Synthesis of polystyrene beads loaded with dual luminophors for self-referenced oxygen sensing

Dispersion polymerization has been successfully applied to synthesize monodisperse polystyrene beads loaded with SiOEP and PtOEP for self-referenced oxygen sensing. The polystyrene beads became larger in size as the concentration of initiator was increased due to the reduction of primary particles precipitated from the polymerization medium. The dual luminophors showed similar absorption spectra but two distinctive emission spectra with peaks at 580 and 650 nm for SiOEP and PtOEP, respectively. While the emission of SiOEP exhibited no response to oxygen, the luminescence intensity of PtOEP was monotonically dependent on the concentration of oxygen. From the Stern-Volmer plot, we observed a linear correlation between the intensity ratio of SiOEP at 580 nm to PtOEP at 650 nm and the concentration of oxygen, which could be used to reliably monitor the partial pressure of oxygen in a system.     

Vibrational spectra of p-chlorobenzaldehyde and its deuterated derivatives

The vibrational modes of parachlorobenzaldehyde are assigned using infrared and Raman spectra, valence force field calculations of normal coordinates, and deuteration effects. Low temperature and isotopic studies show that the band at 310 cm^?1 previously observed as a single band is a closely spaced doublet. One component is assigned as the out-of-plane CCl wagging mode, the other as a mixed CClCHO in-plane bending deformation. A feature of the spectra in all the isotopic parachlorobenzaldehydes is an intense doublet in the 1700 cm^?1 region interpreted as Fermi resonance between a combination band and the carbonyl stretching mode.     

Microwave-assisted synthesis of rhodamine derivatives

The microwave synthesis of 12 rhodamine-derived imines is described. The present work involves condensation of rhodamine hydrazide with various aromatic aldehydes in ethanol under microwave irradiation. The results obtained indicate that, unlike classical heating, microwave irradiation results in higher yields, shorter reaction time, mild reaction condition and simple work-up procedure. The structures of synthesized compounds were confirmed by ¹H-NMR, ¹³C-NMR, FT-IR and high-resolution mass spectra data.     

Daphne mucronata-mediated phytosynthesis of silver nanoparticles and their novel biological applications,compatibility and toxicity studies

This contribution reports the biosynthesis of silver nanoparticles (AgNPs) using aqueous leaf extracts of D. mucronata and their diverse applications. Synthesized AgNPs were characterized using diverse techniques, i.e. UV, XRD, EDS, SEM, TEM, FTIR and TGA/DTA. These techniques confirmed the authenticity of the synthesized nanoparticles. The bimodulated AgNPs revealed the highest radical scavenging potential, i.e. 86.4% relative to plant extract at 600?μg/ml. Escherichia coli was found to be the most susceptible strain to AgNPs. Growth of vancomycin-resistant Staphylococcus aureus was also inhibited. Hemolytic activity revealed negligible hemolysis, indicating the biocompatible nature of biomodulated AgNPs. Furthermore, no mutagenic properties were shown by the biogenic AgNPs. Synthesized nanoparticles possessed promising insecticidal potential and had no phytotoxic activity. No haemagglutination was observed for biogenic AgNPs.     

Antioxidant and prooxidant activity of spent coffee extracts by isothermal calorimetry

Journal of Thermal Analysis and Calorimetry - This work aims to determine the antioxidant and prooxidant activity of spent coffee extracts obtained with (1) a low-pressure (LP) extraction with...     

Protection Group Effects During α,γ‐Diol Lignin Stabilization Promote High‐Selectivity Monomer Production

Protection groups were introduced during biomass pretreatment to stabilize lignin's α,γ‐diol group during its extraction and prevent its condensation. Acetaldehyde and propionaldehyde stabilized the α,γ‐diol without any aromatic ring alkylation, which significantly increased final product selectivity. The subsequent hydrogenolysis catalyzed by Pd/C generated lignin monomers at near‐theoretical yields based on Klason lignin (48 % from birch, 20 % from spruce, 70 % from high‐syringyl transgenic poplar), and with high selectivity to a single 4‐n‐propanolsyringol product (80 %) in the case of the poplar. Unlike direct hydrogenation of native wood, hydrogenolysis of protected lignin with Ni/C also led to high selectivity to this single product (78 %), paving the way to high‐selectivity lignin upgrading with base metal catalysts. The use of extracted lignin facilitated valorization of polysaccharides, leading to high yields of all three major biomass polymers to a single major product.     

A Class of Functional Equations on a Locally Compact Group

Let G be a locally compact group not necessarily unimodular.Let µ be a regular and bounded measure on G. We study,in this paper, the following integral equation, E(µ) This equation generalizes the functional equation for sphericalfunctions on a Gel'fand pair. We seek solutions in the spaceof continuous and bounded functions on G. If is a continuousunitary representation of G such that (µ) is of rank one,then tr((µ)(x)) is a solution of E(µ). (Here, trmeans trace). We give some conditions under which all solutionsare of that form. We show that E(µ) has (bounded and)integrable solutions if and only if G admits integrable, irreducibleand continuous unitary representations. We solve completelythe problem when G is compact. This paper contains also a listof results dealing with general aspects of E(µ) and propertiesof its solutions. We treat examples and give some applications.     

Concerted matrix and pseudo Jahn-Teller perturbations in the 3ππ* → S0 phosphorescence of p-chlorobenzaldehyde at 4.2 K

The aldehyde group out-of-plane vibrational activity in ³ππ^* → S₀ phosphorescence of p-chlorobenzaldehyde in p-xylene and acetophenone matrices at 4.2 K was examined. The τ CHO vibration was found to be very sensitive to the matrix, being very strong in acetophenone and absent (or weak) in p-xylene. This observation, along with evidence for non-adiabatic interactions is interpreted as due to concerted matrix and pseudo Jahn-Teller interactions on the emitting state re-enforcing in acetophenone (leaving the molecule torsionally distorted) and opposing in p-xylene (leaving the molecule planar). The aldehyde H-wag mode (unlike τ CHO) is prominent in the phosphorescence, environmentally insensitive, and interpreted as gaining its activity through Herzberg-Teller and intramolecular distortion effects.