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Sample records for impedance spectroscopic studies

  1. Dielectric and impedance spectroscopic studies of neodymium gallate

    NASA Astrophysics Data System (ADS)

    Sakhya, Anup Pradhan; Dutta, Alo; Sinha, T. P.

    2016-05-01

    The AC electrical properties of a polycrystalline neodymium gallate, NdGaO3 (NGO), synthesized by the sol-gel method have been investigated by employing impedance spectroscopy in the frequency range from 42 Hz to 5 MHz and in the temperature range from 323 K to 593 K. The X-ray diffraction analysis shows that the compound crystallizes in the orthorhombic phase with Pbnm space group at room temperature. Two relaxation processes with different relaxation times are observed from the impedance as well as modulus spectroscopic measurements, which have been attributed to the grain and the grain boundary effects at different temperatures in NGO. The complex impedance data are analyzed by an electrical equivalent circuit consisting of a resistance and a constant phase element in parallel. It has been observed that the value of the capacitance and the resistance associated with the grain boundary is higher than those associated with the grain. The temperature dependent electrical conductivity shows the negative temperature coefficient of resistance. The frequency dependent conductivity spectra are found to follow the power law.

  2. Impedance and modulus spectroscopic study of nano hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Jogiya, B. V.; Jethava, H. O.; Tank, K. P.; Raviya, V. R.; Joshi, M. J.

    2016-05-01

    Hydroxyapatite (Ca10 (PO4)6 (OH)2, HAP) is the main inorganic component of the hard tissues in bones and also important material for orthopedic and dental implant applications. Nano HAP is of great interest due to its various bio-medical applications. In the present work the nano HAP was synthesized by using surfactant mediated approach. Structure and morphology of the synthesized nano HAP was examined by the Powder XRD and TEM. Impedance study was carried out on pelletized sample in a frequency range of 100Hz to 20MHz at room temperature. The variation of dielectric constant, dielectric loss, and a.c. conductivity with frequency of applied field was studied. The Nyquist plot as well as modulus plot was drawn. The Nyquist plot showed two semicircle arcs, which indicated the presence of grain and grain boundary effect in the sample. The typical behavior of the Nyquist plot was represented by equivalent circuit having two parallel RC combinations in series.

  3. Memory-switching phenomenon in acceptor-rich organic molecules: impedance spectroscopic studies.

    PubMed

    Bandyopadhyay, Anirban; Pal, Amlan J

    2005-04-01

    We have studied memory-switching phenomena in terms of impedance spectroscopy in a series of xanthene-class fluorescein molecules. Frequency response studies have revealed that the electronic conduction mechanism was largely tuned by increasing the number of acceptor groups attached to the molecular backbone. In molecules with weak intermolecular interactions, the transition between a low- and a high-conducting state has been associated with a change in bulk resistance and dielectric properties. The devices in the two states remained a parallel combination of a resistor and a capacitor (C(P)-R(P)) network. In devices based on Rose Bengal, which exhibits a strong dipole-dipole interaction due to its acceptor groups, the switching between the states has been modeled as a transition between a C(P)-R(P) network in the off-state and a distributed resistor-capacitor (R-C) line network in the on-state. Instead of isolated clusters, a highly coupled network of reduced Rose Bengal molecules with strong dipole-dipole interaction yielded the high-conducting state. Under a "write-read-erase-read" sequence, the device switched between the two networks reversibly for many cycles. PMID:16851669

  4. Surface-modified CAU-10 MOF materials as humidity sensors: impedance spectroscopic study on water uptake.

    PubMed

    Weiss, Alexander; Reimer, Nele; Stock, Norbert; Tiemann, Michael; Wagner, Thorsten

    2015-09-01

    Metal-organic frameworks (MOFs) are crystalline microporous materials with tunable chemical and physical properties. By combining various metal clusters with different interconnecting organic linkers, the pore structure, crystallinity, as well as the surface properties can be modified. In the present work, modification of the organic linker molecules is utilized to synthesize CAU-10 type MOFs with variable affinity of the pore surface to water. In principle, this should influence the accessibility of the pores for water vapor and therefore offer a tool to control its sorption properties. For a deeper understanding we studied the water sorption characteristics and compared the results to the conductive and dielectric properties studied by impedance spectroscopy. Spectra in a wide frequency range from 1 mHz to 1 MHz were recorded. Data analysis is performed using the Havriliak-Negami model. The MOFs are also tested as sensitive layers for capacitive humidity sensing by correlating the change in permittivity of the materials with the amount of physisorbed water. Such an MOF-based sensor was tested with respect to environmental monitoring and compared to a commonly used commercial humidity sensor. PMID:26227316

  5. Alternating current impedance and Raman spectroscopic study on electrochromic a-WO{sub 3} films

    SciTech Connect

    Lee, Se-Hee; Cheong, Hyeonsik M.; Tracy, C. Edwin; Mascarenhas, Angelo; Pitts, J. Roland; Jorgensen, Gary; Deb, Satyen K.

    2000-06-26

    The chemical diffusion of lithium ions in a-Li{sub x}WO{sub 3} films is investigated using alternating current impedance spectroscopy and Raman scattering measurements. The diffusion coefficients increase with increasing x in a-Li{sub x}WO{sub 3} up to x=0.072 and then decrease. Raman measurements show that the W{sup 6+}=O/O-W{sup 6+}-O ratio also increases at the early stage of lithium insertion and then decreases with further lithium insertion. We conclude that the diffusion kinetics of lithium ions in a-Li{sub x}WO{sub 3} films is very closely related to the W{sup 6+}=O/O-W{sup 6+}-O ratio. (c) 2000 American Institute of Physics.

  6. Electrical properties of double perovskite oxide Sr2LaSbO6: An impedance spectroscopic study

    NASA Astrophysics Data System (ADS)

    Dutta, Alo; Kumari, Premlata; Sinha, T. P.

    2015-09-01

    The Rietveld refinement of the room temperature x-ray diffraction pattern of double perovskite oxide, Sr2LaSbO6 (SLS) synthesized by the solid-state reaction technique shows monoclinic phase with P21/ n symmetry, which is substantiated by the Raman spectrum of the sample. The dielectric relaxation of SLS is investigated in the temperature range from 30°C to 300°C and in the frequency range from 50 Hz to 1 MHz. The Cole-Cole model is used to explain the dielectric relaxation of SLS. The most probable relaxation frequencies at various temperatures are found to obey the Arrhenius law with an activation energy of 0.36 eV, which indicates that the polaron hopping plays the main role in the dielectric relaxation of SLS. The complex impedance plane plots are analyzed by an electrical equivalent circuit consisting of a resistance and a constant phase element. The frequency dependent conductivity spectra obey the power law. [Figure not available: see fulltext.

  7. Impedance spectroscopic characterization of gadolinium substituted cobalt ferrite ceramics

    SciTech Connect

    Rahman, Md. T. Ramana, C. V.

    2014-10-28

    Gadolinium (Gd) substituted cobalt ferrites (CoFe{sub 2−x}Gd{sub x}O{sub 4}, referred to CFGO) with variable Gd content (x = 0.0–0.4) have been synthesized by solid state ceramic method. The crystal structure and impedance properties of CFGO compounds have been evaluated. X-ray diffraction measurements indicate that CFGO crystallize in the inverse spinel phase. The CFGO compounds exhibit lattice expansion due to substitution of larger Gd ions into the crystal lattice. Impedance spectroscopy analysis was performed under a wide range of frequency (f = 20 Hz–1 MHz) and temperature (T = 303–573 K). Electrical properties of Gd incorporated Co ferrite ceramics are enhanced compared to pure CoFe{sub 2}O{sub 4} due to the lattice distortion. Impedance spectroscopic analysis illustrates the variation of bulk grain and grain-boundary contributions towards the electrical resistance and capacitance of CFGO materials with temperature. A two-layer heterogeneous model consisting of moderately conducting grain interior (ferrite-phase) regions separated by insulating grain boundaries (resistive-phase) accurately account for the observed temperature and frequency dependent electrical characteristic of CFGO ceramics.

  8. Raman and impedance spectroscopic studies of the specific features of the transport properties of electrolytes based on CeO2

    NASA Astrophysics Data System (ADS)

    Sal'nikov, V. V.; Pikalova, E. Yu.

    2015-10-01

    The solid solutions CeO2-(Sm,Nd)2O3 have been prepared by the solid-phase synthesis. The microstructure, density, and electrical conductivity of ceramic samples obtained by rolling with an organic binder, followed by sintering in air at a temperature of 1600°C have been investigated. The contributions to the total conductivity from the grain volume and grain boundaries in the temperature range of 250-700°C have been separated using impedance spectroscopy. The impedance spectroscopy data have revealed a significant effect of grain boundaries on the transport properties of the solid electrolyte with a Sm dopant as compared to the electrolyte with Nd. The optical properties of the polycrystalline electrolytes Ce1- x Nd x O2-δ and Ce0.8Sm0.2O2-δ have been studied using Raman spectroscopy. In the spectrum of the ceramic samples, there are two modes: a mode of CeO2 at a frequency of 465 cm-1 and an additional mode at a frequency of ~550 cm-1 due to vibrations associated with oxygen vacancies, the intensity of which depends on the dopant concentration and the energy of the dopant cation-oxygen vacancy bond. The binding energy of oxygen vacancies in the fluorite structure correlates with the behavior of bulk conductivity, and the solid solutions with samarium exhibit the highest bulk conductivity.

  9. Dielectric and impedance spectroscopic studies of 0.8BaTiO3-0.2Bi0.5K0.5TiO3 lead-free ceramics

    NASA Astrophysics Data System (ADS)

    Ramesh, M. N. V.; Ramesh, K. V.

    2015-06-01

    0.8BaTiO3-0.2Bi0.5K0.5TiO3 (BT-BKT20) lead-free ceramics were prepared by conventional solid state reaction method followed by high energy ball milling. The formation of a single phase tetragonal structure in the material was confirmed by X-ray diffraction. Frequency and temperature-dependent dielectric studies show relaxor behavior in the BT-BKT20 which was found to obey modified Curie-Weiss law with degree of diffuseness 1.573. Complex impedance and electric modulus spectroscopy studies reveal temperature-dependent relaxation process in the material. The Cole-Cole plots were measured at high temperatures at which grain effect was observed. Impedance and electric modulus spectroscopy studies show non-Debye kind of conductivity relaxation process in the present material. Activation energies were calculated from impedance and electric modulus spectroscopy and the values of activation energy indicated that the conduction is ionic in nature. AC and DC conductivity have been measured and studied at different temperatures.

  10. Study of Body Composition by Impedance Analysis

    NASA Astrophysics Data System (ADS)

    González-Solís, J. L.; Vargas-Luna, M.; Sosa-Aquino, M.; Bernal-Alvarado, J.; Gutiérrez-Juárez, G.; Huerta-Franco, R.; Sanchis-Sabater, A.

    2002-08-01

    This work presents a set of impedance measurements and preliminary results on the analysis of body composition using impedance spectroscopy. This study is made using a pork meat sample and spectra from fat and flesh region were independently obtained using the same electrodes array. From these measurements, and theoretical considerations, it is possible to explain the behavior of the composite sample flesh-fat-flesh and, fitting the electrical parameters of the model, it shows the plausibility of a physical and quantitative application to human corporal composition.

  11. Impedance Spectroscopic Investigation of Proton Conductivity in Nafion Using Transient Electrochemical Atomic Force Microscopy (AFM)

    PubMed Central

    Hink, Steffen; Wagner, Norbert; Bessler, Wolfgang G.; Roduner, Emil

    2012-01-01

    Spatially resolved impedance spectroscopy of a Nafion polyelectrolyte membrane is performed employing a conductive and Pt-coated tip of an atomic force microscope as a point-like contact and electrode. The experiment is conducted by perturbing the system by a rectangular voltage step and measuring the incurred current, followed by Fourier transformation and plotting the impedance against the frequency in a conventional Bode diagram. To test the potential and limitations of this novel method, we present a feasibility study using an identical hydrogen atmosphere at a well-defined relative humidity on both sides of the membrane. It is demonstrated that good quality impedance spectra are obtained in a frequency range of 0.2–1000 Hz. The extracted polarization curves exhibit a maximum current which cannot be explained by typical diffusion effects. Simulation based on equivalent circuits requires a Nernst element for restricted diffusion in the membrane which suggests that this effect is based on the potential dependence of the electrolyte resistance in the high overpotential region. PMID:24958175

  12. Spectroscopic study of sprites

    NASA Astrophysics Data System (ADS)

    Kanmae, Takeshi

    Optical emissions from sprites--large electric discharges in the mesosphere caused by intense lightning strokes--have been studied for decades. Studies have identified that sprite emissions are primarily composed of molecular band emissions of nitrogen and notably identified the near ultraviolet and blue emission from the N2+ First Negative system, which provided direct evidence of ionization in sprites. This implies that further evidence of the ionization may be provided by the visible and near infrared emission from the N2+ Meinel system, which is more accessible from ground-based platforms, though anticipated strong quenching in the mesosphere and below have made the presence of the emission somewhat controversial. To investigate the presence of the Meinel emission along the vertical extent of sprites, we made ground-based spectral observations in 2005. The observed spectra were mainly composed of the N2 First Positive system, and no or little indication of the Meinel bands were found. This study suggests that the quenching is indeed severe at sprite altitude, and it is difficult to study the ionization process in sprites via the Meinel emission. In addition, the data allowed us to investigate details of the First Positive emission from sprites. The observed First Positive spectra showed that the vibrational distribution of the upper state varies along the vertical extent of sprites, which is in agreement with previous reports, and furthermore this study indicates that the variation is associated with altitude, implying that collisional energy transfer processes play roles in exciting the First Positive emission, particularly at lower altitudes. Recent high-speed imaging observations have revealed the very dynamic nature of sprites: they develop within a few to 10 ms in forms of streamers and columnar glows. The underlying electron energies in these features have been inferred from their emissions in previous measurements, but they lacked either sufficient

  13. Nuclear spectroscopic studies

    SciTech Connect

    Bingham, C.R.; Guidry, M.W.; Riedinger, L.L.; Sorensen, S.P.

    1993-02-08

    The Nuclear Physics group at the University of Tennessee, Knoxville is involved in several aspects of heavy-ion physics including both nuclear structure and reaction mechanisms. While our main emphasis is on experimental problems involving heavy-ion accelerators, we have maintained a strong collaboration with several theorists in order to best pursue the physics of our measurements. During the last year we have led several experiments at the Holifield Heavy Ion Research Facility and participated in others at Argonne National Laboratory. Also, we continue to be very active in the collaboration to study ultra-relativistic heavy ion physics utilizing the SPS accelerator at CERN in Geneva, Switzerland and in a RHIC detector R D project. Our experimental work is in four broad areas: (1) the structure of nuclei at high angular momentum, (2) heavy-ion induced transfer reactions, (3) the structure of nuclei far from stability, and (4) ultra-relativistic heavy-ion physics. The results of studies in these particular areas will be described in this document in sections IIA, IIB, IIC, and IID, respectively. Areas (1), (3), and (4) concentrate on the structure of nuclear matter in extreme conditions of rotational motion, imbalance of neutrons and protons, or very high temperature and density. Area (2) pursues the transfer of nucleons to states with high angular momentum, both to learn about their structure and to understand the transfer of particles, energy, and angular momentum in collisions between heavy ions. An important component of our program is the strong emphasis on the theoretical aspects of nuclear structure and reactions.

  14. Impedance spectroscopic characterization of Sm2O3 containing lithium borate glasses.

    PubMed

    Ramteke, D D; Gedam, R S

    2014-12-10

    27.5 Li2O-(72.5-X) B2O3-X Sm2O3 (X=0.5, 1, 1.5 and 2) were prepared by conventional melt quench technique. Impedance spectroscopy (IS) is used to study the electrical properties of these prepared glasses. Modulus formalism is introduced to study relaxation behaviour of these glasses. Scaling model shows the good overlap of data on single master curve which suggests that conduction mechanism in these glasses is compositional dependent. Variation of dielectric constant and dielectric loss with the addition of Sm2O3 and frequency are discussed here. PMID:24929310

  15. Impedance studies on Li-ion cathodes

    SciTech Connect

    NAGASUBRAMANIAN, GANESAN

    2000-04-17

    This paper describes the author's 2- and 3-electrode impedance results of metal oxide cathodes. These results were extracted from impedance data on 18650 Li-ion cells. The impedance results indicate that the ohmic resistance of the cell is very nearly constant with state-of-charge (SOC) and temperature. For example, the ohmic resistance of 18650 Li-ion cells is around 60 m{Omega} for different SOCS (4.1V to 3.0V) and temperatures from 35 C to {minus}20 C. However, the interfacial impedance shows a modest increase with SOC and a huge increase of between 10 and 100 times with decreasing temperature. For example, in the temperature regime (35 C down to {minus}20 C) the overall cell impedance has increased from nearly 200 m{Omega} to 8,000 m{Omega}. Most of the increase in cell impedance comes from the metal oxide cathode/electrolyte interface.

  16. Wakefield and impedance studies of a liner using MAFIA

    NASA Astrophysics Data System (ADS)

    Chou, W.; Barts, T.

    1993-12-01

    The liner is a perforated beam tube which is coaxial with an outer bore tube. The 3D code MAFIA version 3.1 is used to study the wakefields, impedances, and resonances of this structure. The short range wakes and low frequency (below the cutoff) impedances are in agreement with the theoretical model. The long range wakes and high frequency resonances are associated with the distribution of the holes (or slots). The dependence of the impedance on the size, shape, and pattern of the holes (or slots) is studied. The impact of the liner impedance on the SSC impedance budget is discussed.

  17. Corrosion Study Using Electrochemical Impedance Spectroscopy

    NASA Technical Reports Server (NTRS)

    Farooq, Muhammad Umar

    2003-01-01

    Corrosion is a common phenomenon. It is the destructive result of chemical reaction between a metal or metal alloy and its environment. Stainless steel tubing is used at Kennedy Space Center for various supply lines which service the orbiter. The launch pads are also made of stainless steel. The environment at the launch site has very high chloride content due to the proximity to the Atlantic Ocean. Also, during a launch, the exhaust products in the solid rocket boosters include concentrated hydrogen chloride. The purpose of this project was to study various alloys by Electrochemical Impedance Spectroscopy in corrosive environments similar to the launch sites. This report includes data and analysis of the measurements for 304L, 254SMO and AL-6XN in primarily neutral 3.55% NaCl. One set of data for 304L in neutral 3.55%NaCl + 0.1N HCl is also included.

  18. AC impedance study of degradation of porous nickel battery electrodes

    NASA Technical Reports Server (NTRS)

    Lenhart, Stephen J.; Macdonald, D. D.; Pound, B. G.

    1987-01-01

    AC impedance spectra of porous nickel battery electrodes were recorded periodically during charge/discharge cycling in concentrated KOH solution at various temperatures. A transmission line model (TLM) was adopted to represent the impedance of the porous electrodes, and various model parameters were adjusted in a curve fitting routine to reproduce the experimental impedances. Degradation processes were deduced from changes in model parameters with electrode cycling time. In developing the TLM, impedance spectra of planar (nonporous) electrodes were used to represent the pore wall and backing plate interfacial impedances. These data were measured over a range of potentials and temperatures, and an equivalent circuit model was adopted to represent the planar electrode data. Cyclic voltammetry was used to study the characteristics of the oxygen evolution reaction on planar nickel electrodes during charging, since oxygen evolution can affect battery electrode charging efficiency and ultimately electrode cycle life if the overpotential for oxygen evolution is sufficiently low.

  19. Alternating current impedance spectroscopic analysis of biofunctionalized vertically-aligned silica nanospring surface for biosensor applications

    NASA Astrophysics Data System (ADS)

    Timalsina, Yukta P.

    In this dissertation, a process of vertically-aligned (silica) nanosprings (VANS) based biosensor development is presented. Alternating current (AC) impedance spectroscopy has been used to analyze sensor response as a function of saline phosphate (SP) buffer and biological solutions. The sensor is a parallel plate capacitor consisting of two glass substrates coated with indium tin oxide (ITO), where the VANS [or randomly-aligned nanosprings (RANS)] grown on one substrate serve as the dielectric spacer layer. The response of a VANS device as a function of ionic concentration in SP buffer was examined and an equivalent circuit model was developed. The results demonstrated that VANS sensors exhibited greater sensitivity to the changes in SP concentration relative to the ITO sensors, which serve as controls. The biofunctionalized VANS surface via physisorption and the cross-linker method demonstrates the repeatability, specificity, and selectivity of the binding. The physisorption of biotinylated immunoglobulin G (B-IgG) onto the VANS surface simplifies the whole sensing procedure for the detection of glucose oxidase, since the avidin-conjugated glucose oxidase (Av-GOx) can directly be immobilized on the B-IgG. The cross linker method involves the covalent attachment of antibodies onto the functionalized VANS surface via imine bond. The experiments revealed that the VANS sensor response is solely the result of the interaction of target molecule i.e. mouse IgG with the probe layer, i.e. goat antimouse IgG (GalphaM IgG). It was determined that VANS-based sensors exhibit a greater magnitude of change between successive bio-layers relative to the controls above 100 Hz, which indicates that the addition of biomolecules inhibits the diffusion of ions and changes the effective dielectric response of the VANS via biomolecular polarization. The study of ionic transport in nanosprings suggested that conductance follows a scaling law. It was demonstrated that a VANS-based device

  20. A Chicken Tissue Phantom for Studying an Electrical Impedance Tomography (EIT) System Suitable for Clinical Imaging

    NASA Astrophysics Data System (ADS)

    Bera, Tushar Kanti; Nagaraju, J.

    2011-12-01

    The study of practical phantoms is essential for assessing the reconstruction algorithms and instrumentation used in Electrical Impedance Tomography (EIT). Responses of saline phantoms with insulator inhomogeneities differ from the real tissue phantoms in several aspects. Also, it is difficult to reconstruct the actual resistivity of the insulator inhomogeneity in a saline background because of their large resistivity difference. A practical biological phantom consisting of two different materials with low resistivity difference is more suitable for impedance imaging studies. In order to demonstrate this, a chicken tissue phantom was developed to study the resistivity imaging in EIT. A 16-electrode array was placed inside the phantom tank filled with chicken muscle tissue paste and chicken tissue. A 1 mA, 50 kHz sinusoidal current was injected at the phantom boundary and the boundary potentials are measured using opposite current injection protocol. Resistivity images were reconstructed from the boundary data using Electrical Impedance and Diffuse Optical Reconstruction Software (EIDORS) and the reconstruction was evaluated by calculating the contrast parameters of the images. Results show that the resistivity of the chicken fat is successfully reconstructed with a proper background resistivity. Impedance spectroscopic studies show that the chicken tissue phantom can be suitably used to evaluate a multifrequency EIT system.

  1. Potentiostatic and ac impedance studies of the hydrogen electrodes used in Ni/H2 batteries

    NASA Technical Reports Server (NTRS)

    Le Helloco, Jean-Guy; Bojkov, Hristo; Parthasarathy, Arvind; Srinivasan, Supramaniam; Appleby, A. J.

    1992-01-01

    In a study of electrode activity for hydrogen evolution and hydrogen ionization, knowledge of the detailed kinetics and of the surface coverage by adsorbed hydrogen is essential. In the Ni/H2 battery, the hydrogen electrode is subjected to high hydrogen pressure; elucidation of the variation of kinetic parameters with hydrogen pressure is therefore of interest. Potentiostatic and ac impedance spectroscopic techniques were used in the present study. The equivalent circuit of the reaction, the kinetic parameters, and their pressure dependence have been determined.

  2. Spectroscopic Studies of Abell Clusters

    NASA Astrophysics Data System (ADS)

    Way, Michael Joseph

    The objectives of this work are to use spectroscopic techniques to accurately categorize galaxies as either HII region star forming galaxies or as Active Galactic Nuclei powered via a black hole, and to use radial velocities and projected positions of galaxies in clusters to obtain the total cluster mass and its distribution. The masses and distributions compare well to X-ray mass measurements. The commonly used Dressler, A., Thompson, I. & Shectman, S. 1985, ApJ, 288, 481 technique for discriminating between Active Galactic Nuclei and HII region galaxies uses the measurement of the equivalent width of the emission lines (OII) 3727 A, H/beta, and (OIII) 5007 A. High quality spectra from 42 galaxies were taken and it is shown that their method is not capable of distinguishing between Active Galactic Nuclei and HII region galaxies. The emission line flux from H/beta, (OIII) 5007 A, (OI) 6300 A, Hα, (NII) 6583 A, and (SII) 6716+6731 A in combination with the method of Veilleux, S. & Osterbrock, D. E. 1987, ApJS, 63, 295 must be used to accurately distinguish between Active Galactic Nuclei and HII region galaxies. Galaxy radial velocities from spectroscopic data and their projected 2-D positions in clusters are used to obtain robust estimates of the total mass and mass distribution in two clusters. The total mass is calculated using the Virial theorem after removing substructure. The mass distribution is estimated via several robust statistical tests for 1-D, 2-D and 3-D structure. It is shown that the derived mass estimates agree well with those found independently from hot X-ray gas emission in clusters.

  3. EPR and impedance spectroscopic investigations on lithium bismuth borate glasses containing nickel and vanadium ions.

    PubMed

    Yadav, Arti; Khasa, Satish; Hooda, Ashima; Dahiya, Manjeet S; Agarwal, Ashish; Chand, Prem

    2016-03-15

    Glasses having composition 7NiO∙23Li2O∙20Bi2O3∙50B2O3, 7V2O5∙23Li2O∙20Bi2O3∙50B2O3 and x(2NiO∙V2O5)∙(30-x)Li2O∙50B2O3∙20Bi2O3 (with x=0, 2, 5, 7 & 10 mol%) prepared through melt-quench route are explored by analyzing density, impedance spectroscopy and electron paramagnetic resonance (EPR). It is found that both density and molar volume increase with an increase in substitution of 2NiO∙V2O5 in the base glass matrix. Different dielectric parameters viz. dielectric loss (ε), electrical modulus (M), loss tangent (tanδ) etc. are evaluated and their variations with frequency and temperature are analyzed which reveals that these glasses exhibit a non-Debye relaxation behavior. A phenomenal description of the capacitive behavior is obtained by considering the circuitry as a parallel combination of bulk resistance (Rb) and constant phase element (CPE). The conduction mechanism is found to follow Quantum Mechanical Tunneling (QMT) model. Spin Hamiltonian Parameters (SHPs) and covalency rates are calculated from the EPR spectra of vanadyl ion. The observed EPR spectra confirmed that V(4+) ion exists as vanadyl ion in the octahedral coordination with tetragonal compression. PMID:26748341

  4. EPR and impedance spectroscopic investigations on lithium bismuth borate glasses containing nickel and vanadium ions

    NASA Astrophysics Data System (ADS)

    Yadav, Arti; Khasa, Satish; Hooda, Ashima; Dahiya, Manjeet S.; Agarwal, Ashish; Chand, Prem

    2016-03-01

    Glasses having composition 7NiO • 23Li2O • 20Bi2O3 • 50B2O3, 7V2O5 • 23Li2O • 20Bi2O3 • 50B2O3 and x(2NiO • V2O5) • (30 - x)Li2O • 50B2O3 • 20Bi2O3 (with x = 0, 2, 5, 7 & 10 mol%) prepared through melt-quench route are explored by analyzing density, impedance spectroscopy and electron paramagnetic resonance (EPR). It is found that both density and molar volume increase with an increase in substitution of 2NiO • V2O5 in the base glass matrix. Different dielectric parameters viz. dielectric loss (ε), electrical modulus (M), loss tangent (tanδ) etc. are evaluated and their variations with frequency and temperature are analyzed which reveals that these glasses exhibit a non-Debye relaxation behavior. A phenomenal description of the capacitive behavior is obtained by considering the circuitry as a parallel combination of bulk resistance (Rb) and constant phase element (CPE). The conduction mechanism is found to follow Quantum Mechanical Tunneling (QMT) model. Spin Hamiltonian Parameters (SHPs) and covalency rates are calculated from the EPR spectra of vanadyl ion. The observed EPR spectra confirmed that V4 + ion exists as vanadyl ion in the octahedral coordination with tetragonal compression.

  5. Spectroscopic studies of copper enzymes

    SciTech Connect

    Dooley, D.M.; Moog, R.; Zumft, W.; Koenig, S.H.; Scott, R.A.; Cote, C.E.; McGuirl, M.

    1986-05-01

    Several spectroscopic methods, including absorption, circular dichroism (CD), magnetic CD (MCD), X-ray absorption, resonance Raman, EPR, NMR, and quasi-elastic light-scattering spectroscopy, have been used to probe the structures of copper-containing amine oxidases, nitrite reductase, and nitrous oxide reductase. The basic goals are to determine the copper site structure, electronic properties, and to generate structure-reactivity correlations. Collectively, the results on the amine oxidases permit a detailed model for the Cu(II) sites in these enzymes to be constructed that, in turn, rationalizes the ligand-binding chemistry. Resonance Raman spectra of the phenylhydrazine and 2,4-dinitrophenyl-hydrazine derivatives of bovine plasma amine oxidase and models for its organic cofactor, e.g. pyridoxal, methoxatin, are most consistent with methoxatin being the intrinsic cofactor. The structure of the Cu(I) forms of the amine oxidases have been investigated by X-ray absorption spectroscopy (XAS); the copper coordination geometry is significantly different in the oxidized and reduced forms. Some anomalous properties of the amine oxidases in solution are explicable in terms of their reversible aggregation, which the authors have characterized via light scattering. Nitrite and nitrous oxide reductases display several novel spectral properties. The data suggest that new types of copper sites are present.

  6. Experimental study of coupling impedance: Part I longitudinal impedance measurement techniques

    SciTech Connect

    Song, J.J.

    1991-10-22

    Beam coupling impedances for the 7-GeV APS storage ring have been numerically estimated. In order to confirm these calculations, measurements of the coupling impedance of various vacuum components around the main storage ring were done with a coaxial wire method. In this paper, the procedure of the longitudinal impedance measurement techniques will be described. As an example, sections of the Cu beam chamber, the Cu beam + antechambers, and the Al beam + antechambers were used as a device under test (DUT) to obtain the results. The transverse impedance measurements will be described in a separate paper.

  7. Impedance mammograph 3D phantom studies.

    PubMed

    Wtorek, J; Stelter, J; Nowakowski, A

    1999-04-20

    The results obtained using the Technical University of Gdansk Electroimpedance Mammograph (TUGEM) of a 3D phantom study are presented. The TUGEM system is briefly described. The hardware contains the measurement head and DSP-based identification modules controlled by a PC computer. A specially developed reconstruction algorithm, Regulated Correction Frequency Algebraic Reconstruction Technique (RCFART), is used to obtain 3D images. To visualize results, the Advance Visualization System (AVS) is used. It allows a powerful image processing on a fast workstation or on a high-performance computer. Results of three types of 3D conductivity perturbations used in the study (aluminum, Plexiglas, and cucumber) are shown. The relative volumes of perturbations less than 2% of the measurement chamber are easily evidenced. PMID:10372188

  8. Spectroscopic study in Z-pinch discharge

    SciTech Connect

    Garamoon, A.A.; Saudy, A.H.; Shark, W.

    1995-12-31

    The temporal variation of the emitted line intensity has been investigated, and thus an important information about the dynamic ionization stages in the Z-pinch discharge has been studied. Also the electron temperature Te, has been deduced by using a spectroscopic technique.

  9. Studying Young Stars with Large Spectroscopic Surveys

    NASA Astrophysics Data System (ADS)

    Martell, Sarah L.

    2016-01-01

    Galactic archaeology is the study of the history of star formation and chemical evolution in the Milky Way, based on present-day stellar populations. Studies of young stars are a key anchor point for Galactic archaeology, since quantities like the initial mass function and the star formation rate can be studied directly in young clusters and star forming regions. Conversely, massive spectroscopic Galactic archaeology surveys can be used as a data source for young star studies.

  10. NGC 6067: A spectroscopic study

    NASA Astrophysics Data System (ADS)

    Alonso-Santiago, J.; Negueruela, I.; Marco, A.; Dorda, R.

    2015-05-01

    NGC 6067 is a young open cluster in the Norma Cloud. Its age is around 100 Ma. It hosts a large population of evolved stars: 14 luminous red stars (most of which K Ib supergiants and late-G/early-K giants), 6--8 B giants, two A/F supergiants and two Cepheids (F/G supergiants). All this would imply that NGC 6067 represent one of the best laboratories in the Galaxy to study the evolution of intermediate-mass stars. Thackeray et al. (1962, MNRAS 124, 445T) performed the first complete study of this cluster but it has been poorly studied since then. We obtained high resolution echelle spectra (R=48000) using FEROS (Fiber Extended Range Optical Spectrograph) mounted on the ESO 2.2 m telescope at La Silla Observatory (Chile) in May 2011. Here we present preliminary results based on this spectroscopy and the UBV photometry listed in Terndrup & Pinsonneault (2007, ApJ 671, 1640).

  11. Spectroscopic study of Mentha oils

    NASA Astrophysics Data System (ADS)

    Rai, A. K.; Singh, A. K.

    The visible fluorescence and excitation spectra of Mentha oils (Japanese mint oil, peppermint oil and spearmint oil) have been recorded. Different physical constants which are characteristic of the fluorescent molecules have been calculated for all three oils. Results reveal that the same group of organic compounds dominate in the oils of peppermint and spearmint, whereas some different compound is present in Japanese mint oil. It is also found that the fluorescence intensity of these oils is comparable to that of Rhodamine 6G dye in methanol solution. Our studies suggest that Mentha oils may be a useful lasing material in the 450-600 nm wavelength range.

  12. Nuclear spectroscopic studies. Progress report

    SciTech Connect

    Bingham, C.R.; Guidry, M.W.; Riedinger, L.L.; Sorensen, S.P.

    1994-02-18

    The Nuclear Physics group at UTK is involved in heavy-ion physics including both nuclear structure and reaction mechanisms. During the last year experimental work has been in 3 broad areas: structure of nuclei at high angular momentum, structure of nuclei far from stability, and ultra-relativistic heavy-ion physics. Results in these areas are described in this document under: properties of high-spin states, study of low-energy levels of nuclei far from stability, and high-energy heavy-ion physics (PHENIX, etc.). Another important component of the work is theoretical interpretation of experimental results (Joint Institute for Heavy Ion Research).

  13. Nuclear spectroscopic studies. Progress report

    SciTech Connect

    Bingham, C.R.; Guidry, M.W.; Riedinger, L.L.; Sorensen, S.P.

    1993-02-08

    The Nuclear Physics group at the University of Tennessee, Knoxville is involved in several aspects of heavy-ion physics including both nuclear structure and reaction mechanisms. While our main emphasis is on experimental problems involving heavy-ion accelerators, we have maintained a strong collaboration with several theorists in order to best pursue the physics of our measurements. During the last year we have led several experiments at the Holifield Heavy Ion Research Facility and participated in others at Argonne National Laboratory. Also, we continue to be very active in the collaboration to study ultra-relativistic heavy ion physics utilizing the SPS accelerator at CERN in Geneva, Switzerland and in a RHIC detector R&D project. Our experimental work is in four broad areas: (1) the structure of nuclei at high angular momentum, (2) heavy-ion induced transfer reactions, (3) the structure of nuclei far from stability, and (4) ultra-relativistic heavy-ion physics. The results of studies in these particular areas will be described in this document in sections IIA, IIB, IIC, and IID, respectively. Areas (1), (3), and (4) concentrate on the structure of nuclear matter in extreme conditions of rotational motion, imbalance of neutrons and protons, or very high temperature and density. Area (2) pursues the transfer of nucleons to states with high angular momentum, both to learn about their structure and to understand the transfer of particles, energy, and angular momentum in collisions between heavy ions. An important component of our program is the strong emphasis on the theoretical aspects of nuclear structure and reactions.

  14. Spectroscopic studies of the transplutonium elements

    SciTech Connect

    Carnall, W.T.; Conway, J.G.

    1983-01-01

    The challenging opportunity to develop insights into both atomic structure and the effects of bonding in compounds makes the study of actinide spectroscopy a particularly fruitful and exciting area of scientific endeavor. It is also the interpretation of f-element spectra that has stimulated the development of the most sophisticated theoretical modeling attempted for any elements in the periodic table. The unique nature of the spectra and the wealth of fine detail revealed make possible sensitive tests of both physical models and the results of Hartree-Fock type ab initio calculations. This paper focuses on the unique character of heavy actinide spectroscopy. It discusses how it differs from that of the lighter member of the series and what are the special properties that are manifested. Following the introduction, the paper covers the following: (1) the role of systematic studies and the relationships of heavy-actinide spectroscopy to ongoing spectroscopic investigations of the lighter members of the series; (2) atomic (free-ion) spectra which covers the present status of spectroscopic studies with transplutonium elements, and future needs and directions in atomic spectroscopy; (3) the spectra of actinide compounds which covers the present status and future directions of spectroscopic studies with compounds of the transplutonium elements; and other spectroscopies. 1 figure, 2 tables.

  15. Spectroscopic Studies of Classical Cepheids.

    NASA Astrophysics Data System (ADS)

    Gauthier, Robert Paul

    The extent and nature of the distortions of the emergent flux spectrum of cepheids due to the effects of the pulsation as a function of period and amplitude are not clearly understood. A multiphase classification study of a sample of 26 cepheids from the southern hemisphere at the relatively high dispersion of 67(ANGSTROM)/mm has been undertaken and complemented with the recent high quality photometric data for Pel (1976) in order to observe the results of increasing period and amplitude of pulsation on the line spectrum. The original framework of such investigations set up by Struve (1944) and Code (1947) has been enlarged upon principally through the use of modern MK standard supergiant sequences. It has been found that, while the spectrum of weak metal lines (in cepheids with periods less than forty days) can always be found to match that of a non-variable supergiant, anomalies in the strengths of the strong metal lines and Balmer H(delta) and H(gamma) lines increase both in number and intensity with increasing period and amplitude. The consequences of this on the line blanketing of the atmosphere are seen to be significant when comparing the color-spectrum relations of different period bins, indicating the inappropriateness of extending intrinsic color relations established with short period variables to the longer period ones. It has also been found that the effects of the amplitude of the pulsation are more directly felt by the atmosphere near the extrema of the physical displacement as evidenced by the sudden widening of the period-spectrum relation at the mid-descending and mid-rising branch phases. Following the suggestions by Sorvari (1974) that the luminosity sensitive OI 7773(ANGSTROM) triplet is responding to the dynamical effects of the pulsation on the atmosphere, a moderate dispersion (27(ANGSTROM)/mm) study of a small sample of cepheids (4) and supergiant standards has been undertaken. It has been found that the strength of this feature throughout

  16. Spectroscopic study of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Curran, Seamus; Weldon, Declan N.; Blau, Werner J.; Zandbergen, Henny W.; Kastner, J.; Kuzmany, Hans

    1994-11-01

    We present a comprehensive experimental study of the vibrational spectra of nanotubes. There are two main lines observed in the Raman spectrum, one positioned at 1350 cm-1, the D line, and the other at 1580 cm-1, the G line. Both these lines are very similar to those seen with disordered graphite. The disorder induced D line is very weak compared to the G line which is indicative of high crystalline materials. The position and intensity of the D line strongly depends on the energy of the exciting laser. This dispersion effect was also observed for graphitic particles and may be explained by a photoselective resonance process of nanotubes with different sizes. There are two optically active modes in the Infrared spectrum for highly orientated polycrystalline graphite which are the E1u and A2u modes. The E1u mode is positioned at 1587 cm-1 while the A2u mode is positioned at 868 cm-1. The Infrared spectrum of the nanotubes shows both modes although the E1u mode is downshifted to 1575 cm-1.

  17. Potassium polytitanate gas-sensor study by impedance spectroscopy.

    PubMed

    Fedorov, F S; Varezhnikov, A S; Kiselev, I; Kolesnichenko, V V; Burmistrov, I N; Sommer, M; Fuchs, D; Kübel, C; Gorokhovsky, A V; Sysoev, V V

    2015-10-15

    Nanocrystalline potassium polytitanates K2O·nTiO2·mH2O represent a new type of semiconducting compounds which are characterized by a high specific surface that makes them promising for use in gas sensors. In this work, we have studied potassium polytitanate mesoporous nanoparticle agglomerates placed over a SiO2/Si substrate equipped with multiple coplanar electrodes to measure the electrical response to various organic vapors, 1000 ppm of concentration, mixed with air by impedance spectrometry in range of the 10(-2)-10(6) Hz. The recorded impedance data for each sensor segment are associated with RC components of an equivalent circuit which are applied to selectively recognize the test vapors exploiting a "multisensor array" approach. PMID:26515008

  18. Impedance microflow cytometry for viability studies of microorganisms

    NASA Astrophysics Data System (ADS)

    Di Berardino, Marco; Hebeisen, Monika; Hessler, Thomas; Ziswiler, Adrian; Largiadèr, Stephanie; Schade, Grit

    2011-02-01

    Impedance-based Coulter counters and its derivatives are widely used cell analysis tools in many laboratories and use normally DC or low frequency AC to perform these electrical analyses. The emergence of micro-fabrication technologies in the last decade, however, provides a new means of measuring electrical properties of cells. Microfluidic approaches combined with impedance spectroscopy measurements in the radio frequency (RF) range increase sensitivity and information content and thus push single cell analyses beyond simple cell counting and sizing applications towards multiparametric cell characterization. Promising results have been shown already in the fields of cell differentiation and blood analysis. Here we emphasize the potential of this technology by presenting new data obtained from viability studies on microorganisms. Impedance measurements of several yeast and bacteria strains performed at frequencies around 10 MHz enable an easy discrimination between dead and viable cells. Moreover, cytotoxic effects of antibiotics and other reagents, as well as cell starvation can also be monitored easily. Control analyses performed with conventional flow cytometers using various fluorescent dyes (propidium iodide, oxonol) indicate a good correlation and further highlight the capability of this device. The label-free approach makes on the one hand the use of usually expensive fluorochromes obsolete, on the other hand practically eliminates laborious sample preparation procedures. Until now, online cell monitoring was limited to the determination of viable biomass, which provides rather poor information of a cell culture. Impedance microflow cytometry, besides other aspects, proposes a simple solution to these limitations and might become an important tool for bioprocess monitoring applications in the biotech industry.

  19. The platinum microelectrode/Nafion interface - An electrochemical impedance spectroscopic analysis of oxygen reduction kinetics and Nafion characteristics

    NASA Technical Reports Server (NTRS)

    Parthasarathy, Arvind; Dave, Bhasker; Srinivasan, Supramaniam; Appleby, John A.; Martin, Charles R.

    1992-01-01

    The objectives of this study were to use electrochemical impedance spectroscopy (EIS) to study the oxygen-reduction reaction under lower humidification conditions than previously studied. The EIS technique permits the discrimination of electrode kinetics of oxygen reduction, mass transport of O2 in the membrane, and the electrical characteristics of the membrane. Electrode-kinetic parameters for the oxygen-reduction reaction, corrosion current densities for Pt, and double-layer capacitances were calculated. The production of water due to electrochemical reduction of oxygen greatly influenced the EIS response and the electrode kinetics at the Pt/Nafion interface. From the finite-length Warburg behavior, a measure of the diffusion coefficient of oxygen in Nafion and diffusion-layer thickness was obtained. An analysis of the EIS data in the high-frequency domain yielded membrane and interfacial characteristics such as ionic conductivity of the membrane, membrane grain-boundary capacitance and resistance, and uncompensated resistance.

  20. Study of surfactant-skin interactions by skin impedance measurements.

    PubMed

    Lu, Guojin; Moore, David J

    2012-02-01

    The stratum corneum (SC) plays a very critical physiological role as skin barrier in regulating water loss through the skin and protects the body from a wide range of physical and chemical exogenous insults. Surfactant-containing formulations can induce skin damage and irritation owing to surfactant absorption and penetration. It is generally accepted that reduction in skin barrier properties occurs only after surfactants have penetrated/permeated into the skin barrier. To mitigate the harshness of surfactant-based cleansing products, penetration/permeation of surfactants should be reduced. Skin impedance measurements have been taken in vitro on porcine skin using vertical Franz diffusion cells to investigate the impact of surfactants, temperature and pH on skin barrier integrity. These skin impedance results demonstrate excellent correlation with other published methods for assessing skin damage and irritation from different surfactant chemistry, concentration, pH, time of exposure and temperature. This study demonstrates that skin impedance can be utilized as a routine approach to screen surfactant-containing formulations for their propensity to compromise the skin barrier and hence likely lead to skin irritation. PMID:21923733

  1. Vibrational spectroscopic study of fluticasone propionate

    NASA Astrophysics Data System (ADS)

    Ali, H. R. H.; Edwards, H. G. M.; Kendrick, J.; Scowen, I. J.

    2009-03-01

    Fluticasone propionate is a synthetic glucocorticoid with potent anti-inflammatory activity that has been used effectively in the treatment of chronic asthma. The present work reports a vibrational spectroscopic study of fluticasone propionate and gives proposed molecular assignments on the basis of ab initio calculations using BLYP density functional theory with a 6-31G* basis set and vibrational frequencies predicted within the quasi-harmonic approximation. Several spectral features and band intensities are explained. This study generated a library of information that can be employed to aid the process monitoring of fluticasone propionate.

  2. X-ray photoelectron spectroscopic and electrochemical impedance spectroscopic analysis of RuO2-Ta2O5 thick film pH sensors.

    PubMed

    Manjakkal, Libu; Cvejin, Katarina; Kulawik, Jan; Zaraska, Krzysztof; Socha, Robert P; Szwagierczak, Dorota

    2016-08-10

    The paper reports on investigation of the pH sensing mechanism of thick film RuO2-Ta2O5 sensors by using X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). Interdigitated conductimetric pH sensors were screen printed on alumina substrates. The microstructure and elemental composition of the films were examined by scanning electron microscopy and energy dispersive spectroscopy. The XPS studies revealed the presence of Ru ions at different oxidation states and the surface hydroxylation of the sensing layer increasing with increasing pH. The EIS analysis carried out in the frequency range 10 Hz-2 MHz showed that the electrical parameters of the sensitive electrodes in the low frequency range were distinctly dependent on pH. The charge transfer and ionic exchange occurring at metal oxide-solution interface were indicated as processes responsible for the sensing mechanism of thick film RuO2-Ta2O5 pH sensors. PMID:27282750

  3. Impedance spectroscopic analysis of composite electrode from activated carbon/conductive materials/ruthenium oxide for supercapacitor applications

    NASA Astrophysics Data System (ADS)

    Taer, E.; Deraman, M.; Talib, I. A.; Awitdrus, Farma, R.; Ishak, M. M.; Omar, R.; Dolah, B. N. M.; Basri, N. H.; Othman, M. A. R.; Kanwal, S.

    2015-04-01

    Activated carbon powders (ACP) were produced from the KOH treated pre-carbonized rubber wood sawdust. Different conductive materials (graphite, carbon black and carbon nanotubes (CNTs)) were added with a binder (polivinylidene fluoride (PVDF)) into ACP to improve the supercapacitive performance of the activated carbon (AC) electrodes. Symmetric supercapacitor cells, fabricated using these AC electrodes and 1 molar H2SO4 electrolyte, were analyzed using a standard electrochemical impedance spectroscopy technique. The addition of graphite, carbon black and CNTs was found effective in reducing the cell resistance from 165 to 68, 23 and 49 Ohm respectively, and increasing the specific capacitance of the AC electrodes from 3 to 7, 17, 32 F g-1 respectively. Since the addition of CNTs can produce the highest specific capacitance, CNTs were chosen as a conductive material to produce AC composite electrodes that were added with 2.5 %, 5 % and 10 % (by weight) electro-active material namely ruthenium oxide; PVDF binder and CNTs contents were kept at 5 % by weight in each AC composite produced. The highest specific capacitance of the cells obtained in this study was 86 F g-1, i.e. for the cell with the resistance of 15 Ohm and composite electrode consists of 5 % ruthenium oxide.

  4. Impedance spectroscopic analysis of composite electrode from activated carbon/conductive materials/ruthenium oxide for supercapacitor applications

    SciTech Connect

    Taer, E.; Awitdrus,; Farma, R.; Deraman, M. Talib, I. A.; Ishak, M. M.; Omar, R.; Dolah, B. N. M.; Basri, N. H.; Othman, M. A. R.; Kanwal, S.

    2015-04-16

    Activated carbon powders (ACP) were produced from the KOH treated pre-carbonized rubber wood sawdust. Different conductive materials (graphite, carbon black and carbon nanotubes (CNTs)) were added with a binder (polivinylidene fluoride (PVDF)) into ACP to improve the supercapacitive performance of the activated carbon (AC) electrodes. Symmetric supercapacitor cells, fabricated using these AC electrodes and 1 molar H{sub 2}SO{sub 4} electrolyte, were analyzed using a standard electrochemical impedance spectroscopy technique. The addition of graphite, carbon black and CNTs was found effective in reducing the cell resistance from 165 to 68, 23 and 49 Ohm respectively, and increasing the specific capacitance of the AC electrodes from 3 to 7, 17, 32 F g{sup −1} respectively. Since the addition of CNTs can produce the highest specific capacitance, CNTs were chosen as a conductive material to produce AC composite electrodes that were added with 2.5 %, 5 % and 10 % (by weight) electro-active material namely ruthenium oxide; PVDF binder and CNTs contents were kept at 5 % by weight in each AC composite produced. The highest specific capacitance of the cells obtained in this study was 86 F g{sup −1}, i.e. for the cell with the resistance of 15 Ohm and composite electrode consists of 5 % ruthenium oxide.

  5. Two- and three-electrode impedance studies on 18650 Li-ion cells

    NASA Astrophysics Data System (ADS)

    Nagasubramanian, G.

    Two- and three-electrode impedance measurements were made on 18650 Li-ion cells at different temperatures ranging from 35°C to -40°C. The ohmic resistance of the cell is nearly constant in the temperature range studied although the total cell impedance increases by an order of magnitude in the same temperature range. In contrast to what is commonly believed, we show from our three-electrode impedance results that, the increase in cell impedance comes mostly from the cathode and not from the anode. Further, the anode and cathode contribute to both the impedance loops (in the NyQuist plot).

  6. Two and Three-Electrode Impedance Studies on 18650 Li-Ion Cells

    SciTech Connect

    Nagasubramanian, Ganesan

    1999-08-11

    Two and three electrode impedance measurements were made on 18650 Li-ion cells at different QB temperatures ranging from 35 C to {minus}40 C. The ohmic resistance of the cell is nearly constant the temperature range studied although the total cell impedance increases by an order of magnitude in the same temperature range. In contrast to what is commonly believed, we show from our three-electrode impedance results that, the increase in cell impedance comes mostly from the cathode and not from the anode. Further, the anode and cathode contribute to both the impedance loops (in the NyQuist plot).

  7. Spectroscopic study of solar twins and analogues

    NASA Astrophysics Data System (ADS)

    Datson, Juliet; Flynn, Chris; Portinari, Laura

    2015-02-01

    Context. Many large stellar surveys have been and are still being carried out, providing huge amounts of data, for which stellar physical parameters will be derived. Solar twins and analogues provide a means to test the calibration of these stellar catalogues because the Sun is the best-studied star and provides precise fundamental parameters. Solar twins should be centred on the solar values. Aims: This spectroscopic study of solar analogues selected from the Geneva-Copenhagen Survey (GCS) at a resolution of 48 000 provides effective temperatures and metallicities for these stars. We test whether our spectroscopic parameters, as well as the previous photometric calibrations, are properly centred on the Sun. In addition, we search for more solar twins in our sample. Methods: The methods used in this work are based on literature methods for solar twin searches and on methods we developed in previous work to distinguish the metallicity-temperature degeneracies in the differential comparison of spectra of solar analogues versus a reference solar reflection spectrum. Results: We derive spectroscopic parameters for 148 solar analogues (about 70 are new entries to the literature) and verify with a-posteriori differential tests that our values are well-centred on the solar values. We use our dataset to assess the two alternative calibrations of the GCS parameters; our methods favour the latest revision. We show that the choice of spectral line list or the choice of asteroid or time of observation does not affect the results. We also identify seven solar twins in our sample, three of which are published here for the first time. Conclusions: Our methods provide an independent means to differentially test the calibration of stellar catalogues around the values of a well-known benchmark star, which makes our work interesting for calibration tests of upcoming Galactic surveys. Based on observations made with ESO Telescopes at the La Silla Observatory under programme ID 077.D

  8. Predictive Mechanistic Model for the Electrical Impedance and Intensity-Modulated Photocurrent and Photovoltage Spectroscopic Responses of an Organic Bulk Heterojunction Solar Cell

    NASA Astrophysics Data System (ADS)

    Set, Ying Ting; Birgersson, Erik; Luther, Joachim

    2016-05-01

    We develop a predictive and mechanistic model for the intensity-modulated photocurrent spectroscopic (IMPS), intensity-modulated photovoltage spectroscopic (IMVS), and electrical impedance spectroscopic (EIS) responses of organic bulk heterojunction (BHJ) solar cells. Unlike the dominant analytical framework—equivalent circuit analysis—the model uses physical parameters that directly reflect the device's fundamental electronic mechanisms, eliminating the ambiguity associated with interpreting phenomenological parameters. Formulated in the frequency domain, the model is a computationally efficient tool for extracting parameters from the measured spectra. With a set of physical parameters representing a device, we predict the device's spectra (a) in techniques employing different methods of perturbing a device and (b) at different bias voltages and illumination intensities. The predicted spectra show good agreement with the measured ones. By quantifying the device's internal electric field and charge carrier concentration and relating them to the spectra, we determine that the IMPS responses at the short-circuit condition and the IMVS responses at the open-circuit condition directly reflect the charge carrier extraction and recombination, respectively. Furthermore, the EIS response indicates the device's recombination time scale at different bias voltages.

  9. Impact of hydrogen concentrations on the impedance spectroscopic behavior of Pd-sensitized ZnO nanorods

    PubMed Central

    2013-01-01

    ZnO nanorods were synthesized using a low-cost sol-gel spin coating technique. The synthesized nanorods were consisted of hexagonal phase having c-axis orientation. SEM images reflected perpendicular ZnO nanorods forming bridging network in some areas. The impact of different hydrogen concentrations on the Pd-sensitized ZnO nanorods was investigated using an impedance spectroscopy (IS). The grain boundary resistance (Rgb) significantly contributed to the sensing properties of hydrogen gas. The boundary resistance was decreased from 11.95 to 3.765 kΩ when the hydrogen concentration was increased from 40 to 360 ppm. IS gain curve showed a gain of 6.5 for 360 ppm of hydrogen at room temperature. Nyquist plot showed reduction in real part of impedance at low frequencies on exposure to different concentrations of hydrogen. Circuit equivalency was investigated by placing capacitors and resistors to identify the conduction mechanism according to complex impedance Nyquist plot. Variations in nanorod resistance and capacitance in response to the introduction of various concentrations of hydrogen gas were obtained from the alternating current impedance spectra. PMID:23399029

  10. Impact of hydrogen concentrations on the impedance spectroscopic behavior of Pd-sensitized ZnO nanorods

    NASA Astrophysics Data System (ADS)

    Kashif, Muhammad; Ali, Md Eaqub; Ali, Syed M. Usman; Hashim, Uda; Hamid, Sharifah Bee Abd

    2013-02-01

    ZnO nanorods were synthesized using a low-cost sol-gel spin coating technique. The synthesized nanorods were consisted of hexagonal phase having c-axis orientation. SEM images reflected perpendicular ZnO nanorods forming bridging network in some areas. The impact of different hydrogen concentrations on the Pd-sensitized ZnO nanorods was investigated using an impedance spectroscopy (IS). The grain boundary resistance ( R gb) significantly contributed to the sensing properties of hydrogen gas. The boundary resistance was decreased from 11.95 to 3.765 kΩ when the hydrogen concentration was increased from 40 to 360 ppm. IS gain curve showed a gain of 6.5 for 360 ppm of hydrogen at room temperature. Nyquist plot showed reduction in real part of impedance at low frequencies on exposure to different concentrations of hydrogen. Circuit equivalency was investigated by placing capacitors and resistors to identify the conduction mechanism according to complex impedance Nyquist plot. Variations in nanorod resistance and capacitance in response to the introduction of various concentrations of hydrogen gas were obtained from the alternating current impedance spectra.

  11. Measurement uncertainty in pulmonary vascular input impedance and characteristic impedance estimated from pulsed-wave Doppler ultrasound and pressure: clinical studies on 57 pediatric patients.

    PubMed

    Tian, Lian; Hunter, Kendall S; Kirby, K Scott; Ivy, D Dunbar; Shandas, Robin

    2010-06-01

    Pulmonary vascular input impedance better characterizes right ventricular (RV) afterload and disease outcomes in pulmonary hypertension compared to the standard clinical diagnostic, pulmonary vascular resistance (PVR). Early efforts to measure impedance were not routine, involving open-chest measurement. Recently, the use of pulsed-wave (PW) Doppler-measured velocity to non-invasively estimate instantaneous flow has made impedance measurement more practical. One critical concern remains with clinical use: the measurement uncertainty, especially since previous studies only incorporated random error. This study utilized data from a large pediatric patient population to comprehensively examine the systematic and random error contributions to the total impedance uncertainty and determined the least error prone methodology to compute impedance from among four different methods. We found that the systematic error contributes greatly to the total uncertainty and that one of the four methods had significantly smaller propagated uncertainty; however, even when this best method is used, the uncertainty can be large for input impedance at high harmonics and for the characteristic impedance modulus. Finally, we found that uncertainty in impedance between normotensive and hypertensive patient groups displays no significant difference. It is concluded that clinical impedance measurement would be most improved by advancements in instrumentation, and the best computation method is proposed for future clinical use of the input impedance. PMID:20410558

  12. Quadrupole resonance spectroscopic study of narcotic materials

    NASA Astrophysics Data System (ADS)

    Rayner, Timothy J.; West, Rebecca; Garroway, Allen N.; Lyndquist, R.; Yesinowski, James P.

    1997-02-01

    Bulk narcotic detection systems based upon Quadrupole Resonance Analysis (QRA) technology have a major advantage over imaging technologies, in that QRA is chemical-specific and consequently has a lower rate of false alarms. QRA is a magnetic resonance technology which occurs as a result of the inherent molecular properties of the atomic nuclei in crystalline and amorphous solids. The QRA response is characterized by 1) the precessional frequency of the nucleus, and 2) the nature of the electric field gradient experienced by the nucleus,due to its molecular environment. Another important detection parameter is linewidth, resonant quality. All of these parameters depend on sample purity and manufacturing process. Quantum Magnetics recently carried out a study on the QRA signatures of various narcotic materials with the support of the US Army, US Customs, and the Office of National Drug Control Policy. The aim of the study was to fully characterize the variation in QRA spectroscopic parameters of different samples of cocaine base and cocaine hydrochloride. The results from this study ar discussed here.

  13. Electrochemical impedance study of the hematite/water interface.

    PubMed

    Shimizu, Kenichi; Lasia, Andrzej; Boily, Jean-François

    2012-05-22

    Reactions taking place on hematite (α-Fe(2)O(3)) surfaces in contact with aqueous solutions are of paramount importance to environmental and technological processes. The electrochemical properties of the hematite/water interface are central to these processes and can be probed by open circuit potentials and cyclic voltammetric measurements of semiconducting electrodes. In this study, electrochemical impedance spectroscopy (EIS) was used to extract resistive and capacitive attributes of this interface on millimeter-sized single-body hematite electrodes. This was carried out by developing equivalent circuit models for impedance data collected on a semiconducting hematite specimen equilibrated in solutions of 0.1 M NaCl and NH(4)Cl at various pH values. These efforts produced distinct sets of capacitance values for the diffuse and compact layers of the interface. Diffuse layer capacitances shift in the pH 3-11 range from 2.32 to 2.50 μF·cm(-2) in NaCl and from 1.43 to 1.99 μF·cm(-2) in NH(4)Cl. Furthermore, these values reach a minimum capacitance at pH 9, near a probable point of zero charge for an undefined hematite surface exposing a variety of (hydr)oxo functional groups. Compact layer capacitances pertain to the transfer of ions (charge carriers) from the diffuse layer to surface hydroxyls and are independent of pH in NaCl, with values of 32.57 ± 0.49 μF·cm(-2)·s(-φ). However, they decrease with pH in NH(4)Cl from 33.77 at pH 3.5 to 21.02 μF·cm(-2)·s(-φ) at pH 10.6 because of the interactions of ammonium species with surface (hydr)oxo groups. Values of φ (0.71-0.73 in NaCl and 0.56-0.67 in NH(4)Cl) denote the nonideal behavior of this capacitor, which is treated here as a constant phase element. Because electrode-based techniques are generally not applicable to the commonly insulating metal (oxyhydr)oxides found in the environment, this study presents opportunities for exploring mineral/water interface chemistry by EIS studies of single

  14. Fundamental spectroscopic studies of carbenes and hydrocarbon radicals

    SciTech Connect

    Gottlieb, C.A.; Thaddeus, P.

    1993-12-01

    Highly reactive carbenes and carbon-chain radicals are studied at millimeter wavelengths by observing their rotational spectra. The purpose is to provide definitive spectroscopic identification, accurate spectroscopic constants in the lowest vibrational states, and reliable structures of the key intermediates in reactions leading to aromatic hydrocarbons and soot particles in combustion.

  15. An impedance study on admiralty brass dezincification originated by microbiologically influenced corrosion.

    PubMed

    Ibars, J R; Polo, J L; Moreno, D A; Ranninger, C; Bastidas, J M

    2004-09-30

    In this article we describe a field study of biofouling and microbiologically influenced corrosion (MIC) of admiralty brass heat exchanger tubes in contact with running fresh water on the river Tagus close to Almaraz nuclear power plant in Spain. Dezincification originated by biofouling and MIC was studied using impedance, polarization resistance, gravimetric, scanning electron microscopy (SEM), and X-ray diffraction (XRD) measurements. Close correlation was observed between the biofilms formed and the corrosion process (dezincification) using the different experimental techniques. Impedance data showed a capacitive behavior including two time constants. Kramers-Kronig (KK) transforms were used to validate impedance data. The admiralty tubes' impedance data satisfied the KK relations. PMID:15334412

  16. Otosclerosis in a black child: diagnostic acoustic impedance studies.

    PubMed

    Schweitzer, V G; Lilly, D J

    1984-10-01

    Otosclerosis classically describes an osteodystrophic change in the bony labyrinth and stapes footplate, of autosomal dominant inheritance, reported rare under the age of 5, extremely "rare" in the Oriental and Black race, "non-existent" in the American Indian, and with a clinical incidence of 5 per 1000 Caucasians. The differential diagnosis of a non-effusion conductive hearing loss in a child should include otosclerosis, congenital malleus or footplate fixation, tympanosclerotic fixation, congenital cholesteatoma, lysis of the incus long process, Paget's disease, osteogenesis imperfecta, and fibromuscular hyperplasia of the renal artery. Presented is a case report of a 14-year-old black male with bilateral clinical otosclerosis and a persistent stapedial artery. Preoperative multiple-frequency tympanometry and Zwislocki acoustic reactance and resistance analysis demonstrated absence of the "W" resonance pattern on high-frequency tympanometry and the classic friction and stiffness patterns of otosclerotic fixation. Repeat multiple-frequency tympanometry testing post-stapedectomy demonstrated prosthesis articulation. Prosthesis position can be monitored postoperatively by these acoustic impedance studies. PMID:6500827

  17. The fabrication of low-impedance nanoporous gold multiple-electrode arrays for neural electrophysiology studies

    PubMed Central

    Seker, Erkin; Berdichevsky, Yevgeny; Begley, Matthew R; Reed, Michael L; Staley, Kevin J; Yarmush, Martin L

    2011-01-01

    Neural electrodes are essential tools for the study of the nervous system and related diseases. Low electrode impedance is a figure of merit for sensitive detection of neural electrical activity and numerous studies have aimed to reduce impedance. Unfortunately, most of these efforts have been tethered by a combination of poor functional coating adhesion, complicated fabrication techniques, and poor fabrication repeatability. We address these issues with a facile method for reliably producing multiple-electrode arrays with low impedance by patterning highly adherent nanoporous gold films using conventional microfabrication techniques. The high surface area-to-volume ratio of self-assembled nanoporous gold results in a more than 25-fold improvement in the electrode-electrolyte impedance, where at 1 kHz, 850 kΩ impedance for conventional Au electrodes is reduced to 30 kΩ for nanoporous gold electrodes. Low impedance provides a superior signal-to-noise ratio for detection of neural activity in noisy environments. We systematically studied the effect of film morphology on electrode impedance and successfully recorded field potentials from rat hippocampal slices. Here, we present our fabrication approach, the relationship between film morphology and impedance, and field potential recordings. PMID:20203356

  18. Synthesis and Characterization of Ba(Zr{sub x}Ti{sub 1-x})O{sub 3} Solid Solutions Using Impedance Spectroscopic Techniques

    SciTech Connect

    Bajpai, P. K.; Mohan, C. R. K.

    2011-11-22

    Technologically important solid solutions of Ba(Zr{sub x}Ti{sub 1-x})O{sub 3} are synthesized using conventional solid state route. Relatively dense and single phase ceramics are confirmed using X-ray diffraction. Homogeneous and micron size grain growth is characterized using SEM. Impedance spectroscopy is used to study the electrical properties of ceramics. Broad and diffuse impedance loss peak is observed above 250 deg. C, which shifts towards higher frequency with increase in temperature. The distribution of relaxation frequency may be associated with the B-site cationic disorder due to the random distribution of (Zr{sup 4+}/Ti{sup +4}) having different ionic radii. Impedance relaxation obeys the Arrhenius relation with activation energy, E{tau} is 0.31 eV and 0.48 eV for BZT compositions with x = 0.10 and 0.15 respectively. Equivalent circuit representation using two RC element coupled in parallel is used to analyse the impedance response.

  19. Studies of deionization and impedance spectroscopy for blood analyzer

    NASA Astrophysics Data System (ADS)

    Kwong, Charlotte C.; Li, Nan; Ho, Chih-Ming

    2005-11-01

    Blood analysis provides vital information for health conditions. For instance, typical infection response is correlated to an elevated White Blood Cell (WBC) count, while low Red Blood Cell (RBC) count, hemoglobin and hematocrit are caused by anemia or internal bleeding. We are developing two essential modules, deionization (DI) chip and microfluidic cytometer with impedance spectroscopy flow, for enabling the realization of a single platform miniaturized blood analyzer. In the proposed analyzer, blood cells are preliminarily sorted by Dielectrophoretic (DEP) means into sub-groups, differentiated and counted by impedance spectroscopy in a flow cytometer. DEP techniques have been demonstrated to stretch DNA, align Carbon Nanotubes (CNT) and trap cells successfully. However, DEP manipulation does not function in biological media with high conductivity. The DI module is designed to account for this challenge. H Filter will serve as an ion extraction platform in a microchamber. Sample and buffer do not mix well in micro scale allowing the ions being extracted by diffusion without increasing the volume. This can keep the downstream processing time short. Micro scale hydrodynamic focusing is employed to place single cell passing along the central plane of the flow cytometer module. By applying an AC electrical field, suspended cells are polarized, membrane capacitance C m, cytoplasm conductivity σ c, and cytoplasm permittivity ɛ c will vary as functions of frequency. Tracing back the monitored current, the numbers of individual cell species can be evaluated.

  20. A Comparative Study of Four Impedance Eduction Methodologies Using Several Test Liners

    NASA Technical Reports Server (NTRS)

    Watson, Willie R.; Jones, Michael G.

    2013-01-01

    A comparative study of four commonly used impedance eduction methods is presented for a range of liner structures and test conditions. Two of the methods are restricted to uniform flow while the other two accommodate both uniform and boundary layer flows. Measurements on five liner structures (a rigid-wall insert, a ceramic tubular liner, a wire mesh liner, a low porosity conventional liner, and a high porosity conventional liner) are obtained using the NASA Langley Grazing Flow Impedance Tube. The educed impedance of each liner is presented for forty-two test conditions (three Mach numbers and fourteen frequencies). In addition, the effects of moving the acoustic source from upstream to downstream and the refractive effects of the mean boundary layer on the wire mesh liner are investigated. The primary conclusions of the study are that: (1) more accurate results are obtained for the upstream source, (2) the uniform flow methods produce nearly identical impedance spectra at and below Mach 0.3 but significant scatter in the educed impedance occurs at the higher Mach number, (3) there is better agreement in educed impedance among the methods for the conventional liners than for the rigid-wall insert, ceramic, or wire mesh liner, and (4) the refractive effects of the mean boundary layer on the educed impedance of the wire mesh liner are generally small except at Mach 0.5.

  1. Fourier transform infrared spectroscopic study of truffles

    NASA Astrophysics Data System (ADS)

    Zhao, Dezhang; Liu, Gang; Song, Dingshan; Liu, Jian-hong; Zhou, Yilan; Ou, Jiaming; Sun, Shizhong

    2006-01-01

    Truffles are rare wild growing edible mushrooms belonging to Ascomycetes. In this paper, Fourier transform infrared (FTIR) spectroscopy was used to obtain vibrational spectra of truffles. The results show that the mushrooms exhibit characteristic spectra. The two strongest absorption bands appear at about 1077cm -1 and 1040 cm -1, which were described as C-O stretching in carbohydrate. The vibrational spectra indicate that the main compositions of the truffles are polysaccharide and protein. According to the characteristics bands and absorption ratios of spectra, different species of truffles can be discriminated. It is also found the great changes between moldy and healthy truffles, which the major differences are observed in the bands of protein. In addition, FTIR spectral differences are observed between the same species of truffles from different producing areas. It is showed that the FTIR spectroscopic method is valuable tool for rapid and nondestructive analysis of truffles prior to any extraction method used.

  2. Comparative Study of Impedance Eduction Methods, Part 2: NASA Tests and Methodology

    NASA Technical Reports Server (NTRS)

    Jones, Michael G.; Watson, Willie R.; Howerton, Brian M.; Busse-Gerstengarbe, Stefan

    2013-01-01

    A number of methods have been developed at NASA Langley Research Center for eduction of the acoustic impedance of sound-absorbing liners mounted in the wall of a flow duct. This investigation uses methods based on the Pridmore-Brown and convected Helmholtz equations to study the acoustic behavior of a single-layer, conventional liner fabricated by the German Aerospace Center and tested in the NASA Langley Grazing Flow Impedance Tube. Two key assumptions are explored in this portion of the investigation. First, a comparison of results achieved with uniform-flow and shear-flow impedance eduction methods is considered. Also, an approach based on the Prony method is used to extend these methods from single-mode to multi-mode implementations. Finally, a detailed investigation into the effects of harmonic distortion on the educed impedance is performed, and the results are used to develop guidelines regarding acceptable levels of harmonic distortion

  3. Study of dielectric and impedance properties of Mn ferrites

    NASA Astrophysics Data System (ADS)

    Mujasam Batoo, Khalid

    2011-02-01

    The paper reports on the effect of Al substitution on the structural and electrical properties of bulk ferrite series of basic composition MnFe 2-2 xAl 2 xO 4 (0.0≤ x≤0.5) synthesized using solid state reaction method. XRD analysis confirms that all the samples exhibit single phase cubic spinel structure excluding presence of any secondary phase. The dielectric constant shows a normal behaviour with frequency, whereas the loss tangent exhibits an anomalous behaviour with frequency for all compositions. Variation of dielectric properties and ac conductivity with frequency reveals that the dispersion is due to Maxwell-Wagner type of interfacial polarization in general and hopping of charge between Fe +2 and Fe +3 as well as between Mn +2 and Mn +3 ions at octahedral sites. The complex impedance plane spectra shows the presence of two semicircles up to x=0.2, and only one semicircle for the higher values of x. The analysis of the data shows that the resistive and capacitive properties of the Mn ferrite are mainly due to processes associated with grain and grain boundaries.

  4. Spectroscopic study of low-lying {sup 16}N levels

    SciTech Connect

    Bardayan, D. W.; Nesaraja, C. D.; Pain, S. D.; Smith, M. S.; O'Malley, P. D.; Cizewski, J. A.; Hatarik, R.; Peters, W. A.; Blackmon, J. C.; Chae, K. Y.; Jones, K. L.; Moazen, B. H.; Paulauskas, S.; Pittman, S. T.; Schmitt, K. T.; Chipps, K. A.; Kozub, R. L.; Shriner, J. F. Jr.; Matei, C.

    2008-11-15

    The magnitude of the {sup 15}N(n,{gamma}){sup 16}N reaction rate in asymptotic giant branch stars depends directly on the neutron spectroscopic factors of low-lying {sup 16}N levels. A new study of the {sup 15}N(d,p){sup 16}N reaction is reported populating the ground and first three excited states in {sup 16}N. The measured spectroscopic factors are near unity as expected from shell model calculations, resolving a long-standing discrepancy with earlier measurements that had never been confirmed or understood. Updated {sup 15}N(n,{gamma}){sup 16}N reaction rates are presented.

  5. Transport and spectroscopic studies of liquid and polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Bopege, Dharshani Nimali

    Liquid and polymer electrolytes are interesting and important materials to study as they are used in Li rechargeable batteries and other electrochemical devices. It is essential to investigate the fundamental properties of electrolytes such as ionic conductivity, diffusion, and ionic association to enhance battery performance in different battery markets. This dissertation mainly focuses on the temperature-dependent charge and mass transport processes and ionic association of different electrolyte systems. Impedance spectroscopy and pulsed field gradient nuclear magnetic resonance spectroscopy were used to measure the ionic conductivity and diffusion coefficients of ketone and acetate based liquid electrolytes. In this study, charge and mass transport in non-aqueous liquid electrolytes have been viewed from an entirely different perspective by introducing the compensated Arrhenius formalism. Here, the conductivity and diffusion coefficient are written as an Arrhenius-like expression with a temperature-dependent static dielectric constant dependence in the exponential prefactor. The compensated Arrhenius formalism reported in this dissertation very accurately describes temperature-dependent conductivity data for acetate and ketone-based electrolytes as well as temperature-dependent diffusion data of pure solvents. We found that calculated average activation energies of ketone-based electrolytes are close to each other for both conductivity and diffusion data (in the range 24-26 kJ/mol). Also, this study shows that average activation energies of acetate-based electrolytes are higher than those for the ketone systems (in the range 33-37 kJ/mol). Further, we observed higher dielectric constants and ionic conductivities for both dilute and concentrated ketone solutions with temperature. Vibrational spectroscopy (Infrared and Raman) was used to probe intermolecular interactions in both polymer and liquid electrolytes, particularly those which contain lithium

  6. Halo Nucleus Be11: A Spectroscopic Study via Neutron Transfer

    NASA Astrophysics Data System (ADS)

    Schmitt, K. T.; Jones, K. L.; Bey, A.; Ahn, S. H.; Bardayan, D. W.; Blackmon, J. C.; Brown, S. M.; Chae, K. Y.; Chipps, K. A.; Cizewski, J. A.; Hahn, K. I.; Kolata, J. J.; Kozub, R. L.; Liang, J. F.; Matei, C.; Matoš, M.; Matyas, D.; Moazen, B.; Nesaraja, C.; Nunes, F. M.; O'Malley, P. D.; Pain, S. D.; Peters, W. A.; Pittman, S. T.; Roberts, A.; Shapira, D.; Shriner, J. F., Jr.; Smith, M. S.; Spassova, I.; Stracener, D. W.; Villano, A. N.; Wilson, G. L.

    2012-05-01

    The best examples of halo nuclei, exotic systems with a diffuse nuclear cloud surrounding a tightly bound core, are found in the light, neutron-rich region, where the halo neutrons experience only weak binding and a weak, or no, potential barrier. Modern direct-reaction measurement techniques provide powerful probes of the structure of exotic nuclei. Despite more than four decades of these studies on the benchmark one-neutron halo nucleus Be11, the spectroscopic factors for the two bound states remain poorly constrained. In the present work, the Be10(d,​p) reaction has been used in inverse kinematics at four beam energies to study the structure of Be11. The spectroscopic factors extracted using the adiabatic model were found to be consistent across the four measurements and were largely insensitive to the optical potential used. The extracted spectroscopic factor for a neutron in an nℓj=2s1/2 state coupled to the ground state of Be10 is 0.71(5). For the first excited state at 0.32 MeV, a spectroscopic factor of 0.62(4) is found for the halo neutron in a 1p1/2 state.

  7. Studies of longitudinal profile of electron bunches and impedance measurements at Indus-2 synchrotron radiation source

    NASA Astrophysics Data System (ADS)

    Garg, Akash Deep; Yadav, S.; Kumar, Mukesh; Shrivastava, B. B.; Karnewar, A. K.; Ojha, A.; Puntambekar, T. A.

    2016-04-01

    Indus-2 is a 3rd generation synchrotron radiation source at the Raja Ramanna Centre for Advanced Technology (RRCAT) in India. We study the longitudinal profile of electrons in Indus-2 by using dual sweep synchroscan streak camera at visible diagnostic beamline. In this paper, the longitudinal profiles of electron bunch are analyzed by filling beam current in a single bunch mode. These studies are carried at injection energy (550 MeV) and at ramped beam energy (2.5 GeV). The effects of the wakefield generated interactions between the circulating electrons and the surrounding vacuum chamber are analyzed in terms of measured effects on longitudinal beam distribution. The impedance of the storage ring is obtained by fitting the solutions of Haissinski equation to the measured bunch lengthening with different impedance models. The impedance of storage ring obtained by a series R+L impedance model indicates a resistance (R) of 1350±125 Ω, an inductance (L) of 180±25 nH and broadband impedance of 2.69 Ω. These results are also compared with the values obtained from measured synchronous phase advancing and scaling laws. These studies are very useful in better understanding and control of the electromagnetic interactions.

  8. Single cells and intracellular processes studied by a plasmonic-based electrochemical impedance microscopy

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Foley, Kyle; Shan, Xiaonan; Wang, Shaopeng; Eaton, Seron; Nagaraj, Vinay J.; Wiktor, Peter; Patel, Urmez; Tao, Nongjian

    2011-03-01

    Electrochemical impedance spectroscopy is a crucial tool for the detection and study of various biological substances, from DNA and proteins to viruses and bacteria. It does not require any labelling species, and methods based on it have been developed to study cellular processes (such as cell spreading, adhesion, invasion, toxicology and mobility). However, data have so far lacked spatial information, which is essential for investigating heterogeneous processes and imaging high-throughput microarrays. Here, we report an electrochemical impedance microscope based on surface plasmon resonance that resolves local impedance with submicrometre spatial resolution. We have used an electrochemical impedance microscope to monitor the dynamics of cellular processes (apoptosis and electroporation of individual cells) with millisecond time resolution. The high spatial and temporal resolution makes it possible to study individual cells, but also resolve subcellular structures and processes without labels, and with excellent detection sensitivity (~2 pS). We also describe a model that simulates cellular and electrochemical impedance microscope images based on local dielectric constant and conductivity.

  9. Monitoring of CRT by means of impedance multiple measurements - simulation studies

    NASA Astrophysics Data System (ADS)

    Lewandowska, M.; Wtorek, J.; Bujnowski, A.; Mierzejewski, L.

    2010-04-01

    Cardiac resynchronization therapy (CRT) is a very promising treatment for patients with congestive heart failure. An Impedance Cardiography (ICG) is used for evaluation of heart mechanical activity. A simulation study with the use of a FEM model was performed. The developed realistic model of the thorax, based on CT data obtained from examination of a 68-year-old man, consisted of 212 000 tetrahedral elements. Different configurations of electrodes allowing extraction of ventricular components from impedance signal were examined. The associated sensitivity distributions were calculated for different phases of heart contraction and blood distribution inside the thorax. These sensitivity distributions were compared to that obtained for a uniform model of the thorax described by average conductivity. The performed simulation studies proved that it is possible to extract ventricular components of impedance signal with a reasonable accuracy.

  10. Development of a new rapid measurement technique for fish embryo membrane permeability studies using impedance spectroscopy

    PubMed Central

    Zhang, T.; Wang, R.Y.; Bao, Q-Y.; Rawson, D.M.

    2006-01-01

    Information on fish embryo membrane permeability is vital in their cryopreservation. Whilst conventional volumetric measurement based assessment methods have been widely used in fish embryo membrane permeability studies, they are lengthy and reduce the capacity for multi-embryo measurement during an experimental run. A new rapid ‘real-time’ measurement technique is required to determine membrane permeability during cryoprotectant treatment. In this study, zebrafish (Danio rerio) embryo membrane permeability to cryoprotectants was investigated using impedance spectroscopy. An embryo holding cell, capable of holding up to 10 zebrafish embryos was built incorporating the original system electrods for measuring the impedance spectra. The holding cell was tested with deionised water and a series of KCl solutions with known conductance values to confirm the performance of the modified system. Untreated intact embryos were then tested to optimise the loading capacity and sensitivity of the system. To study the impedance changes of zebrafish embryos during cryoprotectant exposure, three, six or nine embryos at 50% epiboly stage were loaded into the holding cell in egg water, which was then removed and replaced by 0.5, 1.0, 2.0 or 3 M methanol or dimethyl sulfoxide (DMSO). The impedance changes of the loaded embryos in different cryoprotectant solutions were monitored over 30 min at 22 °C, immediately following embryo exposure to cryoprotectants, at the frequency range of 10–106 Hz. The impedance changes of the embryos in egg water were used as controls. Results from this study showed that the optimum embryo loading level was six embryos per cell for each experimental run. The optimum frequency was identified at 103.14 or 1380 Hz which provided good sensitivity and reproducibility. Significant impedance changes were detected after embryos were exposed to different concentrations of cryoprotectants. The results agreed well with those obtained from conventional

  11. Inhibition of urinary calculi -- a spectroscopic study

    NASA Astrophysics Data System (ADS)

    Manciu, Felicia; Govani, Jayesh; Durrer, William; Reza, Layra; Pinales, Luis

    2008-10-01

    Although a considerable number of investigations have already been undertaken and many causes such as life habits, metabolic disorders, and genetic factors have been noted as sources that accelerate calculi depositions and aggregations, there are still plenty of unanswered questions regarding efficient inhibition and treatment mechanisms. Thus, in an attempt to acquire more insights, we propose here a detailed scientific study of kidney stone formation and growth inhibition based on a traditional medicine approach with Rotula Aquatica Lour (RAL) herbal extracts. A simplified single diffusion gel growth technique was used for synthesizing the samples for the present study. The unexpected Zn presence in the sample with RAL inhibitor, as revealed by XPS measurements, explains the inhibition process and the dramatic reflectance of the incident light observed in the infrared transmission studies. Raman data demonstrate potential binding of the inhibitor with the oxygen of the kidney stone. Photoluminescence results corroborate to provide additional evidence of Zn-related inhibition.

  12. Spectroscopic study of bituminous oxidative stress.

    PubMed

    Masmoudi, H; Rebufa, C; Raffi, J; Permanyer, A; Kister, J

    2004-05-01

    Bitumen, as each organic substance, is a product which alters over time. Indeed, roads deteriorate under the effect of several phenomena. A number of studies have been undertaken to increase the quality of road's coating, mostly by adding polymer to bitumen. This work was based on the study, by electron paramagnetic resonance (EPR), FTIR and Synchronous UV fluorescence, of different base and modified bitumens after different treatments used to simulate the ageing (gamma irradiation, thermal treatment). Our purpose was to compare and correlate the results obtained by different techniques to improve the knowledge of bitumen's reactivity and evolution submitted to ageing phenomena. PMID:15134733

  13. A new approach to the study of impedance characteristics of tympanic membrane.

    PubMed

    Bogomolov, A V; Dragan, S P

    2015-01-01

    A new approach to studying the tympanic membrane impedance characteristics, based on the analysis of polyharmonic acoustic signals reflected by the tympanic membrane, is described. For this purpose, the acoustic pressure and the phase difference between the acoustic vibrations in two sections of a waveguide sealingly connecting the external auditory meatus and a generator of polyharmonic audio signals is measured. By processing the results of measurements, the estimates of the frequency-dependent reflection coefficients, absorption coefficients, and components of the acoustic impedance of the tympanic membrane are calculated. The features that principally distinguish the developed approach from other approaches are the absence of the necessity to create a positive pressure in the external auditory meatus, the absence of ultrasonic radiation into the external auditory meatus and a high-intensity sound, and the possibility of direct measurement of the tympanic membrane impedance in the audio frequency range with any step. PMID:26518544

  14. The influence of nanopore dimensions on the electrochemical properties of nanopore arrays studied by impedance spectroscopy.

    PubMed

    Kant, Krishna; Priest, Craig; Shapter, Joe G; Losic, Dusan

    2014-01-01

    The understanding of the electrochemical properties of nanopores is the key factor for better understanding their performance and applications for nanopore-based sensing devices. In this study, the influence of pore dimensions of nanoporous alumina (NPA) membranes prepared by an anodization process and their electrochemical properties as a sensing platform using impedance spectroscopy was explored. NPA with four different pore diameters (25 nm, 45 nm and 65 nm) and lengths (5 μm to 20 μm) was used and their electrochemical properties were explored using different concentration of electrolyte solution (NaCl) ranging from 1 to 100 μM. Our results show that the impedance and resistance of nanopores are influenced by the concentration and ion species of electrolytes, while the capacitance is independent of them. It was found that nanopore diameters also have a significant influence on impedance due to changes in the thickness of the double layer inside the pores. PMID:25393785

  15. Spectroscopic analysis of bones for forensic studies

    NASA Astrophysics Data System (ADS)

    Tofanelli, Mirko; Pardini, Lorenzo; Borrini, Matteo; Bartoli, Fulvio; Bacci, Alessandra; D'Ulivo, Alessandro; Pitzalis, Emanuela; Mascherpa, Marco Carlo; Legnaioli, Stefano; Lorenzetti, Giulia; Pagnotta, Stefano; de Holanda Cavalcanti, Gildo; Lezzerini, Marco; Palleschi, Vincenzo

    2014-09-01

    The elemental analysis of human bones can give information about the dietary habits of the deceased, especially in the last years of their lives, which can be useful for forensic studies. The most important requirement that must be satisfied for this kind of analysis is that the concentrations of analyzed elements are the same as ante mortem. In this work, a set of bones was analyzed using Laser-Induced Breakdown Spectroscopy (LIBS) and validated using Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), in order to compare those two techniques and to investigate the effect of possible alterations in the elemental concentrations' proportion resulting from the treatment usually applied for preparing the bones for traditional forensic analysis. The possibility that elemental concentrations' changes would occur after accidental or intentional burning of the bones was also studied.

  16. Spectroscopic studies of lead halo borate glasses

    NASA Astrophysics Data System (ADS)

    Sekhar, K. Chandra; Hameed, Abdul; Chary, M. Narasimha; Shareefuddin, Md.

    2015-06-01

    Glasses in the system xPbF2-(30-x) PbO-69B2O3-1CuO (x=5, 10, 15, 20, & 25 mole %) were prepared by melt quenching method and they are characterized by XRD to confirm the glassy nature. Electron Paramagnetic Resonance (EPR) studies at room temperature in the X-band frequencies and FTIR studies on prepared glass systems were reported. The non-linear variation of spin-Hamiltonian parameters with PbF2 content indicated the change in the ligand field strength around Cu2+ ions in the host glass. The ground state of Cu2+ ions in the glass is designated as dx2-y2 orbital (2B1g) while the observed symmetry around it is tetragonally distorted octahedral. The molecular orbital coefficients α2, β2 and β12 are evaluated for Cu2+ doped samples. From the FTIR studies it was observed that the glass made up of BO3 and BO4 units.

  17. Progress report on nuclear spectroscopic studies

    SciTech Connect

    Bingham, C.R.; Guidry, M.W.; Riedinger, L.L.; Sorensen, S.P.

    1994-02-18

    The Nuclear Physics group at the University of Tennessee, Knoxville (UTK) is involved in several aspects of heavy-ion physics including both nuclear structure and reaction mechanisms. While the main emphasis is on experimental problems, the authors have maintained a strong collaboration with several theorists in order to best pursue the physics of their measurements. During the last year they have had several experiments at the ATLAS at Argonne National Laboratory, the GAMMASPHERE at the LBL 88 Cyclotron, and with the NORDBALL at the Niels Bohr Institute Tandem. Also, they continue to be very active in the WA93/98 collaboration studying ultra-relativistic heavy ion physics utilizing the SPS accelerator at CERN in Geneva, Switzerland and in the PHENIX Collaboration at the RHIC accelerator under construction at Brookhaven National Laboratory. During the last year their experimental work has been in three broad areas: (1) the structure of nuclei at high angular momentum, (2) the structure of nuclei far from stability, and (3) ultra-relativistic heavy-ion physics. The results of studies in these particular areas are described in this document. These studies concentrate on the structure of nuclear matter in extreme conditions of rotational motion, imbalance of neutrons and protons, or very high temperature and density. Another area of research is heavy-ion-induced transfer reactions, which utilize the transfer of nucleons to states with high angular momentum to learn about their structure and to understand the transfer of particles, energy, and angular momentum in collisions between heavy ions.

  18. In situ anodization of aluminum surfaces studied by x-ray reflectivity and electrochemical impedance spectroscopy

    SciTech Connect

    Bertram, F. Evertsson, J.; Messing, M. E.; Mikkelsen, A.; Lundgren, E.; Zhang, F.; Pan, J.; Carlà, F.; Nilsson, J.-O.

    2014-07-21

    We present results from the anodization of an aluminum single crystal [Al(111)] and an aluminum alloy [Al 6060] studied by in situ x-ray reflectivity, in situ electrochemical impedance spectroscopy and ex situ scanning electron microscopy. For both samples, a linear increase of oxide film thickness with increasing anodization voltage was found. However, the slope is much higher in the single crystal case, and the break-up of the oxide film grown on the alloy occurs at a lower anodization potential than on the single crystal. The reasons for these observations are discussed as are the measured differences observed for x-ray reflectivity and electrochemical impedance spectroscopy.

  19. In situ anodization of aluminum surfaces studied by x-ray reflectivity and electrochemical impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Bertram, F.; Zhang, F.; Evertsson, J.; Carlà, F.; Pan, J.; Messing, M. E.; Mikkelsen, A.; Nilsson, J.-O.; Lundgren, E.

    2014-07-01

    We present results from the anodization of an aluminum single crystal [Al(111)] and an aluminum alloy [Al 6060] studied by in situ x-ray reflectivity, in situ electrochemical impedance spectroscopy and ex situ scanning electron microscopy. For both samples, a linear increase of oxide film thickness with increasing anodization voltage was found. However, the slope is much higher in the single crystal case, and the break-up of the oxide film grown on the alloy occurs at a lower anodization potential than on the single crystal. The reasons for these observations are discussed as are the measured differences observed for x-ray reflectivity and electrochemical impedance spectroscopy.

  20. Spectroscopic and quantum chemical studies of isocytosine

    SciTech Connect

    Tulub, A.A.; Semenov, S.G.; Stetsenko, A.I.; Yudovich, E.E.

    1988-07-01

    The methods of electronic and vibrational (IR) spectroscopy were used to study the spectral properties of isocytosine in H/sub 2/O, D/sub 2/O, chloroform, and hexane in a wide concentration interval. Quantum chemical calculations of tautomeric forms and dimers of isocytosine were carried out. The bands of the calculated and experimental spectra were assigned. The results of the quantum calculations were compared with the experimental data. The spectral bands were classified according to the type of tautomer or dimer to which they belong.

  1. Spectroscopic studies of solutes in aqueous solution.

    PubMed

    Chai, Bing-hua; Zheng, Jian-ming; Zhao, Qing; Pollack, Gerald H

    2008-03-20

    Absorption and fluorescence characteristics of aqueous solutions of salts, sugars, and amino acids were studied using UV-vis spectroscopy and spectrofluorometry. Motivation stemmed from unanticipated absorption spectral and fluorescence features of the "exclusion zone" seen adjacent to various hydrophilic surfaces. Those features implied a structure distinct from that of bulk water (Adv. Colloid Interface Sci. 2006, 127, 19). Absorption peaks at approximately 270 nm similar to those observed in the exclusion zone were seen in solutions of the following substances: salts, Nafion 117 solution/film, l-lysine, d-alanine, d-glucose and sucrose. To determine the fate of the absorbed energy, we studied the fluorescence properties of these solutions. The salts showed fluorescence emission around 480-490 nm under different excitation wavelengths. The fluorescence intensity of LiCl was higher than NaCl, which was in turn higher than KCl-the same ordering as the absorption intensities. Fluorescence of Nafion 117 solution/film, l-lysine, d-alanine, d-glucose and sucrose were observed as well, with multiple excitation wavelengths. Hence, at least some of the absorbed energy is released as fluorescence. The results show features closely similar to those observed in the exclusion zone, implying that the aqueous region around the solutes resembles the aqueous zone adjacent to hydrophilic surfaces. Both may be more extensively ordered than previously thought. PMID:18298105

  2. Nonlinear spectroscopic studies of interfacial molecular ordering

    SciTech Connect

    Superfine, R.

    1991-07-01

    The second order nonlinear optical processes of second harmonic generation and sum frequency generation are powerful new probes of surfaces. They possess unusual surface sensitivity due to the symmetry properties of the nonlinear susceptibility. In particular, infrared-visible sum frequency generation (SFG) can obtain the vibrational spectrum of sub-monolayer coverages of molecules. In this thesis, we explore the unique information that can be obtained from SFG. We take advantage of the sensitivity of SFG to the conformation of alkane chains to study the interaction between adsorbed liquid crystal molecules and surfactant treated surfaces. The sign of the SFG susceptibility depends on the sign of the molecular polarizability and the orientation, up or down, of the molecule. We experimentally determine the sign of the susceptibility and use it to determine the absolute orientation to obtain the sign of the molecular polarizability and show that this quantity contains important information about the dynamics of molecular charge distributions. Finally, we study the vibrational spectra and the molecular orientation at the pure liquid/vapor interface of methanol and water and present the most detailed evidence yet obtained for the structure of the pure water surface. 32 refs., 4 figs., 2 tabs.

  3. Progress report on nuclear spectroscopic studies

    SciTech Connect

    Bingham, C.R.; Riedinger, L.L.; Sorensen, S.P.

    1996-01-16

    The experimental program in nuclear physics at the University of Tennessee, Knoxville, is led by Professors Carrol Bingham, Lee Riedinger, and Soren Sorenseni who respectively lead the studies of the exotic decay modes of nuclei far from stability, the program of high-spin research, and our effort in relativistic heavy-ion physics. Over the years, this broad program of research has been successful partially because of the shared University resources applied to this group effort. The proximity of the Oak Ridge National Laboratory has allowed us to build extremely strong programs of joint research, and in addition to play an important leadership role in the Joint Institute for Heavy Ion Research (JIHIR). Our experimental program is also very closely linked with those at other national laboratories: Argonne (collaborations involving the Fragment Mass Analyzer (FMA) and {gamma}-ray arrays), Brookhaven (the RHIC and Phenix projects), and Berkeley (GAMMASPHERE). We have worked closely with a variety of university groups in the last three years, especially those in the UNISOR and now UNIRIB collaborations. And, in all aspects of our program, we have maintained close collaborations with theorists, both to inspire the most exciting experiments to perform and to extract the pertinent physics from the results. The specific areas discussed in this report are: properties of high-spin states; study of low-energy levels of nuclei far from stability; and high energy heavy-ion physics.

  4. Spectroscopic studies of silver boro tellurite glasses

    SciTech Connect

    Kumar, E. Ramesh Kumari, K. Rajani Rao, B. Appa Bhikshamaiah, G.

    2014-04-24

    The FTIR absorption and Raman scattering studies were used to obtain the structural information of AgI−Ag{sub 2}O−[(1−x)B{sub 2}O{sub 3}−xTeO{sub 2}] (x=0 to 1 mol% in steps of 0.2) glasses. The glassy nature of the compounds has been confirmed by X-ray diffraction. FTIR and Raman spectra were recorded for all samples at room temperature. FTIR spectra which provides the information about the change in bond structure of the glasses. Raman spectra provide the effect of TeO{sub 2} on SBT glass system is that as increasing the concentration of TeO{sub 2} the band intensity at 707 cm{sup −1} increase.

  5. Terahertz spectroscopic study of benzodiazepine sedative hypnotics

    NASA Astrophysics Data System (ADS)

    Deng, Fusheng; Shen, Jingling; Wang, Xianfeng

    2011-08-01

    Terahertz time domain spectroscopy (THz-TDS) is used to the pure active ingredient of three benzodiazepine sedative hypnotics with similar molecular structure. The absorption spectra of them are studied in the range of 0.2~2.6THz. Based on the experiment, the theoretical simulation results of diazepam, nitrazepam and clonazepam are got by the Gaussian03 package of DFT/B3LYP/6-31G* method in single-molecule models. The experimental results show that even if the molecular structure and medicine property of them are similar, the accurate identification of them can still be done with their characteristic absorption spectra. Theoretical simulation results are well consistent with the experimental results. It demonstrates that absorption peaks of them in THz range mainly come from intra-molecular forces and are less affected by the intermolecular interaction and crystal effects.ô

  6. Spectroscopic and quantum chemical studies on bromopyrazone

    NASA Astrophysics Data System (ADS)

    Gökce, Halil; Bahçeli, Semiha

    2014-12-01

    In this study, the FT-IR, micro-Raman and UV-vis. spectra of bromopyrazone molecule, C10H8BrN3O, (with synonym,1-phenyl-4-amino-5-bromopyridazon-(6) or 5-amino-4-bromo-2-phenyl-3(2H)-pyridazinone) were recorded experimentally. The molecular structure, vibrational wavenumbers, electronic transition absorption wavelengths in ethanol solvent, HOMOs and LUMOs analyses, molecular electrostatic potential (MEP), natural bond orbitals (NBO), nonlinear optical (NLO) properties and atomic charges of bromopyrazone molecule have been calculated by using DFT/B3LYP method with 6-311++G(d,p) basis set in ground state. The obtained results show that the calculated vibrational frequencies and UV-vis. values are in a good agreement with experimental data.

  7. Spectroscopic study of acetylene and hydrogen cyanide

    NASA Astrophysics Data System (ADS)

    Rozario, Hoimonti Immaculata

    High-resolution molecular spectroscopy has been used to study acetylene line parameters and emission spectra of hydrogen cyanide. All acetylene spectra were recorded in our laboratory at the University of Lethbridge using a 3-channel tuneable diode laser spectrometer. N2-broadened line widths and N2-pressure induced line shifts have been measured for transitions in the v1+v3 band of acetylene at seven temperatures in the range 213-333K to obtain the temperature dependences of broadening and shift coefficients. The Voigt and hard-collision line profile models were used to retrieve the line parameters. The line-broadening and line-shift coefficients as well as their temperature-dependent parameters have been also evaluated theoretically, in the frame work of a semi-classical approach based on an exponential representation of the scattering operator, an intermolecular potential composed of electrostatic quadrupole--quadrupole and pairwise atom--atom interactions as well as on exact trajectories driven by an effective isotropic potential. The experimental results for both N2-broadening and shifting show good agreement with the theoretical results. We have studied the line intensities of the 1vl 20←0v120 band system from the HCN emission spectrum. The infrared emission spectrum of H12C 14N was measured at the Justus-Liebig University, Giessen, Germany. The emission spectrum was analyzed with the spectrum analysis software Symath running using Mathematica as a platform. This approach allowed us to retrieve information on band intensity parameters.

  8. Ultrafast spectroscopic studies of metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Hu, Min

    An important aim of nanoparticle research is to understand how the properties of materials depend on their size and shape. In this thesis, time-resolved spectroscopy has been used to measure the physical properties of nanometer sized objects, such as the characteristic time scale for heat dissipation and their elastic moduli. In our experiments, metal nanoparticles are excited with a sub-picosecond laser pulse, which causes a rapid increase in the lattice temperature. In the first project, the rate of heat dissipation from Au nanoparticles to their surroundings was examined for different size gold nanospheres in aqueous solution. Laser induced lattice heating can also impulsively excite the phonon modes of the particle that correlate with the expansion co-ordinates. For spherical Au particles the symmetric breathing mode is excited. Experimental results for ˜50 nm diameter Au particles were compared to a model calculation where the expansion coordinate is treated as a damped harmonic oscillator. This gives information about the excitation mechanism. In the second project, the extensional and breathing modes of cylindrical gold nanorods were studied by time-resolved spectroscopy. These experiments yield values for the elastic constants for the rods. Both the extensional mode and the breathing mode results show that gold nanorods produced by wet chemical techniques have a smaller elastic moduli than bulk gold. HR-TEM and SAED studies show that the rods have a 5-fold twinned structure with growth along the [110] crystal direction. However, neither the growth direction nor the twinning provide a simple explanation for the reduced elastic moduli measured in the experiments. In a final project, polydisperse silver nanoparticle samples were investigated. A signal due to coherently excited vibrational motion was observed. The analysis shows that the observed signal arises from the triangular-shaped particles, rather than the rods or spheres that are present in the sample

  9. Raman spectroscopic studies of disordered ferroelectric oxides

    NASA Astrophysics Data System (ADS)

    Savvinov, Alexey A.

    Relaxational properties of compositionally disordered AB03 perovskite oxides were studied. These oxides are the prototypical soft ferroelectric (FE) mode systems, and their interesting dipolar relaxational properties are determined by their long, strongly temperature-dependent correlation lengths for the dipolar interactions. The simple cases involve dilute chemical substitutions in the incipient ferroelectrics KTaO3 and SrTiO3, which exhibit relatively weak, low-temperature Debye-type relaxations. More complicated dipolar interactions are seen in B-site disordered Nb-doped KTaO3, which exhibits glass-like relaxor and relaxor-to-ferroelectric crossover behaviors at low temperatures. Finally, there is a class of more complex perovskites represented by PMN, PZN-PT and the PLT that exhibit strong, high-temperature relaxor and/or ferroelectric properties. The renewed interest in the KTa1-xNbxO (KTN) mixed perovskite materials, especially in high quality thin films, is connected with their remarkable dielectric properties in the dilute compositions. Off-center Nb ions in the highly polarizable KTaO3 lattice provide a drastic increase in the dielectric peak, up to 20 times in comparison with the pure KTaO3 and KNbO3. The effects of the substrate and the symmetry-breaking defects on their vibration spectra were studied by micro-Raman spectroscopy. An anomalous residual intensity of the forbidden first-order scattering modes in the cubic paraelectric phase of the KTN films was connected with the formation of polar microregions even far above the bulk Tc. On the whole, the KTN film behavior shows the existence of specific defects enhancing the perovskite unit cell in the film so that the activity of off-center Nb ions increases in producing larger electric dipoles and extending the precursor phase above Tc. In diluted compositions with low Nb concentrations KTN materials exhibit formation of polar nano regions and relaxor like behavior. This behavior is analogous with

  10. Spectroscopic study of biologically active glasses

    NASA Astrophysics Data System (ADS)

    Szumera, M.; Wacławska, I.; Mozgawa, W.; Sitarz, M.

    2005-06-01

    It is known that the chemical activity phenomenon is characteristic for some inorganic glasses and they are able to participate in biological processes of living organisms (plants, animals and human bodies). An example here is the selective removal of silicate-phosphate glass components under the influence of biological solutions, which has been applied in designing glasses acting as ecological fertilizers of controlled release rate of the nutrients for plants. The structure of model silicate-phosphate glasses containing the different amounts of the glass network formers, i.e. Ca 2+ and Mg 2+, as a binding components were studied. These elements besides other are indispensable of the normal growth of plants. In order to establish the function and position occupied by the particular components in the glass structure, the glasses were examined by FTIR spectroscopy (with spectra decomposition) and XRD methods. It has been found that the increasing amount of MgO in the structure of silicate-phosphate glasses causes the formation of domains the structure of which changes systematically from a structure of the cristobalite type to a structure corresponding to forsterite type. Whilst the increasing content of CaO in the structure of silicate-phosphate glasses causes the formation of domains the structure of which changes from a structure typical for cristobalite through one similar to the structure of calcium orthophosphate, to a structure corresponding to calcium silicates. The changing character of domains structure is the reason of different chemical activity of glasses.

  11. Fluorescence spectroscopic studies of DNA dynamics

    SciTech Connect

    Scalettar, B.A.

    1987-04-01

    Random solvent induced motions of DNA are manifest as nanosecond torsional oscillations of the helix backbone, nanosecond through millisecond bending deformations and overall rotational and translational diffusion of the polymer. Fluorescence spectroscopy is used to study this spectrum of DNA motions while ethidium monoazide was covalently bounded. The steady state fluorescence depolarization data indicate that the covalent monoazide/DNA complex exhibits internal motions characterized by an average angular amplitude of 26 degrees confirming reports of fast torsional oscillations in noncovalent ethidium bromide/DNA systems. Data obtained by use of a new polarized photobleaching recovery technique (FPR) reflect both the rotational dynamics of the polymer and the reversible photochemistry of the dye. To isolate the reorientational motion of the DNA, the FPR experiments were ran in two modes that differ only in the polarization of the bleaching light. A quotient function constructed from the data obtained in these two modes monitors only the rotational component of the FPR recovery. In specific applications those bending deformations of long DNA molecules that have characteristic relaxation times on the order of 100 microseconds have been resolved. A fluorescence correlation technique that relates fluctuations in particle number to center-of-mass motion was used to measure translational diffusion on coefficients of the plasmid PBR322 and a short oligomeric DNA. A theory that describes angular correlation in systems exhibiting cyclic, biologically directed reorientation and random Brownian rotation is developed.

  12. Integrated Spectroscopic Studies of Anhydrous Sulfate Minerals

    NASA Technical Reports Server (NTRS)

    Lane, M. D.; Bishop, J. L.; Dyar, M. D.; Cloutis, E.; Forray, F. L.; Hiroi, T.

    2005-01-01

    Sulfates have been identified in Martian soils and bedrock and are emerging as an important indicator for aqueous activity on Mars. Sulfate minerals can form in a variety of low-temperature (evaporitic; chemical-weathering) and high-temperature (volcanic/fumarolic; hydrothermal) environments and their formational environments can range from alkaline to acidic. Although sulfates generally form in the presence of water, not all sulfates are hydrous or contain water in their structures. Many of these anhydrous sulfates (Dana group 28; Strunz class 67A) are minerals that form as accompanying phases to the main minerals in ore deposits or as replacement deposits in sedimentary rocks. However, some form from thermal decomposition of OH or H2O-bearing sulfates, such as from the reaction [1]: jarosite = yavapaiite + Fe2O3 + H2O. Where known, the stability fields of these minerals all suggest that they would be stable under martian surface conditions [2]. Thus, anhydrous sulfate minerals may contribute to martian surface mineralogy, so they must be well-represented in spectral libraries used for interpretation of the Martian surface. We present here the preliminary results of an integrated study of emittance, reflectance, and Mossbauer spectroscopy of a suite of wel-lcharacterized anhydrous sulfates.

  13. DAO Spectroscopic Study of Nova Cygni 1992

    NASA Astrophysics Data System (ADS)

    Garnavich, Peter M.

    1992-12-01

    The spectral development of Nova Cygni 1992 is being monitored at the Dominion Astrophysical Observatory. The brightest nova in over 15 years provides a rare opportunity to study, in detail, nova evolution from maximum to the late nebular stages. Our spectra during the early phases of the outburst had a resolution of 0.6 Angstroms while in the nebular phase the resolution ranged from 2 Angstroms to 4 Angstroms . The nova was observed at DAO on more than 40 nights in 1992. Our first spectrum was obtained near maximum light on February 22, 1992. It showed weak Hβ and Fe II emission lines with P-Cygni absorption components at -910 and -1670 km/s (IAUC 5457). During the early decline, the P-Cygni absorption complex spread blueward, eventually reaching -2900 km/s by the ides of March. Observations by IUE showed absorption troughs of UV lines extending to -2800 km/s even before maximum (IAUC 5456). This suggests that the apparent increase in the velocity of the diffuse-enhanced absorption is due to opacity effects, not a physical acceleration of the gas or the changing geometry of the expanding shells. The transition to the nebular phase occurred in late April, 1992. The emission lines were broad (FWHM of 2200 km/s) and contained as many as 10 velocity components. The temperature and density evolution of the major velocity components are estimated from diagnostic line ratios during the nebular stage. The similarity between Nova Cygni 1992 and V1500 Cyg suggested that the coronal line, [Fe X] 6374 Angstroms , might be present in the early nebular phase. The unusual shape and strength of the [O I] line at 6363 Angstroms added to this suspicion. In spectra taken 90 days after outburst, the [O I] 6300 Angstroms line was used to deconvolve the emission, but the contamination was found to be due to the Si II doublet 6347/71 Angstroms . Infrared observations indicated the onset of a coronal phase 200 days after maximum (IAUC 5612), and our data from this period are analyzed

  14. Mitochondrial Membrane Studies Using Impedance Spectroscopy with Parallel pH Monitoring

    PubMed Central

    Padmaraj, Divya; Pande, Rohit; Miller, John H.; Wosik, Jarek; Zagozdzon-Wosik, Wanda

    2014-01-01

    A biological microelectromechanical system (BioMEMS) device was designed to study complementary mitochondrial parameters important in mitochondrial dysfunction studies. Mitochondrial dysfunction has been linked to many diseases, including diabetes, obesity, heart failure and aging, as these organelles play a critical role in energy generation, cell signaling and apoptosis. The synthesis of ATP is driven by the electrical potential across the inner mitochondrial membrane and by the pH difference due to proton flux across it. We have developed a tool to study the ionic activity of the mitochondria in parallel with dielectric measurements (impedance spectroscopy) to gain a better understanding of the properties of the mitochondrial membrane. This BioMEMS chip includes: 1) electrodes for impedance studies of mitochondria designed as two- and four-probe structures for optimized operation over a wide frequency range and 2) ion-sensitive field effect transistors for proton studies of the electron transport chain and for possible monitoring other ions such as sodium, potassium and calcium. We have used uncouplers to depolarize the mitochondrial membrane and disrupt the ionic balance. Dielectric spectroscopy responded with a corresponding increase in impedance values pointing at changes in mitochondrial membrane potential. An electrical model was used to describe mitochondrial sample’s complex impedance frequency dependencies and the contribution of the membrane to overall impedance changes. The results prove that dielectric spectroscopy can be used as a tool for membrane potential studies. It can be concluded that studies of the electrochemical parameters associated with mitochondrial bioenergetics may render significant information on various abnormalities attributable to these organelles. PMID:25010497

  15. Spectroscopic studies of protein folding: Linear and nonlinear methods

    PubMed Central

    Serrano, Arnaldo L; Waegele, Matthias M; Gai, Feng

    2012-01-01

    Although protein folding is a simple outcome of the underlying thermodynamics, arriving at a quantitative and predictive understanding of how proteins fold nevertheless poses huge challenges. Therefore, both advanced experimental and computational methods are continuously being developed and refined to probe and reveal the atomistic details of protein folding dynamics and mechanisms. Herein, we provide a concise review of recent developments in spectroscopic studies of protein folding, with a focus on new triggering and probing methods. In particular, we describe several laser-based techniques for triggering protein folding/unfolding on the picosecond and/or nanosecond timescales and various linear and nonlinear spectroscopic techniques for interrogating protein conformations, conformational transitions, and dynamics. PMID:22109973

  16. A study on the impact of lithium-ion cell relaxation on electrochemical impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Barai, Anup; Chouchelamane, Gael H.; Guo, Yue; McGordon, Andrew; Jennings, Paul

    2015-04-01

    Lithium-ion (Li-ion) batteries are of great interest to the automotive industry due to their higher power and energy density, higher cell voltage, longer cycle life and lower self-discharge compared to other battery chemistries. Electrochemical impedance spectroscopy is a powerful tool employed to investigate the fundamental electrochemical reactions within a Li-ion battery cell, which relates to state of charge, internal temperature and state of health. Its effectiveness has established it as a core method to study electrochemical behaviour of batteries in both off-line and on-line applications. In this work it is shown that in addition to state of charge, internal temperature and state of health, the time period between the removal of an electrical load and the impedance measurement affects the results. The study of five commercially available cells of varying capacities and electrode chemistries show that, regardless of cell type, maximum impedance change takes place within the first 4 h of the relaxation period. The root cause of this impedance change has been discussed from an electrochemical perspective.

  17. Radiation impedance study of a capacitive micromachined ultrasonic transducer by finite element analysis.

    PubMed

    Bayram, Baris

    2015-08-01

    In this study, radiation impedance of a capacitive micromachined ultrasonic transducer composed of square-shaped membranes arranged in m × m configuration (m = 1 - 5) is investigated using finite element analysis (FEA) of a commercially available software package(ANSYS). Radiation impedance is calculated for immersed membranes operating in conventional and collapse modes. Individual membrane response within the multi-membrane configuration is analyzed, and excited modes and their effects on radiation impedance and the pressure spectra are reported. This FEA provides an accurate behavior of the acoustic coupling of a thin membrane in a multi-membrane configuration, and extends above the anti-resonance frequency. The first resonance frequency of the membrane is excited for m × m (m ≥ 3) configuration in conventional mode and for m × m (m ≥ 2) configuration in collapse mode. Therefore, this frequency is determined to be responsible for the adverse effects observed in radiation impedance and pressure spectrum. A membrane configuration, which is missing the central membrane from the full m × m configuration is proposed, and is investigated with the FEA. This study is beneficial for the design of precise transducers suited for biomedical applications. PMID:26328680

  18. AC Impedance Studies of Polymer Light-emitting Electrochemical Cells and Light-emitting Diodes

    NASA Astrophysics Data System (ADS)

    Li, Yongfang; Gao, Jun; Heeger, Alan J.; Yu, Gang; Cao, Yong

    1998-03-01

    The alternating current (ac) impedance of polymer light-emitting electrochemical cells (LECs) is studied and compared with that of polymer light-emitting diodes(LEDs) in the frequency range from 100 Hz to 5 M Hz. The device capacitance, resistance and interface characteristics are analyzed using the frequency dependence of the impedance and plots of the imaginary component of the impedance (Z") vs. the real part (Z'). At low bias voltages, polymer LEDs behave as pure capacitors whereas the polymer blend in the LEC exhibits an ionic conductivity contribution to the impedance. With dc bias higher than the energy gap of the semiconducting polymer (eV > Eg), the Z" vs. Z' plot of the LEC is a flattened semicircle, while that of LED is a semicircle with a small tail at low frequencies. In the LED, the capacitance is independent of voltages, the film resistance decreases as the bias voltage is increased in forward bias due to charge injection at higher voltages. In the LEC, the capacitance increases at voltages sufficient to induce electrochemical redox and doping near the electrodes. From this increase, the thickness of the i-layer of the p-i-n junction is estimated to approximately 0.8 of the film thickness (at the bias voltage of 3 V). Thus, in the LEC under operating conditions, the crossover region from p-type occupies most of the film thickness.

  19. Impedance study of tea with added taste compounds using conducting polymer and metal electrodes.

    PubMed

    Dhiman, Mopsy; Kapur, Pawan; Ganguli, Abhijit; Singla, Madan Lal

    2012-09-01

    In this study the sensing capabilities of a combination of metals and conducting polymer sensing/working electrodes for tea liquor prepared by addition of different compounds using an impedance mode in frequency range 1 Hz-100 KHz at 0.1 V potential has been carried out. Classification of six different tea liquor samples made by dissolving various compounds (black tea liquor + raw milk from milkman), (black tea liquor + sweetened clove syrup), (black tea liquor + sweetened ginger syrup), (black tea liquor + sweetened cardamom syrup), (black tea liquor + sweet chocolate syrup) and (black tea liquor + vanilla flavoured milk without sugar) using six different working electrodes in a multi electrode setup has been studied using impedance and further its PCA has been carried out. Working electrodes of Platinum (Pt), Gold (Au), Silver (Ag), Glassy Carbon (GC) and conducting polymer electrodes of Polyaniline (PANI) and Polypyrrole (PPY) grown on an ITO surface potentiostatically have been deployed in a three electrode set up. The impedance response of these tea liquor samples using number of working electrodes shows a decrease in the real and imaginary impedance values presented on nyquist plots depending upon the nature of the electrode and amount of dissolved salts present in compounds added to tea liquor/solution. The different sensing surfaces allowed a high cross-selectivity in response to the same analyte. From Principal Component Analysis (PCA) plots it was possible to classify tea liquor in 3-4 classes using conducting polymer electrodes; however tea liquors were well separated from the PCA plots employing the impedance data of both conducting polymer and metal electrodes. PMID:23035436

  20. Spectroscopic and dynamical studies of highly energized small polyatomic molecules

    SciTech Connect

    Field, R.W.; Silbey, R.J.

    1993-12-01

    The authors have initiated a program to perform spectroscopic and dynamic studies of small molecules. Large amplitude motions in excited acetylene were discussed along with plans to record the dispersed fluorescence (DF) and the stimulated emission pumping (SEP) spectra. SEP spectra were reported for the formyl radical. A Fourier transform spectrometer was discussed with respect to its ability to probe the structure of radicals. This instrument is capable of performing studies using various techniques such as magnetic rotation spectroscopy and sub-Doppler sideband-OODR Zeman (SOODRZ) spectroscopy.

  1. Comparative value of respiratory input and transfer impedances in field studies.

    PubMed

    Peslin, R; Pham, Q T; Teculescu, D; Gallina, C; Duvivier, C

    1987-01-01

    Total respiratory impedance was obtained from 4 to 30 Hz in 39 healthy males and in 140 iron miners by studying the relationship between transrespiratory pressure and mouth flow when forced oscillations were applied to the respiratory system in two different ways: by varying pressure at the mouth (input impedance, Zin); by varying pressure around the chest (transfer impedance, Ztr). Zin was characterized by the slope (S) and intercept (R0) of the resistance-frequency curve, by the resonant frequency (fn), and by total respiratory inertance (I) and compliance (C) obtained from the reactance. Transfer resistance and reactance curves were respectively analysed with a two-parameter (m1, m3) and a three-parameter (m0, m2, m4) equation. Significant correlations were found between impedance indices, particularly between m1 and both R0 (r = 0.931; p less than 0.001) and m2 (r = 0.739; p less than 0.001), and also between impedance indices and maximal expiratory flows. Nonsmoking miners (n = 40), compared to control nonsmokers (n = 16), had slightly lower maximal flows at high lung volumes (p less than 0.05) and higher values of m1 (p less than 0.001), R0, S, m3 (p less than 0.01) and m2 (p less than 0.05). In contrast, miners who smoked (n = 46) mainly differed from miners who did not smoke by lower flows at middle and low lung volumes (p less than 0.01) and larger m0 (p less than 0.01), m2 and m4 (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3593995

  2. Impedance spectroscopy studies in cobalt ferrite-reduced graphene oxide nanocomposite

    NASA Astrophysics Data System (ADS)

    Supriya, Sweety; Kumar, Sunil; Kar, Manoranjan

    2016-05-01

    (1-x)Cobalt ferrite-(x)reduced graphene oxidenanocomposites with x=0, 0.1, 0.2 and 0.3 were prepared by the ultrasonic method. The crystal symmetry modification due to reduced graphene oxide and cobalt ferrite interaction has been studied by employing the X-ray diffraction technique. Morphology of the samples was studied by the Field emission scanning electron microscopy (FE-SEM). Study on electrical properties of the cobalt ferrite-reduced graphene oxide nanocomposites explores the possible application of these composites as anode material. Impedance decreases with an increase in frequency as well as temperature, which supports an increase in ac electrical conductivity. The modified Debye relaxation model can explain the behavior of impedance in cobalt ferrite-reduced graphene oxide nanocomposites.

  3. The Origin, Composition and History of Comets from Spectroscopic Studies

    NASA Astrophysics Data System (ADS)

    Allamandola, L. J.

    1997-12-01

    A wealth of information essential to understanding the composition and physical structure of cometary ice and hence gain deep insight into the comet's origin and history, can be gleaned by carrying out a full range of spectroscopic studies on the returned sample. These studies ought to be among the first performed as they are generally non-destructive and will provide a broad data bank which will be crucial in planning subsequent analysis. Examples of the spectroscopic techniques along with relative sensitivities and transitions probed, are discussed. Different kind of "spectroscopy" is summarized, with emphasis placed on the kind of information each provides. Infrared spectroscopy should be the premier method of analysis as the mid-IR absorption spectrum of a substance contains more global information about the identity and structure of that material than any other property. In fact, the greatest strides in our understanding of the composition of interstellar ices (thought by many to be the primordial material from which comets have formed) have been taken during the past ten years or so because this was when high quality infrared spectra of the interstellar medium (ISM) first became available. The interpretation of the infrared spectra of mixtures, such as expected in comets, is often (not always) ambiguous. Consequently, a full range of other non-destructive, complementary spectroscopic measurements are required to fully characterize the material, to probe for substances for which the IR is not well suited and to lay the groundwork for future analysis. Given the likelihood that the icy component (including some of the organic and mineral phases) of the returned sample will be exceedingly complex, these techniques must be intensely developed over the next decade and then made ready to apply flawlessly to what will certainly be one of the most precious, and most challenging, samples ever analyzed.

  4. The Origin, Composition and History of Comets from Spectroscopic Studies

    NASA Technical Reports Server (NTRS)

    Allamandola, L. J.

    1997-01-01

    A wealth of information essential to understanding the composition and physical structure of cometary ice and hence gain deep insight into the comet's origin and history, can be gleaned by carrying out a full range of spectroscopic studies on the returned sample. These studies ought to be among the first performed as they are generally non-destructive and will provide a broad data bank which will be crucial in planning subsequent analysis. Examples of the spectroscopic techniques along with relative sensitivities and transitions probed, are discussed. Different kind of "spectroscopy" is summarized, with emphasis placed on the kind of information each provides. Infrared spectroscopy should be the premier method of analysis as the mid-IR absorption spectrum of a substance contains more global information about the identity and structure of that material than any other property. In fact, the greatest strides in our understanding of the composition of interstellar ices (thought by many to be the primordial material from which comets have formed) have been taken during the past ten years or so because this was when high quality infrared spectra of the interstellar medium (ISM) first became available. The interpretation of the infrared spectra of mixtures, such as expected in comets, is often (not always) ambiguous. Consequently, a full range of other non-destructive, complementary spectroscopic measurements are required to fully characterize the material, to probe for substances for which the IR is not well suited and to lay the groundwork for future analysis. Given the likelihood that the icy component (including some of the organic and mineral phases) of the returned sample will be exceedingly complex, these techniques must be intensely developed over the next decade and then made ready to apply flawlessly to what will certainly be one of the most precious, and most challenging, samples ever analyzed.

  5. Impedance Spectroscopy Study of Composite Thin Films of Hydrated Polyethylene Glycol

    SciTech Connect

    Al-Hamarneh, Ibrahim F.; Pedrow, Patrick D.; Goheen, Steven C.; Hartenstine, M. J.

    2007-05-01

    A polythelene glycol (PEG) polymer was synthesized using a dip coating procedure on 316L stainless steel (SS) substrate pre coated by radio frequency RF inductively coupled plasma polymerization with di (ethylene glycol) vinyl ether (EO2V) monomer that was used as a primer coat. The primer and PEG composite film was studied with profilometer, visible-light microscope, scanning electron microscope (SEM) and a tape test to evaluate thickness, stability, morphology and adhesion. Response of the PEG composite film to an AC electric perturbation was studied as a function of hydration state using impedance spectroscopy (IS). A resistor/capacitor network was used to interpret the impedance spectra. The capacitance of the PEG film decreased with an exponentially decaying term as dehydration progressed. PEG film capacitance decay was consistent with a model describing water molecules diffusing through the PEG film.

  6. Impedance Spectroscopy Study of Composite Thin Films of Hydrated Polyethylene Glycol

    SciTech Connect

    Al-Hamarneh, Ibrahim F.; Pedrow, Patrick D.; Goheen, Steven C.; Hartenstine, M. J.

    2007-10-01

    A polyethylene glycol (PEG) polymer was synthesized using a dip coating procedure on 316L stainless steel (SS) substrate pre-coated with a primer that consisted of radio frequency RF inductively coupled plasma-polymerized di (ethylene glycol) vinyl ether (EO2V). The primer and PEG composite film was studied with profilometer, optical microscope, scanning electron microscope (SEM), and a tape test to evaluate thickness, coverage, morphology, and adhesion, respectively. Response of the PEG composite film to an applied AC voltage was studied as a function of hydration state using impedance spectroscopy (IS). A resistor/capacitor network was used to interpret the impedance spectra. Electrical capacitance of the PEG film decreased with an exponentially decaying term as dehydration progressed. PEG film capacitance decay was consistent with a model describing water molecules diffusing through the PEG film.

  7. Electrochemical cell design for the impedance studies of chlorine evolution at DSA(®) anodes.

    PubMed

    Silva, J F; Dias, A C; Araújo, P; Brett, C M A; Mendes, A

    2016-08-01

    A new electrochemical cell design suitable for the electrochemical impedance spectroscopy (EIS) studies of chlorine evolution on Dimensionally Stable Anodes (DSA(®)) has been developed. Despite being considered a powerful tool, EIS has rarely been used to study the kinetics of chlorine evolution at DSA anodes. Cell designs in the open literature are unsuitable for the EIS analysis at high DSA anode current densities for chlorine evolution because they allow gas accumulation at the electrode surface. Using the new cell, the impedance spectra of the DSA anode during chlorine evolution at high sodium chloride concentration (5 mol dm(-3) NaCl) and high current densities (up to 140 mA cm(-2)) were recorded. Additionally, polarization curves and voltammograms were obtained showing little or no noise. EIS and polarization curves evidence the role of the adsorption step in the chlorine evolution reaction, compatible with the Volmer-Heyrovsky and Volmer-Tafel mechanisms. PMID:27587166

  8. Electrical impedance measurements in the arm and the leg during a thirty day bed rest study

    NASA Technical Reports Server (NTRS)

    Cardus, David; Jaweed, Mazher; McTaggart, Wesley

    1995-01-01

    The need to detect, follow, and understand the effects of gravity on body fluid distribution is a constant stimulus to the quest for new techniques in this area of research. One of these techniques is electrical bioimpedance spectroscopy (BIS). Although not new, this is a technique whose applications to biomedical research are fairly recent. What is new is the development of instrumentation that has made practical the use of impedance spectroscopy in the biomedical setting, particularly in studies involving human subjects. The purpose of this paper is to report impedance spectroscopy observations made on a subject who was submitted to bed rest for a period of thirty days. These observations were made as part of a study on muscle atrophy during a thirty day head down bed rest. Since bed rest studies are very costly in human and financial terms, and technically difficult to realize, we felt that even though the present study deals only with a single case it was worthy of reporting because it illustrates kinds of questions impedance spectroscopy may help to answer in microgravity research.

  9. Indentation device for in situ Raman spectroscopic and optical studies

    NASA Astrophysics Data System (ADS)

    Gerbig, Y. B.; Michaels, C. A.; Forster, A. M.; Hettenhouser, J. W.; Byrd, W. E.; Morris, D. J.; Cook, R. F.

    2012-12-01

    Instrumented indentation is a widely used technique to study the mechanical behavior of materials at small length scales. Mechanical tests of bulk materials, microscopic, and spectroscopic studies may be conducted to complement indentation and enable the determination of the kinetics and physics involved in the mechanical deformation of materials at the crystallographic and molecular level, e.g., strain build-up in crystal lattices, phase transformations, and changes in crystallinity or orientation. However, many of these phenomena occurring during indentation can only be observed in their entirety and analyzed in depth under in situ conditions. This paper describes the design, calibration, and operation of an indentation device that is coupled with a Raman microscope to conduct in situ spectroscopic and optical analysis of mechanically deformed regions of Raman-active, transparent bulk material, thin films or fibers under contact loading. The capabilities of the presented device are demonstrated by in situ studies of the indentation-induced phase transformations of Si thin films and modifications of molecular conformations in high density polyethylene films.

  10. Electrochemical impedance spectroscopy studies of lithium diffusion in doped manganese oxide

    SciTech Connect

    Johnson, B.J.; Doughty, D.H.; Voigt, J.A.; Boyle, T.J.

    1996-06-01

    Cathode performance is critical to lithium ion rechargeable battery performance; effects of doping lithium manganese oxide cathode materials on cathode performance are being investigated. In this paper, Li diffusion in Al-doped LiMn{sub 2}O{sub 4} was studied and found to be controlled by the quantity of Al dopant. Electrochemical cycling was conducted at 0.5mA/cm{sub 2}; electrochemical impedance spectra were taken at open circuit potential, with impedance being measured at 65 kHz-0.01 Hz. As the Al dopant level was increased, the Li diffusion rate decreased; this was attributed to the decreased lattice parameter of the doped oxide.

  11. A Study of Concrete Slab Damage Detection Based on the Electromechanical Impedance Method

    PubMed Central

    Hu, Xianyan; Zhu, Hongping; Wang, Dansheng

    2014-01-01

    Piezoelectric lead zirconate titanate (PZT) is being gradually applied into practice as a new intelligent material for structural health monitoring. In order to study the damage detection properties of PZT on concrete slabs, simply supported reinforced concrete slabs with piezoelectric patches attached to their surfaces were chosen as the research objects and the Electromechanical Impedance method (EMI) was adopted for research. Five kinds of damage condition were designed to test the impedance values at different frequency bands. Consistent rules are found by calculation and analysis. Both the root mean square deviation (RMSD) and the correlation coefficient deviation (CCD) damage indices are capable of detecting the structural damage. The newly proposed damage index Ry/Rx can also predict the changes well. The numerical and experimental studies verify that the Electromechanical Impedance method can accurately predict changes in the amount of damage in reinforced concrete slabs. The damage index changes regularly with the distance of damages to the sensor. This relationship can be used to determine the damage location. The newly proposed damage index Ry/Rx is accurate in determining the damage location. PMID:25341438

  12. Novel dipodal Schiff base compounds: Synthesis, characterization and spectroscopic studies

    NASA Astrophysics Data System (ADS)

    Obali, Aslihan Yilmaz; Ucan, Halil Ismet

    2015-02-01

    Two novel dipodal Schiff base compounds 1,2-benzyloxy-bis-[2-(benzylideneamino)phenol, L1 and 1,2-benzyloxy-bis[3-(benzylideneamino)pyridine], L2 were synthesized. Their sensing actions were confirmed by UV-Vis absorbance and emission spectroscopic studies in presence of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Sn(II), Cd(II) and Pb(II) in methanol medium (1 × 10-4 M). It was found that the dipodal compounds can selectively bind to Cu(II) and Pb(II) metal ions with a significant change in its emission and absorption spectra, while the addition of other metal ions (Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Sn(II), Cd(II) and Pb(II)) produces insignificant or minor changes. The host-guest complexes formed were determined by Job's plot method. As a chemosensor, L1 and L2 dipodal Schiff base compounds shows a specific selectivity towards Cu(II) and Pb(II) ions in according to all spectroscopic data.

  13. The first spectroscopic study of southern binary:HD 53570

    NASA Astrophysics Data System (ADS)

    Sürgit, D.

    2016-03-01

    In this study, I present the first analysis of spectroscopic observations of southern detached eclipsing binary star HD 53570. The spectroscopic observations of HD 53570 was made at the Sutherland Station of the South African Astronomical Observatory (SAAO) in 2013 and 2014. Radial velocities (RVs) of the components of HD 53570 were determined by cross-correlation technique (CCT). The Hβ (4861.36 Å) lines of the components of HD 53570 were chosen as the most suitable lines for reliable RV measurements. The resulting orbital elements of HD 53570 is calculated as, a1 sin i = 0.0258±0.0005 AU, a2 sin i = 0.0228±0.0005 AU, M1 sin3i = 1.035±0.046 M⊙ and M2 sin3i = 1.167±0.050 M⊙. The radial velocity models of HD 53570 give the close binaries mass ratio as 1.13±0.07.

  14. Impedance Mismatch study between the Microwave Generator and the PUPR Plasma Machine

    SciTech Connect

    Gaudier, Jorge R.; Castellanos, Ligeia; Encarnacion, Kabir; Zavala, Natyaliz; Rivera, Ramon; Farahat, Nader; Leal, Edberto

    2006-12-04

    Impedance mismatch inside the connection from the microwave power generator to the plasma machine is studied. A magnetron power generator transmits microwaves of 2.45 GHz and variable power from 50W to 5000W, through a flexible rectangular waveguide to heat plasma inside a Mirror Cusp devise located at the Polytechnic University of Puerto Rico. Before the production of plasma, the residual gas of the devise must be extracted by a vacuum system (5Torr or better), then Argon gas is injected to the machine. The microwaves heat the Argon ions to initiate ionization and plasma is produced. A dielectric wall is used inside the rectangular waveguide to isolate the plasma machine and maintain vacuum. Even though the dielectric will not block the wave propagation, some absorption of microwaves will occur. This absorption will cause reflection, reducing the efficiency of the power transfer. Typically a thin layer of Teflon is used, but measurements using this dielectric show a significant reflection of power back to the generator. Due to the high-power nature of the generator (5KW), this mismatch is not desirable. An electromagnetic field solver based on the Finite Difference Time Domain Method(FDTD) is used to model the rectangular waveguide connection. The characteristic impedance of the simulation is compared with the analytical formula expression and a good agreement is obtain. Furthermore the Teflon-loaded guide is modeled using the above program and the input impedance is computed. The reflection coefficient is calculated based on the transmission line theory with the characteristic and input impedances. Based on the simulation results it is possible to optimize the thickness, shape and dielectric constant of the material, in order to seal the connection with a better match.

  15. Study of the Dynamics of Transcephalic Cerebral Impedance Data during Cardio-Vascular Surgery

    NASA Astrophysics Data System (ADS)

    Atefi, S. R.; Seoane, F.; Lindecrantz, K.

    2013-04-01

    Postoperative neurological deficits are one of the risks associated with cardio vascular surgery, necessitating development of new techniques for cerebral monitoring. In this study an experimental observation regarding the dynamics of transcephalic Electrical Bioimpedance (EBI) in patients undergoing cardiac surgery with and without extracorporeal circulation (ECC) was conducted to investigate the potential use of electrical Bioimpedance for cerebral monitoring in cardio vascular surgery. Tetrapolar transcephalic EBI measurements at single frequency of 50 kHz were recorded prior to and during cardio vascular surgery. The obtained results show that the transcephalic impedance decreases in both groups of patients as operation starts, however slight differences in these two groups were also observed with the cerebral impedance reduction in patients having no ECC being less common and not as pronounced as in the ECC group. Changes in the cerebral impedance were in agreement with changes of haematocrit and temperature. The origin of EBI changes is still unexplained however these results encourage us to continue investigating the application of electrical bioimpedance cerebral monitoring clinically.

  16. Experimental Study of Radiation Impedance with Effect of Reflected Wave from Sonar Dome

    NASA Astrophysics Data System (ADS)

    Jungsoon Kim,; Moojoon Kim,; Kanglyeol Ha,; Heeseon Seo,; Cheeyong Joh,

    2010-07-01

    The radiation impedance of arrayed vibrators is analyzed experimentally when the array has a reflector. To verify the effect of the reflector, the radiation impedance with the reflector was calculated. To estimate the radiation impedance change, the input impedance of the vibrator was calculated using an equivalent circuit model. The input impedance was dependant on the location of the vibrators. The experimental results show a similar tendency to the theoretical results. It is noted that the equivalent circuit model for theoretical analysis is useful for estimating the radiation impedance change caused by the reflected wave.

  17. Combined spectroscopic and quantum chemical studies of ezetimibe

    NASA Astrophysics Data System (ADS)

    Prajapati, Preeti; Pandey, Jaya; Shimpi, Manishkumar R.; Srivastava, Anubha; Tandon, Poonam; Velaga, Sitaram P.; Sinha, Kirti

    2016-12-01

    Ezetimibe (EZT) is a hypocholesterolemic agent used for the treatment of elevated blood cholesterol levels as it lowers the blood cholesterol by blocking the absorption of cholesterol in intestine. Study aims to combine experimental and computational methods to provide insights into the structural and vibrational spectroscopic properties of EZT which is important for explaining drug substance physical and biological properties. Computational study on molecular properties of ezetimibe is presented using density functional theory (DFT) with B3LYP functional and 6-311++G(d,p) basis set. A detailed vibrational assignment has been done for the observed IR and Raman spectra of EZT. In addition to the conformational study, hydrogen bonding and molecular docking studies have been also performed. For conformational studies, the double well potential energy curves have been plotted for the rotation around the six flexible bonds of the molecule. UV absorption spectrum was examined in methanol solvent and compared with calculated one in solvent environment (IEF-PCM) using TD-DFT/6-31G basis set. HOMO-LUMO energy gap of both the conformers have also been calculated in order to predict its chemical reactivity and stability. The stability of the molecule was also examined by means of natural bond analysis (NBO) analysis. To account for the chemical reactivity and site selectivity of the molecules, molecular electrostatic potential (MEPS) map has been plotted. The combination of experimental and calculated results provide an insight into the structural and vibrational spectroscopic properties of EZT. In order to give an insight for the biological activity of EZT, molecular docking of EZT with protein NPC1L1 has been done.

  18. [Spectroscopic studies on transition metal ions in colored diamonds].

    PubMed

    Meng, Yu-Fei; Peng, Ming-Sheng

    2004-07-01

    Transition metals like nickel, cobalt and iron have been often used as solvent catalysts in high pressure high temperature (HPHT) synthesis of diamond, and nickel and cobalt ions have been found in diamond lattice. Available studies indicated that nickel and cobalt ions could enter the lattice as interstitial or substitutional impurities and form complexes with nitrogen. Polarized microscopy, SEM-EDS, EPR, PL and FTIR have been used in this study to investigate six fancy color natural and synthetic diamonds in order to determine the spectroscopic characteristics and the existing forms of transition metal ions in colored diamond lattice. Cobalt-related optical centers were first found in natural chameleon diamonds, and some new nickel and cobalt-related optical and EPR centers have also been detected in these diamond samples. PMID:15766067

  19. A Spectroscopic-Based Laboratory Experiment for Protein Conformational Studies

    ERIC Educational Resources Information Center

    Ramos, Carlos Henrique I.

    2004-01-01

    This article describes a practical experiment for teaching basic spectroscopic techniques to introduce the topic of protein conformational change to students in the field of molecular biology, biochemistry, or structural biology. The spectroscopic methods employed in the experiment are absorbance, for protein concentration measurements, and…

  20. Infrared spectroscopic study of sputtered tungsten oxide films

    SciTech Connect

    Paul, J.L.; Lassegues, J.C. )

    1993-10-01

    Recent infrared and Raman spectroscopic studies of various tungsten oxide films concluded either the formation of W=O terminal bonds or the transformation of such bonds into W-OH groups upon proton insertion. The infrared transmission and reflection spectra of bleached and colored sputtered films were reinvestigated in order to resolve the previous contradictory interpretations and for better insight into the mechanism of electrochromism at the molecular level. The new results confirm the first interpretation and allow us to show that H[sup +] or Li[sup +] insertion creates shorter ([approximately]1.7[angstrom]) and longer ([approximately]2 [angstrom]) W-O bonds around the W[sup 5+] centers. These results are in agreement with the concepts of small polaron and of intervalence charge transfer mechanism. They illustrate the local lattice distortion around a W[sup 5+] site. Aging of the initial films has also been followed and characterized by H/D in situ isotopic exchange.

  1. Spectroscopic study of Gd nanostructures quantum confined in Fe corrals

    SciTech Connect

    Cao, R. X.; Sun, L.; Miao, B. F.; Li, Q. L.; Zheng, C.; Wu, D.; You, B.; Zhang, W.; Han, P.; Bader, S. D.; Zhang, W. Y.; Ding, H. F.

    2015-07-10

    Low dimensional nanostructures have attracted attention due to their rich physical properties and potential applications. The essential factor for their functionality is their electronic properties, which can be modified by quantum confinement. Here the electronic states of Gd atom trapped in open Fe corrals on Ag(111) were studied via scanning tunneling spectroscopy. A single spectroscopic peak above the Fermi level is observed after Gd adatoms are trapped inside Fe corrals, while two peaks appear in empty corrals. The single peak position is close to the higher energy peak of the empty corrals. These findings, attributed to quantum confinement of the corrals and Gd structures trapped inside, are supported by tight-binding calculations. As a result, this demonstrates and provides insights into atom trapping in open corrals of various diameters, giving an alternative approach to modify the properties of nano-objects.

  2. Molecular spectroscopic study for suggested mechanism of chrome tanned leather.

    PubMed

    Nashy, Elshahat H A; Osman, Osama; Mahmoud, Abdel Aziz; Ibrahim, Medhat

    2012-03-01

    Collagen represents the structural protein of the extracellular matrix, which gives strength of hides and/or skin under tanning process. Chrome tan is the most important tanning agent all over the world. The methods for production of leather evolved over several centuries as art and engineering with little understanding of the underlying science. The present work is devoted to suggest the most probable mechanistic action of chrome tan on hide proteins. First the affect of Cr upon hide protein is indicated by the studied mechanical properties. Then the spectroscopic characterization of the hide protein as well as chrome tanned leather was carried out with Horizontal Attenuated Total Reflection (HATR) FT-IR. The obtained results indicate how the chromium can attached with the active sites of collagen. Molecular modeling confirms that chromium can react with amino as well as carboxylate groups. Four schemes were obtained to describe the possible interactions of chrome tan with hide proteins. PMID:22225606

  3. Spectroscopic study of photo and thermal destruction of riboflavin

    NASA Astrophysics Data System (ADS)

    Astanov, Salikh; Sharipov, Mirzo Z.; Fayzullaev, Askar R.; Kurtaliev, Eldar N.; Nizomov, Negmat

    2014-08-01

    Influence of temperature and light irradiation on the spectroscopic properties of aqueous solutions of riboflavin was studied using linear dichroism method, absorption and fluorescence spectroscopy. It was established that in a wide temperature range 290-423 K there is a decline of absorbance and fluorescence ability, which is explained by thermodestruction of riboflavin. It is shown that the proportion of molecules, which have undergone degradation, are in the range of 4-28%, and depends on the concentration and quantity of temperature effects. Introduction of hydrochloric and sulfuric acids, as well as different metal ions leads to an increase in the photostability of riboflavin solutions by 2-2.5 times. The observed phenomena are explained by the formation protonation form of riboflavin and a complex between the metal ions and oxygen atoms of the carbonyl group of riboflavin, respectively.

  4. Raman spectroscopic study of "The Malatesta": a Renaissance painting?

    PubMed

    Edwards, Howell G M; Vandenabeele, Peter; Benoy, Timothy J

    2015-02-25

    Raman spectroscopic analysis of the pigments on an Italian painting described as a "Full Length Portrait of a Gentleman", known also as the "Malatesta", and attributed to the Renaissance period has established that these are consistent with the historical research provenance undertaken earlier. Evidence is found for the early 19th Century addition of chrome yellow to highlighted yellow ochre areas in comparison with a similar painting executed in 1801 by Sir Thomas Lawrence of John Kemble in the role of Hamlet, Prince of Denmark. The Raman data are novel in that no analytical studies have previously been made on this painting and reinforces the procedure whereby scientific analyses are accompanied by parallel historical research. PMID:25194320

  5. Spectroscopic Capabilities of XMM for Stellar Coronal Studies

    NASA Astrophysics Data System (ADS)

    Pallavicini, R.

    The turn of the millennium will be a marvelous time for X-ray astronomy with the launch of powerful missions such as AXAF, XMM, and ASTRO-E. Stellar coronae, with their spectra rich in emission lines, will be primary targets to exploit the spectroscopic capabilities of these missions. In particular, the CCD cameras and reflection gratings on XMM will allow us to address a number of key questions in stellar coronal physics. The capabilities of XMM for the study of stellar coronae are illustrated by means of simulations of EPIC and RGS spectra for a variety of typical stellar coronal sources. The mission time-line and the policy for accessing the data are also briefly illustrated.

  6. Molecular spectroscopic study for suggested mechanism of chrome tanned leather

    NASA Astrophysics Data System (ADS)

    Nashy, Elshahat H. A.; Osman, Osama; Mahmoud, Abdel Aziz; Ibrahim, Medhat

    2012-03-01

    Collagen represents the structural protein of the extracellular matrix, which gives strength of hides and/or skin under tanning process. Chrome tan is the most important tanning agent all over the world. The methods for production of leather evolved over several centuries as art and engineering with little understanding of the underlying science. The present work is devoted to suggest the most probable mechanistic action of chrome tan on hide proteins. First the affect of Cr upon hide protein is indicated by the studied mechanical properties. Then the spectroscopic characterization of the hide protein as well as chrome tanned leather was carried out with Horizontal Attenuated Total Reflection (HATR) FT-IR. The obtained results indicate how the chromium can attached with the active sites of collagen. Molecular modeling confirms that chromium can react with amino as well as carboxylate groups. Four schemes were obtained to describe the possible interactions of chrome tan with hide proteins.

  7. A detailed spectroscopic study of an Italian fresco

    SciTech Connect

    Barilaro, Donatella; Crupi, Vincenza; Majolino, Domenico; Barone, Germana; Ponterio, Rosina

    2005-02-15

    In the present work we characterized samples of plasters and pictorial layers taken from a fresco in the Acireale Cathedral. The fresco represents the Coronation of Saint Venera, patron saint of this Ionian town. By performing a detailed spectroscopic analysis of the plaster preparation layer by Fourier-transform infrared (FTIR) spectroscopy and x-ray diffraction (XRD), and of the painting layer by FTIR and confocal Raman microspectroscopy, scanning electron microscopy+energy dispersive x-ray spectroscopy, and XRD, we were able to identify the pigments and the binders present. In particular, Raman investigation was crucial to the characterization of the pigments thanks to the high resolution of the confocal apparatus used. It is worth stressing that the simultaneous use of complementary techniques was able to provide more complete information for the conservation of the artifact we studied.

  8. Spectroscopic and quantum chemical studies on 4-acryloyl morpholine

    NASA Astrophysics Data System (ADS)

    Arjunan, V.; Rani, T.; Santhanalakshmi, K.; Mohan, S.

    2011-09-01

    Fourier transform infrared (FTIR) and FT-Raman spectra have been recorded and an extensive spectroscopic investigations have been carried out on 4-acryloyl morpholine (4AM). Theoretical quantum chemical studies have also been performed. From the ab initio and DFT analysis using HF, B3LYP and B3PW91 methods with 6-31G(d,p) and 6-311G++(d,p) basis sets the energies, structural, thermodynamical and vibrational characteristics of the compound were determined. The energy difference between the chair equatorial and chair axial conformers of 4AM have been calculated by density functional theory (DFT) method. The optimized geometrical parameters, theoretical wavenumbers and thermodynamic properties of the molecule are compared with the experimental values. The effect of acryloyl group on the characteristic frequencies of the morpholine ring has been analysed. The mixing of the fundamental modes with the help of potential energy distribution (PED) through normal co-ordinate analysis has been discussed.

  9. Ultrasonic and spectroscopic studies on photoactivation of euglena

    NASA Astrophysics Data System (ADS)

    Saito, Mitsunori; Morita, Shin

    2006-12-01

    We studied the effect of the irradiation wavelength on the activity of photosynthetic euglena. The ultrasonic manipulation technique was used for both the activity evaluation and the movement restriction in the spectral measurements. Euglenas that had been preserved in darkness became inactive, and accordingly most of them were trapped by the ultrasonic standing wave (0.8mW/mm2). However, when they were exposed to light of 500 or 700nm wavelength (0.13W/m2), they became active enough to escape from the trapping. By contrast, irradiation at 550, 600, or 650nm wavelength had no effect on their activity. Spectroscopic measurements, which used to be difficult for locomotive microorganisms, were conducted successfully by trapping euglena at a node of the ultrasonic standing wave. The absorption bands were observed at around 500 or 700nm, which corresponded to the irradiation wavelengths that activated euglena.

  10. Spectroscopic study of Gd nanostructures quantum confined in Fe corrals

    DOE PAGESBeta

    Cao, R. X.; Sun, L.; Miao, B. F.; Li, Q. L.; Zheng, C.; Wu, D.; You, B.; Zhang, W.; Han, P.; Bader, S. D.; et al

    2015-07-10

    Low dimensional nanostructures have attracted attention due to their rich physical properties and potential applications. The essential factor for their functionality is their electronic properties, which can be modified by quantum confinement. Here the electronic states of Gd atom trapped in open Fe corrals on Ag(111) were studied via scanning tunneling spectroscopy. A single spectroscopic peak above the Fermi level is observed after Gd adatoms are trapped inside Fe corrals, while two peaks appear in empty corrals. The single peak position is close to the higher energy peak of the empty corrals. These findings, attributed to quantum confinement of themore » corrals and Gd structures trapped inside, are supported by tight-binding calculations. As a result, this demonstrates and provides insights into atom trapping in open corrals of various diameters, giving an alternative approach to modify the properties of nano-objects.« less

  11. Spectroscopic study of the peculiar galaxy IC 883

    NASA Astrophysics Data System (ADS)

    Yakovleva, V. A.; Merkulova, O. A.; Karataeva, G. M.; Shalyapina, L. V.; Yablokova, N. V.; Burenkov, A. N.

    2016-04-01

    We analyze new optical spectroscopic observations obtained at the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences with the SCORPIO focal reducer (in the modes of a Fabry-Perot interferometer (FPI) and long-slit spectroscopy) and the Multi-Pupil Fiber Spectrograph for the galaxy IC 883. We have confirmed that the main body of the galaxy rotates around its minor axis. The positions of the dynamical axes of the stellar and gaseous components have been found to differ by ~10°. The velocities in the SE tail do not correspond to the circular rotation around the galaxy's minor axis. This structure is probably a fragment of an unwound curved spiral arm. Regions with high velocity dispersions and peculiarities in the velocity fields have been found along the minor axis. Our study of the age and metallicity of the galaxy's stellar population has shown that the mean values of these parameters in the stellar disk, except for the central region ( r ≤ 5"), are ≈1 Gyr and ≈-0.4 dex, respectively. Both young (2-5 × 108 yr) and old (5-10 × 109 yr) stellar populations are present in the circumnuclear region. Our analysis of the spectroscopic data for the bright feature 8" south of the nucleus coincident in position with a compact X-ray source has shown that this is apparently a dwarf galaxy or a remnant of a companion galaxy. Our FPI observations in the Hα emission line and direct images have revealed a region of ionized gas that together with the already known structures along the minor axis forms a clumpy tidal structure of ionized gas pulled from the companion galaxy. The results of our study confirm the previously proposed hypothesis that the observed peculiar structures were formed by the merger of two galaxies. However, it can be said that IC 883 does not belong to the class of polar-ring galaxies.

  12. Electron Impedances

    SciTech Connect

    P Cameron

    2011-12-31

    It is only recently, and particularly with the quantum Hall effect and the development of nanoelectronics, that impedances on the scale of molecules, atoms and single electrons have gained attention. In what follows the possibility that characteristic impedances might be defined for the photon and the single free electron is explored is some detail, the premise being that the concepts of electrical and mechanical impedances are relevant to the elementary particle. The scale invariant quantum Hall impedance is pivotal in this exploration, as is the two body problem and Mach's principle.

  13. Thermoporometry and impedance analysis to study dynamics of water and polymer present in hydrogel.

    PubMed

    Selestin Raja, I; Nishad Fathima, Nishter

    2015-01-01

    Though various conventional methods are available to explore hydrogels, they have drawbacks such as analysis in solid state and failure to give insights into individual components of hydrogel viz. water (dispersion medium) and hydrophilic polymers (dispersed phase). The combined study of porosity and dielectric nature of hydrogel succeeds, in this context, as it investigates both the components individually. In this study, we have taken well-known hydrogel system gelatin-polyvinyl alcohol (PVA) cross linked with genipin. Thermoporometry has been used to investigate the state of water and porosity whereas Alternative Current (AC) impedance analysis has been used to study about nature of polymers through dielectric properties in hydrogel. The influence of physic-chemical properties was examined with SEM and in vitro drug release using catechin. The study revealed that increasing concentration of PVA to gelatin has retained excessive bound water molecules exhibiting high polarity in each polymeric component. Further, it is shown that reduction in pore size and high reactivity with drug molecules have led to lower initial release and increase total amount of release. We conclude that non-conventional methods such as thermoporometry and AC impedance analysis yield more valuable information about hydrogel, which can aid in designing appropriate biomaterial for intended drug release. PMID:25199869

  14. Ensemble averaged surface normal impedance of material using an in-situ technique: preliminary study using boundary element method.

    PubMed

    Otsuru, Toru; Tomiku, Reiji; Din, Nazli Bin Che; Okamoto, Noriko; Murakami, Masahiko

    2009-06-01

    An in-situ measurement technique of a material surface normal impedance is proposed. It includes a concept of "ensemble averaged" surface normal impedance that extends the usage of obtained values to various applications such as architectural acoustics and computational simulations, especially those based on the wave theory. The measurement technique itself is a refinement of a method using a two-microphone technique and environmental anonymous noise, or diffused ambient noise, as proposed by Takahashi et al. [Appl. Acoust. 66, 845-865 (2005)]. Measured impedance can be regarded as time-space averaged normal impedance at the material surface. As a preliminary study using numerical simulations based on the boundary element method, normal incidence and random incidence measurements are compared numerically: results clarify that ensemble averaging is an effective mode of measuring sound absorption characteristics of materials with practical sizes in the lower frequency range of 100-1000 Hz, as confirmed by practical measurements. PMID:19507960

  15. Intergrain connectivity of MgB{sub 2} ceramics studied by impedance analysis

    SciTech Connect

    Wang, C. C.; Wang, C.; Zeng, R.; Dou, S. X.

    2010-07-15

    First, by using of the conventional Rowell analysis, we demonstrated that the addition of nano BN particles can effectively eliminate MgO and pores in MgB{sub 2} resulting in a very high density and good connectivity of BN-doped MgB{sub 2}. Then, another method--low-frequency dielectric impedance analysis--was introduced to characterize the properties of the grain boundaries of MgB{sub 2}. A comparative impedance study was performed in the frequency range from 100 Hz to 100 MHz on pure and nano BN-doped MgB{sub 2}. The study revealed some following interesting results: (1) a dielectric resonance around frequency of 10{sup 8} in both samples was observed, which was argued to be related to an inductance-capacitance and (2) the pure sample has two dielectric relaxations originating from intergrains, while the doped sample has only one intergranular contribution. This convinces that the electric connectivity of the doped sample is really improved by the addition of nano BN particles. Our results indicate that dielectric technique may be a useful tool to characterize the grain boundary properties and grain boundary-related properties of MgB{sub 2}.

  16. Using two-dimensional impedance maps to study weak scattering in sparse random media.

    PubMed

    Luchies, Adam C; Oelze, Michael L

    2016-04-01

    Impedance maps (ZMs) have been proposed as a tool for modeling acoustic properties of tissue microstructure. Three-dimensional (3D) ZMs are constructed from a series of adjacent histological tissue slides that have been stained to emphasize acoustic impedance structures. The power spectrum of a 3DZM can be related to the ultrasound backscatter coefficient, which can be further reduced to a form factor. The goal of this study is to demonstrate the ability to estimate form factors using two-dimensional (2D) ZMs instead of 3DZMs, which have reduced computational and financial cost. The proposed method exploits the properties of isotropic media to estimate the correlation coefficient from slices before estimating the 3D volume power spectrum. Simulated sparse collections of objects were used to study the method by comparing the results obtained using 2DZMs to those predicted by theory. 2DZM analysis was conducted on normal rabbit liver histology and compared to 3DZM analysis of the same histology. The mean percent error between effective scatterer diameter estimates from 2DZMs and 3DZMs of rabbit liver histology was <10% when using three 2DZMs. The results suggest that 2DZMs are a feasible alternative to 3DZMs when estimating form factors for sparse collections of objects. PMID:27106304

  17. Impedance studies of Ni/Cd and Ni/H cells using the cell case as reference electrode

    NASA Technical Reports Server (NTRS)

    Reid, Margaret A.

    1989-01-01

    Many impedance studies were carried out on Ni electrodes and Ni/Cd and Ni/H batteries. In order for impedance to become a diagnostic tool, accurate and reproducible measurements must be made, and some way of separating the contributions of the individual electrodes must be found. Using the PAR and the Solartron impedance equipment, studies have found that consistent measurements can be made if the cells or electrodes are equilibrated at the voltage of interest. In the charged state, equilibration times required are short, on the order of a few hours or less, but the equilibration time required becomes progessively longer as the voltage is lowered. The cell case can be used as a reference electrode during impedance measurements. The voltage of the case with respect to the electrodes is unimportant provided that it does not change appreciably during the course of the measurement. Measurements were made with several uncycled Ni/Cd cells, one from a lot which was known to have faulty Cd electrodes and another from a lot which showed excellent cycle life and presumably had good Cd electrodes. The impedances of the Ni electrodes vs. the case were similar, while the impedance of the poor Cd electrodes vs. the case. A 50 AH Ni/H cell was also investigated. After subtraction of the ohmic resistances, the sums of the impedances of the individual electrodes were very close to the impedance of the total cell. This indicates that the method is valid for examining the characteristics of the individual electrodes in situ.

  18. EPR Spectroscopic Studies of [FeFe]-Hydrogenase Maturation

    PubMed Central

    Suess, Daniel L. M.

    2015-01-01

    Proton reduction and H2 oxidation are key elementary reactions for solar fuel production. Hydrogenases interconvert H+ and H2 with remarkable efficiency and have therefore received much attention in this context. For [FeFe]-hydrogenases, catalysis occurs at a unique cofactor called the H-cluster. In this article, we discuss ways in which EPR spectroscopy has elucidated aspects of the bioassembly of the H-cluster, with a focus on four case studies: EPR spectroscopic identification of a radical en route to the CO and CN− ligands of the H-cluster, tracing 57Fe from the maturase HydG into the H-cluster, characterization of the auxiliary Fe–S cluster in HydG, and isotopic labeling of the CN− ligands of HydA for electronic structure studies of its Hox state. Advances in cell-free maturation protocols have enabled several of these mechanistic studies, and understanding H-cluster maturation may in turn provide insights leading to improvements in hydrogenase production for biotechnological applications. PMID:26508821

  19. Corrosion behaviour of galvanized steel and electroplating steel in aqueous solution: AC impedance study and XPS

    NASA Astrophysics Data System (ADS)

    Lebrini, M.; Fontaine, G.; Gengembre, L.; Traisnel, M.; Lerasle, O.; Genet, N.

    2008-08-01

    The efficiency of a new triazole derivative, namely, 2-{(2-hydroxyethyl)[(4-methyl-1 H-1,2,3-benzotriazol-1-yl)methyl]amino}ethanol (TTA) has been studied for corrosion inhibition of galvanized steel and electroplating steel in aqueous solution. Corrosion inhibition was studied using electrochemical impedance spectroscopy (EIS). These studies have shown that TTA was a very good inhibitor. Data obtained from EIS show a frequency distribution and therefore a modelling element with frequency dispersion behaviour, a constant phase element (CPE) has been used. The corrosion behaviour of galvanized steel and electroplating steel in aqueous solution was also investigated in the presence of 4-methyl-1 H-benzotriazole (TTA unsubstituted) by EIS. These studies have shown that the ability of the molecule to adsorb on the steel surface was dependent on the group in triazole ring substituent. X-ray photoelectron spectroscopy surface analysis with TTA shows that it chemisorbed on surface of galvanized steel and electroplating steel.

  20. Static ankle impedance in stroke and multiple sclerosis: a feasibility study.

    PubMed

    Lee, Hyunglae; Patterson, Tara; Ahn, Jooeun; Klenk, Daniel; Lo, Albert; Krebs, Hermano Igo; Hogan, Neville

    2011-01-01

    Quantitative characterization of ankle mechanical impedance is critical for understanding lower extremity function in persons with neurological disorders. In this paper, we examine the feasibility of employing an ankle robot and multivariable analysis to determine static ankle impedance in 4 patients: 1 with multiple sclerosis and 3 with stroke. We employed a scalar based vector field approximation method which was successful in identifying young healthy subjects' ankle impedance. It enabled clear interpretation of spatial ankle impedance structure and intermuscular feedback at the ankle for both affected and unaffected legs. Measured impedance of two patients was comparable to healthy young subjects, while the other two patients had significantly different static ankle impedance properties. PMID:22256327

  1. Combined Impedance Probe and Langmuir Probe Studies of the Low-Latitude E Region

    NASA Technical Reports Server (NTRS)

    Rowland, D. E.; Pfaff, R. F.; Steigies, C. T.

    2008-01-01

    The EQUIS-2 sounding rocket and radar campaign, launched from Kwajalein Atoll in 2004, included a mission to study low-latitude irregularities and electrodynamics, led by NASA GSFC. This mission included two instrumented rockets launched into the nighttime E region (apogee near 120 km), which included comprehensive electrodynamics and neutral density instrumentation. These rockets carried the first of a new generation of impedance probes, that utilize a wide-band drive signal to simultaneously measure the impedance of an antenna in a plasma as a function of frequency from 7 kEIz to 4 MHz. at a rapid cadence. This technique promises to permit true plasma spectroscopy, and resulted in the identification of multiple plasma resonances and accurate measurements of the plasma density, even in the low density nighttime E region. We present analyses of the technique and resulting spectra, and show how these data may be combined with fixed-bias Langmuir Probe data to infer the temperature structure of the E region as well as providing accurate absolute calibrations for the very high time resolution fixed-bias probe data. The data is shown to agree well with data from ionosonde, the ALTAIR radar, and the Peruvian beacon experiment.

  2. Application of electrochemical impedance spectroscopy: A phase behavior study of babassu biodiesel-based microemulsions.

    PubMed

    Pereira, Thulio C; Conceição, Carlos A F; Khan, Alamgir; Fernandes, Raquel M T; Ferreira, Maira S; Marques, Edmar P; Marques, Aldaléa L B

    2016-11-01

    Microemulsions are thermodynamically stable systems of two immiscible liquids, one aqueous and the other of organic nature, with a surfactant and/or co-surfactant adsorbed in the interface between the two phases. Biodiesel-based microemulsions, consisting of alkyl esters of fatty acids, open a new means of analysis for the application of electroanalytical techniques, and is advantageous as it eliminates the required pre-treatment of a sample. In this work, the phase behaviours of biodiesel-based microemulsions were investigated through the electrochemical impedance spectroscopy (EIS) technique. We observed thatan increase in the amount of biodiesel in the microemulsion formulation increases the resistance to charge transfer at the interface. Also, the electrical conductivity measurements revealed that a decrease or increase in electrical properties depends on the amount of biodiesel. EIS studies of the biodiesel-based microemulsion samples showed the presence of two capacitive arcs: one high-frequency and the other low-frequency. Thus, the formulation of microemulsions plays an important role in estimating the electrical properties through the electrochemical impedance spectroscopy technique. PMID:27276278

  3. Mapping Electrochemical Heterogeneity at Iron Oxide Surfaces: A Local Electrochemical Impedance Study.

    PubMed

    Lucas, Marie; Boily, Jean-François

    2015-12-22

    Alternating current scanning electrochemical microscopy (AC-SECM) was used for the first time to map key electrochemical attributes of oriented hematite (α-Fe2O3) single crystal surfaces at the micron-scale. Localized electrochemical impedance spectra (LEIS) of the (001) and (012) faces provided insight into the spatial variations of local double layer capacitance (C(dl)) and charge transfer resistance (R(ad)). These parameters were extracted by LEIS measurements in the 0.4-8000 Hz range to probe the impedance response generated by the redistribution of water molecules and charge carriers (ions) under an applied AC. These were attributed to local variations in the local conductivity of the sample surfaces. Comparison with global EIS measurements on the same samples uncovered highly comparable frequency-resolved processes, that were broken down into contributions from the bulk hematite, the interface as well as the microelectrode/tip assembly. This work paves the way for new studies aimed at mapping electrochemical processes at the mesoscale on this environmentally and technologically important material. PMID:26625255

  4. A comparative study of feed impedances of a circular and three different spiral antenna arrays

    NASA Astrophysics Data System (ADS)

    Ramachandra, V.; Dey, K. K.; Khastgir, P.

    1982-08-01

    Mathematical derivation of feed impedances of the dipole radiators of a circular and three different spiral arrays has been made for both constant and progressive phase distributions. A set of graphs, which show the variations of these impedances and their components from radiator to radiator, has been obtained. Spiral distributions of impedances can be observed on the Argand diagram in the cases of the three spiral arrays.

  5. Spectroscopic study of sorption of nitrogen heterocyclic compounds on phyllosilicates

    SciTech Connect

    Chattopadhyay, S.; Traina, S.J.

    1999-03-02

    The present study focused on understanding the sorption characteristics of acridine (AcN) and acridine-9-carboxylic acid (AcNCOOH), two typical nitrogen heterocyclic compounds (NHCs), on well-characterized phyllosilicates (hectorite, saponite, and muscovite). Results presented in this article show that the degree of sorption of NHCs on phyllosilicates was dependent on the nature of the participating sorbates and sorbents. Sorption of the selected NHCs was pH-dependent, with maximum sorption occurring at low pH conditions, especially at pH < pK{sub a} of the NHC. Though sorption of the cationic forms of the NHCs on clays was preferred, neutral, zwitterionic, and anionic species of NHCs also sorbed on the clay surfaces. Spectroscopic studies have shown that sorbed NHC molecules formed clusters on clay surfaces, which acted as templates for molecular aggregation. Finally, the authors have also found that the clay surfaces promoted protonation of neutral AcN molecules at low sorbate concentrations.

  6. Particle in a Disk: A Spectroscopic and Computational Laboratory Exercise Studying the Polycyclic Aromatic Hydrocarbon Corannulene

    ERIC Educational Resources Information Center

    Frey, E. Ramsey; Sygula, Andrzej; Hammer, Nathan I.

    2014-01-01

    This laboratory exercise introduces undergraduate chemistry majors to the spectroscopic and theoretical study of the polycyclic aromatic hydrocarbon (PAH), corannulene. Students explore the spectroscopic properties of corannulene using UV-vis and Raman vibrational spectroscopies. They compare their experimental results to simulated vibrational…

  7. Infrared Imaging, Spectroscopic, and Photometric Studies of Comets

    NASA Technical Reports Server (NTRS)

    Gehrz, Robert D.

    1997-01-01

    We have continued our program of infrared (IR) photometric, imaging, spectroscopic, and polarimetric temporal observations of comets to study the properties of comet dust and comet nuclei. During the first two years we digitized our IR data base on P/Halley and other recent comets to facilitate further analysis and comparison with other data bases, and found compelling evidence for the emission of a burst of small grains from P/Halley's nucleus at perihelion. We reported imaging and photometric observations of Comets Austin 1990 V and Swift-Tuttle 1992. The Swift-Tuttle 1992t observations included IR photometry, several 7-14 micron long-slit spectra of the coma and a time-sequence of more than 150 10 micron broadband images of the coma. An analysis of near-IR images of the inner coma of P/Halley obtained on three consecutive nights in 1986 March showed sunwardjets. We completed our analysis of IR imaging spectrosco-photometric data on comets. We also obtained observations of Comets Hyakutake 1996 B2 and Hale/Bopp 1995 01. We obtained infrared imaging, photometric, spectroscopic and polarimetric temporal observations of bright comets using a network of five telescopes, with emphasis on simultaneous observations of comets at many wavelengths with different instruments. Our program offers several unique advantages: 1) rapid observational response to new comets with dedicated infrared telescopes; 2) observations within a few degrees of the sun when comets are near perihelion and 3) access to advanced infrared array imagers and spectrometers. In particular, reduction, analysis, publication and archiving of our Jupiter/sl-9 and Comet Hyakutake infrared data received special emphasis. Instrumentation development included installation of the latest version of the innovative FORTH telescope control and a data acquisition system that enables us to control three telescopes remotely by telephone from anywhere in the world for comet observations in broad daylight. We have

  8. Spectroscopic Studies of Molecular Systems relevant in Astrobiology

    NASA Astrophysics Data System (ADS)

    Fornaro, Teresa

    2016-01-01

    In the Astrobiology context, the study of the physico-chemical interactions involving "building blocks of life" in plausible prebiotic and space-like conditions is fundamental to shed light on the processes that led to emergence of life on Earth as well as to molecular chemical evolution in space. In this PhD Thesis, such issues have been addressed both experimentally and computationally by employing vibrational spectroscopy, which has shown to be an effective tool to investigate the variety of intermolecular interactions that play a key role in self-assembling mechanisms of nucleic acid components and their binding to mineral surfaces. In particular, in order to dissect the contributions of the different interactions to the overall spectroscopic signals and shed light on the intricate experimental data, feasible computational protocols have been developed for the characterization of the spectroscopic properties of such complex systems. This study has been carried out through a multi-step strategy, starting the investigation from the spectroscopic properties of the isolated nucleobases, then studying the perturbation induced by the interaction with another molecule (molecular dimers), towards condensed phases like the molecular solid, up to the case of nucleic acid components adsorbed on minerals. A proper modeling of these weakly bound molecular systems has required, firstly, a validation of dispersion-corrected Density Functional Theory methods for simulating anharmonic vibrational properties. The isolated nucleobases and some of their dimers have been used as benchmark set for identifying a general, reliable and effective computational procedure based on fully anharmonic quantum mechanical computations of the vibrational wavenumbers and infrared intensities within the generalized second order vibrational perturbation theory (GVPT2) approach, combined with the cost-effective dispersion-corrected density functional B3LYP-D3, in conjunction with basis sets of

  9. Nonplanar property study of antifungal agent tolnaftate-spectroscopic approach

    NASA Astrophysics Data System (ADS)

    Arul Dhas, D.; Hubert Joe, I.; Roy, S. D. D.; Balachandran, S.

    2011-09-01

    Vibrational analysis of the thionocarbamate fungicide tolnaftate which is antidermatophytic, antitrichophytic and antimycotic agent, primarily inhibits the ergosterol biosynthesis in the fungus, was carried out using NIR FT-Raman and FTIR spectroscopic techniques. The equilibrium geometry, various bonding features, harmonic vibrational wavenumbers and torsional potential energy surface (PES) scan studies have been computed using density functional theory method. The detailed interpretation of the vibrational spectra has been carried out with the aid of VEDA.4 program. Vibrational spectra, natural bonding orbital (NBO) analysis and optimized molecular structure show the clear evidence for electronic interaction of thionocarbamate group with aromatic ring. Predicted electronic absorption spectrum from TD-DFT calculation has been compared with the UV-vis spectrum. The Mulliken population analysis on atomic charges and the HOMO-LUMO energy were also calculated. Vibrational analysis reveals that the simultaneous IR and Raman activation of the C-C stretching mode in the phenyl and naphthalene ring provide evidence for the charge transfer interaction between the donor and acceptor groups and is responsible for its bioactivity as a fungicide.

  10. In vitro spectroscopic study of piperine-encapsulated nanosize liposomes.

    PubMed

    Pentak, Danuta

    2016-03-01

    Black pepper is a source of effective antioxidants. It contains several powerful antioxidants and is thus one of the most important spices for preventing and curtailing oxidative stress. There is considerable interest in the development of a drug-delivery systems that would result in the selective delivery of antioxidants to tissues in sufficient concentrations to ameliorate oxidant-induced tissue injuries. Liposomes are biocompatible, biodegradable and nontoxic artificial phospholipid vesicles that offer the possibility of carrying hydrophilic, hydrophobic and amphiphilic molecules. This article focuses on the use of liposomes for the delivery of antioxidants in the prevention or treatment of pathological conditions related to oxidative stress. Liposome formulations of piperine were analyzed with various spectroscopic methods. The formulation with the highest entrapment efficiency (90.5%) was formulated with an L-α-phosphatidylcholine dipalmitoyl (DPPC):piperine, 30:1 molar ratio, and total lipid count of 19.47 mg/ml in the final liposomal preparation. The liposome formulation was found to be stable after storage at 4 °C, protected from light, for a minimum of 3 weeks. The incremental process of piperine penetration through the phospholipid membrane was analyzed using the FT-IR, UV-Vis and NMR methods. Temperature stability studies carried out at 37 °C showed the highest percentage of piperine release in the first 3 h of incubation. PMID:26493066

  11. Vibrational spectroscopic study of vinyl substituted polycyclic aromatic hydrocarbons.

    PubMed

    Maurya, Anju; Rastogi, Shantanu

    2015-12-01

    The mid infrared emission features observed in various astrophysical sources are attributed to polycyclic aromatic hydrocarbon (PAH) molecules. The models of emission spectra from a collection of PAHs show uncertainty in matching the 6.2 μm feature. This indicates the need to consider a larger variety of PAHs and PAH derivatives. Chemical pathways towards formation of PAHs in the astrophysical environments involve vinyl substituted PAHs as intermediate products. Vibrational spectroscopic study of vinyl-PAHs is reported in the present work. The vinyl group is substituted at similar positions in eight different PAHs. The obtained optimized structures show that vinyl substitution at 2 position in acenes gives planar geometry, while all other vinyl-PAHs are non-planar. Infrared spectra is simulated for neutrals as well as for cations. The results are compared with the spectra of corresponding plain PAHs and analyzed for possible match with astrophysical observations. New features, due to vinyl group in the composite spectra, identified at 6.64, 6.92, 7.27, 8.77 and 10.35 μm fall close to some sub features of the observed emission spectra. The paper provides data that may be used in the emission models particularly along proto planetary nebulae type cool objects. PMID:26117194

  12. Spectroscopic studies of anthracyclines: Structural characterization and in vitro tracking.

    PubMed

    Szafraniec, Ewelina; Majzner, Katarzyna; Farhane, Zeineb; Byrne, Hugh J; Lukawska, Malgorzata; Oszczapowicz, Irena; Chlopicki, Stefan; Baranska, Malgorzata

    2016-12-01

    A broad spectroscopic characterization, using ultraviolet-visible (UV-vis) and Fourier transform infrared absorption as well as Raman scattering, of two commonly used anthracyclines antibiotics (DOX) daunorubicin (DNR), their epimers (EDOX, EDNR) and ten selected analogs is presented. The paper serves as a comprehensive spectral library of UV-vis, IR and Raman spectra of anthracyclines in the solid state and in solution. The particular advantage of Raman spectroscopy for the measurement and analysis of individual antibiotics is demonstrated. Raman spectroscopy can be used to monitor the in vitro uptake and distribution of the drug in cells, using both 488nm and 785nm as source wavelengths, with submicrometer spatial resolution, although the cellular accumulation of the drug is different in each case. The high information content of Raman spectra allows studies of the drug-cell interactions, and so the method seems very suitable for monitoring drug uptake and mechanisms of interaction with cellular compartments at the subcellular level. PMID:27372511

  13. Fluorination of graphene: a spectroscopic and microscopic study.

    PubMed

    Wang, Bei; Wang, Junjie; Zhu, Jun

    2014-02-25

    Since the advent of graphene, there has been intense interest in exploring the possibility of incorporating fluorinated graphene (FG), an ultrathin insulator, into graphene electronics as barriers, gate dielectrics, and optoelectronic elements. Here we report on the synthesis of FG from single-layer graphene sheets grown by chemical vapor deposition (CVD) using CF4 plasma. We examine its properties systematically via microscopic and spectroscopic probes. Our studies show that, by controlling the conditions of the plasma, FG of varying fluorine coverage can be produced; however, the resulting material contains a mixture of CFx (x = 1-3) bonds. Existing grain boundaries and lattice defects of CVD graphene play an important role in controlling its rate of fluorination and the damage of the sheet. Combining topography and current mapping, we demonstrate that the spatial distribution of fluorine on CVD graphene is highly inhomogeneous, where multilayer islands and structural features such as folds, wrinkles, and ripples are less fluorinated and consequently form a conductive network through which charge transport occurs. It is the properties of this network that manifest in the electrical transport of FG sheets. Our experiments reveal the many challenges of deriving electronics-quality FG from current CVD graphene while at the same time point to the possible solutions and potential of FG in graphene electronics and optoelectronics. PMID:24471932

  14. A spectroscopic study of the globular Cluster NGC 4147

    NASA Astrophysics Data System (ADS)

    Villanova, S.; Monaco, L.; Moni Bidin, C.; Assmann, P.

    2016-08-01

    We present the abundance analysis for a sample of 18 red giant branch stars in the metal-poor globular cluster NGC 4147 based on medium- and high-resolution spectra. This is the first extensive spectroscopic study of this cluster. We derive abundances of C, N, O, Na, Mg, Al, Si, Ca, Ti, Cr, Fe, Ni, Y, Ba, and Eu. We find a metallicity of [Fe/H] = -1.84 ± 0.02 and an α-enhancement of +0.38 ± 0.05 (errors on the mean), typical of halo globular clusters in this metallicity regime. A significant spread is observed in the abundances of light elements C, N, O, Na, and Al. In particular, we found an Na-O anticorrelation and Na-Al correlation. The cluster contains only ˜15 per cent of stars that belong to the first generation (Na-poor and O-rich). This implies that it suffered a severe mass-loss during its lifetime. Its [Ca/Fe] and [Ti/Fe] mean values agree better with the Galactic halo trend than with the trend of extragalactic environments at the cluster metallicity. This possibly suggests that NGC 4147 is a genuine Galactic object at odd with what claimed by some author that proposed the cluster to be member of the Sagittarius dwarf galaxy. An antirelation between the light s-process element Y and Na may also be present.

  15. Spectroscopic study of HNO3 dissociation on ice.

    PubMed

    Marchand, Patrick; Marcotte, Guillaume; Ayotte, Patrick

    2012-12-13

    A detailed spectroscopic study of HNO(3):H(2)O binary amorphous mixtures, and of the adsorption of HNO(3) onto ice, is reported. Using a classical optics model, the extent of intermixing and of ionic dissociation of adsorbed HNO(3), which forms a strong acid with liquid water, is determined as a function of HNO(3) coverage and temperature. Even at temperatures as low as 45 K, where intermixing is limited to at most a few molecular layers at the interface, ionic dissociation of adsorbed HNO(3) is observed to be extensive. While some amount of molecularly adsorbed HNO(3) is observed at the surface of ice at 45 K, its ionic dissociation occurs irreversibly upon heating the ice substrate to 120 K. The molecularly adsorbed state of HNO(3) is not restored upon cooling, suggesting HNO(3) is a metastable entity at the surface of ice. Therefore, despite ionic dissociation of HNO(3) being thermodynamically favored, it appears to be kinetically inhibited at the surface of amorphous solid water at temperatures below 120 K. PMID:23130955

  16. New homotrinuclear lanthanide complexes: synthesis, characterization and spectroscopic study.

    PubMed

    Silva, Wagner E; Belian, Mônica Freire; Freire, Ricardo O; de Sá, Gilberto F; Alves, Severino

    2010-09-23

    This work presents the synthesis and spectroscopic study of new homotrinuclear (TRI) systems for photonics applications. The luminescence spectroscopy shows characteristics transitions of Eu(III) and Tb(III) ions. For the Gd(III) complexes, the triplets states were determined by phosphorescence measurement. The complexes’ coordination geometries were calculated using the Sparkle/AM1 model. For the europium systems, the Sparkle/AM1 geometries were used to calculate all details involved in the energy transfer process, and the theoretical quantum yields were determined. From an energy diagram, that estimates triplet levels, it was possible to understand some experimental phenomenon, such as weak luminescence for precursor complex (without heterocyclics ligands), and ligands emission in terbium complexes. Some of these observations can also be explained by the Jablonski diagrams that describe, based on theoretical calculations, all luminescent process. The synthesized complexes showed high values of quantum yield in ethanolic environment: 50% for EuTRIDipy, 26% EuTRITerpy, and 56% for EuTRIPhen complexes. PMID:20738128

  17. Raman spectroscopic studies of the cure of dicyclopentadiene (DCPD)

    NASA Astrophysics Data System (ADS)

    Barnes, S. E.; Brown, E. C.; Corrigan, N.; Coates, P. D.; Harkin-Jones, E.; Edwards, H. G. M.

    2005-10-01

    The cure of polydicyclopentadiene conducted by ring-opening metathesis polymerisation in the presence of a Grubbs catalyst was studied using non-invasive Raman spectroscopy. The spectra of the monomer precursor and polymerised product were fully characterised and all stages of polymerisation monitored. Because of the monomer's high reactivity, the cure process is adaptable to reaction injection moulding and reactive rotational moulding. The viscosity of the dicyclopentadiene undergoes a rapid change at the beginning of the polymerisation process and it is critical that the induction time of the viscosity increase is determined and controlled for successful manufacturing. The results from this work show non-invasive Raman spectroscopic monitoring to be an effective method for monitoring the degree of cure, paving the way for possible implementation of the technique as a method of real-time analysis for control and optimisation during reactive processing. Agreement is shown between Raman measurements and ultrasonic time of flight data acquired during the initial induction period of the curing process.

  18. A new application of electrical impedance spectroscopy for measuring glucose metabolism: a phantom study

    NASA Astrophysics Data System (ADS)

    Dhurjaty, Sreeram; Qiu, Yuchen; Tan, Maxine; Liu, Hong; Zheng, Bin

    2015-03-01

    Glucose metabolism relates to biochemical processes in living organisms and plays an important role in diabetes and cancer-metastasis. Although many methods are available for measuring glucose metabolism-activities, from simple blood tests to positron emission tomography, currently there is no robust and affordable device that enables monitoring of glucose levels in real-time. In this study we tested feasibility of applying a unique resonance-frequency based electronic impedance spectroscopy (REIS) device that has been, recently developed to measure and monitor glucose metabolism levels using a phantom study. In this new testing model, a multi-frequency electrical signal sequence is applied and scanned through the subject. When the positive reactance of an inductor inside the device cancels out the negative reactance of the capacitance of the subject, the electrical impedance reaches a minimum value and this frequency is defined as the resonance frequency. The REIS system has a 24-bit analog-to-digital signal convertor and a frequency-resolution of 100Hz. In the experiment, two probes are placed inside a 100cc container initially filled with distilled water. As we gradually added liquid-glucose in increments of 1cc (250mg), we measured resonance frequencies and minimum electrical signal values (where A/D was normalized to a full scale of 1V). The results showed that resonance frequencies monotonously decreased from 243kHz to 178kHz, while the minimum voltages increased from 405mV to 793mV as the added amount of glucose increased from 0 to 5cc. The study demonstrated the feasibility of applying this new REIS technology to measure and/or monitor glucose levels in real-time in future.

  19. Raman spectroscopic studies of amorphous carbon and buckminsterfullerene

    SciTech Connect

    Sinha, K.

    1992-01-01

    Raman spectroscopic techniques have been applied to investigate a variety of carbon systems. Using resonance Raman spectroscopy as a probe for optical transitions in a system, a careful quantitative estimate of the Raman cross-section of graphite in the pre-resonance regime has been made. Raman and resonance Raman spectroscopy have been used to correlate the structural and electronic properties of amorphous carbon materials. The low optical gaps and e-2e spectroscopy measurements on evaporated carbon films suggests a structure close to graphite. Raman measurements, however, reveal a great amount of disorder in the material. This apparent contradiction has been resolved through the use of a phenomenological model for the electronic density of states for amorphous carbon systems. Raman spectroscopy has also been used to study the vibrational and the electronic properties of the recently discovered third allotrope of carbon, C[sub 60]. The vibrational modes of this molecule have been studied in great detail. The observed vibrational spectra confirms earlier work in this material. Furthermore, the mode frequencies have been found to be in reasonably good agreement with theoretical predictions. Resonance Raman studies of solid C[sub 60] and C[sub 60] dissolved in solvents has revealed, in the solid phase, the existence of optical transitions well below the symmetry allowed transitions for the isolated molecules. Loss of inversion symmetry in the solid state has been proposed to account for the resonance observed in the Raman excitation profile. Original Raman measurements on C[sub 60] revealed a strong peak at 1469 cm[sup [minus]1]. The peak was found to obey the correct selection rule for symmetric A[sub g] mode and was assigned to the [open quotes]pentagonal pinch[close quotes] mode of the molecule.

  20. Photoacoustic FTIR spectroscopic study of undisturbed human cortical bone

    NASA Astrophysics Data System (ADS)

    Gu, Chunju; Katti, Dinesh R.; Katti, Kalpana S.

    2013-02-01

    Chemical pretreatment has been the prevailing sample preparation procedure for infrared (IR) spectroscopic studies on bone. However, experiments have indicated that chemical pretreatment can potentially affect the interactions between the components. Typically the IR techniques have involved transmission experiments. Here we report experimental studies using photoacoustic Fourier transform infrared spectroscopy (PA-FTIR). As a nondestructive technique, PA-FTIR can detect absorbance spectrum from a sample at controllable sampling depth and with little or no sample preparation. Additionally, the coupling inert gas, helium, which is utilized in the PA-FTIR system, can inhibit bacteria growth of bone by displacing oxygen. Therefore, we used this technique to study the undisturbed human cortical bone. It is found that photoacoustic mode (linear-scan, LS-PA-FTIR) can obtain basically similar spectra of bone as compared to the traditional transmission mode, but it seems more sensitive to amide III and ν2 carbonate bands. The ν3 phosphate band is indicative of detailed mineral structure and symmetry of native bone. The PA-FTIR depth profiling experiments on human cortical bone also indicate the influence of water on OH band and the cutting effects on amide I and mineral bands. Our results indicate that phosphate ion geometry appears less symmetric in its undisturbed state as detected by the PA-FTIR as compared to higher symmetry observed using transmission techniques on disturbed samples. Moreover, the PA-FTIR spectra indicate a band at 1747 cm-1 possibly resulting from Cdbnd O stretching of lipids, cholesterol esters, and triglycerides from the arteries. Comparison of the spectra in transverse and longitudinal cross-sections demonstrates that, the surface area of the longitudinal section bone appears to have more organic matrix exposed and with higher mineral stoichiometry.

  1. The Pt(111)/electrolyte interface under oxygen reduction reaction conditions: an electrochemical impedance spectroscopy study.

    PubMed

    Bondarenko, Alexander S; Stephens, Ifan E L; Hansen, Heine A; Pérez-Alonso, Francisco J; Tripkovic, Vladimir; Johansson, Tobias P; Rossmeisl, Jan; Nørskov, Jens K; Chorkendorff, Ib

    2011-03-01

    The Pt(111)/electrolyte interface has been characterized during the oxygen reduction reaction (ORR) in 0.1 M HClO(4) using electrochemical impedance spectroscopy. The surface was studied within the potential region where adsorption of OH* and O* species occur without significant place exchange between the adsorbate and Pt surface atoms (0.45-1.15 V vs RHE). An equivalent electric circuit is proposed to model the Pt(111)/electrolyte interface under ORR conditions within the selected potential window. This equivalent circuit reflects three processes with different time constants, which occur simultaneously during the ORR at Pt(111). Density functional theory (DFT) calculations were used to correlate and interpret the results of the measurements. The calculations indicate that the coadsorption of ClO(4)* and Cl* with OH* is unlikely. Our analysis suggests that the two-dimensional (2D) structures formed in O(2)-free solution are also formed under ORR conditions. PMID:21244087

  2. Impedance studies of a green blend polymer electrolyte based on PVA and Aloe-vera

    NASA Astrophysics Data System (ADS)

    Selvalakshmi, S.; Mathavan, T.; Vijaya, N.; Selvasekarapandian, Premalatha, M.; Monisha, S.

    2016-05-01

    The development of polymer electrolyte materials for energy generating and energy storage devices is a challenge today. A new type of blended green electrolyte based on Poly-vinyl alcohol (PVA) and Aloe-vera has been prepared by solution casting technique. The blending of polymers may lead to the increase in stability due to one polymer portraying itself as a mechanical stiffener and the other as a gelled matrix supported by the other. The prepared blend electrolytes were subjected to Ac impedance studies. It has been found out that the polymer film in which 1 gm of PVA was dissolved in 40 ml of Aloe-vera extract exhibits highest conductivity and its value is 3.08 × 10-4 S cm-1.

  3. Degradation of Bilayer Organic Light-Emitting Diodes Studied by Impedance Spectroscopy.

    PubMed

    Sato, Shuri; Takata, Masashi; Takada, Makoto; Naito, Hiroyoshi

    2016-04-01

    The degradation of bilayer organic light-emitting diodes (OLEDs) with a device structure of N,N'-di(1-naphthyl)-N,N'-diphenylbenzidine (α-NPD) (hole transport layer) and tris-(8-hydroxyquinolate)aluminum (Alq3) (emissive layer and electron transport layer) has been studied by impedance spectroscopy and device simulation. Two modulus peaks are found in the modulus spectra of the OLEDs below the electroluminescence threshold. After aging of the OLEDs, the intensity of electroluminescence is degraded and the modulus peak due to the Alq3 layer is shifted to lower frequency, indicating that the resistance of the Alq3 layer is increased. Device simulation reveals that the increase in the resistance of the Alq3 layer is due to the decrease in the electron mobility in the Alq3 layer. PMID:27451634

  4. Numerical Study of Three Dimensional Effects in Longitudinal Space-Charge Impedance

    SciTech Connect

    Halavanau, A.; Piot, P.

    2015-06-01

    Longitudinal space-charge (LSC) effects are generally considered as detrimental in free-electron lasers as they can seed instabilities. Such “microbunching instabilities” were recently shown to be potentially useful to support the generation of broadband coherent radiation pulses [1, 2]. Therefore there has been an increasing interest in devising accelerator beamlines capable of sustaining this LSC instability as a mechanism to produce a coherent light source. To date most of these studies have been carried out with a one-dimensional impedance model for the LSC. In this paper we use a N-body “Barnes-Hut” algorithm [3] to simulate the 3D space charge force in the beam combined with elegant [4] and explore the limitation of the 1D model often used

  5. Effect of temperature on the methotrexate BSA interaction: Spectroscopic study

    NASA Astrophysics Data System (ADS)

    Sułkowska, A.; Maciążek, M.; Równicka, J.; Bojko, B.; Pentak, D.; Sułkowski, W. W.

    2007-05-01

    Rheumatoid arthritis (RA) is an autoimmune and chronic inflammatory illness which affects about one percent of the world's population. Methotrexate (4-amino-10-methylfolic acid) (MTX) also known as amethopterin is commonly used to treat rheumatoid arthritis (RA). It is transported in the circulary system as a complex with serum albumin. The aim of this study was to investigate the interactions of MTX with transporting protein with the use of spectroscopic methods. The binding of MTX to bovine serum albumin (BSA) was studied by monitoring the changes in the emission fluorescence spectra of protein in the presence of MTX at excitation wavelength of 280 nm and 295 nm. The quenching of protein fluorescence at temperature range from 298 K to 316 K was observed. Energy transfer between methotrexate and fluorophores contained in the serum albumin structure was found at the molar ratio MTX:BSA 7.5:1. The relative fluorescence intensity of BSA decreases with increase of temperature. Similar results were observed for BSA excited with 280 nm and 295 nm at the same temperature range. The presence of MTX seems to prevent these changes. Temperature dependence of the binding constant has been presented. The binding and quenching constants for equilibrium complex were calculated using Scatchard and Stern-Volmer method, respectively. The results show that MTX forms π-π complex with aromatic amino acid residues of BSA. The binding site for MTX on BSA was found to be situated in the hydrophobic IIA or IB subdomain where the Trps were located. The spontaneity of MTX-BSA complex formation in the temperature range 298-316 K was ascertained.

  6. The spectroscopic study of building composites containing natural sorbents

    NASA Astrophysics Data System (ADS)

    Król, M.; Mozgawa, W.

    2011-08-01

    This work presents the results of FT-IR spectroscopic studies of heavy metal cations (Ag +, Pb 2+, Zn 2+, Cd 2+ and Cr 3+) immobilization from aqueous solutions on natural sorbents. The sorption has been conducted on sodium forms of zeolite (clinoptilolite) and clay minerals (mixtures containing mainly montmorillonite and kaolinite) which have been separated from natural Polish deposit. In the next part of the work both sorbents were used to obtain new building composites. It was proven those heavy metal cations' sorption causes changes in IR spectra of the zeolite and clay minerals. These alterations are dependent on the way the cations were sorbed. In the case of zeolite, variations of the bands corresponding to the characteristic ring vibrations have been observed. These rings occur in pseudomolecular complexes 4-4-1 (built of alumino- and silicooxygen tetrahedra) which constitute the secondary building units (SBU) and form spatial framework of the zeolite. The most significant changes have been determined in the region of pseudolattice vibrations (650-700 cm -1). In the instance of clay minerals, changes in the spectra occur at two ranges: 1200-800 cm -1 - the range of the bands assigned to asymmetric Si-O(Si,Al) and bending Al-OH vibrations and 3800-3000 cm -1 - the range of the bands originating from OH - groups stretching vibrations. Next results indicate possibilities of applying the used natural sorbents for the obtainment of new building materials having favourable composition and valuable properties. The zeolite was used for obtaining autoclaved materials with an addition of CaO, and the clay minerals for ceramic sintered materials with an addition of quartz and clinoptilolite were produced. FT-IR studies were also conducted on the obtained materials.

  7. LEAD SORPTION ON RUTHENIUM OXIDE: A MACROSCOPIC AND SPECTROSCOPIC STUDY

    EPA Science Inventory

    The sorption and desorption of Pb on RuO2 xH2O were examined kinetically and thermodynamically via spectroscopic and macroscopic investigations. X-ray absorption spectroscopy (XAS) was employed to determine the sorption mechanism with regard to identity of nearest atomic neighbo...

  8. Spectroscopic Studies of Molecular Systems relevant in Astrobiology

    NASA Astrophysics Data System (ADS)

    Fornaro, Teresa

    2016-01-01

    In the Astrobiology context, the study of the physico-chemical interactions involving "building blocks of life" in plausible prebiotic and space-like conditions is fundamental to shed light on the processes that led to emergence of life on Earth as well as to molecular chemical evolution in space. In this PhD Thesis, such issues have been addressed both experimentally and computationally by employing vibrational spectroscopy, which has shown to be an effective tool to investigate the variety of intermolecular interactions that play a key role in self-assembling mechanisms of nucleic acid components and their binding to mineral surfaces. In particular, in order to dissect the contributions of the different interactions to the overall spectroscopic signals and shed light on the intricate experimental data, feasible computational protocols have been developed for the characterization of the spectroscopic properties of such complex systems. This study has been carried out through a multi-step strategy, starting the investigation from the spectroscopic properties of the isolated nucleobases, then studying the perturbation induced by the interaction with another molecule (molecular dimers), towards condensed phases like the molecular solid, up to the case of nucleic acid components adsorbed on minerals. A proper modeling of these weakly bound molecular systems has required, firstly, a validation of dispersion-corrected Density Functional Theory methods for simulating anharmonic vibrational properties. The isolated nucleobases and some of their dimers have been used as benchmark set for identifying a general, reliable and effective computational procedure based on fully anharmonic quantum mechanical computations of the vibrational wavenumbers and infrared intensities within the generalized second order vibrational perturbation theory (GVPT2) approach, combined with the cost-effective dispersion-corrected density functional B3LYP-D3, in conjunction with basis sets of

  9. Impedance calculation for ferrite inserts

    SciTech Connect

    Breitzmann, S.C.; Lee, S.Y.; Ng, K.Y.; /Fermilab

    2005-01-01

    Passive ferrite inserts were used to compensate the space charge impedance in high intensity space charge dominated accelerators. They study the narrowband longitudinal impedance of these ferrite inserts. they find that the shunt impedance and the quality factor for ferrite inserts are inversely proportional to the imaginary part of the permeability of ferrite materials. They also provide a recipe for attaining a truly passive space charge impedance compensation and avoiding narrowband microwave instabilities.

  10. Prospective study comparing skin impedance with EEG parameters during the induction of anaesthesia with fentanyl and etomidate

    PubMed Central

    2010-01-01

    Objective Sympathetic stimulation leads to a change in electrical skin impedance. So far it is unclear whether this effect can be used to measure the effects of anaesthetics during general anaesthesia. The aim of this prospective study is to determine the electrical skin impedance during induction of anaesthesia for coronary artery bypass surgery with fentanyl and etomidate. Methods The electrical skin impedance was measured with the help of an electro-sympathicograph (ESG). In 47 patients scheduled for elective cardiac surgery, anaesthesia was induced with intravenous fentanyl 10 μg/kg and etomidate 0.3 mg/kg. During induction, the ESG (Electrosympathicograph), BIS (Bispectral IndeX), BP (arterial blood pressure) and HR (heart rate) values of each patient were recorded every 20 seconds. The observation period from administration of fentanyl to intubation for surgery lasted 4 min. Results The ESG recorded significant changes in the electrical skin impedance after administration of fentanyl and etomidate(p < 0.05). During induction of anaesthesia, significant changes of BIS, HR and blood pressure were observed as well (p < 0.05). Conclusions The electrical skin impedance measurement may be used to monitor the effects of anesthetics during general anaesthesia. PMID:20452883

  11. Spectroscopic studies of uranium species for environmental decontamination applications

    NASA Astrophysics Data System (ADS)

    Eng, Charlotte

    After the Cold War, Department of Energy began to concentrate its efforts on cleanup of former nuclear material processing facilities, especially uranium-contaminated groundwater and soil. This research aims to study uranium association to both organic and inorganic compounds found in the contaminated environment in the hopes that the information gathered can be applied to the development and optimization of cost-effective remediation techniques. Spectroscopic and electrochemical methods will be employed to examine the behavior of uranium in given conditions to further our understanding of its impact on the environment. Uranium found in groundwater and soil bind with various ligands, especially organic ligands present in the environment due to natural sources (e.g. metabolic by-products or degradation of plants and animals) or man-made sources (e.g. chelating agents used in operating or cleanup of uranium processing facilities). We selected reasonable analogs of naturally occurring matter and studied their structure, chemical and electrochemical behavior and found that the structure of uranyl complexes depends heavily on the nature of the ligand and environmental factors such as pH. Association of uranium-organic complexes with anaerobic bacteria, Clostridium sp. was studied to establish if the bacteria can effectively bioreduce uranium while going through normal bacterial activity. It was found that the nature of the organic ligand affected the bioavailability and toxicity of the uranium on the bacteria. In addition, we have found that the type of iron corrosion products and uranyl species present on the surface of corroded steel depended on various environmental factors, which subsequently affected the removal rate of uranium by a citric acid/hydrogen peroxide/deionized water cleaning process. The method was found to remove uranium from only the topmost corrosion layers and residual uranium could be found (a) deeper in the corrosion layers where it is occluded by

  12. Computational Study on the Steady-state Impedance of Saturated-core Superconducting Fault Current Limiter

    NASA Astrophysics Data System (ADS)

    Zhang, C.; Tang, Y.; Liang, S.; Ren, L.; Wang, Z.; Xu, Y.

    This paper presents the electromagnetic analysis of a high voltage saturated-core superconducting fault current limiter (SCSFCL). The numerical analyses of a three-dimensional (3D) model is shown, and the specific parameters are given. The model focus on the steady-state impedance of the limiter when connected to the power grid. It analyzed the dependence of steady-state impedance on the AC coil current, and the relationship between oil gap and coil inductance. The results suggest that, adding oil gap between slice of silicon steel can reduce the core cross-section, restrain the ultraharmonic and decrease the steady-state impedance. As the core cross-section of AC limb decreased from 4344 cm2 to 3983 cm2, the total harmonic distortion for voltage decreased from 2.4% to 1.8%, and the impedance decreased from 1.082 Ω to 1.069 Ω(Idc=400A,Iac=1296A).

  13. Spectroscopic Studies of the Several Isomers of UO3

    SciTech Connect

    Sweet, Lucas E.; Reilly, Dallas D.; Abrecht, David G.; Buck, Edgar C.; Meier, David E.; Su, Yin-Fong; Brauer, Carolyn S.; Schwantes, Jon M.; Tonkyn, Russell G.; Szecsody, James E.; Blake, Thomas A.; Johnson, Timothy J.

    2013-09-26

    Uranium trioxide is known to adopt seven different structural forms. While these structural forms have been well characterized using x-ray or neutron diffraction techniques, little work has been done to characterize their spectroscopic properties, particularly of the pure phases. Since the structural isomers of UO3 all have similar thermodynamic stabilities and most tend to hydrolyze under open atmospheric conditions, mixtures of UO3 phases and the hydrolysis products are common. Much effort went into isolating pure phases of UO3. Utilizing x-ray diffraction as a sample identification check, UV/Vis/NIR spectroscopic signatures of α-UO3, β-UO3, γ-UO3 and UO2(OH)2 products were obtained. The spectra of the pure phases can now be used to characterize typical samples of UO3, which are often mixtures of isomers.

  14. Electron Spin Resonance Spectroscopic Studies of Radical Cation Reactions.

    NASA Astrophysics Data System (ADS)

    Dai, Sheng

    1990-01-01

    A spin Hamiltonian suitable for theoretical analyses of ESR spectra in this work is derived by using the general effective Hamiltonian theory in the usual Schrodinger representation. The Permutation Indices method is extended to obtain the dynamic exchange equations used in ESR lineshape simulation. The correlation between beta-hydrogen coupling constants and their geometric orientations is derived through the use of a perturbation method. The three electron bond model is extended to rationalize unimolecular rearrangements of radical cations. The ring-closed radical cations of 9,10-octalin oxide and syn-sesquinorbornene oxide have been characterized by ESR spectroscopy in the CFCl_3 matrix at low temperature. The ESR spectra of the former radical cation exhibit a novel alternating linewidth effect arising from an internal relation between the coupling constants for the four equivalent pairs of hydrogens. The self-electron-transfer rate constants between the methyl viologen dication and cation have been determined by dynamic ESR lineshape simulations at room temperature in allyl alcohol, water, methanol and propargyl alcohol solvents. The radical cation formed by the radiolytic oxidation of allylamine in Freon matrices at 77 K is shown to be the 3-iminiopropyl distonic species(3-iminium-1-propyl radical) resulting from a symmetry-allowed 1,2-hydrogen shift in the parent radical cation. The nucleophilic endocyclization of the but-3-en-1-ol radical cation to the protonated tetrahydrofuran -3-yl radical was observed in the radiolytic oxidation of but-3-en-1-ol in Freon matrices. ESR studies of the radiolytic oxidation of 1,5-hexadiyne have resulted in the first spectroscopic characterization of the radical cation Cope rearrangement, the 1,5-hexadiyne radical cation isomerizing to the 1,2,4,5 -hexatetraene radical cation. ESR studies show that the symmetric(C_{rm 2v}) bicyclo (3.3.0) -octa-2,6-diene-4,8-diyl(a bridged 1,4 -bishomobenzene species) radical cation is

  15. Study of High-Frequency Impedance of Small-Angle Tapers and Collimators

    SciTech Connect

    Stupakov, Gennady; Podobedov, B.; /Brookhaven

    2010-06-04

    Collimators and transitions in accelerator vacuum chambers often include small-angle tapering to lower the wakefields generated by the beam. While the low-frequency impedance is well described by Yokoya's formula (for axisymmetric geometry), much less is known about the behavior of the impedance in the high frequency limit. In this paper we develop an analytical approach to the highfrequency regime for round collimators and tapers. Our analytical results are compared with computer simulations using the code ECHO.

  16. A PARAMETRIC STUDY OF BCS RF SURFACE IMPEDANCE WITH MAGNETIC FIELD USING THE XIAO CODE

    SciTech Connect

    Reece, Charles E.; Xiao, Binping

    2013-09-01

    A recent new analysis of field-dependent BCS rf surface impedance based on moving Cooper pairs has been presented.[1] Using this analysis coded in Mathematica TM, survey calculations have been completed which examine the sensitivities of this surface impedance to variation of the BCS material parameters and temperature. The results present a refined description of the "best theoretical" performance available to potential applications with corresponding materials.

  17. Photometric and spectroscopic study of cD galaxies

    NASA Astrophysics Data System (ADS)

    Kemp, S. N.; Pérez-Hernández, Ernesto; Ramírez-Siordia, Víctor Hugo

    2016-02-01

    We have carried out photometry and spectroscopy on a sample of 10 cD galaxies. The photometry shows, in general, fairly flat and red profile colours, implying an envelope with the same stellar population as the central galaxy. This may indicate a possible primordial origin for both structures, consistent with ideas of downsizing. Preliminary spectroscopic results are generally in agreement with the photometry, with for example younger populations at large radii for A2199, but A2589 has only younger populations.

  18. Spectroscopic ellipsometry study of novel nanostructured transparent conducting oxide structures

    NASA Astrophysics Data System (ADS)

    Khosroabadi, Akram A.; Norwood, R. A.

    2013-02-01

    Spectroscopic ellipsometry has been used to find the optical constants, including refractive index, extinction coefficient, thickness and volume fraction of nanostructured transparent conducting oxides including indium tin oxide (ITO) and indium zinc oxide (IZO). We observed sharp features in the ellipsometry data, with the spectral peaks and positions depending on the nanostructure dimensions and material. A superposition of Lorentzian oscillators and the effective medium approximation has been applied to determine the volume ratio of voids and nanopillars, thereby providing the effective optical constants.

  19. Exploring How Substance Use Impedes Engagement along the HIV Care Continuum: A Qualitative Study.

    PubMed

    Gwadz, Marya; de Guzman, Rebecca; Freeman, Robert; Kutnick, Alexandra; Silverman, Elizabeth; Leonard, Noelle R; Ritchie, Amanda Spring; Muñoz-Plaza, Corinne; Salomon, Nadim; Wolfe, Hannah; Hilliard, Christopher; Cleland, Charles M; Honig, Sylvie

    2016-01-01

    Drug use is associated with low uptake of HIV antiretroviral therapy (ART), an under-studied step in the HIV care continuum, and insufficient engagement in HIV primary care. However, the specific underlying mechanisms by which drug use impedes these HIV health outcomes are poorly understood. The present qualitative study addresses this gap in the literature, focusing on African-American/Black and Hispanic persons living with HIV (PLWH) who had delayed, declined, or discontinued ART and who also were generally poorly engaged in health care. Participants (N = 37) were purposively sampled from a larger study for maximum variation on HIV indices. They engaged in 1-2 h audio-recorded in-depth semi-structured interviews on HIV histories guided by a multilevel social-cognitive theory. Transcripts were analyzed using a systematic content analysis approach. Consistent with the existing literature, heavy substance use, but not casual or social use, impeded ART uptake, mainly by undermining confidence in medication management abilities and triggering depression. The confluence of African-American/Black or Hispanic race/ethnicity, poverty, and drug use was associated with high levels of perceived stigma and inferior treatment in health-care settings compared to their peers. Furthermore, providers were described as frequently assuming participants were selling their medications to buy drugs, which strained provider-patient relationships. High levels of medical distrust, common in this population, created fears of ART and of negative interactions between street drugs and ART, but participants could not easily discuss this concern with health-care providers. Barriers to ART initiation and HIV care were embedded in other structural- and social-level challenges, which disproportionately affect low-income African-American/Black and Hispanic PLWH (e.g., homelessness, violence). Yet, HIV management was cyclical. In collaboration with trusted providers and ancillary staff

  20. Exploring How Substance Use Impedes Engagement along the HIV Care Continuum: A Qualitative Study

    PubMed Central

    Gwadz, Marya; de Guzman, Rebecca; Freeman, Robert; Kutnick, Alexandra; Silverman, Elizabeth; Leonard, Noelle R.; Ritchie, Amanda Spring; Muñoz-Plaza, Corinne; Salomon, Nadim; Wolfe, Hannah; Hilliard, Christopher; Cleland, Charles M.; Honig, Sylvie

    2016-01-01

    Drug use is associated with low uptake of HIV antiretroviral therapy (ART), an under-studied step in the HIV care continuum, and insufficient engagement in HIV primary care. However, the specific underlying mechanisms by which drug use impedes these HIV health outcomes are poorly understood. The present qualitative study addresses this gap in the literature, focusing on African-American/Black and Hispanic persons living with HIV (PLWH) who had delayed, declined, or discontinued ART and who also were generally poorly engaged in health care. Participants (N = 37) were purposively sampled from a larger study for maximum variation on HIV indices. They engaged in 1–2 h audio-recorded in-depth semi-structured interviews on HIV histories guided by a multilevel social-cognitive theory. Transcripts were analyzed using a systematic content analysis approach. Consistent with the existing literature, heavy substance use, but not casual or social use, impeded ART uptake, mainly by undermining confidence in medication management abilities and triggering depression. The confluence of African-American/Black or Hispanic race/ethnicity, poverty, and drug use was associated with high levels of perceived stigma and inferior treatment in health-care settings compared to their peers. Furthermore, providers were described as frequently assuming participants were selling their medications to buy drugs, which strained provider–patient relationships. High levels of medical distrust, common in this population, created fears of ART and of negative interactions between street drugs and ART, but participants could not easily discuss this concern with health-care providers. Barriers to ART initiation and HIV care were embedded in other structural- and social-level challenges, which disproportionately affect low-income African-American/Black and Hispanic PLWH (e.g., homelessness, violence). Yet, HIV management was cyclical. In collaboration with trusted providers and ancillary staff

  1. [Multifrequency impedance audiometry and study of occupational deafness: "Teflag", a new test].

    PubMed

    Camicas Vangout, M; Négrevergne, M

    1996-01-01

    The mechanical acoustic theory compares the annular ligament of the stapes to an elastic plot; plot # 2. The coupled stapedial muscle and annular ligament partly ensure the dampening of acoustic impulses (low frequencies in particular) and helped by the stapes footplate, their transmission, by hydraulic pressure to the liquids of the cochlea. This muscle ligament couple represents the true impedance adaptor for the middle ear region. So as to study plot # 2 we have set up a test, called Teflag, using the otoadmittancemetre produced by Grason Stadler. This apparatus enables us to measure the functional state of the ligament (by the study of susceptance, representing the inverse of the reactive forces linked to the inertial mass of the system and to its compliance; in fact that of the ligament. We can also measure the level of the resistive intra-cochlear forces and those of the annular ligament (the study of conductance). Our study compares 25 normal hearing patients and 64 ears with professional deafness. The Teflag gives us an evaluation of the functional state of the annular ligament, from morphological abnormalities of susceptance. Age induced hearing loss differs from professional deafness. A classification into 5 stages has been established following evaluation of functional annular ligament pathology. There is no hearing without oscillation (of a molecular order) of this ligament, which clearly seems to be the key point of the receptor organ, and ensures the detection of sound. PMID:9183915

  2. A Raman Spectroscopic Study of Kernite to 25 GPa

    NASA Astrophysics Data System (ADS)

    Silva, M. E.; O'Bannon, E. F., III; Williams, Q. C.

    2015-12-01

    A Raman spectroscopic study of kernite to 25 GPaMarcus Silva, Earl O'Bannon III, and Quentin Williams Department of Earth & Planetary Sciences, University of California Santa Cruz The Raman spectrum of kernite (Na2B4O6(OH)2·3(H2O)) has been characterized up to ~25 GPa in order to explore pressure-induced changes in a structurally novel mineral that contains mixed coordination borate groups (three- and four-fold), and both hydroxyl units and water. During compression, all of the ~30 modes monitored shift positively and monotonically until ~2.2 GPa where a few low frequency modes disappear and tetrahedral borate modes merge. The low frequency modes that disappear at ~2.2 GPa are likely associated with Na vibrations, and their disappearance suggests that dramatic changes occur in the Na sites at ~2.2 GPa. The merging of the boron bending and stretching modes at ~2.2 GPa suggests that the local symmetry of the BO4 tetrahedra changes at this pressure, and likely becomes more symmetric. The remaining modes shift positively up to ~7.4 GPa where a second notable change occurs. All but 5 modes (with initial frequencies of 150, 166, 289, 307, and 525 cm-1) disappear at ~7.4 GPa. This indicates that a second phase transition has occurred which affects both the BO3H and BO4­ groups: based on the loss of modes, this transition may be associated with disordering of the crystal. These 5 modes persist and shift monotonically up to ~25 GPa. On decompression, the 5 modes shift smoothly down to ~2.0 GPa where a few new modes appear in the spectrum. When fully decompressed to room pressure, the Raman spectrum of the recovered sample is significantly different from the ambient spectrum of the initial sample. Thus, our results are suggest a phase transition occurring at 2.2 GPa with changes in the Na and tetrahedral boron sites, followed by an additional transition at 7.4 GPa that may involve disordering of the crystal. In the latter transition, at least the BO3H groups appear to be

  3. Spectroscopic studies of gas-phase molecular clusters

    NASA Astrophysics Data System (ADS)

    Wong, Chi-Kin

    Spectroscopic investigations of hydrogen-bonding and van der Waals' interactions in molecular clusters were studied by the techniques of infrared predissociation and resonance-enhanced multiphoton ionization spectroscopies (REMPI). Ab initio calculations were applied in conjunction for data interpretation. The infrared predissociation spectroscopy of CN-·(H 2O)n (n = 2--6) clusters was reported in the region of 2950--3850 cm-1. The hydrogen bondings for the C-site and N-site binding, and among the water molecules were identified for n = 2 to 4. A spectral transition was observed for n = 5 and 6, implying that the anion was surface-bound onto the water aggregates in larger clusters. The infrared predissociation spectroscopy of Br-·(NH 3) and I-·(NH3) n (n = 1--3) clusters was reported in the region of 3050--3450 cm-1. For the Br -·(NH3) complex, a dominating ionic NH stretch appeared at 3175 cm-1, and the weaker free NH stretch appeared at 3348 cm-1. The observed spectrum was consistent to the structure in which there was one nearly linear hydrogen bond between Br- and the NH3 moiety. For the I- ·(NH3) complex, five distinct IR absorption bands were observed in the spectrum. The spectrum was not consistent with basic frequency patterns of three geometries considered in the ab initio calculations---complex with one, two and three hydrogen bondings between I- and the NH3 moiety. Substantial inhomogenous broadening were displayed in the spectra for I- ·(NH3)n (n = 2--3), suggesting the presence of multiple isomers. The REMPI spectroscopy of the bound 4p 2pi 1/2 and 2pi3/2 states, and the dissociative 3d 2Sigma+1/2 state in the Al·Ar complex was reported. The dissociative spectrum at Al+ channel suggested the coupling of the 4p 2pi 1/2,3/2 states to the repulsive 3d 2Sigma+1/2 state. The spin-electronic coupling was further manifested in the dissociative Al+ spectrum of the 3d 2Sigma+1/2 state. Using the potential energy curves obtained from ab initio

  4. NMR spectroscopic study of organic phosphate esters coprecipitated with calcite

    NASA Astrophysics Data System (ADS)

    Phillips, Brian L.; Zhang, Zelong; Kubista, Laura; Frisia, Silvia; Borsato, Andrea

    2016-06-01

    Organic phosphorus incorporated in calcite during laboratory precipitation experiments and in natural cave deposits was investigated by solid-state NMR spectroscopy. For calcite precipitated in the presence of organic phosphoesters of varying size and functionality, solid-state 31P{1H} CP/MAS NMR shows that the phosphoesters were incorporated intact into the solid. Systematic changes in the 31P NMR chemical shift of the phosphate group were observed between the solid phosphoester and that incorporated in the solid precipitate, yielding 31P NMR chemical shifts of the coprecipitates in the range of +1.8 to -2.2 ppm. These chemical shifts are distinct from that of similarly prepared calcite coprecipitated with inorganic phosphate, 3.5 ppm. Only minor changes were noted in the phosphoester 31P chemical shift anisotropy (CSA) which suggests no significant change in the local structure of the phosphate group, which is dominated by C-O-P bonding. Close spatial proximity of the organic phosphate group to calcite structural components was revealed by 31P/13C rotational echo double resonance (REDOR) experiments for coprecipitates prepared with 13C-labeled carbonate. All coprecipitates showed significant 31P dephasing effects upon 13C-irradiation, signaling atomic-scale proximity to carbonate carbon. The dephasing rate for smaller organophosphate molecules is similar to that observed for inorganic phosphate, whereas much slower dephasing was observed for larger molecules having long and/or bulky side-chains. This result suggests that small organic molecules can be tightly enclosed within the calcite structure, whereas significant structural disruption required to accommodate the larger organic molecules leads to longer phosphate-carbonate distances. Comparison of 31P NMR spectroscopic data from the synthetic coprecipitates with those from calcite moonmilk speleothems indicates that phosphorus occurs mainly as inorganic orthophosphate in the natural deposits, although small

  5. Assessing Bolus Retention in Achalasia using High Resolution Manometry with Impedance: A Comparator Study with Timed Barium Esophagram

    PubMed Central

    Cho, Yu K.; Lipowska, Anna M.; Nicodème, Frédéric; Teitelbaum, Ezra N.; Hungness, Eric S.; Johnston, Elyse R.; Gawron, Andrew; Kahrilas, Peter J.; Pandolfino, John E.

    2014-01-01

    Background The aim of this study was to assess whether high-resolution impedance-manometry (HRIM) could be utilized to assess bolus retention similar to the timed barium esophagram (TBE). Method 20 achalasia patients [10 males, ages 21–79] were prospectively evaluated with HRIM and TBE to determine the correlation between barium column height and the impedance bolus height (IBH). The TBE protocol utilized a 200 ml barium challenge and the HRIM protocol utilized a 200 ml saline challenge protocol. Both protocols were performed in an upright position and the heights of the barium and impedance columns were measured at 1 and 5 minutes. Analysis of IBH was performed with a topographic technique and a spatial impedance variation plot. Results There was no significant difference between the median IBH and barium column at 1 minute [IBH 12.0 cm (IQR, 8.0–18.0), TBE 12.0 cm (IQR, 7.0–19.0), P=0.90] or 5 minutes [IBH 11.0 cm (IQR, 1.0–17.0), TBE 9.0 cm (IQR, 4.0–12.0), P=0.47]. Additionally, the correlation between the two measurements at 1 and 5 minutes was 0.60 and 0.86, respectively. Using a barium column or impedance height of >5.0 as a definition of bolus retention was associated with 75% concordance at 1 minute and 95% concordance at 5 minutes. Conclusion There was excellent agreement between TBE and HRIM for assessing bolus retention at 5 minutes. Thus, HRM with impedance may be utilized as a single test to assess bolus retention and motor function in the management of achalasia. PMID:24710506

  6. Feasibility studies of electrical impedance spectroscopy for monitoring tissue response to photodynamic therapy

    NASA Astrophysics Data System (ADS)

    Wilson, Brian C.; Osterman, Kendra S.; Hoopes, P. Jack; Lilge, Lothar D.; Paulsen, Keith D.

    1998-05-01

    Electrical impedance spectroscopy (EIS) has been evaluated as a non- or minimally-invasive technique to monitor the acute tissue response to photodynamic therapy (PDT). In this study the EIS spectra of normal muscle tissue in the rat hind leg were monitored immediately before and at time intervals up to 96 hours post-PDT treatment with different photosensitizers (Photofrin, ALA-induced PpIX, BenzoPorphyrin Derivative), at varying photosensitizer and light doses. EIS measurements were made using a pair of solid matrix Ag-AgCl electrodes placed parallel to one another on either side of the muscle mass and interfaced to a precision LCR impedance meter scanning the frequency range 1 - 1000 KHz. Independent histological grading of tissue injury was performed on tissue sections from treated and untreated legs at the 96 hour end point. Significant and PDT dose-dependent changes in the EIS spectra following treatment were observed, including increases in conductivity which correlated with the immediate post-PDT edematous response with Photofrin and ALA and which resolved or partially-resolved over the measurement time course. Photofrin treatments exhibited a clear drug dose response at 96 hours that was evident in both the EIS spectra and the histological sections. These changes included significant tissue necrosis as well as edema, inflammation and early fibroplasia. The BPD data were less clear, but potentially quite interesting. Most striking were below unity ratios of treated-to-untreated muscle spectra components at 24 hours which reversed to above unity by 96 hours in the through skin measurements. This phenomenon is indicative of a tissue response distinctly different than that observed with Photofrin or ALA. These data also suggest that EIS measured changes are sensitive enough to detect differences in PDT-initiated tissue damage that may be photosensitize-specific. While the data are derived from a small number of animals, the findings are quite encouraging in

  7. Urinary Creatinine Excretion, Bioelectrical Impedance Analysis, and Clinical Outcomes in Patients with CKD: The CRIC Study

    PubMed Central

    Xie, Dawei; Anderson, Amanda H.; Leonard, Mary B.; Reese, Peter P.; Delafontaine, Patrice; Horwitz, Edward; Kallem, Radhakrishna; Navaneethan, Sankar; Ojo, Akinlolu; Porter, Anna C.; Sondheimer, James H.; Sweeney, H. Lee; Townsend, Raymond R.; Feldman, Harold I.

    2014-01-01

    Background and objectives Previous studies in chronic disease states have demonstrated an association between lower urinary creatinine excretion (UCr) and increased mortality, a finding presumed to reflect the effect of low muscle mass on clinical outcomes. Little is known about the relationship between UCr and other measures of body composition in terms of the ability to predict outcomes of interest. Design, setting, participants, & measurements Using data from the Chronic Renal Insufficiency Cohort (CRIC), the relationship between UCr, fat free mass (FFM) as estimated by bioelectrical impedance analysis, and (in a subpopulation) whole-body dual-energy x-ray absorptiometry assessment of appendicular lean mass were characterized. The associations of UCr and FFM with mortality and ESRD were compared using Cox proportional hazards models. Results A total of 3604 CRIC participants (91% of the full CRIC cohort) with both a baseline UCr and FFM measurement were included; of these, 232 had contemporaneous dual-energy x-ray absorptiometry measurements. Participants were recruited between July 2003 and March 2007. UCr and FFM were modestly correlated (rho=0.50; P<0.001), while FFM and appendicular lean mass were highly correlated (rho=0.91; P<0.001). Higher urinary urea nitrogen, black race, younger age, and lower serum cystatin C level were all significantly associated with higher UCr. Over a median (interquartile range) of 4.2 (3.1–5.0) years of follow-up, 336 (9.3%) participants died and 510 (14.2%) reached ESRD. Lower UCr was associated with death and ESRD even after adjustment for FFM (adjusted hazard ratio for death per 1 SD higher level of UCr, 0.63 [95% confidence interval, 0.56 to 0.72]; adjusted hazard ratio for ESRD per 1 SD higher level of UCr, 0.70 [95% confidence interval, 0.63 to 0.75]). Conclusions Among a cohort of individuals with CKD, lower UCr is associated with death and ESRD independent of FFM as assessed by bioelectrical impedance analysis. PMID

  8. Picosecond flash spectroscopic studies on ultraviolet stabilizers and stabilized polymers

    NASA Technical Reports Server (NTRS)

    Scott, G. W.

    1982-01-01

    Spectroscopic and excited state decay kinetics are reported for monomeric and polymeric forms of ultraviolet stabilizers in the 2-(2'-hydroxyphenyl)-benzotriazole and 2-hydroxybenzophenone classes. For some of these molecules in various solvents at room temperature, (1) ground state absorption spectra, (2) emission spectra, (3) picosecond time-resolved transient absorption spectra, (4) ground state absorption recovery kinetics, (5) emission kinetics, and (6) transient absorption kinetics are reported. In the solid state at low temperatures, emission spectra and their temperature dependent kinetics up to approximately 200K as well as, in one case, the 12K excitation spectra of the observed dual emission are also reported.

  9. Resonance Raman spectroscopic studies of enzymesubstrate intermediates at 5 K

    NASA Astrophysics Data System (ADS)

    Kim, Munsok; Carey, Paul R.

    1991-01-01

    A simple and versatile system for resonance Raman (RR) spectroscopic analysis of enzymesubstrate complexes at liquid helium temperatures is described. The system allows us to record high-quality RR spectra for dithioacyl papain intermediates (MeO-Phe-Gly- and MeO-Gly-Gly-Phe-Gly-C (dbnd S)S-papain) in ice matrices at 5 K. Based on established structure-spectra correlations, it is concluded that the active-site conformation of the intermediates about the φ', ψ' glycinic linkages and cysteine-25 side chain is B-G+-PH both in ice matrices at 5 K and in solution at room temperature.

  10. Spectroscopic study of the extremely fast rotating star 44 Geminorum

    NASA Astrophysics Data System (ADS)

    Iliev, L.; Vennes, S.; Kawka, A.; Kubat, J.; Nemeth, P.; Borisov, G.; KRaus, M.

    Stars with extremely fast rotation represent interesting challenge to modern understanding of the stellar evolution. The reasons why such a spin-up process should occur during the evolution to otherwise normal star are still not well understood. Already in the beginning of the XX century Otto Struve proposed that fast rotation of the group of stars spectroscopically classified as Be could be the main reason for the formation of observed disks of circumstellar material around them. This circumstellar material is responsible for the emission lines observed in the spectrum of Be-stars as well as for the whole complex of spectral and photometrical patterns called in general Be-phenomenon.

  11. IR spectroscopic study of the chemical composition of epiphytic lichens

    NASA Astrophysics Data System (ADS)

    Meysurova, A. F.; Khizhnyak, S. D.; Pakhomov, P. M.

    2011-11-01

    Changes in the chemical composition of lichens exposed to pollutants are investigated by means of FTIR spectroscopy. According to model experiments, alkyl nitrates, ammonium salts, amines, and sulfones develop in the lichen thallus through the action of ammonia and nitric and sulfuric acids. Spectroscopic data of modeling experiments enabled nitrogen- and sulfur-containing substances to be identified as the main air pollutants in the vicinity of a pig-breeding complex and information to be obtained on the content of the pollutants and their impact on the lichens.

  12. Skin-impedance in Fabry Disease: A prospective, controlled, non-randomized clinical study

    PubMed Central

    Gupta, Surya N; Ries, Markus; Murray, Gary J; Quirk, Jane M; Brady, Roscoe O; Lidicker, Jeffrey R; Schiffmann, Raphael; Moore, David F

    2008-01-01

    Background We previously demonstrated improved sweating after enzyme replacement therapy (ERT) in Fabry disease using the thermo-regularity sweat and quantitative sudomotor axon reflex tests. Skin-impedance, a measure skin-moisture (sweating), has been used in the clinical evaluation of burns and pressure ulcers using the portable dynamic dermal impedance monitor (DDIM) system. Methods We compared skin impedance measurements in hemizygous patients with Fabry disease (22 post 3-years of bi-weekly ERT and 5 ERT naive) and 22 healthy controls. Force compensated skin-moisture values were used for statistical analysis. Outcome measures included 1) moisture reading of the 100th repetitive reading, 2) rate of change, 3) average of 60–110th reading and 4) overall average of all readings. Results All outcome measures showed a significant difference in skin-moisture between Fabry patients and control subjects (p < 0.0001). There was no difference between Fabry patients on ERT and patients naïve to ERT. Increased skin-impedance values for the four skin-impedance outcome measures were found in a small number of dermatome test-sites two days post-enzyme infusions. Conclusion The instrument portability, ease of its use, a relatively short time required for the assessment, and the fact that DDIM system was able to detect the difference in skin-moisture renders the instrument a useful clinical tool. PMID:18990229

  13. Assessing the applicability of the earth impedance method for in situ studies of tree root systems

    PubMed Central

    Urban, Josef; Bequet, Raphael; Mainiero, Raphael

    2011-01-01

    Several electrical methods have been introduced as non-invasive techniques to overcome the limited accessibility to root systems. Among them, the earth impedance method (EIM) represents the most recent development. Applying an electrical field between a cormus and the rooted soil, the EIM measures the absorptive root surface area (ARSA) from grounding resistance patterns. Allometric relationships suggested that this method was a valuable tool. Crucial assumptions for the applicability of the EIM, however, have not been tested experimentally. Focusing on tree root systems, the present study assesses the applicability of the EIM. Six hypotheses, deduced from the EIM approach, were tested in several experiments and the results were compared with conventional methods. None of the hypotheses could be verified and the results allow two major conclusions. First, in terms of an analogue electrical circuit, a tree-root–soil continuum appears as a serial circuit with xylem and soil resistance being the dominant components. Allometric variation in contact resistance, with the latter being the proxy for root surface area, are thus overruled by the spatial and seasonal variation of soil and xylem resistances. Second, in a tree-root–soil continuum, distal roots conduct only a negligible portion of the electric charge. Most of charge carriers leave the root system in the proximal parts of the root–soil interface. PMID:21273337

  14. Impedance Spectroscopy and Electroabsorption Studies of PCPDTBT-PCBM Bulk-Heterojunction Solar Cells

    NASA Astrophysics Data System (ADS)

    Green, Christopher; Cohick, Zane; Tzolov, Marian

    2014-03-01

    Bulk heterojunction polymer solar cells, consisting of PCPDTBT and PCBM, offer the potential for high light absorption and effective charge collection in sub-micron thick films. An understanding of the behavior of photo-generated charge transfer complexes in the polymer/small molecule blend is needed for further increases in the efficiency of such devices. In this study, we present experimental results on impedance spectroscopy indicating the formation of trapped electrical charges upon illumination. The population of the related energy states depends on the applied voltage. These results are supported by electroabsorption spectroscopy of the solar cells and of the films of the constituting materials. They indicate an additional electroabsorption feature not present in the individual films of the PCPDTBT and PCBM. The voltage dependence of the electroabsorption signal resulted in estimation of the built-in voltage in our solar cells of 1.1 eV. Our comparison of the photocurrent spectrum with the optical absorption spectrum of the solar cells indicate more efficient energy conversion for the light absorbed in the PCPDTBT compared to the light absorbed in PCBM.

  15. High Resistivity Lipid Bilayers Assembled on Polyelectrolyte Multilayer Cushions: An Impedance Study.

    PubMed

    Diamanti, Eleftheria; Gregurec, Danijela; Rodríguez-Presa, María José; Gervasi, Claudio A; Azzaroni, Omar; Moya, Sergio E

    2016-06-28

    Supported membranes on top of polymer cushions are interesting models of biomembranes as cell membranes are supported on a polymer network of proteins and sugars. In this work lipid vesicles formed by a mixture of 30% 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 70% 1,2-dioleoyl-sn-glycero-3-phospho-l-serine (DOPS) are assembled on top of a polyelectrolyte multilayer (PEM) cushion of poly(allylamine hydrochloride) (PAH) and poly(styrene sodium sulfonate) (PSS). The assembly results in the formation of a bilayer on top of the PEM as proven by means of the quartz crystal microbalance with dissipation technique (QCM-D) and by cryo-transmission electron microscopy (cryo-TEM). The electrical properties of the bilayer are studied by electrochemical impedance spectroscopy (EIS). The bilayer supported on the PEMs shows a high resistance, on the order of 10(7) Ω cm(2), which is indicative of a continuous, dense bilayer. Such resistance is comparable with the resistance of black lipid membranes. This is the first time that such values are obtained for lipid bilayers supported on PEMs. The assembly of polyelectrolytes on top of a lipid bilayer decreases the resistance of the bilayer up to 2 orders of magnitude. The assembly of the polyelectrolytes on the lipids induces defects or pores in the bilayer which in turn prompts a decrease in the measured resistance. PMID:27267089

  16. Biological capacitance studies of anodes in microbial fuel cells using electrochemical impedance spectroscopy.

    PubMed

    Lu, Zhihao; Girguis, Peter; Liang, Peng; Shi, Haifeng; Huang, Guangtuan; Cai, Lankun; Zhang, Lehua

    2015-07-01

    It is known that cell potential increases while anode resistance decreases during the start-up of microbial fuel cells (MFCs). Biological capacitance, defined as the apparent capacitance attributed to biological activity including biofilm production, plays a role in this phenomenon. In this research, electrochemical impedance spectroscopy was employed to study anode capacitance and resistance during the start-up period of MFCs so that the role of biological capacitance was revealed in electricity generation by MFCs. It was observed that the anode capacitance ranged from 3.29 to 120 mF which increased by 16.8% to 18-20 times over 10-12 days. Notably, lowering the temperature and arresting biological activity via fixation by 4% para formaldehyde resulted in the decrease of biological capacitance by 16.9 and 62.6%, indicating a negative correlation between anode capacitance and anode resistance of MFCs. Thus, biological capacitance of anode should play an important role in power generation by MFCs. We suggest that MFCs are not only biological reactors and/or electrochemical cells, but also biological capacitors, extending the vision on mechanism exploration of electron transfer, reactor structure design and electrode materials development of MFCs. PMID:25656699

  17. Comparative Study of Impedance Eduction Methods. Part 1; DLR Tests and Methodology

    NASA Technical Reports Server (NTRS)

    Busse-Gerstengarbe, Stefan; Bake, Friedrich; Enghardt, Lars; Jones, Michael G.

    2013-01-01

    The absorption efficiency of acoustic liners used in aircraft engines is characterized by the acoustic impedance. World wide, many grazing ow test rigs and eduction methods are available that provide values for that impedance. However, a direct comparison and assessment of the data of the di erent rigs and methods is often not possible because test objects and test conditions are quite di erent. Only a few papers provide a direct comparison. Therefore, this paper together with a companion paper, present data measured with a reference test object under similar conditions in the DLR and NASA grazing ow test rigs. Additionally, by applying the in-house methods Liner Impedance Non-Uniform ow Solving algorithm (LINUS, DLR) and Convected Helmhholtz Equation approach (CHE, NASA) on the data sets, similarities and differences due to underlying theory are identi ed and discussed.

  18. Crew Quarters (CQ) and Electromagnetic Interference (EMI) Measurement Facility Combined Impedance Study

    NASA Technical Reports Server (NTRS)

    Scully, Robert C.

    2011-01-01

    This report documents an investigation into observed failures associated with conducted susceptibility testing of Crew Quarters (CQ) hardware in the Johnson Space Center (JSC) Electromagnetic Interference (EMI) Measurement Facility, and the work accomplished to identify the source of the observed behavior. Investigation led to the conclusion that the hardware power input impedance was interacting with the facility power impedance leading to instability at the observed frequencies of susceptibility. Testing performed in other facilities did not show this same behavior, pointing back to the EMI Measurement Facility power as the potential root cause. A LISN emulating the Station power bus impedance was inserted into the power circuit, and the susceptibility was eliminated from the measurements.

  19. Synthesis and characterization of cancrinite-type zeolite, and its ionic conductivity study by AC impedance analysis

    NASA Astrophysics Data System (ADS)

    Kriaa, A.; Ben Saad, K.; Hamzaoui, A. H.

    2012-12-01

    The synthesis of cancrinite in the system NaOH-SiO2-Al2O3-NaHCO3-H2O was performed, according to methods described in the literature, in an autoclave under hydrothermal conditions at T = 473 K. The electrical properties of cancrinite-type zeolite pellets were investigated by complex impedance spectroscopy in the temperature range 465-800°C. The effect of temperature on impedance parameters was studied using an impedance analyzer in a wide frequency range (1 Hz to 13 MHz). The real and imaginary parts of complex impedance trace semicircles in the complex plane are plotted. The bulk resistance of the material decreases with rise in temperature. This exhibits a typical negative temperature coefficient of resistance (NTCR) behavior of the material. The results of bulk electrical conductivity and its activation energy are presented. The modulus analysis suggests that the electrical transport processes in the material are very likely to be of electronic nature. Relaxation frequencies follow an Arrhenius behavior with activation energy values not comparable to those found for the electrical conductivity.

  20. Study the effects of moisture content on the electrical properties of technical textiles by impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Lusis, A.; Pentjuss, E.; Bajars, G.; Gabrusenoks, J.; Janeliukštis, R.; Zandersons, J.

    2012-08-01

    Application of metal coatings for the functionalization of technical fibres and fabrics faced with influence of moisture on functional properties, e.g., the impedance of the metal coated K-glass fabrics have strong dependence of content absorbed water or moisture. The paper devoted to develop methodology for characterisation functional materials based on fabrics and model for interpretation of the electrical impedance spectra to obtained functional characteristics of technical textile fabrics. Model based on analyses of 3D plot of imaginary part of complex modulus spectra versus sample mass. Methodology helps to control content of adsorbed water in fabric and influence of moisture on the functional characteristics.

  1. Impedance spectroscopy study of anodic growth of zirconium oxide film in NaOH medium

    NASA Astrophysics Data System (ADS)

    Pauporté, T.; Finne, J.; Lincot, D.

    2005-06-01

    The growth of anodic oxide films on zirconium metal has been followed up to 300 V by electrochemical impedance spectroscopy and scanning electron microscopy. The maximum layer thickness is 720 nm, the dielectric constant of the film is measured at 19.5 and the growth constant is 2.4 nm V-1. Above 50 V, the presence of two impedance relaxations between 1 Hz and 200 kHz reveals a bilayered structure. This may be a consequence of a lower resistivity of the outer layer induced by some electrolytic solution infiltration into film defects.

  2. Impedance spectroscopic analysis on effects of partial oxidation of TiN bottom electrode and microstructure of amorphous and crystalline HfO2 thin films on their bipolar resistive switching.

    PubMed

    Yoon, Ji-Wook; Yoon, Jung Ho; Lee, Jong-Heun; Hwang, Cheol Seong

    2014-06-21

    The electrical resistance switching (RS) properties of amorphous HfO2 (a-HfO2) and crystalline HfO2 (c-HfO2) thin films grown on a TiN substrate via atomic layer deposition were examined using DC current-voltage (I-V) sweep and AC impedance spectroscopic (IS) analyses. The rapid thermal annealing of the a-HfO2 film at 500 °C under a N2 atmosphere for 5 min crystallized the HfO2 film and induced an interfacial TiON barrier layer. The a-HfO2 sample showed fluent bipolar RS performance with a high on/off ratio (∼ 500), whereas the c-HfO2 sample showed a much lower on/off ratio (<∼ 10), but its switching uniformity was better than that of a-HfO2. Such critical differences can be mainly attributed to the absence and presence of the TiON barrier layer in the a-HfO2 and c-HfO2 samples, respectively. The AC IS especially enabled the resistance states of the HfO2/Pt interface and the HfO2/TiN interface to be separately examined during one complete switching cycle of each sample. Although the Pt/c-HfO2 interface has a Schottky barrier in the pristine state, it disappeared once the c-HfO2 was electroformed and was not recovered even after the reset step. In contrast, the Pt/a-HfO2 interface partly recovered the Schottky barrier after the reset. PMID:24817626

  3. Esophageal Bolus Transit in Newborns with Gastroesophageal Reflux Disease Symptoms: A Multichannel Intraluminal Impedance Study

    PubMed Central

    Liguori, Stefania Alfonsina; Maggiora, Elena; Locatelli, Emanuela; Indrio, Flavia; Bertino, Enrico; Coscia, Alessandra

    2015-01-01

    Purpose The aim of this study was to evaluate bolus transit during esophageal swallow (ES) and gastroesophageal reflux (GER) events and to investigate the relationship between the characteristics of ES and GER events in a population of term and preterm newborns with symptoms of gastroesophageal reflux disease (GERD). Methods The study population consisted of term and preterm newborns referred to combined multichannel intraluminal impedance (MII) and pH monitoring for GERD symptoms. The frequency and characteristics of ES and GER events were assessed by two independent investigators. Statistical significance was set at p<0.05. Results Fifty-four newborns (23 preterm) were included in the analyses. Median bolus head advancing time corrected for esophageal length (BHATc) was shorter during mealtime than during the postprandial period (median, interquartile range): 0.20 (0.15-0.29) s/cm vs. 0.47 (0.39-0.64) s/cm, p<0.001. Median bolus presence time (BPT) was prolonged during mealtime: 4.71(3.49-6.27) s vs. 2.66 (1.82-3.73) s, p<0.001. Higher BHATc (p=0.03) and prolonged BPT (p<0.001) were observed in preterm newborns during the postprandial period. A significant positive correlation between BHATc and bolus clearance time was also observed (ρ=0.33, p=0.016). Conclusion The analysis of ES and GER events at the same time by MII provides useful information to better understand the physiopathology of GERD. In particular, the analysis of BHATc during the postprandial period could help clinicians identify newborns with prolonged esophageal clearance time due to impaired esophageal motility, which could allow for more accurate recommendations regarding further tests and treatment. PMID:26770898

  4. A spectroscopic study of uranium(VI) interaction with magnetite

    NASA Astrophysics Data System (ADS)

    Aamrani, S. El; Giménez, J.; Rovira, M.; Seco, F.; Grivé, M.; Bruno, J.; Duro, L.; de Pablo, J.

    2007-08-01

    The uranium sorbed onto commercial magnetite has been characterized by using two different spectroscopic techniques such as X-ray photoelectron spectroscopy (XPS), and extended X-ray absorption fine structure (EXAFS). Magnetite samples have been put in contact with uranium(VI) solutions in conditions in which a high uranium uptake is expected. After several days, the magnetite surface has been analysed by XPS and EXAFS. The XPS results obtained are not conclusive regarding the uranium oxidation state in the magnetite surface. On the other hand, the results obtained with the EXAFS technique show that the uranium-magnetite sample spectrum has characteristics from both the UO 2 and schoepite spectra, e.g. a relatively high coordination number of equatorial oxygens and two axial oxygens, respectively. These results would indicate that the uranium sorbed onto magnetite would be a mixture of uranium(IV) and uranium(VI).

  5. Spectroscopic study of carbonaceous dust particles grown in benzene plasma

    SciTech Connect

    Lee, Szetsen; Chen, H.-F.; Chin, C.-J.

    2007-06-01

    Carbonaceous dust particles have been synthesized from benzene using an rf glow discharge. Scanning electron microscope inspection revealed that the plasma-synthesized dust particles can be classified into two types. Shell-structured dust particles showed a wide size distribution from 3 to40 {mu}m. The other type, with different degrees of aggregation, appeared to be dense and spherical with a very distinctive yellow color and size distribution from 100 nm to 2 {mu}m. Analyses using micro-Raman and Fourier transform infrared microscopy indicated that the main components of the dust particles are polyphenyls and hydrogenated amorphous carbon (HAC). The luminescence background in Raman spectra and the infrared C-H stretching vibrational features observed around 3.4 {mu}m for the dust particles are attributed to HAC. The formation mechanisms and spectroscopic characterization of carbonaceous dust particles are discussed.

  6. Spectroscopic intravascular photoacoustic imaging of neovasculature: phantom studies

    NASA Astrophysics Data System (ADS)

    Su, Jimmy L.; Wang, Bo; Emelianov, Stanislav Y.

    2009-02-01

    An acceleration of angiogenesis in the adventitial vasa-vasorum is usually associated with vulnerable, thin-cap fibroatheroma in atherosclerotic plaques. Angiogenesis creates microvasculature too small to be detected and differentiated using conventional imaging techniques. However, by using spectroscopic photoacoustic imaging, we take advantage of the wavelength-dependent optical absorption properties of blood. We used a vessel-mimicking phantom with micro blood vessels. The phantom was imaged with intravascular photoacoustic imaging across a range of wavelengths. The image intensities were cross-correlated with the known absorption spectra of blood. The resulting cross-correlation image was able to reveal the location of the artificial blood vessels differentiated from non-blood vessel components.

  7. Spectroscopic studies of superconductors. Part A: Infrared and Raman spectra

    SciTech Connect

    Bozovic, I.; Marel, D. van der

    1996-12-31

    During the ten years that followed the discovery of superconductivity above 30 K in lanthanum barium cuprate by Bednorz and Mueller, the condensed matter physics community has been engaged in an unprecedented worldwide effort in materials processing, characterization of physical properties, and theoretical modeling of superconductors. The present conference has brought together a group of researchers who are actively involved in the experimental determination of the physical properties of high-{Tc} superconductors, the quest for the microscopic mechanism (or mechanisms) of superconductivity, the search for new physical phenomena in these materials, or the search for new classes of superconducting materials. The distinguishing feature and the unifying theme of this conference was the use of spectroscopic techniques as the primary tools in pursuing these goals. Separate abstracts were prepared for 32 papers in this conference.

  8. In-situ spectroscopic studies of electrochromic tungsten oxide films

    NASA Astrophysics Data System (ADS)

    Ozer, Nilgun; Demirbas, Muharrem; Ozyurt, Secuk

    2001-11-01

    Tungsten oxide thin films were prepared using an ethanolic solution of tungsten hexachloride (WCl6) by sol-gel spin coating. The films were spin coated on indium tin oxide (ITO) coated glass substrate at temperatures in the range of 100 to 450 degree(s)C. The films were characterized by x-ray diffractometry (XRD), scanning electron microscopy (SEM) UV- visible spectroscopy and cyclic voltammetry (CV). XRD showed that they had a polycrystalline WO3 structure for heat treatment temperatures at above 350 degree(s)C. The SEM examinations showed that the surface texture was very uniform and homogeneous. In situ electrochemical reduction of WO3/ITO (2M HCl) produced a blue color in less than a second. Coloration efficiency (CE) was found to be 21 cm2/mC. In situ spectroscopic investigations showed that these films could be used as a working electrode in electrochromic devices.

  9. Single cell studies of mouse embryonic stem cell (mESC) differentiation by electrical impedance measurements in a microfluidic device.

    PubMed

    Zhou, Ying; Basu, Srinjan; Laue, Ernest; Seshia, Ashwin A

    2016-07-15

    Biological populations of cells show considerable cell-to-cell variability. Study of single cells and analysis of cell heterogeneity are considered to be critical in understanding biological processes such as stem cell differentiation and cancer development. Recent advances in lab-on-a-chip techniques have allowed single-cell capture in microfluidic channels with the possibility of precise environmental control and high throughput of experiments with minimal usage of samples and reagents. In recent years, label-free techniques such as electrical impedance spectroscopy have emerged as a non-invasive approach to studying cell properties. In this study, we have designed and fabricated a microfluidic device that combines hydrodynamic trapping of single cells in pre-defined locations with the capability of running electrical impedance measurements within the same device. We have measured mouse embryonic stem cells (mESCs) at different states during differentiation (t=0h, 24h and 48h) and quantitatively analysed the changes in electrical parameters of cells during differentiation. A marked increase in the magnitude of the cell impedance is found during cell differentiation, which can be attributed to an increase in cell size. The analysis of the measurements shows that the nucleus-to-cytoplasm ratio decreases during this process. The degree of cell heterogeneity is observed to be the highest when the cells are at the transition state (24h), compare with cells at undifferentiated (0h) and fully differentiated (48h) states. The device enables highly efficient single cell trapping and provides sensitive, label-free electrical impedance measurements of individual cells, enabling the possibility of quantitatively analysing their physical state as well as studying the associated heterogeneity of a cell population. PMID:26963790

  10. Single cell studies of mouse embryonic stem cell (mESC) differentiation by electrical impedance measurements in a microfluidic device

    PubMed Central

    Zhou, Ying; Basu, Srinjan; Laue, Ernest; Seshia, Ashwin A.

    2016-01-01

    Biological populations of cells show considerable cell-to-cell variability. Study of single cells and analysis of cell heterogeneity are considered to be critical in understanding biological processes such as stem cell differentiation and cancer development. Recent advances in lab-on-a-chip techniques have allowed single-cell capture in microfluidic channels with the possibility of precise environmental control and high throughput of experiments with minimal usage of samples and reagents. In recent years, label-free techniques such as electrical impedance spectroscopy have emerged as a non-invasive approach to studying cell properties. In this study, we have designed and fabricated a microfluidic device that combines hydrodynamic trapping of single cells in pre-defined locations with the capability of running electrical impedance measurements within the same device. We have measured mouse embryonic stem cells (mESCs) at different states during differentiation (t=0 h, 24 h and 48 h) and quantitatively analysed the changes in electrical parameters of cells during differentiation. A marked increase in the magnitude of the cell impedance is found during cell differentiation, which can be attributed to an increase in cell size. The analysis of the measurements shows that the nucleus-to-cytoplasm ratio decreases during this process. The degree of cell heterogeneity is observed to be the highest when the cells are at the transition state (24 h), compare with cells at undifferentiated (0 h) and fully differentiated (48 h) states. The device enables highly efficient single cell trapping and provides sensitive, label-free electrical impedance measurements of individual cells, enabling the possibility of quantitatively analysing their physical state as well as studying the associated heterogeneity of a cell population. PMID:26963790

  11. Spectroscopic ellipsometry studies of HF treated Si (100) surfaces

    NASA Technical Reports Server (NTRS)

    Yao, Huade; Woollam, John A.; Alterovitz, Samuel A.

    1993-01-01

    Both ex situ and in situ spectroscopic ellipsometry (SE) measurements were employed to investigate the effects of HF cleaning on Si surfaces. The hydrogen-terminated (H-terminated) Si surface was modeled as an equivalent dielectric layer, and monitored in real time by SE measurements. The SE analyses indicate that after a 20-s 9:1 HF dip without rinse, the Si(100) surface was passivated by the hydrogen termination and remained chemically stable. Roughness of the HF-etched bare Si(100) surface was observed, in an ultrahigh vacuum (UHV) chamber, and analyzed by the in situ SE. Evidence for desorption of the H-terminated Si surface-layer, after being heated to approximately 550 C in the UHV chamber, is presented and discussed. This is the first use of an ex situ and in situ real-time, nondestructive technique capable of showing state of passivation, the rate of reoxidation, and the surface roughness of the H-terminated Si surfaces.

  12. Spectroscopic ellipsometry studies of HF treated Si (100) surfaces

    NASA Technical Reports Server (NTRS)

    Yao, Huade; Woollam, John A.; Alterovitz, Samuel A.

    1993-01-01

    Both ex situ and in situ spectroscopic ellipsometry (SE) measurements were employed to investigate the effect of HF cleaning on Si surfaces. The hydrogen-terminated (H-terminated) Si surface was modeled as an equivalent dielectric layer, and monitored in real time by SE measurements. The SE analyses indicate that, after a 20-sec 9:1 HF dip without rinse, the Si (100) surface was passivated by the hydrogen termination and remained chemically stable. Roughness of the HF-etched bare Si (100) surface was observed, in an ultrahigh vacuum chamber (UHV), and analyzed by the in situ SE. Evidence for desorption of the H-terminated Si surface layer, after being heated to about 550 C in the UHV chamber, is presented and discussed. This is the first use of an ex situ and in situ real-time, nondestructive technique capable of showing state of passivation, the rate of reoxidation, and the surface roughness of the H-terminated Si surfaces.

  13. Spectroscopic ellipsometry studies of HF treated Si (100) surfaces

    NASA Astrophysics Data System (ADS)

    Yao, Huade; Woollam, John A.; Alterovitz, Samuel A.

    1993-08-01

    Both ex situ and in situ spectroscopic ellipsometry (SE) measurements were employed to investigate the effects of HF cleaning on Si surfaces. The hydrogen-terminated (H-terminated) Si surface was modeled as an equivalent dielectric layer, and monitored in real time by SE measurements. The SE analyses indicate that after a 20-s 9:1 HF dip without rinse, the Si(100) surface was passivated by the hydrogen termination and remained chemically stable. Roughness of the HF-etched bare Si(100) surface was observed, in an ultrahigh vacuum (UHV) chamber, and analyzed by the in situ SE. Evidence for desorption of the H-terminated Si surface-layer, after being heated to approximately 550 C in the UHV chamber, is presented and discussed. This is the first use of an ex situ and in situ real-time, nondestructive technique capable of showing state of passivation, the rate of reoxidation, and the surface roughness of the H-terminated Si surfaces.

  14. Spectroscopic ellipsometry studies of HF treated Si (100) surfaces

    NASA Astrophysics Data System (ADS)

    Yao, Huade; Woollam, John A.; Alterovitz, Samuel A.

    1993-06-01

    Both ex situ and in situ spectroscopic ellipsometry (SE) measurements were employed to investigate the effect of HF cleaning on Si surfaces. The hydrogen-terminated (H-terminated) Si surface was modeled as an equivalent dielectric layer, and monitored in real time by SE measurements. The SE analyses indicate that, after a 20-sec 9:1 HF dip without rinse, the Si (100) surface was passivated by the hydrogen termination and remained chemically stable. Roughness of the HF-etched bare Si (100) surface was observed, in an ultrahigh vacuum chamber (UHV), and analyzed by the in situ SE. Evidence for desorption of the H-terminated Si surface layer, after being heated to about 550 C in the UHV chamber, is presented and discussed. This is the first use of an ex situ and in situ real-time, nondestructive technique capable of showing state of passivation, the rate of reoxidation, and the surface roughness of the H-terminated Si surfaces.

  15. Studies of Two Massive Eclipsing Double-lined Spectroscopic Binaries

    NASA Astrophysics Data System (ADS)

    Williams, Stephen J.; Gies, D. R.; Hillwig, T. C.; McSwain, M. V.; Huang, W.

    2013-06-01

    As part of an ongoing investigation into the spectroscopic variability of massive stars, we present preliminary results for two double-lined eclipsing binary systems, HD 130146 (VZ Cen) and LS 3052 (V 1176 Cen). In our analysis we used archival Hipparcos photometry for HD 103146 and All Sky Automated Survey V-band photometry for LS 3052. All spectra were obtained from the Cerro Tololo Inter-American Observatory 1.5-m telescope. The systems were analyzed using the Eclipsing Light Curve code (ELC; Orosz & Hauschildt 2000). A combined analysis of these data yields masses, radii, effective temperatures, gravities, and estimates for the ages and distances of each system. HD 103146 is a 4.9 day binary with a slightly evolved primary (T_{eff} 28000 K and log g 3.75) while the secondary nearly fills its Roche lobe. LS 3052 has an eccentric orbit with a period of 31 days and contains both an evolved primary and secondary. Preliminary solutions indicate the primary's mass to be 33 Mo with a 21 Mo secondary.

  16. Microstructural studies of AgNbO{sub 3} ceramic by using complex impedance spectroscopy

    SciTech Connect

    Gangaprasad, K.; Rao, T. Durga; Niranjan, Manish K.; Asthana, Saket

    2015-06-24

    Lead-free piezoelectric silver niobate ceramic was synthesized by conventional solid state route. Room temperature X-ray diffraction pattern revealed that the sample crystallizes in single phase orthorhombic perovskite structure. Scanning electron micrographs of AgNbO{sub 3} ceramic showed that the average grain size is in the range 2–3 µm. The electrical properties were investigated by using impedance spectroscopy. Appearance of single semicircular arc in the Nyquist plot indicated the presence of grain contribution in the sample. Single RC parallel circuit model was employed to extract bulk capacitance (C{sub b}), resistance (R{sub b}) and electrical conductivity (σ{sub b}). The activation energy calculated from impedance and modulus data indicate that same types of charge carriers (oxygen vacancy movements) are responsible for conduction and relaxation.

  17. Experimental Study of the Impedance Characteristics of the Plasma Absorption Probe

    NASA Astrophysics Data System (ADS)

    Yamazawa, Yohei

    2011-10-01

    The plasma absorption probe (PAP) is a diagnostic which permits the determination of the spatially resolved electron density in a plasma. The simple structure of the probe allows us a robust measurement; however, the mechanism of the absorption is complicated and several papers report that there is still some uncertainty. Basically, the PAP detects the plasma density by determining the absorption peak frequency in the frequency characteristics of the reflection coefficient. We have shown, by an electromagnetic field simulation (GT3-0003, GEC2009) that the frequency characteristics of the PAP impedance reflect the plasma resonance more directly than the frequency characteristics of the reflection coefficient. This time, we will report the experimental observation of the resonance in the frequency characteristics of impedance.

  18. Acoustic impedance studies in Triassic reservoirs in the Netherlands - application to development and exploration

    SciTech Connect

    Griffiths, M.; Ford, J.

    1995-08-01

    Simple and cost effective seismic forward modelling techniques have been used in conjunction with petrophysical and geological data to provide an integrated approach to understanding the seismic response of Triassic gas reservoirs onshore and offshore Netherlands. Analysis shows that for the Volpriehausen Sandstone in the offshore sector a relationship exists between reservoir acoustic impedance and porosity such that an increase in porosity leads to a decrease in acoustic impedance. Data can be sub-divided on the basis of fluid fill and cementation with trends for both gas and water cases. Regression analysis has defined the optimum relationship for each fluid case and these relationships have been used to predict the acoustic impedance profiles for a variety of reservoir scenarios. Modelling shows that the highest seismic amplitudes and the greatest relative amplitude variation with fluid fill are related to high porosity reservoir. In the onshore sector, analysis for the Roet Sandstone has shown that even small scale variations in reservoir properties can be recorded within the detail of the seismic response. Results from seismic forward modelling compare with amplitude variations observed in real data and suggest that, within the limitations of the dataset and methodology, the technique can be used to predict reservoir attributes from the seismic response. So far, the technique has been sucessfully applied to both exploration and field development projects.

  19. Study on electromechanical impedance characteristics of part of structures made of CFRP

    NASA Astrophysics Data System (ADS)

    Malinowski, Paweł H.; Wandowski, Tomasz; Ostachowicz, Wiesław M.

    2016-04-01

    Carbon Fibre Reinforced Polymers (CFRP) are more and more used in many branches of industry. Researchers are developing numerous techniques of non-destructive assessment of the structures made out of CFRP such as guided waves, ultrasonics, laser induced fluorescence and others. In this research we focus on electromechanical impedance (EMI) technique. In this technique a piezoelectric sensor is either surface mounted or embedded into investigated host structure. The electrical quantities of the sensor are measured for wide frequency range. Due to piezoelectric effect the electrical response of the sensor is related to mechanical response of the structure to which the sensors is bonded to. In the reported research impedance spectra in the vicinity of the transducer thickness mode were investigated as well as the lower frequency range. The spectra that were analysed were gathered from samples with surface treatment such as thermal degradation and samples adhesively bonded with film adhesive with symmetric and unsymmetric bond. Moreover, the samples with modified adhesive bonds were investigated. These spectra for different cases were compared with reference measurement results gathered from pristine samples. Numerical indexes for comparison of the EMI characteristics were proposed. The comparison of the indexes was also conducted. In the experimental part of the research the piezoelectric transducer was mounted at the sample surface. Measurements were conducted using HIOKI Impedance Analyzer IM3570.

  20. RF impedance studies of a beam chamber and longitudinally slot-coupled vacuum pumping antechamber

    SciTech Connect

    Kustom, R.L.; Nicholls, G.L.; Kramer, S.L.; Khoe, T.K.; Cook, J.M.

    1987-01-01

    The storage ring vacuum chamber of the proposed 7-GeV synchrotron light source at Argonne National Laboratory is planned to have a semi-elliptical beam chamber, with a longitudinal slot coupled to an antechamber containing NEG pumping strips. Concern over the RF impedance of this complex chamber has stimulated the need to understand the limitations it will have on the beam intensity, the RF acceleration system and on the beam lifetime. Calculations using numerical EM field programs have estimated the waveguide modes of this chamber and the impedance and loss parameter for the expected 1 to 2 cm beam bunch length. The loss parameter is shown to differ little from an elliptical beam chamber without the slot and antechamber. An experimental program has begun to verify the estimates of the impedance for these complex vacuum chamber components using laboratory methods. Preliminary results are presented for the measured loss parameter for a short length of beam vacuum chamber and for other components. These results are compared with their calculated values.

  1. Raman spectroscopic study of the Chromobacterium violaceum pigment violacein using multiwavelength excitation and DFT calculations.

    PubMed

    Jehlička, Jan; Edwards, Howell G M; Němec, Ivan; Oren, Aharon

    2015-12-01

    Violacein is a bisindole pigment occurring as a biosynthetic product of Chromobacterium violaceum and Janthinobacterium lividum. It has some structural similarities to the cyanobacterial UV-protective pigment scytonemin, which has been the subject of comprehensive spectroscopic and structural studies. A detailed experimental Raman spectroscopic study with visible and near-infrared excitation of violacein produced by C. violaceum has been undertaken and supported using theoretical DFT calculations. Raman spectra with 514 and 785 nm excitation of cultivated cells as well as extracts and Gaussian (B3LYP/6-311++G(d,p)) calculations with proposed molecular vibrational assignments are reported here. PMID:26151435

  2. An Experimental Study on the Effect of Temperature on Piezoelectric Sensors for Impedance-Based Structural Health Monitoring

    PubMed Central

    Baptista, Fabricio G.; Budoya, Danilo E.; de Almeida, Vinicius A. D.; Ulson, Jose Alfredo C.

    2014-01-01

    The electromechanical impedance (EMI) technique is considered to be one of the most promising methods for developing structural health monitoring (SHM) systems. This technique is simple to implement and uses small and inexpensive piezoelectric sensors. However, practical problems have hindered its application to real-world structures, and temperature effects have been cited in the literature as critical problems. In this paper, we present an experimental study of the effect of temperature on the electrical impedance of the piezoelectric sensors used in the EMI technique. We used 5H PZT (lead zirconate titanate) ceramic sensors, which are commonly used in the EMI technique. The experimental results showed that the temperature effects were strongly frequency-dependent, which may motivate future research in the SHM field. PMID:24434878

  3. Establishment of equivalent circuits from electrochemical impedance spectroscopy study of corrosion inhibition of steel by pyrazine in sulphuric acidic solution

    NASA Astrophysics Data System (ADS)

    Kissi, M.; Bouklah, M.; Hammouti, B.; Benkaddour, M.

    2006-04-01

    This paper describes the use of the electrochemical impedance spectroscopy technique (EIS) in order to study the corrosion inhibition process of steel in 0.5 M H 2SO 4 solution at the open circuit potential (OCP). Diethyl pyrazine-2,3-dicarboxylate (Prz) as a non-ionic surfactant (NS) inhibitor has been examined. The Nyquist diagrams consisted of a capacitive semicircle at high frequencies followed by a well-defined inductive loop at low frequency values. The impedance measurements were interpreted according to suitable equivalent circuits. The results obtained showed that the Prz is a good inhibitor. The inhibition efficiency increases with an increase in the surfactant concentration to attain 80% at the 5 × 10 -3M. Prz is adsorbed on the steel surface according to a Langmuir isotherm adsorption model.

  4. Spectroscopic studies of the small-amplitude Cepheid SU Cas

    NASA Astrophysics Data System (ADS)

    Usenko, I. A.; Klochkova, V. G.; Tavolzhanskaya, N. S.

    2013-09-01

    A new set of 16 high-resolution spectra for the small-amplitude Cepheid SU Cas obtained in 2007-2009 has allowed us to determine its atmospheric parameters ( T eff = 6345 ± 30 K, log g = 2.40, V t = 3.25 km s-1) and to measure its radial velocities. The latter were added to the general list of radial velocities (375 estimates) obtained in the last 90 years. Using a frequency analysis, we have refined the pulsation and orbital periods of the Cepheid. Apart from the well-known fundamental pulsation period [Figure not available: see fulltext.], we have detected a possible secondary period of [Figure not available: see fulltext.]. Their ratio of 0.96 suggests the existence of nonradial pulsations in the Cepheid's atmosphere. Based on photoelectric photometry in the last 60 years, we have shown that the effective temperature undergoes cyclic secular changes of ±200 K with an unknown period. The mean effective temperature T eff = 6395 ± 52 K estimated from photometric data agrees well with our estimate from spectroscopic data. The variations of the mean color index, effective temperature, and γ-velocity (in 90 years of observations) point to a possible orbital motion of the well-known hot companion with the most probable periods of [Figure not available: see fulltext.], [Figure not available: see fulltext.], and [Figure not available: see fulltext.]. The elemental abundances in the atmosphere of SU Cas confirm the conclusion that this Cepheid is a typical yellow supergiant after the first dredge-up. Our T eff estimate gives a radius of 32 R ⊙ and a distance of 455 pc for it, which is inconsistent with its membership in the open cluster Alessi 95. The question about the pulsation mode of SU Cas still remains open.

  5. Impedance magnetocardiogram.

    PubMed

    Kandori, A; Miyashita, T; Suzuki, D; Yokosawa, K; Tsukada, K

    2001-02-01

    We have developed an impedance magnetocardiogram (IMCG) system to detect the change of magnetic field corresponding to changes in blood volume in the heart. A low magnetic field from the electrical activity of the human heart--the so-called magnetocardiogram (MCG)--can be simultaneously detected by using this system. Because the mechanical and electrical functions in the heart can be monitored by non-invasive and non-contact measurements, it is easy to observe the cardiovascular functions from an accurate sensor position. This system uses a technique to demodulate induced current in a subject. A flux-locked circuit of a superconducting quantum interference device has a wide frequency range (above 1 MHz) because a constant current (40 kHz) is fed through the subject. It is shown for the first time that the system could measure IMCG signals at the same time as MCG signals. PMID:11229740

  6. Impedance analysis of forging process and strategy study on compliance for forging manipulator

    NASA Astrophysics Data System (ADS)

    Zhang, Pu; Yao, Zhenqiang; Du, Zhengchun

    2013-07-01

    In the field of heavy forging, there are numerous researches on deformation rule in forging process by FEM simulation, however, not many scholars take the equipment constraint and the mutual reaction load between the forging manipulator clamp and the forging blank into account, which will impact on safety of manipulator body and quality of forging blank. This paper presents an impedance model to describe the load and formulates compliance strategies correspondingly to reduce the mutual reaction load for forging manipulator. Firstly, an FEM model of forging process is built. Meanwhile, the clamp of forging manipulator is added to the model as movement constraint and interaction part between the manipulator and the forming process. Secondly, a typical forging process is simulated by changing the movement constraint, and then an impedance model is established to describe the relationship between the load and movement constraint. Finally, two kinds of compliance strategies are formulated according to the impedance model, one is called free compliance, and the other is initiative/passive compliance. The simulation results show that compliance strategies reduce the load amounting to 5 000 kN in z direction between the manipulator clamp and the forging blank obviously, which may lead to serious accidents, such as the capsizing of forging manipulator, the fracture of manipulator clamp, and so on. The proposed research simulates the more real forging process, gets the initiative/passive compliance strategy which is more simple and suitable to the real producing and better for forming a forging process planning and control system in the modern production, and improves the quality and efficiency of heavy forging.

  7. Models of Longitudinal Space-Charge Impedance for the Study of theMicrobunching Instability

    SciTech Connect

    Venturini, Marco

    2008-03-10

    A 1D model of space-charge impedance, assuming atransversely uniform beam with circular cross-section, has been proposedand is being extensively used in the modelling of the microbunchinginstability of relevance for the beam delivery systems of x-ray FELs. Inthis paper we investigate the limitation of the model when applied tostudying the effect of shot noise--one of the sources of themicrobunching instability. We make comparison witha fully 3D calculationand identify the upper end of the frequency spectrum for applicability ofthe 1D model. Relaxation of the assumptions regarding axis-symmetry anduniformity of the transverse density is also reviewed.

  8. Pump probe based Raman spectroscopic studies of PTFE under laser driven shock compression

    NASA Astrophysics Data System (ADS)

    Rastogi, Vinay; Rao, Usha; Chaurasia, S.; Mishra, A. K.; Poswal, H. K.; Deo, M. N.; Sharma, S. M.

    2016-05-01

    High pressure spontaneous Raman spectroscopic studies of poly tetra fluro ethylene (PTFE) have been carried out under laser driven shock compression in confinement geometry target. The Raman modes under shock compression as a function of pressure were measured and compared with the corresponding Raman modes in static pressure experiments. Our results indicate that PTFE undergoes transition to phase III across this pressure.

  9. Structural, dielectric and impedance studies of polycrystalline La0.6Gd0.2Ca0.2MnO3

    NASA Astrophysics Data System (ADS)

    Nandan K., R.; Rubankumar, A.; Kalainathan, S.

    2016-05-01

    Polycrystalline materials of Gd doped La1-xCaxMnO3 were prepared by Sol-Gel technique using citric acid as a chelating agent at 9000 C. The single phase formation of Gd doped LCMO were determined by Powder XRD, dielectric studies and impedance studies is investigated. The existence of dielectric relaxation and release of space charges were observed in the dielectric constant and real part of impedance plots respectively. The shift in the peaks for imaginary part of impedance revealed the existence of relaxation process due to oxygen vacancy. The existence of single semicircle in the cole-cole plot confirms the dielectric relaxation in the prepared sample.

  10. Study of metal corrosion using ac impedance techniques in the STS launch environment

    NASA Technical Reports Server (NTRS)

    Calle, Luz M.

    1989-01-01

    AC impedance measurements were performed to investigate the corrosion resistance of 19 alloys under conditions similar to the STS launch environment. The alloys were: Zirconium 702, Hastelloy C-22, Inconel 625, Hastelloy C-276, Hastelloy C-4, Inconel 600, 7Mo + N, Ferralium 255, Inco Alloy G-3, 20Cb-3, SS 904L, Inconel 825, SS 304LN, SS 316L, SS 317L, ES 2205, SS 304L, Hastelloy B-2, and Monel 400. AC impedance data were gathered for each alloy after one hour immersion time in each of the following three electrolyte solutions: 3.55 percent NaCl, 3.55 percent NaCl-0.1N HCl, and 3.55 percent NaCl-1.0N HCl. The data were analyzed qualitatively using the Nyquist plot and quantitatively using the Bode plot. Polarization resistance, Rp, values were obtained using the Bode plot. Zirconium 702 was the most corrosion resistant alloy in the three electrolytes. The ordering of the other alloys according the their resistance to corrosion varied as the concentration of hydrochloric acid in the electrolyte increased. The corrosion resistance of Zirconium 702 and Ferralium 255 increased as the concentration of hydrochloric acid in the electrolyte increased. The corrosion resistance of the other 17 alloys decreased as the concentration of the hyrdochloric acid in the electrolyte increased.

  11. Hydrogen-terminated detonation nanodiamond: Impedance spectroscopy and thermal stability studies

    NASA Astrophysics Data System (ADS)

    Su, Shi; Li, Jiangling; Kundrát, Vojtěch; Abbot, Andrew M.; Ye, Haitao

    2013-01-01

    In this paper, we investigated the effect of hydrogen termination on the electrical properties and impedance spectra of detonation nanodiamond. The impedance spectra revealed that the hydrogen-termination process increases the electrical conductivity by four orders of magnitude at room temperature. An equivalent circuit has been proposed to correlate with the conduction mechanism. Arrhenius plot showed that there were two different activation energy levels located at 0.089 eV and 0.63 eV between 50 °C and 400 °C. The possible physical mechanism corresponding to these activation energy levels has been discussed. Hydrogen-terminated detonation nanodiamond has been further annealed at different temperatures prior to FTIR and XPS measurements in order to understand their thermal stability. The results demonstrated that the surface oxidization occurred between 100 °C and 150 °C. However, the C-H bonds could partially survive when the temperature reaches 400 °C in air.

  12. A Comparison Study of Normal-Incidence Acoustic Impedance Measurements of a Perforate Liner

    NASA Technical Reports Server (NTRS)

    Schultz, Todd; Liu, Fei; Cattafesta, Louis; Sheplak, Mark; Jones, Michael

    2009-01-01

    The eduction of the acoustic impedance for liner configurations is fundamental to the reduction of noise from modern jet engines. Ultimately, this property must be measured accurately for use in analytical and numerical propagation models of aircraft engine noise. Thus any standardized measurement techniques must be validated by providing reliable and consistent results for different facilities and sample sizes. This paper compares normal-incidence acoustic impedance measurements using the two-microphone method of ten nominally identical individual liner samples from two facilities, namely 50.8 mm and 25.4 mm square waveguides at NASA Langley Research Center and the University of Florida, respectively. The liner chosen for this investigation is a simple single-degree-of-freedom perforate liner with resonance and anti-resonance frequencies near 1.1 kHz and 2.2 kHz, respectively. The results show that the ten measurements have the most variation around the anti-resonance frequency, where statistically significant differences exist between the averaged results from the two facilities. However, the sample-to-sample variation is comparable in magnitude to the predicted cross-sectional area-dependent cavity dissipation differences between facilities, providing evidence that the size of the present samples does not significantly influence the results away from anti-resonance.

  13. An impedance study of two types of stainless steel in Ringer physiological solution containing complexing agents.

    PubMed

    Slemnik, Mojca; Milosev, Ingrid

    2006-10-01

    The effect of complexing agents EDTA and citric acid on the electrochemical behaviour of AISI 304 and orthopaedic stainless steels in Ringer physiological solution was investigated by potentiodynamic polarization method and electrochemical impedance spectroscopy (EIS). The content of Mo has a pronounced effect on the corrosion resistance, as evident by the broader passive range of the orthopaedic stainless steel containing Mo. The addition of complexing agents induces significant changes in polarization and impedance characteristics, i.e., the shift of corrosion and breakdown potentials in a more negative direction, an increase in current density, and a significant decrease in charge transfer resistance. The results were interpreted by the formation of soluble complexes of metal ions with chelating agents, especially EDTA, which suppressed the formation of the outer Fe(III) layer of the passive film. The impact of complexing agent on the electrochemical parameters was found to be related to its concentration in electrolyte and the stability constant of the complex formed with the related metal ion. PMID:16977388

  14. Electrical impedance tomography to evaluate air distribution prior to extubation in very-low-birth-weight infants: a feasibility study

    PubMed Central

    de Souza Rossi, Felipe; Yagui, Ana Cristina Zanon; Haddad, Luciana Branco; Deutsch, Alice D'Agostini; Rebello, Celso Moura

    2013-01-01

    OBJECTIVES: Nasal continuous positive airway pressure is used as a standard of care after extubation in very-low-birth-weight infants. A pressure of 5 cmH2O is usually applied regardless of individual differences in lung compliance. Current methods for evaluation of lung compliance and air distribution in the lungs are thus imprecise for preterm infants. This study used electrical impedance tomography to determine the feasibility of evaluating the positive end-expiratory pressure level associated with a more homogeneous air distribution within the lungs before extubation. METHODS: Ventilation homogeneity was defined by electrical impedance tomography as the ratio of ventilation between dependent and non-dependent lung areas. The best ventilation homogeneity was achieved when this ratio was equal to 1. Just before extubation, decremental expiratory pressure levels were applied (8, 7, 6 and 5 cmH20; 3 minutes each step), and the pressure that determined the best ventilation homogeneity was defined as the best positive end-expiratory pressure. RESULTS: The best positive end-expiratory pressure value was 6.3±1.1 cmH20, and the mean continuous positive airway pressure applied after extubation was 5.2±0.4 cmH20 (p = 0.002). The extubation failure rate was 21.4%. X-Ray and blood gases after extubation were also checked. CONCLUSION: This study demonstrates that electrical impedance tomography can be safely and successfully used in patients ready for extubation to suggest the best ventilation homogeneity, which is influenced by the level of expiratory pressure applied. In this feasibility study, the best lung compliance was found with pressure levels higher than the continuous positive airway pressure levels that are usually applied for routine extubation. PMID:23644854

  15. Insight into lattice thermal impedance via equilibrium molecular dynamics: case study on Al

    NASA Astrophysics Data System (ADS)

    Evteev, Alexander V.; Levchenko, Elena V.; Momenzadeh, Leila; Belova, Irina V.; Murch, Graeme E.

    2016-02-01

    Using results of equilibrium molecular dynamics simulation in conjunction with the Green-Kubo formalism, we present a general treatment of thermal impedance of a crystal lattice with a monatomic unit cell. The treatment is based on an analytical expression for the heat current autocorrelation function which reveals, in a monatomic lattice, an energy gap between the origin of the phonon states and the beginning of the energy spectrum of the so-called acoustic short-range phonon modes. Although, we consider here the f.c.c. Al model as a case example, the analytical expression is shown to be consistent for different models of elemental f.c.c. crystals over a wide temperature range. Furthermore, we predict a frequency 'window' where the thermal waves can be generated in a monatomic lattice by an external periodic temperature perturbation.

  16. SURFACE SEGREGATION STUDIES OF SOFC CATHODES: COMBINING SOFT X-RAYS AND ELECTROCHEMICAL IMPEDENCE SPECTROSCOPY

    SciTech Connect

    Miara, Lincoln J.; Piper, L.F.J.; Davis, Jacob N.; Saraf, Laxmikant V.; Kaspar, Tiffany C.; Basu, Soumendra; Smith, K. E.; Pal, Uday B.; Gopalan, Srikanth

    2010-12-01

    A system to grow heteroepitaxial thin-films of solid oxide fuel cell (SOFC) cathodes on single crystal substrates was developed. The cathode composition investigated was 20% strontium-doped lanthanum manganite (LSM) grown by pulsed laser deposition (PLD) on single crystal (111) yttria-stabilized zirconia (YSZ) substrates. By combining electrochemical impedance spectroscopy (EIS) with x-ray photoemission spectroscopy (XPS) and x-ray absorption spectroscopy XAS measurements, we conclude that electrically driven cation migration away from the two-phase gas-cathode interface results in improved electrochemical performance. Our results provide support to the premise that the removal of surface passivating phases containing Sr2+ and Mn2+, which readily form at elevated temperatures even in O2 atmospheric pressures, is responsible for the improved cathodic performance upon application of a bias.

  17. Impedance and self-discharge mechanism studies of nickel metal hydride batteries for energy storage applications

    NASA Astrophysics Data System (ADS)

    Zhu, Wenhua; Zhu, Ying; Tatarchuk, Bruce

    2013-04-01

    Nickel metal hydride battery packs have been found wide applications in the HEVs (hybrid electric vehicles) through the on-board rapid energy conservation and efficient storage to decrease the fossil fuel consumption rate and reduce CO2 emissions as well as other harmful exhaust gases. In comparison to the conventional Ni-Cd battery, the Ni-MH battery exhibits a relatively higher self-discharge rate. In general, there are quite a few factors that speed up the self-discharge of the electrodes in the sealed nickel metal hydride batteries. This disadvantage eventually reduces the overall efficiency of the energy conversion and storage system. In this work, ac impedance data were collected from the nickel metal hydride batteries. The self-discharge mechanism and battery capacity degradation were analyzed and discussed for further performance improvement.

  18. Vibrational spectroscopic studies to acquire a quality control method of Eucalyptus essential oils.

    PubMed

    Baranska, M; Schulz, H; Reitzenstein, S; Uhlemann, U; Strehle, M A; Krüger, H; Quilitzsch, R; Foley, W; Popp, J

    2005-08-01

    This article presents a novel and original approach to analyze in situ the main components of Eucalyptus oil by means of Raman spectroscopy. The obtained two-dimensional Raman maps demonstrate a unique possibility to study the essential oil distribution in the intact plant tissue. Additionally, Fourier Transform (FT)-Raman and attenuated total reflection (ATR)-IR spectra of essential oils isolated from several Eucalyptus species by hydrodistillation are presented. Density Functional Theory (DFT) calculations were performed in order to interpret the spectra of the essential oils of the Eucalyptus species. It is shown that the main components of the essential oils can be recognized by both vibrational spectroscopic techniques using the spectral information of the pure terpenoids. Spectroscopic analysis is based on the key bands of the individual volatile substances and therefore allows one to discriminate different essential oil profiles of several Eucalyptus species. It has been found that the presented spectroscopic data correlate very well with those obtained by gas chromatography (GC) analysis. All these investigations are helpful tools to generate a fast and easy method to control the quality of the essential oils with vibrational spectroscopic techniques in combination with DFT calculations. PMID:15856523

  19. High-impedance wire grid method to study spatiotemporal behavior of hot electron clump generated in a plasma.

    PubMed

    Terasaka, K; Yoshimura, S; Kato, Y; Furuta, K; Aramaki, M; Morisaki, T; Tanaka, M Y

    2014-11-01

    High-impedance Wire Grid (HIWG) detector has been developed to study spatiotemporal behavior of a hot electron clump generated in an electron cyclotron resonance (ECR) plasma. By measuring the floating potentials of the wire electrodes, and generating structure matrix made of geometrical means of the floating potentials, the HIWG detector reconstructs the spatial distribution of high-temperature electron clump at an arbitrary instant of time. Time slices of the spike event in floating potential revealed the growth and decay process of a hot spot occurs in an ECR plasma. PMID:25430112

  20. High-impedance wire grid method to study spatiotemporal behavior of hot electron clump generated in a plasma

    SciTech Connect

    Terasaka, K. Kato, Y.; Tanaka, M. Y.; Yoshimura, S.; Morisaki, T.; Furuta, K.; Aramaki, M.

    2014-11-15

    High-impedance Wire Grid (HIWG) detector has been developed to study spatiotemporal behavior of a hot electron clump generated in an electron cyclotron resonance (ECR) plasma. By measuring the floating potentials of the wire electrodes, and generating structure matrix made of geometrical means of the floating potentials, the HIWG detector reconstructs the spatial distribution of high-temperature electron clump at an arbitrary instant of time. Time slices of the spike event in floating potential revealed the growth and decay process of a hot spot occurs in an ECR plasma.

  1. How specific Raman spectroscopic models are: a comparative study between different cancers

    NASA Astrophysics Data System (ADS)

    Singh, S. P.; Kumar, K. Kalyan; Chowdary, M. V. P.; Maheedhar, K.; Krishna, C. Murali

    2010-02-01

    Optical spectroscopic methods are being contemplated as adjunct/ alternative to existing 'Gold standard' of cancer diagnosis, histopathological examination. Several groups are actively pursuing diagnostic applications of Ramanspectroscopy in cancers. We have developed Raman spectroscopic models for diagnosis of breast, oral, stomach, colon and larynx cancers. So far, specificity and applicability of spectral- models has been limited to particular tissue origin. In this study we have evaluated explicitly of spectroscopic-models by analyzing spectra from already developed spectralmodels representing normal and malignant tissues of breast (46), cervix (52), colon (25), larynx (53), and oral (47). Spectral data was analyzed by Principal Component Analysis (PCA) using scores of factor, Mahalanobis distance and Spectral residuals as discriminating parameters. Multiparametric limit test approach was also explored. The preliminary unsupervised PCA of pooled data indicates that normal tissue types were always exclusive from their malignant counterparts. But when we consider tissue of different origin, large overlap among clusters was found. Supervised analysis by Mahalanobis distance and spectral residuals gave similar results. The 'limit test' approach where classification is based on match / mis-match of the given spectrum against all the available spectra has revealed that spectral models are very exclusive and specific. For example breast normal spectral model show matches only with breast normal spectra and mismatch to rest of the spectra. Same pattern was seen for most of spectral models. Therefore, results of the study indicate the exclusiveness and efficacy of Raman spectroscopic-models. Prospectively, these findings might open new application of Raman spectroscopic models in identifying a tumor as primary or metastatic.

  2. Spectroscopic and dynamical studies of highly energized small polyatomic molecules

    SciTech Connect

    Field, R.W.; Silbey, R.J.

    1990-01-01

    The formyl radical and the acetylene molecule were chosen for these studies. The visible and fluorescence spectra of the formyl radical were recorded, and the spectral results are used as a basis to explain the electronic structure. Optical-optical double resonance studies of acetylene were recorded, and the spectral results are interpreted. The results of Zeeman and Stark anticrossing and quantum beat studies of acetylene are reported, and they provide an unusually detailed view of both Intersystem Crossing and Internal Conversion in small polyatomic molecules. 22 references are cited as resulting from Department of Energy sponsorship of this project.

  3. Spectroscopic study of the humification process during sewage sludge treatment

    NASA Astrophysics Data System (ADS)

    Pajączkowska, J.; Sułkowska, A.; Sułkowski, W. W.; Jędrzejczyk, M.

    2003-06-01

    The aim of this work was to study the free radical transition of organic materials during the sewage treatment process. Investigations of sludge from biologic-mechanical sewage treatment plant in Sosnowiec Zagórze were carried out. The course of the humification processes during sewage treatment was studied by electron paramagnetic resonance (EPR) technique. The concentration of free radicals at each process stage and the value g were determined. Sludge samples and extracted fractions of humic acids were examined. Humic acids were extracted from sludge by means of conventional methods elaborated by Stevenson. For study of humic acids structures, besides EPR, the UV-Vis and IR spectroscopy were used.

  4. Laser-induced breakdown spectroscopic study of ammonium nitrate plasma

    SciTech Connect

    Hanif, M.; Salik, M.; Baig, M. A.

    2013-12-15

    We present the optical emission studies of the ammonium nitrate plasma produced by the fundamental (1064 nm) and second (532 nm) harmonics of a Q-switched Nd: YAG laser. The target material was placed in front of the laser beam in an open atmospheric air. The spectrum reveals numerous transitions of neutral nitrogen. We have studied the spatial behavior of the plasma temperature (T{sub e}) and electron number density (N{sub e}) determined using the Boltzmann plot method and Stark broadened line profiles, respectively. Besides, we have studied the variation of the plasma parameters as a function of the laser irradiance.

  5. SPECTROSCOPIC STUDIES OF MATERIALS FOR ELECTROCHEMICAL ENERGY STORAGE

    SciTech Connect

    Greenbaum, Steven G.

    2014-03-01

    Several battery materials research projects were undertaken, suing NMR spectroscopy as a primary analytical tool. These include transport proerties of liquid and solid electrolytes and structural studies of Li ion electrodes.

  6. SPECTROSCOPIC STUDY OF SORPTION OF NITROGEN HETEROCYCLIC COMPOUNDS ON PHYLLOSILICATES

    EPA Science Inventory

    The present study focused on understanding the sorption characteristics of acridine (AcN)and acridine-9-carboxylic acid (AcNCOOH), two typical nitrogen heterocyclic compounds (NHCs), on well-characterized phyllosilicates (hectorite, saponite, and muscovite). Results presented in...

  7. Electromagnetic scattering by impedance structures

    NASA Technical Reports Server (NTRS)

    Balanis, Constantine A.; Griesser, Timothy

    1987-01-01

    The scattering of electromagnetic waves from impedance structures is investigated, and current work on antenna pattern calculation is presented. A general algorithm for determining radiation patterns from antennas mounted near or on polygonal plates is presented. These plates are assumed to be of a material which satisfies the Leontovich (or surface impedance) boundary condition. Calculated patterns including reflection and diffraction terms are presented for numerious geometries, and refinements are included for antennas mounted directly on impedance surfaces. For the case of a monopole mounted on a surface impedance ground plane, computed patterns are compared with experimental measurements. This work in antenna pattern prediction forms the basis of understanding of the complex scattering mechanisms from impedance surfaces. It provides the foundation for the analysis of backscattering patterns which, in general, are more problematic than calculation of antenna patterns. Further proposed study of related topics, including surface waves, corner diffractions, and multiple diffractions, is outlined.

  8. Sum frequency generation vibrational spectroscopic studies on buried heterogeneous biointerfaces.

    PubMed

    Zhang, Chi; Jasensky, Joshua; Leng, Chuan; Del Grosso, Chelsey; Smith, Gary D; Wilker, Jonathan J; Chen, Zhan

    2014-05-01

    A sum frequency generation (SFG) vibrational micro-spectroscopy system was developed to examine buried heterogeneous biointerfaces. A compact optical microscope was constructed with total-internal reflection (TIR) SFG geometry to monitor the tightly focused SFG laser spots on interfaces, providing the capability of selectively probing different regions on heterogeneous biointerfaces. The TIR configuration ensures and enhances the SFG signal generated only from the sample/substrate interfacial area. As an example for possible applications in biointerfaces studies, the system was used to probe and compare buried interfacial structures of different biological samples attached to underwater surfaces. We studied the interface of a single mouse oocyte on a silica prism to demonstrate the feasibility of tracing and studying a single live cell and substrate interface using SFG. We also examined the interface between a marine mussel adhesive plaque and a CaF2 substrate, showing the removal of interface-bonded water molecules. This work also paves the way for future integration of other microscopic techniques such as TIR-fluorescence microscopy or nonlinear optical imaging with SFG spectroscopy for multimodal surface or interface studies. PMID:24784085

  9. Photoemission Spectroscopic Study of Cesium Telluride Thin Film Photocathode

    SciTech Connect

    Sugiyama, Harue; Ogawa, Koji; Azuma, Junpei; Takahashi, Kazutoshi; Kamada, Masao

    2009-08-04

    The photoemission spectroscopy using synchrotron radiation has been carried out to study the high quantum efficiency and long working lifetime of cesium telluride (Cs{sub x}Te{sub y}) thin film photocathode. The electron affinity derived from the observed energy-distribution curves provides an important hint for long persistency of the photocathode.

  10. LEAD SORPTION ON RUTHENIUM OXIDE: A MACROSCOPIC AND SPECTROSCOPIC STUDY

    EPA Science Inventory

    Metal oxide phases play an important role in governing the sorption and desorption mechanisms of metals in water, soils, and sediments. Many researchers have examined the efficiency of Pb sorption on Mn, Fe, Al, Ti, and Si oxide surfaces. Most studies concluded that adsorption ...

  11. Structural, Magnetic and Spectroscopic Studies of Thin Manganite Films

    NASA Astrophysics Data System (ADS)

    Tyson, T. A.

    2003-03-01

    Starting from early experiments [1], evidence has been found for a close coupling of strain and the magnetotransport properties of manganite films. The characteristic feature found is that the metal to insulator transition temperature (TMI) is suppressed in very thin films [2]. In addition, studies show that the magnetic transition temperature (Tc) and TMI decouple in ultrathin films [3]. Systematic magnetization studies reveal that strain induces strong magnetic anisotropy [4]. Theoretical work also points to the sensitivity of Tc to biaxial strain [5]. Most studies have focused on single bulk properties. In order to understand the correlations between strain and the transport and magnetic properties we have examined the structure of films on multiple length scales. The local structure of films have been studies by x-ray absorption spectroscopy. The long -range structure has been studied by high-resolution x-ray diffraction and the microstructure has been studied by AFM measurements. These measurements are correlated with bulk magnetization and transport studies. Insight is gained on the evolution of lattice strain and Jahn-Teller distortions with thickness. Direct evidence is found for the arrest of charge ordering with strain and the existence of strain induced insulating regions of films. The magnetic ordering and transport properties as a function of strain as compared with bandstructure calculations. This work is supported by NSF Career Grant DMR-9733862 and DMR-0209243. Collaborators: Q. Qian, M. Deleon (NJIT), C. Dubourdiu (CNRS), J. Bai (ORNL), W. Prellier, A. Biswas, R. L. Greene (U. Maryland) [1] S. Jin et al., Appl. Phys. Lett. 67, 557 (1995). [2] (a) J. Z. Sun et al. Appl. Phys. Lett. 74, 3017 (1999). (b) F. S. Razi et al., Appl. Phys. Lett 76, 155 (2000) [3] J. Aarts et al., Appl. Phys. Lett. 72, 2975 (1998). (b) R. A. Rao et al., J. Appl. Phys. 85, 4794 (1999). [4] (a) X. W. Wu et al., Phys. Rev. B 61, 501 (2000). (b) J. O'Donnell et al., Appl. Phys

  12. Magnetic resonance and optical spectroscopic studies of carotenoids

    SciTech Connect

    Kispert, L.D.

    1991-05-01

    It is our goal to study the role of a host lattice in the formation of radicals and excited singlet and triplet states that are relevant to photosynthesis. Particular emphasis is being placed on determining what is special about carotenoids that natural photosynthetic systems require them as antennae as well as for protection. We are thus manipulating the host matrix so as to understand the carotenoid function (protection, quenching, energy transfer and antenna) and the structure of carotenoid cations. To characterize their properties, we have carried out EPR, ENDOR, optical, molecular orbital and electrochemical studies of carotenoids and carotenoid cations produced chemically, electrochemically, radiolytically (x-ray irradiated freon matrices) and photolytically (solution photolysis by excimer radiation) as a function of the host matrix. 36 refs.

  13. Spectroscopic studies of laser ablation plumes of artwork materials

    NASA Astrophysics Data System (ADS)

    Oujja, M.; Rebollar, E.; Castillejo, M.

    2003-04-01

    Studies on the plasma plume created during KrF laser (248 nm) ablation of dosimeter tempera samples in vacuum have been carried out to investigate the basic interactions of the laser with paint materials. Time resolved optical emission spectroscopy (OES) was used to measure the translational velocity of electronically excited transients in the plasma plume. Laser-induced fluorescence (LIF) studies using a probe dye laser, allowed to determine the velocities of non-emitting species. The propagation velocities of C 2 in the a 3π u and d 3π g electronic states and of excited atomic species are indicative of a high translational temperature. Differences between the velocities of organic and inorganic species and between emissions from the tempera systems and from the pigments as pellets allow to discuss the participation of photochemical mechanisms in the laser irradiation of the paint systems.

  14. Thiosaccharine disulfide: Synthesis, crystal structure, spectroscopic characterization and theoretical study

    NASA Astrophysics Data System (ADS)

    Ferullo, Ricardo M.; Granados, Alejandro; Lanterna, Anabel; Güida, Jorge A.; Piro, Oscar E.; Castellano, Eduardo E.; Dennehy, Mariana

    2013-01-01

    The title compound, (thiosaccharine disulfide), bis[1,1'dioxide-2,3-dihidro-1,2-benzoisothiazol]disulfide, (tsac)2 has been synthesized and fully characterized by UV-Visible, IR, Raman, 1H and 13C NMR spectroscopy elemental analysis and structural X-ray crystallography. A DFT theoretical study has been performed and good agreement between experimental and theoretical values of structural parameters and vibration frequencies have been achieved.

  15. Spectroscopic and computational study of a new isomer of salinomycin

    NASA Astrophysics Data System (ADS)

    Pankiewicz, Radosław

    2013-09-01

    A new derivative of polyether ionophore salinomycin was obtained as a result of a rearrangement catalysed by sulphuric acid in two-phase medium of water/methylene chloride solution. The new isomer was fully characterized by multinuclear 2D NMR, NOESY and MALDI-TOF. The properties of the new compound were additionally study by semiempirical (PM5) and DFT (B3LYP) methods. A potential mechanism of the rearrangement was also proposed.

  16. Spectroscopic studies of model polar stratospheric cloud films

    NASA Technical Reports Server (NTRS)

    Tolbert, Margaret A.; Koehler, Birgit G.; Middlebrook, Ann M.

    1993-01-01

    Fourier transform infrared (FTIR) spectroscopy has been used to study nitric-acid/ice films representative of type I polar stratospheric clouds (PSCs). These studies reveal that in addition to amorphous nitric acid/ice mixtures, there are three stable stoichiometric hydrates of nitric acid: nitric-acid monohydrate (NAM), dihydrate (NAD), and trihydrate (NAT). We also observe two distinct crystalline forms of the trihydrate, which we denote alpha- and beta-NAT. These two forms appear to differ in their concentration of crystalline defects, but not in their chemical composition. In addition to probing the composition of type I PSCs, we have also used FTIR spectroscopy to study the interaction of HCl with model PSC films. In this work we find that for HCl pressures in the range 10 exp -5 to 10 exp -7 Torr, HCl is taken up by ice at 155 K to form a thin layer of HCl.6H2O. At 193 K, the uptake of HCl by ice was consistent with less than or equal to monolayer coverage. Uptake of HCl by alpha and beta-NAT at 175 K was also consistent with less than or equal to monolayer coverage.

  17. Raman microprobe spectroscopic studies of solid DNA-CTMA films

    NASA Astrophysics Data System (ADS)

    Yaney, Perry P.; Ahmad, Faizan; Grote, James G.

    2008-08-01

    Extensive studies have been carried out on developing the new biopolymer, deoxyribonucleic acid (DNA) derived from salmon, that has been complexed with a surfactant to make it water insoluble for application to bioelectronic and biophotonic devices. One of the key issues associated with the properties and behavior of solid films of this material is the extreme size of the >8 MDa molecular weight of the virgin, as-received material. Reduction of this molecular weight by factors of up to 40 is achieved by high power sonication. To support the various measurements that have been made to confirm that the sonicated material is still double strand DNA and to look for other effects of sonication, Raman studies were carried out to compare the spectra over a wide range of molecular weights and to develop baseline data that can be used in intercolation studies where various dopants are added to change the electrical, mechanical or optical properties. Raman microprobe spectra from solid, dry thin films of DNA with molecular weights ranging from 200 kDa to >8 MDa complexed with cetyltrimethyl-ammonium chloride (CTMA) are reported and compared to the as-received spectrum and to published DNA spectra in aqueous solutions. In addition, microscopy and measurements on macro-molecular structures of DNA-CTMA are reported.

  18. SPECTROSCOPIC STUDIES OF STRUCTURE, DYNAMICS AND REACTIVITY IN IONIC LIQUIDS.

    SciTech Connect

    WISHART,J.F.

    2007-11-30

    Ionic liquids (ILs) are a rapidly expanding family of condensed-phase media with important applications in energy production, nuclear fuel and waste processing, improving the efficiency and safety of industrial chemical processes, and pollution prevention. ILs are generally nonvolatile, noncombustible, highly conductive, recyclable and capable of dissolving a wide variety of materials. They are finding new uses in chemical synthesis, catalysis, separations chemistry, electrochemistry and other areas. Ionic liquids have dramatically different properties compared to conventional molecular solvents, and they provide a new and unusual environment to test our theoretical understanding of charge transfer and other reactions. We are interested in how IL properties influence physical and dynamical processes that determine the stability and lifetimes of reactive intermediates and thereby affect the courses of chemical reactions and product distributions. Successful use of ionic liquids in radiation-filled environments, where their safety advantages could be significant, requires an understanding of ionic liquid radiation chemistry. For example, characterizing the primary steps of IL radiolysis will reveal radiolytic degradation pathways and suggest ways to prevent them or mitigate their effects on the properties of the material. An understanding of ionic liquid radiation chemistry will also facilitate pulse radiolysis studies of general chemical reactivity in ILs, which will aid in the development of applications listed above. Very early in our radiolysis studies it became evident that slow solvation dynamics of the excess electron in ILs (which vary over a wide viscosity range) increases the importance of pre-solvated electron reactivity and consequently alters product distributions. Parallel studies of IL solvation phenomena using coumarin-153 dynamic Stokes shifts and polarization anisotropy decay rates are done to compare with electron solvation studies and to evaluate

  19. Chemical and spectroscopic studies of Cercidium praecox gum exudate.

    PubMed

    León de Pinto, G; Martínez, M; Rivas, C

    1994-07-01

    The structure of the polysaccharide from Cercidium praecox (R&P) Harms gum exudate has been studied by Smith degradation, by sugar and methylation analyses, and by 13C NMR spectroscopy. The results showed a (1-->4)-xylan core. Some xylose residues are substituted at O-2 by alpha-D-glucuronic acid and 4-O-methyl-alpha-D-glucuronic acid residues. beta-D-Glucuronic acid is present, probably as terminal residues. The arabinose is present as alpha-L-furanose and beta-L-pyranose. PMID:8062287

  20. Spectroscopic, thermal and structural studies on manganous malate crystals

    SciTech Connect

    Thomas, J. Lincy, A. Mahalakshmi, V.; Saban, K. V.

    2013-01-15

    Prismatic crystals of manganous malate have been prepared by controlled ionic diffusion in hydrosilica gel. The structure was elucidated using single crystal X-ray diffraction. The crystals are orthorhombic with space group Pbca. Vibrations of the functional groups were identified by the FTIR spectrum. Thermogravimetric and differential thermal analyses (TG-DTA) were carried out to explore the thermal decomposition pattern of the material. Structural information derived from FTIR and TG-DTA studies is in conformity with the single crystal XRD data.

  1. Electrochemical and spectroscopic studies of fuel cell reactions

    NASA Astrophysics Data System (ADS)

    Shao, Minhua

    Fuel cells, especially proton exchange membrane fuel cells (PEMFCs) are expected soon to become a major source of clean energy. However, the sluggish kinetics of the fuel cell reactions, i.e., the fuel oxidation and oxygen reduction, hinders the wide-spread application of PEMFCs. These problems prompted our studies to focus on elucidating the nature of the reaction intermediates during the oxidation of fuels and the reduction of oxygen on electrocatalysts, and understanding the mechanisms of these reactions. The results from these studies will provide basic information for designing new electrocatalysts. In this dissertation, the oxidation reactions of ethanol and dimethyl ether (DME) on Pt were investigated by the surface enhanced infrared absorption spectroscopy with an attenuated total reflection configuration (ATR-SEIRAS). Various reaction intermediates were detected and their electrochemical behaviors were studied. We also benefited from advantages of the ATR-SEIRAS technique and observed superoxide anion (O2-) and hydrogen peroxide anion (H2-) as the intermediates in the oxygen reduction reaction (ORR) on Pt and Au electrodes for the first time. The other main goal of this study is design of new electrocatalysts for ORR with low cost and high activity. Two novel electrocatalysts were developed. One is Pt monolayer electrocatalysts consisting of a Pt monolayer formed by a red-ox replacement of the Cu monolayer by Pt atoms on non-noble metal-noble metal core-shell nanoparticles. In such catalyst, the total noble mass activity of the catalyst was 2--6 times larger that of commercial Pt catalyst. Another way of lowering the cost of catalysts and enhancing the ORR activity involves alloying less expensive noble metals with other non-noble elements. In this dissertation, the nano-structured Pd based alloy electrocatalysts have been explored. The results showed that their ORR activities surpass that of commercial Pt. The density functional theory (DFT) calculations

  2. Infrared micro-spectroscopic studies of epithelial cells

    PubMed Central

    Romeo, Melissa; Mohlenhoff, Brian; Jennings, Michael; Diem, Max

    2009-01-01

    We report results from a study of human and canine mucosal cells, investigated by infrared micro-spectroscopy, and analyzed by methods of multivariate statistics. We demonstrate that the infrared spectra of individual cells are sensitive to the stage of maturation, and that a distinction between healthy and diseased cells will be possible. Since this report is written for an audience not familiar with infrared micro-spectroscopy, a short introduction into this field is presented along with a summary of principal component analysis. PMID:16797481

  3. Photoelectron spectroscopic study of the ethyl cyanoacrylate anion

    NASA Astrophysics Data System (ADS)

    Zhang, Xinxing; Tang, Xin; Bowen, Kit

    2013-09-01

    Anion photoelectron spectroscopy and density functional theory have been utilized to study the parent, ethyl cyanoacrylate molecular anion, ECA-. The measured electron affinity (0.9 ± 0.2 eV), vertical detachment energy (1.3 ± 0.1 eV), and anion-to-triplet neutral, photodetachment transition energies (4.0 ± 0.1 eV and 4.5 ± 0.1 eV) all compare well with their calculated values. The relatively high electron affinity of the ECA monomer is responsible for the fact that its “anionic” polymerization mechanism proceeds even with weak nucleophiles, such as water.

  4. Raman and infrared spectroscopic study of turquoise minerals.

    PubMed

    Čejka, Jiří; Sejkora, Jiří; Macek, Ivo; Malíková, Radana; Wang, Lina; Scholz, Ricardo; Xi, Yunfei; Frost, Ray L

    2015-10-01

    Raman and infrared spectra of three well-defined turquoise samples, CuAl6(PO4)4(OH)8·4H2O, from Lavender Pit, Bisbee, Cochise county, Arizona; Kouroudaiko mine, Faleme river, Senegal and Lynch Station, Virginia were studied, interpreted and compared. Observed Raman and infrared bands were assigned to the stretching and bending vibrations of phosphate tetrahedra, water molecules and hydroxyl ions. Approximate O-H⋯O hydrogen bond lengths were inferred from the Raman and infrared spectra. No Raman and infrared bands attributable to the stretching and bending vibrations of (PO3OH)(2-) units were observed. PMID:25956330

  5. Raman and infrared spectroscopic study of turquoise minerals

    NASA Astrophysics Data System (ADS)

    Čejka, Jiří; Sejkora, Jiří; Macek, Ivo; Malíková, Radana; Wang, Lina; Scholz, Ricardo; Xi, Yunfei; Frost, Ray L.

    2015-10-01

    Raman and infrared spectra of three well-defined turquoise samples, CuAl6(PO4)4(OH)8·4H2O, from Lavender Pit, Bisbee, Cochise county, Arizona; Kouroudaiko mine, Faleme river, Senegal and Lynch Station, Virginia were studied, interpreted and compared. Observed Raman and infrared bands were assigned to the stretching and bending vibrations of phosphate tetrahedra, water molecules and hydroxyl ions. Approximate O-H⋯O hydrogen bond lengths were inferred from the Raman and infrared spectra. No Raman and infrared bands attributable to the stretching and bending vibrations of (PO3OH)2- units were observed.

  6. Vibrational spectroscopic studies of adsorbates on bimetallic surfaces. Doctoral thesis

    SciTech Connect

    Kuhn, W.K.

    1992-12-01

    In this work, well-defined bimetallic surfaces have been studied using carbon monoxide adsorption in conjunction with infrared reflection absorption spectroscopy (IRAS). These studies have indicated that for CO adsorbed on Cu overlayers, the bond between the CO and the Cu adatoms is comprised of both pi-back-donation and polarization interaction components. The sum of the contributions from these effects determines the observed bond strength with the observed CO stretching frequency being determined by the relative contributions of the components. In addition, it was determined that IR spectra of adsorbed CO show a remarkable sensitivity to surface structure. Three-dimensional Cu clusters, well-ordered two dimensional Cu islands and isolated Cu atoms are distinctively characterized by their CO IR peaks. In addition, both disorder-order and order-order transitions are observed for the metal overlayers on the single crystal metal substrates. It was also observed that localized segregation and ordering of mixed Co and S overlayers on a Mo(110) substrate occurs upon annealing.

  7. Thermo-active polymer nanocomposites: a spectroscopic study

    NASA Astrophysics Data System (ADS)

    Winter, A. Douglas; Larios, Eduardo; Jaye, Cherno; Fischer, Daniel A.; Omastová, Mária; Campo, Eva M.

    2014-09-01

    Photo- and thermo-mechanical actuation behaviour in specific polymer-carbon nanotube composites has been observed in recent years and studied at the macroscale. These systems may prove to be suitable components for a wide range of applications, from MOEMs and nanotechnology to neuroscience and tissue engineering. Absence of a unified model for actuation behaviour at a molecular level is hindering development of such smart materials. We observed thermomechanical actuation of ethylene-vinyl acetate | carbon nanotube composites through in situ near-edge X-ray absorption fine structure spectroscopy to correlate spectral trends with macroscopic observations. This paper presents spectra of composites and constituents at room temperature to identify resonances in a building block model, followed by spectra acquired during thermo-actuation. Effects of strain-induced filler alignment are also addressed. Spectral resonances associated with C=C and C=O groups underwent synchronised intensity variations during excitation, and were used to propose a conformational model of actuation based on carbon nanotube torsion. Future actuation studies on other active polymer nanocomposites will verify the universality of the proposed model.

  8. Raman spectroscopic study of Lactarius spores (Russulales, Fungi).

    PubMed

    De Gussem, Kris; Vandenabeele, Peter; Verbeken, Annemieke; Moens, Luc

    2005-10-01

    Fungi are important organisms in ecosystems, in industrial and pharmaceutical production and are valuable food sources as well. Classical identification is often time-consuming and specialistic. In this study, Raman spectroscopy is applied to the analysis of fungal spores of Lactarius, an economically and ecologically important genus of Basidiomycota. Raman spectra of spores of Lactarius controversus Pers.: Fr., Lactarius lacunarum (Romagn.) ex Hora, Lactarius quieticolor Romagn. and Lactarius quietus (Fr.: Fr.) Fr. are reported for the first time. The spectra of these species show large similarity. These spectra are studied and compared with the Raman spectra of reference substances known to occur in macrofungi, including saccharides, lipids and some minor compounds that may serve as specific biomarkers (adenine, ergosterol and glycine). Most Raman bands could be attributed to specific components. In agreement with the biological role of fungal spores, high amounts of lipids were observed, the main fatty acid being oleate. In addition to different types of lipids and phospholipids, the polysaccharides chitin and amylopectin could be detected as well. The presence of trehalose is not equivocally shown, due to overlapping bands. Raman band positions are reported for the observed bands of the different species and reference products. PMID:16165029

  9. Raman spectroscopic study of Lactarius spores (Russulales, Fungi)

    NASA Astrophysics Data System (ADS)

    De Gussem, Kris; Vandenabeele, Peter; Verbeken, Annemieke; Moens, Luc

    2005-10-01

    Fungi are important organisms in ecosystems, in industrial and pharmaceutical production and are valuable food sources as well. Classical identification is often time-consuming and specialistic. In this study, Raman spectroscopy is applied to the analysis of fungal spores of Lactarius, an economically and ecologically important genus of Basidiomycota. Raman spectra of spores of Lactarius controversus Pers.: Fr., Lactarius lacunarum (Romagn.) ex Hora, Lactarius quieticolor Romagn. and Lactarius quietus (Fr.: Fr.) Fr. are reported for the first time. The spectra of these species show large similarity. These spectra are studied and compared with the Raman spectra of reference substances known to occur in macrofungi, including saccharides, lipids and some minor compounds that may serve as specific biomarkers (adenine, ergosterol and glycine). Most Raman bands could be attributed to specific components. In agreement with the biological role of fungal spores, high amounts of lipids were observed, the main fatty acid being oleate. In addition to different types of lipids and phospholipids, the polysaccharides chitin and amylopectin could be detected as well. The presence of trehalose is not equivocally shown, due to overlapping bands. Raman band positions are reported for the observed bands of the different species and reference products.

  10. Photoacoustic FTIR spectroscopic study of undisturbed nacre from red abalone

    NASA Astrophysics Data System (ADS)

    Verma, Devendra; Katti, Kalpana; Katti, Dinesh

    2006-07-01

    In this work, photoacoustic Fourier transform infrared (PA-FTIR) spectroscopy has been utilized to study interfacial interactions of undisturbed nacre and nacre powder from red abalone shell. The spectra of both undisturbed nacre and nacre powder showed characteristic bands of aragonite and proteins. Although nacre powder and undisturbed nacre are chemically identical, PA-FTIR spectrum of undisturbed nacre is found to be significantly different from that of nacre powder. A broad and strong band is observed at around 1485 cm -1 in nacre powder. The intensity of this band is notably reduced in undisturbed nacre. This result is explained on the basis of interfacial interactions between aragonite platelets and acidic proteins. It is also observed that band at around 1788 cm -1 originates from three overlapping bands 1797, 1787 and 1778 cm -1. The band at around 1787 cm -1 is assigned to C dbnd O stretching of carboxylate groups of acidic proteins. The other two bands at 1797 and 1778 cm -1, originate from aragonite and have been assigned to combination bands, ν 3 + ν 4a and ν 3 + ν 4b, respectively. For the study of stratification in undisturbed nacre, PA-FTIR spectra have been collected in step scan mode. The variation in spectra with depth can be attributed to changes in conformation of proteins as well as interfacial interactions.

  11. Rotational Spectroscopic Studies and Observational Searches for HO3

    NASA Astrophysics Data System (ADS)

    Widicus Weaver, Susanna

    Interstellar chemistry is largely driven by reactions of unstable molecules that serve as reaction intermediates in terrestrial chemistry. One such class of compounds are weakly-bound clusters. These clusters could form in interstellar environments through radiative association reactions, but their identification and characterization in interstellar environments is limited by a lack of rotational spectral information. One such species is HO3, which could be formed in the interstellar medium from O2 and OH. HO3 has been studied extensively in the infrared, and there are a few microwave spectral studies that have also been reported. However, no millimeter or submillimeter spectral information is available to guide astronomical observations. In this talk, we will present the laboratory characterization of trans -HO3 and trans -DO3 from 70 to 450 GHz using our newly developed fast sweeping technique. The molecular constants have been significantly refined, and additional higher order centrifugal distortion constants have been determined. We will also present an initial observational search for HO3 in 32 star forming regions. Although no HO3 lines have been detected thus far, strict upper limits can be placed on the HO3 column density in these sources based on this analysis. Additional Authors: Luyao Zou, Brian M. Hays.

  12. Ligand exchange in quaternary alloyed nanocrystals--a spectroscopic study.

    PubMed

    Gabka, Grzegorz; Bujak, Piotr; Giedyk, Kamila; Kotwica, Kamil; Ostrowski, Andrzej; Malinowska, Karolina; Lisowski, Wojciech; Sobczak, Janusz W; Pron, Adam

    2014-11-14

    Exchange of initial, predominantly stearate ligands for pyridine in the first step and butylamine (BA) or 11-mercaptoundecanoic acid (MUA) in the second one was studied for alloyed quaternary Cu-In-Zn-S nanocrystals. The NMR results enabled us to demonstrate, for the first time, direct binding of the pyridine labile ligand to the nanocrystal surface as evidenced by paramagnetic shifts of the three signals attributed to its protons to 7.58, 7.95 and 8.75 ppm. XPS investigations indicated, in turn, a significant change in the composition of the nanocrystal surface upon the exchange of initial ligands for pyridine, which being enriched in indium in the 'as prepared' form became enriched in zinc after pyridine binding. This finding indicated that the first step of ligand exchange had to involve the removal of the surface layer enriched in indium with simultaneous exposure of a new, zinc-enriched layer. In the second ligand exchange step (replacement of pyridine with BA or MUA) the changes in the nanocrystal surface compositions were much less significant. The presence of zinc in the nanocrystal surface layer turned out necessary for effective binding of pyridine as shown by a comparative study of ligand exchange in Cu-In-Zn-S, Ag-In-Zn-S and CuInS2, carried out by complementary XPS and NMR investigations. PMID:25252174

  13. Charge Carrier Conduction Mechanism in PbS Quantum Dot Solar Cells: Electrochemical Impedance Spectroscopy Study.

    PubMed

    Wang, Haowei; Wang, Yishan; He, Bo; Li, Weile; Sulaman, Muhammad; Xu, Junfeng; Yang, Shengyi; Tang, Yi; Zou, Bingsuo

    2016-07-20

    With its properties of bandgap tunability, low cost, and substrate compatibility, colloidal quantum dots (CQDs) are becoming promising materials for optoelectronic applications. Additionally, solution-processed organic, inorganic, and hybrid ligand-exchange technologies have been widely used in PbS CQDs solar cells, and currently the maximum certified power conversion efficiency of 9.9% has been reported by passivation treatment of molecular iodine. Presently, there are still some challenges, and the basic physical mechanism of charge carriers in CQDs-based solar cells is not clear. Electrochemical impedance spectroscopy is a monitoring technology for current by changing the frequency of applied alternating current voltage, and it provides an insight into its electrical properties that cannot be measured by direct current testing facilities. In this work, we used EIS to analyze the recombination resistance, carrier lifetime, capacitance, and conductivity of two typical PbS CQD solar cells Au/PbS-TBAl/ZnO/ITO and Au/PbS-EDT/PbS-TBAl/ZnO/ITO, in this way, to better understand the charge carriers conduction mechanism behind in PbS CQD solar cells, and it provides a guide to design high-performance quantum-dots solar cells. PMID:27176547

  14. Sensitivity study of an ultrasound coupled transrectal electrical Impedance Tomography system for prostate imaging

    NASA Astrophysics Data System (ADS)

    Wan, Y.; Halter, R.; Borsic, A.; Manwaring, P.; Hartov, A.; Paulsen, K.

    2010-04-01

    In 2009, prostate cancer ranks as the most common cancer and the second most fatal cancer in men in the United States. Unfortunately, the current clinical diagnostic methods (e.g. prostate-specific antigen (PSA), digital rectal examination, endorectal MRI, transrectal ultrasound, biopsy) used for detecting and staging prostate cancer are limited. It has been shown that cancerous prostate tissue has significantly different electrical properties when compared to benign tissues. Based on these electrical property findings, a TransRectal Electrical Impedance Tomography (TREIT) system is proposed as a novel prostate imaging modality. The TREIT system is comprised of an array of electrodes interfaced with a clinical TransRectal UltraSound (TRUS) probe. We evaluate this imaging system through series of phantom imaging experiments to assess the system's ability to image high and low contrast objects at various positions. We found that the TREIT system can easily discern high contrast inclusions of 1 cm in diameter at distances centered at 2 times the radius of the TREIT probe away from the probe surface. Furthermore, this technology's ability to detect low contrast inclusions suggests that it has the potential to successfully detect prostate cancer.

  15. Electrical impedance myography for the assessment of children with muscular dystrophy: a preliminary study

    NASA Astrophysics Data System (ADS)

    Rutkove, S. B.; Darras, B. T.

    2013-04-01

    Electrical impedance myography (EIM) provides a non-invasive approach for quantifying the severity of neuromuscular disease. Here we determine how well EIM data correlates to functional and ultrasound (US) measures of disease in children with Duchenne muscular dystrophy (DMD) and healthy subjects. Thirteen healthy boys, aged 2-12 years and 14 boys with DMD aged 4-12 years underwent both EIM and US measurements of deltoid, biceps, wrist flexors, quadriceps, tibialis anterior, and medial gastrocnemius. EIM measurements were performed with a custom-designed probe using a commercial multifrequency bioimpedance device. US luminosity data were quantified using a gray-scale analysis approach. Children also underwent the 6-minute walk test, timed tests and strength measurements. EIM and US data were combined across muscles. EIM 50 kHz phase was able to discriminate DMD children from healthy subjects with 98% accuracy. In the DMD patients, average EIM phase measurements also correlated well with standard functional measures. For example the 50 kHz phase correlated with the Northstar Ambulatory Assessment test (R = 0.83, p = 0.02). EIM 50 kHz phase and US correlated as well, with R = -0.79 (p < 0.001). These results show that EIM provides valuable objective measures Duchenne muscular dystrophy severity.

  16. Soybean oil in water-borne coatings and latex film formation study by AC impedance

    NASA Astrophysics Data System (ADS)

    Jiratumnukul, Nantana

    Conventional coalescing agents such as butyl cellosolve, butyl carbitol, and TexanolRTM are widely use in the latex coatings industry to facilitate film formation at ambient temperature. Coalescent aids are composed of solvents with low evaporation rates. After water evaporates, coalescent aids would help soften polymer molecules and form continuous films, then gradually evaporates from the film. Coalescent aids, therefore, are considered as volatile organic compounds (VOC), which are of environmental concern. The main purpose of this research project was to prepare a fatty acid glycol ester from soybean oil and glycol (polyols). The soybean oil glycol ester can be used as a coalescent aid in latex paint formulation. The soybean oil glycol ester not only lowered the minimum film formation temperature of latex polymers and continuous film formed at ambient temperature, but also after it has facilitated film formation, does not substantially evaporate, but becomes part of the film. Soybean oil glycol esters, therefore, can reduce the VOC levels and facilitate film formation of latex paints. In the second part of this research AC-Impedance was used to investigate the efficiency of soybean oil coalescent aid in latex film formation relative to the conventional ones. The coating resistance showed that the efficiency of film formation was increased as a function of dry time. The coating resistance also exhibited the effect of soybean oil ester in latex film formation in the same fashion as a conventional coalescent aid, TexanolRTM.

  17. Effects of Operating Conditions on Internal Resistances in Enzyme Fuel Cells Studied via Electrochemical Impedance Spectroscopy

    SciTech Connect

    Aaron, D; Borole, Abhijeet P; Yiacoumi, Sotira; Tsouris, Costas

    2012-01-01

    Enzyme fuel cells (EFCs) offer some advantages over traditional precious-metal-catalyzed fuel cells, such as polymer electrolyte membrane fuel cells (PEMFCs). However, EFCs exhibit far less power output than PEMFCs and have relatively short life spans before materials must be replaced. In this work, electrochemical impedance spectroscopy (EIS) is used to analyze the internal resistances throughout the EFC at a variety of operating conditions. EIS analysis is focused primarily on the resistances of the anode, solution/membrane, and cathode. Increased enzyme loading results in improved power output and reductions in internal resistance. Conditions are identified for which enzyme loading does not limit the EFC performance. EIS experiments are also reported for EFCs operated continuously for 2 days; power output declines sharply over time, while all internal resistances increase. Drying of the cathode and enzyme/mediator degradation are believed to have contributed to this behavior. Finally, experiments are performed at varying air-humidification temperatures. Little effect on internal resistances or power output is observed. However, it is anticipated that increased air humidification can improve longevity by delivering more water to the cathode. Improvements to the enzymatic cathode are needed for EFC development. These improvements need to focus on improving transport rather than increasing enzyme loading.

  18. Theoretical spectroscopic studies on chemical and electronic structures of arginylglycine.

    PubMed

    Li, Hongbao; Li, Leilei; Jiang, Jun; Lin, Zijing; Luo, Yi

    2015-10-14

    The energy differences between canonical and zwitterionic isomers of arginylglycine (ArgGly) at the CCSD/aug-cc-pVDZ level are too small (less than 1 kcal mol(-1)) to determine the dominant form in the gas phase from the energetic point of view. First-principles simulations have been performed for near-edge X-ray absorption fine-structure (NEXAFS) spectra and X-ray photoelectron spectra (XPS) at C, N and O K-edges, as well as for infrared (IR) spectra of neutral ArgGly. Noticeable spectral differences were found which enable the unambiguous identification of different neutral groups. We thus demonstrate X-ray spectroscopy as a powerful technique to study the conformation dependent chemical and electronic properties of neutral ArgGly. PMID:26266331

  19. Preparations and spectroscopic studies of organotin complexes of diclofenac*1

    NASA Astrophysics Data System (ADS)

    Kourkoumelis, Nikolaos; Demertzis, Mavroudis A.; Kovala-Demertzi, Dimitra; Koutsodimou, Aglaia; Moukarika, Alice

    2004-08-01

    The reactions of the potent and widely used anti-inflammatory drug diclofenac, HL, with diorganotin(IV) oxides were studied. The dimeric tetraorganodistannoxane complexes [Me 2LSnOSnLMe 2] 2, [Bu 2LSnOSnLBu 2] 2, [Ph 2LSnOSnLPh 2] 2 and the dibutyltin complex [Bu 2SnL 2], have been prepared and structurally characterized in the solid state by means of vibrational and 119Sn Mössbauer spectroscopy. Determination of lattice dynamics by temperature-dependent 119Sn Mössbauer spectroscopy. From the variable-temperature Mössbauer effect, the Debye temperature was determined. The complexes have been characterized in solution by NMR ( 1H and 13C) spectroscopy. Vibrational, Mössbauer, and NMR data are discussed in terms of the proposed structures.

  20. High resolution spectroscopic study of Be10Lambda;

    NASA Astrophysics Data System (ADS)

    Gogami, T.; Chen, C.; Kawama, D.; Achenbach, P.; Ahmidouch, A.; Albayrak, I.; Androic, D.; Asaturyan, A.; Asaturyan, R.; Ates, O.; Baturin, P.; Badui, R.; Boeglin, W.; Bono, J.; Brash, E.; Carter, P.; Chiba, A.; Christy, E.; Danagoulian, S.; de Leo, R.; Doi, D.; Elaasar, M.; Ent, R.; Fujii, Y.; Fujita, M.; Furic, M.; Gabrielyan, M.; Gan, L.; Garibaldi, F.; Gaskell, D.; Gasparian, A.; Han, Y.; Hashimoto, O.; Horn, T.; Hu, B.; Hungerford, Ed. V.; Jones, M.; Kanda, H.; Kaneta, M.; Kato, S.; Kawai, M.; Khanal, H.; Kohl, M.; Liyanage, A.; Luo, W.; Maeda, K.; Margaryan, A.; Markowitz, P.; Maruta, T.; Matsumura, A.; Maxwell, V.; Mkrtchyan, A.; Mkrtchyan, H.; Nagao, S.; Nakamura, S. N.; Narayan, A.; Neville, C.; Niculescu, G.; Niculescu, M. I.; Nunez, A.; Nuruzzaman, Okayasu, Y.; Petkovic, T.; Pochodzalla, J.; Qiu, X.; Reinhold, J.; Rodriguez, V. M.; Samanta, C.; Sawatzky, B.; Seva, T.; Shichijo, A.; Tadevosyan, V.; Tang, L.; Taniya, N.; Tsukada, K.; Veilleux, M.; Vulcan, W.; Wesselmann, F. R.; Wood, S. A.; Yamamoto, T.; Ya, L.; Ye, Z.; Yokota, K.; Yuan, L.; Zhamkochyan, S.; Zhu, L.; Hksjlab E05-115 Collaboration

    2016-03-01

    Spectroscopy of a Be10Lambda; hypernucleus was carried out at JLab Hall C using the (e ,e'K+) reaction. A new magnetic spectrometer system (SPL+HES+HKS), specifically designed for high resolution hypernuclear spectroscopy, was used to obtain an energy spectrum with a resolution of ˜0.78 MeV (FWHM). The well-calibrated spectrometer system of the present experiment using p (e ,e'K+)Λ ,Σ0 reactions allowed us to determine the energy levels; and the binding energy of the ground-state peak (mixture of 1- and 2- states) was found to be BΛ=8.55 ±0.07 (stat . ) ±0.11 (sys . ) MeV. The result indicates that the ground-state energy is shallower than that of an emulsion study by about 0.5 MeV which provides valuable experimental information on the charge symmetry breaking effect in the Λ N interaction.

  1. Raman and infrared spectroscopic study of kamphaugite-(Y)

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; López, Andrés; Scholz, Ricardo

    2015-05-01

    We have studied the carbonate mineral kamphaugite-(Y)(CaY(CO3)2(OH)·H2O), a mineral which contains yttrium and specific rare earth elements. Chemical analysis shows the presence of Ca, Y and C. Back scattering SEM appears to indicate a single pure phase. The vibrational spectroscopy of kamphaugite-(Y) was obtained using a combination of Raman and infrared spectroscopy. Two distinct Raman bands observed at 1078 and 1088 cm-1 provide evidence for the non-equivalence of the carbonate anion in the kamphaugite-(Y) structure. Such a concept is supported by the number of bands assigned to the carbonate antisymmetric stretching mode. Multiple bands in the ν4 region offers further support for the non-equivalence of carbonate anions in the structure. Vibrational spectroscopy enables aspects of the structure of the mineral kamphaugite-(Y) to be assessed.

  2. Spectroscopic study of low-temperature hydrogen absorption in palladium

    SciTech Connect

    Ienaga, K. Takata, H.; Onishi, Y.; Inagaki, Y.; Kawae, T.; Tsujii, H.; Kimura, T.

    2015-01-12

    We report real-time detection of hydrogen (H) absorption in metallic palladium (Pd) nano-contacts immersed in liquid H{sub 2} using inelastic electron spectroscopy (IES). After introduction of liquid H{sub 2}, the spectra exhibit the time evolution from the pure Pd to the Pd hydride, indicating that H atoms are absorbed in Pd nano-contacts even at the temperature where the thermal process is not expected. The IES time and bias voltage dependences show that H absorption develops by applying bias voltage 30 ∼ 50 mV, which can be explained by quantum tunneling. The results represent that IES is a powerful method to study the kinetics of high density H on solid surface.

  3. Micro-Ft Spectroscopic Studies of Breast Tissues

    NASA Astrophysics Data System (ADS)

    Anastassopoulou, J.; Arapantoni, P.; Boukaki, E.; Konstadoudakis, S.; Theophanides, T.; Valavanis, C.; Conti, C.; Ferraris, P.; Giorgini, G.; Sabbatini, S.; Tosi, G.

    Micro-FT-IR spectroscopy was used to study breast cancer tissues and, in particular osteosarcoma tissue. By analysing the spectra, we have found characteristic bands in the infrared regions, where the main components of these signature bands are located. In the region between 1680-1660 cm-1 are found the characteristic bands of Amide I and II of proteins. The bands, which correspond to the vibrations of the phosphate groups, are found in the region near 1140-900 cm-1. These characteristic bands have been monitored as a function of the degree of cancer progression. The results have been obtained with chemometric methods, such as cluster analysis, principal component analysis and custom analysis in order to distinguish the neoplastic zones from the normal zones.

  4. Mechanism of Arsenic Adsorption Using Wheat Biomass -- a spectroscopic study

    NASA Astrophysics Data System (ADS)

    Calvo, Oscar; Manciu, Felicia; Maldonado, Josefina; Gardea-Torresdey, Jorge

    2006-10-01

    Arsenic is a trace element that is toxic to animals, humans included. Since the current Environmental Protection Agency guidelines regarding water quality standards indicate that arsenic concentrations in excess of 50 ppb are hazardous to welfare of humans, the search for new water remediation methods or improvements of previous methods have been a focus in environmental technology. Investigations of arsenic uptake have used wide range of sorbents including iron oxides and oxyhydroxides, for which it have been proved that arsenic shows high affinity. In this study, we used far-infrared spectroscopy to examine the arsenic reduction using biomaterials. pH dependence analysis by FTIR demonstrates the sorption of iron oxides and oxyhydroxides by the wheat biomass. The splitting of 350 cm-1 amorphous iron oxide vibrations is a direct proof of the arsenic uptake. In addition, there is evidence of sorption of arsenic at sulfhydryl group of cysteine existent in wheat.

  5. In-beam spectroscopic studies of the 44S nucleus

    NASA Astrophysics Data System (ADS)

    Cáceres, L.; Sohler, D.; Grévy, S.; Sorlin, O.; Dombrádi, Zs.; Bastin, B.; Achouri, N. L.; Angélique, J. C.; Azaiez, F.; Baiborodin, D.; Borcea, R.; Bourgeois, C.; Buta, A.; Bürger, A.; Chapman, R.; Dalouzy, J. C.; Dlouhy, Z.; Drouard, A.; Elekes, Z.; Franchoo, S.; Gaudefroy, L.; Iacob, S.; Laurent, B.; Lazar, M.; Liang, X.; Liénard, E.; Mrazek, J.; Nalpas, L.; Negoita, F.; Nowacki, F.; Orr, N. A.; Penionzhkevich, Y.; Podolyák, Zs.; Pougheon, F.; Poves, A.; Roussel-Chomaz, P.; Saint-Laurent, M. G.; Stanoiu, M.; Stefan, I.

    2012-02-01

    The structure of the 44S nucleus has been studied at GANIL through the one proton knock-out reaction from a 45Cl secondary beam at 42 A·MeV. The γ rays following the de-excitation of 44S were detected in flight using the 70 BaF2 detectors of the Château de Cristal array. An exhaustive γγ-coincidence analysis allowed an unambiguous construction of the level scheme up to an excitation energy of 3301 keV. The existence of the spherical 22+ state is confirmed and three new γ-ray transitions connecting the prolate deformed 21+ level were observed. Comparison of the experimental results to shell model calculations further supports a prolate and spherical shape coexistence with a large mixing of states built on the ground state band in 44S.

  6. Raman spectroscopic study of plasma-treated salmon DNA

    SciTech Connect

    Lee, Geon Joon; Kim, Yong Hee; Choi, Eun Ha; Kwon, Young-Wan

    2013-01-14

    In this research, we studied the effect of plasma treatment on the optical/structural properties of the deoxyribonucleic acid (DNA) extracted from salmon sperm. DNA-cetyltrimethylammonium (CTMA) films were obtained by complexation of DNA with CTMA. Circular dichroism (CD) and Raman spectra indicated that DNA retained its double helical structure in the solid film. The Raman spectra exhibited several vibration modes corresponding to the nuclear bases and the deoxyribose-phosphate backbones of the DNA, as well as the alkylchains of CTMA. Dielectric-barrier-discharge (DBD) plasma treatment induced structural modification and damage to the DNA, as observed by changes in the ultraviolet-visible absorption, CD, and Raman spectra. The optical emission spectra of the DBD plasma confirmed that DNA modification was induced by plasma ions such as reactive oxygen species and reactive nitrogen species.

  7. Enhanced Raman spectroscopic study of rotational isomers on metal surfaces

    NASA Technical Reports Server (NTRS)

    Loo, B. H.; Lee, Y. G.; Frazier, D. O.

    1986-01-01

    Surfaced-enhanced Raman spectroscopy has been used to study rotational isomers of succinonitrile and N-methyl-thioacetamide on Cu and Ag surfaces. Both the gauche and trans conformers of succinonitrile are found to chemisorb on the metal surface. The doubly degenerate nu(C-triple bond-N) in the free molecules is removed when succinonitrile adsorbs on copper, which indicates that the two (C-triple bond-N) groups are no longer chemically equivalent. Both conformers are found to coordinate to the copper surface through the pi system of one of the two (C-triple bond-N) groups. In the case of N-methyl-thioacetamide, the population of the cis isomer is greatly increased on Cu and Ag surfaces. This is probably due to surface-induced cis-trans isomerization, in which the predominant trans isomer is converted to the cis isomer.

  8. Phosphonic drugs: Experimental and theoretical spectroscopic studies of fosfomycin

    NASA Astrophysics Data System (ADS)

    Chruszcz-Lipska, Katarzyna; Zborowski, Krzysztof K.; Podstawka-Proniewicz, Edyta; Liu, Shaoxuan; Xu, Yizhuang; Proniewicz, Leonard M.

    2011-02-01

    pH and time-dependant changes of fosfomycin molecular structure in an aqueous solution are studied by Raman, NMR, and generalized 2D correlation spectroscopies. Interpretation of the experimental spectra is based on the assumption of formation of different species running on applied physicochemical conditions. Geometries of all possible structures were entirely optimized with the 6-311++G(2df,p) basis set at the B3LYP theoretical level using procedures implemented in the Gaussian '03 set of programs. Harmonic frequency calculations verified the nature of the studied structures and allowed to simulate obtained Raman spectra. The theoretical NMR shielding was calculated using the GIAO method at the same computational level. In addition, in some cases PCM model was used to monitor the influence of water molecules on the NMR spectra. It is shown that in the pH range of 1-2 of fosfomycin aqueous solution oxirane ring is open sequent to nucleophilic attack and forms 1,2-dihydroxyphosphonic acid with small content of its monodeprotonated species. On the other hand, in pH 7 and higher it appears either as 1,2-epoxypropylphosphonic or 1,2-dihydroxyphosphonic dianion depending upon whether hydrolysis took place or not. It is also discussed that Raman marker bands originating from the individual species of fosfomycin can be used to detect and/or to monitor this antibiotic in an aqueous medium (for example urine samples). Hence, depending upon the structure found in urine one can tell about metabolic processes of this antibiotic in the body.

  9. Raman spectroscopic study of ancient South African domestic clay pottery.

    PubMed

    Legodi, M A; de Waal, D

    2007-01-01

    The technique of Raman spectroscopy was used to examine the composition of ancient African domestic clay pottery of South African origin. One sample from each of four archaeological sites including Rooiwal, Lydenburg, Makahane and Graskop was studied. Normal dispersive Raman spectroscopy was found to be the most effective analytical technique in this study. XRF, XRD and FT-IR spectroscopy were used as complementary techniques. All representative samples contained common features, which were characterised by kaolin (Al2Si2O5(OH)5), illite (KAl4(Si7AlO20)(OH)4), feldspar (K- and NaAlSi3O8), quartz (alpha-SiO2), hematite (alpha-Fe2O3), montmorillonite (Mg3(Si,Al)4(OH)2 x 4.5 5H(2)O[Mg]0.35), and calcium silicate (CaSiO3). Gypsum (CaSO4 x 2H2O) and calcium carbonates (most likely calcite, CaCO3) were detected by Raman spectroscopy in Lydenburg, Makahane and Graskop shards. Amorphous carbon (with accompanying phosphates) was observed in the Raman spectra of Lydenburg, Rooiwal and Makahane shards, while rutile (TiO(2)) appeared only in Makahane shard. The Raman spectra of Lydenburg and Rooiwal shards further showed the presence of anhydrite (CaSO4). The results showed that South African potters used a mixture of clays as raw materials. The firing temperature for most samples did not exceed 800 degrees C, which suggests the use of open fire. The reddish brown and grayish black colours were likely due to hematite and amorphous carbon, respectively. PMID:16839805

  10. Raman spectroscopic studies of carbon in extra-terrestrial materials

    NASA Technical Reports Server (NTRS)

    Macklin, John; Brownlee, Donald; Chang, Sherwood; Bunch, Ted

    1990-01-01

    The measurements obtained here indicate ways in which micro-Raman spectroscopy can be used to elucidate structural characteristics and distribution of carbon in meteorites and interplanetary dust particles (IDPs). Existing information about structurally significant aspects of Raman measurements of graphite is combined with structurally relevant findings from the present micro-Raman studies of carbons prepared by carbonization of polyvinylidine chloride (PVDC) at various temperatures and natural material, as well as several acid residues from the Allende and Murchison meteorites in order to establish new spectra-structure relationships. Structural features of many of the materials in this study have been measured by x ray analysis and electron microscopy: thus, their structural differences can be directly correlated with differences in the Raman spectra. The spectral parameters consequently affirmed as indicators of structure are used as a measure of structure in materials that have unknown carbon structure, especially IDPs. The unique applicability of micro-Raman spectroscopy is realized not only in the ability to conveniently measure spectra of micron-size IDPs, but also micro-sized parts of an inhomogeneous material. Microcrystalline graphite is known to give Raman spectra that differ dependent on crystallite size (see e.g., Lespade, et. al., 1984, or Nemanich and Solin, 1979). The spectral changes that accompany decreasing particle size include increase in the ratio (R) of the intensity of the band near 1350 cm(-1) (D band) to that of the band near 1600 cm(-1) (G band) increase in the half width of the D band (wD) increase in the frequency maximum of the G band and increase in the half-width (wG) of the 2nd order band near 2700 cm(-1) (G) band.

  11. Spectroscopic and HPLC studies of photodegradation of nilvadipine.

    PubMed

    Augustyniak, W; Mielcarek, J; Milewski, M; Szamburska, O

    2001-11-01

    Photochemical decomposition of nilvadipine (NV), a derivative of 1,4-dihydropyridine (DHP), was studied. Photodegradation was carried out in the conditions recommended in the first version of the document issued by the International Conference on Harmonization (ICH), currently in force in the studies of photochemical stability of drugs and therapeutic substances. Methanol solutions of NV were irradiated with a high-pressure mercury arc lamp, type HBO 200 (300-400 nm). The maximum absorption of radiation at 365 nm was achieved by applying the interference filter and Wood's filter. The assessment of NV photodegradation was made on the basis of the UV spectrophotometric and high-performance liquid chromatographic (HPLC) methods. Quantitatively, the process was described with the calculated rate constants of decomposition k, time of decomposition of 50% of the compound to 5, and time of decomposition of 10% of the compound t(0.1). The two methods applied allowed a determination of the kinetic parameters of NV photodegradation from the relationship ln c = f(t). Using the Reinecke salt as a chemical actinometer, apparent quantum yields of photodegradation were obtained; after extrapolation to the time of irradiation zero, these gave the actual quantum yield (phi = 7.3 10(-5)). The quantum yield of fluorescence at lambda(exc) = 375 nm was about 9.3 x 10(-4) The methods used for evaluation of NV photodegradation were subjected to validation, and results of the analytical methods were statistically assessed by Snedecor F and Student t tests. The former test revealed no statistically significant difference between the variances obtained by the HPLC and UV spectrophotometric methods. Also, verification of the zero hypothesis of the Student t test on equality of means of the results obtained gave no significant diferences between the two methods. PMID:11794805

  12. Acidic properties of sulfated zirconia: An infrared spectroscopic study

    SciTech Connect

    Babou, F.; Coudurier, G.; Vedrine, J.C.

    1995-04-01

    Sulfated zirconia with S content of 2 wt.% equivalent to complete coverage of its surface was studied by infrared spectroscopy. At least four sulfated species were identified and exhibited an important and reversible sensitivity to water. These equilibria were demonstrated to exist by the study of adsorption of incremental amounts of water. D{sub 2}O and H{sub 2}{sup 18}O isotopically enriched water molecules were used to assist interpretation of IR spectra. To characterize acidity features, the probe molecules butane, CO, and H{sub 2}O (as weak bases) or pyridine (as a strong base) were adsorbed. Two Lewis acid sites (L{sub 1} and L{sub 2}) were observed and one Bronsted site (B) related to the zirconia support (L{sub 1}) and the sulfated species (L{sub 2}, B). They were evidenced by pyridine adsorption which was shown to partly displace adsorbed sulfate species. With the help of previous theoretical calculations using an ab initio method and representing the zirconia surface by a mononuclear zirconium complex, it is emphasized that the sulfated zirconia can be visualized as a H{sub 2}SO{sub 4} compound grafted onto the surface of zirconia in a way which makes it very sensitive to water but in a reversible way. Its acidity is similar to that of sulfuric acid but it is not really superacidic. Comparison with other oxides leads us to suggest that the cationic charge borne by the metallic cation is of prime importance for the acidity strength. The role of water on the acidic and catalytic properties for n-butane isomerization reaction is emphasized. 33 refs., 11 figs., 2 tabs.

  13. Excitation induced spectroscopic study and quenching effect in cerium samarium codoped lithium aluminoborate glasses

    NASA Astrophysics Data System (ADS)

    Kaur, Parvinder; Kaur, Simranpreet; Singh, Gurinder Pal; Arora, Deepawali; Kumar, Sunil; Singh, D. P.

    2016-08-01

    Lithium aluminium borate host has been codoped with cerium and samarium to prepare glass by conventional melt quench technique. Their structural and spectroscopic investigation has been carried out using XRD, FTIR and density measurements. The UV-Vis absorption spectra and fluorescence spectra (λexc.=380 nm and 400 nm) have been studied for spectroscopic analysis. The amorphous nature of the prepared samples is shown by XRD. The density is increasing with addition of cerium at the expense of aluminium, keeping other components constant. FTIR study also shows the presence of compact and stable tetrahedral BO4 units thus supporting the density results. The UV- Vis absorption spectra show a shift of optical absorption edge towards longer wavelength along with an increase in intensity of peaks with rising samarium concentration. The fluorescence spectra show a blue shift and subsequent suppression of cerium peaks with addition of samarium.

  14. Spectroscopic study of dinitrophenol herbicide sorption on smectite.

    PubMed

    Johnston, C T; Sheng, G; Teppen, B J; Boyd, S A; de Oliveira, M F

    2002-12-01

    Sorption of two dinitrophenolic herbicides, 4,6-dinitro-o-cresol (DNOC) and 4,6-dinitro-2-sec-butylphenol (DINOSEB) to smectite was studied using FTIR, HPLC, and quantum chemical methods. The high affinity of DNOC and DINOSEB for smectite surfaces was attributed to site-specific interactions with exchangeable cations and nonspecific van der Waals interactions with the siloxane surface. The positions of the nu(asym)(NO) and nu(sym)(NO) vibrational modes were perturbed by the exchangeable cations with similar changes occurring for both alkali and alkaline earth cations as a function of ionic potential. The cation-induced changes to the vibrational bands of the NO2 groups indicate that exchangeable metal cations are coordinated to -NO2 groups. Quantum chemical methods predicted a red-shift of the nu(asym)(NO) band and a corresponding blue-shift of the nu(sym)(NO) modes, as was observed experimentally. The nature of the smectite surface itself did not strongly influence the vibrational modes of sorbed DNOC or DINOSEB on the basis of a comparison of DNOC sorbed to three different smectites (K-SWy-2, K-SAz-1, and K-SHCa-1). FTIR spectra of DNOC and DINOSEB sorbed to a K-SWy-2 smectite were studied quantitatively using a modified form of Beers law. The FTIR-derived sorption isotherm of DNOC sorbed to K-SWy-2 was in good agreement with the isotherm derived from HPLC measurements. The molar absorptivity value of DNOC sorbed to K-SWy-2 smectite was 1.43 x 10(7) cm2/mol in good agreement with literature values for nitroaromatics (average value of 1.72 x 10(7) +/- 0.3 cm2/mol). On the basis of this value, the limit of detection using the FTIR method of approximately 5 microgDNOC g(clay) was determined. These two observations (sorption isotherms and molar absorptivity) provide a direct link between the macroscopic sorption results and the FTIR spectra. PMID:12523422

  15. Synthesis, spectroscopic, thermogravimetric and antimicrobial studies of mixed ligands complexes

    NASA Astrophysics Data System (ADS)

    Mahmoud, Walaa H.; Mahmoud, Nessma F.; Mohamed, Gehad G.; El-Sonbati, Adel Z.; El-Bindary, Ashraf A.

    2015-09-01

    An interesting series of mixed ligand complexes have been synthesized by the reaction of metal chloride with guaifenesin (GFS) in the presence of 2-aminoacetic acid (HGly) (1:1:1 molar ratio). The elemental analysis, magnetic moments, molar conductance, spectral (UV-Vis, IR, 1H NMR and ESR) and thermal studies were used to characterize the isolated complexes. The molecular structure of GFS is optimized theoretically and the quantum chemical parameters are calculated. The IR showed that the ligand (GFS) acts as monobasic tridentate through the hydroxyl, phenoxy etheric and methoxy oxygen atoms and co-ligand (HGly) as monobasic bidentate through the deprotonated carboxylate oxygen atom and nitrogen atom of amino group. The molar conductivities showed that all the complexes are non-electrolytes except Cr(III) complex is electrolyte. Electronic and magnetic data proposed the octahedral structure for all complexes under investigation. ESR spectrum for Cu(II) revealed data which confirm the proposed structure. Antibacterial screening of the compounds were carried out in vitro on gram positive (Bacillus subtilis and Staphylococcus aureus), gram negative (Escherichia coli and Neisseria gonorrhoeae) bacteria and for in vitro antifungal activity against Candida albicans organism. However, some complexes showed more chemotherapeutic efficiency than the parent GFS drug. The complexes were also screened for their in vitro anticancer activity against the breast cell line (MFC7) and the results obtained showed that they exhibit a considerable anticancer activity.

  16. Spectroscopic studies of refractory and dielectric thin films

    SciTech Connect

    Truong, C.M.

    1993-01-01

    This work demonstrated the application of the techniques and methodology of surface science to investigate the mechanisms of thin film deposition processes on solid surfaces. The synthesis of boron nitride (BN) thin films was studied using X-ray photoelectron spectroscopy (XPS) and thermal desorption spectroscopy (TDS). In this model system, diborane (B[sub 2]H[sub 6]), ammonia (NH[sub 3]) and hydrazine (N[sub 2]H[sub 4]) were used as precursors to deposit BN thin films on a clean Ru(0001) surface. The result showed that ammonia reaction with diborane yielded only boron-rich boron nitride overlayers. However, stoichiometric BN films in excess of one monolayer could be produced when hydrazine was substituted for ammonia. The effects of oxygen on boron-rich and stoichiometric boron-nitrogen films were also examined. In the second part of this work, high resolution electron energy loss spectroscopy (HREELS) was used to characterize defect centers in MgO and in lithium-doped MgO thin films. The HREELS results showed that MgO thin films grown on Mo(100) were nearly defect-free at temperatures up to 1100 K. HREELS measurements indicated that annealings to higher temperatures induced F-type defect centers in the MgO films. The formation of [Li[sup +]O[sup [minus

  17. Spectroscopic study of neodymium doped lead-bismuth-borate glasses

    NASA Astrophysics Data System (ADS)

    Pasha, Altaf; Dayani, P.; Negalur, Mahesh; Swamy, Manjunatha; Abhiram, J.; Rajaramakrishna, R.

    2016-05-01

    This paper reports on different physical and optical properties of rare earth doped heavy metal oxide glasses. The glass composition of 10Bi2O3-30PbO-60B2O3-xNd2O3 where x = 0, 0.1, 0.2, 0.5 and 1 (in mol %) has been synthesized using melt-quenching technique. Refractive index measurements for these glasses were done and physical parameters were studied. Structural properties of these glasses were analysed through infrared spectra that was recorded between 1600cm-1 and 300cm-1 in transmission mode. The optical absorption spectra were recorded in the wavelength range from 300 to 700 nm. The transitions originated from ground state energy 4I9/2. The energy level analysis has been carried out by considering absorption spectral bands. The results thus obtained are comparable with reports on similar glasses, indicating that the prepared glasses may have potential laser applications.

  18. Spectroscopic studies on the antioxidant activity of ellagic acid.

    PubMed

    Kilic, Ismail; Yeşiloğlu, Yeşim; Bayrak, Yüksel

    2014-09-15

    Ellagic acid (EA, C14H6O8) is a natural dietary polyphenol whose benefits in a variety of diseases shown in epidemiological and experimental studies involve anti-inflammation, anti-proliferation, anti-angiogenesis, anticarcinogenesis and anti-oxidation properties. In vitro radical scavenging and antioxidant capacity of EA were clarified using different analytical methodologies such as total antioxidant activity determination by ferric thiocyanate, hydrogen peroxide scavenging, 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH) scavenging, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity and superoxide anion radical scavenging, ferrous ions (Fe2+) chelating activity and ferric ions (Fe3+) reducing ability. EA inhibited 71.2% lipid peroxidation of a linoleic acid emulsion at 45 μg/mL concentration. On the other hand, butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), α-tocopherol and ascorbic acid displayed 69.8%, 66.8%, 64.5% and 59.7% inhibition on the peroxidation of linoleic acid emulsion at the same concentration, respectively. In addition, EA had an effective DPPH• scavenging, ABTS+ scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, ferric ions (Fe3+) reducing power and ferrous ions (Fe2+) chelating activities. Also, those various antioxidant activities were compared to BHA, BHT, α-tocopherol and ascorbic acid as references antioxidant compounds. These results suggested that EA can be used in the pharmacological, food industry and medicine because of these properties. PMID:24813273

  19. Spectroscopic study on binding of rutin to human serum albumin

    NASA Astrophysics Data System (ADS)

    Pastukhov, Alexander V.; Levchenko, Lidiya A.; Sadkov, Anatoli P.

    2007-10-01

    Steady-state and time-resolved fluorescence spectroscopy techniques were used to study the interaction of the flavonoid rutin with human serum albumin (HSA) as well as spectral properties of the protein-bound flavonoid. Both quenching of the intrinsic fluorescence of the protein (Trp214) and the ligand fluorescence, appearing upon complexation with HSA, were used to determine binding parameters. The binding constant determined from the quenching of the Trp214 fluorescence by rutin is equal to 6.87 ± 0.22 × 10 4 M -1 and that obtained from the fluorescence of HSA-bound rutin is 3.8 ± 0.4 × 10 4 M -1. Based on the Job plot analysis, the 1:1 binding stoichiometry for the HSA-rutin complex was determined. The efficient quenching of the Trp214 fluorescence by rutin, fluorescence resonance energy transfer from excited Trp214 to rutin, and competitive binding of warfarin indicate that the binding site for the flavonoid is situated within subdomain IIA of HSA. The presence of the sugar moiety in the flavonoid molecule reduces affinity of rutin for binding to HSA but does not affect the binding stoichiometry and location of the binding site compared with aglycone analogues.

  20. HPLC assisted Raman spectroscopic studies on bladder cancer

    NASA Astrophysics Data System (ADS)

    Zha, W. L.; Cheng, Y.; Yu, W.; Zhang, X. B.; Shen, A. G.; Hu, J. M.

    2015-04-01

    We applied confocal Raman spectroscopy to investigate 12 normal bladder tissues and 30 tumor tissues, and then depicted the spectral differences between the normal and the tumor tissues and the potential canceration mechanism with the aid of the high-performance liquid chromatographic (HPLC) technique. Normal tissues were demonstrated to contain higher tryptophan, cholesterol and lipid content, while bladder tumor tissues were rich in nucleic acids, collagen and carotenoids. In particular, β-carotene, one of the major types of carotenoids, was found through HPLC analysis of the extract of bladder tissues. The statistical software SPSS was applied to classify the spectra of the two types of tissues according to their differences. The sensitivity and specificity of 96.7 and 66.7% were obtained, respectively. In addition, different layers of the bladder wall including mucosa (lumps), muscle and adipose bladder tissue were analyzed by Raman mapping technique in response to previous Raman studies of bladder tissues. All of these will play an important role as a directive tool for the future diagnosis of bladder cancer in vivo.

  1. High resolution spectroscopic study of BeΛ10

    DOE PAGESBeta

    Gogami, T.; Chen, C.; Kawama, D.; Achenbach, P.; Ahmidouch, A.; Albayrak, I.; Androic, D.; Asaturyan, A.; Asaturyan, R.; Ates, O.; et al

    2016-03-10

    Spectroscopy of amore » $$^{10}_{\\Lambda}$$Be hypernucleus was carried out at JLab Hall C using the $$(e,e^{\\prime}K^{+})$$ reaction. A new magnetic spectrometer system (SPL+HES+HKS), specifically designed for high resolution hypernuclear spectroscopy, was used to obtain an energy spectrum with a resolution of 0.78 MeV (FWHM). The well-calibrated spectrometer system of the present experiment using the $$p(e,e^{\\prime}K^{+})\\Lambda,\\Sigma^{0}$$ reactions allowed us to determine the energy levels, and the binding energy of the ground state peak (mixture of 1$$^{-}$$ and 2$$^{-}$$ states) was obtained to be B$$_{\\Lambda}$$=8.55$$\\pm$$0.07(stat.)$$\\pm$$0.11(sys.) MeV. Furthermore, the result indicates that the ground state energy is shallower than that of an emulsion study by about 0.5 MeV which provides valuable experimental information on charge symmetry breaking effect in the $$\\Lambda N$$ interaction.« less

  2. Spectroscopic Studies on the Characterization of a Persian Playing Card.

    PubMed

    Holakooei, Parviz; Niknejad, Maryam; Vaccaro, Carmela

    2016-01-01

    This paper presents the results of our investigations on a playing card preserved at The Mūzih-i Āynih va Rushanāī in Yazd, Iran. Conducting micro X-ray fluorescence spectrometry (μ-XRF), micro-Raman spectroscopy (μ-Raman), infrared reflectography (IRR), ultraviolet fluorescence photography, radiography, and optical microscopy, various paints applied on the playing card were identified. According to our analytical studies, red, green, blue, black, and gold-like metallic paints were identified to be a red monoazo pigment (β-naphthol PR 53:1), chrome green, artificial ultramarine blue, carbon black, and brass powder (Dutch metal powder), respectively, dating the playing card to 1895 onward based on the manufacturing date of the red monoazo pigment. Barite was also shown to be mixed with the pigments as an extender. On the other hand, the portrait's face of the playing card was peculiarly blackened. Our analytical approach toward characterizing the blackened face showed that the black paint was achieved by carbon black and, in other words, the face was not blackened due to the darkening of Pb-bearing pigments. Moreover, it was shown that there was no underdrawing under the black face and the black paint was most probably executed in the same time with the other paints. Considering the possible use of the playing card, it was suggested not to remove the blackened face in the cleaning process since the black paint was a part of the integrity of the playing card. PMID:26767645

  3. Spectroscopic Studies of Azul Maya: Novel Organic/Inorganic Complexes

    NASA Astrophysics Data System (ADS)

    Reza, Layra; Manciu, Felicia; Torres, Brenda; Polette, Lori; Chianelli, Russell

    2006-10-01

    Maya pigments are novel organic/inorganic hybrid materials with multiple technological applications. The materials are surface compounds formed by heating an organic molecule such as indigo with an inorganic compound such as palygorskite, which is a common clay. The organic molecule upon heating forms a strong interaction with the clay surface stabilizing both entities. This strong interaction is exhibited through a color change from deep blue to the well-known Maya Blue indicating an exchange of electron density at the surface. Analysis by infrared absorption and Raman spectroscopy demonstrate the disappearance of nitrogen-hydrogen (N-H) bonding, as the indigo molecule incorporates into the inorganic palygorskite material. Infrared data confirm the loss of zeolitic water and a partial removal of structural water after the heating process. Carbon and oxygen studies at Stanford Synchrotron Radiation Laboratory by X-Ray photoemission spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS), respectively, suggest possible cationic (Al^+3) bonding of the organic molecule to palygorskite compound.

  4. Spectroscopic studies on the antioxidant activity of ellagic acid

    NASA Astrophysics Data System (ADS)

    Kilic, Ismail; Yeşiloğlu, Yeşim; Bayrak, Yüksel

    2014-09-01

    Ellagic acid (EA, C14H6O8) is a natural dietary polyphenol whose benefits in a variety of diseases shown in epidemiological and experimental studies involve anti-inflammation, anti-proliferation, anti-angiogenesis, anticarcinogenesis and anti-oxidation properties. In vitro radical scavenging and antioxidant capacity of EA were clarified using different analytical methodologies such as total antioxidant activity determination by ferric thiocyanate, hydrogen peroxide scavenging, 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH) scavenging, 2,2‧-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity and superoxide anion radical scavenging, ferrous ions (Fe2+) chelating activity and ferric ions (Fe3+) reducing ability. EA inhibited 71.2% lipid peroxidation of a linoleic acid emulsion at 45 μg/mL concentration. On the other hand, butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), α-tocopherol and ascorbic acid displayed 69.8%, 66.8%, 64.5% and 59.7% inhibition on the peroxidation of linoleic acid emulsion at the same concentration, respectively. In addition, EA had an effective DPPH• scavenging, ABTSrad + scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, ferric ions (Fe3+) reducing power and ferrous ions (Fe2+) chelating activities. Also, those various antioxidant activities were compared to BHA, BHT, α-tocopherol and ascorbic acid as references antioxidant compounds. These results suggested that EA can be used in the pharmacological, food industry and medicine because of these properties.

  5. Reduction of selenite on iron surfaces: Amicro-spectroscopic study

    NASA Astrophysics Data System (ADS)

    Scheidegger, A. M.; Grolimund, D.; Cui, D.; Devoy, J.; Spahiu, K.; Wersin, P.; Bonhoure, I.; Janousch, M.

    2003-03-01

    Under anoxie conditions zero-valent iron can react with water to produce hydrogen gas and magnetite or green rust, a highly reactive mineral phase that can induce reduction processes and thus control the speciation, the solubility, toxicity and the mobility of redox sensitive elements in (nuclear) waste repositories. In this study micro X-ray fluorescence (micro-XRF) and micro X-ray absorption spectroscopy (micro-XAS) were used to investigate the speciation of selenium that immobilized in the presence of Fe(0) and an anoxie synthetic groundwater solution. The selenium immobilization was accompanied by the formation of a green rust corrosion layer. Micro-XRF revealed that a Se-rich layer is present along the iron surfaces that were exposed to the Se(IV) solution. Micro-XAS experiments at the Se K-edge showed that Se(IV) was reduced to elemental Se(0). Thus, the reactivity of zero-valent and green rust should to be considered in assessing the long-term fate of selenium in nuclear waste repositories.

  6. Synthesis, growth and vibrational spectroscopic study of a novel coumarinoylthiazole.

    PubMed

    Reshmy, R; Sajan, D; Kurien Thomas, K; Sulekha, A; Rajasekharan, K N; Selvanayagam, S; Alver, O

    2012-11-01

    An efficient route was developed for the synthesis of novel 3-(2-morpholinyl-4-phenylthiazol-5-oyl)coumarin (MPTC). FT-IR spectrum of MPTC was recorded and analyzed. The crystal structure data are also described. The vibrational wavenumbers were computed theoretically using the Gaussian03 package of programs using HF/6-31G(d) and B3LYP/6-31G(d) levels of theory. The data obtained from vibrational wave number calculations are used to assign vibrational bands observed in the infrared spectra of MPTC. The first hyperpolarizability, infrared absorption band intensities and intensities of raman active bands are reported. The calculated first hyperpolarizability is comparable with the values reported for compounds of similar structure. The structural parameters of MPTC obtained from XRD studies are in agreement with the calculated values. The unit cell parameters of crystals of MPTC are: a=8.6017(10)Å, b=9.9735(5)Å, c=13.3870(13)Å, α=111.123(6)°, β=90.102(9)°, γ=110.246(6)°, and Z=2,1.397 Mg/m(3). PMID:22940047

  7. Vibrational spectroscopic study of hydroxylpyromorphite-hydroxylmimetite solid solutions

    NASA Astrophysics Data System (ADS)

    Kwaśniak-Kominek, Monika; Matusik, Jakub; Bajda, Tomasz; Manecki, Maciej

    2013-04-01

    Hydroxylpyromorphite Pb5(PO4)3OH and hydroxylmimetite Pb5(AsO4)3OH minerals belong to the apatite supergroup. Their structure allows isomorphous substitutions in both cationic and anionic positions. They are isostructural with pyromorphite Pb5(PO4)3Cl and mimetite Pb5(AsO4)3OH which are the end products of in situ phosphate induced remediation of soils polluted with heavy metals e.g. lead. The research objective was to synthesize and characterize the members of above mentioned solid solution. The minerals were synthesized at room temperature and analyzed by X-Ray diffraction and Infrared spectroscopy (FTIR-DRIFT). The product syntheses was crystalline phase without any impurities within the detection limit of XRD. Shifts of certain diffraction peaks were observed in solid solution series due to replacement PO4 after AsO4. The bands v3 and v4 attributed to vibrations in the PO4 and AsO4 tetrahedra appear at 1050-790 and 580-534 cm-1. Due to difference in atomic mass of P and As as well as bonding strength of P-O and As-O the skeletal bands shift to lower wavenumbers with the increase of AsO4 substitution. The correlation between the position of vibrational modes and the chemical composition is observed. The OH stretching mode in the FTIR spectra appears in the range of 3765-3552 cm-1 as a sharp band for the end members of the solid solution. For the intermediate minerals the OH band becomes complex. The analysis of deconvoluted OH bands indicated several vibrational modes which suggested a significant change of OH group local environment induced by substitutions. The study was supported by the AGH University of Science and Technology (Krakow, Poland) as the research project No. 307 473 638.

  8. Synchronous fluorescence spectroscopic study of solvatochromic curcumin dye

    NASA Astrophysics Data System (ADS)

    Patra, Digambara; Barakat, Christelle

    2011-09-01

    Curcumin, the main yellow bioactive component of turmeric, has recently acquired attention by chemists due its wide range of potential biological applications as an antioxidant, an anti-inflammatory, and an anti-carcinogenic agent. This molecule fluoresces weakly and poorly soluble in water. In this detailed study of curcumin in thirteen different solvents, both the absorption and fluorescence spectra of curcumin was found to be broad, however, a narrower and simple synchronous fluorescence spectrum of curcumin was obtained at Δ λ = 10-20 nm. Lippert-Mataga plot of curcumin in different solvents illustrated two sets of linearity which is consistent with the plot of Stokes' shift vs. the ET30. When Stokes's shift in wavenumber scale was replaced by synchronous fluorescence maximum in nanometer scale, the solvent polarity dependency measured by λSFSmax vs. Lippert-Mataga plot or ET30 values offered similar trends as measured via Stokes' shift for protic and aprotic solvents for curcumin. Better linear correlation of λSFSmax vs. π* scale of solvent polarity was found compared to λabsmax or λemmax or Stokes' shift measurements. In Stokes' shift measurement both absorption/excitation as well as emission (fluorescence) spectra are required to compute the Stokes' shift in wavenumber scale, but measurement could be done in a very fast and simple way by taking a single scan of SFS avoiding calculation and obtain information about polarity of the solvent. Curcumin decay properties in all the solvents could be fitted well to a double-exponential decay function.

  9. Impedance and electric modulus study of amorphous TiTaO thin films: highlight of the interphase effect

    NASA Astrophysics Data System (ADS)

    Rouahi, A.; Kahouli, A.; Challali, F.; Besland, M. P.; Vallée, C.; Yangui, B.; Salimy, S.; Goullet, A.; Sylvestre, A.

    2013-02-01

    The influence of phases and phase's boundaries of TiO2 and Ta2O5 in the dielectric and electric response of TiTaO (100 nm thick) elaborated by RF magnetron sputtering was highlighted by complex impedance spectroscopy. Dielectric and electric modulus properties were studied over a wide frequency range (0.1-105 Hz) and at various temperatures (-160 to 120 °C). The diagram of Argand (ɛ″ versus ɛ‧) shows the contribution of phases, phases' boundaries and conductivity effect on the electric response of TiTaO thin films. Moreover, the resistance of the material decreases when the temperature increases, thus the material exhibits a negative temperature coefficient of resistance. The electric modulus plot indicates the presence of two peaks of relaxation. The first relaxation process appears at low temperature with activation energy of about 0.22 eV and it is related to the first ionization energy of oxygen vacancies. The second relaxation process appears at high temperature with activation energy of about 0.44 eV. This second peak is attributed to the Maxwell-Wagner-Sillars relaxation. The plots of the complex dielectric modulus and the impedance as a function of frequency allow concluding to a localized relaxation due to the long-range conductivity in the TiTaO film.

  10. Spectroscopic studies of molybdenum complexes as models for nitrogenase

    SciTech Connect

    Walker, T.P.

    1981-05-01

    Because biological nitrogen fixation requires Mo, there is an interest in inorganic Mo complexes which mimic the reactions of nitrogen-fixing enzymes. Two such complexes are the dimer Mo/sub 2/O/sub 4/ (cysteine)/sub 2//sup 2 -/ and trans-Mo(N/sub 2/)/sub 2/(dppe)/sub 2/ (dppe = 1,2-bis(diphenylphosphino)ethane). The H/sup 1/ and C/sup 13/ NMR of solutions of Mo/sub 2/O/sub 4/(cys)/sub 2//sup 2 -/ are described. It is shown that in aqueous solution the cysteine ligands assume at least three distinct configurations. A step-wise dissociation of the cysteine ligand is proposed to explain the data. The Extended X-ray Absorption Fine Structure (EXAFS) of trans-Mo(N/sub 2/)/sub 2/(dppe)/sub 2/ is described and compared to the EXAFS of MoH/sub 4/(dppe)/sub 2/. The spectra are fitted to amplitude and phase parameters developed at Bell Laboratories. On the basis of this analysis, one can determine (1) that the dinitrogen complex contains nitrogen and the hydride complex does not and (2) the correct Mo-N distance. This is significant because the Mo inn both complexes is coordinated by four P atoms which dominate the EXAFS. A similar sort of interference is present in nitrogenase due to S coordination of the Mo in the enzyme. This model experiment indicates that, given adequate signal to noise ratios, the presence or absence of dinitrogen coordination to Mo in the enzyme may be determined by EXAFS using existing data analysis techniques. A new reaction between Mo/sub 2/O/sub 4/(cys)/sub 2//sup 2 -/ and acetylene is described to the extent it is presently understood. A strong EPR signal is observed, suggesting the production of stable Mo(V) monomers. EXAFS studies support this suggestion. The Mo K-edge is described. The edge data suggests Mo(VI) is also produced in the reaction. Ultraviolet spectra suggest that cysteine is released in the course of the reaction.

  11. Spectroscopic studies of Synechococcus sp PCC 7002 phycobilisome core mutants

    SciTech Connect

    Gindt, Y.M.

    1993-04-01

    The role of the L{sub cm} (I), {beta}{sup 18} (II), and {alpha}{sup AP-B} (III) chromoproteins in the phycobilisome (PBS) core was investigated using genetically engineered strains of Synechococcus missing different polypeptides. Intact cells, isolated PBS, and subcore preparations for each mutant were studied to determine the effect of that mutation on energy transfer within the PBS core and to the reaction centers. Three mutants lacked the II and/or III polypeptides, while the I chromophore was altered in others. A lower energy absorbing chromophore, A{sub max} = 695 nm, was substituted for the I chromophore. The deletion of the II and III subunits had no discernible effect on energy transfer from the PBS to PSII. In cells and isolated PBS, the altered I chromophore acts to quench the PBS complex and to redirect the energy which would be transferred to PSII. In the PBS and subcore preparations, deletion of the III subunit did not alter energy transfer within the core. The deletion of the II subunit from the PBS caused a small decrease in the excited state lifetimes of the final emitters indicating more disorder within the core. The I chromophore was found to absorb at 670nm and to emit at 683nm within the intact PBS. The II chromophore emits at 679nm while the III chromophore emits at 682nm. A strong interaction exists between the I chromophore and the II subunit. Upon deletion of the II subunit from the PBS core, the I chromophore emits at a higher energy. The II subunit could act to stabilize the I chromophore-binding pocket, or exciton coupling could be occurring between the two. The role of the III chromophore is still unclear at this time. The III chromophore does contribute to the RT emission of the isolated PBS, but it transfers energy to I at 77 K. One can conclude that the III subunit is adjacent to the trimer containing the I polypeptide.

  12. Spectroscopic studies of Synechococcus sp PCC 7002 phycobilisome core mutants

    SciTech Connect

    Gindt, Y.M.

    1993-04-01

    The role of the L[sub cm] (I), [beta][sup 18] (II), and [alpha][sup AP-B] (III) chromoproteins in the phycobilisome (PBS) core was investigated using genetically engineered strains of Synechococcus missing different polypeptides. Intact cells, isolated PBS, and subcore preparations for each mutant were studied to determine the effect of that mutation on energy transfer within the PBS core and to the reaction centers. Three mutants lacked the II and/or III polypeptides, while the I chromophore was altered in others. A lower energy absorbing chromophore, A[sub max] = 695 nm, was substituted for the I chromophore. The deletion of the II and III subunits had no discernible effect on energy transfer from the PBS to PSII. In cells and isolated PBS, the altered I chromophore acts to quench the PBS complex and to redirect the energy which would be transferred to PSII. In the PBS and subcore preparations, deletion of the III subunit did not alter energy transfer within the core. The deletion of the II subunit from the PBS caused a small decrease in the excited state lifetimes of the final emitters indicating more disorder within the core. The I chromophore was found to absorb at 670nm and to emit at 683nm within the intact PBS. The II chromophore emits at 679nm while the III chromophore emits at 682nm. A strong interaction exists between the I chromophore and the II subunit. Upon deletion of the II subunit from the PBS core, the I chromophore emits at a higher energy. The II subunit could act to stabilize the I chromophore-binding pocket, or exciton coupling could be occurring between the two. The role of the III chromophore is still unclear at this time. The III chromophore does contribute to the RT emission of the isolated PBS, but it transfers energy to I at 77 K. One can conclude that the III subunit is adjacent to the trimer containing the I polypeptide.

  13. A spectroscopic and dynamical study of binary and other Cepheids

    NASA Astrophysics Data System (ADS)

    Petterson, Orlon King Lee

    High resolution observations have been made of a number of southern Cepheids to make an observational and theoretical study of Cepheid variables using radial velocities. The stars studied were part of a long term programme to observe southern variable stars, from which a valuable database of radial velocities gathered over a long period were available. Sixteen échelle spectrograph orders in the wavelength region 5400 - 8600Å were used, which included a number of absorption lines covering a range of species and excitation potentials. The line bisector technique was used to measure stellar and telluric lines and to obtain radial velocities. To improve the precision of the radial velocities we used telluric lines to calibrate the observations to a common reference frame. The radial velocities have a precision of ~300ms-1 allowing the detection of velocity differences of ~1 kms-1 with confidence. The radial velocity data obtained at Mount John University Observatory (MJUO) was combined with data from various sources to determine the orbits of any Cepheids exhibiting orbital motion. The various orbital parameters were determined for a number of systems and where radial velocities for the companions exist, some estimate of the mass was made. The precision of the radial velocities obtained from MJUO also allowed us to search for line level effects for a number of species among the Cepheid spectra. A number of IAU standard stars were observed to calibrate the radial velocities obtained at MJUO to the IAU standard scale. The radial velocities from MJUO were found not to differ significantly from the IAU values. Binary Cepheids are particularly useful in the determination of Cepheid masses, which are still an active topic for astronomical research. The value of the MJUO data was that it provided a consistent set of data against which other sources of data could be compared. For 8 of the Cepheids new or improved orbital solutions were found. They are Y Car, YZ Car, AX Cir

  14. ADVANCES IN IMPEDANCE THEORY

    SciTech Connect

    Stupakov, G.; /SLAC

    2009-06-05

    We review recent progress in the following areas of the impedance theory: calculation of impedance of tapers and small angle collimators; optical approximation and parabolic equation for the high-frequency impedance; impedance due to resistive inserts in a perfectly conducting pipe.

  15. Spectroscopic study of some diatomic molecules via the proper quantization rule

    NASA Astrophysics Data System (ADS)

    Falaye, B.

    Spectroscopic techniques are very essential tools in studying electronic structures, spectroscopic constants and energetic properties of diatomic molecules. These techniques are also required for parametrization of new method based on theoretical analysis and computational calculations. In this research, we apply the proper quantization rule in spectroscopic study of some diatomic molecules by solving the Schrödinger equation with two solvable quantum molecular systems-Tietz-Wei and shifted Deng-Fan potential models for their approximate nonrelativistic energy states via an appropriate approximation to the centrifugal term. We show that the energy levels can be determined from its ground state energy. The beauty and simplicity of the method applied in this study is that, it can be applied to any exactly as well as approximately solvable models. The validity and accuracy of the method is tested with previous techniques via numerical computation for H2 and CO diatomic molecules. The result also include energy spectrum of 5 different electronic states of NO and 2 different electronic state of ICl.

  16. Theoretical study and experimental verification on calculation of bearing capacity of aerostatic restrictor system with a gas-impedance model

    NASA Astrophysics Data System (ADS)

    Cheng, Yang; Li, Dongsheng; Hu, Jiacheng; Li, Jiafu

    2015-02-01

    Bearing capacity is a most significant parameter to evaluate the quality of aerostatic restrictor system. A gas-impedance model was established using the theory of gas dynamics to determine the bearing capacity of three aerostatic restrictor systems which were multi-micro channel, dual U-shaped and dual circle-shaped aerostatic restrictor system respectively. Experiments were run using gas-impedance method and finite difference method to prove the validity of gas-impedance method. Experimental results indicated the gas-impedance model method was effective in establishing the bearing capacity of aerostatic restrictor system.

  17. Impedance analysis of acupuncture points and pathways

    NASA Astrophysics Data System (ADS)

    Teplan, Michal; Kukučka, Marek; Ondrejkovičová, Alena

    2011-12-01

    Investigation of impedance characteristics of acupuncture points from acoustic to radio frequency range is addressed. Discernment and localization of acupuncture points in initial single subject study was unsuccessfully attempted by impedance map technique. Vector impedance analyses determined possible resonant zones in MHz region.

  18. Experimental and theoretical spectroscopic studies of dye modification in synthetic Maya Blue pigment

    NASA Astrophysics Data System (ADS)

    Reza, Layra; Manciu, Felicia; Ramirez, Alejandra; Chianelli, Russell

    2009-03-01

    Maya pigments are hybrid organic/inorganic materials with multiple technology applications that possess unprecedented stability with respect to harsh environment conditions. In this investigation, we address the question of how the organic indigo dye modifies as it binds to the inorganic palygorskite clay to form a pigment similar to Maya Blue after a heating treatment is applied. Both infrared and Raman spectroscopic data demonstrate the disappearance of nitrogen-hydrogen (N-H) bonding, as the indigo molecule incorporates into the inorganic palygorskite material. This effect suggests a transformation of the dye from indigo to dehydroindigo. Furthermore, the Raman and infrared absorption results demonstrate partial elimination of the selection rules for the centrosymmetric indigo, which provides further evidence for this conversion. Theoretical spectroscopic studies are also addressed in this investigation to confirm the transformation of the dye into dehydroindigo.

  19. Exploring binding properties of sertraline with human serum albumin: Combination of spectroscopic and molecular modeling studies.

    PubMed

    Shahlaei, Mohsen; Rahimi, Behnoosh; Nowroozi, Amin; Ashrafi-Kooshk, Mohammad Reza; Sadrjavadi, Komail; Khodarahmi, Reza

    2015-12-01

    Human serum albumin (HSA)-drug binding is an important factor to determine half life and bioavailability of drugs. In the present research, the interaction of sertraline (SER) to HSA was investigated using combination of spectroscopic and molecular modeling techniques. Changes in the UV-Vis, CD and FT-IR spectra as well as a significant degree of tryptophan fluorescence quenching were observed upon SER-HSA interaction. Data obtained by spectroscopic methods along with the computational studies suggest that SER binds to residues located in subdomain IIA of HSA. Analysis of spectroscopic data represented the formation of 1:1 complex, significant binding affinity, negative values of entropy and enthalpy changes and the essential role of hydrophobic interactions in binding of SER to HSA. The binding models were demonstrated in the aspects of SER's conformation, active site interactions, important amino acids and hydrogen bonding. Computational mapping of the possible binding site of SER confirmed that the ligand to be bound in a large hydrophobic cavity of HSA. In accordance with experimental data, computational analyses indicated that SER binding does not alter the secondary structure of the protein. The results not only lead to a better understanding of interaction between SER and HSA but also provide useful data about the influence of SER on the protein conformation. PMID:26471709

  20. A photoelectron spectroscopic and computational study of the o-dicarbadodecaborane parent anion

    NASA Astrophysics Data System (ADS)

    Zhang, Xinxing; Bowen, Kit

    2016-06-01

    We report a combined photoelectron spectroscopic and computational study of the o-dicarbadodecaborane (o-carborane) parent anion, (C2B10H12)-. Previous studies that focused on the electrophilic nature of o-carborane led to tantalizing yet mixed results. In our study, we confirmed that o-carborane does in fact form a parent anion and that it has considerable stability. This anion is an isomer ("Anion iso 2") where unlike in neutral o-carborane, the two carbon atoms are not bound.

  1. A photoelectron spectroscopic and computational study of the o-dicarbadodecaborane parent anion.

    PubMed

    Zhang, Xinxing; Bowen, Kit

    2016-06-14

    We report a combined photoelectron spectroscopic and computational study of the o-dicarbadodecaborane (o-carborane) parent anion, (C2B10H12)(-). Previous studies that focused on the electrophilic nature of o-carborane led to tantalizing yet mixed results. In our study, we confirmed that o-carborane does in fact form a parent anion and that it has considerable stability. This anion is an isomer ("Anion iso 2") where unlike in neutral o-carborane, the two carbon atoms are not bound. PMID:27306011

  2. Study of caffeine as corrosion inhibitors of carbon steel in chloride solution containing hydrogen sulfide using electrochemical impedance spectroscopy (EIS)

    NASA Astrophysics Data System (ADS)

    Solehudin, Agus; Berman, Ega Taqwali; Nurdin, Isdiriayani

    2015-09-01

    The corrosion behaviour of steel surface in the absence and presence of caffeine in 3.5% NaCl solution containing dissolved H2S gas is studied using electrochemical impedance spectroscopy (EIS). The experimental results of carbon steel corrosion in 3.5% NaCl solution containing 500 mg/l H2S at different caffeine concentrations showed that corrosion rate of carbon steel decreases with increasing of caffeine concentrations from 0 to 0,1 mmol/l. Whereas, the corrosion rate increase with increasing of caffeine concentrations from 1 to 10 mmol/l. It is clear that no inhibition efficiency increases with increasing inhibitor concentration. The optimum value of inhibition efficiency was 90% at a caffeine concentration of 0.1 mmol/l. This suggests that caffeine's performance as a corrosion inhibitor is more effective at a concentration of 0.1 mmol/l.

  3. Dopant effects on 2-ethyl-1-hexanol: A dual-channel impedance spectroscopy and neutron scattering study

    SciTech Connect

    Singh, Lokendra P.; Richert, Ranko; Raihane, Ahmed; Alba-Simionesco, Christiane

    2015-01-07

    A two-channel impedance technique has been used to study the relaxation behavior of 2-ethyl-1-hexanol with polar and non-polar dopants at the few percent concentration level over a wide temperature and frequency range. The non-polar dopants shift both the Debye and the primary structural relaxation time in the same direction, to shorter times for 3-methylpentane and to longer times for squalane, consistent with the relative glass transition temperatures (T{sub g}) of the components. By contrast, polar dopants such as water or methanol modify the α-process towards slower dynamics and increased amplitude, while the Debye process is accelerated and with a decreased amplitude. This effect of adding water to alcohol is explained by water promoting more compact structures with reduced Kirkwood correlation factors. This picture is consistent with a shift in the neutron scattering pre-peak to lower scattering vectors and with simulation work on alcohol-water systems.

  4. Corrosion protection of copper by polypyrrole film studied by electrochemical impedance spectroscopy and the electrochemical quartz microbalance

    NASA Astrophysics Data System (ADS)

    Lei, Yanhua; Ohtsuka, Toshiaki; Sheng, Nan

    2015-12-01

    Polypyrrole (PPy) films were synthesized on copper in solution of sodium di-hydrogen phosphate and phytate for corrosion protection. The protection properties of PPy films were comparatively investigated in NaCl solution. During two months immersion, the PPy film doped with phytate anions, working as a cationic perm-selective membrane, inhibited the dissolution of copper to 1% of bare copper. Differently, the PPy film doped with di-hydrogen phosphate anions, possessing anionic perm-selectivity, was gradually reduced, and inhibited the dissolution to 7.8% of bare copper. Degradation of the PPy films was studied by comparing the electrochemical impedance spectroscopy change at different immersion time and Raman spectra change after immersion.

  5. Dopant effects on 2-ethyl-1-hexanol: A dual-channel impedance spectroscopy and neutron scattering study

    NASA Astrophysics Data System (ADS)

    Singh, Lokendra P.; Raihane, Ahmed; Alba-Simionesco, Christiane; Richert, Ranko

    2015-01-01

    A two-channel impedance technique has been used to study the relaxation behavior of 2-ethyl-1-hexanol with polar and non-polar dopants at the few percent concentration level over a wide temperature and frequency range. The non-polar dopants shift both the Debye and the primary structural relaxation time in the same direction, to shorter times for 3-methylpentane and to longer times for squalane, consistent with the relative glass transition temperatures (Tg) of the components. By contrast, polar dopants such as water or methanol modify the α-process towards slower dynamics and increased amplitude, while the Debye process is accelerated and with a decreased amplitude. This effect of adding water to alcohol is explained by water promoting more compact structures with reduced Kirkwood correlation factors. This picture is consistent with a shift in the neutron scattering pre-peak to lower scattering vectors and with simulation work on alcohol-water systems.

  6. Joint Impedance Decreases during Movement Initiation

    PubMed Central

    Ludvig, Daniel; Antos, Stephen A.; Perreault, Eric J.

    2013-01-01

    The mechanical properties of the joint influence how we interact with our environment and hence are important in the control of both posture and movement. Many studies have investigated how the mechanical properties—specifically the impedance—of different joints vary with different postural tasks. However, studies on how joint impedance varies with movement remain limited. The few studies that have investigated how impedance varies with movement have found that impedance is lower during movement than during posture. In this study we investigated how impedance changed as people transitioned from a postural task to a movement task. We found that subjects’ joint impedances decreased at the initiation of movement, prior to increasing at the cessation of movement. This decrease in impedance occurred even though the subjects’ torque and EMG levels increased. These findings suggest that during movement the central nervous system may control joint impedance independently of muscle activation. PMID:23366632

  7. Spectroscopic study of sub-barrier quasi-elastic nuclear reactions

    SciTech Connect

    Pass, C.N.; Evans, P.M.; Smith, A.E.; Stuttge, L.; Betts, R.R.; Lilley, J.S.; Connell, K.A.; Simpson, J.; Smith, J.R.; James, A.N.

    1988-01-01

    The technique developed in this paper is particularly well suited to the detailed spectroscopic study of low energy quasi-elastic nuclear reactions and by overcoming the limitations of conventional procedure, the prospect of detailed studies of inclusive reaction mechanism may be realised. With only limited statistics we find evidence for strong multistep character in the transfer of a single nucleon from spherical vibrational target to spherical projectile nuclei. The suggestive measurements reported here may be made definitive through extended runs based on this technique and experiments planned for the future offer the real prospect of developing a quantified interpretation of the reaction process. 9 refs. 5 figs.

  8. Impedance spectroscopy study with Ca(UO{sub 2}PO{sub 4}){sub 2}10.5H{sub 2}O films

    SciTech Connect

    Ramos-Barrado, J.R.; Benavente, J.; Bruque, S.; Martinez, M.

    1995-03-15

    Calcium uranyl phosphate (CaUP) films were prepared and characterized both chemically and structurally. The electrical behavior of the films, as a solid phase (dry film) and in contact with aqueous solutions of electrolytes containing the generating ions (wet film), was studied by impedance spectroscopy. These last measurements made it possible to determine the contribution of both the bulk film and film/electrolyte interface. For both dry and wet films, the equivalent circuits are a parallel combination of resistance and a nonideal capacitor. Temperature dependence of the impedance of the CAUP solid films was considered, while concentration dependence of the film resistance when it is in contact with the electrolyte solutions was determined. In this case, the contribution of both the bulk film and electrolyte/film interface to the total impedance was also studied.

  9. Impedance studies of nickel/cadmium and nickel/hydrogen cells using the cell case as a reference electrode

    NASA Technical Reports Server (NTRS)

    Reid, Margaret A.

    1990-01-01

    Impedance measurements have been made on several Ni/Cd and Ni/H2 flight-weight cells using the case as a reference electrode. For these measurements, the voltage of the case with respect to the anode or cathode is unimportant provided that it remains stable during the measurement of the impedance. In the cells measured so far, the voltage of the cell cases with respect to the individual electrodes differ from cell to cell, even at the same overall cell voltage, but they remain stable with time. The measurements can thus be used to separate the cell impedance into the contributions of each electrode, allowing improved diagnosis of cell problems.

  10. A Spectroscopic Study of Hydra I: The Possible Progenitor of the Eastern Banded Structure

    NASA Astrophysics Data System (ADS)

    Kimmig, Brian; Hargis, Jonathan R.; Willman, Beth; Caldwell, Nelson; Strader, Jay; Walker, Matthew G.

    2015-01-01

    We present initial results of an MMT/Hectochelle spectroscopic study of the Hydra I spatial overdensity located along the Eastern Banded Structure (EBS) stellar stream. The extended double-lobed structure and strength of the overdensity suggest that Hydra I may be the stream's progenitor and undergoing active disruption. With its distance of only ~10 kpc, Hydra I presents a unique opportunity to study the disruption of a star cluster or dwarf galaxy. In past work, SDSS/SEGUE velocities revealed Hydra I to be a kinematically cold structure. However, the small number of candidate members and the significant SEGUE velocity uncertainties (~10 - 15 km/s) precludes testing the nature of Hydra I. To better understand its chemo-dynamic properties, we have begun a spectroscopic survey of the Hydra I/EBS region in order to (i) obtain a robust, velocity-based selection of candidate member stars, (ii) use precise velocities to measure the velocity dispersion, (iii) study the spatial distribution of spectroscopic members, and (iv) measure its proper motion. At present, we have surveyed a ~3 deg x ~3 deg region, which encompasses the entire ~4 sq. deg spatial extent of Hydra I. We have obtained a total of 1354 spectra in this region, with RV uncertainties smaller than ~5 km/s at magnitudes brighter than g~21.6. This work presents our confirmation of Hydra I as a cold halo structure, as well as a more detailed analysis of the membership and spatial/velocity structure of Hydra I.

  11. Synthesis, spectroscopic characterizations, crystal structures and DFT studies of nalidixic acid carbonyl hydrazones derivatives

    NASA Astrophysics Data System (ADS)

    Bergamini, F. R. G.; Ribeiro, M. A.; Lancellotti, M.; Machado, D.; Miranda, P. C. M. L.; Cuin, A.; Formiga, A. L. B.; Corbi, P. P.

    2016-09-01

    This article describes the synthesis and characterization of the 1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carbohydrazide (hzd) and six carbonyl hydrazones derivatives of the nalidixic with 1H-pyrrol-2-ylmethylidene (hpyrr), 1H-imidazol-2-ylmethylidene (h2imi), pyridin-2-ylmethylidene (h2py), pyridin-3-ylmethylidene (h3py), pyridin-4-ylmethylidene(h4py) and (2-hydroxyphenyl)methylidene (hsali). The carbonyl hydrazones were characterized by elemental and ESI-QTOF-MS analyses, IR and detailed NMR spectroscopic measurements. The 2D NMR experiments allowed the unambiguous assignment of the hydrogen, carbon and nitrogen atoms, which have not been reported for nalidixic acid carbonyl hydrazone derivatives so far. Crystal structures of hzd and the new carbonyl hydrazones h2imi, hpyrr and h3py were determined by X-ray diffraction studies. Although the synthesis of hzd was reported decades ago, the hzd crystal structure have not been reported yet. Geometric optimizations of all the characterized structures were performed with the aid of DFT studies. Despite the fact that the hydrazones with 2-pyridine carboxylic acid (h2py) and salicyl aldehyde (hsali) were already reported by literature, a detailed spectroscopic study followed by DFT studies are also reported for such compounds in this manuscript. Antimicrobial studies of the compounds are also presented.

  12. Quantitative carbon-13 nuclear magnetic resonance spectroscopic study of mobile residues in bacteriorhodopsin

    SciTech Connect

    Bowers, J.L.; Oldfield, E.

    1988-07-12

    The authors have used quantitative carbon-13 nuclear magnetic resonance (NMR) spectroscopy to study the dynamic structure of the backbone of bacteriorhodopsin in the purple membrane of Halobacterium halobium R/sub 1/ and JW-3. NMR experiments were performed using an internal sucrose quantitation standard on purple membranes in which one of the following /sup 13/C'-labeled amino acids had been biosynthetically incorporated: glycine, isoleucine, lysine, phenylalanine, and valine. The results suggest that the C-terminus of the polypeptide chain backbone, and possibly one of the connecting loops, undergoes rapid, large angle fluctuations. The results are compared with previous NMR and fluorescence spectroscopic data obtained on bacteriorhodopsin.

  13. Thermal Physical, and Infrared Spectroscopic Studies on Glasses Prepared by Microwave Route

    SciTech Connect

    Jagadeesha, N.; Gowda, V. C. Veeranna; Chakradhar, R. P. S.; Reddy, C. Narayana

    2011-07-15

    This paper describes thermal, physical and spectroscopic properties of glasses prepared by a novel micro wave method. These studies exhibited a strong compositional dependent trend and existence of characteristic boro-vanadate groups in these glasses. The scheme of modification of borate and vanadate groups is controlled by Sanderson's electronegativity principle. Analysis of density and glass transition temperatures suggests the presence of characteristic four coordinated borate and diboro - vanadate groups in these glasses. The presence of [BO{sub 4/2}]{sup -} and [B{sub 2}V{sub 2}O{sub 9}]{sup 2-}) groups are confirmed by Infrared Spectroscopy of investigated glasses.

  14. Coupling impedance for modern accelerators

    SciTech Connect

    Heifets, S.A.; Kheifets, S.A. )

    1992-03-10

    A systematic review of theoretical results for the longitudinal and transverse impedances obtained by different methods is presented. The paper comprises definitions, general theorems, modal analysis, a diffraction model, and analytical results. Several new results are included. In particular, necessary and sufficient conditions are given for the independence of the impedance from the beam longitudinal direction. The impedances of two basic simple structures---that of a {ital cavity} and that of a {ital step}---are studied in detail. The transition from the regime of a cavity to the regime of a step is explained, an approximate formula describing this transition is given, and the criterion for determining the applicability of each regime is established. The asymptotic behavior of the impedance for a finite number {ital M} of periodically arranged cavities as a function of {ital M} is studied. The different behaviors of the impedance for a single cavity and that for an infinite number of cavities are explained as resulting from the interference of the diffracted waves. A criterion for determining the transition in the impedance behavior from small {ital M} to large {ital M} is presented.

  15. Binding of copper to lysozyme: Spectroscopic, isothermal titration calorimetry and molecular docking studies

    NASA Astrophysics Data System (ADS)

    Jing, Mingyang; Song, Wei; Liu, Rutao

    2016-07-01

    Although copper is essential to all living organisms, its potential toxicity to human health have aroused wide concerns. Previous studies have reported copper could alter physical properties of lysozyme. The direct binding of copper with lysozyme might induce the conformational and functional changes of lysozyme and then influence the body's resistance to bacterial attack. To better understand the potential toxicity and toxic mechanisms of copper, the interaction of copper with lysozyme was investigated by biophysical methods including multi-spectroscopic measurements, isothermal titration calorimetry (ITC), molecular docking study and enzyme activity assay. Multi-spectroscopic measurements proved that copper quenched the intrinsic fluorescence of lysozyme in a static process accompanied by complex formation and conformational changes. The ITC results indicated that the binding interaction was a spontaneous process with approximately three thermodynamical binding sites at 298 K and the hydrophobic force is the predominant driven force. The enzyme activity was obviously inhibited by the addition of copper with catalytic residues Glu 35 and Asp 52 locating at the binding sites. This study helps to elucidate the molecular mechanism of the interaction between copper and lysozyme and provides reference for toxicological studies of copper.

  16. Binding of copper to lysozyme: Spectroscopic, isothermal titration calorimetry and molecular docking studies.

    PubMed

    Jing, Mingyang; Song, Wei; Liu, Rutao

    2016-07-01

    Although copper is essential to all living organisms, its potential toxicity to human health have aroused wide concerns. Previous studies have reported copper could alter physical properties of lysozyme. The direct binding of copper with lysozyme might induce the conformational and functional changes of lysozyme and then influence the body's resistance to bacterial attack. To better understand the potential toxicity and toxic mechanisms of copper, the interaction of copper with lysozyme was investigated by biophysical methods including multi-spectroscopic measurements, isothermal titration calorimetry (ITC), molecular docking study and enzyme activity assay. Multi-spectroscopic measurements proved that copper quenched the intrinsic fluorescence of lysozyme in a static process accompanied by complex formation and conformational changes. The ITC results indicated that the binding interaction was a spontaneous process with approximately three thermodynamical binding sites at 298K and the hydrophobic force is the predominant driven force. The enzyme activity was obviously inhibited by the addition of copper with catalytic residues Glu 35 and Asp 52 locating at the binding sites. This study helps to elucidate the molecular mechanism of the interaction between copper and lysozyme and provides reference for toxicological studies of copper. PMID:27089183

  17. Spectroscopic studies on chemical- and photo-responsive molecular machines and their bio-applications

    NASA Astrophysics Data System (ADS)

    Lau, Yuen Agnes

    2011-07-01

    The four chapters presented in this dissertation describe how various spectroscopic techniques are used: 1) to study the operation of molecular machines in solution, 2) to track the operation of molecular machines inside a single cell, and 3) to investigate the photo-decomposition pathway of a biological chromophore. Recent advances in nanotechnology have enriched the development of nano-scale molecular assemblies to be used as delivery platforms for biologically relevant molecules. Among all the molecular assemblies, molecular machines that are incorporated onto various domains of mesoporous silica nanoparticles (MSN) hold considerable potential as a reliable delivery system. Because the ease of functionalization enables chemical or photo-responsive molecular moieties to be covalently attached to the silica framework, these molecular assemblies, with defined mechanized properties, can perform specific functions under external stimuli (pH, redox, or light). While the primary function of these molecular machines is to deliver stored cargo molecules, the means of activation and the motif in which they operate are different. In the first and second chapters of this dissertation, two types of molecular machines, nanovalves and nanoimpellers, and their operations are studied. The ability to continuously monitor and image progression of molecular-based biological events in real-time can enhance our understanding of intracellular processes upon drug, protein and nucleic acid delivery. Using the photo-activated nanoimpeller described in the second chapter, the third chapter explores how it can be used to transport a nuclear staining agent, PI, inside a single cell. Nanoimpellers are made by functionalizing azobenzene molecules to the internal pore surface of MSN. The continuous cis/trans isomerizations are set in motion upon laser illumination at optimal wavelength(s), which facilitate cargo molecules to be expelled from the pores to the surrounding medium. By refining a

  18. Spectroscopic and structural study of the newly synthesized heteroligand complex of copper with creatinine and urea

    NASA Astrophysics Data System (ADS)

    Gangopadhyay, Debraj; Singh, Sachin Kumar; Sharma, Poornima; Mishra, Hirdyesh; Unnikrishnan, V. K.; Singh, Bachcha; Singh, Ranjan K.

    2016-02-01

    Study of copper complex of creatinine and urea is very important in life science and medicine. In this paper, spectroscopic and structural study of a newly synthesized heteroligand complex of copper with creatinine and urea has been discussed. Structural studies have been carried out using DFT calculations and spectroscopic analyses were carried out by FT-IR, Raman, UV-vis absorption and fluorescence techniques. The copper complex of creatinine and the heteroligand complex were found to have much increased water solubility as compared to pure creatinine. The analysis of FT-IR and Raman spectra helps to understand the coordination properties of the two ligands and to determine the probable structure of the heteroligand complex. The LIBS spectra of the heteroligand complex reveal that the complex is free from other metal impurities. UV-visible absorption spectra and the fluorescence emission spectra of the aqueous solution of Cu-Crn-urea heteroligand complex at different solute concentrations have been analyzed and the complex is found to be rigid and stable in its monomeric form at very low concentrations.

  19. Spectroscopic studies of drugs used in the treatment of malignant tumors in ophthalmology

    NASA Astrophysics Data System (ADS)

    Pascu, Mihail-Lucian; Carstocea, Benone D.; Staicu, Angela; Ionita, Marcel A.; Truica, Sorina; Pascu, Ruxandra

    2001-10-01

    Two classes of substances which may be used in the treatment of malignant tumors in ophthalmology are studied from the point of view of their spectroscopic properties: synthetic porphyrines such as TNP, TPP, TSPP and Zn-TSPP and cytostatics such as 5-fluorouracil. The absorption, excitation and fluorescence spectra of the porphyrins are measured in water and DMSO solutions to allow their efficient use in photodynamic therapy studies at irradiation with UV-laser light. A spectroscopic study of 5-fluorouracyl, a cytostatic drug used in the treatment of ophthalmologic tumors is reported. Absorption, fluorescence excitation/emission spectra were measured for solutions of 5-fluorouracyl at 5 X 10-5 M concentration. The effects of UV-VIS irradiation of on the 5-fluorouracyl solutions were investigated. The irradiation was performed with a classical Xe lamp having a power density of 11 mW/cm2, at time intervals between 15 min and 60 min. While the absorption is not affected by light irradiation, the fluorescence of the solutions is increasing with the irradiation duration.

  20. IR and UV spectroscopic studies at low temperature: C2N2

    NASA Astrophysics Data System (ADS)

    Benilan, Y.; Arzoumanian, E.; Es-Sebbar, Et.; Ferradaz, T.; Fray, N.; Jolly, A.; Gazeau, M.-C.; Schwell, M.

    2008-09-01

    Titan's atmosphere is mainly made of nitrogen and methane and is furthermore very rich in organic molecules. Hydrocarbons are formed by the photodissociation of CH4 and nitriles are created by dissociation of N2 followed by reactions with hydrocarbons. In order to understand the physicochemical mechanisms responsible for the evolution of Titan's atmosphere, photochemical models are built. The latter needs constraints for the determination of vertical profiles of organic compounds, from the higher thermosphere down to the lower stratosphere. They also need wavelength dependant photodissociation rates as input parameters. Vertical profiles can be retrieved from Cassini observations along the entire atmosphere, in particular by limb sounding using Cassini's UVIS and CIRS spectrometers. However, in order to interpret data obtained by these instruments, precise spectroscopic parameters and their dependence on temperature are needed. We will review the current knowledge in this field of planetary spectroscopy and point out the lack of spectroscopic parameters of already detected species. These parameters are especially needed for radiative transfer calculations at low temperatures. We will focus our talk on the Cyanogen molecule (C2N2) which has been observed in Titan's atmosphere in the FIR domain, around 230 cm-1. We will present the latest spectroscopic studies we have performed on this molecule which cover the entire spectrum from the mid- infrared to the vacuum ultraviolet spectral region. Integrated band intensities have been determined for all bands in the infrared. In the ultraviolet domain, we have determined absolute cross sections from 350 down to 80 nm covering six orders of magnitude for the absorption coefficient. We will also show how temperature can influence VUV absorption coefficients. The corresponding implications of temperature dependant absorption data on the interpretation of UVIS observations will be discussed.

  1. Theoretical DFT study on spectroscopic signature and molecular dynamics of neurotransmitter and effect of hydrogen removal

    NASA Astrophysics Data System (ADS)

    Mukherjee, V.; Singh, N. P.; Yadav, R. A.

    2013-04-01

    Vibrational spectroscopic study has been made for the serotonin molecule and its deprotonated form. The Infrared and Raman spectra in optimum geometry of these two molecules are calculated using density functional theorem and the normal modes are assigned using potential energy distributions (PEDs) which are calculated using normal coordinate analysis method. The vibrational frequencies of these two molecules are reported and a comparison has been made. The effect of removal of the hydrogen atom from the serotonin molecule upon its geometry and vibrational frequencies are studied. Electronic structures of these two molecules are also studied using natural bond orbital (NBO) analysis. Theoretical Raman spectrum of serotonin at different exciting laser frequencies and at different temperatures are obtained and the results are discussed. Present study reveals that some wrong assignments had been made for serotonin molecule in earlier study.

  2. Laser Spectroscopic and Theoretical Studies of the Structures and Encapsulation Motifs of Functional Molecules

    SciTech Connect

    Ebata, Takayuki; Kusaka, Ryoji; Xantheas, Sotiris S.

    2015-02-01

    Extensive laser spectroscopic and theoretical studies have been recently carried out with the aim to reveal the structure and dynamics of encapsulation complexes in the gas phase. The characteristics of the encapsulation complexes are governed by the fact that (i) most of the host molecules are flexible and (ii) the complexes form high dimensional structures by using weak non-covalent interactions. These characteristics result in the possibility of the coexistence of many conformers in close energetic proximity. The combination of supersonic jet/laser spectroscopy and high level quantum chemical calculations is essential in tackling these challenging problems. In this report we describe our recent studies on the structures and dynamics of the encapsulation complexes formed by calix[4]arene (C4A), dibenzo-18-crown-6-ether (DB18C6), and benzo-18-crown-6-ether (B18C6) "hosts" interacting with N2, acetylene, water, and ammonia "guest" molecules. The gaseous host-guest complexes are generated under jet-cooled conditions. We apply various laser spectroscopic methods to obtain the conformer- and isomer-specified electronic and IR spectra. The experimental results are complemented with quantum chemical calculations ranging from density functional theory to high level first principles calculations at the MP2 and CCSD(T) levels of theory. We discuss the possible conformations of the bare host molecules, the structural changes they undergo upon complexation, and the key interactions that are responsible in stabilizing the specific complexes

  3. Laser spectroscopic and theoretical studies of the structures and encapsulation motifs of functional molecules

    SciTech Connect

    Ebata, Takayuki; Kusaka, Ryoji; Xantheas, Sotiris S.

    2015-01-22

    Extensive laser spectroscopic and theoretical studies have been recently carried out with the aim to reveal the structure and dynamics of encapsulation complexes in the gas phase. The characteristics of the encapsulation complexes are governed by the fact that (i) most of the host molecules are flexible and (ii) the complexes form high dimensional structures by using weak non-covalent interactions. These characteristics result in the possibility of the coexistence of many conformers in close energetic proximity. The combination of supersonic jet/laser spectroscopy and high level quantum chemical calculations is essential in tackling these challenging problems. In this report we describe our recent studies on the structures and dynamics of the encapsulation complexes formed by calix[4]arene (C4A), dibenzo-18-crown-6-ether (DB18C6), and benzo-18-crown-6-ether (B18C6) 'hosts' interacting with N{sub 2}, acetylene, water, and ammonia 'guest' molecules. The gaseous host-guest complexes are generated under jet-cooled conditions. We apply various laser spectroscopic methods to obtain the conformer- and isomer-specified electronic and IR spectra. The experimental results are complemented with quantum chemical calculations ranging from density functional theory to high level first principles calculations at the MP2 and CCSD(T) levels of theory. We discuss the possible conformations of the bare host molecules, the structural changes they undergo upon complexation, and the key interactions that are responsible in stabilizing the specific complexes.

  4. Corrosion Behavior of Surface-Treated Implant Ti-6Al-4V by Electrochemical Polarization and Impedance Studies

    NASA Astrophysics Data System (ADS)

    Paul, Subir; Yadav, Kasturi

    2011-04-01

    Implant materials for orthopedic and heart surgical services demand a better corrosion resistance material than the presently used titanium alloys, where protective oxide layer breaks down on a prolonged stay in aqueous physiological human body, giving rise to localized corrosion of pitting, crevice, and fretting corrosion. A few surface treatments on Ti alloy, in the form of anodization, passivation, and thermal oxidation, followed by soaking in Hank solution have been found to be very effective in bringing down the corrosion rate as well as producing high corrosion resistance surface film as reflected from electrochemical polarization, cyclic polarization, and Electrochemical Impedance Spectroscopy (EIS) studies. The XRD study revealed the presence of various types of oxides along with anatase and rutile on the surface, giving rise to high corrosion resistance film. While surface treatment of passivation and thermal oxidation could reduce the corrosion rate by 1/5th, anodization in 0.3 M phosphoric acid at 16 V versus stainless steel cathode drastically brought down the corrosion rate by less than ten times. The mechanism of corrosion behavior and formation of different surface films is better understood from the determination of EIS parameters derived from the best-fit equivalent circuit.

  5. Impedance and structural studies on plasticized PCL-LiSO3CF3-SiO2 polymer electrolytes.

    PubMed

    Ng, B C; Wong, H Y; You, A H

    2014-07-01

    Plasticized polymer electrolytes in this study are consist of biodegradable polycaprolactone (PCL) as a host, ethylene carbonate (EC) as a plasticizer, lithium triflate (LiSO3CF3) as salt and nanocomposite silicon dioxide (SiO2) as filler. Solution cast technique is used in the preparation of the plasticized polymer electrolytes. The electrical properties of the plasticized polymer electrolytes with different composition of lithium salt, plasticizer and nano-sized filler are reported in this paper. Conductivity as high as 4.30 x 10(-3) S cm(-1) is obtained in ambient temperature. Ionic conductivity of the plasticized polymer electrolytes are measured using electrochemistry impedance spectroscopy (EIS). The structural and complex formations are studied by X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy. The ionic conductivity result can be further verified and supported by XRD and FTIR reading in which the ionic conductivity is directly proportional to the amorphous phase behaviour of the sample. PMID:24758066

  6. Study of benzotriazole as corrosion inhibitors of carbon steel in chloride solution containing hydrogen sulfide using electrochemical impedance spectroscopy (EIS)

    SciTech Connect

    Solehudin, Agus; Nurdin, Isdiriayani

    2014-03-24

    Corrosion and inhibition studies on API 5LX65 carbon steel in chloride solution containing various concentrations of benzotriazole has been conducted at temperature of 70°C using Electrochemical Impedance Spectroscopy (EIS). Corroded carbon steel surface with and without inhibitor have been observed using X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Energy Dispersive Spectroscopy (EDS). The objectives of this research are to study the performance of benzotriazole as corrosion inhibitors. The experimental results of carbon steel corrosion in 3.5% NaCl solution containing 500 mg/l H{sub 2}S at different BTAH concentrations showed that corrosion rate of carbon steel decreases with increasing of BTAH concentrations from 0 to 10 mmol/l. The inhibition efficiency of BTAH was found to be affected by its concentration. The optimum efficiency obtained of BTAH is 93% at concentration of 5 mmol/l. The result of XRD and EDS analysis reveal the iron sulfide (FeS) formation on corroded carbon steel surface without inhibitor. The EDS spectrum show the Nitrogen (N) bond on carbon steel surface inhibited by BTAH.

  7. A theoretical study of the acoustic impedance of orifices in the presence of a steady grazing flow

    NASA Technical Reports Server (NTRS)

    Rice, E. J.

    1976-01-01

    An analysis of the oscillatory fluid flow in the vicinity of a circular orifice with a steady grazing flow is presented. The study is similar to that of Hersh and Rogers but with the addition of the grazing flow. Starting from the momentum and continuity equations, a considerably simplified system of partial differential equations is developed with the assumption that the flow can be described by an oscillatory motion superimposed upon the known steady flow. The equations are seen to be linear in the region where the grazing flow effects are dominant, and a solution and the resulting orifice impedance are presented for this region. The nonlinearity appears to be unimportant for the usual conditions found in aircraft noise suppressors. Some preliminary conclusions of the study are that orifice resistance is directly proportional to grazing flow velocity (known previously from experimental data) and that the orifice inductive (mass reactance) end correction is not a function of grazing flow. This latter conclusion is contrary to the widely held notion that grazing flow removes the effect of the orifice inductive end correction. This conclusion also implies that the experimentally observed total inductance reduction with grazing flow might be in the flow within the orifice rather than in the end correction.

  8. Study of benzotriazole as corrosion inhibitors of carbon steel in chloride solution containing hydrogen sulfide using electrochemical impedance spectroscopy (EIS)

    NASA Astrophysics Data System (ADS)

    Solehudin, Agus; Nurdin, Isdiriayani

    2014-03-01

    Corrosion and inhibition studies on API 5LX65 carbon steel in chloride solution containing various concentrations of benzotriazole has been conducted at temperature of 70°C using Electrochemical Impedance Spectroscopy (EIS). Corroded carbon steel surface with and without inhibitor have been observed using X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Energy Dispersive Spectroscopy (EDS). The objectives of this research are to study the performance of benzotriazole as corrosion inhibitors. The experimental results of carbon steel corrosion in 3.5% NaCl solution containing 500 mg/l H2S at different BTAH concentrations showed that corrosion rate of carbon steel decreases with increasing of BTAH concentrations from 0 to 10 mmol/l. The inhibition efficiency of BTAH was found to be affected by its concentration. The optimum efficiency obtained of BTAH is 93% at concentration of 5 mmol/l. The result of XRD and EDS analysis reveal the iron sulfide (FeS) formation on corroded carbon steel surface without inhibitor. The EDS spectrum show the Nitrogen (N) bond on carbon steel surface inhibited by BTAH.

  9. Low temperature FTIR, Raman, NMR spectroscopic and theoretical study of hydroxyethylammonium picrate

    NASA Astrophysics Data System (ADS)

    Sudharsana, N.; Sharma, A.; Kuş, N.; Fausto, R.; Luísa Ramos, M.; Krishnakumar, V.; Pal, R.; Guru Row, T. N.; Nagalakshmi, R.

    2016-01-01

    A combined experimental (infrared, Raman and NMR) and theoretical quantum chemical study is performed on the charge-transfer complex hydroxyethylammonium picrate (HEAP). The infrared (IR) spectra for HEAP were recorded at various temperatures, ranging from 16 K to 299 K, and the Raman spectrum was recorded at room temperature. A comparison of the experimental IR and Raman spectra with the corresponding calculated spectra was done, in order to facilitate interpretation of the experimental data. Formation of the HEAP complex is evidenced by the presence of the most prominent characteristic bands of the constituting groups of the charge-transfer complex [e.g., NH3+, CO- and NO2]. Vibrational spectroscopic analysis, together with natural bond orbital (NBO) and theoretical charge density analysis in the crystalline phase, was used to shed light on relevant structural details of HEAP resulting from deprotonation of picric acid followed by formation of a hydrogen bond of the N-H⋯OC type between the hydroxyethylammonium cation and the picrate. 13C and 1H NMR spectroscopic analysis are also presented for the DMSO-d6 solution of the compound revealing that in that medium the HEAP crystal dissolves forming the free picrate and hydroxyethylammonium ions. Finally, the electron excitation analysis of HEAP was performed in an attempt to determine the nature of the most important excited states responsible for the NLO properties exhibited by the compound.

  10. A NEAR-INFRARED SPECTROSCOPIC STUDY OF YOUNG FIELD ULTRACOOL DWARFS

    SciTech Connect

    Allers, K. N.; Liu, Michael C.

    2013-08-01

    We present a near-infrared (0.9-2.4 {mu}m) spectroscopic study of 73 field ultracool dwarfs having spectroscopic and/or kinematic evidence of youth ( Almost-Equal-To 10-300 Myr). Our sample is composed of 48 low-resolution (R Almost-Equal-To 100) spectra and 41 moderate-resolution spectra (R {approx}> 750-2000). First, we establish a method for spectral typing M5-L7 dwarfs at near-IR wavelengths that is independent of gravity. We find that both visual and index-based classification in the near-IR provides consistent spectral types with optical spectral types, though with a small systematic offset in the case of visual classification at J and K band. Second, we examine features in the spectra of {approx}10 Myr ultracool dwarfs to define a set of gravity-sensitive indices based on FeH, VO, K I, Na I, and H-band continuum shape. We then create an index-based method for classifying the gravities of M6-L5 dwarfs that provides consistent results with gravity classifications from optical spectroscopy. Our index-based classification can distinguish between young and dusty objects. Guided by the resulting classifications, we propose a set of low-gravity spectral standards for the near-IR. Finally, we estimate the ages corresponding to our gravity classifications.

  11. Studies on Nephrite and Jadeite Jades by Fourier Transform Infrared (ftir) and Raman Spectroscopic Techniques

    NASA Astrophysics Data System (ADS)

    Tan, T. L.; Ng, L. L.; Lim, L. C.

    2013-10-01

    The mineralogical properties of black nephrite jade from Western Australia are studied by Fourier transform infrared (FTIR) spectroscopy using both transmission and specular reflectance techniques in the 4000-400 cm-1 wavenumber region. The infrared absorption peaks in the 3700-3600 cm-1 region which are due to the O-H stretching mode provides a quantitative analysis of the Fe/(Fe+Mg) ratio in the mineral composition of jade samples. The Fe/(Fe+Mg) percentage in black nephrite is found to be higher than that in green nephrite, but comparable to that of actinolite (iron-rich nephrite). This implies that the mineralogy of black nephrite is closer to actinolite than tremolite. The jade is also characterized using Raman spectroscopy in the 1200-200 cm-1 region. Results from FTIR and Raman spectroscopic data of black nephrite jade are compared with those of green nephrite jade from New Zealand and jadeite jade from Myanmar. Black nephrite appears to have a slightly different chemical composition from green nephrite. Spectra from FTIR and Raman spectroscopic techniques were found to be useful in differentiating black nephrite, green nephrite, and green jadeite jades. Furthermore, data on refractive index, specific gravity, and hardness of black nephrite jade are measured and compared with those of green nephrite and of jadeite jade.

  12. Near-Infrared Spectroscopic Study of AA Tau: Water and OH Observations

    NASA Astrophysics Data System (ADS)

    Brown, Logan Ryan; Gibb, Erika

    2014-06-01

    To understand our own solar origins, we must investigate the composition of the protoplanetary disk from which the solar system formed. To infer this, we study analogs to the early solar system called T Tauri stars. These objects are low-mass, pre-main sequence stars surrounded by circumstellar disks of material from which planets are believed to form. We present high-resolution (λ/Δλ˜25,000), near-infrared spectroscopic data from the T Tauri star AA Tau using NIRSPEC at the Keck II telescope, located on Mauna Kea, HI, taken in 2009 and 2010. AA Tau has a close to edge-on geometry, with an inclination of 70° ± 10° (Donati et al. 2010). Objects must have a nearly edge-on inclination for the disk to be sampled via absorption line spectroscopy. We observed strong absorption lines of both water and OH to which a spectroscopic model was fit in order for us to determine column density and rotational temperature. These near-infrared observations complement the work being done with ALMA, allowing us to probe the inner most disk regions and the chemistry contained within while ALMA primarily samples and is most sensitive to the outer disk.

  13. Ab initio study of the O4H(+) novel species: spectroscopic fingerprints to aid its observation.

    PubMed

    Xavier, F George D; Hernández-Lamoneda, Rámon

    2015-06-28

    A detailed ab initio characterization of the structural, energetic and spectroscopic properties of the novel O4H(+) species is presented. The equilibrium structures and relative energies of all multiplet states have been determined systematically by analyzing static and dynamical correlation effects. The two and three body dissociation processes have been studied and indicate the presence of conical intersections in various states including the ground state. Comparison with available thermochemical data is very good, supporting the applied methodology. The reaction, H3(+) + O4→ O4H(+) + H2, was found to be exothermic ΔH = -19.4 kcal mol(-1) and therefore, it is proposed that the product in the singlet state could be formed in the interstellar medium (ISM) via collision processes. To aid in its laboratory or radioastronomy detection in the interstellar medium we determined spectroscopic fingerprints. It is estimated for the most stable geometry of O4H(+) dipole allowed electronic transitions in the visible region at 429 nm and 666 nm, an intense band at 1745 cm(-1) in the infrared and signals at 40.6, 81.2 and 139.2 GHz in the microwave region at 10, 50 and 150 K respectively, relevant for detection in the ISM. PMID:26028209

  14. Two-dimensional infrared study of 3-azidopyridine as a potential spectroscopic reporter of protonation state

    SciTech Connect

    Nydegger, Michael W.; Dutta, Samrat; Cheatum, Christopher M.

    2010-10-07

    The lack of general spectroscopic probes that can be used in a range of systems to probe kinetics and dynamics is a major obstacle to the widespread application of two-dimensional infrared (2D IR) spectroscopy. We have studied 3-azidopyridine to characterize its potential as a probe of the protonation state of the pyridine ring. We find that the azido-stretching vibration is split by accidental Fermi resonance interactions with one or more overtones and combination states. Using 2D IR spectroscopy, we determine the state structure of the resulting eigenstates for complexes of 3-azidopyridine with formic acid and trifluoroacetic acid in which the pyridine ring is unprotonated and protonated, respectively. Based on the measurements, we develop a two-oscillator depurturbation model to determine the energies and couplings of the zeroth-order azido-stretching state and the perturbing dark state that couples to it. Based on these results, we conclude that the azido-stretching vibration is, in fact, sensitive to the protonation state of the pyridine shifting up in frequency by 8 cm{sup -1} in the complex with trifluoroacetic acid relative to the formic acid complex. These results suggest that, although 3-azidopyridine is not suitable as a spectroscopic probe, the approach of employing an organic azide as a remote probe of protonation state holds significant promise.

  15. A single-photon fluorescence and multi-photon spectroscopic study of atherosclerotic lesions

    NASA Astrophysics Data System (ADS)

    Smith, Michael S. D.; Ko, Alex C. T.; Ridsdale, Andrew; Schattka, Bernie; Pegoraro, Adrian; Hewko, Mark D.; Shiomi, Masashi; Stolow, Albert; Sowa, Michael G.

    2009-06-01

    In this study we compare the single-photon autofluorescence and multi-photon emission spectra obtained from the luminal surface of healthy segments of artery with segments where there are early atherosclerotic lesions. Arterial tissue was harvested from atherosclerosis-prone WHHL-MI rabbits (Watanabe heritable hyperlipidemic rabbit-myocardial infarction), an animal model which mimics spontaneous myocardial infarction in humans. Single photon fluorescence emission spectra of samples were acquired using a simple spectrofluorometer set-up with 400 nm excitation. Samples were also investigated using a home built multi-photon microscope based on a Ti:sapphire femto-second oscillator. The excitation wavelength was set at 800 nm with a ~100 femto-second pulse width. Epi-multi-photon spectroscopic signals were collected through a fibre-optics coupled spectrometer. While the single-photon fluorescence spectra of atherosclerotic lesions show minimal spectroscopic difference from those of healthy arterial tissue, the multi-photon spectra collected from atherosclerotic lesions show marked changes in the relative intensity of two-photon excited fluorescence (TPEF) and second-harmonic generation (SHG) signals when compared with those from healthy arterial tissue. The observed sharp increase of the relative SHG signal intensity in a plaque is in agreement with the known pathology of early lesions which have increased collagen content.

  16. Lanthanide and transition metal complexes of bioactive coumarins: molecular modeling and spectroscopic studies.

    PubMed

    Georgieva, I; Mihaylov, Tz; Trendafilova, N

    2014-06-01

    The present paper summarizes theoretical and spectroscopic investigations on a series of active coumarins and their lanthanide and transition metal complexes with application in medicine and pharmacy. Molecular modeling as well as IR, Raman, NMR and electronic spectral simulations at different levels of theory were performed to obtain important molecular descriptors: total energy, formation energy, binding energy, stability, conformations, structural parameters, electron density distribution, molecular electrostatic potential, Fukui functions, atomic charges, and reactive indexes. The computations are performed both in gas phase and in solution with consideration of the solvent effect on the molecular structural and energetic parameters. The investigations have shown that the advanced computational methods are reliable for prediction of the metal-coumarin binding mode, electron density distribution, thermodynamic properties as well as the strength and nature of the metal-coumarin interaction (not experimentally accessible) and correctly interpret the experimental spectroscopic data. Known results from biological tests for cytotoxic, antimicrobial, anti-fungal, spasmolytic and anti-HIV activities on the studied metal complexes are reported and discussed. PMID:24680836

  17. Spectroscopic, crystallographic and theoretical studies of lasalocid complex with ammonia and benzylamine

    NASA Astrophysics Data System (ADS)

    Huczyński, Adam; Janczak, Jan; Rutkowski, Jacek; Brzezinski, Bogumil

    A natural antibiotic - Lasalocid is able to form stable complexes with ammonia and organic amines. New complexes of lasalocid with benzylamine and ammonia were obtained in the crystal forms and studied using X-ray, FT-IR, 1H NMR, 13C NMR and DFT methods. These studies have shown that in both complexes the proton is transferred from the carboxylic group to the amine group with the formation of a pseudo-cyclic structure of lasalocid anion complexing the protonated amine or NH4+ cation. The spectroscopic and DFT studies demonstrated that the structure of the complex formed between Lasalocid and benzylamine in the solid is also conserved in the solution and gas phase. In contrast, the structure of the complex formed between lasalocid and ammonium cation found in the solid state undergoes dissociation in chloroform solution accompanied with a change in the coordination form of the NH4+ cation.

  18. Synthesis, spectroscopic characterization, DNA interaction and antibacterial study of metal complexes of tetraazamacrocyclic Schiff base

    NASA Astrophysics Data System (ADS)

    Shakir, Mohammad; Khanam, Sadiqa; Firdaus, Farha; Latif, Abdul; Aatif, Mohammad; Al-Resayes, Saud I.

    The template condensation reaction between benzil and 3,4-diaminotoulene resulted mononuclear 12-membered tetraimine macrocyclic complexes of the type, [MLCl2] [M = Co(II), Ni(II), Cu(II) and Zn(II)]. The synthesized complexes have been characterized on the basis of the results of elemental analysis, molar conductance, magnetic susceptibility measurements and spectroscopic studies viz. FT-IR, 1H and 13C NMR, FAB mass, UV-vis and EPR. An octahedral geometry has been envisaged for all these complexes, while a distorted octahedral geometry has been noticed for Cu(II) complex. Low conductivity data of all these complexes suggest their non-ionic nature. The interactive studies of these complexes with calf thymus DNA showed that the complexes are avid binders of calf thymus DNA. The in vitro antibacterial studies of these complexes screened against pathogenic bacteria proved them as growth inhibiting agents.

  19. Spectroscopic study of N-acetylcysteine and N-acetylcystine/hydrogen peroxide complexation

    NASA Astrophysics Data System (ADS)

    Picquart, Michel; Abedinzadeh, Zohreh; Grajcar, Lydie; Baron, Marie Héléne

    1998-03-01

    A spectroscopic study of N-acetylcysteine (RSH) and N-acetylcystine (RSSR) has been performed using infrared absorption and Raman scattering in order to pinpoint the sites of complexation of these two species with H 2O 2. Molecules of RSH and RSSR were studied in KBr pellets, and in aqueous solutions of H 2O, D 2O and H 2O with H 2O 2 (1 mol l -1) to characterize the specific influence of the solvent molecules. A time-resolved Raman study was performed for RSH-H 2O 2 in aqueous solution at 1:1 molar ratio in order to observe the formation of RSSR and to discuss the mechanism of this redox reaction.

  20. Detection of Non-Cavitated Occlusal Caries with Impedance Spectroscopy and Laser Fluorescence: an In Vitro Study

    PubMed Central

    Mortensen, Diana; Dannemand, Katrine; Twetman, Svante; Keller, Mette Kirstine

    2014-01-01

    Objective: To evaluate the performance of an impedance spectroscopy technology for detecting non-cavitated occlusal caries lesions in permanent teeth in vitro. The method was compared with a commonly used laser fluorescence device and validated against histology. Material and Methodology: A non-cavitated sample of 100 extracted posterior teeth was randomly selected and assessed for caries on enamel and dentin level with aid of CarioScan PRO (ACIS) and DIAGNOdent pen (LF pen) by three examiners. After the measurements, the extension of the lesion was histologically determined as gold standard. Sensitivity, specificity, accuracy and receiver-operating curves were calculated. Intra- and inter-examiner reproducibility was expressed by intra class correlation coefficients. Results: The histological caries prevalence was 99% and 41% exhibited dentin caries. The ACIS technique displayed high specificities but almost negligible sensitivities at readings >50. A similar pattern was noted for the LF pen at readings >30. The intra- and inter-examiner reproducibility varied between 0.47 and 0.98 and the values were generally lower for the ACIS technique than for the LF pen. The inter-examiner agreement reached excellent levels with both methods. Conclusions: In vitro,the ACIS technique showed a low ability to disclose occlusal caries lesions in the enamel and/or dentin of non-cavitated permanent molars. However, further in vivo studies of permanent occlusal surfaces are needed to mirror the clinical situation. PMID:24799965

  1. Use of 3-D magnetic resonance electrical impedance tomography in detecting human cerebral stroke: a simulation study*

    PubMed Central

    Gao, Nuo; Zhu, Shan-an; He, Bin

    2005-01-01

    We have developed a new three dimensional (3-D) conductivity imaging approach and have used it to detect human brain conductivity changes corresponding to acute cerebral stroke. The proposed Magnetic Resonance Electrical Impedance Tomography (MREIT) approach is based on the J-Substitution algorithm and is expanded to imaging 3-D subject conductivity distribution changes. Computer simulation studies have been conducted to evaluate the present MREIT imaging approach. Simulations of both types of cerebral stroke, hemorrhagic stroke and ischemic stroke, were performed on a four-sphere head model. Simulation results showed that the correlation coefficient (CC) and relative error (RE) between target and estimated conductivity distributions were 0.9245±0.0068 and 8.9997%±0.0084%, for hemorrhagic stroke, and 0.6748±0.0197 and 8.8986%±0.0089%, for ischemic stroke, when the SNR (signal-to-noise radio) of added GWN (Gaussian White Noise) was 40. The convergence characteristic was also evaluated according to the changes of CC and RE with different iteration numbers. The CC increases and RE decreases monotonously with the increasing number of iterations. The present simulation results show the feasibility of the proposed 3-D MREIT approach in hemorrhagic and ischemic stroke detection and suggest that the method may become a useful alternative in clinical diagnosis of acute cerebral stroke in humans. PMID:15822161

  2. Low temperature dielectric and impedance studies on magnetoelectric Pb(Fe0.5Nb0.5)O3 ceramic

    NASA Astrophysics Data System (ADS)

    Matteppanavar, Shidaling; Shivaraja, I.; Rayaprol, Sudhindra; Angadi, Basavaraj

    2016-05-01

    The structural, microstructural, low temperature dielectric and impedance properties of Pb(Fe0.5Nb0.5)O3 (PFN) ceramic prepared by single step solid-state reaction method have been investigated. Processing parameters such as calcination, sintering temperature and sintering durations were optimized to get better dielectric properties. It was found that the above ceramics sintered at 1050 °C for 4 hr exhibited single phase, maximum density and uniform microstructure. X-ray diffraction (XRD) and neutron diffraction (ND) reveals that the system exhibit single phase without any kind of secondary phases at room temperature (RT) with monoclinic crystal structure (Cm). Surface morphology of the compounds was studied by Scanning electron microscope (SEM). Impedance spectroscopy is used to study the electrical behaviour of PFN in the frequency range from 100Hz to 1MHz and in the temperature range from 120 to 293 K. The frequency-dependent electrical data are analyzed by impedance formalisms. The complex impedance shows the relaxation (conduction) mechanism in the sample.

  3. Electrochemical impedance spectroscopy investigations of a microelectrode behavior in a thin-layer cell: Experimental and theoretical studies.

    PubMed

    Gabrielli, C; Keddam, M; Portail, N; Rousseau, P; Takenouti, H; Vivier, V

    2006-10-19

    Electrochemical impedance spectroscopy experiments were performed on a microdisk electrode in a thin-layer cell using a scanning electrochemical microscope for controlling the cell geometry. Experimental data showed that when the thin-layer thickness diminished, an additional low-frequency response appeared. It was ascribed to the radial diffusion of the electroactive species and was strongly dependent on the thin-layer dimensions (both thickness and diameter). Moreover, the numerical simulation of the impedance diagrams by finite element method calculations confirmed this behavior. An equivalent circuit based on a Randles-type circuit was proposed. Thus, the diffusion was described by introducing two electrical elements: one for the spherical diffusion and the other for the radial contribution. A nonlinear Simplex algorithm was used, and this circuit was shown to fit the impedance diagrams with a good accuracy. PMID:17034233

  4. Swiss bare mice: a suitable model for transcutaneous in vivo Raman spectroscopic studies of breast cancer.

    PubMed

    Bhattacharjee, T; Kumar, Piyush; Maru, G; Ingle, A; Krishna, C Murali

    2014-01-01

    Breast cancer is the most common cancer affecting females worldwide. As early detection results in better prognosis, screening tools for breast cancer are being explored. Raman spectroscopy, a rapid, objective, and noninvasive tool, has shown promising results in the diagnosis of several cancers including breast cancer. For development as a screening tool, a study of spectral signatures associated with breast cancer progression is imperative. However, such studies are not possible in human subjects. Hence, there is a need for a suitable animal model, which is conducive to transcutaneous in vivo Raman spectroscopic measurements of breast with minimal interference from skin and hair and has contribution from functional mammary epithelium of breast. In this study, rodent models like C57, Swiss albino, Swiss bare, agouti mice, and Sprague-Dawley rats were evaluated. Among these models, transcutaneous breast spectra of hairless Swiss bare mice have the best signal-to-noise ratio and were closest to reported ex vivo as well as intraoperative in vivo human breast spectra. Principal component-linear discriminant analysis of several anatomical sites confirms minimal skin interference and suggests contribution from functional mammary epithelium of breast. Moreover, transcutaneous spectra from normal breast and breast tumors of Swiss bare mice could be classified with 99% efficiency, which is better than the previous reports. Thus, Swiss bare mice model may be better suited for transcutaneous in vivo Raman spectroscopic studies of breast physiology and pathology, especially breast cancer. Prospectively, in addition to cancer progression, breast-to-bone metastasis can also be studied, since these anatomical sites can be uniquely classified. PMID:23708992

  5. Infrared Spectroscopic Studies with the Stratospheric Observatory for Infrared Astronomy (sofia)

    NASA Astrophysics Data System (ADS)

    Gehrz, R. D.; Becklin, E. E.

    2011-06-01

    The joint U.S. and German Stratospheric Observatory for Infrared Astronomy (SOFIA) will be a premier facility for studying the physics and chemistry of the interstellar medium and the stellar evolution process for many decades. SOFIA's first-generation instrument complement includes broadband imagers, moderate resolution spectrographs capable of resolving broad features due to dust and large molecules, and high resolution spectrometers suitable for kinematic studies of molecular and atomic gas lines at km/s resolution. SOFIA spectroscopic science applications will be discussed, with special emphasis on investigations related to infrared spectroscopy of astrophysical gas, grains, and ices. First light images and early science results related to these topics will be presented.

  6. Spectroscopic study of light scattering in linear alkylbenzene for liquid scintillator neutrino detectors

    NASA Astrophysics Data System (ADS)

    Zhou, Xiang; Liu, Qian; Han, Junbo; Zhang, Zhenyu; Zhang, Xuan; Ding, Yayun; Zheng, Yangheng; Zhou, Li; Cao, Jun; Wang, Yifang

    2015-11-01

    We have set up a light scattering spectrometer to study the depolarization of light scattering in linear alkylbenzene. The scattering spectra show that the depolarized part of light scattering is due to Rayleigh scattering. The additional depolarized Rayleigh scattering can make the effective transparency of linear alkylbenzene much better than expected. Therefore, sufficient scintillation photons can transmit through large liquid scintillator detector, such as that of the JUNO experiment. Our study is crucial to achieving an unprecedented energy resolution of 3 %/√{E{(MeV)}} required for the JUNO experiment to determine the neutrino mass hierarchy. The spectroscopic method can also be used to examine the depolarization of other organic solvents used in neutrino experiments.

  7. Electronic properties of diphenyl-s-tetrazine and some related oligomers. An spectroscopic and theoretical study

    NASA Astrophysics Data System (ADS)

    Moral, Mónica; García, Gregorio; Peñas, Antonio; Garzón, Andrés; Granadino-Roldán, José M.; Melguizo, Manuel; Fernández-Gómez, Manuel

    2012-10-01

    This work presents a theoretical and spectroscopic study on the electronic and structural properties of the diphenyl-s-tetrazine molecule (Ph2Tz) and some oligomeric derivatives. Ph2Tz was synthesized through a variation of Pinner-type reaction which uses N-acetylcysteine as catalyst. Insight into the structure and electronic properties of the title compound was obtained through IR, Raman, UV-Vis spectra in different solvents, and theoretical calculations. Theoretical studies have been extended to different n-mers derivatives up to an ideal molecular wire through the oligomeric approximation, predicting this way electronic properties such as LUMO energy levels, electron affinity and reorganization energy in order to assess their possible applications in molecular electronics.

  8. Spectroscopic study of antileishmanial drug incubated in the promastigotes of Leishmania mexicana

    NASA Astrophysics Data System (ADS)

    Hung, J.; Castillo, J.; Jiménez, G.; Hasegawa, M.; Rodriguez, M.

    2003-11-01

    In this work we present spectroscopic study of Boldine (aporphine alkaloid) that possesses important biological activities, in particular, in interaction with the promastigotes of Leishmania mexicana. The results show the applicability of autofluorescence of this drug to determinate the possible mechanism of its biological action. The blue shift and hyperchromic effect in the emission spectrum of the drug in interaction with the parasite cells indicate an energy transference process between them. The morphological change of cell shape of the promastigotes treated with the drug is observed using confocal microscopy. This morphological cell-shape transformation evidences an important interaction between the drug studied and some protein of the parasite cell. Here we describe for the first time the fluorescence properties of the Boldine in the promastigotes of L. mexicana.

  9. Dielectric studies of boron sub phthalocyanine chloride thin films by admittance spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Kalia, Sameer; Mahajan, Aman; Neerja, Sharma, Anshul Kumar; Kumar, Sanjeev; Bedi, R. K.

    2016-05-01

    The dielectric properties of Boron Sub Phthalocyanine Chloride (Cl-SubPc) thermally deposited on ITO substrate have been studied using admittance spectroscopic techniques. The I-V and capacitance -frequency (C-F) studies at various bias voltages reveal that the mobility of charge carriers decrease with bias voltage, however the conduction phenomenon still remain hopping in nature. From the differential susceptance curve, the contribution of the Schottky barrier contact in the charge carrier concentration was found to be absent. The mobility of charge carriers have been determined using differential susceptance variation and from the phase of admittance curve. The values obtained in two cases have been found to be in agreement with each other.

  10. Robust impedance shaping telemanipulation

    SciTech Connect

    Colgate, J.E.

    1993-08-01

    When a human operator performs a task via a bilateral manipulator, the feel of the task is embodied in the mechanical impedance of the manipulator. Traditionally, a bilateral manipulator is designed for transparency; i.e., so that the impedance reflected through the manipulator closely approximates that of the task. Impedance shaping bilateral control, introduced here, differs in that it treats the bilateral manipulator as a means of constructively altering the impedance of a task. This concept is particularly valuable if the characteristic dimensions (e.g., force, length, time) of the task impedance are very different from those of the human limb. It is shown that a general form of impedance shaping control consists of a conventional power-scaling bilateral controller augmented with a real-time interactive task simulation (i.e., a virtual environment). An approach to impedance shaping based on kinematic similarity between tasks of different scale is introduced and illustrated with an example. It is shown that an important consideration in impedance shaping controller design is robustness; i.e., guaranteeing the stability of the operator/manipulator/task system. A general condition for the robustness of a bilateral manipulator is derived. This condition is based on the structured singular value ({mu}). An example of robust impedance shaping bilateral control is presented and discussed.

  11. Vibrational Spectroscopic Studies on Some Double Alkali Tungstates Belonging to Orthorhombic Class at Room Temperature

    SciTech Connect

    Sharaff, Usha; Bajpai, P. K.; Choudhary, R. N. P.

    2011-11-22

    Room temperature IR and Raman spectra of rubidium lithium tungstate and sodium lithium tungstates belonging to double alkali tungstate family are investigated using group theoretical methods. Observed internal and lattice modes in both systems studied are assigned. Analysis of spectral behavior reveals that the effect of site potential around tungstates ion is weak and the factor group splitting is operative. Differences in the lattice mode mixing and splitting of internal modes is influenced by the statistical ordering between two alkali ions having large and small ionic radii and is explained using size and charge effect observed earlier in scheelite type of structure. Thus, vibrational spectroscopic analysis may be a tool to understand the alkali ion ordering in double alkali systems.

  12. Spectroscopic and theoretical study of the o-vanillin hydrazone of the mycobactericidal drug isoniazid

    NASA Astrophysics Data System (ADS)

    González-Baró, Ana C.; Pis-Diez, Reinaldo; Parajón-Costa, Beatriz S.; Rey, Nicolás A.

    2012-01-01

    A complete and detailed study of the hydrazone obtained from condensation of antituberculous isoniazid (hydrazide of the isonicotinic acid, INH) and o-vanillin (2-hydroxy-3-methoxybenzaldehyde, o-HVa) is performed. It includes structural and spectroscopic analyses, comparing experimental and theoretical results. The compound was obtained as a chloride of the pyridinic salt (INHOVA +Cl -) but it will be referred as INHOVA for the sake of simplicity. The conformational space was searched and optimized geometries were determined both in gas phase and including solvent effects. Vibrational (IR and Raman), electronic and NMR spectra were registered and assigned with the help of computational methods based on the Density Functional Theory. Isoniazid hydrazones are good candidates for therapeutic agents against tuberculosis with conserved efficiency and lower toxicity and resistance than parent INH.

  13. Photoelectron spectroscopic and computational study of (M-CO2)- anions, M = Cu, Ag, Au

    NASA Astrophysics Data System (ADS)

    Zhang, Xinxing; Lim, Eunhak; Kim, Seong K.; Bowen, Kit H.

    2015-11-01

    In a combined photoelectron spectroscopic and computational study of (M-CO2)-, M = Au, Ag, Cu, anionic complexes, we show that (Au-CO2)- forms both the chemisorbed and physisorbed isomers, AuCO 2- and Au-(CO2), respectively; that (Ag-CO2)- forms only the physisorbed isomer, Ag-(CO2); and that (Cu-CO2)- forms only the chemisorbed isomer, CuCO 2- . The two chemisorbed complexes, AuCO 2- and CuCO 2- , are covalently bound, formate-like anions, in which their CO2 moieties are significantly reduced. These two species are examples of electron-induced CO2 activation. The two physisorbed complexes, Au-(CO2) and Ag-(CO2), are electrostatically and thus weakly bound.

  14. Mössbauer spectroscopic studies of Fe-20 wt.% Cr ball milled alloy

    NASA Astrophysics Data System (ADS)

    Pandey, Brajesh; Rao, M. Ananda; Verma, H. C.; Bhargava, S.

    2006-04-01

    Interesting differences were noticed in the alloying process during ball milling of Fe-10 wt.% Cr and Fe-20 wt.% Cr alloys by 57Fe Mössbauer spectroscopic studies. In both cases, there is almost no diffusion of Fe in Cr or vice versa up to 20 h of milling time. As the powders are milled for another 20 h substantive changes occur in the Mössbauer spectra showing atomic level mixing. But the two compositions behave differently with respect to alloying. Fe-20 wt.% Cr sample does not differ much in the hyperfine field distribution as it is milled from 40 to 100 h. On the other hand, the hyperfine field distribution keeps on changing with milling time for Fe-10 wt.% Cr sample even up to 100 h of milling. The average crystallite size is found to be 7.5 nm for Fe-10 wt.% Cr and 6.5 nm in Fe-20 wt.% Cr after milling.

  15. Mössbauer spectroscopic studies of Fe-20 wt.% Cr ball milled alloy

    NASA Astrophysics Data System (ADS)

    Pandey, Brajesh; Ananda Rao, M.; Verma, H. C.; Bhargava, S.

    Interesting differences were noticed in the alloying process during ball milling of Fe-10 wt.% Cr and Fe-20 wt.% Cr alloys by 57Fe Mössbauer spectroscopic studies. In both cases, there is almost no diffusion of Fein Cr or vice versa up to 20 h of milling time. As the powders are milled for another 20 h substantive changes occur in the Mössbauer spectra showing atomic level mixing. But the two. compositions behave differently with respect to alloying. Fe-20 wt.% Cr sample does not differ much in the hyperfine field distribution as it is milled from 40 to 100 h. On the other hand, the hyperfine field distribution keeps on changing with milling time for Fe-10 wt.% Cr sample even up to 100 h of milling. The average crystallite size is found to be 7.5 nm for Fe-10 wt.% Cr and 6.5 nm in Fe-20 wt.% Cr after milling.

  16. Constraining the orbits of small solar system bodies using spectroscopic Doppler shift measurements - a preliminary study

    NASA Astrophysics Data System (ADS)

    Zucker, S.; Tzur, I.

    2015-09-01

    In this short paper we examine whether the measurement of Doppler shifts in the solar light reflected off an asteroid surface may improve the accuracy of the determined orbit. Our results suggest it will be worthwhile to use high-resolution spectrographs, of the exoplanet-hunting type, to measure those Doppler shifts. Spectroscopic Doppler shifts might improve the accuracy of Earth-impact predictions, help to recover ``lost'' near-Earth objects, and may also significantly enhance the knowledge about dynamics of the Kuiper belt. Future high-resolution spectrographs on the VLT and the E-ELT may thus have an important role in studies of Solar-System dynamics and kinematics.

  17. The study of interaction between PFOA/PFOS and uracil by topology quality and spectroscopic analysis

    NASA Astrophysics Data System (ADS)

    Xu, Hui-Ying; Zhu, Jian-Qing; Wang, Wei; Xu, Xiao-Lu; Lu, Yin

    2014-02-01

    It has been established that perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) can be considered as emerging persistent organic pollutants. In recent years, there was increasing distribution of PFOA/PFOS in environmental systems, and accumulation and toxic effects of PFOA/PFOS in human body. In this paper, quantum chemistry methods were employed to study the interaction between perfluorinated organic pollutants and base (uracil). The results showed that there were four stable binding modes between the two perfluorinated compounds with uracil, especially the second mode which caused the most detrimental physiological functional response. NBO analysis showed that reactive hydrogen in the two perfluorinated compounds had the greatest effect on the hydrogen bond. The nature of the hydrogen bond formed between the two perfluorinated compounds and base was investigated using the AIM theory. The changes of spectroscopic properties in complexes were analyzed by IR and NMR spectra.

  18. A dielectric spectroscopic study of the disperse structure of asphaltene solutions at high pressures

    SciTech Connect

    Syunyaev, R.Z.; Sh. Abid, R.

    1994-03-01

    The disperse structure of oil asphaltenes in benzene and toluene solutions at different temperatures and concentrations were studied at pressures up to 1.0 GPa. The polarity of the asphaltene molecules allows the dielectric spectroscopic method to be used. A sharp increase in the relaxation time and the sizes of the asphaltene aggregates, calculated according to the Debye model near the phase transition point, were found in the benzene solution. The pressure value corresponding to crystallization is much higher in the toluene solution, and only the border region can be investigated. An explanation of the pressure dependences of the relaxation times are presented. The activation energies and the coefficients of isothermal compressibility are calculated.

  19. Raman spectroscopic study of “The Malatesta”: A Renaissance painting?

    NASA Astrophysics Data System (ADS)

    Edwards, Howell G. M.; Vandenabeele, Peter; Benoy, Timothy J.

    2015-02-01

    Raman spectroscopic analysis of the pigments on an Italian painting described as a "Full Length Portrait of a Gentleman", known also as the "Malatesta", and attributed to the Renaissance period has established that these are consistent with the historical research provenance undertaken earlier. Evidence is found for the early 19th Century addition of chrome yellow to highlighted yellow ochre areas in comparison with a similar painting executed in 1801 by Sir Thomas Lawrence of John Kemble in the role of Hamlet, Prince of Denmark. The Raman data are novel in that no analytical studies have previously been made on this painting and reinforces the procedure whereby scientific analyses are accompanied by parallel historical research.

  20. Raman spectroscopic study on the excystation process in a single unicellular organism amoeba (Acanthamoeba polyphaga)

    NASA Astrophysics Data System (ADS)

    Lin, Yu-Chung; Perevedentseva, Elena; Cheng, Chia-Liang

    2015-05-01

    An in vivo Raman spectroscopic study of amoeba (Acanthamoeba polyphaga) is presented. The changes of the spectra during the amoeba cyst activation and excystation are analyzed. The spectra show the changes of the relative intensities of bands corresponding to protein, lipid, and carotenoid components during cyst activation. The presence of carotenoids in the amoeba is observed via characteristic Raman bands. These signals in the Raman spectra are intense in cysts but decrease in intensity with cyst activation and exhibit a correlation with the life cycle of amoeba. This work demonstrates the feasibility of using Raman spectroscopy for the detection of single amoeba microorganisms in vivo and for the analysis of the amoeba life activity. The information obtained may have implications for the estimation of epidemiological situations and for the diagnostics and prognosis of the development of amoebic inflammations.

  1. Spectroscopic and nonlinear optical studies of pure and Nd-doped lanthanum strontium borate glasses

    NASA Astrophysics Data System (ADS)

    Harde, G. B.; Muley, G. G.

    2016-05-01

    Borate glasses of the system xNd2O3-(1-x) La2O3-SrCO3-10H3BO3 (with x = 0 and 0.05) were prepared by using a convectional melt quenching technique. The amorphous nature of the quenched glasses has been confirmed by powder X-ray diffraction analysis. In order to study the spectroscopic and nonlinear optical properties of fabricated glasses, ultraviolet-visible transmission spectroscopy and open aperture z-scan measurements have been employed. In Nd doped glasses, the transition 4I9/2 → 4G5/2 + 2G7/2 has found more prominent than the other transitions. Optical band gap energies of glasses have been determined and found less for Nd doped glass.

  2. Spectroscopic-ellipsometric study of native oxide removal by liquid phase HF process

    PubMed Central

    Kurhekar, Anil Sudhakar; Apte, Prakash R

    2014-01-01

    Ex situ spectroscopic ellipsometry (SE) measurements have been employed to investigate the effect of liquid-phase hydrofluoric acid (HF) cleaning on Si<100> surfaces for microelectromechanical systems application. The hydrogen terminated (H-terminated) Si surface was realized as an equivalent dielectric layer, and SE measurements are performed. The SE analyses indicate that after a 20-s 100:5 HF dip with rinse, the Si (100) surface was passivated by the hydrogen termination and remained chemically stable. Roughness of the HF-etched bare Si (100) surface was observed and analyzed by the ex-situ SE. Evidence for desorption of the H-terminated Si surface layer is studied using Fourier transform infrared spectroscopy and ellipsometry, and discussed. This piece of work explains the usage of an ex situ, non-destructive technique capable of showing state of passivation, the H-termination of Si<100> surfaces. PMID:24619506

  3. Spectroscopic studies on the interaction of fluorescein and safranine T in PC liposomes

    NASA Astrophysics Data System (ADS)

    Bozkurt, Ebru; Bayraktutan, Tuğba; Acar, Murat; Toprak, Mahmut

    2013-01-01

    In this study, the fluorescence quenching of fluorescein by safranine T in liposome media had been investigated systematically by fluorescence spectroscopy, UV-vis absorption spectroscopy and fluorescence decay lifetime measurements. The spectroscopic data were analyzed using a Stern-Volmer equation to determine the quenching process. The experimental results showed that the intrinsic fluorescence of fluorescein was strongly quenched by safranine T, and that the quenching mechanism was considered as static quenching by forming a ground-complex. The Stern-Volmer quenching constant Ksv, and the bimolecular quenching constant Kq were estimated. The distances between the donor (fluorescein) and the acceptor (safranine T) were calculated according to the Förster non-radiation energy transfer theory. In addition, the partition coefficient of the safranine T (Kp) in the L-egg lecithin phosphatidylcholine liposomes was also calculated by utilizing the fluorescence quenching.

  4. Spectroscopic-ellipsometric study of native oxide removal by liquid phase HF process

    NASA Astrophysics Data System (ADS)

    Kurhekar, Anil Sudhakar; Apte, Prakash R.

    2013-02-01

    Ex situ spectroscopic ellipsometry (SE) measurements have been employed to investigate the effect of liquid-phase hydrofluoric acid (HF) cleaning on Si<100> surfaces for microelectromechanical systems application. The hydrogen terminated (H-terminated) Si surface was realized as an equivalent dielectric layer, and SE measurements are performed. The SE analyses indicate that after a 20-s 100:5 HF dip with rinse, the Si (100) surface was passivated by the hydrogen termination and remained chemically stable. Roughness of the HF-etched bare Si (100) surface was observed and analyzed by the ex-situ SE. Evidence for desorption of the H-terminated Si surface layer is studied using Fourier transform infrared spectroscopy and ellipsometry, and discussed. This piece of work explains the usage of an ex situ, non-destructive technique capable of showing state of passivation, the H-termination of Si<100> surfaces.

  5. Spectroscopic study of mixed oxide SAT 1- x:LA x perovskite crystals

    NASA Astrophysics Data System (ADS)

    Runka, T.; Łapsa, K.; Łapiński, A.; Aleksiyko, R.; Berkowski, M.; Drozdowski, M.

    2004-10-01

    Mixed perovskite crystals have been grown from multicomponent melts using the Czochralski method. The Raman, FT-IR and Brillouin investigations of perovskite (1- x)Sr(Al 0.5Ta 0.5)O 3: xLaAlO 3 crystals are reported. The measurements have been performed for several LA concentrations in the range 0.22≤ x≤0.36 at room temperature. The assignment of vibrational modes of IR and Raman spectra was proposed. The experimental results were correlated with structural data, obtained from X-ray diffraction study. The dependence of hypersonic velocity of transverse and longitudinal modes as a function of LA content was also determined. Spectroscopic investigations confirmed the disordered Al/Ta distribution, which increases with the increase of LA content.

  6. Spectroscopic studies of the physical origin of environmental aging effects on doped graphene

    NASA Astrophysics Data System (ADS)

    Chang, J.-K.; Hsu, C.-C.; Liu, S.-Y.; Wu, C.-I.; Gharib, M.; Yeh, N.-C.

    2016-06-01

    The environmental aging effect of doped graphene is investigated as a function of the organic doping species, humidity, and the number of graphene layers adjacent to the dopant by studies of the Raman spectroscopy, x-ray and ultraviolet photoelectron spectroscopy, scanning electron microscopy, infrared spectroscopy, and electrical transport measurements. It is found that higher humidity and structural defects induce faster degradation in doped graphene. Detailed analysis of the spectroscopic data suggest that the physical origin of the aging effect is associated with the continuing reaction of H2O molecules with the hygroscopic organic dopants, which leads to formation of excess chemical bonds, reduction in the doped graphene carrier density, and proliferation of damages from the graphene grain boundaries. These environmental aging effects are further shown to be significantly mitigated by added graphene layers.

  7. Spectroscopic analyses of Fe and water in clays: A Martian surface weathering study

    NASA Technical Reports Server (NTRS)

    Bishop, J. L.; Pieters, Carle M.; Edwards, J. O.; Coyne, L. M.; Chang, S.

    1991-01-01

    Martian surface morphology suggests the presence of liquid H2O on Mars in the past. Reflectance spectra of the Martian surface include features which correspond to the crystal field transitions of iron, as well as features supporting the presence of ice and minerals containing structural OH and surface water. Researchers initiated further spectroscopic studies of surface iron and water and structural OH in clays in order to determine what remotely obtained spectra can indicate about the presence of clays on Mars based on a clearer understanding of the factors influencing the spectral features. Current technology allows researchers to better correlate the low frequency fundamental stretching and bending vibrations of O-H bonds with the diagnostic near infrared overtone and combination bands used in mineral characterization and identification.

  8. Phosphorus-31 nuclear magnetic resonance spectroscopic study of the canine pancreas: applications to acute alcoholic pancreatitis

    SciTech Connect

    Janes, N.; Clemens, J.A.; Glickson, J.D.; Cameron, J.L.

    1988-01-01

    The first nuclear magnetic resonance spectroscopic study of the canine pancreas is described. Both in-vivo, ex-vivo protocols and NMR observables are discussed. The stability of the ex-vivo preparation based on the NMR observables is established for at least four hours. The spectra obtained from the in-vivo and ex-vivo preparations exhibited similar metabolite ratios, further validating the model. Metabolite levels were unchanged by a 50% increase in perfusion rate. Only trace amounts of phosphocreatine were observed either in the intact gland or in extracts. Acute alcoholic pancreatitis was mimicked by free fatty acid infusion. Injury resulted in hyperamylasemia, edema (weight gain), increased hematocrit and perfusion pressure, and depressed levels of high energy phosphates.

  9. [Monitoring cervical dilatation by impedance].

    PubMed

    Salvat, J; Lassen, M; Sauze, C; Baud, S; Salvat, F

    1992-01-01

    Several different physics procedures have been tried to mechanize the recording of partograms. Can a measure of impedance of tissue Z using potential difference V, according to Ohm's law V = Z1, and 1 is a constant, be correlated with a measure of cervical dilatation using vaginal examination? This was our hypothesis. The tissue impedance meter was made to our design and applied according to a bipolar procedure. Our work was carried out on 28 patients. 10 patients were registered before labour started in order to test the apparatus and to record the impedance variations without labour taking place, and 18 patients were registered in labour to see whether there was any correlation. The level of impedance in the cervix without labour was 302.7 Ohms with a deviation of 8.2. Using student's t tests it was found that there was a significant correlation (p less than 0.001) in four measurements between the impedance measure and measures obtained by extrapolating the degrees of dilatation calculated from vaginal examination. This is a preliminary study in which we have defined the conditions that are necessary to confirm these first results and to further develop the method. PMID:1401774

  10. An electrochemical study of corrosion protection by primer-topcoat systems on 4130 steel with ac impedance and dc methods

    NASA Technical Reports Server (NTRS)

    Mendrek, M. J.; Higgins, R. H.; Danford, M. D.

    1988-01-01

    To investigate metal surface corrosion and the breakdown of metal protective coatings, the ac impedance method is applied to six systems of primer coated and primer topcoated 4130 steel. Two primers were used: a zinc-rich epoxy primer and a red lead oxide epoxy primer. The epoxy-polyamine topcoat was used in four of the systems. The EG and G-PARC Model 368 ac impedance measurement system, along with dc measurements with the same system using the polarization resistance method, were used to monitor changing properties of coated 4230 steel disks immersed in 3.5 percent NaCl solutions buffered at pH 5.4 over periods of 40 to 60 days. The corrosion system can be represented by an electronic analog called an equivalent circuit consisting of resistors and capacitors in specific arrangements. This equivalent circuit parallels the impedance behavior of the corrosion system during a frequency scan. Values for the resistors and capacitors, that can be assigned in the equivalent circuit following a least-squares analysis of the data, describe changes that occur on the corroding metal surface and in the protective coatings. Two equivalent circuits have been determined that predict the correct Bode phase and magnitude of the experimental sample at different immersion times. The dc corrosion current density data are related to equivalent circuit element parameters. Methods for determining corrosion rate with ac impedance parameters are verified by the dc method.

  11. A photoelectron spectroscopic study of monovanadium oxide anions (VOx-, x=1-4)

    NASA Astrophysics Data System (ADS)

    Wu, Hongbin; Wang, Lai-Sheng

    1998-04-01

    We report on a photoelectron spectroscopic study of monovanadium oxides, VOx- (x=1-4), at four photon energies: 532, 355, 266, and 193 nm. Vibrationally resolved spectra are obtained for VO- at 532 and 355 nm detachment photon energies. Two new low-lying excited states are observed for VO at 5630 and 14 920 cm-1 above the ground state. These states are assigned to two doublet states, 2Σ- and 2Φ, respectively. The 532 and 355 nm spectra of VO2- reveal a single vibrational progression for the ground state with a frequency of 970 cm-1 (ν1). Three electronic excited states are observed for VO2 in the 193 nm spectrum. For VO3-, three surprisingly sharp detachment transitions are observed at 193 nm. The two excited states of VO3 are measured to be 0.59 and 0.79 eV above the ground state. The spectra of VO2- and VO3- are interpreted using the molecular-orbital schemes obtained in a recent ab initio theoretical study [Knight, Jr. et al., J. Chem. Phys. 105, 10237 (1996)], which predicts that both VO2 and VO3 neutrals are of C2v symmetry with a doublet ground state. The spectrum of VO4- is obtained at 193 nm, showing features similar to that of VO3-, but much more broadened. The adiabatic electron affinities of VO, VO2, VO3, and VO4 are measured to be 1.229 (8), 2.03 (1), 4.36 (5), and 4.0 (1) eV, respectively, with a significant increase from VO2 to VO3. The electronic and geometrical structures of the series of monovanadium oxide species are discussed based on the current observation and previous spectroscopic and theoretical results.

  12. Photophysics of α-furil at room temperature and 77 K: Spectroscopic and quantum chemical studies

    NASA Astrophysics Data System (ADS)

    Kundu, Pronab; Chattopadhyay, Nitin

    2016-06-01

    Steady state and time resolved spectroscopic measurements have been exploited to assign the emissions from different conformations of α-furil (2, 2'-furil) in solution phase at room temperature as well as cryogen (liquid nitrogen, LN2) frozen matrices of ethanol and methylcyclohexane. Room temperature studies reveal a single fluorescence from the trans-planar conformer of the fluorophore or two fluorescence bands coming from the trans-planar and the relaxed skew forms depending on excitation at the nπ∗ or the ππ∗ absorption band, respectively. Together with the fluorescence bands, the LN2 studies in both the solvents unambiguously ascertain two phosphorescence emissions with lifetimes 5 ± 0.3 ms (trans-planar triplet) and 81 ± 3 ms (relaxed skew triplet). Quantum chemical calculations have been performed using density functional theory at CAM-B3LYP/6-311++G∗∗ level to prop up the spectroscopic surveillance. The simulated potential energy curves (PECs) illustrate that α-furil is capable of giving two emissions from each of the S1 and the T1 states - one corresponding to the trans-planar and the other to the relaxed skew conformation. Contrary to the other 1,2-dicarbonyl molecular systems like benzil and α-naphthil, α-furil does not exhibit any fluorescence from its second excited singlet (S2) state. This is ascribed to the proximity of the minimum of the PEC of the S2 state and the hill-top of the PEC of the S1 state.

  13. Photophysics of α-furil at room temperature and 77 K: Spectroscopic and quantum chemical studies.

    PubMed

    Kundu, Pronab; Chattopadhyay, Nitin

    2016-06-21

    Steady state and time resolved spectroscopic measurements have been exploited to assign the emissions from different conformations of α-furil (2, 2'-furil) in solution phase at room temperature as well as cryogen (liquid nitrogen, LN2) frozen matrices of ethanol and methylcyclohexane. Room temperature studies reveal a single fluorescence from the trans-planar conformer of the fluorophore or two fluorescence bands coming from the trans-planar and the relaxed skew forms depending on excitation at the nπ(∗) or the ππ(∗) absorption band, respectively. Together with the fluorescence bands, the LN2 studies in both the solvents unambiguously ascertain two phosphorescence emissions with lifetimes 5 ± 0.3 ms (trans-planar triplet) and 81 ± 3 ms (relaxed skew triplet). Quantum chemical calculations have been performed using density functional theory at CAM-B3LYP/6-311++G(∗∗) level to prop up the spectroscopic surveillance. The simulated potential energy curves (PECs) illustrate that α-furil is capable of giving two emissions from each of the S1 and the T1 states-one corresponding to the trans-planar and the other to the relaxed skew conformation. Contrary to the other 1,2-dicarbonyl molecular systems like benzil and α-naphthil, α-furil does not exhibit any fluorescence from its second excited singlet (S2) state. This is ascribed to the proximity of the minimum of the PEC of the S2 state and the hill-top of the PEC of the S1 state. PMID:27334172

  14. Tailored Hospital-based Risk reduction to Impede Vascular Events after Stroke (THRIVES) study: qualitative phase protocol

    PubMed Central

    Owolabi, Mayowa O.; Akinyemi, Rufus O.; Hurst, Samantha; Arulogun, Oyedunni; Olaniyan, Olanrewaju; Gebregziabher, Mulugeta; Salako, Babatunde L.; Ovbiagele, Bruce

    2014-01-01

    Background There is an urgent need to develop effective strategies to improve stroke outcomes in Sub-Saharan Africa (SSA), where use of evidence-based therapies among patients receiving conventional care is poor. Designs of behavioral interventions to improve stroke care in SSA need to be sensitive to both individual and community factors (including local perceptions and public policies) contributing to the likelihood of compliance with recommended therapeutic goals. This article presents a community-based participatory research protocol that will evaluate systems and processes affecting the continuum of stroke preventive care in a SSA country. Methods/Design Phase 1 of the Tailored Hospital-based Risk Reduction to Impede Vascular Events (THRIVES) study will be implemented from 2013 to 2014 at four different types of hospital settings in Nigeria. Six adult stroke survivor and six stroke caregiver focus groups, comprising ~ 8 participants per group, and lasting 120 minutes each, will be conducted; as well as 22 semi-structured key informant interviews (informed by the Theoretical Domains Framework) with several types of providers and hospital administrators. Purposive and maximum variation sampling will be used to identify and recruit participants from participating hospitals. Transcript data will be analyzed by reviewers in an iterative process to identify recurrent and unifying themes using a constructivist variant of the grounded theory methodology, and will involve participatory co-analysis with key stakeholders to enhance authenticity and veracity of findings. Discussion Based on the results of THRIVES Phase 1, we intend to develop a culturally-sensitive, system-appropriate, multipronged intervention whose efficacy to boost adherence to evidence-based stroke preventive care will be tested in a future randomized trial (Phase 2). PMID:24526149

  15. Enhanced capacitance of composite TiO2 nanotube/boron-doped diamond electrodes studied by impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Siuzdak, K.; Bogdanowicz, R.; Sawczak, M.; Sobaszek, M.

    2014-12-01

    We report on novel composite nanostructures based on boron-doped diamond thin films grown on top of TiO2 nanotubes. The nanostructures made of BDD-modified titania nanotubes showed an increase in activity and performance when used as electrodes in electrochemical environments. The BDD thin films (~200-500 nm) were deposited using microwave plasma assisted chemical vapor deposition (MW PA CVD) onto anodically fabricated TiO2 nanotube arrays. The influence of boron-doping level, methane admixture and growth time on the performance of the Ti/TiO2/BDD electrode was studied in detail. Scanning electron microscopy (SEM) was applied to investigate the surface morphology and grain size distribution. Moreover, the chemical composition of TiO2/BDD electrodes was investigated by means of micro-Raman spectroscopy. The composite electrodes TiO2/BDD are characterized by a significantly higher capacitive current compared to BDD films deposited directly onto a Ti substrate. The novel composite electrode of TiO2 nanotube arrays overgrown by boron-doped diamond (BDD) immersed in 0.1 M NaNO3 can deliver a specific capacitance of 2.10, 4.79, and 7.46 mF cm-2 at a scan rate of 10 mV s-1 for a [B]/[C] ratio of 2k, 5k and 10k, respectively. The substantial improvement of electrochemical performance and the excellent rate capability could be attributed to the synergistic effect of TiO2 treatment in CH4 : H2 plasma and the high electrical conductivity of BDD layers. The analysis of electrochemical impedance spectra using an electric equivalent circuit allowed us to determine the surface area on the basis of the value of constant phase element.

  16. Coupled cluster study of spectroscopic constants of ground states of heavy rare gas dimers with spin-orbit interaction

    NASA Astrophysics Data System (ADS)

    Tu, Zhe-Yan; Wang, Wen-Liang; Li, Ren-Zhong; Xia, Cai-Juan; Li, Lian-Bi

    2016-07-01

    The CCSD(T) approach based on two-component relativistic effective core potential with spin-orbit interaction just included in coupled cluster iteration is adopted to study the spectroscopic constants of ground states of Kr2, Xe2 and Rn2 dimers. The spectroscopic constants have significant basis set dependence. Extrapolation to the complete basis set limit provides the most accurate values. The spin-orbit interaction hardly affects the spectroscopic constants of Kr2 and Xe2. However, the equilibrium bond length is shortened about 0.013 Å and the dissociation energy is augmented about 18 cm-1 by the spin-orbit interaction for Rn2 in the complete basis set limit.

  17. Chemical, spectroscopic characterization, DFT studies and antibacterial activities in vitro of a new gold(I) complex with rimantadine.

    PubMed

    Sucena, Suelen F; Paiva, Raphael E F; Abbehausen, Camilla; Mattos, Ives B; Lancellotti, Marcelo; Formiga, André L B; Corbi, Pedro P

    2012-04-01

    A novel gold(I) complex with rimantadine (RTD) was obtained and structurally characterized by a set of chemical and spectroscopic analysis. 1H, 13C and 15N nuclear magnetic resonance (NMR) and infrared (IR) spectroscopic measurements suggest coordination of the ligand to Au(I) through the N atom of the ethanamine group. Theoretical (DFT) calculations confirmed the IR assignments and permit proposing an optimized geometry for the complex. The gold(I)-rimantadine complex (Au-RTD) is soluble in methanol, ethanol, dimethylsulfoxide, acetone and acetonitrile. The preliminary kinetic studies based on UV-vis spectroscopic measurements indicate the stability of the compound in solution. Antibacterial activities of the complex were evaluated by an antibiogram assay. The Au-RTD complex showed an effective in vitro antibacterial activity against the Pseudomonas aeruginosa, Escherichia coli (Gram-negative), and Staphylococcus aureus (Gram-positive) bacterial strains. PMID:22257715

  18. Spectroscopic study of gold nanoparticle formation through high intensity laser irradiation of solution

    SciTech Connect

    Nakamura, Takahiro Sato, Shunichi; Herbani, Yuliati; Ursescu, Daniel; Banici, Romeo; Dabu, Razvan Victor

    2013-08-15

    A spectroscopic study of the gold nanoparticle (NP) formation by high-intensity femtosecond laser irradiation of a gold ion solution was reported. The effect of varying energy density of the laser on the formation of gold NPs was also investigated. The surface plasmon resonance (SPR) peak of the gold nanocolloid in real-time UV-visible absorption spectra during laser irradiation showed a distinctive progress; the SPR absorption peak intensity increased after a certain irradiation time, reached a maximum and then gradually decreased. During this absorption variation, at the same time, the peak wavelength changed from 530 to 507 nm. According to an empirical equation derived from a large volume of experimental data, the estimated mean size of the gold NPs varied from 43.4 to 3.2 nm during the laser irradiation. The mean size of gold NPs formed at specific irradiation times by transmission electron microscopy showed the similar trend as that obtained in the spectroscopic analysis. From these observations, the formation mechanism of gold NPs during laser irradiation was considered to have two steps. The first is a reduction of gold ions by reactive species produced through a non-linear reaction during high intensity laser irradiation of the solution; the second is the laser fragmentation of produced gold particles into smaller pieces. The gold nanocolloid produced after the fragmentation by excess irradiation showed high stability for at least a week without the addition of any dispersant because of the negative charge on the surface of the nanoparticles probably due to the surface oxidation of gold nanoparticles. A higher laser intensity resulted in a higher efficiency of gold NPs fabrication, which was attributed to a larger effective volume of the reaction.

  19. Spectroscopic and theoretical studies on the excited state in diimine dithiolate complexes of platinum(II)

    SciTech Connect

    Zuleta, J.A.; Bevilacqua, J.M.; Eisenberg, R. ); Proserpio, D.M. ); Harvey, P.D. )

    1992-06-10

    The photophysical properties of a series of Pt(N-N)(S-S) complexes have been studied where (N-N) is either an [alpha],[alpha][prime]-diimine or saturated diamine chelating ligand and (S-S) is either a dithiolate chelating ligand or two monothiolate ligands in order to determine the orbital composition of the excited state. The solvent dependence of the absorption spectra of these complexes and the temperature dependence of their emission intensities and lifetimes have been examined while the ligands have been systematically varied. The electronic spectra are found to be dependent on whether or not the nitrogen chelating ligand is unsaturated (contains a vacant [pi]* orbital). On the basis of the spectroscopic data, the lowest energy absorption band in the diimine complexes is assigned as a metal-dithiolate to [pi]*(diimine) transition, whereas in the diamine complexes it is assigned as a metal-to-dithiolate MLCT transition. The only room-temperature emissive complexes are those that contain an [alpha],[alpha][prime]-diimine chelating ligand. The nature of the emission in these complexes at all temperatures depends on the dithiolate ligand, and the temperature dependence of the emission spectra has been examined. The nature of the HOMO and LUMO has been examined experimentally using cyclic voltammetry. On the basis of the electrochemical and spectroscopic data, the emission from all of the Pt(diimine)(S-S) complexes except those of 1,2-dithiolate maleonitriledithiolate (mnt) is assigned as a [sup 3](d(Pt)/p(S)-[pi]*(diimine)) transition, while, for the mnt complexes, it corresponds to a [sup 3](d(Pt)/p(S)-[pi]*(mnt)) transition. These assignments are supported by extended Hueckel molecular orbital calculations.

  20. Study on the interaction of catechins with human serum albumin using spectroscopic and electrophoretic techniques

    NASA Astrophysics Data System (ADS)

    Trnková, Lucie; Boušová, Iva; Staňková, Veronika; Dršata, Jaroslav

    2011-01-01

    The interaction between eight naturally occurring flavanols (catechin, epicatechin, gallocatechin, epigallocatechin, catechin gallate, epicatechin gallate, gallocatechin gallate, and epigallocatechin gallate) and human serum albumin (HSA) has been investigated by spectroscopic (fluorescence quenching and UV-Vis absorption) and electrophoretic (native and SDS PAGE) techniques under simulated physiological conditions (pH 7.40, 37 °C). The spectroscopic results confirmed the complex formation for the tested systems. The binding constants and the number of binding sites were obtained by analysis of fluorescence data. The strongest binding affinity to HSA was found for epicatechin gallate and decreased in the order epicatechin gallate ⩾ catechin gallate > epigallocatechin gallate > gallocatechin gallate ≫ epicatechin ⩾ catechin > gallocatechin ⩾ epigallocatechin. All free energy changes possessed negative sign indicating the spontaneity of catechin-HSA systems formation. The binding distances between the donor (HSA) and the acceptors (catechins) estimated by the Förster theory revealed that non-radiation energy transfer from HSA to catechins occurred with high possibility. According to results obtained by native PAGE, the galloylated catechins increased the electrophoretic mobility of HSA, which indicated the change in the molecular charge of HSA, whilst the non-galloylated catechins caused no changes. The ability of aggregation and cross-linking of tested catechins with HSA was not proved by SDS-PAGE. The relationship between the structure characteristics of all tested catechins (e.g. presence of the galloyl moiety on the C-ring, the number of hydroxyl groups on the B-ring, and the spatial arrangement of the substituents on the C-ring) and their binding properties to HSA is discussed. The presented study contributes to the current knowledge in the area of protein-ligand binding, particularly catechin-HSA interactions.

  1. Crystallographic, kinetic, and spectroscopic study of the first ligninolytic peroxidase presenting a catalytic tyrosine.

    PubMed

    Miki, Yuta; Calviño, Fabiola R; Pogni, Rebecca; Giansanti, Stefania; Ruiz-Dueñas, Francisco J; Martínez, María Jesús; Basosi, Riccardo; Romero, Antonio; Martínez, Angel T

    2011-04-29

    Trametes cervina lignin peroxidase (LiP) is a unique enzyme lacking the catalytic tryptophan strictly conserved in all other LiPs and versatile peroxidases (more than 30 sequences available). Recombinant T. cervina LiP and site-directed variants were investigated by crystallographic, kinetic, and spectroscopic techniques. The crystal structure shows three substrate oxidation site candidates involving His-170, Asp-146, and Tyr-181. Steady-state kinetics for oxidation of veratryl alcohol (the typical LiP substrate) by variants at the above three residues reveals a crucial role of Tyr-181 in LiP activity. Moreover, assays with ferrocytochrome c show that its ability to oxidize large molecules (a requisite property for oxidation of the lignin polymer) originates in Tyr-181. This residue is also involved in the oxidation of 1,4-dimethoxybenzene, a reaction initiated by the one-electron abstraction with formation of substrate cation radical, as described for the well known Phanerochaete chrysosporium LiP. Detailed spectroscopic and kinetic investigations, including low temperature EPR, show that the porphyrin radical in the two-electron activated T. cervina LiP is unstable and rapidly receives one electron from Tyr-181, forming a catalytic protein radical, which is identified as an H-bonded neutral tyrosyl radical. The crystal structure reveals a partially exposed location of Tyr-181, compatible with its catalytic role, and several neighbor residues probably contributing to catalysis: (i) by enabling substrate recognition by aromatic interactions; (ii) by acting as proton acceptor/donor from Tyr-181 or H-bonding the radical form; and (iii) by providing the acidic environment that would facilitate oxidation. This is the first structure-function study of the only ligninolytic peroxidase described to date that has a catalytic tyrosine. PMID:21367853

  2. A study of non-Keplerian velocities in observations of spectroscopic binary stars

    NASA Astrophysics Data System (ADS)

    Hearnshaw, J. B.; Komonjinda, Siramas; Skuljan, J.; Kilmartin, P. M.

    2012-11-01

    This paper presents an orbital analysis of six southern single-lined spectroscopic binary systems. The systems selected were shown to have circular or nearly circular orbits (e < 0.1) from earlier published solutions of only moderate precision. The purpose was to obtain high-precision orbital solutions in order to investigate the presence of small non-Keplerian velocity effects in the data and hence the reality of the small eccentricities found for most of the stars. The Hercules spectrograph and 1-m McLellan telescope at Mt John Observatory, New Zealand, were used to obtain over 450 CCD spectra between 2004 October and 2007 August. Radial velocities were obtained by cross-correlation. These data were used to achieve high-precision orbital solutions for all the systems studied, sometimes with solutions up to about 50 times more precise than those from the earlier literature. However, the precision of the solutions is limited in some cases by the rotational velocity or chromospheric activity of the stars. The data for the six binaries analysed here are combined with those for six stars analysed earlier by Komonjinda, Hearnshaw and Ramm. We have performed tests using the prescription of Lucy on all 12 binaries, and conclude that, with one exception, none of the small eccentricities found by fitting Keplerian orbits to the radial-velocity data can be supported. Instead we conclude that small non-Keplerian effects, which are clearly detectable for six of our stars, make impossible the precise determination of spectroscopic binary orbital eccentricities for many late-type stars to better than about 0.03 in eccentricity, unless the systematic perturbations are also carefully modelled. The magnitudes of the non-Keplerian velocity variations are given quantitatively.

  3. Impedance of a nanoantenna

    SciTech Connect

    Greffet, Jean-Jacques; Laroche, Marine; Marquier, Francois

    2009-10-07

    We introduce a generalized definition of the impedance of a nanoantenna that can be applied to any system. We also introduce a definition of the impedance of a two level system. Using this framework, we establish a link between the electrical engineering and the quantum optics picture of light emission.

  4. Millimeter-Wave Spectroscopic and Collisional Studies of Molecules and Molecular Ions

    NASA Astrophysics Data System (ADS)

    Pearson, John Christoffersen

    1995-01-01

    Molecular spectroscopy in the millimeter- and submillimeter-wave regions is an important tool in molecular physics. Information on molecular motions and interactions is obtained from spectroscopic studies of energy levels and collisions. This information and the data from which it is derived are essential in remote sensing of the atmosphere and the interstellar medium. Remote sensing at submillimeter wavelengths is now possible, making higher frequency and quantum number measurements of known interstellar species like water, propionitrile and ethyl alcohol necessary. Remote sensing improvements have also facilitated the need for spectral data on suspected interstellar molecules like propylene. The desire to extract quantitative information from atmospheric remote sensing has resulted in the need for a better understanding of the molecular interactions that cause pressure broadening. The use of a cold molecular ion to magnify the effects of intermolecular interactions has serious implications for pressure broadening theory. The measurement and analysis of rotational spectra of the asymmetric rotors water and propionitrile and the internal rotors propylene and ethyl alcohol are presented. These investigations provide the data and analysis necessary for astronomical observation. The ethyl alcohol investigation is the first experimental millimeter-wave study of a molecule with an asymmetric internal rotor. This study provides the data necessary for detailed theoretical modeling of this type of problem. A novel new experimental technique for generating and studying molecular ions is presented. The first temperature dependent microwave pressure broadening study of a molecular ion colliding with a neutral molecule, HCO^{+} on H_2 , is presented.

  5. Effect of low-temperature conditions on passive layer growth in Li intercalation materials: In situ impedance study

    SciTech Connect

    Barsoukov, E.; Kim, J.H.; Kim, J.H.; Yoon, C.O.; Lee, H.

    1998-08-01

    Electrochemical impedance spectroscopy has been applied to investigate the formation of insulating layers at the surfaces of microscopic particles of mesocarbon microbeads (MCMB), graphite, and hard carbon during the first Li-intercalation into these materials at ambient temperature as well as at {minus}20 C. Investigations were carried out in a three-electrode sandwich cell, designed for impedance measurements in the frequency range 64 kHz to 5 mHz. The impedance spectra, obtained in the potential range 1.5 and 0.02 V during the first charge, were analyzed by complex nonlinear least square fits. A new model, taking into account the porous structure of the intercalation material, electrochemical processes at the interface, as well as spherical diffusion of Li ions toward the centers of the particles, has been used for this analysis. The first intercalation at {minus}20 C results in formation of an insulating layer, which is about 90 times thinner than in the room-temperature case, as concluded from an analysis of experimental results. The irreversible capacity loss, which is 1.3 times larger at {minus}20 C that at room temperature, is ascribed to the formation of a porous precipitate of electrolyte decomposition products on the particle surface. Additional Li intercalation at room temperature results in an irreversible capacity loss of 26% from the initial value, and formation of a composite layer, including low-temperature and room-temperature deposited components.

  6. Spectroscopic studies of interaction between CuO nanoparticles and bovine serum albumin.

    PubMed

    Esfandfar, Paniz; Falahati, Mojtaba; Saboury, AliAkbar

    2016-09-01

    Recently, the great interests in manufacturing and application of metal oxide nanoparticles in commercial and industrial products have led to focus on the potential impact of these particles on biomacromolecules. In the present study, the interaction of copper oxide (CuO) nanoparticles with bovine serum albumin (BSA) was studied by spectroscopic techniques. The zeta potential value for BSA and CuO nanoparticles with average diameter of around 50 nm at concentration of 10 μM in the deionized (DI) water were -5.8 and -22.5 mV, respectively. Circular dichroism studies did not show any changes in the content of secondary structure of the protein after CuO nanoparticles interaction. Fluorescence data revealed that the fluorescence quenching of BSA by CuO nanoparticles was the result of the formed complex of CuO nanoparticles - BSA. Binding constants and other thermodynamic parameters were determined at three different temperatures. The hydrogen bond interactions are the predominant intermolecular forces to stabilize the CuO nanoparticle - BSA complex. This study provides important insight into the interaction of CuO nanoparticles with proteins, which may be of importance for further application of these nanoparticles in biomedical applications. PMID:26555383

  7. UV-visible and (1)H-(15)N NMR spectroscopic studies of colorimetric thiosemicarbazide anion sensors.

    PubMed

    Farrugia, Kristina N; Makuc, Damjan; Podborska, Agnieszka; Szaciłowski, Konrad; Plavec, Janez; Magri, David C

    2015-02-14

    Four model thiosemicarbazide anion chemosensors containing three N-H bonds, substituted with phenyl and/or 4-nitrophenyl units, were synthesised and studied for their anion binding abilities with hydroxide, fluoride, acetate, dihydrogen phosphate and chloride. The anion binding properties were studied in DMSO and 9 : 1 DMSO-H2O by UV-visible absorption and (1)H/(13)C/(15)N NMR spectroscopic techniques and corroborated with DFT studies. Significant changes were observed in the UV-visible absorption spectra with all anions, except for chloride, accompanied by dramatic colour changes visible to the naked eye. These changes were determined to be due to the deprotonation of the central N-H proton and not due to hydrogen bonding based on (1)H/(15)N NMR titration studies with acetate in DMSO-d6-0.5% water. Direct evidence for deprotonation was confirmed by the disappearance of the central thiourea proton and the formation of acetic acid. DFT and charge distribution calculations suggest that for all four compounds the central N-H proton is the most acidic. Hence, the anion chemosensors operate by a deprotonation mechanism of the central N-H proton rather than by hydrogen bonding as is often reported. PMID:25451865

  8. Spectroscopic studies on diamond like carbon films synthesized by pulsed laser ablation

    NASA Astrophysics Data System (ADS)

    Panda, Madhusmita; Krishnan, R.; Ravindran, T. R.; Das, Arindam; Mangamma, G.; Dash, S.; Tyagi, A. K.

    2016-05-01

    Hydrogen free Diamond like Carbon (DLC) thin films enriched with C-C sp3 bonding were grown on Si (111) substrates at laser pulse energies varying from 100 to 400 mJ (DLC-100, DLC-200, DLC-300, DLC-400), by Pulsed Laser Ablation (PLA) utilizing an Nd:YAG laser operating at fundamental wavelength. Structural, optical and morphological evolutions as a function of laser pulse energy were studied by micro Raman, UV-Vis spectroscopic studies and Atomic Force Microscopy (AFM), respectively. Raman spectra analysis provided critical clues for the variation in sp3 content and optical energy gap. The sp3 content was estimated using the FWHM of the G peak and found to be in the range of 62-69%. The trend of evolution of sp3 content matches well with the evolution of ID/IG ratio with pulse energy. UV-Vis absorption study of DLC films revealed the variation of optical energy gap with laser pulse energy (1.88 - 2.23 eV), which matches well with the evolution of G-Peak position of the Raman spectra. AFM study revealed that roughness, size and density of particulate in DLC films increase with laser pulse energy.

  9. Studies of the Use of Electrochemical Impedance Spectroscopy to Characterize and Assess the Performance of Lacquers Used to Protect Aluminum Sheet and Can Ends

    NASA Astrophysics Data System (ADS)

    Ali, Mohammad

    This study involved investigating the feasibility of using Electrochemical Impedance Spectroscopy to assess the performance of coatings used to protect aluminum in beverage containers, and developing an accelerated testing procedure. In the preliminary investigation, tests were performed to ensure that the EIS systems at hand are capable, functional and consistent. This was followed by EIS testing of kitchen-aluminum foil and high-impedance epoxy polymer as a baseline for chemically-active and chemically-inert systems. The ability of EIS to differentiate between intact and flawed coatings was tested by investigating deliberately damaged coatings. The effects of varying the pH and oxygen content on the performance of the coated aluminum samples were also tested. From this investigation, it has been concluded that EIS can be used to differentiate between intact and flawed coatings and detect corrosion before it is visually observable. Signatures of corrosion have been recorded and a preliminary testing procedure has been drawn.

  10. Overview Of Impedance Sensors

    NASA Astrophysics Data System (ADS)

    Abele, John E.

    1989-08-01

    Electrical impedance has been one of the many "tools of great promise" that physicians have employed in their quest to measure and/or monitor body function or physiologic events. So far, the expectations for its success have always exceeded its performance. In simplistic terms, physiologic impedance is a measure of the resistance in the volume between electrodes which changes as a function of changes in that volume, the relative impedance of that volume, or a combination of these two. The history and principles of electrical impedance are very nicely reviewed by Geddes and Baker in their textbook "Principles of Applied Biomedical Instrumentation". It is humbling, however, to note that Cremer recorded variations in electrical impedance in frog hearts as early as 1907. The list of potential applications includes the measurement of thyroid function, estrogen activity, galvanic skin reflex, respiration, blood flow by conductivity dilution, nervous activity and eye movement. Commercial devices employing impedance have been and are being used to measure respiration (pneumographs and apneamonitors), pulse volume (impedance phlebographs) and even noninvasive cardiac output.

  11. Emerging trends in X-ray spectroscopic studies of plasma produced by intense laser beams

    SciTech Connect

    Arora, V.; Chakera, J. A.; Naik, P. A.; Gupta, P. D.

    2015-07-31

    X-ray line emission from hot dense plasmas, produced by ultra-short high intensity laser systems, has been studied experimentally in recent years for applications in materials science as well as for back-lighter applications. By virtue of the CPA technology, several laser facilities delivering pulses with peak powers in excess of one petawatt (focused intensities > 10{sup 20} W-cm{sup −2}) have either been commissioned across the globe during the last few years or are presently under construction. On the other hand, hard x-ray sources on table top, generating ultra-short duration x-rays at a repetition rate up to 10 kHz, are routinely available for time resolved x-ray diffraction studies. In this paper, the recent experiments on x-ray spectroscopic studies of plasma produced by 45 fs, Ti:sapphire laser pulses (focused iintensity > 10{sup 18} W-cm{sup −2}) at RRCAT Indore will be presented.

  12. Spectroscopic studies on sidewall carboxylic acid functionalization of multi-walled carbon nanotubes with valine

    NASA Astrophysics Data System (ADS)

    Deborah, M.; Jawahar, A.; Mathavan, T.; Dhas, M. Kumara; Benial, A. Milton Franklin

    2015-03-01

    The valine functionalized multi-walled carbon nanotubes (MWCNTS) were prepared and characterized by using XRD, UV-Vis, FT-IR, EPR, SEM, and EDX, spectroscopic techniques. The enhanced XRD peak (0 0 2) intensity was observed for valine functionalized MWCNTs compared with oxidized MWCNTs, which is likely due to sample purification by acid washing. UV-Vis study shows the formation of valine functionalized MWCNTs. FT-IR study confirms the presence of functional groups of oxidized MWCNTs and valine functionalized MWCNTs. The ESR line shape analysis indicates that the observed EPR line shape is a Gaussian line shape. The g-values indicate that the systems are isotropic in nature. The morphology study was carried out for oxidized MWCNTs and valine functionalized MWCNTs by using SEM. The EDX spectra revealed that the high purity of oxidized MWCNTs and valine functionalized MWCNTs. The functionalization has been chosen because, functionalization of CNTs with amino acids makes them soluble and biocompatible. Thus, they have potential applications in the field of biosensors and targeted drug delivery.

  13. Raman spectroscopic study of keratin 8 knockdown oral squamous cell carcinoma derived cells

    NASA Astrophysics Data System (ADS)

    Singh, S. P.; Alam, Hunain; Dmello, Crismita; Vaidya, Milind M.; Krishna, C. Murali

    2012-03-01

    Keratins are one of most widely used markers for oral cancers. Keratin 8 and 18 are expressed in simple epithelia and perform both mechanical and regulatory functions. Their expression are not seen in normal oral tissues but are often expressed in oral squamous cell carcinoma. Aberrant expression of keratins 8 and 18 is most common change in human oral cancer. Optical-spectroscopic methods are sensitive to biochemical changes and being projected as novel diagnostic tools for cancer diagnosis. Aim of this study was to evaluate potentials of Raman spectroscopy in detecting minor changes associated with differential level of keratin expression in tongue-cancer-derived AW13516 cells. Knockdown clones for K8 were generated and synchronized by growing under serum-free conditions. Cell pellets of three independent experiments in duplicate were used for recording Raman spectra with fiberoptic-probe coupled HE-785 Raman-instrument. A total of 123 and 96 spectra from knockdown clones and vector controls respectively in 1200-1800 cm-1 region were successfully utilized for classification using LDA. Two separate clusters with classification-efficiency of ~95% were obtained. Leave-one-out cross-validation yielded ~63% efficiency. Findings of the study demonstrate the potentials of Raman spectroscopy in detecting even subtle changes such as variations in keratin expression levels. Future studies towards identifying Raman signals from keratin in oral cells can help in precise cancer diagnosis.

  14. Spectroscopic studies of the progress of humification processes in humic acid extracted from sewage sludge

    NASA Astrophysics Data System (ADS)

    Polak, J.; Sułkowski, W. W.; Bartoszek, M.; Papież, W.

    2005-06-01

    The humic acids extracted from sludge collected from the digestion chamber and the sludge drying beds were studied. The sludge samples were collected, dried and humic acids were extracted. The progress of the humification processes was studied with EPR, IR and NMR spectroscopic methods. For extracted humic acids, concentration of free radicals and g factor was determined with EPR. The presence of characteristic functional groups was confirmed with IR and NMR spectroscopy. To study the changes in content of the elements, the elemental analysis was performed to determine the percentage of carbon, hydrogen, nitrogen, sulfur and oxygen. Taking all the obtained results into account it was found that on the sewage drying beds, humification processes take place in the sludge. In the first two weeks when the sludge on the drying beds an intensive enrichment of humic acids in free radicals takes place. This is the result of the intensive humification process course after the stage in the fermentation chamber where the mesophilic fermentation takes place. Moreover, the humidity of sludge influences the intensive development of free radical concentration at the beginning of the storing period, whereas the humification processes still continue.

  15. Spectroscopic study of formation, evolution and interaction of M31 and M33 with star clusters

    NASA Astrophysics Data System (ADS)

    Fan, Zhou; Yang, Yanbin

    2016-02-01

    The recent studies show that the formation and evolution process of the nearby galaxies are still unclear. By using the Canada France Hawaii Telescope (CFHT) 3.6m telescope, the PanDAS shows complicated substructures (dwarf satellite galaxies, halo globular clusters, extended clusters, star streams, etc.) in the halo of M31 to ~150 kpc from the center of galaxy and M31-M33 interaction has been studied. In our work, we would like to investigate formation, evolution and interaction of M31 and M33, which are the nearest two spiral galaxies in Local Group. The star cluster systems of the two galaxies are good tracers to study the dynamics of the substructures and the interaction. Since 2010, the Xinglong 2.16m, Lijiang 2.4m and MMT 6.5m telescopes have been used for our spectroscopic observations. The radial velocities and Lick absorption-line indices can thus be measured with the spectroscopy and then ages, metallicities and masses of the star clusters can be fitted with the simple stellar population models. These parameters could be used as the input physical parameters for numerical simulations of M31-M33 interaction.

  16. Spectroscopic studies on sidewall carboxylic acid functionalization of multi-walled carbon nanotubes with valine.

    PubMed

    Deborah, M; Jawahar, A; Mathavan, T; Dhas, M Kumara; Benial, A Milton Franklin

    2015-03-15

    The valine functionalized multi-walled carbon nanotubes (MWCNTS) were prepared and characterized by using XRD, UV-Vis, FT-IR, EPR, SEM, and EDX, spectroscopic techniques. The enhanced XRD peak (002) intensity was observed for valine functionalized MWCNTs compared with oxidized MWCNTs, which is likely due to sample purification by acid washing. UV-Vis study shows the formation of valine functionalized MWCNTs. FT-IR study confirms the presence of functional groups of oxidized MWCNTs and valine functionalized MWCNTs. The ESR line shape analysis indicates that the observed EPR line shape is a Gaussian line shape. The g-values indicate that the systems are isotropic in nature. The morphology study was carried out for oxidized MWCNTs and valine functionalized MWCNTs by using SEM. The EDX spectra revealed that the high purity of oxidized MWCNTs and valine functionalized MWCNTs. The functionalization has been chosen because, functionalization of CNTs with amino acids makes them soluble and biocompatible. Thus, they have potential applications in the field of biosensors and targeted drug delivery. PMID:25554963

  17. Structural studies of E. coli ribosomes by spectroscopic techniques: A specialized review

    NASA Astrophysics Data System (ADS)

    Bonicontro, Adalberto; Risuleo, Gianfranco

    2005-12-01

    We present a review on our interdisciplinary line of research based on strategies of molecular biology and biophysics. These have been applied to the study of the prokaryotic ribosome of the bacterium Escherichia coli. Our investigations on this organelle have continued for more than a decade and we have adopted different spectroscopic biophysical techniques such as: dielectric and fluorescence spectroscopy as well as light scattering (photon correlation spectroscopy). Here we report studies on the whole 70S ribosomes and on the separated subunits 30S and 50S. Our results evidence intrinsic structural features of the subunits: the small shows a more "floppy" structure, while the large one appears to be more rigid. Also, an inner "kernel" formed by the RNA/protein association is found within the ribosome. This kernel is surrounded by a ribonucleoprotein complex more exposed to the solvent. Initial analyses were done on the so called Kaldtschmit-Wittmann ribosome: more recently we have extended the studies to the "tight couple" ribosome known for its better functional performance in vitro. Data evidence a phenomenological correlation between the differential biological activity and the intrinsic structural properties of the two-ribosome species. Finally, investigations were also conducted on particles treated at sub-denaturing temperatures and on ribosomes partially deproteinized by salt treatment (ribosomal cores). Results suggest that the thermal treatment and the selective removal of proteins cause analogous structural alterations.

  18. [Spectroscopic studies on the binding of phenazopyridine hydrochloride and bovine serum albumin].

    PubMed

    Zhou, Hong; Chen, Chang-Yun; Xie, An-Jian

    2007-09-01

    The binding of phenazopyridine hydrochloride and bovine serum albumin under physiological conditions was studied by spectroscopic method. The quenching mechanism of the fluorescence of bovine serum albumin by phenazopyridine hydrochloride was studied with fluorescence and absorption spectroscopy. The binding constant Kb and the number of binding sites n were determined at different temperatures according to Scatchard equation, and the main binding force was discussed by thermodynamic equations. The effect of the drug on bovine serum albumin conformation was also studied by using synchronous fluorescence spectroscopy. The quenching mechanism of phenazopyridine hydrochloride to bovine serum albumin is static quenching and non-radiation energy transfer. The binding constants Kb at 15, 25 and 37 degrees C are 2.47 x 10(7), 9.15 x 10(6) and 4.36 x 10(6) mol(-1) with one binding site, respectively. The thermodynamic parameters of the reaction are DeltaH = -71.2 kJ x mol(-1), and DeltaS = 124.8 J x mol(-1) x K(-1). Binding phenazopyridine hydrochloride to bovine serum albumin is a spontaneous inter-molecular interaction in which entropy increases and Gibbs free energy decreases. The binding distance r between phenazopyridine hydrochloride and bovine serum albumin is 1.61 nm according to Forster theory of non-radiation energy transfer. The binding force is electrostatic interaction. Phenazopyridine hydrochloride can be deposited and transported by serum protein in vivo. Phenazopyridine hydrochloride does affect the serum protein conformation. PMID:18051539

  19. Fourier Transform Infrared Spectroscopic Studies on Modulation of N-Nitrosodiethylamine-Induced Hepatocarcinogenesis by Azadirachta indica.

    PubMed

    Bharati, Sanjay; Rishi, Parveen; Koul, Ashwani

    2015-01-01

    Fourier transform infrared spectroscopy was employed in the present study to obtain information about the molecular composition of hepatic tumor versus hepatic tissue. A hepatic cancer model was developed by administering N-nitrosodiethylamine (NDEA) to male Balb/c mice. The results revealed that NDEA-induced hepatic cancer tumor tissue had altered molecular composition compared with normal liver tissue. Compared with the normal tissue, the saturation level of membrane phospholipids was observed to be decreased in tumors along with an abnormal distribution of protein secondary structures. A significant decrease in glycogen and a significant increase in total nucleic acid content were also observed in tumor cells. The administration of aqueous Azadirachta indica leaf extract (AAILE) prior to NDEA treatment resulted in the normalization of saturation levels in phospholipids and total nucleic acid content and in the distribution of protein secondary structures in tumors. A significant increase in the amount of stored glycogen was observed in AAILE cotreated tumors compared with NDEA-induced tumors, which might indicate that AAILE cotreatment impeded the ability of tumor cells to consume glucose at a faster rate. The normalization of molecular composition upon AAILE cotreatment in hepatic tumors might indicate that AAILE hampered the process of evolution of tumors, which could be responsible for its observed chemopreventive action. PMID:26349605

  20. Microfabricated AC impedance sensor

    DOEpatents

    Krulevitch, Peter; Ackler, Harold D.; Becker, Frederick; Boser, Bernhard E.; Eldredge, Adam B.; Fuller, Christopher K.; Gascoyne, Peter R. C.; Hamilton, Julie K.; Swierkowski, Stefan P.; Wang, Xiao-Bo

    2002-01-01

    A microfabricated instrument for detecting and identifying cells and other particles based on alternating current (AC) impedance measurements. The microfabricated AC impedance sensor includes two critical elements: 1) a microfluidic chip, preferably of glass substrates, having at least one microchannel therein and with electrodes patterned on both substrates, and 2) electrical circuits that connect to the electrodes on the microfluidic chip and detect signals associated with particles traveling down the microchannels. These circuits enable multiple AC impedance measurements of individual particles at high throughput rates with sufficient resolution to identify different particle and cell types as appropriate for environmental detection and clinical diagnostic applications.

  1. Near infrared photometric and optical spectroscopic study of 22 low mass star clusters embedded in nebulae

    NASA Astrophysics Data System (ADS)

    Soares, J. B.; Bica, E.; Ahumada, A. V.; Clariá, J. J.

    2008-02-01

    Aims:Among the star clusters in the Galaxy, those embedded in nebulae represent the youngest group, which has only recently been explored. The analysis of a sample of 22 candidate embedded stellar systems in reflection nebulae and/or HII environments is presented. Methods: We employed optical spectroscopic observations of stars in the directions of the clusters carried out at CASLEO (Argentina) together with near infrared photometry from the 2MASS catalogue. Our analysis is based on source surface density, colour-colour diagrams and on theoretical pre-main sequence isochrones. We take into account the field star contamination by carrying out a statistical subtraction. Results: The studied objects have the characteristics of low mass systems. We derive their fundamental parameters. Most of the cluster ages are younger than 2 Myr. The studied embedded stellar systems in reflection nebulae and/or HII region complexes do not have stars of spectral types earlier than B. The total stellar masses locked in the clusters are in the range 20-220 M⊙. They are found to be gravitationally unstable and are expected to dissolve in a timescale of a few Myr. Based on observations made at Complejo Astronómico El Leoncito, which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba and San Juan, Argentina.

  2. Optical and spectroscopic studies on tannery wastes as a possible source of organic semiconductors.

    PubMed

    Nashy, El-Shahat H A; Al-Ashkar, Emad; Moez, A Abdel

    2012-02-01

    Tanning industry produces a large quantity of solid wastes which contain hide proteins in the form of protein shavings containing chromium salts. The chromium wastes are the main concern from an environmental stand point of view, because chrome wastes posses a significant disposal problem. The present work is devoted to investigate the possibility of utilizing these wastes as a source of organic semi-conductors as an alternative method instead of the conventional ones. The chemical characterization of these wastes was determined. In addition, the Horizontal Attenuated Total Reflection (HATR) FT-IR spectroscopic analysis and optical parameters were also carried out for chromated samples. The study showed that the chromated samples had suitable absorbance and transmittance in the wavelength range (500-850 nm). Presence of chromium salt in the collagen samples increases the absorbance which improves the optical properties of the studied samples and leads to decrease the optical energy gap. The obtained optical energy gap gives an impression that the environmentally hazardous chrome shavings wastes can be utilized as a possible source of natural organic semiconductors with direct and indirect energy gap. This work opens the door to use some hazardous wastes in the manufacture of electronic devices such as IR-detectors, solar cells and also as solar cell windows. PMID:22070992

  3. Spectroscopic Study of Cyanoacetylene Cation: Slow Photo-Electron Spectroscopy and Ab-Initio Investigations

    NASA Astrophysics Data System (ADS)

    Mahjoub, Ahmed; Schwell, Martin; Benilan, Yves; Fray, Nicolas; Gazeau, Marie-Claire; Garcia, Gustavo A.; Gaie-Leverl, Francois; Champion, Norbert; Leach, Sydney

    2013-06-01

    Cyanoacetylene is one of the key minor constituents in the atmosphere of Titan. The ion HCCCN+ has been detected in this atmosphere and it is supposed to be formed by the reaction between C3H2+ and atomic nitrogen. We present here a spectroscopic investigation of the cyanoacetylene cation using photoexcitation of the neutral by vacuum-ultraviolet (VUV) synchrotron radiation coupled to a velocity map imaging electron/ion coincidence spectrometer. The cation spectroscopy is studied by the Slow Photoelectron Spectroscopy technique (SPES) (figure below) and the Total Ion Yield (TIY). The TIY has been calibrated to absolute units using the known propane absolute cross-section. Quantum chemical calculations are performed in order to interpret these spectra. These calculations deal with the equilibrium geometries, electronic-state patterns and evolutions, and harmonic and anharmonic wavenumbers. Through this study, we observe, in the auto-ionization region above the ionization energy, a number of Rydberg series of neutral cyanoacetylene. These Rydberg series converge to the first and second excited states of the cation. Acknowledgments. We are indebted to the general technical staff of Synchrotron Soleil for the running facility. C. Barrientos, P. Redondo and A. Largo J. Chem. Phys. A {104}(49), 11541-11548. 2000 L. Nahon, N. De Oliveria,J. F. Gil,B. Pilette,O. Marcouillé, B. La garde and F. Polack Journal of Synchrotron Radiation {19}(4), 508-520; 2012

  4. Confirming LBV Candidates Through Variability: A Photometric and Spectroscopic Monitoring Study

    NASA Astrophysics Data System (ADS)

    Stringfellow, Guy; Gvaramadze, Vasilii

    2012-02-01

    Luminous Blue Variable (LBV) stars represent an extremely rare class of very luminous, massive stars. About a dozen confirmed Galactic LBV stars are known, which precludes determining a solid evolutionary connection between LBV and other intermediate (e.g. Ofpe/WN9, WNL) phases in the life of very massive stars. Several catalogues of nebulae - rings and shells typical of LBVs - derived from the GLIMPSE and MIPSGAL surveys have recently been published. We conducted a near-IR spectral survey of a large subset of central stars residing within these nebulae and have identified nearly two dozen new candidate LBVs (cLBVs) based on spectral similarity alone; they remain cLBVs until 1-3 mag variability is demonstrated, securing their LBV nature. This marks a significant advancement in the study of massive stars, far outweighing the return from many studies searching for LBVs and WRs the past several decades. Using SMARTS 16 new cLBVs, 3 confirmed LBVs, and 2 previously known cLBVs will undergo photometric IR-monitoring, with 6 new cLBVs monitored spectroscopically (already being photometrically monitored elsewhere).

  5. Interactions of vinca alkaloid subunits with chiral amido[4]resorcinarenes: a dynamic, kinetic, and spectroscopic study.

    PubMed

    Botta, Bruno; Fraschetti, Caterina; Novara, Francesca R; Tafi, Andrea; Sacco, Fabiola; Mannina, Luisa; Sobolev, Anatoli P; Mattay, Jochen; Letzel, Matthias C; Speranza, Maurizio

    2009-05-01

    The stereoselectivity of the reaction between (R)-(-)-2-butylamine and the diastereomeric proton-bound complexes of (+)-catharanthine (C) or (-)-vindoline (V) with some chiral amido[4]resorcinarenes has been investigated in the gas phase by ESI-FT-ICR-MS. The reaction stereoselectivity (0.56 < k(homo)/k(hetero) < 16.9) is found to depend critically on the functional groups present in the chiral pendants of the hosts. Rationalisation of the kinetic results is based on careful computational and spectroscopic studies of the most stable conformations of (+)-catharanthine and its protonated form in the isolated state and in water, as well as in a representative host structure. The emerging picture points to the relevant diastereomeric proton-bound complexes as quasi-degenerate, thus suggesting that their stereoselectivity in the guest exchange reaction is mostly due to kinetic factors. The results of this study may represent a starting point for a deeper comprehension of the intrinsic factors that endow these molecules, and their dimeric forms, with their biochemical properties. PMID:19590774

  6. Measurement of moisture content in photovoltaic panel encapsulants using spectroscopic optical coherence tomography: a feasibility study

    NASA Astrophysics Data System (ADS)

    Rashtchi, Shabnam; Ruiz, Pablo D.; Wildman, Ricky; Ashcroft, Ian

    2012-10-01

    EVA, a copolymer of ethylene and vinyl acetate, is a common encapsulant material used in silicon-based PV modules. It contributes to the structural integrity of the modules, provides electrical insulation and also acts as an environmental barrier. However, water can diffuse through EVA into the modules, leading to swelling and chemical degradation, which can impact interfacial bonds, leading to delamination and allowing more ingress to occur that can eventually end up in accelerated corrosion and device failure. Fourier Transform infrared spectroscopy (FTIR) and gravimetric techniques have been used to quantify water concentration and the diffusion coefficient in free standing EVA films. However, these techniques cannot be applied to measure water content in PV modules deployed in the field, as the encapsulant is usually between a glass front sheet and a back sheet made of glass or multilayered films. In this paper we study the feasibility of combining FTIR and spectroscopic optical coherence tomography (SOCT) to measure water concentration of the EVA layer inside the modules. SOCT provides depth resolved spectral information and thus has the potential of measuring water absorption at different layers in the PV module. These depth-resolved measurements are necessary to inform predictive models developed to study the structural integrity, stability and durability of PV modules. The fundamental principle of the technique is explained, the optimum spectral ranges are identified and the feasibility of a SOCT system is discussed based on light source and detector characteristics. Other strategies are also considered.

  7. Human hemoglobin structural and functional alterations and heme degradation upon interaction with benzene: A spectroscopic study

    NASA Astrophysics Data System (ADS)

    Hosseinzadeh, Reza; Moosavi-Movahedi, Ali Akbar

    2016-03-01

    Here, the effect of benzene on hemoglobin structure, stability and heme prosthetic group integrity was studied by different methods. These included UV-vis absorption spectrophotometry, normal and synchronous fluorescence techniques, and differential scanning calorimetry (DSC). Our results indicated that benzene has high hemolytic potential even at low concentrations. The UV-vis spectroscopic results demonstrated that benzene altered both the globin chain and the heme prosthetic group of hemoglobin increasing met- and deoxy-Hb, while decreasing oxy-Hb. However, with increasing benzene the concentration of all species decreased due to heme destruction. The spectrophotometric results show that benzene has a high potential for penetrating the hydrophobic pocket of hemoglobin. These results were consistent with the molecular docking simulation results of benzene-hHb. Aggregation and thermal denaturation studies show that the increased benzene concentration induced hemoglobin aggregation with a decrease in stability, which is consistent with the DSC results. Conventional fluorescence spectroscopy revealed that the heme degradation species were produced in the presence of benzene. The results of constant wavelength synchronous fluorescence spectroscopy (CWSFS) indicated that at least five heme-degraded species were produced. Together, our results indicated that benzene has adverse effects on hemoglobin structure and function, and heme degradation.

  8. Studies on the inclusion behavior of 9-Aminoacridine into cyclodextrins: Spectroscopic and theoretical evidences

    NASA Astrophysics Data System (ADS)

    Manivannan, C.; Vijay Solomon, R.; Venuvanalingam, P.; Renganathan, R.

    2013-02-01

    9-Aminoacridine (9-AA) is an important attractive pharmaceutical drug employed as chemotheraptic agent for wound dressings. However, 9-AA possesses limited solubility and rapid metabolic decomposition renders this potential drug to limit its applications. Here we propose cyclodextrins (CDs) as a drug carrier to improve the bioavailability, solubility of 9-AA. The interaction between 9-AA and CDs (α-CD and β-CD) has been studied using UV-Vis absorption, steady state time resolved fluorescence, 1H NMR and FT-IR spectroscopy techniques. The spectroscopic measurements show that 9-AA does not form stable complex with α-CD and also confirmed by DFT calculations. On the other hand, 9-AA forms inclusion complex with β-CD in a 1:1 stoichiometry ratio. Our DFT results suggest that 9-AA stabilizes inside the CD environment through hydrogen bonding that has unambiguously confirmed by AIM analysis. Thus our studies provide a useful insights in the development of Aminoacridine based drugs & its delivery through a suitable carrier like CDs.

  9. LED phototherapy on midpalatal suture after rapid maxilla expansion: a Raman spectroscopic study

    NASA Astrophysics Data System (ADS)

    Rosa, Cristiane B.; Habib, Fernando Antonio L.; de Araújo, Telma M.; dos Santos, Jean N.; Cangussu, Maria Cristina T.; Barbosa, Artur Felipe S.; de Castro, Isabele Cardoso V.; Soares, Luiz Guilherme P.; Pinheiro, Antonio L. B.

    2015-03-01

    A quick bone formation after maxillary expansion would reduce treatment timeand the biomodulating effects of LED light could contribute for it. The aim of this study was to analyze the effect of LED phototherapy on the acceleration of bone formation at the midpalatal suture after maxilla expansion. Thirty rats divided into 6 groups were used on the study at 2 time points - 7 days: Control; Expansion; and Expansion + LED; and 14 days: Expansion; Expansion + LED in the first week; Expansion and LED in the first and second weeks. LED irradiation occurred at every 48 h during 2 weeks. Expansion was accomplished using a spatula and maintained with a triple helicoid of 0.020" stainless steel orthodontic wire. A LED light (λ850 ± 10nm, 150mW ± 10mW, spot of 0.5cm2, t=120 sec, SAEF of 18J/cm2) was applied in one point in the midpalatal suture immediately behind the upper incisors. Near infrared Raman spectroscopic analysis of the suture region was carried and data submitted to statistical analyzes (p≤0.05). Raman spectrum analysis demonstrated that irradiation increased hydroxyapatite in the midpalatal suture after expansion. The results of this indicate that LED irradiation; have a positive biomodulation contributing to the acceleration of bone formation in the midpalatal suture after expansion procedure.

  10. Time Domain Reflectometric and spectroscopic studies on toluene + butyronitrile solution

    NASA Astrophysics Data System (ADS)

    Karthick, N. K.; Arivazhagan, G.; Kumbharkhane, A. C.; Joshi, Y. S.; Kannan, P. P.

    2016-03-01

    The dielectric parameters of toluene + butyronitrile solution have been obtained by time domain reflectometry (TDR) technique in the frequency range from 10 MHz to 30 GHz at 298 K. Spectroscopic (FTIR and 13C NMR) studies have also been carried out on the solution and the results of the studies show that neat butyronitrile is self-associative through C-H⋯N contacts and weak intermolecular forces of C-H⋯N and C-H⋯π type are operative in the solution. The obtained dielectric parameters such as Kirkwood correlation factor g, relaxation time τ etc. have been analyzed in view of these weak intermolecular forces. The weak non-covalent interactions between heteromolecules appear to have no influence on the ideality of εm vs X2 curve of the solution. Heteromolecular entities with weak intermolecular forces experience larger hindrance leading to longer relaxation time τ.

  11. Potentiometric and spectroscopic study of the interaction of 3d transition metal ions with inositol hexakisphosphate

    NASA Astrophysics Data System (ADS)

    Veiga, Nicolás; Macho, Israel; Gómez, Kerman; González, Gabriel; Kremer, Carlos; Torres, Julia

    2015-10-01

    Among myo-inositol phosphates, the most abundant in nature is the myo-inositol hexakisphosphate, InsP6. Although it is known to be vital to cell functioning, the biochemical research into its metabolism needs chemical and structural analysis of all the protonation, complexation and precipitation processes that it undergoes in the biological media. In view of its high negative charge at physiological level, our group has been leading a thorough research into the InsP6 chemical and structural behavior in the presence of the alkali and alkaline earth metal ions essential for life. The aim of this article is to extend these studies, dealing with the chemical and structural features of the InsP6 interaction with biologically relevant 3d transition metal ions (Fe(II), Fe(III), Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)), in a non-interacting medium and under simulated physiological conditions. The metal-complex stability constants were determined by potentiometry, showing under ligand-excess conditions the formation of mononuclear species in different protonation states. Under metal ion excess, polymetallic species were detected for Fe(II), Fe(III), Zn(II) and Cu(II). Additionally, the 31P NMR and UV-vis spectroscopic studies provided interesting structural aspects of the strong metal ion-InsP6 interaction.

  12. Human hemoglobin structural and functional alterations and heme degradation upon interaction with benzene: A spectroscopic study.

    PubMed

    Hosseinzadeh, Reza; Moosavi-Movahedi, Ali Akbar

    2016-03-15

    Here, the effect of benzene on hemoglobin structure, stability and heme prosthetic group integrity was studied by different methods. These included UV-vis absorption spectrophotometry, normal and synchronous fluorescence techniques, and differential scanning calorimetry (DSC). Our results indicated that benzene has high hemolytic potential even at low concentrations. The UV-vis spectroscopic results demonstrated that benzene altered both the globin chain and the heme prosthetic group of hemoglobin increasing met- and deoxy-Hb, while decreasing oxy-Hb. However, with increasing benzene the concentration of all species decreased due to heme destruction. The spectrophotometric results show that benzene has a high potential for penetrating the hydrophobic pocket of hemoglobin. These results were consistent with the molecular docking simulation results of benzene-hHb. Aggregation and thermal denaturation studies show that the increased benzene concentration induced hemoglobin aggregation with a decrease in stability, which is consistent with the DSC results. Conventional fluorescence spectroscopy revealed that the heme degradation species were produced in the presence of benzene. The results of constant wavelength synchronous fluorescence spectroscopy (CWSFS) indicated that at least five heme-degraded species were produced. Together, our results indicated that benzene has adverse effects on hemoglobin structure and function, and heme degradation. PMID:26710175

  13. New insights into water splitting at mesoporous α-Fe2O3 films: a study by modulated transmittance and impedance spectroscopies.

    PubMed

    Cummings, Charles Y; Marken, Frank; Peter, Laurence M; Wijayantha, K G Upul; Tahir, Asif A

    2012-01-18

    Thin mesoporous films of α-Fe(2)O(3) have been prepared on conducting glass substrates using layer-by-layer self-assembly of ca. 4 nm hydrous oxide nanoparticles followed by calcining. The electrodes were used to study the oxygen evolution reaction (OER) in the dark and under illumination using in situ potential-modulated absorption spectroscopy (PMAS) and light-modulated absorption spectroscopy (LMAS) combined with impedance spectroscopy. Formation of surface-bound higher-valent iron species (or "surface trapped holes") was deduced from the PMAS spectra measured in the OER onset region. Similar LMAS spectra were obtained at more negative potentials in the onset region of photoelectrochemical OER, indicating involvement of the same intermediates. The impedance response of the mesoporous α-Fe(2)O(3) electrodes exhibits characteristic transmission line behavior that is attributed to slow hopping of holes, probably between surface iron species. Frequency-resolved PMAS and LMAS measurements revealed slow relaxation behavior that can be related to the impedance response and that indicates that the lifetime of the intermediates (or trapped holes) involved in the OER is remarkably long. PMID:22191733

  14. The effect of refluxing on the alkoxide-based sodium potassium niobate sol-gel system: Thermal and spectroscopic studies

    SciTech Connect

    Chowdhury, Anirban; Bould, Jonathan; Londesborough, Michael G.S.; Milne, Steven J.

    2011-02-15

    A study on the effects of prolonged heating under reflux conditions of up to 70 h on alkoxides of sodium, potassium and niobium dissolved in 2-methoxyethanol for the synthesis of sols of composition Na{sub 0.5}K{sub 0.5}NbO{sub 3} (NKN) has been carried out using combined thermogravimetric-Fourier transform infrared spectroscopic analyses. Extended refluxing increases the homogeneity of the Na{sub 0.5}K{sub 0.5}NbO{sub 3} (NKN) system. Spectroscopic analyses on the non-refluxed and 70 h refluxed NKN gels reveal the existence of inorganic hydrated carbonates and bicarbonates, which we propose arise from the hydration and carbonation of the samples on standing in air. The X-ray diffraction patterns of these two types of gels show orthorhombic NKN phase evolutions at higher temperatures. -- Graphical abstract: Total organic evolution plots over time for NKN dried gels obtained under different refluxing times show different thermochemical behaviours and these were investigated by thermal and spectroscopic analysis tools to find a correlation between the extent of -M-O-M- chain link formation and the amount of solvent vapour (methoxyethanol) evolution. Display Omitted Research highlights: > Prolonged refluxing of sol-gel NKN precursor solutions improves final properties of an NKN system. > An NKN process thermo-chemistry with thermal and spectroscopic analysis tools was explored. > An FTIR of NKN gels reveals tendency of NKN systems for rehydration and recarbonation on standing.

  15. Esophageal Impedance Monitoring: Clinical Pearls and Pitfalls.

    PubMed

    Ravi, Karthik; Katzka, David A

    2016-09-01

    The development of intraluminal esophageal impedance monitoring has improved our ability to detect and measure gastroesophageal reflux without dependence on acid content. This ability to detect previously unrecognized weak or nonacid reflux episodes has had important clinical implications in the diagnosis and management of gastroesophageal reflux disease (GERD). In addition, with the ability to assess bolus transit within the esophageal lumen, impedance monitoring has enhanced the recognition and characterization of esophageal motility disorders in patients with nonobstructive dysphagia. The assessment of the intraluminal movement of gas and liquid has also been proven to be of diagnostic value in conditions such as rumination syndrome and excessive belching. Further, alternative applications of impedance monitoring, such as the measurement of mucosal impedance, have provided novel insights into assessing esophageal mucosal integrity changes as a consequence of inflammatory change. Future applications for esophageal impedance monitoring also hold promise in esophageal conditions other than GERD. However, despite all of the clinical benefits afforded by esophageal impedance monitoring, important clinical and technical shortcomings limit its diagnostic value and must be considered when interpreting study results. Overinterpretation of studies or application of impedance monitoring in patients can have deleterious clinical implications. This review will highlight the clinical benefits and limitations of esophageal impedance monitoring and provide clinical pearls and pitfalls associated with this technology. PMID:27325223

  16. Line-Mixing Relaxation Matrix model for spectroscopic and radiative transfer studies

    NASA Astrophysics Data System (ADS)

    Mendaza, Teresa; Martin-Torres, Javier

    2016-04-01

    We present a generic model to compute the Relaxation Matrix easily adaptable to any molecule and type of spectroscopic lines or bands in non-reactive molecule collisions regimes. It also provides the dipole moment of every transition and level population of the selected molecule. The model is based on the Energy-Corrected Sudden (ECS) approximation/theory introduced by DePristo (1980), and on previous Relaxation Matrix studies for the interaction between molecular ro-vibrational levels (Ben-Rueven, 1966), atoms (Rosenkranz, 1975), linear molecules (Strow and Reuter, 1994; Niro, Boulet and Hartmann, 2004), and symmetric but not linear molecules (Tran et al., 2006). The model is open source, and it is user-friendly. To the point that the user only has to select the wished molecule and vibrational band to perform the calculations. It reads the needed spectroscopic data from the HIgh-resolution TRANsmission molecular absorption (HITRAN) (Rothman et al., 2013) and ExoMol (Tennyson and Yurchenko, 2012). In this work we present an example of the calculations with our model for the case of the 2ν3 band of methane (CH4), and a comparison with a previous work (Tran et al., 2010). The data produced by our model can be used to characterise the line-mixing effects on ro-vibrational lines of the infrared emitters of any atmosphere, to calculate accurate absorption spectra, that are needed in the interpretation of atmospheric spectra, radiative transfer modelling and General Circulation Models (GCM). References [1] A.E. DePristo, Collisional influence on vibration-rotation spectral line shapes: A scaling theoretical analysis and simplification, J. Chem. Phys. 73(5), 1980. [2] A. Ben-Reuven, Impact broadening of microwave spectra, Phys. Rev. 145(1), 7-22, 1966. [3] P.W. Rosenkranz, Shape of the 5 mm Oxygen Band in the Atmosphere, IEEE Transactions on Antennas and Propagation, vol. AP-23, no. 4, pp. 498-506, 1975. [4] Strow, L.L., D.D. Tobin, and S.E. Hannon, A compilation of

  17. Microparticle electrodes and single particle microbatteries: electrochemical and in situ microRaman spectroscopic studies.

    PubMed

    Jebaraj, Adriel Jebin Jacob; Scherson, Daniel A

    2013-05-21

    Studies of the intrinsic electrochemical, structural, and electronic propertiesof microparticles of energy storage materials can provide much needed insight into the factors that control various aspects of the performance of technical electrodes for battery applications. This Account summarizes efforts made in our laboratories toward the development and implementation of methods for the in situ electrical, optical, and spectroscopic characterization of microparticles of a variety of such materials, including Ni hydroxide, Zn, carbon, and lithiated Mn and Co oxides. In the case of Ni hydroxide, the much darker appearance of NiOOH compared to the virtually translucent character of virgin Ni(OH)2 allowed for the spatial and temporal evolution of charge flow within spherical microparticles of Ni(OH)2 to be monitored in real time during the first scan toward positive potentials using computer-controlled video imaging. In situ Raman scattering measurements involving single microparticles of Zn harvested from a commercial Zn|MnO2 battery revealed that passive films formed in strongly alkaline solutions by stepping the potential from 1.55 V to either 0.7 or 0.8 V vs SCE displayed a largely enhanced feature at ca. 565 cm(-1) ascribed to a longitudinal optical phonon mode of ZnO, an effect associated with the presence of interstitial Zn and oxygen deficiencies in the lattice. In addition, significant amounts of crystalline ZnO could be detected only for passive films formed at the same two potentials after the electrodes had been roughened by a single passivation-reduction step. Quantitative correlations were found in the case of LiMn2O4 and KS-44 graphite between the Raman spectral properties and the state of charge. In the case of KS-44, a chemometrics analysis of the spectroscopic data in the potential region in which the transition between dilute phase 1 and phase 4 of lithiated graphite is known to occur made it possible to determine independently the fraction of each

  18. An Imaging and Spectroscopic Study of Four Strong Mg II Absorbers Revealed by GRB 060418

    NASA Astrophysics Data System (ADS)

    Pollack, L. K.; Chen, H.-W.; Prochaska, J. X.; Bloom, J. S.

    2009-08-01

    We present results from an imaging and spectroscopic study of four strong Mg II absorbers of W(2796) gsim 1 Å revealed by the afterglow of GRB 060418 at z GRB = 1.491. These absorbers, at z = 0.603, 0.656, 1.107, and z GRB, exhibit large ion abundances that suggest neutral gas columns characteristic of damped Lyα systems. The imaging data include optical images obtained using Low-Resolution Imaging Spectrometer (LRIS) on the Keck I telescope and using Advanced Camera for Surveys on board Hubble Space Telescope, and near-infrared H-band images obtained using Persson's Auxiliary Nasmyth Infrared Camera on the Magellan Baade Telescope and K'-band images obtained using NIRC2 with laser guide star adaptive optics on the Keck II telescope. These images reveal six distinct objects at Δ θ lsim 3farcs5 of the afterglow's position, two of which exhibit well-resolved mature disk morphology, one shows red colors, and three are blue compact sources. Follow-up spectroscopic observations using LRIS confirm that one of the disk galaxies coincides with the Mg II absorber at z = 0.656. The observed broadband spectral energy distributions of the second disk galaxy and the red source indicate that they are associated with the absorbers at z = 0.603 and z = 1.107, respectively. These results show that strong Mg II absorbers identified in gamma-ray burst (GRB) afterglow spectra are associated with typical galaxies of luminosity ≈0.1 - 1 L * at impact parameter of ρ lsim 10 h -1 kpc. The close angular separation would preclude easy detections toward a bright quasar. Finally, we associate the remaining three blue compact sources with the GRB host galaxy, noting that they are likely star-forming knots located at projected distances of ρ = 2 - 12 h -1 kpc from the afterglow. At the afterglow's position, we derive a 2σ upper limit to the underlying star-formation rate intensity of 0.0074 M sun yr-1 kpc-2. Based in part on observations made with the NASA/ESA Hubble Space Telescope

  19. A M2FS Spectroscopic Study of Low-mass Young Stars in Orion OB1

    NASA Astrophysics Data System (ADS)

    Kaleida, Catherine C.; Briceno, Cesar; Calvet, Nuria; Mateo, Mario L.; Hernandez, Jesus

    2015-01-01

    Surveys of pre-main sequence stars in the ~4-10 Myr range provide a window into the decline of the accretion phase of stars and the formation of planets. Nearby star clusters and stellar associations allow for the study of these young stellar populations all the way down to the lowest mass members. One of the best examples of nearby 4-10 Myr old stellar populations is the Orion OB1 association. The CIDA Variability Survey of Orion OB1 (CVSO - Briceño et al. 2001) has used the variability properties of low-mass pre-main-sequence (PMS) stars to identify hundreds of K and M-type stellar members of the Orion OB1 association, a number of them displaying IR-excess emission and thought to be representative of more evolved disk-bearing young stars. Characterizing these young, low-mass objects using spectroscopy is integral to understanding the accretion phase in young stars. We present preliminary results of a spectroscopic survey of candidate and confirmed Orion OB1 low-mass members taken during November 2014 and February 2014 using the Michigan/Magellan Fiber Spectrograph (M2FS), a PI instrument on the Magellan Clay Telescope (PI: M. Matteo). Target fields located in the off-cloud regions of Orion were identified in the CVSO, and observed using the low and high-resolution modes of M2FS. Both low and high-resolution spectra are needed in order to confirm membership and derive masses, ages, kinematics and accretion properties. Initial analysis of these spectra reveal many new K and M-type members of the Orion OB1 association in these low extinction, off-cloud areas. These are the more evolved siblings of the youngest stars still embedded in the molecular clouds, like those in the Orion Nebula Cluster. With membership and spectroscopic indicators of accretion we are building the most comprehensive stellar census of this association, enabling us to derive a robust estimate of the fraction of young stars still accreting at a various ages, a key constraint for the end of

  20. AN IMAGING AND SPECTROSCOPIC STUDY OF FOUR STRONG Mg II ABSORBERS REVEALED BY GRB 060418

    SciTech Connect

    Pollack, L. K.; Prochaska, J. X.; Chen, H.-W.; Bloom, J. S.

    2009-08-20

    We present results from an imaging and spectroscopic study of four strong Mg II absorbers of W(2796) {approx}> 1 A revealed by the afterglow of GRB 060418 at z{sub GRB} = 1.491. These absorbers, at z = 0.603, 0.656, 1.107, and z {sub GRB}, exhibit large ion abundances that suggest neutral gas columns characteristic of damped Ly{alpha} systems. The imaging data include optical images obtained using Low-Resolution Imaging Spectrometer (LRIS) on the Keck I telescope and using Advanced Camera for Surveys on board Hubble Space Telescope, and near-infrared H-band images obtained using Persson's Auxiliary Nasmyth Infrared Camera on the Magellan Baade Telescope and K'-band images obtained using NIRC2 with laser guide star adaptive optics on the Keck II telescope. These images reveal six distinct objects at {delta} {theta} {approx}< 3.''5 of the afterglow's position, two of which exhibit well-resolved mature disk morphology, one shows red colors, and three are blue compact sources. Follow-up spectroscopic observations using LRIS confirm that one of the disk galaxies coincides with the Mg II absorber at z = 0.656. The observed broadband spectral energy distributions of the second disk galaxy and the red source indicate that they are associated with the absorbers at z = 0.603 and z = 1.107, respectively. These results show that strong Mg II absorbers identified in gamma-ray burst (GRB) afterglow spectra are associated with typical galaxies of luminosity {approx}0.1 - 1 L{sub *} at impact parameter of {rho} {approx}< 10 h {sup -1} kpc. The close angular separation would preclude easy detections toward a bright quasar. Finally, we associate the remaining three blue compact sources with the GRB host galaxy, noting that they are likely star-forming knots located at projected distances of {rho} = 2 - 12 h {sup -1} kpc from the afterglow. At the afterglow's position, we derive a 2{sigma} upper limit to the underlying star-formation rate intensity of 0.0074 M{sub sun} yr{sup -1} kpc

  1. Characterizing the structure of lipodisq nanoparticles for membrane protein spectroscopic studies.

    PubMed

    Zhang, Rongfu; Sahu, Indra D; Liu, Lishan; Osatuke, Anna; Comer, Raven G; Dabney-Smith, Carole; Lorigan, Gary A

    2015-01-01

    Membrane protein spectroscopic studies are challenging due to the difficulty introduced in preparing homogenous and functional hydrophobic proteins incorporated into a lipid bilayer system. Traditional membrane mimics such as micelles or liposomes have proved to be powerful in solubilizing membrane proteins for biophysical studies, however, several drawbacks have limited their applications. Recently, a nanosized complex termed lipodisq nanoparticles was utilized as an alternative membrane mimic to overcome these caveats by providing a homogeneous lipid bilayer environment. Despite all the benefits that lipodisq nanoparticles could provide to enhance the biophysical studies of membrane proteins, structural characterization in different lipid compositions that closely mimic the native membrane environment is still lacking. In this study, the formation of lipodisq nanoparticles using different weight ratios of POPC/POPG lipids to SMA polymers was characterized via solid-state nuclear magnetic resonance (SSNMR) spectroscopy and dynamic light scattering (DLS). A critical weight ratio of (1/1.25) for the complete solubilization of POPC/POPG vesicles has been observed and POPC/POPG vesicles turned clear instantaneously upon the addition of the SMA polymer. The size of lipodisq nanoparticles formed from POPC/POPG lipids at this weight ratio of (1/1.25) was found to be about 30 nm in radius. We also showed that upon the complete solubilization of POPC/POPG vesicles by SMA polymers, the average size of the lipodisq nanoparticles is weight ratio dependent, when more SMA polymers were introduced, smaller lipodisq nanoparticles were obtained. The results of this study will be helpful for a variety of biophysical experiments when specific size of lipid disc is required. Further, this study will provide a proper path for researchers working on membrane proteins to obtain pertinent structure and dynamic information in a physiologically relevant membrane mimetic environment. PMID

  2. Application of spectroscopic techniques for the analysis of kidney stones: a pilot study

    NASA Astrophysics Data System (ADS)

    Shameem, K. M., Muhammed; Chawla, Arun; Bankapur, Aseefhali; Unnikrishnan, V. K.; Santhosh, C.

    2016-03-01

    Identification and characterization of kidney stone remains one of the important analytical tasks in the medical field. Kidney stone is a common health complication throughout the world, which may cause severe pain, obstruction and infection of urinary tract, and can lead to complete renal damage. It commonly occurs in both sexes regardless of age. Kidney stones have different composition, although each stones have a major single characteristic component. A complete understanding of a sample properties and their function can only be feasible by utilizing elemental and molecular information simultaneously. Two laser based analytical techniques; Laser Induced Breakdown spectroscopy (LIBS) and Raman spectroscopy have been used to study different types of kidney stones from different patients. LIBS and Raman spectroscopy are highly complementary spectroscopic techniques, which provide elemental and molecular information of a sample. Q-switched Nd:YAG laser at 355 nm laser having energy 17mJ per pulse at 10 Hz repetition rate was used for getting LIBS spectra. Raman measurements were carried out using a home assembled micro-Raman spectrometer. Using the recorded Raman spectra of kidney stones, we were able to differentiate different kinds of kidney stones. LIBS spectra of the same stones are showing the evidence of C, Ca, H, and O and also suggest the presence of certain pigments.

  3. Spectroscopic Study of Terahertz Generation in Mid-Infrared Quantum Cascade Lasers

    NASA Astrophysics Data System (ADS)

    Jiang, Yifan; Vijayraghavan, Karun; Jung, Seungyong; Jiang, Aiting; Kim, Jae Hyun; Demmerle, Frederic; Boehm, Gerhard; Amann, Markus C.; Belkin, Mikhail A.

    2016-02-01

    Terahertz quantum cascade laser sources based on intra-cavity difference-frequency generation are currently the only room-temperature mass-producible diode-laser-like emitters of coherent 1-6 THz radiation. Device performance has improved dramatically over the past few years to reach milliwatt-level power output and broad tuning from 1.2 to 5.9 THz, all at room-temperature. Terahertz output in these sources originates from intersubband optical nonlinearity in the laser active region. Here we report the first comprehensive spectroscopic study of the optical nonlinearity and investigate its dependence on the mid-infrared pump frequencies. Our work shows that the terahertz generation efficiency can vary by a factor of 2 or greater depending on the spectral position of the mid-infrared pumps for a fixed THz difference-frequency. We have also measured for the first time the linewidth for transitions between the lower quantum cascade laser states, which is critical for determining terahertz nonlinearity and predicting optical loss in quantum cascade laser waveguides.

  4. Photometric and spectroscopic study of low mass embedded star clusters in reflection nebulae

    NASA Astrophysics Data System (ADS)

    Soares, J. B.; Bica, E.; Ahumada, A. V.; Clariá, J. J.

    2005-02-01

    An analysis of the candidate embedded stellar systems in the reflection nebulae vdBH-RN 26, vdBH-RN} 38, vdBH-RN} 53a, GGD 20, ESO 95-RN 18 and NGC 6595 is presented. Optical spectroscopic data from CASLEO (Argentina) in conjunction with near infrared photometry from the 2MASS Point Source Catalogue were employed. The analysis is based on source surface density, colour-colour and colour-magnitude diagrams together with theoretical pre-main sequence isochrones. We take into account the field population affecting the analysis by carrying out a statistical subtraction. The fundamental parameters for the stellar systems were derived. The resulting ages are in the range 1-4 Myr and the objects are dominated by pre-main sequence stars. The observed masses locked in the clusters are less than 25 M⊙. The studied systems have no stars of spectral types earlier than B, indicating that star clusters do not necessarily evolve through an HII region phase. The relatively small locked mass combined with the fact that they are not numerous in catalogues suggests that these low mass clusters are not important donors of stars to the field populations. Based on observations made at Complejo Astronómico El Leoncito, which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba and San Juan, Argentina.

  5. Synthesis, spectroscopic characterization and electrochemical studies of Girard's T chromone complexes

    NASA Astrophysics Data System (ADS)

    Al-Saeedi, Sameerah I.; Alaghaz, Abdel-Nasser M. A.; Ammar, Reda A.

    2016-05-01

    Complexes of cobalt(II), nickel(II), copper(II) and zinc(II) of general composition [M(L)2] have been. The elemental analyses, molar conductance, spectral, magnetic moment and thermal measurements studies of the compounds led to the conclusion that the ligand acts as a tridentate manner (OON). The molar conductance of the metal complexes in fresh solution of DMSO lies in the range of 8.10-10.18 Ω-1 cm2 mol-1 indicating their non-electrolytic behavior. On the basis of analytical and spectroscopic techniques, octahedral geometry of the complexes was proposed. The ligand field parameters were calculated for Co(II), Ni(II) and Cu(II) complexes and their values were found in the range reported for a octahedral structure. The data show that the complexes have composition of ML2 type. The activation of thermodynamic parameters are calculated using different equations. The octahedral geometry of the complexes is confirmed using DFT method from DMOL3 calculations and ligand field parameters. The cyclic voltammograms of the Cu(II)/Co(II)/Ni(II) complexes investigated in DMSO solution exhibit metal centered electroactivity in the potential range -1.5 to +1.5 V. The electrochemical data obtained for Cu(II) complexes explains the change of structural arrangement of the ligand around Cu(II) ions.

  6. Structural, spectroscopic and DFT study of 4-methoxybenzohydrazide Schiff bases. A new series of polyfunctional ligands

    NASA Astrophysics Data System (ADS)

    Ferraresi-Curotto, Verónica; Echeverría, Gustavo A.; Piro, Oscar E.; Pis-Diez, Reinaldo; González-Baró, Ana C.

    2015-02-01

    Five Schiff bases obtained from condensation of 4-methoxybenzohydrazide with related aldehydes, namely o-vanillin, vanillin, 5-bromovanillin, 5-chlorosalicylaldehyde and 5-bromosalicylaldehyde were prepared. A detailed structural and spectroscopic study is reported. The crystal structures of four members of the family were determined and compared with one another. The hydrazones obtained from 5-chlorosalicylaldehyde and 5-bromosalicylaldehyde resulted to be isomorphic to each other. The solid-state structures are stabilized by intra-molecular Osbnd H⋯N interactions in salicylaldehyde derivatives between the Osbnd H moiety from the aldehyde and the hydrazone nitrogen atom. All crystals are further stabilized by inter-molecular H-bonds mediated by the crystallization water molecule. A comparative analysis between experimental and theoretical results is presented. The conformational space was searched and geometries were optimized both in gas phase and including solvent effects. The structure is predicted for the compound for which the crystal structure was not determined. Infrared and electronic spectra were measured and assigned with the help of data obtained from computational methods based on the Density Functional Theory.

  7. A combined spectroscopic and theoretical study of propofol.(H2O)3

    NASA Astrophysics Data System (ADS)

    León, Iker; Cocinero, Emilio J.; Millán, Judith; Rijs, Anouk M.; Usabiaga, Imanol; Lesarri, Alberto; Castaño, Fernando; Fernández, José A.

    2012-08-01

    Propofol (2,6-di-isopropylphenol) is probably the most widely used general anesthetic. Previous studies focused on its complexes containing 1 and 2 water molecules. In this work, propofol clusters containing three water molecules were formed using supersonic expansions and probed by means of a number of mass-resolved laser spectroscopic techniques. The 2-color REMPI spectrum of propofol.(H2O)3 contains contributions from at least two conformational isomers, as demonstrated by UV/UV hole burning. Using the infrared IR/UV double resonance technique, the IR spectrum of each isomer was obtained both in ground and first excited electronic states and interpreted in the light of density functional theory (DFT) calculations at M06-2X/6-311++G(d,p) and B3LYP/6-311++G(d,p) levels. The spectral analysis reveals that in both isomers the water molecules are forming cyclic hydrogen bond networks around propofol's OH moiety. Furthermore, some evidences point to the existence of isomerization processes, due to a complicated conformational landscape and the existence of multiple paths with low energy barriers connecting the different conformers. Such processes are discussed with the aid of DFT calculations.

  8. Spectroscopic studies on the interaction of fluorine containing triazole with bovine serum albumin.

    PubMed

    Liu, Yang; Mei, Ping; Zhang, Ye-Zhong; Sun, Xiao-Hong; Liu, Yi

    2010-12-01

    The binding of one fluorine including triazole (C(10)H(9)FN(4)S, FTZ) to bovine serum albumin (BSA) was studied by spectroscopic techniques including fluorescence spectroscopy, UV-Vis absorption, and circular dichroism (CD) spectroscopy under simulative physiological conditions. Fluorescence data revealed that the fluorescence quenching of BSA by FTZ was the result of forming a complex of BSA-FTZ, and the binding constants (K (a)) at three different temperatures (298, 304, and 310 K) were 1.516 × 10(4), 1.627 × 10(4), and 1.711 × 10(4) mol L(-1), respectively, according to the modified Stern-Volmer equation. The thermodynamic parameters ΔH and ΔS were estimated to be 7.752 kJ mol(-1) and 125.217 J mol(-1) K(-1), respectively, indicating that hydrophobic interaction played a major role in stabilizing the BSA-FTZ complex. It was observed that site I was the main binding site for FTZ to BSA from the competitive experiments. The distance r between donor (BSA) and acceptor (FTZ) was calculated to be 7.42 nm based on the Förster theory of non-radioactive energy transfer. Furthermore, the analysis of fluorescence data and CD data revealed that the conformation of BSA changed upon the interaction with FTZ. PMID:20195922

  9. A theoretical benchmark study of the spectroscopic constants of the very heavy rare gas dimers.

    PubMed

    Shee, Avijit; Knecht, Stefan; Saue, Trond

    2015-04-28

    Spectroscopic constants for the homonuclear dimers of the very heavy rare gases radon (Rn) and eka-radon (Uuo) are reported. A computational protocol using the eXact 2-Component molecular-mean field Hamiltonian has been established based on extensive calculations of the xenon dimer. We find that reliable results require CCSD(T) calculations at the extrapolated basis set limit. In this limit counterpoise corrected results are closer to experimentally derived values than uncorrected ones. Furthermore, in an attempt to reduce the computational cost while retaining very high accuracy, we studied the performance of range-separated density functional theory. Although we observe a somewhat more favorable basis set convergence and reduced importance of connected triples by range-separated methods compared to pure wave function theory, in practice we have to employ the same computational protocol for obtaining converged results. At the Dirac-Coulomb level we find an almost fourfold increase of binding energy when going from the radon to the eka-radon dimer, but the inclusion of spin-other orbit interaction reduces the dissociation energy of the heaviest dimer by about 40%. PMID:25825068

  10. Atomically resolved spectroscopic study of Sr2IrO4: Experiment and theory

    PubMed Central

    Li, Qing; Cao, Guixin; Okamoto, Satoshi; Yi, Jieyu; Lin, Wenzhi; Sales, Brian C.; Yan, Jiaqiang; Arita, Ryotaro; Kuneš, Jan; Kozhevnikov, Anton V.; Eguiluz, Adolfo G.; Imada, Masatoshi; Gai, Zheng; Pan, Minghu; Mandrus, David G.

    2013-01-01

    Particularly in Sr2IrO4, the interplay between spin-orbit coupling, bandwidth and on-site Coulomb repulsion stabilizes a Jeff = 1/2 spin-orbital entangled insulating state at low temperatures. Whether this insulating phase is Mott- or Slater-type, has been under intense debate. We address this issue via spatially resolved imaging and spectroscopic studies of the Sr2IrO4 surface using scanning tunneling microscopy/spectroscopy (STM/S). STS results clearly illustrate the opening of an insulating gap (150 ~ 250 meV) below the Néel temperature (TN), in qualitative agreement with our density-functional theory (DFT) calculations. More importantly, the temperature dependence of the gap is qualitatively consistent with our DFT + dynamical mean field theory (DMFT) results, both showing a continuous transition from a gapped insulating ground state to a non-gap phase as temperatures approach TN. These results indicate a significant Slater character of gap formation, thus suggesting that Sr2IrO4 is a uniquely correlated system, where Slater and Mott-Hubbard-type behaviors coexist. PMID:24166292

  11. Spectroscopic studies on the interaction of cinnamic acid and its hydroxyl derivatives with human serum albumin

    NASA Astrophysics Data System (ADS)

    Min, Jiang; Meng-Xia, Xie; Dong, Zheng; Yuan, Liu; Xiao-Yu, Li; Xing, Chen

    2004-04-01

    Cinnamic acid and its derivatives possess various biological effects in remedy of many diseases. Interaction of cinnamic acid and its hydroxyl derivatives, p-coumaric acid and caffeic acid, with human serum albumin (HSA), and concomitant changes in its conformation were studied using fluorescence and Fourier transform infrared spectroscopic methods. Fluorescence data revealed the presence of one binding site on HSA for cinnamic acid and its hydroxyl derivatives, and their binding constants ( KA) are caffeic acid> p-coumaric acid> cinnamic acid when Cdrug/ CHSA ranging from 1 to 10. The changes of the secondary structure of HSA after interacting with the three drugs are estimated, respectively by combining the curve-fitting results of amid I and amid III bands. The α-helix structure has a decrease of ≈9, 5 and 3% after HSA interacted with caffeic acid, p-coumaric acid and cinnamic acid, respectively. It was found that the hydroxyls substituted on aromatic ring of the drugs play an important role in the changes of protein's secondary structure. Combining the result of fluorescence quenching and the changes of secondary structure of HSA after interaction with the three drugs, the drug-HSA interaction mode was discussed.

  12. Spectroscopic Study of Terahertz Generation in Mid-Infrared Quantum Cascade Lasers.

    PubMed

    Jiang, Yifan; Vijayraghavan, Karun; Jung, Seungyong; Jiang, Aiting; Kim, Jae Hyun; Demmerle, Frederic; Boehm, Gerhard; Amann, Markus C; Belkin, Mikhail A

    2016-01-01

    Terahertz quantum cascade laser sources based on intra-cavity difference-frequency generation are currently the only room-temperature mass-producible diode-laser-like emitters of coherent 1-6 THz radiation. Device performance has improved dramatically over the past few years to reach milliwatt-level power output and broad tuning from 1.2 to 5.9 THz, all at room-temperature. Terahertz output in these sources originates from intersubband optical nonlinearity in the laser active region. Here we report the first comprehensive spectroscopic study of the optical nonlinearity and investigate its dependence on the mid-infrared pump frequencies. Our work shows that the terahertz generation efficiency can vary by a factor of 2 or greater depending on the spectral position of the mid-infrared pumps for a fixed THz difference-frequency. We have also measured for the first time the linewidth for transitions between the lower quantum cascade laser states, which is critical for determining terahertz nonlinearity and predicting optical loss in quantum cascade laser waveguides. PMID:26879901

  13. Spectroscopic studies of the interaction of bichromophoric cyanine dyes with DNA. Effect of ionic strength.

    PubMed

    Schaberle, Fábio A; Kuz'min, Vladimir A; Borissevitch, Iouri E

    2003-05-01

    Spectroscopic characteristics of a cyanine dye with two chromophores (biscyanine dye, BCD) in aqueous solutions and effects of NaCl and DNA upon these characteristics have been studied by optical absorption, circular dichroism (CD) and fluorescence spectroscopies. In homogeneous solutions, BCD is characterized by intense optical absorption (epsilon =1.33 x 10(5) M(-1) x cm(-1)) and weak fluorescence (phi(fl)=0.018) in the wavelength region greater than 600 nm. The dye forms H-aggregates at low concentrations (10(-6) M). NaCl stimulates the formation of both H- and J-aggregates of the dye at much lower dye concentrations, while DNA in low concentrations (<10(-6) M) stimulated the formation of just J-aggregates on the surface of the DNA molecule. Higher DNA concentrations induce the dye to disaggregate, and there exists an equilibrium between three dye forms: free monomers, J-aggregates and bound monomers, the maximum content of J-aggregates was observed at [DNA]/[BCD]=0.6+/-0.2 and total disaggregation at [DNA]/[BCD]=190+/-20. J-aggregates are characterized by phi(fl)=0.05 and bound monomers by phi(fl)=0.44. In the presence of NaCl, total disaggregation was observed at [DNA]/[BCD]=570+/-10 due to competition between Na(+) and the dye molecules for DNA electronegative binding sites. PMID:12726994

  14. Spectroscopic and MD simulation studies on unfolding processes of mitochondrial carbonic anhydrase VA induced by urea.

    PubMed

    Idrees, Danish; Prakash, Amresh; Haque, Md Anzarul; Islam, Asimul; Ahmad, Faizan; Hassan, Md Imtaiyaz

    2016-09-01

    Carbonic anhydrase VA (CAVA) is primarily expressed in the mitochondria and involved in numerous physiological processes including lipogenesis, insulin secretion from pancreatic cells, ureagenesis, gluconeogenesis and neuronal transmission. To understand the biophysical properties of CAVA, we carried out a reversible urea-induced isothermal denaturation at pH 7.0 and 25°C. Spectroscopic probes, [θ]222 (mean residue ellipticity at 222 nm), F344 (Trp-fluorescence emission intensity at 344 nm) and Δε280 (difference absorption at 280 nm) were used to monitor the effect of urea on the structure and stability of CAVA. The urea-induced reversible denaturation curves were used to estimate [Formula: see text], Gibbs free energy in the absence of urea; Cm, the mid-point of the denaturation curve, i.e. molar urea concentration ([urea]) at which ΔGD = 0; and m, the slope (=∂ΔGD/∂[urea]). Coincidence of normalized transition curves of all optical properties suggests that unfolding/refolding of CAVA is a two-state process. We further performed 40 ns molecular dynamics simulation of CAVA to see the dynamics at different urea concentrations. An excellent agreement was observed between in silico and in vitro studies. PMID:26421381

  15. Synthesis and spectroscopic studies of some chromium and molybdenum derivatives of bis-(acetylacetone)ethylenediimine ligand

    NASA Astrophysics Data System (ADS)

    Ramadan, Ramadan M.; Abdel-Rahman, Laila H.; Ismael, Mohamed; Youssef, Teraze A.; Ali, Saadia A.

    2013-10-01

    Interaction of [Cr(CO)6] with bis-(acetylacetone)ethylenediimine Schiff base, H2acacen, under reduced pressure resulted in the formation of [Cr(CO)3(H2acacen)] derivative. The Schiff base acted as a tridentate and coordinated the metal through the nitrogen of the azomethine groups and one hydroxyl group. Reaction of [Mo(CO)6] with H2acacen under sunlight irradiation in presence of air gave the oxo derivative [Mo2O6(H2acacen)2]. The ligand acted as a bidentate and coordinated the metal through the two imine groups. In presence of 2,2'-bipyridine (bpy), the reaction of [Mo(CO)6] with H2acacen gave [Mo2O6(bpy)(H2acacec)]. The structures of the reported complexes were proposed on the basis of spectroscopic studies. The proposed structures were also verified by theoretical calculations based on accurate DFT approximations. Moreover, the relative reactivity was estimated using chemical descriptors analysis.

  16. Spectroscopic studies and biological activity of some transition metal complexes of unusual Schiff base

    NASA Astrophysics Data System (ADS)

    Abu Al-Nasr, Ahmad K.; Ramadan, Ramadan M.

    2013-03-01

    Unusual Schiff base ligand, 4-ethanimidoyl-6-[(1E)-N-(2-hydroxy-4-methylphenyl)ethanimidoyl]benzene-1,3-diol, L, was synthesized via catalytic process involving the interaction of some metal ions with a macrocyclic Schiff base (MSB). The transition metal derivatives [ML(H2O)4](NO3)3, M = Cr(III) and Fe(III), [NiL(H2O)4](NO3)2, [ML(H2O)2](NO3)2, M = Zn(II) and Cd(II), [Cl2Pd(μ-Cl)2PdL], [PtL(Cl)2] and [PtL(Cl)4] were also synthesized from the corresponding metal species with L. The Schiff bases and complexes were characterized by elemental analysis, mass spectrometry, IR and 1H NMR spectroscopy. The crystal structure of L was determined by X-ray analysis. The spectroscopic studies revealed a variety of structure arrangements for the complexes. The biological activities of L and metal complexes against the Escherchia coli as Gram-negative bacteria and Staphylococcus aureus as Gram-positive bacteria, and the two fungus Aspergillus flavus and Candida albicans were screened. The cytotoxicity of [PtL(Cl)2] complex, a cis-platin analogous, was checked as an antitumor agent on two breast cancer cell lines (MCF7 and T47D) and human liver carcinoma cell line (HepG2).

  17. {sup 1}H NMR spectroscopic studies establish that heparanase is a retaining glycosidase

    SciTech Connect

    Wilson, Jennifer C.; Laloo, Andrew Elohim; Singh, Sanjesh; Ferro, Vito

    2014-01-03

    Highlights: •{sup 1}H and {sup 13}C NMR chemical shifts of fondaparinux were fully assigned by 1D and 2D NMR techniques. •Hydrolysis of fondaparinux by heparanase was monitored by {sup 1}H NMR spectroscopy. •Heparanase is established to be a retaining glycosidase. -- Abstract: Heparanase is an endo-β-glucuronidase that cleaves heparan sulfate side chains of proteoglycans in basement membranes and the extracellular matrix (ECM). Heparanase is implicated in several diverse pathological processes associated with ECM degradation such as metastasis, inflammation and angiogenesis and is thus an important target for anti-cancer and anti-inflammatory drug discovery. Heparanase has been classed as belonging to the clan A glycoside hydrolase family 79 based on sequence analysis, secondary structure predictions and mutagenic analysis, and thus it has been inferred that it is a retaining glycosidase. However, there has been no direct experimental evidence to support this conclusion. Herein we describe {sup 1}H NMR spectroscopic studies of the hydrolysis of the pentasaccharide substrate fondaparinux by heparanase, and provide conclusive evidence that heparanase hydrolyses its substrate with retention of configuration and is thus established as a retaining glycosidase. Knowledge of the mechanism of hydrolysis may have implications for future design of inhibitors for this important drug target.

  18. WIYN open cluster study. LX. Spectroscopic binary orbits in NGC 6819

    SciTech Connect

    Milliman, Katelyn E.; Mathieu, Robert D.; Gosnell, Natalie M.; Geller, Aaron M.; Meibom, Søren; Platais, Imants

    2014-08-01

    We present the current state of the WOCS radial-velocity (RV) survey for the rich open cluster NGC 6819 (2.5 Gyr) including 93 spectroscopic binary orbits with periods ranging from 1.5 to 8000 days. These results are the product of our ongoing RV survey of NGC 6819 using the Hydra Multi-Object Spectrograph on the WIYN 3.5 m telescope. We also include a detailed analysis of multiple prior sets of optical photometry for NGC 6819. Within a 1° field of view, our stellar sample includes the giant branch, the red clump, and blue straggler candidates, and extends to almost 2 mag below the main sequence (MS) turnoff. For each star observed in our survey we present all RV measurements, the average RV, and velocity variability information. Additionally, we discuss notable binaries from our sample, including eclipsing binaries (WOCS 23009, WOCS 24009, and WOCS 40007), stars noted in Kepler asteroseismology studies (WOCS 4008, WOCS 7009, and WOCS 8007), and potential descendants of past blue stragglers (WOCS 1006 and WOCS 6002). We find the incompleteness-corrected binary fraction for all MS binaries with periods less than 10{sup 4} days to be 22% ± 3% and a tidal circularization period of 6.2{sub −1.1}{sup +1.1} days for NGC 6819.

  19. Spectroscopic study of Be-shell stars: 4 Her and 88 Her

    NASA Astrophysics Data System (ADS)

    Bhat, Shruthi S.; Paul, K. T.; Subramaniam, Annapurni; Mathew, Blesson

    2016-05-01

    We present an optical spectroscopic study based on 41 spectra of 4 Her and 32 spectra of 88 Her, obtained over a period of 6 months. We estimate the rotational velocity of these stars from HeI lines in the blue spectral region (4000–4500 Å). We find that these stars are likely to be rotating at a fractional critical rotation of ∼0.80. We measure the average I p/I c ratio to quantify the strength of the Hα line and obtain 1.63 for 4 Her and 2.06 for 88 Her. The radius of the Hα emission region is estimated to be Rd/R* ∼5.0, assuming a Keplerian disk. These stars are thus found to be fast rotators with a relatively small Hα emission region. We detect V/R variation of the Hα spectral line during the observed period. We re-estimate the periods for both stars and obtain a period of ∼46 d and its harmonic of 23.095 d for 4 Her, and a period of ∼86 d for 88 Her. As these two cases are shell stars with binaries and have low Hα EW with the emission region closer to the central star, the V/R variation and a change in period may be an effect of the binary on the circumstellar disk.

  20. Spectroscopic investigations, molecular interactions, and molecular docking studies on the potential inhibitor "thiophene-2-carboxylicacid"

    NASA Astrophysics Data System (ADS)

    Karthick, T.; Balachandran, V.; Perumal, S.

    2015-04-01

    Thiophene derivatives have been focused in the past decades due to their remarkable biological and pharmacological activities. In connection with that the conformational stability, spectroscopic characterization, molecular (inter- and intra-) interactions, and molecular docking studies on thiophene-2-carboxylicacid have been performed in this work by experimental FT-IR and theoretical quantum chemical computations. Experimentally recorded FT-IR spectrum in the region 4000-400 cm-1 has been compared with the scaled theoretical spectrum and the spectral peaks have been assigned on the basis of potential energy distribution results obtained from MOLVIB program package. The conformational stability of monomer and dimer conformers has been examined. The presence of inter- and intramolecular interactions in the monomer and dimer conformers have been explained by natural bond orbital analysis. The UV-Vis spectra of the sample in different solvents have been simulated and solvent effects were predicted by polarisable continuum model with TD-DFT/B3LYP/6-31+G(d,p) method. To test the biological activity of the sample, molecular docking (ligand-protein) simulations have been performed using SWISSDOCK web server. The full fitness (FF) score and binding affinity values revealed that thiophene-2-carboxylicacid can act as potential inhibitor against inflammation.

  1. Photometric and spectroscopic study of the intermediate-age open cluster NGC 2355

    NASA Astrophysics Data System (ADS)

    Donati, P.; Bragaglia, A.; Carretta, E.; D'Orazi, V.; Tosi, M.; Cusano, F.; Carini, R.

    2015-11-01

    In this paper we analyse the evolutionary status and properties of the old open cluster NGC 2355, located in the Galactic anticentre direction, as a part of the long-term programme Bologna Open Clusters Chemical Evolution. NGC 2355 was observed with the Large Binocular Camera at the Large Binocular Telescope using the Bessel B, V, and Ic filters. The cluster parameters have been obtained using the synthetic colour-magnitude diagram method, as done in other papers of this series. Additional spectroscopic observations with the Fibre-fed Echelle Spectrograph at the Nordic Optical Telescope of three giant stars were used to determine the chemical properties of the cluster. Our analysis shows that NGC 2355 has metallicity slightly less than solar, with [Fe/H]= -0.06 dex, age between 0.8 and 1 Gyr, reddening E(B - V) in the range 0.14-0.19 mag, and distance modulus (m - M)0 of about 11 mag. We also investigate the abundances of O, Na, Al, α, iron-peak, and neutron capture elements, showing that NGC 2355 falls within the abundance distribution of similar clusters (same age and metallicity). The Galactocentric distance of NGC 2355 places it at the border between two regimes of metallicity distribution; this makes it an important cluster for the study of the chemical properties and evolution of the disc.

  2. Pb(II) binding to humic substances: an equilibrium and spectroscopic study.

    PubMed

    Orsetti, Silvia; Marco-Brown, Jose L; Andrade, Estela M; Molina, Fernando V

    2013-08-01

    The binding of Pb(II) to humic acids is studied through an approach combining equilibrium and spectroscopic measurements. The methods employed are potentiometric and fluorometric titrations, fluorescence excitation-emission matrices (EEM) and IR spectroscopy. Potentiometric titration curves are analyzed using the NICA equations and an electrostatic model treating the humic particles as an elastic polyelectrolyte network. EEMs are analyzed using parallel factor analysis, decomposing the signal in its independent components and finding their dependence on Pb(II) activity. Potentiometric results are consistent with bimodal affinity distributions for Pb(II) binding, whereas fluorometric titrations are explained by monomodal distributions. EEM analysis is consistent with three independent components in the humic fluorescence response, which are assigned to moieties with different degree of aromaticity. All three components show a similar quenching behavior upon Pb(II) binding, saturating at relatively low Pb(II) concentrations. This is attributed to metal ion induced aggregation of humic molecules, resulting in the interaction between the aromatic groups responsible for fluorescence; this is also consistent with IR spectroscopy results. The observed behavior is interpreted considering that initial metal binding (observed as strongly binding sites), correspond to bi- or multidentate complexation to carboxylate groups, including binding between groups of different humic molecules, promoting aggregation; further metal ions (observed as weakly binding sites) bind to single ligand groups. PMID:23805795

  3. Development of Polarized Solid Targets for Spectroscopic Studies with Radioactive Ion Beams.

    NASA Astrophysics Data System (ADS)

    Urrego-Blanco, J. P.; Galindo-Uribarri, A.; van den Brandt, B.

    2005-04-01

    Exciting new findings with radioactive ion beams (RIBs) in nuclear spectroscopy have resulted in a growing interest in this field. In order to fully exploit the potential of RIBs it is necessary to develop appropriate experimental tools. We are investigating the possibility of introducing polarization observables in spectroscopic studies with RIBs, at energies around the Coulomb barrier, through polystyrene targets of polarized protons and deuterons in the thickness range between 20 and 100μm. The operation of such target systems requires a cooling scheme where the target is situated in the isolation vacuum of a cryostat in open connection to the vacuum of the beamline. This can be achieved by using two parallel polarized foils mounted on a copper tube, serving also as the NMR coil (for sampling the polarization), to form together a closed volume. Cooling of the foils is then achieved by a liquid helium bath (^4He or ^3He) via the copper tube, and subsequently via a superfluid ^4He film that can be added through the hollow NMR coil. The first tests of this proposed geometry are discussed and a status of the project is delivered.

  4. Raman spectroscopic study of gadolinium (III) in sodium-aluminoborosilicate glasses

    SciTech Connect

    Li, Hong; Su, Yali ); Li, Liyu ); Strachan, Denis M. )

    2000-11-01

    Raman spectroscopic study was performed on a series of sodium-aluminoborosilicate glasses with Gd2O3 from 0 up to its solubility (13.58 mol% or 47 mass%). Experimentally measured spectra were fitted using a Gaussian function for each individual band without any restrictions of the band position, width, and intensity. The evolution of the bands derived from the curve fitting was discussed within a contest of rare earth element partitioning, as its dissolution mechanism, in the borosilicate glasses. The evolution of the Raman bands was shown to well correlate with Gd cations partitioning in the borate-rich environment at low Gd2O3 concentration, Gd2O3/[1/3B2O3] < 1, and in the silicate-rich environment at high Gd2O3 concentration, Gd2O3/[1/3B2O3] > 1. Raman bands near 1420 and 710 cm-1 suggest the presence of a local Gd-metaborate environment, which appeared to remain over an entire Gd2O3 concentration region. The bands near 300 and 910 cm-1 indicates formation of Gd-O-Gd clusters in the silicate-rich environment at high Gd2O3 concentrations.

  5. Infrared spectroscopic studies of galvanic effect influence on surface modification of sulfide minerals by surfactant adsorption.

    PubMed

    Mielczarski, Ela; Mielczarski, Jerzy A

    2005-08-15

    The influence of interaction between mineral components in natural mixtures on the adsorption of organic and inorganic species on the mineral surfaces is recognized. However, the surface phenomena have been meagerly investigated. In this study the formation of different surface species of surfactant (amyl xanthate, C5H11OC(S)S-) adsorbed on FeS2, PbS, and CuFeS2 has been spectroscopically investigated in single-mineral and complex systems. The type and amount of adsorbed species were determined directly on each mineral surface by infrared external reflection spectroscopy. Galvanic interaction between grains of different minerals could have tremendous consequence on the adsorption of surfactants on each mineral component and their future reactivity. The detected changes are dramatic, from no adsorption to the formation of several layers of hydrophobic or hydrophilic surface products depending on which minerals are in contact. It has been documented that even very short contact time between different mineral grains by collision is sufficient to produce dramatic modification of the surface composition and structure. The results obtained indicate clearly that the observations and conclusions aboutthe surfactant adsorption made in a single mineral system cannot be simply extrapolated to describe the real situation in natural multicomponent mineral systems. The obtained information on sulfide mineral interaction in complex systems is indispensable to understand processes taking place in nature at mineral-water interfaces (dissolution of heavy metals). An additional benefit is the improved ability to design efficient separation processes of these minerals. PMID:16173571

  6. Spectroscopic Study of Terahertz Generation in Mid-Infrared Quantum Cascade Lasers

    PubMed Central

    Jiang, Yifan; Vijayraghavan, Karun; Jung, Seungyong; Jiang, Aiting; Kim, Jae Hyun; Demmerle, Frederic; Boehm, Gerhard; Amann, Markus C.; Belkin, Mikhail A.

    2016-01-01

    Terahertz quantum cascade laser sources based on intra-cavity difference-frequency generation are currently the only room-temperature mass-producible diode-laser-like emitters of coherent 1–6 THz radiation. Device performance has improved dramatically over the past few years to reach milliwatt-level power output and broad tuning from 1.2 to 5.9 THz, all at room-temperature. Terahertz output in these sources originates from intersubband optical nonlinearity in the laser active region. Here we report the first comprehensive spectroscopic study of the optical nonlinearity and investigate its dependence on the mid-infrared pump frequencies. Our work shows that the terahertz generation efficiency can vary by a factor of 2 or greater depending on the spectral position of the mid-infrared pumps for a fixed THz difference-frequency. We have also measured for the first time the linewidth for transitions between the lower quantum cascade laser states, which is critical for determining terahertz nonlinearity and predicting optical loss in quantum cascade laser waveguides. PMID:26879901

  7. Spectroscopic study of partially-ordered semiconductor heterojunction under high pressure and high magnetic field

    SciTech Connect

    Yu, P.Y.; Martinez, G.; Zeman, J.; Uchida, K.

    2000-12-31

    Photoluminescence upconversion (PLU) is a phenomenon in which a sample emits photons with energy higher than that of the excitation photon. This effect has been observed in many materials including rare earth ions doped in insulating hosts and semiconductor heterostructures without using high power lasers as the excitation source. Recently, this effect has been observed also in partially CuPt-ordered GaInP{sub 2} epilayers grown on GaAs substrates. As a spectroscopic technique photoluminescence upconversion is particularly well suited for studying band alignment at heterojunction interface. The value of band-offset has been determined with meV precision using magneto-photoluminescence. Using the fact that the pressure coefficient of electrons in GaAs is higher than those in GaInP{sub 2} they have been able to manipulate the band-offset at the GaInP/GaAs interface. By converting the band-offset from Type I to Type II they were able to demonstrate that the efficiency of the upconversion process is greatly enhanced by a Type II band-offset.

  8. Layered structure of room-temperature ionic liquids in microemulsions by multinuclear NMR spectroscopic studies.

    PubMed

    Falcone, R Dario; Baruah, Bharat; Gaidamauskas, Ernestas; Rithner, Christopher D; Correa, N Mariano; Silber, Juana J; Crans, Debbie C; Levinger, Nancy E

    2011-06-01

    Microemulsions form in mixtures of polar, nonpolar, and amphiphilic molecules. Typical microemulsions employ water as the polar phase. However, microemulsions can form with a polar phase other than water, which hold promise to diversify the range of properties, and hence utility, of microemulsions. Here microemulsions formed by using a room-temperature ionic liquid (RTIL) as the polar phase were created and characterized by using multinuclear NMR spectroscopy. (1)H, (11)B, and (19)F NMR spectroscopy was applied to explore differences between microemulsions formed by using 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF(4)]) as the polar phase with a cationic surfactant, benzylhexadecyldimethylammonium chloride (BHDC), and a nonionic surfactant, Triton X-100 (TX-100). NMR spectroscopy showed distinct differences in the behavior of the RTIL as the charge of the surfactant head group varies in the different microemulsion environments. Minor changes in the chemical shifts were observed for [bmim](+) and [BF(4)](-) in the presence of TX-100 suggesting that the surfactant and the ionic liquid are separated in the microemulsion. The large changes in spectroscopic parameters observed are consistent with microstructure formation with layering of [bmim](+) and [BF(4)](-) and migration of Cl(-) within the BHDC microemulsions. Comparisons with NMR results for related ionic compounds in organic and aqueous environments as well as literature studies assisted the development of a simple organizational model for these microstructures. PMID:21547960

  9. Hunting the parent of the Orphan stream. II. The first high-resolution spectroscopic study

    SciTech Connect

    Casey, Andrew R.; Keller, Stefan C.; Da Costa, Gary; Maunder, Elizabeth; Frebel, Anna

    2014-03-20

    We present the first high-resolution spectroscopic study on the Orphan stream for five stream candidates, observed with the Magellan Inamori Kyocera Echelle spectrograph on the Magellan Clay telescope. The targets were selected from the low-resolution catalog of Casey et al.: three high-probability members, one medium, and one low-probability stream candidate were observed. Our analysis indicates that the low- and medium-probability targets are metal-rich field stars. The remaining three high-probability targets range over ∼1 dex in metallicity, and are chemically distinct compared to the other two targets and all standard stars: low [α/Fe] abundance ratios are observed, and lower limits are ascertained for [Ba/Y], which sit well above the Milky Way trend. These chemical signatures demonstrate that the undiscovered parent system is unequivocally a dwarf spheroidal galaxy, consistent with dynamical constraints inferred from the stream width and arc. As such, we firmly exclude the proposed association between NGC 2419 and the Orphan stream. A wide range in metallicities adds to the similarities between the Orphan stream and Segue 1, although the low [α/Fe] abundance ratios in the Orphan stream are in tension with the high [α/Fe] values observed in Segue 1. Open questions remain before Segue 1 could possibly be claimed as the 'parent' of the Orphan stream. The parent system could well remain undiscovered in the southern sky.

  10. Toward High Performance Graphene-based Solar Cells: Spectroscopic Study on Doped Graphene

    NASA Astrophysics Data System (ADS)

    Chang, Jan-Kai; Hsu, Chen-Chih; Lin, Wei-Hsiang; Wu, Chih-I.; Yeh, Nai-Chang

    2015-03-01

    A polymer-free transfer method with in situ doping process for graphene, aiming at simple and efficient doping of residue-free graphene, has been developed to achieve stacked graphene/dopant intercalation films. The proposed facile strategy led to a tunable work function from 3.25 eV to 5.10 eV, enabling graphene anode and cathode for solar cell devices. Both hybrid and organic photovoltaics using graphene electrodes have been carried out with a series of optimization based on spectroscopic characterizations. Since aging of doped graphene is crucial to the lifetime of graphene-based solar cells, the doping-induced electronic state variation with time has been investigated via X-ray and ultra-violet photoemission spectroscopy analysis to gain insight in its electronic properties and stability. The doping effect developed in graphene has also been studied via Raman spectroscopy, including time evolution of the Raman D, G and 2D bands under normal and humid conditions for up to 30 days. This systematic investigation of aging effect provides better understanding and helps optimize the stacking of doped graphene films for achieving high performance graphene-based devices. This work is supported by NSC of R.O.C. (Dragon Gate Program) and NSF for the work at Caltech.

  11. [NiFe] hydrogenases: structural and spectroscopic studies of the reaction mechanism.

    PubMed

    Ogata, Hideaki; Lubitz, Wolfgang; Higuchi, Yoshiki

    2009-10-01

    [NiFe] hydrogenases catalyze the reversible oxidation of dihydrogen. For this simple reaction the molecule has developed a complex catalytic mechanism, during which the enzyme passes through various redox states. The [NiFe] hydrogenase contains several metal centres, including the bimetallic Ni-Fe active site, iron-sulfur clusters and a Mg(2+) ion. The Ni-Fe active site is located in the inner part of the protein molecule, therefore a number of pathways are involved in the catalytic reaction route. These consist of an electron transfer pathway, a proton transfer pathway and a gas-access channel. Over the last 10-15 years we have been investigating the crystal structures of the [NiFe] hydrogenase from Desulfovibrio vulgaris Miyazaki F, which is a sulfate-reducing anaerobic bacterium. So far the crystal structures of the oxidized, H(2)-reduced and carbon monoxide inhibited states have been determined at high resolution and have revealed a rather unique structure of the hetero-bimetallic Ni-Fe active site. Furthermore, intensive spectroscopic studies have been performed on the enzyme. Based on the crystal structure, a water-soluble Ni-Ru complex has been synthesized as a functional model for the [NiFe] hydrogenases. The present review gives an overview of the catalytic reaction mechanism of the [NiFe] hydrogenases. PMID:19759926

  12. Internal Photoemission and X-Ray Photoelectron Spectroscopic Studies of Sulfur-Passivated GaAs

    NASA Astrophysics Data System (ADS)

    Sato, Kenji; Ikoma, Hideaki

    1993-02-01

    Internal photoemission and X-ray photoelectron spectroscopic (XPS) measurements were performed to investigate the effect of sulfur passivation on the GaAs surface and the degradation of the GaAs surface exposed to air ambient after the passivation. The reverse bias dependence of the Schottky barrier height was very small in the as-sulfur-treated sample and was mainly explained by the image force lowering effect. However, it increased as this sample was exposed to air, indicating an increase in the interface state density. The XPS studies showed that both the Ga and As oxides were hardly observed in the sulfur-passivated samples. This indicates that sulfur passivation strongly suppresses oxidation of GaAs. However, a small amount of elemental arsenic was observed with a trace of the As suboxides (such as AsO) after exposure to air and it increased as the exposure time was increased. These results were probably correlated with the increase in the bias dependence of the Schottky barrier height in samples exposed to air after the passivation. Thermal oxidation of GaAs was found to be retarded by sulfur passivation until oxidation time was about 10 min at 300°C. A possible model of suppression of oxidation by sulfur passivation was also discussed.

  13. ATR-FTIR spectroscopic studies of boric acid adsorption on hydrous ferric oxide

    NASA Astrophysics Data System (ADS)

    Peak, Derek; Luther, George W.; Sparks, Donald L.

    2003-07-01

    Boron is an important micronutrient for plants, but high B levels in soils are often responsible for toxicity effects in plants. It is therefore important to understand reactions that may affect B availability in soils. In this study, Attenuated Total Reflectance Fourier transform Infrared (ATR-FTIR) spectroscopy was employed to investigate mechanisms of boric acid (B(OH) 3) and borate (B(OH) 4-) adsorption on hydrous ferric oxide (HFO). On the HFO surface, boric acid adsorbs via both physical adsorption (outer-sphere) and ligand exchange (inner-sphere) reactions. Both trigonal (boric acid) and tetrahedral (borate) boron are complexed on the HFO surface, and a mechanism where trigonal boric acid in solution reacts to form either trigonal or tetrahedral surface complexes is proposed based upon the spectroscopic results. The presence of outer-sphere boric acid complexes can be explained based on the Lewis acidity of the B metal center, and this complex has important implications for boron transport and availability. Outer-sphere boric acid is more likely to leach downward in soils in response to water flow. Outer-sphere boron would also be expected to be more available for plant uptake than more strongly bound boron complexes, and may more readily return to the soil solution when solution concentrations decrease.

  14. Studies on the interaction of apigenin with calf thymus DNA by spectroscopic methods

    NASA Astrophysics Data System (ADS)

    Zhang, Shufang; Sun, Xuejun; Kong, Rongmei; Xu, Mingming

    2015-02-01

    The interaction between apigenin and calf thymus deoxyribonucleic acid (ctDNA) in a pH 7.4 Tris-HCl buffer solution was investigated by UV-Vis spectroscopy, fluorescence spectroscopy, DNA melting techniques, and viscosity measurements. It was found that apigenin molecules could intercalate into the base pairs of DNA, forming a apigenin-DNA complex with a binding constant of K310K = 6.4 × 104 L mol-1. The thermodynamic parameters enthalpy change (ΔH), entropy change (ΔS) and Gibbs free energy (ΔG) were calculated to be 7.36 × 104 J mol-1, 329 J K-1 mol-1 and -2.84 × 104 J mol-1 at 310 K, respectively. Hydrophobic interaction was the predominant intermolecular force in stabilizing the apigenin-DNA complex. Thermal denaturation study suggested that the stabilization of the ctDNA helix was increased when the apigenin binding to ctDNA as indicated by the increase in thermal denaturation temperature of ctDNA at around 5.0 °C in the presence of apigenin. Spectroscopic techniques together with melting techniques and viscosity determination provided evidences of intercalation mode of binding for the interaction between apigenin and ctDNA.

  15. Spectroscopic studies of metal complexes with redox-active hydrogenated Schiff bases

    NASA Astrophysics Data System (ADS)

    Kasumov, Veli T.

    2001-03-01

    Synthesis and spectroscopic (IR, UV-visible, ESR) characterization of metal(II) complexes M( L'x) 2, (where M=Co(II), NI(II), VO(II), Pd(II), L'x= L' 1, L'2, L'3 are monoanion of unsubstituted, 5-Cl and 5-Br substituted-2-hydroxybenzylamine) with redox-active N-(3,5-ditert-butyl-4-hydroxyphenyl)-2-hydroxybenzylamine ligands as well as radical species generated from these compounds by the oxidation with PbO 2 are reported. ESR studies indicate that the VO( L'x) 2 and Ni( L'x) 2 complexes, in opposite to their salicylaldimine precursors, are more readily oxidized with lead dioxide and results in the formation of the indophenoxyl type stable radical. The formed radical species are very similar to each other and quite different from those of the salicylaldimine analogous according to their g-factors and hyperfine coupling constants. The nine line radical spectra observed in the oxidation of Co( L'x) 2, on standing under vacuum, gradually converted to the signals characteristic of the low-spin Co(II) ( gx,y=2.276, gz=1.998, ACoxy=122.7 G, ACoz=150 G) and radical containing Co(III) intermediate with gx,y=2.015, ACoxy=4.66 G, gz=1.989, ACoz=10 G were also observed.

  16. Spectroscopic, luminescence, electrochemical and antimicrobial studies of lanthanide complexes of bis-benzimidazole derived ligands

    NASA Astrophysics Data System (ADS)

    Siddiqi, Zafar A.; Shahid, Anjuli M.; Khalid, Mohd.; Sharma, Prashant K.; Siddique, Armeen

    2013-04-01

    The lanthanide complexes of [1,2-bis(benzimidazole-2-yl)ethane dihydrochloride], L1·2HCl and [1,4-bis(benzimidazole-2-onium)butane dihydrochloride], L2·2HCl having molecular formulae [Ln(L1)2Cl3H2O] and [Ln(L2)2Cl3H2O]·2H2O (Ln = La3+, Pr3+, Nd3+ and Gd3+), respectively, were prepared and characterized through IR, 1H and 13C NMR, ESI-mass, UV-visible and luminescence spectroscopic techniques. TGA data suggested presence of the coordinated and the lattice water. The oscillator strengths of the f-f transitions and the covalency parameters (β, b1/2 and δ) have been evaluated from the electronic spectral data. The proposed octa coordinate geometry for the complexes has been ascertained from the molecular model computations. CV studies indicate formation of stable quasi-reversible redox couples PrIII/IV, Nd III/IV and GdIII/IV in solution. The in vitro antimicrobial activities of the complexes have been evaluated against gram +ve and gram -ve bacteria and fungi.

  17. Spectroscopic and biological activity studies of the chromium-binding peptide EEEEGDD.

    PubMed

    Arakawa, Hirohumi; Kandadi, Machender R; Panzhinskiy, Evgeniy; Belmore, Kenneth; Deng, Ge; Love, Ebony; Robertson, Preshus M; Commodore, Juliette J; Cassady, Carolyn J; Nair, Sreejayan; Vincent, John B

    2016-06-01

    While trivalent chromium has been shown at high doses to have pharmacological effects improving insulin resistance in rodent models of insulin resistance, the mechanism of action of chromium at a molecular level is not known. The chromium-binding and transport agent low-molecular-weight chromium-binding substance (LMWCr) has been proposed to be the biologically active form of chromium. LMWCr has recently been shown to be comprised of a heptapeptide of the sequence EEEEDGG. The binding of Cr(3+) to this heptapeptide has been examined. Mass spectrometric and a variety of spectroscopic studies have shown that multiple chromic ions bind to the peptide in an octahedral fashion through carboxylate groups and potentially small anionic ligands such as oxide and hydroxide. A complex of Cr and the peptide when administered intravenously to mice is able to decrease area under the curve in intravenous glucose tolerance tests. It can also restore insulin-stimulated glucose uptake in myotubes rendered insulin resistant by treating them with a high-glucose media. PMID:26898644

  18. Spectroscopic Studies of Carotenoid-to-Bacteriochlorophyll Energy Transfer in LHRC Photosynthetic Complex from Roseiflexus castenholzii

    SciTech Connect

    Niedzwiedzki, Dariusz; Collins, Aaron M.; LaFountain, Amy M.; Enriquez, Miriam M.; Frank, Harry A.; Blankenship, R. E.

    2010-06-14

    Carotenoids present in the photosynthetic light-harvesting reaction center (LHRC) complex from chlorosome lacking filamentous anoxygenic phototroph, Roseiflexus castenholzii were purified and characterized for their photochemical properties. The LHRC from anaerobically grown cells contains five different carotenoids, methoxy-keto-myxocoxanthin, γ-carotene, and its three derivatives, whereas the LHRC from aerobically grown cells contains only three carotenoid pigments with methoxy-keto-myxocoxanthin being the dominant one. The spectroscopic properties and dynamics of excited singlet states of the carotenoids were studied by steady-state absorption, fluorescence and ultrafast time-resolved optical spectroscopy in organic solvent and in the intact LHRC complex. Time-resolved transient absorption spectroscopy performed in the near-infrared (NIR) on purified carotenoids combined with steady-state absorption spectroscopy led to the precise determination of values of the energies of the S1(21Ag-) excited state. Global and single wavelength fitting of the ultrafast spectral and temporal data sets of the carotenoids in solvents and in the LHRC revealed the pathways of de-excitation of the carotenoid excited states.

  19. Study of corrosion of super martensitic stainless steel under alternating current in artificial seawater with electrochemical impedance spectroscopy

    SciTech Connect

    Reyes, T.; Bhola, S.; Olson, D. L.; Mishra, B.

    2011-06-23

    The assessment of corrosion requires the use of tools able to quantify the corrosion but often times also qualify it. Electrochemical Impedance Spectroscopy (EIS) is a laboratory tool that can provide both qualification and quantification of corrosion. EIS was successfully used to compare the thickness of the corrosion products formed during the application of different alternating current (AC) densities as well as to characterize pitting. When EIS is applied at the open circuit potential, the technique is nondestructive and predicts the corrosion behavior of the electrode. It can also be used at cathodic potentials while still being nondestructive, providing information about the electrode reaction kinetics, diffusion and electrical double layer.

  20. Methodical study on plaque characterization using integrated vascular ultrasound, strain and spectroscopic photoacoustic imaging

    NASA Astrophysics Data System (ADS)

    Graf, Iulia M.; Su, Jimmy; Yeager, Doug; Amirian, James; Smalling, Richard; Emelianov, Stanislav

    2011-03-01

    Carotid atherosclerosis has been identified as a potential risk factor for cerebrovascular events, but information about its direct effect on the risk of recurrent stroke is limited due to incomplete diagnosis. The combination of vascular ultrasound, strain rate and spectroscopic photoacoustics could improve the timely diagnosis of plaque status and risk of rupturing. Current ultrasound techniques can noninvasively image the anatomy of carotid arteries. The spatio-temporal variation in displacement of different regions within the arterial wall can be derived from ultrasound radio frequency data; therefore an ultrasound based strain rate imaging modality can be used to reveal changes in arterial mechanical properties. Additionally, spectroscopic photoacoustic imaging can provide information on the optical absorption properties of arterial tissue and it can be used to identify the location of specific tissue components, such as lipid pools. An imaging technique combining ultrasound, strain rate and spectroscopic photoacoustics was tested on an excised atherosclerotic rabbit aorta. The ultrasound image illustrates inhomogeneities in arterial wall thickness, the strain rate indicates the arterial segment with reduced elasticity and the spectroscopic photoacoustic image illustrates the accumulation of lipids. The results demonstrated that ultrasound, strain rate and spectroscopic photoacoustic imaging are complementary. Thus the integration of the three imaging modalities advances the characterization of atherosclerotic plaques.

  1. A spectroscopic study of uranyl-cytochrome b5/cytochrome c interactions

    NASA Astrophysics Data System (ADS)

    Sun, Mei-Hui; Liu, Shuang-Quan; Du, Ke-Jie; Nie, Chang-Ming; Lin, Ying-Wu

    2014-01-01

    Uranium is harmful to human health due to its radiation damage and the ability of uranyl ion (UO22+) to interact with various proteins and disturb their biological functions. Cytochrome b5 (cyt b5) is a highly negatively charged heme protein and plays a key role in mediating cytochrome c (cyt c) signaling in apoptosis by forming a dynamic cyt b5-cyt c complex. In previous molecular modeling study in combination with UV-Vis studies, we found that UO22+ is capable of binding to cyt b5 at surface residues, Glu37 and Glu43. In this study, we further investigated the structural consequences of cyt b5 and cyt c, as well as cyt b5-cyt c complex, upon uranyl binding, by fluorescence spectroscopic and circular dichroism techniques. Moreover, we proposed a uranyl binding site for cyt c at surface residues, Glu66 and Glu69, by performing a molecular modeling study. It was shown that uranyl binds to cyt b5 (KD = 10 μM), cyt c (KD = 87 μM), and cyt b5-cyt c complex (KD = 30 μM) with a different affinity, which slightly alters the protein conformation and disturbs the interaction of cyt b5-cyt c complex. Additionally, we investigated the functional consequences of uranyl binding to the protein surface, which decreases the inherent peroxidase activity of cyt c. The information of uranyl-cyt b5/cyt c interactions gained in this study likely provides a clue for the mechanism of uranyl toxicity.

  2. Calibration of electrical impedance tomography

    SciTech Connect

    Daily, W; Ramirez, A

    2000-05-01

    Over the past 10 years we have developed methods for imaging the electrical resistivity of soil and rock formations. These technologies have been called electrical resistance tomography of ERT (e.g. Daily and Owen, 1991). Recently we have been striving to extend this capability to include images of electric impedance--with a new nomenclature of electrical impedance tomography or EIT (Ramirez et al., 1999). Electrical impedance is simply a generalization of resistance. Whereas resistance is the zero frequency ratio of voltage and current, impedance includes both the magnitude and phase relationship between voltage and current at frequency. This phase and its frequency behavior is closely related to what in geophysics is called induced polarization or (Sumner, 1976). Why is this phase or IP important? IP is known to be related to many physical phenomena of importance so that image of IP will be maps of such things as mineralization and cation exchange IP (Marshall and Madden, 1959). Also, it is likely that IP, used in conjunction with resistivity, will yield information about the subsurface that can not be obtained by either piece of information separately. In order to define the accuracy of our technologies to image impedance we have constructed a physical model of known impedance that can be used as a calibration standard. It consists of 616 resistors, along with some capacitors to provide the reactive response, arranged in a three dimensional structure as in figure 1. Figure 2 shows the construction of the network and defines the coordinate system used to describe it. This network of components is a bounded and discrete version of the unbounded and continuous medium with which we normally work (the subsurface). The network has several desirable qualities: (1) The impedance values are known (to the accuracy of the component values). (2) The component values and their 3D distribution is easily controlled. (3) Error associated with electrode noise is eliminated. (4

  3. A Combined theoretical and experimental study of conformational and spectroscopic profile of 2-acetamido-5-aminopyridine.

    PubMed

    Pathak, Shilendra K; Srivastava, Ruchi; Sachan, Alok K; Prasad, Onkar; Sinha, Leena

    2015-05-15

    Present work aims at identifying the conformational and spectroscopic profile of 2-acetamido-5-aminopyridine compound by means of experimental and computational methods. To achieve this, three-dimensional potential energy scan (PES) was performed by varying the selected dihedral angles at B3LYP/6-31+G(d,p) level of theory and thus stable conformers of the title compound were determined. The most stable conformer was further optimized at higher level and vibrational wavenumbers were calculated. Experimentally, vibrational features of title compound were determined by FT-IR and FT-Raman spectroscopic methods in the solid phase while the electronic absorption spectrum was recorded in methanol solution. On the basis of these investigations, the conformational and spectroscopic attributes of 2-acetamido-5-aminopyridine were interpreted. PMID:25725210

  4. A Combined theoretical and experimental study of conformational and spectroscopic profile of 2-acetamido-5-aminopyridine

    NASA Astrophysics Data System (ADS)

    Pathak, Shilendra K.; Srivastava, Ruchi; Sachan, Alok K.; Prasad, Onkar; Sinha, Leena

    2015-05-01

    Present work aims at identifying the conformational and spectroscopic profile of 2-acetamido-5-aminopyridine compound by means of experimental and computational methods. To achieve this, three-dimensional potential energy scan (PES) was performed by varying the selected dihedral angles at B3LYP/6-31+G(d,p) level of theory and thus stable conformers of the title compound were determined. The most stable conformer was further optimized at higher level and vibrational wavenumbers were calculated. Experimentally, vibrational features of title compound were determined by FT-IR and FT-Raman spectroscopic methods in the solid phase while the electronic absorption spectrum was recorded in methanol solution. On the basis of these investigations, the conformational and spectroscopic attributes of 2-acetamido-5-aminopyridine were interpreted.

  5. Quantification of Inlet Impedance Concept and a Study of the Rayleigh Formula for Noise Radiation from Ducted Fan Engines

    NASA Technical Reports Server (NTRS)

    Posey, Joe W.; Dunn, M. H.; Farassat, F.

    2004-01-01

    This paper addresses two aspects of duct propagation and radiation which can contribute to more efficient fan noise predictions. First, we assess the effectiveness of Rayleigh's formula as a ducted fan noise prediction tool. This classical result which predicts the sound produced by a piston in a flanged duct is expanded to include the uniform axial inflow case. Radiation patterns using Rayleigh's formula with single radial mode input are compared to those obtained from the more precise ducted fan noise prediction code TBIEM3D. Agreement between the two methods is excellent in the peak noise regions both forward and aft. Next, we use TBIEM3D to calculate generalized radiation impedances and power transmission coefficients. These quantities are computed for a wide range of operating parameters. Results were obtained for higher Mach numbers, frequencies, and circumferential mode orders than have been previously published. Viewed as functions of frequency, calculated trends in lower order inlet impedances and power transmission coefficients are in agreement with known results. The relationships are more oscillatory for higher order modes and higher Mach numbers.

  6. Spectroscopic Studies of Atomic and Molecular Processes in the Edge Region of Magnetically Confined Fusion Plasmas

    SciTech Connect

    Hey, J. D.; Brezinsek, S.; Mertens, Ph.; Unterberg, B.

    2006-12-01

    Edge plasma studies are of vital importance for understanding plasma-wall interactions in magnetically confined fusion devices. These interactions determine the transport of neutrals into the plasma, and the properties of the plasma discharge. This presentation deals with optical spectroscopic studies of the plasma boundary, and their role in elucidating the prevailing physical conditions. Recorded spectra are of four types: emission spectra of ions and atoms, produced by electron impact excitation and by charge-exchange recombination, atomic spectra arising from electron impact-induced molecular dissociation and ionisation, visible spectra of molecular hydrogen and its isotopic combinations, and laser-induced fluorescence (LIF) spectra. The atomic spectra are strongly influenced by the confining magnetic field (Zeeman and Paschen-Back effects), which produces characteristic features useful for species identification, temperature determination by Doppler broadening, and studies of chemical and physical sputtering. Detailed analysis of the Zeeman components in both optical and LIF spectra shows that atomic hydrogen is produced in various velocity classes, some related to the relevant molecular Franck-Condon energies. The latter reflect the dominant electron collision processes responsible for production of atoms from molecules. This assignment has been verified by gas-puffing experiments through special test limiters. The higher-energy flanks of hydrogen line profiles probably also show the influence of charge-exchange reactions with molecular ions accelerated in the plasma sheath ('scrape-off layer') separating limiter surfaces from the edge plasma, in analogy to acceleration in the cathode-fall region of gas discharges. While electron collisions play a vital role in generating the spectra, ion collisions with excited atomic radiators act through re-distribution of population among the atomic fine-structure sublevels, and momentum transfer to the atomic nuclei via

  7. Manipulating the proton transfer process in molecular complexes: synthesis and spectroscopic studies.

    PubMed

    Panja, Sumit Kumar; Dwivedi, Nidhi; Saha, Satyen

    2016-08-01

    The proton transfer process in carefully designed molecular complexes has been investigated directly in the solid and solution phase. SCXRD studies have been employed to investigate the N-H-O bonding interaction sites of the molecular complexes, with additional experimental support from FTIR and Raman spectroscopic studies, to gain information on the relative position of hydrogen in between the N and O centers. Further, the proton transfer process in solution is studied using UV-Visible spectroscopy through monitoring the intramolecular charge transfer (ICT) process in these molecular complexes, which is primarily governed by the number of electron withdrawing groups (nitro groups) on proton donor moieties (NP, DNP and TNP). It is found that the magnitude of the ICT process depends on the extent of proton transfer, which on the other hand depends on the relative stabilities of the constituent species (phenolate species). A correlation is observed between an increase in the number of nitro groups and an increase in the melting point of the molecular complexes, indicating the enhancement of ionic character due to the proton transfer process. The aliphatic H-bonding is identified and monitored using (1)H-NMR spectroscopy, which reveals that the identity of molecular complexes in solution interestingly depends on the extent of proton transfer, in addition to the nature of the solvents. The aliphatic C-H-O H-bonding interaction between the oxygen atom of the nitro group and the alkyl hydrogen in piperidinium was also found to play a significant role in strengthening the primary interaction involving a hydrogen transfer process. The conductivity of the molecular complexes increases with an increase in the number of nitro groups, indicating the enhancement in ionic character of the molecular complexes. PMID:27424765

  8. Optical properties of As33S67-xSex bulk glasses studied by spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Orava, J.; Šik, J.; Wágner, T.; Frumar, M.

    2008-04-01

    Variable angle spectroscopic ellipsometry (VASE) was employed to study the optical properties of As33S67-xSex (x =0, 17, 33.5, 50, and 67at.%) bulk glasses in the UV-vis-NIR (near infrared) spectral region for photon energies from 0.54to4.13eV (photon wavelengths from 2300to300nm). For data analysis, we employed Tauc-Lorentz (TL) dispersion model in the entire measured near bandgap spectral region and standard Cauchy dispersion model in the spectral region below the bandgap. With increasing Se content (x) in the bulk glass, we observed a linear decrease in optical bandgap energy Egopt from 2.52±0.02eV for As33S67 to 1.75±0.01eV for As33Se67 and linear increase in refractive index nTL in the NIR spectral region, e.g., at 0.80eV from 2.327 for As33S67 to 2.758 for As33Se67. The amplitude A decreased with increasing Se content. The peak transition energy E0 and broadening C had a maximum value for x =33.5at.% and systematically decreased for higher S or Se content in glasses. Our study showed that TL model is suitable to describe dielectric functions of studied chalcogenide bulk glasses in the broad spectral region. The bulk glasses had a higher refractive index compared to thin films of corresponding composition. The bulk glasses with high S content had higher value of optical bandgap energy than was previously reported for thin films. The optical bandgap energy of glasses with higher Se content was very similar to the thin films.

  9. Line narrowing spectroscopic studies of DNA-carcinogen adducts and DNA-dye complexes

    SciTech Connect

    Suh, Myungkoo

    1995-12-06

    Laser-induced fluorescence line narrowing and non-line narrowing spectroscopic methods were applied to conformational studies of stable DNA adducts of the 7{beta}, 8{alpha}-dihydoxy-9{alpha}, l0{alpha}-epoxy-7,8,9, 10-tetrahydrobenzo[{alpha}]pyrene (anti-BPDE). Stereochemically distinct (+)-trans-, ({minus})-trans-, (+)-cis- and ({minus})-cis adducts of anti-BPDE bound to exocyclic amino group of the central guanine in an 11-mer oligonucleotide, exist in a mixture of conformations in frozen aqueous buffer matrices. The (+)-trans adduct adopts primarily an external conformation with a smaller fraction ( {approximately} 25 %) exists in a partially base-stacked conformation. Both cis adducts were found to be intercalated with significant {pi}-{pi} stacking interactions between the pyrenyl residues and the bases. Conformations of the trans-adduct of (+)-anti -BPDE in 11-mer oligonucleotides were studied as a function of flanking bases. In single stranded form the adduct at G{sub 2} or G{sub 3} (5 ft-flanking, base guanine) adopts a conformation with strong, interaction with the bases. In contrast, the adduct with a 5ft-flanking, thymine exists in a primarily helixexternal conformation. Similar differences were observed in the double stranded oligonucleotides. The nature of the 3ft-flanking base has little influence on the conformational equilibrium of the (+)-trans-anti BPDE-dG adduct. The formation and repair of BPDE-N{sup 2}-dG in DNA isolated from the skin of mice treated topically with benzo[{alpha}]pyrene (BP) was studied. Low-temperature fluorescence spectroscopy of the intact DNA identified the major adduct as (+)-trans-anti-BPDE-N-dG, and the minor adduct fraction consisted mainly of (+)-cis-anti-BPDE-N{sup 2}-dG.

  10. The origin, composition and history of cometary ices from spectroscopic studies

    NASA Technical Reports Server (NTRS)

    Allamandola, L. J.

    1989-01-01

    The spectroscopic analysis of pristine cometary material provides a very important probe of the chemical identity of the material as well as of the physical and chemical conditions which prevailed during the comet's history. Concerning classical spectroscopy, the spectral regions which will most likely prove most useful are the infrared, the visible and ultraviolet. Newer spectroscopic techniques which have the potential to provide equally important information include nuclear magnetic resonance (NMR) and electron spin resonance (ESR). Each technique is summarized with emphasis placed on the kind of information which can be obtained.

  11. Synthesis, spectroscopic characterization and comparative DNA binding studies of Schiff base complexes derived from L-leucine and glyoxal

    NASA Astrophysics Data System (ADS)

    Shakir, Mohammad; Shahid, Nida; Sami, Naushaba; Azam, Mohammad; Khan, Asad U.

    2011-11-01

    The mononuclear Schiff base complexes of the type, [ML(CH 3OH) 2] [M = Co(II), Ni(II), Cu(II) and Zn(II)] have been synthesized by template condensation of L-leucine and glyoxal. The complexes have been characterized on the basis of the results of the elemental analysis, molar conductance, magnetic susceptibility measurements and spectroscopic studies viz, FT-IR, Mass, 1H NMR and 13C NMR spectra. The UV-vis and magnetic moment data revealed an octahedral geometry around Co(II), Ni(II) ion with distortion around Cu(II) ion complex confirmed by EPR data. The conductivity data show a non-electrolytic nature of the complexes. Absorption and fluorescence spectroscopic studies support that all the complexes exhibit a significant binding to calf thymus DNA.

  12. Flow time through esophagogastric junction derived during high-resolution impedance-manometry studies: a novel parameter for assessing esophageal bolus transit

    PubMed Central

    Lin, Zhiyue; Imam, Hala; Nicodème, Frèdèric; Carlson, Dustin A.; Lin, Chen-Yuan; Yim, Brandon; Kahrilas, Peter J.

    2014-01-01

    This study aimed to develop and validate a method to measure bolus flow time (BFT) through the esophagogastric junction (EGJ) using a high-resolution impedance-manometry (HRIM) sleeve. Ten healthy subjects were studied with concurrent HRIM and videofluoroscopy; another 15 controls were studied with HRIM alone. HRIM studies were performed using a 4.2-mm-outer diameter assembly with 36 pressure sensors at 1-cm intervals and 18 impedance segments at 2-cm intervals (Given Imaging, Los Angeles, CA). HRIM and fluoroscopic data from four barium swallows, two in the supine and two in the upright position, were analyzed to create a customized MATLAB program to calculate BFT using a HRIM sleeve comprising three sensors positioned at the crural diaphragm. Bolus transit through the EGJ measured during blinded review of fluoroscopy was almost identical to BFT calculated with the HRIM sleeve, with the nadir impedance deflection point used as the signature of bolus presence. Good correlation existed between videofluoroscopy for measurement of upper sphincter relaxation to beginning of flow [R = 0.97, P < 0.001 (supine) and R = 0.77, P < 0.01 (upright)] and time to end of flow [R = 0.95, P < 0.001 (supine) and R = 0.82, P < 0.01 (upright)]. The medians and interquartile ranges (IQR) of flow time though the EGJ in 15 healthy subjects calculated using the virtual sleeve were 3.5 s (IQR 2.3–3.9 s) in the supine position and 3.2 s (IQR 2.3–3.6 s) in the upright position. BFT is a new metric that provides important information about bolus transit through the EGJ. An assessment of BFT will determine when the EGJ is open and will also provide a useful method to accurately assess trans-EGJ pressure gradients during flow. PMID:24852565

  13. Flow time through esophagogastric junction derived during high-resolution impedance-manometry studies: a novel parameter for assessing esophageal bolus transit.

    PubMed

    Lin, Zhiyue; Imam, Hala; Nicodème, Frèdèric; Carlson, Dustin A; Lin, Chen-Yuan; Yim, Brandon; Kahrilas, Peter J; Pandolfino, John E

    2014-07-15

    This study aimed to develop and validate a method to measure bolus flow time (BFT) through the esophagogastric junction (EGJ) using a high-resolution impedance-manometry (HRIM) sleeve. Ten healthy subjects were studied with concurrent HRIM and videofluoroscopy; another 15 controls were studied with HRIM alone. HRIM studies were performed using a 4.2-mm-outer diameter assembly with 36 pressure sensors at 1-cm intervals and 18 impedance segments at 2-cm intervals (Given Imaging, Los Angeles, CA). HRIM and fluoroscopic data from four barium swallows, two in the supine and two in the upright position, were analyzed to create a customized MATLAB program to calculate BFT using a HRIM sleeve comprising three sensors positioned at the crural diaphragm. Bolus transit through the EGJ measured during blinded review of fluoroscopy was almost identical to BFT calculated with the HRIM sleeve, with the nadir impedance deflection point used as the signature of bolus presence. Good correlation existed between videofluoroscopy for measurement of upper sphincter relaxation to beginning of flow [R = 0.97, P < 0.001 (supine) and R = 0.77, P < 0.01 (upright)] and time to end of flow [R = 0.95, P < 0.001 (supine) and R = 0.82, P < 0.01 (upright)]. The medians and interquartile ranges (IQR) of flow time though the EGJ in 15 healthy subjects calculated using the virtual sleeve were 3.5 s (IQR 2.3-3.9 s) in the supine position and 3.2 s (IQR 2.3-3.6 s) in the upright position. BFT is a new metric that provides important information about bolus transit through the EGJ. An assessment of BFT will determine when the EGJ is open and will also provide a useful method to accurately assess trans-EGJ pressure gradients during flow. PMID:24852565

  14. A New Optical Cell for Spectroscopic Studies of Geofluids at Pressures up to 100 MPa

    NASA Astrophysics Data System (ADS)

    Chou, I.; Burruss, R. C.

    2003-12-01

    Interpretation of Raman and fluorescence spectra of hydrocarbon fluid inclusions and spectroscopic observations of reactions in hydrocarbon-water systems require high quality reference spectra of individual gases, gas mixtures, and hydrocarbon-water systems. We constructed a new optical cell from a square flexible fused silica capillary tube (300 μ m x 300 μ m with 100 μ m x 100 μ m cavity) and a high-pressure valve that allows studies of fluids at room temperature and pressures up to 100 MPa. The cell has several advantages over existing ones, including the hydrothermal diamond-anvil cell, and they are: (1) ability to directly load sample fluids and monitor pressure during investigation; (2) no optical distortion; (3) small cell volume suitable for samples of limited supply (e.g., commercially available gas mixtures); (4) high pressures can be achieved; (5) a high-magnification, high-numerical-aperture objective lens (e.g., 100x) with a short working distance can be used due to the thin wall of the capillary tube, and (6) a heating-cooling stage can be added, allowing for investigations at temperatures other than room temperature, particularly suitable for studies of gas hydrates. Raman spectra have been collected from the cell for methane, ethane, propane, n-butane, and also for two gas mixtures containing up to 9 components as a function of pressure up to 41 MPa. The spectra document the shift in Raman bands with pressure as well as constrain the detection limits for various gas species in the mixtures. Preliminary experiments on the diffusion of methane in water were conducted by monitoring the concentration of dissolved methane in water, as a function of time and distance from the vapor-water boundary, immediately after the perturbation of an equilibrium state induced by a sudden change in methane pressure.

  15. Optical and other spectroscopic studies of lead, zinc bismuth borate glasses doped with CuO

    NASA Astrophysics Data System (ADS)

    Rajyasree, Ch.; Vinaya Teja, P. Michael; Murthy, K. V. R.; Krishna Rao, D.

    2011-12-01

    10MO·20Bi2O3·(70-x)B2O3·xCuO [M=Pb, Zn] with x=0, 0.4 and 0.8 (wt%) glasses were synthesized by the melt-quenching technique and were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. Physical parameters, like density, and spectroscopic studies (optical absorption, EPR, FTIR and photoluminescence) were used to understand the role of modifier oxide and CuO in the glass matrix. A red shift of the absorption band corresponds to 2B1g→2B2g transition of Cu2+ ions from P2 to Z4 samples and the increase of hyperfine splitting factor (A‖) from P2 to Z2 shows that with the integration of PbO by ZnO the electron density around copper ion is increased. It is also supported by the gradual increase in theoretical optical basicity values of ZnO mixed glasses, as compared to that of PbO mixed glass matrix. Reduced bismuth radicals are found in undoped and 0.4% CuO doped glasses of both the series. Analysis of the absorption and emission studies indicates that the concentration of luminescence centers of bismuth ions (Bi3+ ions in UV region) is decreased by the integration of ZnO as well as by increasing the dopant concentration. In lead series PbO4 and BiO3 units are increased from P2 to P4 and in zinc series BiO3 units are decreased from Z0 to Z4. The conductivity of the glass matrices is increased in both the series with the dopant of CuO.

  16. Spectroscopic and quantum chemical study of the structure of a new paramagnetic dimeric palladium(II,III) complex with creatine

    NASA Astrophysics Data System (ADS)

    Mitewa, Mariana; Enchev, Venelin; Bakalova, Tatyana

    2002-05-01

    The structure and coordination mode of the newly synthesized dimeric paramagnetic Pd(II,III) complex are studied using magneto-chemical, EPR and IR spectroscopic methods. In order to perform reliable assignment of the IR bands, the structure and IR spectrum of the free creatine were calculated using ab initio method. For calculation of the configuration of its deprotonated and doubly deprotonated forms the semiempirical AM1 method was used.

  17. Summary of the impedance working group

    SciTech Connect

    Chao, A.W.

    1995-05-01

    The impedance working group concentrated on the LHC design during the workshop. They look at the impedance contributions of liner, beam position monitors, shielded bellows, experimental chambers, superconducting cavities, recombination chambers, space charge, kickers, and the resistive wall. The group concluded that the impedance budgeting and the conceptual designs of the vacuum chamber components looked basically sound. It also noted, not surprisingly, that a large amount of studies are to be carried out further, and it ventured to give a partial list of these studies.

  18. Impedance Alterations in Healthy and Diseased Mice During Electrically Induced Muscle Contraction.

    PubMed

    Sanchez, Benjamin; Li, Jia; Geisbush, Tom; Bardia, Ramon Bragos; Rutkove, Seward B

    2016-08-01

    Alterations in the health of muscles can be evaluated through the use of electrical impedance myography (EIM). To date, however, nearly all work in this field has relied upon the measurement of muscle at rest. To provide an insight into the contractile mechanisms of healthy and disease muscle, we evaluated the alterations in the spectroscopic impedance behavior of muscle during the active process of muscle contraction. The gastrocnemii from a total of 13 mice were studied (five wild type, four muscular dystrophy animals, and four amyotrophic lateral sclerosis animals). Muscle contraction was induced via monophasic current pulse stimulation of the sciatic nerve. Simultaneously, multisine EIM (1 kHz to 1 MHz) and force measurements of the muscle were performed. Stimulation was applied at three different rates to produce mild, moderate, and strong contractions. We identified changes in both single and multifrequency data, as assessed by the Cole impedance model parameters. The processes of contraction and relaxation were clearly identified in the impedance spectra and quantified via derivative plots. Reductions in the center frequency fc were observed during the contraction consistent with the increasing muscle fiber diameter. Different EIM stimulation rate-dependencies were also detected across the three groups of animals. PMID:24800834

  19. Photoelectron, nuclear gamma-ray and infrared absorption spectroscopic studies of neptunium in sodium silicate glass

    SciTech Connect

    Veal, B.W.; Carnall, W.T.; Dunlap, B.D.; Mitchell, A.W.; Lam, D.J.

    1986-04-01

    The valence state of neptunium ions in sodium silicate glasses prepared under reducing and oxidizing conditions has been investigated by the x-ray photoelectron, Moessbauer and optical absorption spectroscopic techniques. Results indicate that the Np ions are tetravalent in glasses prepared under reducing conditions and pentavalent in glasses prepared under oxidizing conditions.

  20. AB Initio Study of the Structure and Spectroscopic Properties of Halogenated Thioperoxy Radicals

    NASA Technical Reports Server (NTRS)

    Munoz, Luis A.; Binning, R. C., Jr.; Weiner, Brad R.; Ishikawa, Yasuyuki

    1997-01-01

    Thioperoxy (XSO or XOS) radicals exist in a variety of chemical environments, and they have as a consequence drawn some interest. HSO, an important species in the chemistry of the troposphere, has been examined both experimentally. The halogenated (X = F, Cl or Br) peroxy species and isovalent thioperoxy species have been studied less, but they too are potentially interesting because oxidized sulfur species and halogen sources are present in the atmosphere. Learning the fate of XSO and XOS radicals is important to understanding the atmospheric oxidation chemistry of sulfur compounds. Of these, FSO and ClSO are particularly interesting because they have been directly detected spectroscopically. Recent studies in our laboratory on the photochemistry of thionyl halides (X2SO; where X = F or Cl) have suggested new ways to generate XSO species. The laser-induced photodissociation of thionyl fluoride, F2SO, at 193 nm and thionyl chloride, ClSO, at 248 nm is characterized by a radical mechanism, X2SO -> XSO + X. The structure of FSO has been characterized experimentally by Endo et cd. employing microwave spectroscopy. Using the unrestricted Hartree-Fock (UHF) self-consistent field (SCF) method, Sakai and Morokuma computed the electronic structure of the ground (sup 2)A" and the first excited (sup 2)A' states of FSO. Electron correlation was not taken into account in their study. In a laser photodissociation experiment, Huber et al. identified ClSO mass spectromctrically. ClSO has also been detected in low temperature matrices by EPR and in the gas phase by far IR laser magnetic resonance. Although the structure of FSO is known in detail, the only study, experimental or theoretical, of CISO has been an ab initio HFSCF study by Hinchliffe. Electron correlation corrections were also excluded from this study. In order to better understand the isomerization and dissociation dynamics of the radical species, we have performed ab initio correlated studies of the potential energy