Carbon doped lanthanum aluminate (LaAlO3:C) synthesized by solid state reaction for application in UV thermoluminescent dosimetry

International Nuclear Information System (INIS)

Alves, N.

2015-01-01

In this work we discuss the TL output for LaAlO 3 :C crystals grown by using three different combinations of Al 2 O 3 , La 2 O 3 and carbon atoms during the synthesis process. Recently, LaAlO 3 single crystals, co-doped with Ce 3+ and Dy 3+ rare earth trivalent ions and grown under hydrothermal conditions, have been reported to show high thermoluminescent response (TL) when exposed to low levels of ultraviolet radiation (UVR). However, undoped LaAlO 3 synthesized by solid state reaction method from the 1:1 mixture of aluminum and lanthanum oxide under reducing atmosphere revealed to have still higher thermoluminescent sensitivity to UV photon fields than the co-doped with Ce 3+ and Dy 3+ . It is well known that carbon doped aluminum oxide monocrystals have excellent TL and photoluminescent response properties for X-rays, UV and gamma radiation fields. Thus, we conducted three different syntheses of LaAlO 3 by this solid state reaction method, doping the mixture with carbon. The lanthanum aluminate polycrystals were synthesized from the 1:1 mixture of aluminum and lanthanum oxide, adding 0.1wt.% carbon and annealed at 1700°C for two hours in hydrogen atmosphere. The X-ray diffraction analysis revealed the formation of rhombohedral LaAlO 3 crystallographic phase, however a small percentage (15%) of Al 2 O 3 has been also identified. The UV-Vis absorbance spectra were obtained and F and F + - center were ascribed. The UV irradiations were carried out using a commercial 8W UV lamp. Thermoluminescence measurements were performed at a Harshaw 4500 TL reader. All compositions investigated have shown high TL sensitivity to UVR. (author)

Importance of Vibronic Effects in the UV-Vis Spectrum of the 7,7,8,8-Tetracyanoquinodimethane Anion.

Science.gov (United States)

Tapavicza, Enrico; Furche, Filipp; Sundholm, Dage

2016-10-11

We present a computational method for simulating vibronic absorption spectra in the ultraviolet-visible (UV-vis) range and apply it to the 7,7,8,8-tetracyanoquinodimethane anion (TCNQ - ), which has been used as a ligand in black absorbers. Gaussian broadening of vertical electronic excitation energies of TCNQ - from linear-response time-dependent density functional theory produces only one band, which is qualitatively incorrect. Thus, the harmonic vibrational modes of the two lowest doublet states were computed, and the vibronic UV-vis spectrum was simulated using the displaced harmonic oscillator approximation, the frequency-shifted harmonic oscillator approximation, and the full Duschinsky formalism. An efficient real-time generating function method was implemented to avoid the exponential complexity of conventional Franck-Condon approaches to vibronic spectra. The obtained UV-vis spectra for TCNQ - agree well with experiment; the Duschinsky rotation is found to have only a minor effect on the spectrum. Born-Oppenheimer molecular dynamics simulations combined with calculations of the electronic excitation energies for a large number of molecular structures were also used for simulating the UV-vis spectrum. The Born-Oppenheimer molecular dynamics simulations yield a broadening of the energetically lowest peak in the absorption spectrum, but additional vibrational bands present in the experimental and simulated quantum harmonic oscillator spectra are not observed in the molecular dynamics simulations. Our results underline the importance of vibronic effects for the UV-vis spectrum of TCNQ - , and they establish an efficient method for obtaining vibronic spectra using a combination of linear-response time-dependent density functional theory and a real-time generating function approach.

Spectral Estimation of UV-Vis Absorbance Time Series for Water Quality Monitoring

Directory of Open Access Journals (Sweden)

Leonardo Plazas-Nossa

2017-05-01

Full Text Available Context: Signals recorded as multivariate time series by UV-Vis absorbance captors installed in urban sewer systems, can be non-stationary, yielding complications in the analysis of water quality monitoring. This work proposes to perform spectral estimation using the Box-Cox transformation and differentiation in order to obtain stationary multivariate time series in a wide sense. Additionally, Principal Component Analysis (PCA is applied to reduce their dimensionality. Method: Three different UV-Vis absorbance time series for different Colombian locations were studied: (i El-Salitre Wastewater Treatment Plant (WWTP in Bogotá; (ii Gibraltar Pumping Station (GPS in Bogotá; and (iii San-Fernando WWTP in Itagüí. Each UV-Vis absorbance time series had equal sample number (5705. The esti-mation of the spectral power density is obtained using the average of modified periodograms with rectangular window and an overlap of 50%, with the 20 most important harmonics from the Discrete Fourier Transform (DFT and Inverse Fast Fourier Transform (IFFT. Results: Absorbance time series dimensionality reduction using PCA, resulted in 6, 8 and 7 principal components for each study site respectively, altogether explaining more than 97% of their variability. Values of differences below 30% for the UV range were obtained for the three study sites, while for the visible range the maximum differences obtained were: (i 35% for El-Salitre WWTP; (ii 61% for GPS; and (iii 75% for San-Fernando WWTP. Conclusions: The Box-Cox transformation and the differentiation process applied to the UV-Vis absorbance time series for the study sites (El-Salitre, GPS and San-Fernando, allowed to reduce variance and to eliminate ten-dency of the time series. A pre-processing of UV-Vis absorbance time series is recommended to detect and remove outliers and then apply the proposed process for spectral estimation. Language: Spanish.

UV-VIS absorption spectroscopy: Lambert-Beer reloaded

Science.gov (United States)

Mäntele, Werner; Deniz, Erhan

2017-02-01

UV-VIS absorption spectroscopy is used in almost every spectroscopy laboratory for routine analysis or research. All spectroscopists rely on the Lambert-Beer Law but many of them are less aware of its limitations. This tutorial discusses typical problems in routine spectroscopy that come along with technical limitations or careless selection of experimental parameters. Simple rules are provided to avoid these problems.

TROPOMI and TROPI: UV/VIS/NIR/SWIR instruments

NARCIS (Netherlands)

Levelt, P.F.; Oord, G.H.J. van den; Dobber, M.; Eskes, H.; Weele, M. van; Veefkind, P.; Oss, R. van; Aben, I.; Jongma, R.T.; Landgraf, J.; Vries, J. de; Visser, H.

2006-01-01

TROPOMI (Tropospheric Ozone-Monitoring Instrument) is a five-channel UV-VIS-NIR-SWIR non-scanning nadir viewing imaging spectrometer that combines a wide swath (114°) with high spatial resolution (10 × 10 km 2). The instrument heritage consists of GOME on ERS-2, SCIAMACHY on Envisat and, especially,

The UV-VIS spectrophotometry applied to color and stability study in colored mortars

Directory of Open Access Journals (Sweden)

Alejandre, F. J.

1999-06-01

Full Text Available In the field of methodologies for color studying, a research of it has been done on colored mortars by applying uv-vis spectrophotometry, instrumental technique which can be used for solid materials works, and previously applied to building materials study. Results obtained show that the mentioned technique permits to evaluate quantitatively and qualitatively colors in an easy and objective way, besides nowadays advantages of the instrumental analysis: digital color register, computerized data processing, and precision and exactness increment in chromatic comparisons.

Dentro de las metodologías existentes para el estudio del color, se ha realizado una investigación del mismo en morteros coloreados por medio de la espectrofotometría UV-VIS, técnica instrumental que es adaptable al trabajo con materiales sólidos, y que ha sido aplicada anteriormente en el estudio de diversos materiales de construcción. Los resultados obtenidos muestran cómo la citada técnica permite además de evaluar cualitativamente y cuantitativamente los colores de forma sencilla y objetiva, el disponer de las ventajas que conlleva actualmente el análisis instrumental: registro digital del color, tratamiento informatizado de datos y aumento de precisión y exactitud en las comparaciones cromáticas.

Carbon doped lanthanum aluminate (LaAlO3:C) UV thermoluminescent properties synthesized by solid state reaction with three different mixing methodologies

International Nuclear Information System (INIS)

Alves, N.

2017-01-01

In this work we discuss the thermoluminescent (TL) response for LaAlO 3 :C crystals grown by using three different combinations of Al 2 O 3 , La 2 O 3 and carbon atoms during the synthesis process. Recently, LaAlO 3 single crystals, co-doped with Ce 3+ and Dy 3+ rare earth trivalent ions and grown under hydrothermal conditions, have been reported to show high thermoluminescent response (TL) when exposed to low levels of ultraviolet radiation (UVR). However, undoped LaAlO 3 synthesized by solid state reaction method from the 1:1 mixture of aluminum and lanthanum oxide under reducing atmosphere revealed to have still higher thermoluminescent sensitivity to UV photon fields than the co-doped with Ce 3+ and Dy 3+ . It is well known that carbon doped aluminum oxide monocrystals have excellent TL and photoluminescent response properties for X-rays, UV and gamma radiation fields. Thus, we conducted three different syntheses of LaAlO 3 by the solid state reaction method, doping the mixture with carbon. The lanthanum aluminate polycrystals were synthesized from the 1:1 mixture of aluminum and lanthanum oxide, adding 0.1wt.% carbon and annealed at 1700°C for two hours in hydrogen atmosphere. The X-ray diffraction analysis revealed the formation of rhombohedral LaAlO 3 crystallographic phase, however a small percentage (15%) of Al 2 O 3 has been also identified. The UV-Vis absorbance spectra were obtained and F and F + - center were ascribed. The UV irradiations were carried out using a commercial 8W UV lamp. Thermoluminescence measurements were performed at a Harshaw 4500 TL reader. All compositions investigated have shown high TL sensitivity to UVR. (author)

Electrochromic characteristics of a nickel borate thin film investigated by in situ XAFS and UV/vis spectroscopy

International Nuclear Information System (INIS)

Yoshida, Masaaki; Iida, Tsuyoshi; Mineo, Takehiro

2014-01-01

The electrochromic transition of a nickel borate thin film between colorless and brown was examined by means of in situ XAFS and UV/vis spectroscopy. The XAFS spectra showed that the average valence state of the nickel species in the film changed from +2.1 to +3.8 following the application of an electrode potential. Additionally, a broad peak at 700 nm was observed during in situ UV/vis absorption measurements on the application of a positive potential. These results suggest that the nickel borate film reversibly forms a NiOOH structure with a domain size of several nanometers during the electrochromic reaction. (author)

Applications of derivative UV/VIS spectroscopy in water analysis

International Nuclear Information System (INIS)

Hellmann, H.

1994-01-01

Derivative UV/VIS spectra offer new possibilities in determination and identification of trace substances in waters, suspended matter, and in sediments. Aromatics and their derivatives, such as alkyl-benzene-sulfonates, esters of phthalic acid, alkyl-phenol-oxethylates etc., but also non-aromatic substances with a π-bond can be identified. Compounds showing no absorption in the UV/VIS range can be detected by adding a suitable corectant, e.g. cationic detergents by means of disulfin-blue of BiJ 4 - . Normally, a clean-up is necessary. The recommended procedure is two- or multi-stage chromatography on adsorbing layers of silica gel or aluminium oxide. Thus, numerous substances can be identified and quantified at levels as low as 5 microgram. In some cases, it will be useful to supplement the method by fluorescent spectra of higher orders. (orig.) [de

The Classification of Ground Roasted Decaffeinated Coffee Using UV-VIS Spectroscopy and SIMCA Method

Science.gov (United States)

Yulia, M.; Asnaning, A. R.; Suhandy, D.

2018-05-01

In this work, an investigation on the classification between decaffeinated and non- decaffeinated coffee samples using UV-VIS spectroscopy and SIMCA method was investigated. Total 200 samples of ground roasted coffee were used (100 samples for decaffeinated coffee and 100 samples for non-decaffeinated coffee). After extraction and dilution, the spectra of coffee samples solution were acquired using a UV-VIS spectrometer (Genesys™ 10S UV-VIS, Thermo Scientific, USA) in the range of 190-1100 nm. The multivariate analyses of the spectra were performed using principal component analysis (PCA) and soft independent modeling of class analogy (SIMCA). The SIMCA model showed that the classification between decaffeinated and non-decaffeinated coffee samples was detected with 100% sensitivity and specificity.

High Energy, Single-Mode, All-Solid-State and Tunable UV Laser Transmitter

Science.gov (United States)

Prasad, Narasimha S.; Singh, Upendra N.; Hovis, FLoyd

2007-01-01

A high energy, single mode, all solid-state Nd:YAG laser primarily for pumping an UV converter is developed. Greater than 1 J/pulse at 50 HZ PRF and pulse widths around 22 ns have been demonstrated. Higher energy, greater efficiency may be possible. Refinements are known and practical to implement. Technology Demonstration of a highly efficient, high-pulse-energy, single mode UV wavelength generation using flash lamp pumped laser has been achieved. Greater than 90% pump depletion is observed. 190 mJ extra-cavity SFG; IR to UV efficiency > 21% (> 27% for 1 mJ seed). 160 mJ intra-cavity SFG; IR to UV efficiency up to 24% Fluence laser is being refined to match or exceed the above UV converter results. Currently the Nd:YAG pump laser development is a technology demonstration. System can be engineered for compact packaging.

Carbon doped lanthanum aluminate (LaAlO{sub 3}:C) UV thermoluminescent properties synthesized by solid state reaction with three different mixing methodologies

Energy Technology Data Exchange (ETDEWEB)

Alves, N., E-mail: neire.radiologia@yahoo.com.br, E-mail: farialo@cdtn.br [Universidade Federal do Estado de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear; Ferraz, W.B.; Faria, L.O., E-mail: ferrazw@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

2017-07-01

In this work we discuss the thermoluminescent (TL) response for LaAlO{sub 3}:C crystals grown by using three different combinations of Al{sub 2}O{sub 3}, La{sub 2}O{sub 3} and carbon atoms during the synthesis process. Recently, LaAlO{sub 3} single crystals, co-doped with Ce{sup 3+} and Dy{sup 3+} rare earth trivalent ions and grown under hydrothermal conditions, have been reported to show high thermoluminescent response (TL) when exposed to low levels of ultraviolet radiation (UVR). However, undoped LaAlO{sub 3} synthesized by solid state reaction method from the 1:1 mixture of aluminum and lanthanum oxide under reducing atmosphere revealed to have still higher thermoluminescent sensitivity to UV photon fields than the co-doped with Ce{sup 3+} and Dy{sup 3+}. It is well known that carbon doped aluminum oxide monocrystals have excellent TL and photoluminescent response properties for X-rays, UV and gamma radiation fields. Thus, we conducted three different syntheses of LaAlO{sub 3} by the solid state reaction method, doping the mixture with carbon. The lanthanum aluminate polycrystals were synthesized from the 1:1 mixture of aluminum and lanthanum oxide, adding 0.1wt.% carbon and annealed at 1700°C for two hours in hydrogen atmosphere. The X-ray diffraction analysis revealed the formation of rhombohedral LaAlO{sub 3} crystallographic phase, however a small percentage (15%) of Al{sub 2}O{sub 3} has been also identified. The UV-Vis absorbance spectra were obtained and F and F{sup +}- center were ascribed. The UV irradiations were carried out using a commercial 8W UV lamp. Thermoluminescence measurements were performed at a Harshaw 4500 TL reader. All compositions investigated have shown high TL sensitivity to UVR. (author)

Estimation of water quality by UV/Vis spectrometry in the framework of treated wastewater reuse.

Science.gov (United States)

Carré, Erwan; Pérot, Jean; Jauzein, Vincent; Lin, Liming; Lopez-Ferber, Miguel

2017-07-01

The aim of this study is to investigate the potential of ultraviolet/visible (UV/Vis) spectrometry as a complementary method for routine monitoring of reclaimed water production. Robustness of the models and compliance of their sensitivity with current quality limits are investigated. The following indicators are studied: total suspended solids (TSS), turbidity, chemical oxygen demand (COD) and nitrate. Partial least squares regression (PLSR) is used to find linear correlations between absorbances and indicators of interest. Artificial samples are made by simulating a sludge leak on the wastewater treatment plant and added to the original dataset, then divided into calibration and prediction datasets. The models are built on the calibration set, and then tested on the prediction set. The best models are developed with: PLSR for COD (R pred 2 = 0.80), TSS (R pred 2 = 0.86) and turbidity (R pred 2 = 0.96), and with a simple linear regression from absorbance at 208 nm (R pred 2 = 0.95) for nitrate concentration. The input of artificial data significantly enhances the robustness of the models. The sensitivity of the UV/Vis spectrometry monitoring system developed is compatible with quality requirements of reclaimed water production processes.

Solid-State Synthesis and Photocatalytic Activity of Polyterthiophene Derivatives/TiO2 Nanocomposites

Directory of Open Access Journals (Sweden)

Ruxangul Jamal

2014-05-01

Full Text Available Poly(3,4-propylenedioxy-2,2':5',2"-terthiophene/TiO2 and poly(3,4-(2,2-dimethylenepropylenedioxy-2,2':5',2"-terthiophene/TiO2 nanocomposites were synthesized by a simple solid-state method. Additionally, the poly(3,4-propylenedioxy thiophene/TiO2 and poly(3,4-2,2-dimethylenepropylenedioxythiophene/TiO2 nanocomposites were synthesized in a similar manner for comparison. The structure and morphology were characterized by Fourier transform infrared (FTIR, ultraviolet-visible (UV-Vis absorption spectroscopy, X-ray diffraction (XRD and transmission electron microscopy (TEM. The photocatalytic activities of the nanocomposites were examined through the degradation processes of a methylene blue (MB solution under UV light and sunlight irradiation. The results of FTIR and UV-Vis spectra showed that the composites were successfully synthesized by solid-state method and the poly(3,4-propylenedioxy-2,2':5',2"-terthiophene/TiO2 and poly(3,4-(2,2-dimethylenepropylenedioxy-2,2':5',2"-terthiophene/TiO2 nanocomposite had a higher oxidation degree and conjugation length than others. The results also indicated that the TiO2 had no effect on the crystallinity of composites, but was well embedded in the polymer matrix. Additionally, the highest degradation efficiency of 90.5% occurred in the case of the poly(3,4-propylenedioxy-2,2':5',2"-terthiophene/TiO2 nanocomposite.

Sequential capillary electrophoresis analysis using optically gated sample injection and UV/vis detection.

Science.gov (United States)

Liu, Xiaoxia; Tian, Miaomiao; Camara, Mohamed Amara; Guo, Liping; Yang, Li

2015-10-01

We present sequential CE analysis of amino acids and L-asparaginase-catalyzed enzyme reaction, by combing the on-line derivatization, optically gated (OG) injection and commercial-available UV-Vis detection. Various experimental conditions for sequential OG-UV/vis CE analysis were investigated and optimized by analyzing a standard mixture of amino acids. High reproducibility of the sequential CE analysis was demonstrated with RSD values (n = 20) of 2.23, 2.57, and 0.70% for peak heights, peak areas, and migration times, respectively, and the LOD of 5.0 μM (for asparagine) and 2.0 μM (for aspartic acid) were obtained. With the application of the OG-UV/vis CE analysis, sequential online CE enzyme assay of L-asparaginase-catalyzed enzyme reaction was carried out by automatically and continuously monitoring the substrate consumption and the product formation every 12 s from the beginning to the end of the reaction. The Michaelis constants for the reaction were obtained and were found to be in good agreement with the results of traditional off-line enzyme assays. The study demonstrated the feasibility and reliability of integrating the OG injection with UV/vis detection for sequential online CE analysis, which could be of potential value for online monitoring various chemical reaction and bioprocesses. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

UV/Vis visible optical waveguides fabricated using organic-inorganic nanocomposite layers.

Science.gov (United States)

Simone, Giuseppina; Perozziello, Gerardo

2011-03-01

Nanocomposite layers based on silica nanoparticles and a methacrylate matrix are synthesized by a solvent-free process and characterized in order to realize UV/Vis transparent optical waveguides. Chemical functionalization of the silica nanoparticles permits to interface the polymers and the silica. The refractive index, roughness and wettability and the machinability of the layers can be tuned changing the silica nanoparticle concentration and chemical modification of the surface of the nanoparticles. The optical transparency of the layers is affected by the nanoparticles organization between the organic chains, while it increased proportionally with respect to silica concentration. Nanocomposite layers with a concentration of 40 wt% in silica reached UV transparency for a wavelength of 250 nm. UV/Vis transparent waveguides were micromilled through nanocomposite layers and characterized. Propagation losses were measured to be around 1 dB cm(-1) at a wavelength of 350 nm.

NIR-Vis-UV Light-Responsive Actuator Films of Polymer-Dispersed Liquid Crystal/Graphene Oxide Nanocomposites.

Science.gov (United States)

Cheng, Zhangxiang; Wang, Tianjie; Li, Xiao; Zhang, Yihe; Yu, Haifeng

2015-12-16

To take full advantage of sunlight for photomechanical materials, NIR-vis-UV light-responsive actuator films of polymer-dispersed liquid crystal (PDLC)/graphene oxide (GO) nanocomposites were fabricated. The strategy is based on phase transition of LCs from nematic to isotropic phase induced by combination of photochemical and photothermal processes in the PDLC/GO nanocomposites. Upon mechanical stretching of the film, both topological shape change and mesogenic alignment occurred in the separated LC domains, enabling the film to respond to NIR-vis-UV light. The homodispersed GO flakes act as photoabsorbent and nanoscale heat source to transfer NIR or VIS light into thermal energy, heating the film and photothermally inducing phase transition of LC microdomains. By utilizing photochemical phase transition of LCs upon UV-light irradiation, one azobenzene dye was incorporated into the LC domains, endowing the nanocomposite films with UV-responsive property. Moreover, the light-responsive behaviors can be well-controlled by adjusting the elongation ratio upon mechanical treatment. The NIR-vis-UV light-responsive PDLC/GO nanocomposite films exhibit excellent properties of easy fabrication, low-cost, and good film-forming and mechanical features, promising their numerous applications in the field of soft actuators and optomechanical systems driven directly by sunlight.

Unexpected solvent effects on the UV/Vis absorption spectra of o-cresol in toluene and benzene: in contrast with non-aromatic solvents.

Science.gov (United States)

Zheng, Dong; Yuan, Xiang-Ai; Ma, Haibo; Li, Xiaoxiong; Wang, Xizhang; Liu, Ziteng; Ma, Jing

2018-03-01

Cresol is a prototype molecule in understanding intermolecular interactions in material and biological systems, because it offers different binding sites with various solvents and protonation states under different pH values. It is found that the UV/Vis absorption spectra of o -cresol in aromatic solvents (benzene, toluene) are characterized by a sharp peak, unlike the broad double-peaks in 11 non-aromatic solvents. Both molecular dynamics simulations and electronic structure calculations revealed the formation of intermolecular π-complexation between o -cresol and aromatic solvents. The thermal movements of solvent and solute molecules render the conformations of o -cresol changing between trans and cis isomers. The π-interaction makes the cis configuration a dominant isomer, hence leading to the single keen-edged UV/Vis absorption peak at approximately 283 nm. The free conformation changes between trans and cis in aqueous solution rationalize the broader absorption peaks in the range of 260-280 nm. The pH dependence of the UV/Vis absorption spectra in aqueous solutions is also rationalized by different protonation states of o -cresol. The explicit solvent model with long-ranged interactions is vital to describe the effects of π-complexation and electrostatic interaction on the UV/Vis absorption spectra of o -cresol in toluene and alkaline aqueous (pH > 10.3) solutions, respectively.

Radical protection by differently composed creams in the UV/VIS and IR spectral ranges.

Science.gov (United States)

Meinke, Martina C; Syring, Felicia; Schanzer, Sabine; Haag, Stefan F; Graf, Rüdiger; Loch, Manuela; Gersonde, Ingo; Groth, Norbert; Pflücker, Frank; Lademann, Jürgen

2013-01-01

Modern sunscreens are well suited to provide sufficient protection in the UV range because the filter substances absorb or scatter UV radiation. Although up to 50% of radicals are formed in the visible and infrared spectral range during solar radiation protection strategies are not provided in this range. Previous investigations of commercially available products have shown that in addition to physical filters, antioxidants (AO) are necessary to provide protective effects in the infrared range by neutralizing already formed radicals. In this study, the efficacy of filter substances and AO to reduce radical formation in both spectral ranges was investigated after UV/VIS or IR irradiation. Optical properties and radical protection were determined for the investigated creams. It was found that organic UV filters lower radical formation in the UV/VIS range to 35% compared to untreated skin, independent of the presence of AO. Further reduction to 14% was reached by addition of 2% physical filters, whereas physical filters alone were ineffective in the UV/VIS range due to the low concentration. In contrast, this filter type reduced radical formation in the IR range significantly to 65%; similar effects were aroused after application of AO. Sunscreens which contain organic UV filters, physical filters and AO ensure protection in the complete solar spectrum. © 2013 The American Society of Photobiology.

Robotic UV-Vis apparatus for long-term characterization of drug release from nanochannels

International Nuclear Information System (INIS)

Geninatti, T; Grattoni, A; Small, E

2014-01-01

Reliable monitoring of the kinetics of molecular release from drug delivery devices is crucial for their therapeutic success. Commercially available UV-Vis spectrophotometers provide reliable quantification of analyte concentrations directly correlated to the absorbance of fluids. However, they are not suitable for long-term measurements requiring high frequency of sampling from a large number of replicates and continuous fluid mixing, all of which are necessary for evaluation of drug delivery devices. To address this need, we developed a novel robotic apparatus serially connected to a commercial UV-Vis spectrophotometer. The robotic apparatus enables us to automatically and reliably acquire long-term data for up to 48 samples with high frequency of measurements and independent magnetic stirring. We equipped the robotic apparatus with independent connectors that allowed us to apply an electric potential to each sample for electrokinetic studies. The apparatus repeatability and accuracy was demonstrated in comparison to a commercial UV-Vis spectrophotometer. The system was successfully employed to characterize the diffusion kinetics of acetone and doxorubicin through nanochannel membranes (nDS) designed for long-term drug delivery. Dendritic fullerene 1 was used to show that the robotic apparatus routes the electric potential to nanochannel membranes enabling us to investigate the actively controlled release of molecules. Our results demonstrate that the robotic apparatus could widely broaden the range of applications of UV-Vis spectrophotometry, especially in the case of large sample processing and for long-term diffusive and electrokinetic studies in drug delivery. (technical design note)

In situ UV-vis spectroelectrochemistry of poly(o-phenylenediamine-co-m-toluidine)

International Nuclear Information System (INIS)

Bilal, Salma; Holze, Rudolf

2007-01-01

Results of in situ UV-vis spectroelectrochemical studies of the electropolymerization of o-phenylenediamine (OPD), m-toluidine (MT) and the copolymerization of OPD with MT are reported. Electropolymerization was performed in aqueous acidic medium at a constant potential of E SCE = 1.0 V at an indium doped tin oxide (ITO) coated glass electrode. The course of homopolymerization was followed for MT and OPD solutions with various monomer concentrations. The spectral characteristics of the mixed solutions were studied at a constant concentration of MT and various concentrations of OPD in the comonomer feed. An absorption band at λ = 497 nm was assigned to the head-to-tail mixed dimer/oligomer resulting from the cross reaction between OPD and MT cation radicals. UV-vis spectra recorded during copolymerization show dependence of the growth of the band at λ = 497 nm on OPD concentration in the feed. At lower OPD feed concentration it appears as the major band in the corresponding spectra. The UV-vis spectra recorded for the copolymer films suggest the incorporation of both monomer units in the copolymer. The FT-IR spectra of the copolymers show the presence of phenazine type structures in the copolymer backbone

Reaction pathways of proton transfer in hydrogen-bonded phenol-carboxylate complexes explored by combined UV-vis and NMR spectroscopy.

Science.gov (United States)

Koeppe, Benjamin; Tolstoy, Peter M; Limbach, Hans-Heinrich

2011-05-25

Combined low-temperature NMR/UV-vis spectroscopy (UVNMR), where optical and NMR spectra are measured in the NMR spectrometer under the same conditions, has been set up and applied to the study of H-bonded anions A··H··X(-) (AH = 1-(13)C-2-chloro-4-nitrophenol, X(-) = 15 carboxylic acid anions, 5 phenolates, Cl(-), Br(-), I(-), and BF(4)(-)). In this series, H is shifted from A to X, modeling the proton-transfer pathway. The (1)H and (13)C chemical shifts and the H/D isotope effects on the latter provide information about averaged H-bond geometries. At the same time, red shifts of the π-π* UV-vis absorption bands are observed which correlate with the averaged H-bond geometries. However, on the UV-vis time scale, different tautomeric states and solvent configurations are in slow exchange. The combined data sets indicate that the proton transfer starts with a H-bond compression and a displacement of the proton toward the H-bond center, involving single-well configurations A-H···X(-). In the strong H-bond regime, coexisting tautomers A··H···X(-) and A(-)···H··X are observed by UV. Their geometries and statistical weights change continuously when the basicity of X(-) is increased. Finally, again a series of single-well structures of the type A(-)···H-X is observed. Interestingly, the UV-vis absorption bands are broadened inhomogeneously because of a distribution of H-bond geometries arising from different solvent configurations.

P 8: Table-top instrumentation for time-resolved luminescence spectroscopy of solids excited by soft X-ray from a laser induced plasma source and/or UV-VIS laser

International Nuclear Information System (INIS)

Bruza, P.; Fidler, V.; Nikl, M.

2010-01-01

The design and use of a novel, table-top UV-VIS luminescence spectrometer with two excitation sources is described: a soft X-ray/XUV pulse excitation from the laser-produced plasma in gas puff target of about 4 ns duration, and a conventional N 2 pulse laser excitation at 337 nm (or any other UV-VIS pulse laser excitation). The XUV plasma source generates photons of either quasi-monochromatic (N target, E = 430 eV) or wide (Ar target, E = 200 ∼ 600 eV) spectral range. A combination of both X-ray/XUV and UV-VIS excitation in one experimental apparatus allows to perform comparative luminescence spectra and kinetics measurements under the same experimental conditions. In order to demonstrate the spectrometer, the UV-VIS luminescence spectra and decay kinetics of cerium doped Lu 3 Al 5 O 12 single crystal (LuAG:Ce) scintillator excited by XUV and UV radiation were acquired. Luminescence of doped Ce 3+ ions was studied under XUV 430 eV excitation from the laser-produced nitrogen plasma, and compared with the luminescence under 337 nm (3,68 eV) UV excitation from nitrogen laser. In the former case the excitation energy is deposited in the LuAG host, while in the latter the 4f-5d transition of Ce 3+ is directly excited. Furthermore, LuAG:Ce single crystals and single crystalline films luminescence decay profiles are compared and discussed. (authors)

UV/Vis and NIR Light-Responsive Spiropyran Self-Assembled Monolayers

NARCIS (Netherlands)

Ivashenko, Oleksii; Herpt, Jochem T. van; Feringa, Ben L.; Rudolf, Petra; Browne, Wesley R.

2013-01-01

Self-assembled monolayers of a 6-nitro BIPS spiropyran (SP) modified with a disulfide-terminated aliphatic chain were prepared on polycrystalline gold surfaces and characterized by UV/vis absorption, surface-enhanced Raman scattering (SEAS), and X-ray photoelectron spectroscopies (XPS). The SAMs

Instrumental Analysis in the High School Classroom: UV-Vis Spectroscopy

Science.gov (United States)

Erhardt, Walt

2007-01-01

Note is presented on the standard lab from a second year chemistry course. The lab "Determining which of the Seven FD&C Food-Approved Dyes are Used in Making Green Skittles", familiarizes students with the operation of the CHEM2000 UV-Vis spectrophorometer.

High efficiency single frequency 355 nm all-solid-state UV laser

International Nuclear Information System (INIS)

Xie, Xiaobing; Wei, Daikang; Ma, Xiuhua; Li, Shiguang; Liu, Jiqiao; Zhu, Xiaolei; Chen, Weibiao

2016-01-01

A novel conductively cooled high energy single-frequency 355 nm all-solid-state UV laser is presented based on sum-frequency mixing technique. In this system, a pulsed seeder laser at 1064 nm wavelength, modulated by an AOM, is directly amplified by the cascaded multi-stage hybrid laser amplifiers, and two LBO crystals are used for the SHG and SFG, finally a maximum UV pulse energy of 226 mJ at 355 nm wavelength is achieved with frequency-tripled conversion efficiency as high as 55%, the pulse width is around 12.2 ns at the repetition frequency of 30 Hz. The beam quality factor M 2 of the output UV laser is measured to be 2.54 and 2.98 respectively in two orthogonal directions. (paper)

UV-vis Imaging of Piroxicam Supersaturation, Precipitation, and Dissolution in a Flow-Through Setup.

Science.gov (United States)

Sun, Yu; Chapman, Alex; Larsen, Susan W; Jensen, Henrik; Petersen, Nickolaj J; Goodall, David M; Østergaard, Jesper

2018-06-05

Evaluation of drug precipitation is important in order to address challenges regarding low and variable bioavailability of poorly water-soluble drugs, to assess potential risk of patient safety with infusion therapy, and to explore injectable in situ suspension-forming drug delivery systems. Generally, drug precipitation is assessed in vitro through solution concentration analysis methods. Dual-wavelength UV-vis imaging is a novel imaging technique that may provide an opportunity for simultaneously monitoring changes in both solution and solid phases during precipitation. In the present study, a multimodal approach integrating UV-vis imaging, light microscopy, and Raman spectroscopy was developed for characterization of piroxicam supersaturation, precipitation, and dissolution in a flow-through setup. A solution of piroxicam dissolved in 1-methyl-2-pyrrolidinone was injected into a flowing aqueous environment (pH 7.4), causing piroxicam to precipitate. Imaging at 405 and 280 nm monitored piroxicam concentration distributions during precipitation and revealed different supersaturation levels dependent on the initial concentration of the piroxicam solution. The combination with imaging at 525 nm, light microscopy, and Raman spectroscopy measurements demonstrated concentration-dependent precipitation and the formation, growth, and dissolution of individual particles. Results emphasize the importance of the specific hydrodynamic conditions on the piroxicam precipitation. The approach used may facilitate comprehensive understanding of drug precipitation and dissolution processes and may be developed further into a basic tool for formulation screening and development.

Thermoluminescent properties of polycrystalline carbon doped LaAlO3/La(OH)3 crystals synthesized by solid state reaction for application in UV dosimetry

International Nuclear Information System (INIS)

Alves, N.; Oliveira de F, L.; Barbosa F, W.

2017-10-01

It is well known that UV radiation can induce certain deleterious effects, such as erythema, painful inflammation of the membrane of the eye and skin cancer. Therefore, it has been pushing the research for producing new and high performance UV sensitive Tl materials. There is an increasing interest in the development of new Tl materials for ultraviolet (UV) dosimetry purposes, owing to simplicity of the sample readout compared to other techniques. In this paper, thermoluminescence and dosimetric characteristics of pure and carbon doped lanthanum aluminate and hydroxide lanthanum crystals, irradiated with different UV doses, were studied and discussed. All samples studied were produced by solid state reaction method with different mixing methodologies. Characterization of sintered powders by X-ray diffraction, UV-Vis spectrophotometry and Ftir spectroscopy were performed. XRD data confirmed the LaAlO 3 and La(OH) 3 crystalline phases. The thermoluminescent study revealed that all compositions presented high UV sensibility. The sample which was grown by first sintering La 2 O 3 together carbon atoms and then sintering again in order to obtain La 2 O 3 :C together Al 2 O 3 , presented the best linear dose response over UV doses ranging from 0.042 to 0.63 mJ/cm 2 , with correlation coefficients equal to 0.99931. The synthesis methodology used was very efficient to obtain crystals with high Tl output intensities for low exposure rate UV R fields. (Author)

Mono- and bimetallic nanoparticles decorated KTaO3 photocatalysts with improved Vis and UV-Vis light activity

Science.gov (United States)

Krukowska, Anna; Trykowski, Grzegorz; Winiarski, Michal Jerzy; Klimczuk, Tomasz; Lisowski, Wojciech; Mikolajczyk, Alicja; Pinto, Henry P.; Zaleska-Medynska, Adriana

2018-05-01

Novel mono- and bimetallic nanoparticles (MNPs and BNPs) decorated surface of perovskite-type KTaO3 photocatalysts were successfully synthesized by hydrothermal reaction of KTaO3 followed by photodeposition of MNPs/BNPs. The effect of noble metal type (MNPs = Au, Ag, Pt, Pd, Rh, Ru or BNPs = Au/Pt, Ag/Pd, Rh/Ru), amount of metal precursor (0.5, 1.0, 1.5 or 2.0 wt%) as well as photoreduction method (simultaneous (both) or subsequent (seq) deposition of two metals) on the physicochemical and photocatalytic properties of MNPs- and BNPs-KTaO3 have been investigated. All as-prepared photocatalysts were subsequently characterized by UV-Vis diffuse reflectance spectroscopy (DRS), Brunauer-Emmett-Teller (BET) specific surface area and pore size distribution measurement, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), powder X-ray diffraction (PXRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) emission spectroscopy. The crystal structure was performed using visualization for electronic and structural analysis (VESTA). The photocatalytic activity under Vis light irradiation was estimated in phenol degradation in aqueous phase and toluene removal in gas phase, while under UV-Vis light irradiation was measured amount of H2 generation from formic acid solution. The absorption properties of O2 and H2O molecules on KTaO3(1 0 0) surface supported by Au or Au/Pt NPs was also investigated using density-functional theory (DFT). The experimental results show that, both MNPs-KTaO3 and BNPs-KTaO3 exhibit greatly enhanced pollutant decomposition efficiency under Vis light irradiation and highly improved H2 production under UV-Vis light irradiation compared with pristine KTaO3. MNPs deposition on KTaO3 surface effects by disperse metal particle size ranging from 11 nm (Ru NPs) to 112 nm (Au NPs). Simultaneous addition of Au/Pt precursors results in formation of agglomerated

Photocatalytic performance of Sn-doped TiO2 nanostructured mono and double layer thin films for Malachite Green dye degradation under UV and vis-lights

International Nuclear Information System (INIS)

Sayilkan, F.; Asiltuerk, M.; Tatar, P.; Kiraz, N.; Arpac, E.; Sayilkan, H.

2007-01-01

Nanostructure Sn 4+ -doped TiO 2 based mono and double layer thin films, contain 50% solid ratio of TiO 2 in coating have been prepared on glass surfaces by spin-coating technique. Their photocatalytic performances were tested for degradation of Malachite Green dye in solution under UV and vis irradiation. Sn 4+ -doped nano-TiO 2 particle a doping ratio of about 5[Sn 4+ /Ti(OBu n ) 4 ; mol/mol%] has been synthesized by hydrotermal process at 225 deg. C. The structure, surface and optical properties of the thin films and/or the particles have been investigated by XRD, BET and UV/vis/NIR techniques. The results showed that the double layer coated glass surfaces have a very high photocatalytic performance than the other one under UV and vis lights. The results also proved that the hydrothermally synthesized nano-TiO 2 particles are fully anatase crystalline form and are easily dispersed in water. The results also reveal that the coated surfaces have hydrophilic property

Calibration curves for quantifying praseodymium by UV-VIS; Curvas de calibracion para cuantificar praseodimio por UV-VIS

Energy Technology Data Exchange (ETDEWEB)

Gonzalez M, R.; Lopez G, H.; Rojas H, A. [ININ, 52750 La Marquesa, Estado de Mexico (Mexico)]. e-mail: robertssd1199@yahoo.com.mx

2007-07-01

The UV-Vis spectroscopic technique was used to determine the absorption bands depending on the concentration from the praseodymium solutions at pH3. Those more appropriate were in the wavelength of 215 nm, for concentrations of 0.0001-0.026 M, of 481nm, 468 nm and 443 nm, for concentrations of 0.026-0.325 M, and of 589 nm, for concentrations of 0.026-0.65 M of the praseodymium. To these wavelengths the calibration curves were determined, which presented correlation coefficients between 0.9976 and 0.9999 except of the absorption of 589 nm that gave R{sup 2} = 0.9014. (Author)

Following the Formation of Active Co(III) Sites in Cobalt Substituted Aluminophosphates Catalysts by In-Situ Combined UV-VIS/XAFS/XRD Technique

International Nuclear Information System (INIS)

Sankar, Gopinathan; Fiddy, Steven; Harvey, Ian; Hayama, Shusaku; Bushnell-Wye, Graham; Beale, Andrew M.

2007-01-01

Cobalt substituted aluminophosphates, CoAlPO-34 (Chabazite structure) and DAF-8 (Phillipsite structure) were investigated by in situ combined XRD/EXAFS/UV-VIS technique. In-situ combined XRD, Co K-edge EXAFS and UV-Vis measurements carried out during the calcination process reveal that CoAlPO-34 containing 10 wt percent cobalt is stable and the cobalt ions are converted from Co(II) in the as synthesised form to Co(III); DAF-8 containing about 25 percent cobalt is not stable and does not show change in oxidation state

Využití UV/VIS spektrofotometrie pro stanovení diklofenaku

Czech Academy of Sciences Publication Activity Database

Čapka, Lukáš; Zlámalová Gargošová, H.; Vávrová, M.; Urbánková, L.

2013-01-01

Roč. 107, č. 7 (2013), s. 550-554 ISSN 0009-2770 Institutional support: RVO:68081715 Keywords : diclofenac * UV-VIS spectrophotometry * environment * fate * pharmaceutical residues Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 0.196, year: 2013

Instrumentation: Photodiode Array Detectors in UV-VIS Spectroscopy. Part II.

Science.gov (United States)

Jones, Dianna G.

1985-01-01

A previous part (Analytical Chemistry; v57 n9 p1057A) discussed the theoretical aspects of diode ultraviolet-visual (UV-VIS) spectroscopy. This part describes the applications of diode arrays in analytical chemistry, also considering spectroelectrochemistry, high performance liquid chromatography (HPLC), HPLC data processing, stopped flow, and…

Screening of Satureja subspicata Vis. Honey by HPLC-DAD, GC-FID/MS and UV/VIS: Prephenate Derivatives as Biomarkers.

Science.gov (United States)

Jerković, Igor; Kranjac, Marina; Marijanović, Zvonimir; Zekić, Marina; Radonić, Ani; Tuberoso, Carlo Ignazio Giovanni

2016-03-21

The samples of Satureja subspicata Vis. honey were confirmed to be unifloral by melissopalynological analysis with the characteristic pollen share from 36% to 71%. Bioprospecting of the samples was performed by HPLC-DAD, GC-FID/MS, and UV/VIS. Prephenate derivatives were shown to be dominant by the HPLC-DAD analysis, particularly phenylalanine (167.8 mg/kg) and methyl syringate (MSYR, 114.1 mg/kg), followed by tyrosine and benzoic acid. Higher amounts of MSYR (3-4 times) can be pointed out for distinguishing S. subspicata Vis. honey from other Satureja spp. honey types. GC-FID/MS analysis of ultrasonic solvent extracts of the samples revealed MSYR (46.68%, solvent pentane/Et2O 1:2 (v/v); 52.98%, solvent CH2Cl2) and minor abundance of other volatile prephenate derivatives, as well as higher aliphatic compounds characteristic of the comb environment. Two combined extracts (according to the solvents) of all samples were evaluated for their antioxidant properties by FRAP and DPPH assay; the combined extracts demonstrated higher activity (at lower concentrations) in comparison with the average honey sample. UV/VIS analysis of the samples was applied for determination of CIE Lab colour coordinates, total phenolics (425.38 mg GAE/kg), and antioxidant properties (4.26 mmol Fe(2+)/kg (FRAP assay) and 0.8 mmol TEAC/kg (DDPH assay)).

Inline UV/Vis spectroscopy as PAT tool for hot-melt extrusion.

Science.gov (United States)

Wesholowski, Jens; Prill, Sebastian; Berghaus, Andreas; Thommes, Markus

2018-01-11

Hot-melt extrusion on co-rotating twin screw extruders is a focused technology for the production of pharmaceuticals in the context of Quality by Design. Since it is a continuous process, the potential for minimizing product quality fluctuation is enhanced. A typical application of hot-melt extrusion is the production of solid dispersions, where an active pharmaceutical ingredient (API) is distributed within a polymer matrix carrier. For this dosage form, the product quality is related amongst others to the drug content. This can be monitored on- or inline as critical quality attribute by a process analytical technology (PAT) in order to meet the specific requirements of Quality by Design. In this study, an inline UV/Vis spectrometer from ColVisTec was implemented in an early development twin screw extruder and the performance tested in accordance to the ICH Q2 guideline. Therefore, two API (carbamazepine and theophylline) and one polymer matrix (copovidone) were considered with the main focus on the quantification of the drug load. The obtained results revealed the suitability of the implemented PAT tool to quantify the drug load in a typical range for pharmaceutical applications. The effort for data evaluation was minimal due to univariate data analysis, and in combination with a measurement frequency of 1 Hz, the system is sufficient for real-time data acquisition.

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

Science.gov (United States)

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.

Thermoluminescent properties of polycrystalline carbon doped LaAlO{sub 3}/La(OH){sub 3} crystals synthesized by solid state reaction for application in UV dosimetry

Energy Technology Data Exchange (ETDEWEB)

Alves, N.; Oliveira de F, L. [Federal University of the State of Minas Gerais, Department of Nuclear Engineering, Av. Pres. Antonio Carlos 6627, 31270-901 Belo Horizonte, Minas Gerais (Brazil); Barbosa F, W., E-mail: neire.radiologia@yahoo.com.br [Nuclear Technology Development Center, 941, 30161-970 Belo Horizonte, Minas Gerais (Brazil)

2017-10-15

It is well known that UV radiation can induce certain deleterious effects, such as erythema, painful inflammation of the membrane of the eye and skin cancer. Therefore, it has been pushing the research for producing new and high performance UV sensitive Tl materials. There is an increasing interest in the development of new Tl materials for ultraviolet (UV) dosimetry purposes, owing to simplicity of the sample readout compared to other techniques. In this paper, thermoluminescence and dosimetric characteristics of pure and carbon doped lanthanum aluminate and hydroxide lanthanum crystals, irradiated with different UV doses, were studied and discussed. All samples studied were produced by solid state reaction method with different mixing methodologies. Characterization of sintered powders by X-ray diffraction, UV-Vis spectrophotometry and Ftir spectroscopy were performed. XRD data confirmed the LaAlO{sub 3} and La(OH){sub 3} crystalline phases. The thermoluminescent study revealed that all compositions presented high UV sensibility. The sample which was grown by first sintering La{sub 2}O{sub 3} together carbon atoms and then sintering again in order to obtain La{sub 2}O{sub 3}:C together Al{sub 2}O{sub 3}, presented the best linear dose response over UV doses ranging from 0.042 to 0.63 mJ/cm{sup 2}, with correlation coefficients equal to 0.99931. The synthesis methodology used was very efficient to obtain crystals with high Tl output intensities for low exposure rate UV R fields. (Author)

Development and validation of a FIA/UV-vis method for pK(a) determination of oxime based acetylcholinesterase reactivators.

Science.gov (United States)

Musil, Karel; Florianova, Veronika; Bucek, Pavel; Dohnal, Vlastimil; Kuca, Kamil; Musilek, Kamil

2016-01-05

Acetylcholinesterase reactivators (oximes) are compounds used for antidotal treatment in case of organophosphorus poisoning. The dissociation constants (pK(a1)) of ten standard or promising acetylcholinesterase reactivators were determined by ultraviolet absorption spectrometry. Two methods of spectra measurement (UV-vis spectrometry, FIA/UV-vis) were applied and compared. The soft and hard models for calculation of pK(a1) values were performed. The pK(a1) values were recommended in the range 7.00-8.35, where at least 10% of oximate anion is available for organophosphate reactivation. All tested oximes were found to have pK(a1) in this range. The FIA/UV-vis method provided rapid sample throughput, low sample consumption, high sensitivity and precision compared to standard UV-vis method. The hard calculation model was proposed as more accurate for pK(a1) calculation. Copyright © 2015 Elsevier B.V. All rights reserved.

In situ ESR/UV-vis-NIR and ATR-FTIR spectroelectrochemical studies on the p-doping of copolymers of 3-methylthiophene and 3-hexylthiophene.

Science.gov (United States)

Cházaro-Ruiz, Luis F; Kellenberger, Andrea; Dunsch, Lothar

2009-02-26

A combined spectroelectrochemical study by ESR/UV-vis-NIR as well as FTIR spectroscopy on the influence of the copolymer composition on the stabilization of charges upon electrochemical p-doping is presented. As compared to the parent homopolymers 3-hexylthiophene (3-HeTh) and 3-methylthiophene (3-MeTh) which seems to be irregular, FTIR studies of the copolymer of both monomers (copMeHeTh) point to a regioregular structure. The in situ ESR and UV-vis-NIR spectroelectrochemistry at higher doping levels of the polymeric materials proves bipolarons and polaron pairs as stable charged states in poly(3-hexylthiophene) as well as the copolymer copMeHeTh. During the p-doping of poly(3-methylthiophene) bipolarons are the dominating species at higher doping levels. It is demonstrated that only the simultaneous use of both the ESR and the UV-vis-NIR spectroscopy enables the differentiation of polarons (paramagnetic) and polaron pairs (diamagnetic) in a conducting polymer.

Charged states of alpha,omega-dicyano beta, beta' - dibutylquaterthiophene as studied by in situ ESR UV-Vis NIR spectroelectrochemistry

Czech Academy of Sciences Publication Activity Database

Haubner, K.; Tarábek, Ján; Ziegs, F.; Lukeš, V.; Jaehne, E.; Dunsch, L.

2010-01-01

Roč. 114, č. 43 (2010), s. 11545-11551 ISSN 1089-5639 Grant - others:GA ČR(CZ) GC203/07/J067 Program:GC Institutional research plan: CEZ:AV0Z40550506 Keywords : cyclic voltammetry * ESR/UV-Vis NIR spectrometry * spectroelectrochemistry * thiophene oligomer * dimerisation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.732, year: 2010

Identification of intermediates in zeolite-catalyzed reactions by in situ UV/Vis microspectroscopy and a complementary set of molecular simulations.

Science.gov (United States)

Hemelsoet, Karen; Qian, Qingyun; De Meyer, Thierry; De Wispelaere, Kristof; De Sterck, Bart; Weckhuysen, Bert M; Waroquier, Michel; Van Speybroeck, Veronique

2013-12-02

The optical absorption properties of (poly)aromatic hydrocarbons occluded in a nanoporous environment were investigated by theoretical and experimental methods. The carbonaceous species are an essential part of a working catalyst for the methanol-to-olefins (MTO) process. In situ UV/Vis microscopy measurements on methanol conversion over the acidic solid catalysts H-SAPO-34 and H-SSZ-13 revealed the growth of various broad absorption bands around 400, 480, and 580 nm. The cationic nature of the involved species was determined by interaction of ammonia with the methanol-treated samples. To determine which organic species contribute to the various bands, a systematic series of aromatics was analyzed by means of time-dependent density functional theory (TDDFT) calculations. Static gas-phase simulations revealed the influence of structurally different hydrocarbons on the absorption spectra, whereas the influence of the zeolitic framework was examined by using supramolecular models within a quantum mechanics/molecular mechanics framework. To fully understand the origin of the main absorption peaks, a molecular dynamics (MD) study on the organic species trapped in the inorganic host was essential. During such simulation the flexibility is fully taken into account and the effect on the UV/Vis spectra is determined by performing TDDFT calculations on various snapshots of the MD run. This procedure allows an energy absorption scale to be provided and the various absorption bands determined from in situ UV/Vis spectra to be assigned to structurally different species. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Forecasting of UV-Vis absorbance time series using artificial neural networks combined with principal component analysis.

Science.gov (United States)

Plazas-Nossa, Leonardo; Hofer, Thomas; Gruber, Günter; Torres, Andres

2017-02-01

This work proposes a methodology for the forecasting of online water quality data provided by UV-Vis spectrometry. Therefore, a combination of principal component analysis (PCA) to reduce the dimensionality of a data set and artificial neural networks (ANNs) for forecasting purposes was used. The results obtained were compared with those obtained by using discrete Fourier transform (DFT). The proposed methodology was applied to four absorbance time series data sets composed by a total number of 5705 UV-Vis spectra. Absolute percentage errors obtained by applying the proposed PCA/ANN methodology vary between 10% and 13% for all four study sites. In general terms, the results obtained were hardly generalizable, as they appeared to be highly dependent on specific dynamics of the water system; however, some trends can be outlined. PCA/ANN methodology gives better results than PCA/DFT forecasting procedure by using a specific spectra range for the following conditions: (i) for Salitre wastewater treatment plant (WWTP) (first hour) and Graz West R05 (first 18 min), from the last part of UV range to all visible range; (ii) for Gibraltar pumping station (first 6 min) for all UV-Vis absorbance spectra; and (iii) for San Fernando WWTP (first 24 min) for all of UV range to middle part of visible range.

Diagnostic spectroscopic and computer-aided evaluation of malignancy from UV/VIS spectra of clear pleural effusions

Science.gov (United States)

Jevtić, Dubravka R.; Avramov Ivić, Milka L.; Reljin, Irini S.; Reljin, Branimir D.; Plavec, Goran I.; Petrović, Slobodan D.; Mijin, Dušan Ž.

2014-06-01

The automated, computer-aided method for differentiation and classification of malignant (M) from benign (B) cases, by analyzing the UV/VIS spectra of pleural effusions is described. It was shown that by two independent objective features, the maximum of Katz fractal dimension (KFDmax) and the area under normalized UV/VIS absorbance curve (Area), highly reliable M-B classification is possible. In the Area-KFDmax space M and B samples are linearly separable permitting thus the use of linear support vector machine as a classification tool. By analyzing 104 samples of UV/VIS spectra of pleural effusions (88 M and 16 B) collected from patients at the Clinic for Lung Diseases and Tuberculosis, Military Medical Academy in Belgrade, the accuracy of 95.45% for M cases and 100% for B cases are obtained by using the proposed method. It was shown that by applying some modifications, which are suggested in the paper, the accuracy of 100% for M cases can be reached.

Determination of the electronic structure and UV-Vis absorption properties of (Na2-xCux)Ta4O11 from first-principle calculations

KAUST Repository

Harb, Moussab; Masih, Dilshad; Ould-Chikh, Samy; Sautet, Philippe; Basset, Jean-Marie; Takanabe, Kazuhiro

2013-01-01

the optical transitions in these materials using the screened coulomb hybrid (HSE06) exchange-correlation formalism. The calculated density of states showed excellent agreement with UV-vis diffuse reflectance spectra predicting a significant red

UV-Vis as quantification tool for solubilized lignin following a single-shot steam process.

Science.gov (United States)

Lee, Roland A; Bédard, Charles; Berberi, Véronique; Beauchet, Romain; Lavoie, Jean-Michel

2013-09-01

In this short communication, UV/Vis was used as an analytical tool for the quantification of lignin concentrations in aqueous mediums. A significant correlation was determined between absorbance and concentration of lignin in solution. For this study, lignin was produced from different types of biomasses (willow, aspen, softwood, canary grass and hemp) using steam processes. Quantification was performed at 212, 225, 237, 270, 280 and 287 nm. UV-Vis quantification of lignin was found suitable for different types of biomass making this a timesaving analytical system that could lead to uses as Process Analytical Tool (PAT) in biorefineries utilizing steam processes or comparable approaches. Copyright © 2013 Elsevier Ltd. All rights reserved.

Detection Limits of DLS and UV-Vis Spectroscopy in Characterization of Polydisperse Nanoparticles Colloids

Directory of Open Access Journals (Sweden)

Emilia Tomaszewska

2013-01-01

Full Text Available Dynamic light scattering is a method that depends on the interaction of light with particles. This method can be used for measurements of narrow particle size distributions especially in the range of 2–500 nm. Sample polydispersity can distort the results, and we could not see the real populations of particles because big particles presented in the sample can screen smaller ones. Although the theory and mathematical basics of DLS technique are already well known, little has been done to determine its limits experimentally. The size and size distribution of artificially prepared polydisperse silver nanoparticles (NPs colloids were studied using dynamic light scattering (DLS and ultraviolet-visible (UV-Vis spectroscopy. Polydisperse colloids were prepared based on the mixture of chemically synthesized monodisperse colloids well characterized by atomic force microscopy (AFM, transmission electron microscopy (TEM, DLS, and UV-Vis spectroscopy. Analysis of the DLS results obtained for polydisperse colloids reveals that several percent of the volume content of bigger NPs could screen completely the presence of smaller ones. The presented results could be extremely important from nanoparticles metrology point of view and should help to understand experimental data especially for the one who works with DLS and/or UV-Vis only.

Application of Time-Dependent Density Functional and Natural Bond Orbital Theories to the UV-vis Absorption Spectra of Some Phenolic Compounds.

Science.gov (United States)

Marković, Svetlana; Tošović, Jelena

2015-09-03

The UV-vis properties of 22 natural phenolic compounds, comprising anthraquinones, neoflavonoids, and flavonoids were systematically examined. The time-dependent density functional theory (TDDFT) approach in combination with the B3LYP, B3LYP-D2, B3P86, and M06-2X functionals was used to simulate the UV-vis spectra of the investigated compounds. It was shown that all methods exhibit very good (B3LYP slightly better) performance in reproducing the examined UV-vis spectra. However, the shapes of the Kohn-Sham molecular orbitals (MOs) involved in electronic transitions were misleading in constructing the MO correlation diagrams. To provide better understanding of redistribution of electron density upon excitation, the natural bond orbital (NBO) analysis was applied. Bearing in mind the spatial and energetic separations, as well as the character of the π bonding, lone pair, and π* antibonding natural localized molecular orbitals (NLMOs), the "NLMO clusters" were constructed. NLMO cluster should be understood as a part of a molecule characterized with distinguished electron density. It was shown that all absorption bands including all electronic transitions need to be inspected to fully understand the UV-vis spectrum of a certain compound, and, thus, to learn more about its UV-vis light absorption. Our investigation showed that the TDDFT and NBO theories are complementary, as the results from the two approaches can be combined to interpret the UV-vis spectra. Agreement between the predictions of the TDDFT approach and those based on the NLMO clusters is excellent in the case of major electronic transitions and long wavelengths. It should be emphasized that the approach for investigation of UV-vis light absorption based on the NLMO clusters is applied for the first time.

Applications of UV/Vis Spectroscopy in Characterization and Catalytic Activity of Noble Metal Nanoparticles Fabricated in Responsive Polymer Microgels: A Review.

Science.gov (United States)

Begum, Robina; Farooqi, Zahoor H; Naseem, Khalida; Ali, Faisal; Batool, Madeeha; Xiao, Jianliang; Irfan, Ahmad

2018-11-02

Noble metal nanoparticles loaded smart polymer microgels have gained much attention due to fascinating combination of their properties in a single system. These hybrid systems have been extensively used in biomedicines, photonics, and catalysis. Hybrid microgels are characterized by using various techniques but UV/Vis spectroscopy is an easily available technique for characterization of noble metal nanoparticles loaded microgels. This technique is widely used for determination of size and shape of metal nanoparticles. The tuning of optical properties of noble metal nanoparticles under various stimuli can be studied using UV/Vis spectroscopic method. Time course UV/Vis spectroscopy can also be used to monitor the kinetics of swelling and deswelling of microgels and hybrid microgels. Growth of metal nanoparticles in polymeric network or growth of polymeric network around metal nanoparticle core can be studied by using UV/Vis spectroscopy. This technique can also be used for investigation of various applications of hybrid materials in catalysis, photonics, and sensing. This tutorial review describes the uses of UV/Vis spectroscopy in characterization and catalytic applications of responsive hybrid microgels with respect to recent research progress in this area.

Benchmark studies of UV-vis spectra simulation for cinnamates with UV filter profile.

Science.gov (United States)

Garcia, Ricardo D'A; Maltarollo, Vinícius G; Honório, Káthia M; Trossini, Gustavo H G

2015-06-01

Skin cancer is a serious public health problem worldwide, being incident over all five continents and affecting an increasing number of people. As sunscreens are considered an important preventive measure, studies to develop better and safer sunscreens are crucial. Cinnamates are UVB filters with good efficiency and cost-benefit, therefore, their study could lead to the development of new UV filters. A benchmark to define the most suitable density functional theory (DFT) functional to predict UV-vis spectra for ethylhexyl methoxycinnamate was performed. Time-dependent DFT (TD-DFT) calculations were then carried out [B3LYP/6-311 + G(d,p) and B3P86/6-311 + G(d,p) in methanol environment] for seven cinammete derivatives implemented in the Gaussian 03 package. All DFT/TD-DFT simulations were performed after a conformational search with the Monte-Carlo method and MMFF94 force field. B3LYP and B3P86 functionals were better at reproducing closely the experimental spectra of ethylhexyl methoxycinnamate. Calculations of seven cinnamates showed a λmax of around 310 nm, corroborating literature reports. It was observed that the energy for the main electronic transition was around 3.95 eV and could be explained by electron delocalization on the aromatic ring and ester group, which is important to UV absorption. The methodology employed proved to be suitable for determination of the UV spectra of cinnamates and could be used as a tool for the development of novel UV filters.

Calibration curves for quantifying praseodymium by UV-VIS

International Nuclear Information System (INIS)

Gonzalez M, R.; Lopez G, H.; Rojas H, A.

2007-01-01

The UV-Vis spectroscopic technique was used to determine the absorption bands depending on the concentration from the praseodymium solutions at pH3. Those more appropriate were in the wavelength of 215 nm, for concentrations of 0.0001-0.026 M, of 481nm, 468 nm and 443 nm, for concentrations of 0.026-0.325 M, and of 589 nm, for concentrations of 0.026-0.65 M of the praseodymium. To these wavelengths the calibration curves were determined, which presented correlation coefficients between 0.9976 and 0.9999 except of the absorption of 589 nm that gave R 2 = 0.9014. (Author)

Enhanced selective photocatalytic reduction of CO2 to CH4 over plasmonic Au modified g-C3N4 photocatalyst under UV-vis light irradiation

Science.gov (United States)

Li, Hailong; Gao, Yan; Xiong, Zhuo; Liao, Chen; Shih, Kaimin

2018-05-01

A series of Au-g-C3N4 (Au-CN) catalysts were prepared through a NaBH4-reduction method using g-C3N4 (CN) from pyrolysis of urea as precursor. The catalysts' surface area, crystal structure, surface morphology, chemical state, functional group composition and optical properties were characterized by X-ray diffraction, transmission electron microscope, X-ray photoelectron spectroscopy, ultraviolet visible (UV-vis) diffuse reflectance spectra, fourier transform infrared, photoluminescence and transient photocurrent analysis. The carbon dioxide (CO2) photoreduction activities under ultraviolet visible (UV-vis) light irradiation were significantly enhanced when gold (Au) was loaded on the surface of CN. 2Au-CN catalyst with Au to CN mole ratio of 2% showed the best catalytic activity. After 2 h UV-vis light irradiation, the methane (CH4) yield over the 2Au-CN catalyst was 9.1 times higher than that over the pure CN. The CH4 selectivity also greatly improved for the 2Au-CN compared to the CN. The deposited Au nanoparticles facilitated the separation of electron-hole pairs on the CN surface. Moreover, the surface plasmon resonance effect of Au further promoted the generation of hot electrons and visible light absorption. Therefore, Au loading significantly improved CO2 photoreduction performance of CN under UV-vis light irradiation.

Using UV-VIS spectrophotometry for determining ecotoxicity of selected non-steroidal anti-inflammatory drugs

Czech Academy of Sciences Publication Activity Database

Čapka, Lukáš; Zlámalová Gargošová, H.; Vávrová, M.

2015-01-01

Roč. 24, 12C (2015), s. 4758-4762 ISSN 1018-4619 Institutional support: RVO:68081715 Keywords : ecotoxicity * NSAIDs * UV-VIS spectrophotometry Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 0.372, year: 2015

UV-Vis Ratiometric Resonance Synchronous Spectroscopy for Determination of Nanoparticle and Molecular Optical Cross Sections.

Science.gov (United States)

Nettles, Charles B; Zhou, Yadong; Zou, Shengli; Zhang, Dongmao

2016-03-01

Demonstrated herein is a UV-vis Ratiometric Resonance Synchronous Spectroscopic (R2S2, pronounced as "R-two-S-two" for simplicity) technique where the R2S2 spectrum is obtained by dividing the resonance synchronous spectrum of a NP-containing solution by the solvent resonance synchronous spectrum. Combined with conventional UV-vis measurements, this R2S2 method enables experimental quantification of the absolute optical cross sections for a wide range of molecular and nanoparticle (NP) materials that range optically from pure photon absorbers or scatterers to simultaneous photon absorbers and scatterers, simultaneous photon absorbers and emitters, and all the way to simultaneous photon absorbers, scatterers, and emitters in the UV-vis wavelength region. Example applications of this R2S2 method were demonstrated for quantifying the Rayleigh scattering cross sections of solvents including water and toluene, absorption and resonance light scattering cross sections for plasmonic gold nanoparticles, and absorption, scattering, and on-resonance fluorescence cross sections for semiconductor quantum dots (Qdots). On-resonance fluorescence quantum yields were quantified for the model molecular fluorophore Eosin Y and fluorescent Qdots CdSe and CdSe/ZnS. The insights and methodology presented in this work should be of broad significance in physical and biological science research that involves photon/matter interactions.

Vibrationally resolved UV/Vis spectroscopy with time-dependent density functional based tight binding

NARCIS (Netherlands)

Ruger, R.; Niehaus, T.; van Lenthe, E.; Heine, T.; Visscher, L.

2016-01-01

We report a time-dependent density functional based tight-binding (TD-DFTB) scheme for the calculation of UV/Vis spectra, explicitly taking into account the excitation of nuclear vibrations via the adiabatic Hessian Franck-Condon method with a harmonic approximation for the nu- clear wavefunction.

Effects of UV radiation on the UV-VIS absorption spectra of the EAGLE's medium components

International Nuclear Information System (INIS)

Bollmann, G.; Redmann, K.

1990-01-01

The impact of ultraviolet light on uv/vis absorption spectra of selected individual components of the cell breeding medium according to Eagle (MEM) was investigated. The strongest alterations of light absorption were detected in L-phenylalanin, L-tyrosin and L-tryptophane. Thus, the absorption behaviour of the Eagle (MEM) medium changed post radiationem may be attributed to spectrophotometric alterations of absorption in aromatic amino acids. The results are discussed with regard to the effect on the surface charge of erythrocytes. (author)

UV-Vis spectroscopy with chemometric data treatment. An option for on-line control in nuclear industry

International Nuclear Information System (INIS)

Kirsanov, Dmitry; Legin, Andrey

2017-01-01

Chemometrics can be very useful for the classical field of UV-Vis determination of metals in aqueous solutions. A conventional approach consisting of using selective bands in a univariate mode is often not applicable to the real-world samples from e.g. hydrometallurgical processes, because of overlapping signals, light scattering on foreign particles, gas bubble formation, etc. And this is where chemometrics can do a good job. This paper overviews certain contributions to the field of multivariate data processing of UV-Vis spectra for seemingly simple case of metal detection in aqueous solutions. Special attention is given to applications in nuclear technology field. (author)

Protonation effects on the UV/Vis absorption spectra of imatinib: a theoretical and experimental study.

Science.gov (United States)

Grante, Ilze; Actins, Andris; Orola, Liana

2014-08-14

An experimental and theoretical investigation of protonation effects on the UV/Vis absorption spectra of imatinib showed systematic changes of absorption depending on the pH, and a new absorption band appeared below pH 2. These changes in the UV/Vis absorption spectra were interpreted using quantum chemical calculations. The geometry of various imatinib cations in the gas phase and in ethanol solution was optimized with the DFT/B3LYP method. The resultant geometries were compared to the experimentally determined crystal structures of imatinib salts. The semi-empirical ZINDO-CI method was employed to calculate the absorption lines and electronic transitions. Our study suggests that the formation of the extra near-UV absorption band resulted from an increase of imatinib trication concentration in the solution, while the rapid increase of the first absorption maximum could be attributed to both the formation of imatinib trication and tetracation. Copyright © 2014 Elsevier B.V. All rights reserved.

Ultraviolet-Visible (UV-Vis) Microspectroscopic System Designed for the In Situ Characterization of the Dehydrogenation Reaction Over Platinum Supported Catalytic Microchannel Reactor.

Science.gov (United States)

Suarnaba, Emee Grace Tabares; Lee, Yi Fuan; Yamada, Hiroshi; Tagawa, Tomohiko

2016-11-01

An ultraviolet visible (UV-Vis) microspectroscopic system was designed for the in situ characterization of the activity of the silica supported platinum (Pt) catalyst toward the dehydrogenation of 1-methyl-1,4-cyclohexadiene carried out in a custom-designed catalytic microreactor cell. The in situ catalytic microreactor cell (ICMC) with inlet/outlet ports was prepared using quartz cover as the optical window to facilitate UV-Vis observation. A fabricated thermometric stage was adapted to the UV-Vis microspectrophotometer to control the reaction temperature inside the ICMC. The spectra were collected by focusing the UV-Vis beam on a 30 × 30 µm area at the center of ICMC. At 393 K, the sequential measurement of the spectra recorded during the reaction exhibited a broad absorption peak with maximum absorbance at 260 nm that is characteristic for gaseous toluene. This result indicates that the silica supported Pt catalyst is active towards the dehydrogenation of 1-methyl-1,4-cyclohexadiene at the given experimental conditions. The onset of coke formation was also detected based on the appearance of absorption bands at 300 nm. The UV-Vis microspectroscopic system developed can be used further in studying the mechanism of the dehydrogenation reaction. © The Author(s) 2016.

Photodetachment and UV-Vis spectral properties of Cl2rad -·nHO clusters: Extrapolation to bulk

Science.gov (United States)

Pathak, A. K.; Mukherjee, T.; Maity, D. K.

2008-03-01

Vertical detachment energy (VDE) and UV-Vis spectra of Cl2rad -·nHO clusters ( n = 1-11) are reported based on first principle electronic structure calculations. VDE of the hydrated clusters are calculated following second order Moller-Plesset perturbation (MP2) as well as coupled cluster theory with 6-311++G(d,p) set of basis function. The excess electron in these hydrated clusters is mainly localized over the solute Cl atoms. A linear relationship is obtained for VDE vs. ( n + 2.6) -1/3 and bulk VDE of Cl2rad - aqueous solution is calculated as 10.61 eV at CCSD(T) level of theory. UV-Vis spectra of these hydrated clusters are calculated applying CI with single electron (CIS) excitation procedure. Simulated UV-Vis spectra of Cl2rad -·10HO cluster is noted to be in excellent agreement with the reported spectra of Cl2rad - (aq) system, λmax for Cl2rad -·11HO system is calculated to be red shifted though.

Photocatalytic performance of Sn-doped TiO2 nanostructured thin films for photocatalytic degradation of malachite green dye under UV and VIS-lights

International Nuclear Information System (INIS)

Sayilkan, F.; Asiltuerk, M.; Tatar, P.; Kiraz, N.; Sener, S.; Arpac, E.; Sayilkan, H.

2008-01-01

Sn-doped and undoped nano-TiO 2 particles have been synthesized by hydrotermal process without acid catalyst at 225 deg. C in 1 h. Nanostructure-TiO 2 based thin films, contain at different solid ratio of TiO 2 in coating, have been prepared on glass surfaces by spin-coating technique. The structure, surface morphology and optical properties of the thin films and the particles have been investigated by element analysis and XRD, BET and UV/VIS/NIR techniques. The photocatalytic performance of the films was tested for degradation of malachite green dye in solution under UV and VIS-lights. The results showed that the hydrothermally synthesized nano-TiO 2 particles are fully anatase crystalline form and are easily dispersed in water, the coated surfaces have nearly super-hydrophilic properties and, the doping of transition metal ion efficiently improved the photocatalytic performance of the TiO 2 thin film. The results also proved that malachite green is decomposed catalytically due to the pseudo first-order reaction kinetics

New insight in the template decomposition process of large zeolite ZSM-5 crystals: an in situ UV-Vis/fluorescence micro-spectroscopy study

NARCIS (Netherlands)

Karwacki, L.|info:eu-repo/dai/nl/304824283; Weckhuysen, B.M.|info:eu-repo/dai/nl/285484397

2011-01-01

A combination of in situ UV-Vis and confocal fluorescence micro-spectroscopy was used to study the template decomposition process in large zeolite ZSM-5 crystals. Correlation of polarized light dependent UV-Vis absorption spectra with confocal fluorescence emission spectra in the 400–750 nm region

Prophyrin identification by 3rd derivative UV/VIS spectroscopy

International Nuclear Information System (INIS)

Freeman, D.H.; Saint Martin, D.C.; Boreham, C.J.

1992-01-01

This patent describes the Soret band wavelength of nickel and vanadyl porphyrins λ Soret, which identifies etic DPEP/di-DPEP, propano and butano structure types. The approach is based upon routine diode array uv/vis spectra taken to their 3rd derivative. an interpolated zero crossing gives λ max within 0.1 nm. Accordingly, reference spectral properties of 27 well characterized metalloporphyrins were determined. When λSoret, λα and λβ and molecular mass data were combined, each of the DPEP and di-DPEP nickel complexes were distinct. In addition, λSoret was able to classify nickel etioporphyrins according to the number of beta hydrogens. To illustrate the many possible applications, two substances were isolated by HPLC from a Messel Shale extract based on known HPLC C18 retentions. Comparison of wavelength and mass between isolated and reference counterparts showed precise agreement. Thus uv/vic spectroscopy helps to classify porphyrin structure, and to facilitate identification by matching to reference data

UV-VIS-spectroscopical investigations of the green solutions of nitrogen triiodide-1-pyridine in pyridine

International Nuclear Information System (INIS)

Kerbachi, R.; Minkwitz, R.; Engelhardt, U.

1984-01-01

Solid, crystalline nitrogen triiodide-1-pyridine has a polymeric structure similar to that of nitrogen triiodide-1-ammonia consisting of NI 4 tetrahedra linked to chains by common vertices. The solubility of both compounds in liquid ammonia is accomplished by a degradation of the chains involving protolysis equilibria with monoiodamine. UV-VIS-spectra of the green solutions of NI 3 pyridine in the aprotic solvent pyridine between -30 and -16 0 C and Raman-spectra of these solutions at -30 0 C or quenched with liquid nitrogen at -196 0 C show, that the chains are retained here at least to some extent. The solutions are instable even at low temperatures and decompose in a first order reaction yielding nitrogen and iodine. The halflife period at -16 0 C is 5 hours, at -30 0 C 20 hours. (author)

Microenvironmental pH measurement during sodium naproxenate dissolution in acidic medium by UV/vis imaging

DEFF Research Database (Denmark)

Ostergaard, Jesper; Jensen, Henrik; Larsen, Susan W

2014-01-01

Variable dissolution from sodium salts of drugs containing a carboxylic acid group after passing the acidic environment of the stomach may affect oral bioavailability. The aim of the present proof of concept study was to investigate pH effects in relation to the dissolution of sodium naproxenate...... in 0.01M hydrochloric acid. For this purpose a UV/vis imaging-based approach capable of measuring microenvironmental pH in the vicinity of the solid drug compact as well as monitoring drug dissolution was developed. Using a pH indicating dye real-time spatially resolved measurement of pH was achieved....... Sodium naproxenate, can significantly alter the local pH of the dissolution medium, is eventually neutralized and precipitates as the acidic species naproxen. The developed approach is considered useful for detailed studies of pH dependent dissolution phenomena in dissolution testing....

Method development and validation of potent pyrimidine derivative by UV-VIS spectrophotometer.

Science.gov (United States)

Chaudhary, Anshu; Singh, Anoop; Verma, Prabhakar Kumar

2014-12-01

A rapid and sensitive ultraviolet-visible (UV-VIS) spectroscopic method was developed for the estimation of pyrimidine derivative 6-Bromo-3-(6-(2,6-dichlorophenyl)-2-(morpolinomethylamino) pyrimidine4-yl) -2H-chromen-2-one (BT10M) in bulk form. Pyrimidine derivative was monitored at 275 nm with UV detection, and there is no interference of diluents at 275 nm. The method was found to be linear in the range of 50 to 150 μg/ml. The accuracy and precision were determined and validated statistically. The method was validated as a guideline. The results showed that the proposed method is suitable for the accurate, precise, and rapid determination of pyrimidine derivative. Graphical Abstract Method development and validation of potent pyrimidine derivative by UV spectroscopy.

UV-Vis spectroscopy of tyrosine side-groups in studies of protein structure. Part 2: selected applications.

Science.gov (United States)

Antosiewicz, Jan M; Shugar, David

2016-06-01

In Part 2 we discuss application of several different types of UV-Vis spectroscopy, such as normal, difference, and second-derivative UV absorption spectroscopy, fluorescence spectroscopy, linear and circular dichroism spectroscopy, and Raman spectroscopy, of the side-chain of tyrosine residues in different molecular environments. We review the ways these spectroscopies can be used to probe complex protein structures.

Combined In Situ Illumination-NMR-UV/Vis Spectroscopy: A New Mechanistic Tool in Photochemistry.

Science.gov (United States)

Seegerer, Andreas; Nitschke, Philipp; Gschwind, Ruth M

2018-06-18

Synthetic applications in photochemistry are booming. Despite great progress in the development of new reactions, mechanistic investigations are still challenging. Therefore, we present a fully automated in situ combination of NMR spectroscopy, UV/Vis spectroscopy, and illumination to allow simultaneous and time-resolved detection of paramagnetic and diamagnetic species. This optical fiber-based setup enables the first acquisition of combined UV/Vis and NMR spectra in photocatalysis, as demonstrated on a conPET process. Furthermore, the broad applicability of combined UVNMR spectroscopy for light-induced processes is demonstrated on a structural and quantitative analysis of a photoswitch, including rate modulation and stabilization of transient species by temperature variation. Owing to the flexibility regarding the NMR hardware, temperature, and light sources, we expect wide-ranging applications of this setup in various research fields. © 2018 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Application of ZnO Nanoparticle as Sulphide Gas Sensor Using UV/VIS/NIR-Spectrophotometer

International Nuclear Information System (INIS)

Juliasih, N; Buchari; Noviandri, I

2017-01-01

The nanoparticle of metal oxides has great unique characteristics that applicable to the wide industrial as sensors and catalysts for reducing environmental pollution. Sulphide gas monitors and detectors are required for assessing safety aspects, due to its toxicity level. A thin film of ZnO as the sulphide gas sensor was synthesised by the simple method of chemical liquid deposition with variation of annealing temperature from 200 ºC to 500 ºC, and characterised by Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), and UV/VIS/NIR-Spectrophotometer. Characterization studies showed nanoparticle size from the range 62 – 92 nm of diameters. The application this ZnO thin film to sulfide gas, detected by UV/VIS/NIR Spectrophotometer with diffuse reflectance, showed specific chemical reaction by the shifting of maximum % Reflectance peak. The gas sensing using this method is applicable at room. (paper)

Coupling Reagent for UV/vis Absorbing Azobenzene-Based Quantitative Analysis of the Extent of Functional Group Immobilization on Silica.

Science.gov (United States)

Choi, Ra-Young; Lee, Chang-Hee; Jun, Chul-Ho

2018-05-18

A methallylsilane coupling reagent, containing both a N-hydroxysuccinimidyl(NHS)-ester group and a UV/vis absorbing azobenzene linker undergoes acid-catalyzed immobilization on silica. Analysis of the UV/vis absorption band associated with the azobenzene group in the adduct enables facile quantitative determination of the extent of loading of the NHS groups. Reaction of NHS-groups on the silica surface with amine groups of GOx and rhodamine can be employed to generate enzyme or dye-immobilized silica for quantitative analysis.

UV-vis spectral property of a multi-hydroxyl Schiff-base derivative and its colorimetric response to some special metal ions.

Science.gov (United States)

Xing, Lin; Zheng, Xiaoyu; Sun, Wenyu; Yuan, Hua; Hu, Lei; Yan, Zhengquan

2018-06-05

A multi-hydroxyl Schiff-base derivative, N-2'-hydroxyl-1'-naphthyl methylene-2-amino phenol (HNMAP), was synthesized and characterized by FTIR, 1 H NMR and UV-vis spectroscopy. It was noted to find there was great effect for solvent and pH on the UV-vis spectroscopy of HNMAP. Especially, some metal ions could make its UV-vis spectra changed regularly with different time-resolved effects. For example, a real-time and multi-wavelength response to Fe 2+ at 520 nm, 466 nm and 447 nm and a quite slow one about 26 min to Fe 3+ at 447 nm and 466 nm, respectively. Under the optimized conditions, the changes in the corresponding absorption intensities at above wavelengths were in proportion to c Fe 2+ or c Fe 3+ during respectively partitioned linear ranges, which realized to quantitatively detect Fe 2+ or Fe 3+ with a large linear range more than two orders of magnitude. A 1:1 complex mode for HNMAP-Fe 2+ and 1:2 for HNMAP-Fe 3+ were proposed from UV-vis spectral titration and Job's plot. HNMAP would be a potential sensor for colorimetric detection of Fe 2+ and Fe 3+ in practice. Copyright © 2018 Elsevier B.V. All rights reserved.

Differentiation of tea varieties using UV-Vis spectra and pattern recognition techniques

Science.gov (United States)

Palacios-Morillo, Ana; Alcázar, Ángela.; de Pablos, Fernando; Jurado, José Marcos

2013-02-01

Tea, one of the most consumed beverages all over the world, is of great importance in the economies of a number of countries. Several methods have been developed to classify tea varieties or origins based in pattern recognition techniques applied to chemical data, such as metal profile, amino acids, catechins and volatile compounds. Some of these analytical methods become tedious and expensive to be applied in routine works. The use of UV-Vis spectral data as discriminant variables, highly influenced by the chemical composition, can be an alternative to these methods. UV-Vis spectra of methanol-water extracts of tea have been obtained in the interval 250-800 nm. Absorbances have been used as input variables. Principal component analysis was used to reduce the number of variables and several pattern recognition methods, such as linear discriminant analysis, support vector machines and artificial neural networks, have been applied in order to differentiate the most common tea varieties. A successful classification model was built by combining principal component analysis and multilayer perceptron artificial neural networks, allowing the differentiation between tea varieties. This rapid and simple methodology can be applied to solve classification problems in food industry saving economic resources.

Improved analysis of Monascus pigments based on their pH-sensitive UV-Vis absorption and reactivity properties.

Science.gov (United States)

Shi, Kan; Chen, Gong; Pistolozzi, Marco; Xia, Fenggeng; Wu, Zhenqiang

2016-09-01

Monascus pigments, a mixture of azaphilones mainly composed of red, orange and yellow pigments, are usually prepared in aqueous ethanol and analysed by ultraviolet-visible (UV-Vis) spectroscopy. The pH of aqueous ethanol used during sample preparation and analysis has never been considered a key parameter to control; however, this study shows that the UV-Vis spectra and colour characteristics of the six major pigments are strongly influenced by the pH of the solvent employed. In addition, the increase of solvent pH results in a remarkable increase of the amination reaction of orange pigments with amino compounds, and at higher pH (≥ 6.0) a significant amount of orange pigment derivatives rapidly form. The consequent impact of these pH-sensitive properties on pigment analysis is further discussed. Based on the presented results, we propose that the sample preparation and analysis of Monascus pigments should be uniformly performed at low pH (≤ 2.5) to avoid variations of UV-Vis spectra and the creation of artefacts due to the occurrence of amination reactions, and ensure an accurate analysis that truly reflects pigment characteristics in the samples.

H-aggregate analysis of P3HT thin films-Capability and limitation of photoluminescence and UV/Vis spectroscopy.

Science.gov (United States)

Ehrenreich, Philipp; Birkhold, Susanne T; Zimmermann, Eugen; Hu, Hao; Kim, Kwang-Dae; Weickert, Jonas; Pfadler, Thomas; Schmidt-Mende, Lukas

2016-09-01

Polymer morphology and aggregation play an essential role for efficient charge carrier transport and charge separation in polymer-based electronic devices. It is a common method to apply the H-aggregate model to UV/Vis or photoluminescence spectra in order to analyze polymer aggregation. In this work we present strategies to obtain reliable and conclusive information on polymer aggregation and morphology based on the application of an H-aggregate analysis on UV/Vis and photoluminescence spectra. We demonstrate, with P3HT as model system, that thickness dependent reflection behavior can lead to misinterpretation of UV/Vis spectra within the H-aggregate model. Values for the exciton bandwidth can deviate by a factor of two for polymer thicknesses below 150 nm. In contrast, photoluminescence spectra are found to be a reliable basis for characterization of polymer aggregation due to their weaker dependence on the wavelength dependent refractive index of the polymer. We demonstrate this by studying the influence of surface characteristics on polymer aggregation for spin-coated thin-films that are commonly used in organic and hybrid solar cells.

Validation of quantitative analysis method for triamcinolone in ternary complexes by UV-Vis spectrophotometry

Directory of Open Access Journals (Sweden)

GEORGE DARLOS A. AQUINO

2011-06-01

Full Text Available Triamcinolone (TRI, a drug widely used in the treatment of ocular inflammatory diseases, is practically insoluble in water, which limits its use in eye drops. Cyclodextrins (CDs have been used to increase the solubility or dissolution rate of drugs. The purpose of the present study was to validate a UV-Vis spectrophotometric method for quantitative analysis of TRI in inclusion complexes with beta-cyclodextrin (B-CD associated with triethanolamine (TEA (ternary complex. The proposed analytical method was validated with respect to the parameters established by the Brazilian regulatory National Agency of Sanitary Monitoring (ANVISA. The analytical measurements of absorbance were made at 242nm, at room temperature, in a 1-cm path-length cuvette. The precision and accuracy studies were performed at five concentration levels (4, 8, 12, 18 and 20μg.mL-1. The B-CD associated with TEA did not provoke any alteration in the photochemical behavior of TRI. The results for the measured analytical parameters showed the success of the method. The standard curve was linear (r2 > 0.999 in the concentration range from 2 to 24 μg.mL-1. The method achieved good precision levels in the inter-day (relative standard deviation-RSD <3.4% and reproducibility (RSD <3.8% tests. The accuracy was about 80% and the pH changes introduced in the robustness study did not reveal any relevant interference at any of the studied concentrations. The experimental results demonstrate a simple, rapid and affordable UV-Vis spectrophotometric method that could be applied to the quantitation of TRI in this ternary complex. Keywords: Validation. Triamcinolone. Beta-cyclodextrin. UV- Vis spectrophotometry. Ternary complexes. RESUMO Validação de método de análise quantitativa para a triancinolona a partir de complexo ternário por espectrofotometria de UV-Vis A triancinolona (TRI é um fármaco amplamente utilizado no tratamento de doenças inflamatórias do globo ocular e �

Co(II) Coordination in Prokaryotic Zinc Finger Domains as Revealed by UV-Vis Spectroscopy

Science.gov (United States)

Sivo, Valeria; D'Abrosca, Gianluca; Russo, Luigi; Iacovino, Rosa; Pedone, Paolo Vincenzo; Fattorusso, Roberto

2017-01-01

Co(II) electronic configuration allows its use as a spectroscopic probe in UV-Vis experiments to characterize the metal coordination sphere that is an essential component of the functional structure of zinc-binding proteins and to evaluate the metal ion affinities of these proteins. Here, exploiting the capability of the prokaryotic zinc finger to use different combinations of residues to properly coordinate the structural metal ion, we provide the UV-Vis characterization of Co(II) addition to Ros87 and its mutant Ros87_C27D which bears an unusual CysAspHis2 coordination sphere. Zinc finger sites containing only one cysteine have been infrequently characterized. We show for the CysAspHis2 coordination an intense d-d transition band, blue-shifted with respect to the Cys2His2 sphere. These data complemented by NMR and CD data demonstrate that the tetrahedral geometry of the metal site is retained also in the case of a single-cysteine coordination sphere. PMID:29386985

Spectroscopic (vibrational, NMR and UV-vis.) and quantum chemical investigations on 4-hexyloxy-3-methoxybenzaldehyde.

Science.gov (United States)

Abbas, Ashgar; Gökce, Halil; Bahçeli, Semiha

2016-01-05

In this study, the 4-hexyloxy-3-methoxybenzaldehyde compound as one of the derivatives of vanillin which is a well known flavoring agent, C14H20O3, has been investigated by experimentally and extensively utilizing density functional theory (DFT) at the B3LYP/6-311++G(d,p) level. In this context, the optimized geometry, vibrational frequencies, (1)H and (13)C NMR chemical shifts, UV-vis. (in gas phase and in methanol solvent) spectra, HOMO-LUMO analysis, molecular electrostatic potential (MEP), thermodynamic parameters and atomic charges of 4-hexyloxy-3-methoxybenzaldehyde have been calculated. In addition, theoretically predicted IR, Raman and UV-vis. (in gas phase and in methanol solvent) spectra of the mentioned molecule have been constructed. The results calculated were compared with the experimental data. Copyright © 2015 Elsevier B.V. All rights reserved.

On the role of visible radiation in ozone profile retrieval from nadir UV/VIS satellite measurements: An experiment with neural network algorithms inverting SCIAMACHY data

International Nuclear Information System (INIS)

Sellitto, P.; Di Noia, A.; Del Frate, F.; Burini, A.; Casadio, S.; Solimini, D.

2012-01-01

Theoretical evidence has been given on the role of visible (VIS) radiation in enhancing the accuracy of ozone retrievals from satellite data, especially in the troposphere. However, at present, VIS is not being systematically used together with ultraviolet (UV) measurements, even when possible with one single instrument, e.g., the SCanning Imaging Absorption spectroMeter for Atmospheric CartograpHY (SCIAMACHY). Reasons mainly reside in the defective performance of optimal estimation and regularization algorithms caused by inaccurate modeling of VIS interaction with aerosols or clouds, as well as in inconsistent intercalibration between UV and VIS measurements. Here we intend to discuss the role of VIS radiation when it feeds a retrieval algorithm based on Neural Networks (NNs) that does not need a forward radiative transfer model and is robust with respect to calibration errors. The NN we designed was trained with a set of ozonesondes (OSs) data and tested over an independent set of OS measurements. We compared the ozone concentration profiles retrieved from UV-only with those retrieved from UV plus VIS nadir data taken by SCIAMACHY. We found that VIS radiation was able to yield more than 10% increase of accuracy and to substantially reduce biases of retrieved profiles at tropospheric levels.

Preparation of re-usable photocatalytic filter for degradation of Malachite Green dye under UV and vis-irradiation

International Nuclear Information System (INIS)

Sayilkan, F.; Asiltuerk, M.; Tatar, P.; Kiraz, N.; Arpac, E.; Sayilkan, H.

2007-01-01

Sn 4+ doped and undoped nano-TiO 2 particles easily dispersed in water were synthesized without using organic solvent by hydrothermal process. Nanostructure-TiO 2 based thin films were prepared on flyswatter substrate, made with stainless steel, by dip-coating technique. The structure, surface and optical properties of the particles and thin films were characterized by element analysis and XRD, BET, SEM and UV/vis/NIR techniques. The photocatalytic performance of the films were tested for degradation of Malachite Green dye in solution under UV and vis-lights. The results showed that the coated flyswatter has a very high photocatalytic performance for the photodegradation of Malachite Green irradiated with UV and vis-lights. The results also proved that the hydrothermally synthesized nano-TiO 2 particles are fully anatase crystalline form and are easily dispersed in water, the coated surfaces are hydrophilic, and the doping of transition metal ion efficiently improved the degradation performance of TiO 2 -coated flyswatter. The photocatalytic performances determined at both irradiation conditions were very good and were almost similar to each other for Sn 4+ doped TiO 2 -coated flyswatter and it can be repeatedly used with increasing photocatalytic activity compared to undoped TiO 2 -coated flyswatter

A reversible conductivity modulation of azobenzene-based ionic liquids in aqueous solutions using UV/vis light.

Science.gov (United States)

Li, Zhiyong; Yuan, Xiaoqing; Feng, Ying; Chen, Yongkui; Zhao, Yuling; Wang, Huiyong; Xu, Qingli; Wang, Jianji

2018-05-09

Photo-induced conductivity modulation of stimuli-responsive materials is of great importance from the viewpoint of fundamental research and technology. In this work, 5 new kinds of azobenzene-based photo-responsive ionic liquids were synthesized and characterized, and UV/vis light modulation of their conductivity was investigated in an aqueous solution. The factors affecting the conductivity modulation of the photo-responsive fluids, such as photo-isomerization efficiency, photo-regulation aggregation, concentration and chemical structure of the ionic liquids, were examined systematically. It was found that the conductivity of the ionic liquids in water exhibited a significant increase upon UV light irradiation and the ionic liquids with a shorter alkyl spacer in the cation showed a more remarkable photo-induced conductivity enhancement with a maximum increase of 150%. In addition, the solution conductivity was restored (or very close) to the initial value upon an alternative irradiation with visible light. Thus, the solution conductivity can be modulated using alternative irradiation with UV and visible light. Although the reversible photo-isomerization of the azobenzene group under UV/vis irradiation is the origin of the conductivity modulation, the photo-regulated aggregation of the ionic liquid in water is indispensable for the maximum degree of conductivity modulation because UV irradiation can weaken, even break the aggregated cis-isomers of the ionic liquids in an aqueous solution.

Efficient all solid-state UV source for satellite-based lidar applications.

Energy Technology Data Exchange (ETDEWEB)

Armstrong, Darrell Jewell; Smith, Arlee Virgil

2003-07-01

A satellite-based UV-DIAL measurement system would allow continuous global monitoring of ozone concentration in the upper atmosphere. However such systems remain difficult to implement because aerosol-scattering return signals for satellite-based lidars are very weak. A suitable system must produce high-energy UV pulses at multiple wavelengths with very high efficiency. For example, a nanosecond system operating at 10 Hz must generate approximately 1 J per pulse at 308-320 nm. An efficient space-qualified wavelength-agile system based on a single UV source that can meet this requirement is probably not available using current laser technology. As an alternative, we're pursuing a multi-source approach employing all-solid-state modules that individually generate 300-320 nm light with pulse energies in the range of 50-200 mJ, with transform-limited bandwidths and good beam quality. Pulses from the individual sources can be incoherently summed to obtain the required single-pulse energy. These sources use sum-frequency mixing of the 532 nm second harmonic of an Nd:YAG pump laser with 731-803 nm light derived from a recently-developed, state-of-the-art, nanosecond optical parametric oscillator. Two source configurations are under development, one using extra-cavity sum-frequency mixing, and the other intra-cavity sum-frequency mixing. In either configuration, we hope to obtain sum-frequency mixing efficiency approaching 60% by carefully matching the spatial and temporal properties of the laser and OPO pulses. This ideal balance of green and near-IR photons requires an injection-seeded Nd:YAG pump-laser with very high beam quality, and an OPO exhibiting unusually high conversion efficiency and exceptional signal beam quality. The OPO employs a singly-resonant high-Fresnel-number image-rotating self-injection-seeded nonplanar-ring cavity that achieves pump depletion > 65% and produces signal beams with M{sup 2} {approx} 3 at pulse energies exceeding 50 mJ. Pump beam

ANALISA FLAVONOID DARI EKSTRAK ETANOL 96% KULIT BUAH OKRA MERAH (Abelmoschus esculentus L. Moench SECARA KROMATOGRAFI LAPIS TIPIS DAN SPEKTROFOTOMETRI UV-VIS

Directory of Open Access Journals (Sweden)

Nia Lisnawati

2016-03-01

Full Text Available Has done research on flavonoids Analysis of Ethanol Extract 96% Fruit Leather Red Okra In Thin Layer Chromatography and Spectrophotometer UV-Vis. The purpose of this study was to analyze the content of the fruit skin red okra (Abelmoschus esculentus L. Moench by using the method of thin layer chromatography (TLC under UV light and spectrophotometry UV-Vis. Reference standards used in this study is the Standard Solution Routine Quercetin. The results of the research that has been done by the method of thin layer chromatography obtained Rf values of 0.81 and produces the color orange. And the results of research conducted by spectrophotometry UV-Vis method obtained 333,117 mg.L-1 or 421,629 mg.kg-1 or 0,84339 %. The conclusion from this study is that the 96% ethanol extract of the fruit leather red okra (Abelmoschus esculentus L. Moench positive (+ contains flavonoids with levels of 0,84339 %.

Determination of the electronic structure and UV-Vis absorption properties of (Na2-xCux)Ta4O11 from first-principle calculations

KAUST Repository

Harb, Moussab

2013-08-29

Density functional theory (DFT) and density functional perturbation theory (DFPT) were applied to study the structural, electronic, and optical properties of a (Na2-xCux)Ta4O11 solid solution to accurately calculate the band gap and to predict the optical transitions in these materials using the screened coulomb hybrid (HSE06) exchange-correlation formalism. The calculated density of states showed excellent agreement with UV-vis diffuse reflectance spectra predicting a significant red-shift of the band gap from 4.58 eV (calculated 4.94 eV) to 2.76 eV (calculated 2.60 eV) as copper content increased from 0 to 83.3%. The band gap narrowing in these materials, compared to Na2Ta4O11, results from the incorporation of new occupied electronic states, which are strongly localized on the Cu 3d orbitals, and is located within 2.16-2.34 eV just above the valence band of Na2Ta4O11. These new occupied states, however, possess an electronic character localized on Cu, which makes hole mobility limited in the semiconductor. © 2013 American Chemical Society.

A comparative approach of methylparaben photocatalytic degradation assisted by UV-C, UV-A and Vis radiations.

Science.gov (United States)

Doná, Giovanna; Dagostin, João Luiz Andreoti; Takashina, Thiago Atsushi; de Castilhos, Fernanda; Igarashi-Mafra, Luciana

2018-05-01

Due to the widespread use of methylparaben (MEP) and its high chemical stability, it can be found in wastewater treatment plants and can act as an endocrine disrupting compound. In this study, the photocatalytic degradation and mineralization of MEP solutions were evaluated under UV-A, UV-C and Vis radiations in the presence of the photocatalyst TiO 2 . In this sense, the effects of the catalyst load, pH and MEP initial concentration were studied. Remarkably higher reaction rates and total photodegradation were achieved in systems assisted by UV-C radiation. The complete degradation was achieved after 60 min of reaction using the MEP concentration of 30 mg L -1 at pH 9 and 500 mg L -1 TiO 2 . The experimental data apparently followed a Langmuir-Hinshelwood kinetic model, which could predict 88-98% of the reaction behavior. For the best photodegradation condition, the model predicted an apparent reaction rate constant (k app ) equal to 0.0505 min -1 and an initial reaction rate of 1.5641 mg (L min) -1 . Mineralization analyses showed high removal for MEP and derived compounds from the initial solution when using UV-C after 90 min of reaction. The lower toxicity was also confirmed by in vivo tests using MEP solutions previously treated by photocatalysis.

Rationalization of the Color Properties of Fluorescein in the Solid State: A Combined Computational and Experimental Study.

Science.gov (United States)

Arhangelskis, Mihails; Eddleston, Mark D; Reid, David G; Day, Graeme M; Bučar, Dejan-Krešimir; Morris, Andrew J; Jones, William

2016-07-11

Fluorescein is known to exist in three tautomeric forms defined as quinoid, zwitterionic, and lactoid. In the solid state, the quinoid and zwitterionic forms give rise to red and yellow materials, respectively. The lactoid form has not been crystallized pure, although its cocrystal and solvate forms exhibit colors ranging from yellow to green. An explanation for the observed colors of the crystals is found using a combination of UV/Vis spectroscopy and plane-wave DFT calculations. The role of cocrystal coformers in modifying crystal color is also established. Several new crystal structures are determined using a combination of X-ray and electron diffraction, solid-state NMR spectroscopy, and crystal structure prediction (CSP). The protocol presented herein may be used to predict color properties of materials prior to their synthesis. © 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Probing the Behaviors of Gold Nanorods in Metastatic Breast Cancer Cells Based on UV-vis-NIR Absorption Spectroscopy

Science.gov (United States)

Zhang, Weiqi; Ji, Yinglu; Meng, Jie; Wu, Xiaochun; Xu, Haiyan

2012-01-01

In this work, behaviors of positively-charged AuNRs in a highly metastatic tumor cell line MDA-MB-231 are examined based on UV-vis-NIR absorption spectroscopy in combination with inductively coupled plasma mass spectrometry (ICP-MS), transmission electron microscopy (TEM) and dark-field microscopic observation. It is found that characteristic surface plasmon resonance (SPR) peaks of AuNRs can be detected using spectroscopic method within living cells that have taken up AuNRs. The peak area of transverse SPR band is shown to be proportionally related to the amount of AuNRs in the cells determined with ICP-MS, which suggests a facile and real time quantification method for AuNRs in living cells. The shape of longitudinal SPR band in UV-vis-NIR spectrum reflects the aggregation state of AuNRs in the cells during the incubation period, which is proved by TEM and microscopic observations. Experimental results reveal that AuNRs are internalized by the cells rapidly; the accumulation, distribution and aggregation of AuNRs in the cells compartments are time and dose dependent. The established spectroscopic analysis method can not only monitor the behaviors of AuNRs in living cells but may also be helpful in choosing the optimum laser stimulation wavelength for anti-tumor thermotherapy. PMID:22384113

UV-visible spectroscopy as an alternative to liquid chromatography for determination of everolimus in surfactant-containing dissolution media: a useful approach based on solid-phase extraction.

Science.gov (United States)

Kamberi, Marika; Tran, Thu-Ngoc

2012-11-01

High-throughput 96-well solid phase extraction (SPE) plate with C-18 reversed phase sorbent followed by UV-visible (UV-Vis) microplate reader was applied to the analysis of hydrophobic drugs in surfactant-containing dissolution media, which are often used to evaluate the in-vitro drug release of drug eluting stents (DES). Everolimus and dissolution medium containing Triton X-405 were selected as representatives, and the appropriate SPE conditions (adsorption, washing and elution) were investigated to obtain a practical and reliable sample clean-up. It was shown that the developed SPE procedure was capable of removing interfering components (Triton X-405 and its impurities), allowing for an accurate automated spectrophotometric analysis to be performed. The proposed UV-Vis spectrophotometric method yielded equivalent results compared to a classical LC analysis method. Linear regression analysis indicated that both methods have the ability to obtain test results that are directly proportional to the concentration of analyte in the sample within the selected range of 1.0-10 μg/ml for everolimus, with a coefficient of correlation (r(2)) value of >0.998 and standard deviation of the residuals (Syx) of UV-Vis spectrophotometric method and from 98 to 102 for the HPLC method, respectively. The 95% CI of the mean recovery for the UV-Vis spectrophotometric method was 99-102% and for the HPLC method was 99-101%. No statistical difference was found between the mean recoveries of the methods (p=0.42). Hence the methods are free from interference due to Triton and other chemicals present in the dissolution medium. The variation in the amount of everolimus estimated by UV-Vis spectrophotometric and HPLC methods was ≤3.5%, and the drug release profiles obtained by both methods were found to be equivalent by evaluation with two-one-sided t-test (two-tailed, p=0.62; mean of differences, 0.17; 95% CI, 0.62-0.96) and similarity factor f2 (f2 value, 87). The excellent conformity of

Study of interaction between ionic liquids and orange G in aqueous solution with UV-vis spectroscopy and conductivity meter.

Science.gov (United States)

Zha, Jin-Ping; Zhu, Meng-Ting; Qin, Li; Wang, Xin-Hong

2018-05-05

The interactions between Orange G (OG) with three kinds of ionic liquid surfactants (C 10 mimBF 4 , C 12 mimBF 4 , C 16 mimBF 4 ) and CTAB were studied with UV-Vis spectra and conductivity measurements. The systematic changes in UV-Vis spectra with an increase of carbon-chain length may be observed in presence of OG. They correspond to CMC of every system, respectively, and the CMCs of four systems have exhibit the decrease of CMCs compared to pure surfactant. The binding constants are calculated from the results of conductivity measurements in the order of C 16 mimBF 4 >CTAB>C 12 mimBF 4 >C 10 mimBF 4 . Furthermore, system behaviors presented significant association of complex formation and micelles formation, i.e. the change in UV-Vis spectra before and after the formation of micelles in mixed systems. In addition, Fourier-transform infrared (FT-IR) spectroscopy and 1 H NMR analysis further confirmed that the complexes are formed by hydrogen bond and van der Waal force. These findings could provide scientific guidance for extraction and separation of dyes. Copyright © 2018 Elsevier B.V. All rights reserved.

Study of interaction between ionic liquids and orange G in aqueous solution with UV-vis spectroscopy and conductivity meter

Science.gov (United States)

Zha, Jin-Ping; Zhu, Meng-Ting; Qin, Li; Wang, Xin-Hong

2018-05-01

The interactions between Orange G (OG) with three kinds of ionic liquid surfactants (C10mimBF4, C12mimBF4, C16mimBF4) and CTAB were studied with UV-Vis spectra and conductivity measurements. The systematic changes in UV-Vis spectra with an increase of carbon-chain length may be observed in presence of OG. They correspond to CMC of every system, respectively, and the CMCs of four systems have exhibit the decrease of CMCs compared to pure surfactant. The binding constants are calculated from the results of conductivity measurements in the order of C16mimBF4 > CTAB > C12mimBF4 > C10mimBF4. Furthermore, system behaviors presented significant association of complex formation and micelles formation, i.e. the change in UV-Vis spectra before and after the formation of micelles in mixed systems. In addition, Fourier-transform infrared (FT-IR) spectroscopy and 1H NMR analysis further confirmed that the complexes are formed by hydrogen bond and van der Waal force. These findings could provide scientific guidance for extraction and separation of dyes.

ESTIMACIÓN DEL EXPONENTE DE HURST Y DIMENSIÓN FRACTAL PARA EL ANÁLISIS DE SERIES DE TIEMPO DE ABSORBANCIA UV-VIS

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Leonardo Plazas Nossa

2014-01-01

Full Text Available El objetivo de este trabajo es estimar el exponente o parámetro de Hurst y la dimensión fractal para el análisis de series de tiempo de espectrometría UV-Vis, utilizando el análisis de componentes principales PCA (Principal Component Analysis. El análisis se realiza para comprender si las series de tiempo de absorbancia UV-Vis son persistentes, anti-persistentes, determinísticas o si son ruido blanco. Se utilizaron tres diferentes series de tiempo de absorbancia UV-Vis para tres diferentes sitios de estudio: (i Planta de tratamiento de aguas residuales Salitre (PTAR en Bogotá; (ii Estación elevadora de Gibraltar en Bogotá (EEG; y (iii Planta de tratamiento de aguas residuales San Fernando (PTAR en Itagüí (sur de Medellín. Cada una de las series de tiempo tiene igual número de muestras (5705. Se redujo la dimensionalidad de los espectros de absorbancia, dada su alta correlación, con PCA y se utilizó para cada sitio de estudio la primera componente principal. Esta componente principal explicó entre el 82% al 94% de la variabilidad para los tres sitios de estudio. Se determinaron los exponentes de Hurst: (i 0.8 para PTAR Salitre; (ii 0.85 para EEG; y (iii 0.89 para PTAR San Fernando. A partir de los valores de los exponentes de Hurst se determinan las dimensiones fractales para las tres series de tiempo de absorbancia UV-Vis en los tres sitios de estudio y se obtiene en promedio una dimensión fractal de 1153. Las tres series de tiempo de absorbancia UV-Vis son persistentes y con alta auto-similitud, dado que el exponente de Hurst es mayor a 0.5.

Discrimination of Apple Liqueurs (Nalewka) Using a Voltammetric Electronic Tongue, UV-Vis and Raman Spectroscopy.

Science.gov (United States)

Śliwińska, Magdalena; Garcia-Hernandez, Celia; Kościński, Mikołaj; Dymerski, Tomasz; Wardencki, Waldemar; Namieśnik, Jacek; Śliwińska-Bartkowiak, Małgorzata; Jurga, Stefan; Garcia-Cabezon, Cristina; Rodriguez-Mendez, Maria Luz

2016-10-09

The capability of a phthalocyanine-based voltammetric electronic tongue to analyze strong alcoholic beverages has been evaluated and compared with the performance of spectroscopic techniques coupled to chemometrics. Nalewka Polish liqueurs prepared from five apple varieties have been used as a model of strong liqueurs. Principal Component Analysis has demonstrated that the best discrimination between liqueurs prepared from different apple varieties is achieved using the e-tongue and UV-Vis spectroscopy. Raman spectra coupled to chemometrics have not been efficient in discriminating liqueurs. The calculated Euclidean distances and the k-Nearest Neighbors algorithm (kNN) confirmed these results. The main advantage of the e-tongue is that, using PLS-1, good correlations have been found simultaneously with the phenolic content measured by the Folin-Ciocalteu method (R² of 0.97 in calibration and R² of 0.93 in validation) and also with the density, a marker of the alcoholic content method (R² of 0.93 in calibration and R² of 0.88 in validation). UV-Vis coupled with chemometrics has shown good correlations only with the phenolic content (R² of 0.99 in calibration and R² of 0.99 in validation) but correlations with the alcoholic content were low. Raman coupled with chemometrics has shown good correlations only with density (R² of 0.96 in calibration and R² of 0.85 in validation). In summary, from the three holistic methods evaluated to analyze strong alcoholic liqueurs, the voltammetric electronic tongue using phthalocyanines as sensing elements is superior to Raman or UV-Vis techniques because it shows an excellent discrimination capability and remarkable correlations with both antioxidant capacity and alcoholic content-the most important parameters to be measured in this type of liqueurs.

Inline UV-Vis spectroscopy to monitor and optimize cleaning-in-place (CIP) of whey filtration plants

DEFF Research Database (Denmark)

Berg, Thilo Heinz Alexander; Ottosen, Niels; van der Berg, Franciscus Winfried J.

2017-01-01

used for every day. We investigated the capability of inline UV-Vis spectroscopy to elucidate the dynamics of CIP of membrane filtration plants as a gateway to control and optimize the process. For this investigation aged membranes that had been used for industrial ultrafiltration of whey were...

Experimental and theoretical studies on IR, Raman, and UV-Vis spectra of quinoline-7-carboxaldehyde.

Science.gov (United States)

Kumru, M; Küçük, V; Kocademir, M; Alfanda, H M; Altun, A; Sarı, L

2015-01-05

Spectroscopic properties of quinoline-7-carboxaldehyde (Q7C) have been studied in detail both experimentally and theoretically. The FT-IR (4000-50 cm(-1)), FT-Raman (4000-50 cm(-1)), dispersive-Raman (3500-50 cm(-1)), and UV-Vis (200-400 nm) spectra of Q7C were recorded at room temperature (25 °C). Geometry parameters, potential energy surface about CCH(O) bond, harmonic vibrational frequencies, IR and Raman intensities, UV-Vis spectrum, and thermodynamic characteristics (at 298.15K) of Q7C were computed at Hartree-Fock (HF) and density functional B3LYP levels employing the 6-311++G(d,p) basis set. Frontier molecular orbitals, molecular electrostatic potential, and Mulliken charge analyses of Q7C have also been performed. Q7C has two stable conformers that are energetically very close to each other with slight preference to the conformer that has oxygen atom of the aldehyde away from the nitrogen atom of the quinoline. Copyright © 2014 Elsevier B.V. All rights reserved.

Study of the reaction between Uranium(III) and Lanthanide oxide by using the UV-VIS spectrophotometer

International Nuclear Information System (INIS)

Kim, Tack-Jin; Cho, Young-Hwan; Choi, In-Kyu; Choi, Kwang-Soon; Jee, Kwang-Yong

2006-01-01

Recently, ionic melts have become attractive reaction media in many fields. Molten salt based electrochemical processes have been proposed as a promising method for future nuclear programs and more specifically for spent fuel processing. Molten alkaline chloride based melts are considered as a promising reaction media. For this, it is interesting to understand the chemical nature of the actinides and lanthanides in high-temperature melt. Some spectroscopy provides essential information on the exact nature of f-block elements LiCl-KCl melt system. The knowledge on the basic chemical properties of these lanthanide oxides and U(III) in molten salt media is essential for developing suitable processes. However, few studies have been reported until now on the interaction between U metal and lanthanide oxides in LiCl-KCl melt. So, we studied the interaction between U(III) and Ln(III) by using the UV-VIS spectra. UV-vis spectrometry is a strong analytical technique for characterizing chemical species and their behavior in molten salt

Study of tryptophan assisted synthesis of gold nanoparticles by combining UV-Vis, fluorescence, and SERS spectroscopy

International Nuclear Information System (INIS)

Iosin, Monica; Baldeck, Patrice; Astilean, Simion

2010-01-01

We developed a rapid and non-toxic method for the preparation of colloidal gold nanoparticles (GNPs) by using tryptophan (Trp) as reducing/stabilizing agent. We show that the temperature has a major influence on the kinetics of gold ion reduction and the crystal growth, higher temperatures favoring the synthesis of anisotropic nanoparticles (triangles and hexagons). The as-synthesized nanostructures were characterized by UV-Vis absorption spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), fluorescence, and surface-enhanced Raman scattering (SERS) spectroscopy. The UV-Vis measurements confirmed that temperature is a critical factor in the synthesis process, having a major effect on the shape of the synthesized GNPs. Moreover, fluorescence spectroscopy was able to monitor the quenching of the Trp fluorescence during the in situ synthesis of GNPs. Using Trp as molecular analyte to evaluate the SERS efficiency of as-prepared GNPs at different temperatures, we demonstrated that the Raman enhancement of the synthesized gold nanoplates is higher than that of the gold spherical nanoparticles.

Application of UV-Vis spectrophotometric and chemiluminescent methods for the evaluation of the antioxidant action of curcumin

Czech Academy of Sciences Publication Activity Database

Stanchev, Stancho; Pencheva, I.; Konstantinov, S.; Obreshkova, D.; Hadjimitova, V.

2012-01-01

Roč. 77, č. 8 (2012), s. 1063-1069 ISSN 0352-5139 Institutional research plan: CEZ:AV0Z40550506 Keywords : curcumin * antioxidant * UV-Vis spectrophotometry * DNA complexation * chemiluminescence Subject RIV: CC - Organic Chemistry Impact factor: 0.912, year: 2012

Spontaneous Isomerization of Peptide Cation Radicals Following Electron Transfer Dissociation Revealed by UV-Vis Photodissociation Action Spectroscopy.

Science.gov (United States)

Imaoka, Naruaki; Houferak, Camille; Murphy, Megan P; Nguyen, Huong T H; Dang, Andy; Tureček, František

2018-01-16

Peptide cation radicals of the z-type were produced by electron transfer dissociation (ETD) of peptide dications and studied by UV-Vis photodissociation (UVPD) action spectroscopy. Cation radicals containing the Asp (D), Asn (N), Glu (E), and Gln (Q) residues were found to spontaneously isomerize by hydrogen atom migrations upon ETD. Canonical N-terminal [z 4 + H] +● fragment ion-radicals of the R-C ● H-CONH- type, initially formed by N-C α bond cleavage, were found to be minor components of the stable ion fraction. Vibronically broadened UV-Vis absorption spectra were calculated by time-dependent density functional theory for several [ ● DAAR + H] + isomers and used to assign structures to the action spectra. The potential energy surface of [ ● DAAR + H] + isomers was mapped by ab initio and density functional theory calculations that revealed multiple isomerization pathways by hydrogen atom migrations. The transition-state energies for the isomerizations were found to be lower than the dissociation thresholds, accounting for the isomerization in non-dissociating ions. The facile isomerization in [ ● XAAR + H] + ions (X = D, N, E, and Q) was attributed to low-energy intermediates having the radical defect in the side chain that can promote hydrogen migration along backbone C α positions. A similar side-chain mediated mechanism is suggested for the facile intermolecular hydrogen migration between the c- and [z + H] ● -ETD fragments containing Asp, Asn, Glu, and Gln residues. Graphical Abstract ᅟ.

Spontaneous Isomerization of Peptide Cation Radicals Following Electron Transfer Dissociation Revealed by UV-Vis Photodissociation Action Spectroscopy

Science.gov (United States)

Imaoka, Naruaki; Houferak, Camille; Murphy, Megan P.; Nguyen, Huong T. H.; Dang, Andy; Tureček, František

2018-01-01

Peptide cation radicals of the z-type were produced by electron transfer dissociation (ETD) of peptide dications and studied by UV-Vis photodissociation (UVPD) action spectroscopy. Cation radicals containing the Asp (D), Asn (N), Glu (E), and Gln (Q) residues were found to spontaneously isomerize by hydrogen atom migrations upon ETD. Canonical N-terminal [z4 + H]+● fragment ion-radicals of the R-C●H-CONH- type, initially formed by N-Cα bond cleavage, were found to be minor components of the stable ion fraction. Vibronically broadened UV-Vis absorption spectra were calculated by time-dependent density functional theory for several [●DAAR + H]+ isomers and used to assign structures to the action spectra. The potential energy surface of [●DAAR + H]+ isomers was mapped by ab initio and density functional theory calculations that revealed multiple isomerization pathways by hydrogen atom migrations. The transition-state energies for the isomerizations were found to be lower than the dissociation thresholds, accounting for the isomerization in non-dissociating ions. The facile isomerization in [●XAAR + H]+ ions (X = D, N, E, and Q) was attributed to low-energy intermediates having the radical defect in the side chain that can promote hydrogen migration along backbone Cα positions. A similar side-chain mediated mechanism is suggested for the facile intermolecular hydrogen migration between the c- and [z + H]●-ETD fragments containing Asp, Asn, Glu, and Gln residues. [Figure not available: see fulltext.

Predicting Key Agronomic Soil Properties with UV-Vis Fluorescence Measurements Combined with Vis-NIR-SWIR Reflectance Spectroscopy: A Farm-Scale Study in a Mediterranean Viticultural Agroecosystem.

Science.gov (United States)

Vaudour, Emmanuelle; Cerovic, Zoran G; Ebengo, Dav M; Latouche, Gwendal

2018-04-10

For adequate crop and soil management, rapid and accurate techniques for monitoring soil properties are particularly important when a farmer starts up his activities and needs a diagnosis of his cultivated fields. This study aimed to evaluate the potential of fluorescence measured directly on 146 whole soil solid samples, for predicting key soil properties at the scale of a 6 ha Mediterranean wine estate with contrasting soils. UV-Vis fluorescence measurements were carried out in conjunction with reflectance measurements in the Vis-NIR-SWIR range. Combining PLSR predictions from Vis-NIR-SWIR reflectance spectra and from a set of fluorescence signals enabled us to improve the power of prediction of a number of key agronomic soil properties including SOC, N tot , CaCO₃, iron, fine particle-sizes (clay, fine silt, fine sand), CEC, pH and exchangeable Ca 2+ with cross-validation RPD ≥ 2 and R² ≥ 0.75, while exchangeable K⁺, Na⁺, Mg 2+ , coarse silt and coarse sand contents were fairly predicted (1.42 ≤ RPD < 2 and 0.54 ≤ R² < 0.75). Predictions of SOC, N tot , CaCO₃, iron contents, and pH were still good (RPD ≥ 1.8, R² ≥ 0.68) when using a single fluorescence signal or index such as SFR_R or FERARI, highlighting the unexpected importance of red excitations and indices derived from plant studies. The predictive ability of single fluorescence indices or original signals was very significant for topsoil: this is very important for a farmer who wishes to update information on soil nutrient for the purpose of fertility diagnosis and particularly nitrogen fertilization. These results open encouraging perspectives for using miniaturized fluorescence devices enabling red excitation coupled with red or far-red fluorescence emissions directly in the field.

Predicting Key Agronomic Soil Properties with UV-Vis Fluorescence Measurements Combined with Vis-NIR-SWIR Reflectance Spectroscopy: A Farm-Scale Study in a Mediterranean Viticultural Agroecosystem

Directory of Open Access Journals (Sweden)

Emmanuelle Vaudour

2018-04-01

Full Text Available For adequate crop and soil management, rapid and accurate techniques for monitoring soil properties are particularly important when a farmer starts up his activities and needs a diagnosis of his cultivated fields. This study aimed to evaluate the potential of fluorescence measured directly on 146 whole soil solid samples, for predicting key soil properties at the scale of a 6 ha Mediterranean wine estate with contrasting soils. UV-Vis fluorescence measurements were carried out in conjunction with reflectance measurements in the Vis-NIR-SWIR range. Combining PLSR predictions from Vis-NIR-SWIR reflectance spectra and from a set of fluorescence signals enabled us to improve the power of prediction of a number of key agronomic soil properties including SOC, Ntot, CaCO3, iron, fine particle-sizes (clay, fine silt, fine sand, CEC, pH and exchangeable Ca2+ with cross-validation RPD ≥ 2 and R² ≥ 0.75, while exchangeable K+, Na+, Mg2+, coarse silt and coarse sand contents were fairly predicted (1.42 ≤ RPD < 2 and 0.54 ≤ R² < 0.75. Predictions of SOC, Ntot, CaCO3, iron contents, and pH were still good (RPD ≥ 1.8, R² ≥ 0.68 when using a single fluorescence signal or index such as SFR_R or FERARI, highlighting the unexpected importance of red excitations and indices derived from plant studies. The predictive ability of single fluorescence indices or original signals was very significant for topsoil: this is very important for a farmer who wishes to update information on soil nutrient for the purpose of fertility diagnosis and particularly nitrogen fertilization. These results open encouraging perspectives for using miniaturized fluorescence devices enabling red excitation coupled with red or far-red fluorescence emissions directly in the field.

Robust and economical multi-sample, multi-wavelength UV/vis absorption and fluorescence detector for biological and chemical contamination

Science.gov (United States)

Lu, Peter J.; Hoehl, Melanie M.; Macarthur, James B.; Sims, Peter A.; Ma, Hongshen; Slocum, Alexander H.

2012-09-01

We present a portable multi-channel, multi-sample UV/vis absorption and fluorescence detection device, which has no moving parts, can operate wirelessly and on batteries, interfaces with smart mobile phones or tablets, and has the sensitivity of commercial instruments costing an order of magnitude more. We use UV absorption to measure the concentration of ethylene glycol in water solutions at all levels above those deemed unsafe by the United States Food and Drug Administration; in addition we use fluorescence to measure the concentration of d-glucose. Both wavelengths can be used concurrently to increase measurement robustness and increase detection sensitivity. Our small robust economical device can be deployed in the absence of laboratory infrastructure, and therefore may find applications immediately following natural disasters, and in more general deployment for much broader-based testing of food, agricultural and household products to prevent outbreaks of poisoning and disease.

A novel combined approach of diffuse reflectance UV-Vis-NIR spectroscopy and multivariate analysis for non-destructive examination of blue ballpoint pen inks in forensic application.

Science.gov (United States)

Kumar, Raj; Sharma, Vishal

2017-03-15

The present research is focused on the analysis of writing inks using destructive UV-Vis spectroscopy (dissolution of ink by the solvent) and non-destructive diffuse reflectance UV-Vis-NIR spectroscopy along with Chemometrics. Fifty seven samples of blue ballpoint pen inks were analyzed under optimum conditions to determine the differences in spectral features of inks among same and different manufacturers. Normalization was performed on the spectroscopic data before chemometric analysis. Principal Component Analysis (PCA) and K-mean cluster analysis were used on the data to ascertain whether the blue ballpoint pen inks could be differentiated by their UV-Vis/UV-Vis NIR spectra. The discriminating power is calculated by qualitative analysis by the visual comparison of the spectra (absorbance peaks), produced by the destructive and non-destructive methods. In the latter two methods, the pairwise comparison is made by incorporating the clustering method. It is found that chemometric method provides better discriminating power (98.72% and 99.46%, in destructive and non-destructive, respectively) in comparison to the qualitative analysis (69.67%). Copyright © 2016 Elsevier B.V. All rights reserved.

The molecular chaperone function of α-crystallin is impaired by UV photolysis

International Nuclear Information System (INIS)

Borkman, R.F.; McLaughlin, J.

1995-01-01

Buffer solutions of the lens protein γ-crystallin and the enzymes aldolase and liver alcohol dehydrogenase became turbid and formed solid precipitate upon exposure to an elevated temperature of 63 o C or to UV radiation at 308 nm. When α-crystallin was added to the protein solutions in stoichiometric amounts, heat or UV irradiation did not cause turbidity, or turbidity developed much less rapidly than in the absence of α-crystallin. Hence, normal α-crystallin functioned as a ''molecular chaperone,'' providing protection against both UV and heat-induced protein aggregation. When α-crystallin was preirradiated with UV at 308 nm, its ability to function as a chaperone vis-a-vis both UV and heat-induced aggregation was significantly impaired, but only at relatively high UV doss. (author)

Enhanced photocatalytic activity for H2 evolution under irradiation of UV-vis light by Au-modified nitrogen-doped TiO2.

Science.gov (United States)

Zhao, Weirong; Ai, Zhuyu; Dai, Jiusong; Zhang, Meng

2014-01-01

Photocatalytic water splitting for hydrogen evolution is a potential way to solve many energy and environmental issues. Developing visible-light-active photocatalysts to efficiently utilize sunlight and finding proper ways to improve photocatalytic activity for H2 evolution have always been hot topics for research. This study attempts to expand the use of sunlight and to enhance the photocatalytic activity of TiO2 by N doping and Au loading. Au/N-doped TiO2 photocatalysts were synthesized and successfully used for photocatalytic water splitting for H2 evolution under irradiation of UV and UV-vis light, respectively. The samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), and photoelectrochemical characterizations. DRS displayed an extension of light absorption into the visible region by doping of N and depositing with Au, respectively. PL analysis indicated electron-hole recombination due to N doping and an efficient inhibition of electron-hole recombination due to the loaded Au particles. Under the irradiation of UV light, the photocatalytic hydrogen production rate of the as-synthesized samples followed the order Au/TiO2 > Au/N-doped TiO2 > TiO2 > N-doped TiO2. While under irradiation of UV-vis light, the N-TiO2 and Au/N-TiO2 samples show higher H2 evolution than their corresponding nitrogen-free samples (TiO2 and Au/TiO2). This inconsistent result could be attributed to the doping of N and the surface plasmonic resonance (SPR) effect of Au particles extending the visible light absorption. The photoelectrochemical characterizations further indicated the enhancement of the visible light response of Au/N-doped TiO2. Comparative studies have shown that a combination of nitrogen doping and Au loading enhanced the visible light response of TiO2 and increased the utilization of solar energy, greatly

Enhanced photocatalytic activity for H2 evolution under irradiation of UV-vis light by Au-modified nitrogen-doped TiO2.

Directory of Open Access Journals (Sweden)

Weirong Zhao

Full Text Available BACKGROUND PURPOSE: Photocatalytic water splitting for hydrogen evolution is a potential way to solve many energy and environmental issues. Developing visible-light-active photocatalysts to efficiently utilize sunlight and finding proper ways to improve photocatalytic activity for H2 evolution have always been hot topics for research. This study attempts to expand the use of sunlight and to enhance the photocatalytic activity of TiO2 by N doping and Au loading. METHODS: Au/N-doped TiO2 photocatalysts were synthesized and successfully used for photocatalytic water splitting for H2 evolution under irradiation of UV and UV-vis light, respectively. The samples were characterized using X-ray diffraction (XRD, transmission electron microscopy (TEM, X-ray photoelectron spectroscopy (XPS, UV-vis diffuse reflectance spectroscopy (DRS, photoluminescence spectroscopy (PL, and photoelectrochemical characterizations. RESULTS: DRS displayed an extension of light absorption into the visible region by doping of N and depositing with Au, respectively. PL analysis indicated electron-hole recombination due to N doping and an efficient inhibition of electron-hole recombination due to the loaded Au particles. Under the irradiation of UV light, the photocatalytic hydrogen production rate of the as-synthesized samples followed the order Au/TiO2 > Au/N-doped TiO2 > TiO2 > N-doped TiO2. While under irradiation of UV-vis light, the N-TiO2 and Au/N-TiO2 samples show higher H2 evolution than their corresponding nitrogen-free samples (TiO2 and Au/TiO2. This inconsistent result could be attributed to the doping of N and the surface plasmonic resonance (SPR effect of Au particles extending the visible light absorption. The photoelectrochemical characterizations further indicated the enhancement of the visible light response of Au/N-doped TiO2. CONCLUSION: Comparative studies have shown that a combination of nitrogen doping and Au loading enhanced the visible light response of

TiO_2/WO_3 photoactive bilayers in the UV-Vis light region

International Nuclear Information System (INIS)

Vasilaki, E.; Vernardou, D.; Kenanakis, G.; Katsarakis, N.; Vamvakaki, M.

2017-01-01

In this work, photoactive bilayered films consisting of anatase TiO_2 and monoclinic WO_3 were synthesized by a sol-gel route. Titanium isopropoxide and tungsten hexachloride were used as metal precursors and deposition was achieved by spin-coating on Corning glass substrates. The samples were characterized by X-ray diffraction, photoluminescence, UV-Vis, and Raman spectroscopy, as well as field emission scanning electron microscopy. The prepared immobilized catalysts were tested for their photocatalytic performance by the decolorization of methylene blue in aqueous matrices, under UV-Vis light irradiation. The annealing process influenced the crystallinity of the bilayered films, while the concentration of the tungsten precursor solution and the position of the tungsten trioxide layer further affected their photocatalytic performance. In particular, the photocatalytic performance of the bilayered films was optimized at a concentration of 0.1 M of the WO_3 precursor solution, when deposited as an overlying layer on TiO_2 by two annealing steps (∝76% methylene blue decolorization in 300 min of irradiation versus ∝59% in the case of a bare TiO_2 film). In general, the coupled layer catalysts exhibited superior photoactivity compared to that of bare TiO_2 films with WO_3 acting as an electron trap, resulting, therefore, in a more efficient electron-hole separation and inhibiting their recombination. (orig.)

Solid-phase photocatalytic degradation of polystyrene plastic with goethite modified by boron under UV-vis light irradiation

International Nuclear Information System (INIS)

Liu Guanglong; Zhu Duanwei; Zhou Wenbing; Liao Shuijiao; Cui Jingzhen; Wu Kang; Hamilton, David

2010-01-01

A novel photodegradable polyethylene-boron-goethite (PE-B-goethite) composite film was prepared by embedding the boron-doped goethite into the commercial polyethylene. The goethite catalyst was modified by boron in order to improve its photocatalytic efficiency under the ultraviolet and visible light irradiation. Solid-phase photocatalytic degradation of the PE-B-goethite composite film was carried out in an ambient air at room temperature under ultraviolet and visible light irradiation. The properties of composite films were compared with those of the pure PE films and the PE-goethite composite films through performing weight loss monitoring, scanning electron microscope (SEM) analysis, FT-IR spectroscopy and X-ray photoelectron spectroscopy (XPS). The photo-induced degradation of PE-B-goethite composite films was higher than that of the pure PE films and the PE-goethite composite films under the UV-irradiation, while there has been little change under the visible light irradiation. The weight loss of the PE-B-goethite (0.4 wt.%) composite film reached 12.6% under the UV-irradiation for 300 h. The photocatalytic degradation mechanism of the composite films was briefly discussed.

UV patterned nanoporous solid-liquid core waveguides

DEFF Research Database (Denmark)

Gopalakrishnan, Nimi; Sagar, Kaushal Shashikant; Christiansen, Mads Brøkner

2010-01-01

Nanoporous Solid-Liquid core waveguides were prepared by UV induced surface modification of hydrophobic nanoporous polymers. With this method, the index contrast (delta n = 0.20) is a result of selective water infiltration. The waveguide core is defined by UV light, rendering the exposed part...

Standardized UV-vis spectra as the foundation for a threshold-based, integrated photosafety evaluation.

Science.gov (United States)

Bauer, Daniel; Averett, Lacey A; De Smedt, Ann; Kleinman, Mark H; Muster, Wolfgang; Pettersen, Betty A; Robles, Catherine

2014-02-01

Phototoxicity is a relatively common phenomenon and is an adverse effect of some systemic drugs. The fundamental initial step of photochemical reactivity is absorption of a photon; however, little guidance has been provided thus far regarding how ultraviolet-visible (UV-vis) light absorption spectra may be used to inform testing strategies for investigational drugs. Here we report the results of an inter-laboratory study comparing the data from harmonized UV-vis light absorption spectra obtained in methanol with data from the in vitro 3T3 Neutral Red Uptake Phototoxicity Test. Six pharmaceutical companies submitted data according to predefined quality criteria for 76 compounds covering a wide range of chemical classes showing a diverse but "positive"-enhanced distribution of photo irritation factors (22%: PIF5). For compounds being formally positive (PIF value above 5) the lowest reported molar extinction coefficient (MEC) was 1700 L mol⁻¹ cm⁻¹ in methanol. However, the majority of these formally positive compounds showed MEC values being significantly higher (up to almost 40,000 L mol⁻¹ cm⁻¹). In conclusion, an MEC value of 1000 L mol⁻¹ cm⁻¹ may represent a reasonable and pragmatic threshold warranting further experimental photosafety evaluation. Copyright © 2013 Elsevier Inc. All rights reserved.

Photocatalytic performance of Sn-doped and undoped TiO2 nanostructured thin films under UV and vis-lights

International Nuclear Information System (INIS)

Arpac, E.; Sayilkan, F.; Asiltuerk, M.; Tatar, P.; Kiraz, Nadir; Sayilkan, H.

2007-01-01

Sn-doped and undoped nano-TiO 2 particles have been synthesized by hydrotermal process without solvent at 200 deg. C in 1 h. Nanostructure-TiO 2 based thin films have been prepared on glass substrate by spin-coating technique. The structure, surface morphology and optical properties of the thin films and the particles have been investigated by element analysis and XRD, SEM, BET and UV-vis-NIR techniques. The photocatalytic performance of the films were tested for degradation of Malachite Green dye in solution under UV and vis-lights. The results showed that (a) hydrothermally synthesized nano-TiO 2 particles are fully anatase crystalline form and are easily dispersed in water, (b) the coated surfaces have nearly super-hydrophilic properties and (c) the doping of transition metal ion efficiently improved the photocatalytic performance of the TiO 2 thin film

Detection of olive oil adulteration by low-field NMR relaxometry and UV-Vis spectroscopy upon mixing olive oil with various edible oils

Directory of Open Access Journals (Sweden)

S. Ok

2017-03-01

Full Text Available Adulteration of olive oil using unhealthy substitutes is considered a threat for public health. Low-field (LF proton (1H nuclear magnetic resonance (NMR relaxometry and ultra-violet (UV visible spectroscopy are used to detect adulteration of olive oil. Three different olive oil with different oleoyl acyl contents were mixed with almond, castor, corn, and sesame oils with three volumetric ratios, respectively. In addition, Arbequina olive oil was mixed with canola, flax, grape seed, peanut, soybean, and sunflower seed oils with three volumetric ratios. Transverse magnetization relaxation time (T2 curves were fitted with bi-exponential decaying functions. T2 times of each mixture of olive oils and castor oils, and olive oils and corn oils changed systematically as a function of volumetric ratio. To detect the adulteration in the mixtures with almond and sesame oils, both LF 1H NMR relaxometry and UV-Vis spectroscopy were needed, where UV-Vis-spectroscopy detected the adulteration qualitatively. In the mixtures of Arbequina olive oil and flax, peanut, soybean, and sunflower seed oils, both T21 and T22 values became longer systematically as the content of the olive oil was decreased. The unique UV-Vis maximum absorbance of flax oil at 320.0 nm shows the adulteration of olive oil qualitatively.

Detection of olive oil adulteration by low-field NMR relaxometry and UV-Vis spectroscopy upon mixing olive oil with various edible oils

International Nuclear Information System (INIS)

Ok, S.

2017-01-01

Adulteration of olive oil using unhealthy substitutes is considered a threat for public health. Low-field (LF) proton (1H) nuclear magnetic resonance (NMR) relaxometry and ultra-violet (UV) visible spectroscopy are used to detect adulteration of olive oil. Three different olive oil with different oleoyl acyl contents were mixed with almond, castor, corn, and sesame oils with three volumetric ratios, respectively. In addition, Arbequina olive oil was mixed with canola, flax, grape seed, peanut, soybean, and sunflower seed oils with three volumetric ratios. Transverse magnetization relaxation time (T2) curves were fitted with bi-exponential decaying functions. T2 times of each mixture of olive oils and castor oils, and olive oils and corn oils changed systematically as a function of volumetric ratio. To detect the adulteration in the mixtures with almond and sesame oils, both LF 1H NMR relaxometry and UV-Vis spectroscopy were needed, where UV-Vis-spectroscopy detected the adulteration qualitatively. In the mixtures of Arbequina olive oil and flax, peanut, soybean, and sunflower seed oils, both T21 and T22 values became longer systematically as the content of the olive oil was decreased. The unique UV-Vis maximum absorbance of flax oil at 320.0 nm shows the adulteration of olive oil qualitatively. [es

Growth of block copolymer stabilized metal nanoparticles probed simultaneously by in situ XAS and UV-Vis spectroscopy.

Science.gov (United States)

Nayak, C; Bhattacharyya, D; Jha, S N; Sahoo, N K

2016-01-01

The growth of Au and Pt nanoparticles from their respective chloride precursors using block copolymer-based reducers has been studied by simultaneous in situ measurement of XAS and UV-Vis spectroscopy at the energy-dispersive EXAFS beamline (BL-08) at INDUS-2 SRS at RRCAT, Indore, India. While the XANES spectra of the precursor give real-time information on the reduction process, the EXAFS spectra reveal the structure of the clusters formed at the intermediate stages of growth. The growth kinetics of both types of nanoparticles are found to be almost similar and are found to follow three stages, though the first stage of nucleation takes place earlier in the case of Au than in the case of Pt nanoparticles due to the difference in the reduction potential of the respective precursors. The first two stages of the growth of Au and Pt nanoparticles as obtained by in situ XAS measurements could be corroborated by simultaneous in situ measurement of UV-Vis spectroscopy also.

Influence of uranyl dibutylphosphate on the UV/VIS spectrophotometric online monitoring of uranium in tributylphosphate/hydrocarbon solvent

International Nuclear Information System (INIS)

Creech, E.T.; Rutenberg, A.C.; Smithwick, R.W.; Seals, R.D.

1984-01-01

In the uranium recovery process at the Y-12 Plant uranium is recovered from aqueous uranyl solutions by extraction into a solvent consisting of 30% tributylphosphate (TBP) and 70% hydrocarbon solvent. Within this process the uranium is continuously monitored by a UV/VIS absorbance measurement of the uranyl/tributylphosphate complex in the organic phase. The uranium is then further extracted from the organic phase to a final water phase. Dibutylphosphate (DBP), which is a decomposition product of TBP, builds up in the organic solvent. A very strong complex of uranyl/dibutylphosphate is formed which cannot be extracted into the aqueous phase. Prior to this work the uranyl/dibutylphosphate complex absorbance was assumed to be the same as the uranyl tributylphosphate complex. To determine the effect of the presence of uranyl/dibutylphosphate on the continuous UV/VIS monitor required (a) the purification of commercial dibutylphosphate, (b) the synthesis, and (c) the characterization of uranyl/dibutylphosphate

Flame Characterization Using a Tunable Solid-State Laser with Direct UV Pumping

Science.gov (United States)

Kamal, Mohammed M.; Dubinskii, Mark A.; Misra, Prabhakar

1996-01-01

Tunable solid-state lasers with direct UV pumping, based on d-f transitions of rare earth ions incorporated in wide band-gap dielectric crystals, are reliable sources of laser radiation that are suitable for excitation of combustion-related free radicals. We have employed such a laser for analytical flame characterization utilizing Laser-Induced Fluorescence (LIF) techniques. LIF spectra of alkane-air flames (used for studying combustion processes under normal and microgravity conditions) excited in the region of the A-X (0,0) OH-absorption band have been recorded and found to be both temperature-sensitive and positionally-sensitive. In addition, also clearly noticeable was the sensitivity of the spectra to the specific wavelength used for data registration. The LiCAF:Ce laser shows good prospects for being able to cover the spectral region between 280 and 340 nm and therefore be used excitation of combustion-intermediates such as the hydroxyl OH, methoxy CH30 and methylthio CH3S radicals.

Styrene oligomerization as a molecular probe reaction for zeolite acidity: a UV-Vis spectroscopy and DFT study

NARCIS (Netherlands)

Buurmans, I.L.C.; Pidko, E.A.; Groot, de J.M.; Stavitski, E.; Santen, van R.A.; Weckhuysen, B.M.

2010-01-01

A series of H-ZSM-5 crystallites with different framework Si/Al ratios was studied by analyzing the kinetics and reaction mechanism of the oligomerization of 4-fluorostyrene as molecular probe reaction for Brønsted acidity. The formation of carbocationic species was followed by UV-Vis spectroscopy.

A rapid approach for measuring silver nanoparticle concentration and dissolution in seawater by UV-Vis.

Science.gov (United States)

Sikder, Mithun; Lead, Jamie R; Chandler, G Thomas; Baalousha, Mohammed

2018-03-15

Detection and quantification of engineered nanoparticles (NPs) in environmental systems is challenging and requires sophisticated analytical equipment. Furthermore, dissolution is an important environmental transformation process for silver nanoparticles (AgNPs) which affects the size, speciation and concentration of AgNPs in natural water systems. Herein, we present a simple approach for the detection, quantification and measurement of dissolution of PVP-coated AgNPs (PVP-AgNPs) based on monitoring their optical properties (extinction spectra) using UV-vis spectroscopy. The dependence of PVP-AgNPs extinction coefficient (ɛ) and maximum absorbance wavelength (λ max ) on NP size was experimentally determined. The concentration, size, and extinction spectra of PVP-AgNPs were characterized during dissolution in 30ppt synthetic seawater. AgNPs concentration was determined as the difference between the total and dissolved Ag concentrations measured by inductively coupled plasma-mass spectroscopy (ICP-MS); extinction spectra of PVP-AgNPs were monitored by UV-vis; and size evolution was monitored by atomic force microscopy (AFM) over a period of 96h. Empirical equations for the dependence of maximum absorbance wavelength (λ max ) and extinction coefficient (ɛ) on NP size were derived. These empirical formulas were then used to calculate the size and concentration of PVP-AgNPs, and dissolved Ag concentration released from PVP-AgNPs in synthetic seawater at variable particle concentrations (i.e. 25-1500μgL -1 ) and in natural seawater at particle concentration of 100μgL -1 . These results suggest that UV-vis can be used as an easy and quick approach for detection and quantification (size and concentration) of sterically stabilized PVP-AgNPs from their extinction spectra. This approach can also be used to monitor the release of Ag from PVP-AgNPs and the concurrent NP size change. Finally, in seawater, AgNPs dissolve faster and to a higher extent with the decrease in NP

Interaction between morin and AOT reversed micelles--studies with UV-vis at 25 °C.

Science.gov (United States)

Bhattarai, Ajaya; Wilczura-Wachnik, H

2014-01-30

The precise measurements of morin absorbance in presence of surfactant/solvent/water systems at 25 °C by UV-vis technique are reported. The surfactant used in presented study was sodium bis(2-ethylhexyl) sulfosuccinate called Aerosol-OT or AOT. The solvents selected were: ethanol, ethylene glycol, and n-decanol. The concentrations of AOT were varied between 0.001 and 0.4 mol/kg. Morin concentration in quvette during UV-vis registration was not equals in all solvent because of its different solubility and absorption intensity depending on the solvent. Water concentration in the studied systems was defined by R parameter according to relation: R=[H2O]/[AOT] and was equal 0, 30 and 40 in ethanol; 0, 10, 20 and 30 in ethylene glycol and 0, 10, 20, 30, and 40 in n-decanol. In presented work a Nernstian distribution of morin between the organic and micellar phases was assumed. The intensity of morin absorbance as a function of AOT concentration was analyzed. Using Non-linear Regression Procedure (NLREG) morin binding constant (K' [mol/kg]), and morin distribution constant (K) between organic phase and AOT micellar phase have been calculated. The experimental results have shown a significant influence of solvent, surfactant and water presence on morin UV-vis spectrum. Calculated data pointed out on different transfer of morin molecules from the organic to micellar phase depending on the solvent. Moreover, results of calculations indicate on competition between morin and water molecules interacting with AOT polar heads. Morin molecules privileged location in AOT reversed micelles strongly depends on the solvent. In case of systems with ethylene glycol as solvent is possible morin molecules location in polar cores of AOT reversed micelles as results of strong interaction between AOT polar heads and morin hydroxyl groups, whereas in case of ethanol and n-decanol morin molecules are located in palisade layer. Copyright © 2013 Elsevier B.V. All rights reserved.

Effect of fungal mycelia on the HPLC-UV and UV-vis spectrophotometric assessment of mycelium-bound epoxide hydrolase using glycidyl phenyl ether.

Science.gov (United States)

Dolcet, Marta M; Torres, Mercè; Canela, Ramon

2016-06-25

The use of mycelia as biocatalysts has technical and economic advantages. However, there are several difficulties in obtaining accurate results in mycelium-catalysed reactions. Firstly, sample extraction, indispensable because of the presence of mycelia, can bring into the extract components with a similar structure to that of the analyte of interest; secondly, mycelia can influence the recovery of the analyte. We prepared calibration standards of 3-phenoxy-1,2-propanediol (PPD) in the pure solvent and in the presence of mycelia (spiked before or after extraction) from five fungi (Aspergillus niger, Aspergillus tubingensis, Penicillium aurantiogriseum, Penicillium sp. and Aspergillus terreus). The quantification of PPD was carried out by HPLC-UV and UV-vis spectrophotometry. The manuscript shows that the last method is as accurate as the HPLC method. However, the colorimetric method led to a higher data throughput, which allowed the study of more samples in a shorter time. Matrix effects were evaluated visually from the plotted calibration data and statistically by simultaneously comparing the intercept and slope of calibration curves performed with solvent, post-extraction spiked standards and pre-extraction spiked standards. Significant differences were found between the post- and pre-extraction spiked matrix-matched functions. Pre-extraction spiked matrix-matched functions based on A. tubingensis mycelia, selected as the reference, were validated and used to compensate for low recoveries. These validated functions were successfully applied to the quantification of PPD achieved during the hydrolysis of glycidyl phenyl ether by mycelium-bound epoxide hydrolases and equivalent hydrolysis yields were determined by HPLC-UV and UV-vis spectrophotometry. This study may serve as starting point to implement matrix effects evaluation when mycelium-bound epoxide hydrolases are studied. Copyright © 2016 Elsevier B.V. All rights reserved.

The translucency of dental composites investigated by UV-VIS spectroscopy

International Nuclear Information System (INIS)

Dumitrescu, L. Silaghi; Pastrav, O.; Prejmerean, C.; Prodan, D.; Boboia, S.; Codruta, S.; Moldovan, M.

2013-01-01

Translucency is the property of a material to partially transmit and diffuse incident light, and can be described as a partial opacity or a state between complete opacity and complete transparency. The purpose of this study is to evaluate the translucency index of resin composites according to their chemical structure and to the light source used for curing. Our study was achieved on four commercial composite samples (30 mm × 2 mm) cured with two different lamps (Optilux - halogen bulb and Ultralight - LED). Measurements were made with a UV-VIS spectrophotometer, and the reflection spectrum was recorded in the 380-770 nm region on white and black, compared with a SPECTRALON standard white. For all materials cured with the LED lamp on the glossy sides, the best results were given by Tetric Evo Ceram followed by Filtek Supreme, Restacril RO and Premise. The measurements made on samples cured with an Optilux lamp, to the smooth and rough sides of the samples, revealed that the highest index of translucency is provided by Tetric Evo Ceram on the smooth side, followed by Filtek Supreme, Restacril RO and Premises. We can say that the translucency of the composites is mostly determined by the chemical composition of the material, which is observed from transmittance values recorded for each sample, and by the source of radiation applied on the sample

The translucency of dental composites investigated by UV-VIS spectroscopy

Science.gov (United States)

Dumitrescu, L. Silaghi; Pastrav, O.; Prejmerean, C.; Prodan, D.; Boboia, S.; Codruta, S.; Moldovan, M.

2013-11-01

Translucency is the property of a material to partially transmit and diffuse incident light, and can be described as a partial opacity or a state between complete opacity and complete transparency. The purpose of this study is to evaluate the translucency index of resin composites according to their chemical structure and to the light source used for curing. Our study was achieved on four commercial composite samples (30 mm × 2 mm) cured with two different lamps (Optilux - halogen bulb and Ultralight - LED). Measurements were made with a UV-VIS spectrophotometer, and the reflection spectrum was recorded in the 380-770 nm region on white and black, compared with a SPECTRALON standard white. For all materials cured with the LED lamp on the glossy sides, the best results were given by Tetric Evo Ceram followed by Filtek Supreme, RestacrilRO and Premise. The measurements made on samples cured with an Optilux lamp, to the smooth and rough sides of the samples, revealed that the highest index of translucency is provided by Tetric Evo Ceram on the smooth side, followed by Filtek Supreme, RestacrilRO and Premises. We can say that the translucency of the composites is mostly determined by the chemical composition of the material, which is observed from transmittance values recorded for each sample, and by the source of radiation applied on the sample.

An Enhanced UV-Vis-NIR an d Flexible Photodetector Based on Electrospun ZnO Nanowire Array/PbS Quantum Dots Film Heterostructure.

Science.gov (United States)

Zheng, Zhi; Gan, Lin; Zhang, Jianbing; Zhuge, Fuwei; Zhai, Tianyou

2017-03-01

ZnO nanostructure-based photodetectors have a wide applications in many aspects, however, the response range of which are mainly restricted in the UV region dictated by its bandgap. Herein, UV-vis-NIR sensitive ZnO photodetectors consisting of ZnO nanowires (NW) array/PbS quantum dots (QDs) heterostructures are fabricated through modified electrospining method and an exchanging process. Besides wider response region compared to pure ZnO NWs based photodetectors, the heterostructures based photodetectors have faster response and recovery speed in UV range. Moreover, such photodetectors demonstrate good flexibility as well, which maintain almost constant performances under extreme (up to 180°) and repeat (up to 200 cycles) bending conditions in UV-vis-NIR range. Finally, this strategy is further verified on other kinds of 1D nanowires and 0D QDs, and similar enhancement on the performance of corresponding photodetecetors can be acquired, evidencing the universality of this strategy.

Ultrafast Infrared and UV-vis Studies of the Photochemistry of Methoxycarbonylphenyl Azides in Solution

OpenAIRE

Xue, Jiadan; Luk, Hoi Ling; Eswaran, S. V.; Hadad, Christopher M.; Platz, Matthew S.

2012-01-01

The photochemistry of 4-methoxycarbonylphenyl azide (2a), 2-methoxycarbonylphenyl azide (3a) and 2-methoxy-6-methoxycarbonylphenyl azide (4a) were studied by ultrafast time-resolved infrared (IR) and UV-vis spectroscopies in solution. Singlet nitrenes and ketenimines were observed and characterized for all three azides. Isoxazole species 3g and 4g are generated after photolysis of 3a and 4a, respectively, in acetonitrile. Triplet nitrene 4e formation correlated with the decay of singlet nitre...

In situ, rapid, and temporally resolved measurements of cellulase adsorption onto lignocellulosic substrates by UV-vis spectrophotometry

Science.gov (United States)

Hao Liu; J. Y. Zhu; X. S. Chai

2011-01-01

This study demonstrated two in situ UV-vis spectrophotometric methods for rapid and temporally resolved measurements of cellulase adsorption onto cellulosic and lignocellulosic substrates during enzymatic hydrolysis. The cellulase protein absorption peak at 280 nm was used for quantification. The spectral interferences from light scattering by small fibers (fines) and...

Computing UV/vis spectra using a combined molecular dynamics and quantum chemistry approach: bis-triazin-pyridine (BTP) ligands studied in solution.

Science.gov (United States)

Höfener, Sebastian; Trumm, Michael; Koke, Carsten; Heuser, Johannes; Ekström, Ulf; Skerencak-Frech, Andrej; Schimmelpfennig, Bernd; Panak, Petra J

2016-03-21

We report a combined computational and experimental study to investigate the UV/vis spectra of 2,6-bis(5,6-dialkyl-1,2,4-triazin-3-yl)pyridine (BTP) ligands in solution. In order to study molecules in solution using theoretical methods, force-field parameters for the ligand-water interaction are adjusted to ab initio quantum chemical calculations. Based on these parameters, molecular dynamics (MD) simulations are carried out from which snapshots are extracted as input to quantum chemical excitation-energy calculations to obtain UV/vis spectra of BTP ligands in solution using time-dependent density functional theory (TDDFT) employing the Tamm-Dancoff approximation (TDA). The range-separated CAM-B3LYP functional is used to avoid large errors for charge-transfer states occurring in the electronic spectra. In order to study environment effects with theoretical methods, the frozen-density embedding scheme is applied. This computational procedure allows to obtain electronic spectra calculated at the (range-separated) DFT level of theory in solution, revealing solvatochromic shifts upon solvation of up to about 0.6 eV. Comparison to experimental data shows a significantly improved agreement compared to vacuum calculations and enables the analysis of relevant excitations for the line shape in solution.

Multiconfigurational and DFT analyses of the electromeric formulation and UV-vis absorption spectra of the superoxide adduct of ferrous superoxide reductase.

Science.gov (United States)

Attia, Amr A A; Cioloboc, Daniela; Lupan, Alexandru; Silaghi-Dumitrescu, Radu

2016-12-01

The putative initial adduct of ferrous superoxide reductase (SOR) with superoxide has been alternatively formulated as ferric-peroxo or ferrous-superoxo. The ~600-nm UV-vis absorption band proposed to be assigned to this adduct (either as sole intermediate in the SOR catalytic cycle, or as one of the two intermediates) has recently been interpreted as due to a ligand-to-metal charge transfer, involving thiolate and superoxide in a ferrous complex, contrary to an alternative assignment as a predominantly cysteine thiolate-to-ferric charge transfer in a ferric-peroxo electromer. In an attempt to clarify the electromeric formulation of this adduct, we report a computational study using a multiconfigurational complete active space self-consistent field (MC-CASSCF) wave function approach as well as modelling the UV-vis absorption spectra with time-dependent density functional theory (TD-DFT). The MC-CASSCF calculations disclose a weak interaction between iron and the dioxygenic ligand and a dominant configuration with an essentially ferrous-superoxo character. The computed UV-vis absorption spectra reveal a marked dependence on the choice of density functional - both in terms of location of bands and in terms of orbital contributors. For the main band in the visible region, besides the recently reported thiolate-to-superoxide charge transfer, a more salient, and less functional-dependent, feature is a thiolate-to-ferric iron charge transfer, consistent with a ferric-peroxo electromer. By contrast, the computed UV-vis spectra of a ferric-hydroperoxo SOR model match distinctly better (and with no qualitative dependence on the DFT methodology) the 600-nm band as due to a mainly thiolate-to-ferric character - supporting the assignment of the SOR "600-nm intermediate" as a S=5/2 ferric-hydroperoxo species. Copyright © 2016 Elsevier Inc. All rights reserved.

Measurement of soluble solids content in watermelon by Vis/NIR diffuse transmittance technique*

OpenAIRE

Tian, Hai-qing; Ying, Yi-bin; Lu, Hui-shan; Fu, Xia-ping; Yu, Hai-yan

2007-01-01

Watermelon is a popular fruit in the world with soluble solids content (SSC) being one of the major characteristics used for assessing its quality. This study was aimed at obtaining a method for nondestructive SSC detection of watermelons by means of visible/near infrared (Vis/NIR) diffuse transmittance technique. Vis/NIR transmittance spectra of intact watermelons were acquired using a low-cost commercially available spectrometer operating over the range 350~1000 nm. Spectra data were analyz...

The structural defects and UV-VIS spectral characterization of TiO2 particles doped in the lattice with Cr3+ cations

International Nuclear Information System (INIS)

Liu, Z.L.; Cui, Z.L.; Zhang, Z.K.

2005-01-01

Titania nanoparticles doped with Cr 3+ (2% relative to molar quantity of titania) were prepared and examined by EDS, HRTEM, XRD, and UV-VIS analysis. HRTEM images showed the detailed atomic arrays and vacancy defects of the doped Titania nanocrystals and revealed that the implanted Cr element existed in titania mainly as Cr 3+ ions which located at the lattice positions of Ti 4+ ions. Compared with pure titania, the UV-VIS spectra of the Cr 3+ doped titania show significantly increased absorbance in visible light region. This indicated that the presence of the Cr 3+ ions affected the lattice structure of titania nanocrystals and plays an reformative role in spectral feature of titania

Molecular dynamics simulation and TDDFT study of the structures and UV-vis absorption spectra of MCT-β-CD and its inclusion complexes.

Science.gov (United States)

Lu, Huijuan; Wang, Yujiao; Xie, Xiaomei; Chen, Feifei; Li, Wei

2015-01-01

In this research, the inclusion ratios and inclusion constants of MCT-β-CD/PERM and MCT-β-CD/CYPERM inclusion complexes were measured by UV-vis and fluorescence spectroscopy. The inclusion ratios are both 1:1, and the inclusion constants are 60 and 342.5 for MCT-β-CD/PERM and MCT-β-CD/CYPERM, respectively. The stabilities of inclusion complexes were investigated by MD simulation. MD shows that VDW energy plays a vital role in the stability of inclusion complex, and the destruction of inclusion complex is due to the increasing temperature. The UV-vis absorption spectra of MCT-β-CD and its inclusion complexes were studied by time-dependent density functional theory (TDDFT) method employing BLYP-D3, B3LYP-D3 and M06-2X-D3 functionals. BLYP-D3 well reproduces the UV-vis absorption spectrum and reveals that the absorption bands of MCT-β-CD mainly arise from n→π(∗) and n→σ(∗) transition, and those of inclusion complexes mainly arise from intramolecular charge transfer (ICT). ICT results in the shift of main absorption bands of MCT-β-CD. Copyright © 2015 Elsevier B.V. All rights reserved.

UV-Vis spectroscopy of tyrosine side-groups in studies of protein structure. Part 1: basic principles and properties of tyrosine chromophore.

Science.gov (United States)

Antosiewicz, Jan M; Shugar, David

2016-06-01

Spectroscopic properties of tyrosine residues may be employed in structural studies of proteins. Here we discuss several different types of UV-Vis spectroscopy, like normal, difference and second-derivative UV absorption spectroscopy, fluorescence spectroscopy, linear and circular dichroism spectroscopy, and Raman spectroscopy, and corresponding optical properties of the tyrosine chromophore, phenol, which are used to study protein structure.

ALTIUS: a spaceborne AOTF-based UV-VIS-NIR hyperspectral imager for atmospheric remote sensing

Science.gov (United States)

Dekemper, Emmanuel; Fussen, Didier; Van Opstal, Bert; Vanhamel, Jurgen; Pieroux, Didier; Vanhellemont, Filip; Mateshvili, Nina; Franssens, Ghislain; Voloshinov, Vitaly; Janssen, Christof; Elandaloussi, Hadj

2014-10-01

offers better risk mitigation in case of failure in one channel. In each channel, the spectral filter will be an acousto-optical tunable filter (AOTF). Such devices offer reasonable étendue with good spectral resolution and excellent robustness and compactness. TeO2-based AOTF's have already been used in space missions towards Mars and Venus (MEX and VEX, ESA). While such TeO2 crystals are common in VIS-NIR applications, they are not transparent below 350 nm. Recent progress towards UV AOTF's have been made with the advent of KDP-based filters. Through collaboration with the Moscow State University (MSU), several experiments were conducted on a KDP AOTF and gave confidence on this material. Here, we present the general concept of ALTIUS and its optical design with particular attention on the AOTF. Several results obtained with optical breadboards for the UV and VIS ranges will be exposed, such as the O3 and NO2 absorption cross-section measurements, or spectral images. These results illustrate the spectral and optical performances to be expected from an AOTF-based hyperspectral imager. Their implications for ALTIUS will be discussed

Combined operando Raman/UV-Vis-NIR spectroscopy as a tool to study supported metal oxide catalysts at work

NARCIS (Netherlands)

Tinnemans, Stanislaus Josephus

2006-01-01

A novel set-up has been developed in which two complementary spectroscopic techniques, namely operando Raman and UV-Vis-NIR spectroscopy, are combined. With this set-up it is possible to characterize catalytic materials under reaction conditions (high temperature, normal pressure) and in this way on

Interaction betwen Lead and Bone Protein to Affect Bone Calcium Level Using UV-Vis Spectroscopy

Science.gov (United States)

Noor, Z.; Azharuddin, A.; Aflanie, I.; Kania, N.; Suhartono, E.

2018-05-01

This present study aim to evaluate the interactions between lead (Pb) and with bone protein by UV-Vis approach. In addition, this prsent study also aim to investigate the effect of Pb on bone calcium (Ca) level. The present study was a true experimental study design to examine the impact of Pb exposure in bone of male rats (Rattus novergicus). The study involved 5 groups, P1 was the control group, while the other (P2-P5) were the case group with exposure of Pb in different concentration within 4 weeks. At the end of the exposure, the interaction between Pb and protein was determined using UV-Vis spectrophotometric method, and the Ca level was determined using permanganometric method. The results shows that that there is an interaction between Pb and bone protein. The result also shows that the value of the binding constant of Protein-Pb is 32.71. It means Pb have an high affinity to bind with bone protein, which promote a further reaction to induced the release of bone Ca from the bone protein. In conclusion, this present study found an obvious relationship between Pb and bone protein which promote a further reaction to increase the releasing of bone calcium.

Shedding Light on the Oxygen Reduction Reaction Mechanism in Ether-Based Electrolyte Solutions: A Study Using Operando UV-Vis Spectroscopy.

Science.gov (United States)

Hirshberg, Daniel; Sharon, Daniel; Afri, Michal; Lavi, Ronit; Frimer, Aryeh A; Metoki, Noa; Eliaz, Noam; Kwak, Won-Jin; Sun, Yang-Kook; Aurbach, Doron

2018-04-04

Using UV-vis spectroscopy in conjunction with various electrochemical techniques, we have developed a new effective operando methodology for investigating the oxygen reduction reactions (ORRs) and their mechanisms in nonaqueous solutions. We can follow the in situ formation and presence of superoxide moieties during ORR as a function of solvent, cations, anions, and additives in the solution. Thus, using operando UV-vis spectroscopy, we found evidence for the formation of superoxide radical anions during oxygen reduction in LiTFSI/diglyme electrolyte solutions. Nitro blue tetrazolium (NBT) was used to indicate the presence of superoxide moieties based on its unique spectral response. Indeed, the spectral response of NBT containing solutions undergoing ORR could provide a direct indication for the level of association of the Li cations with the electrolyte anions.

Luminescence of Er3+ doped double lead halide crystals under X-ray, UV, VIS and IR excitation

Science.gov (United States)

Serazetdinov, A. R.; Smirnov, A. A.; Pustovarov, V. A.; Isaenko, L. I.

2017-09-01

Er3+ doped double lead halide crystals incorporate a number of properties making them interesting for practical use in light conducting materials. X-ray excited luminescence (XRL) spectra, photoluminescence (PL) spectra in region of 1.5-3.5 eV, photoluminescence excitation (PLE) spectra (2.75-5 eV) and anti-stokes luminescence (ASL) spectra were measured at room temperature in KPb2Cl5 (KPC) and RbPb2Br5 (RPB) matrices doped with Er3+ (1%) ions and in KPC doped with Er3++ Yb3+ ions(1:3 ratio concentration). Intraconfigurational f→f transitions are observed in Er3+ ions in most of the cases. The concrete spectrum form is strongly dependent on the excitation energy. Under 980 nm excitation upper Er3+ levels are excited, showing upconversional processes. In case of 313 nm (UV) and 365 nm (VIS) excitation self trapped exciton luminescence was detected in RPB crystal. Additional Yb3+ doping ions strongly increase quantum yield under 980 nm excitation and this doping cause insignificant influence on quantum yield under VIS or UV excitation.

Simultaneous FTIR/UV-Vis study of reactions over metallo-zeolites. Approach to quantitative in situ studies

Czech Academy of Sciences Publication Activity Database

Sobalík, Zdeněk; Jíša, Kamil; Jirglová, Hana; Bernauer, B.

2007-01-01

Roč. 126, 1-2 (2007), s. 73-80 ISSN 0920-5861 R&D Projects: GA AV ČR 1ET400400413; GA ČR GA104/06/1254; GA ČR GA203/05/2309 Institutional research plan: CEZ:AV0Z40400503 Keywords : metallo-zeolites * FTIR/UV-Vis * adsorption * modeling * in-situ Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.764, year: 2007

Study of upscaling possibilities for antimony sulfide solid state sensitized solar cells

Science.gov (United States)

Nikolakopoulou, Archontoula; Raptis, Dimitrios; Dracopoulos, Vasilios; Sygellou, Lamprini; Andrikopoulos, Konstantinos S.; Lianos, Panagiotis

2015-03-01

Solid state solar cells of inverted structure were constructed by successive deposition of nanoparticulate titania, antimony sulfide sensitizer and P3HT on FTO electrodes with PEDOT:PSS:Ag as counter electrode. Sensitized photoanode electrodes were characterized by XRD, Raman, XPS, FESEM and UV-vis. Small laboratory scale cells were first constructed and optimized. Functional cells were obtained by annealing the antimony sulfide film either in air or in inert atmosphere. High short-circuit currents were recorded in both cases with air-annealed sample producing more current but lower voltage. Small unit cells were combined to form cell modules. Connection of unit cells in parallel increased current but not proportionally to that of the unit cell. Connection in series preserved current and generated voltage multiplication. Cells were constructed and studied under ambient conditions, without encapsulation. The results encourage upscaling of antimony sulfide solar cells.

Evaluation of the release characteristics of covalently attached or electrostatically bound biocidal polymers utilizing SERS and UV-Vis absorption

Directory of Open Access Journals (Sweden)

G. N. Mathioudakis

2016-09-01

Full Text Available In this work, biocidal polymers with antimicrobial quaternized ammonium groups introduced in the polymer biocidal chains either through covalent attachment or electrostatic interaction have been separately incorporated in a poly (methyl methacrylate polymer matrix. The objective of present study was to highlight the release characteristics of biocidal polymers, primarily in saline but also in water ethanol solutions, utilizing UV-Vis absorption and Surface Enhanced Raman Scattering (SERS. It is shown that through the combination of UV-Vis and SERS techniques, upon the release process, it is possible the discrimination of the polymeric backbone and the electrostatically bound biocidal species. Moreover, it is found that electrostatically bound and covalently attached biocidal species show different SERS patterns. The long term aim is the development of antimicrobial polymeric materials containing both ionically bound and covalently attached quaternary ammonium thus achieving a dual functionality in a single component polymeric design.

Use of UV-vis-NIR spectroscopy to monitor label-free interaction between molecular recognition elements and erythropoietin on a gold-coated polycarbonate platform.

Science.gov (United States)

Citartan, Marimuthu; Gopinath, Subash C B; Tominaga, Junji; Chen, Yeng; Tang, Thean-Hock

2014-08-01

Label-free-based detection is pivotal for real-time monitoring of biomolecular interactions and to eliminate the need for labeling with tags that can occupy important binding sites of biomolecules. One simplest form of label-free-based detection is ultraviolet-visible-near-infrared (UV-vis-NIR) spectroscopy, which measure changes in reflectivity as a means to monitor immobilization and interaction of biomolecules with their corresponding partners. In biosensor development, the platform used for the biomolecular interaction should be suitable for different molecular recognition elements. In this study, gold (Au)-coated polycarbonate was used as a platform and as a proof-of-concept, erythropoietin (EPO), a doping substance widely abused by the athletes was used as the target. The interaction of EPO with its corresponding molecular recognition elements (anti-EPO monoclonal antibody and anti-EPO DNA aptamer) is monitored by UV-vis-NIR spectroscopy. Prior to this, to show that UV-vis-NIR spectroscopy is a suitable method for measuring biomolecular interaction, the interaction between biotin and streptavidin was demonstrated via this strategy and reflectivity of this interaction decreased by 25%. Subsequent to this, interaction of the EPO with anti-EPO monoclonal antibody and anti-EPO DNA aptamer resulted in the decrease of reflectivity by 5% and 10%, respectively. The results indicated that Au-coated polycarbonate could be an ideal biosensor platform for monitoring biomolecular interactions using UV-vis-NIR spectroscopy. A smaller version of the Au-coated polycarbonate substrates can be derived from the recent set-up, to be applied towards detecting EPO abuse among atheletes. Copyright © 2014 Elsevier B.V. All rights reserved.

Self-assembly of nitrogen-doped carbon nanoparticles: a new ratiometric UV-vis optical sensor for the highly sensitive and selective detection of Hg(2+) in aqueous solution.

Science.gov (United States)

Ruan, Yudi; Wu, Lie; Jiang, Xiue

2016-05-23

Water-soluble nitrogen-doped carbon nanoparticles (N-CNPs) prepared by the one-step hydrothermal treatment of uric acid were found to show ratiometric changes in their UV-vis spectra due to Hg(2+)-mediated self-assembly. For the first time, such a property was developed into a UV-vis optical sensor for detecting Hg(2+) in aqueous solutions with high sensitively and selectively (detection limit = 1.4 nM). More importantly, this novel sensor exhibits a higher linear sensitivity over a wider concentration range compared with the fluorescence sensor based on the same N-CNPs. This work opens an exciting new avenue to explore the use of carbon nanoparticles in constructing UV-vis optical sensors for the detection of metal ions and the use of carbon nanoparticles as a new building block to self-assemble into superlattices.

A new on-axis micro-spectrophotometer for combining Raman, fluorescence and UV/Vis absorption spectroscopy with macromolecular crystallography at the Swiss Light Source

International Nuclear Information System (INIS)

Pompidor, Guillaume; Dworkowski, Florian S. N.; Thominet, Vincent; Schulze-Briese, Clemens; Fuchs, Martin R.

2013-01-01

The new version MS2 of the in situ on-axis micro-spectrophotometer at the macromolecular crystallography beamline X10SA of the Swiss Light Source supports the concurrent acquisition of Raman, resonance Raman, fluorescence and UV/Vis absorption spectra along with diffraction data. The combination of X-ray diffraction experiments with optical methods such as Raman, UV/Vis absorption and fluorescence spectroscopy greatly enhances and complements the specificity of the obtained information. The upgraded version of the in situ on-axis micro-spectrophotometer, MS2, at the macromolecular crystallography beamline X10SA of the Swiss Light Source is presented. The instrument newly supports Raman and resonance Raman spectroscopy, in addition to the previously available UV/Vis absorption and fluorescence modes. With the recent upgrades of the spectral bandwidth, instrument stability, detection efficiency and control software, the application range of the instrument and its ease of operation were greatly improved. Its on-axis geometry with collinear X-ray and optical axes to ensure optimal control of the overlap of sample volumes probed by each technique is still unique amongst comparable facilities worldwide and the instrument has now been in general user operation for over two years

Interference-Blind Microfluidic Sensor for Ascorbic Acid Determination by UV/vis Spectroscopy

DEFF Research Database (Denmark)

Bi, Hongyan; Oliveira Fernandes, Ana Carolina; Cardoso, Susana

2016-01-01

A microfluidic sensor is developed and targeted at specific ingredients determination in drug/food/beverage matrices. The surface of a serpentine polydimethylsiloxane (PDMS) microchannel is modified by enzyme via physisorption. When solutions containing target ingredients pass through...... the microfluidic channel, enzyme-catalyzed reaction occurs and only converts the target molecules to its products. The whole process is monitored by an end-channel UV/vis spectroscopic detection. Ascorbate oxidase and L-ascorbic acid (AA) are taken as enzyme-substrate model in this study to investigate......, specific, and accurate, and can be potentially used for fast quantification of ingredient in samples with complex matrix background. It is promising to be widely spread in food industry and quality control department...

UV-Vis spectrophotometry of quinone flow battery electrolyte for in situ monitoring and improved electrochemical modeling of potential and quinhydrone formation.

Science.gov (United States)

Tong, Liuchuan; Chen, Qing; Wong, Andrew A; Gómez-Bombarelli, Rafael; Aspuru-Guzik, Alán; Gordon, Roy G; Aziz, Michael J

2017-12-06

Quinone-based aqueous flow batteries provide a potential opportunity for large-scale, low-cost energy storage due to their composition from earth abundant elements, high aqueous solubility, reversible redox kinetics and their chemical tunability such as reduction potential. In an operating flow battery utilizing 9,10-anthraquinone-2,7-disulfonic acid, the aggregation of an oxidized quinone and a reduced hydroquinone to form a quinhydrone dimer causes significant variations from ideal solution behavior and of optical absorption from the Beer-Lambert law. We utilize in situ UV-Vis spectrophotometry to establish (a), quinone, hydroquinone and quinhydrone molar attenuation profiles and (b), an equilibrium constant for formation of the quinhydrone dimer (K QHQ ) ∼ 80 M -1 . We use the molar optical attenuation profiles to identify the total molecular concentration and state of charge at arbitrary mixtures of quinone and hydroquinone. We report density functional theory calculations to support the quinhydrone UV-Vis measurements and to provide insight into the dimerization conformations. We instrument a quinone-bromine flow battery with a Pd-H reference electrode in order to demonstrate how complexation in both the negative (quinone) and positive (bromine) electrolytes directly impacts measured half-cell and full-cell voltages. This work shows how accounting for electrolyte complexation improves the accuracy of electrochemical modeling of flow battery electrolytes.

A novel orange-red emitting NaCaVO{sub 4}:Sm{sup 3+} phosphor for solid state lighting

Energy Technology Data Exchange (ETDEWEB)

Biswas, Pankaj, E-mail: pankaj79biswas@gmail.com; Kumar, Vinay, E-mail: vinaykdhiman@yahoo.com [School of Physics, Shri Mata Vaishno Devi University, Katra-182320 J& K (India); Ntwaeaborwa, O. M.; Swart, H. C. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein, ZA9300 (South Africa)

2016-05-06

The samarium doped NaCaVO{sub 4} phosphor was synthesized by the combustion method. The X-ray powder diffraction (XRD) analysis confirmed that the phosphor powder crystallized as orthorhombic structure belonging to space group Cmcm. From Williamson-Hall analysis the grain size and microstrain in the powder was estimated. The Fourier- transform infrared (FT-IR) studies further validated the formation of vanadate phase of the phosphor. Photoluminescence (PL) study revealed that the phosphor could be efficiently excited by UV-VIS from 200 nm to 500 nm. The 565 nm, 602 nm, 648 nm and 713 nm emissions were ascribed to {sup 4}G{sub 5/2} to {sup 6}H{sub J} (J = 5/2, 7/2, 9/2 and 11/2) transitions of the Sm{sup 3+} ion. The present material may be explored as a novel phosphor to be excited by UV light emitting diodes (LEDs) chips for solid-state lighting and display applications.

TiO{sub 2}/WO{sub 3} photoactive bilayers in the UV-Vis light region

Energy Technology Data Exchange (ETDEWEB)

Vasilaki, E. [University of Crete, Department of Chemistry, Heraklion, Crete (Greece); Technological Educational Institute of Crete, Center of Materials Technology and Photonics, School of Engineering, Heraklion, Crete (Greece); Vernardou, D. [Technological Educational Institute of Crete, Center of Materials Technology and Photonics, School of Engineering, Heraklion, Crete (Greece); Kenanakis, G.; Katsarakis, N. [Technological Educational Institute of Crete, Center of Materials Technology and Photonics, School of Engineering, Heraklion, Crete (Greece); Foundation for Research and Technology-Hellas, Institute of Electronic Structure and Laser, Vassilika Vouton, P.O. Box 1385, Heraklion, Crete (Greece); Vamvakaki, M. [Foundation for Research and Technology-Hellas, Institute of Electronic Structure and Laser, Vassilika Vouton, P.O. Box 1385, Heraklion, Crete (Greece); University of Crete, Department of Materials Science and Technology, Heraklion, Crete (Greece)

2017-04-15

In this work, photoactive bilayered films consisting of anatase TiO{sub 2} and monoclinic WO{sub 3} were synthesized by a sol-gel route. Titanium isopropoxide and tungsten hexachloride were used as metal precursors and deposition was achieved by spin-coating on Corning glass substrates. The samples were characterized by X-ray diffraction, photoluminescence, UV-Vis, and Raman spectroscopy, as well as field emission scanning electron microscopy. The prepared immobilized catalysts were tested for their photocatalytic performance by the decolorization of methylene blue in aqueous matrices, under UV-Vis light irradiation. The annealing process influenced the crystallinity of the bilayered films, while the concentration of the tungsten precursor solution and the position of the tungsten trioxide layer further affected their photocatalytic performance. In particular, the photocatalytic performance of the bilayered films was optimized at a concentration of 0.1 M of the WO{sub 3} precursor solution, when deposited as an overlying layer on TiO{sub 2} by two annealing steps (∝76% methylene blue decolorization in 300 min of irradiation versus ∝59% in the case of a bare TiO{sub 2} film). In general, the coupled layer catalysts exhibited superior photoactivity compared to that of bare TiO{sub 2} films with WO{sub 3} acting as an electron trap, resulting, therefore, in a more efficient electron-hole separation and inhibiting their recombination. (orig.)

CuS/RGO hybrid photocatalyst for full solar spectrum photoreduction from UV/Vis to near-infrared light.

Science.gov (United States)

Wu, Jie; Liu, Baibai; Ren, Zhenxing; Ni, Mengying; Li, Can; Gong, Yinyan; Qin, Wei; Huang, Yongli; Sun, Chang Q; Liu, Xinjuan

2018-05-01

To make full use of the solar energy, it remains a great challenge for semiconductor photocatalysts to harvest the full solar light spectrum from ultraviolet (UV) to visible even the near infrared (NIR) wavelength. Here we show firstly the CuS/RGO (reduced graphene oxide) hybrid photocatalyst synthesized via a microwave assisted method with full solar light (UV-Vis-NIR) active for efficient Cr(VI) reduction. The CuS/RGO displays high absorption and catalytic activity in the UV, visible and even the NIR light regions. As co-catalyst, RGO can separate and inhibit the recombination of charge carriers, consequently improving the catalytic activity. Only 1wt% RGO emersions can reduce 90% of Cr(VI) under the radiation of light over the full spectrum. Findings may provide a new strategy and substance to expand the utilization range of solar light from UV to visible even the NIR energy. Copyright © 2017. Published by Elsevier Inc.

Maceration of Extra Virgin Olive Oil with Common Aromatic Plants Using Ultrasound-Assisted Extraction: An UV-Vis Spectroscopic Investigation

Directory of Open Access Journals (Sweden)

Ozren Jović

2018-01-01

Full Text Available Rosemary (Rosmarinus officinalis, garden sage (Salvia officinalis, summer savory (Satureja hortensis, laurel (Laurus nobilis, and other aromatic plants were put in olive oil and exposed to ultrasounds for different duration. Filtrated oils were dissolved in cyclohexane, and UV-Vis measurements were carried out. Absorbance values corresponding to chlorophylls, carotenoids, flavonoids (370 nm, and polyphenols (around 300 nm were measured. In addition, for some samples, total phenols were determined using Folin-Denis reagent and compared with the similar maceration procedure in water solvent (instead of olive oil. Maceration without ultrasound in olive oil for each plant was also compared with ultrasound-assisted extraction. The results show that significant amount of aromatic content can be extracted in olive oil by applying ultrasounds for only few minutes, especially for Salvia officinalis powder. The use of UV-Vis measurements is simple but enough to examine the extent of phenol content extraction through such maceration procedure.

Organic conjugated small molecule materials based optical probe for rapid, colorimetric and UV-vis spectral detection of phosphorylated protein in placental tissue.

Science.gov (United States)

Wang, Yanfang; Yang, Na; Liu, Yi

2018-04-05

A novel organic small molecule with D-Pi-A structure was prepared, which was found to be a promising colorimetric and ratiometric UV-vis spetral probe for detection of phosphorylated proteins with the help of tetravalent zirconium ion. Such optical probe based on chromophore WYF-1 shows a rapid response (within 10s) and high selectivity and sensitivity for phosphorylated proteins, giving distinct colorimetric and ratiometric UV-vis changes at 720 and 560nm. The detection limit for phosphorylated proteins was estimated to be 100nM. In addition, detection of phosphorylated proteins in placental tissue samples with this probe was successfully applied, which indicates that this probe holds great potential for phosphorylated proteins detection. Copyright © 2018 Elsevier B.V. All rights reserved.

A UV-Vis photoacoustic spectrophotometer.

Science.gov (United States)

Wiegand, Joseph R; Mathews, L Dalila; Smith, Geoffrey D

2014-06-17

A novel photoacoustic spectrophotometer (PAS) for the measurement of gas-phase and aerosol absorption over the UV-visible region of the spectrum is described. Light from a broadband Hg arc lamp is filtered in eight separate bands from 300 to 700 nm using bandpass interference filters (centered at 301 nm, 314 nm, 364 nm, 405 nm, 436 nm, 546 nm, 578 and 687 nm) and modulated with an optical chopper before entering the photoacoustic cell. All wavelength bands feature a 20-s detection limit of better than 3.0 Mm(-1) with the exception of the lower-intensity 687 nm band for which it is 10.2 Mm(-1). Validation measurements of gas-phase acetone and nigrosin aerosol absorption cross sections at several wavelengths demonstrate agreement to within 10% with those measured previously (for acetone) and those predicted by Mie theory (for nigrosin). The PAS instrument is used to measure the UV-visible absorption spectrum of ambient aerosol demonstrating a dramatic increase in the UV region with absorption increasing by 300% from 405 to 301 nm. This type of measurement throughout the UV-visible region and free from artifacts associated with filter-based methods has not been possible previously, and we demonstrate its promise for classifying and quantifying different types of light-absorbing ambient particles.

Thermal edible oil evaluation by UV-Vis spectroscopy and chemometrics.

Science.gov (United States)

Gonçalves, Rhayanna P; Março, Paulo H; Valderrama, Patrícia

2014-11-15

Edible oils such as colza, corn, sunflower, soybean and olive were analysed by UV-Vis spectroscopy and Multivariate Curve Resolution with Alternating Least Squares (MCR-ALS). When vegetable oils were heated at high temperatures (frying), oxidation products were formed which were harmful to human health in addition to degrading the antioxidants present, and this study aimed to evaluate tocopherol (one antioxidant present in oils) and the behaviour of oxidation products in edible oils. The MCR-ALS results showed that the degradation started at 110°C and 85°C, respectively, for sunflower and colza oils, while tocopherol concentration decreased and oxidation products increased starting at 70°C in olive oil. In soybean and corn oils, tocopherol concentration started to decrease and oxidation products increased at 50°C. The results suggested that sunflower, colza and olive oils offered more resistance to increasing temperatures, while soybean and corn oils were less resistant. Copyright © 2014 Elsevier Ltd. All rights reserved.

The effect of different propolis harvest methods on its lead contents determined by ET AAS and UV-visS

Energy Technology Data Exchange (ETDEWEB)

Sales, A. [Department of Analytical Chemistry, Faculty of Biochemistry, Chemistry and Pharmacy, National University of Tucuman, Ayacucho 471, 4000 Tucuman (Argentina)]. E-mail: amsales@fbqf.unt.edu.ar; Alvarez, A. [National Institute of Agricultural Technology (INTA), Experimental Station Famailla, Ruta 301, Km 32, Famailla, Tucuman (Argentina); Areal, M. Rodriguez [Department of Analytical Chemistry, Faculty of Biochemistry, Chemistry and Pharmacy, National University of Tucuman, Ayacucho 471, 4000 Tucuman (Argentina); Maldonado, L. [National Institute of Agricultural Technology (INTA), Experimental Station Famailla, Ruta 301, Km 32, Famailla, Tucuman (Argentina); Marchisio, P. [Department of Analytical Chemistry, Faculty of Biochemistry, Chemistry and Pharmacy, National University of Tucuman, Ayacucho 471, 4000 Tucuman (Argentina); Rodriguez, M. [Department of Analytical Chemistry, Faculty of Biochemistry, Chemistry and Pharmacy, National University of Tucuman, Ayacucho 471, 4000 Tucuman (Argentina); Bedascarrasbure, E. [National Institute of Agricultural Technology (INTA), Experimental Station Famailla, Ruta 301, Km 32, Famailla, Tucuman (Argentina)

2006-10-11

Argentinean propolis is exported to different countries, specially Japan. The market demands propolis quality control according to international standards. The analytical determination of some metals, as lead in food, is very important for their high toxicity even in low concentrations and because of their harmful effects on health. Flavonoids, the main bioactive compounds of propolis, tend to chelate metals as lead, which becomes one of the main polluting agents of propolis. The lead found in propolis may come from the atmosphere or it may be incorporated in the harvest, extraction and processing methods. The aim of this work is to evaluate lead level on Argentinean propolis determined by electrothermal atomic absorption spectrometry (ET AAS) and UV-vis spectrophotometry (UV-visS) methods, as well as the effect of harvest methods on those contents. A randomized test with three different treatments of collection was made to evaluate the effect of harvest methods. These procedures were: separating wedges (traditional), netting plastic meshes and stamping out plastic meshes. By means of the analysis of variance technique for multiple comparisons (ANOVA) it was possible to conclude that there are significant differences between scraped and mesh methods (stamped out and mosquito netting meshes). The results obtained in the present test would allow us to conclude that mesh methods are more advisable than scraped ones in order to obtain innocuous and safe propolis with minor lead contents. A statistical comparison of lead determination by both, ET AAS and UV-visS methods, demonstrated that there is not a significant difference in the results achieved with the two analytical techniques employed.

The Structure of p-Aminobenzoic Acid in Water: Studies Combining UV-Vis, NEXAFS and RIXS Spectroscopies

International Nuclear Information System (INIS)

Gainar, A; Stevens, J S; Schroeder, S L M; Suljoti, E; Xiao, J; Golnak, R; Aziz, E F

2016-01-01

NEXAFS-RIXS and home laboratory-based UV-Vis absorption spectroscopy are combined to examine the speciation and electronic structure of para -aminobenzoic acid (PABA) in aqueous solution as a function of pH. DFT and TD-DFT electronic structure calculations reproduce the experimental trends and provide a correlation between the experimental HOMO↔LUMO gap as well as the electronic transitions between molecular orbitals in the non-ionic, anionic and cationic forms of PABA. (paper)

Inter-laboratory comparisons of hexenuronic acid measurements in kraft eucalyptus pulps using a UV-Vis spectroscopic method

Science.gov (United States)

J.Y. Zhu; H.F Zhou; Chai X.S.; Donna Johannes; Richard Pope; Cristina Valls; M. Blanca Roncero

2014-01-01

An inter-laboratory comparison of a UV-Vis spectroscopic method (TAPPI T 282 om-13 “Hexeneuronic acid content of chemical pulp”) for hexeneuronic acid measurements was conducted using three eucalyptus kraft pulps. The pulp samples were produced in a laboratory at kappa numbers of approximately 14, 20, and 35. The hexeneuronic acid contents of the three pulps were...

Tunable ultraviolet solid-state dye laser based on MPMMA doped with pyrromethene 597

International Nuclear Information System (INIS)

Jiang, Y G; Fan, R W; Xia, Y Q; Chen, D Y

2011-01-01

Solid-state dye sample based on modified polymethyl methacrylate (MPMMA) co-doped with pyrromethene 597 (PM597), and coumarin 460 (C460) were prepared. A frequency-doubled pulsed Nd:YAG laser is used to pump solid-state dye sample, and the narrow linewidth dye laser of 94.4 mJ was obtained at 582 nm in an oscillator-amplifier configuration. Using a beta-BaB 2 O 4 (BBO) crystal to frequency double the dye laser into ultraviolet (UV), a tuning range from 279 to 305 nm was demonstrated from a single doped PM597 dye. To the best of our knowledge, the UV tuning range is the best under the same condition so far. The conversion slope efficiency from solid dye laser to UV laser was 8.9% and the highest UV laser output energy reached 6.94 mJ at 291 nm

Effects of gamma radiation on commercial food packaging films--study of changes in UV/VIS spectra

International Nuclear Information System (INIS)

Moura, E.A.B.; Ortiz, A.V.; Wiebeck, H.; Paula, A.B.A.; Silva, A.L.A.; Silva, L.G.A.

2004-01-01

The effects of gamma irradiation doses up to 100 kGy on the optical properties of different commercial packaging films were studied in this paper. The packaging films analyzed were: polyethylene 'LDPE', amide 6-amide 6.6 copolymer 'PA6-PA6.6' and poly(ethylene terephthalate) 'PET'. An investigation on film samples before and after irradiation was performed by UV/VIS spectroscopy. The results showed that, in the absorption spectra of irradiated LDPE and PA6-PA6.6 films, a red-shift in the wavelength of the UV cutoff and a marked reduction in % transmittance (at low wavelengths) occur with increasing radiation dose. With respect to PET samples, no significant changes were observed in either light absorption or transmittance

Ag_3PO_4 Microcrystals Synthesized by Room-Temperature Solid State Reaction: Enhanced Photocatalytic Activity and Photoelectronchemistry Performance

International Nuclear Information System (INIS)

Hao Chen-Chun; Xu Jie; Shi Hong-Long; Fu Jun-Li; Zou Bin; Meng Shan; Wang Wen-Zhong; Jia Ying

2015-01-01

Ag_3PO_4 microcrystals with highly enhanced visible light photocatalytic activity are prepared by a facile and simple solid state reaction at room temperature. The composition, morphology and optical properties of the as-prepared Ag_3PO_4 microcrystals are characterized by x-ray diffraction, scanning electron microscopy and UV-vis diffuse reflectance spectra. The photocatalytic properties of Ag_3PO_4 are investigated by the degradation of both methylene blue and methyl orange dyes under visible light irradiation. The as-prepared Ag_3PO_4 microcrystals possess high photocatalytic oxygen production with the rate of 673 μmolh"−"1 g"−"1. Moreover, the as-prepared Ag_3PO_4 microcrystals show an enhanced photoelectrochemistry performance under irradiation of visible light. (paper)

Formic acid enhanced effective degradation of methyl orange dye in aqueous solutions under UV-Vis irradiation.

Science.gov (United States)

Wang, Jingjing; Bai, Renbi

2016-09-15

Developing efficient technologies to treat recalcitrant organic dye wastewater has long been of great research and practical interest. In this study, a small molecule, formic acid (FA), was applied as a process enhancer for the degradation of methyl orange (MO) dye as a model recalcitrant organic pollutant in aqueous solutions under the condition of UV-Vis light irradiation and air aeration at the ambient temperature of 25 °C. It was found that the decolouration of the dye solutions can be rapidly achieved, reducing the time, for example, from around 17.6 h without FA to mostly about less than 2 h with the presence of FA. The mineralization rate of MO dye reached as high as 81.8% in 1.5 h in the case of initial MO dye concentration at 25 mg L(-1), which is in contrast to nearly no mineralization of the MO dye for a similar system without the FA added. The study revealed that the generation of the H2O2 species in the system was enhanced and the produced OH radicals effectively contributed to the degradation of the MO dye. Process parameters such as the initial concentration of MO dye, FA dosage and solution pH were all found to have some effect on the degradation efficiency under the same condition of UV-Vis light irradiation and air aeration. The MO dye degradation performance was found to follow a first-order reaction rate to the MO dye concentration in most cases and there existed a positive correlation between the reaction rate constant and the initial FA concentration. Compared to the traditional H2O2/UV-Vis oxidation system, the use of FA as a process-enhancing agent can have the advantages of low cost, easy availability, and safe to use. The study hence demonstrates a promising approach to use a readily available small molecule of FA to enhance the degradation of recalcitrant organic pollutants, such as MO dye, especially for their pre-treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Synthesis and XRD, FT-IR vibrational, UV-vis, and nonlinear optical exploration of novel tetra substituted imidazole derivatives: A synergistic experimental-computational analysis

Science.gov (United States)

Ahmad, Muhammad Saeed; Khalid, Muhammad; Shaheen, Muhammad Ashraf; Tahir, Muhammad Nawaz; Khan, Muhammad Usman; Braga, Ataualpa Albert Carmo; Shad, Hazoor Ahmad

2018-04-01

Heterocyclic compounds have potential applications in many fields of life. We synthesized novel tetra substituted imidazoles by four-component condensation of benzil, substituted aldehydes, substituted anilines and ammonium acetate as a source of ammonia and acetic acid as the solvent. Their chemical structures were resolved through X-ray crystallographic and spectroscopic (Fourier transform IR and UV-vis) techniques. In addition to experimental analysis, density functional theory (DFT) calculations at the B3LYP/6-311 + G(d,p) level were performed on 4-bromo-2-(1-(4-methoxyphenyl)-4,5-diphenyl-1H-imidazole-2-yl)phenol (1), 4-bromo-2-(1-(1-naphthalen-yl)-4,5-diphenyl-1H-imidazole-2-yl)phenol (2), and 2-(1-(2-chlorophenyl)-4,5-diphenyl-1-H-imidazole-2-yl)-6-methoxyphenol (3) to obtain the optimized geometry and spectroscopic (Fourier transform IR and UV-vis) and non-linear optical properties. Frontier molecular orbital analysis was performed at the Hartee-Fock/6-311+g(d,p) and DFT/B3LYP/6-311+G(d,p) levels of theory. Natural bond orbital (NBO) and UV-vis spectral analyses were performed at the M06-2X/6-31+G(d,p) and time-dependent DFT/B3LYP/6-311+G(d,p) levels, respectively. Overall, the DFT findings show good agreement with the experimental data. The hyper conjugative interaction network, which is responsible for the stability of compounds 1, 2 and 3 was explored by the NBO approach. The global reactivity parameters were explored with use of the energy of the frontier molecular orbitals. DFT calculations predict the first-order hyperpolarizabilities of compounds 1, 2 and 3 are 294.89 × 10-30, 219.45 × 10-30 and 146.77 × 10-30 esu, respectively. A two-state model was used to describe the non-linear optical properties of the compounds investigated.

Oligophenylenevinylenes in spatially confined nanochannels: Monitoring intermolecular interactions by UV/Vis and Raman spectroscopy

DEFF Research Database (Denmark)

Aloshyna, Mariya; Medina, Begona Milian; Poulsen, Lars

2008-01-01

-guest interactions are elucidated by UV/Vis and Raman spectroscopy. The impact of the local environment of the chromophore on the optical and photophysical properties is discussed in light of quantum-chemical calculations. In stark contrast to thin films where preferential side-by-side orientation leads to quenching...... of photoluminescence (PL) via non-emissive traps, the ICs are found to be attractive materials for opto-electronic applications: they offer high chromophore concentrations, but at the same time behave as quasi-isolated entities of tightly packed, well-oriented objects with high PL quantum yields and the possibility...

A fluorescent chemosensor for Zn(II). Exciplex formation in solution and the solid state.

Science.gov (United States)

Bencini, Andrea; Berni, Emanuela; Bianchi, Antonio; Fornasari, Patrizia; Giorgi, Claudia; Lima, Joao C; Lodeiro, Carlos; Melo, Maria J; de Melo, J Seixas; Parola, Antonio Jorge; Pina, Fernando; Pina, Joao; Valtancoli, Barbara

2004-07-21

The macrocyclic phenanthrolinophane 2,9-[2,5,8-triaza-5-(N-anthracene-9-methylamino)ethyl]-[9]-1,10-phenanthrolinophane (L) bearing a pendant arm containing a coordinating amine and an anthracene group forms stable complexes with Zn(II), Cd(II) and Hg(II) in solution. Stability constants of these complexes were determined in 0.10 mol dm(-3) NMe(4)Cl H(2)O-MeCN (1:1, v/v) solution at 298.1 +/- 0.1 K by means of potentiometric (pH metric) titration. The fluorescence emission properties of these complexes were studied in this solvent. For the Zn(II) complex, steady-state and time-resolved fluorescence studies were performed in ethanol solution and in the solid state. In solution, intramolecular pi-stacking interaction between phenanthroline and anthracene in the ground state and exciplex emission in the excited state were observed. From the temperature dependence of the photostationary ratio (I(Exc)/I(M)), the activation energy for the exciplex formation (E(a)) and the binding energy of the exciplex (-DeltaH) were determined. The crystal structure of the [ZnLBr](ClO(4)).H(2)O compound was resolved, showing that in the solid state both intra- and inter-molecular pi-stacking interactions are present. Such interactions were also evidenced by UV-vis absorption and emission spectra in the solid state. The absorption spectrum of a thin film of the solid complex is red-shifted compared with the solution spectra, whereas its emission spectrum reveals the unique featureless exciplex band, blue shifted compared with the solution. In conjunction with X-ray data the solid-state data was interpreted as being due to a new exciplex where no pi-stacking (full overlap of the pi-electron cloud of the two chromophores - anthracene and phenanthroline) is observed. L is a fluorescent chemosensor able to signal Zn(II) in presence of Cd(II) and Hg(II), since the last two metal ions do not give rise either to the formation of pi-stacking complexes or to exciplex emission in solution.

Solid-State Synthesis and Effect of Temperature on Optical Properties of CuO Nanoparticles

Institute of Scientific and Technical Information of China (English)

C.C.Vidyasagar; Y.Arthoba Naik; T.G.Venkatesha; R.Viswanatha

2012-01-01

Modulation of band energies through size control offers new ways to control photoresponse and photoconversion efficiency of the solar cell. The P-type semiconductor of copper oxide is an important functional material used for photovoltaic cells. Cu O is attractive as a selective solar absorber since it has high solar absorbance and a low thermal emittance. The present work describes the synthesis and characterization of semiconducting Cu O nanoparticles via one-step, solid-state reaction in the presence of Polyethylene glycol400 as size controlling agent for the preparation of Cu O nanoparticles at different temperatures. Solid-state mechanochemical processing, which is not only a physical size reduction process in conventional milling but also a chemical reaction, is mechanically activated at the nanoscale during grinding. The present method is a simple and efficient method of preparing nanoparticles with high yield at low cost. The structural and chemical composition of the nanoparticles were analyzed by X-ray diffraction, field emission scanning electron microscopy and energy-dispersive spectrometer, respectively. Optical properties and band gap of Cu O nanoparticles were studied by UV-Vis spectroscopy. These results showed that the band gap energy decreased with increase of annealing temperature, which can be attributed to the improvement in grain size of the samples.

The Catalytic Conversion of Thiophenes over Large H-ZSM-5 Crystals: An X-Ray, UV/Vis, and Fluorescence Microspectroscopic Study

NARCIS (Netherlands)

Kox, M.H.F.; Mijovilovich, A.E.; S ättler, J.J.H.B.; Stavitski, I.; Weckhuysen, B.M.

2013-01-01

X-ray absorption, UV/Vis, and fluorescence microspectroscopy have been used to characterize the catalytic conversion of thiophene derivatives within the micropores of an individual H-ZSM-5 zeolite crystal. Space-resolved information into the Si/ Al ratios and sulfur content was provided by X-ray

UV/VIS spektrofotometrie a možnosti jejího využití v rámci vzdělávání učitelů chemie

OpenAIRE

Hejsková, Veronika

2016-01-01

This master's thesis discusses the use of UV/VIS spectrophotometry in chemistry teacher education. Optical methods principles are described in theoretical part of the thesis, and. the main part is dedicated to UV-VIS spectrophotometry. Tasks for quantifying and qualifying substances determination are described in experimental part. Educational tasks are described in a way so that chemistry teachers could use for instructions.

Quantification of Coffea arabica and Coffea canephora var. robusta concentration in blends by means of synchronous fluorescence and UV-Vis spectroscopies.

Science.gov (United States)

Dankowska, A; Domagała, A; Kowalewski, W

2017-09-01

The potential of fluorescence, UV-Vis spectroscopies as well as the low- and mid-level data fusion of both spectroscopies for the quantification of concentrations of roasted Coffea arabica and Coffea canephora var. robusta in coffee blends was investigated. Principal component analysis was used to reduce data multidimensionality. To calculate the level of undeclared addition, multiple linear regression (PCA-MLR) models were used with lowest root mean square error of calibration (RMSEC) of 3.6% and root mean square error of cross-validation (RMSECV) of 7.9%. LDA analysis was applied to fluorescence intensities and UV spectra of Coffea arabica, canephora samples, and their mixtures in order to examine classification ability. The best performance of PCA-LDA analysis was observed for data fusion of UV and fluorescence intensity measurements at wavelength interval of 60nm. LDA showed that data fusion can achieve over 96% of correct classifications (sensitivity) in the test set and 100% of correct classifications in the training set, with low-level data fusion. The corresponding results for individual spectroscopies ranged from 90% (UV-Vis spectroscopy) to 77% (synchronous fluorescence) in the test set, and from 93% to 97% in the training set. The results demonstrate that fluorescence, UV, and visible spectroscopies complement each other, giving a complementary effect for the quantification of roasted Coffea arabica and Coffea canephora var. robusta concentration in blends. Copyright © 2017 Elsevier B.V. All rights reserved.

XRD, lead equivalent and UV-VIS properties study of Ce and Pr lead silicate glasses

International Nuclear Information System (INIS)

Alias, Nor Hayati; Abdullah, Wan Shafie Wan; Isa, Norriza Mohd; Isa, Muhammad Jamal Md; Zali, Nurazila Mat; Abdullah, Nuhaslinda Ee; Muhammad, Azali

2014-01-01

In this work, Cerium (Ce) and Praseodymium (Pr) containing lead silicate glasses were produced with 2 different molar ratios low (0.2 wt%) and high (0.4wt%). These types of glasses can satisfy the characteristics required for radiation shielding glasses and minimize the lead composition in glass. The radiation shielding properties of the synthesized glasses is explained in the form of lead equivalent study. The XRD diffraction and UV-VIS analysis were performed to observe the structural changes of the synthesis glasses at 1.5 Gy gamma radiation exposures

A comparative UV-vis-diffuse reflectance study on the location and interaction of cerium ions in Al- and Zr-pillared montmorillonite clays

International Nuclear Information System (INIS)

Rao, G. Ranga; Mishra, Braja Gopal

2005-01-01

The environment, location and interaction of the Ce 3+ ions in the micropores of Al- and Zr-pillared clays have been studied by UV-vis-diffuse reflectance spectroscopy (UV-vis-DRS). The DRS spectra show that the chemical environment of the Ce 3+ ions in cerium exchanged clay is different from that of the Al- and Zr-pillared clays. The Al-Ce pillared clays (Al-Ce-PM) show four distinct absorption bands at 224, 263, 294 and 342 nm in the UV region which are attributed to 4f → 5d interconfigurational transitions of Ce 3+ ions associated with alumina pillars. The O 2- → Ce 3+ charge transfer band observed at 263 nm for Ce-exchanged and Al-Ce-PM clays is blue shifted by 10 nm for Ce-Zr-pillared clays (Ce-Zr-PM) due to fully hydrated Ce 3+ ions. The Ce 3+ ions are incorporated in the Al- and Zr-pillars possibly as AlCeO 3 and Ce x Zr 1-x O 2 particles upon heat treatment

Using resonance light scattering and UV/vis absorption spectroscopy to study the interaction between gliclazide and bovine serum albumin.

Science.gov (United States)

Zhang, Qiu-Ju; Liu, Bao-Sheng; Li, Gai-Xia; Han, Rong

2016-08-01

At different temperatures (298, 310 and 318 K), the interaction between gliclazide and bovine serum albumin (BSA) was investigated using fluorescence quenching spectroscopy, resonance light scattering spectroscopy and UV/vis absorption spectroscopy. The first method studied changes in the fluorescence of BSA on addition of gliclazide, and the latter two methods studied the spectral change in gliclazide while BSA was being added. The results indicated that the quenching mechanism between BSA and gliclazide was static. The binding constant (Ka ), number of binding sites (n), thermodynamic parameters, binding forces and Hill's coefficient were calculated at three temperatures. Values for the binding constant obtained using resonance light scattering and UV/vis absorption spectroscopy were much greater than those obtained from fluorescence quenching spectroscopy, indicating that methods monitoring gliclazide were more accurate and reasonable. In addition, the results suggest that other residues are involved in the reaction and the mode 'point to surface' existed in the interaction between BSA and gliclazide. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Hydrogen bond controlled adduct formation of meso-tetra(4-sulfonatophenyl)porphyrin with protic acids: a UV-vis spectroscopic study.

Science.gov (United States)

Zakavi, Saeed; Rahiminezhad, Hajar; Alizadeh, Robabeh

2010-12-01

Interaction of meso-tetra(4-sulfonatophenyl)porphyrin (H2tppS4) with weak and strong protic acid have been studied by UV-vis spectroscopy in water, dichloromethane and methanol. Different shifts of the Soret and Q(0,0) bands in the three solvents, the aggregation of diprotonated species and the stability of porphyrin-acid adducts in the solution, may be explained by the inter- and intramolecular hydrogen bonds. Whilst, the addition of excess amounts of tetra-n-butylammonium chloride to H2tppS4(Cl)2 in dichloromethane has little to no effect on the UV-vis spectrum of the dication, gradual addition of tetra-n-butylammonium hydrogen sulfate to the dichloromethane solution of H2tppS4(H2SO4)2 leads to the degradation of adducts and the release of porphryin. The results of this study clearly show the crucial role played by hydrogen bonds between the porphyrin diprotonated species and the counter ion in the stability of porphyrin diacids in solution. Copyright © 2010 Elsevier B.V. All rights reserved.

Identification of Intermediates in Zeolite-Catalyzed Reactions Using In-situ UV/Vis Micro- Spectroscopy and a Complementary Set of Molecular Simulations

NARCIS (Netherlands)

Hemelsoet, K.L.J.; Qian, Q.|info:eu-repo/dai/nl/34138609X; De Meyer, T.; De Wispelaere, K.; De Sterck, B.; Weckhuysen, B.M.|info:eu-repo/dai/nl/285484397; Waroquier, M.; Van Speybroeck, V.

2013-01-01

The optical absorption properties of (poly)aromatic hydrocarbons occluded in a nanoporous environment were investigated by theoretical and experimental methods. The carbonaceous species are an essential part of a working catalyst for the methanol-toolefins (MTO) process. In situ UV/Vis microscopy

VUV and UV–vis optical study on KGd2F7 luminescent host doped with terbium and co-doped with europium

International Nuclear Information System (INIS)

Lisiecki, Radosław

2013-01-01

The KGd 2 F 7 :Tb and KGd 2 F 7 :Tb,Eu samples were obtained using a solid state reaction. Excitation spectra and emission spectra are reported and analyzed within the VUV–UV–vis spectral range. The intense green luminescence is observed in the KGd 2 F 7 :Tb while the combined emission of terbium and europium in the KGd 2 F 7 :Tb,Eu covers substantially the region of white light. The materials under study can be effectively excited making use of intense f–d transitions of Tb 3+ in the VUV–UV region. Experimental lifetimes of luminescent levels have been measured and discussed. It was found that the considerable energy transfer from Tb 3+ to Eu 3+ occurs. -- Highlights: • The prospective green and white emitting phosphors. • The effective VUV and UV–vis excitation process. • The considerable energy transfer among optically active ions. • The influence of (Tb, Eu) co-doping on relaxation dynamic of excited states

Detection of Outliers and Imputing of Missing Values for Water Quality UV-VIS Absorbance Time Series

OpenAIRE

Plazas-Nossa, Leonardo; Ávila Angulo, Miguel Antonio; Torres, Andrés

2017-01-01

Context:The UV-Vis absorbance collection using online optical captors for water quality detection may yield outliers and/or missing values. Therefore, pre-processing to correct these anomalies is required to improve the analysis of monitoring data. The aim of this study is to propose a method to detect outliers as well as to fill-in the gaps in time series. Method:Outliers are detected using Winsorising procedure and the application of the Discrete Fourier Transform (DFT) and the Inverse of F...

Modified Fe3O4- hydroxyapatite nanocomposites as heterogeneous catalysts in three UV, Vis and Fenton like degradation systems

Science.gov (United States)

Valizadeh, S.; Rasoulifard, M. H.; Dorraji, M. S. Seyed

2014-11-01

The magnetite-hydroxyapatite (M-HAP) nanocomposites were prepared by a chemical co- precipitation procedure and characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and diffuse reflectance spectra (DRS). The ability of the synthesized catalyst for photocatalytic degradation of Acid Blue 25 (AB25), as an organic dye, under UV irradiation was studied. The catalyst was modified employing transition metals (Mn, Fe, Co, Ni, Cu and Zn) trying to improve the catalytic performance of HAP in absence of UV irradiation and in the presence of hydrogen peroxide i.e. a Fenton like reaction. The best results obtained for Cu and Co modified M-HAPs and the effect of operational parameters such pH, amount of catalyst and hydrogen peroxide concentration was studied. In order to investigate the performance of HAP based photocatalyst in visible light region, M-HAP was modified with silver ions. At the end, Langmuir-Hinshelwood kinetic expression used to evaluate and compare the catalytic systems. The strongest degradation activity was observed for Ag-M-HAP/Vis system because of Ag3PO4 formation. Apparent reaction rate constant (Kapp) by Ag-M-HAP/Vis was 63, 36 and 19 times faster than Cu-M-HAP(II)/H2O2, Co-M-HAP(II)/H2O2 and M-HAP (I)/UV systems, respectively.

UV-VIS and photoluminescence spectroscopy for nanomaterials characterization

CERN Document Server

2013-01-01

Second volume of a 40-volume series on nanoscience and nanotechnology, edited by the renowned scientist Challa S.S.R. Kumar. This handbook gives a comprehensive overview about UV-visible and photoluminescence spectroscopy for the characterization of nanomaterials. Modern applications and state-of-the-art techniques are covered and make this volume essential reading for research scientists in academia and industry in the related fields.

UV-Vis/FT-NIR in situ monitoring of visible-light induced polymerization of PEGDA hydrogels initiated by eosin/triethanolamine/O2.

Science.gov (United States)

Kaastrup, Kaja; Aguirre-Soto, Alan; Wang, Chen; Bowman, Christopher N; Stansbury, Jeffery; Sikes, Hadley D

In conjunction with a tertiary amine coinitiator, eosin, a photoreducible dye, has been shown to successfully circumvent oxygen inhibition in radical photopolymerization reactions. However, the role of O 2 in the initiation and polymerization processes remains inconclusive. Here, we employ a UV-Vis/FT-NIR analytical tool for real-time, simultaneous monitoring of chromophore and monomer reactive group concentrations to investigate the eosin-activated photopolymerization of PEGDA-based hydrogels under ambient conditions. First, we address the challenges associated with spectroscopic monitoring of the polymerization of hydrogels using UV-Vis and FT-NIR, proposing metrics for quantifying the extent of signal loss from reflection and scattering, and showing their relation to microgelation and network formation. Second, having established a method for extracting kinetic information by eliminating the effects of changing refractive index and scattering, the coupled UV-Vis/FT-NIR system is applied to the study of eosin-activated photopolymerization of PEGDA in the presence of O 2 . Analysis of the inhibition time, rate of polymerization, and rate of eosin consumption under ambient and purged conditions indicates that regeneration of eosin in the presence of oxygen and consumption of oxygen occur via a nonchain process. This suggests that the uniquely high O 2 resilience is due to alternative processes such as energy transfer from photo-activated eosin to oxygen. Uncovering the intricacies of the role of O 2 in eosin-mediated initiation aids the design of O 2 resistant free radical polymerization systems relevant to photonics, optoelectronics, biomaterials, and biosensing.

Laboratory spectroscopy of meteorite samples at UV-vis-NIR wavelengths: Analysis and discrimination by principal components analysis

Science.gov (United States)

Penttilä, Antti; Martikainen, Julia; Gritsevich, Maria; Muinonen, Karri

2018-02-01

Meteorite samples are measured with the University of Helsinki integrating-sphere UV-vis-NIR spectrometer. The resulting spectra of 30 meteorites are compared with selected spectra from the NASA Planetary Data System meteorite spectra database. The spectral measurements are transformed with the principal component analysis, and it is shown that different meteorite types can be distinguished from the transformed data. The motivation is to improve the link between asteroid spectral observations and meteorite spectral measurements.

Study of PVDF/Graphene oxide nanocomposites by UV-Vis analysis

International Nuclear Information System (INIS)

Pereira, Juliana V.

2013-01-01

In this work we have prepared nanocomposites made by mixing Poly (vinylidene fluoride) [PVDF] and grapheme oxide nanosheets (GO) aiming to find dosimetric properties for applications in high dose dosimetry. Graphene Oxides (GO) nanosheets were synthesized by the Hummers method, using graphite supplied by Aldrich as the starting material. Nanocomposites were produced by mixing solved PDVF in DMAc with GO dispersed in an aqueous solution by sonication. The samples were irradiated with a Co-60 source at constant dose rate (12 kGy/h), with doses ranging from 50 to 1,000 kGy. The UV-Vis and spectrophotometry have been used to monitor the appearing of C=C conjugated bonds and radio-oxidation of carbon (C=O). The PVDF/OG nanocomposites prepared with 1.88 at.% of OG presented the best dosimetric properties. In this material, UVVis spectrometry has revealed that the absorbance intensities at 250 nm can be used for high dosimetry purposes for gamma doses ranging from 100 to 750 kGy. In this range, it is possible to observe a linear relationship between Abs and Dose. (author)

UV-VIS Spectroscopy Applied to Stratospheric Chemistry, Methods and Results

Energy Technology Data Exchange (ETDEWEB)

Karlsen, K.

1996-03-01

This paper was read at the workshop ``The Norwegian Climate and Ozone Research Programme`` held on 11-12 March 1996. Numerous observations and modeling have shown with a very high degree of certainty that the man-made emissions of chlorofluorocarbons (CFC) and halons are responsible for the Antarctica ozone hole. It is also evident that the ozone layer of the Northern Hemisphere has suffered a certain decline over the last 10-15 years, possibly because of CFC and halons. 20-30% of the observed reduction is ascribed to coupled chlorine and bromine chemistry via a catalytic cycle resulting in the net conversion of 2O{sub 3} to 3O{sub 2}. But the details are not fully understood. The author plans to assemble a UV-VIS spectrometer for measuring the species OClO and BrO and to compare and discuss measured diurnal variations of OClO and BrO with model calculations. The use of Differential Optical Absorption Spectroscopy (DOAS) is discussed and some results from late 1995 presented. 6 refs., 2 figs.

Chemical composition and surfactant characteristics of marine foams investigated by means of UV-vis, FTIR and FTNIR spectroscopy.

Science.gov (United States)

Mecozzi, Mauro; Pietroletti, Marco

2016-11-01

In this study, we collected the ultraviolet-visible (UV-vis), Fourier transform infrared (FTIR) and Fourier transform near-infrared (FTNIR) spectra of marine foams from different sites and foams produced by marine living organisms (i.e. algae and molluscs) to retrieve information about their molecular and structural composition. UV-vis spectra gave information concerning the lipid and pigment contents of foams. FTIR spectroscopy gave a more detailed qualitative information regarding carbohydrates, lipids and proteins in addition with information about the mineral contents of foams. FTNIR spectra confirmed the presence of carbohydrates, lipids and proteins in foams. Then, due to the higher content of structural information of FTIR spectroscopy with respect to FTNIR and UV-vis, we join the FTIR spectra of marine foams to those of humic substance from marine sediments and to the spectra of foams obtained by living organisms. We submitted this resulting FTIR spectral dataset to statistical multivariate methods to investigate specific aspects of foams such as structural similarity among foams and in addition, contributions from the organic matter of living organisms. Cluster analysis (CA) evidenced several cases (i.e. clusters) of marine foams having high structural similarity with foams from vegetal and animal samples and with humic substance extracted from sediments. These results suggested that all the living organisms of the marine environment can give contributions to the chemical composition of foams. Moreover, as CA also evidenced cases of structural differences within foam samples, we applied two-dimensional correlation analysis (2DCORR) to the FTIR spectra of marine foams to investigate the molecular characteristics which caused these structural differences. Asynchronous spectra of two-dimensional correlation analysis showed that the structural heterogeneity among foam samples depended reasonably on the presence and on the qualitative difference of

Comparison of carrier transport mechanism under UV/Vis illumination in an AZO photodetector and an AZO/p-Si heterojunction photodiode produced by spray pyrolysis

International Nuclear Information System (INIS)

Shasti, M.; Mortezaali, A.; Dariani, R. S.

2015-01-01

In this study, Aluminum doped Zinc Oxide (AZO) layer is deposited on p-type silicon (p-Si) by spray pyrolysis method to fabricate ultraviolet-visible (UV/Vis) photodetector as Al doping process can have positive effect on the photodetector performance. Morphology, crystalline structure, and Al concentration of AZO layer are investigated by SEM, XRD, and EDX. The goal of this study is to analyze the mechanism of carrier transport by means of current-voltage characteristics under UV/Vis illumination in two cases: (a) electrodes connected to the surface of AZO layer and (b) electrodes connected to cross section of heterojunction (AZO/p-Si). Measurements indicate that the AZO/p-Si photodiode exhibits a higher photocurrent and lower photoresponse time under visible illumination with respect to AZO photodetector; while under UV illumination, the above result is inversed. Besides, the internal junction field of AZO/p-Si heterojunction plays an important role on this mechanism

Comparison of carrier transport mechanism under UV/Vis illumination in an AZO photodetector and an AZO/p-Si heterojunction photodiode produced by spray pyrolysis

Energy Technology Data Exchange (ETDEWEB)

Shasti, M.; Mortezaali, A., E-mail: mortezaali@alzahra.ac.ir; Dariani, R. S. [Department of Physics, Alzahra University, Tehran 1993893973 (Iran, Islamic Republic of)

2015-01-14

In this study, Aluminum doped Zinc Oxide (AZO) layer is deposited on p-type silicon (p-Si) by spray pyrolysis method to fabricate ultraviolet-visible (UV/Vis) photodetector as Al doping process can have positive effect on the photodetector performance. Morphology, crystalline structure, and Al concentration of AZO layer are investigated by SEM, XRD, and EDX. The goal of this study is to analyze the mechanism of carrier transport by means of current-voltage characteristics under UV/Vis illumination in two cases: (a) electrodes connected to the surface of AZO layer and (b) electrodes connected to cross section of heterojunction (AZO/p-Si). Measurements indicate that the AZO/p-Si photodiode exhibits a higher photocurrent and lower photoresponse time under visible illumination with respect to AZO photodetector; while under UV illumination, the above result is inversed. Besides, the internal junction field of AZO/p-Si heterojunction plays an important role on this mechanism.

Discrimination of Brazilian propolis according to the seasoning using chemometrics and machine learning based on UV-Vis scanning data.

Science.gov (United States)

Tomazzoli, Maíra M; Pai Neto, Remi D; Moresco, Rodolfo; Westphal, Larissa; Zeggio, Amelia R S; Specht, Leandro; Costa, Christopher; Rocha, Miguel; Maraschin, Marcelo

2015-12-01

Propolis is a chemically complex biomass produced by honeybees (Apis mellifera) from plant resins added of salivary enzymes, beeswax, and pollen. The biological activities described for propolis were also identified for donor plant's resin, but a big challenge for the standardization of the chemical composition and biological effects of propolis remains on a better understanding of the influence of seasonality on the chemical constituents of that raw material. Since propolis quality depends, among other variables, on the local flora which is strongly influenced by (a)biotic factors over the seasons, to unravel the harvest season effect on the propolis chemical profile is an issue of recognized importance. For that, fast, cheap, and robust analytical techniques seem to be the best choice for large scale quality control processes in the most demanding markets, e.g., human health applications. For that, UV-Visible (UV-Vis) scanning spectrophotometry of hydroalcoholic extracts (HE) of seventy-three propolis samples, collected over the seasons in 2014 (summer, spring, autumn, and winter) and 2015 (summer and autumn) in Southern Brazil was adopted. Further machine learning and chemometrics techniques were applied to the UV-Vis dataset aiming to gain insights as to the seasonality effect on the claimed chemical heterogeneity of propolis samples determined by changes in the flora of the geographic region under study. Descriptive and classification models were built following a chemometric approach, i.e. principal component analysis (PCA) and hierarchical clustering analysis (HCA) supported by scripts written in the R language. The UV-Vis profiles associated with chemometric analysis allowed identifying a typical pattern in propolis samples collected in the summer. Importantly, the discrimination based on PCA could be improved by using the dataset of the fingerprint region of phenolic compounds ( λ= 280-400 ηm), suggesting that besides the biological activities of those

Quality control of test iodine in urine by spectrophotometry UV-Vis

Science.gov (United States)

Huda, Thorikul; Nafisah, Durotun; Kumorowulan, Suryati; Lestari, Sri

2017-12-01

A quality control of iodine test in with UV-Vis spectrophotometry has been done. The purpose of this research is to find out whether the test results of samples conducted by Clinical Office of Research and Development Of GAKI (BP2GAKI) laboratory are still controlled, feasible and reliable, and still consistent over time, as indicated by the control chart. Quality control parameters are linearity, precision, accuracy, limit of detection, and limit of quantification. Based on the quality control that has been done, obtained linearity (r)= -0.9974, the detection limit and the limit of quantitation are respectively 2.26 µg/L and 7.54 µg/L, while the accuracy is calculated by %recovery and precision with value % RSD are 97.4161% and 1.7136% respectively. The quality control of iodine test in urine using the control chart shows excellent or stable results for 30 days and no variation of the results is very different for each day.

Enzyme Characterization in Microreactors by UV-Vis Spectroscopy

DEFF Research Database (Denmark)

Ringborg, Rolf Hoffmeyer; Krühne, Ulrich; Woodley, John

for selection can at this point be improved by characterization of the enzyme performance where also inhibition and toxicity effects are taken into account. Enzyme characterization is here defined as the effect on initial rate of reaction with respect to pH, enzyme, substrate, co-substrate, product and co......-product concentration [2]. From this investigation, it will be possible to determine whether the enzyme meets the criteria for process requirements or not. The development of the process will determine the requirements and this can also reach a state of maturity that resolves obstacles, lowers criteria and paves......, as the enzyme resource is scarce at this point of development. In the case where the reaction operates with UV active components, UV can be used to detect compounds with high sensitivity supplemented by multivariate data analysis. The spectra are here decorrelated and regressed to yield concentrations...

Size-selective precipitation in colloidal semiconductor nanocrystals of CdTe and CdSe: a study by UV-VIS spectroscopy; Precipitacao seletiva de tamanhos em nanoparticulas semicondutoras coloidais de CdTe e CdSe: um estudo por espectroscopia UV-VIS

Energy Technology Data Exchange (ETDEWEB)

Viol, Livia Cristina de Souza; Silva, Fernanda Oliveira; Ferreira, Diego Lourenconi; Alves, Jose Luiz Aarestrup; Schiavon, Marco Antonio, E-mail: schiavon@ufsj.edu.b [Universidade Federal de Sao Joao del Rei, MG (Brazil). Dept. de Ciencias Naturais

2011-07-01

The post-preparative size-selective precipitation technique was applied in CdTe and CdSe semiconductor nanocrystals prepared via colloidal route in water. The synthesis of CdTe and CdSe nanoparticles and the effect of the post-preparative size-selective precipitation have been characterized mainly by mean of ultraviolet and visible absorption spectroscopy (UV-Vis). It was demonstrated that the size-selective precipitation are able to isolate particles of different sizes and purify the nanoparticles as well. (author)

Investigation of Antioxidant Activity of Pomegranate Juices by Means of Electron Paramagnetic Resonance and UV-Vis Spectroscopy.

Science.gov (United States)

Kozik, Violetta; Jarzembek, Krystyna; Jędrzejowska, Agnieszka; Bąk, Andrzej; Polak, Justyna; Bartoszek, Mariola; Pytlakowska, Katarzyna

2015-01-01

Pomegranate fruit (Punica granatum L.) is a source of numerous phenolic compounds, and it contains flavonoids such as anthocyanins, anthocyanidins, cyanidins, catechins and other complexes of flavonoids, ellagitannins, and hydrolyzed tannins. Pomegranate juice shows antioxidant, antiproliferative, and anti-atherosclerotic properties. The antioxidant capacity (TEAC) of the pomegranate juices was measured using electron paramagnetic resonance (EPR) spectroscopy and 1,1-diphenyl-2-picrylhydrazyl (DPPH•) as a source of free radicals, and the total phenolic (TP) content was measured using UV-Vis spectroscopy. All the examined pomegranate juices exhibited relatively high antioxidant properties. The TEAC values determined by means of EPR spectroscopy using Trolox (TE) as a free radical scavenger were in the range of 463.12 to 1911.91 μmol TE/100 mL juice. The TP content measured by the Folin-Ciocalteu method, using gallic acid (GA) as a free radical scavenger, widely varied in the investigated pomegranate juice samples and ranged from 1673.62 to 5263.87 mg GA/1 L juice. The strongest antioxidant properties were observed with the fresh pomegranate juices obtained from the fruits originating from Israel, Lebanon, and Azerbaijan. Correlation analysis of numerical data obtained by means of EPR spectroscopy (TEAC) and UV-Vis spectroscopy (TP) gave correlation coefficient (r)=0.90 and determination coefficient (r2)=0.81 (P<0.05).

Predicting the Shifts of Absorption Maxima of Azulene Derivatives Using Molecular Modeling and ZINDO CI Calculations of UV-Vis Spectra

Science.gov (United States)

Patalinghug, Wyona C.; Chang, Maharlika; Solis, Joanne

2007-01-01

The deep blue color of azulene is drastically changed by the addition of substituents such as CH[subscript 3], F, or CHO. Computational semiempirical methods using ZINDO CI are used to model azulene and azulene derivatives and to calculate their UV-vis spectra. The calculated spectra are used to show the trends in absorption band shifts upon…

Solid-State Synthesis and Effect of Temp erature on Optical Prop erties of CuO Nanoparticles

Institute of Scientific and Technical Information of China (English)

C. C. Vidyasagar; Y. Arthoba Naik∗; T. G. Venkatesha; R. Viswanatha

2012-01-01

Modulation of band energies through size control offers new ways to control photoresponse and photoconversion efficiency of the solar cell. The P-type semiconductor of copper oxide is an important functional material used for photovoltaic cells. CuO is attractive as a selective solar absorber since it has high solar absorbance and a low thermal emittance. The present work describes the synthesis and characterization of semiconducting CuO nanoparticles via one-step, solid-state reaction in the presence of Polyethylene glycol 400 as size controlling agent for the preparation of CuO nanoparticles at different temperatures. Solid-state mechanochemical processing, which is not only a physical size reduction process in conventional milling but also a chemical reaction, is mechanically activated at the nanoscale during grinding. The present method is a simple and efficient method of preparing nanoparticles with high yield at low cost. The structural and chemical composition of the nanoparticles were analyzed by X-ray diffraction, field emission scanning electron microscopy and energy-dispersive spectrometer, respectively. Optical properties and band gap of CuO nanoparticles were studied by UV-Vis spectroscopy. These results showed that the band gap energy decreased with increase of annealing temperature, which can be attributed to the improvement in grain size of the samples.

LC-MS of Metmyoglobin at pH = 2: Separation and Characterization of Apomyoglobin and Heme by ESI-MS and UV-Vis

Science.gov (United States)

Stynes, Helen Cleary; Layo, Araceli; Smith, Richard W.

2004-01-01

The protein species of apomyoglobin (apoMb) and heme are freed and segregated from the aqueous protein solution of metmyoglobin by liquid chromatography, and are distinguished by UV-Vis absorption or electrospray ionization mass spectrometry (ESI-MS). This is an ingenious and effective approach to characterize apomyoglobin and heme, while students…

Spectral information (gas, liquid and solid phase from EUV-VUV-UV-Vis-NIR) and related data (e.g. information concerning publications on quantum yield studies or photolysis studies) from published papers

Science.gov (United States)

Noelle, A.; Hartmann, G. K.; Martin-Torres, F. J.

2010-05-01

The science-softCon "UV/Vis+ Spectra Data Base" is a non-profit project established in August 2000 and is operated in accordance to the "Open Access" definitions and regulations of the CSPR Assessment Panel on Scientific Data and Information (International Council for Science, 2004, HYPERLINK "http://www.science-softcon.de/spectra/cspr.pdf" ICSU Report of the CSPR Assessment Panel on Data and Information; ISBN 0-930357-60-4). The on-line database contains currently about 5600 spectra (from low to very high resolution, at different temperatures and pressures) and datasheets (metadata) of about 850 substances. Additional spectra/datasheets will be added continuously. In addition more than 250 links to on-line free available original publications are provided. The interdisciplinary of this photochemistry database provides a good interaction between different research areas. So, this database is an excellent tool for scientists who investigate on different fields such as atmospheric chemistry, astrophysics, agriculture, analytical chemistry, environmental chemistry, medicine, remote sensing, etc. To ensure the high quality standard of the fast growing UV/Vis+ Spectra Data Base an international "Scientific Advisory Group" (SAG) has been established in 2004. Because of the importance of maintenance of the database the support of the scientific community is crucial. Therefore we would like to encourage all scientists to support this data compilation project thru the provision of new or missing spectral data and information.

Molecular Engineering of UV/Vis Light-Emitting Diode (LED)-Sensitive Donor-π-Acceptor-Type Sulfonium Salt Photoacid Generators: Design, Synthesis, and Study of Photochemical and Photophysical Properties.

Science.gov (United States)

Wu, Xingyu; Jin, Ming; Xie, Jianchao; Malval, Jean-Pierre; Wan, Decheng

2017-11-07

A series of donor-π-acceptor-type sulfonium salt photoacid generators (PAGs) were designed and synthesized by systematically changing electron-donating groups, π-conjugated systems, electron-withdrawing groups, and the number of branches through molecular engineering. These PAGs can effectively decompose under UV/Vis irradiation from a light-emitting diode (LED) light source because of the matching absorption and emitting spectra of the LEDs. The absorption and acid-generation properties of these sulfonium salts were elucidated by UV/Vis spectroscopy and so forth. Results indicated that the PAG performance benefited from the introduction of strong electron-donating groups, specific π-conjugated structures, certain electron-withdrawing groups, or two-branched structures. Most sulfonium salts showed potential as photoinitiators under irradiation by a wide variety of UV and visible LEDs. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

UV/Vis/NIR spectral properties of triarylamines and their corresponding radical cations

International Nuclear Information System (INIS)

Amthor, Stephan; Noller, Bastian; Lambert, Christoph

2005-01-01

The one-electron oxidation potential of 10 triarylamines 1-10 with all permutations of chloro-, methoxy- and methyl-substituents in the three para-positions were determined by cyclic voltammetry. The half wave potential E 1/2 (I) of the first oxidation wave correlates linearly with the number of chloro- and methoxy-substituents. A high long-term stability of the first oxidation wave for all triarylamines was observed by multi-cycle thin-layer measurements. AM1-CISD derived values of the absorption energies are in good agreement with the experiments but differ strongly for the oscillator strengths as well as for neutral compounds 1-10 and their corresponding mono radical cations. The small solvent dependence of the experimental UV/Vis spectra in CH 2 Cl 2 and MeCN reflects a minor charge transfer (CT) character of the electronic transitions of neutral and cationic compounds

Optofluidic UV-Vis spectrophotometer for online monitoring of photocatalytic reactions.

Science.gov (United States)

Wang, Ning; Tan, Furui; Zhao, Yu; Tsoi, Chi Chung; Fan, Xudong; Yu, Weixing; Zhang, Xuming

2016-06-29

On-chip integration of optical detection units into the microfluidic systems for online monitoring is highly desirable for many applications and is also well in line with the spirit of optofluidics technology-fusion of optics and microfluidics for advanced functionalities. This paper reports the construction of a UV-Vis spectrophotometer on a microreactor, and demonstrates the online monitoring of the photocatalytic degradations of methylene blue and methyl orange under different flow rates and different pH values by detecting the intensity change and/or the peak shift. The integrated device consists of a TiO2-coated glass substrate, a PDMS micro-sized reaction chamber and two flow cells. By comparing with the results of commercial equipment, we have found that the measuring range and the sensitivity are acceptable, especially when the transmittance is in the range of 0.01-0.9. This integrated optofluidic device can significantly cut down the test time and the sample volume, and would provide a versatile platform for real-time characterization of photochemical performance. Moreover, its online monitoring capability may enable to access the usually hidden information in biochemical reactions like intermediate products, time-dependent processes and reaction kinetics.

Optofluidic UV-Vis spectrophotometer for online monitoring of photocatalytic reactions

Science.gov (United States)

Wang, Ning; Tan, Furui; Zhao, Yu; Tsoi, Chi Chung; Fan, Xudong; Yu, Weixing; Zhang, Xuming

2016-06-01

On-chip integration of optical detection units into the microfluidic systems for online monitoring is highly desirable for many applications and is also well in line with the spirit of optofluidics technology-fusion of optics and microfluidics for advanced functionalities. This paper reports the construction of a UV-Vis spectrophotometer on a microreactor, and demonstrates the online monitoring of the photocatalytic degradations of methylene blue and methyl orange under different flow rates and different pH values by detecting the intensity change and/or the peak shift. The integrated device consists of a TiO2-coated glass substrate, a PDMS micro-sized reaction chamber and two flow cells. By comparing with the results of commercial equipment, we have found that the measuring range and the sensitivity are acceptable, especially when the transmittance is in the range of 0.01-0.9. This integrated optofluidic device can significantly cut down the test time and the sample volume, and would provide a versatile platform for real-time characterization of photochemical performance. Moreover, its online monitoring capability may enable to access the usually hidden information in biochemical reactions like intermediate products, time-dependent processes and reaction kinetics.

Phosphonate self-assembled monolayers as organic linkers in solid-state quantum dot sensetized solar cells

KAUST Repository

Ardalan, Pendar

2010-06-01

We have employed X-ray photoelectron spectroscopy (XPS), ultraviolet-visible (UV-vis) spectroscopy, infrared (IR) spectroscopy, water contact angle (WCA) measurements, ellipsometry, and electrical measurements to study the effects of self-assembled monolayers (SAMs) with phosphonic acid headgroups on the bonding and performance of cadmium sulfide (CdS) solid-state quantum dot sensitized solar cells (QDSSCs). ∼2 to ∼6 nm size CdS quantum dots (QDs) were grown on the SAM-passivated TiO2 surfaces by successive ionic layer adsorption and reaction (SILAR). Our results show differences in the bonding of the CdS QDs at the TiO2 surfaces with a SAM linker. Moreover, our data indicate that presence of a SAM increases the CdS uptake on TiO2 as well as the performance of the resulting devices. Importantly, we observe ∼2 times higher power conversion efficiencies in the devices with a SAM compared to those that lack a SAM. © 2010 IEEE.

UV-Vis microspectrophotometry as a method of differentiation between cotton fibre evidence coloured with reactive dyes

Science.gov (United States)

Was-Gubala, Jolanta; Starczak, Roza

2015-05-01

The main purposes of this study was to assess the usefulness of microspectrophotometry (MSP), both in the ultraviolet (UV) and visible (Vis) range for discriminating single cotton fibres dyed with reactive dyes coming from the same manufacturer, as well as the possibility of evaluation of the concentration of dye in an examine fibre. This study utilised woven cotton fabrics dyed with different concentrations of one-compound reactive dyes with the commercial name Cibacron® (at present Novacron®) as the focus of the MSP analysis. The spectra were recorded in the UV-Vis range between 200 and 800 nm, in transmission mode. The results from this study illustrated that all of the analysed cotton samples dyed with reactive dyes were distinguishable between each other with the use of MSP, mostly in the visible, and also in ultraviolet range. The limit for applied MSP techniques was 0.18% of the concentration of a dye in the textile sample. The results indicate that based on the absorbance measurements for fibres constituting e.g. forensic traces it was not possible to estimate the concentration of the dye in the fibre because Beer's law did not obey. The intra-sample, and inter- sample variation, as well as dichroism effect in a case of a cotton fibres dyed with reactive dye were observed. On the basis of the results obtained for each analysed cotton sample, it was concluded that there was no correlation between colour uniformity in cotton fabric (changes in lightness, red/green and yellow/blue colour) and concentration of the reactive dye.

Determination of Uranium In UO2 And U3O8 Powder Using UV-VIS Spectrophotometry

International Nuclear Information System (INIS)

Natalia Adventini; Diah Dwiana Lestiani; Muhayatun; Endah Damastuti

2009-01-01

Lab. TAR PTNBR BATAN - Bandung has been accredited by National Accreditation Committee on May 2 nd , 2006 as a test laboratory with number LP-311-ID, has to maintain its laboratory performance by participating in a proficiency test. In this activity, the determination of uranium in 2 samples of UO 2 with A1 and A2 codes and other 2 samples of U 3 O 8 with B1 and B2 codes using UV-Vis spectrophotometry was carried out. Colouring method was used by reacting thiocyanate ion with the uranyl ion in acidic solution to develop a stable yellow colour of uranyl thiocyanate complex solution and measured at wavelength of 380 nm. The result gave that concentration of uranium in A1, A2, B1 and B2 samples were 77.95; 75.29; 64.58 and 63.69% respectively. The Z-score value for A samples was - 1.99, meanwhile for B samples the Z score value of between laboratory was −1.29 with intra laboratory was -1,09. It meant that Z-score values for both samples were in good category. From this result, it showed that UV-Vis spectrophotometry is one of the several methods that can be used to determine uranium in UO 2 and U 3 O 8 powder. The Lab. TAR’s proficiency test for determination of uranium in UO 2 and U 3 O 8 gave a good result and it was hoped to support BATAN's program in the nuclear fuel field. (author)

A multifrequency virtual spectrometer for complex bio-organic systems: vibronic and environmental effects on the UV/Vis spectrum of chlorophyll a.

Science.gov (United States)

Barone, Vincenzo; Biczysko, Malgorzata; Borkowska-Panek, Monika; Bloino, Julien

2014-10-20

The subtle interplay of several different effects means that the interpretation and analysis of experimental spectra in terms of structural and dynamic characteristics is a challenging task. In this context, theoretical studies can be helpful, and as such, computational spectroscopy is rapidly evolving from a highly specialized research field toward a versatile and widespread tool. However, in the case of electronic spectra (e.g. UV/Vis, circular dichroism, photoelectron, and X-ray spectra), the most commonly used methods still rely on the computation of vertical excitation energies, which are further convoluted to simulate line shapes. Such treatment completely neglects the influence of nuclear motions, despite the well-recognized notion that a proper account of vibronic effects is often mandatory to correctly interpret experimental findings. Development and validation of improved models rooted into density functional theory (DFT) and its time-dependent extension (TD-DFT) is of course instrumental for the optimal balance between reliability and favorable scaling with the number of electrons. However, the implementation of easy-to-use and effective procedures to simulate vibrationally resolved electronic spectra, and their availability to a wide community of users, is at least equally important for reliable simulations of spectral line shapes for compounds of biological and technological interest. Here, such an approach has been applied to the study of the UV/Vis spectra of chlorophyll a. The results show that properly tailored approaches are feasible for state-of-the-art computational spectroscopy studies, and allow, with affordable computational resources, vibrational and environmental effects on the spectral line shapes to be taken into account for large systems. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Five different colours solid-state fluorescence of azastilbenes: a new ...

Indian Academy of Sciences (India)

2016-08-26

Aug 26, 2016 ... Five push–pull azastilbene derivatives [R = −OH (1), −OCH3 (2), −OCH2CH3 (3), −N(CH3)2 (4) and −N(CH2CH3)2 (5)] have been synthesized and successfully characterized by 1H NMR, ultraviolet–visible (UV–Vis) and Fourier-transform infrared (FT-IR) spectroscopy. Compounds 1–5 possess solid-state ...

Photothermal Activation of Metal-Organic Frameworks Using a UV-Vis Light Source.

Science.gov (United States)

Espín, Jordi; Garzón-Tovar, Luis; Carné-Sánchez, Arnau; Imaz, Inhar; Maspoch, Daniel

2018-03-21

Metal-organic frameworks (MOFs) usually require meticulous removal of the solvent molecules to unlock their potential porosity. Herein, we report a novel one-step method for activating MOFs based on the photothermal effect induced by directly irradiating them with a UV-vis lamp. The localized light-to-heat conversion produced in the MOF crystals upon irradiation enables a very fast solvent removal, thereby significantly reducing the activation time to as low as 30 min and suppressing the need for time-consuming solvent-exchange procedures and vacuum conditions. This approach is successful for a broad range of MOFs, including HKUST-1, UiO-66-NH 2 , ZIF-67, CPO-27-M (M = Zn, Ni, and Mg), Fe-MIL-101-NH 2 , and IRMOF-3, all of which exhibit absorption bands in the light emission range. In addition, we anticipate that this photothermal activation can also be used to activate covalent organic frameworks (COFs).

Towards a NNORSY Ozone Profile ECV from European Nadir UV/VIS Measurements

Science.gov (United States)

Felder, Martin; Kaifel, Anton; Huckle, Roger

2010-12-01

The Neural Network Ozone Retrieval System (NNORSY) has been adapted and applied to several different satellite instruments, including the backscatter UV/VIS instruments ERS2-GOME, SCIAMACHY and METOP-GOME-2. The retrieved long term ozone field hence spans the years 1995 till now. To provide target data for training the neural networks, the lower parts of the atmosphere are sampled by ozone sondes from the WOUDC and SHADOZ data archives. Higher altitudes are covered by a variety of limb-sounding instruments, including the SAGE and POAM series, HALOE, ACE-FTS and AURA-MLS. In this paper, we show ozone profile time series over the entire time range to demonstrate the "out-of-the-box" consistency and homogeneity of our data across the three different nadir sounders, i.e. without any kind of tuning applied. These features of Essential Climate Variable (ECV) datasets [1] also lie at the heart of the recently announced ESA Climate Change Initiative, to which we hope to contribute in the near future.

Electronic structure and optical properties of solid C60

International Nuclear Information System (INIS)

Mattesini, M.; Ahuja, R.; Sa, L.; Hugosson, H.W.; Johansson, B.; Eriksson, O.

2009-01-01

The electronic structure and the optical properties of face-centered-cubic C 60 have been investigated by using an all-electron full-potential method. Our ab initio results show that the imaginary dielectric function for high-energy values looks very similar to that of graphite, revealing close electronic structure similarities between the two systems. We have also identified the origin of different peaks in the dielectric function of fullerene by means of the calculated electronic density of states. The computed optical spectrum compares fairly well with the available experimental data for the Vis-UV absorption spectrum of solid C 60 .

Solid-state chelation of metal ions by ethylenediaminetetraacetate intercalated in a layered double hydroxide.

Science.gov (United States)

Tarasov, Konstantin A; O'Hare, Dermot; Isupov, Vitaly P

2003-03-24

The solid-state chelation of transition metal ions (Co(2+), Ni(2+), and Cu(2+)) from aqueous solutions into the lithium aluminum layered double hydroxide ([LiAl(2)(OH)(6)]Cl x 0.5H(2)O or LDH) which has been pre-intercalated with EDTA (ethylenediaminetetraacetate) ligand has been investigated. The intercalated metal cations form [M(edta)](2)(-) complexes between the LDH layers as indicated by elemental analysis, powder X-ray diffraction, and IR and UV-vis spectroscopies. If metal chloride or nitrate salts are used in the reaction with the LDH then co-intercalation of either the Cl(-) or NO(3)(-) anions is observed. In the case of metal acetate salts the cations intercalate without the accompanying anion. This can be explained by the different intercalation selectivity of the anions in relation to the LDH. In the latter case the introduction of the positive charge into LDH structure was compensated for by the release from the solid of the equivalent quantity of lithium and hydrogen cations. Time-resolved in-situ X-ray diffraction measurements have revealed that the chelation/intercalation reactions proceed very quickly. The rate of the reaction found for nickel acetate depends on concentration as approximately k[Ni(Ac)(2)](3).

Preparation of perovskite type titanium-bearing blast furnace slag photocatalyst doped with sulphate and investigation on reduction Cr(VI) using UV-vis light

International Nuclear Information System (INIS)

Lei, X.F.; Xue, X.X.

2008-01-01

Perovskite type titanium-bearing blast furnace slag (TBBFS) and sulphate-modified titanium-bearing blast furnace slag (SO 4 2- /TBBFS) photocatalysts were prepared by the high-energy ball milling method at different calcination temperature. The photocatalysts were characterized by XRD, FTIR, UV-vis diffuse reflectance spectra and SEM measurements. The photocatalytic activities of the different catalysts were evaluated by the photocatalytic reduction of Cr(VI) under UV-vis light irradiation. For the photocatalytic reduction of Cr(VI), the photocatalytic activities of TBBFS catalysts were found to be strongly dependent of the calcination temperature and TBBFS calcined at 700 deg. C showed a higher photocatalytic activity compared to other TBBFS catalysts. In contrast, sulphation of TBBFS improved the photocatalytic activities of SO 4 2- /TBBFS catalysts. At low calcination temperature, the photocatalytic activities of SO 4 2- /TBBFS catalysts were markedly higher than TBBFS prepared under high calcination temperature, suggesting that the presence of surface SO 4 2- favored the photocatalytic reduction of Cr(VI)

A new on-axis micro-spectrophotometer for combining Raman, fluorescence and UV/Vis absorption spectroscopy with macromolecular crystallography at the Swiss Light Source

Science.gov (United States)

Pompidor, Guillaume; Dworkowski, Florian S. N.; Thominet, Vincent; Schulze-Briese, Clemens; Fuchs, Martin R.

2013-01-01

The combination of X-ray diffraction experiments with optical methods such as Raman, UV/Vis absorption and fluorescence spectroscopy greatly enhances and complements the specificity of the obtained information. The upgraded version of the in situ on-axis micro-spectrophotometer, MS2, at the macromolecular crystallography beamline X10SA of the Swiss Light Source is presented. The instrument newly supports Raman and resonance Raman spectroscopy, in addition to the previously available UV/Vis absorption and fluorescence modes. With the recent upgrades of the spectral bandwidth, instrument stability, detection efficiency and control software, the application range of the instrument and its ease of operation were greatly improved. Its on-axis geometry with collinear X-ray and optical axes to ensure optimal control of the overlap of sample volumes probed by each technique is still unique amongst comparable facilities worldwide and the instrument has now been in general user operation for over two years. PMID:23955041

A new on-axis micro-spectrophotometer for combining Raman, fluorescence and UV/Vis absorption spectroscopy with macromolecular crystallography at the Swiss Light Source.

Science.gov (United States)

Pompidor, Guillaume; Dworkowski, Florian S N; Thominet, Vincent; Schulze-Briese, Clemens; Fuchs, Martin R

2013-09-01

The combination of X-ray diffraction experiments with optical methods such as Raman, UV/Vis absorption and fluorescence spectroscopy greatly enhances and complements the specificity of the obtained information. The upgraded version of the in situ on-axis micro-spectrophotometer, MS2, at the macromolecular crystallography beamline X10SA of the Swiss Light Source is presented. The instrument newly supports Raman and resonance Raman spectroscopy, in addition to the previously available UV/Vis absorption and fluorescence modes. With the recent upgrades of the spectral bandwidth, instrument stability, detection efficiency and control software, the application range of the instrument and its ease of operation were greatly improved. Its on-axis geometry with collinear X-ray and optical axes to ensure optimal control of the overlap of sample volumes probed by each technique is still unique amongst comparable facilities worldwide and the instrument has now been in general user operation for over two years.

XRF and UV-Vis-NIR analyses of medieval wall paintings of al-Qarawiyyin Mosque (Morocco)

Science.gov (United States)

Fikri, I.; El Amraoui, M.; Haddad, M.; Ettahiri, A. S.; Bellot-Gurlet, L.; Falguères, C.; Lebon, M.; Nespoulet, R.; Ait Lyazidi, S.; Bejjit, L.

2018-05-01

Medieval wall painting fragments, taken at the medieval Mosque of al-Qarawiyyin in Fez, have been investigated by means of X-ray fluorescence and UV-Vis-NIR diffuse reflectance spectroscopies. The analyses permitted to determine the palette of pigments used by craftsmen of the time. Hematite or red ochre were used to obtain red brown colours, calcite for white, copper-based pigments for blue and blue-grey shades while a mixture of cinnabar, lead-based pigments and hematite was adopted to make red-orange colours. Furthermore, the analysis of mortars (external layer and plaster) on these wall painting samples revealed that they are composed mainly by calcite and sometimes by additional compounds such as quartz and gypsum.

UV-Visible Absorption Spectroscopy Enhanced X-ray Crystallography at Synchrotron and X-ray Free Electron Laser Sources.

Science.gov (United States)

Cohen, Aina E; Doukov, Tzanko; Soltis, Michael S

2016-01-01

This review describes the use of single crystal UV-Visible Absorption micro-Spectrophotometry (UV-Vis AS) to enhance the design and execution of X-ray crystallography experiments for structural investigations of reaction intermediates of redox active and photosensitive proteins. Considerations for UV-Vis AS measurements at the synchrotron and associated instrumentation are described. UV-Vis AS is useful to verify the intermediate state of an enzyme and to monitor the progression of reactions within crystals. Radiation induced redox changes within protein crystals may be monitored to devise effective diffraction data collection strategies. An overview of the specific effects of radiation damage on macromolecular crystals is presented along with data collection strategies that minimize these effects by combining data from multiple crystals used at the synchrotron and with the X-ray free electron laser.

Combination of UV-vis spectroscopy and chemometrics to understand protein-nanomaterial conjugate: a case study on human serum albumin and gold nanoparticles.

Science.gov (United States)

Wang, Yong; Ni, Yongnian

2014-02-01

Study of the interactions between proteins and nanomaterials is of great importance for understanding of protein nanoconjugate. In this work, we choose human serum albumin (HSA) and citrate-capped gold nanoparticles (AuNPs) as a model of protein and nanomaterial, and combine UV-vis spectroscopy with multivariate curve resolution by an alternating least squares (MCR-ALS) algorithm to present a new and efficient method for comparatively comprehensive study of evolution of protein nanoconjugate. UV-vis spectroscopy coupled with MCR-ALS allows qualitative and quantitative extraction of the distribution diagrams, spectra and kinetic profiles of absorbing pure species (AuNPs and AuNPs-HSA conjugate are herein identified) and undetectable species (HSA) from spectral data. The response profiles recovered are converted into the desired thermodynamic, kinetic and structural parameters describing the protein nanoconjugate evolution. Analysis of these parameters for the system gives evidence that HSA molecules are very likely to be attached to AuNPs surface predominantly as a flat monolayer to form a stable AuNPs-HSA conjugate with a core-shell structure, and the binding process takes place mainly through electrostatic and hydrogen-bond interactions between the positively amino acid residues of HSA and the negatively carboxyl group of citrate on AuNPs surface. The results obtained are verified by transmission electron microscopy, zeta potential, circular dichroism spectroscopy and Fourier transform infrared spectroscopy, showing the potential of UV-vis spectroscopy for study of evolution of protein nanoconjugate. In parallel, concentration evolutions of pure species resolved by MCR-ALS are used to construct a sensitive spectroscopic biosensor for HSA with a linear range from 1.8 nM to 28.1 nM and a detection limit of 0.8 nM. © 2013 Published by Elsevier B.V.

UV-Vis microspectrophotometry as a method of differentiation between cotton fibre evidence coloured with reactive dyes.

Science.gov (United States)

Was-Gubala, Jolanta; Starczak, Roza

2015-05-05

The main purposes of this study was to assess the usefulness of microspectrophotometry (MSP), both in the ultraviolet (UV) and visible (Vis) range for discriminating single cotton fibres dyed with reactive dyes coming from the same manufacturer, as well as the possibility of evaluation of the concentration of dye in an examine fibre. This study utilised woven cotton fabrics dyed with different concentrations of one-compound reactive dyes with the commercial name Cibacron® (at present Novacron®) as the focus of the MSP analysis. The spectra were recorded in the UV-Vis range between 200 and 800nm, in transmission mode. The results from this study illustrated that all of the analysed cotton samples dyed with reactive dyes were distinguishable between each other with the use of MSP, mostly in the visible, and also in ultraviolet range. The limit for applied MSP techniques was 0.18% of the concentration of a dye in the textile sample. The results indicate that based on the absorbance measurements for fibres constituting e.g. forensic traces it was not possible to estimate the concentration of the dye in the fibre because Beer's law did not obey. The intra-sample, and inter- sample variation, as well as dichroism effect in a case of a cotton fibres dyed with reactive dye were observed. On the basis of the results obtained for each analysed cotton sample, it was concluded that there was no correlation between colour uniformity in cotton fabric (changes in lightness, red/green and yellow/blue colour) and concentration of the reactive dye. Copyright © 2015 Elsevier B.V. All rights reserved.

Four Brazilian Maytenus salicifolia Reissek (Celastraceae groups studied by TLC and UV/Vis spectrophotometry

Directory of Open Access Journals (Sweden)

Frederico N. Valladão

Full Text Available The great variety of angiosperms shows the need to development of botanical classification systems supported by phytochemistry, biochemistry and others. Recently, techniques of analysis used for the isolation and characterization of secondary metabolites have been employed as auxiliary quick and efficient methods for the identification and classification of plant species. M. salicifolia is popularly known in Brazil, as "small coffee" and decoct obtained from its fresh leaves is topically used to alleviate itches and other skins allergic symptoms. This work presents the use of TLC and UV/Vis spectrophotomety processes to be applied like an auxiliary method in botanical taxonomy. The results demonstrate that this process can be used in differentiation of the same genera species, and in the selection of chemical variations between individuals of the same species.

Modified Fe3O4- hydroxyapatite nanocomposites as heterogeneous catalysts in three UV, Vis and Fenton like degradation systems

International Nuclear Information System (INIS)

Valizadeh, S.; Rasoulifard, M.H.; Dorraji, M.S. Seyed

2014-01-01

Graphical abstract: - Highlights: • Photocatalytic degradation of dye by Ag modified HAP under visible light. • Study of Fenton like degradation of dye by transition metal ions modified HAP. • Comparison of catalytic systems according to Langmuir-Hinshelwood kinetic expression. - Abstract: The magnetite-hydroxyapatite (M-HAP) nanocomposites were prepared by a chemical co- precipitation procedure and characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and diffuse reflectance spectra (DRS). The ability of the synthesized catalyst for photocatalytic degradation of Acid Blue 25 (AB25), as an organic dye, under UV irradiation was studied. The catalyst was modified employing transition metals (Mn, Fe, Co, Ni, Cu and Zn) trying to improve the catalytic performance of HAP in absence of UV irradiation and in the presence of hydrogen peroxide i.e. a Fenton like reaction. The best results obtained for Cu and Co modified M-HAPs and the effect of operational parameters such pH, amount of catalyst and hydrogen peroxide concentration was studied. In order to investigate the performance of HAP based photocatalyst in visible light region, M-HAP was modified with silver ions. At the end, Langmuir-Hinshelwood kinetic expression used to evaluate and compare the catalytic systems. The strongest degradation activity was observed for Ag-M-HAP/Vis system because of Ag 3 PO 4 formation. Apparent reaction rate constant (K app ) by Ag-M-HAP/Vis was 63, 36 and 19 times faster than Cu-M-HAP(II)/H 2 O 2 , Co-M-HAP(II)/H 2 O 2 and M-HAP (I)/UV systems, respectively

Solid-State Spectroscopy An Introduction

CERN Document Server

Kuzmany, Hans

2009-01-01

Spectroscopic methods have opened up a new horizon in our knowledge of solid-state materials. Numerous techniques using electromagnetic radiation or charged and neutral particles have been invented and worked out to a high level in order to provide more detailed information on the solids. The text presented here is an updated description of such methods as they were originally presented in the first edition. It covers linear response of solids to electromagnetic radiation in a frequency range extending from megahertz or gigahertz as used in spin resonance spectroscopy, to infrared spectroscopy and various forms of spectroscopy in the visible and near visible spectral range. It extends to spectroscopy in the UV and x-ray spectral range and eventually several spectroscopic methods are addressed in the frequency range of g radiation. Likewise linear response to irradiation with particles such as electrons, positrons, muons, neutrons, and atoms is discussed. Instrumental and technical background is provided as we...

UV-vis spectra as an alternative to the Lowry method for quantify hair damage induced by surfactants.

Science.gov (United States)

Pires-Oliveira, Rafael; Joekes, Inés

2014-11-01

It is well known that long term use of shampoo causes damage to human hair. Although the Lowry method has been widely used to quantify hair damage, it is unsuitable to determine this in the presence of some surfactants and there is no other method proposed in literature. In this work, a different method is used to investigate and compare the hair damage induced by four types of surfactants (including three commercial-grade surfactants) and water. Hair samples were immersed in aqueous solution of surfactants under conditions that resemble a shower (38 °C, constant shaking). These solutions become colored with time of contact with hair and its UV-vis spectra were recorded. For comparison, the amount of extracted proteins from hair by sodium dodecyl sulfate (SDS) and by water were estimated by the Lowry method. Additionally, non-pigmented vs. pigmented hair and also sepia melanin were used to understand the washing solution color and their spectra. The results presented herein show that hair degradation is mostly caused by the extraction of proteins, cuticle fragments and melanin granules from hair fiber. It was found that the intensity of solution color varies with the charge density of the surfactants. Furthermore, the intensity of solution color can be correlated to the amount of proteins quantified by the Lowry method as well as to the degree of hair damage. UV-vis spectrum of hair washing solutions is a simple and straightforward method to quantify and compare hair damages induced by different commercial surfactants. Copyright © 2014 Elsevier B.V. All rights reserved.

Adsorption characteristics of Au nanoparticles onto poly(4-vinylpyridine) surface revealed by QCM, AFM, UV/vis, and Raman scattering spectroscopy.

Science.gov (United States)

Kim, Kwan; Ryoo, Hyunwoo; Lee, Yoon Mi; Shin, Kuan Soo

2010-02-15

In this work, we report that the adsorption and aggregation processes of Au nanoparticles on a polymer surface can be monitored by means of surface-enhanced Raman scattering (SERS) spectroscopy. Specifically, we were able to analyze the adsorption process of citrate-stabilized Au nanoparticles onto a film of poly(4-vinylpyridine) (P4VP) by taking a series of SERS spectra, during the self-assembly of Au nanoparticles onto the polymer film. In order to better analyze the SERS spectra, we separately conducted quartz crystal microbalance (QCM), UV/vis spectroscopy, and atomic force microscope (AFM) measurements. The adsorption kinetics revealed by QCM under the in situ conditions was in fair agreement with that determined by the ex situ AFM measurement. The number of Au nanoparticles adsorbed on P4VP increased almost linearly with time: 265 Au nanoparticles per 1microm(2) were adsorbed on the P4VP film after 6h of immersion. The SERS signal measured in the ex situ condition showed a more rapid increase than that of QCM; however, its increasing pattern was quite similar to that of UV/vis absorbance at longer wavelengths, suggesting that Au nanoparticles actually became agglomerated on P4VP. Copyright 2009 Elsevier Inc. All rights reserved.

[Fe₃O₄-β-Cyclodextrin Polymer Nano Composites Solid-Phase Extraction-UV-Vis Spectrophotometry for Separation Analysis Malachite Green].

Science.gov (United States)

Feng, Gang; Ping, Wen-hui; Zhu, Xia-shi

2016-02-01

In this paper, carboxymethyl-hydroxypropyl-β-cyclodextrin polymer modified magnetic particles Fe₃O₄ (CM-HP-β-CD- CP-MNPs) were prepared and applied to magnetic solid phase extraction of malachite green combined with UV-Visible spectrom- etry detection. The synthesized magnetic particles were characterized by element analysis, Fourier transform infrared spectra and transmission electron microscopy. Several variables affecting the extraction and desorption of malachite green such as pH, the amount of adsorbent, the type and volume of eluent, extraction and desorption time, and temperature were investigated. Under the optimum conditions, malachite green could be adsorbed by CM-HP-β-CDCP-MNPs (RE% = 92), and elution by C₂H₅OH (EE% = 90). the preconcentration factor of the proposed method was approximately 7.5, the CM-HP-β-CDCP-MNPs could be used repeatedly for 5 times and offered better recovery. The linear range and detection limit (DL) were found to be 0.08~8.00 µg · mL⁻¹ and 5.6 ng · mL⁻¹ respectively. This technique had been successfully applied to the determination of malachite green in real samples. The inclusion interaction of CM-HP--CDCP-MNPs with malachite green was studied through FTIR.

UV-vis, IR and 1H NMR spectroscopic studies and characterization of ionic-pair crystal violet-oxytetracycline

Science.gov (United States)

Orellana, Sandra; Soto, César; Toral, M. Inés

2010-01-01

The present study shows the formation and characterization of the ionic-pair between the antibiotic oxytetracycline and the dye crystal violet in ammonia solution pH 9.0 ± 0.2 extracted into chloroform. The characterization was demonstrated using UV-vis spectrophotometry, 1H NMR, measurement of relaxation times T1 and IR spectroscopy, using a comparison between the signals of individual pure compounds with the signals with the mixture CV-OTC in different alkaline media. The formation of ionic-pair was also corroborated by new signals and chemical shifts. (2D) NMR spectroscopy experiments show that the interaction is electrostatic.

UV-Vis optoelectronic properties of α-SnWO4: A comparative experimental and density functional theory based study

KAUST Repository

Ziani, Ahmed

2015-09-03

We report a combined experimental and theoretical study on the optoelectronic properties of α-SnWO4 for UV-Vis excitation. The experimentally measured values for thin films were systematically compared with high-accuracy density functional theory and density functional perturbation theory using the HSE06 functional. The α-SnWO4 material shows an indirect bandgap of 1.52 eV with high absorption coefficient in the visible-light range (>2 × 105 cm−1). The results show relatively high dielectric constant (>30) and weak diffusion properties (large effective masses) of excited carriers.

Defects in UV-vis-NIR reflectance spectra as method for forgery detections in writing documents

Energy Technology Data Exchange (ETDEWEB)

Somma, F; Aloe, P; Schirripa Spagnolo, G

2010-11-01

Documents have taken up a very important place in our society. Frauds committed in connection with documents are not at all uncommon, and, in fact, represent a very large domain of the forensic science called 'questioned documents'. In the field of forensic examination of questioned documents, the legitimacy of an ink entry is often an essential question. A common type of forgery consists in materially altering an existing writing or adding a new writing. These changes can be characterized by means of optical spectroscopy. The aim of this work is to perform the UV-vis-NIR reflectance spectrophotometry to analyze a range of blue and black commercial ballpoint pens, in order to investigate the discriminating abilities of the different inks found on the same document.

Detection of olive oil adulteration by low-field NMR relaxometry and UV-Vis spectroscopy upon mixing olive oil with various edible oils; Detección de la adulteración de aceite de oliva mediante relaxometría magnética nuclear de campo bajo y espectroscopía UV-Vis sobre mezcla de aceite de oliva con diversos aceites comestibles.

Energy Technology Data Exchange (ETDEWEB)

Ok, S.

2017-07-01

Adulteration of olive oil using unhealthy substitutes is considered a threat for public health. Low-field (LF) proton (1H) nuclear magnetic resonance (NMR) relaxometry and ultra-violet (UV) visible spectroscopy are used to detect adulteration of olive oil. Three different olive oil with different oleoyl acyl contents were mixed with almond, castor, corn, and sesame oils with three volumetric ratios, respectively. In addition, Arbequina olive oil was mixed with canola, flax, grape seed, peanut, soybean, and sunflower seed oils with three volumetric ratios. Transverse magnetization relaxation time (T2) curves were fitted with bi-exponential decaying functions. T2 times of each mixture of olive oils and castor oils, and olive oils and corn oils changed systematically as a function of volumetric ratio. To detect the adulteration in the mixtures with almond and sesame oils, both LF 1H NMR relaxometry and UV-Vis spectroscopy were needed, where UV-Vis-spectroscopy detected the adulteration qualitatively. In the mixtures of Arbequina olive oil and flax, peanut, soybean, and sunflower seed oils, both T21 and T22 values became longer systematically as the content of the olive oil was decreased. The unique UV-Vis maximum absorbance of flax oil at 320.0 nm shows the adulteration of olive oil qualitatively. [Spanish] La adulteración del aceite de oliva con sustituyentes menos saludables es una amenaza para la salud pública. En este trabajo, la detección de la adulteración del aceite de oliva se demuestra utilizando tanto relaxometría magnética nuclear de campo bajo (LF) de protones (1H) (RMN) y espectroscopía visible y ultra-violeta (UV). Tres muestras de aceites de oliva con diferentes contenidos en oleico se mezclaron con aceites de almendra, ricino, maíz y sésamo con tres relaciones volumétricas. Además, el de arbequina de California se mezcló con cánola, lino, semilla de uva, cacahuete, soja y aceites de girasol con tres relaciones volumétricas. Las curvas de

Application of Photocured Polymer Ion Selective Membranes for Solid-State Chemical Sensors

Directory of Open Access Journals (Sweden)

Natalia Abramova

2015-06-01

Full Text Available Application of conducting polymers with additional functional groups for a solid contact formation and photocurable membranes as sensitive elements of solid-state chemical sensors is discussed. Problems associated with application of UV-curable polymers for sensors are analyzed. A method of sensor fabrication using copolymerized conductive layer and sensitive membrane is presented and the proof of concept is confirmed by two examples of solid-contact electrodes for Ca ions and pH.

Design progress of the solar UV-Vis-IR telescope (SUVIT) aboard SOLAR-C

Science.gov (United States)

Katsukawa, Y.; Ichimoto, K.; Suematsu, Y.; Hara, H.; Kano, R.; Shimizu, T.; Matsuzaki, K.

2013-09-01

We present a design progress of the Solar UV-Vis-IR Telescope (SUVIT) aboard the next Japanese solar mission SOLAR-C. SUVIT has an aperture diameter of ~1.4 m for achieving spectro-polarimetric observations with spatial and temporal resolution exceeding the Hinode Solar Optical Telescope (SOT). We have studied structural and thermal designs of the optical telescope as well as the optical interface between the telescope and the focal plane instruments. The focal plane instruments are installed into two packages, filtergraph and spectrograph packages. The spectropolarimeter is the instrument dedicated to accurate polarimetry in the three spectrum windows at 525 nm, 854 nm, and 1083 nm for observing magnetic fields at both the photospheric and chromospheric layers. We made optical design of the spectrograph accommodating the conventional slit spectrograph and the integral field unit (IFU) for two-dimensional coverage. We are running feasibility study of the IFU using fiber arrays consisting of rectangular cores.

Determination of Pu Oxidation states in the HCl Media Using with UV-Visible Absorption Spectroscopic Techniques

International Nuclear Information System (INIS)

Lee, Myung Ho; Suh, Mu Yeol; Park, Kyoung Kyun; Park, Yeong Jae; Kim, Won Ho

2006-01-01

The spectroscopic characteristics of Pu (III, IV, V, VI) in the HCl media were investigated by measuring Pu oxidation states using a UV-Vis-NIR spectrophotometer (400-1200 nm) after adjusting Pu oxidation states with oxidation/reduction reagents. Pu in stock solution was reduced to Pu(III) with NH 2 OH · HCl, and oxidized to Pu(IV) and Pu(VI) with NaNO 2 and HCIO 4 , respectively. Also, Pu(V) was adjusted in the Pu(VI) solution with NH 2 OH · HCl. The major absorption peaks of Pu (IV) and Pu(III) were measured in the 470 nm and 600 nm, respectively. The major absorption peaks of Pu (VI) and Pu(V) were measured in the 830 nm and 1135 nm, respectively. There was not found to be significant changes of UV-V is absorption spectra for Pu(III), Pu(IV) and Pu(VI) with aging time, except that an unstable Pu(V) immediately reduced to Pu(III).

Using UHPLC and UV-vis Fingerprint Method to Evaluate Substitutes for Swertia mileensis: An Endangered Medicinal Plant.

Science.gov (United States)

Li, Jie; Zhang, Ji; Jin, Hang; Wang, Yuan-Zhong; Huang, Heng-Yu

2017-01-01

exist are in leaves of S. davidii with the highest content.The obvious diversity in four plants was displayed from comprehensive point of view though similarity assay and PCA analysis.The UV fingerprint method offsets the defect that the UHPLC fingerprint reflected messages of secoiridoid glycosides only. Abbreviation used: UHPLC: Ultra high performance liquid chromatography, UV-vis: Ultraviolet-vis, HBV: Anti-hepatitis virus, DNA: Deoxyribonucleic acid, PCA: Principal component analysis, D-GaIN: D-Galactosamine, BCG: Bacille Calmette-Guerin, LPS: Lipopolysaccharide.

Unveiling the Aggregation of Lycopene in Vitro and in Vivo: UV-Vis, Resonance Raman, and Raman Imaging Studies.

Science.gov (United States)

Ishigaki, Mika; Meksiarun, Phiranuphon; Kitahama, Yasutaka; Zhang, Leilei; Hashimoto, Hideki; Genkawa, Takuma; Ozaki, Yukihiro

2017-08-31

The present study investigates the structure of lycopene aggregates both in vitro and in vivo using ultraviolet-visible (UV-vis) and Raman spectroscopies. The electronic absorption bands of the J- and H-aggregates in vitro shift to lower and higher energies, respectively, compared to that of the lycopene monomer. Along with these results, the frequencies of the ν 1 Raman bands were shifted to lower and higher frequencies, respectively. By plotting the frequencies of the ν 1 Raman band against the S 0 → S 2 transition energy, a linear relationship between the data set with different aggregation conformations can be obtained. Therefore, the band positions depending on the different conformations can be explained based on the idea that the effective conjugated C═C chain lengths within lycopene molecules are different due to the environmental effect (site-shift effect) caused by the aggregation conformation. Applying this knowledge to the in vivo measurement of a tomato fruit sample, the relationship between the aggregation conformation of lycopene and the spectral patterns observed in the UV-vis as well as Raman spectra in different parts of tomato fruits was discussed in detail. The results showed that the concentration of lycopene (particularly that of the J-aggregate) specifically increased, whereas that of chlorophyll decreased, with ripening. Furthermore, Raman imaging indicated that lycopene with different aggregate conformations was distributed inhomogeneously, even within one sample. The layer formation in tomato tissues with high concentrations of J- and H-aggregates was successfully visualized. In this manner, the presence of lycopene distributions with different aggregate conformations was unveiled in vivo.

Characterization of solid UV cross-linked PEGDA for biological applications

KAUST Repository

Castro, David; Ingram, Patrick; Kodzius, Rimantas; Conchouso Gonzalez, David; Yoon, Euisik; Foulds, Ian G.

2013-01-01

This paper reports on solid UV cross-linked Poly(ethylene)-glycol-diacrylate (PEGDA) as a material for microfluidic devices for biological applications. We have evaluated biocompatibility of PEGDA through two separate means: 1) by examining cell

Analysis of Fe species in zeolites by UV-VIS-NIR, IR spectra and voltammetry. Effect of preparation, Fe loading and zeolite type

Czech Academy of Sciences Publication Activity Database

Čapek, Libor; Kreibich, Viktor; Dědeček, Jiří; Grygar, Tomáš; Wichterlová, Blanka; Sobalík, Zdeněk; Martens, J. A.; Brosius, R.; Tokarová, V.

2005-01-01

Roč. 80, 1-3 (2005), s. 279-289 ISSN 1387-1811 R&D Projects: GA MŠk OC D15.20 Grant - others:European Union(XE) G5RD-CT-2001-00595 Institutional research plan: CEZ:AV0Z40400503 Keywords : Fe-zeolites * UV-VIS spectra * IR spectra * voltammetry * Fe complexes Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.355, year: 2005

UV-vis spectroscopy and colorimetric models for detecting anthocyanin-metal complexes in plants: An overview of in vitro and in vivo techniques.

Science.gov (United States)

Fedenko, Volodymyr S; Shemet, Sergiy A; Landi, Marco

2017-05-01

Although anthocyanin (ACN) biosynthesis is one of the best studied pathways of secondary metabolism in plants, the possible physiological and ecological role(s) of these pigments continue to intrigue scientists. Like other dihydroxy B-ring substituted flavonoids, ACNs have an ability to bind metal and metalloid ions, a property that has been exploited for a variety of purposes. For example, the metal binding ability may be used to stabilize ACNs from plant food sources, or to modify their colors for using them as food colorants. The complexation of metals with cyanidin derivatives can also be used as a simple, sensitive, cheap, and rapid method for determination concentrations of several metals in biological and environmental samples using UV-vis spectroscopy. Far less information is available on the ecological significance of ACN-metal complexes in plant-environment interactions. Metalloanthocyanins (protocyanin, nemophilin, commelinin, protodelphin, cyanosalvianin) are involved in the copigmentation phenomenon that leads to blue-pigmented petals, which may facilitate specific plant-pollinator interactions. ACN-metal formation and compartmentation into the vacuole has also been proposed to be part of an orchestrated detoxification mechanism in plants which experience metal/metalloid excess. However, investigations into ACN-metal interactions in plant biology may be limited because of the complexity of the analytical techniques required. To address this concern, here we describe simple methods for the detection of ACN-metal both in vitro and in vivo using UV-vis spectroscopy and colorimetric models. In particular, the use of UV-vis spectra, difference absorption spectra, and colorimetry techniques will be described for in vitro determination of ACN-metal features, whereas reflectance spectroscopy and colorimetric parameters related to CIE L * a * b * and CIE XYZ systems will be detailed for in vivo analyses. In this way, we hope to make this high-informative tool

In situ solid-state fabrication of hybrid AgCl/AgI/AgIO3 with improved UV-to-visible photocatalytic performance.

Science.gov (United States)

Xie, Jing; Cao, Yali; Jia, Dianzeng; Li, Yizhao; Wang, Kun; Xu, Hui

2017-09-28

The AgCl/AgI/AgIO 3 composites were synthesized through a one-pot room-temperature in situ solid-state approach with the feature of convenient and eco-friendly. The as-prepared composites exhibit superior photocatalytic performance than pure AgIO 3 for the degradation of methyl orange (MO) under both UV and visible light irradiation. The photodegradation rate toward MO of the AgCl/AgI/AgIO 3 photocatalyst can reach 100% after 12 min irradiation under UV light, or 85.4% after 50 min irradiation under visible light, being significantly higher than AgCl, AgI, AgIO 3 and AgI/AgIO 3 . In addition, the AgCl/AgI/AgIO 3 photocatalyst possesses strong photooxidation ability for the degradation of rhodamine B (RhB), methylene blue (MB), phenol, bisphenol A (BPA) and tetracycline hydrochloride under visible light irradiation. The reactive species capture experiments confirmed that the h + and •O 2- play an essential role during the photocatalytic process under UV light or visible light irradiation. The enhanced effect may be beneficial from the enhanced light adsorption in full spectrum and increased separation efficiency of photogenerated hole-electron pairs, which can be ascribed to the synergistic effect among AgCl, AgI and AgIO 3 nanoplates in AgCl/AgI/AgIO 3 composites.

Structural characterization and optical properties of Eu"2"+ and Dy"2"+ doped Sr_2SiO_4 phosphor by solid state reaction method

International Nuclear Information System (INIS)

Verma, Durga; Verma, Mohan L.; Upma; Patel, R.P.

2016-01-01

Thermoluminescence, SEM, FTIR Divalent dysprosium and europium doped strontium silicate (Sr_2SiO_4) phosphors were synthesized with the high-temperature solid-state reaction technique. The obtained phosphor was well characterized by powder X-ray diffraction, scanning electron microscopy, FTIR, UV-visible spectroscopy and thermoluminescence. The crystal structure of the prepared phosphor has an orthorhombic structure with space group Pnma. From scanning electron microscopy (SEM), agglomerations of particles were observed due to the high temperature synthesis process. The chemical composition of the sintered Sr_2SiO_4:Dy"2"+ and Sr_2SiO_4: Eu"2"+ phosphor was confirmed by energy dispersive X-ray spectroscopy (EDX). The UV-VIS analysis can be thought as a good quality check for the optical behavior of materials. The Fourier transmission infrared spectroscopy (FTIR) confirms the present elements in phosphor. Thermoluminescence study was carried out for the phosphor with UV irradiation show one glow peak. The trapping parameters associated with the prominent glow peak of Sr_2SiO_4:Dy"2"+ and Sr_2SiO_4:Eu"2"+ are calculated using Chen's glow curve method. The release of holes/electrons from defect centers at the characteristic trap site initiates the luminescence process in this material. (author)

UV-vis-NIR and EPR characterisation of the redox series [MQ3]2+,+,0,−,2−, M = Ru or Os, and Q = o-quinone derivative

Czech Academy of Sciences Publication Activity Database

Das, A. K.; Hübner, R.; Sarkar, B.; Fiedler, Jan; Záliš, Stanislav; Lahiri, G. K.; Kaim, W.

2012-01-01

Roč. 41, č. 29 (2012), s. 8913-8921 ISSN 1477-9226 R&D Projects: GA MŠk LD11086 Institutional support: RVO:61388955 Keywords : physical chemistry * EPR spectroscopy * UV-vis-NIR Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.806, year: 2012

Effect of Molecular Guest Binding on the d-d Transitions of Ni2+ of CPO-27-Ni: A Combined UV-Vis, Resonant-Valence-to-Core X-ray Emission Spectroscopy, and Theoretical Study.

Science.gov (United States)

Gallo, Erik; Gorelov, Evgeny; Guda, Alexander A; Bugaev, Aram L; Bonino, Francesca; Borfecchia, Elisa; Ricchiardi, Gabriele; Gianolio, Diego; Chavan, Sachin; Lamberti, Carlo

2017-12-04

We used Ni K-edge resonant-valence-to-core X-ray emission spectroscopy (RVtC-XES, also referred to as direct RIXS), an element-selective bulk-sensitive synchrotron-based technique, to investigate the electronic structure of the CPO-27-Ni metal-organic framework (MOF) upon molecular adsorption of significant molecular probes: H 2 O, CO, H 2 S, and NO. We compare RVtC-XES with UV-vis spectroscopy, and we show that the element selectivity of RVtC-XES is of strategic significance to observe the full set of d-d excitations in Ni 2+ , which are partially overshadowed by the low-energy π-π* transitions of the Ni ligands in standard diffuse-reflectance UV-vis experiments. Our combined RVtC-XES/UV-vis approach provides access to the whole set of d-d excitations, allowing us a complete discussion of the changes undergone by the electronic configuration of the Ni 2+ sites hosted within the MOF upon molecular adsorption. The experimental data have been interpreted by multiplet ligand-field theory calculations based on Wannier orbitals. This study represents a step further in understanding the ability of the CPO-27-Ni MOFs in molecular sorption and separation applications.

UV-vis in situ spectrometry data mining through linear and non linear analysis methods

Directory of Open Access Journals (Sweden)

Liliana López-Kleine

2014-01-01

Full Text Available Los espectrómetros UV-visibles son captores que registran la absorbancia de luz emitida por partículas suspendidas en el agua a diferentes longitudes de onda y proporcionan mediciones en continuo, las cuales pueden ser interpretadas como concentraciones de parámetros comúnmente usados para evaluar el estado físico-químico de cuerpos de agua. Parámetros clásicos usados para detectar la presencia de contaminación en el agua son los sólidos suspendidos totales (TSS y la demanda química de oxígeno (CDO. Métodos de análisis flexibles y eficientes son necesarios para extraer información útil para fines de gestión y monitoreo a partir de los datos multivariados que proporcionan los captores. Se han usado métodos de calibración de tipo regresión parcial por mínimos cuadrados parciales (PLS. Varios autores han demostrado la necesidad de realizar la calibración para cada tipo de datos y cada cuerpo de agua, así como explorar métodos de análisis lineales y no lineales para el análisis de datos UV-visible y para determinar su relación con parámetros clásicos. En este trabajo se aplican métodos de análisis multivariado lineales y no lineales para la minería de datos UV-vis de alta dimensión, los cuales resultan útiles para la identificación de relaciones entre parámetros y longitudes de onda, la detección de muestras atípicas, así como la detección de estructuras no lineales en los datos.

Applicability of UV laser-induced solid-state fluorescence spectroscopy for characterization of solid dosage forms.

Science.gov (United States)

Woltmann, Eva; Meyer, Hans; Weigel, Diana; Pritzke, Heinz; Posch, Tjorben N; Kler, Pablo A; Schürmann, Klaus; Roscher, Jörg; Huhn, Carolin

2014-10-01

High production output of solid pharmaceutical formulations requires fast methods to ensure their quality. Likewise, fast analytical procedures are required in forensic sciences, for example at customs, to substantiate an initial suspicion. We here present the design and the optimization of an instrumental setup for rapid and non-invasive characterization of tablets by laser-induced fluorescence spectroscopy (with a UV-laser (λ ex = 266 nm) as excitation source) in reflection geometry. The setup was first validated with regard to repeatability, bleaching phenomena, and sensitivity. The effect on the spectra by the physical and chemical properties of the samples, e.g. their hardness, homogeneity, chemical composition, and granule grain size of the uncompressed material, using a series of tablets, manufactured in accordance with design of experiments, was investigated. Investigation of tablets with regard to homogeneity, especially, is extremely important in pharmaceutical production processes. We demonstrate that multiplicative scatter correction is an appropriate tool for data preprocessing of fluorescence spectra. Tablets with different physical and chemical characteristics can be discriminated well from their fluorescence spectra by subjecting the results to principal component analysis.

UV-cured polymeric films containing ZnO and silver nanoparticles with UV–vis light-assisted photocatalytic activity

International Nuclear Information System (INIS)

Podasca, Viorica E.; Buruiana, Tinca; Buruiana, Emil C.

2016-01-01

Highlights: • Synthesis of photopolymerized films containing ZnO and/or Ag NPs is reported. • Photopolymerization of the acrylic monomers occurred with conversions of 57–90%. • XRD, EDX, and TEM analyses proved the uniform distribution of NPs in the matrix. • MB was photodegradated using the hybrid films under UV–vis irradiation. - Abstract: Hybrid polymer composites incorporating preformed ZnO alone or its mixture with Ag nanoparticles created during UV irradiation of some urethane acrylic monomers including trietoxysilylpropyl carbamoyloxyethyl methacrylate were synthesized and characterized by spectroscopic ("1H ("1"3C) NMR, FTIR, UV–vis, fluorescence, X-ray diffraction) and microscopic (AFM, ESEM/EDX, TEM) techniques. The results confirmed that the double bond conversion measured through FTIR spectroscopy varied in the range of 57–90% (after 60 s of irradiation), exhibiting formulation composition dependence. In the crosslinked polymer networks the existence of individual nanoparticles with primarily spherical shape and sizes between 5 and 15 nm for ZnO, and around 3 nm for in situ photogenerated silver nanoparticles was evidenced. Additionally, the photocatalytic effect of the photopolymerized hybrid films was investigated by determining the decomposition rate of the methylene blue (MB) in ethanol (over 90%) under UV (2.7 × 10"−"2 s"−"1) and visible irradiation (2.9 × 10"−"2 min"−"1). It was found that the composite films containing a higher amount of ZnO-Ag nanoparticles placed in water induced the photodecomposition of MB (∼87% after 100 min of visible irradiation; k = 2.1 × 10"−"2 min"−"1). The good efficiency of the NPs from these polymer films make them attractive for applications in photocatalysis of organic dye molecules.

UV-cured polymeric films containing ZnO and silver nanoparticles with UV–vis light-assisted photocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Podasca, Viorica E.; Buruiana, Tinca; Buruiana, Emil C., E-mail: emilbur@icmpp.ro

2016-07-30

Highlights: • Synthesis of photopolymerized films containing ZnO and/or Ag NPs is reported. • Photopolymerization of the acrylic monomers occurred with conversions of 57–90%. • XRD, EDX, and TEM analyses proved the uniform distribution of NPs in the matrix. • MB was photodegradated using the hybrid films under UV–vis irradiation. - Abstract: Hybrid polymer composites incorporating preformed ZnO alone or its mixture with Ag nanoparticles created during UV irradiation of some urethane acrylic monomers including trietoxysilylpropyl carbamoyloxyethyl methacrylate were synthesized and characterized by spectroscopic ({sup 1}H ({sup 13}C) NMR, FTIR, UV–vis, fluorescence, X-ray diffraction) and microscopic (AFM, ESEM/EDX, TEM) techniques. The results confirmed that the double bond conversion measured through FTIR spectroscopy varied in the range of 57–90% (after 60 s of irradiation), exhibiting formulation composition dependence. In the crosslinked polymer networks the existence of individual nanoparticles with primarily spherical shape and sizes between 5 and 15 nm for ZnO, and around 3 nm for in situ photogenerated silver nanoparticles was evidenced. Additionally, the photocatalytic effect of the photopolymerized hybrid films was investigated by determining the decomposition rate of the methylene blue (MB) in ethanol (over 90%) under UV (2.7 × 10{sup −2} s{sup −1}) and visible irradiation (2.9 × 10{sup −2} min{sup −1}). It was found that the composite films containing a higher amount of ZnO-Ag nanoparticles placed in water induced the photodecomposition of MB (∼87% after 100 min of visible irradiation; k = 2.1 × 10{sup −2} min{sup −1}). The good efficiency of the NPs from these polymer films make them attractive for applications in photocatalysis of organic dye molecules.

Modified Fe{sub 3}O{sub 4}- hydroxyapatite nanocomposites as heterogeneous catalysts in three UV, Vis and Fenton like degradation systems

Energy Technology Data Exchange (ETDEWEB)

Valizadeh, S., E-mail: valizadehsolmaz@yahoo.com; Rasoulifard, M.H., E-mail: m_h_rasoulifard@znu.ac.ir; Dorraji, M.S. Seyed, E-mail: dorraji@znu.ac.ir

2014-11-15

Graphical abstract: - Highlights: • Photocatalytic degradation of dye by Ag modified HAP under visible light. • Study of Fenton like degradation of dye by transition metal ions modified HAP. • Comparison of catalytic systems according to Langmuir-Hinshelwood kinetic expression. - Abstract: The magnetite-hydroxyapatite (M-HAP) nanocomposites were prepared by a chemical co- precipitation procedure and characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and diffuse reflectance spectra (DRS). The ability of the synthesized catalyst for photocatalytic degradation of Acid Blue 25 (AB25), as an organic dye, under UV irradiation was studied. The catalyst was modified employing transition metals (Mn, Fe, Co, Ni, Cu and Zn) trying to improve the catalytic performance of HAP in absence of UV irradiation and in the presence of hydrogen peroxide i.e. a Fenton like reaction. The best results obtained for Cu and Co modified M-HAPs and the effect of operational parameters such pH, amount of catalyst and hydrogen peroxide concentration was studied. In order to investigate the performance of HAP based photocatalyst in visible light region, M-HAP was modified with silver ions. At the end, Langmuir-Hinshelwood kinetic expression used to evaluate and compare the catalytic systems. The strongest degradation activity was observed for Ag-M-HAP/Vis system because of Ag{sub 3}PO{sub 4} formation. Apparent reaction rate constant (K{sub app}) by Ag-M-HAP/Vis was 63, 36 and 19 times faster than Cu-M-HAP(II)/H{sub 2}O{sub 2}, Co-M-HAP(II)/H{sub 2}O{sub 2} and M-HAP (I)/UV systems, respectively.

Thiol-thione tautomeric analysis, spectroscopic (FT-IR, Laser-Raman, NMR and UV-vis) properties and DFT computations of 5-(3-pyridyl)-4H-1,2,4-triazole-3-thiol molecule.

Science.gov (United States)

Gökce, Halil; Öztürk, Nuri; Ceylan, Ümit; Alpaslan, Yelda Bingöl; Alpaslan, Gökhan

2016-06-15

In this study, the 5-(3-pyridyl)-4H-1,2,4-triazole-3-thiol molecule (C7H6N4S) molecule has been characterized by using FT-IR, Laser-Raman, NMR and UV-vis spectroscopies. Quantum chemical calculations have been performed to investigate the molecular structure (thione-thiol tautomerism), vibrational wavenumbers, electronic transition absorption wavelengths in DMSO solvent and vacuum, proton and carbon-13 NMR chemical shifts and HOMOs-LUMOs energies at DFT/B3LYP/6-311++G(d,p) level for all five tautomers of the title molecule. The obtained results show that the calculated vibrational wavenumbers, NMR chemical shifts and UV-vis wavelengths are in a good agreement with experimental data. Copyright © 2016 Elsevier B.V. All rights reserved.

Upgrade of a UV-VIS-NIR imaging spectrometer for the coastal ocean observation: concept, design, fabrication, and test of prototype.

Science.gov (United States)

Yu, Lei

2017-06-26

A novel UV-VIS-NIR imaging spectrometer prototype has been presented for the remote sensing of the coastal ocean by air. The concept is proposed for the needs of the observation. An advanced design has been demonstrated based on the Dyson spectrometer in details. The analysis and tests present excellent optical performances in the spectral broadband, easy and low cost fabrication and alignment, low inherent stray light, and high signal to noise ratio. The research provides an easy method for the coastal ocean observation.

SAXS Combined with UV-vis Spectroscopy and QELS: Accurate Characterization of Silver Sols Synthesized in Polymer Matrices.

Science.gov (United States)

Bulavin, Leonid; Kutsevol, Nataliya; Chumachenko, Vasyl; Soloviov, Dmytro; Kuklin, Alexander; Marynin, Andrii

2016-12-01

The present work demonstrates a validation of small-angle X-ray scattering (SAXS) combining with ultra violet and visible (UV-vis) spectroscopy and quasi-elastic light scattering (QELS) analysis for characterization of silver sols synthesized in polymer matrices. Polymer matrix internal structure and polymer chemical nature actually controlled the sol size characteristics. It was shown that for precise analysis of nanoparticle size distribution these techniques should be used simultaneously. All applied methods were in good agreement for the characterization of size distribution of small particles (less than 60 nm) in the sols. Some deviations of the theoretical curves from the experimental ones were observed. The most probable cause is that nanoparticles were not entirely spherical in form.

Measurement of soluble solids content in watermelon by Vis/NIR diffuse transmittance technique.

Science.gov (United States)

Tian, Hai-qing; Ying, Yi-bin; Lu, Hui-shan; Fu, Xia-ping; Yu, Hai-yan

2007-02-01

Watermelon is a popular fruit in the world with soluble solids content (SSC) being one of the major characteristics used for assessing its quality. This study was aimed at obtaining a method for nondestructive SSC detection of watermelons by means of visible/near infrared (Vis/NIR) diffuse transmittance technique. Vis/NIR transmittance spectra of intact watermelons were acquired using a low-cost commercially available spectrometer operating over the range 350~1000 nm. Spectra data were analyzed by two multivariate calibration techniques: partial least squares (PLS) and principal component regression (PCR) methods. Two experiments were designed for two varieties of watermelons [Qilin (QL), Zaochunhongyu (ZC)], which have different skin thickness range and shape dimensions. The influences of different data preprocessing and spectra treatments were also investigated. Performance of different models was assessed in terms of root mean square errors of calibration (RMSEC), root mean square errors of prediction (RMSEP) and correlation coefficient (r) between the predicted and measured parameter values. Results showed that spectra data preprocessing influenced the performance of the calibration models. The first derivative spectra showed the best results with high correlation coefficient of determination [r=0.918 (QL); r=0.954 (ZC)], low RMSEP [0.65 degrees Brix (QL); 0.58 degrees Brix (ZC)], low RMSEC [0.48 degrees Brix (QL); 0.34 degrees Brix (ZC)] and small difference between the RMSEP and the RMSEC by PLS method. The nondestructive Vis/NIR measurements provided good estimates of SSC index of watermelon, and the predicted values were highly correlated with destructively measured values for SSC. The models based on smoothing spectra (Savitzky-Golay filter smoothing method) did not enhance the performance of calibration models obviously. The results indicated the feasibility of Vis/NIR diffuse transmittance spectral analysis for predicting watermelon SSC in a

Solvent effect in implicit/explicit model on FT-IR, 1H, 13C and 19F NMR, UV-vis and fluorescence spectra, linear, second- and third-nonlinear optical parameters of 2-(trifluoromethyl)benzoic acid: Experimental and computational study

Science.gov (United States)

Avcı, Davut; Altürk, Sümeyye; Tamer, Ömer; Kuşbazoğlu, Mustafa; Atalay, Yusuf

2017-09-01

FT-IR, 1H, 13C and 19F NMR, UV-vis and fluorescence spectra for 2-(trifluoromethyl)benzoic acid (2-TFMBA) were recorded. DFT//B3LYP/6-31++G(d,p) calculations were used to determine the optimized molecular geometry, vibrational frequencies, 1H, 13C and 19F GIAO-NMR chemical shifts of 2-TFMBA. The detailed assignments of vibrational frequencies were carried out on the basis of potential energy distribution (PED) by using VEDA program. TD-DFT/B3LYP/6-31++G(d,p) calculations with the PCM (polarizable continuum model) in ethanol and DMSO solvents based on implicit/explicit model and gas phase in the excited state were employed to investigate UV-vis absorption and fluorescence emission wavelengths. The UV-vis and emission spectra were given in ethanol and DMSO solvents, and the major contributions to the electronic transitions were obtained. In addition, the NLO parameters (β, γ and χ(3)) and frontier molecular orbital energies of 2-TFMBA were calculated by using B3LYP/6-31++G(d,p) level. The NLO parameters of 2-TFMBA were compared with that of para-Nitroaniline (pNA) and urea which are the typical NLO materials. The refractive index (n) is calculated by using the Lorentz-Lorenz equation to observe polarization behavior of 2-TFMBA in DMSO and ethanol solvents. In order to investigate intramolecular and hydrogen bonding interactions, NBO calculations were also performed by the same level. To sum up, considering the well-known biological role, photochemical properties of 2-TFMBA were discussed.

Fuzzy clustering evaluation of the discrimination power of UV-Vis and (±) ESI-MS detection system in individual or coupled RPLC for characterization of Ginkgo Biloba standardized extracts.

Science.gov (United States)

Medvedovici, Andrei; Albu, Florin; Naşcu-Briciu, Rodica Domnica; Sârbu, Costel

2014-02-01

Discrimination power evaluation of UV-Vis and (±) electrospray ionization/mass spectrometric techniques, (ESI-MS) individually considered or coupled as detectors to reversed phase liquid chromatography (RPLC) in the characterization of Ginkgo Biloba standardized extracts, is used in herbal medicines and/or dietary supplements with the help of Fuzzy hierarchical clustering (FHC). Seventeen batches of Ginkgo Biloba commercially available standardized extracts from seven manufacturers were measured during experiments. All extracts were within the criteria of the official monograph dedicated to dried refined and quantified Ginkgo extracts, in the European Pharmacopoeia. UV-Vis and (±) ESI-MS spectra of the bulk standardized extracts in methanol were acquired. Additionally, an RPLC separation based on a simple gradient elution profile was applied to the standardized extracts. Detection was made through monitoring UV absorption at 220 nm wavelength or the total ion current (TIC) produced through (±) ESI-MS analysis. FHC was applied to raw, centered and scaled data sets, for evaluating the discrimination power of the method with respect to the origins of the extracts and to the batch to batch variability. The discrimination power increases with the increase of the intrinsic selectivity of the spectral technique being used: UV-Vis

Radiation degradation of waste waters. Reverse phase-high performance liquid chromatography and multicomponent UV-VIS analysis of gamma-irradiated aqueous solutions of nitrobenzene Pt.1

International Nuclear Information System (INIS)

Kuruc, J.; Sahoo, M.K.; Locaj, J.; Hutta, M.

1994-01-01

Saturated aqueous solutions of nitrobenzene (in water, 0.1M nitric acid and 0.1M potassium hydroxide) were irradiated with 60 Co γ-rays in deaerated condition. Radiolytic products were analyzed using reverse phase-high performance liquid chromatography (RP-HPLC) and multicomponent UV-VIS spectrometry. With the aid of RP-HPLC retention times of the radiolytic products were found to be identical with those of isomeric nitrophenols, aminophenols and dinitrophenols. According to the primary information obtained from RP-HPLC and literature, we have chosen ten standards and eleven wavelengths for multicomponent UV-VIS analysis (linear multiparametric regression analysis) and the concentrations of nitrobenzene, nitrophenols, aminophenols and dinitrophenols in water, HNO 3 and KOH solutions were calculated. G-values (molecules/100 eV) of the radiolytic products and decomposition of nitrobenzene in aqueous solutions G(-nitrobenzene) were calculated from the dependence of their concentrations with dose. Ph has relatively little influence on the decrease of concentration of nitrobenzene, but has strong influence on the product composition. (author) 7 refs.; 5 figs.; 5 tabs

Detection of Outliers and Imputing of Missing Values for Water Quality UV-VIS Absorbance Time Series

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Leonardo Plazas-Nossa

2017-01-01

Full Text Available Context: The UV-Vis absorbance collection using online optical captors for water quality detection may yield outliers and/or missing values. Therefore, data pre-processing is a necessary pre-requisite to monitoring data processing. Thus, the aim of this study is to propose a method that detects and removes outliers as well as fills gaps in time series. Method: Outliers are detected using Winsorising procedure and the application of the Discrete Fourier Transform (DFT and the Inverse of Fast Fourier Transform (IFFT to complete the time series. Together, these tools were used to analyse a case study comprising three sites in Colombia ((i Bogotá D.C. Salitre-WWTP (Waste Water Treatment Plant, influent; (ii Bogotá D.C. Gibraltar Pumping Station (GPS; and, (iii Itagüí, San Fernando-WWTP, influent (Medellín metropolitan area analysed via UV-Vis (Ultraviolet and Visible spectra. Results: Outlier detection with the proposed method obtained promising results when window parameter values are small and self-similar, despite that the three time series exhibited different sizes and behaviours. The DFT allowed to process different length gaps having missing values. To assess the validity of the proposed method, continuous subsets (a section of the absorbance time series without outlier or missing values were removed from the original time series obtaining an average 12% error rate in the three testing time series. Conclusions: The application of the DFT and the IFFT, using the 10% most important harmonics of useful values, can be useful for its later use in different applications, specifically for time series of water quality and quantity in urban sewer systems. One potential application would be the analysis of dry weather interesting to rain events, a feat achieved by detecting values that correspond to unusual behaviour in a time series. Additionally, the result hints at the potential of the method in correcting other hydrologic time series.

Coating of gold nanoparticles for medical application: UV-VIS

Science.gov (United States)

Martínez Espinosa, Juan Carlos; Ramírez, Nayem Amtanus Chequer; Funes Oliva, Luis Enrique; Córdova Fraga, Teodoro; Bernal Alvarado, Jesús; Reyes Pablo, Aldelmo; Núñez, Anita Rosa Elvira

2014-11-01

The use of nanostructured materials has gained strength in recent years in the biomedical area; new applications such as the detection of components in living cells have been used in pharmaceutical area, specifically to study the interaction of various antitumor drugs in living tissues, the detection of genes that are closely related to some type of cancer, as well as the detections of protein biomarkers for diseases also have been studied in various research laboratories around of the world. In this work, we characterize the variation of the absorbance of gold nanoparticles (GNPs) coated with different concentration of Bovine Serum Albumin (BSA) protein. We use GNPS of 60 nm of the trademark-TED PELLA, the BSA protein trademark of Sigma Aldrich and based on that proposed protocol by Chithrani et al., 2009 with purposes to obtain an alternative model to determine the optimal stability of the nanoparticles coated with the protein. The colloidal solutions were prepared with BSA at different concentrations (0.25, 0.5, 0.75 and 1% M/V), and were centrifuged at 15,000 rpm for 90 minutes (centrifuge Model Z383K) and a constant temperature of 25 °C. All the spectra sets were obtained within the range from 400 to 700 nm using an UV-VIS spectrophotometer (Thermo Scientific Model 51118650). The results showed a R2 of 0.99 for an exponential curve correlation between the concentration of BSA, and the absorbance measured. We found at higher concentrations of BSA, there is a decrease in the intensity of the absorption spectra in the plasmon resonance. This preliminary model obtained can be used in the stabilization of gold nanoparticles with different proteins of biomedical interest in future experiments and support for functionalization of GNPs with specific membrane markers.

Cost Effective Process Monitoring using UV-VIS-NIR Spectroscopy

International Nuclear Information System (INIS)

Cipiti, B.; McDaniel, M.; Bryan, S.; Pratt, S.

2015-01-01

UV-VIS-NIR Spectroscopy is a simple and inexpensive measurement technology which has been proposed for process monitoring applications at reprocessing plants. The purpose of this work was to examine if spectroscopy could replace more costly analytical measurements to reduce the safeguards burden to the operator or inspector. Recognizing that the higher measurement uncertainty of spectroscopy makes it unsuited for the accountability tanks, the approach instead was to focus on replacing mass spectrometry for random samples that are taken in a plant. The Interim Inventory Verification and Short Inventory Verification (IIV/SIV) at the Rokkasho Reprocessing Plant utilize random sampling of internal process vessels and laboratory measurement using Isotope Dilution Mass Spectrometry (IDMS) to account for plutonium on a timely basis. These measurements are time-consuming, and the low uncertainty may not always be required. For this work, modelling was used to examine if spectroscopy could be used without adversely affecting the safeguards of the plant. The Separation and Safeguards Performance Model (SSPM), developed at Sandia National Laboratories, was utilized to examine the replacement of IDMS measurements with spectroscopy. Modeling results showed that complete replacement of IDMS with spectroscopy lowered the detection probability for diversion by an unacceptable amount. However, partial replacement (only for samples from vessels with low plutonium content) did not adversely affect the detection probability. This partial replacement covers roughly half of the twenty or so sampling points used for the IIV/SIVA cost-benefit analysis was completed to determine the cost savings that this approach can provide based on lower equipment costs, maintenance, and reduction of analysts' time. This work envisions working with the existing sampling system and performing the spectroscopic measurements in the analytical laboratory, but future work could examine incorporating

Discrimination of whisky brands and counterfeit identification by UV-Vis spectroscopy and multivariate data analysis.

Science.gov (United States)

Martins, Angélica Rocha; Talhavini, Márcio; Vieira, Maurício Leite; Zacca, Jorge Jardim; Braga, Jez Willian Batista

2017-08-15

The discrimination of whisky brands and counterfeit identification were performed by UV-Vis spectroscopy combined with partial least squares for discriminant analysis (PLS-DA). In the proposed method all spectra were obtained with no sample preparation. The discrimination models were built with the employment of seven whisky brands: Red Label, Black Label, White Horse, Chivas Regal (12years), Ballantine's Finest, Old Parr and Natu Nobilis. The method was validated with an independent test set of authentic samples belonging to the seven selected brands and another eleven brands not included in the training samples. Furthermore, seventy-three counterfeit samples were also used to validate the method. Results showed correct classification rates for genuine and false samples over 98.6% and 93.1%, respectively, indicating that the method can be helpful for the forensic analysis of whisky samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

Solid state physics

CERN Document Server

Burns, Gerald

2013-01-01

Solid State Physics, International Edition covers the fundamentals and the advanced concepts of solid state physics. The book is comprised of 18 chapters that tackle a specific aspect of solid state physics. Chapters 1 to 3 discuss the symmetry aspects of crystalline solids, while Chapter 4 covers the application of X-rays in solid state science. Chapter 5 deals with the anisotropic character of crystals. Chapters 6 to 8 talk about the five common types of bonding in solids, while Chapters 9 and 10 cover the free electron theory and band theory. Chapters 11 and 12 discuss the effects of moveme

Optochemical sensing of hydrogen chloride gas using meso-tetramesitylporphyrin deposited glass plate

International Nuclear Information System (INIS)

Kalimuthu, Palanisamy; Abraham John, S.

2008-01-01

Meso-tetramesitylporphyrin (MTMP) deposited glass plate (solid state sensor) was used to sense hydrogen chloride (HCl) gas based on optochemical method. Exposure of the solid state sensor to HCl vapor results in the formation of protonated meso-tetramesitylporphyrin (PMTMP). UV-vis and fluorescence spectral techniques were used to study the protonation of MTMP in dichloromethane-methanol mixture. The optical spectra of MTMP show an intense Soret band at 418 nm with a 14 nm red shift upon protonation by HCl. Ab-initio calculations were carried out to visualize the effect of protonation on planarity and stability of the porphyrin ring. The solid state sensor was characterized by UV-vis spectral technique. The sensor exhibits characteristic Soret and Q bands for the deposited MTMP with slight red shift when compared to MTMP in dichloromethane. The concentration of gaseous HCl was monitored from the changes in the absorbance of Soret band of PMTMP at 452 nm. The detection limit of the solid state sensor towards gaseous HCl was found to be 0.03 ppm. The present solid state sensor was highly stable for several months

Revealing Lattice Expansion of Small-Pore Zeolite Catalysts during the Methanol-to-Olefins Process Using Combined Operando X-ray Diffraction and UV-vis Spectroscopy.

Science.gov (United States)

Goetze, Joris; Yarulina, Irina; Gascon, Jorge; Kapteijn, Freek; Weckhuysen, Bert M

2018-03-02

In small-pore zeolite catalysts, where the size of the pores is limited by eight-ring windows, aromatic hydrocarbon pool molecules that are formed inside the zeolite during the Methanol-to-Olefins (MTO) process cannot exit the pores and are retained inside the catalyst. Hydrocarbon species whose size is comparable to the size of the zeolite cage can cause the zeolite lattice to expand during the MTO process. In this work, the formation of retained hydrocarbon pool species during MTO at a reaction temperature of 400 °C was followed using operando UV-vis spectroscopy. During the same experiment, using operando X-ray Diffraction (XRD), the expansion of the zeolite framework was assessed, and the activity of the catalyst was measured using online gas chromatography (GC). Three different small-pore zeolite frameworks, i.e., CHA, DDR, and LEV, were compared. It was shown using operando XRD that the formation of retained aromatic species causes the zeolite lattice of all three frameworks to expand. Because of the differences in the zeolite framework dimensions, the nature of the retained hydrocarbons as measured by operando UV-vis spectroscopy is different for each of the three zeolite frameworks. Consequently, the magnitude and direction of the zeolite lattice expansion as measured by operando XRD also depends on the specific combination of the hydrocarbon species and the zeolite framework. The catalyst with the CHA framework, i.e., H-SSZ-13, showed the biggest expansion: 0.9% in the direction along the c -axis of the zeolite lattice. For all three zeolite frameworks, based on the combination of operando XRD and operando UV-vis spectroscopy, the hydrocarbon species that are likely to cause the expansion of the zeolite cages are presented; methylated naphthalene and pyrene in CHA, 1-methylnaphthalene and phenalene in DDR, and methylated benzene and naphthalene in LEV. Filling of the zeolite cages and, as a consequence, the zeolite lattice expansion causes the

A Modified Method for Determination of Lumefantrine in Human Plasma by HPLC-UV and Combination of Protein Precipitation and Solid-Phase Extraction: Application to a Pharmacokinetic Study

Directory of Open Access Journals (Sweden)

Liusheng Huang

2010-03-01

Full Text Available An HPLC-UV method was developed and validated for the determination of lumefantrine in human plasma. Lumefantrine and its internal standard halofantrine were extracted from plasma samples using protein precipitation with acetonitrile (0.2% perchloric acid followed by solid-phase extraction with Hypersep C8 cartridges. Chromatographic separation was performed on a Zorbax SB-CN HPLC column (3.0 × 150 mm, 3.5 μm with water/methanol (0.1% TFA as the mobile phases in a gradient elution mode. Detection was performed using UV/vis detector at λ = 335 nm. The method showed to be linear over a range of 50–10,000 ng/mL with acceptable intra- and inter-day precision and accuracy. The mean recoveries were 88.2% for lumefatrine and 84.5% for the I.S. The internal standard halofantrine is readily available from commercial sources. This method was successfully applied to a pharmacokinetic interaction study between a first-line antimalarial combination (artemether—lumefantrine and antiretroviral therapy.

Assessment of repeatability of composition of perfumed waters by high-performance liquid chromatography combined with numerical data analysis based on cluster analysis (HPLC UV/VIS - CA).

Science.gov (United States)

Ruzik, L; Obarski, N; Papierz, A; Mojski, M

2015-06-01

High-performance liquid chromatography (HPLC) with UV/VIS spectrophotometric detection combined with the chemometric method of cluster analysis (CA) was used for the assessment of repeatability of composition of nine types of perfumed waters. In addition, the chromatographic method of separating components of the perfume waters under analysis was subjected to an optimization procedure. The chromatograms thus obtained were used as sources of data for the chemometric method of cluster analysis (CA). The result was a classification of a set comprising 39 perfumed water samples with a similar composition at a specified level of probability (level of agglomeration). A comparison of the classification with the manufacturer's declarations reveals a good degree of consistency and demonstrates similarity between samples in different classes. A combination of the chromatographic method with cluster analysis (HPLC UV/VIS - CA) makes it possible to quickly assess the repeatability of composition of perfumed waters at selected levels of probability. © 2014 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

A combined Surface Enhanced Raman Spectroscopy (SERS)/UV-vis approach for the investigation of dye content in commercial felt tip pens inks.

Science.gov (United States)

Saviello, Daniela; Trabace, Maddalena; Alyami, Abeer; Mirabile, Antonio; Giorgi, Rodorico; Baglioni, Piero; Iacopino, Daniela

2018-05-01

The development of protocols for the protection of the large patrimony of works of art created by felt tip pen media since the 1950's requires detailed knowledge of the main dyes constituting commercial ink mixtures. In this work Surface Enhanced Raman Scattering (SERS) and UV-vis spectroscopy were used for the first time for the systematic identification of dye composition in commercial felt tip pens. A large selection of pens comprising six colors of five different brands was analyzed. Intense SERS spectra were obtained for all colors, allowing identification of main dye constituents. Poinceau 4R and Eosin dyes were found to be the main constituents of red and pink colors; Rhodamine and Tartrazine were found in orange and yellow colors; Erioglaucine was found in green and blue colors. UV-vis analysis of the same inks was used to support SERS findings but also to unequivocally assign some uncertain dye identifications, especially for yellow and orange colors. The spectral data of all felt tip pens collected through this work were assembled in a database format. The data obtained through this systematic investigation constitute the basis for the assembly of larger reference databases that ultimately will support the development of conservation protocols for the long term preservation of modern art collections. Copyright © 2018 Elsevier B.V. All rights reserved.

Investigation on intermolecular interaction between berberine and β-cyclodextrin by 2D UV-Vis asynchronous spectra.

Science.gov (United States)

He, Anqi; Kang, Xiaoyan; Xu, Yizhuang; Noda, Isao; Ozaki, Yukihiro; Wu, Jinguang

2017-10-05

The interaction between berberine chloride and β-cyclodextrin (β-CyD) is investigated via 2D asynchronous UV-Vis spectrum. The occurrence of cross peaks around (420nm, 420nm) in 2D asynchronous spectrum reveals that specific intermolecular interaction indeed exists between berberine chloride and β-CyD. In spite of the difficulty caused by overlapping of cross peaks, we manage to confirm that the 420nm band of berberine undergoes a red-shift, and its bandwidth decreases under the interaction with β-CyD. The red-shift of the 420nm band that can be assigned to n-π* transition indicates the environment of berberine becomes more hydrophobic. The above spectral behavior is helpful in understanding why the solubility of berberine is enhanced by β-CyD. Copyright © 2017. Published by Elsevier B.V.

From pirazoloquinolines to annulated azulene dyes: UV-VIS spectroscopy and quantum chemical study

International Nuclear Information System (INIS)

Gasiorski, P.; Danel, K.S.; Matusiewicz, M.; Uchacz, T.; Kityk, A.V.

2010-01-01

Paper reports UV-Vis absorption and photoluminescence spectra of 6-R derivatives (R=CH 3 , O-CH 3 , C(C 6 H 5 ) 3 , C 6 H 5 -N-C 10 H 7 ) of 4-(2-chlorophenyl)-1,3-diphenyl-1H-pyrazolo[3,4-b]quinoline, belonging to pyrazoloquinoline (PQ) family, likewise its regioisomeric products 10-R derivatives of 6-phenyl-6H-5,6,7-triazadibenzo[f,h]naphtho[3,2,1-cd]azulene representing cyclized seven-membered annulated azulene (AA) dyes. Cyclization of PQs into AAs is accompanied by a significant red shift of the first optical absorption band. This finding agrees with the results of quantum-chemical calculations performed by means of the semiempirical method PM3. As the solvent polarity rises all the dyes exhibit a blue shift of the first absorption band and a red shift of the fluorescence band. Such opposite trends in solvatochromic behavior have been reproduced within the semiempirical calculations in combination with the Lippert-Mataga dielectric polarization model. Depending on solvent polarity AA dyes emit light in the green, green-yellow or orange range of the visible spectrum what may be of interest for potential luminescent or electroluminescent applications.

Effect of the nickel precursor on the impregnation and drying of γ-Al2O3 catalyst bodies: a UV-vis and IR micro-spectroscopic study

NARCIS (Netherlands)

Espinosa Alonso, L.; de Jong, K.P.; Weckhuysen, B.M.

2008-01-01

The elemental preparation steps of impregnation and drying of Ni/g-Al2O3 catalyst bodies have been studied by combining UV-vis and IR microspectroscopy. The influence of the number of chelating ligands in [Ni(en)x(H2O)6-2x]2+ precursor complexes (with en ) ethylenediamine and x ) 0-3) has been

UV/Vis spectroscopy of C60 embedded in water ice

DEFF Research Database (Denmark)

Cuylle, Steven; Linnartz, Harold; Thrower, John

2012-01-01

Electronic solid state spectra are recorded for C60 embedded in 40 K water ice using broad band direct absorption spectroscopy, and assigned with reference to existing matrix data. The results are interesting in view of the recent gas phase detection of fullerenes in the interstellar medium...

Evaluation of electrochemical, UV/VIS and Raman spectroelectrochemical detection of Naratriptan with screen-printed electrodes.

Science.gov (United States)

Hernández, Carla Navarro; Martín-Yerga, Daniel; González-García, María Begoña; Hernández-Santos, David; Fanjul-Bolado, Pablo

2018-02-01

Naratriptan, active pharmaceutical ingredient with antimigraine activity was electrochemically detected in untreated screen-printed carbon electrodes (SPCEs). Cyclic voltammetry and differential pulse voltammetry were used to carry out quantitative analysis of this molecule (in a Britton-Robinson buffer solution at pH 3.0) through its irreversible oxidation (diffusion controlled) at a potential of +0.75V (vs. Ag pseudoreference electrode). Naratriptan oxidation product is an indole based dimer with a yellowish colour (maximum absorption at 320nm) so UV-VIS spectroelectrochemistry technique was used for the very first time as an in situ characterization and quantification technique for this molecule. A reflection configuration approach allowed its measurement over the untreated carbon based electrode. Finally, time resolved Raman Spectroelectrochemistry is used as a powerful technique to carry out qualitative and quantitative analysis of Naratriptan. Electrochemically treated silver screen-printed electrodes are shown as easy to use and cost-effective SERS substrates for the analysis of Naratriptan. Copyright © 2017 Elsevier B.V. All rights reserved.

Solid State Pathways towards Molecular Complexity in Space

Science.gov (United States)

Linnartz, Harold; Bossa, Jean-Baptiste; Bouwman, Jordy; Cuppen, Herma M.; Cuylle, Steven H.; van Dishoeck, Ewine F.; Fayolle, Edith C.; Fedoseev, Gleb; Fuchs, Guido W.; Ioppolo, Sergio; Isokoski, Karoliina; Lamberts, Thanja; Öberg, Karin I.; Romanzin, Claire; Tenenbaum, Emily; Zhen, Junfeng

2011-12-01

It has been a long standing problem in astrochemistry to explain how molecules can form in a highly dilute environment such as the interstellar medium. In the last decennium more and more evidence has been found that the observed mix of small and complex, stable and highly transient species in space is the cumulative result of gas phase and solid state reactions as well as gas-grain interactions. Solid state reactions on icy dust grains are specifically found to play an important role in the formation of the more complex ``organic'' compounds. In order to investigate the underlying physical and chemical processes detailed laboratory based experiments are needed that simulate surface reactions triggered by processes as different as thermal heating, photon (UV) irradiation and particle (atom, cosmic ray, electron) bombardment of interstellar ice analogues. Here, some of the latest research performed in the Sackler Laboratory for Astrophysics in Leiden, the Netherlands is reviewed. The focus is on hydrogenation, i.e., H-atom addition reactions and vacuum ultraviolet irradiation of interstellar ice analogues at astronomically relevant temperatures. It is shown that solid state processes are crucial in the chemical evolution of the interstellar medium, providing pathways towards molecular complexity in space.

Study on molecular structure, spectroscopic properties (FTIR and UV-Vis), NBO, QTAIM, HOMO-LUMO energies and docking studies of 5-fluorouracil, a substance used to treat cancer

Science.gov (United States)

Almeida, Michell O.; Barros, Daiane A. S.; Araujo, Sheila C.; Faria, Sergio H. D. M.; Maltarollo, Vinicius G.; Honorio, Kathia M.

2017-09-01

Cancer cells can expand to other parts of body through blood system and nodes from a mechanism known as metastasis. Due to the large annual growth of cancer cases, various biological targets have been studied and related to this disorder. A very interesting target related to cancer is human epidermal growth factor receptor 2 (HER2). In this study, we analyzed the main intermolecular interactions between a drug used in the cancer treatment (5-fluorouracil) and HER2. Molecular modeling methods were also employed to assess the molecular structure, spectroscopic properties (FTIR and UV-Vis), NBO, QTAIM and HOMO-LUMO energies of 5-FU. From the docking simulations it was possible to analyze the interactions that occur between some residues in the binding site of HER2 and 5-FU. To validate the choice of basis set that was used in the NBO and QTAIM analyses, theoretical calculations were performed to obtain FT-IR and UV/Vis spectra, and the theoretical results are consistent with the experimental data, showing that the basis set chosen is suitable. For the maximum λ from the theoretical calculation (254.89 nm) of UV/Vis, the electronic transition from HOMO to LUMO occurs at 4.89 eV. From NBO analyses, we observed interactions between Asp863 and 5-FU, i.e. the orbitals with high transfer of electrons are LP O15 (donor NBO) and BD* (π) N1-H10 (acceptor NBO), being that the value of this interaction is 7.72 kcal/mol. Results from QTAIM indicate one main intermolecular H bond, which is necessary to stabilize the complex formed between the ligands and the biological target. Therefore, this study allowed a careful evaluation on the main structural, spectroscopic and electronic properties involved in the interaction between 5-FU and HER2, an important biological complex related to the cancer treatment.

Rapid ultrasound-assisted magnetic microextraction of gallic acid from urine, plasma and water samples by HKUST-1-MOF-Fe3O4-GA-MIP-NPs: UV-vis detection and optimization study.

Science.gov (United States)

Asfaram, Arash; Ghaedi, Mehrorang; Dashtian, Kheibar

2017-01-01

Magnetite (Fe 3 O 4 nanoparticles (NPs)) HKUST-1 metal organic framework (MOF) composite as a support was used for surface imprinting of gallic acid imprinted polymer (HKUST-1-MOF-Fe 3 O 4 -GA-MIP) using vinyltrimethoxysilane (VTMOS) as the cross-linker. Subsequently, HKUST-1-MOF-Fe 3 O 4 -NPs-GA-MIP characterized by FT-IR, XRD and FE-SEM analysis and applied for fast and selective and sensitive ultrasound assisted dispersive magnetic solid phase microextraction of gallic acid (GA) by UV-Vis (UA-DMSPME-UV-Vis) detection method. Plackett-Burman design (PBD) and central composite design (CCD) according to desirability function (DF) indicate the significant variables among the extraction factors vortex (mixing) time (min), sonication time (min), temperature (°C), eluent volume (L), pH and HKUST-1-MOF-Fe 3 O 4 -NPs-GA-MIP mass (mg) and their contribution on the response. Optimum conditions and values correspond to pH, HKUST-1-MOF-Fe 3 O 4 -NPs-GA-MIP mass, sonication time and the eluent volume were set as follow 3.0, 1.6mg, 4.0min and 180μL, respectively. The average recovery (ER%) of GA was 98.13% with desirability of 0.997, while the present method has best operational performance like wide linear range 8-6000ngmL -1 with a Limit of detection (LOD) of 1.377ngmL -1 , limit of quantification (LOQ) 4.591ngmL -1 and precision (<3.50% RSD). The recovery of GA in urine, human plasma and water samples within the range of 92.3-100.6% that strongly support high applicability of present method for real samples analysis, which candidate this method as promise for further application. Copyright © 2016. Published by Elsevier B.V.

Formation and proof of stable bi-, tri- and tetraradical polyanions during the electrochemical reduction of cone-polynitrocalix[4]arenes. An ESR-UV-vis spectroelectrochemical study

International Nuclear Information System (INIS)

Liška, Alan; Rosenkranz, Marco; Klíma, Jiří; Dunsch, Lothar; Lhoták, Pavel; Ludvík, Jiří

2014-01-01

Graphical abstract: - Abstract: The first intermediates of electrochemical reduction of nitro compounds in nonaqueous DMF are stable radical anions. In the series of mono-, di-, tri- and tetranitro calix[4]arenes each nitro group represents a reduction center, therefore the question about the spin state of intermediary anions arises. In this communication, the voltammetric and coulometric investigation of these compounds is performed together with the spectral measurements (ESR and UV-vis). The in-situ spectroelectrochemical approach proved that during reduction, in all polynitro radicalic intermediates the electrons remain unpaired and thus relatively stable mono-, di-, tri- and tetraradical mono-, di-, tri- and tetraanions, respectively, can be electrochemically generated in aprotic DMF from polynitrocalix[4]arenes. This finding confirms that the nitrophenyl units in polynitrocalix[4]arenes are completely independent and no mutual electronic communication takes place among them

Interrelating meteorite and asteroid spectra at UV-Vis-NIR wavelengths using novel multiple-scattering methods

Science.gov (United States)

Martikainen, Julia; Penttilä, Antti; Gritsevich, Maria; Muinonen, Karri

2017-10-01

Asteroids have remained mostly the same for the past 4.5 billion years, and provide us information on the origin, evolution and current state of the Solar System. Asteroids and meteorites can be linked by matching their respective reflectance spectra. This is difficult, because spectral features depend strongly on the surface properties, and meteorite surfaces are free of regolith dust present in asteroids. Furthermore, asteroid surfaces experience space weathering which affects their spectral features.We present a novel simulation framework for assessing the spectral properties of meteorites and asteroids and matching their reflectance spectra. The simulations are carried out by utilizing a light-scattering code that takes inhomogeneous waves into account and simulates light scattering by Gaussian-random-sphere particles large compared to the wavelength of the incident light. The code uses incoherent input and computes phase matrices by utilizing incoherent scattering matrices. Reflectance spectra are modeled by combining olivine, pyroxene, and iron, the most common materials that dominate the spectral features of asteroids and meteorites. Space weathering is taken into account by adding nanoiron into the modeled asteroid spectrum. The complex refractive indices needed for the simulations are obtained from existing databases, or derived using an optimization that utilizes our ray-optics code and the measured spectrum of the material.We demonstrate our approach by applying it to the reflectance spectrum of (4) Vesta and the reflectance spectrum of the Johnstown meteorite measured with the University of Helsinki integrating-sphere UV-Vis-NIR spectrometer.Acknowledgments. The research is funded by the ERC Advanced Grant No. 320773 (SAEMPL).

Structural Identification of 19 Purified Isomers of the OPV Acceptor Material bisPCBM by 13C NMR and UV-Vis Absorption Spectroscopy and High-Performance Liquid Chromatography.

Science.gov (United States)

Liu, Tong; Abrahams, Isaac; Dennis, T John S

2018-04-26

The molecular structures of 19 purified isomers of bis-phenyl-C 62 -butyric acid methyl ester were identified by a combination of 13 C NMR and UV-vis absorption spectroscopies and high-performance liquid chromatography (HPLC) retention time analysis. All 19 isomers are dicyclopropafullerenes (none are homofullerenes). There were seven isomers with C 1 molecular point-group symmetry, four with C s , six with C 2 , one with C 2 v , and one with C 2 h symmetry. The C 2 h , C 2 v , and all five nonequatorial C 1 isomers were unambiguously assigned to their respective HPLC fractions. For the other 12 isomers, the 13 C NMR and UV-vis spectra placed them in six groups of two same-symmetry isomers. On the basis of the widely spaced HPLC retention times of the two isomers within each of these six groups, and the empirical inverse correlation between retention time and addend spacing, each isomer was assigned to its corresponding HPLC fraction. In addition, the missing trans-1 isomer was found, purified, and characterized.

Assessing Pearl Quality Using Reflectance UV-Vis Spectroscopy: Does the Same Donor Produce Consistent Pearl Quality?

Directory of Open Access Journals (Sweden)

Paul C. Southgate

2010-09-01

Full Text Available Two groups of commercial quality (“acceptable” pearls produced using two donors, and a group of “acceptable” pearls from other donors were analyzed using reflectance UV-Vis spectrophotometry. Three pearls with different colors produced by the same donor showed different absorption spectra. Cream and gold colored pearls showed a wide absorption from 320 to about 460 nm, while there was just slight reflectance around 400 nm by the white pearl with a pink overtone. Cream and gold pearls reached a reflectance peak at 560 to 590 nm, while the white pearl with pink overtone showed slightly wider absorption in this region. Both cream and gold pearls showed an absorption peak after the reflectance peak, at about 700 nm for the cream pearl and 750 nm for the gold pearl. Two other pearls produced by the same donor (white with cream overtone and cream with various overtones showed similar spectra, which differed in their intensity. One of these pearls had very high lustre and its spectrum showed a much higher percentage reflectance than the second pearl with inferior lustre. This result may indicate that reflectance is a useful quantitative indicator of pearl lustre. The spectra of two white pearls resulting from different donors with the same color nacre (silver showed a reflectance at 260 nm, followed by absorption at 280 nm and another reflectance peak at 340 nm. After this peak the spectra for these pearls remained flat until a slight absorption peak around 700 nm. Throughout the visible region, all white pearls used in this study showed similar reflectance spectra although there were differences in reflectance intensity. Unlike the spectral results from white pearls, the results from yellow and gold pearls varied according to color saturation of the pearl. The results of this study show that similarities between absorption and reflectance spectra of cultured pearls resulting from the same saibo donor are negligible and could not be detected

Synthesis and characterization of CeO2-TiO2-Pr6O11 solid solutions for environmentally benign nontoxic red pigments

International Nuclear Information System (INIS)

George, Giable; Rao, Padala Prabhakar; Reddy, Mundlapudi Lakshmipathi

2006-01-01

New inorganic pigments Ce 1-(x+y) Ti x Pr y O 2 (x ranges from 0.05 to 0.195 and y ranges from 0.005 to 0.15) based on CeO 2 -TiO 2 -Pr 6 O 11 solid solutions have been synthesized by solid-state route with a goal of preparing environmentally secure red colorants. Characterizations using XRD, UV-vis spectroscopy and CIE 1976 color coordinates assessment reveals the formation of pigments displaying colors ranging from brick red to dark brown. The coloring mechanism is based on the introduction of additional electronic level of energy in the cerianite forbidden band from the unpaired 4f electron of lanthanide ion. (author)

Quantum chemical investigations on the molecular structure, FTIR, UV-Vis and HOMO-LUMO analysis of 15-16-epoxy-7b, 9a dihydroxylabdane 13(16), 14-dien-6-one

Science.gov (United States)

Uppal, Anshul; Pathania, Kamni; Khajuria, Yugal

2018-05-01

The structural, spectroscopic (Fourier Transform Infrared (FT-IR), Ultra-Violet Visible (UV-VIS)) and thermodynamic properties of 15, 16-epoxy-7b, 9a dihydroxylabdane-13(16), 14-dien-6-one were studied by using both experimental techniques and theoretical methods. The FTIR spectrum of the title compound was recorded in the spectral range 4000-400 cm-1. The UV-VIS spectrum was measured in the spectral range 190-800 nm. The quantum chemistry calculations have been performed to compute optimized geometry, molecular parameters, vibrational frequencies along with intensities using Hartree Fock (HF) theory and Density Functional Theory (DFT) with 6-31G basis set. The calculated HOMO-LUMO energies show that the charge transfer occurs within the molecule. The temperature dependence of the thermodynamic properties like heat capacity, entropy and enthalpy of the optimized structure were obtained. Finally, a comparison between the experimental data and the calculated results presented a good agreement.

High energy, high average power solid state green or UV laser

Science.gov (United States)

Hackel, Lloyd A.; Norton, Mary; Dane, C. Brent

2004-03-02

A system for producing a green or UV output beam for illuminating a large area with relatively high beam fluence. A Nd:glass laser produces a near-infrared output by means of an oscillator that generates a high quality but low power output and then multi-pass through and amplification in a zig-zag slab amplifier and wavefront correction in a phase conjugator at the midway point of the multi-pass amplification. The green or UV output is generated by means of conversion crystals that follow final propagation through the zig-zag slab amplifier.

Focal plane instrument for the Solar UV-Vis-IR Telescope aboard SOLAR-C

Science.gov (United States)

Katsukawa, Yukio; Suematsu, Yoshinori; Shimizu, Toshifumi; Ichimoto, Kiyoshi; Takeyama, Norihide

2011-10-01

It is presented the conceptual design of a focal plane instrument for the Solar UV-Vis-IR Telescope (SUVIT) aboard the next Japanese solar mission SOLAR-C. A primary purpose of the telescope is to achieve precise as well as high resolution spectroscopic and polarimetric measurements of the solar chromosphere with a big aperture of 1.5 m, which is expected to make a significant progress in understanding basic MHD processes in the solar atmosphere. The focal plane instrument consists of two packages: A filtergraph package is to get not only monochromatic images but also Dopplergrams and magnetograms using a tunable narrow-band filter and interference filters. A spectrograph package is to perform accurate spectro-polarimetric observations for measuring chromospheric magnetic fields, and is employing a Littrow-type spectrograph. The most challenging aspect in the instrument design is wide wavelength coverage from 280 nm to 1.1 μm to observe multiple chromospheric lines, which is to be realized with a lens unit including fluoride glasses. A high-speed camera for correlation tracking of granular motion is also implemented in one of the packages for an image stabilization system, which is essential to achieve high spatial resolution and high polarimetric accuracy.

Characterization of the Pore Filling of Solid State Dye Sensitized Solar Cells with Photoinduced Absorption Spectroscopy

Directory of Open Access Journals (Sweden)

Carol Olson

2011-01-01

Full Text Available Near steady-state photoinduced absorption (PIA and UV-Vis absorption spectroscopy are used to characterize the pore filling of spiro-MeOTAD (2,2′,7,7′-tetrakis-(N,N-di-p-methoxyphenylamine9,9′-spirobifluorene into the nanoparticulate TiO2 electrode of a solid-state dye-sensitized solar cell (ssDSC. The volumetric ratio of filled to unfilled pore volumes, as well as the optical signature of interacting chemical species, that is, the hole-transfer yield (HTY, are investigated. PIA spectroscopy is used to measure the HTY, relative to the amount of spiro-MeOTAD present, without needing to determine the extinction coefficients of the dye and spiro-MeOTAD cation species. The Beer-Lambert law is used to relate the relative PIA signal to the penetration length of the hole-conductor in the TiO2 film. For the sample thickness range of 1.4–5 μm investigated here, the optimum characteristic penetration length is determined to be 3.1+0.46 μm, which is compared to 1.4 μm for the 200 mg mL−1 concentration of spiro-MeOTAD conventionally used. Therefore, doubling the effective penetration of spiro-MeOTAD is necessary to functionalize all the dye molecules in a ssDSC.

Ultrafast infrared and UV-vis studies of the photochemistry of methoxycarbonylphenyl azides in solution.

Science.gov (United States)

Xue, Jiadan; Luk, Hoi Ling; Eswaran, S V; Hadad, Christopher M; Platz, Matthew S

2012-06-07

The photochemistry of 4-methoxycarbonylphenyl azide (2a), 2-methoxycarbonylphenyl azide (3a), and 2-methoxy-6-methoxycarbonylphenyl azide (4a) were studied by ultrafast time-resolved infrared (IR) and UV-vis spectroscopies in solution. Singlet nitrenes and ketenimines were observed and characterized for all three azides. Isoxazole species 3g and 4g are generated after photolysis of 3a and 4a, respectively, in acetonitrile. Triplet nitrene 4e formation correlated with the decay of singlet nitrene 4b. The presence of water does not change the chemistry or kinetics of singlet nitrenes 2b and 3b, but leads to protonation of 4b to produce nitrenium ion 4f. Singlet nitrenes 2b and 3b have lifetimes of 2 ns and 400 ps, respectively, in solution at ambient temperature. The singlet nitrene 4b in acetonitrile has a lifetime of about 800 ps, and reacts with water with a rate constant of 1.9 × 10(8) L·mol(-1)·s(-1) at room temperature. These results indicate that a methoxycarbonyl group at either the para or ortho positions has little influence on the ISC rate, but that the presence of a 2-methoxy group dramatically accelerates the ISC rate relative to the unsubstituted phenylnitrene. An ortho-methoxy group highly stabilizes the corresponding nitrenium ion and favors its formation in aqueous solvents. This substituent has little influence on the ring-expansion rate. These results are consistent with theoretical calculations for the various intermediates and their transition states. Cyclization from the nitrene to the azirine intermediate is favored to proceed toward the electron-deficient ester group; however, the higher energy barrier is the ring-opening process, that is, azirine to ketenimine formation, rendering the formation of the ester-ketenimine (4d') to be less favorable than the isomeric MeO-ketenimine (4d).

Phosphonate self-assembled monolayers as organic linkers in solid-state quantum dot sensetized solar cells

KAUST Repository

Ardalan, Pendar; Brennan, Thomas P.; Bakke, Jonathan R.; Bent, Stacey F.

2010-01-01

We have employed X-ray photoelectron spectroscopy (XPS), ultraviolet-visible (UV-vis) spectroscopy, infrared (IR) spectroscopy, water contact angle (WCA) measurements, ellipsometry, and electrical measurements to study the effects of self

Synthesis and Study of Optical Properties of Graphene/TiO2 Composites Using UV-VIS Spectroscopy

Science.gov (United States)

Rathod, P. B.; Waghuley, S. A.

2016-09-01

Graphene and TiO2 were synthesized using electrochemical exfoliation and co-precipitation methods, respectively. An ex situ approach was adopted for the graphene/TiO2 composites. The conformation of graphene in the TiO2 samples was examined through X-ray diffraction. Optical properties of the as-synthesised composites such as optical absorption, extinction coefficient, refractive index, real dielectric constant, imaginary dielectric constant, dissipation factor, and optical conductivity were measured using UV-Vis spectroscopy. The varying concentration of graphene in TiO2 affects the optical properties which appear different for 10 wt.% as compared to 5 wt.% graphene/ TiO2 composite. The composites exhibit an absorption peak at 300 nm with a decrease in band gap for 10 wt.% as compared to 5 wt.% graphene/TiO2 composite. The maximum optical conductivity for the graphene/TiO2 composite of 10 wt.% was found to be 1.86·10-2 Ω-1·m-1 at 300 nm.

Study of Interaction between Cadmium and Bovine Serum Albumin with UV-Vis Spectrocopy Approach

Science.gov (United States)

Suhartono, E.; Thalib, I.; Aflanie, I.; Noor, Z.; Idroes, R.

2018-05-01

This study aims to explain the interaction of cadmium (Cd) with serum albumin through visible light (UV-Vis) spectroscopy approach. This study is an in vitro experimental study using Cd with several concentrations and Bovine Serum Albumin (BSA). Each solution was then incubated for 10 min at 37°C, and measured the absorbance at 220-300 nm. The absorbance data is then presented in graphical form. From the graph, a linear equation will appear to calculate the value of metal binding constants (K) to proteins. Also, in this present study we analsyed the ratio between A220 and A220 to identify changes in the protein region especially tyrosine and peptide bonds. The results show that the addition of Cd in different concentrations could increase the absorbance with a constant value (K) = 1.634. Based on the result, it seems the addition of Cd in different concentrations will lead the reaction to form BSA-Cd. Also, the result shows that the ration of A220/A280 were decreased with the increasing of Cd concentration. In conclusion, the addition of Cd could interact and changes the protein structure in BSA.

Solid State Division

International Nuclear Information System (INIS)

Green, P.H.; Watson, D.M.

1989-08-01

This report contains brief discussions on work done in the Solid State Division of Oak Ridge National Laboratory. The topics covered are: Theoretical Solid State Physics; Neutron scattering; Physical properties of materials; The synthesis and characterization of materials; Ion beam and laser processing; and Structure of solids and surfaces

Solid State Division

Energy Technology Data Exchange (ETDEWEB)

Green, P.H.; Watson, D.M. (eds.)

1989-08-01

This report contains brief discussions on work done in the Solid State Division of Oak Ridge National Laboratory. The topics covered are: Theoretical Solid State Physics; Neutron scattering; Physical properties of materials; The synthesis and characterization of materials; Ion beam and laser processing; and Structure of solids and surfaces. (LSP)

Phase separation of in situ forming poly (lactide-co-glycolide acid) implants investigated using a hydrogel-based subcutaneous tissue surrogate and UV-vis imaging.

Science.gov (United States)

Sun, Yu; Jensen, Henrik; Petersen, Nickolaj J; Larsen, Susan W; Østergaard, Jesper

2017-10-25

Phase separation of in situ forming poly (lactide-co-glycolide acid) (PLGA) implants with agarose hydrogels as the provider of nonsolvent (water) mimicking subcutaneous tissue was investigated using a novel UV-vis imaging-based analytical platform. In situ forming implants of PLGA-1-methyl-2-pyrrolidinone and PLGA-triacetin representing fast and slow phase separating systems, respectively, were evaluated using this platform. Upon contact with the agarose hydrogel, the phase separation of the systems was followed by the study of changes in light transmission and absorbance as a function of time and position. For the PLGA-1-methyl-2-pyrrolidinone system, the rate of spatial phase separation was determined and found to decrease with increasing the PLGA concentration from 20% to 40% (w/w). Hydrogels with different agarose concentrations (1% and 10% (w/v)) were prepared for providing the nonsolvent, water, to the in situ forming PLGA implants simulating the injection site environment. The resulting implant morphology depended on the stiffness of hydrogel matrix, indicating that the matrix in which implants are formed is of importance. Overall, the work showed that the UV-vis imaging-based platform with an agarose hydrogel mimicking the subcutaneous tissue holds potential in providing bio-relevant and mechanistic information on the phase separation processes of in situ forming implants. Copyright © 2017 Elsevier B.V. All rights reserved.

Hydrocarbons in interstellar ice analogues : UV-vis spectroscopy and VUV photochemistry

NARCIS (Netherlands)

Cuylle, Steven Hendrik

2015-01-01

This thesis treats the chemical behaviour of carbonaceous molecules in water-dominated interstellar ices. VUV photons are considered as the chemical trigger to induce solid state chemistry as it is omnipresent. Lyman- radiation occurs even in dense molecular clouds as a result of cosmic ray

Self-assembled organic monolayers on gold nanoparticles: A study by sum-frequency generation combined with UV-vis spectroscopy

International Nuclear Information System (INIS)

Humbert, C.; Busson, B.; Abid, J.-P.; Six, C.; Girault, H.H.; Tadjeddine, A.

2005-01-01

We use sum-frequency generation spectroscopy (SFG) in the infrared 2800-3000 cm -1 spectral range and UV-vis spectroscopy (transmission) in the 450-650 nm spectral range in order to characterize vibrational and electronic properties of various interfaces composed of organic monolayers adsorbed on gold nanoparticles (AuNPs) with 19 nm average diameter. SFG signal is observed for AuNPs films deposited on glass substrates using the following silane intermediates: 3-(aminopropyl) triethoxysilane and 3-(mercaptopropyl) trimethoxysilane. The density of AuNPs and their aggregates are measured with a scanning electron microscope. For the samples showing a strong well-defined surface plasmon resonance (SPR), we also observe an enhancement of their non-linear optical properties. Furthermore, the SFG measurements show that 1-dodecanethiol films are rather well ordered on specific AuNPs substrates. In this way, the presence of the SFG signal, which comes from both the bulk electronic s-d interband transition and the vibrational states of the adsorbed molecules, depends on a SPR process. This phenomenon is evidenced on the AuNPs by the incident visible beam located at 532 nm, i.e. near the SPR energy maximum of these interfaces. These results open the door to experiments involving macromolecular and biological materials networks deposited on ultrathin metal electrodes in a controlled electrochemical environment

Self-assembled organic monolayers on gold nanoparticles: A study by sum-frequency generation combined with UV-vis spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Humbert, C. [LURE, CNRS-UMR 130, Centre Universitaire Paris-Sud, Ba-hat t. 209D, B.P. 34, 91898 Orsay Cedex (France) and Laboratoire de Spectroscopie Moleculaire de Surface, University of Namur, 61 Rue de Bruxelles, B-5000 Namur (Belgium)]. E-mail: christophe.humbert@fundp.ac.be; Busson, B. [LURE, CNRS-UMR 130, Centre Universitaire Paris-Sud, Ba-hat t. 209D, B.P. 34, 91898 Orsay Cedex (France); Abid, J.-P. [Ecole Polytechnique Federale de Lausanne, Laboratoire d' Electrochimie Physique et Analytique, CH-1015 Lausanne (Switzerland); Six, C. [LURE, CNRS-UMR 130, Centre Universitaire Paris-Sud, Ba-hat t. 209D, B.P. 34, 91898 Orsay Cedex (France); Girault, H.H. [Ecole Polytechnique Federale de Lausanne, Laboratoire d' Electrochimie Physique et Analytique, CH-1015 Lausanne (Switzerland); Tadjeddine, A. [LURE, CNRS-UMR 130, Centre Universitaire Paris-Sud, Ba-hat t. 209D, B.P. 34, 91898 Orsay Cedex (France)

2005-05-20

We use sum-frequency generation spectroscopy (SFG) in the infrared 2800-3000 cm{sup -1} spectral range and UV-vis spectroscopy (transmission) in the 450-650 nm spectral range in order to characterize vibrational and electronic properties of various interfaces composed of organic monolayers adsorbed on gold nanoparticles (AuNPs) with 19 nm average diameter. SFG signal is observed for AuNPs films deposited on glass substrates using the following silane intermediates: 3-(aminopropyl) triethoxysilane and 3-(mercaptopropyl) trimethoxysilane. The density of AuNPs and their aggregates are measured with a scanning electron microscope. For the samples showing a strong well-defined surface plasmon resonance (SPR), we also observe an enhancement of their non-linear optical properties. Furthermore, the SFG measurements show that 1-dodecanethiol films are rather well ordered on specific AuNPs substrates. In this way, the presence of the SFG signal, which comes from both the bulk electronic s-d interband transition and the vibrational states of the adsorbed molecules, depends on a SPR process. This phenomenon is evidenced on the AuNPs by the incident visible beam located at 532 nm, i.e. near the SPR energy maximum of these interfaces. These results open the door to experiments involving macromolecular and biological materials networks deposited on ultrathin metal electrodes in a controlled electrochemical environment.

Submersible UV-Vis spectroscopy for quantifying streamwater organic carbon dynamics: implementation and challenges before and after forest harvest in a headwater stream.

Science.gov (United States)

Jollymore, Ashlee; Johnson, Mark S; Hawthorne, Iain

2012-01-01

Organic material, including total and dissolved organic carbon (DOC), is ubiquitous within aquatic ecosystems, playing a variety of important and diverse biogeochemical and ecological roles. Determining how land-use changes affect DOC concentrations and bioavailability within aquatic ecosystems is an important means of evaluating the effects on ecological productivity and biogeochemical cycling. This paper presents a methodology case study looking at the deployment of a submersible UV-Vis absorbance spectrophotometer (UV-Vis spectro::lyzer model, s::can, Vienna, Austria) to determine stream organic carbon dynamics within a headwater catchment located near Campbell River (British Columbia, Canada). Field-based absorbance measurements of DOC were made before and after forest harvest, highlighting the advantages of high temporal resolution compared to traditional grab sampling and laboratory measurements. Details of remote deployment are described. High-frequency DOC data is explored by resampling the 30 min time series with a range of resampling time intervals (from daily to weekly time steps). DOC export was calculated for three months from the post-harvest data and resampled time series, showing that sampling frequency has a profound effect on total DOC export. DOC exports derived from weekly measurements were found to underestimate export by as much as 30% compared to DOC export calculated from high-frequency data. Additionally, the importance of the ability to remotely monitor the system through a recently deployed wireless connection is emphasized by examining causes of prior data losses, and how such losses may be prevented through the ability to react when environmental or power disturbances cause system interruption and data loss.

Submersible UV-Vis Spectroscopy for Quantifying Streamwater Organic Carbon Dynamics: Implementation and Challenges before and after Forest Harvest in a Headwater Stream

Directory of Open Access Journals (Sweden)

Iain Hawthorne

2012-03-01

Full Text Available Organic material, including total and dissolved organic carbon (DOC, is ubiquitous within aquatic ecosystems, playing a variety of important and diverse biogeochemical and ecological roles. Determining how land-use changes affect DOC concentrations and bioavailability within aquatic ecosystems is an important means of evaluating the effects on ecological productivity and biogeochemical cycling. This paper presents a methodology case study looking at the deployment of a submersible UV-Vis absorbance spectrophotometer (UV-Vis spectro::lyzer model, s::can, Vienna, Austria to determine stream organic carbon dynamics within a headwater catchment located near Campbell River (British Columbia, Canada. Field-based absorbance measurements of DOC were made before and after forest harvest, highlighting the advantages of high temporal resolution compared to traditional grab sampling and laboratory measurements. Details of remote deployment are described. High-frequency DOC data is explored by resampling the 30 min time series with a range of resampling time intervals (from daily to weekly time steps. DOC export was calculated for three months from the post-harvest data and resampled time series, showing that sampling frequency has a profound effect on total DOC export. DOC exports derived from weekly measurements were found to underestimate export by as much as 30% compared to DOC export calculated from high-frequency data. Additionally, the importance of the ability to remotely monitor the system through a recently deployed wireless connection is emphasized by examining causes of prior data losses, and how such losses may be prevented through the ability to react when environmental or power disturbances cause system interruption and data loss.

A study of the composition of the products of laser-induced breakdown of hexogen, octogen, pentrite and trinitrotoluene using selected ion flow tube mass spectrometry and UV-Vis spectrometry

Czech Academy of Sciences Publication Activity Database

Sovová, Kristýna; Dryahina, Kseniya; Španěl, Patrik; Kyncl, M.; Civiš, Svatopluk

2010-01-01

Roč. 135, č. 5 (2010), s. 1106-1114 ISSN 0003-2654 R&D Projects: GA AV ČR IAAX00100903; GA ČR GA202/09/0800 Institutional research plan: CEZ:AV0Z40400503 Keywords : hexogen * UV-vis spectrometry * mass spectrometry Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.913, year: 2010

Theoretical solid state physics

CERN Document Server

Haug, Albert

2013-01-01

Theoretical Solid State Physics, Volume 1 focuses on the study of solid state physics. The volume first takes a look at the basic concepts and structures of solid state physics, including potential energies of solids, concept and classification of solids, and crystal structure. The book then explains single-electron approximation wherein the methods for calculating energy bands; electron in the field of crystal atoms; laws of motion of the electrons in solids; and electron statistics are discussed. The text describes general forms of solutions and relationships, including collective electron i

Library of UV-Vis-NIR reflectance spectra of modern organic dyes from historic pattern-card coloured papers.

Science.gov (United States)

Montagner, Cristina; Bacci, Mauro; Bracci, Susanna; Freeman, Rachel; Picollo, Marcello

2011-09-01

An accurate characterisation of the organic dyes used in artworks, especially those made of paper, is an important factor in designing safe conservation treatments. In the case of synthetic organic dyes used in modern works of art, for example, one frequently encountered difficulty is that some of these dyes are not still commercially available. Recognizing this problem, the authors of this paper present the results of an analysis of UV-Vis-NIR fibre optic reflectance spectra of 82 samples of dyed paper prepared with 41 dyes. The samples come from a historic book, The Dyeing of Paper in the Pulp, which was published by Interessen-Gemeinschaft (I.G.) Farbenindustrie in 1925. The dyes used in the paper pulp belong to the azo compounds, acridine, anthraquinone, azine, diphenylmethane, indigoid, methine, nitro, quinoline, thiazine, triphenylmethane, sulphur and xanthene classes. Copyright © 2011 Elsevier B.V. All rights reserved.

Measurement of internal quality of watermelon by Vis/NIR diffuse transmittance technique

Science.gov (United States)

Tian, Haiqing; Xu, Huirong; Ying, Yibin; Lu, Huishan; Yu, Haiyan

2006-10-01

Watermelon is a popular fruit in the world. Soluble solids content (SSC) is major characteristic used for assessing watermelon internal quality. This study was about a method for nondestructive internal quality detection of watermelons by means of visible/Near Infrared (Vis/NIR) diffuse transmittance technique. Vis/NIR transmittance spectra of intact watermelons were acquired using a low-cost commercially available spectrometer when the watermelon was in motion (1.4m/s) and in static state. Spectra data were analyzed by partial least squares (PLS) method. The influences of different data preprocessing and spectra treatments were also investigated. Performance of different models was assessed in terms of root mean square errors of calibration (RMSEC), root mean square errors of prediction (RMSEP) and correlation coefficient (r) between the predicted and measured parameter values. Results showed that spectra data preprocessing influenced the performance of the calibration models and the PLS method can provide good results. The nondestructive Vis/NIR measurements provided good estimates of SSC index of watermelon both in motion and in static state, and the predicted values were highly correlated with destructively measured values. The results indicated the feasibility of Vis/NIR diffuse transmittance spectral analysis for predicting watermelon internal quality in a nondestructive way.

Study on molecular structure, spectroscopic properties (FTIR and UV-Vis), NBO, QTAIM, HOMO-LUMO energies and docking studies of 5-fluorouracil, a substance used to treat cancer.

Science.gov (United States)

Almeida, Michell O; Barros, Daiane A S; Araujo, Sheila C; Faria, Sergio H D M; Maltarollo, Vinicius G; Honorio, Kathia M

2017-09-05

Cancer cells can expand to other parts of body through blood system and nodes from a mechanism known as metastasis. Due to the large annual growth of cancer cases, various biological targets have been studied and related to this disorder. A very interesting target related to cancer is human epidermal growth factor receptor 2 (HER2). In this study, we analyzed the main intermolecular interactions between a drug used in the cancer treatment (5-fluorouracil) and HER2. Molecular modeling methods were also employed to assess the molecular structure, spectroscopic properties (FTIR and UV-Vis), NBO, QTAIM and HOMO-LUMO energies of 5-FU. From the docking simulations it was possible to analyze the interactions that occur between some residues in the binding site of HER2 and 5-FU. To validate the choice of basis set that was used in the NBO and QTAIM analyses, theoretical calculations were performed to obtain FT-IR and UV/Vis spectra, and the theoretical results are consistent with the experimental data, showing that the basis set chosen is suitable. For the maximum λ from the theoretical calculation (254.89nm) of UV/Vis, the electronic transition from HOMO to LUMO occurs at 4.89eV. From NBO analyses, we observed interactions between Asp863 and 5-FU, i.e. the orbitals with high transfer of electrons are LP O 15 (donor NBO) and BD* (π) N 1 -H 10 (acceptor NBO), being that the value of this interaction is 7.72kcal/mol. Results from QTAIM indicate one main intermolecular H bond, which is necessary to stabilize the complex formed between the ligands and the biological target. Therefore, this study allowed a careful evaluation on the main structural, spectroscopic and electronic properties involved in the interaction between 5-FU and HER2, an important biological complex related to the cancer treatment. Copyright © 2017 Elsevier B.V. All rights reserved.

UV-VIS absorption spectra of molten AgCl and AgBr and of their mixtures with group I and II halide salts

Energy Technology Data Exchange (ETDEWEB)

Greening, Giorgio G.W. [Technische Universitaet Darmstadt (Germany). Eduard-Zintl-Institut fuer Anorganische und Physikalische Chemie

2015-07-01

The UV-VIS absorption spectra of (Ag{sub 1-X}[Li-Cs, Ba]{sub X})Cl and of (Ag{sub 1-X}[Na, K, Cs]{sub X})Br at 823 K at the concentrations X=0.0, 0.1, 0.2 have been measured. The findings show that on adding the respective halides to molten silver chloride and silver bromide, shifts of the fundamental absorption edge to shorter wavelengths result. A correlation between the observed shifts and the expansion of the silver sub-lattice is found, which is valid for both silver halide systems studied in this work.

The possibility of using plastic detectors CR-39 as UV dosimeters

International Nuclear Information System (INIS)

Shweikani, R.; Raja, G.; Sawaf, A.A.

2004-01-01

The effects of solar ultraviolet (SUV) and ultraviolet type A (UVA) produced by a solar UV simulator on CR-39 detectors were studied. This was done using three techniques: 1 - Alpha tracks diameters and tracks densities, 2 - UV-Vis spectrometry and 3 - FTIR spectrometry. The detectors were divided into two groups, the first was exposed to UV and then to alpha particles, the second group was exposed to alpha particles first and then to UV. The results showed that the effect of UVA on CR-39 was not clear using the three techniques. While, the effect of SUV was clear when using UV-Vis and FTIR spectrometric, and not clear when using track parameters. (author)

The possibility of using plastic detectors CR-39 as UV dosimeters

International Nuclear Information System (INIS)

Shweikani, R.; Raja, G.; Sawaf, A.A.

2002-01-01

The effects of solar ultraviolet (SUV) and ultraviolet type A (UVA) produced by a solar UV simulator on CR-39 detectors were studied. This was done using three techniques: 1 - Alpha tracks diameters and tracks densities, 2 - UV-Vis spectrometry and 3 - FTIR spectrometry. The detectors were divided into two groups, the first was exposed to UV and then to alpha particles, the second group was exposed to alpha particles first and then to UV. The results showed that the effect of UVA on CR-39 was not clear using the three techniques. While, the effect of SUV was clear when using UV-Vis and FTIR spectrometric, and not clear when using track parameters

Solid state radiation dosimetry

International Nuclear Information System (INIS)

Moran, P.R.

1976-01-01

Important recent developments provide accurate, sensitive, and reliable radiation measurements by using solid state radiation dosimetry methods. A review of the basic phenomena, devices, practical limitations, and categories of solid state methods is presented. The primary focus is upon the general physics underlying radiation measurements with solid state devices

Headspace single-drop microextraction coupled to microvolume UV-vis spectrophotometry for iodine determination

International Nuclear Information System (INIS)

Pena-Pereira, Francisco; Lavilla, Isela; Bendicho, Carlos

2009-01-01

Headspace single-drop microextraction has been combined with microvolume UV-vis spectrophotometry for iodine determination. Matrix separation and preconcentration of iodide following in situ volatile iodine generation and extraction into a microdrop of N,N'-dimethylformamide is performed. An exhaustive characterization of the microextraction system and the experimental variables affecting iodine generation from iodide was carried out. The procedure employed consisted of exposing 2.5 μL of N,N'-dimethylformamide to the headspace of a 10 mL acidic (H 2 SO 4 2 mol L -1 ) aqueous solution containing 1.7 mol L -1 Na 2 SO 4 for 7 min. Addition of 1 mL of H 2 O 2 1 mol L -1 for in situ iodine generation was performed. The limit of detection was determined as 0.69 μg L -1 . The repeatability, expressed as relative standard deviation, was 4.7% (n = 6). The calibration working range was from 5 to 200 μg L -1 (r 2 = 0.9991). The large preconcentration factor obtained, ca. 623 in only 7 min, compensate for the 10-fold loss in sensitivity caused by the decreased optical path, which results in improved detection limits as compared to spectrophotometric measurements carried out with conventional sample cells. The method was successfully applied to the determination of iodine in water, pharmaceutical and food samples

Luminescence and the solid state

CERN Document Server

Ropp, Richard C

2013-01-01

Since the discovery of the transistor in 1948, the study of the solid state has been burgeoning. Recently, cold fusion and the ceramic superconductor have given cause for excitement. There are two approaches possible to this area of science, namely, that of solid state physics and solid state chemistry, although both overlap extensively. The former is more concerned with electronic states in solids (including electromagnetics) whereas the latter is more concerned with interactions of atoms in solids. The area of solid state physics is well documented, however, there are very few texts which de

Solid state video cameras

CERN Document Server

Cristol, Y

2013-01-01

Solid State Video Cameras reviews the state of the art in the field of solid-state television cameras as compiled from patent literature. Organized into 10 chapters, the book begins with the basic array types of solid-state imagers and appropriate read-out circuits and methods. Documents relating to improvement of picture quality, such as spurious signal suppression, uniformity correction, or resolution enhancement, are also cited. The last part considerssolid-state color cameras.

Precipitação seletiva de tamanhos em nanopartículas semicondutoras coloidais de CdTe e CdSe: um estudo por espectroscopia UV-VIS

Directory of Open Access Journals (Sweden)

Lívia Cristina de Souza Viol

2011-01-01

Full Text Available The post-preparative size-selective precipitation technique was applied in CdTe and CdSe semiconductor nanocrystals prepared via colloidal route in water. The synthesis of CdTe and CdSe nanoparticles and the effect of the post-preparative size-selective precipitation have been characterized mainly by mean of ultraviolet and visible absorption spectroscopy (UV-Vis. It was demonstrated that the size-selective precipitation are able to isolate particles of different sizes and purify the nanoparticles as well.

Solvent Dependency of the UV-Vis Spectrum of Indenoisoquinolines: Role of Keto-Oxygens as Polarity Interaction Probes

Science.gov (United States)

Coletta, Andrea; Castelli, Silvia; Chillemi, Giovanni; Sanna, Nico; Cushman, Mark; Pommier, Yves; Desideri, Alessandro

2013-01-01

Indenoisoquinolines are the most promising non-campthotecins topoisomerase IB inhibitors. We present an integrated experimental/computational investigation of the UV-Vis spectra of the IQNs parental compound (NSC314622) and two of its derivatives (NSC724998 and NSC725776) currently undergoing Phase I clinical trials. In all the three compounds a similar dependence of the relative absorption intensities at 270 nm and 290 nm on solvent polarity is found. The keto-oxygens in positions 5 and 11 of the molecular scaffold of the molecule are the principal chromophores involved in this dependence. Protic interactions on these sites are also found to give rise to absorptions at wavelength <250 nm observed in water solution, due to the stabilization of highly polarized tautomers of the molecule. These results suggest that the keto-oxygens are important polarizable groups that can act as useful interactors with the molecular receptor, providing at the same time an useful fingerprint for the monitoring of the drug binding to topoisomerase IB. PMID:24086299

Characterization of phenolics by LC-UV/vis, LC-MS/MS and sugars by GC in Melicoccus bijugatus Jacq. 'Montgomery' fruits.

Science.gov (United States)

Bystrom, Laura M; Lewis, Betty A; Brown, Dan L; Rodriguez, Eloy; Obendorf, Ralph L

2008-12-15

Fruits of the native South American tree Melicoccus bijugatus Jacq. (Sapindaceae) are consumed for both dietary and medicinal purposes, but limited information is available about the phytochemistry and health value of M. bijugatus fruits. Fruit tissues of the Florida Montgomery cultivar were assessed for sugars, using gas chromatography, and for total phenolics, using UV spectroscopy. Reverse phase high performance liquid chromatography (HPLC) fingerprints of crude methanolic pulp, embryo and seed coat extracts were obtained at 280 nm. Phenolics were characterised by both HPLC UV/vis analysis and HPLC electrospray ionization tandem mass spectrometry. Major sugars detected in the pulp and embryo extracts were sucrose, followed by glucose and fructose. The glucose:fructose ratio was 1:1 in the pulp and 0.1:1 in the embryo. Total phenolic concentrations of the fruit tissues were in the order: seed coat > embryo > pulp. Phenolic acids were identified mostly in pulp tissues. Phenolic acids, flavonoids, procyanidins and catechins were identified in embryo tissues, and higher molecular weight procyanidins were identified in seed coat tissues. This study provides new information about the phytochemistry and the potential health value of the Montgomery cultivar M. bijugatus fruit tissues.

UV-Vis spectroscopy and solvatochromism of the tyrosine kinase inhibitor AG-1478

Science.gov (United States)

Khattab, Muhammad; Wang, Feng; Clayton, Andrew H. A.

2016-07-01

The effect of twenty-one solvents on the UV-Vis spectrum of the tyrosine kinase inhibitor AG-1478 was investigated. The absorption spectrum in the range 300-360 nm consisted of two partially overlapping bands at approximately 340 nm and 330 nm. The higher energy absorption band was more sensitive to solvent and exhibited a peak position that varied from 327 nm to 336 nm, while the lower energy absorption band demonstrated a change in peak position from 340 nm to 346 nm in non-chlorinated solvents. The fluorescence spectrum of AG-1478 was particularly sensitive to solvent. The wavelength of peak intensity varied from 409 nm to 495 nm with the corresponding Stokes shift in the range of 64 nm to 155 nm (4536 cm- 1 to 9210 cm- 1). We used a number of methods to assess the relationship between spectroscopic properties and solvent properties. The detailed analysis revealed that for aprotic solvents, the peak position of the emission spectrum in wavenumber scale correlated with the polarity (dielectric constant or ET(30)) of the solvent. In protic solvents, a better correlation was observed between the hydrogen bonding power of the solvent and the position of the emission spectrum. Moreover, the fluorescence quantum yields were larger in aprotic solvents as compared to protic solvents. This analysis underscores the importance of polarity and hydrogen-bonding environment on the spectroscopic properties of AG-1478. These studies will assume relevance in understanding the interaction of AG-1478 in vitro and in vivo.

UV-Vis spectroscopy and solvatochromism of the tyrosine kinase inhibitor AG-1478.

Science.gov (United States)

Khattab, Muhammad; Wang, Feng; Clayton, Andrew H A

2016-07-05

The effect of twenty-one solvents on the UV-Vis spectrum of the tyrosine kinase inhibitor AG-1478 was investigated. The absorption spectrum in the range 300-360nm consisted of two partially overlapping bands at approximately 340nm and 330nm. The higher energy absorption band was more sensitive to solvent and exhibited a peak position that varied from 327nm to 336nm, while the lower energy absorption band demonstrated a change in peak position from 340nm to 346nm in non-chlorinated solvents. The fluorescence spectrum of AG-1478 was particularly sensitive to solvent. The wavelength of peak intensity varied from 409nm to 495nm with the corresponding Stokes shift in the range of 64nm to 155nm (4536cm(-1) to 9210cm(-1)). We used a number of methods to assess the relationship between spectroscopic properties and solvent properties. The detailed analysis revealed that for aprotic solvents, the peak position of the emission spectrum in wavenumber scale correlated with the polarity (dielectric constant or ET(30)) of the solvent. In protic solvents, a better correlation was observed between the hydrogen bonding power of the solvent and the position of the emission spectrum. Moreover, the fluorescence quantum yields were larger in aprotic solvents as compared to protic solvents. This analysis underscores the importance of polarity and hydrogen-bonding environment on the spectroscopic properties of AG-1478. These studies will assume relevance in understanding the interaction of AG-1478 in vitro and in vivo. Copyright © 2016 Elsevier B.V. All rights reserved.

Chlorine Dioxide-Iodide-Methyl Acetoacetate Oscillation Reaction Investigated by UV-Vis and Online FTIR Spectrophotometric Method

Directory of Open Access Journals (Sweden)

Laishun Shi

2012-01-01

Full Text Available In order to study the chemical oscillatory behavior and mechanism of a new chlorine dioxide-iodide ion-methyl acetoacetate reaction system, a series of experiments were done by using UV-Vis and online FTIR spectrophotometric method. The initial concentrations of methyl acetoacetate, chlorine dioxide, potassium iodide, and sulfuric acid and the pH value have great influence on the oscillation observed at wavelength of 289 nm. There is a preoscillatory or induction period, and the amplitude and the number of oscillations are associated with the initial concentration of reactants. The equations for the triiodide ion reaction rate changing with reaction time and the initial concentrations in the oscillation stage were obtained. Oscillation reaction can be accelerated by increasing temperature. The apparent activation energies in terms of the induction period and the oscillation period were 26.02 KJ/mol and 17.65 KJ/mol, respectively. The intermediates were detected by the online FTIR analysis. Based upon the experimental data in this work and in the literature, a plausible reaction mechanism was proposed for the oscillation reaction.

Compact Solid-State 213 nm Laser Enables Standoff Deep Ultraviolet Raman Spectrometer: Measurements of Nitrate Photochemistry.

Science.gov (United States)

Bykov, Sergei V; Mao, Michael; Gares, Katie L; Asher, Sanford A

2015-08-01

We describe a new compact acousto-optically Q-switched diode-pumped solid-state (DPSS) intracavity frequency-tripled neodymium-doped yttrium vanadate laser capable of producing ~100 mW of 213 nm power quasi-continuous wave as 15 ns pulses at a 30 kHz repetition rate. We use this new laser in a prototype of a deep ultraviolet (UV) Raman standoff spectrometer. We use a novel high-throughput, high-resolution Echelle Raman spectrograph. We measure the deep UV resonance Raman (UVRR) spectra of solid and solution sodium nitrate (NaNO3) and ammonium nitrate (NH4NO3) at a standoff distance of ~2.2 m. For this 2.2 m standoff distance and a 1 min spectral accumulation time, where we only monitor the symmetric stretching band, we find a solid state NaNO3 detection limit of ~100 μg/cm(2). We easily detect ~20 μM nitrate water solutions in 1 cm path length cells. As expected, the aqueous solutions UVRR spectra of NaNO3 and NH4NO3 are similar, showing selective resonance enhancement of the nitrate (NO3(-)) vibrations. The aqueous solution photochemistry is also similar, showing facile conversion of NO3(-) to nitrite (NO2(-)). In contrast, the observed UVRR spectra of NaNO3 and NH4NO3 powders significantly differ, because their solid-state photochemistries differ. Whereas solid NaNO3 photoconverts with a very low quantum yield to NaNO2, the NH4NO3 degrades with an apparent quantum yield of ~0.2 to gaseous species.

Exploring Space Weathering on Mercury Using Global UV-VIS Reflectance Spectroscopy

Science.gov (United States)

Izenberg, N. R.; Denevi, B. W.

2018-05-01

We apply UV analysis methods used on lunar LROC data to Mercury to explore space weathering maturity and possibly evidence of shocked minerals. What says the UV // about shock, maturity // on dear Mercury?

Solid-state deep blue and UV fluorescent dyes based on para-bis(2-thienyl)phenylene

Energy Technology Data Exchange (ETDEWEB)

Krajčovič, Jozef; Kovalenko, Alexander, E-mail: kovalenko.alx@gmail.com; Heinrichová, Patricie; Vala, Martin; Weiter, Martin

2015-11-15

Despite the general rule of strong acceptor substituents having a tendency to quench fluorescence due to molecular stacking, it is shown how tetra-fluorination of the central phenylene unit of para-bis(2-thienyl)phenylene can augment the quantum yields of solid state fluorescent dyes. Another significant part of the present research was the study of the influence of the position of the solubilization alkyl chains position on the fluorescent properties of the abovementioned non- and tetra-fluorinated materials. Tenfold augmentation of quantum yields, depending on the position of the alkyl chains is reported. - Highlights: • Solid state luminescence was observed in para-bis(2-thienyl)phenylene molecules. • Quantum yields was augmented by polyfluorination of the central phenylene unit. • Tenfold augmentation of luminescence was observed by changing alkyls position. • Possibilities of steric hindrance and charge transfer were studied.

Characterization of sp3 bond content of carbon films deposited by high power gas injection magnetron sputtering method by UV and VIS Raman spectroscopy

Science.gov (United States)

Zdunek, Krzysztof; Chodun, Rafał; Wicher, Bartosz; Nowakowska-Langier, Katarzyna; Okrasa, Sebastian

2018-04-01

This paper presents the results of investigations of carbon films deposited by a modified version of the magnetron sputtering method - HiPGIMS (High Power Gas Injection Magnetron Sputtering). In this experiment, the magnetron system with inversely polarized electrodes (sputtered cathode at ground potential and positively biased, spatially separated anode) was used. This arrangement allowed us to conduct the experiment using voltages ranging from 1 to 2 kV and a power supply system equipped with 25/50 μF capacitor battery. Carbon films were investigated by VIS/UV Raman spectroscopy. Sp3/sp2 bonding ratio was evaluated basing the elementary components of registered spectra. Our investigation showed that sp3 bond content increases with discharge power but up to specific value only. In extreme conditions of generating plasma impulses, we detected a reversed relation of the sp3/sp2 ratio. In our opinion, a energy of plasma pulse favors nucleation of a sp3 phase because of a relatively higher ionization state but in extreme cases the influence of energy is reversed.

Characterization of sp3 bond content of carbon films deposited by high power gas injection magnetron sputtering method by UV and VIS Raman spectroscopy.

Science.gov (United States)

Zdunek, Krzysztof; Chodun, Rafał; Wicher, Bartosz; Nowakowska-Langier, Katarzyna; Okrasa, Sebastian

2018-04-05

This paper presents the results of investigations of carbon films deposited by a modified version of the magnetron sputtering method - HiPGIMS (High Power Gas Injection Magnetron Sputtering). In this experiment, the magnetron system with inversely polarized electrodes (sputtered cathode at ground potential and positively biased, spatially separated anode) was used. This arrangement allowed us to conduct the experiment using voltages ranging from 1 to 2kV and a power supply system equipped with 25/50μF capacitor battery. Carbon films were investigated by VIS/UV Raman spectroscopy. Sp 3 /sp 2 bonding ratio was evaluated basing the elementary components of registered spectra. Our investigation showed that sp 3 bond content increases with discharge power but up to specific value only. In extreme conditions of generating plasma impulses, we detected a reversed relation of the sp 3 /sp 2 ratio. In our opinion, a energy of plasma pulse favors nucleation of a sp 3 phase because of a relatively higher ionization state but in extreme cases the influence of energy is reversed. Copyright © 2018 Elsevier B.V. All rights reserved.

One-step immobilization of tris(2,2'-bipyridyl)ruthenium(II) via vapor-surface sol-gel deposition towards solid-state electrochemiluminescence detection

International Nuclear Information System (INIS)

Qian Lei; Yang Xiurong

2008-01-01

A novel method for immobilization of tris(2,2'-bipyridyl)ruthenium(II) (Ru(bpy) 3 Cl 2 ) on electrode surfaces based on the vapor-surface sol-gel deposition strategy is first demonstrated in this paper. Ru(bpy) 3 Cl 2 immobilized sol-gel (Ru(bpy) 3 Cl 2 /sol-gel) films were characterized by UV-vis spectroscopy and field-emitted scanning electron microscopy (FE-SEM). These results showed that Ru(bpy) 3 Cl 2 was successfully incorporated into the silica sol-gel film. It was found that many irregular Ru(bpy) 3 Cl 2 /sol-gel clusters were formed on surfaces through one deposition and thick sol-gel films were observed after further deposition. Electrochemical properties and electrochemiluminescence (ECL) behaviors of Ru(bpy) 3 Cl 2 /sol-gel films could be easily adjusted by deposition numbers and time. At last, the Ru(bpy) 3 Cl 2 /sol-gel film modified electrode was used for solid-state ECL detection of tripropylamine. The linear range was from 5.8 x 10 -8 to 2.4 x 10 -4 M with the detection limit of 5 nM, which was three orders of magnitude lower than that from pure Nafion-modified electrodes. The ECL sensor also exhibited high stability, and still remained 92% response after being stored in air for 35 days. This method for immobilization of Ru(bpy) 3 Cl 2 is simple, convenient and low-cost relative to others, so it shows promising applications in solid-state ECL detection

Single crystal growth of yttrium calcium oxy borate (YCOB) crystals by flux technique and their characterization. CP-3.5

International Nuclear Information System (INIS)

Arun Kumar, R.; Senthilkumar, M.; Dhanasekaran, R.

2007-01-01

Yttrium calcium oxy borate single crystals were grown by the flux technique for the first time. Polycrystalline YCOB material was prepared by solid state reaction method. Single crystals of YCOB were grown using boron-tri-oxide flux. Several transparent single crystals of dimensions 10 x 5 x 5 mm 3 were obtained. The grown crystals were characterized by powder XRD and UV- VIS-NIR studies. The results of powder XRD confirm the crystalline structure of YCOB. The UV- VIS-NIR transmission spectrum reveals that the crystal is highly transparent (above 75%) from ultraviolet (220 nm) to near IR regions enabling it as a suitable candidate for high power UV applications

Online in-tube microextractor coupled with UV-Vis spectrophotometer for bisphenol A detection.

Science.gov (United States)

Poorahong, Sujittra; Thammakhet, Chongdee; Thavarungkul, Panote; Kanatharana, Proespichaya

2013-01-01

A simple and high extraction efficiency online in-tube microextractor (ITME) was developed for bisphenol A (BPA) detection in water samples. The ITME was fabricated by a stepwise electrodeposition of polyaniline, polyethylene glycol and polydimethylsiloxane composite (CPANI) inside a silico-steel tube. The obtained ITME coupled with UV-Vis detection at 278 nm was investigated. By this method, the extraction and pre-concentration of BPA in water were carried out in a single step. Under optimum conditions, the system provided a linear dynamic range of 0.1 to 100 μM with a limit of detection of 20 nM (S/N ≥3). A single in-tube microextractor had a good stability of more than 60 consecutive injections for 10.0 μM BPA with a relative standard deviation of less than 4%. Moreover, a good tube-to-tube reproducibility and precision were obtained. The system was applied to detect BPA in water samples from six brands of baby bottles and the results showed good agreement with those obtained from the conventional GC-MS method. Acceptable percentage recoveries from the spiked water samples were obtained, ranging from 83-102% for this new method compared with 73-107% for the GC-MS standard method. This new in-tube CPANI microextractor provided an excellent extraction efficiency and a good reproducibility. In addition, it can also be easily applied for the analysis of other polar organic compounds contaminated in water sample.

Evaluation of clinoptilolite for removal of ammoniacal nitrogen produced in aquaculture by Neutron activation analysis and UV-VIS spectrophotometry

International Nuclear Information System (INIS)

Bibiano C, L.; Iturbe G, J.L.; Lopez M, B.E.; Martinez M, V.

1997-01-01

In fish culture system, ammonia is excreted in the water as a metabolic by-product. In this work, sorption properties of clinoptilolite were determined and it was applied in culture of the rainbow trout Oncorhynchus mykiss for the removal of the ammoniacal nitrogen. The original clinoptilolite was treated with 1N NaCl solution from 24 to 192 h, for exchange NH 4 ions produced in fish culture. The content of Na in the clinoptilolite was determined by neutron activation analysis. The ammonium ion content in the exchange was analysed by UV-VIS spectrophotometry. Maximum uptake of sodium was reached between 24 and 48 hours at neutral pH with granules of the clinoptilolite from 14 to 24 mesh size. The adsorption capacity was from 3.28 to 6.8 mg of ammonium per gram of clinoptilolite. (Author)

Modeling the natural UV irradiation and comparative UV measurements at Moussala BEO (BG)

Science.gov (United States)

Tyutyundzhiev, N.; Angelov, Ch; Lovchinov, K.; Nitchev, Hr; Petrov, M.; Arsov, T.

2018-03-01

Studies of and modeling the impact of natural UV irradiation on the human population are of significant importance for human activity and economics. The sharp increase of environmental problems – extraordinary temperature changes, solar irradiation abnormalities, icy rains – raises the question of developing novel means of assessing and predicting potential UV effects. In this paper, we discuss new UV irradiation modeling based on recent real-time measurements at Moussala Basic Environmental Observatory (BEO) on Moussala Peak (2925 m ASL) in Rila Mountain, Bulgaria, and highlight the development and initial validation of portable embedded devices for UV-A, UV-B monitoring using open-source software architecture, narrow bandpass UV sensors, and the popular Arduino controllers. Despite the high temporal resolution of the VIS and UV irradiation measurements, the results obtained reveal the need of new assumptions in order to minimize the discrepancy with available databases.

Concomitant monitoring of implant formation and drug release of in situ forming poly (lactide-co-glycolide acid) implants in a hydrogel matrix mimicking the subcutis using UV-vis imaging.

Science.gov (United States)

Sun, Yu; Jensen, Henrik; Petersen, Nickolaj J; Larsen, Susan W; Østergaard, Jesper

2018-02-20

For poly (lactide-co-glycolide acid) (PLGA)-based in situ forming implants, the rate of implant formation plays an important role in determining the overall drug release kinetics. Currently, in vitro techniques capable of characterizing the processes of drug release and implant formation at the same time are not available. A hydrogel-based in vitro experimental setup was recently developed requiring only microliter of formulation and forming a closed system potentially suitable for interfacing with various spectroscopic techniques. The aim of the present proof-of-concept study was to investigate the feasibility of concomitant UV imaging, Vis imaging and light microscopy for detailed characterization of the behavior of in situ forming PLGA implants in the hydrogel matrix mimicking the subcutis. The model compounds, piroxicam and α-lactalbumin were added to PLGA-1-methyl-2-pyrrolidinone and PLGA-triacetin solutions. Upon bringing the PLGA-solvent-compound pre-formulation in contact with the hydrogel, Vis imaging and light microscopy were applied to visualize the depot formation and UV imaging was used to quantify drug transport in the hydrogel. As compared to piroxicam, the α-lactalbumin invoked an acceleration of phase separation and an increase of implant size. α-Lactalbumin was released faster from the PLGA-1-methyl-2-pyrrolidinone system than the PLGA-triacetin system opposite to the piroxicam release pattern. A linear relationship between the rate of implant formation and initial compound release within the first 4h was established for the PLGA-NMP systems. This implies that phase separation may be one of the controlling factors in drug release. The rate of implant formation may be an important parameter for predicting and tailoring drug release. The approach combining UV imaging, Vis imaging and light microscopy may facilitate understanding of release processes and holds potential for becoming a useful tool in formulation development of in situ forming

The effect of radiation-thermal treatment on the physicochemical properties of the Ni-Mo/Al2O3 hydrotreatment catalyst. II. UV-Vis diffuse reflectance spectra of surface compounds after irradiation

International Nuclear Information System (INIS)

Solovetskii, Yu.I.; Miroshinichenko, I.I.; Lunin, V.V.

1993-01-01

Radiation-thermal damage of the surface and the active metal phases of hydrodesulfurization Ni-Mo/Al 2 O 3 catalysts by a fast electron beam of up to 2.0 MeV energy was studied. UV-Vis diffuse reflectance spectra of the industrial and model coked systems after radiation-thermal treatment were measured. 14 refs., 2 figs

Characterization of pigment/binder - systems in arts via FTIR and UV/Vis/NIR - spectroscopy with special consideration of nondestructive methods

International Nuclear Information System (INIS)

Vetter, W.A.

2014-01-01

The main focus of this doctoral thesis is on the non-destructive analysis of art objects by using compound specific reflection-UV/Vis/NIR and reflection-FTIR spectroscopy. Based on commercially available instruments, measuring systems have been designed and built to meet the specific requirements of material analysis in the field of art. These systems have been utilized to analyse different types of art objects (watercolour paintings, easel paintings, contemporary graphic art objects) in order to identify the materials used by the artists. Furthermore, two new procedures are presented which allow to build up adequate reference databases from only minimal sample amounts of original watercolour materials of the 19th century. This is a crucial point as both methods require references for the identification of the materials. The results obtained demonstrate that UV/Vis/NIR and FTIR spectroscopy in reflection mode enable the non-destructive identification of a variety of both, organic and inorganic materials, particularly in combination with element specific XRF (X-ray fluorescence analysis) and thus are valuable tools for the analysis of cultural heritage objects. Furthermore, the results have shown that a comparison of the complementary methods strongly facilitated the evaluation of spectra obtained by the particular analytical techniques and hence reliable results could be obtained in many cases. As expected, several frequently used pigments e.g. carbon based blacks, earth pigments and lake pigments could not be identified unambiguously due to methodical limitations. Therefore, the use of additional complementary methods such as Raman spectroscopy and X-ray diffraction (XRD) would be highly desirable. Except a few examples, the characteristics of the radiation used for the investigations did not allow to draw conclusions about the distribution of materials in multilayer structures. For this reason, it still remains necessary to analyse cross-sections of samples for a

Design of UV-absorbing PVDF membrane via surface-initiated AGET ATRP

Science.gov (United States)

Dong, Li; Liu, Xiangdong; Xiong, Zhengrong; Sheng, Dekun; Zhou, Yan; Lin, Changhong; Yang, Yuming

2018-03-01

Herein, PVDF membranes with excellent UV-absorbing property were first synthesized through grafting the polymerizable low-molecular-weight organic UV-absorber 2-hydroxy-4-(3-methacryloxy-2-hydroxylpropoxy) benzophenone (BPMA) onto α-bromoester-functionalized PVDF membranes via the surface-initiated activator generated by electron transfer atom transfer radical polymerization (SI-AGET ATRP). The surface initiators were immobilized by the reaction between 2-bromoisobutyryl bromide (BIBB) and the hydroxylated PVDF membranes. PVDF-g-PBPMA membranes with different grafting densities were obtained by tuning the polymerization time and the modified membranes were characterized by 1H-NMR, FT-IR, XPS, SEM, UV-vis Spectrophotometer, TGA and DSC. The experimental results indicated that PBPMA chains were successfully introduced onto PVDF membranes. Most importantly, the PVDF-g-PBPMA membranes exhibited outstanding UV-shielding property. UV-vis transmittance spectra showed that most UV light below 360 nm could be absorbed by PVDF-g-PBPMA membranes and the whole UV light region (200-400 nm) can be blocked with the reaction time increased.

Characterization of solid UV curable 3D printer resins for biological applications

KAUST Repository

Sivashankar, Shilpa

2016-12-19

In this paper, we report a simple method to evaluate biocompatibility of solid UV cross-linked resin as a material for microfluidic devices that can be used for biological applications. We evaluated the biocompatibility of the material in two different ways (1) determining if the UV cured resin inhibits the polymerase chain reaction (PCR) and (2) observing agglutination complex formed on the surface of the UV cured resin when anti-CRP antibodies and C- reactive protein (CRP) proteins were allowed to agglutinate. Six different types of 3D printer resins were compared to test the biocompatibility. The study showed that only few among them could be used for fabrication of micro channels and that had least effect on biological molecules that could be used for PCR and protein interactions. Through these studies it is possible to estimate the curing time of various resin and their type of interaction with biomolecules. This study finds importance in on-chip tissue engineering and organ-on-chip applications.

Preparation, characterization and evaluation of moisturizing and UV protecting effects of topical solid lipid nanoparticles

Directory of Open Access Journals (Sweden)

Shiva Golmohammadzadeh

2012-12-01

Full Text Available Solid lipid nanoparticles (SLN were recently proposed as carriers for various pharmaceutical and cosmetic actives. These lipid nanoparticles can act as moisturizers and physical sunscreens on their own. Therefore, the full potential of these carriers has yet to be determined. The present study was aimed to determine and compare moisturizing and UV-protecting effects of different solid lipid nanoparticles (SLN prepared by different solid lipids including Glyceryl monostearate (GMS, Precirol® (P and cetyl palmitate (CP as carrier systems of moisturizers and sunscreens. The influence of the size and matrix crystallinity of the solid lipids on the occlusive factor, skin hydration and UV-protection were evaluated by in vitro and in vivo methods. The SLN were prepared by high-shear homogenization and ultrasound methods. Size, zeta potential and morphological characteristics of the samples were assessed by transmission electron microscopy (TEM and thermotropic properties with differential scanning calorimetry (DSC technique. Results of the assessments showed that SLN-CP significantly increases skin hydration and UV-protection, compared to SLN-GMS and SLN-P. It was demonstrated that the size of SLN, crystallinity index of solid lipid in SLN and probably other mechanisms besides the occlusive factor can influence skin hydration and UV-protection indices. Furthermore, findings of the assessments demonstrated significant difference between in vitro and in vivo assessments regarding occlusive factor and moisturizing effects. Findings of the present study indicate that the SLN-CP could be a promising carrier for sunscreens and moisturizers.Nanopartículas lipídicas sólidas (NLS foram, recentemente, propostas como carreadores de vários ativos cosméticos e farmacêuticos. Essas nanopartículas lipídicas podem atuar como hidratantes e protetores solares físicos por si só. Assim sendo, determinou-se o potencial desses carreadores. Os objetivos do

Determination of phenyl-N-methylcarbamates and their hydrolysis products in water, using solid-phase extraction and reversed-phase liquid chromatography with UV and electrospray mass spectrometric detection

International Nuclear Information System (INIS)

El Atrache, L.L.; Sabbah, S.

2003-01-01

In this study, eight phenyl-N-methylcarbamates (PNMCs) were considered. Reversed-phase LC was set up for UV and mass spectrometry (MS) detection mode. Gradient elution was used, and the mobile phase was composed of acetonitrile and water. UV-vis was performed at 220 nm. The method was tested with different reversed-phase columns. Comparison between chromatographic parameters: retention time (t R ), resolution (R S ), and selectivity (α) was established. Hydrolysis kinetics of three of the PNMCs were reported. The major hydrolysis products were determined by LC-UV, and the effect of pH on hydrolysis was also studied. Also, chromatographic separation of a mixture of PNMCs and four of their hydrolysis products was carried out. The preconcentration of 12 studied solutes was realized by solid-phase extraction. C18 extraction cartridges of 1 g were used to extract solutes from a 100 mL volume of tap and surface water spiked at 10 μg/L. The recoveries were, respectively, between 68-86% and 62-83% with relative a standard deviation of less than 11%. Limits of detection (LODs) and limits of quantitation (LOQs) ranged, respectively, from 1-4 μg/L and from 4-10 μg/L. Since standard UV detection does not provide adequate selectivity for water samples, an electrospray (ES)-MS instrument equipped with a triple quadrupole mass filter was used. MS data acquisition was performed by a time-scheduled, selected-ion monitoring (SIM) program. Limits of quantitation gave values between 0.1-0.5 μg/L. (author)

Solid-state laser engineering

CERN Document Server

Koechner, Walter

1999-01-01

Solid-State Laser Engineering, written from an industrial perspective, discusses in detail the characteristics, design, construction, and performance of solid-state lasers. Emphasis is placed on engineering and practical considerations; phenomenological aspects using models are preferred to abstract mathematical derivations. This new edition has extensively been updated to account for recent developments in the areas of diode-laser pumping, laser materials, and nonlinear crystals. Walter Koechner received a doctorate in Electrical Engineering from the University of Technology in Vienna, Austria, in 1965. He has published numerous papers in the fields of solid-state physics, optics, and lasers. Dr. Koechner is founder and president of Fibertek, Inc., a research firm specializing in the design, development, and production of advanced solid-state lasers, optical radars, and remote-sensing systems.

Simultaneous Determination of Caffeine and Chlorogenic Acids in Green Coffee by UV/Vis Spectroscopy

Directory of Open Access Journals (Sweden)

G. Navarra

2017-01-01

Full Text Available A simple method for the simultaneous determination of caffeine and chlorogenic acids content in green coffee was reported. The method was based on the use of UV/Vis absorption. It is relevant that the quantification of both caffeine and chlorogenic acids was performed without their preliminary chemical separation despite their spectral overlap in the range 250–350 nm. Green coffee was extracted with 70% ethanol aqueous solution; then the solution was analyzed by spectroscopy. Quantitative determination was obtained analytically through deconvolution of the absorption spectrum and by applying the Lambert-Beer law. The bands used for the deconvolution were the absorption bands of both caffeine and chlorogenic acids standards. The molar extinction coefficients for caffeine and chlorogenic acid in ethanol solution at 70% were calculated by using the chemical standards; the estimated values were ε(272 nm=12159±97 M−1 cm−1 for caffeine and ε(330 nm=27025±190 M−1 cm−1 for chlorogenic acids molecules, respectively. The estimate of concentration values was in agreement with the one obtained by High Performance Liquid Chromatography quantification. The method is fast and simple and allows us to realize routine controls during the coffee production. In addition, it could be applied on roasted coffee and espresso coffee.

A combined experimental (IR, Raman and UV-Vis) and quantum chemical study of canadine

Science.gov (United States)

Joshi, Bhawani Datt; Srivastava, Anubha; Tandon, Poonam; Jain, Sudha; Ayala, A. P.

2018-02-01

Plant based natural products cover a major sector of the medicinal field, as such focus on plant research has been increased all over the world. As an attempt to aid that research, we have performed structural and spectroscopic analysis of a natural product, an alkaloid: canadine. Both ab initio Hartree-Fock (HF) and density functional theory (DFT) employing B3LYP using 6-311 ++G(d,p) basis set were used for the calculations. The calculated vibrational frequencies were scaled and compared with the experimental infrared and Raman spectra. The complete vibrational assignments were made using potential energy distribution. The structure-activity relation has also been interpreted by mapping electrostatic potential surface and evaluating the reactivity descriptors, which are valuable information for quality control of medicines and drug-receptor interactions. Natural bond orbital analysis has also been performed to understand the stability and hyperconjugative interactions of the molecule. Furthermore, UV-Vis spectra have been recorded in an ethanol solvent (EtOH) and the electronic property has been analyzed employing TD-DFT for both gaseous and solvent phase. The HOMO and LUMO calculation with their energy gap show that charge transfer occurs within the molecule. Additionally, the nonlinear optical properties of the title compound have been interpreted that predicts it's the best candidate for the NLO materials.

Determination of formal redox potentials in aqueous solution of copper(II) complexes with ligands having nitrogen and oxygen donor atoms and comparison with their EPR and UV-Vis spectral features.

Science.gov (United States)

Tabbì, Giovanni; Giuffrida, Alessandro; Bonomo, Raffaele P

2013-11-01

Formal redox potentials in aqueous solution were determined for copper(II) complexes with ligands having oxygen and nitrogen as donor atoms. All the chosen copper(II) complexes have well-known stereochemistries (pseudo-octahedral, square planar, square-based pyramidal, trigonal bipyramidal or tetrahedral) as witnessed by their reported spectroscopic, EPR and UV-visible (UV-Vis) features, so that a rough correlation between the measured redox potential and the typical geometrical arrangement of the copper(II) complex could be established. Negative values have been obtained for copper(II) complexes in tetragonally elongated pseudo-octahedral geometries, when measured against Ag/AgCl reference electrode. Copper(II) complexes in tetrahedral environments (or flattened tetrahedral geometries) show positive redox potential values. There is a region, always in the field of negative redox potentials which groups the copper(II) complexes exhibiting square-based pyramidal arrangements. Therefore, it is suggested that a measurement of the formal redox potential could be of great help, when some ambiguities might appear in the interpretation of spectroscopic (EPR and UV-Vis) data. Unfortunately, when the comparison is made between copper(II) complexes in square-based pyramidal geometries and those in square planar environments (or a pseudo-octahedral) a little perturbed by an equatorial tetrahedral distortion, their redox potentials could fall in the same intermediate region. In this case spectroscopic data have to be handled with great care in order to have an answer about a copper complex geometrical characteristics. © 2013.

Understanding solid state physics

CERN Document Server

Holgate, Sharon Ann

2009-01-01

Where Sharon Ann Holgate has succeeded in this book is in packing it with examples of the application of solid state physics to technology. … All the basic elements of solid state physics are covered … . The range of materials is good, including as it does polymers and glasses as well as crystalline solids. In general, the style makes for easy reading. … Overall this book succeeds in showing the relevance of solid state physics to the modern world … .-Contemporary Physics, Vol. 52, No. 2, 2011I was indeed amused and inspired by the wonderful images throughout the book, carefully selected by th

Gamma sterilization of cefotaxime sodium in the solid state

International Nuclear Information System (INIS)

Kattan, M.; Aladawi, M. A.; Hammoudeh, A.; Albaroudi, H.

2010-08-01

To investigate the effect of gamma irradiation on the solid state of Cefotaxime sodium salt (C 1 8H 1 6N 8 Na 2 O 7 S 3 ) as a member of the third generation of cephalosporin. Solid Cefotaxime as a pharmaceutical dosage was exposed to doses of 0, 5, 10, 15, 20, 25, and 50 kGy in 60 Co package irradiator. Physical and chemical characteristics of Cefotaxime sodium have been investigated by using UV (Ultra Violet) and IR (Infra Red) spectroscopic, pH, solubility and DSC (Deferential Scanning Calorimetric) methods. The biological activity of Cefotaxime sodium was investigated using Escherichia coli ATCC 25922 as a strain of bacteria. The obtained results indicated that gamma irradiation have no effect on physical and chemical characteristics of Cefotaxime sodium, No significant differences were found between irradiated and non-irradiated samples in the biological activity of Cefotaxime sodium on E. Coli. (Author)

Red light emitting solid state hybrid quantum dot-near-UV GaN LED devices

International Nuclear Information System (INIS)

Song, Hongjoo; Lee, Seonghoon

2007-01-01

We produced core-shell (CdSe)ZnSe quantum dots by direct colloidal chemical synthesis and the surface-passivation method-an overcoating of the core CdSe with a larger-bandgap material ZnSe. The (CdSe)ZnSe quantum dots(QDs) play the role of a colour conversion centre. We call these quantum dots nanophosphors. We fabricated red light emitting hybrid devices of (CdSe)ZnSe QDs and a near-UV GaN LED by combining red light emitting (CdSe)ZnSe quantum dots (as a colour conversion centre) with a near-UV(NUV) GaN LED chip (as an excitation source). A few good red phosphors have been known for UV excitation wavelengths, and red phosphors for UV excitation have been sought for a long time. Here we tested the possibility of using (CdSe)ZnSe QDs as red nanophosphors for UV excitation. The fabricated red light emitting hybrid device of (CdSe)ZnSe and a NUV GaN LED chip showed a good luminance. We demonstrated that the (CdSe)ZnSe quantum dots were promising red nanophosphors for NUV excitation and that a red LED made of QDs and a NUV excitation source was a highly efficient hybrid device

Investigating the Dissolution Performance of Amorphous Solid Dispersions Using Magnetic Resonance Imaging and Proton NMR

Directory of Open Access Journals (Sweden)

Francesco Tres

2015-09-01

Full Text Available We have investigated the dissolution performance of amorphous solid dispersions of poorly water-soluble bicalutamide in a Kollidon VA64 polymeric matrix as a function of the drug loading (5% vs. 30% bicalutamide. A combined suite of state-of-the-art analytical techniques were employed to obtain a clear picture of the drug release, including an integrated magnetic resonance imaging UV-Vis flow cell system and 1H-NMR. Off-line 1H-NMR was used for the first time to simultaneously measure the dissolution profiles and rates of both the drug and the polymer from a solid dispersion. MRI and 1H-NMR data showed that the 5% drug loading compact erodes linearly, and that bicalutamide and Kollidon VA64 are released at approximately the same rate from the molecular dispersion. For the 30% extrudate, data indicated a slower water ingress into the compact which corresponds to a slower dissolution rate of both bicalutamide and Kollidon VA64.

Polycrystalline diamond film UV detectors for excimer lasers

International Nuclear Information System (INIS)

Ralchenko, V G; Savel'ev, A V; Konov, Vitalii I; Mazzeo, G; Spaziani, F; Conte, G; Polyakov, V I

2006-01-01

Photoresistive metal-semiconductor-metal detectors based on polycrystalline diamond films are fabricated for recording cw and pulsed UV radiation. The detectors have a high spectral selectivity (the UV-to-VIS response ratio is ∼10 5 ) and a temporal resolution of the order of 10 9 s. 'Solar-blind' photostable diamond detectors are promising for applications in UV lithography, laser micromachining, medicine, and space research. (letters)

Model for UV induced formation of gold nanoparticles in solid polymeric matrices

Science.gov (United States)

Sapogova, N.; Bityurin, N.

2009-09-01

UV irradiation of polymeric PMMA films containing HAuCl 4 followed by annealing at 60-80 °C forms gold nanoparticles directly within the bulk material. The kinetics of nanoparticle formation was traced by extinction spectra of nanocomposite film changes vs annealing time. We propose that UV irradiation causes HAuCl 4 dissociation and thus provides a polymeric matrix with atomic gold. The presence of an oversaturated solid solution of atomic gold in the polymeric matrix leads to Au nanoparticle formation during annealing. This process can be understood as a phase transition of the first order. In this paper we apply several common kinetic models of the phase transition for describing Au nanoparticle formation inside the solid polymer matrix. We compare predictions of these models with the experimental data and show that these models cannot describe the process. We propose that the stabilization effect of the matrix on the growing gold nanoparticles is important. The simplest model introducing some probability for the transition from growing nanoparticle to the non-growing, stabilized form is suggested. It is shown that this model satisfactorily describes the experimentally observed evolution of the extinction spectrum of Au nanoparticles forming in a polymer matrix.

Highly efficient red-emitting BaMgBO3F:Eu3+,R+ (R: Li, Na, K, Rb) phosphor for near-UV excitation synthesized via glass precursor solid-state reaction

Science.gov (United States)

Shinozaki, Kenji; Akai, Tomoko

2017-09-01

Eu3+-doped fluoroborate crystals of BaMgBO3F were synthesized by a solid-state reaction using a glassy precursor material, and their photoluminescence (PL) was investigated. To compensate for the incorporation of Eu3+ into Ba2+ sites, samples codoped with alkali ions (Li+, Na+, K+, Rb+) were also prepared. The Eu3+-doped sample showed red PL with a quantum yield (QY) of 65% caused by near-UV excitation (λ = 393 nm), and PL intensity and QY increased with the codoping of Eu3+ and alkali ions. It was found that the Eu3+,Li+-codoped sample showed the highest PL intensity and a QY of 83%.

Assessment of gamma radiolytic degradation in waste lubricating oil by GC/MS and UV/VIS

Science.gov (United States)

Scapin, Marcos A.; Duarte, Celina L.; Bustillos, José Oscar W. V.; Sato, Ivone M.

2009-07-01

The hydrocarbons degradation by gamma irradiation of the waste automotive lubricating oil at different absorbed doses has was investigated. The waste automotive oil in a Brazilian oil recycling company was collected. This sample was fractioned and 50% and 70% (v/v) Milli-Q water were added. Each sample was irradiated with 100, 200 and 500 kGy doses using a gamma source Co-60—GAMMACELL type, with 5×10 3 Ci total activity. Gas chromatography-mass spectrometry (GC/MS) was used to identify degraded organic compounds. The mass spectra were analyzed using the mass spectral library from NIST, installed in the spectrometer. The sample irradiated at 500 kGy dose with 70% (v/v) Milli-Q water addition formed eight degradation products, namely diethanolmethylamine (C 5H 13NO), diethyldiethylene glycol (C 8H 18O 3), 1-octyn-3-ol, 4-ethyl (C 10H 18O) and 1.4-pentanediamine, N1, N1-diethyl (C 9H 22N 2). The color changing of the waste lubricating oil, for different absorbed doses, was determined by UV/VIS spectrophotometer. The related sample showed the lowest absorbance value evidencing the formation of 2-ethoxyethyl ether (C 8H 18O 3) compound.

Solid-state laser engineering

CERN Document Server

Koechner, Walter

1996-01-01

Solid-State Laser Engineering, written from an industrial perspective, discusses in detail the characteristics, design, construction, and performance of solid-state lasers. Emphasis is placed on engineering and practical considerations; phenomenological aspects using models are preferred to abstract mathematical derivations. This new edition has extensively been updated to account for recent developments in the areas of diode-laser pumping, mode locking, ultrashort-pulse generation etc. Walter Koechner received a doctorate in Electrical Engineering from the University of Technology in Vienna, Austria, in 1965. He has published numerous papers in the fields of solid-state physics, optics, and lasers. Dr. Koechner is founder and president of Fibertek, Inc., a research firm specializing in the design, development, and production of advanced solid-state lasers, optical radars, and remote-sensing systems.

Improving the Efficiency of Solid State Light Sources

International Nuclear Information System (INIS)

Joanna McKittrick

2003-01-01

This proposal addresses the national need to develop a high efficiency light source for general illumination applications. The goal is to perform research that would lead to the fabrication of a unique solid state, white-emitting light source. This source is based on an InGaN/GaN UV-emitting chip that activates a luminescent material (phosphor) to produce white light. White-light LEDs are commercially available which use UV from a GaN chip to excite a phosphor suspended in epoxy around the chip. Currently, these devices are relatively inefficient. This research will target one technical barrier that presently limits the efficiency of GaN based devices. Improvements in efficiencies will be achieved by improving the internal conversion efficiency of the LED die, by improving the coupling between the die and phosphor(s) to reduce losses at the surfaces, and by selecting phosphors to maximize the emissions from the LEDs in conversion to white light. The UCSD research team proposes for this project to develop new phosphors that have high quantum efficiencies that can be activated by the UV-blue (360-410 nm) light emitted by the GaN device. The main goal for the UCSD team was to develop new phosphor materials with a very specific property: phosphors that could be excited at long UV-wavelengths (λ=350-410 nm). The photoluminescence of these new phosphors must be activated with photons emitted from GaN based dies. The GaN diodes can be designed to emit UV-light in the same range (λ=350-410 nm). A second objective, which is also very important, is to search for alternate methods to fabricate these phosphors with special emphasis in saving energy and time and reduce pollution

Solid state opto-impedance of LiNiVO4 and LiMn2O4

International Nuclear Information System (INIS)

Kalyani, P; Sivasubramanian, S; Prabhu, S Naveen; Ragavendran, K; Kalaiselvi, N; Ranganathan, N G; Madhu, S; SundaraRaj, A; Manoharan, S P; Jagannathan, R

2005-01-01

Spinel type LiMn 2 O 4 and inverse spinel LiNiVO 4 systems serve as standard cathode materials or potential cathode systems for application in high energy density lithium-ion batteries. Upon photo-excitation using UV radiation of energy ∼5 eV, the LiNiVO 4 system shows significant modification in the solid state impedance pattern while the LiMn 2 O 4 system does not. This study has revealed a significant difference in the opto-impedance pattern for LiNiVO 4 with respect to LiMn 2 O 4 , which may be due to the different electronic processes involved. An attempt has been made to study this behaviour from the solid-state viewpoint

Development of Efficient UV-LED Phosphor Coatings for Energy Saving Solid State Lighting

International Nuclear Information System (INIS)

Uwe Happek

2006-01-01

The University of Georgia, in collaboration with GE Global Research, has investigated the relevant quenching mechanism of phosphor coatings used in white light devices based on UV LEDs. The final goal of the project was the design and fabrication of a high-efficacy white light UV-LED device through improved geometry and optimized phosphor coatings. At the end of the research period, which was extended to seamlessly carry over the research to a follow-up program, we have demonstrated a two-fold improvement in the conversion efficiency of a white light LED device, where the increase efficacy is due to both improved phosphor quantum efficiency and lamp geometry. Working prototypes have been displayed at DOE sponsored meetings and during the final presentation at the DOE Headquarters in Washington, DC. During the first phase of the project, a fundamental understanding of quenching processes in UV-LEDs was obtained, and the relationships that describe the performance of the phosphor as a function of photon flux, temperature, and phosphor composition were established. In the second phase of the project, these findings were then implemented to design the improved UV-LED lamp. In addition, our research provides a road map for the design of efficient white light LEDs, which will be an important asset during a follow-up project led by GE

Long-lived and largely red-shifted photoluminescence of solid-state rhodamine dyes: Molecular exciton coupling and structural effect

International Nuclear Information System (INIS)

Zhang, Xian-Fu; Zhang, Ya-Kui

2015-01-01

The optical absorption and fluorescence properties of five rhodamine dyes in solid-state are measured and show large difference from that in their gas phase or liquid solvents. All solid-state rhodamine dyes strongly absorb all light in UV and visible region, but emit only red and NIR fluorescence (680–800 nm, >100 nm red-shifted from that in solution). Further more, the absorption maxima of a solid-state rhodamine show a large red-shifted band (~100 nm) and blue-shifted peak (~125 nm) compared to that in solutions, indicating a strong molecular exciton coupling between molecules. All solid-state rhodamines still show reasonably good fluorescence quantum yield (Φ f ). In particular, solid-state Rhodamine B butyl ester and sulfonyl Rhodamine B showed a much longer emission lifetime (τ f ) than that of the corresponding molecular rhodamine, i.e. 4.12 and 4.14 ns in solid state compared to 1.61 and 2.47 ns in solution. The chemical structure of a rhodamine molecule showed dramatic effect on Φ f and τ f values for solid state rhodamine. The larger substituent in the benzene moiety favors higher Φ f and τ f values of rhodamine solids. These effects can be elucidated by the relation between structure-molecular distance and molecular exciton couplings. - Highlights: • Optical properties of solid rhodamines show large difference from that in solutions. • Solid-state rhodamine dyes emit red and NIR fluorescence (680–800 nm). • Solid-state rhodamines still show reasonably good fluorescence quantum yield. • Solid-state rhodamines have much longer fluorescence lifetimes than that in solutions

Long-lived and largely red-shifted photoluminescence of solid-state rhodamine dyes: Molecular exciton coupling and structural effect

Energy Technology Data Exchange (ETDEWEB)

Zhang, Xian-Fu, E-mail: zhangxianfu@tsinghua.org.cn [Institute of Applied Photochemistry & Center of Analysis and Measurements, Hebei Normal University of Science and Technology, Qinhuangdao 066004, Hebei Province (China); MPC Technologies, Hamilton, ON, Canada L8S 3H4 (Canada); Zhang, Ya-Kui [Institute of Applied Photochemistry & Center of Analysis and Measurements, Hebei Normal University of Science and Technology, Qinhuangdao 066004, Hebei Province (China)

2015-10-15

The optical absorption and fluorescence properties of five rhodamine dyes in solid-state are measured and show large difference from that in their gas phase or liquid solvents. All solid-state rhodamine dyes strongly absorb all light in UV and visible region, but emit only red and NIR fluorescence (680–800 nm, >100 nm red-shifted from that in solution). Further more, the absorption maxima of a solid-state rhodamine show a large red-shifted band (~100 nm) and blue-shifted peak (~125 nm) compared to that in solutions, indicating a strong molecular exciton coupling between molecules. All solid-state rhodamines still show reasonably good fluorescence quantum yield (Φ{sub f}). In particular, solid-state Rhodamine B butyl ester and sulfonyl Rhodamine B showed a much longer emission lifetime (τ{sub f}) than that of the corresponding molecular rhodamine, i.e. 4.12 and 4.14 ns in solid state compared to 1.61 and 2.47 ns in solution. The chemical structure of a rhodamine molecule showed dramatic effect on Φ{sub f} and τ{sub f} values for solid state rhodamine. The larger substituent in the benzene moiety favors higher Φ{sub f} and τ{sub f} values of rhodamine solids. These effects can be elucidated by the relation between structure-molecular distance and molecular exciton couplings. - Highlights: • Optical properties of solid rhodamines show large difference from that in solutions. • Solid-state rhodamine dyes emit red and NIR fluorescence (680–800 nm). • Solid-state rhodamines still show reasonably good fluorescence quantum yield. • Solid-state rhodamines have much longer fluorescence lifetimes than that in solutions.

Table-top instrumentation for time-resolved luminescence spectroscopy of solids excited by nanosecond pulse of soft X-ray source and/or UV laser

International Nuclear Information System (INIS)

Bruza, Petr; Fidler, Vlastimil; Nikl, Martin

2011-01-01

The practical applicability of the rare-earth doped scintillators in high-speed detectors is limited by the slow decay components in the temporal response of a scintillator. The study of origin and properties of material defects that induce the slow decay components is of major importance for the development of new scintillation materials. We present a table-top, time-domain UV-VIS luminescence spectrometer, featuring extended time and input sensitivity ranges and two excitation sources. The combination of both soft X-ray/XUV and UV excitation source allows the comparative measurements of luminescence spectra and decay kinetics of scintillators to be performed under the same experimental conditions. The luminescence of emission centers of a doped scintillator can be induced by conventional N 2 laser pulse, while the complete scintillation process can be initiated by a soft X-ray/XUV pulse excitation from the laser-produced plasma in gas puff target of 4 ns duration. In order to demonstrate the spectrometer, the UV-VIS luminescence spectra and decay kinetics of cerium doped Lu 3 Al 5 O 12 single crystal (LuAG:Ce) scintillator excited by XUV and UV radiation were acquired. Luminescence of the doped Ce 3+ ions was studied under 2.88 nm (430 eV) XUV excitation from the laser-produced nitrogen plasma, and compared with the luminescence under 337 nm (3.68 eV) UV excitation from nitrogen laser. In the former case the excitation energy is deposited in the LuAG host, while in the latter the 4f-5d 2 transition of Ce 3+ is directly excited. Furthermore, YAG:Ce and LuAG:Ce single crystals luminescence decay profiles are compared and discussed.

Thermodynamic Modeling of Poorly Complexing Metals in Concentrated Electrolyte Solutions: An X-Ray Absorption and UV-Vis Spectroscopic Study of Ni(II) in the NiCl2-MgCl2-H2O System

Science.gov (United States)

Zhang, Ning; Brugger, Joël; Etschmann, Barbara; Ngothai, Yung; Zeng, Dewen

2015-01-01

Knowledge of the structure and speciation of aqueous Ni(II)-chloride complexes is important for understanding Ni behavior in hydrometallurgical extraction. The effect of concentration on the first-shell structure of Ni(II) in aqueous NiCl2 and NiCl2-MgCl2 solutions was investigated by Ni K edge X-ray absorption (XAS) and UV-Vis spectroscopy at ambient conditions. Both techniques show that no large structural change (e.g., transition from octahedral to tetrahedral-like configuration) occurs. Both methods confirm that the Ni(II) aqua ion (with six coordinated water molecules at R Ni-O = 2.07(2) Å) is the dominant species over the whole NiCl2 concentration range. However, XANES, EXAFS and UV-Vis data show subtle changes at high salinity (> 2 mol∙kg-1 NiCl2), which are consistent with the formation of small amounts of the NiCl+ complex (up to 0.44(23) Cl at a Ni-Cl distance of 2.35(2) Å in 5.05 mol∙kg-1 NiCl2) in the pure NiCl2 solutions. At high Cl:Ni ratio in the NiCl2-MgCl2-H2O solutions, small amounts of [NiCl2]0 are also present. We developed a speciation-based mixed-solvent electrolyte (MSE) model to describe activity-composition relationships in NiCl2-MgCl2-H2O solutions, and at the same time predict Ni(II) speciation that is consistent with our XAS and UV-Vis data and with existing literature data up to the solubility limit, resolving a long-standing uncertainty about the role of chloride complexing in this system. PMID:25885410

Characterization of solid UV cross-linked PEGDA for biological applications

KAUST Repository

Castro, David

2013-10-20

This paper reports on solid UV cross-linked Poly(ethylene)-glycol-diacrylate (PEGDA) as a material for microfluidic devices for biological applications. We have evaluated biocompatibility of PEGDA through two separate means: 1) by examining cell viability and attachment on cross-linked PEGDA surfaces for cell culture applications, and 2) by determining if cross-linked PEGDA inhibits the polymerase chain reaction (PCR) processes for on-chip PCR. Through these studies a correlation has been found between degree of curing and cell viability, attachment, as well as on PCR outcome.

Solid state chemistry an introduction

CERN Document Server

Smart, Lesley E

2012-01-01

""Smart and Moore are engaging writers, providing clear explanations for concepts in solid-state chemistry from the atomic/molecular perspective. The fourth edition is a welcome addition to my bookshelves. … What I like most about Solid State Chemistry is that it gives simple clear descriptions for a large number of interesting materials and correspondingly clear explanations of their applications. Solid State Chemistry could be used for a solid state textbook at the third or fourth year undergraduate level, especially for chemistry programs. It is also a useful resource for beginning graduate

UV absorption by cerium oxide nanoparticles/epoxy composite thin films

International Nuclear Information System (INIS)

Dao, Ngoc Nhiem; Luu, Minh Dai; Nguyen, Quang Khuyen; Kim, Byung Sun

2011-01-01

Cerium oxide (CeO 2 ) nanoparticles have been used to modify properties of an epoxy matrix in order to improve the ultra-violet (UV) absorption property of epoxy thin films. The interdependence of mechanical properties, UV absorption property and the dispersed concentration of CeO 2 nanoparticles was investigated. Results showed that, by increasing the dispersed concentration of CeO 2 nanoparticles up to 3 wt%, tensile modulus increases while two other mechanical properties, namely tensile strength and elongation, decrease. The UV absorption peak and the absorption edges of the studied thin films were observed in the UV-Vis absorption spectra. By incorporating CeO 2 nanoparticles into the epoxy matrix, an absorption peak appears at around 318 nm in UV-Vis spectra with increasing CeO 2 concentration from 0.1 to 1.0 wt%. Scanning electron microscopy (SEM) images revealed that a good dispersion of nanoparticles in the epoxy matrix by an ultrasonic method was achieved

The solid state maser

CERN Document Server

Orton, J W; Walling, J C; Ter Haar, D

1970-01-01

The Solid State Maser presents readings related to solid state maser amplifier from the first tentative theoretical proposals that appeared in the early 1950s to the successful realization of practical devices and their application to satellite communications and radio astronomy almost exactly 10 years later. The book discusses a historical account of the early developments (including that of the ammonia maser) of solid state maser; the properties of paramagnetic ions in crystals; the development of practical low noise amplifiers; and the characteristics of maser devices designed for communica

Solid state chemistry and its applications

CERN Document Server

West, Anthony R

2013-01-01

Solid State Chemistry and its Applications, 2nd Edition: Student Edition is an extensive update and sequel to the bestselling textbook Basic Solid State Chemistry, the classic text for undergraduate teaching in solid state chemistry worldwide. Solid state chemistry lies at the heart of many significant scientific advances from recent decades, including the discovery of high-temperature superconductors, new forms of carbon and countless other developments in the synthesis, characterisation and applications of inorganic materials. Looking forward, solid state chemistry will be crucial for the

Photocatalytic reductive dechlorination of 2-chlorodibenzo-p-dioxin by Pd modified g-C3N4 photocatalysts under UV-vis irradiation: Efficacy, kinetics and mechanism.

Science.gov (United States)

Ding, Jiafeng; Long, Gaoyuan; Luo, Yang; Sun, Runze; Chen, Mengxia; Li, Yajun; Zhou, Yanfang; Xu, Xinhua; Zhao, Weirong

2018-05-09

Polychlorinated dibenzo-p-dioxins (PCDDs), as a group of notorious anthropogenic environmental toxicants, are arguably ubiquitous in nature. In this study, we investigated the photocatalytic reductive dechlorination of 2-chlorodibenzo-p-dioxin (2-CDD) over Pd/g-C 3 N 4 catalysts under UV-vis irradiation. The g-C 3 N 4 and a series of Pd/g-C 3 N 4 catalysts were prepared by thermal polymerization and mechanical mixing-illumination method and characterized by XRD, TEM, BET, SEM and UV-vis DRS analyses. Among all the samples, the Pd/g-C 3 N 4 (5 wt%) yielded the optimal dechlorination activity with a total 2-CDD conversion of 54% within 4 h, and 76% of those converted 2-CDD were evolved to dibenzo-p-dioxin (DD). The kinetics of dechlorination could be described as pseudo-first-order decay model (R 2  > 0.84). Corresponding rate constants (k) increased from 0.052 to 0.17 h -1 with Pd contents up to 5 wt% and decreased to 0.13 h -1 with a 10 wt% of Pd. The enhanced activities originated from the surface plasmonic resonance (SPR) effect of Pd nanoparticles and the formation of Schottky barrier between Pd and g-C 3 N 4 , which extend the spectrum responsive range and suppress the charge recombination of g-C 3 N 4 . This is the first report on the photocatalytic reductive removal of PCDDs and may provide a new approach for PCDDs pollution control. Copyright © 2018 Elsevier B.V. All rights reserved.

Study on coordination characteristics of neptunium and uranium ions in calcium nitrate hydrate melt by Raman spectrometry and UV/Vis/NIR spectrometry

International Nuclear Information System (INIS)

Fujii, T; Okude, G; Uehara, A; Yamana, H

2010-01-01

Extraction behavior of neptunium (Np) by tri-n-butyl phosphate from calcium nitrate hydrate melt was investigated. Distribution ratio of Np was found to increase with the decrease of water content. Adding nitric acid into the system resulted in an increase of the distribution ratio. In order to understand the extraction trends, Np species in the hydrate melt were analyzed by Raman spectrometry and UV/Vis/NIR spectrometry. Major fraction was assigned to be NpO 2 2+ of Np(VI) and small fraction to be NpO 2 + of Np(V). A shift of the v 1 symmetric vibrational frequency of NpO 2 2+ in nitrate media was found in Raman spectra. This suggests a coordination circumstance change of NpO 2 2+ .

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

New biphenyl derivatives of bis-imidazoline selones were synthesized in good yield and characterized by multinuclear (1D and 2D) NMR and UV-vis studies. The solid state structures of bis-imidazoline selones were further confirmed by single crystal X ray diffraction technique.

Theoretical Calculation of the Uv-Vis Spectral Band Locations of Pahs with Unknown Syntheses Procedures and Prospective Carcinogenic Activity

Science.gov (United States)

Ona-Ruales, Jorge Oswaldo; Ruiz-Morales, Yosadara

2017-06-01

Annellation Theory and ZINDO/S semiempirical calculations have been used for the calculation of the locations of maximum absorbance (LMA) of the Ultraviolet-Visible (UV-Vis) of 31 C_{34}H_{16} PAHs (molecular mass 424 Da) with unknown protocols of synthesis. The presence of benzo[a]pyrene bay-like regions and dibenzo[a,l]pyrene fjord-like regions in several of the structures that could be linked to an enhancement of the biological behavior and carcinogenic activity stresses the importance of C_{34}H_{16} PAHs in fields like molecular biology and cancer research. In addition, the occurrence of large PAHs in oil asphaltenes exemplifies the importance of these calculations for the characterization of complex systems. The C_{34}H_{16} PAH group is the largest molecular mass group of organic compounds analyzed so far following the Annellation Theory and ZINDO/S methodology. Future analysis using the same approach will provide evidence regarding the LMA of other high molecular mass PAHs.

An insight into the complexation of trivalent americium vis-a-vis lanthanides with bis(1,2,4-triazinyl)bipyridine derivatives

Energy Technology Data Exchange (ETDEWEB)

Bhattacharyya, Arunasis; Mohapatra, Manoj; Mohapatra, Prasanta K. [Bhabha Atomic Research Centre, Trombay, Mumbai (India). Radiochemistry Div.; Gadly, Trilochan; Ghosh, Sunil K. [Bhabha Atomic Research Centre, Trombay, Mumbai (India). Bioorganic Div.; Manna, Debashree; Ghanty, Tapan K. [Bhabha Atomic Research Centre, Trombay, Mumbai (India). Theoretical Chemistry Section; Rawat, Neetika; Tomar, Bhupendra S. [Bhabha Atomic Research Centre, Trombay, Mumbai (India). Radioanalytical Chemistry Div.

2017-01-26

Complexation of Am{sup 3+} and Ln{sup 3+} (La{sup 3+}, Eu{sup 3+}, and Er{sup 3+}) with two bis(1,2,4-triazinyl)bipyridine (C{sub 2}BTBP, C{sub 5}BTBP) derivatives has been studied in acetonitrile medium with use of various experimental techniques such as electrospray ionization mass spectrometry (ESI-MS), time-resolved fluorescence spectroscopy (TRFS), UV/Vis spectrophotometry, and solution calorimetry. Metal-ligand stoichiometries and conditional stability constants of these complexes were determined. To the best of our knowledge, this is the first report on the complexation of Am{sup 3+} with any of the BTBP derivatives with use of UV/Vis spectrophotometric titration to determine the conditional stability constants. Density functional theory (DFT) calculations are carried out on the An{sup 3+} (U{sup 3+} and Am{sup 3+}) and Ln{sup 3+} (La{sup 3+}, Nd{sup 3+}, Eu{sup 3+}, Er{sup 3+}, and Lu{sup 3+}) complexes of BTBP in order to understand the difference between the bonding in actinide and lanthanide complexes. The results indicate a stronger covalent interaction in the An-N bonds as compared to the Ln-N bonds, which leads to an actinide selectivity of this class of ligands. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Development of UV absorbing PET through Electron Irradiation

International Nuclear Information System (INIS)

Kim, Jung Woo; Lee, Na Eun; Lim, Hyung San; Park, Yang Jeong; Cho, Sung Oh

2017-01-01

Experiment to increase UV absorbance through electron beam irradiation on PET was performed. Moreover, surface hardness and roughness of each sample were observed to find the key factor increasing UV absorbance. PET sheets were irradiated with an electron beam at various fluences. The irradiated samples, as well as pristine sample, were subjected to UV-visible spectral study(UV-Vis), pencil hardness test, and scanning electron microscopy(SEM) experiment. In this study, PET samples irradiated at several conditions were analyzed through various measurements. UV absorbance-another meaning of transmittance in this study- of irradiated PET sample increased compared with pristine sample as fluence was increased in UV-Visible spectroscopy experiment.

Einstein and solid-state physics

International Nuclear Information System (INIS)

Aut, I.

1982-01-01

A connection between the development of solid-state physics and the works and activity of Albert Einstein is traced. A tremendous Einstein contribution to solid state physics is marked. A strict establishment of particle-wave dualism; a conclusion about the applicability of the Plank radiation law not only to black body radiation; finding out particles indistinguishability - all three discoveries have a principle significance for solid state physics too

Controlled UV-C light-induced fusion of thiol-passivated gold nanoparticles.

Science.gov (United States)

Pocoví-Martínez, Salvador; Parreño-Romero, Miriam; Agouram, Said; Pérez-Prieto, Julia

2011-05-03

Thiol-passivated gold nanoparticles (AuNPs) of a relatively small size, either decorated with chromophoric groups, such as a phthalimide (Au@PH) and benzophenone (Au@BP), or capped with octadecanethiol (Au@ODCN) have been synthesized and characterized by NMR and UV-vis spectroscopy as well as transmission electron microscopy (TEM). These NPs were irradiated in chloroform at different UV-wavelengths using either a nanosecond laser (266 and 355 nm, ca. 12 mJ/pulse, 10 ns pulse) or conventional lamps (300 nm UV-vis spectroscopy, as well as by TEM. Laser irradiation at 355 nm led to NP aggregation and precipitation, while the NPs were photostable under UV-A lamp illumination. Remarkably, laser excitation at 266 nm induced a fast (minutes time-scale) increase in the size of the NPs, producing huge spherical nanocrystals, while lamp-irradiation at UV-C wavelengths brought about nanonetworks of partially fused NPs with a larger diameter than the native NPs.

Excited-state intramolecular hydrogen transfer (ESIHT) of 1,8-Dihydroxy-9,10-anthraquinone (DHAQ) characterized by ultrafast electronic and vibrational spectroscopy and computational modeling

KAUST Repository

Mohammed, Omar F.; Xiao, Dequan; Batista, Victor S.; Nibbering, Erik Theodorus Johannes

2014-01-01

of femtosecond UV/vis and UV/IR pump-probe spectroscopic data. Upon photoabsorption at 400 nm, the S 2 electronic excited state is initially populated, followed by a rapid equilibration within 150 fs through population transfer to the S 1 state where DHAQ

Solid-state circuits

CERN Document Server

Pridham, G J

2013-01-01

Solid-State Circuits provides an introduction to the theory and practice underlying solid-state circuits, laying particular emphasis on field effect transistors and integrated circuits. Topics range from construction and characteristics of semiconductor devices to rectification and power supplies, low-frequency amplifiers, sine- and square-wave oscillators, and high-frequency effects and circuits. Black-box equivalent circuits of bipolar transistors, physical equivalent circuits of bipolar transistors, and equivalent circuits of field effect transistors are also covered. This volume is divided

Feasibility of UV-VIS-Fluorescence spectroscopy combined with pattern recognition techniques to authenticate a new category of plant food supplements.

Science.gov (United States)

Boggia, Raffaella; Turrini, Federica; Anselmo, Marco; Zunin, Paola; Donno, Dario; Beccaro, Gabriele L

2017-07-01

Bud extracts, named also "gemmoderivatives", are a new category of natural products, obtained macerating meristematic fresh tissues of trees and plants. In the European Community these botanical remedies are classified as plant food supplements. Nowadays these products are still poorly studied, even if they are widely used and commercialized. Several analytical tools for the quality control of these very expensive supplements are urgently needed in order to avoid mislabelling and frauds. In fact, besides the usual quality controls common to the other botanical dietary supplements, these extracts should be checked in order to quickly detect if the cheaper adult parts of the plants are deceptively used in place of the corresponding buds whose harvest-period and production are extremely limited. This study aims to provide a screening analytical method based on UV-VIS-Fluorescence spectroscopy coupled to multivariate analysis for a rapid, inexpensive and non-destructive quality control of these products.

Influence of UV-Irradiation on Latent Tracks in Polyethylene Terephthalate Films

International Nuclear Information System (INIS)

Wen Qi; Wang Peng-Fei; Ling Yun; Wang Mao; Yan Dong-Xiao; Wang Yu-Gang; Cao Xing-Zhong; Wang Bao-Yi

2016-01-01

Polyethylene terephthalate (PET) films in thickness of 12 μm are irradiated by Xe and Au ions at the energies of 9.5 and 11.4MeV/u and with the ion fluence from 5 × 10"9 cm"−"2 to 1 × 10"1"1 cm"−"2. After irradiation, ultra-violet lights are used to illuminate the samples with latent tracks at the wavelength of 365 nm with flux density of 4.2 mW/cm"−"2. UV-irradiation effects on tracked PET are investigated by the UV-vis spectrum and positron annihilation lifetime spectroscopy (PALS). It is found that carbonaceous clusters in PET films are generated by ion irradiation and decomposed with UV illumination by calculating the optical energy band gap E_g in the UV-vis spectrum. The free volumes behave differently in track and bulk after UV illumination. In our experiment, the PALS results show an increase in radius and density of free volume in tracked PET films after UV treatment, which indicates an expansion in radius of latent tracks. (paper)

Monitoring changes in the structure and properties of humic substances following ozonation using UV-Vis, FTIR and (1)H NMR techniques.

Science.gov (United States)

Rodríguez, Francisco J; Schlenger, Patrick; García-Valverde, María

2016-01-15

The main objective of this work is to conduct a comprehensive structural characterization of humic substances using the following experimental techniques: FTIR, 1H NMR and several UV–Vis parameters (Specific UV Absorbance at 254 nm or SUVA254, SUVA280, A400, the absorbance ratios A210/254, A250/365, A254/203, A254/436, A265/465, A270/400, A280/350, A465/665, the Absorbance Slope Index (ASI), the spectral slopes S275–295, S350–400 and the slope ratio SR). These UV–Vis parameters have also been correlated with key properties of humic substances such as aromaticity, molecular weight (MW) and trihalomethane formation potential (THMFP). An additional objective of this work is also to evaluate the usefulness of these techniques to monitor structural changes in humic substances produced by the ozonation treatment. Four humic substances were studied in this work: three of them were provided by the International Humic Substances Society (Suwannee River Fulvic Acid Standard: SRFA, Suwannee River Humic Acid Standard: SRHA and Nordic Reservoir Fulvic Acid Reference: NLFA) and the other one was a terrestrial humic acid widely used as a surrogate for aquatic humic substances in various studies (Aldrich Humic Acid: AHA). The UV–Vis parameters showing the best correlations with aromaticity in this study were SUVA254, SUVA280, A280/A350 ratio and A250/A364 ratio. The best correlations with molecular weight were for SUVA254, SUVA280 and A280/A350 ratio. Finally, in the case of the THMFP it was STHMFP-per mol HS the parameter showing good correlations with most of the UV–Vis parameters studied (especially with A280/A350 ratio, A265/A465 ratio and A270/A400 ratio) whereas STHMFP-per mg C showed poor correlations in most cases. On the whole, the UV–Vis parameter showing the best results was A280/A350 ratio as it showed excellent correlations for the three properties studied (aromaticity, MW and THMFP). A decrease in aromaticity following ozonation of humic substances can

Enhancement of UV absorption behavior in Zn O-TiO2 composites

International Nuclear Information System (INIS)

Jimenez Reinosa, J.; Leret, P.; Alvarez-Docio, C. M.; Campo, A. del; Fernandez, J. F.

2016-01-01

The ultraviolet -visible, UV-vis, absorption edge behaviour of semiconductor oxides as TiO 2 and ZnO promotes their use as inorganic UV filters for sunscreens. In cosmetics, the use of nanoparticles is favoured because of their higher yield and lower whiteness. However, the particle size effect in the UV absorption is unclear. For this reason, the performances of nano and microsized TiO 2 and ZnO are evaluated in both the UV-vis spectroscopy and the Sun Protection Factor, SPF, value. In order to cover the UV range completely by using inorganic filters a new composite is attempted by dry nano dispersion methodology in which TiO 2 nanoparticles are dispersed onto ZnO microparticles. The new composite shows superior UV absorbing properties and ca. 60% SPF value due to a synergism between components that resulted in extended UV coverage and reduction of the total amount of nanoparticles required in the sunscreens. In addition, nanoparticles are effectively anchored onto microparticles avoiding the presence of free nanoparticles. (Author)

Persistence of oxidation state III of gold in thione coordination

Science.gov (United States)

Jääskeläinen, Sirpa; Koskinen, Laura; Kultamaa, Matti; Haukka, Matti; Hirva, Pipsa

2017-05-01

Ligands N,N'-tetramethylthiourea and 2-mercapto-1-methyl-imidazole form stable Au(III) complexes [AuCl3(N,N'-tetramethylthiourea)] (1) and [AuCl3(2-mercapto-1-methyl-imidazole)] (2) instead of reducing the Au(III) metal center into Au(I), which would be typical for the attachment of sulfur donors. Compounds 1 and 2 were characterized by spectroscopic methods and by X-ray crystallography. The spectroscopic details were explained by simulation of the UV-Vis spectra via the TD-DFT method. Additionally, computational DFT studies were performed in order to find the reason for the unusual oxidation state in the crystalline materials. The preference for Au(III) can be explained via various weak intra- and intermolecular interactions present in the solid state structures. The nature of the interactions was further investigated by topological charge density analysis via the QTAIM method.

Q-mode curve resolution of UV-vis spectra for structural transformation studies of anthocyanins in acidic solutions

International Nuclear Information System (INIS)

Marco, Paulo Henrique; Scarminio, Ieda Spacino

2007-01-01

Chemometric analysis of ultraviolet-visible (UV-vis) spectra for pH values 1.0, 3.3, 5.3, and 6.9 was used to investigate the kinetics and the structural transformations of anthocyanins in extracts of calyces of hibiscus flowers of the Hibiscus acetosella Welw. ex Finicius for the first time. Six different species were detected: the quinoidal base (A), the flavylium cation (AH + ), the pseudobase or carbinol pseudobase (B), cis-chalcone (C C ), trans-chalcone (C t ), and ionized cis-chalcone (C C - ). Four equilibrium constant values were calculated using relative concentrations, hydration, pK h =2.60+/-0.01, tautomeric, K T =0.14+/-0.01, acid-base, pK a =4.24+/-0.04, and ionization of the cis-chalcone, pK C C =8.74+/-1.5x10 -2 . The calculated protonation rate of the tautomers is K H + =0.08+/-7.6x10 -3 . These constants are in excellent agreement with those measured previously in salt form. From a kinetic viewpoint, the situation encountered is interesting since the reported investigation is limited to visible light absorption in acid medium. These models have not been reported in the literature

Cross-Linked Solid Polymer Electrolyte for All-Solid-State Rechargeable Lithium Batteries

International Nuclear Information System (INIS)

Ben youcef, Hicham; Garcia-Calvo, Oihane; Lago, Nerea; Devaraj, Shanmukaraj; Armand, Michel

2016-01-01

Semi-interpenetrated network Solid Polymer Electrolytes (SPEs) were fabricated by UV-induced cross-linking of poly(ethyleneglycol) diacrylate (PEGDA) and divinylbenzene (DVB) within a poly(ethyleneoxide) (PEO) matrix (M v = 5 × 10 6 g mol −1 ), comprising lithium bis(trifluoromethanesulfonyl)imide salt (LiTFSI), at a molar ratio of EO:Li ∼ 30:1. The influence of the DVB content on the final SPE properties was investigated in detail. An increase of DVB concentration resulted in self-standing polymer electrolytes. The DVB cross-linker incorporation was found to decrease the crystallinity of the PEO matrix from 34% to 23%, with a decrease in the melting temperature (T m ) of the membrane from 50 °C to 34 °C. Moreover, the influence of the DVB concentration on the ionic conductivity was determined for polymer electrolytes with 0, 10, 20 and 45% DVB from room temperature (RT) to 80 °C. The resulting SPEs showed a high electrochemical stability of 4.3 V as well as practical conductivity values exceeding 10 −4 S cm −1 at 70 °C. Cycling performance of these semi-interpenetrated SPE’s have been shown with a Li metal polymer battery and all solid -state Li sulphur battery.

New materials for solid state electrochemistry

International Nuclear Information System (INIS)

Ferloni, P.; Consiglio Nazionale delle Ricerche, Pavia; Magistris, A.; Consiglio Nazionale delle Ricerche, Pavia

1994-01-01

Solid state electrochemistry is an interdisciplinary area, undergoing nowadays a fast development. It is related on the one hand to chemistry, and on the other hand to crystallography, solid state physics and materials science. In this paper structural and electrical properties of some families of new materials interesting for solid state electrochemistry are reviewed. Attention is focused essentially on ceramic and crystalline materials, glasses and polymers, displaying high ionic conductivity and potentially suitable for various applications in solid state electrochemical devices. (orig.)

Low-temperature solid-state synthesis and optical properties of CdS-ZnS and ZnS-CdS alloy nanoparticles

International Nuclear Information System (INIS)

Liu Jinsong; Zhao Chuanbao; Li Ziquan; Chen Jiankang; Zhou Hengzhi; Gu Shanqun; Zeng Youhong; Li Yongchan; Huang Yongbing

2011-01-01

Highlights: → Using a simple low-temperature solid-state synthetic method, ZnS-CdS and CdS-ZnS alloy nanoparticles were obtained, respectively. → The size of the nanoparticles increased with increasing reaction temperature, and reaction sequence had no effect on the size of the nanoparticles under the same temperature. → The particle diameters of the CdS-ZnS products decreased gradually with increasing Cd 2+ /Zn 2+ molar ratio, whereas those of the ZnS-CdS products increased gradually with increasing Zn 2+ /Cd 2+ molar ratio. → The study shows that sufficient grinding and crystalline water may be a key in forming the alloy nanoparticles. → Optical properties of the products depend on reaction temperature, reactant addition sequence, and reactant molar ratio. - Abstract: A simple low-temperature solid-state synthetic method was employed to obtain ZnS-CdS and CdS-ZnS alloy nanoparticles. The effects of reaction sequence, reactant molar ratios, and synthesis temperature on the products were investigated. The crystal structure and morphology of the products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and fourier transform infrared (FT-IR) spectroscopy. The results show that the products are alloy nanoparticles with a cubic phase structure. The formation mechanism of the alloy nanoparticles is briefly discussed. Sufficient grinding and crystalline water may be essential to form alloy nanoparticles. Ultraviolet-visible (UV-vis) spectra show that the edge absorptions of the CdS-ZnS and ZnS-CdS nanoparticles were located between those of ZnS and CdS bulks, and the absorbance at the peak maximum was practically dependent on reaction temperature, reaction sequence, and molar ratio. Extrinsic deep-level emission resulted in strong peaks in the photoluminescence (PL) spectra. The position and intensity of the emission peaks varied with the conditions during synthesis.

Theoretical solid state physics

International Nuclear Information System (INIS)

Anon.

1977-01-01

Research activities at ORNL in theoretical solid state physics are described. Topics covered include: surface studies; particle-solid interactions; electronic and magnetic properties; and lattice dynamics

Solid-State Physics Introduction to the Theory

CERN Document Server

Patterson, James

2010-01-01

Learning Solid State Physics involves a certain degree of maturity, since it involves tying together diverse concepts from many areas of physics. The objective is to understand, in a basic way, how solid materials behave. To do this one needs both a good physical and mathematical background. One definition of Solid State Physics is it is the study of the physical (e.g. the electrical, dielectric, magnetic, elastic, and thermal) properties of solids in terms of basic physical laws. In one sense, Solid State Physics is more like chemistry than some other branches of physics because it focuses on common properties of large classes of materials. It is typical that Solid State Physics emphasizes how physics properties link to electronic structure. We have retained the term Solid Modern solid state physics came of age in the late thirties and forties and is now is part of condensed matter physics which includes liquids, soft materials, and non-crystalline solids. This solid state/condensed matter physics book begin...

Insights into the Activity and Deactivation of the Methanol-to-Olefins Process over Different Small-Pore Zeolites As Studied with Operando UV-vis Spectroscopy.

Science.gov (United States)

Goetze, Joris; Meirer, Florian; Yarulina, Irina; Gascon, Jorge; Kapteijn, Freek; Ruiz-Martínez, Javier; Weckhuysen, Bert M

2017-06-02

The nature and evolution of the hydrocarbon pool (HP) species during the Methanol-to-Olefins (MTO) process for three small-pore zeolite catalysts, with a different framework consisting of large cages interconnected by small eight-ring windows (CHA, DDR, and LEV) was studied at reaction temperatures between 350 and 450 °C using a combination of operando UV-vis spectroscopy and online gas chromatography. It was found that small differences in cage size, shape, and pore structure of the zeolite frameworks result in the generation of different hydrocarbon pool species. More specifically, it was found that the large cage of CHA results in the formation of a wide variety of hydrocarbon pool species, mostly alkylated benzenes and naphthalenes. In the DDR cage, 1-methylnaphthalene is preferentially formed, while the small LEV cage generally contains fewer hydrocarbon pool species. The nature and evolution of these hydrocarbon pool species was linked with the stage of the reaction using a multivariate analysis of the operando UV-vis spectra. In the 3-D pore network of CHA, the reaction temperature has only a minor effect on the performance of the MTO catalyst. However, for the 2-D pore networks of DDR and LEV, an increase in the applied reaction temperature resulted in a dramatic increase in catalytic activity. For all zeolites in this study, the role of the hydrocarbon species changes with reaction temperature. This effect is most clear in DDR, in which diamantane and 1-methylnaphthalene are deactivating species at a reaction temperature of 350 °C, whereas at higher temperatures diamantane formation is not observed and 1-methylnaphthalene is an active species. This results in a different amount and nature of coke species in the deactivated catalyst, depending on zeolite framework and reaction temperature.

Solvatochromism and preferential solvation of 1,4-dihydroxy-2,3-dimethyl-9,10-anthraquinone by UV-vis absorption and laser-induced fluorescence measurements

Science.gov (United States)

Sasirekha, V.; Vanelle, P.; Terme, T.; Ramakrishnan, V.

2008-12-01

Solvation characteristics of 1,4-dihydroxy-2,3-dimethyl-9,10-anthraquinone ( 1) in pure and binary solvent mixtures have been studied by UV-vis absorption spectroscopy and laser-induced fluorescence techniques. The binary solvent mixtures used as CCl 4 (tetrachloromethane)-DMF ( N, N-dimethylformamide), AN (acetonitrile)-DMSO (dimethylsulfoxide), CHCl 3 (chloroform)-DMSO, CHCl 3-MeOH (methanol), and MeOH-DMSO. The longest wavelength band of 1 has been studied in pure solvents as well as in binary solvent mixtures as a function of the bulk mole fraction. The Vis absorption band maxima show an unusual blue shift with increasing solvent polarity. The emission maxima of 1 show changes with varying the pure solvents and the composition in the case of binary solvent mixtures. Non-ideal solvation characteristics are observed in all binary solvent mixtures. It has been observed that the quantity [ ν-(Xν+Xν)] serves as a measure of the extent of preferential solvation, where ν˜ and X are the position of band maximum in wavenumbers (cm -1) and the bulk mole fraction values, respectively. The preferential solvation parameters local mole fraction ( X2L), solvation index ( δs2), and exchange constant ( k12) are evaluated.

Photocatalytic properties of Au-deposited mesoporous SiO_2–TiO_2 photocatalyst under simultaneous irradiation of UV and visible light

International Nuclear Information System (INIS)

Okuno, T.; Kawamura, G.; Muto, H.; Matsuda, A.

2016-01-01

Mesoporous SiO_2 templates deposited TiO_2 nanocrystals are synthesized via a sol–gel route, and Au nanoparticles (NPs) are deposited in the tubular mesopores of the templates by a photodeposition method (Au/SiO_2–TiO_2). The photocatalytic characteristics of Au/SiO_2–TiO_2 are discussed with the action spectra of photoreactions of 2-propanol and methylene blue. Photocatalytic activities of SiO_2–TiO_2 under individual ultraviolet (UV) and visible (Vis) light illumination are enhanced by deposition of Au NPs. Furthermore, Au/SiO_2–TiO_2 shows higher photocatalytic activities under simultaneous irradiation of UV and Vis light compared to the activity under individual UV and Vis light irradiation. Since the photocatalytic activity under simultaneous irradiation is almost the same as the total activities under individual UV and Vis light irradiation, it is concluded that the electrons and the holes generated by lights of different wavelengths are efficiently used for photocatalysis without carrier recombination. - Graphical abstract: This graphic shows the possible charge behavior in Au/SiO_2–TiO_2 under independent light irradiation of ultraviolet and visible light irradiation. Both reactions under independent UV and Vis light irradiation occurred in parallel when Au/SiO_2–TiO_2 photocatalyst was illuminated UV and Vis light simultaneously, and then photocatalytic activity is improved by simultaneous irradiation. - Highlights: • Au nanoparticles were deposited in mesoporous SiO_2–TiO_2 by a photodeposition method. • Photocatalytic activity under UV and Vis light was enhanced by deposition of Au. • Photocatalytic activity of Au/SiO_2–TiO_2 was improved by simultaneous irradiation.

Quantum Computing in Solid State Systems

CERN Document Server

Ruggiero, B; Granata, C

2006-01-01

The aim of Quantum Computation in Solid State Systems is to report on recent theoretical and experimental results on the macroscopic quantum coherence of mesoscopic systems, as well as on solid state realization of qubits and quantum gates. Particular attention has been given to coherence effects in Josephson devices. Other solid state systems, including quantum dots, optical, ion, and spin devices which exhibit macroscopic quantum coherence are also discussed. Quantum Computation in Solid State Systems discusses experimental implementation of quantum computing and information processing devices, and in particular observations of quantum behavior in several solid state systems. On the theoretical side, the complementary expertise of the contributors provides models of the various structures in connection with the problem of minimizing decoherence.

Solid state theory

CERN Document Server

Harrison, Walter A

2011-01-01

""A well-written text . . . should find a wide readership, especially among graduate students."" - Dr. J. I. Pankove, RCA.The field of solid state theory, including crystallography, semi-conductor physics, and various applications in chemistry and electrical engineering, is highly relevant to many areas of modern science and industry. Professor Harrison's well-known text offers an excellent one-year graduate course in this active and important area of research. While presenting a broad overview of the fundamental concepts and methods of solid state physics, including the basic quantum theory o

Solid-State Nanopore

Directory of Open Access Journals (Sweden)

Zhishan Yuan

2018-02-01

Full Text Available Abstract Solid-state nanopore has captured the attention of many researchers due to its characteristic of nanoscale. Now, different fabrication methods have been reported, which can be summarized into two broad categories: “top-down” etching technology and “bottom-up” shrinkage technology. Ion track etching method, mask etching method chemical solution etching method, and high-energy particle etching and shrinkage method are exhibited in this report. Besides, we also discussed applications of solid-state nanopore fabrication technology in DNA sequencing, protein detection, and energy conversion.

Luminescence characterization of sol-gel derived Pr"3"+ doped NaGd(WO_4)_2 phosphors for solid state lighting applications

International Nuclear Information System (INIS)

Durairajan, A.; Thangaraju, D.; Moorthy Babu, S.; Valente, M.A.

2016-01-01

In the present work, xPr"3"+:NaGd(WO_4)_2 (0.5 ≤ x ≤ 5.0 mol%) sub-micron phosphors were synthesised by sol-gel method. Low cost precursors of metal nitrates and low temperature thermal treatment was used compared to conventional solid state reaction. The formation of highly crystalline phosphors with tetragonal structure was confirmed by XRD and increase of Pr"3"+ ions content in host matrix leads to expansion of the unit cell volume. The surface morphology, size and particle distribution of the phosphors were observed by field emission scanning electron microscopy (FE-SEM). A rectangular shape particle with a size distribution ranging from 400 to 600 nm and tightly packed surface was seen in FE-SEM micrographs. The various internal and external phonon modes vibration corresponding to double tungstate structure was observed in Raman spectra. The optical properties of the synthesised phosphors were explored by ultraviolet visible (UV–Vis) absorption in diffuse reflectance and photoluminescence (PL) measurements. UV–Vis measurements distinguished the host and Pr"3"+ absorption and also reveal an increase in optical band gap values with an increase of Pr"3"+. The PL measurements show various emissions from green and red regions under 450 nm. The maximum intensity emission at 489 nm is due to "3P_0 → "3H_4 transition of Pr"3"+. From the maximum emission the critical doping concentration was calculated to be at 3.5 mol% and critical distance between two adjacent Pr"3"+ ions as 20.43 Å. - Highlights: • A sol-gel method was used to prepare Pr"3"+ doped NaGd(WO_4)_2 at low temperature. • Structural, spectroscopic, morphological, and optical and luminescence properties were studied. • The praseodymium ions are in trivalent state, the site symmetry is distorted and S_4 local symmetry with Na"+ ions. • Strong green emission was observed under UV and visible excitation.

Solid State Physics Introduction to the Theory

CERN Document Server

Patterson, James D

2007-01-01

Learning Solid State Physics involves a certain degree of maturity, since it involves tying together diverse concepts from many areas of physics. The objective is to understand, in a basic way, how solid materials behave. To do this one needs both a good physical and mathematical background. One definition of Solid State Physics is it is the study of the physical (e.g. the electrical, dielectric, magnetic, elastic, and thermal) properties of solids in terms of basic physical laws. In one sense, Solid State Physics is more like chemistry than some other branches of physics because it focuses on common properties of large classes of materials. It is typical that Solid State Physics emphasizes how physics properties link to electronic structure. We have retained the term Solid State Physics, even though Condensed Matter Physics is more commonly used. Condensed Matter Physics includes liquids and non-crystalline solids such as glass, which we shall not discuss in detail. Modern Solid State Physics came of age in ...

Synthesis and photoluminescence properties of LiSrPO{sub 4}:Eu{sup 2+} phosphor for solid state lighting

Energy Technology Data Exchange (ETDEWEB)

Game, D. N., E-mail: deorao.game@gmail.com [Deccan Education Society’s Technical Institute, Fergusson College Campus, Pune (India); Taide, S. T.; Khan, Z. S.; Omanwar, S. K. [Department of Physics, Sant Gadge Baba, Aravati University, Amravati (India); Ingale, N. B. [Prof. Ram Meghe Institute of Technology and Research, Badnera, Amravati (India)

2016-05-06

A novel method to prepare orthophosphate LiSrPO{sub 4}: Eu{sup 2+} phosphor for white light-emitting diodes (w-LEDs) is given in this paper. Phosphor was successfully synthesized by Pechini (citrate gel) method which is efficient than conventional high temperature solid state reaction. X-ray powder diffraction (XRD) analysis confirmed the single phase formation of LiSrPO{sub 4}:Eu{sup 2+} with monoclinic crystal structure. Luminescence results showed that the phosphor could be efficiently excited by near UV and exhibited bright blue emission at λ{sub em} = 420 nm corresponding to 5d– 4f transition of Eu{sup 2+}. The phosphor exhibits blue emission bands under 350 nm excitation. This mercury-free excitation is useful for solid state lighting and light-emitting diode (LED). Hence it could be useful for solid state lighting and light-emitting diode (LED) application.

Bottom-up electrochemical preparation of solid-state carbon nanodots directly from nitriles/ionic liquids using carbon-free electrodes and the applications in specific ferric ion detection and cell imaging.

Science.gov (United States)

Niu, Fushuang; Xu, Yuanhong; Liu, Mengli; Sun, Jing; Guo, Pengran; Liu, Jingquan

2016-03-14

Carbon nanodots (C-dots), a new type of potential alternative to conventional semiconductor quantum dots, have attracted numerous attentions in various applications including bio-chemical sensing, cell imaging, etc., due to their chemical inertness, low toxicity and flexible functionalization. Various methods including electrochemical (EC) methods have been reported for the synthesis of C-dots. However, complex procedures and/or carbon source-containing electrodes are often required. Herein, solid-state C-dots were simply prepared by bottom-up EC carbonization of nitriles (e.g. acetonitrile) in the presence of an ionic liquid [e.g. 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6)], using carbon-free electrodes. Due to the positive charges of BMIM(+) on the C-dots, the final products presented in a precipitate form on the cathode, and the unreacted nitriles and BMIMPF6 can be easily removed by simple vacuum filtration. The as-prepared solid-state C-dots can be well dispersed in an aqueous medium with excellent photoluminescence properties. The average size of the C-dots was found to be 3.02 ± 0.12 nm as evidenced by transmission electron microscopy. Other techniques such as UV-vis spectroscopy, fluorescence spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy were applied for the characterization of the C-dots and to analyze the possible generation mechanism. These C-dots have been successfully applied in efficient cell imaging and specific ferric ion detection.

Robust Ultraviolet-Visible (UV-Vis) Partial Least-Squares (PLS) Models for Tannin Quantification in Red Wine.

Science.gov (United States)

Aleixandre-Tudo, José Luis; Nieuwoudt, Helené; Aleixandre, José Luis; Du Toit, Wessel J

2015-02-04

The validation of ultraviolet-visible (UV-vis) spectroscopy combined with partial least-squares (PLS) regression to quantify red wine tannins is reported. The methylcellulose precipitable (MCP) tannin assay and the bovine serum albumin (BSA) tannin assay were used as reference methods. To take the high variability of wine tannins into account when the calibration models were built, a diverse data set was collected from samples of South African red wines that consisted of 18 different cultivars, from regions spanning the wine grape-growing areas of South Africa with their various sites, climates, and soils, ranging in vintage from 2000 to 2012. A total of 240 wine samples were analyzed, and these were divided into a calibration set (n = 120) and a validation set (n = 120) to evaluate the predictive ability of the models. To test the robustness of the PLS calibration models, the predictive ability of the classifying variables cultivar, vintage year, and experimental versus commercial wines was also tested. In general, the statistics obtained when BSA was used as a reference method were slightly better than those obtained with MCP. Despite this, the MCP tannin assay should also be considered as a valid reference method for developing PLS calibrations. The best calibration statistics for the prediction of new samples were coefficient of correlation (R 2 val) = 0.89, root mean standard error of prediction (RMSEP) = 0.16, and residual predictive deviation (RPD) = 3.49 for MCP and R 2 val = 0.93, RMSEP = 0.08, and RPD = 4.07 for BSA, when only the UV region (260-310 nm) was selected, which also led to a faster analysis time. In addition, a difference in the results obtained when the predictive ability of the classifying variables vintage, cultivar, or commercial versus experimental wines was studied suggests that tannin composition is highly affected by many factors. This study also discusses the correlations in tannin values between the methylcellulose and protein

Enhancement of UV absorption behavior in Zn O-TiO{sub 2} composites

Energy Technology Data Exchange (ETDEWEB)

Jimenez Reinosa, J.; Leret, P.; Alvarez-Docio, C. M.; Campo, A. del; Fernandez, J. F.

2016-05-01

The ultraviolet -visible, UV-vis, absorption edge behaviour of semiconductor oxides as TiO{sub 2} and ZnO promotes their use as inorganic UV filters for sunscreens. In cosmetics, the use of nanoparticles is favoured because of their higher yield and lower whiteness. However, the particle size effect in the UV absorption is unclear. For this reason, the performances of nano and microsized TiO{sub 2} and ZnO are evaluated in both the UV-vis spectroscopy and the Sun Protection Factor, SPF, value. In order to cover the UV range completely by using inorganic filters a new composite is attempted by dry nano dispersion methodology in which TiO{sub 2} nanoparticles are dispersed onto ZnO microparticles. The new composite shows superior UV absorbing properties and ca. 60% SPF value due to a synergism between components that resulted in extended UV coverage and reduction of the total amount of nanoparticles required in the sunscreens. In addition, nanoparticles are effectively anchored onto microparticles avoiding the presence of free nanoparticles. (Author)

Solid-state devices and applications

CERN Document Server

Lewis, Rhys

1971-01-01

Solid-State Devices and Applications is an introduction to the solid-state theory and its devices and applications. The book also presents a summary of all major solid-state devices available, their theory, manufacture, and main applications. The text is divided into three sections. The first part deals with the semiconductor theory and discusses the fundamentals of semiconductors; the kinds of diodes and techniques in their manufacture; the types and modes of operation of bipolar transistors; and the basic principles of unipolar transistors and their difference with bipolar transistors. The s

Electronic structure and spectroscopic properties of mononuclear manganese(III) Schiff base complexes: a systematic study on [Mn(acen)X] complexes by EPR, UV/vis, and MCD spectroscopy (X = Hal, NCS).

Science.gov (United States)

Westphal, Anne; Klinkebiel, Arne; Berends, Hans-Martin; Broda, Henning; Kurz, Philipp; Tuczek, Felix

2013-03-04

The manganese(III) Schiff base complexes [Mn(acen)X] (H2acen: N,N'-ethylenebis(acetylacetone)imine, X: I(-), Br(-), Cl(-), NCS(-)) are considered as model systems for a combined study of the electronic structure using vibrational, UV/vis absorption, parallel-mode electron paramagnetic resonance (EPR) and low-temperature magnetic circular dichroism (MCD) spectroscopy. By variation of the co-ligand X, the influence of the axial ligand field within a given square-pyramidal coordination geometry on the UV/vis, EPR, and MCD spectra of the title compounds is investigated. Between 25000 and 35000 cm(-1), the low-temperature MCD spectra are dominated by two very intense, oppositely signed pseudo-A terms, referred to as "double pseudo-A terms", which change their signs within the [Mn(acen)X] series dependent on the axial ligand X. Based on molecular orbital (MO) and symmetry considerations, these features are assigned to π(n.b.)(s, a) → yz, z(2) ligand-to-metal charge transfer transitions. The individual MCD signs are directly determined from the calculated MOs of the [Mn(acen)X] complexes. The observed sign change is explained by an inversion of symmetry among the π(n.b.)(s, a) donor orbitals which leads to an interchange of the positive and negative pseudo-A terms constituting the "double pseudo-A term".

Solid-state polymeric dye lasers

CERN Document Server

Singh, S; Sridhar, G; Muthuswamy, V; Raja, K

2003-01-01

This paper presents a review of the organic solid-state polymer materials, which have become established as a new laser media. The photostability of these materials is discussed. Different types of solid-state lasers built around these materials are also reviewed.

Multiple Scattering Principal Component-based Radiative Transfer Model (PCRTM) from Far IR to UV-Vis

Science.gov (United States)

Liu, X.; Wu, W.; Yang, Q.

2017-12-01

Modern satellite hyperspectral satellite remote sensors such as AIRS, CrIS, IASI, CLARREO all require accurate and fast radiative transfer models that can deal with multiple scattering of clouds and aerosols to explore the information contents. However, performing full radiative transfer calculations using multiple stream methods such as discrete ordinate (DISORT), doubling and adding (AD), successive order of scattering order of scattering (SOS) are very time consuming. We have developed a principal component-based radiative transfer model (PCRTM) to reduce the computational burden by orders of magnitudes while maintain high accuracy. By exploring spectral correlations, the PCRTM reduce the number of radiative transfer calculations in frequency domain. It further uses a hybrid stream method to decrease the number of calls to the computational expensive multiple scattering calculations with high stream numbers. Other fast parameterizations have been used in the infrared spectral region reduce the computational time to milliseconds for an AIRS forward simulation (2378 spectral channels). The PCRTM has been development to cover spectral range from far IR to UV-Vis. The PCRTM model have been be used for satellite data inversions, proxy data generation, inter-satellite calibrations, spectral fingerprinting, and climate OSSE. We will show examples of applying the PCRTM to single field of view cloudy retrievals of atmospheric temperature, moisture, traces gases, clouds, and surface parameters. We will also show how the PCRTM are used for the NASA CLARREO project.

Stratospheric OClO and NO2 measured by groundbased UV/Vis-spectroscopy in Greenland in January and February 1990 and 1991

Science.gov (United States)

Roth, A.; Perner, D.

1994-01-01

Groundbased UV/Vis-spectroscopy of zenith scattered sunlight was performed at Sondre Stromfjord (Greenland) during Jan/Feb 1990 and Jan/Feb 1991. Considerable amounts of OClO were observed during both campaigns. Maximum OClO vertical column densities at 92 deg solar zenith angle (SZA) were 7.4 x 10(exp 13) molec/sq cm in 1990 and 5.7 x 10(exp 13) molec/sq cm in 1991 (chemical enhancement is included in the calculation of the air mass factor (AMF)). A threshold seems to exist for OClO detection: OClO was detected on every day when the potential vorticity at the 475 K level of potential temperature was higher than 35 x 10(exp -6)Km(exp 2)kg(exp -1)s(exp -1). NO2 vertical columns lower than 1 x 10(exp 15) molec/sq cm were frequently observed in both winters.

Organic solid-state lasers

CERN Document Server

Forget, Sébastien

2013-01-01

Organic lasers are broadly tunable coherent sources, potentially compact, convenient and manufactured at low-costs. Appeared in the mid 60’s as solid-state alternatives for liquid dye lasers, they recently gained a new dimension after the demonstration of organic semiconductor lasers in the 90's. More recently, new perspectives appeared at the nanoscale, with organic polariton and surface plasmon lasers. After a brief reminder to laser physics, a first chapter exposes what makes organic solid-state organic lasers specific. The laser architectures used in organic lasers are then reviewed, with a state-of-the-art review of the performances of devices with regard to output power, threshold, lifetime, beam quality etc. A survey of the recent trends in the field is given, highlighting the latest developments with a special focus on the challenges remaining for achieving direct electrical pumping of organic semiconductor lasers. A last chapter covers the applications of organic solid-state lasers.

Monitoring Pb in Aqueous Samples by Using Low Density Solvent on Air-Assisted Dispersive Liquid-Liquid Microextraction Coupled with UV-Vis Spectrophotometry.

Science.gov (United States)

Nejad, Mina Ghasemi; Faraji, Hakim; Moghimi, Ali

2017-04-01

In this study, AA-DLLME combined with UV-Vis spectrophotometry was developed for pre-concentration, microextraction and determination of lead in aqueous samples. Optimization of the independent variables was carried out according to chemometric methods in three steps. According to the screening and optimization study, 86 μL of 1-undecanol (extracting solvent), 12 times syringe pumps, pH 2.0, 0.00% of salt and 0.1% DDTP (chelating agent) were chosen as the optimum independent variables for microextraction and determination of lead. Under the optimized conditions, R = 0.9994, and linearity range was 0.01-100 µg mL -1 . LOD and LOQ were 3.4 and 11.6 ng mL -1 , respectively. The method was applied for analysis of real water samples, such as tap, mineral, river and waste water.

Membrane lipid peroxidation by UV-A: Mechanism and implications

International Nuclear Information System (INIS)

Bose, B.; Agarwal, S.; Chatterjee, S.N.

1990-01-01

UV-A produced a dose-dependent linear increase of lipid peroxidation in liposomal membrane, as detected by the assay of (i) conjugated dienes, (ii) lipid hydroperoxides, (iii) malondialdehydes (MDA), and (iv) the fluorescent adducts formed by the reaction of MDA with glycine and also a linear dose-dependent increase of [ 14 C]glucose efflux from the liposomes. UV-A-induced MDA production could not be inhibited by any significant degree by sodium formate, dimethyl sulfoxide, EDTA, or superoxide dismutase but was very significantly inhibited by butylated hydroxytoluene, alpha-tocopherol, sodium azide, L-histidine, dimethylfuran, and beta-carotene. MDA formation increased with an increase in the D 2 O content in water, leading to a maximal amount of nearly 50% enhancement of lipid peroxidation in 100% D 2 O vis-a-vis water used as dispersion medium. The experimental findings indicate the involvement of singlet oxygen as the initiator of the UV-A-induced lipid peroxidation

Structure and spectroscopic study of aqueous Fe(III)-As(V) complexes using UV-Vis, XAS and DFT-TDDFT.

Science.gov (United States)

Chai, Liyuan; Yang, Jinqin; Zhang, Ning; Wu, Pin-Jiun; Li, Qingzhu; Wang, Qingwei; Liu, Hui; Yi, Haibo

2017-09-01

Aqueous complexes between ferric (Fe(III)) and arsenate (As(V)) are indispensable for understanding the mobility of arsenic (As) in Fe(III)-As(V)-rich systems. In this study, aqueous Fe(III)-As(V) complexes, FeH 2 AsO 4 2+ and FeHAsO 4 + , were postulated based on the qualitative analysis of UV-Vis spectra in both Fe(III)-As(V)-HClO 4 and Fe(III)-As(V)-H 2 SO 4 systems. Subsequently, monodentate structures were evidenced by Fe K-edge EXAFS and modeled as [FeH 2 AsO 4 (H 2 O) 5 ] 2+ and [FeHAsO 4 (H 2 O) 5 ] + by DFT. The feature band at ∼280 nm was verified as electron excitation chiefly from Fe-As-bridged O atoms to d-orbital of Fe in [FeH 2 AsO 4 (H 2 O) 5 ] 2+ and [FeHAsO 4 (H 2 O) 5 ] + . The structural and spectral information of Fe(III)-As(V) complexes will enable future speciation analysis in Fe(III)-As(V)-rich system. Copyright © 2017. Published by Elsevier Ltd.

p Ka determinations of xanthene derivates in aqueous solutions by multivariate analysis applied to UV-Vis spectrophotometric data

Science.gov (United States)

Batistela, Vagner Roberto; Pellosi, Diogo Silva; de Souza, Franciane Dutra; da Costa, Willian Ferreira; de Oliveira Santin, Silvana Maria; de Souza, Vagner Roberto; Caetano, Wilker; de Oliveira, Hueder Paulo Moisés; Scarminio, Ieda Spacino; Hioka, Noboru

2011-09-01

Xanthenes form to an important class of dyes which are widely used. Most of them present three acid-base groups: two phenolic sites and one carboxylic site. Therefore, the p Ka determination and the attribution of each group to the corresponding p Ka value is a very important feature. Attempts to obtain reliable p Ka through the potentiometry titration and the electronic absorption spectrophotometry using the first and second orders derivative failed. Due to the close p Ka values allied to strong UV-Vis spectral overlap, multivariate analysis, a powerful chemometric method, is applied in this work. The determination was performed for eosin Y, erythrosin B, and bengal rose B, and also for other synthesized derivatives such as 2-(3,6-dihydroxy-9-acridinyl) benzoic acid, 2,4,5,7-tetranitrofluorescein, eosin methyl ester, and erythrosin methyl ester in water. These last two compounds (esters) permitted to attribute the p Ka of the phenolic group, which is not easily recognizable for some investigated dyes. Besides the p Ka determination, the chemometry allowed for estimating the electronic spectrum of some prevalent protolytic species and the substituents effects evaluation.

Preparation of catalytically active, covalent α-polylysine-enzyme conjugates via UV/vis-quantifiable bis-aryl hydrazone bond formation.

Science.gov (United States)

Grotzky, Andrea; Manaka, Yuichi; Kojima, Taisuke; Walde, Peter

2011-01-10

Covalent UV/vis-quantifiable bis-aryl hydrazone bond formation was investigated for the preparation of conjugates between α-poly-d-lysine (PDL) and either α-chymotrypsin (α-CT) or horseradish peroxidase (HRP). PDL and the enzymes were first modified via free amino groups with the linking reagents succinimidyl 6-hydrazinonicotinate acetone hydrazone (S-HyNic, at pH 7.6) and succinimidyl 4-formylbenzoate (S-4FB, at pH 7.2), respectively. The modified PDL and enzymes were then conjugated at pH 4.7, whereby polymer chains carrying several enzymes were obtained. Kinetics of the bis-aryl hydrazone bond formation was investigated spectrophotometrically at 354 nm. Retention of the enzymatic activity after conjugate formation was confirmed by using the substrates N-succinimidyl-l-Ala-l-Ala-l-Pro-l-Phe-p-nitroanilide (for α-CT) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS, for HRP). Thus, not only a mild and efficient preparation and convenient quantification of a conjugate between the polycationic α-polylysine and enzymes could be shown, but also the complete preservation of the enzymatic activity.

Solid-State NMR Study of New Copolymers as Solid Polymer Electrolytes

Directory of Open Access Journals (Sweden)

Jean-Christophe Daigle

2018-01-01

Full Text Available We report the analysis of comb-like polymers by solid-state NMR. The polymers were previously evaluated as solid-polymer-electrolytes (SPE for lithium-polymer-metal batteries that have suitable ionic conductivity at 60 °C. We propose to develop a correlation between 13C solid-state NMR measurements and phase segregation. 13C solid-state NMR is a perfect tool for differentiating polymer phases with fast or slow motions. 7Li was used to monitor the motion of lithium ions in the polymer, and activation energies were calculated.

Evaluation of the acidity constants of the 4-hidroxy-5-6salicylideneamino9-2-7-naphthalenedisulfonic acid (Azomethine-H) using UV?vis spectrophotometry

Science.gov (United States)

Alarcón-Angeles, G.; Corona-Avendaño, S.; Rojas-Hernández, A.; Romero-Romo, M. A.; Ramírez-Silva, M. T.

2005-01-01

The time stability of the azomethine-H species was determined not to be better than 10 min in the absence of oxygen and light, however under phosphate buffered conditions the azomethine-H species remained stable for longer periods, as indicated by the spectrophotometric behaviour. Nevertheless, the analysis time still exceeded the stability allowance. Therefore, the determination of the acidity constants of the Azomethine-H species was studied by means of UV-vis spectrophotometry in buffered media by means of the point-by-point analysis and data processing with SQUAD to refine the resulting constants, which were: p Ka1=3.39, p Ka2 7.36 and p Ka3 8.73. The latter were associated to the corresponding acid-base equilibria of the amine and hydroxy groups constituting the molecule.

Q-mode curve resolution of UV-vis spectra for structural transformation studies of anthocyanins in acidic solutions

Energy Technology Data Exchange (ETDEWEB)

Marco, Paulo Henrique [Laboratorio de Quimiometria em Ciencias Naturais, Departamento de Quimica, Universidade Estadual de Londrina, Caixa Postal 6001, CEP 86051-970 Londrina, Parana (Brazil); Scarminio, Ieda Spacino [Laboratorio de Quimiometria em Ciencias Naturais, Departamento de Quimica, Universidade Estadual de Londrina, Caixa Postal 6001, CEP 86051-970 Londrina, Parana (Brazil)]. E-mail: ieda@qui.uel.br

2007-01-30

Chemometric analysis of ultraviolet-visible (UV-vis) spectra for pH values 1.0, 3.3, 5.3, and 6.9 was used to investigate the kinetics and the structural transformations of anthocyanins in extracts of calyces of hibiscus flowers of the Hibiscus acetosella Welw. ex Finicius for the first time. Six different species were detected: the quinoidal base (A), the flavylium cation (AH{sup +}), the pseudobase or carbinol pseudobase (B), cis-chalcone (C{sub C}), trans-chalcone (C{sub t}), and ionized cis-chalcone (C{sub C}{sup -}). Four equilibrium constant values were calculated using relative concentrations, hydration, pK{sub h}=2.60+/-0.01, tautomeric, K{sub T}=0.14+/-0.01, acid-base, pK{sub a}=4.24+/-0.04, and ionization of the cis-chalcone, pK{sub C{sub C}}=8.74+/-1.5x10{sup -2}. The calculated protonation rate of the tautomers is K{sub H{sup +}}=0.08+/-7.6x10{sup -3}. These constants are in excellent agreement with those measured previously in salt form. From a kinetic viewpoint, the situation encountered is interesting since the reported investigation is limited to visible light absorption in acid medium. These models have not been reported in the literature.

Solid Lithium Ion Conductors (SLIC) for Lithium Solid State Batteries

Data.gov (United States)

National Aeronautics and Space Administration — To identify the most lithium-ion conducting solid electrolytes for lithium solid state batteries from the emerging types of solid electrolytes, based on a...

Solid state magnetism

CERN Document Server

Crangle, John

1991-01-01

Solid state magnetism is important and attempts to understand magnetic properties have led to an increasingly deep insight into the fundamental make up of solids. Both experimental and theoretical research into magnetism continue to be very active, yet there is still much ground to cover before there can be a full understanding. There is a strong interplay between the developments of materials science and of magnetism. Hundreds of new materials have been dis­ covered, often with previously unobserved and puzzling magnetic prop­ erties. A large and growing technology exists that is based on the magnetic properties of materials. Very many devices used in everyday life involve magnetism and new applications are being invented all the time. Under­ standing the fundamental background to the applications is vital to using and developing them. The aim of this book is to provide a simple, up-to-date introduction to the study of solid state magnetism, both intrinsic and technical. It is designed to meet the needs a...

Synthesis and improved photochromic properties of pyrazolones in the solid state by incorporation of halogen

Science.gov (United States)

Guo, Jixi; Yuan, Hui; Jia, Dianzeng; Guo, Mingxi; Li, Yinhua

2017-01-01

Four novel photochromic pyrazolones have been prepared by introducing halogen atoms as substituents on the benzene ring. All as-synthesized compounds exhibited excellent reversible photochromic performances in the solid state. Upon UV light irradiation, the as-synthesized compounds can change their structures from E-form to K-form with yellow coloration. Further processed by heating, they rapidly reverted to their initial states at 120 °С. Their photo-response and thermal bleaching kinetics were detailed investigated by UV absorption spectra. The results showed that the time constants were higher than that of our previously reported compounds at least one order of magnitude and the rate constants of the as-synthesized compounds were significantly influenced by the size and electronegativity of different halogen atoms. The fluorescence emission were modulated in a high degree via photoisomerization of pyrazolones, which might be due to the efficient energy transfer from E-form to K-form isomers for their partly overlaps between their E-form absorption spectra and K-form fluorescence spectra.

Identification of the silver state in the framework of Ag-containing zeolite by XRD, FTIR, photoluminescence, 109Ag NMR, EPR, DR UV-vis, TEM and XPS investigations.

Science.gov (United States)

Popovych, Nataliia; Kyriienko, Pavlo; Soloviev, Sergiy; Baran, Rafal; Millot, Yannick; Dzwigaj, Stanislaw

2016-10-26

Silver has been identified in the framework of Ag x SiBEA zeolites (where x = 3-6 Ag wt%) by the combined use of XRD, 109 Ag MAS NMR, FTIR, diffuse reflectance UV-visible, EPR and XPS spectroscopy. The incorporation of Ag ions into the framework of SiBEA zeolite has been evidenced by XRD. The consumption of OH groups as a result of their reaction with the silver precursor has been monitored by FTIR and photoluminescence spectroscopy. The changes in the silver state as a function of Ag content and thermal and hydrogen treatment at 573 K have been identified by 109 Ag MAS NMR, EPR, DR UV-visible, TEM and XPS investigations. The acidity of AgSiBEA has been investigated by FTIR spectroscopy of adsorbed CO and pyridine used as probe molecules.

Synthesis of CdSe-TiO_2 Photocatalyst and Their Enhanced Photocatalytic Activities under UV and Visible Light

International Nuclear Information System (INIS)

Lim, Chang Sung; Chen, Ming Liang; Oh, Won Chun

2011-01-01

In this study, CdSe-TiO_2 photocatalyst were synthesized by a facile solvothermal method and characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis and UV-vis diffuse reflectance spectrophotometer. The photocatalytic activity was investigated by degrading methylene blue (MB) in aqueous solution under irradiation of UV light as well as visible light. The absorbance of degraded MB solution was determined by UV-vis spectrophotometer. The results revealed that the CdSe- TiO_2 photocatalyst exhibited much higher photocatalytic activity than TiO_2 both under irradiation of UV light as well as visible light

Enhancement of UV absorption behavior in ZnO–TiO2 composites

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Julián Jiménez Reinosa

2016-03-01

Full Text Available The ultraviolet–visible, UV–vis, absorption edge behaviour of semiconductor oxides as TiO2 and ZnO promotes their use as inorganic UV filters for sunscreens. In cosmetics, the use of nanoparticles is favoured because of their higher yield and lower whiteness. However, the particle size effect in the UV absorption is unclear. For this reason, the performances of nano and microsized TiO2 and ZnO are evaluated in both the UV–vis spectroscopy and the Sun Protection Factor, SPF, value. In order to cover the UV range completely by using inorganic filters a new composite is attempted by dry nanodispersion methodology in which TiO2 nanoparticles are dispersed onto ZnO microparticles. The new composite shows superior UV absorbing properties and ca. 60% SPF value due to a synergism between components that resulted in extended UV coverage and reduction of the total amount of nanoparticles required in the sunscreens. In addition, nanoparticles are effectively anchored onto microparticles avoiding the presence of free nanoparticles.

Characterization and enhanced nonlinear optical limiting response in carbon nanodots dispersed in solid-state hybrid organically modified silica gel glasses

Science.gov (United States)

Huang, Li; Zheng, Chan; Guo, Qiaohang; Huang, Dongdong; Wu, Xiukai; Chen, Ling

2018-02-01

Freely dispersed carbon nanodots (CNDs) were introduced into a 3-glycidoxy-propyltrimethoxysilane modified silicate gel glass (i.e. an organically modified silica or ORMOSIL) by a highly efficient and simple sol-gel process, which could be easily extended to prepare functional molecules/nanoparticles solid state optoelectronic devices. Scanning electron microscope imaging, Fourier transform infrared spectroscopy, pore structure measurements, ultraviolet-visible spectroscopy, and fluorescence spectroscopy were used to investigate the surface characteristics, structure, texture, and linear optical properties of the CND/SiO2 ORMOSIL gel glasses. Images and UV/Vis spectra confirmed the successful dispersion of CNDs in the ORMOSIL gel glass. The surface characteristics and pore structure of the host SiO2 matrix were markedly changed through the introduction of the CNDs. The linear optical properties of the guest CNDs were also affected by the sol-gel procedure. The nonlinear optical (NLO) properties of the CNDs were investigated by a nanosecond open-aperture Z-scan technique at 532 nm both in liquid and solid matrices. We found that the NLO response of the CNDs was considerably improved after their incorporation into the ORMOSIL gel glasses. Possible enhancement mechanisms were also explored. The nonlinear extinction coefficient gradually increased while the optical limiting (OL) threshold decreased as the CND doping level was increased. This result suggests that the NLO and OL properties of the composite gel glasses can be optimized by tuning the concentration of CNDs in the gel glass matrix. Our findings show that CND/SiO2 ORMOSIL gel glasses are promising candidates for optical limiters to protect sensitive instruments and human eyes from damage caused by high power lasers.

Determinação do teor de sílica em madeira por espectroscopia de absorção atômica de chama versus espectroscopia no ultravioleta-visível.

Directory of Open Access Journals (Sweden)

Laécio Carneiro Rodrigues

2009-10-01

Full Text Available Normal 0 21 MicrosoftInternetExplorer4 O presente trabalho teve como objetivo comparar o desempenho de duas técnicas analíticas, espectroscopia de absorção atômica de chama (FAAS e espectroscopia no ultravioleta-visível (UV-VIS, na determinação do teor de sílica em materiais lignocelulósicos. Os métodos foram testados em amostras de madeira de três árvores de Apuleia leiocarpa (Vog. Macbride. Os resultados mostraram que ambas as técnicas apresentam bons resultados, no entanto, a FAAS apresenta melhor precisão, rapidez e simplicidade operacional. Entretanto, a aplicação da espectroscopia UV-VIS é justificada pelo fato de os custos de aquisição e manutenção de um espectrofotômetro UV-VIS serem muito inferiores àqueles de um espectrômetro de absorção atômica. O uso da técnica FAAS deve ser preferido apenas quando os teores de sílica a serem determinados forem muito baixos, tendo em vista que a espectroscopia UV-VIS, nesses casos, não apresenta boa precisão.

High-powered, solid-state rf systems

International Nuclear Information System (INIS)

Reid, D.W.

1987-01-01

Over the past two years, the requirement to supply megawatts of rf power for space-based applications at uhf and L-band frequencies has caused dramatic increases in silicon solid-state power capabilities in the frequency range from 10 to 3000 MHz. Radar and communications requirements have caused similar increases in gallium arsenide solid-state power capabilities in the frequency ranges from 3000 to 10,000 MHz. This paper reviews the present state of the art for solid-state rf amplifiers for frequencies from 10 to 10,000 MHz. Information regarding power levels, size, weight, and cost will be given. Technical specifications regarding phase and amplitude stability, efficiency, and system architecture will be discussed. Solid-stage rf amplifier susceptibility to radiation damage will also be examined

Ultraviolet/visible and Fourier transform infrared spectroscopic investigations of organic–inorganic hybrid layers for UV protection

Energy Technology Data Exchange (ETDEWEB)

Präfke, Christiane, E-mail: christiane.praefke@iof.fraunhofer.de [Fraunhofer Institute of Applied Optics and Precision Engineering, Optical Coatings Department, Albert-Einstein-Straße 7, 07745 Jena (Germany); Institute of Applied Physics, Abbe Center of Photonics, Friedrich-Schiller-Universität Jena (Germany); Schulz, Ulrike, E-mail: ulrike.schulz@iof.fraunhofer.de [Fraunhofer Institute of Applied Optics and Precision Engineering, Optical Coatings Department, Albert-Einstein-Straße 7, 07745 Jena (Germany); Kaiser, Norbert, E-mail: norbert.kaiser@iof.fraunhofer.de [Fraunhofer Institute of Applied Optics and Precision Engineering, Optical Coatings Department, Albert-Einstein-Straße 7, 07745 Jena (Germany); Tünnermann, Andreas, E-mail: andreas.tuennermann@iof.fraunhofer.de [Fraunhofer Institute of Applied Optics and Precision Engineering, Optical Coatings Department, Albert-Einstein-Straße 7, 07745 Jena (Germany); Institute of Applied Physics, Abbe Center of Photonics, Friedrich-Schiller-Universität Jena (Germany)

2013-04-01

A study of vacuum-deposited organic–inorganic hybrid coatings for ultraviolet (UV) protection of polycarbonate is presented. For this purpose, UV-absorbing organic molecules were embedded in a silica matrix by thermal co-evaporation. Typical UV absorbers, namely a benzotriazole, a hydroxyphenyltriazine, and a cyanoacrylate, were used as organic materials. The hybrid layers were investigated by means of ultraviolet/visible (UV/VIS) and Fourier transform infrared spectroscopy (FTIR) concerning their UV/VIS absorption properties and the influence of the silica network on the organic molecules. The porosity and silica–organic interactions are discussed with reference to the infrared spectra. UV irradiation experiments were carried out to demonstrate the UV protection ability of the hybrid layers. Hybrid layers containing the hydroxyphenyltriazine compound showed the best results. - Highlights: ► Vacuum deposited organic–inorganic UV protective coatings for polycarbonate ► Thermal co-evaporation of organic UV absorbing compounds with silica ► Matrix materials and the absorber concentration influence the absorption behavior. ► The coatings on PC show improved UV stability under artificial irradiation. ► The hydroxyphenyltriazine–silica layer shows best UV protection results.

Solid-state lithium battery

Science.gov (United States)

Ihlefeld, Jon; Clem, Paul G; Edney, Cynthia; Ingersoll, David; Nagasubramanian, Ganesan; Fenton, Kyle Ross

2014-11-04

The present invention is directed to a higher power, thin film lithium-ion electrolyte on a metallic substrate, enabling mass-produced solid-state lithium batteries. High-temperature thermodynamic equilibrium processing enables co-firing of oxides and base metals, providing a means to integrate the crystalline, lithium-stable, fast lithium-ion conductor lanthanum lithium tantalate (La.sub.1/3-xLi.sub.3xTaO.sub.3) directly with a thin metal foil current collector appropriate for a lithium-free solid-state battery.

Estratégias para aumento de sensibilidade em espectrofotometria UV-VIS Strategies to increase sensitivity in UV-VIS spectrophotometry

Directory of Open Access Journals (Sweden)

Fábio R. P. Rocha

2004-10-01

Full Text Available Spectrophotometry is one of the most widespread analytical techniques due to its simplicity, reliability, and low-cost instrumentation for both direct measurements and coupled to other techniques or processes such as chromatography, electrophoresis and flow analysis. However, the application is often limited by sensitivity. This article describes some advances that greatly improve the performance of spectrophotometric measurements, especially in order to increase sensitivity, including the employment of liquid-core waveguides and solid-phase spectrophotometry.

Experimental conditions affecting the kinetics of aqueous HCN polymerization as revealed by UV-vis spectroscopy.

Science.gov (United States)

Marín-Yaseli, Margarita R; Moreno, Miguel; de la Fuente, José L; Briones, Carlos; Ruiz-Bermejo, Marta

2018-02-15

HCN polymerization is one of the most important and fascinating reactions in prebiotic chemistry, and interest in HCN polymers in the field of materials science is growing. However, little is known about the kinetics of the HCN polymerization process. In the present study, a first approach to the kinetics of two sets of aqueous HCN polymerizations, from NH 4 CN and NaCN, at middle temperatures between 4 and 38°C, has been carried out. For each series, the presence of air and salts in the reaction medium has been systematically explored. A previous kinetic analysis was conducted during the conversion of the insoluble black HCN polymers obtained as gel fractions in these precipitation polymerizations for a reaction of one month, where a limit conversion was achieved at the highest polymerization temperature. The kinetic description of the gravimetric data for this complex system shows a clear change in the linear dependence with the polymerization temperature for the reaction from NH 4 CN, besides a relevant catalytic effect of ammonium, in comparison with those data obtained from the NaCN series. These results also demonstrated the notable influence of air, oxygen, and the saline medium in HCN polymer formation. Similar conclusions were reached when the sol fractions were monitored by UV-vis spectroscopy, and a Hill type correlation was used to describe the polymerization profiles obtained. This technique was chosen because it provides an easy, prompt and fast method to follow the evolution of the liquid or continuous phase of the process under study. Copyright © 2017 Elsevier B.V. All rights reserved.

UV-visible-DAD and 1H-NMR spectroscopy data fusion for studying the photodegradation process of azo-dyes using MCR-ALS.

Science.gov (United States)

Fernández, Cristina; Pilar Callao, M; Larrechi, M Soledad

2013-12-15

The photodegradation process of three azo-dyes - Acid Orange 61, Acid Red 97 and Acid Brown 425 - was monitored simultaneously by ultraviolet-visible spectroscopy with diode array detector (UV-vis-DAD) and (1)H-nuclear magnetic resonance ((1)H-NMR). Multivariate curve resolution-alternating least squares (MCR-ALS) was applied to obtain the concentration and spectral profile of the chemical compounds involved in the process. The analysis of the H-NMR data suggests there are more intermediate compounds than those obtained with the UV-vis-DAD data. The fusion of UV-vis-DAD and the (1)H-NMR signal before the multivariate analysis provides better results than when only one of the two detector signals was used. It was concluded that three degradation products were present in the medium when the three azo-dyes had practically degraded. This study is the first application of UV-vis-DAD and (1)H-NMR spectroscopy data fusion in this field and illustrates its potential as a quick method for evaluating the evolution of the azo-dye photodegradation process. © 2013 Elsevier B.V. All rights reserved.

Retrieving simulated volcanic, desert dust and sea-salt particle properties from two/three-component particle mixtures using UV-VIS polarization lidar and T matrix

Directory of Open Access Journals (Sweden)

G. David

2013-07-01

Full Text Available During transport by advection, atmospheric nonspherical particles, such as volcanic ash, desert dust or sea-salt particles experience several chemical and physical processes, leading to a complex vertical atmospheric layering at remote sites where intrusion episodes occur. In this paper, a new methodology is proposed to analyse this complex vertical layering in the case of a two/three-component particle external mixtures. This methodology relies on an analysis of the spectral and polarization properties of the light backscattered by atmospheric particles. It is based on combining a sensitive and accurate UV-VIS polarization lidar experiment with T-matrix numerical simulations and air mass back trajectories. The Lyon UV-VIS polarization lidar is used to efficiently partition the particle mixture into its nonspherical components, while the T-matrix method is used for simulating the backscattering and depolarization properties of nonspherical volcanic ash, desert dust and sea-salt particles. It is shown that the particle mixtures' depolarization ratio δ p differs from the nonspherical particles' depolarization ratio δns due to the presence of spherical particles in the mixture. Hence, after identifying a tracer for nonspherical particles, particle backscattering coefficients specific to each nonspherical component can be retrieved in a two-component external mixture. For three-component mixtures, the spectral properties of light must in addition be exploited by using a dual-wavelength polarization lidar. Hence, for the first time, in a three-component external mixture, the nonsphericity of each particle is taken into account in a so-called 2β + 2δ formalism. Applications of this new methodology are then demonstrated in two case studies carried out in Lyon, France, related to the mixing of Eyjafjallajökull volcanic ash with sulfate particles (case of a two-component mixture and to the mixing of dust with sea-salt and water-soluble particles

Fluidized Bed Reactor as Solid State Fermenter

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Krishnaiah, K.

2005-01-01

Full Text Available Various reactors such as tray, packed bed, rotating drum can be used for solid-state fermentation. In this paper the possibility of fluidized bed reactor as solid-state fermenter is considered. The design parameters, which affect the performances are identified and discussed. This information, in general can be used in the design and the development of an efficient fluidized bed solid-state fermenter. However, the objective here is to develop fluidized bed solid-state fermenter for palm kernel cake conversion into enriched animal and poultry feed.

Solid state physics for metallurgists

CERN Document Server

Weiss, Richard J

2013-01-01

Metal Physics and Physical Metallurgy, Volume 6: Solid State Physics for Metallurgists provides an introduction to the basic understanding of the properties that make materials useful to mankind. This book discusses the electronic structure of matter, which is the domain of solid state physics.Organized into 12 chapters, this volume begins with an overview of the electronic structure of free atoms and the electronic structure of solids. This text then examines the basis of the Bloch theorem, which is the exact periodicity of the potential. Other chapters consider the fundamental assumption in

Solid-State Powered X-band Accelerator

Energy Technology Data Exchange (ETDEWEB)

Othman, Mohamed A.K. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Nann, Emilio A. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Dolgashev, Valery A. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Tantawi, Sami [SLAC National Accelerator Lab., Menlo Park, CA (United States); Neilson, Jeff [SLAC National Accelerator Lab., Menlo Park, CA (United States)

2017-03-06

In this report we disseminate the hot test results of an X-band 100-W solid state amplifier chain for linear accelerator (linac) applications. Solid state power amplifiers have become increasingly attractive solutions for achieving high power in radar and maritime applications. Here the performance of solid state amplifiers when driving an RF cavity is investigated. Commercially available, matched and fully-packaged GaN on SiC HEMTs are utilized, comprising a wideband driver stage and two power stages. The amplifier chain has a high poweradded- efficiency and is able to supply up to ~1.2 MV/m field gradient at 9.2 GHz in a simple test cavity, with a peak power exceeding 100 W. These findings set forth the enabling technology for solid-state powered linacs.

A new method for the quantification of monosaccharides, uronic acids and oligosaccharides in partially hydrolyzed xylans by HPAEC-UV/VIS.

Science.gov (United States)

Lorenz, Dominic; Erasmy, Nicole; Akil, Youssef; Saake, Bodo

2016-04-20

A new method for the chemical characterization of xylans is presented, to overcome the difficulties in quantification of 4-O-methyl-α-D-glucuronic acid (meGlcA). In this regard, the hydrolysis behavior of xylans from beech and birch wood was investigated to obtain the optimum conditions for hydrolysis, using sulfuric acid. Due to varying linkage strengths and degradation, no general method for complete hydrolysis can be designed. Therefore, partial hydrolysis was applied, yielding monosaccharides and small meGlcA containing oligosaccharides. For a new method by HPAEC-UV/VIS, these samples were reductively aminated by 2-aminobenzoic acid. By quantification of monosaccharides and oligosaccharides, as well as comparison with borate-HPAEC and (13)C NMR-spectroscopy, we revealed that the concentrations meGlcA are significantly underestimated compared to conventional methods. The detected concentrations are 85.4% (beech) and 76.3% (birch) higher with the new procedure. Furthermore, the quantified concentrations of xylose were 9.3% (beech) and 6.5% (birch) higher by considering the unhydrolyzed oligosaccharides as well. Copyright © 2015 Elsevier Ltd. All rights reserved.

APPLICATION OF QuEChERS METHOD FOR THE DETERMINATION OF PHENYLUREA HERBICIDES IN BEETROOT BY HPLC WITH UV-VIS DETECTION

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Magdalena Surma

2015-02-01

Full Text Available Phenylurea herbicides are an important group of herbicides utilized in weed control. They have been on sale since the 1950s and are still in common use throughout the world from pre- and post-emergence control of many annual and perennial broad-leaved weeds. The aim of this work was to evaluate the utility of the QuEChERS method for the determination of phenylurea pesticides (chlortoluron, isoproturon, linuron, metobromuron, metoxuron, monolinuron in beetroot by HPLC with UV/Vis detection. Different types of sorbents (PSA, C18, SAX and NH2 and solvents (hexane, ethyl acetate were applied. The obtained results showed that the best recovery ratios were received for the method with PSA and GCB sorbents and using acetonitrile as an extraction solvent with RSD lower than 15% for most compounds. The linearity of calibration curves was higher than 0.98 for all target analytes. The results show that the QuEChERS method can be successfully applied for the determination of phenylurea herbicides in beetroot.

UV-vis light transmittance through tinted contact lenses and the effect of color on values.

Science.gov (United States)

Osuagwu, Uchechukwu L; Ogbuehi, Kelechi C

2014-06-01

To assess the transmittance, in the 200-700nm electromagnetic radiation spectrum, by popularly used tinted soft contact lenses (CLs). The spectra transmittances of ultraviolet (UV)-blocking (I Day Acuvue Define, Freshlook ONE DAY) and non-UV-blocking (Durasoft 3, Tutti, and NeoCosmo) tinted soft CLs were tested. The transmittance of each lens, including nine different colors of Freshlook CL was recorded on spectrophotometer, and the data used to also calculate a UV protection factor (PF) for each lens brand tested, with a higher value indicating a higher level of protection. The UV-blocking CLs significantly reduced UVC, UVB & UVA transmission and thereby meet the American National Standards Institution standard for class 2 UV blockers: a maximum of 30% transmittance of UVA and 5% transmittance of UVB wavelengths. In contrast, the Durasoft 3, Tutti, and NeoCosmo CLs demonstrated negligible UV-blockage. The Acuvue Define CL offered the greatest protection from UVC (PF=69) and UVB (PF=55), but with only 35% luminous transmittance, while the Freshlook CL (especially gemstone green) offered the best protection from UVA (PF=24) and showed about 55% translucency. Overall, the UV-blocking CLs performed equally well across the UV spectrum. Different colors of Freshlook CL transmitted statistically and clinically significantly different amounts of visible light but similar amounts of UVR. Freshlook and Acuvue Define CLs which are designated as UV-blockers significantly reduced UVR transmission to safe levels whereas Tutti, NeoCosmo and Durasoft 3 did not. Transmission within the Freshlook CL family was more dependent on color in the visible light spectrum, but not in the UV-spectrum, where the gemstone green performing best among the tested colors. Copyright © 2013 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

The electrochemical oxidation of sulfite on gold: UV-Vis reflectance spectroscopy at a rotating disk electrode

International Nuclear Information System (INIS)

Tolmachev, Yuriy V.; Scherson, Daniel A.

2004-01-01

Certain aspects of the electrochemical oxidation of sulfite in buffered, mildly acidic aqueous solutions (pH 5.23) have been examined using in situ near normal incidence UV-Vis reflectance spectroscopy (NNI-UVRS) at a Au rotating disk electrode (RDE). The dependence of the limiting current, i lim , on the rotation rate of the RDE was found to display classical Levich behavior up to potentials well within the range in which Au forms a surface oxide in the neat (sulfite-free) supporting electrolyte. However, simultaneous in situ NNI-UVRS measurements performed at λ=500 nm during sulfite oxidation failed to show any evidence for the presence of oxide on the Au surface within that entire potential range. Polarization of the Au RDE at more positive potentials led to a sudden drop in i lim , ca. an order of magnitude, which correlated with an abrupt decrease in the intensity of the reflected light, consistent with formation of (one or more forms of) Au oxide on the surface. On the basis of these and other observations a model has been proposed in which sulfite reacts chemically with adsorbed oxygen on the surface (oxygen atom transfer) in the region that precedes partial inhibition. As the potential is increased, adsorbed oxygen undergoes Au-O place exchange forming two-dimensional nuclei on the surface, which undergo rapid (autocatalytic) growth, covering an area large enough to block significantly sulfite oxidation

Simple and Selective HPLC-UV/Vis Bioanalytical Method to Determine Aluminum Phthalocyanine Chloride in Skin Permeation Studies

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Thaiene Avila Reis

2018-01-01

Full Text Available Considering the feasibility of the aluminum phthalocyanine chloride (AlPcCl application in the topical photodynamic therapy of cutaneous tumors and the lack of HPLC methods capable of supporting skin permeation experiments using this compound, the aim of this study was to obtain a simple and selective chromatographic method for AlPcCl determination in skin matrices. A HPLC-UV/Vis method was developed using a normal-phase column operating at 30°C, an isocratic mobile phase of methanol : phosphoric acid (0.01 M at 1.5 mL/min, and detection at 670 nm. The method exhibited (i selectivity against various contaminants found in the different skin layers, (ii high drug extraction capacity from the hair follicle (>70% and remaining skin (>80%, and (iii low limits of detection and of quantification (0.03 and 0.09 μg/mL, resp.. The method was also linear in the range from 0.1 to 5.0 µg/mL (r = 0.9994 and demonstrated robustness with regard to experimental chromatographic parameters according to a factorial design. Lastly, the developed method was successfully tested in in vitro skin permeation studies of AlPcCl, proving its effectiveness in the development of pharmaceutical delivery systems containing this drug for topical photodynamic therapy of skin cancers.

/UV Synergistic Aging of Polyester Polyurethane Film Modified by Composite UV Absorber

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Yanzhi Wang

2013-01-01

Full Text Available The pure polyester polyurethane (TPU film and the modified TPU (M-TPU film containing 2.0 wt.% inorganic UV absorbers mixture (nano-ZnO/CeO2 with weight ratio of 3 : 2 and 0.5 wt.% organic UV absorbers mixture (UV-531/UV-327 with weight ratio of 1 : 1 were prepared by spin-coating technique. The accelerated aging tests of the films exposed to constant UV radiation of 400 ± 20 µW/cm2 (313 nm with an ozone atmosphere of 100 ± 2 ppm were carried out by using a self-designed aging equipment at ambient temperature and relative humidity of 20%. The aging resistance properties of the films were evaluated by UV-Vis spectra, Fourier transform infrared spectra (FT-IR, photooxidation index, and carbonyl index analysis. The results show that the composite UV absorber has better protection for TPU system, which reduces distinctly the degradation of TPU film. O3/UV aging of the films increases with incremental exposure time. PI and CI of TPU and M-TPU films increase with increasing exposure time, respectively. PI and CI of M-TPU films are much lower than that of TPU film after the same time of exposure, respectively. Distinct synergistic aging effect exists between ozone aging and UV aging when PI and CI are used as evaluation index, respectively. Of course, the formula of these additives needs further improvement for industrial application.

Transmission of UV-irradiance into nectarine fruit

International Nuclear Information System (INIS)

Blanke, M.M.

1996-01-01

With the global depletion of the ozone layer, leaves and fruits are increasingly exposed to UV-irradiance on the tree. Some fruits are additionally exposed postharvest to artificial germicidal W-irradiance, leading to a cumulative effect. This paper examines the transmission of UV-light (200-400 nm) by the peel of ripe nectarine fruit using UV/VIS spectrophotometry to aid understanding of UV-effects and assess the sensitivity of the peel to UV wavelengths. Yellow peel of nectarine fruit transmitted less than 0.1 % in the UV-C range of 220 to 280 nm. With longer wavelenghts, UV-light transmission increased slowly from 0.4 % at 284 nm to 1.6 % at 320 nm and, in the UV-A region, progressively from 1.9 % at 330 nm to a maximum of 13 % of incident irradiance at 400 nm. Red peel of nectarine fruit transmitted less than 0.1 % of UV-C and UV-B light, but up to 0.9 % of incident UV-A light at 400 nm. Conversely, UV-absorption of nectarine peel decreased with longer wavelengths. Hence, fruit parenchyma is more affected by UV-irradiance at wavelengths above ca. 280 nm and underneath yellow than underneath red peel

Detection and characterization of silver nanoparticles and dissolved species of silver in culture medium and cells by AsFlFFF-UV-Vis-ICPMS: application to nanotoxicity tests.

Science.gov (United States)

Bolea, E; Jiménez-Lamana, J; Laborda, F; Abad-Álvaro, I; Bladé, C; Arola, L; Castillo, J R

2014-03-07

A methodology based on Asymmetric Flow Field-Flow Fractionation (AsFlFFF) coupled with UV-Vis absorption spectrometry and ICP mass spectrometry (ICPMS) has been developed and applied to the study of silver nanoparticles (AgNPs) and dissolved species of silver in culture media and cells used in cytotoxicity tests. The effect of a nano-silver based product (protein stabilized silver nanoparticles ca. 15 nm average diameter) on human hepatoma (HepG2) cell viability has been studied. UV-Vis absorption spectrometry provided information about the nature (organic vs. nanoparticle) of the eluted species, whereas the silver was monitored by ICPMS. A shift towards larger hydrodynamic diameters was observed in the AgNPs after a 24 hour incubation period in the culture medium, which suggests a "protein corona" effect. Silver(I) associated with proteins present in the culture medium has also been detected, as a consequence of the oxidation process experimented by the AgNPs. However, the Ag(I) released into the culture medium did not justify the toxicity levels observed. AgNPs associated with the cultured HepG2 cells were also identified by AsFlFFF, after applying a solubilisation process based on the use of tetramethylammonium hydroxide (TMAH) and Triton X-100. These results have been confirmed by transmission electronic microscopy (TEM) analysis of the fractions collected from the AsFlFFF. The effect of AgNPs on HepG2 cells has been compared to that caused by silver(I) as AgNO3 under the same conditions. The determination of the total content of silver in the cells confirms that a much larger mass of silver as AgNPs with respect to AgNO3 (16 to 1) is needed to observe a similar toxicity.

Solid-state lighting-a benevolent technology

International Nuclear Information System (INIS)

Schubert, E Fred; Kim, Jong Kyu; Luo Hong; Xi, J-Q

2006-01-01

Solid-state light sources are in the process of profoundly changing the way humans generate light for general lighting applications. Solid-state light sources possess two highly desirable features, which set them apart from most other light sources: (i) they have the potential to create light with essentially unit power efficiency and (ii) the properties of light, such as spectral composition and temporal modulation, can be controlled to a degree that is not possible with conventional light sources such as incandescent and fluorescent lamps. The implications are enormous and, as a consequence, many positive developments are to be expected including a reduction in global energy consumption, reduction of global-warming-gas and pollutant emissions and a multitude of new functionalities benefiting numerous applications. This review will assess the impact of solid-state lighting technology on energy consumption, the environment and on emerging application fields that make use of the controllability afforded by solid-state sources. The review will also discuss technical areas that fuel continued progress in solid-state lighting. Specifically, we will review the use of novel phosphor distributions in white light-emitting diodes (LEDs) and show the strong influence of phosphor distribution on efficiency. We will also review the use of reflectors in LEDs with emphasis on 'perfect' reflectors, i.e. reflectors with highly reflective omni-directional characteristics. Finally, we will discuss a new class of thin-film materials with an unprecedented low refractive index. Such low-n materials may strongly contribute to the continuous progress in solid-state lighting

Solid state opto-impedance of LiNiVO{sub 4} and LiMn{sub 2}O{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Kalyani, P; Sivasubramanian, S; Prabhu, S Naveen; Ragavendran, K; Kalaiselvi, N; Ranganathan, N G; Madhu, S; SundaraRaj, A; Manoharan, S P; Jagannathan, R [Central Electrochemical Research Institute, Karaikudi-630006, Tamil Nadu (India)

2005-04-07

Spinel type LiMn{sub 2}O{sub 4} and inverse spinel LiNiVO{sub 4} systems serve as standard cathode materials or potential cathode systems for application in high energy density lithium-ion batteries. Upon photo-excitation using UV radiation of energy {approx}5 eV, the LiNiVO{sub 4} system shows significant modification in the solid state impedance pattern while the LiMn{sub 2}O{sub 4} system does not. This study has revealed a significant difference in the opto-impedance pattern for LiNiVO{sub 4} with respect to LiMn{sub 2}O{sub 4}, which may be due to the different electronic processes involved. An attempt has been made to study this behaviour from the solid-state viewpoint.

Depth probing of the hydride formation process in thin Pd films by combined electrochemistry and fiber optics-based in situ UV/vis spectroscopy.

Science.gov (United States)

Wickman, Björn; Fredriksson, Mattias; Feng, Ligang; Lindahl, Niklas; Hagberg, Johan; Langhammer, Christoph

2015-07-15

We demonstrate a flexible combined electrochemistry and fiber optics-based in situ UV/vis spectroscopy setup to gain insight into the depth evolution of electrochemical hydride and oxide formation in Pd films with thicknesses of 20 and 100 nm. The thicknesses of our model systems are chosen such that the films are thinner or significantly thicker than the optical skin depth of Pd to create two distinctly different situations. Low power white light is irradiated on the sample and analyzed in three different configurations; transmittance through, and, reflectance from the front and the back side of the film. The obtained optical sensitivities correspond to fractions of a monolayer of adsorbed or absorbed hydrogen (H) and oxygen (O) on Pd. Moreover, a combined simultaneous readout obtained from the different optical measurement configurations provides mechanistic insights into the depth-evolution of the studied hydrogenation and oxidation processes.

Two dimensional solid state NMR

International Nuclear Information System (INIS)

Kentgens, A.P.M.

1987-01-01

This thesis illustrates, by discussing some existing and newly developed 2D solid state experiments, that two-dimensional NMR of solids is a useful and important extension of NMR techniques. Chapter 1 gives an overview of spin interactions and averaging techniques important in solid state NMR. As 2D NMR is already an established technique in solutions, only the basics of two dimensional NMR are presented in chapter 2, with an emphasis on the aspects important for solid spectra. The following chapters discuss the theoretical background and applications of specific 2D solid state experiments. An application of 2D-J resolved NMR, analogous to J-resolved spectroscopy in solutions, to natural rubber is given in chapter 3. In chapter 4 the anisotropic chemical shift is mapped out against the heteronuclear dipolar interaction to obtain information about the orientation of the shielding tensor in poly-(oxymethylene). Chapter 5 concentrates on the study of super-slow molecular motions in polymers using a variant of the 2D exchange experiment developed by us. Finally chapter 6 discusses a new experiment, 2D nutation NMR, which makes it possible to study the quadrupole interaction of half-integer spins. 230 refs.; 48 figs.; 8 tabs

Formation of nanoparticles and nanorods via UV irradiation of AgNO3 solutions

International Nuclear Information System (INIS)

Szymanska-Chargot, M.; Gruszecka, A.; Smolira, A.; Bederski, K.; Gluch, K.; Cytawa, J.; Michalak, L.

2009-01-01

The synthesis of silver nanoparticles via UV irradiation of AgNO 3 solutions was controlled by using UV-vis absorption spectra and TEM (transmission electron microscope) images. The UV-vis absorption method is good enough for the general control of synthesis process, and TEM images give us information about size of formed species. For investigated solutions of silver nitrate in ethanol and water, we observed formation of large nanoparticles (size about 100 nm) and nanorods (100 nm in length). Moreover, there was effort to confirm evidence of formation of these particles by using TOF mass spectrometer. Due to laser desorption/ionization process there is only evidence of small silver nanoparticles Ag x , x ≤ 4 (clusters), and variety of silver compounds Ag x N y O z (x ≤ 5, y ≤ 2, z ≤ 3).

UV, visible and IR laser interaction with gelatine

International Nuclear Information System (INIS)

Oujja, M; Rebollar, E; Abrusci, C; Amo, A Del; Catalina, F; Castillejo, M

2007-01-01

In this work we investigate the effects on gelatine films of nanosecond pulsed laser irradiation at different laser wavelengths from the UV to the IR at 248, 266, 355, 532 and 1064 nm. We compared gelatines differing in gel strength values (Bloom 75 and 225) and in crosslinking degree. Formation of bubbles at the wavelengths in the UV (248 and 266 nm), melting and resolidification at 355 nm, and formation of craters by ablation in the VIS and IR (532 and 1064 nm) are the observed morphological changes. On the other hand, changes of the fluorescence behaviour of the films upon UV irradiation reveal chemical modifications of photolabile chromophores

Macroscopic modelling of solid-state fermentation

NARCIS (Netherlands)

Hoogschagen, M.J.

2007-01-01

Solid-state fermentation is different from the more well known process of liquid fermentation because no free flowing water is present. The technique is primarily used in Asia. Well-known products are the foods tempe, soy sauce and saké. In industrial solid-state fermentation, the substrate usually

DETERMINAÇÃO DE ENXOFRE EM SHAMPOO POR ESPECTROFOTOMETRIA UV-VIS: AVALIAÇÃO DE MÉTODOS DE PREPARO DE AMOSTRAS

Directory of Open Access Journals (Sweden)

Natalia J. Bielemann

Full Text Available Dry ashing, dissolution in aqueous medium or wet digestion methods were evaluated for sample preparation of shampoo for the subsequent indirect determination of sulfur by UV-Vis spectrophotometry. Among the sample preparation methods evaluated, microwave-assisted wet digestion using 7 mol L-1 HNO3 was the most suitable method for this purpose. Accuracy of the proposed method was evaluated by recovery test using standard solution, and the recovery was about 96%. Moreover, for comparison of results, S (as SO42- was also determined by ion chromatography, after microwave-assisted wet digestion using concentrated HNO3, and no significant difference was observed between the obtained results (according to the t-test for a 95% confidence level, p = 0.288. Relative standard deviations were always lower than 10% and the limit of detection was 0.007% w/v. Finally, the proposed method was applied for analysis of sixteen shampoos used to many types of hair, from different brands produced in Brazil, and the concentration of S ranged from 0.78 to 2.82% w/v.

Online Monitoring of Water-Quality Anomaly in Water Distribution Systems Based on Probabilistic Principal Component Analysis by UV-Vis Absorption Spectroscopy

Directory of Open Access Journals (Sweden)

Dibo Hou

2014-01-01

Full Text Available This study proposes a probabilistic principal component analysis- (PPCA- based method for online monitoring of water-quality contaminant events by UV-Vis (ultraviolet-visible spectroscopy. The purpose of this method is to achieve fast and sound protection against accidental and intentional contaminate injection into the water distribution system. The method is achieved first by properly imposing a sliding window onto simultaneously updated online monitoring data collected by the automated spectrometer. The PPCA algorithm is then executed to simplify the large amount of spectrum data while maintaining the necessary spectral information to the largest extent. Finally, a monitoring chart extensively employed in fault diagnosis field methods is used here to search for potential anomaly events and to determine whether the current water-quality is normal or abnormal. A small-scale water-pipe distribution network is tested to detect water contamination events. The tests demonstrate that the PPCA-based online monitoring model can achieve satisfactory results under the ROC curve, which denotes a low false alarm rate and high probability of detecting water contamination events.

UV-LED Curing Efficiency of Wood Coatings

Directory of Open Access Journals (Sweden)

Véronic Landry

2015-12-01

Full Text Available Ultraviolet light emitting diodes (UV-LEDs have attracted great interest in recent years. They can be used to polymerize coatings, such as those used for prefinished wood flooring. In this project, two lamps were compared for their suitability to be used on a wood flooring finishing line: a UV-microwave and a UV-LED lamp. Low heat emission was found for the UV-LED lamp compared to the UV-microwave one. This study also reveals that the 4 W/cm2 UV-LED lamp used is not powerful enough to cure UV high solids acrylate coatings while satisfactory results can be obtained for UV water-based formulations. In fact, conversion percentages were found to be low for the high solids coatings, leaving the coatings tacky. Higher conversion percentages were obtained for the UV water-based formulations. As a result, mass loss, hardness, and scratch resistance found for the samples cured by UV-LED were closed to the ones found for the samples cured using the UV microwave lamp.

Synthesis, spectroscopic, and molecular structure characterizations of some azo derivatives of 2-hydroxyacetophenone

Science.gov (United States)

Albayrak, Çiğdem; Gümrükçüoğlu, İsmail E.; Odabaşoğlu, Mustafa; İskeleli, Nazan Ocak; Ağar, Erbil

2009-08-01

Some novel azo compounds were prepared by the reaction of 2-hydroxyacetophenone with aniline and its substituted derivatives. The structures of synthesized azo compounds were determined by IR, UV-Vis, 1H NMR and 13C NMR spectroscopic techniques and the structures of some of these compounds were also determined by X-ray diffraction studies. Structural analysis using IR in solid state shows that the azo form is favoured in the azo compounds whereas UV-Vis analysis of the azo compounds in solution has shown that there is a azo and ionic form. The azo compounds in the basic solvents dimethylformamide (DMF) and dimethylsulfoxide (DMSO) are both azo and ionic form while these compounds in ethyl alcohol (EtOH) and chloroform (CHCl 3) are only azo form.

Optical and UV-Aging Properties of LDH-Modified Bitumen

Directory of Open Access Journals (Sweden)

Xing Liu

2015-07-01

Full Text Available Layered double hydroxides (LDHs are an ultraviolet-light (UV resistant material. In this study, LDHs were used to modify bitumen. The optical and UV aging properties of LDHs modified bitumen were investigated. Firstly, the thin films of bitumen, with and without LDHs, were prepared. By using the UV-Vis spectrophotometer, absorbance, reflectance, and transmittance of bituminous thin film were evaluated. The morphology of LDHs-modified bitumen was observed by using fluorescence microscopy (FM. Finally, the aging resistance of LDH-modified bitumen was investigated by using the UV-aging oven. Results indicated that the LDHs, especially with 5 wt % in the bitumen, can effectively absorb and reflect the UV light and improve the UV-aging resistance of bitumen. This implied that the addition of LDHs into bitumen had the potential to prolong the service life of asphalt pavement.

Solid State Photovoltaic Research Branch

Energy Technology Data Exchange (ETDEWEB)

1990-09-01

This report summarizes the progress of the Solid State Photovoltaic Research Branch of the Solar Energy Research Institute (SERI) from October 1, 1988, through September 30,l 1989. Six technical sections of the report cover these main areas of SERIs in-house research: Semiconductor Crystal Growth, Amorphous Silicon Research, Polycrystalline Thin Films, III-V High-Efficiency Photovoltaic Cells, Solid-State Theory, and Laser Raman and Luminescence Spectroscopy. Sections have been indexed separately for inclusion on the data base.

Quantum chemical modeling of new derivatives of (E,E)-azomethines: Synthesis, spectroscopic (FT-IR, UV/Vis, polarization) and thermophysical investigations

Science.gov (United States)

Shahab, Siyamak; Sheikhi, Masoome; Filippovich, Liudmila; Anatol'evich, Dikusar Evgenij; Yahyaei, Hooriye

2017-06-01

In the present work, the molecular structures of three new azomethine dyes: N-benzylidene-4-((E)-phenyldiazenyl)aniline (PAZB-1), 2-methoxy-4-(((4-((E)- phenyldiazenyl)phenyl)imino)methyl)phenol (PAZB-2) and 2-methoxy-5-((E)-((4-((E)- phenyldiazenyl)phenyl)imino)methyl)phenol (PAZB-8) have been predicted and investigated using Density Functional Theory (DFT) in dimethylformamide (DMF). The geometries of the azomethine dyes were optimized by PBE0/6-31 + G* level of theory. The electronic spectra of these azomethine dyes in a DMF solution was carried out by TDPBE0/6-31 + G* method. After quantum-chemical calculations three new azomethine dyes for optoelectronic applications were synthesized. FT-IR spectra of the title compounds are recorded and discussed. The computed absorption spectral data of the azomethine dyes are in good agreement with the experimental data, thus allowing an assignment of the UV/Vis spectra. On the basis of polyvinyl alcohol (PVA) and the new synthesized azomethine dyes polarizing films for Visible region of spectrum were developed. The main optical parameters of polarizing PVA-films (Transmittance, Polarization Efficiency and Dichroic Ratio) have been measured and discussed. Anisotropy of thermal conductivity of the PVA-films has been studied.

PREPARATION AND CHARACTERIZATION OF SOLID ELECTROLYTES: FUEL CELL APPLICATIONS

Energy Technology Data Exchange (ETDEWEB)

Rambabu Bobba; Josef Hormes; T. Wang; Jaymes A. Baker; Donald G. Prier; Tommy Rockwood; Dinesha Hawkins; Saleem Hasan; V. Rayanki

1997-12-31

The intent of this project with Federal Energy Technology Center (FETC)/Morgantown Energy Technology Center (METC) is to develop research infrastructure conductive to Fuel Cell research at Southern University and A and M College, Baton Route. A state of the art research laboratory (James Hall No.123 and No.114) for energy conversion and storage devices was developed during this project duration. The Solid State Ionics laboratory is now fully equipped with materials research instruments: Arbin Battery Cycling and testing (8 channel) unit, Electrochemical Analyzer (EG and G PAR Model 273 and Solartron AC impedance analyzer), Fuel Cell test station (Globe Tech), Differential Scanning Calorimeter (DSC-10), Thermogravimetric Analyzer (TGA), Scanning Tunneling Microscope (STM), UV-VIS-NIR Absorption Spectrometer, Fluorescence Spectrometer, FT-IR Spectrometer, Extended X-ray Absorption Fine Structure (EXAFS) measurement capability at Center for Advanced Microstructure and Devices (CAMD- a multimillion dollar DOE facility), Glove Box, gas hood chamber, high temperature furnaces, hydraulic press and several high performance computers. IN particular, a high temperature furnace (Thermodyne 6000 furnace) and a high temperature oven were acquired through this project funds. The PI Dr. R Bobba has acquired additional funds from federal agencies include NSF-Academic Research Infrastructure program and other DOE sites. They have extensively used the multimillion dollar DOE facility ''Center'' for Advanced Microstructures and Devices (CAMD) for electrochemical research. The students were heavily involved in the experimental EXAFS measurements and made use of their DCM beamline for EXAFS research. The primary objective was to provide hands on experience to the selected African American undergraduate and graduate students in experimental energy research.The goal was to develop research skills and involve them in the Preparation and Characterization of Solid

Solid-state NMR basic principles and practice

CERN Document Server

Apperley, David C; Hodgkinson, Paul

2014-01-01

Nuclear Magnetic Resonance (NMR) has proved to be a uniquely powerful and versatile tool for analyzing and characterizing chemicals and materials of all kinds. This book focuses on the latest developments and applications for "solid-state" NMR, which has found new uses from archaeology to crystallography to biomaterials and pharmaceutical science research. The book will provide materials engineers, analytical chemists, and physicists, in and out of lab, a survey of the techniques and the essential tools of solid-state NMR, together with a practical guide on applications. In this concise introduction to the growing field of solid-state nuclear magnetic resonance spectroscopy The reader will find: * Basic NMR concepts for solids, including guidance on the spin-1/2 nuclei concept * Coverage of the quantum mechanics aspects of solid state NMR and an introduction to the concept of quadrupolar nuclei * An understanding relaxation, exchange and quantitation in NMR * An analysis and interpretation of NMR data, with e...

UV scale calibration transfer from an improved pyroelectric detector standard to field UV-A meters and 365 nm excitation sources

Science.gov (United States)

Eppeldauer, G. P.; Podobedov, V. B.; Cooksey, C. C.

2017-05-01

Calibration of the emitted radiation from UV sources peaking at 365 nm, is necessary to perform the ASTM required 1 mW/cm2 minimum irradiance in certain military material (ships, airplanes etc) tests. These UV "black lights" are applied for crack-recognition using fluorescent liquid penetrant inspection. At present, these nondestructive tests are performed using Hg-lamps. Lack of a proper standard and the different spectral responsivities of the available UV meters cause significant measurement errors even if the same UV-365 source is measured. A pyroelectric radiometer standard with spectrally flat (constant) response in the UV-VIS range has been developed to solve the problem. The response curve of this standard determined from spectral reflectance measurement, is converted into spectral irradiance responsivity with UV sources (with different peaks and distributions) without using any source standard. Using this broadband calibration method, yearly spectral calibrations for the reference UV (LED) sources and irradiance meters is not needed. Field UV sources and meters can be calibrated against the pyroelectric radiometer standard for broadband (integrated) irradiance and integrated responsivity. Using the broadband measurement procedure, the UV measurements give uniform results with significantly decreased uncertainties.

Quantum computational studies, spectroscopic (FT-IR, FT-Raman and UV-Vis) profiling, natural hybrid orbital and molecular docking analysis on 2,4 Dibromoaniline

Science.gov (United States)

Abraham, Christina Susan; Prasana, Johanan Christian; Muthu, S.; Rizwana B, Fathima; Raja, M.

2018-05-01

The research exploration will comprise of investigating the molecular structure, vibrational assignments, bonding and anti-bonding nature, nonlinear optical, electronic and thermodynamic nature of the molecule. The research is conducted at two levels: First level employs the spectroscopic techniques - FT-IR, FT-Raman and UV-Vis characterizing techniques; at second level the data attained experimentally is analyzed through theoretical methods using and Density Function Theories which involves the basic principle of solving the Schrodinger equation for many body systems. A comparison is drawn between the two levels and discussed. The probability of the title molecule being bio-active theoretically proved by the electrophilicity index leads to further property analyzes of the molecule. The target molecule is found to fit well with Centromere associated protein inhibitor using molecular docking techniques. Higher basis set 6-311++G(d,p) is used to attain results more concurrent to the experimental data. The results of the organic amine 2, 4 Dibromoaniline is analyzed and discussed.

Photoemission from solids: the transition from solid-state to atomic physics

International Nuclear Information System (INIS)

Shirley, D.A.

1980-08-01

As the photon energy is increased, photoemission from solids undergoes a slow transition from solid-state to atomic behavior. However, throughout the energy range hν = 10 to 1000 eV or higher both types of phenomena are present. Thus angle-resolved photoemission can only be understood quantitatively if each experimenter recognizes the presence of band-structure, photoelectron diffraction, and photoelectron asymmetry effects. The quest for this understanding will build some interesting bridges between solid-state and atomic physics and should also yield important new insights about the phenomena associated with photoemission

Lithium-ion transport in inorganic solid state electrolyte

International Nuclear Information System (INIS)

Gao Jian; Li Hong; Zhao Yu-Sheng; Shi Si-Qi

2016-01-01

An overview of ion transport in lithium-ion inorganic solid state electrolytes is presented, aimed at exploring and designing better electrolyte materials. Ionic conductivity is one of the most important indices of the performance of inorganic solid state electrolytes. The general definition of solid state electrolytes is presented in terms of their role in a working cell (to convey ions while isolate electrons), and the history of solid electrolyte development is briefly summarized. Ways of using the available theoretical models and experimental methods to characterize lithium-ion transport in solid state electrolytes are systematically introduced. Then the various factors that affect ionic conductivity are itemized, including mainly structural disorder, composite materials and interface effects between a solid electrolyte and an electrode. Finally, strategies for future material systems, for synthesis and characterization methods, and for theory and calculation are proposed, aiming to help accelerate the design and development of new solid electrolytes. (topical review)

Advances in Solid State Physics

CERN Document Server

Haug, Rolf

2008-01-01

The present volume 47 of the Advances in Solid State Physics contains the written version of a large number of the invited talks of the 2007 Spring Meeting of the Arbeitskreis Festkörperphysik which was held in Regensburg, Germany, from March 26 to 30, 2007 in conjunction with the 71st Annual Meeting of the Deutsche Physikalische Gesellschaft.It gives an overview of the present status of solid state physics where low-dimensional systems such as quantum dots and quantum wires are dominating. The importance of magnetic materials is reflected by the large number of contributions in the part dealing with ferromagnetic films and particles. One of the most exciting achievements of the last couple of years is the successful application of electrical contacts to and the investigation of single layers of graphene. This exciting physics is covered in Part IV of this book. Terahertz physics is another rapidly moving field which is presented here by five contributions. Achievements in solid state physics are only rarely...

Self-aligned nanocrystalline ZnO hexagons by facile solid-state and co-precipitation route

International Nuclear Information System (INIS)

Thorat, J. H.; Kanade, K. G.; Nikam, L. K.; Chaudhari, P. D.; Panmand, R. P.; Kale, B. B.

2012-01-01

In this study, we report the synthesis of well-aligned nanocrystalline hexagonal zinc oxide (ZnO) nanoparticles by facile solid-state and co-precipitation method. The co-precipitation reactions were performed using aqueous and ethylene glycol (EG) medium using zinc acetate and adipic acid to obtain zinc adipate and further decomposition at 450 °C to confer nanocrystalline ZnO hexagons. XRD shows the hexagonal wurtzite structure of the ZnO. Thermal study reveals complete formation of ZnO at 430 °C in case of solid-state method, whereas in case of co-precipitation method complete formation was observed at 400 °C. Field emission scanning electron microscope shows spherical morphology for ZnO synthesized by solid-state method. The aqueous-mediated ZnO by co-precipitation method shows rod-like morphology. These rods are formed via self assembling of spherical nanoparticles, however, uniformly dispersed spherical crystallites were seen in EG-mediated ZnO. Transmission electron microscope (TEM) investigations clearly show well aligned and highly crystalline transparent and thin hexagonal ZnO. The particle size was measured using TEM and was observed to be 50–60 nm in case of solid-state method and aqueous-mediated co-precipitation method, while 25–50 nm in case of EG-mediated co-precipitation method. UV absorption spectra showed sharp absorption peaks with a blue shift for EG-mediated ZnO, which demonstrate the mono-dispersed lower particle size. The band gap of the ZnO was observed to be 3.4 eV which is higher than the bulk, implies nanocrystalline nature of the ZnO. The photoluminescence studies clearly indicate the strong violet and weak blue emission in ZnO nanoparticles which is quite unique. The process investigated may be useful to synthesize other oxide semiconductors and transition metal oxides.

Self-aligned nanocrystalline ZnO hexagons by facile solid-state and co-precipitation route

Energy Technology Data Exchange (ETDEWEB)

Thorat, J. H. [Mahatma Phule College, Department of Chemistry (India); Kanade, K. G. [Annasaheb Awate College (India); Nikam, L. K. [B.G. College (India); Chaudhari, P. D.; Panmand, R. P.; Kale, B. B., E-mail: kbbb1@yahoo.com [Center for Materials for Electronics Technology (C-MET) (India)

2012-02-15

In this study, we report the synthesis of well-aligned nanocrystalline hexagonal zinc oxide (ZnO) nanoparticles by facile solid-state and co-precipitation method. The co-precipitation reactions were performed using aqueous and ethylene glycol (EG) medium using zinc acetate and adipic acid to obtain zinc adipate and further decomposition at 450 Degree-Sign C to confer nanocrystalline ZnO hexagons. XRD shows the hexagonal wurtzite structure of the ZnO. Thermal study reveals complete formation of ZnO at 430 Degree-Sign C in case of solid-state method, whereas in case of co-precipitation method complete formation was observed at 400 Degree-Sign C. Field emission scanning electron microscope shows spherical morphology for ZnO synthesized by solid-state method. The aqueous-mediated ZnO by co-precipitation method shows rod-like morphology. These rods are formed via self assembling of spherical nanoparticles, however, uniformly dispersed spherical crystallites were seen in EG-mediated ZnO. Transmission electron microscope (TEM) investigations clearly show well aligned and highly crystalline transparent and thin hexagonal ZnO. The particle size was measured using TEM and was observed to be 50-60 nm in case of solid-state method and aqueous-mediated co-precipitation method, while 25-50 nm in case of EG-mediated co-precipitation method. UV absorption spectra showed sharp absorption peaks with a blue shift for EG-mediated ZnO, which demonstrate the mono-dispersed lower particle size. The band gap of the ZnO was observed to be 3.4 eV which is higher than the bulk, implies nanocrystalline nature of the ZnO. The photoluminescence studies clearly indicate the strong violet and weak blue emission in ZnO nanoparticles which is quite unique. The process investigated may be useful to synthesize other oxide semiconductors and transition metal oxides.

Atomic layer deposition of lithium phosphates as solid-state electrolytes for all-solid-state microbatteries

International Nuclear Information System (INIS)

Wang, Biqiong; Liu, Jian; Sun, Qian; Li, Ruying; Sun, Xueliang; Sham, Tsun-Kong

2014-01-01

Atomic layer deposition (ALD) has been shown as a powerful technique to build three-dimensional (3D) all-solid-state microbattery, because of its unique advantages in fabricating uniform and pinhole-free thin films in 3D structures. The development of solid-state electrolyte by ALD is a crucial step to achieve the fabrication of 3D all-solid-state microbattery by ALD. In this work, lithium phosphate solid-state electrolytes were grown by ALD at four different temperatures (250, 275, 300, and 325 °C) using two precursors (lithium tert-butoxide and trimethylphosphate). A linear dependence of film thickness on ALD cycle number was observed and uniform growth was achieved at all four temperatures. The growth rate was 0.57, 0.66, 0.69, and 0.72 Å/cycle at deposition temperatures of 250, 275, 300, and 325 °C, respectively. Furthermore, x-ray photoelectron spectroscopy confirmed the compositions and chemical structures of lithium phosphates deposited by ALD. Moreover, the lithium phosphate thin films deposited at 300 °C presented the highest ionic conductivity of 1.73 × 10 −8 S cm −1 at 323 K with ∼0.51 eV activation energy based on the electrochemical impedance spectroscopy. The ionic conductivity was calculated to be 3.3 × 10 −8 S cm −1 at 26 °C (299 K). (paper)

Solid-state membrane module

Science.gov (United States)

Gordon, John Howard [Salt Lake City, UT; Taylor, Dale M [Murray, UT

2011-06-07

Solid-state membrane modules comprising at least one membrane unit, where the membrane unit has a dense mixed conducting oxide layer, and at least one conduit or manifold wherein the conduit or manifold comprises a dense layer and at least one of a porous layer and a slotted layer contiguous with the dense layer. The solid-state membrane modules may be used to carry out a variety of processes including the separating of any ionizable component from a feedstream wherein such ionizable component is capable of being transported through a dense mixed conducting oxide layer of the membrane units making up the membrane modules. For ease of construction, the membrane units may be planar.

Fabrication of transparent cellulose acetate/graphene oxide nanocomposite film for UV shielding

Energy Technology Data Exchange (ETDEWEB)

Jahan, Nusrat; Khan, Wasi, E-mail: wasiamu@gmail.com; Azam, Ameer; Naqvi, A. H. [Department of Applied Physics, Z.H. College of Engineering & Technology, Aligarh Muslim University, Aligarh - 202002 (India)

2016-05-23

In this work, we have fabricated transparent cellulose acetate/graphene oxide nanocomposite (CAGONC) films for ultraviolet radiations (UVR) shielding. Graphene oxide (GO) was synthesized by modified Hummer’s method and CAGONC films were fabricated by solvent casting method. The films were analyzed using characterization techniques like x-ray diffraction (XRD), energy dispersive x-ray (EDX) equipped scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and ultra-violet visible (UV-VIS) spectroscopy. Four films were prepared by varying the wt% of GO (0.1wt%, 0.2wt% and 0.3wt%) with respect to cellulose acetate (CA). UV-vis measurements exhibit optical transparency in the range of 76-99% for visible light while ultra-violet radiation was substantially shielded.

Oriented solid-state NMR spectrosocpy

DEFF Research Database (Denmark)

Bertelsen, Kresten

This thesis is concerned with driving forward oriented solid-state NMR spectroscopy as a viable technique for studying peptides in membrane bilayers. I will show that structural heterogeneity is an intrinsic part of the peptide/lipid system and that NMR can be used to characterize static...... and dynamic structural features of the peptides and its local surroundings. In fact one need to take into account the dynamical features of the system in order to correctly predict the structure from oriented solid-state NMR spectra.      ...

Enhanced Chemical Cleaning: Effectiveness Of The UV Lamp To Decompose Oxalates

International Nuclear Information System (INIS)

Ketusky, E.; Huff, T.; Sudduth, C.

2010-01-01

Enhanced Chemical Cleaning is a new process scheduled to begin cleaning Savannah River Site High Level Waste Tanks in 2012. It is an improvement over the current chemical cleaning method, in that it minimizes downstream impacts on the High Level Waste System. It is based on a state of the art scale removal process used on the secondary side of nuclear power plants, with modifications to accommodate the unique constraints created by the tanks. Both Enhanced Chemical Cleaning and the scale removal process are founded on dissolving metal oxides/hydroxides using oxalic acid, with subsequent oxalate decomposition via hydroxylation using ozone or peroxide, and UV light as a catalyst. A divergence Enhanced Chemical Cleaning has from nuclear power scale removal is the significantly increased solids concentration during oxalate decomposition. These solids can limit the ability of the UV light to create hydroxyl radicals, either by limiting the ability of the light to penetrate through the solution, or by increasing the fouling rate on the UV light. Both will decrease the overall catalytic effectiveness, thereby decreasing the concentration of formed hydroxyl radicals. The hydroxyl radicals are the driving force behind the oxalate decomposition. To understand the impact of increased solids, testing was performed using a medium pressure UV light inside an ozone supplied Oxalate Decomposition Reactor. Using a dissolved metal sludge simulant with an initial oxalate concentration greater than 12,000 ppm, and an initial pH of about 2.0, the spent acid solution was recirculated through the reactor, while the UV light was allowed to foul. For the first few hours, the oxalate decomposition rate was about 1,300 ppm/hour. After about 3 hours, enough time for the UV lamp to foul, the oxalate decomposition rate decreased to about 500 ppm/hour. The decomposition rate then remained roughly constant for the next 16 hours. Overall, testing showed that the oxalate destruction rate decreased

Solid State Lighting Reliability Components to Systems

CERN Document Server

Fan, XJ

2013-01-01

Solid State Lighting Reliability: Components to Systems begins with an explanation of the major benefits of solid state lighting (SSL) when compared to conventional lighting systems including but not limited to long useful lifetimes of 50,000 (or more) hours and high efficacy. When designing effective devices that take advantage of SSL capabilities the reliability of internal components (optics, drive electronics, controls, thermal design) take on critical importance. As such a detailed discussion of reliability from performance at the device level to sub components is included as well as the integrated systems of SSL modules, lamps and luminaires including various failure modes, reliability testing and reliability performance. This book also: Covers the essential reliability theories and practices for current and future development of Solid State Lighting components and systems Provides a systematic overview for not only the state-of-the-art, but also future roadmap and perspectives of Solid State Lighting r...

Solid state multinuclear NMR. A versatile tool for studying the reactivity of solid systems

Energy Technology Data Exchange (ETDEWEB)

MacKenzie, Kenneth J.D. [MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington, P.O. Box 600, Wellington (New Zealand)

2004-08-31

Traditionally, X-ray powder diffraction has been a favoured method for studying chemical reactions in the solid state, but the increasing importance of energy-efficient synthesis methods for solids (e.g. sol-gel synthesis, mechanochemical synthesis) has led to the need for an analytical method not dependent on long-range structural periodicity. Multinuclear solid state nuclear magnetic resonance (NMR) represents a technique which is equally applicable to amorphous or crystalline solids, and is now used in increasing numbers of solid state studies.This paper briefly outlines the principles and practical details of this powerful technique and gives examples of its use in solid-state chemistry, particularly in very recent studies of mechanochemical synthesis of advanced sialon ceramics. The temperature at which these technically important silicon aluminium oxynitride compounds are formed can be significantly lowered by high-energy grinding of their components to produce X-ray amorphous precursors. Solid-state NMR has been used to provide detailed information which could not have been obtained by any other means about the chemical environment of the Si and Al atoms in these amorphous precursors, and the various atomic movements undergone as they crystallise to the final product.

Solid state ionics: a Japan perspective

Science.gov (United States)

Yamamoto, Osamu

2017-12-01

The 70-year history of scientific endeavor of solid state ionics research in Japan is reviewed to show the contribution of Japanese scientists to the basic science of solid state ionics and its applications. The term 'solid state ionics' was defined by Takehiko Takahashi of Nagoya University, Japan: it refers to ions in solids, especially solids that exhibit high ionic conductivity at a fairly low temperature below their melting points. During the last few decades of exploration, many ion conducting solids have been discovered in Japan such as the copper-ion conductor Rb4Cu16I7Cl13, proton conductor SrCe1-xYxO3, oxide-ion conductor La0.9Sr0.9Ga0.9Mg0.1O3, and lithium-ion conductor Li10GeP2S12. Rb4Cu16I7Cl13 has a conductivity of 0.33 S cm-1 at 25 °C, which is the highest of all room temperature ion conductive solid electrolytes reported to date, and Li10GeP2S12 has a conductivity of 0.012 S cm-1 at 25 °C, which is the highest among lithium-ion conductors reported to date. Research on high-temperature proton conducting ceramics began in Japan. The history, the discovery of novel ionic conductors and the story behind them are summarized along with basic science and technology.

The precipitation synthesis of broad-spectrum UV absorber nanoceria

International Nuclear Information System (INIS)

Nurhasanah, Iis; Sutanto, Heri; Puspaningrum, Nurul Wahyu

2013-01-01

In this paper the possibility of nanoceria as broad-spectrum UV absorber was evaluated. Nanoceria were synthesized by precipitation process from cerium nitrate solution and ammonium hydroxide as precipitant agent. Isopropanol was mixed with water as solvent to prevent hard agglomeration. The structure of resulting nanoceria was characterized by x-ray diffractometer (XRD). The transparency in the visible light and efficiency of protection in UV A region were studied using ultraviolet-visible (UV - Vis) spectrophotometer. The results show that nanoceria possess good tranparency in visible light and high UV light absorption. The critical absorption wavelenght of 368 nm was obtained which is desirable for excellent broad-spectrum protection absorbers. Moreover, analysis of photodegradation nanoceria to methylene blue solution shows poor photocatalytic activity. It indicates that nanoceria suitable for used as UV absorber in personal care products

Introduction to solid state electronics

CERN Document Server

Wang, FFY

1989-01-01

This textbook is specifically tailored for undergraduate engineering courses offered in the junior year, providing a thorough understanding of solid state electronics without relying on the prerequisites of quantum mechanics. In contrast to most solid state electronics texts currently available, with their generalized treatments of the same topics, this is the first text to focus exclusively and in meaningful detail on introductory material. The original text has already been in use for 10 years. In this new edition, additional problems have been added at the end of most chapters. These proble

Solid state physics an introduction

CERN Document Server

Hofmann, Philip

2015-01-01

A must-have textbook for any undergraduate studying solid state physics. This successful brief course in solid state physics is now in its second edition. The clear and concise introduction not only describes all the basic phenomena and concepts, but also such advanced issues as magnetism and superconductivity. Each section starts with a gentle introduction, covering basic principles, progressing to a more advanced level in order to present a comprehensive overview of the subject. The book is providing qualitative discussions that help undergraduates understand concepts even if they can?t foll

Characterisation of PDO olive oil Chianti Classico by non-selective (UV-visible, NIR and MIR spectroscopy) and selective (fatty acid composition) analytical techniques

Energy Technology Data Exchange (ETDEWEB)

Casale, M., E-mail: monica@dictfa.unige.it [Universita degli Studi di Genova, Department of Chemistry and Food and Pharmaceutical Technologies, Via Brigata Salerno 13, I-16147, Genoa (Italy); Oliveri, P.; Casolino, C. [Universita degli Studi di Genova, Department of Chemistry and Food and Pharmaceutical Technologies, Via Brigata Salerno 13, I-16147, Genoa (Italy); Sinelli, N. [Universita degli Studi di Milano, Department of Food Science and Technology, Via Celoria, 2 - I-20133 Milan (Italy); Zunin, P.; Armanino, C.; Forina, M.; Lanteri, S. [Universita degli Studi di Genova, Department of Chemistry and Food and Pharmaceutical Technologies, Via Brigata Salerno 13, I-16147, Genoa (Italy)

2012-01-27

Highlights: Black-Right-Pointing-Pointer Characterisation of the Italian PDO extra virgin olive oil Chianti Classico. Black-Right-Pointing-Pointer Comparison between non-selective (UV-vis, NIR and MIR spectroscopy) and selective (fatty acid composition) analytical techniques. Black-Right-Pointing-Pointer Synergy among spectroscopic techniques, by the fusion of the respective spectra. Black-Right-Pointing-Pointer Prediction of the content of oleic and linoleic acids in the olive oils. - Abstract: An authentication study of the Italian PDO (protected designation of origin) extra virgin olive oil Chianti Classico was performed; UV-visible (UV-vis), Near-Infrared (NIR) and Mid-Infrared (MIR) spectroscopies were applied to a set of samples representative of the whole Chianti Classico production area. The non-selective signals (fingerprints) provided by the three spectroscopic techniques were utilised both individually and jointly, after fusion of the respective profile vectors, in order to build a model for the Chianti Classico PDO olive oil. Moreover, these results were compared with those obtained by the gas chromatographic determination of the fatty acids composition. In order to characterise the olive oils produced in the Chianti Classico PDO area, UNEQ (unequal class models) and SIMCA (soft independent modelling of class analogy) were employed both on the MIR, NIR and UV-vis spectra, individually and jointly, and on the fatty acid composition. Finally, PLS (partial least square) regression was applied on the UV-vis, NIR and MIR spectra, in order to predict the content of oleic and linoleic acids in the extra virgin olive oils. UNEQ, SIMCA and PLS were performed after selection of the relevant predictors, in order to increase the efficiency of both classification and regression models. The non-selective information obtained from UV-vis, NIR and MIR spectroscopy allowed to build reliable models for checking the authenticity of the Italian PDO extra virgin olive oil

Ultrasonic methods in solid state physics

CERN Document Server

Truell, John; Elbaum, Charles

1969-01-01

Ultrasonic Methods in Solid State Physics is devoted to studies of energy loss and velocity of ultrasonic waves which have a bearing on present-day problems in solid-state physics. The discussion is particularly concerned with the type of investigation that can be carried out in the megacycle range of frequencies from a few megacycles to kilomegacycles; it deals almost entirely with short-duration pulse methods rather than with standing-wave methods. The book opens with a chapter on a classical treatment of wave propagation in solids. This is followed by separate chapters on methods and techni

Persistent luminescence and thermoluminescence of UV/VIS -irradiated SrAl2O4: Eu2+, Dy3+ phosphor

International Nuclear Information System (INIS)

Pereyda-Pierre, C.; Meléndrez, R.; García, R.; Pedroza-Montero, M.; Barboza-Flores, M.

2011-01-01

The persistent luminescence and thermoluminescence properties of SrAl 2 O 4 : Eu 2+ , Dy 3+ phosphors excited with UV–VIS light in the 200–500 nm region were investigated. The thermoluminescence glow curve was found to be composed of peaks around 70, 125 and 245 °C. The persistent luminescence and thermoluminescence excitation spectra exhibited a broad band around 300–500 nm centered at 400 and 420 nm respectively. A linear behavior of the integrated thermoluminescence intensity and persistent luminescence versus irradiation time was found for the first 60 s. The charge detrapping from the 70 °C trapping levels was the major contributor to the observed persistent luminescence at room temperature. The SrAl 2 O 4 : Eu 2+ , Dy 3+ phosphors have suitable properties to be applied as storage and persistent luminescence UV–VIS irradiation dose phosphor. -- Highlights: ► SrAl 2 O 4 :Eu 2+ , Dy 3+ persistent luminescence and thermoluminescence was measured. ► The phosphor was irradiated with UV–VIS photons in the 200–500 nm wavelength range. ► SrAl 2 O 4 :Eu 2+ , Dy 3+ behaves adequately as persistent and storage UV–VIS dosimeter. ► The persistent luminescence dosimetry does not require heat or light stimulation.

Design of geometry, synthesis, spectroscopic (FT-IR, UV/Vis, excited state, polarization) and anisotropy (thermal conductivity and electrical) properties of new synthesized derivatives of (E,E)-azomethines in colored stretched poly (vinyl alcohol) matrix

Science.gov (United States)

Shahab, Siyamak; Sheikhi, Masoome; Filippovich, Liudmila; Dikusar, Evgenij; Yahyaei, Hooriye; Kumar, Rakesh; Khaleghian, Mehrnoosh

2018-04-01

In the present work, the molecular structures of two new azomethine dyes: have been predicted and investigated using Density Functional Theory (DFT) in dimethylformamide (DMF). The geometries of the azomethine dyes were optimized by B3LYP/6-31+G* level of theory. The electronic spectra of these azomethine dyes in a DMF solvent was carried out by using TD-B3LYP/6-31+G* method. After quantum-chemical calculations two new azomethine dyes for optoelectronic applications were synthesized. FT-IR spectra of the title compounds are recorded and discussed. The computed absorption spectral data of the azomethine dyes are in good agreement with the experimental data, thus allowing an assignment of the UV/Vis spectra. On the basis of polyvinyl alcohol (PVA) and the new synthesized azomethine dyes polarizing films for visible region of spectrum were developed. The main optical parameters of the polarizing PVA-films (Transmittance, Polarization Efficiency and Dichroic Ratio) have been measured and discussed. Anisotropy of thermal and electrical conductivity of the PVA-films have been studied and explained.

Elaboration of Langmuir-Blodgett films of oligothiophenes derivatives for solid state polymerisation

International Nuclear Information System (INIS)

Isz, Sandrine

1995-01-01

Molecular electronics requires the elaboration of highly organised conductive architectures, and this research thesis addresses the fabrication of oriented conductive molecular wires. Precursors can be oriented by using the Langmuir-Blodgett technique. Synthesized molecules are oligothiophenes. After a UV-visible study in solution, these molecules have been tested under the form of Langmuir-Blodgett films. Their behaviour at the air-water interface has been characterized by using various techniques (compression isothermal, Brewster angle microscope, transmission electronic microscope, atomic force microscope) to check that higher oligothiophenes are forming a molecular film. Crystal structure reveals an almost vertical orientation of molecules at the water surface. A solid state coupling between these organised molecules has been attempted by electrochemical, thermal, and chemical ways [fr

Optoelectronic properties of a novel fluorene derivative for organic light-emitting diode

Energy Technology Data Exchange (ETDEWEB)

Yu, Junsheng; Lou, Shuangling; Qian, Jincheng; Jiang, Yadong [University of Electronic Science and Technology of China (UESTC), State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, Chengdu (China); Zhang, Qing [Shanghai Jiaotong University, Department of Polymer Science, School of Chemistry and Chemical Technology, Shanghai (China)

2009-03-15

We report the optoelectronic properties of a novel fluorene derivative of 6,6'-(9H-fluoren-9,9-diyl)bis(2,3-bis (9,9-dihexyl-9H-fluoren-2-yl)quinoxaline) (BFLBBFLYQ) used for organic light-emitting diode. UV-Vis absorption, photoluminescence (PL) and electroluminescence (EL) spectra of BFLBBFLYQ and the blend doped with N,N'-biphenyl-N,N'-bis-(3-methylphenyl)-1,1'-biphenyl-4,4'-di- amine (TPD) in solid state and in solution were investigated. The results showed that BFLBBFLYQ had a PL peak at 451 nm in solid and solution states and an EL peak at 483 nm with a broad emission band, resulting from fluorenone defects. Exciplex emission was observed in BFLBBFLYQ-TPD blend solid state with a green emission peaking at 530 nm. Also the blend in solution showed solvatochromism in polarity solvent upon UV irradiation. A new absorption band appeared at around 470 nm of BFLBBFLYQ-TPD blend in chloroform solution, and disappeared when diluted in absorption spectrum. Meanwhile, a low energy emission band from 530 to 580 nm appeared and increased with material concentration and UV irradiation time. (orig.)

Silicon solid state devices and radiation detection

CERN Document Server

Leroy, Claude

2012-01-01

This book addresses the fundamental principles of interaction between radiation and matter, the principles of working and the operation of particle detectors based on silicon solid state devices. It covers a broad scope with respect to the fields of application of radiation detectors based on silicon solid state devices from low to high energy physics experiments including in outer space and in the medical environment. This book covers stateof- the-art detection techniques in the use of radiation detectors based on silicon solid state devices and their readout electronics, including the latest developments on pixelated silicon radiation detector and their application.

Four-Component Damped Density Functional Response Theory Study of UV/Vis Absorption Spectra and Phosphorescence Parameters of Group 12 Metal-Substituted Porphyrins.

Science.gov (United States)

Fransson, Thomas; Saue, Trond; Norman, Patrick

2016-05-10

The influences of group 12 (Zn, Cd, Hg) metal-substitution on the valence spectra and phosphorescence parameters of porphyrins (P) have been investigated in a relativistic setting. In order to obtain valence spectra, this study reports the first application of the damped linear response function, or complex polarization propagator, in the four-component density functional theory framework [as formulated in Villaume et al. J. Chem. Phys. 2010 , 133 , 064105 ]. It is shown that the steep increase in the density of states as due to the inclusion of spin-orbit coupling yields only minor changes in overall computational costs involved with the solution of the set of linear response equations. Comparing single-frequency to multifrequency spectral calculations, it is noted that the number of iterations in the iterative linear equation solver per frequency grid-point decreases monotonously from 30 to 0.74 as the number of frequency points goes from one to 19. The main heavy-atom effect on the UV/vis-absorption spectra is indirect and attributed to the change of point group symmetry due to metal-substitution, and it is noted that substitutions using heavier atoms yield small red-shifts of the intense Soret-band. Concerning phosphorescence parameters, the adoption of a four-component relativistic setting enables the calculation of such properties at a linear order of response theory, and any higher-order response functions do not need to be considered-a real, conventional, form of linear response theory has been used for the calculation of these parameters. For the substituted porphyrins, electronic coupling between the lowest triplet states is strong and results in theoretical estimates of lifetimes that are sensitive to the wave function and electron density parametrization. With this in mind, we report our best estimates of the phosphorescence lifetimes to be 460, 13.8, 11.2, and 0.00155 s for H2P, ZnP, CdP, and HgP, respectively, with the corresponding transition

Analysis of UV-excited fluorochromes by flow cytometry using near-ultraviolet laser diodes.

Science.gov (United States)

Telford, William G

2004-09-01

Violet laser diodes have become common and reliable laser sources for benchtop flow cytometers. While these lasers are very useful for a variety of violet and some ultraviolet-excited fluorochromes (e.g., DAPI), they do not efficiently excite most UV-stimulated probes. In this study, the next generation of InGaN near-UV laser diodes (NUVLDs) emitting in the 370-375-nm range have been evaluated as laser sources for cuvette-based flow cytometers. Several NUVLDs, ranging in wavelength from 370 to 374 nm and in power level from 1.5 to 10 mW, were mounted on a BD Biosciences LSR II and evaluated for their ability to excite cells labeled with the UV DNA binding dye DAPI, several UV phenotyping fluorochromes (including Alexa Fluor 350, Marina Blue, and quantum dots), and the fluorescent calcium chelator indo-1. NUVLDs at the 8-10-mW power range gave detection sensitivity levels comparable to more powerful solid-state and ion laser sources, using low-fluorescence microsphere beads as measurement standards. NUVLDs at all tested power levels allowed extremely high-resolution DAPI cell cycle analysis, and sources in the 8-10-mW power range excited Alexa Fluor 350, Marina Blue, and a variety of quantum dots at virtually the same signal-to-noise ratios as more powerful UV sources. These evaluations indicate that near-UV laser diodes installed on a cuvette-based flow cytometer performed nearly as well as more powerful solid-state UV lasers on the same instrumentation, and comparably to more powerful ion lasers on a jet-in-air system, and. Despite their limited power, integration of these small and inexpensive lasers into benchtop flow cytometers should allow the use of flow cytometric applications requiring UV excitation on a wide variety of instruments. Copyright 2004 Wiley-Liss, Inc.

Redox equilibrium of U4+/U3+ in molten NaCl-2CsCl by UV-Vis spectrophotometry and cyclic voltammetry

International Nuclear Information System (INIS)

Nagai, Takayuki; Uehara, Akihiro; Fujii, Toshiyuki; Shirai, Osamu; Yamana, Hajimu; Sato, Nobuaki

2005-01-01

In order to investigate the redox equilibrium of uranium ions in molten NaCl-2CsCl, UV-Vis absorption spectro-photometry measurements were performed for U 4+ and U 3+ in molten NaCl-2CsCl at 923 K under simultaneous electrolytic control of their ratio. Prominent absorption bands at 480 and 570 nm were assigned to U 3+ , and their molar absorptivities were determined to be 1,260±42 and 963±32 mol -1 ·l·cm -1 respectively. From the dependence of the rest potential of the melt on the spectrophotometrically determined ratio of [U 4+ ]/[U 3+ ], the standard redox potential of the couple U 4+ /U 3+ at 923 K was determined to be -1.481±0.004 V vs. Cl 2 /Cl - . Cyclic voltammetry measurements were carried out for the couple U 4+ /U 3+ , and the results agreed well with this standard redox potential value. By the results of cyclic voltammetry, a temperature dependence of the standard redox potential was found to be -2.094+6.639 x 10 -4 T (T=823-923K). (author)

Solid state synthesis of water-dispersible silicon nanoparticles from silica nanoparticles

International Nuclear Information System (INIS)

Kravitz, Keren; Kamyshny, Alexander; Gedanken, Aharon; Magdassi, Shlomo

2010-01-01

A solid state synthesis for obtaining nanocrystalline silicon was performed by high temperature reduction of commercial amorphous nanosilica with magnesium powder. The obtained silicon powder contains crystalline silicon phase with lattice spacings characteristic of diamond cubic structure (according to high resolution TEM), and an amorphous phase. In 29 Si CP MAS NMR a broad multicomponent peak corresponding to silicon is located at -61.28 to -69.45 ppm, i.e. between the peaks characteristic of amorphous and crystalline Si. The powder has displayed red luminescence while excited under UV illumination, due to quantum confinement within the nanocrystals. The silicon nanopowder was successfully dispersed in water containing poly(vinyl alcohol) as a stabilizing agent. The obtained dispersion was also characterized by red photoluminescence with a band maximum at 710 nm, thus enabling future functional coating applications. - Graphical abstract: High temperature reduction of amorphous nanosilica with magnesium powder results in the formation of powder containing crystalline silicon phase The powder displays red luminescence while excited under UV illumination, due to quantum confinement within the Si nanocrystals, and can be successfully dispersed in water containing poly(vinyl alcohol) as a stabilizing agent. The obtained dispersion was also characterized by red photoluminescence, thus enabling future functional coating applications.

Solid state laser technology - A NASA perspective

Science.gov (United States)

Allario, F.

1985-01-01

NASA's program for developing solid-state laser technology and applying it to the Space Shuttle and Space Platform is discussed. Solid-state lasers are required to fulfill the Earth Observation System's requirements. The role of the Office of Aeronautics and Space Technology in developing a NASA tunable solid-state laser program is described. The major goals of the program involve developing a solid-state pump laser in the green, using AlGaAs array technology, pumping a Nd:YAG/SLAB crystal or glass, and fabricating a lidar system, with either a CO2 laser at 10.6 microns or a Nd:YAG laser at 1.06 microns, to measure tropospheric winds to an accuracy of + or - 1 m/s and a vertical resolution of 1 km. The procedures to be followed in order to visualize this technology plan include: (1) material development and characterization, (2) laser development, and (3) implementation of the lasers.

Impurity profiling of liothyronine sodium by means of reversed phase HPLC, high resolution mass spectrometry, on-line H/D exchange and UV/Vis absorption.

Science.gov (United States)

Ruggenthaler, M; Grass, J; Schuh, W; Huber, C G; Reischl, R J

2017-09-05

For the first time, a comprehensive investigation of the impurity profile of the synthetic thyroid API (active pharmaceutical ingredient) liothyronine sodium (LT 3 Na) was performed by using reversed phase HPLC and advanced structural elucidation techniques including high resolution tandem mass spectrometry (HRMS/MS) and on-line hydrogen-deuterium (H/D) exchange. Overall, 39 compounds were characterized and 25 of these related substances were previously unknown to literature. The impurity classification system recently developed for the closely related API levothyroxine sodium (LT 4 Na) could be applied to the newly characterized liothyronine sodium impurities resulting in a wholistic thyroid API impurity classification system. Furthermore, the mass-spectrometric CID-fragmentation of specific related substances was discussed and rationalized by detailed fragmentation pathways. Moreover, the UV/Vis absorption characteristics of the API and selected impurities were investigated to corroborate chemical structure assignments derived from MS data. Copyright © 2017 Elsevier B.V. All rights reserved.

Impact of Ge4+ Ion as Structural Dopant of Ti4+ in Anatase: Crystallographic Translation, Photocatalytic Behavior, and Efficiency under UV and VIS Irradiation

Directory of Open Access Journals (Sweden)

Václav Štengl

2012-01-01

Full Text Available Nanometric particles of germanium-doped TiO2 were prepared by homogeneous hydrolysis of TiOSO4 and GeCl4 in an aqueous solution using urea as the precipitation agent. Structural evolution during heating of these starting Ge-Ti oxide powders was studied by X-ray diffraction (XRD and high-temperature X-ray powder diffraction (HTXRD. The morphology and microstructure changes were monitored by means of scanning electron microscopy (SEM, Raman and infrared spectroscopy (IR, specific surface area (BET, and porosity determination (BJH. The photocatalytic activity of all samples was determined by decomposition of Orange II dye under irradiation at 365 nm and 400 nm. Moderate doping with concentration upto value 2.05 wt.% positively influences azo dye degradation under UV and Vis light. Further improvement cannot be achieved by higher Ge doping. Effect of the annealing (200, 400, and 700°C on photocatalysis and other properties has been assessed.

Photoexcited singlet and triplet states of a UV absorber ethylhexyl methoxycrylene.

Science.gov (United States)

Kikuchi, Azusa; Hata, Yuki; Kumasaka, Ryo; Nanbu, Yuichi; Yagi, Mikio

2013-01-01

The excited states of UV absorber, ethylhexyl methoxycrylene (EHMCR) have been studied through measurements of UV absorption, fluorescence, phosphorescence and electron paramagnetic resonance (EPR) spectra in ethanol. The energy levels of the lowest excited singlet (S1) and triplet (T1) states of EHMCR were determined. The energy levels of the S1 and T1 states of EHMCR are much lower than those of photolabile 4-tert-butyl-4'-methoxydibenzoylmethane. The energy levels of the S1 and T1 states of EHMCR are lower than those of octyl methoxycinnamate. The weak phosphorescence and EPR B(min) signals were observed and the lifetime was estimated to be 93 ms. These facts suggest that the significant proportion of the S1 molecules undergoes intersystem crossing to the T1 state, and the deactivation process from the T1 state is predominantly radiationless. The photostability of EHMCR arises from the (3)ππ* character in the T1 state. The zero-field splitting (ZFS) parameter in the T1 state is D** = 0.113 cm(-1). © 2012 The Authors Photochemistry and Photobiology © 2012 The American Society of Photobiology.

Thermal transformation of bioactive caffeic acid on fumed silica seen by UV-Vis spectroscopy, thermogravimetric analysis, temperature programmed desorption mass spectrometry and quantum chemical methods.

Science.gov (United States)

Kulik, Tetiana V; Lipkovska, Natalia O; Barvinchenko, Valentyna M; Palyanytsya, Borys B; Kazakova, Olga A; Dudik, Olesia O; Menyhárd, Alfréd; László, Krisztina

2016-05-15

Thermochemical studies of hydroxycinnamic acid derivatives and their surface complexes are important for the pharmaceutical industry, medicine and for the development of technologies of heterogeneous biomass pyrolysis. In this study, structural and thermal transformations of caffeic acid complexes on silica surfaces were studied by UV-Vis spectroscopy, thermogravimetric analysis, temperature programmed desorption mass spectrometry (TPD MS) and quantum chemical methods. Two types of caffeic acid surface complexes are found to form through phenolic or carboxyl groups. The kinetic parameters of the chemical reactions of caffeic acid on silica surface are calculated. The mechanisms of thermal transformations of the caffeic chemisorbed surface complexes are proposed. Thermal decomposition of caffeic acid complex chemisorbed through grafted ester group proceeds via three parallel reactions, producing ketene, vinyl and acetylene derivatives of 1,2-dihydroxybenzene. Immobilization of phenolic acids on the silica surface improves greatly their thermal stability. Copyright © 2016 Elsevier Inc. All rights reserved.

Colloidal silver nanoparticles prepared by UV-light induced citrate reduction technique for the quantitative detection of uric acid

Science.gov (United States)

Maity, Anupam; Panda, Sovan Kumar

2018-04-01

Reddish-yellow color colloid consisting of silver nanoparticles (Ag NPs) has been synthesized by reducing aqueous AgNO3 solution by photo-induced citrate reduction technique under UV light. As prepared colloid exhibits single and intense plasmonic absorption peak in the violet region of the visible spectra with the peak centered at 405 nm. The NPs are fine and spherical with diameter ranging from 5 to 10 nm. These colloidal NPs have been used for the quantitative detection of uric acid by UV-VIS spectroscopy. A linear red shifting of the characteristics Plasmonic absorption peak of Ag NPs is observed with uric acid concentration. Uric acid can be detected by UV-VIS spectroscopy down to 5 nM limit using the prepared colloid.

Solid state track detectors

International Nuclear Information System (INIS)

Reuther, H.

1976-11-01

This paper gives a survey of the present state of the development and the application of solid state track detectors. The fundamentals of the physical and chemical processes of the track formation and development are explained, the different detector materials and their registration characteristics are mentioned, the possibilities of the experimental practice and the most variable applications are discussed. (author)

Monolithic solid-state lasers for spaceflight

Science.gov (United States)

Krainak, Michael A.; Yu, Anthony W.; Stephen, Mark A.; Merritt, Scott; Glebov, Leonid; Glebova, Larissa; Ryasnyanskiy, Aleksandr; Smirnov, Vadim; Mu, Xiaodong; Meissner, Stephanie; Meissner, Helmuth

2015-02-01

A new solution for building high power, solid state lasers for space flight is to fabricate the whole laser resonator in a single (monolithic) structure or alternatively to build a contiguous diffusion bonded or welded structure. Monolithic lasers provide numerous advantages for space flight solid-state lasers by minimizing misalignment concerns. The closed cavity is immune to contamination. The number of components is minimized thus increasing reliability. Bragg mirrors serve as the high reflector and output coupler thus minimizing optical coatings and coating damage. The Bragg mirrors also provide spectral and spatial mode selection for high fidelity. The monolithic structure allows short cavities resulting in short pulses. Passive saturable absorber Q-switches provide a soft aperture for spatial mode filtering and improved pointing stability. We will review our recent commercial and in-house developments toward fully monolithic solid-state lasers.

Luminescence characterization of sol-gel derived Pr{sup 3+} doped NaGd(WO{sub 4}){sub 2} phosphors for solid state lighting applications

Energy Technology Data Exchange (ETDEWEB)

Durairajan, A., E-mail: durairajan.a@gmail.com [Crystal Growth Centre, Anna University, Chennai, 600025 (India); I3N-Aveiro, Department of Physics, University of Aveiro, Aveiro, 3810 193 (Portugal); Thangaraju, D. [Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Hamamatsu, Shizuoka, 432-8011 (Japan); Moorthy Babu, S. [Crystal Growth Centre, Anna University, Chennai, 600025 (India); Valente, M.A. [I3N-Aveiro, Department of Physics, University of Aveiro, Aveiro, 3810 193 (Portugal)

2016-08-15

In the present work, xPr{sup 3+}:NaGd(WO{sub 4}){sub 2} (0.5 ≤ x ≤ 5.0 mol%) sub-micron phosphors were synthesised by sol-gel method. Low cost precursors of metal nitrates and low temperature thermal treatment was used compared to conventional solid state reaction. The formation of highly crystalline phosphors with tetragonal structure was confirmed by XRD and increase of Pr{sup 3+} ions content in host matrix leads to expansion of the unit cell volume. The surface morphology, size and particle distribution of the phosphors were observed by field emission scanning electron microscopy (FE-SEM). A rectangular shape particle with a size distribution ranging from 400 to 600 nm and tightly packed surface was seen in FE-SEM micrographs. The various internal and external phonon modes vibration corresponding to double tungstate structure was observed in Raman spectra. The optical properties of the synthesised phosphors were explored by ultraviolet visible (UV–Vis) absorption in diffuse reflectance and photoluminescence (PL) measurements. UV–Vis measurements distinguished the host and Pr{sup 3+} absorption and also reveal an increase in optical band gap values with an increase of Pr{sup 3+}. The PL measurements show various emissions from green and red regions under 450 nm. The maximum intensity emission at 489 nm is due to {sup 3}P{sub 0} → {sup 3}H{sub 4} transition of Pr{sup 3+}. From the maximum emission the critical doping concentration was calculated to be at 3.5 mol% and critical distance between two adjacent Pr{sup 3+} ions as 20.43 Å. - Highlights: • A sol-gel method was used to prepare Pr{sup 3+} doped NaGd(WO{sub 4}){sub 2} at low temperature. • Structural, spectroscopic, morphological, and optical and luminescence properties were studied. • The praseodymium ions are in trivalent state, the site symmetry is distorted and S{sub 4} local symmetry with Na{sup +} ions. • Strong green emission was observed under UV and visible excitation.

Study on activities of vanadium (IV/V) doped TiO2(R) nanorods induced by UV and visible light

International Nuclear Information System (INIS)

Li, Li; Liu Chunyan; Liu Yun

2009-01-01

Vanadium (IV/V) doped rutile TiO 2 naonorods had been successfully synthesized through a single step hydrothermal method. The photocatalyst was characterized by transmission electron microscopy (TEM), selected area electron diffraction (SAED), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), UV-vis diffusive reflectance spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS). The results showed that the doping of V ions had significant influence on the band gap energy and the surface state of TiO 2 . The photo-activities of the new catalysts were investigated under ultraviolet (UV) and visible light. The UV-photocatalytic activity of the as-prepared catalysts was hardly influenced by doping V ions; while under visible light, the samples with 1 wt% and 0.1 wt% V exhibited enhanced activity to the oxidation of methylene blue (MB) and the reduction of Cr (VI), respectively

Solid state physics

CERN Document Server

Grosso, Giuseppe

2013-01-01

Solid State Physics is a textbook for students of physics, material science, chemistry, and engineering. It is the state-of-the-art presentation of the theoretical foundations and application of the quantum structure of matter and materials. This second edition provides timely coverage of the most important scientific breakthroughs of the last decade (especially in low-dimensional systems and quantum transport). It helps build readers' understanding of the newest advances in condensed matter physics with rigorous yet clear mathematics. Examples are an integral part of the text, carefully de

Characterisation of PDO olive oil Chianti Classico by non-selective (UV-visible, NIR and MIR spectroscopy) and selective (fatty acid composition) analytical techniques.

Science.gov (United States)

Casale, M; Oliveri, P; Casolino, C; Sinelli, N; Zunin, P; Armanino, C; Forina, M; Lanteri, S

2012-01-27

An authentication study of the Italian PDO (protected designation of origin) extra virgin olive oil Chianti Classico was performed; UV-visible (UV-vis), Near-Infrared (NIR) and Mid-Infrared (MIR) spectroscopies were applied to a set of samples representative of the whole Chianti Classico production area. The non-selective signals (fingerprints) provided by the three spectroscopic techniques were utilised both individually and jointly, after fusion of the respective profile vectors, in order to build a model for the Chianti Classico PDO olive oil. Moreover, these results were compared with those obtained by the gas chromatographic determination of the fatty acids composition. In order to characterise the olive oils produced in the Chianti Classico PDO area, UNEQ (unequal class models) and SIMCA (soft independent modelling of class analogy) were employed both on the MIR, NIR and UV-vis spectra, individually and jointly, and on the fatty acid composition. Finally, PLS (partial least square) regression was applied on the UV-vis, NIR and MIR spectra, in order to predict the content of oleic and linoleic acids in the extra virgin olive oils. UNEQ, SIMCA and PLS were performed after selection of the relevant predictors, in order to increase the efficiency of both classification and regression models. The non-selective information obtained from UV-vis, NIR and MIR spectroscopy allowed to build reliable models for checking the authenticity of the Italian PDO extra virgin olive oil Chianti Classico. Copyright © 2011 Elsevier B.V. All rights reserved.

SOLID-STATE STORAGE DEVICE FLASH TRANSLATION LAYER

DEFF Research Database (Denmark)

2017-01-01

Embodiments of the present invention include a method for storing a data page d on a solid-state storage device, wherein the solid-state storage device is configured to maintain a mapping table in a Log-Structure Merge (LSM) tree having a C0 component which is a random access memory (RAM) device...

X-ray structure determination, Hirshfeld surface analysis, spectroscopic (FT-IR, NMR, UV-Vis, fluorescence), non-linear optical properties, Fukui function and chemical activity of 4‧-(2,4-dimethoxyphenyl)-2,2‧:6‧,2″-terpyridine

Science.gov (United States)

Demircioğlu, Zeynep; Yeşil, Ahmet Emin; Altun, Mehmet; Bal-Demirci, Tülay; Özdemir, Namık

2018-06-01

The compound 4‧-(2,4-dimethoxyphenyl)-2,2‧:6‧,2″-terpyridine (Mtpyr) was synthesized and investigated using X-ray single crystal structure determination, combined with Hirshfeld topology analysis of the molecular packing. In addition, Mtpyr was characterized by experimental and theoretical FT-IR, UV-Vis, 1H NMR, 13C NMR and fluorescence emission spectra. The optimized molecular geometry (bond length, bond angle, torsion angle), the complete vibrational frequency and all other theoretical computations were calculated by using density functional theory (DFT) B3LYP method with the help of 6-311++G(d,p) basis set. From the recorded UV-Vis spectrum, the electronic properties such as excitation energies, wavelength and oscillator strength are evaluated by TD-DFT in chloroform solution. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by the gauge-independent atomic orbital (GIAO) method and compared with experimental results. The calculated HOMO-LUMO band gap energies confirmed that charge transfer and chemical stability within the molecule. The hyperconjugative interaction energy E(2) and electron densities of donor (i) and acceptor (j) bonds were calculated using natural bond orbital (NBO) analysis. Besides Mulliken and natural population charges (NPA), non-linear optic properties (NLO), Fukui Function analysis, molecular electrostatic potential (MEP) were also computed which helps to identifying the electrophilic/nucleophilic nature.

Supercritical Fluid Extraction of Lovastatin from the Wheat Bran Obtained after Solid-State Fermentation

Directory of Open Access Journals (Sweden)

Ruchir C. Pansuriya

2009-01-01

Full Text Available The objective of the present work is to extract lovastatin with minimum impurity by using supercritical carbon dioxide (SC-CO2. A strain of Aspergillus terreus UV 1617 was used to produce lovastatin by solid-state fermentation (SSF on wheat bran as a solid substrate. Extraction of lovastatin and its hydroxy acid form was initially carried out using organic solvents. Among the different screened solvents, acetonitrile was found to be the most efficient. SC-CO2 was used for extraction of lovastatin from the dry fermented matter. The effect of supercritical extraction parameters such as the amount of an in situ pretreatment solvent, temperature, pressure, flow rate and contact time were investigated. The maximum recovery of lovastatin was obtained with 5 mL of methanol as an in situ pretreatment solvent for 1.5 g of solid matrix, flow rate of the supercritical solvent 2 L/min, temperature 50 °C, and contact time 155 min at a pressure 300 bar. The lovastatin extract obtained after optimizing the conditions of supercritical fluid extraction was found to have 5-fold more HPLC purity than the organic solvent extract.

optimisation of solid optimisation of solid state fermentation

African Journals Online (AJOL)

eobe

from banana peels via solid state fermentation using Aspergillus niger. ermentation ... [7,8], apple pomace [9], banana peels [4], date palm. [10], carob ... powder, jams, juice, bar, biscuits, wine etc results in ... Yeast extract was taken as nitrogen.

Solid state synthesis, crystal growth and optical properties of urea and p-chloronitrobenzene solid solution

Energy Technology Data Exchange (ETDEWEB)

Rai, R.N., E-mail: rn_rai@yahoo.co.in [Department of Chemistry, Centre of Advanced Study, Banaras Hindu University, Varanasi 221005 (India); Kant, Shiva; Reddi, R.S.B. [Department of Chemistry, Centre of Advanced Study, Banaras Hindu University, Varanasi 221005 (India); Ganesamoorthy, S. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, Tamilnadu (India); Gupta, P.K. [Laser Materials Development & Devices Division, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India)

2016-01-15

Urea is an attractive material for frequency conversion of high power lasers to UV (for wavelength down to 190 nm), but its usage is hindered due to its hygroscopic nature, though there is no alternative organic NLO crystal which could be transparent up to 190 nm. The hygroscopic character of urea has been modified by making the solid solution (UCNB) of urea (U) and p-chloronitrobenzene (CNB). The formation of the solid solution of CNB in U is explained on the basis of phase diagram, powder XRD, FTIR, elemental analysis and single crystal XRD studies. The solubility of U, CNB and UCNB in ethanol solution is evaluated at different temperatures. Transparent single crystals of UCNB are grown from its saturated solution in ethanol. Optical properties e.g., second harmonic generation (SHG), refractive index and the band gap for UCNB crystal were measured and their values were compared with the parent compounds. Besides modification in hygroscopic nature, UCNB has also shown the higher SHG signal and mechanical hardness in comparison to urea crystal. - Highlights: • The hygroscopic character of urea was modified by making the solid solution • Solid solution formation is support by elemental, powder- and single crystal XRD • Crystal of solid solution has higher SHG signal and mechanical stability. • Refractive index and band gap of solid solution crystal have determined.

ENHANCED CHEMICAL CLEANING: EFFECTIVENESS OF THE UV LAMP TO DECOMPOSE OXALATES

Energy Technology Data Exchange (ETDEWEB)

Ketusky, E.; Huff, T.; Sudduth, C.

2010-01-19

Enhanced Chemical Cleaning is a new process scheduled to begin cleaning Savannah River Site High Level Waste Tanks in 2012. It is an improvement over the current chemical cleaning method, in that it minimizes downstream impacts on the High Level Waste System. It is based on a state of the art scale removal process used on the secondary side of nuclear power plants, with modifications to accommodate the unique constraints created by the tanks. Both Enhanced Chemical Cleaning and the scale removal process are founded on dissolving metal oxides/hydroxides using oxalic acid, with subsequent oxalate decomposition via hydroxylation using ozone or peroxide, and UV light as a catalyst. A divergence Enhanced Chemical Cleaning has from nuclear power scale removal is the significantly increased solids concentration during oxalate decomposition. These solids can limit the ability of the UV light to create hydroxyl radicals, either by limiting the ability of the light to penetrate through the solution, or by increasing the fouling rate on the UV light. Both will decrease the overall catalytic effectiveness, thereby decreasing the concentration of formed hydroxyl radicals. The hydroxyl radicals are the driving force behind the oxalate decomposition. To understand the impact of increased solids, testing was performed using a medium pressure UV light inside an ozone supplied Oxalate Decomposition Reactor. Using a dissolved metal sludge simulant with an initial oxalate concentration greater than 12,000 ppm, and an initial pH of about 2.0, the spent acid solution was recirculated through the reactor, while the UV light was allowed to foul. For the first few hours, the oxalate decomposition rate was about 1,300 ppm/hour. After about 3 hours, enough time for the UV lamp to foul, the oxalate decomposition rate decreased to about 500 ppm/hour. The decomposition rate then remained roughly constant for the next 16 hours. Overall, testing showed that the oxalate destruction rate decreased

The near-UV absorber OSSO and its isomers.

Science.gov (United States)

Wu, Zhuang; Wan, Huabin; Xu, Jian; Lu, Bo; Lu, Yan; Eckhardt, André K; Schreiner, Peter R; Xie, Changjian; Guo, Hua; Zeng, Xiaoqing

2018-05-01

Disulfur dioxide, OSSO, has been proposed as the enigmatic "near-UV absorber" in the yellowish atmosphere of Venus. However, the fundamentally important spectroscopic properties and photochemistry of OSSO are scarcely documented. By either condensing gaseous SO or 266 laser photolysis of an S2O2 complex in Ar or N2 at 15 K, syn-OSSO, anti-OSSO, and cyclic OS([double bond, length as m-dash]O)S were identified by IR and UV/Vis spectroscopy for the first time. The observed absorptions (λmax) for OSSO at 517 and 390 nm coincide with the near-UV absorption (320-400 nm) found in the Venus clouds by photometric measurements with the Pioneer Venus orbiter. Subsequent UV light irradiation (365 nm) depletes syn-OSSO and anti-OSSO and yields a fourth isomer, syn-OSOS, with concomitant dissociation into SO2 and elemental sulfur.

Novel and versatile solid-state chemiluminescence sensor based on TiO2-Ru(bpy)32+ nanoparticles for pharmaceutical drugs detection

Science.gov (United States)

Al-Hetlani, Entesar; Amin, Mohamed O.; Madkour, Metwally

2018-02-01

This work describes a novel and versatile solid-state chemiluminescence sensor for analyte detection using TiO2-Ru(bpy)32+-Ce(IV). Herein, we report the synthesis, characterization, optimization and application of a new type of hybrid nanoparticles (NPs). Mesoporous TiO2-Ru(bpy)32+ NPs were prepared using a modified sol-gel method by incorporating Ru(bpy)32+ into the initial reaction mixture at various concentrations. The resultant bright orange precipitate was characterized via transmission electron microscopy, N2 sorpometry, inductively coupled plasma-optical emission spectrometer (ICP-OES), Raman and UV-Vis spectroscopy techniques. The concentration of Ru(bpy)32+ complex in the NPs was quantified using ICP-OES, and its chemiluminescence (CL) response was measured and compared with the same concentration in the liquid phase using oxalate as model analyte. The results showed that this type of hybrid material exhibited a higher CL signal compared with the liquid phase due to the enlarged surface area of the hybrid NPs ( 149.6 m2/g). The amount of TiO2-Ru(bpy)32+ NPs and the effect of the analyte flow rate were also investigated to optimize the CL signal. The optimized system was further used to detect oxalate and two pharmaceutical drugs, namely, imipramine and promazine. The linear range for both drugs was 1-100 pm with limits of detection (LOD) of 0.1 and 0.5 pm, respectively. This approach is considered to be simple, low cost and facile and can be applied to a wide range of analytes.