Asphaltenes and insoluble fractions of vacuum residues (VRs) of two Indian crude oils (viz. Heera and Jodhpur) of different specific gravity were obtained by precipitation of VRs in n-hexane, n-heptane, and ethyl acetate, and also ' by subsequent reprecipitation of n-heptane and ethyl acetate soluble fractions by n-pentane. The effect of various solvents on average molecular structure of asphal...

With a reprecipitation method, we prepared fluorescent organic nanoparticles of 1,4-di[(E)-2-phenyl-1-propenyl]benzene (PPB) that feature weak emission in solution but exhibit blue-shifted absorption and strong emission as aggregates. Picosecond fluorescent transients of these PPB nanoparticles showed biexponential decay, described with a consecutive kinetic model involving two emissive states....

Ecosystem nutrient cycling is often complex because nutrient dynamics within and between systems are mediated by the interaction of biological and geochemical conditions operating at different temporal and spatial scales. Vegetated patches in semiarid and wetland landscapes have been shown to exemplify some of these patterns and processes. We investigated biological and geochemical factors sugg...

We report the electrochemical characterization and the observation of excimer emission from a series of 9-naphthylanthracene-based dimer- and trimer-bridged high steric hindrance aromatic groups during photoluminescence (PL) measurements in the solid state and in solution electrogenerated chemiluminescence (ECL) measurements. Cyclic voltammetry of 4,4'-bis(9-(1-naphthyl)anthracen-10-yl)biphenyl...

[1] High‐silica materials have been observed on Mars, both from orbit by the CRISM spectrometer and in situ by the Spirit rover at Gusev Crater. These observations potentially imply a wet, geologically active Martian surface. To understand silica formation on Mars, it is useful to study analogous terrestrial silica deposits. We studied silica coatings that occur on the 1974 Kilauea flow in the ...

This study combines the microstructural and petrological analysis of garnet its inclusions in quartzite-hosted garnetite from ultrahigh-pressure Lago di Cignana metaophiolite (Western Alps). We present a comprehensive record metamorphism, compaction, state stress during interaction between oceanic metasediments infiltrating fluids along major open-system fluid pathway. The arrangement into laye...

The arrangement of an ionic fluorophore in the crystalline state was regulated by the presence of various counter-ions and the effect on spectroscopic and self-association properties was studied. To do so, nine salts of berberine (i.e. a fluorescent natural alkaloid) were investigated. Most of them contained organic anions and were prepared using an ion-exchange process. Berberine chloride and ...

In the course of a study of the rOle of protamines in blood coagulation, to be described in the paper immediately following (I), it was observed that a stable emulsion of highly purifiecl cephalin gave a characteristic precipitate on ad/dition of a solution of the protamine salmine. In contrast, neither lecithin nor sphingomyelin produced precipitates under similar conditions. This reaction whi...

Monazite grains from Nepal and Vietnam were compositionally analyzed with an electron microprobe and dated (Th–Pb) with an ion microprobe. Five sources of uncertainty explain age distributions from single samples that appear inconsistent with a single population: (1) Pb loss due to diffusion, (2) dissolution/reprecipitation reactions along a retrograde path, (3) analytical uncertainties, (4) an...