New electrolyte systems for capillary zone electrophoresis of metal cations and non-ionic organic compounds

Capillary electrophoresis (CE) is the most attractive and very promising separation technique today due to its inherent capabilities. It is a long history from the first appearance of electrophoresis technique to modern capillary electrophoresis. Instrumental aspects concerning column techniques, injection modes and detection methods are discussed. The basic theory of capillary electrophoresis is summarized;Because traditional electrophoresis is applied mostly to biological macromolecules, so far still not many CE applications in small molecules have been published although CE is also a very promising method for the small molecules. This dissertation describes several electrolyte systems for capillary zone electrophoresis (CZE) of metal cations and non-ionic organic compounds;Transition metal ions and lanthanide ions have electrophoretic mobilities so similar that the electrophoresis of these ions is difficult. However, electrolytes containing phthalate, tartrate, lactate or [alpha]-hydroxyisobutyrate were successfully used for separation of transition metal and lanthanide ions. The separation is based on a complexing mechanism. Baseline resolution electrophoresis of 27 metal cations was achieved in six minutes using lactate electrolyte. Additional methanol in electrolytes increased resolution. Elution order of large metal ions could be changed by adding 18-crown-6. One ppm metal ions were resolved from a matrix containing 1000 ppm sodium. Quantitation of metal cations over 100-fold change in concentration was investigated. A non-complexing electrolyte, nicotinamide-formate, was developed for separations of metal cations having slow complexation kinetics;Micellar electrokinetic capillary chromatography has been used for separations of non-ionic organic compounds, but micelles disintegrate in electrolyte containing more than 20% common organic solvent. Tetraheptylammonium (THPA) was employed as an electrolyte additive for separation of hydrophobic compounds through a solvophobic association mechanism. By controlling the pH value, acetonitrile concentration and THPA concentration, hydrophobic non-ionic organic compounds were separated with high efficiency. However, THPA has a positive charge and is easy to adsorb onto capillary wall, which may cause a change in migration time. High resolution counterelectroosmotic electrophoresis of 23 neutral organics was achieved using sodium diocylsulfosuccinate (DOSS), an anionic surfactant, as a solvophobic additive. Again, pH, acetonitrile concentration, surfactant concentration and applied voltage were found to be important separation parameters. Association constants between the neutral compounds and dioctylsulfosuccinate were estimated

Thermally Self-Healing Polymeric Materials:The Next Step to Recycling Thermoset Polymers?

We developed thermally self-healing polymeric materials on the basis of furan-functionalized, alternating thermosetting polyketones (PK-furan) and bis-maleimide by using the Diels-Alder (DA) and Retro-Diels-Alder (RDA) reaction sequence. PK-furan can be easily obtained under mild conditions by the Paal-Knorr reaction of the polyketones with furfurylamine. The highly cross-linked polymers can be thermally remended to complete recovery in fracture loading, whereas the remending process can be repeated multiple times without any loss in mechanical properties. It is found that the achieved self-healing ability of this easily accessible system provides full recyclability and reworkability, which often is perceived to be difficult or impossible for thermosetting polymers. The simplicity of the synthesis, the broad range of available polyketone precursors, and the striking healing ability (kinetics and efficiency of mechanical properties recovery) of this system could expand the scientific understanding of self-healing materials and introduce the cradle-to-cradle concept for thermoset-based plastics and composites

A New variant of Van Leer's method for multidimensional systems of conservation laws

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Role of the hydrophobic domain in targeting caveolin-1 to lipid droplets

Although caveolins normally reside in caveolae, they can accumulate on the surface of cytoplasmic lipid droplets (LDs). Here, we first provided support for our model that overaccumulation of caveolins in the endoplasmic reticulum (ER) diverts the proteins to nascent LDs budding from the ER. Next, we found that a mutant H-Ras, present on the cytoplasmic surface of the ER but lacking a hydrophobic peptide domain, did not accumulate on LDs. We used the fact that wild-type caveolin-1 accumulates in LDs after brefeldin A treatment or when linked to an ER retrieval motif to search for mutants defective in LD targeting. The hydrophobic domain, but no specific sequence therein, was required for LD targeting of caveolin-1. Certain Leu insertions blocked LD targeting, independently of hydrophobic domain length, but dependent on their position in the domain. We propose that proper packing of putative hydrophobic helices may be required for LD targeting of caveolin-1

Rapid and Efficient Extraction and HPLC Analysis of Sesquiterpene Lactones from Aucklandia lappa Root.

The root of Aucklandia lappa Decne, family Asteraceae, is widely used in Asian traditional medicine due to its sesquiterpene lactones. The aim of this study was the development and optimization of the extraction and analysis of these sesquiterpene lactones. The current Chinese Pharmacopoeia reports a monograph for "Aucklandiae Radix", but the extraction method is very long and tedious including maceration overnight and ultrasonication. Different extraction protocols were evaluated with the aim of optimizing the maceration period, solvent, and shaking and sonication times. The optimized method consists of only one hour of shaking plus 30 minutes of sonication using 100% MeOH as solvent. 1H NMR spectroscopy was used as a complementary analytical tool to monitor the residual presence of sesquitepene lactones in the herbal material. A suitable LC-DAD method was set up to quantify the sesquiterpene lactones. Recovery was ca. 97%, but a very high instability of constituents was found after powdering the herbal drug. A loss of about 20% of total sesquiterpenes was found after 15–20 days; as a consequence, it is strongly endorsed to use fresh powdered herbal material to avoid errors in the quantification

Experimental Infection of Rabbits with Rabbit and Genotypes 1 and 4 Hepatitis E Viruses

Background: A recent study provided evidence that farmed rabbits in China harbor a novel hepatitis E virus (HEV) genotype. Although the rabbit HEV isolate had 77-79% nucleotide identity to the mammalian HEV genotypes 1 to 4, their genomic organization is very similar. Since rabbits are used widely experimentally, including as models of infection, we investigated whether they constitute an appropriate animal model for human HEV infection.Methods: Forty-two SPF rabbits were divided randomly into eleven groups and inoculated with six different isolates of rabbit HEV, two different doses of a second-passage rabbit HEV, and with genotype 1 and 4 HEV. Sera and feces were collected weekly after inoculation. HEV antigen, RNA, antibody and alanine aminotransferase in sera and HEV RNA in feces were detected. The liver samples were collected during necropsy subject to histopathological examination.Findings: Rabbits inoculated with rabbit HEV became infected with HEV, with viremia, fecal virus shedding and high serum levels of viral antigens, and developed hepatitis, with elevation of the liver enzyme, ALT. The severity of disease corresponded to the infectious dose (genome equivalents), with the most severe hepatic disease caused by strain GDC54-18. However, only two of nine rabbits infected with HEV genotype 4, and none infected with genotype 1, developed hepatitis although six of nine rabbits inoculated with the genotype 1 HEV and in all rabbits inoculated with the genotype 4 HEV seroconverted to be positive for anti-HEV IgG antibody by 14 weeks post-inoculation.Conclusions: These data indicate that rabbits are an appropriate model for rabbit HEV infection but are not likely to be useful for the study of human HEV. The rabbit HEV infection of rabbits may provide an appropriate parallel animal model to study HEV pathogenesis