4,770 research outputs found

    Towards electron transport measurements in chemically modified graphene: The effect of a solvent

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    Chemical functionalization of graphene modifies the local electron density of the carbon atoms and hence electron transport. Measuring these changes allows for a closer understanding of the chemical interaction and the influence of functionalization on the graphene lattice. However, not only chemistry, in this case diazonium chemistry, has an effect on the electron transport. Latter is also influenced by defects and dopants resulting from different processing steps. Here, we show that solvents used in the chemical reaction process change the transport properties. In more detail, the investigated combination of isopropanol and heating treatment reduces the doping concentration and significantly increases the mobility of graphene. Furthermore, the isopropanol treatment alone increases the concentration of dopants and introduces an asymmetry between electron and hole transport which might be difficult to distinguish from the effect of functionalization. The results shown in this work demand a closer look on the influence of solvents used for chemical modification in order to understand their influence

    Scholarly communications program: force for change

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    The changing landscape of scholarly publication and increasing journal costs have resulted in a need for proactive behavior in libraries. At Johns Hopkins University in Baltimore, Maryland, a group of librarians joined forces to bring these issues to the attention of faculty and to begin a dialog leading to change. This commentary describes a comprehensive program undertaken to raise faculty awareness of scholarly communications issues. In addition to raising faculty interest in the issues at hand, the endeavor also highlights an area where library liaisons can increase their communication with the units they serve

    Surviving suppression : no detectable impacts of Class A foam on soil invertebrates and some Australian native plants

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    Firefighting foams (Class A foams) are an effective and widespread firefighting tool which are frequently used in environmentally sensitive areas. Firefighting foams are known to be ecologically damaging in aquatic environments, however their impacts at the plant species or ecosystem level are relatively unknown. Reports of shoot damage to plants, suppressed flowering, and changes in plant community composition suggested that the ecological damage caused by their use may be unacceptable. However, applications of foam to seedlings of some Australian plant species from representative and widespread families, showed no detectable impacts on a range of vegetative growth characteristics. Application of 1.0% foam to heathland soils showed no detectable impacts on soil invertebrate Orders sampled over several months. The results are encouraging for the continued use of Class A foam as a fire suppression technique.<br /

    Ultrafast spatio-temporal dynamics of terahertz generation by ionizing two-color femtosecond pulses in gases

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    We present a combined theoretical and experimental study of spatio-temporal propagation effects in terahertz (THz) generation in gases using two-color ionizing laser pulses. The observed strong broadening of the THz spectra with increasing gas pressure reveals the prominent role of spatio-temporal reshaping and of a plasma-induced blue-shift of the pump pulses in the generation process. Results obtained from (3+1)-dimensional simulations are in good agreement with experimental findings and clarify the mechanisms responsible for THz emission

    Popular support for military intervention and anti-establishment alternatives in Tunisia: Appraising outsider eclecticism

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    Popular attitudes in support of authoritarian alternatives and weak party systems constitute important threats to democratic consolidation and the stability of new democracies. This article explores popular alienation from established political actors in Tunisia. Under what conditions do citizens support alternatives to the elites in power and the institutional infrastructure of a new democracy? Drawing on an original, nationally representative survey in Tunisia administered in 2017, this article examines three categories of popular attitudes in support of political outsiders.Military interventionism&nbsp;appears in people’s preferences for anti-system politics—the most immediate challenge to the country’s stability and democratic transition.&nbsp;Anti-political establishment&nbsp;sentiments are shown in people’s preferences for an enhanced role of the country’s main trade union as a civil-society alternative to political party elites. Finally,&nbsp;outsider eclecticism&nbsp;is the seemingly incoherent phenomenon of concurrent support for a civil society actor and the military as an ‘authoritarian alternative.’ Anti-establishment sentiments will continue to be an important element in Tunisian post-authoritarian politics, evidenced by the rise to power of Kais Said in the 2019 presidential elections and his 2021 decision to dismiss parliament. In turn, popular support for military intervention may have implications for the country’s domestic security and peaceful transition

    The s-process branching at 185W

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    The neutron capture cross section of the unstable nucleus 185W has been derived from experimental photoactivation data of the inverse reaction 186W(gamma,n)185W. The new result of sigma = (687 +- 110) mbarn confirms the theoretically predicted neutron capture cross section of 185W of sigma = 700 mbarn at kT = 30 keV. A neutron density in the classical s-process of n_n = (3.8 +0.9 -0.8} * 1e8 cm-3 is derived from the new data for the 185W branching. In a stellar s-process model one finds a significant overproduction of the residual s-only nucleus 186Os.Comment: ApJ, in pres

    Retrospective analysis and clinical evaluation of mandible reconstruction with free fibula flap

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    The objective of this investigation was to evaluate the indications for and the functional and cosmetic results of mandible reconstruction using free vascularized fibular flaps. It was also designed to assess the patients' quality of life, daily activities, and self-esteem, with special emphasis on patient satisfaction. We conducted a retrospective chart review of all patients who underwent osseus or osteocutaneous free flap reconstruction of the mandible over a 10-year period (1992-2002). Those in whom a vascularized fibular flap was used were included in the study and invited for a follow-up comprehensive physical examination and x-ray evaluation. A questionnaire was also administered to evaluate patient satisfaction. Twenty-six patients were included in the study. Fourteen patients died after an average of 2years and 9months postoperatively due to their prognosis despite surgical intervention and adjuvant therapy. Of the remaining 12 patients, 6 appeared for the follow-up evaluation, 2 were unavailable for follow-up, and 4 denied participating. Of these 6 patients, all experienced a decrease in pain and were satisfied with their results. At the time of the latest follow-up, they experienced some difficulties swallowing, and in 3 patients, their articulation was impaired. All 6 patients would undergo the procedure again. Reconstruction of the mandible using a vascularized fibular graft produces satisfactory functional and cosmetic results. In benign lesions, the procedure is highly indicated. However, in the case of malignancy, most patients do not survive their primary tumor. Given the patients limited life expectancy, the improvement in their quality of life as a result of the improved appearance and function of the reconstructed mandible needs to be weighed against the potential morbidity of the operative intervention on an individual basi

    Tim54p connects inner membrane assembly and proteolytic pathways in the mitochondrion

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    Tim54p, a component of the inner membrane TIM22 complex, does not directly mediate the import of inner membrane substrates but is required for assembly/stability of the 300-kD TIM22 complex. In addition, Δtim54 yeast exhibit a petite-negative phenotype (also observed in yeast harboring mutations in the F1Fo ATPase, the ADP/ATP carrier, mitochondrial morphology components, or the i–AAA protease, Yme1p). Interestingly, other import mutants in our strain background are not petite-negative. We report that Tim54p is not involved in maintenance of mitochondrial DNA or mitochondrial morphology. Rather, Tim54p mediates assembly of an active Yme1p complex, after Yme1p is imported via the TIM23 pathway. Defective Yme1p assembly is likely the major contributing factor for the petite-negativity in strains lacking functional Tim54p. Thus, Tim54p has two independent functions: scaffolding/stability for the TIM22 membrane complex and assembly of Yme1p into a proteolytically active complex. As such, Tim54p links protein import, assembly, and turnover pathways in the mitochondrion
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