Gas-solid reactions of single crystals: a study of reactions of NH3 and NO2 with single crystalline organic substrates by infrared microspectroscopy

Reaction of single crystals of benzoic and trans-cinnamic acids with 200 Torr pressure of ammonia gas in a sealed glass bulb at 20 degrees C generates the corresponding ammonium salts; there is no sign of any 1:2 adduct as has been reported previously for related systems. Isotopic substitution using ND3 has been used to aid identification of the products. Adipic acid likewise reacts with NH3 gas to form a product in which ammonium salts are formed at both carboxylic acid groups. Reaction of 0.5 Torr pressure of NO2 gas with single crystals of 9-methylanthracene and 9-anthracenemethanol in a flow system generates nitrated products where the nitro group appears to be attached at the 10-position, i.e. the position trans to the methyl or methoxy substituent on the central ring. Isotopic substitution using 15NO2 has been used to confirm the identity of the bands arising from the coordinated NO2 group. The products formed when single crystals of hydantoin are reacted with NO2 gas under similar conditions depend on the temperature of the reaction. At 20 degrees C, a nitrated product is formed, but at 65 degrees C this gives way to a product containing no nitro groups. The findings show the general applicability of infrared microspectroscopy to a study of gas-solid reactions of organic single crystals.     

A synthesis of 5-oxo-1,2,3,4-tetrahydro[1,4]azepino-[6,7,1 -kl]phenothiazine

A synthesis of a new heterocyclic system (5) is described starting from 1-carbomethoxyphenothiazine.     

Experimental measurements of non-Gaussian scattering by a fractal diffuser

We report measurements of the statistics of intensity scintillations of 10.6 μm CO₂ radiation scattered by a two-dimensional fractal phase screen. The surface profile of the phase screen is measured and shown to have a Hausdorff-Besicovitch dimension of approximately 1.4. Measurements of the on-axis intensity fluctuations as a function of illuminated spot size in both the Fresnel and Fraunhofer region are presented. This fractal scatterer does not produce the high contrast values found in speckle patterns of smoothlyvarying surfaces. Both direct and heterodyne detection results are reported. Measurements of the average intensity as a function of angle are also presented, and illustrate the failure of theoretical models which assume a Gaussian phase autocorrelation function.     

The reaction of 1,2-dioxo-1,2-dihydropyrrolo-[3,2,1-kl] phenothiazine with amines

The title compound I reacts with aliphatic amines producing ring-opened keto-amides of structure VII and with anilines forming imines of structure VIII.     

Thallation-iodination studies of heterocyclic systems

The thallation-iodination of 3-carbonylindoles ( 4a-f ) results in orientation control with substitution occurring at the 4-position ( 6a-f ). Also described is the dithallation of N-methylpyrrole-2-carboxaldehyde ( 2 ).     

Two-dimensional nitrosylated protein fingerprinting by using poly (methyl methacrylate) microchips

S-nitrosylation (also referred to as nitrosation), a reversible post translational modification (PTM) of cysteine, plays an important role in cellular functions and cell signalling pathways. Nitrosylated proteins are considered as biomarkers of aging and Alzheimer's disease (AD). Microfluidics has been widely used for development of novel tools for separation of protein mixtures. Here we demonstrate two-dimensional micro-electrophoresis (2D μ-CE) separations of nitrosylated proteins from the human colon epithelial adenocarcinoma cells (HT-29) and AD transgenic mice brain tissues. Sodium dodecyl sulphate micro-capillary gel electrophoresis (SDS μ-CGE) and microemulsion electrokinetic chromatography (MEEKC) were used for the first and second dimensional separations, respectively. The effective separation lengths for both dimensions were 10 mm, and electrokinetic injection was used with field strength at 200 V cm(-1). After 80 s separation in the first CGE dimension, fractions were successfully transferred to a second MEEKC dimension for a short 10 s separation. We first demonstrate this 2D μ-CE separation by resolving five standard proteins with molecular weight (MW) ranging from 20 to 64 kDa. We also present a high peak capacity 3D landscape image of nitrosylated proteins from HT-29 cells before and following menadione (MQ) treatment to induce oxidative stress. Additionally, to illustrate the potential of the 2D μ-CE separation method for rapid profiling of oxidative stress-induced biomarkers implicated in AD disease, the nitrosylated protein fingerprints from 11-month-old AD transgenic mice brain and their age matched controls were also generated. To our knowledge, this is the first report on 2D profiling of nitrosylated proteins in biological samples on a microchip. The characteristics of this biomarker profiling will potentially serve as the screening for early detection of AD.     

The chemisorption of carbon monoxide on Ni(110) studied by electron energy loss spectroscopy

The vibrational spectrum of carbon monoxide chemisorbed on Ni(110) at 300K has been recorded as a function of surface coverage. At low and intermediate coverage the adsorbate is bonded either to single nickel atoms (linear site) or to two nickel atoms in contact (B₂ site). As the coverage approaches unity the spectrum changes rapidly until at saturation virtually all adsorbed molecules are of B₂ type.     

Enriching carbonylated proteins inside a microchip through the use of oxalyldihydrazide as a crosslinker

We report a proof of principle study for the use of oxalyldihydrazide as a crosslinker for enrichment of carbonylated proteins within a microfluidic chip. Surface modification steps are characterized and analyzed using analytical techniques. We use oxidized cytochrome c as our model protein and demonstrate the chip's ability to capture carbonylated targets. After 100 min of continuous loading, the chip is capable of capturing 7.5 μg of carbonylated protein. All the proteins captured are eluted out of the chip using the elution protocol. Finally, we demonstrate the chip's specificity for oxidized targets by mixing oxidized cytochrome c and TRITC-BSA, with cytochrome c in low abundance. The results show that the chip is efficient at finding its target when unoxidized proteins are present. This is the first report to suggest the use of immobilized oxalyldihydrazide on a microchip as an enrichment methodology for low abundance proteins in a sample.