The solubilities of the perchlorate salts of phenyltropylium,para-methoxyphenyltropylium, andpara-dimethylaminophenyltropylium and the fluoroborate salts of Malachite Green and Crystal Violet have been determined in H2O and CH3OH. From these data the transfer Gibbs free energies from H2O to CH3OH have been calculated and compared to the predictions of Ritchie and Virtanen. The introduction of a dimethylamino substituent in thepara position of the phenyl ring substantially increases the relative stability of the cations in CH3OH compared to H2O. This observation is accounted for in terms of London dispersion forces.To whom correspondence should be addressed. 相似文献
Samples of bovine muscle, liver and urine, zeranol-free (RM 508, RM 509 and RM 510, respectively) and zeranol-containing
(RM 511, RM 512 and RM 513, respectively) were prepared and tested as candidate reference materials. Preliminary studies on
achievement of target zeranol content, intercomparison of analytical methods (HPLC-RIA and GC-MS) and effects of lyophilisation
and irradiation on zeranol content are described. The preparation of the materials and testing for homogeneity and stability
of zeranol in the materials are discussed. The coefficients of variation for zeranol determinations for between-vial homogeneity
(4.0%, 4.4% and 4.6% for muscle, liver and urine, respectively) are similar to those for the analytical method (4.0%, 7.3%
and 6.8% for muscle, liver and urine, respectively) indicating that the materials are homogeneous. Stability data over a 12-month
storage period at temperatures ranging from −18 °C to +37 °C indicate that the materials are sufficiently stable for use as
reference materials.
This paper is dedicated to the memory of Dr Hilary Stevenson (The Queen’s University of Belfast/DANI) who, together with Mr.
W. Graham, facilitated the irradiation of the lyophilised materials.-->
Received: 18 June 1996/Revised: 19 August 1996/Accepted: 23 August 1996 相似文献
We present a general theory of circular dichroism in planar chiral nanostructures with rotational symmetry. It is demonstrated, analytically, that the handedness of the incident field's polarization can control whether a nanostructure induces either absorption or scattering losses, even when the total optical loss (extinction) is polarization‐independent. We show that this effect is a consequence of modal interference so that strong circular dichroism in absorption and scattering can be engineered by combining Fano resonances with planar chiral nanoparticle clusters.
The successful inkjet printing of a cerium gadolinium oxide (Ce0.8Gd0.2O2) precursor solution on highly textured Ni-5%W is reported. A stable ink was synthesised from metal acetates and propionic
acid with rheological properties suitable for inkjet printing and also the development of solid–liquid interface comparable
with thin film formation by dip coating. Two different drop-on-demand print heads were used for deposition: a 16-nozzle piezoelectric
cartridge and a single electromagnetic nozzle. Two different rastering patterns with different droplet sizes and spacing were
compared. Thermogravimetry and X-ray diffractometry were used to study the thermal decomposition of the metal oxide precursors
and to determine the shortest possible heat treatment of the deposited layers, potentially suitable for continuous large scale
production. The results from X-ray diffraction show that the single phase Ce0.8Gd0.2O2 was obtained in all cases, but only piezoelectric inkjet printing with optimised drop overlapping produces a highly textured
buffer layer. Optical micrographs and atomic force microscopy also indicate the good quality of deposited films after heat
treatment. 相似文献
We demonstrate that the thermodynamic properties of a single liquid aerosol droplet can be explored through the combination of a single-beam gradient force optical trap with Raman spectroscopy. A single aqueous droplet, 2-6 microm in radius, can be trapped in air indefinitely and the response of the particle to variations in relative humidity investigated. The Raman spectrum provides a unique fingerprint of droplet composition, temperature, and size. Spontaneous Raman scattering is shown to be consistent with that from a bulk phase sample, with the shape of the OH stretching band dependent on the concentration of sodium chloride in the aqueous phase and on the polarization of the scattered light. Stimulated Raman scattering at wavelengths commensurate with whispering gallery modes is demonstrated to provide a method for determining the size of the trapped droplet with nanometer precision and with a time resolution of 1 s. The polarization dependence of the stimulated scatter is consistent with the dependence observed for the spontaneous scatter from the droplet. By characterizing the spontaneous and stimulated Raman scattering from the droplet, we demonstrate that it is possible to measure the equilibrium size and composition of an aqueous droplet with variation in relative humidity. For this benchmark study we investigate the variation in equilibrium size with relative humidity for a simple binary sodium chloride/aqueous aerosol, a typical representative inorganic/aqueous aerosol that has been studied extensively in the literature. The measured equilibrium sizes are shown to be in excellent agreement with the predictions of K?hler theory. We suggest that this approach could provide an important new strategy for characterizing the thermodynamic properties and kinetics of transformation of aerosol particles. 相似文献