112 research outputs found

    Chiroptical properties of an alternatingly functionalized cellotriose bearing two porphyrin groups.

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    Right-handedness derived from bisporphyrins attached to a cellotriose backbone at O-6 and O''-6 positions is revealed for the first time. This cellotriose is proposed as a model of alternatingly functionalized cellulosics, which have promising properties for applications in optoelectronics and molecular receptors owing to the chirality and rigid backbone effects

    Incremented alkyl derivatives enhance collision induced glycosidic bond cleavage in mass spectrometry of disaccharides

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    Electrospray ionization and collision induced dissociation on a triple quadrupole mass spectrometer were used to determine the effect of spatial crowding of incremented alkyl groups of two anomeric pairs of peralkylated (methyl to pentyl) disaccharides (maltose/cellobiose and isomaltose/gentiobiose). Protonated molecules were generated which underwent extensive fragmentation under low energy conditions. For both the 1 → 4 and 1 → 6 α and β isomers, at comparable collision energies the methyl derivative exhibited the least fragmentation followed by ethyl, propyl, butyl, and pentyl. Collision energy is converted to rotational-vibrational modes in competition with bond cleavage, as represented by the slope of product/parent ion (D/P) ratio versus offset energy. Variable rotational freedom at the glycosidic linkage with incremented alkyl groups is hypothesized to be responsible for this effect. Discrimination of anomeric configuration was also assessed for these stereoiosmeric disaccharides. A systematic study showed that an increasing discrimination was attained for the 1 → 4 isomeric pair as the size of the derivative increased from methyl to pentyl. No anomeric discrimination was attained for the 1 → 6 isomeric pair. Parent and product ion scans confirmed the consistency of fragmentation pathways among derivatives. Chem-X and MM3 molecular modeling programs were used to obtain minimum energy structures and freedom of motion volumes for the permethylated disaccharides. The modeling results correlated with the fragmentation ratios obtained in the mass spectrometer giving strong indication that the collision induced spectra are dependent on the freedom of rotational motion around the glycosidic bond. © 2003 American Society for Mass Spectrometry

    The Lantern Vol. 4, No. 2, March 1936

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    • Cooperative Democracy • Fantasy • Drama: Porgy and Bess • Foreign Entanglements • The Kibitzer • My Gallery of Old Folks • My Friend, Mark Twain • Jimmy and Waffles • Reminiscence • Gold Dust • After Twenty Centuries • All the World\u27s a Stage • Early Medicinehttps://digitalcommons.ursinus.edu/lantern/1007/thumbnail.jp

    The Lantern Vol. 5, No. 3, May 1937

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    • Dedication • Dr. McClure: An Ursinus Man • Roar, O Wind! • To the Ladies! • The Futility of Dying • The Symbolism of the British Crown • Oh! • It Might Have Been • Treat Yourself? • Three Writers • Hawaii in June • On Being a Twin • Black Magic • Triangle • Who Longs? • A Son Passes • Sing an Old-Fashioned Song • Questioning • An Argument About a Fish • That Morning Eye-Opener • Scoop for the Sun • The Dead Do Not Die Once • Give Us Timehttps://digitalcommons.ursinus.edu/lantern/1010/thumbnail.jp

    Longitudinal Molecular Trajectories of Diffuse Glioma in Adults

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    The evolutionary processes that drive universal therapeutic resistance in adult patients with diffuse glioma remain unclear ¹² . Here we analysed temporally separated DNA-sequencing data and matched clinical annotation from 222 adult patients with glioma. By analysing mutations and copy numbers across the three major subtypes of difuse glioma, we found that driver genes detected at the initial stage of disease were retained at recurrence, whereas there was little evidence of recurrence-specifc gene alterations. Treatment with alkylating agents resulted in a hypermutator phenotype at diferent rates across the glioma subtypes, and hypermutation was not associated with diferences in overall survival. Acquired aneuploidy was frequently detected in recurrent gliomas and was characterized by IDH mutation but without co-deletion of chromosome arms 1p/19q, and further converged with acquired alterations in the cell cycle and poor outcomes. The clonal architecture of each tumour remained similar over time, but the presence of subclonal selection was associated with decreased survival. Finally, there were no differences in the levels of immunoediting between initial and recurrent gliomas. Collectively, our results suggest that the strongest selective pressures occur during early glioma development and that current therapies shape this evolution in a largely stochastic manner

    Disclosure and rationality: Comparative risk information and decision-making about prevention

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    With the growing focus on prevention in medicine, studies of how to describe risk have become increasing important. Recently, some researchers have argued against giving patients "comparative risk information," such as data about whether their baseline risk of developing a particular disease is above or below average. The concern is that giving patients this information will interfere with their consideration of more relevant data, such as the specific chance of getting the disease (the "personal risk"), the risk reduction the treatment provides, and any possible side effects. I explore this view and the theories of rationality that ground it, and I argue instead that comparative risk information can play a positive role in decision-making. The criticism of disclosing this sort of information to patients, I conclude, rests on a mistakenly narrow account of the goals of prevention and the nature of rational choice in medicine

    Populist Mobilization: A New Theoretical Approach to Populism*

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/112280/1/j.1467-9558.2011.01388.x.pd
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