequate and ideal tip support to be 0.096 and 0.154 MPa, respectively. Logistic regression estimated the thresholds for the reaction force associated with the absolute minimum and ideal requirements for good tip recoil to be 0.26 to 4.74 N and 0.37 to 7.19 N during 1- to 8-mm displacement, respectively. CONCLUSIONS AND RELEVANCE This study presents a method to estimate clinically relevant nasal tip reaction forces, which serve as a proxy for nasal tip support. This information will become increasingly important in computational modeling of nasal tip mechanics and ultimately will enhance surgical planning for rhinoplasty. LEVEL OF EVIDENCE

  10. 3-dimensional spatially organized PEG-based hydrogels for an aortic valve co-culture model

    PubMed Central

    Puperi, Daniel S.; Balaoing, Liezl R.; O’Connell, Ronan W.; West, Jennifer L.; Grande-Allen, K. Jane

    2015-01-01

    Physiologically relevant in vitro models are needed to study disease progression and to develop and screen potential therapeutic interventions for disease. Heart valve disease, in particular, has no early intervention or non-invasive treatment because there is a lack of understanding the cellular mechanisms which lead to disease. Here, we establish a novel, customizable synthetic hydrogel platform that can be used to study cell-cell interactions and the factors which contribute to valve disease. Spatially localized cell adhesive ligands bound in the scaffold promote cell growth and organization of valve interstitial cells and valve endothelial cells in 3D co-culture. Both cell types maintained phenotypes, homeostatic functions, and produced zonally localized extracellular matrix. This model extends the capabilities of in vitro research by providing a platform to perform direct contact co-culture with cells in their physiologically relevant spatial arrangement. PMID:26241755

  11. A simple and efficient quasi 3-dimensional viscoelastic model and software for simulation of tapping-mode atomic force microscopy

    SciTech Connect

    Solares, Santiago D.

    2015-11-26

    This study introduces a quasi-3-dimensional (Q3D) viscoelastic model and software tool for use in atomic force microscopy (AFM) simulations. The model is based on a 2-dimensional array of standard linear solid (SLS) model elements. The well-known 1-dimensional SLS model is a textbook example in viscoelastic theory but is relatively new in AFM simulation. It is the simplest model that offers a qualitatively correct description of the most fundamental viscoelastic behaviors, namely stress relaxation and creep. However, this simple model does not reflect the correct curvature in the repulsive portion of the force curve, so its application in the quantitative interpretation of AFM experiments is relatively limited. In the proposed Q3D model the use of an array of SLS elements leads to force curves that have the typical upward curvature in the repulsive region, while still offering a very low computational cost. Furthermore, the use of a multidimensional model allows for the study of AFM tips having non-ideal geometries, which can be extremely useful in practice. Examples of typical force curves are provided for single- and multifrequency tappingmode imaging, for both of which the force curves exhibit the expected features. Lastly, a software tool to simulate amplitude and phase spectroscopy curves is provided, which can be easily modified to implement other controls schemes in order to aid in the interpretation of AFM experiments.

  12. A simple and efficient quasi 3-dimensional viscoelastic model and software for simulation of tapping-mode atomic force microscopy.

    PubMed

    Solares, Santiago D

    2015-01-01

    This paper introduces a quasi-3-dimensional (Q3D) viscoelastic model and software tool for use in atomic force microscopy (AFM) simulations. The model is based on a 2-dimensional array of standard linear solid (SLS) model elements. The well-known 1-dimensional SLS model is a textbook example in viscoelastic theory but is relatively new in AFM simulation. It is the simplest model that offers a qualitatively correct description of the most fundamental viscoelastic behaviors, namely stress relaxation and creep. However, this simple model does not reflect the correct curvature in the repulsive portion of the force curve, so its application in the quantitative interpretation of AFM experiments is relatively limited. In the proposed Q3D model the use of an array of SLS elements leads to force curves that have the typical upward curvature in the repulsive region, while still offering a very low computational cost. Furthermore, the use of a multidimensional model allows for the study of AFM tips having non-ideal geometries, which can be extremely useful in practice. Examples of typical force curves are provided for single- and multifrequency tapping-mode imaging, for both of which the force curves exhibit the expected features. Finally, a software tool to simulate amplitude and phase spectroscopy curves is provided, which can be easily modified to implement other controls schemes in order to aid in the interpretation of AFM experiments.

  13. A simple and efficient quasi 3-dimensional viscoelastic model and software for simulation of tapping-mode atomic force microscopy

    DOE PAGES

    Solares, Santiago D.

    2015-11-26

    This study introduces a quasi-3-dimensional (Q3D) viscoelastic model and software tool for use in atomic force microscopy (AFM) simulations. The model is based on a 2-dimensional array of standard linear solid (SLS) model elements. The well-known 1-dimensional SLS model is a textbook example in viscoelastic theory but is relatively new in AFM simulation. It is the simplest model that offers a qualitatively correct description of the most fundamental viscoelastic behaviors, namely stress relaxation and creep. However, this simple model does not reflect the correct curvature in the repulsive portion of the force curve, so its application in the quantitative interpretationmore » of AFM experiments is relatively limited. In the proposed Q3D model the use of an array of SLS elements leads to force curves that have the typical upward curvature in the repulsive region, while still offering a very low computational cost. Furthermore, the use of a multidimensional model allows for the study of AFM tips having non-ideal geometries, which can be extremely useful in practice. Examples of typical force curves are provided for single- and multifrequency tappingmode imaging, for both of which the force curves exhibit the expected features. Lastly, a software tool to simulate amplitude and phase spectroscopy curves is provided, which can be easily modified to implement other controls schemes in order to aid in the interpretation of AFM experiments.« less

  14. 3-dimensional numerical modeling of an industrial radio frequency heating system using finite elements.

    PubMed

    Chan, T V Chow Ting; Tang, J; Younce, F

    2004-01-01

    This paper presents a new, yet simple and effective approach to modeling industrial Radio Frequency heating systems, using the wave equation applied in three dimensions instead of the conventional electrostatics method. The central idea is that the tank oscillatory circuit is excited using an external source. This then excites the applicator circuit which is then used to heat or dry the processed load. Good agreement was obtained between the experimental and numerical data, namely the S11-parameter, phase, and heating patterns for different sized loads and positions.

  15. Goddard Institute for Space Studies (GISS) 3-Dimensional (3-D) Global Tracer Transport Model

    DOE Data Explorer

    Fung, I.

    1993-01-01

    This directory contains the input files used in simulations of atmospheric CO2 using the GISS 3-D global tracer transport model. The directory contains 16 files including a help file (CO2FUNG.HLP), 12 files containing monthly exchanges with vegetation and soils (CO2VEG.JAN . . . DEC), 1 file containing releases of CO2 from fossil fuel burning (CO2FOS.MRL), 1 file containing releases of CO2 from land transformations (CO2DEF.HOU), and 1 file containing the patterns of CO2 exchange with the oceans (CO2OCN.TAK).

  16. 3-DIMENSIONAL Geometric Survey and Structural Modelling of the Dome of Pisa Cathedral

    NASA Astrophysics Data System (ADS)

    Aita, D.; Barsotti, R.; Bennati, S.; Caroti, G.; Piemonte, A.

    2017-02-01

    This paper aims to illustrate the preliminary results of a research project on the dome of Pisa Cathedral (Italy). The final objective of the present research is to achieve a deep understanding of the structural behaviour of the dome, through a detailed knowledge of its geometry and constituent materials, and by taking into account historical and architectural aspects as well. A reliable survey of the dome is the essential starting point for any further investigation and adequate structural modelling. Examination of the status quo on the surveys of the Cathedral dome shows that a detailed survey suitable for structural analysis is in fact lacking. For this reason, high-density and high-precision surveys have been planned, by considering that a different survey output is needed, according both to the type of structural model chosen and purposes to be achieved. Thus, both range-based (laser scanning) and image-based (3D Photogrammetry) survey methodologies have been used. This contribution introduces the first results concerning the shape of the dome derived from surveys. Furthermore, a comparison is made between such survey outputs and those available in the literature.

  17. Time-resolved studies of individual molecular rotors.

    PubMed

    Jewell, April D; Tierney, Heather L; Baber, Ashleigh E; Iski, Erin V; Laha, Michael M; Sykes, E Charles H

    2010-07-07

    Thioether molecular rotors show great promise as nanoscale models for exploring the fundamental limits of thermally and electrically driven molecular rotation. By using time-resolved measurements which increase the time resolution of the scanning tunneling microscope we were able to record the dynamics of individual thioether molecular rotors as a function of surface structure, rotor chemistry, thermal energy and electrical excitation. Our results demonstrate that the local surface structure can have a dramatic influence on the energy landscape that the molecular rotors experience. In terms of rotor structure, altering the length of the rotor's alkyl tails allowed the origin of the barrier to rotation to be more fully understood. Finally, time-resolved measurement of electrically excited rotation revealed that vibrational excitation of a C-H bond in the rotor's alkyl tail is an efficient channel with which to excite rotation, and that the excitation is a one-electron process. © 2010 IOP Publishing Ltd

  18. Evaluation of 3-Dimensional Superimposition Techniques on Various Skeletal Structures of the Head Using Surface Models

    PubMed Central

    Pazera, Pawel; Zorkun, Berna; Katsaros, Christos; Ludwig, Björn

    2015-01-01

    Objectives To test the applicability, accuracy, precision, and reproducibility of various 3D superimposition techniques for radiographic data, transformed to triangulated surface data. Methods Five superimposition techniques (3P: three-point registration; AC: anterior cranial base; AC + F: anterior cranial base + foramen magnum; BZ: both zygomatic arches; 1Z: one zygomatic arch) were tested using eight pairs of pre-existing CT data (pre- and post-treatment). These were obtained from non-growing orthodontic patients treated with rapid maxillary expansion. All datasets were superimposed by three operators independently, who repeated the whole procedure one month later. Accuracy was assessed by the distance (D) between superimposed datasets on three form-stable anatomical areas, located on the anterior cranial base and the foramen magnum. Precision and reproducibility were assessed using the distances between models at four specific landmarks. Non parametric multivariate models and Bland-Altman difference plots were used for analyses. Results There was no difference among operators or between time points on the accuracy of each superimposition technique (p>0.05). The AC + F technique was the most accurate (D<0.17 mm), as expected, followed by AC and BZ superimpositions that presented similar level of accuracy (D<0.5 mm). 3P and 1Z were the least accurate superimpositions (0.790.05), the detected structural changes differed significantly between different techniques (p<0.05). Bland-Altman difference plots showed that BZ superimposition was comparable to AC, though it presented slightly higher random error. Conclusions Superimposition of 3D datasets using surface models created from voxel data can provide accurate, precise, and reproducible results, offering also high efficiency and increased post-processing capabilities. In

  19. Longitudinal evaluation of dental arch asymmetry in Class II subdivision malocclusion with 3-dimensional digital models.

    PubMed

    Veli, Ilknur; Yuksel, Burcin; Uysal, Tancan

    2014-06-01

    Class II subdivision malocclusions with their asymmetric occlusal relationships often pose treatment difficulties. The aim of this study was to evaluate the longitudinal changes of dental arch asymmetry in untreated subjects with Class II subdivision malocclusion. From 706 files from the University of Michigan Growth Study, longitudinal records of 17 untreated subjects with Class II subdivision malocclusion were included this study. Dental arch changes at 3 consecutive longitudinal intervals, defined by the cervical vertebral maturation method, were analyzed on digital dental models. The average ages of the subjects were 12.4, 15.1, and 19.1 years at the 3 time periods, respectively. Maxillary and mandibular reference lines were constructed and used for the intra-arch asymmetry measurements. The Friedman test and analysis of variance with repeated measures were used to determine dental arch asymmetries at the P <0.05 level. All subjects were found to have a type 1 Class II subdivision malocclusion characterized by distal positioning of the mandibular first molar on the Class II side. No statistically significant intra-arch asymmetry changes were found for the maxillary and mandibular dental arches in any time period. Between the baseline and the final follow-up, the data indicated decreases in maxillary and mandibular intercanine arch widths and arch lengths symmetrically. The results of this study indicate that the dental arch asymmetry in patients with Class II subdivision malocclusions did not improve or worsen with growth. Copyright © 2014 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

  20. Reconstituted 3-dimensional human skin as a novel in vitro model for studies of carcinogenesis.

    PubMed

    Zhao, J F; Zhang, Y J; Kubilus, J; Jin, X H; Santella, R M; Athar, M; Wang, Z Y; Bickers, D R

    1999-01-08

    EpiDerm (MatTek Co., MA) is a reconstituted human skin equivalent which exhibits morphological and growth characteristics similar to human skin. This model has previously been utilized to evaluate the cytotoxicity and irritant potential of various cosmetic and household products. In this study, we show for the first time that EpiDerm can be used successfully to evaluate the genotoxicity of different types of known carcinogenic agents such as benzo[a]pyrene (BaP), ultraviolet B radiation (UVB), ultraviolet A radiation (UVA), and psoralen-ultraviolet A radiation (PUVA) at the molecular level. The topical application of 50 microg/cm2 BaP to EpiDerm resulted in the accumulation of BaP-DNA adducts and c-fos and p53 proteins as evidenced by immunohistochemical localization. Similarly, exposure to UVB (50 mJ/cm2) and UVA (2.5 J/cm2) enhanced the epidermal expression of c-fos and p53 proteins in the human skin equivalent. PUVA treatment of EpiDerm, however, resulted in the formation of both DNA-8-MOP adducts and augmented expression of c-fos and p53 proteins. Most of these changes reached a peak 8 h after the treatments except in the case of UVA where maximum changes in the expression of c-fos and p53 proteins were observed 24 h after treatment. These results are similar to those previously reported in human and murine skin following exposure to BaP, UVB, UVA, or PUVA indicating that human skin equivalents can be used as a convenient and cost-effective alternative to animal testing for assessing the genotoxicity and mechanism of action of mutagens/carcinogens in human skin. Copyright 1999 Academic Press.

  1. Global simulation of canopy scale sun-induced chlorophyll fluorescence with a 3 dimensional radiative transfer model

    NASA Astrophysics Data System (ADS)

    Kobayashi, H.; Yang, W.; Ichii, K.

    2015-12-01

    Global simulation of canopy scale sun-induced chlorophyll fluorescence with a 3 dimensional radiative transfer modelHideki Kobayashi, Wei Yang, and Kazuhito IchiiDepartment of Environmental Geochemical Cycle Research, Japan Agency for Marine-Earth Science and Technology3173-25, Showa-machi, Kanazawa-ku, Yokohama, Japan.Plant canopy scale sun-induced chlorophyll fluorescence (SIF) can be observed from satellites, such as Greenhouse gases Observation Satellite (GOSAT), Orbiting Carbon Observatory-2 (OCO-2), and Global Ozone Monitoring Experiment-2 (GOME-2), using Fraunhofer lines in the near infrared spectral domain [1]. SIF is used to infer photosynthetic capacity of plant canopy [2]. However, it is not well understoond how the leaf-level SIF emission contributes to the top of canopy directional SIF because SIFs observed by the satellites use the near infrared spectral domain where the multiple scatterings among leaves are not negligible. It is necessary to quantify the fraction of emission for each satellite observation angle. Absorbed photosynthetically active radiation of sunlit leaves are 100 times higher than that of shaded leaves. Thus, contribution of sunlit and shaded leaves to canopy scale directional SIF emission should also be quantified. Here, we show the results of global simulation of SIF using a 3 dimensional radiative transfer simulation with MODIS atmospheric (aerosol optical thickness) and land (land cover and leaf area index) products and a forest landscape data sets prepared for each land cover category. The results are compared with satellite-based SIF (e.g. GOME-2) and the gross primary production empirically estimated by FLUXNET and remote sensing data.

  2. Evaluation of pharyngeal airway space changes after bimaxillary orthognathic surgery with a 3-dimensional simulation and modeling program.

    PubMed

    Gokce, Sila Mermut; Gorgulu, Serkan; Gokce, Hasan Suat; Bengi, Ali Osman; Karacayli, Umit; Ors, Fatih

    2014-10-01

    The aims of this study were to use 3-dimensional simulation and modeling programs to evaluate the effects of bimaxillary orthognathic surgical correction of Class III malocclusions on pharyngeal airway space volume, and to compare them with the changes in obstructive sleep apnea measurements from polysomnography. Twenty-five male patients (mean age, 21.6 years) with mandibular prognathism were treated with bilateral sagittal split osteotomy and LeFort I advancement. Polysomnography and computed tomography were performed before surgery and 1.4 ± 0.2 years after surgery. All computed tomography data were transferred to a computer, and the pharyngeal airway space was segmented using SimPlant OMS (Materialise Medical, Leuven, Belgium) programs. The pretreatment and posttreatment pharyngeal airway space determinants in volumetric, linear distance, and cross-sectional measurements, and polysomnography changes were compared with the paired samples t test. Pearson correlation was used to analyze the association between the computed tomography and polysomnography measurements. The results indicated that setback procedures produce anteroposterior narrowing of the pharyngeal airway space at the oropharyngeal and hypopharyngeal levels and the middle and inferior pharyngeal volumes (P <0.05). In contrast, advancement of the maxilla causes widening of the airway in the nasopharyngeal and retropalatal dimensions and increases the superior pharyngeal volume (P <0.05). Distinctively, bimaxillary orthognathic surgery induces significant increases in the total airway volume and the transverse dimensions of all airway areas (P <0.05). Significant correlations were found between the measurements on the computed tomography scans and crucial polysomnography parameters. Bimaxillary orthognathic surgery for correction of Class III malocclusion caused an increase of the total airway volume and improvement of polysomnography parameters. A proposed treatment plan can be modified

  3. Is a 3-Dimensional Stress Balance Ice-Stream Model Really Better Than a 2-Dimensional "Reduced Order" Ice-Stream Model?

    NASA Astrophysics Data System (ADS)

    Sergienko, O.; Macayeal, D. R.

    2007-12-01

    With growing observational awareness of numerous ice-stream processes occurring on short time and spatial scales, e.g., sub-ice-stream lake volume changes and grounding-line sediment wedge build-up, the question of how well models based on "reduced-order" dynamics can simulate ice-stream behavior becomes paramount. Reduced-order models of ice-streams are typically 2-dimensional, and capture only the largest-magnitude terms in the stress tensor (with other terms being constrained by various assumptions). In predicting the overall magnitude and large-scale pattern of ice-stream flow, the reduced-order models appear to be adequate. Efforts underway in the Glaciological Community to create 3-dimensional models of the "full" ice-stream stress balance, which relax the assumptions associated with reduced-order models, suggest that a cost/benefit analysis should be done to determine how likely these efforts will be fruitful. To assess the overall benefits of full 3-dimensional models in relation to the simpler 2-dimensional counterparts, we present model solutions of the full Stokes equations for ice-stream flow over a variety of basal perturbations (e.g., a sticky spot, a subglacial lake, a grounding line). We also present the solutions derived from reduced 2-dimensional models, and compare the two solutions to estimate effects of simplifications and neglected terms, as well as to advise on what circumstances 3-dimensional models are preferable to 2-dimensional models.

  4. A 3-dimensional human embryonic stem cell (hESC)-derived model to detect developmental neurotoxicity of nanoparticles.

    PubMed

    Hoelting, Lisa; Scheinhardt, Benjamin; Bondarenko, Olesja; Schildknecht, Stefan; Kapitza, Marion; Tanavde, Vivek; Tan, Betty; Lee, Qian Yi; Mecking, Stefan; Leist, Marcel; Kadereit, Suzanne

    2013-04-01

    Nanoparticles (NPs) have been shown to accumulate in organs, cross the blood-brain barrier and placenta, and have the potential to elicit developmental neurotoxicity (DNT). Here, we developed a human embryonic stem cell (hESC)-derived 3-dimensional (3-D) in vitro model that allows for testing of potential developmental neurotoxicants. Early central nervous system PAX6(+) precursor cells were generated from hESCs and differentiated further within 3-D structures. The 3-D model was characterized for neural marker expression revealing robust differentiation toward neuronal precursor cells, and gene expression profiling suggested a predominantly forebrain-like development. Altered neural gene expression due to exposure to non-cytotoxic concentrations of the known developmental neurotoxicant, methylmercury, indicated that the 3-D model could detect DNT. To test for specific toxicity of NPs, chemically inert polyethylene NPs (PE-NPs) were chosen. They penetrated deep into the 3-D structures and impacted gene expression at non-cytotoxic concentrations. NOTCH pathway genes such as HES5 and NOTCH1 were reduced in expression, as well as downstream neuronal precursor genes such as NEUROD1 and ASCL1. FOXG1, a patterning marker, was also reduced. As loss of function of these genes results in severe nervous system impairments in mice, our data suggest that the 3-D hESC-derived model could be used to test for Nano-DNT.

  5. Kinetics of Hexagonal-Body-Centered Cubic Transition in a Triblock Copolymer in a Selective Solvent: Time-Resolved Small-Angle X-ray Scattering Measurements and Model Calculations

    SciTech Connect

    Li,M.; Liu, Y.; Nie, H.; Bansil, R.; Steinhart, M.

    2007-01-01

    Time-resolved small-angle X-ray scattering (SAXS) was used to examine the kinetics of the transition from hexagonal (hex) cylinders to body-centered cubic (bcc) spheres at various temperatures in poly(styrene-b-ethylene-co-butylene-b-styrene) (SEBS) in mineral oil, a selective solvent for the middle ethylene-co-butylene (EB) block. Temperature-ramp SAXS and rheology measurements show the hex to bcc order-order transition (OOT) at 127 C and order-disorder transition (ODT) at 180 C. We also observed the metastability limit of hex in bcc with a spinodal temperature, Ts 150 C. The OOT exhibits three stages and occurs via a nucleation and growth mechanism when the final temperature Tf < Ts. Spinodal decomposition in a continuous ordering system was seen when Ts < Tf < TODT. We observed that hex cylinders transform to disordered spheres via a transient bcc state. We develop a geometrical model of coupled anisotropic fluctuations and calculate the scattering which shows very good agreement with the SAXS data. The splitting of the primary peak into two peaks when the cylinder spacing and modulation wavelength are incommensurate predicted by the model is confirmed by analysis of the SAXS data.

  6. Picosecond time-resolved measurements of dense plasma line shifts

    DOE PAGES

    Stillman, C. R.; Nilson, P. M.; Ivancic, S. T.; ...

    2017-06-13

    Picosecond time-resolved x-ray spectroscopy is used to measure the spectral line shift of the 1s2p–1s2 transition in He-like Al ions as a function of the instantaneous plasma conditions. The plasma temperature and density are inferred from the Al Heα complex using a nonlocal-thermodynamic-equilibrium atomic physics model. The experimental spectra show a linearly increasing red shift for electron densities of 1 to 5 × 1023 cm–3. Furthermore, the measured line shifts are broadly consistent with a generalized analytic line-shift model based on calculations of a self-consistent field ion sphere model.

  7. Time Resolved Phonon Spectroscopy, Version 1.0

    SciTech Connect

    Goett, Johnny; Zhu, Brian

    2016-12-22

    TRPS code was developed for the project "Time Resolved Phonon Spectroscopy". Routines contained in this piece of software were specially created to model phonon generation and tracking within materials that interact with ionizing radiation, particularly applicable to the modeling of cryogenic radiation detectors for dark matter and neutrino research. These routines were created to link seamlessly with the open source Geant4 framework for the modeling of radiation transport in matter, with the explicit intent of open sourcing them for eventual integration into that code base.

  8. Picosecond time-resolved measurements of dense plasma line shifts

    NASA Astrophysics Data System (ADS)

    Stillman, C. R.; Nilson, P. M.; Ivancic, S. T.; Golovkin, I. E.; Mileham, C.; Begishev, I. A.; Froula, D. H.

    2017-06-01

    Picosecond time-resolved x-ray spectroscopy is used to measure the spectral line shift of the 1 s 2 p -1 s2 transition in He-like Al ions as a function of the instantaneous plasma conditions. The plasma temperature and density are inferred from the Al H eα complex using a nonlocal-thermodynamic-equilibrium atomic physics model. The experimental spectra show a linearly increasing redshift for electron densities of 1 -5 ×1023c m-3 . The measured line shifts are broadly consistent with a generalized analytic line-shift model based on calculations of a self-consistent field ion-sphere model.

  9. Relationship between time-resolved and non-time-resolved Beer-Lambert law in turbid media.

    PubMed

    Nomura, Y; Hazeki, O; Tamura, M

    1997-06-01

    The time-resolved Beer-Lambert law proposed for oxygen monitoring using pulsed light was extended to the non-time-resolved case in a scattered medium such as living tissues with continuous illumination. The time-resolved Beer-Lambert law was valid for the phantom model and living tissues in the visible and near-infrared regions. The absolute concentration and oxygen saturation of haemoglobin in rat brain and thigh muscle could be determined. The temporal profile of rat brain was reproduced by Monte Carlo simulation. When the temporal profiles of rat brain under different oxygenation states were integrated with time, the absorbance difference was linearly related to changes in the absorption coefficient. When the simulated profiles were integrated, there was a linear relationship within the absorption coefficient which was predicted for fractional inspiratory oxygen concentration from 10 to 100% and, in the case beyond the range of the absorption coefficient, the deviation from linearity was slight. We concluded that an optical pathlength which is independent of changes in the absorption coefficient is a good approximation for near-infrared oxygen monitoring.

  10. Time-resolved Temperature Measurements in SSPX

    SciTech Connect

    Ludington, A R; Hill, D N; McLean, H S; Moller, J; Wood, R D

    2006-08-14

    We seek to measure time-resolved electron temperatures in the SSPX plasma using soft X-rays from free-free Bremsstrahlung radiation. To increase sensitivity to changes in temperature over the range 100-300 eV, we use two photodiode detectors sensitive to different soft X-ray energies. The detectors, one with a Zr/C coating and the other with a Ti/Pd coating, view the plasma along a common line of sight tangential to the magnetic axis of the spheromak, where the electron temperature is a maximum. The comparison of the signals, over a similar volume of plasma, should be a stronger function of temperature than a single detector in the range of Te< 300 eV. The success of using photodiodes to detect changing temperatures along a chord will make the case for designing an array of the detectors, which could provide a time changing temperature profile over a larger portion of the plasma.

  11. Time resolved ion beam induced charge collection

    SciTech Connect

    SEXTON,FREDERICK W.; WALSH,DAVID S.; DOYLE,BARNEY L.; DODD,PAUL E.

    2000-04-01

    Under this effort, a new method for studying the single event upset (SEU) in microelectronics has been developed and demonstrated. Called TRIBICC, for Time Resolved Ion Beam Induced Charge Collection, this technique measures the transient charge-collection waveform from a single heavy-ion strike with a {minus}.03db bandwidth of 5 GHz. Bandwidth can be expanded up to 15 GHz (with 5 ps sampling windows) by using an FFT-based off-line waveform renormalization technique developed at Sandia. The theoretical time resolution of the digitized waveform is 24 ps with data re-normalization and 70 ps without re-normalization. To preserve the high bandwidth from IC to the digitizing oscilloscope, individual test structures are assembled in custom high-frequency fixtures. A leading-edge digitized waveform is stored with the corresponding ion beam position at each point in a two-dimensional raster scan. The resulting data cube contains a spatial charge distribution map of up to 4,096 traces of charge (Q) collected as a function of time. These two dimensional traces of Q(t) can cover a period as short as 5 ns with up to 1,024 points per trace. This tool overcomes limitations observed in previous multi-shot techniques due to the displacement damage effects of multiple ion strikes that changed the signal of interest during its measurement. This system is the first demonstration of a single-ion transient measurement capability coupled with spatial mapping of fast transients.

  12. Accuracy of both virtual and printed 3-dimensional models for volumetric measurement of alveolar clefts before grafting with alveolar bone compared with a validated algorithm: a preliminary investigation.

    PubMed

    Kasaven, C P; McIntyre, G T; Mossey, P A

    2017-01-01

    Our objective was to assess the accuracy of virtual and printed 3-dimensional models derived from cone-beam computed tomographic (CT) scans to measure the volume of alveolar clefts before bone grafting. Fifteen subjects with unilateral cleft lip and palate had i-CAT cone-beam CT scans recorded at 0.2mm voxel and sectioned transversely into slices 0.2mm thick using i-CAT Vision. Volumes of alveolar clefts were calculated using first a validated algorithm; secondly, commercially-available virtual 3-dimensional model software; and finally 3-dimensional printed models, which were scanned with microCT and analysed using 3-dimensional software. For inter-observer reliability, a two-way mixed model intraclass correlation coefficient (ICC) was used to evaluate the reproducibility of identification of the cranial and caudal limits of the clefts among three observers. We used a Friedman test to assess the significance of differences among the methods, and probabilities of less than 0.05 were accepted as significant. Inter-observer reliability was almost perfect (ICC=0.987). There were no significant differences among the three methods. Virtual and printed 3-dimensional models were as precise as the validated computer algorithm in the calculation of volumes of the alveolar cleft before bone grafting, but virtual 3-dimensional models were the most accurate with the smallest 95% CI and, subject to further investigation, could be a useful adjunct in clinical practice. Copyright © 2016 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  13. A Novel 3 Dimensional Stromal-based Model for In Vitro Chemotherapy Sensitivity Testing of Leukemia Cells

    PubMed Central

    Aljitawi, Omar S.; Li, Dandan; Xiao, Yinghua; Zhang, Da; Ramachandran, Karthik; Stehno-Bittel, Lisa; Van Veldhuizen, Peter; Lin, Tara L.; Kambhampati, Suman; Garimella, Rama

    2014-01-01

    The disparate responses of leukemia cells to chemotherapy in vivo, compared to in vitro, is partly related to the interactions of leukemic cells and the 3 dimensional (3D) bone marrow stromal microenvironment. We investigated the effects of chemotherapy agents on leukemic cell lines co-cultured with human bone marrow mesenchymal stem cell (hu-BM-MSC) in 3D. Comparison was made to leukemic cells treated in suspension, or grown on a hu-BM-MSC monolayer (2D conditions). We demonstrated that leukemic cells cultured in 3D were more resistant to drug-induced apoptosis compared to cells cultured in 2D or in suspension. We also demonstrated significant differences in leukemic cell response to chemotherapy using different leukemic cell lines cultured in 3D. We suggest that the differential responses to chemotherapy in 3D may be related to the expression of N-cadherin in the co-culture system. This unique model provides an opportunity to study leukemic cell responses to chemotherapy in 3D. PMID:23566162

  14. A 3-Dimensional Numerical Modelling Study on the Effects of Different Stress Regimes on the Magnitude of Induced Seismic Events

    NASA Astrophysics Data System (ADS)

    Amini, A.; Eberhardt, E.

    2016-12-01

    Producing oil and gas from shale reservoirs requires permeability enhancement treatments. This is achieved by injecting fluid under pressure to either propagate cracks through the rock (hydraulic fracture) or to stimulate slip across pre-existing fractures (hydroshear), which allows gas or oil to flow more readily into the well bore. After treatment is performed, the fluid is disposed of by injecting it back into the ground. The injection of these fluids, whether related to permeability enhancement or waste water disposal , into deep formations serves to create localized increases in pore pressures and reductions in the effective normal stresses acting on critically stressed faults, resulting in induced earthquakes. There have been numerous reports of anomalous seismic events with high magnitudes felt on surface that have given rise to public concerns. However, it must be recognized that different producing fields in Canada and the U.S. are situated in different tectonic regimes that favour different fault slip mechanisms. This study will explore the importance of stress regime, comparing the generation of induced seismicity under thrust versus strike slip conditions, with focus on their respective magnitudes distributions. To do so, we will first study empirical data pertaining to recorded seismicity related to hydraulic fracture operations with respect to source mechanisms and magnitude distributions. These will be analyzed in parallel with a series of advanced 3-dimensional numerical models using the distinct element code 3DEC to simulate fault slip under different stress regimes.

  15. Mycoplasma genitalium Infection Activates Cellular Host Defense and Inflammation Pathways in a 3-Dimensional Human Endocervical Epithelial Cell Model

    PubMed Central

    McGowin, Chris L.; Radtke, Andrea L.; Abraham, Kyle; Martin, David H.; Herbst-Kralovetz, Melissa

    2013-01-01

    Background. Because Mycoplasma genitalium is a prevalent and emerging cause of sexually transmitted infections, understanding the mechanisms by which M. genitalium elicits mucosal inflammation is an essential component to managing lower and upper reproductive tract disease syndromes in women. Methods. We used a rotating wall vessel bioreactor system to create 3-dimensional (3-D) epithelial cell aggregates to model and assess endocervical infection by M. genitalium. Results. Attachment of M. genitalium to the host cell's apical surface was observed directly and confirmed using immunoelectron microscopy. Bacterial replication was observed from 0 to 72 hours after inoculation, during which time host cells underwent ultrastructural changes, including reduction of microvilli, and marked increases in secretory vesicle formation. Using genome-wide transcriptional profiling, we identified a host defense and inflammation signature activated by M. genitalium during acute infection (48 hours after inoculation) that included cytokine and chemokine activity and secretion of factors for antimicrobial defense. Multiplex bead-based protein assays confirmed secretion of proinflammatory cytokines, several of which are involved in leukocyte recruitment and hypothesized to enhance susceptibility to human immunodeficiency type 1 infection. Conclusions. These findings provide insight into key molecules and pathways involved in innate recognition of M. genitalium and the response to acute infection in the human endocervix. PMID:23493725

  16. A Geometric Modelling Approach to Determining the Best Sensing Coverage for 3-Dimensional Acoustic Target Tracking in Wireless Sensor Networks

    PubMed Central

    Pashazadeh, Saeid; Sharifi, Mohsen

    2009-01-01

    Existing 3-dimensional acoustic target tracking methods that use wired/wireless networked sensor nodes to track targets based on four sensing coverage do not always compute the feasible spatio-temporal information of target objects. To investigate this discrepancy in a formal setting, we propose a geometric model of the target tracking problem alongside its equivalent geometric dual model that is easier to solve. We then study and prove some properties of dual model by exploiting its relationship with algebra. Based on these properties, we propose a four coverage axis line method based on four sensing coverage and prove that four sensing coverage always yields two dual correct answers; usually one of them is infeasible. By showing that the feasible answer can be only sometimes identified by using a simple time test method such as the one proposed by ourselves, we prove that four sensing coverage fails to always yield the feasible spatio-temporal information of a target object. We further prove that five sensing coverage always gives the feasible position of a target object under certain conditions that are discussed in this paper. We propose three extensions to four coverage axis line method, namely, five coverage extent point method, five coverage extended axis lines method, and five coverage redundant axis lines method. Computation and time complexities of all four proposed methods are equal in the worst cases as well as on average being equal to Θ(1) each. Proposed methods and proved facts about capabilities of sensing coverage degree in this paper can be used in all other methods of acoustic target tracking like Bayesian filtering methods. PMID:22423198

  17. Assessment and Treatment of Peritumoral Cortical Veins in Parasagittal Meningiomas with Application of 3-Dimensional Imaging Fusion Model.

    PubMed

    Yin, Tengkun; Gu, Jianjun; Huang, Yinxing; Wei, Liangfeng; Gao, Jinxi; Wang, Shousen

    2017-08-01

    Operation of cortical veins is the keystone of parasagittal meningioma (PSM) resection. Little is known about pathologic changes of the veins and proper treatment. We built 3-dimensional (3D) image fusion models by neuronavigation to analyze the features of peritumoral cortical veins for PSMs and explore intraoperative treatment options. We performed a prospective study of 42 consecutive surgically treated PSM patients who underwent preoperative evaluation of peritumoral cortical veins using a 3D venous-tumor fusion model established by a neuronavigation system. We categorized cortical veins into 3 types: single-end anastomosis (type a), tumor-to-end anastomosis (type b), and end-to-end anastomosis (type c). We present surgical strategies to operate these veins. Preoperative evaluation demonstrated 39 patients with peritumoral cortical veins. The 3D models show 100% of the veins (95 in total), which were confirmed intraoperation. The postoperative complication rates after vein injury were 60% (type a), 16.7% (type c), and 0% (type b). Ten patients (23.8%) had residual tumor because of venous protection (equal to Simpson grade III). After correlation analysis, type b and c cortical veins were positively correlated with tumor volume. The anastomoses of cortical veins may provide compensation for venous transaction. There may be a time-evolution relationship between different cortical veins (type a to c to b). Treatment of cortical veins should follow the following principles: single-end veins must be protected, tumor-to-end veins should be transacted directly, and end-to-end veins could be cut selectivity based on the degree of occlusion of the superior sagittal sinus. Detailed preoperative assessment of peritumoral cortical veins is critical for proper treatment. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Time resolved cryogenic cooling analysis of the Cornell Injector Cryomodule

    NASA Astrophysics Data System (ADS)

    Eichhorn, R.; Markham, S.; Smith, E.; Quigley, P.

    2015-12-01

    Managing parallel cryogenic flows has become a key challenge in designing efficient and smart cryo-modules for particle accelerators. In analysing the heating dynamics of the Cornell high current injector module a computational tool has been set-up allowing time resolved analysis and optimization. We describe the computational methods and data sets we have used, report the results and compare them to measured data from the module being in good agreement. Mitigation strategies developed on basis of this model have helped us in pushing the operational limitations.

  19. Use of 3-dimensional printing technology and silicone modeling in surgical simulation: development and face validation in pediatric laparoscopic pyeloplasty.

    PubMed

    Cheung, Carling L; Looi, Thomas; Lendvay, Thomas S; Drake, James M; Farhat, Walid A

    2014-01-01

    Pediatric laparoscopy poses unique training challenges owing to smaller workspaces, finer sutures used, and potentially more delicate tissues that require increased surgical dexterity when compared with adult analogs. We describe the development and face validation of a pediatric pyeloplasty simulator using a low-cost laparoscopic dry-laboratory model developed with 3-dimensional (3D) printing and silicone modeling. The organs (the kidney, renal pelvis, and ureter) were created in a 3-step process where molds were created with 3D modeling software, printed with a Spectrum Z510 3D printer, and cast with Dragon Skin 30 silicone rubber. The model was secured in a laparoscopy box trainer. A pilot study was conducted at a Canadian Urological Association meeting. A total of 24 pediatric urology fellows and 3 experienced faculty members then assessed our skills module during a minimally invasive surgery training course. Participants had 60 minutes to perform a right-side pyeloplasty using laparoscopic tools and 5-0 VICRYL suture. Face validity was demonstrated on a 5-point Likert scale. The dry-laboratory model consists of a kidney, a replaceable dilated renal pelvis and ureter with an obstructed ureteropelvic junction, and an overlying peritoneum with an inscribed fundamentals of laparoscopic surgery pattern-cutting exercise. During initial validation at the Canadian Urological Association, participants rated (out of 5) 4.75 ± 0.29 for overall impression, 4.50 ± 0.41 for realism, and 4.38 ± 0.48 for handling. During the minimally invasive surgery course, 22 of 24 fellows and all the faculty members completed the scoring. Usability was rated 4 or 5 by 14 participants (overall, 3.6 ± 1.22 by novices and 3.7 ± 0.58 by experts), indicating that they would use the model in their own training and teaching. Esthetically, the model was rated 3.5 ± 0.74 (novices) and 3.3 ± 0.58 (experts). We developed a pediatric pyeloplasty simulator by applying a low-cost reusable model

  20. Femoral Graft-Tunnel Angles in Posterior Cruciate Ligament Reconstruction: Analysis with 3-Dimensional Models and Cadaveric Experiments

    PubMed Central

    Kim, Sung-Jae; Chun, Yong-Min; Moon, Hong-Kyo; Jang, Jae-Won

    2013-01-01

    Purpose The purpose of this study was to compare four graft-tunnel angles (GTA), the femoral GTA formed by three different femoral tunneling techniques (the outside-in, a modified inside-out technique in the posterior sag position with knee hyperflexion, and the conventional inside-out technique) and the tibia GTA in 3-dimensional (3D) knee flexion models, as well as to examine the influence of femoral tunneling techniques on the contact pressure between the intra-articular aperture of the femoral tunnel and the graft. Materials and Methods Twelve cadaveric knees were tested. Computed tomography scans were performed at different knee flexion angles (0°, 45°, 90°, and 120°). Femoral and tibial GTAs were measured at different knee flexion angles on the 3D knee models. Using pressure sensitive films, stress on the graft of the angulation of the femoral tunnel aperture was measured in posterior cruciate ligament reconstructed cadaveric knees. Results Between 45° and 120° of knee flexion, there were no significant differences between the outside-in and modified inside-out techniques. However, the femoral GTA for the conventional inside-out technique was significantly less than that for the other two techniques (p<0.001). In cadaveric experiments using pressure-sensitive film, the maximum contact pressure for the modified inside-out and outside-in technique was significantly lower than that for the conventional inside-out technique (p=0.024 and p=0.017). Conclusion The conventional inside-out technique results in a significantly lesser GTA and higher stress at the intra-articular aperture of the femoral tunnel than the outside-in technique. However, the results for the modified inside-out technique are similar to those for the outside-in technique. PMID:23709438

  1. Development and Application of a 3-Dimensional Finite Element Model for Remediation Wellfield Management at Lawrence Livermore National Laboratory

    NASA Astrophysics Data System (ADS)

    Mansoor, K.; Maley, M. P.; Demir, Z.; Noyes, C.

    2001-12-01

    Lawrence Livermore National Laboratory (LLNL), which is on the Superfund National Priorities List, is implementing an extensive ground water remediation program. The environmental investigation covers an area of about 2 square miles, and is underlain by a thick sequence of heterogeneous alluvial sediments. These sediments have been subdivided into hydrostratigraphic units (HSUs) bounded by thin confining layers that were identified using a deterministic approach. LLNL currently operates a large ground water extraction system that includes 80 ground water extraction wells connected to 25 separate treatment facilities. These combined facilities treated about 308 million gallons of ground water at an average combined flow rate of 600 gpm, and removed about 270 kg of volatile organic compounds (VOC's). To better manage this large complex remediation system, a 3-dimensional, finite-element numerical model was developed using FEFLOW. The model simulated a 7 square-mile portion of the large Livermore Valley ground water basin. The quality of the input data varied from highly detailed, in the environmental investigation areas, to sparse, near some of the model domain boundaries. These different data sets had to be integrated to obtain the necessary boundary conditions and input parameters for the model. Hydraulic conductivities were averaged from measured lithologic descriptions and hydraulic test data. Boundary conditions were based on a local and regional assessment of groundwater elevation data representative of observed inflow/outflow boundaries. The model was initially calibrated to a set of 8 distinct hydrologic stress periods over 12 years. Initial flow calibration for the model was achieved using the parameter estimation tool PEST. Through successive data analysis and calibration, optimal parameters were established for each HSU and expanded to 35 hydrologic stress periods covering the entire recorded hydrologic history. VOC transport was calibrated to 9 years of

  2. A 3-Dimensional Model of Water-Bearing Sequences in the Dominguez Gap Region, Long Beach, California

    USGS Publications Warehouse

    Ponti, Daniel J.; Ehman, Kenneth D.; Edwards, Brian D.; Tinsley, John C.; Hildenbrand, Thomas; Hillhouse, John W.; Hanson, Randall T.; McDougall, Kristen; Powell, Charles L.; Wan, Elmira; Land, Michael; Mahan, Shannon; Sarna-Wojcicki, Andrei M.

    2007-01-01

    A 3-dimensional computer model of the Quaternary sequence stratigraphy in the Dominguez gap region of Long Beach, California has been developed to provide a robust chronostratigraphic framework for hydrologic and tectonic studies. The model consists of 13 layers within a 16.5 by 16.1 km (10.25 by 10 mile) square area and extends downward to an altitude of -900 meters (-2952.76 feet). Ten sequences of late Pliocene to Holocene age are identified and correlated within the model. Primary data to build the model comes from five reference core holes, extensive high-resolution seismic data obtained in San Pedro Bay, and logs from several hundred water and oil wells drilled in the region. The model is best constrained in the vicinity of the Dominguez gap seawater intrusion barrier where a dense network of subsurface data exist. The resultant stratigraphic framework and geologic structure differs significantly from what has been proposed in earlier studies. An important new discovery from this approach is the recognition of ongoing tectonic deformation throughout nearly all of Quaternary time that has impacted the geometry and character of the sequences. Anticlinal folding along a NW-SE trend, probably associated with Quaternary reactivation of the Wilmington anticline, has uplifted and thinned deposits along the fold crest, which intersects the Dominguez gap seawater barrier near Pacific Coast Highway. A W-NW trending fault system that approximately parallels the fold crest has also been identified. This fault progressively displaces all but the youngest sequences down to the north and serves as the southern termination of the classic Silverado aquifer. Uplift and erosion of fining-upward paralic sequences along the crest of the young fold has removed or thinned many of the fine-grained beds that serve to protect the underlying Silverado aquifer from seawater contaminated shallow groundwater. As a result of this process, the potential exists for vertical migration of

  3. Time resolved spectral behavior of bright BATSE precursors

    NASA Astrophysics Data System (ADS)

    Burlon, D.; Ghirlanda, G.; Ghisellini, G.; Greiner, J.; Celotti, A.

    2009-10-01

    Aims: Gamma ray bursts (GRBs) are sometimes preceded by dimmer emission episodes, called “precursors”, whose nature is still a puzzle: they could either have the same origin as the main emission episode or they could be due to another mechanism. We investigate if precursors have some spectral distinctive feature with respect to the main GRB episodes. Methods: To this aim we compare the spectral evolution of the precursor with that of the main GRB event. We also study if and how the spectral parameters, and in particular the peak of the ν Fν spectrum of time resolved spectra, correlates with the flux. This allows us to test if the spectra of the precursor and of the main event belong to the same correlation (if any). We searched GRBs with precursor activity in the complete sample of 2704 bursts detected by BATSE finding that 12% of GRBs have one or more precursors. Among these we considered the bursts with time resolved spectral analysis performed by Kaneko et al. ( 2006, ApJS, 166, 298), selecting those having at least two time resolved spectra for the precursor. Results: We find that precursors and main events have very similar spectral properties. The spectral evolution within precursors has similar trends as the spectral evolution observed in the subsequent peaks. Also the typical spectral parameters of the precursors are similar to those of the main GRB events. Moreover, in several cases we find that within the precursors the peak energy of the spectrum is correlated with the flux similarly to what happens in the main GRB event. This strongly favors models in which the precursor is due to the same fireball physics of the main emission episodes. Figures 8 to 41 are only available in electronic form at http://www.aanda.org

  4. V-stand--a versatile surgical platform for oromandibular reconstruction using a 3-dimensional virtual modeling system.

    PubMed

    Reiser, Vadim; Alterman, Michael; Shuster, Amir; Kleinman, Shlomi; Shlomi, Benjamin; Yanko-Arzi, Ravit; Zaretski, Arik; Amir, Aharon; Fliss, Dan M

    2015-06-01

    The challenge of oromandibular reconstruction (OMR) after oncologic resections has been repeatedly addressed in the literature. Although final oncologic margins can be decided only during surgery, various attempts have been made to create an ideal and accurate platform for OMR. The purpose of this article is to present the V-stand, a versatile surgical platform for OMR using a 3-dimensional (3D) virtual modeling system. Seventeen patients requiring an OMR were included in the study. A presurgical computed tomogram was obtained and virtual resection and reconstruction with a free fibular flap were planned using 3D virtual surgery software. The mandible was reconstructed intraoperatively using the V-stand, which served as a template for the lower border of the mandible and the lateral aspects of the stand were fixed to the proximal mandibular segments using 2-mm titanium screws. Patients' average age was 53 years (5 to 72 yr). Median follow-up was 19 months (2 to 35 months). All reconstructed mandibles resulted in good function and esthetics. The V-stand offers a safe and time-efficient method for OMR. It provides an excellent means for accurate spatial positioning of a fibular free flap. The V-stand preserves the original dimensions of the reconstructed mandible and can overcome surgical ablation modifications because it is not dependent on the precision of the resection, but rather provides a mold for the entire mandible. Copyright © 2015 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

  5. Time-resolved quasielastic neutron scattering studies of native photosystems.

    PubMed

    Pieper, Jörg

    2010-01-01

    The internal molecular dynamics of proteins plays an important role in a number of functional processes in native photosystems. Prominent examples include the photocycle of bacteriorhodopsin and electron transfer in the reaction center of plant photosystem II. In this regard, the recently developed technique of time-resolved quasielastic neutron scattering with laser excitation opens up new perspectives for the study of protein/membrane dynamics in specific functional states of even complex systems. The first direct observation of a functionally modulated protein dynamics has just recently been reported for the model system bacteriorhodopsin (Pieper et al., Phys. Rev. Lett. 100, 2008, 228103.), where a transient softening of the protein was observed on a timescale of approximately 1 ms along with the large-scale structural change in the M-intermediate of bacteriorhodopsin. In contrast, photosystem II membrane fragments with inhibited electron transfer show a suppression of protein dynamics approximately 160 mus after the actinic laser flash (Pieper and Renger, Biochemistry 48, 2009, 6111). This effect may reflect aggregation-like conformational changes capable of dissipation of excess excitation energy to prevent photodamage in the absence of Q(A)-->Q(B) electron transfer. These findings indicate that proteins exhibit a remarkable flexibility to accommodate different functional processes. This contribution will discuss methodical aspects, challenges, and recent applications of laser-excited, time-resolved quasielastic neutron scattering.

  6. Time-resolved multispectral imaging of combustion reaction

    NASA Astrophysics Data System (ADS)

    Huot, Alexandrine; Gagnon, Marc-André; Jahjah, Karl-Alexandre; Tremblay, Pierre; Savary, Simon; Farley, Vincent; Lagueux, Philippe; Guyot, Éric; Chamberland, Martin; Marcotte, Fréderick

    2015-05-01

    Thermal infrared imaging is a field of science that evolves rapidly. Scientists have used for years the simplest tool: thermal broadband cameras. This allows to perform target characterization in both the longwave (LWIR) and midwave (MWIR) infrared spectral range. Infrared thermal imaging is used for a wide range of applications, especially in the combustion domain. For example, it can be used to follow combustion reactions, in order to characterize the injection and the ignition in a combustion chamber or even to observe gases produced by a flare or smokestack. Most combustion gases such as carbon dioxide (CO2) selectively absorb/emit infrared radiation at discrete energies, i.e. over a very narrow spectral range. Therefore, temperatures derived from broadband imaging are not reliable without prior knowledge about spectral emissivity. This information is not directly available from broadband images. However, spectral information is available using spectral filters. In this work, combustion analysis was carried out using Telops MS-IR MW camera which allows multispectral imaging at a high frame rate. A motorized filter wheel allowing synchronized acquisitions on eight (8) different channels was used to provide time-resolved multispectral imaging of combustion products of a candle in which black powder has been burnt to create a burst. It was then possible to estimate the temperature by modeling spectral profile derived from information obtained with the different spectral filters. Comparison with temperatures obtained using conventional broadband imaging illustrates the benefits of time-resolved multispectral imaging for the characterization of combustion processes.

  7. Time-resolved multispectral imaging of combustion reactions

    NASA Astrophysics Data System (ADS)

    Huot, Alexandrine; Gagnon, Marc-André; Jahjah, Karl-Alexandre; Tremblay, Pierre; Savary, Simon; Farley, Vincent; Lagueux, Philippe; Guyot, Éric; Chamberland, Martin; Marcotte, Frédérick

    2015-10-01

    Thermal infrared imaging is a field of science that evolves rapidly. Scientists have used for years the simplest tool: thermal broadband cameras. These allow to perform target characterization in both the longwave (LWIR) and midwave (MWIR) infrared spectral range. Infrared thermal imaging is used for a wide range of applications, especially in the combustion domain. For example, it can be used to follow combustion reactions, in order to characterize the injection and the ignition in a combustion chamber or even to observe gases produced by a flare or smokestack. Most combustion gases, such as carbon dioxide (CO2), selectively absorb/emit infrared radiation at discrete energies, i.e. over a very narrow spectral range. Therefore, temperatures derived from broadband imaging are not reliable without prior knowledge of spectral emissivity. This information is not directly available from broadband images. However, spectral information is available using spectral filters. In this work, combustion analysis was carried out using a Telops MS-IR MW camera, which allows multispectral imaging at a high frame rate. A motorized filter wheel allowing synchronized acquisitions on eight (8) different channels was used to provide time-resolved multispectral imaging of combustion products of a candle in which black powder has been burnt to create a burst. It was then possible to estimate the temperature by modeling spectral profiles derived from information obtained with the different spectral filters. Comparison with temperatures obtained using conventional broadband imaging illustrates the benefits of time-resolved multispectral imaging for the characterization of combustion processes.

  8. Nonadiabatic and Time-Resolved Photoelectron Spectroscopy for Molecular Systems.

    PubMed

    Flick, Johannes; Appel, Heiko; Rubio, Angel

    2014-04-08

    We quantify the nonadiabatic contributions to the vibronic sidebands of equilibrium and explicitly time-resolved nonequilibrium photoelectron spectra for a vibronic model system of trans-polyacetylene. Using exact diagonalization, we directly evaluate the sum-over-states expressions for the linear-response photocurrent. We show that spurious peaks appear in the Born-Oppenheimer approximation for the vibronic spectral function, which are not present in the exact spectral function of the system. The effect can be traced back to the factorized nature of the Born-Oppenheimer initial and final photoemission states and also persists when either only initial or final states are replaced by correlated vibronic states. Only when correlated initial and final vibronic states are taken into account are the spurious spectral weights of the Born-Oppenheimer approximation suppressed. In the nonequilibrium case, we illustrate for an initial Franck-Condon excitation and an explicit pump-pulse excitation how the vibronic wavepacket motion of the system can be traced in the time-resolved photoelectron spectra as a function of the pump-probe delay.

  9. Use of 3-Dimensional Volumetric Modeling of Adrenal Gland Size in Patients with Primary Pigmented Nodular Adrenocortical Disease.

    PubMed

    Chrysostomou, P P; Lodish, M B; Turkbey, E B; Papadakis, G Z; Stratakis, C A

    2016-04-01

    Primary pigmented nodular adrenocortical disease (PPNAD) is a rare type of bilateral adrenal hyperplasia leading to hypercortisolemia. Adrenal nodularity is often appreciable with computed tomography (CT); however, accurate radiologic characterization of adrenal size in PPNAD has not been studied well. We used 3-dimensional (3D) volumetric analysis to characterize and compare adrenal size in PPNAD patients, with and without Cushing's syndrome (CS). Patients diagnosed with PPNAD and their family members with known mutations in PRKAR1A were screened. CT scans were used to create 3D models of each adrenal. Criteria for biochemical diagnosis of CS included loss of diurnal variation and/or elevated midnight cortisol levels, and paradoxical increase in urinary free cortisol and/or urinary 17-hydroxysteroids after dexamethasone administration. Forty-five patients with PPNAD (24 females, 27.8±17.6 years) and 8 controls (19±3 years) were evaluated. 3D volumetric modeling of adrenal glands was performed in all. Thirty-eight patients out of 45 (84.4%) had CS. Their mean adrenal volume was 8.1 cc±4.1, 7.2 cc±4.5 (p=0.643) for non-CS, and 8.0cc±1.6 for controls. Mean values were corrected for body surface area; 4.7 cc/kg/m(2)±2.2 for CS, and 3.9 cc/kg/m(2)±1.3 for non-CS (p=0.189). Adrenal volume and midnight cortisol in both groups was positively correlated, r=0.35, p=0.03. We conclude that adrenal volume measured by 3D CT in patients with PPNAD and CS was similar to those without CS, confirming empirical CT imaging-based observations. However, the association between adrenal volume and midnight cortisol levels may be used as a marker of who among patients with PPNAD may develop CS, something that routine CT cannot do.

  10. Assessing agreement in measurements of orthodontic study models: Digital caliper on plaster models vs 3-dimensional software on models scanned by structured-light scanner.

    PubMed

    Wan Hassan, Wan Nurazreena; Othman, Siti Adibah; Chan, Chee Seng; Ahmad, Roshahida; Ali, Siti Nor'Ain; Abd Rohim, Anis

    2016-11-01

    In this study we aimed to compare measurements on plaster models using a digital caliper, and on 3-dimensional (3D) digital models, produced using a structured-light scanner, using 3D software. Fifty digital models were scanned from the same plaster models. Arch and tooth size measurements were made by 2 operators, twice. Calibration was done on 10 sets of models and checked using the Pearson correlation coefficient. Data were analyzed by error variances, repeatability coefficient, repeated-measures analysis of variance, and Bland-Altman plots. Error variances ranged between 0.001 and 0.044 mm for the digital caliper method, and between 0.002 and 0.054 mm for the 3D software method. Repeated-measures analysis of variance showed small but statistically significant differences (P <0.05) between the repeated measurements in the arch and buccolingual planes (0.011 and 0.008 mm, respectively). There were no statistically significant differences between methods and between operators. Bland-Altman plots showed that the mean biases were close to zero, and the 95% limits of agreement were within ±0.50 mm. Repeatability coefficients for all measurements were similar. Measurements made on models scanned by the 3D structured-light scanner were in good agreement with those made on conventional plaster models and were, therefore, clinically acceptable. Copyright © 2016. Published by Elsevier Inc.

  11. Examining Electron-Boson Coupling Using Time-Resolved Spectroscopy

    SciTech Connect

    Sentef, Michael; Kemper, Alexander F.; Moritz, Brian; Freericks, James K.; Shen, Zhi-Xun; Devereaux, Thomas P.

    2013-12-26

    Nonequilibrium pump-probe time-domain spectroscopies can become an important tool to disentangle degrees of freedom whose coupling leads to broad structures in the frequency domain. Here, using the time-resolved solution of a model photoexcited electron-phonon system, we show that the relaxational dynamics are directly governed by the equilibrium self-energy so that the phonon frequency sets a window for “slow” versus “fast” recovery. The overall temporal structure of this relaxation spectroscopy allows for a reliable and quantitative extraction of the electron-phonon coupling strength without requiring an effective temperature model or making strong assumptions about the underlying bare electronic band dispersion.

  12. Time-resolved pulsed EPR: microwave and optical detection

    SciTech Connect

    Trifunac, A.D.; Smith, J.P.

    1981-01-01

    Time-resolved pulsed EPR spectrometers are described. EPR spectra, kinetic profiles, and relaxation studies are used to illustrate some capabilities of the pulsed EPR experiment. Optical detection of time-resolved EPR spectra of radical ion pairs is used to study radical-ion recombination kinetics, recombination pathways, and the structure of radical anions and cations. 17 figures.

  13. Ultrafast time-resolved vibrational spectroscopies of carotenoids in photosynthesis.

    PubMed

    Hashimoto, Hideki; Sugisaki, Mitsuru; Yoshizawa, Masayuki

    2015-01-01

    This review discusses the application of time-resolved vibrational spectroscopies to the studies of carotenoids in photosynthesis. The focus is on the ultrafast time regime and the study of photophysics and photochemistry of carotenoids by femtosecond time-resolved stimulated Raman and four-wave mixing spectroscopies. This article is part of a Special Issue entitled: Vibrational spectroscopies and bioenergetic systems.

  14. Normal growth and development of the lips: a 3-dimensional study from 6 years to adulthood using a geometric model

    PubMed Central

    FERRARIO, VIRGILIO F.; SFORZA, CHIARELLA; SCHMITZ, JOHANNES H.; CIUSA, VERONICA; COLOMBO, ANNA

    2000-01-01

    A 3-dimensional computerised system with landmark representation of the soft-tissue facial surface allows noninvasive and fast quantitative study of facial growth. The aims of the present investigation were (1) to provide reference data for selected dimensions of lips (linear distances and ratios, vermilion area, volume); (2) to quantify the relevant growth changes; and (3) to evaluate sex differences in growth patterns. The 3-dimensional coordinates of 6 soft-tissue landmarks on the lips were obtained by an optoelectronic instrument in a mixed longitudinal and cross-sectional study (2023 examinations in 1348 healthy subjects between 6 y of age and young adulthood). From the landmarks, several linear distances (mouth width, total vermilion height, total lip height, upper lip height), the vermilion height-to-mouth width ratio, some areas (vermilion of the upper lip, vermilion of the lower lip, total vermilion) and volumes (upper lip volume, lower lip volume, total lip volume) were calculated and averaged for age and sex. Male values were compared with female values by means of Student's t test. Within each age group all lip dimensions (distances, areas, volumes) were significantly larger in boys than in girls (P < 0.05), with some exceptions in the first age groups and coinciding with the earlier female growth spurt, whereas the vermilion height-to-mouth width ratio did not show a corresponding sexual dimorphism. Linear distances in girls had almost reached adult dimensions in the 13–14 y age group, while in boys a large increase was still to occur. The attainment of adult dimensions was faster in the upper than in the lower lip, especially in girls. The method used in the present investigation allowed the noninvasive evaluation of a large sample of nonpatient subjects, leading to the definition of 3-dimensional normative data. Data collected in the present study could represent a data base for the quantitative description of human lip morphology from childhood to

  15. Time-resolved spin-dependent processes in magnetic field effects in organic semiconductors

    NASA Astrophysics Data System (ADS)

    Peng, Qiming; Li, Xianjie; Li, Feng

    2012-12-01

    We investigated the time-resolved magnetic field effects (MFEs) in tri-(8-hydroxyquinoline)-aluminum (Alq3) based organic light-emitting diodes (OLEDs) through the transient electroluminescence (EL) method. The values of magneto-electroluminescence (MEL) decrease with the time, and the decreasing slope is proportional to the driving voltage. Specifically, negative MELs are seen when the driving voltage is high enough (V > 11 V). We propose a model to elucidate the spin-dependent processes and theoretically simulate the time-resolved MELs. In particular, this dynamic analysis of time-resolved MELs reveals that the intersystem crossing between singlet and triplet electron-hole pairs and the triplet-triplet annihilation are responsible for the time-resolved MELs at the beginning and enduring periods of the pulse, respectively.

  16. Verification and transfer of thermal pollution model. Volume 3: Verification of 3-dimensional rigid-lid model

    NASA Technical Reports Server (NTRS)

    Lee, S. S.; Sengupta, S.; Nwadike, E. V.; Sinha, S. K.

    1982-01-01

    The six-volume report: describes the theory of a three dimensional (3-D) mathematical thermal discharge model and a related one dimensional (1-D) model, includes model verification at two sites, and provides a separate user's manual for each model. The 3-D model has two forms: free surface and rigid lid. The former, verified at Anclote Anchorage (FL), allows a free air/water interface and is suited for significant surface wave heights compared to mean water depth; e.g., estuaries and coastal regions. The latter, verified at Lake Keowee (SC), is suited for small surface wave heights compared to depth (e.g., natural or man-made inland lakes) because surface elevation has been removed as a parameter. These models allow computation of time-dependent velocity and temperature fields for given initial conditions and time-varying boundary conditions. The free-surface model also provides surface height variations with time.

  17. FXR LIA Optimization - Time-resolved OTR Emittance Measurement

    SciTech Connect

    Jacob, J; Ong, M; Wargo, P; LeSage, G

    2005-07-21

    The Flash X-Ray Radiography (FXR) facility at Lawrence Livermore National Laboratory utilizes a high current, long pulse linear induction accelerator to produce high doses of x-ray radiation. Accurate characterization of the transverse beam emittance is required in order to facilitate accelerator modeling and tuning efforts and, ultimately, to optimize the final focus spot size, yielding higher resolution radiographs. In addition to conventional magnet scan, pepper-pot, and multiple screen techniques, optical transition radiation (OTR) has been proven as a useful emittance measurement diagnostic and is particularly well suited to the FXR accelerator. We shall discuss the time-resolved emittance characterization of an induction linac electron beam using OTR, and we will present our experimental apparatus and analysis software. We shall also develop the theoretical background of beam emittance and transition radiation.

  18. Verification and transfer of thermal pollution model. Volume 2: User's manual for 3-dimensional free-surface model

    NASA Technical Reports Server (NTRS)

    Lee, S. S.; Sengupta, S.; Tuann, S. Y.; Lee, C. R.

    1982-01-01

    The six-volume report: describes the theory of a three-dimensional (3-D) mathematical thermal discharge model and a related one-dimensional (1-D) model, includes model verification at two sites, and provides a separate user's manual for each model. The 3-D model has two forms: free surface and rigid lid. The former, verified at Anclote Anchorage (FL), allows a free air/water interface and is suited for significant surface wave heights compared to mean water depth; e.g., estuaries and coastal regions. The latter, verified at Lake Keowee (SC), is suited for small surface wave heights compared to depth. These models allow computation of time-dependent velocity and temperature fields for given initial conditions and time-varying boundary conditions.

  19. ABSTRACTION OF INFORMATION FROM 2- AND 3-DIMENSIONAL PORFLOW MODELS INTO A 1-D GOLDSIM MODEL - 11404

    SciTech Connect

    Taylor, G.; Hiergesell, R.

    2010-11-16

    The Savannah River National Laboratory has developed a 'hybrid' approach to Performance Assessment modeling which has been used for a number of Performance Assessments. This hybrid approach uses a multi-dimensional modeling platform (PorFlow) to develop deterministic flow fields and perform contaminant transport. The GoldSim modeling platform is used to develop the Sensitivity and Uncertainty analyses. Because these codes are performing complementary tasks, it is incumbent upon them that for the deterministic cases they produce very similar results. This paper discusses two very different waste forms, one with no engineered barriers and one with engineered barriers, each of which present different challenges to the abstraction of data. The hybrid approach to Performance Assessment modeling used at the SRNL uses a 2-D unsaturated zone (UZ) and a 3-D saturated zone (SZ) model in the PorFlow modeling platform. The UZ model consists of the waste zone and the unsaturated zoned between the waste zone and the water table. The SZ model consists of source cells beneath the waste form to the points of interest. Both models contain 'buffer' cells so that modeling domain boundaries do not adversely affect the calculation. The information pipeline between the two models is the contaminant flux. The domain contaminant flux, typically in units of moles (or Curies) per year from the UZ model is used as a boundary condition for the source cells in the SZ. The GoldSim modeling component of the hybrid approach is an integrated UZ-SZ model. The model is a 1-D representation of the SZ, typically 1-D in the UZ, but as discussed below, depending on the waste form being analyzed may contain pseudo-2-D elements. A waste form at the Savannah River Site (SRS) which has no engineered barriers is commonly referred to as a slit trench. A slit trench, as its name implies, is an unlined trench, typically 6 m deep, 6 m wide, and 200 m long. Low level waste consisting of soil, debris, rubble, wood

  20. Time-resolved spectroscopy of low-dimensional semiconductor structures

    NASA Astrophysics Data System (ADS)

    Murphy, Joseph R.

    This dissertation is a survey of ultrafast time-resolved optical measurements conducted on a variety of low-dimensional semiconductor systems to further the understanding of the dynamic behavior in the following systems: ZnMnTe/ZnSe quantum dots, ZnTe/ZnMnSe quantum dots, InGaAs quantum wells, CdMnSe colloidal quantum dots, multi-shell CdSe/CdMnS/CdS colloidal nanoplatelets, and graphene and graphene-related solutions and films. Using time-resolved photoluminescence to study epitaxially-grown ZnTe and ZnMnTe quantum dots in corresponding ZnMnSe and ZnSe matrices, the location dependence of manganese ions in respect to magnetic polaron formation is shown. The structure with manganese ions located in the matrix exhibited magnetic polaron behavior consistent with previous literature, whereas the structure with the magnetic ions located within the quantum dots exhibited unconventional magnetic polaron properties. These properties, including temperature and magnetic field insensitivity, were explained through the use of a model that predicted an increased internal magnetic field due to a decreased effective volume of the magnetic polaron and a higher effective temperature due to laser heating. Magneto-time-resolved photoluminescence measurements on a system of colloidal CdMnSe quantum dots show that the magnetic polaron properties differ significantly from the epitaxially grown quantum dots. First the timescales at which the magnetic polaron forms and the polarization saturates are different by more than an order of magnitude, and second, the magnetic polaron energy exhibited step-like behavior as the strength of the externally applied magnetic field is increased. The field dependent MP formation energy that is observed experimentally is explained as due to the breaking of the antiferromagnetic coupling of Mn dimers within the QDs. This model is further verified by the observation of quantized behavior in the Zeeman energy splitting. Through the use of magneto

  1. Comparison of reconstructed rapid prototyping models produced by 3-dimensional printing and conventional stone models with different degrees of crowding.

    PubMed

    Wan Hassan, Wan Nurazreena; Yusoff, Yusnilawati; Mardi, Noor Azizi

    2017-01-01

    Rapid prototyping models can be reconstructed from stereolithographic digital study model data to produce hard-copy casts. In this study, we aimed to compare agreement and accuracy of measurements made with rapid prototyping and stone models for different degrees of crowding. The Z Printer 450 (3D Systems, Rock Hill, SC) reprinted 10 sets of models for each category of crowding (mild, moderate, and severe) scanned using a structured-light scanner (Maestro 3D, AGE Solutions, Pisa, Italy). Stone and RP models were measured using digital calipers for tooth sizes in the mesiodistal, buccolingual, and crown height planes and for arch dimension measurements. Bland-Altman and paired t test analyses were used to assess agreement and accuracy. Clinical significance was set at ±0.50 mm. Bland-Altman analysis showed the mean bias of measurements between the models to be within ±0.15 mm (SD, ±0.40 mm), but the 95% limits of agreement exceeded the cutoff point of ±0.50 mm (lower range, -0.81 to -0.41 mm; upper range, 0.34 to 0.76 mm). Paired t tests showed statistically significant differences for all planes in all categories of crowding except for crown height in the moderate crowding group and arch dimensions in the mild and moderate crowding groups. The rapid prototyping models were not clinically comparable with conventional stone models regardless of the degree of crowding. Copyright © 2017 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

  2. Accuracy and mechanical properties of orthodontic models printed 3-dimensionally from calcium sulfate before and after various postprinting treatments.

    PubMed

    Ledingham, Austin D; English, Jeryl D; Akyalcin, Sercan; Cozad, Benjamin E; Ontiveros, Joe C; Kasper, F Kurtis

    2016-12-01

    Dental models fabricated with 3-dimensional printing technologies are revolutionizing the practice of orthodontics, but they generally comprise polymeric materials that may not be suitable for certain applications, such as soldering appliances. The objective of this study was to investigate the dimensional accuracy and mechanical properties of 3-dimensional printed ceramic-based models before and after various treatments intended to improve their mechanical properties. Thirty identical models were printed 3-dimensionally from a calcium sulfate-based substrate and divided into 3 groups for treatment: high heat (250°C for 30 minutes), low heat (150°C for 30 minutes), and Epsom salt treatment. Each model was scanned before and after treatment with a laser scanner, and dimensional stability was analyzed by digital superimpositions using a best-fit algorithm. The models were weighed before and after treatment to evaluate mass changes. Additionally, 3-dimensional printed cylinders treated as described above and an untreated control group were subjected to compressive mechanical testing (n = 11 per group). The Epsom salt treatment group had statistically significant increases in both peak compressive stress and modulus of elasticity when compared with the other treatment groups. All treatment groups had statistically significant changes in mass, with the Epsom salt group gaining mass and the 2 heat-treatment groups losing mass. The low-temperature treatment group had a statistically significantly lower mean average for dimensional deviations (0.026 ± 0.010 mm) than did the other treatment groups (0.069 ± 0.006 and 0.059 ± 0.010 mm for high temperature and Epsom salt, respectively). Dental models printed 3-dimensionally with calcium sulfate and treated with Epsom salt showed significant improvement in compressive mechanical properties and retained clinically acceptable dimensional stability. Copyright © 2016 American Association of Orthodontists

  3. Theory and experiments on time-resolved reflectance from adult heads for functional tomographic imaging of brain activities

    NASA Astrophysics Data System (ADS)

    Tanifuji, T.; Suzuki, M.

    2014-02-01

    Finite difference time domain (FDTD) analysis has been formulated for predicting time-resolved reflectance from an adult head model with brain grooves containing a non-scattering layer. Mean delay (MD) dependences on source detector separation (d) and time-resolved reflectance calculated using the FDTD analysis were compared with in vivo experiments of human heads. It is shown that the theoretical and experimental MD dependences on d and the time-resolved reflectance are well predicted by FDTD analysis. These results have shown that tomographic imaging of brain activities is promising, which improves depth sensitivities by enhancing the contribution of late photons in time-resolved systems.

  4. Space-time resolved quantum field theory

    NASA Astrophysics Data System (ADS)

    Grobe, R.

    2009-11-01

    We have solved simplified model versions of the time-dependent Dirac and Yukawa equation numerically to study the time evolution of electrons, positrons and photons with full spatial resolution. The goal is to better understand how various particle creation and annihilation processes that require quantum field theory can be visualized. There are many open ended questions that we will address. Are particles and their antimatter companions created instantly, or do they require a certain minimum amount of time? Are they created at precisely the same location? What is the difference between a bare and a physical particle? Forces between two particles are usually understood on a microscopic level as the result of an exchange of bosonic particles. How can the same microscopic exchange mechanism lead to a repulsion as well as an attraction? Do these force intermediating particles ``know'' about the charges of the two interacting particles? How can one visualize this exchange? Does it really make sense to distinguish between virtual and real particles? We also examine how a bare electron can trigger the creation of a cloud of virtual photons around it.[4pt] In collaboration with R. Wagner, Intense Laser Physics Theory Unit, Illinois State University; C. Gerry, Lehman College and ILP-ISU; T. Cheng and Q. Su, Intense Laser Physics Theory Unit, Illinois State University.

  5. PREFACE: Time-resolved scanning tunnelling microscopy Time-resolved scanning tunnelling microscopy

    NASA Astrophysics Data System (ADS)

    Zandvliet, Harold J. W.; Lin, Nian

    2010-07-01

    out the potential landscape of the system (often a molecule or an atom) under study [4, 5]. However, the dynamical processes might also be induced by the tunnelling process itself [6, 7]. In the field of molecular science, excited single molecule experiments have been especially performed [8]. As a nice example, we refer to the work of Sykes' group [9] on thioether molecular rotors. In addition, several groups explore the possibility of combining time-resolved scanning tunnelling microscopy with optical techniques [10, 11]. Although the majority of studies that have been performed so far focus on rather simple systems under nearly ideal and well-defined conditions, we anticipate that time-resolved scanning tunnelling microscopy can also be applied in other research areas, such as biology and soft condensed matter, where the experimental conditions are often less ideal. We hope that readers will enjoy this collection of papers and that it will trigger them to further explore the possibilities of this simple, but powerful technique. References [1] Besenbacher F, Laegsgaard E and Stengaard I 2005 Mater. Today 8 26 [2] van Houselt A and Zandvliet H J W 2010 Rev. Mod. Phys. 82 1593 [3] Tringides M C and Hupalo M 2010 J. Phys.: Condens. Matter 22 264002 [4] Ronci F, Colonna S, Cricenti A and Le Lay G 2010 J. Phys.: Condens. Matter 22 264003 [5] van Houselt A, Poelsema B and Zandvliet H J W 2010 J. Phys.: Condens. Matter 22 264004 [6] Sprodowski C, Mehlhorn M and Morgenstern K 2010 J. Phys.: Condens. Matter 22 264005 [7] Saedi A, Poelsema B and Zandvliet H J W 2010 J. Phys.: Condens. Matter 22 264007 [8] Sloan P A 2010 J. Phys.: Condens. Matter 22 264001 [9] Jewell A D, Tierney H L, Baber A E, Iski E V, Laha M M and Sykes E C H 2010 J. Phys.: Condens. Matter 22 264006 [10] Riedel D 2010 J. Phys.: Condens. Matter 22 264009 [11] Terada Y, Yoshida S, Takeuchi O and Shigekawa H 2010 J. Phys.: Condens. Matter 22 264008

  6. Time resolved fluorescence of naproxen in organogel medium

    NASA Astrophysics Data System (ADS)

    Burguete, M. Isabel; Izquierdo, M. Angeles; Galindo, Francisco; Luis, Santiago V.

    2008-07-01

    The interaction between non-steroidal anti-inflammatory drug naproxen and the self assembled fibrillar network created by a low molecular weight organogelator has been probed by means of time resolved fluorescence spectroscopy.

  7. Thymine Dimer Formation probed by Time-Resolved Vibrational Spectroscopy

    NASA Astrophysics Data System (ADS)

    Schreier, Wolfgang J.; Schrader, Tobias E.; Roller, Florian O.; Gilch, Peter; Zinth, Wolfgang; Kohler, Bern

    Cyclobutane pyrimidine dimers are the major photoproducts formed when DNA is exposed to UV light. Femtosecond time-resolved vibrational spectroscopy reveals that thymine dimers are formed in thymidine oligonucleotides in an ultrafast photoreaction.

  8. High-speed detector for time-resolved diffraction studies

    PubMed Central

    Singh, Bipin; Miller, Stuart R.; Bhandari, Harish B.; Graceffa, Rita; Irving, Thomas C.; Nagarkar, Vivek V.

    2013-01-01

    There are a growing number of high brightness synchrotron sources that require high-frame-rate detectors to provide the time-scales required for performing time-resolved diffraction experiments. We report on the development of a very high frame rate CMOS X-ray detector for time-resolved muscle diffraction and time-resolved solution scattering experiments. The detector is based on a low-afterglow scintillator, provides a megapixel resolution with frame rates of up to 120,000 frames per second, an effective pixel size of 64 µm, and can be adapted for various X-ray energies. The paper describes the detector design and initial results of time-resolved diffraction experiments on a synchrotron beamline. PMID:24489595

  9. Millifluidics for Chemical Synthesis and Time-resolved Mechanistic Studies

    PubMed Central

    Krishna, Katla Sai; Biswas, Sanchita; Navin, Chelliah V.; Yamane, Dawit G.; Miller, Jeffrey T.; Kumar, Challa S.S.R.

    2013-01-01

    Procedures utilizing millifluidic devices for chemical synthesis and time-resolved mechanistic studies are described by taking three examples. In the first, synthesis of ultra-small copper nanoclusters is described. The second example provides their utility for investigating time resolved kinetics of chemical reactions by analyzing gold nanoparticle formation using in situ X-ray absorption spectroscopy. The final example demonstrates continuous flow catalysis of reactions inside millifluidic channel coated with nanostructured catalyst. PMID:24327099

  10. The ULTRA Laser System—For Time-Resolved Spectroscopy

    NASA Astrophysics Data System (ADS)

    Parker, Anthony

    2010-08-01

    Time-resolved vibrational spectroscopy (TRVS) has many unique features and capabilities for elucidating the structural changes of transient species across the fs to ms time frame. The recently developed 10 KHz, 10W ULTRA laser system represents the very latest technology. ULTRA's performance and capabilities will be described for the time resolved infrared, 2D infrared and femtosecond stimulated Raman spectroscopy techniques with examples taken from organometallic intermediates, organic excited states and DNA tertiary structure.

  11. Seventh international conference on time-resolved vibrational spectroscopy

    SciTech Connect

    Dyer, R.B.; Martinez, M.A.D.; Shreve, A.; Woodruff, W.H.

    1997-04-01

    The International Conference on Time-Resolved Vibrational Spectroscopy (TRVS) is widely recognized as the major international forum for the discussion of advances in this rapidly growing field. The 1995 conference was the seventh in a series that began at Lake Placid, New York, 1982. Santa Fe, New Mexico, was the site of the Seventh International Conference on Time-Resolved Vibrational Spectroscopy, held from June 11 to 16, 1995. TRVS-7 was attended by 157 participants from 16 countries and 85 institutions, and research ranging across the full breadth of the field of time-resolved vibrational spectroscopy was presented. Advances in both experimental capabilities for time-resolved vibrational measurements and in theoretical descriptions of time-resolved vibrational methods continue to occur, and several sessions of the conference were devoted to discussion of these advances and the associated new directions in TRVS. Continuing the interdisciplinary tradition of the TRVS meetings, applications of time-resolved vibrational methods to problems in physics, biology, materials science, and chemistry comprised a large portion of the papers presented at the conference.

  12. Time-resolved neurite mechanics by thermal fluctuation assessments.

    PubMed

    Gárate, Fernanda; Betz, Timo; Pertusa, María; Bernal, Roberto

    2015-12-30

    In the absence of simple noninvasive measurements, the knowledge of temporal and spatial variations of axons mechanics remains scarce. By extending thermal fluctuation spectroscopy (TFS) to long protrusions, we determine the transverse amplitude thermal fluctuation spectra that allow direct and simultaneous access to three key mechanics parameters: axial tension, bending flexural rigidity and plasma membrane tension. To test our model, we use PC12 cell protrusions-a well-know biophysical model of axons-in order to simplify the biological system under scope. For instance, axial and plasma membrane tension are found in the range of nano Newton and tens of pico Newtons per micron respectively. Furthermore, our results shows that the TFS technique is capable to distinguish quasi-identical protrusions. Another advantage of our approach is the time resolved nature of the measurements. Indeed, in the case of long term experiments on PC12 protrusions, TFS has revealed large temporal, correlated variations of the protrusion mechanics, displaying extraordinary feedback control over the axial tension in order to maintain a constant tension value.

  13. A Multi-Enzyme Bioluminescent Time-Resolved Pyrophosphate Assay

    PubMed Central

    Sun, Ye; Jacobson, K. Bruce; Golovlev, Val

    2009-01-01

    We have developed a high-sensitivity assay for measurement of inorganic pyrophosphate (PPi) in adenosine 5′-triphosphate (ATP) contaminated samples. The assay is based on time-resolved measurements of the luminescence kinetics and implements multiple enzymes to convert PPi to ATP that is, in turn, utilized to produce light; and to hydrolyze PPi for measurement of the steady-state background luminescence. A theoretical model for describing luminescence kinetics and optimizing composition of the assay detection mixture is presented. We found the model is in excellent agreement with the experimental results. We have developed and evaluated two algorithms for PPi measurement from luminescence kinetics acquired from ATP-contaminated samples. The first algorithm is considered to be the method of choice for analysis of long, i.e., 3-5 min, kinetics. The activity of enzymes is controlled during the experiment; the sensitivity of PPi detection is about 7 pg/ml or 15 pM of PPi in ATP-contaminated samples. The second algorithm is designed for analysis of short, i.e., less than 1-min luminescence kinetics. It has about 20 pM PPi detection sensitivity and may be the better choice for assays in microplate format, where a short measurement time is required. The PPi assay is primarily developed for RNA expression analysis, but it also can be used in various applications, which require high sensitivity PPi detection in ATP-contaminated samples. PMID:17540325

  14. Time-resolved neutron imaging at ANTARES cold neutron beamline

    NASA Astrophysics Data System (ADS)

    Tremsin, A. S.; Dangendorf, V.; Tittelmeier, K.; Schillinger, B.; Schulz, M.; Lerche, M.; Feller, W. B.

    2015-07-01

    In non-destructive evaluation with X-rays light elements embedded in dense, heavy (or high-Z) matrices show little contrast and their structural details can hardly be revealed. Neutron radiography, on the other hand, provides a solution for those cases, in particular for hydrogenous materials, owing to the large neutron scattering cross section of hydrogen and uncorrelated dependency of neutron cross section on the atomic number. The majority of neutron imaging experiments at the present time is conducted with static objects mainly due to the limited flux intensity of neutron beamline facilities and sometimes due to the limitations of the detectors. However, some applications require the studies of dynamic phenomena and can now be conducted at several high intensity beamlines such as the recently rebuilt ANTARES beam line at the FRM-II reactor. In this paper we demonstrate the capabilities of time resolved imaging for repetitive processes, where different phases of the process can be imaged simultaneously and integrated over multiple cycles. A fast MCP/Timepix neutron counting detector was used to image the water distribution within a model steam engine operating at 10 Hz frequency. Within <10 minutes integration the amount of water was measured as a function of cycle time with a sub-mm spatial resolution, thereby demonstrating the capabilities of time-resolved neutron radiography for the future applications. The neutron spectrum of the ANTARES beamline as well as transmission spectra of a Fe sample were also measured with the Time Of Flight (TOF) technique in combination with a high resolution beam chopper. The energy resolution of our setup was found to be ~ 0.8% at 5 meV and ~ 1.7% at 25 meV. The background level (most likely gammas and epithermal/fast neutrons) of the ANTARES beamline was also measured in our experiments and found to be on the scale of 3% when no filters are installed in the beam. Online supplementary data available from stacks.iop.org/jinst/10

  15. Average 3-dimensional models for the comparison of Orbscan II and Pentacam pachymetry maps in normal corneas.

    PubMed

    Bourges, Jean-Louis; Alfonsi, Nicolas; Laliberté, Jean-François; Chagnon, Miguel; Renard, Gilles; Legeais, Jean-Marc; Brunette, Isabelle

    2009-11-01

    To assess the reliability of Orbscan (Bausch & Lomb, Salt Lake City, UT) and Pentacam (Oculus, Wetzlar, Germany) central corneal thickness (CCT) and peripheral corneal thickness (PCT) measurements based on 2 methodologies. Evaluation of a diagnostic technology. Thirty healthy volunteers were recruited prospectively at the Department of Ophthalmology of the Hôtel-Dieu Hospital, Paris, France. Central corneal thickness and PCT were assessed, using ultrasound pachymetry (USP) as the gold standard. Two methodologies were used: (1) the traditional analysis of pachymetry data from 1 central and 8 peripheral reference positions on the cornea, and (2) a 3-dimensional (3-D) analysis based on average corneal pachymetry maps constructed for each system (Orbscan, Pentacam, and USP), each operator (operators 1 and 2), and each visit (visits A and B). Repeatability, intersystem reproducibility, interoperator reproducibility, reproducibility over time, and accuracy of Orbscan and Pentacam CCT and PCT measurements. Distribution and statistical significance of the differences between 3-D average maps. Repeatability (Orbscan intraclass correlation coefficients [ICCs], 0.967-0.992; Pentacam ICCs, 0.986-0.997), interoperator reproducibility, and reproducibility over time (ICCs, 0.976-0.997) were excellent to almost perfect for both systems. Intersystem agreement was almost perfect for CCT (ICC, 0.980), but less strong for PCT (ICCs, 0.928-0.979). Despite a good to excellent agreement between the optical systems and USP (ICCs, 0.608-0.958), USP CCT readings were thicker (mean difference, up to 15.2 microm; P<0.05), and USP PCT readings were thinner (P<0.05). Orbscan and Pentacam average maps allowed comprehensive interpretation of differences between populations according to the magnitude, distribution, and statistical significance, minimizing the risk of giving excessive weight to few data measured at specific locations on the cornea. Both methodologies showed that Orbscan and

  16. Time resolved strain dependent morphological study of electrically conducting nanocomposites

    NASA Astrophysics Data System (ADS)

    Khan, Imran; Mitchell, Geoffrey; Mateus, Artur; Kamma-Lorger, Christina S.

    2015-10-01

    An efficient and reliable method is introduced to understand the network behaviour of nano-fillers in a polymeric matrix under uniaxial strain coupled with small angle x-ray scattering measurements. The nanoparticles (carbon nanotubes) are conductive and the particles form a percolating network that becomes apparent source of electrical conduction and consequently the samples behave as a bulk conductor. Polyurethane based nanocomposites containing 2% w/w multiwall carbon nanotubes are studied. The electrical conductivity of the nanocomposite was (3.28×10-5s/m).The sample was able to be extended to an extension ratio of 1.7 before fracture. A slight variation in the electrical conductivity is observed under uniaxial strain which we attribute to the disturbance of conductive pathways. Further, this work is coupled with in- situ time resolved small angle x-ray scattering measurements using a synchrotron beam line to enable its measurements to be made during the deformation cycle. We use a multiscale structure to model the small angle x-ray data. The results of the analysis are interpreted as the presence of aggregates which would also go some way towards understanding why there is no alignment of the carbon nanotubes.

  17. Synchronized multiartifact reduction with tomographic reconstruction (SMART-RECON): A statistical model based iterative image reconstruction method to eliminate limited-view artifacts and to mitigate the temporal-average artifacts in time-resolved CT

    PubMed Central

    Chen, Guang-Hong; Li, Yinsheng

    2015-01-01

    Purpose: In x-ray computed tomography (CT), a violation of the Tuy data sufficiency condition leads to limited-view artifacts. In some applications, it is desirable to use data corresponding to a narrow temporal window to reconstruct images with reduced temporal-average artifacts. However, the need to reduce temporal-average artifacts in practice may result in a violation of the Tuy condition and thus undesirable limited-view artifacts. In this paper, the authors present a new iterative reconstruction method, synchronized multiartifact reduction with tomographic reconstruction (SMART-RECON), to eliminate limited-view artifacts using data acquired within an ultranarrow temporal window that severely violates the Tuy condition. Methods: In time-resolved contrast enhanced CT acquisitions, image contrast dynamically changes during data acquisition. Each image reconstructed from data acquired in a given temporal window represents one time frame and can be denoted as an image vector. Conventionally, each individual time frame is reconstructed independently. In this paper, all image frames are grouped into a spatial–temporal image matrix and are reconstructed together. Rather than the spatial and/or temporal smoothing regularizers commonly used in iterative image reconstruction, the nuclear norm of the spatial–temporal image matrix is used in SMART-RECON to regularize the reconstruction of all image time frames. This regularizer exploits the low-dimensional structure of the spatial–temporal image matrix to mitigate limited-view artifacts when an ultranarrow temporal window is desired in some applications to reduce temporal-average artifacts. Both numerical simulations in two dimensional image slices with known ground truth and in vivo human subject data acquired in a contrast enhanced cone beam CT exam have been used to validate the proposed SMART-RECON algorithm and to demonstrate the initial performance of the algorithm. Reconstruction errors and temporal fidelity

  18. Synchronized multiartifact reduction with tomographic reconstruction (SMART-RECON): A statistical model based iterative image reconstruction method to eliminate limited-view artifacts and to mitigate the temporal-average artifacts in time-resolved CT.

    PubMed

    Chen, Guang-Hong; Li, Yinsheng

    2015-08-01

    In x-ray computed tomography (CT), a violation of the Tuy data sufficiency condition leads to limited-view artifacts. In some applications, it is desirable to use data corresponding to a narrow temporal window to reconstruct images with reduced temporal-average artifacts. However, the need to reduce temporal-average artifacts in practice may result in a violation of the Tuy condition and thus undesirable limited-view artifacts. In this paper, the authors present a new iterative reconstruction method, synchronized multiartifact reduction with tomographic reconstruction (SMART-RECON), to eliminate limited-view artifacts using data acquired within an ultranarrow temporal window that severely violates the Tuy condition. In time-resolved contrast enhanced CT acquisitions, image contrast dynamically changes during data acquisition. Each image reconstructed from data acquired in a given temporal window represents one time frame and can be denoted as an image vector. Conventionally, each individual time frame is reconstructed independently. In this paper, all image frames are grouped into a spatial-temporal image matrix and are reconstructed together. Rather than the spatial and/or temporal smoothing regularizers commonly used in iterative image reconstruction, the nuclear norm of the spatial-temporal image matrix is used in SMART-RECON to regularize the reconstruction of all image time frames. This regularizer exploits the low-dimensional structure of the spatial-temporal image matrix to mitigate limited-view artifacts when an ultranarrow temporal window is desired in some applications to reduce temporal-average artifacts. Both numerical simulations in two dimensional image slices with known ground truth and in vivo human subject data acquired in a contrast enhanced cone beam CT exam have been used to validate the proposed SMART-RECON algorithm and to demonstrate the initial performance of the algorithm. Reconstruction errors and temporal fidelity of the reconstructed

  19. Synchronized multiartifact reduction with tomographic reconstruction (SMART-RECON): A statistical model based iterative image reconstruction method to eliminate limited-view artifacts and to mitigate the temporal-average artifacts in time-resolved CT

    SciTech Connect

    Chen, Guang-Hong; Li, Yinsheng

    2015-08-15

    Purpose: In x-ray computed tomography (CT), a violation of the Tuy data sufficiency condition leads to limited-view artifacts. In some applications, it is desirable to use data corresponding to a narrow temporal window to reconstruct images with reduced temporal-average artifacts. However, the need to reduce temporal-average artifacts in practice may result in a violation of the Tuy condition and thus undesirable limited-view artifacts. In this paper, the authors present a new iterative reconstruction method, synchronized multiartifact reduction with tomographic reconstruction (SMART-RECON), to eliminate limited-view artifacts using data acquired within an ultranarrow temporal window that severely violates the Tuy condition. Methods: In time-resolved contrast enhanced CT acquisitions, image contrast dynamically changes during data acquisition. Each image reconstructed from data acquired in a given temporal window represents one time frame and can be denoted as an image vector. Conventionally, each individual time frame is reconstructed independently. In this paper, all image frames are grouped into a spatial–temporal image matrix and are reconstructed together. Rather than the spatial and/or temporal smoothing regularizers commonly used in iterative image reconstruction, the nuclear norm of the spatial–temporal image matrix is used in SMART-RECON to regularize the reconstruction of all image time frames. This regularizer exploits the low-dimensional structure of the spatial–temporal image matrix to mitigate limited-view artifacts when an ultranarrow temporal window is desired in some applications to reduce temporal-average artifacts. Both numerical simulations in two dimensional image slices with known ground truth and in vivo human subject data acquired in a contrast enhanced cone beam CT exam have been used to validate the proposed SMART-RECON algorithm and to demonstrate the initial performance of the algorithm. Reconstruction errors and temporal fidelity

  20. Protein-ligand interactions probed by time-resolved crystallography

    SciTech Connect

    Schmidt, M.; Ihee, H.; Pahl, R.; Srajer, V.

    2005-03-09

    Time-resolved (TR) crystallography is a unique method for determining the structures of intermediates in biomolecular reactions. The technique reached its mature stage with the development of the powerful third-generation synchrotron X-ray sources, and the advances in data processing and analysis of time-resolved Laue crystallographic data. A time resolution of 100 ps has been achieved and relatively small structural changes can be detected even from only partial reaction initiation. The remaining challenge facing the application of this technique to a broad range of biological systems is to find an efficient and rapid, system-specific method for the reaction initiation in the crystal. Other frontiers for the technique involve the continued improvement in time resolution and further advances in methods for determining intermediate structures and reaction mechanisms. The time-resolved technique, combined with trapping methods and computational approaches, holds the promise for a complete structure-based description of biomolecular reactions.

  1. A time-resolved image sensor for tubeless streak cameras

    NASA Astrophysics Data System (ADS)

    Yasutomi, Keita; Han, SangMan; Seo, Min-Woong; Takasawa, Taishi; Kagawa, Keiichiro; Kawahito, Shoji

    2014-03-01

    This paper presents a time-resolved CMOS image sensor with draining-only modulation (DOM) pixels for tube-less streak cameras. Although the conventional streak camera has high time resolution, the device requires high voltage and bulky system due to the structure with a vacuum tube. The proposed time-resolved imager with a simple optics realize a streak camera without any vacuum tubes. The proposed image sensor has DOM pixels, a delay-based pulse generator, and a readout circuitry. The delay-based pulse generator in combination with an in-pixel logic allows us to create and to provide a short gating clock to the pixel array. A prototype time-resolved CMOS image sensor with the proposed pixel is designed and implemented using 0.11um CMOS image sensor technology. The image array has 30(Vertical) x 128(Memory length) pixels with the pixel pitch of 22.4um. .

  2. Time-Resolved Bandgap Reflectivity of Photoexcited Cadmium-Selenium

    NASA Astrophysics Data System (ADS)

    Frigo, Nicholas John

    The first time-resolved bandgap reflectivity measurements of CdSe are presented. The time resolution was in the ten picosecond range and was attained by using a two-pulse pump-probe technique. Carriers were created by the absorption of the pump pulse and the reflectivity of the probe pulse was measured as a function of the probe's wavelength and its time delay relative to the pump. Specifically, the excitonic reflectivity was the feature monitored in these experiments. In order to perform the experiments, a new type of two-wavelength picosecond dye laser was developed. Its novel intersecting cavity configuration permitted the high flux levels, wide tuning range, spectral location, and pulse synchronization needed for creating high electron -hole densities and measuring the reflectivity near the bandgap of CdSe. The reflectivity results were surprising. A rapid recovery of the screened excitonic reflectivity was seen that was unanticipated by earlier experimental results and theoretical estimates. Attempts to explain the data by electron-hole liquid formation, surface recombination, or bimolecular recombination were unable to agree with the data. To explain the unusual speed of the recovery a model was developed which emphasized carrier diffusion against impurity scattering. The carrier diffusion model gave estimates of the recovery time in substantial agreement with the reflectivity measurements. In addition, the model's predictions agreed well with a wide range of other reported experiments ranging from picosecond to nanosecond time scales in CdS, CdSe, and GaAs using gain and luminescence measurements. Approximate solutions in closed form were presented that duplicated the major features of the model. Preliminary evidence against electron-hole liquid formation was presented; a low power experiment failed to give the expected signature. This result is unexpected since the temperature of these experiments is estimated to be lower than the temperature of the

  3. Solving the Structure of Reaction Intermediates by Time-Resolved Synchrotron X-ray Absorption Spectroscopy

    SciTech Connect

    Wang, Q.; Hanson, J; Frenkel, A

    2008-01-01

    We present a robust data analysis method of time-resolved x-ray absorption spectroscopy experiments suitable for chemical speciation and structure determination of reaction intermediates. Chemical speciation is done by principal component analysis (PCA) of the time-resolved x-ray absorption near-edge structure data. Structural analysis of intermediate phases is done by theoretical modeling of their extended x-ray absorption fine-structure data isolated by PCA. The method is demonstrated using reduction and reoxidation of Cu-doped ceria catalysts where we detected reaction intermediates and measured fine details of the reaction kinetics. This approach can be directly adapted to many time-resolved x-ray spectroscopy experiments where new rapid throughput data collection and analysis methods are needed.

  4. Spatially resolved and time-resolved imaging of transport of indirect excitons in high magnetic fields

    NASA Astrophysics Data System (ADS)

    Dorow, C. J.; Hasling, M. W.; Calman, E. V.; Butov, L. V.; Wilkes, J.; Campman, K. L.; Gossard, A. C.

    2017-06-01

    We present the direct measurements of magnetoexciton transport. Excitons give the opportunity to realize the high magnetic-field regime for composite bosons with magnetic fields of a few tesla. Long lifetimes of indirect excitons allow the study of kinetics of magnetoexciton transport with time-resolved optical imaging of exciton photoluminescence. We performed spatially, spectrally, and time-resolved optical imaging of transport of indirect excitons in high magnetic fields. We observed that an increasing magnetic field slows down magnetoexciton transport. The time-resolved measurements of the magnetoexciton transport distance allowed for an experimental estimation of the magnetoexciton diffusion coefficient. An enhancement of the exciton photoluminescence energy at the laser excitation spot was found to anticorrelate with the exciton transport distance. A theoretical model of indirect magnetoexciton transport is presented and is in agreement with the experimental data.

  5. Time-Resolved X-Ray Crystallography of Heme Proteins

    SciTech Connect

    Srajer, Vukica; Royer, Jr., William E.

    2008-04-29

    Heme proteins, with their natural photosensitivity, are excellent systems for the application of time-resolved crystallographic methods. Ligand dissociation can be readily initiated by a short laser pulse with global structural changes probed at the atomic level by X-rays in real time. Third-generation synchrotrons provide 100-ps X-ray pulses of sufficient intensity for monitoring very fast processes. Successful application of such time-resolved crystallographic experiments requires that the structural changes being monitored are compatible with the crystal lattice. These techniques have recently permitted observing for the first time allosteric transitions in real time for a cooperative dimeric hemoglobin.

  6. Time-resolved x-ray crystallography of heme proteins

    PubMed Central

    Royer, William E.

    2012-01-01

    Heme proteins, with their natural photosensitivity, are excellent systems for the application of time-resolved crystallographic methods. Ligand dissociation can be readily initiated by a short laser pulse with global structural changes probed at the atomic level by X-rays in real time. Third generation synchrotrons provide 100ps X-ray pulses of sufficient intensity for monitoring very fast processes. Successful application of such time-resolved crystallographic experiments requires that the structural changes being monitored are compatible with the crystal lattice. These techniques have permitted observing allosteric transitions in real time for a cooperative dimeric hemoglobin. PMID:18433638

  7. Time-resolved photon emission from layered turbid media

    NASA Astrophysics Data System (ADS)

    Hielscher, Andreas H.; Liu, Hanli; Chance, Britton; Tittel, Frank K.; Jacques, Steven L.

    1996-02-01

    We present numerical and experimental results of time-resolved emission profiles from various layered turbid media. Numerical solutions determined by time-resolved Monte Carlo simulations are compared with measurements on layered-tissue phantoms made from gelatin. In particular, we show that in certain cases the effects of the upper layers can be eliminated. As a practical example, these results are used to analyze in vivo measurements on the human head. This demonstrates the influence of skin, skull, and meninges on the determination of the blood oxygenation in the brain.

  8. Time-resolved photon emission from layered turbid media

    SciTech Connect

    Hielscher, A.H.; Liu, H.; Chance, B.; Tittel, F.K.; Jacques, S.L.

    1996-02-01

    We present numerical and experimental results of time-resolved emission profiles from various layered turbid media. Numerical solutions determined by time-resolved Monte Carlo simulations are compared with measurements on layered-tissue phantoms made from gelatin. In particular, we show that in certain cases the effects of the upper layers can be eliminated. As a practical example, these results are used to analyze {ital in} {ital vivo} measurements on the human head. This demonstrates the influence of skin, skull, and meninges on the determination of the blood oxygenation in the brain. {copyright} {ital 1996 Optical Society of America.}

  9. Monte Carlo algorithm for efficient simulation of time-resolved fluorescence in layered turbid media.

    PubMed

    Liebert, A; Wabnitz, H; Zołek, N; Macdonald, R

    2008-08-18

    We present an efficient Monte Carlo algorithm for simulation of time-resolved fluorescence in a layered turbid medium. It is based on the propagation of excitation and fluorescence photon bundles and the assumption of equal reduced scattering coefficients at the excitation and emission wavelengths. In addition to distributions of times of arrival of fluorescence photons at the detector, 3-D spatial generation probabilities were calculated. The algorithm was validated by comparison with the analytical solution of the diffusion equation for time-resolved fluorescence from a homogeneous semi-infinite turbid medium. It was applied to a two-layered model mimicking intra- and extracerebral compartments of the adult human head.

  10. Real-time acquisition of transendothelial electrical resistance in an all-human, in vitro, 3-dimensional, blood-brain barrier model exemplifies tight-junction integrity.

    PubMed

    Maherally, Zaynah; Fillmore, Helen L; Tan, Sim Ling; Tan, Suk Fei; Jassam, Samah A; Quack, Friederike I; Hatherell, Kathryn E; Pilkington, Geoffrey J

    2017-09-07

    The blood-brain barrier (BBB) consists of endothelial cells, astrocytes, and pericytes embedded in basal lamina (BL). Most in vitro models use nonhuman, monolayer cultures for therapeutic-delivery studies, relying on transendothelial electrical resistance (TEER) measurements without other tight-junction (TJ) formation parameters. We aimed to develop reliable, reproducible, in vitro 3-dimensional (3D) models incorporating relevant human, in vivo cell types and BL proteins. The 3D BBB models were constructed with human brain endothelial cells, human astrocytes, and human brain pericytes in mono-, co-, and tricultures. TEER was measured in 3D models using a volt/ohmmeter and cellZscope. Influence of BL proteins-laminin, fibronectin, collagen type IV, agrin, and perlecan-on adhesion and TEER was assessed using an electric cell-substrate impedance-sensing system. TJ protein expression was assessed by Western blotting (WB) and immunocytochemistry (ICC). Perlecan (10 µg/ml) evoked unreportedly high, in vitro TEER values (1200 Ω) and the strongest adhesion. Coculturing endothelial cells with astrocytes yielded the greatest resistance over time. ICC and WB results correlated with resistance levels, with evidence of prominent occludin expression in cocultures. BL proteins exerted differential effects on TEER, whereas astrocytes in contact yielded higher TEER values and TJ expression.-Maherally, Z., Fillmore, H. L., Tan, S. L., Tan, S. F., Jassam, S. A., Quack, F. I., Hatherell, K. E., Pilkington, G. J. Real-time acquisition of transendothelial electrical resistance in an all-human, in vitro, 3-dimensional, blood-brain barrier model exemplifies tight-junction integrity. © FASEB.

  11. Time-Resolved Emission Spectroscopy of Field Reversed Configuration Thruster

    DTIC Science & Technology

    2016-08-31

    Field Reversed Configuration (FRC) thrusters are candidates for next generation high -powered electric propulsion (EP) • Advantages over competing...16468 Introduction • Field Reversed Configuration (FRC) thrusters are candidates for next generation high -powered electric propulsion (EP) • Advantages...Briefing Charts 3. DATES COVERED (From - To) 06 September 2016 - 01 November 2016 4. TITLE AND SUBTITLE Time-Resolved Emission Spectroscopy of Field

  12. Time-resolved imaging of cavitation effects during laser lithotripsy

    NASA Astrophysics Data System (ADS)

    Siano, Salvatore; Pini, Roberto; Salimbeni, Renzo; Vannini, Matteo

    1995-01-01

    We devised a diagnostic technique based on a pump-and-probe scheme that provided time- resolved imaging of photofragmentation effects during laser lithotripsy. The evolution of the cavitation bubble induced on kidney stone samples by underwater irradiation with a XeCl excimer laser is presented and analyzed.

  13. 3DHYDROGEOCHEM: A 3-DIMENSIONAL MODEL OF DENSITY-DEPENDENT SUBSURFACE FLOW AND THERMAL MULTISPECIES-MULTICOMPONENT HYDROGEOCHEMICAL TRANSPORT

    EPA Science Inventory

    This report presents a three-dimensional finite-element numerical model designed to simulate chemical transport in subsurface systems with temperature effect taken into account. The three-dimensional model is developed to provide (1) a tool of application, with which one is able...

  14. 3DHYDROGEOCHEM: A 3-DIMENSIONAL MODEL OF DENSITY-DEPENDENT SUBSURFACE FLOW AND THERMAL MULTISPECIES-MULTICOMPONENT HYDROGEOCHEMICAL TRANSPORT

    EPA Science Inventory

    This report presents a three-dimensional finite-element numerical model designed to simulate chemical transport in subsurface systems with temperature effect taken into account. The three-dimensional model is developed to provide (1) a tool of application, with which one is able...

  15. User's manual for master: Modeling of aerodynamic surfaces by 3-dimensional explicit representation. [input to three dimensional computational fluid dynamics

    NASA Technical Reports Server (NTRS)

    Gibson, S. G.

    1983-01-01

    A system of computer programs was developed to model general three dimensional surfaces. Surfaces are modeled as sets of parametric bicubic patches. There are also capabilities to transform coordinates, to compute mesh/surface intersection normals, and to format input data for a transonic potential flow analysis. A graphical display of surface models and intersection normals is available. There are additional capabilities to regulate point spacing on input curves and to compute surface/surface intersection curves. Input and output data formats are described; detailed suggestions are given for user input. Instructions for execution are given, and examples are shown.

  16. Mid-infrared time-resolved photoconduction in black phosphorus

    NASA Astrophysics Data System (ADS)

    Suess, Ryan J.; Leong, Edward; Garrett, Joseph L.; Zhou, Tong; Salem, Reza; Munday, Jeremy N.; Murphy, Thomas E.; Mittendorff, Martin

    2016-12-01

    Black phosphorus has attracted interest as a material for use in optoelectronic devices due to many favorable properties such as a high carrier mobility, field-effect, and a direct bandgap that can range from 0.3 eV in its bulk crystalline form to 1.7-2.0 eV for a single atomic layer. The low bandgap energy for multilayer black phosphorus consisting of more than approximately five atomic layers allows for direct transition photoabsorption that enables detection of light out to mid-infrared frequencies. In this work, we characterize the room temperature optical response of a black phosphorus photoconductive detector at wavelengths ranging from 1.56 to 3.75 μm. Pulsed autocorrelation measurements in the near-infrared regime reveal a strong, sub-linear photocurrent nonlinearity with a response time of 1 ns, indicating that gigahertz electrical bandwidth is feasible. Time resolved photoconduction measurements covering near- and mid-infrared frequencies show a fast 65 ps rise time, followed by a carrier relaxation with a time scale that matches the intrinsic limit determined by autocorrelation. The sublinear photoresponse is shown to be caused by a reduction in the carrier relaxation time as more energy is absorbed in the black phosphorus flake and is well described by a carrier recombination model that is nonlinear with excess carrier density. The device exhibits a measured noise-equivalent power of 530 pW Hz-1/2, which is the value expected for Johnson noise limited performance. The fast and sensitive room temperature photoresponse demonstrates that black phosphorus is a promising new material for mid-infrared optoelectronics.

  17. Time-resolved diagnostics for concrete target response

    SciTech Connect

    Baum, D.W.; Kuklo, R.M.; Reaugh, J.E.; Simonson, S.C.

    1996-05-01

    In order to facilitate the design of advanced penetrating weapons for defeating land targets, the interaction of concrete with high-velocity penetrators needs to be better characterized. To aid in this effort, three new types of time-resolved diagnostics are being developed and have been used in two experiments and one demonstration: fiber optic arrays to localize penetrators in space and time, Fabry-Perot velocimetry to record the concrete particle velocity, which is related to the pressure, at specific locations within concrete targets, and micropower impulse radar to provide a non-intrusive measure of the penetrator position-time history in a target. The two experiments used the fiber optic array and the Fabry-Perot velocimeter to diagnose the response of concrete to penetration by a Viper shaped charge jet. The results were analyzed using the CALE continuum mechanics simulation program, for which a preliminary model of the material properties of concrete was developed. The fiber optic arrays recorded the bow shock at locations 6.4 and 16.9 cm from the front surfaces. The Fabry-Perot velocimeter measured a free-surface velocity of 0.13 km/s at a distance of 3 cm and obliquity 70{degree} from the jet, which was moving at an interface velocity of 4.0 km/s at a depth of 29 cm. These values imply a pressure of about 6.6 kbar at that location. The demonstration used micropower impulse radar with a pulse repetition frequency of 0.25 MHz and a cell size of 30 ps to detect and record the motion of a metal penetrator simulant moving inside a cylindrical concrete target.

  18. The use of TOUGH2 for the LBL/USGS 3-dimensional site-scale model of Yucca Mountain, Nevada

    SciTech Connect

    Bodvarsson, G.; Chen, G.; Haukwa, C.

    1995-03-01

    The three-dimensional site-scale numerical model of the unsaturated zone at Yucca Mountain is under continuous development and calibration through a collaborative effort between Lawrence Berkeley Laboratory (LBL) and the United States Geological Survey (USGS). The site-scale model covers an area of about 30 km{sup 2} and is bounded by major fault zones to the west (Solitario Canyon Fault), east (Bow Ridge Fault) and perhaps to the north by an unconfirmed fault (Yucca Wash Fault). The model consists of about 5,000 grid blocks (elements) with nearly 20,000 connections between them the grid was designed to represent the most prevalent geological and hydro-geological features of the site including major faults, and layering and bedding of the hydro-geological units. Further information about the three-dimensional site-scale model is given by Wittwer et al. and Bodvarsson et al.

  19. Next Generation, Waveform Based 3-Dimensional Models & Metrics to Improve Nuclear Explosion Monitoring in the Middle East

    DTIC Science & Technology

    2012-04-20

    Indian tectonic plates . Without knowing the true lateral changes in anisotropy and including large continental provinces within the model it is...between recordings of seismic waves traversing the region from Tibet to the Red Sea compared to synthetics from the current iteration model is the...also significantly increase anomaly strength while sharpening the anomaly edges to create stronger and more pronounced tectonic structures. The

  20. Modified flapless dental implant surgery for planning treatment in a maxilla including sinus lift augmentation through use of virtual surgical planning and a 3-dimensional model.

    PubMed

    Nikzad, Sakineh; Azari, Abbas; Ghassemzadeh, Amanollah

    2010-09-01

    The concept of "prosthetic-driven implantology" may be considered a turning point in the history of modern dental implantology. On the basis of this sophisticated approach, the available bone and the optimal prosthetic position of the future restoration are checked before surgical intervention. However, the major drawback of today's prosthodontic discipline is that it is inherently 2-dimensional in nature, which may prevent the appropriate treatment; this problem can be overcome by the 3-dimensional capability of a computer-assisted approach when performed judiciously. It was proposed that this technique has the potential to provide a high level of safety and accuracy in comparison to traditional surgical procedures. Using a novel approach, we performed modified flapless implant surgery accompanied by a simultaneous sinus-lifting procedure. The technique used a 3-dimensional life-sized computer-aided design/computer-aided manufacturing (CAD/CAM) model prepared from the computed tomography images for prosthetic/surgical diagnosis and treatment planning. The procedure of implant planning, model surgery, and sinus floor augmentation in this sophisticated flapless surgical approach has the potential to provide substantial benefits for both patients and practitioners. The versatility of the described technique not only allows more accurate implementation of the treatment plan to the patient's mouth but also may offer many additional significant benefits, including the use of custom surgical guides, life-sized bone model manipulation, and surgical rehearsal, all of which are very difficult to achieve with current traditional procedures. Copyright 2010 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

  1. Scan, plan, print, practice, perform: Development and use of a patient-specific 3-dimensional printed model in adult cardiac surgery.

    PubMed

    Hermsen, Joshua L; Burke, Thomas M; Seslar, Stephen P; Owens, David S; Ripley, Beth A; Mokadam, Nahush A; Verrier, Edward D

    2017-01-01

    Static 3-dimensional printing is used for operative planning in cases that involve difficult anatomy. An interactive 3D print allowing deliberate surgical practice would represent an advance. Two patients with hypertrophic cardiomyopathy had 3-dimensional prints constructed preoperatively. Stereolithography files were generated by segmentation of chest computed tomographic scans. Prints were made with hydrogel material, yielding tissue-like models that can be surgically manipulated. Septal myectomy of the print was performed preoperatively in the simulation laboratory. Volumetric measures of print and patient resected specimens were compared. An assessment tool was developed and used to rate the utility of this process. Clinical and echocardiographic data were reviewed. There was congruence between volumes of print and patient resection specimens (patient 1, 3.5 cm(3) and 3.0 cm(3), respectively; patient 2, 4.0 cm(3) and 4.0 cm(3), respectively). The prints were rated useful (3.5 and 3.6 on a 5-point Likert scale) for preoperative visualization, planning, and practice. Intraoperative echocardiographic assessment showed adequate relief of left ventricular outflow tract obstruction (patient 1, 80 mm Hg to 18 mm Hg; patient 2, 96 mm Hg to 9 mm Hg). Both patients reported symptomatic improvement (New York Heart Association functional class III to class I). Three-dimensional printing of interactive hypertrophic cardiomyopathy heart models allows for patient-specific preoperative simulation. Resection volume relationships were congruous on both specimens and suggest evidence of construct validity. This model also holds educational promise for simulation of a low-volume, high-risk operation that is traditionally difficult to teach. Copyright © 2016 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

  2. Direct measurement of the 3-dimensional DNA lesion distribution induced by energetic charged particles in a mouse model tissue

    PubMed Central

    Mirsch, Johanna; Tommasino, Francesco; Frohns, Antonia; Conrad, Sandro; Durante, Marco; Scholz, Michael; Friedrich, Thomas; Löbrich, Markus

    2015-01-01

    Charged particles are increasingly used in cancer radiotherapy and contribute significantly to the natural radiation risk. The difference in the biological effects of high-energy charged particles compared with X-rays or γ-rays is determined largely by the spatial distribution of their energy deposition events. Part of the energy is deposited in a densely ionizing manner in the inner part of the track, with the remainder spread out more sparsely over the outer track region. Our knowledge about the dose distribution is derived solely from modeling approaches and physical measurements in inorganic material. Here we exploited the exceptional sensitivity of γH2AX foci technology and quantified the spatial distribution of DNA lesions induced by charged particles in a mouse model tissue. We observed that charged particles damage tissue nonhomogenously, with single cells receiving high doses and many other cells exposed to isolated damage resulting from high-energy secondary electrons. Using calibration experiments, we transformed the 3D lesion distribution into a dose distribution and compared it with predictions from modeling approaches. We obtained a radial dose distribution with sub-micrometer resolution that decreased with increasing distance to the particle path following a 1/r2 dependency. The analysis further revealed the existence of a background dose at larger distances from the particle path arising from overlapping dose deposition events from independent particles. Our study provides, to our knowledge, the first quantification of the spatial dose distribution of charged particles in biologically relevant material, and will serve as a benchmark for biophysical models that predict the biological effects of these particles. PMID:26392532

  3. Time-resolved magnetic circular dichroism spectroscopy of photolyzed carbonmonoxy cytochrome c oxidase (cytochrome aa3).

    PubMed

    Goldbeck, R A; Dawes, T D; Einarsdóttir, O; Woodruff, W H; Kliger, D S

    1991-07-01

    Nanosecond time-resolved magnetic circular dichroism (TRMCD) and time-resolved natural circular dichroism (TRCD) measurements of photolysis products of the CO complex of eukaryotic cytochrome c oxidase (CcO-CO) are presented. TRMCD spectra obtained at 100 ns and 10 microseconds after photolysis are diagnostic of pentacoordinate cytochrome a3Fe2+, as would be expected for simple photodissociation. Other time-resolved spectroscopies (UV-visible and resonance Raman), however, show evidence for unusual Fea3(2+) coordination after CO photolysis (Woodruff, W. H., O. Einarsdóttir, R. B. Dyer, K. A. Bagley, G. Palmer, S. J. Atherton, R. A. Goldbeck, T. D. Dawes, and D. S. Kliger. 1991. Proc. Nat. Acad. Sci. U.S.A. 88:2588-2592). Furthermore, time-resolved IR experiments have shown that photodissociated CO binds to CuB+ prior to recombining with Fea3(2+) (Dyer, R. B., O. Einarsdóttir, P. M. Killough, J. J. López-Garriga, and W. H. Woodruff. 1989. J. Am. Chem. Soc. 111:7657-7659). A model of the CcO-CO photolysis cycle which is consistent with all of the spectroscopic results is presented. A novel feature of this model is the coordination of a ligand endogenous to the protein to the Fe axial site vacated by the photolyzed CO and the simultaneous breaking of the Fe-imidazole(histidine) bond.

  4. Time-resolved optical spectroscopy measurements of shocked liquid deuterium

    NASA Astrophysics Data System (ADS)

    Bailey, J. E.; Knudson, M. D.; Carlson, A. L.; Dunham, G. S.; Desjarlais, M. P.; Hanson, D. L.; Asay, J. R.

    2008-10-01

    Time-resolved optical spectroscopy has been used to measure the shock pressure steadiness, emissivity, and temperature of liquid deuterium shocked to 22-90 GPa. The shock was produced using magnetically accelerated flyer plate impact, and spectra were acquired with a suite of four fiber-optic-coupled spectrometers with streak camera detectors. The shock pressure changes by an average of -1.2% over the 10-30 ns cell transit time, determined from the relative changes in the shock front self-emission with time. The shock front reflectivity was measured from 5140Å and 5320Å laser light reflected from the D2 shock. The emissivity inferred from the reflectivity measurements was in reasonably good agreement with quantum molecular dynamics simulation predictions. The spectral radiance wavelength dependence was found to agree well (average normalized χ2=1.6 ) with a Planckian multiplied by the emissivity. The shock front temperature was determined from the emissivity and the wavelength-dependent shock self-emission. Thirty-seven temperature measurements spanning the 22-90 GPa range were accumulated. The large number of temperature measurements enables a comparison of the scatter in the data with expectations for a Gaussian distribution. This facilitates determination of uncertainties that incorporate both apparatus contributions and otherwise unquantified systematic effects that cause self-emission variations from one experiment to another. Agreement between temperatures determined from the absolute spectral radiance and from the relative shape of the spectrum further substantiates the absence of systematic biases. The weighted mean temperature uncertainties were as low as ±3-4% , enabling the discrimination between competing models for the D2 equation of state (EOS). The temperature results agree well with models that predict a maximum compression of ˜4.4 . Softer models that predict approximately sixfold compression are inconsistent with the data to a very high

  5. New 3-dimensional CFD modeling of CO2 and H2S simultaneous stripping from water within PVDF hollow fiber membrane contactor

    NASA Astrophysics Data System (ADS)

    Bahlake, Ahmad; Farivar, Foad; Dabir, Bahram

    2016-07-01

    In this paper a 3-dimensional modeling of simultaneous stripping of carbon dioxide (CO2) and hydrogen sulfide (H2S) from water using hollow fiber membrane made of polyvinylidene fluoride is developed. The water, containing CO2 and H2S enters to the membrane as feed. At the same time, pure nitrogen flow in the shell side of a shell and tube hollow fiber as the solvent. In the previous methods of modeling hollow fiber membranes just one of the membranes was modeled and the results expand to whole shell and tube system. In this research the whole hollow fiber shell and tube module is modeled to reduce the errors. Simulation results showed that increasing the velocity of solvent flow and decreasing the velocity of the feed are leads to increase in the system yield. However the effect of the feed velocity on the process is likely more than the influence of changing the velocity of the gaseous solvent. In addition H2S stripping has higher yield in comparison with CO2 stripping. This model is compared to the previous modeling methods and shows that the new model is more accurate. Finally, the effect of feed temperature is studied using response surface method and the operating conditions of feed temperature, feed velocity, and solvent velocity is optimized according to synergistic effects. Simulation results show that, in the optimum operating conditions the removal percentage of H2S and CO2 are 27 and 21 % respectively.

  6. Ultrafast time-resolved spectroscopy of xanthophylls at low temperature.

    PubMed

    Cong, Hong; Niedzwiedzki, Dariusz M; Gibson, George N; Frank, Harry A

    2008-03-20

    Many of the spectroscopic features and photophysical properties of xanthophylls and their role in energy transfer to chlorophyll can be accounted for on the basis of a three-state model. The characteristically strong visible absorption of xanthophylls is associated with a transition from the ground state S0 (1(1)Ag-) to the S2 (1(1)Bu+) excited state. The lowest lying singlet state denoted S1 (2(1)Ag-), is a state into which absorption from the ground state is symmetry forbidden. Ultrafast optical spectroscopic studies and quantum computations have suggested the presence of additional excited singlet states in the vicinity of S1 (2(1)Ag-) and S2 (1(1)Bu+). One of these is denoted S* and has been suggested in previous work to be associated with a twisted molecular conformation of the molecule in the S1 (2(1)Ag-) state. In this work, we present the results of a spectroscopic investigation of three major xanthophylls from higher plants: violaxanthin, lutein, and zeaxanthin. These molecules have systematically increasing extents of pi-electron conjugation from nine to eleven conjugated carbon-carbon double bonds. All-trans isomers of the molecules were purified by high-performance liquid chromatography (HPLC) and studied by steady-state and ultrafast time-resolved optical spectroscopy at 77 K. Analysis of the data using global fitting techniques has revealed the inherent spectral properties and ultrafast dynamics of the excited singlet states of each of the molecules. Five different global fitting models were tested, and it was found that the data are best explained using a kinetic model whereby photoexcitation results in the promotion of the molecule into the S2 (1(1)Bu+) state that subsequently undergoes decay to a vibrationally hot S1 (1(1)Ag-) state and with the exception of violaxanthin also to the S* state. The vibrationally hot S1 (1(1)Ag-) state then cools to a vibrationally relaxed S1 (2(1)Ag-) state in less than a picosecond. It was also found that a portion

  7. Exploratory study on a statistical method to analyse time resolved data obtained during nanomaterial exposure measurements

    NASA Astrophysics Data System (ADS)

    Clerc, F.; Njiki-Menga, G.-H.; Witschger, O.

    2013-04-01

    Most of the measurement strategies that are suggested at the international level to assess workplace exposure to nanomaterials rely on devices measuring, in real time, airborne particles concentrations (according different metrics). Since none of the instruments to measure aerosols can distinguish a particle of interest to the background aerosol, the statistical analysis of time resolved data requires special attention. So far, very few approaches have been used for statistical analysis in the literature. This ranges from simple qualitative analysis of graphs to the implementation of more complex statistical models. To date, there is still no consensus on a particular approach and the current period is always looking for an appropriate and robust method. In this context, this exploratory study investigates a statistical method to analyse time resolved data based on a Bayesian probabilistic approach. To investigate and illustrate the use of the this statistical method, particle number concentration data from a workplace study that investigated the potential for exposure via inhalation from cleanout operations by sandpapering of a reactor producing nanocomposite thin films have been used. In this workplace study, the background issue has been addressed through the near-field and far-field approaches and several size integrated and time resolved devices have been used. The analysis of the results presented here focuses only on data obtained with two handheld condensation particle counters. While one was measuring at the source of the released particles, the other one was measuring in parallel far-field. The Bayesian probabilistic approach allows a probabilistic modelling of data series, and the observed task is modelled in the form of probability distributions. The probability distributions issuing from time resolved data obtained at the source can be compared with the probability distributions issuing from the time resolved data obtained far-field, leading in a

  8. Time resolved optical tomography of the human forearm

    NASA Astrophysics Data System (ADS)

    Hillman, Elizabeth M. C.; Hebden, Jeremy C.; Schweiger, Martin; Dehghani, Hamid; Schmidt, Florian E. W.; Delpy, David T.; Arridge, Simon R.

    2001-04-01

    A 32-channel time-resolved optical imaging instrument has been developed principally to study functional parameters of the new-born infant brain. As a prelude to studies on infants, the device and image reconstruction methodology have been evaluated on the adult human forearm. Cross-sectional images were generated using time-resolved measurements of transmitted light at two wavelengths. All data were acquired using a fully automated computer-controlled protocol. Images representing the internal scattering and absorbing properties of the arm are presented, as well as images that reveal physiological changes during a simple finger flexion exercise. The results presented in this paper represent the first simultaneous tomographic reconstruction of the internal scattering and absorbing properties of a clinical subject using purely temporal data, with additional co-registered difference images showing repeatable absorption changes at two wavelengths in response to exercise.

  9. Time resolved optical tomography of the human forearm.

    PubMed

    Hillman, E M; Hebden, J C; Schweiger, M; Dehghani, H; Schmidt, F E; Delpy, D T; Arridge, S R

    2001-04-01

    A 32-channel time-resolved optical imaging instrument has been developed principally to study functional parameters of the new-born infant brain. As a prelude to studies on infants, the device and image reconstruction methodology have been evaluated on the adult human forearm. Cross-sectional images were generated using time-resolved measurements of transmitted light at two wavelengths. All data were acquired using a fully automated computer-controlled protocol. Images representing the internal scattering and absorbing properties of the arm are presented, as well as images that reveal physiological changes during a simple finger flexion exercise. The results presented in this paper represent the first simultaneous tomographic reconstruction of the internal scattering and absorbing properties of a clinical subject using purely temporal data, with additional co-registered difference images showing repeatable absorption changes at two wavelengths in response to exercise.

  10. Time-Resolved Rayleigh Scattering Measurements in Hot Gas Flows

    NASA Technical Reports Server (NTRS)

    Mielke, Amy F.; Elam, Kristie A.; Sung, Chih-Jen

    2008-01-01

    A molecular Rayleigh scattering technique is developed to measure time-resolved gas velocity, temperature, and density in unseeded gas flows at sampling rates up to 32 kHz. A high power continuous-wave laser beam is focused at a point in an air flow field and Rayleigh scattered light is collected and fiber-optically transmitted to the spectral analysis and detection equipment. The spectrum of the light, which contains information about the temperature and velocity of the flow, is analyzed using a Fabry-Perot interferometer. Photomultipler tubes operated in the photon counting mode allow high frequency sampling of the circular interference pattern to provide time-resolved flow property measurements. Mean and rms velocity and temperature fluctuation measurements in both an electrically-heated jet facility with a 10-mm diameter nozzle and also in a hydrogen-combustor heated jet facility with a 50.8-mm diameter nozzle at NASA Glenn Research Center are presented.

  11. Time resolved Schlieren imaging of DBD actuator flow fields

    NASA Astrophysics Data System (ADS)

    Nourgostar, Cyrus; Oksuz, Lutfi; Hershkowitz, Noah

    2009-10-01

    Schlieren imaging methods measure the first derivative of density in the direction of a knife-edge spatial filter. It has been used extensively in aerodynamic research to visualize the structure of flow fields. With a single barrier planer dielectric barrier discharge (DBD) actuator, Schlieren images clearly show the absence of significant vertical air flow normal to the surface, and no more than few millimeters thick induced boundary layer flow. A gated intensified CCD camera along with a Schlieren system can not only visualize the flow field induced by the actuator, but also temporarily resolve the images of the flow and plasma field. Our time resolved images with triangular applied voltage waveforms indicate that several separate discharge regimes occur during positive and negative going half cycles of single and double barrier DBD actuators. Time resolved Schlieren imaging of both single and double barrier DBDs with different applied waveforms, discharge parameters and electrode geometries reveal important information on the induced flow structure.

  12. Benchtop time-resolved magneto-optical Kerr magnetometer.

    PubMed

    Barman, Anjan; Kimura, T; Otani, Y; Fukuma, Y; Akahane, K; Meguro, S

    2008-12-01

    We present here the construction and application of a compact benchtop time-resolved Kerr magnetometer to measure the magnetization precession in magnetic thin films and lithographically patterned elements. As opposed to very expensive femtosecond lasers this system is built upon a picosecond pulsed injection diode laser and electronic pulse and delay generators. The precession is triggered by the electronic pulses of controlled duration and shape, which is launched onto the sample by a microstrip line. We used polarized optical pulses synchronous to the electronic pulses to measure the magneto-optical Kerr rotation. The system is integrated in a conventional upright microscope configuration with separate illumination, imaging, and magneto-optical probe paths. The system offers high stability, relative ease of alignment, sample changing, and a long range of time delay. We demonstrate the measurements of time-resolved dynamics of a Permalloy microwire and microdot using this system, which showed dynamics at two different time scales.

  13. Time-resolved single dopant charge dynamics in silicon

    NASA Astrophysics Data System (ADS)

    Rashidi, Mohammad; Burgess, Jacob A. J.; Taucer, Marco; Achal, Roshan; Pitters, Jason L.; Loth, Sebastian; Wolkow, Robert A.

    2016-10-01

    As the ultimate miniaturization of semiconductor devices approaches, it is imperative that the effects of single dopants be clarified. Beyond providing insight into functions and limitations of conventional devices, such information enables identification of new device concepts. Investigating single dopants requires sub-nanometre spatial resolution, making scanning tunnelling microscopy an ideal tool. However, dopant dynamics involve processes occurring at nanosecond timescales, posing a significant challenge to experiment. Here we use time-resolved scanning tunnelling microscopy and spectroscopy to probe and study transport through a dangling bond on silicon before the system relaxes or adjusts to accommodate an applied electric field. Atomically resolved, electronic pump-probe scanning tunnelling microscopy permits unprecedented, quantitative measurement of time-resolved single dopant ionization dynamics. Tunnelling through the surface dangling bond makes measurement of a signal that would otherwise be too weak to detect feasible. Distinct ionization and neutralization rates of a single dopant are measured and the physical process controlling those are identified.

  14. Knee rotation influences the femoral tunnel angle measurement after anterior cruciate ligament reconstruction: a 3-dimensional computed tomography model study.

    PubMed

    Tang, Jing; Thorhauer, Eric; Marsh, Chelsea; Fu, Freddie H; Tashman, Scott

    2014-07-01

    Femoral tunnel angle (FTA) has been proposed as a metric for evaluating whether ACL reconstruction was performed anatomically. In clinic, radiographic images are typically acquired with an uncertain amount of internal/external knee rotation. The extent to which knee rotation will influence FTA measurement is unclear. Furthermore, differences in FTA measurement between the two common positions (0° and 45° knee flexion) have not been established. The purpose of this study was to investigate the influence of knee rotation on FTA measurement after ACL reconstruction. Knee CT data from 16 subjects were segmented to produce 3D bone models. Central axes of tunnels were identified. The 0° and 45° flexion angles were simulated. Knee internal/external rotations were simulated in a range of ± 20°. FTA was defined as the angle between the tunnel axis and femoral shaft axis, orthogonally projected into the coronal plane. Femoral tunnel angle was positively/negatively correlated with knee rotation angle at 0°/45° knee flexion. At 0° knee flexion, FTA for anterio-medial (AM) tunnels was significantly decreased at 20° of external knee rotation. At 45° knee flexion, more than 16° external or 19° internal rotation significantly altered FTA measurements for single-bundle tunnels; smaller rotations (± 9° for AM, ± 5° for PL) created significant errors in FTA measurements after double-bundle reconstruction. Femoral tunnel angle measurements were correlated with knee rotation. Relatively small imaging malalignment introduced significant errors with knee flexed 45°. This study supports using the 0° flexion position for knee radiographs to reduce errors in FTA measurement due to knee internal/external rotation.

  15. Time resolved optical spectra from MIG welding arc ignitions

    SciTech Connect

    Eriksen, P.

    1985-03-01

    Optical radiation from MIG (GMAW) welding arc ignitions has been measured with a rapid scan spectrometer. The time resolved spectral measurements reveal a substantial overshoot of ultraviolet radiation during the ignition phase of a 200 A aluminum arc. Calculations which follow the ACGIH guidelines show that, at a welding current of 300 A, the unprotected eye at a distance of 0.5 m may suffer a flash after the reception of radiation from only one ignition.

  16. The RATIO method for time-resolved Laue crystallography

    PubMed Central

    Coppens, Philip; Pitak, Mateusz; Gembicky, Milan; Messerschmidt, Marc; Scheins, Stephan; Benedict, Jason; Adachi, Shin-ichi; Sato, Tokushi; Nozawa, Shunsuke; Ichiyanagi, Kohei; Chollet, Matthieu; Koshihara, Shin-ya

    2009-01-01

    A RATIO method for analysis of intensity changes in time-resolved pump–probe Laue diffraction experiments is described. The method eliminates the need for scaling the data with a wavelength curve representing the spectral distribution of the source and removes the effect of possible anisotropic absorption. It does not require relative scaling of series of frames and removes errors due to all but very short term fluctuations in the synchrotron beam. PMID:19240334

  17. Ultrafast Time-Resolved Electron Diffraction with Megavolt Electron Beams

    SciTech Connect

    Hastings, J.B.; Rudakov, F.M.; Dowell, D.H.; Schmerge, J.F.; Cardoza, J.D.; Castro, J.M.; Gierman, S.M.; Loos, H.; Weber, P.M.; /Brown U.

    2006-10-24

    An rf photocathode electron gun is used as an electron source for ultrafast time-resolved pump-probe electron diffraction. We observed single-shot diffraction patterns from a 160 nm Al foil using the 5.4 MeV electron beam from the Gun Test Facility at the Stanford Linear Accelerator. Excellent agreement with simulations suggests that single-shot diffraction experiments with a time resolution approaching 100 fs are possible.

  18. Time-resolved Raman spectroscopy for in situ planetary mineralogy.

    PubMed

    Blacksberg, Jordana; Rossman, George R; Gleckler, Anthony

    2010-09-10

    Planetary mineralogy can be revealed through a variety of remote sensing and in situ investigations that precede any plans for eventual sample return. We briefly review those techniques and focus on the capabilities for on-surface in situ examination of Mars, Venus, the Moon, asteroids, and other bodies. Over the past decade, Raman spectroscopy has continued to develop as a prime candidate for the next generation of in situ planetary instruments, as it provides definitive structural and compositional information of minerals in their natural geological context. Traditional continuous-wave Raman spectroscopy using a green laser suffers from fluorescence interference, which can be large (sometimes saturating the detector), particularly in altered minerals, which are of the greatest geophysical interest. Taking advantage of the fact that fluorescence occurs at a later time than the instantaneous Raman signal, we have developed a time-resolved Raman spectrometer that uses a streak camera and pulsed miniature microchip laser to provide picosecond time resolution. Our ability to observe the complete time evolution of Raman and fluorescence spectra in minerals makes this technique ideal for exploration of diverse planetary environments, some of which are expected to contain strong, if not overwhelming, fluorescence signatures. We discuss performance capability and present time-resolved pulsed Raman spectra collected from several highly fluorescent and Mars-relevant minerals. In particular, we have found that conventional Raman spectra from fine grained clays, sulfates, and phosphates exhibited large fluorescent signatures, but high quality spectra could be obtained using our time-resolved approach.

  19. Detection of colorectal cancer using time-resolved autofluorescence spectrometer

    NASA Astrophysics Data System (ADS)

    Fu, Sheng; Kwek, Leong-Chuan; Chia, Teck-Chee; Lim, Chu-Sing; Tang, Choong-Leong; Ang, Wuan-Suan; Zhou, Miao-Chang; Loke, Po-Ling

    2006-04-01

    As we know Quantum mechanics is a mathematical theory that can describe the behavior of objects that are at microscopic level. Time-resolved autofluorescence spectrometer monitors events that occur during the lifetime of the excited state. This time ranges from a few picoseconds to hundreds of nanoseconds. That is an extremely important advance as it allows environmental parameters to be monitored in a spatially defined manner in the specimen under study. This technique is based on the application of Quantum Mechanics. This principle is applied in our project as we are trying to use different fluorescence spectra to detect biological molecules commonly found in cancerous colorectal tissue and thereby differentiate the cancerous and non-cancerous colorectal polyps more accurately and specifically. In this paper, we use Fluorescence Lifetime Spectrometer (Edinburgh Instruments FL920) to measure decay time of autofluorescence of colorectal cancerous and normal tissue sample. All specimens are from Department of Colorectal Surgery, Singapore General Hospital. The tissues are placed in the time-resolved autofluorescence instrument, which records and calculates the decay time of the autofluorescence in the tissue sample at the excitation and emission wavelengths pre-determined from a conventional spectrometer. By studying the decay time,τ, etc. for cancerous and normal tissue, we aim to present time-resolved autofluorescence as a feasible technique for earlier detection of malignant colorectal tissues. By using this concept, we try to contribute an algorithm even an application tool for real time early diagnosis of colorectal cancer for clinical services.

  20. Time-resolved spectroscopy of the pulsating CV GW Lib

    NASA Astrophysics Data System (ADS)

    van Spaandonk, L.; Steeghs, D.; Marsh, T. R.; Torres, M. A. P.

    2010-01-01

    We present time-resolved optical spectroscopy of the dwarf nova GW Librae during its rare 2007 April superoutburst and compare these with quiescent epochs. The data provide the first opportunity to track the evolution of the principal spectral features. In the early stages of the outburst, the optically thick disc dominates the optical and the line components show clear orbital radial velocity excursions. In the course of several weeks, optically thin regions become more prominent as strong emission lines replace the broad disc absorption. Post-outburst spectroscopy covering the I band illustrates the advantages of CaII relative to the commonly used Balmer lines when attempting to constrain binary parameters. Due to the lower ionization energy combined with smaller thermal and shear broadening of these lines, a sharp emission component is seen to be moving in between the accretion disc peaks in the CaII line. No such component is visible in the Balmer lines. We interpret this as an emission component originating on the hitherto unseen mass donor star. This emission component has a mean velocity of ~ -15 +/- 5 kms-1 which is associated with the systemic velocity γ, and a velocity semi-amplitude of Kem = 82.2 +/- 4.9 kms-1. Doppler tomography reveals an asymmetric accretion disc, with the S-wave mapping to a sharp spot in the tomogram with a velocity consistent to what is obtained with line profile fitting. A centre of symmetry analysis of the disc component suggests a very small value for the WD orbital velocity K1 as is also inferred from double Gaussian fits to the spectral lines. While our conservative dynamical limits place a hard upper limit on the binary mass ratio of q < 0.23, we favour a significantly lower value near q ~ 0.06. Pulsation modelling suggests a white dwarf mass ~1Msolar. This, paired with a low-mass donor, near the empirical sequence of an evolved cataclysmic variable close to the period bounce, appears to be consistent with all the

  1. Lucas-Kanade fluid trajectories for time-resolved PIV

    NASA Astrophysics Data System (ADS)

    Yegavian, Robin; Leclaire, Benjamin; Champagnat, Frédéric; Illoul, Cédric; Losfeld, Gilles

    2016-08-01

    We introduce a new method for estimating fluid trajectories in time-resolved PIV. It relies on a Lucas-Kanade paradigm and consists in a simple and direct extension of a two-frame estimation with FOLKI-PIV (Champagnat et al 2011 Exp. Fluids 50 1169-82). The so-called Lucas-Kanade Fluid Trajectories (LKFT) are assumed to be polynomial in time, and are found as the minimizer of a global functional, in which displacements are sought so as to match the intensities of a series of images pairs in the sequence, in the least-squares sense. All pairs involve the central image, similar to other recent time-resolved approaches (FTC (Lynch and Scarano 2013 Meas. Sci. Technol. 24 035305) and FTEE (Jeon et al 2014 Exp. Fluids 55 1-16)). As switching from a two-frame to a time-resolved objective simply amounts to adding terms in a functional, no significant additional algorithmic element is required. Similar to FOLKI-PIV the method is very well suited for GPU acceleration, which is an important feature as computational complexity increases with the image sequence size. Tests on synthetic data exhibiting peak-locking show that increasing the image sequence size strongly reduces both associated bias and random error, and that LKFT has a remaining total error comparable to that of FTEE on this case. Results on case B of the third PIV challenge (Stanislas et al 2008 Exp. Fluids 45 27-71) also show its ability to drastically reduce the error in situations with low signal-to-noise ratio. These results are finally confirmed on experimental images acquired in the near-field of a low Reynolds number jet. Strong reductions in peak-locking, spatial and temporal noise compared to two-frame estimation are also observed, on the displacement components themselves, as well as on spatial or temporal derivatives, such as vorticity and material acceleration.

  2. Time-resolved resonance Raman spectroscopy: exploring reactive intermediates.

    PubMed

    Sahoo, Sangram Keshari; Umapathy, Siva; Parker, Anthony W

    2011-10-01

    The study of reaction mechanisms involves systematic investigations of the correlation between structure, reactivity, and time. The challenge is to be able to observe the chemical changes undergone by reactants as they change into products via one or several intermediates such as electronic excited states (singlet and triplet), radicals, radical ions, carbocations, carbanions, carbenes, nitrenes, nitrinium ions, etc. The vast array of intermediates and timescales means there is no single "do-it-all" technique. The simultaneous advances in contemporary time-resolved Raman spectroscopic techniques and computational methods have done much towards visualizing molecular fingerprint snapshots of the reactive intermediates in the microsecond to femtosecond time domain. Raman spectroscopy and its sensitive counterpart resonance Raman spectroscopy have been well proven as means for determining molecular structure, chemical bonding, reactivity, and dynamics of short-lived intermediates in solution phase and are advantageous in comparison to commonly used time-resolved absorption and emission spectroscopy. Today time-resolved Raman spectroscopy is a mature technique; its development owes much to the advent of pulsed tunable lasers, highly efficient spectrometers, and high speed, highly sensitive multichannel detectors able to collect a complete spectrum. This review article will provide a brief chronological development of the experimental setup and demonstrate how experimentalists have conquered numerous challenges to obtain background-free (removing fluorescence), intense, and highly spectrally resolved Raman spectra in the nanosecond to microsecond (ns-μs) and picosecond (ps) time domains and, perhaps surprisingly, laid the foundations for new techniques such as spatially offset Raman spectroscopy. © 2011 Society for Applied Spectroscopy

  3. Time-Resolved Conformational Dynamics in Hydrocarbon Chains

    SciTech Connect

    Minitti, Michael P.; Weber, Peter M.

    2007-06-22

    Internal rotation about carbon-carbon bonds allows N,N-dimethyl-2-butanamine (DM2BA) and N,N-dimethyl-3-hexanamine (DM3HA) to assume multiple conformeric structures. We explore the equilibrium composition and dynamics between such conformeric structures using Rydberg fingerprint spectroscopy. Time constants for conformeric interconversion of DM2BA (at 1.79 eV of internal energy) are 19 and 66 ps, and for DM3HA (1.78 eV) 23 and 41 ps. For the first time, a time-resolved and quantitative view of conformational dynamics of flexible hydrocarbon molecules at high temperatures is revealed.

  4. Time-resolved fluorescence decay measurements for flowing particles

    DOEpatents

    Deka, C.; Steinkamp, J.A.

    1999-06-01

    Time-resolved fluorescence decay measurements are disclosed for flowing particles. An apparatus and method for the measurement and analysis of fluorescence for individual cells and particles in flow are described, wherein the rapid measurement capabilities of flow cytometry and the robust measurement and analysis procedures of time-domain fluorescence lifetime spectroscopy are combined. A pulse-modulated CW laser is employed for excitation of the particles. The characteristics and the repetition rate of the excitation pulses can be readily adjusted to accommodate for fluorescence decays having a wide range of lifetimes. 12 figs.

  5. Time-resolved fluorescence decay measurements for flowing particles

    DOEpatents

    Deka, Chiranjit; Steinkamp, John A.

    1999-01-01

    Time-resolved fluorescence decay measurements for flowing particles. An apparatus and method for the measurement and analysis of fluorescence for individual cells and particles in flow are described, wherein the rapid measurement capabilities of flow cytometry and the robust measurement and analysis procedures of time-domain fluorescence lifetime spectroscopy are combined. A pulse-modulated cw laser is employed for excitation of the particles. The characteristics and the repetition rate of the excitation pulses can be readily adjusted to accommodate for fluorescence decays having a wide range of lifetimes.

  6. Time Resolved Raman and Fluorescence Spectrometer for Planetary Mineralogy

    NASA Astrophysics Data System (ADS)

    Blacksberg, Jordana; Rossman, George

    2010-05-01

    Raman spectroscopy is a prime candidate for the next generation of planetary instruments, as it addresses the primary goal of mineralogical analysis which is structure and composition. It does not require sample preparation and provides unique mineral fingerprints, even for mixed phase samples. However, large fluorescence return from many mineral samples under visible light excitation can seriously compromise the quality of the spectra or even render Raman spectra unattainable. Fluorescence interference is likely to be a problem on Mars and is evident in Raman spectra of Martian Meteorites[1]. Our approach uses time resolution for elimination of fluorescence from Raman spectra, allowing for traditional visible laser excitation (532 nm). Since Raman occurs instantaneously with the laser pulse and fluorescence lifetimes vary from nsec to msec depending on the mineral, it is possible to separate them out in time. Complementary information can also be obtained simultaneously using the time resolved fluorescence data. The Simultaneous Spectral Temporal Adaptive Raman Spectrometer (SSTARS) is a planetary instrument under development at the Jet Propulsion Laboratory, capable of time-resolved in situ Raman and fluorescence spectroscopy. A streak camera and pulsed miniature microchip laser provide psec scale time resolution. Our ability to observe the complete time evolution of Raman and fluorescence in minerals provides a foundation for design of pulsed Raman and fluorescence spectrometers in diverse planetary environments. We will discuss the SSTARS instrument design and performance capability. We will also present time-resolved pulsed Raman spectra collected from a relevant set of minerals selected using available data on Mars mineralogy[2]. Of particular interest are minerals resulting from aqueous alteration on Mars. For comparison, we will present Raman spectra obtained using a commercial continuous wave (CW) green (514 nm) Raman system. In many cases using a CW laser

  7. Time-resolved SERS for characterizing extracellular vesicles

    NASA Astrophysics Data System (ADS)

    Rojalin, Tatu; Saari, Heikki; Somersalo, Petter; Laitinen, Saara; Turunen, Mikko; Viitala, Tapani; Wachsmann-Hogiu, Sebastian; Smith, Zachary J.; Yliperttula, Marjo

    2017-02-01

    The aim of this work is to develop a platform for characterizing extracellular vesicles (EV) by using gold-polymer nanopillar SERS arrays simultaneously circumventing the photoluminescence-related disadvantages of Raman with a time-resolved approach. EVs are rich of biochemical information reporting of, for example, diseased state of the biological system. Currently, straightforward, label-free and fast EV characterization methods with low sample consumption are warranted. In this study, SERS spectra of red blood cell and platelet derived EVs were successfully measured and their biochemical contents analyzed using multivariate data analysis techniques. The developed platform could be conveniently used for EV analytics in general.

  8. A compact electron gun for time-resolved electron diffraction

    SciTech Connect

    Robinson, Matthew S.; Lane, Paul D.; Wann, Derek A.

    2015-01-15

    A novel compact time-resolved electron diffractometer has been built with the primary goal of studying the ultrafast molecular dynamics of photoexcited gas-phase molecules. Here, we discuss the design of the electron gun, which is triggered by a Ti:Sapphire laser, before detailing a series of calibration experiments relating to the electron-beam properties. As a further test of the apparatus, initial diffraction patterns have been collected for thin, polycrystalline platinum samples, which have been shown to match theoretical patterns. The data collected demonstrate the focusing effects of the magnetic lens on the electron beam, and how this relates to the spatial resolution of the diffraction pattern.

  9. Time resolved structural dynamics of butadiyne-linked porphyrin dimers

    PubMed Central

    Camargo, Franco V. A.; Hall, Christopher R.; Anderson, Harry L.; Meech, Stephen R.; Heisler, Ismael A.

    2016-01-01

    In this work, the timescales and mechanisms associated with the structural dynamics of butadiyne-linked porphyrin dimers are investigated through time resolved narrowband pump/broadband probe transient absorption spectroscopy. Our results confirm previous findings that the broadening is partly due to a distribution of structures with different (dihedral) angular conformations. Comparison of measurements with excitations on the red and blue sides of the Q-band unravel the ground and excited state conformational re-equilibration timescales. Further comparison to a planarized dimer, through the addition of a ligand, provides conclusive evidence for the twisting motion performed by the porphyrin dimer in solution. PMID:26798839

  10. Sensitive, time-resolved, broadband spectroscopy of single transient processes

    NASA Astrophysics Data System (ADS)

    Fjodorow, Peter; Baev, Ivan; Hellmig, Ortwin; Sengstock, Klaus; Baev, Valery M.

    2015-09-01

    Intracavity absorption spectroscopy with a broadband Er3+-doped fiber laser is applied to time-resolved measurements of transient gain and absorption in electrically excited Xe and Kr plasmas. The achieved time resolution for broadband spectral recording of a single process is 25 µs. For pulsed-periodic processes, the time resolution is limited by the laser pulse duration, which is set here to 3 µs. This pulse duration also predefines the effective absorption path length, which amounts to 900 m. The presented technique can be applied to multicomponent analysis of single transient processes such as shock tube experiments, pulse detonation engines, or explosives.

  11. Femtosecond time-resolved electronic relaxation dynamics in tetrathiafulvalene

    SciTech Connect

    Staedter, D.; Polizzi, L.; Thiré, N.; Mairesse, Y.; Mayer, P.; Blanchet, V.

    2015-05-21

    In the present paper, the ultrafast electronic relaxation of tetrathiafulvalene (TTF) initiated around 4 eV is studied by femtosecond time-resolved velocity-map imaging. The goal is to investigate the broad double structure observed in the absorption spectrum at this energy. By monitoring the transients of the parent cation and its fragments and by varying the pump and the probe wavelengths, two internal conversions and intramolecular vibrational relaxation are detected both on the order of a few hundred of femtoseconds. Photoelectron images permit the assignment of a dark electronic state involved in the relaxation. In addition, the formation of the dimer of TTF has been observed.

  12. Coherent state statistics from time-resolved photon counting

    NASA Astrophysics Data System (ADS)

    Ravi, Harish; Prabhakar, Anil

    2011-01-01

    Time resolved photon counting was used to separate the different photon states emitted from a strongly attenuated laser source. We first describe a method to quantify the efficiency of our gated avalanche photo-detector, by relying on known Poissonian statistics. The detector was then optimized under different temperature and bias voltage conditions using the noise equivalent power as a metric. Finally, coherent pulses are sent into a ring cavity, such that the tapped output from the cavity forms a series of time multiplexed pulses, which then yield the photon counting statistics. We observed good agreement between theoretical estimates and experimental observations, to as low as 0.01% probability of detection.

  13. Coupling between the bacteriorhodopsin photocycle and the protonmotive force in Halobacterium halobium cell envelope vesicles. III. Time-resolved increase in the transmembrane electric potential and modeling of the associated ion fluxes.

    PubMed Central

    Helgerson, S L; Mathew, M K; Bivin, D B; Wolber, P K; Heinz, E; Stoeckenius, W

    1985-01-01

    Bacteriorhodopsin functions as an electrogenic, light-driven proton pump in Halobacterium halobium. In cell envelope vesicles, its photocycle kinetics can be correlated with membrane potential. The initial decay rate of the M photocycle intermediate(s) decreases with increasing membrane potential, allowing the construction of a calibration curve. The laser (592.5 nm) was flashed at various time delays following the start of background illumination (592 +/- 25 nm) and transient absorbance changes at 418 nm monitored in cell envelope vesicles. The vesicles were loaded with and suspended in either 3 M NaCl or 3 M KCl buffered with 50 mM HEPES at pH 7.5 and the membrane permeability to protons modified by pretreatment with N,N'-dicyclohexylcarbodiimide. In each case the membrane potential rose with a halftime of approximately 75 ms. The steady-state potential achieved depends on the cation present and the proton permeability of the membrane, i.e., higher potentials are developed in dicyclohexylcarbodiimide treated vesicles or in NaCl media as compared with KCl media. The results are modeled using an irreversible thermodynamics formulation, which assumes a constant driving reaction affinity (Ach) and a variable reaction rate (Jr) for the proton-pumping cycle of bacteriorhodopsin. Additionally, the model includes a voltage-gated, electrogenic Na+/H+ antiporter that is active when vesicles are suspended in NaCl. Estimates for the linear phenomenological coefficients describing the overall proton-pumping cycle (Lr = 3.5 X 10(-11)/mol2/J X g X s), passive cation permeabilities (LHu = 2 X 10(-10), LKu = 2.2 X 10(-10), LNau = 1 X 10(-11)), and the Na+/H+ exchange via the antiporter (Lex = 5 X 10(-11)) have been obtained. PMID:4074833

  14. Experimental Time Resolved Electron Beam Temperature Measurements Using Bremsstrahlung Diagnostics

    SciTech Connect

    Menge, P.R.; Maenchen, J.E.; Mazarakis, M.G.; Rosenthal, S.E.

    1999-06-25

    Electron beam temperature, {beta}{perpendicular} (= v{perpendicular}/v), is important to control for the development of high dose flash radiographic bremsstrahlung sources. At high voltage (> 5 MV) increasing electron beam temperature has a serious deleterious effect on dose production. The average and time resolved behavior of beam temperature was measured during radiographic experiments on the HERMES III accelerator (10 MV, 50 kA, 70 ns). A linear array of thermoluminescent dosimeters (TLDs) were used to estimate the time integrated average of beam temperature. On and off-axis photoconducting diamond (PCD) detectors were used to measure the time resolved bremsstrahlung dose rate, which is dependent on beam energy and temperature. The beam temperature can be determined by correlating PCD response with accelerator voltage and current and also by analyzing the ratio of PCD amplitudes on and off axis. This ratio is insensitive to voltage and current and thus, is more reliable than utilizing absolute dose rate. The data is unfolded using comparisons with Monte Carlo simulations to obtain absolute beam temperatures. The data taken on HERMES III show abrupt increases in {beta}{perpendicular} midway through the pulse indicating rapid onset of beam instability.

  15. Portable optical oxygen sensor based on time-resolved fluorescence.

    PubMed

    Chu, Cheng-Shane; Chu, Ssu-Wei

    2014-11-10

    A new, simple signal processing, low-cost technique for the fabrication of a portable oxygen sensor based on time-resolved fluorescence is described. The sensing film uses the oxygen sensing dye platinum meso-tetra (pentfluorophenyl) porphyrin (PtTFPP) embedded in a polymer matrix. The ratio τ0100 measures sensitivity of the sensing film, where τ0 and τ100 represent the detected fluorescence lifetimes from the sensing film exposed to 100% nitrogen and 100% oxygen, respectively. The experimental results reveal that the PtTFPP-doped oxygen sensor has a sensitivity of 2.2 in the 0%-100% range. A preparation procedure for coating the photodiodes with the oxygen sensor film that produces repetitive and reliable sensing devices is proposed. The developed time-resolved optical oxygen sensor is portable, low-cost, has simple signal processing, and lacks optical filter elements. It is a cost-effective alternative to traditional electrochemical-based oxygen sensors and provides a platform for other optical based sensors.

  16. Time-resolved videothermography at above-frame-rate frequencies

    NASA Astrophysics Data System (ADS)

    Shepard, Steven M.; Sass, David T.; Imirowicz, Thomas P.; Meng, A.

    1991-03-01

    Temporal aliasing is a problem common all video imaging systems. IR video systems are particularly susceptible because of the relatively low (30 Hz) RS-170 frame rate. We have developed a system which compensates for the effects of aliasing, and allows images of repetitive thermal phenomena at frequencies up to 4 kHz to be acquired. The system utilizes an unmodified commercial imager (Inframetrics IR 600) and a microcomputer. Data is acquired selectively using a 'line-by-line' scheme which compares the motion of the camera's horizontal scanning mirror to a reference signal correlated to the event of interest. Only those horizontal lines that have a user-specified phase relationship to the reference signal are acquired. The resulting images have an effective integration time of 125 microseconds. This ability to acquire 'time-resolved' IR images allows investigation of phenomena not possible with a conventional RS-170 IR imaging system. For example, a conventional thermal image of an integrated circuit operating at several kilohertz yields no temporal information whatsoever. By comparison, we have acquired time-resolved images which show the AC heating and cooling of the circuit, so that we may identify AC hot spots. The system has also been applied to a running internal combustion engine. The imager views the piston head through an IR transparent (ZnS) window. Acquired images clearly show the motion of the flame front through the combustion chamber, and the subsequent heating and cooling of the piston head.

  17. Time-resolved fluorescence study of all-trans-retinal

    NASA Astrophysics Data System (ADS)

    Erez, Yuval; Presiado, Itay; Gepshtein, Rinat; Simkovitch, Ron; Huppert, Dan

    2014-11-01

    UV-vis steady-state and time-resolved emission techniques were employed to study the ultrafast relaxation path of all-trans-retinal. We found that the steady-state emission spectrum consists mainly of two bands that we assign to the allowed transition from the ? state and the forbidden transition from the ?(ππ*) state. The time-resolved emission signal is dependent on the excitation wavelength, and is composed of three decay components. The short-time component of less than 80 fs, irrespective of the solvent, is assigned to the transition from the ? state. The intermediate-time decay component is assigned to the transition from the ?(ππ*) state, depends on the solvent's polarity and not on the existence of hydrogen bonds between the solute and the solvent or the viscosity of the latter. It has a lifetime of ~1 ps in polar solvents, and of 0.6 and 0.4 ps in the non-polar solvents n-octane and cyclohexane, respectively.

  18. Time-resolved luminescent lateral flow assay technology.

    PubMed

    Song, Xuedong; Knotts, Michael

    2008-09-26

    We here report a detection technology that integrates highly sensitive time-resolved luminescence technique into lateral flow assay platform to achieve excellent detection performance with low cost. We have developed very bright, surface-functionalized and mono-dispersed phosphorescent nanoparticles of long lifetime under ambient conditions. The phosphorescent nanoparticles have been used to conjugate with monoclonal antibody for C-reactive protein (CRP), an inflammatory biomarker. Lateral flow immunoassay devices have been developed using the conjugate for highly sensitive detection of CRP. The CRP assay can achieve a detection sensitivity of <0.2 ngmL(-1) in serum with a linear response from 0.2 to 200 ngmL(-1) CRP. We have also developed a low cost time-resolved luminescence reader for the lateral flow immunoassay (LFIA) devices. The reader does not use expensive band pass filter and still provide very low detection background and high detection sensitivity on solid substrates such as nitrocellulose membranes. The reader can detect less than 2.5 ng phosphorescent particles captured on a nitrocellulose membrane strip with more than three orders of magnitude linear detection dynamic range. The technology should find a number of applications, ranging from clinical diagnostics, detection of chemical and biological warfare agents, to food and environmental monitoring.

  19. Time Resolved FTIR Analysis of Tailpipe Exhaust for Several Automobiles

    NASA Astrophysics Data System (ADS)

    White, Allen R.; Allen, James; Devasher, Rebecca B.

    2011-06-01

    The automotive catalytic converter reduces or eliminates the emission of various chemical species (e.g. CO, hydrocarbons, etc.) that are the products of combustion from automobile exhaust. However, these units are only effective once they have reached operating temperature. The design and placement of catalytic converters has changed in order to reduce both the quantity of emissions and the time that is required for the converter to be effective. In order to compare the effectiveness of catalytic converters, time-resolved measurements were performed on several vehicles, including a 2010 Toyota Prius, a 2010 Honda Fit, a 1994 Honda Civic, and a 1967 Oldsmobile 442 (which is not equipped with a catalytic converter but is used as a baseline). The newer vehicles demonstrate bot a reduced overall level of CO and hydrocarbon emissions but are also effective more quickly than older units. The time-resolved emissions will be discussed along with the impact of catalytic converter design and location on the measured emissions.

  20. Structural kinetics of myosin by transient time-resolved FRET

    PubMed Central

    Nesmelov, Yuri E.; Agafonov, Roman V.; Negrashov, Igor V.; Blakely, Sarah E.; Titus, Margaret A.; Thomas, David D.

    2011-01-01

    For many proteins, especially for molecular motors and other enzymes, the functional mechanisms remain unsolved due to a gap between static structural data and kinetics. We have filled this gap by detecting structure and kinetics simultaneously. This structural kinetics experiment is made possible by a new technique, (TR)2FRET (transient time-resolved FRET), which resolves protein structural states on the submillisecond timescale during the transient phase of a biochemical reaction. (TR)2FRET is accomplished with a fluorescence instrument that uses a pulsed laser and direct waveform recording to acquire an accurate subnanosecond time-resolved fluorescence decay every 0.1 ms after stopped flow. To apply this method to myosin, we labeled the force-generating region site specifically with two probes, mixed rapidly with ATP to initiate the recovery stroke, and measured the interprobe distance by (TR)2FRET with high resolution in both space and time. We found that the relay helix bends during the recovery stroke, most of which occurs before ATP is hydrolyzed, and two structural states (relay helix straight and bent) are resolved in each nucleotide-bound biochemical state. Thus the structural transition of the force-generating region of myosin is only loosely coupled to the ATPase reaction, with conformational selection driving the motor mechanism. PMID:21245357

  1. Time resolved fluorescence of cow and goat milk powder

    NASA Astrophysics Data System (ADS)

    Brandao, Mariana P.; de Carvalho dos Anjos, Virgílio; Bell., Maria José V.

    2017-01-01

    Milk powder is an international dairy commodity. Goat and cow milk powders are significant sources of nutrients and the investigation of the authenticity and classification of milk powder is particularly important. The use of time-resolved fluorescence techniques to distinguish chemical composition and structure modifications could assist develop a portable and non-destructive methodology to perform milk powder classification and determine composition. This study goal is to differentiate milk powder samples from cows and goats using fluorescence lifetimes. The samples were excited at 315 nm and the fluorescence intensity decay registered at 468 nm. We observed fluorescence lifetimes of 1.5 ± 0.3, 6.4 ± 0.4 and 18.7 ± 2.5 ns for goat milk powder; and 1.7 ± 0.3, 6.9 ± 0.2 and 29.9 ± 1.6 ns for cow's milk powder. We discriminate goat and cow powder milk by analysis of variance using Fisher's method. In addition, we employed quadratic discriminant analysis to differentiate the milk samples with accuracy of 100%. Our results suggest that time-resolved fluorescence can provide a new method to the analysis of powder milk and its composition.

  2. Time-resolved single dopant charge dynamics in silicon

    PubMed Central

    Rashidi, Mohammad; Burgess, Jacob A. J.; Taucer, Marco; Achal, Roshan; Pitters, Jason L.; Loth, Sebastian; Wolkow, Robert A.

    2016-01-01

    As the ultimate miniaturization of semiconductor devices approaches, it is imperative that the effects of single dopants be clarified. Beyond providing insight into functions and limitations of conventional devices, such information enables identification of new device concepts. Investigating single dopants requires sub-nanometre spatial resolution, making scanning tunnelling microscopy an ideal tool. However, dopant dynamics involve processes occurring at nanosecond timescales, posing a significant challenge to experiment. Here we use time-resolved scanning tunnelling microscopy and spectroscopy to probe and study transport through a dangling bond on silicon before the system relaxes or adjusts to accommodate an applied electric field. Atomically resolved, electronic pump-probe scanning tunnelling microscopy permits unprecedented, quantitative measurement of time-resolved single dopant ionization dynamics. Tunnelling through the surface dangling bond makes measurement of a signal that would otherwise be too weak to detect feasible. Distinct ionization and neutralization rates of a single dopant are measured and the physical process controlling those are identified. PMID:27782125

  3. Formulation for Time-resolved Aerodynamic Damping in Dynamic Stall

    NASA Astrophysics Data System (ADS)

    Corke, Thomas; Bowles, Patrick; Coleman, Dusty; Thomas, Flint

    2012-11-01

    A new Hilbert transform formulation of the equation of motion for a pitching airfoil in a uniform stream yields a time resolved aerodynamic damping factor, Ξ (t) = (√{ (Cm2 (t) +C m2 } /αmax) sinψ (t) , where Cm (t) is the instantaneous pitch moment coefficient, and C m (t) is the Hilbert transform of Cm (t) , αmax is the pitching amplitude, and ψ (t) is the time-resolved phase difference between the aerodynamic pitch moment and the instantaneous angle of attack. A Ξ (t) < 0 indicates unstable pressure loading that can be considered a necessary condition to excite stall flutter in an elastic airfoil. This will be illustrated in experiments with conditions producing ``light'' dynamic stall for a range of Mach numbers from 0.3-0.6. These reveal large negative excursions of Ξ (t) during the pitch-up portion of the cycle that correlates with the formation and convection of the dynamic stall vortex. The fact that the cycle-integrated damping coefficient is positive in all these cases underscores how the traditional diagnostic masks much of the physics that underlies the destabilizing effect of the dynamic stall process. This new insight can explain instances of transient limit-cycle growth of helicopter rotor vibrations. Supported by Bell Helicopter.

  4. Time resolved imaging microscopy. Phosphorescence and delayed fluorescence imaging.

    PubMed Central

    Marriott, G; Clegg, R M; Arndt-Jovin, D J; Jovin, T M

    1991-01-01

    An optical microscope capable of measuring time resolved luminescence (phosphorescence and delayed fluorescence) images has been developed. The technique employs two phase-locked mechanical choppers and a slow-scan scientific CCD camera attached to a normal fluorescence microscope. The sample is illuminated by a periodic train of light pulses and the image is recorded within a defined time interval after the end of each excitation period. The time resolution discriminates completely against light scattering, reflection, autofluorescence, and extraneous prompt fluorescence, which ordinarily decrease contrast in normal fluorescence microscopy measurements. Time resolved image microscopy produces a high contrast image and particular structures can be emphasized by displaying a new parameter, the ratio of the phosphorescence to fluorescence. Objects differing in luminescence decay rates are easily resolved. The lifetime of the long lived luminescence can be measured at each pixel of the microscope image by analyzing a series of images that differ by a variable time delay. The distribution of luminescence decay rates is displayed directly as an image. Several examples demonstrate the utility of the instrument and the complementarity it offers to conventional fluorescence microscopy. Images FIGURE 2 FIGURE 3 FIGURE 4 FIGURE 5 FIGURE 6 PMID:1723311

  5. Motor Oil Classification Based on Time-Resolved Fluorescence

    PubMed Central

    Mu, Taotao; Chen, Siying; Zhang, Yinchao; Guo, Pan; Chen, He; Meng, Fandong

    2014-01-01

    A time-resolved fluorescence (TRF) technique is presented for classifying motor oils. The system is constructed with a third harmonic Nd:YAG laser, a spectrometer, and an intensified charge coupled device (ICCD) camera. Steady-state and time-resolved fluorescence (TRF) measurements are reported for several motor oils. It is found that steady-state fluorescence is insufficient to distinguish the motor oil samples. Then contour diagrams of TRF intensities (CDTRFIs) are acquired to serve as unique fingerprints to identify motor oils by using the distinct TRF of motor oils. CDTRFIs are preferable to steady-state fluorescence spectra for classifying different motor oils, making CDTRFIs a particularly choice for the development of fluorescence-based methods for the discrimination and characterization of motor oils. The two-dimensional fluorescence contour diagrams contain more information, not only the changing shapes of the LIF spectra but also the relative intensity. The results indicate that motor oils can be differentiated based on the new proposed method, which provides reliable methods for analyzing and classifying motor oils. PMID:24988439

  6. CCD time-resolved photometry of faint cataclysmic variables. II

    SciTech Connect

    Szkody, P.; Howell, S.B.; Mateo, M.; Kreidl, T.J. Planetary Science Institute, Tucson, AZ Mount Wilson and Las Campanas Observatories, Pasadena, CA Lowell Observatory, Flagstaff, AZ )

    1989-10-01

    Time-resolved optical broad-band light curves obtained from differential photometry on sequential CCD frames of the known or suspected cataclysmic variable FO And, EH Aqr, WX Cet, XX Cet, AL Com, V503 Cyg, AH Eri, CP Eri, IR Gem, RW UMi, PG0134+070, and US 3215 are presented. The analysis of the light curves with coverage of greater than 2 hrs shows repeatable periodicity in five objects. PG0134+070 exhibits eclipses of 1.3-1.8 mag depth with a period of 313 min. V503 Cyg has a 0.7-1.0 mag peak-to-peak modulation with a period of 109 min. IR Gem shows a large modulation at the orbital period of 99 min, and comparison with previous data indicates that this modulation may have an amplitude dependent on outburst phase. AH Eri reveals a 0.1-0.3 mag modulation, at a period of 42 min. Better time-resolved data on AL Com confirm the 0.4-mag variation reported by Howell and Szkody (1988) at a period of 42 min. These latter two short periods likely indicate magnetic systems. There is also some evidence of periodicity in RW UMi and WX Cet which must be confirmed with further data. 25 refs.

  7. Recent applications of multiwire proportional chambers for time resolved studies on muscle

    NASA Astrophysics Data System (ADS)

    Faruqi, A. R.; Huxley, H. E.; Kress, M.

    1986-12-01

    The use of multiwire proportional chambers has played an important role in recording time resolved data from vertebrate muscle under various physiological conditions from which we have selected two examples from recent work. The first example describes the measurement of the equatorial pattern along with measurements of the muscle sarcomere length showing that the delay in tension development relative to changes in the X-ray intensity are not due to "internal" shortening in the muscle. The second example describes time-resolved measurements on the thin filament activation process, studied with both a linear and an area detector. The results show clearly that changes in thin filament structure precede cross-bridge formation producing further strong evidence for the "steric blocking model" for muscle contraction.

  8. A Validation Study of a Novel 3-Dimensional MRI Modeling Technique to Identify the Anatomic Insertions of the Anterior Cruciate Ligament

    PubMed Central

    Hui, Catherine; Pi, Yeli; Swami, Vimarsha; Mabee, Myles; Jaremko, Jacob L.

    2016-01-01

    Background: Anatomic single bundle anterior cruciate ligament (ACL) reconstruction is the current gold standard in ACL reconstructive surgery. However, placement of femoral and tibial tunnels at the anatomic center of the ACL insertion sites can be difficult intraoperatively. We developed a “virtual arthroscopy” program that allows users to identify ACL insertions on preoperative knee magnetic resonance images (MRIs) and generates a 3-dimensional (3D) bone model that matches the arthroscopic view to help guide intraoperative tunnel placement. Purpose: To test the validity of the ACL insertion sites identified using our 3D modeling program and to determine the accuracy of arthroscopic ACL reconstruction guided by our “virtual arthroscopic” model. Study Design: Descriptive laboratory study. Methods: Sixteen cadaveric knees were prescanned using routine MRI sequences. A trained, blinded observer then identified the center of the ACL insertions using our program. Eight knees were dissected, and the centers of the ACL footprints were marked with a screw. In the remaining 8 knees, arthroscopic ACL tunnels were drilled into the center of the ACL footprints based on landmarks identified using our virtual arthroscopic model. Postprocedural MRI was performed on all 16 knees. The 3D distance between pre- and postoperative 3D centers of the ACL were calculated by 2 trained, blinded observers and a musculoskeletal radiologist. Results: With 2 outliers removed, the postoperative femoral and tibial tunnel placements in the open specimens differed by 2.5 ± 0.9 mm and 2.9 ± 0.7 mm from preoperative centers identified on MRI. Postoperative femoral and tibial tunnel centers in the arthroscopic specimens differed by 3.2 ± 0.9 mm and 2.9 ± 0.7 mm, respectively. Conclusion: Our results show that MRI-based 3D localization of the ACL and our virtual arthroscopic modeling program is feasible and does not show a statistically significant difference to an open arthrotomy approach

  9. Spectral characteristics of time resolved magnonic spin Seebeck effect

    SciTech Connect

    Etesami, S. R.; Chotorlishvili, L.; Berakdar, J.

    2015-09-28

    Spin Seebeck effect (SSE) holds promise for new spintronic devices with low-energy consumption. The underlying physics, essential for a further progress, is yet to be fully clarified. This study of the time resolved longitudinal SSE in the magnetic insulator yttrium iron garnet concludes that a substantial contribution to the spin current stems from small wave-vector subthermal exchange magnons. Our finding is in line with the recent experiment by S. R. Boona and J. P. Heremans [Phys. Rev. B 90, 064421 (2014)]. Technically, the spin-current dynamics is treated based on the Landau-Lifshitz-Gilbert equation also including magnons back-action on thermal bath, while the formation of the time dependent thermal gradient is described self-consistently via the heat equation coupled to the magnetization dynamics.

  10. Time-resolved thermal transport in compositionally modulated metal films

    SciTech Connect

    Clemens, B.M.; Eesley, G.L.; Paddock, C.A.

    1988-01-15

    We report on investigations of one-dimensional thermal transport in compositionally modulated metal films produced with a systematic variation in atomic lattice mismatch. In the case of Ni-Cu, Ni-Mo, Ni-Ti, and Ni-Zr, we observe the relative effects of interfacial disorder on thermal diffusion. Our observations demonstrate the thermal impedance of a single metal-metal interface and indicate that thermal diffusion in a bilayer film is strongly influenced by the interface between contacting metal pairs. This study is made possible by picosecond time-resolved thermoreflectance measurements which probe thermal transport perpendicular to the film plane. This technique can impact on our understanding of electron scattering and transport across metallic boundaries, and it provides a means of inferring electrical transport properties.

  11. Photon-Counting Arrays for Time-Resolved Imaging

    PubMed Central

    Antolovic, I. Michel; Burri, Samuel; Hoebe, Ron A.; Maruyama, Yuki; Bruschini, Claudio; Charbon, Edoardo

    2016-01-01

    The paper presents a camera comprising 512 × 128 pixels capable of single-photon detection and gating with a maximum frame rate of 156 kfps. The photon capture is performed through a gated single-photon avalanche diode that generates a digital pulse upon photon detection and through a digital one-bit counter. Gray levels are obtained through multiple counting and accumulation, while time-resolved imaging is achieved through a 4-ns gating window controlled with subnanosecond accuracy by a field-programmable gate array. The sensor, which is equipped with microlenses to enhance its effective fill factor, was electro-optically characterized in terms of sensitivity and uniformity. Several examples of capture of fast events are shown to demonstrate the suitability of the approach. PMID:27367697

  12. Multidimensional Time-Resolved Spectroscopy of Vibrational Coherence in Biopolyenes

    NASA Astrophysics Data System (ADS)

    Buckup, Tiago; Motzkus, Marcus

    2014-04-01

    Multidimensional femtosecond time-resolved vibrational coherence spectroscopy allows one to investigate the evolution of vibrational coherence in electronic excited states. Methods such as pump-degenerate four-wave mixing and pump-impulsive vibrational spectroscopy combine an initial ultrashort laser pulse with a nonlinear probing sequence to reinduce vibrational coherence exclusively in the excited states. By carefully exploiting specific electronic resonances, one can detect vibrational coherence from 0 cm-1 to over 2,000 cm-1 and map its evolution. This review focuses on the observation and mapping of high-frequency vibrational coherence for all-trans biological polyenes such as β-carotene, lycopene, retinal, and retinal Schiff base. We discuss the role of molecular symmetry in vibrational coherence activity in the S1 electronic state and the interplay of coupling between electronic states and vibrational coherence.

  13. Time-resolved polarization study of anisotropy in bacteriorhodopsin

    SciTech Connect

    Wan, Chaozhi; Qian, Jun; Johnson, C.K. )

    1990-11-01

    Time-resolved polarization spectroscopy is sensitive to the orientational dynamics of chromophores, and as a result it can be applied to study internal motion in restrictive environments. This paper describes the application of polarization spectroscopy to the photoactive protein bacteriorhodopsin on time scales from picoseconds to hundreds of microseconds. Anisotropy persists in both the ground-state bacteriorhodopsin population and in the photocycle intermediates due to a population bottleneck in the bacteriorhodopsin photocycle. The time dependence of the polarization signal expected for a sequence of intermediates is described and is shown to be sensitive both to population kinetics and to internal motion. The observed time dependence of the polarization signal reveals internal motion in the purple membrane fragments on the time scale of the K {yields} L transition ({approximately} 1 {mu}s). The results are consistent with the known kinetics of the bacteriorhodopsin photocycle. Evidence is also presented and discussed for a decay component on a time scale of < 50 ps.

  14. Revealing Deactivation Pathways Hidden in Time-Resolved Photoelectron Spectra

    NASA Astrophysics Data System (ADS)

    Ruckenbauer, Matthias; Mai, Sebastian; Marquetand, Philipp; González, Leticia

    2016-10-01

    Time-resolved photoelectron spectroscopy is commonly employed with the intention to monitor electronic excited-state dynamics occurring in a neutral molecule. With the help of theory, we show that when excited-state processes occur on similar time scales the different relaxation pathways are completely obscured in the total photoionization signal recorded in the experiment. Using non-adiabatic molecular dynamics and Dyson norms, we calculate the photoionization signal of cytosine and disentangle the transient contributions originating from the different deactivation pathways of its tautomers. In the simulations, the total signal from the relevant keto and enol tautomers can be decomposed into contributions either from the neutral electronic state populations or from the distinct mechanistic pathways across the multiple potential surfaces. The lifetimes corresponding to these contributions cannot be extracted from the experiment, thereby illustrating that new experimental setups are necessary to unravel the intricate non-adiabatic pathways occurring in polyatomic molecules after irradiation by light.

  15. Nonselective and polarization effects in time-resolved optogalvanic spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhechev, D.; Steflekova, V.

    2016-02-01

    Three interfering effects in optogalvanic (OG) spectroscopy are identified in a hollow cathode discharge (HCD) - OG detector. The laser beam is found to generate two nonselective processes, namely photoelectron emission (PE) from the cathode surface with a sub-breakdown bias applied, and nonresonant space ionization. The convolution of these galvanic contributions was determined experimentally as an instrumental function and a deconvolution procedure to determine the actual OG signal was developed. Specific plasma conductance is detected dependent on the polarization of the laser beam irradiating. Linearly/circularly polarized light beam is found to induce OG signals differ in amplitude (and their shape parameters in the time-resolved OG signals (TROGS)). The phenomena coherence and specific conductance are found to be in causal relationship. The additional conductance due to coherent states of atoms manifests itself as an intrinsic instrumental property of OG detector.

  16. Towards time-resolved serial crystallography in a microfluidic device

    PubMed Central

    Pawate, Ashtamurthy S.; Šrajer, Vukica; Schieferstein, Jeremy; Guha, Sudipto; Henning, Robert; Kosheleva, Irina; Schmidt, Marius; Ren, Zhong; Kenis, Paul J. A.; Perry, Sarah L.

    2015-01-01

    Serial methods for crystallography have the potential to enable dynamic structural studies of protein targets that have been resistant to single-crystal strategies. The use of serial data-collection strategies can circumvent challenges associated with radiation damage and repeated reaction initiation. This work utilizes a microfluidic crystallization platform for the serial time-resolved Laue diffraction analysis of macroscopic crystals of photoactive yellow protein (PYP). Reaction initiation was achieved via pulsed laser illumination, and the resultant electron-density difference maps clearly depict the expected pR1/pRE46Q and pR2/pRCW states at 10 µs and the pB1 intermediate at 1 ms. The strategies presented here have tremendous potential for extension to chemical triggering methods for reaction initiation and for extension to dynamic, multivariable analyses. PMID:26144226

  17. Fast Time-Resolved Aerosol Collector: Proof of Concept

    SciTech Connect

    Yu, Xiao-Ying; Cowin, James P.; Iedema, Martin J.; Ali, Hashim M.

    2010-10-12

    Atmospheric particles can be collected in the field on substrates for subsequent laboratory analysis via chemically sensitive single particle methods such as scanning electron microscopy with energy dispersed x-ray analysis. With moving substrates one can achieve time resolution of seconds to minutes. We demonstrate how to increase the time resolution to a few milliseconds to provide real-time information in this paper. Our fast time-resolved aerosol collector (“Fast-TRAC”) microscopically observes the particle collection on substrate and record an on-line video. Particle arrivals are resolved to within a single frame (17 to 4 ms in this setup), and the spatial locations are matched to the subsequent single particle analysis. This approach provides real-time information on particle size and number concentration. Applications are expected in airborne studies of cloud microstructure, pollution plumes, and long term site monitoring.

  18. Spectral characteristics of time resolved magnonic spin Seebeck effect

    NASA Astrophysics Data System (ADS)

    Etesami, S. R.; Chotorlishvili, L.; Berakdar, J.

    2015-09-01

    Spin Seebeck effect (SSE) holds promise for new spintronic devices with low-energy consumption. The underlying physics, essential for a further progress, is yet to be fully clarified. This study of the time resolved longitudinal SSE in the magnetic insulator yttrium iron garnet concludes that a substantial contribution to the spin current stems from small wave-vector subthermal exchange magnons. Our finding is in line with the recent experiment by S. R. Boona and J. P. Heremans [Phys. Rev. B 90, 064421 (2014)]. Technically, the spin-current dynamics is treated based on the Landau-Lifshitz-Gilbert equation also including magnons back-action on thermal bath, while the formation of the time dependent thermal gradient is described self-consistently via the heat equation coupled to the magnetization dynamics.

  19. Revealing Deactivation Pathways Hidden in Time-Resolved Photoelectron Spectra

    PubMed Central

    Ruckenbauer, Matthias; Mai, Sebastian; Marquetand, Philipp; González, Leticia

    2016-01-01

    Time-resolved photoelectron spectroscopy is commonly employed with the intention to monitor electronic excited-state dynamics occurring in a neutral molecule. With the help of theory, we show that when excited-state processes occur on similar time scales the different relaxation pathways are completely obscured in the total photoionization signal recorded in the experiment. Using non-adiabatic molecular dynamics and Dyson norms, we calculate the photoionization signal of cytosine and disentangle the transient contributions originating from the different deactivation pathways of its tautomers. In the simulations, the total signal from the relevant keto and enol tautomers can be decomposed into contributions either from the neutral electronic state populations or from the distinct mechanistic pathways across the multiple potential surfaces. The lifetimes corresponding to these contributions cannot be extracted from the experiment, thereby illustrating that new experimental setups are necessary to unravel the intricate non-adiabatic pathways occurring in polyatomic molecules after irradiation by light. PMID:27762396

  20. Time-resolved measurements of equilibrium profiles in MST

    NASA Astrophysics Data System (ADS)

    Deng, B. H.; Brower, D. L.; Ding, W. X.; Yates, T. F.; Anderson, J. K.; Caspary, K.; McCollam, K. J.; Prager, S. C.; Reusch, J. A.; Sarff, J. S.; Craig, D.

    2007-11-01

    Based on the high-speed, three-wave, far-infrared polarimeter-interferometer measurement of Bpol profiles and external coil measurements of Btave and Btw, a new method is developed to derive Btor and other equilibrium profiles (J// and q) with high time resolution. Using Faraday's law, the inductive electric field (E//) profile is also deduced from the temporal derivatives of the time-resolved magnetic field profiles. The derived B(0) values have excellent agreement with direct measurements using a Motional Stark Effect (MSE) diagnostic. Evolution of equilibrium profiles during single sawtooth events in MST, both the slow linear ramp and crash phases, are presented. Profile scaling with plasma current Ip and reversal parameter F is also explored. MHD stability is tested from the spatial gradients of the J// and q profiles, and correlation with fluctuation mode amplitude is investigated. Future improvements to equilibrium reconstruction are expected by measuring Btor(r,t) directly via Cotton-Mouton interferometry.

  1. Time-resolved phase-sensitive second harmonic generation spectroscopy

    NASA Astrophysics Data System (ADS)

    Nowakowski, Paweł J.; Woods, David A.; Bain, Colin D.; Verlet, Jan R. R.

    2015-02-01

    A methodology based on time-resolved, phase-sensitive second harmonic generation (SHG) for probing the excited state dynamics of species at interfaces is presented. It is based on an interference measurement between the SHG from the sample and a local oscillator generated at a reference together with a lock-in measurement to remove the large constant offset from the interference. The technique is characterized by measuring the phase and excited state dynamics of the dye malachite green at the water/air interface. The key attributes of the technique are that the observed signal is directly proportional to sample concentration, in contrast to the quadratic dependence from non-phase sensitive SHG, and that the real and imaginary parts of the 2nd order non-linear susceptibility can be determined independently. We show that the method is highly sensitive and can provide high quality excited state dynamics in short data acquisition times.

  2. Time-resolve study of the photooxygenation of 3-hydroxyflavone

    SciTech Connect

    Studer, S.L.; Brewer, W.E.; Martinez, M.L.; Chou, Pi-Tai )

    1989-09-13

    3-hydroxyflavones are prototype molecules for studying the dynamics of the proton-transfer reaction in the excited state as well as in the ground state. Their lasing action has been reported with a high efficiency of laser gain. Unfortunately, a major obstruction to the practical application of 3-hydroxy-flavones as laser dyes is due to a photochemical reaction possibly involving molecular oxygen. In this communication we report a direct time-resolved study of the photooxygenation of 3-hydroxyflavone (3HF) in the normal state as well as in the tau-tomer state. Our results not only provide a detailed mechanism of the photooxygenation reaction but also give indirect evidence to support the role of the triplet state in the reverse proton-transfer reaction.

  3. Towards time-resolved serial crystallography in a microfluidic device.

    PubMed

    Pawate, Ashtamurthy S; Šrajer, Vukica; Schieferstein, Jeremy; Guha, Sudipto; Henning, Robert; Kosheleva, Irina; Schmidt, Marius; Ren, Zhong; Kenis, Paul J A; Perry, Sarah L

    2015-07-01

    Serial methods for crystallography have the potential to enable dynamic structural studies of protein targets that have been resistant to single-crystal strategies. The use of serial data-collection strategies can circumvent challenges associated with radiation damage and repeated reaction initiation. This work utilizes a microfluidic crystallization platform for the serial time-resolved Laue diffraction analysis of macroscopic crystals of photoactive yellow protein (PYP). Reaction initiation was achieved via pulsed laser illumination, and the resultant electron-density difference maps clearly depict the expected pR(1)/pR(E46Q) and pR(2)/pR(CW) states at 10 µs and the pB1 intermediate at 1 ms. The strategies presented here have tremendous potential for extension to chemical triggering methods for reaction initiation and for extension to dynamic, multivariable analyses.

  4. Femtosecond time-resolved ERE-CARS of PM650

    NASA Astrophysics Data System (ADS)

    He, Ping; Fan, Rongwei; Chen, Deying; Li, Xiaohui; Xia, Yuanqin; Yu, Xin; Wang, Jialing; Jiang, Yugang

    2012-07-01

    We utilize femtosecond time-resolved electronic resonance-enhanced coherent anti-Stokes Raman scattering (ERE-CARS) to investigate new information for pyrromethene 650 (PM650) dye molecules. For this purpose, the vibrational properties of PM650 are registered in diluted solutions of several organisms. We observe a strong Raman vibrational mode with a wavenumber difference of about 48 cm- 1 in its organic solutions. This may be linked to the intramolecular electron transfer (ICT) process from the aromatic ring to the cyano group in PM650. The influence of the solvent effects on the vibrational dynamics of PM650 is also investigated. The vibrational properties of PM650 dye molecules diluted in polar organic solutions are light solvent-dependent.

  5. Time-Resolved Infrared (TRIR) Studies of Oxycarbonylnitrenes.

    PubMed

    Chavez, Tyler A; Liu, Yonglin; Toscano, John P

    2016-08-05

    N-Ethyloxycarbonyl-S,S-dibenzothiphene sulfilimine and N-t-butyloxycarbonyl-S,S-dibenzothiphene sulfilimine have been utilized as precursors to ethoxycarbonylnitrene and t-butyloxycarbonylnitrene. B3LYP/6-31G(d) calculations predict triplet ground states for both oxycarbonylnitrenes, albeit by small margins. Triplet ethoxycarbonylnitrene and triplet t-butyloxycarbonylnitrene have been observed following photolysis of these sulfilimine precursors by time-resolved infrared (TRIR) spectroscopy. Kinetic studies show that ethoxycarbonylnitrene reacts with solvents such as acetonitrile and cyclohexane, while t-butyloxycarbonylnitrene undergoes an intramolecular insertion reaction to produce 5,5-dimethyl oxazolidinone. Product analysis following photolysis of N-t-butyloxycarbonyl-S,S-dibenzothiphene sulfilimine confirms that the oxazolidinone is the major product with an estimated yield of 90%. The products from these two nitrenes are derived from the corresponding singlet nitrene, either directly or via thermal repopulation of the singlet from the lower-energy triplet nitrene.

  6. Time-resolved, dual heterodyne phase collection transient grating spectroscopy

    NASA Astrophysics Data System (ADS)

    Dennett, Cody A.; Short, Michael P.

    2017-05-01

    The application of optical heterodyne detection for transient grating spectroscopy (TGS) using a fixed, binary phase mask often relies on taking the difference between signals captured at multiple heterodyne phases. To date, this has been accomplished by manually controlling the heterodyne phase between measurements with an optical flat. In this letter, an optical configuration is presented which allows for collection of TGS measurements at two heterodyne phases concurrently through the use of two independently phase controlled interrogation paths. This arrangement allows for complete, heterodyne amplified TGS measurements to be made in a manner not constrained by a mechanical actuation time. Measurements are instead constrained only by the desired signal-to-noise ratio. A temporal resolution of between 1 and 10 s, demonstrated here on single crystal metallic samples, will allow TGS experiments to be used as an in-situ, time-resolved monitoring technique for many material processing applications.

  7. Theoretical Studies of Time-Resolved Photoelectron Spectra of IBr^-

    NASA Astrophysics Data System (ADS)

    Horvath, Samantha; McCoy, Anne B.; Pitzer, Russell M.

    2009-06-01

    In the present study, we examine the time-resolved photoelectron spectra of IBr^-. In the photodetachment studies performed by Sanov and co-workers and Lineberger and co-workers, the anionic species, prepared in its electronic ground state (^2Σ_{1/2}^+), is excited to either its \\Atilde' (^2Π_{3/2}) or \\Btilde (^2Σ_{1/2}^+) excited state, before electron photodetachment and dissociation on the \\Ctilde (^1Π_1) or higher-lying excited states of the neutral species, respectively. In this work, we use the electronic structure program Columbus to calculate the six lowest electronic states of IBr^- and the ten lowest Σ states of IBr at the MR-SO-CISD/aug-cc-pVDZ level of theory/basis, using relativistic core potentials for I and Br. Experimentally determined electronic states of IBr are also used. Vibrational eigenstates for these electronic states are calculated in a discrete variable representation, and propagation of the thermally populated \\Xtilde-state vibrational wave functions on either the \\Atilde' or \\Btilde electronic states of the anion is performed using a Lanczos scheme. We then take time-dependent overlaps between these propagated states and the vibrational eigenstates of the neutral surface. Results for IBr^- show good agreement with the experimental time-resolved spectra. Extensions to IBr^-(CO_2)_n (n < 2) will also be discussed. R. Mabbs, K. Pichugin, and A. Sanov, J. Chem. Phys., 2005 122, 174305 Leonid Sheps, Elisa M. Miller, and W. C. Lineberger (private communication) E. Wrede, S. Laubach, S. Schulenburg, A. Brown, E. R. Wouters, A. J. Orr-Ewing, and M. N. R. Ashfold, J. Chem. Phys., 2001, 114(6), 2629. D. T. Colbert and W. H. Miller, J. Chem. Phys., 1992, 96(3), 1982

  8. Rigorous 3-dimensional spectral data activity relationship approach modeling strategy for ToxCast estrogen receptor data classification, validation, and feature extraction.

    PubMed

    Slavov, Svetoslav H; Beger, Richard D

    2017-03-01

    The estrogenic potential (expressed as a score composite of 18 high throughput screening bioassays) of 1528 compounds from the ToxCast database was modeled by a 3-dimensional spectral data activity relationship approach (3D-SDAR). Due to a lack of (17) O nuclear magnetic resonance (NMR) simulation software, the most informative carbon-carbon 3D-SDAR fingerprints were augmented with indicator variables representing oxygen atoms from carbonyl and carboxamide, ester, sulfonyl, nitro, aliphatic hydroxyl, and phenolic hydroxyl groups. To evaluate the true predictive performance of the authors' model the United States Environmental Protection Agency provided them with a blind test set consisting of 2008 compounds. Of these, 543 had available literature data-their binding affinity served to estimate the external classification accuracy of the developed model: predictive accuracy of 0.62, sensitivity of 0.71, and specificity of 0.53 were obtained. Compared with alternative modeling techniques, the authors' model displayed very little reduction in performance between the modeling and the prediction set. A 3D-SDAR mapping technique allowed identification of structural features essential for estrogenicity: 1) the presence of a phenolic OH group or cyclohexenone, 2) a second aromatic or phenolic ring at a distance of 6 Å to 8 Å from the oxygen of the first phenol ring, 3) the presence of a methyl group approximately 6 Å away from the centroid of a phenol ring, and 4) a carbonyl group in close proximity (∼4 Å measured to the centroid) to 1 of the phenol rings. Environ Toxicol Chem 2017;36:823-830. Published 2016 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America. Published 2016 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

  9. Evaluating scintillator performance in time-resolved hard X-ray studies at synchrotron light sources

    PubMed Central

    Rutherford, Michael E.; Chapman, David J.; White, Thomas G.; Drakopoulos, Michael; Rack, Alexander; Eakins, Daniel E.

    2016-01-01

    The short pulse duration, small effective source size and high flux of synchrotron radiation is ideally suited for probing a wide range of transient deformation processes in materials under extreme conditions. In this paper, the challenges of high-resolution time-resolved indirect X-ray detection are reviewed in the context of dynamic synchrotron experiments. In particular, the discussion is targeted at two-dimensional integrating detector methods, such as those focused on dynamic radiography and diffraction experiments. The response of a scintillator to periodic synchrotron X-ray excitation is modelled and validated against experimental data collected at the Diamond Light Source (DLS) and European Synchrotron Radiation Facility (ESRF). An upper bound on the dynamic range accessible in a time-resolved experiment for a given bunch separation is calculated for a range of scintillators. New bunch structures are suggested for DLS and ESRF using the highest-performing commercially available crystal LYSO:Ce, allowing time-resolved experiments with an interframe time of 189 ns and a maximum dynamic range of 98 (6.6 bits). PMID:27140147

  10. Particle tracking during Ostwald ripening using time-resolved laboratory X-ray microtomography

    SciTech Connect

    Werz, T.; Baumann, M.; Wolfram, U.; Krill, C.E.

    2014-04-01

    Laboratory X-ray microtomography is investigated as a method for obtaining time-resolved images of microstructural coarsening of the semisolid state of Al–5 wt.% Cu samples during Ostwald ripening. Owing to the 3D imaging capability of tomography, this technique uniquely provides access to the growth rates of individual particles, thereby not only allowing a statistical characterization of coarsening—as has long been possible by conventional metallography—but also enabling quantification of the influence of local environment on particle boundary migration. The latter information is crucial to understanding growth kinetics during Ostwald ripening at high volume fractions of the coarsening phase. Automated image processing and segmentation routines were developed to close gaps in the network of particle boundaries and to track individual particles from one annealing step to the next. The particle tracking success rate places an upper bound of only a few percent on the likelihood of segmentation errors for any given particle. The accuracy of particle size trajectories extracted from the time-resolved tomographic reconstructions is correspondingly high. Statistically averaged coarsening data and individual particle growth rates are in excellent agreement with the results of prior experimental studies and with computer simulations of Ostwald ripening. - Highlights: • Ostwald ripening in Al–5 wt.% Cu measured by laboratory X-ray microtomography • Time-resolved measurement of individual particle growth • Automated segmentation routines developed to close gaps in particle boundary network • Particle growth/shrinkage rates deviate from LSW model prediction.

  11. Evaluating scintillator performance in time-resolved hard X-ray studies at synchrotron light sources.

    PubMed

    Rutherford, Michael E; Chapman, David J; White, Thomas G; Drakopoulos, Michael; Rack, Alexander; Eakins, Daniel E

    2016-05-01

    The short pulse duration, small effective source size and high flux of synchrotron radiation is ideally suited for probing a wide range of transient deformation processes in materials under extreme conditions. In this paper, the challenges of high-resolution time-resolved indirect X-ray detection are reviewed in the context of dynamic synchrotron experiments. In particular, the discussion is targeted at two-dimensional integrating detector methods, such as those focused on dynamic radiography and diffraction experiments. The response of a scintillator to periodic synchrotron X-ray excitation is modelled and validated against experimental data collected at the Diamond Light Source (DLS) and European Synchrotron Radiation Facility (ESRF). An upper bound on the dynamic range accessible in a time-resolved experiment for a given bunch separation is calculated for a range of scintillators. New bunch structures are suggested for DLS and ESRF using the highest-performing commercially available crystal LYSO:Ce, allowing time-resolved experiments with an interframe time of 189 ns and a maximum dynamic range of 98 (6.6 bits).

  12. Electron-transfer acceleration investigated by time resolved infrared spectroscopy.

    PubMed

    Vlček, Antonín; Kvapilová, Hana; Towrie, Michael; Záliš, Stanislav

    2015-03-17

    Ultrafast electron transfer (ET) processes are important primary steps in natural and artificial photosynthesis, as well as in molecular electronic/photonic devices. In biological systems, ET often occurs surprisingly fast over long distances of several tens of angströms. Laser-pulse irradiation is conveniently used to generate strongly oxidizing (or reducing) excited states whose reactions are then studied by time-resolved spectroscopic techniques. While photoluminescence decay and UV-vis absorption supply precise kinetics data, time-resolved infrared absorption (TRIR) and Raman-based spectroscopies have the advantage of providing additional structural information and monitoring vibrational energy flows and dissipation, as well as medium relaxation, that accompany ultrafast ET. We will discuss three cases of photoinduced ET involving the Re(I)(CO)3(N,N) moiety (N,N = polypyridine) that occur much faster than would be expected from ET theories. [Re(4-N-methylpyridinium-pyridine)(CO)3(N,N)](2+) represents a case of excited-state picosecond ET between two different ligands that remains ultrafast even in slow-relaxing solvents, beating the adiabatic limit. This is caused by vibrational/solvational excitation of the precursor state and participation of high-frequency quantum modes in barrier crossing. The case of Re-tryptophan assemblies demonstrates that excited-state Trp → *Re(II) ET is accelerated from nanoseconds to picoseconds when the Re(I)(CO)3(N,N) chromophore is appended to a protein, close to a tryptophan residue. TRIR in combination with DFT calculations and structural studies reveals an interaction between the N,N ligand and the tryptophan indole. It results in partial electronic delocalization in the precursor excited state and likely contributes to the ultrafast ET rate. Long-lived vibrational/solvational excitation of the protein Re(I)(CO)3(N,N)···Trp moiety, documented by dynamic IR band shifts, could be another accelerating factor. The last

  13. Time-Resolved Measurements of Carbon Nanotube and Nanohorn Growth

    NASA Astrophysics Data System (ADS)

    Geohegan, David

    2005-11-01

    Mechanisms for carbon nanotube growth have been investigated for both laser vaporization (LV) and chemical vapor deposition (CVD) synthesis techniques through the use of time-resolved, in situ laser-based diagnostics for the measurement of absolute growth rates. Optimization of both the production of loose single-wall carbon nanotubes (SWNTs) by LV and the sustained growth of mm-long, vertically-aligned carbon nanotube arrays (VANTAs) by CVD are described. For SWNT growth by laser co-vaporization of carbon and trace metal catalysts at high (1200 C) temperatures, nanotubes are found to grow at ˜ 1--5 microns/second to lengths of only several microns, as determined by gated-ICCD imaging and laser spectroscopy of the plume of ejected material. Efforts to scale the LV production of SWNTs utilizing an industrial Nd:YAG laser (600 W average power, 1-500 Hz repetition rate, 0.5-10ms pulse width) are described. In addition to vaporizing material at much higher rates, the high-power laser irradiation provides sufficient plasma plume density and temperature to enable the growth of novel single-wall carbon nanohorn (SWNH) structures without the need for metal catalysts in the target. Applications of these SWNH structures as metal catalyst supports will be discussed. Through the application of time-resolved reflectivity and direct imaging, CVD growth of VANTAs from hydrocarbon gases at sustained rates of 0.2 -- 0.5 microns/second have been directly measured over millimeters of length at lower (˜ 700 C) temperatures. Now, through a new laser-CVD setup at the ALPS (Advanced Laser Processing and Synthesis) facility at ORNL, high-power laser heating is being employed for the fast and position-controlled growth of carbon nanotubes on substrates. In situ fast optical pyrometry is employed to record the rapid thermal processing of metal-catalyst-prepared substrates to investigate the nucleation and early growth behavior of CVD-grown nanotubes. New nanotube growth and tunable Raman

  14. Cyclohexene Photo-oxidation over Vanadia Catalyst Analyzed by Time Resolved ATR-FT-IR Spectroscopy

    SciTech Connect

    Frei, Heinz; Mul, Guido; Wasylenko, Walter; Hamdy, M. Sameh; Frei, Heinz

    2008-06-04

    Vanadia was incorporated in the 3-dimensional mesoporous material TUD-1 with a loading of 2percent w/w vanadia. The performance in the selective photo-oxidation of liquid cyclohexene was investigated using ATR-FT-IR spectroscopy. Under continuous illumination at 458 nm a significant amount of product, i.e. cyclohexenone, was identified. This demonstrates for the first time that hydroxylated vanadia centers in mesoporous materials can be activated by visible light to induce oxidation reactions. Using the rapid scan method, a strong perturbation of the vanadyl environment could be observed in the selective oxidation process induced by a 458 nm laser pulse of 480 ms duration. This is proposed to be caused by interaction of the catalytic centre with a cyclohexenyl hydroperoxide intermediate. The restoration of the vanadyl environment could be kinetically correlated to the rate of formation of cyclohexenone, and is explained by molecular rearrangement and dissociation of the peroxide to ketone and water. The ketone diffuses away from the active center and ATR infrared probing zone, resulting in a decreasing ketone signal on the tens of seconds time scale after initiation of the photoreaction. This study demonstrates the high potential of time resolved ATR FT-IR spectroscopy for mechanistic studies of liquid phase reactions by monitoring not only intermediates and products, but by correlating the temporal behavior of these species to molecular changes of the vanadyl catalytic site.

  15. Prospective time-resolved LCA of fully electric supercap vehicles in Germany.

    PubMed

    Zimmermann, Benedikt M; Dura, Hanna; Baumann, Manuel J; Weil, Marcel R

    2015-07-01

    historic data appears to be unsuitable for providing realistic information on the future. The time-resolved LCA approach improves the assessment's robustness substantially, especially when nonlinear developments are foreseen in the future scenarios. This allows for a reduction of bias in LCA-based decision making. However, a deeper integration of time-resolved data in the life cycle inventory and the implementation of a more suitable software framework are desirable. The study describes how life cycle assessment's (LCA) robustness can be improved by respecting prospective fluctuations, like the transition of the German electricity mix, in the modeling of the life cycle inventory. It presents a feasible and rather simple process to add time-resolved data to LCA. The study selects 2 different future scenarios from important German studies and processes their data systematically to make them compatible with the requirements of a life cycle inventory. The use of external scenarios as basis for future-oriented LCA is reflected critically. A case study on electric mobility is presented and used to compare historic, prospective static, and prospective time-resolved electricity mix modeling approaches. The case study emphasizes the benefits of time-resolved LCA in direct comparison with the currently used approaches. © 2015 SETAC.

  16. Time-resolved spectral imaging: better photon economy, higher accuracy

    NASA Astrophysics Data System (ADS)

    Fereidouni, Farzad; Reitsma, Keimpe; Blab, Gerhard A.; Gerritsen, Hans C.

    2015-03-01

    Lifetime and spectral imaging are complementary techniques that offer a non-invasive solution for monitoring metabolic processes, identifying biochemical compounds, and characterizing their interactions in biological tissues, among other tasks. Newly developed instruments that perform time-resolved spectral imaging can provide even more information and reach higher sensitivity than either modality alone. Here we report a multispectral lifetime imaging system based on a field-programmable gate array (FPGA), capable of operating at high photon count rates (12 MHz) per spectral detection channel, and with time resolution of 200 ps. We performed error analyses to investigate the effect of gate width and spectral-channel width on the accuracy of estimated lifetimes and spectral widths. Temporal and spectral phasors were used for analysis of recorded data, and we demonstrated blind un-mixing of the fluorescent components using information from both modalities. Fractional intensities, spectra, and decay curves of components were extracted without need for prior information. We further tested this approach with fluorescently doubly-labeled DNA, and demonstrated its suitability for accurately estimating FRET efficiency in the presence of either non-interacting or interacting donor molecules.

  17. Monitoring tissue metabolism via time-resolved laser fluorescence

    NASA Astrophysics Data System (ADS)

    Maerz, Holger K.; Buchholz, Rainer; Emmrich, Frank; Fink, Frank; Geddes, Clive L.; Pfeifer, Lutz; Raabe, Ferdinand; Marx, Uwe

    1999-05-01

    Most assays for drug screening are monitoring the metabolism of cells by detecting the NADH content, which symbolize its metabolic activity, indirectly. Nowadays, the performance of a LASER enables us to monitor the metabolic state of mammalian cells directly and on-line by using time-resolved autofluorescence detection. Therefore, we developed in combination with tissue engineering, an assay for monitoring minor toxic effects of volatile organic compounds (VOC), which are accused of inducing Sick Building Syndrome (SBS). Furthermore, we used the Laserfluoroscope (LF) for pharmacological studies on human bone marrow in vitro with special interest in chemotherapy simulation. In cancer research and therapy, the effect of chemostatica in vitro in the so-called oncobiogram is being tested; up to now without great success. However, it showed among other things that tissue structure plays a vital role. Consequently, we succeeded in simulating a chemotherapy in vitro on human bone marrow. Furthermore, after tumor ektomy we were able to distinguish between tumoric and its surrounding healthy tissue by using the LF. With its sensitive detection of metabolic changes in tissues the LF enables a wide range of applications in biotechnology, e.g. for quality control in artificial organ engineering or biocompatability testing.

  18. Fielding of a time-resolved tomographic diagnostic

    SciTech Connect

    Daniel Frayer, Brian Cox, Wendi Dreesen, Douglas Johnson, Morris Kaufman

    2008-03-01

    A diagnostic instrument has been developed for the acquisition of high-speed time-resolved images at the Dual-Axis Radiographic Hydrodynamic Test (DARHT) Facility at Los Alamos National Laboratory. The instrument was developed in order to create time histories of the electron beam. Four discrete optical subsystems view Cerenkov light generated at an X-ray target inside of a vacuum envelope. Each system employs cylindrical optics to image light in one direction and collapse light in the orthogonal direction. Each of the four systems images and collapses in unique axes, thereby capturing unique information. Light along the imaging axis is relayed via optical fiber to streak cameras. A computer is used to reconstruct the original image from the four optically collapsed images. Due to DARHT’s adverse environment, the instrument can be operated remotely to adjust optical parameters and contains a subsystem for remote calibration. The instrument was deployed and calibrated, and has been used to capture and reconstruct images. Matters of alignment, calibration, control, resolution, adverse conditions and maintenance will be discussed.

  19. Chopper system for time resolved experiments with synchrotron radiation.

    PubMed

    Cammarata, Marco; Eybert, Laurent; Ewald, Friederike; Reichenbach, Wolfgang; Wulff, Michael; Anfinrud, Philip; Schotte, Friedrich; Plech, Anton; Kong, Qingyu; Lorenc, Maciej; Lindenau, Bernd; Räbiger, Jürgen; Polachowski, Stephan

    2009-01-01

    A chopper system for time resolved pump-probe experiments with x-ray beams from a synchrotron is described. The system has three parts: a water-cooled heatload chopper, a high-speed chopper, and a millisecond shutter. The chopper system, which is installed in beamline ID09B at the European Synchrotron Radiation Facility, provides short x-ray pulses for pump-probe experiments with ultrafast lasers. The chopper system can produce x-ray pulses as short as 200 ns in a continuous beam and repeat at frequencies from 0 to 3 kHz. For bunch filling patterns of the synchrotron with pulse separations greater than 100 ns, the high-speed chopper can isolate single 100 ps x-ray pulses that are used for the highest time resolution. A new rotor in the high-speed chopper is presented with a single pulse (100 ps) and long pulse (10 micros) option. In white beam experiments, the heatload of the (noncooled) high-speed chopper is lowered by a heatload chopper, which absorbs 95% of the incoming power without affecting the pulses selected by the high speed chopper.

  20. Time-Resolved Hard X-Ray Spectrometer

    SciTech Connect

    Kenneth Moya; Ian McKennaa; Thomas Keenana; Michael Cuneob

    2007-03-01

    Wired array studies are being conducted at the SNL Z accelerator to maximize the x-ray generation for inertial confinement fusion targets and high energy density physics experiments. An integral component of these studies is the characterization of the time-resolved spectral content of the x-rays. Due to potential spatial anisotropy in the emitted radiation, it is also critical to diagnose the time-evolved spectral content in a space-resolved manner. To accomplish these two measurement goals, we developed an x-ray spectrometer using a set of high-speed detectors (silicon PIN diodes) with a collimated field-of-view that converged on a 1-cm-diameter spot at the pinch axis. Spectral discrimination is achieved by placing high Z absorbers in front of these detectors. We built two spectrometers to permit simultaneous different angular views of the emitted radiation. Spectral data have been acquired from recent Z shots for the radial and polar views. UNSPEC1 has been adapted to analyze and unfold the measured data to reconstruct the x-ray spectrum. The unfold operator code, UFO2, is being adapted for a more comprehensive spectral unfolding treatment.

  1. Time resolved spectroscopic NMR imaging using hyperpolarized 129Xe

    NASA Astrophysics Data System (ADS)

    Han, S.; Kühn, H.; Häsing, F. W.; Münnemann, K.; Blümich, B.; Appelt, S.

    2004-04-01

    We have visualized the melting and dissolution processes of xenon (Xe) ice into different solvents using the methods of nuclear magnetic resonance (NMR) spectroscopy, imaging, and time resolved spectroscopic imaging by means of hyperpolarized 129Xe. Starting from the initial condition of a hyperpolarized solid Xe layer frozen on top of an ethanol (ethanol/water) ice block we measured the Xe phase transitions as a function of time and temperature. In the pure ethanol sample, pieces of Xe ice first fall through the viscous ethanol to the bottom of the sample tube and then form a thin layer of liquid Xe/ethanol. The xenon atoms are trapped in this liquid layer up to room temperature and keep their magnetization over a time period of 11 min. In the ethanol/water mixture (80 vol%/20%), most of the polarized Xe liquid first stays on top of the ethanol/water ice block and then starts to penetrate into the pores and cracks of the ethanol/water ice block. In the final stage, nearly all the Xe polarization is in the gas phase above the liquid and trapped inside the pores. NMR spectra of homogeneous samples of pure ethanol containing thermally polarized Xe and the spectroscopic images of the melting process show that very high concentrations of hyperpolarized Xe (about half of the density of liquid Xe) can be stored or delivered in pure ethanol.

  2. Femtosecond time-resolved MeV electron diffraction

    DOE PAGES

    Zhu, Pengfei; Zhu, Y.; Hidaka, Y.; ...

    2015-06-02

    We report the experimental demonstration of femtosecond electron diffraction using high-brightness MeV electron beams. High-quality, single-shot electron diffraction patterns for both polycrystalline aluminum and single-crystal 1T-TaS2 are obtained utilizing a 5 fC (~3 × 104 electrons) pulse of electrons at 2.8 MeV. The high quality of the electron diffraction patterns confirms that electron beam has a normalized emittance of ~50 nm rad. The transverse and longitudinal coherence length is ~11 and ~2.5 nm, respectively. The timing jitter between the pump laser and probe electron beam was found to be ~100 fs (rms). The temporal resolution is demonstrated by observing themore » evolution of Bragg and superlattice peaks of 1T-TaS2 following an 800 nm optical pump and was found to be 130 fs. Lastly, our results demonstrate the advantages of MeV electrons, including large elastic differential scattering cross-section and access to high-order reflections, and the feasibility of ultimately realizing below 10 fs time-resolved electron diffraction.« less

  3. Time-Resolved Synchronous Fluorescence for Biomedical Diagnosis

    PubMed Central

    Zhang, Xiaofeng; Fales, Andrew; Vo-Dinh, Tuan

    2015-01-01

    This article presents our most recent advances in synchronous fluorescence (SF) methodology for biomedical diagnostics. The SF method is characterized by simultaneously scanning both the excitation and emission wavelengths while keeping a constant wavelength interval between them. Compared to conventional fluorescence spectroscopy, the SF method simplifies the emission spectrum while enabling greater selectivity, and has been successfully used to detect subtle differences in the fluorescence emission signatures of biochemical species in cells and tissues. The SF method can be used in imaging to analyze dysplastic cells in vitro and tissue in vivo. Based on the SF method, here we demonstrate the feasibility of a time-resolved synchronous fluorescence (TRSF) method, which incorporates the intrinsic fluorescent decay characteristics of the fluorophores. Our prototype TRSF system has clearly shown its advantage in spectro-temporal separation of the fluorophores that were otherwise difficult to spectrally separate in SF spectroscopy. We envision that our previously-tested SF imaging and the newly-developed TRSF methods will combine their proven diagnostic potentials in cancer diagnosis to further improve the efficacy of SF-based biomedical diagnostics. PMID:26404289

  4. Time resolved EUV spectra from Zpinching capillary discharge plasma

    NASA Astrophysics Data System (ADS)

    Jancarek, Alexandr; Nevrkla, Michal; Nawaz, Fahad

    2015-09-01

    We developed symmetrically charged driver to obtain high voltage, high current Z-pinching capillary discharge. Plasma is created by up to 70 kA, 29 ns risetime current pulse passing through a 5 mm inner diameter, 224 mm long capillary filled with gas to initial pressure in the range of 1 kPa. Due to the low inductance design of the driver, the pinch is observable directly from the measured current curve. Time-integrated and time-resolved spectra of discharge plasma radiation are recorded together with the capillary current and analyzed. The most encouraging spectra were captured in the wavelength range 8.3 ÷ 14 nm. This spectral region contains nitrogen Balmer series lines including potentially lasing NVII 2 - 3 transition. Spectral lines are identified in the NIST database using the FLY kinetic code. The line of 13.38 nm wavelength, transition NVII 2 - 3, was observed in gated, and also in time-integrated spectra for currents >60 kA. This work has been supported by the Ministry of Education, Youth and Sports of the Czech Republic grants LG13029.

  5. Time-resolved infrared spectroscopic techniques as applied to channelrhodopsin

    PubMed Central

    Ritter, Eglof; Puskar, Ljiljana; Bartl, Franz J.; Aziz, Emad F.; Hegemann, Peter; Schade, Ulrich

    2015-01-01

    Among optogenetic tools, channelrhodopsins, the light gated ion channels of the plasma membrane from green algae, play the most important role. Properties like channel selectivity, timing parameters or color can be influenced by the exchange of selected amino acids. Although widely used, in the field of neurosciences for example, there is still little known about their photocycles and the mechanism of ion channel gating and conductance. One of the preferred methods for these studies is infrared spectroscopy since it allows observation of proteins and their function at a molecular level and in near-native environment. The absorption of a photon in channelrhodopsin leads to retinal isomerization within femtoseconds, the conductive states are reached in the microsecond time scale and the return into the fully dark-adapted state may take more than minutes. To be able to cover all these time regimes, a range of different spectroscopical approaches are necessary. This mini-review focuses on time-resolved applications of the infrared technique to study channelrhodopsins and other light triggered proteins. We will discuss the approaches with respect to their suitability to the investigation of channelrhodopsin and related proteins. PMID:26217670

  6. Femtosecond time-resolved MeV electron diffraction

    SciTech Connect

    Zhu, Pengfei; Zhu, Y.; Hidaka, Y.; Wu, L.; Cao, J.; Berger, H.; Geck, J.; Kraus, R.; Pjerov, S.; Shen, Y.; Tobey, R. I.; Hill, J. P.; Wang, X. J.

    2015-06-02

    We report the experimental demonstration of femtosecond electron diffraction using high-brightness MeV electron beams. High-quality, single-shot electron diffraction patterns for both polycrystalline aluminum and single-crystal 1T-TaS2 are obtained utilizing a 5 fC (~3 × 104 electrons) pulse of electrons at 2.8 MeV. The high quality of the electron diffraction patterns confirms that electron beam has a normalized emittance of ~50 nm rad. The transverse and longitudinal coherence length is ~11 and ~2.5 nm, respectively. The timing jitter between the pump laser and probe electron beam was found to be ~100 fs (rms). The temporal resolution is demonstrated by observing the evolution of Bragg and superlattice peaks of 1T-TaS2 following an 800 nm optical pump and was found to be 130 fs. Lastly, our results demonstrate the advantages of MeV electrons, including large elastic differential scattering cross-section and access to high-order reflections, and the feasibility of ultimately realizing below 10 fs time-resolved electron diffraction.

  7. Fielding of a Time-Resolved Tomographic Diagnostic

    SciTech Connect

    Daniel Frayer, Brian Cox, Wendi Dreesen, Douglas Johnson, Mike Jones, Morris Kaufman

    2008-09-11

    A diagnostic instrument has been developed for the acquisition of high-speed time-resolved images at the Dual-Axis Radiographic Hydrodynamic Test (DARHT) Facility at Los Alamos National Laboratory. The instrument was developed in order to create time histories of the electron beam. Four discrete optical subsystems view Cerenkov light generated at an x-ray target inside of a vacuum envelope. Each system employs cylindrical optics to image light in one direction and collapse light in the orthogonal direction. Each of the four systems images and collapses in unique axes, thereby capturing unique information. Light along the imaging axis is relayed via optical fiber to streak cameras. A computer is used to reconstruct the original image from the four optically collapsed images. Due to DARHT’s adverse environment, the instrument can be operated remotely to adjust optical parameters and contains a subsystem for remote calibration. The instrument was deployed and calibrated, and has been used to capture and reconstruct images. Matters of alignment, calibration, control, resolution, and adverse conditions will be discussed.

  8. Time-resolved pump-probe experiments at the LCLS

    SciTech Connect

    Glownia, James; Cryan, J.; Andreasson, J.; Belkacem, A.; Berrah, N.; Blaga, C.L.; Bostedt, C.; Bozek, J.; DiMauro, L.F.; Fang, L.; Frisch, J.; Gessner, O.; Guhr, M.; Hajdu, J.; Hertlein, M.P.; Hoener, M.; Huang, G.; Kornilov, O.; Marangos, J.P.; March, A.M.; McFarland, B.K.; /SLAC /Stanford U., Phys. Dept. /SLAC /IRAMIS, Saclay /Stanford U., Phys. Dept. /Georgia Tech /Argonne /Kansas State U. /SLAC /Stanford U., Phys. Dept. /SLAC /Stanford U., Appl. Phys. Dept. /Stanford U., Appl. Phys. Dept. /SLAC /LBNL /Argonne /SLAC /SLAC /Stanford U., Appl. Phys. Dept. /Stanford U., Phys. Dept.

    2011-08-12

    The first time-resolved x-ray/optical pump-probe experiments at the SLAC Linac Coherent Light Source (LCLS) used a combination of feedback methods and post-analysis binning techniques to synchronize an ultrafast optical laser to the linac-based x-ray laser. Transient molecular nitrogen alignment revival features were resolved in time-dependent x-ray-induced fragmentation spectra. These alignment features were used to find the temporal overlap of the pump and probe pulses. The strong-field dissociation of x-ray generated quasi-bound molecular dications was used to establish the residual timing jitter. This analysis shows that the relative arrival time of the Ti:Sapphire laser and the x-ray pulses had a distribution with a standard deviation of approximately 120 fs. The largest contribution to the jitter noise spectrum was the locking of the laser oscillator to the reference RF of the accelerator, which suggests that simple technical improvements could reduce the jitter to better than 50 fs.

  9. Time-resolved pump-probe experiments at the LCLS.

    PubMed

    Glownia, James M; Cryan, J; Andreasson, J; Belkacem, A; Berrah, N; Blaga, C I; Bostedt, C; Bozek, J; DiMauro, L F; Fang, L; Frisch, J; Gessner, O; Gühr, M; Hajdu, J; Hertlein, M P; Hoener, M; Huang, G; Kornilov, O; Marangos, J P; March, A M; McFarland, B K; Merdji, H; Petrovic, V S; Raman, C; Ray, D; Reis, D A; Trigo, M; White, J L; White, W; Wilcox, R; Young, L; Coffee, R N; Bucksbaum, P H

    2010-08-16

    The first time-resolved x-ray/optical pump-probe experiments at the SLAC Linac Coherent Light Source (LCLS) used a combination of feedback methods and post-analysis binning techniques to synchronize an ultrafast optical laser to the linac-based x-ray laser. Transient molecular nitrogen alignment revival features were resolved in time-dependent x-ray-induced fragmentation spectra. These alignment features were used to find the temporal overlap of the pump and probe pulses. The strong-field dissociation of x-ray generated quasi-bound molecular dications was used to establish the residual timing jitter. This analysis shows that the relative arrival time of the Ti:Sapphire laser and the x-ray pulses had a distribution with a standard deviation of approximately 120 fs. The largest contribution to the jitter noise spectrum was the locking of the laser oscillator to the reference RF of the accelerator, which suggests that simple technical improvements could reduce the jitter to better than 50 fs.

  10. Time-resolved spectral analysis of Radachlorin luminescence in water

    NASA Astrophysics Data System (ADS)

    Belik, V. P.; Gadzhiev, I. M.; Semenova, I. V.; Vasyutinskii, O. S.

    2017-05-01

    We report results of spectral- and time-resolved study of Radachlorin photosensitizer luminescence in water in the spectral range of 950-1350nm and for determination of the photosensitizer triplet state and the singlet oxygen lifetimes responsible for singlet oxygen generation and degradation. At any wavelength within the explored spectral range the luminescence decay contained two major contributions: a fast decay at the ns time scale and a slow evolution at the μs time scale. The fast decay was attributed to electric dipole fluorescence transitions in photosensitizer molecules and the slow evolution to intercombination phosphorescence transitions in singlet oxygen and photosensitizer molecules. Relatively high-amplitude ns peak observed at all wavelengths suggests that singlet oxygen monitoring with spectral isolation methods alone, without additional temporal resolution can be controversial. In the applied experimental conditions the total phosphorescence signal at any wavelength contained a contribution from the photosensitizer triplet state decay, while at 1274nm the singlet oxygen phosphorescence dominated. The results obtained can be used for optimization of the methods of singlet oxygen monitoring and imaging.

  11. Time-resolved spectral analysis of Radachlorin luminescence in water.

    PubMed

    Belik, V P; Gadzhiev, I M; Semenova, I V; Vasyutinskii, O S

    2017-05-05

    We report results of spectral- and time-resolved study of Radachlorin photosensitizer luminescence in water in the spectral range of 950-1350nm and for determination of the photosensitizer triplet state and the singlet oxygen lifetimes responsible for singlet oxygen generation and degradation. At any wavelength within the explored spectral range the luminescence decay contained two major contributions: a fast decay at the ns time scale and a slow evolution at the μs time scale. The fast decay was attributed to electric dipole fluorescence transitions in photosensitizer molecules and the slow evolution to intercombination phosphorescence transitions in singlet oxygen and photosensitizer molecules. Relatively high-amplitude ns peak observed at all wavelengths suggests that singlet oxygen monitoring with spectral isolation methods alone, without additional temporal resolution can be controversial. In the applied experimental conditions the total phosphorescence signal at any wavelength contained a contribution from the photosensitizer triplet state decay, while at 1274nm the singlet oxygen phosphorescence dominated. The results obtained can be used for optimization of the methods of singlet oxygen monitoring and imaging. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Time-resolved multiphoton imaging of basal cell carcinoma

    NASA Astrophysics Data System (ADS)

    Cicchi, R.; Sestini, S.; De Giorgi, V.; Stambouli, D.; Carli, P.; Massi, D.; Pavone, F. S.

    2007-02-01

    We investigated human cutaneous basal cell carcinoma ex-vivo samples by combined time resolved two photon intrinsic fluorescence and second harmonic generation microscopy. Morphological and spectroscopic differences were found between malignant skin and corresponding healthy skin tissues. In comparison with normal healthy skin, cancer tissue showed a different morphology and a mean fluorescence lifetime distribution slightly shifted towards higher values. Topical application of delta-aminolevulinic acid to the lesion four hours before excision resulted in an enhancement of the fluorescence signal arising from malignant tissue, due to the accumulation of protoporphyrines inside tumor cells. Contrast enhancement was prevalent at tumor borders by both two photon fluorescence microscopy and fluorescence lifetime imaging. Fluorescence-based images showed a good correlation with conventional histopathological analysis, thereby supporting the diagnostic accuracy of this novel method. Combined morphological and lifetime analysis in the study of ex-vivo skin samples discriminated benign from malignant tissues, thus offering a reliable, non-invasive tool for the in-vivo analysis of inflammatory and neoplastic skin lesions.

  13. Development of ultrafast time-resolved dual-comb spectroscopy

    NASA Astrophysics Data System (ADS)

    Asahara, Akifumi; Minoshima, Kaoru

    2017-04-01

    Ultrafast time-resolved dual-comb spectroscopy (TR-DCS) has been demonstrated, which enables direct observations of transient responses of complex optical spectra by combining dual-comb spectroscopy with the pump-probe method. TR-DCS achieves two-dimensional spectroscopy with a wide dynamic range for both the temporal and frequency axes. As a demonstration, we investigated the femtosecond relaxation dynamics of a photo-excited InGaAs saturable absorber in the near-infrared frequency region. The transient response of the interferogram was successfully obtained, and both the amplitude and phase spectra of the dynamic complex transmittance were independently deduced without using the Kramers-Kronig relations. A high phase resolution in the order of milliradian was achieved by suppressing the effect from the slow phase drift caused in the experimental system. Our proof-of-principle experiment promotes a pathway to coherent, highly accurate, and multi-dimensional pump-probe spectroscopy using the optical frequency comb technology.

  14. Time Resolved Imaging of Longitudinal Modulations in Intense Beams

    NASA Astrophysics Data System (ADS)

    Tian, Kai

    2007-11-01

    The longitudinal evolution of high intensity beams is not well understood despite its importance to the success of such applications as free electron lasers and light sources, heavy ion inertial fusion, and high energy colliders. For example any amplification of current modulations in an FEL photoinjector can lead to unwanted coherent synchrotron radiation further downstream in compression chicanes or bends. A significant factor usually neglected is the coupling to the transverse dynamics which can strongly affect the longitudinal evolution. Previous experiments at the University of Maryland have revealed much about the longitudinal physics of space-charge dominated beams by monitoring the evolution of longitudinal perturbations. For the first time, experimental results are presented here which reveal the effect of longitudinal perturbations on the transverse beam distribution, with the aid of several new diagnostics that capture detailed time-resolved density images. A longitudinal modulation of the particle density is deliberately generated at the source, and its evolution is tracked downstream using a number of diagnostics such as current monitors, high-resolution energy analyzers, as well as the transverse imaging devices. The latter consist of a high-resolution 16-bit gated camera coupled with very fast emitters such as prompt optical transition radiation (OTR) from an alumina screen, or fast Phosphor screens with 3-ns time resolution. Simulations using the particle-in-cell code WARP are applied to cross-check the experimental results. These experiments and especially the comparisons to simulation represent significant progress towards understanding the longitudinal physics of intense beams.

  15. Time-resolved local strain tracking microscopy for cell mechanics

    NASA Astrophysics Data System (ADS)

    Aydin, O.; Aksoy, B.; Akalin, O. B.; Bayraktar, H.; Alaca, B. E.

    2016-02-01

    A uniaxial cell stretching technique to measure time-resolved local substrate strain while simultaneously imaging adherent cells is presented. The experimental setup comprises a uniaxial stretcher platform compatible with inverted microscopy and transparent elastomer samples with embedded fluorescent beads. This integration enables the acquisition of real-time spatiotemporal data, which is then processed using a single-particle tracking algorithm to track the positions of fluorescent beads for the subsequent computation of local strain. The present local strain tracking method is demonstrated using polydimethylsiloxane (PDMS) samples of rectangular and dogbone geometries. The comparison of experimental results and finite element simulations for the two sample geometries illustrates the capability of the present system to accurately quantify local deformation even when the strain distribution is non-uniform over the sample. For a regular dogbone sample, the experimentally obtained value of local strain at the center of the sample is 77%, while the average strain calculated using the applied cross-head displacement is 48%. This observation indicates that considerable errors may arise when cross-head measurement is utilized to estimate strain in the case of non-uniform sample geometry. Finally, the compatibility of the proposed platform with biological samples is tested using a unibody PDMS sample with a well to contain cells and culture media. HeLa S3 cells are plated on collagen-coated samples and cell adhesion and proliferation are observed. Samples with adherent cells are then stretched to demonstrate simultaneous cell imaging and tracking of embedded fluorescent beads.

  16. Time-resolved shadowgraphy of optical breakdown in fused silica

    NASA Astrophysics Data System (ADS)

    Tran, K. A.; Grigorov, Y. V.; Nguyen, V. H.; Rehman, Z. U.; Le, N. T.; Janulewicz, K. A.

    2015-07-01

    Dynamics of a laser-induced optical breakdown in the bulk of fused silica initiated by a sub-nanosecond laser pulse of an energy fluence as high as 8.7 kJ/cm2 was investigated by using femtosecond time-resolved shadowgraphy. Plasma ignition, growth of the damaged region and accompanying hydrodynamic motion were recorded from the moment directly before the arrival of the driving laser pulse, in the time steps adapted to the rate of the occurring processes. The growth rate of the plasma channel, curvature radii and velocities of the wave fronts were extracted from the shadowgrams. It was found that the plasma channel develops with a supersonic velocity and the first observed shock front tends to transform itself from the initial bowl-like shape to the final spherical one characterising an acoustic wave. Appearance of multiple fronts accompanying the main shock front was registered and used in more detailed analysis of the optical breakdown dynamics in the transparent dielectrics.

  17. Time-resolved hard x-ray spectrometer

    NASA Astrophysics Data System (ADS)

    Moy, Kenneth; Cuneo, Michael; McKenna, Ian; Keenan, Thomas; Sanford, Thomas; Mock, Ray

    2006-08-01

    Wired array studies are being conducted at the SNL Z accelerator to maximize the x-ray generation for inertial confinement fusion targets and high energy density physics experiments. An integral component of these studies is the characterization of the time-resolved spectral content of the x-rays. Due to potential spatial anisotropy in the emitted radiation, it is also critical to diagnose the time-evolved spectral content in a space-resolved manner. To accomplish these two measurement goals, we developed an x-ray spectrometer using a set of high-speed detectors (silicon PIN diodes) with a collimated field-of-view that converged on a 1-cm-diameter spot at the pinch axis. Spectral discrimination is achieved by placing high Z absorbers in front of these detectors. We built two spectrometers to permit simultaneous different angular views of the emitted radiation. Spectral data have been acquired from recent Z shots for the radial and axial (polar) views. UNSPEC 1 has been adapted to analyze and unfold the measured data to reconstruct the x-ray spectrum. The unfold operator code, UFO2, is being adapted for a more comprehensive spectral unfolding treatment.

  18. Hydroelectric structures studies using 3-dimensional methods

    SciTech Connect

    Harrell, T.R.; Jones, G.V.; Toner, C.K. )

    1989-01-01

    Deterioration and degradation of aged, hydroelectric project structures can significantly affect the operation and safety of a project. In many cases, hydroelectric headworks (in particular) have complicated geometrical configurations, loading patterns and hence, stress conditions. An accurate study of such structures can be performed using 3-dimensional computer models. 3-D computer models can be used for both stability evaluation and for finite element stress analysis. Computer aided engineering processes facilitate the use of 3-D methods in both pre-processing and post-processing of data. Two actual project examples are used to emphasize the authors' points.

  19. Time resolved studies of bond activation by organometallic complexes

    SciTech Connect

    Wilkens, Matthew J.

    1998-05-01

    In 1971, Jetz and Graham discovered that the silicon-hydrogen bond in silanes could be broken under mild photochemical conditions in the presence of certain transition metal carbonyls. Such reactions fall within the class of oxidative addition. A decade later, similar reactivity was discovered in alkanes. In these cases a C-H bond in non-functionalized alkanes was broken through the oxidative addition of Cp*Ir(H)2L (Cp* = (CH3)5C5, L = PPh3, Ph = C6H5) to form Cp*ML(R)(H) or of Cp*Ir(CO)2 to form Cp*Ir(CO)(R)(H). These discoveries opened an entirely new field of research, one which naturally included mechanistic studies aimed at elucidating the various paths involved in these and related reactions. Much was learned from these experiments but they shared the disadvantage of studying under highly non-standard conditions a system which is of interest largely because of its characteristics under standard conditions. Ultrafast time-resolved IR spectroscopy provides an ideal solution to this problem; because it allows the resolution of chemical events taking place on the femto-through picosecond time scale, it is possible to study this important class of reactions under the ambient conditions which are most of interest to the practicing synthetic chemist. Certain of the molecules in question are particularly well-suited to study using the ultrafast IR spectrophotometer described in the experimental section because they contain one or more carbonyl ligands.

  20. Microsecond Time-Resolved Circular Dichroism of Rhodopsin Photointermediates†

    PubMed Central

    Thomas, Yiren Gu; Szundi, Istvan; Lewis, James W.; Kliger, David S.

    2009-01-01

    Time-resolved circular dichroism measurements, over a spectral range from 300 to 700 nm, were made at delays of 5, 100 and 500 μs after room temperature photoexcitation of bovine rhodopsin in lauryl maltoside suspension. The purpose was to provide more structural information about intermediate states in the activation of rhodopsin and other G protein-coupled receptors. In particular, information was sought about photointermediates that are isochromic or nearly isochromic in their unpolarized absorbance. The circular dichroism spectrum of lumirhodopsin, obtained after correcting the 5 μs difference CD data for the rhodopsin bleached, was in reasonable agreement with the lumirhodopsin CD spectrum obtained previously by thermal trapping at -76°C. Similarly, the metarhodopsin II spectrum obtained at 500 μs delay was also in agreement with the results of previous work on the temperature trapped form of metarhodopsin II. However, the CD of the mixture formed at 100 μs delay after photoexcitation, whose only visible absorbing component is lumirhodopsin, could not be accounted for near 480 nm in terms of the initially formed, 5 μs lumirhodopsin CD spectrum. Thus, the CD spectrum of lumirhodopsin changes on the time scale from 5 to 100 μs, showing reduced rotational strength in its visible band, possibly associated with either a process responsible for a small spectral shift that occurs in the lumirhodopsin absorbance spectrum at earlier times or the Schiff base deprotonation-reprotonation which occurs during equilibration of lumirhodopsin with the Meta I380 photointermediate. Either explanation suggests a chromophore conformation change closely associated with deprotonation which could be the earliest direct trigger of activation. PMID:19905009

  1. Time-resolved study of Higgs mode in superconductors

    NASA Astrophysics Data System (ADS)

    Shimano, Ryo

    The behavior of superconductors far from equilibrium has been intensively studied over decades. Goals of these studies are the elucidation of bosonic fluctuations essential for the pairing mechanisms, the manifestation of competing orders or hidden phases, and the optical manipulation of superconductivity. The study of collective modes is crucially important for these perspectives as it provides the information on the dynamics of order parameters in non-equilibirium states. Generally, collective modes in ordered phases associated with spontaneous symmetry breaking are classified into 1) gapless phase modes and 2) gapped amplitude modes. In superconductors, the phase mode is eaten by gauge field, according to the Anderson-Higgs mechanism. The remaining amplitude mode is recently termed as Higgs mode from its analogy to the Higgs boson in particle physics. Despite its long history of investigation, unambiguous observation of Higgs mode has remained elusive. This is because the Higgs mode does not have a charge nor electric dipole and therefore it does not couple directly to the electromagnetic field. Here we report on our recent observation of Higgs mode in s-wave superconductors by using THz-pump and THz-probe spectroscopy technique. After nonadiabatic excitation near the superconducting gap energy with monocycle THz pulses, Higgs mode was observed as oscillations in the transmission of THz probe pulse. The resonant nonlinear coupling between the Higgs mode and coherent radiation field was also discovered, resulting in an efficient third order harmonic generation of the incident THz radiation. The extension of experiments to multiband superconductors and unconventional superconductors will be discussed. Time-resolved study of Higgs mode in superconductors.

  2. Time-resolved serial crystallography captures high-resolution intermediates of photoactive yellow protein

    SciTech Connect

    Tenboer, Jason; Basu, Shibom; Zatsepin, Nadia; Pande, Kanupriya; Milathianaki, Despina; Frank, Matthias; Hunter, Mark; Boutet, Sebastien; Williams, Garth J.; Koglin, Jason E.; Oberthuer, Dominik; Heymann, Michael; Kupitz, Christopher; Conrad, Chelsie; Coe, Jesse; Roy-Chowdhury, Shatabdi; Weierstall, Uwe; James, Daniel; Wang, Dingjie; Grant, Thomas; Barty, Anton; Yefanov, Oleksandr; Scales, Jennifer; Gati, Cornelius; Seuring, Carolin; Srajer, Vukica; Henning, Robert; Schwander, Peter; Fromme, Raimund; Ourmazd, Abbas; Moffat, Keith; Van Thor, Jasper J.; Spence, John C. H.; Fromme, Petra; Chapman, Henry N.; Schmidt, Marius

    2014-12-05

    We report that serial femtosecond crystallography using ultrashort pulses from X-ray Free Electron Lasers (XFELs) offers the possibility to study light-triggered dynamics of biomolecules. Using microcrystals of the blue light photoreceptor, photoactive yellow protein, as a model system, we present high resolution, time-resolved difference electron density maps of excellent quality with strong features, which allow the determination of structures of reaction intermediates to 1.6 Å resolution. These results open the way to the study of reversible and non-reversible biological reactions on time scales as short as femtoseconds under conditions which maximize the extent of reaction initiation throughout the crystal.

  3. Time-resolved torsional relaxation of spider draglines by an optical technique.

    PubMed

    Emile, O; Le Floch, A; Vollrath, F

    2007-04-20

    The sensitivity of the torsional pendulum demonstrates the self-shape-memory effect in different types of spider draglines. Here we report the time-resolved noncovalent bonds recovery in the protein structure. The torsional dynamics of such multilevel structure governed by reversible interactions are described in the frame of a nested model. Measurement of three different relaxation times confirms the existence of three energy storage levels in such two protein spidroin systems. Torsion opens the way to further investigations towards unraveling the tiny torque effects in biological molecules.

  4. Time-Resolved Torsional Relaxation of Spider Draglines by an Optical Technique

    NASA Astrophysics Data System (ADS)

    Emile, O.; Floch, A. Le; Vollrath, F.

    2007-04-01

    The sensitivity of the torsional pendulum demonstrates the self-shape-memory effect in different types of spider draglines. Here we report the time-resolved noncovalent bonds recovery in the protein structure. The torsional dynamics of such multilevel structure governed by reversible interactions are described in the frame of a nested model. Measurement of three different relaxation times confirms the existence of three energy storage levels in such two protein spidroin systems. Torsion opens the way to further investigations towards unraveling the tiny torque effects in biological molecules.

  5. Optoacoustic tomography using time-resolved interferometric detection of surface displacement.

    PubMed

    Payne, Barry P; Venugopalan, Vasan; Mikić, Bora B; Nishioka, Norman S

    2003-04-01

    We introduce a minimally invasive technique for optoacoustic imaging of turbid media using optical interferometric detection of surface displacement produced by thermoelastic stress transients. The technique exploits endogenous or exogenous optical contrast of heterogeneous tissues and the low attenuation of stress wave propagation to localize and image subsurface absorbers in optically turbid media. We present a system that utilizes a time-resolved high-resolution interferometer capable of angstrom-level displacement resolution and nanosecond temporal resolution to detect subsurface blood vessels within model tissue phantoms and a human forearm in vivo.

  6. Phase effects due to previous pulses in time-resolved Faraday rotation measurements

    SciTech Connect

    Trowbridge, Christopher J.; Sih, Vanessa

    2015-02-14

    Time-resolved Faraday rotation measurements have proved transformative in the investigation of spin dynamics in semiconductors. In materials with spin lifetimes which are on the order of, or greater than, the laser repetition time, the collective effect of spin polarization due to the whole pump pulse train becomes important. Here, we discuss a relative phase shift which results from these spins. We derive and experimentally validate a closed-form expression which describes this phase shift and characterize it throughout parameter space. A spin lifetime measurement based on this phase shift is described, and we discuss situations in which the model used must be augmented to be applicable.

  7. Attosecond time-resolved imaging of molecular structure by photoelectron holography.

    PubMed

    Bian, Xue-Bin; Bandrauk, André D

    2012-06-29

    Dynamic imaging of the molecular structure of H(2)(+) is investigated by attosecond photoelectron holography. The interference between direct (reference) and backward rescattered (signal) photoelectrons in attosecond photoelectron holography reveals the birth time of both channels and the spatial information of molecular structure. This is confirmed by simulations with a semiclassical model and numerical solutions of the corresponding time-dependent Schrödinger equation, suggesting an attosecond time-resolved way of imaging molecular structure obtained from laser induced rescattering of ionized electrons. It is shown that both short and long rescattered electron trajectories can be imaged from the momentum distribution.

  8. Time-Resolved Serial Crystallography Captures High Resolution Intermediates of Photoactive Yellow Protein

    PubMed Central

    Tenboer, Jason; Basu, Shibom; Zatsepin, Nadia; Pande, Kanupria; Milathianaki, Despina; Frank, Matthias; Hunter, Mark; Boutet, Sébastien; Williams, Garth J.; Koglin, Jason E.; Oberthuer, Dominik; Heymann, Michael; Kupitz, Christopher; Conrad, Chelsie; Coe, Jesse; Roy-Chowdhury, Shatabdi; Weierstall, Uwe; James, Daniel; Wang, Dingjie; Grant, Thomas; Barty, Anton; Yefanov, Oleksandr; Scales, Jennifer; Gati, Cornelius; Seuring, Carolin; Srajer, Vukica; Henning, Robert; Schwander, Peter; Fromme, Raimund; Ourmazd, Abbas; Moffat, Keith; Van Thor, Jasper; Spence, John H. C.; Fromme, Petra; Chapman, Henry N.; Schmidt, Marius

    2015-01-01

    Serial femtosecond crystallography using ultrashort pulses from X-ray Free Electron Lasers (XFELs) offers the possibility to study light-triggered dynamics of biomolecules. Using microcrystals of the blue light photoreceptor, photoactive yellow protein, as a model system, we present high resolution, time-resolved difference electron density maps of excellent quality with strong features, which allow the determination of structures of reaction intermediates to 1.6 Å resolution. These results open the way to the study of reversible and non-reversible biological reactions on time scales as short as femtoseconds under conditions which maximize the extent of reaction initiation throughout the crystal. PMID:25477465

  9. Development of time resolved x-ray spectroscopy in high intensity laser-plasma interactions

    SciTech Connect

    Notley, M. M.; Weber, R. L.; Fell, B.; Jeffries, J.; Freeman, R. R.; Mackinnon, A. J.; Dickson, R.; Hey, D.; Khattak, F.; Saiz, E. Garcia; Gregori, G.

    2006-10-15

    This article discusses the design of a novel time resolved von Hamos Bragg spectrometer to provide spectra in the region around the titanium K-{alpha} and He-{alpha} lines. The instrument consists of a highly oriented pyrolitic graphite mosaic crystal coupled to a picosecond x-ray streak camera. Measurements of the time dependent behavior from Ti foils illuminated with intense laser pulses can be used to improve the understanding of recombination dynamics, electron transport, and phase transitions in strongly coupled dense plasma. This is important for the modeling of the compression phase in inertial confinement fusion research and the study of astrophysical environments.

  10. Time-resolved serial crystallography captures high-resolution intermediates of photoactive yellow protein

    DOE PAGES

    Tenboer, Jason; Basu, Shibom; Zatsepin, Nadia; ...

    2014-12-05

    We report that serial femtosecond crystallography using ultrashort pulses from X-ray Free Electron Lasers (XFELs) offers the possibility to study light-triggered dynamics of biomolecules. Using microcrystals of the blue light photoreceptor, photoactive yellow protein, as a model system, we present high resolution, time-resolved difference electron density maps of excellent quality with strong features, which allow the determination of structures of reaction intermediates to 1.6 Å resolution. These results open the way to the study of reversible and non-reversible biological reactions on time scales as short as femtoseconds under conditions which maximize the extent of reaction initiation throughout the crystal.

  11. A thermodynamic and mechanical model for formation of the Solar System via 3-dimensional collapse of the dusty pre-solar nebula

    NASA Astrophysics Data System (ADS)

    Hofmeister, Anne M.; Criss, Robert E.

    2012-03-01

    The fundamental and shared rotational characteristics of the Solar System (nearly circular, co-planar orbits and mostly upright axial spins of the planets) record conditions of origin, yet are not explained by prevailing 2-dimensional disk models. Current planetary spin and orbital rotational energies (R.E.) each nearly equal and linearly depend on gravitational self-potential of formation (Ug), revealing mechanical energy conservation. We derive -ΔUg≅Δ.R.E. and stability criteria from thermodynamic principles, and parlay these relationships into a detailed model of simultaneous accretion of the protoSun and planets from the dust-bearing 3-d pre-solar nebula (PSN). Gravitational heating is insignificant because Ug is negative, the 2nd law of thermodynamics must be fulfilled, and ideal gas conditions pertain to the rarified PSN until the objects were nearly fully formed. Combined conservation of angular momentum and mechanical energy during 3-dimensional collapse of spheroidal dust shells in a contracting nebula provides ΔR.E.≅R.E. for the central body, whereas for formation of orbiting bodies, ΔR.E.≅R.E.f(1-If/Ii), where I is the moment of inertia. Orbital data for the inner planets follow 0.04×R.E.f≅-Ug which confirms conservation of angular momentum. Significant loss of spin, attributed to viscous dissipation during differential rotation, masks the initial spin of the un-ignited protoSun predicted by R.E.=-Ug. Heat production occurs after nearly final sizes are reached via mechanisms such as shear during differential rotation and radioactivity. We focus on the dilute stage, showing that the PSN was compositionally graded due to light molecules diffusing preferentially, providing the observed planetary chemistry, and set limits on PSN mass, density, and temperature. From measured planetary masses and orbital characteristics, accounting for dissipation of spin, we deduce mechanisms and the sequence of converting a 3-d dusty cloud to the present 2-d

  12. Advanced Time-Resolved Fluorescence Microscopy Techniques for the Investigation of Peptide Self-Assembly

    NASA Astrophysics Data System (ADS)

    Anthony, Neil R.

    The ubiquitous cross beta sheet peptide motif is implicated in numerous neurodegenerative diseases while at the same time offers remarkable potential for constructing isomorphic high-performance bionanomaterials. Despite an emerging understanding of the complex folding landscape of cross beta structures in determining disease etiology and final structure, we lack knowledge of the critical initial stages of nucleation and growth. In this dissertation, I advance our understanding of these key stages in the cross-beta nucleation and growth pathways using cutting-edge microscopy techniques. In addition, I present a new combined time-resolved fluorescence analysis technique with the potential to advance our current understanding of subtle molecular level interactions that play a pivotal role in peptide self-assembly. Using the central nucleating core of Alzheimer's Amyloid-beta protein, Abeta(16 22), as a model system, utilizing electron, time-resolved, and non-linear microscopy, I capture the initial and transient nucleation stages of peptide assembly into the cross beta motif. In addition, I have characterized the nucleation pathway, from monomer to paracrystalline nanotubes in terms of morphology and fluorescence lifetime, corroborating the predicted desolvation process that occurs prior to cross-beta nucleation. Concurrently, I have identified unique heterogeneous cross beta domains contained within individual nanotube structures, which have potential bionanomaterials applications. Finally, I describe a combined fluorescence theory and analysis technique that dramatically increases the sensitivity of current time-resolved techniques. Together these studies demonstrate the potential for advanced microscopy techniques in the identification and characterization of the cross-beta folding pathway, which will further our understanding of both amyloidogenesis and bionanomaterials.

  13. Time-resolved three-dimensional pulmonary MR angiography and perfusion imaging with ultrashort repetition time.

    PubMed

    Carr, James C; Laub, Gerhard; Zheng, Jie; Pereles, F Scott; Finn, J Paul

    2002-12-01

    The purpose of this study was to implement ultrafast, multiphase three-dimensional (3D) magnetic resonance (MR) angiography and perfusion imaging after bolus injection of contrast medium to generate preliminary validation of parameters in a pig model and to illustrate potential applications in patients with lung abnormalities. Five healthy volunteers, five patients, and three pigs underwent rapid, time-resolved pulmonary MR angiography and perfusion imaging on a 1.5-T MR imager. All patients had undergone correlative computed tomographic or conventional angiography. The pulse sequence was a 3D spin-warp, gradient-echo acquisition with a repetition time of 1.6 msec and an echo time of 0.6 msec. Each 3D acquisition lasted 2-3 seconds, and 8-16 sequential measurements were made in each study. Artificial pulmonary emboli were generated in pigs with gelatin sponge. All patients had diseases of the pulmonary circulation (as confirmed with other studies). Multiphasic, time-resolved pulmonary parenchymal enhancement was demonstrated in all healthy subjects and animals. All segmental (n = 100) and subsegmental (n = 200) branches were identified in the healthy subjects. Perfusion deficits were clearly demonstrated in all pigs after gelatin embolization. Perfusion defects were identified in two patients with lung disease. Abnormalities of the pulmonary vasculature were clearly identified in the patient group. Dynamic time-resolved 3D pulmonary MR angiography and perfusion imaging is feasible in humans as well as in animals. Induced perfusion deficits are identifiable after artificial embolization in pigs. Combined pulmonary MR angiography and parenchymal (perfusion) imaging may improve evaluation of the pulmonary circulation in a variety of conditions.

  14. Hemoglobin oxygenation of a two-layer tissue-simulating phantom from time-resolved reflectance

    NASA Astrophysics Data System (ADS)

    Hunter, Robert John

    2002-04-01

    A dual wavelength time-resolved reflectance system was developed for monitoring hemoglobin saturation noninvasively. The ability of the system to determine the optical properties of tissue-simulating phantoms was examined. To quantify the accuracy of the technique in monitoring hemoglobin saturation, measurements were performed in a homogeneous phantom containing human erythrocytes in a scattering solution. The hemoglobin saturation of this phantom could be controlled and monitored with an alternate technique. After system validation in this simple model, a more realistic, two-layer phantom model was investigated. The top layer was chosen to simulate either skin or fat and the oxygenation of the bottom layer, which corresponded to muscle, was controlled. The thickness of the fat layer was varied from 1.5 to 10 mm to investigate the effects of increasing the top layer thickness. Time-resolved measurements of reflectance, performed through the top layer were analyzed with a simple homogeneous diffusion model to quantify the hemoglobin saturation of the bottom layer. These data were compared with simultaneous measurements of oxygenation made directly in the bottom layer. Errors in estimating hemoglobin saturation with this method ranged from 5--11% depending on top layer thickness. Preliminary in vivo measurements were also undertaken which demonstrated promising results, although no comparative technique was used in these studies.

  15. Time-Resolved Spectroscopy of Active Binary Stars

    NASA Technical Reports Server (NTRS)

    Brown, Alexander

    2000-01-01

    This NASA grant covered EUVE observing and data analysis programs during EUVE Cycle 5 GO observing. The research involved a single Guest Observer project 97-EUVE-061 "Time-Resolved Spectroscopy of Active Binary Stars". The grant provided funding that covered 1.25 months of the PI's salary. The activities undertaken included observation planning and data analysis (both temporal and spectral). This project was awarded 910 ksec of observing time to study seven active binary stars, all but one of which were actually observed. Lambda-And was observed on 1997 Jul 30 - Aug 3 and Aug 7-14 for a total of 297 ksec; these observations showed two large complex flares that were analyzed by Osten & Brown (1999). AR Psc, observed for 350 ksec on 1997 Aug 27 - Sep 13, showed only relatively small flares that were also discussed by Osten & Brown (1999). EUVE observations of El Eri were obtained on 1994 August 24-28, simultaneous with ASCA X-ray spectra. Four flares were detected by EUVE with one of these also observed simultaneously, by ASCA. The other three EUVE observations were of the stars BY Dra (1997 Sep 22-28), V478 Lyr (1998 May 18-27), and sigma Gem (1998 Dec 10-22). The first two stars showed a few small flares. The sigma Gem data shows a beautiful complete flare with a factor of ten peak brightness compared to quiescence. The flare rise and almost all the decay phase are observed. Unfortunately no observations in other spectral regions were obtained for these stars. Analysis of the lambda-And and AR Psc observations is complete and the results were published in Osten & Brown (1999). Analysis of the BY Dra, V478 Lyr and sigma Gem EUVE data is complete and will be published in Osten (2000, in prep.). The El Eri EUV analysis is also completed and the simultaneous EUV/X-ray study will be published in Osten et al. (2000, in prep.). Both these latter papers will be submitted in summer 2000. All these results will form part of Rachel Osten's PhD thesis.

  16. Time-resolved neutron scattering provides new insight into protein substrate processing by a AAA+ unfoldase

    PubMed Central

    Ibrahim, Ziad; Martel, Anne; Moulin, Martine; Kim, Henry S.; Härtlein, Michael; Franzetti, Bruno; Gabel, Frank

    2017-01-01

    We present a combination of small-angle neutron scattering, deuterium labelling and contrast variation, temperature activation and fluorescence spectroscopy as a novel approach to obtain time-resolved, structural data individually from macromolecular complexes and their substrates during active biochemical reactions. The approach allowed us to monitor the mechanical unfolding of a green fluorescent protein model substrate by the archaeal AAA+ PAN unfoldase on the sub-minute time scale. Concomitant with the unfolding of its substrate, the PAN complex underwent an energy-dependent transition from a relaxed to a contracted conformation, followed by a slower expansion to its initial state at the end of the reaction. The results support a model in which AAA ATPases unfold their substrates in a reversible power stroke mechanism involving several subunits and demonstrate the general utility of this time-resolved approach for studying the structural molecular kinetics of multiple protein remodelling complexes and their substrates on the sub-minute time scale. PMID:28102317

  17. Use of time-resolved fluorescence spectroscopy to evaluate diagnostic value of collagen degradation products.

    PubMed

    Sikora, Joanna; Cyrankiewicz, Michał; Wybranowski, Tomasz; Ziomkowska, Blanka; Ośmiałowski, Borys; Obońska, Ewa; Augustyńska, Beata; Kruszewski, Stefan; Kubica, Jacek

    2015-05-01

    The concentration of collagen degradation products (CDPs) may reflect the process of left ventricular remodeling (LVR). The aim of this study was to evaluate the potential diagnostic usefulness of time-resolved fluorescence spectroscopy (TRFS) in assessment of CDPs. The preliminary experiment was designed to establish if CDPs’ characteristics might be visible by mean fluorescence lifetime (FLT) in determined conditions. The in vitro model of CDPs was prepared by conducting the hydrolysis of type III collagen. The FLT of samples was measured by the time-resolved spectrometer Life Spec II with the subnanosecond pulsed 360-nm EPLED diode. The FLTs were obtained by deconvolution analysis of the data using a multiexponential model of fluorescence decay. In order to determine the limit of traceability of CDPs, a comparison of different collagen/plasma ratio in samples was performed. The results of our study showed that the increase of added plasma to hydrolyzed collagen extended the mean FLT. Thus, the diagnosis of LVR based on measurements using TRFS is possible. However, it is important to point out the experiment was preliminary and further investigation in this field of research is crucial.

  18. Time resolved dosimetry of human brain exposed to low frequency pulsed magnetic fields

    NASA Astrophysics Data System (ADS)

    Paffi, Alessandra; Camera, Francesca; Lucano, Elena; Apollonio, Francesca; Liberti, Micaela

    2016-06-01

    An accurate dosimetry is a key issue to understanding brain stimulation and related interaction mechanisms with neuronal tissues at the basis of the increasing amount of literature revealing the effects on human brain induced by low-level, low frequency pulsed magnetic fields (PMFs). Most literature on brain dosimetry estimates the maximum E field value reached inside the tissue without considering its time pattern or tissue dispersivity. Nevertheless a time-resolved dosimetry, accounting for dispersive tissues behavior, becomes necessary considering that the threshold for an effect onset may vary depending on the pulse waveform and that tissues may filter the applied stimulatory fields altering the predicted stimulatory waveform’s size and shape. In this paper a time-resolved dosimetry has been applied on a realistic brain model exposed to the signal presented in Capone et al (2009 J. Neural Transm. 116 257-65), accounting for the broadband dispersivity of brain tissues up to several kHz, to accurately reconstruct electric field and current density waveforms inside different brain tissues. The results obtained by exposing the Duke’s brain model to this PMF signal show that the E peak in the brain is considerably underestimated if a simple monochromatic dosimetry is carried out at the pulse repetition frequency of 75 Hz.

  19. Space and time-resolved probing of heterogeneous catalysis reactions using lab-on-a-chip

    NASA Astrophysics Data System (ADS)

    Navin, Chelliah V.; Krishna, Katla Sai; Theegala, Chandra S.; Kumar, Challa S. S. R.

    2016-03-01

    Probing catalytic reactions on a catalyst surface in real time is a major challenge. Herein, we demonstrate the utility of a continuous flow millifluidic chip reactor coated with a nanostructured gold catalyst as an effective platform for in situ investigation of the kinetics of catalytic reactions by taking 5-(hydroxymethyl)furfural (HMF) to 2,5-furandicarboxylic acid (FDCA) conversion as a model reaction. The idea conceptualized in this paper can not only dramatically change the ability to probe the time-resolved kinetics of heterogeneous catalysis reactions but also used for investigating other chemical and biological catalytic processes, thereby making this a broad platform for probing reactions as they occur within continuous flow reactors.Probing catalytic reactions on a catalyst surface in real time is a major challenge. Herein, we demonstrate the utility of a continuous flow millifluidic chip reactor coated with a nanostructured gold catalyst as an effective platform for in situ investigation of the kinetics of catalytic reactions by taking 5-(hydroxymethyl)furfural (HMF) to 2,5-furandicarboxylic acid (FDCA) conversion as a model reaction. The idea conceptualized in this paper can not only dramatically change the ability to probe the time-resolved kinetics of heterogeneous catalysis reactions but also used for investigating other chemical and biological catalytic processes, thereby making this a broad platform for probing reactions as they occur within continuous flow reactors. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06752a

  20. Time-resolved photoemission spectroscopy on a metal/ferroelectric heterostructure

    NASA Astrophysics Data System (ADS)

    Rault, J. E.; Agnus, G.; Maroutian, T.; Pillard, V.; Lecoeur, Ph.; Niu, G.; Vilquin, B.; Silly, M. G.; Bendounan, A.; Sirotti, F.; Barrett, N.

    2013-10-01

    In thin-film ferroelectric (FE) capacitors the chemical and electronic structure of the electrode/FE interface can play a crucial role in determining the kinetics of polarization switching. We investigate the electronic structure of a Pt/BaTiO3/SrTiO3:Nb capacitor using time-resolved photoemission spectroscopy. The chemical, electronic, and depth sensitivity of core-level photoemission are used to probe the transient response of different parts of the upper electrode/ferroelectric interface to voltage-pulse-induced polarization reversal. The linear response of the electronic structure agrees quantitatively with a simple RC circuit model. The nonlinear response due to the polarization switch is demonstrated by the time-resolved response of the characteristic core levels of the electrode and the ferroelectric. Adjustment of the RC circuit model allows an estimation of the Pt/BaTiO3 (BTO) interface capacitance. The experiment shows that the interface capacitance is at least 100 times higher than the bulk capacitance of the BTO film, in qualitative agreement with theoretical predictions from the literature.

  1. Feasibility analysis of an epidermal glucose sensor based on time-resolved fluorescence

    NASA Astrophysics Data System (ADS)

    Katika, Kamal M.; Pilon, Laurent

    2007-06-01

    The goal of this study is to test the feasibility of using an embedded time-resolved fluorescence sensor for monitoring glucose concentration. Skin is modeled as a multilayer medium with each layer having its own optical properties and fluorophore absorption coefficients, lifetimes, and quantum yields obtained from the literature. It is assumed that the two main fluorophores contributing to the fluorescence at these excitation and emission wavelengths are nicotinamide adenine dinucleotide (NAD)H and collagen. The intensity distributions of excitation and fluorescent light in skin are determined by solving the transient radiative transfer equation by using the modified method of characteristics. The fluorophore lifetimes are then recovered from the simulated fluorescence decays and compared with the actual lifetimes used in the simulations. Furthermore, the effect of adding Poissonian noise to the simulated decays on recovering the lifetimes was studied. For all cases, it was found that the fluorescence lifetime of NADH could not be recovered because of its negligible contribution to the overall fluorescence signal. The other lifetimes could be recovered to within 1.3% of input values. Finally, the glucose concentrations within the skin were recovered to within 13.5% of their actual values, indicating a possibility of measuring glucose concentrations by using a time-resolved fluorescence sensor.

  2. Time-Resolved In Situ Measurements During Rapid Alloy Solidification: Experimental Insight for Additive Manufacturing

    DOE PAGES

    McKeown, Joseph T.; Zweiacker, Kai; Liu, Can; ...

    2016-01-27

    In research and industrial environments, additive manufacturing (AM) of metals and alloys is becoming a pervasive technology, though significant challenges remain before widespread implementation of AM can be realized. In situ investigations of rapid alloy solidification with high spatial and temporal resolutions can provide unique experimental insight into microstructure evolution and kinetics that are relevant for AM processing. Hypoeutectic thin-film Al–Cu and Al–Si alloys were investigated using dynamic transmission electron microscopy to monitor pulsed-laser-induced rapid solidification across microsecond timescales. Solid–liquid interface velocities measured from time-resolved images revealed accelerating solidification fronts in both alloys. We observed microstructure evolution, solidification product, andmore » presence of a morphological instability at the solid–liquid interface in the Al–4 at.%Cu alloy are related to the measured interface velocities and small differences in composition that affect the thermophysical properties of the alloys. These time-resolved in situ measurements can inform and validate predictive modeling efforts for AM.« less

  3. Femtosecond laser ablation dynamics of fused silica extracted from oscillation of time-resolved reflectivity

    SciTech Connect

    Kumada, Takayuki Akagi, Hiroshi; Itakura, Ryuji; Otobe, Tomohito; Yokoyama, Atsushi

    2014-03-14

    Femtosecond laser ablation dynamics of fused silica is examined via time-resolved reflectivity measurements. After optical breakdown was caused by irradiation of a pump pulse with fluence F{sub pump} = 3.3–14.9 J/cm{sup 2}, the reflectivity oscillated with a period of 63 ± 2 ps for a wavelength λ = 795 nm. The period was reduced by half for λ = 398 nm. We ascribe the oscillation to the interference between the probe pulses reflected from the front and rear surfaces of the photo-excited molten fused silica layer. The time-resolved reflectivity agrees closely with a model comprising a photo-excited layer which expands due to the formation of voids, and then separates into two parts, one of which is left on the sample surface and the other separated as a molten thin layer from the surface by the spallation mechanism. Such oscillations were not observed in the reflectivity of soda-lime glass. Whether the reflectivity oscillates or not probably depends on the layer viscosity while in a molten state. Since viscosity of the molten fused silica is several orders of magnitude higher than that of the soda-lime glass at the same temperature, fused silica forms a molten thin layer that reflects the probe pulse, whereas the soda-lime glass is fragmented into clusters.

  4. A low-cost time-resolved spot diagnostic for flash x-ray machines

    NASA Astrophysics Data System (ADS)

    Howorth, J.; Ingle, Martin B.; Simpson, Peter; Aedy, Christopher; Quillin, Stephen

    2005-03-01

    AWE has embarked on a programme to develop an improved intense electron beam diode for flash x-ray radiography machines. In order to understand the performance of the diode and to validate computer modelling codes, there is a requirement to obtain time resolved x-ray spot size and position data during the 50 ns electron beam pulse. A simple, low cost, time resolved spot diagnostic has been designed in collaboration with Photek Limited. The system is based around number of identical, single frame, fast gating intensified CCD camera modules viewing a very fast organic scintillator. Each camera has an independent internal delay generator and a microchannel plate intensifier (MCP) capable of gate widths down to 1 ns. The complete system is battery driven and controlled remotely via optical fibres to provide electrical isolation and reduce Electro Magnetic Interference (EMI) susceptibility. An initial four frame system (easily extendable to 8 frames and beyond) has been developed and deployed successfully on one of AWE"s flash x-ray machines.

  5. Eight-channel time-resolved tissue oximeter for functional muscle studies

    NASA Astrophysics Data System (ADS)

    Cubeddu, Rinaldo; Biscotti, Giovanni; Pifferi, Antonio; Taroni, Paola; Torricelli, Alessandro; Ferrari, Marco; Quaresima, Valentina

    2003-07-01

    A portable instrument for tissue oximetry based on time-resolved reflectance spectroscopy was developed. The output pulses of 2 laser diodes (683 and 785 nm, 80 MHz pulse repetition rate, 1 mW average power, 100 ps FWHM) are delayed and coupled into a multimode graded-index fiber (50/125 μm and injected into the tissue. The reflectance photons are collected by 8 independent 1 mm fibers and detected by a 16-anode photomultiplier. A time-correlated single photon counting PC board is used for the parallel acquisition of the curves. Simultaneous estimate of the transport scattering and absorption coefficients is achieved by best fitting of time-resolved reflectance curves with a standard model of Diffusion Theory. The performances of the system were tested on phantoms in terms of stability, reproducibility among channels, and accuracy in the determination of the optical properties. Preliminary in vivo measurements were performed on healthy volunteers to monitor spatial changes in calf (medical and lateral gastrocnemius) oxygen hemoglobin saturation and blood volume during dynamic plantar flexion exercise.

  6. Digital image correlation for full-field time-resolved assessment of arterial stiffness

    NASA Astrophysics Data System (ADS)

    Campo, Adriaan; Soons, Joris; Heuten, Hilde; Ennekens, Guy; Goovaerts, Inge; Vrints, Christiaan; Lava, Pascal; Dirckx, Joris

    2014-01-01

    Pulse wave velocity (PWV) of the arterial system is a very important parameter to evaluate cardiovascular health. Currently, however, there is no golden standard for PWV measurement. Digital image correlation (DIC) was used for full-field time-resolved assessment of displacement, velocity, acceleration, and strains of the skin in the neck directly above the common carotid artery. By assessing these parameters, propagation of the pulse wave could be tracked, leading to a new method for PWV detection based on DIC. The method was tested on five healthy subjects. As a means of validation, PWV was measured with ultrasound (US) as well. Measured PWV values were between 3.68 and 5.19 m/s as measured with DIC and between 5.14 and 6.58 m/s as measured with US, with a maximum absolute difference of 2.78 m/s between the two methods. DIC measurements of the neck region can serve as a test base for determining a robust strategy for PWV detection, they can serve as reference for three-dimensional fluid-structure interaction models, or they may even evolve into a screening method of their own. Moreover, full-field, time-resolved DIC can be adapted for other applications in biomechanics.

  7. Time-resolved Optical Spectroscopy of the Cataclysmic Variable PG 0859+415

    NASA Astrophysics Data System (ADS)

    Hoard, D. W.; Szkody, Paula

    1996-10-01

    We present time-resolved, high-resolution (2 Å) spectra of the nova-like cataclysmic variable (CV) PG 0859+415. The average optical spectrum of this star displays a continuum slope that is steeper than expected for a steady state accretion disk this is attributed to the presence of a hot spot with T ˜ 12,000 K at the impact site of the accretion stream. As first observed by Grauer et al., the time- resolved spectra exhibit a transient central absorption feature in the Balmer lines that appears near φ = 0.6 and lasts into the (partial) eclipse, and the radial velocity solution of the Balmer lines shows a phase offset of Δφ = -0.1 from the photometric phasing. System parameters are estimated from the radial velocity solution to the He II lines (which is consistent with an origin close to the white dwarf primary star). Doppler tomograms constructed from the Balmer emission lines reveal the presence of a region of enhanced emission at a location consistent with the expected impact site of the accretion stream with the edge of the disk. Finally, the similarities between PG 0859+415 and the recently identified SW Sextantis subclass of CV is discussed, and a qualitative model for the system is proposed to explain the observational results.

  8. Time-Resolved In Situ Measurements During Rapid Alloy Solidification: Experimental Insight for Additive Manufacturing

    SciTech Connect

    McKeown, Joseph T.; Zweiacker, Kai; Liu, Can; Coughlin, Daniel R.; Clarke, Amy J.; Baldwin, J. Kevin; Gibbs, John W.; Roehling, John D.; Imhoff, Seth D.; Gibbs, Paul J.; Tourret, Damien; Wiezorek, Jörg M. K.; Campbell, Geoffrey H.

    2016-01-27

    In research and industrial environments, additive manufacturing (AM) of metals and alloys is becoming a pervasive technology, though significant challenges remain before widespread implementation of AM can be realized. In situ investigations of rapid alloy solidification with high spatial and temporal resolutions can provide unique experimental insight into microstructure evolution and kinetics that are relevant for AM processing. Hypoeutectic thin-film Al–Cu and Al–Si alloys were investigated using dynamic transmission electron microscopy to monitor pulsed-laser-induced rapid solidification across microsecond timescales. Solid–liquid interface velocities measured from time-resolved images revealed accelerating solidification fronts in both alloys. We observed microstructure evolution, solidification product, and presence of a morphological instability at the solid–liquid interface in the Al–4 at.%Cu alloy are related to the measured interface velocities and small differences in composition that affect the thermophysical properties of the alloys. These time-resolved in situ measurements can inform and validate predictive modeling efforts for AM.

  9. Time-Resolved In Situ Measurements During Rapid Alloy Solidification: Experimental Insight for Additive Manufacturing

    NASA Astrophysics Data System (ADS)

    McKeown, Joseph T.; Zweiacker, Kai; Liu, Can; Coughlin, Daniel R.; Clarke, Amy J.; Baldwin, J. Kevin; Gibbs, John W.; Roehling, John D.; Imhoff, Seth D.; Gibbs, Paul J.; Tourret, Damien; Wiezorek, Jörg M. K.; Campbell, Geoffrey H.

    2016-03-01

    Additive manufacturing (AM) of metals and alloys is becoming a pervasive technology in both research and industrial environments, though significant challenges remain before widespread implementation of AM can be realized. In situ investigations of rapid alloy solidification with high spatial and temporal resolutions can provide unique experimental insight into microstructure evolution and kinetics that are relevant for AM processing. Hypoeutectic thin-film Al-Cu and Al-Si alloys were investigated using dynamic transmission electron microscopy to monitor pulsed-laser-induced rapid solidification across microsecond timescales. Solid-liquid interface velocities measured from time-resolved images revealed accelerating solidification fronts in both alloys. The observed microstructure evolution, solidification product, and presence of a morphological instability at the solid-liquid interface in the Al-4 at.%Cu alloy are related to the measured interface velocities and small differences in composition that affect the thermophysical properties of the alloys. These time-resolved in situ measurements can inform and validate predictive modeling efforts for AM.

  10. Time-Resolved Photoemission of Correlated Electrons Driven Out of Equilibrium

    SciTech Connect

    Moritz, B.; Devereaux, T.P.; Freericks, J.K.; /Georgetown U.

    2010-02-15

    We describe the temporal evolution of the time-resolved photoemission response of the spinless Falicov-Kimball model driven out of equilibrium by strong, applied fields. The model is one of the few possessing a metal-insulator transition and admitting an exact solution in the time domain. The nonequilibrium dynamics, evaluated using an extension of dynamical mean-field theory, show how the driven system differs from two common viewpoints - a quasi-equilibrium system at an elevated, effective temperature (the 'hot' electron model) or a rapid interaction quench ('melting' of the Mott gap) - due to the rearrangement of electronic states and redistribution of spectral weight. The results demonstrate the inherent trade-off between energy and time resolution accompanying the finite width probe-pulses, characteristic of those employed in pump-probe, time-domain experiments, which can be used to focus attention on different aspects of the dynamics near the transition.

  11. Cooperative macromolecular device revealed by meta-analysis of static and time-resolved structures

    SciTech Connect

    Ren, Zhong; Šrajer, Vukica; Knapp, James E.; Royer, Jr., William E.

    2013-04-08

    Here we present a meta-analysis of a large collection of static structures of a protein in the Protein Data Bank in order to extract the progression of structural events during protein function. We apply this strategy to the homodimeric hemoglobin HbI from Scapharca inaequivalvis. We derive a simple dynamic model describing how binding of the first ligand in one of the two chemically identical subunits facilitates a second binding event in the other partner subunit. The results of our ultrafast time-resolved crystallographic studies support this model. We demonstrate that HbI functions like a homodimeric mechanical device, such as pliers or scissors. Ligand-induced motion originating in one subunit is transmitted to the other via conserved pivot points, where the E and F' helices from two partner subunits are 'bolted' together to form a stable dimer interface permitting slight relative rotation but preventing sliding.

  12. Turbulent Statistics from Time-Resolved PIV Measurements of a Jet Using Empirical Mode Decomposition

    NASA Technical Reports Server (NTRS)

    Dahl, Milo D.

    2012-01-01

    Empirical mode decomposition is an adaptive signal processing method that when applied to a broadband signal, such as that generated by turbulence, acts as a set of band-pass filters. This process was applied to data from time-resolved, particle image velocimetry measurements of subsonic jets prior to computing the second-order, two-point, space-time correlations from which turbulent phase velocities and length and time scales could be determined. The application of this method to large sets of simultaneous time histories is new. In this initial study, the results are relevant to acoustic analogy source models for jet noise prediction. The high frequency portion of the results could provide the turbulent values for subgrid scale models for noise that is missed in large-eddy simulations. The results are also used to infer that the cross-correlations between different components of the decomposed signals at two points in space, neglected in this initial study, are important.

  13. Turbulent Statistics From Time-Resolved PIV Measurements of a Jet Using Empirical Mode Decomposition

    NASA Technical Reports Server (NTRS)

    Dahl, Milo D.

    2013-01-01

    Empirical mode decomposition is an adaptive signal processing method that when applied to a broadband signal, such as that generated by turbulence, acts as a set of band-pass filters. This process was applied to data from time-resolved, particle image velocimetry measurements of subsonic jets prior to computing the second-order, two-point, space-time correlations from which turbulent phase velocities and length and time scales could be determined. The application of this method to large sets of simultaneous time histories is new. In this initial study, the results are relevant to acoustic analogy source models for jet noise prediction. The high frequency portion of the results could provide the turbulent values for subgrid scale models for noise that is missed in large-eddy simulations. The results are also used to infer that the cross-correlations between different components of the decomposed signals at two points in space, neglected in this initial study, are important.

  14. Time-resolved pump-probe signals of a continuously driven quantum dot affected by phonons

    NASA Astrophysics Data System (ADS)

    Reiter, D. E.

    2017-03-01

    The interaction of a light field with a quantum-mechanical system can be studied in an optically controlled semiconductor quantum dot. When driven by a continuous light field switched on instantaneously, the quantum dot occupation performs Rabi oscillations. Unlike an atomic system, the quantum dot is coupled to phonons, which leads to a damping of the Rabi oscillations. Here we model the time-resolved probe spectra to monitor these dynamics and study the influence of phonons on the spectra. The spectra consist of up to three peaks, similar to the Mollow triplet known from quantum optics. We develop analytical equations within a rate equation model and show that they agree excellently with a numerical solution using a well established correlation expansion approach.

  15. Recombination at high carrier density in methylammonium lead iodide studied using time-resolved microwave conductivity

    NASA Astrophysics Data System (ADS)

    Labram, John G.; Chabinyc, Michael L.

    2017-08-01

    Time-resolved microwave conductivity (TRMC) is a highly versatile method to rapidly evaluate the electronic properties of semiconducting compounds without the need to construct and optimize electronic devices. In this report, we study how bimolecular and Auger recombination mechanisms affect TRMC measurements. In particular, we investigate how recombination reduces the measured value of the TRMC figure-of-merit: ϕΣμ, at a high incident optical fluence. Using a numerical model, we calculate how these higher-order recombination processes reduce experimentally measured values of ϕΣμ relative to a regime of low carrier concentration with little recombination. By fitting this model to experimentally obtained data for the hybrid halide perovskite compound, methylammonium lead iodide, we are able to extract the bimolecular and Auger rate constants and provide a clear determination of the sum of the hole and electron mobilities for these films.

  16. Structure and function of proteins investigated by crystallographic and spectroscopic time-resolved methods

    NASA Astrophysics Data System (ADS)

    Purwar, Namrta

    Biomolecules play an essential role in performing the necessary functions for life. The goal of this thesis is to contribute to an understanding of how biological systems work on the molecular level. We used two biological systems, beef liver catalase (BLC) and photoactive yellow protein (PYP). BLC is a metalloprotein that protects living cells from the harmful effects of reactive oxygen species by converting H2O2 into water and oxygen. By binding nitric oxide (NO) to the catalase, a complex was generated that mimics the Cat-H2O2 adduct, a crucial intermediate in the reaction promoted by the catalase. The Cat-NO complex is obtained by using a convenient NO generator (1-(N,N-diethylamino)diazen-1-ium-1,2-diolate). Concentrations up to 100˜200 mM are reached by using a specially designed glass cavity. With this glass apparatus and DEANO, sufficient NO occupation is achieved and structure determination of the catalase with NO bound to the heme iron becomes possible. Structural changes upon NO binding are minute. NO has a slightly bent geometry with respect to the heme normal, which results in a substantial overlap of the NO orbitals with the iron-porphyrin molecular orbitals. From the structure of the iron-NO complex, conclusions on the electronic properties of the heme iron can be drawn that ultimately lead to an insight into the catalytic properties of this enzyme. Enzyme kinetics is affected by additional parameters such as temperature and pH. Additionally, in crystallography, the absorbed X-ray dose may impair protein function. To address the effect of these parameters, we performed time-resolved crystallographic experiments on a model system, PYP. By collecting multiple time-series on PYP at increasing X-ray dose levels, we determined a kinetic dose limit up to which kinetically meaningful X-ray data sets can be collected. From this, we conclude that comprehensive time-series spanning up to 12 orders of magnitude in time can be collected from a single PYP

  17. Thin film growth studies using time-resolved x-ray scattering

    NASA Astrophysics Data System (ADS)

    Kowarik, Stefan

    2017-02-01

    Thin-film growth is important for novel functional materials and new generations of devices. The non-equilibrium growth physics involved is very challenging, because the energy landscape for atomic scale processes is determined by many parameters, such as the diffusion and Ehrlich-Schwoebel barriers. We review the in situ real-time techniques of x-ray diffraction (XRD), x-ray growth oscillations and diffuse x-ray scattering (GISAXS) for the determination of structure and morphology on length scales from Å to µm. We give examples of time resolved growth experiments mainly from molecular thin film growth, but also highlight growth of inorganic materials using molecular beam epitaxy (MBE) and electrochemical deposition from liquids. We discuss how scaling parameters of rate equation models and fundamental energy barriers in kinetic Monte Carlo methods can be determined from fits of the real-time x-ray data.

  18. Time-resolved temperature measurement and numerical simulation of millisecond laser irradiated silicon

    SciTech Connect

    Li Zewen; Zhang Hongchao; Shen Zhonghua; Ni Xiaowu

    2013-07-21

    Thermal process of 1064 nm millisecond pulsed Nd:YAG laser irradiated silicon was time-resolved temperature measured by an infrared radiation pyrometer, temperature evolutions of the spot center for wide range of laser energy densities were presented. The waveforms of temperature evolution curves contained much information about phase change, melting, solidification and vaporization. An axisymmetric numerical model was established for millisecond laser heating silicon. The transient temperature fields were obtained by using the finite element method. The numerical results of temperature evolutions of the spot center are in good agreement with the experimental results. Furthermore, the axial temperature distributions of the numerical results give a better understanding of the waveforms in the experimental results. The melting threshold, vaporizing threshold, melting duration, and melting depth were better identified by analyzing two kinds of results.

  19. Space and time-resolved probing of heterogeneous catalysis reactions using lab-on-a-chip.

    PubMed

    Navin, Chelliah V; Krishna, Katla Sai; Theegala, Chandra S; Kumar, Challa S S R

    2016-03-14

    Probing catalytic reactions on a catalyst surface in real time is a major challenge. Herein, we demonstrate the utility of a continuous flow millifluidic chip reactor coated with a nanostructured gold catalyst as an effective platform for in situ investigation of the kinetics of catalytic reactions by taking 5-(hydroxymethyl)furfural (HMF) to 2,5-furandicarboxylic acid (FDCA) conversion as a model reaction. The idea conceptualized in this paper can not only dramatically change the ability to probe the time-resolved kinetics of heterogeneous catalysis reactions but also used for investigating other chemical and biological catalytic processes, thereby making this a broad platform for probing reactions as they occur within continuous flow reactors.

  20. Attosecond time-resolved streaked photoelectron spectroscopy of transition-metal nanospheres

    NASA Astrophysics Data System (ADS)

    Li, Jianxiong; Saydanzad, Erfan; Thumm, Uwe

    2017-04-01

    Streaked photoemission from nanostructured surfaces and nanoparticles by attosecond extreme ultraviolet pulses into an infrared (IR) or visible streaking pulse allows for sub-fs-resolution of the plasmonically enhanced streaking-pulse electric field. It thus holds promise for the time-resolved imaging of the dielectric response in and plasmonic fields near nanostructures. After calculating the plasmonic field induced by IR and visible streaking pulses in 10- to 200-nm diameter Au, Ag, and Cu nanospheres, we numerically simulated streaked photoelectron spectra within a quantum-mechanical model. Our spectra show significant oscillation-amplitude enhancements and phase shifts relative to calculations that neglect the induced plasmonic field. We trace these observable effects to the distinct dielectric properties of the three investigated metals, demonstrating the applicability of streaking spectroscopy to the element-specific investigation of induced time-dependent electric fields near nanoparticle surfaces.

  1. Time-resolved spectrophotometry of the AM Herculis system E2003 + 225

    NASA Technical Reports Server (NTRS)

    Mccarthy, Patrick; Bowyer, Stuart; Clarke, John T.

    1986-01-01

    Time-resolved, medium-resolution photometry is reported for the binary system E2003 + 225 over a complete orbital period in 1984. The object was 1.5-2 mag fainter than when viewed earlier in 1984. The fluxes, equivalent widths and full widths at FWHM for dominant lines are presented for four points in the cycle. A coincidence of emission lines and a 4860 A continuum line was observed for the faster component, which had a 500 km/sec velocity amplitude that was symmetric around the zero line. An aberrant emission line component, i.e., stationary narrow emission lines displaced about 9 A from the rest wavelengths, is modeled as Zeeman splitting of emission from material close to the primary.

  2. Quantitative Detection of Nucleoside Analogues by Multi-enzyme Biosensors using Time-Resolved Kinetic Measurements.

    PubMed

    Muthu, Pravin; Lutz, Stefan

    2016-04-05

    Fast, simple and cost-effective methods for detecting and quantifying pharmaceutical agents in patients are highly sought after to replace equipment and labor-intensive analytical procedures. The development of new diagnostic technology including portable detection devices also enables point-of-care by non-specialists in resource-limited environments. We have focused on the detection and dose monitoring of nucleoside analogues used in viral and cancer therapies. Using deoxyribonucleoside kinases (dNKs) as biosensors, our chemometric model compares observed time-resolved kinetics of unknown analytes to known substrate interactions across multiple enzymes. The resulting dataset can simultaneously identify and quantify multiple nucleosides and nucleoside analogues in complex sample mixtures. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Highly time-resolved metabolic reprogramming toward differential levels of phosphate in Chlamydomonas reinhardtii.

    PubMed

    Jang, Cheol-Ho; Lee, Gayeon; Park, Yong-Cheol; Kim, Kyoung Heon; Lee, Do Yup

    2017-04-03

    Understanding phosphorus metabolism in photosynthetic organisms is important in that it is closely associated with enhanced crop productivity and pollution management for natural ecosystems (e.g. algal blooming). Accordingly, we exploited highly time-resolved metabolic responses to different levels of phosphate deprivation in C. reinhardtii, a photosynthetic model organism. We conducted non-targeted primary metabolite profiling using gas-chromatography time-of-flight mass spectrometric analysis. Primarily, we systematically identified main contributors to degree-wise responses corresponding to the deprivation levels of phosphate. And we systematically characterized the metabolite sets of exclusive phosphate condition specificity and interaction with culture time. Among them were various types of fatty acids that were most dynamically modulated by the phosphate availability along with the time-course in addition to phosphorylated compounds.

  4. Time-resolved spectra of single-bubble sonoluminescence in sulfuric acid with a streak camera.

    PubMed

    Chen, Weizhong; Huang, Wei; Liang, Yue; Gao, Xianxian; Cui, Weicheng

    2008-09-01

    The time-resolved spectra of single-bubble sonoluminescence (SBSL) in sulfuric acid have been observed with a streak camera after a spectrograph. The spectral center evolves from infrared to ultraviolet gradually within a SBSL duration, which corresponds to an increase of temperature. The peak temperature within one sonoluminescence (SL) duration is 5-9 times higher than the average temperature based on the average spectrum in our experiment. Furthermore, the ratio of the peak temperature to average temperature increases with the increase of driving pressure. The SBSL flash dies out after a dramatic heating-up, and there is no cooling procedure observed at the time resolution of 110 SL duration, which is incompatible with the radius-related adiabatic heating model as the mechanism of SBSL.

  5. Time-resolved spectra of single-bubble sonoluminescence in sulfuric acid with a streak camera

    NASA Astrophysics Data System (ADS)

    Chen, Weizhong; Huang, Wei; Liang, Yue; Gao, Xianxian; Cui, Weicheng

    2008-09-01

    The time-resolved spectra of single-bubble sonoluminescence (SBSL) in sulfuric acid have been observed with a streak camera after a spectrograph. The spectral center evolves from infrared to ultraviolet gradually within a SBSL duration, which corresponds to an increase of temperature. The peak temperature within one sonoluminescence (SL) duration is 5 9 times higher than the average temperature based on the average spectrum in our experiment. Furthermore, the ratio of the peak temperature to average temperature increases with the increase of driving pressure. The SBSL flash dies out after a dramatic heating-up, and there is no cooling procedure observed at the time resolution of 1/10 SL duration, which is incompatible with the radius-related adiabatic heating model as the mechanism of SBSL.

  6. Time-resolved soft x-ray spectra from laser-produced Cu plasma

    SciTech Connect

    Cone, K. V.; Baldis, H. A.; Dunn, J.; May, M. J.; Schneider, M. B.; Scott, H. A.; Purvis, M. A.

    2012-10-15

    The volumetric heating of a thin copper target has been studied with time resolved x-ray spectroscopy. The copper target was heated by a plasma produced using the Lawrence Livermore National Laboratory's Compact Multipulse Terawatt (COMET) laser. A variable spaced grating spectrometer coupled to an x-ray streak camera measured soft x-ray emission (800-1550 eV) from the back of the copper target to characterize the bulk heating of the target. Radiation hydrodynamic simulations were modeled in two-dimensions using the HYDRA code. The target conditions calculated by HYDRA were post-processed with the atomic kinetics code CRETIN to generate synthetic emission spectra. A comparison between the experimental and simulated spectra indicates the presence of specific ionization states of copper and the corresponding electron temperatures and ion densities throughout the laser-heated copper target.

  7. Time-resolved soft x-ray spectra from laser-produced Cu plasma

    SciTech Connect

    Cone, K V; Dunn, J; Baldis, H A; May, M J; Purvis, M A; Scott, H A; Schneider, M B

    2012-05-02

    The volumetric heating of a thin copper target has been studied with time resolved x-ray spectroscopy. The copper target was heated from a plasma produced using the Lawrence Livermore National Laboratory's Compact Multipulse Terrawatt (COMET) laser. A variable spaced grating spectrometer coupled to an x-ray streak camera measured soft x-ray emission (800-1550 eV) from the back of the copper target to characterize the bulk heating of the target. Radiation hydrodynamic simulations were modeled in 2-dimensions using the HYDRA code. The target conditions calculated by HYDRA were post-processed with the atomic kinetics code CRETIN to generate synthetic emission spectra. A comparison between the experimental and simulated spectra indicates the presence of specific ionization states of copper and the corresponding electron temperatures and ion densities throughout the laser-heated copper target.

  8. Time-resolved soft x-ray spectra from laser-produced Cu plasma.

    PubMed

    Cone, K V; Baldis, H A; Dunn, J; May, M J; Purvis, M A; Schneider, M B; Scott, H A

    2012-10-01

    The volumetric heating of a thin copper target has been studied with time resolved x-ray spectroscopy. The copper target was heated by a plasma produced using the Lawrence Livermore National Laboratory's Compact Multipulse Terawatt (COMET) laser. A variable spaced grating spectrometer coupled to an x-ray streak camera measured soft x-ray emission (800-1550 eV) from the back of the copper target to characterize the bulk heating of the target. Radiation hydrodynamic simulations were modeled in two-dimensions using the HYDRA code. The target conditions calculated by HYDRA were post-processed with the atomic kinetics code CRETIN to generate synthetic emission spectra. A comparison between the experimental and simulated spectra indicates the presence of specific ionization states of copper and the corresponding electron temperatures and ion densities throughout the laser-heated copper target.

  9. Time-resolved analysis and visualization of dynamic processes in living cells

    PubMed Central

    Tvaruskó, W.; Bentele, M.; Misteli, T.; Rudolf, R.; Kaether, C.; Spector, D. L.; Gerdes, H. H.; Eils, R.

    1999-01-01

    Recent development of in vivo microscopy techniques, including green fluorescent proteins, has allowed the visualization of a wide range of dynamic processes in living cells. For quantitative and visual interpretation of such processes, new concepts for time-resolved image analysis and continuous time–space visualization are required. Here, we describe a versatile and fully automated approach consisting of four techniques, namely highly sensitive object detection, fuzzy logic-based dynamic object tracking, computer graphical visualization, and measurement in time–space. Systematic model simulations were performed to evaluate the reliability of the automated object detection and tracking method. To demonstrate potential applications, the method was applied to the analysis of secretory membrane traffic and the functional dynamics of nuclear compartments enriched in pre-mRNA splicing factors. PMID:10393928

  10. Protein analysis by time-resolved measurements with an electro-switchable DNA chip

    PubMed Central

    Langer, Andreas; Hampel, Paul A.; Kaiser, Wolfgang; Knezevic, Jelena; Welte, Thomas; Villa, Valentina; Maruyama, Makiko; Svejda, Matej; Jähner, Simone; Fischer, Frank; Strasser, Ralf; Rant, Ulrich

    2013-01-01

    Measurements in stationary or mobile phases are fundamental principles in protein analysis. Although the immobilization of molecules on solid supports allows for the parallel analysis of interactions, properties like size or shape are usually inferred from the molecular mobility under the influence of external forces. However, as these principles are mutually exclusive, a comprehensive characterization of proteins usually involves a multi-step workflow. Here we show how these measurement modalities can be reconciled by tethering proteins to a surface via dynamically actuated nanolevers. Short DNA strands, which are switched by alternating electric fields, are employed as capture probes to bind target proteins. By swaying the proteins over nanometre amplitudes and comparing their motional dynamics to a theoretical model, the protein diameter can be quantified with Angström accuracy. Alterations in the tertiary protein structure (folding) and conformational changes are readily detected, and even post-translational modifications are revealed by time-resolved molecular dynamics measurements. PMID:23839273

  11. Time-resolved thermal mirror technique with top-hat cw laser excitation.

    PubMed

    Astrath, Francine B; Astrath, Nelson G; Shen, Jun; Zhou, Jianqin; Malacarne, Luis C; Pedreira, P R B; Baesso, Mauro L

    2008-08-04

    A theoretical model was developed for time-resolved thermal mirror spectroscopy under top-hat cw laser excitation that induced a nanoscale surface displacement of a low absorption sample. An additional phase shift to the electrical field of a TEM(00) probe beam reflected from the surface displacement was derived, and Fresnel diffraction theory was used to calculate the propagation of the probe beam. With the theory, optical and thermal properties of three glasses were measured, and found to be consistent with literature values. With a top-hat excitation, an experimental apparatus was developed for either a single thermal mirror or a single thermal lens measurement. Furthermore, the apparatus was used for concurrent measurements of thermal mirror and thermal lens. More physical properties could be measured using the concurrent measurements.

  12. Time-resolved synchrotron radiation X-ray solution scattering study of DNA melting.

    PubMed

    Puigdomenech, J; Perez-Grau, L; Porta, J; Vega, M C; Sicre, P; Koch, M H

    1989-09-01

    Time resolved x-ray solution scattering measurements were made during thermal denaturation of DNA from various sources in the temperature range of 20-90 degrees C. Preliminary results on the influence of fragment length, ionic strength, and origin of the DNA on the time course of the scattering are described. Interpretation is based on model calculations of the scattering patterns. The results indicate that, for long DNA fragments at very low ionic strength, the melting process is a continuous phenomenon over the whole temperature range. It is accompanied by a progressive decrease of the radius of gyration of the cross section and of the mass per unit length. For short fragments of 146 base pair nucleosomal core DNA, stiffening of the DNA appears to precede a sharp melting transition.

  13. Microbeam Studies of Diffusion Time Resolved Ion Beam Induced Charge Collection from Stripe-Like Junctions

    SciTech Connect

    GUO,B.N.; BOUANANI,M.E.; RENFROW,S.N.; WALSH,DAVID S.; DOYLE,BARNEY L.; ATON,T.J.; SMITH,E.B.; BAUMANN,R.C.; DUGGAN,J.L.; MCDANIEL,F.D.

    2000-06-14

    To design more radiation tolerant Integrated Circuits (ICs), it is essential to create and test accurate models of ionizing radiation induced charge collection dynamics within microcircuits. A new technique, Diffusion Time Resolved Ion Beam Induced Charge Collection (DTRIBICC), is proposed to measure the average arrival time of the diffused charge at the junction. Specially designed stripe-like junctions were experimentally studied using a 12 MeV carbon microbeam with a spot size of 1 {micro}m. The relative arrival time of ion-generated charge is measured along with the charge collection using a multiple parameter data acquisition system. The results show the importance of the diffused charge collection by junctions, which is especially significant in accounting for Multiple Bit Upset (MBUs) in digital devices.

  14. Time-resolved IR laser-assisted XUV photoelectron spectroscopy of metal surfaces

    NASA Astrophysics Data System (ADS)

    Zhang, C.-H.; Thumm, U.

    2009-11-01

    Photoemission of localized and delocalized electrons from an (adsorbate-covered) metal surface by an XUV pulse of length τX into the field of a delayed IR laser pulse with carrier period TL allows for the time-resolved observation of surface and adsorbate electronic processes. For τX ≪ TL, the energy of the emitted photoelectrons (PEs) oscillates with period TL as a function of the XUV-IR pulse delay, leading to streaked PE spectra. In contrast, for τX ≳ TL, the PE spectrum is characterized by a satellite structure of sideband peaks located at integer multiples of the IR photon energy from the main photoemission peak. We present a theoretical model that allows us to discuss both, streaked and sideband photoemission spectra in comparison with recent experiments.

  15. Time-resolved near-infrared spectroscopic study of the dissolution of crystalline lactose.

    PubMed

    Hattori, Yusuke; Otsuka, Makoto

    2012-12-18

    In the present study, initial dissolution of crystalline α-lactose monohydrate was investigated via time-resolved Fourier Transform near-infrared (FT-NIR) spectroscopy using the liquid penetration method. The process of water penetration is classically characterized by a two-step increment in the combination bands between OH stretching and bending modes of water; however, only one-step increment in the combination bands was induced by penetration of lactose saturated solution. These results suggest that a first phase occurs in which penetrating water adsorbs to solid lactose surface creating a saturated layer, followed by a second phase of dissolution of the hydrated lactose. Decomposition of differential spectra at 2-min intervals supports the existence of an adsorption-diffusion model and gives a threshold as the amount of adsorbed water to dissolve solid lactose. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Double-layer estimation of intra- and extracerebral hemoglobin concentration with a time-resolved system

    PubMed Central

    Gagnon, Louis; Gauthier, Claudine; Hoge, Rick D.; Lesage, Frédéric; Selb, Juliette; Boas, David A.

    2009-01-01

    We present in vivo measurements of baseline physiology from five subjects with a four-wavelength (690, 750, 800, and 850 nm) time-resolved optical system. The measurements were taken at four distances: 10, 15, 25, and 30 mm. All distances were fit simultaneously with a two-layered analytical model for the absorption and reduced scattering coefficient of both layers. The thickness of the first layer, comprising the skin, scalp, and cerebrospinal fluid, was obtained from anatomical magnetic resonance images. The fitting procedure was first tested with simulations before being applied to in vivo measurements and verified that this procedure permits accurate characterization of the hemoglobin concentrations in the extra- and intracerebral tissues. Baseline oxyhemoglobin, deoxyhemoglobin, and total hemoglobin concentrations and oxygen saturation were recovered from in vivo measurements and compared to the literature. We observed a noticeable intersubject variability of the hemoglobin concentrations, but constant values for the cerebral hemoglobin oxygen saturation. PMID:19021399

  17. Time-resolved measurement of Landau-Zener tunneling in different bases

    SciTech Connect

    Tayebirad, G.; Loerch, N.; Wimberger, S.; Zenesini, A.; Ciampini, D.; Arimondo, E.; Mannella, R.; Morsch, O.

    2010-07-15

    A comprehensive study of the tunneling dynamics of a Bose-Einstein condensate in a tilted periodic potential is presented. We report numerical and experimental results on time-resolved measurements of the Landau-Zener tunneling of ultracold atoms introduced by the tilt, which experimentally is realized by accelerating the lattice. The use of different protocols enables us to access the tunneling probability, numerically as well as experimentally, in two different bases, namely, the adiabatic basis and the diabatic basis. The adiabatic basis corresponds to the eigenstates of the lattice, and the diabatic one to the free-particle momentum eigenstates. Our numerical and experimental results are compared with existing two-state Landau-Zener models.

  18. 3-dimensional bioprinting for tissue engineering applications.

    PubMed

    Gu, Bon Kang; Choi, Dong Jin; Park, Sang Jun; Kim, Min Sup; Kang, Chang Mo; Kim, Chun-Ho

    2016-01-01

    The 3-dimensional (3D) printing technologies, referred to as additive manufacturing (AM) or rapid prototyping (RP), have acquired reputation over the past few years for art, architectural modeling, lightweight machines, and tissue engineering applications. Among these applications, tissue engineering field using 3D printing has attracted the attention from many researchers. 3D bioprinting has an advantage in the manufacture of a scaffold for tissue engineering applications, because of rapid-fabrication, high-precision, and customized-production, etc. In this review, we will introduce the principles and the current state of the 3D bioprinting methods. Focusing on some of studies that are being current application for biomedical and tissue engineering fields using printed 3D scaffolds.

  19. Sub-Nanosecond Time-Resolved Emission Studies with a Mode-Locked CW Dye Laser.

    NASA Astrophysics Data System (ADS)

    Hirsch, Mitchell Dale

    A new technique is developed for time-resolved observation of light emission in the picosecond regime. The technique makes use of optical sum-frequency generation in a crystal having a high non-linear optical dielectric coefficient. The crystal acts as a shutter and provides a time resolution which is limited only by the duration of the light pulses used in the measurement. In this work, the resolution is 10-15 picoseconds. This technique is used in two studies of time -resolved emission from molecules in solution. In the first of these, emission decay curves are obtained for the dye malachite green in solutions of different viscosity. The form of the decay curves is not consistent with a model proposed previously (Th. Foerster and G. Hoffman, Z. Physik. Chem. NF 75, 63 (1961)) to account for the viscosity dependence of the emission quantum efficiency in molecules of this type. The intensity of emission within the first 10 picoseconds following excitation of the molecule is itself observed to decrease with decreasing viscosity. The decrease of the quantum efficiency with decreasing viscosity is shown to be the result of two effects combined: a decrease in overall decay time, which is probably the result of an increasing non-radiative decay rate; and an independent overall reduction in the intensity of emission. Kinetic models for the relaxation processes in the molecule are proposed to account for these findings. In the second study a decay time of 14 (+OR-) 3 picoseconds is measured for emission at room temperature from the molecule bacteriorhodopsin, obtained from the purple membrane of the bacterium Halobacterium Halobium. This result, combined with previous measurements of the quantum efficiency, suggests that the state of the molecule immediately following absorption of a photon and the initial state of the emitting transition are very different in character.

  20. Teleportation of a 3-dimensional GHZ State

    NASA Astrophysics Data System (ADS)

    Cao, Hai-Jing; Wang, Huai-Sheng; Li, Peng-Fei; Song, He-Shan

    2012-05-01

    The process of teleportation of a completely unknown 3-dimensional GHZ state is considered. Three maximally entangled 3-dimensional Bell states function as quantum channel in the scheme. This teleportation scheme can be directly generalized to teleport an unknown d-dimensional GHZ state.

  1. Determination of blood oxygenation in the brain by time-resolved reflectance spectroscopy: influence of the skin, skull, and meninges

    NASA Astrophysics Data System (ADS)

    Hielscher, Andreas H.; Liu, Hanli; Wang, Lihong; Tittel, Frank K.; Chance, Britton; Jacques, Steven L.

    1994-07-01

    Near infrared light has been used for the determination of blood oxygenation in the brain but little attention has been paid to the fact that the states of blood oxygenation in arteries, veins, and capillaries differ substantially. In this study, Monte Carlo simulations for a heterogeneous system were conducted, and near infrared time-resolved reflectance measurements were performed on a heterogeneous tissue phantom model. The model was made of a solid polyester resin, which simulates the tissue background. A network of tubes was distributed uniformly through the resin to simulate the blood vessels. The time-resolved reflectance spectra were taken with different absorbing solutions filled in the network. Based on the simulation and experimental results, we investigated the dependence of the absorption coefficient obtained from the heterogeneous system on the absorption of the actual absorbing solution filled in the tubes. We show that light absorption by the brain should result from the combination of blood and blood-free tissue background.

  2. Frame-Transfer Gating Raman Spectroscopy for Time-Resolved Multiscalar Combustion Diagnostics

    NASA Technical Reports Server (NTRS)

    Nguyen, Quang-Viet; Fischer, David G.; Kojima, Jun

    2011-01-01

    Accurate experimental measurement of spatially and temporally resolved variations in chemical composition (species concentrations) and temperature in turbulent flames is vital for characterizing the complex phenomena occurring in most practical combustion systems. These diagnostic measurements are called multiscalar because they are capable of acquiring multiple scalar quantities simultaneously. Multiscalar diagnostics also play a critical role in the area of computational code validation. In order to improve the design of combustion devices, computational codes for modeling turbulent combustion are often used to speed up and optimize the development process. The experimental validation of these codes is a critical step in accepting their predictions for engine performance in the absence of cost-prohibitive testing. One of the most critical aspects of setting up a time-resolved stimulated Raman scattering (SRS) diagnostic system is the temporal optical gating scheme. A short optical gate is necessary in order for weak SRS signals to be detected with a good signal- to-noise ratio (SNR) in the presence of strong background optical emissions. This time-synchronized optical gating is a classical problem even to other spectroscopic techniques such as laser-induced fluorescence (LIF) or laser-induced breakdown spectroscopy (LIBS). Traditionally, experimenters have had basically two options for gating: (1) an electronic means of gating using an image intensifier before the charge-coupled-device (CCD), or (2) a mechanical optical shutter (a rotary chopper/mechanical shutter combination). A new diagnostic technology has been developed at the NASA Glenn Research Center that utilizes a frame-transfer CCD sensor, in conjunction with a pulsed laser and multiplex optical fiber collection, to realize time-resolved Raman spectroscopy of turbulent flames that is free from optical background noise (interference). The technology permits not only shorter temporal optical gating (down

  3. Monolithic Microfluidic Mixing-Spraying Devices for Time-Resolved Cryo-Electron Microscopy

    PubMed Central

    Lu, Zonghuan; Shaikh, Tanvir R.; Barnard, David; Meng, Xing; Mohamed, Hisham; Yassin, Aymen; Mannella, Carmen A.; Agrawal, Rajendra K.; Lu, Toh-Ming

    2009-01-01

    The goal of time-resolved cryo-electron microscopy is to determine structural models for transient functional states of large macromolecular complexes such as ribosomes and viruses. The challenge of time-resolved cryo-electron microscopy is to rapidly mix reactants, and then, following a defined time interval, to rapidly deposit them as a thin film and freeze the sample to the vitreous state. Here we describe a methodology in which reaction components are mixed and allowed to react, and are then sprayed onto an EM grid as it is being plunged into cryogen. All steps are accomplished by a monolithic, microfabricated silicon device that incorporates a mixer, reaction channel, and pneumatic sprayer in a single chip. We have found that microdroplets produced by air atomization spread to sufficiently thin films on a millisecond time scale provided that the carbon supporting film is made suitably hydrophilic. The device incorporates two T-mixers flowing into a single channel of four butterfly-shaped mixing elements that ensure effective mixing, followed by a microfluidic reaction channel whose length can be varied to achieve the desired reaction time. The reaction channel is flanked by two ports connected to compressed humidified nitrogen gas (at 50 psi) to generate the spray. The monolithic mixer-sprayer is incorporated into a computer-controlled plunging apparatus. To test the mixing performance and the suitability of the device for preparation of biological macromolecules for cryo-EM, ribosomes and ferritin were mixed in the device and sprayed onto grids. Three-dimensional reconstructions of the ribosomes demonstrated retention of native structure, and 30S and 50S subunits were shown to be capable of reassociation into ribosomes after passage through the device. PMID:19683579

  4. Protein structural dynamics in solution unveiled via 100-ps time-resolved x-ray scattering

    SciTech Connect

    Cho, Hyun Sun; Dashdorj, Naranbaatar; Schotte, Friedrich; Graber, Timothy; Henning, Robert; Anfinruda, Philip

    2010-04-21

    We have developed a time-resolved x-ray scattering diffractometer capable of probing structural dynamics of proteins in solution with 100-ps time resolution. This diffractometer, developed on the ID14B BioCARS (Consortium for Advanced Radiation Sources) beamline at the Advanced Photon Source, records x-ray scattering snapshots over a broad range of q spanning 0.02-2.5 {angstrom}{sup -1}, thereby providing simultaneous coverage of the small-angle x-ray scattering (SAXS) and wide-angle x-ray scattering (WAXS) regions. To demonstrate its capabilities, we have tracked structural changes in myoglobin as it undergoes a photolysis-induced transition from its carbon monoxy form (MbCO) to its deoxy form (Mb). Though the differences between the MbCO and Mb crystal structures are small (rmsd < 0.2 {angstrom}), time-resolved x-ray scattering differences recorded over 8 decades of time from 100 ps to 10 ms are rich in structure, illustrating the sensitivity of this technique. A strong, negative-going feature in the SAXS region appears promptly and corresponds to a sudden > 22 {angstrom}{sup 3} volume expansion of the protein. The ensuing conformational relaxation causes the protein to contract to a volume {approx}2 {angstrom}{sup 3} larger than MbCO within {approx}10 ns. On the timescale for CO escape from the primary docking site, another change in the SAXS/WAXS fingerprint appears, demonstrating sensitivity to the location of the dissociated CO. Global analysis of the SAXS/WAXS patterns recovered time-independent scattering fingerprints for four intermediate states of Mb. These SAXS/WAXS fingerprints provide stringent constraints for putative models of conformational states and structural transitions between them.

  5. An integrated approach using high time-resolved tools to study the origin of aerosols.

    PubMed

    Di Gilio, A; de Gennaro, G; Dambruoso, P; Ventrella, G

    2015-10-15

    Long-range transport of natural and/or anthropogenic particles can contribute significantly to PM10 and PM2.5 concentrations and some European cities often fail to comply with PM daily limit values due to the additional impact of particles from remote sources. For this reason, reliable methodologies to identify long-range transport (LRT) events would be useful to better understand air pollution phenomena and support proper decision-making. This study explores the potential of an integrated and high time-resolved monitoring approach for the identification and characterization of local, regional and long-range transport events of high PM. In particular, the goal of this work was also the identification of time-limited event. For this purpose, a high time-resolved monitoring campaign was carried out at an urban background site in Bari (southern Italy) for about 20 days (1st-20th October 2011). The integration of collected data as the hourly measurements of inorganic ions in PM2.5 and their gas precursors and of the natural radioactivity, in addition to the analyses of aerosol maps and hourly back trajectories (BT), provided useful information for the identification and chemical characterization of local sources and trans-boundary intrusions. Non-sea salt (nss) sulfate levels were found to increase when air masses came from northeastern Europe and higher dispersive conditions of the atmosphere were detected. Instead, higher nitrate and lower nss-sulfate concentrations were registered in correspondence with air mass stagnation and attributed to local traffic source. In some cases, combinations of local and trans-boundary sources were observed. Finally, statistical investigations such as the principal component analysis (PCA) applied on hourly ion concentrations and the cluster analyses, the Potential Source Contribution Function (PSCF) and the Concentration Weighted Trajectory (CWT) models computed on hourly back-trajectories enabled to complete a cognitive framework

  6. Labial morphology: a 3-dimensional anthropometric study.

    PubMed

    Ferrario, Virgilio F; Rosati, Riccardo; Peretta, Redento; Dellavia, Claudia; Sforza, Chiarella

    2009-09-01

    To develop a noninvasive 3-dimensional method to evaluate labial morphology and to assess gender-related differences in healthy young adults. Dental and lip impressions of 11 men and 10 women aged 21 to 34 years, with sound, full, permanent dentition were obtained. The models were digitized and 3-dimensional virtual reproductions obtained. The labial thickness, vermilion area, and volume of the upper and lower lips were measured from the digital reconstructions. The male and female data were compared using Student's t test. The mean lip thickness was significantly larger (P = .02) in men (14.3 mm) than in women (12.3 mm). The lower lip was thicker than the upper lip. The vermilion width was larger in men (75 mm) than in women (70 mm), and no differences were found for vermilion height (10 mm). In the upper lip, the height/width ratio was significantly larger in women (14.1%) than in men (12.3%). The vermilion surface area was slightly larger in men than in women (upper lip area: women, 467 mm(2); men, 501 mm(2); lower lip area: women, 491 mm(2); men, 569 mm(2)). The labial volume was significantly larger in men (upper lip, 2,390 mm(3); lower lip, 2,902 mm(3)) than in women (upper lip, 1,743 mm(3); lower lip, 1,764 mm(3); P = .021). The upper/lower lip area and volume ratios were similar in the 2 genders. Overall, men had larger lips than women. The inferior lip height/width ratio was similar in both genders, and men had a relatively thinner upper lip than women.

  7. Time-resolved structural studies of protein reaction dynamics: a smorgasbord of X-ray approaches

    SciTech Connect

    Westenhoff, Sebastian; Nazarenko, Elena; Malmerberg, Erik; Davidsson, Jan; Katona, Gergely; Neutze, Richard

    2010-03-01

    Time-resolved structural studies of proteins have undergone several significant developments during the last decade. Recent developments using time-resolved X-ray methods, such as time-resolved Laue diffraction, low-temperature intermediate trapping, time-resolved wide-angle X-ray scattering and time-resolved X-ray absorption spectroscopy, are reviewed. Proteins undergo conformational changes during their biological function. As such, a high-resolution structure of a protein’s resting conformation provides a starting point for elucidating its reaction mechanism, but provides no direct information concerning the protein’s conformational dynamics. Several X-ray methods have been developed to elucidate those conformational changes that occur during a protein’s reaction, including time-resolved Laue diffraction and intermediate trapping studies on three-dimensional protein crystals, and time-resolved wide-angle X-ray scattering and X-ray absorption studies on proteins in the solution phase. This review emphasizes the scope and limitations of these complementary experimental approaches when seeking to understand protein conformational dynamics. These methods are illustrated using a limited set of examples including myoglobin and haemoglobin in complex with carbon monoxide, the simple light-driven proton pump bacteriorhodopsin, and the superoxide scavenger superoxide reductase. In conclusion, likely future developments of these methods at synchrotron X-ray sources and the potential impact of emerging X-ray free-electron laser facilities are speculated upon.

  8. Application of Time-resolved PIV to Supersonic Hot Jets

    NASA Technical Reports Server (NTRS)

    Bridges, James; Wernet, Mark P.

    2007-01-01

    This presentation lays out the ground-breaking work at bringing high-speed (25kHz) particle image velocimetry (PIV) to bear on measurements of noise-producing turbulence in hot jets. The work is still in progress in that the tremendous amount of data obtained are still be analyzed, but the method has been validated and initial results of interest to jet noise modeling have been obtained. After a brief demonstration of the validation process used on the data, results are shown for hot jets at different temperatures and Mach numbers. Comparisons of first order statistics show the relative indifference of the turbulence to the presence of shocks and independence to jet temperature. What does come out is that when the shock-containing jets are in a screech mode the turbulence is highly elevated, showing the importance of removing screech phenomena from model-scale jets before applying findings to full-scale aircraft which typically do not contain shocks.

  9. Reference optical phantoms for diffuse optical spectroscopy. Part 1--Error analysis of a time resolved transmittance characterization method.

    PubMed

    Bouchard, Jean-Pierre; Veilleux, Israël; Jedidi, Rym; Noiseux, Isabelle; Fortin, Michel; Mermut, Ozzy

    2010-05-24

    Development, production quality control and calibration of optical tissue-mimicking phantoms require a convenient and robust characterization method with known absolute accuracy. We present a solid phantom characterization technique based on time resolved transmittance measurement of light through a relatively small phantom sample. The small size of the sample enables characterization of every material batch produced in a routine phantoms production. Time resolved transmittance data are pre-processed to correct for dark noise, sample thickness and instrument response function. Pre-processed data are then compared to a forward model based on the radiative transfer equation solved through Monte Carlo simulations accurately taking into account the finite geometry of the sample. The computational burden of the Monte-Carlo technique was alleviated by building a lookup table of pre-computed results and using interpolation to obtain modeled transmittance traces at intermediate values of the optical properties. Near perfect fit residuals are obtained with a fit window using all data above 1% of the maximum value of the time resolved transmittance trace. Absolute accuracy of the method is estimated through a thorough error analysis which takes into account the following contributions: measurement noise, system repeatability, instrument response function stability, sample thickness variation refractive index inaccuracy, time correlated single photon counting system time based inaccuracy and forward model inaccuracy. Two sigma absolute error estimates of 0.01 cm(-1) (11.3%) and 0.67 cm(-1) (6.8%) are obtained for the absorption coefficient and reduced scattering coefficient respectively.

  10. Resonant and Time-Resolved Spin Noise Spectroscopy

    NASA Astrophysics Data System (ADS)

    Song, Xinlin; Pursley, Brennan; Sih, Vanessa

    Spin noise spectroscopy is a technique which can probe the system while it remains in equilibrium. It was first demonstrated in atomic gases and then in solid state systems. Most existing spin noise measurement setups digitize the spin fluctuation signal and then analyze the power spectrum. Recently, pulsed lasers have been used to expand the bandwidth of accessible dynamics and allow direct time-domain correlation measurements. Here we develop and test a model for ultrafast pulsed laser spin noise measurements as well as a scheme to measure spin lifetimes longer than the laser repetition period. For the resonant spin noise technique, analog electronics are used to capture correlations from the extended pulse train, and the signal at a fixed time delay is measured as a function of applied magnetic field.

  11. 3-dimensional Oil Drift Simulations

    NASA Astrophysics Data System (ADS)

    Wettre, C.; Reistad, M.; Hjøllo, B.Å.

    Simulation of oil drift has been an ongoing activity at the Norwegian Meteorological Institute since the 1970's. The Marine Forecasting Centre provides a 24-hour service for the Norwegian Pollution Control Authority and the oil companies operating in the Norwegian sector. The response time is 30 minutes. From 2002 the service is extended to simulation of oil drift from oil spills in deep water, using the DeepBlow model developed by SINTEF Applied Chemistry. The oil drift model can be applied both for instantaneous and continuous releases. The changes in the mass of oil and emulsion as a result of evaporation and emulsion are computed. For oil spill at deep water, hydrate formation and gas dissolution are taken into account. The properties of the oil depend on the oil type, and in the present version 64 different types of oil can be simulated. For accurate oil drift simulations it is important to have the best possible data on the atmospheric and oceanic conditions. The oil drift simulations at the Norwegian Meteorological Institute are always based on the most updated data from numerical models of the atmosphere and the ocean. The drift of the surface oil is computed from the vectorial sum of the surface current from the ocean model and the wave induced Stokes drift computed from wave energy spectra from the wave prediction model. In the new model the current distribution with depth is taken into account when calculating the drift of the dispersed oil droplets. Salinity and temperature profiles from the ocean model are needed in the DeepBlow model. The result of the oil drift simulations can be plotted on sea charts used for navigation, either as trajectory plots or particle plots showing the situation at a given time. The results can also be sent as data files to be included in the user's own GIS system.

  12. Ultimate sensitivity of time-resolved optoacoustic detection

    NASA Astrophysics Data System (ADS)

    Oraevsky, Alexander A.; Karabutov, Alexander A.

    2000-05-01

    The major limitation in sensitivity of the optical tomography is associated with strong optical attenuation in human tissues. Opto-acoustic tomography overcomes this limitation utilizing detection of acoustic waves instead of detection of transmitted photons. Exceptional sensitivity of the opto-acoustic tomography allows early detection of small tumors located dep in human tissues, such as breast. This paper demonstrates that an optimally designed opto-acoustic imaging system can detect early 1-mm tumors with minimal blood content of only 7 percent at the depth of up to 7-cm within the breast attenuating laser irradiation 3.3 times per each 1-cm of its depth. A theoretical consideration of the ultimate sensitivity of piezo-detection in a wide ultrasonic frequency band is developed. The detection sensitivity is presented as a function of the ultrasonic frequency, tumor dimensions and optical absorption coefficient. Comparative analysis of piezo and optical interferometric detection of opto-acoustic transients is presented. The theoretical models of piezo detection were developed for the open-circuit and short-circuit schemes of operation. The ultimate sensitivity limited by thermal noise of electric capacitor of the piezo-element was estimated. It was shown that the limit of detection depends on the frequency band, the electric capacity of the transducer and the sped of sound in the piezo-element. Comparative analysis of various piezo-materials was made from the point of view of their utility for sensitive opto-acoustic detection.

  13. Non-invasive measurement of blood glucose level by time-resolved transmission spectroscopy: A feasibility study

    NASA Astrophysics Data System (ADS)

    Sun, Meixiu; Chen, Nanguang

    2012-03-01

    An optical spectroscopic method is investigated theoretically for in vivo measurement of blood glucose concentration. This method is based on dynamic dual wavelength (610 nm and 810 nm) time-resolved measurements under a condition of artificial blood flow kinetics in a human finger. The influence of glucose concentration on absorption and reduced scattering coefficients of the whole blood is simulated using the T-matrix method. The scattering centers, RBC aggregation, under the artificial — kinetics condition are modeled as spheroid. The modified parametric slopes were derived from the Laplace transformed data of the time-resolved transmittance. The results show that an appropriate selection of the Laplace parameter can lead to enhanced sensitivity for glucose measurement.

  14. The use of time-resolved X-ray diffraction and sample techniques for studying the muscle structure during relaxation

    NASA Astrophysics Data System (ADS)

    Vazina, A. A.; Gadzhiev, A. M.; Gerasimov, V. S.; Gorbunova, N. P.; Sergienko, P. M.; Korneev, V. N.; Aulchenko, V. M.; Baru, S. E.

    1995-02-01

    The use of the modern time-resolved X-ray diffraction and sample technique has played an important role in studying muscle structures during contraction at various physiological conditions. We represent time-resolved X-ray data on equatorial diffraction and tension response of the frog sartorius muscle during relaxation. The measurements of the time-course of the intensity change of reflections (1,0), (1,1) and the background under them give a possibility to study the effect of potentiation of contraction by repetitive stimulation in fresh and tired muscles. Model calculations of meridional diffraction patterns for various configurations of cross-bridges in the relaxation phase were carried out.

  15. Time-resolved contrast function and optical characterization of spatially varying absorptive inclusions at different depths in diffusing media.

    PubMed

    De Nicola, S; Esposito, R; Lepore, M; Indovina, P L

    2004-03-01

    The role of a spatially varying absorptive inhomogeneity located at different depths within a turbid material has been investigated. This inhomogeneity has been characterized by a spatially dependent Gaussian distribution of its absorption coefficient. The present study has been performed calculating the time-resolved contrast function in the framework of the first-order perturbative approach to the diffusion equation for a slab geometry and a coaxial measurement scheme. The model has allowed us to take into account different locations of the inclusion along the source-detector axis. The accuracy of time-resolved contrast predictions has been analyzed through comparisons with results of the finite element method that has been used to numerically solve the diffusion equation. Recovery of the absorption perturbation parameter of the inhomogeneity for different axial positions has also been investigated.

  16. Time-resolved contrast enhanced magnetic resonance angiography of the head and neck at 3.0 tesla: initial results.

    PubMed

    Nael, Kambiz; Michaely, Henrik J; Villablanca, Pablo; Salamon, Noriko; Laub, Gerhard; Finn, J Paul

    2006-02-01

    We sought to implement and evaluate a high-performance, extended field of view protocol for time-resolved contrast-enhanced magnetic resonance imaging (CEMRA) of the carotid circulation by using a dedicated neurovascular (NV) array coil. A total of 16 adult volunteers and 20 clinical patients with suspected cerebrovascular disease (15 male, 21 female, 25-82 years of age) were scanned with a fast 3D MRA sequence (TR/TE: 2.16/1 milliseconds, sampling BW: 1090 Hz/pixel), with echo-sharing and parallel acquisition. All studies were performed on a 3.0 T MR system using an 8-channel neurovascular array coil. After injection of 6 mL of gadodiamide at 3 mL/s, a coronal 3D data set with in-plane resolution of 1 x 1.3 was implemented for 10 consecutive measurements each 1.8 seconds apart. The subjects subsequently underwent high spatial-resolution (in-plane: 0.8 x 0.9) CEMRA for comparative analysis. The quality of segmental arterial anatomy and the presence and degree of the arterial stenosis were evaluated by 2 neuroradiologists. The interobserver variability was tested by kappa statistics and comparative analysis between the TR-CEMRA and high spatial-resolution CEMRA was evaluated by mean of the Spearman rank correlation coefficient. Craniocervical arteries were visualized with good image quality and definition in the diagnostic range. Occlusive disease was detected in 42 (reader A) and 44 (reader B) arterial segments with excellent interobserver agreement (kappa =0.89; 95% confidence interval 0.82-0.96). There was a significant correlation between the TR-CEMRA and high spatial-resolution CEMRA (Rs = 0.91 and 0.93, for readers A and B, respectively) for the degree of stenosis. Three aneurysms, 3 AVMs, 1 AV-fistula, and 2 subclavian steals were detected by both observers and were confirmed by correlative imaging. Time-resolved CEMRA at 3.0 T is reliable and versatile, providing 3-dimensional time-resolved data sets with high spatial (in plane: 1.3 x 1 mm2) and temporal (1

  17. Radical ions and excited states in radiolysis. Optically detected time resolved EPR

    SciTech Connect

    Trifunac, A.D.; Smith, J.P.

    1981-01-01

    Excited-state production and radical-ion recombination kinetics in pulse-irradiated solutions of aromatic solutes in cyclohexane are studied by a new method of optical detection of time-resolved electron paramagnetic resonance (EPR) spectra. 7 figures.

  18. Time-resolved spectroscopy of the fluorescence quenching of a donor — acceptor pair by halothane

    NASA Astrophysics Data System (ADS)

    Sharma, A.; Draxler, S.; Lippitsch, M. E.

    1992-04-01

    Donor (anthracene) sensitized acceptor (perylene) fluorescence is quenched more efficiently by halothane than is intrinsic perylene fluorescence. The underlying process of dynamic fluorescence quenching is investigated by time-resolved fluorescence spectroscopy.

  19. An inexpensive technique for the time resolved laser induced plasma spectroscopy

    SciTech Connect

    Ahmed, Rizwan Ahmed, Nasar; Iqbal, J.; Aslam Baig, M.

    2016-08-15

    We present an efficient and inexpensive method for calculating the time resolved emission spectrum from the time integrated spectrum by monitoring the time evolution of neutral and singly ionized species in the laser produced plasma. To validate our assertion of extracting time resolved information from the time integrated spectrum, the time evolution data of the Cu II line at 481.29 nm and the molecular bands of AlO in the wavelength region (450–550 nm) have been studied. The plasma parameters were also estimated from the time resolved and time integrated spectra. A comparison of the results clearly reveals that the time resolved information about the plasma parameters can be extracted from the spectra registered with a time integrated spectrograph. Our proposed method will make the laser induced plasma spectroscopy robust and a low cost technique which is attractive for industry and environmental monitoring.

  20. Time Resolved Studies of Bright Short Gamma Ray Bursts in the Fermi Gamma Ray Burst Monitor

    NASA Astrophysics Data System (ADS)

    Burns, E.; Connaughton, V.; Preece, R.; Goldstein, A.

    2016-10-01

    We present preliminary results on using a Bayesian Block representation of Fermi GBM data to select intervals for time resolved analysis of short GRBs. Additionally, we search for possible precursor and extended emission in short GRBs.

  1. Phase-locked 10 MHz reference signal for frequency domain time-resolved fluorescence measurements

    NASA Astrophysics Data System (ADS)

    Smith, Trevor A.; Bird, Damian K.; Nuske, John W.

    2007-05-01

    A complete electronic system that is suitable for use in megahertz frequency domain time-resolved fluorescence instruments based on mode-locked lasers is described. The circuit produces a 10MHz signal, phase locked to the mode-locked laser pulse frequency, which is required by many commercial frequency synthesizers as the external reference signal. This device is particularly useful in conjunction with ultrafast gated intensified charge coupled device cameras capable of being frequency modulated for time-resolved fluorescence imaging.

  2. Object classification through scattering media with deep learning on time resolved measurement.

    PubMed

    Satat, Guy; Tancik, Matthew; Gupta, Otkrist; Heshmat, Barmak; Raskar, Ramesh

    2017-07-24

    We demonstrate an imaging technique that allows identification and classification of objects hidden behind scattering media and is invariant to changes in calibration parameters within a training range. Traditional techniques to image through scattering solve an inverse problem and are limited by the need to tune a forward model with multiple calibration parameters (like camera field of view, illumination position etc.). Instead of tuning a forward model and directly inverting the optical scattering, we use a data driven approach and leverage convolutional neural networks (CNN) to learn a model that is invariant to calibration parameters variations within the training range and nearly invariant beyond that. This effectively allows robust imaging through scattering conditions that is not sensitive to calibration. The CNN is trained with a large synthetic dataset generated with a Monte Carlo (MC) model that contains random realizations of major calibration parameters. The method is evaluated with a time-resolved camera and multiple experimental results are provided including pose estimation of a mannequin hidden behind a paper sheet with 23 correct classifications out of 30 tests in three poses (76.6% accuracy on real-world measurements). This approach paves the way towards real-time practical non line of sight (NLOS) imaging applications.

  3. 3DHYDROGEOCHEM: A 3-DIMENSIONAL MODEL OF DENSITY-DEPENDENT SUBSURFACE FLOW AND THERMAL MULTISPECIES-MULTICOMPONENT HYDROGEOCHEMICAL TRANSPORT (EPA/600/SR-98/159)

    EPA Science Inventory

    This report presents a three-dimensional finite-element numerical model designed to simulate chemical transport in subsurface systems with temperature effect taken into account. The three-dimensional model is developed to provide (1) a tool of application, with which one is able ...

  4. 3DHYDROGEOCHEM: A 3-DIMENSIONAL MODEL OF DENSITY-DEPENDENT SUBSURFACE FLOW AND THERMAL MULTISPECIES-MULTICOMPONENT HYDROGEOCHEMICAL TRANSPORT (EPA/600/SR-98/159)

    EPA Science Inventory

    This report presents a three-dimensional finite-element numerical model designed to simulate chemical transport in subsurface systems with temperature effect taken into account. The three-dimensional model is developed to provide (1) a tool of application, with which one is able ...

  5. Steady state and time resolved optical characterization studies of Zn2SnO4 nanowires for solar cell applications

    NASA Astrophysics Data System (ADS)

    Yakami, Baichhabi R.; Poudyal, Uma; Nandyala, Shashank R.; Rimal, Gaurab; Cooper, Jason K.; Zhang, Xuejie; Wang, Jing; Wang, Wenyong; Pikal, Jon M.

    2016-10-01

    Nanowires are a promising option for sensitized solar cells, sensors, and display technology. Most of the work thus far has focused on binary oxides for these nanowires, but ternary oxides have advantages in additional control of optical and electronic properties. Here, we report on the diffuse reflectance, Low Temperature and Room Temperature Photoluminescence (PL), PL excitation spectrum, and Time Resolved PL (TRPL) of Zinc Tin Oxide (ZTO) nanowires grown by Chemical Vapor Deposition. The PL from the ZTO nanowires does not exhibit any band gap or near gap emission, and the diffuse reflectance measurement confirms that these ZTO nanowires have a direct forbidden transition. The broad PL spectrum reveals two Gaussian peaks centered at 1.86 eV (red) and 2.81 eV (blue), representing two distinct defect states or complexes. The PL spectra were further studied by the Time Resolved Emission Spectrum and intensity dependent PL and TRPL. The time resolved measurements show complex non-exponential decays at all wavelengths, indicative of defect to defect transitions, and the red emissive states decay much slower than the blue emissive states. The effects of annealing in air and vacuum are studied to investigate the origin of the defect states in the nanowires, showing that the blue states are related to oxygen vacancies. We propose an energy band model for the nanowires containing defect states within the band gap and the associated transitions between these states that are consistent with our measurements.

  6. Steady state and time resolved optical characterization studies of Zn2SnO4 nanowires for solar cell applications

    DOE PAGES

    Yakami, Baichhabi R.; Poudyal, Uma; Nandyala, Shashank R.; ...

    2016-10-25

    Nanowires are a promising option for sensitized solar cells, sensors, and display technology. Most of the work thus far has focused on binary oxides for these nanowires, but ternary oxides have advantages in additional control of optical and electronic properties. Here, we report on the diffuse reflectance, Low Temperature and Room Temperature Photoluminescence (PL), PL excitation spectrum, and Time Resolved PL (TRPL) of Zinc Tin Oxide (ZTO) nanowires grown by Chemical Vapor Deposition. The PL from the ZTO nanowires does not exhibit any band gap or near gap emission, and the diffuse reflectance measurement confirms that these ZTO nanowires havemore » a direct forbidden transition. The broad PL spectrum reveals two Gaussian peaks centered at 1.86 eV (red) and 2.81 eV (blue), representing two distinct defect states or complexes. The PL spectra were further studied by the Time Resolved Emission Spectrum and intensity dependent PL and TRPL. The time resolved measurements show complex non-exponential decays at all wavelengths, indicative of defect to defect transitions, and the red emissive states decay much slower than the blue emissive states. The effects of annealing in air and vacuum are studied to investigate the origin of the defect states in the nanowires, showing that the blue states are related to oxygen vacancies. We propose an energy band model for the nanowires containing defect states within the band gap and the associated transitions between these states that are consistent with our measurements.« less

  7. Femtosecond time-resolved ionization spectroscopy of ultrafast internal-conversion dynamics in polyatomic molecules: Theory and computational studies

    NASA Astrophysics Data System (ADS)

    Seel, Matthias; Domcke, Wolfgang

    1991-12-01

    A framework for the theoretical description of two-pulse time-resolved ionization spectroscopy of ultrafast excited-state dynamics of polyatomic molecules is developed. The radiation-matter interaction as well as intramolecular couplings in the excited-state manifold are treated nonperturbatively by solving the time-dependent Schrödinger equation. The numerical solution is based on a discretization of the ionization continua which becomes particularly efficient for ultrashort laser pulses. With this method converged computations of ionization signals become possible even for complex molecular systems. Computer simulations are performed for a model system representing three-dimensional non-Born-Oppenheimer excited-state dynamics on conically intersecting potential-energy surfaces (the S1 and S2 surfaces of pyrazine). The dependence of the observable time-resolved ionization signals (total ion yield as well as photoelectron spectrum) on the properties of the laser pulses (carrier frequency and pulse duration) is explored. It is demonstrated that ultrafast electronic decay processes as well as coherent vibrational motion in excited states can be monitored by pump-probe ionization with suitable pulses. The dependence of the time-resolved ionization signals on properties of the cation (ionization potentials and potential-energy surfaces) is also discussed.

  8. Phase diagram of quark-antiquark and diquark condensates in the 3-dimensional Gross-Neveu model with the 4-component spinor representation

    SciTech Connect

    Kohyama, Hiroaki

    2008-07-01

    We construct the phase diagram of the quark-antiquark and diquark condensates at finite temperature and density in the 2+1 dimensional (3D) two flavor massless Gross-Neveu (GN) model with the 4-component quarks. In contrast to the case of the 2-component quarks, there appears the coexisting phase of the quark-antiquark and diquark condensates. This is the crucial difference between the 2-component and 4-component quark cases in the 3D GN model. The coexisting phase is also seen in the 4D Nambu Jona-Lasinio model. Then we see that the 3D GN model with the 4-component quarks bears closer resemblance to the 4D Nambu Jona-Lasinio model.

  9. [A method for time-resolved laser-induced breakdown spectroscopy measurement].

    PubMed

    Pan, Cong-Yuan; Han, Zhen-Yu; Li, Chao-Yang; Yu, Yun-Si; Wang, Sheng-Bo; Wang, Qiu-Ping

    2014-04-01

    Laser-Induced Breakdown Spectroscopy (LIBS) is strongly time related. Time-resolved LIBS measurement is an important technique for the research on laser induced plasma evolution and self-absorption of the emission lines. Concerning the temporal characteristics of LIBS spectrum, a method is proposed in the present paper which can achieve micros-scale time-resolved LIBS measurement by using general ms-scale detector. By setting different integration delay time of the ms-scale spectrum detector, a series of spectrum are recorded. And the integration delay time interval should be longer than the worst temporal precision. After baseline correction and spectrum fitting, the intensity of the character line was obtained. Calculating this intensity with differential method at a certain time interval and then the difference value is the time-resolved line intensity. Setting the plasma duration time as X-axis and the time-resolved line intensity as Y-axis, the evolution curve of the character line intensity can be plotted. Character line with overlap-free and smooth background should be a priority to be chosen for analysis. Using spectrometer with ms-scale integration time and a control system with temporal accuracy is 0.021 micros, experiments carried out. The results validate that this method can be used to characterize the evolution of LIBS characteristic lines and can reduce the cost of the time-resolved LIBS measurement system. This method makes high time-resolved LIBS spectrum measurement possible with cheaper system.

  10. Utility of a 3-dimensional full-scale NaCl model for rib strut grafting for anterior fusion for cervicothoracic kyphosis

    PubMed Central

    Kobayashi, Kazuyoshi; Imagama, Shiro; Muramoto, Akio; Ito, Zenya; Ando, Kei; Yagi, Hideki; Hida, Tetsuro; Ito, Kenyu; Ishikawa, Yoshimoto; Tsushima, Mikito; Ishiguro, Naoki

    2015-01-01

    ABSTRACT In severe spinal deformity, pain and neurological disorder may be caused by spinal cord compression. Surgery for spinal reconstruction is desirable, but may be difficult in a case with severe deformity. Here, we show the utility of a 3D NaCl (salt) model in preoperative planning of anterior reconstruction using a rib strut in a 49-year-old male patient with cervicothoracic degenerative spondylosis. We performed surgery in two stages: a posterior approach with decompression and posterior instrumentation with a pedicle screw; followed by a second operation using an anterior approach, for which we created a 3D NaCl model including the cervicothoracic lesion, spinal deformity, and ribs for anterior reconstruction. The 3D NaCl model was easily scraped compared with a conventional plaster model and was useful for planning of resection and identification of a suitable rib for grafting in a preoperative simulation. Surgery was performed successfully with reference to the 3D NaCl model. We conclude that preoperative simulation with a 3D NaCl model contributes to performance of anterior reconstruction using a rib strut in a case of cervicothoracic deformity. PMID:26412901

  11. A 3-dimensional trimeric β-barrel model for Chlamydia MOMP contains conserved and novel elements of Gram-negative bacterial porins.

    PubMed

    Feher, Victoria A; Randall, Arlo; Baldi, Pierre; Bush, Robin M; de la Maza, Luis M; Amaro, Rommie E

    2013-01-01

    Chlamydia trachomatis is the most prevalent cause of bacterial sexually transmitted diseases and the leading cause of preventable blindness worldwide. Global control of Chlamydia will best be achieved with a vaccine, a primary target for which is the major outer membrane protein, MOMP, which comprises ~60% of the outer membrane protein mass of this bacterium. In the absence of experimental structural information on MOMP, three previously published topology models presumed a16-stranded barrel architecture. Here, we use the latest β-barrel prediction algorithms, previous 2D topology modeling results, and comparative modeling methodology to build a 3D model based on the 16-stranded, trimeric assumption. We find that while a 3D MOMP model captures many structural hallmarks of a trimeric 16-stranded β-barrel porin, and is consistent with most of the experimental evidence for MOMP, MOMP residues 320-334 cannot be modeled as β-strands that span the entire membrane, as is consistently observed in published 16-stranded β-barrel crystal structures. Given the ambiguous results for β-strand delineation found in this study, recent publications of membrane β-barrel structures breaking with the canonical rule for an even number of β-strands, findings of β-barrels with strand-exchanged oligomeric conformations, and alternate folds dependent upon the lifecycle of the bacterium, we suggest that although the MOMP porin structure incorporates canonical 16-stranded conformations, it may have novel oligomeric or dynamic structural changes accounting for the discrepancies observed.

  12. In vivo reconstruction of NIR FRET using full-field time resolved optical tomography

    NASA Astrophysics Data System (ADS)

    Venugopal, Vivek; Chen, Jin; Barroso, Margarida; Intes, Xavier

    2011-03-01

    We investigate the feasibility of 3-D localization of Foerster resonance energy transfer (FRET) between two NIR fluorophores (Alexa Fluor 700 and Alexa Fluor 750) in small animal models. Specifically, the decrease in donor lifetime upon FRET is used as the contrast mechanism to isolate donor-acceptor pairs undergoing FRET. The optical tomography system uses a femtosecond tunable laser coupled with a micro-mirror device based digital light processor as the source to generate wide-field patterns. The time-resolved detection is achieved using a gated intensified CCD camera. The wide-field excitation scheme described herein provides an experimental advantage by reducing the time of acquisition of temporally dense datasets. In this study, anatomical information obtained using MR imaging is used in the computation of the Monte Carlo (MC) based forward model. The MC model reconstructs the 3D distribution of the quantum yield of the donor fluorophore and the FRET complex using the time-gate data type allowing the estimation of fractional distribution (?D) of donor molecules undergoing FRET and unquenched donor molecules. The performance of this approach in the estimation of ?D using the position of fluorophores obtained using the MRI is investigated.

  13. Should oral implants be splinted in a mandibular implant-supported fixed complete denture? A 3-dimensional-model finite element analysis.

    PubMed

    Alvarez-Arenal, Angel; Brizuela-Velasco, Aritza; DeLlanos-Lanchares, Hector; Gonzalez-Gonzalez, Ignacio

    2014-09-01

    The design of a mandibular fixed complete denture can influence periimplant bone loss. However, the design that transfers the greatest stress to the periimplant bone is not well documented. The purpose of this study was to assess the stress distribution associated with splinted and nonsplinted implant-supported mandibular fixed complete denture designs. Three-dimensional finite element models simulating 6 osseointegrated implants were created in the mandible to support a cobalt-chromium alloy and feldspathic porcelain veneering framework. One model simulated a 1-piece framework, and the other models simulated 2-piece and 3-piece frameworks. Axial and oblique loads were applied to the frameworks. For all the models, the greatest stress values were recorded in the periimplant bone of posterior implants, with differences between the left and right sides. The axial load transferred greater stress values to the periimplant bone than did the oblique load. The lowest periimplant bone stress values were observed in the 3-piece framework model at all implant locations, with the exception of implants placed in the canine region. A framework separated into 3 pieces transfers the least stress to the periimplant bone. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  14. Time-resolved confocal analysis of antibody penetration into living, solid tumor spheroids.

    PubMed

    Myrdal, S; Foster, M

    1994-01-01

    The in vivo function of a biologically active molecule is governed in part by the dynamics of its distribution within its target tissue. To enhance our ability to probe living cells, we have endeavored to improve live confocal microscopy methods and to develop analytical methods that simplify the handling of the resulting complex data sets. To do this we attached a recently developed micro-incubation system to the stage of a Leica confocal laser scanning microscope and were able to maintain physiologic culture conditions over several hours. Axial stability was achieved by modifying the room air conditioning. Laser illumination was low enough to retain cell viability through several hours of continuous scanning. With this setup, planar, time-resolved data sets (xyt) were produced by continuously rescanning a single xy plane at the rate of one scan/min. As an alternative, volumetric data sets (xyz) were acquired by stepping the scanned plane through the z axis. In both types of data sets, a semi-quantitative determination of the concentration of a fluorescent reporter molecule (e.g., FITC) over a gray level range of 0.255 was recorded along with the positional information. Thus, concentration (as intensity of fluorescence, or i) gave a fourth variable by either scan method, resulting in high-density xyti or xyzi data sets. The biological model we used to examine these methods was the penetration of a FITC-labeled, anti-carcinoma monoclonal antibody into cultured spheroids of tumor cells bearing the antibody-binding epitope. In one case, the distribution of antibody-FITC conjugate was compared with that of a long wavelength membrane dye, DiIC18(5). Several different software analyses were compared, including examining xyt data sets as "volumes". We observed that by increasing the displayed resolution of one variable, the demonstrable resolution of the other variables was reduced. For example, with high temporal resolution, either quantitative or positional resolution

  15. A 3-dimensional micro- and nanoparticle transport and filtration model (MNM3D) applied to the migration of carbon-based nanomaterials in porous media

    NASA Astrophysics Data System (ADS)

    Bianco, Carlo; Tosco, Tiziana; Sethi, Rajandrea

    2016-10-01

    Engineered nanoparticles (NPs) in the environment can act both as contaminants, when they are unintentionally released, and as remediation agents when injected on purpose at contaminated sites. In this work two carbon-based NPs are considered, namely CARBO-IRON®, a new material developed for contaminated site remediation, and single layer graphene oxide (SLGO), a potential contaminant of the next future. Understanding and modeling the transport and deposition of such NPs in aquifer systems is a key aspect in both cases, and numerical models capable to simulate NP transport in groundwater in complex 3D scenarios are necessary. To this aim, this work proposes a modeling approach based on modified advection-dispersion-deposition equations accounting for the coupled influence of flow velocity and ionic strength on particle transport. A new modeling tool (MNM3D - Micro and Nanoparticle transport Model in 3D geometries) is presented for the simulation of NPs injection and transport in 3D scenarios. MNM3D is the result of the integration of the numerical code MNMs (Micro and Nanoparticle transport, filtration and clogging Model - Suite) in the well-known transport model RT3D (Clement et al., 1998). The injection in field-like conditions of CARBO-IRON® (20 g/l) amended by CMC (4 g/l) in a 2D vertical tank (0.7 × 1.0 × 0.12 m) was simulated using MNM3D, and compared to experimental results under the same conditions. Column transport tests of SLGO at a concentration (10 mg/l) representative of a possible spill of SLGO-containing waste water were performed at different values of ionic strength (0.1 to 35 mM), evidencing a strong dependence of SLGO transport on IS, and a reversible blocking deposition. The experimental data were fitted using the numerical code MNMs and the ionic strength-dependent transport was up-scaled for a full scale 3D simulation of SLGO release and long-term transport in a heterogeneous aquifer. MNM3D showed to potentially represent a valid tool for

  16. A 3-dimensional micro- and nanoparticle transport and filtration model (MNM3D) applied to the migration of carbon-based nanomaterials in porous media.

    PubMed

    Bianco, Carlo; Tosco, Tiziana; Sethi, Rajandrea

    2016-10-01

    Engineered nanoparticles (NPs) in the environment can act both as contaminants, when they are unintentionally released, and as remediation agents when injected on purpose at contaminated sites. In this work two carbon-based NPs are considered, namely CARBO-IRON®, a new material developed for contaminated site remediation, and single layer graphene oxide (SLGO), a potential contaminant of the next future. Understanding and modeling the transport and deposition of such NPs in aquifer systems is a key aspect in both cases, and numerical models capable to simulate NP transport in groundwater in complex 3D scenarios are necessary. To this aim, this work proposes a modeling approach based on modified advection-dispersion-deposition equations accounting for the coupled influence of flow velocity and ionic strength on particle transport. A new modeling tool (MNM3D - Micro and Nanoparticle transport Model in 3D geometries) is presented for the simulation of NPs injection and transport in 3D scenarios. MNM3D is the result of the integration of the numerical code MNMs (Micro and Nanoparticle transport, filtration and clogging Model - Suite) in the well-known transport model RT3D (Clement et al., 1998). The injection in field-like conditions of CARBO-IRON® (20g/l) amended by CMC (4g/l) in a 2D vertical tank (0.7×1.0×0.12m) was simulated using MNM3D, and compared to experimental results under the same conditions. Column transport tests of SLGO at a concentration (10mg/l) representative of a possible spill of SLGO-containing waste water were performed at different values of ionic strength (0.1 to 35mM), evidencing a strong dependence of SLGO transport on IS, and a reversible blocking deposition. The experimental data were fitted using the numerical code MNMs and the ionic strength-dependent transport was up-scaled for a full scale 3D simulation of SLGO release and long-term transport in a heterogeneous aquifer. MNM3D showed to potentially represent a valid tool for the

  17. Circumstellar Variations and Microflaring in FK Comae Berenices: Time-Resolved Balmer Line Spectroscopy

    NASA Astrophysics Data System (ADS)

    Oliveira, J. M.; Foing, B. H.; Gondoin, Ph.; Stempels, H. C.; Sonnentrucker, P.; Le Poole, R. S.; Ehrenfreund, P.; de Jong, J. A.; Schrijvers, C.; Henrichs, H.; ESA-MUSICOS Collaboration

    We present results from the analysis of spectra of the fast rotating giant FK Comae Berenices, obtained with the recently commissioned ESA-MUSICOS spectrograph at the INT and with the Aurelie spectrograph at the OHP. The Balmer lines broad emission is modelled as arising from structures extending up to 4 stellar radii. The absorption is modelled due to the presence of a shell of cold and dense gas (solar-like filaments), near the corotation radius, covering about 20% of the stellar disc. The extended emission is believed to arise in giant structures reminiscent of active loops or prominences. Time resolved Hα emission spectroscopy indicates that these structures undergo continuous microflaring. Based on data sets from May and November 1996 and May and June 1997, we describe different time scales for variability, from yearly rise of activity to hourly microflares. Based on observations with the ESA-MUSICOS spectrograph at the 2.5 m Isaac Newton Telescope, ING Observatory, Spain and with the Aurelie spectrograph at the 1.52 m Coude Telescope, Observatoire de Haute-Provence, France

  18. Time-resolved electron kinetics in swift heavy ion irradiated solids

    NASA Astrophysics Data System (ADS)

    Medvedev, N. A.; Rymzhanov, R. A.; Volkov, A. E.

    2015-09-01

    The event-by-event Monte Carlo model, TREKIS, was developed to describe the excitation of the electron subsystems of various solids by a penetrating swift heavy ion (SHI), the spatial spreading of generated fast electrons, and secondary electron and hole cascades. Complex dielectric function formalism is used to obtain relevant cross sections. This allows the recognition of fundamental effects resulting from the collective response of the electron subsystem of a target for excitation that is not possible within the binary collision approximation of these cross sections, e.g. the differences in the electronic stopping of an ion and in the electron mean free paths for different structures (phases) of a material. A systematic study performed with this model for different materials (insulators, semiconductors and metals) revealed effects which may be important for an ion track: e.g. the appearance of a second front of excess electronic energy propagation outwards from the track core following the primary front of spreading of generated electrons. We also analyze how the initial ballistic spatial spreading of fast electrons generated in a track turns to the diffusion ~10 fs after ion passage. Detailed time-resolved simulations of electronic subsystem kinetics helped in understanding the reasons behind enhanced silicon resistance to SHI irradiation in contrast to easily produced damage in this material by femtosecond laser pulses. We demonstrate that the fast spreading of excited electrons from the track core on a sub-100 fs timescale prevents the Si lattice from nonthermal melting in a relaxing SHI track.

  19. [Time-resolved optical studies of charge relaxation and charge transfer at electrode interfaces

    SciTech Connect

    Not Available

    1992-01-01

    Key components were identified in a quantitative model of carrier relaxation in semiconductor electrodes: nonlinear aspects of nonradiative and radiative recombination, effect of space charge field on carrier dynamics, self-absorption effects in direct gas semiconductors, and influence of surface state population kinetics on charge carrier recombination. For CdSe, the first three are operative (no direct proof of the last one). A realistic kinetic model for carrier recombination in the bulk of CdSe was used which includes important nonlinear effects, both radiative and nonradiative. The change in interfacial recombination velocity with the chemical nature of the sinterface was studied (n-CdSe/silane interfaces). Temperature effect (278 to 328 K) on fluorescence decay of n-CdSe in contact with 0.5 M KOH was found to be weak. An analytical solution was obtained for time-resolved fluoresence from electrodes under potential bias, and is being tested. Fluorescence work on a different material, CdS, indicate different recombination kinetics; this material was used to directly pump an optical transition of a surface state.

  20. [Time-resolved optical studies of charge relaxation and charge transfer at electrode interfaces

    SciTech Connect

    Not Available

    1992-12-31

    Key components were identified in a quantitative model of carrier relaxation in semiconductor electrodes: nonlinear aspects of nonradiative and radiative recombination, effect of space charge field on carrier dynamics, self-absorption effects in direct gas semiconductors, and influence of surface state population kinetics on charge carrier recombination. For CdSe, the first three are operative (no direct proof of the last one). A realistic kinetic model for carrier recombination in the bulk of CdSe was used which includes important nonlinear effects, both radiative and nonradiative. The change in interfacial recombination velocity with the chemical nature of the sinterface was studied (n-CdSe/silane interfaces). Temperature effect (278 to 328 K) on fluorescence decay of n-CdSe in contact with 0.5 M KOH was found to be weak. An analytical solution was obtained for time-resolved fluoresence from electrodes under potential bias, and is being tested. Fluorescence work on a different material, CdS, indicate different recombination kinetics; this material was used to directly pump an optical transition of a surface state.

  1. Time-resolved imaging of nanosecond-pulsed micro-discharges in heptane

    NASA Astrophysics Data System (ADS)

    Hamdan, A.; Marinov, I.; Rousseau, A.; Belmonte, T.

    2014-02-01

    Nanosecond-pulsed micro-discharges in heptane are studied by time-resolved imaging in pin-to-plate configuration. When a voltage of +5 kV is applied to the pin electrode, the discharge exhibits one maximum in light intensity. At +15 kV, filtered images show that up to three maxima can be identified. These maxima are associated with local electron-ion recombination and bremsstrahlung emission and attributed to the development of a complex space-charge field. In the post-discharge, the dynamics of the gas bubble can be simulated by the Gilmore model, and the pressure evolution in this bubble is predicted. From our results, it seems reasonable to think that the gas bubble develops from the post-discharge of the spark. Results obtained by using the double-pulse technique show that light emission during the post-discharge of the second discharge lasts 10 times longer than the post-discharge of the first spark. The pressure drop in the gas bubble, predicted by the Gilmore model, is used to explain this result and it provides a control method by optical diagnostics in liquids.

  2. Time-resolved microplasma excitation temperature in a pulsed microwave discharge

    NASA Astrophysics Data System (ADS)

    Hopwood, Jeffrey; Monfared, Shabnam; Hoskinson, Alan

    2013-09-01

    Microwave-driven microplasmas are usually operated in a steady-state mode such that the electron temperature is constant in time. Transient measurements of excitation temperature and helium emission lines, however, suggest that short microwave pulses can be used to raise the electron energy by 20-30% for approximately 100 ns. Time-resolved optical emission spectrometry reveals an initial burst of light emission from the igniting microplasma. This emission overshoot is also correlated with a measured increase in excitation temperature. Excimer emission lags atomic emission, however, and does not overshoot. A simple model demonstrates that an increase in electron temperature is responsible for the overshoot of atomic optical emission at the beginning of each microwave pulse. The formation of dimers and subsequent excimer emission requires slower three-body collisions with the excited rare gas atom; this is why excimer emission does not overshoot the steady state value. Similar experimental and modeling results are observed in argon gas. The overshoot in electron temperature may be used to manipulate the collisional production of species in microplasmas using short, low-duty cycle microwave pulses. This material is based upon work supported by the USAF and Physical Sciences Inc., under contract No. FA8650-C-12-C-2312. Additional support was provided by the DARPA MPD program under award FA9550-12-1-0006.

  3. Time-Resolved Chemical Mapping in Light-Emitting Electrochemical Cells.

    PubMed

    Jafari, Mohammad Javad; Liu, Jiang; Engquist, Isak; Ederth, Thomas

    2017-01-25

    An understanding of the doping and ion distributions in light-emitting electrochemical cells (LECs) is required to approach a realistic conduction model which can precisely explain the electrochemical reactions, p-n junction formation, and ion dynamics in the active layer and to provide relevant information about LECs for systematic improvement of function and manufacture. Here, Fourier-transform infrared (FTIR) microscopy is used to monitor anion density profile and polymer structure in situ and for time-resolved mapping of electrochemical doping in an LEC under bias. The results are in very good agreement with the electrochemical doping model with respect to ion redistribution and formation of a dynamic p-n junction in the active layer. We also physically slow ions by decreasing the working temperature and study frozen-junction formation and immobilization of ions in a fixed-junction LEC device by FTIR imaging. The obtained results show irreversibility of the ion redistribution and polymer doping in a fixed-junction device. In addition, we demonstrate that infrared microscopy is a useful tool for in situ characterization of electroactive organic materials.

  4. Kinetic Analysis of Cation Exchange in Birnessite using Time-resolved Synchrotron X-ray Diffraction

    SciTech Connect

    C Lopano; P Heaney; J Bandstra; J Post; S Brantley

    2011-12-31

    In this study, we applied time-resolved synchrotron X-ray diffraction (TRXRD) to develop kinetic models that test a proposed two-stage reaction pathway for cation exchange in birnessite. These represent the first rate equations calculated for cation exchange in layered manganates. Our previous work has shown that the substitution of K, Cs, and Ba for interlayer Na in synthetic triclinic birnessite induces measurable changes in unit-cell parameters. New kinetic modeling of this crystallographic data supports our previously postulated two-stage reaction pathway for cation exchange, and we can correlate the kinetic steps with changes in crystal structure. In addition, the initial rates of cation exchange, R ({angstrom}{sup 3} min{sup -1}), were determined from changes in unit-cell volume to follow these rate laws: R = 1.75[K{sup +}{sub (aq)}]{sup 0.56}, R = 41.1[Cs{sup +}{sub (aq)}]{sup 1.10}, R = 1.15[Ba{sup 2+}{sub (aq)}]{sup 0.50}. Thus, the exchange rates for Na in triclinic birnessite decreased in the order: Cs >> K > Ba. These results are likely a function of hydration energy differences of the cations and the preference of the solution phase for the more readily hydrated cation.

  5. Gradient-based iterative image reconstruction scheme for time-resolved optical tomography

    SciTech Connect

    Hielscher, A.H.; Klose, A.D.; Hanson, K.M.

    1999-03-01

    Currently available tomographic image reconstruction schemes for optical tomography (OT) are mostly based on the limiting assumptions of small perturbations and a priori knowledge of the optical properties of a reference medium. Furthermore, these algorithms usually require the inversion of large, full, ill-conditioned Jacobian matrices. In this work a gradient-based iterative image reconstruction (GIIR) method is presented that promises to overcome current limitations. The code consists of three major parts: (1) A finite-difference, time-resolved, diffusion forward model is used to predict detector readings based on the spatial distribution of optical properties; (2) An objective function that describes the difference between predicted and measured data; (3) An updating method that uses the gradient of the objective function in a line minimization scheme to provide subsequent guesses of the spatial distribution of the optical properties for the forward model. The reconstruction of these properties is completed, once a minimum of this objective function is found. After a presentation of the mathematical background, two- and three-dimensional reconstruction of simple heterogeneous media as well as the clinically relevant example of ventricular bleeding in the brain are discussed. Numerical studies suggest that intraventricular hemorrhages can be detected using the GIIR technique, even in the presence of a heterogeneous background.

  6. Time-resolved fluorescence polarization spectroscopy of visible and near infrared dyes in picosecond dynamics

    NASA Astrophysics Data System (ADS)

    Pu, Yang; Alfano, Robert R.

    2015-03-01

    Near-infrared (NIR) dyes absorb and emit light within the range from 700 to 900 nm have several benefits in biological studies for one- and/or two-photon excitation for deeper penetration of tissues. These molecules undergo vibrational and rotational motion in the relaxation of the excited electronic states, Due to the less than ideal anisotropy behavior of NIR dyes stemming from the fluorophores elongated structures and short fluorescence lifetime in picosecond range, no significant efforts have been made to recognize the theory of these dyes in time-resolved polarization dynamics. In this study, the depolarization of the fluorescence due to emission from rotational deactivation in solution will be measured with the excitation of a linearly polarized femtosecond laser pulse and a streak camera. The theory, experiment and application of the ultrafast fluorescence polarization dynamics and anisotropy are illustrated with examples of two of the most important medical based dyes. One is NIR dye, namely Indocyanine Green (ICG) and is compared with Fluorescein which is in visible range with much longer lifetime. A set of first-order linear differential equations was developed to model fluorescence polarization dynamics of NIR dye in picosecond range. Using this model, the important parameters of ultrafast polarization spectroscopy were identified: risetime, initial time, fluorescence lifetime, and rotation times.

  7. Recombination Dynamics in Thin-film Photovoltaic Materials via Time-resolved Microwave Conductivity.

    PubMed

    Guse, Joanna A; Jones, Timothy W; Danos, Andrew; McCamey, Dane R

    2017-03-06

    A method for investigating recombination dynamics of photo-induced charge carriers in thin film semiconductors, specifically in photovoltaic materials such as organo-lead halide perovskites is presented. The perovskite film thickness and absorption coefficient are initially characterized by profilometry and UV-VIS absorption spectroscopy. Calibration of both laser power and cavity sensitivity is described in detail. A protocol for performing Flash-photolysis Time Resolved Microwave Conductivity (TRMC) experiments, a non-contact method of determining the conductivity of a material, is presented. A process for identifying the real and imaginary components of the complex conductivity by performing TRMC as a function of microwave frequency is given. Charge carrier dynamics are determined under different excitation regimes (including both power and wavelength). Techniques for distinguishing between direct and trap-mediated decay processes are presented and discussed. Results are modelled and interpreted with reference to a general kinetic model of photoinduced charge carriers in a semiconductor. The techniques described are applicable to a wide range of optoelectronic materials, including organic and inorganic photovoltaic materials, nanoparticles, and conducting/semiconducting thin films.

  8. Time-resolved subtraction method for measuring optical properties of turbid media.

    PubMed

    Milej, Daniel; Abdalmalak, Androu; Janusek, Dariusz; Diop, Mamadou; Liebert, Adam; St Lawrence, Keith

    2016-03-01

    Near-infrared spectroscopy is a noninvasive optical method used primarily to monitor tissue oxygenation due to the absorption properties of hemoglobin. Accurate estimation of hemoglobin concentrations and other light absorbers requires techniques that can separate the effect of absorption from the much greater effect of light scattering. One of the most advanced methods is time-resolved near-infrared spectroscopy (TR-NIRS), which measures the absorption and scattering coefficients of a turbid medium by modeling the recorded distribution time of flight of photons. A challenge with TR-NIRS is that it requires accurate characterization of the dispersion caused by the system. In this study, we present a method for circumventing this problem by applying statistical moment analysis to two time-of-flight distributions measured at separated source-detector distances. Simulations based on analytical models and Monte Carlo code, and tissue-mimicking phantoms, were used to demonstrate its accuracy for source-detector distances typically used in neuroimaging applications. The simplicity of the approach is well suited to real-time applications requiring accurate quantification of the optical properties of a turbid medium.

  9. Cardiothoracic Applications of 3-dimensional Printing.

    PubMed

    Giannopoulos, Andreas A; Steigner, Michael L; George, Elizabeth; Barile, Maria; Hunsaker, Andetta R; Rybicki, Frank J; Mitsouras, Dimitris

    2016-09-01

    Medical 3-dimensional (3D) printing is emerging as a clinically relevant imaging tool in directing preoperative and intraoperative planning in many surgical specialties and will therefore likely lead to interdisciplinary collaboration between engineers, radiologists, and surgeons. Data from standard imaging modalities such as computed tomography, magnetic resonance imaging, echocardiography, and rotational angiography can be used to fabricate life-sized models of human anatomy and pathology, as well as patient-specific implants and surgical guides. Cardiovascular 3D-printed models can improve diagnosis and allow for advanced preoperative planning. The majority of applications reported involve congenital heart diseases and valvular and great vessels pathologies. Printed models are suitable for planning both surgical and minimally invasive procedures. Added value has been reported toward improving outcomes, minimizing perioperative risk, and developing new procedures such as transcatheter mitral valve replacements. Similarly, thoracic surgeons are using 3D printing to assess invasion of vital structures by tumors and to assist in diagnosis and treatment of upper and lower airway diseases. Anatomic models enable surgeons to assimilate information more quickly than image review, choose the optimal surgical approach, and achieve surgery in a shorter time. Patient-specific 3D-printed implants are beginning to appear and may have significant impact on cosmetic and life-saving procedures in the future. In summary, cardiothoracic 3D printing is rapidly evolving and may be a potential game-changer for surgeons. The imager who is equipped with the tools to apply this new imaging science to cardiothoracic care is thus ideally positioned to innovate in this new emerging imaging modality.

  10. Time-resolved study of the mechanical response of tissue phantoms to nanosecond laser pulses.

    PubMed

    Pérez-Gutiérrez, Francisco G; Camacho-López, Santiago; Aguilar, Guillermo

    2011-11-01

    We present a time-resolved study of the interaction of nanosecond laser pulses with tissue phantoms. When a laser pulse interacts with a material, optical energy is absorbed by a combination of linear (heat generation and thermoelastic expansion) and nonlinear absorption (expanding plasma), according to both the laser light irradiance and material properties. The objective is to elucidate the contribution of linear and nonlinear optical absorption to bubble formation. Depending on the local temperatures and pressures reached, both interactions may lead to the formation of bubbles. We discuss three experimental approaches: piezoelectric sensors, time-resolved shadowgraphy, and time-resolved interferometry, to follow the formation of bubbles and measure the pressure originated by 6 ns laser pulses interacting with tissue phantoms. We studied the bubble formation and pressure transients for varying linear optical absorption and for radiant exposures above and below threshold for bubble formation. We report a rapid decay (of 2 orders of magnitude) of the laser-induced mechanical pressure measured (by time-resolved shadowgraphy) very close to the irradiation spot and beyond 1 mm from the irradiation site (by the piezoelectric sensor). Through time-resolved interferometry measurements, we determined that bubble formation can occur at marginal temperature increments as low as 3°C.

  11. Time resolved measurement of charged particle distributions at electrodes in rf and pulsed plasma discharges

    NASA Astrophysics Data System (ADS)

    Gahan, David; Scullin, Paul; Dolinaj, Boris; O Sullivan, Donal; Hopkins, Mike

    2011-10-01

    Retarding field energy analyzers (RFEAs) are commonly used to measure the ion energy distribution function (IEDF) in plasma reactors. When deployed on grounded surfaces the RFEA design can be relatively simple due to the absence of large voltages. At biased surfaces the RFEA design is more complex. Filtering techniques need to be implemented to ensure the RFEA floats at the substrate holder potential. In cases where the discharge and/or substrate holder are driven with a pulsed bias the time resolved IEDFs through the pulse cycle are desirable. Time resolved measurements at a pulsed bias surface are more complicated, mainly because of the need to incorporate low pass filters with high input impedance to allow the RFEA to float at the bias potential. Here, we present a summary of the time resolved measurement capabilities of a RFEA in pulsed plasmas. Time resolved energy distributions of charged species are measured at the grounded electrode in capacitively coupled plasmas. The time resolved IEDFs at a biased electrode are also measured. The RFEA body is allowed to float at the bias potential using low pass filters and a novel technique is implemented to allow time resolution of the IEDF during the bias period. Time resolution of 100ns, at frequencies up to 500 kHz is demonstrated.

  12. Time-resolved PIV investigation of flashback in stratified swirl flames of hydrogen-rich fuel

    NASA Astrophysics Data System (ADS)

    Ranjan, Rakesh; Clemens, Noel

    2016-11-01

    Hydrogen is one of the promising alternative fuels to achieve greener power generation. However, susceptibility of flashback in swirl flames of hydrogen-rich fuels acts as a major barrier to its adoption in gas turbine combustors. The current study seeks to understand the flow-flame interaction during the flashback of the hydrogen-rich flame in stratified conditions. Flashback experiments are conducted with a model combustor equipped with an axial swirler and a center-body. Fuel is injected in the main swirl flow via the fuel ports on the swirler vanes. To achieve mean radial stratification, these fuel ports are located at a radial location closer to the outer wall of the mixing tube. Stratification in the flow is assessed by employing Anisole PLIF imaging. Flashback is triggered by a rapid increase in the global equivalence ratio. The upstream propagation of the flame is investigated by employing time-resolved stereoscopic PIV and chemiluminescence imaging. Stratification leads to substantially different flame propagation behavior as well as increased flame surface wrinkling. We gratefully acknowledge the sponsorship by the DOE NETL under Grant DEFC2611-FE0007107.

  13. Optical characterisation of gold films for time-resolved reflectance thermometry measurements

    NASA Astrophysics Data System (ADS)

    Music, Jasmina; White, Thomas G.; Chapman, David J.; Eakins, Daniel E.

    2015-06-01

    The measurement of temperature represents a long-standing challenge within the field of high-pressure science. Recently, a promising time-resolved reflectance thermometry technique employing embedded gold films has been demonstrated. As an active diagnostic, reflectance thermometry is well suited for dynamic experiments generating temperatures below 1000K, where passive diagnostics such as pyrometry become infeasible due to the transient states created. A critical component of the reflectance thermometry technique is a robust optical characterisation of the gold films, decoupling the thermal and pressure contributions. Additionally, the optical properties of gold vary with both sample preparation and thermal history. With a view towards the development of a spatially-resolved reflectance thermometry technique for temperature measurement, we report the optical characterisation of a range of commercially available or deposited thin film gold samples. Reflectance spectroscopy was performed on the gold films as a function of temperature from ambient conditions to 400K, and as a function of pressure using a diamond anvil cell. The experimental data are fitted to a simple phenomenological Drude model paving the way for the calibrated films to be used during future dynamic experiments.

  14. Using Separable Nonnegative Matrix Factorization Techniques for the Analysis of Time-Resolved Raman Spectra

    NASA Astrophysics Data System (ADS)

    Luce, R.; Hildebrandt, P.; Kuhlmann, U.; Liesen, J.

    2016-09-01

    The key challenge of time-resolved Raman spectroscopy is the identification of the constituent species and the analysis of the kinetics of the underlying reaction network. In this work we present an integral approach that allows for determining both the component spectra and the rate constants simultaneously from a series of vibrational spectra. It is based on an algorithm for non-negative matrix factorization which is applied to the experimental data set following a few pre-processing steps. As a prerequisite for physically unambiguous solutions, each component spectrum must include one vibrational band that does not significantly interfere with vibrational bands of other species. The approach is applied to synthetic "experimental" spectra derived from model systems comprising a set of species with component spectra differing with respect to their degree of spectral interferences and signal-to-noise ratios. In each case, the species involved are connected via monomolecular reaction pathways. The potential and limitations of the approach for recovering the respective rate constants and component spectra are discussed.

  15. a Study of the Hydroxycyclohexadienyl Radical Absorption Using Time-Resolved Resonance Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    O'Donnell, Deanna M.; Tripathi, G. N. R.; Brinkmann, Nicole R.

    2009-06-01

    Thus far there has been little understanding of the vibrational spectra, structure and electronic absorption of hydroxycyclohexadienyl radicals in water. They are primary chemical species formed on interaction of radiation with aqueous solutions containing aromatic molecules. We have applied time- resolved resonance Raman (TR-RR) spectroscopy to structurally identify isomers of cyclohexadienyl radicals formed in the pulse radiolysis, using aqueous benzoate solutions as a model system. An early ESR study ((Eiben, K; Fessenden, R.W.; J. Phys. Chem. 1971, 75, 1186-1201) has shown that a mixture of three benzoate hydroxycyclohexadienyl radical isomers: ortho-, meta- and para- are formed upon electron irradiation of N_{2}O saturated benzoate solution. Their collective transient absorption is believed to exhibit a single broad band in the near UV region (λ_{max} = 330 nm, ɛ_{330} = 3800 M^{-1}cm^{-1}). To extract the single isomeric contribution to this collective absorption, we applied TR-RR at various wavelengths within the broad transient absorption range looking for the characteristic indication of each individual isomer. Raman signals of various para-substituted benzoates were also collected to aid in the vibrational studies of the aforementioned benzoate hydroxycyclohexadienyl radicals.

  16. Simultaneous unfolding of compression and opacity from time-resolved radiography

    NASA Astrophysics Data System (ADS)

    Swift, D.; Hawreliak, J.; Rothman, S.; Kritcher, A.; Doeppner, T.; Collins, G.; Gaffney, J.; Rose, S.

    2013-06-01

    Radiographs of symmetric objects can be analyzed to give the spatial variation of attenuation, as in the Abel inversion of an axisymmetric object. If the opacity is known, the mass density can be derived from the attenuation. The space- and time-variation of density is needed to make equation of state (EOS) measurements by radiography, e.g. by measuring the speed and compression of a shock. However, in our experiments using hohlraum drive at the National Ignition Facility (NIF) to perform EOS measurements at gigabar pressures with spherically-converging shocks, the opacity may vary by an order of magnitude because of ionization. We have developed a new algorithm to simultaneously deduce the compression and opacity of the sample given time-resolved radiographs with a Lagrangian location behind the shock, such as the edge of the sample. This approach relies on spatial integration to deduce the opacity in the region just behind the shock from the difference between the known and apparent mass. We assume that the change in opacity is dominated by shock-heating, so that subsequent variations, as shocked material is either released or compressed further, are negligible or can be accounted for by a model. We used this algorithm to analyze our NIF data on the Hugoniot of CH at 10-40 TPa. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  17. Exploiting sparsity in time-of-flight range acquisition using a single time-resolved sensor.

    PubMed

    Kirmani, Ahmed; Colaço, Andrea; Wong, Franco N C; Goyal, Vivek K

    2011-10-24

    Range acquisition systems such as light detection and ranging (LIDAR) and time-of-flight (TOF) cameras operate by measuring the time difference of arrival between a transmitted pulse and the scene reflection. We introduce the design of a range acquisition system for acquiring depth maps of piecewise-planar scenes with high spatial resolution using a single, omnidirectional, time-resolved photodetector and no scanning components. In our experiment, we reconstructed 64 × 64-pixel depth maps of scenes comprising two to four planar shapes using only 205 spatially-patterned, femtosecond illuminations of the scene. The reconstruction uses parametric signal modeling to recover a set of depths present in the scene. Then, a convex optimization that exploits sparsity of the Laplacian of the depth map of a typical scene determines correspondences between spatial positions and depths. In contrast with 2D laser scanning used in LIDAR systems and low-resolution 2D sensor arrays used in TOF cameras, our experiment demonstrates that it is possible to build a non-scanning range acquisition system with high spatial resolution using only a standard, low-cost photodetector and a spatial light modulator.

  18. The time-resolved photoelectron spectrum of toluene using a perturbation theory approach

    SciTech Connect

    Richings, Gareth W.; Worth, Graham A.

    2014-12-28

    A theoretical study of the intra-molecular vibrational-energy redistribution of toluene using time-resolved photo-electron spectra calculated using nuclear quantum dynamics and a simple, two-mode model is presented. Calculations have been carried out using the multi-configuration time-dependent Hartree method, using three levels of approximation for the calculation of the spectra. The first is a full quantum dynamics simulation with a discretisation of the continuum wavefunction of the ejected electron, whilst the second uses first-order perturbation theory to calculate the wavefunction of the ion. Both methods rely on the explicit inclusion of both the pump and probe laser pulses. The third method includes only the pump pulse and generates the photo-electron spectrum by projection of the pumped wavepacket onto the ion potential energy surface, followed by evaluation of the Fourier transform of the autocorrelation function of the subsequently propagated wavepacket. The calculations performed have been used to study the periodic population flow between the 6a and 10b16b modes in the S{sub 1} excited state, and compared to recent experimental data. We obtain results in excellent agreement with the experiment and note the efficiency of the perturbation method.

  19. Modulation of the time-resolved photoluminescence of cadmium selenide by adduct formation with gaseous amines

    SciTech Connect

    Leung, L.K.; Meyer, G.J.; Ellis, A.B. ); Lisensky, G.C. )

    1990-02-22

    The time-resolved, band edge photoluminescence (PL) of cleaved samples of single-crystal n-CdSe has been measured in the presence of N{sub 2}, NH{sub 3}, and CH{sub 3}NH{sub 2} (30% mixtures of the amines in N{sub 2}). Nonexponential decay profiles are modeled. At a low incident average power of {approx} 0.1 mW, both {tau} and {beta} reversibly increase relative to a N{sub 2} ambient upon exposure of CdSe to NH{sub 3} and CH{sub 3}NH{sub 2}, which engage in adduct formation with the semiconductor surface; the magnitude of the enhancement in both decay parameters is larger for the more basic CH{sub 3}NH{sub 2} than for NH{sub 3}. Increases in incident power cause the absolute values of {tau} and {beta} to increase while reducing the dependence of these parameters on gaseous ambient. Interfacial properties that contribute to these effects are discussed and comparisons with steady-state PL properties are presented.

  20. Multiplexed measurements by time resolved spectroscopy using colloidal CdSe/ZnS quantum dots

    NASA Astrophysics Data System (ADS)

    Kaiser, U.; Jimenez de Aberasturi, D.; Malinowski, R.; Amin, F.; Parak, W. J.; Heimbrodt, W.

    2014-01-01

    Multiplexed measurements of analytes in parallel is a topical demand in bioanalysis and bioimaging. An interesting alternative to commonly performed spectral multiplexing is lifetime multiplexing. In this Letter, we present a proof of principle of single-color lifetime multiplexing by coupling the same fluorophore to different nanoparticles. The effective lifetime of the fluorophores can be tuned by more than one order of magnitude due to resonance energy transfer from donor states. Measurements have been done on a model systems consisting of ATTO-590 dye molecules linked to either gold particles or to CdSe/ZnS core shell quantum dots. Both systems show the same luminescence spectrum of ATTO-590 dye emission in continuous wave excitation, but can be distinguished by means of time resolved measurements. The dye molecules bound to gold particles exhibit a mono-exponential decay with a lifetime of 4.5 ns, whereas the dye molecules bound to CdSe/ZnS dots show a nonexponential decay with a slow component of about 135 ns due to the energy transfer from the quantum dots. We demonstrate the fundamental possibility to determine the mixing ratio for dyes with equal luminescence spectra but very different transients. This opens up a pathway independent of the standard optical multiplexing with many different fluorophores emitting from the near ultraviolet to the near infrared spectral region.

  1. Time-resolved detection probe for homogeneous nucleic acid analyses in one-step format.

    PubMed

    Laitala, Ville; Ylikoski, Alice; Raussi, Hanna-Mari; Ollikka, Pia; Hemmilä, Ilkka

    2007-02-01

    We report here an extension of homogeneous assays based on fluorescence intensity and lifetime measuring on DNA hybridization. A novel decay probe that allows simple one-step nucleic acid detection with subnanomolar sensitivity, and is suitable for closed-tube applications, is introduced. The decay probe uses fluorescence resonance energy transfer (FRET) between a europium chelate donor and an organic fluorophore acceptor. The substantial change in the acceptor emission decay time on hybridization with the target sequence allows the direct separation of the hybridized and unhybridized probe populations in a time-resolved measurement. No additional sample manipulation or self-hybridization of the probes is required. The wavelength and decay time of a decay probe can be adjusted according to the selection of probe length and acceptor fluorophore, thereby making the probes applicable to multiplexed assays. Here we demonstrate the decay probe principle and decay probe-based, one-step, dual DNA assay using celiac disease-related target oligonucleotides (single-nucleotide polymorphisms [SNPs]) as model analytes. Decay probes showed specific response for their complementary DNA target and allowed good signal deconvolution based on simultaneous optical and temporal filtering. This technique potentially could be used to further increase the number of simultaneously detected DNA targets in a simple one-step homogeneous assay.

  2. Time Resolved Neutron Reflectivity During Supported Membrane Formation by Vesicle Fusion.

    PubMed

    Koutsioubas, Alexandros; Appavou, Marie-Sousai; Lairez, Didier

    2017-09-05

    The formation of supported lipid bilayers (SLB) on hydrophilic substrates through the method of unilamelar vesicle fusion is used routinely in a wide range of biophysical studies. In an effort to control and better understand the fusion process on the substrate, many experimental studies employing different techniques have been devoted to the elucidation of the fusion mechanism. In the present work we follow the kinetics of membrane formation using time-resolved (TR) neutron reflectivity, focussing at the structural changes near the solid/liquid interface. A clear indication of stacked bilayer structure is observed during the intermediate phase of SLB formation. Adsorbed lipid mass decrease is also measured at the final stage of the process. We have found that it is essential for the analysis of the experimental results to treat theoretically the shape of adsorbed lipid vesicles on an attractive substrate. The overall findings are discussed in relation to proposed fusion mechanisms from previous literature, while we argue that our observations favour a model involving enhanced adhesion of incoming vesicles on the edges of already formed bilayer patches.

  3. Classical description of the dynamics and time-resolved spectroscopy of nonadiabatic cis- trans photoisomerization

    NASA Astrophysics Data System (ADS)

    Uspenskiy, Igor; Strodel, Birgit; Stock, Gerhard

    2006-10-01

    The mapping formulation of nonadiabatic quantum dynamics is applied to obtain a classical description of the ultrafast dynamics and time-resolved spectroscopy of a photochemical reaction. Adopting a previously studied dissipative two-state two-mode model of nonadiabatic cis-trans photoisomerization, classical mapping simulations are compared to quantum-mechanical reduced density matrix calculations. Overall, the simple classical method is found to reproduce the quantum reference calculations quite well. In particular, it is studied if the classical approach yields the correct long-time cis/trans localization of the wave packet and therefore the correct quantum yield of the photoreaction. As the long-time behavior of the classical mapping formulation suffers from the well-known zero point energy problem of classical mechanics, a new practical method is proposed to determine a zero point energy correction. Employing a second-order Franck-Condon-type approximation, the capability of the classical method to simulate time- and frequency-resolved pump-probe spectra of the nonadiabatic photoreaction is studied. The potential of the classical approach as a practical method to describe condensed-phase photoreactions is discussed.

  4. Time-resolved spectroscopy and photometry of the eclipsing AM Herculis binary EXO 033319 - 2554. 2

    SciTech Connect

    Allen, R.G.; Berriman, G.; Smith, P.S.; Schmidt, G.D. )

    1989-12-01

    Time-resolved optical observations of the eclipsing AM Herculis binary EXO 033319 - 2554.2 are presented. High-speed photometry of an eclipse is presented and used to derive a new ephemeris for the system and to estimate the size of the region responsible for the cyclotron emission. Optical spectra that span the orbital cycle are presented, the cyclotron emission in these spectra is discussed, and the flux and radial velocity variations of H-beta, H-gamma, and He II 4686 A are examined. Models of the flux and radial velocity variations of the emission lines indicate that about half the line emission comes from low-velocity material that is about 1.4 x 10 to the 10th cm from the white dwarf. The rest comes from high-velocity material that is about 10 to the 10th cm from the white dwarf and is moving toward it at about 600 km/s. 13 refs.

  5. Multiplexed measurements by time resolved spectroscopy using colloidal CdSe/ZnS quantum dots

    SciTech Connect

    Kaiser, U.; Jimenez de Aberasturi, D.; Malinowski, R.; Amin, F.; Parak, W. J.; Heimbrodt, W.

    2014-01-27

    Multiplexed measurements of analytes in parallel is a topical demand in bioanalysis and bioimaging. An interesting alternative to commonly performed spectral multiplexing is lifetime multiplexing. In this Letter, we present a proof of principle of single-color lifetime multiplexing by coupling the same fluorophore to different nanoparticles. The effective lifetime of the fluorophores can be tuned by more than one order of magnitude due to resonance energy transfer from donor states. Measurements have been done on a model systems consisting of ATTO-590 dye molecules linked to either gold particles or to CdSe/ZnS core shell quantum dots. Both systems show the same luminescence spectrum of ATTO-590 dye emission in continuous wave excitation, but can be distinguished by means of time resolved measurements. The dye molecules bound to gold particles exhibit a mono-exponential decay with a lifetime of 4.5 ns, whereas the dye molecules bound to CdSe/ZnS dots show a nonexponential decay with a slow component of about 135 ns due to the energy transfer from the quantum dots. We demonstrate the fundamental possibility to determine the mixing ratio for dyes with equal luminescence spectra but very different transients. This opens up a pathway independent of the standard optical multiplexing with many different fluorophores emitting from the near ultraviolet to the near infrared spectral region.

  6. Time-resolved microplasma electron dynamics in a pulsed microwave discharge

    NASA Astrophysics Data System (ADS)

    Monfared, S. K.; Hoskinson, A. R.; Hopwood, J.

    2013-10-01

    Microwave-driven microplasmas are typically operated in a steady-state mode in which the electron temperature is constant in time. Transient measurements of excitation temperature and helium emission lines, however, suggest that short microwave pulses can be used to increase the electron energy by 20-30%. Time-resolved optical emission spectrometry reveals an initial burst of light emission from the igniting microplasma. This emission overshoot is also correlated with a measured increase in excitation temperature. Excimer emission lags atomic emission, however, and does not overshoot. A simple model shows that an increase in electron temperature is responsible for the overshoot of atomic optical emission at the beginning of each microwave pulse. The formation of dimers and subsequent excimer emission requires slower three-body collisions with the excited rare gas atoms, which is why excimer emission does not overshoot the steady-state values. Similar results are observed in argon gas. The overshoot in electron temperature may be used to manipulate the collisional production of species in microplasmas using short, low-duty cycle microwave pulses.

  7. pH Dependence of the Photoactive Yellow Protein Photocycle Investigated by Time-Resolved Crystallography

    PubMed Central

    Tripathi, Shailesh; Šrajer, Vukica; Purwar, Namrta; Henning, Robert; Schmidt, Marius

    2012-01-01

    Visualizing the three-dimensional structures of a protein during its biological activity is key to understanding its mechanism. In general, protein structure and function are pH-dependent. Changing the pH provides new insights into the mechanisms that are involved in protein activity. Photoactive yellow protein (PYP) is a signaling protein that serves as an ideal model for time-dependent studies on light-activated proteins. Its photocycle is studied extensively under different pH conditions. However, the structures of the intermediates remain unknown until time-resolved crystallography is employed. With the newest beamline developments, a comprehensive time series of Laue data can now be collected from a single protein crystal. This allows us to vary the pH. Here we present the first structure, to our knowledge, of a short-lived protein-inhibitor complex formed in the pB state of the PYP photocycle at pH 4. A water molecule that is transiently stabilized in the chromophore active site prevents the relaxation of the chromophore back to the trans configuration. As a result, the dark-state recovery is slowed down dramatically. At pH 9, PYP stops cycling through the pB state altogether. The electrostatic environment in the chromophore-binding site is the likely reason for this altered kinetics at different pH values. PMID:22339869

  8. First-principles approach to excitons in time-resolved and angle-resolved photoemission spectra

    NASA Astrophysics Data System (ADS)

    Perfetto, E.; Sangalli, D.; Marini, A.; Stefanucci, G.

    2016-12-01

    In this work we put forward a first-principles approach and propose an accurate diagrammatic approximation to calculate the time-resolved (TR) and angle-resolved photoemission spectrum of systems with excitons. We also derive an alternative formula to the TR photocurrent which involves a single time-integral of the lesser Green's function. The diagrammatic approximation applies to the relaxed regime characterized by the presence of quasistationary excitons and vanishing polarization. The nonequilibrium self-energy diagrams are evaluated using excited Green's functions; since this is not standard, the analytic derivation is presented in detail. The final result is an expression for the lesser Green's function in terms of quantities that can all be calculated in a first-principles manner. The validity of the proposed theory is illustrated in a one-dimensional model system with a direct gap. We discuss possible scenarios and highlight some universal features of the exciton peaks. Our results indicate that the exciton dispersion can be observed in TR and angle-resolved photoemission.

  9. pH Dependence of the Photoactive Yellow Protein Photocycle Investigated by Time-Resolved Crystallography

    SciTech Connect

    Tripathi, Shailesh; Šrajer, Vukica; Purwar, Namrta; Henning, Robert; Schmidt, Marius

    2012-05-24

    Visualizing the three-dimensional structures of a protein during its biological activity is key to understanding its mechanism. In general, protein structure and function are pH-dependent. Changing the pH provides new insights into the mechanisms that are involved in protein activity. Photoactive yellow protein (PYP) is a signaling protein that serves as an ideal model for time-dependent studies on light-activated proteins. Its photocycle is studied extensively under different pH conditions. However, the structures of the intermediates remain unknown until time-resolved crystallography is employed. With the newest beamline developments, a comprehensive time series of Laue data can now be collected from a single protein crystal. This allows us to vary the pH. Here we present the first structure, to our knowledge, of a short-lived protein-inhibitor complex formed in the pB state of the PYP photocycle at pH 4. A water molecule that is transiently stabilized in the chromophore active site prevents the relaxation of the chromophore back to the trans configuration. As a result, the dark-state recovery is slowed down dramatically. At pH 9, PYP stops cycling through the pB state altogether. The electrostatic environment in the chromophore-binding site is the likely reason for this altered kinetics at different pH values.

  10. Homogeneous time-resolved fluorescence quenching assay (LANCE) for caspase-3.

    PubMed

    Karvinen, Jarkko; Hurskainen, Pertti; Gopalakrishnan, Sujatha; Burns, David; Warrior, Usha; Hemmilä, Ilkka

    2002-06-01

    In addition to kinases and G protein-coupled receptors, proteases are one of the main targets in modern drug discovery. Caspases and viral proteases, for instance, are potential targets for new drugs. To satisfy the current need for fast and sensitive high-throughput screening for inhibitors, new homogeneous protease assays are needed. We used a caspase-3 assay as a model to develop a homogeneous time-resolved fluorescence quenching assay technology. The assay utilizes a peptide labeled with both a luminescent europium chelate and a quencher. Cleavage of the peptide by caspase-3 separates the quencher from the chelate and thus recovers europium fluorescence. The sensitivity of the assay was 1 pg/microl for active caspase-3 and 200 pM for the substrate. We evaluated the assay for high-throughput usage by screening 9600 small-molecule compounds. We also evaluated this format for absorption/distribution/metabolism/excretion assays with cell lysates. Additionally, the assay was compared to a commercial fluorescence caspase-3 assay.

  11. In vivo flow cytometry and time-resolved near-IR angiography and lymphography

    NASA Astrophysics Data System (ADS)

    Galanzha, Ekaterina I.; Tuchin, Valery V.; Brock, Robert W.; Zharov, Vladimir P.

    2007-05-01

    Integration of photoacoustic and photothermal techniques with high-speed, high-resolution transmission and fluorescence microscopy shows great potential for in vivo flow cytometry and indocyanine green (ICG) near-infrared (IR) angiography of blood and lymph microvessels. In particular, the capabilities of in vivo flow cytometry using rat mesentery and nude mouse ear models are demonstrated for real-time quantitative detection of circulating and migrating individual blood and cancer cells in skin, mesentery, lymph nodes, liver, kidney; studying vascular dynamics with a focus on lymphatics; monitoring cell traffic between blood and lymph systems; high-speed imaging of cell deformability in flow; and label-free real-time monitoring of single cell extravasation from blood vessel lumen into tissue. As presented, the advantages of ICG IR-angiography include estimation of time resolved dye dynamics (appearance and clearance) in blood and lymph microvessels using fluorescent and photoacoustic modules of the integrated technique. These new approaches are important for monitoring and quantifying metastatic and apoptotic cells; comparative measurements of plasma and cell velocities; analysis of immune responses; monitoring of circulating macromolecules, chylomicrons, bacteria, viruses and nanoparticles; molecular imaging. In the future, we believe that the integrated technique presented will have great potential for translation to early disease diagnoses (e.g. cancer) or assessment of innovative therapeutic interventions in humans.

  12. The time-resolved photoelectron spectrum of toluene using a perturbation theory approach.

    PubMed

    Richings, Gareth W; Worth, Graham A

    2014-12-28

    A theoretical study of the intra-molecular vibrational-energy redistribution of toluene using time-resolved photo-electron spectra calculated using nuclear quantum dynamics and a simple, two-mode model is presented. Calculations have been carried out using the multi-configuration time-dependent Hartree method, using three levels of approximation for the calculation of the spectra. The first is a full quantum dynamics simulation with a discretisation of the continuum wavefunction of the ejected electron, whilst the second uses first-order perturbation theory to calculate the wavefunction of the ion. Both methods rely on the explicit inclusion of both the pump and probe laser pulses. The third method includes only the pump pulse and generates the photo-electron spectrum by projection of the pumped wavepacket onto the ion potential energy surface, followed by evaluation of the Fourier transform of the autocorrelation function of the subsequently propagated wavepacket. The calculations performed have been used to study the periodic population flow between the 6a and 10b16b modes in the S1 excited state, and compared to recent experimental data. We obtain results in excellent agreement with the experiment and note the efficiency of the perturbation method.

  13. Whole-field, time resolved velocity measurements of flow structures on insect wings during free flight

    NASA Astrophysics Data System (ADS)

    Langley, Kenneth; Thomson, Scott; Truscott, Tadd

    2012-11-01

    The development of micro air vehicles (MAVs) that are propelled using flapping flight necessitates an understanding of the unsteady aerodynamics that enable this mode of flight. Flapping flight has been studied using a variety of methods including computational models, experimentation and observation. Until recently, the observation of natural flyers has been limited to qualitative methods such as smoke-line visualization. Advances in imaging technology have enabled the use of particle image velocimetry (PIV) to gain a quantitative understanding of the unsteady nature of the flight. Previously published PIV studies performed on insects have been limited to velocities in a single plane on tethered insects in a wind tunnel. We present the three-dimensional, time-resolved velocity fields of flight around a butterfly, using an array of high-speed cameras at 1 kHz through a technique known as 3D Synthetic Aperture PIV (SAPIV). These results are useful in understanding the relationship between wing kinematics and the unsteady aerodynamics generated.

  14. Nonadiabatic Dynamics May Be Probed through Electronic Coherence in Time-Resolved Photoelectron Spectroscopy.

    PubMed

    Bennett, Kochise; Kowalewski, Markus; Mukamel, Shaul

    2016-02-09

    We present a hierarchy of Fermi golden rules (FGRs) that incorporate strongly coupled electronic/nuclear dynamics in time-resolved photoelectron spectroscopy (TRPES) signals at different levels of theory. Expansion in the joint electronic and nuclear eigenbasis yields the numerically most challenging exact FGR (eFGR). The quasistatic Fermi Golden Rule (qsFGR) neglects nuclear motion during the photoionization process but takes into account electronic coherences as well as populations initially present in the pumped matter as well as those generated internally by coupling between electronic surfaces. The standard semiclassical Fermi Golden Rule (scFGR) neglects the electronic coherences and the nuclear kinetic energy during the ionizing pulse altogether, yielding the classical Condon approximation. The coherence contributions depend on the phase-profile of the ionizing field, allowing coherent control of TRPES signals. The photoelectron spectrum from model systems is simulated using these three levels of theory. The eFGR and the qsFGR show temporal oscillations originating from the electronic or vibrational coherences generated as the nuclear wave packet traverses a conical intersection. These oscillations, which are missed by the scFGR, directly reveal the time-evolving splitting between electronic states of the neutral molecule in the curve-crossing regime.

  15. Time-resolved EUV spectroscopy in the early stage of laser ablation of carbon

    NASA Astrophysics Data System (ADS)

    Loiseleur, Pierre; Hansen, Tue N.; Larour, Jean; Lunney, James G.

    2002-09-01

    In the early stages of laser ablation the combination of high density and optical opacity makes it difficult to use visible spectroscopy for plasma diagnosis. However, these problems can be overcome by working at shorter wavelengths in the EUV. We have used time-resolved EUV emission spectroscopy to study the early stages (1-30 ns) of plasma development in the laser ablation of carbon at an irradiance of 5 GW cm -2. The ablation was done using a 6 ns Nd:YAG laser at 1.06 μm. The spectra were recorded using a grazing incidence spectrometer with a 5 ns-gated micro-channel plate (MCP) detector. An ion probe operating in the time-of-flight mode was used to measure the ion velocity distribution of the plasma outflow. In the 10-35 nm region the predominant line emission was due to Li-like carbon. The temporal variation of the electron density and temperature was deduced by fitting the observed spectrum to a synthetic spectrum calculated using the FLY numerical model of the plasma ionisation and excitation. The temperature deduced from spectroscopy was in good agreement with the estimation from the measured ion velocity distribution in the plasma outflow.

  16. High-Speed Hopping: Time-Resolved Tomographic PIV Measurements of Water Flea Swimming

    NASA Astrophysics Data System (ADS)

    Murphy, D. W.; Webster, D. R.; Yen, J.

    2012-11-01

    Daphniids, also known as water fleas, are small, freshwater crustaceans that live in a low-to-intermediate Reynolds number regime. These plankters are equipped with a pair of branched, setae-bearing antennae that they beat to impulsively propel themselves, or ``hop,'' through the water. A typical hop carries the daphniid one body length forward and is followed by a period of sinking. We present time-resolved tomographic PIV measurements of swimming by Daphnia magna. The body kinematics and flow physics of the daphniid hop are quantified. It is shown that the flow generated by each stroking antenna resembles an asymmetric viscous vortex ring. It is proposed that the flow produced by the daphniid hop can be modeled as a double Stokeslet consisting of two impulsively applied point forces separated by the animal width. The flow physics are discussed in the context of other species operating in the same Reynolds number range of 10 to 100: sea butterfly swimming and flight by the smallest flying insects.

  17. Time-resolved Tomographic PIV Measurements of Water Flea Hopping: Body Size Comparison

    NASA Astrophysics Data System (ADS)

    Skipper, A. N.; Murphy, D. W.; Webster, D. R.; Yen, J.

    2014-11-01

    The flow field of the freshwater crustacean Daphnia magna is quantified with time-resolved tomographic PIV. In the current work, we compare body kinematics and flow disturbance between organisms of small (body length = 1.8 mm) versus medium (2.3 mm) versus large (2.65 mm) size. These plankters are equipped with a pair of antennae that are biramous such that the protopodite splits or branches into an exopodite and an endopodite. They beat the antennae pair synchronously to impulsively propel themselves, or `hop,' through the water. The stroke cycle of Daphnia magna is roughly 80 ms in duration and this period is evenly split between the power and recovery strokes. A typical hop carries the daphniid one body length forward and is followed by a period of sinking. Unlike copepod escape motion, no body vortex is observed in front of the animal. Rather, the flow induced by each antennae consists of a viscous vortex ring that demonstrates a slow decay. The time-record of velocity (peak of 40 mm/s for the medium specimen) and hop acceleration (1.8 m/s2 for the medium specimen) are compared, as well as the strength, size, and decay of the induced viscous vortex rings. The viscous vortex ring analysis will be presented in the context of a double Stokeslet model consisting of two impulsively applied point forces separated by the animal width.

  18. Using Separable Nonnegative Matrix Factorization Techniques for the Analysis of Time-Resolved Raman Spectra.

    PubMed

    Luce, Robert; Hildebrandt, Peter; Kuhlmann, Uwe; Liesen, Jörg

    2016-09-01

    The key challenge of time-resolved Raman spectroscopy is the identification of the constituent species and the analysis of the kinetics of the underlying reaction network. In this work we present an integral approach that allows for determining both the component spectra and the rate constants simultaneously from a series of vibrational spectra. It is based on an algorithm for nonnegative matrix factorization that is applied to the experimental data set following a few pre-processing steps. As a prerequisite for physically unambiguous solutions, each component spectrum must include one vibrational band that does not significantly interfere with the vibrational bands of other species. The approach is applied to synthetic "experimental" spectra derived from model systems comprising a set of species with component spectra differing with respect to their degree of spectral interferences and signal-to-noise ratios. In each case, the species involved are connected via monomolecular reaction pathways. The potential and limitations of the approach for recovering the respective rate constants and component spectra are discussed.

  19. Upregulated expression of La ribonucleoprotein domain family member 6 and collagen type I gene following water-filtered broad-spectrum near-infrared irradiation in a 3-dimensional human epidermal tissue culture model as revealed by microarray analysis.

    PubMed

    Tanaka, Yohei; Nakayama, Jun

    2017-02-27

    Water-filtered broad-spectrum near-infrared irradiation can induce various biological effects, as our previous clinical, histological, and biochemical investigations have shown. However, few studies that examined the changes thus induced in gene expression. The aim was to investigate the changes in gene expression in a 3-dimensional reconstructed epidermal tissue culture exposed to water-filtered broad-spectrum near-infrared irradiation. DNA microarray and quantitative real-time polymerase chain reaction (PCR) analysis was used to assess gene expression levels in a 3-dimensional reconstructed epidermal model composed of normal human epidermal cells exposed to water-filtered broad-spectrum near-infrared irradiation. The water filter allowed 1000-1800 nm wavelengths and excluded 1400-1500 nm wavelengths, and cells were exposed to 5 or 10 rounds of near-infrared irradiation at 10 J/cm(2) . A DNA microarray with over 50 000 different probes showed 18 genes that were upregulated or downregulated by at least twofold after irradiation. Quantitative real-time PCR revealed that, relative to control cells, the gene encoding La ribonucleoprotein domain family member 6 (LARP6), which regulates collagen expression, was significantly and dose-dependently upregulated (P < 0.05) by water-filtered broad-spectrum near-infrared exposure. Gene encoding transcripts of collagen type I were significantly upregulated compared with controls (P < 0.05). This study demonstrates the ability of water-filtered broad-spectrum near-infrared irradiation to stimulate the production of type I collagen. © 2017 The Australasian College of Dermatologists.

  20. Optimization of 3-dimensional imaging of the breast region with 3-dimensional laser scanners.

    PubMed

    Kovacs, Laszlo; Yassouridis, Alexander; Zimmermann, Alexander; Brockmann, Gernot; Wöhnl, Antonia; Blaschke, Matthias; Eder, Maximilian; Schwenzer-Zimmerer, Katja; Rosenberg, Robert; Papadopulos, Nikolaos A; Biemer, Edgar

    2006-03-01

    The anatomic conditions of the female breast require imaging the breast region 3-dimensionally in a normal standing position for quality assurance and for surgery planning or surgery simulation. The goal of this work was to optimize the imaging technology for the mammary region with a 3-dimensional (3D) laser scanner, to evaluate the precision and accuracy of the method, and to allow optimum data reproducibility. Avoiding the influence of biotic factors, such as mobility, we tested the most favorable imaging technology on dummy models for scanner-related factors such as the scanner position in comparison with the torso and the number of scanners and single shots. The influence of different factors of the breast region, such as different breast shapes or premarking of anatomic landmarks, was also first investigated on dummies. The findings from the dummy models were then compared with investigations on test persons, and the accuracy of measurements on the virtual models was compared with a coincidence analysis of the manually measured values. The best precision and accuracy of breast region measurements were achieved when landmarks were marked before taking the shots and when shots at 30 degrees left and 30 degrees right, relative to the sagittal line, were taken with 2 connected scanners mounted with a +10-degree upward angle. However, the precision of the measurements on test persons was significantly lower than those measured on dummies. Our findings show that the correct settings for 3D imaging of the breast region with a laser scanner can achieve an acceptable degree of accuracy and reproducibility.

  1. Carrier-driven disordering in semiconductors: Time-resolved x-ray diffraction and density functional perturbation theory investigations

    NASA Astrophysics Data System (ADS)

    Hillyard, Patrick Brian

    model has been developed for converting the lattice dynamics calculations into predicted diffraction intensities, leading to theoretical verification of the three disordering regimes that were observed experimentally. I have also studied carrier excitation in Cu2O using time-resolved x-ray absorption spectroscopy (XAS) at the Cu L3 edge and the O K edge using ~70 ps x-ray pulses at the Advanced Light Source. After photoexcitation of carriers above the band gap, changes in the XAS spectrum are monitored at 70 ps time delay. By probing the two different atomic sites, changes in the XAS spectrum can be extracted that are both atomic and angular momentum specific. It is observed that the energetic shift in the XAS spectra after photoexcitation of Cu2O is much less than the band gap. The relative change in absorption is observed to be 50% larger at the Cu site than at the O site and there is no integral change in absorption in the transient spectra. The desire to understand the mechanism that underlies chemical, physical and biological transformations motivates the majority of time-resolved studies. While ultrafast laser spectroscopy has greatly enhanced our understanding of dynamical phenomena, many important and interesting processes remain unexplained. Ultrashort pulses of x-rays provide the ability to access atomic and electronic structure with a detail and clarity absent from most optical spectroscopy measurements. It was time-resolved x-ray diffraction using the high per pulse intensity of SPPS that allowed the disordering mechanism in highly excited InSb to be clearly defined in contrast with previous work using optical probes and laser plasma-generated x-ray probes. Furthermore, time-resolved x-ray absorption spectroscopy provided a new experimental tool with which the excited state properties of Cu2O were able to be further elucidated. This dissertation directly shows the significant influence that the introduction of new experimental tools can have on scientific

  2. Recent Advances in 3D Time-Resolved Contrast-Enhanced MR Angiography

    PubMed Central

    Riederer, Stephen J.; Haider, Clifton R.; Borisch, Eric A.; Weavers, Paul T.; Young, Phillip M.

    2015-01-01

    Contrast-enhanced MR angiography (CE-MRA) was first introduced for clinical studies approximately 20 years ago. Early work provided 3 to 4 mm spatial resolution with acquisition times in the 30 sec range. Since that time there has been continuing effort to provide improved spatial resolution with reduced acquisition time, allowing high resolution three-dimensional (3D) time-resolved studies. The purpose of this work is to describe how this has been accomplished. Specific technical enablers have been: improved gradients allowing reduced repetition times, improved k-space sampling and reconstruction methods, parallel acquisition particularly in two directions, and improved and higher count receiver coil arrays. These have collectively made high resolution time-resolved studies readily available for many anatomic regions. Depending on the application, approximate 1 mm isotropic resolution is now possible with frame times of several seconds. Clinical applications of time-resolved CE-MRA are briefly reviewed. PMID:26032598

  3. Recent advances in 3D time-resolved contrast-enhanced MR angiography.

    PubMed

    Riederer, Stephen J; Haider, Clifton R; Borisch, Eric A; Weavers, Paul T; Young, Phillip M

    2015-07-01

    Contrast-enhanced magnetic resonance angiography (CE-MRA) was first introduced for clinical studies approximately 20 years ago. Early work provided 3-4 mm spatial resolution with acquisition times in the 30-second range. Since that time there has been continuing effort to provide improved spatial resolution with reduced acquisition time, allowing high resolution 3D time-resolved studies. The purpose of this work is to describe how this has been accomplished. Specific technical enablers have been: improved gradients allowing reduced repetition times, improved k-space sampling and reconstruction methods, parallel acquisition, particularly in two directions, and improved and higher count receiver coil arrays. These have collectively made high-resolution time-resolved studies readily available for many anatomic regions. Depending on the application, ∼1 mm isotropic resolution is now possible with frame times of several seconds. Clinical applications of time-resolved CE-MRA are briefly reviewed. © 2015 Wiley Periodicals, Inc.

  4. Feasibility experiments on time-resolved fluorosensing applied to oil slicks

    NASA Technical Reports Server (NTRS)

    Camagni, P.; Colombo, G.; Koechler, C.; Pedrini, A.; Omenetto, N.; Rossi, G.

    1986-01-01

    The introduction of time resolved observations can provide a very penetrating tool in the practice of laser fluorosensing. The investigations have demonstrated a relevance of multispectral, time resolved analysis for oil fingerprinting. By comparative studies on a variety of crude oils and their most significant fractions, it was found that the process of time decay in a composite oil is characterized by a few steps, which are associated with specific components in the medium light range. The average decay times of these pure fractions are markedly differentiated as to absolute values and spectral spread; as a consequence, the corresponding parameters in the resultant crude are quite sensitive to the particular mixture of these components. Measurements of the time response give then a finer discrimination between oil classes, depending on the relative content of certain fractions. Experiments were pursued with an improved fluorosensor facility, in order to test the application of time resolved fluorosensing to remote samples on water.

  5. Femtosecond Time-Resolved Resonance-Enhanced CARS of Gaseous Iodine at Room Temperature

    NASA Astrophysics Data System (ADS)

    He, Ping; Fan, Rong-Wei; Xia, Yuan-Qin; Yu, Xin; Yao, Yong; Chen, De-Ying

    2011-04-01

    Time-resolved resonance-enhanced coherent anti-Stokes Raman scattering (CARS) is applied to investigate molecular dynamics in gaseous iodine. 40 fs laser pulses are applied to create and monitor the high vibrational states of iodine at room temperature (corresponding to a vapor pressure as low as about 35 Pa) by femtosecond time-resolved CARS. Depending on the time delay between the probe pulse and the pump/Stokes pulse pairs, the high vibrational states both on the electronically ground states and the excited states can be detected as oscillations in the CARS transient signal. It is proved that the femtosecond time-resolved CARS technique is a promising candidate for investigating the molecular dynamics of a low concentration system and can be applied to environmental and atmospheric monitoring measurements.

  6. The kinetic dose limit in room-temperature time-resolved macromolecular crystallography

    PubMed Central

    Schmidt, M.; Šrajer, V.; Purwar, N.; Tripathi, S.

    2012-01-01

    Protein X-ray structures are determined with ionizing radiation that damages the protein at high X-ray doses. As a result, diffraction patterns deteriorate with the increased absorbed dose. Several strategies such as sample freezing or scavenging of X-ray-generated free radicals are currently employed to minimize this damage. However, little is known about how the absorbed X-ray dose affects time-resolved Laue data collected at physiological temperatures where the protein is fully functional in the crystal, and how the kinetic analysis of such data depends on the absorbed dose. Here, direct evidence for the impact of radiation damage on the function of a protein is presented using time-resolved macromolecular crystallography. The effect of radiation damage on the kinetic analysis of time-resolved X-ray data is also explored. PMID:22338689

  7. The kinetic dose limit in room-temperature time-resolved macromolecular crystallography

    SciTech Connect

    Schmidt, M.; Srajer, V.; Purwar, N.; Tripathi, S.

    2012-05-24

    Protein X-ray structures are determined with ionizing radiation that damages the protein at high X-ray doses. As a result, diffraction patterns deteriorate with the increased absorbed dose. Several strategies such as sample freezing or scavenging of X-ray-generated free radicals are currently employed to minimize this damage. However, little is known about how the absorbed X-ray dose affects time-resolved Laue data collected at physiological temperatures where the protein is fully functional in the crystal, and how the kinetic analysis of such data depends on the absorbed dose. Here, direct evidence for the impact of radiation damage on the function of a protein is presented using time-resolved macromolecular crystallography. The effect of radiation damage on the kinetic analysis of time-resolved X-ray data is also explored.

  8. Apparatus and Techniques for Time-resolved Synchrotron X-ray Diffraction using Diamond Anvil Cells

    NASA Astrophysics Data System (ADS)

    Smith, J.; Sinogeikin, S. V.; Lin, C.; Rod, E.; Bai, L.; Shen, G.

    2015-12-01

    Complementary advances in synchrotron sources, x-ray optics, area detectors, and sample environment control have recently made possible many time-resolved experimental techniques for studying materials at extreme pressure and temperature conditions. The High Pressure Collaborative Access Team (HPCAT) at the Advanced Photon Source has made a sustained effort to assemble a powerful collection of high-pressure apparatus for time-resolved research, and considerable time has been invested in developing techniques for collecting high-quality time-resolved x-ray scattering data. Herein we present key aspects of the synchrotron beamline and ancillary equipment, including source considerations, rapid (de)compression apparatus, high frequency imaging detectors, and software suitable for processing large volumes of data. A number of examples are presented, including fast equation of state measurements, compression rate dependent synthesis of metastable states in silicon and germanium, and ultrahigh compression rates using a piezoelectric driven diamond anvil cell.

  9. Cluster mass fraction and size distribution determined by fs-time-resolved measurements

    NASA Astrophysics Data System (ADS)

    Gao, Xiaohui; Wang, Xiaoming; Shim, Bonggu; Arefiev, Alexey; Tushentsov, Mikhail; Breizman, Boris; Downer, Mike

    2009-11-01

    Characterization of supersonic gas jets is important for accurate interpretation and control of laser-cluster experiments. While average size and total atomic density can be found by standard Rayleigh scatter and interferometry, cluster mass fraction and size distribution are usually difficult to measure. Here we determine the cluster fraction and the size distribution with fs-time-resolved refractive index and absorption measurements in cluster gas jets after ionization and heating by an intense pump pulse. The fs-time-resolved refractive index measured with frequency domain interferometer (FDI) shows different contributions from monomer plasma and cluster plasma in the time domain, enabling us to determine the cluster fraction. The fs-time-resolved absorption measured by a delayed probe shows the contribution from clusters of various sizes, allowing us to find the size distribution.

  10. Time-resolved temperature and O atom measurements in nanosecond pulse discharges in combustible mixtures

    NASA Astrophysics Data System (ADS)

    Lanier, Suzanne; Bowman, Sherrie; Burnette, David; Adamovich, Igor V.; Lempert, Walter R.

    2014-11-01

    The paper presents results of time-resolved rotational temperature measurements, by pure rotational coherent anti-Stokes Raman spectroscopy and absolute O atom number density measurements, by two-photon absorption laser induced fluorescence. The experiments were conducted in nanosecond pulse discharges in H2-O2-Ar and C2H4-O2-Ar mixtures, initially at room temperature, operated at a high pulse repetition rate of 40 kHz, in a plane-to-plane double dielectric barrier geometry at a pressure of 40 Torr. Intensified charge-coupled device images show that O2-Ar and H2-O2-Ar plasmas remain diffuse and volume-filling during the entire burst. Images taken in C2H4-O2-Ar plasma demonstrate significant discharge filamentation and constriction along the center plane and in the corners of the test section. The experimental results demonstrate high accuracy of pure rotational psec CARS for thermometry measurements at low partial pressures of oxygen in nonequilibrium plasmas. The results are compared with kinetic modeling calculations, using two different H2-O2 chemistry and C2H4-O2 chemistry mechanisms. In H2-O2-Ar mixtures, the kinetic modeling predictions are in fairly good agreement with the data, predicting temperature rise and O atom accumulation in long discharge bursts, up to 450 pulses. The results show that adding hydrogen to the mixture results in an additional temperature rise, due to its partial oxidation by radicals generated in the plasma, essentially without chain branching. In C2H4-O2-Ar mixtures, the model consistently underpredicts both temperature and O atom number density. The most likely reason for the difference between the experimental data and model predictions is discharge filamentation developing when ethylene is added to the O2-Ar mixture, at fairly low temperatures.

  11. Time-resolved lasing dynamics for plasmonic system with gain (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Fang, Jieran; Liu, Jingjing; Wang, Zhuoxian; Meng, Xiangeng; Prokopeva, Ludmila J.; Shalaev, Vladimir M.; Kildishev, Alexander V.

    2015-09-01

    To study the light-matter interaction between plasmonic systems and gain media, numerous theoretical and numerical methods have been proposed. Among them, because of its accurate treatment of the quantum property of gain media, the time domain (TD) multi-physics approach is viewed as the most powerful method, especially for analysis of transient dynamics. Even though the finite difference, finite-volume and finite element TD methods can be readily coupled to a multi-level atomic system through auxiliary differential equations, for each of them however there is limited information on accurate TD kinetic parameters fitted with experimental measurements. In this work, we develop a multi-physics time domain model to inspect our most recent lasing experiment with a silver nanohole array. We use a classical finite difference time-domain (FDTD) model coupled to the rate equations of a 4-level gain system. To retrieve kinetic energy parameters for accurate modeling, we first fit 1-D simulations with pump-probe experiments studying Rhodamine-101 (R-101) dye embedded in epoxy on an indium tin oxide silica substrate. The retrieved parameters are then fed into a 3-D model to study the lasing behavior of the R-101-coated nanohole array. The simulated emission intensity shows a clear lasing effect, which is in good agreement with the experimental measurements. By tracing the population inversion and polarization dynamics, the amplification and lasing regimes inside the nanohole cavity can be clearly distinguished. With the help of our systematic approach, we can further improve understanding of the time-resolved physics of active plasmonic nanostructures with gain.

  12. Time-resolved crystallography and protein design: signalling photoreceptors and optogenetics.

    PubMed

    Moffat, Keith

    2014-07-17

    Time-resolved X-ray crystallography and solution scattering have been successfully conducted on proteins on time-scales down to around 100 ps, set by the duration of the hard X-ray pulses emitted by synchrotron sources. The advent of hard X-ray free-electron lasers (FELs), which emit extremely intense, very brief, coherent X-ray pulses, opens the exciting possibility of time-resolved experiments with femtosecond time resolution on macromolecular structure, in both single crystals and solution. The X-ray pulses emitted by an FEL differ greatly in many properties from those emitted by a synchrotron, in ways that at first glance make time-resolved measurements of X-ray scattering with the required accuracy extremely challenging. This opens up several questions which I consider in this brief overview. Are there likely to be chemically and biologically interesting structural changes to be revealed on the femtosecond time-scale? How shall time-resolved experiments best be designed and conducted to exploit the properties of FELs and overcome challenges that they pose? To date, fast time-resolved reactions have been initiated by a brief laser pulse, which obviously requires that the system under study be light-sensitive. Although this is true for proteins of the visual system and for signalling photoreceptors, it is not naturally the case for most interesting biological systems. To generate more biological targets for time-resolved study, can this limitation be overcome by optogenetic, chemical or other means? © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  13. TRIASSIC: the Time-Resolved Industrial Alpha-Source Scanning Induced Current microscope

    NASA Astrophysics Data System (ADS)

    Pallone, Arthur

    Time-resolved ion beam induced current (TRIBIC) microscopy yields useful information such as carrier mobility and lifetimes in semiconductors and defect locations in devices; however, traditional TRIBIC uses large, expensive particle accelerators that require specialized training to operate and maintain. The time-resolved industrial alpha-source scanning induced current (TRIASSIC) microscope transforms TRIBIC by replacing the particle accelerator facility with an affordable, tabletop instrument suitable for use in research and education at smaller colleges and universities. I will discuss the development of, successes with, setbacks to and future directions for TRIASSIC.

  14. Time-resolved resting state fMRI analysis: current status, challenges, and new directions.

    PubMed

    Keilholz, Shella Dawn; Caballero-Gaudes, Cesar; Bandettini, Peter; Deco, Gustavo; Calhoun, Vince D

    2017-09-06

    Time-resolved analysis of resting state fMRI data allows researchers to extract more information about brain function than traditional functional connectivity analysis, yet a number of challenges in data analysis and interpretation remain. This manuscript briefly summarizes common methods for time-resolved analysis and presents some of the pressing issues and opportunities in the field. From there, the discussion moves to the interpretation of the network dynamics observed with resting state fMRI and the role that resting state fMRI can play in elucidating the large-scale organization of brain activity.

  15. A time-resolved infrared vibrational spectroscopic study of the photo-dynamics of crystalline materials.

    PubMed

    Towrie, Mike; Parker, Anthony W; Ronayne, Kate L; Bowes, Katharine F; Cole, Jacqueline M; Raithby, Paul R; Warren, John E

    2009-01-01

    Time-resolved infrared vibrational spectroscopy is a structurally sensitive probe of the excited-state properties of matter. The technique has found many applications in the study of molecules in dilute solution phase but has rarely been applied to crystalline samples. We report on the use of a sensitive pump-probe time-resolved infrared spectrometer and sample handling techniques for studies of the ultrafast excited-state dynamics of crystalline materials. The charge transfer excited states of crystalline metal carbonyls and the proton transfer of dihydroxyquinones are presented and compared with the solution phase.

  16. Luminescent trimethoprim-polyaminocarboxylate lanthanide complex conjugates for selective protein labeling and time-resolved bioassays

    PubMed Central

    Reddy, D. Rajasekhar; Pedró Rosa, Laura E.; Miller, Lawrence W.

    2011-01-01

    Labeling proteins with long-lifetime emitting lanthanide (III) chelate reporters enables sensitive, time-resolved luminescence bioaffinity assays. Heterodimers of trimethoprim (TMP) covalently linked to various cs124-sensitized, polyaminocarboxylate chelates stably retain lanthanide ions and exhibit quantum yields of europium emission up to 20% in water. A time-resolved, luminescence resonance energy transfer (LRET) assay showed that TMP-polyaminocarboxylates bind to Escherichia coli dihydrofolate reductase (eDHFR) fusion proteins with nanomolar affinity in purified solutions and in bacterial lysates. The ability to selectively impart terbium or europium luminescence to fusion proteins in complex physiological mixtures bypasses the need for specific antibodies and simplifies sample preparation. PMID:21619068

  17. Time-resolved principal component imaging analysis of chlorophyll fluorescence induction for monitoring leaf water stress.

    PubMed

    Kobori, Hikaru; Tsuchikawa, Satoru

    2013-06-01

    Chlorophyll fluorescence induction is widely applied to investigate plant growth conditions by calculating the ratio of its intensity at oxidized and reduced states. We examined the applicability of a time-resolved profile of chlorophyll fluorescence induction with the aid of multivariate analysis to monitor the leaf water stress. Principal component (PC) analysis of time-resolved images of chlorophyll fluorescence induction and their score images were reconstructed. Control leaves (non-stressed leaves) and water-stressed leaves could be classified by normalized PC3 score images. This technique has the potential to monitor the water stress condition of plants by using a simple device.

  18. Combined single-pulse holography and time-resolved laser schlieren for flow visualization

    NASA Technical Reports Server (NTRS)

    Burner, A. W.; Goad, W. K.

    1981-01-01

    A pulsed ruby laser and continuous-wave argon ion laser were used in a combined setup at the Langley Expansion Tube for single pulse holography and time resolved laser schlieren with a common optical axis. The systems can be operated simultaneously for a single run. For a single frame, the pulsed holographic setup offers the options of shadowgraph, Schlieren, and interferometry from the reconstructed hologram as well as the advantage of post-run sensitivity adjustments. For flow establishment studies the time resolved laser Schlieren provides visualization of the flow field every 12.5 microns for up to 80 frames with an exposure time per frame of 5.4 microns.

  19. Time resolved resonant photoemission study of energy level alignment at donor/acceptor interfaces

    NASA Astrophysics Data System (ADS)

    Costantini, R.; Pincelli, T.; Cossaro, A.; Verdini, A.; Goldoni, A.; Cichoň, S.; Caputo, M.; Pedio, M.; Panaccione, G.; Silly, M. G.; Sirotti, F.; Morgante, A.; Dell'Angela, M.

    2017-09-01

    The knowledge of the picosecond dynamics of the energy level alignment between donor and acceptor materials in organic photovoltaic devices under working conditions is a challenge for fundamental material research. We measured by means of time-resolved Resonant X-ray Photoemission Spectroscopy (RPES) the energy level alignment in ZnPc/C60 films. We employed 800 nm femtosecond laser pulses to pump the system simulating sunlight excitation and X-rays from the synchrotron as a probe. We measured changes in the valence bands due to pump induced modifications of the interface dipole. Our measurements prove the feasibility of time-resolved RPES with high repetition rate sources.

  20. Combined single-pulse holography and time-resolved laser schlieren for flow visualization

    NASA Astrophysics Data System (ADS)

    Burner, A. W.; Goad, W. K.

    1981-06-01

    A pulsed ruby laser and continuous-wave argon ion laser were used in a combined setup at the Langley Expansion Tube for single pulse holography and time resolved laser schlieren with a common optical axis. The systems can be operated simultaneously for a single run. For a single frame, the pulsed holographic setup offers the options of shadowgraph, Schlieren, and interferometry from the reconstructed hologram as well as the advantage of post-run sensitivity adjustments. For flow establishment studies the time resolved laser Schlieren provides visualization of the flow field every 12.5 microns for up to 80 frames with an exposure time per frame of 5.4 microns.

  1. Electron-hole recombination on ZnO(0001) single-crystal surface studied by time-resolved soft X-ray photoelectron spectroscopy

    SciTech Connect

    Yukawa, R.; Yamamoto, S.; Ogawa, M.; Yamamoto, Sh.; Fujikawa, K.; Hobara, R.; Matsuda, I.; Ozawa, K.; Emori, M.; Sakama, H.; Kitagawa, S.; Daimon, H.

    2014-10-13

    Time-resolved soft X-ray photoelectron spectroscopy (PES) experiments were performed with time scales from picoseconds to nanoseconds to trace relaxation of surface photovoltage on the ZnO(0001) single crystal surface in real time. The band diagram of the surface has been obtained numerically using PES data, showing a depletion layer which extends to 1 μm. Temporal evolution of the photovoltage effect is well explained by a recombination process of a thermionic model, giving the photoexcited carrier lifetime of about 1 ps at the surface under the flat band condition. This lifetime agrees with a temporal range reported by the previous time-resolved optical experiments.

  2. Time Resolved Measurements of the Switching Trajectory of Pt /Co Elements Induced by Spin-Orbit Torques

    NASA Astrophysics Data System (ADS)

    Decker, M. M.; Wörnle, M. S.; Meisinger, A.; Vogel, M.; Körner, H. S.; Shi, G. Y.; Song, C.; Kronseder, M.; Back, C. H.

    2017-06-01

    We report the experimental observation of spin-orbit torque induced switching of perpendicularly magnetized Pt /Co elements in a time resolved stroboscopic experiment based on high resolution Kerr microscopy. Magnetization dynamics is induced by injecting subnanosecond current pulses into the bilayer while simultaneously applying static in-plane magnetic bias fields. Highly reproducible homogeneous switching on time scales of several tens of nanoseconds is observed. Our findings can be corroborated using micromagnetic modeling only when including a fieldlike torque term as well as the Dzyaloshinskii-Moriya interaction mediated by finite temperature.

  3. 3-dimensional imaging at nanometer resolutions

    DOEpatents

    Werner, James H.; Goodwin, Peter M.; Shreve, Andrew P.

    2010-03-09

    An apparatus and method for enabling precise, 3-dimensional, photoactivation localization microscopy (PALM) using selective, two-photon activation of fluorophores in a single z-slice of a sample in cooperation with time-gated imaging for reducing the background radiation from other image planes to levels suitable for single-molecule detection and spatial location, are described.

  4. Signal to noise considerations for single crystal femtosecond time resolved crystallography of the Photoactive Yellow Protein.

    PubMed

    van Thor, Jasper J; Warren, Mark M; Lincoln, Craig N; Chollet, Matthieu; Lemke, Henrik Till; Fritz, David M; Schmidt, Marius; Tenboer, Jason; Ren, Zhong; Srajer, Vukica; Moffat, Keith; Graber, Tim

    2014-01-01

    Femtosecond time resolved pump-probe protein X-ray crystallography requires highly accurate measurements of the photoinduced structure factor amplitude differences. In the case of femtosecond photolysis of single P63 crystals of the Photoactive Yellow Protein, it is shown that photochemical dynamics place a considerable restraint on the achievable time resolution due to the requirement to stretch and add second order dispersion in order to generate threshold concentration levels in the interaction region. Here, we report on using a 'quasi-cw' approach to use the rotation method with monochromatic radiation and 2 eV bandwidth at 9.465 keV at the Linac Coherent Light Source operated in SASE mode. A source of significant Bragg reflection intensity noise is identified from the combination of mode structure and jitter with very small mosaic spread of the crystals and very low convergence of the XFEL source. The accuracy with which the three dimensional reflection is approximated by the 'quasi-cw' rotation method with the pulsed source is modelled from the experimentally collected X-ray pulse intensities together with the measured rocking curves. This model is extended to predict merging statistics for recently demonstrated self seeded mode generated pulse train with improved stability, in addition to extrapolating to single crystal experiments with increased mosaic spread. The results show that the noise level can be adequately modelled in this manner, indicating that the large intensity fluctuations dominate the merged signal-to-noise (I/σI) value. Furthermore, these results predict that using the self seeded mode together with more mosaic crystals, sufficient accuracy may be obtained in order to resolve typical photoinduced structure factor amplitude differences, as taken from representative synchrotron results.

  5. Simulation of multi-photon emission isotopes using time-resolved SimSET multiple photon history generator

    SciTech Connect

    Chiang, Chih-Chieh; Lin, Hsin-Hon; Lin, Chang-Shiun; Chuang, Keh-Shih; Jan, Meei-Ling

    2015-07-01

    Abstract-Multiple-photon emitters, such as In-111 or Se-75, have enormous potential in the field of nuclear medicine imaging. For example, Se-75 can be used to investigate the bile acid malabsorption and measure the bile acid pool loss. The simulation system for emission tomography (SimSET) is a well-known Monte Carlo simulation (MCS) code in nuclear medicine for its high computational efficiency. However, current SimSET cannot simulate these isotopes due to the lack of modeling of complex decay scheme and the time-dependent decay process. To extend the versatility of SimSET for simulation of those multi-photon emission isotopes, a time-resolved multiple photon history generator based on SimSET codes is developed in present study. For developing the time-resolved SimSET (trSimSET) with radionuclide decay process, the new MCS model introduce new features, including decay time information and photon time-of-flight information, into this new code. The half-life of energy states were tabulated from the Evaluated Nuclear Structure Data File (ENSDF) database. The MCS results indicate that the overall percent difference is less than 8.5% for all simulation trials as compared to GATE. To sum up, we demonstrated that time-resolved SimSET multiple photon history generator can have comparable accuracy with GATE and keeping better computational efficiency. The new MCS code is very useful to study the multi-photon imaging of novel isotopes that needs the simulation of lifetime and the time-of-fight measurements. (authors)

  6. Time Resolved Measurement of Ecosystem-Atmosphere NH3 Exchange Using the Eddy Covariance Technique

    NASA Astrophysics Data System (ADS)

    Fischer, M. L.; Littlejohn, D.

    2005-12-01

    Quantifying ammonia fluxes between the land surface and atmosphere is required for effective control of air quality, improving agricultural practices, and understanding natural ecosystem function. Ammonia (NH3) is emitted in large but uncertain amounts from animal agriculture, in lesser amounts from imperfect use of nitrogen fertilizers in crop agriculture, from catalytic converters used on automobiles and other energy related industrial processes, and exchanged between the ecosystem and atmosphere by natural ecosystem processes on vast spatial scales. To address the need for accurate, time-resolved NH3 flux measurements, we have developed an eddy covariance (EC) instrument for direct measurements of NH3 flux. EC flux measurements of NH3 were not previously possible because instruments were not sufficiently sensitive at high frequencies required to capture rapid variations in surface layer NH3 concentrations. To overcome this hurdle we combined a tunable-diode-laser (TDL) spectrometer with a fast-response NH3 sampling inlet and automated pulse-response calibration system. Laboratory tests of the inlet system demonstrate that the response to 10 ppb step in NH3 concentration is well described by a double exponential model with (1/e) times of 0.3 (85% response) and 1.5 (15% response) seconds. This response combined with a routinely measured instrument stability of ~ 0.1 ppb (on 30 minute timescales) indicates that the instrumental contribution to noise in NH3 flux measurements is ~ 0.2 umol NH3 m-2 hr-1, sufficient to stringently test models for NH3 exchange under most conditions. Recent results of field work to verify the instrument performance and observe examples of NH3 exchange will be presented.

  7. Time Resolved Temperature Measurement of Hypervelocity Impact Generated Plasma Using a Global Optimization Method

    NASA Astrophysics Data System (ADS)

    Hew, Y. M.; Linscott, I.; Close, S.

    2015-12-01

    Meteoroids and orbital debris, collectively referred to as hypervelocity impactors, travel between 7 and 72 km/s in free space. Upon their impact onto the spacecraft, the energy conversion from kinetic to ionization/vaporization occurs within a very brief timescale and results in a small and dense expanding plasma with a very strong optical flash. The radio frequency (RF) emission produced by this plasma can potentially lead to electrical anomalies within the spacecraft. In addition, space weather, such as solar activity and background plasma, can establish spacecraft conditions which can exaggerate the damages done by these impacts. During the impact, a very strong impact flash will be generated. Through the studying of this emission spectrum of the impact, we hope to study the impact generated gas cloud/plasma properties. The impact flash emitted from a ground-based hypervelocity impact test is long expected by many scientists to contain the characteristics of the impact generated plasma, such as plasma temperature and density. This paper presents a method for the time-resolved plasma temperature estimation using three-color visible band photometry data with a global pattern search optimization method. The equilibrium temperature of the plasma can be estimated using an optical model which accounts for both the line emission and continuum emission from the plasma. Using a global pattern search based optimizer, the model can isolate the contribution of the continuum emission versus the line emission from the plasma. The plasma temperature can thus be estimated. Prior to the optimization step, a Gaussian process is also applied to extract the optical emission signal out of the noisy background. The resultant temperature and line-to-continuum emission weighting factor are consistent with the spectrum of the impactor material and current literature.

  8. Three-dimensional, Time-Resolved, Intrafraction Motion Monitoring Throughout Stereotactic Liver Radiation Therapy on a Conventional Linear Accelerator

    SciTech Connect

    Worm, Esben S.; Høyer, Morten; Fledelius, Walter; Poulsen, Per R.

    2013-05-01

    Purpose: To investigate the time-resolved 3-dimensional (3D) internal motion throughout stereotactic body radiation therapy (SBRT) of tumors in the liver using standard x-ray imagers of a conventional linear accelerator. Methods and Materials: Ten patients with implanted gold markers received 11 treatment courses of 3-fraction SBRT in a stereotactic body-frame on a conventional linear accelerator. Two pretreatment and 1 posttreatment cone-beam computed tomography (CBCT) scans were acquired during each fraction. The CBCT projection images were used to estimate the internal 3D marker motion during CBCT acquisition with 11-Hz resolution by a monoscopic probability-based method. Throughout the treatment delivery by conformal