The Structure of Graphene on Graphene/C60/Cu Interfaces: A Molecular Dynamics Study

Two experimental studies reported the spontaneous formation of amorphous and crystalline structures of C60 intercalated between graphene and a substrate. They observed interesting phenomena ranging from reaction between C60 molecules under graphene to graphene sagging between the molecules and control of strain in graphene. Motivated by these works, we performed fully atomistic reactive molecular dynamics simulations to study the formation and thermal stability of graphene wrinkles as well as graphene attachment to and detachment from the substrate when graphene is laid over a previously distributed array of C60 molecules on a copper substrate at different values of temperature. As graphene compresses the C60 molecules against the substrate, and graphene attachment to the substrate between C60s ("C60s" stands for plural of C60) depends on the height of graphene wrinkles, configurations with both frozen and non-frozen C60s structures were investigated in order to verify the experimental result of stable sagged graphene when the distance between C60s is about 4 nm and height of graphene wrinkles is about 0.8 nm. Below the distance of 4 nm between C60s, graphene becomes locally suspended and less strained. We show that this happens when C60s are allowed to deform under the compressive action of graphene. If we keep the C60s frozen, spontaneous "blanketing" of graphene happens only when the distance between them are equal or above 7 nm. Both above results for the existence of stable sagged graphene for C60 distances of 4 or 7 nm are shown to agree with a mechanical model relating the rigidity of graphene to the energy of graphene-substrate adhesion. In particular, this study might help the development of 2D confined nanoreactors that are considered in literature to be the next advanced step on chemical reactions.Comment: 7 pages, 4 figure

Idiosyncratic psychological aspects in entrepreneurship

Entrepreneurship is having the courage to transform an idea in reality and with it achieve personal, nancial and recognition satisfaction. The psychological ability to handle failure has proven essential in success. We analysed the importance of idiosyncratic psychological aspects in the success of entrepreneurs through an observational study accompanying 20 entrepreneurs from the idea presentation phase to company incorporation. During the observation period 4 distinct psychological phases of the entrepreneurs were observed, being it possible to describe them as follows: absorption of information and knowledge; application of the gathered knowledge to their speci c cases; frustration generated by criticism, namely from investors who didn’t recognise the value of their projects; realism and implementation of the project. Having passed more than 6 months after the analysis period, one can verify that the entrepreneurs who have travelled the 4 phases are today developing their projects being that the remaining ones are in a similar situation as at the end of the initial two months. Conclusion: The ability to cope with frustration and rejection is a determinant factor in the success of the entrepreneur. The ability to learn from rejection, more than resilience help the entrepreneur to proceed

Effects of environmental temperature on the corn stunt spiroplasma disease.

Suplemento. Edição dos Abstracts do 10º International Congress of Plant Pathology, Beijing, 2013

Vascular grassland plants of Tibagi River Spring, Ponta Grossa, Brazil.

A systematic survey was carried out on wet grasslands found over Histosols at Upper Tibagi River basin, between Ponta Grossa and Palmeira municipalities, in the state of Paraná, Brazil, place of high importance because of soil water retention capability and soil carbon pool composition. We provide a checklist containing 146 species, 96 genera and 42 plant families for the area. Families with higher species richness were Asteraceae (27 species; 21 genera), Poaceae (24; 16) and Cyperaceae (18; 6). Four species were classified as endangered or rare, and one as exotic. The specific richness in wet grassland environments at the state of Paraná underlines the need for conservation efforts encompassing these formations

Electric field inversion asymmetry: Rashba and Stark effects for holes in resonant tunneling devices

We report experimental evidence of excitonic spin-splitting, in addition to the conventional Zeeman effect, produced by a combination of the Rashba spin-orbit interaction, Stark shift and charge screening. The electric-field-induced modulation of the spin-splitting are studied during the charging and discharging processes of p-type GaAs/AlAs double barrier resonant tunneling diodes (RTD) under applied bias and magnetic field. The abrupt changes in the photoluminescence, with the applied bias, provide information of the charge accumulation effects on the device.Comment: 4 pages, 2 figure

Classicality in discrete Wigner functions

Gibbons et al. [Phys. Rev. A 70, 062101(2004)] have recently defined a class of discrete Wigner functions W to represent quantum states in a Hilbert space with finite dimension. We show that the only pure states having non-negative W for all such functions are stabilizer states, as conjectured by one of us [Phys. Rev. A 71, 042302 (2005)]. We also show that the unitaries preserving non-negativity of W for all definitions of W form a subgroup of the Clifford group. This means pure states with non-negative W and their associated unitary dynamics are classical in the sense of admitting an efficient classical simulation scheme using the stabilizer formalism.Comment: 10 pages, 1 figur

Use of passive samplers to detect Organochlorine Pesticides in air and water at Wetland Mountain region sites (S-SE Brazil)

Low-density polyethylene (LDPE) passive samplers were deployed in upland surface waters and the overlying atmosphere during May and June 2012, to determine the transport and trends of freely dissolved and gaseous organochlorine pesticides (OCPs) along altitudinal gradients in mountain regions in south and southeast Brazil. Gaseous OCP concentrations were dominated by hexachlorobenzene (3.0 to 29 pg.m-3) and endosulfans (Ʃ= α-endosulfan + β-endosulfan + endosulfan sulphate, 170 to 260 pg.m-3), whereas freely dissolved endosulfans were significantly higher than all other OCPs (p \u3c 0.001). The presence of some target pesticides at the highest elevation sites indicated their efficient high-altitude transport from regional sources. Air-water exchange gradients indicated net deposition of most volatile and recently banned OCPs (e.g., HCB, endosulfan) over Brazilian mountains. Moreover, the exposure of these sites to large-scale continental airflows with varying source contributions may partly explain the atmospheric deposition of selected OCPs over upland freshwaters at tropical and subtropical mountains sites in Brazil. These findings, couple with LDPE passive air and water sampling measurements, point out the potential inputs from distant sources of semi-volatile chemicals to the two high-altitude sites