Acid, acetic phosphotungstic

To a reccHistituted, homogenized solid sample (0.5 g) or liquid sample (5.0 g), a predpitation solution (ccHitaining zinc acetate, phosphotungstic polyhydrated, and glacial acetic acid in water) was added. The mixture was vortexed, centrifuged, filtered, and injected into die LC column. 

West and Nichols in 1928 (120), starting with a commercial extract (fraction G of Cohn), and following the methods of further purification as developed by Cohn—i.e., use of basic lead acetate, phosphotungstic acid and silver, obtained a product the analyses of which they reported as ... 

TEM has been used to determine the shape and particle size of nanoparticles [27, 33]. Samples are prepared by placing a drop of preparation on copper grids, followed by negative staining with an aqueous solution of sodium phosphotungstate, phosphotungstic acid, or uranyl acetate [27, 163, 164]. Freeze fracturing with TEM has been... 

Staining techniques employing heavy metal compounds (e.g., uranyl acetate or phosphotungstic acid) as contrast agents have often been used to demonstrate the ) 2005 by CRC Press LLC... 

Jin, T.-S., Xiao, J.-C., Wang, Z.-H., Li, T.-S. Silica gel-supported phosphotungstic acid (PTA) catalyzed acylation of alcohols and phenols with acetic anhydride under mild reaction conditions. J. Chem. Res., Synop. 2003, 412-414. 

Various additives have been added to PFSA membranes to either replace the water or to retain the water at higher temperatures. Nafion has been swollen with phosphoric acid and a conductivity of 0.05 S/cm has been achieved at 150°C. Unfortimately, the anode fails after a short period of time in these membranes so no successful FC tests have been run. 1-Butyl,3-methyl imidazolium triflate and tetrafluoroborate have also been used to swell Nafion giving a conductivity of 0.1 S/cm at 180°C. Nafion has also been swollen with heterocycle solutions, imidazole, and imidazolium salts in trifluoroacetate and trifluoro methane sulfonate solution, although the reported conductivities are more modest, 10 S/cm at 100°C. Acetic acid and tetra-n-butylammonium chloride solutions of the heteropoly acid (HPA), 12-phosphotungstic acid (PTA), have all been used with Nafion giving improved FC performance at 110°C and 120°C, respectively, vs. the undoped PFSA. ... 

Grids are stained with both phosphotungstic acid and uranyl acetate in 96-well microtiter plates. To stain four grids, use a pasteur pipet to put nine drops of 95% ethanol in each of eight wells. Add three drops of the 4% phosphotungstic... 

Electron stains, used in the preparation of material for electron microscopy, are described as electron-dense as they interfere with the transmission of electrons. Examples are lead citrate, phosphotungstic acid (PTA), and uranyl acetate (UA). 

Ferric chloride hexahydrate Iron pentacarbonyl Palladium diacetate Phosphotungstic acid Vanadium pentoxide catalyst, organic synthesis Boron tribromide Boron trichloride Boron trifluoride Cobalt Mercury acetate (ic) Trimethylsilyl trifluoromethane sulfonate Zinc acetate... 

Figure 2. Electron micrograph of 1,2-dipalmitoyl-L-phosphatidylcholine stained by phosphotungstic acid(left) and dioctadecyl-dimethylammonium bromide stained by uranyl acetate(right).

Phosphotungstic acid [P2O5 24WO3 nHiO] (anionic stain) 0.5-2 6.5-7.5 Small particle, but less contrast than uranyl acetate... 

The Keggin-type phosphotungstic acid has been used to catalyse oxidation of substituted benzaldehydes by N-bromophthalimide in aqueous acetic acid, using mercury(II) as a scavenger. i Reaction rates are first-order in oxidant but fractional in aldehyde and phosphotungstate. 

One starts with an aqueous meat extract, acidifies with acetic acid, then adds phosphotungstic acid, to form a precipitate. This precipitate is treated with baryta, the mixture filtered, and the filtrate is neutralized with nitric acid. Silver nitrate is added, and the precipitate which forms is eliminated. The carnosine is precipitated from lie filtrate by the addition of silver nitrate in the presence of baryta. The precipi-... 

Microscopy techniques may also be used to perform size estimations and to corroborate the size homogeneity in a population. Transmission electronic microscopy (TEM), scanning electronic microscopy (SEM) and atomic force microscopy (AFM) are the most used. Nevertheless, these techniques are more often applied for visual characterization of size and distribution in order to corroborate data obtained with other techniques. This is because the theory behind most of the techniques used for size determination relies on the use of monodisperse and spherical particles. Any deviation from this condition may give unrealistic results that consequently may affect the efficacy of the system. In TEM measurements, a contrast agent is normally necessary for proper visualization, such as uranyl acetate, osmium tetroxide, ammonium molybdate or phosphotungstic acid. Because of its high resolution, AFM can also be useful to detect interactions between plasmids and nanostructures [77]. 

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