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Sample records for photothermal deflection technique

  1. Photothermal deflection spectroscopy and detection

    SciTech Connect

    Jackson, W. B.; Amer, Nabil M.; Boccara, A. C.; Fournier, D.

    1981-04-15

    The theory for a sensitive spectroscopy based on the photothermal deflection of a laser beam is developed. We consider cw and pulsed cases of both transverse and collinear photothermal deflection spectroscopy for solids, liquids, gases, and thin films. The predictions of the theory are experimentally verified, its implications for imaging and microscopy are given, and the sources of noise are analyzed. The sensitivity and versatility of photothermal deflection spectroscopy are compared with thermal lensing and photoacoustic spectroscopy.

  2. On-line monitoring of poly dimethylsiloxane surface modification using the photothermal deflection technique

    NASA Astrophysics Data System (ADS)

    Najmoddin, Najmeh; Khosroshahi, Mohammad. E.

    2015-02-01

    Over the last decade, there has been particular interest in surface modification of biomaterials with regard to understanding the importance of surface characterization. This paper reports the use of photothermal deflection (PTD) technique to monitor modifications in poly dimethylsiloxane (PDMS) surface induced following laser treatments. The FTIR results are in agreement with PTD results, indicating that no structural changes occurred using Argon laser up to 180 s and 200 mW at 454, 488 and 514 nm wavelengths. However, with CO2 laser some physical and chemical changes occurred which are monitored by PTD technique and proved by SEM images.

  3. Optical absorption depth profiling of photodegraded poly(vinylchloride) (PVC) films by quantitative photothermal deflection technique

    NASA Astrophysics Data System (ADS)

    Fu, S.-W.; Power, J. F.; Nepotchatykh, O. V.

    2000-05-01

    An improved photothermal beam deflection technique is applied for optical absorption depth profiling of UV photodegraded PVC films, for nondestructive evaluation of their decomposition mechanism. A new model-based on diffraction theory is used to describe the photothermal response (with bicell recording), induced by impulse irradiation of a depth dependent array of thin planar optical absorbers approximating the sample's depth profile. Improved techniques of alignment, sample preparation and quantitative deconvolution of the bicell impulse response have increased the signal repeatability and reduced the principal bias errors affecting this ill posed problem. By this technique and a stable solution of the inverse problem, the absorption coefficient depth profile is accurately reconstructed in PVC films. Experimental depth profiles were confirmed against destructive techniques run on identical samples of the degraded material. An excellent agreement was found between depth profiles recovered using the mirage effect and these reference methods. Observed absorption profiles were fully consistent with known patterns of depth dependent PVC degradation under nitrogen and oxygen atmospheres.

  4. Photothermal laser deflection, an innovative technique to measure particles in exhausts

    NASA Astrophysics Data System (ADS)

    Hess, Cecil F.

    1993-10-01

    Photothermal Laser Deflection (PLD) is an analytical technique to measure in real-time the mass concentration of particles and gaseous exhaust pollutants in a variety of combustion devices (e.g., gas turbine engines and rockets). PLD uses a pump laser to locally heat the particle or gaseous species, thus changing the refractive index of the surrounding gas to form a thermal lens. A probe laser beam travelling through the thermal lens is temporarily deflected, and the amount of deflection is proportional to the species mass concentration. The experiments and analyses conducted during phase 1 demonstrated the feasibility of PLD in measuring the mass concentration of both soot particles and NO2 at a repetition rate of 25 HZ. PLD response was linear at soot concentrations from 0.3 to 10 mg/cubic meters at NO2 concentrations from approximately 6 to 208 ppm. Strategies to measure lower concentrations have been defined and include focusing the probe beam onto the face of the bi-cell detector. The large dynamic range, fast acquisition rate, and ability to measure particulate and gaseous pollutants makes PLD superior to other available methods.

  5. Thermal analysis of a part of circuit board card by the photothermal deflection technique

    NASA Astrophysics Data System (ADS)

    Dhouib, A.; Yacoubi, N.

    2014-09-01

    Photothermal deflection which is a non-destructive technique is widely used to study defects in materials. However, high spatial resolution and high sensitivity are required to detect them. To validate the theoretical model that we developed in the case, the sample is immersed in a paraffin oil-filled cell and heated with a laser beam of a diameter less than the dimensions of defects and of power 2 mW instead of several 100 mW power frequently used. Our model was tested on a part of a circuit board card having copper strips spaced periodically and embedded in the resin. The experimental curves of amplitude and phase variations according to displacement of the sample are in good agreement with the corresponding theoretical ones; and their coincidence permit us to deduce several parameters such as the width of the copper and resin strips, their thicknesses and their thermal properties. These comparisons allowed also to detect some anomalies in the structure such as inhomogeneity in the width, the shape and the thicknesses of copper and resins strips.

  6. Non-destructive Evaluation of Compound Semiconductor Thin-Film Solar Cells by Photothermal Beam Deflection Technique

    NASA Astrophysics Data System (ADS)

    Warrier, Anita R.; Sebastian, Tina; Kartha, C. Sudha; Vijayakumar, K. P.

    2015-01-01

    In this paper, it is demonstrated that the photothermal beam deflection technique can be used for measuring the series resistance, optimum load resistance, and conversion efficiency of thin-film solar cells. This technique is also used for determining the carrier transport properties of an absorber and window layer of -based solar cells during different stages of cell fabrication. Transport properties such as the carrier mobility, lifetime, and surface recombination velocity of the individual absorber and window layer are shown to influence the open-circuit voltage and short-circuit current of the final photovoltaic device. The cell parameters measured using the photothermal technique agree well with the electrical measurements. The principle of the technique is explained on the basis of the "mirage effect" and maximum power transfer theorem.

  7. Measurement of absolute minority species concentration and temperature in a flame by the photothermal deflection spectroscopy technique.

    PubMed

    Li, Yunjing; Gupta, Rajendra

    2003-04-20

    It is experimentally demonstrated that absolute concentrations of minority species in flames can be measured by the photothermal deflection spectroscopy (PTDS) technique. In addition, the PTDS signal simultaneously yields the flame temperature the measurement point. Absolute concentration profiles of OH have been measured in a flat-flame burner with methane as fuel. The PTDS measurements agree well with those obtained independently by the absorption technique. The flame temperature measurements by PTDS are also in good agreement with those obtained by the Boltzmann distribution among the rotational levels of OH. PMID:12716166

  8. Trace Explosive Detection using Photothermal Deflection Spectroscopy

    SciTech Connect

    Krause, Adam R; Van Neste, Charles W; Senesac, Larry R; Thundat, Thomas George; Finot, Eric

    2008-01-01

    Satisfying the conditions of high sensitivity and high selectivity using portable sensors that are also reversible is a challenge. Miniature sensors such as microcantilevers offer high sensitivity but suffer from poor selectivity due to the lack of sufficiently selective receptors. Although many of the mass deployable spectroscopic techniques provide high selectivity, they do not have high sensitivity. Here, we show that this challenge can be overcome by combining photothermal spectroscopy on a bimaterial microcantilever with the mass induced change in the cantilever's resonance frequency. Detection using adsorption-induced resonant frequency shift together with photothermal deflection spectroscopy shows extremely high selectivity with a subnanogram limit of detection for vapor phase adsorbed explosives, such as pentaerythritol tetranitrate (PETN), cyclotrimethylene trinitramine (RDX), and trinitrotoluene (TNT).

  9. Photothermal deflection spectroscopy investigations of uranium electrochemistry

    SciTech Connect

    Rudnicki, J.D.; Russo, R.E.

    1993-12-31

    Photothermal Deflection Spectroscopy (PDS) has been successfully applied successfully applied to the study of uranium oxide electrochemistry. A brief description of PDS and preliminary results that demonstrate the technique are presented. Concentration gradients formed at the electrode surface are measured by this technique. The gradients give insight into the reaction mechanisms. There is some evidence of the initiation of non-electrochemical dissolution of the uranium oxide. Optical absorption by the uranium oxide is measured by PDS and the first results indicate that the absorption of the surface does not change during electrochemical experiments. This result is contrary to literature measurements of bulk samples that indicate that the optical absorption should be strongly changing.

  10. Transverse photothermal beam deflection within a solid

    SciTech Connect

    Spear, J.D.; Russo, R.E. )

    1991-07-15

    The mirage effect within a transparent solid substrate was used for monitoring optical absorption of a thin film. Refractive index gradients, which accompany thermal gradients below the film-coated surface, cause a probe laser beam to be deflected. The spectrum of copper, deposited onto a piece of clear acrylic, was recorded by this method of photothermal deflection. The influence of thermally induced mechanical stresses can alter the effective value of the thermo-optic coefficient of the solid, {ital dn}/{ital dT}.

  11. Photothermal deflection in a supercritical fluid

    NASA Astrophysics Data System (ADS)

    Briggs, Matthew E.; Gammon, Robert W.

    1994-11-01

    The total losses due to absorption and scatter from the best optical coatings can be made as low as techniques. We show by measurement and calculation that a dramatic increase in the sensitivity of absorption measurements is obtained by using a supercritical fluid, instead of an ordinary (non-critical) fluid, as the sensing fluid in a collinear photothermal-deflection apparatus. The noise floor in our surface-absorption measurements using supercritical xenon, Tc equals 16.7 degree(s)C, corresponds to an absorptance A equals Pabsorbed/Pincident equals 10-10 under illumination of 1 W. Bulk absorption measurements are similarly enhanced: the noise floor corresponds to an absorption coefficient of (alpha) equals 10-13 cm-1 for 1 W of illumination in a sample of length 1 cm. These levels are three orders of magnitude more sensitive than any previously reported. The enhancement is brought about by the divergence in the coefficient of thermal expansion of a fluid near the critical point. In attempting to use this sensitivity to measure the absorption in transmission of low-absorbing (

  12. Application of complex geometrical optics to determination of thermal, transport, and optical parameters of thin films by the photothermal beam deflection technique.

    PubMed

    Korte, Dorota; Franko, Mladen

    2015-01-01

    In this work, complex geometrical optics is, for what we believe is the first time, applied instead of geometrical or wave optics to describe the probe beam interaction with the field of the thermal wave in photothermal beam deflection (photothermal deflection spectroscopy) experiments on thin films. On the basis of this approach the thermal (thermal diffusivity and conductivity), optical (energy band gap), and transport (carrier lifetime) parameters of the semiconductor thin films (pure TiO2, N- and C-doped TiO2, or TiO2/SiO2 composites deposited on a glass or aluminum support) were determined with better accuracy and simultaneously during one measurement. The results are in good agreement with results obtained by the use of other methods and reported in the literature. PMID:26366490

  13. Application of photothermal deflection spectroscopy to electrochemical interfaces

    SciTech Connect

    Rudnicki, J.D.; McLarnon, F.R.; Cairns, E.J.

    1992-03-01

    This dissertation discusses the theory and practice of Photothermal Deflection Spectroscopy (PDS, which is also known as probe beam deflection spectroscopy, PBDS, probe deflection technique, and mirage effect spectroscopy) with respect to electrochemical systems. Much of the discussion is also relevant to non-electrochemical systems. PDS can measure the optical absorption spectrum of interfaces and concentration gradients in the electrolyte adjacent to the electrode. These measurements can be made on a wide variety of electrode surfaces and can be performed under dynamic conditions. The first three chapters discuss the theory of the phenomena that can be detected by PDS, and the equipment used in a PDS system. A secondary gradient technique'' is proposed, which places the probe beam on the back of an electrode. The results of a numerical model yield a method for determining the offset of the probe beam from the electrode surface based on the frequency response of the PDS signal. The origin and control of noise in the PDS signal are discussed. A majority of the signal noise appears to be acoustic in origin. The electrochemical oxidation of platinum is used to demonstrate that PDS has sub-monolayer sensitivity necessary to study interfacial chemistry. The results allow us to propose a two-reaction oxidation mechanism: the platinum is electrochemically oxidized to form platinum dihydroxide and dehydrated by a non-electrochemical second-order reaction. The final chapter discusses the relation of PDS to similar and competing techniques, and considers possibilities for the future of the technique.

  14. Application of photothermal deflection spectroscopy to electrochemical interfaces

    SciTech Connect

    Rudnicki, J.D.; McLarnon, F.R.; Cairns, E.J.

    1992-03-01

    This dissertation discusses the theory and practice of Photothermal Deflection Spectroscopy (PDS, which is also known as probe beam deflection spectroscopy, PBDS, probe deflection technique, and mirage effect spectroscopy) with respect to electrochemical systems. Much of the discussion is also relevant to non-electrochemical systems. PDS can measure the optical absorption spectrum of interfaces and concentration gradients in the electrolyte adjacent to the electrode. These measurements can be made on a wide variety of electrode surfaces and can be performed under dynamic conditions. The first three chapters discuss the theory of the phenomena that can be detected by PDS, and the equipment used in a PDS system. A ``secondary gradient technique`` is proposed, which places the probe beam on the back of an electrode. The results of a numerical model yield a method for determining the offset of the probe beam from the electrode surface based on the frequency response of the PDS signal. The origin and control of noise in the PDS signal are discussed. A majority of the signal noise appears to be acoustic in origin. The electrochemical oxidation of platinum is used to demonstrate that PDS has sub-monolayer sensitivity necessary to study interfacial chemistry. The results allow us to propose a two-reaction oxidation mechanism: the platinum is electrochemically oxidized to form platinum dihydroxide and dehydrated by a non-electrochemical second-order reaction. The final chapter discusses the relation of PDS to similar and competing techniques, and considers possibilities for the future of the technique.

  15. Pulsed photothermal deflection and diffraction effects: numerical modeling based on Fresnel diffraction theory

    NASA Astrophysics Data System (ADS)

    Han, Yue; Wu, Z. L.; Rosenshein, Joseph S.; Thomsen, Marshall; Zhao, Qiang; Moncur, Kent

    1999-12-01

    We present a comprehensive theoretical model suitable for treating the effect of pulsed collinear photothermal deflection spectroscopy (PDS). The work is an extension of the theoretical model previously developed for the mirage effect, which can take into account both photothermal deflection and photothermal diffraction effects based on the Fresnel diffraction theory. With the diffraction model, both the collinear PDS and the photothermal lensing spectroscopy techniques can be treated in a unified manner. The model provides a detailed analysis of the laser-induced optical diffraction effect and can be used to optimize experimental parameters. The modeled results are presented in detail, with an emphasis on the advantages of using a near-field detection scheme for achieving the best sensitivity to local temperature change and better experimental stability against environmental noise.

  16. Photothermal cantilever deflection spectroscopy of a photosensitive polymer

    SciTech Connect

    Yun, Minhyuk; Lee, Dongkyu; Jung, Namchul; Jeon, Sangmin; Kim, Seonghwan; Chae, Inseok; Thundat, Thomas

    2012-05-14

    The mechanical and chemical information of a poly(methyl methacrylate) (PMMA) film on a microcantilever were simultaneously acquired by photothermal cantilever deflection spectroscopy as a function of ultraviolet (UV) irradiation time. Nanomechanical infrared (IR) spectra from the PMMA-coated microcantilever agreed well with the Fourier transform infrared spectroscopy (FTIR) spectra of PMMA on gold-coated silicon wafer. The decreasing intensities of nanomechanical IR peaks represent chemical as well as mechanical information of UV radiation-induced photodegradation processes in the PMMA which cannot be obtained by a conventional FTIR technique. The observed decrease in the resonance frequency of the microcantilever is related to the change in the Young's modulus of the PMMA under UV exposure.

  17. A 3-dimensional time-resolved photothermal deflection ``Mirage'' method

    NASA Astrophysics Data System (ADS)

    Astrath, N. G. C.; Malacarne, L. C.; Lukasievicz, G. V. B.; Bernabe, H. S.; Rohling, J. H.; Baesso, M. L.; Shen, J.; Bialkowski, S. E.

    2012-02-01

    A three-dimensional time-resolved theory and experiment for photothermal deflection spectroscopy is developed. The heat conduction equations for two semi-infinite media consisting of an opaque sample and a fluid are solved considering temperature and energy flux balance conditions for a Gaussian heat source. The time dependent perpendicular deflection signal is calculated and compared to experimental measurements on glassy carbon and copper samples. Excellent agreement with literature values for thermal diffusivity of the samples is found. The transient behavior is analyzed for different coupling fluids.

  18. Pulsed photothermal deflection spectroscopy in fluid media - A review

    NASA Astrophysics Data System (ADS)

    Gupta, R.

    The fundamental principles, apparatus, and applications of photothermal deflection spectroscopy (PTDS) using pulsed lasers are examined, summarizing the results of recent theoretical and experimental investigations. The governing equations are presented and discussed, and diagrams, drawings, and graphs of typical results are provided. In one set of PTDS experiments, a flashlamp-pumped dye laser producing 1-microsec pulses of energy 2 mJ is used to pump NO2 molecules in an open N2 jet or a closed cell containing N2, and the deflection of an 800-microW HeNe laser probe beam by the pump-induced refractive-index changes is measured. The PTDS method permits determination of majority and minority species concentrations, relaxation rates, and temperature, as well as flow velocity in the case of a jet or flame.

  19. Photothermal beam deflection applied to SO2 trace detection

    NASA Astrophysics Data System (ADS)

    Manzano, Francisco A.; D'Accurso, V.; Radulovich, O.

    2004-10-01

    We present the application to environmental monitoring of a compact setup for in situ trace gas detection based on photothermal beam deflection (mirage effect) spectroscopy. Gas traces measurements are performed by detecting the time-varying component of the photothermal deflection of a red diode laser beam, propagating inside the region where a pollutant is excited by another laser. In this work, detection of traces of SO2 in a mixture with Nitrogen at atmospheric pressure enclosed in a glass cell, was performed using the fourth-harmonic pulses of a 10 Hz Nd:YAG laser. It was verified by FTIR spectroscopy that negligible SO2 destruction was produced after irradiation of high pressure mixtures with 105 UV pulses. Several beam sizes and propagating angles for the UV and visible laser were tested and evaluated in order to overcome parasitic signals due to unwanted absorption in optical elements. With this setup we reached a detection limit of 5 ppbV in a hundred-second averaging time span but we estimate sub-ppbV levels can be reached by simple changes in the geometry for improving the signal to noise ratio.

  20. Spatially-resolved investigation of transport in semiconductors: a photothermal deflection approach

    SciTech Connect

    Skumanich, A.; Fournier, D.; Boccara, A.C.; Amer, N.M.

    1985-06-01

    The unique ability of photothermal deflection spectroscopy to probe the local index of refraction of matter is exploited to investigate, in a spatially-resolved manner, thermal and electronic transport in semiconductors. An added advantage of this approach is that it is contactless; hence, it obviates the classical problems associated with electrodes and contacts. The basic premise of the technique is the use of the heat associated with non-radiative processes (e.g., recombination of carriers) to deflect a focussed laser probe beam (sub-gap energy) propagating through the semiconductor. The deflection of the probe beam is caused by a change in the refractive index of the sample which is in turn governed by carrier diffusion and recombination.

  1. Photothermal detection of trace compounds in water, using the deflection of a water meniscus

    NASA Astrophysics Data System (ADS)

    Hodgkinson, Jane; Johnson, Mark; Dakin, John P.

    1998-08-01

    A novel photothermal detector is described, based on a closed cell suitable for use with low-frequency modulated continuous-wave light sources. Photothermal expansion in aqueous samples caused the deflection of a water meniscus held across a 0957-0233/9/8/026/img7 radius pinhole. Displacement of the water meniscus was measured using fibre-optic interferometry. A mercury discharge lamp (254 nm) and a laser diode (678 nm) were used to detect absorption by 2 ppb anthracene and 0.5 ppm potassium permanganate in aqueous solutions, respectively. The technique was used to detect differences between absorption coefficients in aqueous solutions down to approximately 20% of the background absorption of the water itself.

  2. A composite photothermal technique for the measurement of thermal properties of solids

    NASA Astrophysics Data System (ADS)

    Astrath, F. B. G.; Astrath, N. G. C.; Shen, J.; Zhou, J.; Baesso, M. L.

    2008-09-01

    In this work, a composite photothermal technique combining open photoacoustic cell and photothermal deflection methods for thermal characterization of opaque solids was developed. An excitation laser was employed to concurrently generate both photoacoustic and mirage effects. Thermal diffusivity and thermal effusivity of carbon-based samples were measured, and the values of thermal conductivities and specific heat were then deduced. The experimental results were found to be in good agreement with the literature values. The photothermal technique developed in this work permits a convenient and precise measurement of thermal properties of solids.

  3. Device for characterization of thermal effusivity of liquids using photothermal beam deflection.

    PubMed

    Sandoval-Romero, G E; García-Valenzuela, A; Sánchez-Pérez, C; Hernández-Cordero, J; Muratikov, Kyrill L

    2007-10-01

    We propose and study a novel optoelectronic device for thermal characterization of materials. It is based on monitoring the photothermal deflection of a laser beam within a slab of a thermo-optic material in thermal contact with the sample under study. An optical angle sensor is used to measure the laser deflection providing a simple and experimental arrangement. We demonstrate its principle and a simple procedure to measure thermal effusivity of liquids. The proposed device could be implemented into a compact sensor head for remote measurements using electrical and fiber optic links. PMID:17979448

  4. A systematic analysis of the influence of the surrounding media in the photothermal beam deflection signal

    NASA Astrophysics Data System (ADS)

    Gören, A.; Prior, P.; Macedo, F.

    2010-03-01

    The photothermal beam deflection (PDS) technique was tested for low thermal diffusivity materials. The effect of using different liquids as surrounding media was studied in a systematic way. The fundamental experimental parameters, like the pump beam power and the modulation frequency were also studied in order to find out the best combination that still allows us to get good signals. Due to the complexity of the optical alignment required, the usual mirage setup was adapted in order to allow the decoupling of the alignment of the cell containing the liquid and the sample holder. Simple, straightforward methods (like e.g. the phase method) were used for the thermal diffusivity determination of solids once the thermal diffusivity of the liquids used is always much lower than that of solids. The obtained values for the thermal diffusivity of test samples allow us to conclude that besides being possible to use any of the studied liquids as surrounding medium, ethanol is clearly the best choice, avoiding health problems related to CCl4, which is the standard choice for PDS and PDS spectroscopy experiments, and technical/physical problems related to water and acetone. Modulation frequencies around 8 Hz combined with a pump beam power below 15 mW were proved to be the ideal conditions for this kind of experiment. The very low pump beam power required is also an important issue when talking about non-destructive analysis.

  5. Velocimetry in laminar and turbulent flows using the photothermal deflection effect with a transient grating.

    PubMed

    Dasch, C J; Sell, J A

    1986-10-01

    An enhanced-precision, high-signal method for velocity measurements with photothermal deflection spectroscopy is presented. A transient refractive-index grating is formed by the interference of two pulsed, pump-laser beams in an absorbing gas. The motion of the grating is detected by the oscillatory deflection of a probe beam, which has a diameter smaller than the fringe spacing. This two-beam pump improves on single-beam pumps because there are more markers for the velocity determination, and the larger thermal gradients increase the probe deflection. The method is illustrated by velocity maps in a laminar ethylene/nitrogen jet using a CO(2) pump laser. Velocity distributions and noise levels were also measured with grid-induced turbulence above the jet. PMID:19738701

  6. Continuous-wave photothermal deflection spectroscopy with fundamental and harmonic responses

    NASA Astrophysics Data System (ADS)

    Zhao, Jianhua; Shen, Jun; Hu, Cheng

    2002-10-01

    A diffraction theory of continuous-wave photothermal deflection (PD) spectroscopy with fundamental and harmonic responses is presented. The displacement of the probe beam centroid is found to be a rigorous measurement of PD effect, which leads to a set of analytical solutions to the fundamental and the second-order harmonics. Harmonics are caused by the diffraction of the probe beam in the mirage region, which could not be handled by geometric-optics theory. This theory can be used to study bulk materials, thin films, and layered-structure samples. Experimental results are in good agreement with the theory.

  7. Clustering mechanism of ethanol-water mixtures investigated with photothermal microfluidic cantilever deflection spectroscopy.

    PubMed

    Ghoraishi, M S; Hawk, J E; Phani, Arindam; Khan, M F; Thundat, T

    2016-01-01

    The infrared-active (IR) vibrational mode of ethanol (EtOH) associated with the asymmetrical stretching of the C-C-O bond in pico-liter volumes of EtOH-water binary mixtures is calorimetrically measured using photothermal microfluidic cantilever deflection spectroscopy (PMCDS). IR absorption by the confined liquid results in wavelength dependent cantilever deflections, thus providing a complementary response to IR absorption revealing a complex dipole moment dependence on mixture concentration. Solvent-induced blue shifts of the C-C-O asymmetric vibrational stretch for both anti and gauche conformers of EtOH were precisely monitored for EtOH concentrations ranging from 20-100% w/w. Variations in IR absorption peak maxima show an inverse dependence on induced EtOH dipole moment (μ) and is attributed to the complex clustering mechanism of EtOH-water mixtures. PMID:27046089

  8. Clustering mechanism of ethanol-water mixtures investigated with photothermal microfluidic cantilever deflection spectroscopy

    NASA Astrophysics Data System (ADS)

    Ghoraishi, M. S.; Hawk, J. E.; Phani, Arindam; Khan, M. F.; Thundat, T.

    2016-04-01

    The infrared-active (IR) vibrational mode of ethanol (EtOH) associated with the asymmetrical stretching of the C-C-O bond in pico-liter volumes of EtOH-water binary mixtures is calorimetrically measured using photothermal microfluidic cantilever deflection spectroscopy (PMCDS). IR absorption by the confined liquid results in wavelength dependent cantilever deflections, thus providing a complementary response to IR absorption revealing a complex dipole moment dependence on mixture concentration. Solvent-induced blue shifts of the C-C-O asymmetric vibrational stretch for both anti and gauche conformers of EtOH were precisely monitored for EtOH concentrations ranging from 20–100% w/w. Variations in IR absorption peak maxima show an inverse dependence on induced EtOH dipole moment (μ) and is attributed to the complex clustering mechanism of EtOH-water mixtures.

  9. Clustering mechanism of ethanol-water mixtures investigated with photothermal microfluidic cantilever deflection spectroscopy

    PubMed Central

    Ghoraishi, M. S.; Hawk, J. E.; Phani, Arindam; Khan, M. F.; Thundat, T.

    2016-01-01

    The infrared-active (IR) vibrational mode of ethanol (EtOH) associated with the asymmetrical stretching of the C-C-O bond in pico-liter volumes of EtOH-water binary mixtures is calorimetrically measured using photothermal microfluidic cantilever deflection spectroscopy (PMCDS). IR absorption by the confined liquid results in wavelength dependent cantilever deflections, thus providing a complementary response to IR absorption revealing a complex dipole moment dependence on mixture concentration. Solvent-induced blue shifts of the C-C-O asymmetric vibrational stretch for both anti and gauche conformers of EtOH were precisely monitored for EtOH concentrations ranging from 20–100% w/w. Variations in IR absorption peak maxima show an inverse dependence on induced EtOH dipole moment (μ) and is attributed to the complex clustering mechanism of EtOH-water mixtures. PMID:27046089

  10. Study of saturated triglycerides in oil based on the c.w. transverse CO 2 laser excited photothermal deflection signals

    NASA Astrophysics Data System (ADS)

    Bicanic, Dane; Franko, Mladen; Jalink, Henk; Dukić, Rasto; Bozóki, Zoltán; Linssen, Jozef

    1995-02-01

    A photothermal beam deflection spectrometer comprising a novel sample cell, CO 2 laser (pump source) and a diode laser (probe beam) in a transverse (crossed) configuration was constructed and used to study triglycerides in diet oil. Prospects of this method for trace detection are evaluated and compared to the results expected from the collinear geometry with focused pump and probe beams.

  11. Sub-gap and band edge optical absorption in a-Si:H by photothermal deflection spectroscopy

    NASA Astrophysics Data System (ADS)

    Jackson, W. B.; Amer, N. M.

    1981-07-01

    Using photothermal deflection spectroscopy, the optical absorption of various a-Si:H films was investigated in the range of 2.1 to 0.6 eV. An absorption shoulder which depends on deposition conditions and on doping was found and was attributed to dangling bonds. The exponential edge broadens with increasing spin density.

  12. Bandedge absorption of GaAsN films measured by the photothermal deflection spectroscopy

    NASA Astrophysics Data System (ADS)

    Beaudoin, M.; Chan, I. C. W.; Beaton, D.; Elouneg-Jamroz, M.; Tiedje, T.; Whitwick, M.; Young, E. C.; Young, J. F.; Zangenberg, N.

    2009-03-01

    The optical absorption of GaAsN films grown by molecular beam epitaxy on GaAs substrates is measured using the mirage effect photothermal deflection spectroscopy (PDS). The PDS spectra were fitted with a modified Fernelius model, which takes into account multiple reflections within the GaAsN layer and GaAs substrate. This allowed the extraction of bandedge parameters for a series of GaAsN films with N content varying from 0.24% to 1.4% N. All films show a clear Urbach absorption edge with a composition-dependent bandgap consistent with literature and Urbach slope parameters roughly 3 times larger than GaAs values.

  13. Solutions of the heat conduction equation in multilayers for photothermal deflection experiments

    NASA Technical Reports Server (NTRS)

    Mcgahan, William A.; Cole, K. D.

    1992-01-01

    Analytical expressions for temperature and laser beam deflection in multilayer medium is derived using Green function techniques. The approach is based on calculation of the normal component of heat fluxes across the boundaries, from which either the beam deflections or the temperature anywhere in space can be found. A general expression for the measured signals for the case of four-quadrant detection is also presented and compared with previous calculations of detector response for finite probe beams.

  14. Wideband low-noise optical beam deflection sensor with photothermal excitation for liquid-environment atomic force microscopy.

    PubMed

    Fukuma, Takeshi

    2009-02-01

    I developed a wideband low-noise optical beam deflection sensor with a photothermal cantilever excitation system for liquid-environment atomic force microscopy. The developed sensor has a 10 MHz bandwidth and 4.7 fm/sq.rt.Hz deflection noise density in water. The theoretically limited noise performance (i.e., the noise level limited only by the photodiode shot noise) has been achieved in liquid for the first time. Owing to the wide bandwidth and the replaceable focus lens design, the sensor is applicable to cantilevers with various dimensions. The deflection noise densities of less than 7.8 fm/sq.rt.Hz have been achieved in water for cantilevers with lengths from 35 to 125 microm. The ideal amplitude and phase versus frequency curves without distortion are obtained with the developed photothermal excitation system. The excitation system is applicable to relatively stiff cantilevers (>20 N/m) in liquid, making it possible to obtain true atomic-resolution images in liquid. True atomic-resolution imaging of mica in water is demonstrated using the developed deflection sensor and the photothermal excitation system. PMID:19256653

  15. Photothermal technique in cell microscopy studies

    NASA Astrophysics Data System (ADS)

    Lapotko, Dmitry; Chebot'ko, Igor; Kutchinsky, Georgy; Cherenkevitch, Sergey

    1995-01-01

    Photothermal (PT) method is applied for a cell imaging and quantitative studies. The techniques for cell monitoring, imaging and cell viability test are developed. The method and experimental set up for optical and PT-image acquisition and analysis is described. Dual- pulsed laser set up combined with phase contrast illumination of a sample provides visualization of temperature field or absorption structure of a sample with spatial resolution 0.5 micrometers . The experimental optics, hardware and software are designed using the modular principle, so the whole set up can be adjusted for various experiments: PT-response monitoring or photothermal spectroscopy studies. Sensitivity of PT-method provides the imaging of the structural elements of live (non-stained) white blood cells. The results of experiments with normal and subnormal blood cells (red blood cells, lymphocytes, neutrophyles and lymphoblasts) are reported. Obtained PT-images are different from optical analogs and deliver additional information about cell structure. The quantitative analysis of images was used for cell population comparative diagnostic. The viability test for red blood cell differentiation is described. During the study of neutrophyles in norma and sarcoidosis disease the differences in PT-images of cells were found.

  16. Thermal characterization of Li-ion cell electrodes by photothermal deflection spectroscopy

    NASA Astrophysics Data System (ADS)

    Loges, André; Herberger, Sabrina; Werner, Daniel; Wetzel, Thomas

    2016-09-01

    Contactless and temperature-dependent evaluation of thermal diffusivities of Li-ion cell electrodes based on photothermal deflection spectroscopy (PDS) measurements is introduced and applied to electrodes from three prismatic hardcase Li-ion cells. The accuracy of the method is validated using reference materials, which cover a wide range of thermal diffusivity. The effective thermal diffusivities of the three anode and cathode coatings and of the current collectors are determined in the temperature range of 5-45 °C. Furthermore, the temperature-dependent specific heat capacity of the electrodes is evaluated by differential scanning calorimetry (DSC) measurements in the same temperature range. Based on the experimental results the through-plane and in-plane thermal conductivity of the electrodes is calculated and compared to previously reported values. The results indicate significant influence of the porosity and manufacturing process on the effective thermal conductivity of the electrodes. The three mayor impact factors on thermal conductivity of electrodes are (i) composition, (ii) morphology of the coating and (iii) the thickness ratio of coating to current collector.

  17. Thermal diffusivity of lead-free solders measured by photothermal beam deflection. Effect of the surrounding media

    NASA Astrophysics Data System (ADS)

    Prior, P.; Gören, A.; Macedo, F.; Ferreira, J. A.; Soares, D.

    2005-06-01

    The search for lead-free alloys has increased markedly in recent years, as new environmental regulations have been approved. In particular, traditional solders used in the microelectronics industry are now being gradually replaced by new lead-free materials.

    In this work, we report measurements of the thermal properties of new Sn-based alloys with varying contents of Bi, Al, Ag and Cu, which have been developed as alternatives to the traditional lead-based solders used in microelectronic assemblies.

    Measurements of thermal diffusivity were performed using the photothermal beam deflection [1] (PBD) technique. We tested the influence of the surrounding media in the quality of the measurements. We found out that the sensitivity can be greatly improved using as surrounding medium fluids with very low thermal diffusivities and high refractive index change with temperature (partialn /partialT ).

    Although a more general physical characterisation of the lead-free alloys, concerning measurements of electrical resistivity, mechanical properties and structural characterisation, is still under way, these thermal measurements combined with information about the electrical resistivity show that these alloys can be good alternatives for soldering applications.

  18. Photothermal deflection of laser beam as means to characterize thermal properties of biological tissue: numerical study

    NASA Astrophysics Data System (ADS)

    Gutierrez-Herrera, Enoch; Sánchez-Pérez, Celia; García-Cadena, Carlos A.; Hernández-Ruiz, Joselín.

    2015-08-01

    Non-subjective and early diagnostic technique for liver fibrosis may decrease morbidity in patients and reduce medical costs. Liver fibrosis results in changes in density and thermal properties of tissue. In this work, we evaluate numerically the feasibility of using the optical beam deflection method (OBDM) by means of a thermo-optic material in contact with liver tissue to quantitate changes in thermal conduction. We use the finite-difference method to model the heat transfer in liver and acrylic slab. The response required for thermal characterization for different fibrosis stages is assessed by calculating the deflection angle using ray trace analysis. Numerical study shows the potential of the OBDM for developing an optical-integrated sensor as non-subjective diagnostic technique for liver fibrosis.

  19. Investigation of electrical and optothermal properties of Si-doped GaSb epitaxial layers by the Hall effect, PL measurement and photothermal deflection spectroscopy

    NASA Astrophysics Data System (ADS)

    Abroug, S.; Saadallah, F.; Genty, F.; Yacoubi, N.

    2009-11-01

    The aim of this work is to investigate the influence of Si-doping on the optical, thermal and electrical properties of GaSb epitaxial layers. Such an influence was quantified through photoluminescence (PL), mirage effect (photothermal spectroscopy) and Hall effect measurements. Several GaSb samples, grown by Molecular Beam Epitaxy (MBE) on (100)-oriented GaAs semiinsulating substrates, with different Si-doping levels ranging from 4.95 × 1016at .cm-3 up to 8.11.1019 at .cm-3 were tested. As a comparison, the same measurements were also performed on a GaSb non intentionally doped layer. The Hall effect data shows a monotonic decrease in carrier mobility when the hole concentration increase. The effect of band-to-band, band-impurity transitions on the PL gap E0 and the influence of high impurity concentration on the PL and absorption spectra have been also studied. Finally, the optical absorption changes induced by Si-doping on GaSb samples were investigated by photothermal deflection. It was shown that this technique allows a very precise deduction of the real interband gap energy of a semiconductor material as GaSb. Thermal conductivities were also deduced from the photothermal deflection measurements. The found values are very low due to the thermal resistivity of the layer-substrate interface but also due to the lattice-mismatch between GaSb epilayers and the GaAs substrate. However, the contribution of the free carriers to the thermal conductivity, with a high p-doping level (p > 1019cm-3), could be highlighted.

  20. Sandwich concept: enhancement for direct absorption measurements by laser-induced deflection (LID) technique

    NASA Astrophysics Data System (ADS)

    Mühlig, Ch.; Bublitz, S.; Paa, W.

    2012-11-01

    The new sandwich concept for absolute photo-thermal absorption measurements using the laser induced deflection (LID) technique is introduced and tested in comparison to the standard LID concept. The sandwich concept's idea is the decoupling of the optical materials for the pump and probe beams by placing a sample of investigation in between two optical (sandwich) plates. The pump beam is guided through the sample whereas the probe beams are deflected within the sandwich plates by the thermal lens that is generated by heat transfer from the irradiated sample. Electrical simulation and laser experiments reveal that using appropriate optical materials for the sandwich plates, the absorption detection limit for photo-thermally insensitive materials can be lowered by up to two orders of magnitude. Another advantage of the sandwich concept, the shrinking of the currently required minimum sample size, was used to investigate the laser induced absorption change in a Nd:YVO4 crystal at 1030nm. It was found that the absorption in Nd:YVO4 lowers due to the laser irradiation but partially recovers during irradiation breaks. Furthermore, absorption spectroscopy has been performed at two LBO crystals in the wavelength range 410...600nm to study the absorption structure around the SHG wavelengths of common high power lasers based on Neodymium doped laser crystals.

  1. Development of infrared photothermal deflection spectroscopy (mirage effect) for analysis of condensed-phase aerosols collected in a micro-orifice uniform deposit impactor.

    PubMed

    Dada, Oluwatosin O; Bialkowski, Stephen E

    2008-12-01

    The potential of mid-infrared photothermal deflection spectrometry for aerosol analysis is demonstrated. Ammonium nitrate aerosols are deposited on a flat substrate using a micro-orifice uniform deposit impactor (MOUDI). Photothermal spectroscopy with optical beam deflection (mirage effect) is used to detect deposited aerosols. Photothermal deflection from aerosols is measured by using pulsed infrared laser light to heat up aerosols collected on the substrate. The deflection signal is obtained by measuring the position of a spot from a beam of light as it passes near the heated surface. The results indicate non-rotating impaction as the preferred MOUDI impaction method. Energy-dependent photothermal measurement shows a linear relationship between signal and laser intensity, and no loss of signal with time is observed. The detection limit from the signal-mass curve is 7.31 ng. For 30 minutes collection time and 30 L/min flow rate of the impactor, the limit of detection in terms of aerosol mass concentration is 0.65 microg m(-3). PMID:19094392

  2. Enthalpy Changes during Photosynthetic Water Oxidation Tracked by Time-Resolved Calorimetry Using a Photothermal Beam Deflection Technique☆☆☆

    PubMed Central

    Krivanek, Roland; Dau, Holger; Haumann, Michael

    2008-01-01

    The energetics of the individual reaction steps in the catalytic cycle of photosynthetic water oxidation at the Mn4Ca complex of photosystem II (PSII) are of prime interest. We studied the electron transfer reactions in oxygen-evolving PSII membrane particles from spinach by a photothermal beam deflection technique, allowing for time-resolved calorimetry in the micro- to millisecond domain. For an ideal quantum yield of 100%, the enthalpy change, ΔH, coupled to the formation of the radical pair YZ⋅+QA− (where YZ is Tyr-161 of the D1 subunit of PSII) is estimated as −820 ± 250 meV. For a lower quantum yield of 70%, the enthalpy change is estimated to be −400 ± 250 meV. The observed nonthermal signal possibly is due to a contraction of the PSII protein volume (apparent ΔV of about −13 Å3). For the first time, the enthalpy change of the O2-evolving transition of the S-state cycle was monitored directly. Surprisingly, the reaction is only slightly exergonic. A value of ΔH(S3 ⇒ S0) of −210 meV is estimated, but also an enthalpy change of zero is within the error range. A prominent nonthermal photothermal beam deflection signal (apparent ΔV of about +42 Å3) may reflect O2 and proton release from the manganese complex, but also reorganization of the protein matrix. PMID:17993488

  3. Direct Correlation of Charge Transfer Absorption with Molecular Donor:Acceptor Interfacial Area via Photothermal Deflection Spectroscopy.

    PubMed

    Buchaca-Domingo, Ester; Vandewal, Koen; Fei, Zhuping; Watkins, Scott E; Scholes, Fiona H; Bannock, James H; de Mello, John C; Richter, Lee J; DeLongchamp, Dean M; Amassian, Aram; Heeney, Martin; Salleo, Alberto; Stingelin, Natalie

    2015-04-29

    Here we show that the charge transfer (CT) absorption signal in bulk-heterojunction solar cell blends, measured by photothermal deflection spectroscopy, is directly proportional to the density of molecular donor:acceptor interfaces. Since the optical transitions from the ground state to the interfacial CT state are weakly allowed at photon energies below the optical gap of both the donor and acceptor, we can exploit the use of this sensitive linear absorption spectroscopy for such quantification. Moreover, we determine the absolute molar extinction coefficient of the CT transition for an archetypical polymer:fullerene interface. The latter is ∼100 times lower than the extinction coefficient of the donor chromophore involved, allowing us to experimentally estimate the transition dipole moment as 0.3 D and the electronic coupling between the ground and CT states to be on the order of 30 meV. PMID:25856143

  4. Measurement of thermal and optical properties of CR-39 solid-state nuclear detector by photothermal deflection

    NASA Astrophysics Data System (ADS)

    Mohammed, K. I.; Azawe, M. I.

    2013-08-01

    The thermal and optical properties of the nuclear detector CR-39 were studied in light of the demand for CR-39 and its novel physical properties, as well as its technological implications in many fields. Thermal diffusivity is the most important parameter when this detector is exposed to nuclear radiation and when consequent heat transfer processes influence the photothermal deflection spectroscopy. Thermal-induced effects on the surface of the CR-39 detector were studied using transient heat diffusion simulations. The resulting thermal deformation due to alpha particle irradiation of CR-39 will be presented. Irradiation of CR-39 by α-particles was found to lower the refractive index change with temperature. The temperature distribution was studied numerically by solving the heat diffusion equation to illustrate the effects of α-particle exposure on the CR-39. The thermal diffusivity of exposed CR-39 is the primary subject of this article.

  5. Material characterization with top-hat cw laser induced photothermal techniques: A short review

    NASA Astrophysics Data System (ADS)

    Astrath, N. G. C.; Shen, J.; Baesso, M. L.; Astrath, F. B. G.; Malacarne, L. C.; Pedreira, P. R. B.; Bento, A. C.; Zhou, J.

    2010-03-01

    In this work, we present a short review of the recent development of the theoretical models for top-hat cw laser induced spectroscopies of thermal lens and thermal mirror. With the same probe and top-hat excitation lasers, an apparatus is set up to concurrently measure both thermal lens and thermal mirror effects of transparent samples. With the theoretical models and the experimental apparatus, not only optical and thermal properties are measured, but also the fluorescence quantum coefficient and the temperature coefficient of the optical path length of a fluorescent sample are simultaneously determined with no need of any reference sample. Mechanical properties also could be measured. Opaque samples are also studied using top-hat cw laser thermal mirror and top-hat photothermal deflection techniques to determine thermal properties (e.g., thermal conductivity and unit volume specific heat). This work shows that the combined top-hat cw laser photothermal techniques are useful for nondestructive evaluation of both transparent and opaque samples with a less expensive non-TEM00 Gaussian laser.

  6. Direct and absolute absorption measurements in optical materials and coatings by laser induced deflection (LID) technique

    NASA Astrophysics Data System (ADS)

    Mühlig, Ch.

    2011-11-01

    Different strategies of the laser induced deflection (LID) technique for direct and absolute absorption measurements are presented. Besides selected strategies for bulk and coating absorption measurements, respectively, a new strategy is introduced allowing the transfer of the LID technique to very small samples and to significantly increase the sensitivity for materials with a very weak photo-thermal response. Additionally, an emphasis is placed on the importance of the calibration procedure. The electrical calibration of the LID setup is compared to two other approaches that use either doped samples or highly absorptive reference samples in combination with numerical simulations. Applying the LID technique, we report on the characterization of AR coated LBO crystals used in high power NIR/VIS laser applications. The comparison of different LBO crystals shows that there are significant differences in both, the AR coating and the LBO bulk absorption. These differences are much larger at 515 nm than at 1030 nm. Absorption spectroscopy measurements combining LID technique with a high power OPO laser system indicate that the coating process affects the LBO bulk absorption properties. Furthermore, the change of the absorption upon 1030 nm laser irradiation of a Nd:YVO4 laser crystal is investigated and compared to recent results. Finally, Ytterbium doped silica raw materials for high power fiber lasers are characterized with respect to the absorption induced attenuation at 1550 nm in order to compare these data with the total attenuation obtained for the subsequently manufactured laser active fibers.

  7. Direct and absolute absorption measurements in optical materials and coatings by laser induced deflection (LID) technique

    NASA Astrophysics Data System (ADS)

    Mühlig, Ch.

    2012-01-01

    Different strategies of the laser induced deflection (LID) technique for direct and absolute absorption measurements are presented. Besides selected strategies for bulk and coating absorption measurements, respectively, a new strategy is introduced allowing the transfer of the LID technique to very small samples and to significantly increase the sensitivity for materials with a very weak photo-thermal response. Additionally, an emphasis is placed on the importance of the calibration procedure. The electrical calibration of the LID setup is compared to two other approaches that use either doped samples or highly absorptive reference samples in combination with numerical simulations. Applying the LID technique, we report on the characterization of AR coated LBO crystals used in high power NIR/VIS laser applications. The comparison of different LBO crystals shows that there are significant differences in both, the AR coating and the LBO bulk absorption. These differences are much larger at 515 nm than at 1030 nm. Absorption spectroscopy measurements combining LID technique with a high power OPO laser system indicate that the coating process affects the LBO bulk absorption properties. Furthermore, the change of the absorption upon 1030 nm laser irradiation of a Nd:YVO4 laser crystal is investigated and compared to recent results. Finally, Ytterbium doped silica raw materials for high power fiber lasers are characterized with respect to the absorption induced attenuation at 1550 nm in order to compare these data with the total attenuation obtained for the subsequently manufactured laser active fibers.

  8. Absorption measurement of thin films by using photothermal techniques: The influence of thermal properties

    SciTech Connect

    Wu, Z.L.; Kuo, P.K.; Thomas, R.L.; Fan, Z.X.

    1995-12-31

    Photothermal techniques are widely used for measuring optical absorption of thin film coatings. In these applications the calibration of photothermal signal is typically based on the assumption that the thermal properties of the thin film make very little contribution. In this paper we take mirage technique as an example and present a detailed analysis of the influence of thin film thermal properties on absorption measurements. The results show that the traditional calibration method is not valid on surprisingly many situations.

  9. Direct measurement of Urbach tail and gap state absorption in CuGaSe2 thin films by photothermal deflection spectroscopy and the constant photocurrent method

    NASA Astrophysics Data System (ADS)

    Meeder, A.; Marron, D. Fuertes; Rumberg, A.; Lux-Steiner, M. Ch.; Chu, V.; Conde, J. P.

    2002-09-01

    The applicability of photothermal deflection spectroscopy (PDS) and the constant photocurrent method (CPM) to chemical vapor deposited and physical vapor deposited CuGaSe2 (CGSe) thin films is investigated. Process dependent variations in direct band-gap energies, Urbach tail widths, bulk and surface defect densities of the films are given as a function of composition. Differences in the PDS and CPM absorption spectra of more than one order of magnitude are found. Using the standard a-Si theory of PDS and CPM analysis, a two-layer system consisting of a defect-rich near-surface layer and a less defective bulk layer is found in device-quality films. Optical improvements due to the Ga+Se annealing step as a second stage of the growth process result in a reduced bulk defect density while the near-surface defect density remains unchanged.

  10. Optical and Thermal Analysis of the Time Evolution of Curing in Resins by Photothermal Techniques

    NASA Astrophysics Data System (ADS)

    Martínez-Torres, P.; Zambrano-Arjona, M.; Aguilar, G.; Alvarado-Gil, J. J.

    2012-11-01

    Four shades of a commercial visible-light curing dental resin are analyzed using photothermal techniques. The thermal effusivities of the dental resin shades before curing are measured using a variant of the conventional photoacoustic technique. The thermal diffusivities before and after curing are measured using infrared photothermal radiometry in the forward emission configuration. The time evolution process of the photocuring resin is monitored by photothermal radiometry in the forward and backward emission configurations. Inversion of the time evolution signal of the different configurations used permits one to obtain the time evolution of the thermal and optical properties during the photocuring. The thermal effusivity and thermal diffusivity exhibit exponential growth, while the optical absorption decreases exponentially due to the curing process. The relationship of these phenomena with the decrease of monomer concentration induced by the curing is discussed.

  11. Evaluation of surface and bulk qualities of semiconductor materials by a laser-induced photothermal technique

    NASA Astrophysics Data System (ADS)

    Dong, Jingtao; Chen, Jian; Sun, Shiwen; Zhang, Dawei; Zhuang, Songlin; Wu, Zhouling

    2015-05-01

    Non-destructive evaluation of defects for semiconductor materials is critical to the quality control process. The existing evaluation methods, including radiographic testing, ultrasonic detection, fluorescence and infrared imaging, are widely used in industrial applications. In this paper an instrument based on laser-induced photothermal technique was applied to study various semiconductor materials. With a specially arranged pump-probe configuration, this system can do three dimensional mapping of local properties and defects. By using this photothermal instrument, several semiconductors, such as bulk CdZnTe (CZT) crystals and monocrystalline silicon wafers under different processing conditions, were investigated. The surface and internal structures and defects of these materials were tested nondestructively by the 3-D photothermal microscope. The results show intersting correlation between the photothermal characterizations and the processing conditions. In addition, the details of the development of the 3-D photothermal microscope were also presented. The system provides user-friendly operations of the defects characterization process and shows great potential of application for characterization of semiconductor materials.

  12. Thermal Characterization of Carbon Nanotubes by Photothermal Techniques

    NASA Astrophysics Data System (ADS)

    Leahu, G.; Li Voti, R.; Larciprete, M. C.; Sibilia, C.; Bertolotti, M.; Nefedov, I.; Anoshkin, I. V.

    2015-06-01

    Carbon nanotubes (CNTs) are multifunctional materials commonly used in a large number of applications in electronics, sensors, nanocomposites, thermal management, actuators, energy storage and conversion, and drug delivery. Despite recent important advances in the development of CNT purity assessment tools and atomic resolution imaging of individual nanotubes by scanning tunnelling microscopy and high-resolution transmission electron microscopy, the macroscale assessment of the overall surface qualities of commercial CNT materials remains a great challenge. The lack of quantitative measurement technology to characterize and compare the surface qualities of bulk manufactured and engineered CNT materials has negative impacts on the reliable and consistent nanomanufacturing of CNT products. In this paper it is shown how photoacoustic spectroscopy and photothermal radiometry represent useful non-destructive tools to study the optothermal properties of carbon nanotube thin films.

  13. Photothermal Deflection Experiments: Comparison of Existing Theoretical Models and Their Applications to Characterization of -Based Thin Films

    NASA Astrophysics Data System (ADS)

    Korte, Dorota; Franko, Mladen

    2014-12-01

    A method for determination of thermooptical, transport, and structural parameters of -based thin films is presented. The measurements were conducted using beam deflection spectroscopy (BDS) and supporting theoretical analysis performed in the framework of complex geometrical optics providing a novel method of BDS data modeling. It was observed that the material's thermal parameters strongly depend on sample properties determining its photocatalytic activity such as the energy bandgap, carrier lifetime, surface structure, or porosity. Because of that, the fitting procedure of the theoretical dependence into experimental data was developed to determine the sample's thermal parameters, on the basis of which the information about its structure was further found. The obtained results were compared to those based on geometrical and wave optics approaches that are currently widely used for that purpose. It was demonstrated that the choice of the proper model for data modeling is a crucial point when performing such a type of analysis.

  14. Application of photoacoustic and photothermal techniques for heat conduction measurements in a free-standing chemical vapor-deposited diamond film

    SciTech Connect

    Glorieux, C.; De Groote, J.; Lauriks, W.; Thoen, J. ); Fivez, J. EHSAL, Brussel Universitaire Faculteiten St. Ignatius, Antwerpen )

    1993-11-01

    Heat conduction in a free-standing chemical vapor-deposited polycrystalline diamond film has been investigated by means of combined front and rear photoacoustic signal detection techniques and also by means of a mirage' photothermal beam deflection technique. The results obtained with the different techniques are consistent with a value of [alpha] = (5.5 [+-] 0.4) [times] 10[sup [minus]4]m[sup 2][center dot]s[sup [minus]1] for thermal diffusivity, resulting in a value of k -(9.8 [+-] 0.7) [times] 10[sup 2]W m[sup [minus]1]. K[sup [minus]1] for thermal conductivity when literature values for the density and heat capacity for natural diamond are used. 25 refs., 7 figs.

  15. Thermal conductivity of organic semi-conducting materials using 3omega and photothermal radiometry techniques

    NASA Astrophysics Data System (ADS)

    Reisdorffer, Frederic; Garnier, Bertrand; Horny, Nicolas; Renaud, Cedric; Chirtoc, Mihai; Nguyen, Thien-Phap

    2014-12-01

    Organic semiconductors for opto-electronic devices show several defects which can be enhanced while increasing the operating temperature. Their thermal management and especially the reduction of their temperature are of great interest. For the heat transfer study, one has to measure the thermal conductivity of thin film organic materials. However the major difficulty for this measurement is the very low thickness of the films which needs the use of very specific techniques. In our work, the 3-omega and photothermal radiometric methods were used to measure the thermal conductivity of thin film organic semiconducting material (Alq3). The measurements were performed as function of the thin film thickness from 45 to 785 nm and also of its temperature from 80 to 350 K. With the 3 omega method, a thermal conductivity value of 0.066 W.m-1K-1 was obtained for Alq3 thin film of 200 nm at room temperature, in close agreement with the photothermal value. Both techniques appear to be complementary: the 3 omega method is easier to implement for large temperature range and small thicknesses down to a few tens of nanometers whereas the photothermal method is more suitable for thicknesses over 200nm since it provides additional information such as the thin film volumetric heat capacity.

  16. Photothermal measurements of superconductors

    SciTech Connect

    Kino, G.S.; Studenmund, W.R.; Fishman, I.M.

    1996-12-31

    A photothermal technique has been used to measure diffusion and critical temperature in high temperature superconductors. The technique is particularly suitable for determining material quality and inhomogeneity.

  17. Spatially localized measurement of thermal conductivity using a hybrid photothermal technique

    SciTech Connect

    David H Hurley; Marat Khafizov; Zilong Hua; Rory Kennedy; Heng Ban

    2012-05-01

    A photothermal technique capable of measuring thermal conductivity with micrometer lateral resolution is presented. This technique involves measuring separately the thermal diffusivity, D, and thermal effusivity, e, to extract the thermal conductivity, k=(e2/D)1/2. To generalize this approach, sensitivity analysis was conducted for materials having a range of thermal conductivities. Experimental validation was sought using two substrate materials, SiO2 and CaF2, both coated with thin titanium films. The measured conductivities compare favorably with literature values.

  18. Deflection of polarised radiation - Relative phase delay technique. [photon geodesic motion variations

    NASA Technical Reports Server (NTRS)

    Dennison, B.; Melnick, G.; Harwit, M.; Sato, T.; Stelzried, C. T.; Jauncey, D.

    1978-01-01

    The article discusses the geodesic motion of photons, considering particularly whether oppositely polarized photons fall at the same rate. It is assumed that orthogonally polarized photons would be equally deflected by the gravitational field of a nonrotating mass. Upon the introduction of rotation, the angular momentum of the deflecting source couples to the photon spin through gravitational field action. Thus there arise separate trajectories for orthogonal polarizations. Searching for changes in polarization in a deflected beam is accomplished by a relative phase delay technique. If the beam is split into orthogonal linear polarization, final polarization is elliptical. Experiments have been performed on searching for ellipticity developments in the linearly polarized carrier waves from Helios 1 and 2, and the results are presented.

  19. Thermal properties measurements in biodiesel oils using photothermal techniques

    NASA Astrophysics Data System (ADS)

    Castro, M. P. P.; Andrade, A. A.; Franco, R. W. A.; Miranda, P. C. M. L.; Sthel, M.; Vargas, H.; Constantino, R.; Baesso, M. L.

    2005-08-01

    In this Letter, thermal lens and open cell photoacoustic techniques are used to measure the thermal properties of biodiesel oils. The absolute values of the thermal effusivity, thermal diffusivity, thermal conductivity and the temperature coefficient of the refractive index were determined for samples obtained from soy, castor bean, sunflower and turnip. The results suggest that the employed techniques may be useful as complementary methods for biodiesel certification.

  20. Pulsed photothermal mirror technique: characterization of opaque materials.

    PubMed

    Capeloto, O A; Lukasievicz, G V B; Zanuto, V S; Herculano, L S; Souza Filho, N E; Novatski, A; Malacarne, L C; Bialkowski, S E; Baesso, M L; Astrath, N G C

    2014-11-20

    The time-resolved thermal mirror technique is developed under pulsed laser excitation for quantitative measurement of thermal and mechanical properties of opaque materials. Heat diffusion and thermoelastic equations are solved analytically for pulsed excitation assuming surface absorption and an instantaneous pulse. Analytical results for the temperature change and surface displacement in the sample are compared to all-numerical solutions using finite element method analysis accounting for the laser pulse width and sample geometry. Experiments are performed that validate the theoretical model and regression fitting is performed to obtain the thermal diffusivity and the linear thermal expansion coefficient of the samples. The values obtained for these properties are in agreement with literature data. The technique is shown to be useful for quantitative determinations of the physics properties of metals with high thermal diffusivity. PMID:25607877

  1. Thermal Effusivity of Vegetable Oils Obtained by a Photothermal Technique

    NASA Astrophysics Data System (ADS)

    Cervantes-Espinosa, L. M.; de L. Castillo-Alvarado, F.; Lara-Hernández, G.; Cruz-Orea, A.; Hernández-Aguilar, C.; Domínguez-Pacheco, A.

    2014-10-01

    Thermal properties of several vegetable oils such as soy, corn, and avocado commercial oils were obtained by using a photopyroelectric technique. The inverse photopyroelectric configuration was used in order to obtain the thermal effusivity of the oil samples. The theoretical equation for the photopyroelectric signal in this configuration, as a function of the incident light modulation frequency, was fitted to the experimental data in order to obtain the thermal effusivity of these samples. The obtained results are in good agreement with the thermal effusivity reported for other vegetable oils. All measurements were done at room temperature.

  2. Nanosecond pulsed laser ablation of Ge investigated by employing photoacoustic deflection technique and SEM analysis

    NASA Astrophysics Data System (ADS)

    Yaseen, Nazish; Bashir, Shazia; Shabbir, Muhammad Kaif; Jalil, Sohail Abdul; Akram, Mahreen; Hayat, Asma; Mahmood, Khaliq; Haq, Faizan-ul; Ahmad, Riaz; Hussain, Tousif

    2016-06-01

    Nanosecond pulsed laser ablation phenomena of single crystal Ge (100) has been investigated by employing photoacoustic deflection as well as SEM analysis techniques. Nd: YAG laser (1064 nm, 10 ns, 1-10 Hz) at various laser fluences ranging from 0.2 to 11 J cm-2 is employed as pump beam to ablate Ge targets. In order to evaluate in-situe ablation threshold fluence of Ge by photoacoustic deflection technique, Continuous Wave (CW) He-Ne laser (632 nm, power 10 mW) is employed as a probe beam. It travels parallel to the target surface at a distance of 3 mm and after passing through Ge plasma it causes deflection due to density gradient of acoustic waves. The deflected signal is detected by photodiode and is recorded by oscilloscope. The threshold fluence of Ge, the velocity of ablated species and the amplitude of the deflected signal are evaluated. The threshold fluence of Ge comes out to be 0.5 J cm-2 and is comparable with the analytical value. In order to compare the estimated value of threshold with ex-situe measurements, the quantitative analysis of laser irradiated Ge is performed by using SEM analysis. For this purpose Ge is exposed to single and multiple shots of 5, 10, 50 and 100 at various laser fluences ranging from 0.2 to 11 J cm-2. The threshold fluence for single and multiple shots as well as incubation coefficients are evaluated. It is observed that the value of incubation co-efficient decreases with increasing number of pulses and is therefore responsible for lowering the threshold fluence of Ge. SEM analysis also reveals the growth of various features such as porous structures, non-uniform ripples and blisters on the laser irradiated Ge. It is observed that both the fluence as well as number of laser shots plays a significant role for the growth of these structures.

  3. The study of frequency-scan photothermal reflectance technique for thermal diffusivity measurement.

    PubMed

    Hua, Zilong; Ban, Heng; Hurley, David H

    2015-05-01

    A frequency scan photothermal reflectance technique to measure thermal diffusivity of bulk samples is studied in this manuscript. Similar to general photothermal reflectance methods, an intensity-modulated heating laser and a constant intensity probe laser are used to determine the surface temperature response under sinusoidal heating. The approach involves fixing the distance between the heating and probe laser spots, recording the phase lag of reflected probe laser intensity with respect to the heating laser frequency modulation, and extracting thermal diffusivity using the phase lag-(frequency)(1/2) relation. The experimental validation is performed on three samples (SiO2, CaF2, and Ge), which have a wide range of thermal diffusivities. The measured thermal diffusivity values agree closely with the literature values. Compared to the commonly used spatial scan method, the experimental setup and operation of the frequency scan method are simplified, and the uncertainty level is equal to or smaller than that of the spatial scan method. PMID:26026545

  4. The study of frequency-scan photothermal reflectance technique for thermal diffusivity measurement

    DOE PAGESBeta

    Hua, Zilong; Ban, Heng; Hurley, David H.

    2015-05-05

    A frequency scan photothermal reflectance technique to measure thermal diffusivity of bulk samples is studied in this manuscript. Similar to general photothermal reflectance methods, an intensity-modulated heating laser and a constant intensity probe laser are used to determine the surface temperature response under sinusoidal heating. The approach involves fixing the distance between the heating and probe laser spots, recording the phase lag of reflected probe laser intensity with respect to the heating laser frequency modulation, and extracting thermal diffusivity using the phase lag – (frequency)1/2 relation. The experimental validation is performed on three samples (SiO2, CaF2 and Ge), which havemore » a wide range of thermal diffusivities. The measured thermal diffusivity values agree closely with literature values. Lastly, compared to the commonly used spatial scan method, the experimental setup and operation of the frequency scan method are simplified, and the uncertainty level is equal to or smaller than that of the spatial scan method.« less

  5. The study of frequency-scan photothermal reflectance technique for thermal diffusivity measurement

    SciTech Connect

    Hua, Zilong; Ban, Heng; Hurley, David H.

    2015-05-05

    A frequency scan photothermal reflectance technique to measure thermal diffusivity of bulk samples is studied in this manuscript. Similar to general photothermal reflectance methods, an intensity-modulated heating laser and a constant intensity probe laser are used to determine the surface temperature response under sinusoidal heating. The approach involves fixing the distance between the heating and probe laser spots, recording the phase lag of reflected probe laser intensity with respect to the heating laser frequency modulation, and extracting thermal diffusivity using the phase lag – (frequency)1/2 relation. The experimental validation is performed on three samples (SiO2, CaF2 and Ge), which have a wide range of thermal diffusivities. The measured thermal diffusivity values agree closely with literature values. Lastly, compared to the commonly used spatial scan method, the experimental setup and operation of the frequency scan method are simplified, and the uncertainty level is equal to or smaller than that of the spatial scan method.

  6. RAPID COMMUNICATION: Simultaneous determination of anisotropic thermal conductivities of liquid crystals by means of a photothermal self-diffracting technique

    NASA Astrophysics Data System (ADS)

    Ono, Hiroshi; Shibata, Kazuaki

    2000-11-01

    Anisotropic thermal conductivities of liquid crystals were simultaneously determined by means of a photothermal self-diffracting technique. A single-mode laser beam with Gaussian profile excited refractive index distribution due to the photothermal effect in homogeneously-aligned liquid-crystal films. The refractive index distribution, which is affected by thermal conductivities of liquid crystals, transformed the incident Gaussian beam. The laser beam was self-diffracted and thermal conductivities of liquid crystals were determined by characterizing the beam profile by both Kirchhoff's diffraction theory and heat conduction analysis.

  7. Some potential uses of photothermal detection for DNA microarray quantification

    NASA Astrophysics Data System (ADS)

    Getin, Stephane; Chaton, Patrick; Vinet, Francoise; Poupinet, Ludovic; Pelle, Catherine; Puget, Pierre; Ginot, Frederic; Novelli, Armelle

    2003-07-01

    Photothermal deflection technique is a very sensitive mean to measure optical absorbance. This study is aimed at evaluating its potentiality in order to detect hybridation and to monitor quality control. The principle of the technique relies on the fact that nucleic acids present the property to absorb light between 220 nm to 280 nm. A first theoretical approach based on solving light and thermal equations demonstrates the ability of photothermal deflection to detect hybridisation. This point is checked through several experimentations with oligonucleotid with 32 mers targets lengths. An important point to stres is the specificity of the signals obtained and the ability of automation of the reading with image processing algorithms. At last we focus our attention on the ability of this technique to in-situ synthesis process. Our experimental study shows the ability of this characterisation with a detection sensitivity of one base.

  8. All-optical optoacoustic microscopy system based on probe beam deflection technique

    NASA Astrophysics Data System (ADS)

    Maswadi, Saher M.; Tsyboulskic, Dmitri; Roth, Caleb C.; Glickman, Randolph D.; Beier, Hope T.; Oraevsky, Alexander A.; Ibey, Bennett L.

    2016-03-01

    It is difficult to achieve sub-micron resolution in backward mode OA microscopy using conventional piezoelectric detectors, because of wavefront distortions caused by components placed in the optical path, between the sample and the objective lens, that are required to separate the acoustic wave from the optical beam. As an alternate approach, an optoacoustic microscope (OAM) was constructed using the probe beam deflection technique (PBDT) to detect laserinduced acoustic signals. The all-optical OAM detects laser-generated pressure waves using a probe beam passing through a coupling medium, such as water, filling the space between the microscope objective lens and sample. The acoustic waves generated in the sample propagate through the coupling medium, causing transient changes in the refractive index that deflect the probe beam. These deflections are measured with a high-speed, balanced photodiode position detector. The deflection amplitude is directly proportional to the magnitude of the acoustic pressure wave, and provides the data required for image reconstruction. The sensitivity of the PBDT detector expressed as noise equivalent pressure was 12 Pa, comparable to that of existing high-performance ultrasound detectors. Because of the unimpeded working distance, a high numerical aperture objective lens, i.e. NA = 1, was employed in the OAM to achieve near diffraction-limited lateral resolution of 0.5 μm at 532nm. The all-optical OAM provides several benefits over current piezoelectric detector-based systems, such as increased lateral and axial resolution, higher sensitivity, robustness, and potentially more compatibility with multimodal instruments.

  9. Thermal properties of carbon nanowall layers measured by a pulsed photothermal technique

    NASA Astrophysics Data System (ADS)

    Achour, A.; Belkerk, B. E.; Ait Aissa, K.; Vizireanu, S.; Gautron, E.; Carette, M.; Jouan, P.-Y.; Dinescu, G.; Brizoual, L. Le; Scudeller, Y.; Djouadi, M.-A.

    2013-02-01

    We report the thermal properties of carbon nanowall layers produced by expanding beam radio-frequency plasma. The thermal properties of carbon nanowalls, grown at 600 °C on aluminium nitride thin-film sputtered on fused silica, were measured with a pulsed photo-thermal technique. The apparent thermal conductivity of the carbon at room temperature was found to increase from 20 to 80 Wm-1 K-1 while the thickness varied from 700 to 4300 nm, respectively. The intrinsic thermal conductivity of the carbon nanowalls attained 300 Wm-1 K-1 while the boundary thermal resistance with the aluminium nitride was 3.6 × 10-8 Km2 W-1. These results identify carbon nanowalls as promising material for thermal management applications.

  10. Small-body deflection techniques using spacecraft: Techniques in simulating the fate of ejecta

    NASA Astrophysics Data System (ADS)

    Schwartz, Stephen R.; Yu, Yang; Michel, Patrick; Jutzi, Martin

    2016-04-01

    We define a set of procedures to numerically study the fate of ejecta produced by the impact of an artificial projectile with the aim of deflecting an asteroid. Here we develop a simplified, idealized model of impact conditions that can be adapted to fit the details of specific deflection-test scenarios, such as what is being proposed for the AIDA project. Ongoing studies based upon the methodology described here can be used to inform observational strategies and safety conditions for an observing spacecraft. To account for ejecta evolution, the numerical strategies we are employing are varied and include a large N-Body component, a smoothed-particle hydrodynamics (SPH) component, and an application of impactor scaling laws. Simulations that use SPH-derived initial conditions show high-speed ejecta escaping at low angles of inclination, and very slowly moving ejecta lofting off the surface at higher inclination angles, some of which reimpacts the small-body surface. We are currently investigating the realism of this and other models' behaviors. Next steps will include the addition of solar perturbations to the model and applying the protocol developed here directly to specific potential mission concepts such as the proposed AIDA scenario.

  11. Photothermal Spectroscopy Applied to Environmental Monitoring

    NASA Astrophysics Data System (ADS)

    Ofori-Boadu, George; Peterson, K. M.; Hommerich, U. H.

    1999-11-01

    Increasing pollution of waters and soil has become an important social and economical issue. There is an urgent need for simple, compact and inexpensive techniques for quantitative identification of trace levels of pollutants such as phosphate, iron, etc. We are currently engaged in the development of a laser based technique to measure pollutants in water or soil solution. The approach we use is to measure weak absorption of pollutants using photothermal deflection spectroscopy(PDS) and then compare results with existing methods. PDS is a pump probe technique. A pump laser is used to optically excite the sample. A fraction of absorbed light is released as heat, which induces a change in refractive index. Subsequently, a probe laser passing through the heated area will be deflected depending on the amount of absorbed light. Initial results of applying PDS to measure small concentrations of iron and phosphate in water solutions will be presented at the conference.

  12. Measurement of Thermal Properties of Triticale Starch Films Using Photothermal Techniques

    NASA Astrophysics Data System (ADS)

    Correa-Pacheco, Z. N.; Cruz-Orea, A.; Jiménez-Pérez, J. L.; Solorzano-Ojeda, S. C.; Tramón-Pregnan, C. L.

    2015-06-01

    Nowadays, several commercially biodegradable materials have been developed with mechanical properties similar to those of conventional petrochemical-based polymers. These materials are made from renewable sources such as starch, cellulose, corn, and molasses, being very attractive for numerous applications in the plastics, food, and paper industries, among others. Starches from maize, rice, wheat, and potato are used in the food industry. However, other types of starches are not used due to their low protein content, such as triticale. In this study, starch films, processed using a single screw extruder with different compositions, were thermally and structurally characterized. The thermal diffusivity, thermal effusivity, and thermal conductivity of the biodegradable films were determined using photothermal techniques. The thermal diffusivity was measured using the open photoacoustic cell technique, and the thermal effusivity was obtained by the photopyroelectric technique in an inverse configuration. The results showed differences in thermal properties for the films. Also, the films microstructures were observed by scanning electron microscopy, transmission electron microscopy, and the crystalline structure determined by X-ray diffraction.

  13. Thermal conductivity of PVD TiAlN films using pulsed photothermal reflectance technique

    NASA Astrophysics Data System (ADS)

    Ding, Xing-Zhao; Samani, M. K.; Chen, George

    2010-11-01

    In the present work, we have measured thermal-conductivity of industrial thin film TiAlN with a thickness of around 3 μm. These films are used in machining industry for cutting tools in order to increase their service life. A series of TiAlN coating with a different Al/Ti atomic ratio were deposited on Fe-304 stainless steel (AISI304) substrate by a lateral rotating cathode arc process. The samples were then coated with a 0.8 μm gold layer on top by magnetron sputtering. We present the thermal-conductivity measurement of these samples using pulsed photothermal reflectance (PPR) technique at room temperature. The thermal conductivity of the pure TiN coating is about 11.9 W/mK. A significant decrease in thermal conductivity was found with increasing Al/Ti atomic ratio. A minimum thermal conductivity of about 4.63 W/mK was obtained at the Al/Ti atomic ratio of around 0.72.

  14. Vapor concentration measurement with photothermal deflectometry

    NASA Technical Reports Server (NTRS)

    Banish, R. Michael; Xiao, Rong-Fu; Rosenberger, Franz

    1988-01-01

    Theoretical and experimental results for using the photothermal deflection technique to measure vapor species concentration, while minimizing the disturbance of the transport (material) parameters due to vapor heating, are developed and described. In contrast to common practice, the above constraints require using a pump-beam duty cycle of less than 50 percent. The theoretical description of the shortened heating time is based on a step-function formulation of the pumping cycle. The results are obtained as closed-form solutions of the energy equation for many chopping cycles until steady state is reached, by use of a Green's-function method. The Euler formulation of the Fermat principle is used to calculate the deflection angle. The equations are expanded to include the effects of vapor velocity on both the temperature and temperature gradient profiles. The effects of finite (unfocused) pump and probe beams and thermal (Soret) diffusion are also accounted for. Excellent agreement between theory and experiment is obtained.

  15. Across-plane thermal characterization of films based on amplitude-frequency profile in photothermal technique

    SciTech Connect

    Xu, Shen; Wang, Xinwei

    2014-10-15

    This work develops an amplitude method for the photothermal (PT) technique to analyze the amplitude of the thermal radiation signal from the surface of a multilayered film sample. The thermal conductivity of any individual layer in the sample can be thereby determined. Chemical vapor deposited SiC film samples (sample 1 to 3: 2.5 to 3.5 μm thickness) with different ratios of Si to C and thermally oxidized SiO{sub 2} film (500 nm thickness) on silicon substrates are studied using the amplitude method. The determined thermal conductivity based on the amplitude method is 3.58, 3.59, and 2.59 W/m⋅K for sample 1 to 3 with ±10% uncertainty. These results are verified by the phase shift method, and sound agreement is obtained. The measured thermal conductivity (k) of SiC is much lower than the value of bulk SiC. The large k reduction is caused by the structure difference revealed by Raman spectroscopy. For the SiO{sub 2} film, the thermal conductivity is measured to be 1.68 ± 0.17 W/m⋅K, a little higher than that obtained by the phase shift method: 1.31 ± 0.06 W/m⋅K. Sensitivity analysis of thermal conductivity and interfacial resistance is conducted for the amplitude method. Its weak-sensitivity to the thermal contact resistance, enables the amplitude method to determine the thermal conductivity of a film sample with little effect from the interface thermal resistance between the film and substrate. The normalized amplitude ratio at a high frequency to that at a low frequency provides a reliable way to evaluate the effusivity ratio of the film to that of the substrate.

  16. Influence of immediate dentin sealing techniques on cuspal deflection and fracture resistance of teeth restored with composite resin inlays.

    PubMed

    Oliveira, L; Mota, E G; Borges, G A; Burnett, L H; Spohr, A M

    2014-01-01

    SUMMARY This research evaluated the influence of immediate dentin sealing (IDS) techniques on cuspal deflection and fracture resistance of teeth restored with composite resin inlays. Forty-eight maxillary premolars were divided into four groups: G1, sound teeth (control); G2, without IDS; G3, IDS with Clearfil SE Bond (CSE); and G4, IDS with CSE and Protect Liner F. The teeth from groups 2, 3, and 4 received mesio-distal-occlusal preparations. The impressions were made with vinyl polysiloxane, followed by provisional restoration and storage in water for seven days. The impressions were poured using type IV die stone, and inlays with Filtek Z250 composite resin were built over each cast. The inlays were luted with Panavia F. After storage in water for 72 hours, a 200-N load was applied on the occlusal surface using a metal sphere connected to a universal testing machine, and the cuspal deflection was measured with a micrometer. The specimens were then submitted to an axial load until failure. The following mean cuspal deflection (μm) and mean fracture resistance (N) followed by the same lowercase letter represent no statistical difference by analysis of variance and Tukey (p<0.05): cuspal deflection: G1, 3.1 ± 1.5(a); G2, 10.3 ± 4.6(b); G3, 5.5 ± 1.8(ac); and G4, 7.7 ± 5.1(bc); fracture resistance: G1, 1974 ± 708(a); G2, 1162 ± 474(b); G3, 700 ± 280(b); and G4, 810 ± 343(b). IDS with CSE allowed cuspal deflection comparable with that associated with sound teeth. The application of Protect Liner F did not contribute to a decrease in cuspal deflection. The IDS techniques did not influence the fracture resistance of teeth. PMID:23718211

  17. The Deflection Plate Analyzer: A Technique for Space Plasma Measurements Under Highly Disturbed Conditions

    NASA Technical Reports Server (NTRS)

    Wright, Kenneth H., Jr.; Dutton, Ken; Martinez, Nelson; Smith, Dennis; Stone, Nobie H.

    2003-01-01

    A technique has been developed to measure the characteristics of space plasmas under highly disturbed conditions; e.g., non-Maxwellian plasmas with strong drifting populations and plasmas contaminated by spacecraft outgassing. The present method is an extension of the capabilities of the Differential Ion Flux Probe (DIFP) to include a mass measurement that does not include either high voltage or contamination sensitive devices such as channeltron electron multipliers or microchannel plates. This reduces the complexity and expense of instrument fabrication, testing, and integration of flight hardware as compared to classical mass analyzers. The new instrument design is called the Deflection Plate Analyzer (DPA) and can deconvolve multiple ion streams and analyze each stream for ion flux intensity (density), velocity (including direction of motion), mass, and temperature (or energy distribution). The basic functionality of the DPA is discussed. The performance characteristics of a flight instrument as built for an electrodynamic tether mission, the Propulsive Small Expendable Deployer System (ProSEDS), and the instrument s role in measuring key experimental conditions are also discussed.

  18. The Deflection Plate Analyzer: A Technique for Space Plasma Measurements Under Highly Disturbed Conditions

    NASA Technical Reports Server (NTRS)

    Wright, Kenneth H., Jr.; Dutton, Ken; Martinez, Nelson; Smith, Dennis; Stone, Nobie H.

    2004-01-01

    A technique has been developed to measure the characteristics of space plasmas under highly disturbed conditions; e.g., non-Maxwellian plasmas with strong drifting populations and plasmas contaminated by spacecraft outgassing. The present method is an extension of the capabilities of the Differential Ion Flux Probe (DIFP) to include a mass measurement that does not include either high voltage or contamination sensitive devices such as channeltron electron multipliers or microchannel plates. This reduces the complexity and expense of instrument fabrication, testing, and integration of flight hardware as compared to classical mass analyzers. The new instrument design is called the Deflection Plate Analyzer (DPA) and can deconvolve multiple ion streams and analyze each stream for ion flux intensity (density), velocity (including direction of motion), mass, and temperature (or energy distribution). The basic functionality of the DPA is discussed. The performance characteristics of a flight instrument as built for an electrodynamic tether mission, the Propulsive Small Expendable Deployer System (ProSEDS), and the instrument s role in measuring key experimental conditions are also discussed.

  19. Deflecting Shearpin

    NASA Technical Reports Server (NTRS)

    Gregory, Peyton B.

    1993-01-01

    Spring loading helps prevent permanent deformation of adjacent bearing surfaces. Shearpin deflects as load compresses inner spring. Maximum deflection determined by gap between halves of capture ring. Beyond deflection, pin acts as standard shearpin.

  20. Simulation and Prototype Design of Variable Step Angle Techniques Based Asteroid Deflection for Future Planetary Mission

    NASA Astrophysics Data System (ADS)

    Sathiyavel, C.

    2016-07-01

    Asteroids are minor planets, especially those of the inner Solar System. The most desirable asteroids for cross the geo-synchronous orbit are the carbonaceous C-type asteroids that are deemed by the astronomy community to have a planetary protection categorization of unrestricted Earth return. The mass of near earth Asteroids (assuming spherical asteroid) as a function of its diameter varies from 2 m to 10m, the corresponding densities from 1.9/cm3 to 3.8 g/cm3. For example, a 6.5-m diameter asteroid with a density of 2.8 g/cm3 has a mass of order 4,00,000 kg. If this Asteroid falls on earth then the earth will be destroyed at when the equally of inclination angle both of earth and Asteroid. My proposed work is how we can avert this great danger for near feature the above mass of Asteroid. The present work is Simulation and Prototype Design of a Variable Step Angle Techniques Based Asteroid Deflection for future planetary Mission. Proposed method is comparing with previous method that will be very useful to achieving hit the ion velocity to asteroid surface in several direction at static position of Asteroid deviate mission[ADM].The deviate angle α1 to α2 with help of Variable step angle techniques, it is containing Stepper Motor with attach of Ion propulsion module system.VASAT module is locating the top edge on the three axis stabilized Method in ADM.The three axis stabilized method is including the devices are like Gyroscope sensor ,Arduino Microcontroller system and ion propulsion techniques. Arduino Microcontroller system determines the orientation from gyroscope sensor. Then it uses ion Propulsion techniques modules to control the required motion like pitch, yaw and roll attitude of the ADM. The exhaust thrust value is 1500 mN and velocity is 10,000 m/s [from simulation results but experimental output results is small because low quality of Components is used in research lab] .The propulsion techniques also used as a static position of ADM Mission [both

  1. Photothermal single particle Rutherford scattering microscopy.

    PubMed

    Selmke, Markus; Cichos, Frank

    2013-03-01

    We demonstrate that the quantum-mechanical description of Rutherford scattering has a photonic counterpart in a new form of single particle photothermal microscopy. Using a split detector we provide experimental evidence that photons are deflected by a photothermal potential that is created by a local refractive index change around a heated nanoparticle. The deflection experienced is shown to be the analog to the deflection of a massive particle wave packet in unscreened spinless Coulomb scattering. The experimentally found focal detection geometry reveals a lateral split feature which will allow new correlation-based velocimetry experiments of absorbing particles with ultrahigh sensitivity. PMID:23521256

  2. Depth profiling of thermophysical parameters of curved solids using photothermal technique

    NASA Astrophysics Data System (ADS)

    Wang, Chinhua; Liu, Liwang; Chen, Zhuying; Yuan, Xiao

    2010-03-01

    The effect of curved surface of both cylindrical and spherical samples with continuous gradient structure (e.g., case hardened surface) on the photothermal radiometric signal(PTR) are investigated. Using an appropriate signal processing, it is found theoretically that the curvature effect of both cylindrical and spherical samples can be, or partially can be suppressed under certain conditions and the PTR signal from the curved composite sample can be equivalent to that of a flat surface with the same structure.

  3. Thermal diffusivity measurement by lock-in photothermal shadowgraph method

    NASA Astrophysics Data System (ADS)

    Cifuentes, A.; Alvarado, S.; Cabrera, H.; Calderón, A.; Marín, E.

    2016-04-01

    Here, we present a novel application of the shadowgraph technique for obtaining the thermal diffusivity of an opaque solid sample, inspired by the orthogonal skimming photothermal beam deflection technique. This new variant utilizes the shadow projected by the sample when put against a collimated light source. The sample is then heated periodically by another light beam, giving rise to thermal waves, which propagate across it and through its surroundings. Changes in the refractive index of the surrounding media due to the heating distort the shadow. This phenomenon is recorded and lock-in amplified in order to determine the sample's thermal diffusivity.

  4. Hardness depth profiling of case hardened steels using a three-dimensional photothermal technique

    NASA Astrophysics Data System (ADS)

    Qu, Hong; Wang, Chinhua; Guo, Xinxin; Mandelis, Andreas

    2010-03-01

    A method of retrieving thermophysical depth profiles of continuously inhomogeneous materials is presented both theoretically and experimentally using the three-dimensional (3-D) photothermal radiometry. A 3-D theoretical model suitable for characterizing solids with arbitrary continuously varying thermophysical property depth profiles and finite (collimated or focused) laser beam spotsize is developed. A numerical fitting algorithm to retrieve the thermophysical profile was demonstrated with three case hardened steel samples. The reconstructed thermal conductivity depth profiles were found to be well anti-correlated with microhardness profiles obtained with the conventional indenter method.

  5. Characterization of acoustic effects on flame structures by beam deflection technique

    SciTech Connect

    Bedat, B.; Kostiuk, L.W.; Cheng, R.K.

    1993-10-01

    This work shows that the acoustic effects are the causes of the small amplitude flame wrinkling and movements seen in all the different gravitational conditions. The comparison between the acoustic velocity and beam deflection spectra for the two conditions studied (glass beads and fiber glass) demonstrates clearly this flame/acoustic coupling. This acoustic study shows that the burner behaves like a Helmholtz resonator. The estimated resonance frequency corresponds well to the experimental measurements. The fiber glass damps the level of the resonance frequency and the flame motion. The changes shown in normalized beam deflection spectra give further support of this damping. This work demonstrates that the acoustics has a direct influence on flame structure in the laminar case and the preliminary results in turbulent case also show a strong coupling. The nature of this flame/acoustic coupling are still not well understood. Further investigation should include determining the frequency limits and the sensitivity of the flame to acoustic perturbations.

  6. Photothermal techniques applied to the determination of the water vapor diffusion coefficient and thermal diffusivity of edible films.

    PubMed

    Aguilar-Mendez, M A; Martin-Martinez, E San; Morales, J E; Cruz-Orea, A; Jaime-Fonseca, M R

    2007-04-01

    Water vapor diffusion coefficient (WVDC) and thermal diffusivity (alpha) were determined in gelatin-starch films through photothermal techniques. The effect of different variables in the elaboration of these films, such as starch and glycerol concentrations and pH, were evaluated through the response surface methodology. The results indicated that an increase in the glycerol concentration and pH favored the WVDC of the films. On the other hand, alpha was influenced principally by the starch content and pH of the film-forming solution. The minimum alpha value was 4.5 x 10(-4) cm2/s, which is compared with alpha values reported for commercial synthetic polymers. PMID:17420552

  7. A study of model deflection measurement techniques applicable within the national transonic facility

    NASA Technical Reports Server (NTRS)

    Hildebrand, B. P.; Doty, J. L.

    1982-01-01

    Moire contouring, scanning interferometry, and holographic contouring were examined to determine their practicality and potential to meet performance requirements for a model deflection sensor. The system envisioned is to be nonintrusive, and is to be capable of mapping or contouring the surface of a 1-meter by 1-meter model with a resolution of 50 to 100 points. The available literature was surveyed, and computations and analyses were performed to establish specific performance requirements, as well as the capabilities and limitations of such a sensor within the geometry of the NTF section test section. Of the three systems examined, holographic contouring offers the most promise. Unlike Moire, it is not hampered by limited contour spacing and extraneous fringes. Its transverse resolution can far exceed the limited point sampling resolution of scanning heterodyne interferometry. The availability of the ruby laser as a high power, pulsed, multiple wavelength source makes such a system feasible within the NTF.

  8. Nanoscale Characterization of Organometal Trihalide Perovskite using Photothermal Induced Resonance (PTIR) Technique

    NASA Astrophysics Data System (ADS)

    Chae, Jungseok; Centrone, Andrea; Yuan, Yongbo; Shao, Yuchuan; Wang, Qi; Xiao, Zhengguo; Dong, Qingfeng; Huang, Jinsong

    Further improvement of the performance of organometal trihalide perovskites (OTP) solar cells can be aided by nanoscale characterization. Photothermal induced resonance (PTIR), is a novel scanning probe method that enable measuring vibrational and electronic absorption maps and spectra with a resolution as high as 20 nm. In this presentation, the chemical composition and bandgap of OTP thin films was characterized with PTIR: 1) to identify the origin of the switchable photovoltaic effect and 2) to quantify the local chloride content in mixed-halide perovskites. PTIR vibrational maps recorded in correspondence of methyl ammonium ions (MA +) for a as prepared lateral structure solar cell were uniform but displayed stronger intensity in proximity of the cathode after electric poling. Those measurements provide the first direct proof of ion electron migration in OTP devices. Because chloride incorporation modifies the bandgap in MAPbI3-xClx perovskites, PTIR electronic maps and spectra were used to extract the local chloride content as a function of annealing. Results show that the as-prepared sample consist of a mixture of Cl-rich and Cl-poor phases that evolves into a homogenous Cl-poorer phase upon annealing. This measurement suggests that Cl- is progressively expelled from the film.

  9. Investigation of Lamb Waves Propagation by Fibre-Coupling Optical Beam Deflection Detection Technique and Finite Element Method

    NASA Astrophysics Data System (ADS)

    Chen, Xiao; Xu, Bo-qiang; Xu, Rong-qing; Shen, Zhong-hua; Lu, Jian; Ni, Xiao-wu

    2004-02-01

    Measurement of laser-generated transient Lamb waves propagation has been performed in 0.25 mm-thick iron plate by using a fibre sensor based on optical beam deflection technique. The detection principle of this optical method is discussed in detail. A high-powered Q-switched Nd:YAG laser was used to excite Lamb waves on the polished surface of iron plate. The well-defined Lamb waveforms, as well as their properties of oscillation and dispersion are presented in this paper. Furthermore, according to the ablation model, the development and propagation of Lamb waves are numerical simulated by the finite element method that has been widely used in laser ultrasonic field. The experimental results show good agreement with the numerical simulation. Therefore, this optical detection technique has considerable potential in ultrasonic field.

  10. Photothermal imaging in 3D surface analysis of membrane drug delivery.

    PubMed

    Gotter, B; Faubel, W; Neubert, R H H

    2010-01-01

    Various methods exist for research into the penetration process in the human nail plate and for investigation of dermal drug delivery. Application of spectroscopic methods in this scientific field is gaining importance. However, no method meets all demands of the large variety of applications. An alternative optical technique for the characterisation of samples is the photothermal spectroscopy. Photoacoustic techniques, photothermal radiometry, and photothermal beam deflection spectroscopy (PDS) are non-destructive analytical techniques that take advantage of the so-called photoacoustic and photothermal phenomena. PDS, in conjunction with an appropriate scanner, allows for depth profiling and is a promising technique for studies of three-dimensional drug diffusion into artificial and biological membranes. The objective of this article is to demonstrate the use of PDS imaging for pharmaceutical applications and drug delivery studies, with two experiments being used as examples: the follow-up of lateral dithranol penetration into an artificial membrane and depth-resolved measurement of the distribution of a model drug within a keratin membrane from bovine hoof. PMID:19482081

  11. Residual stress in sputtered gold films on quartz measured by the cantilever beam deflection technique.

    PubMed

    Thornell, G; Ericson, F; Hedlund, C; Ohrmaim, J; Schweitz, J A; Portnoff, G

    1999-01-01

    With resonator applications in mind, the residual stress in sputtered gold electrodes on quartz has been investigated with respect to various deposition rates (2, 10, and 50 A/s), pressures (1.0 and 3.0 10(-3) mbar), deposition temperatures (80 degrees C and room temperature (RT)), film thicknesses (approx. 400 to 800 A), and substrate smoothnesses (lapped and polished), using the cantilever beam deflection method. Samples were monitored for 4 weeks at room temperature followed by 13 weeks of annealing at 85 degrees C. The initial stress (ranging from -180 to -60 MPa) was compressive for all samples but turned tensile (a few megaPascals) in some of the samples after annealing. A significant decrease in initial compressive stress appeared with samples coated at an elevated temperature. From samples prepared at lower pressure and differing only in film thickness and substrate roughness, an increased compressive stress was found in thicker films and on rougher surfaces. The stress relaxation has been fitted to an exponential expression, and an attempt to relate the stress to a frequency shift (typically a few parts per million for ordinary, 100-mum thick AT blanks) has been made. With the help of transmission electron microscopy (TEM) the film morphology was investigated and related to the deposition parameters and aging. Judging from the increase in compressive stress and grain refinement with increased deposition rate and decreased pressure, the atomic peening mechanism is the most likely reason for the induced stress. Rutherford backscattering spectrometry (RBS) was employed to rule out the inclusion of argon (below or around 0.5%) as an explanation. From the vague, but clearly discernible, trend toward faster RT stress relaxation with higher initial stress, together with the finer film morphology, the relief mechanism is believed to be stress-promoted grain boundary diffusion. PMID:18238503

  12. Inspection of an end quenched 0.15%-0.2% C, 0.6%-0.9% Mn steel jominy bar with photothermal radiometric techniques

    NASA Astrophysics Data System (ADS)

    Liu, Yue; Baddour, Natalie; Mandelis, Andreas; Wang, Chinhua

    2004-08-01

    The effect of the cooling rate on hardness and thermal conductivity in a metallurgical Jominy bar made of 0.15%-0.2% C, 0.6%-0.9% Mn (AISI 1018) steel, by means of a water end-quenched heat treatment process without diffusion-controlled case depth, is studied with photothermal radiometry (PTR). It is concluded that our two PTR techniques, common-mode rejection demodulation and conventional 50% duty-cycle square-wave frequency scan, are sensitive to low hardness values and gradients, unlike the high values all previous photothermal studies have dealt with to-date. Both PTR methods have yielded an anticorrelation between thermal conductivity and microhardness in this case as in previous cases with heat-treated and diffusion-controlled case depth profiles. It is shown that the cooling rate strongly affects both hardness and thermal conductivity in the Jominy-bar heat-treating process.

  13. Quantum efficiency and metastable lifetime measurements in solid state laser materials via lock-in rate-window photothermal radiometry: Technique and application to ruby (Cr[sup 3+]:Al[sub 2]O[sub 3])

    SciTech Connect

    Mandelis, A.; Chen, Zhuo-Hui; Bleiss, R. )

    1993-09-01

    The newly developed photothermal detection technique of rate-window infrared radiometry is applied to the measurement of the metastable state deexcitation parameters of a ruby laser rod. The technique employs a square laser pulse and monitors the infrared photothermal radiometric response of the sample. By applying the photothermal lock-in rate-window concept, the radiative lifetime and quantum efficiency of Cr[sup 3+]:Al[sub 2]O[sub 3] are measured with optimal SNR and simple, unambiguous interpretation from the extremum in the lock-in analyzer in-phase rate-window signal. This technique simplifies significantly the experimental methodology; optimizes the photothermal SNR, which is inherently low in conventional frequency or time-domain photothermal measurements; and offers extended measurement dynamic range for both radiative quantum efficiency and lifetime in laser materials, as compared to frequency-scanned harmonic detection. Therefore, rate-window infrared photothermal radiometry may prove a valuable tool for the combined measurement of metastable lifetime and nonradiative energy conversion efficiency in laser materials with fast deexcitation rates.

  14. Photothermal laser speckle imaging

    PubMed Central

    Regan, Caitlin; Ramirez-San-Juan, Julio C.; Choi, Bernard

    2014-01-01

    The analysis of speckle contrast in a time-integrated speckle pattern enables visualization of superficial blood flow in exposed vasculature, a method we call laser speckle imaging (LSI). With current methods, LSI does not enable visualization of subsurface or small vasculature, because of optical scattering by stationary structures. In this work we propose a new technique called photothermal LSI to improve the visualization of blood vessels. A 595 nm laser pulse was used to excite blood in both in vitro and in vivo samples. The high absorption coefficient of blood at this wavelength results in efficient conversion of optical energy to thermal energy, resulting in an increase in the local temperature and hence increased scatterer motion, and thus a transient decrease in speckle contrast. As a result, we found that photothermal LSI was able to visualize blood vessels that were hidden when imaged with a conventional LSI system. PMID:25166060

  15. Photothermal Techniques Applied to the Thermal Characterization of l-Cysteine Nanofluids

    NASA Astrophysics Data System (ADS)

    Alvarado, E. Maldonado; Ramón-Gallegos, E.; Jiménez Pérez, J. L.; Cruz-Orea, A.; Hernández Rosas, J.

    2013-05-01

    Thermal-diffusivity ( D) and thermal-effusivity ( e) measurements were carried out in l-cysteine nanoliquids l-cysteine in combination with Au nanoparticles and protoporphyrin IX (PpIX) nanofluid) by using thermal lens spectrometry (TLS) and photopyroelectric (PPE) techniques. The TLS technique was used in the two mismatched mode experimental configuration to obtain the thermal-diffusivity of the samples. On the other hand, the sample thermal effusivity ( e) was obtained by using the PPE technique where the temperature variation of a sample, exposed to modulated radiation, is measured with a pyrolectric sensor. From the obtained thermal-diffusivity and thermal-effusivity values, the thermal conductivity and specific heat capacity of the sample were calculated. The obtained thermal parameters were compared with the thermal parameters of water. The results of this study could be applied to the detection of tumors by using the l-cysteine in combination with Au nanoparticles and PpIX nanofluid, called conjugated in this study.

  16. Thermal characterization of a liquid resin for 3D printing using photothermal techniques

    NASA Astrophysics Data System (ADS)

    Jiménez-Pérez, José L.; Pincel, Pavel Vieyra; Cruz-Orea, Alfredo; Correa-Pacheco, Zormy N.

    2016-05-01

    Thermal properties of a liquid resin were studied by thermal lens spectrometry (TLS) and open photoacoustic cell (OPC), respectively. In the case of the TLS technique, the two mismatched mode experimental configuration was used with a He-Ne laser, as a probe beam and an Argon laser was used as the excitation source. The characteristic time constant of the transient thermal lens was obtained by fitting the theoretical expression to the experimental data in order to obtain the thermal diffusivity ( α) of the resin. On the other hand, the sample thermal effusivity ( e) was obtained by using the OPC technique. In this technique, an Argon laser was used as the excitation source and was operated at 514 nm with an output power of 30 mW. From the obtained thermal diffusivity ( α) and thermal effusivity ( e) values, the thermal conductivity ( k) and specific heat capacity per unit volume ( ρc) of resin were calculated through the relationships k = e( α)1/2 and ρc = e/( α)1/2. The obtained thermal parameters were compared with the thermal parameters of the literature. To our knowledge, the thermal characterization of resin has not been reported until now. The present study has applications in laser stereo-lithography to manufacture 3D printing pieces.

  17. REVIEW: Application of laser photothermal spectroscopy for standoff detection of trace explosive residues on surfaces

    NASA Astrophysics Data System (ADS)

    Skvortsov, L. A.; Maksimov, E. M.

    2010-09-01

    Laser photothermal methods of standoff detection of trace explosive residues on surfaces are considered. The analysis is restricted to the most promising methods: photoacoustic spectroscopy, deflection spectroscopy, and IR photothermal imaging of objects under resonant irradiation. Particular attention is paid to the choice of radiation sources and detectors. Comparative analysis of the existing standoff detection methods for explosive particles on the object surface is performed. Prospects of laser photothermal spectroscopy in this field are discussed.

  18. Application of laser photothermal spectroscopy for standoff detection of trace explosive residues on surfaces

    SciTech Connect

    Skvortsov, L A; Maksimov, E M

    2010-09-10

    Laser photothermal methods of standoff detection of trace explosive residues on surfaces are considered. The analysis is restricted to the most promising methods: photoacoustic spectroscopy, deflection spectroscopy, and IR photothermal imaging of objects under resonant irradiation. Particular attention is paid to the choice of radiation sources and detectors. Comparative analysis of the existing standoff detection methods for explosive particles on the object surface is performed. Prospects of laser photothermal spectroscopy in this field are discussed. (review)

  19. Absorption of Low-Loss Optical Materials Measured at 1064 nm by a Position-Modulated Collinear Photothermal Detection Technique

    NASA Astrophysics Data System (ADS)

    Loriette, Vincent; Boccara, Claude

    2003-02-01

    A collinear photothermal detection bench is described that makes use of a position-modulated heating source instead of the classic power-modulated source. This new modulation scheme increases by almost a factor 2 the sensitivity of a standard mirage bench. This bench is then used to measure the absorption coefficient of OH-free synthetic fused silica at 1064 nm in the parts per 106 range, which, combined with spectrophotometric measurements, confirms that the dominant absorption source is the OH content.

  20. Atomic oxygen damage characterization by photothermal scanning

    NASA Technical Reports Server (NTRS)

    Williams, A. W.; Wood, N. J.; Zakaria, A. B.

    1993-01-01

    In this paper we use a photothermal imaging technique to characterize the damage caused to an imperfectly coated gold-coated Kapton sample exposed to successively increased fluences of atomic oxygen in a laboratory atomic source.

  1. Absorption of low-loss optical materials measured at 1064 nm by a position-modulated collinear photothermal detection technique.

    PubMed

    Loriette, Vincent; Boccara, Claude

    2003-02-01

    A collinear photothermal detection bench is described that makes use of a position-modulated heating source instead of the classic power-modulated source. This new modulation scheme increases by almost a factor 2 the sensitivity of a standard mirage bench. This bench is then used to measure the absorption coefficient of OH-free synthetic fused silica at 1064 nm in the parts per 10(6) range, which, combined with spectrophotometric measurements, confirms that the dominant absorption source is the OH content. PMID:12564484

  2. Measurement of diffusion and thermal diffusion in ternary fluid mixtures using a two-color optical beam deflection technique

    NASA Astrophysics Data System (ADS)

    Königer, A.; Wunderlich, H.; Köhler, W.

    2010-05-01

    We have developed a highly sensitive two-color beam deflection setup to measure diffusion and thermal diffusion in ternary fluid mixtures following a suggestion of Haugen and Firoozabadi [J. Phys. Chem. B 110, 17678 (2006)]. Simultaneous detection of two laser beams with different wavelengths makes it possible to determine the time dependent concentration profiles of all three components. By comparing the measured beam deflection signals to a numerical solution of the coupled heat and mass transport equations, the diffusion matrix, the thermal diffusion, and the Soret coefficients are obtained by a numerical model combined with a nonlinear least-squares fitting routine. The results can be improved by additional thermal diffusion forced Rayleigh scattering experiments, which yield a contrast-weighted average thermal diffusion coefficient. The three Soret coefficients can be obtained independently from the stationary beam deflection amplitudes. Measurements have been performed on the symmetric (equal weight fractions) ternary mixtures dodecane/isobutylbenzene/1,2,3,4-tetrahydronaphthalene and 1-methylnaphthalene/octane/decane. There is only partial agreement between our results and literature data.

  3. Temperature-dependent thermal characterization of Ge2Sb2Te5 and related interfaces by the photothermal radiometry technique

    NASA Astrophysics Data System (ADS)

    Battaglia, Jean-Luc; Cappella, Andrea; Varesi, Enrico; Schick, Vincent; Kusiak, Andrzej; Wiemer, Claudia; longo, Massimo; Gotti, Andrea; Hay, Bruno

    2010-03-01

    The thermal conductivity of Ge2Sb2Te5 (GST) layers, as well as the thermal boundary resistance at the interface between the GST and amorphous SiO2, were measured using a PhotoThermal Radiometry experiment. The two phase-changes of the Ge2Sb2Te5 were retrieved, starting from the amorphous and sweeping to the fcc crystalline state at 130 °C and then to the hcp crystalline state at 310 °C. The thermal conductivity resulted to be constant in the amorphous phase, whereas it evolved between the two crystalline states. The thermal boundary resistance at the GST-SiO2 interface was estimated to be higher for the hcp phase than for the amorphous and fcc ones.

  4. Experimental study of novel microactuator based on photothermal expansion

    NASA Astrophysics Data System (ADS)

    Liu, Chao; Zhang, Dong-Xian; Zhang, Hai-Jun

    2008-03-01

    A novel photothermal drive method was proposed. A novel photothermal micro-actuator (PTA) was developed with this method. We introduced the deflection mechanism of the asymmetric expansive arms with different widths. When a beam of infrared laser irradiates the arms, the different increase temperature and photothermal expansion controlled by the different rates of specific surface area cause a magnified lateral deflection. A prototyping micro-actuator of 1000 μm length was manufactured by using an excimer laser micromachining system, and using polypropylene material. Experiments have been carried out to check the feasibility of deflection, with a laser diode (650 nm) as the external power source to activate the micro-actuator. The results show that the actuator can practically generate an obvious lateral deflection without considering the size or the location of the irradiated light spot strictly. The deflection status of the micro-actuator could be controlled remotely from 0 μm to 14.33 μm by changing the laser power from 0 mW to 10 mW. This kind of novel PTA is quite simple and convenient for operation. It will be quite useful for the applications in the fields of micro/nano-technology and with large displacement/actuation force and remote controlling.

  5. Photothermal and photoacoustic methods for mapping surface absorbance: Adaptation for screening chemical and biomolecular libraries

    NASA Astrophysics Data System (ADS)

    Koebel, Matthias M.

    Photoacoustic and photothermal methods are useful tools for the analysis of solid state samples and thin films. Both techniques may be used to study surface absorber distributions on surfaces. In the photoacoustic experiment, light absorption at a solid/air interface launches a pressure wave which propagates through the air. The acoustic wave is detected by deflection of a probe laser beam. For non-parallel orientation of the probe beam with respect to the sample surface, acoustic waves launched from individual absorber features travel different distances before they intersect with the probe beam. This allows temporal encoding of the spatial distribution of surface absorbers. An experimental demonstration of this novel photoacoustic of detection scheme is presented. In the photothermal experiment, detection is based on production of a temperature change at the sample surface following light absorption. Thermal diffusion generates temperature gradients in the solid sample and the adjacent fluid layer. The resulting refractive index gradient in the adjacent fluid medium is measured by deflection of a probe laser beam. Using the transverse photothermal deflection spectroscopy (t-PDS) method, two dimensional absorber distribution maps of a flat sample surface can be recorded. A number of colored thin polymer film are used to characterize the sensitivity in air and a value of 7.5 · 10-6 W is found. Gold nanoparticles are excellent optical absorber labels for biological and biochemical binding assays. The synthesis and characterization of gold nanoparticles of different sizes and surface chemical functionalities is presented. A novel readout method for protein microarrays based on photothermal detection of nanoparticle labeled proteins is described. Protein microarrays are developed with functionalized gold nanoparticles and analyzed using t-PDS. The observed coloration intensity performance depends on the intrinsic nature of the target protein. Neutravidin produces the

  6. Truncated-correlation photothermal coherence tomography for deep subsurface analysis

    NASA Astrophysics Data System (ADS)

    Kaiplavil, Sreekumar; Mandelis, Andreas

    2014-08-01

    Photothermal diffusion-wave imaging is a promising technique for the analysis of a range of media. However, traditional diffusion-wave techniques are limited by the physics of parabolic diffusion and can only produce depth-integrated planar images. Here, we report a depth-resolved photothermal imaging modality, henceforth termed truncated-correlation photothermal coherence tomography (TC-PCT). This enables three-dimensional visualization of subsurface features, which is not possible with known optical or photothermal imaging techniques. Examples include imaging of solids with intricate subsurface structures and discontinuities, such as holes in steel, burn depth profiles in tissues, and the structure of bone. It is compatible with regulations concerning maximum permissible exposure and is the photothermal analogue of optical coherence tomography. Axial and lateral resolutions in bone are measured to be ~25 and 100 µm, respectively, with a depth range of ~3.2 mm (approximately four thermal diffusion lengths).

  7. Photothermal Effect and Heat Dissipation in a Micromechanical Resonator

    NASA Astrophysics Data System (ADS)

    Kim, Dae Hwan; Lee, Eun Joong; Cho, Myung Rae; Kim, Chul Sung; Park, Yun Daniel; Kouh, Taejoon

    2012-07-01

    We describe the photothermal effect in an aluminium-silicon nitride doubly-clamped beam with an optical deflection scheme. Incident optical power results in the temperature rise in the composite beam and the shift in the resonance frequency due to thermal stress. The observed dynamic response is consistent with the detailed beam equation as well as the thermal conduction model. The pressure-dependent dynamics of the beam allows the investigation of convective heat dissipation due to the surrounding gas molecules as well as determination of heat transfer coefficient. The photothermally coupled operation presented here opens up the prospects for miniaturized pressure-sensing elements.

  8. Noncontact measurement of angular deflection

    NASA Technical Reports Server (NTRS)

    Bryant, E. L.

    1978-01-01

    Technique for measuring instantaneous angular deflection of object requires no physical contact. Technique utilizes two flat refractors, converging lens, and different photocell. Distinction of method is its combination of optical and electromechanical components into feedback system in which measurement error is made to approach zero. Application is foreseen in measurement of torsional strain.

  9. Laser speckle imaging based on photothermally driven convection

    NASA Astrophysics Data System (ADS)

    Regan, Caitlin; Choi, Bernard

    2016-02-01

    Laser speckle imaging (LSI) is an interferometric technique that provides information about the relative speed of moving scatterers in a sample. Photothermal LSI overcomes limitations in depth resolution faced by conventional LSI by incorporating an excitation pulse to target absorption by hemoglobin within the vascular network. Here we present results from experiments designed to determine the mechanism by which photothermal LSI decreases speckle contrast. We measured the impact of mechanical properties on speckle contrast, as well as the spatiotemporal temperature dynamics and bulk convective motion occurring during photothermal LSI. Our collective data strongly support the hypothesis that photothermal LSI achieves a transient reduction in speckle contrast due to bulk motion associated with thermally driven convection. The ability of photothermal LSI to image structures below a scattering medium may have important preclinical and clinical applications.

  10. Laser Photothermal Analysis of Magnetoelectric Materials

    NASA Astrophysics Data System (ADS)

    Penchev, S.; Pencheva, V.; Nedkov, I.; Kutzarova, T.; Naboko, V.

    2010-01-01

    Modulated optical reflectance (MOR) technique of laser photothermal analysis is implemented to magnetoresistive La0,7Sr0,3MnO3 (LSMO) thin film. The sensor signal is based on the measurement of the variations of optical reflectivity of the sample subjected to periodic photothermal modulation. Assuming Drude model, it is proportional to the variations of the charge carrier concentration. The optical setup is mounted as a flexible laser microscope, based on elements of integral and fibre optics. The noncontact, nondestructive measurement scheme is prospective for applications to structural analysis and characterization of new magnetic and magnetoelectric materials for the next generation electronic devices.

  11. Frequency domain photothermal radiometry with spherical solids

    SciTech Connect

    Wang, Chinhua; Liu, Yue; Mandelis, Andreas; Shen, Jun

    2007-04-15

    Motivated by increasing practical and industrial applications of photothermal techniques in the measurement of materials of various shapes with curvature, we extend the applications of photothermal diagnostics to solid spheres, in which both theoretical and experimental photothermal radiometry studies on spherical geometries and thermal diffusivity of the sample are discussed. Based on the Green function method, a full thermal-wave field distribution of a spherical solid is obtained. The characteristics of the thermal-wave field with respect to thermophysical properties of the material, the diameter of the solid, the size of the incident laser beam, and the measurement angle are discussed. Experimental results with steel spheres of different diameters exhibit good agreement between the theory and the experiments.

  12. Application of Photothermal Techniques in the Determination of the Water-Vapor Diffusion Coefficient and Thermal Effusivity of Hydrogels

    NASA Astrophysics Data System (ADS)

    Raymundo-Ortiz, A. I.; Ramos-Ramirez, E. G.; Cruz-Orea, A.; Salazar-Montoya, J. A.

    2013-09-01

    The main objective of this work is to determine the effect of different sodium alginate concentrations in hydrogels on their water-vapor diffusion coefficient (WVDC) and thermal effusivity (. These physical parameters were measured by photoacoustic and pyroelectric techniques, respectively. The results indicate that the higher values for the WVDC are presented at a concentration of 2 % sodium alginate. At lower concentrations of sodium alginate, the sample thermal effusivity increases, with a value close to the water thermal effusivity.

  13. Determination of the thermophysical parameters of Zn1-xBexSe mixed crystals by means of photothermal techniques

    NASA Astrophysics Data System (ADS)

    Zakrzewski, J.; Maliski, M.; Pawlak, M.; Firszt, F.; Gowski, S.; McZyska, H.; Strzakowski, K.

    2006-03-01

    This paper presents the results of the studies of a thermal diffusivity of a series of mixed Zn1-xBexSe crystals by means of the piezoelectric technique. For determination of a thermal diffusivity of samples the method based on the measurement of the phase of the piezoelectric signal, in the rear configuration, as a function of a frequency of modulation was chosen. This method enabled analysis of the influence of Be concentration and the process of annealing of crystals on the values of their thermal diffusivities.

  14. Microwave Deflection Sensor

    NASA Technical Reports Server (NTRS)

    Shores, Paul; Kobayashi, Herb; Ngo, Phong; Lichtenberg, C. L.

    1988-01-01

    Doppler-radar instrument measures small deflections or vibrations of reflecting surface. Acting as interferometric micrometer, instrument includes combination of analog and digital circuits measuring change in phase of radar return due to movement of reflecting surface along signal-propagation path. Includes homodyne Doppler-radar transceiver and digital signal-processing circuitry to measure change in phase shift as target deflects.

  15. Photothermal lesions in soft tissue induced by optical fiber microheaters.

    PubMed

    Pimentel-Domínguez, Reinher; Moreno-Álvarez, Paola; Hautefeuille, Mathieu; Chavarría, Anahí; Hernández-Cordero, Juan

    2016-04-01

    Photothermal therapy has shown to be a promising technique for local treatment of tumors. However, the main challenge for this technique is the availability of localized heat sources to minimize thermal damage in the surrounding healthy tissue. In this work, we demonstrate the use of optical fiber microheaters for inducing thermal lesions in soft tissue. The proposed devices incorporate carbon nanotubes or gold nanolayers on the tips of optical fibers for enhanced photothermal effects and heating of ex vivo biological tissues. We report preliminary results of small size photothermal lesions induced on mice liver tissues. The morphology of the resulting lesions shows that optical fiber microheaters may render useful for delivering highly localized heat for photothermal therapy. PMID:27446642

  16. Photothermal lesions in soft tissue induced by optical fiber microheaters

    PubMed Central

    Pimentel-Domínguez, Reinher; Moreno-Álvarez, Paola; Hautefeuille, Mathieu; Chavarría, Anahí; Hernández-Cordero, Juan

    2016-01-01

    Photothermal therapy has shown to be a promising technique for local treatment of tumors. However, the main challenge for this technique is the availability of localized heat sources to minimize thermal damage in the surrounding healthy tissue. In this work, we demonstrate the use of optical fiber microheaters for inducing thermal lesions in soft tissue. The proposed devices incorporate carbon nanotubes or gold nanolayers on the tips of optical fibers for enhanced photothermal effects and heating of ex vivo biological tissues. We report preliminary results of small size photothermal lesions induced on mice liver tissues. The morphology of the resulting lesions shows that optical fiber microheaters may render useful for delivering highly localized heat for photothermal therapy. PMID:27446642

  17. Dynamic photothermal-mechanical response of a microcantilever modified by carbon nanotube film.

    PubMed

    Lin, Cheng; Zhu, Yong

    2016-03-20

    Dynamic photothermal-mechanical response of a tri-material microcantilever illuminated by an intensity modulated laser source is theoretically analyzed using the heat dynamic differential model and finite element model based on the COMSOL 5.0. Tri-material microcantilever samples are fabricated by transferring carbon nanotube film onto a silicon microcantilever with aluminum coating. During the experiment, these samples are illuminated by an intensity-modulated laser pulse, and the maximum photothermal response frequency is ∼173  Hz. Experimental results are consistent with theoretical analyses. The photothermal spectroscopy detection of water vapor in the open environment is carried out, and the linear correlation coefficient between spectroscopy signal and water concentration is 0.997. Experimental results demonstrated the feasibility of tri-material microcantilever as a thermal sensor for photothermal deflection spectroscopy. PMID:27140569

  18. Photothermal imaging of melanin

    NASA Astrophysics Data System (ADS)

    Kerimo, Josef; DiMarzio, Charles A.

    2013-02-01

    We present photothermal images of melanin using modulation with two laser beams. Strong melanin absorption followed by efficient nonradiative relaxation caused heating and an increase in temperature. This temperature effect was used as an imaging contrast to detect melanin. Melanin from several samples including Sepia officinalis, black human hair, and live zebra fish, were imaged with a high signal-to-noise ratio. For the imaging, we focused two near infrared laser beams (pump and probe) collinearly with different wavelengths and the pump was modulated in amplitude. The thermally induced variations in the refractive index, at the modulation frequency, were detected by the scattering of the probe beam. The Photothermal method brings several imaging benefits including the lack of background interference and the possibility of imaging for an extended period of time without photodamage to the melanin. The dependence of the photothermal signal on the laser power, modulation frequency, and spatial offset of the probe is discussed. The new photothermal imaging method is promising and provides background-free and label-free imaging of melanin and can be implemented with low-cost CW lasers.

  19. All-optical beam deflection method for simultaneous thermal conductivity and thermo-optic coefficient ( d n / d T ) measurements

    NASA Astrophysics Data System (ADS)

    Putnam, Shawn A.; Fairchild, Steven B.; Arends, Armando A.; Urbas, Augustine M.

    2016-05-01

    This work describes an all-optical beam deflection method to simultaneously measure the thermal conductivity ( Λ) and thermo-optic coefficient ( d n / d T ) of materials that are absorbing at λ = 10.6 μm and are transparent to semi-transparent at λ = 632.8 nm. The technique is based on the principle of measuring the beam deflection of a probe beam (632.8 nm) in the frequency-domain due to a spatially and temporally varying index gradient that is thermally induced by 50:50 split pump beam from a CO2 laser (10.6 μm). The technique and analysis methods are validated with measurements of 10 different optical materials having Λ and d n / d T properties ranging between 0.7 W/m K ≲ Λ ≲ 33.5 W/m K and -12 × 10-6 K-1 ≲ d n / d T ≲ 14 × 10-6 K-1, respectively. The described beam deflection technique is highly related to other well-established, all-optical materials characterization methods, namely, thermal lensing and photothermal deflection spectroscopy. Likewise, due to its all-optical, pump-probe nature, it is applicable to materials characterization in extreme environments with minimal errors due to black-body radiation. In addition, the measurement principle can be extended over a broad range of electromagnetic wavelengths (e.g., ultraviolet to THz) provided the required sources, detectors, and focusing elements are available.

  20. Long Range Nanoparticle Surface Energy Transfer Ruler for Monitoring Photothermal Therapy Response

    PubMed Central

    Singh, Anant K.; Lu, Wentong; Senapati, Dulal; Khan, Sadia Afrin; Fan, Zhen; Senapati, Tapas; Demeritte, Teresa; Beqa, Lule; Ray, Paresh Chandra

    2012-01-01

    Gold nanotechnology driven recent approach opens up a new possibility for the destruction of cancer cells through photothermal therapy. Ultimately, photothermal therapy may enter into clinical therapy and as a result, there is an urgent need for techniques to monitor on time tumor response to therapy. Driven by the need, in this article we report nanoparticle surface energy transfer (NSET) approach to monitor photothermal therapy process by measuring the simple fluorescence intensity change. Florescence intensity change is due to the light-controlled photothermal release of ssDNA/RNA via dehybridization during therapy process. Our time dependent results show that just by monitoring fluorescence intensity change, one can monitor photothermal therapy response during therapy process. Possible mechanism and operating principle of our NSET assay have been discussed. Ultimately, this NSET assay could have enormous potential applications in rapid, on-site monitoring of photothermal therapy process, which is critical to providing effective treatment of cancer and MDRB infections. PMID:21744496

  1. Combined photothermal lens and photothermal mirror characterization of polymers.

    PubMed

    Aréstegui, Odon S; Poma, Patricia Y N; Herculano, Leandro S; Lukasievicz, Gustavo V B; Guimarães, Francine B; Malacarne, Luis C; Baesso, Mauro L; Bialkowski, Stephen E; Astrath, Nelson G C

    2014-01-01

    We propose a combined thermal lens and thermal mirror method as concurrent photothermal techniques for the physical characterization of polymers. This combined method is used to investigate polymers as a function of temperature from room temperature up to 170 °C. The method permits a direct determination of thermal diffusivity and thermal conductivity. Additional measurements of specific heat, linear thermal expansion, and temperature-dependent optical path change are also performed. A complete set of thermal, optical, and mechanical properties of polycarbonate and poly (methyl methacrylate) samples are obtained. Methods presented here can be useful for in situ characterization of semitransparent materials, where fast and non-contacting measurements are required. PMID:25014843

  2. Photothermal microscopy for studying the role of nano-sized absorbing precursors in laser-induced damage of optical materials

    NASA Astrophysics Data System (ADS)

    Commandré, M.; Natoli, J.-Y.; Gallais, L.

    2008-01-01

    Laser-induced damage in optical components has long been acknowledged as a localized phenomenon linked to the presence of defects. Destructive investigations combined to optical characterizations have led to the conclusion that in high quality components the damage initiators are typically a few nanometers in size and have low densities. The understanding of damage phenomena requires the development of non destructive evaluation techniques with both high spatial resolution and sensitivity to detect these defects. In this context, a High Resolution Photothermal Deflection microscope (HRPD) has been developed and coupled with a damage facility at the same wavelength 1.064 μm. The behavior under irradiation of model defects such as gold inclusions (3 to 250 nm) has been studied. We show how HRPD gives determining information about damage mechanisms.

  3. Optical measurement of unducted fan blade deflections

    NASA Technical Reports Server (NTRS)

    Kurkov, Anatole P.

    1988-01-01

    A nonintrusive optical method for measuring unducted fan (or propeller) blade deflections is described and evaluated. The measurement does not depend on blade surface reflectivity. Deflection of a point at the leading edge and a point at the trailing edge in a plane nearly perpendicular to the pitch axis is obtained with a single light beam generated by a low-power, helium-neon laser. Quantitiative analyses are performed from taped signals on a digital computer. Averaging techniques are employed to reduce random errors. Measured static deflections from a series of high-speed wind tunnel tests of a counterrotating unducted fan model are compared with available, predicted deflections, which are also used to evaluate systematic errors.

  4. Optical measurement of propeller blade deflections

    NASA Technical Reports Server (NTRS)

    Kurkov, Anatole P.

    1988-01-01

    A nonintrusive optical method for measurement of propeller blade deflections is described and evaluated. It does not depend on the reflectivity of the blade surface but only on its opaqueness. Deflection of a point at the leading edge and a point at the trailing edge in a plane nearly perpendicular to the pitch axis is obtained using a single light beam generated by a low-power helium-neon laser. Quantitative analyses are performed from taped signals on a digital computer. Averaging techniques are employed to reduce random errors. Measured deflections from a static and a high-speed test are compared with available predicted deflections which are also used to evaluate systematic errors.

  5. Photothermal degradation studies of encapsulants

    NASA Technical Reports Server (NTRS)

    Liang, R. H.

    1984-01-01

    The reliability physics program at JPL is outlined. The overall objectives and approaches are given in the program. The objectives, approaches and conclusions are given for two specific parts of the programs. These two parts are mechanistic studies of photothermal degradation and performance characteristics of materials with respect to photothermal stresses.

  6. Application of photoacoustic, photothermal and fluorescence spectroscopies in signal enhancement and the kinetics, chemistry and photophysics of several dyes

    SciTech Connect

    Isak, S.J.

    1992-06-01

    Modified photoacoustic and photothermal spectroscopies are applied in analytical studies of liquid and solid systems. Quenching of benzophenone by potassium iodide is used to demonstrate application of time resolved photothermal spectroscopies in study of fast (submicrosecond) deexcitation processes. Inherently weak X-ray photoacoustic signals at a synchrotron are enhanced by the introduction of a volatile liquid into a gas-microphone photoacoustic cell. Traditionally, photoacoustic signals have been detected either by gas coupling with a microphone or with a piezoelectric detector. However, optically detected photoacoustic signals have been used in the determination of physical properties of a liquid sample system and are successfully applied to the study of deexcitation processes of a number of dye molecules. Photothermal beam deflection photoacoustic (PBDPA), fluorescence and absorbance measurements are utilized to study the chemistry and photophysics of cresyl violet in aqueous, aqueous micellar and methanolic solutions. A concentration dependence of the fluorescence quantum yield of cresyl violet is investigated. Aspects of chemistry and photophysics relating to potential use of several diazo dyes as photothermal sensitizing dyes in photodynamic therapy are explored experimentally and discussed. Photothermal beam deflection, fluorescence and absorbance measurements are again utilized. The dyes are found to have a number of interesting chemical and photophysical properties. They are also determined to be ideal photothermal sensitizing dye candidates.

  7. Recent progress in photothermally-based spectroscopies

    SciTech Connect

    Amer, N.M.

    1981-09-01

    The major objective is to exploit novel optical heating schemes for the ultrasensitive (e.g., parts per trillion), unambiguous, and relatively simple characterization of effluents produced during energy production and utilization. The physcial principle underlying these detection schemes is that when a beam of electromagnetic radiation is absorbed by a given medium (gas, liquid, solid, or aerosol), heating will ensue. The heat is what we employ to measure very low optical absorption coefficients (approx. 10/sup -10/ cm/sup -1/). This is accomplished in one of three ways: (a) optical heating will cause a rise in pressure which can be detected with a suitable transducer, e.g., a microphone. This type of spectroscopy is known as photoacoustic; (b) optical heating causes a corresponding modulation of the index of refraction of the absorbing material which can be used to deflect a weak laser probe beam propogating through the material. The amplitude and phase of the deflection is quantitatively related to the absorption coefficient; or (c) in the case of solids, heating will cause deformation of the sample which can be detected, for example, interferometrically and related to the optical absorption coefficients. A brief summary of recent results in photothermal spectroscopies is given.

  8. Deflection Sensors Utilizing Optical Multi-Stability

    NASA Astrophysics Data System (ADS)

    Shehadeh, Shadi H.; Cada, Michael; Qasymeh, Montasir; Ma, Yuan

    2010-06-01

    Deflection sensors have attracted significant attention due to their wide application in pressure and temperature measurements in practical systems. Several techniques have been proposed, studied, and tested to realize optical deflection sensor elements, including Mach-Zehnder (MZI), and Fabry-Pérot interferometers. In this work, a novel optical deflection sensor that is comprised of two cascaded optical resonators is proposed and analyzed. The proposed structure is designed to operate in the multi-stable (input to output) regime. As the first resonator is equipped with a movable mirror, which is connected to a diaphragm in order to sense changes in deflection, the second resonator is filled with non-linear material. It is demonstrated that such a structure has a novel memory property, aside from having the ability to yield instant deflection measurements. This novel property is attributed to the non-linear refractive index of the medium of the second resonator. Furthermore, the sensor sensitivity (which is the ratio of the change in the output light intensity to the change in the induced deflection) is enhanced due to the input-output multi-stable behavior of the proposed structure. This device possesses a promising potential for applications in future smart sensors.

  9. Dynamic pavement deflection

    NASA Astrophysics Data System (ADS)

    Rand, D. W.; Jacobs, K. M.

    1981-06-01

    Dynamic pavement deflection measurements for bituminous concrete pavements of two and three-quarter, five and seven-eights, and seven and one-half inches in thickness under moving axle loads of 15,000, 18,000, and 22,000 pounds were obtained at speeds of 10, 25 and 45 miles per hour. The results were analyzed and compared to Benkelman beam measurements. The data indicate that slow moving loads have greater adverse effect (larger deflections) on the pavement than the high speed loads. The results also show that the bituminous pavement undergoes numerous vertical fluctuations and bending as the front and rear axles approached the point of measurement. The magnitude of the vertical displacement was measured via the means of an accelerometer and double integrator. When values of the dynamic deflections were in the magnitude of 0.07 through 0.10 inches, there was evidence of pavement failure. When the deflection values were above 0.10 inches pavement failures were distinct.

  10. A new deflection technique applied to an existing scheme of electrostatic accelerator for high energy neutral beam injection in fusion reactor devices

    NASA Astrophysics Data System (ADS)

    Pilan, N.; Antoni, V.; De Lorenzi, A.; Chitarin, G.; Veltri, P.; Sartori, E.

    2016-02-01

    A scheme of a neutral beam injector (NBI), based on electrostatic acceleration and magneto-static deflection of negative ions, is proposed and analyzed in terms of feasibility and performance. The scheme is based on the deflection of a high energy (2 MeV) and high current (some tens of amperes) negative ion beam by a large magnetic deflector placed between the Beam Source (BS) and the neutralizer. This scheme has the potential of solving two key issues, which at present limit the applicability of a NBI to a fusion reactor: the maximum achievable acceleration voltage and the direct exposure of the BS to the flux of neutrons and radiation coming from the fusion reactor. In order to solve these two issues, a magnetic deflector is proposed to screen the BS from direct exposure to radiation and neutrons so that the voltage insulation between the electrostatic accelerator and the grounded vessel can be enhanced by using compressed SF6 instead of vacuum so that the negative ions can be accelerated at energies higher than 1 MeV. By solving the beam transport with different magnetic deflector properties, an optimum scheme has been found which is shown to be effective to guarantee both the steering effect and the beam aiming.

  11. A new deflection technique applied to an existing scheme of electrostatic accelerator for high energy neutral beam injection in fusion reactor devices.

    PubMed

    Pilan, N; Antoni, V; De Lorenzi, A; Chitarin, G; Veltri, P; Sartori, E

    2016-02-01

    A scheme of a neutral beam injector (NBI), based on electrostatic acceleration and magneto-static deflection of negative ions, is proposed and analyzed in terms of feasibility and performance. The scheme is based on the deflection of a high energy (2 MeV) and high current (some tens of amperes) negative ion beam by a large magnetic deflector placed between the Beam Source (BS) and the neutralizer. This scheme has the potential of solving two key issues, which at present limit the applicability of a NBI to a fusion reactor: the maximum achievable acceleration voltage and the direct exposure of the BS to the flux of neutrons and radiation coming from the fusion reactor. In order to solve these two issues, a magnetic deflector is proposed to screen the BS from direct exposure to radiation and neutrons so that the voltage insulation between the electrostatic accelerator and the grounded vessel can be enhanced by using compressed SF6 instead of vacuum so that the negative ions can be accelerated at energies higher than 1 MeV. By solving the beam transport with different magnetic deflector properties, an optimum scheme has been found which is shown to be effective to guarantee both the steering effect and the beam aiming. PMID:26932053

  12. Photothermal inactivation of bacteria on plasmonic nanostructures

    NASA Astrophysics Data System (ADS)

    Santos, Greggy M.; Ibañez de Santi Ferrara, Felipe; Zhao, Fusheng; Rodrigues, Debora F.; Shih, Wei-Chuan

    2016-03-01

    Hospital-acquired bacterial infections are frequently associated with the pathogenic biofilms on surfaces of devices and instruments used in medical procedures. The utilization of thermal plasmonic agents is an innovative approach for sterilizing hospital equipment and for in vivo therapeutic treatment of bacterial infection. A photothermal inactivation technique via array of nanoporous gold disks (NPGDs) has been developed by irradiating near infrared (NIR) light onto deposited bacterial cells (Escherichia coli, Bacillus subtilis, Exiguobacterium AT1B) on the surface of metal nanostructure. The physical and photothermal properties of the NPGD substrate were investigated using topographical scanning electron microscopy (SEM) and thermographic infrared imaging. Bacterial viability studies on NPGD substrates irradiated with and without NIR light were evaluated using a fluorescence-based two-component stain assay. The results show that the heat generated from the NPGD substrate promotes high cell death counts (~100%) at short exposure durations (<25 s) even for thermally-resistant bacterial strains. The photothermal effects on NPGD substrate can lead to point-of-care applications.

  13. OTV bearing deflection investigation

    NASA Astrophysics Data System (ADS)

    Reimer, B. L.; Diepenbrock, R. T.; Millis, M. G.

    1993-04-01

    The primary goal of the Bearing Deflectometer Investigation was to gain experience in the use of fiber optic displacement probe technology for bearing health monitoring in a liquid hydrogen turbo pump. The work specified in this Task Order was conducted in conjunction with Air Force Rocket Propulsion Laboratory Contract F04611-86-C-0010. APD conducted the analysis and design coordination to provide a displacement probe design compatible with the XLR-134 liquid hydrogen turbo pump assembly (TPA). Specifications and requirements of the bearing deflectometer were established working with Mechanical Technology Instruments, Inc. (MTI). The TPA design accommodated positioning of the probe to measure outer race cyclic deflections of the pump inlet bearing. The fiber optic sensor was installed as required in the TPA and sensor output was recorded during the TPA testing. Data review indicated that no bearing deflection signature could be differentiated from the inherent system noise. Alternate sensor installations were not investigated, but might yield different results.

  14. Viability estimation of pepper seeds using time-resolved photothermal signal characterization

    NASA Astrophysics Data System (ADS)

    Kim, Ghiseok; Kim, Geon-Hee; Lohumi, Santosh; Kang, Jum-Soon; Cho, Byoung-Kwan

    2014-11-01

    We used infrared thermal signal measurement system and photothermal signal and image reconstruction techniques for viability estimation of pepper seeds. Photothermal signals from healthy and aged seeds were measured for seven periods (24, 48, 72, 96, 120, 144, and 168 h) using an infrared camera and analyzed by a regression method. The photothermal signals were regressed using a two-term exponential decay curve with two amplitudes and two time variables (lifetime) as regression coefficients. The regression coefficients of the fitted curve showed significant differences for each seed groups, depending on the aging times. In addition, the viability of a single seed was estimated by imaging of its regression coefficient, which was reconstructed from the measured photothermal signals. The time-resolved photothermal characteristics, along with the regression coefficient images, can be used to discriminate the aged or dead pepper seeds from the healthy seeds.

  15. A novel modeling and simulation technique of photo--thermal interactions between lasers and living biological tissues undergoing multiple changes in phase.

    PubMed

    Dua, Rajan; Chakraborty, Suman

    2005-06-01

    Knowledge of heat transfer in biological bodies has many therapeutic applications involving either raising or lowering of temperature, and often requires precise monitoring of the spatial distribution of thermal histories that are produced during a treatment protocol. Extremes of temperature into the freezing and burning ranges are useful in surgical procedures for selective killing and/or removal of target tissues. For example, the primary objective of hyperthermia is to raise the temperature of the diseased tissue to a therapeutic value, typically 41- 44 degrees C, and then thermally destroy it. The present paper therefore aims to develop a mathematical model for effective simulation of photo--thermal interactions between laser rays and biological tissues. In particular, damage of biological tissues when subjected to single point laser diathermy is numerically investigated using a unique enthalpy-based approach for modeling multiple phase change, (namely, melting of fat and vaporization of water content of the tissues) and the associated release/absorption of latent heat in conjunction with unsteady state heat conduction mechanisms. The governing equations of bio-heat transfer coupled with initial and boundary conditions are solved using a finite volume approach in conjunction with line by a line tri-diagonal matrix algorithm (TDMA) solver. Temperature responses of tissues subject to laser heating are quantitatively investigated in detail using the present model, and the resultant solutions are expected to be immensely useful in a variety of Bio-thermal practices in medicine and surgery. PMID:15767117

  16. Photothermal excitation setup for a modified commercial atomic force microscope

    SciTech Connect

    Adam, Holger; Rode, Sebastian; Schreiber, Martin; Kühnle, Angelika; Kobayashi, Kei; Yamada, Hirofumi

    2014-02-15

    High-resolution imaging in liquids using frequency modulation atomic force microscopy is known to suffer from additional peaks in the resonance spectrum that are unrelated to the cantilever resonance. These unwanted peaks are caused by acoustic modes of the liquid and the setup arising from the indirect oscillation excitation by a piezoelectric transducer. Photothermal excitation has been identified as a suitable method for exciting the cantilever in a direct manner. Here, we present a simple design for implementing photothermal excitation in a modified Multimode scan head from Bruker. Our approach is based on adding a few components only to keep the modifications as simple as possible and to maintain the low noise level of the original setup with a typical deflection noise density of about 15 fm/√(Hz) measured in aqueous solution. The success of the modification is illustrated by a comparison of the resonance spectra obtained with piezoelectric and photothermal excitation. The performance of the systems is demonstrated by presenting high-resolution images on bare calcite in liquid as well as organic adsorbates (Alizarin Red S) on calcite with simultaneous atomic resolution of the underlying calcite substrate.

  17. Photothermal excitation setup for a modified commercial atomic force microscope

    NASA Astrophysics Data System (ADS)

    Adam, Holger; Rode, Sebastian; Schreiber, Martin; Kobayashi, Kei; Yamada, Hirofumi; Kühnle, Angelika

    2014-02-01

    High-resolution imaging in liquids using frequency modulation atomic force microscopy is known to suffer from additional peaks in the resonance spectrum that are unrelated to the cantilever resonance. These unwanted peaks are caused by acoustic modes of the liquid and the setup arising from the indirect oscillation excitation by a piezoelectric transducer. Photothermal excitation has been identified as a suitable method for exciting the cantilever in a direct manner. Here, we present a simple design for implementing photothermal excitation in a modified Multimode scan head from Bruker. Our approach is based on adding a few components only to keep the modifications as simple as possible and to maintain the low noise level of the original setup with a typical deflection noise density of about 15 fm/sqrt{Hz} measured in aqueous solution. The success of the modification is illustrated by a comparison of the resonance spectra obtained with piezoelectric and photothermal excitation. The performance of the systems is demonstrated by presenting high-resolution images on bare calcite in liquid as well as organic adsorbates (Alizarin Red S) on calcite with simultaneous atomic resolution of the underlying calcite substrate.

  18. Advances in photo-thermal infrared imaging microspectroscopy

    NASA Astrophysics Data System (ADS)

    Furstenberg, Robert; Kendziora, Chris; Papantonakis, Michael; Nguyen, Viet; McGill, Andrew

    2013-05-01

    There is a growing need for chemical imaging techniques in many fields of science and technology: forensics, materials science, pharmaceutical and chemical industries, just to name a few. While FTIR micro-spectroscopy is commonly used, its practical resolution limit of about 20 microns or more is often insufficient. Raman micro-spectroscopy provides better spatial resolution (~1 micron), but is not always practical because of samples exhibiting fluorescence or low Raman scattering efficiency. We are developing a non-contact and non-destructive technique we call photo-thermal infrared imaging spectroscopy (PT-IRIS). It involves photo-thermal heating of the sample with a tunable quantum cascade laser and measuring the resulting increase in thermal emission with an infrared detector. Photo-thermal emission spectra resemble FTIR absorbance spectra and can be acquired in both stand-off and microscopy configurations. Furthermore, PT-IRIS allows the acquisition of absorbance-like photo-thermal spectra in a reflected geometry, suitable for field applications and for in-situ study of samples on optically IR-opaque substrates (metals, fabrics, paint, glass etc.). Conventional FTIR microscopes in reflection mode measure the reflectance spectra which are different from absorbance spectra and are usually not catalogued in FTIR spectral libraries. In this paper, we continue developing this new technique. We perform a series of numerical simulations of the laser heating of samples during photo-thermal microscopy. We develop parameterized formulas to help the user pick the appropriate laser illumination power. We also examine the influence of sample geometry on spectral signatures. Finally, we measure and compare photo-thermal and reflectance spectra for two test samples.

  19. Photothermal imaging of moving cells in lymph and blood flow in vivo

    NASA Astrophysics Data System (ADS)

    Zharov, Vladimir P.; Galanzha, Ekaterina I.; Tuchin, Valery V.

    2004-07-01

    The in vivo capabilities of a new, integrated optical system for studying lymph and blood flow were explored, including imaging of moving red and white blood cells. This system combined transmission microscopy with different dual-beam photothermal (PT) techniques, such as PT imaging, PT thermolens method, and PT deflection velocimetry. All of these PT techniques are based on irradiation of rat mesenteric microvessels with a short laser pulse and on detection of temperature-dependent variations of the refractive index with a second, probe laser beam. In general, the concept of in vivo PT flow cytometry was developed, with a focus on real-time monitoring of moving blood cells in their natural states without labeling (e.g., fluorescent), including obtaining PT images of the cells and determining their flow velocity and response to different interventions. Preliminary experiments revealed many potential applications of this integrated system: (1) quantitation of lymph and blood flow without probes; (2) imaging of moving red and white blood cells; (3) visualization and tracking of PT nanoprobes and sensitizers; (4) comparison of laser-tissue interactions in vivo and in vitro, especially optimization of laser treatment of vascular lesions (port-wine stains, lymphatic malformations, etc.); and (5) determination of the link between in vitro and in vivo cytotoxicity studies.

  20. Infrared photothermal imaging for standoff detection applications

    NASA Astrophysics Data System (ADS)

    Kendziora, C. A.; Jones, Robert M.; Furstenberg, Robert; Papantonakis, Michael; Nguyen, Viet; McGill, R. Andrew

    2012-06-01

    We are developing a technique for the stand-off detection of trace analytes and residues (explosives, hazardous chemicals, drugs, etc.) using photo-thermal infrared imaging spectroscopy (PT-IRIS). Herein, we refer to this technique as "RED" for "Remote Explosives Detection" or "Resonance Enhanced Detection". This approach leverages recent developments in critical enabling micro and nano-technology components. The first component, a compact IR quantum cascade laser (QCL), is tuned to fundamental absorption bands in the analytes and directed to illuminate a surface of interest. The second component, an IR focal plane array (FPA), is used to image the surface and detect any small increase in the thermal emission upon laser illumination. We have demonstrated the technique at up to 30 meters of stand-off distance indoors and in field tests, while operating the lasers below the eye-safe intensity limit (100 mW/cm2). In this manuscript we detail several recent improvements to the method and system, as well as some recent results for explosives on complex substrates such as car panels and fabrics. We also introduce a computational framework for modeling and simulating the optical and thermal phenomena associated with the photothermal process.

  1. Mid-infrared photothermal heterodyne spectroscopy in a liquid crystal using a quantum cascade laser

    PubMed Central

    Mërtiri, Alket; Jeys, Thomas; Liberman, Vladimir; Hong, M. K.; Mertz, Jerome; Altug, Hatice; Erramilli, Shyamsunder

    2012-01-01

    We report a technique to measure the mid-infrared photothermal response induced by a tunable quantum cascade laser in the neat liquid crystal 4-octyl-4′-cyanobiphenyl (8CB), without any intercalated dye. Heterodyne detection using a Ti:sapphire laser of the response in the solid, smectic, nematic and isotropic liquid crystal phases allows direct detection of a weak mid-infrared normal mode absorption using an inexpensive photodetector. At high pump power in the nematic phase, we observe an interesting peak splitting in the photothermal response. Tunable lasers that can access still stronger modes will facilitate photothermal heterodyne mid-infrared vibrational spectroscopy. PMID:22912508

  2. Laser induced deflection (LID) method for absolute absorption measurements of optical materials and thin films

    NASA Astrophysics Data System (ADS)

    Mühlig, Christian; Bublitz, Simon; Paa, Wolfgang

    2011-05-01

    We use optimized concepts to measure directly low absorption in optical materials and thin films at various laser wavelengths by the laser induced deflection (LID) technique. An independent absolute calibration, using electrical heaters, is applied to obtain absolute absorption data without the actual knowledge of the photo-thermal material properties. Verification of the absolute calibration is obtained by measuring different silicon samples at 633 nm where all laser light, apart from the measured reflection/scattering, is absorbed. Various experimental results for bulk materials and thin films are presented including measurements of fused silica and CaF2 at 193 nm, nonlinear crystals (LBO) for frequency conversion and AR coated fused silica for high power material processing at 1030 nm and Yb-doped silica raw materials for high power fiber lasers at 1550 nm. In particular for LBO the need of an independent calibration is demonstrated since thermal lens generation is dominated by stress-induced refractive index change which is in contrast to most of the common optical materials. The measured results are proven by numerical simulations and their influence on the measurement strategy and the obtained accuracy are shown.

  3. [Monitoring interfacial dynamics by pulsed laser techniques]. [Annual report, August 1, 1988--July 31, 1989

    SciTech Connect

    Richmond, G.

    1989-12-31

    Goal is the development and application of new optical methods to the study of dynamic processes at the electrode/electrolyte interface. The technique which was primarily focused on was second harmonic generation (SHG) because of its suitability for probing buried interfaces. A photothermal deflection spectroscopy station was also built for broad band study of the absorptivity of the interface. Dynamic processes initiated by either a fast potential step or a fast photoexcitation pulse was investigated. In the first case, metal/aqueous electrode systems were studied by time-resolved SHG. In the second, several photoactive materials of interest for solar energy devices were studied.

  4. Impeller deflection and modal finite element analysis.

    SciTech Connect

    Spencer, Nathan A.

    2013-10-01

    Deflections of an impeller due to centripetal forces are calculated using finite element analysis. The lateral, or out of plane, deflections are an important design consideration for this particular impeller because it incorporates an air bearing with critical gap tolerances. The target gap distance is approximately 10 microns at a rotational velocity of 2500 rpm. The centripetal forces acting on the impeller cause it deflect in a concave fashion, decreasing the initial gap distance as a function of radial position. This deflection is characterized for a previous and updated impeller design for comparative purposes. The impact of design options such as material selection, geometry dimensions, and operating rotational velocity are also explored, followed by a sensitivity study with these parameters bounded by specific design values. A modal analysis is also performed to calculate the impeller's natural frequencies which are desired to be avoided during operation. The finite element modeling techniques continue to be exercised by the impeller design team to address specific questions and evaluate conceptual designs, some of which are included in the Appendix.

  5. Self-sensing porphysomes for fluorescence-guided photothermal therapy.

    PubMed

    Ng, Kenneth K; Takada, Misa; Jin, Cheng C S; Zheng, Gang

    2015-02-18

    Porphysomes are highly quenched unilamellar porphyrin-lipid nanovesicles with structurally dependent photothermal properties. The high packing density of porphyrin molecules in the lipid bilayer enables their application in photothermal therapy, whereas the partial disruption of the porphysome structure over time restores the porphyrin fluorescence and enables the fluorescence-guided photothermal ablation. This conversion is a time-dependent process and cannot be easily followed using existing analytical techniques. Here we present the design of a novel self-sensing porphysome (FRETysomes) capable of fluorescently broadcasting its structural state through Förster resonance energy transfer. By doping in a near-infrared emitting fluorophore, it is possible to divert a small fraction of the absorbed energy toward fluorescence emission which provides information on whether the vesicle is intact or disrupted. Addition of bacteriopheophorbide-lipid into the vesicle bilayer as a fluorescence acceptor (0.5-7.5 mol %) yields a large separation of 100 nm between the absorption and fluorescence bands of the nanoparticle. Furthermore, a progressive increase in FRET efficiency (14.6-72.7%) is observed. Photothermal heating and serum stability in FRETysomes is comparable with the undoped porphysomes. The fluorescence arising from the energy transfer between the donor and acceptor dyes can be clearly visualized in vivo through hyperspectral imaging. By calculating the ratio between the acceptor and donor fluorescence, it is possible to determine the structural fate of the nanovesicles. We observe using this technique that tumor accumulation of structurally intact porphyrin-lipid nanovesicles persists at 24 and 48 h postinjection. The development of FRETysomes offers a unique and critical imaging tool for planning porphysome-enabled fluorescence-guided photothermal treatment, which maximizes light-induced thermal toxicity. PMID:25563975

  6. Large beam deflection using cascaded prism array

    NASA Astrophysics Data System (ADS)

    Wang, Wei-Chih; Tsui, Chi-Leung

    2012-04-01

    Endoscopes have been utilize in the medical field to observe the internals of the human body to assist the diagnosis of diseases, such as breathing disorders, internal bleeding, stomach ulcers, and urinary tract infections. Endoscopy is also utilized in the procedure of biopsy for the diagnosis of cancer. Conventional endoscopes suffer from the compromise between overall size and image quality due to the required size of the sensor for acceptable image quality. To overcome the size constraint while maintaining the capture image quality, we propose an electro-optic beam steering device based on thermal-plastic polymer, which has a small foot-print (~5mmx5mm), and can be easily fabricated using conventional hot-embossing and micro-fabrication techniques. The proposed device can be implemented as an imaging device inside endoscopes to allow reduction in the overall system size. In our previous work, a single prism design has been used to amplify the deflection generated by the index change of the thermal-plastic polymer when a voltage is applied; it yields a result of 5.6° deflection. To further amplify the deflection, a new design utilizing a cascading three-prism array has been implemented and a deflection angle to 29.2° is observed. The new design amplifies the beam deflection, while keeping the advantage of simple fabrication made possible by thermal-plastic polymer. Also, a photo-resist based collimator lens array has been added to reduce and provide collimation of the beam for high quality imaging purposes. The collimator is able to collimate the exiting beam at 4 μm diameter for up to 25mm, which potentially allows high resolution image capturing.

  7. Collagen remodeling in photo-thermal damaged skin with optical coherence tomography and multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Wu, Shu-lian; Li, Hui; Zhang, Xiao-man; Yu, Lili

    2009-08-01

    Cutaneous photo-thermal damage is the common damages in clinical medicine; it is a complex and dynamic process that follows an orderly sequence of events. The sequence can be roughly divided into three distinct, yet sequentially overlapping phases-inflammation, granulation tissue formation, and tissue remodeling. Characteristic structural changes associated with each phase could provide a basis for photo-thermal damage assessment with imaging technologies. Monitoring the skin tissue response during the skin after irradiated by laser and tracing the process of skin remodeling would help to understand the mechanism of photo-thermal. Optical coherence tomography (OCT) and multiphoton microscopy (MPM) imaging were used to observe the process of the collagen remodeling in mouse dermis photo-thermal injured which after irradiated by intense pulsed light source (IPLs) in this paper. Our finding showed that the OCT and MPM techniques can image the process of collagen remodeling in mouse dermis.

  8. Ultrasensitive Beam Deflection Measurement via Interferometric Weak Value Amplification

    SciTech Connect

    Dixon, P. Ben; Starling, David J.; Jordan, Andrew N.; Howell, John C.

    2009-05-01

    We report on the use of an interferometric weak value technique to amplify very small transverse deflections of an optical beam. By entangling the beam's transverse degrees of freedom with the which-path states of a Sagnac interferometer, it is possible to realize an optical amplifier for polarization independent deflections. The theory for the interferometric weak value amplification method is presented along with the experimental results, which are in good agreement. Of particular interest, we measured the angular deflection of a mirror down to 400{+-}200 frad and the linear travel of a piezo actuator down to 14{+-}7 fm.

  9. Calibration of a thin metal foil for infrared imaging video bolometer to estimate the spatial variation of thermal diffusivity using a photo-thermal technique

    NASA Astrophysics Data System (ADS)

    Pandya, Shwetang N.; Peterson, Byron J.; Sano, Ryuichi; Mukai, Kiyofumi; Drapiko, Evgeny A.; Alekseyev, Andrey G.; Akiyama, Tsuyoshi; Itomi, Muneji; Watanabe, Takashi

    2014-05-01

    A thin metal foil is used as a broad band radiation absorber for the InfraRed imaging Video Bolometer (IRVB), which is a vital diagnostic for studying three-dimensional radiation structures from high temperature plasmas in the Large Helical Device. The two-dimensional (2D) heat diffusion equation of the foil needs to be solved numerically to estimate the radiation falling on the foil through a pinhole geometry. The thermal, physical, and optical properties of the metal foil are among the inputs to the code besides the spatiotemporal variation of temperature, for reliable estimation of the exhaust power from the plasma illuminating the foil. The foil being very thin and of considerable size, non-uniformities in these properties need to be determined by suitable calibration procedures. The graphite spray used for increasing the surface emissivity also contributes to a change in the thermal properties. This paper discusses the application of the thermographic technique for determining the spatial variation of the effective in-plane thermal diffusivity of the thin metal foil and graphite composite. The paper also discusses the advantages of this technique in the light of limitations and drawbacks presented by other calibration techniques being practiced currently. The technique is initially applied to a material of known thickness and thermal properties for validation and finally to thin foils of gold and platinum both with two different thicknesses. It is observed that the effect of the graphite layer on the estimation of the thermal diffusivity becomes more pronounced for thinner foils and the measured values are approximately 2.5-3 times lower than the literature values. It is also observed that the percentage reduction in thermal diffusivity due to the coating is lower for high thermal diffusivity materials such as gold. This fact may also explain, albeit partially, the higher sensitivity of the platinum foil as compared to gold.

  10. Calibration of a thin metal foil for infrared imaging video bolometer to estimate the spatial variation of thermal diffusivity using a photo-thermal technique.

    PubMed

    Pandya, Shwetang N; Peterson, Byron J; Sano, Ryuichi; Mukai, Kiyofumi; Drapiko, Evgeny A; Alekseyev, Andrey G; Akiyama, Tsuyoshi; Itomi, Muneji; Watanabe, Takashi

    2014-05-01

    A thin metal foil is used as a broad band radiation absorber for the InfraRed imaging Video Bolometer (IRVB), which is a vital diagnostic for studying three-dimensional radiation structures from high temperature plasmas in the Large Helical Device. The two-dimensional (2D) heat diffusion equation of the foil needs to be solved numerically to estimate the radiation falling on the foil through a pinhole geometry. The thermal, physical, and optical properties of the metal foil are among the inputs to the code besides the spatiotemporal variation of temperature, for reliable estimation of the exhaust power from the plasma illuminating the foil. The foil being very thin and of considerable size, non-uniformities in these properties need to be determined by suitable calibration procedures. The graphite spray used for increasing the surface emissivity also contributes to a change in the thermal properties. This paper discusses the application of the thermographic technique for determining the spatial variation of the effective in-plane thermal diffusivity of the thin metal foil and graphite composite. The paper also discusses the advantages of this technique in the light of limitations and drawbacks presented by other calibration techniques being practiced currently. The technique is initially applied to a material of known thickness and thermal properties for validation and finally to thin foils of gold and platinum both with two different thicknesses. It is observed that the effect of the graphite layer on the estimation of the thermal diffusivity becomes more pronounced for thinner foils and the measured values are approximately 2.5-3 times lower than the literature values. It is also observed that the percentage reduction in thermal diffusivity due to the coating is lower for high thermal diffusivity materials such as gold. This fact may also explain, albeit partially, the higher sensitivity of the platinum foil as compared to gold. PMID:24880398

  11. Calibration of a thin metal foil for infrared imaging video bolometer to estimate the spatial variation of thermal diffusivity using a photo-thermal technique

    SciTech Connect

    Pandya, Shwetang N. Sano, Ryuichi; Peterson, Byron J.; Mukai, Kiyofumi; Akiyama, Tsuyoshi; Watanabe, Takashi; Drapiko, Evgeny A.; Alekseyev, Andrey G.; Itomi, Muneji

    2014-05-15

    A thin metal foil is used as a broad band radiation absorber for the InfraRed imaging Video Bolometer (IRVB), which is a vital diagnostic for studying three-dimensional radiation structures from high temperature plasmas in the Large Helical Device. The two-dimensional (2D) heat diffusion equation of the foil needs to be solved numerically to estimate the radiation falling on the foil through a pinhole geometry. The thermal, physical, and optical properties of the metal foil are among the inputs to the code besides the spatiotemporal variation of temperature, for reliable estimation of the exhaust power from the plasma illuminating the foil. The foil being very thin and of considerable size, non-uniformities in these properties need to be determined by suitable calibration procedures. The graphite spray used for increasing the surface emissivity also contributes to a change in the thermal properties. This paper discusses the application of the thermographic technique for determining the spatial variation of the effective in-plane thermal diffusivity of the thin metal foil and graphite composite. The paper also discusses the advantages of this technique in the light of limitations and drawbacks presented by other calibration techniques being practiced currently. The technique is initially applied to a material of known thickness and thermal properties for validation and finally to thin foils of gold and platinum both with two different thicknesses. It is observed that the effect of the graphite layer on the estimation of the thermal diffusivity becomes more pronounced for thinner foils and the measured values are approximately 2.5–3 times lower than the literature values. It is also observed that the percentage reduction in thermal diffusivity due to the coating is lower for high thermal diffusivity materials such as gold. This fact may also explain, albeit partially, the higher sensitivity of the platinum foil as compared to gold.

  12. Thermal and elastic characterizations by photothermal microscopy (invited)

    NASA Astrophysics Data System (ADS)

    Jumel, Julien; Rochais, Denis; Enguehard, Franck; Lepoutre, François

    2003-01-01

    A photothermal microscope based on photoreflectance and interferometric techniques is used to measure, on the same field, the thermal properties and the thermoelastic response of samples heated by a focused intensity modulated laser beam. In imaging mode, this instrument provides two-dimensional thermal or mechanical qualitative maps. In characterization configuration thermal and thermoelastic properties, with resolutions of a few micrometers, can be quantitatively measured if careful analysis of the signals is made.

  13. Miniaturized capillary electrophoretic drug analysis with photothermal detection

    NASA Astrophysics Data System (ADS)

    Seidel, B. S.; Faubel, W.

    1999-03-01

    A photothermal lens method is used in combination with capillary electrophoresis for detecting samples of different drugs by electrokinetic chromatography. It is for the first time that drugs (Chloramphenicol, Dichlofenac, Pentoxifyllin, Oxprenolol) are determined with thermal lens spectroscopy. Direct and indirect separation techniques are applied to various classes of substances with different characteristic absorbance spectra. The combination of capillary electrophoresis and the high sensitivity of thermal lens spectroscopy allows the analysis of nanoliter volume samples occurring in biomedical diagnostics.

  14. Highly Selective Photothermal Therapy by a Phenoxylated-Dextran-Functionalized Smart Carbon Nanotube Platform.

    PubMed

    Han, Seungmin; Kwon, Taeyun; Um, Jo-Eun; Haam, Seungjoo; Kim, Woo-Jae

    2016-05-01

    Near-infrared (NIR) photothermal therapy using biocompatible single-walled carbon nanotubes (SWNTs) is advantageous because as-produced SWNTs, without additional size control, both efficiently absorb NIR light and demonstrate high photothermal conversion efficiency. In addition, covalent attachment of receptor molecules to SWNTs can be used to specifically target infected cells. However, this technique interrupts SWNT optical properties and inevitably lowers photothermal conversion efficiency and thus remains major hurdle for SWNT applications. This paper presents a smart-targeting photothermal therapy platform for inflammatory disease using newly developed phenoxylated-dextran-functionalized SWNTs. Phenoxylated dextran is biocompatible and efficiently suspends SWNTs by noncovalent π-π stacking, thereby minimizing SWNT bundle formations and maintaining original SWNT optical properties. Furthermore, it selectively targets inflammatory macrophages by scavenger-receptor binding without any additional receptor molecules; therefore, its preparation is a simple one-step process. Herein, it is experimentally demonstrated that phenoxylated dextran-SWNTs (pD-SWNTs) are also biocompatible, selectively penetrate inflammatory macrophages over normal cells, and exhibit high photothermal conversion efficiency. Consequently, NIR laser-triggered macrophage treatment can be achieved with high accuracy by pD-SWNT without damaging receptor-free cells. These smart targeting materials can be a novel photothermal agent candidate for inflammatory disease. PMID:27029602

  15. Highly depth-resolved chirped pulse photothermal radar for bone diagnostics.

    PubMed

    Kaiplavil, Sreekumar; Mandelis, Andreas

    2011-07-01

    A novel chirped pulse photothermal (PT) radiometric radar with improved sensitivity over the conventional harmonically modulated thermal-wave radar technique and alternative pulsed laser photothermal radiometry is introduced for the diagnosis of biological samples, especially bones with tissue and skin overlayers. The constraints imposed by the laser safety (maximum permissible exposure) ceiling on pump laser energy and the strong attenuation of thermal-wave signals in tissues significantly limit the photothermally active depth in most biological specimens to a level which is normally insufficient for practical applications (a few mm below the skin surface). A theoretical approach for improvement of signal-to-noise ratio (SNR), minimizing the static (dc) component of the photothermal signal and making use of the photothermal radiometric nonlinearity has been introduced and verified by comparing the SNR of four distinct excitation wave forms (sine-wave, square-wave, constant-width and constant duty-cycle pulses) for chirping the pump laser, under constant exposure energy. At low frequencies fixed-pulsewidth chirps of large peak power were found to be superior to all other equal-energy modalities, with an SNR improvement up to two orders of magnitude. Distinct thickness-dependent characteristic delay times in a goat bone were obtained, establishing an active depth resolution range of ~2.8 mm in a layered skin-fat-bone structure, a favorable result compared to the maximum reported pulsed photothermal radiometric depth resolution <1 mm in turbid biological media. PMID:21806220

  16. Highly depth-resolved chirped pulse photothermal radar for bone diagnostics

    NASA Astrophysics Data System (ADS)

    Kaiplavil, Sreekumar; Mandelis, Andreas

    2011-07-01

    A novel chirped pulse photothermal (PT) radiometric radar with improved sensitivity over the conventional harmonically modulated thermal-wave radar technique and alternative pulsed laser photothermal radiometry is introduced for the diagnosis of biological samples, especially bones with tissue and skin overlayers. The constraints imposed by the laser safety (maximum permissible exposure) ceiling on pump laser energy and the strong attenuation of thermal-wave signals in tissues significantly limit the photothermally active depth in most biological specimens to a level which is normally insufficient for practical applications (a few mm below the skin surface). A theoretical approach for improvement of signal-to-noise ratio (SNR), minimizing the static (dc) component of the photothermal signal and making use of the photothermal radiometric nonlinearity has been introduced and verified by comparing the SNR of four distinct excitation wave forms (sine-wave, square-wave, constant-width and constant duty-cycle pulses) for chirping the pump laser, under constant exposure energy. At low frequencies fixed-pulsewidth chirps of large peak power were found to be superior to all other equal-energy modalities, with an SNR improvement up to two orders of magnitude. Distinct thickness-dependent characteristic delay times in a goat bone were obtained, establishing an active depth resolution range of ˜2.8 mm in a layered skin-fat-bone structure, a favorable result compared to the maximum reported pulsed photothermal radiometric depth resolution <1 mm in turbid biological media.

  17. Dynamic quantitative photothermal monitoring of cell death of individual human red blood cells upon glucose depletion

    NASA Astrophysics Data System (ADS)

    Vasudevan, Srivathsan; Chen, George Chung Kit; Andika, Marta; Agarwal, Shuchi; Chen, Peng; Olivo, Malini

    2010-09-01

    Red blood cells (RBCs) have been found to undergo ``programmed cell death,'' or eryptosis, and understanding this process can provide more information about apoptosis of nucleated cells. Photothermal (PT) response, a label-free photothermal noninvasive technique, is proposed as a tool to monitor the cell death process of living human RBCs upon glucose depletion. Since the physiological status of the dying cells is highly sensitive to photothermal parameters (e.g., thermal diffusivity, absorption, etc.), we applied linear PT response to continuously monitor the death mechanism of RBC when depleted of glucose. The kinetics of the assay where the cell's PT response transforms from linear to nonlinear regime is reported. In addition, quantitative monitoring was performed by extracting the relevant photothermal parameters from the PT response. Twofold increases in thermal diffusivity and size reduction were found in the linear PT response during cell death. Our results reveal that photothermal parameters change earlier than phosphatidylserine externalization (used for fluorescent studies), allowing us to detect the initial stage of eryptosis in a quantitative manner. Hence, the proposed tool, in addition to detection of eryptosis earlier than fluorescence, could also reveal physiological status of the cells through quantitative photothermal parameter extraction.

  18. Fiber-optic pulsed photothermal radiometry for fast surface-temperature measurements.

    PubMed

    Eyal, O; Scharf, V; Katzir, A

    1998-09-01

    Temperature measurement based on pulsed photothermal radiometry is described. In this technique a body is irradiated by a laser pulse and its temperature is inferred from the shape of the emitted photothermal-signal curve. A prototypical system based on a pulsed CO(2) laser, an IR detector, and IR-transmitting silver halide optical fibers was constructed and used to evaluate the feasibility of this technique. An important feature of the technique is that changes in sample emissivity or geometric factors do not introduce errors in the temperature determination. Theory, simulation, and experimental results are given and discussed. PMID:18286089

  19. Alignment of gold nanorods by angular photothermal depletion

    SciTech Connect

    Taylor, Adam B.; Chow, Timothy T. Y.; Chon, James W. M.

    2014-02-24

    In this paper, we demonstrate that a high degree of alignment can be imposed upon randomly oriented gold nanorod films by angular photothermal depletion with linearly polarized laser irradiation. The photothermal reshaping of gold nanorods is observed to follow quadratic melting model rather than the threshold melting model, which distorts the angular and spectral hole created on 2D distribution map of nanorods to be an open crater shape. We have accounted these observations to the alignment procedures and demonstrated good agreement between experiment and simulations. The use of multiple laser depletion wavelengths allowed alignment criteria over a large range of aspect ratios, achieving 80% of the rods in the target angular range. We extend the technique to demonstrate post-alignment in a multilayer of randomly oriented gold nanorod films, with arbitrary control of alignment shown across the layers. Photothermal angular depletion alignment of gold nanorods is a simple, promising post-alignment method for creating future 3D or multilayer plasmonic nanorod based devices and structures.

  20. Quantum noise in photothermal cooling

    SciTech Connect

    De Liberato, Simone; Lambert, Neill; Nori, Franco

    2011-03-15

    We study the problem of cooling a mechanical oscillator using the photothermal (bolometric) force. Contrary to previous attempts to model this system, we take into account the noise effects due to the granular nature of photon absorption. We achieve this by developing a Langevin formalism for the motion of the cantilever, valid in the bad-cavity limit, which includes both photon absorption shot noise and the noise due to radiation pressure. This allows us to tackle the cooling problem down to the noise-dominated regime and to find reasonable estimates for the lowest achievable phonon occupation in the cantilever.

  1. Photothermally induced delayed tissue death.

    PubMed

    Gordon, Jeffrey M; Shaco-Levy, Ruthy; Feuermann, Daniel; Huleihil, Mahmoud; Mizrahi, Solly

    2006-01-01

    We report pronounced delayed tissue death in photothermal surgery performed on the livers of live healthy rats with highly concentrated sunlight (ultrabright noncoherent light). Exposure times and power levels were selected to produce immediate necroses of the order of hundreds of cubic millimeters. Pathology reveals that lesion volumes increase by up to a factor of 5 within approximately 24 h after surgery, and then stabilize. Islands of viable cells can persist within damaged tissue, in the immediate vicinity of blood vessels, but also necrose within about 48 h. PMID:16822049

  2. High reflector absorptance measurements by the surface thermal lensing technique

    SciTech Connect

    Chow, R.; Taylor, J.R.; Wu, Z.L.; Krupka, R.; Yang, T.

    1996-11-01

    Surface thermal lensing is an alternate configuration of a photothermal deflection system that was used to measure low levels of optical absorption. The thermal lensing configuration facilitated the alignment of the pump and probe laser beams by using a larger diameter probe beam. This technique was applied to high performance optical coatings, specifically high reflectors at 511 nm, zero degrees angle of incidence. The absorptance of these coatings was previously measured using a high power copper vapor laser system. A high power copper laser beam is focused onto a -2 mm diameter spot. A thermal camera senses the temperature rise with respect to the rest of the coating. The temperature change, power density and beam diameter were used with an empirical formula that yields optical absorption. The surface thermal lensing technique was able to resolve absorption levels lower than that achieved with the copper laser method.

  3. AIDA: Asteroid Impact & Deflection Assessment

    NASA Astrophysics Data System (ADS)

    Cheng, A. F.; Galvez, A.; Carnelli, I.; Michel, P.; Rivkin, A.; Reed, C.

    2012-12-01

    To protect the Earth from a hazardous asteroid impact, various mitigation methods have been proposed, including deflection of the asteroid by a spacecraft impact. AIDA, consisting of two mission elements, the Double Asteroid Redirection Test (DART) and the Asteroid Impact Monitoring (AIM) mission, is a demonstration of asteroid deflection. To date, there has been no such demonstration, and there is major uncertainty in the result of a spacecraft impact onto an asteroid, that is, the amount of deflection produced by a given momentum input from the impact. This uncertainty is in part due to unknown physical properties of the asteroid surface, such as porosity and strength, and in part due to poorly understood impact physics such that the momentum carried off by ejecta is highly uncertain. A first mission to demonstrate asteroid deflection would not only be a major step towards gaining the capability to mitigate an asteroid hazard, but in addition it would return unique information on an asteroid's strength, other surface properties, and internal structure. This information return would be highly relevant to future human exploration of asteroids. We report initial results of the AIDA joint mission concept study undertaken by the Johns Hopkins Applied Physics Laboratory and ESA with support from NASA centers including Goddard, Johnson and Jet Propulsion Laboratory. For AIDA, the DART spacecraft impactor study is coordinated with an ESA study of the AIM mission, which would rendezvous with the same asteroid to measure effects of the impact. Unlike the previous Don Quijote mission study performed by ESA in 2005-2007, DART envisions an impactor spacecraft to intercept the secondary member of a binary near-Earth asteroid. DART includes ground-based observations to measure the deflection independently of the rendezvous spacecraft observations from AIM, which also measures deflection and provides detailed characterization of the target asteroid. The joint mission AIDA

  4. Elevator deflections on the icing process

    NASA Technical Reports Server (NTRS)

    Britton, Randall K.

    1990-01-01

    The effect of elevator deflection of the horizontal stabilizer for certain icing parameters is investigated. Elevator deflection can severely change the lower and upper leading-edge impingement limits, and ice can accrete on the elevator itself. Also, elevator deflection had practically no effect on the maximum local collection efficiency. It is shown that for severe icing conditions (large water droplets), elevator deflections that increase the projected height of the airfoil can significantly increase the total collection efficiency of the airfoil.

  5. The Seven Habits of Highly Deflective Colleagues

    ERIC Educational Resources Information Center

    Maher, Michelle; Chaddock, Katherine

    2009-01-01

    The authors define deflection as a strategy to bounce action or responsibility away from oneself and toward another person, time, or place. Although they contend that deflection occurs in all areas of personal and professional life, the authors limit their focus to the deflective colleague ("collega deflectivus") in academe. In this article, the…

  6. Photothermal characterization of encapsulant materials for photovoltaic modules

    NASA Technical Reports Server (NTRS)

    Liang, R. H.; Gupta, A.; Distefano, S.

    1982-01-01

    A photothermal test matrix and a low cost testing apparatus for encapsulant materials of photovoltaic modules were defined. Photothermal studies were conducted to screen and rank existing as well as future encapsulant candidate materials and/or material formulations in terms of their long term physiochemical stability under accelerated photothermal aging conditions. Photothermal characterization of six candidate pottant materials and six candidate outer cover materials were carried out. Principal products of photothermal degradation are identified. Certain critical properties are also monitored as a function of photothermal aging.

  7. Photothermal speckle modulation for noncontact materials characterization.

    PubMed

    Stolyarov, Alexander M; Sullenberger, Ryan M; Crompton, David R; Jeys, Thomas H; Saar, Brian G; Herzog, William D

    2015-12-15

    We have developed a noncontact, photothermal materials characterization method based on visible-light speckle imaging. This technique is applied to remotely measure the infrared absorption spectra of materials and to discriminate materials based on their thermal conductivities. A wavelength-tunable (7.5-8.7 μm), intensity-modulated, quantum cascade pump laser and a continuous-wave 532 nm probe laser illuminate a sample surface such that the two laser spots overlap. Surface absorption of the intensity-modulated pump laser induces a time-varying thermoelastic surface deformation, resulting in a time-varying 532 nm scattering speckle field from the surface. The speckle modulation amplitude, derived from a series of visible camera images, is found to correlate with the amplitude of the surface motion. By tuning the pump laser's wavelength over a molecular absorption feature, the amplitude spectrum of the speckle modulation is found to correlate to the IR absorption spectrum. As an example, we demonstrate this technique for spectroscopic identification of thin polymeric films. Furthermore, by adjusting the rate of modulation of the pump beam and measuring the associated modulation transfer to the visible speckle pattern, information about the thermal time constants of surface and sub-surface features can be revealed. Using this approach, we demonstrate the ability to distinguish between different materials (including metals, semiconductors, and insulators) based on differences in their thermal conductivities. PMID:26670512

  8. Copper Selenide Nanocrystals for Photothermal Therapy

    PubMed Central

    Hessel, Colin M.; Pattani, Varun; Rasch, Michael; Panthani, Matthew G.; Koo, Bonil; Tunnell, James W.; Korgel, Brian A.

    2011-01-01

    Ligand-stabilized copper selenide (Cu2−xSe) nanocrystals, approximately 16 nm in diameter, were synthesized by a colloidal hot injection method and coated with amphiphilic polymer. The nanocrystals readily disperse in water and exhibit strong near infrared (NIR) optical absorption with a high molar extinction coefficient of 7.7 × 107 cm−1 M−1 at 980 nm. When excited with 800 nm light, the Cu2−xSe nanocrystals produce significant photothermal heating with a photothermal transduction efficiency of 22%, comparable to nanorods and nanoshells of gold (Au). In vitro photothermal heating of Cu2−xSe nanocrystals in the presence of human colorectal cancer cell (HCT-116) led to cell destruction after 5 minutes of laser irradiation at 33 W/cm2, demonstrating the viabilitiy of Cu2−xSe nanocrystals for photothermal therapy applications. PMID:21553924

  9. Copper selenide nanocrystals for photothermal therapy.

    PubMed

    Hessel, Colin M; Pattani, Varun P; Rasch, Michael; Panthani, Matthew G; Koo, Bonil; Tunnell, James W; Korgel, Brian A

    2011-06-01

    Ligand-stabilized copper selenide (Cu(2-x)Se) nanocrystals, approximately 16 nm in diameter, were synthesized by a colloidal hot injection method and coated with amphiphilic polymer. The nanocrystals readily disperse in water and exhibit strong near-infrared (NIR) optical absorption with a high molar extinction coefficient of 7.7 × 10(7) cm(-1) M(-1) at 980 nm. When excited with 800 nm light, the Cu(2-x)Se nanocrystals produce significant photothermal heating with a photothermal transduction efficiency of 22%, comparable to nanorods and nanoshells of gold (Au). In vitro photothermal heating of Cu(2-x)Se nanocrystals in the presence of human colorectal cancer cell (HCT-116) led to cell destruction after 5 min of laser irradiation at 33 W/cm(2), demonstrating the viabilitiy of Cu(2-x)Se nanocrystals for photothermal therapy applications. PMID:21553924

  10. Laser photothermal diagnostics of genuine and counterfeit British and United States banknotes

    NASA Astrophysics Data System (ADS)

    Othonos, Andreas; Mandelis, Andreas; Nestoros, Marios; Christofides, Constantinos

    1997-02-01

    Laser-induced, frequency-scanned IR photothermal radiometry was used to investigate the thermophysical properties of the paper on which several genuine and counterfeit British (10 pounds) and U.S. ($DOL50, $DOL100) currency bills were printed. The radiometric photothermal amplitudes and phases were further compared with a theoretical model, which yielded simultaneous quantitative measurements of the thermal diffusivities and conductivities of the bills. Both statistical and single-specimen results demonstrated the excellent thermophysical resolution of the technique with prospects for its use in the nonintrusive, on-line identification of counterfeit banknotes.

  11. Injected current-related distortion of photothermal signals from a photovoltaic cell

    SciTech Connect

    Cahen, D.; Nordal, P.; Kanstad, S.O.

    1986-11-17

    When power dissipation in a photovoltaic cell is measured as a function of load resistance via photothermal techniques which sense only part of the photovoltaic cell, significant deviations from previously reported photoacoustic measurements can be obtained. These deviations occur under nonuniform illumination. They are due to the fact that, under these experimental conditions, the measured signal is proportional to only part of the power dissipation by injected carriers, while all of the photogenerated carriers contribute to the signal. Results from photothermal radiometry experiments are presented and explained in this way.

  12. Thickness microscopy based on photothermal radiometry for the measurement of thin films.

    PubMed

    Wang, Liping; Prekel, Helmut; Liu, Hengbiao; Deng, Yanzhuo; Hu, Jiming; Goch, Gert

    2009-03-01

    The photothermal detection technique is an innovative and non-contact method to investigate the properties of films on workpieces. This paper describes a novel experimental set-up for thickness microscopy based on photothermal radiometry. The correlation between the thermal wave signal and the film thickness is deduced and evaluated to determine the film thickness with a lateral resolution of less than 1mm. Results indicate that the thickness microscopy is a useful method to characterize thin films and has the potential to be applied in-process. PMID:19046925

  13. Improved methods for measuring thermal parameters of liquid samples using photothermal infrared radiometry

    NASA Astrophysics Data System (ADS)

    Kuriakose, Maju; Depriester, Michael; Dadarlat, Dorin; Sahraoui, Abdelhak Hadj

    2013-02-01

    High accuracy, non-contact measuring methods for finding thermal properties of liquid samples using photothermal infrared radiometry (PTR) are presented. The use of transparent windows to confine micro volume liquid samples and the implementation of front and/or back signal detection procedures helped the successful implementation of the PTR technique for measuring liquids with high proficiency. We present two configurations, the so-called back-front photothermal infrared radiometry and back photothermal infrared radiometry to find thermal diffusivity and thermal effusivity of liquid samples. Sensitivity studies and error analyses included prove the robustness of each method. As an illustration of the temperature and electric field varying studies, we have included the experimental results on a 5CB (4-cyano-4‧-pentylbiphenyl) liquid crystal.

  14. Photothermal Investigation of Micro-Uniformity Problems Caused by Different Scan Systems

    SciTech Connect

    Geiler, Hans; Brand, Klaus; Selle, Hans-Joachim

    2008-11-03

    To study beam scanning and beam profiling effects low energy implants of Boron (25 keV) and high energy implants of Helium (5.4 MeV) were carried out by use of different scanning systems including mechanical, electrostatic and hybrid scanning. The sensitivity of photothermal measurement by use of the excess carrier wave in the depth up to 50 {mu}m is proved for buried damage detection and compared with the effect in shallow damage profiles. The micro-mapping capability of the photothermal techniques allows the detection of dose variations in a sub-mm-scale without Moire effects from mapping steps. Conclusion for advanced dose monitoring by multi-frequency photothermal methods will be derived.

  15. Analysis of Photothermal Characterization of Layered Materials: Design of Optimal Experiments

    NASA Technical Reports Server (NTRS)

    Cole, Kevin D.

    2003-01-01

    In this paper numerical calculations are presented for the steady-periodic temperature in layered materials and functionally-graded materials to simulate photothermal methods for the measurement of thermal properties. No laboratory experiments were performed. The temperature is found from a new Green s function formulation which is particularly well-suited to machine calculation. The simulation method is verified by comparison with literature data for a layered material. The method is applied to a class of two-component functionally-graded materials and results for temperature and sensitivity coefficients are presented. An optimality criterion, based on the sensitivity coefficients, is used for choosing what experimental conditions will be needed for photothermal measurements to determine the spatial distribution of thermal properties. This method for optimal experiment design is completely general and may be applied to any photothermal technique and to any functionally-graded material.

  16. Apparatus to measure adsorption of condensable solvents on technical surfaces by photothermal deflection.

    PubMed

    Plimmer, M D; du Colombier, D; Iraqi Houssaini, N; Silvestri, Z; Pinot, P; Hannachi, R

    2012-11-01

    This article describes an instrument for the measurement of the mirage effect as a tool to determine the molar adsorption per unit surface area Y(1) of condensable solvents in the presence of a non-condensable carrier gas. The present apparatus is a much improved version of previous prototypes developed in our laboratory and elsewhere with a higher surface bake-out temperature (150 °C rather than 40 °C), lower residual vacuum (3 Pa versus 100 Pa), greater sample surface (40 mm diameter instead of 10 mm), more powerful optical pump beam (150 W cf. 50 W), and larger saturated vapour preparation volume (4 L instead of 1 L). The new set-up also includes the in situ monitoring of the surface via a reflected HeNe laser beam for the real-time detection of the onset of condensation. Here, we give a detailed description of the various components, outline the experimental procedure, show typical results, and suggest some straightforward improvements. PMID:23206087

  17. Apparatus to measure adsorption of condensable solvents on technical surfaces by photothermal deflection

    NASA Astrophysics Data System (ADS)

    Plimmer, M. D.; du Colombier, D.; Iraqi Houssaini, N.; Silvestri, Z.; Pinot, P.; Hannachi, R.

    2012-11-01

    This article describes an instrument for the measurement of the mirage effect as a tool to determine the molar adsorption per unit surface area Y1 of condensable solvents in the presence of a non-condensable carrier gas. The present apparatus is a much improved version of previous prototypes developed in our laboratory and elsewhere with a higher surface bake-out temperature (150 °C rather than 40 °C), lower residual vacuum (3 Pa versus 100 Pa), greater sample surface (40 mm diameter instead of 10 mm), more powerful optical pump beam (150 W cf. 50 W), and larger saturated vapour preparation volume (4 L instead of 1 L). The new set-up also includes the in situ monitoring of the surface via a reflected HeNe laser beam for the real-time detection of the onset of condensation. Here, we give a detailed description of the various components, outline the experimental procedure, show typical results, and suggest some straightforward improvements.

  18. Single laser beam photothermal microscopy

    NASA Astrophysics Data System (ADS)

    Heber, Andre; Selmke, Markus; Braun, Marco; Cichos, Frank

    2015-03-01

    Fluorescence microscopy provides a tool to study dynamics in softmatter materials on a molecular level. However, the observation time for fluorescent objects is limited due to bleaching. One way to overcome this limitation is the use of gold nanoparticles as labels. They are chemically inert under typical situations. These particles are selectively imaged using a modulated heating laser and a non-absorbed detection laser even in the presence of background scatterers. The absorbed power results in a localised temperature profile and to a refractive index change which only occurs for absorption. For finite thermal diffusivities the temperature profile does not instantly follow temperature changes present on the nanoparticle's surface. This results in an out-of-phase modulation of the detection laser. By exploiting the limited thermal diffusivity we show that a single laser beam being intensity modulated is enough to selectively image and quantify absorption. The use of a single laser makes photothermal microscopy easier to implement into existing microscopy setups.

  19. Highly Efficient Photothermal Semiconductor Nanocomposites for Photothermal Imaging of Latent Fingerprints.

    PubMed

    Cui, Jiabin; Xu, Suying; Guo, Chang; Jiang, Rui; James, Tony D; Wang, Leyu

    2015-11-17

    Optical imaging of latent fingerprints (LFPs) has been widely used in forensic science and for antiterrorist applications, but it suffers from interference from autofluorescence and the substrates background color. Cu7S4 nanoparticles (NPs), with excellent photothermal properties, were synthesized using a new strategy and then fabricated into amphiphilic nanocomposites (NCs) via polymerization of allyl mercaptan coated on Cu7S4 NPs to offer good affinities toward LFPs. Here, we develop a facile and versatile photothermal LFP imaging method based on the high photothermal conversion efficiency (52.92%, 808 nm) of Cu7S4 NCs, indicating its effectiveness for imaging LFPs left on different substrates (with various background colors), which will be extremely useful for crime scene investigations. Furthermore, by fabricating Cu7S4-CdSe@ZnS NCs, a fluorescent-photothermal dual-mode imaging strategy was used to detect trinitrotoluene (TNT) in LFPs while still maintaining a complete photothermal image of LFP. PMID:26494177

  20. Precise atomic mass measurements by deflection mass spectrometry

    NASA Astrophysics Data System (ADS)

    Barber, R. C.; Sharma, K. S.

    2003-05-01

    Since its inception nearly 90 years ago by J.J. Thomson, the precise determination of atomic masses by the classical technique of deflecting charged particles in electric and magnetic fields has provided a large body of data on naturally occurring nuclides. Currently, such measurements on stable nuclides have frequently achieved a precision of better than two parts in 10 9 of the mass. A review of the technique, together with a brief summary of the important historical developments in the field of precise atomic mass measurements, will be given. The more recent contributions to this field by the deflection mass spectrometer at the University of Manitoba will be provided as illustrations of the culmination of the techniques used and the applications that have been studied. A brief comparison between this and newer techniques using Penning traps will be presented.

  1. The Most Effective Gold Nanorod Size for Plasmonic Photothermal Therapy: Theory and In Vitro Experiments

    PubMed Central

    2015-01-01

    The development of new and improved photothermal contrast agents for the successful treatment of cancer (or other diseases) via plasmonic photothermal therapy (PPTT) is a crucial part of the application of nanotechnology in medicine. Gold nanorods (AuNRs) have been found to be the most effective photothermal contrast agents, both in vitro and in vivo. Therefore, determining the optimum AuNR size needed for applications in PPTT is of great interest. In the present work, we utilized theoretical calculations as well as experimental techniques in vitro to determine this optimum AuNR size by comparing plasmonic properties and the efficacy as photothermal contrast agents of three different sizes of AuNRs. Our theoretical calculations showed that the contribution of absorbance to the total extinction, the electric field, and the distance at which this field extends away from the nanoparticle surface all govern the effectiveness of the amount of heat these particles generate upon NIR laser irradiation. Comparing between three different AuNRs (38 × 11, 28 × 8, and 17 × 5 nm), we determined that the 28 × 8 nm AuNR is the most effective in plasmonic photothermal heat generation. These results encouraged us to carry out in vitro experiments to compare the PPTT efficacy of the different sized AuNRs. The 28 × 8 nm AuNR was found to be the most effective photothermal contrast agent for PPTT of human oral squamous cell carcinoma. This size AuNR has the best compromise between the total amount of light absorbed and the fraction of which is converted to heat. In addition, the distance at which the electric field extends from the particle surface is most ideal for this size AuNR, as it is sufficient to allow for coupling between the fields of adjacent particles in solution (i.e., particle aggregates), resulting in effective heating in solution. PMID:24433049

  2. Mechanistic interpretation of nondestructive pavement testing deflections

    NASA Astrophysics Data System (ADS)

    Hoffman, M. S.

    1980-06-01

    A method is proposed for the backcalculation of material properties in flexible pavements based on the interpretation of surface deflection measurements. ILLI-PAVE, a stress dependent finite element pavement model, was used to generate data for developing algorithms and nomographs for deflection basin interpretation. Over 11,000 deflection measurements for 24 different flexible pavement sections were collected and analyzed. Deflections were measured using the Benkelman Beam, the IDOT Road Rater, the Falling Weight Deflectometer, and an accelerometer to measure deflections under moving trucks. Loading mode effects on pavement response were investigated using dynamic and viscous pavement models. The factors controlling the pavement response to different loading modes were explained and identified. Correlations between different devices were developed. The proposed evaluation procedure is illustrated for three different flexible pavements using deflection data collected on several testing dates.

  3. Measurement of Deflection Line on Bridges

    NASA Astrophysics Data System (ADS)

    Urban, Rudolf; Štroner, Martin

    2013-12-01

    Prestressed concrete bridges are very sensitive to the increase in long-term deflections. Reliable forecasts of deflections of bridge structures during construction and durability are crucial for achieving good durability. The main results of measurements are the changes of the deflection line of the bridge structures, which places special demands on the measurement procedure. Results from measurements are very useful for the improvement of mathematical prediction methods of behaviour of long span prestressed concrete structures.

  4. Effect of the finite size of an asteroid on its deflection using a tether-ballast system

    NASA Astrophysics Data System (ADS)

    Mashayekhi, Mohammad J.; Misra, Arun K.

    2016-04-01

    Potentially hazardous near-Earth objects which can impose a significant threat on life on the planet have generated a lot of interest in the study of various asteroid deflection strategies. There are numerous asteroid deflection techniques suggested and discussed in the literature. This paper is focused on one of the non-destructive asteroid deflection strategies by attaching a long tether-ballast system to the asteroid. In the existing literature on this technique, very simplified models of the asteroid-tether-ballast system including a point mass model of the asteroid have been used. In this paper, the dynamical effect of using a finite size asteroid model on the asteroid deflection achieved is analyzed in detail. It has been shown that considering the finite size of the asteroid, instead of the point mass approximation, can have significant influence on the deflection predicted. Furthermore the effect of the tether-deployment stage, which is an essential part of any realistic asteroid deflection mission, on the predicted deflection is studied in this paper. Finally the effect of cutting the tether on the deflection achieved is analyzed and it has been shown that depending on the orbital properties of the asteroid as well as its size and rotational rate, cutting the tether at an appropriate time can increase the deflection achieved. Several numerical examples have been used in this paper to elaborate on the proposed technique and to quantitatively analyze the effect of different parameters on the asteroid deflection.

  5. Effect of the finite size of an asteroid on its deflection using a tether-ballast system

    NASA Astrophysics Data System (ADS)

    Mashayekhi, Mohammad J.; Misra, Arun K.

    2016-07-01

    Potentially hazardous near-Earth objects which can impose a significant threat on life on the planet have generated a lot of interest in the study of various asteroid deflection strategies. There are numerous asteroid deflection techniques suggested and discussed in the literature. This paper is focused on one of the non-destructive asteroid deflection strategies by attaching a long tether-ballast system to the asteroid. In the existing literature on this technique, very simplified models of the asteroid-tether-ballast system including a point mass model of the asteroid have been used. In this paper, the dynamical effect of using a finite size asteroid model on the asteroid deflection achieved is analyzed in detail. It has been shown that considering the finite size of the asteroid, instead of the point mass approximation, can have significant influence on the deflection predicted. Furthermore the effect of the tether-deployment stage, which is an essential part of any realistic asteroid deflection mission, on the predicted deflection is studied in this paper. Finally the effect of cutting the tether on the deflection achieved is analyzed and it has been shown that depending on the orbital properties of the asteroid as well as its size and rotational rate, cutting the tether at an appropriate time can increase the deflection achieved. Several numerical examples have been used in this paper to elaborate on the proposed technique and to quantitatively analyze the effect of different parameters on the asteroid deflection.

  6. Laser deflection of space objects -- An overview

    SciTech Connect

    Canavan, G.H.

    1997-04-01

    Lasers provide the two major attributes required for effective deflection of space objects: agility and efficiency. Lasers act instantaneously over long distances with little losses, but deliver energy at modest power levels. Material interceptors provide large impulses, but deliver only a fraction of the mass launched into space at low speeds. The two deflection concepts are compared, as are some important additional applications.

  7. Photothermal generation of microbubbles on plasmonic nanostructures inside microfluidic channels

    NASA Astrophysics Data System (ADS)

    Li, Jingting; Li, Ming; Santos, Greggy M.; Zhao, Fusheng; Shih, Wei-Chuan

    2016-03-01

    Microbubbles have been utilized as micro-pumps, micro-mixers, micro-valves, micro-robots and surface cleaners. Various generation techniques can be found in the literature, including resistive heating, hydrodynamic methods, illuminating patterned metal films and noble metal nanoparticles of Au or Ag. We present photothermal microbubble generation by irradiating nanoporous gold disk covered microfluidic channels. The size of the microbubble can be controlled by adjusting the laser power. The dynamics of both bubble growth and shrinkage are studied. The advantages of this technique are flexible bubble generation locations, long bubble lifetimes, no need for light-adsorbing dyes, high controllability over bubble size, low power consumption, etc. This technique has the potential to provide new flow control functions in microfluidic devices.

  8. Gold Nanoconstructs for Multimodal Diagnostic Imaging and Photothermal Cancer Therapy

    NASA Astrophysics Data System (ADS)

    Coughlin, Andrew James

    Cancer accounts for nearly 1 out of every 4 deaths in the United States, and because conventional treatments are limited by morbidity and off-target toxicities, improvements in cancer management are needed. This thesis further develops nanoparticle-assisted photothermal therapy (NAPT) as a viable treatment option for cancer patients. NAPT enables localized ablation of disease because heat generation only occurs where tissue permissive near-infrared (NIR) light and absorbing nanoparticles are combined, leaving surrounding normal tissue unharmed. Two principle approaches were investigated to improve the specificity of this technique: multimodal imaging and molecular targeting. Multimodal imaging affords the ability to guide NIR laser application for site-specific NAPT and more holistic characterization of disease by combining the advantages of several diagnostic technologies. Towards the goal of image-guided NAPT, gadolinium-conjugated gold-silica nanoshells were engineered and demonstrated to enhance imaging contrast across a range of diagnostic modes, including T1-weighted magnetic resonance imaging, X-Ray, optical coherence tomography, reflective confocal microscopy, and two-photon luminescence in vitro as well as within an animal tumor model. Additionally, the nanoparticle conjugates were shown to effectively convert NIR light to heat for applications in photothermal therapy. Therefore, the broad utility of gadolinium-nanoshells for anatomic localization of tissue lesions, molecular characterization of malignancy, and mediators of ablation was established. Molecular targeting strategies may also improve NAPT by promoting nanoparticle uptake and retention within tumors and enhancing specificity when malignant and normal tissue interdigitate. Here, ephrinA1 protein ligands were conjugated to nanoshell surfaces for particle homing to overexpressed EphA2 receptors on prostate cancer cells. In vitro, successful targeting and subsequent photothermal ablation of

  9. In vivo near-infrared photothermal therapy and computed tomography imaging of cancer cells using novel tungsten-based theranostic probe

    NASA Astrophysics Data System (ADS)

    Liu, Jianhua; Han, Jianguo; Kang, Zhichen; Golamaully, Reza; Xu, Nannan; Li, Hongpeng; Han, Xueli

    2014-05-01

    Photothermal therapy, as a physical therapeutic technique to kill cancer, has generated a great deal of interest. Photothermal agents hence play a critical role in this modern therapy. We report the use of transition metal oxides as photothermal agents based on PEGylated WO3-x nanoparticles. The well-prepared nanoparticles presented effective results during photothermal therapy both in vitro and in vivo by using near-IR laser irradiation (980 nm, 0.5 W cm-2). The tumor cells were effectively damaged using low power density during a short irradiation time without destroying healthy tissues. In vitro results of photothermal therapy with PEGylated WO3-x nanoparticles proved to be effective on 4T1 murine breast cancer cells via a confocal microscopy method and MTT assay. In vivo results were further confirmed by hematoxylin and eosin (H & E) histological staining. Additionally, PEGylated WO3-x nanoparticles were shown to be effective as a CT imaging contrast agent on a tumor-bearing mouse model. Our results suggest that this generation of PEGylated WO3-x nanoparticles can potentially be used in oncological CT imaging and photothermal therapy.Photothermal therapy, as a physical therapeutic technique to kill cancer, has generated a great deal of interest. Photothermal agents hence play a critical role in this modern therapy. We report the use of transition metal oxides as photothermal agents based on PEGylated WO3-x nanoparticles. The well-prepared nanoparticles presented effective results during photothermal therapy both in vitro and in vivo by using near-IR laser irradiation (980 nm, 0.5 W cm-2). The tumor cells were effectively damaged using low power density during a short irradiation time without destroying healthy tissues. In vitro results of photothermal therapy with PEGylated WO3-x nanoparticles proved to be effective on 4T1 murine breast cancer cells via a confocal microscopy method and MTT assay. In vivo results were further confirmed by hematoxylin and eosin

  10. Directed energy deflection laboratory measurements

    NASA Astrophysics Data System (ADS)

    Brashears, Travis; Lubin, Phillip; Hughes, Gary B.; Meinhold, Peter; Suen, Jonathan; Batliner, Payton; Motta, Caio; Griswold, Janelle; Kangas, Miikka; Johansson, Isbella; Alnawakhtha, Yusuf; Prater, Kenyon; Lang, Alex; Madajian, Jonathan

    2015-09-01

    We report on laboratory studies of the effectiveness of directed energy planetary defense as a part of the DESTAR (Directed Energy System for Targeting of Asteroids and exploRation) program. DE-STAR [1][5][6] and DE-STARLITE [2][5][6] are directed energy "stand-off" and "stand-on" programs, respectively. These systems consist of a modular array of kilowatt-class lasers powered by photovoltaics, and are capable of heating a spot on the surface of an asteroid to the point of vaporization. Mass ejection, as a plume of evaporated material, creates a reactionary thrust capable of diverting the asteroid's orbit. In a series of papers, we have developed a theoretical basis and described numerical simulations for determining the thrust produced by material evaporating from the surface of an asteroid [1][2][3][4][5][6]. In the DE-STAR concept, the asteroid itself is used as the deflection "propellant". This study presents results of experiments designed to measure the thrust created by evaporation from a laser directed energy spot. We constructed a vacuum chamber to simulate space conditions, and installed a torsion balance that holds an "asteroid" sample. The sample is illuminated with a fiber array laser with flux levels up to 60 MW/m2 which allows us to simulate a mission level flux but on a small scale. We use a separate laser as well as a position sensitive centroid detector to readout the angular motion of the torsion balance and can thus determine the thrust. We compare the measured thrust to the models. Our theoretical models indicate a coupling coefficient well in excess of 100 μN/Woptical, though we assume a more conservative value of 80 μN/Woptical and then degrade this with an optical "encircled energy" efficiency of 0.75 to 60 μN/Woptical in our deflection modeling. Our measurements discussed here yield about 45 μN/Wabsorbed as a reasonable lower limit to the thrust per optical watt absorbed.

  11. Solvent Effects on the Photothermal Regeneration of CO2 in Monoethanolamine Nanofluids.

    PubMed

    Nguyen, Du; Stolaroff, Joshuah; Esser-Kahn, Aaron

    2015-11-25

    A potential approach to reduce energy costs associated with carbon capture is to use external and renewable energy sources. The photothermal release of CO2 from monoethanolamine mediated by nanoparticles is a unique solution to this problem. When combined with light-absorbing nanoparticles, vapor bubbles form inside the capture solution and release the CO2 without heating the bulk solvent. The mechanism by which CO2 is released remained unclear, and understanding this process would improve the efficiency of photothermal CO2 release. Here we report the use of different cosolvents to improve or reduce the photothermal regeneration of CO2 captured by monoethanolamine. We found that properties that reduce the residence time of the gas bubbles (viscosity, boiling point, and convection direction) can enhance the regeneration efficiencies. The reduction of bubble residence times minimizes the reabsorption of CO2 back into the capture solvent where bulk temperatures remain lower than the localized area surrounding the nanoparticle. These properties shed light on the mechanism of release and indicated methods for improving the efficiency of the process. We used this knowledge to develop an improved photothermal CO2 regeneration system in a continuously flowing setup. Using techniques to reduce residence time in the continuously flowing setup, such as alternative cosolvents and smaller fluid volumes, resulted in regeneration efficiency enhancements of over 200%. PMID:26523847

  12. Pulsed photothermal radiometry of human artery

    SciTech Connect

    Long, F.H.; Deutsch, T.F.

    1987-10-01

    Pulsed photothermal radiometry (PPTR) has been used to measure, in vitro, the optical attenuation coefficients of normal and diseased human artery at four wavelengths (308, 351, 488, 532 nm) in the near UV and visible spectrum. The advantages and limitations of this noncontact method of measuring the optical properties of biological material, as well as other potential applications, are discussed.

  13. Characterization of the bruise healing process using pulsed photothermal radiometry

    NASA Astrophysics Data System (ADS)

    Vidovič, Luka; Milanič, Matija; Randeberg, Lise L.; Majaron, Boris

    2013-06-01

    An analytical model of mass diffusion and biochemical transformation kinetics in bruise development and healing process was recently developed in order to simulate bruised skin color at various time points and enable objective determination of the time of injury. However, parameters of the model were not determined directly. Instead, biologically plausable values were applied in prior analyses. Pulsed photothermal radiometry (PPTR) allows noninvasive determination of the laser-induced temperature depth profile in human skin. We have applied this technique to characterize dynamics of extravasated hemoglobin concentration profile evolution. By applying Monte Carlo simulation of laser energy deposition and simulation of PPTR signal, a more exact comparison with measured temperature profiles is possible. We show that PPTR depth profiling can be used to derive rather accurate estimates of the hemoglobin mass diffusivity, hemoglobin degradation time, as well as approximate skin geometry. This enables assessment of the bruise healing dynamics and could offer a valuable addition to existing bruise age determination techniques.

  14. Photothermal microscopy applied to the characterization of nuclear fuel pellets

    NASA Astrophysics Data System (ADS)

    Zaldivar Escola, F.; Martínez, O. E.; Mingolo, N.; Kempf, R.

    2013-04-01

    The photothermal photodeflection technique is shown to provide information on the homogeneity of fuel pellets, pore distribution, clustering detection of pure urania and gadolinea and to provide a two-dimensional mapping of the thermal diffusivity correlated to the composition of the interdiffused Gadolinium and Uranium oxide. Histograms of the thermal diffusivity distribution become a reliable quantitative way of quantifying the degree of homogeneity and the width of the histogram can be used as a direct measure of the homogeneity. These quantitative measures of the homogeneity of the samples at microscopic levels provides a protocol that can be used as a reliable specification and quality control method for nuclear fuels, substituting with a single test a battery of expensive, time consuming and operator dependent techniques.

  15. Laser-induced photo-thermal magnetic imaging

    NASA Astrophysics Data System (ADS)

    Thayer, David A.; Lin, Yuting; Luk, Alex; Gulsen, Gultekin

    2012-08-01

    Due to the strong scattering nature of biological tissue, optical imaging beyond the diffusion limit suffers from low spatial resolution. In this letter, we present an imaging technique, laser-induced photo-thermal magnetic imaging (PMI), which uses laser illumination to induce temperature increase in a medium and magnetic resonance imaging to map the spatially varying temperature, which is proportional to absorbed energy. This technique can provide high-resolution images of optical absorption and can potentially be used for small animal as well as breast cancer and lymph node imaging. First, we describe the theory of PMI, including the modeling of light propagation and heat transfer in tissue. We also present experimental data with corresponding predictions from theoretical models, which show excellent agreement.

  16. Matter Wave Deflection through a Light Prism

    NASA Astrophysics Data System (ADS)

    Ronan, Joseph; Cronin, Alexander; Holmgren, William; Hromada, Ivan; Trubko, Raisa

    2011-10-01

    In optics, it is a well-known fact that a glass prism will bend a light beam incident on its surface. We present an atom optics experiment analogous to this phenomenon, but instead we use a light prism to deflect a beam of potassium atoms. We use a Mach-Zehnder atom interferometer to precisely measure atom beam deflections of as small as 5 nm. Through studying the beam deflection, we are able to investigate the dynamic polarizability and the magic zero wavelength of potassium.

  17. Observation by photothermal microscopy of increased silica absorption in laser damage induced by gold nanoparticles.

    SciTech Connect

    Bonneau, F.; Combis, P.; Rullier, J. L.; Commandre, M.; During, A.; Natoli, J. Y.; Pellin, M. J.; Savina, M. R.; Cottancin, E.; Pellarin, M.

    2003-11-10

    In order to understand laser-induced damage in glass, we subjected engineered SiO{sub 2} thin films containing sub-micron gold inclusions to high fluences, and observed the results using several means of analysis. We found decoupling in time between the emission of gold and that of silicon with samples containing gold spheres of diameter 3 nm. We have analyzed the changes in the silica optical absorption at 1064 nm, using photothermal deflection microscopy. We find, upon exceeding a sharp fluence threshold, a thousand-fold increase in absorption of the silica matrix around the inclusion. We conclude that ions from the inclusion permeate the surrounding silica, and form a highly absorbent mixture.

  18. Plasmonic nanoparticle-generated photothermal bubbles and their biomedical applications

    PubMed Central

    Lapotko, Dmitri

    2009-01-01

    This article is focused on the optical generation and detection of photothermal vapor bubbles around plasmonic nanoparticles. We report physical properties of such plasmonic nanobubbles and their biomedical applications as cellular probes. Our experimental studies of gold nanoparticle-generated photothermal bubbles demonstrated the selectivity of photothermal bubble generation, amplification of optical scattering and thermal insulation effect, all realized at the nanoscale. The generation and imaging of photothermal bubbles in living cells (leukemia and carcinoma culture and primary cancerous cells), and tissues (atherosclerotic plaque and solid tumor in animal) demonstrated a noninvasive highly sensitive imaging of target cells by small photothermal bubbles and a selective mechanical, nonthermal damage to the individual target cells by bigger photothermal bubbles due to a rapid disruption of cellular membranes. The analysis of the plasmonic nanobubbles suggests them as theranostic probes, which can be tuned and optically guided at cell level from diagnosis to delivery and therapy during one fast process. PMID:19839816

  19. Synergistic nanomedicine by combined gene and photothermal therapy.

    PubMed

    Kim, Jinhwan; Kim, Jihoon; Jeong, Cherlhyun; Kim, Won Jong

    2016-03-01

    To date, various nanomaterials with the ability for gene delivery or photothermal effect have been developed in the field of biomedicine. The therapeutic potential of these nanomaterials has raised considerable interests in their use in potential next-generation strategies for effective anticancer therapy. In particular, the advancement of novel nanomedicines utilizing both therapeutic strategies of gene delivery and photothermal effect has generated much optimism regarding the imminent development of effective and successful cancer treatments. In this review, we discuss current research progress with regard to combined gene and photothermal therapy. This review focuses on synergistic therapeutic systems combining gene regulation and photothermal ablation as well as logically designed nano-carriers aimed at enhancing the delivery efficiency of therapeutic genes using the photothermal effect. The examples detailed in this review provide insight to further our understanding of combinatorial gene and photothermal therapy, thus paving the way for the design of promising nanomedicines. PMID:26748259

  20. Development of optical diaphragm deflection sensors

    NASA Technical Reports Server (NTRS)

    Ghering, W. L.; Varshneya, D.; Jeffers, L. A.; Bailey, R. T.; Berthold, J. W.

    1985-01-01

    The objective of this project was to develop high-temperature pressure sensors using non-metallic components and optical sensing methods. The sensors are to operate over a temperature range from room temperature approx. 20C to 540C, to respond to internal pressure up to 690 kPa, to respond to external pressure up to 690 kPa, and to withstand external overpressure of 2070 kPa. Project tasks include evaluating sensing techniques and sensor systems. These efforts include materials and sensing method selection, sensor design, sensor fabrication, and sensor testing. Sensors are tested as a function of temperature, pressure, overpressure, and vibration. The project results show that high-temperature pressure sensors based on glass components and optical sensing methods are feasible. The microbend optical diaphragm deflection sensor exhibits the required sensitivity and stability for use as a pressure sensor with temperature compensation. for the microbend sensor, the 95% confidence level deviation of input pressure from the pressure calculated from the overall temperature-compensated calibration equation is 3.7% of full scale. The limitations of the sensors evaluated are primarily due to the restricted temperature range of suitable commercially available optical fibers and the problems associated with glass-to-metal pressure sealing over the entire testing temperature range.

  1. Noncontacting method for measuring angular deflection

    NASA Technical Reports Server (NTRS)

    Bryant, E. L. (Inventor)

    1980-01-01

    An apparatus is described for indicating the instantaneous angular deflection of an object about a selected axis without mechanical contact with the object. Light from a light source is transmitted through a flat refractor to a converging lens which focuses the light through another flat refractor onto a differential photocell. The first flat refractor is attached to the object such that when the object is deflected about the selected axis the refractor is also deflected about that axis. The two flat refractors are identical and they are placed an equal distance from the converging lens as are the light source and the photocell. The output of the photocell which is a function of image displacement is fed to a high gain amplifier that drives a galvanometer which rotates the second flat refractor. The second refractor is rotated so that the image displacement is very nearly zero making the galvanometer current a measure of the deflection of the object about the selected axis.

  2. Direct Measurement of Aerosol Absorption Using Photothermal Interferometry

    NASA Astrophysics Data System (ADS)

    Sedlacek, A. J.; Lee, J. A.

    2007-12-01

    Efforts to bound the contribution of light absorption in aerosol radiative forcing is still very much an active area of research in large part because aerosol extinction is dominated by light scattering. In response to this and other technical issues, the aerosol community has actively pursued the development of new instruments to measure aerosol absorption (e.g., photoacoustic spectroscopy (PAS) and multi-angle absorption photometer (MAAP)). In this poster, we introduce the technique of photothermal interferometry (PTI), which combines the direct measurement capabilities of photothermal spectroscopy (PTS) with high-sensitivity detection of the localized heating brought about by the PT process through interferometry. At its most fundamental level, the PTI technique measures the optical pathlength change that one arm of an interferometer (referred to as the 'probe' arm) experiences relative to the other arm of the interferometer (called the 'reference' arm). When the two arms are recombined at a beamsplitter, an interference pattern is created. If the optical pathlength in one arm of the interferometer changes, a commensurate shift in the interference pattern will take place. For the specific application of measuring light absorption, the heating of air surrounding the light- absorbing aerosol following laser illumination induces the optical pathlength change. This localized heating creates a refractive index gradient causing the probe arm of the interferometer to take a slightly different optical pathlength relative to the unperturbed reference arm. This effect is analogous to solar heating of a road causing mirages. As discussed above, this altered optical pathlength results in a shift in the interference pattern that is then detected as a change in the signal intensity by a single element detector. The current optical arrangement utilizes a folded Jamin interferometer design (Sedlacek, 2006) that provides a platform that is robust with respect to sensitivity

  3. Leaders and windshields: the art of deflecting essential information.

    PubMed

    Kerfoot, Karlene

    2004-01-01

    Do you know how much information you deflect in a day? Do you know what techniques you use to keep information at bay? We all erect windshields. It is just a matter of degree. Sometimes we deflect information in spite of our good intentions. If we are not present when people are in dialogue with us, we soon lose the attention of that person. If we are leading a meeting and the feedback begins to get uncomfortable for us, we can interject the techniques of the alpha male or alpha female, or a variety of our own. But the audience knows you are not listening, and they soon go underground with their comments and interpretations. Soon you are cut out of valuable feedback. Deflecting information by surrounding yourself with windshields just won't work. We need second and third opinions continually. One of Warren Bennis' (2002) ten traits to becoming a "tomorrow leader" is that of ensuring that the leader's boundaries are porous and permeable. In his view, leaders need the foresight to see around the corner long before others do. His belief is that the only way to do this is to be in touch with your customers, and the outside world. But that only happens when the leader's boundaries are porous and permeable so that information can seep in. Effective leaders learn to lead without windshields. PMID:15382398

  4. Leaders and windshields: the art of deflecting essential information.

    PubMed

    Kerfoot, Karlene

    2004-12-01

    Do you know how much information you deflect in a day? Do you know what techniques you use to keep information at bay? We all erect windshields. It is just a matter of degree. Sometimes we deflect information in spite of our good intentions. If we are not present when people are in dialogue with us, we soon lose the attention of that person. If we are leading a meeting and the feedback begins to get uncomfortable for us, we can interject the techniques of the alpha male or alpha female, or a variety of our own. But the audience knows you are not listening, and they soon go underground with their comments and interpretations. Soon you are cut out of valuable feedback. Deflecting information by surrounding yourself with windshields just won't work. We need second and third opinions continually. One of Warren Bennis' (2002) ten traits to becoming a "tomorrow leader" is that of ensuring that the leader's boundaries are porous and permeable. In his view, leaders need the foresight to see around the corner long before others do. His belief is that the only way to do this is to be in touch with your customers, and the outside world. But that only happens when the leader's boundaries are porous and permeable so that information can seep in. Effective leaders learn to lead without windshields. PMID:15690940

  5. Miniaturization of flight deflection measurement system

    NASA Technical Reports Server (NTRS)

    Fodale, Robert (Inventor); Hampton, Herbert R. (Inventor)

    1990-01-01

    A flight deflection measurement system is disclosed including a hybrid microchip of a receiver/decoder. The hybrid microchip decoder is mounted piggy back on the miniaturized receiver and forms an integral unit therewith. The flight deflection measurement system employing the miniaturized receiver/decoder can be used in a wind tunnel. In particular, the miniaturized receiver/decoder can be employed in a spin measurement system due to its small size and can retain already established control surface actuation functions.

  6. Shielded serpentine traveling wave tube deflection structure

    DOEpatents

    Hudson, C.L.; Spector, J.

    1994-12-27

    A shielded serpentine slow wave deflection structure is disclosed having a serpentine signal conductor within a channel groove. The channel groove is formed by a serpentine channel in a trough plate and a ground plane. The serpentine signal conductor is supported at its ends by coaxial feed through connectors. A beam interaction trough intersects the channel groove to form a plurality of beam interaction regions wherein an electron beam may be deflected relative to the serpentine signal conductor. 4 figures.

  7. Cu7.2S4 nanocrystals: a novel photothermal agent with a 56.7% photothermal conversion efficiency for photothermal therapy of cancer cells.

    PubMed

    Li, Bo; Wang, Qian; Zou, Rujia; Liu, Xijian; Xu, Kaibing; Li, Wenyao; Hu, Junqing

    2014-03-21

    Copper sulphides, as a novel kind of photothermal agent for photothermal therapy (PTT) of cancer cells, have attracted increasing attention in recent years due to good photostability, synthetic simplicity, low toxicity and low cost. However, the unsatisfactory photothermal conversion efficiency of copper sulphides limits their bioapplication as PTT agents. Herein, Cu7.2S4 NCs with a mean size of ∼20 nm as a novel photothermal agent have been prepared by a simple thermal decomposition route. Moreover, these NCs exhibit strong near-infrared (NIR) absorption, good photostability and significant photothermal conversion efficiency up to 56.7% due to strong NIR absorption, good dispersity and suitable size. Importantly, these NCs can be very compatibly used as a 980 nm laser-driven PTT agent for the efficient PTT of cancer cells in vitro and in vivo. PMID:24509646

  8. The deflection of 2008 December 12 CME

    NASA Astrophysics Data System (ADS)

    Shen, C.; Wang, Y.; Liu, J.; Ye, P.; Wang, S.

    2010-12-01

    The deflection of CME, which would significant influence the CME's geoeffectiveness, is an important topic of space weather study. In this work, the deflection of 2008 December 12 CME during it propagated from the Sun to Earth will be detailed studied based on the combination of remote and in situ observations. First, the 3-dimensions parameters reconstructed by Graduated Cylindrical Shell (GCS) model based on the STEREO observations were used to study the propagation direction evolution of this CME during it propagated in near solar space. During this phase, this CME deflect from high latitude region to equator in meridian plane but propagated almost along the longitude of W7 in ecliptic plane. Further, whether this CME deflected during it propagated in interplanetary space has also been checked. Based on the remote observations, if this CME propagated radially during it propagated in interplanetary space, it may arrived the Earth and then hit the STEREO A rather than hit STEREO B. But, the in situ observations show contrary results that this CME arrived the Earth and hit the STEREO B but missed STEREO A. This result show direct evidence that this CME deflected to east in ecliptic plane during it propagated in interplanetary space. The kinematic deflection model developed by Wang et. al (2004) has been applied on this CME. The calculation results of this model correspond well with the observational results.

  9. Emerging technology report: Development of a photothermal detoxification unit. Final report, October 1992-December 1994

    SciTech Connect

    Graham, J.L.; Dellinger, B.; Swartzbaugh, J.

    1995-08-01

    There has long been interest in utilizing photochemical methods for destroying hazardous organic materials. Researchers at the University of Dayton Research Institute (UDRI) have developed a unique photothermal process that overcomes many of the problems previously encountered with direct photochemical detoxification techniques. Specifically, it has been found that there are numerous advantages to conducting photochemical detoxification at relatively high temperatures. Under the conditions of simultaneous exposure to heat and ultraviolet (UV) radiation the rate of destructive photothermal reactions can be greatly increased and that these reactions result in the complete mineralization of the waste feed. Futhermore, it has been demonstrated that at the elevated temperatures used in this process the efficiency of UV radiation absorption also increases resulting in an overall improvement in process efficiency. These features (i.e., fast, efficient, and complete destruction of organic wastes) makes this process a promising technique for destroying hazardous organic wastes in the gas-phase.

  10. Ultrasharp nonlinear photothermal and photoacoustic resonances and holes beyond the spectral limit

    NASA Astrophysics Data System (ADS)

    Zharov, Vladimir P.

    2011-02-01

    High-resolution nonlinear laser spectroscopy based on absorption saturation, Lamb-dip and spectral hole-burning phenomena has contributed much to basic and applied photonics. Here, a laser spectroscopy based on nonlinear nanobubble-related photothermal and photoacoustic phenomena is presented. It shows ultrasharp resonances and dips up to a few nanometres wide in broad plasmonic spectra of nanoparticles. It also demonstrates narrowing of absorption spectra of dyes and cellular chromophores, as well as an increase in the sensitivity and resolution of the spectral hole-burning technique. This approach can permits the study of nonlinear plasmonics at a level of resolution beyond the spectral limits, the identification of weakly absorbing spectral holes, spectral optimization of photothermal nanotherapy, measurements of tiny red and blue resonance shifts in nanoplasmonic sensors, the use of negative contrast in photoacoustic technique, multispectral imaging and multicolour cytometry.

  11. Small deflection of a class of clamped thin plates using collocation

    NASA Technical Reports Server (NTRS)

    Worley, W. J.

    1977-01-01

    Equations are given for the optimization of a class of two-and three-dimensional structures. The application of existing analytical techniques to the response of thin clamped plates is described. The ratios of deflections to plate thickness are given for uniform transverse loads as well as for uniform plus linearly varying transverse loads. Deflections are presented at angular increments of 5 degrees and at radial increments of 0.1 of the radius.

  12. Infrared photothermal spectroscopy in the science of human nutrition

    NASA Astrophysics Data System (ADS)

    Bicanic, D.; Fink, T.; Franko, M.; Močnik, G.; v/d Bovenkamp, P.; van Veldhuizen, B.; Gerkema, E.

    1999-03-01

    Various (hyphenated) photothermal detection schemes are proposed and used for spectroscopic quantitation of trans fatty acids in margarines and edible oils. Other potential applications are also discussed.

  13. Deflection-Based Aircraft Structural Loads Estimation with Comparison to Flight

    NASA Technical Reports Server (NTRS)

    Lizotte, Andrew M.; Lokos, William A.

    2005-01-01

    Traditional techniques in structural load measurement entail the correlation of a known load with strain-gage output from the individual components of a structure or machine. The use of strain gages has proved successful and is considered the standard approach for load measurement. However, remotely measuring aerodynamic loads using deflection measurement systems to determine aeroelastic deformation as a substitute to strain gages may yield lower testing costs while improving aircraft performance through reduced instrumentation weight. With a reliable strain and structural deformation measurement system this technique was examined. The objective of this study was to explore the utility of a deflection-based load estimation, using the active aeroelastic wing F/A-18 aircraft. Calibration data from ground tests performed on the aircraft were used to derive left wing-root and wing-fold bending-moment and torque load equations based on strain gages, however, for this study, point deflections were used to derive deflection-based load equations. Comparisons between the strain-gage and deflection-based methods are presented. Flight data from the phase-1 active aeroelastic wing flight program were used to validate the deflection-based load estimation method. Flight validation revealed a strong bending-moment correlation and slightly weaker torque correlation. Development of current techniques, and future studies are discussed.

  14. Deflection-Based Structural Loads Estimation From the Active Aeroelastic Wing F/A-18 Aircraft

    NASA Technical Reports Server (NTRS)

    Lizotte, Andrew M.; Lokos, William A.

    2005-01-01

    Traditional techniques in structural load measurement entail the correlation of a known load with strain-gage output from the individual components of a structure or machine. The use of strain gages has proved successful and is considered the standard approach for load measurement. However, remotely measuring aerodynamic loads using deflection measurement systems to determine aeroelastic deformation as a substitute to strain gages may yield lower testing costs while improving aircraft performance through reduced instrumentation weight. This technique was examined using a reliable strain and structural deformation measurement system. The objective of this study was to explore the utility of a deflection-based load estimation, using the active aeroelastic wing F/A-18 aircraft. Calibration data from ground tests performed on the aircraft were used to derive left wing-root and wing-fold bending-moment and torque load equations based on strain gages, however, for this study, point deflections were used to derive deflection-based load equations. Comparisons between the strain-gage and deflection-based methods are presented. Flight data from the phase-1 active aeroelastic wing flight program were used to validate the deflection-based load estimation method. Flight validation revealed a strong bending-moment correlation and slightly weaker torque correlation. Development of current techniques, and future studies are discussed.

  15. Photothermal Characterization of Thermochromic Materials for Tunable Thermal Devices

    NASA Astrophysics Data System (ADS)

    Li Voti, R.; Leahu, G. L.; Larciprete, M. C.; Sibilia, C.; Bertolotti, M.

    2015-06-01

    A detailed infrared study of the semiconductor-to-metal transition (SMT) in a vanadium dioxide film deposited on a silicon wafer is presented. The phase transition is studied in the mid-infrared (MIR) region by analyzing the transmittance and the reflectance measurements, and the calculated emissivity. The temperature behavior of the emissivity during the SMT puts into evidence the phenomenon of the anomalous absorption in which has been explained by applying the Maxwell-Garnett effective medium approximation theory, together with a strong hysteresis phenomenon, both useful to design tunable thermal devices. Photothermal radiometry has been applied in order to study the changes in the modulated emissivity induced by a laser. Experimental results show how the use of these techniques represent a good tool for a quantitative measurement of the optothermal properties of vanadium dioxide-based structures.

  16. Modulated photothermal radiometry applied to semitransparent samples: Models and experiments

    NASA Astrophysics Data System (ADS)

    André, S.; Rémy, B.; Maillet, D.; Degiovanni, A.; Serra, J.-J.

    2004-09-01

    Mathematical modeling is presented of the combined conductive and radiative heat transfer occurring in a semitransparent material (STM) subjected to a periodic heat flux. The models rely on the quadrupole method, which is a very powerful tool to obtain analytical solutions in the Fourier or Laplace domain. Photoacoustic or photothermal radiometry techniques are reviewed. Two groups of methods are discussed depending on whether the sample has natural or opaque interfaces to simulate radiative exchanges with the surroundings. The metrological problem of measuring the phonic thermal diffusivity of semitransparent materials is investigated. Theoretical simulations are given. They explain some typical features of the phase-lag signal of temperature responses. Experimental measurements on pure silica validate the results and prove that these methods are efficient for the thermal characterization of STM.

  17. Polyaniline-coated upconversion nanoparticles with upconverting luminescent and photothermal conversion properties for photothermal cancer therapy

    PubMed Central

    Xing, Yadong; Li, Luoyuan; Ai, Xicheng; Fu, Limin

    2016-01-01

    In this study, we developed a nanosystem based on upconversion nanoparticles (UCNPs) coated with a layer of polyaniline nanoparticles (PANPs). The UCNP induces upconversion luminescence for imaging and photothermal conversion properties are due to PANPs. In vitro experiments showed that the UCNPs-PANPs were nontoxic to cells even at a high concentration (800 µg mL−1). Blood analysis and histological experiments demonstrated that the UCNPs-PANPs exhibited no apparent toxicity in mice in vivo. Besides their efficacy in photothermal cancer cell ablation, the UCNP-PANP nanosystem was found to achieve an effective in vivo tumor ablation effect after irradiation using an 808 nm laser. These results demonstrate the potential of the hybrid nanocomposites for use in imaging-guided photothermal therapy. PMID:27621625

  18. Gold nanorods as photothermal agents and autofluorescence enhancer to track cell death during plasmonic photothermal therapy

    NASA Astrophysics Data System (ADS)

    Kannadorai, Ravi Kumar; Chiew, Geraldine Giap Ying; Luo, Kathy Qian; Liu, Quan

    2015-07-01

    The transverse and longitudinal plasmon resonance in gold nanorods can be exploited to localize the photothermal therapy and influence the fluorescence to monitor the treatment outcome at the same time. While the longitudinal plasmon peak contributes to the photothermal effect, the transverse peak can enhance fluorescence. After cells take in PEGylated nanorods through endocytosis, autofluorescence from endogenous fluorophores such as nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) in the mitochondria is enhanced two times, which is a good indicator of the respiratory status of the cell. When cells are illuminated continuously with near infrared laser, the temperature reaches the hyperthermic region within the first four minutes, which demonstrates the efficiency of gold nanorods in photothermal therapy. The cell viability test and autofluorescence intensity show good correlation indicating the progress of cell death over time.

  19. Polyaniline-coated upconversion nanoparticles with upconverting luminescent and photothermal conversion properties for photothermal cancer therapy.

    PubMed

    Xing, Yadong; Li, Luoyuan; Ai, Xicheng; Fu, Limin

    2016-01-01

    In this study, we developed a nanosystem based on upconversion nanoparticles (UCNPs) coated with a layer of polyaniline nanoparticles (PANPs). The UCNP induces upconversion luminescence for imaging and photothermal conversion properties are due to PANPs. In vitro experiments showed that the UCNPs-PANPs were nontoxic to cells even at a high concentration (800 µg mL(-1)). Blood analysis and histological experiments demonstrated that the UCNPs-PANPs exhibited no apparent toxicity in mice in vivo. Besides their efficacy in photothermal cancer cell ablation, the UCNP-PANP nanosystem was found to achieve an effective in vivo tumor ablation effect after irradiation using an 808 nm laser. These results demonstrate the potential of the hybrid nanocomposites for use in imaging-guided photothermal therapy. PMID:27621625

  20. Temperature Distributions in Piezoelectric Photothermal Spectroscopy

    NASA Astrophysics Data System (ADS)

    Zakrzewski, J.; Maliński, M.; Strzałkowski, K.

    2013-04-01

    Piezoelectric photothermal spectroscopy is a method in which the stress and strain of a sample due to the absorption of electromagnetic radiation is detected by a piezoelectric transducer. The temperature distribution in the sample is the basis to obtain the theoretical amplitude and phase of photothermal piezoelectric spectra. In contrast to microphone detection, which needs only the temperature at one of the sample surfaces, in the piezoelectric one, it is necessary to know the spatial temperature distribution. The distributions given by Blonskij and by the modified interferential model of Malinski are applied. The influence of defect states in a volume and at the surfaces on the character of the amplitude and phase piezoelectric spectra is analyzed. The comparison of these approximate models and the two-layer one of Fernelius is presented.

  1. Microscopic thermoelastic characterizations by interferometric photothermal microscopy

    NASA Astrophysics Data System (ADS)

    Jumel, Julien; Lepoutre, François; Rochais, Denis; Enguehard, Franck

    2003-01-01

    Some publications have demonstrated that local thermoelastic behavior in materials can be revealed using a photothermal microscope coupled with an interferometer, but up to now the quantitative data that can be extracted from these measures are not established clearly. We present analysis of the signals, numerical simulations, and experimental results which demonstrate that the thermal diffusivity, the elastic anisotropy, and the principal directions of anisotropy orientation can be obtained with a microscopic resolution.

  2. Accelerated Testing Of Photothermal Degradation Of Polymers

    NASA Technical Reports Server (NTRS)

    Kim, Soon Sam; Liang, Ranty Hing; Tsay, Fun-Dow

    1989-01-01

    Electron-spin-resonance (ESR) spectroscopy and Arrhenius plots used to determine maximum safe temperature for accelerated testing of photothermal degradation of polymers. Aging accelerated by increasing illumination, temperature, or both. Results of aging tests at temperatures higher than those encountered in normal use valid as long as mechanism of degradation same throughout range of temperatures. Transition between different mechanisms at some temperature identified via transition between activation energies, manifesting itself as change in slope of Arrhenius plot at that temperature.

  3. Mission analysis for the ion beam deflection of fictitious asteroid 2015 PDC

    NASA Astrophysics Data System (ADS)

    Bombardelli, Claudio; Amato, Davide; Cano, Juan Luis

    2016-01-01

    Based on a hypothetical asteroid impact scenario proposed during the 2015 IAA Planetary Defense Conference (PDC), we study the deflection of fictitious asteroid 2015 PDC starting from ephemeris data provided by the conference organizers. A realistic mission scenario is investigated that makes use of an ion beam shepherd spacecraft as a primary deflection technique. The article deals with the design of a low-thrust rendezvous trajectory to the asteroid, the estimation of the propagated covariance ellipsoid and the outcome of an ion beam slow-push deflection starting from three worst case scenarios (impacts in New Delhi, Dhaka and Tehran). Displacing the impact point towards an extremely low-populated, easy-to-evacuate region, as opposed to full deflection, is found to be a more effective mitigation approach. Mission design, technical and political aspects are discussed.

  4. Deflection unit for multi-beam mask making

    NASA Astrophysics Data System (ADS)

    Letzkus, Florian; Butschke, Joerg; Irmscher, Mathias; Jurisch, Michael; Klingler, Wolfram; Platzgummer, Elmar; Klein, Christof; Loeschner, Hans; Springer, Reinhard

    2008-10-01

    Two main challenges of future mask making are the decreasing throughput of the pattern generators and the insufficient line edge roughness of the resist structures. The increasing design complexity with smaller feature sizes combined with additional pattern elements of the Optical Proximity Correction generates huge data volumes which reduce correspondingly the throughput of conventional single e-beam pattern generators. On the other hand the achievable line edge roughness when using sensitive chemically amplified resists does not fulfill the future requirements. The application of less sensitive resists may provide an improved roughness, however on account of throughput, as well. To overcome this challenge a proton multi-beam pattern generator is developed [1]. Starting with a highly parallel broad beam, an aperture-plate is used to generate thousands of separate spot beams. These beams pass through a blanking-plate unit, based on a CMOS device for de-multiplexing the writing data and equipped with electrodes placed around the apertures switching the beams "on" or "off", dependent on the desired pattern. The beam array is demagnified by a 200x reduction optics and the exposure of the entire substrate is done by a continuous moving stage. One major challenge is the fabrication of the required high aspect deflection electrodes and their connection to the CMOS device. One approach is to combine a post-processed CMOS chip with a MEMS component containing the deflection electrodes and to realize the electrical connection of both by vertical integration techniques. For the evaluation and assessment of this considered scheme and fabrication technique, a proof-of-concept deflection unit has been realized and tested. Our design is based on the generation of the deflection electrodes in a silicon membrane by etching trenches and oxide filling afterwards. In a 5mm x 5mm area 43,000 apertures with the corresponding electrodes have been structured and wired individually or in

  5. PHOTOTHERMAL DESTRUCTION OF THE VAPOR OF ORGANIC COMPOUNDS

    EPA Science Inventory

    The results of thermal and photothermal destruction of the vapors of organic compounds were compared by conducting tests in a photothermal detoxification unit. enon are lamp was used as the irradiation source. he tests were conducted on trichlorethylene (TCE), 1,2-dichlorobenzene...

  6. Determination of doping effects on Si and GaAs bulk samples properties by photothermal investigations

    NASA Astrophysics Data System (ADS)

    Abroug, Sameh; Saadallah, Faycel; Yacoubi, Noureddine

    2007-11-01

    The knowledge of doping effects on optical and thermal properties of semiconductors is crucial for the development of opto-electronic compounds. The purpose of this work is to investigate these effects by mirage effect technique and spectroscopic ellipsometry SE. The near gap optical spectra are obtained from photothermal signal for differently doped Si and GaAs bulk samples. However, the above bandgap absorption is determined from SE. These spectra show that absorption in the near IR increases with dopant density and also the bandgap shifts toward low energies. This behavior is due to free carrier absorption which could be obtained by subtracting phonon-assisted absorption from the measured spectrum. This carrier absorption is related to the dopant density through a semi-empirical model. We have also used the photothermal signal phase to measure the influence of doping on thermal diffusivity.

  7. Photothermal and infrared thermography characterizations of thermal diffusion in hydroxyapatite materials

    NASA Astrophysics Data System (ADS)

    Bante-Guerra, J.; Conde-Contreras, M.; Trujillo, S.; Martinez-Torres, P.; Cruz-Jimenez, B.; Quintana, P.; Alvarado-Gil, J. J.

    2009-02-01

    Non destructive analysis of hydroxyapatite materials is an active research area mainly in the study of dental pieces and bones due to the importance these pieces have in medicine, archeology, dentistry, forensics and anthropology. Infrared thermography and photothermal techniques constitute highly valuable tools in those cases. In this work the quantitative analysis of thermal diffusion in bones is presented. The results obtained using thermographic images are compared with the ones obtained from the photothermal radiometry. Special emphasis is done in the analysis of samples with previous thermal damage. Our results show that the treatments induce changes in the physical properties of the samples. These results could be useful in the identification of the agents that induced modifications of unknown origin in hydroxyapatite structures.

  8. Ultrasharp nonlinear photothermal and photoacoustic resonances and holes beyond the spectral limit

    PubMed Central

    Zharov, Vladimir P.

    2012-01-01

    High-resolution nonlinear laser spectroscopy based on absorption saturation, Lamb-dip and spectral hole-burning phenomena have contributed much to basic and applied photonics. Here, a laser spectroscopy based on nonlinear photothermal and photoacoustic phenomena is presented. It shows ultrasharp resonances and dips up to a few nanometres wide in broad plasmonic spectra of nanoparticles. It also demonstrates narrowing of absorption spectra of dyes and chromophores, as well as an increase in the sensitivity and resolution of the spectral hole-burning technique. This approach can permit the study of laser-nanoparticle interactions at a level of resolution beyond the spectral limits, identification of weakly absorbing spectral holes, spectral optimization of photothermal nanotherapy, measurements of tiny red and blue plasmon resonance shifts, multispectral imaging and multicolour cytometry. PMID:25558274

  9. Photothermal cancer therapy via femtosecond-laser-excited FePt nanoparticles.

    PubMed

    Chen, Cheng-Lung; Kuo, Ling-Ru; Lee, Shin-Yu; Hwu, Yeu-Kuang; Chou, Shang-Wei; Chen, Chia-Chun; Chang, Fu-Hsiung; Lin, Kung-Hsuan; Tsai, Dzung-Han; Chen, Yang-Yuan

    2013-01-01

    FePt nanoparticles (NPs) have recently been revealed to be significant multifunctional materials for the applications of biomedical imaging, drug delivery and magnetic hyperthermia due to their novel magnetic properties. In this study, a newly discovered photothermal effect activated by the near infrared (NIR) femtosecond laser for FePt NPs was demonstrated. The threshold laser energy to destroy cancer cells was found to be comparable to that of gold nanorods (Au NRs) previously reported. Through the thermal lens technique, it was concluded that the temperature of the FePt NPs can be heated up to a couple of hundreds degree C in picoseconds under laser irradiation due to the excellent photothermal transduction efficiency of FePt NPs. This finding boosts FePt NPs versatility in multifunctional targeted cancer therapy. PMID:23137396

  10. Photothermal tomography for the functional and structural evaluation, and early mineral loss monitoring in bones

    PubMed Central

    Kaiplavil, Sreekumar; Mandelis, Andreas; Wang, Xueding; Feng, Ting

    2014-01-01

    Salient features of a new non-ionizing bone diagnostics technique, truncated-correlation photothermal coherence tomography (TC-PCT), exhibiting optical-grade contrast and capable of resolving the trabecular network in three dimensions through the cortical region with and without a soft-tissue overlayer are presented. The absolute nature and early demineralization-detection capability of a marker called thermal wave occupation index, estimated using the proposed modality, have been established. Selective imaging of regions of a specific mineral density range has been demonstrated in a mouse femur. The method is maximum-permissible-exposure compatible. In a matrix of bone and soft-tissue a depth range of ~3.8 mm has been achieved, which can be increased through instrumental and modulation waveform optimization. Furthermore, photoacoustic microscopy, a comparable modality with TC-PCT, has been used to resolve the trabecular structure and for comparison with the photothermal tomography. PMID:25136480

  11. Photothermal tomography for the functional and structural evaluation, and early mineral loss monitoring in bones.

    PubMed

    Kaiplavil, Sreekumar; Mandelis, Andreas; Wang, Xueding; Feng, Ting

    2014-08-01

    Salient features of a new non-ionizing bone diagnostics technique, truncated-correlation photothermal coherence tomography (TC-PCT), exhibiting optical-grade contrast and capable of resolving the trabecular network in three dimensions through the cortical region with and without a soft-tissue overlayer are presented. The absolute nature and early demineralization-detection capability of a marker called thermal wave occupation index, estimated using the proposed modality, have been established. Selective imaging of regions of a specific mineral density range has been demonstrated in a mouse femur. The method is maximum-permissible-exposure compatible. In a matrix of bone and soft-tissue a depth range of ~3.8 mm has been achieved, which can be increased through instrumental and modulation waveform optimization. Furthermore, photoacoustic microscopy, a comparable modality with TC-PCT, has been used to resolve the trabecular structure and for comparison with the photothermal tomography. PMID:25136480

  12. Brachytherapy needle deflection evaluation and correction

    SciTech Connect

    Wan Gang; Wei Zhouping; Gardi, Lori; Downey, Donal B.; Fenster, Aaron

    2005-04-01

    In prostate brachytherapy, an 18-gauge needle is used to implant radioactive seeds. This thin needle can be deflected from the preplanned trajectory in the prostate, potentially resulting in a suboptimum dose pattern and at times requiring repeated needle insertion to achieve optimal dosimetry. In this paper, we report on the evaluation of brachytherapy needle deflection and bending in test phantoms and two approaches to overcome the problem. First we tested the relationship between needle deflection and insertion depth as well as whether needle bending occurred. Targeting accuracy was tested by inserting a brachytherapy needle to target 16 points in chicken tissue phantoms. By implanting dummy seeds into chicken tissue phantoms under 3D ultrasound guidance, the overall accuracy of seed implantation was determined. We evaluated methods to overcome brachytherapy needle deflection with three different insertion methods: constant orientation, constant rotation, and orientation reversal at half of the insertion depth. Our results showed that needle deflection is linear with needle insertion depth, and that no noticeable bending occurs with needle insertion into the tissue and agar phantoms. A 3D principal component analysis was performed to obtain the population distribution of needle tip and seed position relative to the target positions. Our results showed that with the constant orientation insertion method, the mean needle targeting error was 2.8 mm and the mean seed implantation error was 2.9 mm. Using the constant rotation and orientation reversal at half insertion depth methods, the deflection error was reduced. The mean needle targeting errors were 0.8 and 1.2 mm for the constant rotation and orientation reversal methods, respectively, and the seed implantation errors were 0.9 and 1.5 mm for constant rotation insertion and orientation reversal methods, respectively.

  13. Advanced Gold Nanomaterials for Photothermal Therapy of Cancer.

    PubMed

    Ahmad, Rasheed; Fu, Juan; He, Nongyue; Li, Song

    2016-01-01

    Photothermal therapy represents a non-invasive therapeutic tool to eradicate cancer tumor with minimum toxic effects. In this ablative therapy, accurate delivery of efficient photothermal conversion agents followed by laser irradiation results in tumor ablation with lower toxicity compared to other cancer therapies. Gold nanomaterials are efficient to passively target and deliver photothermal agents to the cancer tumor. Through surface plasma resonance, gold nanomaterials including nanorods, nanostars, nanoflowers, nanocages and nanoshells exhibited strong NIR absorption and are widely utilized during photothermal ablative therapy of cancer. Currently, researchers have devoted their attention to minimize toxicity of photothermal agents using modified probe design. By developing this noninvasive cancer therapy, expectations to minimize toxicity of cancer treatment may become reality sooner. PMID:27398434

  14. Selective nanoparticle-directed photothermal ablation of the canine prostate

    NASA Astrophysics Data System (ADS)

    Schwartz, Jon A.; Price, Roger E.; Gill-Sharp, Kelly L.; Sang, Krystina L.; Khorchani, Jennifer D.; Payne, J. Donald; Goodwin, Bradford S.

    2011-03-01

    This study adapted AuroLase® Therapy, previously reported for the treatment of brain tumors, to the treatment of prostate disease by 1) using normal canine prostate in vivo, directly injected with a solution of nanoparticles as a proxy for prostate tumor and, 2) developing an appropriate laser dosimetry for prostate which is which is subablative in native prostate while simultaneously producing photothermal coagulation in prostate tissue containing therapeutic nanoshells. Healthy, mixed-breed hound dogs were given surgical laparotomies during which nanoshells were injected directly into one or both prostate hemispheres. Laser energy was delivered percutaneously to the parenchyma of the prostate along 1-5 longitudinal tracts via a liquid-cooled optical fiber catheter terminated with a 1-cm isotropic diffuser after which the incision was closed and sutured using standard surgical techniques. The photothermal lesions were permitted to resolve for up to 8 days, after which each animal was euthanized, necropsied, and the prostate taken for histopathological analysis. We developed a laser dosimetry which is sub- to marginally ablative in native prostate and simultaneously ablative of prostate tissue containing nanoshells which would indicate a viable means of treating tumors of the prostate which are known from other studies to accumulate nanoshells. Secondly, we determined that multiple laser treatments of nanoshell-containing prostate tissue could be accomplished while sparing the urethra and prostate capsule thermal damage. Finally, we determined that the extent of damage zone radii correlate positively with nanoshell concentration, and negatively to the length of time between nanoshell injection and laser treatment.

  15. Lateral-deflection-controlled friction force microscopy

    NASA Astrophysics Data System (ADS)

    Fukuzawa, Kenji; Hamaoka, Satoshi; Shikida, Mitsuhiro; Itoh, Shintaro; Zhang, Hedong

    2014-08-01

    Lateral-deflection-controlled dual-axis friction force microscopy (FFM) is presented. In this method, an electrostatic force generated with a probe-incorporated micro-actuator compensates for friction force in real time during probe scanning using feedback control. This equivalently large rigidity can eliminate apparent boundary width and lateral snap-in, which are caused by lateral probe deflection. The method can evolve FFM as a method for quantifying local frictional properties on the micro/nanometer-scale by overcoming essential problems to dual-axis FFM.

  16. Light deflection in gadolinium molybdate ferroelastic crystals

    NASA Astrophysics Data System (ADS)

    Staniorowski, Piotr; Bornarel, Jean

    2000-02-01

    The deflection of a He-Ne light beam by polydomain gadolinium molybdate (GMO) crystals has been studied with respect to incidence angle icons/Journals/Common/alpha" ALT="alpha" ALIGN="TOP"/> i on the sample at room temperature. The A and B deflected beams do not cross each other during the icons/Journals/Common/alpha" ALT="alpha" ALIGN="TOP"/> i variation, in contrast to results and calculations previously published. The model using the Fresnel equation confirms this result. The model presented is more accurate for numerical calculation than that using the Huygens construction.

  17. Deflection of large near-earth objects

    SciTech Connect

    Canavan, G.H.

    1999-01-11

    The Earth is periodically hit by near Earth objects (NEOs) ranging in size from dust to mountains. The small ones are a useful source of information, but those larger than about 1 km can cause global damage. The requirements for the deflection of NEOs with significant material strength are known reasonably well; however, the strength of large NEOs is not known, so those requirements may not apply. Meteor impacts on the Earth`s atmosphere give some information on strength as a function of object size and composition. This information is used here to show that large, weak objects could also be deflected efficiently, if addressed properly.

  18. Shielded serpentine traveling wave tube deflection structure

    DOEpatents

    Hudson, Charles L.; Spector, Jerome

    1994-01-01

    A shielded serpentine slow wave deflection structure (10) having a serpene signal conductor (12) within a channel groove (46). The channel groove (46) is formed by a serpentine channel (20) in a trough plate (18) and a ground plane (14). The serpentine signal conductor (12) is supported at its ends by coaxial feed through connectors 28. A beam interaction trough (22) intersects the channel groove (46) to form a plurality of beam interaction regions (56) wherein an electron beam (54) may be deflected relative to the serpentine signal conductor (12).

  19. Correct light deflection in Weyl conformal gravity

    NASA Astrophysics Data System (ADS)

    Cattani, Carlo; Scalia, Massimo; Laserra, Ettore; Bochicchio, Ivana; Nandi, Kamal K.

    2013-02-01

    The conformal gravity fit to observed galactic rotation curves requires γ>0. On the other hand, the conventional method for light deflection by galaxies gives a negative contribution to the Schwarzschild value for γ>0, which is contrary to observation. Thus, it is very important that the contribution to bending should in principle be positive, no matter how small its magnitude is. Here we show that the Rindler-Ishak method gives a positive contribution to Schwarzschild deflection for γ>0, as desired. We also obtain the exact local coupling term derived earlier by Sereno. These results indicate that conformal gravity can potentially test well against all astrophysical observations to date.

  20. Design of Spacecraft Missions to Test Kinetic Impact for Asteroid Deflection

    NASA Technical Reports Server (NTRS)

    Hernandez, Sonia; Barbee, Brent W.

    2011-01-01

    There are currently over 8,000 known near-Earth asteroids (NEAs), and more are being discovered on a continual basis. More than 1,200 of these are classified as Potentially Hazardous Asteroids (PHAs) because their Minimum Orbit Intersection Distance (MOID) with Earth's orbit is <= 0.05 AU and their estimated diameters are >= 150 m. To date, 178 Earth impact structures have been discovered, indicating that our planet has previously been struck with devastating force by NEAs and will be struck again. Such collisions are aperiodic events and can occur at any time. A variety of techniques have been proposed to defend our planet from NEA impacts by deflecting the incoming asteroid. However, none of these techniques have been tested. Unless rigorous testing is conducted to produce reliable asteroid deflection systems, we will be forced to deploy completely untested -- and therefore unreliable -- deflection missions when a sizable asteroid on a collision course with Earth is discovered. Such missions will have a high probability of failure. We propose to address this problem with a campaign of deflection technology test missions deployed to harmless NEAs. The objective of these missions is to safely evaluate and refine the mission concepts and asteroid deflection system designs. Our current research focuses on the kinetic impactor, one of the simplest proposed asteroid deflection techniques in which a spacecraft is sent to collide with an asteroid at high relative velocity. By deploying test missions in the near future, we can characterize the performance of this deflection technique and resolve any problems inherent to its execution before needing to rely upon it during a true emergency. In this paper we present the methodology and results of our survey, including lists of NEAs for which safe and effective kinetic impactor test missions may be conducted within the next decade. Full mission designs are also presented for the NEAs which offer the best mission opportunities.

  1. Efficiency improvement in the cantilever photothermal excitation method using a photothermal conversion layer.

    PubMed

    Inada, Natsumi; Asakawa, Hitoshi; Kobayashi, Taiki; Fukuma, Takeshi

    2016-01-01

    Photothermal excitation is a cantilever excitation method that enables stable and accurate operation for dynamic-mode AFM measurements. However, the low excitation efficiency of the method has often limited its application in practical studies. In this study, we propose a method for improving the photothermal excitation efficiency by coating cantilever backside surface near its fixed end with colloidal graphite as a photothermal conversion (PTC) layer. The excitation efficiency for a standard cantilever of PPP-NCHAuD with a spring constant of ≈40 N/m and a relatively stiff cantilever of AC55 with a spring constant of ≈140 N/m were improved by 6.1 times and 2.5 times, respectively, by coating with a PTC layer. We experimentally demonstrate high stability of the PTC layer in liquid by AFM imaging of a mica surface with atomic resolution in phosphate buffer saline solution for more than 2 h without any indication of possible contamination from the coating. The proposed method, using a PTC layer made of colloidal graphite, greatly enhances photothermal excitation efficiency even for a relatively stiff cantilever in liquid. PMID:27335733

  2. Efficiency improvement in the cantilever photothermal excitation method using a photothermal conversion layer

    PubMed Central

    Inada, Natsumi; Kobayashi, Taiki; Fukuma, Takeshi

    2016-01-01

    Summary Photothermal excitation is a cantilever excitation method that enables stable and accurate operation for dynamic-mode AFM measurements. However, the low excitation efficiency of the method has often limited its application in practical studies. In this study, we propose a method for improving the photothermal excitation efficiency by coating cantilever backside surface near its fixed end with colloidal graphite as a photothermal conversion (PTC) layer. The excitation efficiency for a standard cantilever of PPP-NCHAuD with a spring constant of ≈40 N/m and a relatively stiff cantilever of AC55 with a spring constant of ≈140 N/m were improved by 6.1 times and 2.5 times, respectively, by coating with a PTC layer. We experimentally demonstrate high stability of the PTC layer in liquid by AFM imaging of a mica surface with atomic resolution in phosphate buffer saline solution for more than 2 h without any indication of possible contamination from the coating. The proposed method, using a PTC layer made of colloidal graphite, greatly enhances photothermal excitation efficiency even for a relatively stiff cantilever in liquid. PMID:27335733

  3. Self-referenced prism deflection measurement schemes with microradian precision

    SciTech Connect

    Olson, Rebecca; Paul, Justin; Bergeson, Scott; Durfee, Dallin S

    2005-08-01

    We have demonstrated several inexpensive methods that can be used to measure the deflection angles of prisms with microradian precision. The methods are self-referenced, where various reversals are used to achieve absolute measurements without the need of a reference prism or any expensive precision components other than the prisms under test. These techniques are based on laser interferometry and have been used in our laboratory to characterize parallel-plate beam splitters, penta prisms, right-angle prisms, and corner cube reflectors using only components typically available in an optics laboratory.

  4. Frequency response of optical beam deflection by ultrasound in water.

    PubMed

    Caron, James N; DiComo, Greg P

    2014-11-10

    Acoustic waveforms create fluctuations in the index of refraction of the medium. An optical beam passing through the disturbance will be deflected or displaced from the original path. The acoustic wave can be detected by sending a laser through the disturbance and sensing the path changes of the beam with a position-sensitive photodetector. This paper presents a model of this interaction in water to predict the sensitivity and frequency response. The model demonstrates that the frequency response of the system is broadband, allowing detection from a few hundred hertz to 20 MHz. This technique has potential use for underwater acoustic sensing and ultrasonic inspection of materials. PMID:25402989

  5. Noncontacting measuring device to indicate deflection of turbopump internal rotating parts

    NASA Technical Reports Server (NTRS)

    Hamilton, D. B.; Grieser, D. R.; Plummer, A. M.; Ensminger, D.; Saccacio, E. J.; Kissel, J. W.

    1971-01-01

    Noncontacting, nondestructive techniques to measure vibrations and deflections of parts in future LOX and LH2 multistage turbopump prototypes are reported. The measurements include shaft vibration, vibration of turbine wheel and blades, blade clearance, vibration of impellers, value component flutter, and vibration of face seal components. Three techniques were selected for development: ultrasonic Doppler devices, flash X-ray, and light-pipe reflectance.

  6. Multiphoton and photothermal imaging of molecular events in cancer

    NASA Astrophysics Data System (ADS)

    Skala, Melissa

    2010-10-01

    Optical techniques are attractive for monitoring disease processes in living tissues because they are relatively cheap, non-invasive and provide a wealth of functional information. Multiphoton microscopy (MPM) and Optical Coherence Tomography (OCT) are two types of three-dimensional optical imaging modalities that have demonstrated great utility in pre-clinical models of disease. These techniques are particularly useful for identifying metabolic and molecular biomarkers in cancer. These biomarkers can be used to identify the mechanisms of tumor growth, and to predict the response of a particular tumor to treatment. Specifically, MPM of the co-enzymes NADH and FAD was used to quantify metabolic changes associated with developing cancers in vivo. This imaging technique exploits intrinsic sources of tissue contrast and thus does not require contrast agents. Ongoing work combines this metabolic imaging technique with vascular imaging to provide a comprehensive picture of oxygen supply and demand with tumor therapy. Molecular signaling represents a third critical component in tumor physiology. To this end we have recently developed photothermal OCT, which combines coherent detection with laser-heated gold nanoparticles to achieve high-resolution molecular contrast at deeper depths than MPM. This multi-functional imaging platform will provide unprecedented insight into oxygen supply and demand, and molecular signaling in response to tumor growth and targeted cancer therapies in pre-clinical models.

  7. Rural Youth and Anticipatory Goal Deflection.

    ERIC Educational Resources Information Center

    Curry, Evans W.; And Others

    Race, sex, community size, occupation of major wage earner, father's education, mother's education, and certainty of expectations were the variables used in this study to determine the "anticipatory occupational goal deflection" (AOGD) of urban and rural youth (blacks and whites) in Louisiana. Least squares analysis of variance and other…

  8. Laboratory experiments on arc deflection and instability

    SciTech Connect

    Zweben, S.; Karasik, M.

    2000-03-21

    This article describes experiments on arc deflection instability carried out during the past few years at the Princeton University Plasma Physics Laboratory (PPPL). The approach has been that of plasma physicists interested in arcs, but they believe these results may be useful to engineers who are responsible for controlling arc behavior in large electric steel furnaces.

  9. Simplified deflection-coil linearity testing

    NASA Technical Reports Server (NTRS)

    Kramer, G. P.

    1976-01-01

    Mask placed over face of image-dissecting photomultiplier tube has precision array of pinholes that permit light to impinge on tube at known points. Signals are fed to deflection coil which sweeps beam across each point without complex operator procedures.

  10. Measuring Deflections Of Propeller And Fan Blades

    NASA Technical Reports Server (NTRS)

    Kurkov, Anatole P.

    1993-01-01

    Method based on measurement of interruptions of laser beam provides information on deflections of blades of airplane propeller or unducted turbofan. Bends and twists deduced from timing of laser-beam shadows. Provides for nonintrusive measurement in wind tunnel or on open test stand.

  11. Particle beam and crabbing and deflecting structure

    DOEpatents

    Delayen, Jean

    2011-02-08

    A new type of structure for the deflection and crabbing of particle bunches in particle accelerators comprising a number of parallel transverse electromagnetic (TEM)-resonant) lines operating in opposite phase from each other. Such a structure is significantly more compact than conventional crabbing cavities operating the transverse magnetic TM mode, thus allowing low frequency designs.

  12. Improved laser ablation model for asteroid deflection

    NASA Astrophysics Data System (ADS)

    Vasile, Massimiliano; Gibbings, Alison; Watson, Ian; Hopkins, John-Mark

    2014-10-01

    This paper presents an improved laser ablation model and compares the performance - momentum coupling and deflection system mass - of laser ablation against contactless deflection methods based on ion-propulsion. The deflection of an asteroid through laser ablation is achieved by illuminating the surface of the asteroid with high intensity laser light. The absorbed energy induces the sublimation of the surface material and the generation of a plume of gas and ejecta. Similar to a rocket engine, the flow of expelled material produces a continuous and controllable thrust that could be used to modify the trajectory and tumbling motion of the asteroid. Recent results gained from a series of laser ablation experiments were used to improve the sublimation and deflection models. In each experiment a terrestrial olivine sample was ablated, under vacuum, with a 90 W continuous wave laser. The paper presents a model that better fits the outcomes of the experimental campaign, in particular in terms of mass flow rate and spot temperature.

  13. AIDA: The Asteroid Impact & Deflection Assessment Mission

    NASA Astrophysics Data System (ADS)

    Galvez, A.; Carnelli, I.; Michel, P.; Cheng, A. F.; Reed, C.; Ulamec, S.; Biele, J.; Abell, P.; Landis, R.

    2013-09-01

    The Asteroid Impact and Deflection Assessment (AIDA) mission, a joint effort of ESA, JHU/APL, NASA, OCA, and DLR, is the first demonstration of asteroid deflection and assessment via kinetic impact. AIDA consists of two independent but mutually supporting mission elements, one of which is the asteroid kinetic impactor and the other is the characterization spacecraft. These two missions are, respectively, JHU/APL's Double Asteroid Redirection Test (DART) and the European Space Agency's Asteroid Investigation Mission (AIM) missions. As in the separate DART and AIM studies, the target of this mission is the binary asteroid [65803] Didymos in October, 2022. For a successful joint mission, one spacecraft, DART, would impact the secondary of the Didymos system while AIM would observe and measure any change in the relative orbit. AIM will be the first probe to characterise a binary asteroid, especially from the dynamical point of view, but also considering its interior and subsurface composition. The mission concept focuses on the monitoring aspects i.e., the capability to determine in-situ the key physical properties of a binary asteroid playing a role in the system's dynamic behavior. DART will be the first ever space mission to deflect the trajectory of an asteroid in a measurable way.- It is expected that the deflection can be measured as a change in the relative orbit period with a precision better than 10%. The joint AIDA mission will return vital data to determine the momentum transfer efficiency of the kinetic impact [1,2].

  14. High-resolution and high-stability electromagnetic-deflection control system for EB lithography system

    NASA Astrophysics Data System (ADS)

    Nagata, Koji; Okumura, Masahide; Maio, Kenji; Fujii, Akira; Andoh, Hisashi; Morimura, Toshiyuki; Hayakawa, Hajime

    2001-08-01

    A stable high-resolution electromagnetic deflection control circuit for an electron-beam lithography (EBL) system has been developed. This deflection control circuit has enabled an EBL system to deal with a wide deflection area of 2.5-mm square having fine address units for a pattern placement of 1.25 nm. The deflection-control circuit consists of a new digital to analog converter (DAC) circuit, whose resolution is 21 bits, and a low-drift current-amplifier circuit. To achieve such high-stability and high-resolution, we had to develop a low noise-current cell structure for the new DAC circuit, because the output-signal noise of the DAC circuit is a major source of interference at the desired resolution. A local temperature control technique has been incorporated into the circuit to reduce fluctuations of the deflection control signal caused by ambient thermal variations. The low noise-current cell structure, which consists of multiple current buffers and low-pass filters, is placed between a constant current source circuit and a differential-switch circuit for each bit of the DAC circuit. The simulation results of the DAC circuit showed that the output-signal noise of the DAC circuit could be reduced to less than 0.4 nm rms, which is small enough to achieve the desired resolution. As the results of the experimentally evaluation of the deflection control circuit show, the total noise of the deflection-control signal obtained was less than 0.6 nm rms and the signal stability obtained was better than 0.3 nm rms. An evaluation of the performance of the new EBL system to which the new deflection control circuit was applied, showed that the critical-dimension accuracy obtained was better than 5 nm (3sigma) and the positioning accuracy obtained was better than 10 nm (3sigma) for the area controlled by electromagnetic deflector.

  15. Asteroid Impact & Deflection Assessment mission: Kinetic impactor

    NASA Astrophysics Data System (ADS)

    Cheng, A. F.; Michel, P.; Jutzi, M.; Rivkin, A. S.; Stickle, A.; Barnouin, O.; Ernst, C.; Atchison, J.; Pravec, P.; Richardson, D. C.

    2016-02-01

    The Asteroid Impact & Deflection Assessment (AIDA) mission will be the first space experiment to demonstrate asteroid impact hazard mitigation by using a kinetic impactor to deflect an asteroid. AIDA is an international cooperation, consisting of two mission elements: the NASA Double Asteroid Redirection Test (DART) mission and the ESA Asteroid Impact Mission (AIM) rendezvous mission. The primary goals of AIDA are (i) to test our ability to perform a spacecraft impact on a potentially hazardous near-Earth asteroid and (ii) to measure and characterize the deflection caused by the impact. The AIDA target will be the binary near-Earth asteroid (65803) Didymos, with the deflection experiment to occur in late September, 2022. The DART impact on the secondary member of the binary at ~7 km/s is expected to alter the binary orbit period by about 4 minutes, assuming a simple transfer of momentum to the target, and this period change will be measured by Earth-based observatories. The AIM spacecraft will characterize the asteroid target and monitor results of the impact in situ at Didymos. The DART mission is a full-scale kinetic impact to deflect a 150 m diameter asteroid, with known impactor conditions and with target physical properties characterized by the AIM mission. Predictions for the momentum transfer efficiency of kinetic impacts are given for several possible target types of different porosities, using Housen and Holsapple (2011) crater scaling model for impact ejecta mass and velocity distributions. Results are compared to numerical simulation results using the Smoothed Particle Hydrodynamics code of Jutzi and Michel (2014) with good agreement. The model also predicts that the ejecta from the DART impact may make Didymos into an active asteroid, forming an ejecta coma that may be observable from Earth-based telescopes. The measurements from AIDA of the momentum transfer from the DART impact, the crater size and morphology, and the evolution of an ejecta coma will

  16. Deflection of uncooperative targets using laser ablation

    NASA Astrophysics Data System (ADS)

    Thiry, Nicolas; Vasile, Massimiliano

    2015-09-01

    Owing to their ability to move a target in space without requiring propellant, laser-based deflection methods have gained attention among the research community in the recent years. With laser ablation, the vaporized material is used to push the target itself allowing for a significant reduction in the mass requirement for a space mission. Specifically, this paper addresses two important issues which are thought to limit seriously the potential efficiency of a laser-deflection method: the impact of the tumbling motion of the target as well as the impact of the finite thickness of the material ablated in the case of a space debris. In this paper, we developed a steady-state analytical model based on energetic considerations in order to predict the efficiency range theoretically allowed by a laser deflection system in absence of the two aforementioned issues. A numerical model was then implemented to solve the transient heat equation in presence of vaporization and melting and account for the tumbling rate of the target. This model was also translated to the case where the target is a space debris by considering material properties of an aluminium 6061-T6 alloy and adapting at every time-step the size of the computational domain along with the recession speed of the interface in order to account for the finite thickness of the debris component. The comparison between the numerical results and the analytical predictions allow us to draw interesting conclusions regarding the momentum coupling achievable by a given laser deflection system both for asteroids and space debris in function of the flux, the rotation rate of the target and its material properties. In the last section of this paper, we show how a reasonably small spacecraft could deflect a 56m asteroid with a laser system requiring less than 5kW of input power.

  17. Asteroid Deflection: How, Where and When?

    NASA Astrophysics Data System (ADS)

    Fargion, D.

    2008-10-01

    To deflect impact-trajectory of massive and spinning km^3 asteroid by a few terrestrial radiuses one need a large momentum exchange. The dragging of huge spinning bodies in space by external engine seems difficult or impossible. Our solution is based on the landing of multi screw-rockets, powered by mini-nuclear engines, on the body, that dig a small fraction of the soil surface to use as an exhaust propeller, ejecting it vertically in phase among themselves. Such a mass ejection increases the momentum exchange, their number redundancy guarantees the stability of the system. The slow landing (below ≃ 40 cm s^{-1}) of each engine-unity at those very low gravity field, may be achieved by safe rolling and bouncing along the surface. The engine array tuned activity, overcomes the asteroid angular velocity. Coherent turning of the jet heads increases the deflection efficiency. A procession along its surface may compensate at best the asteroid spin. A small skin-mass (about 2×10^4 tons) may be ejected by mini-nuclear engines. Such prototypes may also build first safe galleries for humans on the Moon. Conclusive deflecting tests might be performed on remote asteroids. The incoming asteroid 99942 Apophis (just 2% of km^3) may be deflected safely a few Earth radiuses. Its encounter maybe not just a hazard but an opportunity, learning how to land, to dig, to build and also to nest safe human station inside. Asteroids amplified deflections by gravity swing may be driven into longest planetary journeys, beginning i.e. with the preliminary landing of future missions on Mars' moon-asteroid Phobos or Deimos.

  18. Fast wide-field photothermal and quantitative phase cell imaging with optical lock-in detection

    PubMed Central

    Eldridge, Will J.; Meiri, Amihai; Sheinfeld, Adi; Rinehart, Matthew T.; Wax, Adam

    2014-01-01

    We present a fast, wide-field holography system for detecting photothermally excited gold nanospheres with combined quantitative phase imaging. An interferometric photothermal optical lock-in approach (POLI) is shown to improve SNR for detecting nanoparticles (NPs) on multiple substrates, including a monolayer of NPs on a silanized coverslip, and NPs bound to live cells. Furthermore, the set up allowed for co-registered quantitative phase imaging (QPI) to be acquired in an off-axis holographic set-up. An SNR of 103 was obtained for NP-tagging of epidermal growth factor receptor (EGFR) in live cells with a 3 second acquisition, while an SNR of 47 was seen for 20 ms acquisition. An analysis of improvements in SNR due to averaging multiple frames is presented, which suggest that residual photothermal signal can be a limiting factor. The combination of techniques allows for high resolution imaging of cell structure via QPI with the ability to identify receptor expression via POLI. PMID:25136482

  19. Targeting Gold Nanocages to Cancer Cells for Photothermal Destruction and Drug Delivery

    PubMed Central

    Cobley, Claire M.; Au, Leslie; Chen, Jingyi; Xia, Younan

    2009-01-01

    (i) Importance of the field Plasmonic nanoparticles provide a novel route to treat cancer due to their ability to effectively convert light into heat for photothermal destruction. Combined with the targeting mechanisms possible with nanoscale materials, this technique has the potential to enable highly targeted therapies to minimize undesirable side effects. (ii) Areas covered in this review This review discusses the use of gold nanocages, a novel class of plasmonic nanoparticles, for photothermal applications. Gold nanocages are hollow, porous structures with compact sizes, precisely controlled plasmonic properties and surface chemistry. Additionally, we discuss a recent study of gold nanocages as drug-release carriers by externally controlling the opening and closing of the pores with a smart polymer whose conformation changes at a specific temperature. Release of the contents can be initiated remotely through near-infrared irradiation. Together, these topics cover the years from 2002-2009. (iii) What the reader will gain The reader will be exposed to different aspects of gold nanocages, including synthesis, surface modification, in vitro studies, intial in vivo data, and perspectives on future studies. (iv) Take home message Gold nanocages are a promising platform for cancer therapy in terms of both photothermal destruction and drug delivery. PMID:20345327

  20. Photothermal detection of the contrast properties of polypyrrole nanoparticles using optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Kasaragod, Deepa; Au, Kin Man; Lu, Zenghai; Childs, David; Armes, Steven P.; Matcher, Stephen J.

    2013-02-01

    We report on a photothermal modulation detection scheme developed using a swept source-based optical coherence tomography (OCT) system centred at 1300nm. Photothermal detection is an improved technique for studying the contrast properties of exogenous contrast agents such as highly absorbing polypyrrole (PPy) nanoparticles used for OCT imaging. The swept source based OCT system has a wavelength sweep rate of 10 kHz which is used for the phase modulation detection of various concentrations of PPy nanoparticles. PPy nanoparticles have been recently reported to be a promising candidate for OCT imaging owing to their strong NIR absorption from 700-1300nm. Phase-sensitive detection of the photothermal modulation signal is achieved using a pumped 975 nm laser beam at 80Hz and 160Hz for varying concentrations of PPy nanoparticles dispersed in 2% Intralipid phantom. A phase-sensitive detection system is realised by carrying out the phase calibration using the back reflections obtained from the coverslip used with the sample. This study provides quantitative support for the use of PPy nanoparticles as a potential biocompatible contrast agent in OCT imaging.

  1. Manganese doped iron oxide theranostic nanoparticles for combined T1 magnetic resonance imaging and photothermal therapy.

    PubMed

    Zhang, Mengxin; Cao, Yuhua; Wang, Lina; Ma, Yufei; Tu, Xiaolong; Zhang, Zhijun

    2015-03-01

    Photothermal therapy (PTT) is a noninvasive and convenient way to ablate tumor tissues. Integrating PTT with imaging technique could precisely identify the location and the size of tumor regions, thereby significantly improving the therapeutic efficacy. Magnetic resonance imaging (MRI) is widely used in clinical diagnosis due to its superb spatial resolution and real-time monitoring feature. In our work, we developed a theranostic nanoplatform based on manganese doped iron oxide (MnIO) nanoparticles modified with denatured bovine serum albumin (MnIO-dBSA). The in vitro experiment revealed that the MnIO nanoparticles exhibited T1-weighted MRI capability (r1 = 8.24 mM(-1) s(-1), r2/r1 = 2.18) and good photothermal effect under near-infrared laser irradiation (808 nm). Using 4T1 tumor-bearing mice as an animal model, we further demonstrated that the MnIO-dBSA composites could significantly increase T1 MRI signal intensity at the tumor site (about two times) and effectively ablate tumor tissues with photoirradiation. Taken together, this work demonstrates the great potential of the MnIO nanoparticles as an ideal theranostic platform for efficient tumor MR imaging and photothermal therapy. PMID:25672225

  2. Photothermal nanoblade for patterned cell membrane cutting.

    PubMed

    Wu, Ting-Hsiang; Teslaa, Tara; Teitell, Michael A; Chiou, Pei-Yu

    2010-10-25

    We report a photothermal nanoblade that utilizes a metallic nanostructure to harvest short laser pulse energy and convert it into a highly localized and specifically shaped explosive vapor bubble. Rapid bubble expansion and collapse punctures a lightly-contacting cell membrane via high-speed fluidic flows and induced transient shear stress. The membrane cutting pattern is controlled by the metallic nanostructure configuration, laser pulse polarization, and energy. Highly controllable, sub-micron sized circular hole pairs to half moon-like, or cat-door shaped, membrane cuts were realized in glutaraldehyde treated HeLa cells. PMID:21164656

  3. Crack detection by mobile photothermal probe

    SciTech Connect

    Bodnar, J.L.; Egee, M.; Menu, C.; Blanc, A. le; Besnard, R.; Sellier, J.Y.

    1994-12-31

    Within the frame of a previous study, encouraging results were obtained regarding the detection of microcracks by Photo Thermal Radiometry under sinusoidal excitation. However, the used method was too slow for an industrial application. It was therefore necessary to consider faster means of analysis. Such is the object of the present study. The authors show that, by using a mobile photothermal probe displaced relatively to the sample, it is possible to rapidly detect opened or non opened cracks, of a few tens of micrometers wide, and a few hundred of micrometers deep.

  4. Design of Spacecraft Missions to Test Kinetic Impact for Asteroid Deflection

    NASA Technical Reports Server (NTRS)

    Barbee, Brent W.; Hernandez, Sonia

    2012-01-01

    Earth has previously been struck with devastating force by near-Earth asteroids (NEAs) and will be struck again. Telescopic search programs aim to provide advance warning of such an impact, but no techniques or systems have yet been tested for deflecting an incoming NEA. To begin addressing this problem, we have analyzed the more than 8000 currently known NEAs to identify those that offer opportunities for safe and meaningful near-term tests of the proposed kinetic impact asteroid deflection technique. In this paper we present our methodology and results, including complete mission designs for the best kinetic impactor test mission opportunities.

  5. One-pot solventless preparation of PEGylated black phosphorus nanoparticles for photoacoustic imaging and photothermal therapy of cancer.

    PubMed

    Sun, Caixia; Wen, Ling; Zeng, Jianfeng; Wang, Yong; Sun, Qiao; Deng, Lijuan; Zhao, Chongjun; Li, Zhen

    2016-06-01

    Black phosphorus (BP) nanostructures such as nanosheets and nanoparticles have attracted considerable attention in recent years due to their unique properties and great potential in various physical, chemical, and biological fields. In this article, water-soluble and biocompatible PEGylated BP nanoparticles with a high yield were prepared by one-pot solventless high energy mechanical milling technique. The resultant BP nanoparticles can efficiently convert near infrared (NIR) light into heat, and exhibit excellent photostability, which makes them suitable as a novel nanotheranostic agent for photoacoustic (PA) imaging and photothermal therapy of cancer. The in-vitro results demonstrate the excellent biocompatibility of PEGylated BP nanoparticles, which can be used for photothermal ablation of cancer cells under irradiation with NIR light. The in-vivo PA images demonstrate that these BP nanoparticles can be efficiently accumulated in tumors through the enhanced permeability retention effect. The resultant BP nanoparticles can be further utilized for photothermal ablation of tumors by irradiation with NIR light. The tumor-bearing mice were completely recovered after photothermal treatment with BP nanoparticles, in comparison with mice from control groups. Our research highlights the great potential of PEGylated BP nanoparticles in detection and treatment of cancer. PMID:27017578

  6. Recyclable Photo-Thermal Nano-Aggregates of Magnetic Nanoparticle Conjugated Gold Nanorods for Effective Pathogenic Bacteria Lysis.

    PubMed

    Ramasamy, Mohankandhasamy; Kim, Sanghyo; Lee, Su Seong; Yi, Dong Kee

    2016-01-01

    We describe the nucleophilic hybridization technique for fabricating magnetic nanoparticle (MNP) around gold nanorod (AuNR) for desired photo-thermal lysis on pathogenic bacteria. From the electromagnetic energy conversion into heat to the surrounding medium, a significant and quicker temperature rise was noted after light absorption on nanohybrids, at a controlled laser light output and optimum nanoparticle concentration. We observed a similar photo-thermal pattern for more than three times for the same material up on repeated magnetic separation. Regardless of the cell wall nature, superior pathogenic cell lysis has been observed for the bacteria suspensions of individual and mixed samples of Salmonella typhi (S.typhi) and Bacillus subtilis (B.subtilis) by the photo-heated nanoparticles. The synthesis of short gold nanorod, conjugation with magnetic nanoparticle and its subsequent laser exposure provides a rapid and reiterated photo-thermal effect with enhanced magnetic separation for efficient bactericidal application in water samples. Resultant novel properties of the nano-aggregates makes them a candidate to be used for a rapid, effective, and re-iterated photo-thermal agent against a wide variety of pathogens to attain microbe free water. PMID:27398487

  7. Photothermal characterization of sputtered thin films and substrate treatment

    SciTech Connect

    Macedo, F.; Ferreira, J.; Vaz, F.; Rebouta, L.; Daoud, A. Haj; Dietzel, D.; Bein, B. K.

    1999-03-15

    Photothermal radiometry has been applied to relatively thin TiN-based hard coatings on high speed steel. The main results are that the photothermal depth profiles of the samples are strongly influenced by the substrate preparation, that an empirical correlation between the measured photothermal depth profile and different coatings can easily be established, that however a quantitative determination of the thermal properties (thermal diffusivity, effusivity) based on unique solutions of the heat diffusion equation is difficult. This is due to three reasons: the coatings are relatively thin and transparent, and the substrates alone already exhibit strong gradients of the thermal properties.

  8. Laser heterodyne photothermal nondestructive method: extension to transparent probe

    NASA Astrophysics Data System (ADS)

    Pencheva, V.; Penchev, S.; Naboko, V.; Toyoda, K.; Donchev, T.

    2007-03-01

    We present a contribution to the development of the laser heterodyne method of nondestructive material analysis employing photothermal displacement (PTD) probe. PTD is a dominant factor of the photothermal effect in metals and semiconductors, where the derived linear dependence on absorbed energy exhibits a fingerprint of their physical properties. Theoretical consideration of the case of transparent probe is accomplished extending thermal diffusion model. Laser double heterodyne detection is verified for opaque and transparent probes, and in the exclusive case of silicon. The achieved resolution of photothermal displacement is less than 10 -12 m well above the limits of heterodyne measurement.

  9. Photothermal measurement of absorption and scattering losses in thin films excited by surface plasmons.

    PubMed

    Domené, Esteban A; Balzarotti, Francisco; Bragas, Andrea V; Martínez, Oscar E

    2009-12-15

    We present a novel noncontact, photothermal technique, based on the focus error signal of a commercial CD pickup head that allows direct determination of absorption in thin films. Combined with extinction methods, this technique yields the scattering contribution to the losses. Surface plasmon polaritons are excited using the Kretschmann configuration in thin Au films of varying thickness. By measuring the extinction and absorption simultaneously, it is shown that dielectric constants and thickness retrieval leads to inconsistencies if the model does not account for scattering. PMID:20016617

  10. Determination of thermooptical and transport parameters of ε iron(III) oxide-based nanocomposites by beam deflection spectroscopy

    NASA Astrophysics Data System (ADS)

    Korte, Dorota; Carraro, Giorgio; Maccato, Chiara; Franko, Mladen

    2015-04-01

    In this work, photothermal beam deflection (PBD) experiments have been used to characterize the thermooptical and transport properties of ε-Fe2O3-based nanocomposites. In particular, iron(III) nanostructures have been functionalized with Au, Ag and Cu nanoparticles, tailoring both their nano-organization and their chemical state. In order to elucidate the correlation between the thermooptical and transport parameters, the structural, compositional and morphological properties of Fe2O3-based systems were studied by field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). It was observed that the optothermal and transport parameters were influenced by the nature and oxidation state of the nanoparticles, which can serve as a key tool to master the material properties for their application in light-assisted processes.

  11. Multivariate image analysis of laser-induced photothermal imaging used for detection of caries tooth

    NASA Astrophysics Data System (ADS)

    El-Sherif, Ashraf F.; Abdel Aziz, Wessam M.; El-Sharkawy, Yasser H.

    2010-08-01

    Time-resolved photothermal imaging has been investigated to characterize tooth for the purpose of discriminating between normal and caries areas of the hard tissue using thermal camera. Ultrasonic thermoelastic waves were generated in hard tissue by the absorption of fiber-coupled Q-switched Nd:YAG laser pulses operating at 1064 nm in conjunction with a laser-induced photothermal technique used to detect the thermal radiation waves for diagnosis of human tooth. The concepts behind the use of photo-thermal techniques for off-line detection of caries tooth features were presented by our group in earlier work. This paper illustrates the application of multivariate image analysis (MIA) techniques to detect the presence of caries tooth. MIA is used to rapidly detect the presence and quantity of common caries tooth features as they scanned by the high resolution color (RGB) thermal cameras. Multivariate principal component analysis is used to decompose the acquired three-channel tooth images into a two dimensional principal components (PC) space. Masking score point clusters in the score space and highlighting corresponding pixels in the image space of the two dominant PCs enables isolation of caries defect pixels based on contrast and color information. The technique provides a qualitative result that can be used for early stage caries tooth detection. The proposed technique can potentially be used on-line or real-time resolved to prescreen the existence of caries through vision based systems like real-time thermal camera. Experimental results on the large number of extracted teeth as well as one of the thermal image panoramas of the human teeth voltanteer are investigated and presented.

  12. Photothermal effects of immunologically modified carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Griswold, Ryan T.; Henderson, Brock; Goddard, Jessica; Tan, Yongqiang; Hode, Tomas; Liu, Hong; Nordquist, Robert E.; Chen, Wei R.

    2013-02-01

    Carbon nanotubes have a great potential in the biomedical applications. To use carbon nanotubes in the treatment of cancer, we synthesized an immunologically modified single-walled carbon nanotube (SWNT) using a novel immunomodifier, glycated chitosan (GC), as an effective surfactant for SWNT. This new composition SWNT-GC was stable due to the strong non-covalent binding between SWNT and GC. The structure of SWNT-GC is presented in this report. The photothermal effect of SWNT-GC was investigated under irradiation of a near-infrared laser. SWNT-GC retained the optical properties of SWNT and the immunological properties of GC. Specifically, the SWNT-GC could selectively absorb a 980-nm light and induce desirable thermal effects in tissue culture and in animals. It could also induce tumor cell destruction, controlled by the laser settings and the doses of SWNT and GC. Laser+SWNT-GC treatment could also induce strong expression of heat shock proteins on the surface of tumor cells. This immunologically modified carbon nanotube could be used for selective photothermal interactions in noninvasive tumor treatment.

  13. Deflection of a flexural cantilever beam

    NASA Astrophysics Data System (ADS)

    Sherbourne, A. N.; Lu, F.

    The behavior of a flexural elastoplastic cantilever beam is investigated in which geometric nonlinearities are considered. The result of an elastica analysis by Frisch-Fay (1962) is extended to include postyield behavior. Although a closed-form solution is not possible, as in the elastic case, simple algebraic equations are derived involving only one unknown variable, which can also be expressed in the standard form of elliptic integrals if so desired. The results, in comparison with those of the small deflection analyses, indicate that large deflection analyses are necessary when the relative depth of the beam is very small over the length. The present exact solution can be used as a reference by those who resort to a finite element method for more complicated problems. It can also serve as a building block to other beam problems such as a simply supported beam or a beam with multiple loads.

  14. Deflection evaluation using time-resolved radiography

    SciTech Connect

    Fry, D.A.; Lucero, J.P.

    1990-01-01

    Time-resolved radiography is the creation of an x-ray image for which both the start-exposure and stop-exposure times are known with respect to the event under study. The combination of image and timing are used to derive information about the event. We have applied time-resolved radiography to evaluate motions of explosive-driven events. In the particular application discussed here, our intent is to measure maximum deflections of the components involved. Exposures are made during the time just before to just after the event of interest occurs. A smear or blur of motion out to its furthest extent is recorded on the image. Comparison of the dynamic images with static images allows deflection measurements to be made. 2 figs.

  15. AIDA: Asteroid Impact and Deflection Assessment

    NASA Astrophysics Data System (ADS)

    Michel, Patrick; Cheng, A.; Galvez, A.; Reed, C.; Carnelli, I.; Abell, P.; Ulamec, S.; Rivkin, A.; Biele, J.; Murdoch, N.

    2015-03-01

    AIDA (Asteroid Impact and Deflection Assessment) is a project of a joint mission demonstration of asteroid deflection and characterisation of the kinetic impact effects. It involves the Johns Hopkins Applied Physics Laboratory (with support from members of NASA centers including Goddard Space Flight Center, Johnson Space Center, and the Jet Propulsion Laboratory), and the European Space Agency (with support from members of the french CNRS/Cte dAzur Observatory and the german DLR). This assessment will be done using a binary asteroid target. AIDA consists of two independent but mutually supporting mission concepts, one of which is the asteroid kinetic impactor and the other is the characterisation spacecraft. The objective and status of the project will be presented.

  16. Dark matter prospects in deflected mirage mediation

    NASA Astrophysics Data System (ADS)

    Holmes, Michael; Nelson, Brent D.

    2009-07-01

    The recently introduced deflected mirage mediation (DMM) model is a string-motivated paradigm in which all three of the major supersymmetry-breaking transmission mechanisms are operative. We begin a systematic exploration of the parameter space of this rich model context, paying special attention to the pattern of gaugino masses which arise. In this work we focus on the dark matter phenomenology of the DMM model as such signals are the least influenced by the model-dependent scalar masses. We find that a large portion of the parameter space in which the three mediation mechanisms have a similar effective mass scale of 1 TeV or less will be probed by future direct and indirect detection experiments. Distinguishing deflected mirage mediation from the mirage model without gauge mediation will prove difficult without collider input, though we indicate how gamma ray signals may provide an opportunity for distinguishing between the two paradigms.

  17. Compact Superconducting Crabbing and Deflecting Cavities

    SciTech Connect

    De Silva, Payagalage Subashini Uddika

    2012-09-01

    Recently, new geometries for superconducting crabbing and deflecting cavities have been developed that have significantly improved properties over those the standard TM{sub 110} cavities. They are smaller, have low surface fields, high shunt impedance and, more importantly for some of them, no lower-order-mode with a well-separated fundamental mode. This talk will present the status of the development of these cavities.

  18. Polyhedron tracking and gravity tractor asteroid deflection

    NASA Astrophysics Data System (ADS)

    Ummen, N.; Lappas, V.

    2014-11-01

    In the wake of the Chelyabinsk airburst, the defense against hazardous asteroids is becoming a topic of high interest. This work improves the gravity tractor asteroid deflection approach by tracking realistic small body shapes with tilted ion engines. An algorithm for polyhedron tracking was evaluated in a fictitious impact scenario. The simulations suggest a capability increase up to 38.2% with such improved tilting strategies. The long- and short-term effects within polyhedron tracking are illustrated. In particular, the orbital reorientation effect is influential when realistic asteroid shapes and rotations are accounted for. Also analyzed is the subject of altitude profiles, a way to tailor the gravity tractor performance, and to achieve a steering ability within the B-plane. A novel analytical solution for the classic gravity tractor is derived. It removes the simulation need for classic tractor designs to obtain comparable two body model Δv figures. This paper corroborates that the asteroid shape can be exploited for maximum performance. Even a single engine tilt adjustment at the beginning of deflection operations yields more deflection than a fixed preset tilt.

  19. Photothermally activated motion and ignition using aluminum nanoparticles

    SciTech Connect

    Abboud, Jacques E.; Chong Xinyuan; Zhang Mingjun; Zhang Zhili; Jiang Naibo; Roy, Sukesh; Gord, James R.

    2013-01-14

    The aluminum nanoparticles (Al NPs) are demonstrated to serve as active photothermal media, to enhance and control local photothermal energy deposition via the photothermal effect activated by localized surface plasmon resonance (LSPR) and amplified by Al NPs oxidation. The activation source is a 2-AA-battery-powered xenon flash lamp. The extent of the photothermally activated movement of Al NPs can be {approx}6 mm. Ignition delay can be {approx}0.1 ms. Both scanning electron microscopy and energy-dispersive X-ray spectroscopy measurements of motion-only and after-ignition products confirm significant Al oxidation occurs through sintering and bursting after the flash exposure. Simulations suggest local heat generation is enhanced by LSPR. The positive-feedback effects from the local heat generation amplified by Al oxidation produce a large increase in local temperature and pressure, which enhances movement and accelerates ignition.

  20. Photo-thermal processing of semiconductor fibers and thin films

    NASA Astrophysics Data System (ADS)

    Gupta, Nishant

    Furnace processing and rapid thermal processing (RTP) have been an integral part of several processing steps in semiconductor manufacturing. The performance of RTP techniques can be improved many times by exploiting quantum photo-effects of UV and vacuum ultraviolet (VUV) photons in thermal processing and this technique is known as rapid photo-thermal processing (RPP). As compared to furnace processing and RTP, RPP provides higher diffusion coefficient, lower stress and lower microscopic defects. In this work, a custom designed automated photo assisted processing system was built from individual parts and an incoherent light source. This photo-assisted processing system is used to anneal silica clad silicon fibers and deposit thin-films. To the best of our knowledge, incoherent light source based rapid photo-thermal processing (RPP) was used for the first time to anneal glass-clad silicon core optical fibers. X-ray diffraction examination, Raman spectroscopy and electrical measurements showed a considerable enhancement of structural and crystalline properties of RPP treated silicon fibers. Photons in UV and vacuum ultraviolet (VUV) regions play a very important role in improving the bulk and carrier transport properties of RPP-treated silicon optical fibers, and the resultant annealing permits a path forward to in situ enhancement of the structure and properties of these new crystalline core optical fibers. To explore further applications of RPP, thin-films of Calcium Copper Titanate (CaCu3Ti4O12) or CCTO and Copper (I) Oxide (Cu2O) were also deposited using photo-assisted metal-organic chemical vapor deposition (MOCVD) on Si/SiO2 and n-Si substrate respectively. CCTO is one of the most researched giant dielectric constant materials in recent years. The given photo-assisted MOCVD approach provided polycrystalline CCTO growth on a SiO2 surface with grain sizes as large as 410 nm. Copper (I) oxide (Cu2O) is a direct band gap semiconductor with p-type conductivity and

  1. Erythrocyte membrane is an alternative coating to polyethylene glycol for prolonging the circulation lifetime of gold nanocages for photothermal therapy.

    PubMed

    Piao, Ji-Gang; Wang, Limin; Gao, Feng; You, Ye-Zi; Xiong, Yujie; Yang, Lihua

    2014-10-28

    Gold nanocages (AuNCs), which have tunable near-infrared (NIR) absorption and intrinsically high photothermal conversion efficiency, have been actively investigated as photothermal conversion agents for photothermal therapy (PTT). The short blood circulation lifetime of AuNCs, however, limits their tumor uptake and thus in vivo applications. Here we show that such a limitation can be overcome by cloaking AuNCs with red blood cell (RBC) membranes, a natural stealth coating. The fusion of RBC membranes over AuNC surface does not alter the unique porous and hollow structures of AuNCs, and the resulting RBC-membrane-coated AuNCs (RBC-AuNCs) exhibit good colloidal stability. Upon NIR laser irradiation, the RBC-AuNCs demonstrate in vitro photothermal effects and selectively ablate cancerous cells within the irradiation zone as do the pristine biopolymer-stealth-coated AuNCs. Moreover, the RBC-AuNCs exhibit significantly enhanced in vivo blood retention and circulation lifetime compared to the biopolymer-stealth-coated counterparts, as demonstrated using a mouse model. With integrated advantages of photothermal effects from AuNCs and long blood circulation lifetime from RBCs, the RBC-AuNCs demonstrate drastically enhanced tumor uptake when administered systematically, and mice that received PPT cancer treatment modulated by RBC-AuNCs achieve 100% survival over a span of 45 days. Taken together, our results indicate that the long circulating RBC-AuNCs may facilitate the in vivo applications of AuNCs, and the RBC-membrane stealth coating technique may pave the way to improved efficacy of PPT modulated by noble metal nanoparticles. PMID:25286086

  2. Fabrication and Testing of Deflecting Cavities for APS

    SciTech Connect

    Mammosser, John; Wang, Haipeng; Rimmer, Robert; Jim, Henry; Katherine, Wilson; Dhakal, Pashupati; Ali, Nassiri; Jim, Kerby; Jeremiah, Holzbauer; Genfa, Wu; Joel, Fuerst; Yawei, Yang; Zenghai, Li

    2013-09-01

    Jefferson Lab (Newport News, Virginia) in collaboration with Argonne National Laboratory (Argonne, IL) has fabricated and tested four first article, 2.8 GHz, deflecting SRF cavities, for Argonne's Short-Pulse X-ray (SPX) project. These cavities are unique in many ways including the fabrication techniques in which the cavity cell and waveguides were fabricated. These cavity subcomponents were milled from bulk large grain niobium ingot material directly from 3D CAD files. No forming of sub components was used with the exception of the beam-pipes. The challenging cavity and helium vessel design and fabrication results from the stringent RF performance requirements required by the project and operation in the APS ring. Production challenges and fabrication techniques as well as testing results will be discussed in this paper.

  3. Effect of electrical spot welding on load deflection rate of orthodontic wires

    PubMed Central

    Alavi, Shiva; Abrishami, Arezoo

    2015-01-01

    Background: One of the methods used for joining metals together is welding, which can be carried out using different techniques such as electric spot welding. This study evaluated the effect of electric spot welding on the load deflection rate of stainless steel and chromium-cobalt orthodontic wires. Materials and Methods: In this experimental-laboratory study, load deflection rate of 0.016 × 0.022 inch stainless steel and chromium cobalt wires were evaluated in five groups (n =18): group one: Stainless steel wires, group two: chromium-cobalt wires, group three: stainless steel wires welded to stainless steel wires, group four: Stainless steel wires welded to chromium-cobalt wires, group five: chromium-cobalt wire welded to chromium-cobalt wires. Afterward, the forces induced by the samples in 0.5 mm, 1 mm, 1.5 mm deflection were measured using a universal testing machine. Then mean force measured for each group was compared with other groups. The data were analyzed using repeated measure analysis of variance (ANOVA), one-way ANOVA, and paired t-test by the SPSS software. The significance level was set as 0.05. Results: The Tukey test showed that there were significant differences between the load deflection rates of welded groups compared to control ones (P < 0.001). Conclusion: Considering the limitation of this study, the electric spot welding process performed on stainless steel and chromium-cobalt wires increased their load deflection rates. PMID:26604957

  4. Photothermal degradation of ethylene/vinylacetate copolymer

    NASA Technical Reports Server (NTRS)

    Liang, R. H.; Chung, S.; Clayton, A.; Di Stefano, S.; Oda, K.; Hong, S. D.; Gupta, A.

    1983-01-01

    Photothermal degradation studies were conducted on a 'stabilized' formulation of ethylene/vinyl acetate copolymer (EVA) in the temperature range 25-105 C under three different oxygen environments (in open air, with limited access to O2, and in a dark closed stagnant oven). These studies were performed in order to evaluate the utility of EVA as an encapsulation material for photovoltaic modules. Results showed that at low temperature (25 C), slow photooxidation of the polymer occurred via electronic energy transfer involving the UV absorber incorporated in the polymer. However, no changes in the physical properties of the bulk polymer were detected up to 1500 hours of irradiation. At elevated temperatures, leaching and evaporation of the additives occurred, which ultimately resulted in the chemical crosslinking of the copolymer and the formation of volatile photoproducts such as acetic acid.

  5. Gaussian beam photothermal single particle microscopy.

    PubMed

    Selmke, Markus; Braun, Marco; Cichos, Frank

    2012-10-01

    We explore the intuitive lensing picture of laser-heated nanoparticles occurring in single particle photothermal (PT) microscopy. The effective focal length of the thermal lens (TL) is derived from a ray-optics treatment and used to transform the probing focused Gaussian beam with ABCD Gaussian matrix optics. The relative PT signal is obtained from the relative beam-waist change far from the TL. The analytical expression is semiquantitative, capable of describing the entire phenomenology of single particle PT microscopy, and shows that the signal is the product of the point-spread functions of the involved lasers times a linear function of the axial coordinate. The presented particularly simple and intuitive Gaussian beam lensing picture compares favorably to the experimental results for 60 nm gold nanoparticles and provides the prescription for optimum setup calibration. PMID:23201674

  6. Gravitational lensing from compact bodies: Analytical results for strong and weak deflection limits

    SciTech Connect

    Amore, Paolo; Cervantes, Mayra; De Pace, Arturo; Fernandez, Francisco M.

    2007-04-15

    We develop a nonperturbative method that yields analytical expressions for the deflection angle of light in a general static and spherically symmetric metric. The method works by introducing into the problem an artificial parameter, called {delta}, and by performing an expansion in this parameter to a given order. The results obtained are analytical and nonperturbative because they do not correspond to a polynomial expression in the physical parameters. Already to first order in {delta} the analytical formulas obtained using our method provide at the same time accurate approximations both at large distances (weak deflection limit) and at distances close to the photon sphere (strong deflection limit). We have applied our technique to different metrics and verified that the error is at most 0.5% for all regimes. We have also proposed an alternative approach which provides simpler formulas, although with larger errors.

  7. Photothermal modification of optical microscope for noninvasive living cell monitoring

    NASA Astrophysics Data System (ADS)

    Lapotko, Dmitry; Romanovskaya, Tat'yana; Zharov, Vladimir P.

    2001-06-01

    Photothermal method was applied to improve sensing and imaging capabilities of a light microscope in cell studies. We describe the methods, technical details and testing results of cytometric application of Laser Photothermal Phase Microscope (LPPM). The merits of the proposed approach include living single cell monitoring capability, quantitative measurement of cell functional features through the use of cell natural chromophores as the sensors. Such intracellular sensors are activated by the laser pulse and transform an absorbed energy into the heat. The latter causes thermal and mechanical loads to a cell and its components. The second stage of the process includes the reaction of the cell as integral system or of its components to such loads. This reaction is caused by the changes of cell functional and structural state and includes alterations of cell optical properties. Both processes are monitored for a single cell non-invasively with probe laser beam. Pulsed phase contrast dual beam illumination scheme with acquisition of several laser images at different stages of cell-laser interaction was introduced. An acquired cell image is considered as spatially and temporally resolved cell response to non-specific load that is induced in a cell with a pump laser. This method eliminates any cell staining and allows to monitor cell viability and cell reaction to the environmental factors. Also LPPM offers further improvement of spatial and temporal resolution of optical microscope: with pulsed probe laser monitoring we can detect components with the size down to 50 nm and temporal resolution of 10 ns. In our set up the cell is pumped by pulsed laser at 532 nm, 10 ns , 0.01-0.4 mJ. The source of probe beam is a pulsed dye laser (630 nm, 10 nJ, 10 ns) which forms cell phase image. The results obtained with living cells such as drug impact control, single cell dosimetry, immune action of light on a cell demonstrate basic features of LPPM as the tool for the study of the

  8. Designs of Superconducting Parallel-Bar Deflecting Cavities for Deflecting/Crabbing Applications

    SciTech Connect

    Delayen, J. R.; De Silva, S. U.

    2011-07-01

    The superconducting parallel-bar cavity is a deflecting/crabbing cavity with attractive properties, compared to other conventional designs, that is currently being considered for a number of applications. The new parallel-bar design with curved loading elements and circular or elliptical outer conductors have improved properties compared to the designs with rectangular outer conductors. We present the designs proposed as deflecting cavities for the Jefferson Lab 12 GeV upgrade and for Project-X and as crabbing cavities for the proposed LHC luminosity upgrade and electron-ion collider at Jefferson Lab.

  9. Measurement of thermal diffusivity, elastic anisotropy and crystallographic orientation by interferometric photothermal microscopy

    NASA Astrophysics Data System (ADS)

    Jumel, Julien; Rochais, Denis

    2007-07-01

    This paper describes the use of interferometric photothermal microscopy for measuring the thermal diffusivity, crystallographic orientation and elastic anisotropy of a microscopic homogeneous volume of matter. This purely optical technique makes use of an intensity-modulated and focused laser beam to periodically heat the surface of the sample tested. An interferometer is used to detect the thermal expansion. After describing the experimental setup, we explain the inversion scheme allowing the determination of the local thermal diffusivity from the periodic sample surface displacement map, as well as the crystallographic orientation and elastic anisotropy in the case of cubic materials. These parameters are measured with a spatial resolution of a few cubic micrometres.

  10. Sensitive absorption measurements in bulk material and coatings using a photothermal and a photoacoustic spectrometer

    NASA Astrophysics Data System (ADS)

    Fieberg, S.; Waasem, N.; Kühnemann, F.; Buse, K.

    2014-02-01

    Bulk and surface absorption in lithium triborate (LBO) and lithium niobate (LiNbO3) are measured using two sensitive measurement techniques, a photoacoustic spectrometer (PAS) and a photothermal common-path interferometer (PCI). As pump light sources, optical parametric oscillators are employed, covering the wavelength ranges 212 - 2500 nm (PAS) and 1460 - 1900 nm and 2460 - 3900 nm (PCI). The spectrometers are used to measure absorption spectra of optical materials across this wide spectral range and to compare the methods in the shared wavelength regime.

  11. Depth-resolved analytical model and correction algorithm for photothermal optical coherence tomography

    PubMed Central

    Lapierre-Landry, Maryse; Tucker-Schwartz, Jason M.; Skala, Melissa C.

    2016-01-01

    Photothermal OCT (PT-OCT) is an emerging molecular imaging technique that occupies a spatial imaging regime between microscopy and whole body imaging. PT-OCT would benefit from a theoretical model to optimize imaging parameters and test image processing algorithms. We propose the first analytical PT-OCT model to replicate an experimental A-scan in homogeneous and layered samples. We also propose the PT-CLEAN algorithm to reduce phase-accumulation and shadowing, two artifacts found in PT-OCT images, and demonstrate it on phantoms and in vivo mouse tumors. PMID:27446693

  12. Measurement of the optical and thermal properties of biliary calculi using pulsed photothermal radiometry

    SciTech Connect

    Long, F.H.; Nishioka, N.S.; Deutsch, T.F.

    1987-01-01

    The optical absorption coefficients for biliary calculi are important in understanding the mechanism of laser-induced stone fragmentation. However, the heterogeneous composition of calculi and difficulties in producing optically thin samples prevent conventional spectrophotometric measurement techniques from being used. To overcome these limitations, we used a pulsed photothermal radiometry system to measure the optical absorption coefficients and thermal diffusivities of various biliary calculi. In the wavelength range examined (350-1060 nm), there was strong optical absorption which was greater for pigment stones than for cholesterol stones. The data support the theory that the initiation of the plasma accompanying laser fragmentation of calculi is a thermal process.

  13. Single-particle absorption spectroscopy by photothermal contrast.

    PubMed

    Yorulmaz, Mustafa; Nizzero, Sara; Hoggard, Anneli; Wang, Lin-Yung; Cai, Yi-Yu; Su, Man-Nung; Chang, Wei-Shun; Link, Stephan

    2015-05-13

    Removing effects of sample heterogeneity through single-molecule and single-particle techniques has advanced many fields. While background free luminescence and scattering spectroscopy is widely used, recording the absorption spectrum only is rather difficult. Here we present an approach capable of recording pure absorption spectra of individual nanostructures. We demonstrate the implementation of single-particle absorption spectroscopy on strongly scattering plasmonic nanoparticles by combining photothermal microscopy with a supercontinuum laser and an innovative calibration procedure that accounts for chromatic aberrations and wavelength-dependent excitation powers. Comparison of the absorption spectra to the scattering spectra of the same individual gold nanoparticles reveals the blueshift of the absorption spectra, as predicted by Mie theory but previously not detectable in extinction measurements that measure the sum of absorption and scattering. By covering a wavelength range of 300 nm, we are furthermore able to record absorption spectra of single gold nanorods with different aspect ratios. We find that the spectral shift between absorption and scattering for the longitudinal plasmon resonance decreases as a function of nanorod aspect ratio, which is in agreement with simulations. PMID:25849105

  14. Photoacoustically-guided photothermal killing of mosquitoes targeted by nanoparticles.

    PubMed

    Foster, Stephen R; Galanzha, Ekaterina I; Totten, Daniel C; Beneš, Helen; Shmookler Reis, Robert J; Zharov, Vladimir P

    2014-07-01

    In biomedical applications, nanoparticles have demonstrated the potential to eradicate abnormal cells in small localized pathological zones associated with cancer or infections. Here, we introduce a method for nanotechnology-based photothermal (PT) killing of whole organisms considered harmful to humans or the environment. We demonstrate that laser-induced thermal, and accompanying nano- and microbubble phenomena, can injure or kill C. elegans and mosquitoes fed carbon nanotubes, gold nanospheres, gold nanoshells, or magnetic nanoparticles at laser energies that are safe for humans. In addition, a photoacoustic (PA) effect was used to control nanoparticle delivery. Through the integration of this technique with molecular targeting, nanoparticle clustering, magnetic capturing and spectral sharpening of PA and PT plasmonic resonances, our laser-based PA-PT nano-theranostic platform can be applied to detection and the physical destruction of small organisms and carriers of pathogens, such as malaria vectors, spiders, bed bugs, fleas, ants, locusts, grasshoppers, phytophagous mites, or other arthropod pests, irrespective of their resistance to conventional treatments. PMID:23450780

  15. Photothermal spectroscopy of II-VI mixed crystals

    NASA Astrophysics Data System (ADS)

    Zakrzewski, Jacek

    2005-09-01

    Wide gap II-VI semiconducting mixed crystals are extensively studied during the past few years as they are promising candidates for applications in construction photo and electrooptical devices operating in blue-green and UV spectral region. The high degree of covalent bonding of Be chalcogenides leads to increase of their lattice rigidity. For this reason, mixing of Be chalcogenides with other wide gap II-VI binary compounds would increase the resistance of the optoelectronic structure to defect generation and propagation. The photoacoustic spectroscopy has been developed to investigate the thermal and optical properties of semiconductors since it is very sensitive and complementary method to the absorption and photoluminescence spectroscopy. The modified Jackson - Amer model is used to interpret the obtained spectra for the piezoelectric photothermal technique. From the amplitude spectra of the piezoelectric signal, the method enables computation of the optical absorption coefficient spectra and estimation of the energy gap values of the investigated samples. It also enables the determination of the thermal diffusivity values of the samples from the analysis of the piezoelectric phase signal. In special cases, the multi-layer model, developed very recently, can be applied for the interpretation of experimental spectra. The influence of the annealing process of II-VI samples in cation vapor on the amplitude photoacoustic spectra in the saturation region is shown and discussed. The values of the parameter η (efficiency of the nonradiative recombination processes) for both, as grown and annealed crystals were determined and discussed.

  16. Deflection of Propeller Blades While Running

    NASA Technical Reports Server (NTRS)

    Katzmayr, R

    1922-01-01

    The forces acting on the blades of a propeller proceed from the mass of the propeller and the resistance of the surrounding medium. The magnitude, direction and point of application of the resultant to the propeller blade is of prime importance for the strength calculation. Since it was obviously impracticable to bring any kind of testing device near the revolving propeller, not so much on account of the element of danger as on account of the resulting considerable disturbance of the air flow, the deflection in both cases was photographically recorded and subsequently measured at leisure.

  17. Dark matter signals in deflected mirage mediation

    SciTech Connect

    Holmes, Michael

    2010-02-10

    We investigate the parameter space of a specific class of model within the deflected mirage mediation (DMM) scenario. We look at neutralino properties and compute the thermal relic density as well as interaction rates with xenon direct detection experiments. We find that there are portions of the parameter space which are in line with the current WMAP constraints. Further we find that none of the investigated parameter space is in conflict with current bounds from the Xenon10 experiment and that future large-scale liquid xenon experiments will probe a large portion of the model space.

  18. Electroweak naturalness and deflected mirage mediation

    NASA Astrophysics Data System (ADS)

    Barger, Vernon; Everett, Lisa L.; Garon, Todd S.

    2016-04-01

    We investigate the question of electroweak naturalness within the deflected mirage mediation (DMM) framework for supersymmetry breaking in the minimal supersymmetric standard model. The class of DMM models considered are nine-parameter theories that fall within the general classification of the 19-parameter phenomenological minimal supersymmetric standard model. Our results show that these DMM models have regions of parameter space with very low electroweak fine-tuning, at levels comparable to the phenomenological minimal supersymmetric standard model. These parameter regions should be probed extensively in the current LHC run.

  19. DEFLECTION MEASUREMENTS OF 25 mm ALUMINUM COLLARS

    SciTech Connect

    Peters, C.

    1984-10-01

    This report is a summary of mechanical load-deflection tests performed on prototype collars. The individual collar plates were N.C. machined from 0.125 inch thick 7075-T6 aluminum alloy plate. Inside corners were finished by EDM and outside corners and keyways were finished with an end milling operation. The last step was done with all the individual collar plates (98 pieces) assembled on pins to form the cross section shown in Fig. 1. Figure 1 also shows some of the basic collar dimensions.

  20. Biomimetic Strategies Employed in the Formation of Biotargeted Metal Nanoparticles for Optical Imaging and Photothermal Therapy

    NASA Astrophysics Data System (ADS)

    Black, Kvar Carl Lee, IV

    Diseases resistant to current treatment protocols like chemo resistant cancers and antibiotic resistant bacterial infections require treatments with novel mechanisms of action. Metal nanoparticles (NPs) have unique dielectric properties that give rise to the surface plasmon resonance (SPR), which causes these materials to interact strongly with light. With multifunctional surface modifications, metal NPs have the potential to diagnose and treat diseases like cancer and bacterial infections with optical imaging techniques and light-activated photothermal therapy. With the ability to interact strongly with metals and organics, versatile catecholamine molecules inspired by marine mussels can be used to synthesize metal NPs and functionalize them with a variety of molecules. With this biomimetic tool, these metal NPs can be formed and stabilized in physiological environments and functionalized to specifically target diseased cell surfaces. Herein, molecules containing catechols and amines are used to form gold and silver NPs and tune their SPR optical properties throughout the visible and near-infrared (NIR) region of the electromagnetic spectrum with shape and compositional control. A variety of chemical mechanisms including catechol redox activity are employed in the metal NP formation and functionalization to engineer robust metal-organic interfaces for biomedical applications. Antibodies are functionalized onto metal NPs to provide specific targeting to cancer and bacterial cell surfaces. For cancer, the epidermal growth factor receptor, overexpressed in a variety of cancers, is targeted in oral and breast cancer cells. For bacteria, NPs are targeted to endotoxins on gram-negative escherichia coli membranes and lipoteichoic acids in gram-positive staphylococcus epidermidis cell walls. Optical techniques including optical coherence tomography (OCT) and bright field microscopy are used to identify NPs on cells, and photothermal therapy is successfully demonstrated

  1. Polypyrrole Composite Nanoparticles with Morphology-Dependent Photothermal Effect and Immunological Responses.

    PubMed

    Tian, Ye; Zhang, Jianping; Tang, Shiwei; Zhou, Lei; Yang, Wuli

    2016-02-10

    Polypyrrole composite nanoparticles with controlled shape are synthesized, which exhibit a morphology-dependent photothermal effect: the raspberry-like composite nanoparticles have a much better photothermal effect than the spherical ones, and the immune responses to the nanocomposites are also dependent on their morphology. The outstanding performance of the nanocomposites promises their potential application in photothermal therapy and immunotherapy of cancer. PMID:26701670

  2. Three-dimensional diamagnetic particle deflection in ferrofluid microchannel flows

    PubMed Central

    Liang, Litao; Zhu, Junjie; Xuan, Xiangchun

    2011-01-01

    Magnetic field-induced particle manipulation is a promising technique for biomicrofluidics applications. It is simple, cheap, and also free of fluid heating issues that accompany other common electric, acoustic, and optical methods. This work presents a fundamental study of diamagnetic particle motion in ferrofluid flows through a rectangular microchannel with a nearby permanent magnet. Due to their negligible magnetization relative to the ferrofluid, diamagnetic particles experience negative magnetophoresis and are repelled away from the magnet. The result is a three-dimensionally focused particle stream flowing near the bottom outer corner of the microchannel that is the farthest to the center of the magnet and hence has the smallest magnetic field. The effects of the particle’s relative position to the magnet, particle size, ferrofluid flow rate, and concentration on this three-dimensional diamagnetic particle deflection are systematically studied. The obtained experimental results agree quantitatively with the predictions of a three-dimensional analytical model. PMID:22662037

  3. Relationship between frequency and deflection angle in the DNA prism.

    PubMed

    Chen, Zhen; Dorfman, Kevin D

    2013-01-01

    The DNA prism is a modification of the standard pulsed-field electrophoresis protocol to provide a continuous separation, where the DNA are deflected at an angle that depends on their molecular weight. The standard switchback model for the DNA prism predicts a monotonic increase in the deflection angle as a function of the frequency for switching the field until a plateau regime is reached. However, experiments indicate that the deflection angle achieves a maximum value before decaying to a size-independent value at high frequencies. Using Brownian dynamics simulations, we show that the maximum in the deflection angle is related to the reorientation time for the DNA and the decay in deflection angle at high frequencies is due to inadequate stretching. The generic features of the dependence of the deflection angle on molecular weight, switching frequency, and electric field strength explain a number of experimental phenomena. PMID:23410375

  4. Laser photothermal radiometric instrumentation for fast in-line industrial steel hardness inspection and case depth measurements

    SciTech Connect

    Guo Xinxin; Sivagurunathan, Konesh; Garcia, Jose; Mandelis, Andreas; Giunta, Salvatore; Milletari, Salvatore

    2009-03-01

    A contact-free, nondestructive laser photothermal radiometric instrumentation technique was developed to meet industrial demand for on-line steel hardness inspection and quality control. A series of industrial steel samples, flat or curvilinear, with different effective hardness case depths ranging between 0.21 and 1.78 mm were measured. The results demonstrated that three measurement parameters (metrics) extracted from fast swept-sine photothermal excitation and measurements, namely, the phase minimum frequency fmin, the peak or trough frequency width W, and the area S, are complementary for evaluating widely different ranges of hardness case depth: fmin is most suitable for large case depths, and W and S for small case depths. It was also found that laser beam angular inclination with respect to the surface plane of the sample strongly affects hardness measurement resolution and that the phase frequency maximum is more reliable than the amplitude maximum for laser beam focusing on the sample surface.

  5. Photoacoustic- and Magnetic Resonance-Guided Photothermal Therapy and Tumor Vasculature Visualization Using Theranostic Magnetic Gold Nanoshells.

    PubMed

    Zhou, Min; Singhana, Burapol; Liu, Yang; Huang, Qian; Mitcham, Trevor; Wallace, Michael J; Stafford, R Jason; Bouchard, Richard R; Melancon, Marites P

    2015-08-01

    Nanoparticle based image-guided therapy is an emerging technology for cancer in recent years. Here, we report simultaneous photoacoustic (PA)- and magnetic resonance (MR)-guided photothermal ablation (PTA) therapy using multifunctional superparamagnetic iron oxide-containing gold nanoshells (SPIO@AuNS). Based on the intrinsic high near-infrared optical absorbance and strong magnetic property of SPIO@AuNS, we carried out in vivo dual-modality PA-MR imaging of mouse tumors. PA- and MR-guided imaging can monitor therapeutic effect after photothermal therapy mediated by our multifunctional nanomaterial. In addition, using our pulsed laser PA technique, we also observe a clearer structure of the tumor vasculature after intravenously administration SPIO@AuNS. The novel dual PA-MRI image-guided PTA therapy provides a promising new platform for cancer diagnosis and treatment simultaneously. PMID:26295144

  6. Cu7 S4 Nanosuperlattices with Greatly Enhanced Photothermal Efficiency.

    PubMed

    Cui, Jiabin; Jiang, Rui; Xu, Suying; Hu, Gaofei; Wang, Leyu

    2015-09-01

    According to the simulation, the self-assembly of Cu7 S4 nanocrystals would enhance the photothermal conversion efficiency (PCE) because of the localized surface plasmon resonance effects, which is highly desirable for photothermal therapy (PTT). A new strategy to synthesize Cu7 S4 nanosuperlattices with greatly enhanced PCE up to 65.7% under irradiation of 808 nm near infrared light is reported here. By tuning the surface properties of Cu7 S4 nanocrystals during the synthesis via thermolysis of a new single precursor, dispersed nanoparticles (NPs), rod-like alignments, and nanosuperlattices are obtained, respectively. To explore their PTT applications, these hydrophobic nanostructures are transferred into water by coating with home-made amphiphilic polymer while maintaining their original structures. Under identical conditions, the PCE are 48.62% and 56.32% for dispersed NPs and rod-like alignments, respectively. As expected, when the nanoparticles are self-assembled into nanosuperlattices, the PCE is greatly enhanced up to 65.7%. This strong PCE, along with their excellent photothermal stability and good biocompatibility, renders these nanosuperlattices good candidates as PTT agents. In vitro photothermal ablation performances have undoubtedly proved the excellent PCE of our Cu7 S4 nanosuperlattices. This research offers a versatile and effective solution to get PTT agents with high photothermal efficiency. PMID:25981697

  7. Gold nanorods carrying paclitaxel for photothermal-chemotherapy of cancer.

    PubMed

    Ren, Fei; Bhana, Saheel; Norman, Derek D; Johnson, Jermaine; Xu, Lijing; Baker, Daniel L; Parrill, Abby L; Huang, Xiaohua

    2013-03-20

    Nanotechnology-based photothermal therapy has emerged as a promising treatment for cancer during the past decade. However, heterogeneous laser heating and limited light penetration can lead to incomplete tumor cell eradication. Here, we developed a method to overcome these limitations by combining chemotherapy with photothermal therapy using paclitaxel-loaded gold nanorods. Paclitaxel was loaded to gold nanorods with high density (2.0 × 10(4) paclitaxel per gold nanorod) via nonspecific adsorption, followed by stabilization with poly(ethylene glycol) linked with 11-mercaptoundecanoic acid. Paclitaxel was entrapped in the hydrophobic pocket of the polymeric monolayer on the surface of gold nanorods, which allows direct cellular delivery of the hydrophobic drugs via the lipophilic plasma membrane. Highly efficient drug release was demonstrated in a cell membrane mimicking two-phase solution. Combined photothermal therapy and chemotherapy with the paclitaxel-loaded gold nanorods was shown to be highly effective in killing head and neck cancer cells and lung cancer cells, superior to photothermal therapy or chemotherapy alone due to a synergistic effect. The paclitaxel-gold nanorod enabled photothermal chemotherapy has the potential of preventing tumor reoccurrence and metastasis and may have an important impact on the treatment of head and neck cancer and other malignancies in the clinic. PMID:23360450

  8. Beam-beam deflection and signature curves for elliptic beams

    SciTech Connect

    Ziemann, V.

    1990-10-22

    In this note we will present closed expressions for the beam-beam deflection angle for arbitrary elliptic beams including tilt. From these expressions signature curves, i.e., systematic deviations from the round beam deflection curve due to ellipticity or tilt are derived. In the course of the presentation we will prove that it is generally impossible to infer individual beam sizes from beam-beam deflection scans. 3 refs., 2 figs.

  9. Determination of peak deflections from human surrogates using chestbands in side impact tests.

    PubMed

    Yoganandan, Narayan; Humm, John R; Pintar, Frank A; Maiman, Dennis J

    2013-08-01

    To understand the biomechanics of the human body in motor vehicle environments, physical models including anthropomorphic test devices (ATD) and biological models (postmortem human surrogates) are used, and sled tests are conducted. Deflection is often used as a biomechanical variable to characterize the effects of impact loading and derive injury criteria. The objective of the present study was to evaluate different techniques and recommend a methodology to determine the peak thorax and abdominal deflections from temporal contours using chestbands in oblique lateral impacts. The side impact ATD WorldSID representing human surrogates was positioned on a seat. The seat was rigidly fixed to the platform of an acceleration sled. The oblique load-wall fixed to the sled consisted of separate and adjustable plates to contact the shoulder, thorax, abdomen, and pelvis. Two 59-gage chestbands were wrapped on the thorax and abdomen. Tests were conducted at low, medium, and high velocities (3.4, 6.7, and 7.5m/s) and three methods, termed the spine-sternum, bilateral, and spine-box, were used to determine the global peak deflection and its angulation. Results indicated that all three methods produced very similar angulations, for all velocity tests, and at both thorax and abdominal regions. However, maximum deflections were the lowest in the spine-sternum, followed by bilateral and spine-box methods, with one exception. Based on the development of deflection contours, locations used in the definitions of the origin, and accuracy in identifying critical locations/points in time-varying contours, results of the present study indicate that the bilateral method is the optimum procedure to determine the oblique peak deflection vector in biomechanical tests. PMID:23357337

  10. A non-contact temperature measurement system for controlling photothermal medical laser treatments

    NASA Astrophysics Data System (ADS)

    Kaya, Ã.-zgür; Gülsoy, Murat

    2016-03-01

    Photothermal medical laser treatments are extremely dependent on the generated tissue temperature. It is necessary to reach a certain temperature threshold to achieve successful results, whereas preventing to exceed an upper temperature value is required to avoid thermal damage. One method to overcome this problem is to use previously conducted dosimetry studies as a reference. Nevertheless, these results are acquired in controlled environments using uniform subjects. In the clinical environment, the optical and thermal characteristics (tissue color, composition and hydration level) vary dramatically among different patients. Therefore, the most reliable solution is to use a closed-loop feedback system that monitors the target tissue temperature to control laser exposure. In this study, we present a compact, non-contact temperature measurement system for the control of photothermal medical laser applications that is cost-efficient and simple to use. The temperature measurement is achieved using a focused, commercially available MOEMS infrared thermocouple sensor embedded in an off-axis arrangement on the laser beam delivery hand probe. The spot size of the temperature sensor is ca. 2.5 mm, reasonably smaller than the laser spot sizes used in photothermal medical laser applications. The temperature readout and laser control is realized using a microcontroller for fast operation. The utilization of the developed system may enable the adaptation of several medical laser treatments that are currently conducted only in controlled laboratory environments into the clinic. Laser tissue welding and cartilage reshaping are two of the techniques that are limited to laboratory research at the moment. This system will also ensure the safety and success of laser treatments aiming hyperthermia, coagulation and ablation, as well as LLLT and PDT.

  11. Deflecting light into resonant cavities for spectroscopy

    DOEpatents

    Zare, Richard N.; Martin, Juergen; Paldus, Barbara A.

    1998-01-01

    Light is coupled into a cavity ring down spectroscopy (CRDS) resonant cavity using an acousto-optic modulator. The AOM allows in-coupling efficiencies in excess of 40%, which is two to three orders of magnitude higher than in conventional systems using a cavity mirror for in-coupling. The AOM shutoff time is shorter than the roundtrip time of the cavity. The higher light intensities lead to a reduction in shot noise, and allow the use of relatively insensitive but fast-responding detectors such as photovoltaic detectors. Other deflection devices such as electro-optic modulators or elements used in conventional Q-switching may be used instead of the AOM. The method is particularly useful in the mid-infrared, far-infrared, and ultraviolet wavelength ranges, for which moderately reflecting input mirrors are not widely available.

  12. Deflecting light into resonant cavities for spectroscopy

    DOEpatents

    Zare, R.N.; Martin, J.; Paldus, B.A.

    1998-09-29

    Light is coupled into a cavity ring down spectroscopy (CRDS) resonant cavity using an acousto-optic modulator. The AOM allows in-coupling efficiencies in excess of 40%, which is two to three orders of magnitude higher than in conventional systems using a cavity mirror for in-coupling. The AOM shutoff time is shorter than the roundtrip time of the cavity. The higher light intensities lead to a reduction in shot noise, and allow the use of relatively insensitive but fast-responding detectors such as photovoltaic detectors. Other deflection devices such as electro-optic modulators or elements used in conventional Q-switching may be used instead of the AOM. The method is particularly useful in the mid-infrared, far-infrared, and ultraviolet wavelength ranges, for which moderately reflecting input mirrors are not widely available. 5 figs.

  13. Hundreds-fold Sensitivity Enhancement of Photothermal Microscopy in Near-Critical Xenon.

    PubMed

    Ding, Tina X; Hou, Lei; Meer, Harmen van der; Alivisatos, A Paul; Orrit, Michel

    2016-07-01

    Photothermal absorption microscopy of single Au nanoparticles was conducted at temperatures and pressures near the critical point of Xenon (Tc = 16.583 °C, Pc = 5.842 MPa). The divergence of the thermal expansion coefficient at the critical point makes the refractive index highly sensitive to changes in temperature, which directly translates to a large enhancement of the photothermal signal. We find that measurements taken near the critical point of Xe give a signal enhancement factor of up to 440 ± 130 over those taken in glycerol. The highest sensitivity recorded here corresponds to power dissipation of 64 pW, achieving a signal-to-noise ratio of 9.4 for 5 nm Au nanoparticles with an integration time of 50 ms, making this the most sensitive of any absorption microscopy technique reported to date. Enhancing the sensitivity of absorption microscopy lowers the operating heating power, allowing the technique to be more compatible with absorbers with absorption coefficient and photochemical stability lower than that of Au. PMID:27295542

  14. Band Excitation Kelvin probe force microscopy utilizing photothermal excitation

    DOE PAGESBeta

    Collins, Liam; Jesse, Stephen; Wisinger, Nina Balke; Rodriguez, Brian; Kalinin, Sergei; Li, Qian

    2015-01-01

    A multifrequency open loop Kelvin probe force microscopy (KPFM) approach utilizing photothermal as opposed to electrical excitation is developed. Photothermal band excitation (PthBE)-KPFM is implemented here in a grid mode on a model test sample comprising a metal-insulator junction with local charge-patterned regions. Unlike the previously described open loop BE-KPFM, which relies on capacitive actuation of the cantilever, photothermal actuation is shown to be highly sensitive to the electrostatic force gradient even at biases close to the contact potential difference (CPD). PthBE-KPFM is further shown to provide a more localized measurement of true CPD in comparison to the gold standardmore » ambient KPFM approach, amplitude modulated KPFM. Finally, PthBE-KPFM data contain information relating to local dielectric properties and electronic dissipation between tip and sample unattainable using conventional single frequency KPFM approaches.« less

  15. Injectable and responsively degradable hydrogel for personalized photothermal therapy.

    PubMed

    Wang, Changping; Wang, Xinyu; Dong, Kunyu; Luo, Jian; Zhang, Qiang; Cheng, Yiyun

    2016-10-01

    Near infrared-absorbing hydrogels are used for the repeated photothermal treatments of cancer. However, a long-term retention of hydrogel in the body leads to increased risk of toxicity. Here we developed an injectable and on-demand degradable hydrogel to conduct the repeated photothermal therapies (PTTs). Alginate-calcium hydrogel immobilized dendrimer-encapsulated platinum nanoparticles (DEPts) in its matrix represented excellent biocompatibility, and was degraded upon injecting chelates. Results from the in vivo studies reveal that the hydrogel/DEPts-mediated repeated PTTs suppressed tumor growth efficiently, and the hydrogel was degraded on-demand to allow renal secretion of DEPts out of the body. Furthermore, coating hydrogel/DEPts on the tumor instead of intratumoral injection could still ablate tumor efficiently. Our investigation provides a smart and safe hydrogel for photothermal cancer therapy. PMID:27449949

  16. Band excitation Kelvin probe force microscopy utilizing photothermal excitation

    NASA Astrophysics Data System (ADS)

    Collins, Liam; Jesse, Stephen; Balke, Nina; Rodriguez, Brian J.; Kalinin, Sergei; Li, Qian

    2015-03-01

    A multifrequency open loop Kelvin probe force microscopy (KPFM) approach utilizing photothermal as opposed to electrical excitation is developed. Photothermal band excitation (PthBE)-KPFM is implemented here in a grid mode on a model test sample comprising a metal-insulator junction with local charge-patterned regions. Unlike the previously described open loop BE-KPFM, which relies on capacitive actuation of the cantilever, photothermal actuation is shown to be highly sensitive to the electrostatic force gradient even at biases close to the contact potential difference (CPD). PthBE-KPFM is further shown to provide a more localized measurement of true CPD in comparison to the gold standard ambient KPFM approach, amplitude modulated KPFM. Finally, PthBE-KPFM data contain information relating to local dielectric properties and electronic dissipation between tip and sample unattainable using conventional single frequency KPFM approaches.

  17. Band excitation Kelvin probe force microscopy utilizing photothermal excitation

    SciTech Connect

    Collins, Liam E-mail: liq1@ORNL.gov; Rodriguez, Brian J.; Jesse, Stephen; Balke, Nina; Kalinin, Sergei; Li, Qian E-mail: liq1@ORNL.gov

    2015-03-09

    A multifrequency open loop Kelvin probe force microscopy (KPFM) approach utilizing photothermal as opposed to electrical excitation is developed. Photothermal band excitation (PthBE)-KPFM is implemented here in a grid mode on a model test sample comprising a metal-insulator junction with local charge-patterned regions. Unlike the previously described open loop BE-KPFM, which relies on capacitive actuation of the cantilever, photothermal actuation is shown to be highly sensitive to the electrostatic force gradient even at biases close to the contact potential difference (CPD). PthBE-KPFM is further shown to provide a more localized measurement of true CPD in comparison to the gold standard ambient KPFM approach, amplitude modulated KPFM. Finally, PthBE-KPFM data contain information relating to local dielectric properties and electronic dissipation between tip and sample unattainable using conventional single frequency KPFM approaches.

  18. Photothermal effects in ultra-precisely stabilized tunable microcavities.

    PubMed

    Brachmann, Johannes F S; Kaupp, Hanno; Hänsch, Theodor W; Hunger, David

    2016-09-01

    We study the mechanical stability of a tunable high-finesse microcavity under ambient conditions and investigate light-induced effects that can both suppress and excite mechanical fluctuations. As an enabling step, we demonstrate the ultra-precise electronic stabilization of a microcavity. We then show that photothermal mirror expansion can provide high-bandwidth feedback and improve cavity stability by almost two orders of magnitude. At high intracavity power, we observe self-oscillations of mechanical resonances of the cavity. We explain the observations by a dynamic photothermal instability, leading to parametric driving of mechanical motion. For an optimized combination of electronic and photothermal stabilization, we achieve a feedback bandwidth of 500 kHz and a noise level of 1.1 × 10-13 m rms. PMID:27607722

  19. Pulsed photothermal spectroscopy applied to lanthanide and actinide speciation

    SciTech Connect

    Berg, J.M.; Morris, D.E.; Clark, D.L.; Tait, C.D.; Woodruff, W.H. ); Ven Der Sluys, W.G. . Dept. of Chemistry)

    1991-01-01

    Several key elements important for the application of laser-based photothermal spectroscopies to the study of the complexation chemistry of lanthanides and actinides in solution have been demonstrated. The sensitivity of f-f electronic transition energies and band intensities to subtle changes in complexation was illustrated through comparison of visible and near infra-red absorption spectra of well-characterized U(IV) dimers with alkoxide ligands. Significant improvements in spectroscopic band resolution and energy measurement precision for solution species were shown to be achievable through work in frozen glasses at 77 K using a very simple cryogenic apparatus. A pulsed-laser photothermal spectroscopy apparatus was constructed and shown to be sensitive to optical density changes of 10{sup {minus}5} in an aqueous Nd{sup 3+} solution. In addition, the capability of obtaining photothermal lensing spectra of dilute actinide solutions in frozen glasses at 77 K was demonstrated. 6 refs., 5 figs.

  20. Current deflection NDE for pipeline inspection and monitoring

    NASA Astrophysics Data System (ADS)

    Jarvis, Rollo; Cawley, Peter; Nagy, Peter B.

    2016-02-01

    Failure of oil and gas pipelines can often be catastrophic, therefore routine inspection for time dependent degradation is essential. In-line inspection is the most common method used; however, this requires the insertion and retrieval of an inspection tool that is propelled by the fluid in the pipe and risks becoming stuck, so alternative methods must often be employed. This work investigates the applicability of a non-destructive evaluation technique for both the detection and growth monitoring of defects, particularly corrosion under insulation. This relies on injecting an electric current along the pipe and indirectly measuring the deflection of current around defects from perturbations in the orthogonal components of the induced magnetic flux density. An array of three orthogonally oriented anisotropic magnetoresistive sensors has been used to measure the magnetic flux density surrounding a 6'' schedule-40 steel pipe carrying 2 A quasi-DC axial current. A finite element model has been developed that predicts the perturbations in magnetic flux density caused by current deflection which has been validated by experimental results. Measurements of the magnetic flux density at 50 mm lift-off from the pipe surface are stable and repeatable to the order of 100 pT which suggests that defect detection or monitoring growth of corrosion-type defects may be possible with a feasible magnitude of injected current. Magnetic signals are additionally incurred by changes in the wall thickness of the pipe due to manufacturing tolerances, and material property variations. If a monitoring scheme using baseline subtraction is employed then the sensitivity to defects can be improved while avoiding false calls.

  1. Photothermal imaging through coherent infrared bundles

    NASA Astrophysics Data System (ADS)

    Milstein, Yonat; Tepper, Michal; Harrington, James A.; Ben David, Moshe; Gannot, Israel

    2011-03-01

    This study aims to develop a photothermal imaging system through a coherent infrared bundle. This system will be used to determine the oxygenation level of various tissues, suspected malignant tissues in particular. The oxygenation estimation is preformed using a computerized algorithm. In order to evaluate the system, different bundle configurations were used for the determination of the optimal one. Bundle transmittance and the algorithm's estimation ability were measured, measurements were performed using agar phantoms consisting of varying ratios of Methylene Blue and ICG. A bundle consisting of 19 Teflon waveguides with a of 1.1mm was found to be the optimal configuration with an RMS of the error of 9.38%. At a second stage the system was validated on blood samples with varying oxygenation levels and there oxygenation levels were estimated. This stage had an RMS of the error of 10.16% for the oxygenation level estimation for samples with a 50% oxygenation level and higher. Once the basic system was validated successfully on agar phantoms and blood samples a portable system was designed and built in order to fit the system for portable use. The portable system consists of a white light illuminating source followed by filters transmitting certain wavelengths, a transmitting fiber, a thermal imaging bundle and a portable thermal camera. This portable system will be evaluated in order to have an adequate portable system for implementing the method out of the lab.

  2. Waveguiding Actuators Based on Photothermally Responsive Hydrogels

    NASA Astrophysics Data System (ADS)

    Zhou, Ying; Hauser, Adam; Bende, Nakul; Kuzyk, Mark; Hayward, Ryan

    A simple means to achieve rapid and highly reversible photo-responsiveness in a hydrogel is to combine a thermally-responsive gel such as poly(N-isopropyl acrylamide) (PNIPAM), with the photothermal effect of gold nanoparticles. Relying on such composite gels, we fabricate micro-scale bilayer photoactuators by photolithographic patterning, and demonstrate their controlled bending/unbending behavior in response to visible light. In addition to actuation by flood exposure, 532 nm laser light can be waveguided through a plastic optical fiber to direct it into the photoactuator, providing the possibility for remotely controllable actuators that do not require line-of-sight access. The actuators show large magnitude responses within time-scales of ~1 s, consistent with the small dimensions of the actuators, but also exhibit smaller-scale responses over much longer times, suggesting the possibility of slow internal relaxations within the network. Based on our study on this bilayer system, we further explore fabrication methods for cylindrical actuators that are able to bend in arbitrary directions.

  3. Raman and photothermal spectroscopies for explosive detection

    NASA Astrophysics Data System (ADS)

    Finot, Eric; Brulé, Thibault; Rai, Padmnabh; Griffart, Aurélien; Bouhélier, Alexandre; Thundat, Thomas

    2013-06-01

    Detection of explosive residues using portable devices for locating landmine and terrorist weapons must sat- isfy the application criteria of high reproducibility, specificity, sensitivity and fast response time. Vibrational spectroscopies such as Raman and infrared spectroscopies have demonstrated their potential to distinguish the members of the chemical family of more than 30 explosive materials. The characteristic chemical fingerprints in the spectra of these explosives stem from the unique bond structure of each compound. However, these spectroscopies, developed in the early sixties, suffer from a poor sensitivity. On the contrary, MEMS-based chemical sensors have shown to have very high sensitivity lowering the detection limit down to less than 1 picogram, (namely 10 part per trillion) using sensor platforms based on microcantilevers, plasmonics, or surface acoustic waves. The minimum amount of molecules that can be detected depends actually on the transducer size. The selectivity in MEMS sensors is usually realized using chemical modification of the active surface. However, the lack of sufficiently selective receptors that can be immobilized on MEMS sensors remains one of the most critical issues. Microcantilever based sensors offer an excellent opportunity to combine both the infrared photothermal spectroscopy in their static mode and the unique mass sensitivity in their dynamic mode. Optical sensors based on localized plasmon resonance can also take up the challenge of addressing the selectivity by monitoring the Surface Enhanced Raman spectrum down to few molecules. The operating conditions of these promising localized spectroscopies will be discussed in terms of reliability, compactness, data analysis and potential for mass deployment.

  4. Electroactive Polymer Nanoparticles Exhibiting Photothermal Properties.

    PubMed

    Cantu, Travis; Rodier, Bradley; Iszard, Zachary; Kilian, Alissa; Pattani, Varun; Walsh, Kyle; Weber, Katharina; Tunnell, James; Betancourt, Tania; Irvin, Jennifer

    2016-01-01

    A method for the synthesis of electroactive polymers is demonstrated, starting with the synthesis of extended conjugation monomers using a three-step process that finishes with Negishi coupling. Negishi coupling is a cross-coupling process in which a chemical precursor is first lithiated, followed by transmetallation with ZnCl2. The resultant organozinc compound can be coupled to a dibrominated aromatic precursor to give the conjugated monomer. Polymer films can be prepared via electropolymerization of the monomer and characterized using cyclic voltammetry and ultraviolet-visible-near infrared (UV-Vis-NIR) spectroscopy. Nanoparticles (NPs) are prepared via emulsion polymerization of the monomer using a two-surfactant system to yield an aqueous dispersion of the polymer NPs. The NPs are characterized using dynamic light scattering, electron microscopy, and UV-Vis-NIR-spectroscopy. Cytocompatibility of NPs is investigated using the cell viability assay. Finally, the NP suspensions are irradiated with a NIR laser to determine their effectiveness as potential materials for photothermal therapy (PTT). PMID:26780244

  5. Salt-induced aggregation of gold nanoparticles for photoacoustic imaging and photothermal therapy of cancer.

    PubMed

    Sun, Mengmeng; Liu, Fei; Zhu, Yukun; Wang, Wansheng; Hu, Jin; Liu, Jing; Dai, Zhifei; Wang, Kun; Wei, Yen; Bai, Jing; Gao, Weiping

    2016-02-28

    The challenge in photothermal therapy (PTT) is to develop biocompatible photothermal transducers that can absorb and convert near-infrared (NIR) light into heat with high efficiency. Herein, we report salt-induced aggregation of gold nanoparticles (GNPs) in biological media to form highly efficient and biocompatible NIR photothermal transducers for PTT and photothermal/photoacoustic (PT/PA) imaging of cancer. The GNP depots in situ formed by salt-induced aggregation of GNPs show strong NIR absorption induced by plasmonic coupling between adjacent GNPs and very high photothermal conversion efficiency (52%), enabling photothermal destruction of tumor cells. More interestingly, GNPs in situ aggregate in tumors to form GNP depots, enabling simultaneous PT/PA imaging and PTT of the tumors. These findings may provide a simple and effective way to develop a new class of intelligent and biocompatible NIR photothermal transducers with high efficiency for PT/PA imaging and PTT. PMID:26847879

  6. Igniter adapter-to-igniter chamber deflection test

    NASA Technical Reports Server (NTRS)

    Cook, M.

    1990-01-01

    Testing was performed to determine the maximum RSRM igniter adapter-to-igniter chamber joint deflection at the crown of the inner joint primary seal. The deflection data was gathered to support igniter inner joint gasket resiliency predictions which led to launch commit criteria temperature determinations. The proximity (deflection) gage holes for the first test (Test No. 1) were incorrectly located; therefore, the test was declared a non-test. Prior to Test No. 2, test article configuration was modified with the correct proximity gage locations. Deflection data were successfully acquired during Test No. 2. However, the proximity gage deflection measurements were adversely affected by temperature increases. Deflections measured after the temperature rise at the proximity gages were considered unreliable. An analysis was performed to predict the maximum deflections based on the reliable data measured before the detectable temperature rise. Deflections to the primary seal crown location were adjusted to correspond to the time of maximum expected operating pressure (2,159 psi) to account for proximity gage bias, and to account for maximum attach and special bolt relaxation. The maximum joint deflection for the igniter inner joint at the crown of the primary seal, accounting for all significant correction factors, was 0.0031 in. (3.1 mil). Since the predicted (0.003 in.) and tested maximum deflection values were sufficiently close, the launch commit criteria was not changed as a result of this test. Data from this test should be used to determine if the igniter inner joint gasket seals are capable of maintaining sealing capability at a joint displacement of (1.4) x (0.0031 in.) = 0.00434 inches. Additional testing should be performed to increase the database on igniter deflections and address launch commit criteria temperatures.

  7. Photothermal single particle microscopy using a single laser beam

    SciTech Connect

    Selmke, Markus; Heber, André; Braun, Marco; Cichos, Frank

    2014-07-07

    We introduce a single-laser-beam photothermal microscopy scheme for the detection of single absorbing nano-objects. Here, a modulated incident laser beam with a constant intensity offset serves as pump and probe beam at the same time. Using the out-of-phase scattering response of the retarded thermorefractive wave field, the method provides a selective contrast for absorbers over a possible background of scatterers. The use of a single wavelength and a single beam, considerably simplifies the setup and integration of photothermal detection in existing microscopy schemes.

  8. Photothermal imaging of nanometer-sized metal particles among scatterers.

    PubMed

    Boyer, David; Tamarat, Philippe; Maali, Abdelhamid; Lounis, Brahim; Orrit, Michel

    2002-08-16

    Ambient optical detection of labeled molecules is limited for fluorescent dyes by photobleaching and for semiconducting nanoparticles by "blinking" effects. Because nanometer-sized metal particles do not optically bleach, they may be useful optical labels if suitable detection signals can be found. We demonstrate far-field optical detection of gold colloids down to diameters of 2.5 nanometers with a photothermal method that combines high-frequency modulation and polarization interference contrast. The photothermal image is immune to the effects of scattering background, which limits particle imaging through Rayleigh scattering to diameters larger than 40 nanometers. PMID:12183624

  9. Quantitative characterization of traumatic bruises by combined pulsed photothermal radiometry and diffuse reflectance spectroscopy

    NASA Astrophysics Data System (ADS)

    Vidovič, Luka; Milanič, Matija; Randeberg, Lise L.; Majaron, Boris

    2015-02-01

    We apply diffuse reflectance spectroscopy (DRS) and pulsed photothermal radiometry (PPTR) for characterization of the bruise evolution process. While DRS provides information in a wide range of visible wavelengths, the PPTR enables extraction of detailed depth distribution and concentration profiles of selected absorbers (e.g. melanin, hemoglobin). In this study, we simulate experimental DRS spectra and PPTR signals using the Monte Carlo technique and focus on characterization of a suitable fitting approach for their analysis. We find inverse Monte Carlo to be superior to the diffusion approximation approach for the inverse analysis of DRS spectra. The analysis is then augmented with information obtainable by the fitting of the PPTR signal. We show that both techniques can be coupled in a combined fitting approach. The combining of two complementary techniques improves the robustness and accuracy of the inverse analysis, enabling a comprehensive quantitative characterization of the bruise evolution dynamics.

  10. Teach Deflection Concepts with Hacksaw Blades and Rubber Bands

    ERIC Educational Resources Information Center

    Roman, Harry T.

    2013-01-01

    Technology and engineering educators can use a simple hacksaw blade to help students learn about deflection, as that which occurs in a beam. Here the beam is fixed at one end and allowed to deflect in a manner that is easy to see and measure--the hacksaw blade represents a cantilever, an overhanging structure. This simple and very inexpensive…

  11. A complete analysis of the laser beam deflection systems used in cantilever-based systems.

    PubMed

    Beaulieu, L Y; Godin, Michel; Laroche, Olivier; Tabard-Cossa, Vincent; Grütter, Peter

    2007-01-01

    A working model has been developed which can be used to significantly increase the accuracy of cantilever deflection measurements using optical beam techniques (used in cantilever-based sensors and atomic force microscopes), while simultaneously simplifying their use. By using elementary geometric optics and standard vector analysis it is possible, without any fitted or adjustable parameters, to completely and accurately describe the relationship between the cantilever deflection and the signal measured by a position sensitive photo-detector. By arranging the geometry of the cantilever/optical beam, it is possible to tailor the detection system to make it more sensitive at different stages of the cantilever deflection or to simply linearize the relationship between the cantilever deflection and the measured detector signal. Supporting material and software has been made available for download at http://www.physics.mun.ca/beauliu_lab/papers/cantilever_analysis.htm so that the reader may take full advantage of the model presented herein with minimal effort. PMID:17174033

  12. Applicability of moire deflection tomography for diagnosing arc plasmas

    SciTech Connect

    Chen Yunyun; Song Yang; He Anzhi; Li Zhenhua

    2009-01-20

    The argon arc plasma whose central temperature, 1.90x10{sup 4} K, is used as a practical example for an experiment to research the applicability of moire deflection tomography in arc plasma flow-field diagnosis. The experimental result indicates that moire deflection of the measured argon arc plasma is very small, even smaller than that of a common flame with the maximal temperature of nearly 1.80x10{sup 3} K. The refractive-index gradient in moire deflection tomography mainly contributes to the temperature gradient in essence when the probe wavelength and pressure are certain in plasma diagnosis. The applicable temperature ranges of moire deflection tomography in the argon arc plasma diagnosis are given with the probe wavelength 532 nm at 1 atm in certain measuring error requirements. In a word, the applicable temperature range of moire deflection tomography for arc plasma diagnosis is intimately related to the probe wavelength and the practical measuring requirements.

  13. A computational study of asymmetric glottal jet deflection during phonation.

    PubMed

    Zheng, X; Mittal, R; Bielamowicz, S

    2011-04-01

    Two-dimensional numerical simulations are used to explore the mechanism for asymmetric deflection of the glottal jet during phonation. The model employs the full Navier-Stokes equations for the flow but a simple laryngeal geometry and vocal-fold motion. The study focuses on the effect of Reynolds number and glottal opening angle with a particular emphasis on examining the importance of the so-called "Coanda effect" in jet deflection. The study indicates that the glottal opening angle has no substantial effect on glottal jet deflection. Deflection in the glottal jet is always preceded by large-scale asymmetry in the downstream portion of the glottal jet. A detailed analysis of the velocity and vorticity fields shows that these downstream asymmetric vortex structures induce a flow at the glottal exit which is the primary driver for glottal jet deflection. PMID:21476669

  14. Nonlinear large-deflection analysis of orthodontic wires.

    PubMed

    Hayashi, Kazuo; Araki, Yoshima; Mizoguchi, Itaru

    2004-02-01

    The purposes of this study were (1) to measure the nonlinear force-deflection behavior of selected orthodontic wires using a conventional tensile test, (2) to extend a mathematical model for simulating the force system produced by orthodontic wires based on the small-deflection linear theory to the large-deflection nonlinear theory, and (3) to examine the effects of the cross-section and mechanical properties of orthodontic wires on nonlinear characteristics. A method for extending a mathematical model for simulating the force system produced by orthodontic wires based on the small-deflection linear theory to the large-deflection nonlinear theory was established, and this can provide a clear view of the true nature of orthodontic wires. Furthermore, our results demonstrated that the nonlinear properties of orthodontic wires were affected more by the cross-sectional shape than by mechanical properties. PMID:15038499

  15. A computational study of asymmetric glottal jet deflection during phonation

    PubMed Central

    Zheng, X.; Mittal, R.; Bielamowicz, S.

    2011-01-01

    Two-dimensional numerical simulations are used to explore the mechanism for asymmetric deflection of the glottal jet during phonation. The model employs the full Navier–Stokes equations for the flow but a simple laryngeal geometry and vocal-fold motion. The study focuses on the effect of Reynolds number and glottal opening angle with a particular emphasis on examining the importance of the so-called “Coanda effect” in jet deflection. The study indicates that the glottal opening angle has no substantial effect on glottal jet deflection. Deflection in the glottal jet is always preceded by large-scale asymmetry in the downstream portion of the glottal jet. A detailed analysis of the velocity and vorticity fields shows that these downstream asymmetric vortex structures induce a flow at the glottal exit which is the primary driver for glottal jet deflection. PMID:21476669

  16. Intelligent deflection routing in buffer-less networks.

    PubMed

    Haeri, Soroush; Trajković, Ljiljana

    2015-02-01

    Deflection routing is employed to ameliorate packet loss caused by contention in buffer-less architectures such as optical burst-switched networks. The main goal of deflection routing is to successfully deflect a packet based only on a limited knowledge that network nodes possess about their environment. In this paper, we present a framework that introduces intelligence to deflection routing (iDef). iDef decouples the design of the signaling infrastructure from the underlying learning algorithm. It consists of a signaling and a decision-making module. Signaling module implements a feedback management protocol while the decision-making module implements a reinforcement learning algorithm. We also propose several learning-based deflection routing protocols, implement them in iDef using the ns-3 network simulator, and compare their performance. PMID:25532199

  17. Photothermal Therapy: Metabolizable Ultrathin Bi2 Se3 Nanosheets in Imaging-Guided Photothermal Therapy (Small 30/2016).

    PubMed

    Xie, Hanhan; Li, Zhibin; Sun, Zhengbo; Shao, Jundong; Yu, Xue-Feng; Guo, Zhinan; Wang, Jiahong; Xiao, Quanlan; Wang, Huaiyu; Wang, Qu-Quan; Zhang, Han; Chu, Paul K

    2016-08-01

    Ultrathin Bi2 Se3 nanosheets are prepared by a solution method. As described on page 4136 by X.-F. Yu, Q.-Q. Wang, P. K. Chu, and co-workers, such ultrathin Bi2 Se3 nanosheets exhibit strong near infrared (NIR) light absorption, excellent photothermal and photoacoustic performance, enabling efficient imaging-guided photothermal therapy. Furthermore, these Bi2 Se3 nanosheets are well metabolized. These attractive properties render the Bi2 Se3 nanosheets promising as a NIR-triggered theranostic agents in cancer therapies. PMID:27492498

  18. AIDA: the Asteroid Impact & Deflection Assessment mission

    NASA Astrophysics Data System (ADS)

    Vincent, Jean-Baptiste

    2016-07-01

    The Asteroid Impact & Deflection Assessment (AIDA) mission is a joint cooperation between European and US space agencies that consists of two separate and independent spacecraft that will be launched to a binary asteroid system, the near-Earth asteroid Didymos, to assess the possibility of deflecting an asteroid trajectory by using a kinetic impactor. The European Asteroid Impact Mission (AIM) is under Phase A/B1 study at ESA from March 2015 until summer 2016. AIM is set to rendez-vous with the asteroid system a few months prior to the impact by the US Double Asteroid Redirection Test (DART) spacecraft to fully characterize the smaller of the two binary components. AIM is a unique mission as it will be the first time that a spacecraft will investigate the surface, subsurface, and internal properties of a small binary near Earth asteroid. In addition it will perform various important technology demonstrations that can serve other space missions: AIM will release a set of CubeSats in deep space and a lander on the surface of the smaller asteroid and for the first time, deep-space inter-satellite linking will be demonstrated between the main spacecraft, the CubeSats, and the lander, and data will also be transmitted from interplanetary space to Earth by a laser communication system. The knowledge obtained by this mission will have great implications for our understanding of the history of the Solar System. Small asteroids are believed to result from collisions and other processes (e.g., spinup, shaking) that made them what they are now. Having direct information on their surface and internal properties will allow us to understand how these processes work and transform these small bodies as well as, for this particular case, how a binary system forms. So far, our understanding of the collisional process and the validation of numerical simulations of the impact process rely on impact experiments at laboratory scales. With DART, thanks to the characterization of the

  19. Pulsed photothermal depth profiling of tattoos undergoing laser removal treatment

    NASA Astrophysics Data System (ADS)

    Milanic, Matija; Majaron, Boris

    2012-02-01

    Pulsed photothermal radiometry (PPTR) allows noninvasive determination of temperature depth profiles induced by pulsed laser irradiation of strongly scattering biological tissues and organs, including human skin. In present study, we evaluate the potential of this technique for investigational characterization and possibly quantitative evaluation of laser tattoo removal. The study involved 5 healthy volunteers (3 males, 2 females), age 20-30 years, undergoing tattoo removal treatment using a Q-switched Nd:YAG laser. There were four measurement and treatment sessions in total, separated by 2-3 months. Prior to each treatment, PPTR measurements were performed on several tattoo sites and one nearby healthy site in each patient, using a 5 ms Nd:YAG laser at low radiant exposure values and a dedicated radiometric setup. The laser-induced temperature profiles were then reconstructed by applying a custom numerical code. In addition, each tatoo site was documented with a digital camera and measured with a custom colorimetric system (in tristimulus color space), providing an objective evaluation of the therapeutic efficacy to be correlated with our PPTR results. The results show that the laser-induced temperature profile in untreated tattoos is invariably located at a subsurface depth of 300 μm. In tattoo sites that responded well to laser therapy, a significant drop of the temperature peak was observed in the profiles obtained from PPTR record. In several sites that appeared less responsive, as evidenced by colorimetric data, a progressive shift of the temperature profile deeper into the dermis was observed over the course of consecutive laser treatments, indicating that the laser tattoo removal was efficient.

  20. Load Deflection Characteristics of Nickel Titanium Initial Archwires

    PubMed Central

    Aghili, Hossein; Yasssaei, Sogra; Ahmadabadi, Mahmoud Nilli

    2015-01-01

    Objectives: The aim of this study was to assess and compare the characteristics of commonly used initial archwires by their load deflection graphs. Materials and Methods: This study tested three wire designs namely copper nickel titanium (CNT), nickel titanium (NiTi), and multi-strand NiTi (MSNT) archwires engaged in passive self-ligating (PSL) brackets, active self-ligating (ASL) brackets or conventional brackets. To evaluate the mechanical characteristics of the specimens, a three-point bending test was performed. The testing machine vertically applied force on the midpoint of the wire between the central incisor and canine teeth to obtain 2 and 4mm of deflection. The force level at maximum deflection and characteristics of plateau (the average plateau load and the plateau length) were recorded. Two-way ANOVA and Tukey’s test were used at P <0.05 level of significance. Results: Force level at maximum deflection and plateau length were significantly affected by the amount of deflection. The type of archwires and brackets had significant effects on force level at maximum deflection, and plateau length. However, the bracket type had no significant effect on the average plateau force. Conclusion: With any type of brackets in deflections of 2 and 4mm, MSNT wire exerted the lowest while NiTi wire exerted the highest force level at maximum deflection and plateau phase. The force level at maximum deflection and the plateau length increased with raising the amount of primary deflection; however the average plateau force did not change significantly. PMID:27148381

  1. Mission Designs for Demonstrating Gravity Tractor Asteroid Deflection

    NASA Astrophysics Data System (ADS)

    Busch, M.; Faber, N.; Eggl, S.; Morrison, D.; Clark, A.; Frost, C.; Jaroux, B. A.; Khetawat, V.

    2015-12-01

    Gravity tractor asteroid deflection relies on the gravitational attraction between the target and a nearby spacecraft; using low-thrust propulsion to change the target's trajectory slowly but continuously. Our team, based at the NASA Ames Mission Design Center, prepared designs for a Gravity Tractor Demonstration Mission (GTDM) for the European Commission's NEOShield initiative. We found five asteroids with well-known orbits and opportunities for efficient stand-alone demonstrations in the 2020s. We selected one object, 2000 FJ10, for a detailed design analysis. Our GTDM design has a 4 kW solar-electric propulsion system and launch mass of 1150 kg. For a nominal asteroid mass of 3 x 109 kg and diameter 150 m, and a hovering altitude 125 m above the asteroid's surface, GTDM would change FJ10's semi-major axis by 10 km over 2 years. To measure the deflection clearly and to permit safe hovering by the spacecraft, several months of survey and characterization are required prior to the active tractoring phase of the mission. Accurate tracking is also required after the tractoring phase, to ensure that the asteroid has indeed been deflected as intended. The GTDM design includes both spacecraft and Earth-based observations of FJ10 to verify the deflection. The estimated cost of GTDM is $280 million. Trajectory analysis for GTDM confirmed that the outcome of a deflection of any asteroid depends on when that deflection is performed. Compared to kinetic impactor deflection, the gradual deflection from a gravity tractor produces comparable results for a given total momentum transfer. However, a gravity tractor can have greater flexibility in the direction in which the target asteroid can be deflected. Asteroid deflection scenarios must be modeled carefully on a case-to-case basis. We will review implications of the results of the GTDM study to other proposed gravity tractor demonstrations, such as that included in NASA's Asteroid Redirect Mission.

  2. Annealing polymer nanofibrous nanocomposite mats via photothermal heating: effects on overall crystallinity, morphology, and mechanical properties

    NASA Astrophysics Data System (ADS)

    Gorga, Russell; Clarke, Laura; Bochinski, Jason; Viswanath, Vidya; Maity, Somsubhra

    2014-03-01

    Metal nanoparticles embedded within polymeric systems can be made to act as localized heat sources thereby aiding in-situ polymer processing. This is made possible by the surface plasmon resonance mediated photothermal effect of metal nanoparticles, wherein incident light absorbed by the nanoparticle generates a non-equilibrium electron distribution which subsequently transfers this energy into the surrounding medium, resulting in a temperature increase in the immediate region around the particle. Here we demonstrate this effect in polyethylene oxide-gold nanoparticle electrospun nanofibrous mats, which have been annealed at temperatures above the glass transition. A non-contact temperature measurement technique utilizing embedded fluorophores (perylene) has been used to monitor the average temperature within samples. The effect of annealing methods (conventional and photothermal) and annealing conditions (temperature and time) on the fiber morphology, overall crystallinity, and mechanical properties is discussed. In conclusion we demonstrate that the specificity of plasmonic heating coupled with the inside-outside approach of annealing presents a unique tool to improve crystallinity, and therefore mechanical properties, of the polymer mats while maintaining the unique nanofibrous morphologies. Supported by the National Science Foundation (CMMI-1069108).

  3. Engineering on-chip nanoporous gold material libraries via precision photothermal treatment.

    PubMed

    Chapman, Christopher A R; Wang, Ling; Biener, Juergen; Seker, Erkin; Biener, Monika M; Matthews, Manyalibo J

    2016-01-14

    Libraries of nanostructured materials on a single chip are a promising platform for high throughput and combinatorial studies of structure-property relationships in the fields of physics and biology. Nanoporous gold (np-Au), produced by an alloy corrosion process, is a nanostructured material specifically suited for such studies because of its self-similar thermally induced coarsening behavior. However, traditional heat application techniques for the modification of np-Au are bulk processes that cannot be used to generate a library of different pore sizes on a single chip. Here, laser micro-processing offers an attractive solution to this problem by providing a means to apply energy with high spatial and temporal resolution. In the present study we use finite element multiphysics simulations to predict the effects of laser mode (continuous-wave vs. pulsed) and thermal conductivity of the supporting substrate on the local np-Au film temperatures during photothermal annealing. Based on these results we discuss the mechanisms by which the np-Au network is coarsened. Thermal transport simulations predict that continuous-wave mode laser irradiation of np-Au thin films on a silicon substrate supports the widest range of morphologies that can be created through photothermal annealing of np-Au. Using the guidance provided by simulations, we successfully fabricate an on-chip material library consisting of 81 np-Au samples of 9 different morphologies for use in the parallel study of structure-property relationships. PMID:26411758

  4. Measurements of the thermal diffusivity tensor of polymer-carbon fiber composites by photothermal methods

    SciTech Connect

    Salazar, A.; Sanchez-Lavega, A.

    1998-03-01

    The thermal diffusivity tensor of a polymer-carbon fiber composite with unidirectionally distributed fibers has been measured using a modulated photothermal mirage device. The thermal diffusivity along the fibers is k{sub {parallel}} = 6.0 {+-} 0.5 mm{sup 2}{center_dot}s{sup {minus}1}, that perpendicular to the fibers is k{sub {perpendicular}} = 0.35 {+-} 0.05 mm{sup 2}{center_dot}s{sup {minus}1}, and that perpendicular to the sample surface is k{sub z} = 0.40 {+-} 0.15 mm{sup 2}{center_dot}s{sup {minus}1}. These results have been confirmed by independent measurements on the sample by other laboratories using three other different photothermal techniques. A previous claim on anomalous results found on this sample (k{sub {parallel}} < k{sub {perpendicular}} and high thermal diffusivities) can be explained by the inappropriate use of the frequency range. The authors have also found that there is not perfect thermal contact between the fibers and the matrix, which can be characterized by the thermal contact resistance of R{sub th} = (9 {+-} 2) {times} 10{sup {minus}6} m{sup 2}{center_dot}K{center_dot}W{sup {minus}1}.

  5. Complex genetic, photothermal, and photoacoustic analysis of nanoparticle-plant interactions

    PubMed Central

    Khodakovskaya, Mariya V.; de Silva, Kanishka; Nedosekin, Dmitry A.; Dervishi, Enkeleda; Biris, Alexandru S.; Shashkov, Evgeny V.; Galanzha, Ekaterina I.; Zharov, Vladimir P.

    2011-01-01

    Understanding the nature of interactions between engineered nanomaterials and plants is crucial in comprehending the impact of nanotechnology on the environment and agriculture with a focus on toxicity concerns, plant disease treatment, and genetic engineering. To date, little progress has been made in studying nanoparticle-plant interactions at single nanoparticle and genetic levels. Here, we introduce an advanced platform integrating genetic, Raman, photothermal, and photoacoustic methods. Using this approach, we discovered that multiwall carbon nanotubes induce previously unknown changes in gene expression in tomato leaves and roots, particularly, up-regulation of the stress-related genes, including those induced by pathogens and the water-channel LeAqp2 gene. A nano-bubble amplified photothermal/photoacoustic imaging, spectroscopy, and burning technique demonstrated the detection of multiwall carbon nanotubes in roots, leaves, and fruits down to the single nanoparticle and cell level. Thus, our integrated platform allows the study of nanoparticles’ impact on plants with higher sensitivity and specificity, compared to existing assays. PMID:21189303

  6. Photothermal heating as a methodology for post processing of polymeric nanofibers

    NASA Astrophysics Data System (ADS)

    Gorga, Russell; Clarke, Laura; Bochinski, Jason; Viswanath, Vidya; Maity, Somsubhra; Dong, Ju; Firestone, Gabriel

    2015-03-01

    Metal nanoparticles embedded within polymeric systems can be made to act as localized heat sources thereby aiding in-situ polymer processing. This is made possible by the surface plasmon resonance (SPR) mediated photothermal effect of metal (in this case gold) nanoparticles, wherein incident light absorbed by the nanoparticle generates a non-equilibrium electron distribution which subsequently transfers this energy into the surrounding medium, resulting in a temperature increase in the immediate region around the particle. Here we demonstrate this effect in polymer nanocomposite systems, specifically electrospun polyethylene oxide nanofibrous mats, which have been annealed at temperatures above the glass transition. A non-contact temperature measurement technique utilizing embedded fluorophores (perylene) has been used to monitor the average temperature within samples. The effect of annealing methods (conventional and photothermal) and annealing conditions (temperature and time) on the fiber morphology, overall crystallinity, and mechanical properties is discussed. This methodology is further utilized in core-sheath nanofibers to crosslink the core material, which is a pre-cured epoxy thermoset. NSF Grant CMMI-1069108.

  7. Photothermally induced bromination of carbon/polymer bipolar plate materials for fuel cell applications

    NASA Astrophysics Data System (ADS)

    Schade, Martin; Franzka, Steffen; Cappuccio, Franco; Peinecke, Volker; Heinzel, Angelika; Hartmann, Nils

    2015-05-01

    A facile photothermal procedure for direct functionalization of carbon/polymer bipolar plate materials is demonstrated. Through irradiation with a microfocused beam of an Ar+-laser at λ = 514 nm in gaseous bromine and distinct laser powers and pulse lengths local bromination of the carbon/polymer material takes place. At a 1/e spot diameter of 2.1 μm, functionalized surface areas with diameters down to 5 μm are fabricated. In complementary experiments large-area bromination is investigated using an ordinary tungsten lamp. For characterization contact angle goniometry, X-ray photoelectron spectroscopy and electron microscopy in conjunction with labeling techniques are employed. After irradiation bromine groups can easily be substituted by other chemical functionalities, e.g. azide and amine groups. This provides a facile approach in order to fabricate surface patterns and gradient structures with varying wetting characteristics. Mechanistic aspects and prospects of photothermal routines in micropatterning of carbon/polymer materials are discussed.

  8. Long-term deflections of reinforced concrete elements: accuracy analysis of predictions by different methods

    NASA Astrophysics Data System (ADS)

    Gribniak, Viktor; Bacinskas, Darius; Kacianauskas, Rimantas; Kaklauskas, Gintaris; Torres, Lluis

    2013-08-01

    Long-term deflection response of reinforced concrete flexural members is influenced by the interaction of complex physical phenomena, such as concrete creep, shrinkage and cracking, which makes their prediction difficult. A number of approaches are proposed by design codes with different degrees of simplification and accuracy. This paper statistically investigates accuracy of long-term deflection predictions made by some of the most widely used design codes ( Eurocode 2, ACI 318, ACI 435, and the new Russian code SP 52-101) and a numerical technique proposed by the authors. The accuracy is analyzed using test data of 322 reinforced concrete members from 27 test programs reported in the literature. The predictions of each technique are discussed, and a comparative analysis is made showing the influence of different parameters, such as sustained loading duration, compressive strength of concrete, loading intensity and reinforcement ratio, on the prediction accuracy.

  9. Salt-induced aggregation of gold nanoparticles for photoacoustic imaging and photothermal therapy of cancer

    NASA Astrophysics Data System (ADS)

    Sun, Mengmeng; Liu, Fei; Zhu, Yukun; Wang, Wansheng; Hu, Jin; Liu, Jing; Dai, Zhifei; Wang, Kun; Wei, Yen; Bai, Jing; Gao, Weiping

    2016-02-01

    The challenge in photothermal therapy (PTT) is to develop biocompatible photothermal transducers that can absorb and convert near-infrared (NIR) light into heat with high efficiency. Herein, we report salt-induced aggregation of gold nanoparticles (GNPs) in biological media to form highly efficient and biocompatible NIR photothermal transducers for PTT and photothermal/photoacoustic (PT/PA) imaging of cancer. The GNP depots in situ formed by salt-induced aggregation of GNPs show strong NIR absorption induced by plasmonic coupling between adjacent GNPs and very high photothermal conversion efficiency (52%), enabling photothermal destruction of tumor cells. More interestingly, GNPs in situ aggregate in tumors to form GNP depots, enabling simultaneous PT/PA imaging and PTT of the tumors. These findings may provide a simple and effective way to develop a new class of intelligent and biocompatible NIR photothermal transducers with high efficiency for PT/PA imaging and PTT.The challenge in photothermal therapy (PTT) is to develop biocompatible photothermal transducers that can absorb and convert near-infrared (NIR) light into heat with high efficiency. Herein, we report salt-induced aggregation of gold nanoparticles (GNPs) in biological media to form highly efficient and biocompatible NIR photothermal transducers for PTT and photothermal/photoacoustic (PT/PA) imaging of cancer. The GNP depots in situ formed by salt-induced aggregation of GNPs show strong NIR absorption induced by plasmonic coupling between adjacent GNPs and very high photothermal conversion efficiency (52%), enabling photothermal destruction of tumor cells. More interestingly, GNPs in situ aggregate in tumors to form GNP depots, enabling simultaneous PT/PA imaging and PTT of the tumors. These findings may provide a simple and effective way to develop a new class of intelligent and biocompatible NIR photothermal transducers with high efficiency for PT/PA imaging and PTT. Electronic supplementary

  10. Photoacoustic and Photothermal Effects in Particulate Suspensions

    SciTech Connect

    Diebold, Gerald, J.

    2009-04-30

    A summary of the research areas investigated by the author during the grant period is given. Experiments and theory have been carried out on the photoacoustic effect arising from a number of physical and chemical processes. A number of studies of the photoacoustic effect as it occurs in transient grating experiments have been completed. The research done with the Ludwig-Soret effect on the generation of shock waves is reported. Other research, such as that carried out on interferometric and beam deflection microphones, the use of microphones in vacuum as momentum flux detectors, and chemical generation of sonoluminescence is listed. A list of published research including selected publications, a complete list of journal articles, books, review articles, and reviews are given.

  11. Flower-like PEGylated MoS2 nanoflakes for near-infrared photothermal cancer therapy

    PubMed Central

    Feng, Wei; Chen, Liang; Qin, Ming; Zhou, Xiaojun; Zhang, Qianqian; Miao, Yingke; Qiu, Kexin; Zhang, Yanzhong; He, Chuanglong

    2015-01-01

    Photothermal cancer therapy has attracted considerable interest for cancer treatment in recent years, but the effective photothermal agents remain to be explored before this strategy can be applied clinically. In this study, we therefore develop flower-like molybdenum disulfide (MoS2) nanoflakes and investigate their potential for photothermal ablation of cancer cells. MoS2 nanoflakes are synthesized via a facile hydrothermal method and then modified with lipoic acid-terminated polyethylene glycol (LA-PEG), endowing the obtained nanoflakes with high colloidal stability and very low cytotoxicity. Upon irradiation with near infrared (NIR) laser at 808 nm, the nanoflakes showed powerful ability of inducing higher temperature, good photothermal stability and high photothermal conversion efficiency. The in vitro photothermal effects of MoS2-PEG nanoflakes with different concentrations were also evaluated under various power densities of NIR 808-nm laser irradiation, and the results indicated that an effective photothermal killing of cancer cells could be achieved by a low concentration of nanoflakes under a low power NIR 808-nm laser irradiation. Furthermore, cancer cell in vivo could be efficiently destroyed via the photothermal effect of MoS2-PEG nanoflakes under the irradiation. These results thus suggest that the MoS2-PEG nanoflakes would be as promising photothermal agents for future photothermal cancer therapy. PMID:26632249

  12. Flower-like PEGylated MoS2 nanoflakes for near-infrared photothermal cancer therapy

    NASA Astrophysics Data System (ADS)

    Feng, Wei; Chen, Liang; Qin, Ming; Zhou, Xiaojun; Zhang, Qianqian; Miao, Yingke; Qiu, Kexin; Zhang, Yanzhong; He, Chuanglong

    2015-12-01

    Photothermal cancer therapy has attracted considerable interest for cancer treatment in recent years, but the effective photothermal agents remain to be explored before this strategy can be applied clinically. In this study, we therefore develop flower-like molybdenum disulfide (MoS2) nanoflakes and investigate their potential for photothermal ablation of cancer cells. MoS2 nanoflakes are synthesized via a facile hydrothermal method and then modified with lipoic acid-terminated polyethylene glycol (LA-PEG), endowing the obtained nanoflakes with high colloidal stability and very low cytotoxicity. Upon irradiation with near infrared (NIR) laser at 808 nm, the nanoflakes showed powerful ability of inducing higher temperature, good photothermal stability and high photothermal conversion efficiency. The in vitro photothermal effects of MoS2-PEG nanoflakes with different concentrations were also evaluated under various power densities of NIR 808-nm laser irradiation, and the results indicated that an effective photothermal killing of cancer cells could be achieved by a low concentration of nanoflakes under a low power NIR 808-nm laser irradiation. Furthermore, cancer cell in vivo could be efficiently destroyed via the photothermal effect of MoS2-PEG nanoflakes under the irradiation. These results thus suggest that the MoS2-PEG nanoflakes would be as promising photothermal agents for future photothermal cancer therapy.

  13. Throat Flow Modelling of Expansion Deflection Nozzles

    NASA Astrophysics Data System (ADS)

    Taylor, N. V.; Hempsell, C. M.

    Modelling of the supersonic flow within a rocket nozzle of both conventional and expansion deflection (ED) design is well handled by Method of Characteristics based algorithms. This approach provides both a predic- tion of the flowfield, and allows efficient optimisation of nozzle shape with respect to length. However, the Method of Characteristics requires a solution of the transonic flow through the nozzle throat to provide initial conditions, and the accuracy of the description of the transonic flow will clearly affect the overall accuracy of the complete nozzle flow calculation. However, it is relatively simple to show that conventional analytical methods for this process break down when applied to the more complex throat geometry of ED nozzles. This requires the use of a time marching solution method, which allows the analysis of the flow within this region even on such advanced configurations. This paper demonstrates this capability, outlines a general method for ED nozzle throat geometric definition, and examines the effect of various throat parameters on the permissible range of ED contours. It is found that the design of length optimised ED nozzles is highly sensitive to small changes in these parameters, and hence they must be selected with care.

  14. Photothermal response of near-infrared-absorbing NanoGUMBOS.

    PubMed

    Dumke, Jonathan C; Qureshi, Ammar; Hamdan, Suzana; El-Zahab, Bilal; Das, Susmita; Hayes, Daniel J; Boldor, Dorin; Rupnik, Kresimir; Warner, Isiah M

    2014-01-01

    The photothermal properties of several near-infrared-absorbing nanoparticles derived from group of uniform materials based on organic salts (GUMBOS) and composed of cationic dyes coupled with biocompatible anions are evaluated. These nanoparticles were synthesized using a reprecipitation method performed at various pH values: 2.0, 5.0, 7.0, 9.0, and 11.0. The cations for the nanoparticles derived from GUMBOS (nanoGUMBOS), [1048] and [1061], have absorbance maxima at wavelengths overlapping with human soft tissue absorbance minima. Near-infrared-absorbing nanoGUMBOS excited with a 1064 nm continuous laser led to heat generation, with an average temperature increase of 20.4 ± 2.7 °C. Although the [1061][Deoxycholate] nanoGUMBOS generated the highest temperature increase (23.7 ± 2.4 °C), it was the least photothermally efficient compound (13.0%) due to its relatively large energy band gap of 0.892 eV. The more photothermally efficient compound [1048][Ascorbate] (64.4%) had a smaller energy band gap of 0.861 eV and provided an average photothermal temperature increase of 21.0 ± 2.1 °C. PMID:24666951

  15. Distinguishing the Photothermal and Photoinjection Effects in Vanadium Dioxide Nanowires

    NASA Astrophysics Data System (ADS)

    Wang, Xi; Gao, Hanwei

    Vanadium dioxide (VO2) has drawn significant attention for its unique metal-to-insulator transition. The high electrical resistivity below the transition temperature is a result of the strong electron correlation with the assistance of lattice distortion. Theoretical calculations indicated that the strong inter-electron interactions might induce intriguing optoelectronic phenomena, such as the multiple exciton generation. However, the resistivity of VO2 is temperature sensitive. Therefore, the light-induced conductivity in VO2 has often been attributed to the photothermal effects. In this work, we distinguished the photothermal and photoinjection effects in VO2 nanowires by varying the chopping frequency of the optical illumination. In our VO2 nanowires, the relatively slow photothermal processes can be well suppressed when the chopping frequency >2 kHz, whereas the fast photoinjection component (direct photo-excitation of charge carriers) remains constant at all chopping frequencies. By separating the photothermal and photoinjection processes, our work set the basis for further studies of carrier dynamics under optical excitations in strongly correlated materials. This work is supported by the Start-Up Funds and the First-Year Assistant Professor Award from the Florida State University.

  16. Advances in cancer research using gold nanoparticles mediated photothermal ablation

    PubMed Central

    MOCAN, LUCIAN; MATEA, CRISTIAN T.; BARTOS, DANA; MOSTEANU, OFELIA; POP, TEODORA; MOCAN, TEODORA; IANCU, CORNEL

    2016-01-01

    Recent research suggests that nanotechnologies may lead to the development of novel cancer treatment. Gold nanoparticles with their unique physical and chemical properties hold great hopes for the development of thermal-based therapies against human malignancies. This review will focus on various strategies that have been developed to use gold nanoparticles as photothermal agents against human cancers. PMID:27152068

  17. Laser photothermal spectroscopy of light-induced absorption

    SciTech Connect

    Skvortsov, L A

    2013-01-31

    Basic methods of laser photothermal spectroscopy, which are used to study photoinduced absorption in various media, are briefly considered. Comparative analysis of these methods is performed and the latest results obtained in this field are discussed. Different schemes and examples of their practical implementation are considered. (review)

  18. Longitudinal Bunch Shape Diagnostics With Coherent Radiation And a Transverse Deflecting Cavity at TTF2

    SciTech Connect

    Grimm, O.; Frohlich, L.; Klose, K.; Nagl, M.; Peters, O.; Rossbach, J.; Schlarb, H.; Emma, P.J.; McCormick, D.; Ross, M.; Smith, T.J.; /SLAC

    2005-08-04

    At the DESY TTF2 linear accelerator three special techniques to characterize the longitudinal charge distribution of the electron bunches that drive the free-electron laser are currently under study: electro-optical sampling, far-infrared spectral analysis of coherent radiation and the use of a transverse deflecting cavity to streak the bunch. The principles and implementations of the latter two are described in this paper. Details on electro-optical sampling can be found in [1].

  19. Development of a Photothermal Absorbance Detector for Use with Microfluidic Devices

    PubMed Central

    Dennis, Patty J.; Ferguson Welch, Erin R.; Alarie, Jean Pierre; Ramsey, J. Michael; Jorgenson, James W.

    2010-01-01

    The development of a photothermal absorbance detector for use with microfluidic devices is described. Unlike thermooptical techniques that rely on measuring refractive index changes, the solution viscosity is probed by continuously monitoring solution conductivity. Platinum electrodes microfabricated on a quartz substrate and bonded to a substrate containing the microchannels enable contact conductivity measurements. The effects of excitation frequency and voltage, electrode spacing, laser power, and laser modulation (chopping) frequency were evaluated experimentally. In the current configuration a limit of detection of 5 nM for DABSYL-tagged glucosamine was obtained using long injections (to give flat-topped peaks). This corresponds to an absorbance of 4.4 × 10−7 AU. Separation and detection of DABSYL-tagged glycine, proline, and tryptophan is also shown to demonstrate the feasibility of the method. In addition, simulations were used to investigate the applicability of the technique to small volume platforms. PMID:20411923

  20. Defects of a-Si Thin-Film Solar Cells Detected by Transmission Photothermal Radiometric Imaging

    NASA Astrophysics Data System (ADS)

    Yan, Laijun; Gao, Chunming; Zhao, Binxing; Sun, Qiming; Liu, Lixian; Huan, Huiting

    2015-06-01

    The photothermal radiometry (PTR) technique is an effective non-destructive testing technique for detecting defects in materials. In this paper, a piece of commercial amorphous silicon (a-Si) thin-film solar cells with some artificial mechanical defects has been investigated by the transmission PTR imaging system. Firstly, a simplified analytical expression of a normalized transmission PTR signal was employed to characterize defects. Secondly, the corresponding experimental system has been set-up for obtaining several thermal images of the sample. Thirdly, different kinds of defects have been analyzed and identified by the thermal images. The results show that not only the artificial mechanical defects on the sample can be detected, but also some defects occurring in the manufacturing process can be detected by the transmission PTR imaging system.

  1. Combining two excitation wavelengths for pulsed photothermal profiling of hypervascular lesions in human skin.

    PubMed

    Majaron, B; Verkruysse, W; Tanenbaum, B S; Milner, T E; Telenkov, S A; Goodman, D M; Nelson, J S

    2000-07-01

    When pulsed photothermal radiometry (PPTR) is used for depth profiling of hypervascular lesions in human skin, melanin absorption also heats the most superficial skin layer (epidermis). Determination of lesion depth may be difficult when it lies close to the epidermal dermal junction, due to PPTR's limited spatial resolution. To overcome this problem, we have developed an approximation technique, which uses two excitation wavelengths (585 and 600 nm) to separate the vascular and epidermal components of the PPTR signal. This technique permits a noninvasive determination of lesion depth and epidermal thickness in vivo, even when the two layers are in close physical proximity to each other. Such information provides the physician with guidance in selecting the optimal parameters for laser therapy on an individual patient basis. PMID:10943928

  2. Noncontact surface temperature measurement by means of a modulated photothermal effect.

    PubMed

    Loarer, T; Greffet, J J; Huetz-Aubert, M

    1990-03-01

    The main problems when measuring surface temperature by means of radiometry (i.e., optical pyrometry) are the unknown emissivity and radiation reflected by the sample. The latter problem becomes critical when the sample is placed in hot surroundings, such as furnaces or combustion chambers; indeed, the reflected flux may then become larger than the emitted flux. In this paper we describe a novel technique, based on the photothermal effect, which allows the surface temperature to be measured without error due to reflected fluxes. The influence of the parameters of the experimental setup are discussed. Experimental data obtained with a sample placed inside a furnace are reported in the (300-1150 K) range. The experimental results show the efficiency of the technique which proves to be a general solution to extend the domain of application of optical pyrometry. PMID:20562945

  3. Coupler induced monopole component and its minimization in deflecting cavities

    NASA Astrophysics Data System (ADS)

    Ambattu, P. K.; Burt, G.; Grudiev, A.; Dolgashev, V.; Dexter, A.

    2013-06-01

    Deflecting cavities are used in particle accelerators for the manipulation of charged particles by deflecting or crabbing (rotating) them. For short deflectors, the effect of the power coupler on the deflecting field can become significant. The particular power coupler type can introduce multipole rf field components and coupler-specific wakefields. Coupler types that would normally be considered like standard on-cell coupler, waveguide coupler, or mode-launcher coupler could have one or two rf feeds. The major advantage of a dual-feed coupler is the absence of monopole and quadrupole rf field components in the deflecting structure. However, a dual-feed coupler is mechanically more complex than a typical single-feed coupler and needs a splitter. For most applications, deflecting structures are placed in regions where there is small space hence reducing the size of the structure is very desirable. This paper investigates the multipole field components of the deflecting mode in single-feed couplers and ways to overcome the effect of the monopole component on the beam. Significant advances in performance have been demonstrated. Additionally, a novel coupler design is introduced which has no monopole field component to the deflecting mode and is more compact than the conventional dual-feed coupler.

  4. Asteroid Deflection Mission Design Considering On-Ground Risks

    NASA Astrophysics Data System (ADS)

    Rumpf, Clemens; Lewis, Hugh G.; Atkinson, Peter

    The deflection of an Earth-threatening asteroid requires high transparency of the mission design process. The goal of such a mission is to move the projected point of impact over the face of Earth until the asteroid is on a miss trajectory. During the course of deflection operations, the projected point of impact will match regions that were less affected before alteration of the asteroid’s trajectory. These regions are at risk of sustaining considerable damage if the deflecting spacecraft becomes non-operational. The projected impact point would remain where the deflection mission put it at the time of mission failure. Hence, all regions that are potentially affected by the deflection campaign need to be informed about this risk and should be involved in the mission design process. A mission design compromise will have to be found that is acceptable to all affected parties (Schweickart, 2004). A software tool that assesses the on-ground risk due to deflection missions is under development. It will allow to study the accumulated on-ground risk along the path of the projected impact point. The tool will help determine a deflection mission design that minimizes the on-ground casualty and damage risk due to deflection operations. Currently, the tool is capable of simulating asteroid trajectories through the solar system and considers gravitational forces between solar system bodies. A virtual asteroid may be placed at an arbitrary point in the simulation for analysis and manipulation. Furthermore, the tool determines the asteroid’s point of impact and provides an estimate of the population at risk. Validation has been conducted against the solar system ephemeris catalogue HORIZONS by NASA’s Jet Propulsion Laboratory (JPL). Asteroids that are propagated over a period of 15 years show typical position discrepancies of 0.05 Earth radii relative to HORIZONS’ output. Ultimately, results from this research will aid in the identification of requirements for

  5. Nanoparticle-mediated photothermal effect enables a new method for quantitative biochemical analysis using a thermometer

    NASA Astrophysics Data System (ADS)

    Fu, Guanglei; Sanjay, Sharma T.; Dou, Maowei; Li, Xiujun

    2016-03-01

    A new biomolecular quantitation method, nanoparticle-mediated photothermal bioassay, using a common thermometer as the signal reader was developed. Using an immunoassay as a proof of concept, iron oxide nanoparticles (NPs) captured in the sandwich-type assay system were transformed into a near-infrared (NIR) laser-driven photothermal agent, Prussian blue (PB) NPs, which acted as a photothermal probe to convert the assay signal into heat through the photothermal effect, thus allowing sensitive biomolecular quantitation using a thermometer. This is the first report of biomolecular quantitation using a thermometer and also serves as the first attempt to introduce the nanoparticle-mediated photothermal effect for bioassays.A new biomolecular quantitation method, nanoparticle-mediated photothermal bioassay, using a common thermometer as the signal reader was developed. Using an immunoassay as a proof of concept, iron oxide nanoparticles (NPs) captured in the sandwich-type assay system were transformed into a near-infrared (NIR) laser-driven photothermal agent, Prussian blue (PB) NPs, which acted as a photothermal probe to convert the assay signal into heat through the photothermal effect, thus allowing sensitive biomolecular quantitation using a thermometer. This is the first report of biomolecular quantitation using a thermometer and also serves as the first attempt to introduce the nanoparticle-mediated photothermal effect for bioassays. Electronic supplementary information (ESI) available: Additional information on FTIR characterization (Fig. S1), photothermal immunoassay of PSA in human serum samples (Table S1), and the Experimental section, including preparation of antibody-conjugated iron oxide NPs, sandwich-type immunoassay, characterization, and photothermal detection protocol. See DOI: 10.1039/c5nr09051b

  6. Concrete deflection measurement using fiber optic distributed strain system

    NASA Astrophysics Data System (ADS)

    Papes, Martin; Jaros, Jakub; Fajkus, Marcel; Hurta, Jan; Liner, Andrej; Hruby, David; Vasinek, Vladimir

    2015-07-01

    The monitoring of building structures deformations and testing of construction materials resilience are very important processes in the development and production of given materials and structures. Undesirable or excessive deformations of materials are phenomena which are unacceptable in construction, especially in supporting structures. These issues are currently monitored by electromechanical sensor in most cases. It is a classic technique when the sensor measures the material stress at the point of its installation. This paper deals with the concrete deflection measurement using fiber optic distributed strain system. This system uses optical fiere as a sensor and operates at the principle of measurement of Brillouin frequencies. The mechanical stress on the optical fiber causes shift of these frequencies. This change is subsequently converted to stress unit micro-strain. In our experiments, the optical fiber was embedded in concrete along its whole length. The advantage of this system is that the measurement is carrying out along the entire fiber length with spatial resolution around 50 cm, so it is possible continuously measure several thousands of points at the distance of several kilometers.

  7. Optimization criteria for standing wave transverse magnetic deflection cavities

    SciTech Connect

    Haimson, J.

    1995-08-01

    An important linear accelerator requirement, in order to demonstrate narrow energy spectra, is the injection of electron bunches of narrow phase spread and negligible inter-bunch current. This can be achieved by r-f transverse modulation and clipping of the beam by an aperture prior to injection into the accelerator waveguide, i.e., chopper operation. By magnetically biasing the beam to one side of the centerline, it is possible to arrange for transmission into the accelerator at a time during each r-f cycle when the radial momentum imparted to the beam by the chopper cavity is passing through zero. The low efficiency of beam utilization normally associated with this type of operation, because of the high ratio of collected to transmitted current, can be considerably improved by combining the transverse chopping action with a suitably phased longitudinal velocity modulating field as obtained from a simple prebunching cavity. Transverse r-f deflection techniques also enable sub-harmonic bunch selection and injection into linear accelerators which are used as injectors for electron synchrotrons. This is achieved by driving the chopper cavity at the same frequency as the synchrotron r-f system (which is maintained at a precise sub-multiple of the linear accelerator fundamental frequency) and then prebunching the chopped beam at the fundamental frequency prior to injection into the linear accelerator.

  8. Computer Use May Help Deflect Seniors' Memory Problems

    MedlinePlus

    ... 157584.html Computer Use May Help Deflect Seniors' Memory Problems But, experts note that the study can' ... may help ward off age-related declines in memory and thinking, new research suggests. The study found ...

  9. High bandwidth deflection readout for atomic force microscopes.

    PubMed

    Steininger, Juergen; Bibl, Matthias; Yoo, Han Woong; Schitter, Georg

    2015-10-01

    This contribution presents the systematic design of a high bandwidth deflection readout mechanism for atomic force microscopes. The widely used optical beam deflection method is revised by adding a focusing lens between the cantilever and the quadrant photodetector (QPD). This allows the utilization of QPDs with a small active area resulting in an increased detection bandwidth due to the reduced junction capacitance. Furthermore the additional lens can compensate a cross talk between a compensating z-movement of the cantilever and the deflection readout. Scaling effects are analyzed to get the optimal spot size for the given geometry of the QPD. The laser power is tuned to maximize the signal to noise ratio without limiting the bandwidth by local saturation effects. The systematic approach results in a measured -3 dB detection bandwidth of 64.5 MHz at a deflection noise density of 62fm/√Hz. PMID:26520960

  10. High bandwidth deflection readout for atomic force microscopes

    NASA Astrophysics Data System (ADS)

    Steininger, Juergen; Bibl, Matthias; Yoo, Han Woong; Schitter, Georg

    2015-10-01

    This contribution presents the systematic design of a high bandwidth deflection readout mechanism for atomic force microscopes. The widely used optical beam deflection method is revised by adding a focusing lens between the cantilever and the quadrant photodetector (QPD). This allows the utilization of QPDs with a small active area resulting in an increased detection bandwidth due to the reduced junction capacitance. Furthermore the additional lens can compensate a cross talk between a compensating z-movement of the cantilever and the deflection readout. Scaling effects are analyzed to get the optimal spot size for the given geometry of the QPD. The laser power is tuned to maximize the signal to noise ratio without limiting the bandwidth by local saturation effects. The systematic approach results in a measured -3 dB detection bandwidth of 64.5 MHz at a deflection noise density of 62 fm / √{ Hz } .

  11. Shielded helix traveling wave cathode ray tube deflection structure

    DOEpatents

    Norris, N.J.; Hudson, C.L.

    1992-12-15

    Various embodiments of a helical coil deflection structure of a CRT are described and illustrated which provide shielding between adjacent turns of the coil on either three or four sides of each turn in the coil. Threaded members formed with either male or female threads and having the same pitch as the deflection coil are utilized for shielding the deflection coil with each turn of the helical coil placed between adjacent threads which act to shield each coil turn from adjacent turns and to confine the field generated by the coil to prevent or inhibit cross-coupling between adjacent turns of the coil to thereby prevent generation of fast fields which might otherwise deflect the beam out of time synchronization with the electron beam pulse. 13 figs.

  12. Shielded helix traveling wave cathode ray tube deflection structure

    DOEpatents

    Norris, Neil J.; Hudson, Charles L.

    1992-01-01

    Various embodiments of a helical coil deflection structure of a CRT are described and illustrated which provide shielding between adjacent turns of the coil on either three or four sides of each turn in the coil. Threaded members formed with either male or female threads and having the same pitch as the deflection coil are utilized for shielding the deflection coil with each turn of the helical coil placed between adjacent threads which act to shield each coil turn from adjacent turns and to confine the field generated by the coil to prevent or inhibit cross-coupling between adjacent turns of the coil to thereby prevent generation of fast fields which might otherwise deflect the beam out of time synchronization with the electron beam pulse.

  13. Limitation of linear colliders from transverse rf deflections

    SciTech Connect

    Seeman, J.T.

    1987-01-01

    Offaxis beam trajectories in a linear collider produce transverse wakefield and chromatic effects which cause emittance enlargement. One cause for non-centered trajectories in the accelerating structures is radial rf fields which produce transverse deflections. Static deflections can be compensated by static dipole magnetic fields. However, fluctuations of the rf fields cause variations in the deflections which must be managed or limited. Given the level of fluctuation of the phase and amplitude of an rf system, a limit on the allowable rf deflection can be calculated. Parameters, such as the beam emittance, lattice design, rf wavelength and the initial and final beam energies, influence the tolerances. Two tolerances are calculated: (1) one assumes that the wakefields are completely controlled, and that chromatic effects are the only enlarging mechanism (optimistic), and (2) the other assumes the limit is due to transverse wakefields without the aid of Landau damping (pessimistic).

  14. Physical and thermal properties of human teeth determined by photomechanical, photothermal images to rapidly diagnose

    NASA Astrophysics Data System (ADS)

    Elsharkawy, Yasser H.

    2009-02-01

    This paper details the current techniques for the detection of caries using non-invasive techniques, A promising option is tooth trans-illumination which is based on an increase of light scattering or light absorption in the affected tissue region. In this study trans-illumination applied to detect microscopic caries lesions was investigated using premolar teeth containing affected caries lesions. One line coincides with a carious absorption line, while the other is used as a reference. By this referencing the system is auto-calibrated continuously. Normal and carious human teeth were applied for the determination of NIR absorption by using a micro-spectrophotometer. Relative NIR absorption value for normal tooth and for carious one distributed in different quantity relating to the tooth structure, whereas the value showed much higher in enamel than in dentine. This paper suggests a way to use a commercially available system, which has the capability to carious detection. It is based on photomechanical and photothermal monitoring of teeth response. This technique is based on irradiation of the teeth with a short pulse Nd:YAG laser (1064 μm, 12 ns) and monitoring the laser-induced local thermal effects. This is realized with thermal imagers that locate the heated teeth absorbing zones. The photothermal (PT) image represents a two-dimensional depth-integrated temperature distribution in the irradiated volume and correlates with the conventional optical absorption coefficients. In addition to a description as to how each of the modalities function, consideration is given to recent advances and changes in the relevant technologies, and a comparison of relative benefits and shortfalls of the systems.

  15. Deflected jet experiments in a turbulent combustor flowfield. Ph.D. Thesis Final Report

    NASA Technical Reports Server (NTRS)

    Ferrell, G. B.; Lilley, D. G.

    1985-01-01

    Experiments were conducted to characterize the time-mean and turbulent flow field of a deflected turbulent jet in a confining cylindrical crossflow. Jet-to-crossflow velocity ratios of 2, 4, and 6 were investigated, under crossflow inlet swirler vane angles of 0 (swirler removed), 45 and 70 degrees. Smoke, neutrally buoyant helium-filled soap bubbles, and multi-spark flow visualization were employed to highlight interesting features of the deflected jet, as well as the tracjectory and spread pattern of the jet. A six-position single hot-wire technique was used to measure the velocities and turbulent stresses in nonswirling crossflow cases. In these cases, measurements confirmed that the deflected jet is symmetrical about the vertical plan passing through the crossflow axis, and the jet penetration was found to be reduced from that of comparable velocity ratio infinite crossflow cases. In the swirling crossflow cases, the flow visualization techniques enabled gross flow field characterization to be obtained for a range of lateral jet-to-crossflow velocity ratios and a range of inlet swirl strengths in the main flow.

  16. Double deflection system for an electron beam device

    DOEpatents

    Parker, Norman W.; Golladay, Steven D.; Crewe, Albert V.

    1978-01-01

    A double deflection scanning system for electron beam instruments is provided embodying a means of correcting isotropic coma, and anisotropic coma aberrations induced by the magnetic lens of such an instrument. The scanning system deflects the beam prior to entry into the magnetic lens from the normal on-axis intersection of the beam with the lens according to predetermined formulas and thereby reduces the aberrations.

  17. Design of Superconducting Parallel Bar Deflecting and Crabbing rf Structures

    SciTech Connect

    Jean Delayen, Haipeng Wang

    2009-05-01

    A new concept for a deflecting and crabbing rf structure based on half-wave resonant lines was introduced recently*. It offers significant advantages to existing designs and, because of it compactness, allows low frequency operation. This concept has been further refined and optimized for superconducting implementation. Results of this optimization and application to a 400 MHz crabbing cavity and a 499 MHz deflecting cavity are presented.

  18. Optimization of Deflection of a Big NEO through Impact with a Small One

    PubMed Central

    Zhu, Kaijian; Huang, Weiping; Wang, Yuncai; Niu, Wei; Wu, Gongyou

    2014-01-01

    Using a small near-Earth object (NEO) to impact a larger and potentially threatening NEO has been suggested as an effective method to avert a collision with Earth. This paper develops a procedure for analysis of the technique for specific NEOs. First, an optimization method is used to select a proper small body from the database. Some principles of optimality are achieved with the optimization process. Then, the orbit of the small body is changed to guarantee that it flies toward and impacts the big threatening NEO. Kinetic impact by a spacecraft is chosen as the strategy of deflecting the small body. The efficiency of this method is compared with that of a direct kinetic impact to the big NEO by a spacecraft. Finally, a case study is performed for the deflection of the Apophis NEO, and the efficiency of the method is assessed. PMID:25525627

  19. Nanoshell-enabled photothermal cancer therapy: impending clinical impact.

    PubMed

    Lal, Surbhi; Clare, Susan E; Halas, Naomi J

    2008-12-01

    Much of the current excitement surrounding nanoscience is directly connected to the promise of new nanoscale applications in cancer diagnostics and therapy. Because of their strongly resonant light-absorbing and light-scattering properties that depend on shape, noble metal nanoparticles provide a new and powerful tool for innovative light-based approaches. Nanoshellsspherical, dielectric core, gold shell nanoparticleshave been central to the development of photothermal cancer therapy and diagnostics for the past several years. By manipulating nanoparticle shape, researchers can tune the optical resonance of nanoshells to any wavelength of interest. At wavelengths just beyond the visible spectrum in the near-infrared, blood and tissue are maximally transmissive. When nanoshell resonances are tuned to this region of the spectrum, they become useful contrast agents in the diagnostic imaging of tumors. When illuminated, they can serve as nanoscale heat sources, photothermally inducing cell death and tumor remission. As nanoshell-based diagnostics and therapeutics move from laboratory studies to clinical trials, this Account examines the highly promising achievements of this approach in the context of the challenges of this complex disease. More broadly, these materials present a concrete example of a highly promising application of nanochemistry to a biomedical problem. We describe the properties of nanoshells that are relevant to their preparation and use in cancer diagnostics and therapy. Specific surface chemistries are necessary for passive uptake of nanoshells into tumors and for targeting specific cell types by bioconjugate strategies. We also describe the photothermal temperature increases that can be achieved in surrogate structures known as tissue phantoms and the accuracy of models of this effect using heat transport analysis. Nanoshell-based photothermal therapy in several animal models of human tumors have produced highly promising results, and we include

  20. Post mitigation impact risk analysis for asteroid deflection demonstration missions

    NASA Astrophysics Data System (ADS)

    Eggl, Siegfried; Hestroffer, Daniel; Thuillot, William; Bancelin, David; Cano, Juan L.; Cichocki, Filippo

    2015-08-01

    Even though mankind believes to have the capabilities to avert potentially disastrous asteroid impacts, only the realization of mitigation demonstration missions can validate this claim. Such a deflection demonstration attempt has to be cost effective, easy to validate, and safe in the sense that harmless asteroids must not be turned into potentially hazardous objects. Uncertainties in an asteroid's orbital and physical parameters as well as those additionally introduced during a mitigation attempt necessitate an in depth analysis of deflection mission designs in order to dispel planetary safety concerns. We present a post mitigation impact risk analysis of a list of potential kinetic impactor based deflection demonstration missions proposed in the framework of the NEOShield project. Our results confirm that mitigation induced uncertainties have a significant influence on the deflection outcome. Those cannot be neglected in post deflection impact risk studies. We show, furthermore, that deflection missions have to be assessed on an individual basis in order to ensure that asteroids are not inadvertently transported closer to the Earth at a later date. Finally, we present viable targets and mission designs for a kinetic impactor test to be launched between the years 2025 and 2032.

  1. MOSFET solid state switching circuit improves the 0 to 99% rise time for framing camera deflection electronics

    SciTech Connect

    Rivera, A.T.; Thomas, S.

    1996-09-01

    We have improved the 0 to 99% rise time voltage on our 2 frame deflection plates from 160 to 65 nS with the addition of a peaking circuit that works in conjunction with our primary 2 frame deflection circuitry. Our peaking technique has applications to other HV pulsers including those which must drive 51 ohm loads. Generally, rise time voltages are measured between 10 and 90%. To minimize the camera image blur resulting from the dynamic influence of deflection plate potentials acting on photocathode electrons, it was necessary to design a circuit that would rise from 0 to the 99% voltage level in under 100nS. Once this voltage was reached, it was necessary to stay within 1% of the attained voltage level for a duration of 1 uS. This was accomplished with the use of MOSFET solid state switching.

  2. Photothermal determination of thermal diffusivity and polymerization depth profiles of polymerized dental resins

    NASA Astrophysics Data System (ADS)

    Martínez-Torres, P.; Mandelis, A.; Alvarado-Gil, J. J.

    2009-12-01

    The degree and depth of curing due to photopolymerization in a commercial dental resin have been studied using photothermal radiometry. The sample consisted of a thick layer of resin on which a thin metallic gold layer was deposited, thus guaranteeing full opacity. Purely thermal-wave inverse problem techniques without the interference of optical profiles were used. Thermal depth profiles were obtained by heating the gold coating with a modulated laser beam and by performing a frequency scan. Prior to each frequency scan, photopolymerization was induced using a high power blue light emitted diode (LED). Due to the highly light dispersive nature of dental resins, the polymerization process depends strongly on optical absorption of the blue light, thereby inducing a depth dependent thermal diffusivity profile in the sample. A robust depth profilometric method for reconstructing the thermal diffusivity depth dependence on degree and depth of polymerization has been developed. The thermal diffusivity depth profile was linked to the polymerization kinetics.

  3. Objective characterization of bruise evolution using photothermal depth profiling and Monte Carlo modeling.

    PubMed

    Vidovič, Luka; Milanič, Matija; Majaron, Boris

    2015-01-01

    Pulsed photothermal radiometry (PPTR) allows noninvasive determination of laser-induced temperature depth profiles in optically scattering layered structures. The obtained profiles provide information on spatial distribution of selected chromophores such as melanin and hemoglobin in human skin. We apply the described approach to study time evolution of incidental bruises (hematomas) in human subjects. By combining numerical simulations of laser energy deposition in bruised skin with objective fitting of the predicted and measured PPTR signals, we can quantitatively characterize the key processes involved in bruise evolution (i.e., hemoglobin mass diffusion and biochemical decomposition). Simultaneous analysis of PPTR signals obtained at various times post injury provides an insight into the variations of these parameters during the bruise healing process. The presented methodology and results advance our understanding of the bruise evolution and represent an important step toward development of an objective technique for age determination of traumatic bruises in forensic medicine. PMID:25554972

  4. Determination of optical properties of turbid media using pulsed photothermal radiometry.

    PubMed

    Prahl, S A; Vitkin, I A; Bruggemann, U; Wilson, B C; Anderson, R R

    1992-06-01

    Pulsed photothermal radiometry (PPTR) measures blackbody radiation emitted by a sample after absorption of an optical pulse. Three techniques for obtaining the absorption coefficient of absorbing-only, semi-infinite samples are examined and shown to give comparable results. An analytic theory for the time dependence of the PPTR signal in semi-infinite scattering and absorbing media has been derived and tested in a series of controlled gel phantoms. This theory, based on the diffusion approximation of the radiative transport equation, is shown to model the time course of the detected signal accurately. Furthermore, when the incident fluence is known, the theory can be used in a non-linear, two-parameter fitting algorithm to determine the absorption and reduced scattering coefficients of a turbid sample with an accuracy of 10-15% for transport albedos ranging from 0.42-0.88. PMID:1626021

  5. Correlation Between Chemical Composition of Silver Alloys and Photothermal Radiometry Signals

    NASA Astrophysics Data System (ADS)

    Rojas-Rodríguez, I.; Velázquez-Hernández, R.; Jaramillo-Vigueras, D.; Mendoza-López, M. L.; Millan-Malo, M.; Rodíguez-García, M. E.

    2012-12-01

    The development of nondestructive and noncontact techniques for evaluation of metallic materials is invaluable to metal characterization. The photothermal radiometry (PTR) amplitude and phase images of silver alloys were used to study the silver distribution in alloys rich in silver and copper for Ag concentrations between 37 mass% and 92 mass%. The silver concentration was determined using inductively coupled plasma. It was found that for Ag concentrations lower than 50 mass%, the PRT signals are governed by the thermal and optical properties of copper and vice versa. It was possible to establish a good correlation between the PTR amplitude and phase signal with the Ag concentration. This means that after calibration it is possible to determine the Ag concentration using nondestructive evaluation.

  6. Photothermal radiometric determination of thermal diffusivity depth profiles in a dental resin

    NASA Astrophysics Data System (ADS)

    Martínez-Torres, P.; Mandelis, A.; Alvarado-Gil, J. J.

    2010-03-01

    The depth of curing due to photopolymerization in a commercial dental resin is studied using photothermal radiometry. The sample consists of a thick layer of resin on which a thin metallic layer is deposited guaranteeing full opacity of the sample. In this case, purely thermal-wave inverse problem techniques without the interference of optical profiles can be used. Thermal profiles are obtained by heating the coating with a modulated laser beam and performing a modulation frequency scan. Before each frequency scan, photopolymerization was induced using a high power blue LED. However due to the fact that dental resins are highly light dispersive materials, the polymerization process depends strongly on the optical absorption coefficient inducing a depth dependent thermal diffusion in the sample. It is shown that using a robust depth profilometric inverse method one can reconstruct the thermal diffusivity profile of the photopolymerized resin.

  7. Use of Photothermally Generated Seebeck Voltage for Thermal Characterization of Thermoelectric Materials

    NASA Astrophysics Data System (ADS)

    Kuriakose, Maju; Depriester, Michael; King, Roch Chan Yu; Roussel, Frédérick; Sahraoui, Abdelhak Hadj

    2014-06-01

    A simple and accurate experimental procedure to measure simultaneously the thermal properties (conductivity, diffusivity, and effusivity) of thermoelectric (TE) materials using their Seebeck voltage is proposed. The technique is based on analysis of a periodically oscillating thermoelectric signal generated from a TE material when it is thermally excited using an intensity-modulated laser source. A self-normalization procedure is implemented in the presented method using TE signals generated by changing the laser heating from one side to another of the TE material. Experiments are done on a polyaniline carbon nanohybrid (6.6 wt.% carbon nanotubes), yielding a thermal conductivity of 1.106 ± 0.001 W/m-K. The results are compared with the results from photothermal infrared radiometry experiments.

  8. Investigation of Thermal Properties of SiC Ceramics Containing Carbon Nanostructures by Photothermal Measurements

    NASA Astrophysics Data System (ADS)

    Kaźmierczak-Bałata, Anna; Mazur, Jacek; Bodzenta, Jerzy; Trefon-Radziejewska, Dominika; Drewniak, Łukasz

    2014-12-01

    This work presents an analysis of the influence of graphene reinforcement on properties of silicon carbide composites. Samples were prepared by a spark plasma sintering method. The density and hardness were obtained in the preliminary experiments. The thermal diffusivity was determined by the continuous wave photothermal technique with detection based on infrared radiometry. The thermal diffusivity is in the range of (0.48 to 0.57) cms for samples prepared from granulated SiC and in the range of (0.56 to 0.71) cms for samples prepared from SiC powder. Thermal properties are correlated with the density of SiC ceramics. The thermal diffusivity of samples with a higher density is lower in comparison to samples with a lower density.

  9. Quantitative photothermal heating and cooling measurements of engineered nanoparticles in an optical trap

    NASA Astrophysics Data System (ADS)

    Roder, Paden Bernard

    Laser tweezers and optical trapping has provided scientists and engineers a unique way to study the wealth of phenomena that materials exhibit at the micro- and nanoscale, much of which remains mysterious. Of particular interest is the interplay between light absorption and subsequent heat generation of laser-irradiated materials, especially due to recent interest in developing nanoscale materials for use as agents for photothermal cancer treatments. An introduction to optical trapping physics and laser tweezers are given in Chapter 1 and 2 of this thesis, respectively. The remaining chapters, summarized below, describe the theoretical basis of laser heating of one-dimensional nanostructures and experiments in which optically-trapped nanostructures are studied using techniques developed for a laser tweezer. In Chapter 3, we delve into the fundamentals of laser heating of one-dimensional materials by developing an analytical model of pulsed laser heating of uniform and tapered supported nanowires and compare calculations with experimental data to comment on the effects that the material's physical, optical, and thermal parameters have on its heating and cooling rates. We then consider closed-form analytical solutions for the temperature rise within infinite circular cylinders with nanometer-scale diameters irradiated at right angles by TM-polarized continuous-wave laser sources, which allows for analysis of laser-heated nanowires in a solvated environment. The infinite nanowire analysis will then be extended to the optical heating of laser-irradiated finite nanowires in the framework of a laser tweezer, which enables predictive capabilities and direct comparison with laser trapping experiments. An effective method for determining optically-trapped particle temperatures as well as the temperature gradient in the surrounding medium will be discussed in Chapter 4. By combining laser tweezer calibration techniques, forward-scattered light power spectrum analysis, and

  10. Objective characterization of bruise evolution using photothermal depth profiling and Monte Carlo modeling

    NASA Astrophysics Data System (ADS)

    Vidovič, Luka; Milanič, Matija; Majaron, Boris

    2015-01-01

    Pulsed photothermal radiometry (PPTR) allows noninvasive determination of laser-induced temperature depth profiles in optically scattering layered structures. The obtained profiles provide information on spatial distribution of selected chromophores such as melanin and hemoglobin in human skin. We apply the described approach to study time evolution of incidental bruises (hematomas) in human subjects. By combining numerical simulations of laser energy deposition in bruised skin with objective fitting of the predicted and measured PPTR signals, we can quantitatively characterize the key processes involved in bruise evolution (i.e., hemoglobin mass diffusion and biochemical decomposition). Simultaneous analysis of PPTR signals obtained at various times post injury provides an insight into the variations of these parameters during the bruise healing process. The presented methodology and results advance our understanding of the bruise evolution and represent an important step toward development of an objective technique for age determination of traumatic bruises in forensic medicine.

  11. Millisecond ordering of block-copolymer films via photo-thermal gradients

    SciTech Connect

    Majewski, Pawel W.; Yager, Kevin G.

    2015-03-12

    For the promise of self-assembly to be realized, processing techniques must be developed that simultaneously enable control of the nanoscale morphology, rapid assembly, and, ideally, the ability to pattern the nanostructure. Here, we demonstrate how photo-thermal gradients can be used to control the ordering of block-copolymer thin films. Highly localized laser heating leads to intense thermal gradients, which induce a thermophoretic force on morphological defects. This increases the ordering kinetics by at least 3 orders-of-magnitude, compared to conventional oven annealing. By simultaneously exploiting the thermal gradients to induce shear fields, we demonstrate uniaxial alignment of a block-copolymer film in less than a second. Finally, we provide examples of how control of the incident light-field can be used to generate prescribed configurations of block-copolymer nanoscale patterns.

  12. Contact resonance atomic force microscopy imaging in air and water using photothermal excitation

    NASA Astrophysics Data System (ADS)

    Kocun, Marta; Labuda, Aleksander; Gannepalli, Anil; Proksch, Roger

    2015-08-01

    Contact Resonance Force Microscopy (CR-FM) is a leading atomic force microscopy technique for measuring viscoelastic nano-mechanical properties. Conventional piezo-excited CR-FM measurements have been limited to imaging in air, since the "forest of peaks" frequency response associated with acoustic excitation methods effectively masks the true cantilever resonance. Using photothermal excitation results in clean contact, resonance spectra that closely match the ideal frequency response of the cantilever, allowing unambiguous and simple resonance frequency and quality factor measurements in air and liquids alike. This extends the capabilities of CR-FM to biologically relevant and other soft samples in liquid environments. We demonstrate CR-FM in air and water on both stiff silicon/titanium samples and softer polystyrene-polyethylene-polypropylene polymer samples with the quantitative moduli having very good agreement between expected and measured values.

  13. Contact resonance atomic force microscopy imaging in air and water using photothermal excitation

    SciTech Connect

    Kocun, Marta; Labuda, Aleksander; Gannepalli, Anil; Proksch, Roger

    2015-08-15

    Contact Resonance Force Microscopy (CR-FM) is a leading atomic force microscopy technique for measuring viscoelastic nano-mechanical properties. Conventional piezo-excited CR-FM measurements have been limited to imaging in air, since the “forest of peaks” frequency response associated with acoustic excitation methods effectively masks the true cantilever resonance. Using photothermal excitation results in clean contact, resonance spectra that closely match the ideal frequency response of the cantilever, allowing unambiguous and simple resonance frequency and quality factor measurements in air and liquids alike. This extends the capabilities of CR-FM to biologically relevant and other soft samples in liquid environments. We demonstrate CR-FM in air and water on both stiff silicon/titanium samples and softer polystyrene-polyethylene-polypropylene polymer samples with the quantitative moduli having very good agreement between expected and measured values.

  14. Millisecond ordering of block-copolymer films via photo-thermal gradients

    DOE PAGESBeta

    Majewski, Pawel W.; Yager, Kevin G.

    2015-03-12

    For the promise of self-assembly to be realized, processing techniques must be developed that simultaneously enable control of the nanoscale morphology, rapid assembly, and, ideally, the ability to pattern the nanostructure. Here, we demonstrate how photo-thermal gradients can be used to control the ordering of block-copolymer thin films. Highly localized laser heating leads to intense thermal gradients, which induce a thermophoretic force on morphological defects. This increases the ordering kinetics by at least 3 orders-of-magnitude, compared to conventional oven annealing. By simultaneously exploiting the thermal gradients to induce shear fields, we demonstrate uniaxial alignment of a block-copolymer film in lessmore » than a second. Finally, we provide examples of how control of the incident light-field can be used to generate prescribed configurations of block-copolymer nanoscale patterns.« less

  15. Rosetta observations of solar wind deflection in the coma

    NASA Astrophysics Data System (ADS)

    Broiles, Thomas; Burch, James; Clark, George; Goldstein, Raymond; Koenders, Christoph; Mandt, Kathleen; Mokashi, Prachet; Samara, Marilia

    2015-04-01

    Until recently, study of the solar wind around comets was limited to remote observations and brief in-situ encounters. With the arrival of Rosetta at the comet Churyumov-Gerasimenko (CG), we have had near constant solar wind observations at the comet for over 6 months. This is an unprecedented opportunity to study this dynamic interaction over time. Neutral atoms produced by the comet become ionized through photoionization or charge-exchange with the solar wind. The freshly ionized particles experience v x B electric field and begin to gyrate around the interplanetary magnetic field. Currently, CG is ~2.6 AU from the Sun, and as of this writing, neutral production is still relatively low. Consequently, most pickup ions are produced locally (< few hundred kilometers), and a diamagnetic cavity may not exist. Moreover, neutral production is variable and changes over the comet's rotational period. We find the following: 1) The solar wind is heavily deflected near the comet (in some cases >45° away from the anti-sunward direction). 2) The solar wind helium experiences less deflection than the protons. 3) The periodicity of the deflection is highly variable, and can vary over minutes or hours. From these results, we conclude that the solar wind is deflected by a mechanism very close to the comet. We suggest the following possibilities: 1) The solar wind could be deflected by a Lorenz force in the opposite direction to that experienced by the pickup ions, which would also conserve the momentum of the two fluid system. This would explain why solar wind protons are more strongly deflected than the heavier alpha particles. Additionally, this would explain the periodicity of the deflections, which would react to changes in the interplanetary magnetic field. 2) The solar wind deflection might occur from strong charging of comet's nucleus. In which case, the nucleus may charge both positively or negatively. The nucleus could charge positively due photoionization of the surface

  16. Multifunctional diagnostic, nanothermometer, and photothermal nano-devices

    NASA Astrophysics Data System (ADS)

    Green, Kory; Wirth, Janina; O'Connor, Megan; Lim, Shuang Fang

    2015-08-01

    Photothermal treatment is a valuable part of cancer therapies, in which the temperature of the heated region must rise to at least 40-45°C for protein destruction to occur[1, 2]. In practice, heating temperature distributions are typically non-uniform, resulting in incomplete kill of cancer cells. Gold nanorods (AuNRs) show strong absorption in the near infrared which leads to a strong plasmonic photothermal (PPT) effect. However, basic scientific understanding of AuNR local temperature and heat transfer to local surroundings has not been investigated in detail. In our study, the near infrared (NIR) excited Upconversion nanoparticle (UCNP)-AuNR nanostructure combines the powerful diagnostic and thermal sensing capacity of UCNPs, with the known therapeutic property of AuNRs. We show enhanced upconverted emission with AuNRs coupling, improving diagnostic capacity of the construct. We demonstrate mapping of the temperature profile within tumor tissue phantom medium, at high spatial and temporal sensitivity.

  17. Photothermally excited force modulation microscopy for broadband nanomechanical property measurements

    NASA Astrophysics Data System (ADS)

    Wagner, Ryan; Killgore, Jason P.

    2015-11-01

    We demonstrate photothermally excited force modulation microscopy (PTE FMM) for mechanical property characterization across a broad frequency range with an atomic force microscope (AFM). Photothermal excitation allows for an AFM cantilever driving force that varies smoothly as a function of drive frequency, thus avoiding the problem of spurious resonant vibrations that hinder piezoelectric excitation schemes. A complication of PTE FMM is that the sub-resonance cantilever vibration shape is fundamentally different compared to piezoelectric excitation. By directly measuring the vibrational shape of the cantilever, we show that PTE FMM is an accurate nanomechanical characterization method. PTE FMM is a pathway towards the characterization of frequency sensitive specimens such as polymers and biomaterials with frequency range limited only by the resonance frequency of the cantilever and the low frequency limit of the AFM.

  18. Photothermally excited force modulation microscopy for broadband nanomechanical property measurements

    SciTech Connect

    Wagner, Ryan Killgore, Jason P.

    2015-11-16

    We demonstrate photothermally excited force modulation microscopy (PTE FMM) for mechanical property characterization across a broad frequency range with an atomic force microscope (AFM). Photothermal excitation allows for an AFM cantilever driving force that varies smoothly as a function of drive frequency, thus avoiding the problem of spurious resonant vibrations that hinder piezoelectric excitation schemes. A complication of PTE FMM is that the sub-resonance cantilever vibration shape is fundamentally different compared to piezoelectric excitation. By directly measuring the vibrational shape of the cantilever, we show that PTE FMM is an accurate nanomechanical characterization method. PTE FMM is a pathway towards the characterization of frequency sensitive specimens such as polymers and biomaterials with frequency range limited only by the resonance frequency of the cantilever and the low frequency limit of the AFM.

  19. Reduced Graphene Oxide Nanosheet for Chemo-photothermal Therapy.

    PubMed

    Cheon, Yeong Ah; Bae, Jun Hyuk; Chung, Bong Geun

    2016-03-22

    The protein-functionalized reduced graphene oxide (rGO) nanosheet is of great interest in stimuli-responsive drug delivery and controlled release applications. We developed doxorubicin (DOX)-loaded bovine serum albumin (BSA)-functionalized rGO (DOX-BSA-rGO) nanosheets. To investigate the reduction of BSA-functionalized GO nanosheets and drug loading efficiency, we used X-ray photoelectron spectroscopy (XPS) and UV-visible spectrophotometer analysis. DOX-BSA-rGO nanosheets exhibited dose-dependent cellular uptake without any cytotoxic effect. We also demonstrated near-infrared (NIR)-induced chemo-photothermal therapy of brain tumor cells treated with DOX-BSA-rGO nanosheets. Therefore, this DOX-BSA-rGO nanosheet could be a powerful tool for chemo-photothermal therapy applications. PMID:26930106

  20. Dependence of Photothermal Conversion Characteristics on Different Nanoparticle Dispersions.

    PubMed

    Zhang, Hui; Chen, Hui-Jiuan; Du, Xiaoze; Lin, Guiping; Wen, Dongsheng

    2015-04-01

    The efficiency of nanoparticle-based direct absorption solar collector (DASC) is strongly dependent on the materials, where a systematic study is still lacking. This work conducts an experimental study of the photothermal conversion characteristics of a number of nanoparticle dispersions including Au, Si, Fe3O4, Al2O3 and diamond under the same experimental setup. The results show that comparing with the base fluid, the introduction of nanoparticles can increase the photothermal conversion efficiency significantly, and the efficiency increases in the order of Al2O3, diamond, (Fe3O4 and Si) and Au. For a given total mass concentration, the Fe3O4-Au hybrid nanofluid is found to possess a higher efficiency than that of pure Au alone. Three possible mechanisms are proposed for the influence of nanoparticle materials, which can qualitatively explain the experimental results. PMID:26353535

  1. Preparation of Gold Nanorods and Their Applications in Photothermal Therapy.

    PubMed

    Xia, Kai; Zhang, Liming; Huang, Yuanfu; Lu, Zhuoxuan

    2015-01-01

    Gold nanorods (GNRs) have recently been widely studied due to their unique optical and electronic properties which are dependent on their shape, size, and aspect ratio. Seed-mediated growth method has become the most widely method for the synthesis of GNRs due to its advantages of simplicity of procedure, high yield of nanorods, and ease of aspect ratio controlling. Moreover, GNRs are especially attractive candidates for exploitation in photothermal therapy since they can be readily synthesized with various aspect ratios, which enable GNRs to selectively absorb the near-infrared (NIR) light. This review is focused on summarizing the preparation of GNRs by seed-mediated growth method and their applications in photothermal therapy. PMID:26328306

  2. Linear and non-linear deflection analysis of thick rectangular plates. 2: Numerical applications

    NASA Astrophysics Data System (ADS)

    Bencharif, N.; Ng, S. F.

    1994-03-01

    literature. The submatrices involved in the formation of the finite difference equations from the governing differential equations are generated directly by the computer program. The subroutine SOLINV using the change of variable technique illustrated elsewhere takes care of the solution of the general system. Simplicity in formulation and quick convergence are the obvious advantages of the finite difference formulation developed to compute small and large deflection analysis of thick plates in comparison with other numerical methods requiring extensive computer facilities.

  3. Photothermal characterization of solid two-layer spherical structures

    NASA Astrophysics Data System (ADS)

    Xie, Guangxi; Chen, Zhifeng; Wang, Chinhua; Mandelis, Andreas

    2010-03-01

    A theoretical model for evaluating 2-layer solid spherical samples that are heated by a modulated light is presented using the Green function method. The specific Green's function corresponding to the composite structure has been derived. The characteristics of the thermal-wave field with respect to the thermophysical properties of the material and the geometrical factors are presented. Experimental results obtained with laser infrared photothermal radiometry show the capability of the model for characterizing the spherical layered structures.

  4. Optimization of mid-IR photothermal imaging for tissue analysis

    NASA Astrophysics Data System (ADS)

    Totachawattana, Atcha; Erramilli, Shyamsunder; Sander, Michelle Y.

    2015-08-01

    Photothermal imaging in the mid-infrared enables highly sensitive, label-free microscopy by relying on bond-specific characterization of functional groups within the samples. In a pump-probe configuration, the mid-infrared (mid-IR) pump laser is tuned to characteristic vibrational modes and through localized absorption thermal changes in the refractive index are induced. The shorter wavelength probe scatter can be detected with lock-in technology, utilizing highly sensitive detectors at telecommunication wavelengths. This mitigates the need of complex detector technology as required for traditional infrared spectroscopy/Fourier Transform Infrared Spectroscopy. The presented photothermal system integrates a high brightness quantum cascade laser that can be tuned continuously over a spectral range of interest with a fiber probe laser. Fiber laser technology features a compact footprint and offers robust performance metrics and reduced sensitivity to environmental perturbations compared to free-space laser configurations. In systematic spectroscopy studies where the probe laser parameters were modified, we demonstrate that the signal-to-noise ratio can be significantly enhanced by utilizing a mode-locked laser compared to a continuous-wave laser. With a raster-scanning approach, photothermal spectroscopy can be extended to hyperspectral label-free mid-infrared imaging to combine spectral content with localized sample details. By tuning the pump laser to the amide-I absorption band around 1650 cm-1 in biological tissue samples, the spectral characteristics can provide insight into the secondary structure of proteins (e.g. amyloid plaques; alpha-helix, beta-sheet). We present the versatility of our mid-IR photothermal system by analyzing histopathological tissue sections of cancerous tissue in a non-contact, non-destructive approach with good sensitivity.

  5. Direct Nuclear Delivery of DNA by Photothermal Nanoblade.

    PubMed

    Wu, Ting-Hsiang; Wu, Yi-Chien; Sagullo, Enrico; Teitell, Michael A; Chiou, Pei-Yu

    2015-12-01

    We demonstrate direct nuclear delivery of DNA into live mammalian cells using the photothermal nanoblade. Pulsed laser-triggered cavitation bubbles on a titanium-coated micropipette tip punctured both cellular plasma and nuclear membranes, which was followed by pressure-controlled delivery of DNA into the nucleus. High-level and efficient plasmid expression in different cell types with maintained cell viability was achieved. PMID:25900925

  6. Handbook of photothermal test data on encapsulant materials

    NASA Technical Reports Server (NTRS)

    Liang, R. H.; Oda, K. L.; Chung, S. Y.; Smith, M. V.; Gupta, A.

    1983-01-01

    Laboratory tests performed to characterize candidate encapsulation materials with respect to changes in their physical and chemical properties caused by photothermal aging are described. Several key material properties relating directly to material degradation and deterioration of performance were identified and were monitored as functions of aging conditions and time. A status report on accelerated testing activities is provided and experimental data are presented. It will be updated periodically as more data become available.

  7. Deflection-Compensating Beam for use inside a Cylinder

    NASA Technical Reports Server (NTRS)

    Goodman, Dwight; Myers, Neill; Herren, Kenneth

    2008-01-01

    A design concept for a beam for a specific application permits variations and options for satisfying competing requirements to minimize certain deflections under load and to minimize the weight of the beam. In the specific application, the beam is required to serve as a motion-controlled structure for supporting a mirror for optical testing in the lower third portion of a horizontal, cylindrical vacuum chamber. The cylindrical shape of the chamber is fortuitous in that it can be (and is) utilized as an essential element of the deflection-minimizing design concept. The beam is, more precisely, a table-like structure comprising a nominally flat, horizontal portion with vertical legs at its ends. The weights of the beam and whatever components it supports are reacted by the contact forces between the lower ends of the legs and the inner cylindrical chamber wall. Whereas the bending moments arising from the weights contribute to a beam deflection that is concave with its lowest point at midlength, the bending moments generated by the contact forces acting on the legs contribute to a beam deflection that is convex with its highest point at midlength. In addition, the bending of the legs in response to the weights causes the lower ends of the legs to slide downward on the cylindrical wall. By taking the standard beam-deflection equations, combining them with the geometric relationships among the legs and the horizontal portion of the beam, and treating the sliding as a component of deflection, it is possible to write an equation for the net vertical deflection as a function of the load and of position along the beam. A summary of major conclusions drawn from the equation characterization is included.

  8. Nonintrusive noncontacting frequency-domain photothermal radiometry of caries

    NASA Astrophysics Data System (ADS)

    El-Sharkawy, Yasser H.; Abd-Elwahab, Bassam

    2010-04-01

    Among diffusion methods, photothermal radiometry (PTR) has the ability to penetrate and yield information about an opaque medium well beyond the range of conventional optical imaging. Owing to this ability, pulsed-laser PTR has been extensively used in turbid media such as biological tissues to study the sub-surface deposition of laser radiation, a task that may be difficult or impossible for many optical methods due to excessive scattering and absorption. In this paper considers the achievements of Pulsed Photothermal Radiometry using IR camera in the investigation of physical properties of biological materials and the diagnostics of the interaction of laser radiation with biological materials. A three-dimensional heat conduction formulation with the use of three-dimensional optical diffusion is developed to derive a turbid frequency-domain PTR model. The present photo-thermal model for frequency-domain PTR may prove useful for non-contact; non-invasive, in situ evaluate the depth profilometric imaging capabilities of FDPTR in monitoring carious and artificial subsurface lesions in human teeth.

  9. Cancer treatment by photothermal, photochemical, and photobiological interactions

    NASA Astrophysics Data System (ADS)

    Chen, Wei R.; Korbelik, Mladen; Liu, Hong; Nordquist, Robert E.

    2005-01-01

    Laser tissue interactions hold great promise in cancer treatment. Photothermal interaction aims at the direct cell destruction through the increase of local tissue temperature, while photochemical interaction aims at the cell destruction using free radicals produced through the activation of photosensitizers in the target tissue. Photobiological interaction can target the immune host system to induce long-term control. Photothermal and photochemical interactions can be significantly enhanced by photobiological interaction through the use of immunoadjuvants. In our experiments, three different immunoadjuvants, complete Freund"s adjuvant (CF), incomplete Freund"s adjuvant (IF), and c-parvum (CP), were used in the treatment of metastatic mammary tumors in conjunction with photothermal interaction. In addition, a specific adjuvant, Glycated chitosan (GC), has been used in combination with photodynamic therapy (PDT) in the treatment of mouse tumors. In the treatment of rat tumors, CF, IF and CP raised the cure-rates from 0% to 18%, 7% and 9%, respectively. In comparison, GC resulted in a 29% long-term survival. In the treatment of EMT6 mammary sarcoma in mice, GC of 0.5% and 1.5% concentrations increased the cure rates of Photofrin-based PDT treatment from 38% to 63% and 75%, respectively. In the treatment of Line 1 lung adenocarcinoma in mice, a 1.67% GC solution enabled a non-curative mTHPC-based PDT to cure a 37% of the tumor bearing mice.

  10. Near-infrared fiber delivery systems for interstitial photothermal therapy

    NASA Astrophysics Data System (ADS)

    Slatkine, Michael; Mead, Douglass S.; Konwitz, Eli; Rosenberg, Zvi

    1995-05-01

    Interstitial photothermal coagulation has long been recognized as a potential important, minimally invasive modality for treating a variety of pathologic conditions. We present two different technologies for interstitial photothermal coagulation of tissue with infrared lasers: An optical fiber with a radially symmetric diffusing tip for deep coagulation, and a flat bare fiber for the coagulation of thin and long lesions by longitudinally moving the fiber while lasing in concert. Urology and Gynecology Fibers: The fibers are 600 microns diameter with 20 - 40 mm frosted distal tips protected by a smooth transparent cover. When used with a Neodymium:YAG (Nd:YAG) laser, the active fiber surface diffuses optical radiation in a radial pattern, delivering up to 40 W power, and thus providing consistent and uniform interstitial photothermal therapy. Coagulation depth ranges from 4 to 15 mm. Animal studies in the United States and clinical studies in Europe have demonstrated the feasibility of using these fibers to treat benign prostatic hyperplasia and endometrial coagulation. Rhinology Fiber: The fiber is an 800 micron diameter flat fiber operated at 8 W power level while being interstitially pushed and pulled along its axis. A long and thin coagulated zone is produced. The fiber is routinely used for the shrinking of hypertrophic turbinates without surrounding and bone mucusal damage in ambulatory environments.

  11. Preparation of gold nanoparticle aggregates and their photothermal heating property.

    PubMed

    Kim, Jun-Hyun; Lavin, Brian W

    2011-01-01

    This report describes simple synthetic strategies to prepare partially aggregated gold nanoparticles (GNPs) and their ability to produce photothermally-induced heating of an aqueous medium upon exposure to broadband light. The formation of various GNPs and their aggregates were accomplished in the absence of surfactants at room temperature. The morphologies, structures, and absorption properties of these GNPs were carefully characterized. Given that the resulting GNPs possessing strong and wide absorption bands fall in the most intense solar radiation spectrum, the photothermally-induced heating of water was examined in the presence of the GNPs via irradiation with a solar simulator (i.e., 100 mW/cm2; 1-sun condition). Our GNPs exhibited a slightly greater increase in the water temperature (3-4 degrees C) than that of conventional citrate-stabilized GNPs. This superior photothermal heating property of our GNPs directly indicated that the intense and broad absorption band effectively improved the conversion of highly absorbed photon energy into heat. PMID:21446405

  12. PEGylated Copper Nanowires as a Novel Photothermal Therapy Agent.

    PubMed

    Li, Kuei-Chang; Chu, Hsun-Chen; Lin, Yow; Tuan, Hsing-Yu; Hu, Yu-Chen

    2016-05-18

    Metal nanowires are promising for their applications including electrical connectors, transparent conductive electrodes and conductive additives, but the use of metal nanowires as photothermal agents to convert light to heat has yet to be reported. Here we synthesized dispersible polyethylene glycol-coated (PEGylated) copper nanowires (CuNWs) and showed for the first time that PEGylated CuNWs were able to convert near-infrared (NIR, 808 nm) light into heat at a photothermal efficiency of 12.5%. The PEGylated CuNWs exhibited good reusability and enabled rapid temperature rise to >50 °C in 6 min by NIR irradiation. The PEGylated CuNWs were flexible and intertwined around the cancer cells, which, upon NIR irradiation, allowed for direct heat transmission to cells and effectively triggered cancer cell ablation in vitro. Intratumoral injection of PEGylated CuNWs into colon tumor-bearing mice and ensuing NIR irradiation for 6 min significantly raised the local temperature to >50 °C, induced necrosis, and suppressed tumor growth. Compared with other NIR light absorbing noble metal-based nanomaterials, PEGylated CuNWs are relatively easy to synthesize in both laboratory and large scales using the low cost copper. This study demonstrated the potential of PEGylated CuNWs as a new cost-effective photothermal agent, and paved a new avenue to using CuNWs for cancer therapy. PMID:27111420

  13. Cooperative Nanoparticle System for Photothermal Tumor Treatment without Skin Damage.

    PubMed

    Piao, Ji-Gang; Liu, Dong; Hu, Kan; Wang, Limin; Gao, Feng; Xiong, Yujie; Yang, Lihua

    2016-02-01

    How to ablate tumors without using skin-harmful high laser irradiance remains an ongoing challenge for photothermal therapy. Here, we achieve this with a cooperative nanosystem consisting of gold nanocage (AuNC) "activator" and a cationic mammalian-membrane-disruptive peptide, cTL, as photothermal antenna and anticancer agent, respectively. Specifically, this nanosystem is prepared by grafting cTL onto AuNC via a Au-S bond, followed by attachment of thiolated polyethylene glycol (PEG) for stealth effects. Upon NIR irradiation at skin-permissible dosage, the resulting cTL/PEG-AuNC nanoparticle effectively ablates both irradiated and nonirradiated cancer cells, likely owing to cTL being responsively unleashed by intracellular thiols exposed to cTL/PEG-AuNC via membrane damage initiated by AuNC's photothermal effects and deteriorated by the as-released cTL. When administered systematically in a mouse model, cTL/PEG-AuNC populates tumors through their porous vessels and effectively destroys them without damaging skin. PMID:26794418

  14. Photothermal lens detection of gold nanoparticles: theory and experiments.

    PubMed

    Brusnichkin, Anton V; Nedosekin, Dmitry A; Proskurnin, Mikhail A; Zharov, Vladimir P

    2007-11-01

    An approach for mode-mismatched two-beam (pump-probe) photothermal lens detection of multipoint light-absorbing targets in solution (e.g., gold nanoparticles) is developed for continuous-wave intensity-modulated laser-excitation mode. A description of the blooming of the thermooptical element (thermal lens) upon absorption of the excitation laser radiation is based on the summation of individual thermal waves from multiple heat sources. This description makes it possible to estimate the irregularities of the temperature (and, thus, the refractive index) profile for a discrete number of nanoparticles in the irradiated area and a change in the concentration and particle size parameters. Experimental results are in good agreement with theoretical dependences of the photothermal signal on nanoparticle size and concentration and excitation laser power. Calibration plots for particles from 2 to 250 nm show long linear ranges, limits of detection of gold nanoparticles at the level of hundreds of nanoparticles with the current setup, and the photothermal-lens sensitivity coefficient increases as a cubic function of particle size. Further improvements are discussed, including increasing the sensitivity thresholds up to one nanoparticle in the detected volume. PMID:18028698

  15. Principle of Equivalence and the Deflection of Light by the Sun

    ERIC Educational Resources Information Center

    Comer, Robert P.; Lathrop, John D.

    1978-01-01

    Explains the discrepancy between the principle-of-equivalence and the general theory of relativity in calculating the deflection of light by the sun. Shows that the total deflection is the sum of the deflection given by the principle-of-equivalence, and the deflection of infinitely fast particles. ( GA)

  16. Carbon-Coated Gold Nanorods: A Facile Route to Biocompatible Materials for Photothermal Applications.

    PubMed

    Kaneti, Yusuf Valentino; Chen, Chuyang; Liu, Minsu; Wang, Xiaochun; Yang, Jia Lin; Taylor, Robert Allen; Jiang, Xuchuan; Yu, Aibing

    2015-11-25

    Gold nanorods and their core-shell nanocomposites have been widely studied because of their well-defined anisotropy and unique optical properties and applications. This study demonstrates a facile hydrothermal synthesis strategy for generating carbon coating on gold nanorods (AuNRs@C) under mild conditions (<200 °C), where the carbon shell is composed of polymerized sugar molecules (glucose). The structure and composition of the produced core-shell nanocomposites were characterized using advanced microscopic and spectroscopic techniques. The functional properties, particularly the photothermal and biocompatibility properties of the produced AuNRs@C, were quantified to assess their potential in photothermal hyperthermia. These AuNRs@C were tested in vitro (under representative treatment conditions) using near-infrared (NIR) light irradiation. It was found that the AuNRs produced here exhibit exemplary heat generation capability. Temperature changes of 10.5, 9, and 8 °C for AuNRs@C were observed with carbon shell thicknesses of 10, 17, and 25 nm, respectively, at a concentration of 50 μM, after 600 s of irradiation with a laser power of 0.17 W/cm(2). In addition, the synthesized AuNRs@C also exhibit good biocompatibility toward two soft tissue sarcoma cell lines (HT1080, a fibrosarcoma; and GCT, a fibrous histiocytoma). The cell viability study shows that AuNRs@C (at a concentration of <0.1 mg/mL) core-shell particles induce significantly lower cytotoxicity on both HT1080 and GCT cell lines, as compared with cetyltrimethylammonium bromide (CTAB)-capped AuNRs. Furthermore, similar to PEG-modified AuNRs, they are also safe to both HT1080 and GCT cell lines. This biocompatibility results from a surface full of -OH or -COH groups, which are suitable for linking and are nontoxic Therefore, the AuNRs@C represent a viable alternative to PEG-coated AuNRs for facile synthesis and improved photothermal conversion. Overall, these findings open up a new class of carbon

  17. Rapid design and optimization of low-thrust rendezvous/interception trajectory for asteroid deflection missions

    NASA Astrophysics Data System (ADS)

    Li, Shuang; Zhu, Yongsheng; Wang, Yukai

    2014-02-01

    Asteroid deflection techniques are essential in order to protect the Earth from catastrophic impacts by hazardous asteroids. Rapid design and optimization of low-thrust rendezvous/interception trajectories is considered as one of the key technologies to successfully deflect potentially hazardous asteroids. In this paper, we address a general framework for the rapid design and optimization of low-thrust rendezvous/interception trajectories for future asteroid deflection missions. The design and optimization process includes three closely associated steps. Firstly, shape-based approaches and genetic algorithm (GA) are adopted to perform preliminary design, which provides a reasonable initial guess for subsequent accurate optimization. Secondly, Radau pseudospectral method is utilized to transcribe the low-thrust trajectory optimization problem into a discrete nonlinear programming (NLP) problem. Finally, sequential quadratic programming (SQP) is used to efficiently solve the nonlinear programming problem and obtain the optimal low-thrust rendezvous/interception trajectories. The rapid design and optimization algorithms developed in this paper are validated by three simulation cases with different performance indexes and boundary constraints.

  18. On Possibility of Direct Asteroid Deflection by Electric Solar Wind Sail

    NASA Astrophysics Data System (ADS)

    Merikallio, Sini; Janhunen, Pekka

    2010-05-01

    The Electric Solar Wind Sail (E-sail) is a new propulsion method for interplanetary travel which was invented in 2006 and is currently under development. The E-sail uses charged tethers to extract momentum from the solar wind particles to obtain propulsive thrust. According to current estimates, the E-sail is 2-3 orders of magnitude better than traditional propulsion methods (chemical rockets and ion engines) in terms of produced lifetime-integrated impulse per propulsion system mass. Here we analyze the problem of using the E-sail for directly deflecting an Earth-threatening asteroid. The problem then culminates into how to attach the E-sail device to the asteroid. We assess a number of alternative attachment strategies and arrive at a recommendation of using the gravity tractor method because of its workability for a wide variety of asteroid types. We also consider possible techniques to scale up the E-sail force beyond the baseline one Newton level to deal with more imminent or larger asteroid or cometary threats. As a baseline case we consider a 3 million ton asteroid which can be deflected with a baseline 1 N E-sail in 5-10 years. Once developed, the E-sail would appear to provide a safe and reasonably low-cost way of deflecting dangerous asteroids and other heavenly bodies in cases where the collision threat becomes known several years in advance.

  19. Study of beamlet deflection and its compensations in a MeV accelerator

    SciTech Connect

    Kashiwagi, Mieko; Inoue, Takashi; Taniguchi, Masaki; Umeda, Naotaka; Dairaku, Masayuki; Takemoto, Jumpei; Tobari, Hiroyuki; Tsuchida, Kazuki; Watanabe, Kazuhiro; Yamanaka, Haruhiko; Sakamoto, Keishi; Grisham, Larry R.

    2011-09-26

    In a five stage multi-aperture and multi-grid (MAMuG) accelerator in JAEA, beam acceleration tests are in progress toward 1 MeV, 200 A/m{sup 2} H{sup -} ion beams for ITER. The 1 MV voltage holding has been successfully demonstrated for 4,000 s with the accelerator of expanded gap length that lowered local electric field concentrations. This led to increase of the beam energy up to 900 keV-level. However, it was found that beamlets were deflected more in long gaps and direct interceptions of the deflected beamlet caused breakdowns. The beamlet deflection and its compensation methods were studied utilizing a three-dimensional multi beamlet analysis. The analysis showed that the 1 MeV beam can be compensated by a combination of the aperture offset of 0.8 mm applied in the electron suppression (ESG) and the metal bar called a field shaping plate with a thickness of 1 mm attached beneath the ESG. The paper reports these compensation methods and analytical predictions, with experimental results of the MAMuG accelerator in which those compensation techniques have been applied.

  20. Quantitative Analysis of CME Deflections in the Corona

    NASA Astrophysics Data System (ADS)

    Gui, Bin; Shen, Chenglong; Wang, Yuming; Ye, Pinzhong; Liu, Jiajia; Wang, Shui; Zhao, Xuepu

    2011-07-01

    In this paper, ten CME events viewed by the STEREO twin spacecraft are analyzed to study the deflections of CMEs during their propagation in the corona. Based on the three-dimensional information of the CMEs derived by the graduated cylindrical shell (GCS) model (Thernisien, Howard, and Vourlidas in Astrophys. J. 652, 1305, 2006), it is found that the propagation directions of eight CMEs had changed. By applying the theoretical method proposed by Shen et al. ( Solar Phys. 269, 389, 2011) to all the CMEs, we found that the deflections are consistent, in strength and direction, with the gradient of the magnetic energy density. There is a positive correlation between the deflection rate and the strength of the magnetic energy density gradient and a weak anti-correlation between the deflection rate and the CME speed. Our results suggest that the deflections of CMEs are mainly controlled by the background magnetic field and can be quantitatively described by the magnetic energy density gradient (MEDG) model.

  1. Deflected Propagation ---- A Factor Deciding the Geoeffectiveness of A CME

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Shen, C.; Liu, J.; Gui, B.; Wang, S.

    2010-12-01

    To answer the question if a CME can cause a significant change of the states of geo-space, the first issue we have to address is whether or not the CME will intersect with the Earth or what the trajectory of the CME is. From several observational cases and statistical studies, we show that the deflected propagations of CMEs are a common phenomenon. The amount of the deflection could be as large as several tens degrees in either latitude, longitude or both. Thus, an on-disk CME may not necessarily encounter the Earth, while a limb CME may be able to hit the Earth. Roughly, the CMEs' deflections can be classified as two different kinds. One is the deflection occurring in the corona, in which the CME's trajectory is controled by the distribution of the energy density of undisturbed coronal magnetic field. The other is that happenning in the IP space and in the ecliptic plane, in which the direction of the CME's propagation will be changed by the preceding or trailing background solar wind plasma depending on the velocity difference between the CME and ambient solar wind. Two models are proposed to describe the two different CME deflection behaviors, respectively. By applying the models to several cases, we may show that the trajectories of these CMEs predicted by the models match the observations fairly well.

  2. Physically-synthesized gold nanoparticles containing multiple nanopores for enhanced photothermal conversion and photoacoustic imaging.

    PubMed

    Park, Jisoo; Kang, Heesung; Kim, Young Heon; Lee, Sang-Won; Lee, Tae Geol; Wi, Jung-Sub

    2016-08-25

    Physically-synthesized gold nanoparticles having a narrow size distribution and containing multiple nanopores have been utilized as photothermal converters and imaging contrast agents. Nanopores within the gold nanoparticles make it possible to increase the light-absorption cross-section and consequently exhibit distinct improvements in photothermal conversion and photoacoustic imaging efficiencies. PMID:27527067

  3. Photothermal radiometry probing of scars in the internal surface of a thin metal tube.

    PubMed

    Li, P Z; Zhou, G Y

    1992-07-01

    The principle and equipment of photothermal radiometry probing of scars in the internal surface of a thin metal tube are described. By measuring the amplitude frequency characteristics of the photothermal signal, we calculated the depth of the scars in the internal surface of a sample. PMID:20725353

  4. In vivo photothermal optical coherence tomography for non-invasive imaging of endogenous absorption agents

    PubMed Central

    Makita, Shuichi; Yasuno, Yoshiaki

    2015-01-01

    In vivo photothermal optical coherence tomography (OCT) is demonstrated for cross-sectional imaging of endogenous absorption agents. In order to compromise the sensitivity, imaging speed, and sample motion immunity, a new photothermal detection scheme and phase processing method are developed. Phase-resolved swept-source OCT and fiber-pigtailed laser diode (providing excitation at 406 nm) are combined to construct a high-sensitivity photothermal OCT system. OCT probe and excitation beam coaxially illuminate and are focused on tissues. The photothermal excitation and detection procedure is designed to obtain high efficiency of photothermal effect measurement. The principle and method of depth-resolved cross-sectional imaging of absorption agents with photothermal OCT has been derived. The phase-resolved thermal expansion detection algorithm without motion artifact enables in vivo detection of photothermal effect. Phantom imaging with a blood phantom and in vivo human skin imaging are conducted. A phantom with guinea-pig blood as absorber has been scanned by the photothermal OCT system to prove the concept of cross-sectional absorption agent imaging. An in vivo human skin measurement is also performed with endogenous absorption agents. PMID:26137374

  5. Engineering on-chip nanoporous gold material libraries via precision photothermal treatment

    NASA Astrophysics Data System (ADS)

    Chapman, Christopher A. R.; Wang, Ling; Biener, Juergen; Seker, Erkin; Biener, Monika M.; Matthews, Manyalibo J.

    2015-12-01

    Libraries of nanostructured materials on a single chip are a promising platform for high throughput and combinatorial studies of structure-property relationships in the fields of physics and biology. Nanoporous gold (np-Au), produced by an alloy corrosion process, is a nanostructured material specifically suited for such studies because of its self-similar thermally induced coarsening behavior. However, traditional heat application techniques for the modification of np-Au are bulk processes that cannot be used to generate a library of different pore sizes on a single chip. Here, laser micro-processing offers an attractive solution to this problem by providing a means to apply energy with high spatial and temporal resolution. In the present study we use finite element multiphysics simulations to predict the effects of laser mode (continuous-wave vs. pulsed) and thermal conductivity of the supporting substrate on the local np-Au film temperatures during photothermal annealing. Based on these results we discuss the mechanisms by which the np-Au network is coarsened. Thermal transport simulations predict that continuous-wave mode laser irradiation of np-Au thin films on a silicon substrate supports the widest range of morphologies that can be created through photothermal annealing of np-Au. Using the guidance provided by simulations, we successfully fabricate an on-chip material library consisting of 81 np-Au samples of 9 different morphologies for use in the parallel study of structure-property relationships.Libraries of nanostructured materials on a single chip are a promising platform for high throughput and combinatorial studies of structure-property relationships in the fields of physics and biology. Nanoporous gold (np-Au), produced by an alloy corrosion process, is a nanostructured material specifically suited for such studies because of its self-similar thermally induced coarsening behavior. However, traditional heat application techniques for the modification

  6. Temperature-feedback upconversion nanocomposite for accurate photothermal therapy at facile temperature

    NASA Astrophysics Data System (ADS)

    Zhu, Xingjun; Feng, Wei; Chang, Jian; Tan, Yan-Wen; Li, Jiachang; Chen, Min; Sun, Yun; Li, Fuyou

    2016-02-01

    Photothermal therapy (PTT) at present, following the temperature definition for conventional thermal therapy, usually keeps the temperature of lesions at 42-45 °C or even higher. Such high temperature kills cancer cells but also increases the damage of normal tissues near lesions through heat conduction and thus brings about more side effects and inhibits therapeutic accuracy. Here we use temperature-feedback upconversion nanoparticle combined with photothermal material for real-time monitoring of microscopic temperature in PTT. We observe that microscopic temperature of photothermal material upon illumination is high enough to kill cancer cells when the temperature of lesions is still low enough to prevent damage to normal tissue. On the basis of the above phenomenon, we further realize high spatial resolution photothermal ablation of labelled tumour with minimal damage to normal tissues in vivo. Our work points to a method for investigating photothermal properties at nanoscale, and for the development of new generation of PTT strategy.

  7. Synthesis of WS2 Nanowires as Efficient 808 nm-Laser-Driven Photothermal Nanoagents.

    PubMed

    Macharia, Daniel K; Yu, Nuo; Zhong, Runzhi; Xiao, Zhiyin; Yang, Jianmao; Chen, Zhigang

    2016-06-01

    A prerequisite for the development of photothermal ablation therapy for cancer is to obtain efficient photothermal nanoagents that can be irradiated by near-infrared (NIR) laser. Herein, we have reported the synthesis of WS2 nanowires as photothermal nanoagents by the reaction of WCl6 with CS2 in oleylamine at 280 degrees C. WS2 nanowires have the thickness of -2 nm and length of -100 nm. Importantly, the chloroform dispersion of WS2 nanowires exhibits strong photoabsorption in NIR region. The temperature of the dispersion (0.10-0.50 mg/mL) can increase by 12.8-23.9 degrees C in 5 min under the irradiation of 808 nm laser with a power density of 0.80 W/cm2. Therefore, WS2 nanowires have a great superiority as a new nanoagent for NIR-induced photothermal ablation of cancer, due to their small size and excellent photothermal performance. PMID:27427645

  8. Large and small deflections of a cantilever beam

    NASA Astrophysics Data System (ADS)

    Beléndez, Tarsicio; Neipp, Cristian; Beléndez, Augusto

    2002-05-01

    The classical problem of the deflection of a cantilever beam of linear elastic material, under the action of an external vertical concentrated load at the free end, is analysed. We present the differential equation governing the behaviour of this physical system and show that this equation, although straightforward in appearance, is in fact rather difficult to solve due to the presence of a non-linear term. In this sense, this system is similar to another well known physical system: the simple pendulum. An approximation of the behaviour of a cantilever beam for small deflections was obtained from the equation for large deflections, and we present various numerical results for both cases. Finally, we compare the theoretical results with the experimental results obtained in the laboratory.

  9. A wideband deflected reflection based on multiple resonances

    NASA Astrophysics Data System (ADS)

    Chen, Hongya; Ma, Hua; Wang, Jiafu; Qu, Shaobo; Li, Yongfeng; Wang, Jun; Yan, Mingbao; Pang, Yongqiang

    2015-07-01

    We propose to realize wideband deflected reflection in microwave regime through multiple resonances. A wideband deflected reflection of a phase gradient metasurface is designed using a double-head arrow structure, which has demonstrated an ultra-wideband cross-polarized reflection caused by multiple electric and magnetic resonances. The wideband effect benefits from the wideband cross-polarized reflection and flexible phase modulation of the double-head arrow structure. Simulated and experimental results agree well with theoretical predictions. Furthermore, relative bandwidths of deflected reflection reach to 71 % for both x- and y-polarized waves under normal incidence. Our method of expansion bandwidth may pave the way in many practical applications, such as RCS reduction, stealth surfaces.

  10. Development of pneumatic thrust-deflecting powered-lift systems

    NASA Technical Reports Server (NTRS)

    Englar, R. J.; Nichols, J. H., Jr.; Harris, M. J.; Eppel, J. C.; Shovlin, M. D.

    1986-01-01

    Improvements introduced into the Circulation Control Wing/Upper Surface Blowing (CCW/USB) STOL concept (Harris et al., 1982) are described along with results of the full-scale static ground tests and model-scale wind tunnel investigations. Tests performed on the full-scale pneumatic thrust-deflecting system installed on the NASA QSRA aircraft have demonstrated that, relative to the original baseline configuration, a doubling of incremental thrust deflection due to blowing resulted from improvements that increased the blowing span and momentum, as well as from variations in blowing slot height and geometry of the trailing edge. A CCW/Over the Wing model has been built and tested, which was shown to be equivalent to the CCW/USB system in terms of pneumatic thrust deflection and lift generation, while resolving the problem of cruise thrust loss due to exhaust scrubbing on the wing upper surface.

  11. Analysis of the Deflection of CMEs by Coronal Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Liewer, Paulett C.; Panasenco, O.; Vourlidas, A.

    2013-07-01

    Understanding coronal influences on the direction of propagation of CMEs is important for space weather prediction. It is well known that CMEs often propagate non-radially, e.g., they do not move out radially from the location of the solar source (see, e.g., Cremades and Bothmer, A&A, 2004; Panasenco et al., Sol. Phys. 2013). There is evidence that most CMEs exit the corona in the minimum field region surrounding the coronal/heliospheric current sheet (HCS). If this is the case, then the degree of deflection should reflect the distance of the source region from the current sheet region. Here we study the observed deflection in latitude of four CMEs using STEREO/SECCHI’s EUV and white light observations to trace the deflection. A potential-field source surface (PFSS) model (Schrijver & DeRosa, Sol. Phys. 2003) is used to give information on the magnetic forces acting on the CME at different heights in the lower corona. This model, as well as the PFSS model results at the GONG website (http://gong.nso.edu/data/magmap/archive.html) and the coronal observations from STEREO, are used to try to determine the location of the HCS. For the events studied, we find cases when the deflection is gradual (occurring between the surface at several solar radii) and cases where the deflection is immediate (within ~1.5 solar radii). There are many cases in the literature where CMEs originating at high latitude are deflected towards the ecliptic and eventually impact Earth. Several of the CMEs we analyzed were later detected in situ at ~1 AU and we compare the near-Sun trajectory information to the trajectory information determine from the in situ information.

  12. Novel deflecting cavity design for eRHIC

    SciTech Connect

    Wu, Q.; Belomestnykh, S.; Ben-Zvi, I.

    2011-07-25

    To prevent significant loss of the luminosity due to large crossing angle in the future ERL based Electron Ion Collider at BNL (eRHIC), there is a demand for crab cavities. In this article, we will present a novel design of the deflecting/crabbing 181 MHz superconducting RF cavity that will fulfil the requirements of eRHIC. The quarter-wave resonator structure of the new cavity possesses many advantages, such as compact size, high R{sub t}/Q, the absence of the same order mode and lower order mode, and easy higher order mode damping. We will present the properties and characteristics of the new cavity in detail. As the accelerator systems grow in complexity, developing compact and efficient deflecting cavities is of great interest. Such cavities will benefit situations where the beam line space is limited. The future linac-ring type electron-ion collider requires implementation of a crab-crossing scheme for both beams at the interaction region. The ion beam has a long bunches and high rigidity. Therefore, it requires a low frequency, large kicking angle deflector. The frequency of the deflecting mode for the current collider design is 181 MHz, and the deflecting angle is {approx}5 mrad for each beam. At such low frequency, the previous designs of the crab cavities will have very large dimensions, and also will be confronted by typical problems of damping the Lower Order Mode (LOM), the Same Order Mode (SOM), and as usual, the Higher Order Modes (HOM). In this paper we describe how one can use the concept of a quarter-wave (QW) resonator for a deflecting/crabbing cavity, and use its fundamental mode to deflect the beam. The simplicity of the cavity geometry and the large separation between its fundamental mode and the first HOM make it very attractive.

  13. Experimental testing and computational modeling of flat oval duct deflection

    SciTech Connect

    Smolinski, P.J.; Palmer, G.S.

    1998-10-01

    The deflection characteristics of spiral seam flat oval HVAC duct are examined in this study, and the effects of duct size, wall thickness, and the size spacing, and type of external reinforcement on the duct deformation are investigated. A duct test setup and a deflection measurement frame were developed for measuring the deformation of flat oval duct, and experimental testing was performed on a variety of duct configurations to measure the duct deflections at various positive and negative internal pressures. Finite element computer models of the ducts were developed to predict the deflections. The correlation between the predictions of the computer model and the data from the experimental testing is highly variable with differences ranging from a few percent to several hundred percent. In general, it was found that there was closer agreement between the finite element results and the experimental measurements for smaller duct and at locations of type 2 external reinforcements. This may be due to the fact that the finite element model assumed the idealized flat oval shape and this shape was better matched by smaller ducts and near the external reinforcement. It was also found that in some cases, unreinforced duct could achieve higher pressures than type 1 reinforced duct before exceeding the deflection limits. Sources of error include the uneven surface of the mastic in the measurement of the duct joint deflection and the variance of the actual duct shape from the idealized shape used in the finite element model. This study did not examine the variability of the experimental results due to differences in duct shape or manufacture.

  14. Nuclear cycler: An incremental approach to the deflection of asteroids

    NASA Astrophysics Data System (ADS)

    Vasile, Massimiliano; Thiry, Nicolas

    2016-04-01

    This paper introduces a novel deflection approach based on nuclear explosions: the nuclear cycler. The idea is to combine the effectiveness of nuclear explosions with the controllability and redundancy offered by slow push methods within an incremental deflection strategy. The paper will present an extended model for single nuclear stand-off explosions in the proximity of elongated ellipsoidal asteroids, and a family of natural formation orbits that allows the spacecraft to deploy multiple bombs while being shielded by the asteroid during the detonation.

  15. The 1919 measurement of the deflection of light

    NASA Astrophysics Data System (ADS)

    Will, Clifford M.

    2015-06-01

    The measurement of the deflection of starlight during a total solar eclipse on 29 May 1919 was the first verification of general relativity by an external team of scientists, brought Einstein and his theory to the attention of the general public, and left a legacy of experimental testing that continues today. The discovery of gravitational lenses turned Einstein's deflection into an important tool for astronomy and cosmology. This article reviews the history of the 1919 measurement and other eclipse measurements, describes modern measurements of the effect using radio astronomy, and of its cousin, the Shapiro time delay, and discusses the discovery and impact of gravitational lenses.

  16. Optical caliper with compensation for specimen deflection and method

    DOEpatents

    Bernacki, Bruce E.

    1997-01-01

    An optical non-contact profilometry system and method provided by an optical caliper with matched optical sensors that are arranged conjugate to each other so that the surface profile and thickness of an article can be measured without using a fixed reference surface and while permitting the article to deflect in space within the acquisition range of the optical sensors. The output signals from the two optical sensors are algebraically added to compensate for any such deflection of the article and provide a so compensated signal, the balance and sign of which provides a measurement of the actual thickness of the article at the optical sensors.

  17. Optical caliper with compensation for specimen deflection and method

    DOEpatents

    Bernacki, B.E.

    1997-12-09

    An optical non-contact profilometry system and method provided by an optical caliper with matched optical sensors that are arranged conjugate to each other so that the surface profile and thickness of an article can be measured without using a fixed reference surface and while permitting the article to deflect in space within the acquisition range of the optical sensors. The output signals from the two optical sensors are algebraically added to compensate for any such deflection of the article and provide a so compensated signal, the balance and sign of which provides a measurement of the actual thickness of the article at the optical sensors. 2 figs.

  18. Fast scan control for deflection type mass spectrometers

    NASA Technical Reports Server (NTRS)

    Yeager, P. R.; Gaetano, G.; Hughes, D. B. (Inventor)

    1974-01-01

    A high speed scan device is reported that allows most any scanning sector mass spectrometer to measure preselected gases at a very high sampling rate. The device generates a rapidly changing staircase output which is applied to the accelerator of the spectrometer and it also generates defocusing pulses that are applied to one of the deflecting plates of the spectrometer which when shorted to ground deflects the ion beam away from the collector. A defocusing pulse occurs each time there is a change in the staircase output.

  19. Multiplexed Force and Deflection Sensing Shell Membranes for Robotic Manipulators

    NASA Technical Reports Server (NTRS)

    Park, Yong-Lae; Black, Richard; Moslehi, Behzad; Cutkosky, Mark; Chau, Kelvin

    2012-01-01

    Force sensing is an essential requirement for dexterous robot manipulation, e.g., for extravehicular robots making vehicle repairs. Although strain gauges have been widely used, a new sensing approach is desirable for applications that require greater robustness, design flexibility including a high degree of multiplexibility, and immunity to electromagnetic noise. This invention is a force and deflection sensor a flexible shell formed with an elastomer having passageways formed by apertures in the shell, with an optical fiber having one or more Bragg gratings positioned in the passageways for the measurement of force and deflection.

  20. Porous Pd nanoparticles with high photothermal conversion efficiency for efficient ablation of cancer cells

    NASA Astrophysics Data System (ADS)

    Xiao, Jia-Wen; Fan, Shi-Xuan; Wang, Feng; Sun, Ling-Dong; Zheng, Xiao-Yu; Yan, Chun-Hua

    2014-03-01

    Nanoparticle (NP) mediated photothermal effect shows great potential as a noninvasive method for cancer therapy treatment, but the development of photothermal agents with high photothermal conversion efficiency, small size and good biocompatibility is still a big challenge. Herein, we report Pd NPs with a porous structure exhibiting enhanced near infrared (NIR) absorption as compared to Pd nanocubes with a similar size (almost two-fold enhancement with a molar extinction coefficient of 6.3 × 107 M-1 cm-1), and the porous Pd NPs display monotonically rising absorbance from NIR to UV-Vis region. When dispersed in water and illuminated with an 808 nm laser, the porous Pd NPs give a photothermal conversion efficiency as high as 93.4%, which is comparable to the efficiency of Au nanorods we synthesized (98.6%). As the porous Pd NPs show broadband NIR absorption (650-1200 nm), this allows us to choose multiple laser wavelengths for photothermal therapy. In vitro photothermal heating of HeLa cells in the presence of porous Pd NPs leads to 100% cell death under 808 nm laser irradiation (8 W cm-2, 4 min). For photothermal heating using 730 nm laser, 70% of HeLa cells were killed after 4 min irradiation at a relative low power density of 6 W cm-2. These results demonstrated that the porous Pd nanostructure is an attractive photothermal agent for cancer therapy.Nanoparticle (NP) mediated photothermal effect shows great potential as a noninvasive method for cancer therapy treatment, but the development of photothermal agents with high photothermal conversion efficiency, small size and good biocompatibility is still a big challenge. Herein, we report Pd NPs with a porous structure exhibiting enhanced near infrared (NIR) absorption as compared to Pd nanocubes with a similar size (almost two-fold enhancement with a molar extinction coefficient of 6.3 × 107 M-1 cm-1), and the porous Pd NPs display monotonically rising absorbance from NIR to UV-Vis region. When dispersed in water

  1. Solar gravitational deflection of radio waves measured by very-long-baseline interferometry

    NASA Technical Reports Server (NTRS)

    Counselman, C. C., III; Kent, S. M.; Knight, C. A.; Shapiro, I. I.; Clark, T. A.; Hinteregger, H. F.; Rogers, A. E. E.; Whitney, A. R.

    1974-01-01

    Utilizing a four-antenna technique, simultaneous observations were made, at each end of an 845-km baseline, of the radio sources 3C279 and 3C273B, which are 10 deg apart in the sky. Differences in interferometric phases at 3.7-cm wavelength monitored near the time of the 1972 occultation of 3C279 by the sun, yielded a gravitational deflection of 0.99 plus or minus 0.03 times the value predicted by general relativity, corresponding to gamma = 0.98 plus or minus 0.06 (standard error).

  2. Noncontacting devices to indicate deflection and vibration of turbopump internal rotating parts

    NASA Technical Reports Server (NTRS)

    Hamilton, D. B.; Ensminger, D.; Grieser, D. R.; Plummer, A. M.; Saccocio, E. J.; Kissel, J. W.

    1973-01-01

    The research is reported which was conducted to develop devices for measuring vibrations and deflections of parts, such as impellers, shafts, turbine wheels, and inducers in operating turbopumps. Three devices were developed to the breadboard stage: ultrasonic Doppler transducer, flash X-rays, and light-pipe reflectance. It was found that the X-ray technique is applicable to the shaft assembly and the turbine seal of the J-2 pump, and the light-pipe-reflectance device appears to be ideal for cryogenic pump sections.

  3. Photothermal Property of Metal Nanoparticles and its Application in Polymer Processing

    NASA Astrophysics Data System (ADS)

    Maity, Somsubhra

    The surface plasmon resonance of metal nanoparticles is responsible for their unique optical properties. One of those properties is the capability to transform incident light, at the resonance frequency, into heat energy. The heat is dissipated into the surrounding medium thereby causing a rise in the local temperature. In this work, I describe the methods used to generate plasmonic heat in a polymer matrix and the conditions required for thermal processing of polymers via this approach. The goal of this study is to present photothermal heating as an alternative technique to process polymers, and demonstrate the efficacy of the technique to initiate local phase transformation or actuation or enhance mechanical properties. We successfully demonstrate that low intensity resonant light can be used to generate heat within the polymer matrix and even melt polymers with low melting temperatures. In Chapters 2 and 3, I describe the different factors governing the efficient transformation of incident light energy to heat, and the conditions required to processing different polymer types and polymer morphologies. In Chapter 3, I also describe a fluorescence-based temperature-sensing technique which aids in remotely quantifying the heat produced under different conditions. This helps in monitoring the average temperature of the bulk sample in real time. The heating can be greatly manipulated by modifying not just internal factors like concentration and light intensity, but also external conditions such as the surrounding environment. The heating properties of different shapes of nanoparticles are also studied. In Chapter 4-6, I describe the use of cylindrical nanorods to generate heat to alter the polymer matrix. The anisotropic properties of nanorods are exploited to accomplish polarizationdependent annealing of polymer matrices. The fabrication, characterization and selective processing of aligned nanofibrous polymer samples is described in Chapter 4. Fluorescence

  4. Orthogonally interdigitated shielded serpentine travelling wave cathode ray tube deflection structure

    DOEpatents

    Hagen, E.C.; Hudson, C.L.

    1995-07-25

    A new deflection structure which deflects a beam of charged particles, such as an electron beam, includes a serpentine set for transmitting a deflection field, and a shielding frame for housing the serpentine set. The serpentine set includes a vertical serpentine deflection element and a horizontal serpentine deflection element. These deflection elements are identical, and are interdigitatedly and orthogonally disposed relative to each other, for forming a central transmission passage, through which the electron beam passes, and is deflected by the deflection field, so as to minimize drift space signal distortion. The shielding frame includes a plurality of ground blocks, and forms an internal serpentine trough within these ground blocks, for housing the serpentine set. The deflection structure further includes a plurality of feedthrough connectors which are inserted through the shielding frame, and which are electrically connected to the serpentine set. 10 figs.

  5. Orthogonally interdigitated shielded serpentine travelling wave cathod ray tube deflection structure

    SciTech Connect

    Hagen, E.C.; Hudson, C.L.

    1993-10-27

    This invention comprises a new deflection structure which deflects a beam of charged particles, such as an electron beam, includes a serpentine set for transmitting a deflection field, and shielding frame for housing the serpentine set. The serpentine set includes a vertical serpentine deflection element and a horizontal serpentine deflection element. These deflection elements are identical and are interdigitatedly and orthogonally disposed relative to each other, for forming a central transmission passage, through which the electron beam passes and is deflected by the deflection field to minimize drift space signal distortion. The shielding frame includes a plurality of ground blocks and forms an internal serpentine trough within these ground blocks for housing the serpentine set. The deflection structure further includes a plurality of feedthrough connectors which are inserted through the shielding frame and which are electrically connected to the serpentine set.

  6. Layer model for long-term deflection analysis of cracked reinforced concrete bending members

    NASA Astrophysics Data System (ADS)

    Bacinskas, Darius; Kaklauskas, Gintaris; Gribniak, Viktor; Sung, Wen-Pei; Shih, Ming-Hsiang

    2012-05-01

    A numerical technique has been proposed for the long-term deformation analysis of reinforced concrete members subjected to a bending moment. The technique based on the layer approach in a simple and rational way deals with such complex issues as concrete cracking and tension-stiffening as well as creep and shrinkage. The approach uses the material stress-strain relationships for compressive concrete, cracked tensile concrete and steel. Such effects as linear and nonlinear creep, cracking, tension-stiffening as well as the reduction in concrete tension strength due to sustained loading have been taken into account. The shrinkage effect has been modeled by means of adequate actions of axial force and bending moment. A statistical deflection calculation analysis has been carried out for 322 experimental reinforced concrete beams reported in the literature. The comparative analysis of the experimental and the modeling results has shown that the proposed technique has well captured the time-deflection behavior of reinforced concrete flexural members. The results of the predictions by ACI 318 and Eurocode 2 design codes have been also discussed.

  7. Subminiature deflection circuit operates integrated sweep circuits in TV camera

    NASA Technical Reports Server (NTRS)

    Schaff, F. L.

    1967-01-01

    Small magnetic sweep deflection circuits operate a hand-held lunar television camera. They convert timing signals from the synchronizer into waveforms that provide a raster on the vidicon target. Raster size remains constant and linear during wide voltage and temperature fluctuations.

  8. Deflection of Light by Gravity: A Physical Approach.

    ERIC Educational Resources Information Center

    Diamond, Joshua B.

    1982-01-01

    Einstein's equivalence principle relates effects seen by an accelerating observer to those experienced by an observer in a gravitational field, providing an explanation of bending of a light beam by gravity. Because the calculations lead to results one-half the value found experimentally, obtaining the correct light deflection is discussed.…

  9. Damping of unwanted modes in SRF deflecting/crabbing cavities

    SciTech Connect

    Burt, Graeme; Wang, Haipeng

    2014-01-01

    As deflecting and crab cavities do not use the fundamental acceleration mode for their operation, the spectrum of unwanted modes is significantly different from that of accelerating cavities. The fundamental acceleration mode is now unwanted and can cause energy spread in the beam; in addition this mode frequency is often close to or lower than that of the deflecting mode, making it difficult to damp. This is made more complex in some of the compact crab cavities as there small beampipes often attenuate the fields very sharply. In addition in some crab cavities there can be an orthogonal transverse mode similar to the deflecting mode, known as the same order mode. The degeneracy of these modes must be split by polarising the cavity and if the polarisation is not large enough, dampers should be placed at either an electric or magnetic field null of the crabbing mode to effectively damp the unwanted polarisation. Various concepts for dealing with unwanted modes in various SRF deflecting cavities will be reviewed.

  10. Deflection circuit monitors force on object under water

    NASA Technical Reports Server (NTRS)

    Roller, R.; Yaroshuk, N.

    1968-01-01

    Capsule containing samples for radiation testing is guided under through a seal to an exact position within a nuclear reactor. A Linear Variable Differential Transformer /LVDT/ flexplate deflection circuit monitors the force on the capsule as it is positioned within the reactor.

  11. 30 CFR 7.47 - Deflection temperature test.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Deflection temperature test. 7.47 Section 7.47... temperature test. (a) Test procedures. (1) Prepare two samples for testing that measure 5 inches by 1/2 inch... which are 4 inches apart and immersed in a heat transfer medium at a test temperature range of 65...

  12. On guided versus deflected fields in controlled-source electromagnetics

    NASA Astrophysics Data System (ADS)

    Swidinsky, Andrei

    2015-06-01

    The detection of electrically resistive targets in applied geophysics is of interest to the hydrocarbon, mining and geotechnical industries. Elongated thin resistive bodies have been extensively studied in the context of offshore hydrocarbon exploration. Such targets guide electromagnetic fields in a process which superficially resembles seismic refraction. On the other hand, compact resistive bodies deflect current in a process which has more similarities to diffraction and scattering. The response of a real geological structure is a non-trivial combination of these elements-guiding along the target and deflection around its edges. In this note the electromagnetic responses of two end-member models are compared: a resistive layer, which guides the electromagnetic signal, and a resistive cylinder, which deflects the fields. Results show that the response of a finite resistive target tends to saturate at a much lower resistivity than a resistive layer, under identical survey configurations. Furthermore, while the guided electromagnetic fields generated by a buried resistive layer contain both anomalous horizontal and vertical components, the process of electromagnetic deflection from a buried resistive cylinder creates mainly anomalous vertical fields. Finally, the transmitter orientation with respect to the position of a finite body is an important survey parameter: when the distance to the target is much less than the host skin depth, a transmitter pointing towards the resistive cylinder will produce a stronger signal than a transmitter oriented azimuthally with respect to the cylinder surface. The opposite situation is observed when the distance to the target is greater than the host skin depth.

  13. 30 CFR 7.47 - Deflection temperature test.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Deflection temperature test. 7.47 Section 7.47 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR TESTING, EVALUATION, AND APPROVAL OF MINING PRODUCTS TESTING BY APPLICANT OR THIRD PARTY Battery Assemblies § 7.47...

  14. 30 CFR 7.47 - Deflection temperature test.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Deflection temperature test. 7.47 Section 7.47 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR TESTING, EVALUATION, AND APPROVAL OF MINING PRODUCTS TESTING BY APPLICANT OR THIRD PARTY Battery Assemblies § 7.47...

  15. 75 FR 12981 - Eligibility for Commercial Flats Failing Deflection

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-18

    ... May 2009 was published in the Federal Register (74 FR 15380-15384) on April 6, 2009. The final rule included new deflection standards, previously applicable only to automation flats, for all commercial flat... should be eligible for full-service IMb pricing. If automation prices are denied, pieces that...

  16. Focused ion beam induced deflections of freestanding thin films

    NASA Astrophysics Data System (ADS)

    Kim, Y.-R.; Chen, P.; Aziz, M. J.; Branton, D.; Vlassak, J. J.

    2006-11-01

    Prominent deflections are shown to occur in freestanding silicon nitride thin membranes when exposed to a 50keV gallium focused ion beam for ion doses between 1014 and 1017ions/cm2. Atomic force microscope topographs were used to quantify elevations on the irradiated side and corresponding depressions of comparable magnitude on the back side, thus indicating that what at first appeared to be protrusions are actually the result of membrane deflections. The shape in high-stress silicon nitride is remarkably flat-topped and differs from that in low-stress silicon nitride. Ion beam induced biaxial compressive stress generation, which is a known deformation mechanism for other amorphous materials at higher ion energies, is hypothesized to be the origin of the deflection. A continuum mechanical model based on this assumption convincingly reproduces the profiles for both low-stress and high-stress membranes and provides a family of unusual shapes that can be created by deflection of freestanding thin films under beam irradiation.

  17. Laser-tissue photothermal interaction and tissue temperature change

    NASA Astrophysics Data System (ADS)

    Ives, Andrea K.; Chen, Wei R.; Jassemnejad, Baha; Bartels, Kenneth E.; Liu, Hong; Nordquist, John A.; Nordquist, Robert E.

    2000-06-01

    Responses of tissue to laser stimulation are crucial in both disease diagnostics and treatment. In general, when tissue absorbs laser energy photothermal interaction occurs. The most important signature of the photothermal reaction is the tissue temperature change during and after the laser irradiation. Experimentally, the tissue reaction to laser irradiation can be measured by numerous methods including direct temperature measurement and measurement of perfusion change. In this study, a multiple-channel temperature probe was used to measure tissue temperature change during irradiation of lasers with different wavelengths at different power settings. Tissue temperature in chicken breast tissue as well as skin and breast tumor of rats was measured during irradiation of an 805-nm diode laser. The vertical profiles of temperature were obtained using simultaneous measurement at several different locations. The absorption of laser energy by tissue was enhanced by injecting laser-absorbing dye into the tissue. A Nd:YAG laser of 1064-nm wavelength was also used to irradiate turkey breast tissue. Our results showed that both laser penetration ability and photothermal reaction depended on the wavelength of lasers. In the case of 805-nm laser, the temperature increased rapidly only in the region close to the laser source and the thermal equilibrium could be reached within a short time period. The laser absorbing dye drastically enhanced the thermal reaction, resulting in approximately 4-fold temperature increase. On the contrary, the laser beam with 1064-nm wavelength penetrated deeply into tissue and the tissue temperature continued increasing even after a 10-minute laser irradiation.

  18. Porphyrin-based Nanostructure-Dependent Photodynamic and Photothermal Therapies

    NASA Astrophysics Data System (ADS)

    Jin, Cheng S.

    This thesis presents the investigation of nanostructure-dependent phototherapy. We reviewed the liposomal structures for delivery of photosensitizers, and introduced a novel class of phototransducing liposomes called "porphysomes". Porphysomes are self-assembled from high packing density of pyropheophorbide alpha-conjugated phospholipids, resulting in extreme self-quenching of porphyrin fluorescence and comparable optical absorption to gold nanoparticles for high photothermal efficiency. We demonstrated this self-assembly of porphyrin-lipid conjugates converts a singlet oxygen generating mechanism (photodynamic therapy PDT activity) of porphyrin to photothermal mechanism (photothermal therapy PTT activity). The efficacy of porphysome-enhanced PTT was then evaluated on two pre-clinical animal models. We validated porphysome-enabled focal PTT to treat orthotopic prostate cancer using MRI-guided focal laser placement to closely mimic the current clinic procedure. Furthermore, porphysome-enabled fluorescence-guided transbronchial PTT of lung cancer was demonstrated in rabbit orthotopic lung cancer models, which led to the development of an ultra-minimally invasive therapy for early-stage peripheral lung cancer. On the other hand, the nanostructure-mediated conversion of PDT to PTT can be switched back by nanoparticle dissociation. By incorporating folate-conjugated phospholipids into the formulation, porphysomes were internalized into cells rapidly via folate receptor-mediated endocytosis and resulted in efficient disruption of nanostructures, which turned back on the photodynamic activity of densely packed porphyrins, making a closed loop of conversion between PDT and PTT. The multimodal imaging and therapeutic features of porphysome make it ideal for future personalized cancer treatments.

  19. Photothermal method of determining calorific properties of coal

    DOEpatents

    Amer, N.M.

    1983-05-16

    Predetermined amounts of heat are generated within a coal sample by directing pump light pulses of predetermined energy content into a small surface region of the sample. A beam of probe light is directed along the sample surface and deflection of the probe beam from thermally induced changes of index of refraction in the fluid medium adjacent the heated region are detected. Deflection amplitude and the phase lag of the deflection, relative to the initiating pump light pulse, are indicative of the calorific value and the porosity of the sample. The method provides rapid, accurate and nondestructive analysis of the heat producing capabilities of coal samples. In the preferred form, sequences of pump light pulses of increasing durations are directed into the sample at each of a series of minute regions situated along a raster scan path enabling detailed analysis of variations of thermal properties at different areas of the sample and at different depths.

  20. Kapitza thermal resistance studied by high-frequency photothermal radiometry

    NASA Astrophysics Data System (ADS)

    Horny, Nicolas; Chirtoc, Mihai; Fleming, Austin; Hamaoui, Georges; Ban, Heng

    2016-07-01

    Kapitza thermal resistance is determined using high-frequency photothermal radiometry (PTR) extended for modulation up to 10 MHz. Interfaces between 50 nm thick titanium coatings and silicon or stainless steel substrates are studied. In the used configuration, the PTR signal is not sensitive to the thermal conductivity of the film nor to its optical absorption coefficient, thus the Kapitza resistance is directly determined from single thermal parameter fits. Results of thermal resistances show the significant influence of the nature of the substrate, as well as of the presence of free electrons at the interface.

  1. Destructive fat tissue engineering using photodynamic and selective photothermal effects

    NASA Astrophysics Data System (ADS)

    Tuchin, Valery V.; Yanina, Irina Yu.; Simonenko, Georgy V.

    2009-02-01

    Destructive fat tissue engineering could be realized using the optical method, which provides reduction of regional or site-specific accumulations of subcutaneous adipose tissue on the cell level. We hypothesize that light irradiation due to photodynamic and selective photothermal effects may lead to fat cell lypolytic activity (the enhancement of lipolysis of cell triglycerides due to expression of lipase activity and cell release of free fat acids (FFAs) due to temporal cell membrane porosity), and cell delayed killing due to apoptosis caused by the induced fat cell stress and/or limited cell necrosis.

  2. A photothermally responsive nanoprobe for bioimaging based on Edman degradation.

    PubMed

    Liu, Yi; Wang, Zhantong; Zhang, Huimin; Lang, Lixin; Ma, Ying; He, Qianjun; Lu, Nan; Huang, Peng; Liu, Yijing; Song, Jibin; Liu, Zhibo; Gao, Shi; Ma, Qingjie; Kiesewetter, Dale O; Chen, Xiaoyuan

    2016-05-19

    A new type of photothermally responsive nanoprobe based on Edman degradation has been synthesized and characterized. Under irradiation by an 808 nm laser, the heat generated by the gold nanorod core breaks the thiocarbamide structure and releases the fluorescent dye Cy5.5 with increased near-infrared (NIR) fluorescence under mild acidic conditions. This RGD modified nanoprobe is capable of fluorescence imaging of ανβ3 over-expressing U87MG cells in vitro and in vivo. This Edman degradation-based nanoprobe provides a novel strategy to design activatable probes for biomedical imaging and drug/gene delivery. PMID:27149392

  3. Photothermal Superheating of Water with Ion-Implanted Silicon Nanowires

    SciTech Connect

    Roder, Paden B.; Manandhar, Sandeep; Smith, Bennett E.; Zhou, Xuezhe; Shutthanandan, V.; Pauzauskie, Peter J.

    2015-07-21

    Nanoparticle-mediated photothermal (PT) cancer therapy has been a major focus in nanomedicine due to its potential as an effective, non-invasive, and targeted alternative to traditional cancer therapy based on small-molecule pharmaceuticals[1,2]. Gold nanocrystals have been a primary focus of PT research[3], which can be attributed to their size tunability[4], well understood conjugation chemistry[5], and efficient absorption of NIR radiation in the tissue transparency window (800 nm – 1 μm) due to their size-dependent localized surface plasmon resonances[6].

  4. Photoacoustic recovery after photothermal bleaching in living cells

    PubMed Central

    Li, Chiye; Zhang, Chi; Gao, Liang; Garcia-Uribe, Alejandro

    2013-01-01

    Abstract. We present an innovative method, photoacoustic recovery after photothermal bleaching (PRAP), for studying particle dynamics at micron scale via photoacoustic imaging. As an intuitive way to visualize and quantify dynamic processes, PRAP is demonstrated first in a simple phantom study and then in a more complex measurement involving live cells. Compared with the conventional fluorescence-based approach, PRAP provides high signal-to-noise ratio (SNR) imaging with minimal bleaching-induced artifacts during the recovery stage, ideal for monitoring the diffusive and kinetic processes inside a cell. PMID:24089253

  5. Engineering on-chip nanoporous gold material libraries via precision photothermal treatment [Precision Photothermal Annealing of Nanoporous Gold Thin Films for the Microfabrication of a Single-ship Material Libraries

    DOE PAGESBeta

    Chapman, Christopher A. R.; Wang, Ling; Biener, Juergen; Seker, Erkin; Biener, Monika M.; Matthews, Manyalibo J.

    2016-01-01

    Single-chip material libraries of thin films of nanostructured materials are a promising approach for high throughput studies of structure-property relationship in the fields of physics and biology. Nanoporous gold (np-Au), produced by an alloy corrosion process, is a nanostructured material of specific interest in both these fields. One attractive property of np-Au is its self-similar coarsening behavior by thermally induced surface diffusion. However, traditional heat application techniques for the modification of np-Au are bulk processes that cannot be used to generate a library of different pore sizes on a single chip. Laser micromachining offers an attractive solution to this problemmore » by providing a means to apply energy with high spatial and temporal resolution. In our present study we use finite element multiphysics simulations to predict the effects of laser mode (continuous-wave vs. pulsed) and supporting substrate thermal conductivity on the local np-Au film temperatures during photothermal annealing and subsequently investigate the mechanisms by which the np-Au network is coarsening. Our simulations predict that continuous-wave mode laser irradiation on a silicon supporting substrate supports the widest range of morphologies that can be created through the photothermal annealing of thin film np-Au. Using this result we successfully fabricate a single-chip material library consisting of 81 np-Au samples of 9 different morphologies for use in increased throughput material interaction studies.« less

  6. Engineering on-chip nanoporous gold material libraries via precision photothermal treatment [Precision Photothermal Annealing of Nanoporous Gold Thin Films for the Microfabrication of a Single-ship Material Libraries

    SciTech Connect

    Chapman, Christopher A. R.; Wang, Ling; Biener, Juergen; Seker, Erkin; Biener, Monika M.; Matthews, Manyalibo J.

    2016-01-01

    Single-chip material libraries of thin films of nanostructured materials are a promising approach for high throughput studies of structure-property relationship in the fields of physics and biology. Nanoporous gold (np-Au), produced by an alloy corrosion process, is a nanostructured material of specific interest in both these fields. One attractive property of np-Au is its self-similar coarsening behavior by thermally induced surface diffusion. However, traditional heat application techniques for the modification of np-Au are bulk processes that cannot be used to generate a library of different pore sizes on a single chip. Laser micromachining offers an attractive solution to this problem by providing a means to apply energy with high spatial and temporal resolution. In our present study we use finite element multiphysics simulations to predict the effects of laser mode (continuous-wave vs. pulsed) and supporting substrate thermal conductivity on the local np-Au film temperatures during photothermal annealing and subsequently investigate the mechanisms by which the np-Au network is coarsening. Our simulations predict that continuous-wave mode laser irradiation on a silicon supporting substrate supports the widest range of morphologies that can be created through the photothermal annealing of thin film np-Au. Using this result we successfully fabricate a single-chip material library consisting of 81 np-Au samples of 9 different morphologies for use in increased throughput material interaction studies.

  7. Photothermally Activated Pyroelectric Polymer Films for Harvesting of Solar Heat with a Hybrid Energy Cell Structure.

    PubMed

    Park, Teahoon; Na, Jongbeom; Kim, Byeonggwan; Kim, Younghoon; Shin, Haijin; Kim, Eunkyoung

    2015-12-22

    Photothermal effects in poly(3,4-ethylenedioxythiophene)s (PEDOTs) were explored for pyroelectric conversion. A poled ferroelectric film was coated on both sides with PEDOT via solution casting polymerization of EDOT, to give highly conductive and effective photothermal thin films of PEDOT. The PEDOT films not only provided heat source upon light exposure but worked as electrodes for the output energy from the pyroelectric layer in an energy harvester hybridized with a thermoelectric layer. Compared to a bare thermoelectric system under NIR irradiation, the photothermal-pyro-thermoelectric device showed more than 6 times higher thermoelectric output with the additional pyroelectric output. The photothermally driven pyroelectric harvesting film provided a very fast electric output with a high voltage output (Vout) of 15 V. The pyroelectric effect was significant due to the transparent and high photothermal PEDOT film, which could also work as an electrode. A hybrid energy harvester was assembled to enhance photoconversion efficiency (PCE) of a solar cell with a thermoelectric device operated by the photothermally generated heat. The PCE was increased more than 20% under sunlight irradiation (AM 1.5G) utilizing the transmitted light through the photovoltaic cell as a heat source that was converted into pyroelectric and thermoelectric output simultaneously from the high photothermal PEDOT electrodes. Overall, this work provides a dynamic and static hybrid energy cell to harvest solar energy in full spectral range and thermal energy, to allow solar powered switching of an electrochromic display. PMID:26308669

  8. Combinatorial photothermal and immuno cancer therapy using chitosan-coated hollow copper sulfide nanoparticles.

    PubMed

    Guo, Liangran; Yan, Daisy D; Yang, Dongfang; Li, Yajuan; Wang, Xiaodong; Zalewski, Olivia; Yan, Bingfang; Lu, Wei

    2014-06-24

    Near-infrared light-responsive inorganic nanoparticles have been shown to enhance the efficacy of cancer photothermal ablation therapy. However, current nanoparticle-mediated photothermal ablation is more effective in treating local cancer at the primary site than metastatic cancer. Here, we report the design of a near-infrared light-induced transformative nanoparticle platform that combines photothermal ablation with immunotherapy. The design is based on chitosan-coated hollow CuS nanoparticles that assemble the immunoadjuvants oligodeoxynucleotides containing the cytosine-guanine (CpG) motifs. Interestingly, these structures break down after laser excitation, reassemble, and transform into polymer complexes that improve tumor retention of the immunotherapy. In this "photothermal immunotherapy" approach, photothermal ablation-induced tumor cell death reduces tumor growth and releases tumor antigens into the surrounding milieu, while the immunoadjuvants potentiate host antitumor immunity. Our results indicated that combined photothermal immunotherapy is more effective than either immunotherapy or photothermal therapy alone against primary treated and distant untreated tumors in a mouse breast cancer model. These hollow CuS nanoparticles are biodegradable and can be eliminated from the body after laser excitation. PMID:24801008

  9. Combinatorial Photothermal and Immuno Cancer Therapy Using Chitosan-Coated Hollow Copper Sulfide Nanoparticles

    PubMed Central

    2015-01-01

    Near-infrared light-responsive inorganic nanoparticles have been shown to enhance the efficacy of cancer photothermal ablation therapy. However, current nanoparticle-mediated photothermal ablation is more effective in treating local cancer at the primary site than metastatic cancer. Here, we report the design of a near-infrared light-induced transformative nanoparticle platform that combines photothermal ablation with immunotherapy. The design is based on chitosan-coated hollow CuS nanoparticles that assemble the immunoadjuvants oligodeoxynucleotides containing the cytosine-guanine (CpG) motifs. Interestingly, these structures break down after laser excitation, reassemble, and transform into polymer complexes that improve tumor retention of the immunotherapy. In this “photothermal immunotherapy” approach, photothermal ablation-induced tumor cell death reduces tumor growth and releases tumor antigens into the surrounding milieu, while the immunoadjuvants potentiate host antitumor immunity. Our results indicated that combined photothermal immunotherapy is more effective than either immunotherapy or photothermal therapy alone against primary treated and distant untreated tumors in a mouse breast cancer model. These hollow CuS nanoparticles are biodegradable and can be eliminated from the body after laser excitation. PMID:24801008

  10. Photothermal Monitoring Of Curing Of Polymers

    NASA Technical Reports Server (NTRS)

    Rooney, Michael

    1993-01-01

    Time-resolved infrared radiometry (TRIR) adapted to monitoring curing of some polymers in production. Proposal part of continuing effort to perfect production of hydroxy-terminated polybutadiene for use in liners of solid-fuel rocket motors. Applicable to monitoring changing states of many other materials in process. TRIR, non-contact technique implemented with remotely situated equipment and better suited to use in production.

  11. Dental diagnostic clinical instrument ("Canary") development using photothermal radiometry and modulated luminescence

    NASA Astrophysics Data System (ADS)

    Jeon, R. J.; Sivagurunathan, K.; Garcia, J.; Matvienko, A.; Mandelis, A.; Abrams, S.

    2010-03-01

    Since 1999, our group at the CADIFT, University of Toronto, has developed the application of Frequency Domain Photothermal Radiometry (PTR) and Luminescence (LUM) to dental caries detection. Various cases including artificial caries detection have been studied and some of the inherent advantages of the adaptation of this technique to dental diagnostics in conjunction with modulated luminescence as a dual-probe technique have been reported. Based on these studies, a portable, compact diagnostic instrument for dental clinic use has been designed, assembled and tested. A semiconductor laser, optical fibers, a thermoelectric cooled mid-IR detector, and a USB connected data acquisition card were used. Software lock-in amplifier techniques were developed to compute amplitude and phase of PTR and LUM signals. In order to achieve fast measurement and acceptable signal-to-noise ratio (SNR) for clinical application, swept sine waveforms were used. As a result sampling and stabilization time for each measurement point was reduced to a few seconds. A sophisticated software interface was designed to simultaneously record intra-oral camera images with PTR and LUM responses. Preliminary results using this instrument during clinical trials in a dental clinic showed this instrument could detect early caries both from PTR and LUM signals.

  12. Deflections from two types of Human Surrogates in Oblique Side Impacts

    PubMed Central

    Yoganandan, Narayan; Pintar, Frank A.

    2008-01-01

    The objective of the study was to obtain time-dependent thoracic and abdominal deflections of an anthropomorphic test device, the WorldSID dummy, in oblique impact using sled tests, and compare with post mortem human subject (PMHS) data. To simulate the oblique loading vector, the load wall was configured such that the thorax and abdominal plates were offset by twenty or thirty degrees. Deflections were obtained from a chestband placed at the middle thoracic level and five internal deflection transducers. Data were compared from the chestband and the transducer located at the same level of the thorax. In addition, data were compared with deflections from similar PMHS tests obtained using chestbands placed at the level of the axilla, xyphoid process, and tenth rib, representing the upper thorax, middle thorax, and abdominal region of the biological specimen. Peak deflections ranged from 30 to 85 mm in the dummy tests. Peak deflections ranged from 60 to 115 mm in PMHS. Under both obliquities, dummy deflection-time histories at the location along the chestband in close proximity to the internal deflection transducer demonstrated similar profiles. However, the peak deflection magnitudes from the chestband were approximately 20 mm greater than those from the internal transducer. Acknowledging that the chestband measures external deflections in contrast to the transducer which records internal ribcage deformations, peak deflections match from the two sensors. Deflection time histories were also similar between the dummy and PMHS in terms of morphology, although thoracic deflection magnitudes from the dummy matched more closely with PMHS than abdominal deflection magnitudes. The dummy deformed in such a way that peak deflections occurred along the lateral vector. This was in contrast to PMHS tests wherein maximum deflections occurred along the antero-lateral direction, suggesting differing deformation responses in the two models. In addition, peak deflections occurred

  13. Probing local bias-induced transitions using photothermal excitation contact resonance atomic force microscopy and voltage spectroscopy.

    PubMed

    Li, Qian; Jesse, Stephen; Tselev, Alexander; Collins, Liam; Yu, Pu; Kravchenko, Ivan; Kalinin, Sergei V; Balke, Nina

    2015-02-24

    Nanomechanical properties are closely related to the states of matter, including chemical composition, crystal structure, mesoscopic domain configuration, etc. Investigation of these properties at the nanoscale requires not only static imaging methods, e.g., contact resonance atomic force microscopy (CR-AFM), but also spectroscopic methods capable of revealing their dependence on various external stimuli. Here we demonstrate the voltage spectroscopy of CR-AFM, which was realized by combining photothermal excitation (as opposed to the conventional piezoacoustic excitation method) with the band excitation technique. We applied this spectroscopy to explore local bias-induced phenomena ranging from purely physical to surface electromechanical and electrochemical processes. Our measurements show that the changes in the surface properties associated with these bias-induced transitions can be accurately assessed in a fast and dynamic manner, using resonance frequency as a signature. With many of the advantages offered by photothermal excitation, contact resonance voltage spectroscopy not only is expected to find applications in a broader field of nanoscience but also will provide a basis for future development of other nanoscale elastic spectroscopies. PMID:25559112

  14. Near-Infrared Light-Responsive Hydrogel for Specific Recognition and Photothermal Site-Release of Circulating Tumor Cells.

    PubMed

    Lv, Song-Wei; Liu, Ya; Xie, Min; Wang, Jing; Yan, Xue-Wei; Li, Zhen; Dong, Wei-Guo; Huang, Wei-Hua

    2016-06-28

    Isolation of single circulating tumor cells (CTCs) from patients is a very challenging technique that may promote the process of individualized antitumor therapies. However, there exist few systems capable of highly efficient capture and release of single CTCs with high viability for downstream analysis and culture. Herein, we designed a near-infrared (NIR) light-responsive substrate for highly efficient immunocapture and biocompatible site-release of CTCs by a combination of the photothermal effect of gold nanorods (GNRs) and a thermoresponsive hydrogel. The substrate was fabricated by imprinting target cancer cells on a GNR-pre-embedded gelatin hydrogel. Micro/nanostructures generated by cell imprinting produce artificial receptors for cancer cells to improve capture efficiency. Temperature-responsive gelatin dissolves rapidly at 37 °C; this allows bulk recovery of captured CTCs at physiological temperature or site-specific release of single CTCs by NIR-mediated photothermal activation of embedded GNRs. Furthermore, the system has been applied to capture, individually release, and genetically analyze CTCs from the whole blood of cancer patients. The multifunctional NIR-responsive platform demonstrates excellent performance in capture and site-release of CTCs with high viability, which provides a robust and versatile means toward individualized antitumor therapies and also shows promising potential for dynamically manipulating cell-substrate interactions in vitro. PMID:27299807

  15. Probing local bias-induced transitions using photothermal excitation contact resonance atomic force microscopy and voltage spectroscopy

    SciTech Connect

    Li, Qian; Jesse, Stephen; Tselev, Alexander; Collins, Liam; Yu, Pu; Kravchenko, Ivan; Kalinin, Sergei V.; Balke, Nina

    2015-01-05

    In this paper, nanomechanical properties are closely related to the states of matter, including chemical composition, crystal structure, mesoscopic domain configuration, etc. Investigation of these properties at the nanoscale requires not only static imaging methods, e.g., contact resonance atomic force microscopy (CR-AFM), but also spectroscopic methods capable of revealing their dependence on various external stimuli. Here we demonstrate the voltage spectroscopy of CR-AFM, which was realized by combining photothermal excitation (as opposed to the conventional piezoacoustic excitation method) with the band excitation technique. We applied this spectroscopy to explore local bias-induced phenomena ranging from purely physical to surface electromechanical and electrochemical processes. Our measurements show that the changes in the surface properties associated with these bias-induced transitions can be accurately assessed in a fast and dynamic manner, using resonance frequency as a signature. Finally, with many of the advantages offered by photothermal excitation, contact resonance voltage spectroscopy not only is expected to find applications in a broader field of nanoscience but also will provide a basis for future development of other nanoscale elastic spectroscopies.

  16. Probing local bias-induced transitions using photothermal excitation contact resonance atomic force microscopy and voltage spectroscopy

    DOE PAGESBeta

    Li, Qian; Jesse, Stephen; Tselev, Alexander; Collins, Liam; Yu, Pu; Kravchenko, Ivan; Kalinin, Sergei V.; Balke, Nina

    2015-01-05

    In this paper, nanomechanical properties are closely related to the states of matter, including chemical composition, crystal structure, mesoscopic domain configuration, etc. Investigation of these properties at the nanoscale requires not only static imaging methods, e.g., contact resonance atomic force microscopy (CR-AFM), but also spectroscopic methods capable of revealing their dependence on various external stimuli. Here we demonstrate the voltage spectroscopy of CR-AFM, which was realized by combining photothermal excitation (as opposed to the conventional piezoacoustic excitation method) with the band excitation technique. We applied this spectroscopy to explore local bias-induced phenomena ranging from purely physical to surface electromechanical andmore » electrochemical processes. Our measurements show that the changes in the surface properties associated with these bias-induced transitions can be accurately assessed in a fast and dynamic manner, using resonance frequency as a signature. Finally, with many of the advantages offered by photothermal excitation, contact resonance voltage spectroscopy not only is expected to find applications in a broader field of nanoscience but also will provide a basis for future development of other nanoscale elastic spectroscopies.« less

  17. Precision Photothermal Annealing of Nanoporous Gold Thin Films for the Microfabrication of a Single-chip Material Libraries

    SciTech Connect

    Harris, C. D.; Shen, N.; Rubenchik, A.; Demos, S. G.; Matthews, M. J.

    2015-06-30

    Single-chip material libraries of thin films of nanostructured materials are a promising approach for high throughput studies of structure-property relationship in the fields of physics and biology. Nanoporous gold (np-Au), produced by an alloy corrosion process, is a nanostructured material of specific interest in both these fields. One attractive property of np-Au is its self-similar coarsening behavior by thermally induced surface diffusion. However, traditional heat application techniques for the modification of np-Au are bulk processes that cannot be used to generate a library of different pore sizes on a single chip. Laser micromachining offers an attractive solution to this problem by providing a means to apply energy with high spatial and temporal resolution. In the present study we use finite element multiphysics simulations to predict the effects of laser mode (continuous-wave vs. pulsed) and supporting substrate thermal conductivity on the local np-Au film temperatures during photothermal annealing and subsequently investigate the mechanisms by which the np-Au network is coarsening. Our simulations predict that continuous-wave mode laser irradiation on a silicon supporting substrate supports the widest range of morphologies that can be created through the photothermal annealing of thin film np-Au. Using this result we successfully fabricate a single-chip material library consisting of 81 np-Au samples of 9 different morphologies for use in increased throughput material interaction studies.

  18. Controlled-Release System of Small Molecules Triggered by the Photothermal Effect of Polypyrrole.

    PubMed

    Zhang, Hui; Xiong, Linfeng; Liao, Xiaojuan; Huang, Kun

    2016-01-01

    In this paper, a novel synthesis of polyethylene glycol (PEG)-modified polypyrrole (PPy) nanomaterials is demonstrated by combining reversible addition-fragmentation chain transfer polymerization and oxidative polymerization. Dye molecules with a heat-labile linker are used as a model drug and covalently anchored onto the PEGlated PPy nanomaterials via "click chemistry." The strong absorption of such PPy nanomaterials in the near-infrared region endows the system excellent photothermal effect, which can be used not only as efficient photothermal agents for photothermal therapy but also good controllers of a drug-release system by retro D-A reaction. PMID:26524109

  19. Dual-modality photothermal optical coherence tomography and magnetic-resonance imaging of carbon nanotubes.

    PubMed

    Tucker-Schwartz, Jason M; Hong, Tu; Colvin, Daniel C; Xu, Yaqiong; Skala, Melissa C

    2012-03-01

    We demonstrate polyethylene-glycol-coated single-walled carbon nanotubes (CNTs) as contrast agents for both photothermal optical coherence tomography (OCT) and magnetic-resonance imaging (MRI). Photothermal OCT was accomplished with a spectral domain OCT system with an amplitude-modulated 750 nm pump beam using 10 mW of power, and T(2) MRI was achieved with a 4.7 T animal system. Photothermal OCT and T(2) MRI achieved sensitivities of nanomolar concentrations to CNTs dispersed in amine-terminated polyethylene glycol, thus establishing the potential for dual-modality molecular imaging with CNTs. PMID:22378422

  20. Interface resistance in copper coated carbon determined by frequency dependent photothermal radiometry

    NASA Astrophysics Data System (ADS)

    Kijamnajsuk, P.; Giuliani, F.; Chirtoc, M.; Horny, N.; Gibkes, J.; Chotikaprakhan, S.; Bein, B. K.; Pelzl, J.

    2010-03-01

    The heat transfer in copper-carbon flat model systems was studied by frequency dependent photothermal radiometry. A novel approach which relies on the frequency dependence of the photothermal signal phase and amplitude at intermediate frequencies was introduced to determine the thermal interface resistance between the Cu-film and the substrate. The frequency dependent amplitude and phase of the photothermal signals were analyzed in the frame of a model of a one- dimensional heat flow perpendicular to the film plane. The interface resistance of the investigated CuC-sample with a Ti-bonding layer was found to increase by a factor two on heat treatment.

  1. Depth profiling of photothermal compound concentrations using phase sensitive optical coherence tomography

    PubMed Central

    Guan, Guangying; Reif, Roberto; Huang, Zhihong; Wang, Ruikang K.

    2011-01-01

    A model that describes the concentration of photothermal (light-to-heat converters) compounds as a function of depth in a turbid medium is developed. The system consists of a pump laser (808 nm modulated at 400 Hz), which heats a photothermal compound, and a phase sensitive spectral domain optical coherence tomography system, which detects the changes in the optical path length of the sample induced by the temperature increase. The model is theoretically derived and the coefficients are empirically determined using solid homogeneous gel phantoms. The model is validated by reconstructing the concentration of a photothermal compound in thick single and double layer solid phantoms. PMID:22191920

  2. Combined concurrent nanoshell loaded macrophage-mediated photothermal and photodynamic therapies

    NASA Astrophysics Data System (ADS)

    Hirschberg, Henry; Trinidad, Anthony; Christie, Catherine E.; Peng, Qian; Kwon, Young J.; Madsen, Steen

    2015-02-01

    Macrophages loaded with gold nanoshells (AuNS), that convert near infrared light to heat, can be used as transport vectors for photothermal hyperthermia of tumors. The purpose of this study was to investigate the effects of combined macrophage mediated photothermal therapy (PTT) and PDT on head and neck squamous cell carcinoma (HNSCC). The results provide proof of concept for the use of macrophages as a delivery vector of AuNS for photothermal enhancement of the effects of PDT on squamous cell carcinoma. A significant synergy was demonstrated with combined PDT and PTT compared to each modality applied separately.

  3. Photo-thermal quartz tuning fork excitation for dynamic mode atomic force microscope

    SciTech Connect

    Bontempi, Alexia; Teyssieux, Damien; Thiery, Laurent; Hermelin, Damien; Vairac, Pascal; Friedt, Jean-Michel

    2014-10-13

    A photo-thermal excitation of a Quartz Tuning Fork (QTF) for topographic studies is introduced. The non-invasive photo-thermal excitation presents practical advantages compared to QTF mechanical and electrical excitations, including the absence of the anti-resonance and its associated phase rotation. Comparison between our theoretical model and experiments validate that the optical transduction mechanism is a photo-thermal rather than photo-thermoacoustic phenomenon. Topographic maps in the context of near-field microscopy distance control have been achieved to demonstrate the performance of the system.

  4. Facile preparation of hybrid core-shell nanorods for photothermal and radiation combined therapy.

    PubMed

    Deng, Yaoyao; Li, Erdong; Cheng, Xiaju; Zhu, Jing; Lu, Shuanglong; Ge, Cuicui; Gu, Hongwei; Pan, Yue

    2016-02-11

    The hybrid platinum@iron oxide core-shell nanorods with high biocompatibility were synthesized and applied for combined therapy. These hybrid nanorods exhibit a good photothermal effect on cancer cells upon irradiation with a NIR laser. Furthermore, due to the presence of a high atomic number element (platinum core), the hybrid nanorods show a synergistic effect between photothermal and radiation therapy. Therefore, the as-prepared core-shell nanorods could play an important role in facilitating synergistic therapy between photothermal and radiation therapy to achieve better therapeutic efficacy. PMID:26818657

  5. Photothermal ablation of cancer cells using self-doped polyaniline nanoparticles

    NASA Astrophysics Data System (ADS)

    Hong, Yoochan; Cho, Wonseok; Kim, Jeonghun; Hwng, Seungyeon; Lee, Eugene; Heo, Dan; Ku, Minhee; Suh, Jin-Suck; Yang, Jaemoon; Kim, Jung Hyun

    2016-05-01

    Water-stable confined self-doping polyaniline nanocomplexes are successfully fabricated by nano-assembly using lauric acid both as a stabilizer and as a localized dopant. In particular, the colloidal stability of the polyaniline nanocomplexes in neutral pH and the photothermal potential by near-infrared light irradiation are characterized. We demonstrate that confined self-doping polyaniline nanocomplexes as a photothermal nanoagent are preserved in the doped state even at a neutral pH. Finally, confined self-doping polyaniline nanocomplexes aided by lauric acid are successfully applied for the photothermal ablation of cancer cells.

  6. Photothermal ablation of cancer cells using self-doped polyaniline nanoparticles.

    PubMed

    Hong, Yoochan; Cho, Wonseok; Kim, Jeonghun; Hwng, Seungyeon; Lee, Eugene; Heo, Dan; Ku, Minhee; Suh, Jin-Suck; Yang, Jaemoon; Kim, Jung Hyun

    2016-05-01

    Water-stable confined self-doping polyaniline nanocomplexes are successfully fabricated by nano-assembly using lauric acid both as a stabilizer and as a localized dopant. In particular, the colloidal stability of the polyaniline nanocomplexes in neutral pH and the photothermal potential by near-infrared light irradiation are characterized. We demonstrate that confined self-doping polyaniline nanocomplexes as a photothermal nanoagent are preserved in the doped state even at a neutral pH. Finally, confined self-doping polyaniline nanocomplexes aided by lauric acid are successfully applied for the photothermal ablation of cancer cells. PMID:27010331

  7. Performance comparison of background-oriented schlieren and fringe deflection in temperature measurement, part 2: experimental evaluation

    NASA Astrophysics Data System (ADS)

    Blanco, Alan; Barrientos, Bernardino; Mares, Carlos

    2016-06-01

    In part 1 of the study, background-oriented schlieren (BOS) and fringe deflection (FD) were numerically compared when used for the measurement of temperature. The aim of this part is to experimentally corroborate the obtained numerical results. In this regard, we analyze an axisymmetric flame issued by a gas nozzle. Fringe deflection and BOS images are recorded at two different points in time and the corresponding displacement results are compared. Furthermore, we implement a variation of the techniques that allows us to carry out simultaneous displacement measurements by them. In this case, the signals of the techniques are encoded on the RGB channels of a color background image. The results confirm that FD slightly outperforms BOS, in particular for images that contain relatively high temperature gradients or regions with low contrast.

  8. Photothermal nanoblade for large cargo delivery into mammalian cells

    PubMed Central

    Wu, Ting-Hsiang; Teslaa, Tara; Kalim, Sheraz; French, Christopher T.; Maghadam, Shahriar; Wall, Randolph; Miller, Jeffery F.; Witte, Owen N.; Teitell, Michael A.; Chiou, Pei-Yu

    2011-01-01

    It is difficult to achieve controlled cutting of elastic, mechanically fragile, and rapidly resealing mammalian cell membranes. Here, we report a photothermal nanoblade that utilizes a metallic nanostructure to harvest short laser pulse energy and convert it into a highly localized explosive vapor bubble, which rapidly punctures a lightly-contacting cell membrane via high-speed fluidic flows and induced transient shear stress. The cavitation bubble pattern is controlled by the metallic structure configuration and laser pulse duration and energy. Integrating the metallic nanostructure with a micropipette, the nanoblade generates a micron-sized membrane access port for delivering highly concentrated cargo (5×108 live bacteria/ml) with high efficiency (46%) and cell viability (>90%) into mammalian cells. Additional biologic and inanimate cargo over 3-orders of magnitude in size including DNA, RNA, 200 nm polystyrene beads to 2 μm bacteria have also been delivered into multiple mammalian cell types. Overall, the photothermal nanoblade is a new approach for delivering difficult to transfer cargo into mammalian cells. PMID:21247066

  9. Nonlinear photothermal Mid-Infrared Microspectroscopy with Superresolution

    NASA Astrophysics Data System (ADS)

    Erramilli, Shyamsunder; Mertiri, Alket; Liu, Hui; Totachawattana, Atcha; Hong, Mi; Sander, Michelle

    2015-03-01

    We describe a nonlinear method for breaking the diffraction limit in mid-infrared microscopy using nonlinear photothermal microspectroscopy. A Quantum Cascade Laser (QCL) tuned to an infrared active vibrational molecular normal mode is used as the pump laser. A low-phase noise Erbium-doped fiber (EDFL) laser is used as the probe. When the incident intensity of the mid-infrared pump laser is increased past a critical threshold, a nanobubble is nucleated, strongly modulating the scatter of the probe beam, in agreement with prior work. Remarkably, we have also found that the photothermal spectral signature of the mid-infrared absorption bifurcates and is strongly narrowed, consistent with an effective ``mean-field'' theory of the observed pitchfork bifurcation. This ultrasharp narrowing can be exploited to obtain mid-infrared images with a resolution that breaks the diffraction limit, without the need of mechanical scanning near-field probes. The method provides a powerful new tool for hyperspectral label-free mid-infrared imaging and characterization of biological tissues and materials science and engineering. We thank our collaborators H. Altug, L. D. Ziegler, J. Mertz, for their advice and generous loan of equipment.

  10. Laser photothermal therapy in treatment of mouse melanoma

    NASA Astrophysics Data System (ADS)

    Chen, Wei R.; Andrienko, Kirill; Bartels, Kenneth E.; Martin, Steven D.; Liu, Hong; Nordquist, Robert E.

    2005-04-01

    Laser photophysical interactions have been used in treatment of cancers. The use of laser energy provides high target selectivity. With photosensitizers and immunoadjuvants, laser treatment can also provide long-term and systemic effects. Photothermal interaction using an 805-nm diode laser was used to treat metastatic melanoma in mice. B16 tumor cells were implanted subcutaneously in mice. When the tumors reached a size of 0.2 to 0.5 cm3, laser energy was applied to the tumors. The temperature increases was measured using temperature probes. In addition, glycated chitosan (GC), an experimental immunoadjuvant, was also used in combination with the laser treatment. Our experimental results showed that the photothermal interaction could reduce the tumor burdens immediately after the treatment. When GC was used, the survival rates were significantly increased. GC was also applied at different time frames in relation to the laser treatment: 24 hours before, at the same time, and 24 hours after. Our results indicated that when GC was applied 24 hours before the laser treatment, the positive responses of the tumor-bearing animals is higher than that of the other groups. It may be due to the fact that the use of GC can facilitate the immunological stimulation and enhance the treatment of laser.

  11. A photothermally responsive nanoprobe for bioimaging based on Edman degradation

    NASA Astrophysics Data System (ADS)

    Liu, Yi; Wang, Zhantong; Zhang, Huimin; Lang, Lixin; Ma, Ying; He, Qianjun; Lu, Nan; Huang, Peng; Liu, Yijing; Song, Jibin; Liu, Zhibo; Gao, Shi; Ma, Qingjie; Kiesewetter, Dale O.; Chen, Xiaoyuan

    2016-05-01

    A new type of photothermally responsive nanoprobe based on Edman degradation has been synthesized and characterized. Under irradiation by an 808 nm laser, the heat generated by the gold nanorod core breaks the thiocarbamide structure and releases the fluorescent dye Cy5.5 with increased near-infrared (NIR) fluorescence under mild acidic conditions. This RGD modified nanoprobe is capable of fluorescence imaging of ανβ3 over-expressing U87MG cells in vitro and in vivo. This Edman degradation-based nanoprobe provides a novel strategy to design activatable probes for biomedical imaging and drug/gene delivery.A new type of photothermally responsive nanoprobe based on Edman degradation has been synthesized and characterized. Under irradiation by an 808 nm laser, the heat generated by the gold nanorod core breaks the thiocarbamide structure and releases the fluorescent dye Cy5.5 with increased near-infrared (NIR) fluorescence under mild acidic conditions. This RGD modified nanoprobe is capable of fluorescence imaging of ανβ3 over-expressing U87MG cells in vitro and in vivo. This Edman degradation-based nanoprobe provides a novel strategy to design activatable probes for biomedical imaging and drug/gene delivery. Electronic supplementary information (ESI) available: HPLC, MS and 1H NMR spectrum. See DOI: 10.1039/c6nr01400c

  12. Laser photothermal radiometric instrument for industrial steel hardness inspection

    NASA Astrophysics Data System (ADS)

    Guo, X.; Sivagurunathan, K.; Pawlak, M.; Garcia, J.; Mandelis, A.; Giunta, S.; Milletari, S.; Bawa, S.

    2010-03-01

    To meet the industrial demand for on-line steel hardness inspection and quality control, a non-contact, non-destructive laser photothermal radiometric instrument (HD-PTR) was developed. The instrument is equipped with a non-liquid-nitrogen-cooled HgCdZnTe (MCZT) detector, a National Instruments data acquisition card with a Dynamic System Analysis (DSA) module, and control software. A series of industrial steel samples which included automotive screws and aircraft gears (flat or curvilinear) were examined. The effective hardness case depths of these samples ranged from 0.21 mm to 1.78 mm. The results demonstrated that three measurement parameters (metrics) can be extracted when using a fast swept-sine photothermal method. These parameters include the phase minimum (or peak) frequency, fmin, the half width, W, and the area, S. It was found that they are complementary for evaluating widely different ranges of hardness case depths. fminis most suitable for large case depths, and W and S for shallower case depths.

  13. Photothermal transfer function of dielectric mirrors for precision measurements

    NASA Astrophysics Data System (ADS)

    Ballmer, Stefan W.

    2015-01-01

    The photothermal transfer function from absorbed power incident on a dielectric mirror to the effective mirror position is calculated using the coating design as input. The effect is found to change in amplitude and sign for frequencies corresponding to diffusion length comparable to the coating thickness. Transfer functions are calculated for the T i -doped Ta2O5:SiO2 coating used in Advanced LIGO and for a crystalline AlxGa1 -xAs coating. The shape of the transfer function at high frequencies is shown to be a sensitive indicator of the effective absorption depth, providing a potentially powerful tool to distinguish coating-internal absorption from surface contamination related absorption. The sign change of the photothermal effect could also be useful to stabilize radiation pressure-based optomechanical systems. High frequency corrections to the previously published thermo-optic noise estimates are also provided. Finally, estimating the quality of the thermo-optic noise cancellation occurring in fine-tuned AlxGa1 -xAs coatings requires the detailed heat flow analysis done in this paper.

  14. Laser activated nanothermolysis of leukemia cells monitored by photothermal microscopy

    NASA Astrophysics Data System (ADS)

    Lapotko, Dmitri; Lukianova, Ekaterina; Shnip, Alexander; Zheltov, George; Potapnev, Michail; Savitsky, Valeriy; Klimovich, Olga; Oraevsky, Alexander

    2005-04-01

    We are developing new diagnostic and therapeutic technologies for leukemia based on selective targeting of leukemia cells with gold nanoparticles and thermomechanical destruction of the tumor cells with laser-induced microbubbles. Clusters of spherical gold nanoparticles that have strong optical absorption of laser pulses at 532 nm served as nucleation sites of vapor microbubbles. The nanoparticles were targeted selectively to leukemia cells using leukemia-specific surface receptors and a set of two monoclonal antibodies. Application of a primary myeloid-specific antibody to tumor cells followed by targeting the cells with 30-nm nanoparticles conjugated with a secondary antibody (IgG) resulted in formation of nanoparticulate clusters due to aggregation of IgGs. Formation of clusters resulted in substantial decrease of the damage threshold for target cells. The results encourage development of Laser Activated Nanothermolysis as a Cell Elimination Therapy (LANCET) for leukemia. The proposed technology can be applied separately or in combination with chemotherapy for killing leukemia cells without damage to other blood cells. Potential applications include initial reduction of concentration of leukemia cells in blood prior to chemotherapy and treatment of residual tumor cells after the chemotherapy. Laser-induced bubbles in individual cells and cell damage were monitored by analyzing profile of photothermal response signals over the entire cell after irradiation with a single 10-ns long laser pulse. Photothermal microscopy was utilized for imaging formation of microbubbles around nanoparticulate clusters.

  15. Sensitivity analysis for large-deflection and postbuckling responses on distributed-memory computers

    NASA Technical Reports Server (NTRS)

    Watson, Brian C.; Noor, Ahmed K.

    1995-01-01

    A computational strategy is presented for calculating sensitivity coefficients for the nonlinear large-deflection and postbuckling responses of laminated composite structures on distributed-memory parallel computers. The strategy is applicable to any message-passing distributed computational environment. The key elements of the proposed strategy are: (1) a multiple-parameter reduced basis technique; (2) a parallel sparse equation solver based on a nested dissection (or multilevel substructuring) node ordering scheme; and (3) a multilevel parallel procedure for evaluating hierarchical sensitivity coefficients. The hierarchical sensitivity coefficients measure the sensitivity of the composite structure response to variations in three sets of interrelated parameters; namely, laminate, layer and micromechanical (fiber, matrix, and interface/interphase) parameters. The effectiveness of the strategy is assessed by performing hierarchical sensitivity analysis for the large-deflection and postbuckling responses of stiffened composite panels with cutouts on three distributed-memory computers. The panels are subjected to combined mechanical and thermal loads. The numerical studies presented demonstrate the advantages of the reduced basis technique for hierarchical sensitivity analysis on distributed-memory machines.

  16. Monte Carlo and Analytical Calculation of Lateral Deflection of Proton Beams in Homogeneous Targets

    NASA Astrophysics Data System (ADS)

    Pazianotto, Maurício T.; Inocente, Guilherme F.; da Silva, Danilo Anacleto A.; Hormaza, Joel M.

    2010-05-01

    Proton radiation therapy is a precise form of radiation therapy, but the avoidance of damage to critical normal tissues and the prevention of geographical tumor misses require accurate knowledge of the dose delivered to the patient and the verification of his position demand a precise imaging technique. In proton therapy facilities, the X-ray Computed Tomography (xCT) is the preferred technique for the planning treatment of patients. This situation has been changing nowadays with the development of proton accelerators for health care and the increase in the number of treated patients. In fact, protons could be more efficient than xCT for this task. One essential difficulty in pCT image reconstruction systems came from the scattering of the protons inside the target due to the numerous small-angle deflections by nuclear Coulomb fields. The purpose of this study is the comparison of an analytical formulation for the determination of beam lateral deflection, based on Molière's theory and Rutherford scattering with Monte Carlo calculations by SRIM 2008 and MCNPX codes.

  17. A beam deflection apparatus with high resolution for monitoring TGS crystal growth

    SciTech Connect

    Musazzi, S.; Affinito, A.; Stenzel, C.; Fabritius, G.

    1996-12-31

    A beam deflection apparatus with a high resolution has been developed which allows monitoring of temperature and concentration gradients in the region around a TGS (triglycine sulphate) crystal growing from an aqueous solution. The developed optical setup consists of two measuring arms that allow inspection of the test region along two perpendicular directions. With a lateral position sensing device the deflection of a mildly focused laser beam traversing the medium to be tested have been measured along one inspection axis, while a two-dimensional analysis of the test region is performed in the orthogonal direction by means of a properly focused light blade and a CCD camera. Experimental verification of the technique has been performed utilizing TGS crystal growth by means of the cooled sting method. The experiment takes place in a double-wall glass cell, the temperature of the TGS crystal can be adjusted independently from the solution temperature. Systematic measurements have been performed which allow to characterize concentration gradients and thermal convection in the vicinity of the crystal. Analysis of experimental results shows the high sensitivity of this method. This technique is well suited as a diagnostic tool for monitoring and controlling crystal growth experiments in microgravity.

  18. Monte Carlo and Analytical Calculation of Lateral Deflection of Proton Beams in Homogeneous Targets

    SciTech Connect

    Pazianotto, Mauricio T.; Inocente, Guilherme F.; Silva, Danilo Anacleto A. d; Hormaza, Joel M.

    2010-05-21

    Proton radiation therapy is a precise form of radiation therapy, but the avoidance of damage to critical normal tissues and the prevention of geographical tumor misses require accurate knowledge of the dose delivered to the patient and the verification of his position demand a precise imaging technique. In proton therapy facilities, the X-ray Computed Tomography (xCT) is the preferred technique for the planning treatment of patients. This situation has been changing nowadays with the development of proton accelerators for health care and the increase in the number of treated patients. In fact, protons could be more efficient than xCT for this task. One essential difficulty in pCT image reconstruction systems came from the scattering of the protons inside the target due to the numerous small-angle deflections by nuclear Coulomb fields. The purpose of this study is the comparison of an analytical formulation for the determination of beam lateral deflection, based on Moliere's theory and Rutherford scattering with Monte Carlo calculations by SRIM 2008 and MCNPX codes.

  19. Understanding the photothermal heating effect in non-lamellar liquid crystalline systems, and the design of new mixed lipid systems for photothermal on-demand drug delivery.

    PubMed

    Fong, Wye-Khay; Hanley, Tracey L; Thierry, Benjamin; Tilley, Adam; Kirby, Nigel; Waddington, Lynne J; Boyd, Ben J

    2014-12-01

    Lipid-based liquid crystalline systems are showing potential as stimuli-responsive nanomaterials, and NIR-responsive gold nanoparticles have been demonstrated to provide control of transitions in non-lamellar phases. In this study, we focus on a deeper understanding of the photothermal response of both lamellar and non-lamellar phases, and new systems formed by alternative lipid systems not previously reported, by linking the photothermal heating to the bulk thermal properties of the materials. Dynamic photothermal studies were performed using NIR laser irradiation and monitoring the structural response using time resolved small angle X-ray scattering for the bulk phases and hexosomes. In addition, cryoFESEM and cryoTEM were used to visualise and assess the effect of GNR incorporation into hexagonal phase nanostructures. The ability of the systems to respond to photothermal heating was correlated with the thermal phase behaviour and heat capacities of the different structures. Access to alternative phase transitions in these systems and understanding the likely photothermal response will facilitate different modes of application of these hybrid nanomaterials for on-demand drug delivery applications. PMID:25325902

  20. Ultra large deflection of thin PZT/aluminium cantilever beam

    NASA Astrophysics Data System (ADS)

    Seveno, Raynald; Guiffard, Benoit; Regoin, Jean-Pierre

    2015-04-01

    Flexible piezoelectric cantilever beam has been realized by depositing lead zirconate titanate (PZT) thin film (4.5 μm) by chemical solution deposition (CSD) onto very thin aluminium foil (16 μm). The tip deflection of the beam has been measured as a function of the frequency of the applied sinusoidal voltage to the PZT film for different amplitudes. Resonance curves have been compared to a classical model of an oscillating system under sinusoidal stress with a very good agreement. Despite of weak ferroelectric properties (remnant polarization: 13 μC/cm2), ultra-large deflection amplitudes have been measured under very moderate applied voltage values: 750 μm@10 V for quasi-static mode and 5 mm@10 V at the resonance frequency ( 12 Hz), which makes this PZT/aluminium composite film very promising for highly flexible actuation applications where large displacements are wanted.