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First Observation of Be-15
Get PDFThe neutron-unbound nucleus Be-15 was observed for the first time. It was populated using neutron transfer from a deuterated polyethylene target with a 59 MeV/u Be-14 beam. Neutrons were measured in coincidence with outgoing Be-14 particles and the reconstructed decay energy spectrum exhibits a resonance at 1.8(1) MeV. This corresponds to Be-15 being unbound by 0.45 MeV more then Be-16 thus significantly hindering the sequential two-neutron decay of Be-16 to Be-14 through this state
Hydrogen Evolution Reaction Measurements of Dealloyed Porous NiCu
Get PDFPorous metals are of interest for their high surface area and potential for enhanced catalytic behavior. Electrodeposited NiCu thin films with a range of compositions were electrochemically dealloyed to selectively remove the Cu component. The film structure, composition, and reactivity of these samples were characterized both before and after the dealloying step using scanning electron microscopy, energy-dispersive spectroscopy, and electrochemical measurements. The catalytic behavior of the dealloyed porous Ni samples towards the hydrogen evolution reaction was measured and compared to that of the as-deposited samples. The dealloyed samples were generally more reactive than their as-deposited counterparts at low overpotentials, making the dealloying procedure a promising area of exploration for improved hydrogen evolution catalysts
Phylogenetics And Biogeography Of Theaceae Based On Sequences Of Plastid Genes
No full textDespite several morphological and molecular analyses of Theaceae, several outstanding issues remain in the phylogenetics and biogeography of the family including the disputed relationships among the tribes Gordonieae, Stewartieae, and Theeae, the controversial taxonomic status of Hartia and Stewartia, and the unclear biogeographic history of Gordonieae and Stewartieae. In this study we gathered DNA sequences of multiple plastid genes from 27 species of Theaceae representing all genera except Laplacea, conducted phylogenetic analyses using parsimony, likelihood, and Bayesian methods, and estimated divergence times within a Bayesian framework with fossil calibrations and molecular data. Our data provided further support for the three tribes in the family and for the sister-group relationship of Theeae to Stewartieae plus Gordonieae. Within Gordonieae, our study for the first time offered strong molecular support for the sister relationship of Franklinia and Schima. Within Stewartieae, our data supported the paraphyly of Stewartia including Hartia. Within Stewartia, our data for the first time suggested that North American (NA) species Stewartia ovata was more closely related to eastern Asian (EA) species than to the other NA species Stewartia malacodendron. Biogeographic analyses indicated that disjunct endemic species of Gordonieae might have originated from NA and those of Stewartieae from EA. Divergence times of the EA-NA disjunct pairs identified in this study (Franklinia and Schima in Gordonieae and S. ovata (NA) and Asian species of Stewartia) were estimated to be in the Mid-Miocene. Population exchanges in Gordonieae and Stewartieae may have occurred over the Bering land bridge prior to the Mid-Miocene
Design, Synthesis, And Dna Binding Characteristics Of A Group Of Orthogonally Positioned Diamino, N-formamido, Pyrrole- And Imidazole-containing Polyamides
No full textOrthogonally positioned diamino/dicationic polyamides (PAs) have good water solubility and enhanced binding affinity, whilst retaining DNA minor groove and sequence specificity compared to their monoamino/monocationic counterparts. The synthesis and DNA binding properties of the following diamino PAs: f-I (P) under barI (3a), f-I (P) under barP (4), f-(P) under bar IP (5), and f-P (P) under barP (6) are described. (P) under bar denotes the site where a 1-propylamino group is attached to the NI-position of the heterocycle. Binding of the diamino PAs to DNA was assessed by DNase I footprinting, thermal denaturation, circular dichroism titration, biosensor surface plasmon resonance (SPR), and isothermal titration calorimetry (ITC) studies. According to SPR studies, f-I (P) under barI (3a) bound more strongly (K-eq = 2.4 x 10(8) M-1) and with comparable sequence selectivity to its cognate sequence 5\u27-ACGCGT-3\u27 when compared to its monoamino analog f-IPI (1). The binding of f-I (P) under barI (3a) to 5\u27-ACGCGT-3\u27 via the stacked dimer motif was balanced between enthalpy and entropy, and that was quite different from the enthalpy-driven binding of its monoamino parent f-IPI (1). f-I (P) under barP (4) also bound more strongly to its cognate sequence 5\u27-ATGCAT-3\u27 (K-eq = 7.4 x 10(6) M-1) via the side-by-side stacked motif than its monoamino analog f-IPP (2a). Although f-P (P) under barP (6) bound via a 1:1 motif, it bound strongly to its cognate sequence 5\u27-AAATTT-3\u27 (K-eq = 4.8 x 10(7) M-1), 15-times higher than the binding of its monoamino analog f-PPP (2c), albeit f-PPP bound via the stacked motif. Finally, f-(P) under bar IP (5) bound to its target sequence 5\u27-ATCGAT-3\u27 as a stacked dimer and it has the lowest affinity among the diamino PAs tested (K-eq10(5) M-1). This was about two times lower in affinity than the binding of its monoamino analog f-PIP (2b). The results further demonstrated that the \u27core rules\u27 of DNA recognition by monoamino PAs also apply to their diamino analogs. Specifically, PAs that contain a stacked IP core structure bind most strongly (highest binding constants) to their cognate GC doublet, followed by the binding of PAs with a stacked PP structure to two degenerate AT base pairs, and finally the binding of PAs with a PI core to their cognate CG doublet. (C) 2013 Elsevier Ltd. All rights reserved
Dune Complexes Along The Southeastern Shore Of Lake Michigan: Geomorphic History And Contemporary Processes
No full textThis field guide explores the geomorphology, ecology, contemporary processes, sedimentary structures, and geomorphic history of the large freshwater dune systems on the southeastern shore of Lake Michigan. Recent research studies on varying aspects of the dunes are highlighted at each stop. From north to south, these stops include P.J. Hoffmaster State Park near Muskegon, Michigan; Gilligan Lake and Green Mountain Beach southwest of Holland, Michigan; Saugatuck Dunes State Park and Saugatuck Harbor Natural Area, both near Saugatuck, Michigan; Warren Dunes State Park and Grand Mere State Park between the Indiana–Michigan border and Benton Harbor, Michigan; and Mount Baldy on the eastern edge of the Indiana Dunes National Lakeshore, Indiana. All of the complexes described are low perched transgressive dune complexes that are migrating inland over former lake plains or baymouth bars. Moving from the lake inland, the typical dune complex in this area consists of incipient foredunes, an established foredune ridge, a parabolic dune complex, and a back-dune ridge complex. All stages of ecological succession—beginning with a pioneer community dominated by beach grasses and ending with a mesic forest dominated by oak, maple, and beech—are typically present in the larger dune complexes. Like coastal dunes everywhere, surface changes in Lake Michigan dunes are driven by spatial gradients in sand flux, which, in turn, are determined by a complex interaction among wind, vegetation patterns, and preexisting topography. The patterns of surface change are modified by seasonal effects, with the majority of sand transport being associated with strong storms in the autumn, winter, and early spring. Sand can be temporarily stored in niveolian deposits during the winter, leading to oversteepened slopes, which collapse during the spring thaw. A variety of sedimentary bed forms and structures can be viewed in dunes along the southeastern shore of Lake Michigan, including wind ripples, lag deposits, raindrop impressions, adhesion ripples, adhesion warts, eolian turrets, sand pedestals, surface patches of fine-grained dark sand, pinstripes, paleosols, cross-bedding, climbing ripple lamination, niveolian deposits, and avalanche lobes. Most of these features are best seen immediately after strong storms in the autumn and winter. Remnants of older dune surfaces are exposed in a few places in back-dune ridge complexes; however, the current dune complexes are largely a product of events that occurred during and after the rise in lake levels to the Nipissing peak (ca. 4.5 ka). Broad fields of relatively low dunes developed during the drop in lake levels following the Nipissing peak. Beginning with the rise to the Algoma high lake level (ca. 3.2 ka), the lakeward edges of these fields were episodically reworked, forming the large parabolic dune complexes. A period of widespread dune stability resulted in the development of the Holland Paleosol, a particularly well-developed paleosol with Spodosol characteristics. Widespread dune growth and migration resumed prior to European settlement of the area and continue today
BrowZine: Academic Journals on Your Tablet
Get PDFWith the decline of print journals, researches have lost the ability to stay abreast of research in their discipline by browsing the journal literature. BrowZine is an iPad/Android App that collects journal articles from library databases and repackages them into browsable journal issues, normalizing the browsing and reading experience
Near-barrier Fusion and Total Reaction of a Proton-rich Projectile: He-3+Ni-58
No full textEvaporation protons from the fusion of the 3He+58Ni system were measured at three energies near but above the Coulomb barrier. The respective elastic scattering angular distribution was also determined for one of these energies. The fusion data, after being properly reduced to eliminate size and charge effects, are compared to the recently measured fusion excitation function for the proton-halo system 8B+58Ni. As a reference, fusion data for the 16O+58Ni system are also presented. With respect to this reference, the fusion cross sections for the proton-rich systems show an enhancement likely related to static effects. An excitation function for the respective total-reaction cross section was extracted from the measured elastic data along with additional data from the literature. Surprisingly, this excitation function follows the trend expected for weakly bound systems
TourGuide: Augmented Reality Based on Structure Recognition
Get PDFTourGuide is software for Android phones and tablets that allows users to use augmented reality to see the world. TourGuide uses realtime video to search for images that match those in its database. When these images are found, TourGuide overlays the image with a number of options – from URLs/Web to video viewing – that are used to access more information about the image by touching the screen.
The software is designed so that configuring it is easy. In addition to the viewer, there is also a TourGuide Editor that allows configuration on a tablet or phone
Alfred Dreyfus: Traître ou Victime?
No full textIn the late 19th century, false accusations of treason leveled against Captain Alfred Dreyfus launched France into a twelve-year struggle against anti-Semitism. Dreyfus, a Jew, was accused of passing valuable information regarding French military initiatives to the German Army. Despite the lack of concrete evidence, he was arrested and condemned in 1894, stripped of his rank, and exiled from his country. Finally, in 1906, he was officially pardoned and his honor restored. The affair deeply divided France. Some believed Dreyfus had truly committed a crime and received the punishments he deserved. Others harbored suspicions that it was a case of religious persecution, since many of his accusers were known for their anti-Semitic beliefs. As this research shows, this debate of motives is still being investigated today. Furthermore, the research examines not only the affair itself, but also the repercussions the event holds for the modern world. It demonstrates, in addition to questions of religious liberty, the tendencies for those in authority to abuse their power, an issue that continues to plague our governments to this day
The Inadequacy of AP English Literature and Composition Exams as Substitutes for College Writing Courses
No full textWhile the College Board promotes the benefits of taking Advanced Placement (AP) exams, it neglects to inform students that the AP English Literature and Composition exam does not reflect a typical college writing class assessment. The goal of this research project is to demonstrate the need for student enrollment in a college writing course and the consequences of exemption after passing the AP English Literature and Composition Exam. Even if students pass the AP test, they likely have not fully mastered writing skills that would warrant an exemption from a college writing class. Unfortunately, college students are usually required to take only one college writing course, which can be substituted with AP credit. After analyzing studies conducted by the College Board and other institutions, it is obvious that students who take more writing courses will have better writing skills. I argue that all college students, regardless of their intended major, should take two college writing courses and that only one of these courses may be substituted with an AP English Literature and Composition Exam score of 4 or 5. The second writing course will be departmentally oriented and give students the opportunity to improve their writing skills in the discipline they are pursuing. By taking an additional writing course, students will improve their writing skills and be more fully prepared for further academic and occupational tasks