Thioreduction of cyclopentanone and hydrodesulfurization of dibenzothiophene over sulfided nickel or cobalt-promoted molybdenum on alumina catalysts

Two series of sulfided Ni or Co promoted Mo/alumina catalysts, having different Ni or Co loadings, were characterized by their activities for the transformation of cyclopentanone into cyclopentanethiol (flow reactor, 220°C, atmospheric pressure) and for the hydrodesulfurization of dibenzothiophene (flow reactor, 340°C, 3 MPa hydrogen pressure). The addition of the promoter increased significantly the activity of the Mo/alumina catalyst for both reactions, up to a maximum obtained with the catalysts having a (promoter)/(promoter+Mo) molar ratio equal to 0.3–0.4. This increase in activity was due in part to an increase in the hydrogenating properties of the Mo/alumina catalyst. However, an additional modification of the catalyst (basic and nucleophilic properties) must be considered to account for the spectacular effect of the promoter on the rate of the dibenzothiophene direct desulfurization reaction.     

2-Methyl-3-oxo-4-phenyl-2,3-dihydrofuran-2-yl acetate: a fluorogenic reagent for detection and analysis of primary amines

A new fluorogenic reagent, 2-methyl-3-oxo-4-phenyl-2,3-dihydrofuran-2-yl acetate, has been developed for the analysis of primary amines and aminated carbohydrates by means of HPLC, CE, and MALDI/MS. Peptides at 1 pmol (2 x 10(-7) M) levels were successfully labeled and analyzed through CE. The fluorescent derivatives have good stability in both acidic and basic solutions, making their further manipulation and structural analysis possible. The derivatives can be analyzed in reversed-phase HPLC due to the hydrophobic nature of this fluorescent tag. Characteristic elution intervals between the diastereomeric peaks of the chiral peptide derivatives may be used in structural verification. The labeled peptides and neutral oligosaccharides are also readily detectable through MALDI/MS in its positive mode.     

Synthesis,structure and catalytic activities for hydrogen transfer reaction of the carbonyl ruthenium(II) complex containing polypyridine and phosphine ligands

The synthesis and characterization of new ruthenium(II) carbonyl complexes containing polypyridine and triphenylphosphine ligands is reported. Crystallographic information obtained for the trans-PPh₃-[Ru(biq)(PPh₃)₂(CO)]Cl₂ complex (biq = 2,2’-biquinoline) reveals five-coordination on the metal. The complexes were studied as catalysts in hydrogen transfer reactions in basic solution. Turnover frequencies in the 2250-817 h^-1 range were determined in 1 hour of reaction with a substrate/catalysts ratio of 830.     

Effects of feeding whole cottonseed on composition of milk

Complete mixed diets containing 0, 10, 15, or 20% whole cottonseed were fed to 12 cows in a 4 X 4 Latin square design. Cows were assigned to the Latin square by production status resulting in one square each for cows in early first lactation and older cows either in early or late lactation. Diets were fed for ad libitum intake, and periods were 21 days. Percentages of milk fat and total solids increased, and protein percentage decreased with cottonseed feeding. Milk casein nitrogen decreased from .387 to .375% with cottonseed feeding. Nitrogen in whey remained unchanged, and nonprotein nitrogen increased. Proportion of total nitrogen in casein and whey fractions was not altered, but proportion of nonprotein nitrogen increased. Cottonseed decreased proportions of short-chain fatty acids (carbon-6 to carbon-16) in milk and increased stearic and oleic acids. Actual yield of milk was not affected by cottonseed feeding, but yields of fat-corrected milk and milk fat were increased. Production status affected milk composition with older cows in early lactation producing milk of lower fat, total solids, and protein content compared with cows in other groups. Casein nitrogen was highest for first-lactation and lowest for older, high-producing cows. Whey nitrogen was highest for older, low-producing cows. First-lactation cows had the highest proportion of nitrogen in the casein fraction, and older, low-producing cows had the lowest. Milk fatty acid composition changed little with status.     

Synthesis,structure and electrochemical properties of the cationic complex tris-(imidazolidine-1,10-phenanthroline)iron(II)

The complex [Fe^II(Imz-phen)₃](PF₆)₂, (Imz-phen = imidazolidine-[4,5-f]-1,10-phenanthroline) has been prepared and characterized using X-ray diffraction, UV–vis and IR spectroscopy, elemental analysis, fast atomic bombardment (FAB) mass spectrometry, and cyclic voltammetry. Its crystal lattice includes acetonitrile (π–π bound to phenanthroline), methanol, and water molecules. Scanning continuously between 1000 mV and 1650 mV in CH₃CN, a modified electrode that includes the iron (II) complex is obtained; after the 25th continuous cycle a stable film is formed that is electrocatalytically active in the reduction of sulfur oxoanions. When the electrocatalytic properties are evaluated in ethanol/water solution, the current achieved from the electroreduction of these sulfur species is linearly dependent on the respective concentrations, suggesting potential application in sulfite determination.     

Compacity influence in reorganization of two dimensional granular packings: Numerical model

Rearrangements (movements of disks) of different sizes are observed before the avalanche onset while studying avalanche process in 2D packings of disks of diameter d. A stochastic cellular automata model based on experimental observations is proposed to understand the influence of local packing fraction in the appearance of rearrangements in a two dimensional packing of disks. In numerical simulations, rearrangements of different sizes are also observed and evolution of the packing fraction is studied. The cellular automata retrieves experimental results when it considers a range of influence for rearrangements larger than 9d. Rearrangements are also found to be responsible for the decreasing of the system global packing fraction in discrete steps.