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Sample records for absorption spectroscopic characterization

  1. Characterization of red sandalwood by ICP-MS analysis, optical absorption and EPR spectroscopic methods

    NASA Astrophysics Data System (ADS)

    Reddy, S. L.; Reddy, N. C. G.; Reddy, R. R. S.; Reddy, G. S.; Rao, P. S.; Reddy, B. J.; Frost, R. L.

    2006-09-01

    Red sandalwood sample was subjected to ICP-mass spectrometer analysis for the determination of minor elements. The ash of the sample was also analysed for the presence of major elements. The minor elements present include Cu (281.256), Ba (3722.064), Sr (6365.482), Rb (45.285), Ce (49.863), Zn (375.433) and Pb (80.944) all in ppt. The major elements detected are Cd, Fe, Mn and Ni. Optical absorption spectrum indicates that Fe(III) and Ni(II) are in tetragonal distortion with octahedral geo-metry. ESR (electron spin resonance) spectral analysis also confirms Fe(III) in tetragonal distortion, and the g-values observed for Fe(III) are 6.52, 2.63 and 1.92 and for Mn(II) is 1.99. NIR spectrum is due to carbonate overtones and harmonics and water fundamentals.

  2. Spectroscopic characterization of Nd:Y2O3: application toward a differential absorption lidar system for remote sensing of ozone

    NASA Astrophysics Data System (ADS)

    Walsh, Brian M.; McMahon, John M.; Edwards, William C.; Barnes, Norman P.; Equall, Randy W.; Hutcheson, Ralph L.

    2002-12-01

    Neodymium-doped yttria (Nd:Y2O3) is investigated as a solid-state laser material for frequency-tripled generation of ultraviolet laser wavelengths for use in remote sensing of ozone. Emphasis is placed both on the spectroscopy of the fundamental wavelengths at ~0.914 ?m and ~0.946 ?m to assess their feasibility for laser oscillation and on the absorption spectroscopy in the 0.8-?m wavelength region for determination of suitable pump sources. The temperature dependence of the emission and absorption characteristics of Nd:Y2O3 are examined, since aggressive cooling may be required for efficient ~0.914-?m lasing due to its quasi four-level nature. Data for flash-lamp-pumped laser performance on the 4F3/2-->4I11/2 is presented for Nd:Y2O3 and compared with Nd:YAG. Diode-pumped threshold-fluence and threshold-pump energy estimates for Nd:Y2O3 lasing on the 4F3/2-->4I9/2 at 0.914 ?m and 0.946 ?m are calculated based on the data presented here. The measurements presented here for the Nd:Y2O3 indicate favorable absorption and emission properties. Favorable absorption properties in the ~0.8-?m pump wavelength are compatible with a variety of potential pump sources. Favorable emission properties at reduced temperatures near 150 K indicate that Nd:Y2O3 operating at 0.914 ?m and 0.946 ?m will have normal-mode laser thresholds similar to that of room-temperature Nd:YAG operating at 0.946 ?m. In Q-switched operation, however, Nd:Y2O3 is predicted to exceed the performance of Nd:YAG due to the lower 1.06/0.94 cross-section ratio, which helps to limit amplified spontaneous-emission effects. Although Nd:Y2O3 is not a new material, it has not been the topic of study due to growth problems associated with its high melting point. New advances in growth techniques and the favorable spectroscopic features of Nd:Y2O3 have inspired a new examination of this material.

  3. Ultraviolet-Absorption Spectroscopic Biofilm Monitor

    NASA Technical Reports Server (NTRS)

    Micheels, Ronald H.

    2004-01-01

    An ultraviolet-absorption spectrometer system has been developed as a prototype instrument to be used in continuous, real-time monitoring to detect the growth of biofilms. Such monitoring is desirable because biofilms are often harmful. For example, biofilms in potable-water and hydroponic systems act as both sources of pathogenic bacteria that resist biocides and as a mechanism for deterioration (including corrosion) of pipes. Biofilms formed from several types of hazardous bacteria can thrive in both plant-growth solutions and low-nutrient media like distilled water. Biofilms can also form in condensate tanks in air-conditioning systems and in industrial heat exchangers. At present, bacteria in potable-water and plant-growth systems aboard the space shuttle (and previously on the Mir space station) are monitored by culture-plate counting, which entails an incubation period of 24 to 48 hours for each sample. At present, there are no commercially available instruments for continuous monitoring of biofilms in terrestrial or spaceborne settings.

  4. Characterization of the physico-chemical properties of polymeric materials for aerospace flight. [differential thermal and atomic absorption spectroscopic analysis of nickel cadmium batteries

    NASA Technical Reports Server (NTRS)

    Rock, M.

    1981-01-01

    Electrodes and electrolytes of nickel cadmium sealed batteries were analyzed. Different thermal analysis of negative and positive battery electrodes was conducted and the temperature ranges of occurrence of endotherms indicating decomposition of cadmium hydroxide and nickel hydroxide are identified. Atomic absorption spectroscopy was used to analyze electrodes and electrolytes for traces of nickel, cadmium, cobalt, and potassium. Calibration curves and data are given for each sample analyzed. Instrumentation and analytical procedures used for each method are described.

  5. Vibrational spectroscopic characterization of fluoroquinolones

    NASA Astrophysics Data System (ADS)

    Neugebauer, U.; Szeghalmi, A.; Schmitt, M.; Kiefer, W.; Popp, J.; Holzgrabe, U.

    2005-05-01

    Quinolones are important gyrase inhibitors. Even though they are used as active agents in many antibiotics, the detailed mechanism of action on a molecular level is so far not known. It is of greatest interest to shed light on this drug-target interaction to provide useful information in the fight against growing resistances and obtain new insights for the development of new powerful drugs. To reach this goal, on a first step it is essential to understand the structural characteristics of the drugs and the effects that are caused by the environment in detail. In this work we report on Raman spectroscopical investigations of a variety of gyrase inhibitors (nalidixic acid, oxolinic acid, cinoxacin, flumequine, norfloxacin, ciprofloxacin, lomefloxacin, ofloxacin, enoxacin, sarafloxacin and moxifloxacin) by means of micro-Raman spectroscopy excited with various excitation wavelengths, both in the off-resonance region (532, 633, 830 and 1064 nm) and in the resonance region (resonance Raman spectroscopy at 244, 257 and 275 nm). Furthermore DFT calculations were performed to assign the vibrational modes, as well as for an identification of intramolecular hydrogen bonding motifs. The effect of small changes in the drug environment was studied by adding successively small amounts of water until physiological low concentrations of the drugs in aqueous solution were obtained. At these low concentrations resonance Raman spectroscopy proved to be a useful and sensitive technique. Supplementary information was obtained from IR and UV/vis spectroscopy.

  6. Tunable fiber ring laser absorption spectroscopic sensors for gas detection

    NASA Astrophysics Data System (ADS)

    Zheng, Shijie; Zhu, Yinian; Krishnaswamy, Sridhar

    2013-04-01

    Fiber-optic gas sensing techniques are commonly based on the recognition of a wide range of chemical species from characteristic absorption, fluorescence or Raman-scattering spectra signatures. By tuning over the vibrational lines of species in the path of laser beam, tunable diode laser gas sensors measure signal spectroscopic intensity, gas concentration, and other properties. However, they have limitations of bulk architecture, small change of signal on top of large background, and low sensitivity of direct absorption. Here we report the fabrication and optical measurements of tunable Er-doped fiber ring laser absorption spectroscopic sensor featuring a gas cell that is a segment of photonic crystal fiber (PCF) with a long-period grating (LPG) inscribed. The tunable laser beam is coupled into the cladding of the PCF by the LPG where the gas in air holes absorbs light. The light travels along the PCF cladding and reflects at the end of the fiber where a silver film is coated as a mirror at one end facet. The light propagates back within cladding and passes through the gas one more time thus increasing the interaction length. This light is finally recoupled into the fiber core for intensity measurement. The proposed fiber gas sensors have been experimentally used for ammonia (NH3) concentration detection. They show excellent sensitivity and selectivity, and are minimally affected by temperature and/or humidity changes. The sensors using PCF-LPG gas cell are simple to fabricate, cost-effective, and are deployed for a variety of applications not possible using conventional optical fibers.

  7. Characterization of semicrystalline polymers after nanoimprint by spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Wang, Si; Rond, Johannes; Steinberg, Christian; Papenheim, Marc; Scheer, Hella-Christin

    2016-02-01

    Semicrystalline Reg-P3HT (regio-regular poly-3-hexylthiophene) is a promising material for organic electronics. It features relatively high charge mobility and enables easy preparation because of its solubility. Due to its high optical and electrical anisotropy, the size, number and orientation of the ordered domains are important for applications. To control these properties without limitation from crystalline domains existing after spin coating, thermal nanoimprint is performed beyond the melting point. The state of the art of measurement to analyze the complex morphology is X-ray diffraction (XRD). We address an alternative measurement method to characterize the material by its optical properties, spectroscopic ellipsometry. It provides information on the degree of order from the typical fingerprint absorption spectrum. In addition, when the material is modeled as a uniaxial layer, an anisotropy factor can be derived. The results obtained from spectroscopic ellipsometry are in accordance with those from XRD. In particular, spectroscopic ellipsometry is able to distinguish between order along the backbone and order in π- π stacking direction, which is important with respect to conductivity.

  8. Spectroscopic Methods of Remote Sensing for Vegetation Characterization

    NASA Astrophysics Data System (ADS)

    Kokaly, R. F.

    2013-12-01

    Imaging spectroscopy (IS), often referred to as hyperspectral remote sensing, is one of the latest innovations in a very long history of spectroscopy. Spectroscopic methods have been used for understanding the composition of the world around us, as well as, the solar system and distant parts of the universe. Continuous sampling of the electromagnetic spectrum in narrow bands is what separates IS from previous forms of remote sensing. Terrestrial imaging spectrometers often have hundreds of channels that cover the wavelength range of reflected solar radiation, including the visible, near-infrared (NIR), and shortwave infrared (SWIR) regions. In part due to the large number of channels, a wide variety of methods have been applied to extract information from IS data sets. These can be grouped into several broad classes, including: multi-channel indices, statistical procedures, full spectrum mixing models, and spectroscopic methods. Spectroscopic methods carry on the more than 150 year history of laboratory-based spectroscopy applied to material identification and characterization. Spectroscopic methods of IS relate the positions and shapes of spectral features resolved by airborne and spaceborne sensors to the biochemical and physical composition of vegetation in a pixel. The chlorophyll 680nm, water 980nm, water 1200nm, SWIR 1700nm, SWIR 2100nm, and SWIR 2300nm features have been the subject of study. Spectral feature analysis (SFA) involves isolating such an absorption feature using continuum removal (CR) and calculating descriptors of the feature, such as center position, depth, width, area, and asymmetry. SFA has been applied to quantify pigment and non-pigment biochemical concentrations in leaves, plants, and canopies. Spectral feature comparison (SFC) utilizes CR of features in each pixel's spectrum and linear regression with continuum-removed features in reference spectra in a library of known vegetation types to map vegetation species and communities. SFC has been applied to map the distributions of minerals in soils and rocks; however, its application to characterize vegetation cover has been less widespread than SFA. Using IS data and the USGS Processing Routines in IDL for Spectroscopic Measurements (PRISM; http://pubs.usgs.gov/of/2011/1155/), this talk will examine requirements for and limitations in applying SFA and SFC to characterize vegetation. A time series of Airborne Visible/InfraRed Imaging Spectrometer (AVIRIS) data collected in the marshes of Louisiana following the Deepwater Horizon oil spill will be used to examine the impact of varying leaf water content on the shapes of the SWIR 1700, 2100, and 2300 nm features and the implications of these changes on vegetation identification and biochemical estimation. The USGS collection of HyMap data over Afghanistan, the largest terrestrial coverage of IS data to date, will be used to demonstrate the characterization of vegetation in arid and semi-arid regions, in which chlorophyll absorption is often weak and soil and rock mineral absorption features overlap vegetation features. Hyperion data, overlapping the HyMap data, will be presented to illustrate the complications that arise when signal-to-noise is low. The benefits of and challenges to applying a spectroscopic remote sensing approach to imaging spectrometer data will be discussed.

  9. Spectroscopic characterization of genetically modified flax fibers

    NASA Astrophysics Data System (ADS)

    Dymińska, L.; Gągor, A.; Hanuza, J.; Kulma, A.; Preisner, M.; Żuk, M.; Szatkowski, M.; Szopa, J.

    2014-09-01

    The principal goal of this paper is an analysis of flax fiber composition. Natural and genetically modified flax fibers derived from transgenic flax have been analyzed. Development of genetic engineering enables to improve the quality of fibers. Three transgenic plant lines with different modifications were generated based on fibrous flax plants as the origin. These are plants with: silenced cinnamyl alcohol dehydrogenase (CAD) gene; overexpression of polygalacturonase (PGI); and expression of three genes construct containing β-ketothiolase (phb A), acetoacetyl-CoA reductase (phb B), and poly-3-hydroxybutyric acid synthase (phb C). Flax fibers have been studied by FT-IR spectroscopy. The integral intensities of the IR bands have been used for estimation of the chemical content of the normal and transgenic flaxes. The spectroscopic data were compared to those obtained from chemical analysis of flax fibers. X-ray studies have been used to characterize the changes of the crystalline structure of the flax cellulose fibers.

  10. Spectroscopic characterizations of organic/inorganic nanocomposites

    NASA Astrophysics Data System (ADS)

    Govani, Jayesh R.

    2009-12-01

    In the present study, pure and 0.3 wt%, 0.4 wt%, as well as 0.5 wt% L-arginine doped potassium dihydrogen phosphate (KDP) crystals were grown using solution growth techniques and further subjected to infrared (IR) absorption and Raman studies for confirmation of chemical group functionalization for investigating the incorporation mechanism of the L-arginine organic material into the KDP crystal structure. Infrared spectroscopic analysis suggests that structural changes are occurring for the L-arginine molecule as a result of its interaction with the KPD crystal. Infrared spectroscopic technique confirms the disturbance of the N-H, C-H and C-N bonds of the amino acid, suggesting successful incorporation of L-arginine into the KDP crystals. Raman analysis also reveals modification of the N-H, C-H and C-N bonds of the amino acid, implying successful inclusion of L-arginine into the KDP crystals. With the help of Gaussian software, a prediction of possible incorporation mechanisms of the organic material was obtained from comparison of the simulated infrared and Raman vibrational spectra with the experimental results. Furthermore, we also studied the effect of L-arginine doping on the thermal stability of the grown KDP crystal by employing Thermo gravimetric analysis (TGA). TGA suggests that increasing the level of L-arginine doping speeds the decomposition process and it weakens the KDP crystal, which indicates successful doping of the KDP crystals with L-arginine amino acid. Urinary stones are one of the oldest and most widely spread diseases in humans, animals and birds. Many remedies have been employed through the ages for the treatment of urinary stones. Recent medicinal measures reflect the modern advances, which are based on surgical removal, percutaneous techniques and extracorporeal shock wave lithotripsy (ESWL). Although these procedures are valuable, they are quite expensive for most people. Furthermore, recurrence of these diseases is awfully frequent with these procedures and the patients have to be subjected to careful follow up for several years. In contrast, in traditional therapeutic systems, most of the remedies were taken from plants and they proved to be helpful. However, the rationale behind their use is not thoroughly established through systematic pharmacological and clinical studies. In this regard, in the present investigation, with a view towards acquiring more insights, we have performed a detailed study of kidney stone formation and growth inhibition based on a traditional medicine approach with herbal extracts. The intricacy of calculi formation (i.e. nucleation, transformation, and aggregation) in a natural system such as urine is replicated to a certain extent in the present study by using a simplified single diffusion gel growth technique. Crystals were synthesized in a static gel environment without and with the presence of 1% and 2% concentration of Rotula Aquatica Lour (RAL) herbal extracts and further subjected to Raman, infrared absorption, X-ray photoelectron spectroscopy (XPS), and photoluminescence to analyze the effects of RAL on the growth of manganese-based calculi. Raman spectroscopy clearly provided an indication of the newberyite type of crystal as well as information on the chemical interaction between crystal and inhibitor. It also indicates the presence of organic components due to the RAL plant material. Infrared absorption spectroscopy indicates the presence of a strong reflecting component in the inhibitor as well as the newberyite type of crystal. XPS results indicated the presence of metallic zinc in the crystal with inhibitor. Furthermore, a considerable increase in the intensity of the magnesium and oxygen lines are noticed with the addition of the herbal extract, which suggest that the inhibitor chemical composition includes a substantial quantity of Mg and O. XPS analysis also demonstrates the presence of modified phosphorus oxidation states and suggest that they might make a contribution, too. The photoluminescence spectra of the crystal with inhibitor indicate the presence of chlorophyll, and hence, confirm the presence of Mg. This study provides evidence of Mg- and Zn-related inhibition of urinary calculi formation with the addition of RAL herbal extract, contributing, from the spectroscopic point of view, to an intricate subject. Our present investigation might serve as an important source of information on this tantalizing and multifaceted problem, which is not yet completely understood. (Abstract shortened by UMI.)

  11. Absorption and emission spectroscopic characterisation of 8-amino-riboflavin

    NASA Astrophysics Data System (ADS)

    Tyagi, A.; Zirak, P.; Penzkofer, A.; Mathes, T.; Hegemann, P.; Mack, M.; Ghisla, S.

    2009-10-01

    The flavin dye 8-amino-8-demethyl- D-riboflavin (AF) in the solvents water, DMSO, methanol, and chloroform/DMSO was studied by absorption and fluorescence spectroscopy. The first absorption band is red-shifted compared to riboflavin, and blue-shifted compared to roseoflavin (8-dimethylamino-8-demethyl-D-riboflavin). The fluorescence quantum yield of AF in the studied solvents varies between 20% and 50%. The fluorescence lifetimes were found to be in the 2-5 ns range. AF is well soluble in DMSO, weakly soluble in water and methanol, and practically insoluble in chloroform. The limited solubility causes AF aggregation, which was seen in differences between measured absorption spectra and fluorescence excitation spectra. Light scattering in the dye absorption region is discussed and approximate absorption cross-section spectra are determined from the combined measurement of transmission and fluorescence excitation spectra. The photo-stability of AF was studied by prolonged light exposure. The photo-degradation routes of AF are discussed.

  12. Opto-nanomechanical spectroscopic material characterization

    SciTech Connect

    Tetard, Laurene; Passian, Ali; Farahi, R. H.; Thundat, Thomas; Davison, Brian H.

    2015-08-10

    Cellulosic ethanol is a biofuel of considerable potential in the search for sustainable and renewable bioenergy [1,2]. However, while rich in carbohydrates [3], the plant cell walls exhibit a natural resistance to complex phenotype treatments such as enzymatic microbial deconstruction, heat and acid treatments that can remove the lignin polymers from cellulose before hydrolysis [5]. Noninvasive physical and chemical characterization of the cell walls and the effect of such treatments on biomass are challenging but necessary to understand and overcome such resistance [6]. Although lacking chemical recognition in their traditional forms, the various emerging modalities of nano-mechanical [7] and opto-nano-mechanical [8] force microscopies [9,10] provide a superb window into the needed nanoscale material characterization [6]. Infrared absorption spectroscopy is a powerful, non- destructive and ultra-sensitive technique that can provide the needed molecular fingerprinting but the photothermal channel is delocalized and thus lacks spatial resolution. Utilizing the emerging dynamic concepts of mode synthesizing atomic force microscopy (MSAFM) [11] and virtual resonance [12], we introduce a hybrid photonic and nanomechanical force microscopy (hp-MSAFM) with molecular recognition and characterize the extraction, holopulping and acid treatment of biomass. We present spatially and spectrally resolved cell wall images that reveal both the morphological and the compositional alterations of the cell walls. The measured biomolecular traits are in agreement with chemical maps obtained with infrared and confocal Raman micro-spectroscopies of the same samples. The presented findings should prove highly relevant in fields such as cancer research [13], nanotoxicity [14], energy storage and production [15], where morphological, chemical and subsurface studies of nanocomposites [16], nanoparticle uptake by cells [14], and nanoscale quality control [17] are in demand.

  13. Opto-nanomechanical spectroscopic material characterization

    DOE PAGESBeta

    Tetard, Laurene; Passian, Ali; Farahi, R. H.; Thundat, Thomas; Davison, Brian H.

    2015-08-10

    Cellulosic ethanol is a biofuel of considerable potential in the search for sustainable and renewable bioenergy [1,2]. However, while rich in carbohydrates [3], the plant cell walls exhibit a natural resistance to complex phenotype treatments such as enzymatic microbial deconstruction, heat and acid treatments that can remove the lignin polymers from cellulose before hydrolysis [5]. Noninvasive physical and chemical characterization of the cell walls and the effect of such treatments on biomass are challenging but necessary to understand and overcome such resistance [6]. Although lacking chemical recognition in their traditional forms, the various emerging modalities of nano-mechanical [7] and opto-nano-mechanicalmore » [8] force microscopies [9,10] provide a superb window into the needed nanoscale material characterization [6]. Infrared absorption spectroscopy is a powerful, non- destructive and ultra-sensitive technique that can provide the needed molecular fingerprinting but the photothermal channel is delocalized and thus lacks spatial resolution. Utilizing the emerging dynamic concepts of mode synthesizing atomic force microscopy (MSAFM) [11] and virtual resonance [12], we introduce a hybrid photonic and nanomechanical force microscopy (hp-MSAFM) with molecular recognition and characterize the extraction, holopulping and acid treatment of biomass. We present spatially and spectrally resolved cell wall images that reveal both the morphological and the compositional alterations of the cell walls. The measured biomolecular traits are in agreement with chemical maps obtained with infrared and confocal Raman micro-spectroscopies of the same samples. The presented findings should prove highly relevant in fields such as cancer research [13], nanotoxicity [14], energy storage and production [15], where morphological, chemical and subsurface studies of nanocomposites [16], nanoparticle uptake by cells [14], and nanoscale quality control [17] are in demand.« less

  14. Identification and spectroscopic characterization of nonheme iron(III) hypochlorite intermediates.

    PubMed

    Draksharapu, Apparao; Angelone, Davide; Quesne, Matthew G; Padamati, Sandeep K; Gmez, Laura; Hage, Ronald; Costas, Miquel; Browne, Wesley R; de Visser, Sam P

    2015-03-27

    Fe(III)-hypohalite complexes have been implicated in a wide range of important enzyme-catalyzed halogenation reactions including the biosynthesis of natural products and antibiotics and post-translational modification of proteins. The absence of spectroscopic data on such species precludes their identification. Herein, we report the generation and spectroscopic characterization of nonheme Fe(III)-hypohalite intermediates of possible relevance to iron halogenases. We show that Fe(III)-OCl polypyridylamine complexes can be sufficiently stable at room temperature to be characterized by UV/Vis absorption, resonance Raman and EPR spectroscopies, and cryo-ESIMS. DFT?methods rationalize the pathways to the formation of the Fe(III)-OCl, and ultimately Fe(IV)=O, species and provide indirect evidence for a short-lived Fe(II)-OCl intermediate. The species observed and the pathways involved offer insight into and, importantly, a spectroscopic database for the investigation of iron halogenases. PMID:25663379

  15. 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.

  16. IR absorption spectroscopic study of mixed cobalt substituted lithium ferrites

    NASA Astrophysics Data System (ADS)

    Sawant, V. S.; Bagade, A. A.; Mohite, S. V.; Rajpure, K. Y.

    2014-10-01

    The IR spectra of Li0.5-(x/2)CoxFe2.5-(x/2)O4 ferrite samples (0?x?0.6) prepared by solution combustion method have been reported. The influence of Co substitution is verified. XRD studies confirm the spinel phase formation of ferrites. Lattice constant varies linearly from 8.31 (x=0) to 8.35 (x=0.6) with composition. Evidence of two absorption bands in the IR spectra (below 800 cm-1) reveals the characteristic feature of spinel ferrite. The IR spectra featured additional three absorption bands around 550, 670 and 705 cm-1 for the samples x=0.1 and x=0.6. Absence of bands splitting specifies that Fe ions do not exist in excess form. It is found that high frequency band (?1), due to tetrahedral (A) group, lies at around 600 cm-1 and low frequency band (?2), due to octahedral (B) group, around 450 cm-1. The positions of bands are found to be composition dependent. The IR bands due to tetrahedral complexes shift slightly towards high frequency side with composition upto x=0.4 where as that due to octahedral complexes shift towards lower frequency side with x. Based on the data of absorption bands, force constants (kt, ko) and bond lengths (RA, RB) were estimated. Compositional dependence of force constants is explained on the basis of cation-oxygen bond distances of respective sites and cation distribution.

  17. Spectroscopic observations of magnesium absorption gradients in six elliptical galaxies

    NASA Astrophysics Data System (ADS)

    Couture, Jean; Hardy, Eduardo

    1988-09-01

    The authors present Mg2 absorption strengths for six early-type galaxies obtained with Mont Mgantic's long-slit spectrograph and a panoramic photon-counting detector system. The gradients have been measured to more than one effective radius for NGC 1052, 3379, 4365, 4406, 4621, and 7332 along the major axis and, in three cases, also along the minor axis. The data are presented in tabular and graphical form. The spectral variations have been mapped in two different adimensional radial coordinate systems. The gradients were found to be very similar for a given representation for all galaxies studied. The gradients are also similar to those derived from a representation of the available published data in the same coordinate systems. Using the currently available abundance versus Mg2 strength calibrations, the authors confirm that abundance varies by a factor ?2 within one effective radius for giant early-type galaxies.

  18. Spectroscopic characterization of isomerization transition states

    NASA Astrophysics Data System (ADS)

    Baraban, Joshua H.; Changala, P. Bryan; Mellau, Georg Ch.; Stanton, John F.; Merer, Anthony J.; Field, Robert W.

    2015-12-01

    Transition state theory is central to our understanding of chemical reaction dynamics. We demonstrate a method for extracting transition state energies and properties from a characteristic pattern found in frequency-domain spectra of isomerizing systems. This patterna dip in the spacings of certain barrier-proximal vibrational levelscan be understood using the concept of effective frequency, ?eff. The method is applied to the cis-trans conformational change in the S1 state of C2H2 and the bond-breaking HCN-HNC isomerization. In both cases, the barrier heights derived from spectroscopic data agree extremely well with previous ab initio calculations. We also show that it is possible to distinguish between vibrational modes that are actively involved in the isomerization process and those that are passive bystanders.

  19. Spectroscopic characterization of isomerization transition states.

    PubMed

    Baraban, Joshua H; Changala, P Bryan; Mellau, Georg Ch; Stanton, John F; Merer, Anthony J; Field, Robert W

    2015-12-11

    Transition state theory is central to our understanding of chemical reaction dynamics. We demonstrate a method for extracting transition state energies and properties from a characteristic pattern found in frequency-domain spectra of isomerizing systems. This pattern-a dip in the spacings of certain barrier-proximal vibrational levels-can be understood using the concept of effective frequency, ?(eff). The method is applied to the cis-trans conformational change in the S1 state of C2H2 and the bond-breaking HCN-HNC isomerization. In both cases, the barrier heights derived from spectroscopic data agree extremely well with previous ab initio calculations. We also show that it is possible to distinguish between vibrational modes that are actively involved in the isomerization process and those that are passive bystanders. PMID:26659051

  20. Catalog of Narrow Mg II Absorption Lines in the Baryon Oscillation Spectroscopic Survey

    NASA Astrophysics Data System (ADS)

    Chen, Zhi-Fu; Gu, Qiu-Sheng; Chen, Yan-Mei

    2015-12-01

    Using the Data Release 9 Quasar spectra from the Baryonic Oscillation Spectroscopic Survey, which does not include quasar spectra from the Sloan Digital Sky Survey Data Release 7, we detect narrow Mg ii λλ2796, 2803 absorption doublets in the spectral data redward of 1250 Å (quasar rest frame) until the red wing of the Mg ii λ2800 emission line. Our survey is limited to quasar spectra with a median signal-to-noise ratio < {{S}}/{{N}}> ≥slant 4 pixel-1 in the surveyed spectral region, resulting in a sample that contains 43,260 quasars. We have detected a total of 18,598 Mg ii absorption doublets with 0.2933 ≤ zabs ≤ 2.6529. About 75% of absorbers have an equivalent width at rest frame of {W}rλ 2796≥slant 1 \\mathringA . About 75% of absorbers have doublet ratios ({DR}={W}rλ 2796/{W}rλ 2803) in the range of 1 ≤ DR ≤ 2, and about 3.2% lie outside the range of 1 - σDR ≤ DR ≤ 2 + σDR. We characterize the detection false positives/negatives by the frequency of detected Mg ii absorption doublets in the limits of the S/N of the spectral data. The S/N = 4.5 limit is assigned a completeness fraction of 53% and tends to be complete when the S/N is greater than 4.5. The redshift number densities of all of the detected Mg ii absorbers moderately increase from z ≈ 0.4 to z ≈ 1.5, which parallels the evolution of the cosmic star formation rate density. Limiting our investigation to those quasars whose emission redshift can be determined from narrow emission lines, the relative velocities (β) of Mg ii absorbers have a complex distribution which probably consists of three classes of Mg ii absorbers: (1) cosmologically intervening absorbers; (2) environmental absorbers that reside within the quasar host galaxies or galaxy clusters; (3) quasar outflow absorbers. After subtracting contributions from cosmologically intervening absorbers and environmental absorbers, the β distribution of the Mg iiabsorbers might mainly be contributed by the quasar outflow absorbers and peaks at υ ≈ 1500 km s-1. This peak velocity is lower than the value of 2000 km s-1 found in statistical analysis of C iv absorbers.

  1. Extraction, Purification, and Spectroscopic Characterization of a Mixture of Capsaicinoids

    ERIC Educational Resources Information Center

    Wagner, Carl E.; Cahill, Thomas M.; Marshall, Pamela A.

    2011-01-01

    This laboratory experiment provides a safe and effective way to instruct undergraduate organic chemistry students about natural-product extraction, purification, and NMR spectroscopic characterization. On the first day, students extract dried habanero peppers with toluene, perform a pipet silica gel column to separate carotenoids from…

  2. Extraction, Purification, and Spectroscopic Characterization of a Mixture of Capsaicinoids

    ERIC Educational Resources Information Center

    Wagner, Carl E.; Cahill, Thomas M.; Marshall, Pamela A.

    2011-01-01

    This laboratory experiment provides a safe and effective way to instruct undergraduate organic chemistry students about natural-product extraction, purification, and NMR spectroscopic characterization. On the first day, students extract dried habanero peppers with toluene, perform a pipet silica gel column to separate carotenoids from

  3. Methodical study on plaque characterization using integrated vascular ultrasound, strain and spectroscopic photoacoustic imaging

    NASA Astrophysics Data System (ADS)

    Graf, Iulia M.; Su, Jimmy; Yeager, Doug; Amirian, James; Smalling, Richard; Emelianov, Stanislav

    2011-03-01

    Carotid atherosclerosis has been identified as a potential risk factor for cerebrovascular events, but information about its direct effect on the risk of recurrent stroke is limited due to incomplete diagnosis. The combination of vascular ultrasound, strain rate and spectroscopic photoacoustics could improve the timely diagnosis of plaque status and risk of rupturing. Current ultrasound techniques can noninvasively image the anatomy of carotid arteries. The spatio-temporal variation in displacement of different regions within the arterial wall can be derived from ultrasound radio frequency data; therefore an ultrasound based strain rate imaging modality can be used to reveal changes in arterial mechanical properties. Additionally, spectroscopic photoacoustic imaging can provide information on the optical absorption properties of arterial tissue and it can be used to identify the location of specific tissue components, such as lipid pools. An imaging technique combining ultrasound, strain rate and spectroscopic photoacoustics was tested on an excised atherosclerotic rabbit aorta. The ultrasound image illustrates inhomogeneities in arterial wall thickness, the strain rate indicates the arterial segment with reduced elasticity and the spectroscopic photoacoustic image illustrates the accumulation of lipids. The results demonstrated that ultrasound, strain rate and spectroscopic photoacoustic imaging are complementary. Thus the integration of the three imaging modalities advances the characterization of atherosclerotic plaques.

  4. Spectroscopic characterization of natural calcite minerals

    NASA Astrophysics Data System (ADS)

    Gunasekaran, S.; Anbalagan, G.

    2007-11-01

    The FT-IR, FT-Raman, NMR spectral data of ten different limestone samples have been compared. FT-IR and FT-Raman spectral data show that calcium carbonate in limestone, principally in the form of calcite, as identified by its main absorption bands at 1426, 1092, 876 and 712 cm -1. The sharp diffractions at the d-spacings, 3.0348, 1.9166 and 1.8796 confirm the presence of calcite structure and the calculated lattice parameters are: a = 4.9781 , c = 17.1188 . The range of 13C chemical shifts for different limestone samples is very small, varying from 198.38 to 198.42 ppm. The observed chemical shifts are consistent with the identical C-O bonding in different limestone samples. 27Al MAS NMR spectra of the samples exhibit a central line at 1 ppm and another line at 60 ppm corresponding to octahedral and tetrahedral Al ions, respectively. The five component resonances were observed in 29Si MAS NMR spectrum of limestone and these resonances were assigned to Si (4 Al), Si (3 Al), Si (2 Al), Si (1 Al) and Si (0 Al) from low field to high field.

  5. Opto-nanomechanical spectroscopic material characterization.

    PubMed

    Tetard, L; Passian, A; Farahi, R H; Thundat, T; Davison, B H

    2015-10-01

    The non-destructive, simultaneous chemical and physical characterization of materials at the nanoscale is an essential and highly sought-after capability. However, a combination of limitations imposed by Abbe diffraction, diffuse scattering, unknown subsurface, electromagnetic fluctuations and Brownian noise, for example, have made achieving this goal challenging. Here, we report a hybrid approach for nanoscale material characterization based on generalized nanomechanical force microscopy in conjunction with infrared photoacoustic spectroscopy. As an application, we tackle the outstanding problem of spatially and spectrally resolving plant cell walls. Nanoscale characterization of plant cell walls and the effect of complex phenotype treatments on biomass are challenging but necessary in the search for sustainable and renewable bioenergy. We present results that reveal both the morphological and compositional substructures of the cell walls. The measured biomolecular traits are in agreement with the lower-resolution chemical maps obtained with infrared and confocal Raman micro-spectroscopies of the same samples. These results should prove relevant in other fields such as cancer research, nanotoxicity, and energy storage and production, where morphological, chemical and subsurface studies of nanocomposites, nanoparticle uptake by cells and nanoscale quality control are in demand. PMID:26258550

  6. Opto-nanomechanical spectroscopic material characterization

    NASA Astrophysics Data System (ADS)

    Tetard, L.; Passian, A.; Farahi, R. H.; Thundat, T.; Davison, B. H.

    2015-10-01

    The non-destructive, simultaneous chemical and physical characterization of materials at the nanoscale is an essential and highly sought-after capability. However, a combination of limitations imposed by Abbe diffraction, diffuse scattering, unknown subsurface, electromagnetic fluctuations and Brownian noise, for example, have made achieving this goal challenging. Here, we report a hybrid approach for nanoscale material characterization based on generalized nanomechanical force microscopy in conjunction with infrared photoacoustic spectroscopy. As an application, we tackle the outstanding problem of spatially and spectrally resolving plant cell walls. Nanoscale characterization of plant cell walls and the effect of complex phenotype treatments on biomass are challenging but necessary in the search for sustainable and renewable bioenergy. We present results that reveal both the morphological and compositional substructures of the cell walls. The measured biomolecular traits are in agreement with the lower-resolution chemical maps obtained with infrared and confocal Raman micro-spectroscopies of the same samples. These results should prove relevant in other fields such as cancer research, nanotoxicity, and energy storage and production, where morphological, chemical and subsurface studies of nanocomposites, nanoparticle uptake by cells and nanoscale quality control are in demand.

  7. Crystallographic and X-ray absorption spectroscopic characterization of Helicobacter pylori UreE bound to Ni2+ and Zn2+ reveal a role for the disordered C-terminal arm in metal trafficking

    PubMed Central

    Banaszak, Katarzyna; Martin-Diaconescu, Vlad; Bellucci, Matteo; Zambelli, Barbara; Rypniewski, Wojciech; Maroney, Michael J.; Ciurli, Stefano

    2012-01-01

    The survival and growth of the pathogen Helicobacter pylori in the gastric acidic environment is ensured by the activity of urease, an enzyme containing two essential Ni2+ ions in the active site. The metallo-chaperone UreE facilitates in vivo Ni2+ insertion into the apo-enzyme. Crystals of apo-HpUreE and its Ni2+ and Zn2+ bound forms were obtained from protein solutions in the absence and presence of the metal ions. The crystal structures of the homodimeric protein, determined at 2.00 (apo), 1.59 (Ni) and 2.52 (Zn) resolution, show the conserved proximal and solvent-exposed His102 residues from two adjacent monomers invariably involved in metal binding. The C-terminal regions of the apo-protein are disordered in the crystal, but acquire significant ordering in the presence of the metal ions due to the binding of His152. The analysis of X-ray absorption spectral data obtained on solutions of Ni2+- and Zn2+-HpUreE provided accurate information of the metal ion environment in the absence of solid-state effects. These results reveal the role of the histidine residues at the protein C-terminus in metal ion binding, and the mutual influence of protein framework and metal ion stereo-electronic properties in establishing coordination number and geometry leading to metal selectivity. PMID:22010876

  8. Solvate structures and spectroscopic characterization of LiTFSI electrolytes.

    PubMed

    Seo, Daniel M; Boyle, Paul D; Sommer, Roger D; Daubert, James S; Borodin, Oleg; Henderson, Wesley A

    2014-11-26

    A Raman spectroscopic evaluation of numerous crystalline solvates with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI or LiN(SO2CF3)2) has been conducted over a wide temperature range. Four new crystalline solvate structures-(PHEN)3:LiTFSI, (2,9-DMPHEN)2:LiTFSI, (G3)1:LiTFSI and (2,6-DMPy)1/2:LiTFSI with phenanthroline, 2,9-dimethyl[1,10]phenanthroline, triglyme, and 2,6-dimethylpyridine, respectively-have been determined to aid in this study. The spectroscopic data have been correlated with varying modes of TFSI(-)Li(+) cation coordination within the solvate structures to create an electrolyte characterization tool to facilitate the Raman band deconvolution assignments for the determination of ionic association interactions within electrolytes containing LiTFSI. It is found, however, that significant difficulties may be encountered when identifying the distributions of specific forms of TFSI(-) anion coordination present in liquid electrolyte mixtures due to the wide range of TFSI(-)Li(+) cation interactions possible and the overlap of the corresponding spectroscopic data signatures. PMID:25345716

  9. 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.

  10. Spectroscopic characterization of femtosecond laser filament in argon gas

    SciTech Connect

    Liu, W.; Bernhardt, J.; Theberge, F.; Chin, S. L.; Chateauneuf, M.; Dubois, J.

    2007-08-01

    We report a spectroscopic approach to measure the plasma density and electron temperature inside a filament created by an intense femtosecond laser pulse in atmospheric pressure argon gas. The technique relies on the proportionality between the Stark broadened argon fluorescence line width due to electron impact and the plasma density, while the electron temperature is determined from the well known Boltzmann plot. The obtained maximum plasma density is about 5.5x10{sup 16} cm{sup -3}, and the electron temperature is about 5800 K. Our method provides a promising and convenient way to characterize the filament for further understanding the fundamental physics and potential applications of filamentation.

  11. Matrix isolation, spectroscopic characterization, and photoisomerization of m-xylylene.

    PubMed

    Neuhaus, Patrik; Grote, Dirk; Sander, Wolfram

    2008-03-12

    A new efficient synthesis of m-xylylene 1 is reported. The diradical 1 was trapped in argon matrices at 10 K and characterized by IR, UV-vis, and EPR spectroscopy. The syntheses reported before only allowed generation of 1 in organic glasses, and the spectroscopic identification was limited to fluorescence and EPR spectroscopy. Diradical 1 proved to be highly photolabile, and irradiation results in the formation of three isomeric hydrocarbons 7, 9, and 11 which could be identified by comparison of their IR spectra with the results of DFT calculations. PMID:18278907

  12. Characterization of cytochrome c as marker for retinal cell degeneration by uv/vis spectroscopic imaging

    NASA Astrophysics Data System (ADS)

    Hollmach, Julia; Schweizer, Julia; Steiner, Gerald; Knels, Lilla; Funk, Richard H. W.; Thalheim, Silko; Koch, Edmund

    2011-07-01

    Retinal diseases like age-related macular degeneration have become an important cause of visual loss depending on increasing life expectancy and lifestyle habits. Due to the fact that no satisfying treatment exists, early diagnosis and prevention are the only possibilities to stop the degeneration. The protein cytochrome c (cyt c) is a suitable marker for degeneration processes and apoptosis because it is a part of the respiratory chain and involved in the apoptotic pathway. The determination of the local distribution and oxidative state of cyt c in living cells allows the characterization of cell degeneration processes. Since cyt c exhibits characteristic absorption bands between 400 and 650 nm wavelength, uv/vis in situ spectroscopic imaging was used for its characterization in retinal ganglion cells. The large amount of data, consisting of spatial and spectral information, was processed by multivariate data analysis. The challenge consists in the identification of the molecular information of cyt c. Baseline correction, principle component analysis (PCA) and cluster analysis (CA) were performed in order to identify cyt c within the spectral dataset. The combination of PCA and CA reveals cyt c and its oxidative state. The results demonstrate that uv/vis spectroscopic imaging in conjunction with sophisticated multivariate methods is a suitable tool to characterize cyt c under in situ conditions.

  13. Characterization by spectroscopic Ellipsometry, the physical properties of silver nanoparticles.

    NASA Astrophysics Data System (ADS)

    Coanga, Jean-Maurice

    2013-04-01

    Physicists are able to change their minds through their experiments. I think it is time to go kick the curse and go further in research if we want a human future. I work in the Nano-Optics and Plasmonics research. I defined with ellipsomtrie the structure of new type of Nano particles of silver. It's same be act quickly to replace the old dirty leaded electronic-connexion chip and by the other hand to find a new way for the heath care of cancer disease by nanoparticles the next killers of bad cells. Silver nanoparticle layers are obtained by Spark Plasma Sintering are investigated as an alternative to lead alloy based material for solder joint in power mechatronics modules. These layers are characterized by mean of conventional techniques that is the dilatometry technique, the resistivity measurement through the van der Pauw method, and the flash laser technique. Furthermore, the nanoparticles of silver layer are deeply studied by UV-Visible spectroscopic ellipsometry. Spectroscopic angles parameters are determined in function of temperature and dielectric constants are deduced and analyzed through an optical model which takes into account a Drude and a Lorentz component within the Bruggeman effective medium approximation (EMA). The relaxation times and the electrical conductivity are plot in function of temperature. The obtained electrical conductivity give significant result in good agreement to those reported by four points electrical measurement method.

  14. Spectroscopic characterization of a contemporary Indian miniature painting.

    PubMed

    Cardeira, Ana Mafalda; Longelin, Stphane; Le Gac, Agns; Nogueira, Isabel; Carvalho, Maria Lusa; Manso, Marta

    2013-12-01

    A case study on a contemporary Indian miniature was carried out through the application of different spectroscopic techniques. Painting support, pigments, and dyes were largely characterized by means of energy dispersive x-ray fluorescence and Raman microspectroscopy directly on the artwork. Regarding golden motifs and silvered areas, for which these techniques have not provided enough information, scanning electron microscopy coupled with energy dispersive x-ray spectroscopy was used as a complementary technique. The painting support was identified as the Bombyx mori silk. Among the colorant matters, several pigments were identified such as chrome yellow, lithopone, hematite, lamp black, mica-titania pearlescent pigment, and tin-based metallic silver, and dyes such as phthalocyanine blue and the recent synthetic pigment red PR9 naphthol AS. All this materials will provide evidence in the support of the contemporary production of the artwork for future studies. PMID:24359650

  15. Synthesis and spectroscopic characterization of nanostructured anatase titania: A photocatalyst

    SciTech Connect

    Porkodi, K. . E-mail: porkodikathirvel@yahoo.com; Arokiamary, S. Daisy

    2007-06-15

    Nanocrystalline TiO{sub 2} was synthesized by the sol-gel process by controlling the crystallite size through calcination. The resulting nanocrystals were characterized using XRD, FT-Raman, SEM/EDX, DSC/TGA and UV-Vis spectroscopic techniques. XRD patterns confirmed the presence of only pure 100% anatase phase TiO{sub 2}. The surface morphology of the nanotitania was evaluated with Scanning Electron Microscopy. The purity of the sol-gel-derived TiO{sub 2} was confirmed through EDX measurements. The band gap of the nanotitania was found to be 3.6 eV from UV-Vis measurements. The pHzpc of the titania sample was measured as 5.90.

  16. Thermal, optical and spectroscopic characterizations of borate laser crystals

    SciTech Connect

    Chavoutier, M.; Jubera, V.; Veber, P.; Velazquez, M.; Viraphong, O.; Hejtmanek, J.; Decourt, R.; Debray, J.; Menaert, B.; Segonds, P.; Adamietz, F.; Rodriguez, V.; Manek-Hoenninger, I.; Fargues, A.; Descamps, D.; Garcia, A.

    2011-02-15

    The Yb-content Li{sub 6}Ln(BO{sub 3}){sub 3} (Ln: Gd, Y) solid solution has been investigated. Crystal growth has been successful for several compositions. A 22% molar content of ytterbium ions was determined by chemical analysis (ICP). Physical properties relevant to laser operation like mechanical hardness, thermal expansion and thermal conductivity were measured on single crystals. Optical measurements, including refractive index and low temperature spectroscopy, were also performed. Finally, the effect of the Y/Gd ratio is discussed. -- Graphical abstract: Several solid solutions of a rare earth borate were studied. The figure illustrates one of these single crystals obtained by Czochralski and shows thermal behaviour and absorption spectra at low temperature. Display Omitted Research highlights: {yields} We have grown by Czochralski method five Li{sub 6}Ln(BO{sub 3}){sub 3} (Ln=Y, Gd,Yb) single crystals. {yields} Chemical, physical and spectroscopic characteristics are reported. {yields} Data relevant to laser operation are listed.

  17. Near-infrared diode laser based spectroscopic detection of ammonia: a comparative study of photoacoustic and direct optical absorption methods

    NASA Technical Reports Server (NTRS)

    Bozoki, Zoltan; Mohacsi, Arpad; Szabo, Gabor; Bor, Zsolt; Erdelyi, Miklos; Chen, Weidong; Tittel, Frank K.

    2002-01-01

    A photoacoustic spectroscopic (PAS) and a direct optical absorption spectroscopic (OAS) gas sensor, both using continuous-wave room-temperature diode lasers operating at 1531.8 nm, were compared on the basis of ammonia detection. Excellent linear correlation between the detector signals of the two systems was found. Although the physical properties and the mode of operation of both sensors were significantly different, their performances were found to be remarkably similar, with a sub-ppm level minimum detectable concentration of ammonia and a fast response time in the range of a few minutes.

  18. Analyzing cell structure and dynamics with confocal light scattering and absorption spectroscopic microscopy

    NASA Astrophysics Data System (ADS)

    Qiu, Le; Vitkin, Edward; Fang, Hui; Zaman, Munir M.; Andersson, Charlotte; Salahuddin, Saira; Modell, Mark D.; Freedman, Steven D.; Hanlon, Eugene B.; Itzkan, Irving; Perelman, Lev T.

    2007-02-01

    We recently developed a new microscopic optical technique capable of noninvasive analysis of cell structure and cell dynamics on the submicron scale [1]. It combines confocal microscopy, a well-established high-resolution microscopic technique, with light scattering spectroscopy (LSS) and is called confocal light absorption and scattering spectroscopic (CLASS) microscopy. CLASS microscopy requires no exogenous labels and is capable of imaging and continuously monitoring individual viable cells, enabling the observation of cell and organelle functioning at scales on the order of 100 nm. To test the ability of CLASS microscopy to monitor cellular dynamics in vivo we performed experiments with human bronchial epithelial cells treated with DHA and undergoing apoptosis. The treated and untreated cells show not only clear differences in organelle spatial distribution but time sequencing experiments on a single cell show disappearance of certain types of organelles and change of the nuclear shape and density with the progression of apoptosis. In summary, CLASS microscopy provides an insight into metabolic processes within the cell and opens doors for the noninvasive real-time assessment of cellular dynamics. Noninvasive monitoring of cellular dynamics with CLASS microscopy can be used for a real-time dosimetry in a wide variety of medical and environmental applications that have no immediate observable outcome, such as photodynamic therapy, drug screening, and monitoring of toxins.

  19. Theory for the Spectroscopic Mode Frequencies and THz Absorption of Multiferroic BiFeO3

    NASA Astrophysics Data System (ADS)

    Fishman, Randy; Lee, Jun Hee

    2015-03-01

    A microscopic model for BiFeO3 that includes two Dzyaloshinskii-Moriya interactions and easy-axis anisotropy along the ferroelectric polarization predicts both the zero-field spectroscopic modes as well as their splitting and evolution in a magnetic field. Due to simultaneously broken time-reversal and spatial-inversion symmetries, the absorption of light changes slightly as the magnetic field or the direction of light propagation is reversed. We discuss three sets of physical mechanisms that contribute to the THz abosorption and directional dichroism (DD) of BiFeO3: spin current, magnetostriction, and anisotropy. First-principles calculations are used to obtain relationships among some of the polarization matrix elements induced by broken inversion symmetries in R3c structure. While our model nicely describes the DD along the magnetic field direction [1,-1,0], it fails to predict the weak DD observed for field along [1,1,0]. Research sponsored by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering.

  20. Confocal Light Absorption and Scattering Spectroscopic (CLASS) imaging: From cancer detection to sub-cellular function

    NASA Astrophysics Data System (ADS)

    Qiu, Le

    Light scattering spectroscopy (LSS), an optical technique that relates the spectroscopic properties of light elastically scattered by small particles to their size, refractive index and shape, has been recently successfully employed for sensing morphological and biochemical properties of epithelial tissues and cells in vivo. LSS does not require exogenous markers, is non-invasive, and, due to its multispectral nature, can sense biological structures well beyond the diffraction limit. All that makes LSS be a very good candidate to be used both in clinical medicine for in vivo detection of disease and in cell biology to monitor cell function on the organelle scale. Recently we developed two LSS-based imaging modalities: clinical Polarized LSS (PLSS) Endoscopic Technique for locating early pre-cancerous changes in GI tract and Confocal Light Absorption and Scattering Spectroscopic (CLASS) Microscopy for studying cells in vivo without exogenous markers. One important application of the clinical PLSS endoscopic instrument, a noncontact scanning imaging device compatible with the standard clinical endoscopes and capable of detecting dysplastic changes, is to serve as a guide for biopsy in Barrett's esophagus (BE). The instrument detects parallel and perpendicular components of the polarized light, backscattered from epithelial tissues, and determines characteristics of epithelial nuclei from the residual spectra. It also can find tissue oxygenation, hemoglobin content and other properties from the diffuse light component. By rapidly scanning esophagus the PLSS endoscopic instrument makes sure the entire BE portion is scanned and examined for the presence of dysplasia. CLASS microscopy, on the other hand, combines principles of light scattering spectroscopy (LSS) with confocal microscopy. Its main purpose is to image cells on organelle scale in vivo without the use of exogenous labels which may affect the cell function. The confocal geometry selects specific region and images are obtained by scanning the confocal volume across the sample. The new beam scanning CLASS microscope is a significant improvement over the previous proof-of-principle device. With this new device we have already performed experiments to monitor morphological changes in cells during apoptosis, differentiated fetal from maternal nucleated red blood cells, and detected plasmon scattering spectra of single gold nanorod.

  1. Spectroscopic detection, characterization and dynamics of free radicals relevant to combustion processes

    SciTech Connect

    Miller, Terry

    2015-06-04

    Combustion chemistry is enormously complex. The chemical mechanisms involve a multitude of elementary reaction steps and a comparable number of reactive intermediates, many of which are free radicals. Computer simulations based upon these mechanisms are limited by the validity of the mechanisms and the parameters characterizing the properties of the intermediates and their reactivity. Spectroscopy can provide data for sensitive and selective diagnostics to follow their reactions. Spectroscopic analysis also provides detailed parameters characterizing the properties of these intermediates. These parameters serve as experimental gold standards to benchmark predictions of these properties from large-scale, electronic structure calculations. This work has demonstrated the unique capabilities of near-infrared cavity ringdown spectroscopy (NIR CRDS) to identify, characterize and monitor intermediates of key importance in complex chemical reactions. Our studies have focussed on the large family of organic peroxy radicals which are arguably themost important intermediates in combustion chemistry and many other reactions involving the oxidation of organic compounds. Our spectroscopic studies have shown that the NIR Ã - ˜X electronic spectra of the peroxy radicals allows one to differentiate among chemical species in the organic peroxy family and also determine their isomeric and conformic structure in many cases. We have clearly demonstrated this capability on saturated and unsaturated peroxy radicals and β-hydroxy peroxy radicals. In addition we have developed a unique dual wavelength CRDS apparatus specifically for the purpose of measuring absolute absorption cross section and following the reaction of chemical intermediates. The utility of the apparatus has been demonstrated by measuring the cross-section and self-reaction rate constant for ethyl peroxy.

  2. Chromium(V) peptide complexes: synthesis and spectroscopic characterization.

    PubMed

    Barnard, Peter J; Levina, Aviva; Lay, Peter A

    2005-02-21

    A series of stable Cr(V) model complexes that mimic the binding of Cr(V) to peptide backbones at the C-terminus of proteins have been prepared for N,N-dimethylurea derivatives of the tripeptides Aib3-DMF, AibLAlaAib-DMF, and AibDAlaAib-DMF (Aib = 2-amino-2-methylpropanoic acid, DMF = N,N-dimethylformamide). The Cr(ll) precursor complexes were synthesized by the initial deprotonation of the amide and acid groups of the peptide ligands in DMF with potassium tert-butoxide in the presence of CrCl2. The Cr(II) intermediates thus formed were then immediately oxidized to Cr(V) using tert-butyl hydroperoxide. Spectroscopic and mass-spectrometric analyses of the Cr(V) complexes showed that a new metal-directed organic transformation of the ligand had occurred. This involved a DMF solvent molecule becoming covalently bound to the amine group of the peptide ligand, yielding a urea group, and a third coordinated deprotonated urea nitrogen donor. A metal-directed oxidative coupling has been proposed as a possible mechanism for the organic transformation. The Cr(V/IV) reduction potential was determined for the three Cr(V) complexes using cyclic voltammetry, and in all cases it was quasi-reversible. These are the first isolated and fully characterized Cr(V) complexes with non-sulfur-containing peptide ligands. PMID:15859285

  3. Spectroscopic characterization of collagen cross-links in bone

    NASA Technical Reports Server (NTRS)

    Paschalis, E. P.; Verdelis, K.; Doty, S. B.; Boskey, A. L.; Mendelsohn, R.; Yamauchi, M.

    2001-01-01

    Collagen is the most abundant protein of the organic matrix in mineralizing tissues. One of its most critical properties is its cross-linking pattern. The intermolecular cross-linking provides the fibrillar matrices with mechanical properties such as tensile strength and viscoelasticity. In this study, Fourier transform infrared (FTIR) spectroscopy and FTIR imaging (FTIRI) analyses were performed in a series of biochemically characterized samples including purified collagen cross-linked peptides, demineralized bovine bone collagen from animals of different ages, collagen from vitamin B6-deficient chick homogenized bone and their age- and sex-matched controls, and histologically stained thin sections from normal human iliac crest biopsy specimens. One region of the FTIR spectrum of particular interest (the amide I spectral region) was resolved into its underlying components. Of these components, the relative percent area ratio of two subbands at approximately 1660 cm(-1) and approximately 1690 cm(-1) was related to collagen cross-links that are abundant in mineralized tissues (i.e., pyridinoline [Pyr] and dehydrodihydroxylysinonorleucine [deH-DHLNL]). This study shows that it is feasible to monitor Pyr and DHLNL collagen cross-links spatial distribution in mineralized tissues. The spectroscopic parameter established in this study may be used in FTIRI analyses, thus enabling the calculation of relative Pyr/DHLNL amounts in thin (approximately 5 microm) calcified tissue sections with a spatial resolution of approximately 7 microm.

  4. Direct imaging and spectroscopic characterization of habitable planets with ELTs

    NASA Astrophysics Data System (ADS)

    Guyon, Olivier; Jovanovic, Nemanja; Lozi, Julien

    2015-12-01

    While the ~1e10 reflected light contrast between Earth-like planets and Sun-like stars is extremely challenging to overcome for ground-based telescopes, habitable planets around lower-mass stars can be "only" a 10 million times fainter than their host stars. Thanks to the small angular resolution offered by upcoming extremely large telescopes (ELTs) and recent advances in wavefront control and coronagraphic techniques, direct imaging and spectroscopic characterization of habitable planets will be possible around nearby M-type stars. Deep (~1e-8) contrast can be achieved by combining (1) sensitive fast visible light wavefront sensing (extreme-AO) with (2) kHz speckle control in the near-IR and (3) high efficiency coronagraphy. Spectroscopy will measure abundances of water, oxygen and methane, measure the planet rotation period, orbit, and identify main surface features through time-domain spectrophotometry.The Subaru Coronagraphic Extreme AO (SCExAO) system is a technology precursor to such a habitable planet imager for ELTs, and is currently under active development. By combining small inner working angle coronagraphy, visible-WFS based extreme-AO and fast speckle control, it will include the key elements of a future ELT system able to image and characterize habitable planets. We describe a technical plan to evolve SCExAO into a habitable planet imager for the Thirty Meter Telescope (TMT), which is aimed at providing such scientific capability during the 2020 decade, and inform the design, deployment and scientific operation of a more capable Extreme-AO instrument.

  5. Synthesis, spectroscopic characterization and comparative DNA binding studies of Schiff base complexes derived from L-leucine and glyoxal.

    PubMed

    Shakir, Mohammad; Shahid, Nida; Sami, Naushaba; Azam, Mohammad; Khan, Asad U

    2011-11-01

    The mononuclear Schiff base complexes of the type, [ML(CH(3)OH)(2)] [M = Co(II), Ni(II), Cu(II) and Zn(II)] have been synthesized by template condensation of L-leucine and glyoxal. The complexes have been characterized on the basis of the results of the elemental analysis, molar conductance, magnetic susceptibility measurements and spectroscopic studies viz, FT-IR, Mass, (1)H NMR and (13)C NMR spectra. The UV-vis and magnetic moment data revealed an octahedral geometry around Co(II), Ni(II) ion with distortion around Cu(II) ion complex confirmed by EPR data. The conductivity data show a non-electrolytic nature of the complexes. Absorption and fluorescence spectroscopic studies support that all the complexes exhibit a significant binding to calf thymus DNA. PMID:21807556

  6. Spectroscopic characterizations of the mixed Langmuir-Blodgett (LB) films of 2,2'-biquinoline molecules: Evidence of dimer formation

    NASA Astrophysics Data System (ADS)

    Deb, S.; Biswas, S.; Hussain, S. A.; Bhattacharjee, D.

    2005-04-01

    This communication reports the ?- A isotherms and spectroscopic characterizations of mixed Langmuir and Langmuir-Blodgett (LB) films of non-amphiphilic 2,2'-biquinoline (BQ) molecules, mixed with polymethyl methacrylate (PMMA) and stearic acid (SA). The ?- A isotherms and mole fraction vs. area per molecule studies indicate complete immiscibility of sample (BQ) and matrix (PMMA or SA) molecules. This immiscibility may lead to the formation of microcrystalline aggregates of BQ molecules in the mixed LB films. The scanning electron micrograph gives the visual evidence of microcrystalline aggregates of BQ molecules in the mixed LB films. UV-vis absorption, fluorescence and excitation spectroscopic studies reveal the nature of these microcrystalline aggregates. LB films lifted at higher surface pressure indicate the formation of dimer or higher order n-mers.

  7. Transient absorption characterization of Cu- and Zn-metallized derivatives of meso-tetrakis(4-caynophenyl) N-confused porphyrin

    NASA Astrophysics Data System (ADS)

    Ao, Guanghong; Xiao, Zhengguo; Wang, Yuxiao; Zhang, Xueru; Song, Yinglin

    2015-10-01

    Meso-tetrakis(4-cyanophenyl)N-confused porphyrin [NCTPP(CN)4] and its two metallized derivatives with Cu2+ and Zn2+ ligand in the central position of the macrocycle are synthesized and spectroscopically characterized. Their excited-state dynamics are investigated with transient absorption (TA) spectroscopy upon excitation by 190 fs laser pulses at 420 nm within their Soret band region. A global and target analysis for the TA spectra of each porphyrin is performed via a four-level model including singlet (S) and triplet (T) states to extract the photophysical parameters at a variety of absorption wavelengths. Furthermore the corresponding excited-state lifetimes are extracted and discussed.

  8. Theoretical modeling of the spectroscopic absorption properties of luciferin and oxyluciferin: A critical comparison with recent experimental studies

    NASA Astrophysics Data System (ADS)

    Anselmi, Massimiliano; Marocchi, Simone; Aschi, Massimiliano; Amadei, Andrea

    2012-01-01

    Firefly luciferin and its oxidated form, oxyluciferin, are two heterocyclic compounds involved in the enzymatic reaction, catalyzed by redox proteins called luciferases, which provides the bioluminescence in a wide group of arthropods. Whereas the electronic absorption spectra of D-luciferin in water at different pHs are known since 1960s, only recently reliable experimental electronic spectra of oxyluciferin have become available. In addition oxyluciferin is involved in a triple chemical equilibria (deprotonation of the two hydroxyl groups and keto-enol tautomerism of the 4-hydroxythiazole ring), that obligates to select during an experiment a predominant species, tuning pH or solvent polarity besides introducing chemical modifications. In this study we report the absorption spectra of luciferin and oxyluciferin in each principal chemical form, calculated by means of perturbed matrix method (PMM), which allowed us to successfully introduce the effect of the solvent on the spectroscopic absorption properties, and compare the result with available experimental data.

  9. PROCESSING OF HIGH LEVEL WASTE: SPECTROSCOPIC CHARACTERIZATION OF REDOX REACTIONS IN SUPERCRITICAL WATER

    EPA Science Inventory

    Current efforts are focused on the oxidative dissolution of chromium compounds found in Hanford tank waste sludge. Samples of chromium oxides and hydroxides with varying degrees of hydration are being characterized using Raman, FTIR, and XPS spectroscopic techniques. Kinetics of ...

  10. Structural and spectroscopic characterization of mixed planetary ices.

    PubMed

    Plattner, Nuria; Lee, Myung Won; Meuwly, Markus

    2010-01-01

    Mixed ices play a central role in characterizing the origin, evolution, stability and chemistry of planetary ice surfaces. Examples include the polar areas of Mars, the crust of the Jupiter moon Europa, or atmospheres of planets and their satellites, particularly in the outer solar system. Atomistic simulations using accurate representations of the interaction potentials have recently shown to be suitable to quantitatively describe both, the mid- and the far-infrared spectrum of mixed H2O/CO amorphous ices. In this work, molecular dynamics simulations are used to investigate structural and spectroscopic properties of mixed and crystalline ices containing H2O, CO and CO2. Particular findings include: (a) the sensitivity of the water bending mode to the local environment of the water molecules which, together with structural insights from MD simulations, provides a detailed picture for the relationship between spectroscopy and structure; and (b) the sensitivity of the low-frequency spectrum to the structure of the mixed CO2/H2O ice. Specifically, for mixed H2O/CO2 ices with low water contents isolated water molecules are found which give rise to a band shifted by only 12 cm(-1) from the gas-phase value whereas for increasing water concentration (for a 1 : 1 mixture) the band progressively shifts to higher frequency because water clusters can form. More generally it is found that changes in the ice structure due to the presence of CO2 are larger compared to changes induced by the presence of CO and that this difference is reflected in the shape of the water bending vibration. Thus, the water bending vibration appears to be a suitable diagnostic for structural and chemical aspects of mixed ices. PMID:21302549

  11. Functional and Spectroscopic Characterization of Chlamydomonas reinhardtii Truncated Hemoglobins

    PubMed Central

    Droghetti, Enrica; Tundo, Grazia R.; Sanz-Luque, Emanuel; Polticelli, Fabio; Visca, Paolo; Smulevich, Giulietta; Ascenzi, Paolo; Coletta, Massimo

    2015-01-01

    The single-cell green alga Chlamydomonas reinhardtii harbors twelve truncated hemoglobins (Cr-TrHbs). Cr-TrHb1-1 and Cr-TrHb1-8 have been postulated to be parts of the nitrogen assimilation pathway, and of a NO-dependent signaling pathway, respectively. Here, spectroscopic and reactivity properties of Cr-TrHb1-1, Cr-TrHb1-2, and Cr-TrHb1-4, all belonging to clsss 1 (previously known as group N or group I), are reported. The ferric form of Cr-TrHb1-1, Cr-TrHb1-2, and Cr-TrHb1-4 displays a stable 6cLS heme-Fe atom, whereas the hexa-coordination of the ferrous derivative appears less strongly stabilized. Accordingly, kinetics of azide binding to ferric Cr-TrHb1-1, Cr-TrHb1-2, and Cr-TrHb1-4 are independent of the ligand concentration. Conversely, kinetics of CO or NO2? binding to ferrous Cr-TrHb1-1, Cr-TrHb1-2, and Cr-TrHb1-4 are ligand-dependent at low CO or NO2? concentrations, tending to level off at high ligand concentrations, suggesting the presence of a rate-limiting step. In agreement with the different heme-Fe environments, the pH-dependent kinetics for CO and NO2?binding to ferrous Cr-TrHb1-1, Cr-TrHb1-2, and Cr-TrHb1-4 are characterized by different ligand-linked protonation events. This raises the question of whether the simultaneous presence in C. reinhardtii of multiple TrHb1s may be related to different regulatory roles. PMID:25993270

  12. Mid-infrared vibrational spectroscopic characterization of 5,6-dihydroxyindole and eumelanin derived from it

    NASA Astrophysics Data System (ADS)

    Hyogo, Ryosuke; Nakamura, Atsushi; Okuda, Hidekazu; Wakamatsu, Kazumasa; Ito, Shosuke; Sota, Takayuki

    2011-12-01

    Mid-infrared vibrational spectroscopic study has been made on 5,6-dihydroxyindole (DHI) and DHI-derived eumelanin. It has been revealed for DHI monomer that measured infrared absorption spectrum is well reproduced by that predicted from ab initio calculations. Thus, vibrational modes of DHI monomer causing dominant absorption bands have been successfully assigned. It has been also reconfirmed that DHI-derived eumelanin includes indolequinone and/or quinone methide units in addition to DHI units.

  13. Absorption properties of type-II InAs/InAsSb superlattices measured by spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Webster, P. T.; Riordan, N. A.; Liu, S.; Steenbergen, E. H.; Synowicki, R. A.; Zhang, Y.-H.; Johnson, S. R.

    2015-02-01

    Strain-balanced InAs/InAsSb superlattices offer access to the mid- to long-wavelength infrared region with what is essentially a ternary material system at the GaSb lattice constant. The absorption coefficients of InAs/InAsSb superlattices grown by molecular beam epitaxy on (100)-oriented GaSb substrates are measured at room temperature over the 30 to 800 meV photon energy range using spectroscopic ellipsometry, and the miniband structure of each superlattice is calculated using a Kronig-Penney model. The InAs/InAsSb conduction band offset is used as a fitting parameter to align the calculated superlattice ground state transition energy to the measured absorption onset at room temperature and to the photoluminescence peak energy at low temperature. It is observed that the ground state absorption coefficient and transition strength are proportional to the square of the wavefunction overlap and the ground state absorption coefficient approaches a maximum value of around 5780 cm-1 as the wavefunction overlap approaches 100%. The absorption analysis of these samples indicates that the optical joint density of states is weakly dependent on the period thickness and Sb content of the superlattice, and that wavefunction overlap is the principal design parameter in terms of obtaining strong absorption in these structures.

  14. Absorption properties of type-II InAs/InAsSb superlattices measured by spectroscopic ellipsometry

    SciTech Connect

    Webster, P. T.; Riordan, N. A.; Liu, S.; Zhang, Y.-H.; Johnson, S. R.; Steenbergen, E. H.

    2015-02-09

    Strain-balanced InAs/InAsSb superlattices offer access to the mid- to long-wavelength infrared region with what is essentially a ternary material system at the GaSb lattice constant. The absorption coefficients of InAs/InAsSb superlattices grown by molecular beam epitaxy on (100)-oriented GaSb substrates are measured at room temperature over the 30 to 800 meV photon energy range using spectroscopic ellipsometry, and the miniband structure of each superlattice is calculated using a Kronig-Penney model. The InAs/InAsSb conduction band offset is used as a fitting parameter to align the calculated superlattice ground state transition energy to the measured absorption onset at room temperature and to the photoluminescence peak energy at low temperature. It is observed that the ground state absorption coefficient and transition strength are proportional to the square of the wavefunction overlap and the ground state absorption coefficient approaches a maximum value of around 5780 cm{sup −1} as the wavefunction overlap approaches 100%. The absorption analysis of these samples indicates that the optical joint density of states is weakly dependent on the period thickness and Sb content of the superlattice, and that wavefunction overlap is the principal design parameter in terms of obtaining strong absorption in these structures.

  15. Structural and spectroscopic characterization of plutonyl(VI) nitrate under acidic conditions.

    PubMed

    Gaunt, Andrew J; May, Iain; Neu, Mary P; Reilly, Sean D; Scott, Brian L

    2011-05-16

    The plutonyl(VI) dinitrate complex [PuO(2)(NO(3))(2)(H(2)O)(2)]H(2)O (1) has been structurally characterized by single-crystal X-ray diffraction and spectroscopically characterized by solid-state vis-NIR and Raman spectroscopies. Aqueous solution spectroscopic studies indicate only weak plutonyl(VI) nitrate complexation, with the mononitrate complex dominating and negligible dinitrate formation, even in concentrated nitric acid. PMID:21510662

  16. Possibilities and limitations of imaging spectroscopic reflectometry in optical characterization of thin films

    NASA Astrophysics Data System (ADS)

    Ohlídal, Miloslav; Ohlidal, Ivan; Nečas, David; Vodák, Jiří; Franta, Daniel; Nádaský, Pavel; Vižd'a, František

    2015-09-01

    It is possible to encounter thin films exhibiting various defects in practice. One of these defects is area non-uniformity in optical parameters (e.g. in thickness). Therefore it is necessary to have methods for an optical characterization of nonuniform thin films. Imaging spectroscopic reflectometry provides methods enabling us to perform an efficient optical characterization of such films. It gives a possibility to determine spectral dependencies of a local reflectance at normal incidence of light belonging to small areas (37 μm × 37 μm in our case) on these non-uniform films. The local reflectance is measured by individual pixels of a CCD camera serving as a detector of an imaging spectroscopic reflectometer. It is mostly possible to express the local reflectance using formulas corresponding to a uniform thin film. It allows a relatively simple treatment of the experimental data obtained by imaging spectroscopic reflectometry. There are three methods for treating these experimental data in the special case of thickness non-uniformity, i.e. in the case of the same optical constants within a certain area of the film - single pixel imaging spectroscopic reflectometry method, combination of single-pixel imaging spectroscopic reflectometry method and conventional methods (conventional single spot spectroscopic ellipsometry and spectrophotometry), and multi-pixel imaging spectroscopic reflectometry method. These methods are discussed and examples of the optical characterization of thin films non-uniform in thickness corresponding to these methods are presented in this contribution.

  17. White-light continuum probed femtosecond time-resolved absorption spectroscopic measurement of β-carotene under high pressure

    NASA Astrophysics Data System (ADS)

    Liu, Wei-Long; Zheng, Zhi-Ren; Zhang, Jian-Ping; Wu, Wen-Zhi; Li, Ai-Hua; Zhang, Wei; Huo, Ming-Ming; Liu, Zhi-Guo; Zhu, Rui-Bin; Zhao, Lian-Cheng; Su, Wen-Hui

    2012-04-01

    We have performed a femtosecond time-resolved absorption spectroscopic experiment of β-carotene in n-hexane solution under high pressure up to ˜1.0 GPa. Using white-light continuum in the visible spectral region as probe light, we found that the energy level of S1 state descends, whereas its lifetime becomes longer with the rising pressure. We ascribe this tendency deviating from the energy gap law to the viscosity effects on the Cdbnd C stretching vibrations, which is fully consistent with the microviscosity theory. This Letter may provide some insights on the light harvesting and photoprotection functions of carotenoids in photosynthetic organisms.

  18. Spectroscopic characterization of iron-doped II-VI compounds for laser applications

    NASA Astrophysics Data System (ADS)

    Martinez, Alan

    The middle Infrared (mid-IR) region of the electromagnetic spectrum between 2 and 15 ?m has many features which are of interest to a variety of fields such as molecular spectroscopy, biomedical applications, industrial process control, oil prospecting, free-space communication and defense-related applications. Because of this, there is a demand for broadly tunable, laser sources operating over this spectral region which can be easily and inexpensively produced. II-VI semiconductor materials doped with transition metals (TM) such as Co 2+, Cr2+, or Fe2+ exhibit highly favorable spectroscopic characteristics for mid-IR laser applications. Among these TM dopants, Fe2+ has absorption and emission which extend the farthest into the longer wavelength portion of the mid-IR. Fe2+:II-VI crystals have been utilized as gain elements in laser systems broadly tunable over the 3-5.5 microm range [1] and as saturable absorbers to Q -switch [2] and mode-lock [3] laser cavities operating over the 2.7-3 microm. TM:II-VI laser gain elements can be fabricated inexpensively by means of post-growth thermal diffusion with large homogeneous dopant concentration and good optical quality[4,5]. The work outlined in this dissertation will focus on the spectroscopic characterization of TM-doped II-VI semiconductors. This work can be categorized into three major thrusts: 1) the development of novel laser materials, 2) improving and extending applications of TM:II-VI crystals as saturable absorbers, and 3) fabrication of laser active bulk crystals. Because current laser sources based on TM:II-VI materials do not cover the entire mid-IR spectral region, it is necessary to explore novel laser sources to extend available emissions toward longer wavelengths. The first objective of this dissertation is the spectroscopic characterization of novel ternary host crystals doped with Fe2+ ions. Using crystal field engineering, laser materials can be prepared with emissions placed in spectral regions not currently covered by available sources while maintaining absorption which overlaps with available pump sources. Because optimization of these materials requires extensive experimentation, a technique to fabricate and characterize novel crystals in powder form was developed, eliminating the need for the crystal growth. Powders were characterized using Raman, photoluminescence studies, and kinetics of luminescence. The first demonstration of random lasing of Fe:ZnCdTe powder at 6 microm was reported. These results show promise for the development of these TM-doped ternary II-VI compounds as laser gain media operating at 6 microm and longer. The second major objective was to study the performance of TM:II-VI elements as saturable absorber Q-switches and mode-lockers in flash lamp pumped Er:YAG and Er:Cr:YSGG cavities. Different cavity schemes were arranged to eliminate depolarization losses and improve Q-switching performance in Er:YAG and the first use of Cr:ZnSe to passively Q -switch an Er:Cr:YSGG cavity was demonstrated. While post-growth thermal diffusion is an effective way to prepare large-scale highly doped TM:II-VI laser elements, the diffusion rate of some ions into II-VI semiconductors is too low to make this method practical for large crystals. The third objective was to improve the rate of thermal diffusion of iron into II-VI semiconductor crystals by means of gamma-irradiation during the diffusion process. When exposed to a dose rate of 44 R/s during the diffusion process, the diffusion coefficient for Fe into ZnSe showed improvement of 60% and the diffusion coefficient of Fe into ZnS showed improvement of 30%.

  19. Nanofluid optical property characterization: towards efficient direct absorption solar collectors

    PubMed Central

    2011-01-01

    Suspensions of nanoparticles (i.e., particles with diameters < 100 nm) in liquids, termed nanofluids, show remarkable thermal and optical property changes from the base liquid at low particle loadings. Recent studies also indicate that selected nanofluids may improve the efficiency of direct absorption solar thermal collectors. To determine the effectiveness of nanofluids in solar applications, their ability to convert light energy to thermal energy must be known. That is, their absorption of the solar spectrum must be established. Accordingly, this study compares model predictions to spectroscopic measurements of extinction coefficients over wavelengths that are important for solar energy (0.25 to 2.5 ?m). A simple addition of the base fluid and nanoparticle extinction coefficients is applied as an approximation of the effective nanofluid extinction coefficient. Comparisons with measured extinction coefficients reveal that the approximation works well with water-based nanofluids containing graphite nanoparticles but less well with metallic nanoparticles and/or oil-based fluids. For the materials used in this study, over 95% of incoming sunlight can be absorbed (in a nanofluid thickness ?10 cm) with extremely low nanoparticle volume fractions - less than 1 10-5, or 10 parts per million. Thus, nanofluids could be used to absorb sunlight with a negligible amount of viscosity and/or density (read: pumping power) increase. PMID:21711750

  20. Synthesis and spectroscopic characterization of a new (aryl-SCN)n polymer: Polythiocyanatohydroquinone

    NASA Astrophysics Data System (ADS)

    Baryshnikov, Gleb V.; Galagan, Rostislav L.; Shepetun, Ludmila P.; Litvin, Valentina A.; Minaev, Boris F.

    2015-09-01

    In the present work we have demonstrated the first synthesis of the polythiocyanogen-like (aryl-SCN)n compound (polythiocyanatohydroquinone) from the initial 1,4-benzoquinone and NH4SCN reagents under the normal conditions in the glacial acetic acid medium. The synthesized amorphous polymer was characterized experimentally by the FT-IR and UV-vis spectroscopic methods accompanied with theoretical assignments by the density functional theory (DFT) and time-dependent DFT calculations. The transmission electron microscopy and the XRD pattern analysis were used to indicate the amorphous structure of the synthesized polymer. The DFT geometry optimization of a number of oligomers (n = 4-8) permit us to predict the possible structure of polythiocyanatohydroquinone and to assign the observed bands in IR and UV-vis absorption spectra. It was found that the synthesized polythiocyanatohydroquinone powder has a complicated structure which can be represented as a branched polymer constructed from the mono- and doubly-SCN-substituted benzene-1,4-diol moieties. This new material demonstrates a good stabilizing effect in respect to colloidal solutions of Ag and Au nanoparticles. Additionally, polythiocyanatohydroquinone is predicted to be a promising candidate for creation of metal-containing composite materials. Its application as a framework for the Pt electrode closing is found very useful.

  1. Spectroscopic characterization of novel multilayer mirrors intended for astronomical and laboratory applications

    NASA Astrophysics Data System (ADS)

    Ragozin, Eugene N.; Mednikov, Konstantin N.; Pertsov, Andrei A.; Pirozhkov, Alexander S.; Reva, Anton A.; Shestov, Sergei V.; Ul'yanov, Artem S.; Vishnyakov, Eugene A.

    2009-05-01

    We report measurements of the reflection spectra of (i) concave (spherical and parabolic) Mo/Si, Mg/Si, and Al/Zr multilayer mirrors (MMs) intended for imaging solar spectroscopy in the framework of the TESIS/CORONAS-FOTON Satellite Project and of (ii) an aperiodic Mo/Si MM optimized for maximum uniform reflectivity in the 125-250 range intended for laboratory applications. The reflection spectra were measured in the configuration of a transmission grating spectrometer employing the radiation of a tungsten laser-driven plasma as the source. The function of detectors was fulfilled by backside-illuminated CCDs coated with Al or Zr/Si multilayer absorption filters. High-intensity second-order interference reflection peaks at wavelengths of about 160 were revealed in the reflection spectra of the 304- Mo/Si MMs. By contrast, the second-order reflection peak in the spectra of the new-generation narrow-band (~12 FWHM) 304- Mg/Si MMs is substantially depressed. Manifestations of the NEXAFS structure of the L2, 3 absorption edges of Al and Al2O3 were observed in the spectra recorded. The broadband Mo/Si MM was employed as the focusing element of spectrometers in experiments involving (i) the charge exchange of multiply charged ions with the donor atoms of a rare-gas jet; (ii) the spectroscopic characterization of a debris-free soft X-ray radiation source excited by Nd laser pulses in a Xe jet (iii) near-IR-to-soft-X-ray frequency conversion (double Doppler effect) occurring in the retroreflection from the relativistic electron plasma wake wave (flying mirror) driven by a multiterawatt laser in a pulsed helium jet.

  2. Spectroscopic characterizations of rare earth doped ceramics, nanocrystals, nanocrystal embedded polymeric hosts and their potential applications

    NASA Astrophysics Data System (ADS)

    Nash, Kelly Latrice

    Trivalent rare earth (RE3+) ions have been used as an activator in laser host materials and in a wide variety of photonic applications. Of the competing hosts, one of the most well studied and successful host has been yttrium aluminum garnet Y3Al5O12 (YAG). In comparison to YAG, yttrium oxide (Y2O3) has shown promise as a potential laser medium due to its excellent optical, thermal and mechanical properties. As single crystals, Y2O3 system can be extremely difficult to grow due to the high melting temperature (2200C) of the host. Alternatively, ceramic and nanocrystalline forms of Y2O3 have contributed to renewed interest in the material as laser host and more recently in biological and other photonic applications due to simplicity of fabrication. This work focuses on four RE 3+ ions, namely erbium, neodymium, holmium, europium doped into Y 2O3 and are selected due to their multi-frequency absorption properties and visible to near infrared emission characteristics. The chosen nanocrystalline material are embedded or coated in polymers that are biocompatible resulting in visible to near infrared fluorescent polymers. These materials are characterized through morphology studies and spectroscopic analyses of the absorption and emission spectra. Judd-Ofelt (J-O) and Crystal-Field (CF) techniques are applied to the systems and the results are compared to single crystal and ceramic forms and in some cases these analyses are reported for the first time for this host. Results of these analyses show that the addition of near infrared emitting rare earth nanocrystals to these polymers offers an attractive application to their existing biological applications.

  3. Raman spectroscopic characterization and differentiation of seminal plasma

    NASA Astrophysics Data System (ADS)

    Huang, Zufang; Chen, Xiwen; Chen, Yanping; Chen, Jinhua; Dou, Min; Feng, Shangyuan; Zeng, Haishan; Chen, Rong

    2011-11-01

    Raman spectroscopy (RS) was applied for the analysis of seminal plasma in order to detect spectral parameters, which might be used for differentiating the normal and abnormal semen samples. Raman spectra of seminal plasma separated from normal and abnormal semen samples, showed a distinct difference in peak ratios between 1449 and 1418 cm-1 (P < 0.05). More efficient alternative method of using principal component analysis-linear discriminate analysis based on Raman spectroscopic data yielded a diagnostic sensitivity of 73% and specificity of 82%. The results suggest that RS combined with the multivariate analysis method has the potential for differentiating semen samples by examination of the corresponding seminal plasma.

  4. Life Finder Detectors; Detector Needs and Status for Spectroscopic Biosignature Characterization

    NASA Astrophysics Data System (ADS)

    Rauscher, Bernard J.; Bolcar, Matthew R.; Clampin, Mark; Domagal-Goldman, Shawn; McElwain, Michael W.; Moseley, Samuel H.; Stahle, Carl; Stark, Christopher C.; Thronson, Harley A.

    2016-01-01

    The search for life on other worlds looms large in NASA's future. Outside our solar system, direct spectroscopic biosignature characterization using very large UV-Optical-IR telescopes with coronagraphs or starshades is a core technique to both AURA's High Definition Space Telescope (HDST) concept and NASA's 30-year strategic plan. These giant space observatories require technological advancements in several areas, one of which is detectors. In this presentation, we review the detector requirements for spectroscopic biosignature characterization and discuss the status of some existing and proposed detector technologies for meeting them.

  5. Optical absorption spectroscopic diagnostics during sputter deposition of Y-Ba-Cu-oxide

    NASA Astrophysics Data System (ADS)

    Blair, A. J.; Metzger, G.; Fleddermann, C. B.

    1992-11-01

    Optical absorption spectroscopy has been used in situ as a diagnostic for studying the sputter deposition of high-temperature superconductors. Both atomic and molecular species were monitored using hollow-cathode lamps as line sources and a quartz tungsten-halogen lamp as a broadband source. Measurements were made of the relative atomic and molecular species concentrations in front of the target during sputtering of Y-Ba-Cu-oxide targets using a Kaufman ion gun. The absorption measurements showed that the fluxes of ground state Ba, Cu, BaO, and CuO ejected from a composite target during argon- and oxygen-ion bombardment varied greatly with sputtering parameters. Absorptions due to Y and YO were too weak to be reliably measured. Various studies of the effects of changes in ion-beam energy, ion flux to the target, target temperature, oxygen content of the beam, and incident ion angle were performed. Stoichiometry of deposited films was also measured and correlated to the absorption results. Absorption measurements during argon- and oxygen-ion sputtering of a pure copper target were made for comparison with the results from the superconducting target. These measurements show that the relative density of species ejected from the target is highly dependent on the sputtering conditions, and indicate that careful control of beam parameters is essential for repeatable stoichiometry in deposited films.

  6. Comprehensive Spectroscopic Characterization of Model Aromatic Substituents of Lignin

    NASA Astrophysics Data System (ADS)

    Dean, Jacob C.; Vara, Vanesa Vaquero; Hotopp, Kelly M.; Dian, Brian C.; Zwier, Timothy S.

    2012-06-01

    2,6-Dimethoxyphenol (2,6-DMP) is a model compound with aromatic substitution similar to that in sinapyl alcohol, one of the three monomers that make up lignin. 2,6-DMP has been studied combining several spectroscopic techniques that span the microwave, infrared and ultraviolet regions. Spectra from laser-induced fluorescence excitation, IR-UV hole-burning, fluorescence dip IR, dispersed fluorescence and rotational spectra have allowed us to develop more insight to the structural details, intramolecular H-bonding and electronic excited states of this sinapyl alcohol analog. Coupling in the CH stretch region, broadening effects in the IR spectra and Coriolis coupling due to the OH tunneling coordinate in the rotational spectrum will be shown as we present this diverse set of experimental data involving transitions between different vibronic, vibrational and rotational levels of the molecule. These features will be compared to those in 2-methoxyphenol and 4-methyl-2,6-DMP during the discussion.

  7. SPECTROSCOPIC CHARACTERIZATION AND DETECTION OF ETHYL MERCAPTAN IN ORION

    SciTech Connect

    Kolesniková, L.; Alonso, J. L.; Daly, A. M.; Tercero, B.; Cernicharo, J.; Gordon, B. P.; Shipman, S. T. E-mail: jlalonso@qf.uva.es E-mail: terceromb@cab.inta-csic.es E-mail: brittany.gordon@ncf.edu

    2014-03-20

    New laboratory data of ethyl mercaptan, CH{sub 3}CH{sub 2}SH, in the millimeter- and submillimeter-wave domains (up to 880 GHz) provided very precise values of the spectroscopic constants that allowed the detection of gauche-CH{sub 3}CH{sub 2}SH toward Orion KL. This identification is supported by 77 unblended or slightly blended lines plus no missing transitions in the range 80-280 GHz. A detection of methyl mercaptan, CH{sub 3}SH, in the spectral survey of Orion KL is reported as well. Our column density results indicate that methyl mercaptan is ≅ 5 times more abundant than ethyl mercaptan in the hot core of Orion KL.

  8. Combined interferometric and absorption-spectroscopic technique for determining molecular line strengths: Applications to CO{sub 2}

    SciTech Connect

    Castrillo, A.; Gagliardi, G.; Casa, G.; Gianfrani, L.

    2003-06-01

    A diode-laser-based technique has been developed for absolute line strength measurements with high precision and accuracy, combining a spectroscopic determination of the integrated absorbance with an optical measurement of the absorption path length by means of a Michelson interferometer. This method has been applied to several {sup 12}C{sup 16}O{sub 2} vibrorotational transitions belonging to the {nu}{sub 1}+2{nu}{sub 2}{sup 0}+{nu}{sub 3} combination band, in the spectral region around 2 {mu}m. The 1{sigma} overall accuracy in line strength determination ranges between 0.4% and 0.7%, while the experimental reproducibility is estimated to be around 0.1%. To our knowledge, these levels are the highest ever reached before. The pressure-broadening coefficients for the same transitions are also reported.

  9. Characterization of used mineral oil condition by spectroscopic techniques.

    PubMed

    Vanhanen, Jarmo; Rinkiö, Marcus; Aumanen, Jukka; Korppi-Tommola, Jouko; Kolehmainen, Erkki; Kerkkänen, Tuula; Törmä, Päivi

    2004-08-20

    Optical absorption, fluorescence, and quantitative 13C NMR spectroscopy have been used to study the degradation of mineral gearbox oil. Samples of used oil were collected from field service. Measured absorption, fluorescence, and quantitative 13C NMR spectra of used oils show characteristic changes from the spectra of a fresh oil sample. A clearly observable, approximately 20-nm blueshift of the fluorescence emission occurs during the early stages of oil use and correlates with changes in intensity of some specific 13C NMR resonance lines. These changes correlate with oil age because of the connection between the blueshift and breaking of the larger conjugated hydrocarbons of oil as a result of use. PMID:15352397

  10. Spectroscopic modeling and characterization of a collisionally confined laser-ablated plasma plume.

    PubMed

    Sherrill, M E; Mancini, R C; Bailey, J; Filuk, A; Clark, B; Lake, P; Abdallah, J

    2007-11-01

    Plasma plumes produced by laser ablation are an established method for manufacturing the high quality stoichiometrically complex thin films used for a variety of optical, photoelectric, and superconducting applications. The state and reproducibility of the plasma close to the surface of the irradiated target plays a critical role in producing high quality thin films. Unfortunately, this dense plasma has historically eluded quantifiable characterization. The difficulty in modeling the plume formation arises in the accounting for the small amount of energy deposited into the target when physical properties of these exotic target materials are not known. In this work we obtain the high density state of the plasma plume through the use of an experimental spectroscopic technique and a custom spectroscopic model. In addition to obtaining detailed temperature and density profiles, issues regarding line broadening and opacity for spectroscopic characterization will be addressed for this unique environment. PMID:18233770

  11. Synthesis and spectroscopic characterization of nanostructured thermoelectric materials

    NASA Astrophysics Data System (ADS)

    Reppert, Jason Brooks

    Bismuth in the bulk form is a semimetal with a rhombohedral structure. It has a small band overlap between the conduction and valence bands and a highly anisotropic electron effective-mass tensor. Thermoelectric materials, in which one of the three dimensions is in the nanometer regime, exhibit unique quantum confinement properties and have generated much interest in recent years. Theoretical investigations have suggested that nanowires with diameters ≤ 10 nm will possess a figure-of-merit ZT > 2. Prior to this study, it has been shown that Bi nanowires with small enough diameters (˜10 nm), prepared via the pulsed laser vaporization method, undergo a transition from a semimetal with a small band overlap to a semiconductor with a small indirect band gap. Infrared absorption and UV-visible measurements were used to confirm this semimetal-to-semiconductor phase transition. In this thesis, we report the synthesis and optical characteristics of a variety of various potential thermoelectric materials including bismuth, nickel sulfide and cadmium sulfide. The infrared absorption in our Bi nanorods is blue-shifted in energy when compared to the corresponding spectra in bulk Bi, and when cooled down to liquid nitrogen temperatures, group theory suggests a strong temperature dependence in the Bi band structure. We also find that the Bi nanorod suspension displays excellent optical limiting properties at both 532 and 1064 nm excitations in the nanosecond laser pulse regime. We have also synthesized nickel sulfide nanoparticles with an average size of 5 nm by a one-step solid phase reaction. The intensity-dependent nonlinear transmission study was carried out using a 7 ns Nd:YAG laser at 532nm using Z-scan, and the nonlinear scattering was found to be the dominant mechanism for the observed response. Importantly, the modified Z-scan method allowed us to measure two competing mechanisms simultaneously - the optical limiting and saturable absorption in surface-modified nickel sulfide nanoparticles suspensions.

  12. Electronic absorption spectroscopic behavior and acidity constants of some new dinitrophenylhydrazone derivatives

    NASA Astrophysics Data System (ADS)

    Alizadeh, Kamal; Amraie, Abouzar

    2015-08-01

    In the present study, UV-visible electronic spectra of three new 2,4-dinitrophenylhydrazone derivatives (C1, C2 and C3) have been studied. Different bands observed have been assigned to the proper electronic transitions. The solvatochromic behaviors of these compounds were investigated by studying their electronic spectra in several organic solvents with different polarities. The longer wavelength band is assigned to an intermolecular charge transfer transition. The solvated H-bonding complexes formed between dimethylformamide and 2,4-dinitrophenylhydrazone derivatives were also investigated. ΔG, and the Kf values of the molecular complexes formed in solution have been determined. Effects of temperature increase and concentration changes on the longer spectroscopic wavelength band of the studied compounds were investigated. In this work, the behavior of acidity constants of these compounds in different pH values is studied by a multiwavelength spectrophotometric method too.

  13. X-ray absorption spectroscopic studies of mononuclear non-heme iron enzymes

    SciTech Connect

    Westre, T.E.

    1996-01-01

    Fe-K-edge X-ray absorption spectroscopy (XAS) has been used to investigate the electronic and geometric structure of the iron active site in non-heme iron enzymes. A new theoretical extended X-ray absorption fine structure (EXAFS) analysis approach, called GNXAS, has been tested on data for iron model complexes to evaluate the utility and reliability of this new technique, especially with respect to the effects of multiple-scattering. In addition, a detailed analysis of the 1s{yields}3d pre-edge feature has been developed as a tool for investigating the oxidation state, spin state, and geometry of iron sites. Edge and EXAFS analyses have then been applied to the study of non-heme iron enzyme active sites.

  14. Impedance spectroscopic characterization of gadolinium substituted cobalt ferrite ceramics

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    Gadolinium (Gd) substituted cobalt ferrites (CoFe2-xGdxO4, 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 CoFe2O4 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.

  15. 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.

  16. Isomerism of Cyanomethanimine: Accurate Structural, Energetic, and Spectroscopic Characterization.

    PubMed

    Puzzarini, Cristina

    2015-11-25

    The structures, relative stabilities, and rotational and vibrational parameters of the Z-C-, E-C-, and N-cyanomethanimine isomers have been evaluated using state-of-the-art quantum-chemical approaches. Equilibrium geometries have been calculated by means of a composite scheme based on coupled-cluster calculations that accounts for the extrapolation to the complete basis set limit and core-correlation effects. The latter approach is proved to provide molecular structures with an accuracy of 0.001-0.002 and 0.05-0.1 for bond lengths and angles, respectively. Systematically extrapolated ab initio energies, accounting for electron correlation through coupled-cluster theory, including up to single, double, triple, and quadruple excitations, and corrected for core-electron correlation and anharmonic zero-point vibrational energy, have been used to accurately determine relative energies and the Z-E isomerization barrier with an accuracy of about 1 kJ/mol. Vibrational and rotational spectroscopic parameters have been investigated by means of hybrid schemes that allow us to obtain rotational constants accurate to about a few megahertz and vibrational frequencies with a mean absolute error of ?1%. Where available, for all properties considered, a very good agreement with experimental data has been observed. PMID:26529434

  17. Thermal, spectroscopic, and ab initio structural characterization of carprofen polymorphs.

    PubMed

    Bruni, Giovanna; Gozzo, Fabia; Capsoni, Doretta; Bini, Marcella; Macchi, Piero; Simoncic, Petra; Berbenni, Vittorio; Milanese, Chiara; Girella, Alessandro; Ferrari, Stefania; Marini, Amedeo

    2011-06-01

    Commercial and recrystallized polycrystalline samples of carprofen, a nonsteroidal anti-inflammatory drug, were studied by thermal, spectroscopic, and structural techniques. Our investigations demonstrated that recrystallized sample, stable at room temperature (RT), is a single polymorphic form of carprofen (polymorph I) that undergoes an isostructural polymorphic transformation by heating (polymorph II). Polymorph II remains then metastable at ambient conditions. Commercial sample is instead a mixture of polymorphs I and II. The thermodynamic relationships between the two polymorphs were determined through the construction of an energy/temperature diagram. The ab initio structural determination performed on synchrotron X-Ray powder diffraction patterns recorded at RT on both polymorphs allowed us to elucidate, for the first time, their crystal structure. Both crystallize in the monoclinic space group type P2(1) /c, and the unit cell similarity index and the volumetric isostructurality index indicate that the temperature-induced polymorphic transformation I ? II is isostructural. Polymorphs I and II are conformational polymorphs, sharing a very similar hydrogen bond network, but with different conformation of the propanoic skeleton, which produces two different packing. The small conformational change agrees with the low value of transition enthalpy obtained by differential scanning calorimetry measurements and the small internal energy computed with density functional methods. PMID:21246561

  18. Electron Spin Resonance and optical absorption spectroscopic studies of manganese centers in aluminium lead borate glasses.

    PubMed

    SivaRamaiah, G; LakshmanaRao, J

    2012-12-01

    Electron Spin Resonance (ESR) and optical absorption studies of 5Al(2)O(3)+75H(3)BO(3)+(20-x)PbO+xMnSO(4) (where x=0.5, 1,1.5 and 2 mol% of MnSO(4)) glasses at room temperature have been studied. The ESR spectrum of all the glasses exhibits resonance signals with effective isotropic g values at ?2.0, 3.3 and 4.3. The ESR resonance signal at isotropic g?2.0 has been attributed to Mn(2+) centers in an octahedral symmetry. The ESR resonance signals at isotropic g?3.3 and 4.3 have been attributed to the rhombic symmetry of the Mn(2+) ions. The zero-field splitting parameter (zfs) has been calculated from the intensities of the allowed hyperfine lines. The optical absorption spectrum exhibits an intense band in the visible region and it has been attributed to (5)E(g)?(5)T(2g) transition of Mn(3+)centers in an octahedral environment. The optical band gap and the Urbach energies have been calculated from the ultraviolet absorption edges. PMID:23000927

  19. Spectroscopic investigation of amber color silicate glasses and factors affecting the amber related absorption bands.

    PubMed

    Morsi, Morsi M; El-Sherbiny, Samya I; Mohamed, Karam M

    2015-06-15

    The effects of carbon, Fe2O3 and Na2SO4 contents on the amber color of glass with composition (wt%) 64.3 SiO2, 25.7 CaO, 10 Na2O were studied. The effect of some additives that could be found in glass batch or cullets on the amber related absorption band(s) was also studied. An amber related absorption band due to the chromophore Fe(3+)O3S(2-) was recorded at 420 nm with shoulder at 440 nm. A second amber related band recorded at 474 nm with shoulder at 483 nm was assigned to FeS. Increasing melting time at 1400C up to 6h caused fainting of the amber color, decreases the intensities of the amber related bands and shifted the first band to 406 nm. Addition of ZnO, Cu2O and NaNO3 to the glass produced decolorizing effect and vanishing of the amber related bands. The effects of melting time and these additives were explained on the bases of destruction the amber chromophore and its conversion into Fe(3+) in tetrahedral sites or ZnS. Addition of Se intensifies the amber related bands and may cause dark coloration due to the formation of Se and polyselenide. Amber color can be monitored through measuring the absorption in the range 406-420 nm. PMID:25795612

  20. Spectroscopic investigation of amber color silicate glasses and factors affecting the amber related absorption bands

    NASA Astrophysics Data System (ADS)

    Morsi, Morsi M.; El-sherbiny, Samya I.; Mohamed, Karam M.

    2015-06-01

    The effects of carbon, Fe2O3 and Na2SO4 contents on the amber color of glass with composition (wt%) 64.3 SiO2, 25.7 CaO, 10 Na2O were studied. The effect of some additives that could be found in glass batch or cullets on the amber related absorption band(s) was also studied. An amber related absorption band due to the chromophore Fe3+O3S2- was recorded at 420 nm with shoulder at 440 nm. A second amber related band recorded at 474 nm with shoulder at 483 nm was assigned to FeS. Increasing melting time at 1400 C up to 6 h caused fainting of the amber color, decreases the intensities of the amber related bands and shifted the first band to 406 nm. Addition of ZnO, Cu2O and NaNO3 to the glass produced decolorizing effect and vanishing of the amber related bands. The effects of melting time and these additives were explained on the bases of destruction the amber chromophore and its conversion into Fe3+ in tetrahedral sites or ZnS. Addition of Se intensifies the amber related bands and may cause dark coloration due to the formation of Se and polyselenide. Amber color can be monitored through measuring the absorption in the range 406-420 nm.

  1. Detailed Spectroscopic Characterization of an Expanding Flashboard Plasma

    NASA Astrophysics Data System (ADS)

    Tsigutkin, K.; Arad, R.; Ralchenko, Yu. V.; Maron, Y.

    1998-11-01

    Spectroscopic investigations of the plasma properties in a 400 ns, 160 kA Plasma Opening Switch (POS) are performed. A flashboard plasma source driven by a 100 kA current pulse is positioned 3 cm above the planar anode. By locally doping the plasma with various gases and observing characteristic emission from the doped gas beam we obtain results that are local in 3D. We measured the spatial distribution of the electron density as a function of time from Stark broadening of hydrogen lines. The density at the beginning of POS pulse (1.2 ? s after the flashboard discharge) was found to be 7 10^14 cm-3 near the anode and 3 10^14 cm-3 near the cathode. The electron temperature and the composition are studied from line intensities and collisional-radiative calculations. The temperature was found to drop in time from 12 2 eV to 6 1 eV at t=1.2 ? s. Analysis of the plasma composition shows, that initially the plasma consists only of protons with an expansion velocity of 1-1.5 10^7 cm/s. At the moment of POS operation the density of carbon (mainly CIV) is substantial only near the anode (? 20%). The expansion velocity of carbon ions is 3-4 10^6 cm/s. The density of other impurities such as oxygen, silicon, iron, copper and nickel is negligible at that time. Also, investigations of the magnetic field distribution from Zeeman splitting, the electron density from line intensities, and ion velocities from Doppler shifts during the POS conduction and opening phases will be presented.

  2. Spectroscopic characterization and aggregation of azine compounds in different media

    NASA Astrophysics Data System (ADS)

    Urrutia, Mara Noel; Ortiz, Cristina Susana

    2013-02-01

    In this study, we have reported for the first time a complete experimental investigation on the compound Neutral Red and the new monobrominated derivative in different media as a function of the concentration. These compounds belong to the quinone-imine class of dyes and have good potential to be applied as photosensitizers in Photodynamic Therapy. Although the aggregation of Neutral Red has been reported by several authors, this has not been thoroughly evaluated due to spectral changes occurring depending on the solvent and concentration of dye. We investigated and compared the effects of aggregation properties in water, ethanol, water-ethanol mixtures, water-polyethylene glycol 400 (75:25 v/v) and N,N-dimethylformamide. An analysis of the changes in the absorption spectra with respect to the solvent as a function of dye concentration together with theoretical calculations confirmed the monomeric species and the formation of different types of aggregates in this class of compounds.

  3. ACCURATE SPECTROSCOPIC CHARACTERIZATION OF PROTONATED OXIRANE: A POTENTIAL PREBIOTIC SPECIES IN TITAN’S ATMOSPHERE

    PubMed Central

    Puzzarini, Cristina; Ali, Ashraf; Biczysko, Malgorzata; Barone, Vincenzo

    2015-01-01

    An accurate spectroscopic characterization of protonated oxirane has been carried out by means of state-of-the-art computational methods and approaches. The calculated spectroscopic parameters from our recent computational investigation of oxirane together with the corresponding experimental data available were used to assess the accuracy of our predicted rotational and IR spectra of protonated oxirane. We found an accuracy of about 10 cm−1 for vibrational transitions (fundamentals as well as overtones and combination bands) and, in relative terms, of 0.1% for rotational transitions. We are therefore confident that the spectroscopic data provided herein are a valuable support for the detection of protonated oxirane not only in Titan’s atmosphere but also in the interstellar medium. PMID:26543241

  4. Accurate spectroscopic characterization of protonated oxirane: a potential prebiotic species in Titan's atmosphere

    SciTech Connect

    Puzzarini, Cristina; Ali, Ashraf; Biczysko, Malgorzata; Barone, Vincenzo

    2014-09-10

    An accurate spectroscopic characterization of protonated oxirane has been carried out by means of state-of-the-art computational methods and approaches. The calculated spectroscopic parameters from our recent computational investigation of oxirane together with the corresponding experimental data available were used to assess the accuracy of our predicted rotational and IR spectra of protonated oxirane. We found an accuracy of about 10 cm{sup 1} for vibrational transitions (fundamentals as well as overtones and combination bands) and, in relative terms, of 0.1% for rotational transitions. We are therefore confident that the spectroscopic data provided herein are a valuable support for the detection of protonated oxirane not only in Titan's atmosphere but also in the interstellar medium.

  5. Atomic absorption spectroscopic, conductometric and colorimetric methods for determination of some fluoroquinolone antibacterials using ammonium reineckate

    NASA Astrophysics Data System (ADS)

    Al-Ghannam, Sheikha M.

    2008-04-01

    Three accurate, rapid and simple atomic absorption spectrometric (AAS), conductometric and colorimetric methods were developed for the determination of gatifloxacin (GTF), moxifloxacin (MXF) and sparfloxacin (SPF). The proposed methods depend upon the reaction of ammonium reineckate with the studied drugs to form stable precipitate of ion-pair complexes, which was dissolved in acetone. The pink coloured complexes were determined either by AAS or colorimetrically at ?max 525 nm directly using the dissolved complex. Using conductometric titration, the studied drugs could be evaluated in 50% (v/v) acetone. The optimizations of various experimental conditions were described. Optimum concentration ranges for the determination of GTF, MXF and SPF were 5.0-150, 40-440 ?g mL -1 and 0.10-1.5 mg mL -1 using atomic absorption (AAS), conductometric and colorimetric methods, respectively. Detection and quantification limits are ranges from 1.5 to 2.3 ?g mL -1 using AAS method or 30-45 ?g mL -1 using colorimetric method. The proposed procedures have been applied successfully to the analysis of these drugs in pharmaceutical formulations and the results are favourably comparable to the reference methods.

  6. Characterization of female breasts in vivo by time-resolved and spectroscopic measurements in the near infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Heusmann, Hans; Koelzer, Jochen G.; Mitic, Gerhard

    1996-10-01

    Time-resolved and spectroscopic in vivo measurements were performed to determine the optical properties of the female breast in transmission. The time-resolved measurements were carried out at different positions on the female breast with a Ti:sapphire laser using as synchroscan steak camera. A diffusion model was used to calculate the absorption coefficient (mu) A and the reduced scattering coefficient. In addition, spectroscopic in vivo measurements of more than 100 patients were performed in a wavelength range between 650 and 1000 nm. A variety of pathological alterations could be characterized by measuring patients of different ages, different breast sizes, and at carrying locations on the breast. The results indicate that besides the pure detection of the amount of blood in the neovascular network, the volume concentrations of water and fat model was developed that takes the volume percentages of fat and water, the concentration and oxygenation of hemoglobin, and the relevant optical parameters into account. Experiments were carried out with volunteers and patients in a clinical environment: typical observations are presented and analyzed statistically.

  7. Spectroscopic Characterization of Mineralogy Across Vesta: Evidence of Different Lithologies

    NASA Technical Reports Server (NTRS)

    De Sanotis, M. C.; Ammannito, E.; Filacchione, G.; Capria, M. T.; Tosi, F.; Capaccioni, F.; Zambon, F.; Carraro, F.; Fonte, S.; Frigeri, A.; Jaumann, R.; Magni, G.; Marchi, S.; McCord, T. B.; McFadden, L. A.; McSween, H. Y.; Mittlefehldt, D. W.; Nathues, A.; Palomba, E.; Pieters, C. M.; Raymond, C. A.; Russell, C. T.; Turrini, D.

    2012-01-01

    The average spectrum of Vesta, obtained by VIR in the range 0.25-5.1 microns, shows clear evidence of absorption bands due to pyroxenes and thermal emissions beyond 3.5 11m. Vesta shows considerable variability across its surface in terms of spectral reflectance and emission, band depths, bands widths and bands centers, reflecting a complex geological history. Vesta's average spectrum and inferred mineralogy resemble those of howardite meteorites. On a regional scale, significant deviations are seen: the south polar 500km Rheasilvia impact crater has a higher diogenitic component, and equatorial regions show a higher eucritic component. This lithologic distribution, with a concentration of Mg-pyroxenes in the Rheasilvia area, reinforces the hypothesis of a deeper diogenitic crust excavated by the impact that formed the Rheasilvia crater, and an upper eucritic crust, whose remnants are seen in the equatorial region. This scenario has implications for Vesta differentiation, consistent with magma ocean models. However, serial magmatism models could also have concentrated pyroxene cumulates in plutons emplaced within the lower crust,

  8. Single-Molecule Spectroscopic Characterization of Light-Harvesting 2 Complexes Reconstituted into Model Membranes

    PubMed Central

    Richter, Martin F.; Baier, Jrgen; Cogdell, Richard J.; Khler, Jrgen; Oellerich, Silke

    2007-01-01

    The spectroscopic properties of the light-harvesting 2 complexes (LH2) from the purple bacterium Rhodopseudomonas acidophila (strain 10050) in detergent micelles and reconstituted into lipid membranes have been studied by single-molecule spectroscopy. When LH2 complexes are solubilized from their host biological membranes by nondenaturing detergents, such as LDAO, there is a small 2-nm spectral shift of the B850 absorption band in the ensemble spectrum. This is reversed when the LH2 complexes are put back into phospholipid vesicles, i.e., into a more native-like environment. The spectroscopic properties on the single-molecule level of the detergent-solubilized LH2 complexes were compared with those reconstituted into the lipid membranes to see if their detailed spectroscopic behavior was influenced by these small changes in the position of the B850 absorption band. A detailed analysis of the low-temperature single-molecule fluorescence-excitation spectra of the LH2 complexes in these two different conditions showed no significant differences. In particular, the distribution of the spectral splitting between the circular k = 1 exciton states of the B850 absorption band and the distribution of the mutual angle between the k = 1 exciton states are identical in both cases. It can be concluded, therefore, that the LH2 complexes from Rps. acidophila are equally stable when solubilized in detergent micelles as they are when membrane reconstituted. Moreover, when they are solubilized in a suitable detergent and spin coated onto a surface for the single-molecule experiments they do not display any more structural disorder than when in a phospholipid membrane. PMID:17416626

  9. Resonance Raman spectroscopic characterization of compound III of lignin peroxidase

    SciTech Connect

    Mylrajan, M.; Valli, K.; Wariishi, Gold, M.H.; Loehr, T.M. )

    1990-10-01

    Resonance Raman (RR) spectra of several compounds III of lignin peroxidase (LiP) have been measured at 90 K with Soret and visible excitation wavelengths. The samples include LiPIIIa (or oxyLiP) prepared by oxygenation of the ferrous enzyme, LiPIIIb generated by reaction of the native ferric enzyme with superoxide, LiPIIIc prepared from native LiP plus H{sub 2}O{sub 2} followed by removal of excess peroxide with catalase, and LiPIII made by addition of excess H{sub 2}O{sub 2} to the native enzyme. The RR spectra of these four products appear to be similar and, thus, indicate that the environments of these hexacoordinate, low-spin ferriheme species must also be very similar. Nonetheless, the Soret absorption band of LiPIII is red-shifted by 5 nm from the 414-nm maximum common to LiPIIIa, -b, and -c. Analysis of the iron-porphyrin vibrational frequencies indicates that the electronic structures for the various compounds III are consistent with an Fe{sup III}O{sub 2}{sup {center dot}-}formulation. The spectral changes observed between the oxygenated complex and the ferrous heme of lignin peroxidase are similar to those between oxymyoglobin and deoxymyoglobin. The contraction in the core sizes in compound III relative to the native peroxidase is analyzed and compared with that of other heme systems. The Fe-O{sub 2} stretching vibration of the oxygenated peroxidase is observed at 563 cm{sup {minus}1} and shifts of 538 cm{sup {minus}1} with {sup 18}O isotope. The Fe-histidine stretching vibration is observed at 245 cm{sup {minus}1} in ferrous peroxidase and appears to shift to 276 cm{sup {minus}1} in the oxygenated complex.

  10. Spectroscopic characterization of nitrogen- and boron-doped graphene layers

    NASA Astrophysics Data System (ADS)

    Kamoi, Susumu; Kim, Jung Gon; Hasuike, Noriyuki; Kisoda, Kenji; Harima, Hiroshi

    2015-11-01

    Nitrogen- and boron-doped graphene layers were grown on copper substrates by alcoholic chemical vapor deposition and characterized by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and electrical transport measurements. The growth of high-quality monolayer graphene was confirmed by micro-Raman spectroscopy. The G and 2D peaks showed systematic frequency shift and broadening with the impurity concentration. The G peaks showed Fano-like asymmetric line shapes. These behaviors suggested the generation of free carriers by doping. XPS and electrical transport measurements also supported the systematic incorporation of impurities in graphene layers.

  11. Spectroscopic characterization of Fe2+-doped II-VI ternary and quaternary mid-IR laser active powders

    NASA Astrophysics Data System (ADS)

    Martinez, A.; Martyshkin, D. V.; Fedorov, V. V.; Mirov, S. B.

    2014-02-01

    We report on spectroscopic characterization of laser active powders based on iron doped II-VI ternary and quaternary semiconductors for mid-IR laser applications. Iron doped Cd1-x MnxTe, Cd1-x MnxS, Cd1-xMnxSe, Cd0.5Mn0.5S0.5Se0.5 , Cd1-xZnxTe compounds with x=0.5-0.25, were prepared by using thermo diffusion technique. The starting binary powders were mixed in the appropriate molar ratios, sealed in evacuated (10-3 Torr) quartz ampoules, and annealed at 800-1000oC for several days. Samples composition, integrity, and grain size were characterized by micro-Raman and Xray diffraction and revealed a variation of the crystal field parameters depending on powder composition. Fe2+ photoluminescence was characterized by spectral band position (normalized with respect to the detection platform spectral sensitivity) and lifetime at different temperatures, enabling calculation of the absorption and emission crosssections. Practical utility of the developed powders was demonstrated by a room temperature random lasing of iron doped Cd0.5Zn0.5Te powders over 5620-6020 nm spectral range pumped by a 2.94 ?m radiation of a Q-switched Er:YAG laser. In summary, the following has been accomplished: (1) It was demonstrated that laser active Fe2+ doped ternary and quaternary II-VI materials can be produced by simple annealing of the commercially available binary powders omitting expensive and complicated crystal growth processes; (2) It is possible to effectively shift PL of Fe2+ in II-VI host materials towards shorter or longer wavelength by varying composition, type and amount of the second cation in ternary II-VI materials; (3) Major spectroscopic characteristics of Fe2+ doped II-VI ternary and quaternary compounds were obtained and their practical utility for mid-IR lasing demonstrated.

  12. [Structural characterization and spectroscopic analysis of the aloin].

    PubMed

    Xie, Yun-Fei; Huan, Nan; Cao, Yuan-Yuan; Wang, He-Ya; Zhong, Ying; Yao, Wei-Rong; Qian, He

    2014-02-01

    Aloe is widely used in various fields for its rich polysaccharides, proteins, amino acids, vitamins, active enzymes and trace beneficial elements to human body. However, the main active ingredient aloin is also an allergenic ingredient, which even may cause a severe allergic reaction In this study, infrared spectroscopy, Raman spectroscopy applied to the structural characterization of the aloin Density functional theory (DFT) is applied to the theoretical calculations using the B3LYP/6-31G (d) basis set vibration, which was helpful to understand the aloin molecular vibrational frequency. By comparing we choose the optimal experimental condition for water as solvent under alkaline conditions, the detection limit of the Aloin can reach a level of 5 ppm, which can be considered the theoretical basis for rapid detection of aloin content. PMID:24822406

  13. Characterization of Sorolla's gouache pigments by means of spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Roldán, Clodoaldo; Juanes, David; Ferrazza, Livio; Carballo, Jorgelina

    2016-02-01

    This paper presents the characterization of the Joaquín Sorolla's gouache sketches for the oil on canvas series "Vision of Spain" commissioned by A. M. Huntington to decorate the library of the Hispanic Society of America in New York. The analyses were focused on the identification of the elemental composition of the gouache pigments by means of portable EDXRF spectrometry in a non-destructive mode. Additionally, SEM-EDX and FTIR analyses of a selected set of micro-samples were carried out to identify completely the pigments, the paint technique and the binding media. The obtained results have confirmed the identification of lead and zinc white, vermillion, earth pigments, ochre, zinc yellow, chrome yellow, ultramarine, Prussian blue, chromium based and copper-arsenic based green pigments, bone black and carbon based black pigments, and the use of gum arabic as binding media in the gouache pigments.

  14. Spectroscopic and morphologic characterization of the dentin/adhesive interface

    NASA Astrophysics Data System (ADS)

    Lemor, R. M.; Kruger, Michael B.; Wieliczka, David M.; Swafford, Jim R.; Spencer, Paulette

    1999-01-01

    The potential environmental risks associated with mercury release have forced many European countries to ban the use of dental amalgam. Alternative materials such as composite resins do not provide the clinical function for the length of time characteristically associated with dental amalgam. The weak link in the composite restoration is the dentin/adhesive bond. The purpose of this study was to correlate morphologic characterization of the dentin/adhesive bond with chemical analyses using micro- Fourier transform infrared and micro-Raman spectroscopy. A commercial dental adhesive was placed on dentin substrates cut from extracted, unerupted human third molars. Sections of the dentin/adhesive interface were investigated using infrared radiation produced at the Aladdin synchrotron source; visible radiation from a Kr+ laser was used for the micro-Raman spectroscopy. Sections of the dentin/adhesive interface, differentially stained to identify protein, mineral, and adhesive, were examined using light microscopy. Due to its limited spatial resolution and the unknown sample thickness the infrared results cannot be used quantitatively in determining the extent of diffusion. The results from the micro-Raman spectroscopy and light microscopy indicate exposed protein at the dentin/adhesive interface. Using a laser that reduces background fluorescence, the micro-Raman spectroscopy provides quantitative chemical and morphologic information on the dentin/adhesive interface. The staining procedure is sensitive to sites of pure protein and thus, complements the Raman results.

  15. Spectroscopic and morphologic characterization of the dentin/adhesive interface

    NASA Astrophysics Data System (ADS)

    Lemor, R. M.; Kruger, Michael B.; Wieliczka, David M.; Swafford, Jim R.; Spencer, Paulette

    1999-04-01

    The potential environmental risks associated with dental amalgams have forced many European countries to ban their use and turn to alternative materials, composite resins. The purpose of this study was to correlate morphologic characterization of the dentin/adhesive bond with chemical analyses using micro-FTIR and micro-Raman spectroscopy. A commercial dental adhesive was placed on dentin substrates cut from extracted, unerupted human third molars. Sections of the dentin/adhesive interface were investigated using IR radiation produced at the Aladdin synchrotron source; visible radiation from Kr+ laser was used for the micro-Raman spectroscopy and through the use of differentially staining in conjunction with light microscopy. Due to its limited spatial resolution and the unknown samples thickness the IR results cannot be used quantitatively in determining the extent of diffusion. The result from the micro-Raman spectroscopy and light microscopy indicate exposed protein at the dentin/adhesive interface. Using a laser that reduces background fluorescence, the micro-Raman spectroscopy provides quantitative chemical and morphologic information on the dentin/adhesive interface. The staining procedure is sensitive to sites of pure protein and complements the Raman results.

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

    PubMed

    Holakooei, Parviz; Niknejad, Maryam; Vaccaro, Carmela

    2016-01-01

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

  17. Crystal structure characterization as well as theoretical study of spectroscopic properties of novel Schiff bases containing pyrazole group

    NASA Astrophysics Data System (ADS)

    Guo, Jia; Ren, Tiegang; Zhang, Jinglai; Li, Guihui; Li, Weijie; Yang, Lirong

    2012-09-01

    A series of novel Schiff bases containing pyrazole group were synthesized using 1-aryl-3-methyl-4-benzoyl-5-pyrazolone and phenylenediamine as the starting materials. All as-synthesized Schiff bases were characterized by means of NMR, FT-IR, and MS; and the molecular geometries of two Schiff bases as typical examples were determined by means of single crystal X-ray diffraction. In the meantime, the ultraviolet-visible light absorption spectra and fluorescent spectra of various as-synthesized products were also measured. Moreover, the B3LYP/6-1G(d,p) method was used for the optimization of the ground state geometry of the Schiff bases; and the spectroscopic properties of the products were computed and compared with corresponding experimental data based on cc-pVTZ basis set of TD-B3LYP method. It has been found that all as-synthesized Schiff bases show a remarkable absorption peak in a wavelength range of 270-370 nm; and their maximum emission peaks are around 344 nm and 332 nm, respectively.

  18. Flash spectroscopic characterization of photosynthetic electron transport in isolated heterocysts

    SciTech Connect

    Houchins, J.P.; Hind, G.

    1983-07-01

    Electron transport was studied in heterocysts of the filamentous cyanobacterium Anabaena 7120 using spectral and kinetic analysis of absorbance transients elicited by single turnover flashes. Consistent photosynthetic turnovers were observed only in the presence of an exogenous source of reductant; therefore measurements were routinely made under a gas phase containing H2. Prominent absorbance changes corresponding to the oxidation of cytochrome c (554 nm) and the reduction of cytochrome b563 (563 nm) were observed. Under the most reducing conditions (99% H2/1% O2) cytochrome b563 was partially reduced between flashes in a slow, dark reaction. At 10-15% O2, the slow, dark reduction of cytochrome b563 was eliminated. Cytochrome turnover ceased entirely at high O2 concentrations (30%) but was restored by the addition of 25 microM KCN, demonstrating an interaction between the photosynthetic and respiratory electron transfer chains. Strobilurin A slowed the re-reduction of cytochrome c and eliminated the appearance of reduced cytochrome b563 by blocking electron transfer between reduced plastoquinone and the cytochrome b/f complex. Inhibition at a second site was apparent with 2-(n-heptyl)-4-hydroxyquinoline N-oxide, which blocked the reoxidation of cytochrome b563 but had little effect on cytochrome c relaxation. In uncoupled heterocysts, the rates of cytochrome c re-reduction and cytochrome b563 reduction were equal. Additional unassigned absorbance changes at 475 nm, 515 nm, and 572 nm were partially characterized. No absorbance change corresponding to an electrochromic shift was observed.

  19. Behavioral mutants of Euglena gracilis: functional and spectroscopic characterization.

    PubMed

    Lebert, M; Hader, D P

    1997-08-01

    Three mutant strains of the phytoflagellate Euglena gracilis Z have been characterized in order to analyze the signal perception and signal transduction pathways involved in photo- and gravitaxis. Using the fluorescence of the chromophoric groups believed to be involved in photoperception (flavins and pterins) a method was developed for an in situ and in vivo detection of the paraxonemal body, the proposed location of the photoreceptor molecules. Two of the mutant strains, 1224-5/9f and 1224-5/1f, do not possess a stigma and also lack a paraxonemal body, as indicated by fluorescence measurements. The third strain, FB, has a small stigma, but only some cells contain a paraxonemal body. In contrast to the present hypothesis on photoorientation of Euglena, all strains were able to orient with respect to the light direction. However, the mutant strains did not show any orientation at low irradiances. At medium and high irradiances the strains 1224-5/9f and 1224-5/1f oriented perpendicular to the light direction (diaphototaxis) while cells of strains of FB showed partly negative phototaxis and partly diaphototaxis. Diaphototaxis was never observed in the wild type strain. Strains 1224-5/9f and 1224-5/1f showed normal graviresponses compared with the wild type. Astasia longa, a nonphtototactic relative of E. gracilis, as well as strain FB were both negative and positive gravitactic at all culture ages tested. This result confirmed the hypothesis that the paraxonemal body is not directly involved in graviperception. PMID:11540955

  20. Synthesis and spectroscopic characterization of copper zinc aluminum nanoferrite particles

    NASA Astrophysics Data System (ADS)

    Lakshmi Reddy, S.; Ravindra Reddy, T.; Roy, Nivya; Philip, Reji; Montero, Ovidio Almanza; Endo, Tamio; Frost, Ray L.

    2014-06-01

    Copper doped zinc aluminum ferrites CuxZn1-x.(AlxFe2-x)O4 are synthesized by the solid-state reaction route and characterized by XRD, TEM, EPR and non linear optical spectroscopy techniques. The average particle size is found to be from 35 to 90 nm and the unit cell parameter “a” is calculated as from 8.39 to 8.89 Å. The cation distributions are estimated from X-ray diffraction intensities of various planes. The XRD studies have verified the quality of the synthesis of compounds and have shown the differences in the positions of the diffraction peaks due to the change in concentration of copper ions. TEM pictures clearly indicating that fundamental unit is composed of octahedral and tetrahedral blocks and joined strongly. The selected area electron diffraction (SAED) of the ferrite system shows best crystallinity is obtained when Cu content is very. Some of the d-plane spacings are exactly coinciding with XRD values. EPR spectra is compositional dependent at lower Al/Cu concentration EPR spectra is due to Fe3+ and at a higher content of Al/Cu the EPR spectra is due to Cu2+. Absence of EPR spectra at room temperature indicates that the sample is perfectly ferromagnetic. EPR results at low temperature indicate that the sample is paramagnetic, and that copper is placed in the tetragonal elongation (B) site with magnetically non-equivalent ions in the unit cell having strong exchange coupling between them. This property is useful in industrial applications. Nonlinear optical properties of the samples studied using 5 ns laser pulses at 532 nm employing the open aperture z-scan technique indicate that these ferrites are potential candidates for optical limiting applications.

  1. Quaoar: New, Longitudinaly Resolved, Spectroscopic Characterization of Its Surface

    NASA Technical Reports Server (NTRS)

    Ore, C. M. Dalle; Barucci, M. A.; Cruikshank, D. P.; Alunni, Antonella

    2014-01-01

    (50000) Quaoar, one of the largest Trans-neptunian objects, is comparable in size to Pluto's moon Charon. However, while Charon's surface is rich almost exclusively in H2O ice, Quaoar's surface characterized by ices of CH4, N2, as well as C2H6, a product of irradiation of CH4 (Dalle Ore et al. 2009). Because of its distance from the Sun, Quaoar is expected to have preserved, to a degree, its original composition, however, its relatively small size did not make it a prime candidate for presence of volatile ices in the study by Schaller and Brown (2007). Furthermore, based on the Brown et al. (2011) study (Brown, Schaller, & Fraser, 2011. A Hypothesis for the Color Diversity of the Kuiper Belt. ApJL, 739, L60) its red coloration points to CH3OH as the ice which, when irradiated, might have produced the red material. We present new visible to near-infrared (0.3-2.48 micrometers) spectro-photometric data obtained with the XSHOOTER (Vernet et al. 2011, A&A, 536A, 105 ) instrument at the VLT-ESO facility at four different longitudes on the surface of Quaoar. The data are complemented by previously published photometric observations obtained in the near-infrared (3.6, 4.5 micrometers) with the Spitzer Space Telescope, which provide an extra set of constraints in the model calculation process in spite of the different observing times that preclude establishing the spatial consistency between the two sets. For each of the four spectra we perform spectral modeling of the entire wavelength range -from 0.3 to 4.5 micrometers- by means of a code based on the Shkuratov radiative transfer formulation of the slab model. We obtain spatially resolved compositional information for the surface of Quaoar supporting the presence of CH4 and C2H6, as previously reported, along with evidence for N2 and NH3OH. The albedo at the two Spitzer bands indicates the likely presence of CO and CO2. CH3OH, predicted on the basis of Quaoar's coloration (Brown et al. 2011), is not found at any of the four longitudes, implying that the presence of this ice is a sufficient, but not necessary condition for reddening of TNO surfaces. Other ices, in particular CH4 (Brunetto et al. 2006), have been shown to be plausible precursors for reddening of TNO surfaces.

  2. Spectroscopic characterization of dissolved organic matter in coking wastewater during bio-treatment: full-scale plant study.

    PubMed

    Xu, Ronghua; Ou, Huase; Yu, Xubiao; He, Runsheng; Lin, Chong; Wei, Chaohai

    2015-01-01

    This paper taking a full-scale coking wastewater (CWW) treatment plant as a case study aimed to characterize removal behaviors of dissolved organic matter (DOM) by UV spectra and fluorescence excitation-emission matrix-parallel factor analysis (PARAFAC), and investigate the correlations between spectroscopic indices and water quality parameters. Efficient removal rates of chemical oxygen demand (COD), dissolved organic carbon (DOC) and total nitrogen (TN) after the bio-treatment were 91.3%, 87.3% and 69.1%, respectively. UV270 was proven to be a stable UV absorption peak of CWW that could reflect the mixture of phenols, heterocyclics, polynuclear aromatic hydrocarbons and their derivatives. Molecular weight and aromaticity were increased, and also the content of polar functional groups was greatly reduced after bio-treatment. Three fluorescent components were identified by PARAFAC: C1 (tyrosine-like), C2 (tryptophan-like) and C3 (humic-like). The removal rate of protein-like was higher than that of humic-like and C1 was identified as biodegradable substance. Correlation analysis showed UV270 had an excellent correlation with COD (r=0.921, n=60, P<0.01) and DOC (r=0.959, n=60, P<0.01) and significant correlation (r=0.875, n=60, P<0.01) was also found between C2 and TN. Therefore, spectroscopic characterization could provide novel insights into removal behaviors of DOM and potential to monitor water quality real-time during CWW bio-treatment. PMID:26465313

  3. Spectroscopic and functional characterization of iron-bound forms of Azotobacter vinelandii (Nif)IscA.

    PubMed

    Mapolelo, Daphne T; Zhang, Bo; Naik, Sunil G; Huynh, Boi Hanh; Johnson, Michael K

    2012-10-16

    The ability of Azotobacter vinelandii(Nif)IscA to bind Fe has been investigated to assess the role of Fe-bound forms in NIF-specific Fe-S cluster biogenesis. (Nif)IscA is shown to bind one Fe(III) or one Fe(II) per homodimer and the spectroscopic and redox properties of both the Fe(III)- and Fe(II)-bound forms have been characterized using the UV-visible absorption, circular dichroism, and variable-temperature magnetic circular dichroism, electron paramagnetic resonance, Mssbauer and resonance Raman spectroscopies. The results reveal a rhombic intermediate-spin (S = 3/2) Fe(III) center (E/D = 0.33, D = 3.5 1.5 cm(-1)) that is most likely 5-coordinate with two or three cysteinate ligands and a rhombic high spin (S = 2) Fe(II) center (E/D = 0.28, D = 7.6 cm(-1)) with properties similar to reduced rubredoxins or rubredoxin variants with three cysteinate and one or two oxygenic ligands. Iron-bound (Nif)IscA undergoes reversible redox cycling between the Fe(III)/Fe(II) forms with a midpoint potential of +36 15 mV at pH 7.8 (versus NHE). l-Cysteine is effective in mediating release of free Fe(II) from both the Fe(II)- and Fe(III)-bound forms of (Nif)IscA. Fe(III)-bound (Nif)IscA was also shown to be a competent iron source for in vitro NifS-mediated [2Fe-2S] cluster assembly on the N-terminal domain of NifU, but the reaction occurs via cysteine-mediated release of free Fe(II) rather than direct iron transfer. The proposed roles of A-type proteins in storing Fe under aerobic growth conditions and serving as iron donors for cluster assembly on U-type scaffold proteins or maturation of biological [4Fe-4S] centers are discussed in light of these results. PMID:23003563

  4. Spectroscopic and ultrasonic investigations on structural characterization of borate glass specimen doped with transition metal ions

    NASA Astrophysics Data System (ADS)

    Sathish, K.; Thirumaran, S.

    2015-08-01

    The present work describes the glass samples of composition (x% V2O5-(80-x)% B2O3-20% Na2CO3) VBS glass system and (x% MnO2-(80-x)% B2O3-20% Na2CO3) in MBS glass system with mol% ranging from x = 3, 6, 9, 12, 15 and 18 in steps of 3 mol% are prepared by melt quenching technique. For these prepared glass systems, sound velocity (longitudinal and shear velocities) and density have been measured. The sound velocity (longitudinal and shear) was measured by using pulse-echo technique at 5 MHz. The XRD study was carried to out to ascertain the amorphous nature of the glass specimen. Using these measured values, the elastic moduli, Poisson's ratio, Debye temperature, acoustic impedance and thermal expansion coefficient of the two glass systems were evaluated. The elastic and mechanical properties of the prepared glass systems are analyzed from ultrasonic study and the structural characterization from spectroscopic study. The effects due to the doping of transition metal ions with borate have been discussed. In the V2O5 doped glass system, (VBS glass system) the sound velocity, density and elastic moduli, steeply increases after 12 mol% comparatively with MnO2 doped glass system (VBS glass system). The present study critically observes the doping of V2O5 with borate enhances the strengthening of network linkage and hardening of the glassy network structure than MnO2. The IR spectral analysis reveals depolymerization of the borate network and conversion of BO3 or BO4 units with the formation of non-bridging oxygen. The FTIR spectral studies confirm the presence of various functional groups of the sample. FTIR spectrum of sample exhibits broad absorption bands indicating the wide distribution of borate structural units. The effect of Na2CO3, V2O5 and MnO2 contents on the structures of borate glass is evaluated from the FTIR spectra. The topological aspects of the prepared glass samples are exhaustively reported from SEM micrographs.

  5. Spectroscopic and ultrasonic investigations on structural characterization of borate glass specimen doped with transition metal ions.

    PubMed

    Sathish, K; Thirumaran, S

    2015-08-01

    The present work describes the glass samples of composition (x% V₂O₅-(80-x)% B₂O₃-20% Na₂CO₃) VBS glass system and (x%MnO₂-(80-x)% B₂O₃-20% Na₂CO₃) in MBS glass system with mol% ranging from x=3, 6, 9, 12, 15 and 18 in steps of 3 mol% are prepared by melt quenching technique. For these prepared glass systems, sound velocity (longitudinal and shear velocities) and density have been measured. The sound velocity (longitudinal and shear) was measured by using pulse-echo technique at 5 MHz. The XRD study was carried to out to ascertain the amorphous nature of the glass specimen. Using these measured values, the elastic moduli, Poisson's ratio, Debye temperature, acoustic impedance and thermal expansion coefficient of the two glass systems were evaluated. The elastic and mechanical properties of the prepared glass systems are analyzed from ultrasonic study and the structural characterization from spectroscopic study. The effects due to the doping of transition metal ions with borate have been discussed. In the V₂O₅ doped glass system,(VBS glass system) the sound velocity, density and elastic moduli, steeply increases after 12 mol% comparatively with MnO₂ doped glass system (VBS glass system). The present study critically observes the doping of V₂O₅ with borate enhances the strengthening of network linkage and hardening of the glassy network structure than MnO₂. The IR spectral analysis reveals depolymerization of the borate network and conversion of BO₃ or BO4 units with the formation of non-bridging oxygen. The FTIR spectral studies confirm the presence of various functional groups of the sample. FTIR spectrum of sample exhibits broad absorption bands indicating the wide distribution of borate structural units. The effect of Na₂CO₃, V₂O₅ and MnO₂ contents on the structures of borate glass is evaluated from the FTIR spectra. The topological aspects of the prepared glass samples are exhaustively reported from SEM micrographs. PMID:25841150

  6. Spectroscopic and Functional Characterization of Iron-Bound Forms of Azotobacter vinelandiiNifIscA

    PubMed Central

    Mapolelo, Daphne T.; Zhang, Bo; Naik, Sunil G.; Huynh, Boi Hanh; Johnson, Michael K.

    2012-01-01

    The ability of Azotobacter vinelandii NifIscA to bind Fe has been investigated to assess the role of Fe-bound forms in NIF-specific Fe-S cluster biogenesis. NifIscA is shown to bind one Fe(III) or one Fe(II) per homodimer and the spectroscopic and redox properties of both the Fe(III)- and Fe(II)-bound forms have been characterized using the UV-visible absorption, CD and VTMCD, EPR, Mssbauer and resonance Raman spectroscopies. The results reveal a rhombic intermediate-spin (S = 3/2) Fe(III) center (E/D = 0.33, D = 3.5 1.5cm?1) that is most likely 5-coordinate with two or three cysteinate ligands and a rhombic high spin (S = 2) Fe(II) center (E/D = 0.28, D = 7.6 cm?1) with properties similar to reduced rubredoxins or rubredoxin variants with three cysteinate and one or two oxygenic ligands. Iron-bound NifIscA undergoes reversible redox cycling between the Fe(III)/Fe(II) forms with a midpoint potential of +36 15 mV at pH 7.8 (versus NHE). L-cysteine is effective in mediating release of free Fe(II) from both the Fe(II)- and Fe(III)-bound forms of NifIscA. Fe(III)-bound NifIscA was also shown to a competent iron source for in vitro NifS-mediated [2Fe-2S] cluster assembly on the N-terminal domain of NifU, but the reaction occurs via cysteine-mediated release of free Fe(II) rather than direct iron transfer. The proposed roles of A-type proteins in storing Fe under aerobic growth conditions and serving as iron donors for cluster assembly on U-type scaffold proteins or maturation of biological [4Fe-4S] centers are discussed in light of these results. PMID:23003563

  7. Valence states of bismuth and thallium in superconducting cuprates; A Bi-L sub 3 and Tl-L sub 3 x-ray absorption spectroscopic study

    SciTech Connect

    Vijayakrishnan, V.; Kulkarni, G.U.; Rao, C.N.R. . Solid State and Structural Chemistry Unit)

    1990-04-01

    Based on a Bi-L{sub 3} edge X-ray absorption spectroscopic study of superconducting bismuth cuprates and model Bi compounds, it is shown that Bi is essentially in the 3{plus} state in the cuprates. Tl-L{sub 3} absorption edge studies a number of thallium cuprate superconductors along with those of model compounds show some evidence for the occupancy of the Tl-5s band, but Tl{sup 3+} is the prepondarant species. Cu K-edge studies of the thallium cuprates show that Cu is essentially in the 2+ state.

  8. Spectroscopic ellipsometry study of the free-carrier and band-edge absorption in ZnO thin films: Effect of non-stoichiometry

    NASA Astrophysics Data System (ADS)

    Singh, Chaman; Nozaki, Shinji; Rath, Shyama

    2015-11-01

    The effect of stoichiometry on the complex dielectric function (?(E) = ?1(E) + i?2(E)), and thereby on the optical and electrical properties, of rf-sputtered polycrystalline ZnO films was investigated using spectroscopic ellipsometry in the UV-VIS-NIR range. The stoichiometry and the density of the films were quantified by Rutherford backscattering spectroscopy. The lineshape of the dielectric function was fitted using the Tauc-Lorentz multi-oscillator and Drude models. The stoichiometric as well as the sub-stoichiometric films showed a high optical transparency in the visible and a bandgap absorption in the UV region. In the NIR region, however, the sub-stoichiometric films showed a significant increase in absorption with decreasing energy while the absorption was negligible for the stoichiometric films. This difference in behavior is attributed to the presence of free-carriers in the sub-stoichiometric films, whose concentration was determined to be around 4 1020 cm-3 from spectroscopic ellipsometry. The high carrier concentration induced by non-stoichiometry is also manifested in a larger value of the optical bandgap. This study shows the power of spectroscopic ellipsometry for the simultaneous determination of the electrical and optical properties of ZnO films and is applicable for a wide range of film thickness.

  9. Spectroscopic characterization of alumina-supported bis(allyl)iridium complexes : site-isolation, reactivity, and decomposition studies.

    SciTech Connect

    Trovitch, R. J.; Guo, N.; Janicke, M. T.; Li, H.; Marshall, C. L.; Miller, J. T.; Sattelberger, A. P.; John, K. D.; Baker, R. T.; LANL; Univ. of Ottawa

    2010-01-01

    The covalent attachment of tris(allyl)iridium to partially dehydroxylated ?-alumina is found to proceed via surface hydroxyl group protonation of one allyl ligand to form an immobilized bis(allyl)iridium moiety, (?AlO)Ir(allyl)2, as characterized by CP-MAS 13C NMR, inductively coupled plasma-mass spectrometry, and Ir L3 edge X-ray absorption spectroscopy. Extended X-ray absorption fine-structure (EXAFS) measurements taken on unsupported Ir(allyl)3 and several associated tertiary phosphine addition complexes suggest that the ?3-allyl ligands generally account for an Ir-C coordination number of 2 rather than 3, with an average Ir-C distance of 2.16 A. Using this knowledge, combined EXAFS and X-ray absorption near-edge structure studies reveal that a small amount of Ir0 is also formed upon reaction of Ir(allyl)3 with the surface. It was found that the addition of either 2,6-dimethylphenyl isocyanide or carbon monoxide to the supported complex allows spectroscopic identification of the supported bis(allyl)iridium complexes, (?AlO)Ir(allyl)2(CNAr) [Ar = 2,6-(CH3)2C6H4] and (?AlO)Ir(allyl)2(CO)2, respectively. Although samples of the supported bis(allyl)iridium complex are active for the dehydrogenation of cyclohexane to benzene at temperatures between 180 and 220C, in situ temperature-programmed reaction XAFS and continuous-flow reactor studies suggest that Ir0 nanoparticles, rather than a well-defined Ir3+ complex, are responsible for the observed activity.

  10. Reactivity of Chromium(III) Nutritional Supplements in Biological Media: An X-Ray Absorption Spectroscopic Study

    SciTech Connect

    Nguyen, A.; Mulyani, I.; Levina, A.; Lay, P.A.

    2009-05-22

    Chromium(III) nutritional supplements are widely used due to their purported ability to enhance glucose metabolism, despite growing evidence on low activity and the potential genotoxicity of these compounds. Reactivities of Cr(III) complexes used in nutritional formulations, including [Cr3O(OCOEt)6(OH2)3]+ (A), [Cr(pic)3] (pic) = 2-pyridinecarboxylato(-) (B), and trans-[CrCl2(OH2)4]+ (CrCl3 {center_dot} 6H2O; C), in a range of natural and simulated biological media (artificial digestion systems, blood and its components, cell culture media, and intact L6 rat skeletal muscle cells) were studied by X-ray absorption near-edge structure (XANES) spectroscopy. The XANES spectroscopic data were processed by multiple linear-regression analyses with the use of a library of model Cr(III) compounds, and the results were corroborated by the results of X-ray absorption fine structure spectroscopy and electrospray mass spectrometry. Complexes A and B underwent extensive ligand-exchange reactions under conditions of combined gastric and intestinal digestion (in the presence of a semisynthetic meal, 3 h at 310 K), as well as in blood serum and in a cell culture medium (1-24 h at 310 K), with the formation of Cr(III) complexes with hydroxo and amino acid/protein ligands. Reactions of compounds A-C with cultured muscle cells led to similar ligand-exchange products, with at least part of Cr(III) bound to the surface of the cells. The reactions of B with serum greatly enhanced its propensity to be converted to Cr(VI) by biological oxidants (H2O2 or glucose oxidase system), which is proposed to be a major cause of both the insulin-enhancing activity and toxicity of Cr(III) compounds (Mulyani, I.; Levina, A.; Lay, P. A. Angew. Chem. Int. Ed. 2004, 43, 4504-4507). This finding enhances the current concern over the safety of consumption of large doses of Cr(III) supplements, particularly [Cr(pic)3].

  11. Spectroscopic characterization approach to study surfactants effect on ZnO 2 nanoparticles synthesis by laser ablation process

    NASA Astrophysics Data System (ADS)

    Drmosh, Q. A.; Gondal, M. A.; Yamani, Z. H.; Saleh, T. A.

    2010-05-01

    Zinc peroxide nanoparticles having grain size less than 5 nm were synthesized using pulsed laser ablation in aqueous solution in the presence of different surfactants and solid zinc target in 3% H 2O 2. The effect of surfactants on the optical and structure of ZnO 2 was studied by applying different spectroscopic techniques. Structural properties and grain size of the synthesized nanoparticles were studied using XRD method. The presence of the cubic phase of zinc peroxide in all samples was confirmed with XRD, and the grain sizes were 4.7, 3.7, 3.3 and 2.8 nm in pure H 2O 2, and H 2O 2 mixed with SDS, CTAB and OGM respectively. For optical characterization, FTIR transmittance spectra of ZnO 2 nanoparticles prepared with and without surfactants show a characteristic ZnO 2 absorption at 435-445 cm -1. FTIR spectrum revealed that the adsorbed surfactants on zinc peroxide disappeared in case of CTAB and OGM while it appears in case of SDS. This could be due to high critical micelles SDS concentration comparing with others which is attributed to the adsorption anionic nature of this surfactant. Both FTIR and UV-vis spectra show a red shift in the presence of SDS and blue shift in the presence of CTAB and OGM. The blue shift in the absorption edge indicates the quantum confinement property of nanoparticles. The zinc peroxide nanoparticles prepared in additives-free media was also characterized by Raman spectra which show the characteristic peaks at 830-840 and 420-440 cm -1.

  12. Spectroscopic and laser characterization of emerald. Final report, April 1983-April 1986

    SciTech Connect

    Lai, S.T.; Chai, B.H.

    1986-08-01

    The spectroscopic characteristics and laser properties of emerald were investigated. The laser measurements showed that the emerald-laser tuning range was 720-842 nm and exhibited a high gain and high efficiency in the 760-790 nm range. Under a crystal growth development program, the laser loss was reduced from 11%/cm to 0.4%/cm. The limiting factor in the laser efficiency is the excited-state absorption (ESA). The ESA was measured by two methods: a laser-pumped single-pass gain method, which is generally applicable to all tunable laser materials, and a laser-pumped laser method. A 76% laser quantum yield was obtained in high-optical-quality emerald. The maximum yield is estimated to be 83%, based on the ESA measurements.

  13. Absorption

    PubMed Central

    Menzies, Victoria; Taylor, Ann Gill; Bourguignon, Cheryl

    2009-01-01

    Given that mindbody interventions constitute a major portion of complementary and alternative medicine used by the public, it seems important to explore those human characteristics that may contribute to the efficacy of mindbody interventions in those who are most likely to benefit. One such characteristic, absorption, reflects an individuals cognitive capacity for involvement in sensory and imaginative experiences in ways that alter an individuals perception, memory, and mood with behavioral and biological consequences. Thus, ones level of absorption may potentially create differential treatment effects in mindbody intervention outcomes. Conducting practical clinical trials helps address the challenge of determining whether a specific mindbody modality intervention may be effective. Such trials may be strengthened by including measures of personality dimensions such as absorption. PMID:19126883

  14. Spectroscopic characterization of biological agents using FTIR, normal Raman and surface-enhanced Raman spectroscopies

    NASA Astrophysics Data System (ADS)

    Luna-Pineda, Tatiana; Soto-Feliciano, Kristina; De La Cruz-Montoya, Edwin; Pacheco Londoño, Leonardo C.; Ríos-Velázquez, Carlos; Hernández-Rivera, Samuel P.

    2007-04-01

    FTIR, Raman spectroscopy and Surface Enhanced Raman Scattering (SERS) requires a minimum of sample allows fast identification of microorganisms. The use of this technique for characterizing the spectroscopic signatures of these agents and their stimulants has recently gained considerable attention due to the fact that these techniques can be easily adapted for standoff detection from considerable distances. The techniques also show high sensitivity and selectivity and offer near real time detection duty cycles. This research focuses in laying the grounds for the spectroscopic differentiation of Staphylococcus spp., Pseudomonas spp., Bacillus spp., Salmonella spp., Enterobacter aerogenes, Proteus mirabilis, Klebsiella pneumoniae, and E. coli, together with identification of their subspecies. In order to achieve the proponed objective, protocols to handle, cultivate and analyze the strains have been developed. Spectroscopic similarities and marked differences have been found for Spontaneous or Normal Raman spectra and for SERS using silver nanoparticles have been found. The use of principal component analysis (PCA), discriminate factor analysis (DFA) and a cluster analysis were used to evaluate the efficacy of identifying potential threat bacterial from their spectra collected on single bacteria. The DFA from the bacteria Raman spectra show a little discrimination between the diverse bacterial species however the results obtained from the SERS demonstrate to be high discrimination technique. The spectroscopic study will be extended to examine the spores produced by selected strains since these are more prone to be used as Biological Warfare Agents due to their increased mobility and possibility of airborne transport. Micro infrared spectroscopy as well as fiber coupled FTIR will also be used as possible sensors of target compounds.

  15. Analytical and spectroscopic characterization of humic acids extracted from sewage sludge, manure, and worm compost

    SciTech Connect

    Deiana, S.; Gessa, C.; Manunza, B.; Seeber, R. ); Rausa, R. )

    1990-07-01

    Humic acids extracted from sewage sludges, manure, and worm compost have been characterized by chemical and spectroscopic methods. Meaningful differences in the composition were revealed by FTIR, {sup 1}H, {sup 13}C NMR, and visible spectroscopies. These differences allow a differentiation among the products depending on the source from which they were obtained. Humic acid extracted from sewage sludges contains the highest percentage of aliphatic carbon, associated with polysaccharides and proteinaceous structures, and has characteristics close to those of aquatic humic acids. On the other hand, humic acids from manure and worm compost are similar to the humic acids originating from soil.

  16. Processing of High Level Waste: Spectroscopic Characterization of Redox Reactions in Supercritical Water - Final Report

    SciTech Connect

    Arrington Jr., C. A.

    2000-11-15

    Current efforts are focused on the oxidative dissolution of chromium compounds found in Hanford tank waste sludge. Samples of chromium oxides and hydroxides with varying degrees of hydration are being characterized using Raman, FTIR, and XPS spectroscopic techniques. Kinetics of oxidation reactions at subcritical and supercritical temperatures are being followed by Raman spectroscopy using a high temperature stainless steel cell with diamond windows. In these reactions both hydrogen peroxide and nitrate anions are used as the oxidizing species with Cr(III) compounds and organic compounds as reducing agents.

  17. Characterization of non-Fickian moisture absorption in thermosetting polymers

    NASA Astrophysics Data System (ADS)

    Guloglu, Gorkem E.; Altan, M. Cengiz

    2015-05-01

    A recently developed moisture absorption model for thermosetting polymers that combines the non-Fickian, diffusion hindrance effects and three-dimensional anisotropy is introduced. The hindered diffusion model is shown to predict both short term Fickian and long term anomalous moisture absorption behavior often observed in thermosetting polymers and their composites. The salient characteristics of long term moisture uptake such as the equilibrium moisture content and the effect of non-Fickian phenomena are presented. Anomalous moisture concentration profiles predicted by the two-dimensional solution of hindered diffusion model are demonstrated for various cases, including the through-the-thickness moisture profile of a 40-ply, quartz/bismaleimide (BMI) composite laminate. The effects of diffusion hindrance and anisotropy on the two-dimensional, through-the-thickness concentration profiles are illustrated. The moisture absorption parameters for an EPON 862 epoxy laminate are recovered from the experimental moisture absorption data. The hindered diffusion model is shown to accurately predict the moisture uptake of EPON 862 over the complete absorption time period. The non-Fickian effects governed by the hindrance coefficient are identified for both EPON 862 and quartz/BMI composite laminate. It is shown that the quartz/BMI laminate displays significant non-Fickian behavior compared to EPON 862 epoxy resin.

  18. Structure and spectroscopic characterization of tetrathia- and tetraselena[8]circulenes as a new class of polyaromatic heterocycles.

    PubMed

    Minaeva, Valentina A; Baryshnikov, Gleb V; Minaev, Boris F; Karaush, Nataliya N; Xiong, Xiao-Dong; Li, Ming-De; Phillips, David Lee; Wong, Henry N C

    2015-12-01

    The FTIR, Raman and UV-vis spectra of the recently synthesized tetrathia[8]circulene and tetraselena[8]circulene compounds have been measured and interpreted in details by the density functional theory (DFT) calculations taking into account the molecular symmetry constrains. The structural and electronic features of the studied compounds have also been discussed in connection with the observed spectroscopic characteristics. Particularly, we have found that despite a slightly non-planar conformation the neutral tetrathia[8]circulene and tetraselena[8]circulene molecules demonstrate bifacial aromatic/antiaromatic nature. The inner octatetraene core is characterized by the presence of paratropic ("antiaromatic") ring currents, whereas the outer macrocycle constructed of benzene, thiophene or selenophene rings possesses the strong magnetically-induced diatropic ("aromatic") ring current. This fact suggests the general electronic and magnetic similarity of the tetrathia- and tetraselena[8]circulenes with the strictly planar isoelectronic tetraoxa[8]circulene and related azaoxa-derivatives discussed earlier. However, the vibrational and UV-vis absorption spectra of the studied circulenes are rather different from those of the parent tetraoxa[8]circulene which indicates a clear manifestation of the symmetry selection rules. PMID:26142658

  19. Synthesis, structural characterization, Hirshfeld surface analysis and spectroscopic studies of cadmium (II) chloride complex with 4-hydroxy-1-methylpiperidine

    NASA Astrophysics Data System (ADS)

    Soudani, S.; Ferretti, V.; Jelsch, C.; Lefebvre, F.; Nasr, C. Ben

    2016-05-01

    The chemical preparation, crystal structure, Hirshfeld surface analysis and spectroscopic characterization of the novel cadmium (II) 4-hydroxy-1-methylpiperidine complex, Cd4Cl10(C6H14NO)22H2O, have been reported. The atomic arrangement can be described as built up by an anionic framework, formed by edge sharing CdCl6 and CdCl5O octahedral linear chains spreading along the a-axis. These chains are interconnected by water molecules via O-H⋯Cl and O-H⋯O hydrogen bonds to form layers parallel to (011) plane. The organic cations are inserted between layers through C-H⋯Cl hydrogen bonds. Investigation of intermolecular interactions and crystal packing via Hirshfeld surface analysis reveals that the HC⋯Cl and HC⋯HC intermolecular interactions are the most abundant contacts of the organic cation in the crystal packing. The statistical analysis of crystal contacts reveals the driving forces in the packing formation. The 13C and 15N CP-MAS NMR spectra are in agreement with the X-ray structure. The vibrational absorption bands were identified by infrared spectroscopy. DFT calculations allowed the attribution of the NMR peaks and of the IR bands.

  20. Silver sulfadoxinate: Synthesis, structural and spectroscopic characterizations, and preliminary antibacterial assays in vitro

    NASA Astrophysics Data System (ADS)

    Zanvettor, Nina T.; Abbehausen, Camilla; Lustri, Wilton R.; Cuin, Alexandre; Masciocchi, Norberto; Corbi, Pedro P.

    2015-02-01

    The sulfa drug sulfadoxine (SFX) reacted with Ag+ ions in aqueous solution, affording a new silver(I) complex (AgSFX), which was fully characterized by chemical, spectroscopic and structural methods. Elemental, ESI-TOF mass spectrometric and thermal analyses of AgSFX suggested a [Ag(C12H13N4O2S)] empirical formula. Infrared spectroscopic measurements indicated ligand coordination to Ag(I) through the nitrogen atoms of the (deprotonated) sulfonamide group and by the pyrimidine ring, as well as through oxygen atom(s) of the sulfonamide group. These hypotheses were corroborated by 13C and 15N SS-NMR spectroscopy and by an unconventional structural characterization based on X-ray powder diffraction data. The latter showed that AgSFX crystallizes as centrosymmetric dimers with a strong Ag⋯Ag interaction of 2.7435(6) Å, induced by the presence of exo-bidentate N,N‧ bridging ligands and the formation of an eight-membered ring of [AgNCN]2 sequence, nearly planar. Participation of oxygen atoms of the sulfonamide residues generates in the crystal a 1D coordination polymer, likely responsible for its very limited solubility in all common solvents. Besides the analytical, spectroscopic and structural description, the antibacterial properties of AgSFX were assayed using disc diffusion methods against Escherichia coli and Pseudomonas aeruginosa (Gram-negative), and Staphylococcus aureus (Gram-positive) bacterial strains. The AgSFX complex showed to be active against Gram-positive and Gram-negative bacterial strains, being comparable to the activities of silver sulfadiazine.

  1. Spectroscopic characterization of 2-amino-N-hexadecyl-benzamide (AHBA), a new fluorescence probe for membranes.

    PubMed

    Marquezin, Cássia Alessandra; Hirata, Izaura Yoshico; Juliano, Luiz; Ito, Amando Siuiti

    2006-11-20

    We report the results of investigation on the spectroscopic properties of a new fluorescent lipophylic probe. The fluorophore o-aminobenzoic acid was covalently bound to the acyl chain hexadecylamine, producing the compound 2-amino-N-hexadecyl-benzamide. The behavior of the probe was dependent on the polarity of the medium: absorption and emission spectral position, quantum yield and lifetime decay indicate distinct behavior in water compared to ethanol and cyclohexane. The probe dissolves in the organic solvents, as indicated by the very low value of steady state fluorescence anisotropy and the short rotational correlation times obtained from fluorescence anisotropy decay measurements. On the other hand, the probe has low solubility in water, leading to the formation of aggregates in aqueous medium. The complex absorption spectrum in water was interpreted as originating from different forms of aggregation, as deduced from the wavelength dependence of anisotropy parameters. The probe interacts with surfactants in pre-micellar and micellar forms, as observed in experiments in the presence of sodium n-dodecylsulphate (SDS), n-cetyltrimethylammonium bromide (CTAB); 3-(dodecyl-dimethylammonium) propane-1-sulphonate (DPS) and 3-(hexadecyl-dimethylammonium) propane-1-sulphonate (HPS), and with vesicles of the phospholipid dimiristoyl-phosphatidylcholine (DMPC). The results demonstrate that AHBA is able to monitor properties like surface electric potential and phase transition of micelles and vesicles. PMID:16831508

  2. A nearly on-axis spectroscopic system for simultaneouslymeasuring UV-visible absorption and X-ray diffraction in the SPring-8 structural genomics beamline.

    PubMed

    Sakaguchi, Miyuki; Kimura, Tetsunari; Nishida, Takuma; Tosha, Takehiko; Sugimoto, Hiroshi; Yamaguchi, Yoshihiro; Yanagisawa, Sachiko; Ueno, Go; Murakami, Hironori; Ago, Hideo; Yamamoto, Masaki; Ogura, Takashi; Shiro, Yoshitsugu; Kubo, Minoru

    2016-01-01

    UV-visible absorption spectroscopy is useful for probing the electronic and structural changes of protein active sites, and thus the on-line combination of X-ray diffraction and spectroscopic analysis is increasingly being applied. Herein, a novel absorption spectrometer was developed at SPring-8 BL26B2 with a nearly on-axis geometry between the X-ray and optical axes. A small prism mirror was placed near the X-ray beamstop to pass the light only 2 off the X-ray beam, enabling spectroscopic analysis of the X-ray-exposed volume of a crystal during X-ray diffraction data collection. The spectrometer was applied to NO reductase, a heme enzyme that catalyzes NO reduction to N2O. Radiation damage to the heme was monitored in real time during X-ray irradiation by evaluating the absorption spectral changes. Moreover, NO binding to the heme was probed via caged NO photolysis with UV light, demonstrating the extended capability of the spectrometer for intermediate analysis. PMID:26698082

  3. Quantitative Ultrasound Spectroscopic Imaging for Characterization of Disease Extent in Prostate Cancer Patients1

    PubMed Central

    Sadeghi-Naini, Ali; Sofroni, Ervis; Papanicolau, Naum; Falou, Omar; Sugar, Linda; Morton, Gerard; Yaffe, Martin J.; Nam, Robert; Sadeghian, Alireza; Kolios, Michael C.; Chung, Hans T.; Czarnota, Gregory J.

    2015-01-01

    Three-dimensional quantitative ultrasound spectroscopic imaging of prostate was investigated clinically for the noninvasive detection and extent characterization of disease in cancer patients and compared to whole-mount, whole-gland histopathology of radical prostatectomy specimens. Fifteen patients with prostate cancer underwent a volumetric transrectal ultrasound scan before radical prostatectomy. Conventional-frequency (~5MHz) ultrasound images and radiofrequency data were collected from patients. Normalized power spectra were used as the basis of quantitative ultrasound spectroscopy. Specifically, color-coded parametric maps of 0-MHz intercept, midband fit, and spectral slope were computed and used to characterize prostate tissue in ultrasound images. Areas of cancer were identified in whole-mount histopathology specimens, and disease extent was correlated to that estimated from quantitative ultrasound parametric images. Midband fit and 0-MHz intercept parameters were found to be best associated with the presence of disease as located on histopathology whole-mount sections. Obtained results indicated a correlation between disease extent estimated noninvasively based on midband fit parametric images and that identified histopathologically on prostatectomy specimens, with an r2 value of 0.71 (P<.0001). The 0-MHz intercept parameter demonstrated a lower level of correlation with histopathology. Spectral slope parametric maps offered no discrimination of disease. Multiple regression analysis produced a hybrid disease characterization model (r2=0.764, P<.05), implying that the midband fit biomarker had the greatest correlation with the histopathologic extent of disease. This work demonstrates that quantitative ultrasound spectroscopic imaging can be used for detecting prostate cancer and characterizing disease extent noninvasively, with corresponding gross three-dimensional histopathologic correlation. PMID:25749174

  4. DFT assessment of the spectroscopic constants and absorption spectra of neutral and charged diatomic species of group 11 and 14 elements.

    PubMed

    Tsipis, Athanassios C

    2014-09-15

    The spectroscopic constants and absorption spectra of neutral and charged diatomic molecules of group 11 and 14 elements formulated as [M(2)](+/0/-) (M = Cu, Ag, Au), and [E(2)](+/0/-) (E = C, Si, Ge, Sn, Pb) have been calculated at the PBE0/Def2-QZVPP level of theory. The electronic and bonding properties of the diatomics have been analyzed by natural bond orbital analysis approach and topology analysis by the atoms in molecules method. Particular emphasis was given on the absorption spectra of the diatomic species, which were simulated by time-dependent density functional theory calculations employing the hybrid Coulomb-attenuating CAM-B3LYP density functional. The simulated absorption spectra of the [M(2)](+/0/-) (M = Cu, Ag, Au) and [E(2)](+/0/-) (E = C, Si, Ge, Sn, Pb) species are in close resemblance with the experimentally observed spectra whenever available. The neutral M(2) and E(2) diatomics strongly absorb in the ultraviolet region, given rise to UVC, UVA and in a few cases UVB absorptions. In a few cases, weak absorbion bands also occur in the visible region. The absorption bands have thoroughly been analyzed and assignments of the contributing principal electronic transitions associated to individual excitations have been made. PMID:25043630

  5. Attempted Isolation, Spectroscopic Characterization, and Computational Study of Diazirinone (N2CO), its Analogs, and their Precursors

    NASA Astrophysics Data System (ADS)

    Esselman, Brian J.; Nolan, Alex M.; Amberger, Brent K.; Shaffer, Chris J.; Woods, R. Claude; Stanton, John F.; McMahon, Robert J.

    2010-11-01

    Intrigued by the 2005 reported synthesis of diazirinone, we carried out further experimental and theoretical studies aimed at the detailed matrix-isolation and millimeter-wave spectroscopic characterizations. Diazirinone is a peculiar isoconjugate of two very stable molecules, CO and N2, which may be of astrochemical interest. Unfortunately, the previous reported methods of diazirinone generation did not yield this species, but rather its decomposition products. Encouraged by the many computational studies of the N2CO potential energy surface that all found diazirinone to be the lowest energy isomer, save its decomposition products, we proposed a new method of preparation of diazirinone from the photolysis or thermolysis of carbonyl diazide by loss of two nitrogen molecules. We were able to generate the highly explosive carbonyl diazide in sufficient yield from the reaction of triphosgene and sodium azide. This has allowed us to obtain a matrix-isolation and gas phase IR spectrum of carbonyl diazide which has a gas-phase lifetime of several days. We are currently engaged in the safe purification and distillation of our sample and obtaining a millimeter-wave spectrum of carbonyl diazide. We will attempt to photolyze or thermolyze this molecule to release diazirinone and characterize it by millimeter-wave spectroscopy to pave the way for possible astrochemical detection. In order to provide better mechanistic insight into the decomposition of carbonyl diazide to diazirinone, we have engaged in a DFT and ab initio computational study of several possible pathways. Our preliminary results suggest that of the pathways studied, a step-wise process in which an acyclic CON4 species is generated by loss of nitrogen followed by possible rearrangement and further loss of N2 is most likely. These results will be compared to the analogous reactions for azirinone (HC2NO), our next likely synthetic and spectroscopic target. The millimeter-wave absorption spectrometer used in this research project has been used previously for the investigation of numerous small inorganic molecules and ions. The apparatus consists of a three-meter Pyrex discharge chamber with cylindrical electrodes at each end. The discharge operates at mTorr pressures and at temperatures as low as 77 K. The microwave signal is generated by a Gunn-diode microwave source, which is then further amplified and multiplied to reach the desired frequencies. The signal is focused onto a liquid-helium-cooled indium antimonide detector.

  6. Quantitative characterization of energy absorption in femtosecond laser micro-modification of fused silica.

    PubMed

    Dostovalov, A V; Wolf, A A; Mezentsev, V K; Okhrimchuk, A G; Babin, S A

    2015-12-14

    We present the results of experimental and theoretical study of an energy absorption of femtosecond laser pulse in fused silica. Fundamental and second harmonics of ytterbium laser were used in experiment while general case was considered theoretically and numerically. More efficient absorption at the second harmonics is confirmed both experimentally and numerically. Quantitative characterization of the theoretical model is performed by fitting key parameters of the absorption process such as cross-section of multi-photon absorption and effective electronic collision and recombination times. PMID:26699043

  7. Spectroscopic characterization of 250-?m-selected hyper-luminous star-forming galaxies

    NASA Astrophysics Data System (ADS)

    Casey, C. M.; Chapman, S. C.; Smail, Ian; Alaghband-Zadeh, S.; Bothwell, M. S.; Swinbank, A. M.

    2011-03-01

    We present near-infrared (near-IR) spectroscopic observations from Very Large Telescope Infrared Spectrometer And Array Camera (ISAAC) of 13 250-?m luminous galaxies in the Chandra Deep Field-South, seven of which have confirmed redshifts which average to = 2.0 0.4. Another two sources of the 13 have tentative z > 1 identifications. Eight of the nine redshifts were identified with H? detection in H and K bands, three of which are confirmed redshifts from previous spectroscopic surveys. We use their near-IR spectra to measure H? linewidths and luminosities, which average to 415 20 km s-1 and 3 1035 W (implying SFR H? 200 M ? yr-1), both similar to the H? properties of submillimetre galaxies (SMGs). Just like SMGs, 250-?m-luminous galaxies have large H? to far-infrared (FIR) extinction factors such that the H? star formation rates (SFRs) underestimate the FIR SFRs by approximately eight to 80 times. FIR photometric points observed from 24 to 870 ?m are used to constrain the spectral energy distributions even though uncertainty caused by FIR confusion in the Balloon-borne Large-Aperture Submillimeter Telescope (BLAST) bands is significant. The population has a mean dust temperature of Td= 52 6 K, emissivity ?= 1.73 0.13 and FIR luminosity LFIR= 3 1013 L?. Although selection at 250 ?m allows for the detection of much hotter dust-dominated hyper-luminous infrared galaxies (HyLIRGs) than SMG selection (at 850 ?m), we do not find any ?60-K 'hot-dust' HyLIRGs. We have shown that near-IR spectroscopy combined with good photometric redshifts is an efficient way to spectroscopically identify and characterize these rare, extreme systems, hundreds of which are being discovered by the newest generation of IR observatories including the Herschel Space Observatory.

  8. Comparison of the characterization on binding of alpinetin and cardamonin to lysozyme by spectroscopic methods.

    PubMed

    He, Wenying; Li, Ying; Tang, Jianghong; Luan, Feng; Jin, Jing; Hu, Zhide

    2006-11-15

    Studies on the binding affinity of protein to the active components of herbs are novel in biochemistry and are valuable for the information about speciation of drugs and exchange in biological systems. Alpinetin and cardamonin, two of the main constituents from the seeds of Alpinia katsumadai Hayata, have been used in traditional herbs as antibacterial, anti-inflammatory, and other important therapeutic activities of significant potency and low systemic toxicity. The interactions between two flavonoids analogs and lysozyme have been studied for the first time by spectroscopic method including Fourier transform infrared (FT-IR) spectroscopy, circular dichroism (CD) and UV-absorption spectroscopy in combination with Fluorescence quenching study. Both molecules showed high affinities to lysozyme under the experimental condition with drug concentrations from 3.33 x 10(-6) to 2.67 x 10(-5)molL(-1) for alpinetin and 1.67 x 10(-6) to 13.33 x 10(-6)molL(-1) for cardamonin. The alterations of protein secondary structure in the presence of drugs in aqueous solution were quantitatively estimated by the evidences from CD and FT-IR spectroscopy. The thermodynamic parameters obtained and the results of spectroscopic measurements suggest that hydrophobic and electrostatic interactions are the predominant intermolecular forces stabilizing two coordination compounds. The quenching mechanism and the number of binding site (n approximately 1) were obtained by fluorescence titration data. The efficiency of energy transfer provided the binding distances of 4.04 and 5.90 nm for alpinetin-LYSO and cardamonin-LYSO systems, respectively. PMID:16828496

  9. Chemical and spectroscopic characterization of a suite of Mars soil analogs

    NASA Technical Reports Server (NTRS)

    Coyne, L. M.; Banin, A.; Orenberg, J. B.; Carle, G. C.; Chang, S.; Scattergood, T. W.

    1987-01-01

    The National Aeronautics and Space Administration has begun preparations for the flight of the Mars Observer Mission in the early 1990s. An advanced ground-based study is being conducted on a usefully limited suite of Mars Soil Analog Materials (MarSAM) intended to simulate the aeolian material covering the surface of Mars. A series of variably proportioned iron/calcium smectite clays were prepared from a typical montmorillonite clay using the Banin method. The effect of increasing iron on a diverse set of chemical and spectroscopic properties of the suite of clays is discussed. In order to chemically characterize the MarSAM and compare them with the Martian soil studied by Viking, the clays were analyzed for their major and minor elemental compositions by X-ray fluorescence and ion-coupled plasma techniques. It was concluded that the surface iron has a complex and hitherto uninvestigated impact on the catalytic and spectroscopic properties of clays and on the ability of these material to store energy.

  10. Chemical and spectroscopic characterization of a suite of Mars soil analogs

    NASA Astrophysics Data System (ADS)

    Coyne, L. M.; Banin, A.; Orenberg, J. B.; Carle, G. C.; Chang, S.; Scattergood, T. W.

    The National Aeronautics and Space Administration has begun preparations for the flight of the Mars Observer Mission in the early 1990s. An advanced ground-based study is being conducted on a usefully limited suite of Mars Soil Analog Materials (MarSAM) intended to simulate the aeolian material covering the surface of Mars. A series of variably proportioned iron/calcium smectite clays were prepared from a typical montmorillonite clay using the Banin method. The effect of increasing iron on a diverse set of chemical and spectroscopic properties of the suite of clays is discussed. In order to chemically characterize the MarSAM and compare them with the Martian soil studied by Viking, the clays were analyzed for their major and minor elemental compositions by X-ray fluorescence and ion-coupled plasma techniques. It was concluded that the surface iron has a complex and hitherto uninvestigated impact on the catalytic and spectroscopic properties of clays and on the ability of these material to store energy.

  11. FT-IR spectroscopic, thermal analysis of human urinary stones and their characterization

    NASA Astrophysics Data System (ADS)

    Selvaraju, R.; Raja, A.; Thiruppathi, G.

    2015-02-01

    In the present study, FT-IR, XRD, TGA-DTA spectral methods have been used to investigate the chemical compositions of urinary calculi. Multi-components of urinary calculi such as calcium oxalate, hydroxyl apatite, struvite and uric acid have been studied. The chemical compounds are identified by FT-IR spectroscopic technique. The mineral identification was confirmed by powder X-ray diffraction patterns as compared with JCPDS reported values. Thermal analysis techniques are considered the best techniques for the characterization and detection of endothermic and exothermic behaviors of the urinary stones. The percentages of each hydrate (COM and COD) are present together, in the presences of MAPH or UA. Finally, the present study suggests that the Urolithiasis is significant health problem in children, and is very common in some parts of the world, especially in India. So that present study is so useful and helpful to the scientific community for identification of latest human health problems and their remedies using spectroscopic techniques.

  12. FT-IR spectroscopic, thermal analysis of human urinary stones and their characterization.

    PubMed

    Selvaraju, R; Raja, A; Thiruppathi, G

    2015-02-25

    In the present study, FT-IR, XRD, TGA-DTA spectral methods have been used to investigate the chemical compositions of urinary calculi. Multi-components of urinary calculi such as calcium oxalate, hydroxyl apatite, struvite and uric acid have been studied. The chemical compounds are identified by FT-IR spectroscopic technique. The mineral identification was confirmed by powder X-ray diffraction patterns as compared with JCPDS reported values. Thermal analysis techniques are considered the best techniques for the characterization and detection of endothermic and exothermic behaviors of the urinary stones. The percentages of each hydrate (COM and COD) are present together, in the presences of MAPH or UA. Finally, the present study suggests that the Urolithiasis is significant health problem in children, and is very common in some parts of the world, especially in India. So that present study is so useful and helpful to the scientific community for identification of latest human health problems and their remedies using spectroscopic techniques. PMID:25306135

  13. Characterization of High Ge Content SiGe Heterostructures and Graded Alloy Layers Using Spectroscopic Ellipsometry

    NASA Technical Reports Server (NTRS)

    Heyd, A. R.; Alterovitz, S. A.; Croke, E. T.

    1995-01-01

    Si(x)Ge(1-x)heterostructures on Si substrates have been widely studied due to the maturity of Si technology. However, work on Si(x)Ge)1-x) heterostructures on Ge substrates has not received much attention. A Si(x)Ge(1-x) layer on a Si substrate is under compressive strain while Si(x)Ge(1-x) on Ge is under tensile strain; thus the critical points will behave differently. In order to accurately characterize high Ge content Si(x)Ge(1-x) layers the energy shift algorithm used to calculate alloy compositions, has been modified. These results have been used along with variable angle spectroscopic ellipsometry (VASE) measurements to characterize Si(x)Ge(1-x)/Ge superlattices grown on Ge substrates. The results agree closely with high resolution x-ray diffraction measurements made on the same samples. The modified energy shift algorithm also allows the VASE analysis to be upgraded in order to characterize linearly graded layers. In this work VASE has been used to characterize graded Si(x)Ge(1-x) layers in terms of the total thickness, and the start and end alloy composition. Results are presented for a 1 micrometer Si(x)Ge(1-x) layer linearly graded in the range 0.5 less than or equal to x less than or equal to 1.0.

  14. Optical characterization of ferroelectric PZT thin films by variable angle spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Rahman, Md. Shafiqur; Garcia, Carlos D.; Bhalla, Amar; Guo, Ruyan

    2014-09-01

    Ferroelectric thin films are used as high dielectric constant capacitors, infrared detectors, piezoelectric transducers, optical modulators, optical waveguides, and nonvolatile memory chips for dynamic random access memory (DRAM) etc. While ferroelectric and dielectric properties of these films have been extensively investigated, their optical properties have been comparatively less studied and of limited use in quantitative evaluation of multilayer thin films. In this work we explored the variable angle spectroscopic ellipsometry (VASE) technique for its effectiveness in physical property characterization. The VASE combined with its computer modeling tool enables nondestructive, nonintrusive, and contactless optical means for optical characterization. Crystalline Lead Zirconium Titanate PbZr0.52Ti0.48O3 (PZT) thin films, fabricated on SrTiO3 layer atop of Si substrates, were characterized using VASE (J.A. Woollam; Lincoln, NE, USA) by determining the ellipsometric parameters ? and ? as a function of wavelengths (200-1000 nm) and incident angles (65, 70,75) at room temperature. A physical representation of the multilayer system was constructed by a six layer model (analysis software WVASE32, J.A. Woollam) through a step-by-step method. Other physical properties characterized by several well-known techniques on structure, morphology and topographical features correspond well with the models developed using VASE alone. The technique and the methodology developed have shown promises in identifying the respective thickness and optical properties of multilayer thin film system, with limited input of processing or composition information.

  15. Characterization of Spectral Absorption Properties of Aerosols Using Satellite Observations

    NASA Technical Reports Server (NTRS)

    Torres, O.; Jethva, H.; Bhartia, P. K.; Ahn, C.

    2012-01-01

    The wavelength-dependence of aerosol absorption optical depth (AAOD) is generally represented in terms of the Angstrom Absorption Exponent (AAE), a parameter that describes the dependence of AAOD with wavelength. The AAE parameter is closely related to aerosol composition. Black carbon (BC) containing aerosols yield AAE values near unity whereas Organic carbon (OC) aerosol particles are associated with values larger than 2. Even larger AAE values have been reported for desert dust aerosol particles. Knowledge of spectral AAOD is necessary for the calculation of direct radiative forcing effect of aerosols and for inferring aerosol composition. We have developed a satellitebased method of determining the spectral AAOD of absorbing aerosols. The technique uses high spectral resolution measurements of upwelling radiation from scenes where absorbing aerosols lie above clouds as indicated by the UV Aerosol Index. For those conditions, the satellite measured reflectance (rho lambda) is approximately given by Beer's law rho lambda = rho (sub 0 lambda) e (exp -mtau (sub abs lambda)) where rho(sub 0 lambda) is the cloud reflectance, m is the geometric slant path and tau (sub abs lambda) is the spectral AAOD. The rho (sub 0 lambda) term is determined by means of radiative transfer calculations using as input the cloud optical depth derived as described in Torres et al. [JAS, 2012] that accounts for the effects of aerosol absorption. In the second step, corrections for molecular and aerosol scattering effects are applied to the cloud reflectance term, and the spectral AAOD is then derived by inverting the equation above. The proposed technique will be discussed in detail and application results will be presented. The technique can be easily applied to hyper-spectral satellite measurements that include UV such as OMI, GOME and SCIAMACHY, or to multi-spectral visible measurements by other sensors provided that the aerosol-above-cloud events are easily identified.

  16. The synthesis and spectroscopic characterization of nano calcium fluorapatite using tetra-butylammonium fluoride.

    PubMed

    Sheykhan, Mehdi; Heydari, Akbar; Ma'mani, Leila; Badiei, Alireza

    2011-12-01

    Pure homogeneous nano sized biocompatible fluorapatite (FAp) particles were synthesized by a wet chemical procedure using water soluble tetra-butylammonium fluoride (TBAF) without using high temperatures and any purification processes. Combination of the Bragg's law and the plane-spacing equation for the two high intensity lines, namely, (002) and (300), gives a=9.3531 ?, c=6.8841 ?, confirms the identity of the highly crystalline synthetic material as well as its purity. The effect of various pH's in crystal formation and on their size was also evaluated. The calculated crystallinities were excellent with a rate around 5.0. The synthesized nano FAp was fully characterized by spectroscopic techniques (XRD, SEM, EDS, BET, FT-IR and ICP-AES). The nitrogen adsorption-desorption isotherm showed a type IV diagram and calculation of the surface area was investigated as well. PMID:21930424

  17. The synthesis and spectroscopic characterization of nano calcium fluorapatite using tetra-butylammonium fluoride.

    TOXLINE Toxicology Bibliographic Information

    Sheykhan M; Heydari A; Ma'mani L; Badiei A

    2011-12-01

    Pure homogeneous nano sized biocompatible fluorapatite (FAp) particles were synthesized by a wet chemical procedure using water soluble tetra-butylammonium fluoride (TBAF) without using high temperatures and any purification processes. Combination of the Bragg's law and the plane-spacing equation for the two high intensity lines, namely, (002) and (300), gives a=9.3531 ?, c=6.8841 ?, confirms the identity of the highly crystalline synthetic material as well as its purity. The effect of various pH's in crystal formation and on their size was also evaluated. The calculated crystallinities were excellent with a rate around 5.0. The synthesized nano FAp was fully characterized by spectroscopic techniques (XRD, SEM, EDS, BET, FT-IR and ICP-AES). The nitrogen adsorption-desorption isotherm showed a type IV diagram and calculation of the surface area was investigated as well.

  18. Spectroscopic characterization of recently excavated archaeological potsherds from Tamilnadu, India with multi-analytical approach.

    PubMed

    Raja Annamalai, G; Ravisankar, R; Rajalakshmi, A; Chandrasekaran, A; Rajan, K

    2014-12-10

    A combined analytical study of potsherds excavated from different archaeological sites of Tamilnadu (Kavalapatti, Nattapuraki and Thamaraikulam villages), India are analyzed by spectroscopic techniques such as FTIR, X-ray diffraction, thermogravimetric analysis (TGA) and Scanning Electron Microscope (SEM) coupled with Energy Dispersive Spectrometer (EDS). FTIR and XRD techniques have been attempted to characterize the mineralogical composition, firing temperature and firing conditions of the archaeological potsherds. Thermogravimetric analysis (TGA) is the complementary study to estimate the firing temperature from characteristic thermal reactions in potsherds under controlled firing in inert gas atmosphere. Further, Scanning Electron Microscopy (SEM) equipped and coupled with an Energy Dispersive Spectrometer (EDS) to analyze internal morphology and chemical composition of the potsherds was used. From the results of the above techniques, the firing temperatures of potsherds were found to be greater than 650C. PMID:24929323

  19. Metal ion binding by a bicyclic diamide: Deep UV Raman spectroscopic characterization

    SciTech Connect

    Shashilov, Victor A.; Ermolenkov, Vladimir V.; Levitskaia, Tatiana G.; Lednev, Igor K.

    2005-08-18

    Deep UV resonance Raman spectroscopy was used for characterizing ligand-metal ion complexes. The obtained results demonstrated a strong intrinsic sensitivity and selectivity of a Raman spectroscopic signature of a bicyclic diamide, a novel chelating agent for lanthanides and actinides (Lumetta, G. J.; Rapko, B. M.; Garza, P. A.; Hay, B. P.; Gilbertson, R. D.; Weakley, T. J. R.; Hutchison, J. E. J. Am. Chem. Soc. 2002, 124, 5644). Molecular modeling, which included structure optimization and calculation of Raman frequencies and resonance intensities, allowed for assigning all strong Raman bands of the bicyclic diamide as well as predicting the band shifts observed because of complex formation with metal ions. A comparative analysis of Raman spectra and the results of the molecular modeling could be used for elucidating the structure of complexes in solution.

  20. Zinc acetylacetonate hydrate adducted with nitrogen donor ligands: Synthesis, spectroscopic characterization, and thermal analysis

    NASA Astrophysics Data System (ADS)

    Brahma, Sanjaya; Shivashankar, S. A.

    2015-12-01

    We report synthesis, spectroscopic characterization, and thermal analysis of zinc acetylacetonate complex adducted by nitrogen donor ligands, such as pyridine, bipyridine, and phenanthroline. The pyridine adducted complex crystallizes to monoclinic crystal structure, whereas other two adducted complexes have orthorhombic structure. Addition of nitrogen donor ligands enhances the thermal property of these complexes as that with parent metal-organic complex. Zinc acetylacetonate adducted with pyridine shows much higher volatility (106C), decomposition temperature (202C) as that with zinc acetylacetonate (136C, 220C), and other adducted complexes. All the adducted complexes are thermally stable, highly volatile and are considered to be suitable precursors for metal organic chemical vapor deposition. The formation of these complexes is confirmed by powder X-ray diffraction, Fourier transform infrared spectroscopy, mass spectroscopy, and elemental analysis. The complexes are widely used as starting precursor materials for the synthesis of ZnO nanostructures by microwave irradiation assisted coating process.

  1. Synthesis, spectroscopic characterization and biological analysis of a new palladium(II) complex with methionine sulfoxide

    NASA Astrophysics Data System (ADS)

    Corbi, Pedro P.; Cagnin, Flávia; Sabeh, Lilian P. B.; Massabni, Antonio C.; Costa-Neto, Claudio M.

    2007-04-01

    A new palladium(II) complex with methionine sulfoxide was synthesized and characterized by a set of chemical and spectroscopic techniques. Elemental and mass spectrometry analyses of the solid complex fit to the composition [Pd(C 5H 10NO 3S) 2]·H 2O. 13C NMR, [ 1H- 15N] NMR and infrared spectra indicate coordination of the amino acid to Pd(II) through the carboxylate and amino groups in a square planar geometry. The complex is soluble in water. Biological activity was evaluated by cytotoxic analysis using HeLa cells. Determination of cell death was assessed using a tetrazolium salt colorimetric assay, which reflects the cells viability. After incubation for 48 h, 20% of cell death was achieved at a concentration of 200 μmol L -1 of the complex.

  2. Energy absorption characterization of human enamel using nanoindentation.

    PubMed

    He, Li Hong; Swain, Michael V

    2007-05-01

    Enamel is a natural composite, which has much higher toughness than its major component, crystalline hydroxyapatite. In this study, the energy absorption behavior of human sound enamel was investigated with nanoindentation techniques. A UMIS nanoindenter system as well as a Berkovich and two spherical indenters with nominal tip radii of 5 and 20 microm were used to indent enamel at different loading forces in the direction parallel to enamel prisms. Inelastic energy dissipation versus depth of indenter penetration (U%-h(p) curve) as well as a function of indentation strain (U%-epsilon curve) of enamel was determined. Enamel showed much higher energy absorption capacity than a ceramic material with equivalent modulus (fused silica). Even at the lowest forces (1 mN) for the 20 microm indenter, inelastic response was found. Additional tests done at different force loading rates illustrated that load rate has little influence on P-h response of enamel. The top surface of enamel has the plastic work of indentation of approximately 5.2 nJ/microm(3). The energy absorbing ability is influenced by the very small protein rich component that exists between the hydroxyapatite nanocrystals as well as within the sheath structure surrounding the enamel rods. PMID:17133444

  3. Synthesis and spectroscopic characterization studies of low molecular weight light emitting PPV segmented copolymers

    NASA Astrophysics Data System (ADS)

    Ali, Basil; Jabar, Sattar; Salih, Whidad; Al Tamimi, Raed K.; Al Attar, Hameed; Monkman, Andy P.

    2009-12-01

    New tuneable segmented alternating copoly( p-phenylene vinylene) (PPV) derivatives were chemically synthesised via the Wittig polycondensation reaction. The chemical and optical properties in solution and in solid state were evaluated. The absorption and photoemission spectra show that incorporating an ethane dioxy spacer limits the conjugation length and produces a blue emitting copolymer, poly[1,2-ethane dioxy 2-methoxy-1,4-phenylene-vinyl 1,4-phenylene-vinyl 3-methoxy 1,4-phenylene] (EDO-PPV- 1) 1. A red shift in the copolymer emission was achieved by adding an electron-donating group, a hexoloxy-substituted PPV segment, poly[1,2-ethane dioxy 2-methoxy-1,4-phenylene-vinyl 2,5-dihexoloxy 1,4-phenylene-vinyl 3-methoxy 1,4-phenylene] (EDO-PPV- 2) 2. The photophysical properties of these block copolymers was compared with the fully conjugated copolymer poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) 3. The absorption band of the ? deloc- ?deloc? transition at 400-500 nm is limited in 1 and 2 indicating that the conjugation is effectively interrupted. The effect of torsional motions on the Stokes shift in these segmented copolymers is discussed. The photoluminescence (PL) efficiency and lifetime of 1 and 2 is different, indicating that the contribution from additional non-radiative decay channels due to interchain interactions is significant. The steady state and time-resolved photophysical characteristics of the thin film form of the copolymers indicates a high order of stacking in copolymer 1 and strong interchain interaction leading to strong excimer emission which may be ascribed to the low folding degree and planarity of the copolymers chemical structure. The spectroscopic time-resolved analysis confirms the interchain interaction.

  4. Electrochemical and resonance Raman spectroscopic characterization of polyaniline and polyaniline-metalloporphyrin electrode films

    SciTech Connect

    Macor, K.A.; Su, Y.O.; Miller, L.A.; Spiro, T.G.

    1987-08-12

    Characteristics of electropolymerized aniline and metallotetrakis(2-aminophenyl)porphine (metallo-2-TAPP) films are described. Aniline polymerized from methylene chloride solution by oxidative cycling at a platinum electrode shows characteristic two-wave or one-wave cycle voltammograms when scanned in pH 1 aqueous solution, depending on the positive potential sweep limit. Similar CV's are produced when the solution contains metallo-TAPP's, except that additional waves associated with metalloporphyrin redox processes are superimposed. The absorption spectra of the films formed on transparent SnO/sub 2/ electrodes showed characteristic metalloporphyrin Soret absorption bands, with red shifts relative to the solution spectra, due to axial coordination and/or excitonic effects. Raman spectra are reported for films polymerized from aniline, aniline-/sup 15/N, aniline-N,N-d/sub 2/, and aniline-d/sub 5/. The replacement of strong aniline bands at 1000 and 1029 cm/sup -1/ with bands in the films at 1190 and 1200 cm/sup -1/ is diagnostic for para-substituted aniline units in the polymer. The films show a strong /sup 15/N-sensitive band at 1525 cm/sup -1/, which is absent in aniline but present in p-phenylenediamine. Thus the electrochemical and spectroscopic characteristics of the TAPP films are fully consistent with unmodified porphyrin units contained within a polyaniline polymer. Porphyrin radical cation formation is insufficient to induce polymerization if the potential is lower than that required for aniline oxidation. Films containing Mn(2-TAPP) show a Mn/sup 3+/2+/ wave at approx.-0.2 V, negative of the polyaniline redox waves, when the electrode is in contact with nonaqueous or aqueous electrolyte. The metalloporphyrin redox process does not require electronic conduction through the polyaniline framework. 21 references. 8 figures.

  5. Spectroscopic Characterization of a Green Copper Site in a Single-Domain Cupredoxin

    PubMed Central

    Roger, Magali; Biaso, Frdric; Castelle, Cindy J.; Bauzan, Marielle; Chaspoul, Florence; Lojou, Elisabeth; Sciara, Giuliano; Caffarri, Stefano; Giudici-Orticoni, Marie-Thrse; Ilbert, Marianne

    2014-01-01

    Cupredoxins are widespread copper-binding proteins, mainly involved in electron transfer pathways. They display a typical rigid greek key motif consisting of an eight stranded ?-sandwich. A fascinating feature of cupredoxins is the natural diversity of their copper center geometry. These geometry variations give rise to drastic changes in their color, such as blue, green, red or purple. Based on several spectroscopic and structural analyses, a connection between the geometry of their copper-binding site and their color has been proposed. However, little is known about the relationship between such diversity of copper center geometry in cupredoxins and possible implications for function. This has been difficult to assess, as only a few naturally occurring green and red copper sites have been described so far. We report herein the spectrocopic characterization of a novel kind of single domain cupredoxin of green color, involved in a respiratory pathway of the acidophilic organism Acidithiobacillus ferrooxidans. Biochemical and spectroscopic characterization coupled to bioinformatics analysis reveal the existence of some unusual features for this novel member of the green cupredoxin sub-family. This protein has the highest redox potential reported to date for a green-type cupredoxin. It has a constrained green copper site insensitive to pH or temperature variations. It is a green-type cupredoxin found for the first time in a respiratory pathway. These unique properties might be explained by a region of unknown function never found in other cupredoxins, and by an unusual length of the loop between the second and the fourth copper ligands. These discoveries will impact our knowledge on non-engineered green copper sites, whose involvement in respiratory chains seems more widespread than initially thought. PMID:24932914

  6. Spectroscopic characterizations of Er doped LaPO4 submicron phosphors prepared by homogeneous precipitation method

    NASA Astrophysics Data System (ADS)

    Saltmarsh, N.; Kumar, G. A.; Kailasnath, M.; Shenoy, Vittal; Santhosh, C.; Sardar, D. K.

    2016-03-01

    Hexagonal shaped LaPO4 submicron particles doped with various concentrations of Er were successfully prepared by homogenous precipitation method using metal nitrates and ammonium phosphate. Particles of approximate particle size 125 nm and size distribution of 85 nm are obtained with good crystallinity. After heat treatment at 1200 °C for 2 h, the particles are characterized for their various optical properties such as absorption, emission, fluorescence decay and optical band gap. Optical absorption and emission data are numerically analyzed with the help of Judd-Ofelt model to evaluate various radiative spectral properties such as radiative decay rates, radiative quantum yield, emission cross-section and fluorescence branching ratios of various emission transitions. Though the radiative quantum yield of 1554 nm emission approaches the theoretical limit of 100%, the experimentally measured quantum yield is only 11% at 12 W/cm2 at 980 nm excitation power density in 2% Er doped LaPO4.

  7. Spectroscopic characterization of effective components anthraquinones in Chinese medicinal herbs binding with serum albumins.

    PubMed

    Bi, Shuyun; Song, Daqian; Kan, Yuhe; Xu, Dong; Tian, Yuan; Zhou, Xin; Zhang, Hanqi

    2005-11-01

    The interactions of serum albumins such as human serum albumin (HSA) and bovine serum albumin (BSA) with emodin, rhein, aloe-emodin and aloin were assessed employing fluorescence quenching and absorption spectroscopic techniques. The results obtained revealed that there are relatively strong binding affinity for the four anthraquinones with HSA and BSA and the binding constants for the interactions of anthraquinones with HSA or BSA at 20 degrees C were obtained. Anthraquinone-albumin interactions were studied at different temperatures and in the presence of some metal ions. And the competition binding of anthraquinones with serum albumins was also discussed. The Stern-Volmer curves suggested that the quenching occurring in the reactions was the static quenching process. The binding distances and transfer efficiencies for each binding reactions were calculated according to the Fster theory of non-radiation energy transfer. Using thermodynamic equations, the main action forces of these reactions were also obtained. The reasons of the different binding affinities for different anthraquinone-albumin reactions were probed from the point of view of molecular structures. PMID:16257715

  8. Optical and spectroscopic characterization of Er3+-Yb3+co-doped tellurite glasses and fibers

    NASA Astrophysics Data System (ADS)

    Narro-Garca, R.; Desirena, H.; Chillcce, E. F.; Barbosa, L. C.; Rodriguez, E.; De la Rosa, E.

    2014-04-01

    Optical and spectroscopic properties of Er3+-Yb3+ co-doped TeO2-WO3-Nb2O5-Na2O-Al2O3 glasses and fibers were investigated. Emission spectra and fluorescence lifetimes of 4I13/2 level of Er3+ion as a function of rare earth concentration and fiber length were measured in glasses. Results show that the self-absorption effect broadens the spectral bandwidth of 4I13/2?4I15/2 transition and lengthens the lifetime significantly from 3.5 to 4.6 ms. Fibers were fabricated by the rod-in-tube technique using a Heathway drawing tower. The emission power of these Er3+-Yb3+ co-doped Step Index Tellurite Fibers (SITFs; lengths varying from 2 to 60 cm) were generated by a 980 nm diode laser pump and then the emission power spectra were acquired with an OSA. The maximum emission power spectra, within the 1530-1560 nm region, were observed for fiber lengths ranging from 3 to 6 cm. The highest bandwidth obtained was 108 nm for 8 cm fiber length around 1.53 m.

  9. Spectroscopic characterization of effective components anthraquinones in Chinese medicinal herbs binding with serum albumins

    NASA Astrophysics Data System (ADS)

    Bi, Shuyun; Song, Daqian; Kan, Yuhe; Xu, Dong; Tian, Yuan; Zhou, Xin; Zhang, Hanqi

    2005-11-01

    The interactions of serum albumins such as human serum albumin (HSA) and bovine serum albumin (BSA) with emodin, rhein, aloe-emodin and aloin were assessed employing fluorescence quenching and absorption spectroscopic techniques. The results obtained revealed that there are relatively strong binding affinity for the four anthraquinones with HSA and BSA and the binding constants for the interactions of anthraquinones with HSA or BSA at 20 C were obtained. Anthraquinone-albumin interactions were studied at different temperatures and in the presence of some metal ions. And the competition binding of anthraquinones with serum albumins was also discussed. The Stern-Volmer curves suggested that the quenching occurring in the reactions was the static quenching process. The binding distances and transfer efficiencies for each binding reactions were calculated according to the Fster theory of non-radiation energy transfer. Using thermodynamic equations, the main action forces of these reactions were also obtained. The reasons of the different binding affinities for different anthraquinone-albumin reactions were probed from the point of view of molecular structures.

  10. Synthesis, characterization and spectroscopic behavior of novel 2-oxo-1,4-disubstituted-1,2,5,6-tetrahydrobenzo[h]quinoline-3-carbonitrile dyes

    NASA Astrophysics Data System (ADS)

    Khan, Salman A.; Asiri, Abdullah M.; Al-Thaqafy, Saad H.; Faidallah, Hassan M.; El-Daly, Samy A.

    2014-12-01

    Two synthetic pathways were adopted to synthesize the target 2-oxo-1,4-disubstituted-1,2,5,6-tetrahydro-benzo[h]quinoline-3-carbonitriles. Structure of the synthesized compounds has been characterized based on FT-IR, 1H NMR, 13C NMR and elemental analyses. UV-Vis and fluorescence spectroscopy measurements provided that all compounds are good absorbent and fluorescent. Fluorescence polarity study demonstrated that these compounds were sensitive to the polarity of the microenvironment provided by different solvents. In addition, spectroscopic and physicochemical parameters, including singlet absorption, extinction coefficient, Stokes shift, oscillator strength and dipole moment were investigated in order to explore the analytical potential of synthesized compounds.

  11. Characterization of the oral absorption of several aminopenicillins: determination of intrinsic membrane absorption parameters in the rat intestine in situ

    NASA Technical Reports Server (NTRS)

    Sinko, P. J.; Amidon, G. L.

    1992-01-01

    The absorption mechanism of several penicillins was characterized using in situ single-pass intestinal perfusion in the rat. The intrinsic membrane parameters were determined using a modified boundary layer model (fitted value +/- S.E.): Jmax* = 11.78 +/- 1.88 mM, Km = 15.80 +/- 2.92 mM, Pm* = 0, Pc* = 0.75 +/- 0.04 for ampicillin; Jmax* = 0.044 +/- 0.018 mM, Km = 0.058 +/- 0.026 mM, Pm* = 0.558 +/- 0.051, Pc* = 0.757 +/- 0.088 for amoxicillin; and Jmax* = 16.30 +/- 3.40 mM, Km = 14.00 +/- 3.30 mM, Pm* = 0, Pc* = 1.14 +/- 0.05 for cyclacillin. All of the aminopenicillins studied demonstrated saturable absorption kinetics as indicated by their concentration-dependent wall permeabilities. Inhibition studies were performed to confirm the existence of a nonpassive absorption mechanism. The intrinsic wall permeability (Pw*) of 0.01 mM ampicillin was significantly lowered by 1 mM amoxicillin and the Pw* of 0.01 mM amoxicillin was reduced by 2 mM cephradine consistent with competitive inhibition.

  12. A multi-epoch spectroscopic study of the BAL quasar APM 08279+5255. I. C IV absorption variability

    NASA Astrophysics Data System (ADS)

    Trevese, D.; Saturni, F. G.; Vagnetti, F.; Perna, M.; Paris, D.; Turriziani, S.

    2013-09-01

    Context. Broad absorption lines indicate gas outflows with velocities from thousands of km s-1 to about 0.2 the speed of light, which may be present in all quasars and may play a major role in the evolution of the host galaxy. The variability of absorption patterns can provide information on changes in the density and velocity distributions of the absorbing gas and its ionisation status. Aims: We want to accurately follow the evolution in time of the luminosity and both the broad and narrow C IV absorption features of an individual object, the quasar APM 08279+5255, and analyse the correlations among these quantities. Methods: We have collected 23 photometrical and spectro-photometrical observations at the 1.82 m Telescope of the Asiago Observatory since 2003, plus 5 other spectra from the literature. We analysed the evolution in time of the equivalent width of the broad absorption feature and two narrow absorption systems, the correlation among them and with the R band magnitude. We performed a structure function analysis of the equivalent width variations. Results: We present an unprecedented monitoring of a broad absorption line quasar based on 28 epochs during 14 years. The shape of broad absorption feature shows relative stability, while its equivalent width slowly declines until it sharply increases during 2011. At the same time, the R magnitude stays almost constant until it sharply increases during 2011. The equivalent width of the narrow absorption redwards of the systemic redshift only shows a decline. Conclusions: The broad absorption behaviour suggests changes in the ionisation status as the main cause of variability. We show for the first time a correlation of this variability with the R band flux. The different behaviour of the narrow absorption system might be due to recombination time delay. The structure function of the absorption variability has a slope comparable with typical optical variability of quasars. This is consistent with variations of the 200 ionising flux originating in the inner part of the accretion disk.

  13. Transient Spectroscopic Characterization of the Genesis of a Ruthenium Complex Catalyst Supported on Zeolite Y

    SciTech Connect

    Ogino, Isao; Gates, Bruce C.

    2010-01-12

    A mononuclear ruthenium complex anchored to dealuminated zeolite HY, Ru(acac)(C{sub 2}H{sub 4}){sup 2+} (acac = acetylacetonate, C{sub 5}H{sub 7}O{sup 2}{sup -}), was characterized in flow reactors by transient infrared (IR) spectroscopy and Ru K edge X-ray absorption spectroscopy. The combined results show how the supported complex was converted into a form that catalyzes ethene conversion to butene. The formation of these species resulted from the removal of acac ligands from the ruthenium (as shown by IR and extended X-ray absorption fine structure (EXAFS) spectra) and the simultaneous decrease in the symmetry of the ruthenium complex, with the ruthenium remaining mononuclear and its oxidation state remaining essentially unchanged (as shown by EXAFS and X-ray absorption near-edge structure spectra). The removal of anionic acac ligands from the ruthenium was evidently compensated by the bonding of other anionic ligands, such as hydride from H2 in the feed stream, to form species suggested to be Ru(H)(C{sub 2}H{sub 4}){sub 2}{sup +}, which is coordinatively unsaturated and inferred to react with ethene, leading to the observed formation of butene in a catalytic process.

  14. FTIR spectroscopic characterization of Cu(II) coordination compounds with exopolysaccharide pullulan and its derivatives

    NASA Astrophysics Data System (ADS)

    Miti?, .; Nikoli?, G. S.; Caki?, M.; Premovi?, P.; Ili?, Lj.

    2009-04-01

    Pullulan is a water-soluble, extracellular neutral polysaccharide with a linear flexible chain of ?-(1 ? 6)-linked maltotriose units, the structure of which is intermediate between pullulan and amylose structures because of the co-existence of both ?-(1 ? 6) and ?-(1 ? 4)-glycosidic linkages in single compounds. In alkali solutions Cu(II) ion forms complexes with reduced low-molar pullulan (RLMP). The metal content and the solution composition depends on pH. The complexing process begins in a weak alkali solution (pH > 7), and involves OH groups in C(2) and C(3) or C(6) pullulan monomer units (?- D-glucopyranose). Complexes of Cu(II) ion with reduced low-molar pullulan were synthesized in the water solutions, at the boiling temperature and at different pH values (7.512). Fourier-Transform Infrared (FTIR) spectroscopic data of synthesized complexes are rare in literature. FTIR spectroscopic characterization (FTIR, LNT-FTIR, ATR-FTIR, and FTIR microspectroscopy) of Cu(II) ion complexes with RLMP ( M w 6000 g mol -1) was carried out in this work. The similarities of the ?(C sbnd H) range in a part of FTIR spectra indicate that there is no difference in the conformation of the C 1 glucopyranose (Glc) unit in the RLMP and synthesized Cu(II) complexes. The complexing Cu(II) ion with RLMP in the dependence from the pH form different types of complex (pH 7-8: Cu(II)(Glc) 2(H 2O) 2, pH 8-10: Cu(II)(Glc) 2(H 2O)(OH), pH 10-12: Cu(II)(Glc) 2(OH) 2).

  15. Solution properties and spectroscopic characterization of polymeric precursors to SiNCB and BN ceramic materials

    SciTech Connect

    Cortez, E.; Remsen, E; Chlanda, V.; Carrol, P.; Sneddon, L.

    1998-06-01

    Boron Nitride, BN, and composite SiNCB ceramic fibers are important structural materials because of their excellent thermal and oxidative stabilities. Consequently, polymeric materials as precursors to ceramic composites are receiving increasing attention. Characterization of these materials requires the ability to evaluate simultaneous molecular weight and compositional heterogeneity within the polymer. Size exclusion chromatography equipped with viscometric and refractive index detection as well as coupled to a LC-transform device for infrared absorption analysis has been employed to examine these heterogeneities. Using these combined approaches, the solution properties and the relative amounts of individual functional groups distributed through the molecular weight distribution of SiNCB and BN polymeric precursors were characterized. {copyright} {ital 1998 American Institute of Physics.}

  16. Hafnium(IV) chloride complexes with chelating ?-ketiminate ligands: Synthesis, spectroscopic characterization and volatility study.

    PubMed

    Patil, Siddappa A; Medina, Phillip A; Antic, Aleks; Ziller, Joseph W; Vohs, Jason K; Fahlman, Bradley D

    2015-09-01

    The synthesis and characterization of four new ?-ketiminate hafnium(IV) chloride complexes dichloro-bis[4-(phenylamido)pent-3-en-2-one]-hafnium (4a), dichloro-bis[4-(4-methylphenylamido)pent-3-en-2-one]-hafnium (4b), dichloro-bis[4-(4-methoxyphenylamido)pent-3-en-2-one]-hafnium (4c), and dichloro-bis[4-(4-chlorophenylamido)pent-3-en-2-one]-hafnium (4d) are reported. All the complexes (4a-d) were characterized by spectroscopic methods ((1)H NMR, (13)C NMR, IR), and elemental analysis while the compound 4c was further examined by single-crystal X-ray diffraction, revealing that the complex is monomer with the hafnium center in octahedral coordination environment and oxygens of the chelating N-O ligands are trans to each other and the chloride ligands are in a cis arrangement. Volatile trends are established for four new ?-ketiminate hafnium(IV) chloride complexes (4a-d). Sublimation enthalpies (?Hsub) were calculated from thermogravimetric analysis (TGA) data, which show that, the dependence of ?Hsub on the molecular weight (4a-c) and inductive effects from chlorine (4d). PMID:25897715

  17. Characterization of SiGe/Ge heterostructures and graded layers using variable angle spectroscopic ellipsometry

    NASA Technical Reports Server (NTRS)

    Croke, E. T.; Wang, K. L.; Heyd, A. R.; Alterovitz, S. A.; Lee, C. H.

    1996-01-01

    Variable angle spectroscopic ellipsometry (VASE) has been used to characterize Si(x)Ge(1-x)/Ge superlattices (SLs) grown on Ge substrates and thick Si(x)Ge(1-x)/Ge heterostructures grown on Si substrates. Our VASE analysis yielded the thicknesses and alloy compositions of all layers within the optical penetration depth of the surface. In addition, strain effects were observed in the VASE results for layers under both compressive and tensile strain. Results for the SL structures were found to be in close agreement with high resolution x-ray diffraction measurements made on the same samples. The VASE analysis has been upgraded to characterize linearly graded Si(x)Ge(1-x) buffer layers. The algorithm has been used to determine the total thickness of the buffer layer along with the start and end alloy composition by breaking the total thickness into many (typically more than 20) equal layers. Our ellipsometric results for 1 (mu)m buffer layers graded in the ranges 0.7 less than or = x less than or = 1.0, and 0.5 less than or = x less than or = 1.0 are presented, and compare favorably with the nominal values.

  18. Solvate Structures and Computational/Spectroscopic Characterization of LiPF6 Electrolytes

    SciTech Connect

    Han, Sang D.; Yun, Sung-Hyun; Borodin, Oleg; Seo, D. M.; Sommer, Roger D.; Young, Victor G.; Henderson, Wesley A.

    2015-04-23

    Raman spectroscopy is a powerful method for identifying ion-ion interactions, but only if the vibrational band signature for the anion coordination modes can be accurately deciphered. The present study characterizes the PF6- anion P-F Raman symmetric stretching vibrational band for evaluating the PF6-...Li+ cation interactions within LiPF6 crystalline solvates to create a characterization tool for liquid electrolytes. To facilitate this, the crystal structures for two new solvates(G3)1:LiPF6 and (DEC)2:LiPF6 with triglyme and diethyl carbonate, respectivelyare reported. The information obtained from this analysis provides key guidance about the ionic association information which may be obtained from a Raman spectroscopic evaluation of electrolytes containing the LiPF6 salt and aprotic solvents. Of particular note is the overlap of the Raman bands for both solvent-separated ion pair (SSIP) and contact ion pair (CIP) coordination in which the PF6- anions are uncoordinated or coordinated to a single Li+ cation, respectively.

  19. Toward the characterization of biological toxins using field-based FT-IR spectroscopic instrumentation

    NASA Astrophysics Data System (ADS)

    Schiering, David W.; Walton, Robert B.; Brown, Christopher W.; Norman, Mark L.; Brewer, Joseph; Scott, James

    2004-12-01

    IR spectroscopy is a broadly applicable technique for the identification of covalent materials. Recent advances in instrumentation have made Fourier Transform infrared (FT-IR) spectroscopy available for field characterization of suspect materials. Presently, this instrumentation is broadly deployed and used for the identification of potential chemical hazards. This discussion concerns work towards expanding the analytical utility of field-based FT-IR spectrometry in the characterization of biological threats. Two classes of materials were studied: biologically produced chemical toxins which were non-peptide in nature and peptide toxin. The IR spectroscopic identification of aflatoxin-B1, trichothecene T2 mycotoxin, and strychnine was evaluated using the approach of spectral searching against large libraries of materials. For pure components, the IR method discriminated the above toxins at better than the 99% confidence level. The ability to identify non-peptide toxins in mixtures was also evaluated using a "spectral stripping" search approach. For the mixtures evaluated, this method was able to identify the mixture components from ca. 32K spectral library entries. Castor bean extract containing ricin was used as a representative peptide toxin. Due to similarity in protein spectra, a SIMCA pattern recognition methodology was evaluated for classifying peptide toxins. In addition to castor bean extract the method was validated using bovine serum albumin and myoglobin as simulants. The SIMCA approach was successful in correctly classifying these samples at the 95% confidence level.

  20. Synergic use of TOMS and Aeronet Observations for Characterization of Aerosol Absorption

    NASA Technical Reports Server (NTRS)

    Torres, O.; Bhartia, P. K.; Dubovik, O.; Holben, B.; Siniuk, A.

    2003-01-01

    The role of aerosol absorption on the radiative transfer balance of the earth-atmosphere system is one of the largest sources of uncertainty in the analysis of global climate change. Global measurements of aerosol single scattering albedo are, therefore, necessary to properly assess the radiative forcing effect of aerosols. Remote sensing of aerosol absorption is currently carried out using both ground (Aerosol Robotic Network) and space (Total Ozone Mapping Spectrometer) based observations. The satellite technique uses measurements of backscattered near ultraviolet radiation. Carbonaceous aerosols, resulting from the combustion of biomass, are one of the most predominant absorbing aerosol types in the atmosphere. In this presentation, TOMS and AERONET retrievals of single scattering albedo of carbonaceous aerosols, are compared for different environmental conditions: agriculture related biomass burning in South America and Africa and peat fires in Eastern Europe. The AERONET and TOMS derived aerosol absorption information are in good quantitative agreement. The most absorbing smoke is detected over the African Savanna. Aerosol absorption over the Brazilian rain forest is less absorbing. Absorption by aerosol particles resulting from peat fires in Eastern Europe is weaker than the absorption measured in Africa and South America. This analysis shows that the near UV satellite method of aerosol absorption characterization has the sensitivity to distinguish different levels of aerosol absorption. The analysis of the combined AERONET-TOMS observations shows a high degree of synergy between satellite and ground based observations.

  1. Chemical, spectroscopic characterization, DFT studies and antibacterial activities in vitro of a new gold(I) complex with rimantadine

    NASA Astrophysics Data System (ADS)

    Sucena, Suelen F.; Paiva, Raphael E. F.; Abbehausen, Camilla; Mattos, Ives B.; Lancellotti, Marcelo; Formiga, André L. B.; Corbi, Pedro P.

    2012-04-01

    A novel gold(I) complex with rimantadine (RTD) was obtained and structurally characterized by a set of chemical and spectroscopic analysis. 1H, 13C and 15N nuclear magnetic resonance (NMR) and infrared (IR) spectroscopic measurements suggest coordination of the ligand to Au(I) through the N atom of the ethanamine group. Theoretical (DFT) calculations confirmed the IR assignments and permit proposing an optimized geometry for the complex. The gold(I)-rimantadine complex (Au-RTD) is soluble in methanol, ethanol, dimethylsulfoxide, acetone and acetonitrile. The preliminary kinetic studies based on UV-vis spectroscopic measurements indicate the stability of the compound in solution. Antibacterial activities of the complex were evaluated by an antibiogram assay. The Au-RTD complex showed an effective in vitro antibacterial activity against the Pseudomonas aeruginosa, Escherichia coli (Gram-negative), and Staphylococcus aureus (Gram-positive) bacterial strains.

  2. Raman Spectroscopic Characterization of the Feldspars: Implications for Surface Mineral Characterization in Planetary Exploration

    NASA Technical Reports Server (NTRS)

    Freeman, J. J.; Wang, Alian; Kuebler, K. E.; Haskin, L. A.

    2003-01-01

    The availability in the last decade of improved Raman instrumentation using small, stable, intense lasers, sensitive CCD array detectors, and advanced fast grating systems enabled us to develop the Mars Microbeam Raman Spectrometer (MMRS), a field-portable Raman spectrometer with precision and accuracy capable of identifying minerals and their different compositions. For example, we can determine Mg cation ratios in pyroxenes and olivines to +/-0.1 on the basis of Raman peak positions. Feldspar is another major mineral formed in igneous systems whose characterization is important for determining rock petrogenesis and alteration. From their Raman spectral pattern, feldspars can be readily distinguished from ortho- and chain-silicates and from other tecto-silicates such as quartz and zeolites. We show here how well Raman spectral analysis can distinguish among members within the feldspar group.

  3. Synthesis, Structural and Spectroscopic Characterization, and Reactivities of Mononuclear Cobalt(III)-Peroxo Complexes

    PubMed Central

    Cho, Jaeheung; Sarangi, Ritimukta; Kang, Hye Yeon; Lee, Jung Yoon; Kubo, Minoru; Ogura, Takashi; Solomon, Edward I.; Nam, Wonwoo

    2010-01-01

    Metal-dioxygen adducts are key intermediates detected in the catalytic cycles of dioxygen activation by metalloenzymes and biomimetic compounds. In this study, mononuclear cobalt(III)- peroxo complexes bearing tetraazamacrocyclic ligands, [Co(12-TMC)(O2)]+ and [Co(13-TMC)(O2)]+, were synthesized by reacting [Co(12-TMC)(CH3CN)]2+ and [Co(13-TMC)(CH3CN)]2+, respectively, with H2O2 in the presence of triethylamine. The mononuclear cobalt(III)-peroxo intermediates were isolated and characterized by various spectroscopic techniques and X-ray crystallography, and the structural and spectroscopic characterization demonstrated unambiguously that the peroxo ligand is bound in a side-on ?2 fashion. The O-O bond stretching frequency of [Co(12-TMC)(O2)]+ and [Co(13- TMC)(O2)]+ was determined to be 902 cm?1 by resonance Raman spectroscopy. The structural properties of the CoO2 core in both complexes are nearly identical; the O-O bond distances of [Co(12-TMC)(O2)]+ and [Co(13-TMC)(O2)]+ were 1.4389(17) and 1.438(6) , respectively. The cobalt(III)-peroxo complexes showed reactivities in the oxidation of aldehydes and O2-transfer reactions. In the aldehyde oxidation reactions, the nucleophilic reactivity of the cobalt-peroxo complexes was significantly dependent on the ring size of the macrocyclic ligands, with the reactivity of [Co(13-TMC)(O2)]+ > [Co(12-TMC)(O2)]+. In the O2-transfer reactions, the cobalt(III)-peroxo complexes transferred the bound peroxo group to a manganese(II) complex, affording the corresponding cobalt(II) and manganese(III)- peroxo complexes. The reactivity of the cobalt-peroxo complexes in O2-transfer was also significantly dependent on the ring size of tetraazamacrocycles, and the reactivity order in the O2-transfer reactions was the same as that observed in the aldehyde oxidation reactions. PMID:21062059

  4. Characterization of Photon-Counting Detector Responsivity for Non-Linear Two-Photon Absorption Process

    NASA Technical Reports Server (NTRS)

    Sburlan, S. E.; Farr, W. H.

    2011-01-01

    Sub-band absorption at 1550 nm has been demonstrated and characterized on silicon Geiger mode detectors which normally would be expected to have no response at this wavelength. We compare responsivity measurements to singlephoton absorption for wavelengths slightly above the bandgap wavelength of silicon (approx. 1100 microns). One application for this low efficiency sub-band absorption is in deep space optical communication systems where it is desirable to track a 1030 nm uplink beacon on the same flight terminal detector array that monitors a 1550 nm downlink signal for pointingcontrol. The currently observed absorption at 1550 nm provides 60-70 dB of isolation compared to the response at 1064 nm, which is desirable to avoid saturation of the detector by scattered light from the downlink laser.

  5. Growth and Raman spectroscopic characterization of As 4S 4 (II) single crystals

    NASA Astrophysics Data System (ADS)

    Kyono, Atsushi

    2010-11-01

    As described by Kutoglu (1976 [16]), single crystals of As 4S 4 (II) phase have been grown using a new two-step synthesis that drastically increases the reproducibility that is attainable in synthetic experiments. First, through photo-induced phase transformation, pararealgar powder is prepared as a precursor instead of AsS melt. Then it is dissolved and recrystallized from CS 2 solvent. Results show that single crystals of the As 4S 4 (II) phase were obtained reproducibly through the dissolution-recrystallization process. Single crystals of As 4S 4 (II) obtained using this method were translucent and showed a uniform yellow-orange color. The crystal exhibits a platelet-like shape as a thin film with well-developed faces (0 1 0) and (0 1 0). The grown crystals are as large as 0.500.500.01 mm. They were characterized using powder and single crystal X-ray diffraction techniques to confirm the phase identification and the lattice parameters. The As 4S 4 (II) phase crystallizes in monoclinic system with cell parameters a=11.202(4) , b=9.954(4) , c=7.142(4) , ?=92.81(4), V=795.4(6) 3, which shows good agreement with the former value. Raman spectroscopic studies elucidated the behavior of the substance and the relation among phases of tetra-arsenic tetrasulfide.

  6. Spectroscopic and laser characterization of Yb,Tm:KLu(WO4)2 crystal

    NASA Astrophysics Data System (ADS)

    Loiko, P. A.; Serres, J. M.; Mateos, X.; Demesh, M. P.; Yasukevich, A. S.; Yumashev, K. V.; Petrov, V.; Griebner, U.; Aguil, M.; Daz, F.

    2016-01-01

    We report on a comprehensive spectroscopic and laser characterization of monoclinic Yb,Tm:KLu(WO4)2 crystals. Stimulated-emission cross-section spectra corresponding to the 3F4 ? 3H6 transition of Tm3+ ions are determined. The radiative lifetime of the 3F4 state of Tm3+ ions is 0.82 ms. The maximum Yb3+ ? Tm3+ energy transfer efficiency is 83.9% for 5 at.% Yb - 8 at.% Tm doping. The fractional heat loading for Yb,Tm:KLu(WO4)2 is 0.45 0.05. Using a hemispherical cavity and 5 at.% Yb - 6 at.% Tm doped crystal, a maximum CW power of 227 mW is achieved at 1.983-2.011 ?m with a maximum slope efficiency ? = 14%. In the microchip laser set-up, the highest slope efficiency is 20% for a 5 at.% Yb- 8 at.% Tm doped crystal with a maximum output power of 201 mW at 1.99-2.007 ?m. Operation of Yb,Tm:KLu(WO4)2 as a vibronic laser emitting at 2.081-2.093 ?m is also demonstrated.

  7. Spectroscopic and Electrochemical Characterization of Nanostructured Optically-Transparent Carbon Electrodes

    PubMed Central

    Benavidez, Tomas E.; Garcia, Carlos D.

    2013-01-01

    The present paper describes the results related to the optical and electrochemical characterization of thin carbon films fabricated by spin coating and pyrolysis of AZ P4330-RS photoresist. The goal of this paper is to provide comprehensive information allowing for the rational the selection of the conditions to fabricate optically-transparent carbon electrodes (OTCE) with specific electro-optical properties. According to our results, these electrodes could be appropriate choices as electrochemical transducers to monitor electrophoretic separations. At the core of this manuscript is the development and critical evaluation of a new optical model to calculate the thickness of the OTCE by variable angle spectroscopic ellipsometry (VASE). Such data was complemented with topography and roughness (obtained by AFM), electrochemical properties (obtained by cyclic voltammetry), electrical properties (obtained by electrochemical impedance spectroscopy), and structural composition (obtained by Raman spectroscopy). Although the described OTCE were used as substrates to investigate the effect of electrode potential on the real-time adsorption of proteins by ellipsometry, these results could enable the development of other biosensors that can be then integrated into various CE platforms. PMID:23595607

  8. Spectroscopic characterization of Cr2+ ions in ZnSe/ZnS crystals under visible excitation

    NASA Astrophysics Data System (ADS)

    Peppers, Jeremy M.; Fedorov, Vladimir V.; Mirov, Sergey B.

    2015-02-01

    Detailed spectroscopic characterization of Cr:ZnSe (Cr:ZnS) crystals under visible excitation into the charge transfer bands of Cr2+ impurities was performed. Middle infrared photoluminescence of Cr:ZnS under this excitation exhibits shorter rise time (~150ns) than that previously observed in Cr:ZnSe (~4-10 ?s). As a result the quantum yield of Cr:ZnS mid-IR photoluminescence under 10ns pulsed 416nm excitation into the charge transfer band was estimated at close to 100%, which contrasts with low (~14%) quantum yield measured in Cr:ZnSe under 532nm pulsed excitation, indicating the possibility of efficient excitation of the upper laser level of Cr:ZnS using this mechanism. The rise time can be caused by cascade relaxation from higher lying levels through the 3T1 metastable level, producing luminescence in the near-IR. Measurements of the temperature dependence of the middle- and near infrared photoluminescence signals are reported. These values indicated that more efficient pumping of Cr:ZnSe under 532nm excitation can be achieved at temperatures greater than 300 K. Results of high temperature laser experiments supporting this idea are presented.

  9. Spectroscopic ellipsometric characterization of Si/Si(1-x)Ge(x) strained-layer superlattices

    NASA Technical Reports Server (NTRS)

    Yao, H.; Woollam, J. A.; Wang, P. J.; Tejwani, M. J.; Alterovitz, S. A.

    1993-01-01

    Spectroscopic ellipsometry (SE) was employed to characterize Si/Si(1-x)Ge(x) strained-layer superlattices. An algorithm was developed, using the available optical constants measured at a number of fixed x values of Ge composition, to compute the dielectric function spectrum of Si(1-x)Ge(x) at an arbitrary x value in the spectral range 17 to 5.6 eV. The ellipsometrically determined superlattice thicknesses and alloy compositional fractions were in excellent agreement with results from high-resolution x ray diffraction studies. The silicon surfaces of the superlattices were subjected to a 9:1 HF cleaning prior to the SE measurements. The HF solution removed silicon oxides on the semiconductor surface, and terminated the Si surface with hydrogen-silicon bonds, which were monitored over a period of several weeks, after the HF cleaning, by SE measurements. An equivalent dielectric layer model was established to describe the hydrogen-terminated Si surface layer. The passivated Si surface remained unchanged for greater than 2 h, and very little surface oxidation took place even over 3 to 4 days.

  10. Characterization of organic matter from composting of different residues by physicochemical and spectroscopic methods.

    PubMed

    Fialho, Lucimar Lopes; Lopes da Silva, Wilson Tadeu; Milori, Débora M B P; Simões, Marcelo Luiz; Martin-Neto, Ladislau

    2010-03-01

    Chemical and spectroscopic methods were used to characterize organic matter transformations during the composting process. Four different residue mixtures were studied: P1--garden trimmings (GT) only, P2 - GT plus fresh cattle manure, P3--GT plus orange pomace and P4--GT plus filter cake. The thermophilic phase was not reached in P1 compost, but the P2, P3 and P4 composts showed all three typical process phases. The thermophilic phase and CEC/C ratio stabilized after 90 days, while C/N ratio and the ash content stabilized after 60 days. The increasing E(4)/E(6) ratio indicated oxidation reactions occurring during the process in the material from P2, P3 and P4. The (13)C NMR and FTIR results suggested extraction of both pectin and lignin in the HA-like fraction. The CEC/C ratio, temperature and E(4)/E(6) ratio showed that within 90 days P2, P3 and P4 composts were humified. However, material from P1 did not show characteristics of humified compost. From these data, it is apparent that C/N ratio and ash content are not reliable methods for monitoring the composting process. PMID:19954966

  11. Smooth and conductive DNA-templated Cu₂O nanowires: growth morphology, spectroscopic and electrical characterization.

    PubMed

    Hassanien, Reda; Al-Said, Said A Farha; Siller, Lidija; Little, Ross; Wright, Nicholas G; Houlton, Andrew; Horrocks, Benjamin R

    2012-02-24

    DNA strands have been used as templates for the self-assembly of smooth and conductive cuprous oxide (Cu₂O) nanowires of diameter 12-23 nm and whose length is determined by the template (16 μm for λ-DNA). A combination of spectroscopic, diffraction and probe microscopy techniques showed that these nanowires comprise single crystallites of Cu₂O bound to the DNA molecules which fused together over time in a process analogous to Ostwald ripening, but driven by the free energy of interaction with the template as well as the surface tension. Electrical characterization of the nanowires by a non-contact method, scanned conductance microscopy and by contact mode conductive AFM showed the wires are electrically conductive. The conductivity estimated from the AFM cross section and the zero-bias conductance in conductive AFM experiments was 2.2-3.3 S cm⁻¹. These Cu₂O nanowires are amongst the thinnest reported and show evidence of strong quantum confinement in electronic spectra. PMID:22261265

  12. An X-ray absorption spectroscopic structural investigation of the nickel site in Escherichia coli NikA protein

    SciTech Connect

    Allan, C.B.; Gu, Z.; Choudhury, S.B.; Al-Mjeni, F.; Sharma, M.L.; Maroney, M.J.; Wu, L.F.; Mandrand-Berthelot, M.A.

    1998-11-02

    Since the discovery of the involvement of Ni in the active site of the enzyme urease in 1975, the role of Ni in biology has been rapidly expanding. The list of nickel-dependent metalloenzymes now includes acetyl coenzyme A synthase/carbon monoxide dehydrogenase, methyl coenzyme M reductase, Ni/Fe hydrogenases, and superoxide dismutases from Streptomyces. Each of these enzymes appears to be dependent on several gene products that constitute a Ni-specific transport and metallocenter assembly system. The authors report here the results of an X-ray spectroscopic structural investigation of the Ni site in a Ni transport protein, the periplasmic Ni-binding protein, NikA, from Escherichia coli.

  13. Development of Cellular Absorptive Tracers (CATs) for a Quantitative Characterization of Microbial Mass in Flow Systems

    SciTech Connect

    Saripalli, Prasad; Brown, Christopher F.; Lindberg, Michael J.

    2005-03-16

    We report on a new Cellular Absorptive Tracers (CATs) method, for a simple, non-destructive characterization of bacterial mass in flow systems. Results show that adsorption of a CAT molecule into the cellular mass results in its retardation during flow, which is a good, quantitative measure of the biomass quantity and distribution. No such methods are currently available for a quantitative characterization of cell mass.

  14. Spectroscopic method for Earth-satellite-Earth laser long-path absorption measurements using Retroreflector In Space (RIS)

    NASA Technical Reports Server (NTRS)

    Sugimoto, Nobuo; Minato, Atsushi; Sasano, Yasuhiro

    1992-01-01

    The Retroreflector in Space (RIS) is a single element cube-corner retroreflector with a diameter of 0.5 m designed for earth-satellite-earth laser long-path absorption experiments. The RIS is to be loaded on the Advanced Earth Observing System (ADEOS) satellite which is scheduled for launch in Feb. 1996. The orbit for ADEOS is a sun synchronous subrecurrent polar-orbit with an inclination of 98.6 deg. It has a period of 101 minutes and an altitude of approximately 800 km. The local time at descending node is 10:15-10:45, and the recurrent period is 41 days. The velocity relative to the ground is approximately 7 km/s. In the RIS experiment, a laser beam transmitted from a ground station is reflected by RIS and received at the ground station. The absorption of the intervening atmosphere is measured in the round-trip optical path.

  15. A Multiscale Vibrational Spectroscopic Approach for Identification and Biochemical Characterization of Pollen

    PubMed Central

    Bağcıoğlu, Murat; Zimmermann, Boris; Kohler, Achim

    2015-01-01

    Background Analysis of pollen grains reveals valuable information on biology, ecology, forensics, climate change, insect migration, food sources and aeroallergens. Vibrational (infrared and Raman) spectroscopies offer chemical characterization of pollen via identifiable spectral features without any sample pretreatment. We have compared the level of chemical information that can be obtained by different multiscale vibrational spectroscopic techniques. Methodology Pollen from 15 different species of Pinales (conifers) were measured by seven infrared and Raman methodologies. In order to obtain infrared spectra, both reflectance and transmission measurements were performed on ground and intact pollen grains (bulk measurements), in addition, infrared spectra were obtained by microspectroscopy of multigrain and single pollen grain measurements. For Raman microspectroscopy measurements, spectra were obtained from the same pollen grains by focusing two different substructures of pollen grain. The spectral data from the seven methodologies were integrated into one data model by the Consensus Principal Component Analysis, in order to obtain the relations between the molecular signatures traced by different techniques. Results The vibrational spectroscopy enabled biochemical characterization of pollen and detection of phylogenetic variation. The spectral differences were clearly connected to specific chemical constituents, such as lipids, carbohydrates, carotenoids and sporopollenins. The extensive differences between pollen of Cedrus and the rest of Pinaceae family were unambiguously connected with molecular composition of sporopollenins in pollen grain wall, while pollen of Picea has apparently higher concentration of carotenoids than the rest of the family. It is shown that vibrational methodologies have great potential for systematic collection of data on ecosystems and that the obtained phylogenetic variation can be well explained by the biochemical composition of pollen. Out of the seven tested methodologies, the best taxonomical differentiation of pollen was obtained by infrared measurements on bulk samples, as well as by Raman microspectroscopy measurements of the corpus region of the pollen grain. Raman microspectroscopy measurements indicate that measurement area, as well as the depth of focus, can have crucial influence on the obtained data. PMID:26376486

  16. X-ray absorption spectroscopic studies of the active sites of nickel- and copper-containing metalloproteins

    SciTech Connect

    Tan, G.O.

    1993-06-01

    X-ray absorption spectroscopy (XAS) is a useful tool for obtaining structural and chemical information about the active sites of metalloproteins and metalloenzymes. Information may be obtained from both the edge region and the extended X-ray absorption fine structure (EXAFS) or post-edge region of the K-edge X-ray absorption spectrum of a metal center in a compound. The edge contains information about the valence electronic structure of the atom that absorbs the X-rays. It is possible in some systems to infer the redox state of the metal atom in question, as well as the geometry and nature of ligands connected to it, from the features in the edge in a straightforward manner. The EXAFS modulations, being produced by the backscattering of the ejected photoelectron from the atoms surrounding the metal atom, provide, when analyzed, information about the number and type of neighbouring atoms, and the distances at which they occur. In this thesis, analysis of both the edge and EXAFS regions has been used to gain information about the active sites of various metalloproteins. The metalloproteins studied were plastocyanin (Pc), laccase and nickel carbon monoxide dehydrogenase (Ni CODH). Studies of Cu(I)-imidazole compounds, related to the protein hemocyanin, are also reported here.

  17. Structural and spectroscopic characterization of a thiosemicarbazidatodioxouranium(VI) complex: A combined experimental and DFT study

    NASA Astrophysics Data System (ADS)

    ?ahin, Musa; zdemir, Nam?k; Bal-Demirci, Tlay; lkseven, Bahri; Diner, Muharrem; Soylu, Mustafa Serkan

    2015-01-01

    The title thiosemicarbazidatodioxouranium(VI) compound was synthesized and characterized by FT-IR, NMR and UV-vis spectroscopies. Solid-state structure of the compound was confirmed by X-ray crystallography. Besides, the molecular geometry, vibrational frequencies and gauge-independent atomic orbital (GIAO) 1H and 13C NMR chemical shift values of the compound in the ground state have been calculated using the density functional theory (DFT/B3LYP) method with the 6-311++G(d,p) basis set for the C, H, Cl, N, O, S atoms and SDD pseudo-potential for the U atom, and compared with the experimental data. Using the TD-DFT method, electronic absorption spectra of the compound have been predicted at same level. As a result, a good agreement is obtained between the experimental and theoretical ones.

  18. Speciation of water soluble iron in size segregated airborne particulate matter using LED based liquid waveguide with a novel dispersive absorption spectroscopic measurement technique.

    PubMed

    Chan, K L; Jiang, S Y N; Ning, Z

    2016-03-31

    In this study, we present the development and evaluation of a dispersive absorption spectroscopic technique for trace level soluble ferrous detection. The technique makes use of the broadband absorption spectra of the ferrous-ferrozine complex with a novel spectral fitting algorithm to determine soluble ferrous concentrations in samples and achieves much improved measurement precision compared to conventional methods. The developed method was evaluated by both model simulations and experimental investigations. The results demonstrated the robustness of the method against the spectral fluctuation, wavelength drift and electronic noise, while achieving excellent linearity (R(2) > 0.999) and low detection limit (0.06 μg L(-1)) for soluble ferrous detection. The developed method was also used for the speciation of soluble iron in size segregated atmospheric aerosols. The measurement was carried out during Spring and Summer in typical urban environment in Hong Kong. The measured total iron concentrations are in good agreement compared to conventional Inductively Coupled Plasma - Optical Emission Spectroscopy (ICP-OES) measurements. Investigation on ambient particulate matter samples shows the size dependent characteristic of iron speciation in the atmosphere with a more active role of fine particles in transforming between ferrous and ferric. The method demonstrated in this study provides a cost and time effective approach for the speciation of iron in ambient aerosols. PMID:26965332

  19. Norharmane rhenium(I) polypyridyl complexes: synthesis, structural and spectroscopic characterization.

    PubMed

    Maisuls, Iván; Wolcan, Ezequiel; Piro, Oscar E; Etcheverría, Gustavo A; Petroselli, Gabriela; Erra-Ballsels, Rosa; Cabrerizo, Franco M; Ruiz, Gustavo T

    2015-10-21

    Two novel Re(i) complexes with the general formula fac-[Re(CO)3(L)(nHo)]CF3SO3, where L = 2,2'-bipyridine (bpy) or 1,10 phenanthroline (phen) and nHo (9H-pyrido[3,4-b]indole; norharmane) have been synthesized. The Re(i)-nHo complexes were characterized by structural X-ray diffraction, (1)H and (13)C NMR, UV-vis absorption and FT-IR spectroscopy, and by a combination of two mass spectrometry techniques, namely ESI-MS and UV-MALDI-MS. All characterizations showed that nHo is coordinated to the metal atom by the pyridine nitrogen of the molecule. X-ray structural analysis revealed that the crystal lattices for both complexes are further stabilized by a strong >N-HO bond between the pyrrole NH group of the pyridoindole ligand and one oxygen atom of the trifluoromethanesulfonate counter-ion. Ground state geometry optimization by DFT calculations showed that in fluid solution the nHo ligand may rotate freely. The nature of the electronic transitions of Re(CO)3(bpy)(nHo)(+) were established by TD-DFT calculations. The set of the most important electronic transitions present in this complex are comprised of π→π* electronic transitions centered on bpy and nHo moieties, LLCTnHo→COs, MLLCTRe(CO)3→bpy and LLCTnHo→bpy transitions. Additionally, TD-DFT calculations predict the existence of another two intense MLLCTRe(CO)3→nHo electronic transitions. Calculated UV-vis absorption spectra are in good agreement with the corresponding experimental data for the bpy-containing complex. PMID:26365709

  20. Spectroscopic characterization and energy transfer process in cobalt and cobalt-iron co-doped ZnSe/ZnS crystals

    NASA Astrophysics Data System (ADS)

    Peppers, J.; Martyshkin, D. V.; Fedorov, V. V.; Mirov, S. B.

    2014-02-01

    Cobalt doped II-VI wide band semiconductors (e.g. ZnSe, ZnS, CdSe) are promising media for infrared (IR) laser applications. They could be utilized as effective passive Q-switches for cavities of Alexandrite as well as Nd and Er lasers operating over 0.7-0.8, 1.3-1.6, and ~2.8 μm spectral ranges. We report spectroscopic characterization of Co:ZnSe and Co:ZnS crystals. Absorption cross-sections were measured for 4A2(F) → 4T1(P), 4A2(F) → 4T1(F), and 4A2(F) → 4T2(F) transitions with maximum absorption at 768(726), 1615(1500), 2690(2740) nm for ZnSe(ZnS) crystals, respectively. The calculated absorption cross-sections of the above transitions were estimated to be 64(56)×1019, 7.5(7.8)×1019, and 0.52(0.49)×1019 cm2 for ZnSe(ZnS) crystal hosts. In addition to the above applications the cobalt ions could be utilized for excitation of Fe2+ ions via resonance energy transfer process. Tunable room temperature lasing of Fe 2+ doped binary and ternary chalcogenides has been successfully demonstrated over 3.5-6 μm spectral range. However, II-VI lasers based on Fe2+ active ions don't feature convenient commercially available pump sources (e.g. some Fe doped crystal hosts require pump wavelengths longer than 3 μm). Therefore, the process of energy transfer from Co2+ to Fe2+ ions could enable utilization of commercially available visible and near-infrared pump sources. We report a spectroscopic characterization of iron-cobalt co-doped ZnS and ZnSe crystals over 14-300K temperature range. Mid-IR laser oscillation at 3.9 μm(3.6 μm) via energy transfer in the Co:Fe:ZnSe (Co:Fe:ZnS) co-doped crystals was demonstrated under cobalt excitation at 4A2(F) → 4T1(P) (~0.7μm) and 4A2(F) → 4T1(F) (~1.56 μm) transitions.

  1. Spectroscopic characterization and density functional studies of (Z)-1-[(2-methoxy-5-(trifluoromethyl)phenylamino)methylene]naphthalene-2(1H)-one

    NASA Astrophysics Data System (ADS)

    Alpaslan, Yelda Bingöl; Gökce, Halil; Alpaslan, Gökhan; Macit, Mustafa

    2015-10-01

    In the current work, the Schiff base compound (Z)-1-[(2-Methoxy-5-(trifluoromethyl)phenylamino)methylene]naphthalene-2(1H)-one (I) has been characterized by using 13C NMR, 1H NMR, FT-IR and UV-vis spectroscopic techniques. Molecular geometry of the compound I in the ground state, vibrational frequencies, electronic absorption spectra and gauge including atomic orbital (GIAO) 1H and 13C NMR chemical shift values have been calculated by using the density functional method (DFT) with 6-311++G(d,p) basis set and compared with the experimental data. The optimized geometric parameters obtained by using DFT (B3LYP/6-311++G(d,p)) show good agreement with the experimental data. The vibrational frequencies were determined based on the recorded FT-IR spectra in the range of 4000-400 cm-1 for solid state. Using the TD-DFT method, electronic absorption spectra of the compound I have been predicted and good agreement is determined with the experimental ones. In addition, molecular electrostatic potential (MEP), frontier molecular orbital analysis (HOMO-LUMO), non-linear optical (NLO) properties, NBO analysis and NBO atomic charges of the compound I were investigated using same theoretical calculations.

  2. Spectroscopic characterization of the postsedimentary alterations of Ostrava-Karvina coals

    SciTech Connect

    Machovic, M; Sebestova, E.; Pavlikova, H.; Taraba, B.

    1994-12-31

    Spectroscopic methods provide useful information about the compositional changes of coal caused by in situ alteration in the coal seam. In Czechoslovakia, altered coals result from postsedimentary oxidation or thermal degradation of coal organic matter. Spectroscopic methods (FTIR, EPR, {sup 13}C CP/MAS NMR) have been used to determine the degree of alteration of coals from the Ostrava-Karvina basin. Useful parameters were found that included the contents of the aliphatic and aromatic C-H bonds, carbonyl groups, and the aromaticity of coals and EPR line width. Spectroscopic parameters were correlated with the spontaneous combustion characteristics of coals.

  3. Characterization of ion-assisted induced absorption in A-Si thin-films used for multivariate optical computing

    NASA Astrophysics Data System (ADS)

    Nayak, Aditya B.; Price, James M.; Dai, Bin; Perkins, David; Chen, Ding Ding; Jones, Christopher M.

    2015-06-01

    Multivariate optical computing (MOC), an optical sensing technique for analog calculation, allows direct and robust measurement of chemical and physical properties of complex fluid samples in high-pressure/high-temperature (HP/HT) downhole environments. The core of this MOC technology is the integrated computational element (ICE), an optical element with a wavelength-dependent transmission spectrum designed to allow the detector to respond sensitively and specifically to the analytes of interest. A key differentiator of this technology is it uses all of the information present in the broadband optical spectrum to determine the proportion of the analyte present in a complex fluid mixture. The detection methodology is photometric in nature; therefore, this technology does not require a spectrometer to measure and record a spectrum or a computer to perform calculations on the recorded optical spectrum. The integrated computational element is a thin-film optical element with a specific optical response function designed for each analyte. The optical response function is achieved by fabricating alternating layers of high-index (a-Si) and low-index (SiO2) thin films onto a transparent substrate (BK7 glass) using traditional thin-film manufacturing processes (e.g., ion-assisted e-beam vacuum deposition). A proprietary software and process are used to control the thickness and material properties, including the optical constants of the materials during deposition to achieve the desired optical response function. The ion-assisted deposition is useful for controlling the densification of the film, stoichiometry, and material optical constants as well as to achieve high deposition growth rates and moisture-stable films. However, the ion-source can induce undesirable absorption in the film; and subsequently, modify the optical constants of the material during the ramp-up and stabilization period of the e-gun and ion-source, respectively. This paper characterizes the unwanted absorption in the a-Si thin-film using advanced thin-film metrology methods, including spectroscopic ellipsometry and Fourier transform infrared (FTIR) spectroscopy. The resulting analysis identifies a fundamental mechanism contributing to this absorption and a method for minimizing and accounting for the unwanted absorption in the thin-film such that the exact optical response function can be achieved.

  4. Absorption spectroscopy characterization measurements of a laser-produced Na atomic beam

    SciTech Connect

    Ching, C.H.; Bailey, J.E.; Lake, P.W.; Filuk, A.B.; Adams, R.G.; McKenney, J.

    1996-06-01

    This work describes a pulsed Na atomic beam source developed for spectroscopic diagnosis of a high-power ion diode on the Particle Beam Fusion Accelerator II. The goal is to produce a {approximately} 10{sup 12}-cm{sup {minus}3}-density Na atomic beam that can be injected into the diode acceleration gap to measure electric and magnetic fields from the Stark and Zeeman effects through laser-induced-fluorescence or absorption spectroscopy. A {approximately} 10 ns fwhm, 1.06 {micro}m, 0.6 J/cm{sup 2} laser incident through a glass slide heats a Na-bearing thin film, creating a plasma that generates a sodium vapor plume. A {approximately} 1 {micro}sec fwhm dye laser beam tuned to 5,890 {angstrom} is used for absorption measurement of the Na I resonant doublet by viewing parallel to the film surface. The dye laser light is coupled through a fiber to a spectrograph with a time-integrated CCD camera. A two-dimensional mapping of the Na vapor density is obtained through absorption measurements at different spatial locations. Time-of-flight and Doppler broadening of the absorption with {approximately} 0.1 {angstrom} spectral resolution indicate that the Na neutral vapor temperature is about 0.5 to 2 eV. Laser-induced-fluorescence from {approximately} 1 {times} 10{sup 12}-cm{sup {minus}3} Na I 3s-3p lines observed with a streaked spectrograph provides a signal level sufficient for {approximately} 0.06 {angstrom} wavelength shift measurements in a mock-up of an ion diode experiment.

  5. X-ray absorption fine structure spectroscopic determination of plutonium speciation at the Rocky Flats environmental technology

    SciTech Connect

    Lezama-pacheco, Juan S; Conradson, Steven D; Clark, David L

    2008-01-01

    X-ray Absorption Fine Structure spectroscopy was used to probe the speciation of the ppm level Pu in thirteen soil and concrete samples from the Rocky Flats Environmental Technology Site in support of the site remediation effort that has been successfully completed since these measurements. In addition to X-ray Absorption Near Edge Spectra, two of the samples yielded Extended X-ray Absorption Fine Structure spectra that could be analyzed by curve-fits. Most of these spectra exhibited features consistent with PU(IV), and more specificaJly, PuO{sub 2+x}-type speciation. Two were ambiguous, possibly indicating that Pu that was originally present in a different form was transforming into PuO{sub 2+x}, and one was interpreted as demonstrating the presence of an unusual Pu(VI) compound, consistent with its source being spills from a PUREX purification line onto a concrete floor and the resultant extreme conditions. These experimental results therefore validated models that predicted that insoluble PuO{sub 2+x} would be the most stable form of Pu in equilibrium with air and water even when the source terms were most likely Pu metal with organic compounds or a Pu fire. A corollary of these models' predictions and other in situ observations is therefore that the minimal transport of Pu that occurred on the site was via the resuspension and mobilization of colloidal particles. Under these conditions, the small amounts of diffusely distributed Pu that were left on the site after its remediation pose only a negligible hazard.

  6. Porphyrins with exocyclic rings. 16. Synthesis and spectroscopic characterization of fluoranthoporphyrins, a new class of highly conjugated porphyrin chromophores.

    PubMed

    Lash, T D; Werner, T M; Thompson, M L; Manley, J M

    2001-05-01

    Porphyrins with fused aromatic rings are under detailed investigation due to their unique spectroscopic properties. To gain more insights into the effects due to ring annealation on the porphyrin chromophore, a series of fluoranthoporphyrins have been synthesized. Reaction of 3-nitrofluoranthene with isocyanoacetate esters in the presence of a phosphazene base afforded good yields of the fluorantho[2,3-c]pyrrole esters 8. Cleavage of the ester moiety with KOH in ethylene glycol afforded the parent heterocycle 9, and this condensed with 2 equiv of acetoxymethylpyrroles 10 in refluxing acetic acid-2-propanol to afford tripyrranes 11. Following cleavage of the tert-butyl ester protective groups with TFA, "3 + 1" condensation with pyrrole dialdehyde 12 gave the fluoranthoporphyrins 13 in good overall yields. In addition, reaction of tripyrrane 11 with acenaphthopyrrole dialdehyde 16 gave the mixed acenaphthofluoranthoporphyrin 17 in excellent yields. A difluoranthoporphyrin 18 was also prepared via a "2 + 2" MacDonald condensation. Reaction of fluoranthopyrrole 8a with dimethoxymethane in the presence of p-toluenesulfonic acid gave the symmetrical dipyrrylmethane 19, and following ester saponification, this was condensed with a dipyrrylmethane dialdehyde to afford the adj-difluoranthoporphyrin 18. The UV--vis spectra for these fluoranthoporphyrins gave a series of three broadened absorptions in the Soret band region, although the Q-bands were little effected by ring fusion. The nickel(II), copper(II), and zinc chelates were more unusual, showing strong absorptions near 600 nm. Difluoranthoporphyrin 18 showed many of the same spectroscopic features, although the presence of two ring fusions gave rise to an increase in the spectroscopic shifts. The mixed system 17 gave spectra that showed larger red shifts due to the acenaphthylene unit combined with the features due to the fluoranthene rings. This work further demonstrates the utility of aromatic ring fusion in altering the properties of porphyrinoid systems. PMID:11325282

  7. Quantification of point-source emissions of CO2 and CH4 using airborne absorption spectroscopic remote sensing

    NASA Astrophysics Data System (ADS)

    Bovensmann, H.; Gerilowski, K.; Krings, T.; Buchwitz, M.; Sachs, T.; Erzinger, J.; Burrows, J. P.

    2012-04-01

    Many natural and anthropogenic emissions of CO2 and CH4 occure on small to point scales. Examples are the CO2 release by volcanoes, power plants, steel and cement production, as well as CH4 release by mud volcanoes, large seeps, land fills or open coal mines and coal mine venting. Quantifying and verifying these emissions by independent, non-intrusive (here remote sensing) techniques is required in the context of a better understanding and management these sources. The data of airborne absorption spectrometer covering the relevant spectral absorptions of CO2 and CH4 has the potential to contribute to this research and application area. Recent achievements using the Methane Airborne MAPper (MAMAP) sensor - developed by the University of Bremen in cooperation with the GFZ Potsdam - show that CO2 as well as CH4 point source emissions can be derived from column averaged dry air mole fractions of CO2 and CH4 retrieved from airborne passive nadir remote sensing measurements. The developed techniques are also relevant in the context of future CO2 and CH4 satellite missions like OCO-2 and CarbonSat. The paper will present first results of two campaigns performed in 2011 covering anthropogenic as well as geologic point sources of CO2 and CH4. The potential and limitations for future applications will be discussed.

  8. Absorption and fluorescence spectroscopic characterisation of the circadian blue-light photoreceptor cryptochrome from Drosophila melanogaster (dCry)

    NASA Astrophysics Data System (ADS)

    Shirdel, J.; Zirak, P.; Penzkofer, A.; Breitkreuz, H.; Wolf, E.

    2008-09-01

    The absorption and fluorescence behaviour of the circadian blue-light photoreceptor cryptochrome from Drosophila melanogaster (dCry) in a pH 8 aqueous buffer solution is studied. The flavin adenine dinucleotide (FAD) cofactor of dCry is identified to be present in its oxidized form (FAD ox), and the 5,10-methenyltetrahydrofolate (MTHF) cofactor is found to be hydrolyzed and oxidized to 10-formyldihydrofolate (10-FDHF). The absorption and the fluorescence behaviour of dCry is investigated in the dark-adapted (receptor) state, the light-adapted (signalling) state, and under long-time violet light exposure. Photo-excitation of FAD ox in dCry causes a reductive electron transfer to the formation of anionic FAD semiquinone (FAD rad - ), and photo-excitation of the generated FAD rad - causes an oxidative electron transfer to the back formation of FAD ox. In light adapted dCry a photo-induced equilibrium between FAD ox and FAD rad - exists. The photo-cycle dynamics of signalling state formation and recovery is discussed. Quantum yields of photo-induced signalling state formation of about 0.2 and of photo-induced back-conversion of about 0.2 are determined. A recovery of FAD rad - to FAD ox in the dark with a time constant of 1.6 min at room temperature is found.

  9. PROBING THE FERMI BUBBLES IN ULTRAVIOLET ABSORPTION: A SPECTROSCOPIC SIGNATURE OF THE MILKY WAY'S BICONICAL NUCLEAR OUTFLOW

    SciTech Connect

    Fox, Andrew J.; Bordoloi, Rongmon; Hernandez, Svea; Tumlinson, Jason; Savage, Blair D.; Wakker, Bart P.; Lockman, Felix J.; Bland-Hawthorn, Joss; Kim, Tae-Sun; Benjamin, Robert A.

    2015-01-20

    Giant lobes of plasma extend ≈55° above and below the Galactic center, glowing in emission from gamma rays (the Fermi Bubbles) to microwaves and polarized radio waves. We use ultraviolet absorption-line spectra from the Hubble Space Telescope to constrain the velocity of the outflowing gas within these regions, targeting the quasar PDS 456 (ℓ, b = 10.°4, +11.°2). This sightline passes through a clear biconical structure seen in hard X-ray and gamma-ray emission near the base of the northern Fermi Bubble. We report two high-velocity metal absorption components, at v {sub LSR} = –235 and +250 km s{sup –1}, which cannot be explained by co-rotating gas in the Galactic disk or halo. Their velocities are suggestive of an origin on the front and back side of an expanding biconical outflow emanating from the Galactic center. We develop simple kinematic biconical outflow models that can explain the observed profiles with an outflow velocity of ≳900 km s{sup –1} and a full opening angle of ≈110° (matching the X-ray bicone). This indicates Galactic center activity over the last ≈2.5-4.0 Myr, in line with age estimates of the Fermi Bubbles. The observations illustrate the use of UV spectroscopy to probe the properties of swept-up gas venting into the Fermi Bubbles.

  10. Melanin from the nitrogen-fixing bacterium Azotobacter chroococcum: a spectroscopic characterization.

    PubMed

    Banerjee, Aulie; Supakar, Subhrangshu; Banerjee, Raja

    2014-01-01

    Melanins, the ubiquitous hetero-polymer pigments found widely dispersed among various life forms, are usually dark brown/black in colour. Although melanins have variety of biological functions, including protection against ultraviolet radiation of sunlight and are used in medicine, cosmetics, extraction of melanin from the animal and plant kingdoms is not an easy task. Using complementary physicochemical techniques (i.e. MALDI-TOF, FTIR absorption and cross-polarization magic angle spinning solid-state (13)C NMR), we report here the characterization of melanins extracted from the nitrogen-fixing non-virulent bacterium Azotobacter chroococcum, a safe viable source. Moreover, considering dihydroxyindole moiety as the main constituent, an effort is made to propose the putative molecular structure of the melanin hetero-polymer extracted from the bacterium. Characterization of the melanin obtained from Azotobacter chroococcum would provide an inspiration in extending research activities on these hetero-polymers and their use as protective agent against UV radiation. PMID:24416247

  11. Spectroscopic characterization of the binding mechanism of fluorescein and carboxyfluorescein in human serum albumin

    NASA Astrophysics Data System (ADS)

    Sulaiman, Saba A. J.; Kulathunga, H. Udani; Abou-Zied, Osama K.

    2015-03-01

    Fluorescein (FL) and some of its precursors have proven to be effective fluorescent tracers in pharmaceutical and medical applications owing to their high quantum yield of fluorescence in physiological conditions and their high membrane permeability. In order to protect FL from metabolic effects during the process of its delivery, human serum albumin (HSA) has been used as a carrier because of its compatibility with the human body. In the present work, we used spectroscopic methods to characterize the binding mechanisms of FL and one of its derivatives, 5(6)- carboxyfluorescein (CFL), in the HSA protein. The absorbance change of the two ligands (FL and CFL) was quantified as a function of the HSA concentration and the results indicate a moderate binding strength for the two ligands inside HSA (1.00 +/- 0.12 x 104 M-1). The quenching effect of FL(CFL) on the fluorescence intensity of W214 (the sole tryptophan in HSA) indicates that FL and CFL occupy Site I in the protein which is known to bind several hydrophobic drugs. By performing site-competitive experiments, the location of the ligands is determined to be similar to that of the anticoagulant drug warfarin. At higher ratios of [ligand]/[HSA], we observed an upward curvature in the Stern-Volmer plots which indicates that the ligands occupy more pockets in Site I, close to W214. Our results indicate that both ligands bind in HSA with a moderate strength that should not affect their release when used as fluorescent reporters. The chemical and physical identities of the two ligands are also preserved inside the HSA binding sites.

  12. Spectroscopic Characterization of Dust-Fall Samples Collected from Greater Cairo, Egypt.

    PubMed

    Shaltout, Abdallah A; Allam, Mousa A; Mostafa, Nasser Y; Heiba, Zein K

    2016-04-01

    This work aimed to characterize dust-fall samples collected from street's trees in Greater Cairo (GC), Egypt, and its surroundings by different spectroscopic techniques, namely; X-ray diffraction (XRD), attenuated total-reflection Fourier transform infrared (ATR-FTIR), particle-size analyzer, and scanning electron microscopy (SEM) combined with energy dispersive X-ray measurements. Samples were collected from 19 different locations inside and outside of GC. Quantitative phase analysis of the dust-fall samples was performed using the Rietveld method. Results showed that the most frequently observed phases in the dust-fall samples were calcite (CaCO3), dolomite (CaMg(CO3)2), gypsum (CaSO4·2H2O), and quartz (SiO2) with average concentrations of 39 ± 16, 8 ± 7, 22 ± 13, and 33 ± 14 wt%, respectively. The occurrence of these constituents referred to a combination of different anthropogenic and natural sources. The ATR-FTIR results are in good agreements with XRD data of the different observed phases. Based on the SEM and particle-size measurements, quantitative determination of the particle-size distribution was described. It was found that not only the large-sized particles are deposited but also the small-sized ones (PM10 and PM2.5). In addition, the particle size of the collected dust-fall samples varied from 0.1 to 200 µm with an average particle size of 17.36 µm; however, the particle size ranged from 2.5 to 40 µm predominated in all of the dust-fall samples. PMID:26710766

  13. Size separation method for absorption characterization in brown carbon: Application to an aged biomass burning sample

    NASA Astrophysics Data System (ADS)

    Di Lorenzo, Robert A.; Young, Cora J.

    2016-01-01

    The majority of brown carbon (BrC) in atmospheric aerosols is derived from biomass burning (BB) and is primarily composed of extremely low volatility organic carbons. We use two chromatographic methods to compare the contribution of large and small light-absorbing BrC components in aged BB aerosols with UV-vis absorbance detection: (1) size exclusion chromatography (SEC) and (2) reverse phase high-performance liquid chromatography. We observe no evidence of small molecule absorbers. Most BrC absorption arises from large molecular weight components (>1000 amu). This suggests that although small molecules may contribute to BrC absorption near the BB source, analyses of aerosol extracts should use methods selective to large molecular weight compounds because these species may be responsible for long-term BrC absorption. Further characterization with electrospray ionization mass spectrometry (MS) coupled to SEC demonstrates an underestimation of the molecular size determined through MS as compared to SEC.

  14. Probing the Fermi Bubbles in Ultraviolet Absorption: A Spectroscopic Signature of the Milky Way's Biconical Nuclear Outflow

    NASA Astrophysics Data System (ADS)

    Fox, Andrew J.; Bordoloi, Rongmon; Savage, Blair D.; Lockman, Felix J.; Jenkins, Edward B.; Wakker, Bart P.; Bland-Hawthorn, Joss; Hernandez, Svea; Kim, Tae-Sun; Benjamin, Robert A.; Bowen, David V.; Tumlinson, Jason

    2015-01-01

    Giant lobes of plasma extend ?55 above and below the Galactic center, glowing in emission from gamma rays (the Fermi Bubbles) to microwaves and polarized radio waves. We use ultraviolet absorption-line spectra from the Hubble Space Telescope to constrain the velocity of the outflowing gas within these regions, targeting the quasar PDS 456 (l, b = 10.4, +11.2). This sightline passes through a clear biconical structure seen in hard X-ray and gamma-ray emission near the base of the northern Fermi Bubble. We report two high-velocity metal absorption components, at v LSR = -235 and +250 km s-1, which cannot be explained by co-rotating gas in the Galactic disk or halo. Their velocities are suggestive of an origin on the front and back side of an expanding biconical outflow emanating from the Galactic center. We develop simple kinematic biconical outflow models that can explain the observed profiles with an outflow velocity of gsim900 km s-1 and a full opening angle of ?110 (matching the X-ray bicone). This indicates Galactic center activity over the last ?2.5-4.0 Myr, in line with age estimates of the Fermi Bubbles. The observations illustrate the use of UV spectroscopy to probe the properties of swept-up gas venting into the Fermi Bubbles. Based on observations taken under program 13448 of the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555, and under program 14B-299 of the NRAO Green Bank Telescope, which is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

  15. Metal oxide-supported cluster catalysts derived from organometallic precursors: Spectroscopic characterization in reactive environments

    NASA Astrophysics Data System (ADS)

    Lai, Felix Shangchung

    Metals are among the most important catalysts. Catalysis of CO oxidation by metals is important for emissions control and potentially for fuel cell applications. Bimetallic catalysts have found useful applications by improving the selectivity or lifetime over what is attainable with monometallic catalysts. This thesis reports an evaluation of temperature-programmed desorption for characterizing dispersed bimetallic catalysts; characterization of structurally simple site-isolated iridium oxide and rhodium oxide species made from supported clusters; and investigation of site-isolated iridium clusters and rhodium clusters, Ir4 and Rh6, as well as the oxide species formed from them as CO oxidation catalysts. The highly dispersed supported bimetallic catalysts were prepared from organometallic precursors incorporating the oxophilic tungsten bonded to the noble platinum. Site-isolated iridium oxide and rhodium oxide species were made by treatment in O2 of nearly uniform supported metal clusters, synthesized from metal carbonyl precursors, Ir4, Ir6, and Rh6, supported on MgO and on Al2O3. X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy were used to show that ensembles of site-isolated oxide complexes were made from Ir4 and Rh6 clusters supported on MgO; the metal clusters could be reformed from the ensembles. The rhodium samples were found to be active for CO oxidation catalysis, exhibiting light-off behavior at temperatures between 398 and 473 K. The order of activity of the rhodium species is Rh(0) > Rh(I) >> Rh(III), corresponding to zerovalent rhodium clusters, rhodium centers associated with gem-dicarbonyl and oxide species similar to those in the ensembles of oxide complexes, respectively. Light-off behavior was also observed for the iridium samples at temperatures between 473 and 548 K. The oxide species were found to be inactive for CO oxidation catalysis, but zerovalent iridium is active; Ir(I) centers cannot be ruled out as catalytically active species.

  16. Spectroscopic characterization of PET glycolysis and surface molecular orientation of polymers

    NASA Astrophysics Data System (ADS)

    Weir, Michael David

    This dissertation seeks to develop novel polymer characterization techniques using UV and fluorescence spectroscopy. The first portion of the dissertation consists of monitoring the glycolytic depolymerization of poly(ethylene terephthalate), PET, using UV and fluorescence spectroscopy. The primary product of the glycolysis of PET is bis(hydroxyethyl) tereplithalate (BHET), along with other low molecular weight oligomers (degree of polymerization = 1--3). The UV absorption of the glycolized products occurs at 287 nm and is associated with the pi ? pi* transition of the tereplithalate moiety. This absorption band shows a linear increase with reaction time that corresponds to an increase in the concentration of glycolized products. BHET was selected as a model compound to represent the glycolized products and was used to calculate the concentration of glycolized products. When using excitation wavelengths of 300 nm and 340 nm, fluorescence emission spectra of the glycolized products were observed at 350 nm and 380 nm respectively. These emission bands also showed an increase in intensity corresponding to the concentration increase. Again, BHET was used as a model compound to simulate and calculate the concentration of the glycolized products. We determined the overall reaction to be second order and that the reaction rate is strongly dependent on the glycol concentration; an increase in the glycol concentration results in an increase in the reaction rate. The second portion of this dissertation consists of the characterization of surface molecular orientation of poly(ethylene terephthalate) (PET) and Kaptono films by UV reflection dichroism using a specular reflection accessory and a bifurcated fiber optic. The UV reflection peaks for PET and Kapton RTM occur at 257 nm and 310 nm respectively. The orientation function and dichroic ratio calculated using both specular reflection and the fiber optic agreed well with each other. Additionally, correct placement of the polarizer is essential in producing good results. When placed at either the source or detector side of the fiber, there was no evidence of orientation seen. However, placement at the common end shows good agreement with the results from the specular reflection accessory. These different results are a manifestation of the polarization/depolarization characteristics of the fiber optic.

  17. Synthesis, spectroscopic characterization and molecular modeling of a tetranuclear platinum(II) complex with thiazolidine-4-carboxylic acid

    NASA Astrophysics Data System (ADS)

    Corbi, Pedro P.; Formiga, Andr L. B.; Bonk, Fbio A.; Quinto, Frederico A.; Ferraresi, Diego K. D.; Lustri, Wilton R.; Massabni, Antonio C.

    2012-07-01

    The synthesis, spectroscopic characterization and molecular modeling of a novel tetranuclear platinum(II) complex with thiazolidine-4-carboxylic acid (THC) are described. Elemental analysis is consistent with the composition PtCl2C4H7NO2SH2O. Infrared (IR) spectroscopic results and solid-state 13C and 15N nuclear magnetic resonance (NMR) data indicate coordination of the ligand to Pt(II) through the nitrogen and sulfur atoms. The square planar geometry of the platinum(II) complex is completed by chlorine atoms. Density functional theory (DFT) suggests the formation of a tetrameric cluster as the most probable structure, where each THC molecule bridges between two metal centers. The compound is insoluble in water.

  18. Preparation, spectroscopic characterization and energy transfer investigation of iron-chromium diffusion co-doped ZnSe for mid-IR laser applications

    NASA Astrophysics Data System (ADS)

    Wang, XiangYong; Chen, Zhe; Zhang, Lianhan; Jiang, Benxue; Xu, Min; Hong, Jiaqi; Wang, Yaqi; Zhang, Peixiong; Zhang, Long; Hang, Yin

    2016-04-01

    The spectroscopic characterization and energy transfer mechanism of iron-chromium co-doped ZnSe polycrystalline (Cr,Fe:ZnSe) were reported with dimension of 15 mm × 15 mm × 2 mm obtained by controlled post-growth thermal diffusion method. The infrared absorption is characterized by a strong broad-band centered at 1770 nm which can be attributed to the only spin-allowed transition 5T2 → 5E within the 3d4 shell of Cr2+ ions. Photoluminescence spectrum shows a relatively strong broad emission band centered at 4.1 μm with a width of 0.8 μm (FWHM) under 1770 nm excitation at room temperature and reveals effective Cr2+ → Fe2+ energy transfer process. Room temperature photoluminescence decay about 8 μs was measured. All the results indicate that Cr,Fe:ZnSe could achieve laser operation at 3.7-4.5 μm via Cr2+ → Fe2+ energy transfer using a more convenient laser pump source in the near IR region.

  19. Tissue characterization with ballistic photons: counting scattering and/or absorption centres

    NASA Astrophysics Data System (ADS)

    Corral, F.; Strojnik, M.; Paez, G.

    2015-03-01

    We describe a new method to separate ballistic from the scattered photons for optical tissue characterization. It is based on the hypothesis that the scattered photons acquire a phase delay. The photons passing through the sample without scattering or absorption preserve their coherence so they may participate in interference. We implement a Mach-Zehnder experimental setup where the ballistic photons pass through the sample with the delay caused uniquely by the sample indices of refraction. We incorporate a movable mirror on the piezoelectric actuator in the sample arm to detect the amplitude of the modulation term. We present the theory that predicts the path-integrated (or total) concentration of the scattering and absorption centres. The proposed technique may characterize samples with transmission attenuation of ballistic photons by a factor of 10-14.

  20. Atomic absorption spectroscopic, conductometric and colorimetric methods for determination of fluoroquinolone antibiotics using ammonium reineckate ion-pair complex formation

    NASA Astrophysics Data System (ADS)

    Ragab, Gamal H.; Amin, Alaa S.

    2004-03-01

    Three accurate, rapid and simple atomic absorption spectrometric, conductometric and colorimetric methods were developed for the determination of norfloxacin (NRF), ciprofloxacin (CIP), ofloxacin (OFL) and enrofloxacin (ENF). The proposed methods depend upon the reaction of ammonium reineckate with the studied drugs to form stable precipitate of ion-pair complexes, which was dissolved in acetone. The pink coloured complexes were determined either by AAS or colorimetrically at ?max 525 nm directly using the dissolved complex. Using conductometric titration, the studied drugs could be evaluated in 50% (v/v) acetone in the range 5.0-65, 4.0-48, 5.0-56 and 6.0-72 ?g ml -1 of NRF, CPF, OFL and ENF, respectively. The optimizations of various experimental conditions were described. The results obtained showed good recoveries of 99.151.15, 99.301.40, 99.601.50, and 99.001.25% with relative standard deviations of 0.81, 1.06, 0.97, and 0.69% for NRF, CPF, OFL, and ENF, respectively. Applications of the proposed methods to representative pharmaceutical formulations are successfully presented.

  1. Different speciation for bromine in brown and red algae, revealed by in vivo X-ray absorption spectroscopic studies.

    PubMed

    Küpper, Frithjof C; Leblanc, Catherine; Meyer-Klaucke, Wolfram; Potin, Philippe; Feiters, Martin C

    2014-08-01

    Members of various algal lineages are known to be strong producers of atmospherically relevant halogen emissions, that is a consequence of their capability to store and metabolize halogens. This study uses a noninvasive, synchrotron-based technique, X-ray absorption spectroscopy, for addressing in vivo bromine speciation in the brown algae Ectocarpus siliculosus, Ascophyllum nodosum, and Fucus serratus, the red algae Gracilaria dura, G. gracilis, Chondrus crispus, Osmundea pinnatifida, Asparagopsis armata, Polysiphonia elongata, and Corallina officinalis, the diatom Thalassiosira rotula, the dinoflagellate Lingulodinium polyedrum and a natural phytoplankton sample. The results highlight a diversity of fundamentally different bromine storage modes: while most of the stramenopile representatives and the dinoflagellate store mostly bromide, there is evidence for Br incorporated in nonaromatic hydrocarbons in Thalassiosira. Red algae operate various organic bromine stores - including a possible precursor (by the haloform reaction) for bromoform in Asparagopsis and aromatically bound Br in Polysiphonia and Corallina. Large fractions of the bromine in the red algae G. dura and C. crispus and the brown alga F. serratus are present as Br(-) defects in solid KCl, similar to what was reported earlier for Laminaria parts. These results are discussed according to different defensive strategies that are used within algal taxa to cope with biotic or abiotic stresses. PMID:26988449

  2. The chemical environment of iron in mineral fibres. A combined X-ray absorption and Mssbauer spectroscopic study.

    PubMed

    Pollastri, Simone; D'Acapito, Francesco; Trapananti, Angela; Colantoni, Ivan; Andreozzi, Giovanni B; Gualtieri, Alessandro F

    2015-11-15

    Although asbestos represents today one of the most harmful contaminant on Earth, in 72% of the countries worldwide only amphiboles are banned while controlled use of chrysotile is allowed. Uncertainty on the potential toxicity of chrysotile is due to the fact that the mechanisms by which mineral fibres induces cyto- and geno-toxic damage are still unclear. We have recently started a long term project aimed at the systematic investigation of the crystal-chemistry, bio-interaction and toxicity of the mineral fibres. This work presents a systematic structural investigation of iron in asbestos and erionite (considered the most relevant mineral fibres of social and/or economic-industrial importance) using synchrotron X-ray absorption and Mssbauer spectroscopy. In all investigated mineral fibres, iron in the bulk structure is found in octahedral sites and can be made available at the surface via fibre dissolution. We postulate that the amount of hydroxyl radicals released by the fibers depends, among other factors, upon their dissolution rate; in relation to this, a ranking of ability of asbestos fibres to generate hydroxyl radicals, resulting from available surface iron, is advanced: amosite > crocidolite ? chrysotile > anthophyllite > tremolite. Erionite, with a fairly high toxicity potential, contains only octahedrally coordinated Fe(3+). Although it needs further experimental evidence, such available surface iron may be present as oxide nanoparticles coating and can be a direct cause of generation of hydroxyl radicals when such coating dissolves. PMID:26073382

  3. X-ray absorption spectroscopic evidence for the complexation of Hg(II) by reduced sulfur in soil humic substances

    SciTech Connect

    Xia, K.; Skyllberg, U.L.; Bleam, W.F.; Helmke, P.A.; Bloom, P.R.; Nater, E.A.

    1999-01-15

    Analysis of Hg(II) complexed by a soil humic acid (HA) using synchrotron-based X-ray absorption spectroscopy (XAS) revealed the importance of reduces sulfur functional groups (thiol (R-SH) and disulfide (R-SS-R)/disulfane (R-SSH)) in humic substances in the complexation of Hg(II). A two-coordinate binding environment with one oxygen atom and one sulfur atom at distances of 2.02 and 2.38 {angstrom}, respectively, was found in the first coordination shell of Hg(II) complexed by humic acid. Model calculations show that a second coordination sphere could contain one carbon atom and a second sulfur atom at 2.78 and 2.93 {angstrom}, respectively. This suggests that in addition to thiol S, disulfide/disulfane S may be involved with the complexation of Hg(II) in soil organic matter. The appearance of carbon atom in the second coordination shell suggests that one O-containing ligand such as carboxyl and phenol ligands rather than H{sub 2}O molecule is bound to the Hg(II). The involvement of oxygen ligand in addition to the reduced S ligands in the complexation of Hg(II) is due to the low density of reduced S ligands in humic substances. The XAS results from this experiment provided direct molecular level evidence for the preference of reduced S functional groups over oxygen ligands by Hg(II) in the complexation with humic substances.

  4. X-ray absorption spectroscopic study of sodium iodide and iodine mediators in a solid-state supercapacitor

    NASA Astrophysics Data System (ADS)

    Mansour, Azzam N.; Zhou, Juanjuan; Zhou, Xiangyang

    2014-01-01

    In situ X-ray absorption spectroscopy was used to provide the redox states of the NaI/I2 mediators in an all-solid-state mediator-enhanced supercapacitor during the charge/discharge processes. Results show that in the charge process from -0.08 (open-circuit voltage (OCV)) to 0.80 V at constant current of 5 mA, all of the I- ions were oxidized to I2. However, in the discharge process from +0.80 V to OCV at constant current of -5 mA, only I3- ions were detected indicating that the I2 molecules were reduced to I3- ions. Upon a negative polarization from OCV to -0.80 V at constant current of -5 mA, the I3- ions were reduced to I- ions. Based on combined in situ XAS and cyclic voltammetry data, we show that the I-/I2 redox couple proceeds via the formation of I3- ions as an intermediate step.

  5. Compressed shell conditions extracted from spectroscopic analysis of Ti K-shell absorption spectra with evaluation of line self-emission

    SciTech Connect

    Johns, H. M.; Mancini, R. C.; Hakel, P.; Nagayama, T.; Smalyuk, V. A.; Regan, S. P.; Delettrez, J.

    2014-08-15

    Ti-doped tracer layers embedded in the shell at varying distances from the fuel-shell interface serve as a spectroscopic diagnostic for direct-drive experiments conducted at OMEGA. Detailed modeling of Ti K-shell absorption spectra produced in the tracer layer considers n?=?12 transitions in F- through Li-like Ti ions in the 44004800?eV range, both including and excluding line self-emission. Testing the model on synthetic spectra generated from 1-D LILAC hydrodynamic simulations reveals that the model including self-emission best reproduces the simulation, while the model excluding self-emission overestimates electron temperature T{sub e} and density N{sub e} to a higher degree for layers closer to the core. The prediction of the simulation that the magnitude of T{sub e} and duration of Ti absorption will be strongly tied to the distance of the layer from the core is consistent with the idea that regions of the shell close to the core are more significantly heated by thermal transport out of the hot dense core, but more distant regions are less affected by it. The simulation predicts more time variation in the observed T{sub e}, N{sub e} conditions in the compressed shell than is observed in the experiment, analysis of which reveals conditions remain in the range T{sub e}?=?400600?eV and N{sub e}?=?3.010.0??10{sup 24} cm{sup ?3} for all but the most distant Ti-doped layer, with error bars ?5% T{sub e} value and ?10% N{sub e} on average. The T{sub e}, N{sub e} conditions of the simulation lead to a greater degree of ionization for zones close to the core than occurs experimentally, and less ionization for zones far from the core.

  6. Spectroscopic and structural characterization of reduced technetium species in acetate media

    SciTech Connect

    Mausolf, Edward; Poineau, Frederic; Droessler, Janelle; Czerwinski, Kenneth R.

    2011-11-17

    The reduction of ammonium pertechnetate by sodium borohydride in 0.1 M NaOH/glacial acetic acid has been studied. The reduction products (solids and solutions) have been characterized by UV-Visible spectroscopy, Scanning Electron Microscopy/Energy-dispersive X-ray emission spectroscopy (SEM/EDS), and X-ray absorption fine structure (XAFS) spectroscopy. UV-Visible spectra of the solution, after reduction, exhibit bands at 350 and 500 nm that have been attributed to the formation of polymeric Tc(IV) species. SEM/EDS on the solid (X-ray amorphous) indicates the absence of metallic Tc and the presence of oxygen. EXAFS measurements further indicate that the precipitate exhibits a [Tc({mu}-O){sub 2}Tc] core structure. XANES is consistent with the formation of Tc(III) and/or Tc(IV). Results infer that reduction of aqueous Tc(VII) by borohydride in the presence of acetic acid does not produce metallic Tc, but a mixture of various oxidation states of Tc near Tc(III) and Tc(IV).

  7. Infrared spectroscopic, x-ray, and nanoscale characterization of strontium titanate thin films

    SciTech Connect

    Webb, J.D.; Moutinho, H.R.; Kazmerski, L.L.; Mueller, C.H.; Rivkin, T.V.; Treece, R.E.; Dalberth, M.; Rogers, C.T.

    1996-04-01

    Attenuated total reflectance (ATR) measurements were performed using Fourier transform infrared (FTIR) spectroscopy in the ATR mode with a thallium iodobromide (KRS-5) crystal to measure the frequencies of the {nu}{sub 3} and {nu}{sub 4} phonon absorption bands in thin strontium titanate films deposited on single-crystal yttrium-barium copper oxide (YBCO), lanthanum aluminate, magnesium oxide, and strontium titanate substrates. The KRS-5 crystal enabled FTIR-ATR measurements to be made at frequencies above 400 cm{sup {minus}1}. Atomic force microscopy (AFM) and X-ray diffraction (XRD) measurements were also made to further characterize the films. The measurements were repeated on single-crystal specimens of strontium titanate and the substrates for comparison. Softening in the frequency of the {nu}{sub 4} transverse optical phonon in the lattice- mismatched films below the established value of 544 cm{sup {minus}1} is indicative of the highly textured, polycrystalline ceramic nature of the films and is consistent with the XRD and AFM results.

  8. Infrared spectroscopic, x-ray, and nanoscale characterization of strontium titanate thin films

    SciTech Connect

    Webb, J.D.; Moutinho, H.R.; Kazmerski, L.L.; Mueller, C.H.; Rivkin, T.V.; Treece, R.E.; Dalberth, M.; Rogers, C.T.

    1996-06-01

    Attenuated total reflectance (ATR) measurements were performed using Fourier transform infrared (FTIR) spectroscopy in the ATR mode with a thallium iodobromide (KRS-5) crystal to measure the frequencies of the v{sub 3} and v{sub 4} phonon absorption bands in thin Sr titanate films deposited on single-crystal Y-Ba Cu oxide (YBCO), La aluminate, Mg oxide, and Sr titanate substrates. The KRS-5 crystal enabled FTIR-ATR measurements at frequencies above 400 cm{sup -1}. Atomic force microscopy (AFM) and x-ray diffraction (XRD) measurements were also made to further characterize the films. The measurements were repeated on single-crystal specimens of Sr titanate and the substrates for comparison. Softening in the frequency of the v{sub 4} transverse optical phonon in the lattice-mismatched films below the established value of 544 cm{sup -1} is indicative of the highly textured, polycrystalline ceramic nature of the films and is consistent with the XRD and AFM results.

  9. X-ray photoelectron and optical absorption spectroscopic studies on the dye chlorodiane blue, used as a carrier generation molecule in organic photoconductors

    SciTech Connect

    Pacansky, J.; Waltman, R.J.

    1992-07-01

    The dye chlorodiane blue, used as a carrier generation molecule in organic photoconductors, is characterized via optical absorption and X-ray photoelectron spectroscopy, and the results are interpreted on the basis of ab initio quantum mechanical molecular models. These data indicate that chlorodiane blue exists as azo-enol and hydrazone-quinone chemical structures and it is the hydrazone-quinone form that provides the higher xerographic gain in electrophotographic applications. Optimized geometries, atomic charges, and molecular orbital plots and energies are reported for both the azo-enol and hydrazone-quinone forms of chlorodiane blue. The two structural forms of the dye are experimentally distinguishable via both optical absorption and X-ray photoelectron spectroscopy, and the wavelength and chemical shifts, respectively, are interpreted via the theoretical results. 29 refs., 9 figs., 4 tabs.

  10. An x-ray absorption spectroscopic study of the electronic structure and bonding of rare-earth orthoferrites.

    PubMed

    Hayes, J R; Grosvenor, A P

    2011-11-23

    Rare-earth orthoferrites, REFeO? (RE D rare earth; Y), are tremendously adaptable compounds that are being investigated for use in a wide variety of applications including gas sensors, vehicle catalytic converters, and solid-oxide fuel cells. They also exhibit interesting magnetic properties such as high-temperature antiferromagnetism, making them useful for data storage applications. The compounds adopt a distorted perovskite-type structure where the tilt angle of the octahedra increases (Fe-O-Fe bond angle decreases) as the size of the rare-earth atom decreases. Despite intensive study of the physical properties of these compounds, very few studies have investigated how the bonding and electronic structure of these systems change with substitution of the RE. X-ray absorption near-edge spectroscopy (XANES) is a technique well-suited for such a study, and, in view of this, Fe L-, Fe K- and O K-edge spectra from a series of REFeO? compounds (RE D La, Pr, Nd, Sm, Eu, Gd, Ho, Yb, Y) have been collected, and are presented here. Fe L-edge spectra show that Fe is octahedrally coordinated and that the Fe-centered octahedra do not appear to distort with changes in the identity of the RE. The Fe K-edge spectra contain an intersite hybrid peak, which is an ill-studied feature that is attributed to non-local transitions of 1s electrons to 3d states on the next-nearest-neighbor atom that are hybridized with 4p states on the absorbing atom through O 2p states. In this study, it is shown that the intensity of this feature is strongly dependent on the Fe-O-Fe bond angle; the lower the Fe-O-Fe bond angle, the less intense the intersite hybrid peak is. PMID:22056809

  11. Optical absorption of Zn(V,Al)O thin films studied by spectroscopic ellipsometry from 1 to 6 eV

    NASA Astrophysics Data System (ADS)

    Sayari, Amor; El Mir, Lassaad; Al-Heniti, Saleh; Al-Harbi, Talal; Yaghmour, Saud Jamil; Abdullah Al-Ghamdi, Ahmad

    2013-06-01

    Aerogel nanoparticles prepared with various Al concentrations were used as a target for the deposition of (V,Al) co-doped ZnO films by rf-magnetron sputtering on glass substrates. The influence of Al content on the structural and the optical properties of the Zn(V,Al)O films was investigated by X-ray diffraction and spectroscopic ellipsometry (SE). It is found that all films exhibit one high intensity (0 0 2) peak, indicating that they have c-axis preferred orientation due to self-texturing mechanism. SE measurements, used to determine the complex pseudo dielectric functions, were carried out at room temperature in the 1-6 eV photon energy region. The excitonic edge of the fundamental band gap (E0) transition in the imaginary part of the dielectric function of the Zn(V,Al)O films is observed around 3.5 eV and shows a dependence on the Al content. The E0 absorption edge of the Zn0.9-x V0.1AlxO alloys shows a blueshift from that of pure ZnO, reaching 389 meV for x = 0.02. This blueshift is interpreted by the Burstein-Moss effect. By analyzing the dielectric function, reduced effective mass m* of the Zn0.9-x V0.1AlxO alloy is extracted and shows good agreement with literature values.

  12. Synthesis and spectroscopic characterization of super-stable rhenium(V)porphyrins

    NASA Astrophysics Data System (ADS)

    Bichan, N. G.; Tyulyaeva, E. Yu.; Khodov, I. A.; Lomova, T. N.

    2014-03-01

    The preparation of rhenium(V) porphyrin complexes {μ-oxo-bis[(oxo)(5,10,15,20-tetraphenyl-21H,23H-porphinato)rhenium(V)] [OReTPP]2O (1), (oxo)(phenoxo)(2,3,7,8,12,13,17,18-octaethyl-5-monophenyl-21H,23H-porphinato)rhenium(V) ORe(PhO)MPOEP (2), (cloro)(oxo)(2,3,7,8,12,13,17,18-octaethyl-5,15-diphenyl-21H,23H-porphinato)rhenium(V) ORe(Cl)5,15DPOEP (4), and (oxo)(phenoxo)(2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphinato)rhenium(V) ORe(PhO)OEP (5)} by the interaction of H2ReCl6 with corresponding porphyrin in boiling phenol is described. (Cloro)(oxo)(2,3,7,8,12,13,17,18-octaethyl-5-monophenyl-21H,23H-porphinato)rhenium(V) ORe(Cl)MPOEP (3) and (oxo)(chloro)(2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphinato)rhenium(V) ORe(Cl)OEP (6) have been prepared by the reaction of axial-ligand substitution from (2) and (5), respectively. Compounds (2-4) were newly synthesized. Characterization of the compounds (1-6) reported herein was made mainly by UV-Visible, IR, 1Н NMR, 1H1H 2D COSY, 1H1H 2D DOSY, 1H1H 2D ROESY, 1H1H 2D TOCSY spectroscopic techniques and elemental analysis. The stability of the complexes in solutions when exposed to strong acids at the presence of atmospheric oxygen has been estimated. Compounds (2-4) and (6) show them super-stable since they do not undergo dissociation along MN bonds in concentrated H2SO4 under heating up to 363 K. Compounds (3) and (4) undergo one-electron oxidation to form stable π-cation radicals ORe(HSO)P under these conditions. The products of the reaction between all studied porphyrins and concentrated H2SO4 were isolated in CHCl3 by reprecipitation onto ice and proved to be rhenium(V) complexes ORe(HSO4)P.

  13. Crystal structure, complexation, spectroscopic characterization and antimicrobial evaluation of 3,4-dihydroxybenzylidene isonicotinyl-hydrazone.

    PubMed

    Jeragh, Bakir; Ali, Mayada S; El-Asmy, Ahmed A

    2015-06-15

    A single crystal of 3,4-dihydroxybenzylidene isonicotinylhydrazone, HBINH, has been grown and solved by X-ray crystallography. The VO(2+), Zr(4+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+) and Pd(2+) complexes of HBINH have been prepared and spectroscopically characterized. The data confirmed the formulae [Co(HBINH)(H2O)Cl]ClH2O, [Pd(HBINH)Cl2], [Zn(HBINH)2Cl2], [Cd(HBINH)(H2O)2Cl2]1H2O, [(VO)2(HBINH-3H)(OH)(H2O)], [Ni2(HBINH)(H2O)6Cl2]Cl2, [Cu2(HBINH-3H)(H2O)2(OAc)]3H2O, [Zr2(HBINH-3H)Cl4]Cl, [Hg2(HBINH)Cl4] and the dimer {[Cu(HBINH)Cl]Cl}2. Most of the complexes have intense colors and high melting points and some are electrolytes in DMSO solution. The ligand behaves as a neutral bidentate in the Co(II), Cu(II), Pd(II), Zn(II) and Cd(II) complexes; dibasic tetradentate in [Ni2(HBINH)(H2O)6Cl2]Cl2 and tribasic tetradentate in [Cu2(HBINH-3H)(OAc)]5H2O, [(VO)2(HBINH-3H)(OH)(H2O)] and [Zr2(HBINH-3H)Cl4]Cl by the loss of 3H(+) due to the deprotonation of the two hydroxyl groups and the enolization of the amide (OCNH) group. A tetrahedral geometry was proposed for the Co(II), Cu(II), Zn(II) and Hg(II) complexes; square-planar for the Pd(II) complex; square-pyramid for the VO(2+) complex and octahedral for the Ni(II) and Cd(II) complexes. The complexes [Cd(HBINH)(H2O)2Cl2]1H2O, [(VO)2(HBINH-3H)(OH)(H2O)] and [Cu2(HBINH-3H)-(H2O)2(OAc)]3H2O have activities against Bacillus sp. M3010, Candida albicans, Escherichia coli, Staphylococcus aureus and Slamonella sp. PA393. PMID:25791887

  14. Crystal structure, complexation, spectroscopic characterization and antimicrobial evaluation of 3,4-dihydroxybenzylidene isonicotinyl-hydrazone

    NASA Astrophysics Data System (ADS)

    Jeragh, Bakir; Ali, Mayada S.; El-Asmy, Ahmed A.

    2015-06-01

    A single crystal of 3,4-dihydroxybenzylidene isonicotinylhydrazone, HBINH, has been grown and solved by X-ray crystallography. The VO2+, Zr4+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+ and Pd2+ complexes of HBINH have been prepared and spectroscopically characterized. The data confirmed the formulae [Co(HBINH)(H2O)Cl]Cl·H2O, [Pd(HBINH)Cl2], [Zn(HBINH)2Cl2], [Cd(HBINH)(H2O)2Cl2]·1½H2O, [(VO)2(HBINH-3H)(OH)(H2O)], [Ni2(HBINH)(H2O)6Cl2]Cl2, [Cu2(HBINH-3H)(H2O)2(OAc)]·3H2O, [Zr2(HBINH-3H)Cl4]Cl, [Hg2(HBINH)Cl4] and the dimer {[Cu(HBINH)Cl]Cl}2. Most of the complexes have intense colors and high melting points and some are electrolytes in DMSO solution. The ligand behaves as a neutral bidentate in the Co(II), Cu(II), Pd(II), Zn(II) and Cd(II) complexes; dibasic tetradentate in [Ni2(HBINH)(H2O)6Cl2]Cl2 and tribasic tetradentate in [Cu2(HBINH-3H)(OAc)]·5H2O, [(VO)2(HBINH-3H)(OH)(H2O)] and [Zr2(HBINH-3H)Cl4]Cl by the loss of 3H+ due to the deprotonation of the two hydroxyl groups and the enolization of the amide (Odbnd CNH) group. A tetrahedral geometry was proposed for the Co(II), Cu(II), Zn(II) and Hg(II) complexes; square-planar for the Pd(II) complex; square-pyramid for the VO2+ complex and octahedral for the Ni(II) and Cd(II) complexes. The complexes [Cd(HBINH)(H2O)2Cl2]·1½H2O, [(VO)2(HBINH-3H)(OH)(H2O)] and [Cu2(HBINH-3H)-(H2O)2(OAc)]·3H2O have activities against Bacillus sp. M3010, Candida albicans, Escherichia coli, Staphylococcus aureus and Slamonella sp. PA393.

  15. Calibration method for spectroscopic systems

    DOEpatents

    Sandison, D.R.

    1998-11-17

    Calibration spots of optically-characterized material placed in the field of view of a spectroscopic system allow calibration of the spectroscopic system. Response from the calibration spots is measured and used to calibrate for varying spectroscopic system operating parameters. The accurate calibration achieved allows quantitative spectroscopic analysis of responses taken at different times, different excitation conditions, and of different targets. 3 figs.

  16. Nanoflaky MnO2/functionalized carbon nanotubes for supercapacitors: an in situ X-ray absorption spectroscopic investigation

    NASA Astrophysics Data System (ADS)

    Chang, Han-Wei; Lu, Ying-Rui; Chen, Jeng-Lung; Chen, Chi-Liang; Lee, Jyh-Fu; Chen, Jin-Ming; Tsai, Yu-Chen; Chang, Chien-Min; Yeh, Ping-Hung; Chou, Wu-Ching; Liou, Ya-Hsuan; Dong, Chung-Li

    2015-01-01

    The surfaces of acid- and amine-functionalized carbon nanotubes (C-CNT and N-CNT) were decorated with MnO2 nanoflakes as supercapacitors by a spontaneous redox reaction. C-CNT was found to have a lower edge plane structure and fewer defect sites than N-CNT. MnO2/C-CNT with a highly developed surface area exhibited favorable electrochemical performance. To determine the atomic/electronic structures of the MnO2/functionalized CNTs (MnO2/C-CNT and MnO/N-CNT) during the charge/discharge process, in situ X-ray absorption spectroscopy (XAS) measurements were made at the Mn K-edge. Both C-CNT and N-CNT are highly conductive. The effect of the scan rate on the capacitance behavior was also examined, revealing that the ?* state of CNT and the size of the tunnels in pseudo-capacitor materials (which facilitate conduction and the transport of electrolyte ions) are critical for the capacitive performance, and their role depends on the scan rate. In the slow charge/discharge process, MnO2/N-CNT has a more symmetrical rectangular cyclic voltammetry (CV) curve. In the fast charge/discharge process, MnO2/C-CNT with a highly developed surface provides fast electronic and ionic channels that support a reversible faradaic redox reaction between MnO2 nanoflakes and the electrolyte, significantly enhancing its capacitive performance over that of MnO2/N-CNT. The MnO2/C-CNT architecture has great potential for supercapacitor applications. The information that was obtained herein helps to elucidate CNT surface modification and the design of the MnO2/functionalized CNT interface with a view for the further development of supercapacitors. This work, and especially the combination of CV with in situ XAS measurements, will be of value to readers with an interest in nanomaterial, nanotechnology and their applications in energy storage.The surfaces of acid- and amine-functionalized carbon nanotubes (C-CNT and N-CNT) were decorated with MnO2 nanoflakes as supercapacitors by a spontaneous redox reaction. C-CNT was found to have a lower edge plane structure and fewer defect sites than N-CNT. MnO2/C-CNT with a highly developed surface area exhibited favorable electrochemical performance. To determine the atomic/electronic structures of the MnO2/functionalized CNTs (MnO2/C-CNT and MnO/N-CNT) during the charge/discharge process, in situ X-ray absorption spectroscopy (XAS) measurements were made at the Mn K-edge. Both C-CNT and N-CNT are highly conductive. The effect of the scan rate on the capacitance behavior was also examined, revealing that the ?* state of CNT and the size of the tunnels in pseudo-capacitor materials (which facilitate conduction and the transport of electrolyte ions) are critical for the capacitive performance, and their role depends on the scan rate. In the slow charge/discharge process, MnO2/N-CNT has a more symmetrical rectangular cyclic voltammetry (CV) curve. In the fast charge/discharge process, MnO2/C-CNT with a highly developed surface provides fast electronic and ionic channels that support a reversible faradaic redox reaction between MnO2 nanoflakes and the electrolyte, significantly enhancing its capacitive performance over that of MnO2/N-CNT. The MnO2/C-CNT architecture has great potential for supercapacitor applications. The information that was obtained herein helps to elucidate CNT surface modification and the design of the MnO2/functionalized CNT interface with a view for the further development of supercapacitors. This work, and especially the combination of CV with in situ XAS measurements, will be of value to readers with an interest in nanomaterial, nanotechnology and their applications in energy storage. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr06439a

  17. Accurate structural and spectroscopic characterization of prebiotic molecules: The neutral and cationic acetyl cyanide and their related species

    NASA Astrophysics Data System (ADS)

    Bellili, A.; Linguerri, R.; Hochlaf, M.; Puzzarini, C.

    2015-11-01

    In an effort to provide an accurate structural and spectroscopic characterization of acetyl cyanide, its two enolic isomers and the corresponding cationic species, state-of-the-art computational methods, and approaches have been employed. The coupled-cluster theory including single and double excitations together with a perturbative treatment of triples has been used as starting point in composite schemes accounting for extrapolation to the complete basis-set limit as well as core-valence correlation effects to determine highly accurate molecular structures, fundamental vibrational frequencies, and rotational parameters. The available experimental data for acetyl cyanide allowed us to assess the reliability of our computations: structural, energetic, and spectroscopic properties have been obtained with an overall accuracy of about, or better than, 0.001 , 2 kcal/mol, 1-10 MHz, and 11 cm-1 for bond distances, adiabatic ionization potentials, rotational constants, and fundamental vibrational frequencies, respectively. We are therefore confident that the highly accurate spectroscopic data provided herein can be useful for guiding future experimental investigations and/or astronomical observations.

  18. Accurate structural and spectroscopic characterization of prebiotic molecules: The neutral and cationic acetyl cyanide and their related species.

    PubMed

    Bellili, A; Linguerri, R; Hochlaf, M; Puzzarini, C

    2015-11-14

    In an effort to provide an accurate structural and spectroscopic characterization of acetyl cyanide, its two enolic isomers and the corresponding cationic species, state-of-the-art computational methods, and approaches have been employed. The coupled-cluster theory including single and double excitations together with a perturbative treatment of triples has been used as starting point in composite schemes accounting for extrapolation to the complete basis-set limit as well as core-valence correlation effects to determine highly accurate molecular structures, fundamental vibrational frequencies, and rotational parameters. The available experimental data for acetyl cyanide allowed us to assess the reliability of our computations: structural, energetic, and spectroscopic properties have been obtained with an overall accuracy of about, or better than, 0.001 , 2 kcal/mol, 1-10 MHz, and 11 cm(-1) for bond distances, adiabatic ionization potentials, rotational constants, and fundamental vibrational frequencies, respectively. We are therefore confident that the highly accurate spectroscopic data provided herein can be useful for guiding future experimental investigations and/or astronomical observations. PMID:26567669

  19. Vibrational spectroscopic methods to characterize the bionanoparticles originating from newly developed self-forming synthetic PEGylated lipids (QuSomes)

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

    Vibrational spectroscopy has been used to elucidate the temperature dependence of structural and conformational changes in lipids and liposomes. In this work, the thermal properties of lipid-based nanovesicles originating from a newly developed self-forming synthetic PEGylated lipids has been investigated by variable-temperature Fourier-transform infrared (FTIR) absorption and Raman spectroscopic methods. Thermally-induced changes in infrared and Raman spectra of these artificial lipid based nanovesicles composed of 1,2-dimyristoyl-rac-glycerol-3-dodecaethylene glycol (GDM-12) and 1,2-distearoyl-rac-glycerol-3-triicosaethylene glycol (GDS-23) were acquired by using a thin layered FTIR spectrometer in conjunction with a unique custom built temperature-controlled demountable liquid cell and variable-temperature controlled Raman microscope, respectively. The lipids under consideration have long hydrophobic acyl chains and contain various units of hydrophilic polyethylene glycol headgroups. In contrast to conventional phospholipids, this new kind of lipid is forming liposomes or nanovesicles spontaneously upon hydration, without supplying external activation energy. We have found that the thermal stability of such PEGylated lipids and nanovesicles differs greatly depending upon the acyl chain-lengths as well as associated head group units. However, the thermal behavior observed from both spectroscopic vibrational techniques are in good agreement.

  20. Synthesis, conformational and spectroscopic characterization of monomeric styrene derivatives having pendant p-substituted benzylic ether groups.

    PubMed

    Cinar, Mehmet; Ozcan, Levent; Karabacak, Mehmet; Erol, Ibrahim

    2013-07-01

    Three derivatives of styrene monomer, 4-chlorophenyl-4-vinylbenzyl ether (I), 4-methoxyphenyl-4-vinylbenzyl ether (II) and 4-ethylphenyl-4-vinylbenzyl ether (III) were synthesized. The synthesized two novel compounds (I and III) and one with undefined structural features were identified by experimental spectroscopic techniques and density functional approach. The optimized geometrical structure, vibrational and electronic transitions along with chemical shifts of those compounds were presented in this study. The vibrational spectra of investigated compounds were recorded in solid state with FT-IR spectrometry in the range of 4000-400 cm(-1). The computational vibrational wavenumbers and also ground state equilibrium conformations were carried out by using density functional method with 6-311++G(d,p) basis set. Assignments of the fundamental vibrational modes were examined on the basis of the measured data and total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. Isotropic chemical shift of hydrogen and carbon nuclei were investigated via observed (1)H and (13)C NMR spectra in deuterated DMSO solution and predicted data applied with gauge-invariant atomic orbitals (GIAOs) method. The UV absorption spectra of monomers were observed in the range of 200-800 nm in ethanol, and time dependent DFT method was used to obtain the electronic properties. A detailed description of spectroscopic behaviors of compound was given based on the comparison of experimental measurements and theoretical computations. PMID:23608133

  1. Synthesis, conformational and spectroscopic characterization of monomeric styrene derivatives having pendant p-substituted benzylic ether groups

    NASA Astrophysics Data System (ADS)

    Cinar, Mehmet; Ozcan, Levent; Karabacak, Mehmet; Erol, Ibrahim

    2013-07-01

    Three derivatives of styrene monomer, 4-chlorophenyl-4-vinylbenzyl ether (I), 4-methoxyphenyl-4-vinylbenzyl ether (II) and 4-ethylphenyl-4-vinylbenzyl ether (III) were synthesized. The synthesized two novel compounds (I and III) and one with undefined structural features were identified by experimental spectroscopic techniques and density functional approach. The optimized geometrical structure, vibrational and electronic transitions along with chemical shifts of those compounds were presented in this study. The vibrational spectra of investigated compounds were recorded in solid state with FT-IR spectrometry in the range of 4000-400 cm-1. The computational vibrational wavenumbers and also ground state equilibrium conformations were carried out by using density functional method with 6-311++G(d,p) basis set. Assignments of the fundamental vibrational modes were examined on the basis of the measured data and total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. Isotropic chemical shift of hydrogen and carbon nuclei were investigated via observed 1H and 13C NMR spectra in deuterated DMSO solution and predicted data applied with gauge-invariant atomic orbitals (GIAOs) method. The UV absorption spectra of monomers were observed in the range of 200-800 nm in ethanol, and time dependent DFT method was used to obtain the electronic properties. A detailed description of spectroscopic behaviors of compound was given based on the comparison of experimental measurements and theoretical computations.

  2. Purification and spectroscopic characterization of photosystem II reaction center complexes isolated with or without Triton X-100.

    PubMed

    Eijckelhoff, C; van Roon, H; Groot, M L; van Grondelle, R; Dekker, J P

    1996-10-01

    The pigment composition of the isolated photosystem II reaction center complex in its most stable and pure form currently is a matter of considerable debate. In this contribution, we present a new method based on a combination of gel filtration chromatography and diode array detection to analyze the composition of photosystem II reaction center preparations. We show that the method is very sensitive for the detection of contaminants such as the core antenna protein CP47, pigment-free and denatured reaction center proteins, and unbound chlorophyll and pheophytin molecules. We also present a method by which the photosystem II reaction center complex is highly purified without using Triton X-100, and we show that in this preparation the contamination with CP47 is less than 0.1%. The results strongly indicate that the photosystem II reaction center complex in its most stable and pure form binds six chlorophyll a, two pheophytin a, and two beta-carotene molecules and that the main effect of Triton X-100 is the extraction of beta-carotene from the complex. Analysis of 4 K absorption and emission spectra indicates that the spectroscopic properties of this preparation are similar to those obtained by a short Triton X-100 treatment. In contrast, preparations obtained by long Triton X-100 treatment show decreased absorption of the shoulder at 684 nm in the 4 K absorption spectrum and an increased number of pigments that trap excitation energy at very low temperatures. We conclude that the 684 nm shoulder in the 4 K absorption spectrum should at least in part be attributed to the primary electron donor of photosystem II. PMID:8841130

  3. Spectroscopic Characterization and Reactivity of Triplet and Quintet Iron(IV) Oxo Complexes in the Gas Phase

    PubMed Central

    Andris, Erik; Jašík, Juraj; Gómez, Laura

    2016-01-01

    Abstract Closely structurally related triplet and quintet iron(IV) oxo complexes with a tetradentate aminopyridine ligand were generated in the gas phase, spectroscopically characterized, and their reactivities in hydrogen‐transfer and oxygen‐transfer reactions were compared. The spin states were unambiguously assigned based on helium tagging infrared photodissociation (IRPD) spectra of the mass‐selected iron complexes. It is shown that the stretching vibrations of the nitrate counterion can be used as a spectral marker of the central iron spin state. PMID:26878833

  4. New 1,2,4-triazole-based azo-azomethine dyes. Part I: synthesis, characterization and spectroscopic studies.

    PubMed

    Khanmohammadi, Hamid; Erfantalab, Malihe

    2012-02-01

    Four new 1,2,4-triazole-based azo-azomethine dyes were synthesized via condensation of 3,5-diamino-1,2,4-triazole with azo-coupled o-vanillin precursors. The prepared dyes were characterized by IR, UV-vis and (1)H NMR spectroscopic methods as well as elemental analyses. Thermal properties of the prepared dyes were examined by thermogravimetric analysis. Results indicated that the framework of the dyes was stable up to 225 °C. Also, the influence of various factors including time and mixed DMSO/EtOH solution on UV-vis spectra of the dyes were investigated. PMID:22100733

  5. New 1,2,4-triazole-based azo-azomethine dyes. Part I: Synthesis, characterization and spectroscopic studies

    NASA Astrophysics Data System (ADS)

    Khanmohammadi, Hamid; Erfantalab, Malihe

    2012-02-01

    Four new 1,2,4-triazole-based azo-azomethine dyes were synthesized via condensation of 3,5-diamino-1,2,4-triazole with azo-coupled o-vanillin precursors. The prepared dyes were characterized by IR, UV-vis and 1H NMR spectroscopic methods as well as elemental analyses. Thermal properties of the prepared dyes were examined by thermogravimetric analysis. Results indicated that the framework of the dyes was stable up to 225 °C. Also, the influence of various factors including time and mixed DMSO/EtOH solution on UV-vis spectra of the dyes were investigated.

  6. Infrared spectroscopic characterization of dehydration and accompanying phase transition behaviors in NAT-topology zeolites

    NASA Astrophysics Data System (ADS)

    Wang, Hsiu-Wen; Bish, David L.

    2012-04-01

    Relative humidity ( P_{{{text{H}}_{ 2} {text{O}}}} , partial pressure of water)-dependent dehydration and accompanying phase transitions in NAT-topology zeolites (natrolite, scolecite, and mesolite) were studied under controlled temperature and known P_{{{text{H}}_{ 2} {text{O}}}} conditions by in situ diffuse-reflectance infrared Fourier transform spectroscopy and parallel X-ray powder diffraction. Dehydration was characterized by the disappearance of internal H2O vibrational modes. The loss of H2O molecules caused a sequence of structural transitions in which the host framework transformation path was coupled primarily via the thermal motion of guest Na+/Ca2+ cations and H2O molecules. The observation of different interactions of H2O molecules and Na+/Ca2+ cations with host aluminosilicate frameworks under high- and low- P_{{{text{H}}_{ 2} {text{O}}}} conditions indicated the development of different local strain fields, arising from cation-H2O interactions in NAT-type channels. These strain fields influence the Si-O/Al-O bond strength and tilting angles within and between tetrahedra as the dehydration temperature is approached. The newly observed infrared bands (at 2,139 cm-1 in natrolite, 2,276 cm-1 in scolecite, and 2,176 and 2,259 cm-1 in mesolite) result from strong cation-H2O-Al-Si framework interactions in NAT-type channels, and these bands can be used to evaluate the energetic evolution of Na+/Ca2+ cations before and after phase transitions, especially for scolecite and mesolite. The 2,176 and 2,259 cm-1 absorption bands in mesolite also appear to be related to Na+/Ca2+ order-disorder that occur when mesolite loses its Ow4 H2O molecules.

  7. Infrared spectroscopic characterization of dehydration and accompanying phase transition behaviors in NAT-topology zeolites

    SciTech Connect

    Wang, Hsiu-Wen; Bishop, David

    2012-01-01

    Relative humidity (PH2O, partial pressure of water)-dependent dehydration and accompanying phase transitions in NAT-topology zeolites (natrolite, scolecite, and mesolite) were studied under controlled temperature and known PH2O conditions by in situ diffuse-reflectance infrared Fourier transform spectroscopy and parallel X-ray powder diffraction. Dehydration was characterized by the disappearance of internal H2O vibrational modes. The loss of H2O molecules caused a sequence of structural transitions in which the host framework transformation path was coupled primarily via the thermal motion of guest Na?/Ca2? cations and H2O molecules. The observation of different interactions of H2O molecules and Na?/Ca2? cations with host aluminosilicate frameworks under highand low-PH2O conditions indicated the development of different local strain fields, arising from cation H2O interactions in NAT-type channels. These strain fields influence the Si O/Al O bond strength and tilting angles within and between tetrahedra as the dehydration temperature is approached. The newly observed infrared bands (at 2,139 cm-1 in natrolite, 2,276 cm-1 in scolecite, and 2,176 and 2,259 cm-1 in mesolite) result from strong cation H2O Al Si framework interactions in NAT-type channels, and these bands can be used to evaluate the energetic evolution of Na?/Ca2? cations before and after phase transitions, especially for scolecite and mesolite. The 2,176 and 2,259 cm-1 absorption bands in mesolite also appear to be related to Na?/Ca2? order disorder that occur when mesolite loses its Ow4 H2O molecules.

  8. [The spectroscopic study of topaz].

    PubMed

    Wang, B; Tu, J

    2000-02-01

    In this paper, the natural gem material--Topaz (colorless transparent samples and reactor irradiation induced blue color samples) was studied on the spectroscopic analysis of Fourier transformation infrared spectrum (FTIR) and FT-Raman spectrum. The structure of topaz consists of OH groups and SiO4 groups. Si-O vibration spectrum was characterized with the group theoretical analysis. OH stretching modes of vibration showed many changes among the different color samples, the reason of the changes was explained. The color origin was preliminary investigated by ultra-violet and visible absorption spectrum. PMID:12953446

  9. Anion pairs in room temperature ionic liquids predicted by molecular dynamics simulation, verified by spectroscopic characterization

    SciTech Connect

    Schwenzer, Birgit; Kerisit, Sebastien N.; Vijayakumar, M.

    2014-01-01

    Molecular-level spectroscopic analyses of an aprotic and a protic room-temperature ionic liquid, BMIM OTf and BMIM HSO4, respectively, have been carried out with the aim of verifying molecular dynamics simulations that predict anion pair formation in these fluid structures. Fourier-transform infrared spectroscopy, Raman spectroscopy and nuclear magnetic resonance spectroscopy of various nuclei support the theoretically-determined average molecular arrangements.

  10. Synthesis, spectroscopic characterization and quantum chemical computational studies of (S)-N-benzyl-1-phenyl-5-(pyridin-2-yl)-pent-4-yn-2-amine

    NASA Astrophysics Data System (ADS)

    Kose, Etem; Atac, Ahmet; Karabacak, Mehmet; Karaca, Caglar; Eskici, Mustafa; Karanfil, Abdullah

    2012-11-01

    The synthesis and characterization of a novel compound (S)-N-benzyl-1-phenyl-5-(pyridin-2-yl)-pent-4-yn-2-amine (abbreviated as BPPPYA) was presented in this study. The spectroscopic properties of the compound were investigated by FT-IR, NMR and UV spectroscopy experimentally and theoretically. The molecular geometry and vibrational frequencies of the BPPPYA in the ground state were calculated by using density functional theory (DFT) B3LYP method invoking 6-311++G(d,p) basis set. The geometry of the BPPPYA was fully optimized, vibrational spectra were calculated and fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. The results of the energy and oscillator strength calculated by time-dependent density functional theory (TD-DFT) and CIS approach complement with the experimental findings. Total and partial density of state (TDOS and PDOS) and also overlap population density of state (COOP or OPDOS) diagrams analysis were presented. The theoretical NMR chemical shifts (1H and 13C) complement with experimentally measured ones. The dipole moment, linear polarizability and first hyperpolarizability values were also computed. The linear polarizabilities and first hyper polarizabilities of the studied molecule indicate that the compound is a good candidate of nonlinear optical materials. The calculated vibrational wavenumbers, absorption wavelengths and chemical shifts showed the best agreement with the experimental results.

  11. Electrochemical Kinetics and X-ray Absorption Spectroscopic Investigations of Oxygen Reduction on Chalcogen-Modified Ruthenium Catalysts in Alkaline Media

    SciTech Connect

    N Ramaswamy; R Allen; S Mukerjee; Y

    2011-12-31

    The oxygen reduction reaction (ORR) in alkaline media has been investigated on chalcogen-modified ruthenium nanoparticles (Ru/C, Se/Ru/C, Se/RuMo/C, S/Ru/C, S/RuMo/C) synthesized in-house via aqueous routes. In acidic medium, it is well known that modification by a chalcogen prevents the oxidation of the underlying transition-metal (Ru) surface, thereby promoting direct molecular O{sub 2} adsorption on the Ru metal. On an unmodified Ru catalyst in alkaline media, the surface oxides on Ru mediate the 2e{sup -} reduction of molecular O{sub 2} to a stable peroxide anion (HO{sub 2}{sup -}) intermediate via an outer-sphere electron-transfer mechanism. This increases the activity of HO{sub 2}{sup -} near the electrode surface and decreases the overpotential for ORR by effectively carrying out the reduction of HO{sub 2}{sup -} to OH{sup -} at the oxide-free ruthenium metal site. An increase in ORR activity of Ru is observed by modification with a chalcogen; however, the increase is not as significant as observed in acidic media. Ternary additives, such as Mo, were found to significantly improve the stability of the chalcogen-modified catalysts. Detailed investigations of the ORR activity of this class of catalyst have been carried out in alkaline media along with comparisons to acidic media wherever necessary. A combination of electrochemical and X-ray absorption spectroscopic (EXAFS, XANES, {Delta}{mu}) studies has been performed in order to understand the structure/property relationships of these catalysts within the context of ORR in alkaline electrolytes.

  12. Combined Mssbauer, multi-edge X-ray absorption spectroscopic, and density functional theoretical study of the radical SAM enzyme spore photoproduct lyase

    PubMed Central

    Silver, Sunshine C.; Gardenghi, David J.; Naik, Sunil G.; Shepard, Eric M.; Huynh, Boi Hanh

    2014-01-01

    Spore photoproduct lyase (SPL), a member of the radical SAM superfamily, catalyzes the direct reversal of the spore photoproduct (SP), a thymine dimer specific to bacterial spores, to two thymines. SPL requires S-adenosyl-L-methionine (SAM) and a redox active [4Fe-4S] cluster for catalysis. Mssbauer analysis of anaerobically purified SPL indicates the presence of a mixture of cluster states with the majority (40%) as [2Fe-2S]2+ and a smaller amount (15%) as [4Fe-4S]2+ clusters. Upon reduction, the cluster content changes to primarily (60%) [4Fe-4S]+. The speciation information from Mssbauer data allowed us to deconvolute iron and sulfur K-edge X-ray absorption spectra to uncover electronic (XANES) and geometric (EXAFS) structural features of the Fe-S clusters, and their interactions with SAM. The Fe K-edge EXAFS provide evidence for elongation of a [2Fe-2S] rhomb of the [4Fe-4S] cluster upon binding SAM on the basis of an FeFe scatterer at 3.0 . The XANES spectra of reduced SPL in the absence and presence of SAM overlay, indicating that SAM is not undergoing reductive cleavage. The XAS data for SPL samples and data for model complexes from literature allowed for the deconvolution of contributions from [2Fe-2S] and [4Fe-4S] clusters to the sulfur K-edge XANES spectra. The analysis of pre-edge features revealed electronic changes in the Fe-S clusters as a function of SAM presence. The spectroscopic findings were further corroborated by density functional theory calculations that provided insights into structural and electronic perturbations that can be correlated by considering the role of SAM as a catalyst or substrate. PMID:24532333

  13. Modified polyamines for CO{sub 2} absorption. Product preparation and characterization

    SciTech Connect

    De Filippis, P.; Giavarini, C.; Maggi, C.; Rinaldi, G.; Silla, R.

    2000-05-01

    Aliphatic polyamines easily absorb acidic gases but unfortunately are not suitable for industrial application because their solutions are difficult to regenerate. Molecular modification is of primary importance to reduce their basicity and to allow their use in acid gas recovery processes. Various modified polyamines were prepared by reacting tetraethylenepentamine (TEPA) with formaldehyde and formaldehyde/phenol in various molar ratios. The physical and chemical characterization of the synthesized products showed a general reduction of basicity; the modification of TEPA with formaldehyde and phenol gave products with high CO{sub 2} absorption capacity and easier regeneration; moreover, the heat of reaction during CO{sub 2} absorption was reduced. The selected compound had a TEPA/CH{sub 2}O/C{sub 6}H{sub 5}OH ratio equal to 1/0.5/0.4. This new product showed higher cyclic capacity, higher absorption rate, and lower degradation compared with diethanolamine under the same experimental conditions. The product is stable, constant in composition, and suitable for industrial scale-up.

  14. Ghanaian cocoa bean fermentation characterized by spectroscopic and chromatographic methods and chemometrics.

    PubMed

    Aculey, Patrick C; Snitkjaer, Pia; Owusu, Margaret; Bassompiere, Marc; Takrama, Jemmy; Nørgaard, Lars; Petersen, Mikael A; Nielsen, Dennis S

    2010-08-01

    Export of cocoa beans is of great economic importance in Ghana and several other tropical countries. Raw cocoa has an astringent, unpleasant taste, and flavor, and has to be fermented, dried, and roasted to obtain the characteristic cocoa flavor and taste. In an attempt to obtain a deeper understanding of the changes in the cocoa beans during fermentation and investigate the possibility of future development of objective methods for assessing the degree of fermentation, a novel combination of methods including cut test, colorimetry, fluorescence spectroscopy, NIR spectroscopy, and GC-MS evaluated by chemometric methods was used to examine cocoa beans sampled at different durations of fermentation and samples representing fully fermented and dried beans from all cocoa growing regions of Ghana. Using colorimetry it was found that samples moved towards higher a* and b* values as fermentation progressed. Furthermore, the degree of fermentation could, in general, be well described by the spectroscopic methods used. In addition, it was possible to link analysis of volatile compounds with predictions of fermentation time. Fermented and dried cocoa beans from the Volta and the Western regions clustered separately in the score plots based on colorimetric, fluorescence, NIR, and GC-MS indicating regional differences in the composition of Ghanaian cocoa beans. The study demonstrates the potential of colorimetry and spectroscopic methods as valuable tools for determining the fermentation degree of cocoa beans. Using GC-MS it was possible to demonstrate the formation of several important aroma compounds such 2-phenylethyl acetate, propionic acid, and acetoin and the breakdown of others like diacetyl during fermentation. Practical Application: The present study demonstrates the potential of using colorimetry and spectroscopic methods as objective methods for determining cocoa bean quality along the processing chain. Development of objective methods for determining cocoa bean quality will be of great importance for quality insurance within the fields of cocoa processing and raw material control in chocolate producing companies. PMID:20722952

  15. Characterization of fine resolution field spectrometers using solar Fraunhofer lines and atmospheric absorption features.

    PubMed

    Meroni, Michele; Busetto, Lorenzo; Guanter, Luis; Cogliati, Sergio; Crosta, Giovanni Franco; Migliavacca, Mirco; Panigada, Cinzia; Rossini, Micol; Colombo, Roberto

    2010-05-20

    The accurate spectral characterization of high-resolution spectrometers is required for correctly computing, interpreting, and comparing radiance and reflectance spectra acquired at different times or by different instruments. In this paper, we describe an algorithm for the spectral characterization of field spectrometer data using sharp atmospheric or solar absorption features present in the measured data. The algorithm retrieves systematic shifts in channel position and actual full width at half-maximum (FWHM) of the instrument by comparing data acquired during standard field spectroscopy measurement operations with a reference irradiance spectrum modeled with the MODTRAN4 radiative transfer code. Measurements from four different field spectrometers with spectral resolutions ranging from 0.05 to 3.5nm are processed and the results validated against laboratory calibration. An accurate retrieval of channel position and FWHM has been achieved, with an average error smaller than the instrument spectral sampling interval. PMID:20490248

  16. Characterization of a new modular decay total absorption gamma-ray spectrometer (DTAS) for FAIR

    SciTech Connect

    Montaner Piza, A.; Tain, J. L.; Agramunt, J.; Algora, A.; Guadilla, V.; Marin, E.; Rice, S.; Rubio, B.

    2013-06-10

    Beta-decay studies are one of the main goals of the DEcay SPECtroscopy experiment (DESPEC) to be installed at the future Facility for Antiproton and Ion Research (FAIR). DESPEC aims at the study of nuclear structure of exotic nuclei. A new modular Decay Total Absorption gamma-ray Spectrometer (DTAS) is being built at IFIC and is specially adapted to studies at fragmentation facilities such as the Super Fragment Separator (Super-FRS) at FAIR. The designed spectrometer is composed of 16 identical NaI(Tl) scintillation crystals. This work focuses on the characterization of these independent modules, as an initial step for the characterization of the full spectrometer. Monte Carlo simulations have been performed in order to understand the detector response.

  17. Characterization of a new modular decay total absorption gamma-ray spectrometer (DTAS) for FAIR

    NASA Astrophysics Data System (ADS)

    Piz, A. Montaner; Tan, J. L.; Agramunt, J.; Algora, A.; Guadilla, V.; Marn, E.; Rice, S.; Rubio, B.

    2013-06-01

    Beta-decay studies are one of the main goals of the DEcay SPECtroscopy experiment (DESPEC) to be installed at the future Facility for Antiproton and Ion Research (FAIR). DESPEC aims at the study of nuclear structure of exotic nuclei. A new modular Decay Total Absorption gamma-ray Spectrometer (DTAS) is being built at IFIC and is specially adapted to studies at fragmentation facilities such as the Super Fragment Separator (Super-FRS) at FAIR. The designed spectrometer is composed of 16 identical NaI(Tl) scintillation crystals. This work focuses on the characterization of these independent modules, as an initial step for the characterization of the full spectrometer. Monte Carlo simulations have been performed in order to understand the detector response.

  18. Spectroscopic characterization of micro- and nanoparticle suspensions with size dynamics in plasmas

    NASA Astrophysics Data System (ADS)

    Mitic, S.; Pustylnik, M. Y.; Kova?evi?, E.; Berndt, J.; Boufendi, L.; Morfill, G. E.

    2012-08-01

    Mitic et al (2011 Opt. Lett. 36 3699) proposed a spectroscopic method of the in situ measurement of the size and optical properties of spherical micro- and nanoparticles with monotonically variable size. The method requires three optical channels: one for the illumination of a particle suspension by white light and two for the measurements of the spectra of scattered light. This allows one to determine the optical properties of the particles in a wide spectral range. In this work an extended description of the experimental setup and data analysis technique are given. Performance of the method is illustrated on particle suspensions in plasmas, exhibiting increase and decrease of particle size.

  19. Spectroscopic characterization of genetically modified flax fibres enhanced with poly-3-hydroxybutyric acid

    NASA Astrophysics Data System (ADS)

    Wrbel-Kwiatkowska, Magdalena; Szopa, Jan; Dymi?ska, Lucyna; M?czka, Miros?aw; Hanuza, Jerzy

    2009-02-01

    Genetically modified flax fibres, derived from transgenic flax with expression of three bacterial genes necessary for synthesis of poly-3-hydroxybutyric acid (PHB), have been analysed. These transgenic flaxes, enhanced with different amount of the PHB, have been studied by FT-IR spectroscopy. The integral intensities of the IR bands have been used for estimation of the chemical content of the normal and transgenic flaxes as well as the differences between the natural and genetically modified flax fibres. The spectroscopic data were compared to those obtained from chemical analysis of flax fibres.

  20. Biochemical and spectroscopic characterization of the blue-green photoreceptor in Halobacterium halobium

    SciTech Connect

    Scherrer, P.; McGinnis, K.; Bogomolni, R.A.

    1987-01-01

    Spectroscopic evidence indicates the presence of a second sensory receptor sR-II in Halobacterium halobium, which causes a repellent response to blue-green light. Reactions with hydroxylamine and NaCNBH/sub 3/ and reconstitution of the bleached pigment with retinal show that it is very similar to the other retinylidene pigments bacteriorhodopsin, halorhodopsin, and especially the earlier-discovered phototaxis receptor, sensory rhodopsin, renamed sR-I587. The second sensory receptor, sR-II480, has an absorbance maximum at 480 nm and undergoes a cyclic photoreaction with a half-time of approximately 200 msec. Its predominant photocycle intermediate absorbs maximally near 360 nm. The receptor can be detected spectroscopically in the presence of sR-I587 and quantitated through its transient response to 450-nm excitation. It is selectively bleached by low hydroxylamine concentrations that are insufficient to bleach sR-I587 significantly. Its photochemical and phototactic activities can be restored by addition of retinal. The mobility of the receptor, on NaDodSO4/polyacrylamide gels, was similar or identical to that of sR-I587 and slightly faster than bacteriorhodopsin, yielding an apparent molecular mass of 23-24 kDa.

  1. Cyanide/isocyanide abundances in the interstellar medium - I. Theoretical spectroscopic characterization

    NASA Astrophysics Data System (ADS)

    Senent, M. L.; Dumouchel, F.; Lique, F.

    2012-02-01

    Modelling molecular abundances in the interstellar medium requires accurate molecular data. In this work, structural and spectroscopic properties of a series of metal cyanides/isocyanide species containing Na, Mg, Al and Si are calculated and compared using highly correlated ab initio calculations. The metal substitution effect on molecular properties is discussed. Isomerization pathways and transitions states are detailed. NaCN shows three isomeric structures, one T shaped and two linear forms, whereas the remaining compounds display two linear minimum energy geometries. For the first time, NaCN secondary minima are described. Second-order perturbation theory spectroscopic parameters are determined from an anharmonic RCCSD(T)/aug-cc-pV5Z force field. Very accurate rotational constants are calculated using a complete basis set and taking into account vibrational effects and the structure variation with core electron correlation. For l-SiCN and l-SiNC, spin-orbit parameters are also provided. Present theoretical results are compared with available experimental data attaining a good agreement.

  2. In situ x-ray absorption spectroscopic study of the Li[Ni1/3Co1/3Mn1/3]O2 cathode material

    NASA Astrophysics Data System (ADS)

    Deb, Aniruddha; Bergmann, Uwe; Cramer, Stephen P.; Cairns, Elton J.

    2005-06-01

    The layered LiNi1/3Co1/3Mn1/3O2 system has recently drawn considerable interest for use as a cathode material for rechargeable lithium batteries. In order to investigate the charge-compensation mechanism and structural perturbations occurring in the system during cycling, in situ x-ray absorption spectroscopy (XAS) measurements were performed utilizing a novel electrochemical in situ cell specifically designed for long term x-ray experiments. The cell was cycled at a moderate rate through a typical Li-ion battery operating voltage range (2.9-4.7 V). The electrode contained 2.025 mg of LiNi1/3Co1/3Mn1/3O2 on a 25-μm Al foil and had an area of 0.79cm2. The x-ray absorption spectroscopy (XAS) measurements were performed at the Ni, Co, and the Mn edges at different states of charge (SOC) during cycling, revealing details about the response of the cathode to Li insertion and extraction processes. Changes of bond distance and coordination number of Ni, Co, and Mn absorbers as a function of the state of charge of the material were obtained from the extended x-ray-absorption fine structure (EXAFS) region of the spectra. The x-ray absorption near-edge structure (XANES) region was studied in order to characterize the oxidation states of the 3d transition metals during cycling (Li extraction/insertion). We found that oxidation states of transition metals in LiNi1/3Co1/3Mn1/3O2 are Ni2+, Co3+, and Mn4+, whereas during charging Ni2+ is oxidized to Ni4+ through an intermediate stage of Ni3+,Co3+ is oxidized almost to Co4+ and, utilizing Faraday's calculation and XAS results, the Co was found to be at Co3.92+ at the end of the charge, while Mn was found to be electrochemically inactive and remains as Mn4+. The EXAFS data that were collected continuously during cycling revealed details about the response of the cathode to Li insertion and extraction. These measurements on the LiNi1/3Co1/3Mn1/3O2 cathode confirmed that the material retains its symmetry and good structural short-range order leading to superior cycling.

  3. Spectroscopic characterization of cysteine and methionine using density functional theory method

    NASA Astrophysics Data System (ADS)

    Naganathappa, Mahadevappa; Chaudhari, Ajay

    2015-05-01

    The present study reports theoretical infrared and electronic absorption spectra of neutral cysteine and methionine molecules in gas phase, their ions and in water ice. We also report infrared and electronic absorption spectra of nitrogen-substituted (in place of sulfur atom) cysteine and methionine. The geometrical parameters, dipole moments, rotational and centrifugal distortional constants for these molecules are reported at B3LYP/6-311++g(d,p) level of theory. A large change in vibrational and electronic absorption spectra has been observed upon ionization of cysteine and methionine. Calculated vibrational frequencies are compared with the available experimental frequencies for the neutral cysteine and methionine in gas phase. An influence of water ice on vibrational frequencies of neutral cysteine and methionine is studied using integral equation formalism polarizable continuum model (IEFPCM) at the same level of theory. Time Dependent Density Functional Theory (TDDFT) approach has been adapted to calculate the electronic absorption spectra of these molecules. The intense lines are suggested in order to detect these molecules in space.

  4. Spectroscopic and photochemical characterization of the red-light sensitive photosensory module of Cph2 from Synechocystis PCC 6803.

    PubMed

    Anders, Katrin; von Stetten, David; Mailliet, Jo; Kiontke, Stephan; Sineshchekov, Vitaly A; Hildebrandt, Peter; Hughes, Jon; Essen, Lars-Oliver

    2011-01-01

    Cyanobacterial phytochromes are a diverse family of light receptors controlling various biological functions including phototaxis. In addition to canonical bona fide phytochromes of the well characterized Cph1/plant-like clade, cyanobacteria also harbor phytochromes that absorb green, violet or blue light. The Synechocystis PCC 6803 Cph2 photoreceptor, a phototaxis inhibitor, is unconventional in bearing two distinct chromophore-binding GAF domains. Whereas the C-terminal GAF domain is most likely involved in blue-light perception, the first two domains correspond to a Cph1-like photosensory module lacking the PAS domain. Biochemical and spectroscopic studies show that this region switches between red (P(r) ) and far-red (P(fr) ) absorbing states. Unlike Cph1, the P(fr) state of Cph2 decays rapidly in darkness. Mutations close to the PCB chromophore further destabilize the P(fr) state without drastically affecting the spectroscopic features such as the quantum efficiency of P(r) ?P(fr) conversion, fluorescence, or the Resonance-Raman signature of the chromophore. Overall, the PAS-less photosensory module of Cph2 resembles Cph1 including its mode of isomerisation, but the P(fr) state is unstable. PMID:21091956

  5. Dehydration experiments on natural omphacites: qualitative and quantitative characterization by various spectroscopic methods

    NASA Astrophysics Data System (ADS)

    Koch-Müller, M.; Abs-Wurmbach, I.; Rhede, D.; Kahlenberg, V.; Matsyuk, S.

    2007-11-01

    A series of natural omphacites from a wide range of P, T occurrences were investigated by electron microprobe (EMP), infrared (IR)-, Mössbauer (MS)- and optical spectroscopy in the UV/VIS spectral range (UV/VIS), secondary ion mass spectrometry (SIMS) and single crystal structure refinement by X-ray diffraction (XRD) to study the influence of hydrogen loss on valence state and site occupancies of iron. In accordance with literature data we found Fe2+ at M1 as well as at M2, and in a first approach assigned Fe3+ to M1, as indicated by MS and XRD results. Hydrogen content of three of our omphacite samples were measured by SIMS. In combination with IR spectroscopy we determined an absorption coefficient: ɛ i,tot = 65,000 ± 3,000 lmolH2O -1 cm-2. Using this new ɛ i,tot value, we obtained water concentrations ranging from 60 to 700 ppm H2O (by weight). Hydrogen loss was simulated by stepwise heating the most water rich samples in air up to 800°C. After heat treatment the samples were analyzed again by IR, MS, UV/VIS, and XRD. Depending on the type of the OH defect, the grade of dehydration with increasing temperature is significantly different. In samples relatively poor in Fe3+ (<0.1 Fe3+ pfu), hydrogen associated with vacancies at M2 (OH bands around 3,450 cm-1) starts to leave the structure at about 550°C and is completely gone at 780°C. Hydrogen associated with Al3+ at the tetrahedral site (OH bands around 3,525 cm-1, Koch-Müller et al., Am Mineral, 89:921-931, 2004) remains completely unaffected by heat treatment up to 700°C. But all hydrogen vanished at about 775°C. However, this is different for a more Fe3+-rich sample (0.2 Fe3+ pfu). Its IR spectrum is characterized by a very intense OH band at 3,515 cm-1 plus shoulder at 3,450 cm-1. We assign this intense high-energy band to vibrations of an OH dipole associated with Fe3+ at M1 and a vacancy either at M1 or M2. OH release during heating is positively correlated with decrease in Fe2+ and combined with increase in Fe3+. That dehydration is correlated with oxidation of Fe2+ is indirectly confirmed by annealing of one sample in a gas mixing furnace at 700°C under reducing conditions keeping almost constant OH- content and giving no indication of Fe2+-oxidation. Obtained data indicate that in samples with a relatively high concentration of Fe2+ at M2 and low-water concentrations, i.e., at a ratio of Fe2+ M2/H > 10 dehydration occurs by iron oxidation of Fe2+ exclusively at the M2 site following the reaction: {left[ {{text{Fe}}^{{{text{2 + [ M2]}}}}{text{OH}}^{ - } } right]} = {left[ {{text{Fe}}^{{{text{3 + [ M2]}}}} {text{O}}^{{{text{2}} - }} } right]} + {text{1/2}}{text{H}}_{{text{2}}} \\uparrow . In samples having relatively low concentration of Fe2+ at M2 but high-water concentrations, i.e., ratio of Fe2+ M2/H < 5.0 dehydration occurs through oxidation of Fe2+ at M1.

  6. Effect of steric hindrance on carbon dioxide absorption into new amine solutions: thermodynamic and spectroscopic verification through solubility and NMR analysis.

    PubMed

    Park, Jung-Yeon; Yoon, Sang Jun; Lee, Huen

    2003-04-15

    Acid gas absorption technology is of great importance in these days for the prevention of global warming and the resulting worldwide climate change. More efficient process design and development for the removal of acid gases has become important, together with the development of new absorbents as one of urgent areas of research in addressing global-warming problems. In the present work, aqueous solutions of 2-amino-2-hydroxymethyl-1,3-propanediol (AHPD), a sterically hindered amine, has been examined as a potential CO2 absorbent and compared with the most commonly used absorbent, monoethanolamine (MEA) solution, through equilibrium solubility measurements and 13C NMR spectroscopic analyses. The solubilities of CO2 in aqueous 10 mass % AHPD solutions were higher than those in aqueous 10 mass % MEA solutions above 4 kPa at 298.15 K, but below 4 kPa, the solubility behavior appeared to be the opposite. The solubility difference between these two solutions increased with the CO2 partial pressures above the crossover pressure. Equilibrated CO2-MEA-H2O and CO2-AHPD-H2O solutions at various CO2 partal pressures ranging from 0.01 to 3000 kPa were analyzed by 13C NMR spectroscopy to provide a more microscopic understanding of the reaction mechanisms in the two solutions. In the CO2-amine-H2O solutions, amine reacted with CO2 to form mainly the protonated amine (AMH+), bicarbonate ion (HCO3-), and carbamate anion (AMCO2-), where the quantitative ratio of bicarbonate ion to carbamate anion strongly influenced the CO2 loading in the amine solutions. A profusion of bicarbonate ions, but a very small amount of carbamate anions, was identified in the CO2-AHPD-H2O solution, whereas a considerable amount of carbamate anions was formed in the CO2-MEA-H2O solution. AHPD contains more hydroxyl groups than nonhindered MEA, and hence, the chemical shifts in its 13C NMR spectra were strongly influenced by the solution pH values. In contrast, MEA appeared to be insensitive to pH. The strong interrelations among CO2 solubility, CO2 partial pressure, bulkiness of the amine structure, and pH identified through the present experimental investigations can provide basic guidelines for finding new potential organic absorbents, including specifically designed amine chemicals. PMID:12731852

  7. Spectroscopic characterization and quantitative determination of atorvastatin calcium impurities by novel HPLC method

    NASA Astrophysics Data System (ADS)

    Gupta, Lokesh Kumar

    2012-11-01

    Seven process related impurities were identified by LC-MS in the atorvastatin calcium drug substance. These impurities were identified by LC-MS. The structure of impurities was confirmed by modern spectroscopic techniques like 1H NMR and IR and physicochemical studies conducted by using synthesized authentic reference compounds. The synthesized reference samples of the impurity compounds were used for the quantitative HPLC determination. These impurities were detected by newly developed gradient, reverse phase high performance liquid chromatographic (HPLC) method. The system suitability of HPLC analysis established the validity of the separation. The analytical method was validated according to International Conference of Harmonization (ICH) with respect to specificity, precision, accuracy, linearity, robustness and stability of analytical solutions to demonstrate the power of newly developed HPLC method.

  8. SEM, EDX, infrared and Raman spectroscopic characterization of the silicate mineral yuksporite.

    PubMed

    Frost, Ray L; Lpez, Andrs; Scholz, Ricardo; Theiss, Frederick L; Romano, Antnio Wilson

    2015-02-25

    The mineral yuksporite (K,Ba)NaCa2(Si,Ti)4O11(F,OH)?H2O has been studied using the combination of SEM with EDX and vibrational spectroscopic techniques of Raman and infrared spectroscopy. Scanning electron microscopy shows a single pure phase with cleavage fragment up to 1.0 mm. Chemical analysis gave Si, Al, K, Na and Ti as the as major elements with small amounts of Mn, Ca, Fe and REE. Raman bands are observed at 808, 871, 930, 954, 980 and 1087 cm(-1) and are typical bands for a natural zeolite. Intense Raman bands are observed at 514, 643 and 668 cm(-1). A very sharp band is observed at 3668 cm(-1) and is attributed to the OH stretching vibration of OH units associated with Si and Ti. Raman bands resolved at 3298, 3460, 3562 and 3628 cm(-1) are assigned to water stretching vibrations. PMID:25240833

  9. SEM, EDX, Infrared and Raman spectroscopic characterization of the silicate mineral yuksporite

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; López, Andrés; Scholz, Ricardo; Theiss, Frederick L.; Romano, Antônio Wilson

    2015-02-01

    The mineral yuksporite (K,Ba)NaCa2(Si,Ti)4O11(F,OH)ṡH2O has been studied using the combination of SEM with EDX and vibrational spectroscopic techniques of Raman and infrared spectroscopy. Scanning electron microscopy shows a single pure phase with cleavage fragment up to 1.0 mm. Chemical analysis gave Si, Al, K, Na and Ti as the as major elements with small amounts of Mn, Ca, Fe and REE. Raman bands are observed at 808, 871, 930, 954, 980 and 1087 cm-1 and are typical bands for a natural zeolite. Intense Raman bands are observed at 514, 643 and 668 cm-1. A very sharp band is observed at 3668 cm-1 and is attributed to the OH stretching vibration of OH units associated with Si and Ti. Raman bands resolved at 3298, 3460, 3562 and 3628 cm-1 are assigned to water stretching vibrations.

  10. Ab initio spectroscopic characterization of borane, BH, in its X1?+ electronic state.

    PubMed

    Koput, Jacek

    2015-11-15

    The accurate potential energy and electric dipole moment functions of borane, BH, in its X1?+ electronic state have been determined from ab initio calculations using the multireference averaged coupled-pair functional method in conjunction with the correlation-consistent core-valence basis sets up to septuple-zeta quality. The higher-order electron correlation, scalar relativistic, adiabatic, and nonadiabatic effects were discussed. Vibration-rotation energy levels of the (11)BH, (11)BD, (10)BH, and (10)BD isotopologues were predicted to near "spectroscopic" accuracy. For the main isotopologue (11)BH, the adiabatic dissociation energy D0 and the effective equilibrium internuclear distance r(e) were predicted to be 28,469??10 cm(-1) and 1.23214??0.0001 , respectively. PMID:26444679

  11. 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.

  12. Chemical and spectroscopic characterization of water extractable organic matter during vermicomposting of cattle dung.

    PubMed

    Lv, Baoyi; Xing, Meiyan; Yang, Jian; Qi, Wensheng; Lu, Yongsen

    2013-03-01

    This work illustrated the characteristics and transformation of water extractable organic matter (WEOM) during vermistabilization (Eisenia fetida) of cattle dung by means of chemical and spectroscopic methods. The independent experiment conducted in triplicate was sampled at the 0, 7, 14, 21, 35, 60 and 90days. Results showed that the DOC kept steady around 2.7gkg(-1) after day 60 and the DOC/DON ratio decreased from 19.77 to 5.26 till the end of vermicomposting. On the other hand, vermicomposting decreased the aliphatic, proteinaceous, carbohydrates components and increased the aromaticity and oxygen-containing functional groups in the WEOM. Moreover, fluorescence spectra and fluorescence regional integration (FRI) results indicated that protein-like groups were degraded and fulvic and humic acid-like compounds were evolved during the vermicomposting process. In all, this study suggested the suitability of WEOM for monitoring the organics transformation and assessing the maturity in the vermicomposting. PMID:23416619

  13. Characterization of multilayer GaAs/AlGaAs transistor structures by variable angle spectroscopic ellipsometry

    NASA Technical Reports Server (NTRS)

    Merkel, Kenneth G.; Snyder, Paul G.; Woollam, John A.; Alterovitz, Samuel; Rai, A. K.

    1989-01-01

    Variable angle of incidence spectroscopic ellipsometry (VASE) has been implemented as a means of determining layer thickness, alloy composition, and growth quality of GaAs/AlGaAs samples composed of relatively thick layers as well as superlattices. The structures studied in this work contained GaAs/AlGaAs multilayers with a superlattice 'barrier' and were grown for later formation of modulation-doped field effect transistors (MODFETs). Sample modeling was performed by treating the superlattice as a bulk AlGaAs layer of unknown composition. Extremely good data fits were realized when five layer thicknesses and two alloy ratios were allowed to vary in a regression analysis. Room temperature excitonic effects associated with the e-hh(1), e-lh(1) and e-hh(2) transitions were observed in the VASE data.

  14. Potential approaches to the spectroscopic characterization of high performance polymers exposed to energetic protons and heavy ions

    NASA Technical Reports Server (NTRS)

    Suleman, Naushadalli K.

    1991-01-01

    A potential limitation to human activity on the lunar surface or in deep space is the exposure of the crew to unacceptably high levels of penetrating space radiations. The radiations of most concerns for such missions are high-energy protons emitted during solar flares, and galactic cosmic rays which are high-energy ions ranging from protons to iron. The development of materials for effective shielding from energetic space radiations will clearly require a greater understanding of the underlying mechanisms of radiation-induced damage in bulk materials. This can be accomplished in part by the detailed spectroscopic characterization of bulk materials that were exposed to simulated space radiations. An experimental data base thus created can then be used in conjunction with existing radiation transport codes in the design and fabrication of effective radiation shielding materials. Electron Paramagnetic Resonance Spectroscopy was proven very useful in elucidating radiation effects in polymers (high performance polymers are often an important components of structural composites).

  15. Synthesis and spectroscopic characterization of water-soluble fluorescent ag nanoclusters.

    PubMed

    Zheng, Chengzhi; Wang, Huiping; Liu, Lingzhi; Zhang, Manjun; Liang, Jiangong; Han, Heyou

    2013-01-01

    Water-soluble fluorescent Ag nanoclusters (NCs) were synthesized at room temperature with sodium dodecyl sulfonate (SDS) as a protective agent. The effects of synthetic conditions on the fluorescence properties of Ag NCs were investigated. The results show that the fluorescence intensity of Ag NCs strongly depends on the synthetic conditions, such as the molar ratio of AgNO3 versus SDS and sodium borohydride (NaBH4), the reaction time, and the pH value of the reaction solution. Under the optimum conditions, the as-prepared Ag NCs exist in face-centered-cubic phase with an average size of 2 nm. Fluorescence spectra of Ag NCs show emission peaks at 365 nm for different excitation wavelength. Resonant absorptions are observed at 203 nm and 277 nm in the absorption spectrum, which can be used to establish the electronic levels in the Ag NCs system. PMID:23762779

  16. Characterizing the Interaction between tartrazine and two serum albumins by a hybrid spectroscopic approach.

    PubMed

    Pan, Xingren; Qin, Pengfei; Liu, Rutao; Wang, Jing

    2011-06-22

    Tartrazine is an artificial azo dye commonly used in food products. The present study evaluated the interaction of tartrazine with two serum albumins (SAs), human serum albumin (HSA) and bovine serum albumin (BSA), under physiological conditions by means of fluorescence, three-dimensional fluorescence, UV-vis absorption, and circular dichroism (CD) techniques. The fluorescence data showed that tartrazine could bind to the two SAs to form a complex. The binding process was a spontaneous molecular interaction procedure, in which van der Waals and hydrogen bond interactions played a major role. Additionally, as shown by the UV-vis absorption, three-dimensional fluorescence, and CD results, tartrazine could lead to conformational and some microenvironmental changes of both SAs, which may affect the physiological functions of SAs. The work provides important insight into the mechanism of toxicity of tartrazine in vivo. PMID:21591756

  17. Low-temperature and time-resolved spectroscopic characterization of the LOV2 domain of Avena sativa phototropin

    SciTech Connect

    Gauden, Magdalena; Crosson, Sean; van Stokkum, I.H.; Grondelle, Rienkvan; Moffat, Keith; Kennis, John T.

    2004-12-13

    The phototropins are plant blue-light receptors that base their light-dependent action on the reversible formation of a covalent bond between a flavin mononucleotide (FMN) cofactor and a conserved cysteine residue in light, oxygen or voltage (LOV) domains. The spectroscopic properties of the LOV2 domain of phototropin 1 of Avena sativa (oat) have been investigated by means of low-temperature absorption and fluorescence spectroscopy and by time-resolved fluorescence spectroscopy. The low-temperature absorption spectrum of the LOV2 domain showed a fine structure around 473 nm, indicating heterogeneity in the flavin binding pocket. The fluorescence quantum yield of the flavin cofactor increased from 0.13 to 0.41 upon cooling the sample from room temperature to 77 K. A pronounced phosphorescence emission around 600 nm was observed in the LOV2 domain between 77 and 120 K, allowing for an accurate positioning of the flavin triplet state in the LOV2 domain at 16900 cm{sup -1}. Fluorescence from the cryotrapped covalent adduct state was extremely weak, with a fluorescence spectrum showing a maximum at 440 nm. Time-resolved fluorescence experiments utilizing a synchroscan streak camera revealed a singlet-excited state lifetime of the LOV2 domain of 2.4 ns. FMN dissolved in aqueous solution showed a pH-dependent lifetime ranging between 2.9 ns at pH 2.0 to 4.7 ns at pH 8.0. No spectral shifting of the flavin emission was observed in the LOV2 domain nor in FMN in aqueous solution.

  18. Green preparation and spectroscopic characterization of plasmonic silver nanoparticles using fruits as reducing agents

    PubMed Central

    re Hyllested, Jes; Espina Palanco, Marta; Hagen, Nicolai; Mogensen, Klaus Bo

    2015-01-01

    Summary Chemicals typically available in plants have the capability to reduce silver and gold salts and to create silver and gold nanoparticles. We report the preparation of silver nanoparticles with sizes between 10 and 300 nm from silver nitrate using fruit extract collected from pineapples and oranges as reducing agents. The evolvement of a characteristic surface plasmon extinction spectrum in the range of 420 nm to 480 nm indicates the formation of silver nanoparticles after mixing silver nitrate solution and fruit extract. Shifts in plasmon peaks over time indicate the growth of nanoparticles. Electron microscopy shows that the shapes of the nanoparticles are different depending on the fruit used for preparation. The green preparation process can result in individual nanoparticles with a very poor tendency to form aggregates with narrow gaps even when aggregation is forced by the addition of NaCl. This explains only modest enhancement factors for near-infrared-excited surface enhanced Raman scattering. In addition to the surface plasmon band, UVvisible absorption spectra show features in the UV range which indicates also the presence of small silver clusters, such as Ag4 2+. The increase of the plasmon absorption correlates with the decrease of absorption band in the UV. This confirms the evolution of silver nanoparticles from silver clusters. The presence of various silver clusters on the surface of the green plasmonic silver nanoparticles is also supported by a strong multicolor luminesce signal emitted by the plasmonic particles during 473 nm excitation. PMID:25821667

  19. Green preparation and spectroscopic characterization of plasmonic silver nanoparticles using fruits as reducing agents.

    PubMed

    re Hyllested, Jes; Espina Palanco, Marta; Hagen, Nicolai; Mogensen, Klaus Bo; Kneipp, Katrin

    2015-01-01

    Chemicals typically available in plants have the capability to reduce silver and gold salts and to create silver and gold nanoparticles. We report the preparation of silver nanoparticles with sizes between 10 and 300 nm from silver nitrate using fruit extract collected from pineapples and oranges as reducing agents. The evolvement of a characteristic surface plasmon extinction spectrum in the range of 420 nm to 480 nm indicates the formation of silver nanoparticles after mixing silver nitrate solution and fruit extract. Shifts in plasmon peaks over time indicate the growth of nanoparticles. Electron microscopy shows that the shapes of the nanoparticles are different depending on the fruit used for preparation. The green preparation process can result in individual nanoparticles with a very poor tendency to form aggregates with narrow gaps even when aggregation is forced by the addition of NaCl. This explains only modest enhancement factors for near-infrared-excited surface enhanced Raman scattering. In addition to the surface plasmon band, UV-visible absorption spectra show features in the UV range which indicates also the presence of small silver clusters, such as Ag4 (2+). The increase of the plasmon absorption correlates with the decrease of absorption band in the UV. This confirms the evolution of silver nanoparticles from silver clusters. The presence of various silver clusters on the surface of the "green" plasmonic silver nanoparticles is also supported by a strong multicolor luminesce signal emitted by the plasmonic particles during 473 nm excitation. PMID:25821667

  20. FTIR spectroscopic, thermal and XRD characterization of hydroxyapatite from new natural sources

    NASA Astrophysics Data System (ADS)

    Shaltout, Abdallah A.; Allam, Moussa A.; Moharram, Mohamed A.

    2011-12-01

    The inorganic constituents of 5 different plants (leaves and stalks) were investigated by using Fourier transformer infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermal analysis including thermal gravimetric analysis (TGA), derivative thermogravimetry (DTG) and differential scanning calorimetry (DSC). These plants are Catha edulis (Khat), basil, mint, green tea and trifolium. The absorption bands of carbonate ions CO 32- was exhibited at 1446 cm -1, and the phosphate ions PO 43- was assigned at 1105 and 1035 cm -1. At high temperatures (600, 700 and 600 C) further absorption bands of the phosphate ions PO 43- was assigned at the frequencies 572, 617, 962, 1043 and 1110 cm -1 and the vibrational absorption band of the carbonate ions CO 32- was assigned at 871, 1416 and 1461 cm -1. X-ray diffraction and thermal analysis confirm the obtained results of FITR. Results showed that the main inorganic constituents of C. edulis and basil leaves are hydroxyapatite whereas the hydroxyapatite content in the other plant samples is less than that in case of C. edulis and basil plant leaves.

  1. Spectroscopic characterization and pulsed laser operation of Eu3+:KGd(WO4)2 crystal

    NASA Astrophysics Data System (ADS)

    Loiko, P. A.; Dashkevich, V. I.; Bagaev, S. N.; Orlovich, V. A.; Yasukevich, A. S.; Yumashev, K. V.; Kuleshov, N. V.; Dunina, E. B.; Kornienko, A. A.; Vatnik, S. M.; Pavlyuk, A. A.

    2013-10-01

    Europium-doped monoclinic potassium gadolinium tungstate KGd(WO4)2 crystals are grown by the top-seeded solution growth (TSSG) technique. Their absorption spectra are studied in detail for principal light polarizations, E ? Np, Nm and Ng. It is accompanied by determination of absorption oscillator strengths by means of the theory of f-f transition intensities for systems with anomalously strong configuration interaction. Spectral and temporal characteristics of luminescence associated with 5D0 ? 7FJ transitions are analyzed, and luminescence branching ratios and the radiative lifetime of the 5D0 state are determined. Stimulated-emission cross-section spectra are evaluated for Eu:KGd(WO4)2 crystal. Pulsed Eu:KGd(WO4)2 lasers operating at room temperature at the wavelength of 702.8 nm (5D0 ? 7F4 transition) are studied at Eu concentration of 10/25 at.%. Under laser pumping at 533.6 nm, a maximum output energy of 570 ?J is obtained. The main limitation for laser operation at 5D0 ? 7F2 transition is strong excited-state absorption via the 5D0 ? 5F4 channel.

  2. Characterization of personal RF electromagnetic field exposure and actual absorption for the general public.

    PubMed

    Joseph, W; Vermeeren, G; Verloock, L; Heredia, Mauricio Masache; Martens, Luc

    2008-09-01

    In this paper, personal electromagnetic field exposure of the general public due to 12 different radiofrequency sources is characterized. Twenty-eight different realistic exposure scenarios based upon time, environment, activity, and location have been defined and a relevant number of measurements were performed with a personal exposure meter. Indoor exposure in office environments can be higher than outdoor exposure: 95th percentiles of field values due to WiFi ranged from 0.36 to 0.58 V m(-1), and for DECT values of 0.33 V m(-1) were measured. The downlink signals of GSM and DCS caused the highest outdoor exposures up to 0.52 V m(-1). The highest total field exposure occurred for mobile scenarios (inside a train or bus) from uplink signals of GSM and DCS (e.g., mobile phones) due to changing environmental conditions, handovers, and higher required transmitted signals from mobile phones due to penetration through windows while moving. A method to relate the exposure to the actual whole-body absorption in the human body is proposed. An application is shown where the actual absorption in a human body model due to a GSM downlink signal is determined. Fiftieth, 95th, and 99 th percentiles of the whole-body specific absorption rate (SAR) due to this GSM signal of 0.58 microW kg(-1), 2.08 microW kg(-1), and 5.01 microW kg(-1) are obtained for a 95th percentile of 0.26 V m(-1). A practical usable function is proposed for the relation between the whole-body SAR and the electric fields. The methodology of this paper enables epidemiological studies to make an analysis in combination with both electric field and actual whole-body SAR values and to compare exposure with basic restrictions. PMID:18695413

  3. Detection and characterization of absorption heterogeneities in KH 2PO 4 crystals

    NASA Astrophysics Data System (ADS)

    Pommis, M.; Damiani, D.; Bertussi, B.; Capoulade, J.; Piombini, H.; Natoli, J. Y.; Mathis, H.

    2006-11-01

    The SOCRATE facility is used for the detection of heterogeneous absorption in large and rapidly grown KH2PO4 (KDP) crystals. The different regions are subsequently characterized by spectrophotometry and laser-damage measurement. In accordance with previous results from the literature we found that, by using the SOCRATE damage measurement set-up with a large beam (300 ? 600 ?m2), the absorption level does not play a major role in the damage mechanism at 355 nm. However, by testing the damage resistance of the same KDP component with a focused beam (9 ?m diameter) at 355 nm, we highlight for the first time significantly different damage resistances between highly and weakly absorbing regions from a KDP crystal. Indeed, with a focused beam, we demonstrate that the laser-damage threshold may be lower in some sectors cut in the pyramidal part than in sectors from the prismatic part. This means that the absorbing defects at high concentration are not the predominant damage precursors at 355 nm.

  4. Physicochemical characterization of five glyburide powders: a BCS based approach to predict oral absorption.

    PubMed

    Wei, Hai; Dalton, Chad; Di Maso, Marie; Kanfer, Isadore; Lbenberg, Raimar

    2008-08-01

    The purpose of this study was to investigate the suitability of physicochemical parameters of Active Pharmaceutical Ingredients (APIs) as input functions for the Advanced Compartmental Absorption and Transit Model (ACAT) to predict the oral absorption of drug products. Five different glyburide APIs were characterized using X-ray powder diffraction (XRPD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Raman spectroscopy, particle size and particle size distribution, specific surface area and true density measurements, as well as dissociation constant (pKa), partition coefficient (log P) and distribution coefficient (log D). The computer simulations were performed using GastroPlus. The results of XPRD, DSC and Raman spectroscopy indicated that no significant differences in crystal form were present in the five APIs. However, significant differences in particle size and particle size distribution were observed. A basic in vitro/in vivo relationship between the APIs' particle size and clinically observed plasma time profiles was established. The study demonstrates that in silico methods can assist the formulation scientist to set meaningful API specifications. Computer simulations could shorten the drug development process since appropriate bioawaivers, based on data from simulation studies, may be justified. PMID:18374555

  5. Predicting X-ray absorption spectra of semiconducting polymers for electronic structure and morphology characterization

    NASA Astrophysics Data System (ADS)

    Su, Gregory; Patel, Shrayesh; Pemmaraju, C. Das; Kramer, Edward; Prendergast, David; Chabinyc, Michael

    2015-03-01

    Core-level X-ray absorption spectroscopy (XAS) reveals important information on the electronic structure of materials and plays a key role in morphology characterization. Semiconducting polymers are the active component in many organic electronics. Their electronic properties are critically linked to device performance, and a proper understanding of semiconducting polymer XAS is crucial. Techniques such as resonant X-ray scattering rely on core-level transitions to gain materials contrast and probe orientational order. However, it is difficult to identify these transitions based on experiments alone, and complementary simulations are required. We show that first-principles calculations can capture the essential features of experimental XAS of semiconducting polymers, and provide insight into which molecular model, such as oligomers or periodic boundary conditions, are best suited for XAS calculations. Simulated XAS can reveal contributions from individual atoms and be used to visualize molecular orbitals. This allows for improved characterization of molecular orientation and scattering analysis. These predictions lay the groundwork for understanding how chemical makeup is linked to electronic structure, and to properly utilize experiments to characterize semiconducting polymers.

  6. Absorption in the Cosmic Web: Characterizing the Intergalactic Medium in Cosmological Filaments

    NASA Astrophysics Data System (ADS)

    Tejos, Nicolas

    2014-10-01

    We propose to observe and characterize the IGM associated with cosmological filaments in a statistical manner up to redshift ~0.4. For this purpose, we have used a published cluster catalog (Hao et al. 2010) to identify massive nodes in the cosmic web. We used cluster-pairs separated by < 20 Mpc (transverse) and < 2000 km/s (along the LOS) to identify zones where filaments should reside with high probabilities. We have selected a single QSO whose sightline passess through a total of 9 independent cluster-pairs (8 of which having spectroscopic redshifts) at impact parameters <10 Mpc (7 of which at < 5 Mpc). We propose to observe the QSO with HST/COS using the G130M and G160M gratings to cover the full FUV spectral range at medium resolution (R~20000). We require observations at S/N>10 to ensure a full characterization of HI and OVI lines at column densities N~10^13 cm^-2. This setup will allow us to detect broad and shallow HI and OVI lines (if any) at the redshifts of these filaments, believed to trace portions of the warm-hot intergalactic medium (WHIM). Combining these new observations with those from our pilot study carried out in cycle 20 (ID 12958, PI Tejos), we aim to provide a firm detection of the WHIM in cosmological filaments, at the 95% confidence level. Our findings will test our understanding of galaxy formation and the role of AGN/supernova feedback by comparing them with state-of-the-art hydrodynamical simulations. We will also test the the hypothesis which states that the majority of OVI absorbers at low-z are confined within <300 kpc from galaxies (i.e. circumgalactic medium) thus not related to the WHIM (Prochaska et al. 2011; Tumlinson et al. 2011).

  7. In situ characterization of few-cycle laser pulses in transient absorption spectroscopy.

    PubMed

    Blttermann, Alexander; Ott, Christian; Kaldun, Andreas; Ding, Thomas; Stoo, Veit; Laux, Martin; Rebholz, Marc; Pfeifer, Thomas

    2015-08-01

    Attosecond transient absorption spectroscopy has thus far been lacking the capability to simultaneously characterize the intense laser pulses at work within a time-resolved quantum-dynamics experiment. However, precise knowledge of these pulses is key to extracting quantitative information in strong-field highly nonlinear light-matter interactions. Here, we introduce and experimentally demonstrate an ultrafast metrology tool based on the time-delay-dependent phase shift imprinted on a strong-field-driven resonance. Since we analyze the signature of the laser pulse interacting with the absorbing spectroscopy target, the laser pulse duration and intensity are determined in situ. As we also show, this approach allows for the quantification of time-dependent bound-state dynamics in one and the same experiment. In the future, such experimental data will facilitate more precise tests of strong-field dynamics theories. PMID:26258333

  8. Instrument for x-ray absorption spectroscopy with in situ electrical control characterizations

    SciTech Connect

    Huang, Chun-Chao; Chang, Shu-Jui; Yang, Chao-Yao; Tseng, Yuan-Chieh; Chou, Hsiung

    2013-12-15

    We report a synchrotron-based setup capable of performing x-ray absorption spectroscopy and x-ray magnetic circular dichroism with simultaneous electrical control characterizations. The setup can enable research concerning electrical transport, element- and orbital-selective magnetization with an in situ fashion. It is a unique approach to the real-time change of spin-polarized electronic state of a material/device exhibiting magneto-electric responses. The performance of the setup was tested by probing the spin-polarized states of cobalt and oxygen of Zn{sub 1-x}Co{sub x}O dilute magnetic semiconductor under applied voltages, both at low (?20 K) and room temperatures, and signal variations upon the change of applied voltage were clearly detected.

  9. Characterization of Si (sub X)Ge (sub 1-x)/Si Heterostructures for Device Applications Using Spectroscopic Ellipsometry

    NASA Technical Reports Server (NTRS)

    Sieg, R. M.; Alterovitz, S. A.; Croke, E. T.; Harrell, M. J.; Tanner, M.; Wang, K. L.; Mena, R. A.; Young, P. G.

    1993-01-01

    Spectroscopic ellipsometry (SE) characterization of several complex Si (sub X)Ge (sub 1-x)/Si heterostructures prepared for device fabrication, including structures for heterojunction bipolar transistors (HBT), p-type and n-type heterostructure modulation doped field effect transistors, has been performed. We have shown that SE can simultaneously determine all active layer thicknesses, Si (sub X)Ge (sub 1-x) compositions, and the oxide overlayer thickness, with only a general knowledge of the structure topology needed a priori. The characterization of HBT material included the SE analysis of a Si (sub X)Ge (sub 1-x) layer deeply buried (600 nanometers) under the silicon emitter and cap layers. In the SE analysis of n-type heterostructures, we examined for the first time a silicon layer under tensile strain. We found that an excellent fit can be obtained using optical constants of unstrained silicon to represent the strained silicon conduction layer. We also used SE to measure lateral sample homogeneity, providing quantitative identification of the inhomogeneous layer. Surface overlayers resulting from prior sample processing were also detected and measured quantitatively. These results should allow SE to be used extensively as a non-destructive means of characterizing Si (sub X)Ge (sub 1-x)/Si heterostructures prior to device fabrication and testing.

  10. Comparative in vitro characterization of moxidectin and doramectin percutaneous absorption through bovine skin.

    PubMed

    Sallovitz, J M; Nejamkin, P; Lifschitz, A L; Virkel, G L; Imperiale, F A; Lanusse, C E

    2012-04-01

    Topical formulations have achieved worldwide acceptance in veterinary medicine because their administration is an easy, less labor-intensive and nonstressing form. Any chemical compound that comes in contact with the skin has the potential to be locally and/or systemically absorbed. However, many factors related to the features of animal skin, composition of the topical formulation and to the drug itself can determine marked differences in the percutaneous absorption process. The aim of the current work was to characterize the pattern of in vitro percutaneous absorption for moxidectin (MXD) and doramectin (DRM), two of the most worldwide used topical macrocyclic lactone antiparasitic compounds in cattle. The work included the development of a simple and inexpensive in vitro assay useful to predict in vivo drug percutaneous absorption in cattle. Both drugs were administered as the commercial formulations intended for their topical administration to cattle. The in vitro studies were carried out using modified Franz-type vertical diffusion cells. Cattle skin slices of 500 ?m thickness were prepared using a dermatome to separate the stratum corneum and upper epidermis from dermis and subcutaneous tissue. The receptor medium was sampled up to 72 h postadministration and drug concentrations were measured by HPLC. The parameters used to estimate the comparative in vitro skin permeation showed marked differences between DRM and MXD. A 5.29-fold longer lag time (T(lag)) was observed for DRM. Similarly, the flux (J) (2.93-fold) and the permeation coefficients (K(p) ) (2.95-fold) in cattle skin were significantly higher (P < 0.05) for DRM compared to those obtained for MXD. Additionally, the data obtained from the in vitro permeation studies was correlated with the plasma concentrations of both compounds achieved in vivo in cattle treated with the same topical formulations. Correlation coefficients between percentage of drug permeated in vitro vs. percentage of drug absorbed in vivo (up to 48 h post-treatment) were 0.856-0.887 (MXD) and 0.976-0.990 (DRM). However, the highest in vitro-in vivo correlations for both molecules were observed up to 24 h post-treatment A rapid screening method for testing different topical formulations can be achieved with the simple in vitro cattle skin permeation technique described here, which has been successfully adapted to test the comparative percutaneous absorption of MXD and DRM. PMID:21521238

  11. A COMPLETE SPECTROSCOPIC CHARACTERIZATION OF SO AND ITS ISOTOPOLOGUES UP TO THE TERAHERTZ DOMAIN

    SciTech Connect

    Martin-Drumel, M. A.; Hindle, F.; Mouret, G.; Cuisset, A.; Cernicharo, J.

    2015-02-01

    In order to obtain accurate terahertz center frequencies for SO and its isotopologues, we have studied the absorption spectrum of SO, {sup 34}SO, and {sup 33}SO up to 2.5 THz using continuous-wave terahertz photomixing based on a frequency comb providing an accuracy down to 10 kHz. Sulfur monoxide was produced in a radio frequency discharge of air in a cell containing pure sulfur. Together with the strong absorption signal of the main isotopologue, transitions of {sup 34}SO ({sup 34}S: 4.21%) and {sup 33}SO ({sup 33}S: 0.75%) were observed in natural abundance. The newly observed transitions constitute an extension of the observed rotational quantum numbers of the molecule toward higher N values, allowing an improvement of the molecular parameters for the three species. An isotopically invariant fit has been performed based on pure rotational and ro-vibrational transitions of all SO isotopologues, enabling their accurate line position prediction at higher frequencies. Thanks to this new set of parameters, it is now possible to predict with very high accuracy the frequencies of the ro-vibrational lines. This should enable the research of SO in the mid-IR using ground-based IR telescopes, space-based telescope archives (Infrared Space Observatory, Spitzer), and future space missions such as the James Webb Space Telescope. This set of parameters is particularly well adapted for the detection of SO lines in O-rich evolved stars or in molecular clouds in absorption against bright IR sources.

  12. Molecular structure and spectroscopic characterization of Carbamazepine with experimental techniques and DFT quantum chemical calculations

    NASA Astrophysics Data System (ADS)

    Suhasini, M.; Sailatha, E.; Gunasekaran, S.; Ramkumaar, G. R.

    2015-04-01

    A systematic vibrational spectroscopic assignment and analysis of Carbamazepine has been carried out by using FT-IR, FT-Raman and UV spectral data. The vibrational analysis were aided by electronic structure calculations - ab initio (RHF) and hybrid density functional methods (B3LYP) performed with standard basis set 6-31G(d,p). Molecular equilibrium geometries, electronic energies, natural bond order analysis, harmonic vibrational frequencies and IR intensities have been computed. A detailed interpretation of the vibrational spectra of the molecule has been made on the basis of the calculated Potential Energy Distribution (PED) by VEDA program. UV-visible spectrum of the compound was also recorded and the electronic properties, such as HOMO and LUMO energies and ?max were determined by HF/6-311++G(d,p) Time-Dependent method. The thermodynamic functions of the title molecule were also performed using the RHF and DFT methods. The restricted Hartree-Fock and density functional theory-based nuclear magnetic resonance (NMR) calculation procedure was also performed, and it was used for assigning the 13C and 1H NMR chemical shifts of Carbamazepine.

  13. Characterization of the binding of nevadensin to bovine serum albumin by optical spectroscopic technique

    NASA Astrophysics Data System (ADS)

    Yu, Zhaolian; Li, Daojin; Ji, Baoming; Chen, Jianjun

    2008-10-01

    Binding of nevadensin to bovine serum albumin (BSA) has been studied in detail at 298 and 310 K using spectrophotometric technique. The intrinsic fluorescence of BSA was strongly quenched by the addition of nevadensin and spectroscopic observations are mainly rationalized in terms of a static quenching process at lower concentration of nevadensin ( Cdrug/ CBSA < 1) and a combined quenching process at higher concentration of nevadensin ( Cdrug/ CBSA > 1). The binding parameters for the reaction at a pH above (7.40) or below (3.40) the isoelectric point have been calculated according to the double logarithm regression curve. The thermodynamic parameters ? H0, ? G0, ? S0 at different temperatures and binding mechanism of nevadensin to BSA at pH 7.40 and 3.40 were evaluated. The binding ability of nevadensin to BSA at pH 7.40 was stronger than that at pH 3.40. Steady fluorescence, synchronous fluorescence and circular dichroism (CD) were applied to investigate protein conformation. A value of 2.15 nm for the average distance r between nevadensin (acceptor) and tryptophan residues (Trp) of BSA (donor) was derived from the fluorescence resonance energy transfer. Moreover, influence of pH on the interaction nevadensin with BSA was investigated.

  14. Evaluation of optical parameters and characterization of ultrasonically sprayed MgO films by spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Kurtaran, S.; Akyuz, I.; Atay, F.

    2013-01-01

    MgO is a chemically stable buffer layer and a good candidate with its unique optical and structural characteristics such as low refractive index and good lattice matching for the deposition of technologically important materials. In this work, we have produced MgO films by a low cost ultrasonic spray pyrolysis technique and tried to improve their characteristics by thermal annealing. MgO films have been obtained on glass substrates at 325 ± 5 °C and annealed at two different temperatures as 500 °C and 600 °C for 2 h. Elemental analyses have been made by energy-dispersive X-ray spectroscopy. Thicknesses, refractive indices and extinction coefficient values have been determined by spectroscopic ellipsometry technique using Cauchy-Urbach model. Band gap values of the films have been calculated using the absorbance spectra and optical method. X-ray diffraction patterns have been used to investigate the structural properties and to calculate lattice parameters. Atomic force microscope images have been taken to see the effect of thermal annealing on surface morphology. Electrical resistivity values of the films have been determined using a four-point probe set-up. As a result, annealing temperature has a strong effect on the mentioned properties and a low cost ultrasonic spray pyrolysis technique allows the production of new and alternative MgO buffer layers for technological applications.

  15. Minerals from Macedonia XXIII. Spectroscopic and structural characterization of schorl and beryl cyclosilicates.

    PubMed

    Makreski, Petre; Jovanovski, Gligor

    2009-08-01

    IR and Raman spectroscopy study on two collected cyclosilicate species: schorl (from tourmaline group), Na(Fe,Mg)(3)Al(6)(BO(3))(3)Si(6)O(18)(OH,F)(4) and beryl (Be,Mg,Fe)(3)Al(2)Si(6)O(18) were carried out. Although beryl is nominally anhydrous mineral, vibrational results strongly indicate that H(2)O molecules exist in the structural channels. The number of vibrational bands and their frequencies revealed the presence of H(2)O type II, in which C(2) symmetry axis of the water molecule is parallel to the structural channel (and to the c-axis of beryl). On the other hand, it was found that observed bands in the IR and Raman OH stretching region of the other tourmaline varieties appear as a result of the cation combinations involving dominant presence of Mg and Fe cations in the Y structural sites. The strong indication derived from the vibrational spectroscopic results that the studied mineral represents a schorl variety, coincide very well with the results obtained by powder X-ray diffraction and X-ray microprobe analysis. Both minerals show IR spectral similarities in the region below 1500 cm(-1), whereas the resemblance between the Raman spectra (1500-100 cm(-1)) is less expressed confirming that these spectra are more sensitive to compositional changes and to structural disorder. The identification of both minerals was additionally supported by studying the powder X-ray diffraction diagrams. PMID:18722809

  16. Spectroscopic and Chromatographic Characterization of Wastewater Organic Matter from a Biological Treatment Plant

    PubMed Central

    Park, Min-Hye; Lee, Tae-Hwan; Lee, Bo-Mi; Hur, Jin; Park, Dae-Hee

    2010-01-01

    Spectroscopic and chromatographic changes in dissolved organic matter (DOM) characteristics of influent and treated sewage were investigated for a wastewater treatment plant (WWTP) with a biological advanced process. Refractory DOM (R-DOM) was defined as the dissolved organic carbon concentrations of the samples after 28-day incubation for this study. Specific UV absorbance (SUVA), hydrophobicity, synchronous fluorescence spectra and molecular weight (MW) distributions were selected as DOM characteristics. The percent distribution of R-DOM for the effluent was much higher than that of the influent, indicating that biodegradable DOM was selectively removed during the process. Comparison of the influent versus the effluent sewage revealed that SUVA, fulvic-like fluorescence (FLF), humic-like fluorescence (HLF), the apparent MW values were enhanced during the treatment. This suggests that more aromatic and humic-like compounds were enriched during the biological process. No significant difference in the DOM characteristics was observed between the original effluent (i.e., prior to the incubation) and the influent sewage after the incubation. This result suggests that the major changes in wastewater DOM characteristics occurring during the biological advanced process were similar to those for simple microbial incubation. PMID:22315538

  17. Some polyhydroxy azo azomethine derivatives of salicylaldehyde: Synthesis, characterization, spectroscopic, molecular structure and antimicrobial activity studies

    NASA Astrophysics Data System (ADS)

    Odabaşoğlu, Mustafa; Albayrak, Çiğdem; Özkanca, Reşit; Aykan, Fatma Zehra; Lonecke, Peter

    2007-09-01

    Some new substituted polyhydroxy azo-azomethine compounds were prepared by reaction of tris(hydroxymethyl)aminomethane with ( E)-2-hydroxy-5-(phenyldiazenyl) benzaldehyde and its substituted derivatives. The structures of azo and azo-azomethine compounds were determined by IR, UV-vis, 1H NMR and 13C NMR spectroscopic techniques, and/or X-ray diffraction studies. According to IR spectra, all azo-azomethine compounds adopt keto form in solid state. UV-vis analysis has shown the presence of keto-enol tautomerism in solution for all azo-azomethine compounds, except that for nitro substituted derivative, enol form is dominantly favored in solution. At the same time, above mentioned derivative compounds were studied in vitro for their antimicrobial properties. Among the phenylazosalicylaldehyde series compound tested, 4-phenylazosalicylaldehyde, 4-(3-chlorophenylazo)salicylaldehyde, 4-(2-chlorophenylazo)salicylaldehyde, 4-(4-fluorophenylazo)salicylaldehyde, 4-(3-chlorophenylazo)salicylaldehyde and 4-(4-ethylphenylazo)salicylaldehyde showed a weak antimicrobial activity only against gram positive bacteria. On the contrary, phenylazosalicylaldehyde series compounds were reacted tris(hydroxmethyl)aminomethane, that exhibited a strong antimicrobial activity against gram positive bacteria, yeast and mould. Moreover, while the 2-{[1,3-dihydroxy-2-(hydroxymethyl)propan-2-ylimino]methyl}phenol did not show an inhibition on tested microorganism, the addition of phenyldiazine groups to 2-{[1,3-dihydroxy-2-(hydroxymethyl)propan-2-ylimino]methyl}phenol resulted in a strong increases in antimicrobial activity.

  18. Structural, spectroscopic, and electrochemical characterization of boron-doped diamond films from different provenances

    SciTech Connect

    Li, L.F.; Totir, D.A.; Vinokur, N.; Miller, B.; Chottiner, G.; Evans, E.A.; Angus, J.C.; Scherson, D.A.

    1998-05-01

    Morphological, spectroscopic, and electrochemical aspects of boron-doped diamond (BDD) films grown on silicon surfaces originating from three different laboratories have been examined by atomic force microscopy (AF), Raman scattering, Auger electron spectroscopy, and cyclic voltammetry in polyethylene oxide LiClO{sub 4} electrolytes in ultrahigh vacuum. All specimens displayed AFM images characteristic of diamond and Raman spectra consistent with a wide range of boron concentrations (10{sup 19} to 10{sup 21} B atom/cm{sup 3}), with no evidence for the presence of gross graphitic impurities. The cyclic voltammetry of two of the specimens (denoted as GV2 and CWRU), however, showed features at potentials positive to lithium bulk deposition attributed to lithium-ion intercalation/deintercalation phenomena in non-diamond carbon present as a surface impurity, perhaps at the grain boundaries. This finding is consistent with earlier results for a specimen of type GV2 in aqueous electrolytes for which rates of heterogeneous electron transfer for certain redox couples were found higher than those for nominally clean BDD surfaces.

  19. Compound semiconductor detectors for X-ray astronomy: Spectroscopic measurements and material characterization

    SciTech Connect

    Bavdaz, M.; Kraft, S.; Peacock, A.

    1998-12-31

    The use of some specific compound semiconductors in the fabrication of high energy X-ray detectors shows significant potential for X-ray astrophysics space missions. The authors are currently investigating three high purity crystals--CdZnTe, GaAs and TlBr--as the basis for future hard X-ray detectors (above 10 keV). In this paper the authors present the first results on CdZnTe and GaAs based detectors and evaluate the factors currently still constraining the performance. Energy resolutions (FWHM) of 0.9 keV and 1.1 keV at 14 keV and 60 keV, respectively, have been obtained with an epitaxial GaAs detector, while 0.7 keV and 1.5 keV FWHM were measured at the same energies with a CdZnTe detector. Based on these results it is clear, that the next generation of X-ray astrophysics missions now in the planning phase may well consider extending the photon energy range up to {approximately} 100 keV by use of efficient detectors with reasonable spectroscopic capabilities.

  20. Applied quantum chemistry: Spectroscopic detection and characterization of the F{sub 2}BS and Cl{sub 2}BS free radicals in the gas phase

    SciTech Connect

    Jin, Bing; Clouthier, Dennis J.; Sheridan, Phillip M.

    2015-03-28

    In this and previous work [D. J. Clouthier, J. Chem. Phys. 141, 244309 (2014)], the spectroscopic signatures of the X{sub 2}BY (X = H, halogen, Y = O, S) free radicals have been predicted using high level ab initio theory. The theoretical results have been used to calculate the electronic absorption and single vibronic level (SVL) emission spectra of the radicals under typical jet-cooled conditions. Using these diagnostic predictions, the previously unknown F{sub 2}BS and Cl{sub 2}BS free radicals have been identified and characterized. The radicals were prepared in a free jet expansion by subjecting precursor mixtures of BF{sub 3} or BCl{sub 3} and CS{sub 2} vapor to an electric discharge at the exit of a pulsed molecular beam valve. The B{sup ~2}A{sub 1}X{sup ~} {sup 2}B{sub 2} laser-induced fluorescence spectra were found within 150 cm{sup ?1} of their theoretically predicted positions with vibronic structure consistent with our Franck-Condon simulations. The B{sup ~2}A{sub 1} state emits down to the ground state and to the low-lying A{sup ~2}B{sub 1} excited state and the correspondence between the observed and theoretically derived SVL emission Franck-Condon profiles was used to positively identify the radicals and make assignments. Excited state Coriolis coupling effects complicate the emission spectra of both radicals. In addition, a forbidden component of the electronically allowed B{sup ~}X{sup ~} band system of Cl{sub 2}BS is evident, as signaled by the activity in the b{sub 2} modes in the spectrum. Symmetry arguments indicate that this component gains intensity due to a vibronic interaction of the B{sup ~2}A{sub 1} state with a nearby electronic state of {sup 2}B{sub 2} symmetry.

  1. Characterization of protein immobilization at silver surfaces bynear edge x-ray absorption fine structure spectroscopy

    SciTech Connect

    Liu, X.; Jang, C.-H.; Zheng, F.; J rgensen, A.; Denlinger, J.D.; Dickson, K.A.; Raines, R.T.; Abbott, N.L.; Himpsel, F.J.

    2006-06-21

    Ribonuclease A (RNase A) is immobilized on silver surfacesin oriented and random form via self-assembled monolayers (SAMs) ofalkanethiols. The immobilization process is characterized step-by-stepusing chemically selective near-edge X-ray absorption fine structurespectroscopy (NEXAFS) at the C, N, and S K-edges. Causes of imperfectimmobilization are pinpointed, such as oxidation and partial desorptionof the alkanethiol SAMs and incomplete coverage. The orientation of theprotein layer manifests itself in an 18 percent polarization dependenceof the NEXAFS signal from the N 1s to pi* transition of the peptide bond,which is not seen for a random orientation. The S 1s to C-S sigma*transition exhibits an even larger polarization dependence of 41 percent,which is reduced to 5 percent for a random orientation. A quantitativemodel is developed that explains the sign and magnitude of thepolarization dependence at both edges. The results demonstrate thatNEXAFS is able to characterize surface reactions during theimmobilization of proteins and to provide insight into their orientationson surfaces.

  2. Characterizing Protein Complexes with UV absorption, Light Scattering, and Refractive Index Detection.

    NASA Astrophysics Data System (ADS)

    Trainoff, Steven

    2009-03-01

    Many modern pharmaceuticals and naturally occurring biomolecules consist of complexes of proteins and polyethylene glycol or carbohydrates. In the case of vaccine development, these complexes are often used to induce or amplify immune responses. For protein therapeutics they are used to modify solubility and function, or to control the rate of degradation and elimination of a drug from the body. Characterizing the stoichiometry of these complexes is an important industrial problem that presents a formidable challenge to analytical instrument designers. Traditional analytical methods, such as using florescent tagging, chemical assays, and mass spectrometry perturb the system so dramatically that the complexes are often destroyed or uncontrollably modified by the measurement. A solution to this problem consists of fractionating the samples and then measuring the fractions using sequential non-invasive detectors that are sensitive to different components of the complex. We present results using UV absorption, which is primarily sensitive to the protein fraction, Light Scattering, which measures the total weight average molar mass, and Refractive Index detection, which measures the net concentration. We also present a solution of the problem inter-detector band-broadening problem that has heretofore made this approach impractical. Presented will be instrumentation and an analysis method that overcome these obstacles and make this technique a reliable and robust way of non-invasively characterizing these industrially important compounds.

  3. Biochemical and spectroscopic characterization of a novel metalloprotease, cotinifolin from an antiviral plant shrub: Euphorbia cotinifolia.

    PubMed

    Kumar, Reetesh; Singh, Kunwar Awaneesh; Tomar, Ritu; Jagannadham, Medicherla V

    2011-07-01

    A high molecular mass novel metalloprotease, cotinifolin is purified from the latex of Euphorbia cotinifolia by a combination of anion exchange and hydrophobic interaction chromatography. The nonglycosylated enzyme has a molecular mass of 79.76 kDa (ESI-MS) and the isoelectric point of the enzyme is pH 7.7. Cotinifolin hydrolyzes denatured natural substrates such as casein, azoalbumin, and hemoglobin with high specific activity. The K(m) value of the enzyme was found to be 20 ?M with azocasein. The enzyme is not prone to autolysis even at very low concentrations. Polyclonal antibodies specific to enzyme was raised and immunodiffusion reveals that the enzyme has unique antigenic determinants. Maximum caseinolytic activity of cotinifolin is observed in the range of pH 7.0-8.0 and temperature of 50 C. Using 0.2 mL of 1 mM solution of each metal ion, the purified protease was inhibited slightly by Ba? and Mn?, moderately by Mg?, Ca? and Cs? and significantly by Zn?, Cu? and Co?. On the other hand, substantial activation in caseinolytic activity was achieved by Ni?. The enzyme activity was also inhibited by EDTA and o-phenanthroline but not by any other protease inhibitors. Perturbation studies by temperature, pH, and chaotrophs of the enzyme also reveal its high stability as seen by CD, fluorescence and proteolytic activity. Spectroscopic studies reveal that cotinifolin has secondary structural features with ?/? type with approximately 9% of ?-helicity. Easy availability and simple purification procedure makes the enzyme a good system for biophysical study, biotechnological and industrial applications. PMID:21531144

  4. Theoretical spectroscopic characterization at low temperatures of S-methyl thioformate and O-methyl thioformate.

    PubMed

    Senent, M L; Puzzarini, C; Hochlaf, M; Domnguez-Gmez, R; Carvajal, M

    2014-09-14

    Highly correlated ab initio methods are employed to determine spectroscopic properties at low temperatures of two S-analogs of methyl formate: S-methyl thioformate CH3-S-CHO (MSCHO) and O-methyl thioformate CH3-O-CHS (MOCHS). Both species are detectable and they are expected to play an important role in Astrochemistry. Molecular properties are compared with those of the O-analog, methyl formate. Both isomers present two conformers cis and trans. cis-CH3-S-CHO represents the most stable structure lying 4372.2 cm(-1) below cis-CH3-O-CHS. The energy difference between the cis and trans forms is drastically lower for MSCHO (1134 cm(-1)) than for MOCHS (1963.6 cm(-1)). Harmonic and anharmonic fundamentals and the corresponding intensities, as well as the rotational constants for the ground vibrational and first excited torsional states and the centrifugal distortions constants, are provided. Low torsional energy levels have been obtained by solving variationally a two dimensional Hamiltonian expressed in terms of the two torsional degrees of freedom. The corresponding 2D potential energy surfaces have been computed at the CCSD(T)/aug-cc-pVTZ level of theory. The methyl torsional barriers V3(cis) are determined to be 139.7 cm(-1) (CH3-S-CHO) and 670.4 cm(-1) (CH3-O-CHS). The A/E splitting of ground torsional state has been estimated to be 0.438 cm(-1) for CH3-S-CHO and negligible for CH3-O-CHS. PMID:25217912

  5. Theoretical Spectroscopic Characterization at Low Temperatures of Dimethyl Sulfoxide: The Role of Anharmonicity.

    PubMed

    Senent, M L; Dalbouha, S; Cuisset, A; Sadovskii, D

    2015-09-17

    The structural and spectroscopic parameters of dimethyl sulfoxide (DMSO) are predicted from CCSD(T)-F12 calculations that can help to resolve the outstanding problem of the rovibrational spectroscopy. DMSO is a near oblate top that presents a trigonal pyramidal geometry. Rotational parameters are determined at the equilibrium and in selected vibrational states. For the ground state, the rotational constants were calculated to be A0 = 7031.7237 MHz, B0 = 6920.1221 MHz, and C0 = 4223.3389 MHz, at few megahertz from the previous experimental measurements. Ab initio calculations allow us to assert that DMSO rotational constants are strongly dependent on anharmonic effects. Asymmetry increases with the vibrational energy. Harmonic frequencies, torsional parameters, and a two-dimensional potential energy surface (2D-PES) focused to describe the internal rotation of the two methyl groups are determined at the CCSD(T)-F12 level of theory. For the medium and small amplitude motions, anharmonic effects are estimated with MP2 theory getting an excellent agreement with experimental data for the ν11 and ν23 fundamentals. Torsional energies and transitions are computed variationally form the 2D-PES that denotes strong interactions between both internal tops. The vibrationally corrected V3 torsional barrier is evaluated to be 965.32 cm(-1). The torsional splitting of the ground vibrational state has been estimated to be lower than 0.01 cm(-1). Although the ν13 torsional fundamental is found at 229.837 cm(-1) in good agreement with previous assessment, there is not accord for the low intense transition ν24. A new assignment predicting ν24 to lie between 190 and 195 cm(-1) is proposed. PMID:26317485

  6. Theoretical spectroscopic characterization at low temperatures of S-methyl thioformate and O-methyl thioformate

    NASA Astrophysics Data System (ADS)

    Senent, M. L.; Puzzarini, C.; Hochlaf, M.; Domnguez-Gmez, R.; Carvajal, M.

    2014-09-01

    Highly correlated ab initio methods are employed to determine spectroscopic properties at low temperatures of two S-analogs of methyl formate: S-methyl thioformate CH3-S-CHO (MSCHO) and O-methyl thioformate CH3-O-CHS (MOCHS). Both species are detectable and they are expected to play an important role in Astrochemistry. Molecular properties are compared with those of the O-analog, methyl formate. Both isomers present two conformers cis and trans. cis-CH3-S-CHO represents the most stable structure lying 4372.2 cm-1 below cis-CH3-O-CHS. The energy difference between the cis and trans forms is drastically lower for MSCHO (1134 cm-1) than for MOCHS (1963.6 cm-1). Harmonic and anharmonic fundamentals and the corresponding intensities, as well as the rotational constants for the ground vibrational and first excited torsional states and the centrifugal distortions constants, are provided. Low torsional energy levels have been obtained by solving variationally a two dimensional Hamiltonian expressed in terms of the two torsional degrees of freedom. The corresponding 2D potential energy surfaces have been computed at the CCSD(T)/aug-cc-pVTZ level of theory. The methyl torsional barriers V3(cis) are determined to be 139.7 cm-1 (CH3-S-CHO) and 670.4 cm-1 (CH3-O-CHS). The A/E splitting of ground torsional state has been estimated to be 0.438 cm-1 for CH3-S-CHO and negligible for CH3-O-CHS.

  7. Spectroscopic investigation and optical characterization of Eu3+ ions in K-Nb-Si glasses.

    PubMed

    Murali Mohan, M; Rama Moorthy, L; Ramachari, D; Jayasankar, C K

    2014-01-24

    This paper reports on the effect of concentration of Eu(3+) ions in K2O-Nb2O5-SiO2-Eu2O3 (KNbSiEu) glasses prepared by the melt quenching technique. By using the Judd-Ofelt (JO) theory, the intensity parameters ?? (?=2, 4, 6) have been determined from the absorption and emission spectra of Eu(3+) ions under different constraints. The radiative properties of some of the excited states of Eu(3+) ions have been calculated. The decay curves of (5)D0 level exhibited single exponential for all the Eu(3+) ions concentrations. From these results, it is suggested that the strong red emission at 616 nm corresponding to the (5)D0?(7)F2 transition could be used for the development of optical display devices. PMID:24161859

  8. Characterization of the Interaction between Eupatorin and Bovine Serum Albumin by Spectroscopic and Molecular Modeling Methods

    PubMed Central

    Xu, Hongliang; Yao, Nannan; Xu, Haoran; Wang, Tianshi; Li, Guiying; Li, Zhengqiang

    2013-01-01

    This study investigated the interaction between eupatorin and bovine serum albumin (BSA) using ultraviolet-visible (UV-vis) absorption, fluorescence, synchronous fluorescence, circular dichroism (CD) spectroscopies, and molecular modeling at pH 7.4. Results of UV-vis and fluorescence spectroscopies illustrated that BSA fluorescence was quenched by eupatorin via a static quenching mechanism. Thermodynamic parameters revealed that hydrophobic and electrostatic interactions played major roles in the interaction. Moreover, the efficiency of energy transfer, and the distance between BSA and acceptor eupatorin, were calculated. The effects of eupatorin on the BSA conformation were analyzed using UV-vis, CD, and synchronous fluorescence. Finally, the binding of eupatorin to BSA was modeled using the molecular docking method. PMID:23839090

  9. Design and spectroscopic characterization of novel series of near infrared indocyanine dyes

    NASA Astrophysics Data System (ADS)

    Abd-El-Aziz, Alaa S.; Strohm, Elizabeth A.; Okasha, Rawda M.

    2015-07-01

    A novel series of near infrared heptamethine indocyanine dyes bearing various aromatic chromophores has been synthesized. The synthetic methodology was achieved via ester condensation reactions of heptamethine indocyanine parent dye with carboxylic moiety and aromatic compounds such as anthracene, pyrene and thiophene derivatives. Structural analysis of the newly prepared dyes was accomplished using one- and two-dimensional nuclear magnetic resonance, infrared spectroscopy and electrospray ionization mass spectrometry. These dyes exhibited high molar absorptivity based on the UV-visible/near-infrared spectral data. Fluorescence emission spectral data was used to determine the relative quantum yield. The new dyes displayed formation of H-aggregates in water at low concentrations, while this behavior was not observed in methanol.

  10. Synthesis, spectroscopic, structural and thermal characterizations of vanadyl(IV) adenine complex prospective as antidiabetic drug agent

    NASA Astrophysics Data System (ADS)

    El-Megharbel, Samy M.; Hamza, Reham Z.; Refat, Moamen S.

    2015-01-01

    The vanadyl(IV) adenine complex; [VO(Adn)2]ṡSO4; was synthesized and characterized. The molar conductivity of this complex was measured in DMSO solution that showed an electrolyte nature. Spectroscopic investigation of the green solid complex studied here indicate that the adenine acts as a bidentate ligand, coordinated to vanadyl(IV) ions through the nitrogen atoms N7 and nitrogen atom of amino group. Thus, from the results presented the vanadyl(IV) complex has square pyramid geometry. Further characterizations using thermal analyses and scanning electron techniques was useful. The aim of this paper was to introduce a new drug model for the diabetic complications by synthesized a novel mononuclear vanadyl(IV) adenine complex to mimic insulin action and reducing blood sugar level. The antidiabetic ability of this complex was investigated in STZ-induced diabetic mice. The results suggested that VO(IV)/adenine complex has antidiabetic activity, it improved the lipid profile, it improved liver and kidney functions, also it ameliorated insulin hormone and blood glucose levels. The vanadyl(IV) complex possesses an antioxidant activity and this was clear through studying SOD, CAT, MDA, GSH and methionine synthase. The current results support the therapeutic potentiality of vanadyl(IV)/adenine complex for the management and treatment of diabetes.

  11. Synthesis, spectroscopic, structural and thermal characterizations of vanadyl(IV) adenine complex prospective as antidiabetic drug agent.

    PubMed

    El-Megharbel, Samy M; Hamza, Reham Z; Refat, Moamen S

    2015-01-25

    The vanadyl(IV) adenine complex; [VO(Adn)2]?SO4; was synthesized and characterized. The molar conductivity of this complex was measured in DMSO solution that showed an electrolyte nature. Spectroscopic investigation of the green solid complex studied here indicate that the adenine acts as a bidentate ligand, coordinated to vanadyl(IV) ions through the nitrogen atoms N7 and nitrogen atom of amino group. Thus, from the results presented the vanadyl(IV) complex has square pyramid geometry. Further characterizations using thermal analyses and scanning electron techniques was useful. The aim of this paper was to introduce a new drug model for the diabetic complications by synthesized a novel mononuclear vanadyl(IV) adenine complex to mimic insulin action and reducing blood sugar level. The antidiabetic ability of this complex was investigated in STZ-induced diabetic mice. The results suggested that VO(IV)/adenine complex has antidiabetic activity, it improved the lipid profile, it improved liver and kidney functions, also it ameliorated insulin hormone and blood glucose levels. The vanadyl(IV) complex possesses an antioxidant activity and this was clear through studying SOD, CAT, MDA, GSH and methionine synthase. The current results support the therapeutic potentiality of vanadyl(IV)/adenine complex for the management and treatment of diabetes. PMID:25150436

  12. Synthesis and Spectroscopic Characterization of Some New Axially Ligated Indium(III) Macrocyclic Complexes and Their Biological Activities

    PubMed Central

    Bajju, Gauri D.; Gupta, Deepmala; Kapahi, Ashu

    2014-01-01

    The synthesis and spectroscopic characterization of new axially ligated indium(III) porphyrin complexes were reported. Chloroindium(III) porphyrin (TPPIn-Cl) was obtained in good yield by treating the corresponding free base with indium trichloride. The action of the different phenols on chloroderivatives (TPPIn-Cl) led to the corresponding phenolato complexes (TPPIn-X). These derivatives were characterized on the basis of mass spectrometry, 1H-NMR, IR, and UV-visible data. The separation and isolation of these derivatives have been achieved through chromatography. The spectral properties of free base porphyrin and its corresponding metallated and axially ligated indium(III) porphyrin compounds were compared with each other. A detailed analysis of UV-Vis, 1H-NMR, and IR suggested the transformation from free base porphyrin to indium(III) porphyrin. Besides, 13C-NMR and fluorescence spectra were also reported and interpreted. The stability of these derivatives has also been studied through thermogravimetry. The complexes were also screened for anticancerous activities. Among all the complexes, 4-MePhO-InTPP shows highest anticancerous activity. The title complexe, TPPIn-X (where X = different phenolates), represents a five-coordinate indium(III) porphyrin complex in a square-pyramidal geometry with the phenolate anion as the axial ligand. PMID:25140121

  13. Hafnium(IV) chloride complexes with chelating β-ketiminate ligands: Synthesis, spectroscopic characterization and volatility study

    NASA Astrophysics Data System (ADS)

    Patil, Siddappa A.; Medina, Phillip A.; Antic, Aleks; Ziller, Joseph W.; Vohs, Jason K.; Fahlman, Bradley D.

    2015-09-01

    The synthesis and characterization of four new β-ketiminate hafnium(IV) chloride complexes dichloro-bis[4-(phenylamido)pent-3-en-2-one]-hafnium (4a), dichloro-bis[4-(4-methylphenylamido)pent-3-en-2-one]-hafnium (4b), dichloro-bis[4-(4-methoxyphenylamido)pent-3-en-2-one]-hafnium (4c), and dichloro-bis[4-(4-chlorophenylamido)pent-3-en-2-one]-hafnium (4d) are reported. All the complexes (4a-d) were characterized by spectroscopic methods (1H NMR, 13C NMR, IR), and elemental analysis while the compound 4c was further examined by single-crystal X-ray diffraction, revealing that the complex is monomer with the hafnium center in octahedral coordination environment and oxygens of the chelating N-O ligands are trans to each other and the chloride ligands are in a cis arrangement. Volatile trends are established for four new β-ketiminate hafnium(IV) chloride complexes (4a-d). Sublimation enthalpies (ΔHsub) were calculated from thermogravimetric analysis (TGA) data, which show that, the dependence of ΔHsub on the molecular weight (4a-c) and inductive effects from chlorine (4d).

  14. Spectroscopic and Electrical Characterization of FeSO4.7H2O Doped Poly (o-toluidine)

    NASA Astrophysics Data System (ADS)

    Kumar, Anand; Ali, Vazid; Kumar, Sushil; Husain, M.

    2011-12-01

    Poly (o-toluidine) has received much attention because of its electronic, thermoelectric, environmental stability and diversified utilization. Various dopants and solvents for control of physical and chemical properties of poly (o-toluidine) has been examined. In the present work, poly (o-toluidine) has been synthesized by chemical oxidative polymerization in acidic medium using o-toluidine monomer. The Poly (o-toluidine) so obtained has been doped with transition metal salt FeSO4.7H2O with different concentration such as 2, 6 and 10% (w/w). In order to investigate the influence of dopant on the properties of poly (o-toluidine), the prepared samples have been characterized by UV-visible spectroscopy, FTIR and I-V characterization. Samples for UV-visible spectroscopy were prepared by dissolving a small amount of doped poly (o-toluidine) in tetrahydrofuran in quartz cuvvets. The absorption spectra of the samples were recorded in wavelength range 200-800 nm using UV-visible spectrophotometer. UV-visible study revealed that optical parameters such as absorption coefficient and band gap changed considerably with concentration. Samples for FTIR spectroscopy were prepared as pellets by pressing a mixture of doped poly (o-toluidine) and potassium bromide. FTIR spectra were recorded in wavenumber range 400-4000 cm-1 on FTIR spectrophotometer. It has been observed that dc conductivity of the samples, measured at room temperature (300 K), increases with increase in doping concentration.

  15. Americium characterization by X-ray fluorescence and absorption spectroscopy in plutonium uranium mixed oxide

    SciTech Connect

    Degueldre, Claude Cozzo, Cedric; Martin, Matthias; Grolimund, Daniel; Mieszczynski, Cyprian

    2013-06-01

    Plutonium uranium mixed oxide (MOX) fuels are currently used in nuclear reactors. The actinides in these fuels need to be analyzed after irradiation for assessing their behaviour with regard to their environment and the coolant. In this work the study of the atomic structure and next-neighbour environment of Am in the (Pu,U)O? lattice in an irradiated (60 MW d kg?) MOX sample was performed employing micro-X-ray fluorescence (-XRF) and micro-X-ray absorption fine structure (-XAFS) spectroscopy. The chemical bonds, valences and stoichiometry of Am (~0.66 wt%) are determined from the experimental data gained for the irradiated fuel material examined in its peripheral zone (rim) of the fuel. In the irradiated sample Am builds up as Am? species within an [AmO?]? coordination environment (e.g. >90%) and no (<10%) Am(IV) or (V) can be detected in the rim zone. The occurrence of americium dioxide is avoided by the redox buffering activity of the uranium dioxide matrix. - Graphical abstract: Americium LIII XAFS spectra recorded for the irradiated MOX sub-sample in the rim zone for a 300 ?m300 ?m beam size area investigated over six scans of 4 h. The records remain constant during multi-scan. The analysis of the XAFS signal shows that Am is found as trivalent in the UO? matrix. This analytical work shall open the door of very challenging analysis (speciation of fission product and actinides) in irradiated nuclear fuels. - Highlights: Americium was characterized by microX-ray absorption spectroscopy in irradiated MOX fuel. The americium redox state as determined from XAS data of irradiated fuel material was Am(III). In the sample, the Am? face an AmO??coordination environment in the (Pu,U)O? matrix. The americium dioxide is reduced by the uranium dioxide matrix.

  16. Spectroscopic characterization of the chemical composition of the potent sweetener Vartamil

    NASA Astrophysics Data System (ADS)

    Kolosova, T. E.; Prokhodchenko, L. K.; Pilipenko, V. V.; Suboch, V. P.

    2008-03-01

    The chemical composition of the potent sweetener Vartamil was characterized using spectral methods. It was demonstrated that Vartamil is a mixture of saccharose chloro derivatives, the main one of which is 4,1',6'-trichloro-4,1',6'-trideoxygalactosaccharose (Sucralose).

  17. Arsenate Uptake by Calcite: Macroscopic and Spectroscopic Characterization of Adsorption and Incorporation Mechanisms

    SciTech Connect

    Alexandratos,V.; Elzinga, E.; Reeder, R.

    2007-01-01

    Batch uptake experiments and X-ray element mapping and spectroscopic techniques were used to investigate As(V) (arsenate) uptake mechanisms by calcite, including adsorption and coprecipitation. Batch sorption experiments in calcite-equilibrated suspensions (pH 8.3; PCO{sub 2} = 10{sup -3.5} atm) reveal rapid initial sorption to calcite, with sorption rate gradually decreasing with time as available sorption sites decrease. An As(V)-calcite sorption isotherm determined after 24 h equilibration exhibits Langmuir-like behavior up to As concentrations of 300 {mu}M. Maximum distribution coefficient values (K{sub d}), derived from a best fit to a Langmuir model, are {approx}190 L kg{sup -1}. Calcite single crystals grown in the presence of As(V) show well-developed rhombohedral morphology with characteristic growth hillocks on (10{bar 1}4) surfaces at low As(V) concentrations ({<=}5 {mu}M), but habit modification is evident at As(V) concentrations {>=}30 {mu}M in the form of macrostep development preferentially on the - vicinal surfaces of growth hillocks. Micro-X-ray fluorescence element mapping of (10{bar 1}4) surfaces shows preferential incorporation of As in the - vicinal faces relative to + vicinals. EXAFS fit results for both adsorption and coprecipitation samples confirm that As occurs in the 5+ oxidation state in tetrahedral coordination with oxygen, i.e., as arsenate. For adsorption samples, As(V) forms inner-sphere surface complexes via corner-sharing with Ca octahedra. As(V) coprecipitated with calcite substitutes in carbonate sites but with As off-centered, as indicated by two Ca shells, and with likely disruption of local structure. The results indicate that As(V) interacts strongly with the calcite surface, similar to often-cited analog phosphate, and uptake can occur via both adsorption and coprecipitation reactions. Therefore, calcite may be effective for partial removal of dissolved arsenate from aquatic and soil systems.

  18. Spectroscopic Characterization of Structural Changes in Membrane Scaffold Proteins Entrapped within Mesoporous Silica Gel Monoliths.

    PubMed

    Zeno, Wade F; Hilt, Silvia; Risbud, Subhash H; Voss, John C; Longo, Marjorie L

    2015-04-29

    The changes in the orientation and conformation of three different membrane scaffold proteins (MSPs) upon entrapment in sol-gel-derived mesoporous silica monoliths were investigated. MSPs were examined in either a lipid-free or a lipid-bound conformation, where the proteins were associated with lipids to form nanolipoprotein particles (NLPs). NLPs are water-soluble, disk-shaped patches of a lipid bilayer that have amphiphilic MSPs shielding the hydrophobic lipid tails. The NLPs in this work had an average thickness of 5 nm and diameters of 9.2, 9.7, and 14.8 nm. We have previously demonstrated that NLPs are more suitable lipid-based structures for silica gel entrapment than liposomes because of their size compatibility with the mesoporous network (2-50 nm) and minimally altered structure after encapsulation. Here we further elaborate on that work by using a variety of spectroscopic techniques to elucidate whether or not different MSPs maintain their protein-lipid interactions after encapsulation. Fluorescence spectroscopy and quenching of the tryptophan residues with acrylamide, 5-DOXYL-stearic acid, and 16-DOXYL-stearic acid were used to determine the MSP orientation. We also utilized fluorescence anisotropy of tryptophans to measure the relative size of the NLPs and MSP aggregates after entrapment. Finally, circular dichroism spectroscopy was used to examine the secondary structure of the MSPs. Our results showed that, after entrapment, all of the lipid-bound MSPs maintained orientations that were minimally changed and indicative of association with lipids in NLPs. The tryptophan residues appeared to remain buried within the hydrophobic core of the lipid tails in the NLPs and appropriately spaced from the bilayer center. Also, after entrapment, lipid-bound MSPs maintained a high degree of α-helical content, a secondary structure associated with protein-lipid interactions. These findings demonstrate that NLPs are capable of serving as viable hosts for functional integral membrane proteins in the synthesis of sol-gel-derived bioinorganic hybrid nanomaterials. PMID:25849085

  19. Characterization of the interactions between tetracycline antibiotics and microbial extracellular polymeric substances with spectroscopic approaches.

    PubMed

    Song, Chao; Sun, Xue-Fei; Xing, Su-Fang; Xia, Peng-Fei; Shi, Yi-Jing; Wang, Shu-Guang

    2014-02-01

    The antibiotics have attracted global attentions for their impact on aquatic ecosystem. The knowledge about the fate of antibiotics encountering extracellular polymeric substances (EPS) is, however, limited. In this study, we investigated the interacting mechanisms of tetracycline (TC) to EPS extracted from aerobic activated sludge. The contributions of the main components of EPS, extracellular proteins, and polysaccharides were evaluated using bovine serum albumin and alginate sodium, respectively. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and nuclear magnetic resonance indicated that hydroxyl, carboxyl, and amino groups were the domain chemical groups involved in the interaction between TC and EPS, and the binding of TC onto EPS changed the structure of these chemical groups, thus causing shifts in their UV-visible absorption spectra. In addition, we found that extracellular proteins, rather than polysaccharides, were the major active contents involved in the interaction. Three-dimensional excitation-emission matrix fluorescence spectroscopy showed that the fluorophores in EPS were clearly quenched by TC and the static quenching process was observed, implying the complex formation of TC and EPS. Furthermore, thermodynamic analysis indicated that the binding of TC with EPS is spontaneous and dominated by electrostatic forces. PMID:23979850

  20. Spectroscopic characterization of C2Hx intermediates in the dissociation of vinyl iodide on Pt(111)

    NASA Astrophysics Data System (ADS)

    Ren, Yuan; Waluyo, Iradwikanari; Yin, Jun; Trenary, Michael

    2015-07-01

    The thermal decomposition of vinyl iodide on Pt(111) was studied using reflection absorption infrared spectroscopy (RAIRS). Some of the vinyl iodide molecularly desorbs at 160 K and the remainder decomposes via scission of the C-I bond to form vinyl. In this way, the vibrational signature of vinyl on Pt(111) is directly determined by RAIRS. At 190 K, vinyl starts to convert to di-? bonded ethylene. The ethylene undergoes further reaction at 230 K to hydrogenate to ethylidene, possibly by way of a vinyl intermediate. Upon annealing the surface to 300 K, ethylidene is converted to ethylidyne. Hydrogen pre-adsorption promotes the cleavage of the C-I bond of vinyl iodide and the formation of vinyl, which subsequently leads to an increase in the amount of di-? bonded ethylene formed. The surface hydrogen enhances the formation of ethylidyne, possibly by removal of excess ethylidene by hydrogenation, as ethylidene was not observed when hydrogen was pre-adsorbed on the surface.

  1. Combined X-Ray and Raman Spectroscopic Techniques for the Characterization of Sea Spray Aerosol

    NASA Astrophysics Data System (ADS)

    Aller, J. Y.; Alpert, P. A.; Knopf, D. A.; Kilthau, W.; Bothe, D.; Charnawskas, J. C.; Gilles, M. K.; OBrien, R. E.; Moffet, R.; Radway, J.

    2014-12-01

    Sea spray aerosol along with mineral dust dominates the global mass flux of particles to the atmosphere. Marine aerosol particles are of particular interest because of their continual impact on cloud formation, precipitation, atmospheric chemical processes, and thus global climate. Here we report on the physical/chemical characteristics of sub-surface waters, aerosolized sea spray particles, and particles/organic species present in surface microlayer (SML) samples collected during oceanic field campaigns and generated during laboratory experiments, revealing a biogenic primary source of the organic fraction of airborne particles. We also report on ice nucleation experiments with aerosolized particles collected during the May 2014 WACS II North Atlantic cruise and with laboratory generated exudate material from diatom cultures with the potential to impact cirrus and mixed phase clouds. Physicochemical analyses using a multi-modal approach which includes Scanning Transmission X-ray Microscopy coupled with Near-Edge Absorption Fine Structure Spectroscopy (STXM/NEXAFS) and Raman spectroscopy confirm the presence and chemical similarity of polysaccharide-rich transparent exopolymer (TEP) material and proteins in both SML sea spray aerosol and ice forming aerosol particles, regardless of the extent of biological activity in surface waters. Our results demonstrate a direct relationship between the marine environment and composition of marine aerosol through primary particle emission.

  2. Chemical leaching of an Indian bituminous coal and characterization of the products by vibrational spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Manoj, B.; Kunjomana, A. G.

    2012-04-01

    High volatile bituminous coal was demineralized by a chemical method. The vibrations of the "aromatics" structure of graphite, crystalline or non-crystalline, were observed in the spectra at the 1600 cm-1 region. The band at 1477 cm-1 is assigned as VR band, the band at 1392 cm-1 as VL band and the band at 1540 cm-1 as GR band. Graphite structure remains after chemical leaching liberates oxygenated functional groups and mineral groups. The silicate bands between 1010 and 1100 cm-1 are active in the infrared (IR) spectrum but inactive in the Raman spectrum. Absorption arising from C-H stretching in alkenes occurs in the region of 3000 to 2840 cm-1. Raman bands because of symmetric stretch of water molecules were also observed in the spectrum at 3250 cm-1 and 3450 cm-1. Scanning electron microscopy analysis revealed the presence of a graphite layer on the surface. Leaching of the sample with hydrofluoric acid decreases the mineral phase and increases the carbon content. The ash content is reduced by 84.5wt% with leaching from its initial value by mainly removing aluminum and silicate containing minerals.

  3. Spectroscopic Characterization of Intermediates in the Iron Catalyzed Activation of Alkanes

    SciTech Connect

    Edward M. Eyring

    2007-05-28

    The present report begins with a brief survey of recent hypervalent iron chemistry and mentions two previously reported ferrate papers funded by the DOE/BES grant. The focus is then shifted to the seven publications acknowledging support of the grant that have not been reported since the last Progress Report, DOE/ER/14340-9, was prepared. These papers deal with: (a) the successful use of an ATR element in a stopped-flow infrared spectrometer, (b) the rationalization of a depolarization of a LiClO4 solution in polyethylene oxide high polymer, (c) an analysis of several coupled ultrasonic relaxations observed in solutions of pentoses undergoing isomerization, (d) the combination of ultrasonic absorption and Raman scattering measurements to elucidate zinc thiocyanate solutions in water, (e) the use of NMR to determine stability constants when LiClO4:12-crown-4 is dissolved in acetonitrile and in methanol, (f) the possible existence of triple ions in low permittivity solutions, and (g) the properties of a high surface area ceria aerogel. Collectively, these papers illustrate advantages of bringing several modern experimental techniques to bear on complex chemical systems.

  4. Spectroscopic Characterization of a Monomeric, Cyclopentadienyl-Based Rhenium(V) Dioxo Complex.

    PubMed

    Raju, Suresh; Jastrzebski, Johann T B H; Lutz, Martin; Witteman, Léon; Dethlefsen, Johannes R; Fristrup, Peter; Moret, Marc-Etienne; Gebbink, Robertus J M Klein

    2015-11-16

    Mononuclear, coordinatively unsaturated rhenium(V) dioxo species of the type XReO2 (X = Me, substituted cyclopentadienyl) have long been postulated as intermediates in rhenium-catalyzed deoxydehydration, but their characterization was precluded because of aggregation into dimeric or oligomeric structures. Using the bulky 1,2,4-tri-tert-butylcyclopentadienyl (Cp(ttt)) ligand, the rhenium(V) dioxo species (Cp(ttt))ReO2 could now be observed, in equilibrium with the dimeric form [(Cp(ttt))Re(O)μ-O]2, and characterized by NMR, IR, and UV-vis spectroscopies, as well as electrospray ionization mass spectrometry. (Cp(ttt))ReO2 is shown to be the primary product of reduction of the rhenium(VII) complex (Cp(ttt))ReO3 with PPh3 and demonstrated to react with ethylene glycol significantly faster than its dimeric counterpart, supporting its role as an intermediate in rhenium-catalyzed deoxydehydration reactions. PMID:26517008

  5. Accurate spectroscopic characterization of ethyl mercaptan and dimethyl sulfide isotopologues: a route toward their astrophysical detection

    SciTech Connect

    Puzzarini, C.; Senent, M. L.; Domínguez-Gómez, R.; Carvajal, M.; Hochlaf, M.; Al-Mogren, M. Mogren E-mail: senent@iem.cfmac.csic.es E-mail: miguel.carvajal@dfa.uhu.es E-mail: mmogren@ksu.edu.sa

    2014-11-20

    Using state-of-the-art computational methodologies, we predict a set of reliable rotational and torsional parameters for ethyl mercaptan and dimethyl sulfide monosubstituted isotopologues. This includes rotational, quartic, and sextic centrifugal-distortion constants, torsional levels, and torsional splittings. The accuracy of the present data was assessed from a comparison to the available experimental data. Generally, our computed parameters should help in the characterization and the identification of these organo-sulfur molecules in laboratory settings and in the interstellar medium.

  6. Theoretical spectroscopic characterization at low temperatures of methyl hydroperoxide and three S-analogs

    SciTech Connect

    Dalbouha, S. Senent, M. L.; Komiha, N.

    2015-02-21

    The low temperature spectra of the detectable species methyl hydroperoxide (CH{sub 3}OOH) and three sulfur analogs, the two isomers of methanesulfenic acid (CH{sub 3}SOH and CH{sub 3}OSH) and the methyl hydrogen disulfide (CH{sub 3}SSH), are predicted from highly correlated ab initio methods (CCSD(T) and CCSD(T)-F12). Rotational parameters, anharmonic frequencies, torsional energy barriers, torsional energy levels, and their splittings are provided. Our computed parameters should help for the characterization and the identification of these organic compounds in laboratory and in the interstellar medium.

  7. Theoretical spectroscopic characterization at low temperatures of methyl hydroperoxide and three S-analogs

    NASA Astrophysics Data System (ADS)

    Dalbouha, S.; Senent, M. L.; Komiha, N.

    2015-02-01

    The low temperature spectra of the detectable species methyl hydroperoxide (CH3OOH) and three sulfur analogs, the two isomers of methanesulfenic acid (CH3SOH and CH3OSH) and the methyl hydrogen disulfide (CH3SSH), are predicted from highly correlated ab initio methods (CCSD(T) and CCSD(T)-F12). Rotational parameters, anharmonic frequencies, torsional energy barriers, torsional energy levels, and their splittings are provided. Our computed parameters should help for the characterization and the identification of these organic compounds in laboratory and in the interstellar medium.

  8. LCVD-grown micro carbon rod for MEMS applications: a study on the Raman spectroscopic characterization

    NASA Astrophysics Data System (ADS)

    Selvan, Jayaraman S.; Jeong, Sungho

    2002-11-01

    We have fabricated micro carbon rod/needle structures of size 30 to 400 ?m on graphite substrate by the pyrolytic decomposition of ethylene precursor gas using argon ion laser (514.5 nm) at different laser power and chamber pressure. The micro carbon rods were characterized using Raman spectroscopy and two broad peaks centered at 1320-1345 cm-1 and 1589-1602 cm-1 were observed, which corresponds to D (disorder) and G (graphitic) bands, respectively. LCVD grown micro carbon rods consists of highly polycrystalline graphite as well as amorphous carbon phase. The microstructural features of the LCVD grown micro carbon rods are discussed in detail.

  9. Full elastic characterization of absorptive rubber using laser excited guided ultrasonic waves

    NASA Astrophysics Data System (ADS)

    Verstraeten, Bert; Xu, Xiadong; Martinez, Loc; Glorieux, Christ

    2012-05-01

    Because of the highly damping nature of rubber, it is difficult to characterize its dynamic elastic properties using classical methods. In this paper, an experimental approach employing laser excited guided acoustic waves is proposed to accurately determine the real and imaginary part of the longitudinal and shear elastic modulus of a rubber layer. From the spatiotemporal evolution of a propagating laser excited Lamb wave measured by a laser Doppler vibrometer, which is scanning along a line perpendicular to a line of excitation, the phase velocity dispersion curves in the wave number - frequency domain are obtained. The results are interpreted in the framework of a detailed semianalytical study, analyzing the influence of elastic damping on the Lamb dispersion curves. This analysis is exploited to adequately fit the experimental dispersion curves and thus extract information about the elastic moduli and absorption coefficients of the rubber plate. The results are validated by a pulse-echo measurement, and by guided wave propagation results with the rubber layer connected in a bi-layer plate configuration to non-damping plates.

  10. Meso-Scale Modeling to Characterize Moisture Absorption of 3D Woven Composite

    NASA Astrophysics Data System (ADS)

    Yuan, Yuan; Zhou, Chu-wei

    2016-03-01

    For polymer-matrix composites, moisture is expected to degrade their mechanical properties due to matrix plasticization and moisture introduced micro-scale defects. In this study, the moisture absorptions of bulk epoxy, unidirectional composite (UD) and 3D woven composite (3D WC) were tested. Two-stage features have been observed for all these three materials. Moisture properties for UD and 3D WC were found not in simple direct proportion to their matrix volume fractions. The moisture approach of UD was modeled including the effect of fiber/matrix interphase which promotes the moisture uptake. Then, meso-scale FE model for 3D WC was established to characterize the inhomogeneous moisture diffusion. The moisture properties of resin-rich region and fiber bundle in 3D WC were determined from water uptake experiments of bulk epoxy and UD, respectively. Through homogenizing moisture properties of surface and interior weave structures, a simplified theoretical sandwich moisture diffusion approach was established. The moisture weight gains of 3D WC predicted by both meso-scale FE model and simplified sandwich approach were well agreed with the experimental data.

  11. Synthesis, spectroscopic characterization, biological screenings, DNA binding study and POM analyses of transition metal carboxylates.

    PubMed

    Uddin, Noor; Sirajuddin, Muhammad; Uddin, Nizam; Tariq, Muhammad; Ullah, Hameed; Ali, Saqib; Tirmizi, Syed Ahmed; Khan, Abdur Rehman

    2015-04-01

    This article contains the synthesis of a novel carboxylic acid derivative, its transition metal complexes and evaluation of biological applications. Six carboxylate complexes of transition metals, Zn(II) and Hg(II), have been successfully synthesized and characterized by FT-IR and NMR (1H, 13C). The ligand, HL, (4-[(2,6-Diethylphenyl)amino]-4-oxobutanoic acid) was also characterized by single crystal X-ray analysis. The complexation occurs via oxygen atoms of the carboxylate moiety. FT-IR date show the bidentate nature of the carboxylate moiety of the ligand as the ?? value in all complexes is less than that of the free ligand. The ligand and its complexes were screened for antifungal and antileishmanial activities. The results showed that the ligand and its complexes are active with few exceptions. UV-visible spectroscopy and viscometry results reveal that the ligand and its complexes interact with the DNA via intercalative mode of interaction. A new and efficient strategy to identify the pharmacophores and anti-pharmacophores sites in carboxylate derivatives for the antibacterial/antifungal activity using Petra, Osiris and Molinspiration (POM) analyses was also carried out. PMID:25646895

  12. Synthesis, spectroscopic characterization, biological screenings, DNA binding study and POM analyses of transition metal carboxylates

    NASA Astrophysics Data System (ADS)

    Uddin, Noor; Sirajuddin, Muhammad; Uddin, Nizam; Tariq, Muhammad; Ullah, Hameed; Ali, Saqib; Tirmizi, Syed Ahmed; Khan, Abdur Rehman

    2015-04-01

    This article contains the synthesis of a novel carboxylic acid derivative, its transition metal complexes and evaluation of biological applications. Six carboxylate complexes of transition metals, Zn(II) and Hg(II), have been successfully synthesized and characterized by FT-IR and NMR (1H, 13C). The ligand, HL, (4-[(2,6-Diethylphenyl)amino]-4-oxobutanoic acid) was also characterized by single crystal X-ray analysis. The complexation occurs via oxygen atoms of the carboxylate moiety. FT-IR date show the bidentate nature of the carboxylate moiety of the ligand as the ?? value in all complexes is less than that of the free ligand. The ligand and its complexes were screened for antifungal and antileishmanial activities. The results showed that the ligand and its complexes are active with few exceptions. UV-visible spectroscopy and viscometry results reveal that the ligand and its complexes interact with the DNA via intercalative mode of interaction. A new and efficient strategy to identify the pharmacophores and anti-pharmacophores sites in carboxylate derivatives for the antibacterial/antifungal activity using Petra, Osiris and Molinspiration (POM) analyses was also carried out.

  13. Structural and spectroscopic characterization of Mo 1-xW xO 3- ? mixed oxides

    NASA Astrophysics Data System (ADS)

    Morandi, S.; Paganini, M. C.; Giamello, E.; Bini, M.; Capsoni, D.; Massarotti, V.; Ghiotti, G.

    2009-12-01

    Mo 1-xW xO 3 oxides with different cationic fraction ( x=0.2, 0.5 and 0.8) and, for comparison purposes, pure MoO 3 and WO 3 were prepared. Along with textural and structural characterizations, absorbance FT-IR, diffuse reflectance UV-vis-NIR and EPR spectroscopies were employed to study the changes in the electronic properties of these materials passing from Mo 1-xW xO 3 in oxidizing atmosphere to Mo 1-xW xO 3-? in reducing conditions. XRD analysis showed that the Mo-W mixed oxides are constituted by two or three crystalline phases, whose abundance and composition are well characterized by structural refinement with the Rietveld method. Only the sample with the highest Mo content ( x=0.2) shows a predominant mixed phase and also a superior ability to lose oxygen with respect to the other mixed oxides. The oxygen loss in the reduced oxides induces the formation of defects with electronic levels in the band gap of the material, in particular, electrons trapped in oxygen vacancies and/or at cationic sites (polarons). While the nature of defect sites induced in the mixed and in the pure oxides is similar, the photo-ionization energies, the ratio between surface and bulk defects and the stability of the defects in oxygen at increasing temperature are peculiar of each mixed oxide.

  14. Spectroscopic characterization of metal complexes of novel Schiff base. Synthesis, thermal and biological activity studies

    NASA Astrophysics Data System (ADS)

    Omar, M. M.; Mohamed, Gehad G.; Ibrahim, Amr A.

    2009-07-01

    Novel Schiff base (HL) ligand is prepared via condensation of 4-aminoantipyrine and 2-aminobenzoic acid. The ligand is characterized based on elemental analysis, mass, IR and 1H NMR spectra. Metal complexes are reported and characterized based on elemental analyses, IR, 1H NMR, solid reflectance, magnetic moment, molar conductance and thermal analyses (TGA, DrTGA and DTA). The molar conductance data reveal that all the metal chelates are non-electrolytes. IR spectra show that HL is coordinated to the metal ions in a uninegatively tridentate manner with NNO donor sites of the azomethine N, amino N and deprotonated caroxylic-O. From the magnetic and solid reflectance spectra, it is found that the geometrical structures of these complexes are octahedral. The thermal behaviour of these chelates shows that the hydrated complexes losses water molecules of hydration in the first step followed immediately by decomposition of the anions and ligand molecules in the subsequent steps. The activation thermodynamic parameters, such as, E*, ΔH*, ΔS* and ΔG* are calculated from the DrTG curves using Coats-Redfern method. The synthesized ligands, in comparison to their metal complexes also were screened for their antibacterial activity against bacterial species, Escherichia Coli, Pseudomonas aeruginosa, Staphylococcus Pyogones and Fungi (Candida). The activity data show that the metal complexes to be more potent/antibacterial than the parent Shciff base ligand against one or more bacterial species.

  15. Solvate Structures and Computational/Spectroscopic Characterization of LiBF4 Electrolytes

    SciTech Connect

    Seo, D. M.; Boyle, Paul D.; Allen, Joshua L.; Han, Sang D.; Jonsson , Erlendur; Johansson, Patrik; Henderson, Wesley A.

    2014-07-21

    Crystal structures have been determined for both LiBF4 and HBF4 solvates―(acetonitrile)2:LiBF4, (ethylene glycol diethyl ether)1:LiBF4, (diethylene glycol diethyl ether)1:LiBF4, (tetrahydrofuran)1:LiBF4, (methyl methoxyacetate)1:LiBF4, (suc-cinonitrile)1:LiBF4, (N,N,N',N",N"-pentamethyldiethylenetriamine)1:HBF4, (N,N,N',N'-tetramethylethylenediamine)3/2:HBF4 and (phenanthroline)2:HBF4. These, as well as other known LiBF4 solvate structures, have been characterized by Raman vibrational spectroscopy to unambiguously assign the anion Raman band positions to specific forms of BF4-...Li+ cation coordination. In addition, complementary DFT calculations of BF4-...Li+ cation complexes have provided additional insight into the challenges associated with accurately interpreting the anion interactions from experimental Raman spectra. This information provides a crucial tool for the characterization of the ionic association interactions within electrolytes.

  16. Spectroscopic and kinetic characterization of the light-dependent enzyme protochlorophyllide oxidoreductase (POR) using monovinyl and divinyl substrates.

    PubMed

    Heyes, Derren J; Kruk, Jerzy; Hunter, C Neil

    2006-02-15

    The enzyme POR [Pchlide (protochlorophyllide) oxidoreductase] catalyses the reduction of Pchlide to chlorophyllide, which is a key step in the chlorophyll biosynthesis pathway. This light-dependent reaction has previously been studied in great detail but recent reports suggest that a mixture of MV (monovinyl) and DV (divinyl) Pchlides may have influenced some of these properties of the reaction. Low-temperature absorbance and fluorescence spectroscopy have revealed several spectral differences between MV and DV Pchlides, which were purified from a Rhodobacter capsulatus strain that was shown to contain a mixture of the two pigments. A thorough steady-state kinetic characterization using both Pchlide forms demonstrates that neither pigment appears to affect the kinetic properties of the enzyme. The reaction has also been monitored following illumination at low temperatures and was shown to consist of an initial photochemical step followed by four 'dark' steps for both pigments. However, minor differences were observed in the spectral properties of some of the intermediates, although the temperature dependency of each step was nearly identical for the two pigments. This work provides the first detailed kinetic and spectroscopic study of this unique enzyme using biologically important MV and DV substrate analogues. It also has significant implications for the DV reductase enzyme, which is responsible for converting DV pigments into their MV counterparts, and its position in the sequence of reactions that comprise the chlorophyll biosynthesis pathway. PMID:16274361

  17. Synthesis, spectroscopic characterization and biological activity of cis-[Ru(hesperidin)(1,10?-phenanthroline)2](PF6) complex

    NASA Astrophysics Data System (ADS)

    Oliveira, Regina M. M.; de Souza Daniel, Juliana F.; Carlos, Rose M.

    2013-01-01

    The new complex cis-[Ru(phen)2(hesperidin)](PF6), complex 1, was synthesized and characterized by analytical (ESI-MS+, EA (C, H, N)) and spectroscopic (FTIR, UV-vis, 1H and 13C NMR) techniques and cyclic voltammetry. Complex 1 is chemically stable in the solid state and in organic solvents such as ethanol, methanol, acetone, and acetonitrile, as shown by spectrophotometric analysis. 1 is also photochemically and chemically stable (pH effects) and more hydrosoluble (518.83 0.91 g mL-1) than free hesperidin (5.92 g mL-1). In accordance with this, the lipophilicity value in aqueous-octanol solution for 1 was -1.28, indicating its high hydrophilic characteristic. Although complex 1 showed to be essentially noncytotoxic, IC50 > 1.0 mmol L-1 as evaluated in the human cervical cancer cells line HeLa, it exhibited a moderate capacity of inhibiting the catalytic activity of the acetylcholinaesterase enzyme, IC50 = 63.6 mol L-1. The Lineweaver-Burk plot and the respective secondary replot indicated that the AChE inhibition was noncompetitive and reversible. These findings shows that complexation of the hesperidin improves physicochemical characteristics and increases the perspectives for development and medical applications of new bioactive-metal complexes.

  18. Structures and spectroscopic characterization of calcium chloride-nicotinamide, -isonicotinamide, -picolinamide and praseodymium bromide-nicotinamide complexes.

    PubMed

    Xue, Junhui; Jiang, Ye; Li, Weihong; Yang, Limin; Xu, Yizhuang; Zhao, Guozhong; Zhang, Gaohui; Bu, Xiaoxia; Liu, Kexin; Chen, Jia'er; Wu, Jinguang

    2015-02-25

    The coordination structures formed by calcium complexes with nicotinamide (na), isonicotinamide (ina) and picolinamide (pa) and praseodymium bromide-na are reported. The structures of CaCl2(C6H6N2O)22H2O (Ca-na), CaCl2(C6H6N2O)24H2O (Ca-ina), CaCl2(C6H6N2O)25H2O (Ca-pa) and PrBr3(C6H6N2O)26H2O (PrBr-na) in the solid state have been characterized by X-ray single crystal diffraction, FTIR, FIR, THz and Raman spectroscopies. Carbonyl oxygen of nicotinamide is coordinated to Ca(2+), but it is O-monodentate (carbonyl oxygen) and N,O-bidentate ligand (pyridyl nitrogen and carbonyl oxygen) for Pr(3+) to form a chain structure in PrBr-na. For isonicotinamide, only carbonyl oxygen atom is coordinated to Ca(2+). Pyridyl nitrogen and carbonyl oxygen of picolinamide are coordinated to Ca(2+) to form a five-membered ring structure. The crystal structure and spectroscopic results indicate the differences of the coordination of Ca and Pr ions, the changes of hydrogen bonds and conformation of the ligands induced by complexation. Unlike transition metal ions, Sr(2+) or lanthanide ions, Ca(2+) is inclined to coordinate to carbonyl oxygen atoms of the ligands. PMID:25280333

  19. Synthesis, spectroscopic, structural characterization, electrochemical and antimicrobial activity studies of the Schiff base ligand and its transition metal complexes

    NASA Astrophysics Data System (ADS)

    Aslanta?, Mehmet; Kendi, Engin; Demir, Necmettin; ?abik, Ali E.; Tmer, Mehmet; Kertmen, Metin

    2009-10-01

    In this study, the Schiff base ligand trans-N,N'-bis[(2,4-dichlorophenyl) methylidene] cyclohexane-1,2-diamine (L) and its copper(II), nickel(II) and palladium(II) transition metal complexes were prepared and characterized by the analytical and spectroscopic methods. The 1H( 13C) NMR spectra of the ligand and its diamagnetic complexes were recorded in DMSO-d 6 solvent and obtained data confirm that the nitrogen atoms of the imine groups coordinated to the metal ions. Electrochemical properties of the ligand and its metal complexes were investigated in the DMF solvent at the 100 and 250 mV s -1 scan rates. The ligand and metal complexes showed both reversible and irreversible processes at these scan rates. The single crystal of the ligand (L) was obtained from MeOH solution, and its crystal structure was determined by X-ray diffraction. The C-H⋯Cl hydrogen bonding interactions in the molecule were seen which increase the stability of the crystal structure. The antimicrobial activity studies of the ligand and its metal complexes were carried out by using the various bacteria and fungi.

  20. Synthesis, characterization and multi-spectroscopic DNA interaction studies of a new platinum complex containing the drug metformin.

    PubMed

    Shahabadi, Nahid; Heidari, Leila

    2014-07-15

    A new platinum(II) complex; [Pt(Met)(DMSO)Cl]Cl in which Met = metformin and DMSO: dimethylsulfoxide, was synthesized and characterized by (1)H NMR, IR, UV-Vis spectra, molar conductivity and computational methods. Binding interaction of this complex with calf thymus (CT) DNA has been investigated by using absorption, emission, circular dichroism, viscosity measurements, differential pulse voltammetry and cleavage studies by agarose gel electrophoresis. UV-Vis absorption studies showed hyperchromism. CD studies showed less perturbation on the base stacking and helicity bands in the CD spectrum of CT-DNA (B?C structural transition). In fluorimeteric studies, the Pt(II) complex can bind with DNA-NR complex and forms a new non-fluorescence adduct. The anodic peak current in the differential pulse voltammogram of the Pt(II) complex decreased gradually with the addition of DNA. Cleavage experiments showed that the Pt(II) complex does not induce any cleavage under the experimental setup. Finally all results indicated that Pt(II) complex interact with DNA via groove binding mode. PMID:24682051

  1. Synthesis, characterization and multi-spectroscopic DNA interaction studies of a new platinum complex containing the drug metformin

    NASA Astrophysics Data System (ADS)

    Shahabadi, Nahid; Heidari, Leila

    2014-07-01

    A new platinum(II) complex; [Pt(Met)(DMSO)Cl]Cl in which Met = metformin and DMSO: dimethylsulfoxide, was synthesized and characterized by 1H NMR, IR, UV-Vis spectra, molar conductivity and computational methods. Binding interaction of this complex with calf thymus (CT) DNA has been investigated by using absorption, emission, circular dichroism, viscosity measurements, differential pulse voltammetry and cleavage studies by agarose gel electrophoresis. UV-Vis absorption studies showed hyperchromism. CD studies showed less perturbation on the base stacking and helicity bands in the CD spectrum of CT-DNA (B ? C structural transition). In fluorimeteric studies, the Pt(II) complex can bind with DNA-NR complex and forms a new non-fluorescence adduct. The anodic peak current in the differential pulse voltammogram of the Pt(II) complex decreased gradually with the addition of DNA. Cleavage experiments showed that the Pt(II) complex does not induce any cleavage under the experimental setup. Finally all results indicated that Pt(II) complex interact with DNA via groove binding mode.

  2. Spectroscopic characterization of a masterpiece: The Manueline foral charter of Sintra

    NASA Astrophysics Data System (ADS)

    Manso, Marta; Gac, Agnès Le; Longelin, Stéphane; Pessanha, Sofia; Frade, José Carlos; Guerra, Mauro; Candeias, António José; Carvalho, Maria Luísa

    2013-03-01

    The foral charter attributed by D. Manuel I of Portugal, in 1514, to the village of Sintra was studied using Energy Dispersive X-ray Fluorescence spectrometry, Raman and Infrared micro-spectroscopies. A complete characterization of the pictorial materials used in the production of this masterpiece allowed the identification of iron gall inks used in the written text; pigments such as malachite, azurite, lead white, cinnabar, yellow ochre, gold, silver and carbon black in the illuminations and letterings; filler and binder used in the production of coloring materials and inks. Gum and calcium carbonate were the most recurrent binder and filler identified in this study. Silvering and gilding were mostly obtained by applying ground silver and gold on parchment.

  3. Spectroscopic characterization of discharge products in Li-Air cells with aprotic carbonate electrolytes

    SciTech Connect

    Veith, Gabriel M; Nanda, Jagjit; Howe, Jane Y; Dudney, Nancy J

    2011-01-01

    Raman, infrared and X-ray photoelectron spectroscopies were used to characterize the thick coating of reaction products on carbon and MnO2 coated carbon cathodes produced during discharge of Li-air cells. The results show that neither Li2O2 or Li2O are major components of the insoluble discharge products; instead the products are largely composed of fluorine, lithium, and carbon, with surprisingly little oxygen. The complex reaction chemistry also appears to involve the formation of ethers or alkoxide products at the expense of the carbonate solvent molecules (ethylene carbonate and dimethylcarbonate). The irreversible discharge reaction is likely electrochemically promoted with Li-anion species and dissolved oxygen. Exactly how the molecular O2 participates in the reaction is unclear and requires further study. The addition of a conformal coating of MnO2 on the carbon lowers the cell s operating voltage, but does not alter the overall discharge chemistry.

  4. Structural and spectroscopic characterizations of tetra-nuclear niobium(V) complexes of quinolinol derivatives

    NASA Astrophysics Data System (ADS)

    Amini, Mostafa M.; Fazaeli, Yousef; Mohammadnezhad, Gholamhossein; Khavasi, Hamid Reza

    2015-06-01

    Reactions between niobium ethoxide and 8-hydroxy-2-methylquinoline or 5-chloro-8-hydroxyquinoline have been explored. Two new tetranuclear heteroleptic niobium complexes containing oxo, ethoxo, and quinolinate chelate rings have been synthesized and characterized by 1H, 13C and 93Nb NMR, UV-Vis, and FT-IR spectroscopies, and single-crystal X-ray diffraction. The molecular structures of the niobium complexes, [Nb4(?-O)4(?-OEt)2(ONC10H8)2(OEt)8] (I) and [Nb4(?-O)4(?-OEt)2(ONC9H5Cl)2(OEt)8] (II), are composed of a pair of edge-sharing bioctahedral moieties in which connected via two almost linear oxo-bridges, with a large difference in the NbO distances. Single-crystal structures showed both complexes are centrosymmetric and contain two distinct Nb centers, and results confirmed by observation of two niobium signals in the 93Nb NMR spectra of complexes.

  5. Raman spectroscopic characterization of the core-rim structure in reaction bonded boron carbide ceramics

    SciTech Connect

    Jannotti, Phillip; Subhash, Ghatu; Zheng, James Q.; Halls, Virginia; Karandikar, Prashant G.; Salamone, S.; Aghajanian, Michael K.

    2015-01-26

    Raman spectroscopy was used to characterize the microstructure of reaction bonded boron carbide ceramics. Compositional and structural gradation in the silicon-doped boron carbide phase (rim), which develops around the parent boron carbide region (core) due to the reaction between silicon and boron carbide, was evaluated using changes in Raman peak position and intensity. Peak shifting and intensity variation from the core to the rim region was attributed to changes in the boron carbide crystal structure based on experimental Raman observations and ab initio calculations reported in literature. The results were consistent with compositional analysis determined by energy dispersive spectroscopy. The Raman analysis revealed the substitution of silicon atoms first into the linear 3-atom chain, and then into icosahedral units of the boron carbide structure. Thus, micro-Raman spectroscopy provided a non-destructive means of identifying the preferential positions of Si atoms in the boron carbide lattice.

  6. Raman Spectroscopic Characterization of Packaged L. pneumophila Strains Expelled by T. thermophila.

    PubMed

    Kusi?, Dragana; Ramoji, Anuradha; Neugebauer, Ute; Rsch, Petra; Popp, Jrgen

    2016-03-01

    The intracellular lifestyle of L. pneumophila within protozoa is considered to be a fundamental process that supports its survival in nature. However, after ingesting the cells of L. pneumophila, some protozoa expel them as compressed live cells in the form of small rounded pellets. The pellets of tightly packaged viable but not culturable forms (VBNCFs) as well as highly infectious mature intracellular forms (MIFs) of L. pneumophila are considered as infectious particles most likely capable to cause human infection. Since L. pneumophila cells are hardly culturable from these pellets, detection methods for packaged live L.pneumophila forms remaining in water should be cultivation free. Hence, we demonstrate the potential of Raman microspectroscopy to directly sort pellets containing L. pneumophila cells, expelled by T.thermophila, and to characterize them on the basis of their Raman spectra. PMID:26853973

  7. Ipolamiide and fulvoipolamiide from Stachytarpheta glabra (Verbenaceae): A structural and spectroscopic characterization

    NASA Astrophysics Data System (ADS)

    Viccini, Lyderson F.; Silva, Pmela S.; Almeida, Mauro V. de; Saraiva, Maurcio F.; Peixoto, Paulo Henrique P.; Salimena, Ftima Regina G.; Diniz, Renata; Rodrigues, Bernardo L.; Scowen, Ian; Edwards, Howell G. M.; Oliveira, Luiz F. C. de

    2008-03-01

    The phenylethanoid glycoside acteoside and the iridoids ipolamiide and 4-methoxycarbonyl-7-methylcyclopenta[ c]pyran (fulvoipolamiide) were isolated from the leaves of Stachytarpheta glabra. The solid state structure of fulvoipolamiide was confirmed by X-ray diffraction studies. The molecules of fulvoipolamiide are displayed in layers parallel to the crystallographic axis a. This molecule is planar with electron delocalization in the fused ring system and the pyran rings of adjacent layers in the solid state structure are involved in a ?-? stacking interaction. Raman spectroscopy has also been used to characterize the most important bands present in the spectra of fulvoipolamiide and ipolamiide, and comparison made with literature allows the assignment of some key markers, specially the bands in the 1600-1700 cm -1 range.

  8. Spectroscopic characterization of magnetic Fe3O4@Au core shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Fouad, Dina M.; El-Said, Waleed A.; Mohamed, Mona B.

    2015-04-01

    The magnetic nanoparticles iron oxide (Fe3O4) nanoparticles and iron oxide/gold core-shell (Fe3O4/Au) nanoparticles were synthesized and their catalytic photo-degradation activity towards malathion as example of organophosphorus pesticides were reported. Iron oxide (Fe3O4) magnetic nanoparticle was successfully prepared through co-precipitation method by the reduction of ferric chloride (FeCl3) using ascorbic acid. The morphology of the prepared nanoparticles was characterized by the TEM and XRD (X-ray diffraction) techniques. Degradation of 10 ppm of malathion in the presence of these nanoparticles under UV radiation was monitored using (HPLC) and UV-visible spectra. Fe3O4/Au nanoparticles showed higher efficiency in photo-degradation of malathion than Fe3O4 ones.

  9. Synthesis and spectroscopic characterization of gold nanobipyramids prepared by a chemical reduction method

    NASA Astrophysics Data System (ADS)

    Thanh Ngo, Vo Ke; Phat Huynh, Trong; Giang Nguyen, Dang; Phuong Uyen Nguyen, Hoang; Lam, Quang Vinh; Dat Huynh, Thanh

    2015-12-01

    Gold nanobipyramids (NBPs) have attracted much attention because they have potential for applications in smart sensing devices, such as medical diagnostic equippments. This is due to the fact that they show more advantageous plasmonic properties than other gold nanostructures. We describe a chemical reduction method for synthesizing NBPs using conventional heating with ascorbic acid reduction and cetyltrimethylamonium bromide (CTAB) + AgNO3 as capping agents. The product was characterized by ultravioletvisible spectroscopy (UVvis), Fourier transmission infrared spectroscopy (FTIR), transmission electron microscopy (TEM), x-ray powder diffraction (XRD). The results showed that gold nanoparticles were formed with bipyramid shape (tip-to-tip distance of 88.4 9.4 nm and base length of 29.9 3.2 nm) and face-centered-cubic crystalline structure. Optimum parameters for preparation of NBPs are also found.

  10. Laboratory studies of spectroscopic markers for the characterization of surface erosion by plasmas

    SciTech Connect

    Manos, D.M.; Bennett, T.; Herzer, M.; Schwarzmann, J.

    1992-01-01

    The erosion rates in portions of fusion plasma devices like the ITER tokamak are sufficiently high that nearly real-time information on cumulative removal is needed for control and machine safety. We are developing a digitally--encoded scheme to indicate the depth of erosion at numerous poloidal and toroidal locations around ITER. The scheme uses materials embedded in the walls and divertors, which, when uncovered, present remotely detectable signals. This paper reports laboratory experiments on prototype markers consisting of combinations of up to 5 elements (Au,Pd,Ag,In,Ga) along with Au,Pt, and Ta pure metals. The markers were bonded to 4-D carbon-carbon composite of the type proposed for use in the ITER first wall, and placed in the lower-hybrid-driven plasma of the atomic beam facility at PPL. The paper describes this device Light emission was characterized using a 1 meter Czerny-Turner vacuum ultraviolet monochromator. The samples were characterized both before and after plasma exposure by Auger spectroscopy. We report the time-dependent behavior of the spectra of the visible and ultraviolet light emitted by the plasma when the markers are uncovered by the erosion showing emission lines of the marker elements which are easily distinguished from the background plasma lines. The dependence of the light intensity on bias voltage is compared to the known sputtering yields of the elements. The optical detection method allows exploration of the threshold dependence of these multi-element targets. An exponential dependence of yield above threshold was observed for all of the elements studied.

  11. Laboratory studies of spectroscopic markers for the characterization of surface erosion by plasmas

    SciTech Connect

    Manos, D.M.; Bennett, T.; Herzer, M.; Schwarzmann, J.

    1992-06-01

    The erosion rates in portions of fusion plasma devices like the ITER tokamak are sufficiently high that nearly real-time information on cumulative removal is needed for control and machine safety. We are developing a digitally--encoded scheme to indicate the depth of erosion at numerous poloidal and toroidal locations around ITER. The scheme uses materials embedded in the walls and divertors, which, when uncovered, present remotely detectable signals. This paper reports laboratory experiments on prototype markers consisting of combinations of up to 5 elements (Au,Pd,Ag,In,Ga) along with Au,Pt, and Ta pure metals. The markers were bonded to 4-D carbon-carbon composite of the type proposed for use in the ITER first wall, and placed in the lower-hybrid-driven plasma of the atomic beam facility at PPL. The paper describes this device Light emission was characterized using a 1 meter Czerny-Turner vacuum ultraviolet monochromator. The samples were characterized both before and after plasma exposure by Auger spectroscopy. We report the time-dependent behavior of the spectra of the visible and ultraviolet light emitted by the plasma when the markers are uncovered by the erosion showing emission lines of the marker elements which are easily distinguished from the background plasma lines. The dependence of the light intensity on bias voltage is compared to the known sputtering yields of the elements. The optical detection method allows exploration of the threshold dependence of these multi-element targets. An exponential dependence of yield above threshold was observed for all of the elements studied.

  12. Spectroscopic characterization and the coordination behavior of isonicotinamide with lanthanide ions

    NASA Astrophysics Data System (ADS)

    Xue, Junhui; Hua, Xiaohui; Yang, Limin; Xu, Yizhuang; Li, Weihong; Zhao, Guozhong; Zhang, Gaohui; Wu, Jinguang

    2013-11-01

    The coordination of amide groups to metal ions is important because it may be involved in the interactions between metal ions and proteins. The synthesis and characterization of nine novel lanthanide-isonicotinamide (ina) complexes, including LaCl3, PrCl3, NdCl3, SmCl3, EuCl3, GdCl3, TbCl3, ErCl3 and PrBr3 complexes are reported. The structures of these complexes in the solid state have been characterized by X-ray single crystal diffraction, FTIR, FIR, THz and Luminescence spectroscopy. Isonicotinamide has only one coordination mode in four structures as O-monodentate ligand to coordinate to metal ions, but four kinds of topological structures are observed for lanthanide-isonicotinamide complexes, including LnCl3?(C6H6N2O)2?4H2O (La, Pr, Nd and Sm), EuCl3?(C6H6N2O)2?7H2O, LnCl3?(C6H6N2O)2?6H2O (Gd, Tb and Er) and PrBr3?(C6H6N2O)2?7H2O. Chloride ions can coordinate to metal ions or hydrogen-bonded. FTIR spectra indicate the formation of four kinds of lanthanide-ina complexes, the extensive hydrogen bond networks after complexation and the coordinations and the changes of the conformation of the ligand. FIR and THz spectra also confirm the formation of lanthanide ion-ina complexes. Luminescence spectra of Eu and Tb-ina complexes have the characteristics of Eu and Tb ions.

  13. CSP Spectroscopic Classification of AT 2016adj in NGC 5128 (Centaurus A)

    NASA Astrophysics Data System (ADS)

    Stritzinger, M.; Hsiao, E. Y.; Morrell, N.; Phillips, M. M.; Contreras, C.; Castellón, S.; Clocchiatti, A.

    2016-02-01

    We report spectroscopic classification of AT 2016adj (cf. ATEL #8651) based on a visual-wavelength spectrum obtained on Feb. 9.2 UT with the 2.5-m du Pont Telescope (+ WFCCD) at LCO. The spectrum exhibits prevalent Na-I D absorption at the redshift of NGC 5128 characterized by an equivalent width of 0.44-nm.

  14. Theoretical spectroscopic characterization at low temperatures of detectable sulfur-organic compounds: ethyl mercaptan and dimethyl sulfide.

    PubMed

    Senent, M L; Puzzarini, C; Domnguez-Gmez, R; Carvajal, M; Hochlaf, M

    2014-03-28

    Highly correlated ab initio methods are used for the spectroscopic characterization of ethyl mercaptan (CH3CH2 (32)SH, ETSH) and dimethyl sulfide (CH3 (32)SCH3, DMS), considering them on the vibrational ground and excited torsional states. Since both molecules show non-rigid properties, torsional energy barriers and splittings are provided. Equilibrium geometries and the corresponding rotational constants are calculated by means of a composite scheme based on CCSD(T) calculations that accounts for the extrapolation to the complete basis set limit and core-correlation effects. The ground and excited states rotational constants are then determined using vibrational corrections obtained from CCSD/cc-pVTZ force-field calculations, which are also employed to determine anharmonic frequencies for all vibrational modes. CCSD(T) and CCSD force fields are employed to predict quartic and sextic centrifugal-distortion constants, respectively. Equilibrium rotational constants are also calculated using CCSD(T)-F12. The full-dimensional anharmonic analysis does not predict displacements of the lowest torsional excited states due to Fermi resonances with the remaining vibrational modes. Thus, very accurate torsional transitions are calculated by solving variationally two-dimensional Hamiltonians depending on the CH3 and SH torsional coordinates of ethyl mercaptan or on the two methyl groups torsions of dimethyl-sulfide. For this purpose, vibrationally corrected potential energy surfaces are computed at the CCSD(T)/aug-cc-pVTZ level of theory. For ethyl mercaptan, calculations show large differences between the gauche (g) and trans (t) conformer spectral features. Interactions between rotating groups are responsible for the displacements of the g-bands with respect to the t-bands that cannot therefore be described with one-dimensional models. For DMS, the CCSD(T) potential energy surface has been semi-empirically adjusted to reproduce experimental data. New assignments are suggested for the methyl torsion bands of ETSH and a reassignment is proposed for the infrared bands of DMS (0 3 ? 0 4 and 1 0 ? 1 1). Our accurate spectroscopic data should be useful for the analysis of the microwave and far infrared spectra of ETSH and DMS recorded, at low temperatures, either in laboratory or in the interstellar medium. PMID:24697436

  15. Theoretical spectroscopic characterization at low temperatures of detectable sulfur-organic compounds: Ethyl mercaptan and dimethyl sulfide

    NASA Astrophysics Data System (ADS)

    Senent, M. L.; Puzzarini, C.; Domnguez-Gmez, R.; Carvajal, M.; Hochlaf, M.

    2014-03-01

    Highly correlated ab initio methods are used for the spectroscopic characterization of ethyl mercaptan (CH3CH232SH, ETSH) and dimethyl sulfide (CH332SCH3, DMS), considering them on the vibrational ground and excited torsional states. Since both molecules show non-rigid properties, torsional energy barriers and splittings are provided. Equilibrium geometries and the corresponding rotational constants are calculated by means of a composite scheme based on CCSD(T) calculations that accounts for the extrapolation to the complete basis set limit and core-correlation effects. The ground and excited states rotational constants are then determined using vibrational corrections obtained from CCSD/cc-pVTZ force-field calculations, which are also employed to determine anharmonic frequencies for all vibrational modes. CCSD(T) and CCSD force fields are employed to predict quartic and sextic centrifugal-distortion constants, respectively. Equilibrium rotational constants are also calculated using CCSD(T)-F12. The full-dimensional anharmonic analysis does not predict displacements of the lowest torsional excited states due to Fermi resonances with the remaining vibrational modes. Thus, very accurate torsional transitions are calculated by solving variationally two-dimensional Hamiltonians depending on the CH3 and SH torsional coordinates of ethyl mercaptan or on the two methyl groups torsions of dimethyl-sulfide. For this purpose, vibrationally corrected potential energy surfaces are computed at the CCSD(T)/aug-cc-pVTZ level of theory. For ethyl mercaptan, calculations show large differences between the gauche (g) and trans (t) conformer spectral features. Interactions between rotating groups are responsible for the displacements of the g-bands with respect to the t-bands that cannot therefore be described with one-dimensional models. For DMS, the CCSD(T) potential energy surface has been semi-empirically adjusted to reproduce experimental data. New assignments are suggested for the methyl torsion bands of ETSH and a reassignment is proposed for the infrared bands of DMS (0 3 ? 0 4 and 1 0 ? 1 1). Our accurate spectroscopic data should be useful for the analysis of the microwave and far infrared spectra of ETSH and DMS recorded, at low temperatures, either in laboratory or in the interstellar medium.

  16. Spectroscopic characterization of extracellular polymeric substances from a mixed culture dominated by ammonia-oxidizing bacteria.

    PubMed

    Yin, Cuiqin; Meng, Fangang; Chen, Guang-Hao

    2015-01-01

    Extracellular polymeric substances (EPS) of aerobic (AerAOB) and anaerobic ammonium-oxidizing bacteria (AnAOB) are expected to have a significant impact on the performance of autotrophic nitrogen removal in engineered systems. However, there are a few investigations of the EPS of AerAOB and AnAOB, and the results are contradictory. In this study, photometric measurements indicated that the EPS of AerAOB- (31.74 1.48 mg/g-VSS, volatile suspended solids) and AnAOB-enriched cultures (30.12 1.52 mg/g-VSS) contained more polysaccharides than did conventional activated sludge from a municipal wastewater treatment facility (10.76 0.83 mg/g-VSS). In addition, the EPS of the AnAOB-enriched culture was dominated by proteins, leading to a considerably higher protein/polysaccharide ratio (2.64 0.12) than those of the AerAOB-enriched culture (0.56 0.03) and conventional activated sludge (1.96 0.09). Characterization using Fourier transform infrared spectroscopy (FTIR) revealed the dominance of amide bands and/or polysaccharide-associated bands in the EPS of AnAOB and AerAOB. These results corroborate the data from the photometric measurements. In addition, the EPS of AnAOB (23.1% 1.2%) and AerAOB (21.9% 1.1%) had a higher portion of ?-helices, which is the key protein secondary structure that determines flocculation or cell aggregation, in the amide I band than that of activated sludge (16.7% 0.8%). X-ray photoelectron spectroscopy (XPS) characterization also revealed significantly different functionalities among the EPS of the three mixed cultures; e.g., O-(C,H), which indicates the presence of polysaccharides, was richer in the EPS of AerAOB, whereas protonated amines, which are commonly found in amino acids and amino sugars, accounted for a large portion of the EPS of AnAOB. The results of this study can potentially expand our knowledge of the microbial aggregates responsible for autotrophic nitrogen removal. PMID:25462778

  17. Synthesis, characterization and spectroscopic studies of some boron-containing hydrogen storage materials

    NASA Astrophysics Data System (ADS)

    Jash, Panchatapa

    In this dissertation the synthesis and characterization of boron-related nanostructures and dehydrogenation studies of metal borohydrides using FTIR are reported. Boron-related nanostructures are of interest because of their potential applications in nanoelectronics and in hydrogen storage. A low pressure chemical vapor deposition (LPCVD) apparatus was built in order to grow boron nanostructures. Various techniques, namely, Auger electron spectroscopy (AES), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy were used to characterize the synthesized boron and boride nanostructures, and boron coated carbon nanotubes (CNTs). By the uncatalyzed pyrolysis of diborane, at relatively low temperature, crystalline boron nanoribbons were synthesized. Nickel-catalyzed growth also produced Ca, Sr and Y boride nanowires that were found to be crystalline. Amorphous boron coated CNTs were synthesized by LPCVD. Two growth mechanisms, vapor-liquid-solid (VLS) and vapor-solid (VS) were invoked to explain the observed nanostructures. A high vacuum apparatus for FTIR studies was built. The capabilities of the apparatus were first tested by acquiring low temperature and room temperature spectra of sodium and lithium borohydrides. The metal borohydrides are of high hydrogen content and dehydrogenation studies using FTIR were done. NaBH 4 and the K2B12H12 salt were studied. It was found that above its melting point (673 K), NaBH4 is probably converted to its B12H12-2 salt, which then loses all hydrogen to produce amorphous boron. This conversion of B 12H12-2 to boron clusters was confirmed through dehydrogenation studies of K2B12H12. Both SIMS and AES are surface sensitive techniques to study thin film surfaces and interfaces at nano-dimentions. Thin (9-10 mum) cadmium telluride films have application as the buffer layer on silicon substrates to form high quality mercury cadmium telluride (MCT) films. MCT films find applications in IR detectors and in photovoltaic cells. Due to the lattice mismatch it is necessary to grow CdTe films on a monolayer of arsenic and 20 nm thick ZnTe on silicon. The purpose of this study was to show the capabilities of the Scanning Auger Multiprobe PHI 600 in the qualitative analysis of CdTe, ZnTe and As films on Si and of an MCT film surface, which was grown on CdZnTe.

  18. Infrared spectroscopic characterization of the interaction of cationic lipids with plasmid DNA.

    PubMed

    Choosakoonkriang, S; Wiethoff, C M; Anchordoquy, T J; Koe, G S; Smith, J G; Middaugh, C R

    2001-03-16

    Fourier transform infrared spectroscopy was used to characterize the interaction of the cationic lipids 1,2-dioleoyl-3-trimethylammonium-propane and dioctadecyldimethylammonium bromide with plasmid DNA. The effect of incorporating the neutral colipids cholesterol and dioleoylphosphatidylethanolamine on this interaction was also examined. Additionally, dynamic and phase analysis light scattering were used to monitor the size and zeta potential of the resulting complexes under conditions similar to the Fourier transform infrared measurements. Results suggest that upon interaction of cationic lipids with DNA, the DNA remains in the B form. Distinct changes in the frequency of several infrared bands arising from the DNA bases, however, suggest perturbation of their hydration upon interaction with cationic lipids. A direct interaction of the lipid ammonium headgroup with and dehydration of the DNA phosphate is observed when DNA is complexed with these lipids. Changes in the apolar regions of the lipid bilayer are minimal, whereas the interfacial regions of the membrane show changes in hydration or molecular packing. Incorporation of helper lipids into the cationic membranes results in increased conformational disorder of the apolar region and further dehydration of the interfacial region. Changes in the hydration of the DNA bases were also observed as the molar ratio of helper lipid in the membranes was increased. PMID:11118456

  19. New copper(II) complexes with dopamine hydrochloride and vanillymandelic acid: Spectroscopic and thermal characterization

    NASA Astrophysics Data System (ADS)

    Mohamed, Gehad G.; Nour El-Dien, F. A.; El-Nahas, R. G.

    2011-10-01

    The dopamine derivatives participate in the regulation of wide variety of physiological functions in the human body and in medication life. Increase and/or decrease in the concentration of dopamine in human body reflect an indication for diseases such as Schizophrenia and/or Parkinson diseases. The Cu(II) chelates with coupled products of dopamine hydrochloride (DO.HCl) and vanillymandelic acid (VMA) with 4-aminoantipyrine (4-AAP) are prepared and characterized. Different physico-chemical techniques namely IR, magnetic and UV-vis spectra are used to investigate the structure of these chelates. Cu(II) forms 1:1 (Cu:DO) and 1:2 (Cu:VMA) chelates. DO behave as a uninegative tridentate ligand in binding to the Cu(II) ion while VMA behaves as a uninegative bidentate ligand. IR spectra show that the DO is coordinated to the Cu(II) ion in a tridentate manner with ONO donor sites of the phenolic- OH, -NH and carbonyl- O, while VMA is coordinated with OO donor sites of the phenolic- OH and -NH. Magnetic moment measurements reveal the presence of Cu(II) chelates in octahedral and square planar geometries with DO and VMA, respectively. The thermal decomposition of Cu(II) complexes is studied using thermogravimetric (TG) and differential thermal analysis (DTA) techniques. The activation thermodynamic parameters, such as, energy of activation, enthalpy, entropy and free energy change of the complexes are evaluated and the relative thermal stability of the complexes are discussed.

  20. Spectroscopic, Structural, and Computational Characterization of Three Bispidinone Derivatives, as Ligands for Enantioselective Metal Catalyzed Reactions.

    PubMed

    Castellano, Carlo; Sacchetti, Alessandro; Meneghetti, Fiorella

    2016-04-01

    Three chiral derivatives of the alkaloid sparteine (bispidines), characterized by the 3,7-diazabicyclo[3.3.1]nonane moiety, were designed as efficient ligands in a number of enantioselective reactions due to their metal coordination properties. A full evaluation of the 3D properties of the compounds was carried out, as the geometrical features of the bicyclic framework are strictly related to the efficiency of the ligands in the asymmetric catalysis. The selected molecules have different molecular complexity for investigating the effects of different chiral groups on the bicycle conformation. We report here a thorough analysis of their molecular arrangement, by NMR spectroscopy, single crystal X-ray crystallography, and computational techniques, which put in evidence their conformational preferences and the parameters needed for the design of more efficient ligands in asymmetric synthetic routes. The results confirmed the high molecular flexibility of the compounds, and indicated how to achieve a control of the chair-chair/boat-chair conformational ratio, by adjusting the relative size of the substituents on the piperidine nitrogens. Chirality 28:332-339, 2016. © 2016 Wiley Periodicals, Inc. PMID:26899470

  1. Spectroscopic characterization of zinc oxide nanorods synthesized by solid-state reaction

    NASA Astrophysics Data System (ADS)

    Prasad, Virendra; D'Souza, Charlene; Yadav, Deepti; Shaikh, A. J.; Vigneshwaran, Nadanathangam

    2006-09-01

    Well-crystallized zinc oxide nanorods have been fabricated by single step solid-state reaction using zinc acetate and sodium hydroxide, at room temperature. The sodium lauryl sulfate (SLS) stabilized zinc oxide nanorods were characterized by using X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy and photoluminescence spectroscopy. The X-ray diffraction revealed the wurtzite structure of zinc oxide. The size estimation by XRD and TEM confirmed that the ZnO nanorods are made of single crystals. The growth of zinc oxide crystals into rod shape was found to be closely related to its hexagonal nature. The mass ratio of SLS:ZnO in the nanorods was found to be 1:10 based on the thermogravimetric analysis. Blue shift of photoluminescence emission was noticed in the ZnO nanorods when compared to that of ZnO bulk. FT-IR analysis confirmed the binding of SLS with ZnO nanorods. Apart from ease of preparation, this method has the advantage of eco-friendliness since the solvent and other harmful chemicals were eliminated in the synthesis protocol.

  2. Synthesis, spectroscopic and computational characterization of the tautomerism of pyrazoline derivatives from chalcones

    NASA Astrophysics Data System (ADS)

    Miguel, Fbio Balbino; Dantas, Juliana Arantes; Amorim, Stefany; Andrade, Gustavo F. S.; Costa, Luiz Antnio Sodr; Couri, Mara Rubia Costa

    2016-01-01

    In the present study a series of novel pyrazolines derivatives has been synthesized, and their structures assigned on the basis of FT-Raman, 1H and 13C NMR spectral data and computational DFT calculations. A joint computational study using B3LYP/6-311G(2d,2p) density functional theory and FT-Raman investigation on the tautomerism of 3-(4-substituted-phenyl)-4,5-dihydro-5-(4-substituted-phenyl)pyrazole-1-carbothioamide and 3-(4-substituted-phenyl)-4,5-dihydro-5-(4-substituted-phenyl)pyrazole-1-carboxamide are presented. The structures were characterized as a minimum in the potential energy surface using DFT. The calculated Raman and NMR spectra were of such remarkable agreement to the experimental results that the equilibrium between tautomeric forms has been discussed in detail. Our study suggests the existence of tautomers, the carboxamide/carbothioamide group may tautomerize, in the solid state or in solution. Thermodynamic data calculated suggests that the R(Cdbnd S)NH2 and R(Cdbnd O)NH2 species are more stable than the R(Cdbnd NH)SH and R(Cdbnd NH)OH species. Additionally, results found for the 1H NMR shifting, pointed out to which structure is present.

  3. Synthesis, spectroscopic and computational characterization of the tautomerism of pyrazoline derivatives from chalcones.

    PubMed

    Miguel, Fbio Balbino; Dantas, Juliana Arantes; Amorim, Stefany; Andrade, Gustavo F S; Costa, Luiz Antnio Sodr; Couri, Mara Rubia Costa

    2016-01-01

    In the present study a series of novel pyrazolines derivatives has been synthesized, and their structures assigned on the basis of FT-Raman, (1)H and (13)C NMR spectral data and computational DFT calculations. A joint computational study using B3LYP/6-311G(2d,2p) density functional theory and FT-Raman investigation on the tautomerism of 3-(4-substituted-phenyl)-4,5-dihydro-5-(4-substituted-phenyl)pyrazole-1-carbothioamide and 3-(4-substituted-phenyl)-4,5-dihydro-5-(4-substituted-phenyl)pyrazole-1-carboxamide are presented. The structures were characterized as a minimum in the potential energy surface using DFT. The calculated Raman and NMR spectra were of such remarkable agreement to the experimental results that the equilibrium between tautomeric forms has been discussed in detail. Our study suggests the existence of tautomers, the carboxamide/carbothioamide group may tautomerize, in the solid state or in solution. Thermodynamic data calculated suggests that the R(CS)NH2 and R(CO)NH2 species are more stable than the R(CNH)SH and R(CNH)OH species. Additionally, results found for the (1)H NMR shifting, pointed out to which structure is present. PMID:26232575

  4. Spectroscopic characterization and molecular modeling of novel palladium(II) complexes with carbazates and hydrazides

    NASA Astrophysics Data System (ADS)

    Sousa, L. M.; Corbi, P. P.; Formiga, A. L. B.; Lancellotti, Marcelo; Marzano, I. M.; Pereira-Maia, E. C.; Von Poelhsitz, G.; Guerra, W.

    2015-10-01

    Palladium(II) complexes of the type trans-[Pd(L)2Cl2], where L = 4-methoxybenzylcarbazate (4-MC), benzyl carbazate (BC), 4-fluorophenoxyacetic acid hydrazide (4-FH), 3-methoxybenzoic acid hydrazide (3-MH), ethyl carbazate (EC) and tert-butyl carbazate (TC) were synthesized by the slow addition of the ligand to K2PdCl4 previously dissolved in water or ethanol. These complexes were characterized by elemental analyses, conductivity measurements, TG/DTA, FT-IR, mass spectrometric and NMR spectroscopy (solution and solid-state). All coordination compounds exhibit a square planar coordination geometry in which the palladium(II) ion coordinates to two nitrogen atoms and two chlorine atoms. The structures of the palladium(II) complexes were optimized and theoretical data show that the trans isomer is more stable, in accordance with the experimental data. Preliminary in vitro tests of some these new palladium complexes in a chronic myelogenous leukemia cell line (k562 cells) are also reported.

  5. Minor groove binding of the food colorant carmoisine to DNA: spectroscopic and calorimetric characterization studies.

    PubMed

    Basu, Anirban; Kumar, Gopinatha Suresh

    2014-01-01

    The interaction of the food additive carmoisine with herring testes DNA was studied by multifaceted biophysical techniques. Carmoisine exhibited hypochromic effects in absorbance, whereas in fluorescence the intensity enhanced upon complexation with DNA. Energy transfer from the DNA base pairs to carmoisine molecules occurred upon complexation. A groove binding model of interaction was envisaged for carmoisine-DNA complexation from 4',6-diamidino-2-phenylindole (DAPI) and Hoechst displacement studies. The binding of carmoisine stabilized the DNA structure against thermal denaturation. The binding induced moderate conformational perturbations in the B-form structure of DNA. The binding affinity (10(4) M(-1)) values, calculated from absorbance and fluorescence data, and calorimetry titrations were in close agreement with each other. The binding was characterized to be exothermic and favored by small negative enthalpic and large positive entropic contributions. Salt-dependent calorimetric studies revealed that the binding reaction was dominated by nonpolyelectrolytic forces. The negative heat capacity value suggested the role of hydrophobic effect in the interaction. PMID:24328331

  6. Spectroscopic characterization of zinc oxide nanorods synthesized by solid-state reaction.

    PubMed

    Prasad, Virendra; D'Souza, Charlene; Yadav, Deepti; Shaikh, A J; Vigneshwaran, Nadanathangam

    2006-09-01

    Well-crystallized zinc oxide nanorods have been fabricated by single step solid-state reaction using zinc acetate and sodium hydroxide, at room temperature. The sodium lauryl sulfate (SLS) stabilized zinc oxide nanorods were characterized by using X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy and photoluminescence spectroscopy. The X-ray diffraction revealed the wurtzite structure of zinc oxide. The size estimation by XRD and TEM confirmed that the ZnO nanorods are made of single crystals. The growth of zinc oxide crystals into rod shape was found to be closely related to its hexagonal nature. The mass ratio of SLS:ZnO in the nanorods was found to be 1:10 based on the thermogravimetric analysis. Blue shift of photoluminescence emission was noticed in the ZnO nanorods when compared to that of ZnO bulk. FT-IR analysis confirmed the binding of SLS with ZnO nanorods. Apart from ease of preparation, this method has the advantage of eco-friendliness since the solvent and other harmful chemicals were eliminated in the synthesis protocol. PMID:16458053

  7. Structural and spectroscopic characterizations of tetra-nuclear niobium(V) complexes of quinolinol derivatives.

    PubMed

    Amini, Mostafa M; Fazaeli, Yousef; Mohammadnezhad, Gholamhossein; Khavasi, Hamid Reza

    2015-06-01

    Reactions between niobium ethoxide and 8-hydroxy-2-methylquinoline or 5-chloro-8-hydroxyquinoline have been explored. Two new tetranuclear heteroleptic niobium complexes containing oxo, ethoxo, and quinolinate chelate rings have been synthesized and characterized by (1)H, (13)C and (93)Nb NMR, UV-Vis, and FT-IR spectroscopies, and single-crystal X-ray diffraction. The molecular structures of the niobium complexes, [Nb4(μ-O)4(μ-OEt)2(ONC10H8)2(OEt)8] (I) and [Nb4(μ-O)4(μ-OEt)2(ONC9H5Cl)2(OEt)8] (II), are composed of a pair of edge-sharing bioctahedral moieties in which connected via two almost linear oxo-bridges, with a large difference in the NbO distances. Single-crystal structures showed both complexes are centrosymmetric and contain two distinct Nb centers, and results confirmed by observation of two niobium signals in the (93)Nb NMR spectra of complexes. PMID:25756687

  8. Infrared spectroscopic characterization of carbonated apatite: a combined experimental and computational study.

    PubMed

    Ren, Fuzeng; Ding, Yonghui; Leng, Yang

    2014-02-01

    A combined experimental and computational approach was employed to investigate the feasibility and effectiveness of characterizing carbonated apatite (CAp) by infrared (IR) spectroscopy. First, an experimental comparative study was conducted to identify characteristic IR vibrational bands of carbonate substitution in the apatite lattice. The IR spectra of pure hydroxyapatite (HA), carbonate adsorbed on the HA surface, a physical mixture of HA and sodium carbonate monohydrate, a physical mixture of HA and calcite, synthetic CAps prepared using three methods (precipitation method, hydrothermal route, and solid-gas reaction at high temperature) and biological apatites (human enamel, human cortical bone, and two animal bones) were compared. Then, the IR vibrational bands of carbonate in CAp were calculated with density functional theory. The experimental study identified characteristic IR bands of carbonate that cannot be generated from surface adsorption or physical mixtures and the results show that the bands at ?880, 1413, and 1450 cm(-1) should not be used as characteristic bands of CAp since they could result from carbonate adsorbed on the apatite crystals surface or present as a separate phase. The combined experimental and computational study reveals that the carbonate v3 bands at ?1546 and 1465 cm(-1) are, respectively, the IR signature bands for type A CAp and type B CAp. PMID:23533194

  9. Spectroscopic Characterizations of Molecularly-Linked Gold Nanoparticle Assemblies Upon Thermal Treatment

    SciTech Connect

    Luo, Jin; Maye, Mathew M.; Han, Li; Kariuki, Nancy N.; Jones, V W.; Lin, Yuehe; Engelhard, Mark H.; Zhong, Chuan-Jian

    2004-05-11

    Nanostructured gold catalysts have attracted increasing interest since the pioneer work of Haruta which demonstrated unusually high catalytic activities for CO oxidation when the nanoparticles were made less than {approx}10 nm diameter in size and supported on oxides. It is possible to use core-shell gold nanoparticles to construct the catalyst and activate the catalytic activity by applying a thermal-treatment process. The understanding of how the core-shell surface components reconstitute in such a catalytic activation process will have important implications in expanding this approach to the design and fabrication of nanostructured catalysts. We report herein the results of a study of decanethiolate-capped gold nanoparticles of 2-nm and 5-nm core sizes assembled on planar substrates using 1,9-nonanedithiol (NDT) and 11-mercaptoundecanoic acid (MUA) as molecular linkers were studied as a model system. XPS and IR are employed to detect the identity of surface species and to analyze the elemental composition or oxidation states of the nanomaterials, from which we derive structural information about the surface reconstitution of the core-shell nanostructured catalysts. Electrochemical methods are used to characterize the electrocatalytic activities.

  10. Raman, infrared and near-infrared spectroscopic characterization of the herderite-hydroxylherderite mineral series

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; Scholz, Ricardo; López, Andrés; Xi, Yunfei; Queiroz, Camila de Siqueira; Belotti, Fernanda M.; Filho, Mauro Cândido

    2014-01-01

    Natural single-crystal specimens of the herderite-hydroxylherderite series from Brazil, with general formula CaBePO4(F,OH), were investigated by electron microprobe, Raman, infrared and near-infrared spectroscopies. The minerals occur as secondary products in granitic pegmatites. Herderite and hydroxylherderite minerals show extensive solid solution formation. The Raman spectra of hydroxylherderite are characterized by bands at around 985 and 998 cm-1, assigned to ν1 symmetric stretching mode of the HOPO33- and PO43- units. Raman bands at around 1085, 1128 and 1138 cm-1 are attributed to both the HOP and PO antisymmetric stretching vibrations. The set of Raman bands observed at 563, 568, 577, 598, 616 and 633 cm-1 are assigned to the ν4 out of plane bending modes of the PO4 and H2PO4 units. The OH Raman stretching vibrations of hydroxylherderite were observed ranging from 3626 cm-1 to 3609 cm-1. The infrared stretching vibrations of hydroxylherderites were observed between 3606 cm-1 and 3599 cm-1. By using a Libowitzky type function, hydrogen bond distances based upon the OH stretching bands were calculated. Characteristic NIR bands at around 6961 and 7054 cm-1 were assigned to the first overtone of the fundamental, whilst NIR bands at 10,194 and 10,329 cm-1 are assigned to the second overtone of the fundamental OH stretching vibration. Insight into the structure of the herderite-hydroxylherderite series is assessed by vibrational spectroscopy.

  11. Spectroscopic characterization of B/KNO3 diode-laser induced combustion.

    PubMed

    Sivan, J; Haas, Y

    2013-11-21

    The combustion of a B/KNO3 pyrotechnic mixture was characterized by its chemiluminescence for the first time. The reaction was initiated by a continuous wave (cw) diode laser inside a novel multipurpose reaction cell, whose design and construction are described. As in the case of the extensively studied oxidation of boron by O2, the most intense luminescence, recorded in the 400-600 nm range, is assigned to BO2. Its appearance delay time (10(-2) to 10(-1) s) equals that measured for the pressure increase and is shortened as the laser power is increased. A band observed at 355 nm appears at longer delay times than the BO2 bands. The band, and some weaker ones, may be assigned to BO, although some bands expected for BO (based on reaction between B atoms and O2) are absent from the spectra. This observation is discussed in the text, and possible emission from BN is discussed. If the band is assigned to BO, the absence of known bands may be due to specific E-V resonance energy transfer. Possible oxidation mechanisms consistent with the different delay ignition times are discussed. PMID:23679891

  12. Cytotoxic behavior and spectroscopic characterization of metal complexes of ethylacetoacetate bis(thiosemicarbazone) ligand

    NASA Astrophysics Data System (ADS)

    El-Tabl, Abdou Saad; El-wahed, Moshira Mohamed Abd; Rezk, Ahmed Mahmoud Salah Mahmoud

    2014-01-01

    Reaction of Cr(III), Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) ion with 2,4-dihydrazino-thioamido-1-ethoxybutane led to the formation of mono and binuclear complexes. These complexes have been characterized by elemental analyses, IR, UV-Vis spectra, magnetic moments, molar conductances, 1H NMR and mass spectra (ligand and its Zn(II) complex), thermal analyses (DTA and TGA) and ESR measurements. The IR data suggest the involvement of sulfur and azomethane nitrogen atoms in coordination to the central metal ion .The Molar conductances of the complexes in DMF are commensurate with their non-ionic character. The ESR spectra of Cu(II) complexes show axial type symmetry (d(x2-y2)) ground state with covalent bond character. On the basis of spectral studies, octahedral or tetrahedral geometry has been assigned to the metal complexes. Complexes have been tested invitro against tumor cells and number of microorganisms in order to assess their antitumor and antimicrobial properties.

  13. Mononuclear metal complexes of organic carboxylic acid derivatives: Synthesis, spectroscopic characterization, thermal investigation and antimicrobial activity

    NASA Astrophysics Data System (ADS)

    Abd El-Wahab, Zeinab H.

    2007-05-01

    Two Schiff base ligands bearing organic acid moiety, vis., N-(2-thienylmethylidene)-2-amino-4-chlorobenzoic acid (HL 1) and N-(2-hydroxybenzylidene)-2-amino-4-chlorobenzoic acid (H 2L 2) have been synthesized by the interaction of 2-thiophenecarboxaldehyde and 2-hydroxybenzaldehyde with 2-amino-4-chlorobenzoic acid. Co(II), Ni(II), Cu(II) and Zn(II) complexes of these ligands have been prepared. They are characterized on the basis of analytical data, molar conductance, IR, 1H NMR, UV-vis, mass spectra, magnetic measurements, thermal analysis and X-ray powder diffraction technique. The molar conductance data reveal that these complexes are non-electrolytes. The ligands are coordinated to the metal ions in a terdentate manner with ONO/ONS donor sites of the carbonyl oxygen, azomethine nitrogen and phenolic oxygen or thiophenic sulphur. An octahedral structure is proposed for the prepared metal complexes and some ligand field parameters ( Dq, B and ?) in addition to CFSE were calculated. The thermal stability of the metal complexes is evaluated. The Schiff base ligands and their metal complexes have been tested against four species of bacteria as well as four species of fungi and the results have been compared with some known antibiotics.

  14. Characterization of butyrate-dependent electroneutral Na-Cl absorption in the rat distal colon.

    TOXLINE Toxicology Bibliographic Information

    Binder HJ; Mehta P

    1990-12-01

    Recent studies have established that mucosal butyrate stimulates electroneutral sodium-chloride (Na-Cl) absorption in the distal colon of the rat and a model in which Na-hydrogen (H) and Cl-butyrate exchanges are coupled has been proposed as the mechanism of butyrate-dependent electroneutral Na-Cl absorption. These studies were designed to examine butyrate-dependent electroneutral Na-Cl absorption in experimental conditions in which HCO3-dependent electroneutral Na-Cl absorption is inhibited: in Na-depleted (aldosterone-treated) animals and in the presence of increased mucosal cyclic adenosine monophosphate (AMP). Butyrate-dependent electroneutral Na-Cl absorption was markedly reduced in Na-depleted rats. In contrast, the inhibition of both net Na and net Cl absorption by 5 mM serosal theophylline was significantly less in butyrate-containing, HCO3-free Ringer solution than in butyrate-free- HCO3-containing Ringer solution. These studies indicate that cyclic AMP does not inhibit butyrate-dependent electroneutral Na-Cl absorption and we propose that the mechanism of cyclic AMP inhibition of HCO3-dependent electroneutral Na-Cl absorption may be a result of its inhibition of Cl-HCO3, not Na-H exchange.

  15. Characterization of butyrate-dependent electroneutral Na-Cl absorption in the rat distal colon.

    PubMed

    Binder, H J; Mehta, P

    1990-12-01

    Recent studies have established that mucosal butyrate stimulates electroneutral sodium-chloride (Na-Cl) absorption in the distal colon of the rat and a model in which Na-hydrogen (H) and Cl-butyrate exchanges are coupled has been proposed as the mechanism of butyrate-dependent electroneutral Na-Cl absorption. These studies were designed to examine butyrate-dependent electroneutral Na-Cl absorption in experimental conditions in which HCO3-dependent electroneutral Na-Cl absorption is inhibited: in Na-depleted (aldosterone-treated) animals and in the presence of increased mucosal cyclic adenosine monophosphate (AMP). Butyrate-dependent electroneutral Na-Cl absorption was markedly reduced in Na-depleted rats. In contrast, the inhibition of both net Na and net Cl absorption by 5 mM serosal theophylline was significantly less in butyrate-containing, HCO3-free Ringer solution than in butyrate-free- HCO3-containing Ringer solution. These studies indicate that cyclic AMP does not inhibit butyrate-dependent electroneutral Na-Cl absorption and we propose that the mechanism of cyclic AMP inhibition of HCO3-dependent electroneutral Na-Cl absorption may be a result of its inhibition of Cl-HCO3, not Na-H exchange. PMID:2080102

  16. (TAML)Fe**IV=O Complex in Aqueous Solution: Synthesis And Spectroscopic And Computational Characterization

    SciTech Connect

    Chanda, A.; Shan, X.; Chakrabarti, M.; Ellis, W.C.; Popescu, D.L.; Oliveira, F.Tiago de; Wang, D.; Que, L.; Jr.; Collins, T.J.; Munck, E.; Bominaar, E.L.

    2009-05-12

    Recently, we reported the characterization of the S = 1/2 complex [Fe{sup V}(O)B*]{sup -}, where B* belongs to a family of tetraamido macrocyclic ligands (TAMLs) whose iron complexes activate peroxides for environmentally useful applications. The corresponding one-electron reduced species, [Fe{sup IV}(O)B*]{sup 2-} (2), has now been prepared in >95% yield in aqueous solution at pH > 12 by oxidation of [Fe{sup III}(H{sub 2}O)B*]{sup -} (1), with tert-butyl hydroperoxide. At room temperature, the monomeric species 2 is in a reversible, pH-dependent equilibrium with dimeric species [B*Fe{sup IV}?O?Fe{sup IV}B*]{sup 2-} (3), with a pK{sub a} near 10. In zero field, the Moessbauer spectrum of 2 exhibits a quadrupole doublet with {Delta}E{sub Q} = 3.95(3) mm/s and {delta} = ?0.19(2) mm/s, parameters consistent with a S = 1 Fe{sup IV} state. Studies in applied magnetic fields yielded the zero-field splitting parameter D = 24(3) cm{sup -1} together with the magnetic hyperfine tensor A/g{sub n}{beta}{sub n} = (?27, ?27, +2) T. Fe K-edge EXAFS analysis of 2 shows a scatterer at 1.69 (2) {angstrom}, a distance consistent with a Fe{sup IV} = O bond. DFT calculations for [Fe{sup IV}(O)B*]{sup 2-} reproduce the experimental data quite well. Further significant improvement was achieved by introducing hydrogen bonding of the axial oxygen with two solvent-water molecules. It is shown, using DFT, that the {sup 57}Fe hyperfine parameters of complex 2 give evidence for strong electron donation from B* to iron.

  17. Osmium NAMI-A analogues: synthesis, structural and spectroscopic characterization, and antiproliferative properties.

    PubMed

    Cebrin-Losantos, Berta; Krokhin, Artem A; Stepanenko, Iryna N; Eichinger, Rene; Jakupec, Michael A; Arion, Vladimir B; Keppler, Bernhard K

    2007-06-11

    The osmium(III) complex [(DMSO)2H][trans-OsIIICl4(DMSO)2] (1) has been prepared via stepwise reduction of OsO4 in concentrated HCl using N2H(4).2HCl and SnCl(2).2H2O in DMSO. 1 reacts with a number of azole ligands, namely, indazole (Hind), pyrazole (Hpz), benzimidazole (Hbzim), imidazole (Him), and 1H-1,2,4-triazole (Htrz), in organic solvents, affording novel complexes (H2ind)[OsIIICl4(Hind)(DMSO)] (2), (H2pz)[OsIIICl4(Hpz)(DMSO)] (3), (H2bzim)[OsIIICl4(Hbzim)(DMSO)] (4), (H2im)[OsIIICl4(Him)(DMSO)] (6), and (H2trz)[OsIIICl4(Htrz)(DMSO)] (7), which are close analogues of the antimetastatic complex NAMI-A. Metathesis reaction of 4 with benzyltriphenylphosphonium chloride in methanol led to the formation of (Ph3PCH2Ph)[OsIIICl4(Hbzim)(DMSO)] (5). The complexes were characterized by IR, UV-vis, ESI mass spectrometry, 1H NMR spectroscopy, cyclic voltammetry, and X-ray crystallography. In contrast to NAMI-A, 2-4, 6, and 7 are kinetically stable in aqueous solution and resistant to hydrolysis. Surprisingly, they show reasonable antiproliferative activity in vitro in two human cell lines, HT-29 (colon carcinoma) and SK-BR-3 (mammary carcinoma), when compared with analogous ruthenium compounds. Structure-activity relationships and the potential of the prepared complexes for further development are discussed. PMID:17497853

  18. Structural and spectroscopic characterization of ettringite mineral -combined DFT and experimental study

    NASA Astrophysics Data System (ADS)

    Scholtzov, Eva; Kuckov, Lenka; Koek, Jozef; Tunega, Daniel

    2015-11-01

    The structure of the ettringite mineral was studied by means of FTIR spectroscopy and single crystal X-ray diffraction method. The experimental study was combined with the first principle calculations based on density functional theory (DFT) method. Predicted structural parameters (unit cell vectors and positions of heavy atoms) are in a very good agreement with the experimental data. Moreover, calculations also enabled to refine the positions of the hydrogen atoms not determined precisely by the single crystal X-ray measurement. The detailed analysis of the hydrogen bonds in the ettringite structure was performed and several groups of the hydrogen bonds were classified. It was found that the water molecules from the coordination sphere of Ca2+ cations act as proton donors in moderate O-HO hydrogen bonds with SO 32- anions. Further, multiple O-HO hydrogen bonds were identified among water molecules themselves. In addition, also hydroxyl groups from the [Al(OH)6]3- octahedral units are involved in the weak O-HO hydrogen bonding with the water molecules. The calculated vibrational spectrum showed all typical features observed in the experimental FTIR spectrum. Moreover, performing the analysis of the calculated spectrum, all vibrational modes were distinguished and assigned. Such a complete analysis of the measured IR and/or Raman spectra is not fully possible, specifically for the region below 1500cm-1, which is characterized by a complex curve with many overlapped bands. A comparison of the vibrational spectra of ettringite and thaumasite (mineral structurally similar to ettringite) revealed the origin of the most important differences between them.

  19. Raman, infrared and near-infrared spectroscopic characterization of the herderite-hydroxylherderite mineral series.

    PubMed

    Frost, Ray L; Scholz, Ricardo; López, Andrés; Xi, Yunfei; Queiroz, Camila de Siqueira; Belotti, Fernanda M; Cândido Filho, Mauro

    2014-01-24

    Natural single-crystal specimens of the herderite-hydroxylherderite series from Brazil, with general formula CaBePO4(F,OH), were investigated by electron microprobe, Raman, infrared and near-infrared spectroscopies. The minerals occur as secondary products in granitic pegmatites. Herderite and hydroxylherderite minerals show extensive solid solution formation. The Raman spectra of hydroxylherderite are characterized by bands at around 985 and 998 cm(-1), assigned to ν1 symmetric stretching mode of the HOPO3(3-) and PO4(3-) units. Raman bands at around 1085, 1128 and 1138 cm(-1) are attributed to both the HOP and PO antisymmetric stretching vibrations. The set of Raman bands observed at 563, 568, 577, 598, 616 and 633 cm(-1) are assigned to the ν4 out of plane bending modes of the PO4 and H2PO4 units. The OH Raman stretching vibrations of hydroxylherderite were observed ranging from 3626 cm(-1) to 3609 cm(-1). The infrared stretching vibrations of hydroxylherderites were observed between 3606 cm(-1) and 3599 cm(-1). By using a Libowitzky type function, hydrogen bond distances based upon the OH stretching bands were calculated. Characteristic NIR bands at around 6961 and 7054 cm(-1) were assigned to the first overtone of the fundamental, whilst NIR bands at 10,194 and 10,329 cm(-1) are assigned to the second overtone of the fundamental OH stretching vibration. Insight into the structure of the herderite-hydroxylherderite series is assessed by vibrational spectroscopy. PMID:24076459

  20. Time-resolved contrast function and optical characterization of spatially varying absorptive inclusions at different depths in diffusing media.

    PubMed

    De Nicola, S; Esposito, R; Lepore, M; Indovina, P L

    2004-03-01

    The role of a spatially varying absorptive inhomogeneity located at different depths within a turbid material has been investigated. This inhomogeneity has been characterized by a spatially dependent Gaussian distribution of its absorption coefficient. The present study has been performed calculating the time-resolved contrast function in the framework of the first-order perturbative approach to the diffusion equation for a slab geometry and a coaxial measurement scheme. The model has allowed us to take into account different locations of the inclusion along the source-detector axis. The accuracy of time-resolved contrast predictions has been analyzed through comparisons with results of the finite element method that has been used to numerically solve the diffusion equation. Recovery of the absorption perturbation parameter of the inhomogeneity for different axial positions has also been investigated. PMID:15089316

  1. A New, Longitudinally Resolved, Spectroscopic Characterization of Quaoars Surface

    NASA Astrophysics Data System (ADS)

    Dalle Ore, Cristina M.; Barucci, Maria A.; Perna, Davide; Doressoundiram, Alain; Alvarez-Candal, Alvaro; Nitschelm, Christian; Cruikshank, Dale P.

    2014-11-01

    (50000) Quaoar, one of the largest Trans-neptunian objects, is comparable in size to Plutos moon Charon. However, while Charons surface is rich almost exclusively in H2O ice, Quaoars surface is characterized by ices of CH4, N2, as well as C2H6, a product of irradiation of CH4 (Dalle Ore et al. 2009). Because of its distance from the Sun, Quaoar is expected to have preserved, to a degree, its original composition, however, its relatively small size did not make it a prime candidate for presence of volatile ices in the study by Schaller and Brown (2007). Furthermore, based on the Brown et al. (2011) study its red coloration points to CH3OH as the ice which, when irradiated, might have produced the red material. We present new visible to near-infrared (0.3-2.48?m) spectro-photometric data obtained with the XSHOOTER (Vernet et al. 2011) instrument at the VLT-ESO facility at four different longitudes on the surface of Quaoar. The data are complemented by previously published photometric observations obtained in the near-infrared (3.6, 4.5?m) with the Spitzer Space Telescope, which provide an extra set of constraints in the model calculation process in spite of the different observing times that preclude establishing the spatial consistency between the two sets.For each of the four spectra we perform spectral modeling of the entire wavelength range -from 0.3 to 4.5?m- by means of a code based on the Shkuratov radiative transfer formulation of the slab model. We obtain spatially resolved compositional information for the surface of Quaoar supporting the presence of CH4 and C2H6, as previously reported, along with evidence for N2 and NH3OH. The albedo at the two Spitzer bands indicates the likely presence of CO and CO2. CH3OH, predicted on the basis of Quaoars coloration (Brown et al. 2011), is not found at any of the four longitudes, implying that the presence of this ice is a sufficient, but not necessary condition for reddening of TNO surfaces. Other ices, in particular CH4 (Brunetto et al. 2006), have been shown to be plausible precursors for reddening of TNO surfaces.

  2. Synthesis, spectroscopic characterization, and conformational properties of trichloromethanesulfenyl acetate, CCl3SOC(O)CH3.

    PubMed

    Reina, Marlene Cuaquira; Boese, Roland; Ge, Maofa; Ulic, Sonia E; Beckers, Helmut; Willner, Helge; Della Vdova, Carlos O

    2008-08-28

    Trichloromethanesulfenyl acetate, CCl 3SOC(O)CH 3, belongs to the family of sulfenic esters. This molecule has been characterized by vibrational spectroscopy. The conformational and geometrical properties of this species have been determined by IR and Raman spectroscopy, X-ray diffraction, and quantum chemical calculations. Geometry optimizations of the most stable forms were performed with ab initio (HF, MP2) and density functional theory (B3LYP) methods. According to our data, this compound results in a gauche-syn conformer with C 1 symmetry (gauche orientation around the S-O bond and syn orientation of the CO double bond with respect to the S-O single bond) for the most stable geometry, and trans-syn conformer with C s symmetry (trans orientation around the S-O bond and syn orientation of the CO double bond with respect to the S-O single bond) for the second stable conformer (1.1 and 0.53 kcal/mol higher in energy than the most stable C 1 form according to the matrix FTIR spectroscopy and MP2/6-31G* level of the theory, respectively). The crystalline solid (monoclinic, P2 1/ n, a = 8.0152(17) A, b = 5.7922(13) A, c = 17.429(4) A, alpha = gamma = 90 degrees , beta = 100.341(3) degrees ) consists exclusively of the main form. The geometrical parameters (X-ray diffraction) are d C-Cl = 1.767(19) A, d C-S = 1.797(2) A, d S-O = 1.663(14) A, d CO = 1.189(2) A, d O-C = 1.389(3) A, d C-C = 1.483(3) A, angles Cl-C-Cl = 110.3(11) degrees , Cl-C-S = 111.8(12) degrees , C-S-O = 97.4(8) degrees , S-O-C = 116.7(11) degrees , O-CO = 122.8(19) degrees , OC-C = 127.1(2) degrees , and the main torsion angles are delta(CSOC) = 105.9(15) degrees and delta(SOC(O)) = 7.6(3) degrees . The geometrical data calculated with B3LYP/6-31G++(3df,3pd), B3LYP/6-311G++(3df,3pd), B3LYP/aug-cc-pVTZ, and MP2/6-31G* are in good agreement with diffraction data. PMID:18671379

  3. Spectroscopic and Functional Characterization of Iron-Sulfur Cluster-Bound Forms of Azotobacter vinelandii NifIscA

    PubMed Central

    Mapolelo, Daphne T.; Zhang, Bo; Naik, Sunil G.; Huynh, Boi Hanh; Johnson, Michael K.

    2012-01-01

    The mechanism of [4Fe-4S] cluster assembly on A-type Fe-S cluster assembly proteins, in general, and the specific role of NifIscA in the maturation of nitrogen fixation proteins are currently unknown. To address these questions, in vitro spectroscopic studies (UVvisible absorption/CD, resonance Raman and Mssbauer) have been used to investigate the mechanism of [4Fe-4S] cluster assembly on Azotobacter vinelandii NifIscA, and the ability of NifIscA to accept clusters from NifU and to donate clusters to the apo form of the nitrogenase Fe-protein. The results show that NifIscA can rapidly and reversibly cycle between forms containing one [2Fe-2S]2+ and one [4Fe-4S]2+ cluster per homodimer via DTT-induced two-electron reductive coupling of two [2Fe-2S]2+ clusters and O2-induced [4Fe-4S]2+ oxidative cleavage. This unique type of cluster interconversion in response to cellular redox status and oxygen levels is likely to be important for the specific role of A-type proteins in the maturation of [4Fe-4S] cluster-containing proteins under aerobic growth or oxidative stress conditions. Only the [4Fe-4S]2+-NifIscA was competent for rapid activation of apo-nitrogenase Fe protein under anaerobic conditions. Apo-NifIscA was shown to accept clusters from [4Fe-4S] cluster-bound NifU via rapid intact cluster transfer, indicating a potential role as a cluster carrier for delivery of clusters assembled on NifU. Overall the results support the proposal that A-type proteins can function as carrier proteins for clusters assembled on U-type proteins and suggest that they are likely to supply [2Fe-2S] clusters rather than [4Fe-4S] for the maturation of [4Fe-4S] cluster-containing proteins under aerobic or oxidative stress growth conditions. PMID:23003323

  4. Characterization of functionalized self-assembled monolayers and surface-attached interlocking molecules using near-edge X-ray absorption fine structure spectroscopy

    NASA Astrophysics Data System (ADS)

    Willey, Trevor Michael

    Quantitative knowledge of the fundamental structure and substrate binding, as well as the direct measurement of conformational changes, are essential to the development of self-assembled monolayers (SAMs) and surface-attached interlocking molecules, catenanes and rotaxanes. These monolayers are vital to development of nano-mechanical, molecular electronic, and biological/chemical sensor applications. This dissertation investigates properties of functionalized SAMs in sulfur-gold based adsorbed molecular monolayers using quantitative spectroscopic techniques including near-edge x-ray absorption fine structure spectroscopy (NEXAFS) and x-ray photoelectron spectroscopy (XPS). The stability of the gold-thiolate interface is addressed. A simple model SAM consisting of dodecanethiol adsorbed on Au(111) degrades significantly in less than 24 hours under ambient laboratory air. S 2p and O 1s XPS show the gold-bound thiolates oxidize to sulfinates and sulfonates. A reduction of organic material on the surface and a decrease in order are observed as the layer degrades. The effect of the carboxyl vs. carboxylate functionalization on SAM structure is investigated. Carboxyl-terminated layers consisting of long alkyl-chain thiols vs. thioctic acid with short, sterically separated, alkyl groups are compared and contrasted. NEXAFS shows a conformational change, or chemical switchability, with carboxyl groups tilted over and carboxylate endgroups more upright. Surface-attached loops and simple surface-attached rotaxanes are quantitatively characterized, and preparation conditions that lead to desired films are outlined. A dithiol is often insufficient to form a molecular species bound at each end to the substrate, while a structurally related disulfide-containing polymer yields surface-attached loops. Similarly, spectroscopic techniques show the successful production of a simple, surface-attached rotaxane that requires a "molecular riveting" step to hold the mechanically attached crown ether rings in place until disulfides in the molecules adsorb onto the gold. Finally, by introducing an aldehyde into the crown ether portion of this well-characterized surface-attached rotaxane, conformational changes are directly measured when the aldehyde is reacted with aniline. These fundamental results have implications for the creation of nanoscale functional surfaces using molecular monolayers.

  5. Characterization of Functionalized Self-Assembled Monolayers and Surface-Attached Interlocking Molecules Using Near-Edge X-ray Absorption Fine Structure Spectroscopy

    SciTech Connect

    Willey, T; Willey, T

    2004-03-24

    Quantitative knowledge of the fundamental structure and substrate binding, as well as the direct measurement of conformational changes, are essential to the development of self-assembled monolayers (SAMs) and surface-attached interlocking molecules, catenanes and rotaxanes. These monolayers are vital to development of nano-mechanical, molecular electronic, and biological/chemical sensor applications. This dissertation investigates properties of functionalized SAMs in sulfur-gold based adsorbed molecular monolayers using quantitative spectroscopic techniques including near-edge x-ray absorption fine structure spectroscopy (NEXAFS) and x-ray photoelectron spectroscopy (XPS). The stability of the gold-thiolate interface is addressed. A simple model SAM consisting of dodecanethiol adsorbed on Au(111) degrades significantly in less than 24 hours under ambient laboratory air. S 2p and O 1s XPS show the gold-bound thiolates oxidize to sulfinates and sulfonates. A reduction of organic material on the surface and a decrease in order are observed as the layer degrades. The effect of the carboxyl vs. carboxylate functionalization on SAM structure is investigated. Carboxyl-terminated layers consisting of long alkyl-chain thiols vs. thioctic acid with short, sterically separated, alkyl groups are compared and contrasted. NEXAFS shows a conformational change, or chemical switchability, with carboxyl groups tilted over and carboxylate endgroups more upright. Surface-attached loops and simple surface-attached rotaxanes are quantitatively characterized, and preparation conditions that lead to desired films are outlined. A dithiol is often insufficient to form a molecular species bound at each end to the substrate, while a structurally related disulfide-containing polymer yields surface-attached loops. Similarly, spectroscopic techniques show the successful production of a simple, surface-attached rotaxane that requires a ''molecular riveting'' step to hold the mechanically attached crown ether rings in place until disulfides in the molecules adsorb onto the gold. Finally, by introducing an aldehyde into the crown ether portion of this well-characterized surface-attached rotaxane, conformational changes are directly measured when the aldehyde is reacted with aniline. These fundamental results have implications for the creation of nanoscale functional surfaces using molecular monolayers.

  6. Aminophenyl double decker silsesquioxanes: Spectroscopic elucidation, physical and thermal characterization, and their applications

    NASA Astrophysics Data System (ADS)

    Schoen, Beth Whitney

    The incorporation of cage-like silsesquioxanes (SQ) to form polymers has demonstrated property enhancements in areas such as: thermal and mechanical characteristics, flame retardance, dielectric properties, and oxidative resistance. However, with most hybrid polymers investigated, the attached SQs are pendant with respect to the polymer backbone. A recently developed class of these nano-structured, cage-like silsesquioxanes, formally known as double decker silsesquioxanes (DDSQ), offers the opportunity to form hybrid polymers with SQ cages as a part of the polymer backbone. However, during the capping reaction, these functionalized DDSQs generate cis and trans isomers with respect to the 3D Si-O core. Therefore, it is logical to characterize properties, which will allow for optimization of capping reaction parameters, particularly if one isomer is favored over the other. Moreover, these characteristics are also relevant when reacting or incorporating these isomers, or mixtures thereof, with other molecules to form novel materials. In this dissertation, three aminophenyl DDSQs were synthesized. More specifically, two meta- aminophenyl DDSQs, which were differentiated according to the moiety attached to the D-Si (methyl or cyclohexyl), and one para-aminophenyl DDSQ with a methyl moiety were used. Chemical, physical, and thermal characteristics were evaluated for individual isomers as well as binary mixtures of different cis/trans ratios. The 1H NMR spectra of the cis and trans isomers of these DDSQ had not previously been assigned to a degree that allowed for quantification, which was necessary for these studies. Thus, 1H-29Si HMBC correlations were applied to facilitate 1H spectral assignments and also to confirm previous 29Si assignments. Using 1H NMR not only saves time and material over 29Si NMR, but also provides a more accurate quantification, thus allowing for the ratio of cis and trans isomers present in each compound to be determined. Solubility behavior was investigated for the individual isomers, such that separation techniques could be developed. It was found that cis isomers were 33 times more soluble than trans isomers for para-aminophenyl (R = methyl), and 22 times more soluble for the analogous meta-aminophenyl in a solution of THF and hexanes. For a more sterically hindered meta-aminophenyl (R = cyclohexyl), cis isomers were only 3.5 times more soluble, and the overall solubility was also the lowest. Phase diagrams representing solid-liquid melt equilibria of the binary cis/trans mixtures were developed. Single crystal x-ray diffraction data of isolated isomers helped to interpret the phase behavior. Both compounds with a methyl moiety exhibited eutectic phase diagrams. Their trans isomers were higher melting and exhibited larger packing density. Changing from para- to meta-aminophenyl shifted the solid-liquid equilibrium further from ideal, with decreased activity coefficients. Cyclohexyl DDSQ exhibited an isomorphic phase diagram (a complete solid-solution), attributed to cyclohexyl being more similar in size to the phenyl moieties. A specific application that was chosen for these DDSQ was high performance thermosetting oligoimides. They displayed advantages over their organic counterparts in areas such as the liquid to solid transition and viscosity, which improves the processing window. Additionally, they increased the overall degree of cross-linking leading to improved oxidative stability at elevated temperatures.

  7. Fourier transform infrared and Raman spectroscopic characterization of homogeneous solution concentration gradients near a container wall at different temperatures

    NASA Technical Reports Server (NTRS)

    Loo, B. H.; Burns, D. H.; Lee, Y. G. L.; Emerson, M. T.

    1991-01-01

    Fourier transform infrared (FTIR) and Raman spectroscopic techniques were used to study the solution concentration gradient in succino nitrile-rich and water-rich homogeneous solutions. The spectroscopic data shows significant concentration dependency. Although FTIR-attenuated total reflectance could not yield surface spectra since the evanescent infrared wave penetrated deep into the bulk solution, it showed that water-rich clusters were decreased at higher temperatures. This result is consistent with the calorimetric results reported earlier.

  8. Synthesis, spectroscopic characterization and antimicrobial activity of binuclear metal complexes of a new asymmetrical Schiff base ligand: DNA binding affinity of copper(II) complexes.

    PubMed

    Shebl, Magdy

    2014-01-01

    The 1:1 condensation of o-acetoacetylphenol and 1,2-diaminopropane under condition of high dilution gives the mono-condensed Schiff base, (E)-3-(1-aminopropan-2-ylimino)-1-(2-hydroxyphenyl)butan-1-one. The mono-condensed Schiff base has been used for further condensation with isatin to obtain the new asymmetrical dicompartmental Schiff base ligand, (E)-3-(2-((E)-4-(2-hydroxyphenyl)-4-oxobutan-2-ylideneamino) propylimino)indolin-2-one (H3L) with a N2O3 donor set. Reactions of the ligand with metal salts give a series of new binuclear complexes. The ligand and its metal complexes were characterized by elemental analyses, IR, (1)H and (13)C NMR, electronic, ESR and mass spectra, conductivity and magnetic susceptibility measurements as well as thermal analyses. The analytical and spectroscopic tools showed that the complexes can be formulated as: [(HL)(VO)2(SO4)(H2O)]4H2O, [(HL)Fe2Cl4(H2O)3]EtOH, [(HL)Fe2(ox)Cl2(H2O)3]2H2O, [(L)M2(OAc)(H2O)m]nH2O; M=Co, Ni or Cu, m=4, 0 and n=2, 3, [(HL)Cu2Cl]Cl6H2O and [(L)(UO2)2(OAc)(H2O)3]6H2O. The metal complexes exhibited octahedral geometrical arrangements except copper complexes that exhibited tetrahedral geometries and uranyl complex in which the metal ion is octa-coordinated. The Schiff base and its metal complexes were evaluated for antimicrobial activity against Gram positive bacteria (Staphylococcus aureus), Gram negative bacteria (Escherichia coli) and fungi (Candida albicans and Aspergillus flavus). The ligand and some of its complexes were found to be biologically active. The DNA-binding properties of the copper complexes (6 and 7) have been investigated by electronic absorption, fluorescence and viscosity measurements. The results obtained indicate that these complexes bind to DNA via an intercalation binding mode with an intrinsic binding constant, Kb of 1.3410(4) and 2.510(4) M(-1), respectively. PMID:23988527

  9. Synthesis, spectroscopic characterization and antimicrobial activity of binuclear metal complexes of a new asymmetrical Schiff base ligand: DNA binding affinity of copper(II) complexes

    NASA Astrophysics Data System (ADS)

    Shebl, Magdy

    2014-01-01

    The 1:1 condensation of o-acetoacetylphenol and 1,2-diaminopropane under condition of high dilution gives the mono-condensed Schiff base, (E)-3-(1-aminopropan-2-ylimino)-1-(2-hydroxyphenyl)butan-1-one. The mono-condensed Schiff base has been used for further condensation with isatin to obtain the new asymmetrical dicompartmental Schiff base ligand, (E)-3-(2-((E)-4-(2-hydroxyphenyl)-4-oxobutan-2-ylideneamino) propylimino)indolin-2-one (H3L) with a N2O3 donor set. Reactions of the ligand with metal salts give a series of new binuclear complexes. The ligand and its metal complexes were characterized by elemental analyses, IR, 1H and 13C NMR, electronic, ESR and mass spectra, conductivity and magnetic susceptibility measurements as well as thermal analyses. The analytical and spectroscopic tools showed that the complexes can be formulated as: [(HL)(VO)2(SO4)(H2O)]·4H2O, [(HL)Fe2Cl4(H2O)3]·EtOH, [(HL)Fe2(ox)Cl2(H2O)3]·2H2O, [(L)M2(OAc)(H2O)m]·nH2O; M = Co, Ni or Cu, m = 4, 0 and n = 2, 3, [(HL)Cu2Cl]Cl·6H2O and [(L)(UO2)2(OAc)(H2O)3]·6H2O. The metal complexes exhibited octahedral geometrical arrangements except copper complexes that exhibited tetrahedral geometries and uranyl complex in which the metal ion is octa-coordinated. The Schiff base and its metal complexes were evaluated for antimicrobial activity against Gram positive bacteria (Staphylococcus aureus), Gram negative bacteria (Escherichia coli) and fungi (Candida albicans and Aspergillus flavus). The ligand and some of its complexes were found to be biologically active. The DNA-binding properties of the copper complexes (6 and 7) have been investigated by electronic absorption, fluorescence and viscosity measurements. The results obtained indicate that these complexes bind to DNA via an intercalation binding mode with an intrinsic binding constant, Kb of 1.34 × 104 and 2.5 × 104 M-1, respectively.

  10. Structures and spectroscopic characterization of calcium chloride-nicotinamide, -isonicotinamide, -picolinamide and praseodymium bromide-nicotinamide complexes

    NASA Astrophysics Data System (ADS)

    Xue, Junhui; Jiang, Ye; Li, Weihong; Yang, Limin; Xu, Yizhuang; Zhao, Guozhong; Zhang, Gaohui; Bu, Xiaoxia; Liu, Kexin; Chen, Jia'er; Wu, Jinguang

    2015-02-01

    The coordination structures formed by calcium complexes with nicotinamide (na), isonicotinamide (ina) and picolinamide (pa) and praseodymium bromide-na are reported. The structures of CaCl2·(C6H6N2O)2·2H2O (Ca-na), CaCl2·(C6H6N2O)2·4H2O (Ca-ina), CaCl2·(C6H6N2O)2·5H2O (Ca-pa) and PrBr3·(C6H6N2O)2·6H2O (PrBr-na) in the solid state have been characterized by X-ray single crystal diffraction, FTIR, FIR, THz and Raman spectroscopies. Carbonyl oxygen of nicotinamide is coordinated to Ca2+, but it is O-monodentate (carbonyl oxygen) and N,O-bidentate ligand (pyridyl nitrogen and carbonyl oxygen) for Pr3+ to form a chain structure in PrBr-na. For isonicotinamide, only carbonyl oxygen atom is coordinated to Ca2+. Pyridyl nitrogen and carbonyl oxygen of picolinamide are coordinated to Ca2+ to form a five-membered ring structure. The crystal structure and spectroscopic results indicate the differences of the coordination of Ca and Pr ions, the changes of hydrogen bonds and conformation of the ligands induced by complexation. Unlike transition metal ions, Sr2+ or lanthanide ions, Ca2+ is inclined to coordinate to carbonyl oxygen atoms of the ligands.

  11. Description of the Role of Shot Noise in Spectroscopic Absorption and Emission Measurements with Photodiode and Photomultiplier Tube Detectors: Information for an Instrumental Analysis Course

    ERIC Educational Resources Information Center

    McClain, Robert L.; Wright, John C.

    2014-01-01

    A description of shot noise and the role it plays in absorption and emission measurements using photodiode and photomultiplier tube detection systems is presented. This description includes derivations of useful forms of the shot noise equation based on Poisson counting statistics. This approach can deepen student understanding of a fundamental

  12. Description of the Role of Shot Noise in Spectroscopic Absorption and Emission Measurements with Photodiode and Photomultiplier Tube Detectors: Information for an Instrumental Analysis Course

    ERIC Educational Resources Information Center

    McClain, Robert L.; Wright, John C.

    2014-01-01

    A description of shot noise and the role it plays in absorption and emission measurements using photodiode and photomultiplier tube detection systems is presented. This description includes derivations of useful forms of the shot noise equation based on Poisson counting statistics. This approach can deepen student understanding of a fundamental…

  13. Thermophysics Characterization of Multiply Ionized Air Plasma Absorption of Laser Radiation

    NASA Technical Reports Server (NTRS)

    Wang, Ten-See; Rhodes, Robert; Turner, Jim (Technical Monitor)

    2002-01-01

    The impact of multiple ionization of air plasma on the inverse Bremsstrahlung absorption of laser radiation is investigated for air breathing laser propulsion. Thermochemical properties of multiply ionized air plasma species are computed for temperatures up to 200,000 deg K, using hydrogenic approximation of the electronic partition function; And those for neutral air molecules are also updated for temperatures up to 50,000 deg K, using available literature data. Three formulas for absorption are calculated and a general formula is recommended for multiple ionization absorption calculation. The plasma composition required for absorption calculation is obtained by increasing the degree of ionization sequentially, up to quadruple ionization, with a series of thermal equilibrium computations. The calculated second ionization absorption coefficient agrees reasonably well with that of available data. The importance of multiple ionization modeling is demonstrated with the finding that area under the quadruple ionization curve of absorption is found to be twice that of single ionization. The effort of this work is beneficial to the computational plasma aerodynamics modeling of laser lightcraft performance.

  14. Accurate spectroscopic characterization of oxirane: A valuable route to its identification in Titan's atmosphere and the assignment of unidentified infrared bands

    SciTech Connect

    Puzzarini, Cristina; Biczysko, Malgorzata; Bloino, Julien; Barone, Vincenzo

    2014-04-20

    In an effort to provide an accurate spectroscopic characterization of oxirane, state-of-the-art computational methods and approaches have been employed to determine highly accurate fundamental vibrational frequencies and rotational parameters. Available experimental data were used to assess the reliability of our computations, and an accuracy on average of 10 cm{sup 1} for fundamental transitions as well as overtones and combination bands has been pointed out. Moving to rotational spectroscopy, relative discrepancies of 0.1%, 2%-3%, and 3%-4% were observed for rotational, quartic, and sextic centrifugal-distortion constants, respectively. We are therefore confident that the highly accurate spectroscopic data provided herein can be useful for identification of oxirane in Titan's atmosphere and the assignment of unidentified infrared bands. Since oxirane was already observed in the interstellar medium and some astronomical objects are characterized by very high D/H ratios, we also considered the accurate determination of the spectroscopic parameters for the mono-deuterated species, oxirane-d1. For the latter, an empirical scaling procedure allowed us to improve our computed data and to provide predictions for rotational transitions with a relative accuracy of about 0.02% (i.e., an uncertainty of about 40 MHz for a transition lying at 200 GHz).

  15. Accurate Spectroscopic Characterization of Oxirane: A Valuable Route to its Identification in Titan's Atmosphere and the Assignment of Unidentified Infrared Bands

    NASA Astrophysics Data System (ADS)

    Puzzarini, Cristina; Biczysko, Malgorzata; Bloino, Julien; Barone, Vincenzo

    2014-04-01

    In an effort to provide an accurate spectroscopic characterization of oxirane, state-of-the-art computational methods and approaches have been employed to determine highly accurate fundamental vibrational frequencies and rotational parameters. Available experimental data were used to assess the reliability of our computations, and an accuracy on average of 10 cm-1 for fundamental transitions as well as overtones and combination bands has been pointed out. Moving to rotational spectroscopy, relative discrepancies of 0.1%, 2%-3%, and 3%-4% were observed for rotational, quartic, and sextic centrifugal-distortion constants, respectively. We are therefore confident that the highly accurate spectroscopic data provided herein can be useful for identification of oxirane in Titan's atmosphere and the assignment of unidentified infrared bands. Since oxirane was already observed in the interstellar medium and some astronomical objects are characterized by very high D/H ratios, we also considered the accurate determination of the spectroscopic parameters for the mono-deuterated species, oxirane-d1. For the latter, an empirical scaling procedure allowed us to improve our computed data and to provide predictions for rotational transitions with a relative accuracy of about 0.02% (i.e., an uncertainty of about 40 MHz for a transition lying at 200 GHz).

  16. ACCURATE SPECTROSCOPIC CHARACTERIZATION OF OXIRANE: A VALUABLE ROUTE TO ITS IDENTIFICATION IN TITANS ATMOSPHERE AND THE ASSIGNMENT OF UNIDENTIFIED INFRARED BANDS

    PubMed Central

    Puzzarini, Cristina; Biczysko, Malgorzata; Bloino, Julien; Barone, Vincenzo

    2015-01-01

    In an effort to provide an accurate spectroscopic characterization of oxirane, state-of-the-art computational methods and approaches have been employed to determine highly accurate fundamental vibrational frequencies and rotational parameters. Available experimental data were used to assess the reliability of our computations, and an accuracy on average of 10 cm?1 for fundamental transitions as well as overtones and combination bands has been pointed out. Moving to rotational spectroscopy, relative discrepancies of 0.1%, 2%3%, and 3%4% were observed for rotational, quartic, and sextic centrifugal-distortion constants, respectively. We are therefore confident that the highly accurate spectroscopic data provided herein can be useful for identification of oxirane in Titans atmosphere and the assignment of unidentified infrared bands. Since oxirane was already observed in the interstellar medium and some astronomical objects are characterized by very high D/H ratios, we also considered the accurate determination of the spectroscopic parameters for the mono-deuterated species, oxirane-d1. For the latter, an empirical scaling procedure allowed us to improve our computed data and to provide predictions for rotational transitions with a relative accuracy of about 0.02% (i.e., an uncertainty of about 40 MHz for a transition lying at 200 GHz). PMID:26543240

  17. Characterization and Processing of Organic Nonlinear Optical Materials using Ellipsometric, Waveguiding, and Absorption Spectroscopy Techniques

    NASA Astrophysics Data System (ADS)

    Olbricht, Benjamin C.

    The first focus of this work is to describe methods for characterizing organic electro-optic materials. Teng-Man Ellipsometry and Attenuated Total Internal Reflection are reviewed. Experimental techniques for these instruments are described and the calculation of an electro-optic activity is derived. The two techniques are compared; it has been found that in Situ Teng-Man ellipsometry is useful to determine poling conditions but not for reliably evaluating electro-optic activity. Attenuated Total Internal Reflection is found to provide very reliable and precise measurements of electro-optic activity and linear optical constants. As a reference, many materials systems have been evaluated and their electro-optic activities are recorded herein. Methods for fabricating devices for test by Teng-Man ellipsometry and Attenuated Total Internal Reflection are presented. A process for inducing Pockel's response via contact-geometry electric field poling is also described, along with modifications to the simple slab dielectric device to enhance the efficacy of poling. An additional method for enhancing the efficiency of poling is presented. This technique relies on the photoisomerization of azobenzene dyes under 532nm radiation to reduce the dimensionality accessible to chromophores doped into the azobenzene matrix. This effect is known as "Laser Assisted Poling" and is shown to increase poling efficiency by more than two fold. The second purpose of this work is to present an experimental technique to measure the order parameter = 3cos 2q -12 . This method is known as Variable-Angle Polarization-Referenced Absorption Spectroscopy (VAPRAS). The experimental apparatus used for VAPRAS introduces small alterations to a UV/Vis Spectrophotometer and an order parameter is derived by exclusively using classical models for transmittance. VAPRAS provides an effective refractive index for the electro-optic material film which is used to calculate the order of absorbers in the film. The results of the VAPRAS method are compared with rigorous (Jones Matrix) simulations of absorbance and Monte Carlo simulations of poling. Both comparisons conclude that the order is low, ? 0.05, and their agreement with theory is within experimental error. Theoretical simulations of poling are employed to relate the results of VAPRAS to a noncentrosymmetric order parameter . Finally, a solid-state first molecular hyperpolarizability is calculated from these values, measurements of electro-optic activity, linear optical constants and other secondary properties of the electro-optic material.

  18. Isolation, characterization, spectroscopic properties and quantum chemical computations of an important phytoalexin resveratrol as antioxidant component from Vitis labrusca L. and their chemical compositions

    NASA Astrophysics Data System (ADS)

    Güder, Aytaç; Korkmaz, Halil; Gökce, Halil; Alpaslan, Yelda Bingöl; Alpaslan, Gökhan

    2014-12-01

    In this study, isolation and characterization of trans-resveratrol (RES) as an antioxidant compound were carried out from VLE, VLG and VLS. Furthermore, antioxidant activities were evaluated by using six different methods. Finally, total phenolic, flavonoid, ascorbic acid, anthocyanin, lycopene, β-carotene and vitamin E contents were carried out. In addition, the FT-IR, 13C and 1H NMR chemical shifts and UV-vis. spectra of trans-resveratrol were experimentally recorded. Quantum chemical computations such as the molecular geometry, vibrational frequencies, UV-vis. spectroscopic parameters, HOMOs-LUMOs energies, molecular electrostatic potential (MEP), natural bond orbitals (NBO) and nonlinear optics (NLO) properties of title molecule have been calculated by using DFT/B3PW91 method with 6-311++G(d,p) basis set in ground state for the first time. The obtained results show that the calculated spectroscopic data are in a good agreement with experimental data.

  19. Isolation, characterization, spectroscopic properties and quantum chemical computations of an important phytoalexin resveratrol as antioxidant component from Vitis labrusca L. and their chemical compositions.

    PubMed

    Gder, Ayta; Korkmaz, Halil; Gkce, Halil; Alpaslan, Yelda Bingl; Alpaslan, Gkhan

    2014-12-10

    In this study, isolation and characterization of trans-resveratrol (RES) as an antioxidant compound were carried out from VLE, VLG and VLS. Furthermore, antioxidant activities were evaluated by using six different methods. Finally, total phenolic, flavonoid, ascorbic acid, anthocyanin, lycopene, ?-carotene and vitamin E contents were carried out. In addition, the FT-IR, (13)C and (1)H NMR chemical shifts and UV-vis. spectra of trans-resveratrol were experimentally recorded. Quantum chemical computations such as the molecular geometry, vibrational frequencies, UV-vis. spectroscopic parameters, HOMOs-LUMOs energies, molecular electrostatic potential (MEP), natural bond orbitals (NBO) and nonlinear optics (NLO) properties of title molecule have been calculated by using DFT/B3PW91 method with 6-311++G(d,p) basis set in ground state for the first time. The obtained results show that the calculated spectroscopic data are in a good agreement with experimental data. PMID:24967544

  20. Identification and Characterization of Visible Absorption Components in Aqueous Methylglyoxal-Ammonium Sulfate Mixtures

    NASA Astrophysics Data System (ADS)

    McGivern, W. S.; Allison, T. C.; Radney, J. G.; Zangmeister, C. D.

    2014-12-01

    The aqueous reaction of methylglyoxal (MG) with ammonium sulfate has been suggested as a source of atmospheric ``brown carbon.'' We have utilized high-performance liquid chromatography coupled to ultraviolet-visible spectroscopy and tandem mass spectrometry to study the products of this reaction at high concentrations. The overall product spectrum shows a large number of distinct components; however, the visible absorption from this mixture is derived a very small number of components. The largest contributor is an imine-substituted (C=N-H) product of aldol condensation/facile dehydration reaction between the parent MG and a hydrated product of the MG + ammonia reaction. The asymmetric nature of this compound relative to the aldol condensation of two MG results in a sufficiently large redshift of the UV absorption spectrum that absorption of visible radiation can occur in the long-wavelength tail. The simplicity of the imine products is a result of a strong bias toward ketimine products due to the extensive hydration of the aldehydic moiety in the parent in aqueous solution. In addition, a strong pH dependence of the absorption cross section was observed with significantly greater absorption under more basic conditions. We have performed time-dependent density functional theory calculations to evaluate the absorption spectra of all of the possible condensation products and their respective ions, and the results are consistent with the experimental observations. We have also observed smaller concentrations of other condensation products of the imine-substituted parent species that do not contribute significantly to the visible absorption but have not been previously discussed.

  1. X-Ray Absorption And EPR Spectroscopic Studies of the Biotransformations of Chromium(Vi) in Mammalian Cells. Is Chromodulin An Artifact of Isolation Methods?

    SciTech Connect

    Levina, A.; Harris, H.H.; Lay, P.A.; /Sydney U.

    2007-07-10

    Very different biological activities are usually ascribed to Cr(VI) (a toxin and carcinogen) and Cr(III) (an antidiabetic agent), although recent evidence suggests that both these types of actions are likely to arise from cellular uptake of varying concentrations of Cr(VI). The first systematic study of XANES spectra of Cr(III) complexes formed in Cr(VI)-treated mammalian cells (A549, HepG2, V79, and C2C12 cell lines), and in subcellular fractions of A549 cells, has been performed using a library of XANES spectra of model Cr(III) complexes. The results of multiple linear regression analyses of XANES spectra, in combination with multiple-scattering fits of XAFS spectra, indicate that Cr(III) formed in Cr(VI)-treated cells is most likely to bind to carboxylato, amine, and imidazole residues of amino acids, and to a lesser extent to hydroxo or aqua ligands. A combination of XANES and EPR spectroscopic data for Cr(VI)-treated cells indicates that the main component of Cr(III) formed in such cells is bound to high-molecular-mass ligands (>30 kDa, probably proteins), but significant redistribution of Cr(III) occurs during the cell lysis, which leads to the formation of a low-molecular-mass (<30 kDa) Cr(III)-containing fraction. The spectroscopic (XANES, XAFS, and EPR) properties of this fraction were strikingly similar to those of the purported natural Cr(III)-containing factor, chromodulin, that was reported to be isolated from the reaction of Cr(VI) with liver. These data support the hypothesis that a chromodulin-like species, which is formed from such a reaction, is an artifact of the reported isolation procedure.

  2. Local structure and speciation of platinum in fresh and road-aged North American sourced vehicle emissions catalysts: an X-ray absorption spectroscopic study.

    PubMed

    Ash, Peter W; Boyd, David A; Hyde, Timothy I; Keating, Jonathan L; Randlshofer, Gabriele; Rothenbacher, Klaus; Sankar, Gopinathan; Schauer, James J; Shafer, Martin M; Toner, Brandy M

    2014-04-01

    Given emerging concerns about the bioavailability and toxicity of anthropogenic platinum compounds emitted into the environment from sources including vehicle emission catalysts (VEC), the platinum species present in selected North American sourced fresh and road-aged VEC were determined by Pt and Cl X-ray absorption spectroscopy. Detailed analysis of the Extended X-ray Absorption Fine Structure at the Pt L3 and L2 edges of the solid phase catalysts revealed mainly oxidic species in the fresh catalysts and metallic components dominant in the road-aged catalysts. In addition, some bimetallic components (Pt-Ni, Pt-Pd, Pt-Rh) were observed in the road-aged catalysts from supporting Ni-, Pd-, and Rh-K edge XAS studies. These detailed analyses allow for the significant conclusion that this study did not find any evidence for the presence of chloroplatinate species in the investigated solid phase of a Three Way Catalyst or Diesel Oxidation Catalysts. PMID:24568168

  3. Ultra-violet and visible absorption characterization of explosives by differential reflectometry

    NASA Astrophysics Data System (ADS)

    Dubroca, Thierry; Moyant, Kyle; Hummel, Rolf E.

    2013-03-01

    This study presents some optical properties of TNT (2,4,6-trinitrotoluene), RDX, HMX and tetryl, specifically their absorption spectra as a function of concentration in various solvents in the ultraviolet and visible portion of the electromagnetic spectrum. We utilize a standoff explosives detection method, called differential reflectometry (DR). TNT was diluted in six different solvents (acetone, acetonitrile, ethanol, ethyl acetate, methanol, and toluene), which allowed for a direct comparison of absorption features over a wide range of concentrations. A line-shape analysis was adopted with great accuracy (R2 > 0.99) to model the absorption features of TNT in differential reflectivity spectra. We observed a blue shift in the pertinent absorption band with decreasing TNT concentration for all solvents. Moreover, using this technique, it was found that for all utilized solvents the concentration of TNT as well as of RDX, HMX, and tetryl, measured as a function of the transition wavelength of the ultra-violet absorption edge in differential reflectivity spectra shows three distinct regions. A model is presented to explain this behavior which is based on intermolecular hydrogen bonding of explosives molecules with themselves (or lack thereof) at different concentrations. Other intermolecular forces such as dipole-dipole interactions, London dispersion forces and ?-stacking contribute to slight variations in the resulting spectra, which were determined to be rather insignificant in comparison to hydrogen bonding. The results are aimed towards a better understanding of the DR spectra of explosives energetic materials.

  4. Free electron concentration dependent sub-bandgap optical absorption characterization of bulk GaN crystals

    NASA Astrophysics Data System (ADS)

    Pimputkar, S.; Suihkonen, S.; Imade, M.; Mori, Y.; Speck, J. S.; Nakamura, S.

    2015-12-01

    Optical transmission measurements were performed on high quality bulk gallium nitride (GaN) crystals grown by sodium flux, hydride vapor phase epitaxy, and the ammonothermal method with varying free electron concentrations ranging from 4×1016 cm-3 to 9×1018 cm-3. The quality of the crystals was analyzed by x-ray diffraction, threading dislocation density determination, impurity concentrations, and Hall mobility measurements. The sub-bandgap absorption coefficient and index of refraction was determined based on illumination wavelengths ranging from 360 nm to 800 nm. Phonon-assisted free carrier absorption was determined to be the dominant absorption mechanism above approximately 0.1 cm-1. The absorption coefficient at 450 nm varied linearly from 0.1 cm-1 to 5 cm-1 for free electron concentrations ranging from 1×1017 cm-3 to 9×1018 cm-3. The ammonothermal GaN samples exhibited a strong defect related onset of absorption above 2.9 eV which can be explained by the presence of appreciable hydrogenated gallium vacancies having defect states close to the valance band within the electric bandgap of GaN. The presence of hydrogenated gallium vacancies was experimentally confirmed by Fourier transform infrared absorbance measurements and double hydrogenated gallium vacancy defect are speculated to be prominent in ammonothermal GaN.

  5. Ultra-violet and visible absorption characterization of explosives by differential reflectometry.

    PubMed

    Dubroca, Thierry; Moyant, Kyle; Hummel, Rolf E

    2013-03-15

    This study presents some optical properties of TNT (2,4,6-trinitrotoluene), RDX, HMX and tetryl, specifically their absorption spectra as a function of concentration in various solvents in the ultraviolet and visible portion of the electromagnetic spectrum. We utilize a standoff explosives detection method, called differential reflectometry (DR). TNT was diluted in six different solvents (acetone, acetonitrile, ethanol, ethyl acetate, methanol, and toluene), which allowed for a direct comparison of absorption features over a wide range of concentrations. A line-shape analysis was adopted with great accuracy (R(2)>0.99) to model the absorption features of TNT in differential reflectivity spectra. We observed a blue shift in the pertinent absorption band with decreasing TNT concentration for all solvents. Moreover, using this technique, it was found that for all utilized solvents the concentration of TNT as well as of RDX, HMX, and tetryl, measured as a function of the transition wavelength of the ultra-violet absorption edge in differential reflectivity spectra shows three distinct regions. A model is presented to explain this behavior which is based on intermolecular hydrogen bonding of explosives molecules with themselves (or lack thereof) at different concentrations. Other intermolecular forces such as dipole-dipole interactions, London dispersion forces and π-stacking contribute to slight variations in the resulting spectra, which were determined to be rather insignificant in comparison to hydrogen bonding. The results are aimed towards a better understanding of the DR spectra of explosives energetic materials. PMID:23299022

  6. Crystal structure, spectroscopic characterization and density functional studies of (E)-1-((3-methoxyphenylimino)methyl)naphthalen-2-ol.

    PubMed

    Alpaslan, Gökhan; Macit, Mustafa

    2014-01-01

    The Schiff base compound (E)-1-((3-methoxyphenylimino)methyl)naphthalen-2-ol was synthesized from the reaction of 2-hydroxy-1-naphthaldehyde with 3-methoxyaniline. The structural properties of the compound has been characterized by using FT-IR, UV-vis and X-ray single-crystal methods. According to X-ray diffraction result, the title compound exists in the phenol-imine tautomeric form. The molecular geometry, vibrational frequencies of the compound in the ground state have been calculated using the density functional theory (DFT/B3LYP) method with the 6-311++G(d,p) basis set, and compared with the experimental data. The obtained results show that the optimized molecular geometry is well reproduce the crystal structure. The theoretical vibrational frequencies are in good agreement with the experimental values. The calculations of electronic absorption spectra of tautomeric forms of the compound were performed by using TD-DFT calculations both in the gas phase and ethanol solvent. To investigate the tautomeric stability, optimization calculations at the B3LYP/6-311++G(d,p) level were performed for the phenol-imine and keto-amine forms of the compound. According to calculated results, the OH form is more stable than NH form. In addition, molecular electrostatic potential (MEP), frontier molecular orbital analysis (HOMO-LUMO), thermodynamic and, non-linear optical (NLO) properties of the compound were investigated using same theoretical calculations. PMID:24280299

  7. Synthesis, spectroscopic characterization and DFT calculations of N-Methyl-2-(2ʹ-hydroxyphenyl)benzimidazole derivatives

    NASA Astrophysics Data System (ADS)

    Saral, Hasan; Özdamar, Özgür; Uçar, İbrahim; Bekdemir, Yunus; Aygün, Muhittin

    2016-01-01

    1-Methyl-2-(2ʹ-hydroxyphenyl)benzimidazole (1) and 1-Methyl-2-(2ʹ-hydroxy-4ʹ-methylphenyl)benzimidazole (2) compounds have been synthesized and characterized by XRD, IE-MS, FT-IR, UV-Vis and 1H, 13C NMR techniques. The crystal structure of both compounds is stabilized with very strong O-H … N hydrogen-bond and π-π interactions. In the compound 1, an infinite chain structure with a trans-zigzag type was formed along the crystallographic [101] direction. Quantum mechanical calculations of energies, geometries, vibrational wavenumbers, NMR and electronic transitions were carried out by DFT using B3LYP functional combined with 6.31G(d,p) basis set. Calculated bond lengths, bond angles and dihedral angles were only slightly different from the experimental ones. The vibrational study was interpreted by means of potential energy distribution (PED). The electronic absorption spectra of the both compounds were predicted by using the time-dependent DFT methods and good agreement was found between the computational and the experimental values. The chemical shifts (1H and 13C NMR) and isotropic shielding values were calculated by using the gauge-invariant atomic orbital (GIAO) method. The analyses of HOMO and LUMO have been used to explain the charge transfer within the molecule.

  8. Synthesis, characterization and microwave absorption properties of dendrite-like Fe3O4 embedded within amorphous sugar carbon matrix

    NASA Astrophysics Data System (ADS)

    Wu, Hao; Wang, Liuding; Wu, Hongjing

    2014-01-01

    Magnetite dendrites/sugar carbon (MDs/SC) nanocomposites, embedding MDs within amorphous SC matrix, were prepared by simple carbonization-reduction method using ?-Fe2O3 dendrites (HDs) as precursor of MDs and sucrose as SC source, while still maintain the dendritic shape of the precursor. The morphology, composition, structure and static magnetic properties of the as-prepared MDs/SC nanocomposites were characterized by various techniques thoroughly. Particularly, the electromagnetic and microwave absorption properties of the MDs/SC and MDs paraffin composites (40 wt.%) were compared over 2-14 GHz. The results show that the microwave absorption performance of MDs/SC samples is comparable or even superior to that of MDs case. The absorption band with reflection loss (RL) below -20 dB for one of the MDs/SC samples can cover the whole X-band (8-12 GHz) with thickness of 1.8-2.4 mm when the content of MDs in the MDs/SC nanocomposite is 25.8 wt.%, and the minimum RL can reach -49.9 dB at 12.1 GHz when the layer thickness is only 1.9 mm. The excellent microwave absorption properties of the MDs/SC paraffin composites are attributed to the proper match between the complex permittivity and permeability, and the unique fractal structures of MDs.

  9. Mass and NMR spectroscopic characterization of 3,4-methylenedioxypyrovalerone: a designer drug with alpha-pyrrolidinophenone structure.

    PubMed

    Westphal, Folker; Junge, Thomas; Rsner, Peter; Snnichsen, Frank; Schuster, Frank

    2009-09-10

    This study presents and discusses the nuclear magnetic resonance (NMR) spectroscopic and mass spectroscopic data of the designer drug 3,4-methylenedioxypyrovalerone (MDPV), a drug variant of pyrovalerone. MDPV was first seized in Germany in the year 2007. The structure elucidation of the aliphatic part of MDPV was carried out by product ion spectroscopy of the immonium ion with m/z 126 formed after electron ionization, and by 1D (1)H and (13)C NMR spectroscopy. Additional two-dimensional NMR spectroscopy was used to verify the structure of the alkyl side chain, and to determine the methylenedioxy position in the aromatic ring. PMID:19500924

  10. Spectroscopic and thermodynamic characterization of the E151D and E151A altered leucine aminopeptidases from Aeromonas proteolytica.

    PubMed

    Bzymek, Krzysztof P; Swierczek, Sabina I; Bennett, Brian; Holz, Richard C

    2005-11-14

    Previous kinetic characterization of the glutamate 151 (E151)-substituted forms of the leucine aminopeptidase from Aeromonas proteolytica (Vibrio proteolyticus; AAP) has provided critical evidence that this residue functions as the general acid/base. The close proximity of similar glutamate residues to the bridging water/hydroxide of the dinuclear active sites of metalloenzymes (2.80 and 3.94 angstroms in carboxypeptidase G2 and 3.30 and 3.63 angstroms in AAP), suggests it may also be involved in stabilizing the active-site metal ions. Therefore, the structural perturbations of the dinuclear active site of AAP were examined for two E151-substituted forms, namely E151D-AAP and E151A-AAP, by UV-vis and electron paramagnetic resonance (EPR) spectroscopy. UV-vis spectroscopy of Co(II)-substituted E151A-AAP did not reveal any significant changes in the electronic absorption spectra. However UV-vis spectra of mono- and dicobalt(II) E151D-AAP exhibited a lower molecular absorptivity compared to AAP (23 and 43 M(-1) cm(-1) vs. 56 and 109 M(-1) cm(-1) for E151D-AAP and AAP, respectively) suggesting both Co(II) ions reside in distorted octahedral coordination geometry in E151D-AAP. EPR spectra of [Co_(E151D-AAP)], [ZnCo(E151D-AAP)], and [(CoCo(E151D-AAP)] were identical, with g(perpendicular) = 2.35, g(parallel) = 2.19, and E/D = 0.19, similar to [CoCo(AAP)]. On the other hand, the EPR spectrum of [Co_(E151A-AAP)] was best simulated assuming the presence of two species with (i) g(x,y) = 2.509, g(z) = 2.19, E/D = 0.19, A = 0.0069 cm(-1) and (ii) g(x,y) = 2.565, g(z) = 2.19, E/D = 0.20, A = 0.0082 cm(-1) indicative of a five- or six-coordinate species. Isothermal titration calorimetry experiments revealed a large decrease in Zn(II) affinities, with K(d) values elevated by factors of approximately 850 and approximately 24,000 for the first metal binding events of E151D- and E151A-AAP, respectively. The combination of these data indicates that E151 serves to stabilize the dinuclear active site of AAP. PMID:16270998

  11. Effect of characterization of porous metal fiber media on sound absorption coefficient

    NASA Astrophysics Data System (ADS)

    Wang, J. Z.; Ao, Q. B.; Tang, H. P.; Bao, T. F.

    2015-03-01

    Porous metal fiber media (PMFM) is a kind of advanced structural and functional material, and it has attracted a wide spread attention owing to excellent sound absorption performance. The sound absorption property of PMFM is mainly influenced by the fiber diameter, the average pore size and thickness of PMFM. In the paper, three stainless steel fibers with the diameters (?) of 8, 12 and 20 ?m were used to make PMFM with the average pore sizes of 10, 20, 30 and 40 ?m and the thicknesses of 1, 2 and 3 mm by air-laid and sintering processes. The sound absorption coefficients of PMFM were tested in impedance tube using two-microphone transfer-function method according to ISO 10534-2 and ASTM E1050-98 international standards at room temperature. The results show that when the frequency ranges from 50 Hz to 6,400 Hz in material with the average pore size of 20 ?m and the thickness of 3 mm and the fiber diameter of ?8 ?m, the average sound absorption coefficient is the highest.

  12. Synthesis, characterization and femtosecond nonlinear saturable absorption behavior of copper phthalocyanine nanocrystals doped-PMMA polymer thin films

    NASA Astrophysics Data System (ADS)

    Zongo, S.; Dhlamini, M. S.; Neethling, P. H.; Yao, A.; Maaza, M.; Sahraoui, B.

    2015-12-01

    In this work, we report the femtosecond nonlinear saturable absorption response of synthesized copper phthalocyanine nanocrystals (CPc-NCs)-doped PMMA polymer thin films. The samples were initially characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), UV-Vis and scanning electron microscopy (SEM) techniques. The crystalline phase and morphological analysis revealed nanocrystals of monoclinic structure with an average crystallite size between 31.38 nm and 42.5 nm. The femtosecond Z-scan study at 800 nm central wavelength indicated a saturable absorption behavior of which the mechanism is closely related to the surface plasmon resonance (SPR) of the particles. This nonlinear effect could potentially make the CPc-NCs useful in nonlinear optical devices.

  13. Characterizing the Solvated Structure of Photoexcited [Os(terpy)?](2+) with X-ray Transient Absorption Spectroscopy and DFT Calculations.

    PubMed

    Zhang, Xiaoyi; Ppai, Mtys; Mller, Klaus B; Zhang, Jianxin; Canton, Sophie E

    2016-01-01

    Characterizing the geometric and electronic structures of individual photoexcited dye molecules in solution is an important step towards understanding the interfacial properties of photo-active electrodes. The broad family of "red sensitizers" based on osmium(II) polypyridyl compounds often undergoes small photo-induced structural changes which are challenging to characterize. In this work, X-ray transient absorption spectroscopy with picosecond temporal resolution is employed to determine the geometric and electronic structures of the photoexcited triplet state of [Os(terpy)?](2+) (terpy: 2,2':6',2?-terpyridine) solvated in methanol. From the EXAFS analysis, the structural changes can be characterized by a slight overall expansion of the first coordination shell [OsN?]. DFT calculations supports the XTA results. They also provide additional information about the nature of the molecular orbitals that contribute to the optical spectrum (with TD-DFT) and the near-edge region of the X-ray spectra. PMID:26907233

  14. Use of L-edge X-ray absorption spectroscopy to characterize multiple valence states of 3 d transition metals; a new probe for mineralogical and geochemical research

    NASA Astrophysics Data System (ADS)

    Cressey, G.; Henderson, C. M. B.; van der Laan, G.

    1993-07-01

    2 p ( L 2,3) X-ray absorption spectra are presented for a range of minerals to demonstrate the usefulness of L-edge spectroscopy as a symmetry- and valenceselective probe. 2 p XAS provides a sensitive fingerprint of the electronic states of 3 d transition metals and can be applied to phases containing mixtures of such elements. Calculated spectra for 3 d n ? 2 p 5 3 d n+1 transitions provide a basis for the interpretation of the measured spectra. Thus, in principle, multiple valence states of a particular 3 d metal can be precisely characterized from a single L-edge spectrum. Examples of vanadium L-edge spectra are presented for a range of minerals; these complex spectra hold information concerning the presence of vanadium in multiple valence states. The Cu L-edge spectrum of sulvanite (Cu3 VS4) indicates the presence of both Cu+ and Cu2+; the V L-edge spectrum of the same sample shows that both V2+ and V5+ are present. Spectral simulations representing mixtures of Fe d 5 and Fe d 6 states are used to quantify Fe3+/ ?Fe in a spinel, a glass, and an amphibole, all of which contain Fe as a major component. To illustrate the sensitivity of 2 p XAS in a dilute system, the Fe L-edge spectrum of amethyst ( ?-SiO2: Fe) has been recorded; this spectrum shows that 68% of the Fe in amethyst is Fe2+, and 32% is Fe3+. Although previous studies on amethyst using other spectroscopic methods cite evidence for Fe4+, there is no indication in the L-edge spectrum for Fe4+ in amethyst. Comparison of theoretical and experimental spectra not only allows the valence states of 3 d ions to be recognised, but also provides site-symmetry information and crystal field parameters for each ion site.

  15. Nickel complexes of o-amidochalcogenophenolate(2-)/o-iminochalcogenobenzosemiquinonate(1-) pi-radical: synthesis, structures, electron spin resonance, and x-ray absorption spectroscopic evidence.

    PubMed

    Hsieh, Chung-Hung; Hsu, I-Jui; Lee, Chien-Ming; Ke, Shyue-Chu; Wang, Tze-Yuan; Lee, Gene-Hsiang; Wang, Yu; Chen, Jin-Ming; Lee, Jyh-Fu; Liaw, Wen-Feng

    2003-06-16

    The preparation of complexes trans-[Ni(-SeC(6)H(4)-o-NH-)(2)](-) (1), cis-[Ni(-TeC(6)H(4)-o-NH-)(2)](-) (2), trans-[Ni(-SC(6)H(4)-o-NH-)(2)](-) (3), and [Ni(-SC(6)H(4)-o-S-)(2)](-) (4) by oxidative addition of 2-aminophenyl dichalcogenides to anionic [Ni(CO)(SePh)(3)](-) proves to be a successful approach in this direction. The cis arrangement of the two tellurium atoms in complex 2 is attributed to the intramolecular Te.Te contact interaction (Te.Te contact distance of 3.455 A). The UV-vis electronic spectra of complexes 1 and 2 exhibit an intense absorption at 936 and 942 nm, respectively, with extinction coefficient epsilon > 10000 L mol(-)(1) cm(-)(1). The observed small g anisotropy, the principal g values at g(1) = 2.036, g(2) = 2.062, and g(3) = 2.120 for 1 and g(1) = 2.021, g(2) = 2.119, and g(3) = 2.250 for 2, respectively, indicates the ligand radical character accompanied by the contribution of the singly occupied d orbital of Ni(III). The X-ray absorption spectra of all four complexes show L(III) peaks at approximately 854.5 and approximately 853.5 eV. This may indicate a variation of contribution of the Ni(II)-Ni(III) valence state. According to the DFT calculation, the unpaired electron of complex 1 and 2 is mainly distributed on the 3d(xz)() orbital of the nickel ion and on the 4p(z)() orbital of selenium (tellurium, 5p(z)()) as well as the 2p(z)() orbital of nitrogen of the ligand. On the basis of X-ray structural data, UV-vis absorption, electron spin resonance, magnetic properties, DFT computation, and X-ray absorption (K- and L-edge) spectroscopy, the monoanionic trans-[Ni(-SeC(6)H(4)-o-NH-)(2)](-) and cis-[Ni(-TeC(6)H(4)-o-NH-)(2)](-) complexes are appositely described as a resonance hybrid form of Ni(III)-bis(o-amidochalcogenophenolato(2-)) and Ni(II)-(o-amidochalcogenophenolato(2-))-(o-iminochalcogenobenzosemiquinonato(1-) pi-radical; i.e., complexes 1 and 2 contain delocalized oxidation levels of the nickel ion and ligands. PMID:12793831

  16. Chemical and spectroscopic characterizations, ESI-QTOF mass spectrometric measurements and DFT studies of new complexes of palladium(II) with tryptamine and mefenamic acid

    NASA Astrophysics Data System (ADS)

    Carvalho, Marcos A.; Arruda, Eduardo G. R.; Profirio, Daniel M.; Gomes, Alexandre F.; Gozzo, Fábio C.; Formiga, André L. B.; Corbi, Pedro P.

    2015-11-01

    New palladium(II) complexes with tryptamine (Pd-tra) and mefenamic acid (Pd-mef) were prepared and characterized by chemical and spectroscopic methods. Elemental, ESI-QTOF mass spectrometric and thermogravimetric analyses of the compounds confirm the composition [PdCl2(tra)2] for Pd-tra and [Pd(mef)2(bipy)] for Pd-mef. Infrared data indicate the coordination of tryptamine to Pd(II) by the nitrogen atom of the amino group, while for mefenamic acid coordination occurs by the oxygen atom of carboxylate group in a monodentate form. The 1H, 13C and {15N,1H} NMR spectroscopic data confirm the nitrogen coordination of the NH2 group of trypatmine to Pd(II) in the Pd-tra complex and also the oxygen coordination of the carboxylate group of mefenamic acid to Pd(II) in the Pd-mef complex. Density functional theory (DFT) studies were applied to determine the difference in energy between the geometric isomers (cis/trans) of Pd-tra and to optimize the structure of the Pd-mef complex. Raman spectroscopic measurements reinforce the nitrogen coordination of tryptamine to Pd(II) in the Pd-tra complex and confirms the presence of the cis-[PdCl2(tra)2] isomer in the solid state. The complexes are insoluble in water.

  17. Characterization of selenium in UO2 spent nuclear fuel by micro X-ray absorption spectroscopy and its thermodynamic stability.

    PubMed

    Curti, E; Puranen, A; Grolimund, D; Jdernas, D; Sheptyakov, D; Mesbah, A

    2015-10-01

    Direct disposal of spent nuclear fuel (SNF) in deep geological formations is the preferred option for the final storage of nuclear waste in many countries. In order to assess to which extent radionuclides could be released to the environment, it is of great importance to understand how they are chemically bound in the waste matrix. This is particularly important for long-lived radionuclides such as (79)Se, (129)I, (14)C or (36)Cl, which form poorly sorbing anionic species in water and therefore migrate without significant retardation through argillaceous repository materials and host rocks. We present here X-ray absorption spectroscopic data providing evidence that in the investigated SNF samples selenium is directly bound to U atoms as Se(-II) (selenide) ion, probably replacing oxygen in the cubic UO2 lattice. This result is corroborated by a simple thermodynamic analysis, showing that selenide is the stable form of Se under reactor operation conditions. Because selenide is almost insoluble in water, our data indirectly explain the unexpectedly low release of Se in short-term aqueous leaching experiments, compared to iodine or cesium. These results have a direct impact on safety analyses for potential nuclear waste repository sites, as they justify assuming a small fractional release of selenium in performance assessment calculations. PMID:26365814

  18. Structure of the dinuclear active site of urease. X-ray absorption spectroscopic study of native and 2-mercaptoethanol-inhibited bacterial and plant enzymes

    SciTech Connect

    Wang, Shengke; Scott, R.A. ); Lee, M.H.; Hausinger, R.P. ); Clark, P.A.; Wilcox, D.E. )

    1994-04-13

    The structures of the dinuclear Ni(II) active sites of urease from jack bean and Klebsiella aerogenes are compared with and without the addition of the inhibitor 2-mercaptoethanol (2-ME). No significant differences are observed by nickel K-edge X-ray absorption spectroscopy between the plant and bacterial enzymes. The Ni X-ray absorption edge spectra display an 8332-eV 1s[yields]3d peak intensity similar to that observed for five-coordinate Ni(II) compounds[sup 1] for both native and 2-ME-bound derivatives. Curve-fitting of Ni EXAFS data indicates that the average Ni(II) coordination environment in native urease can be described as Ni(imidazole)[sub x](N,O)[sub 5[minus]x], with x = 2 or 3. Addition of 2-ME results in replacement of one of the non-imidazole (N,O) ligands with (S,Cl) (most likely the thiolate sulfur of 2-ME) and results in the appearance of a new peak in the Fourier transforms that can only be fit with a Ni[center dot][center dot][center dot]Ni scattering component at a Ni-Ni distance of [approximately]3.26 [angstrom]. A structure for this 2-ME-bound dinuclear site is proposed to contain the two Ni(II) ions bridged by the thiolate sulfur of 2-ME.

  19. Spectroscopic characterization of iron ores formed in different geological environments using FTIR, XPS, Mössbauer spectroscopy and thermoanalyses

    NASA Astrophysics Data System (ADS)

    Salama, Walid; El Aref, Mourtada; Gaupp, Reinhard

    2015-02-01

    Application of thermoanalyses, FTIR, XPS and Mössbauer spectroscopic methods can differentiate between iron ores formed in different geological environments. Two types of iron ore are formed in shallow marine environments in the Bahariya Depression, Egypt, yellowish brown ooidal ironstones (type 1) and black mud and fossiliferous ironstones (type 2). Both types were subjected to subaerial weathering, producing a dark brown lateritic (pedogenic) iron ore (type 3). Microscopic investigation indicates goethite is the main mineral in types 1 and 3, while hematite is the main mineral in type 2 and also occurs in type 3. Thermoanalyses indicated the dehydroxylation endothermic peak of goethite of type 1 occurs between 329 and 345 °C, while in type 3 occurs between 284 and 330 °C. This variation can be attributed to the nanocrystalline nature of the pedogenic goethite. The presence of an exothermic peak at 754 °C in type 3 is probably attributed to goethite-hematite phase transformation. FTIR spectroscopy indicated that goethite of type 1 is characterized by the presence of the δ-OH band between 799 and 802 cm-1, the γ-OH between 898 and 904 cm-1 and the bulk hydroxyl stretch between 3124 and 3133 cm-1. Goethite of type 3 is characterized by the absence of the bulk hydroxyl stretch band and the δ-OH and γ-OH are shifted to higher Wavenumbers that can attributed to a relative Al-for Fe-substitution. Hematite is identified by two IR bands; the first is between 464 and 475 cm-1 and at the second is between 540 and 557 cm-1. Quartz is identified in all iron ore types, nitrates are identified in types 1 and 2, but absent in type 3 and Kaolinite is identified in type 2. The Mössbauer spectrum of type 1 is fitted with one magnetic sextet corresponding to goethite with an isomer shift (IS) = 0.374 mm s-1, a quadruple splitting (QS) = -0.27 mm s-1 and a hyperfine magnetic field (BHF) = ∼37. The Mössbauer spectrum of type 2 is fitted with one magnetic sextet corresponding to hematite with IS = 0.363 mm s-1, QS = -0.23 mm s-1 and BHF = ∼50. The Mössbauer spectrum of type 3 is best fitted with a single doublet corresponding to ferrihydrite and one sextet corresponding to hematite. The XPS survey scans and the high resolution of the Fe 2p3/2 can differentiate between the yellowish-brown and green ooidal laminae of type 1. The XPS survey scans indicate the presence of Fe, O, C, N, Na, Cl, Ca and Si in all laminae, while S, Zn, Ti and P are only restricted to the green laminae. The high resolution of the Fe 2p3/2 indicates that Fe is linked to OH- ligand in the yellowish-brown laminae that correspond to goethite, while Fe is linked to SO42- ligand in the green laminae. The XPS survey scans of types 2 and 3 indicate that Fe is linked to O2- ligand that corresponds to hematite.

  20. Spectroscopic characterization of iron ores formed in different geological environments using FTIR, XPS, Mssbauer spectroscopy and thermoanalyses.

    PubMed

    Salama, Walid; El Aref, Mourtada; Gaupp, Reinhard

    2014-10-31

    Application of thermoanalyses, FTIR, XPS and Mssbauer spectroscopic methods can differentiate between iron ores formed in different geological environments. Two types of iron ore are formed in shallow marine environments in the Bahariya Depression, Egypt, yellowish brown ooidal ironstones (type 1) and black mud and fossiliferous ironstones (type 2). Both types were subjected to subaerial weathering, producing a dark brown lateritic (pedogenic) iron ore (type 3). Microscopic investigation indicates goethite is the main mineral in types 1 and 3, while hematite is the main mineral in type 2 and also occurs in type 3. Thermoanalyses indicated the dehydroxylation endothermic peak of goethite of type 1 occurs between 329 and 345C, while in type 3 occurs between 284 and 330C. This variation can be attributed to the nanocrystalline nature of the pedogenic goethite. The presence of an exothermic peak at 754C in type 3 is probably attributed to goethite-hematite phase transformation. FTIR spectroscopy indicated that goethite of type 1 is characterized by the presence of the ?-OH band between 799 and 802cm(-1), the ?-OH between 898 and 904cm(-1) and the bulk hydroxyl stretch between 3124 and 3133cm(-1). Goethite of type 3 is characterized by the absence of the bulk hydroxyl stretch band and the ?-OH and ?-OH are shifted to higher Wavenumbers that can attributed to a relative Al-for Fe-substitution. Hematite is identified by two IR bands; the first is between 464 and 475cm(-1) and at the second is between 540 and 557cm(-1). Quartz is identified in all iron ore types, nitrates are identified in types 1 and 2, but absent in type 3 and Kaolinite is identified in type 2. The Mssbauer spectrum of type 1 is fitted with one magnetic sextet corresponding to goethite with an isomer shift (IS)=0.374mms(-1), a quadruple splitting (QS)=-0.27mms(-1) and a hyperfine magnetic field (BHF)=?37. The Mssbauer spectrum of type 2 is fitted with one magnetic sextet corresponding to hematite with IS=0.363mms(-1), QS=-0.23mms(-1) and BHF=?50. The Mssbauer spectrum of type 3 is best fitted with a single doublet corresponding to ferrihydrite and one sextet corresponding to hematite. The XPS survey scans and the high resolution of the Fe 2p3/2 can differentiate between the yellowish-brown and green ooidal laminae of type 1. The XPS survey scans indicate the presence of Fe, O, C, N, Na, Cl, Ca and Si in all laminae, while S, Zn, Ti and P are only restricted to the green laminae. The high resolution of the Fe 2p3/2 indicates that Fe is linked to OH(-) ligand in the yellowish-brown laminae that correspond to goethite, while Fe is linked to SO4(2-) ligand in the green laminae. The XPS survey scans of types 2 and 3 indicate that Fe is linked to O(2-) ligand that corresponds to hematite. PMID:25467675

  1. Biochemical, Kinetic, and Spectroscopic Characterization of Ruegeria pomeroyi DddW--A Mononuclear Iron-Dependent DMSP Lyase.

    PubMed

    Brummett, Adam E; Schnicker, Nicholas J; Crider, Alexander; Todd, Jonathan D; Dey, Mishtu

    2015-01-01

    The osmolyte dimethylsulfoniopropionate (DMSP) is a key nutrient in marine environments and its catabolism by bacteria through enzymes known as DMSP lyases generates dimethylsulfide (DMS), a gas of importance in climate regulation, the sulfur cycle, and signaling to higher organisms. Despite the environmental significance of DMSP lyases, little is known about how they function at the mechanistic level. In this study we biochemically characterize DddW, a DMSP lyase from the model roseobacter Ruegeria pomeroyi DSS-3. DddW is a 16.9 kDa enzyme that contains a C-terminal cupin domain and liberates acrylate, a proton, and DMS from the DMSP substrate. Our studies show that as-purified DddW is a metalloenzyme, like the DddQ and DddP DMSP lyases, but contains an iron cofactor. The metal cofactor is essential for DddW DMSP lyase activity since addition of the metal chelator EDTA abolishes its enzymatic activity, as do substitution mutations of key metal-binding residues in the cupin motif (His81, His83, Glu87, and His121). Measurements of metal binding affinity and catalytic activity indicate that Fe(II) is most likely the preferred catalytic metal ion with a nanomolar binding affinity. Stoichiometry studies suggest DddW requires one Fe(II) per monomer. Electronic absorption and electron paramagnetic resonance (EPR) studies show an interaction between NO and Fe(II)-DddW, with NO binding to the EPR silent Fe(II) site giving rise to an EPR active species (g = 4.29, 3.95, 2.00). The change in the rhombicity of the EPR signal is observed in the presence of DMSP, indicating that substrate binds to the iron site without displacing bound NO. This work provides insight into the mechanism of DMSP cleavage catalyzed by DddW. PMID:25993446

  2. Biochemical, Kinetic, and Spectroscopic Characterization of Ruegeria pomeroyi DddWA Mononuclear Iron-Dependent DMSP Lyase

    PubMed Central

    Brummett, Adam E.; Schnicker, Nicholas J.; Crider, Alexander; Todd, Jonathan D.; Dey, Mishtu

    2015-01-01

    The osmolyte dimethylsulfoniopropionate (DMSP) is a key nutrient in marine environments and its catabolism by bacteria through enzymes known as DMSP lyases generates dimethylsulfide (DMS), a gas of importance in climate regulation, the sulfur cycle, and signaling to higher organisms. Despite the environmental significance of DMSP lyases, little is known about how they function at the mechanistic level. In this study we biochemically characterize DddW, a DMSP lyase from the model roseobacter Ruegeria pomeroyi DSS-3. DddW is a 16.9 kDa enzyme that contains a C-terminal cupin domain and liberates acrylate, a proton, and DMS from the DMSP substrate. Our studies show that as-purified DddW is a metalloenzyme, like the DddQ and DddP DMSP lyases, but contains an iron cofactor. The metal cofactor is essential for DddW DMSP lyase activity since addition of the metal chelator EDTA abolishes its enzymatic activity, as do substitution mutations of key metal-binding residues in the cupin motif (His81, His83, Glu87, and His121). Measurements of metal binding affinity and catalytic activity indicate that Fe(II) is most likely the preferred catalytic metal ion with a nanomolar binding affinity. Stoichiometry studies suggest DddW requires one Fe(II) per monomer. Electronic absorption and electron paramagnetic resonance (EPR) studies show an interaction between NO and Fe(II)-DddW, with NO binding to the EPR silent Fe(II) site giving rise to an EPR active species (g = 4.29, 3.95, 2.00). The change in the rhombicity of the EPR signal is observed in the presence of DMSP, indicating that substrate binds to the iron site without displacing bound NO. This work provides insight into the mechanism of DMSP cleavage catalyzed by DddW. PMID:25993446

  3. A multi-epoch spectroscopic study of the BAL quasar APM 08279+5255. II. Emission- and absorption-line variability time lags

    NASA Astrophysics Data System (ADS)

    Saturni, F. G.; Trevese, D.; Vagnetti, F.; Perna, M.; Dadina, M.

    2016-03-01

    Context. The study of high-redshift bright quasars is crucial to gather information about the history of galaxy assembly and evolution. Variability analyses can provide useful data on the physics of quasar processes and their relation with the host galaxy. Aims: In this study, we aim to measure the black hole mass of the bright lensed BAL QSO APM 08279+5255 at z = 3.911 through reverberation mapping, and to update and extend the monitoring of its C IV absorption line variability. Methods: We perform the first reverberation mapping of the Si IV and C IV emission lines for a high-luminosity quasar at high redshift with the use of 138 R-band photometric data and 30 spectra available over 16 years of observations. We also cross-correlate the C IV absorption equivalent width variations with the continuum light curve to estimate the recombination time lags of the various absorbers and infer the physical conditions of the ionised gas. Results: We find a reverberation-mapping time lag of ~900 rest-frame days for both Si IV and C IV emission lines. This is consistent with an extension of the BLR size-to-luminosity relation for active galactic nuclei up to a luminosity of ~1048 erg s-1, and implies a black hole mass of 1010 M⊙. Additionally, we measure a recombination time lag of ~160 days in the rest frame for the C IV narrow absorption system, which implies an electron density of the absorbing gas of ~2.5 × 104 cm-3. Conclusions: The measured black hole mass of APM 08279+5255 indicates that the quasar resides in an under-massive host-galaxy bulge with Mbulge ~ 7.5MBH, and that the lens magnification is lower than ~8. Finally, the inferred electron density of the narrow-line absorber implies a distance of the order of 10 kpc of the absorbing gas from the quasar, placing it within the host galaxy.

  4. Linear and nonlinear optical absorption characterization of natural laccaic acid dye

    NASA Astrophysics Data System (ADS)

    Zongo, S.; Dhlamini, M. S.; Kerasidou, A. P.; Beukes, P.; Sahraoui, B.; Maaza, M.

    2015-09-01

    We report on the optical performances of laccaic acid dye in solution at different concentrations and dye-poly(methyl methacrylate) composite thin films. The linear spectral characteristics including optical constants, i.e. refractive index ( n) and extinction coefficient ( k), were carried out in a comprehensive way through absorbance, fluorescence and ellipsometric studies. The nonlinear optical parameters such as nonlinear absorption coefficient ? eff (or ? 2), the imaginary third-order susceptibility (Im[ ? (3)]) and the imaginary part of second-order hyperpolarizability ( ?) of the samples were evaluated using the open-aperture Z-scan technique with a laser pulse duration of 10 ns at 532 nm wavelength. The corresponding numerical values of these parameters were of 10-10, 10-11 and 10-32 order, respectively. Two-photon absorption was revealed to be the main driving physical mechanism in the nonlinear response. This suggests that laccaic acid dye can be a potential candidate for NLO materials application.

  5. Fabrication process and electromagnetic wave absorption characterization of a CNT/Ni/epoxy nanocomposite.

    PubMed

    Ryu, Seongwoo; Mo, Chan Bin; Lee, Haeshin; Hong, Soon Hyung

    2013-11-01

    Since carbon nanotube (CNT) was first discovered in 1991, it has been considered as a viable type of conductive filler for electromagnetic wave absorption materials in the GHz range. In this paper, pearl-necklace-structure CNT/Ni nano-powders were fabricated by a polyol process as conductive fillers. Compared to synthesized CNT, pearl-necklace Ni-decorated CNT increased the electrical conductivity by an order of 1 due to the enhancement of the Ni-conductive network. Moreover, the decorated Ni particles prevented the agglomeration of CNTs by counterbalancing the Van der Walls interaction between the CNTs. A CNT/Ni nanocomposite showed a homogeneous dispersion in an epoxy-based matrix. This enhanced physical morphology and electrical properties lead to an increase in the loss tangent and reflection loss in the CNT/Ni/Epoxy nanocomposite compared to these characteristics of a CNT/Epoxy nanocomposite in range of 8-12 GHz. The electromagnetic wave absorption properties of CNT/Ni/epoxy nanocomposites will provide enormous opportunities for electronic applications where lightweight EMI shielding or electro-magnetic wave absorption properties are necessary. PMID:24245312

  6. X-ray absorption spectroscopic studies of the dinuclear iron center in methane monooxygenase and the sulfure and chlorine centers in photographic materials

    SciTech Connect

    DeWitt, J.G.

    1992-12-01

    The dinuclear iron center of the hydroxylase component of soluble methane monooxygenase (MMO) from Methylococcus capsulatus and Methylosinus trichosporiwn has been studied by X-ray absorption spectroscopy. Analysis of the Fe K-edge EXAFS revealed that the first shell coordination of the Fe(HI)Fe(IH) oxidized state of the hydroxylase from M. capsulatus consists of approximately 6 N and 0 atoms at an average distance of 2.04 [Angstrom]. The Fe-Fe distance was determined to be 3.4 [Angstrom]. No evidence for the presence of a short oxo bridge in the iron center of the oxidized hydroxylase was found, suggesting that the active site of MMO is significantly different from the active sites of the dinuclear iron proteins hemery and ribonucleotide reductase. In addition, the results of the first shell fits suggest that there are more oxygen than nitrogen donor ligands.

  7. X-ray absorption spectroscopic studies of the dinuclear iron center in methane monooxygenase and the sulfure and chlorine centers in photographic materials

    SciTech Connect

    DeWitt, J.G.

    1992-12-01

    The dinuclear iron center of the hydroxylase component of soluble methane monooxygenase (MMO) from Methylococcus capsulatus and Methylosinus trichosporiwn has been studied by X-ray absorption spectroscopy. Analysis of the Fe K-edge EXAFS revealed that the first shell coordination of the Fe(HI)Fe(IH) oxidized state of the hydroxylase from M. capsulatus consists of approximately 6 N and 0 atoms at an average distance of 2.04 {Angstrom}. The Fe-Fe distance was determined to be 3.4 {Angstrom}. No evidence for the presence of a short oxo bridge in the iron center of the oxidized hydroxylase was found, suggesting that the active site of MMO is significantly different from the active sites of the dinuclear iron proteins hemery and ribonucleotide reductase. In addition, the results of the first shell fits suggest that there are more oxygen than nitrogen donor ligands.

  8. In situ X-ray Absorption Spectroscopic Investigation of the Electrochemical Conversion Reactions of CuF2-MoO3 Nanocomposite

    SciTech Connect

    A Mansour; F Badway; W Yoon; K Chung; G Amatucci

    2011-12-31

    We have used X-ray absorption spectroscopy at the Cu K-edge to investigate the electrochemical conversion reaction of 20 nm size 85 wt% CuF{sub 2}-15 wt% MoO{sub 3} nanocomposite under in situ conditions. The nanocomposite was prepared by high energy milling. Upon discharge, the lithiation reaction with the nanocomposite resulted in the formation of nanophase metallic Cu, which is consistent with the conversion of CuF{sub 2} into Cu and LiF. Based on XANES and Fourier transforms of EXAFS spectra, we show that the discharge process proceeded via the formation of highly dispersed Cu particles. Based on the coordination number of the first shell of Cu, the average size of the Cu particles was estimated to be in the 1-3 nm range in the fully discharged state.

  9. Mass, NMR and IR spectroscopic characterization of pentedrone and pentylone and identification of their isocathinone by-products.

    PubMed

    Westphal, Folker; Junge, Thomas; Girreser, Ulrich; Greibl, Wolfgang; Doering, Carmen

    2012-04-10

    This study presents and discusses the mass spectrometric, nuclear magnetic resonance spectroscopic and infrared spectroscopic data of the designer drugs pentedrone (2-methylamino-1-phenylpentan-1-one) and its methylenedioxy analog pentylone (2-methylamino-1-(3,4-methylenedioxyphenyl)pentan-1-one). The structure elucidation of the aliphatic parts was carried out by product ion spectroscopy of the immonium ion with m/z=86 formed after electron ionization, and by one- and two-dimensional (1)H- and (13)C-NMR spectroscopy on the hydrochloride salts to verify the structure of the alkyl side chain and to determine the methylenedioxy position in the aromatic ring of pentylone. Furthermore, two typical cathinone synthesis by-products were detected besides the main compounds. Their mass spectra are discussed and for one of them (1-methylamino-1-phenylpentan-2-one (isopentedrone)) a NMR assignment was possible in the existing mixture. PMID:22115724

  10. Aqueous Cadmium Chalcogenide Quantum Dots: Synthesis, Characterization, Spectroscopic Investigation of Electron Transfer Properties and Photovoltaic Device Performance

    NASA Astrophysics Data System (ADS)

    Coughlin, Kathleen M.

    The research presented in this thesis will focus on (1) synthesis and characterization of aqueous CdSe quantum dots (QDs) as alternatives to organic QDs; (2) the roles that linkers and capping groups play on the physical and optical properties of aqueous QDs; (3) performance of QD-sensitized solar cells (QDSSC) incorporating magic-sized clusters (MSCs) vs regular QDs (RQDs) and as a function of the molecular linkers between QDs and TiO2; and (4) the effect of the polysulfide electrolyte on QD-functionalized TiO 2 films and their performance in QDSSCs. The use of QDs as light harvesters has grown over the last few decades due to their unique properties. Water-dispersible QDs are of increasing interest because their syntheses are straightforward, environmentally-benign and more cost-effective. CdSe and CdS QDs were synthesized at room temperature under ambient conditions, by combining a Cd precursor and either Na2SeSO3 (for CdSe) or Na2S2O3 (for CdS), in basic aqueous reaction mixtures. Three different ligands were utilized as capping groups (cysteinate (Cys), mercaptopropionate (MP), and mercaptosuccinate (MS)). Changing the capping-agent, the reagent concentrations and the temperature changed the photophysical properties of the QDs. When Cys was used as the capping-agent, MSCs were formed. When high concentrations of Cys were used or when the reaction mixture was heated, RQDs were formed. When MP and MS were used in the synthesis of CdSe, RQDs were formed. In the synthesis of CdS, MS caused the formation of RQDs, and MP caused formation of a mixture of RQDs and MSCs. Transient absorption spectroscopy and photoelectrochemical experiments were performed to understand the influence of capping-agent and electronic properties (MSCs vs. RQDs) on the efficiency of electron transfer from photoexcited QDs to TiO2. The Cys-CdSe-functionalized TiO2 exhibited more efficient electron injection and/or slower recombination, leading to improved efficiency of QDSSCs. Devices made with Cys-CdSe RQDs exhibited higher efficiencies than QDSSCs with Cys-CdSe MSCs, indicating that the presence of Cys induces greater efficiency in QDSSCs. For QDSSCs, a polysulfide electrolyte is commonly used instead of I-/I3-. Effects of the polysulfide electrolyte and Na2S on CdSe-functionalized TiO2 films were explored to elucidate the chemistry that occurs when CdSe is exposed to the electrolyte in the QDSSCs. Photophysical changes to the CdSe-functionalized films occurred when exposed to the polysulfide electrolyte. Upon immersion of CdSe-functionalized TiO2 films into solutions of Na2S, an initial red shift in the absorption spectrum was observed, followed by a decrease and blue shift of the band. Based on XPS analysis of the films, it was determined that the S within the electrolyte (1) replaced Se or (2) bound to the CdSe-functionalized film without replacing Se. Photoelectrochemical measurements were acquired to analyze device performance with varying [S] within the electrolyte. Upon increase of S, the efficiency of the device increased and gave rise to a better fill factor in the photocurrent-photovoltage data collected.

  11. Constraining the N2O5 UV absorption cross section from spectroscopic trace gas measurements in the tropical mid-stratosphere

    NASA Astrophysics Data System (ADS)

    Kritten, L.; Butz, A.; Chipperfield, M. P.; Dorf, M.; Dhomse, S.; Hossaini, R.; Oelhaf, H.; Prados-Roman, C.; Wetzel, G.; Pfeilsticker, K.

    2014-09-01

    The absorption cross section of N2O5, ?N2O5(?, T), which is known from laboratory measurements with the uncertainty of a factor of 2 (Table 4-2 in (Jet Propulsion Laboratory) JPL-2011; the spread in laboratory data, however, points to an uncertainty in the range of 25 to 30%, Sander et al., 2011), was investigated by balloon-borne observations of the relevant trace gases in the tropical mid-stratosphere. The method relies on the observation of the diurnal variation of NO2 by limb scanning DOAS (differential optical absorption spectroscopy) measurements (Weidner et al., 2005; Kritten et al., 2010), supported by detailed photochemical modelling of NOy (NOx(= NO + NO2) + NO3 + 2N2O5 + ClONO2 + HO2NO2 + BrONO2 + HNO3) photochemistry and a non-linear least square fitting of the model result to the NO2 observations. Simulations are initialised with O3 measured by direct sun observations, the NOy partitioning from MIPAS-B (Michelson Interferometer for Passive Atmospheric Sounding - Balloon-borne version) observations in similar air masses at night-time, and all other relevant species from simulations of the SLIMCAT (Single Layer Isentropic Model of Chemistry And Transport) chemical transport model (CTM). Best agreement between the simulated and observed diurnal increase of NO2 is found if the ?N2O5(?, T) is scaled by a factor of 1.6 0.8 in the UV-C (200-260 nm) and by a factor of 0.9 0.26 in the UV-B/A (260-350 nm), compared to current recommendations. As a consequence, at 30 km altitude, the N2O5 lifetime against photolysis becomes a factor of 0.77 shorter at solar zenith angle (SZA) of 30 than using the recommended ?N2O5(?, T), and stays more or less constant at SZAs of 60. Our scaled N2O5 photolysis frequency slightly reduces the lifetime (0.2-0.6%) of ozone in the tropical mid- and upper stratosphere, but not to an extent to be important for global ozone.

  12. An X-ray absorption spectroscopic study of the metal site preference in Al{sub 1-x}Ga{sub x}FeO{sub 3}

    SciTech Connect

    Walker, James D.S.; Grosvenor, Andrew P.

    2013-01-15

    Magnetoelectric materials have potential for being introduced into next generation technologies, especially memory devices. The AFeO{sub 3} (Pna2{sub 1}; A=Al, Ga) system has received attention to better understand the origins of magnetoelectric coupling. The magnetoelectric properties this system exhibits depend on the amount of anti-site disorder present, which is affected by the composition and the method of synthesis. In this study, Al{sub 1-x}Ga{sub x}FeO{sub 3} was synthesized by the ceramic method and studied by X-ray absorption spectroscopy. Al L{sub 2,3}-, Ga K-, and Fe K-edge spectra were collected to examine how the average metal coordination number changes with composition. Examination of XANES spectra from Al{sub 1-x}Ga{sub x}FeO{sub 3} indicate that with increasing Ga content, Al increasingly occupies octahedral sites while Ga displays a preference for occupying the tetrahedral site. The Fe K-edge spectra indicate that more Fe is present in the tetrahedral site in AlFeO{sub 3} than in GaFeO{sub 3}, implying more anti-site disorder is present in AlFeO{sub 3}. - Graphical abstract: Al{sub 1-x}Ga{sub x}FeO{sub 3} has been investigated by XANES. Through examination of Al L{sub 2,3}-, Ga K-, and Fe K-edge XANES spectra, it was found that more anti-site disorder of the Fe atoms is present in AlFeO{sub 3} compared to in GaFeO{sub 3}. Highlights: Black-Right-Pointing-Pointer Al{sub 1-x}Ga{sub x}FeO{sub 3} was investigated by X-ray absorption spectroscopy. Black-Right-Pointing-Pointer Ga prefers to occupy the tetrahedral site in Al{sub 1-x}Ga{sub x}FeO{sub 3}. Black-Right-Pointing-Pointer Fe prefers to occupy the octahedral sites in Al{sub 1-x}Ga{sub x}FeO{sub 3} as x increases. Black-Right-Pointing-Pointer More anti-site disorder is present in AlFeO{sub 3} compared to in GaFeO{sub 3.}.

  13. Photodynamic properties of toluidine blue characterized by fluorescence and absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Caete, Magdalena; Villanueva, Angeles

    Red light photolysis studies of the production of singlet oxygen by toluidine blue dye photosensitization were measured by the photo-oxidation rate of tryptophan. Absorption spectra of toluidine blue together with each of the four synthetic nucleosides of DNA have been obtained. After irradiation, only deoxyguanosine showed any noticeable reaction at neutral pH. Abreviations (see Fig. 1): TB, toluidine blue; 1O 2, singlet oxygen; TRP, tryptophan; dA, 2'-deoxyadenosine; dC, 2'-deoxycytidine; dT, 2'-deoxythymidine; dG, 2'-deoxyguanosine; NaN 3, sodium azide.

  14. Preformulation characterization and in vivo absorption in beagle dogs of JFD, a novel anti-obesity drug for oral delivery.

    PubMed

    Fan, Yunzhou; Yang, Meiyan; Wang, Yuli; Li, Yanyou; Zhou, Yuanda; Chen, Xiaoping; Shan, Li; Wei, Jun; Gao, Chunsheng

    2015-05-01

    JFD (N-isoleucyl-4-methyl-1,1-cyclopropyl-1-(4-chlorine)phenyl-2-amylamineHCl) is a novel investigational anti-obesity drug without obvious cardiotoxicity. The objective of this study was to characterize the key physicochemical properties of JFD, including solution-state characterization (ionization constant, partition coefficient, aqueous and pH-solubility profile), solid-state characterization (particle size, thermal analysis, crystallinity and hygroscopicity) and drug-excipient chemical compatibility. A supporting in vivo absorption study was also carried out in beagle dogs. JFD bulk powders are prismatic crystals with a low degree of crystallinity, particle sizes of which are within 2-10??m. JFD is highly hygroscopic, easily deliquesces to an amorphous glass solid and changes subsequently to another crystal form under an elevated moisture/temperature condition. Similar physical instability was also observed in real-time CheqSol solubility assay. pK(a) (7.49??0.01), log?P (5.10??0.02) and intrinsic solubility (S0) (1.75??g/ml) at 37?C of JFD were obtained using potentiometric titration method. Based on these solution-state properties, JFD was estimated to be classified as BCS II, thus its dissolution rate may be an absorption-limiting step. Moreover, JFD was more chemically compatible with dibasic calcium phosphate, mannitol, hypromellose and colloidal silicon dioxide than with lactose and magnesium stearate. Further, JFD exhibited an acceptable pharmacokinetic profiling in beagle dogs and the pharmacokinetic parameters T(max), C(max), AUC(0-t) and absolute bioavailability were 1.60??0.81?h, 0.78??0.47??g/ml, 3.77??1.85??gh/ml and 52.30??19.39%, respectively. The preformulation characterization provides valuable information for further development of oral administration of JFD. PMID:24694186

  15. X-ray Absorption Spectroscopic Investigatin of Partially Reduced Cobalt Species in Co-MCM-41 Catalysts During Synthesis of Single-Wall Carbon Nanotubes

    SciTech Connect

    Ciuparu,D.; Haider, P.; Fernandez-Garcia, M.; Chen, Y.; Lim, S.; Haller, G.; Pfefferle, L.

    2005-01-01

    Chemometric tools were employed to analyze the in-situ dynamic X-ray absorption spectroscopy data to probe the state of Co-MCM-41 catalysts during reduction in pure hydrogen and under single-wall carbon nanotube synthesis reaction conditions. The use of the progressive correlation analysis established the sequence in which changes in the spectral features near the Co K edge occurred, and the evolving factor analysis provided evidence for the formation of an intermediate Co{sup 1+} ionic species during reduction of the Co-MCM-41 catalyst in pure hydrogen up to 720 C. This intermediate species preserves the tetrahedral environment in the silica framework and is resistant to complete reduction to the metal in H{sub 2}. While the Co{sup 2+} species is resistant to reduction in pure CO, the intermediate Co{sup 1+} species is more reactive in CO most likely forming cobalt carbonyl-like compounds with high mobility in the MCM-41. These mobile species are the precursors of the metallic clusters growing carbon nanotubes. Controlling the rates of each step of this two-stage reduction process is key to controlling the size of the metallic Co clusters formed in Co-MCM-41 catalysts.

  16. Spectroscopic verification of zinc absorption and distribution in the desert plant Prosopis juliflora-velutina (velvet mesquite) treated with ZnO nanoparticles

    PubMed Central

    Hernandez-Viezcas, J.A.; Castillo-Michel, H.; Servin, A.D.; Peralta-Videa, J.R.; Gardea-Torresdey, J.L.

    2012-01-01

    The impact of metal nanoparticles (NPs) on biological systems, especially plants, is still not well understood. The aim of this research was to determine the effects of zinc oxide (ZnO) NPs in velvet mesquite (Prosopis juliflora-velutina). Mesquite seedlings were grown for 15 days in hydroponics with ZnO NPs (10 nm) at concentrations varying from 500 to 4000 mg L?1. Zinc concentrations in roots, stems and leaves were determined by inductively coupled plasma optical emission spectroscopy (ICP-OES). Plant stress was examined by the specific activity of catalase (CAT) and ascorbate peroxidase (APOX); while the biotransformation of ZnO NPs and Zn distribution in tissues was determined by X-ray absorption spectroscopy (XAS) and micro X-ray fluorescence (?XRF), respectively. ICP-OES results showed that Zn concentrations in tissues (2102 87, 1135 56, and 628 130 mg kg?1 d wt in roots, stems, and leaves, respectively) were found at 2000 mg ZnO NPs L?1. Stress tests showed that ZnO NPs increased CAT in roots, stems, and leaves, while APOX increased only in stems and leaves. XANES spectra demonstrated that ZnO NPs were not present in mesquite tissues, while Zn was found as Zn(II), resembling the spectra of Zn(NO3)2. The ?XRF analysis confirmed the presence of Zn in the vascular system of roots and leaves in ZnO NP treated plants. PMID:22820414

  17. Time-resolved characterization of a filamentary argon discharge at atmospheric pressure in a capillary using emission and absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Schrter, Sandra; Pothiraja, Ramasamy; Awakowicz, Peter; Bibinov, Nikita; Bke, Marc; Niermann, Benedikt; Winter, Jrg

    2013-11-01

    An argon/nitrogen (0.999/0.001) filamentary pulsed discharge operated at atmospheric pressure in a quartz tube is characterized using voltage-current measurements, microphotography, optical emission spectroscopy (OES) and absorption spectroscopy. Nitrogen is applied as a sensor gas for the purpose of OES diagnostic. The density of argon metastable atoms Ar(3P2) is determined using tunable diode laser absorption spectroscopy (TDLAS). Using a plasma chemical model the measured OES data are applied for the characterization of the plasma conditions. Between intense positive pulses the discharge current oscillates with a damped amplitude. It is established that an electric current flows in this discharge not only through a thin plasma filament that is observed in the discharge image but also through the whole cross section of the quartz tube. A diffuse plasma fills the quartz tube during a time between intense current pulses. Ionization waves are propagating in this plasma between the spike and the grounded area of the tube producing thin plasma channels. The diameter of these channels increases during the pause between the propagation of ionization waves probably because of thermal expansion and diffusion. Inside the channels electron densities of 2 1013 cm-3, argon metastable densities 1014 cm-3 and a reduced electric field about 10 Td are determined.

  18. Molecular characterization of copper in soils using X-ray absorption spectroscopy.

    PubMed

    Strawn, Daniel G; Baker, Leslie L

    2009-10-01

    Bioavailability of Cu in the soil is a function of its speciation. In this paper we investigated Cu speciation in six soils using X-ray absorption near edge structure (XANES), extended X-ray absorption fine structure (EXAFS), and synchrotron-based micro X-ray fluorescence (mu-XRF). The XANES and EXAFS spectra in all of the soils were the same. mu-XRF results indicated that the majority of the Cu particles in the soils were not associated with calcium carbonates, Fe oxides, or Cu sulfates. Principal component analysis and target transform of the XANES and EXAFS spectra suggested that Cu adsorbed on humic acid (HA) was an acceptable match. Thus it appears that Cu in all of the soils is primarily associated with soil organic matter (SOM). Theoretical fitting of the molecular structure in the soil EXAFS spectra revealed that the Cu in the soils existed as Cu atoms bound in a bidentate complex to O or N functional groups. PMID:19446385

  19. Facile preparation and characterization of modified magnetic silica nanocomposite particles for oil absorption

    NASA Astrophysics Data System (ADS)

    Yu, Liuhua; Hao, Gazi; Liang, Qianqian; Zhou, Shuai; Zhang, Ning; Jiang, Wei

    2015-12-01

    In this study, a novel environmental-friendly and superhydrophobic oil absorbent was fabricated by modifying magnetic silica nanocomposites. It was demonstrated that the modified rough magnetic silica nanocomposite particles possessed a number of superior features such as superhydrophobicity, superoleophilicity, and high oil-water separation efficiency etc. Moreover, the as-obtained material could be used as excellent absorbents for high density oils such as toluene and many organic liquids including viscous oils e.g. lubricating oil. The lubricating oil intake capacity for the nanocomposites was 7.15 times of its own weight. Importantly, the oil-absorption process of the nanocomposites was selective, fast and efficient when they were used in the purification of oil-contaminated water. Notably, the oil-absorbed nanocomposites could be renewed after suitable absolute ethanol washing and natural drying. In addition, the renewed nanocomposites still remained high oil-absorption capacity after the 20th cycle. These inspiring results show that the oil-absorbent material has good prospects for selection removal of oils and organic solvents on water surface. It is believed that the present work may have provided a novel and facile way for preparing environmental-friendly materials with ideal properties.

  20. Large-scale synthesis, characterization and microwave absorption properties of carbon nanotubes of different helicities

    SciTech Connect

    Qi Xiaosi; Yang Yi; Zhong Wei; Deng Yu; Au Chaktong; Du Youwei

    2009-10-15

    Carbon nanotubes of high helicity (H-HCNTs, Sample A) have been synthesized in large-scale by pyrolysis of acetylene at 450 deg. C over Fe nanoparticles derived from coprecipitation/hydrogen reduction method. With controlled introduction of hydrogen during acetylene pyrolysis, CNTs of low helicity (L-HCNTs, Sample B) and worm-like CNTs (Sample C) were obtained in large quantities. The yields of the CNTs products are high, especially that of H-HCNTs (ca. 7474%). The complex permittivity and permeability of Composites A, B, and C that contain Samples A, B and C (30 wt%) were measured in the 2-18 GHz frequency range. Good absorption of electromagnetic wave (reflection loss<-20 dB) was observed in the 7.18-10.68 and 7.5-10.7 GHz range over Composites B and C (2.0-3.0 mm thickness), respectively. Thus, through the suggested route, CNTs can be produced easily and selectively in large quantities. The lightweight materials can be utilized for microwave absorption. - Graphical abstract: FESEM image of Sample B and reflection loss versus frequency of Composite B (containing 30 wt% of Sample B) in the range of 2-18 GHz.

  1. Synthesis, Characterization, and Microwave Absorption Properties of Reduced Graphene Oxide/Strontium Ferrite/Polyaniline Nanocomposites.

    PubMed

    Luo, Juhua; Shen, Pan; Yao, Wei; Jiang, Cuifeng; Xu, Jianguang

    2016-12-01

    Strontium ferrite nanoparticles were prepared by a coprecipitation method, and reduced graphene oxide/strontium ferrite/polyaniline (R-GO/SF/PANI) ternary nanocomposites were prepared by in situ polymerization method. The morphology, structure, and magnetic properties of the ternary nanocomposites were investigated by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), TEM, Raman, and VSM. The microwave-absorbing properties of the composites were measured by a vector network analyzer. The XRD patterns show the single phase of strontium hexaferrite without other intermediate phases. TEM photographs reveal that strontium ferrite nanoparticles are uniformly dispersed on the surfaces of R-GO sheets. The R-GO/SF/PANI nanocomposite exhibited the best absorption property with the optimum matching thickness of 1.5 mm in the frequency of 2-18 GHz. The value of the maximum RL was -45.00 dB at 16.08 GHz with the 5.48-GHz bandwidth. The excellent absorption properties of R-GO/SF/PANI nanocomposites indicated their great potential as microwave-absorbing materials. PMID:26969594

  2. Absorption spectra and photovoltaic characterization of chlorophyllins as sensitizers for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Calogero, Giuseppe; Citro, Ilaria; Crupi, Cristina; Di Marco, Gaetano

    2014-11-01

    Dye-sensitized solar cells (DSSCs) based on Chlorine-e6 (Chl-e6), a Chlorophyll a derivative, and Chl-e6 containing Cu, have been investigated by carrying out incident photon to current efficiency (IPCE) and current-voltage (I-V) measurements. The effect of the metallic ion and the influence of the solvent polarity on the dye aggregation and their absorption bands have been analysed by performing electronic absorption measurements. The dependence of the photoelectrochemical parameters of these DSSCs on the electrolyte by the addition of pyrimidine and/or pyrrole has been discussed in details. For the first time I-V curves for a DSSC based on copper Chl-e6 dye have been shown and compared with Zn based chlorophyllin. Furthermore, the performance of a Cu-Chl-e6 based DSSC has been deeply improved by a progressive optimization of the TiO2 multilayer photoanode overcoming the best data reported in literature so far for this dye. It's worth to emphasize that, the analysis reported in this paper supplies very useful information which paves the way to further detailed studies turned to the employment of natural pigments as sensitizers for solar cells.

  3. Absorption spectra and photovoltaic characterization of chlorophyllins as sensitizers for dye-sensitized solar cells.

    PubMed

    Calogero, Giuseppe; Citro, Ilaria; Crupi, Cristina; Di Marco, Gaetano

    2014-11-11

    Dye-sensitized solar cells (DSSCs) based on Chlorine-e6 (Chl-e6), a Chlorophyll a derivative, and Chl-e6 containing Cu, have been investigated by carrying out incident photon to current efficiency (IPCE) and current-voltage (I-V) measurements. The effect of the metallic ion and the influence of the solvent polarity on the dye aggregation and their absorption bands have been analysed by performing electronic absorption measurements. The dependence of the photoelectrochemical parameters of these DSSCs on the electrolyte by the addition of pyrimidine and/or pyrrole has been discussed in details. For the first time I-V curves for a DSSC based on copper Chl-e6 dye have been shown and compared with Zn based chlorophyllin. Furthermore, the performance of a Cu-Chl-e6 based DSSC has been deeply improved by a progressive optimization of the TiO2 multilayer photoanode overcoming the best data reported in literature so far for this dye. It's worth to emphasize that, the analysis reported in this paper supplies very useful information which paves the way to further detailed studies turned to the employment of natural pigments as sensitizers for solar cells. PMID:24892526

  4. Spectroscopic analysis of small organic molecules: A comprehensive near-edge x-ray-absorption fine-structure study of C{sub 6}-ring-containing molecules

    SciTech Connect

    Kolczewski, C.; Puettner, R.; Martins, M.; Schlachter, A.S.; Snell, G.; Sant'Anna, M.M.; Hermann, K.; Kaindl, G.

    2006-01-21

    We report high-resolution C 1s near-edge x-ray-absorption fine-structure (NEXAFS) spectra of the C{sub 6}-ring-containing molecules benzene (C{sub 6}H{sub 6}), 1,3- and 1,4-cyclohexadiene (C{sub 6}H{sub 8}), cyclohexene (C{sub 6}H{sub 10}), cyclohexane (C{sub 6}H{sub 12}), styrene (C{sub 8}H{sub 8}), and ethylbenzene (C{sub 8}H{sub 10}) which allow us to examine the gradual development of delocalization of the corresponding {pi} electron systems. Due to the high experimental resolution, vibrational progressions can be partly resolved in the spectra. The experimental spectra are compared with theoretical NEXAFS spectra obtained from density-functional theory calculations where electronic final-state relaxation is accounted for. The comparison yields very good agreement between theoretical spectra and experimental results. In all cases, the spectra can be described by excitations to {pi}*- and {sigma}*-type final-state orbitals with valence character, while final-state orbitals of Rydberg character make only minor contributions. The lowest C 1s{yields}1{pi}* excitation energy is found to agree in the (experimental and theoretical) spectra of all molecules except for 1,3-cyclohexadiene (C{sub 6}H{sub 8}) where an energy smaller by about 0.6 eV is obtained. The theoretical analysis can explain this result by different binding properties of this molecule compared to the others.

  5. Spectroscopic remote sensing of plant stress at leaf and canopy levels using the chlorophyll 680 nm absorption feature with continuum removal

    NASA Astrophysics Data System (ADS)

    Sanches, Ieda Del'Arco; Souza Filho, Carlos Roberto; Kokaly, Raymond Floyd

    2014-11-01

    This paper explores the use of spectral feature analysis to detect plant stress in visible/near infrared wavelengths. A time series of close range leaf and canopy reflectance data of two plant species grown in hydrocarbon-contaminated soil was acquired with a portable spectrometer. The ProSpecTIR-VS airborne imaging spectrometer was used to obtain far range hyperspectral remote sensing data over the field experiment. Parameters describing the chlorophyll 680 nm absorption feature (depth, width, and area) were derived using continuum removal applied to the spectra. A new index, the Plant Stress Detection Index (PSDI), was calculated using continuum-removed values near the chlorophyll feature centre (680 nm) and on the green-edge (560 and 575 nm). Chlorophyll feature's depth, width and area, the PSDI and a narrow-band normalised difference vegetation index were evaluated for their ability to detect stressed plants. The objective was to analyse how the parameters/indices were affected by increasing degrees of plant stress and to examine their utility as plant stress indicators at the remote sensing level (e.g. airborne sensor). For leaf data, PSDI and the chlorophyll feature area revealed the highest percentage (67-70%) of stressed plants. The PSDI also proved to be the best constraint for detecting the stress in hydrocarbon-impacted plants with field canopy spectra and airborne imaging spectroscopy data. This was particularly true using thresholds based on the ASD canopy data and considering the combination of higher percentage of stressed plants detected (across the thresholds) and fewer false-positives.

  6. Constraining the N2O5 UV absorption cross-section from spectroscopic trace gas measurements in the tropical mid-stratosphere

    NASA Astrophysics Data System (ADS)

    Kritten, L.; Butz, A.; Chipperfield, M. P.; Dorf, M.; Dhomse, S.; Hossaini, R.; Oelhaf, H.; Prados-Roman, C.; Wetzel, G.; Pfeilsticker, K.

    2014-02-01

    The absorption cross-section of N2O5, ?N2O5(?, T), which is known from laboratory measurements with the uncertainty of a factor of 2 (Table 4-2 in JPL-2011, Sander et al., 2011), was investigated by balloon-borne observations of the relevant trace gases in the tropical mid-stratosphere. The method relies on the observation of the diurnal variation of NO2 supported by detailed photochemical modelling of NOy (NOx(= NO + NO2) + NO3 + 2N2O5 + ClONO2 + HO2NO2 +BrONO2 + HNO3) photochemistry. Simulations are initialised with O3 measured by direct sun observations, the NOy partitioning from MIPAS-B (Michelson Interferometer for Passive Atmospheric Sounding-Balloon) observations in similar air masses at nighttime, and all other relevant species from simulations of the SLIMCAT chemical transport model (CTM). Best agreement between the simulated and observed diurnal increase of NO2 is found if the ?N2O5(?, T) is scaled by a factor of 1.6 0.8 in the UV-C (200-260 nm) and by a factor of 0.9 0.26 in the UV-B/A (260-350 nm), compared to current recommendations. In consequence, at 30 km altitude, the N2O5 lifetime against photolysis becomes a factor of 0.77 shorter at solar zenith angle (SZA) of 30 than using the recommended ?N2O5 (?, T), and stays more or less constant at SZAs of 60. Our scaled N2O5 photolysis frequency slightly reduces the lifetime (0.2-0.6%) of ozone in the tropical mid- and upper stratosphere, but not to an extent to be important for global ozone.

  7. An X-ray absorption spectroscopic study of the effect of bond covalency on the electronic structure of Gd2Ti(2-x)Sn(x)O7.

    PubMed

    Aluri, Esther Rani; Grosvenor, Andrew P

    2013-07-01

    The titanate and stannate pyrochlore-type oxides have been investigated because of their potential applications in different fields. Pyrochlore-type oxides exhibit a wide variety of properties such as fast ionic conduction, resistance to radiation induced structural damage, and ferro- and antiferro-magnetism. These properties mainly depend on the metal-oxygen bonding interactions and electronic structure of the materials, both of which can change with composition. The Gd2Ti(2-x)Sn(x)O7 (0 ≤ x ≤ 2) system was synthesized by the ceramic method and investigated by X-ray absorption near edge spectroscopy (XANES), which allows for the examination of the effect of substitution on bonding and the electronic structure of materials. Examination of metal K- and L3-edge XANES spectra from the Gd2Ti(2-x)Sn(x)O7 system allowed for the elucidation of how the metal-oxygen bond covalency effects the electronic structure of these materials with increasing Sn content. The ionic character of the Ti-O and Gd-O bonds increases while the Sn-O bond becomes more covalent as x increases in the formula, and resulted in changes in energy and/or line shape of the spectra. This study shows that the bonding interactions between metal and oxygen vary strongly with composition, which may affect the fast ionic conduction and resistance to radiation induced structural damage that has been previously reported for these materials. It was also observed in this study that the intensity of the intersite-hybrid peaks found in the pre-edge region of the Ti K-edge XANES spectra resulting from excitations of 1s electrons into next-nearest neighbour Ti 3d states decreased significantly with increasing Sn incorporation. PMID:23681175

  8. Organic matter characterization by infrared spectroscopic methods in lake sediment records from boreal and subarctic Sweden: Implications for long-term carbon cycling

    NASA Astrophysics Data System (ADS)

    Meyer-Jacob, Carsten; Rosn, Peter; Bindler, Richard

    2013-04-01

    Freshwater systems play an important role in the global carbon cycle. In this dynamic system, inorganic and organic carbon can be incorporated into biota, effluxed to the atmosphere or accumulated in sediments. The amount and composition of the carbon, derived from both aquatic and terrestrial sources, accumulated in sediments depend on the climatic and environmental conditions present in the lake and its catchment, and are thus sensitive to changes in, e.g., temperature, precipitation, vegetation and hydrological flow patterns. In this study, we show the application of infrared spectroscopic methods to qualitatively and quantitatively characterize organic matter stored in lake sediments with a focus on changes in the source of terrestrial-derived organic matter. Infrared spectroscopic methods facilitate a fast, cost-efficient and non-destructive analysis of minerogenic as well as organic sediment components. We applied three different infrared spectroscopic analyses - visible-near infrared spectroscopy (VNIRS; 25000-4000 cm-1), Fourier-transform infrared spectroscopy in the mid-IR region (FTIR; 3750-400 cm-1) and a combined Fourier-transformed infrared - thermal programmed desorption technique (FTIR-TPD; 3750-400 cm-1) - to Holocene sediment records from two Swedish lakes, Lng-lgsjn and Lake Koukkel, to reconstruct past changes in the organic matter composition. The infrared spectral information of these records indicate sections of different organic matter composition reflecting varying stages of the lake and landscape development. An early-Holocene mire development around the boreal lake Lng-lgsjn led to an increased input of organic matter from the catchment into the lake initiating an early natural lake acidification, whereas the subarctic Lake Koukkel has been affected by mire and potentially late-Holocene permafrost dynamics, which caused an increased and less variable input of allochthonous organic matter. Overall, variations in organic matter composition seem mainly driven by changes in the landscape rather than any direct effects of successive climate changes. Our findings emphasize that infrared spectroscopic methods are a promising tool for the fast and cost-effective characterization of organic matter in sediment samples, particularly with regard to the detection of qualitative differences between samples. An improved understanding of past variations in the organic matter composition and the related processes driving these changes is essential to further understand the interactions in the carbon cycle between the terrestrial and aquatic systems.

  9. Characterizing Quasar Outflows IV: Regulating Outflows Through X-ray and EUV Absorption

    NASA Astrophysics Data System (ADS)

    Derseweh, Jeffrey; Ganguly, R.; Richmond, J. M.; Stark, M. A.; Christenson, D. H.; Robbins, J. M.; Townsend, S. L.

    2012-05-01

    Galaxy evolution models have shown that quasars are a crucial ingredient in the evolution of massive galaxies. Outflows play a key role in the story of quasars and their host galaxies, by helping regulate the accretion process, the star-formation rate and mass of the host galaxy (i.e., feedback). The prescription for modeling outflows as a contributor to feedback requires knowledge of the outflow velocity, geometry, and column density. In particular, we need to understand how these depend on physical parameters and how much is determined stochastically (and with what distribution). For this purpose, we are examining a sample of 11000 z=1.7-2.0 quasars from the Sloan Digital Sky Survey. This redshift range permits the following from the SDSS spectra: (1) separation of objects that do and do not exhibit outflows; (2) classification/measurement of outflow properties (ionization, velocity, velocity width); and (3) measurements of UV emission line and continuum parameters. In this poster, we add photometry from the GALEX All-sky imaging survey, as well as the Chandra and ROSAT archives. These provide coverage of the rest-frame extreme ultraviolet, and soft X-ray bands. In an accompanying poster, we have subjectively divided these quasars into four categories: broad absorption-line quasars (2700 objects), associated absorption-line quasars (1700 objects), reddened quasars (160 objects), and unabsorbed/unreddened quasars (6300 objects). We are interested in testing the radiative-driving hypothesis that requires a suppression of X-ray flux in order to transfer momentum efficiently to the UV-absorbing gas. Hence, we explore how absorption in both the extreme ultraviolet and the soft X-ray bands correlate with properties of the UV outflows, quasar property, and changes in SED shape. This material is based upon work supported by the National Aeronautics and Space Administration under Grant No. 09-ADP09-0016 issued through the Astrophysics Data Analysis Program and by Chandra grant GO9-0120X.

  10. Chemical modification of TiO2 surfaces with methylsilanes and characterization by infrared absorption spectroscopy

    NASA Technical Reports Server (NTRS)

    Finklea, H. O.; Vithanage, R.

    1982-01-01

    Infrared absorption spectra of methylsilanes bonded to a TiO2 powder were obtained. The reacting silanes include Me sub (4-n)SiX sub n (n=1-4; X=Cl, OMe) and hexamethyldisilazane (HMDS). Reactions were performed on hydroxylated-but-anhydrous TiO2 surfaces in the gas phase. IR spectra confirm the presence of a bonded silane layer. Terminal surface OH groups are found to react more readily than bridging OH groups. By-products of the modification adsorp tenaciously to the surface. The various silanes show only small differences in their ability to sequester surface OH groups. Following hydrolysis in moist air, Si-OH groups are observed only for the tetrafunctional silanes.

  11. Characterization of Metalloproteins by High-throughput X-ray Absorption Spectroscopy

    SciTech Connect

    W Shi; M Punta; J Bohon; J Sauder; R DMello; M Sullivan; J Toomey; D Abel; M Lippi; et al.

    2011-12-31

    High-throughput X-ray absorption spectroscopy was used to measure transition metal content based on quantitative detection of X-ray fluorescence signals for 3879 purified proteins from several hundred different protein families generated by the New York SGX Research Center for Structural Genomics. Approximately 9% of the proteins analyzed showed the presence of transition metal atoms (Zn, Cu, Ni, Co, Fe, or Mn) in stoichiometric amounts. The method is highly automated and highly reliable based on comparison of the results to crystal structure data derived from the same protein set. To leverage the experimental metalloprotein annotations, we used a sequence-based de novo prediction method, MetalDetector, to identify Cys and His residues that bind to transition metals for the redundancy reduced subset of 2411 sequences sharing <70% sequence identity and having at least one His or Cys. As the HT-XAS identifies metal type and protein binding, while the bioinformatics analysis identifies metal-binding residues, the results were combined to identify putative metal-binding sites in the proteins and their associated families. We explored the combination of this data with homology models to generate detailed structure models of metal-binding sites for representative proteins. Finally, we used extended X-ray absorption fine structure data from two of the purified Zn metalloproteins to validate predicted metalloprotein binding site structures. This combination of experimental and bioinformatics approaches provides comprehensive active site analysis on the genome scale for metalloproteins as a class, revealing new insights into metalloprotein structure and function.

  12. Characterization and speciation of mercury-bearing mine wastes using X-ray absorption spectroscopy

    USGS Publications Warehouse

    Kim, C.S.; Brown, Gordon E., Jr.; Rytuba, J.J.

    2000-01-01

    Mining of mercury deposits located in the California Coast Range has resulted in the release of mercury to the local environment and water supplies. The solubility, transport, and potential bioavailability of mercury are controlled by its chemical speciation, which can be directly determined for samples with total mercury concentrations greater than 100 mg kg-1 (ppm) using X-ray absorption spectroscopy (XAS). This technique has the additional benefits of being non-destructive to the sample, element-specific, relatively sensitive at low concentrations, and requiring minimal sample preparation. In this study, Hg L(III)-edge extended X-ray absorption fine structure (EXAFS) spectra were collected for several mercury mine tailings (calcines) in the California Coast Range. Total mercury concentrations of samples analyzed ranged from 230 to 1060 ppm. Speciation data (mercury phases present and relative abundances) were obtained by comparing the spectra from heterogeneous, roasted (calcined) mine tailings samples with a spectral database of mercury minerals and sorbed mercury complexes. Speciation analyses were also conducted on known mixtures of pure mercury minerals in order to assess the quantitative accuracy of the technique. While some calcine samples were found to consist exclusively of mercuric sulfide, others contain additional, more soluble mercury phases, indicating a greater potential for the release of mercury into solution. Also, a correlation was observed between samples from hot-spring mercury deposits, in which chloride levels are elevated, and the presence of mercury-chloride species as detected by the speciation analysis. The speciation results demonstrate the ability of XAS to identify multiple mercury phases in a heterogeneous sample, with a quantitative accuracy of ??25% for the mercury-containing phases considered. Use of this technique, in conjunction with standard microanalytical techniques such as X-ray diffraction and electron probe microanalysis, is beneficial in the prioritization and remediation of mercury-contaminated mine sites. (C) 2000 Elsevier Science B.V.

  13. Characterization of metalloproteins by high-throughput X-ray absorption spectroscopy

    PubMed Central

    Shi, Wuxian; Punta, Marco; Bohon, Jen; Sauder, J. Michael; D'Mello, Rhijuta; Sullivan, Mike; Toomey, John; Abel, Don; Lippi, Marco; Passerini, Andrea; Frasconi, Paolo; Burley, Stephen K.; Rost, Burkhard; Chance, Mark R.

    2011-01-01

    High-throughput X-ray absorption spectroscopy was used to measure transition metal content based on quantitative detection of X-ray fluorescence signals for 3879 purified proteins from several hundred different protein families generated by the New York SGX Research Center for Structural Genomics. Approximately 9% of the proteins analyzed showed the presence of transition metal atoms (Zn, Cu, Ni, Co, Fe, or Mn) in stoichiometric amounts. The method is highly automated and highly reliable based on comparison of the results to crystal structure data derived from the same protein set. To leverage the experimental metalloprotein annotations, we used a sequence-based de novo prediction method, MetalDetector, to identify Cys and His residues that bind to transition metals for the redundancy reduced subset of 2411 sequences sharing <70% sequence identity and having at least one His or Cys. As the HT-XAS identifies metal type and protein binding, while the bioinformatics analysis identifies metal- binding residues, the results were combined to identify putative metal-binding sites in the proteins and their associated families. We explored the combination of this data with homology models to generate detailed structure models of metal-binding sites for representative proteins. Finally, we used extended X-ray absorption fine structure data from two of the purified Zn metalloproteins to validate predicted metalloprotein binding site structures. This combination of experimental and bioinformatics approaches provides comprehensive active site analysis on the genome scale for metalloproteins as a class, revealing new insights into metalloprotein structure and function. PMID:21482623

  14. Characterization and speciation of mercury-bearing mine wastes using X-ray absorption spectroscopy.

    PubMed

    Kim, C S; Brown, G E; Rytuba, J J

    2000-10-16

    Mining of mercury deposits located in the California Coast Range has resulted in the release of mercury to the local environment and water supplies. The solubility, transport, and potential bioavailability of mercury are controlled by its chemical speciation, which can be directly determined for samples with total mercury concentrations greater than 100 mg kg(-1) (ppm) using X-ray absorption spectroscopy (XAS). This technique has the additional benefits of being non-destructive to the sample, element-specific, relatively sensitive at low concentrations, and requiring minimal sample preparation. In this study, Hg L(III)-edge extended X-ray absorption fine structure (EXAFS) spectra were collected for several mercury mine tailings (calcines) in the California Coast Range. Total mercury concentrations of samples analyzed ranged from 230 to 1060 ppm. Speciation data (mercury phases present and relative abundances) were obtained by comparing the spectra from heterogeneous, roasted (calcined) mine tailings samples with a spectral database of mercury minerals and sorbed mercury complexes. Speciation analyses were also conducted on known mixtures of pure mercury minerals in order to assess the quantitative accuracy of the technique. While some calcine samples were found to consist exclusively of mercuric sulfide, others contain additional, more soluble mercury phases, indicating a greater potential for the release of mercury into solution. Also, a correlation was observed between samples from hot-spring mercury deposits, in which chloride levels are elevated, and the presence of mercury-chloride species as detected by the speciation analysis. The speciation results demonstrate the ability of XAS to identify multiple mercury phases in a heterogeneous sample, with a quantitative accuracy of +/-25% for the mercury-containing phases considered. Use of this technique, in conjunction with standard microanalytical techniques such as X-ray diffraction and electron probe microanalysis, is beneficial in the prioritization and remediation of mercury-contaminated mine sites. PMID:11036987

  15. Characterization of hydrogen absorption/desorption states on lithium-carbon-hydrogen system by neutron diffraction

    NASA Astrophysics Data System (ADS)

    Miyaoka, Hiroki; Itoh, Keiji; Fukunaga, Toshiharu; Ichikawa, Takayuki; Kojima, Yoshitsugu; Fuji, Hironobu

    2008-09-01

    The nanostructural hydrogenated graphite (CnanoHx) was synthesized from graphite by ball milling under hydrogen (H2) atmosphere. In this product, characteristic hydrogenated states in the form of polarized hydrocarbon groups (?CH, ?CH2, and ?CH3) are realized in the nanoscale. By synthesizing the composite of CnanoHx and lithium hydride (LiH), known as the Li ?C?H system, hydrogen was desorbed at 350C, which is a lower temperature compared to the decomposition temperature of each component. It is considered that this hydrogen desorption would be induced by destabilization of each hydrogen absorbed state due to an interaction between the polarized C ?H groups in CnanoHx and LiH. Therefore, in order to understand the hydrogen absorption/desorption mechanism of the Li ?C?H system, it is an important issue to investigate the change in the C ?H groups during hydrogen absorption/desorption reactions in the composite. The correlations among atoms contained in this composite are examined by neutron diffraction measurements, where the protium/deuterium (H/D) isotopic substitution was used to clarify the location of hydrogen atoms in this composite. Some C ?D and Li ?D correlations are found from the radial distribution function [RDF(r)] obtained by the neutron diffraction for the CnanoDx and LiD composite. After dehydrogenation, C ?C triple bond and Li ?C bond, ascribed to lithium carbide (Li2C2), are observed. Furthermore, the RDF(r ) corresponding to rehydrogenated composite indicates the presence of not only the Li ?D correlation but also the C ?D one.

  16. Characterization of metalloproteins by high-throughput X-ray absorption spectroscopy.

    PubMed

    Shi, Wuxian; Punta, Marco; Bohon, Jen; Sauder, J Michael; D'Mello, Rhijuta; Sullivan, Mike; Toomey, John; Abel, Don; Lippi, Marco; Passerini, Andrea; Frasconi, Paolo; Burley, Stephen K; Rost, Burkhard; Chance, Mark R

    2011-06-01

    High-throughput X-ray absorption spectroscopy was used to measure transition metal content based on quantitative detection of X-ray fluorescence signals for 3879 purified proteins from several hundred different protein families generated by the New York SGX Research Center for Structural Genomics. Approximately 9% of the proteins analyzed showed the presence of transition metal atoms (Zn, Cu, Ni, Co, Fe, or Mn) in stoichiometric amounts. The method is highly automated and highly reliable based on comparison of the results to crystal structure data derived from the same protein set. To leverage the experimental metalloprotein annotations, we used a sequence-based de novo prediction method, MetalDetector, to identify Cys and His residues that bind to transition metals for the redundancy reduced subset of 2411 sequences sharing <70% sequence identity and having at least one His or Cys. As the HT-XAS identifies metal type and protein binding, while the bioinformatics analysis identifies metal- binding residues, the results were combined to identify putative metal-binding sites in the proteins and their associated families. We explored the combination of this data with homology models to generate detailed structure models of metal-binding sites for representative proteins. Finally, we used extended X-ray absorption fine structure data from two of the purified Zn metalloproteins to validate predicted metalloprotein binding site structures. This combination of experimental and bioinformatics approaches provides comprehensive active site analysis on the genome scale for metalloproteins as a class, revealing new insights into metalloprotein structure and function. PMID:21482623

  17. Establishment and Characterization of an Omasal Epithelial Cell Model Derived from Dairy Calves for the Study of Small Peptide Absorption

    PubMed Central

    Xu, Qingbiao; Wu, Yueming; Liu, Hongyun; Xie, Yingming; Huang, Xinbei; Liu, Jianxin

    2014-01-01

    The objective of this study was to establish a primary culture of omasal epithelial cells (OECs) derived from dairy calves and to characterize its function in small peptide absorption. Bovine omasal tissues were obtained from newborn Chinese Holstein calves and digested with a 2.5% trypsin solution to obtain OECs. The isolated cells were later cultured in DMEM containing 10% fetal bovine serum, 5 ?g/ml insulin, 10 ng/ml epidermal growth factor, 100 U/ml penicillin, 100 ?g/ml streptomycin, 50 ?g/ml gentamycin and 2.5 ?g/ml amphotericin B. Hematoxylin and eosin staining of omasal tissue after digestion indicated that the cultured cells originated from the epithelial strata. Pure epithelial cells displayed an epithelial cell-like morphology, similar to cobblestone, with few visible fibroblasts and were cytokeratin 18-positive according to immunocytochemical analyses. The OECs were morphologically characterized with desmosomes, tight junctions and microvilli. These cells exhibited normal growth properties, as assessed using a cell growth curve, and were stably cultured for 10 passages. The OECs expressed the peptide transporter 1 (PEPT1) mRNA and absorbed intact glycylsarcosine (Gly-Sar). The uptake of Gly-Sar by OECs was pH-dependent with an optimal pH of 5.56.5. Furthermore, the uptake of Gly-Sar was also time-dependent, concentration-dependent and temperature-dependent. Moreover, PEPT1 was saturated with Gly-Sar at a concentration of 2.5 mM. The uptake via PEPT1 was higher compared with that via passive route at low substrate concentrations (<1.5 mM). This result suggested that PEPT1 contributed more to total small peptide absorption at low concentrations. In addition, this uptake could be competitively inhibited by methionine-glycine. Taken together, these data suggested that PEPT1 contributes to small peptide absorption in OECs. Thus, OECs may serve as a useful culture model for the study of the absorption of small peptides in bovine omasum. PMID:24633419

  18. Characterization of SEI layers on LiMn2O4 cathodes with in-situ spectroscopic ellipsometry

    SciTech Connect

    Lei, Jinglei; Li, Lingjie; Kostecki, Robert; Muller, Rolf; McLarnon, Frank

    2004-08-30

    In situ spectroscopic ellipsometry was employed to study the initial stage of SEI layer formation on thin-film LiMn{sub 2}O{sub 4} electrodes. It was found that the SEI layer formed immediately upon exposure of the electrode to EC/DMC (1:1 by vol) 1.0 M LiPF{sub 6} electrolyte. The SEI layer thickness then increased in proportion to a logarithmic function of elapsed time. In comparison, the SEI layer thickness on a cycled electrode increased in proportion to a linear function of the number of cycles.

  19. Spectroscopic and structural characterization of three silaisocyanides: exploring an elusive class of reactive molecules at high resolution.

    PubMed

    Thorwirth, Sven; Kaiser, Ralf I; Crabtree, Kyle N; McCarthy, Michael C

    2015-06-30

    Silaisocyanoacetylene, HCCNSi, silaisocyanodiacetylene, HC4NSi, and silaisocyanogen, NCNSi, have been identified spectroscopically for the first time. All three transient species were observed at high spectral resolution at centimeter wavelengths (5-40 GHz) by microwave spectroscopy. From detection of less abundant isotopic species and high-level quantum-chemical calculations, accurate empirical equilibrium structures have been derived for HCCNSi and NCNSi. All three molecules are promising candidates for future radio astronomical detection owing in part to large calculated dipole moments. PMID:26083592

  20. Development of Cellular Absorptive Tracers (CATs) for a Quantitative Characterization of the Complexity of Nanoscale Biological Systems

    NASA Astrophysics Data System (ADS)

    Choi, J.; Saripalli, P.; Meldrum, D.; Lee, S.

    2005-12-01

    A new method is proposed in this study, which is entitled Cellular Absorptive Tracers (CATs; PNNL Invention Disclosure; Saripalli, P. 2001), to characterize the extent, location, and morphology of cell mass in microelectromechanical systems (MEMS), by preferentially absorbing into the living or lysed cells or adsorbing at the cell surfaces. The CATs were used to demonstrate their utility to quantitatively characterize the biomass, its location, and morphology in MEMS. A series of experiments had conducted, using different number/types of cells and morphologic distributions (e.g., concentrated vs. disperse) within the microenvironmental chamber. The experiments were conducted such that, simultaneously with CATs characterization, a number of metabolic parameters (such as oxygen, CO2, glucose, pH, methanol, formate and small molecule metabolites, etc.) also were measured by fluorescence microscopy (Lidstrom and Meldrum, Nature, 2003). Results of partition and transport experiments show that adsorption of a CAT molecule into the cellular mass results in its retardation during flow, which is a good measure of the biomass quantity and distribution. The molecules chosen were used to demonstrate their utility to quantitatively characterize the biomass, its location and morphology in MEMS. The results yield first-of-their-kind data sets relating metabolic parameters to location, heterogeneity, and morphology of cells. The data were used to obtain quantitative information needed for the characterization of biomass in MEMS, and to develop the theory relating the cellular phenomena of interest to cellular heterogeneity and morphology. The proposed research contributes a new set of tools for a rapid, noninvasive characterization of nano-scale biological systems.

  1. Spectroscopic Low Coherence Interferometry

    NASA Astrophysics Data System (ADS)

    Bosschaart, Nienke; van Leeuwen, T. G.; Aalders, Maurice C.; Hermann, Boris; Drexler, Wolfgang; Faber, Dirk J.

    Low-coherence interferometry (LCI) allows high-resolution volumetric imaging of tissue morphology and provides localized optical properties that can be related to the physiological status of tissue. This chapter discusses the combination of spatial and spectroscopic information by means of spectroscopic OCT (sOCT) and low-coherence spectroscopy (LCS). We describe the theory behind these modalities for the assessment of spatially resolved optical absorption and (back)scattering coefficient spectra. These spectra can be used for the highly localized quantification of chromophore concentrations and assessment of tissue organization on (sub)cellular scales. This leads to a wealth of potential clinical applications, ranging from neonatology for the determination of billibrubin concentrations, to oncology for the optical assessment of the aggressiveness of a cancerous lesion.

  2. Synthesis, spectroscopic characterization, DFT studies, and antibacterial and antitumor activities of a novel water soluble Pd(II) complex with L-alliin

    NASA Astrophysics Data System (ADS)

    Abbehausen, Camilla; Sucena, Suelen F.; Lancellotti, Marcelo; Heinrich, Tassiele A.; Abro, Emiliana P.; Costa-Neto, Claudio M.; Formiga, Andr L. B.; Corbi, Pedro P.

    2013-03-01

    A new water soluble Pd(II) complex with L-alliin (S-allyl-L-cysteine sulfoxide) was obtained and characterized by a set of chemical and spectroscopic measurements. Elemental and mass spectrometric data are consistent with the formula [Pd(C6H10NO3S)2]. The 1H and 13C nuclear magnetic resonance (NMR) data, [1H-15N] two dimensional (2D) NMR and infrared spectroscopic measurements indicate coordination of the ligand to Pd(II) through N and O atoms. DFT studies showed that the trans isomer is the most stable and preferred geometry for the complex. The complex is soluble in water and dimethylsulfoxide. An antibiogram assay revealed that the complex possess antibacterial activity against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus bacterial strains in the range 125-500 ?g mL-1. Antitumor assays revealed that the complex presents cytotoxic activity over HeLa cells with an estimated IC50 of 20 ?mol L-1.

  3. Characterization of the Electronic Structure of Silicon Nanoparticles Using X-ray Absorption and Emission

    SciTech Connect

    Vaverka, A M

    2008-07-15

    Resolving open questions regarding transport in nanostructures can have a huge impact on a broad range of future technologies such as light harvesting for energy. Silicon has potential to be used in many of these applications. Understanding how the band edges of nanostructures move as a function of size, surface termination and assembly is of fundamental importance in understanding the transport properties of these materials. In this thesis work I have investigated the change in the electronic structure of silicon nanoparticle assemblies as the surface termination is changed. Nanoparticles are synthesized using a thermal evaporation technique and sizes are determined using atomic force microscopy (AFM). By passivating the particles with molecules containing alcohol groups we are able to modify the size dependent band edge shifts. Both the valence and conduction bands are measured using synchrotron based x-ray absorption spectroscopy (XAS) and soft x-ray fluorescence (SXF) techniques. Particles synthesized via recrystallization of amorphous silicon/SiO{sub 2} multilayers of thicknesses below 10 nm are also investigated using the synchrotron techniques. These samples also show quantum confinement effects but the electronic structure is different from those synthesized via evaporation methods. The total bandgap is determined for all samples measured. The origins of these differences in the electronic structures are discussed.

  4. Spatiotemporal characterization of interfacial Faraday waves by means of a light absorption technique.

    PubMed

    Kityk, A V; Embs, J; Mekhonoshin, V V; Wagner, C

    2005-09-01

    We present measurements of the complete spatiotemporal Fourier spectrum of Faraday waves. The Faraday waves are generated at the interface of two immiscible index matched liquids of different density. By use of a light absorption technique we are able to determine the bifurcation scenario from the flat surface to the patterned state for each complex spatial and temporal Fourier component separately. The surface spectra at onset are found to be in good agreement with the predictions from the linear stability analysis. For the nonlinear state our measurements show in a direct manner how energy is transferred from lower to higher harmonics and we quantify the nonlinear coupling coefficients. Furthermore we find that the nonlinear coupling generates static components in the temporal Fourier spectrum leading thus to a contribution of a nonoscillating permanent sinusoidal deformed surface state. A comparison of hexagonal and rectangular patterns reveals that spatial resonance can give rise to a spectrum that violates the temporal resonance conditions given by the weakly nonlinear theory. PMID:16241550

  5. Fourier transform infrared absorption spectroscopy characterization of gaseous atmospheric pressure plasmas with 2 mm spatial resolution

    SciTech Connect

    Laroche, G.; Vallade, J.; Bazinette, R.; Hernandez, E.; Hernandez, G.; Massines, F.; Nijnatten, P. van

    2012-10-15

    This paper describes an optical setup built to record Fourier transform infrared (FTIR) absorption spectra in an atmospheric pressure plasma with a spatial resolution of 2 mm. The overall system consisted of three basic parts: (1) optical components located within the FTIR sample compartment, making it possible to define the size of the infrared beam (2 mm Multiplication-Sign 2 mm over a path length of 50 mm) imaged at the site of the plasma by (2) an optical interface positioned between the spectrometer and the plasma reactor. Once through the plasma region, (3) a retro-reflector module, located behind the plasma reactor, redirected the infrared beam coincident to the incident path up to a 45 Degree-Sign beamsplitter to reflect the beam toward a narrow-band mercury-cadmium-telluride detector. The antireflective plasma-coating experiments performed with ammonia and silane demonstrated that it was possible to quantify 42 and 2 ppm of these species in argon, respectively. In the case of ammonia, this was approximately three times less than this gas concentration typically used in plasma coating experiments while the silane limit of quantification was 35 times lower. Moreover, 70% of the incoming infrared radiation was focused within a 2 mm width at the site of the plasma, in reasonable agreement with the expected spatial resolution. The possibility of reaching this spatial resolution thus enabled us to measure the gaseous precursor consumption as a function of their residence time in the plasma.

  6. Americium characterization by X-ray fluorescence and absorption spectroscopy in plutonium uranium mixed oxide

    NASA Astrophysics Data System (ADS)

    Degueldre, Claude; Cozzo, Cedric; Martin, Matthias; Grolimund, Daniel; Mieszczynski, Cyprian

    2013-06-01

    Plutonium uranium mixed oxide (MOX) fuels are currently used in nuclear reactors. The actinides in these fuels need to be analyzed after irradiation for assessing their behaviour with regard to their environment and the coolant. In this work the study of the atomic structure and next-neighbour environment of Am in the (Pu,U)O2 lattice in an irradiated (60 MW d kg-1) MOX sample was performed employing micro-X-ray fluorescence (-XRF) and micro-X-ray absorption fine structure (-XAFS) spectroscopy. The chemical bonds, valences and stoichiometry of Am (0.66 wt%) are determined from the experimental data gained for the irradiated fuel material examined in its peripheral zone (rim) of the fuel. In the irradiated sample Am builds up as Am3+ species within an [AmO8]13- coordination environment (e.g. >90%) and no (<10%) Am(IV) or (V) can be detected in the rim zone. The occurrence of americium dioxide is avoided by the redox buffering activity of the uranium dioxide matrix.

  7. Electronic transport characterization of silicon wafers by combination of modulated free carrier absorption and photocarrier radiometry

    NASA Astrophysics Data System (ADS)

    Huang, Qiuping; Li, Bincheng

    2011-01-01

    A combined modulated free carrier absorption (MFCA) and photocarrier radiometry (PCR) technique is developed to determine simultaneously the electronic transport properties (carrier diffusion coefficient, carrier lifetime, and front surface recombination velocity) of silicon wafers. Comparative computer simulations are carried out to investigate how the experimental measurement errors affect the simultaneous determination of the electronic transport parameters by introducing random or systematic errors into the simulated MFCA and PCR data and statistically analyzing the fitted results, by means of separate MFCA and PCR, as well as the combined MFCA and PCR through fitting the experimental dependences of signal amplitudes and phases to the corresponding theoretical models via a multiparameter fitting procedure, respectively. The simulation results show that with the combined MFCA and PCR the effect of experimental errors on the simultaneous determination of the transport parameters is significantly reduced and therefore the accuracy of the fitted results is greatly improved. Experiments with two c-Si wafers with the three methods were performed and the results were compared. The experimental results showed that the combined MFCA and PCR provided the most accurate fitted transport parameters, in agreement with the simulation results.

  8. Fourier transform infrared absorption spectroscopy characterization of gaseous atmospheric pressure plasmas with 2 mm spatial resolution

    NASA Astrophysics Data System (ADS)

    Laroche, G.; Vallade, J.; Bazinette, R.; van Nijnatten, P.; Hernandez, E.; Hernandez, G.; Massines, F.

    2012-10-01

    This paper describes an optical setup built to record Fourier transform infrared (FTIR) absorption spectra in an atmospheric pressure plasma with a spatial resolution of 2 mm. The overall system consisted of three basic parts: (1) optical components located within the FTIR sample compartment, making it possible to define the size of the infrared beam (2 mm × 2 mm over a path length of 50 mm) imaged at the site of the plasma by (2) an optical interface positioned between the spectrometer and the plasma reactor. Once through the plasma region, (3) a retro-reflector module, located behind the plasma reactor, redirected the infrared beam coincident to the incident path up to a 45° beamsplitter to reflect the beam toward a narrow-band mercury-cadmium-telluride detector. The antireflective plasma-coating experiments performed with ammonia and silane demonstrated that it was possible to quantify 42 and 2 ppm of these species in argon, respectively. In the case of ammonia, this was approximately three times less than this gas concentration typically used in plasma coating experiments while the silane limit of quantification was 35 times lower. Moreover, 70% of the incoming infrared radiation was focused within a 2 mm width at the site of the plasma, in reasonable agreement with the expected spatial resolution. The possibility of reaching this spatial resolution thus enabled us to measure the gaseous precursor consumption as a function of their residence time in the plasma.

  9. Fourier transform infrared absorption spectroscopy characterization of gaseous atmospheric pressure plasmas with 2 mm spatial resolution.

    PubMed

    Laroche, G; Vallade, J; Bazinette, R; van Nijnatten, P; Hernandez, E; Hernandez, G; Massines, F

    2012-10-01

    This paper describes an optical setup built to record Fourier transform infrared (FTIR) absorption spectra in an atmospheric pressure plasma with a spatial resolution of 2 mm. The overall system consisted of three basic parts: (1) optical components located within the FTIR sample compartment, making it possible to define the size of the infrared beam (2 mm × 2 mm over a path length of 50 mm) imaged at the site of the plasma by (2) an optical interface positioned between the spectrometer and the plasma reactor. Once through the plasma region, (3) a retro-reflector module, located behind the plasma reactor, redirected the infrared beam coincident to the incident path up to a 45° beamsplitter to reflect the beam toward a narrow-band mercury-cadmium-telluride detector. The antireflective plasma-coating experiments performed with ammonia and silane demonstrated that it was possible to quantify 42 and 2 ppm of these species in argon, respectively. In the case of ammonia, this was approximately three times less than this gas concentration typically used in plasma coating experiments while the silane limit of quantification was 35 times lower. Moreover, 70% of the incoming infrared radiation was focused within a 2 mm width at the site of the plasma, in reasonable agreement with the expected spatial resolution. The possibility of reaching this spatial resolution thus enabled us to measure the gaseous precursor consumption as a function of their residence time in the plasma. PMID:23126767

  10. Structural characterization of 1,1,3,3-tetramethylguanidinium chloride ionic liquid by reversible SO2 gas absorption.

    PubMed

    Berg, Rolf W; Harris, Pernille; Riisager, Anders; Fehrmann, Rasmus

    2013-11-01

    A unique new ionic liquid-gas adduct solid state compound formed between 1,1,3,3-tetramethylguanidinium chloride ([tmgH]Cl) and sulfur dioxide has been characterized by X-ray diffraction and Raman spectroscopy. The structure contains SO2 molecules of near normal structure kept at their positions by Cl-S interactions. The crystals belong in the orthorhombic system, space group Pbcn, with unit cell dimensions of a = 15.6908(10) , b = 9.3865(6) , and c = 14.1494(9) , angles ? = ? = ? = 90, and Z = 8 at 120 K. The [tmgH]Cl has a very high absorption capacity of nearly 3 mol of SO2 per mol of [tmgH]Cl at 1 bar of SO2 and at room temperature. However, part of the absorbed SO2 was liberated during the crystallization, probably because the crystal only accommodates one molecule of SO2 per [tmgH]Cl. The nature of the high absorption capacity of [tmgH]Cl as well as of the homologous compounds with bromide and iodide are discussed. Some of these salts may prove useful as reversible absorbents of SO2 in industrial flue gases. PMID:24088034

  11. Synthesis and characterizations of ultra-small ZnS and Zn (1- x) Fe xS quantum dots in aqueous media and spectroscopic study of their interactions with bovine serum albumin

    NASA Astrophysics Data System (ADS)

    Khani, Omid; Rajabi, Hamid Reza; Yousefi, Mohammad Hasan; Khosravi, Ali Azam; Jannesari, Mohammad; Shamsipur, Mojtaba

    2011-07-01

    This work reports a new experimental methodology for the synthesis of ultra small zinc sulfide and iron doped zinc sulfide quantum dots in aqueous media. The nanoparticles were obtained using a simple procedure based on the precipitation of ZnS in aqueous solution in the presence of 2-mercaptoethanol as a capping agent, at room temperature. The effect of Fe 3+ ion concentration as dopant on the optical properties of ZnS was studied. The size of quantum dots was determined to be about 1 nm, using scanning tunneling microscopy. The synthesized nanoparticles were characterized by X-ray diffraction, UV-Vis absorption and photoluminescence emission spectroscopies. The presence and amount of iron impurity in the structure of Zn (1- x) Fe xS nanocrystals were confirmed by atomic absorption spectrometry. A blue shift in band-gap of ZnS was observed upon increasing incorporation of Fe 3+ ion in the iron doped zinc sulfide quantum dots. The photoluminescence investigations showed that, in the case of iron doped ZnS nanoparticles, the emission band of pure ZnS nanoparticles at 427 nm shifts to 442 nm with appearance of a new sharp emission band around 532 nm. The X-ray diffraction analysis indicated that the iron doped nanoparticles are crystalline, with cubic zinc blend structure, having particle diameters of 1.7 022 nm. Finally, the interaction of the synthesized nanoparticles with bovine serum albumin was investigated at pH 7.2. The UV-Vis absorption and fluorescence spectroscopic methods were applied to compare the optical properties of pure and iron doped ZnS quantum dots upon interaction with BSA. It was proved that, in both cases, the fluorescence quenching of BSA by the quantum dots is mainly a result of the formation of QDs-BSA complex in solution. In the steady-state fluorescence studies, the interaction parameters including binding constants ( Ka), number of binding sites ( n), quenching constants ( KSV), and bimolecular quenching rate constants ( kq) were determined at three different temperatures and the results were then used to evaluate the corresponding thermodynamic parameters ? H, ? S and ? G.

  12. Synthesis and characterizations of ultra-small ZnS and Zn(1-x)Fe(x)S quantum dots in aqueous media and spectroscopic study of their interactions with bovine serum albumin.

    PubMed

    Khani, Omid; Rajabi, Hamid Reza; Yousefi, Mohammad Hasan; Khosravi, Ali Azam; Jannesari, Mohammad; Shamsipur, Mojtaba

    2011-07-01

    This work reports a new experimental methodology for the synthesis of ultra small zinc sulfide and iron doped zinc sulfide quantum dots in aqueous media. The nanoparticles were obtained using a simple procedure based on the precipitation of ZnS in aqueous solution in the presence of 2-mercaptoethanol as a capping agent, at room temperature. The effect of Fe(3+) ion concentration as dopant on the optical properties of ZnS was studied. The size of quantum dots was determined to be about 1nm, using scanning tunneling microscopy. The synthesized nanoparticles were characterized by X-ray diffraction, UV-Vis absorption and photoluminescence emission spectroscopies. The presence and amount of iron impurity in the structure of Zn((1-x))Fe(x)S nanocrystals were confirmed by atomic absorption spectrometry. A blue shift in band-gap of ZnS was observed upon increasing incorporation of Fe(3+) ion in the iron doped zinc sulfide quantum dots. The photoluminescence investigations showed that, in the case of iron doped ZnS nanoparticles, the emission band of pure ZnS nanoparticles at 427nm shifts to 442nm with appearance of a new sharp emission band around 532nm. The X-ray diffraction analysis indicated that the iron doped nanoparticles are crystalline, with cubic zinc blend structure, having particle diameters of 1.7022nm. Finally, the interaction of the synthesized nanoparticles with bovine serum albumin was investigated at pH 7.2. The UV-Vis absorption and fluorescence spectroscopic methods were applied to compare the optical properties of pure and iron doped ZnS quantum dots upon interaction with BSA. It was proved that, in both cases, the fluorescence quenching of BSA by the quantum dots is mainly a result of the formation of QDs-BSA complex in solution. In the steady-state fluorescence studies, the interaction parameters including binding constants (K(a)), number of binding sites (n), quenching constants ( [Formula: see text] ), and bimolecular quenching rate constants (k(q)) were determined at three different temperatures and the results were then used to evaluate the corresponding thermodynamic parameters ?H, ?S and ?G. PMID:21482179

  13. Characterization of selective binding of alkali cations with carboxylate by x-ray absorption spectroscopy of liquid microjets

    PubMed Central

    Uejio, Janel S.; Schwartz, Craig P.; Duffin, Andrew M.; Drisdell, Walter S.; Cohen, Ronald C.; Saykally, Richard J.

    2008-01-01

    We describe an approach for characterizing selective binding between oppositely charged ionic functional groups under biologically relevant conditions. Relative shifts in K-shell x-ray absorption spectra of aqueous cations and carboxylate anions indicate the corresponding binding strengths via perturbations of carbonyl antibonding orbitals. XAS spectra measured for aqueous formate and acetate solutions containing lithium, sodium, and potassium cations reveal monotonically stronger binding of the lighter metals, supporting recent results from simulations and other experiments. The carbon K-edge spectra of the acetate carbonyl feature centered near 290 eV clearly indicate a preferential interaction of sodium versus potassium, which was less apparent with formate. These results are in accord with the Law of Matching Water Affinities, relating relative hydration strengths of ions to their respective tendencies to form contact ion pairs. Density functional theory calculations of K-shell spectra support the experimental findings. PMID:18463292

  14. Characterization of selective binding of alkali cations with carboxylate by x-ray absorption spectroscopy of liquid microjets

    SciTech Connect

    Saykally, Richard J; Uejio, Janel S.; Schwartz, Craig P.; Duffin, Andrew M.; Drisdell, Walter S.; Cohen, Ronald C.; Saykally, Richard J.

    2008-01-08

    We describe an approach for characterizing selective binding between oppositely charged ionic functional groups under biologically relevant conditions. Relative shifts in K-shell x-ray absorption spectra of aqueous cations and carboxylate anions indicate the corresponding binding strengths via perturbations of carbonyl antibonding orbitals. XAS spectra measured for aqueous formate and acetate solutions containing lithium, sodium, and potassium cations reveal monotonically stronger binding of the lighter metals, supporting recent results from simulations and other experiments. The carbon K-edge spectra of the acetate carbonyl feature centered near 290 eV clearly indicate a preferential interaction of sodium versus potassium, which was less apparent with formate. These results are in accord with the Law of Matching Water Affinities, relating relative hydration strengths of ions to their respective tendencies to form contact ion pairs. Density functional theory calculations of K-shell spectra support the experimental findings.

  15. Observation of x-ray absorption magnetic circular dichroism in well-characterized iron-cobalt-platinum multilayers

    SciTech Connect

    Jankowski, A.F.; Waddill, G.D.; Tobin, J.G.

    1993-04-01

    Magnetic circular dichroism in the Fe 2p x-ray absorption is observed in multilayers of(Fe9.5{Angstrom}/Pt9.5{Angstrom}){sub 92}. The magnetization and helicity are both in the plane of this multilayer which is prepared by magnetron sputter deposition. This sample is part of a study to examine magnetization in the ternary multilayer system of FeCo/Pt. Lattice and layer pair spacings are measured using x-ray scattering. The atomic concentration profiles of the multilayer films are characterized using Auger electron spectroscopy coupled with depth profiling. Conventional and high resolution transmission electron microscopy are used to examine the thin film, growth morphology and atomic structure.

  16. Gold Nanoclusters Entrapped in the Alpha-Cages of Y-Zeolites: Structural Characterization By X-Ray Absorption Spectroscopy

    SciTech Connect

    Fierro-Gonzalez, J.C.; Hao, Y.; Gates, B.C.

    2009-06-03

    Au(CH{sub 3}){sub 2}(C{sub 5}H{sub 7}O{sub 2}) was used as a precursor to synthesize mononuclear gold complexes in faujasites, NaY zeolite, and dealuminated Y zeolite. Treatment of these supported complexes in flowing helium as the temperature was increased led to the gradual reduction of the gold and formation of gold nanoclusters in each zeolite, which were characterized by X-ray absorption spectroscopy. After treatment at the highest temperature, 573 K, the average diameters of the gold clusters were approximately 10 and 8 {angstrom} in NaY zeolite and dealuminated Y zeolite, respectively; these clusters are smaller than the diameters of the {alpha}-cages of the zeolite. The results indicate that the supported clusters were trapped within these cages and that the cages limited their sizes; in contrast, clusters formed similarly on the surfaces of metal oxides are significantly larger than those formed in the zeolites.

  17. The PtAl{sup −} and PtAl{sub 2}{sup −} anions: Theoretical and photoelectron spectroscopic characterization

    SciTech Connect

    Zhang, Xinxing; Ganteför, Gerd; Bowen, Kit H. E-mail: ana@chem.ucla.edu; Alexandrova, Anastassia N. E-mail: ana@chem.ucla.edu

    2014-04-28

    We report a joint photoelectron spectroscopic and theoretical study of the PtAl{sup −} and PtAl{sub 2}{sup −} anions. The ground state structures and electronic configurations of these species were identified to be C{sub ∞v}, {sup 1}Σ{sup +} for PtAl{sup −}, and C{sub 2v}, {sup 2}B{sub 1} for PtAl{sub 2}{sup −}. Structured anion photoelectron spectra of these clusters were recorded and interpreted using ab initio calculations. Good agreement between theory and experiment was found. All experimental features were successfully assigned to one-electron transitions from the ground state of the anions to the ground or excited states of the corresponding neutral species.

  18. Spectroscopic characterization of different structural forms of the new promising energetic material FOX-7 in different solvents

    NASA Astrophysics Data System (ADS)

    imkov, Ludmila; oral, Michal; Lupai, Karol; Ludvk, Ji?

    2015-03-01

    UV-vis, IR and NMR spectroscopy were utilized as direct monitoring techniques for structure changes of a new promising energetic material FOX-7 in different protic and aprotic solvents. The dissolved FOX-7 indicates changes in molecular structure as compared with that in solid-state. The push-pull properties of the molecule together with the effects of solvents result in charge separated zwitterion formed in solution. By combination of different spectroscopic techniques, structural changes of charge-separated molecule of FOX-7 were described in dependence on the solvent properties, temperature, proton activity and concentration. From the analytical point of view, the lowest detectable concentration of FOX-7 using UV-vis spectra was determined to approximately 6 10-7 mol L-1.

  19. Mapping tropical biodiversity using spectroscopic imagery : characterization of structural and chemical diversity with 3-D radiative transfer modeling

    NASA Astrophysics Data System (ADS)

    Feret, J. B.; Gastellu-Etchegorry, J. P.; Lefvre-Fonollosa, M. J.; Proisy, C.; Asner, G. P.

    2014-12-01

    The accelerating loss of biodiversity is a major environmental trend. Tropical ecosystems are particularly threatened due to climate change, invasive species, farming and natural resources exploitation. Recent advances in remote sensing of biodiversity confirmed the potential of high spatial resolution spectroscopic imagery for species identification and biodiversity mapping. Such information bridges the scale-gap between small-scale, highly detailed field studies and large-scale, low-resolution satellite observations. In order to produce fine-scale resolution maps of canopy alpha-diversity and beta-diversity of the Peruvian Amazonian forest, we designed, applied and validated a method based on spectral variation hypothesis to CAO AToMS (Carnegie Airborne Observatory Airborne Taxonomic Mapping System) images, acquired from 2011 to 2013. There is a need to understand on a quantitative basis the physical processes leading to this spectral variability. This spectral variability mainly depends on canopy chemistry, structure, and sensor's characteristics. 3D radiative transfer modeling provides a powerful framework for the study of the relative influence of each of these factors in dense and complex canopies. We simulated series of spectroscopic images with the 3D radiative model DART, with variability gradients in terms of leaf chemistry, individual tree structure, spatial and spectral resolution, and applied methods for biodiversity mapping. This sensitivity study allowed us to determine the relative influence of these factors on the radiometric signal acquired by different types of sensors. Such study is particularly important to define the domain of validity of our approach, to refine requirements for the instrumental specifications, and to help preparing hyperspectral spatial missions to be launched at the horizon 2015-2025 (EnMAP, PRISMA, HISUI, SHALOM, HYSPIRI, HYPXIM). Simulations in preparation include topographic variations in order to estimate the robustness of image processing methods for mountainous ecosystems.

  20. Synthesis, spectroscopic characterization, potentiometric studies, cytotoxic studies and molecular docking studies of DNA binding of transition metal complexes with 1,1-diaminopropane-Schiff base

    NASA Astrophysics Data System (ADS)

    Alaghaz, Abdel-Nasser M. A.; El-Sayed, Badr A.; El-Henawy, Ahmed A.; Ammar, Reda A. A.

    2013-03-01

    A new series of Schiff base transition metal complexes with N,N'-bis(2-hydroxybenzylidene)-1,1-diaminopropane (H2BHBDAP) have been prepared and characterized by elemental analysis, spectroscopic and magnetic measurements. Protonation constants of Schiff base and stability constants of their binary metal complexes have been determined potentiometrically in 50% DMSO-water media at 25 C and ionic strength 0.10 M sodium perchlorate. Quantum chemical calculations were performed with semi-empirical method to find the optimum geometry of the ligand and its complexes. Additionally in silico, the Docking studies and the calculated pharmacokinetic parameters show promising futures for application of the ligand and complexes as high potency agents for DNA binding activity.

  1. Spectroscopic characterization of Co3O4 catalyst doped with CeO2 and PdO for methane catalytic combustion.

    PubMed

    Jod?owski, P J; J?drzejczyk, R J; Rogulska, A; Wach, A; Ku?trowski, P; Sitarz, M; ?ojewski, T; Ko?odziej, A; ?ojewska, J

    2014-10-15

    The study deals with the XPS, Raman and EDX characterization of a series of structured catalysts composed of cobalt oxides promoted by palladium and cerium oxides. The aim of the work was to relate the information gathered from spectroscopic analyses with the ones from kinetic tests of methane combustion to establish the basic structure-activity relationships for the catalysts studied. The most active catalyst was the cobalt oxide doped with little amount of palladium and wins a confrontation with pure palladium oxide catalyst which is commercially used in converters for methane. The analyses Raman and XPS analyses showed that this catalyst is composed of a cobalt spinel and palladium oxide. The quantitative approach to the composition of the catalysts by XPS and EDX methods revealed that the surface of palladium doped cobalt catalyst is enriched with palladium oxide which provides a great number of active centres for methane combustion indicated by kinetic parameters. PMID:24913565

  2. Monitoring and characterization of compost obtained from household waste and pine sawdust in a facultative reactor by conventional and spectroscopic analyses.

    PubMed

    de Campos, Sandro Xavier; Resseti, Rolan Roney; Zittel, Rosimara

    2014-12-01

    This study proposes a new facultative reactor configuration for the treatment of organic household waste and pine sawdust. The process was monitored and the compost characterized by conventional (temperature, moisture, pH, ash content and ratio C/N) conjugated with spectroscopic analyses (ultraviolet (UV)/visible (Vis) and infrared (IR)) and germination index. The spectroscopy results revealed enrichment of carbon-carbon unsaturation structures and a degradation of the aliphatic structures. The results showed that stability of the final product was reached after 90 days and that the compost obtained presents substantial richness of stabilized organic matter and an absence of toxicity, so it may be considered as an organic fertilizer. Finally, this study led to the conclusion that the reactor proposed can be a promising technology for the management of organic household waste and sawdust. PMID:25106532

  3. Synthesis, Spectroscopic Characterization, X-Ray Structure, and DFT Calculations of Some New 1,4-Dihydro-2,6-Dimethyl-3,5 -Pyridinedicarboxamides

    PubMed Central

    Li, Yi; Liu, Yuan-Yuan; Chen, Xue-Jun; Xiong, Xiao-Hui; Li, Fang-Shi

    2014-01-01

    A series of novel 1,4-dihydro-2,6- dimethyl-3,5-pyridinedicarboxamides were synthesized and characterized by infrared absorption spectrum (IR), proton nuclear magnetic resonance (1H NMR), elemental analysis, ultraviolet spectrum (UV), and fluorescence techniques, together with X-ray single crystal diffraction. The results of density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations provided a reasonable explanation on the molecular structures, the molecular frontier orbital, and the spectra of electronic absorption and emission. The present work will be helpful to systematically understanding of the structures and the optical properties of 1,4-dihydropyridines for studying the structure-activity relationship and to develop new drugs and their analytical methods. PMID:24625887

  4. Quest for Environmentally-Benign Ligands for Actinide Separations: Thermodynamic, Spectroscopic, and Structural Characterization of U(VI) Complexes with Oxa-Diamide and Related Ligands

    SciTech Connect

    Advanced Light Source; Tian, Guoxin; Rao, Linfeng; Teat, Simon J.; Liu, Guokui

    2009-01-05

    Complexation of U(VI) with N,N,N{prime},N{prime}-tetramethyl-3-oxa-glutaramide (TMOGA) and N,N-dimethyl-3-oxa-glutaramic acid (DMOGA) was studied in comparison with their dicarboxylate analog, oxydiacetic acid (ODA). Thermodynamic parameters, including stability constants, enthalpy and entropy of complexation, were determined by spectrophotometry, potentiometry and calorimetry. Single-crystal X-ray diffractometry, EXAFS spectroscopy, FT-IR absorption and laser-induced luminescence spectroscopy were used to obtain structural information on the U(VI) complexes. Like ODA, TMOGA and DMOGA form tridentate U(VI) complexes, with three oxygen atoms (the amide, ether and/or carboxylate oxygen) coordinating to the linear UO{sub 2}{sup 2+} cation via the equatorial plane. The stability constants, enthalpy and entropy of complexation all decrease in the order ODA > DMOGA > TMOGA, showing that the complexation is entropy driven and the substitution of a carboxylate group with an amide group reduces the strength of complexation with U(VI) due to the decrease in the entropy of complexation. The trend in the thermodynamic stability of the complexes correlates very well with the structural and spectroscopic data obtained by single crystal XRD, FT-IR and laser-induced luminescence spectroscopy.

  5. Subzero-temperature stabilization and spectroscopic characterization of homogeneous oxyferrous complexes of the cytochrome P450 BM3 (CYP102) oxygenase domain and holoenzyme

    SciTech Connect

    Perera, Roshan; Sono, Masanori; Raner, Gregory M.; Dawson, John H. . E-mail: dawson@sc.edu

    2005-12-09

    We describe herein for the first time the formation and spectroscopic characterization of homogeneous oxyferrous complexes of the cytochrome P450 BM3 (CYP102) holoenzyme and heme domain (BMP) at -55 {sup o}C using a 70/30 (v/v) glycerol/buffer cryosolvent. The choice of buffer is a crucial factor with Tris [tris(hydroxymethyl)aminomethane] buffer being significantly more effective than phosphate. The oxyferrous complexes have been characterized with magnetic circular dichroism spectroscopy and the resulting spectra compared to those of the more well-characterized oxyferrous cytochrome P450-CAM. The formation of a stable substrate-bound oxyferrous CYP BM3 holoenzyme, despite the fact that it has the necessary reducing equivalents for turnover, indicates that electron transfer from the flavin domain to the oxyferrous center is very slow at this temperature. The ability to prepare stable homogeneous oxyferrous derivatives of both BMP and the CYP BM3 holoenzyme will enable these species to be used as starting materials for mechanistic investigation of dioxygen activation.

  6. Single molecule spectroscopic characterization of a far-red fluorescent protein (HcRed) from the Anthozoa coral Heteractis crispa

    NASA Astrophysics Data System (ADS)

    Cotlet, Mircea; Habuchi, Satoshi; Whitier, Jennifer E.; Werner, James H.; De Schryver, Frans C.; Hofkens, Johan; Goodwin, Peter M.

    2006-02-01

    We report on the photophysical properties of a far-red intrinsic fluorescent protein by means of single molecule and ensemble spectroscopic methods. The green fluorescent protein (GFP) from Aequorea victoria is a popular fluorescent marker with genetically encoded fluorescence and which can be fused to any biological structure without affecting its function. GFP and its variants provide emission colors from blue to yellowish green. Red intrinsic fluorescent proteins from Anthozoa species represent a recent addition to the emission color palette provided by GFPs. Red intrinsic fluorescent markers are on high demand in protein-protein interaction studies based on fluorescence-resonance energy transfer or in multicolor tracking studies or in cellular investigations where autofluorescence possesses a problem. Here we address the photophysical properties of a far-red fluorescent protein (HcRed), a mutant engineered from a chromoprotein cloned from the sea anemone Heteractis crispa, by using a combination of ensemble and single molecule spectroscopic methods. We show evidence for the presence of HcRed protein as an oligomer and for incomplete maturation of its chromophore. Incomplete maturation results in the presence of an immature (yellow) species absorbing/fluorescing at 490/530-nm. This yellow chromophore is involved in a fast resonance-energy transfer with the mature (purple) chromophore. The mature chromophore of HcRed is found to adopt two conformations, a Transoriented form absorbing and 565-nm and non-fluorescent in solution and a Cis-oriented form absorbing at 590-nm and emitting at 645-nm. These two forms co-exist in solution in thermal equilibrium. Excitation-power dependence fluorescence correlation spectroscopy of HcRed shows evidence for singlet-triplet transitions in the microseconds time scale and for cis-trans isomerization occurring in a time scale of tens of microseconds. Single molecule fluorescence data recorded from immobilized HcRed proteins, all point to the presence of two classes of molecules: proteins with Cis and Trans-oriented chromophores. Immobilization of HcRed in water-filled pores of polyvinyl alcohol leads to a polymer matrix - protein barrel interaction which results in a 'freezing' of the chromophore in a stable conformation for which non-radiative deactivation pathways are either suppressed or reduced. As a result, proteins with both Cis- and Trans-oriented chromophores can be detected at the single molecule level. Polymer chain motion is suggested as a mediator for an eventual cis-trans isomerization of the chromophore in the case of single immobilized proteins.

  7. One-dimensional WO{sub 3} and its hydrate: One-step synthesis, structural and spectroscopic characterization

    SciTech Connect

    Iwu, Kingsley O.; Galeckas, Augustinas; Rauwel, Protima; Kuznetsov, Andrej Y.; Norby, Truls

    2012-01-15

    We report on a one-step hydrothermal growth of one-dimensional (1D) WO{sub 3} nanostructures, using urea as 1D growth-directing agent and a precursor free of metals other than tungsten. By decreasing the pH of the starting solution, the size of the nanostructures was reduced significantly, this development being accompanied by the realization of phase pure hexagonal WO{sub 3} nanorods (elimination of monoclinic impurity phase) and a red shift in optical absorption edge. Surface analyses indicated the presence of reduced tungsten species in the WO{sub 3} nanostructures, which increased two-fold in a hydrated WO{sub 3} phase obtained with further decrease in pH. We suggest that oxygen vacancies are responsible for this defect state in WO{sub 3}, while protons are responsible or contribute significantly to the same in the hydrated phase. - Graphical abstract: The figure illustrates the role of pH in morphological and absorption edge evolution of WO{sub 3} (hydrate) as well as the variation in the concentration of defect electrons between anhydrous and hydrated WO{sub 3}. Highlights: Black-Right-Pointing-Pointer WO{sub 3} nanorods prepared in a one step procedure. Black-Right-Pointing-Pointer HCl (aq) enables phase pure WO{sub 3} nanorods. Black-Right-Pointing-Pointer HCl (aq) induces significant reduction in dimension of and red shift in absorption edge of nanorods. Black-Right-Pointing-Pointer W{sup 5+} detected in hydrothermal WO{sub 3} phase, the concentration of which increases in the hydrated phase. Black-Right-Pointing-Pointer W{sup 5+} from the two phases due to different positive defects.

  8. Characterization of automotive paint clear coats by ultraviolet absorption microspectrophotometry with subsequent chemometric analysis.

    PubMed

    Liszewski, Elisa A; Lewis, Simon W; Siegel, Jay A; Goodpaster, John V

    2010-10-01

    Clear coats have been a staple in automobile paints for almost thirty years and are of forensic interest when comparing transferred and native paints. However, the ultraviolet (UV) absorbers in these paint layers are not typically characterized using UV microspectrophotometry, nor are the results studied using multivariate statistical methods. In this study, measurements were carried out by UV microspectrophotometry on 71 samples from American and Australian automobiles, with subsequent chemometric analysis of the absorbance spectra. Sample preparation proved to be vital in obtaining accurate absorbance spectra and a method involving peeling the clear coat layer and not using a mounting medium was preferred. Agglomerative hierarchical clustering indicated three main groups of spectra, corresponding to spectra with one, two, and three maxima. Principal components analysis confirmed this clustering and the factor loadings indicated that a substantial proportion of the variance in the data set originated from specific spectral regions (230-265 nm, 275-285 nm, and 300-370 nm). The three classes were well differentiated using discriminant analysis, where the cross-validation accuracy was 91.6% and the external validation accuracy was 81.1%. However, results showed no correlation between the make, model, and year of the automobiles. PMID:20925981

  9. Some new [(thione)2Au(diamine)]Cl3 complexes: Synthesis, spectroscopic characterization, computational and in vitro cytotoxic studies

    NASA Astrophysics Data System (ADS)

    Al-Maythalony, Bassem A.; Monim-ul-Mehboob, M.; Altaf, Muhammad; Wazeer, Mohammed I. M.; Isab, Anvarhusein A.; Altuwaijri, Saleh; Ahmed, Ayesha; Dhuna, Vikram; Bhatia, Gaurav; Dhuna, Kshitija; Kamboj, Sukhdev Singh

    2013-11-01

    Recent advances in oncology are focused on developing new complexes of gold(III) with various ligands that show augmented anti-proliferative potential and reduced toxicity as compared to cis-platin. In this study, new Au(III) complexes of the type [(thione)2Au(diamine)]Cl3 are reported, where thione = 1,3-imidazolidine-2-thione (Imt), 1,3-Diazinane-2-thione (Diaz) and diamine = 1,2-diaminoethane (en), 1,3-diaminopropane (pn) or 1,4-diaminobutane (bn). The solid state IR as well as 13C and 15N NMR data indicate that Au(III) center is bonded via sulfur of thiocarbonyl Sdbnd Crbond2 site of the thiones and also chelated by the diamines from the trans side of coordinated thiones. Spectroscopic data are evaluated by comparisons with calculated data from the built and optimized structure by GAUSSIAN 09 at the RB3LYP level with LanL2DZ bases set. These new Au(III) complexes based on mixed thione and diamine ligands are very similar to the square planar structure of tetracoordinate [Au(en)2]Cl3complex. In this study, cytotoxicity data for these gold(III) complexes against C6 glioma cell lines are also reported, and the results indicate some complexes have cytotoxicity comparable to cis-platin.

  10. Molecular structure, spectroscopic characterization of (S)-2-Oxopyrrolidin-1-yl Butanamide and ab initio, DFT based quantum chemical calculations.

    PubMed

    Ramya, T; Gunasekaran, S; Ramkumaar, G R

    2015-10-01

    The experimental and theoretical spectra of (S)-2-Oxopyrrolidin-1-yl Butanamide (S2OPB) were studied. FT-IR and FT-Raman spectra of S2OPB in the solid phase were recorded and analyzed in the range 4000-450 and 5000-50 cm(-1) respectively. The structural and spectroscopic analyses of S2OPB were calculated using ab initio Hartree Fock (HF) and density functional theory calculations (B3PW91, B3LYP) with 6-31G(d,p) basis set. A complete vibrational interpretation has been made on the basis of the calculated Potential Energy Distribution (PED). The HF, B3LYP and B3PW91 methods based NMR calculation has been used to assign the (1)H NMR and (13)C NMR chemical shift of S2OPB. Comparative study on UV-Vis spectral analysis between the experimental and theoretical (B3PW91, B3LYP) methods and the global chemical parameters and local descriptor of reactivity through the Fukui function were performed. Finally the thermodynamic properties of S2OPB were calculated at different temperatures and the corresponding relations between the properties and temperature were also studied. PMID:25956325

  11. [Vermicomposting of different organic materials and three-dimensional excitation emission matrix fluorescence spectroscopic characterization of their dissolved organic matter].

    PubMed

    Yang, Wei; Wang, Dong-sheng; Liu, Man-qiang; Hu, Feng; Li, Hui-xin; Huang, Zhong-yang; Chang, Yi-jun; Jiao, Jia-guo

    2015-10-01

    In this experiment, different proportions of the cattle manure, tea-leaf, herb and mushroom residues, were used as food for earthworm (Eisenia fetida) to study the growth of the earth-worm. Then the characteristics and transformation of nutrient content and three-dimensional excitation emission matrix fluorescence (3DEEM) of dissolved organic matter (DOM) during vermistabilization were investigated by means of chemical and spectroscopic methods. The result showed that the mixture of different ratios of cattle manure with herb residue, and cattle manure with tea-leaf were conducive to the growth of earthworm, while the materials compounded with mushroom residue inhibited the growth of earthworm. With the increasing time of verimcomposting, the pH in vermicompost tended to be circumneutral and weakly acidic, and there were increases in electrical conductivity, and the contents of total nitrogen, total phosphorus, available nitrogen, and available phosphorus, while the total potassium and available potassium increased first and then decreased, and the organic matter content decreased. 3DEEM and fluorescence regional integration results indicated that, the fluorescence of protein-like fluorescence peaks declined significantly, while the intensity of humic-like fluorescence peak increased significantly in DOM. Vermicomposting process might change the compositions of DOM with elevated concentrations of humic acid and fulvic acid in the organics. In all, this study suggested the suitability of 3DEEM for monitoring the organics transformation and assessing the maturity in the vermicomposting. PMID:26995929

  12. Site-directed mutagenesis and spectroscopic characterization of human ferrochelatase: identification of residues coordinating the [2Fe-2S] cluster.

    PubMed

    Crouse, B R; Sellers, V M; Finnegan, M G; Dailey, H A; Johnson, M K

    1996-12-17

    The five cysteines closest to the carboxyl terminus of human ferrochelatase have been individually mutated to serine, histidine, or aspartate residues in an attempt to identify the protein ligands to the [2Fe-2S] cluster. Mutations of cysteines at positions 403, 406, and 411 (C403D, C403H, C406D, C406H, C406S, C411H, and C411S mutants) all resulted in inactive enzyme that failed to assemble the [2Fe-2S] cluster as judged by whole-cell EPR studies. In contrast, mutation of the cysteines at positions 360 and 395 to serines (C360S and C395S mutants) did not affect the enzymatic activity, and the resulting enzyme assembled a [2Fe-2S] cluster that was spectroscopically indistinguishable from the wild-type enzyme. The results indicate that three of the conserved cysteines in the 30-residue C-terminal extension of mammalian ferrochelatase are involved in ligating the [2Fe-2S] cluster. Resonance Raman and variable-temperature magnetic circular dichroism studies of heme-free preparations of human ferrochelatase are reported, and the spectra are best interpreted in terms of one non-cysteinyl, oxygenic ligand for the [2Fe-2S] cluster. Such anomalous coordination could account for the cluster lability compared to similar clusters with complete cysteinyl ligation and hence may be intrinsic to the proposed regulatory role for this cluster in mammalian ferrochelatases. PMID:8973195

  13. Characterization of Copper(II) Interactions with Sinefungin, a Nucleoside Antibiotic: Combined Potentiometric, Spectroscopic and DFT Studies

    PubMed Central

    Jaworska, Maria; Lodowski, Piotr; Mucha, Ariel; Szczepanik, Wojciech; Valensin, Gianni; Cappannelli, Massimo; Je?owska-Bojczuk, Ma?gorzata

    2007-01-01

    Interactions between sinefungin and copper(II) ions were investigated. Stoichiometry and stability constants of the metal-free system and two mononuclear complexes present in solution were determined on the basis of potentiometric data analysis. The results were compared to the Cu(II)-ornithine system due to structural similarities between both molecules. Combined spectroscopic and theoretical studies allowed for determination of coordination pattern for the Cu(II)-sinefungin complexes. At acidic pH, copper is bound in glycine-like coordination mode, identical with that of ornithine. This involves ?-amino group and the carboxyl oxygen. At higher pH, a bis-complex is formed by two sinefungin molecules. The second ligand binds in equatorial position displacing two water molecules, what results in the stable {2N,2O} coordination. Both axial positions are supposed to be occupied by N1 nitrogen donors of adenine moiety, what is confirmed by DFT calculations. They interact indirectly with copper(II) through water molecules as the result of dominant syn conformation of purine. PMID:18273386

  14. Molecular structure, spectroscopic characterization of (S)-2-Oxopyrrolidin-1-yl Butanamide and ab initio, DFT based quantum chemical calculations

    NASA Astrophysics Data System (ADS)

    Ramya, T.; Gunasekaran, S.; Ramkumaar, G. R.

    2015-10-01

    The experimental and theoretical spectra of (S)-2-Oxopyrrolidin-1-yl Butanamide (S2OPB) were studied. FT-IR and FT-Raman spectra of S2OPB in the solid phase were recorded and analyzed in the range 4000-450 and 5000-50 cm-1 respectively. The structural and spectroscopic analyses of S2OPB were calculated using ab initio Hartree Fock (HF) and density functional theory calculations (B3PW91, B3LYP) with 6-31G(d,p) basis set. A complete vibrational interpretation has been made on the basis of the calculated Potential Energy Distribution (PED). The HF, B3LYP and B3PW91 methods based NMR calculation has been used to assign the 1H NMR and 13C NMR chemical shift of S2OPB. Comparative study on UV-Vis spectral analysis between the experimental and theoretical (B3PW91, B3LYP) methods and the global chemical parameters and local descriptor of reactivity through the Fukui function were performed. Finally the thermodynamic properties of S2OPB were calculated at different temperatures and the corresponding relations between the properties and temperature were also studied.

  15. One protein, two chromophores: comparative spectroscopic characterization of 6,7-dimethyl-8-ribityllumazine and riboflavin bound to lumazine protein.

    PubMed

    Paulus, Bernd; Illarionov, Boris; Nohr, Daniel; Roellinger, Guillaume; Kacprzak, Sylwia; Fischer, Markus; Weber, Stefan; Bacher, Adelbert; Schleicher, Erik

    2014-11-20

    We investigated the lumazine protein from Photobacterium leiognathi in complex with its biologically active cofactor, 6,7-dimethyl-8-ribityllumazine, at different redox states and compared the results with samples containing a riboflavin cofactor. Using anaerobic photoreduction, we were able to record optical absorption kinetics from both cofactors in similar protein environments. It could be demonstrated that the protein is able to stabilize a neutral ribolumazine radical with ?35% yield. The ribolumazine radical state was further investigated by W-band continuous-wave EPR and X-band pulsed ENDOR spectroscopy. Here, both the principal values of the g-tensor and an almost complete mapping of the proton hyperfine couplings (hfcs) could be obtained. Remarkably, the g-tensor's principal components are similar to those of the respective riboflavin-containing protein; however, the proton hfcs show noticeable differences. Comparing time-resolved optical absorption and fluorescence data from ribolumazine-containing samples, solely fluorescence but no signs of any intermediate radical or a triplet state could be identified. This is in contrast to lumazine protein samples containing the riboflavin cofactor, for which a high yield of the photogenerated triplet state and some excited flavin radical could be detected using time-resolved spectroscopy. These results clearly demonstrate that ribolumazine is a redox-active molecule and could, in principle, be employed as a cofactor in other enzymatic reactions. PMID:25325849

  16. Monothiol Glutaredoxins Can Bind Linear [Fe3S4]+ and [Fe4S4]2+ Clusters in Addition to [Fe2S2]2+ Clusters: Spectroscopic Characterization and Functional Implications

    PubMed Central

    Zhang, Bo; Bandyopadhyay, Sibali; Shakamuri, Priyanka; Naik, Sunil G.; Huynh, Boi Hanh; Couturier, Jrmy; Rouhier, Nicolas; Johnson, Michael K.

    2013-01-01

    Saccharomyces cerevisiae mitochondrial glutaredoxin 5 (Grx5) is the archetypical member of a ubiquitous class of monothiol glutaredoxins with a strictly conserved CGFS active-site sequence that has been shown to function in biological [Fe2S2]2+ cluster trafficking. In this work, we show that recombinant S. cerevisiae Grx5 purified aerobically after prolonged exposure of the cell-free extract to air or after anaerobic reconstitution in the presence of glutathione, predominantly contains a linear [Fe3S4]+ cluster. The excited state electronic properties and ground state electronic and vibrational properties of the linear [Fe3S4]+ cluster have been characterized using UV-visible absorption/CD/MCD, EPR, Mssbauer and resonance Raman spectroscopies. The results reveal a rhombic S = 5/2 linear [Fe3S4]+ cluster with properties similar to those reported for synthetic linear [Fe3S4]+ clusters and the linear [Fe3S4]+ clusters in purple aconitase. Moreover, the results indicate that the Fe-S cluster content previously reported for many monothiol Grxs has been misinterpreted exclusively in terms of [Fe2S2]2+ clusters, rather than linear [Fe3S4]+ clusters or mixtures of linear [Fe3S4]+ and [Fe2S2]2+ clusters. In the absence of GSH, anaerobic reconstitution of Grx5 yields a dimeric form containing one [Fe4S4]2+ cluster that competent for in vitro activation of apo-aconitase, via intact cluster transfer. The ligation of the linear [Fe3S4]+ and [Fe4S4]2+ clusters in Grx5 has been assessed by spectroscopic, mutational and analytical studies. Potential roles for monothiol Grx5 in scavenging and recycling linear [Fe3S4]+ clusters released during protein unfolding under oxidative stress conditions and in maturation of [Fe4S4]2+ cluster-containing proteins are discussed in light of these results. PMID:24032439

  17. Reactions of Highly Uniform Zeolite H-Supported Rhodium Complexes: Transient Characterization by Infrared and X-ray Absorption Spectroscopies

    SciTech Connect

    Ogino, I.; Gates, B

    2010-01-01

    A zeolite H-{beta}-supported mononuclear rhodium diethene complex (Rh(C{sub 2}H{sub 4}){sub 2}{l_brace}O{sub 2}Al{r_brace}, where the braces indicate a part of the zeolite) was formed by the reaction of Rh(acac)({eta}{sub 2}-C{sub 2}H{sub 4}){sub 2} (acac = acetylacetonate, C{sub 5}H{sub 7}O{sub 2}{sup -}) with the zeolite. Transient characterization of the sample by X-ray absorption near edge structure (XANES) and infrared (IR) spectroscopies (combined with mass spectrometry of the effluent gas) while the sample was in contact with flowing CO indicates a simple stoichiometric conversion of the supported metal complex into another species, identified by the spectra as the zeolite-supported rhodium gem-dicarbonyl (Rh(CO){sub 2}{l_brace}O{sub 2}Al{r_brace}). The sharpness of the v{sub CO} bands in the IR spectrum indicates a high degree of uniformity of the supported rhodium gem-dicarbonyl, and isosbestic points in the XANES spectra as the transformation was occurring imply that the rhodium diethene complex was also highly uniform. Spectra similarly show that treatment of the supported rhodium gem-dicarbonyl with flowing C{sub 2}H{sub 4} resulted in another stoichiometrically simple transformation, giving a species suggested to be Rh(C{sub 2}H{sub 4})(CO){sub 2}{l_brace}O{sub 2}Al{r_brace}. The intermediate was ultimately transformed when the sample was purged with helium into another highly uniform supported species, inferred on the basis of IR spectra to be Rh(C{sub 2}H{sub 4})(CO){l_brace}O{sub 2}Al{r_brace}. Extended X-ray absorption fine structure spectra characterizing the supported rhodium diethene complex and the species formed from it show how the Rh-O bond distance at the Rh-support interface varied in response to the changes in the ligands bonded to the rhodium.

  18. CHARACTERIZATION OF A SAMPLE OF INTERMEDIATE-TYPE AGNs. I. SPECTROSCOPIC PROPERTIES AND SERENDIPITOUS DISCOVERY OF NEW DUAL AGNs

    SciTech Connect

    Benitez, Erika; Cruz-Gonzalez, Irene; Martinez, Benoni; Jimenez-Bailon, Elena; Mendez-Abreu, Jairo; Lopez-Martin, Luis; Fuentes-Carrera, Isaura; Leon-Tavares, Jonathan; Chavushyan, Vahram H.

    2013-01-20

    A sample of 10 nearby intermediate-type active galactic nuclei (AGNs) drawn from the Sloan Digital Sky Survey is presented. The aim of this work is to provide estimations of the black hole (BH) mass for the sample galaxies from the dynamics of the broad-line region. For this purpose, a detailed spectroscopic analysis of the objects was done. Using Baldwin-Phillips-Terlevich diagnostic diagrams, we have carefully classified the objects as true intermediate-type AGNs and found that 80%{sup +7.2%} {sub -17.3%} are composite AGNs. The BH mass estimated for the sample is within 6.54 {+-} 0.16 < log M {sub BH} < 7.81 {+-} 0.14. Profile analysis shows that five objects (J120655.63+501737.1, J121607.08+504930.0, J141238.14+391836.5, J143031.18+524225.8, and J162952.88+242638.3) have narrow double-peaked emission lines in both the red (H{alpha}, [N II] {lambda}{lambda}6548,6583 and [S II] {lambda}{lambda}6716, 6731) and the blue (H{beta} and [O III] {lambda}{lambda}4959, 5007) regions of the spectra, with velocity differences ({Delta}V) between the double peaks within 114 km s{sup -1} < {Delta}V < 256 km s{sup -1}. Two of them, J121607.08+504930.0 and J141238.14+391836.5, are candidates for dual AGNs since their double-peaked emission lines are dominated by AGN activity. In searches of dual AGNs, type 1, type II, and intermediate-type AGNs should be carefully separated, due to the high serendipitous number of narrow double-peaked sources (50% {+-} 14.4%) found in our sample.

  19. Spectroscopic characterization of enzymatic flax retting: Factor analysis of FT-IR and FT-Raman data

    NASA Astrophysics Data System (ADS)

    Archibald, D. D.; Henrikssen, G.; Akin, D. E.; Barton, F. E.

    1998-06-01

    Flax retting is a chemical, microbial or enzymatic process which releases the bast fibers from the stem matrix so they can be suitable for mechanical processing before spinning into linen yarn. This study aims to determine the vibrational spectral features and sampling methods which can be used to evaluate the retting process. Flax stems were retted on a small scale using an enzyme mixture known to yield good retted flax. Processed stems were harvested at various time points in the process and the retting was evaluated by conventional methods including weight loss, color difference and Fried's test, a visual ranking of how the stems disintegrate in hot water. Spectroscopic measurements were performed on either whole stems or powders of the fibers that were mechanically extracted from the stems. Selected regions of spectra were baseline and amplitude corrected using a variant of the multiplicative signal correction method. Principal component regression and partial least-squares regression with full cross-validation were used to determine the spectral features and rate of spectral transformation by regressing the spectra against the retting time in hours. FT-Raman of fiber powders and FT-IR reflectance of whole stems were the simplest and most precise methods for monitoring the retting transformation. Raman tracks the retting by measuring the decrease in aromatic signal and subtle changes in the C-H stretching vibrations. The IR method uses complex spectral features in the fingerprint and carbonyl region, many of which are due to polysaccharide components. Both spectral techniques monitor the retting process with greater precision than the reference method.

  20. Spectroscopic study on the interaction of celecoxib with human carbonic anhydrase II: thermodynamic characterization of the binding process.

    PubMed

    Mehrabi, Masomeh; Ghobadi, Sirous; Khodarahmi, Reza

    2009-12-01

    The effect of celecoxib, a sulfonamide drug, on the structure and function of human carbonic anhydrase II (hCA II) was investigated by various spectroscopic techniques such as UV-Vis, fluorescence and circular dichroism (CD) spectroscopy and differential scanning calorimetry (DSC), in 20 mM Tris, pH 7.75 at 27 degrees C. Kinetic results revealed that celecoxib inhibits the esterase activity of hCA II in a linear competitive manner with K(i) = 61.61 + or -3.05 nM. DSC data indicated that the thermal stability of the enzyme has a minor increment in the presence of celecoxib. Fluorescence measurements showed that the celecoxib acts as a quencher of the enzyme fluorescence and calculation of the protein surface hydrophobicity (PSH), using 1-anilinonaphthalene-8-sulfonate (ANS), revealed the decrement of its PSH upon interaction with the drug. Acrylamide quenching experiments indicated the less accessibility of the tryptophan residues to the acrylamide due to the presence of celecoxib. Stern-Volmer analysis of quenching data at different temperatures elucidated that the quenching of intrinsic fluorescence of hCA II is occurred through a static quenching mechanism. Analysis of the thermodynamic parameters of binding showed that hydrogen bonding and hydrophobic interactions play the major role in stabilization of the enzyme-drug complex. The Job's plot confirmed the existence of one binding site for celecoxib in hCA II. The far- and near-UV CD experiments indicated that celecoxib causes a little increment in alpha-helicity content of hCA II whereas its flexibility is decreased somewhat upon celecoxib binding. PMID:19879770

  1. Spectroscopic and wet chemical characterization of solid waste organic matter of different age in landfill sites, southern Germany.

    PubMed

    Bumler, Rupert; Kgel-Knabner, Ingrid

    2008-01-01

    Landfill sites are potential sources of hazardous emissions by degradation and transformation processes of waste organic matter. Its chemical composition and microbial degradability are key factors for risk management, after-care, and estimation of potential emissions. The aim of the study is to provide information about composition and extent of transformation of waste organic matter in four landfill sites in Bavaria, Southern Germany by means of (13)C NMR spectroscopy, acid-hydrolyzable carbohydrates, chloroform-methanol extractable lipids, acid-hydrolyzable proteins, and lignin compounds after CuO oxidation. Ten samples of about 20 to 25 yr, 15 to 20 yr, and 5 to 10 yr of deposition each were taken at 2 m depth intervals by grab drilling till 10-m depth. Increasing temperatures from about 15 degrees C at 2-m depth to >40 degrees C at 10-m depth are found at some of the sites, representing optimum conditions for mesophile methane bacteria. Moisture contents of 160 to 310 g kg(-1) (oven dry), however, provide limiting conditions for anaerobic biodecay. Spectroscopic and chemical variables generally indicate a low extent of biodegradation and transformation at all sites despite a considerable heterogeneity of the samples. Independent of the time and depth of deposition more than 50% of the carbohydrate fraction of the waste organic matter provide a high potential for methane emissions and on-site energy production. There was no significant accumulation of long-chain organic and aromatic compounds, and of lignin degradation products even after more than 25 yr of rotting indicating higher extent of decomposition or stabilization of the waste organic matter. Installation of seepage water cleaning and recirculation systems are recommended to increase suboptimal moisture contents with respect to microbial methanogenesis, energy production, and long-term stabilization of municipal solid waste. PMID:18178887

  2. Synthesis, crystal structure, spectroscopic characterization and nonlinear optical properties of manganese (II) complex of picolinate: A combined experimental and computational study

    NASA Astrophysics Data System (ADS)

    Tamer, Ömer; Avcı, Davut; Atalay, Yusuf; Çoşut, Bünyemin; Zorlu, Yunus; Erkovan, Mustafa; Yerli, Yusuf

    2016-02-01

    A novel manganese (II) complex with picolinic acid (pyridine 2-carboxylic acid, Hpic), namely, [Mn(pic)2(H2O)2] was prepared and its crystal structure was fully characterized by using single crystal X-ray diffraction. Picolinate (pic) ligands were coordinated to the central manganese(II) ion as bidentate N,O-donors through the nitrogen atoms of pyridine rings and the oxygen atoms of carboxylate groups forming five-membered chelate rings. The spectroscopic characterization of Mn(II) complex was performed by the applications of FT-IR, Raman, UV-vis and EPR techniques. In order to support these studies, density functional theory (DFT) calculations were carried out by using B3LYP level. IR and Raman spectra were simulated at B3LYP level, and obtained results indicated that DFT calculations generally give compatible results to the experimental ones. The electronic structure of the Mn(II) complex was predicted using time dependent DFT (TD-DFT) method with polarizable continuum model (PCM). Molecular stability, hyperconjugative interactions, intramolecular charge transfer (ICT) and bond strength were investigated by applying natural bond orbital (NBO) analysis. Nonlinear optical properties of Mn(II) complex were investigated by the determining of molecular polarizability (α) and hyperpolarizability (β) parameters.

  3. Fingerprints of polycyclic aromatic hydrocarbons (PAHs) in infrared absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Tommasini, Matteo; Lucotti, Andrea; Alfè, Michela; Ciajolo, Anna; Zerbi, Giuseppe

    2016-01-01

    We have analyzed a set of 51 PAHs whose structures have been hypothesized from mass spectrometry data collected on samples extracted from carbon particles of combustion origin. We have obtained relationships between infrared absorption signals in the fingerprint region (mid-IR) and the chemical structures of PAHs, thus proving the potential of IR spectroscopy for the characterization of the molecular structure of aromatic combustion products. The results obtained here for the spectroscopic characterization of PAHs can be also of interest in Materials Science and Astrophysics.

  4. Fingerprints of polycyclic aromatic hydrocarbons (PAHs) in infrared absorption spectroscopy.

    PubMed

    Tommasini, Matteo; Lucotti, Andrea; Alfè, Michela; Ciajolo, Anna; Zerbi, Giuseppe

    2016-01-01

    We have analyzed a set of 51 PAHs whose structures have been hypothesized from mass spectrometry data collected on samples extracted from carbon particles of combustion origin. We have obtained relationships between infrared absorption signals in the fingerprint region (mid-IR) and the chemical structures of PAHs, thus proving the potential of IR spectroscopy for the characterization of the molecular structure of aromatic combustion products. The results obtained here for the spectroscopic characterization of PAHs can be also of interest in Materials Science and Astrophysics. PMID:26208268

  5. Characterization of biochar-derived dissolved organic matter using UV-visible absorption and excitation-emission fluorescence spectroscopies.

    PubMed

    Jamieson, Tyler; Sager, Eric; Guguen, Cline

    2014-05-01

    In recent years, biochar has become of considerable interest for a variety of environmental applications. However, the feasibility of its application is entirely dependent on its physical and chemical properties, including the characteristics of biochar-derived dissolved organic matter (DOM). The goal of this study was to assess the use of optical analysis for the purpose of characterizing biochar-derived DOM. Three different biochars (slow pyrolysis birch and maple; fast pyrolysis maple) were produced and leached in distilled water over 17d. Samples were taken on days 3, 10, 13 and 17, filtered, and analyzed for DOC content. Samples were also subjected to optical analysis using UV-visible absorption and excitation-emission matrix (EEM) fluorescence spectroscopies. EEM fluorescence data were further analyzed using parallel factor analysis (PARAFAC). Absorbance and fluorescence results were combined and examined using principal component analysis (PCA). Significant differences in the water soluble organic carbon content were observed for all biochar types. The estimated aromaticity (SUVA254) and mean molecular weight (S275-295) of biochar-derived DOM were also found to differ based on biochar type. PARAFAC analysis identified three humic-like components and one protein-like component. Distinct DOM signatures were observed for each biochar type. Transformations in biochar DOM characteristics over time were also observed. The PCA showed a clear delineation in biochar types based on their optical properties. The results of this study indicate that optical analysis may provide valuable information regarding the characteristics of biochar-derived DOM. PMID:24359913

  6. Macroscopic and spectroscopic Characterization of Selenate, Selenite, and Chromate Adsorption at the SolidWater Interface of -Al2O3

    SciTech Connect

    Elzinga, E.; Tang, Y; McDonald, J; DeSisto, S; Reeder, R

    2009-01-01

    The interaction of selenate, selenite, and chromate with the hydrated surface of {gamma}-Al{sub 2}O{sub 3} was studied using a combination of macroscopic pH edge data, electrophoretic mobility measurements, and X-ray absorption spectroscopic analyses. The pH edge data show generally increased oxyanion adsorption with decreasing pH, and indicate ionic strength-(in)dependent adsorption of chromate and selenate across the pH range 4-9, and ionic strength-(in)dependent adsorption of selenite in this pH range. The adsorption of chromate peaks at pH 5.0, whereas for selenate and selenite no pH adsorption maxima are observed. Electrophoretic mobility measurements show that all three oxyanions decrease the zeta potential of {gamma}-Al{sub 2}O{sub 3} upon adsorption; however, only selenite decreased the pHPZC of the {gamma}-Al{sub 2}O{sub 3} sorbent. EXAFS data indicate that selenite ions are coordinated in a bridging bidentate fashion to surface AlO6 octahedra, whereas no second-neighbor Al scattering was observed for adsorbed selenate ions. Combined, the results presented here show that pH is a major factor in determining the extent of adsorption of selenate, selenite, and chromate on hydrated {gamma}-Al{sub 2}O{sub 3}. The results point to substantial differences between these anions as to the mode of adsorption at the hydrated {gamma}-Al{sub 2}O{sub 3} surface, with selenate adsorbing as nonprotonated outer-sphere complexes, chromate forming a mixture of monoprotonated and nonprotonated outer-sphere adsorption complexes, and selenite coordinating as inner-sphere surface complexes in bridging configuration.

  7. Portuguese tin-glazed earthenware from the 17th century. Part 2: A spectroscopic characterization of pigments, glazes and pastes of the three main production centers.

    PubMed

    Vieira Ferreira, L F; Ferreira, D P; Conceição, D S; Santos, L F; Pereira, M F C; Casimiro, T M; Ferreira Machado, I

    2015-10-01

    Sherds representative of the three Portuguese faience production centers of the 17th century - Lisbon, Coimbra and Vila Nova were studied with the use of mostly non-invasive spectroscopies, namely: ground state diffuse reflectance absorption (GSDR), micro-Raman, Fourier-transform infrared (FT-IR) and proton induced X-ray (PIXE) or X-ray fluorescence emission (XRF). X-ray diffraction (XRD) experiments were also performed. The obtained results evidence a clear similarity in the pastes of the pottery produced Vila Nova and some of the ceramic pastes from Lisbon, in accordance with documental sources that described the use of Lisbon clays by Vila Nova potters, at least since mid 17th century. Quartz and Gehlenite are the main components of the Lisbon's pastes, but differences between the ceramic pastes were detected pointing out to the use of several clay sources. The spectroscopic trend exhibited Coimbra's pottery is remarkably different, Quartz and Diopside being the major components of these pastes, enabling one to well define a pattern for these ceramic bodies. The blue pigment from the Lisbon samples is a cobalt oxide that exists in the silicate glassy matrix, which enables the formation of detectable cobalt silicate microcrystals in most productions of the second half of the 17th century. No micro-Raman cobalt blue signature could be detected in the Vila Nova and Coimbra blue glazes. This is in accordance with the lower kiln temperatures in these two production centers and with Co(2+) ions dispersed in the silicate matrix. In all cases the white glaze is obtained with the use of tin oxide. Hausmannite was detected as the manganese oxide mineral used to produce the purple glaze (wine color "vinoso") in Lisbon. PMID:25965511

  8. Spectroscopic Characterization of a Multiband Complex Oxide: Insulating and Conducting Cement 12CaO7Al?O?

    SciTech Connect

    McLeod, John A.; Buling, A.; Kurmaev, Ernst Z.; Sushko, Petr V.; Neumann, N.; Finkelstein, L. D.; Kim, S. W.; Hosono, H.; Moewes, Alexander

    2012-01-13

    Natural 12CaO7Al?O? (C12A7) is a wide band gap insulator, but conductivity can be realized by introducing oxygen deficiency. Currently, there are two competing models explaining conductivity in oxygen-deficient C12A7, one involving the electron transfer via a cage conduction band inside the nominal band gap, the other involving electron hopping along framework lattice sites. To help resolve this debate, we probe insulating and conducting C12A7 with x-ray emission, x-ray absorption, and x-ray photoemission spectroscopy, which provide a full picture of both the valence and conduction band edges in these materials. Thesemeasurements suggest the existence of a narrow conduction band between themain conduction and valence bands common in both conducting and insulating C12A7 and support the theory that free electrons in oxygen-deficient C12A7 occupy the low-energy states of this narrow band. Our measurements are corroborated with density functional theory calculations.

  9. Luminescence and advanced mass spectroscopic characterization of sodium zinc orthophosphate phosphor for low-cost light-emitting diodes.

    PubMed

    Mishra, Savvi; Swati, G; Rajesh, B; Tyagi, Kriti; Gahtori, Bhasker; Sivaiah, B; Vijayan, N; Dalai, M K; Dhar, A; Auluck, S; Jayasimhadri, M; Haranath, D

    2016-03-01

    A new rare-earth-free NaZnPO4 :Mn(2+) (NZP:Mn) phosphor powder has been developed by our group and investigated meticulously for the first time using secondary ion mass spectroscopy and chemical imaging techniques. The studies confirmed the effective incorporation of Mn(2+) into the host lattice, resulting in an enhancement of photoluminescence intensity. Phase purity has been verified and structure parameters have been determined successfully by Rietveld refinement studies. The NZP:Mn phosphor powder exhibits strong absorption bands in the ultraviolet and visible (300-470 nm) regions with a significant broad yellow-green (~543 nm) emission due to the characteristic spin forbidden d-d transition ((4) T1 →(6) A1 ) of Mn(2+) ions, indicating weak crystal field strength at the zinc-replaced manganese site. The decay constants are a few milliseconds, which is a pre-requisite for applications in many display devices. The results obtained suggest that this new phosphor powder will find many interesting applications in semiconductor physics, as cost-effective light-emitting diodes (LEDs), as solar cells and in photo-physics. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26198805

  10. Spectroscopic detection

    DOEpatents

    Woskov, Paul P. (Bedford, MA); Hadidi, Kamal (Cambridge, MA)

    2003-01-01

    In embodiments, spectroscopic monitor monitors modulated light signals to detect low levels