Search results for "COLUMN"
showing 10 items of 1301 documents
Bomberos pirómanos (1)
2008
Observations on mucus aggregates along Sicilian coasts during 1991–1992
1995
Abstract The results of some observations on gelatinous material accumulating on the sea ground and free floating in the water column along Sicilian coasts are reported. The phenomenon showed different development patterns moving from the Tyrrherian to the Jonian coast and to the Sicilian Channel. Moreover, in 1991, mucus aggregates in the Tyrrhenian sea showed a similar structure, behaviour and origin to those observed in the Adriatic sea, whereas, in 1992, only a massive growth of metaphytic threadlike algae, more or less producing gelatinous sheaths, occurred.
Synthesis and Characterization of Fluorescent, Low-Symmetry Triphenylene Discotic Liquid Crystals: Tailoring of Mesomorphic and Optical Properties
1996
A series of monofunctionalized triphenylene-based discotic liquid crystals were synthesized starting from 2-hydroxy-3,6,7,10,11-pentakis(pentyloxy)triphenylene. These compounds are unique in that they possess a single electron-withdrawing group (and consequently a large dipole moment) connected directly to the polyaromatic core. All of the new liquid crystals show a significantly broader range of mesogenicity relative to the parent compound 2,3,6,7,10,11-hexakis(pentyloxy)triphenylene. Moreover, some of the new mesogens exhibit a more ordered mesophase relative to the hexagonal columnar phase (Dh) at lower temperatures. Monofunctionalization of the triphenylene core has a dramatic effect on…
On-line gradient liquid chromatography–Fourier transform infrared spectrometry determination of sugars in beverages using chemometric background corr…
2008
Abstract An on-line gradient reversed phase liquid chromatography–Fourier transform infrared spectrometry (LC–FTIR) method was developed for the determination of fructose, glucose, sucrose and maltose in beverages. Improved chromatographic resolution was obtained using a linear gradient from 75 to 55% (v/v) acetonitrile in water in 15 min. Changes in the background spectra were corrected employing “univariate background correction based on the use of a reference spectra matrix” (UBC-RSM) and using the ratio of absorbance (AR) at 2256 and 2253 cm −1 for the identification of the eluent spectra within the RSM. The method provided limits of detection in the order of 0.75 mg ml −1 . The precisi…
Catastrophic effects of sand mining on macroinvertebrates in a large shallow lake with implications for management
2019
Sand mining is a human activity that is increasing in inland waters and has profound effects on entire aquatic ecosystems. However, current knowledge of the effects of sand mining on freshwater lake ecosystems remains limited, especially for biotic communities. Here, we investigated the responses of macroinvertebrates to indiscriminate sand mining in a large shallow lake of China. Our results indicated that sand mining significantly increased the content of suspended particulate matter, total nitrogen, total phosphorus and chlorophyll a in the water column both in the sand mining area and the area adjacent to the dredging activities. While there was significantly lower total nitrogen and th…
Absolute optical chiral analysis using cavity-enhanced polarimetry
2021
Chiral analysis is central for scientific advancement in the fields of chemistry, biology, and medicine. It is also indispensable in the development and quality control of chiral compounds in the chemical and pharmaceutical industries. Current methods for chiral analysis, namely optical polarimetry, mass spectrometry and nuclear magnetic resonance, are either insensitive, have low time resolution, or require preparation steps, and so are unsuited for monitoring chiral dynamics within complex environments: the current need of both research and industry. Here we present the concept of absolute optical chiral analysis, as enabled by cavity-enhanced polarimetry, which allows for accurate unambi…
Enantiomer Separations Using Designed Imprinted Chiral Phases
2003
Total Synthesis of (±)-Oxalicumone C and Chiral Resolution and Elucidation of Its Absolute Configuration
2014
The racemic total synthesis, the chiral resolution, and the elucidation of the absolute configuration of the natural product oxalicumone C were investigated. The goal was achieved by a synthetic strategy beginning with the synthesis of a 5-hydroxy-7-methylchromone precursor. Further modification possibilities were achieved by introduction of a vinyl moiety into the chromone, which was based on a selective iodination step in the 3-position. Further transformations furnished the racemic natural product. To determinate the absolute configuration of naturally occurring oxalicumone C, both enantiomers were separated by chiral HPLC. Comparison of the calculated and experimental vibrational circul…
BONDED SILICA PHASES FOR THE SEPARATION OF BIOPOLYMERS BY MEANS OF COLUMN LIQUID CHROMATOGRAPHY
1988
Is multidimensional high performance liquid chromatography (HPLC) an alternative in protein analysis to 2D gel electrophoresis?
2000
The interactive modes of High Performance Liquid Chromatography (HPLC) of proteins provide a platform for the construction of a multidimensional HPLC system coupled to mass spectrometry. We present a system composed of both anion and cation exchanger columns, in the first dimension, and n-octadecyl bonded 1.5 μm nonporous silica columns in the second dimension. Both columns are operated under gradient conditions. A system suitability test with standard proteins showed that the total analysis can be performed within about 20 minutes. The fractions taken from the ion exchanger column are directly analyzed within one minute on the reversed phase column at a high flow rate. Two reversed phase c…