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21.
Neymara C. Nepomuceno Amelia S. F. Santos Juliano E. Oliveira Gregory M. Glenn Eliton S. Medeiros 《Cellulose (London, England)》2017,24(1):119-129
Cellulose nanowhiskers were extracted from the spines of Mandacaru (Cereus jamacaru DC.), a cactus native to the Caatinga biome of northeastern Brazil, using sulfuric acid hydrolysis preceded by alkaline treatment and bleaching. Results showed that three bleaching steps were required to remove most of the non-cellulosic constituents of the spines that yielded 77.4% cellulose. Nanowhiskers size decreased from about 400 to 260 nm when extraction time varied from 60 to 120 min, this was also evidenced by X-ray diffraction. Alkaline treated and bleached samples had lower thermal stability as compared to untreated spines due to removal of lignin and increased surface area. The amount of time samples were treated with sulfuric acid influenced the thermal stability and consequently the degree of crystallinity of the nanowhiskers. Cellulose nanowhiskers were obtained from Mandacaru spines providing a new renewable source of reinforcement with potential applications in nanocomposites. 相似文献
22.
Silvana V. Rodrigues Decio Nepomuceno Luci Viana Martins W. Baumann 《Fresenius' Journal of Analytical Chemistry》1998,360(1):58-61
The solubility of two related series of each three triazine compounds has been determined in supercritical CO2, at 40 °C and pressures between 80 and 220⋅105 Pa. A high pressure small volume cell with adjustable optical path and built-in circulation pump has been constructed to
be used with quartz windows in a Perkin Elmer UV-VIS spectral photometer. At 220 bar solubilities are between 0.3 and 25 g/L,
dependent on the specific triazine structure. The isothermal pressure dependence of the solubility could be modelled using
the pressure dependent dielectric constant of CO2 as the only variable.
Received: 30 October 1996/Revised: 3 April 1997/Accepted: 13 April 1997 相似文献
23.
Hawkridge AM Nepomuceno AI Lovik SL Mason CJ Muddiman DC 《Rapid communications in mass spectrometry : RCM》2005,19(7):915-918
We report an evaluation of a modern Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) instrument to determine the general trend of post-excitation radius on total ion abundance, mass measurement accuracy, and isotopic distributions for internally calibrated mass spectra. The optimum post-excitation radius was determined using total ion abundance, mass measurement accuracy (MMA), and isotope ratios. However, despite the utility of internal calibration for achieving ultimate MMA, the internal calibrant ions were insufficient for compensating for sub-optimum ICR cell conditions. The findings presented herein underscore the importance of determining the optimal post-excitation radius in FT-ICR-MS to achieve high ion abundance (low limits of detection), high MMA, and valid isotopic distributions. 相似文献
24.
This work introduces a new high-throughput screening particle - a Dallas Amphorous Material No. 1 (DAM-1) molecular sieve particle. In contrast to porous silica microspheres, the 2-8-microm sized DAM-1 molecular sieve particles are available in a variety of shapes and morphologies including spheres, hexagons, rods, gyroids, and discoids. The advantage of using DAM-1 molecular sieve particles is the ability to encode an array by particle shape, which in turn permits the repeated use of luminescent reporter dyes. In this technical note, we demonstrate optical decoding of fluorescein- and Texas Red-modified shaped molecular sieve particles using reflectance and fluorescence microscopies. 相似文献