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A previous population genetic study of European populations of Grass of Parnassus/Bog-stars Parnassia palustris based on enzyme markers is summarized and some of the results are highlighted. Diploid populations showed similar levels of genetic diversity all over Europe. Northern populations have apparently been established through the gradual advance of genetically variable populations and variation at individual loci indicate migration routes from both south-southwest and east-northeast in Fennoscandia. Furthermore, the data strongly support a repeated autoploid origin of the tetraploid cytotype which has successfully colonized new land since the last ice age. Source

Gong X.,East China Normal University | Hansen E.W.,UiO | Chen Q.,East China Normal University
Macromolecular Chemistry and Physics | Year: 2011

A log/normal MWD is characterized by two parameters, its mean molecular weight M0 and width σ. It is demonstrated how these parameters can be obtained by model fitting a stretched exponential function (SEF), as characterized by two parameters β and DS, to the PGSTE response curve. Based on simulations, two general empirical equations relating β and DS to M0 and σ are found. The model enables the MWD characteristics to be determined if the scaling law between diffusivity and molecular weight is known. The sensitivity and relative error of σ and M0 are discussed and the applicability of the model is illustrated by analyzing experimental NMR response curve of some PEO samples. The key advantages of this technique are its simplicity, numerical robustness, and reliability. It is demonstrated how PGSE NMR data can be used to derive MW and MWD of a polymer sample. The sensitivity and relative error of the method are discussed, and its applicability is illustrated by analyzing the experimental NMR response curve of three PEO samples. The method is shown to be simple, numerically robust, and reliable. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Hansen E.W.,UiO | Gong X.,East China Normal University | Chen Q.,East China Normal University
Macromolecular Chemistry and Physics | Year: 2013

A compressed exponential function (CEF) is shown to be represented by a distribution of Gaussian functions. The properties and characteristics of the distribution are detailed and discussed, and are illustrated with reference to the change in the NMR spectroscopy proton Hahn echo relaxation response that takes place in a composite material (prepared by melt compounding a mixture of graphite nanoparticles and pyromellitic anhydride modified polypropylene carbonate (PPC)) during aging at 90 °C. The results show that both the width and the average value of the spin-spin relaxation rate distribution decrease during aging, suggesting that the molecular motion becomes less constrained and less heterogeneous. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

News Article
Site: http://onlinelibrary.wiley.com/resolve/doi?DOI=10.1002%2F%28ISSN%291616-3028

Physical delivery of anticancer drugs in controlled anatomic locations can complement the advances being made in chemo-selective therapies. To this end, an optical fiber catheter is coated in a thin layer of metal organic framework UiO-66 and the anticancer drug 5-Fluorouracil (5-FU) is deposited within the pores. Delivery of light of appropriate wavelength through the fiber catheter is found to trigger the release of 5-FU on demand, offering a new route to localized drug administration. The system exhibits great potential with as much as 110 × 10−6 m of 5-FU delivered within 1 min from one fiber.

Imagine a power plant that takes the excess carbon dioxide (CO ) put in the atmosphere by burning fossil fuels and converts it back into fuel. Now imagine that power plant uses only a little water and the energy in sunlight to operate. The power plant wouldn't burn fossil fuels and would actually reduce the amount of CO in the atmosphere during the manufacturing process. For millions of years, actual plants have been using water, sunlight, and CO to create sugars that allow them to grow. Scientists around the globe are now adopting their energy-producing behavior. "We're trying to speed up the natural carbon cycle and make it more efficient," said Karl Johnson, the William Kepler Whiteford Professor in the Department of Chemical & Petroleum Engineering at the University of Pittsburgh and principal investigator of the study. "You don't have to waste energy on all the extra baggage it takes to grow plants, and the result is a man-made carbon cycle that produces liquid fuel." There's one catch. CO is a very stable molecule, and enormous amounts of energy are required to get it to react. One common way to make use of excess CO involves removing an oxygen atom and combining the remaining CO with H to create methanol. However, during this process parts of the conversion reactor need to heat as high as 1000 degrees Celsius, which can be difficult to sustain, especially when the only energy source is the sun. A catalyst can get the CO to react at much lower temperatures. Some researchers have been experimenting with different materials that can get the CO to split—even at room temperature. But these, and most, reactive catalysts already identified are too expensive to mass-produce, and fossil fuels still offer a cheap source of energy. The low price and abundance of fossil fuels prevents a lot of companies from investing in the expensive trial and error process of researching new catalysts. The study, "Screening Lewis Pair Moieties for Catalytic Hydrogenation of CO2 in Functionalized UiO-66" provides researchers with a good idea of how they should start looking for an optimal catalyst. Johnson, along with study co-author and post-doctoral researcher Jingyun Ye at the University of Pittsburgh, examined a series of eight different functional groups of Lewis acid and base pairs (Lewis pairs for short), which are highly reactive compounds often used as catalysts. They found that the two factors qualifying a material as a good catalyst are its hydrogen adsorption energy and the Lewis pair's hardness—a measurement of the difference between its ionization potential and electron affinity. Using this framework, Johnson plans to work with experimentalists to screen for catalysts more effectively, and hopefully, bring researchers closer to creating power plants that create liquid fuel while reducing atmospheric CO . Imagine contributing to the reduction of CO in the atmosphere every time you fill up your gas tank. Explore further: Too green to be true? Researchers develop highly effective method for converting CO2 into methanol More information: Screening Lewis Pair Moieties for Catalytic Hydrogenation of CO2 in Functionalized UiO-66, ACS Catalysis, DOI: 10.1021/acscatal.5b01191

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