Complexes of AgI with cationic ligands: bis[(pyridylmethyl)ammonio]silver(I) salts

Bis­[(2-pyridyl­methyl)­ammonio]silver(I) trinitrate, [Ag(C₆H₉N₂)₂](NO₃)₃, (I), and bis{bis­[(4-pyridyl­methyl)­ammonio]silver(I)} hexakis­(perchlorate) dihydrate, [Ag(C₆H₉N₂)₂]₂(ClO₄)₆·2H₂O, (II), are rare examples of complexes with cationic ligands. In (I), the Ag⁺ cation has a T-shaped [2+1] coordination involving the pyridine N atoms and a nitrate O atom, while in (II) there are three independent two-coordinate Ag complex cations (two with the Ag atoms on independent inversion centres) and disordered ClO₄⁻ ions. The crystal structures reveal the role of hydrogen bonding in stabilizing these complexes.     

Absolute spectral distribution of soft X-ray emission from laserproduced gold plasma

Quantitative measurement of spectral distribution of soft X-ray emission from laser produced plasmas and estimation of X-ray conversion efficiency are reported. The X-ray emission from planar gold target irradiated by an Nd:glass laser was recorded using a high resolution transmission grating spectrograph. Spectral distribution of X-ray intensity was derived using calibrated film data and a deconvolution procedure to account for contribution of higher diffraction orders. Results of conversion efficiency per unit solid angle, at a laser intensity of ~4×10¹² W/cm² (λ_L = 1.054 μm), for 10< λ <80 Å and in the water window spectral region (23< λ< 44 Å) are presented. A three-fold increase in conversion efficiency was observed for second harmonic laser irradiation (λ_L = 0.527 μm) at an intensity of 8×10¹² W/cm²     

Three simple spectrophotometric methods for the determination of sulphinpyrazone

Three simple and sensitive spectrophotometric methods for the determination of sulphinpyrazone (SP) in bulk samples and pharmaceutical formulations are described. They are based on the oxidation of sulphinpyrazone with excess N-bromosuccinimide (NBS) and determination of the unconsumed NBS with metol-isonicotinic acid hydrazide (method A, lambda(max): 620 nm); by the reduction of Folin-Ciocalteu reagent (method B, lambda(max) 770 nm); or by the formation of a chloroform-soluble, coloured ion-association complex between the drug and Methylene Violet (MV) at pH 7.0 (method C, lambda(max) 545 nm).     

Evaluation of thermal and flame properties of HDPE-MWCNT-SiO2 nanocomposites

High-density polyethylene (HDPE) composites reinforced with multiwalled carbon nanotubes (MWCNTs) and nano-silicon dioxide (SiO₂) fillers were evaluated for flame retardancy and thermal properties for cable and wire applications. In this study, the filler percentages of MWCNT and nano-SiO₂ have varied from 0 to 5 wt% in HDPE composite with polyethylene-grafted glycidyl methacrylate compatibilizer and 3-aminopropyl triethoxy silane coupling agent. Addition of MWCNT’s and nano-SiO₂ to the HDPE composite is observed to enhance the limiting oxygen index and char formation. Cone calorimeter results also show a 53% reduction in the peak heat release rate of the HDPE composite with 5 wt% of MWCNT. The existence of synergism between the uniformly dispersed MWCNT and nano-SiO₂ has been verified using Finite Element Method (FEM)-based thermal simulations.     

Emission spectrum of PrO

The bands of PrO at 8488.95 A and 7986.44 A of system I and at 7662.85 A of system III have been photographed on 6.6 meter concave grating spectrograph at a dispersion of 1.2 A/mm and their rotational structure analysed. They are assigned transitions fromv′ = 0 and 1 levels of A² Δ_5/2 andv′ = 0 level of B² Δ_5/2 to a commonv′’ = 0 level of the ground, X² Π_3/2 state.     

Optical characterization of Eu3+ and Tb3+ ions doped cadmium lithium alumino fluoro boro tellurite glasses

This article reports on the development and spectral results of Eu(3+) and Tb(3+) ions doped cadmium lithium alumino fluoro boro tellurite (CLiAFBT) glasses in the following composition. 40TeO2-30B2O3-10CdO-10Li2O-10AlF3 (Hostglass) (40-x)TeO2-30B2O3-10CdO-10Li2O-10AlF3-xEu2O3 (40-x)TeO2-30B2O3-10CdO-10Li2O-10AlF3-xTb4O7 where x=0.25, 0.50, 0.75, 1.0, 1.25 mol%. Glass amorphous nature and thermal properties have been studied using the XRD and DSC profiles. From the emission spectra of Eu(3+):glasses, five emission transitions have been observed at 578 nm, 592 nm, 612 nm, 653 nm, 701 nm and are assigned to the transitions (5)D(0)→(7)F(0), (7)F(1,)(7)F(2), (7)F(3) and (7)F(4), respectively, with λ(exci)=392 nm ((7)F(0)→(5)L(6)). In case of Tb(3+):glasses, four emission transitions ((5)D(4)→(7)F(6,)(7)F(5), (7)F(4) and (7)F(3)) are observed at 488 nm, 543 nm, 584 nm and 614 nm, respectively, with λ(exci)=376 nm. Decay curves and energy level diagrams have been plotted to evaluate the life times and to analyze the emission mechanism.     

Raman labeled nanoparticles: characterization of variability and improved method for unmixing

Raman spectroscopy can differentiate the spectral fingerprints of many molecules, resulting in potentially high multiplexing capabilities of Raman‐tagged nanoparticles. However, an accurate quantitative unmixing of Raman spectra is challenging because of potential overlaps between Raman peaks from each molecule, as well as slight variations in the location, height, and width of very narrow peaks. If not accounted for properly, even minor fluctuations in the spectra may produce significant error that will ultimately result in poor unmixing accuracy. The objective of our study was to develop and validate a mathematical model of the Raman spectra of nanoparticles to unmix the contributions from each nanoparticle allowing simultaneous quantitation of several nanoparticle concentrations during sample characterization. We developed and evaluated an algorithm for quantitative unmixing of the spectra called narrow peak spectral algorithm (NPSA). Using NPSA, we were able to successfully unmix Raman spectra of up to seven Raman nanoparticles after correcting for spectral variations of 30% intensity and shifts in peak locations of up to 10 cm⁻¹, which is equivalent to 50% of the full width at half maximum (FWHM). We compared the performance of NPSA to the conventional least squares (LS) analysis. Error in the NPSA is approximately 50% lower than in the LS. The error in estimating the relative contributions of each nanoparticle with the use of the NPSA are in the range of 10–16% for equal ratios and 13–19% for unequal ratios for the unmixing of seven composite organic–inorganic nanoparticles (COINs); whereas, the errors from using the traditional LS approach were in the range of 25–38% for equal ratios and 45–68% for unequal ratios. Here, we report for the first time the quantitative unmixing of seven nanoparticles with a maximum root mean square of the percentage error (RMS%) error of less than 20%. Copyright © 2012 John Wiley & Sons, Ltd.