113,723 research outputs found
Radiation detection properties of 4H-SiC Schottky diodes irradiated up to 10(16) n/cm(2) by 1 MeV neutrons
No full textWe report the results of an experimental study on the radiation hardness of 4H-SiC diodes used as alpha-particle detectors with 1 MeV neutrons up to a fluence of 8 x 10(15) n/cm(2). As the irradiation level approaches the range 10(15) n/cm(2), the material behaves as intrinsic due to a very high compensation effect and the diodes are still able to detect with a reasonable good Charge Collection Efficiency (CCE = 80%).For fluences > 10(15) n/cm(2) CCE decreases monotonically to approximate to 20 % at the highest fluence. Heavily irradiated SiC diodes have been studied, by means of Photo Induced Current Transien
Deep Levels in 4H Silicon Carbide Epilayers Induced by Neutron-Irradiation up to 1016 n/cm2
No full textauthor-bios-SRD-19-0063.R1 – Supplemental material for The Network Structure of Police Misconduct
No full textSupplemental material, author-bios-SRD-19-0063.R1 for The Network Structure of Police Misconduct by George Wood, Daria Roithmayr and Andrew V. Papachristos in Socius</p
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Neutron irradiation effects on standard and oxygenated silicon diodes
No full textSilicon diodes processed on standard and oxygenated silicon substrates by two different manufacturers have been irradiated by neutrons in a nuclear reactor and by the 9Be(d,n)10B nuclear reaction. The leakage current density (JD) increase is linear with the neutron fluence. JD and its annealing curve at 80°C do not present any sizeable dependence on substrate oxygenation and/or manufacturing process. On the contrary, standard devices from one manufacturer present the lowest acceptor introduction rate (β) for the effective substrate doping concentration (Neff), showing that the β dependence on the particular process can be important, overtaking the small substrate oxygenation effect. Finally, the average saturation value of the Neff reverse annealing is slightly lower for the oxygenated samples, pointing out a positive effect of the substrate oxygenation even for devices irradiated by neutrons
Thermodynamic and MD studies of anion complexation by cyclopentaleucine in acetonitrile and dimethyl sulfoxide
No full textComplexation affinity of cyclic pentaleucine for halogen anions, thiocyanate and oxoanions was studied in acetonitrile and dimethyl sulfoxide. Equilibrium constants and derived Gibbs energies, as well as enthalpies and entropies of the corresponding reactions were determined by means of microcalorimetric and H-1 NMR titrations. To get more detailed insight into the binding of anions by the cyclopeptide, classical molecular dynamics simulations were carried out. The preorganization of cyclopentaleucine binding site by inclusion of solvent molecules was observed in acetonitrile by these simulations. The investigated receptor showed larger affinity for all anions in acetonitrile than in dimethyl sulfoxide. The results of H-1 NMR studies and those of molecular dynamics simulations indicated that the bound anions were coordinated by the amide groups of cyclopeptide. The stoichiometry of most of the complexes was 1:1 (receptor:anion), with the exception of dihydrogen phosphate and hydrogen sulfate complexes, where higher stoichiometries (1:2 and 2:1, respectively) were also observed. In the case of complexes with H2PO4- anion, in both acetonitrile and dimethyl sulfoxide the binding of dihydrogen phosphate dimer was observed, whereas the species in which two ligands coordinate one HSO4- ion was observed in acetonitrile. The obtained thermodynamic reaction parameters and the observed rather strong solvent effect on the studied equilibria were discussed regarding anions and receptor structural properties as well as solvation abilities of the solvents used
Chloride-Assisted Peptide Macrocyclization
No full textThe role of the Cl− anion as a templating agent for the synthesis of cyclopeptides was assessed through the preparation of three new homocyclolysines and other six cyclic peptides by head-to-tail lactamization. Isolated yields of products obtained by chloride-templating approach were considerably higher than those gained by a cation-promoted procedure, whereby, in some cases, only the anion-assisted synthesis yielded the desired cyclopeptides
Metal-ion-assisted synthesis of cyclic homopeptides
No full textIn the recent years cyclic peptides have attracted attention since they find applications in many fields from drug discovery to nanomaterials. These compounds have been difficult to prepare due to the fact that the activated peptide must adopt an entropically disfavoured conformation before forming the desired product[1]. The most important factor for successful peptide macrocyclization is ring size. Peptides that contain less than seven aminoacids are troublesome to cyclize[2]. In this work we will describe synthesis of small homocyclopeptides containig 4-6aminoacids.
Cyclic peptides are also known as versatile ion-binders[3] but their binding affinities are often reduced by the inadequate orientation of amide functional group. To overcome these problems, cyclopeptides will be conjugated to a molecules with rigid geometry, such as calixarenes. Homocyclolysine and homocycloserine will be bind, , to calixarenes exploiting functional groups via amide bond on peptide's side chain. Influence of lenght of side chains on affinities of this conjugates towards different anions will be investigated.
Linear precursors were sinthesized using standard solution phase peptide synthesis and HOBt, HBTU as a coupling reagents. A three-dimensional orthogonal protection scheme was required to built the linear peptides, to deprotect the N- and C-termini and to cyclize them in a head-to-tail fashion. To promote the cyclization,different alkali metal ions were used depending on a the size of the desired cyclic peptide. These ions coordinate amidic oxygen atoms along the chain forcing the linear peptide to form a strong turn structure and to bring the N- and C-termini closer, allowing helping in that way cyclization to occur
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