The influence of the nature of organic phase emulsions on sensitivity in atomic-absorption determinations has been studied for the copper-APDC chelate extracted into various solvents. Oil-in-water emulsions containing 10% of organic phase emulsified with non-ionic and anionic surfactants were introduced into the flame and the atomic-absorption of copper was measured. An attempt was made to relate the effect on sensitivity to the physical properties of the different emulsions but no correlation was found. Rheological properties such as aspiration rate and nebulization efficiency did not differ significantly for different emulsified organic solvents. Enrichment of the waste solution proved the most important parameter for predicting an increase in sensitivity. 相似文献
Polyurethans with chloromethyl side chains were prepared by the polyaddition reaction of bischlorohydrins and diisocyanates. The polyurethans had inherent viscosities in a range of 0.22–0.60 and gave transparent films by solution casting. These polyurethans were easily converted to the polyoxazolidones by treatment with sodium methoxide. The polyoxazolidones had inherent viscosities up to 0.51, and gave transparent films by solution casting. 相似文献
Summary: Aerosol reactor for Electro Hydro Dynamic Atomization has been used to encapsulate water soluble proteins in poly(ε-caprolactone). As a raw material w/o emulsion of BSA water solution emulsified in the organic solution of polymer was applied. Stability of the spraying process itself for particles production was investigated. Also raw material emulsion stability has been examined and emulsion stabiliser has been found. Protein release rate from produced particles was determined. 相似文献
Retinol palmitate (vitamin A, 73.3 microg/g) in an emulsified nutritional supplement was determined by solid-phase extraction (SPE) and high-performance liquid chromatography (HPLC) with fluorescence detection (excitation 350 nm, emission 480 nm) using monosodium L-glutamate as a dissolving agent to obtain higher recovery of vitamin A from the emulsified sample solution. A Bond Elut C2 cartridge (500 mg) was chosen for SPE after comparison with 16 other types. A sample solution was applied to a conditioned Bond Elut C2 cartridge and then vitamin A was eluted with ethanol followed by HPLC. The proposed method was simple, rapid (sample preparation time by SPE: ca. 8 min, retention time: ca. 8 min), sensitive [detection limit: ca. 0.1 pg/injection (100 microl) at a signal-to-noise ratio of 3:1], highly selective and reproducible (relative standard deviation (RSD): ca. 2.9% (n = 5), between-day RSD ca. 3.7 (5 days). The recovery of vitamin A was over 90% by the standard addition method. 相似文献
This critical review focuses on the solution deposition of transparent conductors with a particular focus on transparent conducting oxide (TCO) thin-films. TCOs play a critical role in many current and emerging opto-electronic devices due to their unique combination of electronic conductivity and transparency in the visible region of the spectrum. Atmospheric-pressure solution processing is an attractive alternative to conventional vacuum-based deposition methods due to its ease of fabrication, scalability, and potential to lower device manufacturing costs. An introduction into the applications of and material criteria for TCOs will be presented first, followed by a discussion of solution routes to these systems. Recent studies in the field will be reviewed according to their materials system. Finally, the challenges and opportunities for further enabling research will be discussed in terms of emerging oxide systems and non-oxide based transparent conductors (341 references). 相似文献
To study the relationship between emulsion stability and polymer emulsifier concentration, the preparation of paraffin oil emulsions by hydroxypropyl methylcellulose (HPMC) was carried out with HPMC concentrations below the overlapping concentration (C(*)) of HPMC. The stability of the emulsions incorporating HPMC was investigated by measuring the creaming velocity, volume fraction of emulsified paraffin oil, oil droplet size, and some rheological responses such as the stress-strain sweep curve and strain and frequency dependences of dynamic viscoelastic moduli. The paraffin oil was almost emulsified by HPMC above C(*)/20: the volume fraction of paraffin oil in the emulsion was higher than 0.72. Increasing in the HPMC concentration led to decreases in both the average oil droplet size and creaming velocity and an increase in the yield stress. All emulsions behaved as solid-like viscoelastic matter. Additionally, the measured dynamic storage moduli were compared with those calculated from a relationship based on functions of the volume fraction of oil in the emulsions and Laplace pressure; good agreement between the measured and calculated moduli was obtained. On the other hand, at HPMC concentrations below C(*)/50, the emulsified paraffin oil became unstable and the oil and the HPMC solution eventually separated. 相似文献
When an emulsified 4.8 mol % LiCl-H2O solution was cooled under a pressure of 0.35 or 0.45 GPa and decompressed to 0.1 GPa at 142 K, slightly above its glass transition temperature (approximately 140 K at 0.1 GPa), its volume increased suddenly. This was regarded as an appearance of the low-density amorphous ice in the liquid solution as suggested by x-ray and Raman measurements, and this appearance corresponded to the high-to-low-density polyamorphic transition of pure H2O. Hysteresis was considered to accompany this volumetric change. The hysteresis of the liquid transition proves its first-order nature and, as for the solution, this suggests that the transition is a polyamorphic phase separation. 相似文献
Microspheres were prepared by complexation of a cationic polymer, polyquaternium-24, and an anionic surfactant, sodium lauryl sulfate (SLS). The cationic polymer solution was emulsified in dimethylsiloxane to give water in silicone emulsion (W/Si), and it was used as a template for the formation of microspheres. The emulsion was dispersed into the SLS solution. In this process, two kinds of droplets, silicone dropletes and microspheres composed of the cationic polymer and SLS, were formed, evidenced by X-ray energy dispersive spectra. The mean diameter of the microspheres was reduced from 105.7 to 64.8 mum as the stirring rate for W/Si preparation increased from 300 to 1000 rpm. It is believed that water droplets in W/Si emulsion, when exposed to SLS solution, could be solidified by the complexation of the cationic polymer and the anionic surfactant. 相似文献
A solution displaying photocontrolled transparent–opaque transition was prepared through combination of a thermosensitive polymer, poly(N-(3-ethoxypropyl)acrylamide) (PEPAAm), with α-cyclodextrin (α-CD) and a water-soluble azobenzene compound, Azo-Py+. α-CD increased the cloud point of an aqueous solution of PEPAAm through formation of inclusion complexes between α-CD and the side groups of PEPAAm. After Azo-Py+ was added, the cloud point of the solution decreased because most of the α-CD formed complexes with Azo-Py+. The concentration of free α-CD was changed by photocontrolled inclusion of Azo-Py+ in α-CD or exclusion of Azo-Py+ from α-CD, allowing the cloud point of PEPAAm/α-CD/Azo-Py+ solution to be changed up and down. Consequently, the transparent–opaque transition of this solution was realised by alternating irradiation with UV and visible light at 38°C. 相似文献
This paper deals with a method for solid-phase extraction of trace amounts of vitamin D2 (VD2, 19 ng/g) from emulsified nutritional supplements, which contain 50 kinds of compounds, followed by column-switching high-performance liquid chromatography (HPLC) with UV detection at 265 nm. VD2 is present at 1000-20,000,000 times lower concentration than other components. Bond Elut C18 cartridge was chosen as for the emulsified nutritional supplements after comparison with eight other types. A sample solution was applied to the solid-phase extraction cartridge and VD2 was eluted by methanol followed by HPLC. The effects of sample pH, eluent composition and eluate volume on the retention and elution of VD2 on Bond Elut C18 cartridge were examined. The resulting method was simple, rapid (analysis time: approximately 20 min), sensitive (detection limit: approximately 0.1 ng per injection (200 microl) at a signal-to-noise ratio 3:1), and reproducible (relative standard deviation: approximately 6.2%, n=5). The calibration graph for VD2 was linear in the range of 0.1-3 ng per injection (200 microl). Recovery of VD2 was approximately 80% by the standard addition method. 相似文献
The present paper deals with a method of solid-phase extraction of tocopherol acetate (TA, 49.6 microg/g) from emulsified nutritional supplements, which contains 50 kinds of compounds, followed by high-performance liquid chromatography (HPLC) with fluorescence detection The TA concentration is 5 to approximately 100,000 times lower than that of other compounds in the samples. Measuring the loading capacity of the larger amounts of vegetable oil onto the Bond Elut C18 cartridge was examined for the complete retention of smaller level of TA. A sample solution was applied to a solid-phase extraction cartridge and then TA was eluted by acetonitrile followed by HPLC. This method was suitable for the determination of TA in emulsified nutritional supplements. The proposed method was simple, rapid (analysis time: ca. 15 min), sensitive [detection limit: ca. 0.1 ng per injection (100 microl) at a signal-to-noise ratio of 3:1], and reproducible (relative standard deviation: ca. 2.5% (n=5)). The calibration graph of TA was linear in the range of 0.1 to 100 ng per injection (100 microl). Recovery of TA was over 90% by the standard addition method. 相似文献
Summary: After synthesizing both hard poly(organophosphazenes), which acted as strong hydrogels at a temperature below 37 °C, and soft poly(organophosphazenes), which displayed the opposite properties, we blended the polymers. When these polymers were blended at an appropriate ratio, the blended aqueous solution changed into a transparent hydrogel with improved mechanical properties at a temperature of 37 °C. According to DSC and IR measurements, the two polymers blended homogeneously and exhibited a behavior characteristic of a completely different copolymer.
An aqueous poly(organophosphazene) solution at room temperature (left) is reversibly and rapidly transformed into a transparent hydrogel at body temperature (right) when a hard poly(organophosphazene) is blended with a soft one at an appropriate ratio. 相似文献
A study on the isothermal crystallization kinetics of aqueous solution of poly (vinyl methyl ether) (PVME) was carried out by Fourier transform infrared (FTIR) and optical microscopy respectively. IR spectra of PVME solution were measured as a function of time under the isothermal crystallization conditions. With the process of crystallization, the phase of solution changes from transparent state to opaque one within around 1-2 min for 40 or 45 wt % PVME sample, the C-H symmetric stretching bands (nus(CH3)) shift to lower wave number 2823 cm(-1). The red shift of nus(CH3) absorption band was not observed in the transparent noncrystallization area. Using the temperature jump method, we determined the growth rate of ice crystal between the glass transition temperature Tg and the melting temperature Tm. At the different crystallization temperatures Tc, the different morphologies and dimension of ice crystal are also observed. 相似文献