Single-walled carbon nanotubes (SWNTs) have high surface area, high adsorption ability, and nanoscale interactions. In this study, capillary columns including SWNTs, ionic liquid (IL), and IL + SWNTs for GC were prepared. The separation results showed that SWNTs possessed a wide selectivity toward alkanes, alcohols, aromatic compounds, and ketones, and a SWNT capillary column was a very useful GC column for the separation of gas samples. Coating the IL stationary phase on the SWNT capillary column, the SWNTs were able to improve chromatographic characteristic of ionic liquid. Comparing the IL coated on three graphite carbon black capillary columns, which were prepared by dynamic coating, static coating, and chemical bonding the Carbopack C with on SWNTs capillary column, the capacity factors were much higher on the SWNT column. The SEM showed that SWNTs could be bonded to the inner surface of capillary tubing, and most of them were linked end-to-end to form a layer of network structure of skeletons resulting in a high surface area, which increased the interactions between stationary phase and analytes. This is the first single-wall carbon nanotubes bonded to the fused-silica capillary tubing. In the first approach, SWNTs assist ionic liquid with enhanced chromatographic characteristic in GC. This work indicates that SWNTs make it possible to extend the application range on the newly prepared chromatographic stationary phases for GC.

Metal-organic frameworks, a new class of materials with high surface area and great porosity, have been widely applied in gas sorption. It is generally known that metal-organic framework 5 cannot be applied in aqueous phase since it is water sensitive. However, this work reveals that the derived material of metal-organic framework 5 is a good SPE sorbent that can be applied to aqueous phases. Metal-organic framework 5 was prepared and used as a SPE sorbent for the determination of polycyclic aromatic hydrocarbons in environmental matrices coupling with HPLC. The water treatment induced changes in the properties were investigated in detail. Even though metal-organic framework 5 is conversed to a second phase after water treatment, it still shows high extraction ability. Under the optimized experimental conditions, good sensitivity levels were achieved with low LODs ranging from 0.4 to 4.0 ng L(-1) and a linearity of 0.004-20 μg L(-1) (R(2) > 0.996) for the investigated polycyclic aromatic hydrocarbons. The method has been validated in the analysis of real water samples with recoveries in the range of 80.2-120.2% and RSDs in the range of 0.5-11.7%.

The inability to markedly attenuate cholesterol levels in chicken eggs has led to speculation that cholesterol is essential for yolk formation and that egg production would cease when yolk cholesterol deposition was inadequate for embryonic survival. However, this critical level hypothesis remains unproven. Here, we determine the relative responsiveness of laying hens to three select inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR), the rate-limiting enzyme of cholesterol biosynthesis. A control diet, either alone or supplemented with one of two dietary levels (0.03 or 0.06%) of atorvastatin, lovastatin, or simvastatin, was fed to White Leghorn hens for 5 wk. Liver cholesterol concentrations (mg/g tissue) were decreased (P 0.05), and 22% (P 0.05), and -3% (P > 0.05)], was much less affected. We concluded that cholesterol per se may not be an obligatory component for yolk formation in chickens and, as such, may be amenable to further pharmacological manipulation

A novel sorbent for magnetic solid-phase extraction, 1,4,7,10-tetrabenzyl-1,4,7,10-tetraazacyclododecane (TBCD) modified magnetic nanoparticles, was synthesized in this work. The four benzyl groups of TBCD provide the Fe3O4-TBCD nanoparticles with strong adsorption capacity for polycyclic aromatic hydrocarbons (PAHs) due to their π-π stacking interaction, which increases selectivity of the synthesized material to target analytes. The prepared material was characterized by scanning electron microscopy, X-ray diffraction patterns, Fourier transform infrared spectroscopy and vibrating sample magnetometry. The results indicated that the Fe3O4-TBCD nanoparticles were successfully prepared, and the particles were homogeneous nanospheres with excellent magnetic properties. Based on the optimized extraction conditions, a rapid and effective method was developed for the pre-concentration of PAHs from environmental water samples by combination with high performance liquid chromatography (HPLC). Satisfactory precision and accuracy of the developed method were obtained in a low concentration range of 0.3 ng L(-1) to 1.2 × 10(3) ng L(-1). This method produced lower limits of detection in the range of 3.0 × 10(-2) ng L(-1) to 1.2 ng L(-1). The high pre-concentration rate and efficiency of the method ensure its successful application in extraction of trace PAHs from large volumes of environmental water samples. The extraction recoveries in environmental water samples ranged from 81.1% to 115.5% with the relative standard deviations (n = 5) less than 10%.

The perovskite-type cage compound [C3H6NH2]2[KCoIII(CN)6] shows a temperature-triggered dielectric switch. The switchable properties are derived from an order–disorder phase transition of a system, by changing the motions of the polar azetidine cation guests.