Nile Red Synchronous Scan Fluorescence Spectroscopy to Follow Matrix Modification in Sol–Gel Derived Media and its Effect on the Peroxidase Activity of cytochrome <Emphasis Type="Italic">c</Emphasis>

The highly solvatochromic dye Nile red is used in conjunction with synchronous scan fluorescence spectroscopy to elucidate changes in the internal environment of cytochrome c, upon incorporation into differently modified sol–gel derived media. Nile red was first studied in a variety of solvents in order to quantify changes in polarity. Matrix modifications involved the addition of several silanes, intended to interact with any unreacted hydroxyl entities left from the matrix forming reaction, while polymers were used to help reduce shrinkage and modify the internal pore environment. Slight unfolding of the protein was observed on incorporation into the sol–gel derived media. During the aging process further changes were monitored by using difference synchronous scan fluorescence spectra and complementary measurements of catalytic activity, expressed as the initial velocity. Combining Nile red synchronous scan fluorescence with cytochrome c activity data lead to a method to elucidate effects linked to protein conformation and those related to the sol–gel derived host. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Luminescence of Nile red as indicator of composition of nanoparticles from diketonate complexes of trivalent metals

We study the sensitization of fluorescence of Nile red in nanoparticles formed in aqueous solutions of complexes of Al, In, Sc, and Lu with DBM, DBM, and phen and of complexes of In with MBTA and phen. We show that, at concentrations of Nile red of 2–50 nM and complexes of 10–30 μM, the fluorescence intensity of Nile red in aqueous solutions increases by 1.5–2 orders of magnitude compared to its fluorescence in H₂O. We find that, at these concentrations of Nile red in solutions of complexes Al, the dye is completely contained in nanoparticles from these complexes. We show that Nile red molecules are inhomogeneously distributed in nanoparticles from complexes and, upon the completion of the formation of nanoparticles, dye molecules tend to be localized in regions of nanoparticles formed from diketonate complexes M(diketone)₃phen (M is Lu or In) and Al(DBM)₃. Upon the localization of Nile red in these regions, the maximum of its fluorescence spectrum shifts toward ∼600 nm and, upon the penetration of Nile red into nanoparticles from Sc complexes, the shift of the maximum of its fluorescence spectrum compared to the spectrum in water does not exceed 10 nm. The shifts of the spectra are collated with the ability of ions to form diketonate and hydroxy diketonate complexes. We demonstrate that the fluorescence of Nile red is efficiently sensitized, not only upon its penetration into nanoparticles formed from complexes, but also upon its adsorption on the nanoparticle surface when Nile red molecules are introduced in solutions of already formed nanoparticles.     

Nucleobase-Specific Enhancement of Cy3 Fluorescence

We report on the role of dye–nucleobase interactions on the photophysical properties of the indocarbocyanine Cy3. The fluorescence efficiency and lifetime of Cy3 increase in the presence of all four nucleoside monophosphates. This behavior correlates with an increase in the activation energy for photoisomerization and a ∼4 nm red shift in the fluorescence spectrum. Changes are more dramatic for the purines (dAMP, dGMP) than the pyrimidines (dCMP, dTMP), and for the nonsulfonated cyanine (DiIC₂(3)) than the sulfonated dye (Cy3–SE). These results are consistent with a model in which Cy3–nucleoside π–π interactions decrease the efficiency of photoisomerization, increasing the efficiency of fluorescence. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Sensitive Spectroscopic Detection of Large and Denatured Protein Aggregates in Solution by Use of the Fluorescent Dye Nile Red

The fluorescent dye Nile red was used as a probe for the sensitive detection of large, denatured aggregates of the model protein β-galactosidase (E. coli) in solution. Aggregates were formed by irreversible heat denaturation of β-galactosidase below and above the protein’s unfolding temperature of 57.4°C, and the presence of aggregates in heated solutions was confirmed by static light scattering. Interaction of Nile red with β-galactosidase aggregates led to a shift of the emission maximum (λ _max) from 660 to 611 nm, and to an increase of fluorescence intensity. Time-resolved fluorescence and fluorescence correlation spectroscopy (FCS) measurements showed that Nile red detected large aggregates with hydrodynamic radii around 130 nm. By steady-state fluorescence measurements, it was possible to detect 1 nM of denatured and aggregated β-galactosidase in solution. The comparison with size exclusion chromatography (SEC) showed that native β-galactosidase and small aggregates thereof had no substantial effect on the fluorescence of Nile red. Large aggregates were not detected by SEC, because they were excluded from the column. The results with β-galactosidase demonstrate the potential of Nile red for developing complementary analytical methods that overcome the size limitations of SEC, and can detect the formation of large protein aggregates at early stages.     

Paramagnetic properties of ion-implanted polymer layers

Films of polyethylene, polyethylene terephthalate, and polyamine-6 implanted with B⁺ and N⁺ ions with an energy of 100 keV are investigated by an EPR method in a dose interval of 1·10¹⁴–1·10¹⁷ cm⁻². It is shown that paramagnetic centers with g=2.0025 formed in the implanted polymers have a nature similar to the nature of paramagnetic centers of pyrolized and initially conducting polymers. Correspondence of the character of the variation in paramagnetic characteristics of the modified polymers to the model proposed earlier for the formation of pyrocarbon “drops” in ion implantation is revealed. The relaxation times for paramagnetic centers in the implanted polymer films are calculated and assumptions are made about the formation of a quasi-two-dimensional electron gas as well as the possibility of magnetic ordering in polymer-film layers modified by high-dosage implantation. The effect of oxygen on the electron states of the implanted polymer specimens is studied. Belarusian State University, 4, Skorina Ave., Minsk, 220050 Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 4, pp. 562–567, July–August, 1998.     

Estimation of the binding ability of main transport proteins of blood plasma with liver cirrhosis by the fluorescent probe method

We present results from an investigation of the binding ability of the main transport proteins (albumin, lipoproteins, and α-1-acid glycoprotein) of blood plasma from patients at different stages of liver cirrhosis by the fluorescent probe method. We used the hydrophobic fluorescent probes anionic 8-anilinonaphthalene-1-sulfonate, which interacts in blood plasma mainly with albumin; cationic Quinaldine red, which interacts with α-1-acid glycoprotein; and neutral Nile red, which redistributes between lipoproteins and albumin in whole blood plasma. We show that the binding ability of albumin and α-1-acid glycoprotein to negatively charged and positively charged hydrophobic metabolites, respectively, increases in the compensation stage of liver cirrhosis. As the pathology process deepens and transitions into the decompensation stage, the transport abilities of albumin and α-1-acid glycoprotein decrease whereas the binding ability of lipoproteins remains high. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 4, pp. 507–511, July–August, 2007.     

Controlled synthesis of gold nanospheres and single crystals in hydrogel

Narrow-dispersed gold nanospheres, regular single-crystal nanoplates and nanobulks were prepared, respectively, by reducing HAuCl₄ within a hydrogel system under UV irradiation. The formation of gold products with different geometric shape and size was found to depend on both the microenvironment of the gel matrix and the initial concentration of HAuCl₄. The resultant gold particles were investigated by UV–vis spectroscopy, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and energy-dispersion X-ray spectroscopy. Electronic Supplementary Material The online version of this article at (doi: ) contains supplementary material, which is available to authorised users.     

Generalized Orthogonal Polynomials, Discrete KP and Riemann–Hilbert Problems

Classically, a single weight on an interval of the real line leads to moments, orthogonal polynomials and tridiagonal matrices. Appropriately deforming this weight with times t= (t ₁, t ₂, …), leads to the standard Toda lattice and τ-functions, expressed as hermitian matrix integrals. This paper is concerned with a sequence of t-perturbed weights, rather than one single weight. This sequence leads to moments, polynomials and a (fuller) matrix evolving according to the discrete KP-hierarchy. The associated τ-functions have integral, as well as vertex operator representations. Among the examples considered, we mention: nested Calogero–Moser systems, concatenated solitons and m-periodic sequences of weights. The latter lead to 2m+ 1-band matrices and generalized orthogonal polynomials, also arising in the context of a Riemann–Hilbert problem. We show the Riemann–Hilbert factorization is tantamount to the factorization of the moment matrix into the product of a lower–times upper–triangular matrix. Received: 8 September 1998 / Accepted: 27 April 1999     

Primary solid state batteries

Low - cost, easily fabricated dry cells were constructed by gluing a composite conducting material or a metal sulphide on magnesium or aluminium foils, using a solid electrolyte made from polyvinyl - pyrolidone. Composite conducting materials consisted of polypyrrole and polyaniline incorporated into an inorganic or polymer matrix or cupric oxide incorporated into a styrene - butadiene copolymer matrix. The efficiency, energy densities and voltage values of the cells were in the range 0.5 – 18.3 mWh cm⁻³, 9 – 339 wh kg⁻¹ and 0.5 – 2.0 V, respectively. The energy densities of the cells were up to seventeen times more than the energy density of the PbO₂ -H₂SO₄ - Pb multiple charge / discharge system and up to ten times more than the energy density of the nickel / cadmium rechargeable cell. A dry cell composed solely from polymers was constructed with cell voltage 0.25 – 0.50 V and efficiency ranging from 0.07 to 0.13 mWh cm⁻³ ten times lower than other commercial cells. Paper presented at the 1st Euroconference on Solid State Ionics, Zakynthos, Greece, 11–18 Sept. 1994     

Organic fiber reinforced plastics based on complex hybrid matrices including polysulfone and carbon nanotubes as modifiers of epoxy resins

Organic Fiber Reinforced Plastics (OFRP) based on aramid fibers are as a rule used in constructions working under extremal conditions. In view of this, the possibility of increasing the resistance of OFRP to destruction by modifying matrices with thermoplastic polymers and carbon nanotubes (CNTs) offers much promise. In this work, we present the results obtained in a study of the properties of OFRP based on Rusar fibers and epoxy matrices containing either CNTs or a thermoplastic (PSK-1 polysulfone) or both these components simultaneously. The data obtained substantiate the possibility of using epoxypolysulfone matrices for the preparation of wound composites. This modification noticeably increases crack and impact resistance of OFRP based on aramid fibers without decreasing the glass transition temperature, as when matrices are plasticized by rubber and active diluents. The strongest effect of polysulfone introduced into an epoxy matrix is observed at a large (20 wt %) content of PSK-1. The modification of epoxypolysulfone matrices by CNTs also increases the shear strength of OFRP and almost does not change the fracture toughness and compression strength. The introduction of CNTs into epoxy matrices is less effective and can increase crack growth resistance of OFRP by approximately 30% only at a large (1%) content of CNTs. Small CNT admixtures (0.3–0.6%) do not influence the fracture toughness. Possible mechanisms of the changes observed are considered.     

Tunable Fano resonances in silver–silica–silver multilayer nanoshells

We study the plasmonic properties of silver–silica–silver multilayer nanoshells using finite-difference time-domain methods. Silver is a weakly dissipating metal and is able to support higher order resonances compared to strongly dissipating metals like gold. We show that Fano resonances occur even in symmetric cases. Symmetry breaking via the introduction of core offset further enhances these Fano resonance peaks and leads to the appearance of higher order resonances. The optical properties of the multilayer nanoshells are explained using the plasmon hybridization theory and the results are compared to similar multilayer nanoshells with gold core and outer shell.     

The first spectroscopic analysis of Ethiopian prehistoric rock painting

An extensive micro‐Raman spectroscopic study of prehistoric rock paintings found in Hararghe region, Ethiopia, was carried out, with the aim to evaluate the production skill of the local artist and the period of production of the discovered paintings. Attenuated Total Reflection Fourier Transform Infrared (ATR‐FTIR) Spectroscopy and Laser Induced Breakdown Spectroscopy (LIBS) were used as auxiliary techniques. Micro sampling were carried out on parts of red, white, black painting figures representing domestic and wild animals. The pigments used by artists were hematite for red color, calcite or gypsum for white color, and carbonaceous material for black coloration. A green pigment was also investigated; it resulted made of green earth. A consistent amount of Ca‐oxalate was found particularly on red samples as well as on the white ones. Former studies attributed oxalates origin to a biological substrate attack, whereas in the present case Ca‐oxalate is ascribed to the use of an organic stuff to spread properly the pigments on the substrate.Principal Component Analysis was performed on the hematite spectra; it evinced that the spectral features could be indicative of different sites and of the relative age.1These novel evaluations put into new perspective the knowledge about rock art pictorial technology of the Horn of Africa. Copyright © 2011 John Wiley & Sons, Ltd.     

Calcium in ancient glazes and glasses: a XAFS study

Ceramic tiles used to manufacture artistic panels during the XVI to the XVIII centuries were decorated with high-lead soda-lime glazes, incorporating a diversity of chromophore cations, as ascertained by SRXRF (synchrotron radiation X-ray fluorescence). Previous X-ray absorption spectroscopy (XAS) studies have shown that sodium and lead are hosted by the glassy matrix in those glazes. However, the possible role of calcium as a modifier of the tetrahedral silica network is not fully clarified, despite being recognized that calcium cations alter some fundamental properties of glazes, namely transparency. An X-ray absorption fine structure (XAFS) study of glazes with varied colorings was therefore undertaken at Ca K- and L-edges. Well crystallized oxide minerals were used to model distinct coordination environments by oxygen atoms – close to octahedral geometry in calcite and dodecahedral in gypsum – while fluorite was chosen to mimic ideal cubic coordination. A first XAS approach suggested a minor variation in the energy separation between L₂–L₃ absorption edges when comparing blue and yellow glazes, irrespective of the period of manufacture. A further study on the X-ray absorption near-edge structure (XANES) carried out at the K-edge corroborated this difference and, along with the theoretical spectra modeling performed with the FEFF code, allowed interpreting of the Ca 1s absorption spectra of glazes as arising from a non-regular high-coordination environment within the silica matrix. PACS  61.43.Fs; 41.60.Ap; 61.10.Ht     

Isotope shifts and accurate wavelengths in Ne II and Ne III

Transition isotope shifts of 3s–3p transitions in Ne II and Ne III are measured in Fourier transform spectra from a hollow-cathode source. Accurate absolute line-center positions of the ²⁰Ne isotope are derived for the purpose of tertiary wavelength standards in the region 2000–5000 ?. A robust statistical treatment is applied, yielding line-position uncertainties that are lower than for the Ar II secondary standards used as references. The influence of Stark shifts on both the new Ne II standards and the Ar II standards is also investigated. In addition, improved wavenumbers of the 3p–3d and 3p–4s transitions are presented, of which 12 in Ne II have been measured for the first time. Electronic supplementary material Supplementary Online Material     

Immobilization and Characterization of 2,3-diaminonaphthalene/cyclodextrin Complexes in a Sol–Gel Matrix: A New Fluorimetric Sensor for Nitrite

The aromatic diamino compound 2,3-diaminonaphthalene (DAN) has been extensively used to detect and quantify nitrite ions in biological and environmental samples. We have immobilized the DAN reagent in a porous silicate glass matrix, via previous incorporation of the dye in HP-β-CD. Changes in fluorescence intensity were used to characterize the inclusion complexes and determine the association constant and stoichiometry of the process. Fluorescence spectrum of these complexes was also used to monitor their immobilization within the sol–gel matrix. Reactivity of the immobilized complexes was evaluated with increasing concentrations of nitrite up to 10 μM (with a detection limit around 20 nM). Results show that sol–gel immobilization does not modify the reactivity of the dye against nitrite and serves to prepare a highly sensitive ready to use fluorescence-based sensor for the specific measurement of nitrite at submicromolar concentrations with no further sample pretreatment.     

Fano resonances in stubbed quantum waveguides with impurities

We consider T–shaped, two–dimensional quantum waveguides containing attractive or repulsive impurities with a smooth, realistic shape, and study how the resonance behavior of the total conductance depends upon the strength of the defect potential and the geometry of the device. The resonance parameters are determined locating the relevant S–matrix poles in the Riemann energy surface. The total scattering operator is obtained from the S–matrices of the various constituent segments of the device through the –product composition rule. This allows for a numerically stable evaluation of the scattering matrix and of the resonance parameters.     

On algebraic structures in supersymmetric principal chiral model

Using the Poisson current algebra of the supersymmetric principal chiral model, we develop the algebraic canonical structure of the model by evaluating the fundamental Poisson bracket of the Lax matrices that fits into the r–s matrix formalism of non-ultralocal integrable models. The fundamental Poisson bracket has been used to compute the Poisson bracket algebra of the monodromy matrix that gives the conserved quantities in involution. PACS 11.30.Pb; 02.30.Ik     

Impedance spectroscopy of iron-doped lithium niobate crystals

The dc conductivity of as-grown and oxidized iron-doped lithium niobate crystals is measured by impedance spectroscopy in the temperature range 30–700 °C. Electron and ion conduction at lower and higher temperatures are clearly distinguished, providing relevant information for understanding and optimizing the recently developed thermo-electric oxidization that makes crystals robust against optical damage. Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users. PACS 77.84.Dy; 72.20.Fr     

Three-class classification models of logS and logP derived by using GA–CG–SVM approach

In this investigation, three-class classification models of aqueous solubility (logS) and lipophilicity (logP) have been developed by using a support vector machine (SVM) method combined with a genetic algorithm (GA) for feature selection and a conjugate gradient method (CG) for parameter optimization. A 5-fold cross-validation and an independent test set method were used to evaluate the SVM classification models. For logS, the overall prediction accuracy is 87.1% for training set and 90.0% for test set. For logP, the overall prediction accuracy is 81.0% for training set and 82.0% for test set. In general, for both logS and logP, the prediction accuracies of three-class models are slightly lower by several percent than those of two-class models. A comparison between the performance of GA–CG–SVM models and that of GA–SVM models shows that the SVM parameter optimization has a significant impact on the quality of SVM classification model. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Hui Zhang and Ming-Li Xiang are contributed equally.     

Uniform Fe3O4–PANi/PS composite spheres with conductive and magnetic properties and their hollow spheres

Core–shell multifunctional composite spheres consisting of Fe₃O₄–polyaniline (PANi) shell and polystyrene (PS) core were fabricated using core–shell-structured sulfonated PS spheres (with uniform diameter of 250 nm) as templates. PANi was doped in situ by sulfonic acid resulting the composite spheres are well conductive. Dissolved with solvent, PS cores were removed from the core–shell composite spheres and hollow Fe₃O₄–PANi spheres were obtained. Removing the PANi and PS components by calcinations produced hollow Fe₃O₄ spheres. The cavity size of the hollow spheres was uniformly approximate to 190 nm and the shell thickness was 30 nm. The cavity size and the shell thickness can be synchronously controlled by varying the sulfonation time of the PS templates. The shell thickness in size range was of 20–86 nm when the sulfonation time was changed from 1 to 4 h. These resulting spheres could be arranged in order by self-assembly of the templates. Both the Fe₃O₄–PANi/PS composite spheres and the hollow Fe₃O₄ spheres exhibit a super-paramagnetic behavior. Scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray powder scattering were used to characterize these as-prepared spheres. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.