Enhanced NH<Subscript>3</Subscript>-SCR activity of Sb-V/CeO<Subscript>2</Subscript>–TiO<Subscript>2</Subscript> catalyst at low temperatures by synthesis modification

In this work, the synthesis of Sb-V/CeO₂–TiO₂ catalyst was modified by controlling pH with the addition of monoethanolamine solution. All the catalysts were systematically investigated for NO _x reduction with NH₃ at different reaction conditions and then characterized by XRD, BET-surface area, X-ray photoelectron spectroscopy, NO-TPD, NH₃-TPD, and H₂-TPR. This modified synthesis method for the Sb-V/CeO₂–TiO₂ catalyst exhibited noticeably higher NO _x reduction activity at low temperatures (<250 °C). H₂-TPR revealed an increase of reducible species for the modified catalyst at basic pH, followed by neutral pH and acidic pH, respectively. High activity of the catalyst synthesized at basic pH was persistent for NO _x reduction with time that was confirmed by the time on stream durability test under SO₂ and water. The Ce 3d XPS spectra of spent catalyst synthesized at basic pH explains the gradual decrease in activity due to the decrease of Ce⁴⁺ to Ce³⁺ ratio by the formation of sulfates.     

Susceptibility of morpholine substituents to photo-oxidative decomposition-identification of photo-oxidative degradants of linezolid (PNU-100766)

Parenteral formulations of linezolid (PNU-100766), a novel (S)-3-(4′-fluorophenyl)-5-N-acetamidomethyloxazolidin-2-one antibiotic, were subjected to photo-stability testing as required by ICH guidelines. Direct, reversed phase chromatographic evaluation of the photo-irradiated solutions revealed two chromatographically broad degradants. Following preparative chromatographic isolation, the structures of both degradants were determined by mass spectrometric, nmr, and vibrational spectroscopic methods. The degradant structures formed by decomposition involving photo-oxidation of the morpholine, followed by a carbon-carbon bond scission to a formyloxyethylformamide-containing degradant. Facile hydrolytic cleav age of the formate ester in acidic media gave the second chromatographically broad degradant containing a N-2-hydroxyethylformamide group. The formamide substituent underwent further hydrolysis in acidic media to the corresponding secondary amine.     

GC/MS Analysis of Polymethoxyflavones in Citrus Oils

The cold pressed peel oils of three species of citrus fruit, viz. sweet orange, tangerine, and grapefruit, have been examined for polymethoxyflavones by GC and GC-MS. Four GC column stationary phases were compared and separation of the six predominant orange oil polymethoxyflavones was obtained isothermally at 310°C in under ten minutes, including the resolution of the polymethoxyflavones from β-sitosterol. The nature of the stationary phase and the analysis temperature exercise dramatic effects on the resolution and elution order of the components, DB-35ms providing the best overall separation. A temperature programmed separation is also presented and the polymethoxyflavone composition of all three oils, as determined by GC-MS, is described. This is the first reported GC-MS study of the PMFs of these citrus species. While tangerine oil is as rich in polymethoxyflavones as orange oil, they are less abundant and occur at lower concentrations in grapefruit oil. Hydroxy-polymethoxyflavones were identified by GC-MS in tangerine oil. One hydroxy-pentamethoxyflavone, M⁺ = 388, identified in tangerine was also present at low levels in both orange and grapefruit oils. These results are compared with previous studies utilizing HPLC and GC.     

The Effect of Sound Frequency and Intensity on Yeast Growth,Fermentation Performance and Volatile Composition of Beer

This study investigated the impact of varying sound conditions (frequency and intensity) on yeast growth, fermentation performance and production of volatile organic compounds (VOCs) in beer. Fermentations were carried out in plastic bags suspended in large water-filled containers fitted with underwater speakers. Ferments were subjected to either 200–800 or 800–2000 Hz at 124 and 140 dB @ 20 µPa. Headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) was used to identify and measure the relative abundance of the VOCs produced. Sound treatment had significant effects on the number of viable yeast cells in suspension at 10 and 24 h (p < 0.05), with control (silence) samples having the highest cell numbers. For wort gravity, there were significant differences between treatments at 24 and 48 h, with the silence control showing the lowest density before all ferments converged to the same final gravity at 140 h. A total of 33 VOCs were identified in the beer samples, including twelve esters, nine alcohols, three acids, three aldehydes, and six hop-derived compounds. Only the abundance of some alcohols showed any consistent response to the sound treatments. These results show that the application of audible sound via underwater transmission to a beer fermentation elicited limited changes to wort gravity and VOCs during fermentation.     

Cover Picture: Angew. Chem. Int. Ed. 15/2002

The cover picture shows the interior of a red‐figure kylix (440–430 BC, British Museum London) which shows the brilliant exploits of Theseus, the Greek mythology hero. In the center, Theseus is shown defeating the infamous Minataur within the labyrinth. On the right, the hero raises his hand against Sciron, below whom the turtle is visible. Next clockwise, are shown the bull of Marathon, the punishment of Sinis, the slaying of the sow Phaea, the battle of Cercyon, and finally the punishment of Procrustes. The labors of Theseus are no different from the accomplishments of today's synthetic chemists working in total synthesis. One such endeavor, the total synthesis of the CP molecules with its challenges, twists and turns, and dead‐ends, but also its rewards, is compared to the conquest of the Minotaur by Theseus in the Review by K. C. Nicolaou and P. S. Baran on p. 2678 ff.     

The Explicit Density Functional and Its Connection with Entropy Maximization

The intrinsic Helmholtz free energy, commonly used as a basis for density functional theories, is here given explicitly as a cluster diagram expansion with density field points. Also given are explicit variational procedures for determining the chemical potential for a given density, the pair potential for a given pair correlation function, and the pair correlation function for a given pair potential. The physical meaning of the density functional is established within the context of a new derivation of statistical mechanics based on entropy that supplies a variational principle for equilibrium by generalizing the thermodynamic potential to nonequlibrium states. This shows that the conventional density functional determines not only the equilibrium density, but also the probability of fluctuations about that density.