Synthesis of pentacyclic lα,11-(2-oxethano) steroids

Treatment of a 1α,2α-methyleneandrostan analog (4) with hydrobromic acid/acetic acid gives an apparent intramolecular homoconjugate ring-opening, which serves as the key step in the synthesis of a new type of pentacyclic steroid analogs (2).     

Enhanced structure determination of beta-pyrrole and N-substituted porphyrins by desorption chemical ionization mass spectrometry.

The extensive macrocycle—but minimal substituent—fragmentation occurring in the chemical ionization mass spectra of porphyrins when ammonia, rather than hydrogen, is the reagent gas leads to more detailed structure determinations.     

Cationic flocculants carrying hydrophobic functionalities: applications for solid/liquid separation

The flocculation behaviors of three series of polycations with narrow molecular weight distributions carrying hydrophobic substituents on their backbones [poly(N-vinylbenzyl-N,N,N-trimethylammonium chloride), poly(N-vinylbenzyl-N,N-dimethyl-N-butylammonium chloride), and poly(N-vinylbenzylpyridinium chloride)] were investigated in dispersions of monodisperse polystyrene latexes and kaolin. Apparently, the charge density of the polycations decreases with increasing substituent hydrophobicity and increasing molecular weight of the polyelectrolytes. The necessary amount of flocculant for phase separation in dispersions with high substrate surface charge densities increases with increasing hydrophobicity of the polyelectrolyte. Nevertheless, the introduction of hydrophobic functionalities is beneficial, resulting in a substantial broadening of the range between the minimum and maximum amounts of flocculant necessary for efficient flocculation (flocculation window). An increase in ionic strength supports this effect. When the substrate has a low charge density, the hydrophobic interactions play a much more significant role in the flocculation process. Here, the minimum efficient doses remained the same for all three polyelectrolytes investigated, but the width of the flocculation window increased as the polycation hydrophobicity and the molecular weight increased. The necessary amount of flocculant increased with an increase in particle size at constant solid content of the dispersion, as well as with a decreasing number of particles at a constant particle size.     

CHANGES IN CHLOROPHYLL-PROTEIN COMPLEXES ASSOCIATED WITH JUNE YELLOWS OF STRAWBERRY*

Abstract— June yellows (J-y) of strawberry (Fragaria) is an inheritable condition for which no causal pathogen has been demonstrated. Spectroscopic analysis of intact leaf lamina was applied to strawberry leaves with J-y. The spectra were analyzed by fourth derivative technique. Differences were found between asymptomatic and affected leaves with respect to chlorophyll-protein complexes. Affected leaves show spectra consistent with loss of certain chlorophyll-a-proteins (Ca). Distinct types of effects are found. In one type Ca 684 decreases, in another Ca 693 is diminished. Studies of strawberry clone pedigree suggest that Ca 684 losses are observed in clones with Howard 17 parentage, and Ca 693 losses in clones with Aberdeen parentage. One clone with both Howard 17 and Aberdeen parentage had a spectra consistent with diminished Ca 684 and Ca 693. The simplest explanation of the data is that J-y results from several different types of genetic lesions on different Ca. Some viral infection effects on Ca spectra are also described.