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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. Laser Raman and ac impedance spectroscopic studies of PVA: NH 4NO 3 polymer electrolyte

    NASA Astrophysics Data System (ADS)

    Hema, M.; Selvasekarapandian, S.; Hirankumar, G.; Sakunthala, A.; Arunkumar, D.; Nithya, H.

    2010-01-01

    Ion conducting polymer electrolyte PVA:NH 4NO 3 has been prepared by solution casting technique and characterized using XRD, Raman and ac impedance spectroscopic analyses. The amorphous nature of the polymer films has been confirmed by XRD and Raman spectroscopy. An insight into the deconvoluted Raman peaks of υ1 vibration of NO 3- anion for the polymer electrolyte reveals the dominancy of ion aggregates at higher NH 4NO 3 concentration. From the ac impedance studies, the highest ion conductivity at 303 K has been found to be 7.5 × 10 -3 S cm -1 for 80PVA:20NH 4NO 3. The conductivity of the polymer electrolytes has been found to depend on the degree of dissociation of the salt in the host polymer matrix. The combination of the above-mentioned analyses has proven worth while and in fact necessary in order to achieve better understanding of these complex systems.

  4. Interdigitated microelectrode-based microchip for electrical impedance spectroscopic study of oral cancer cells.

    PubMed

    Mamouni, Jaouad; Yang, Liju

    2011-12-01

    In this study, electric/electrochemical impedance spectroscopy and cyclic voltammetry were used to study the cellular activities of oral cancer cell line CAL 27, including the kinetics of cell adhesion, spreading, and cell proliferation on interdigitated microelectrodes (IMEs). Impedance spectra of CAL 27 cells on IMEs electrodes were obtained in cell growth medium and in 0.1 M PBS with 50 mM [Fe(CN)₆]³⁻/⁴⁻ as redox probe. Equivalent circuits were used to model both cases. In cell growth medium, impedance spectra allowed us to analyze the changes in capacitance and resistance due to cell attachment on the IMEs over the entire experiment period. It was found that cell spreading caused the most significant decrease in capacitance component and slight increase in resistance component. Impedance change at given frequencies (between 10 kHz to 100 kHz) was found to be linearly increased with increasing cell number of CAL 27 on the IMEs. In comparison with non-cancer oral epithelial cells (Het-1A), at equal cell number, cancer cells always generated impedance several folds higher than that of non-cancer cells. In the presence of [Fe(CN)₆]³⁻/⁴⁻, impedance spectra allowed us to analyze the change in electron transfer resistance of IMEs due to cell attachment, in which an increase trend was observed at 24 h with increasing cell number from 2500 cells to 10,000 cells on IMEs. Double layer capacitance was also affected by cell attachment, and a decrease in double layer capacitance was observed with increasing cell number on the electrodes. Cyclic voltammetric measurements correlated well with the impedance results. The results of this study demonstrated the use of electrochemical approaches to obtain and understand cellular behaviors/activities of oral cancer cells, potentially providing useful tools for cancer cell research.

  5. Impedance Spectroscopic Studies of BiFeO3-Pb(ZrTi)O3 Nanocomposites

    NASA Astrophysics Data System (ADS)

    Choudhary, R. N. P.; Barik, Subrat K.; Katiyar, R. S.

    BiFeO3-Pb(ZrTi)O3 [i.e., (Bi1-xPbx)(Fe1-xZr0.6xTi0.4x)O3 (x = 0.15, 0.25, 0.40, 0.50)] nanocomposites were synthesized using mechanical activation followed by a solid-state reaction technique. The dielectric parameters (capacitance, dissipation factor D, impedance Z and phase angle Φ) of all the samples were measured in a wide range of frequencies (1 kHz-1 MHz) and temperatures (300-630 K) in air atmosphere using an impedance analyzer with low signal amplitude of 500 mV. Electrical properties of the compounds were studied using a complex impedance spectroscopy (CIS) technique. The frequency dependence of electrical data was analyzed in the framework of conductivity and modulus formalisms. AC conductivity spectrum obeys Jonscher's universal power law.

  6. 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.

  7. Structural and complex impedance spectroscopic studies of Ni0.5Mg0.3Cu0.2Fe2O4 ferrite nanoparticle

    NASA Astrophysics Data System (ADS)

    Dhaou, Mohamed Houcine; Hcini, Sobhi; Mallah, Abdulrahman; Bouazizi, Mohamed Lamjed; Jemni, Abdelmajid

    2017-01-01

    Spinel ferrite having composition Ni0.5Mg0.3Cu0.2Fe2O4 was prepared by the sol-gel technique at 1473 K. The X-ray diffraction results indicate that the ferrite sample has a cubic spinel-type structure with Fdbar{3}m space group. The electrical properties of the studied sample using complex impedance spectroscopy technique have been investigated in the frequency range 102-107 Hz and in the temperature range 300-500 K. The total conductivity curves for sample are found to obey Jonscher power law ( σ( ω) = σ dc + Aω n ) with an increase in the frequency exponent ( n) as temperature increases. The activation energy deduced from the analysis of the conductivity curves matches very well with the value estimated from the relaxation time, indicating that relaxation process and electrical conductivity are attributed to the same defect. Nyquist plots of impedance show semicircle arcs for sample, and an electrical equivalent circuit has been proposed to explain the impedance results. The effect of frequency and temperature on dielectric constant ( ɛ″) and dielectric loss (tan δ) has also been discussed in terms of hopping of charge carriers between Fe2+ and Fe3+ ions.

  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. Structural and complex AC impedance spectroscopic studies of A 2CoNbO 6 (A = Sr, Ba) ordered double perovskites

    NASA Astrophysics Data System (ADS)

    Bashir, J.; Shaheen, R.

    2011-05-01

    Powder X-ray diffraction has been employed to study the crystal structures of Sr 2CoNbO 6 ( SCNO) and Ba 2CoNbO 6 ( BCNO) double perovskites. Rietveld fit to the X-ray diffraction data showed that Ba 2CoNbO 6 perovskites was monoclinic with space group P2 1/ n whereas Sr 2CoNbO 6 was found to be tetragonal with space group I4/ m. Like other cobalt based perovskites, both materials exhibit high values of dielectric constant at room temperature and low frequencies. Room temperature impedance and modulus spectra, measured over the 1 Hz to 10 MHz, reveal two relaxation processes with different relaxation times which were attributed to the grain and grain boundaries.

  10. Electrochemical Impedance Spectroscopic Sensing of Methamphetamine by a Specific Aptamer

    PubMed Central

    Ebrahimi, Mohsen; Johari-Ahar, Mohammad; Hamzeiy, Hossein; Barar, Jaleh; Mashinchian, Omid; Omidi, Yadollah

    2012-01-01

    Introduction Electrochemical impedance spectroscopy (EIS) is a simple and highly sensitive technique that can be used for evaluation of the aptamer-target interaction even in a label-free approach. Methods To pursue the effectiveness of EIS, in the current study, the folding properties of specific aptamer for methamphetamine (METH) (i.e., aptaMETH) were evaluated in the presence of METH and amphetamine (Amph). Folded and unfolded aptaMETH was mounted on the gold electrode surface and the electron charge transfer was measured by EIS. Results The Ret of methamphetamine-aptaMETH was significantly increased in comparison with other folding conditions, indicating specific detection of METH by aptaMETH. Conclusion Based on these findings, methamphetamine-aptaMETH on the gold electrode surface displayed the most interfacial electrode resistance and thus the most folding situation. This clearly indicates that the aptaMETH can profoundly and specifically pinpoint METH; as a result we suggest utilization of this methodology for fast and cost-effective identification of METH. PMID:23678446

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

    NASA Astrophysics Data System (ADS)

    Timalsina, Yukta P.; Branen, Joshua; Aston, D. Eric; Noren, Kenneth; Corti, Giancarlo; Schumacher, Randi; McIlroy, David N.

    2011-07-01

    In this study, alternating current impedance spectroscopic analysis of the biofunctionalization process of a vertically-aligned (silica) nanosprings (VANS) surface is presented. The VANS surface is functionalized with a biotinylated immunoglobulin G (B-IgG) layer formed by physisorption of B-IgG from the solution phase. Bovine serum albumin passivation of the B-IgG layer reduces additional surface adsorption by blocking the potential sites of weak bond formation via electrostatic and hydrophobic interactions. As avidin acts as a receptor of biotinylated compounds, avidin conjugated glucose oxidase (Av-GOx) binds to the B-IgG layer via biotin. This avidin-biotin bond is a stable bond with high association affinity (Ka = 1015 M-1) that withstands wide variations in chemistry and pH. An IgG layer without biotin shows no binding to the Av-GOx, indicating that bonding is through the avidin-biotin interaction. Finally, fluoroscein iso-thiocyanate (FITC) labeled biotinylated bovine serum albumin (B-BSA) added to the Av-GOx surface is used to fluorescently label Av-GOx for fluorescent measurements that allow for the correlation of surface binding with impedance measurements. Modeling of impedance spectra measured after the addition of each biological solution indicates that the bimolecular layers behave as insulating layers. The impedance spectra for the VANS-based sensor are compared to simple parallel capacitor sensors, sans VANS, and serve as controls. VANS-based sensors exhibit a greater magnitude of change between successive bio-layers relative to the controls below 10 kHz. Changes in the magnitudes of the components of the VANS equivalent circuit indicate that the addition of biological layers changes the effective dielectric response of the VANS via the impediment of ionic motion and biomolecule polarization.

  12. Impedance spectroscopic analysis of nanoparticle functionalized graphene/p-Si Schottky diode sensors

    NASA Astrophysics Data System (ADS)

    Uddin, Md Ahsan; Singh, Amol; Daniels, Kevin; Vogt, Thomas; Chandrashekhar, M. V. S.; Koley, Goutam

    2016-11-01

    Metallic nanoparticle (NP) functionalized graphene/p-Si Schottky diode (chemidiode) sensors have been investigated through dc amperometric and ac impedance spectroscopic (IS) measurements. Four fold sensitivity enhancement for NH3 is demonstrated after Pt nanoparticle functionalization of graphene/p-Si Schottky diode sensor, and the response is also orders of magnitude higher compared to functionalized graphene chemiresistor. Experimentally obtained impedance spectra were modeled utilizing an equivalent circuit for both sensor types, and the junction resistance and capacitance were extracted for various gaseous analytes exposure. Variations in junction resistance, capacitance and 3-dB cut-off frequency plotted in three-dimensional (3D) enables extraction of unique signatures for various analyte gases.

  13. Electrochemical impedance spectroscopic measurements of FCCP-induced change in membrane permeability of MDCK cells.

    PubMed

    Zhao, Lingzhi; Li, Xianchan; Lin, Yuqing; Yang, Lifen; Yu, Ping; Mao, Lanqun

    2012-05-07

    This study demonstrates a new electrochemical impedance spectroscopic (EIS) method for measurements of the changes in membrane permeability during the process of cell anoxia. Madin-Darby canine kidney (MDCK) cells were employed as the model cells and were cultured onto gelatin-modified glassy carbon (GC) electrodes. EIS measurements were conducted at the MDCK/gelatin-modified GC electrodes with Fe(CN)(6)(3-/4-) as the redox probe. The anoxia of the cells grown onto electrode surface was induced by the addition of carbonycyanide p-(trifluoromethoxy) phenylhydrazone (FCCP) into the cell culture, in which the MDCK/gelatin-modified GC electrodes were immersed for different times. The EIS results show that the presence of FCCP in the cell culture clearly decreases the charge-transfer resistance of the Fe(CN)(6)(3-/4-) redox probe at the MDCK/gelatin-modified GC electrodes, and the charge-transfer resistance decreases with increasing time employed for immersing the MDCK/gelatin-modified GC electrodes into the cell culture containing FCCP. These results demonstrate that the EIS method could be used to monitor the changes in the cell membrane permeability during the FCCP-induced cell anoxia. To simulate the EIS system, a rational equivalent circuit was proposed and the values of ohmic resistance of the electrolyte, charge-transfer resistance and constant phase elements for both the gelatin and the cell layers are given with the fitting error in an acceptable value. This study actually offers a new and simple approach to measuring the dynamic process of cell death induced by anoxia through monitoring the changes in the cell membrane permeability.

  14. Determination of electron transfer kinetic parameters by fourier transform electrochemical impedance spectroscopic analysis.

    PubMed

    Chang, Byoung-Yong; Hong, Sung-Young; Yoo, Jung-Suk; Park, Su-Moon

    2006-10-05

    A new attempt to obtain electron transfer kinetic parameters at an electrified electrode/electrolyte interface using Fourier transform electrochemical impedance spectroscopic (FTEIS) analyses of small potential step chronoamperometric currents is presented. The kinetic parameters thus obtained allowed mass transport free voltammograms to be constructed in an overpotential region, where the diffusion limits the electron transfer reaction, using the Butler-Volmer (B-V) relation. The B-V voltammograms clearly distinguish electrode reactions that are not much different in their electron transfer kinetic parameters, thus showing very similar normal linear sweep voltammetric (SCV) behaviors. Electrochemical reduction of p-benzoquinone, which displays nearly the same SCV responses at a gold electrode regardless whether the electrode is covered by a thiolated beta-cyclodextrin self-assembled monolayer, was taken as an example for the demonstration. The results show that the two voltametrically similar systems display very different electron transfer characteristics.

  15. Study of complex impedance spectroscopic properties of Na{sub 2}Pb{sub 2}Pr{sub 2}W{sub 2}Ti{sub 4}Nb{sub 4}O{sub 30} Ceramic

    SciTech Connect

    Biswal, L.; Das, Piyush R.; Behera, Banarji

    2012-07-23

    The polycrystalline sample of Na{sub 2}Pb{sub 2}Pr{sub 2}W{sub 2}Ti{sub 4}Nb{sub 4}O{sub 30} was prepared by high temperature solid state reaction technique. The formation of compounds with an orthorhombic structure was confirmed by X-ray diffraction technique. Surface morphology study showed homogenous distribution of plate and rod like grains over the entire surface with less porosity. The study of effect of temperature on impedance parameters in the frequency range 10{sup 2}-10{sup 6} Hz and temperature range 30-500 Degree-Sign C revealed the presence of both bulk and grain boundary effects above 275 Degree-Sign C. The bulk resistance of the material decreased with rise in temperature exhibiting a typical negative temperature coefficient of resistance (NTCR) behavior like a semiconductor. Both the complex impedance and modulus studies suggested the presence of non-Debye type of relaxation in the materials. The ac conductivity spectrum obeys Johnsche's universal power law.

  16. Spectroscopic Studies of Melanin.

    DTIC Science & Technology

    1986-01-01

    il), and leading to the production of oxygen radicals (12). Gallas (13) and Kozikowski et al. (14) have studied melanin fluorescence. As part of a...Raman scattering unobservable in aqueous solution by continuous wave techniques. As was also observed by Kozikowski et al. (14), the intrinsic...168B. 14. Kozikowski SD, Wolfram LJ, Alfano RR. Fluorescence spectroscopy of eumelanins. IEEE J Quant Electron 1984;OE20:1379-1382. 15. Slawinski J

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. Dielectric relaxation and electrical conduction mechanism in A2HoSbO6 (A=Ba, Sr, Ca) Double Perovskite Ceramics: An impedance spectroscopic analysis

    NASA Astrophysics Data System (ADS)

    Halder, Saswata; Dutta, Alo; Sinha, T. P.

    2017-03-01

    The AC electrical properties of polycrystalline double perovskite oxides A2HoSbO6 (A=Ba, Sr, Ca; AHS) synthesized by solid state reaction technique has been explored by using impedance spectroscopic studies. The Rietveld refinement of the room temperature X-ray diffraction data show that Ba2HoSbO6 (BHS) has cubic phase and Sr2HoSbO6 (SHS) and Ca2HoSbO6 (CHS) crystallize in monoclinic phase. The samples show significant frequency dispersion in their dielectric properties. The polydispersive nature of the relaxation mechanism is explained by the modified Cole-Cole model. The scaling behavior of dielectric loss indicate the temperature independence of the relaxation mechanism. The magnitude of the activation energy indicates that the hopping mechanism is responsible for carrier transport in AHS. The frequency dependent conductivity spectra follow the double power law. Impedance spectroscopic data presented in the Nyquist plot (Z" versus Z‧) are used to identify an equivalent circuit along with to know the grain, grain boundary and interface contributions. The constant phase element (CPE) is used to analyze the experimental response of BHS, SHS and CHS comprehending the contribution of different microstructural features to the conduction process. The temperature dependent electrical conductivity shows a semiconducting behavior.

  2. Impedance study for the PEP-II B-factory

    SciTech Connect

    Heifets, S.; Daly, C.E.; Ko, K.

    1995-06-01

    The paper summarizes results of the impedance studies of the components of the B-factory. The prime goal of this activity was to support the design of the vacuum chamber and, at the same time, to get a reasonable model of the machine impedance, which can be used later for detail studies of collective effects.

  3. Impedance spectroscopic analysis of lead iodide perovskite-sensitized solid-state solar cells.

    PubMed

    Dualeh, Amalie; Moehl, Thomas; Tétreault, Nicolas; Teuscher, Joël; Gao, Peng; Nazeeruddin, Mohammad Khaja; Grätzel, Michael

    2014-01-28

    Mesoscopic solid-state solar cells based on the inorganic-organic hybrid perovskite CH3NH3PbI3 in conjunction with the amorphous organic semiconductor spiro-MeOTAD as a hole transport material (HTM) are investigated using impedance spectroscopy (IS). A model to interpret the frequency response of these devices is established by expanding and elaborating on the existing models used for the liquid and solid-state dye-sensitized solar cells. Furthermore, the influence of changing the additive concentrations of tert-butylpyridine and LiTFSI in the HTM and varying the HTM overlayer thickness on top of the sub-micrometer thick TiO2 on the extracted IS parameters is investigated. The internal electrical processes of such devices are studied and correlated with the overall device performance. In particular, the features in the IS responses that are attributed to the ionic and electronic transport properties of the perovskite material and manifest as a slow response at low frequency and an additional RC element at intermediate frequency, respectively, are explored.

  4. Study of the Electrical Impedance Scanning

    DTIC Science & Technology

    2007-11-02

    exhibit conductive changes that cause an impedance variation between cancerous ant health tissues. Since there are very few commercial devices...contribute somehow in the evaluation of the parameters involved. Keywords – Electrical Transimpedance Scanning, Breast cancer I. INTRODUCTION The...Electrical Transimpedance Scanning (ETS) is a new technique, non-invasive, non-irradiant, used in the diagnosis of breast cancer . Combined with other

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Synthesis, dielectric behavior and impedance measurement studies of Cr-substituted Zn-Mn ferrites

    SciTech Connect

    Hankare, P.P.; Patil, R.P.; Garadkar, K.M.; Sasikala, R.; Chougule, B.K.

    2011-03-15

    Graphical abstract: Variation of dielectric constant with frequency. Research highlights: {yields} Sol-gel route synthesized spherical crystalline nanoparticles of ZnMn{sub 1-x}Cr{sub x}FeO{sub 4}. {yields} XRD, DTA, FTIR, SEM, dielectric and impedance study. {yields} The ferrites show concentration dependence of ac electrical conductivity. {yields} Impedance response is dominated by grain boundary behavior. -- Abstract: Nanocrystalline ZnMn{sub 1-x}Cr{sub x}FeO{sub 4} (1.0 {>=} x {>=} 0) ferrites were synthesized by sol-gel technique. X-ray diffraction (XRD) confirmed the formation of single phasic cubic spinel lattice for all the compositions studied. Lattice parameter shows a decreasing trend with an increase in Cr content in the compositions. Formation of spherical nanoparticles was revealed by scanning electron microscopy (SEM) analysis. Infrared spectroscopic studies revealed two main absorption bands in the range 400-800 cm{sup -1} arising due to tetrahedral (A) and octahedral (B) site vibrations. Dielectric constant, dielectric loss tangent, ac conductivity and complex impedance were measured as a function of frequency in the range 20 Hz to 1 MHz. Frequency dependence of dielectric constant shows dielectric dispersion due to the Maxwell-Wagner type of interfacial polarization. The role of chromium in modifying structural and dielectric properties of these ferrites has been explained.

  12. 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.

  13. Study of Influence of Electrode Geometry on Impedance Spectroscopy

    SciTech Connect

    Ahmed, Riaz; Reifsnider, Kenneth L

    2011-01-01

    Electrochemical Impedance Spectroscopy (EIS) is a powerful and proven tool for analyzing AC impedance response. A conventional three electrode EIS method was used to perform the investigation in the present study. Saturated potassium chloride solution was used as the electrolyte and three different material rods were used as working electrodes. Different configurations of electrode area were exposed to the electrolyte as an active area to investigate electrode geometry effects. Counter to working electrode distance was also altered while keeping the working electrode effective area constant to explore the AC response dependence on the variation of ion travel distance. Some controlled experiments were done to validate the experimental setup and to provide a control condition for comparison with experimental results. A frequency range of 100 mHz to 1 MHz was used for all experiments. In our analysis, we have found a noteworthy influence of electrode geometry on AC impedance response. For all electrodes, impedance decreases with the increase of effective area of the electrolyte. High frequency impedance is not as dependent on geometry as low frequency response. The observed phase shift angle drops in the high frequency region with increased working electrode area, whereas at low frequency the reverse is true. Resistance and capacitive reactance both decrease with an increase of area, but resistance response is more pronounce than reactance. For lower frequencies, small changes in working area produce very distinctive EIS variations. Electrode material as well as geometry was systematically varied in the present study. From these and other studies, we hope to develop a fundamental foundation for understanding specific changes in local geometry in fuel cell (and other) electrodes as a method of designing local morphology for specific performance.

  14. 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.

  15. 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).

  16. 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.

  17. 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.

  18. 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.

  19. Spectroscopic studies of individual plasmon resonant nanoparticles

    NASA Astrophysics Data System (ADS)

    Mock, Jack J.; Smith, David R.; Barbic, Mladen; Oldenburg, Steven J.; Schultz, David A.; Schultz, Sheldon

    2003-11-01

    We present a detailed description of the apparatus and techniques that we have utilized in our experimental study of individual plas on resonant nanoparticles,along with a brief description of some major results. The apparatus consists of a spectroscopic system combined with a modified darkfield microscope, which enables the user to sequentially select individual resonant nanostructures in the microscopic field of view for spectroscopic study. Plasmon resonant nanostructures scatter light elastically,and typically have very large scattering cross-sections at their resonant optical wavelengths. In general, spectra can be obtained with acquisition times between .1 to 30 seconds,and color images can be captured using consumer digital color cameras. Spheres,tetrahedrons,and pentagonal platelets were fabricated using colloidal chemistry techniques. To produce highly anisotropic structures such as nanorods and "barbells", templates were used. Many of these nanostructures have been individually spectroscopically characterized,and their spectra correlated with their shape and size as determined by transmission electron icroscope (TEM). The unique shape,size, composition,and dielectric surroundings of the individual plasmon resonant nanostructures determine their plasmon resonant behavior. We will show how the composition of the substrate on which the particles are immobilized and the dielectric of the surrounding medium have a significant effect on the plasmon resonance of the individual particles.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Interdependence of initial cell density, drug concentration and exposure time revealed by real-time impedance spectroscopic cytotoxicity assay.

    PubMed

    Caviglia, C; Zór, K; Canepa, S; Carminati, M; Larsen, L B; Raiteri, R; Andresen, T L; Heiskanen, A; Emnéus, J

    2015-05-21

    We investigated the combined effect of the initial cell density (12,500, 35,000, 75,000, and 100,000 cells cm(-2)) and concentration of the anti-cancer drug doxorubicin on HeLa cells by performing time-dependent cytotoxicity assays using real-time electrochemical impedance spectroscopy. A correlation between the rate of cell death and the initial cell seeding density was found at 2.5 μM doxorubicin concentration, whereas this was not observed at 5 or 100 μM. By sensing the changes in the cell-substrate interaction using impedance spectroscopy under static conditions, the onset of cytotoxicity was observed 5 h earlier than when using a standard colorimetric end-point assay (MTS) which measures changes in the mitochondrial metabolism. Furthermore, with the MTS assay no cytotoxicity was observed after 15 h of incubation with 2.5 μM doxorubicin, whereas the impedance showed at this time point cell viability that was below 25%. These results indicate that impedance detection reveals cytotoxic events undetectable when using the MTS assay, highlighting the importance of combining impedance detection with traditional drug toxicity assays towards a more in depth understanding of the effect of anti-cancer drugs on in vitro assays. Moreover, the detection of doxorubicin induced toxicity determined with impedance under static conditions proved to be 6 times faster than in perfusion culture.

  5. 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.

  6. 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.

  7. An AC impedance study of steel in concrete

    NASA Astrophysics Data System (ADS)

    Lay, P.; Lawrence, P. F.; Wilkins, N. J. M.; Williams, D. E.

    1984-01-01

    Impedance measurements executed between both steel and platinum electrodes embedded in both porous and non-porous concretes were used to explore the physical characteristics of the system. A simple method is described for measuring high impedances (up to 500 M) in which the unknown impedance is compared with the imput impedance of the measuring instrument, previously calibrated. Impedance measurements on concrete immersed in an electrolyte were used to quantify concrete quality, and the dynamics of wetting, drying and electrolyte exchange were explored: the dynamics of such processes are considered to be among the factors determining the rate of corrosion of steel reinforcement under some conditions, since intermittent wetting is an efficient method for transporting oxygen and salt into the concrete. The existence of cracks along the electrode-concrete interface was inferred. Impedance changes consequent on the initiation of corrosion of steel electrodes were noted, but the changes were small and not clear-cut.

  8. 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

  9. 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.

  10. Preparation of cesium targets for gamma-spectroscopic studies

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, S.; Basu, S. K.; Chanda, S.; Deb, P.; Eqbal, Md; Kundu, S.; Joseph, D.

    2000-11-01

    A procedure to prepare monoisotopic cesium compound targets for gamma-spectroscopic experiments is described. Using this procedure, uniform targets up to thicknesses of 0.6-1.2 mg/cm 2 were prepared and used for in-beam spectroscopic studies. The purity of the target was tested by energy dispersive X-ray fluorescence (EDXRF) measurements.

  11. Spectroscopic studies of detonating heterogeneous explosives. [HNS

    SciTech Connect

    Renlund, A.M.; Trott, W.M.

    1985-01-01

    The experimental objectives of this work are to use real-time spectroscopic techniques, emission spectroscopy and Raman spectra to monitor chemical and physical changes in shock-loaded or detonating high explosive (HE) samples. The investigators hope to identify chemical species including any transient intermediates. Also, they wish to determine the physical state of the material when the reactions are taking place; measure the temperature and the pressure; and study the effect of different initiation parameters and bulk properties of the explosive material. This work is just part of the effort undertaken to gain information on the detailed chemistry involved in initiation and detonation. In summary, the investigators have obtained vibrational temperatures of some small radical products of detonation, which may correlate with the detonation temperature. They have also observed that NO/sub 2/ is an early product from detonating HNS and RDX, and that other electronically excited radical species such as CN(B) are formed in HNS detonations. In the Raman work, the single-pulse spectra could be obtained even in the severe environment of a detonation, and that the rate of removal of the parent molecule could be monitored. 2 refs., 6 figs.

  12. Study of impedance spectra for dry and wet EarEEG electrodes.

    PubMed

    Kappel, Simon L; Kidmose, Preben

    2015-01-01

    EarEEG is a novel recordings concept where electrodes are embedded on the surface of an earpiece customized to the individual anatomical shape of the users ear. A key parameter for recording EEG signals of good quality is a stable and low impedance electrode-body interface. This study characterizes the impedance for dry and wet EarEEG electrodes in a study of 10 subjects. A custom made and automated setup was used to characterize the impedance spectrum from 0.1 Hz-2 kHz. The study of dry electrodes showed a mean (standard deviation) low frequency impedance of the canal electrodes of 1.2 MΩ (1.4 MΩ) and the high frequency impedance was 230 kΩ (220 kΩ). For wet electrodes the low frequency impedance was 34 kΩ (37 kΩ) and the high frequency impedance was 5.1 kΩ (4.4 kΩ). The high standard deviation of the impedance for dry electrodes imposes very high requirements for the input impedance of the amplifier in order to achieve an acceptable common-mode rejection. The wet electrode impedance was in line with what is typical for a wet electrode interface.

  13. Estimation of postmortem interval using an electric impedance spectroscopy technique: a preliminary study.

    PubMed

    Mao, Shiwei; Dong, Xiuzhen; Fu, Feng; Seese, Ronald R; Wang, Zhenyuan

    2011-09-01

    The objective of this study was to develop a rapid method for the estimation of postmortem interval (PMI) using electric impedance spectroscopy. Postmortem rat spleens were studied at 10°C, 20°C, and 30°C; The results obtained demonstrated that postmortem interval negatively correlated with the absolute value of Im Z(//) (capacitive reactance component) in electrical impedance. This suggests that electric impedance spectroscopy may be a sensitive tool to determine the postmortem interval.

  14. Spectroscopic studies of microwave plasmas containing hexamethyldisiloxane

    NASA Astrophysics Data System (ADS)

    Nave, A. S. C.; Mitschker, F.; Awakowicz, P.; Röpcke, J.

    2016-10-01

    Low-pressure microwave discharges containing hexamethyldisiloxane (HMDSO) with admixtures of oxygen and nitrogen, used for the deposition of silicon containing films, have been studied spectroscopically. Optical emission spectroscopy (OES) in the visible spectral range has been combined with infrared laser absorption spectroscopy (IRLAS). The experiments were carried out in order to analyze the dependence of plasma chemical phenomena on power and gas mixture at relatively low pressures, up to 50 Pa, and power values, up to 2 kW. The evolution of the concentration of the methyl radical, CH3, and of seven stable molecules, HMDSO, CH4, C2H2, C2H4, C2H6, CO and CO2, was monitored in the plasma processes by in situ IRLAS using tunable lead salt diode lasers (TDL) and external-cavity quantum cascade lasers (EC-QCL) as radiation sources. To achieve reliable values for the gas temperature inside and outside the plasma bulk as well as for the temperature in the plasma hot and colder zones, which are of great importance for calculation of species concentrations, three different methods based on emission and absorption spectroscopy data of N2, CH3 and CO have been used. In this approach line profile analysis has been combined with spectral simulation methods. The concentrations of the various species, which were found to be in the range between 1011 to 1015 cm-3, are in the focus of interest. The influence of the discharge parameters power, pressure and gas mixture on the molecular concentrations has been studied. To achieve further insight into general plasma chemical aspects the dissociation of the HMDSO precursor gas including its fragmentation and conversion to the reaction products was analyzed in detail.

  15. Optical and impedance studies of pure and Ba-doped ZnS quantum dots

    NASA Astrophysics Data System (ADS)

    Firdous, Arfat; Baba, M. Aslam; Singh, D.; Bhat, Abdul Hamid

    2015-02-01

    Chemical precipitation method using a high-boiling solvent is used to synthesize ZnS and Ba-doped ZnS quantum dots. The presence of organic ligands in the prepared nanostructures is verified using Fourier transform infra-red spectroscopic studies. The samples have been analysed using X-ray diffraction analysis confirming nanocrystallinity of the as-prepared quantum dots (QD). The mean crystal size obtained by full width half maxima analysis is 3.2 nm for ZnS and 3.9, 4.2 nm for ZnS:Ba (2, 4 mM). TEM micrographs also reveal nanosized particles of ZnS and Ba-doped ZnS. An optical absorption study conducted in UV-Vis range 150-600 nm reveals the transparency of these quantum dots in entire visible range but not in ultraviolet range. The results based on optical analysis yield band gap values as 4.88 eV for ZnS and 4.69, 4.43 eV for ZnS:Ba (2, 4 mM) quantum dots. Impedance analysis of the samples was carried out to reveal the variation of impedance with frequency at room temperature. These results show the capacitive admittance associated with the quantum dots and hence nanostructure ZnS and Ba-doped ZnS can have potential applications in electronics as nano-tuned devices in which resonant frequency can be adjusted by controlling the size and shape of the quantum dots.

  16. 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

  17. 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.

  18. [Experimental study on electrical impedance properties of human hepatoma cells].

    PubMed

    Fang, Yun; Tang, Zhiyuan; Zhang, Qian; Zhao, Xin; Ma, Qing

    2014-10-01

    The AC impedance of human hepatoma SMMC-7721 cells were measured in our laboratory by Agilent 4294A impedance analyzer in the frequency range of 0.01-100 MHz. And then the effect of hematocrit on electrical impedance characteristics of hepatoma cells was observed by electrical impedance spectroscopy, Bode diagram, Nyquist diagram and Nichols diagram. The results showed that firstly, there is a frequency dependence, i.e., the increment of real part and the imaginary part of complex electrical impedance (δZ', δZ"), the increment of the amplitude modulus of complex electrical impedance (δ[Z *]) and phase angle (δθ) were all changed with the increasing frequency. Secondly, it showed cell volume fraction (CVF) dependence, i. e. , the increment of low-frequency limit (δZ'0, δ[Z*] 0), peak (δZ"(p), δθ(p)), area and radius (Nyquist diagram, Nichols diagram) were all increased along with the electric field frequency. Thirdly, there was the presence of two characteristic frequencies: the first characteristic frequency (f(c1)) and the second characteristic frequency (f(c2)), which were originated respectively in the polarization effects of two interfaces that the cell membrane and extracellular fluid, cell membrane and cytoplasm. A conclusion can be drawn that the electrical impedance spectroscopy is able to be used to observe the electrical characteristics of human hepatoma cells, and therefore this method can be used to investigate the electrophysiological mechanisms of liver cancer cells, and provide research tools and observation parameters, and it also has important theoretical value and potential applications for screening anticancer drugs.

  19. Hygroscopic particle behavior studied by interdigitated array microelectrode impedance sensors.

    PubMed

    Schindelholz, Eric; Tsui, Lok-kun; Kelly, Robert G

    2014-01-09

    The hygroscopic behavior of soluble salts bears importance in many research fields including atmospheric sciences, corrosion, porous building materials, and pharmaceuticals. Several methods have been used to study deliquescence (solid to liquid) and efflorescence (liquid to solid) phase transitions of these salts. In this study, we measured the deliquescence and efflorescence RH values of single salt microparticles deposited on an interdigitated microelectrode sensor via electrical impedance. The salts examined were NaCl, LiCl, NaBr, KCl, and MgCl2. Measured values were in agreement with in situ optical microscopic observations and, with the exception of MgCl2, literature values. In the case of MgCl2, deliquescence occurred at 33% RH and 12-15% RH, with the latter range being previously unreported. The depressed deliquescence RH was hypothesized to be a result of the formation of a metastable MgCl2 hydrate. Incomplete efflorescence of MgCl2 was also observed after exposure to <1.5% RH for up to 22 h due to formation of solid shells which trapped fluid. The phenomena elucidated by these results provide an explanation for the anomalous water retention and uptake behavior of MgCl2 below 33% RH reported elsewhere in the literature. The results presented in this study validate the use of this method as an alternative or complementary method for study of bulk-phase transitions of substrate-deposited particles across a broad RH range. These findings also demonstrate the utility of this method for detection of fluid trapping which cannot be directly ascertained by gravimetric and line-of-sight techniques commonly used in the study of hygroscopic particles.

  20. 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.

  1. [Input impedance for studying hydraulic parameters of the vessel system].

    PubMed

    Naumov, A Iu; Sheptutsolov, K V; Balashov, S A; Mel'kumiants, A M

    2001-03-01

    Vascular input impedance can be used as an effective tool in estimating hydraulic parameters of arterial bed. These parameters may be interpreted as hydraulic resistance, elastance and inertance of particular sites of the arterial system. There is no significant difference between these parameters and those obtained through a direct measurement.

  2. Highly sensitive electrochemical impedance spectroscopic detection of DNA hybridization based on Au(nano)-CNT/PAN(nano) films.

    PubMed

    Zhou, Na; Yang, Tao; Jiang, Chen; Du, Meng; Jiao, Kui

    2009-01-15

    A polyaniline nanofibers (PAN(nano))/carbon paste electrode (CPE) was prepared via dopping PAN(nano) in the carbon paste. The nanogold (Au(nano)) and carbon nanotubes (CNT) composite nanoparticles were bound on the surface of the PAN(nano)/CPE. The immobilization and hybridization of the DNA probe on the Au(nano)-CNT/PAN(nano) films were investigated with differential pulse voltammetry (DPV) and cyclic voltammetry (CV) using methylene blue (MB) as indicator, and electrochemical impedance spectroscopy (EIS) using [Fe(CN)(6)](3-/4-) as redox probe. The voltammetric peak currents of MB increased dramatically owing to the immobilization of the probe DNA on the Au(nano)-CNT/PAN(nano) films, and then decreased obviously owing to the hybridization of the DNA probe with the complementary single-stranded DNA (cDNA). The electron transfer resistance (R(et)) of the electrode surface increased after the immobilization of the probe DNA on the Au(nano)-CNT/PAN(nano) films and rose further after the hybridization of the probe DNA. The remarkable difference between the R(et) value at the DNA-immobilized electrode and that at the hybridized electrode could be used for the label-free EIS detection of the target DNA. The loading of the DNA probe on Au(nano)-CNT/PAN(nano) films was greatly enhanced and the sensitivity for the target DNA detection was markedly improved. The sequence-specific DNA of phosphinothricin acetyltransferase (PAT) gene and the polymerase chain reaction (PCR) amplification of nopaline synthase (NOS) gene from transgenically modified beans were determined with this label-free EIS DNA detection method. The dynamic range for detecting the PAT gene sequence was from 1.0 x 10(-12)mol/L to 1.0 x 10(-6)mol/L with a detection limit of 5.6 x 10(-13)mol/L.

  3. Local impedance spectroscopic and microstructural analyses of Al-in-diffused Li7La3Zr2O12

    NASA Astrophysics Data System (ADS)

    Ahn, Jee Hyun; Park, Seung-Young; Lee, Jae-Myung; Park, Youngsin; Lee, Jong-Heun

    2014-05-01

    A cylindrical Li7La3Zr2O12 specimen in contact with an Al2O3 crucible is sintered and the effect of Al diffusion on the microstructure, phase composition, and Li-ion conductivity of Li7La3Zr2O12 is investigated. The decrease in the Li-ion conductivity and Al concentration with increasing distance from the contact area with the Al2O3 crucible is confirmed using spatially resolved local-impedance spectroscopy and compositional analysis. The region close to the Al2O3 crucible shows abnormally large grains (size > 0.7 mm) within a matrix of fine grains (size: ∼10 μm), abundant intergranular liquid, the Li7La3Zr2O12 phase mostly in cubic form, and a high Li-ion conductivity (8.5 × 10-5 S cm-1). In contrast, the region far from the Al2O3 crucible exhibits uniform fine grains (size: ∼10 μm), scarce intergranular liquid, the tetragonal form of the Li7La3Zr2O12 phase, and a low Li-ion conductivity (1.1 × 10-6 S cm-1). The incorporation of Al into the Li7La3Zr2O12 lattice and the resulting increase in the number of Li-ion vacancies is suggested to be the main reason for the increase in the Li-ion conductivity. The origins of the abnormal grain growth induced by the diffusion of Al are discussed in relation to the atomic surface structures of Li7La3Zr2O12 and the presence of intergranular liquid phase.

  4. Studies on Electrical behavior of Glucose using Impedance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Juansah, Jajang; Yulianti, Wina

    2016-01-01

    In this work we report the electrical characteristics of glucose at different frequencies. We show the correlation between electrical properties (impedance, reactance, resistance and conductance) of glucose and glucose concentration. Electrical property measurements on glucose solution were performed in order to formulate the correlation. The measurements were conducted for frequencies between 50 Hz and 1 MHz. From the measurements, we developed a single-pole Cole-Cole graph as a function of glucose concentration.

  5. 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.

  6. Spectroscopic Studies of Double Beta Decays and MOON

    NASA Astrophysics Data System (ADS)

    Ejiri, H.

    2007-10-01

    This is a brief review of future spectroscopic experiments of neutrino-less double beta decays (0νββ) and the MOON (Mo Observatory Of Neutrinos) project. Spectroscopic 0νββ experiments of MOON, SuperNEMO and DCBA are planned to study Majorana masses in the quasi-degenerate (QD) and inverted mass hierarchy (IH) regions. MOON aims at 0νββ studies with the ν-mass sensitivities of 100-30 meV by means of a super ensemble of multi-layer modules, each being consist of a scintillator plate, two tracking detector planes and a thin ββ source film.

  7. 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.

  8. Studies of an Adaptive Kaczmarz Method for Electrical Impedance Imaging

    NASA Astrophysics Data System (ADS)

    Li, Taoran; Isaacson, David; Newell, Jonathan C.; Saulnier, Gary J.

    2013-04-01

    We present an adaptive Kaczmarz method for solving the inverse problem in electrical impedance tomography and determining the conductivity distribution inside an object from electrical measurements made on the surface. To best characterize an unknown conductivity distribution and avoid inverting the Jacobian-related term JTJ which could be expensive in terms of memory storage in large scale problems, we propose to solve the inverse problem by adaptively updating both the optimal current pattern with improved distinguishability and the conductivity estimate at each iteration. With a novel subset scheme, the memory-efficient reconstruction algorithm which appropriately combines the optimal current pattern generation and the Kaczmarz method can produce accurate and stable solutions adaptively compared to traditional Kaczmarz and Gauss-Newton type methods. Several reconstruction image metrics are used to quantitatively evaluate the performance of the simulation results.

  9. On-line separator for {gamma}-spectroscopic studies

    SciTech Connect

    Popeko, A. G.; Belozerov, A. V.; Chepigin, V. I.; Kabachenko, A. P.; Malyshev, O. N.; Shutov, A. V.; Svirikhin, A. I.; Yeremin, A. V.; Dorvaux, O.; Hauschild, K.; Korichi, A.; Lopez-Martens, A.

    2008-05-12

    We report about R and D of the new separator for spectroscopic studies which we plan to install at the beam of the modernized U400R FLNR cyclotron and which will allow to realize new possibilities of the JINR-IN2P3 collaboration project GABRIELA.

  10. On-line separator for γ-spectroscopic studies

    NASA Astrophysics Data System (ADS)

    Popeko, A. G.; Belozerov, A. V.; Chepigin, V. I.; Dorvaux, O.; Hauschild, K.; Kabachenko, A. P.; Korichi, A.; Lopez-Martens, A.; Malyshev, O. N.; Shutov, A. V.; Svirikhin, A. I.; Yeremin, A. V.

    2008-05-01

    We report about R&D of the new separator for spectroscopic studies which we plan to install at the beam of the modernized U400R FLNR cyclotron and which will allow to realize new possibilities of the JINR-IN2P3 collaboration project GABRIELA [1, 2].

  11. High temperature furnace system for vacuum ultraviolet spectroscopic studies.

    PubMed

    Brown, C M; Naber, R H; Tilford, S G; Ginter, M L

    1973-08-01

    An improved furnace system for use in vacuum ultraviolet spectroscopic studies of atomic and molecular species stable at high temperatures (800-2500 degrees C) is described in detail. A new and improved high resolution spectrum of Mg I and several impurity spectra produced in the furnace are presented.

  12. 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

  13. 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

  14. 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.

  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. Integrated Spectroscopic Studies of Hydrous Sulfate Minerals

    NASA Technical Reports Server (NTRS)

    Dyar, M. D.; Lane, M. D.; Bishop, J. L.; OConnor, V.; Cloutis, E.; Hiroi, T.

    2005-01-01

    Sulfate minerals have been identified in Martian meteorites and on Mars using a suite of instruments aboard the MER rovers. These results have confirmed previous groundbased observations and orbital measurements that suggested their presence. The orbiting OMEGA instrument on Mars Express is also finding evidence for sulfate. In order to better interpret remote-sensing data, we present here the results of a coordinated visible/near infrared (VNIR) reflectance, Moussbauer (MB), and thermal emittance study of wellcharacterized hydrous sulfate minerals.

  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. 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.

  19. 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.

  20. 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.

  1. Spectroscopic studies of silver boro tellurite glasses

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    The FTIR absorption and Raman scattering studies were used to obtain the structural information of AgI-Ag2O-[(1-x)B2O3-xTeO2] (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 TeO2 on SBT glass system is that as increasing the concentration of TeO2 the band intensity at 707 cm-1 increase.

  2. 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

  3. Spectroscopic studies near the proton drip line

    SciTech Connect

    Toth, K.S. ); Moltz, D.M.; Nitschke, J.M.; Wilmarth, P.A. ); Robertson, J.D. )

    1990-01-01

    We have investigated nuclei close to the proton drip line by using heavy-ion fusion reactions to produce extremely neutron-deficient nuclides. Their nuclear decay properties were studied by using on-line isotope separators at Oak Ridge (UNISOR) and Berkeley (OASIS), the Oak Ridge National Laboratory velocity filter, and a fast helium-gas-jet transport system at Lawrence Berkeley Laboratory 88-Inch Cyclotron. Many isotopes, isomers, and {beta}-delayed-proton and {alpha}-particle emitters were discovered. This contribution summarizes three topics that are part of our overall program: decay rates of even-even {alpha}-particle emitters, mass excesses of {sup 181}Pb, {sup 182}Pb, and {sup 183}Pb, and {beta}-delayed proton emitters near N = 82. 14 refs., 6 figs.

  4. 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.

  5. Interactions of Isophorone Derivatives with DNA: Spectroscopic Studies

    PubMed Central

    Deiana, Marco; Matczyszyn, Katarzyna; Massin, Julien; Olesiak-Banska, Joanna; Andraud, Chantal; Samoc, Marek

    2015-01-01

    Interactions of three new isophorone derivatives, Isoa Isob and Isoc with salmon testes DNA have been investigated using UV-Vis, fluorescence and circular dichroism spectroscopic methods. All the studied compounds interact with DNA through intercalative binding mode. The stoichiometry of the isophorone/DNA adducts was found to be 1:1. The fluorescence quenching data revealed a binding interaction with the base pairs of DNA. The CD data indicate that all the investigated isophorones induce DNA modifications. PMID:26069963

  6. Spectroscopic Studies of Nearby Cool Stars: The DUNES Sample

    NASA Astrophysics Data System (ADS)

    Maldonado, J.; Martínez-Arnáiz, R. M.; Eiroa, C.; Montes, D.

    2009-02-01

    At the Universities of Madrid we are carrying out a systematic analysis of the spectroscopic properties of the nearby (d<25 pc), late-type stellar population with the aim of contributing to the knowledge of the stellar formation history in the solar neighbourhood. Part of our sample will be observed by DUNES, a Herschel OTKP aiming at detecting and studying cold, faint dust disks around nearby stars. In this contribution we present some preliminary results of the kinematics of the DUNES sample.

  7. Spectroscopic Studies of Nearby Cool Stars: The DUNES Sample

    NASA Astrophysics Data System (ADS)

    Maldonado, J.; Martinez-Arnáiz, R. M.; Eiroa, C.; Montes, D.

    At the universities of Madrid we are carrying out a systematic analysis of the spectroscopic properties of the nearby (d<25pc), late-type stellar population with the aim of contributing to the knowledge of the stellar formation history in the solar neighbourhood. Part of our sample will be observed by DUNES, a Herschel OTKP aiming at detecting and studying cold, faint dust disks around nearby stars. In this contribution we present some preliminary results on the kinematics of the DUNES sample.

  8. Photoelectron spectroscopic studies of 5-halouracil anions

    SciTech Connect

    Radisic, Dunja; Ko, Yeon Jae; Nilles, John M.; Stokes, Sarah T.; Bowen, Kit H.; Sevilla, Michael D.; Rak, Janusz

    2011-01-07

    The parent negative ions of 5-chlorouracil, UCl{sup -} and 5-fluorouracil, UF{sup -} have been studied using anion photoelectron spectroscopy in order to investigate the electrophilic properties of their corresponding neutral halouracils. The vertical detachment energies (VDE) of these anions and the adiabatic electron affinities (EA) of their neutral molecular counterparts are reported. These results are in good agreement with the results of previously published theoretical calculations. The VDE values for both UCl{sup -} and UF{sup -} and the EA values for their neutral molecular counterparts are much greater than the corresponding values for both anionic and neutral forms of canonical uracil and thymine. These results are consistent with the observation that DNA is more sensitive to radiation damage when thymine is replaced by halouracil. While we also attempted to prepare the parent anion of 5-bromouracil, UBr{sup -}, we did not observe it, the mass spectrum exhibiting only Br{sup -} fragments, i.e., 5-bromouracil apparently underwent dissociative electron attachment. This observation is consistent with a previous assessment, suggesting that 5-bromouracil is the best radio-sensitizer among these three halo-nucleobases.

  9. Photoelectron spectroscopic studies of 5-halouracil anions

    NASA Astrophysics Data System (ADS)

    Radisic, Dunja; Ko, Yeon Jae; Nilles, John M.; Stokes, Sarah T.; Sevilla, Michael D.; Rak, Janusz; Bowen, Kit H.

    2011-01-01

    The parent negative ions of 5-chlorouracil, UCl- and 5-fluorouracil, UF- have been studied using anion photoelectron spectroscopy in order to investigate the electrophilic properties of their corresponding neutral halouracils. The vertical detachment energies (VDE) of these anions and the adiabatic electron affinities (EA) of their neutral molecular counterparts are reported. These results are in good agreement with the results of previously published theoretical calculations. The VDE values for both UCl- and UF- and the EA values for their neutral molecular counterparts are much greater than the corresponding values for both anionic and neutral forms of canonical uracil and thymine. These results are consistent with the observation that DNA is more sensitive to radiation damage when thymine is replaced by halouracil. While we also attempted to prepare the parent anion of 5-bromouracil, UBr-, we did not observe it, the mass spectrum exhibiting only Br- fragments, i.e., 5-bromouracil apparently underwent dissociative electron attachment. This observation is consistent with a previous assessment, suggesting that 5-bromouracil is the best radio-sensitizer among these three halo-nucleobases.

  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. Spectroscopic studies of alkaline activated slag geopolymers

    NASA Astrophysics Data System (ADS)

    Mozgawa, W.; Deja, J.

    2009-04-01

    In the work, results of structural studies of different geopolymers, obtained using a granulated blast furnace slag, are presented. The slag was subjected to an alkaline activation process. As activators, NaOH, Na 2CO 3 and liquid glass were applied. IR and NMR spectroscopy were the main experimental methods used, the results obtained were compared with XRD phase analysis and SEM observations. In the IR spectra of raw slag as well as in the spectra of products of paste hydration, the bands due to the characteristic vibrations of bonds observed in both types of oxygen bridges: Si-O-Si and Si-O-Al, were assigned. These bridges constitute basic structural units, forming tetrahedral geopolymer chains. It was found that the slag composition, mainly SiO 2/Al 2O 3 ratio and modification in oxides concentration, influences the presence of the bands connected with the phases (mainly C-S-H) formed during the hydration in the IR spectra. Additionally, significant effect of amorphous phases share on the spectra shape was established. 29Si and 27Al MAS-NMR spectra of initial slag geopolymers and pastes provided information concerning coordination of both atoms in the structures. It was revealed that the kind of slag geopolymers and the conditions of paste hydration influence connectedness of silicooxygen tetrahedra and coordination number of aluminium atoms. Based on IR spectra, it was also possible to determine the influence of the activator type, activation time and hydration conditions on the products formed. Significant changes were observed for the bands assigned to vibrations of carbonate and hydroxide groups. The changes were also noticed in the case of bands due to vibrations of silicate and aluminosilicate bonds.

  14. Analysis of different device-based intrathoracic impedance vectors for detection of heart failure events (from the Detect Fluid Early from Intrathoracic Impedance Monitoring study).

    PubMed

    Heist, E Kevin; Herre, John M; Binkley, Philip F; Van Bakel, Adrian B; Porterfield, James G; Porterfield, Linda M; Qu, Fujian; Turkel, Melanie; Pavri, Behzad B

    2014-10-15

    Detect Fluid Early from Intrathoracic Impedance Monitoring (DEFEAT-PE) is a prospective, multicenter study of multiple intrathoracic impedance vectors to detect pulmonary congestion (PC) events. Changes in intrathoracic impedance between the right ventricular (RV) coil and device can (RVcoil→Can) of implantable cardioverter-defibrillators (ICDs) and cardiac resynchronization therapy ICDs (CRT-Ds) are used clinically for the detection of PC events, but other impedance vectors and algorithms have not been studied prospectively. An initial 75-patient study was used to derive optimal impedance vectors to detect PC events, with 2 vector combinations selected for prospective analysis in DEFEAT-PE (ICD vectors: RVring→Can + RVcoil→Can, detection threshold 13 days; CRT-D vectors: left ventricular ring→Can + RVcoil→Can, detection threshold 14 days). Impedance changes were considered true positive if detected <30 days before an adjudicated PC event. One hundred sixty-two patients were enrolled (80 with ICDs and 82 with CRT-Ds), all with ≥1 previous PC event. One hundred forty-four patients provided study data, with 214 patient-years of follow-up and 139 PC events. Sensitivity for PC events of the prespecified algorithms was as follows: ICD: sensitivity 32.3%, false-positive rate 1.28 per patient-year; CRT-D: sensitivity 32.4%, false-positive rate 1.66 per patient-year. An alternative algorithm, ultimately approved by the US Food and Drug Administration (RVring→Can + RVcoil→Can, detection threshold 14 days), resulted in (for all patients) sensitivity of 21.6% and a false-positive rate of 0.9 per patient-year. The CRT-D thoracic impedance vector algorithm selected in the derivation study was not superior to the ICD algorithm RVring→Can + RVcoil→Can when studied prospectively. In conclusion, to achieve an acceptably low false-positive rate, the intrathoracic impedance algorithms studied in DEFEAT-PE resulted in low sensitivity for the prediction of heart

  15. 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.

  16. Spectroscopic studies of cold, gas-phase biomolecular ions

    NASA Astrophysics Data System (ADS)

    Rizzo, Thomas R.; Stearns, Jaime A.; Boyarkin, Oleg V.

    While the marriage of mass spectrometry and laser spectroscopy is not new, developments over the last few years in this relationship have opened up new horizons for the spectroscopic study of biological molecules. The combination of electrospray ionisation for producing large biological molecules in the gas phase together with cooled ion traps and multiple-resonance laser schemes are allowing spectroscopic investigation of individual conformations of peptides with more than a dozen amino acids. Highly resolved infrared spectra of single conformations of such species provide important benchmarks for testing the accuracy of theoretical calculations. This review presents a number of techniques employed in our laboratory and in others for measuring the spectroscopy of cold, gas-phase protonated peptides. We show examples that demonstrate the power of these techniques and evaluate their extension to still larger biological molecules.

  17. A Study of Impedance Relationships in Dual Frequency PECVD Process Plasma

    NASA Astrophysics Data System (ADS)

    Keil, Douglas; Augustyniak, Edward; Sakiyama, Yukinori; Pecvd/Ald Team

    2016-09-01

    Commercial plasma process reactors are commonly operated with a very limited suite of on-board plasma diagnostics. However, as process demands advance so has the need for detailed plasma monitoring and diagnosis. The VI probe is one of the few instruments commonly available for this task. We present a study of voltage, current, impedance and phase trends acquired by off-the-shelf VI probes in Dual Frequency (DF) 400 kHz/13.56MHz capacitively-coupled plasma (CCP) as typically used for Plasma Enhanced Chemical Vapor Deposition (PECVD). These plasmas typically operate at pressures from 1 to 5 Torr and at RF power levels of 3 W/cm2. Interpretation of DF VI probe impedance trends is challenging. Non-linear interactions are known to exist in plasma impedance scaling with low and high frequency RF power. Simple capacitive sheath models typically do not simultaneously reproduce the impedance observed at each drive frequency. This work will compare VI probe observed DF CCP impedance tends with plasma fluid simulation. Also explored is the agreement seen with sheath models presently available in the literature. Prospects for the creation of useful equivalent circuit models is also discussed.

  18. [A study of coordinates transform iterative fitting method to extract bio-impedance model parameters bio-impedance model parameters].

    PubMed

    Zhou, Liming; Yang, Yuxing; Yuan, Shiying

    2006-02-01

    A new algorithm, the coordinates transform iterative optimizing method based on the least square curve fitting model, is presented. This arithmetic is used for extracting the bio-impedance model parameters. It is superior to other methods, for example, its speed of the convergence is quicker, and its calculating precision is higher. The objective to extract the model parameters, such as Ri, Re, Cm and alpha, has been realized rapidly and accurately. With the aim at lowering the power consumption, decreasing the price and improving the price-to-performance ratio, a practical bio-impedance measure system with double CPUs has been built. It can be drawn from the preliminary results that the intracellular resistance Ri increased largely with an increase in working load during sitting, which reflects the ischemic change of lower limbs.

  19. 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

    2014-11-11

    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.

  20. Impedance study of membrane dehydration and compression in proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Le Canut, Jean-Marc; Latham, Ruth; Mérida, Walter; Harrington, David A.

    Electrochemical impedance spectroscopy (EIS) is used to measure drying and rehydration in proton exchange membrane fuel cells running under load. The hysteresis between forward and backward acquisition of polarization curves is shown to be largely due to changes in the membrane resistance. Drying tests are carried out with hydrogen and simulated reformate (hydrogen and carbon dioxide), and quasi-periodic drying and rehydration conditions are studied. The membrane hydration state is clearly linked to the high-frequency arc in the impedance spectrum, which increases in size for dry conditions indicating an increase in membrane resistance. Changes in impedance spectra as external compression is applied to the cell assembly show that EIS can separate membrane and interfacial effects, and that changes in membrane resistance dominate. Reasons for the presence of a capacitance in parallel with the membrane resistance are discussed.

  1. 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.

  2. 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.

  3. 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.

  4. Vibrational spectroscopic studies of newly developed synthetic biopolymers.

    PubMed

    Bista, Rajan K; Bruch, Reinhard F; Covington, Aaron M

    2010-05-01

    Vibrational spectroscopic techniques such as near-infrared (NIR), Fourier transform infrared (FTIR), and Raman spectroscopy are valuable diagnostic tools that can be used to elucidate comprehensive structural information of numerous biological samples. In this review article, we have highlighted the advantages of nanotechnology and biophotonics in conjunction with vibrational spectroscopic techniques in order to understand the various aspects of new kind of synthetic biopolymers termed as polyethylene glycol (PEG)ylated lipids. In contrast to conventional phospholipids, these novel lipids spontaneously form liposomes or nanovesicles upon hydration, without the supply of external activation energy. The amphiphiles considered in this study differ in their hydrophobic acyl chain length and contain different units of PEG hydrophilic headgroups. We have further explored the thermotropic phase behaviors and associated changes in the conformational order/disorder of such lipids by using variable-temperature FTIR and Raman spectroscopy. Phase transition temperature profiles and correlation between various spectral indicators have been identified by either monitoring the shifts in the vibrational peak positions or plotting vibrational peak intensity ratios in the C--H stretching region as a function of temperature. To supplement our observations of phase transformations, a thermodynamic approach known as differential scanning calorimetry (DSC) has been applied and revealed a good agreement with the infrared and Raman spectroscopic data. Finally, the investigation of thermal properties of lipids is extremely crucial for numerous purposes, thus the results obtained in this work may find application in a wide variety of studies including the development of PEGylated lipid based drug and substances delivery vehicles.

  5. Comparative study of electrolyte additives using electrochemical impedance spectroscopy on symmetric cells

    NASA Astrophysics Data System (ADS)

    Petibon, R.; Sinha, N. N.; Burns, J. C.; Aiken, C. P.; Ye, Hui; VanElzen, Collette M.; Jain, Gaurav; Trussler, S.; Dahn, J. R.

    2014-04-01

    The effect of various electrolyte additives and additive combinations added to a 1 M LiPF6 EC:EMC electrolyte on the positive and negative electrodes surface of 1 year old wound LiCoO2/graphite cells and Li[Ni0.4Mn0.4Co0.2])O2/graphite cells was studied using electrochemical impedance spectroscopy (EIS) on symmetric cells. The additives tested were: vinylene carbonate (VC), trimethoxyboroxine (TMOBX), fluoroethylene carbonate (FEC), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and H2O alone or in combination. In general, compared to control electrolyte, the additives tested reduced the impedance of the positive electrode and increased the impedance of the negative electrode with the exception of LiTFSI in Li[Ni0.4Mn0.4Co0.2]O2/graphite wound cells. Higher charge voltage led to higher positive electrode impedance, with the exception of 2%VC + 2% FEC, and 2% LiTFSI. In some cases, some additives when mixed with another controlled the formation of the SEI at one electrode, and shared the formation of the SEI at one electrode when mixed with a different additive.

  6. 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.

  7. Studying a new shape for mechanical impedance matchers in Mario Schenberg transducers

    NASA Astrophysics Data System (ADS)

    Frajuca, Carlos; da Silva Bortoli, Fabio; Simao Magalhaes, Nadja

    2006-03-01

    ``Mario Schenberg'' is a spherical resonant-mass gravitational wave (GW) detector that is expected to be part of a GW detection array of two detectors. Another one is been built in The Netherlands. Their resonant frequencies will be around 3 kHz with a bandwidth of about 200 Hz. This range of frequencies is new in a field where the typical frequencies lay below 1 kHz, making the transducer development much more complex. Some studies indicated that the use of low mass mechanical resonators (used for impedance matching to the parametric transducer, in a cold damping regime) allows the detector to reach the standard quantum limit. In this work we describe the study of a new shape for the impedance matching resonator used to obtain a better coupling between the sphere and the transducers and a better use of the space inside the experimental chamber.

  8. Study of Paclitaxel-Treated HeLa Cells by Differential Electrical Impedance Flow Cytometry

    PubMed Central

    Kirkegaard, Julie; Clausen, Casper Hyttel; Rodriguez-Trujillo, Romen; Svendsen, Winnie Edith

    2014-01-01

    This work describes the electrical investigation of paclitaxel-treated HeLa cells using a custom-made microfluidic biosensor for whole cell analysis in continuous flow. We apply the method of differential electrical impedance spectroscopy to treated HeLa cells in order to elucidate the changes in electrical properties compared with non-treated cells. We found that our microfluidic system was able to distinguish between treated and non-treated cells. Furthermore, we utilize a model for electrical impedance spectroscopy in order to perform a theoretical study to clarify our results. This study focuses on investigating the changes in the electrical properties of the cell membrane caused by the effect of paclitaxel. We observe good agreement between the model and the obtained results. This establishes the proof-of-concept for the application in cell drug therapy. PMID:25587422

  9. Spectroscopic studies of carbon impurities in PISCES-A

    SciTech Connect

    Ra, Y.; Hirooka, Y.; Leung, W.K.; Conn, R.W. . Inst. of Plasma and Fusion Research); Pospieszczyk, A. . Inst. fuer Plasmaphysik)

    1989-08-01

    The graphite used for the limiter of the tokamak reactor produces carbon-containing molecular impurities as a result of the interactions with the edge plasma. The behavior of these molecular impurities has been studied using emission spectroscopy. The present study includes: finding molecular bands and atomic lines in the visible spectral range which can be used for the study of the molecular impurities, studying the breakup processes of the molecular impurities on their way from the source into the plasma, developing a spectroscopic diagnostic method for the absolute measurement of the molecular impurity flux resulting from graphite erosion. For these studies, carbon-containing molecules such as CH{sub 4}, C{sub 2}H{sub 2}, C{sub 2}H{sub 4}, and CO{sub 2} were injected into the tokamak-boundary,like plasma generated by PISCES-A. The spectrograms of these gases were taken. Many useful bands and lines were determined from the spectrograms. The breakup processes of these gases were studied by observing the spatial profiles of the emission of the molecules and their radicals for different plasma conditions. For the absolute measurement of the eroded molecular impurity flux, the photon efficiency of the lines and bands were found by measuring the absolute number of the emitted photons and injected gas molecules. The chemical sputtering yield of graphite by hydrogen plasma was spectroscopically measured using the previously obtained photon efficiencies. It showed good agreement with results obtained by weight loss measurements. 16 refs., 7 figs., 1 tab.

  10. 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.

  11. 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.

  12. [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.

  13. 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 ɛm vs X2 curve of the solution. Heteromolecular entities with weak intermolecular forces experience larger hindrance leading to longer relaxation time τ.

  14. Crystallographic and spectroscopic study on a known orally active progestin.

    PubMed

    Ferraboschi, Patrizia; Ciuffreda, Pierangela; Ciceri, Samuele; Grisenti, Paride; Castellano, Carlo; Meneghetti, Fiorella

    2015-12-01

    6,17α-Dimethyl-4,6-pregnadiene-3,20-dione (medrogestone, 2) is for a long time known steroid endowed with progestational activity. In order to study its crystallographic and NMR spectroscopic properties with the aim to fill the literature gap, we prepared medrogestone following a traditional procedure. A careful NMR study allowed the complete assignment of the (1)H and (13)C NMR signals not only of medrogestone but also of its synthetic intermediates. The structural and stereochemical characterizations of medrogestone together with its precursor 17α-methyl-3-ethoxy-pregna-3,5-dien-20-one were described by means of X-ray analysis, allowing a deepened conformational investigation.

  15. Influence of heart motion on cardiac output estimation by means of electrical impedance tomography: a case study.

    PubMed

    Proença, Martin; Braun, Fabian; Rapin, Michael; Solà, Josep; Adler, Andy; Grychtol, Bartłomiej; Bohm, Stephan H; Lemay, Mathieu; Thiran, Jean-Philippe

    2015-06-01

    Electrical impedance tomography (EIT) is a non-invasive imaging technique that can measure cardiac-related intra-thoracic impedance changes. EIT-based cardiac output estimation relies on the assumption that the amplitude of the impedance change in the ventricular region is representative of stroke volume (SV). However, other factors such as heart motion can significantly affect this ventricular impedance change. In the present case study, a magnetic resonance imaging-based dynamic bio-impedance model fitting the morphology of a single male subject was built. Simulations were performed to evaluate the contribution of heart motion and its influence on EIT-based SV estimation. Myocardial deformation was found to be the main contributor to the ventricular impedance change (56%). However, motion-induced impedance changes showed a strong correlation (r = 0.978) with left ventricular volume. We explained this by the quasi-incompressibility of blood and myocardium. As a result, EIT achieved excellent accuracy in estimating a wide range of simulated SV values (error distribution of 0.57 ± 2.19 ml (1.02 ± 2.62%) and correlation of r = 0.996 after a two-point calibration was applied to convert impedance values to millilitres). As the model was based on one single subject, the strong correlation found between motion-induced changes and ventricular volume remains to be verified in larger datasets.

  16. Patterns of gas and liquid reflux during transient lower oesophageal sphincter relaxation: a study using intraluminal electrical impedance

    PubMed Central

    Sifrim, D; Silny, J; Holloway, R; Janssens, J

    1999-01-01

    Background—Belching has been proposed as a major mechanism underlying acid gastro-oesophageal reflux in normal subjects. However, the presence of oesophageal gas has not been measured directly but only inferred from manometry. 
Aims—To investigate, using intraluminal electrical impedance, the patterns of gas and liquid reflux during transient lower oesophageal sphincter (LOS) relaxations, the main mechanism of acid reflux in normal subjects. 
Methods—Impedance changes associated with the passage of gas were studied in vitro, and in vivo in cats. Oesophageal manometry, pH, and intraluminal electrical impedance measurements were performed in 11 normal subjects after a meal. 
Results—Gas reflux caused a sudden increase in impedance that propagated rapidly to the proximal oesophagus whereas liquid reflux induced a retrogressively propagated fall in impedance. Impedance showed gas or liquid reflux during most (102/141) transient LOS relaxations. When acid reflux occurred, impedance showed evidence of intraoesophageal retrograde flow of liquid in the majority (78%) of events. Evidence of gas retroflow was found in almost half (47%) of acid reflux episodes. When present together, however, liquid preceded gas on 44% of occasions. Overall, gas reflux occurred as the initial event in only 25% of acid reflux episodes. 
Conclusions—These findings suggest that in upright normal subjects, although belching can precipitate acid reflux, most acid reflux occurs as a primary event. 

 Keywords: belching; gastro-oesophageal reflux disease; oesophageal manometry; intraluminal electrical impedance; lower oesophageal sphincter PMID:9862825

  17. What Impedes or Enhances My Studying? The Interrelation between Approaches to Learning, Factors Influencing Study Progress and Earned Credits

    ERIC Educational Resources Information Center

    Hailikari, Telle Katriina; Parpala, Anna

    2014-01-01

    The aim of the study is to explore how students' experiences of enhancing and impeding factors and approaches to learning are related to students' study progress. A total of 93 students from the Faculty of Arts and Humanities participated in the study by answering a Learn-questionnaire regarding their experiences of the enhancing and impeding…

  18. 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…

  19. 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.

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

    NASA Astrophysics Data System (ADS)

    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 488 nm and 785 nm 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.

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

    PubMed Central

    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.

    2015-01-01

    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. 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. PMID:26160318

  2. 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.

  3. 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.

  4. 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.

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

    DOE PAGES

    Cao, R. X.; Sun, L.; Miao, B. 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 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

  6. 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.

  7. Spectroscopic Study of Low Mass Members of NGC 2244

    NASA Astrophysics Data System (ADS)

    Alty, Michelle; Ybarra, Jason E.; Román-Zúñiga, Carlos G.; Lada, Elizabeth A.

    2017-01-01

    The results of a near-infrared spectroscopic study of low-mass stars in open cluster NGC 2244 are presented. JH spectra of the stars were obtained using the FLAMINGOS instrument at KPNO. To determine cluster membership, we used Spitzer Space Telescope mid-infrared photometry along with X-ray detections from the Chandra X-ray Observatory. The stars were spectral typed using absorption line ratios and spectral shapes. The stars were then plotted on an H-R diagram along with theoretical isochrones. We discuss these results in context of cluster evolution in the Rosette Molecular Complex. Work supported, in part, by the Dr. John W. Martin Summer Science Research Institute at Bridgewater College.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Thoracic artificial lung impedance studies using computational fluid dynamics and in vitro models.

    PubMed

    Schewe, Rebecca E; Khanafer, Khalil M; Orizondo, Ryan A; Cook, Keith E

    2012-03-01

    Current thoracic artificial lungs (TALs) possess blood flow impedances greater than the natural lungs, resulting in abnormal pulmonary hemodynamics when implanted. This study sought to reduce TAL impedance using computational fluid dynamics (CFD). CFD was performed on TAL models with inlet and outlet expansion and contraction angles, θ, of 15°, 45°, and 90°. Pulsatile blood flow was simulated for flow rates of 2-6 L/min, heart rates of 80 and 100 beats/min, and inlet pulsatilities of 3.75 and 2. Pressure and flow data were used to calculate the zeroth and first harmonic impedance moduli, Z(0) and Z(1), respectively. The 45° and 90° models were also tested in vitro under similar conditions. CFD results indicate Z(0) increases as stroke volume and θ increase. At 4 L/min, 100 beats/min, and a pulsatility of 3.75, Z(0) was 0.47, 0.61, and 0.79 mmHg/(L/min) for the 15°, 45°, and 90° devices, respectively. Velocity band and vector plots also indicate better flow patterns in the 45° device. At the same conditions, in vitro Z (0) were 0.69 ± 0.13 and 0.79 ± 0.10 mmHg/(L/min), respectively, for the 45° and 90° models. These Z(0) are 65% smaller than previous TAL designs. In vitro, Z(1) increased with flow rate but was small and unlikely to significantly affect hemodynamics. The optimal design for flow patterns and low impedance was the 45° model.

  13. Effect of Yttrium Doping in Barium Zirconium Titanate Ceramics: A Structural, Impedance, and Modulus Spectroscopy Study

    NASA Astrophysics Data System (ADS)

    Badapanda, Tanmaya; Cavalcante, Laécio Santos; da Luz, Geraldo Eduardo; Batista, Nouga Cardoso; Anwar, Shahid; Longo, Elson

    2013-09-01

    In the current article, we studied the effect of yttrium [Y3+] ions' substitution on the structure and electric behavior of barium zirconate titanate (BZT) ceramics with a general formula [Ba1- x Y2 x/3](Zr0.25Ti0.75)O3 (BYZT) with [ x = 0, 0.025, and 0.05] which were prepared by the solid-state reaction method. X-ray diffraction patterns indicate that these ceramics have a single phase with a perovskite-type cubic structure. Rietveld refinement data confirmed [BaO12], [ZrO6], [TiO6], and [YO6] clusters in the cubic lattice. The Y3+ ions' effects on the electric conductivity behavior of BZT ceramics as a function of temperature and frequency are described, which are based on impedance spectroscopy analyses. The complex impedance plots display a double semicircle which highlights the influences of grain and grain boundary on the ceramics. Impedance analyses showed that the resistance decreased with the increasing temperature and resulted in a negative temperature coefficient of the resistance property in all compositions. Modulus plots represent a non-Debye-type dielectric relaxation which is related to the grain and grain boundary as well as temperature-dependent electric relaxation phenomenon and an enhancement in the mobility barrier by Y3+ ions. Moreover, the electric conductivity increases with the replacement of Ba2+ by Y3+ ions may be due to the rise in oxygen vacancies.

  14. Study of S-wave ray elastic impedance for identifying lithology and fluid

    NASA Astrophysics Data System (ADS)

    Gong, Xue-Ping; Zhang, Feng; Li, Xiang-Yang; Chen, Shuang-Quan

    2013-06-01

    In this paper, we derive an approximation of the SS-wave reflection coefficient and the expression of S-wave ray elastic impedance (SREI) in terms of the ray parameter. The SREI can be expressed by the S-wave incidence angle or P-wave reflection angle, referred to as SREIS and SREIP, respectively. Our study using elastic models derived from real log measurements shows that SREIP has better capability for lithology and fluid discrimination than SREIS and conventional S-wave elastic impedance (SEI). We evaluate the SREIP feasibility using 25 groups of samples from Castagna and Smith (1994). Each sample group is constructed by using shale, brine-sand, and gas-sand. Theoretical evaluation also indicates that SREIP at large incident angles is more sensitive to fluid than conventional fluid indicators. Real seismic data application also shows that SREIP at large angles calculated using P-wave and S-wave impedance can efficiently characterize tight gas-sand.

  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. 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.

  17. Theoretical and experimental study of the input impedance of the cylindrical cavity-backed rectangular slot antennas

    NASA Technical Reports Server (NTRS)

    Li, Ming-Yi; Hummer, Kenneth A.; Chang, Kai

    1991-01-01

    The authors study the input impedance of a cylindrical cavity-backed slot antenna based on mode matching and the complex Poynting theorem. Two cavity-backed slot antennas were fabricated to verify the theory. The numerical results agree very well with measurements. Two resonant frequencies were found from the input impedance. One resonant frequency is attributed to the rectangular slot and the other is due to the cavity. The slot length controls the first resonant frequency and has a much stronger effect on the input impedance at the antenna operating frequency as compared with the cavity length.

  18. Laser irradiated gas jet: A spectroscopic experimental and theoretical study

    SciTech Connect

    Lee, R.W.; Matthews, D.L.; Koppel, L.; Busch, G.E.; Charatis, G.; Dunning, M.J.; Mayer, F.J.

    1983-09-01

    We present x-ray spectroscopic measurements of the longitudinal electron density profile and the longitudinal and transverse electron temperature profiles for a laser irradiated gas jet. We attempt to verify our spectroscopic method by laser interferometry and by comparison of inferred quantities to those determined from laser plasma interaction simulations. Because temperature profiles were time dependent, we used a theoretical time dependent radiation transport code to analyze the data.

  19. Body fat measurement by bioelectrical impedance and air displacement plethysmography: a cross-validation study to design bioelectrical impedance equations in Mexican adults

    PubMed Central

    Macias, Nayeli; Alemán-Mateo, Heliodoro; Esparza-Romero, Julián; Valencia, Mauro E

    2007-01-01

    Background The study of body composition in specific populations by techniques such as bio-impedance analysis (BIA) requires validation based on standard reference methods. The aim of this study was to develop and cross-validate a predictive equation for bioelectrical impedance using air displacement plethysmography (ADP) as standard method to measure body composition in Mexican adult men and women. Methods This study included 155 male and female subjects from northern Mexico, 20–50 years of age, from low, middle, and upper income levels. Body composition was measured by ADP. Body weight (BW, kg) and height (Ht, cm) were obtained by standard anthropometric techniques. Resistance, R (ohms) and reactance, Xc (ohms) were also measured. A random-split method was used to obtain two samples: one was used to derive the equation by the "all possible regressions" procedure and was cross-validated in the other sample to test predicted versus measured values of fat-free mass (FFM). Results and Discussion The final model was: FFM (kg) = 0.7374 * (Ht2 /R) + 0.1763 * (BW) - 0.1773 * (Age) + 0.1198 * (Xc) - 2.4658. R2 was 0.97; the square root of the mean square error (SRMSE) was 1.99 kg, and the pure error (PE) was 2.96. There was no difference between FFM predicted by the new equation (48.57 ± 10.9 kg) and that measured by ADP (48.43 ± 11.3 kg). The new equation did not differ from the line of identity, had a high R2 and a low SRMSE, and showed no significant bias (0.87 ± 2.84 kg). Conclusion The new bioelectrical impedance equation based on the two-compartment model (2C) was accurate, precise, and free of bias. This equation can be used to assess body composition and nutritional status in populations similar in anthropometric and physical characteristics to this sample. PMID:17697388

  20. 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.

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

    PubMed

    Suess, Daniel L M; Britt, R David

    2015-09-01

    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 (57)Fe 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.

  2. 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…

  3. 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

  4. 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

  5. Study on the immobilization of anti-IgG on Au-colloid modified gold electrode via potentiometric immunosensor, cyclic voltammetry, and electrochemical impedance techniques.

    PubMed

    Fu, Yingzi; Yuan, Ruo; Tang, Dianping; Chai, Yaqin; Xu, Lan

    2005-01-15

    The immobilization of anti-IgG on Au-colloid modified gold electrodes has been investigated. A cleaned gold electrode was first immersed in a mercaptoethylamine (AET) solution, and then gold nanoparticles were chemisorbed onto the thiol groups of the mercaptoethylamine. Finally, anti-IgG was adsorbed onto the surface of the gold nanoparticles. Potentiometric immunosensor, cyclic voltammetry, and electrochemical impedance techniques were used to investigate the immobilization of anti-IgG on Au colloids. In the impedance spectroscopic study, an obvious difference of the electron transfer resistance between the Au-colloid modified electrode and the bare gold electrode was observed. The cyclic voltammogram tends to be more irreversible with increased anti-IgG concentration. Using the potentiometric immunosensor, the proposed technique is based on that the specific agglutination of antibody-coated gold nanoparticles, averaging 16 nm in diameter, in the presence of the corresponding antigen causes a potential change that is monitored by a potentiometry. It is found that the developed immunoagglutination assay system is sensitive to the concentration of IgG antigen as low as 12 ng mL(-1). Experimental results showed that the developed technique is in satisfactory agreement with the ELISA method, and that gold nanoparticles can be used as a biocompatible matrix for antibody or antigen immobilization.

  6. 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.

  7. 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.

  8. Spectroscopic Study on the Interaction of 4-dimethylaminochalcones with Phospholipids

    NASA Astrophysics Data System (ADS)

    Tomečková, V.; Revická, M.; Sassen, A.; Veliká, B.; Stupák, M.; Perjési, P.

    2014-11-01

    The ultraviolet-visible and fluorescence spectroscopic properties of 4'-dimethylaminochalcone ( 1a) and its cyclic analogs 2a-4a have been studied in the presence of phospholipid vesicles (i.e., egg yolk lecithin and dipalmitoylpho sphatidylcholine), bovine serum albumin (BSA), and lipoprotein particles (i.e., bovine serum albumin plus egg yolk lecithin). The spectral results showed that compounds 1a-4a formed hydrophobic interactions with the phospholipids, lipoproteins, and BSA at the polar/nonpolar interface. Compounds 3a and 4a exhibited the strongest hydrophobic interactions of all of the compounds tested towards the phospholipids. Compound 2a gave the best fluorescent fluorophore indicating interactions with the lipids, lipoproteins, and proteins. Fluorescent microscopic imaging of breast cancer cells treated with compounds 1a-4a revealed that they could be used to stain all of the cellular components and destroy the nuclear structure. Compounds 1a-4a were found to be concentrated predominantly on the surfaces of the liposomes and lipoproteins.

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

    PubMed

    Maurya, Anju; Rastogi, Shantanu

    2015-12-05

    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.

  10. Spectroscopic and Microscopic Study of Peroxyformic Pulping of Agave Waste.

    PubMed

    Hernández-Hernández, Hilda M; Chanona-Pérez, Jorge J; Vega, Alberto; Ligero, Pablo; Farrera-Rebollo, Reynold R; Mendoza-Pérez, Jorge A; Calderón-Domínguez, Georgina; Vera, Norma Güemes

    2016-10-01

    The peroxyformic process is based on the action of a carboxylic acid (mainly formic acid) and the corresponding peroxyacid. The influences of processing time (60-180 min), formic acid concentration (80-95%), temperature (60-80°C), and hydrogen peroxide concentration (2-4%) on peroxyformic pulping of agave leaves were studied by surface response methodology using a face-centered factorial design. Empirical models were obtained for the prediction of yield, κ number (KN) and pulp viscosity as functions of the aforementioned variables. Mathematical optimization enabled us to select a set of operational variables that produced the best fractionation of the material with the following results: pulp yield (26.9%), KN (3.6), and pulp viscosity (777 mL/g). Furthermore, this work allowed the description and evaluation of changes to the agave fibers during the fractionation process using different microscopic and spectroscopic techniques, and provided a comprehensive and qualitative view of the phenomena occurring in the delignification of agave fibers. The use of confocal and scanning electron microscopy provided a detailed understanding of the microstructural changes to the lignin and cellulose in the fibers throughout the process, whereas Raman spectroscopy and X-ray diffraction analysis indicated that cellulose in the pulp after treatment was mainly of type I.

  11. 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.

  12. 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.

  13. Spectroscopic studies of cryogenic fluids: Benzene in propane

    NASA Astrophysics Data System (ADS)

    Nowak, R.; Bernstein, E. R.

    1987-03-01

    Energy shifts and bandwidths for the 1B2u↔1A1g optical absorption and emission transitions of benzene dissolved in propane are presented as a function of pressure, temperature, and density. Both absorption and emission spectra exhibit shifts to lower energy as a function of density, whereas no shifts are observed if density is kept constant and temperature and pressure are varied simultaneously. Density is thus the fundamental microscopic parameter for energy shifts of optical transitions. The emission half-width is a linear function of both temperature and pressure but the absorption half-width is dependent only upon pressure. These results are interpreted qualitatively in terms of changes occurring in the intermolecular potentials of the ground and excited states. Both changes in shape of and separation between the ground and excited state potentials are considered as a function of density. Classical dielectric (Onsager-Böttcher), microscopic dielectric (Wertheim) and microscopic quantum statistical mechanical (Schweizer-Chandler) theories of solvent effects on solute electronic spectra are compared with the experimental results. Calculations suggest limited applicability of dielectric theories but good agreement between experiment and microscopic theory. The results demonstrate the usefulness of cryogenic solutions for high pressure, low temperature spectroscopic studies of liquids.

  14. Spectroscopic Studies of Dehydrogenation of Ammonia Borane in Carbon Cryogel

    SciTech Connect

    Sepehri, Saghar; Feaver, Aaron M.; Shaw, Wendy J.; Howard, Christopher J.; Zhang, Qifeng; Autrey, Thomas; Cao, Guozhong

    2007-12-27

    The reaction pathways leading to the thermal decomposition of solid state ammonia borane (AB) incorporated in carbon cryogels (CC) have been studied by spectroscopic methods. The time dependent thermal decomposition was followed by in situ 11B NMR and showed a significant increase in hydrogen release kinetics. Both 11B NMR and Fourier Transform Infrared Spectroscopy (FTIR) show new reaction products formed in the thermal decomposition of AB-CC that are assigned to reactions with surface oxygen groups. The results indicate that incorporation of AB in CC enhance kinetics due to reactions with residual surface-bound oxygen functional groups. The formation of new products with surface-O-B bonds is consistent with the greater reaction exothermicity observed when hydrogen is released from AB-CC materials. Scanning electron microscopy (SEM) shows different morphology of AB in ammonia borane – carbon cryogel (AB-CC) nanocomposite as compared to neat AB. Support for this work is provided by NSF (DMR-0605159), WTC, and EnerG2 LLC as well as the DoE Center of Excellence in Chemical Hydrogen Storage funded by the DOE H2 Program. FTIR experiments were performed in Professor Zhang’s lab in MSE department at UW. Part of this research was performed in the William R. Wiley Environmental Molecular Sciences Laboratory, located at the Pacific Northwest National Laboratory, which is operated by the Battelle for the U.S. Department of Energy.

  15. Molecular docking, spectroscopic studies and quantum calculations on nootropic drug.

    PubMed

    Uma Maheswari, J; Muthu, S; Sundius, Tom

    2014-04-05

    A systematic vibrational spectroscopic assignment and analysis of piracetam [(2-oxo-1-pyrrolidineacetamide)] have been carried out using FT-IR and FT-Raman spectral data. The vibrational analysis was aided by an electronic structure calculation based on the hybrid density functional method B3LYP using a 6-311G++(d,p) basis set. Molecular equilibrium geometries, electronic energies, IR and Raman intensities, and harmonic vibrational frequencies have been computed. The assignments are based on the experimental IR and Raman spectra, and a complete assignment of the observed spectra has been proposed. The UV-visible spectrum of the compound was recorded and the electronic properties, such as HOMO and LUMO energies and the maximum absorption wavelengths λmax were determined by the time-dependent DFT (TD-DFT) method. The geometrical parameters, vibrational frequencies and absorption wavelengths were compared with the experimental data. The complete vibrational assignments are performed on the basis of the potential energy distributions (PED) of the vibrational modes in terms of natural internal coordinates. The simulated FT-IR, FT-Raman, and UV spectra of the title compound have been constructed. Molecular docking studies have been carried out in the active site of piracetam by using Argus Lab. In addition, the potential energy surface, HOMO and LUMO energies, first-order hyperpolarizability and the molecular electrostatic potential have been computed.

  16. 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.

  17. 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.

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

    NASA Astrophysics Data System (ADS)

    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.

  19. 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

    2016-11-05

    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.

  20. A spectroscopic study of anomalous stellar populations in M67

    NASA Astrophysics Data System (ADS)

    McGahee, Courtney Elizabeth

    A population of stars exists in the old, open cluster M67, whose photometry, color magnitude diagram locations and associated evolutionary states cannot be explained by current, standard single star evolution theory. These stars are often referred to as "yellow straggler" stars. Yellow stragglers have been identified in multiple star clusters suggesting that these stars constitute a real population. Additionally, according to independent studies, at least some of the yellow straggler stars in M67 are likely cluster members. Therefore, cluster non-membership is not a sufficient explanation for the observed anomalous photometry of these stars. It is possible that the yellow stragglers occupy their precarious color magnitude diagram positions as a result of the evolution of mass transfer blue straggler stars. These are stars which have been formed by Roche Lobe overflow mass transfer in close binary systems. If this the case for the yellow stragglers, it is hypothesized that they could potentially exhibit two spectroscopic characteristics that can be indicative of this type of mass transfer system. Specifically, variable radial velocities can be used to indicate that the yellow stragglers exist in binary systems and enhancements of s-process elements in yellow stragglers can indicate Roche Lobe overflow mass transfer from a once asymptotic giant branch star which has since evolved into a white dwarf. This dissertation details the radial velocity survey and the chemical abundance analysis that have been conducted to investigate the yellow stragglers with regard to this hypothesis. The radial velocity survey revealed that eight of the ten yellow stragglers studied exhibit variable radial velocities indicating that the yellow straggler population of M67 possess a high binary frequency. However, the chemical abundance analysis revealed that none of the yellow stragglers exhibited enhancements of the s-process elements Y and Ba. Therefore, a history which involves Roche

  1. 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.

  2. 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.

  3. Spectroscopic study of graphene oxide membranes exposed to ultraviolet light

    SciTech Connect

    Schwenzer, Birgit; Kaspar, Tiffany C.; Shin, Yongsoon; Gotthold, David W.

    2016-05-16

    Research on graphene oxide (GO) as anything but a precursor material for synthesizing graphene started to pick up in 20061,2 and was soon followed by a first report of freestanding GO membranes (also referred to as GO paper) from R. S. Ruoff’s group at Northwestern University.3 The first GO membranes were prepared by vacuum filtration. More recently, larger scale GO membranes have been prepared by tape casting4 and other methods.5 In step with the development of new fabrication techniques, GO membranes are now tested for a wide array of applications6 ranging from energy-related4,7 or biomedical8 applications to more conventional uses for filtration9 and dehumidification.10 For all these proposed and implemented applications it remains to be seen how sensitive each of them is with respect to chemical and physical changes of the GO membranes over time. In this study, we report the effects of UV exposure on 2D-hierarchically stacked (Fig. S1 in ESI†) GO membranes. Macroscopically observable changes, such as darkening and mechanical deformation, have been correlated to chemical changes at the molecular level through spectroscopic measurements. Not only do the results of this work offer insights into the stability of GO membranes under UV light, but the findings will enable researchers, who are studying the use of these materials for different applications, to better understand the shelf life and packaging requirements for GO membranes. Furthermore, our results demonstrate the feasibility of deep ultraviolet (DUV) photolithography for graphene oxide-based devices. This approach is readily scalable as opposed to previous reports on photolithographic patterned reduction of GO to graphene by AFM,11 electron-beam12 or with an extreme ultraviolet (λ = 46.9 nm) laser.13

  4. 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...

  5. Optical and spectroscopic study of erbium doped calcium borotellurite glasses

    NASA Astrophysics Data System (ADS)

    Gomes, J. F.; Lima, A. M. O.; Sandrini, M.; Medina, A. N.; Steimacher, A.; Pedrochi, F.; Barboza, M. J.

    2017-04-01

    In this study, 10CaF2 - (29.9-0.4x)CaO - (60-0.6x)B2O3 - xTeO2 - 0,1Er2O3 (x = 10, 16, 22, 30 and 50 mol %) glasses were synthesized, and their optical and spectroscopic properties were investigated. X-ray diffraction, density, glass transition temperature (Tg), crystallization temperature (Tx), refraction index, luminescence, radiative lifetime and optical absorption measurements were carried out. Molar volume (Vm), thermal stability (Tx-Tg), electronic polarizability (αm), optical bang gap energy (Eg) and Judd-Ofelt (JO) parameters Ωt (2,4,6) were also calculated. The results are discussed in terms of tellurium oxide content. The increase of TeO2 in the glasses composition increases density, refractive index and electronic polarizability. The optical band gap energy decreases varying from 3.37 to 2.71 eV for the glasses with 10 and 50 mol% of TeO2, respectively. The optical absorption coefficient spectra show characteristic bands of Er3+ ions. Furthermore, these spectra in NIR region show a decrease of hydroxyl groups as a function of TeO2 addition. Luminescence intensity and radiative lifetimes at 1530 nm show an increasing with the TeO2 content. The JO parameters of Er:CaBTeX glasses follow the trend Ω2 > Ω4 > Ω6 and the quality factor values (Ω4/Ω6) were between 1.37 and 3.07. By comparing the measured lifetime with the calculated radiative decay time, quantum efficiency was calculated. The luminescence emission intensity at 1530 nm decreases with the increase of temperature. The lifetime values show a slight trend to decrease with the temperature increase, from 300 to 420 K, for all the samples.

  6. Spectroscopic studies of cathode materials for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Totir, Dana Alexa

    2000-10-01

    Structural changes that occur during electrochemical cycling of lithium-ion battery cathode materials have been investigated using in situ spectroscopic techniques. A new method was developed for the preparation of carbon and binder free cathodes utilizing powder materials of interest for commercial batteries. The extraordinary quality of the cyclic voltammetric curves recorded for this type of electrodes during the in situ measurements allows direct correlations to be made between the state of charge of the material and its structural and electronic characteristics. LiCoO2, LiMn2O4 and LiCo0.15Ni 0.85O2 electrodes were evaluated using cycling voltammetry and the mean diffusion coefficient for Li-ions in the lattice (DLi) was calculated for LiMn2O4. LiMn2O4 electrodes prepared by this technique have been studied in situ using Mn K-edge XAS. Data analysis for the species formed at different potentials indicated a contraction of the lattice associated with the increase in the oxidation state of manganese. In situ Raman spectra of particles of LiMn2O 4, and LiCoO2 embedded in Au and also of KS-44 graphite and carbon microfibers MCF28 embedded in thermally annealed Ni have been recorded as a function of the applied potential. Fe K-edge XAFS of pyrite electrodes in a Li/PEO(LiClO4)/FeS 2 cell and S K-edge XANES measurements of a FeS2 electrode in a non-aqueous electrolyte have been acquired as a function of the state of charge. The studies have clearly evidenced the formation of metallic Fe and Li2S as intermediates after 4 e- discharge and the formation of Li2FeS2 after 2 e- recharge. While Fe K-edge studies have indicated that there is no change in the Fe environment and oxidation state upon 4 e- recharge, the results obtained from S K-edge studies are inconclusive for this stage. Finally, in situ Co K-edge XAFS data were obtained for the first time during the electrochemical cycling of electrodeposited Co(OH) 2 films in alkaline solutions. The results support

  7. 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

  8. X-ray spectroscopic studies of secondary battery materials

    NASA Astrophysics Data System (ADS)

    Kostov, Svilen Dimitar

    1998-09-01

    X-ray spectroscopic methods, both NEXAFS and EXAFS were used in the study of the structural and electronic properties of different types of new battery materials. NEXAFS analysis of the spectra of Lisb{1-x}CoO2 secondary battery cathodes revealed that the addition of Li proceeds is strongly correlated to the increase in electronic charge on the Co ion. A structural phase transition is confirmed for x=0.5. The presence of Mnsp{+2} is detected in the conventionally made LiMnOsb2 cathodes but not in ones prepared according to the new ADL process. Lisb{x}Vsb6Osb{13} cathode material, where 0≤ x≤6, was measured using x-ray absorption, EPR and NMR techniques. The intercalation mechanism involves a conversion of Vsp{+5} to Vsp{+4} in Vsb6Osb{13} until the composition Lisb2Vsb6Osb{13} is reached. Further addition of lithium is accompanied by the conversion of Vsp{+4} to Vsp{+3} until Lisb8Vsb6Osb{13} is reached. The process is complicated and involves structural phase changes and increasing structural disorder within the multi-phase system as Li concentration is increased. Studies of LiNi/CoOsb2 intercalation cathodes prepared by a novel sol-gel technique suggests that although the partial substitution of Co for Ni stabilizes the system by removing Nisp{+2}, a Jahn-Teller type structural distortion in the predominantly Nisp{=3} system persists. In-situ EXAFS measurements of the pyrite cathode in a new Li/CPE/FeSsb2 showed two distinct environments of the Fe ion, which were interpreted as those of metallic Fe and residual FeSsb2 at high lithium concentration, and Lisb2FeSsb2 and residual FeSsb2 at low lithium concentration. The formation of FeS was not detected. A new type of hydrogen ion battery incorporating a MnSOsb4sp&*slash;Hsb2O based cathode and polymer electrolyte was also studied. Heavily cycled and discharged cathodes showed an almost identical Mn local structure to that of single cycled ones. The Mn environment becomes very different in the charged cathodes

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. Structural, spectroscopic and theoretical study of novel ephedrinum salt

    NASA Astrophysics Data System (ADS)

    Ivanova, B.; Kolev, T.; Lamshöft, M.; Mayer-Figge, H.; Seidel, R.; Sheldrick, W. S.; Spiteller, M.

    2010-05-01

    Ephedrinum violurate dihydrate was synthesized, spectroscopically and structural elucidated. The data are compared with those of the free-base ephedrine hemihydrate. Discussion on the stable conformer of the ephedrinum cation is carried out. Quantum chemical calculations were performed for the theoretical elucidation of the conformational preference of the ephedrinum cation and its vibrational properties. The model systems neutral ephedrine hemihydrate ( 1) and violurate salt dihydrate ( 2) are elucidated.

  14. Electrochemical impedance spectroscopy study of high-palladium dental alloys. Part II: behavior at active and passive potentials.

    PubMed

    Sun, D; Monaghan, P; Brantley, W A; Johnston, W M

    2002-05-01

    Electrochemical impedance spectroscopic (EIS) analyses were performed on three high-palladium alloys and a gold-palladium alloy at active and passive potentials in five electrolytes that simulated body fluid and oral environmental conditions. All four alloys were previously found to have excellent corrosion resistance in these in vitro environments. Before performing the EIS analyses, alloy specimens were subjected to a clinically relevant heat treatment that simulated the firing cycles for a dental porcelain. It was found that the EIS spectra varied with test potential and electrolyte. Diffusional effects, related to the dealloying and subsequent surface enrichment in palladium of the high-palladium alloys, along with species adsorption and passivation, were revealed at both active and passive potentials, although these effects were more evident at the passive potentials.

  15. Esophageal solid bolus transit: studies using combined multichannel intraluminal impedance and manometry in healthy volunteers.

    PubMed

    Chen, C L; Yi, C H; Chou, A S B; Liu, T T

    2013-01-01

    The purpose of this study is to apply combined multichannel intraluminal impedance and esophageal manometry (MII-EM) to test esophageal function during solid swallowing in a normal healthy population. We determined whether combined MII-EM with solid bolus is more sensitive than that with viscous bolus in the detection of motility abnormality. Eighteen healthy volunteers (11 men and 7 women; mean age 22 years, range 20-26 years) underwent combined MII-EM with a catheter containing four impedance-measuring segments and five solid-state pressure transducers. Each subject received 10 viscous and 10 solid materials. Tracings were analyzed manually for bolus presence time, total bolus transit time, contraction amplitude, duration, and onset velocity. Three hundred and sixty swallows including viscous and solid materials were analyzed. Contraction amplitude for the viscous swallows was higher at 20 cm above the lower esophageal sphincter (LES) (P= 0.049) but lower at 15 cm above the LES (P < 0.001). Duration of contractions for the solid swallows was longer at 15 cm (P= 0.002) and 10 cm above the LES (P= 0.011) compared with viscous swallows. The total bolus transit time for solid was significantly shorter than that for viscous boluses (6.8 vs. 7.7 seconds, P < 0.001). Bolus presence time appeared to be similar between viscous and solid boluses (except in the proximal esophagus). The percentage of swallows with ineffective peristalsis by manometry, as well as those with incomplete bolus transit by impedance, did not differ between viscous and solid swallows. The proportion of manometrically ineffective solid swallows with incomplete bolus transit was greater than that of viscous swallows (62.1% vs. 34.8%, P= 0.05). Application of solid boluses may potentially enhance diagnostic capability of esophageal function testing. Solid boluses can be regarded as a valuable complement to viscous boluses in the detection of esophageal motility abnormalities when applied with

  16. Biomechanical wall properties of the human rectum. A study with impedance planimetry.

    PubMed Central

    Dall, F H; Jørgensen, C S; Houe, D; Gregersen, H; Djurhuus, J C

    1993-01-01

    Biomechanical properties of the rectal wall were studied in 17 healthy adult volunteers (nine men and eight women). With impedance planimetry it is possible to obtain simultaneous measurements of pressure and rectal cross sectional area (CSA) during balloon inflations. Rectal distensions were done with an intraluminal balloon using specified pressures up to 40 cmH2O above baseline rectal pressure. Balloon inflation elicited a phase of rapid increase in rectal CSA followed by a phase of slow increase until a steady state was reached. Steady state occurred within 67 to 140 seconds with the shortest period at the highest distension pressures. Steady state rectal CSA values had a non-linear relation to increasing distension pressure. Rectal CSA values in women showed a tendency of being slightly higher than male values at all pressure steps with a significant difference at 3 and 5 cm H2O. Biomechanical parameters were calculated from rectal CSA pressure relations. Circumferential wall tension increased in a linear way. Rectal compliance decreased in a non-linear way with no further decline between 30 and 40 cmH2O. The pressure elastic modulus increased steeply until a distension pressure of 35 cmH2O with no further increase to 40 cmH2O. This suggests that rectal tone is reduced as the muscle fails to resist further distension at 35 cmH2O and higher pressures. Impedance planimetry offers new possibilities for investigation of anorectal physiology through the study of segmental biomechanical wall properties of the human rectum. PMID:8244148

  17. 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

  18. 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

  19. 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.

  20. 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.

  1. 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.

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

    NASA Astrophysics Data System (ADS)

    Stimulated emission pumping (SEP) spectroscopy was used on acetylene and on formyl radical. An attempt was made for pattern recognition based on statistics; a method was invented that combined CNPI (complete nuclear permutation-inversion) group theory and SCC (spectral cross-correlation). But the direction away from statistical pattern recognition back to traditional spectroscopic pattern recognition was taken. Vibrational states and quantum numbers are discussed. For the formyl radical, the fluorescence excitation spectrum was recorded and a rotational analysis of the 0(sup 0)(sub 0) band performed.

  3. 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.

  4. 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

  5. An impedance device for study of multisegment hemodynamic changes during orthostatic stress

    NASA Astrophysics Data System (ADS)

    Montgomery, L. D.; Hanish, H. M.; Marker, R. A.

    1989-11-01

    Definition of multisegment hemodynamic changes that take place in the body would provide a more complete understanding of the physiologic responses to various orthostatic stress techniques. A self-contained impedance device is described which may be used to measure the electrical transmission characteristics produced by blood flow and volume changes in six segments of the human body during head-up tilt, bed rest, and lower body negative pressure. The device consists of a module that contains the electronics for the impedance system, a separate controller/multiplexer, a personal computer interface/analog to digital conversion/power supply system, and the associated computer control softwave. The instrument is linear over a range of 0 to 200 ohms; provides analog outputs of base impedance, phase angle, pulsatile impedance change, and the first derivative of the pulsatile impedance changes; and can be used to automatically record basal impedance values into spread-sheet format with cycle times between 12 s and 1 h. Typical results are presented to illustrate its application in aerospace research.

  6. An impedance matching of femoral-popliteal arterial grafts: a theoretical study.

    PubMed

    Hirayama, H; Nishimura, T; Fukuyama, Y

    1997-05-01

    We have proposed a mathematical method to investigate the matching conditions for an arterial graft in the femoral-popliteal region from a mechanical stand-point. Pulsatory blood flow, arterial wall motions, and conservation law are expressed by linear dynamical equations based on strict mechanical and constitutional considerations. To express the physiological blood flow in an actual arterial system, the tethering effects from the surrounding tissue and wall tensions were incorporated. The physiological parameters of arterial wall and tethering were utilized from reported experimental data. By complex analysis, mathematical expressions for the local impedance and reflection coefficient were obtained. They include not only blood properties such as viscosity and density, but also arterial properties including elastic modulus, radius, Poisson ratio, wall thickness, wall tension, frequency, and tethering effects from surrounding tissue. A matching condition was defined for minimizing the local impedance and reflection coefficient. The biophysical background was to reduce any mechanical mismatches, thus minimizing the disturbance of the flow velocity profile and shear stress distribution within the artery. Impedance matching in turn diminishes the negative factors for graft substitution represented by intimal hyperplasia and thrombosis. The calculated impedance and reflection coefficient inversed parabolically to functions of the resistance of the host artery, and there was one host arterial resistance that minimized the impedance and reflection coefficient. The present analysis revealed that for matching host artery with an elevated resistance, the dynamic elastic modulus of the wall of the graft that minimizes the impedance and reflection coefficient was increased. This indicates that for a host artery with a high resistance, an impedance matched stiff wall graft is preferable. For a large radius and a compliant host artery on the other hand, a large compliant graft

  7. AC impedance spectroscopy and conductivity studies of Dy doped Bi4V2O11 ceramics

    NASA Astrophysics Data System (ADS)

    Bag, Sasmitarani; Das, Parthasarathi; Behera, Banarji

    2017-03-01

    The ac impedance and conductivity properties of Dy doped Bi4V2 - x Dy x O11 (x = 0.05, 0.10, 0.15 and 0.20) ceramics prepared by solid-state reaction technique, in a wide frequency range at different temperatures have been studied. All the samples exhibited β-type phase orthorhombic structure at room temperature. The Nyquist plot confirmed the presence of both grain and grain boundary effects for all Dy doped samples. Double relaxation behavior was also observed. The grain and grain boundary resistance decreases with rise in temperature for all the concentration and exhibits a typical negative temperature co-efficient of resistance (NTCR) behavior. An analysis of the electric modulus suggests the possible hopping mechanism for electrical transport processes of all the materials. The ac conductivity spectrum obeys Jonscher's universal power law. DC conductivity of the materials were also studied and values of the activation energy found to be 0.40, 0.49, 0.73 and 0.78 eV for the compositions x = 0.05, 0.10, 0.15 and 0.20, respectively, at different temperatures (150-375 °C).

  8. Using Spectroscopic Profiles to Study the Morphology of Comets

    NASA Astrophysics Data System (ADS)

    Harris, Ien; Pierce, Donna M.; Cochran, Anita L.

    2016-10-01

    We have used the integral-field unit spectrograph (the George and Cynthia Mitchell Spectrograph) on the 2.7m Harlan J. Smith telescope at McDonald Observatory to obtain spectroscopic images of the comae of several comets. The images were obtained for various radical species (C2, C3. CH, CN, NH2). Radial and azimuthal average profiles of the radical species were created to enhance any observed cometary coma morphological features. We compare the observed coma features across the observed species and over the different observation periods in order to constrain possible rotational states of the observed comets. We will present results for several comets, including 2009P1 (Garradd). This work was funded by NASA's Planetary Atmospheres program (Award No. NNX14AH186).

  9. A Spectroscopic Study of Anomalous Stellar Populations in M67

    NASA Astrophysics Data System (ADS)

    McGahee, Courtney; King, Jeremy R.; Deliyannis, Constantine P.

    2015-01-01

    A population of so-called "yellow straggler" stars occupy precarious color magnitude diagram positions in the old open cluster M67 that cannot be explained by standard single star evolution theory. These stars may have been formed by Roche lobe overflow mass transfer in close binary systems. We present new radial velocities and spectroscopic abundances of M67 yellow stragglers to test this hypothesis, and find that these objects possess a high binary frequency, but no enhancements of s-process elements that might be a smoking gun signature of mass transfer. Observations were conducted using the WIYN 3.5 m telescope in conjunction with the HYDRA spectrograph at Kitt Peak National Observatory. Support for this project was provided by NSF grants AST 09-08342, AST 0607567, and AST 1211699.

  10. Models of chemical biosignatures - a vibrational spectroscopic study

    NASA Astrophysics Data System (ADS)

    Bödeker, B.; Böttger, U.; Hübers, H.-W.; deVera, J.-P.; Fox, S.; Strasdeit, H.

    2013-09-01

    Investigating possible biosignatures is of central interest in the search for the oldest traces of terrestrial life. Possible biosignatures are: (i) physical structures, such as fossilized single-celled or colonyforming microorganisms; (ii) biomolecules and their altered residues (chemical biosignatures); (iii) altered element, isotope and mineral compositions in former microbial habitats and related effects caused by metabolic activity [1]. New insights in this field of research are also important in the search for life on other planets and moons, especially Mars. However, abiotically formed organic compounds are widely distributed in the universe. Therefore, in future Mars missions, it will be essential to know whether organic molecules are actually of biological origin. Here, we describe the syntheses and spectroscopic (Raman and infrared) properties of artificial chemical biosignatures that might help answering this question.

  11. Spectroscopic study of Er:Sm doped barium fluorotellurite glass.

    PubMed

    Bahadur, A; Dwivedi, Y; Rai, S B

    2010-09-15

    In this paper, we report the physical and spectroscopic properties of Er(3+), Sm(3+) and Er(3+):Sm(3+) ions codoped barium fluorotellurite (BFT) glasses. Different Stokes and anti-Stokes emissions were observed under 532 nm and 976 nm laser excitations. Energy transfer from Er(3+) ion to Sm(3+) ion was confirmed on the basis of luminescence intensity variation and decay curve analysis in both the cases. Under green (532 nm) excitation emission intensity of Sm(3+) ion bands improves whereas on NIR (976 nm) excitation new emission bands of Sm(3+) ions were observed in Er:Sm codoped samples. Ion interactions and the different energy transfer parameters were also calculated.

  12. Raman spectroscopic study of a genetically altered kidney cell

    NASA Astrophysics Data System (ADS)

    Joshi, Joel; Garcia, Francisco; Centeno, Silvia P.; Joshi, N. V.

    2008-02-01

    A Raman spectroscopic investigation of a genetically altered Human Embryonic Kidney Cell (HEK293) along with a pathologically normal cell has been carried out by a conventional method. The genetic alteration was carried out with a standard protocol by using a Green Fluorescence Protein (GFP). Raman spectra show that there are dramatic differences between the spectrum obtained from a genetically altered cell and that obtained from a pathologically normal cell. The former shows three broad bands; meanwhile the latter shows several sharp peaks corresponding to the ring vibrational modes of Phen, GFP and DNA. The present analysis provides an indication that the force field near Phen located at 64, 65 and 66 was altered during the genetic transformation. The Raman spectrum could be a direct experimental evidence for substantial modifications triggered due to the expression of specific genes.

  13. Study of human serum albumin-TiO(2) nanocrystalline electrodes interaction by impedance electrochemical spectroscopy.

    PubMed

    Oliva, F Y; Avalle, L B; Macagno, V A; De Pauli, C P

    2001-07-02

    The adsorption of human serum albumin (HSA) onto nanocrystalline TiO(2) electrodes was studied by electrochemical impedance spectroscopy (EIS) in function of pH and electrode potential. The characterization and physico-chemical properties of the TiO(2) electrode were investigated by scanning electron microscopy (SEM), UV-photoelectron spectroscopy (UPS), cyclic voltammetry and capacitance measurements. The impedance response of the particulate TiO(2) electrode/protein interface was fitted using an equivalent circuit model to describe the adsorption process. The adsorbed protein layer, which is formed as soon as the protein is injected into the solution and becomes in contact with the electrode, was investigated as a function of electrode potential and solution pH. The measurements were performed under pseudo-steady-state and steady-state conditions, which gave information about the different states of the system. With the pseudo-steady state measurements, it was possible to determine two rate constants of the protein adsorption process, which correspond to two different states of the protein. The shortest one was associated with the first contact between the protein and the substrate and the second relaxation time, with the protein suffering an structural rearrangement due to the interaction with the TiO(2) electrode. It was detected that at sufficiently long times (approx. 1 h, where the system was under steady state conditions), a quasi-reversible protein adsorption mechanism was established. The measurements performed as a function of frequency under steady-state conditions, an equivalent circuit with a Warburg element gave the better fitting to data taken at -0.585 V closer to the oxide flat band potential and it was associated with protein diffusion. Experimental results obtained at only one frequency as a function of potential could be fitted to a model that takes into account non-specific and probable specific protein adsorption, which renders to be

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Electrical Impedance Tomography: a new study method for neonatal Respiratory Distress Syndrome?

    PubMed

    Chatziioannidis, I; Samaras, T; Nikolaidis, N

    2011-07-01

    Treatment of cardiorespiratory system diseases is a procedure that usually demands data collection on terms of the anatomy and the operation of the organs that are under study. Electrical Impedance Tomography (EIT) is an alternative approach, in comparison to existing techniques. With EIT electrodes are placed in the perimeter of the human body and images of the estimated organ are reconstructed, using the measurement of its impendence (or resistance) distribution and determining its alteration through time, while at the same time the patient is not exposed to ionizing radiation. Its clinical use presupposes the correct placement of the electrodes over the perimeter of the human body, the rapid data collection and electrical safety. It is a low cost technique and it is implemented near the patient. It is able to determine the distribution of ventilation, blood supply, diffused or localized lung defects, but it can also estimate therapeutic interventions or alteration to assisted ventilation of the neonate. EIT was developed at the beginning of the 1980s, but it has only recently begun to be implemented on neonates, and especially in the study of their respiratory system function. The low rate of image analysis is considered to be a drawback, but it is offset by the potential offered for the estimation of lungs' function (both under normal and pathological conditions), since ventilation and resistance are two quite similar concepts. In this review the most important studies about EIT are mentioned as a method of estimating respiratory distress syndrome in neonates. In terms of the above mentioned development, it is supposed that this technique will offer a great amount of help to the doctor in his / her estimations of the cardiorespiratory system and to his / her selection of the best intervening strategies.

  20. Optical properties of InN studied by spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Chunya, Ye; Wei, Lin; Jin, Zhou; Shuping, Li; Li, Chen; Heng, Li; Xiaoxuan, Wu; Songqing, Liu; Junyong, Kang

    2016-10-01

    With recently developed InN epitaxy via a controlling In bilayer, spectroscopic ellipsometry (SE) measurements had been carried out on the grown InN and the measured ellipsometric spectra were fitted with the Delta Psi2 software by using a suitable model and the dispersion rule. The thickness was measured by a scanning electron microscope (SEM). Insight into the film quality of InN and the lattice constant were gained by X-ray diffraction (XRD). By fitting the SE, the thickness of the InN film is consistent with that obtained by SEM cross-sectional thickness measurement. The optical bandgap of InN was put forward to be 1.05 eV, which conforms to the experimental results measured by the absorption spectrum and cathodoluminescence (CL). The refractive index and the extinction coefficient of interest were represented for InN, which is useful to design optoelectronic devices. Project supported by the State Key Development Program for Basic Research of China (No. 2012CB619301), the National High Technology Research and Development Program of China (No. 2014AA032608), the National Natural Science Foundation of China (Nos. 11204254, 11404271), and the Fundamental Research Funds for the Central Universities (Nos. 2012121014, 20720150027).

  1. Acid doping of polyaniline: Spectroscopic and electrochemical studies

    SciTech Connect

    Hatchett, D.W.; Josowicz, M.; Janata, J.

    1999-12-16

    A detailed investigation of the acid doping behavior of polyaniline has led to a robust and reproducible procedure for controlled adjustment of the redox state of dry polyaniline films. The initial step in this procedure is the casting of PANI films from formic acid. The subsequent exchange of the trapped formic acid for other primary dopants obtained from mono- and polyprotic acids (e.g., CH{sub 3}COO{sup {minus}}, BF{sub 4}{sup {minus}}, HSO{sub 4}{sup {minus}}, SO{sub 4}{sup 2{minus}}, H{sub 2}PO{sub 4}{sup {minus}}, and HPO{sub 4}{sup 2{minus}}) is demonstrated. The voltammetric and the spectroscopic behavior of the PANI doped with different anions indicate that both the protons and the anions of dopant acids influence the structure and redox properties of the polymer. The redox state of PANI doped with homologous series of chloroacetic and carboxylic acids correlates with the pK{sub a} of the dopant acid. These results show that it is possible to prepare the polymer with a desired oxidation state according to the pK{sub a} of the dopant acid of a given homologous series. The exchange of the formic acid for both stronger and weaker doping acid can be repeatedly accomplished by electrochemical cycling.

  2. 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.

  3. 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.

  4. 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

    2015-01-01

    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.

  5. Electric impedance platelet aggregometry in cardiac surgery patients: A comparative study of two technologies.

    PubMed

    Ranucci, Marco; Baryshnikova, Ekaterina; Crapelli, Giulia Beatrice; Ranucci, Matteo; Meloni, Silvia; Pistuddi, Valeria

    2016-01-01

    Platelet function tests are suggested to assess platelet reactivity before cardiac and major non-cardiac surgery. Different point-of-care platelet function tests are available. Among these, electric impedance platelet aggregometry (EIPA) (Multiplate®, MP) is one of the most widely used techniques. Recently, a new EIPA system (Rotem Platelet®, RP) was released. This is a comparative study of platelet function measured with MP and RP. Fifty cardiac surgery patients were admitted to this study. All the patients received a preoperative platelet function test with both the MP and the RP; for each technology, two tests were performed: the ADPtest (investigating P2Y12 receptor platelet reactivity) and the TRAPtest (investigating the thrombin-dependent platelet reactivity). ADP-based platelet reactivity values demonstrated a significant (p = 0.019) correlation between the MP and the RP; and a marginally significant (p = 0.042) correlation for TRAP-based tests. The Bland-Altman analysis of the ADPtest demonstrated a positive bias of 5.94 units (MP > RP) and a percentage error of 88%. For the TRAPtest, there was a positive bias of 12 units (MP > RP) and a percentage error of 89%. In patients who were preoperatively treated with P2Y12 receptor inhibitors, only the MP ADPtest was positively associated with the days from drug discontinuation (p = 0.003). Platelet function assessment with RP greatly differs from the equivalent MP measure, and no correction value can be applied due to the low level of precision. This applies both to ADPtest and TRAPtest. The MP ADPtest is more reliable for platelet reactivity after discontinuation of P2Y12 receptor inhibitors.

  6. 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

  7. Cell Electrical Impedance as a Novel Approach for Studies on Senescence Not Based on Biomarkers

    PubMed Central

    Cha, Jung-Joon; Park, Yangkyu; Yun, Joho; Kim, Hyeon Woo; Park, Chang-Ju; Kang, Giseok; Jung, Minhyun; Pak, Boryeong; Jin, Suk-Won

    2016-01-01

    Senescence of cardiac myocytes is frequently associated with heart diseases. To analyze senescence in cardiac myocytes, a number of biomarkers have been isolated. However, due to the complex nature of senescence, multiple markers are required for a single assay to accurately depict complex physiological changes associated with senescence. In single cells, changes in both cytoplasm and cell membrane during senescence can affect the changes in electrical impedance. Based on this phenomenon, we developed MEDoS, a novel microelectrochemical impedance spectroscopy for diagnosis of senescence, which allows us to precisely measure quantitative changes in electrical properties of aging cells. Using cardiac myocytes isolated from 3-, 6-, and 18-month-old isogenic zebrafish, we examined the efficacy of MEDoS and showed that MEDoS can identify discernible changes in electrical impedance. Taken together, our data demonstrated that electrical impedance in cells at different ages is distinct with quantitative values; these results were comparable with previously reported ones. Therefore, we propose that MEDoS be used as a new biomarker-independent methodology to obtain quantitative data on the biological senescence status of individual cells. PMID:27812531

  8. In Vitro and In Vivo Studies for a Bio-Impedance Vital-Sign Monitor

    DTIC Science & Technology

    2006-10-01

    Patterson R: Bioelectric impedance measurement. In: Bronzino JD. The biomedical engineering handbook. Boca Raton, CRC Press, 1995. pp 1223-1230. 35 11...28. Cohen A: Biomedical signals: Origin and dynamic characteristics; frequency domain analysis. In: Bronzino JD. The biomedical engineering handbook

  9. A Basic Study About Multi Channel Measurement of Skin Impedance Vector Loci on the Acupuncture Points

    DTIC Science & Technology

    2007-11-02

    Agency Name(s) and Address(es) US Army Research, Development & Standardization Group (UK) PSC 802 Box 15 FPO AE 09499-1500 Sponsor/Monitor’s Acronym(s...each measurement we perform. Additionally, we applied the results obtained to per- foming 4 channel measurments of skin impedance vector loci around

  10. X-ray spectroscopic methods in the studies of nonstoichiometric TiO2-x thin films

    NASA Astrophysics Data System (ADS)

    Kollbek, K.; Sikora, M.; Kapusta, Cz.; Szlachetko, J.; Zakrzewska, K.; Kowalski, K.; Radecka, M.

    2013-09-01

    X-ray spectroscopic techniques have been used in the studies of electronic and structural properties of nonstoichiometric TiO2-x thin films obtained by reactive sputtering from Ti target. Films characterisation has been completed by means of X-ray diffraction in grazing incidence, GID, UV Raman and impedance spectroscopy, optical spectrophotometry, 1s3p Resonant X-ray Emission Spectroscopy, RXES, and X-ray Photoelectron Spectroscopy, XPS. Stoichiometric thin films of TiO2 are composed of a well-crystallised anatase-rutile mixture with the predominance of anatase while the films with higher oxygen deficit are amorphous to larger extent. Oxidation state changes from Ti4+ in stoichiometric films towards Ti3+ upon increasing departure from stoichiometric composition. This change is accompanied by the significant decrease in the electrical resistivity. The comparison of band gap energies, determined independently from optical and valence band X-ray absorption/emission spectra is good assuming direct allowed transitions.

  11. Impedance function study for cylindrical tanks surrounded by an earthen embankment

    SciTech Connect

    Houston, T.W.; Mertz, G.E.

    1995-12-31

    The Department of Energy (DOE) operates many which are used to store radioactive waste material. The original design of the tanks was often based on criteria which did not meet current seismic codes. As a result DOE is undertaking a comprehensive review of the adequacy of these structures to meet current seismic standards. This comprehensive review includes an evaluation of soil-structure interaction. One method available for performing soil structure interaction analyses of structures couples a discrete model of the structure to a lumped parameter model of the soil. This method requires the knowledge of the expected dynamic stiffness and damping functions of the rigid, massless structure resting on the soil. These are commonly referred to as the impedance functions. Lumped parameter analysis is cost effective for the surface and embedded structure cases where impedance functions are available in the literature. For a complex case with the structure located on the surface surrounded by an embankment, the impedance functions must be established prior to using a lumped parameter model approach. The present paper describes the development of horizontal impedance functions for the structure surrounded by an embankment which are developed using a finite element approach as implemented by SASSI. Impedance functions for vertical, torsional, and rocking degrees of freedom can be developed in a similar manner. These functions are easily incorporated into simple models which provide conceptual and physical insight to the response of structures. These models provide both a check of more sophisticated methods, and, due to their simplicity, permit assessment of a wide range of site and structural parameters that my affect the dynamic response of structural systems.

  12. Electrochemical and spectroscopic study of octadecyltrimethylammonium bromide/DNA surfoplexes.

    PubMed

    Rodríguez-Pulido, Alberto; Aicart, Emilio; Junquera, Elena

    2009-04-21

    The use of cationic micelles consisting of octadecyltrimethylammonium bromide (C18TAB) to compact calf thymus DNA has been investigated in aqueous buffered solution at 310.15 K by means of conductometry, electrophoretic mobility, and several fluorescence spectroscopy methods. The results indicate that C18TAB micelles, consisting of 44 monomers on average, may compact DNA molecule by an electrostatic interaction that takes place at the cationic spherical micelle surface. The surfoplexes thus formed show a surface density charge that goes from negative to positive values at a Lmic/D mass ratio of around 1.0 (where Lmic and D are the masses of micellized cationic surfactant and DNA), called the isoneutrality ratio (Lmic/D)phi. Values of this characteristic parameter, determined in this work not only from the electrochemical experimental data but also from spectroscopic measurements, are in very good agreement with those ones calculated from molecular parameters and some other properties also obtained in this work. The electrostatic character of the DNA-micelle interaction has been confirmed by analyzing the decrease in fluorescence emission of the fluorophore ethidium bromide, EtBr, initially intercalated between DNA base pairs, as long as the surfoplexes are formed. Fluorescence anisotropy experiments have revealed that micelle packing becomes more rigid in the presence of DNA, but once the surfoplex is formed, the fluidity increases with the Lmic/D mass ratio, attaining its maximum when the isoneutrality ratio is exceeded. This fact, together with the net positive charge of the surfoplexes with the Lmic/D mass ratio over the isoneutrality ratio, makes this regimen of lipid and DNA content the optimum for efficiency in the transfection process.

  13. Assessment of Ventilation Distribution during Laparoscopic Bariatric Surgery: An Electrical Impedance Tomography Study.

    PubMed

    Stankiewicz-Rudnicki, Michal; Gaszynski, Wojciech; Gaszynski, Tomasz

    2016-01-01

    Introduction. The aim of the study was to assess changes of regional ventilation distribution at the level of the 3rd intercostal space in the lungs of morbidly obese patients as a result of general anaesthesia and laparoscopic surgery as well as the relation of these changes to lung mechanics. We also wanted to determine if positive end-expiratory pressure of 10 cm H2O prevents the expected atelectasis in the morbidly obese patients during general anaesthesia. Materials and Methods. 49 patients completed the examination and were randomized to 2 groups: ventilated without positive end-expiratory pressure (PEEP 0) and with PEEP of 10 cm H2O (PEEP 10) preceded by a recruitment maneuver with peak inspiratory pressure of 40 cm H2O. Impedance Ratio (IR) was utilized to examine ventilation distribution changes as a result of anaesthesia, pneumoperitoneum, and change of body position. We also analyzed intraoperative respiratory mechanics and pulse oximetry values. Results. In both groups general anaesthesia caused a ventilation shift towards the nondependent lungs which was not further intensified after pneumoperitoneum. Reverse Trendelenburg position promoted homogeneous ventilation distribution. Respiratory system compliance was reduced after insufflation and improved after exsufflation of pneumoperitoneum. There were no statistically significant differences in ventilation distribution between the examined groups. Respiratory system compliance, plateau pressure, and pulse oximetry values were higher in PEEP 10. Conclusions. Changes of ventilation distribution in the obese do occur at cranial lung regions. During pneumoperitoneum alterations of ventilation distribution may not follow the direction of the changes of lung mechanics. In the obese patients PEEP level of 10 cm H2O preceded by a recruitment maneuver improves respiratory compliance and oxygenation but does not eliminate atelectasis induced by general anaesthesia.

  14. Mechanical History Dependence in Carbon Black Suspensions for Flow Batteries: A Rheo-Impedance Study

    PubMed Central

    2017-01-01

    We studied the effects of shear and its history on suspensions of carbon black (CB) in lithium ion battery electrolyte via simultaneous rheometry and electrical impedance spectroscopy. Ketjen black (KB) suspensions showed shear thinning and rheopexy and exhibited a yield stress. Shear step experiments revealed a two time scale response. The immediate effect of decreasing the shear rate is an increase in both viscosity and electronic conductivity. In a much slower secondary response, both quantities change in the opposite direction, leading to a reversal of the initial change in the conductivity. Stepwise increases in the shear rate lead to similar responses in the opposite direction. This remarkable behavior is consistent with a picture in which agglomerating KB particles can stick directly on contact, forming open structures, and then slowly interpenetrate and densify. The fact that spherical CB particles show the opposite slow response suggests that the fractal structure of the KB primary units plays an important role. A theoretical scheme was used to analyze the shear and time-dependent viscosity and conductivity. Describing the agglomerates as effective hard spheres with a fractal architecture and using an effective medium approximation for the conductivity, we found the changes in the derived suspension structure to be in agreement with our qualitative mechanistic picture. This behavior of KB in flow has consequences for the properties of the gel network that is formed immediately after the cessation of shear: both the yield stress and the electronic conductivity increase with the previously applied shear rate. Our findings thus have clear implications for the operation and filling strategies of semisolid flow batteries. PMID:28122184

  15. Assessment of Ventilation Distribution during Laparoscopic Bariatric Surgery: An Electrical Impedance Tomography Study

    PubMed Central

    Gaszynski, Wojciech

    2016-01-01

    Introduction. The aim of the study was to assess changes of regional ventilation distribution at the level of the 3rd intercostal space in the lungs of morbidly obese patients as a result of general anaesthesia and laparoscopic surgery as well as the relation of these changes to lung mechanics. We also wanted to determine if positive end-expiratory pressure of 10 cm H2O prevents the expected atelectasis in the morbidly obese patients during general anaesthesia. Materials and Methods. 49 patients completed the examination and were randomized to 2 groups: ventilated without positive end-expiratory pressure (PEEP 0) and with PEEP of 10 cm H2O (PEEP 10) preceded by a recruitment maneuver with peak inspiratory pressure of 40 cm H2O. Impedance Ratio (IR) was utilized to examine ventilation distribution changes as a result of anaesthesia, pneumoperitoneum, and change of body position. We also analyzed intraoperative respiratory mechanics and pulse oximetry values. Results. In both groups general anaesthesia caused a ventilation shift towards the nondependent lungs which was not further intensified after pneumoperitoneum. Reverse Trendelenburg position promoted homogeneous ventilation distribution. Respiratory system compliance was reduced after insufflation and improved after exsufflation of pneumoperitoneum. There were no statistically significant differences in ventilation distribution between the examined groups. Respiratory system compliance, plateau pressure, and pulse oximetry values were higher in PEEP 10. Conclusions. Changes of ventilation distribution in the obese do occur at cranial lung regions. During pneumoperitoneum alterations of ventilation distribution may not follow the direction of the changes of lung mechanics. In the obese patients PEEP level of 10 cm H2O preceded by a recruitment maneuver improves respiratory compliance and oxygenation but does not eliminate atelectasis induced by general anaesthesia. PMID:28058262

  16. Spectroscopic study of molecular structure, antioxidant activity and biological effects of metal hydroxyflavonol complexes

    NASA Astrophysics Data System (ADS)

    Samsonowicz, Mariola; Regulska, Ewa

    2017-02-01

    Flavonols with varied hydroxyl substitution can act as strong antioxidants. Thanks to their ability to chelate metals as well as to donate hydrogen atoms they have capacity to scavenge free radicals. Their metal complexes are often more active in comparison with free ligands. They exhibit interesting biological properties, e.g. anticancer, antiphlogistic and antibacterial. The relationship between molecular structure and their biological properties was intensively studied using spectroscopic methods (UV-Vis, IR, Raman, NMR, ESI-MS). The aim of this paper is review on spectroscopic analyses of molecular structure and biological activity of hydroxyflavonol metal complexes.

  17. A study of high-impedance fault detection in distribution systems using a Kalman-filtering approach

    SciTech Connect

    Chang Wen Bin.

    1991-01-01

    Pitfalls associated with application of conventional filtering, fast fourier transform (FFT), and discrete Fourier transform (DFT) on signals with time-varying amplitude are first studied. These pitfalls are demonstrated by two numerical examples. The Kalman-filtering algorithm is then illustrated by examples to be well capable of tracking time-varying amplitude. The proposed high-impedance fault-detection scheme uses the Kalman-filtering algorithm for the optimal estimation of low-order harmonic components. A logic reasoning method is then applied to the estimated harmonic components for determining the possible cause of the disturbance. The performance of the detection scheme is evaluated by several staged arcing faults. A full investigation of these actual recorded arcing-fault data is also performed. Analysis results are used to justify the threshold values used in the proposed detection algorithm and to study the trends of variation of low-order harmonic components in the presence of a high-impedance fault.

  18. Spectroscopic Signatures and Structural Motifs of Dopamine: a Computational Study

    NASA Astrophysics Data System (ADS)

    Srivastava, Santosh Kumar; Singh, Vipin Bahadur

    2016-06-01

    Dopamine (DA) is an essential neurotransmitter in the central nervous system and it plays integral role in numerous brain functions including behaviour, cognition, emotion, working memory and associated learning. In the present work the conformational landscapes of neutral and protonated dopamine have been investigated in the gas phase and in aqueous solution by MP2 and DFT (M06-2X, ωB97X-D, B3LYP and B3LYP-D3) methods. Twenty lowest energy structures of neutral DA were subjected to geometry optimization and the gauche conformer, GIa, was found to be the lowest gas phase structure at the each level of theory in agreement with the experimental rotational spectroscopy. All folded gauche conformers (GI) where lone electron pair of the NH2 group is directed towards the π system of the aromatic ring ( 'non up' ) are found more stable in the gas phase. While in aqueous solution, all those gauche conformers (GII) where lone electron pair of the NH2 group is directed opposite from the π system of the aromatic ring ('up' structures) are stabilized significantly.Nine lowest energy structures, protonated at the amino group, are optimized at the same MP2/aug-cc-pVDZ level of theory. In the most stable gauche structures, g-1 and g+1, mainly electrostatic cation - π interaction is further stabilized by significant dispersion forces as predicted by the substantial differences between the DFT and dispersion corrected DFT-D3 calculations. In aqueous environment the intra-molecular cation- π distance in g-1 and g+1 isomers, slightly increases compared to the gas phase and the magnitude of the cation- π interaction is reduced relative to the gas phase, because solvation of the cation decreases its interaction energy with the π face of aromatic system. The IR intensity of the bound N-H+ stretching mode provides characteristic 'IR spectroscopic signatures' which can reflect the strength of cation- π interaction energy. The CC2 lowest lying S1 ( 1ππ* ) excited state of neutral

  19. 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.

  20. 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

  1. An impedance study of complex Al/Cu-Al2O3 electrode

    NASA Astrophysics Data System (ADS)

    Denisova, J.; Katkevics, J.; Erts, D.; Viksna, A.

    2011-06-01

    Electrochemical impedance spectroscopy (EIS) was used to investigate different Cu deposition regimes on Al surface obtained by internal electrolysis and to characterize properties of fabricated electrodes. EIS experimental data confirmed that Cu deposition by internal electrolysis is realized and the complex electrode system is obtained. The main difficulty in preparation of Al/Cu electrodes is to prevent aluminium oxidation before and during electrochemical deposition of Cu particles. In this work NaCl, CH3COONa, K2SO4, mono- and diammonium citrate electrolytes were examined to determine their suitability for impedance measurements. Al/Cu-Al2O3 electrode composition was approved by equivalent circuit analysis, optical and scanning electron microscope methods. The most optimal Cu deposition mode using internal electrolysis was determined. The obtained results are promising for future electrochemical fabrication of nanostructures directly on Al surfaces by internal electrolysis.

  2. 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.

  3. A study on calculation method for mechanical impedance of air spring

    NASA Astrophysics Data System (ADS)

    Changgeng, SHUAI; Penghui, LI; Rustighi, Emiliano

    2016-09-01

    This paper proposes an approximate analytic method of obtaining the mechanical impedance of air spring. The sound pressure distribution in cylindrical air spring is calculated based on the linear air wave theory. The influences of different boundary conditions on the acoustic pressure field distribution in cylindrical air spring are analysed. A 1-order ordinary differential matrix equation for the state vector of revolutionary shells under internal pressure is derived based on the non-moment theory of elastic thin shell. Referring to the transfer matrix method, a kind of expanded homogeneous capacity high precision integration method is introduced to solve the non-homogeneous matrix differential equation. Combined the solved stress field of shell with the calculated sound pressure field in air spring under the displacement harmonic excitation, the approximate analytical expression of the input and transfer mechanical impedance for the air spring can be achieved. The numerical simulation with the Comsol Multiphysics software verifies the correctness of theoretical analysis result.

  4. The accurate use of impedance analysis for the study of microbial electrochemical systems.

    PubMed

    Dominguez-Benetton, Xochitl; Sevda, Surajbhan; Vanbroekhoven, Karolien; Pant, Deepak

    2012-11-07

    The present critical review aims to portray the principles and theoretical foundations that have been used for the application of electrochemical impedance spectroscopy (EIS) to study electron-transfer mechanisms, mass transfer phenomena and distribution of the heterogeneous properties of microbial electrochemical systems (MXCs). Over the past eight years, the application of this method has allowed major breakthroughs, especially in the field of microbial fuel cells (MFCs); however, it is still most widely extended only to the calculation of internal resistances. The use and interpretation of EIS should greatly improve since the intrinsic knowledge of this field, and efforts and current trends in this field have already allowed its understanding based on rather meaningful physical properties and not only on fitting electrical analogues. From this perspective, the use, analysis and interpretation of EIS applied to the study of MXCs are critically examined. Together with the revision of more than 150 articles directly devoted to this topic, two examples of the correct and improved analysis of EIS data are extensively presented. The first one focuses on the use of graphical methods for improving EIS analysis and the other one concentrates on the elucidation of the constant phase element (CPE) parameters. CPEs have been introduced in equivalent circuit models, sometimes without solid justification or analysis; the effective capacitance has been obtained from CPE parameters, following an unsuitable theory for the case of microbial-electrochemical interfaces. The use of CPE is reviewed in terms of meaningful physical parameters, such as biofilm thickness. The use of a finite-diffusion element is reviewed throughout estimation of accurate values for obtaining the dimensionless numbers, Schmidt and Sherwood, in the context of a dioxygen-reducing-biocathode, under different flow-rate conditions. The use and analysis of EIS in this context are still emerging, but because of

  5. 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.

  6. 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.

  7. Impact of exacerbations on respiratory system impedance measured by a forced oscillation technique in COPD: a prospective observational study

    PubMed Central

    Kamada, Takahiro; Kaneko, Masahiro; Tomioka, Hiromi

    2017-01-01

    Background Forced oscillation technique (FOT) has been reported to be useful in the evaluation and management of obstructive lung disease, including COPD. To date, no data are available concerning long-term changes in respiratory system impedance measured by FOT. Additionally, although exacerbations have been reported to be associated with excessive lung function decline in COPD, the impact of exacerbations on the results of FOT has not been demonstrated. The aim of this study was to investigate the longitudinal changes in respiratory system impedance and the influence of exacerbations thereon. Methods Between March 2011 and March 2012, outpatients who attended Kobe City Medical Center West Hospital with a diagnosis of COPD were assessed for eligibility. Baseline patient characteristics (age, sex, body mass index, smoking history, current smoking status, COPD stage), lung function (post-bronchodilator forced expiratory volume in 1 second [FEV1]), blood tests (neutrophils and eosinophils), FOT, and COPD assessment test results were collected at enrollment. Lung function and FOT were examined every 6 months until March 2016. Annual changes in FEV1 and FOT parameters were obtained from the slope of the linear regression curve. The patients were divided into 2 groups based on exacerbation history. Results Fifty-one of 58 patients with COPD were enrolled in this study. The median follow-up period was 57 (52–59) months. Twenty-five (49%) patients experienced exacerbations. A significant annual decline in FEV1 and respiratory system impedance were shown. Additionally, annual changes in FEV1, respiratory system resistance at 5 Hz, respiratory system reactance at 5 Hz, and resonant frequency were greater in patients with exacerbations than in those without exacerbations. Conclusion Exacerbations of COPD lead not only to a decline in lung function but also to an increase in respiratory system impedance. PMID:28223791

  8. Study of Characterization of Pure and Malachite Green Doped Samples Using Spectroscopic Studies

    NASA Astrophysics Data System (ADS)

    Mishra, Jyoti; Mishra, Pankaj K.; Khare, P. K.

    2011-07-01

    This paper describes the results of SEM, EDX, UV-vis and TSDC study of malachite green doped PVK thermelectrets. TSDC study has been carried out in the temperature range 300 °C to 1500 °C with four different polarizing fields. One peak was observed at 110±10 °C which shifts toward high temperature with the increase in polarizing field. The activation energy found by initial rise method are 0.27±0.02 eV for pure and 0.40±0.03 eV for malachite green doped PVK thermoelectrets. Spectroscopic study concluded that impregnation of malachite green in polymer matrix forms charge transfer complexes.

  9. 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

    2005-08-05

    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.

  10. 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.

  11. Homogeneous superconducting phase in TiN film: A complex impedance study

    NASA Astrophysics Data System (ADS)

    Diener, P.; Schellevis, H.; Baselmans, J. J. A.

    2012-12-01

    The low frequency complex impedance of a high resistivity 92 μ Ω cm and 100 nm thick TiN superconducting film has been measured via the transmission of several high sensitivity GHz microresonators, down to TC/50. The temperature dependence of the kinetic inductance follows closely BCS local electrodynamics, with one well defined superconducting gap. This evidences the recovery of a homogeneous superconducting phase in TiN far from the disorder and composition driven transitions. Additionally, we observe a linearity between resonator quality factor and frequency temperature changes, which can be described by a two fluid model.

  12. In vivo localized proton spectroscopic studies of human gastrocnemius muscle

    SciTech Connect

    Narayana, P.A.; Jackson, E.F.; Hazle, J.D.; Fotedar, L.K.; Kulkarni, M.V.; Flamig, D.P.

    1988-10-01

    In vivo proton magnetic resonance spectroscopy studies of gastrocnemius muscle were performed in six normal volunteers. Both spatially resolved spectroscopy (SPARS) and stimulated echo acquisition mode (STEAM) sequences were used for volume localization. A number of water suppression sequences have been combined with these localization schemes. Among the various techniques investigated in these studies, STEAM with an inversion pulse (T1-discriminated spectrum) seems to have the best potential for in vivo localized high-resolution proton spectroscopy studies of human muscle.

  13. 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.

  14. 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.

  15. 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.

  16. 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...

  17. Conceptual design study to determine optimal enclosure vent configuration for the Maunakea Spectroscopic Explorer (MSE)

    NASA Astrophysics Data System (ADS)

    Szeto, Kei; Vogiatzis, Konstantinos; Hangan, Horia; Jubayer, Chowdhury M.; Breckenridge, Craig; Loewen, Nathan; Bauman, Steven; Salmon, Derrick

    2014-07-01

    The Maunakea Spectroscopic Explorer (MSE; formerly Next Generation Canada-France-Hawaii Telescope) is a dedicated, 10m aperture, wide-field, fiber-fed multi-object spectroscopic facility proposed as an upgrade to the existing Canada-France-Hawaii Telescope on the summit of Mauna Kea. The enclosure vent configuration design study is the last of three studies to examine the technical feasibility of the proposed MSE baseline concept. The enclosure vent configuration study compares the aero-thermal performance of three enclosure ventilation configurations based on the predicted dome thermal seeing and air flow attenuation over the enclosure aperture opening of a Calotte design derived from computational fluid dynamics simulations. In addition, functional and operation considerations such as access and servicing of the three ventilation configurations is discussed.

  18. Spectroscopic and theoretical study on alkali metal phenylacetates

    NASA Astrophysics Data System (ADS)

    Regulska, E.; Świsłocka, R.; Samsonowicz, M.; Lewandowski, W.

    2013-07-01

    The influence of lithium, sodium, potassium, rubidium and cesium cations on the electronic system of phenylacetic acid was studied. The FT-IR, FT-Raman and 1H and 13C NMR spectra were recorded for studied compounds. Characteristic shifts in IR and NMR spectra along alkali metal phenylacetates were observed. Good correlations between the wavenumbers of the vibrational bands in the IR spectra of phenylacetates and some alkali metal parameters such as ionic potential, electronegativity, inverse of atomic mass, atomic radius and ionization energy were found. The density functional hybrid method B3LYP with 6-311++G** basis set was used to calculate optimized geometrical structures of studied compounds. Aromaticity indices, atomic charges, dipole moments and energies were calculated as well as the wavenumbers and intensities of IR spectra and chemical shifts in NMR spectra. The theoretical parameters were compared to experimental characteristic of alkali metal phenylacetates.

  19. Spectroscopic and Raman excitation profile studies of 3-benzoylpyridine

    NASA Astrophysics Data System (ADS)

    Sett, Pinaky; Datta, Shirsendu; Chowdhury, Joydeep; Ghosh, Manash; Mallick, Prabal Kumar

    2017-03-01

    In the present work IR, UV absorption and Raman spectra including Raman excitation profiles and structure of 3-benzoyl pyridine have been investigated. Detailed studies on the vibrational and electronic properties of the molecule have been carried out. All these studies are aided with valuable quantum chemical calculations. The structural changes encountered on excitation to the low lying excited states have been investigated. Theoretical profiles determined by the sum-over-states method based on pertinent Franck-Condon and Herzberg-Teller terms have satisfactorily simulated the experimentally measured relative Raman intensities and these are also in compliance with the structural changes and potential energy distributions.

  20. Optical spectroscopic studies of heme proteins at high pressure

    SciTech Connect

    Swanson, B.I.; Agnew, S.F.; Ondrias, M.R.; Alden, R.G.

    1986-01-22

    There has been considerable interest in studying the physical and chemical behavior of small molecules at high static pressure by using diamond-anvil cells. In contrast to the relatively rich chemistry now developing on small molecules at high densities, studies of metalloproteins have largely been limited to relatively low pressures (<7 kbar) using UV-vis absorption, magnetic susceptibility, or NMR spectroscopy. Low-pressure studies of a variety of oxidized heme proteins have conclusively shown evidence for spin-state changes for the iron site at pressures above 1 kbar. Optical absorption studies of reduced heme proteins, while not conclusive, have also been interpreted in terms of spin-state changes. Other changes within the heme pocket most notably in the proximal histidine in the ..beta..-chain of Hb via proton NMR, have also been detected. The molecular bases for these changes and the behavior of the heme electronic states at higher pressures, however, remain open questions. In this paper both resonance Raman and absorption spectroscopy are used to address these problems in reduced heme proteins. Resonance Raman scattering is well suited for this application as it provides a structurally specific probe of the heme active site. 11 references, 2 figures.

  1. 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 ...

  2. 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.

  3. Green-synthesis, characterization, photostability and polarity studies of novel Schiff base dyes using spectroscopic methods.

    PubMed

    Marwani, Hadi M; Asiri, Abdullah M; Khan, Salman A

    2012-01-01

    Preparation, characterization, photostability and polarity studies of novel Schiff base dyes using spectroscopic methods were achieved. The Schiff base dyes were prepared by the reaction of salicylaldehyde/2-Hydroxy-1-naphthaldehyde with aminophenazone under microwave irradiation. The spectroscopic (FT-IR, 1H NMR, 13C-NMR, Mass) studies and elemental analyses were in good agreement with chemical structure of synthesized compounds. In addition, UV-Vis and fluorescence spectroscopic experiments showed that these dyes are good absorbent and fluorescent. Based on the photostability study of these dyes, minimal to no loss in fluorescence intensities of 4-[(2-Hydroxy-benzylidene)-amino] 1,5-dimethyl-2-phenyl-1,2-dihydro-pyrazol-3-one (D1) (6.14%) and 4-[(2-Hydroxy-naphthalen-1-ylmethylene)-amino]-1,5-dimethyl-2-phenyl-1,2-dihydro-pyrazol-3-one (D2) (2.95%) was observed with an increase in the exposure time using time-based fluorescence steady-state experiments. These studies also inferred that these Schiffbase dyes have a high photostability against photobleaching. In addition, Dye 2 is found to be more sensitive than Dye 1 to the polarity of the microenvironment provided by different solvents based on the results of fluorescence polarity studies.

  4. 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.

  5. Spectroscopic Studies of Metal-Ligand-Surface Interactions

    DTIC Science & Technology

    1988-10-01

    recent calculations by Bauschlicher. In this theoretical study the complexes’ bonding was attributed to an electrostatic interaction between the...section about the bonding mechanisms in the ammonia versus the hydrazine complexes. 3. Normal Coordinate Calculations on Metal.Ammonia Complexes To...and Benzene ...... o......46 III CALCULATIONS OF THE VIBRATIONAL SPECTRA OF N2 H4 ,’ ALL ITS DEUTERATED DERIVATIVES AND CH3 N2 13 . ........ oo.o

  6. 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.

  7. 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

  8. Mössbauer spectroscopic study of iron-chelate trammels

    NASA Astrophysics Data System (ADS)

    Pal, Sangita; Meena, S. S.; Ningthoujam, R. S.; Goswami, D.

    2014-04-01

    Any kind of waste effluent in the Indian context and other countries contains a lot of iron in any ore. During mining, milling, extraction and purification process iron acts as contaminant towards other metal's purity. It is essential to remove iron to the maximum extent. In this case, an "IN-HOUSE" resin polyacrylamidehydroxamic acid (PHOA) has been designed and developed which is highly hydrophilic three dimensionally cross-linked. It has an excellent iron binding capacity with almost no leaching. Interaction of resin with ammonium ferrous sulphate and red-mod (Fe2O3) is studied using Mössbauer spectroscopy.

  9. 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

  10. 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

    2015-10-05

    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.

  11. 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.

  12. 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.

  13. [Infrared spectroscopic study on leaf senescence of evergreen tree].

    PubMed

    Li, Lun; Zhou, Xiang-Ping; Liu, Gang; Zhang, Li; Ou, Quan-Hong; Hao, Jian-Ming

    2013-02-01

    In order to investigate plant physiological process of leaf senescence and aging, Fourier transform infrared (FTIR) spectroscopy was used to study the young, mature, and old yellow leaves from seven species of evergreen trees. The spectra of the leaves from different growing period are different in the region of 1 800-700 cm(-1). The absorption ratios A1 070/A2 927, A1 070/A1 160 were used to evaluate the relative changes of polysaccharides, and A1 318/A2 922 was used to estimate the change of calcium oxalate during leaf senescence. Decomposition and curve-fitting analysis was performed in the region of 1 800 -1 500 cm(-1). The sub-band absorption ratio H1 650/H1 740 was used to evaluate the relative changes of protein in the leaves. The results show that the accumulation and mobilization of polysaccharides, protein, and calcium oxalate during leaf growing period were different in different plant species. This study demonstrates the potential of mid-infrared spectroscopy for investigation of plants senescence, as well as physiological and biochemical changes of plants.

  14. Vibrational spectroscopic studies of Isoleucine by quantum chemical calculations.

    PubMed

    Moorthi, P P; Gunasekaran, S; Ramkumaar, G R

    2014-04-24

    In this work, we reported a combined experimental and theoretical study on molecular structure, vibrational spectra and NBO analysis of Isoleucine (2-Amino-3-methylpentanoic acid). The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments, thermodynamics properties, NBO analyses, NMR chemical shifts and ultraviolet-visible spectral interpretation of Isoleucine have been studied by performing MP2 and DFT/cc-pVDZ level of theory. The FTIR, FT-Raman spectra were recorded in the region 4000-400 cm(-1) and 3500-50 cm(-1) respectively. The UV-visible absorption spectra of the compound were recorded in the range of 200-800 nm. Computational calculations at MP2 and B3LYP level with basis set of cc-pVDZ is employed in complete assignments of Isoleucine molecule on the basis of the potential energy distribution (PED) of the vibrational modes, calculated using VEDA-4 program. The calculated wavenumbers are compared with the experimental values. The difference between the observed and calculated wavenumber values of most of the fundamentals is very small. (13)C and (1)H nuclear magnetic resonance chemical shifts of the molecule were calculated using the gauge independent atomic orbital (GIAO) method and compared with experimental results. The formation of hydrogen bond was investigated in terms of the charge density by the NBO calculations. Based on the UV spectra and TD-DFT calculations, the electronic structure and the assignments of the absorption bands were carried out. Besides, molecular electrostatic potential (MEP) were investigated using theoretical calculations.

  15. 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.

  16. Multinuclear nuclear magnetic resonance spectroscopic study of cartilage proteoglycans

    SciTech Connect

    Lerner, L.

    1985-01-01

    Hyaline cartilage is a composite material whose major function is to withstand compression while retaining flexibility. Its mechanical properties are affected by tissue hydration and ionic composition. Models of the mechanical behavior of cartilage have incorporated certain assumptions about the interactions of the major components of cartilage: collagen, proteoglycans, water, and cations. To determine the validity of these assumption, the authors have used nuclear magnetic resonance spectroscopy (NMR). Two approaches have been used: (a) natural abundance carbon-13 NMR; and (b) NMR of sodium-23, potassium-39, magnesium-25, and calcium-43. Evidence from studies in intact tissues are reinforced by extensive measurements on solutions of proteoglycans and other relevant macromolecules. Based on the measurements of NMR relaxation rates and lineshapes reported here, it is concluded that neither sodium nor potassium interact strongly with bovine nasal proteoglycan aggregates or their substituent glycosaminoglycan chains in solution. Proteoglycans do bind magnesium and calcium. Therefore there is a qualitative difference between monovalent and divalent cations, which is not taken into account by polyelectrolyte models or models for the ionic dependence of mechanical properties. Cation binding to heparin, which has a higher charge density than cartilage proteoglycans, was also studied. The results presented here establish that heparin binds sodium, magnesium, and calcium.

  17. 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.

  18. 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.

  19. Theoretical spectroscopic study of protonated and deuteronated PAHs

    NASA Astrophysics Data System (ADS)

    Buragohain, Mridusmita; Pathak, Amit

    The study of Polycyclic Aromatic Hydrocarbon (PAH) plays a key role to understand astrophysical environments as they are ubiquitous in the Interstellar Medium (ISM). They account for about 5-10% of carbon budget in the universe and are responsible for the strong IR emission features at 3.3, 6.2, 7.7, 8.6, 11.2 and 12.7mum seen towards most of the interstellar objects including HII regions, reflection nebulae, planetary nebulae, late-type stars, as well as active star-forming regions. These IR features result from the relaxation of vibrationally excited PAHs. As PAHs are stable enough to survive the interstellar conditions, they could possibly be responsible for the enigmatic Diffuse Interstellar Bands (DIBs) which are optical absorption features on the interstellar extinction curve. The fact that interstellar PAHs are more likely to be ions has motivated the study of radical PAHs. Protonated PAHs formed by H(+) addition to neutral parent molecules, denoted as HPAH(+) , are an important form of closed shell PAH cation. Protonated forms show electronic transitions in the visible part of the spectrum where most DIBs are present, whereas neutral forms generally show their strongest electronic transitions in the UV region. We also report quantum chemical calculations on HPAH(+) and DPAH(+) (D(+) attached to PAH) to get the electronic and IR spectra to understand the IR emission and DIB features. A comparison of theoretical spectra with the available experimental spectra has also been carried out.

  20. Kinetic and Spectroscopic Studies of Heterogeneous Catalytic Reactions

    NASA Astrophysics Data System (ADS)

    Wilke, Todd E.

    1990-01-01

    The selective oxidation of ethylene was studied on a high surface area colloidal silver catalyst. In 0.1 to 1 torr of 20% ethylene in oxygen, the catalyst produced ethylene oxide with a selectivity of 20 to 30% at temperatures between 473 and 573 K. Surface-enhanced Raman (SER) spectra exhibited a distinct feature at 995 cm^ {-1}. This band was also observed for catalysts exposed to just oxygen, and it shifted to 980 cm^{-1} after heating the catalyst to 873 K in ^{18} O_2. No isotopic shift was observed with ^{18}O _2 at temperatures below 573 K. Similar spectral results were obtained at atmospheric pressure. For silver catalysts that contain adsorbed chlorine, SER bands were observed at 240, 1015, and 1045 cm^ {-1} in oxygen-containing atmospheres; the 995 cm^{-1} band was not evident. The extension of SERS to other metals that do not exhibit the surface-enhanced effect was examined by electrodepositing thin layers (2 to 3 monolayers) of platinum, rhodium, and ruthenium on a roughened gold substrate. At atmospheric pressure and temperatures between 298 and 473 K, metal-oxygen features were observed at 500 cm ^{-1}, and 490 and 600 cm ^{-1} in SER spectra of rhodium and ruthenium surfaces exposed to oxygen, respectively. Bands attributed to adsorbed carbon monoxide were observed in SER spectra of platinum (470, 2060, 390, and 1890 cm ^{-1}) and rhodium (465 and 2040 cm^{-1}) surfaces exposed to carbon monoxide and oxygen mixtures. The temporal replacement of adsorbed carbon monoxide by nitric oxide as well as temperature-induced changes in the surface composition were studied on a seconds timescale with a spectrograph -charge coupled device detector arrangement. The adsorption and oxidation of sulfur dioxide was also studied. A band assigned to the S-O stretch of molecularly adsorbed sulfur dioxide was observed at 1130 cm^{-1} on unmodified gold and platinum-coated gold surfaces exposed to sulfur dioxide at 298 K. Dissociative chemisorption of sulfur dioxide on

  1. Negative ion photoelectron spectroscopic studies of transition metal cluster

    NASA Astrophysics Data System (ADS)

    Marcy, Timothy Paul

    The studies reported in this thesis were performed using a negative ion photoelectron spectrometer consisting of a cold cathode DC discharge ion source, a flowing afterglow ion-molecule reactor, a magnetic sector mass analyzer, an argon ion laser for photodetachment and a hemispherical electron kinetic energy analyzer and microchannel plate detector for photoelectron spectrum generation. The 476.5 nm (2.601 eV), 488.0 nm (2.540 eV) and 514.5 nm (2.410 eV) negative ion photoelectron spectra of VMn are reported and compared to the previously studied spectra of isoelectronic Cr2.1 The photoelectron spectra are remarkably similar to those of Cr2 in electron affinity and vibrational frequencies. The 488.0 nm photoelectron spectra and electron affinities of Nb n- (n = 1 - 9) are reported with discussion of observed vibrational structure. There are transitions to several electronic states of Nb2 in the reported spectra with overlapping vibrational progressions. The spectra of Nb3, Nb4 and Nb6 show partially resolved vibrational structure in the transitions to the lowest observed electronic state of each cluster. There is a single distinct active vibrational mode in the transition to the ground state of Nb8. Spin-orbit energies of Nb- are also reported. The 488.0 nm negative ion photoelectron spectra of Nb3H(D) are reported and compared to those of Nb3. There is a single vibrational mode active in the spectra of Nb3H(D) which is very similar to the most distinct mode active in the spectrum of Nb3. The 488.0 nm photoelectron spectra of the NbxCyH(D) y- (x = 1, 2, 3, y = 2, 4, 6) dehydrogenated products of the reactions of ethylene with niobium cluster anions are reported. Temperature studies of some of these species give evidence for the presence of multiple isomers of each molecule in the ion beam. The spectra of NbC6H(D) 6 are identical to those obtained from the reactions of benzene with niobium clusters and indicate that benzene is being formed from ethylene in the flow

  2. Identification and derivatization of selected cathinones by spectroscopic studies.

    PubMed

    Nycz, Jacek E; Pazdziorek, Tadeusz; Malecki, Grzegorz; Szala, Marcin

    2016-09-01

    In this study we identified three novel hydrochloride salts of cathinones 2-(pyrrolidin-1-yl)-1-(5,6,7,8-tetrahydronaphthalen-2-yl)pentan-1-one (1a) (TH-PVP), 2-(methylamino)-1-(2-methylphenyl)-1-propanone (1b) (2-MMC) and 1-(4-chlorophenyl)-2-(methylamino)propan-1-one (1c) (4-CMC). Their properties have been examined through combinations of GC-MS, IR, NMR, electronic absorption spectroscopy and single crystal X-ray diffraction method. NMR solution spectra showed readily diagnostic H-1 and C-13 signals from methyl, N-methyl and carbonyl groups. Additionally the use of thionation and amination reactions for identification of selected cathinones was presented.

  3. Spectroscopic Study of Sediments from Chapala Lake in Western Mexico

    NASA Astrophysics Data System (ADS)

    Arízaga, G. G. Carbajal; Doumer, M. E.; Lucio, G. Álvarez; Salazar, S. Gómez; Mangrich, A. S.; Huerta, A. García

    2016-11-01

    The first 10 cm of sediment from Lake Chapala, Western Mexico are in constant activity related to the exchange and speciation of metal cations. Samples of this sediment were analyzed in electron paramagnetic resonance (EPR) equipment to study the paramagnetic metals. Assays indicated that only Fe3+ was present in a detectable amount. This cation, along with chemical fractions of sediment obtained by sequential extraction, was analyzed by EPR. The analysis supported by infrared data revealed that Fe3+ was present in diluted and concentrated domains. Easily exchangeable iron was retained by carbonyl groups in organic matter. The carbonate fraction and oxides contained iron in concentrated domains. The alumina-silicate fraction (that resisted the sequential extraction digestions) presented diluted domains of iron in the octahedral alumina sheet along with occlusions of concentrated domains. This last inference was obtained by comparing EPR results against the spectrum of iron in synthetic model clay.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. [Spectroscopic studies of guanidine hydrochloride-induced unfolding of hemoglobin].

    PubMed

    Li, Jin-Jing; Tang, Qian; Cao, Hong-Yu; Zhang, Yu-Jiao; Zhang, Tao; Zheng, Xue-Fang

    2012-09-01

    In the present paper, based on the ultraviolet-visible (UV-Vis) absorption spectroscopy, fluorescence spectroscopy, and stopped flow-fluorescence spectroscopy, the authors studied the protein unfolding process of hemoglobin induced by GdmHcl. The experiments result shows that there were two different procedures about GdmHcl inducing hemoglobin unfolding from the evidences of UV-Vis absorption spectrum and fluorescence phase diagrams. Namely, the hemoglobin subunit exhibits depolymerization, forming the intermediates when incubated with GdmHcl at the concentration of 1. 0 mol x L(-1). With the increase in the concentration, various subunit structure became loose gradually, and the protoheme collapsed eventually. UV-Vis absorption spectroscopy indicates that the addition of reductant can cooperate with the depolymerization of hemoglobin subunit and the disaggregation of protoheme. The reductant results in the unfolding procedure that hemoglobin from "three-state model" turns into "two-state model".

  9. Spectroscopic STM studies of single gold(III) porphyrin molecules.

    PubMed

    Müllegger, Stefan; Schöfberger, Wolfgang; Rashidi, Mohammad; Reith, Lorenz M; Koch, Reinhold

    2009-12-16

    Low-temperature scanning tunneling microscopy, a well-established technique for single-molecule investigations in an ultrahigh vacuum environment, has been used to study the electronic properties of Au(III) 5,10,15,20-tetraphenylporphyrin (AuTPP) molecules on Au(111) at the submolecular scale. AuTPP serves as a model system for chemotherapeutically relevant Au(III) porphyrins. For the first time, real-space images and local scanning tunneling spectroscopy data of the frontier molecular orbitals of AuTPP are presented. A comparison with results from density functional theory reveals significant deviations from gas-phase behavior due to a non-negligible molecule/substrate interaction. We identify the oxidation state of the central metal ion in the adsorbed AuTPP as Au(3+).

  10. A spectroscopic study of the blue stragglers in M67

    NASA Astrophysics Data System (ADS)

    Liu, G. Q.; Deng, L.; Chávez, M.; Bertone, E.; Davo, A. Herrero; Mata-Chávez, M. D.

    2008-10-01

    Based on spectrophotometric observations from the Guillermo Haro Observatory (Cananea, Mexico), a study of the spectral properties of the complete sample of 24 blue straggler stars (BSs) in the old Galactic open cluster M67 (NGC 2682) is presented. All spectra, calibrated using spectral standards, were recalibrated by means of photometric magnitudes in the Beijing-Arizona-Taipei-Connecticut system, which includes fluxes in 11 bands covering ~3500-10000 Å. The set of parameters was obtained using two complementary approaches that rely on a comparison of the spectra with (i) an empirical sample of stars with well-established spectral types and (ii) a theoretical grid of optical spectra computed at both low and high resolution. The overall results indicate that the BSs in M67 span a wide range in Teff(~ 5600 -12600 K) and surface gravities that are fully compatible with those expected for main-sequence objects (log g = 3.5 -5.0 dex).

  11. 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.

  12. Computational and vibrational spectroscopic studies of ipratropium bromide.

    PubMed

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

    2009-02-01

    In this study, ipratropium bromide is investigated using vibrational spectroscopy and quantum chemical calculations. The structure of ipratropium bromide was optimised using density functional theory calculations and the geometry optimisation has been carried out on two conformations with and without intramolecular hydrogen bonding. Infrared and Raman spectra were calculated from the optimised structures. Many modes in the calculated spectra could be matched with the experimental spectra and a description of the modes is given. By analysis of the theoretical vibrational modes, it is shown that ipratropium bromide specimens are likely to be a mixture of the two conformations with and without intramolecular hydrogen bonding. In addition, several spectral features and band intensities in the CH and OH stretching regions are explained. Quantum mechanical calculations allowed improved understanding of ipratropium bromide and its vibrational spectra.

  13. Conformational analysis and vibrational spectroscopic studies on dapsone

    NASA Astrophysics Data System (ADS)

    Ildiz, Gulce Ogruc; Akyuz, Sevim

    2012-11-01

    In this study, the theoretical conformation analysis of free dapsone has been performed by single point energy calculations at both semi-empirical PM3 and DFT/B3LYP-3-21G theory levels and three stable conformers were determined. Both the IR and Raman spectra of the molecule in solid phase have been recorded. The IR intensities and harmonic vibrational wavenumbers of each conformer were calculated by DFT method at B3LYP/6-31++G(d,p) theory level. For the fundamental characterization, the total energy distribution (TED) calculations of the vibrational modes were done using parallel quantum mechanic solution program (SQM) and the fundamental modes were assigned. The theoretical results are in agreement with the experimental ones.

  14. 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.

  15. FTIR Spectroscopic Studies on Cross Linking of SU-8 Photoresist

    NASA Astrophysics Data System (ADS)

    Kalaiselvi, S. M. P.; Tan, T. L.; Rawat, R. S.; Lee, P.; Heussler, S. P.; Breese, M. B. H.

    2013-11-01

    The usage of chemically-amplified, negative tone SU-8 photoresist is numerous, spanning industrial, scientific and medical fields. Hence, in this study, some preliminary studies were conducted to understand the dosage and heat treatment requirements of the SU-8 photoresist essential for pattern generation using X-ray lithography. In this work, using Synchrotron as the X-ray source, SU-8 photoresist was characterized for X-ray lithography in terms of its process parameters such as X-ray exposure dose, post exposure bake (PEB) time and temperature for various photoresist thicknesses which is considered worthwhile in view of applications of SU-8 for the fabrication of very high aspect ratio micro structures. The process parameters were varied and the resultant cross linking of the molecular chains of the photoresist was accurately monitored using a Fourier Transform Infra-Red (FTIR) spectrometer and the results are discussed. The infrared absorption peak at 914 cm-1 in the spectrum of the SU-8 photoresist was found to be a useful indicator for the completion of cross linking in the SU-8 photoresist. Results show that the cross linking of the SU-8 photoresist is at a higher rate from 0 J/cm3 to 30 J/cm3 after which the peak almost saturates regardless of the PEB time. It is a good evidence for the validation of dosage requirement of SU-8 photoresist for effective completion of cross linking, which in turn is a requirement for efficient fabrication of micro and nano structures. An analogous behavior was also observed between the extent of cross linking and the PEB time and temperature. The rate of cross linking declines after a certain period of PEB time regardless of PEB temperature. The obtained results also show a definite relation between variation of the absorbance area of the peak at 914 cm-1 and the X-ray exposure dose.

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

    NASA Astrophysics Data System (ADS)

    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 (Al 2Si 2O 5(OH) 5), illite (KAl 4(Si 7AlO 20)(OH) 4), feldspar (K- and NaAlSi 3O 8), quartz (α-SiO 2), hematite (α-Fe 2O 3), montmorillonite (Mg 3(Si,Al) 4(OH) 2·4.5H 2O[Mg] 0.35), and calcium silicate (CaSiO 3). Gypsum (CaSO 4·2H 2O) and calcium carbonates (most likely calcite, CaCO 3) 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 (CaSO 4). 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 °C, which suggests the use of open fire. The reddish brown and grayish black colours were likely due to hematite and amorphous carbon, respectively.

  17. 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.

  18. 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.

  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.

  20. A study on transmission characteristics and specific absorption rate using impedance-matched electrodes for various human body communication.

    PubMed

    Machida, Yuta; Yamamoto, Takahiko; Koshiji, Kohji

    2013-01-01

    Human body communication (HBC) is a new communication technology that has presented potential applications in health care and elderly support systems in recent years. In this study, which is focused on a wearable transmitter and receiver for HBC in a body area network (BAN), we performed electromagnetic field analysis and simulation using the finite difference time domain (FDTD) method with various models of the human body. Further we redesigned a number of impedance-matched electrodes to allow transmission without stubs or transformers. The specific absorption rate (SAR) and transmission characteristics S21 of these electrode structures were compared for several models.

  1. Spectroscopic study of intermolecular complexes between FAD and some β-carboline derivatives

    NASA Astrophysics Data System (ADS)

    Codoñer, Armando; Monzó, Isidro S.; Tomás, Francisco; Valero, Rosa

    The formation of molecular complexes between flavine adenine dinucleotide (FAD) and some β-carboline derivatives [antidepressant drugs that have a pronounced inhibition of monoamine oxidase (MAO)] has been studied by using electronic absorption and fluorescence spectroscopic methods. Thermodynamic parameters have been determined from the values of association constants for the molecular complexes at various temperatures. The influence of substituents in the β-carboline molecule on the stability of the complexes formed was also investigated.

  2. AC Impedance Studies on Metal/Nanoporous Silicon/ p-Silicon Structures

    NASA Astrophysics Data System (ADS)

    Mabrook, M. F.; Ray, A. K.

    2017-04-01

    Alternating current (AC) impedance measurements have been performed on 10- to 15- μm thick porous silicon layers on a (100) p-type silicon ( p(+)Si) substrate with the aluminium (Al) top electrode in a sandwich configuration in the range of 20 Hz-1 MHz and in the temperature ranging between 152 K and 292 K. The ac conductivity σ ac was found to increase with frequency f according to the universal power law: σ_{{ac}} = Afs where the exponent s is a frequency and temperature-dependent quantity. A hopping process is found to be dominant at low temperatures and high frequencies, while a thermally activated free band process is responsible for conduction at higher temperatures. Capacitance is found to decrease with frequency but increase with temperature. Frequency dependence of the loss tangent is observed with a temperature-dependent minimum value.

  3. Electrochemical characteristics and impedance spectroscopy studies of nano-cobalt silicate hydroxide for supercapacitor

    NASA Astrophysics Data System (ADS)

    Zhang, Guo-Qing; Zhao, Yong-Qing; Tao, Feng; Li, Hu-Lin

    Cobalt silicate hydroxide (Co 3[Si 2O 5] 2[OH] 2) was prepared by chemical method for use in electrochemical capacitors. X-ray diffraction (XRD) and transmission electron microscopy (TEM) tests indicate that the material was pure hexagonal phase with uniform nanometer size distribution. Cyclic voltammeter (CV) and galvanostatic charge/discharge measurements show that the cobalt silicate hydroxide-based electrode has stable electrochemical capacitor properties between potential range of 0.1-0.55 V with a maximum specific capacitance of 237 F g -1 in alkaline solution and 95% of capacity efficiency was reached after 150 cycles. Electrochemical impedance spectra (EIS) investigation illustrates that the capacitance of the test electrode was mainly consisted of pseudo-capacitance, which was caused by underpotential deposition of H 3O + at the electrode surface.

  4. Impedance spectroscopy study on graphene wrapped nanocrystalline V2O5

    NASA Astrophysics Data System (ADS)

    Bhaskaram, D. Surya; Govindaraj, G.; Cheruku, Rajesh

    2016-05-01

    Nanocrystalline V2O5 was synthesized by solvothermal technique, which has potential application as electrode material in supercapacitors. The graphene oxide (GO) was prepared by modified Hummer's method. The V2O5/ reduced graphene oxide (RGO) composite was synthesized using surfactant free hydrothermal technique to enhance the functionality in terms of conductivity and surface area of V2O5. The structural characterization was accomplished through X-ray diffraction and Raman spectroscopy. Morphology was identified by SEM and surface area of VRGO was enhanced by 8 times in comparison with V2O5 nano particles, as confirmed through BET surface area analysis. Electrical characterization was done through impedance spectroscopy and the results showed decrease in sample resistance after wrapping V2O5 with RGO.

  5. Studies on the electrochemical impedance spectroscopy of Zr-based Laves phase metal hydride electrodes

    SciTech Connect

    Chen, J.; Dou, S.X.; Bradhurst, D.; Liu, H.K.

    1997-12-01

    The impedance spectra of Zr(V{sub 0.4}Ni{sub 0.6}){sub 2}, Zr(V{sub 0.2}Mn{sub 0.2}Ni{sub 0.6}){sub 2}, Zr(V{sub 0.2}Mn{sub 0.2}Ni{sub 0.55}Si{sub 0.05}){sub 2} alloys have been investigated. An equivalent circuit for the reaction of an MH electrode is proposed. The results reveal that: (1) the additions of Mn and Si have significant effects on the reaction resistances of the alloys; (2) Ni powder is an appropriate additive material in the manufacturing process of an MH electrode; (3) the amounts of Ni powder in the alloy electrode also should be considered in the practical utilization.

  6. AC Impedance Studies on Metal/Nanoporous Silicon/p-Silicon Structures

    NASA Astrophysics Data System (ADS)

    Mabrook, M. F.; Ray, A. K.

    2016-11-01

    Alternating current (AC) impedance measurements have been performed on 10- to 15-μm thick porous silicon layers on a (100) p-type silicon (p(+)Si) substrate with the aluminium (Al) top electrode in a sandwich configuration in the range of 20 Hz-1 MHz and in the temperature ranging between 152 K and 292 K. The ac conductivity σ ac was found to increase with frequency f according to the universal power law: σ_{ac} = Afs where the exponent s is a frequency and temperature-dependent quantity. A hopping process is found to be dominant at low temperatures and high frequencies, while a thermally activated free band process is responsible for conduction at higher temperatures. Capacitance is found to decrease with frequency but increase with temperature. Frequency dependence of the loss tangent is observed with a temperature-dependent minimum value.

  7. Impedance Spectroscopy as a Tool for the Electrochemical Study of Mixed Conducting Ceria

    NASA Astrophysics Data System (ADS)

    Lai, Wei

    2007-10-01

    The A.C. impedance response of mixed ionic and electronic conductors (MIECs) is derived from first principles and quantitatively compared with experimental data of three model systems: pO2 |Pt|Sm0.15Ce0.85O2--delta(1350°C)|Pt| pO2 (system I), pO2 |Pt|Sm0.15Ce0.85O2--delta(1550°C|Pt| pO2 (system II), and pO2 (c)|Ba0.5Sr0.5Co0.8Fe 0.2O3--delta|Sm0.15Ce0.85O 2--delta(1350°C)|Pt| pO2 (a) (system III). For the equilibrium systems I and II, which differ in terms of the preparation of the electrolyte, a broad spectrum of electrical and thermodynamic properties is extracted solely from the measurement of impedance spectra over wide oxygen partial pressure (10--31--0.21 atm) and temperature ranges (500 to 650°C). Electrolyte parameters derived from quantitative fitting of the impedance spectra include the concentration of free electron carriers, the mobilities for both ion and electron transport, the entropy and enthalpy of reduction of Ce4+ to Ce3+, and, for system II, the space charge potential characterizing the grain boundary behavior. In addition, the electrochemical behavior of O2 and H2 at the Pt|ceria interface has been characterized from these measurements. Under oxidizing conditions, the data suggest an oxygen electro-reduction reaction that is rate limited by the dissociated adsorption/discussion of oxygen species on the Pt electrode, similar to Pt|zirconia. Under reducing conditions, the inverse of the electrode polarization resistivity obeys a p-1/4O2 dependence, with an activation energy that is similar to that measured for the electronic conductivity. These results suggest that ceria is electrochemically active for hydrogen electro-oxidation and that the reaction is limited by the rate of removal of electrons from the ceria surface. For the nonequilibrium system III, examined from 550 to 650°C, the cathode oxygen partial pressure was fixed at 0.21 atm and the anode H2 was varied from 0.2 to 1 atm. The combination of Open Circuit Voltage (OCV) measurement

  8. 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.

  9. Ir Spectroscopic Studies on Microsolvation of HCl by Water

    NASA Astrophysics Data System (ADS)

    Mani, Devendra; Schwan, Raffael; Fischer, Theo; Dey, Arghya; Kaufmann, Matin; Redlich, Britta; van der Meer, Lex; Schwaab, Gerhard; Havenith, Martina

    2016-06-01

    Acid dissociation reactions are at the heart of chemistry. These reactions are well understood at the macroscopic level. However, a microscopic level understanding is still in the early stages of development. Questions such as 'how many H_2O molecules are needed to dissociate one HCl molecule?' have been posed and explored both theoretically and experimentally.1-5 Most of the theoretical calculations predict that four H_2O molecules are sufficient to dissociate one HCl molecule, resulting in the formation of a solvent separated H_3O+(H_2O)3Cl- cluster.1-3 IR spectroscopy in helium nanodroplets has earlier been used to study this dissociation process.3-5 However, these studies were carried out in the region of O-H and H-Cl stretch, which is dominated by the spectral features of undissociated (HCl)m-(H_2O)n clusters. This contributed to the ambiguity in assigning the spectral features arising from the dissociated cluster.4,5 Recent predictions from Bowman's group, suggest the presence of a broad spectral feature (1300-1360 wn) for the H_3O+(H_2O)3Cl- cluster, corresponding to the umbrella motion of H_3O+ moiety.6 This region is expected to be free from the spectral features due to the undissociated clusters. In conjunction with the FELIX laboratory, we have performed experiments on the (HCl)m(H_2O)n (m=1-2, n≥4) clusters, aggregated in helium nanodroplets, in the 900-1700 wn region. Mass selective measurements on these clusters revealed the presence of a weak-broad feature which spans between 1000-1450 wn and depends on both HCl as well as H_2O concentration. Measurements are in progress for the different deuterated species. The details will be presented in the talk. References: 1) C.T. Lee et al., J. Chem. Phys., 104, 7081 (1996). 2) H. Forbert et al., J. Am. Chem. Soc., 133, 4062 (2011). 3) A. Gutberlet et al., Science, 324, 1545 (2009). 4) S. D. Flynn et al., J. Phys. Chem. Lett., 1, 2233 (2010). 5) M. Letzner et al., J. Chem. Phys., 139, 154304 (2013). 6) J. M

  10. Transport in fuel cells: Electrochemical impedance spectroscopy and neutron imaging studies

    NASA Astrophysics Data System (ADS)

    Aaron, Douglas Scott

    This dissertation focuses on two powerful methods of performing in-situ studies of transport limitations in fuel cells. The first is electrochemical impedance spectroscopy (EIS) while the second is neutron imaging. Three fuel cell systems are studied in this work: polymer electrolyte membrane fuel cells (PEMFCs), microbial fuel cells (MFCs) and enzyme fuel cells (EFCs). The first experimental section of this dissertation focuses on application of EIS and neutron imaging to an operating PEMFC. The effects of cathode-side humidity and flow rate, as well as cell temperature and a transient response to cathode-side humidity, were studied for a PEMFC via EIS. It was found that increased air humidity in the cathode resulted in greatly reduced cathode resistance as well as a significant reduction in membrane resistance. The anode resistance was only slightly reduced in this case. Increased air flow rate was observed to have little effect on any resistance in the PEMFC, though slight reductions in both the anode and the cathode were observed. Increased cell temperature resulted in decreased cathode and anode resistances. Finally, the transient response to increased humidity exhibited unstable behavior for both the anode and the cathode resistances and the PEMFC power output. Neutron imaging allowed the calculation of water content throughout the PEMFC, showing a maximum in water content at the cathode gas diffusion layer - membrane interface. The second experimental section of this dissertation delves into the world of microbial fuel cells. Multiple long-term observations of changes in internal resistances were performed and illustrated the reduction in anode resistance as the bacterial community was established. Over this same time period, the cathode resistance was observed to have increased; these two phenomena suggest that the anode improved over time while the cathode suffered from degradation. Increased anode fluid ionic strength and flow rate both led to significant

  11. 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.

  12. A spectroscopic study of the open cluster NGC 6250

    NASA Astrophysics Data System (ADS)

    Martin, A. J.; Stift, M. J.; Fossati, L.; Bagnulo, S.; Scalia, C.; Leone, F.; Smalley, B.

    2017-04-01

    We present the chemical abundance analysis of 19 upper main-sequence stars of the young open cluster NGC 6250 (log t ∼ 7.42 yr). This work is part of a project aimed at setting observational constraints on the theory of atomic diffusion in stellar photospheres, by means of a systematic study of the abundances of the chemical elements of early F-, A- and late B-type stars of well-determined age. Our data set consists of low-, medium- and high-resolution spectra obtained with the Fibre Large Array Multi Element Spectrograph (FLAMES) instrument of the ESO Very Large Telescope (VLT). To perform our analysis, we have developed a new suite of software tools for the chemical abundance analysis of stellar photospheres in local thermodynamical equilibrium. Together with the chemical composition of the stellar photospheres, we have provided new estimates of the cluster mean radial velocity, proper motion, refined the cluster membership, and we have given the stellar parameters including masses and fractional age. We find no evidence of statistically significant correlation between any of the parameters, including abundance and cluster age, except perhaps for an increase in Ba abundance with cluster age. We have proven that our new software tool may be successfully used for the chemical abundance analysis of large data sets of stellar spectra.

  13. A theoretical and spectroscopic study of conformational structures of piroxicam

    NASA Astrophysics Data System (ADS)

    Souza, Kely Ferreira de; Martins, José A.; Pessine, Francisco B. T.; Custodio, Rogério

    2010-02-01

    Piroxicam (PRX) has been widely studied in an attempt to elucidate the causes and mechanisms of its side effects, mainly the photo-toxicity. In this paper fluorescence spectra in non-protic solvents and different polarities were carried out along with theoretical calculations. Preliminary potential surfaces of the keto and enol forms were obtained at AM1 level of theory providing the most stable conformers, which had their structure re-optimized through the B3LYP/CEP-31G(d,p) method. From the optimized structures, the electronic spectra were calculated using the TD-DFT method in vacuum and including the solvent effect through the PCM method and a single water molecule near PRX. A new potential surface was constructed to the enol tautomer at DFT level and the most stable conformers were submitted to the QST2 calculations. The experimental data showed that in apolar media, the solution fluorescence is raised. Based on conformational analysis for the two tautomers, keto and enol, the results indicated that the PRX-enol is the main tautomer related to the drug fluorescence, which is reinforced by the spectra results, as well as the interconvertion barrier obtained from the QST2 calculations. The results suggest that the PRX one of the enol conformers presents great possibility of involvement in the photo-toxicity mechanisms.

  14. Luminescence and spectroscopic studies of halosulfate phosphors: a review.

    PubMed

    Gedam, S C; Thakre, P S; Dhoble, S J

    2015-03-01

    This review discusses the photoluminescence (PL) characteristics of halosulfate phosphors developed by us. Halosulfate phosphors KCaSO4 Cl:X,Y (X = Eu or Ce; Y = Dy or Mn) and Na6 (SO4 )2 FCl (doped with Dy, Ce or Eu) were prepared using a solid-state diffusion method. The mechanism of energy transfer from Eu(2+) →Dy(3+) , Ce(3+) →Dy(3+) and Ce(3+) →Mn(2+) has also been studied. Dy(3+) emission in the host at 475 and 570 nm is observed due to (4) F9/2 →(6) H15/2 and (4) F9/2 →(6) H13/2 transition, whereas the PL emission spectra of Na6 (SO4 )2 FCl:Ce phosphor shows Ce(3+) emission at 322 nm due to 5d→4f transition of the Ce(3+) ion. The main property of KCaSO4 Cl is its very high sensitivity, particularly when doped by Dy, Mn or Pb activators. This review also discusses the PL characteristics of some new phosphors such as LiMgSO4 F, Na6 Pb4 (SO4 )6 Cl2 , Na21 Mg(SO4 )10 Cl3 and Na15 (SO4 )5 F4 Cl.

  15. Spectroscopic studies of aluminosilicate formation in tank waste simulants

    SciTech Connect

    Su, Y.; Wang, L.; Bunker, B.C.; Windisch, C.F.

    1997-12-31

    Aluminosilicates are one of the major class of species controlling the volume of radioactive high-level waste that will be produced from future remediation at Hanford site. Here the authors present studies of the phases and structures of aluminosilicates as a function of sludge composition using X-ray powder diffraction, solid state {sup 27}Al and {sup 29}Si NMR, and Raman spectroscopy. The results show that the content of NaNO{sub 3} in solution has significant effects on the nature of the insoluble aluminosilicate phases produced. It was found that regardless of the initial Si:Al ratio, nitrate cancrinite was the main phase formed in the solution with pH of 13.5 and 5 M NaNO{sub 3}. However, at lower NaNO{sub 3} concentration with initial Si:Al ratios of 1.1, 2.2, and 11.0 in the solutions, a range of aluminosilicate zeolites was produced with Si:Al ratios of 1.1, 1.3, and 1.5, respectively. Lowering the solution pH appears to promote the formation of amorphous aluminosilicates. The results presented here are important for the prediction of the solubility and dissolution rate of Al in tank wastes.

  16. [The IR spectroscopic study of hydrothermal synthetic KTP].

    PubMed

    Xie, Hao; Pei, Jing-Cheng; Qi, Li-Jian; Zhong, Zeng-Qiu

    2010-05-01

    In the present paper, different-generation hydrothermally grown KTP crystals were tested by the Nicolet 550 type FIR spectrometer with the reflective technique. They were studied on different crystal faces. Since the hydrothermally grown KTP crystal usually grows (100), (011) and (201) crystal faces, these faces were tested in different-generation products, and they were tested by two spectral wave bands, 2 000-4 000 and 400-2 000 cm(-1). The figures were compared with the flux-melt grown KTP crystal. In addition, making reference to the method of calculation about the consistence of OH- in quartz, the consistence of OH- in different -generation hydrothermally grown KTP crystals was estimated. In the hydrothermal grown KTP crystals, the stretching vibration of OH- shows distinct directivity characteristic. The absorption at [100] direction is obvious and the frequency is about 30 cm(-1) higher than the flux-melt grown KTP. Each new generation weakened the consistency of OH-, which restrained the growth of the KTP crystal. Accordingly, increasing the purity of rough materials plays a very important role in improving the quality of the crystals.

  17. Micro-Raman spectroscopic study of thyroid tissues.

    PubMed

    Medeiros Neto, Lázaro Pinto; das Chagas E Silva de Carvalho, Luis Felipe; Santos, Laurita Dos; Tellez Soto, Cláudio Alberto; de Azevedo Canevari, Renata; de Oliveira Santos, André Bandiera; Mello, Evandro Sobroza; Pereira, Marina Aparecida; Cernea, Cláudio Roberto; Brandão, Lenine Garcia; Martin, Aírton Abrahão

    2017-03-01

    Thyroid carcinomas are the most common endocrine malignancy. Inconclusive results for the analysis of malignancies are an issue in the diagnosis of thyroid carcinomas; 20% of thyroid cancer diagnoses are indeterminate or suspicious, resulting in a surgical procedure without immediate need. The use of Raman spectroscopy may help improve the diagnosis of thyroid carcinoma. In this study, 30 thyroid samples, including normal thyroid, goiter and thyroid cancer, were analyzed by confocal Raman spectroscopy. Principal component analysis (PCA), linear discriminant analysis (LDA) with cross validation and binary logistic regression (BLR) analysis were applied to discriminate among tissues. Significant discrimination was observed, with a consistent rate of concordant pairs of 89.2% for normal thyroid versus cancer, 85.7% for goiter versus cancer and 80.6% for normal thyroid versus goiter using just the amide III region. Raman spectroscopy was thus proven to be an important and fast tool for the diagnosis of thyroid tissues. The spectral region of 1200-1400cm(-1) discriminated normal versus goiter tissues despite the great similarity of these tissues.

  18. 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.

  19. Borax methylene blue: a spectroscopic and staining study.

    PubMed

    Donaldson, P T; Russo, A; Reynolds, C; Lillie, R D

    1978-07-01

    Borax methylene blue is quite stable at room temperatures of 22-25 C. At 30 C polychroming is slow; during 50 days in a water bath at this temperature the absorption peak moves from 665 to 656 nm. At 35 C, the absorption peak reaches 660 nm in 7 days, 654 nm in 14. At 60 C polychroming is rapid, the absorption peak reaching 640-620 nm in 3 days. When the pH of the borax methylene blue solutions, normally about 9.0, is adjusted to pH 6.5, the absorption peak remains at 665 nm even when incubated at 60 C for extended periods. When used as a blood stain 0.4 ml borax methylene blue (1% methylene blue in 1% borax), 4 ml acetone, 2 ml borax-acid phosphate buffer to bring the solution to pH 6.5, and distilled water to make 40 ml, with 0.2 ml 1% eosin added just before using, an excellent Nocht-Giemsa type stain is achieved after 30 minutes staining. The material plasmodia P. falciparum, P. vivax, and P. berghei stain moderate blue with dark red chromatin and green to black pigment granules. The study confirms Malachowski's 1891 results and explains Gautier's 1896-98 failure to duplicate it.

  20. A Spectroscopic Study of the Blue Component of Albireo

    NASA Astrophysics Data System (ADS)

    Whight, Kenneth R.

    2013-05-01

    This paper describes an investigation into what can be learned about the physical properties of the blue component of the Albireo double star system from both low (150 lines/mm) and high (2400 lines/mm) resolution spectra, based on the simple model that the star is a rotating uniformly emitting oblate spheroid with a photosphere that is a single layer in thermal equilibrium. The blue component of Albireo is an interesting target in that it exhibits emission at both Halpha and Hbeta wavelengths; this emission is believed to originate from an equatorial decretion disk spun off from the star. The aim of this work was to split the observed high resolution spectra into an absorption component, from the star, and an emission component, from the disk. To achieve this aim the continuum spectrum was modeled as a "black body" to obtain an effective temperature and the Hgamma absorption line was studied to obtain values for the star's model parameters. These results were then used to predict the expected absorption at Halpha and Hbeta wavelengths. Measured Halpha and Hbeta lines were then divided by their expected absorption lines to reveal the pure disk emission for further analysis.

  1. A spectroscopic study of laser ablation plasma from Mo target

    NASA Astrophysics Data System (ADS)

    Jakubowska, Katarzyna; Kubkowska, Monika; Blagoev, Alexander; Rosiński, Marcin; Parys, Piotr; Gąsior, Paweł

    2014-05-01

    The goal of this contribution is to present time-resolved optical spectroscopy studies of laser ablation of the Mo target with ˜ 3.5 ns, 0.4 J pulses delivered by the Nd-YAG laser system at 1.06 μm. The sample was placed in a vacuum chamber under 5 × 10-5 mbar pressure and irradiated, with power densities varied up to 22.7 GW cm-2. The ion emission from the plasma plume was measured using an electrostatic ion energy analyzer (IEA) and ion collector, which allowed us to estimate the ion kinetic energy and charge independent of the applied power densities. The signal collected by the IEA indicated the presence of molybdenum ions up to eight-ion charge. Simultaneously after the ion emission, the optical spectra acquired within 2 μs of exposure time were observed in the wavelength range from 200 to 1000 nm with a Mechelle 5000 spectrometer equipped with an iCCD (iStar) detector. The plasma electron temperature was estimated from a Boltzmann plot based on the registered spectra as well as from the ion measurements.

  2. 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.

  3. High resolution spectroscopic study of BeΛ10

    DOE PAGES

    Gogami, T.; Chen, C.; Kawama, D.; ...

    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

  4. Raman spectroscopic studies of gas/aerosol chemical reactions

    SciTech Connect

    Aardahl, C.L.; Davis, E.J.

    1995-12-31

    Reactions between sorbent particles and SO{sub 2} can be used to reduce atmospheric pollution either by {open_quotes}dry scrubbing{close_quotes} or {open_quotes}wet scrubbing{close_quotes} processes. This paper reports Raman spectroscopy results for single electrodynamically levitated droplets of NaOH reacting with SO{sub 2} and studies of the dehydration reactions of some hygroscopic salt species. The NaOH/SO{sub 2} reaction products and the liquid or solid state of the products are shown to depend on the gas phase SO{sub 2} concentration. Deliquesced particles of NaOH exhibit enhanced light scattering intensities associated with morphological resonances of the incident laser light, but crystalline materials show no such resonances. Raman-active hygroscopic salts exhibit bond frequencies characteristic of the stretching vibrations of the anionic group, but these frequencies are different in the presence of water because hydrogen bonding changes the bond force. This allows efficient tracking of the dehydration reactions in hygroscopic aerosols by Raman spectroscopy as the intensities of the two different modes are related to the degree of dehydration in the particle.

  5. 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.

  6. 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.

  7. 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.

  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. Influence of environment on piroxicam polymorphism: vibrational spectroscopic study.

    PubMed

    Taddei, P; Torreggiani, A; Simoni, R

    2001-01-01

    FTIR and FT-Raman spectroscopies were used to evaluate the mechanism of transformation of piroxicam into its different forms (alpha, beta, and monohydrate), depending on the environment. These vibrational techniques allowed us to identify the forms of piroxicam that crystallize from different solvents at different cooling rates and the conformation of the drug in some of its derivatives: piroxicam hydrochloride, piroxicam thallium and sodium salt hemihydrates, and piroxicam sodium salt. The usefulness of Raman spectroscopy in characterizing piroxicam:beta-cyclodextrin (PbetaCD) inclusion compounds was described. The Raman spectrum of 1:2 PbetaCD was discussed in comparison with that of the corresponding piroxicam sodium salt containing inclusion compound (1:2 PNabetaCD) in order to study the influence of the piroxicam derivative used on the structure of the inclusion compound. The Raman results showed that in both of the inclusion compounds the piroxicam mainly assumes the zwitterionic structure typical of a monohydrate; therefore, the kind of derivative used does not affect the conformation of the drug in its inclusion compound. The effect of the method of synthesis utilized (freeze-drying or freeze-thaw cycling) to obtain 1:2.5 PbetaCD was investigated. The inclusion compound obtained by freeze-thaw cycling proved to be more crystalline and to contain a higher amount of the beta form than the freeze-dried inclusion compound. Raman spectroscopy proved to be a useful technique for evaluating the effectiveness of the manufacturing process in relation to the pharmaceutical properties of the drug and to the nondestructive and noninvasive on-line quality control of the industrial products.

  10. Reaction and spectroscopic study of supported metal oxide catalysts

    NASA Astrophysics Data System (ADS)

    Ramani, Narayanan C.

    The role of surface structure, cation reducibility, surface acidity and the effect of the support was examined in the reaction of 1-butene over well characterized, supported metal oxide catalysts. Cr, Mo and W oxides supported on SiOsb2 were used to study the effect of structure, surface acidity and cation reducibility in the isomerization and selective oxidation of 1-butene. Supported oxides of Mo on TiOsb2,\\ Alsb2Osb3 and SiOsb2 were used to understand the role of the support in the selective oxidation of 1-butene. The surface acidity of SiOsb2 supported Cr, Mo, W and V oxide catalysts was examined by pyridine adsorption. Existing theoretical models of acidity were compared against experimental data. Over Mo(VI)/SiOsb2 and W(VI)/SiOsb2, isomerization through both a Bronsted catalyzed pathway and an allylic pathway were observed, while only the allylic pathway was observed over Cr(VI)/SiOsb2. The greater reducibility of the Cr cation compared to Mo and W cations was identified as the reason for the allylic pathway being dominant over Cr(VI)/SiOsb2. Cation reducibility was again seen to play an important role in the selective oxidation of 1-butene over SiOsb2 supported metal oxides. The turn over frequencies for 1,3-butadiene formation followed the trend in red-ox ability, with Cr > Mo > W. The activity to 1,3-butadiene formation did not change with increasing weight loading of Mo over TiOsb2 and Alsb2Osb3 supports. An analysis of the turn over frequencies of the supports and the supported cations revealed that a support effect, through the bridging oxygen ligand, dominated the intrinsic cation reducibility of Mo for these catalysts. The existence of Bronsted acidity over SiOsb2 supported Cr, Mo and V oxides was shown by an analysis of the OH region of the infrared spectrum, and by the adsorption of 1-butene and pyridine. Existing theoretical models for Bronsted acidity over supported metal oxides were shown to be inadequate to describe the observed results over

  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. 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.

  15. Use of neural networks for prediction of lateral reservoir porosity from seismic acoustic impedance: A case study from Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Alamoudi, Waleed Ahmad

    Reservoir porosity controls the strategies for reservoir management. Porosity is the primary key to a reliable reservoir model. The most economic method of evaluating reservoir porosity on a foot-by-foot basis is from core and well log data analysis. Lateral reservoir porosity is estimated using geostatistical method from well log data or from the integration of well log data and seismic data. However, the petroleum industry needs more accurate, reliable methods to estimate porosity from seismic data. Neural network analysis is one of the latest technologies available to the petroleum industry. In this study, I report results of an investigation of the use of neural network to predict lateral reservoir porosity. The approach is based on using average seismic acoustic impedances extracted from a 3D seismic volume to predict lateral average porosity for 13 reservoir geological layers. A neural network was trained using different subsets of well log data from 9 hydrocarbon wells and validated using the reminder of the wells. Data from the Unayzah reservoir in CNR field located in central basin of Saudi Arabia was used in this study. Model-based post-stack seismic inversion was used to produce a seismic acoustic impedance volume. Average impedance maps were then created for 13 layers from the Unayzah reservoir interval in the CNR field. Back-propagation neural network technique successfully estimated lateral reservoir porosity from seismic acoustic impedance and density attributes. The neural network performance using data from 6 wells (C, D, F, G, I, J), more or less distributed along the field axis, provided a better correlation and less scatter than other well training geometries in the testing phase. The A, B, and H wells were used for validation. Goodness of fit was 0.9985. The good neural network prediction in the testing phase reflects the neural network capability to estimate average reservoir porosities. Predicted lateral porosity maps incorporate

  16. Characterization of porcine skin as a model for human skin studies using infrared spectroscopic imaging.

    PubMed

    Kong, Rong; Bhargava, Rohit

    2011-06-07

    Porcine skin is often considered a substitute for human skin based on morphological and functional data, for example, for transdermal drug diffusion studies. A chemical, structural and temporal characterization of porcine skin in comparison to human skin is not available but will likely improve our understanding of this porcine skin model. Here, we employ Fourier transform infrared (FT-IR) spectroscopic imaging to holistically measure chemical species as well as spatial structure as a function of time to characterize porcine skin as a model for human skin. Porcine skin was found to resemble human skin spectroscopically and differences are elucidated. Cryo-prepared fresh porcine skin samples for spectroscopic imaging were found to be stable over time and small variations are observed. Hence, we extended characterization to the use of this model for dynamic processes. In particular, the capacity and stability of this model in transdermal diffusion is examined. The results indicate that porcine skin is likely to be an attractive tool for studying diffusion dynamics of materials in human skin.

  17. Comparative electrochemical and impedance studies of self-assembled rigid-rod molecular wires and alkanethiols on gold substrates.

    PubMed

    Aguiar, Francisco A; Campos, Rui; Wang, Changsheng; Jitchati, Rukkiat; Batsanov, Andrei S; Bryce, Martin R; Kataky, Ritu

    2010-11-28

    A study of the charge transfer and self-assembly characteristics of two new rigid-rod molecular wires 1 and 2 assembled on polycrystalline gold electrodes was carried out using electrochemical impedance spectroscopy and cyclic voltammetry. This class of wires have precisely controlled (ca. 1.5-2.5 nm) lengths of π-conjugation, with extended HOMO and LUMO wavefunctions. While rotations can occur around the C-C single bonds, the molecules cannot isomerise or fold due to their rigid backbone structures. The behaviour of these wires was compared with SAMs of heptanethiol (HPT) and dodecanethiol (DDT). It was found that SAMs of 1, which bears flexible hexyloxy sidechains, had randomly distributed pinholes which show microelectrode behaviour even when diluted with DDT. SAMs of 2, which do not have any sidechains, were well-organised at open-circuit potentials enabling evaluation of electron transfer kinetics assuming an average film thickness. However, impedance studies show that deviations from open circuit potentials resulted in an exponential decrease in charge transfer resistance, whereas capacitance remained constant, possibly attributable to conformational changes of the SAM. The syntheses and characterisation of the molecules is described.

  18. Impedance spectroscopy study of a catechol-modified activated carbon electrode as active material in electrochemical capacitor

    NASA Astrophysics Data System (ADS)

    Cougnon, C.; Lebègue, E.; Pognon, G.

    2015-01-01

    Modified activated carbon (Norit S-50) electrodes with electrochemical double layer (EDL) capacitance and redox capacitance contributions to the electric charge storage were tested in 1 M H2SO4 to quantify the benefit and the limitation of the surface redox reactions on the electrochemical performances of the resulting pseudo-capacitive materials. The electrochemical performances of an electrochemically anodized carbon electrode and a catechol-modified carbon electrode, which make use both EDL capacitance of the porous structure of the carbon and redox capacitance, were compared to the performances obtained for the pristine carbon. Nitrogen gas adsorption measurements have been used for studying the impact of the grafting on the BET surface area, pore size distribution, pore volume and average pore diameter. The electrochemical behavior of carbon materials was studied by cyclic voltammetry and electrochemical impedance spectroscopy (EIS). The EIS data were discussed by using a complex capacitance model that allows defining the characteristic time constant, the global capacitance and the frequency at which the maximum charge stored is reached. The EIS measurements were achieved at different dc potential values where a redox activity occurs and the evolution of the capacitance and the capacitive relaxation time with the electrode potential are presented. Realistic galvanostatic charge/discharge measurements performed at different current rates corroborate the results obtained by impedance.

  19. Computational studies of the electronic, conductivities, and spectroscopic properties of hydrolysed Ru(II) anticancer complexes.

    PubMed

    Adeniyi, Adebayo A; Ajibade, Peter A

    2013-11-01

    The mechanism of activation of metal-based anticancer agents was reported to be through hydrolysis. In this study, computational method was used to gain insight to the correlation between the chemistry of the hydrolysis and the anticancer activities of selected Ru(II)-based complexes. Interestingly, we observed that the mechanism of activation by hydrolysis and their consequential anticancer activities is associated with favourable thermodynamic changes, higher hyperpolarizability (β), lower band-gap and higher first-order net current. The Fermi contact (FC) and spin dipole (SD) are found to be the two most significant Ramsey terms that determine the spin-spin couplings (J(HZ)) of most of the existing bonds in the complexes. Many of the computed properties give insights into the change in the chemistry of the complexes due to hydrolysis. Besides strong correlations of the computed properties to the anticancer activities of the complexes, using the quantum theory of atoms in a molecule (QTAIM) to analyse the spectroscopic properties shows a stronger correlation between the spectroscopic properties of Ru atom to the reported anticancer activities than the sum over of the spectroscopic properties of all atoms in the complexes.

  20. Computational studies of the electronic, conductivities, and spectroscopic properties of hydrolysed Ru(II) anticancer complexes

    NASA Astrophysics Data System (ADS)

    Adeniyi, Adebayo A.; Ajibade, Peter A.

    2013-11-01

    The mechanism of activation of metal-based anticancer agents was reported to be through hydrolysis. In this study, computational method was used to gain insight to the correlation between the chemistry of the hydrolysis and the anticancer activities of selected Ru(II)-based complexes. Interestingly, we observed that the mechanism of activation by hydrolysis and their consequential anticancer activities is associated with favourable thermodynamic changes, higher hyperpolarizability (β), lower band-gap and higher first-order net current. The Fermi contact (FC) and spin dipole (SD) are found to be the two most significant Ramsey terms that determine the spin-spin couplings (J(HZ)) of most of the existing bonds in the complexes. Many of the computed properties give insights into the change in the chemistry of the complexes due to hydrolysis. Besides strong correlations of the computed properties to the anticancer activities of the complexes, using the quantum theory of atoms in a molecule (QTAIM) to analyse the spectroscopic properties shows a stronger correlation between the spectroscopic properties of Ru atom to the reported anticancer activities than the sum over of the spectroscopic properties of all atoms in the complexes.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Electrochemical Impedance Studies on Tribocorrosion Behavior of Plasma-Sprayed Al2O3 Coatings

    NASA Astrophysics Data System (ADS)

    Liu, Zhe; Chu, Zhenhua; Chen, Xueguang; Dong, Yanchun; Yang, Yong; Li, Yingzhen; Yan, Dianran

    2015-06-01

    In this paper, the tribocorrosion of plasma-sprayed Al2O3 coatings in simulated seawater was investigated by electrochemical impedance spectroscopy (EIS) technique, complemented by scanning electron microscopy to observe the morphology of the tribocorrosion attack. Base on EIS of plasma-sprayed Al2O3 coatings undergoing long-time immersion in simulated seawater, the corrosion process of Al2O3 coatings can be divided into the earlier stage of immersion (up to 20 h) and the later stage (beyond 20 h). Then, the wear tests were carried out on the surface of Al2O3 coating undergoing different times of immersion to investigate the influence of wear on corrosion at different stages. The coexistence of wear and corrosion condition had been created by a boron nitride grinding head rotating on the surface of coatings corroded in simulated seawater. The measured EIS and the values of the fitting circuit elements showed that wear accelerated corrosion at the later stage, meanwhile, corrosion accelerated wear with the immersion time increasing.

  6. Phase, thermal and impedance studies of nanosize LiWO via mechanical milling and sintering

    NASA Astrophysics Data System (ADS)

    Han, Tan Kim; Ahmad, Roslina; Johan, Mohd Rafie

    2011-01-01

    Nanosize Li 2WO 4 is successfully synthesized using a mechanical milling method. The mean particle size of milled Li 2WO 4 is 37 nm and 31 nm as measured by Transmission Electron Microscopy (TEM) and X-ray diffraction (XRD) analysis, respectively. The calculated lattice parameter of as-received and milled powder are 0.8326 and 0.8321 nm, respectively. Both powders have been hydrated at room temperature and are highly crystalline with the presence of different types of phases at varying sintering temperatures. There is no Li 2W 2O 7 (JCPDS 28-0598) phase present in the milled powder during the whole sintering process. Meanwhile, the thermogravimetric analysis (TGA) of both powders is in accordance with their phase changes as presented in the XRD spectra. The impedance measurements show that the milled powder has a lower conductivity than that of the as-received powder in overall. The conductivity of the as-received powder increases with sintering temperature but this phenomenon is vice versa for the milled powder. All these trends can be correlated with the Field Emission Scanning Electron Microscopy (FE-SEM) micrographs on both powders.

  7. 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.

  8. Synthesis, structural and spectroscopic studies of two new benzimidazole derivatives: A comparative study

    NASA Astrophysics Data System (ADS)

    Saral, Hasan; Özdamar, Özgür; Uçar, İbrahim

    2017-02-01

    In the present work, structural and spectroscopic studies on 1-Methyl-2-(2‧-hydroxy-4‧-chlorophenyl)benzimidazole (1) and 1-Methyl-2-(2‧-hydroxy-4‧-methoxyphenyl)benzimidazole (2), have been carried out extensively by X-ray diffraction, HRMS, UV-Vis, FT-IR and 1H and 13C NMR spectroscopy. The crystal structure of both compounds is stabilized by Osbnd H⋯N hydrogen bond and π-π interactions. Contrary to compound 1, the skeleton of compound 2 is considerably deviated from the planarity probably caused by intermolecular hydrogen bonding. The experimental results were compared to the theoretical ones, obtained at DFT level. Ground state geometry, electronic structure, vibrational and NMR spectra have been performed using the B3LYP functional with the 6-31 G(d,p) basis set. It was observed that the bond distances and angles in the both compounds were in good with those of the experiment. The energetic behaviors of the both compounds in methanol solvent were examined using by time-dependent DFT (TD-DFT) method by applying the polarizable continuum model (PCM). Isotropic chemical shifts (13C and 1H NMR) were calculated using the gauge-invariant atomic orbital (GIAO) method. The HOMO and LUMO analyses were used to elucidate information regarding charge transfer within the molecule.

  9. Fourier transform Raman spectroscopic studies of a novel wood pulp bleaching system

    NASA Astrophysics Data System (ADS)

    Weinstock, Ira A.; Atalla, Rajai H.; Agarwal, Umesh P.; Minor, James L.; Petty, Chris

    1993-06-01

    The use of near-infrared (NIR) Fourier transform (FT) Raman spectroscopy for the study of lignocellulosic materials is discussed. An application utilizing NIR FT-Raman spectroscopy to study a novel chlorine-free process for the bleaching of wood pulps is presented in detail. The new process, still under development, entails the oxidation of residual lignin in wood pulps by vanadium-substituted polyoxometalates, and reoxidation of the reduced polyoxometalates by chlorine-free oxidants such as air, dioxygen, peroxides or ozone. Results from FT-Raman measurements of polyoxometalate-treated pulps are compared with those from chemical, spectroscopic and optical techniques commonly used in the pulp and paper industry.

  10. 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.

  11. Study of spectroscopic and thermal characteristics of nonlinear optical molecular crystals based on 4-nitrophenol

    NASA Astrophysics Data System (ADS)

    Pavlovetc, I. M.; Fokina, M. I.

    2016-08-01

    The paper presents the results of study of spectroscopic and thermal characteristics of molecular co-crystals: 2-aminopyridine-4-nitrophenol-4-mtrophenolate (2AP4N) and 2,6- diaminopyridine-4-nitrophenol-4nitrophenolate (26DAP4N). Crystals were successfully grown by slow evaporation technique. Optical transparency in the region of 190-1100 was found to be suitable for applications with cut off wavelengths 420 and 430 nm respectively. Thermogravimetric and differential thermal analysis show good quality and thermal stability for studied crystals. Kurtz and Perry powder technique proves that the crystals are acentric and have significant nonlinear optical response.

  12. High-Resolution Photoionization, Photoelectron and Photodissociation Studies. Determination of Accurate Energetic and Spectroscopic Database for Combustion Radicals and Molecules

    SciTech Connect

    Ng, Cheuk-Yiu

    2016-04-25

    The main goal of this research program was to obtain accurate thermochemical and spectroscopic data, such as ionization energies (IEs), 0 K bond dissociation energies, 0 K heats of formation, and spectroscopic constants for radicals and molecules and their ions of relevance to combustion chemistry. Two unique, generally applicable vacuum ultraviolet (VUV) laser photoion-photoelectron apparatuses have been developed in our group, which have used for high-resolution photoionization, photoelectron, and photodissociation studies for many small molecules of combustion relevance.

  13. Quantitative non-linear ultrasonic imaging of targets with significant acoustic impedance contrast--an experimental study.

    PubMed

    Guillermin, Régine; Lasaygues, Philippe; Rabau, Guy; Lefebvre, Jean-Pierre

    2013-08-01

    This study deals with the reconstruction, from ultrasonic measured data, of the sound speed profile of a penetrable two-dimensional target of arbitrary cross-section embedded in an infinite medium. Green's theorem is used to obtain a domain integral representation of the acoustical scattered field, and a discrete formulation of the inverse problem is obtained using a moment method. An iterative non-linear algorithm minimizing the discrepancy between the measured and computed scattered fields is used to reconstruct the sound speed profile in the region of interest. The minimization process is performed using a conjugated-gradient method. An experimental study with significant acoustical impedance contrast targets immersed in water was performed. Images of the sound speed profile obtained by inversion of experimental data are presented.

  14. Experimental Study on Damage Detection in Timber Specimens Based on an Electromechanical Impedance Technique and RMSD-Based Mahalanobis Distance.

    PubMed

    Wang, Dansheng; Wang, Qinghua; Wang, Hao; Zhu, Hongping

    2016-10-22

    In the electromechanical impedance (EMI) method, the PZT patch performs the functions of both sensor and exciter. Due to the high frequency actuation and non-model based characteristics, the EMI method can be utilized to detect incipient structural damage. In recent years EMI techniques have been widely applied to monitor the health status of concrete and steel materials, however, studies on application to timber are limited. This paper will explore the feasibility of using the EMI technique for damage detection in timber specimens. In addition, the conventional damage index, namely root mean square deviation (RMSD) is employed to evaluate the level of damage. On that basis, a new damage index, Mahalanobis distance based on RMSD, is proposed to evaluate the damage severity of timber specimens. Experimental studies are implemented to detect notch and hole damage in the timber specimens. Experimental results verify the availability and robustness of the proposed damage index and its superiority over the RMSD indexes.

  15. Experimental Study on Damage Detection in Timber Specimens Based on an Electromechanical Impedance Technique and RMSD-Based Mahalanobis Distance

    PubMed Central

    Wang, Dansheng; Wang, Qinghua; Wang, Hao; Zhu, Hongping

    2016-01-01

    In the electromechanical impedance (EMI) method, the PZT patch performs the functions of both sensor and exciter. Due to the high frequency actuation and non-model based characteristics, the EMI method can be utilized to detect incipient structural damage. In recent years EMI techniques have been widely applied to monitor the health status of concrete and steel materials, however, studies on application to timber are limited. This paper will explore the feasibility of using the EMI technique for damage detection in timber specimens. In addition, the conventional damage index, namely root mean square deviation (RMSD) is employed to evaluate the level of damage. On that basis, a new damage index, Mahalanobis distance based on RMSD, is proposed to evaluate the damage severity of timber specimens. Experimental studies are implemented to detect notch and hole damage in the timber specimens. Experimental results verify the availability and robustness of the proposed damage index and its superiority over the RMSD indexes. PMID:27782088

  16. A preliminary study of reliability of impedance measurement to detect iatrogenic initial pedicle perforation (in the porcine model).

    PubMed

    Bolger, Ciaran; Carozzo, C; Roger, T; McEvoy, Linda; Nagaria, Jabir; Vanacker, Gerard; Bourlion, Maurice

    2006-03-01

    Accidental perforation of the vertebral pedicle wall is a well-known complication associated with standard approach of pedicle screw insertion. Depending on detection criteria, more than 20% of screws are reported misplaced. Serious clinical consequences, from dysesthesia to paraplegia, although not common, may result from these misplaced screws. Many techniques have been described to address this issue such as somatosensory evoked potentials, electromyography, surgical navigation, etc. Each of these techniques presents advantages and drawbacks, none is simple and ergonomic. A new drilling tool was evaluated which allows for instant detection of pedicle perforation by emission of variable beeps. This new device is based on two original principles: the device is integrated in the drilling or screwing tool, the technology allows real-time detection of perforation through two independent parameters, impedance variation and evoked muscular contractions. A preliminary animal study was conducted to assess the safety and efficacy of this system based upon electrical conductivity. A total of 168 manual pedicle drillings followed by insertion of implants were performed in 11 young porcine lumbar and thoracic spines. The presence or absence of perforation detection, which defines the reliability of the device, was correlated with necropsic examination of the spines. Using this protocol the device demonstrated 100% positive predictive value, 96% negative predictive value, 100% specificity, and 97% sensitivity. Of 168 drillings there were three (1.79%) false-negatives, leading to a minor effraction, cranially in the intervertebral disks, nine (5.36%) screw threads breaching the vertebral cortex when inserting screws, although preparation of the holes did not indicate any perforation, 34 (36%) breaches detected by the instrument and not detected by the surgeon. These results confirm that the impedance variation detection capability of this device offers a simple and effective

  17. 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.

  18. A spectroscopic study of the radial velocity variations and accretion disks found in four dwarf novae

    NASA Astrophysics Data System (ADS)

    Stover, R. J.

    Time resolved spectroscopic observations of the four dwarf novae SS Cyg, EM Cyg, U Gem, and RU Peg are presented. Although these systems were studied previously, all of the spectroscopic studies were done photographically. A linear response, digital detector is employed. Analytic techniques to the study of the radial velocity variations and emission line profiles found in dwarf novae are applied. In the study of SS Cyg cross-correlation techniques were used for the first time to measure the radial velocity variations of the secondary star absorption lines. In the study of U Gem, analysis of the accretion disk emission lines showed that the motion of the material in the disk cannot be described accurately by orbits defined within the three-body approximation. The observations of EM Cyg reveal an unstable accretion disk, with emission lines that vary erratically on timescales of minutes to days. New measurements of the radial velocity variations of the emission and absorption lines found in the spectrum of RU Peg agree with previous measurements but have a higher accuracy.

  19. 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.

  20. On-line separator for {gamma}-spectroscopic studies at FLNR JINR

    SciTech Connect

    Popeko, A. G.; Belozerov, A. V.; Chepigin, V. I.; Kabachenko, A. P.; Malyshev, O. N.; Shutov, A. V.; Svirikhin, A. I.; Yeremin, A. V.; Dorvaux, O.; Hauschild, K.; Korichi, A.; Lopez-Martens, A.

    2007-05-22

    A JINR - IN2P3 collaboration project named 'GABRIELA' aimed at the nuclear spectroscopy of transfermium elements using the recoil separator VASSILISSA was launched in 2004 at JINR in Dubna. In the close future the FLNR cyclotron U400M will go through a major upgrade with the goal to deliver heavy ion beams at the energy close to the Coulomb barrier in a new experimental area. Here we report about R and D of the new separator for spectroscopic studies which we plan to install at the beam of the modernized accelerator and which will allow to realize new possibilities of the GABRIELA project.

  1. On-line separator for γ-spectroscopic studies at FLNR JINR

    NASA Astrophysics Data System (ADS)

    Popeko, A. G.; Belozerov, A. V.; Chepigin, V. I.; Dorvaux, O.; Hauschild, K.; Kabachenko, A. P.; Korichi, A.; Lopez-Martens, A.; Malyshev, O. N.; Shutov, A. V.; Svirikhin, A. I.; Yeremin, A. V.

    2007-05-01

    A JINR — IN2P3 collaboration project named "GABRIELA" aimed at the nuclear spectroscopy of transfermium elements using the recoil separator VASSILISSA was launched in 2004 at JINR in Dubna. In the close future the FLNR cyclotron U400M will go through a major upgrade with the goal to deliver heavy ion beams at the energy close to the Coulomb barrier in a new experimental area. Here we report about R&D of the new separator for spectroscopic studies which we plan to install at the beam of the modernized accelerator and which will allow to realize new possibilities of the GABRIELA project.

  2. HeI photoelectron spectroscopic studies on the electronic structure of alkyl nitrosamines

    NASA Astrophysics Data System (ADS)

    Jiang, Peng; Qian, Ximei; Li, Chunhui; Qiao, Chunhua; Wang, Dianxun

    1997-10-01

    HeI photoelectron spectroscopic (PES) studies on the electronic structure of alkyl nitrosamines R 2N 2O (R = CH 3-, CH 3CH 2-, and CH 3CH 2CH 2-) are reported. The assignment of the PES bands for this series of compounds has been made with the aid of the band shapes, the band intensity and ab initio SCF MO calculations based on the 631 ∗ G basis sets. Both PES experiment and the ab initio SCF MO calculations show that the detoxification ability of nitrosamine with longer alkyl chain is stronger.

  3. Dielectric properties of WS2-coated multiwalled carbon nanotubes studied by energy-loss spectroscopic profiling

    NASA Astrophysics Data System (ADS)

    Stolojan, Vlad; Silva, S. R. P.; Goringe, Michael J.; Whitby, R. L. D.; Hsu, Wang K.; Walton, D. R. M.; Kroto, Harold W.

    2005-02-01

    We investigate experimentally the electronic properties of the coating for multiwalled carbon nanotubes covered in tungsten disulfide (WS2) of various thicknesses. Coatings of thicknesses between 2 and 8 monolayers (ML) are analyzed using energy-loss spectroscopic profiling (ELSP), by studying the variations in the plasmon excitations across the coated nanotube, as a function of the coating thickness. We find a change in the ELSP for coatings above 5 ML thickness, which we interpret in terms of a change in its dielectric properties.

  4. Iranian staff nurses' views of their productivity and management factors improving and impeding it: a qualitative study.

    PubMed

    Dehghan Nayeri, Nahid; Nazari, Ali Akbar; Salsali, Mahvash; Ahmadi, Fazlollah; Adib Hajbaghery, Mohsen

    2006-03-01

    As the biggest proportion of hospital personnel, Iranian nurses have a major role in providing quality care to patients. Nursing managers and nurses no longer feel that nurses' work is valued and they are concerned about their productivity. Nurses' views about productivity and management factors affecting it have been identified as the most important aspects affecting productivity. Thus, this study assesses productivity from the nurse's view. A grounded theory approach was used for this research. Purposive sampling and semistructured interviews were used. The data were analyzed using constant comparative analysis. Most participants felt that the qualitative nature (effectiveness) of productivity is very important. Also, participants indicated that management is the most important factor that can promote or impede their productivity. They suggested that managers' performance and their skill level are the factors influencing productivity. Effective management can improve nurses' productivity and the quality of care that nurses provide.

  5. Electrochemistry of conductive polymers 40. Earlier phases of aniline polymerization studied by Fourier transform electrochemical impedance spectroscopy.

    PubMed

    Hong, Sung-Young; Park, Su-Moon

    2007-08-23

    Earlier stages of aniline polymerization have been studied by Fourier transform electrochemical impedance spectroscopy (FTEIS) experiments. Initial oxidation of aniline leads to the formation of a thin layer passivating the electrode surface, which is depassivated upon a further increase in potential and mediates a further electron transfer from aniline to the electrode. The charge-transfer resistance was first shown to decrease upon increasing the potential, which leads to the inductive behavior upon further increase in the overpotential. The oligomer-polymer film thus formed was shown to undergo a transition from its passive state to neutral oligomer-polymer molecules via a conducting state; its oxidation was then observed during the anodic scan. It is this transition to the conductive states that leads to the propagation of the conductive zone throughout the nonconductive film, leading to further growth of polyaniline, as was clearly shown by the FTEIS measurements.

  6. AC impedance spectroscopy studies on solid-state sintered zinc aluminum oxide (ZnAl2O4) ceramics

    NASA Astrophysics Data System (ADS)

    Kumar, B. Rajesh; Rao, T. Subba

    2012-07-01

    In the present investigation Zinc Aluminum Oxide (ZnAl2O4) is prepared by solid-state reaction technique. Dielectric constant (ɛ'), dielectric loss(tan δ), ac conductivity (σac) as a function of temperature are studied by varying frequencies from 100 Hz to 1MHz using an impedance analyzer. The dielectric constant and dielectric loss increases gradually with an increase of temperature, but it decreases with increase of frequency. The ac conductivity (σac) also increases with increases of frequency. The transition peaks for ZnAl2O4 are observed at 490°C, 510°C, 520°C for the frequencies 1 KHz, 10 KHz and 100 KHz. No transition peaks are found for the frequency 100 Hz and 1 MHz because of high conductive loss.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Majorana Neutrino Masses by Spectroscopic Studies of Double Beta Decays and Moon

    NASA Astrophysics Data System (ADS)

    Ejiri, Hiroyasu

    This is a brief review of spectroscopic studies of neutrino-less double beta decays (0νββ) and the MOON (Mo Observatory Of Neutrinos) project. It aims at studying the Majorana nature of neutrinos and the mass spectrum by spectroscopic studies of 0νββ with ν-mass sensitivity of ≈ 30 meV. The solid scintillator option of the MOON detector is a super ensemble of multi-layer modules, each being composed by a scintillator plate and two tracking detector planes. Thin ββ source films are interleaved between the detector planes. High localization of the two β tracks enables one to select true signals and reject BG ones by spatial and time correlation analyses. MOON with detector ≠ ββ source is used for studying 0νββ decays from 100Mo, 82Se and other ββ isotopes with large nuclear sensitivity (large Qββ). Real-time exclusive measurements of low energy solar neutrinos can also be made by observing inverse β rays from solar-ν captures of 100Mo in delayed coincidence with the subsequent β decay of 100Tc.

  12. The Distance to the Massive Galactic Cluster Westerlund 2 from a Spectroscopic and HST Photometric Study

    NASA Astrophysics Data System (ADS)

    Vargas Álvarez, Carlos A.; Kobulnicky, Henry A.; Bradley, David R.; Kannappan, Sheila J.; Norris, Mark A.; Cool, Richard J.; Miller, Brendan P.

    2013-05-01

    We present a spectroscopic and photometric determination of the distance to the young Galactic open cluster Westerlund 2 using WFPC2 imaging from the Hubble Space Telescope (HST) and ground-based optical spectroscopy. HST imaging in the F336W, F439W, F555W, and F814W filters resolved many sources previously undetected in ground-based observations and yielded photometry for 1136 stars. We identified 15 new O-type stars, along with two probable binary systems, including MSP 188 (O3 + O5.5). We fit reddened spectral energy distributions based on the Padova isochrones to the photometric data to determine individual reddening parameters RV and AV for O-type stars in Wd2. We find average values langRV rang = 3.77 ± 0.09 and langAV rang = 6.51 ± 0.38 mag, which result in a smaller distance than most other spectroscopic and photometric studies. After a statistical distance correction accounting for close unresolved binaries (factor of 1.08), our spectroscopic and photometric data on 29 O-type stars yield that Westerlund 2 has a distance langdrang = 4.16 ± 0.07 (random) +0.26 (systematic) kpc. The cluster's age remains poorly constrained, with an upper limit of 3 Myr. Finally, we report evidence of a faint mid-IR polycyclic aromatic hydrocarbon ring surrounding the well-known binary candidate MSP 18, which appears to lie at the center of a secondary stellar grouping within Westerlund 2. Based on observations obtained at the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Ministério da Ciência, Tecnologia, e Inovação (MCTI) da República Federativa do Brasil, the U.S. National Optical Astronomy Observatory (NOAO), the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU).

  13. THE DISTANCE TO THE MASSIVE GALACTIC CLUSTER WESTERLUND 2 FROM A SPECTROSCOPIC AND HST PHOTOMETRIC STUDY

    SciTech Connect

    Vargas Alvarez, Carlos A.; Kobulnicky, Henry A.; Bradley, David R.; Kannappan, Sheila J.; Norris, Mark A.; Cool, Richard J.; Miller, Brendan P. E-mail: chipk@uwyo.edu E-mail: sheila@physics.unc.edu E-mail: rcool@obs.carnegiescience.edu

    2013-05-15

    We present a spectroscopic and photometric determination of the distance to the young Galactic open cluster Westerlund 2 using WFPC2 imaging from the Hubble Space Telescope (HST) and ground-based optical spectroscopy. HST imaging in the F336W, F439W, F555W, and F814W filters resolved many sources previously undetected in ground-based observations and yielded photometry for 1136 stars. We identified 15 new O-type stars, along with two probable binary systems, including MSP 188 (O3 + O5.5). We fit reddened spectral energy distributions based on the Padova isochrones to the photometric data to determine individual reddening parameters R{sub V} and A{sub V} for O-type stars in Wd2. We find average values (R{sub V} ) = 3.77 {+-} 0.09 and (A{sub V} ) = 6.51 {+-} 0.38 mag, which result in a smaller distance than most other spectroscopic and photometric studies. After a statistical distance correction accounting for close unresolved binaries (factor of 1.08), our spectroscopic and photometric data on 29 O-type stars yield that Westerlund 2 has a distance (d) = 4.16 {+-} 0.07 (random) +0.26 (systematic) kpc. The cluster's age remains poorly constrained, with an upper limit of 3 Myr. Finally, we report evidence of a faint mid-IR polycyclic aromatic hydrocarbon ring surrounding the well-known binary candidate MSP 18, which appears to lie at the center of a secondary stellar grouping within Westerlund 2.

  14. 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.

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

    PubMed

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

    2016-02-05

    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.

  16. A combined spectroscopic and TDDFT study of natural dyes extracted from fruit peels of Citrus reticulata and Musa acuminata for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Prima, Eka Cahya; Hidayat, Novianto Nur; Yuliarto, Brian; Suyatman; Dipojono, Hermawan Kresno

    2017-01-01

    This study reports the novel spectroscopic investigations and enhanced the electron transfers of Citrus reticulata and Musa acuminata fruit peels as the photosensitizers for the dye-sensitized solar cells. The calculated TD-DFT-UB3LYP/6-31 + G(d,p)-IEFPCM(UAKS), experiment spectra of ultra-violet-visible spectroscopy, and Fourier transform infrared spectroscopy studies indicate the main flavonoid (hesperidin and gallocatechin) structures of the dye extracts. The optimized flavonoid structures are calculated using Density functional theory (DFT) at 6-31 + G(d,p) level. The rutinosyl group of the hesperidin pigment (Citrus reticulata) will be further investigated compared to the gallocatechin (Musa acuminata) pigment. The acidity of the dye extract is treated by adding 2% acetic acid. The energy levels of the HOMO-LUMO dyes are measured by a combined Tauc plot and cyclic voltammetry contrasted with the DFT data. The electrochemical impedance spectroscopy will be performed to model the dye electron transfer. As for the rutinosyl group presence and the acidic treatment, the acidified Citrus reticulata cell under continuous light exposure of 100 mW·cm- 2 yields a short-circuit current density (Jsc) of 3.23 mA/cm2, a photovoltage (Voc) of 0.48 V, and a fill factor of 0.45 corresponding to an energy conversion efficiency (η) of 0.71% because the shifting down HOMO-LUMO edges and the broadening dye's absorbance evaluated by a combined spectroscopic and TD-DFT method. The result also leads to the longest diffusion length of 32.2 μm, the fastest electron transit of 0.22 ms, and the longest electron lifetime of 4.29 ms.

  17. 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.

  18. 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

  19. Vibrational spectroscopic study of newly developed self-forming lipids and nanovesicles.

    NASA Astrophysics Data System (ADS)

    Bista, Rajan; Bruch, Reinhard

    2009-03-01

    We present the first experimental study of self-forming synthetic nanovesicles, trademarked as QuSomes, using vibrational spectroscopic techniques namely near-infrared (NIR) and laser tweezers Raman spectroscopy. Raman spectra of these new artificial nanovesicles suspended in Phosphate Buffered Saline (PBS) have been obtained by using an inverted confocal laser-tweezers-Raman-microscopy system in the spectral range of 3100 to 500 cm-1. This spectrometer works with an 80 mW diode-pumped solid-state laser, operating at a wavelength of 785 nm in the TEM00 mode. The laser is used both for optical trapping and Raman excitation. Similarly, NIR absorption spectra of these novel nanovesicles have been recorded in the spectral range of 9000-4800 cm-1 by using a new miniaturized micro-mirror spectrometer based on micro-optical-electro-mechanical systems (MOEMS) technology. In this work, we have found that the most prominent bands in the studied spectral region of Raman spectra are dominated by vibrational modes arising from C-C and CH2 bonds. Similarly, NIR spectra are primarily assigned as first and second overtone of C-H stretching mode and second overtone of C=O stretching mode. These spectroscopic techniques have proven to be an excellent tool to establish the fingerprint region revealing the molecular structure and conformation of QuSomes nanoparticles.

  20. Spectroscopic Study on Ultrafast Carrier Dynamics and Terahertz Amplified Stimulated Emission in Optically Pumped Graphene

    NASA Astrophysics Data System (ADS)

    Otsuji, Taiichi; Boubanga-Tombet, Stephane; Satou, Akira; Suemitsu, Maki; Ryzhii, Victor

    2012-08-01

    This paper reviews recent advances in spectroscopic study on ultrafast carrier dynamics and terahertz (THz) stimulated emission in optically pumped graphene. The gapless and linear energy spectra of electrons and holes in graphene can lead to nontrivial features such as negative dynamic conductivity in the THz spectral range, which may lead to the development of new types of THz lasers. First, the non-equilibrium carrier relaxation/recombination dynamics is formulated to show how photoexcited carriers equilibrate their energy and temperature via carrier-carrier and carrier-phonon scatterings and in what photon energies and in what time duration the dynamic conductivity can take negative values as functions of temperature, pumping photon energy/intensity, and carrier relaxation rates. Second, we conduct time-domain spectroscopic studies using an optical pump and a terahertz probe with an optical probe technique at room temperature and show that graphene sheets amplify an incoming terahertz field. Two different types of samples are prepared for the measurement; one is an exfoliated monolayer graphene on SiO2/Si substrate and the other is a heteroepitaxially grown non-Bernal stacked multilayer graphene on a 3C-SiC/Si epi-wafer.

  1. Theoretical study of spectroscopic constants and anharmonic force field of SiF2.

    PubMed

    Li, Jing; Wang, Meishan; Yang, Chuanlu; Ma, Meizhong; Tong, Dianmin

    2015-05-01

    The equilibrium structure, spectroscopy constants, and anharmonic force field of SiF2 have been investigated at MP2, B3LYP, and B3PW91 levels of theory employing two basis sets cc-pVQZ and cc-pVTZ, respectively. The obtained equilibrium geometries, rotational constants, fundamental vibrational wave numbers, and centrifugal distortion constants are compared with the available experimental data or the previous theoretical values. The MP2/cc-pVQZ results of SiF2 are in excellent agreement with the available experimental data and afford a marked improvement over B3LYP/cc-pVQZ and B3PW91/cc-pVQZ in the calculation of spectroscopic constants and force constants of SiF2. The basis set enhancement beyond cc-pVQZ does not lead to a major improvement so that the cc-pVQZ basis set is sufficient for SiF2. The MP2/cc-pVQZ results may provide useful data for the spectroscopic experiment studies of SiF2. The used DFT method is also an advisable choice to study anharmonic force field of SiF2.

  2. 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.

  3. Electron spectroscopic study (ESI, EELS) of Nanoplast-embedded mammalian lung.

    PubMed

    Fehrenbach, H; Richter, J; Schnabel, P A

    1992-06-01

    The potential of Nanoplast melamine resin embedding for the study of mammalian lung parenchyma was examined by means of electron spectroscopic imaging (ESI) and electron energy-loss spectroscopy (EELS). Samples were either fixed with glutaraldehyde-paraformaldehyde or glutaraldehyde-tannic acid, or were directly transferred to the embedding medium without prior fixation. Organic dehydrants, as well as fixatives containing heavy metals and stains, were omitted. A very high level of ultrastructural detail of chromatin, ribosomes, mitochondria and plasma membranes was achieved by ESI from the Nanoplast-embedded samples. The most prominent gain in ultrastructural detail was achieved when moving from an energy loss just below the L2,3 edge of phosphorus at 132 eV to an energy loss just beyond this edge. This reflects the prominent P L2,3 edge observed by EELS of Nanoplast-embedded samples in comparison with conventionally processed samples. Thus, taking into account possible sectioning artefacts, excellent heterochromatin images which rely on the phosphorus distribution can be obtained from Nanoplast-embedded samples by computer-assisted analysis of electron spectroscopic images. In this respect glutaraldehyde-paraformaldehyde fixation is preferable to glutaraldehyde-tannic acid fixation because the presence of silicon, revealed by EELS, in tannic-acid-fixed samples may introduce artefacts in phosphorus distribution images obtained by the three-window method because of the close proximity of the L2,3 edges of silicon and phosphorus.

  4. Spectroscopic study of honey from Apis mellifera from different regions in Mexico.

    PubMed

    Frausto-Reyes, C; Casillas-Peñuelas, R; Quintanar-Stephano, J L; Macías-López, E; Bujdud-Pérez, J M; Medina-Ramírez, I

    2017-05-05

    The objective of this study was to analyze by Raman and UV-Vis-NIR Spectroscopic techniques, Mexican honey from Apis Mellífera, using representative samples with different botanic origins (unifloral and multifloral) and diverse climates. Using Raman spectroscopy together with principal components analysis, the results obtained represent the possibility to use them for determination of floral origin of honey, independently of the region of sampling. For this, the effect of heat up the honey was analyzed in relation that it was possible to greatly reduce the fluorescence background in Raman spectra, which allowed the visualization of fructose and glucose peaks. Using UV-Vis-NIR, spectroscopy, a characteristic spectrum profile of transmittance was obtained for each honey type. In addition, to have an objective characterization of color, a CIE Yxy and CIE L*a*b* colorimetric register was realized for each honey type. Applying the principal component analysis and their correlation with chromaticity coordinates allowed classifying the honey samples in one plot as: cutoff wavelength, maximum transmittance, tones and lightness. The results show that it is possible to obtain a spectroscopic record of honeys with specific characteristics by reducing the effects of fluorescence.

  5. Copper(II) complexes of prion protein PEG11-tetraoctarepeat fragment: spectroscopic and voltammetric studies.

    PubMed

    Bonomo, Raffaele P; Di Natale, Giuseppe; Rizzarelli, Enrico; Tabbì, Giovanni; Vagliasindi, Laura I

    2009-04-14

    Spectroscopic (UV-Vis and EPR) and voltammetric studies have been carried out on the copper(II) complexes with the Ac-PEG11-(PHGGGWGQ)4-NH2 (L) polypeptide. In the ratios Cu : L 3 : 1 and 4 : 1, the two [Cu3(L)H(-6)] and [Cu4(L)H(-8)] complex species have been characterized at neutral pH values. All the copper atoms occupy similar coordination sites formed by imidazole, peptidic nitrogen atoms and carbonyl oxygen atoms in a square base pyramidal geometry. Voltammetric measurements on these systems point out the cooperativity in the electron transfer processes among the copper(II) sites during their reduction. NO interaction with these polynuclear copper species is characterized by the reduction of the copper sites through the formation of two different intermediate complex species. When an excess of the Ac-PEG11-(PHGGGWGQ)4-NH2 ligand is considered, frozen solution EPR parameters and UV-Vis spectroscopic data identify the [Cu(N(im))4]2+ chromophore, which does not interact with NO.

  6. 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.

  7. 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.

  8. Studying the dwarf galaxies in nearby groups of galaxies: Spectroscopic and photometric data

    NASA Astrophysics Data System (ADS)

    Hopp, U.; Vennik, J.

    2014-11-01

    Galaxy evolution by interaction-driven transformation is probably highly efficient in groups of galaxies. Dwarf galaxies with their shallow potential are expected to reflect the interaction most prominently in their observable structure. The major aim of this series of papers is to establish a data base which allows to study the impact of group interaction onto the morphology and star-forming properties of dwarf galaxies. Firstly, we present our selection rules for target groups and the morphological selection method of target dwarf member candidates. Secondly, the spectroscopic follow-up observations with the HET are presented. Thirdly, we applied own reduction methods based on adaptive filtering to derive surface photometry of the candidates. The spectroscopic follow-up indicate a dwarf identification success rate of roughly 55 %, and a group member success rate of about 33 %. A total of 17 new low surface-brightness members is presented. For all candidates, total magnitudes, colours, and light distribution parameters are derived and discussed in the context of scaling relations. We point out short comings of the SDSS standard pipeline for surface photometry for these dim objects. We conclude that our selection strategy is rather efficient to obtain a sample of dim, low surface brightness members of groups of galaxies within the Virgo super-cluster. The photometric scaling relation in these X-ray dim, rather isolated groups does not significantly differ from those of the galaxies within the local volume.

  9. Design of and Studies with a Novel One Meter Multi - Spectroscopic Telescope

    NASA Astrophysics Data System (ADS)

    Barry, Donald James

    1996-01-01

    A traditional one-meter imaging telescope costs 250,000 and weighs several tons. A novel multi -element spectroscopic telescope is described which trades imaging ability and monolithic size for low cost and weight, producing the same light gathering power at under one-tenth the cost. A complete spectroscopic facility consisting of one-meter equivalent-aperture telescope, fiber optical feed, Newtonian-Ebert spectrograph, and automated processing software has been prototyped, constructed, and placed into operation. The total cost of materials is under 85,000. A variety of science observations have been conducted with this facility including a tomographic reconstruction of the component spectra of the massive binary Plaskett's star components, a measurement of the line-profile variability of the Be stars lambda Eridani and BK Camelopardalis, and a dynamical study of the orbit of the triple star system 55 Ursae Majoris. The instrument performs well and is now in regular use as a scheduled telescope at the Georgia State University Hard Labor Creek Observatory. Improvements continue, and the telescope continues to serve a valuable role in the GSU Astronomy program's scientific programs and pedagogical mission.

  10. X-ray photoelectron and Raman spectroscopic studies of MeV proton irradiated graphite

    NASA Astrophysics Data System (ADS)

    Mathew, S.; Joseph, B.; Sekhar, B. R.; Dev, B. N.

    2008-07-01

    Poly-crystalline graphite samples were irradiated using 2.25 MeV H + ions with a fluence of 2 × 10 17 ions/cm 2. Magnetic ordering in highly oriented pyrolytic graphite samples have been reported earlier under the similar irradiation conditions [Esquinazi et al., Phys. Rev. Lett. 91 (2003) 227201]. In that study, the authors attribute the observed irradiation induced magnetic ordering to the formation of a mixed sp 2-sp 3 hybridized carbon atoms. In the present study, we report the X-ray photoelectron and Raman spectroscopic studies on pristine and irradiated samples. Irradiated samples are found to show an increased number of sp 3 hybridized carbon atoms. However, the Raman spectrum, specially the second order data, do indicate that the nature of the graphene lattice structure has been preserved in the irradiated samples. The mechanisms for the irradiation induced enhancement in sp 3 hybridization are discussed.

  11. Spectroscopic Studies on Eu{sup 3+} Doped Boro-Tellurite Glasses

    SciTech Connect

    Selvaraju, K.; Marimuthu, K.

    2011-07-15

    Eu{sup 3+} doped boro-tellurite glasses have been synthesized and its optical behavior have been studied and reported. The presence of varying tellurium dioxide content results changes in spectroscopic behavoir were explored through UV-VIS, and Luminescence spectra. The bonding parameters have been calculated based on the observed band positions of the absorption spectra. The Judd-Ofelt intensity parameters {Omega}{sub {lambda}} ({lambda} = 2, 4 and 6) have been determined through the luminescence spectra without applying any constraints and the results are presented. The Judd-Ofelt parameters have been used to determine various optical properties corresponding to {sup 5}D{sub 0}{yields}{sup 7}F{sub J}(J = 1,2,3 and 4) transitions of Eu{sup 3+} ions. The varying optical properties of the prepared glasses with the change in tellurium dioxide have been studied and compared with similar studies.

  12. 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.

  13. 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.

  14. Batch sorption and spectroscopic speciation studies of neptunium uptake by montmorillonite and corundum

    NASA Astrophysics Data System (ADS)

    Elo, O.; Müller, K.; Ikeda-Ohno, A.; Bok, F.; Scheinost, A. C.; Hölttä, P.; Huittinen, N.

    2017-02-01

    Detailed information on neptunium(V) speciation on montmorillonite and corundum surfaces was obtained by batch sorption and desorption studies combined with surface complexation modelling using the Diffuse Double-Layer (DDL) model, in situ time-resolved Attenuated Total Reflection Fourier-Transform Infrared (ATR FT-IR) and X-ray absorption (XAS) spectroscopies. The pH-dependent batch sorption studies and the spectroscopic investigations were conducted under carbonate-free conditions in 10 mM NaClO4 or 10 mM NaCl. Solid concentrations of 0.5 g/l and 5 g/l were used depending on the experiment. The neptunium(V) desorption from the two mineral surfaces was investigated at pH values ranging from 8 to 10, using the replenishment technique. Neptunium(V) was found to desorb from the mineral surface, however, the extent of desorption was dependent on the solution pH. The desorption of neptunium(V) was confirmed in the ATR FT-IR spectroscopic studies at pH 10, where all of the identified inner-sphere complexed neptunium(V), characterized by a vibrational band at 790 cm-1, was desorbed from both mineral surfaces upon flushing the mineral films with a blank electrolyte solution. In XAS investigations of neptunium(V) uptake by corundum, the obtained structural parameters confirm the formation of an inner-sphere complex adsorbed on the surface in a bidentate fashion. As the inner-sphere complexes found in the IR-studies are characterized by identical sorption bands on both corundum and montmorillonite, we tentatively assigned the neptunium(V) inner-sphere complex on montmorillonite to the same bidentate complex found on corundum in the XAS investigations. Finally, the obtained batch sorption and spectroscopic results were modelled with surface complexation modelling to explain the neptunium(V) speciation on montmorillonite over the entire investigated pH range. The modelling results show that cation exchange in the interlayer space as well as two pH-dependent surface complexes

  15. Preferential binding of fisetin to the native state of bovine serum albumin: spectroscopic and docking studies.

    PubMed

    Singha Roy, Atanu; Pandey, Nitin Kumar; Dasgupta, Swagata

    2013-04-01

    We have investigated the binding of the biologically important flavonoid fisetin with the carrier protein bovine serum albumin using multi-spectroscopic and molecular docking methods. The binding constants were found to be in the order of 10(4) M(-1) and the number of binding sites was determined as one. MALDI-TOF analyses showed that one fisetin molecule binds to a single bovine serum albumin (BSA) molecule which is also supported by fluorescence quenching studies. The negative Gibbs free energy change (∆G°) values point to a spontaneous binding process which occurs through the presence of electrostatic forces with hydrophobic association that results in a positive entropy change (+51.69 ± 1.18 J mol(-1) K(-1)). The unfolding and refolding of BSA in urea have been studied in absence and presence of fisetin using steady-state fluorescence and lifetime measurements. Urea denaturation studies indicate that fisetin is gradually released from its binding site on the protein. In the absence of urea, an increase in temperature that causes denaturation of the protein results in the release of fisetin from its bound state indicating that fisetin binds only to the native state of the protein. The circular dichroism (CD) and Fourier transform infrared (FTIR) spectroscopic studies showed an increase in % α-helix content of BSA after binding with fisetin. Site marker displacement studies in accordance with the molecular docking results suggested that fisetin binds in close proximity of the hydrophobic cavity in site 1 (subdomain IIA) of the protein. The PEARLS (Program of Energetic Analysis of Receptor Ligand System) has been used to estimate the interaction energy of fisetin with BSA and the results are in good correlation with the experimental findings.

  16. Interaction between serum albumins and sonochemically synthesized cadmium sulphide nanoparticles: a spectroscopic study

    NASA Astrophysics Data System (ADS)

    Naveenraj, Selvaraj; Asiri, Abdullah M.; Anandan, Sambandam

    2013-05-01

    Cadmium Sulphide nanoparticles approximately 5-10 nm in size range were synthesized by sonochemical technique, which follows acoustic cavitation phenomenon and generates nanoparticles with a smaller size range and higher surface area. The in vitro binding interaction of these sonochemically synthesized CdS nanoparticles with serum albumins (SA) were investigated using UV-Vis absorption, fluorescence and circular dichroism (CD) spectroscopic techniques since CdS nanoparticles has biological applications such as cellular labelling and deep-tissue imaging. UV-Vis absorption and fluorescence studies confirm that CdS nanoparticles bind with SA through ground state complex formation (static quenching mechanism). The results suggest that sonochemically synthesized CdS nanoparticles interact with HSA more than that of BSA and these nanoparticles can be easily transported and rapidly released to the targets by serum albumins. CD studies confirmed the conformational change of serum albumins on the interaction of CdS nanoparticles.

  17. Synthesis, Spectroscopic, ac Conductivity and Thermal Studies on Co(III) Acetylacetonate-Iodine Complex

    NASA Astrophysics Data System (ADS)

    Hashem, H. A.; Refat, M. S.

    A spectrophotometric study of 1:1 donor-acceptor complex, cobalt (III) acetylacetonate (donor) and iodine (σ-acceptor) has been preformed. The equilibrium constants, (K) and the absorpitivity (ɛ) for the formation of the iodine complex have been calculated. The predicted structure of the solid triiodide charge-transfer complex reported in this study is further supported by thermal, far and mid infrared spectroscopic measurements. Electron transfer from Co (acac = 2, 4-pentanedionate)3 to iodine leads to the formation of an organic semiconductor with the formula of [Co(acac)3]_2 I+. I3-. The kinetic parameters (nonisothermal method) for their decomposition have been evaluated by graphical methods using the equations of Freeman-Carroll (FC), Horowitz-Metzger (HM) and Coats-Redfern (CR). The ac conductivity and dielectric properties of [Co(acac)3]_2 I+. I3- have been measured over the frequency 50-106 Hz at temperature 298 K.

  18. 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.

  19. Defect study in ZnO related structures—A multi-spectroscopic approach

    NASA Astrophysics Data System (ADS)

    Ling, C. C.; Cheung, C. K.; Gu, Q. L.; Dai, X. M.; Xu, S. J.; Zhu, C. Y.; Luo, J. M.; Zhu, C. Y.; Tam, K. H.; Djurišić, A. B.; Beling, C. D.; Fung, S.; Lu, L. W.; Brauer, G.; Anwand, W.; Skorupa, W.; Ong, H. C.

    2008-10-01

    ZnO has attracted a great deal of attention in recent years because of its potential applications for fabricating optoelectronic devices. Using a multi-spectroscopic approach including positron annihilation spectroscopy (PAS), deep level transient spectroscopy (DLTS), photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS), we have studied the two observed phenomena from ZnO related structures. They namely included the H 2O 2 pre-treatment induced ohmic to rectifying contact conversion on Au/ n-ZnO contact and the p-type doping by nitrogen ion implantation. The aim of the studies was to offering comprehensive views as to how the defects influenced the structures electrical and optical properties of the structures. It was also shown that PAS measurement using the monoenergetic positron beam could offer valuable information of vacancy type defects in the vertical ZnO nanorod array structure.

  20. Electrochemical and spectroscopic studies of the oxidation mechanism of the herbicide propanil.

    PubMed

    Garrido, E M; Lima, J L F C; Delerue-Matos, C; Borges, F; Silva, A M S; Piedade, J A P; Oliveira Brett, A M

    2003-02-12

    Electrochemical oxidation of propanil in deuterated solutions was studied by cyclic, differential pulse, and square wave voltammetry using a glassy carbon microelectrode. The oxidation of propanil in deuterated acid solutions occurs at the nitrogen atom of the amide at a potential of +1.15 V vs Ag/AgCl. It was also found that, under the experimental conditions used, protonation at the oxygen atom of propanil occurs, leading to the appearance of another species in solution which oxidizes at +0.60 V. The anodic peak found at +0.79 V vs Ag/AgCl in deuterated basic solutions is related to the presence of an anionic species in which a negative charge is on the nitrogen atom. The electrochemical data were confirmed by the identification of all the species formed in acidic and basic deuterated solutions by means of NMR spectroscopy. The results are supported by electrochemical and spectroscopic studies of acetanilide in deuterated solutions.

  1. Accurate molecular structure and spectroscopic properties for nucleobases: A combined computational - microwave investigation of 2-thiouracil as a case study

    PubMed Central

    Puzzarini, Cristina; Biczysko, Malgorzata; Barone, Vincenzo; Peña, Isabel; Cabezas, Carlos; Alonso, José L.

    2015-01-01

    The computational composite scheme purposely set up for accurately describing the electronic structure and spectroscopic properties of small biomolecules has been applied to the first study of the rotational spectrum of 2-thiouracil. The experimental investigation was made possible thanks to the combination of the laser ablation technique with Fourier Transform Microwave spectrometers. The joint experimental – computational study allowed us to determine accurate molecular structure and spectroscopic properties for the title molecule, but more important, it demonstrates a reliable approach for the accurate investigation of isolated small biomolecules. PMID:24002739

  2. SPECTROSCOPIC STUDIES OF THE ANAEROBIC ENZYME-SUBSTRATE COMPLEX OF CATECHOL 1,2-DIOXYGENASE

    PubMed Central

    Horsman, Geoff P.; Jirasek, Andrew; Vaillancourt, Frédéric H.; Barbosa, Christopher J.; Jarzecki, Andrzej A.; Xu, Changliang; Mekmouche, Yasmina; Spiro, Thomas G.; Lipscomb, John D.; Blades, Michael W.; Turner, Robin F.B.; Eltis, Lindsay D.

    2008-01-01

    The basis of the respective regiospecificities of intradiol and extradiol dioxygenase is poorly understood and may be linked to the protonation state of the bidentate-bound catechol in the enzyme:substrate complex. Previous ultraviolet resonance Raman (UVRR) and UV-visible (UV-vis) difference spectroscopic studies demonstrated that in extradiol dioxygenases, the catechol is bound to the Fe(II) as a monoanion. In this study, we use the same approaches to demonstrate that in catechol 1,2-dioxygenase (C12O), an intradiol enzyme, the catechol binds to the Fe(III) as a dianion. Specifically, features at 290 nm and 1550 cm−1 in the UV-vis and UVRR difference spectra, respectively, are assigned to dianionic catechol based on spectra of the model compound, ferric tris(catecholate). The UVRR spectroscopic band assignments are corroborated by density functional theory (DFT) calculations. In addition, negative features at 240 nm in UV-vis difference spectra and at 1600, 1210, and 1175 cm−1 in UVRR difference spectra match those of a tyrosinate model compound, consistent with protonation of the axial tyrosinate ligand when it is displaced from the ferric ion coordination sphere upon substrate binding. The DFT calculations ascribe the asymmetry of the bound dianionic substrate to the trans donor effect of an equatorially ligated tyrosinate ligand. In addition, the computations suggest that trans donation from the tyrosinate ligand may facilitate charge-transfer from the substrate to yield the iron-bound semiquinone transition state, which is capable of reacting with dioxygen. In illustrating the importance of ligand trans effects in a biological system, the current study demonstrates the power of combining difference UVRR and optical spectroscopies to probe metal ligation in solution. PMID:16316234

  3. 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.

  4. 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.

  5. 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.

  6. Thermal dependence of optical properties of silver thin films studied by spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Sundari, S. Tripura; Dash, S.; Tyagi, A. K.

    2012-06-01

    The thermal dependence of the dielectric constants of silver thin films were investigated between 300 K and 650 K by spectroscopic ellipsometer in the energy range 1.5 to 5 eV. The studies showed an increase in the imaginary part (ɛ2) of the dielectric function, a shift of ˜300 meV in the onset of the main absorption (L3-L2'(EF)), appearance of additional absorption above 500 K which is attributed to (L2'- L1) and increased broadening of the absorption spectra owing to smearing of Fermi level. It was found that the unscreened plasma frequency ωpu associated with resonant oscillations of conduction electrons increased while the relaxation time decreased with increase in temperature.

  7. Raman spectroscopic study of high-pressure behavior of Ag3[Co(CN)6

    NASA Astrophysics Data System (ADS)

    Rao, Rekha; Achary, S. N.; Tyagi, A. K.; Sakuntala, T.

    2011-08-01

    In situ Raman spectroscopic studies have been carried out on Ag3[Co(CN)6] at high pressures up to 16 GPa. From the pressure dependence of the Raman frequencies, the mode Grüneisen parameters in the trigonal and the monoclinic phases are obtained. Besides the reported trigonal-to-monoclinic transition at 0.2 GPa, it is observed that the compound shows pressure-induced amorphization above 13 GPa. The recovered sample shows features characteristic of amorphous carbon nitride, indicating the decomposition of the parent compound in the pressure-reducing cycle. Temperature dependence of the mode frequencies over the range 80-290 K is also investigated, from which the modes that are more anharmonic than other modes are identified.

  8. 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.

  9. Growth of vacuum evaporated ultraporous silicon studied with spectroscopic ellipsometry and scanning electron microscopy

    NASA Astrophysics Data System (ADS)

    Kaminska, Kate; Amassian, Aram; Martinu, Ludvik; Robbie, Kevin

    2005-01-01

    Using a combination of variable-angle spectroscopic ellipsometry and scanning electron microscopy, we investigated the scaling behavior of uniaxially anisotropic, ultraporous silicon manufactured with glancing angle deposition. We found that both the diameter of the nanocolumns and the spacing between them increase with film thickness according to a power-law relationship consistent with self-affine fractal growth. An ellipsometric model is proposed to fit the optical properties of the anisotropic silicon films employing an effective medium approximation mixture of Tauc-Lorentz oscillator and void. This study shows that the optical response of silicon films made at glancing incidence differs significantly from that of amorphous silicon prepared by other methods due to highly oriented nanocolumn formation and power-law scaling.

  10. Wrapping Together Galactic Archaeology and Interstellar Medium Studies in Large Spectroscopic Surveys

    NASA Astrophysics Data System (ADS)

    Kos, J.

    2016-10-01

    The cold interstellar medium (ISM) in our galaxy is usually observed at wavelengths other than optical. But optical spectroscopic surveys of stars give unprecedented information that is valuable also for ISM studies because they cover millions of lines-of-sight penetrating regions in and out of the Galactic plane that most all-sky surveys. Big advantages are distances to observed stars from which we infer distances to clumps of the ISM. The ISM is detected as scarce absorptions of several atoms and simple molecules and also as diffuse interstellar bands (DIBs), weak but numerous absorption features at visible and near IR wavelengths. With the enormous amount of information the surveys provide we can start doing galactic archaeology from the ISM point of view. Even though the principles are very different for star and gas dynamics, the starting points are the same. Here we present some results that are the first steps toward the galactic archaeology of the ISM.

  11. Spectroscopic studies of UV irradiated erythrosine B thin films prepared by spin coating technique.

    PubMed

    Zeyada, H M; El-Mallah, H M; Atwee, T; El-Damhogi, D G

    2017-05-15

    The spectroscopic studies of erythrosine B thin films manufactured by the spin coating technique have been presented. The spectra of infrared absorption allow characterization of vibrational modes for erythrosine B in powder form, pristine and UV irradiated thin films. The absorption spectra recorded in UV-vis-NIR for pristine films of erythrosine B display two main bands. UV irradiation on erythrosine B films decreased absorbance over the spectra. Indirect allowed transition with optical energy gap of 2.57eV is observed in pristine films. UV irradiation introduced structural defects and decreased optical band gap. Some of the optical absorption parameters and their relation to UV irradiation times, namely molar extinction coefficient (ε), electronic dipole strength (q(2)), and oscillator strength (f), of the principal optical transitions have also been evaluated.

  12. Biophysical influence of coumarin 35 on bovine serum albumin: Spectroscopic study

    NASA Astrophysics Data System (ADS)

    Bayraktutan, Tuğba; Onganer, Yavuz

    2017-01-01

    The binding mechanism and protein-fluorescence probe interactions between bovine serum albumin (BSA) and coumarin 35 (C35) was investigated by using UV-Vis absorption and fluorescence spectroscopies since they remain major research topics in biophysics. The spectroscopic data indicated that a fluorescence quenching process for BSA-C35 system was occurred. The fluorescence quenching processes were analyzed using Stern-Volmer method. In this regard, Stern-Volmer quenching constants (KSV) and binding constants were calculated at different temperatures. The distance r between BSA (donor) and C35 (acceptor) was determined by exploiting fluorescence resonance energy transfer (FRET) method. Synchronous fluorescence spectra were also studied to observe information about conformational changes. Moreover, thermodynamics parameters were calculated for better understanding of interactions and conformational changes of the system.

  13. 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.

  14. FTIR spectroscopic studies of lipid dynamics in phytosphingosine ceramide models of the stratum corneum lipid matrix.

    PubMed

    Rerek, Mark E; Van Wyck, Dina; Mendelsohn, Richard; Moore, David J

    2005-03-01

    IR spectroscopic studies are reported for N-stearyl-D-erythro-phytosphingosine (Cer NP) and N-stearyl-2-hydroxy-D-erythro-phytosphingosine (Cer AP) in a hydrated model of the skin lipid barrier comprised of equimolar mixtures of each ceramide with cholesterol and d(35)-stearic acid. Examination of the methylene stretching, rocking and bending modes reveal some rotational freedom and hexagonal packing in both the ceramide and stearic acid chains. Analysis of the acid carbonyl stretch and the ceramide Amide I modes show both shift to higher frequencies, indicating weaker hydrogen bonding, in the mixed systems compared to the pure materials. For both systems, the fatty acid chain disordering temperatures are significantly increased from those of the pure acids. The observed behaviors of these phytosphingosine ceramide systems are fundamentally different from the previously reported analogous sphingosine ceramide systems. The implications of these observations for lipid organization in the stratum corneum are briefly discussed.

  15. 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.

  16. 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

  17. 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.

  18. Study of biological reaction in cancer cell with spectroscopic imaging ellipsometry

    NASA Astrophysics Data System (ADS)

    Chen, Yu-Da; Hsu, Hao Yun; Khaleel, Mai Ibrahim; Chang, Yia-Chung; Wu, Chien-Hsun; Wu, Han-Chung

    2016-09-01

    We present experimental studies of live cancer cells via microscopic imaging ellipsometry (MIE). The Rotating Compensator Ellipsometry (RCE) is used for our measurements. Ellipsometry spectra with signals integrated over a 20μm×20μm area in visible range (450nm to 750nm) are obtained with the Optrel MULTISKOP system for both specular reflection and off-specular scattering. The microscopic ellipsometry (ME) images at a few fixed wavelengths within the same range were also analyzed. Dielectric constants for glass slide, culture fluid, and glass cover plate were firstly characterized by spectroscopic ellipsometry measurements, which can be used in the simulation for MIE measurements of cancer cells embedded in the culture fluid and sandwiched between a glass slide and cover plate. The measured ME spectra and images of cancer cells before and after medicine injection are measured and analyzed.

  19. 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.

  20. Photometric and spectroscopic study of the new FUor star V2493 Cyg

    NASA Astrophysics Data System (ADS)

    Semkov, Evgeni H.; Peneva, Stoyanka P.; Ibryamov, Sunay I.

    2017-01-01

    The recent results from photometric and spectroscopic study of the FUor star V2493 Cyg (HBC 722) are presented in the paper. The outburst of V2493 Cyg was registered during the summer of 2010 before the brightness of the star reached the maximum value. V2493 Cyg is the first FUor object, whose outburst was observed from its very beginning in all spectral ranges. The recent photometric data show that the star keeps its maximum brightness during the period September 2013 - Ocober 2016 and the recorded amplitude of the outburst is ΔV=5.1 mag. Consequently, the outburst of V2493 Cyg lasts for more than six years. Our spectral observations showed strong variability in the profiles and the intensity of emission lines especially for Hα line. We expect that the interest in this object will increase in the coming years and the results will help to explore the nature of young stars.

  1. Plasma-enhanced atomic layer deposition of titanium oxynitrides films: A comparative spectroscopic and electrical study

    SciTech Connect

    Sowińska, Małgorzata Henkel, Karsten; Schmeißer, Dieter; Kärkkänen, Irina; Schneidewind, Jessica; Naumann, Franziska; Gruska, Bernd; Gargouri, Hassan

    2016-01-15

    The process parameters' impact of the plasma-enhanced atomic layer deposition (PE-ALD) method on the oxygen to nitrogen (O/N) ratio in titanium oxynitride (TiO{sub x}N{sub y}) films was studied. Titanium(IV)isopropoxide in combination with NH{sub 3} plasma and tetrakis(dimethylamino)titanium by applying N{sub 2} plasma processes were investigated. Samples were characterized by the in situ spectroscopic ellipsometry, x-ray photoelectron spectroscopy, and electrical characterization (current–voltage: I-V and capacitance–voltage: C-V) methods. The O/N ratio in the TiO{sub x}N{sub y} films is found to be very sensitive for their electric properties such as conductivity, dielectric breakdown, and permittivity. Our results indicate that these PE-ALD film properties can be tuned, via the O/N ratio, by the selection of the process parameters and precursor/coreactant combination.

  2. 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.

  3. Molecular interactions of flavonoids to pepsin: Insights from spectroscopic and molecular docking studies.

    PubMed

    Zeng, Hua-Jin; Yang, Ran; Liang, Huili; Qu, Ling-Bo

    2015-01-01

    In the work described on this paper, the inhibitory effect of 10 flavonoids on pepsin and the interactions between them were investigated by a combination of spectroscopic and molecular docking methods. The results indicated that all flavonoids could bind with pepsin to form flavonoid-pepsin complexes. The binding parameters obtained from the data at different temperatures revealed that flavonoids could spontaneously interact with pepsin mainly through electrostatic forces and hydrophobic interactions with one binding site. According to synchronous and three-dimensional fluorescence spectra and molecular docking results, all flavonoids bound directly into the enzyme cavity site and the binding influenced the microenvironment and conformation of the pepsin activity site which resulted in the reduced enzyme activity. The present study provides direct evidence at a molecular level to understand the mechanism of digestion caused by flavonoids.

  4. 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.

  5. Fe-complex of a tetraamido macrocyclic ligand: Spectroscopic characterization and catalytic oxidation studies

    NASA Astrophysics Data System (ADS)

    Sullivan, Shane Z.; Ghosh, Anindya; Biris, Alexandru S.; Pulla, Sharon; Brezden, Anna M.; Collom, Samulel L.; Woods, Ross M.; Munshi, Pradip; Schnackenberg, Laura; Pierce, Brad S.; Kannarpady, Ganesh K.

    2010-10-01

    This work presents the spectroscopic characterization and reaction studies of a Fe III-complex (2) of a tetraamido macrocyclic ligand (1, 15,15-dimethyl-5,8,13,17-tetrahydro-5,8,13,17-tetraaza-dibenzo[a,g]cyclotridecene-6,7,14,16-tetraone). 2 was characterized primarily by means of EPR. In agreement with the magnetic moment ( μeff = 3.87 BM), EPR spectroscopy of 2 shows signals consistent with S = 3/2 intermediate-spin ferric-iron. Besides EPR, mass spectrometry, UV/vis spectroscopy and cyclic voltammetry were used to further characterize 2. 2 is soluble in water and activates hydrogen peroxide under ambient conditions. 2 catalytically bleaches dyes, pulp and paper effluents and oxidizes several amines to their corresponding N-oxides with high turnover number and good yields.

  6. Molecular spectroscopic study on the interaction of tetracyclines with serum albumins

    NASA Astrophysics Data System (ADS)

    Bi, Shuyun; Song, Daqian; Tian, Yuan; Zhou, Xin; Liu, Zhongying; Zhang, Hanqi

    2005-02-01

    A molecular spectroscopic investigation of the interaction between tetracyclines antibiotics and human serum albumin or bovine serum albumin was reported. The influences of some metal ions on the interaction were also studied. When tetracyclines drugs were added into the solution containing serum albumins, the fluorescence intensity of serum albumins decreased with the increasing of the drugs concentrations, which is due to the formation of new non-fluorescence complexes of drug-serum albumin. The tetracyclines acted as quenchers and quenched the fluorescence of the serum albumins. The binding constants and the number of the binding sites of the reaction of tetracyclines and serum albumins were obtained. The main sorts of acting force between the drugs and serum albumins were found and the action distances and the energy transfer efficiencies between donor-acceptor were calculated based on the Föster energy transference.

  7. Raman spectroscopic study on the excystation process in a single unicellular organism amoeba (Acanthamoeba polyphaga).

    PubMed

    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.

  8. 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.

  9. Linear and nonlinear impedance spectroscopy for the study of electrode/solution interfaces

    NASA Astrophysics Data System (ADS)

    Peck, John R.

    We develop and demonstrate techniques to produce stable, electrically nonlinear conditions at electrode/solution interfaces in the absence of charge-transfer (faradaic) reactions for application to electrochemical biosensors. We introduce random-pulse AC voltammetry for the study of interfacial nonlinearities, and apply the technique to studies of pH-active self-assembled monolayers (SAMs). These studies show that interfacial nonlinearities can be an order of magnitude more sensitive to the charge state of the surface than its linear properties. Furthermore, the use of these nonlinearities will allow isolation of the interface from a linear background due to fixture or equipment parasitics---a background that becomes severe as electrode sizes shrink for microarray applications. We make arguments for the use of radio frequencies in these systems, and present techniques to extend the use of conventional electrochemical equipment to these frequencies. Finally, we simulate the use of a slot antenna resonator for the detection of DNA hybridization at GHz frequencies, and find that shifts in the system resonances upon hybridization should be easily seen if the high frequency fields are confined to the surface region.

  10. Spectroscopic and dynamical studies of highly energized small polyatomic molecules. Technical progress report, July 1, 1993--October 31, 1994

    SciTech Connect

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

    1995-02-01

    This is a progress report on a project to spectroscopically study small polyatomic molecules which are highly excited. The authors describe work on acetylene (HCCH) and HCO. Their work involves dispersed fluorescence spectroscopy, and the development and application of superpolyad models for studying intramolecular vibrational redistribution.

  11. Electrochemical impedance spectroscopy study of high-palladium dental alloys. Part I: behavior at open-circuit potential.

    PubMed

    Sun, D; Monaghan, P; Brantley, W A; Johnston, W M

    2002-05-01

    Electrochemical impedance spectroscopy (EIS) was used to study the in vitro corrosion of three representative high-palladium alloys and a gold-palladium alloy for comparison. The corrosion resistances (measured as the charge transfer resistance R(CT) from an equivalent circuit) of the high-palladium alloys and the gold-palladium alloy were comparable in simulated body fluid and oral environments, and under simulated dental plaque. The great similarity in corrosion behavior for the three high-palladium alloys is largely attributed to their substantial palladium content and passivity in the laboratory test media, and possibly to their similar structure at the submicron level. Differences in composition and microstructure at the micron level and greater, including the effects of heat treatment simulating the firing cycles for dental porcelain, do not have noteworthy effects on the in vitro corrosion of the three high-palladium alloys. Good accuracy and convenience of extracting corrosion characteristics from equivalent circuit modeling, along with the capability of providing intrinsic information about the corrosion mechanism, enable EIS to be an excellent alternative method to conventional potentiodynamic polarization for evaluating the corrosion behavior of noble dental alloys.

  12. Electrochemical Impedance Spectroscopy study in micro-grain structured amorphous silicon anodes for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Paloukis, Fotis; Elmasides, Costas; Farmakis, Filippos; Selinis, Petros; Neophytides, Stylianos G.; Georgoulas, Nikolaos

    2016-11-01

    In this paper, a study of the lithiation mechanism of micro-grain structured silicon anode is presented. Micro-grain amorphous silicon was deposited on special copper foil and it is shown that after several decades of galvanostatic cycles, it preserves its granular nature with minor degradation. In order to shed light on the lithiation mechanisms of the micro-grain silicon, Electrochemical Impedance Spectroscopy (EIS) was conducted on silicon half-cells at various State-of-Charge (SoC) and various discharging current values and the Solid-Electrolyte Interphase (SEI) RSEI and polarization resistance Rpol were determined. Results reveal that Rpol highly increases for cell voltages lower than 0.2 V and it strongly depends on the discharging C-rate. From X-ray Photoelectron Spectroscopy (XPS) measurements combined with surface sputtering, the existence of a LixSiyOz interlayer between SEI and silicon is confirmed, which is believed to play an important role to the lithium kinetics. Finally, combining our results, a lithiation mechanism of the micro-grain silicon anode is proposed.

  13. Raman and electrochemical impedance studies of sol-gel titanium oxide and single walled carbon nanotubes composite films.

    PubMed

    Rincón, M E; Trujillo-Camacho, M E; Miranda-Hernández, M; Cuentas-Gallegos, A K; Orozco, G

    2007-01-01

    Titanium oxide grown by a sol-gel route on single-walled carbon nanotubes was studied by Raman and Electrochemical Impedance techniques and compared with mixtures obtained by mechanical grinding. In spite of the superior dispersion of single-walled carbon nanotubes bundles in sol-gel composites, the lost of the small-diameter carbon nanotubes in the oxidizing sol-gel bath was inferred from their Raman spectra and the lower capacitive current of the voltammograms in 0.1 M H2SO4. We proposed proton electrosorption as the main charge storage mechanism for sol-gel composites, favoured by the hydroxylation and n-type conductivity of the oxide, while electrodes based on mixtures were dominated by double-layer charging, developing some pseudocapacitance with potential cycling due to the reversible oxidation of carbon nanotubes. Comparsion with TiO2/Carbon Blacks composites shows the effective role of single-walled carbon nanotubes as templates to control the mesoporous nature of sol-gel composite electrodes.

  14. 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

  15. 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.

  16. Molecular hydraulic properties of montmorillonite: a polarized fourier transform infrared spectroscopic study.

    PubMed

    Amarasinghe, Priyanthi M; Katti, Kalpana S; Katti, Dinesh R

    2008-12-01

    Understanding the rates at which fluid flows into clay interlayers at the molecular level is fundamental to designing an effective clay barrier system. In this work, molecular interactions at the Na-montmorillonite (MMT)-water interface, emphasizing the flow properties of the clay interlayer, have been studied at the molecular and nanoscale level using polarized Fourier transform infrared (FT-IR) spectroscopic and X-ray diffraction (XRD) techniques. Clay-water slurries were smeared on inert gold-coated metal substrates for FT-IR experiments and slurries were smeared on quartz plates for XRD experiments. By analyzing the O-H stretching and H-O-H bending vibrations in clay slurries, it was concluded that the molecular behavior of interlayer water is significantly different from the molecular behavior of bulk water. With increasing clay-water interaction time, it was also seen that the Si-O stretching bands of clay are being significantly altered by the water molecules in the interlayer. Using these spectroscopic techniques we have estimated the time required for water to flow into the clay interlayer. Further, by analyzing the particle size of the clay using atomic force microscopy (AFM) imaging, we were able to estimate the flow velocity of the water in the clay interlayer. This velocity is found to be 3.23 x 10(-9) cm/s. This flow velocity was found to be of the same order of magnitude as the hydraulic conductivity of smectite-type clay reported elsewhere. Also described in this work is the correct positioning of the Si-O out-of-plane vibration band of MMT at the two-layer saturation level in the interlayer. This band was only observed in p-polarized spectra at 1211 cm(-1). Thus, we attribute this band to the Si-O out-of-plane vibration band.

  17. 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.

  18. Electrical Impedance Tomography of Breast Cancer

    DTIC Science & Technology

    2005-06-01

    SUBJECT TERMS Diagnosis of Metastatic Cancer, Magnetic Resonance Imaging, Electrical Impedance Imaging, Electrical Impedance Scanning, MRI current...1) To develop and optimize the necessary hardware and software for Magnetic Resonance Electrical Impedance Tomography (MREIT) and interface it with...of Magnetic Resonance in Medicine (ISMRM) conference and included in the appendix for reference. 2.2.2. Second Year: A series of new phantom studies

  19. The spectroscopic study of simple polyatomic molecules by synchrotron and laser irradiation

    NASA Astrophysics Data System (ADS)

    Kaminski, Lech

    This thesis describes the spectroscopic study of simple poly-atomic molecules, for example NO and Cl2O by UV radiation derived from synchrotron and laser sources. Synchrotron studies were carried out at the Daresbury Laboratory Synchrotron Radiation Source, and the laser studies performed at University College London. The thesis is composed of six chapters. The first chapter discusses molecular structure; UV absorption of photons by simple molecules and describes the modern techniques of Resonance Enhanced Multi Photon Ionisation (REMPI) and Laser Induced Fluorescence (LIF) processes. Chapter two describes the apparatus and the experimental techniques developed during this project at the Daresbury Laboratory Synchrotron Radiation Source. Details are given on the different photoabsorption cells that were built and used, as well as details of synthesis plants used to create short lived molecules of particular importance to atmospheric chemistry, for example N2O5. Chapter three gives a full description of the laser system constructed to study REMPI and LIF processes. The data collection and experimental methodology of the final experimental configuration to study REMPI phenomena is also detailed. Chapter four describes the results obtained by photoabsorption studies for the atmospheric nitrogen and chlorine oxides (Cl2O, N2O5 and ClONO2) Chapter five gives an overview of the results obtained by photoabsorption studies of Polycyclic Aromatic Hydrocarbons. Chapter six presents conclusions of the current work and discusses future experiments that may be undertaken in the apparatus developed during this PhD program.

  20. Spectroscopic and molecular docking studies on the interaction of troxerutin with DNA.

    PubMed

    Subastri, A; Ramamurthy, C H; Suyavaran, A; Mareeswaran, R; Lokeswara Rao, P; Harikrishna, M; Suresh Kumar, M; Sujatha, V; Thirunavukkarasu, C

    2015-01-01

    Troxerutin (TXER) is a derivative of naturally occurring bioflavonoid rutin. It possesses different biological activities in rising clinical world. The biological activity possessed by most of the drugs mainly targets on macromolecules. Hence, in the current study we have examined the interaction mechanism of TXER with calf thymus DNA (CT-DNA) by using various spectroscopic methods, isothermal titration calorimetry (ITC) and molecular docking studies. Further, DNA cleavage study was carried out to find the DNA protection activity of TXER. UV-absorption and emission spectroscopy showed low binding constant values via groove binding. Circular dichroism study indicates that TXER does not modify native B-form of DNA, and it retains the native B-conformation. Furthermore, no effective positive potential peak shift was observed in TXER-DNA complex during electrochemical analysis by which it represents an interaction of TXER with DNA through groove binding. Molecular docking study showed thymine guanine based interaction with docking score -7.09 kcal/mol. This result was compared to experimental ITC value. The DNA cleavage study illustrates that TXER does not cause any DNA damage as well as TXER showed DNA protection against hydroxyl radical induced DNA damage. From this study, we conclude that TXER interacts with DNA by fashion of groove binding.

  1. Anisotropic Artificial Impedance Surfaces

    NASA Astrophysics Data System (ADS)

    Quarfoth, Ryan Gordon

    Anisotropic artificial impedance surfaces are a group of planar materials that can be modeled by the tensor impedance boundary condition. This boundary condition relates the electric and magnetic field components on a surface using a 2x2 tensor. The advantage of using the tensor impedance boundary condition, and by extension anisotropic artificial impedance surfaces, is that the method allows large and complex structures to be modeled quickly and accurately using a planar boundary condition. This thesis presents the theory of anisotropic impedance surfaces and multiple applications. Anisotropic impedance surfaces are a generalization of scalar impedance surfaces. Unlike the scalar version, anisotropic impedance surfaces have material properties that are dependent on the polarization and wave vector of electromagnetic radiation that interacts with the surface. This allows anisotropic impedance surfaces to be used for applications that scalar surfaces cannot achieve. Three of these applications are presented in this thesis. The first is an anisotropic surface wave waveguide which allows propagation in one direction, but passes radiation in the orthogonal direction without reflection. The second application is a surface wave beam shifter which splits a surface wave beam in two directions and reduces the scattering from an object placed on the surface. The third application is a patterned surface which can alter the scattered radiation pattern of a rectangular shape. For each application, anisotropic impedance surfaces are constructed using periodic unit cells. These unit cells are designed to give the desired surface impedance characteristics by modifying a patterned metallic patch on a grounded dielectric substrate. Multiple unit cell geometries are analyzed in order to find the setup with the best performance in terms of impedance characteristics and frequency bandwidth.

  2. How Zn can impede Cu detoxification by chelating agents in Alzheimer's disease: a proof-of-concept study.

    PubMed

    Conte-Daban, Amandine; Day, Adam; Faller, Peter; Hureau, Christelle

    2016-10-04

    The role of Cu and Zn ions in Alzheimer's disease is linked to the consequences of their coordination to the amyloid-β (Aβ) peptide, i.e. to the modulation of Aβ aggregation and to the production of Reactive Oxygen Species (ROS), two central events of the so-called amyloid cascade. The role of both ions in Aβ aggregation is still controversial. Conversely the higher toxicity of the redox competent Cu ions (compared to the redox inert Zn ions) in ROS production is acknowledged. Thus the Cu ions can be considered as the main therapeutic target. Because Zn ions are present in higher quantity than Cu ions in the synaptic cleft, they can prevent detoxification of Cu by chelators unless they have an unusually high Cu over Zn selectivity. We describe a proof-of-concept study where the role of Zn on the metal swap reaction between two prototypical ligands and the Cu(Aβ) species has been investigated by several complementary spectroscopic techniques (UV-Vis, EPR and XANES). The first ligand has a higher Cu over Zn selectivity relative to the one of Aβ peptide while the second one exhibits a classical Cu over Zn selectivity. How Zn impacts the effect of the ligands on Cu-induced ROS production and Aβ aggregation is also reported.

  3. [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.

  4. Structural and spectroscopic studies on Er3+ doped boro-tellurite glasses

    NASA Astrophysics Data System (ADS)

    Selvaraju, K.; Marimuthu, K.

    2012-04-01

    Er3+ doped boro-tellurite glasses with the chemical composition (69-x)B2O3-xTeO2-15MgO-15K2O-1Er2O3 (where x=0, 10, 20, 30 and 40 wt%) have been prepared and their structural and spectroscopic behavior were studied and reported. The varying tellurium dioxide content in the host matrix that results, changes in structural and spectroscopic behavior around Er3+ ions are explored through XRD, FTIR, UV-VIS-NIR and luminescence measurements. The XRD pattern confirms the amorphous nature of the prepared glasses and the FTIR spectra explore the fundamental groups and the local structural units in the prepared boro-tellurite glasses. The bonding parameters (βbar and δ) have been calculated from the observed band positions of the absorption spectra to claim the ionic/covalent nature of the prepared glasses. The Judd-Ofelt (JO) intensity parameters Ωλ (λ=2, 4 and 6) were determined through experimental and calculated oscillator strengths obtained from the absorption spectra and their results are studied and compared with reported literature. The variation in the JO parameters Ωλ (λ=2, 4 and 6) with the change in chemical composition have been discussed in detail. The JO parameters have also been used to derive the important radiative properties like transition probability (A), branching ratio (βR) and peak stimulated emission cross-section (σPE) for the excited state transitions 2H9/2→4I15/2 and 2H11/2 and 4S3/2→4I15/2 of the Er3+ ions and the results were studied and reported. Using Davis and Mott theory, optical band gap energy (Eopt) values for the direct and indirect allowed transitions have been calculated and discussed along with the Urbach energy values for the prepared Er3+ doped boro-tellurite glasses in the present study. The optical properties of the prepared glasses with the change in tellurium dioxide have been studied and compared with similar results.

  5. 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.

  6. Static and time-resolved spectroscopic studies of low-symmetry Ru(II) polypyridyl complexes

    SciTech Connect

    Curtright, A.E.; McCusker, J.K.

    1999-09-02

    The spectroscopic and electrochemical properties of a series of four Ru{sup II} polypyridyl complexes are reported. Compounds of the form [Ru(dmb){sub x}(dea){sub 3{minus}x}]{sup 2+} (x = 0--3), where dmb is 4,4{prime}-dimethyl-2,2{prime}-bipyridine and dea is 4,4{prime}-bis(diethylamino)-2,2{prime}-bipyridine, have been prepared and studied using static and time-resolved electronic and vibrational spectroscopies as a prelude to femtosecond spectroscopic studies of excited-state dynamics. Static electronic spectra in CH{sub 3}CN solution reveal a systematic shift of the MLCT absorption envelope from a maximum of 458 nm in the case of [Ru(dmb){sub 3}]{sup 2+} to 518 nm for [Ru(dea){sub 3}]{sup 2+} with successive substitutions of dea for dmb, suggesting a dea-based chromophore as the lowest-energy species. However, analysis of static and time-resolved emission data indicates an energy gap ordering of [Ru(dmb){sub 3}]{sup 2+} > [Ru(dmb){sub 2}(dea)]{sup 2+} > [Ru(dea){sub 3}]{sup 2+} > [Ru(dmb)(DEA){sub 2}]{sup 2+}, at variance with the electronic structures inferred from the absorption spectra. Nanosecond time-resolved electronic absorption and time-resolved step-scan infrared data are used to resolve this apparent conflict and confirm localization of the long-lived {sup 3}MLCT state on dmb in all three complexes where this ligand is present, thus making the dea-based excited state unique to [Ru(dea){sub 3}]{sup 2+}. Electrochemical studies further reveal the origin of this result, where a strong influence of the dea ligand on the oxidative Ru{sup II/III} couple, due to {pi} donation from the diethylamino substituent, is observed. The electronic absorption spectra are then reexamined in light of the now well-determined excited-state electronic structure. The results serve to underscore the importance of complete characterization of the electronic structures of transition metal complexes before embarking on ultrafast studies of their excited-state properties.

  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.

  8. Electrochemical impedance spectroscopy study of carbon electrodes prepared from date pits and fibers of oil palm empty fruit bunches

    NASA Astrophysics Data System (ADS)

    Hamdan, E.; Deraman, M.; Suleman, M.; Nor, N. S. M.; Basri, N. H.; Hanappi, M. F. Y. M.; Sazali, N. E. S.; Tajuddin, N. S. M.; Omar, R.; Othman, M. A. R.; Shamsudin, S. A.

    2016-11-01

    In this study, we produced pre-carbonized date pits (PDP) and self-adhesive carbon grains (SACGs) from oil palm empty fruit bunches (EFB) by a low temperature (200°C for DP and 280°C for SACGs, respectively) carbonization method followed by KOH treatment to obtain KOH treated PDP (T-PDP) and KOH treated SACGs (T-SACGs). Four sets of green monolith (GMs) denoted as GM-A, GM-B, GM-C and GM-D were prepared respectively from SACGs (100 wt. %), mixture of PDP and SACGs (50:50 wt. %), T-SACGs (100 wt. %), and mixture of T-SACGs and T-PDP (50:50 wt. %), respectively. From these GMs the respective activated carbon monolith (ACMs) electrodes namely ACM-A, ACM-B, ACM-C and ACM-D were prepared via carbonization (N2 carbonization) and activation (CO2 environment). These ACMs electrodes were used to fabricate the corresponding EDLC cells: Cell-A, Cell-B, Cell-C and Cell-D, respectively. The electrochemical impedance spectroscopy tests conducted on the cells found that the Cell-D showed the maximum value of specific capacitance, Csp (˜ 135 F g-1) whereas the Cell-A showed the minimum values of ESR and characteristic response time, respectively, ˜ 2.14 Ω and ˜ 46 s. Therefore, it can be concluded that the KOH treatment can improve the capacitance but caused the increase in the ESR and response time.

  9. High-pressure Raman spectroscopic study of magnetite Fe3O4

    NASA Astrophysics Data System (ADS)

    Kyono, A.; Ahart, M.; Yamanaka, T.; Mysen, B.; Mao, H.; Hemley, R. J.

    2010-12-01

    We report in situ Raman spectroscopic studies of magnetite in a diamond-anvil cell under hydrostatic conditions up to 60 GPa at room temperature. Magnetite with ideal chemical formula Fe3O4 crystallizes in the face-centered cubic spinel-type structure. There are five first-order Raman active modes (A1g + Eg + 3F2g) in the Fd3m space group of the spinel structure. Three modes at nearby 300, 600 and 700 cm-1 are observed under pressure conditions. In the cubic spinels including ferrites, the highest frequency at about 700 cm-1 corresponds to the stretching vibrations of oxygen atoms in the tetrahedral coordination and can be assigned to the A1g symmetry. The other strong peak centered at about 600 and 300 cm-1 can be assigned to the F2g and Eg symmetries. The remaining two modes could not be observed unambiguously in the measurements. The peak positions and shapes of the Raman spectra agree well with previously published data measured under ambient condition. With increasing pressure, the frequencies of the two modes A1g , F2g and Eg increase continuously up to about 30 GPa with pressure derivatives of 2.7, 4.5 and 1.4 cm-1/GPa, respectively. There is no obvious degradation of crystal symmetry or structural change within this pressure range. Upon elevation of pressure to nearby 30 GPa, the F2g mode starts to display a variation in the spectra and its intensity gradually decreases due to the tetragonal-orthorhombic phase transition. The splitted mode into B1g, B2g, B3g from F2g completely disappears at a pressure of 40 GPa. The most striking characteristic of Raman spectroscopy of magnetite is that the pressure-induced suppression leads to a significant extinction of the Raman active mode derived from F2g symmetry. Only one peak resulting from A1g mode can be observed continuously up to 60 GPa. Consequently, the results of the Raman spectroscopic study about phase transformation are in good agreement with that of the X-ray diffraction study.

  10. Raman spectroscopic study of the frustrated spin 1/2 antiferromagnet clinoatacamite

    NASA Astrophysics Data System (ADS)

    Liu, Xiao-Dong; Zheng, Xu-Guang; Meng, Dong-Dong; Xu, Xing-Liang; Guo, Qi-Xin

    2013-06-01

    Raman spectroscopy is a valuable and complementary tool for studying geometrically frustrated magnetic systems due to the intrinsic spin-phonon coupling. Here, we report on a Raman spectroscopic study of the geometrically frustrated spin 1/2 antiferromagnet microcrystalline clinoatacamite Cu2(OH)3Cl, focusing on the anomalous transition into the intermediate phase at Tc1 = 18.1 K. By measuring the temperature-dependent (295-4 K) full spectral profiles and main representative modes in spectral regions from 4000 to 95 cm-1, we observed probable signatures of successive magnetic transitions near Tc1 = 18 K and Tc2 = 6.4 K in the Raman band frequencies and peak widths of the representative modes. Further, we observed a pronounced Raman spectroscopy background featuring a broad continuum at all temperatures. A quantitative analysis reveals that spin fluctuations may exist on a picosecond time scale in the intermediate phase. The short time scale falls out of the μSR time window; therefore, in the intermediate phase, the μSR study as reported in (2005 Phys. Rev. Lett. 95 057201) apparently only probed the local field of the ordered spins but overlooked the quickly fluctuating ones. This is likely to give a reasonable explanation of the fact that only a small entropy release occurs at Tc1 = 18 K although a long-range order is formed.

  11. Spectroscopic and molecular modeling studies on the interactions of N-Methylformamide with superoxide dismutase.

    PubMed

    Kalyani, Durai; Jyothi, Kanagaraj; Sivaprakasam, Chinnarasu; Nachiappan, Vasanthi

    2014-04-24

    N-Methylformamide, a polar solvent has a wide industrial applications and it is well-known for hepatotoxicity. The interaction between NMF with superoxide dismutase, an antioxidant defense enzyme has been studied for the first time using spectroscopic methods including Fourier transform infrared (FT-IR) spectroscopy, Circular dichroism (CD) spectroscopy and UV-visible spectroscopy under simulative physiological conditions and also by molecular modelling. Fourier Transform Infra Red analysis showed that the change in peak positions and shapes revealed that the secondary structure of SOD had been changed by the interaction with NMF. The data of CD spectra also confirmed that NMF decreased the degree of secondary structure of SOD, which directly resulted in destabilization of enzyme. We studied the inhibitory effect of NMF on enzyme kinetics by pyrogallol autoxidation revealed that protein-ligand complex caused structural unfolding which resulted in enzymatic inhibition. Thus the spectral behaviour of superoxide dismutase provides data concerning its conformational changes in the presence of NMF. Furthermore, molecular docking was applied to explore the binding mode between the protein-ligand complex. This suggested that Asn54 and Val302 residues of dimeric protein were predicted to interact with NMF. The present study provides direct evidence at a molecular level to show that exposure to NMF cause perturbation in its structure and function.

  12. Spectroscopic and structural studies of allyl urethane derivative of Monensin A sodium salt

    NASA Astrophysics Data System (ADS)

    Huczyński, Adam; Janczak, Jan; Brzezinski, Bogumil; Bartl, Franz

    2013-07-01

    A new derivative of polyether antibiotic Monensin A sodium salt its allyl urethane (MON-UR2-Na) was synthesised and its structure was studied by X-ray, FT-IR, NMR, and ESI-MS methods. The results of these studies demonstrated that the oxygen atom of the Cdbnd O urethane group is not engaged in the coordination of the Na+ as postulated previously. The crystal space group is P21 with a = 12.0378(11), b = 12.4495(11), c = 14.9690(14), β = 94.791(8) and Z = 2. The structure determined in the present study exhibits significant differences with respect to the earlier published structure of phenyl urethane of Monensin. A comparison of these structures clearly shows that not only the functional urethane group but also its substituent strongly influence the structure of this type of derivatives of Monensin A. X-ray data and spectroscopic and spectrometric behaviour of the new derivative of Monensin A are discussed in detail and compared to the structure of phenyl urethane of Monensin A sodium salt.

  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. Binding characteristics of psoralen with trypsin: Insights from spectroscopic and molecular modeling studies.

    PubMed

    Liu, Yingying; Zhang, Guowen; Liao, Yijing; Wang, Yaping

    2015-01-01

    Psoralen (PSO) is a naturally occurring furanocoumarin with a variety of pharmacological activities, however very limited information on the interaction of PSO with trypsin is available. In this study, the binding characteristics between PSO and trypsin at physiological pH were investigated using a combination of fluorescence, UV-vis absorption, circular dichroism (CD), Fourier transform infrared (FT-IR) spectroscopic, chemometric and molecular modeling approaches. It was found that the fluorescence quenching of trypsin by PSO was a static quenching procedure, ascribing the formation of a PSO-trypsin complex. The binding of PSO to trypsin was driven mainly by hydrophobic forces as the positive enthalpy change and entropy change values. The molecular docking showed that PSO inserted into the active site pocket of trypsin to interact with the catalytic residues His57, Asp102 and Ser195 and may cause a decrease in trypsin activity. The results of CD and FT-IR spectra along with the temperature-induced denaturation studies indicated that the addition of PSO to trypsin led to the changes in the secondary structure of the enzyme. The concentration profiles and spectra of the three components (PSO, trypsin, and PSO-trypsin complex) obtained by multivariate curve resolution-alternating least squares analysis exhibited the kinetic processes of PSO-trypsin interaction. This study will be helpful to understand the mechanism of PSO that affects the conformation and activity of trypsin in biological processes.

  15. 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.

  16. 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.

  17. Spectroscopic studies on the conformational transitions of a bovine growth hormone releasing factor analog

    NASA Astrophysics Data System (ADS)

    Sarver, Ronald W.; Friedman, Alan R.; Thamann, Thomas J.

    1997-10-01

    The secondary structure of the bovine growth hormone releasing factor analog, [Ile 2, Ser 8,28, Ala 15, Leu 27, Hse 30] bGRF(1-30)-NH-Ethyl, acetate salt (U-90699F) was studied in solution by Fourier transform infrared and Raman spectroscopies. Spectroscopic studies revealed that concentrated aqueous solutions of U-90699F (100 mg ml -1) undergo a secondary structure transition from disordered coil/α-helix to intermolecular β-sheet. Disordered coil and α-helical structure were grouped together in the infrared and Raman studies since the amide I vibrations are close in frequency and overlap in assignments was possible. Before the conformational transition, the facile exchange of the peptide's amide hydrogens for deuterium indicated that the majority of amide hydrogens were readily accessible to solvent. The kinetics of the conformational transition coincided with an increase in solution viscosity and turbidity. An initiation phase preceded the conformational transition during which only minor spectral changes were observed by infrared spectroscopy. The initiation phase and reaction kinetics were consistent with a highly cooperative nucleation ultimately leading to a network of intermolecular β-sheet structure and gel formation. Increased temperature accelerated the conformational transition. The conformational transition was thermally irreversible but the β-sheet structure of aggregated or gelled peptide could be disrupted by dilution and agitation.

  18. 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.

  19. 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.

  20. Spectroscopic study of humic acids fractionated by means of tangential ultrafiltration

    NASA Astrophysics Data System (ADS)

    Francioso, O.; Sánchez-Cortés, S.; Casarini, D.; Garcia-Ramos, J. V.; Ciavatta, C.; Gessa, C.

    2002-05-01

    Different chemical and spectroscopic techniques—diffuse reflectance infrared Fourier transform (DRIFT), surface-enhanced Raman spectroscopy (SERS), and 1H, 13C nuclear magnetic resonance (NMR) have been applied to investigate a peat humic acid (HA) separated by tangential ultrafiltration into different nominal molecular weight (NMW) fractions. Each fraction analyzed showed a characteristic DRIFT and NMR pattern. High nominal molecular weight fractions were mainly characterized by long chains of methyl and methylene groups and poorly substituted aromatic rings, while in low nominal molecular weight fractions (L-NMW), phenolic and oxygen-containing groups were predominant. A comparative study on fractions before and after treatment with 0.5 M HCl was carried out. Purified fractions showed either an increase in the carboxylate and phenolic OH groups or an improvement in signal-to-noise ratio of their NMR spectra. The SERS study of NMW fractions allowed significative information on structure and conformation of these fractions. In particular, L-NMW fractions showed a great structural modification, when different alkaline extractants or treatment with HCl were used. Humic-like substances obtained by catechol and gallic acid polymerization on metal surface were investigated using SERS. The SERS spectra of these polymers were compared and discussed with those of NMW HA fractions.

  1. Mechanism and conformational studies of farrerol binding to bovine serum albumin by spectroscopic methods

    NASA Astrophysics Data System (ADS)

    Zhang, Guowen; Wang, Lin; Fu, Peng; Hu, Mingming

    2011-11-01

    The mechanism and conformational changes of farrerol binding to bovine serum albumin (BSA) were studied by spectroscopic methods including fluorescence quenching technique, UV-vis absorption, circular dichroism (CD) spectroscopy and Fourier transform infrared (FT-IR) spectroscopy under simulative physiological conditions. The results of fluorescence titration revealed that farrerol could strongly quench the intrinsic fluorescence of BSA through a static quenching procedure. The thermodynamic parameters enthalpy change and entropy change for the binding were calculated to be -29.92 kJ mol -1 and 5.06 J mol -1 K -1 according to the van't Hoff equation, which suggested that the both hydrophobic interactions and hydrogen bonds play major role in the binding of farrerol to BSA. The binding distance r deduced from the efficiency of energy transfer was 3.11 nm for farrerol-BSA system. The displacement experiments of site markers and the results of fluorescence anisotropy showed that warfarin and farrerol shared a common binding site I corresponding to the subdomain IIA of BSA. Furthermore, the studies of synchronous fluorescence, CD and FT-IR spectroscopy showed that the binding of farrerol to BSA induced conformational changes in BSA.

  2. Synthesis, structural and spectroscopic studies of 2-oxoacenaphthylen-1(2H)-ylidene nicotinohydrazide

    NASA Astrophysics Data System (ADS)

    Henriques, M. S. C.; Del Amparo, R.; Pérez-Álvarez, D.; Nogueira, B. A.; Rodríguez-Argüelles, M. C.; Paixão, J. A.

    2017-02-01

    The synthesis of a new hydrazone, 2-oxoacenaphthylen-1(2H)-ylidene nicotinohydrazide, and its structural and spectroscopic characterization is reported. The obtained powder was recrystallized from DMSO and ethanol that afforded small crystals used for single-crystal X-ray diffraction studies. The compound was found to crystallize in two polymorphs, depending on the crystallization conditions. One of the polymorphs (form I) crystallizes in the centrosymmetric P21/c monoclinic space group, the other (form II) crystallizes in the non-centrosymmetric, but achiral, orthorhombic space group P212121. Conformation of the molecules is similar in both polymorphs, but the network of weak intermolecular interactions determining the crystal packing is different. In form II an additional C-H⋯O bond connects molecules related by the screw-axis running parallel to the a-axis. Crystals of both polymorphs were also screened by FT-IR and Raman microscopy; a detailed analysis of the spectra and comparison with those of the isolated molecule calculated by ab-initio HF/MP2 and DFT/B3LYP methods using a correlation consistent cc-pVDZ basis set is presented. In addition, UV-vis and NMR studies were performed in solution.

  3. Hydrogen bonding interactions in nicotinamide Ionic Liquids: A comparative spectroscopic and DFT studies

    NASA Astrophysics Data System (ADS)

    Shukla, Madhulata

    2017-03-01

    Being biodegradable in nature nicotinamide based Ionic Liquids (ILs) are gaining much attention now a day. Nicotinamide iodide (i.e 1-methyl-3ethoxy carbonyl pyridinium iodide (mNicI)) and 1-methyl-3ethoxy carbonyl pyridinium trifilimide (mNicNTf2) new ILs has been synthesized and has been characterized using different spectroscopic techniques like NMR, UV visible and infrared spectroscopy. Theoretical studies have been performed on several nicotinamide ILs. Geometry and spectral features were further characterized by Density Functional Theory (DFT) calculation. NBO charge distribution and electrostatic potential diagram presents in depth knowledge about interactions between cation and anion. A comparative theoretical study between mNicI and its other analogues i. e 1-methyl-3 ethoxy carbonyl pyridinium chloride and bromide i. e mNicCl and mNicBr has also been performed. Csbnd H⋯X hydrogen bonding along with C⋯X interaction has been reported for the first time for the nicotinamide based ILs. C2sbnd H stretching frequency shifts to higher wavenumber with change to a lesser electronegative anion. mNicCl and mNicBr are expected to be solid in nature with the evidence from the red shift in stretching frequency as compared to mNicI. TD-DFT calculation of mNicI proved that pale yellow color of liquid is due to inherent transition from anion to cation.

  4. The systems V(IV)O(2+)-glutathione and related ligands: a potentiometric and spectroscopic study.

    PubMed

    Pessoa, João Costa; Tomaz, Isabel; Kiss, Tamás; Kiss, Erzsébet; Buglyó, Péter

    2002-03-01

    The equilibria in the system V(IV)O(2+)-glutathione in aqueous solution were studied in the pH range 2-11 by a combination of pH-potentiometry and spectroscopy (EPR, visible absorption and circular dichroism). The results of the various methods are consistent and the equilibrium model includes the species MLH(3), MLH(2), MLH, ML(2)H(2), MLH(-1), and MLH(-2) and several hydrolysis products (where H(4)L denotes totally protonated glutathione); individual formation constants and spectra are given. ML(2)H(2) is the predominant species at physiological pH. Plausible structures for each stoichiometry are discussed. The related V(IV)O(2+) systems of S-methylglutathione and gamma- L-glutamyl- L-cysteinyl ethyl ester were studied by means of the same spectroscopic techniques in order to support the established binding modes for the glutathione complexes. The importance of glutathione and oxidized glutathione in binding V(IV)O(2+) in cells is assessed.

  5. Spectroscopic study on binding of gentisic acid to bovine serum albumin.

    PubMed

    Garzón, Andrés; Bravo, Iván; Carrión-Jiménez, M Rosario; Rubio-Moraga, Ángela; Albaladejo, José

    2015-01-01

    The interaction of (gentisic acid) GA with (bovine serum albumin) BSA has been studied by different spectroscopic techniques. GA is a monoanionic specie at the working pH of 7.4, it was determined by combining UV-Vis absorption spectroscopy and theoretical calculations. A set of fluorescence quenching experiments at different temperatures was carried out employing the native fluorescence of BSA. A Stern-Volmer constant (KSV) of (2.07±0.12)×10(4) mol(-1) L and a binding constant (Ka) of (8.47±4.39)×10(3) were determined at 310 K. The static quenching caused by the BSA-GA complex formation seems to play a significant role in the overall quenching process. A single binding site on BSA for GA was observed. ΔH=-55.6±0.2 kJ mol(-1) and ΔS=-104.3±0.6 J mol(-1) K(-1) were determined in a set of experiments on the dependence of Ka with the temperature. The binding process is, therefore, spontaneous and enthalpy-driven. Van der Waals forces and hydrogen bonds could also play the major role in the binding mode. The secondary structure changes of BSA in the absence and presence of GA were studied by FTIR and UV-Vis absorption spectroscopy.

  6. Study on the interaction characteristics of cefamandole with bovine serum albumin by spectroscopic technique.

    PubMed

    Wang, Qian; Liu, Xuyang; Su, Ming; Shi, Zhihong; Sun, Hanwen

    2015-02-05

    The interaction of cefamandole with bovine serum albumin (BSA) was studied by fluorescence quenching in combination with UV-Vis spectroscopic method under near physiological conditions. The fluorescence quenching rate constants and binding constants for BSA-cefamandole system were determined at different temperatures. The fluorescence quenching of BSA by cefamandole is due to static quenching and energy transfer. The results of thermodynamic parameters, ΔH (-268.0 kJ mol(-1)), ΔS (-810.0 J mol(-1) K(-1)) and ΔG (-26.62 to -8.52 kJ mol(-1)), indicated that van der Waals interaction and hydrogen bonding played a major role for cefamandole-BSA association. The competitive experiments demonstrated that the primary binding site of cefamandole on BSA was located at site III in sub-domain IIIA of BSA. The distance between cefamandole and a tryptophane unit was estimated to be 1.18 nm based on the Förster resonance energy transfer theory. The binding constant (KA) of BSA-cefamandole at 298 K was 2.239×10(4) L mol(-1). Circular dichroism spectra, synchronous fluorescence and three-dimensional fluorescence studies showed that the presence of cefamandole could change the conformation of BSA during the binding process.

  7. 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.

  8. 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.

  9. The Rio Tinto Mars analogue site: an extremophilic Raman spectroscopic study.

    PubMed

    Edwards, Howell G M; Vandenabeele, Peter; Jorge-Villar, Susana E; Carter, Elizabeth A; Perez, Fernando Rull; Hargreaves, Michael D

    2007-12-15

    The Rio Tinto site is recognised as a terrestrial Mars analogue because of the presence of jarosite and related sulfates which have recently been identified by the NASA Mars Exploration Rover "Opportunity" in the El Capitan region of Meridiani Planum on Mars. It has long been known that acidophilic microbial action is responsible for the deep blood-red colour of the water in Rio Tinto, where the pH varies from about 1.5 to 3.0 and the water is rich in iron and sulfur. Following recent Raman spectroscopic characterisation of the mineral phases of the Rio Tinto system, we report here a study of the biological components found in several specimens of deposited minerals and near the waterside that were collected during a GeoRaman VI Conference organized field trip in 2006. Key biosignatures were found for carotenoids, scytonemin and mycosporine-like amino acids, which are indicative of the biological colonisation of exposed mineral substrates; information from this study will be useful for targeting Martian sites using a miniaturized Raman instrument where the biosignatures of relict or extant life could remain in the geological record.

  10. Interaction of imatinib mesylate with human serum transferrin: The comparative spectroscopic studies.

    PubMed

    Śliwińska-Hill, Urszula

    2017-02-15

    Imatinib mesylate (Imt) is a tyrosine kinase inhibitor mainly used in the treatment of Philadelphia chromosome-positive chronic myelogenous leukemia (Ph+CML). Human serum transferrin is the most abundant serum protein responsible for the transport of iron ions and many endogenous and exogenous ligands. In this study the mechanism of interactions between the imatinib mesylate and all states of transferrin (apo-Tf, Htf and holo-Tf) has been investigated by fluorescence, ultraviolet-visible (UV-vis), circular dichroism (CD) and zeta potential spectroscopic methods. Based on the experimental results it was proved that under physiological conditions the imatinib mesylate binds to the each form of transferrin with a binding constant c.a. 10(5)M(-1). The thermodynamic parameters indicate that hydrogen bonds and van der Waals were involved in the interaction of apo-Tf with the drug and hydrophobic and ionic strength participate in the reaction of Htf and holo-Tf with imatinib mesylate. Moreover, it was shown that common metal ions, Zn(2+) and Ca(2+) strongly influenced apo-Tf-Imt binding constant. The CD studies showed that there are no conformational changes in the secondary structure of the proteins. No significant changes in secondary structure of the proteins upon binding with the drug and instability of apo-Tf-Imt system are the desirable effects from pharmacological point of view.

  11. Spectroscopic study of the authentic emitter of AMPPD chemiluminescence in alkaline aqueous solution.

    PubMed

    Tu, Langping; Wang, Yu; Yang, Yifei; Bakker, Bert H; Kong, Xianggui; Brouwer, Albert M; Buma, Wybren J; Zhang, Hong

    2010-07-07

    To design more effective CIEEL (chemically initiated electron exchange luminescence) systems demands a complete picture of the dynamics of the chemiluminescence, which is often a challenge. In this work, photoluminescence of the methyl m-oxybenzoate anion - the authentic emitter of AMPPD (3-[2-spiroadamantane]-4-methoxy-4-[3-phosphoryloxy]-phenyl-1,2-dioxetane) in aqueous solvent has been studied. Combining the effect of solvent properties, e.g. pH value, and spectroscopic studies employing steady-state and ultrafast time-resolved emission and absorption and (1)H NMR techniques, a novel mechanism is proposed. We conclude that the deviation of emission peaks between chemiluminescence and photoluminescence of the authentic emitter of AMPPD i.e. the methyl m-oxybenzoate anion, in alkaline aqueous solvents is due to its hydrolysis, rather than the hydrogen-bonding effect as has been assumed so far. Besides, the hydrogen-bonding is suggested to play a key role in significantly decreasing the chemiluminescence yield of AMPPD in aqueous solution by shortening the lifetime of the excited authentic emitter to 10 ps order of magnitude - three orders of magnitude shorter than the previously reported value ( approximately 10 ns). These results shed light on the chemiluminescence dynamics of AMPPD and facilitate the design of more effective CIEEL systems.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Synthesis, structural and spectroscopic studies of 2-oxoacenaphthylen-1(2H)-ylidene nicotinohydrazide.

    PubMed

    Henriques, M S C; Del Amparo, R; Pérez-Álvarez, D; Nogueira, B A; Rodríguez-Argüelles, M C; Paixão, J A

    2017-02-05

    The synthesis of a new hydrazone, 2-oxoacenaphthylen-1(2H)-ylidene nicotinohydrazide, and its structural and spectroscopic characterization is reported. The obtained powder was recrystallized from DMSO and ethanol that afforded small crystals used for single-crystal X-ray diffraction studies. The compound was found to crystallize in two polymorphs, depending on the crystallization conditions. One of the polymorphs (form I) crystallizes in the centrosymmetric P21/c monoclinic space group, the other (form II) crystallizes in the non-centrosymmetric, but achiral, orthorhombic space group P212121. Conformation of the molecules is similar in both polymorphs, but the network of weak intermolecular interactions determining the crystal packing is different. In form II an additional C-H⋯O bond connects molecules related by the screw-axis running parallel to the a-axis. Crystals of both polymorphs were also screened by FT-IR and Raman microscopy; a detailed analysis of the spectra and comparison with those of the isolated molecule calculated by ab-initio HF/MP2 and DFT/B3LYP methods using a correlation consistent cc-pVDZ basis set is presented. In addition, UV-vis and NMR studies were performed in solution.

  17. DNA-binding study of anticancer drug cytarabine by spectroscopic and molecular docking techniques.

    PubMed

    Shahabadi, Nahid; Falsafi, Monireh; Maghsudi, Maryam

    2017-01-02

    The interaction of anticancer drug cytarabine with calf thymus DNA (CT-DNA) was investigated in vitro under simulated physiological conditions by multispectroscopic techniques and molecular modeling study. The fluorescence spectroscopy and UV absorption spectroscopy indicated drug interacted with CT-DNA in a groove-binding mode, while the binding constant of UV-vis and the number of binding sites were 4.0 ± 0.2 × 10(4) L mol(-1) and 1.39, respectively. The fluorimetric studies showed that the reaction between the drugs with CT-DNA is exothermic. Circular dichroism spectroscopy was employed to measure the conformational change of DNA in the presence of cytarabine. Furthermore, the drug induces detectable changes in its viscosity for DNA interaction. The molecular modeling results illustrated that cytarabine strongly binds to groove of DNA by relative binding energy of docked structure -20.61 KJ mol(-1). This combination of multiple spectroscopic techniques and molecular modeling methods can be widely used in the investigation on the interaction of small molecular pollutants and drugs with biomacromolecules for clarifying the molecular mechanism of toxicity or side effect in vivo.

  18. Interaction of imatinib mesylate with human serum transferrin: The comparative spectroscopic studies

    NASA Astrophysics Data System (ADS)

    Śliwińska-Hill, Urszula

    2017-02-01

    Imatinib mesylate (Imt) is a tyrosine kinase inhibitor mainly used in the treatment of Philadelphia chromosome-positive chronic myelogenous leukemia (Ph + CML). Human serum transferrin is the most abundant serum protein responsible for the transport of iron ions and many endogenous and exogenous ligands. In this study the mechanism of interactions between the imatinib mesylate and all states of transferrin (apo-Tf, Htf and holo-Tf) has been investigated by fluorescence, ultraviolet-visible (UV-vis), circular dichroism (CD) and zeta potential spectroscopic methods. Based on the experimental results it was proved that under physiological conditions the imatinib mesylate binds to the each form of transferrin with a binding constant c.a. 105 M- 1. The thermodynamic parameters indicate that hydrogen bonds and van der Waals were involved in the interaction of apo-Tf with the drug and hydrophobic and ionic strength participate in the reaction of Htf and holo-Tf with imatinib mesylate. Moreover, it was shown that common metal ions, Zn2 + and Ca2 + strongly influenced apo-Tf-Imt binding constant. The CD studies showed that there are no conformational changes in the secondary structure of the proteins. No significant changes in secondary structure of the proteins upon binding with the drug and instability of apo-Tf-Imt system are the desirable effects from pharmacological point of view.

  19. Spectroscopic Study of ThCl+ by Two-Photon Ionization

    NASA Astrophysics Data System (ADS)

    Bartlett, Joshua; VanGundy, Robert A.; Heaven, Michael; Peterson, Kirk

    2016-06-01

    Despite the irreplaceable role experimental data plays for evaluating the performance of computational predictions, diatomic actinide species have not received much spectroscopic attention. As an early actinide element, thorium-containing species are ideal candidates for these types of studies. The electronic structure is expected to be relatively simple compared to later actinides, and therefore allows straightforward assessment of calculations. Here, we have studied ThCl+ for the first time via resonant two-photon ionization of jet-cooled ThCl produced by laser ablation of the metal reacted with dilute Cl2. Laser-induced Fluorescence (LIF) spectra have been recorded for the neutral molecule from 16000 - 23500 cm-1 in search of a suitable intermediate state for subsequent two-photon ionization experiments. Monochromator dispersion of the fluorescence has recovered the ground state vibration and anharmonic constants of ThCl. Resonant Two-Photon Ionization (R2PI) within a time-of-flight mass spectrometer was used to confirm ThCl production, and Pulsed Field Ionization Zero Kinetic Energy photoelectron spectroscopy (PFI-ZEKE) has been performed to identify the ionization energy as well as several of the low-lying states of the ThCl+ molecule. These constants have been predicted at the CASPT2 and CCSD(T) levels of theory, and a discussion of the calculations' performance will be presented alongside the recorded spectra.

  20. 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.

  1. Theoretical and spectroscopic studies of pyridyl substituted bis-coumarins and their new neodymium (III) complexes

    NASA Astrophysics Data System (ADS)

    Kostova, Irena; Trendafilova, Natasha; Mihaylov, Tzvetan

    2005-07-01

    Ab initio, DFT and spectroscopic studies of 3,3'-( o-pyridinomethylene)di-[4-hydroxycoumarin], 3,3'-( m-pyridinomethylene)di-[4-hydroxycoumarin] and 3,3'-( p-pyridinomethylene)di-[4-hydroxycoumarin] were performed. The molecular and electronic structures of the compounds were investigated using accurate HF and B3LYP/6-31G(d) calculations. Molecular quantities as vertical ionization potential, electron affinity, electronegativity, hardness and electrophilicity indices of the neutral species were calculated and discussed. Molecular electrostatic potential was considered as an additional molecular characteristic for predicting the most probable sites for electrophilic attack. The molecular structure and quantities of the dianionic species, which are active in solution, were calculated and discussed. The theoretical results suggested that both carbonyl and both hydroxyl oxygen atoms are preferred binding sites for electrophilic attack, in particular for a metal coordination. Further, the coordination abilities of the compounds were studied in complexation reactions with Nd(III). Complexes of Nd(III) with o-, m- and p-3,3'-(pyridinomethylene)di-[4-hydroxycoumarin] were synthesized and characterized by different physicochemical methods: elemental analysis, IR, 1H NMR spectroscopies and mass spectral data. The experimental data confirmed the theoretical predictions that the ligands in Nd(III) complexes are tetradentate and bound the metal ion through both carbonyl and both deprotonated hydroxyl oxygen atoms.

  2. Optical and spectroscopic studies on tannery wastes as a possible source of organic semiconductors

    NASA Astrophysics Data System (ADS)

    Nashy, El-Shahat H. A.; Al-Ashkar, Emad; Abdel Moez, A.

    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.

  3. 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

  4. 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

  5. Spectroscopic studies on the interaction of bovine serum albumin with surfactants and apigenin

    NASA Astrophysics Data System (ADS)

    Zhao, Xu-Na; Liu, Yi; Niu, Li-Yuan; Zhao, Chen-Ping

    The binding of apigenin (Ap) to bovine serum albumin (BSA) has been studied using the methods of fluorescence spectroscopy and UV-vis absorption spectroscopy. The spectroscopic analysis of the quenching mechanism indicates that the quenching constants are inversely correlated with the temperatures and the quenching process could result from a static interaction. The type of interaction force was discussed and the binding site of Ap was in site I (subdomain IIA) of BSA. The thermodynamic parameters ΔH and ΔS are -42.02 kJ mol-1 and -48.31 J mol-1 K-1, respectively and the negative ΔG implying that the binding interaction was spontaneous. The distance r between BSA and Ap was calculated according to Förster's theory and the value is 3.44 nm. The synchronous and three-dimensional fluorescence spectra show that the binding of Ap to BSA could lead to the changes in the conformation and microenvironment of BSA. At the same time, the effects of ionic surfactants on the interaction of Ap and BSA have also been investigated.

  6. 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.

  7. Spectroscopic studies on the oxidation of carbonyl compounds by OH radicals in the aqueous solution

    NASA Astrophysics Data System (ADS)

    Schaefer, T.; Herrmann, H.

    2009-04-01

    The atmospheric conversation and degradation of volatile organic compounds (VOCs) is often initiated by radical reactions. One of the most important radical in the atmosphere is the OH-radical. Oxidation reactions of water soluble organic compounds in the atmospheric aqueous phase (cloud droplets, fog, rain, deliquescent particles) can be as fast as in the gas phase, but lead to different reaction products or different product distributions. The objective of this work is to identify and characterize the various transient species formed in the oxidation of carbonyl compounds such as acetone. This characterization is necessary to measure rate constants of elementary reaction steps in the course of the degradation process. The spectroscopic and kinetic information obtained will allow a better understanding of the atmospheric fate of carbonyl compounds. In order to characterize the optical properties of the formed transient compounds (e.g. organic peroxy radicals) a laser photolysis long path absorption apparatus coupled with a CCD-camera / grating combination is used. With this technique time resolved spectra (at different delay times after the excimer laser pulse) of the reactants and products can be recorded. Within this contribution organic peroxy radical spectra of the following parent carbonyl compounds (a) acetone, (b) hydroxyacetone, (c) methylglyoxal and (d) pyruvic acid will be presented, discussed and compared with literature data. OH radicals were generated directly in the reaction cell by the photolysis of hydrogen peroxide (H2O2) at 248 nm. All reactions were studied at T = 298K in the aqueous solution.

  8. 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.

  9. 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.

  10. 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.

  11. Newly synthesized dihydroquinazoline derivative from the aspect of combined spectroscopic and computational study

    NASA Astrophysics Data System (ADS)

    El-Azab, Adel S.; Mary, Y. Sheena; Mary, Y. Shyma; Panicker, C. Yohannan; Abdel-Aziz, Alaa A.-M.; El-Sherbeny, Magda A.; Armaković, Stevan; Armaković, Sanja J.; Van Alsenoy, Christian

    2017-04-01

    In this work, spectroscopic characterization of 2-(2-(4-oxo-3-phenethyl-3,4-dihydroquinazolin-2-ylthio)ethyl)isoindoline-1,3-dione have been obtained with experimentally and theoretically. Complete assignments of fundamental vibrations were performed on the basis of the potential energy distribution of the vibrational modes and good agreement between the experimental and scaled wavenumbers has been achieved. Frontier molecular orbitals have been used as indicators of stability and reactivity. Intramolecular interactions have been investigated by NBO analysis. The dipole moment, linear polarizability and first and second order hyperpolarizability values were also computed. In order to determine molecule sites prone to electrophilic attacks DFT calculations of average local ionization energy (ALIE) and Fukui functions have been performed as well. Intra-molecular non-covalent interactions have been determined and analyzed by the analysis of charge density. Stability of title molecule have also been investigated from the aspect of autoxidation, by calculations of bond dissociation energies (BDE), and hydrolysis, by calculations of radial distribution functions after molecular dynamics (MD) simulations. In order to assess the biological potential of the title compound a molecular docking study towards breast cancer type 2 complex has been performed.

  12. Mediaeval cantorals in the Valladolid Biblioteca: FT-Raman spectroscopic study.

    PubMed

    Edwards, H G; Farwell, D W; Rull Perez, F; Medina Garcia, J

    2001-03-01

    Raman spectroscopic studies of three mediaeval cantorals in the Biblioteca of the University of Valladolid has revealed information about the pigments used on these large manuscripts. Although executed in a simple colour palette, very pure cinnabar was used as the major colourant, offsetting the carbon black of the verses and script. A dark blue colour was achieved using a mixture of azurite (basic copper carbonate) and carbon, whereas a light blue colour was azurite alone. A grey colour was achieved using azurite, carbon particles and a calcareous 'limewash'. A yellow pigment, used sparely in the cantorals was ascribed to saffron; unusually, there was no evidence for the presence of the yellow mineral pigments orpiment, realgar and massicot. In several regions of the vellum specimens, evidence for biodeterioration was observed through the signatures of hydrated calcium oxalate. We report for the first time the Raman spectra of pigment in situ on a vellum fragment, which also shows evidence of substrate bands; comparison of black and red pigmented regions of vellum specimens has shown the presence of calcium oxalate in the black pigmented script but not in the red pigment regions, which suggests that the cinnabar in the red-pigmented regions acts as a toxic protectant for the vellum substrate against biological colonisation processes.

  13. 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.

  14. Dissolution of tablet-in-tablet formulations studied with ATR-FTIR spectroscopic imaging.

    PubMed

    Wray, Patrick S; Clarke, Graham S; Kazarian, Sergei G

    2013-03-12

    This work uses ATR-FTIR spectroscopic imaging to study the dissolution of delayed release and pH resistant compressed coating pharmaceutical tablets. Tablets with an inner core and outer shell were constructed using a custom designed compaction cell. The core of the delayed release tablets consisted of hydroxypropyl methylcellulose (HPMC) and caffeine. The shell consisted of microcrystalline cellulose (MCC) and glucose. The core of the pH resistant formulations was an ibuprofen and PEG melt and the shell was constructed from HPMC and a basic buffer. UV/vis spectroscopy was used to monitor the lag-time of drug release and visible optical video imaging was used as a complementary imaging technique with a larger field of view. Two delayed release mechanisms were established. For tablets with soluble shell sections, lag-time was dependent upon rapid shell dissolution. For tablets with less soluble shells, the lag-time was controlled by the rate of dissolution medium ingress through the shell and the subsequent expansion of the wet HPMC core. The pH resistant formulations prevented crystallization of the ibuprofen in the core during dissolution despite an acidic dissolution medium. FTIR imaging produced important information about the physical and chemical processes occurring at the interface between tablet sections during dissolution.

  15. 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.

  16. Structural, spectroscopic and DFT study of 4-methoxybenzohydrazide Schiff bases. A new series of polyfunctional ligands.

    PubMed

    Ferraresi-Curotto, Verónica; Echeverría, Gustavo A; Piro, Oscar E; Pis-Diez, Reinaldo; González-Baró, Ana C

    2015-02-25

    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 O-H⋯N interactions in salicylaldehyde derivatives between the O-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.

  17. 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.

  18. Enzyme inhibition, radical scavenging, and spectroscopic studies of vanadium(IV)-hydrazide complexes.

    PubMed

    Ashiq, Uzma; Jamal, Rifat Ara; Mahroof-Tahir, Mohammad; Maqsood, Zahida T; Khan, Khalid Mohammed; Omer, Iman; Choudhary, Muhammad Iqbal

    2009-12-01

    Spectroscopic, enzyme-inhibition, and free-radical scavenging properties of a series of hydrazide ligands and their vanadium(IV) complexes have been investigated. Analytical and spectral data indicate the presence of a dimeric unit with two oxovanadium(IV) ions (VO(2+)) coordinated with two hydrazide ligands along with two water molecules. All complexes are stable in the solid state, but exhibit varying degrees of stability in solution. Binding of the coordinating solvent such as DMSO is indicated at the 6th position of vanadium in the dimeric unit followed by conversion to a monomeric intermediate species, [VOL(DMSO)3]1+ (L = hydrazide ligand). The free hydrazide ligands are inactive against snake venom phosphodiesterase I (SVPD), whereas oxovanadium(IV) complexes of these ligands show varying degrees of inhibition and are found to be non-competitive inhibitors. The superoxide and nitric oxide radical scavenging properties have been determined. Hydrazide ligands are inactive against these free radicals, whereas their V(IV) complexes show varying degrees of inhibition. Structure-activity relationship studies indicate that the electronic and/or steric factors that change the geometry of the complexes play an important role in their inhibitory potential against SVPD and free radicals.

  19. 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.

  20. 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.

  1. Spectroscopic and dielectric properties of liquid water: A molecular dynamics simulation study

    NASA Astrophysics Data System (ADS)

    Bursulaya, Badry D.; Kim, Hyung J.

    1998-09-01

    The spectroscopic and dielectric properties of liquid water under an ambient condition are studied via a molecular dynamics (MD) computer simulation method. By employing the recent TAB/10D potential model [B. D. Bursulaya, J. Jeon, D. A. Zichi, and H. J. Kim, J. Chem. Phys. 108, 3286 (1997)], the evolving solvent electronic structure is incorporated into the simulation. Thus both the induced dipole and polarizability variations of individual water molecules with the fluctuating nuclear configuration are accounted for. The MD results on far-IR absorption, depolarized Raman scattering (DRS) and optical Kerr effect (OKE) spectroscopy are in reasonable agreement with experiments. It is found that the nonlinear electronic response of water to its fluctuating environment plays an important role in the DRS and OKE; it significantly enhances the contribution of the water librational motions to the spectra, compared with that of hindered translations. This indicates that not only molecular dynamics but also accompanying electronic structure modulations are essential to quantitative understanding of various electronic spectroscopy. The effects of H/D isotope substitution are briefly discussed.

  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 studies of carotenoid-to-bacteriochlorophyll energy transfer in LHRC photosynthetic complex from Roseiflexus castenholzii.

    PubMed

    Niedzwiedzki, Dariusz M; Collins, Aaron M; LaFountain, Amy M; Enriquez, Miriam M; Frank, Harry A; Blankenship, Robert E

    2010-07-08

    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, gamma-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 S(1)(2(1)A(g)(-)) 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.

  4. Raman spectroscopic study of Ni/Al 2O 3 catalyst

    NASA Astrophysics Data System (ADS)

    Aminzadeh, A.; Sarikhani-fard, H.

    1999-07-01

    In this article a preliminary Raman spectroscopic study of Ni/Al 2O 3 catalyst of the type used for the steam reformation of methane is reported. With several prepared samples of this catalyst and using FT-Raman and conventional dispersive Raman technique, it is shown how Raman spectroscopy can be used to monitor the exact conditions during the preparation of the catalyst. Raman data shows that despite a strong fluorescence background, some useful information can be obtained. According to these data, when the calcination temperature is raised above 1000°C, the gamma alumina ( γ-Al 2O 3) is converted to alpha alumina ( α-Al 2O 3) as it is expected. It further shows that Ni is not present as NiO: it is probably embedded in the crystal structure of γ-Al 2O 3 as NiAl 2O 4 (the spinel structure) or constituted as a solid solution with Al 2O 3.

  5. 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

  6. 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.

  7. 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

    2011-06-06

    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.

  8. 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).

  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. A spectroscopic study of the globular cluster M28 (NGC 6626)

    NASA Astrophysics Data System (ADS)

    Villanova, S.; Moni Bidin, C.; Mauro, F.; Munoz, C.; Monaco, L.

    2017-01-01

    We present the abundance analysis for a sample of 17 red giant branch stars in the metal-poor globular cluster M28 based on high-resolution spectra. This is the first extensive spectroscopic study of this cluster. We derive abundances of O, Na, Mg, Al, Si, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Ba, La, Ce, and Eu. We find a metallicity of [Fe/H] = -1.29 ± 0.01 and an α-enhancement of +0.34 ± 0.01 (errors on the mean), typical of halo globular clusters in this metallicity regime. A large spread is observed in the abundances of light elements O, Na, and Al. Mg also shows an anti-correlation with Al with a significance of 3σ. The cluster shows a Na-O anti-correlation and a Na-Al correlation. This correlation is not linear but `segmented' and that the stars are not distributed continuously, but form at least three well-separated sub-populations. In this aspect, M28 resembles NGC 2808 that was found to host at least five sub-populations. The presence of a Mg-Al anti-correlation favour massive AGB stars as the main polluters responsible for the multiple-population phenomenon.

  11. 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.

  12. Spectroscopic characterization, antimicrobial activity, DFT computation and docking studies of sulfonamide Schiff bases

    NASA Astrophysics Data System (ADS)

    Mondal, Sudipa; Mandal, Santi M.; Mondal, Tapan Kumar; Sinha, Chittaranjan

    2017-01-01

    Schiff bases synthesised from the condensation of 2-(hydroxy)naphthaldehyde and sulfonamides (sufathiazole (STZ), sulfapyridine (SPY), sulfadiazine (SDZ), sulfamerazine (SMZ) and sulfaguanidine (SGN)) are characterized by different spectroscopic data (FTIR, UV-Vis, Mass, NMR) and two of them, (E)-4-(((2-hydroxynaphthalen-1-yl)methylene)amino)-N-(thiazol-2-yl)benzenesulfonamide (1a) and (E)-N-(diaminomethylene)-4-(((2-hydroxynaphthalen-1-yl)methylene)amino)benzenesulfonamide (1e) have been confirmed by single crystal X-ray structure determination. Antimicrobial activities of the Schiff bases have been evaluated against certified and resistant Gram positive (Staphylococcus aureus, Enterococcus facelis) and Gram negative (Streptococcus pyogenes, Salmonella typhi, Shigella dysenteriae, Shigella flexneri, Klebsiella pneumonia) pathogens. Performance of Schiff base against the resistant pathogens are better than standard stain and MIC data lie 32-128 μg/ml while parent sulfonamides are effectively inactive (MIC >512 μg/ml). The DFT optimized structures of the Schiff bases have been used to accomplish molecular docking studies with DHPS (dihydropteroate synthase) protein structure (downloaded from Protein Data Bank) to establish the most preferred mode of interaction. ADMET filtration, Cytotoxicity (MTT assay) and haemolysis assay have been examined for evaluation of druglike character.

  13. {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.

  14. Studies of interaction of emodin and DNA in the presence of ethidium bromide by spectroscopic method.

    PubMed

    Bi, Shuyun; Zhang, Hanqi; Qiao, Chunyu; Sun, Ying; Liu, Chunming

    2008-01-01

    Emodin interacting with deoxyribonucleic acid (DNA) has been studied by different spectroscopic techniques, such as fluorescence, ultraviolet and visible (UV-vis), and fourier transform infared (FT-IR) spectroscopies, using ethidium bromide (EB) as a fluorescence probe of DNA. The decrease in the fluorescence of DNA-EB system on addition of emodin shows that the fluorescence quenching of DNA-EB complex by emodin occurs. The binding constants of emodin with DNA in the presence of EB are 6.02x10(4), 9.20x10(4) and 1.17x10(5)Lmol(-1) at 20, 35 and 50 degrees C, respectively. FT-IR spectrum further suggests that both the phosphate groups and the bases of DNA react with emodin. The reaction of DNA with emodin in the presence of EB is affected by ionic strength and temperature. The values of melting temperature (T(m)) of DNA-EB complex and emodin-DNA-EB complexes were determined, respectively. From the experiment evidences, the major binding mode of emodin with DNA should be the groove binding.

  15. Spectroscopic Studies of Cyclopentane under Extreme Conditions and Implications for the P-T Phase Diagram

    NASA Astrophysics Data System (ADS)

    Ma, Chunli; Liu, Zhenxian; Cui, Qiliang; Hemley, Russell

    2013-06-01

    Infrared (IR) spectroscopy and Raman scattering combined with diamond anvil cell (DAC) and cryogenic techniques have been employed to investigate cyclopentane up to 4 GPa in the temperature range of 100-350 K and isothermal compression up to 84 GPa at room temperature. Four phases including liquid, plastic phases I and II, and truly crystalline phase III are clearly identified in the P-T range studied based on the changes of the ring breathing mode and CH2 rocking modes. The phase diagram is extended to the pressure and temperature range of 0 - 4.0 GPa and 105 - 350 K. Further compression at room temperature up to 84 GPa, another high-pressure phase (IV) is observed based on the appearance of low frequency peaks related to the lattice vibrational modes in the synchrotron far-IR spectra. The spectroscopic results indicate that cyclopentane persists the orientation ordered crystalline phase up to 84 GPa at room temperature. This work was supported by NSF (DMR-0805056; EAR 06-49658, COMPRES) and DOE/ NNSA (DE-FC03-03N00144, CDAC). NSLS is supported by the DOE/BES (DE-AC02-98CH10886).

  16. 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.

  17. 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.

  18. A spectroscopic study of uranyl-cytochrome b5/cytochrome c interactions.

    PubMed

    Sun, Mei-Hui; Liu, Shuang-Quan; Du, Ke-Jie; Nie, Chang-Ming; Lin, Ying-Wu

    2014-01-24

    Uranium is harmful to human health due to its radiation damage and the ability of uranyl ion (UO2(2+)) 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 UO2(2+) 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.

  19. Chiral lactic hydrazone derivatives as potential bioactive antibacterial agents: Synthesis, spectroscopic, structural and molecular docking studies

    NASA Astrophysics Data System (ADS)

    Noshiranzadeh, Nader; Heidari, Azam; Haghi, Fakhri; Bikas, Rahman; Lis, Tadeusz

    2017-01-01

    A series of novel chiral lactic-hydrazone derivatives were synthesized by condensation of (S)-lactic acid hydrazide with salicylaldehyde derivatives and characterized by elemental analysis and spectroscopic studies (FT-IR, 1H NMR and 13C NMR spectroscopy). The structure of one compound was determined by single crystal X-ray analysis. Antibacterial activity of the synthesized compounds was studied against Staphylococcus aureus, Streptococcus pneumonia, Escherichia coli and Pseudomonas aeruginosa as bacterial cultures by broth microdilution method. All of the synthesized compounds showed good antibacterial activity with MIC range of 64-512 μg/mL. Compounds (S,E)-2-hydroxy-N-(2-hydroxy-5-nitrobenzylidene)propanehydrazide (5) and (S,E)-2-hydroxy-N-((3-hydroxy-5-(hydroxymethyl)-2-methylpyridin-4-yl)propanehydrazide (7) were the most effective antibacterial derivatives against S. aureus and E. coli respectively with a MIC value of 64 μg/mL. Bacterial biofilm formation assay showed that these compounds significantly inhibited biofilm formation of P. aeruginosa. Also, in silico molecular docking studies were performed to show lipoteichoic acid synthase (LtaS) inhibitory effect of lactic hydrazone derivatives. The association between electronic and structural effects of some substituents on the benzylidene moiety and the biological activity of these chiral compounds were studied. Structural studies show that compound with higher hydrogen bonding interactions show higher antibacterial activity. The results show chiral hydrazone derivatives based on lactic acid hydrazide could be used as potential lead compounds for developing novel antibacterial agents.

  20. 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.