Isotopic effects on the thermal conductivity of graphene nanoribbons: localization mechanism

Thermal conductivity of graphene nanoribbons (GNR) with length 106~{\AA} and width 4.92~{\AA} after isotopic doping is investigated by molecular dynamics with quantum correction. Two interesting phenomena are found: (1) isotopic doping reduces thermal conductivity effectively in low doping region, and the reduction slows down in high doping region; (2) thermal conductivity increases with increasing temperature in both pure and doped GNR; but the increasing behavior is much more slowly in the doped GNR than that in pure ones. Further studies reveal that the physics of these two phenomena is related to the localized phonon modes, whose number increases quickly (slowly) with increasing isotopic doping in low (high) isotopic doping region.Comment: 6 fig

Capturing doping attitudes by self-report declarations and implicit assessment: a methodology study

BACKGROUND: Understanding athletes' attitudes and behavioural intentions towards performance enhancement is critical to informing anti-doping intervention strategies. Capturing the complexity of these attitudes beyond verbal declarations requires indirect methods. This pilot study was aimed at developing and validating a method to assess implicit doping attitudes using an Implicit Associations Test (IAT) approach. METHODS: The conventional IAT evaluation task (categorising 'good' and 'bad' words) was combined with a novel 'doping' versus 'nutrition supplements' category pair to create a performance-enhancement related IAT protocol (PE-IAT). The difference between average response times to 'good-doping' and 'bad-doping' combinations represents an estimate of implicit attitude towards doping in relation to nutritional supplements. 111 sports and exercise science undergraduates completed the PE-IAT, the Performance Enhancement Attitude Scale (PEAS) and answered questions regarding their beliefs about doping. RESULTS: Longer response times were observed in the mixed category discrimination trials where categories 'good' and 'doping' shared the same response key (compared to 'bad-doping' combination on the same key) indicating a less favourable evaluation of doping substances. The PE-IAT measure did not correlate significantly with the declared doping attitudes (r = .181, p = .142), indicating a predictable partial dissociation. Action-oriented self-report expressed stronger associations with PE-IAT: participants who declared they would consider using doping showed significantly less implicit negativity towards banned substances (U = 109.00, p = .047). Similarly, those who reported more lenient explicit attitudes towards doping or expressly supported legalizing it, showed less implicit negativity towards doping in the sample, although neither observed differences reached statistical significance (t = 1.300, p = .198, and U = 231.00, p = .319, respectively). Known-group validation strategy yielded mixed results: while competitive sport participants scored significantly lower than non-competitive ones on the PEAS (t = -2.71, p = .008), the two groups did not differ on PE-IAT (t = -.093, p = .926). CONCLUSION: The results suggest a potential of the PE-IAT method to capture undeclared attitudes to doping and predict behaviour, which can support targeted anti-doping intervention and related research. The initial evidence of validity is promising but also indicates a need for improvement to the protocol and stimulus material

Covalent Nitrogen Doping and Compressive Strain in MoS2 by Remote N2 Plasma Exposure

Controllable doping of two-dimensional materials is highly desired for ideal device performance in both hetero- and p-n homo-junctions. Herein, we propose an effective strategy for doping of MoS2 with nitrogen through a remote N2 plasma surface treatment. By monitoring the surface chemistry of MoS2 upon N2 plasma exposure using in-situ X-ray photoelectron spectroscopy, we identified the presence of covalently bonded nitrogen in MoS2, where substitution of the chalcogen sulfur by nitrogen is determined as the doping mechanism. Furthermore, the electrical characterization demonstrates that p-type doping of MoS2 is achieved by nitrogen doping, in agreement with theoretical predictions. Notably, we found that the presence of nitrogen can induce compressive strain in the MoS2 structure, which represents the first evidence of strain induced by substitutional doping in a transition metal dichalcogenide material. Finally, our first principle calculations support the experimental demonstration of such strain, and a correlation between nitrogen doping concentration and compressive strain in MoS2 is elucidated

Reporting doping in sport: national level athletes' perceptions of their role in doping prevention.

This paper qualitatively explores national level athletes' willingness to report doping in sport. Following ethical approval, semi-structured interviews were conducted with nine national level athletes from rugby league (n = 5) and track and field athletics (n = 4). Thematic analysis established the main themes within the data. Contextual differences existed around the role that athletes perceived they would play if they became aware of doping. Specifically, track and field athletes would adopt the role of a whistle-blower and report individuals who were doping in their sport. In comparison, the rugby league players highlighted a moral dilemma. Despite disagreeing with their teammates' actions, the players would adhere to a code of silence and refrain from reporting doping. Taking these findings into account, prevention programs might focus on changing broader group and community norms around doping. In doing so, community members' receptivity to prevention messages may increase. Moreover, developing skills to intervene (e.g., speaking out against social norms that support doping behavior) or increasing awareness of reporting lines could enhance community responsibility for doping prevention. In sum, the findings highlight the need to consider the context of sport and emphasize that a one-size-fits-all approach to anti-doping is problematic

Doping

Since centuries ago, man has always tried to find ways to improve human performance whilst suffering less in doing so. People who were thought to be the best were preferentially fed better diets and given treatments that were considered to be beneficial to their performance.peer-reviewe

Intraplanar couplings in the CuO_2 lattice of cuprate superconductors

We have investigated the doping dependencies of the basal areas in single-layer high-T_c cuprates La_{2-x}Sr_xCuO_4 and HgBa_2CuO_x, as well as in two-layer Y_{1-y}Ca_yBa_2Cu_3O_x and HgBa_2CaCu_2O_x. The basal areas not only tend to shrink on hole doping, as expected from single electron quantum chemistry, but exhibit also a "bulge'' around optimum doping. We attribute the "bulge'' to the effects of the strongly correlated quantum liquid on the CuO_2 lattice, rendering it nearly incompressible around optimum doping, but highly compressible in the weakly overdoped regime. Inhomogenous doping cannot account for this anomaly in the electronic compressibility of the CuO_2 lattice.Comment: 2 pages, 2 figures, to appear in Physica C (Proc. M2S-HTSC-VII

Superconducting Mechanism through direct and redox layer doping in Pnictides

The mechanism of superconductivity in pnictides is discussed through direct doping in superconducting FeAs and also in charge reservoir REO layers. The un-doped SmFeAsO is charge neutral SDW (Spin Density Wave) compound with magnetic ordering below 150 K. The Superconducting FeAs layers are doped with Co and Ni at Fe site, whereas REO layers are doped with F at O site. The electron doping in SmFeAsO through Co results in superconductivity with transition temperature (Tc) maximum up to 15 K, whereas F doping results in Tc upto 47 K in SmFeAsO. All these REFe/Co/NiAsO/F compounds are iso-structural to ZrCuSiAs structure. The samples are crystallized in a tetragonal structure with space group P4/nmm. Variation of Tc with different doping routes shows the versatility of the structure and mechanism of occurrence of superconductivity. It seems doping in redox layer is more effective than direct doping in superconducting FeAs layer.Comment: 4 Pages text + Figs: ([email protected]