Insights into the Catalytic Activity of Nitridated Fibrous Silica (KCC‐1) Nanocatalysts from 15N and 29Si NMR Spectroscopy Enhanced by Dynamic Nuclear Polarization

Fibrous nanosilica (KCC‐1) oxynitrides are promising solid‐base catalysts. Paradoxically, when their nitrogen content increases, their catalytic activity decreases. This counterintuitive observation is explained here for the first time using ¹⁵N‐solid‐state NMR spectroscopy enhanced by dynamic nuclear polarization.     

A cold thermionically emitting dusty air plasma formed by radiativeheating of graphite particulates

Formation of an atmospheric pressure dusty air plasma is explored experimentally in this paper. The plasma is created by seeding an air flow with graphite particles and irradiating the particulates with a focused CO₂ laser beam. The graphite particles are, thus, heated to thermionically emitting temperatures, and average particle temperatures and average particle number densities are measured. The presence of charges is inferred both from these measured quantities using a simple theoretical transient model, and experimentally by applying a dc bias across the irradiated region. It is found that an electron density of ~6.7 × 10⁵ cm^-3 (6.7 × 10¹¹ m^-3) can be produced at steady state in the presence of O₂. This value can be increased to 3.6 × 10⁷ cm^-3 (3.6 × 10¹³ m ^-1) in the ideal case where an electron attachment to O₂ is suppressed and where a lower work function particulate is used     

Gasuntersuchungen

Ohne Zusammenfassung     

Solid-phase synthesis of 2,3-diphenylpropionic acid library as VLA-4 antagonists

2,3-Diphenylpropionic acid library for VLA-4 antagonist was synthesized on solid-phase. Comparison of the two synthetic routes via an orthogonal generation of two aromatic amino functional groups are discussed. From this work, several compounds were identified as potent VLA-4 antagonists.     

Determination of total fluorine in vegetables and plants by open-flame ashing and microdiffusion : Comparison with furnace ashing and oxygen-flask combustion

The sample is ashed in a nickel crucible over an open flame with calcium hydroxide as the fixative; fluoride is separated by micro-diffusion and measured with a fluoride-selective electrode. The calcium hydroxide fixative permits a temperature of 800–850°C during the final ashing, so that insoluble silicates are decomposed and fluoride is converted to an acid-soluble form. Other advantages over furnace ashing at 600°C are less contamination and more rapid ashing (20 min compared to 6 h). The interference of aluminium and silica on microdiffusion was studied: perchloric acid was found to be preferable to sulphuric acid as medium. A new way for preparing calcium hydroxide suspension, low in fluoride, is described. The values found by the proposed method generally compare well with those obtained by oxygen flask combustion. Direct diffusion (i.e. without ashing) gave much lower values than the ashing methods, except for tea leaves.