Search results for "Onium"
showing 10 items of 2091 documents
Ammonium ion mediated resorcarene capsules: ESI-FTICRMS study on gas-phase structure and ammonium ion affinity of tetraethyl resorcarene and its per-…
2003
AbstractThe ammonium ion binding affinities of tetraethyl resorcarene (1) and its per-methylated derivative (2) were studied by electrospray ionization Fourier transform ion cyclotron resonance (ESI-FTICR) mass spectrometry. Ten different ammonium ions were tested as guests for the resorcarenes. A strong tendency for complex formation was observed with all ammonium ions of size and charge distribution suitable for noncovalent interactions with the cavities of the resorcarene hosts 1 and 2. Although differences in ammonium ion affinities were observed between 1 and 2 due to the dissimilar conformations, the overall tendency was that increase in the degree of substitution and the length of ca…
Nontemplate Synthesis of CH3NH3PbBr3 Perovskite Nanoparticles
2014
To date, there is no example in the literature of free, nanometer-sized, organolead halide CH3NH3PbBr3 perovskites. We report here the preparation of 6 nm-sized nanoparticles of this type by a simple and fast method based on the use of an ammonium bromide with a medium-sized chain that keeps the nanoparticles dispersed in a wide range of organic solvents. These nanoparticles can be maintained stable in the solid state as well as in concentrated solutions for more than three months, without requiring a mesoporous material. This makes it possible to prepare homogeneous thin films of these nanoparticles by spin-coating on a quartz substrate. Both the colloidal solution and the thin film emit l…
Templated growth of smart coatings: Hybrid chemical vapour deposition of vanadyl acetylacetonate with tetraoctyl ammonium bromide
2009
Hybrid aerosol assisted and atmospheric pressure chemical vapour deposition methodology has been utilised to produce thin films of vanadium dioxide from vanadyl acetylacetonate. Tetraoctyl ammonium bromide (TOAB) was used in the aerosol precursor solution. The films were analysed by X-ray diffraction, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy. Their optical and thermochromic behaviour was also determined. It was found that the use of TOAB had a templating effect that led to a halving in the particle size and that this consequently led to a significant decrease in the thermochromic transition temperature of the films to 34 8C.
Templated growth of smart nanocomposite thin films: Hybrid aerosol assisted and atmospheric pressure chemical vapour deposition of vanadyl acetylacet…
2009
Hybrid aerosol assisted and atmospheric pressure chemical vapour deposition methodology has been utilised to produce nanocomposite thin films of gold nanoparticles and vanadium dioxide from vanadyl acetylacetonate and auric acid. The addition of tetraoctyl ammonium bromide (TOAB) to the precursor Solution gave control of the size and distribution of gold nanoparticles in the vanadium oxide matrix. These reactions led to vanadium dioxide films with reduced crystallite sizes and enhanced thermochromic properties. The films were analysed by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. Their optical and thermochromic behaviour was also determined, This h…
A Quantitative Estimate of Ascorbic and Isoascorbic Acid by High Performance Liquid Chromatography: Application to Citric Juices
1993
Abstract The present report deals with the optimization and verification of a simple HPLC isocratic method useful for determining ascorbic and isoascorbic acids in standard solutions and fruit juices. Sample preparation is minimal and docs not require derivatization. The method uses an octadecyl reversed phase, a mobile phase which contains cetyltrimethyl ammonium bromide 0.05M as the ionic pair and potassium dihydrogen phosphate as a buffer, at pH=4.5, and 4-hydro-xyacetanilide as internal standard. The proposed method makes it possible to quantify ascorbic and isoascorbic acid in less than 13 minutes, with precision (C. V. 3.5%) and accuracy (recover' of 98%).
CCDC 1439196: Experimental Crystal Structure Determination
2016
Related Article: Toni Mäkelä, Miia-Elina Minkkinen, and Kari Rissanen|2016|Inorg.Chem.|55|1339|doi:10.1021/acs.inorgchem.5b02780
Short Ammonium Chloride Loading Test for Evaluation of Hyperparathyroidism
1981
The dilemma in the diagnosis of hyperparathyroidism (HPT) is reflected by three factors: Hypercalcemia is still regarded as the most important diagnostic sign, but unless multiple determinations of serum calcium are done, the so-called borderline cases will be missed. Tests that readily identify HPT combine either simple performance, widespread use and low accuracy (CP, TRP, PEI, TMP/GFR)l or sophisticated methods, limited use and high accuracy (PTH, Ca+++, c-AMP). Consequently, some authors perform neck explorations to cure patients with recurrent nephrolithiasis who do not fulfill the diagnostic criteria of HPT. However, the stone recurrence rate may then reach 75%2,3 In this situation, t…
Keyhole limpet haemocyanin: negative staining in the presence of trehalose
1995
Abstract Samples of unpurified and purified haemocyanin from the giant keyhole limpet Megathura crenulata have been studied by transmission electron microscopy (TEM) using mixtures of trehalose with the negative stains, uranyl acetate and ammonium molybdate. Trehalose is a known protein preservative during air and freeze drying, UV irradiation and high temperatures, and therefore offers the possibility of protecting proteins during the drying of negatively-stained specimens and their subsequent electron microscopical study. Evidence is presented that trehalose possesses satisfactory stability within the electron beam during conventional room temperature, negative-staining studies. The combi…
Negative Staining and Cryo-negative Staining: Applications in Biology and Medicine
2013
Negative staining is widely applicable to isolated viruses, protein molecules, macromolecular assemblies and fibrils, subcellular membrane fractions, liposomes and artificial membranes, synthetic DNA arrays, and also to polymer solutions and a variety of nanotechnology samples. Techniques are provided for the preparation of the necessary support films (continuous carbon and holey/perforated carbon). The range of suitable negative stains is presented, with some emphasis on the benefit of using ammonium molybdate and of negative stain-trehalose combinations. Protocols are provided for the single droplet negative staining technique (on continuous and holey carbon support films), the floating a…
Methods of metal release assessment in soil water at anoxic sites
2006
Department of Geology, Vienna University, Vienna, Austria Metal mobility at contaminated sites can be assessed by soil water investigations or by leaching tests. Leaching tests are usually carried out in open contact with the atmosphere disregarding possible changes of redox conditions. This can affect the original metal speciation and distribution, particularly when anoxic samples are investigated. In this study, the applicability of common leaching tests (the German S4 test (S4), ammonium nitrate extraction (AmmN), and saturation soil extraction (SSE)) is tested for the assessment of zinc release from sulfide-bearing flotation residues of a former ore mine. Results are compared to soil so…