3,807 research outputs found

    Variable and reversible quantum structures on a single carbon nanotube

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    The band gap of a semiconducting single wall carbon nanotube decreases and eventually vanishes leading to metalization as a result of increasing radial deformation. This sets in a band offset between the undeformed and deformed regions of a single nanotube. Based on the superlattice calculations, we show that these features can be exploited to realize various quantum well structures on a single nanotube with variable and reversible electronic properties. These quantum structures and nanodevices incorporate mechanics and electronics.Comment: 7 pages, 4 figures, To be appear in PR

    Collisional Damping of Giant Monopole and Quadrupole Resonances

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    Collisional damping widths of giant monopole and quadrupole excitations for 120^{120}Sn and 208^{208}Pb at zero and finite temperatures are calculated within Thomas-Fermi approximation by employing the microscopic in-medium cross-sections of Li and Machleidt and the phenomenological Skyrme and Gogny forces, and are compared with each other. The results for the collisional widths of giant monopole and quadrupole vibrations at zero temperature as a function of the mass number show that the collisional damping of giant monopole vibrations accounts for about 30-40% of the observed widths at zero temperature, while for giant quadrupole vibrations it accounts for only 20-30% of the observed widths of zero temperature.Comment: RevTex, 12 pages, 6 PS figure

    The effect of feeding frequency on growth performance and body composition in juvenile rainbow trout (Oncorhynchus mykiss) reared in cold seawater

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    This study was done to investigate the effects of different feeding frequencies on the growth, feed efficiency and specific growth rate (%) of juvenile of rainbow trout (Oncorhynchus mykiss, weight 16.44±0.22 g) rearing in cold sea water conditions (5.8 to 9.3°C; 17 to 18 ppt). Fish were fed on a commercial feed to the apparent satiation twice a day (Control), six times every day (TD6), four times every day (TD4) and three times every day (TD3) for 8 weeks of the trial. The fish fed to satiation in all the experimental groups. Weight gain, growth rate, feed intake and final body weight decreased with reduction of feeding frequency from six times daily to two times daily. The fish fed at TD6 had relatively high apparent net protein retention and better feed conversion efficiency compared with the fish fed at the control, TD4 and TD3. The feeding frequency had significant effect on the crude lipid, crude protein but not moisture and crude ash proximate composition of rainbow trout. It was recommended that six meals per day was the optimal feeding frequency for juvenile rainbow trout reared in cold sea water at 5.8 to 9.3°C, 17 to 18 ppt.Key words: Feeding frequencies, growth, body composition, sea water, Oncorhynchus mykiss

    Metal nanoring and tube formation on carbon nanotubes

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    The structural and electronic properties of aluminum covered single wall carbon nanotubes (SWNT) are studied from first-principles for a large number of coverage. Aluminum-aluminum interaction that is stronger than aluminum-tube interaction, prevents uniform metal coverage, and hence gives rise to the clustering. However, a stable aluminum ring and aluminum nanotube with well defined patterns can also form around the semiconducting SWNT and lead to metallization. The persistent current in the Al nanoring is discussed to show that a high magnetic field can be induced at the center of SWNT.Comment: Submitted to Physical Review

    A Recombinant PvpA Protein-Based Diagnostic Prototype for Rapid Screening of Chicken Mycoplasma gallisepticum infections

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    Cataloged from PDF version of article.Mycoplasma gallisepticum is the primary agent of chronic respiratory disease causing important economic losses in the poultry industry. Serological monitoring is essential to maintain mycoplasma-free breeder flocks and often complicated by the cross-reactions between different mycoplasma species. To overcome serological cross-reactions, a large fragment of the M. gallisepticum PvpA cytadhesin, species-specific surface-exposed protein, was produced in E. coli as a recombinant protein (rPvpA336) and used as a potential diagnostic antigen. The rPvpA336 protein possesses 336 mycoplasma-specific amino acids with relative molecular weight of 44 kDa. A deletion region of 37 amino acids was identified when compared to the wild-type PvpA protein. Immunoreactivity of the rPvpA336 protein has been demonstrated by Western blot analysis with M. gallisepticum-positive and -negative chicken sera. Furthermore, an enzymatic rapid immunofiltration assay (ERIFA) prototype based on the rPvpA336 protein has been developed and its species-specific detection capability has been demonstrated by using M. gallisepticum and/or M. synoviae-positive and -negative chicken sera. In addition to its species-specificity, the ERIFA prototype presents certain advantages such as rapidity, field-applicability and cost-effectiveness. Therefore, these advantages would make the prototype a species-specific rapid diagnostic tool of choice in the field and limited laboratory conditions for screening M. gallisepticum infections. © 2007 Elsevier B.V. All rights reserved

    The effect of orthodontic extraoral appliances on depression and the anxiety levels of patients and parents

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    Background: Psychosocial consequences and post‑operative anxiety in patients after fixed orthodontic treatment are important parameters that must be evaluated by clinicians not to effect patient and their parent’s psychosocial mood negatively.Objective: The aim of this study was to evaluate the changes in depression and anxiety levels of orthodontic patients and their parents before the extraoral appliance therapy, and at a 1‑year follow‑up.Materials and Methods: Patients and one of their parents responded to a series of questionnaires and evaluation scales in order to assess depression and anxiety levels. Two groups of patients and their parents were surveyed; one group that had not yet embarked on the treatment and another that had commenced extra‑oral appliance therapy 1 year prior to the study.Results: The 1‑year‑treatment group scored significantly higher than the pre‑treatment group on the depression scale and the trait‑anxiety scale. State‑trait anxiety inventory scores did not differ significantly between the  groups. The parents of the 1‑year‑treatment group also scored significantly higher on the Beck depression inventory than those of the pre‑treatment group.Conclusion: The results of this study emphasize the need for due consideration of psychological parameters before and during treatment with extra‑oral appliances, particularly with regard to depression and anxiety.Key words: Anxiety, depression, exoral appliance
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