A new paradigm for signal processing of Raman spectra using a smoothing free algorithm: Coupling continuous wavelet transform with signal removal method

Noise removal is considered a primary and inevitable step for background correction in experimentally obtained Raman spectra. Employing an appropriate algorithm for a smoothing‐free background correction technique not only increases the speed but also eliminates unwanted errors from the smoothing algorithms. Herein, we show a new smoothing‐free method for background correction, which we developed by merging continuous wavelet transform and signal removal method, which in combination, could be applied to noisy signals without smoothing. We used wavelet transformation for suppressing the side effects of noise and eliminating peaks from the spectrum, thereby providing spectral sections purely related to the background to be used in the background correction process. We applied a range of statistical analyses to test the performance of this algorithm, wherein a low deviation in background correction procedure was observed. Additionally, when we tested this algorithm for experimentally obtained real Raman spectra, it showed good capability to correct background of noisy signals without the requirement of a smoothing process. Copyright © 2013 John Wiley & Sons, Ltd.     

Piperidinium 3‐[(4‐hydroxy‐5,7‐di­methyl‐2‐oxo‐2H‐chromen‐3‐yl)­phenyl­methyl]‐5,7‐di­methyl‐2‐oxo‐2H‐chromen‐4‐olate

In the title salt, C₅H₁₂N⁺·C₂₉H₂₃O₆^?, both benzo­pyran systems are planar. Intermolecular N—H?O hydrogen bonds and a short O—H?O intramolecular hydrogen bond are observed in the structure.     

Prediction of polymer PVT behavior using the group contribution lattice-fluid EOS

A scheme has been developed using the group contribution lattice-fluid equation of state (GCLF-EOS) to predict the pressure-volume-temperature (PVT) behavior of polymers in the amorphous state. The model requires only the structure of the molecule as input information. Prediction results with an average error of 2% have been obtained for a wide variety of polymers. A table of 23 different group contributions is presented. With this set of group parameters, the GCLF-EOS can be applied in the prediction of equation of state properties of a wide variety of homopolymers, random copolymers, and polymer blends. © 1995 John Wiley & Sons, Inc.     

Cellulose-based fibers from liquid crystalline solutions. IV. Effects of lithium chloride on acetate/butyrate esters

Cellulose acetate butyrate (CAB) fibers were prepared by spinning from liquid crystalline (LC) solutions containing lithium chloride (LiCl). Ionic interactions were observed between carbonyl oxygen and lithium cation by ¹³C nuclear magnetic resonance (NMR) spectroscopy. Isotropization of the anisotropic phase by LiCl was found to cause a dramatic rise in the viscosity of LC solutions. The mechanosorptive creep behavior described earlier decreased in the presence of residual LiCl salt, possibly due to the formation of electrostatic interactions between Li⁺ and CAB backbone. © 1994 John Wiley & Sons, Inc.     

Design, synthesis and utilization of a novel coupling reagent for the preparation of O-alkyl hydroxamic acids

An efficient novel reagent, phosphoric acid diethyl ester 2-phenyl-benzimidazol-1-yl ester, was designed, and synthesized and its applicability was demonstrated for the preparation of O-alkyl hydroxamic acids. The O-alkyl hydroxamic acids of N-protected amino acids were also synthesized. The enantiomeric purity of the synthesized compounds were measured using chiral HPLC and the degree of racemization was found to be negligible.     

Galvanic replacement mediated synthesis of hollow Pt nanocatalysts: Significance of residual Ag for the H2 evolution reaction

With the increasing popularity of the galvanic replacement approach towards the development of bimetallic nanocatalysts, special emphasis has been focused on minimizing the use of expensive metal (e.g. Pt), in the finally formed nanomaterials (e.g. Ag/Pt system as a possible catalyst for fuel cells). However, the complete removal of the less active sacrificial template is generally not achieved during galvanic replacement, and its residual presence may significantly impact on the electrocatalytic properties of the final material. Here, we investigate the hydrogen evolution reaction (HER) activity of Ag nanocubes replaced with different amounts of Pt, and demonstrate how the bimetallic composition significantly affects the activity of the alloyed nanomaterial.     

Pattern profiling of the herbal preparation picroliv using liquid chromatography-tandem mass spectrometry

At present, the construction of chromatographic fingerprints of complex herbal preparations in combination with mass spectrometry plays an important role in their development and standardization as potential therapeutic agents. Picroliv, an extract from roots and rhizomes of Picrorhiza kurroa, is a herbal hepatoprotective developed by CDRI. We report for the first time pattern profiling of various constituents of picroliv along with a precise and accurate method to estimate relative concentration of major components in the preparation by liquid chromatography-tandem mass spectrometry. In total, 27 components could be detected in multiple reaction monitoring (MRM) mode out of which fourteen could be quantified in terms of their relative concentration. Seven components were structurally correlated and confirmed based on the fragmentation pattern and information available in literature. The detection was carried out using MRM in negative ionization mode with analytes quantified from the summed total ion value of their most intense molecular ion transitions. The separation of various components was achieved using a gradient elution on RP-18 column with acetonitrile and Milli-Q water as mobile phase at a flow rate of 1.0 ml/min. The method was validated in terms of linearity, accuracy and precision (within- and between-assay variation) for 5 days. Linearity range was different for various components depending upon their sensitivity and abundance in the herbal preparation. Within- and between-assay accuracy (%bias) and precision (%R.S.D.) were within acceptable limits. The method was successfully applied to detect and determine relative concentrations of various components in two different batches of picroliv.     

Minimal Simplicial Self-maps of the 2-Sphere

For any d (resp. for almost all d) we compute the least number (d) of vertices which a triangulation K of the 2-sphere (resp. any other orientable surface) must have in order that there exists a degree d simplicial map from K to the 4-vertex 2-sphere. We also prove an analogous result for uniquely 4-colourable Ks.