ABSTRACT
The gallium-68 radiolabelling of new functional graphene oxide composites is reported herein along with kinetic stability investigations of the radio-nanohybrids under different environments and insights into their surface characteristics by SEM and XPS. The present work highlights the potential of graphene oxides as nanocarriers for small molecules such as bis(thiosemicarbazonato) complexes to act as multifunctional platforms for rapid and effective radioimaging agent incorporation.
ABSTRACT
We performed Monte Carlo simulations of a bilayer system composed of two thin films, one ferromagnetic (FM) and the other antiferromagnetic (AFM). Two lattice structures for the films were considered: simple cubic and body centered cubic (bcc). We imposed an uncompensated interfacial spin structure in both lattice structures; in particular we emulated an FeF2-FM system in the case of the bcc lattice. Our analysis focused on the incidence of the interfacial strength interactions between the films, J(eb), and the effect of thermal fluctuations on the bias field, H(EB). We first performed Monte Carlo simulations on a microscopic model based on classical Heisenberg spin variables. To analyze the simulation results we also introduced a simplified model that assumes coherent rotation of spins located on the same layer parallel to the interface. We found that, depending on the AFM film anisotropy to exchange ratio, the bias field is controlled either by the intrinsic pinning of a domain wall parallel to the interface or by the stability of the first AFM layer (quasi-domain wall) near the interface.
ABSTRACT
We introduce a model for granular flow in a one-dimensional rice pile that incorporates rolling effects through a long-range rolling probability for the individual rice grains proportional to r(-rho), r being the distance traveled by a grain in a single toppling event. The exponent rho controls the average rolling distance. We have shown that the crossover from the power law to the stretched exponential behaviors observed experimentally in the granular dynamics of rice piles can be well described as a long-range effect resulting from a change in the transport properties of individual grains. We showed that stretched exponential avalanche distributions can be associated with a long-range regime for 1
ABSTRACT
We analyze the equilibrium properties of a chain of ferromagnetically coupled rotators which interact through a force that decays as r(-alpha) where r is the interparticle distance and alpha>/=0. By integrating the equations of motion we obtain the microcanonical time averages of both the magnetization and the kinetic energy. We detect three different regimes depending on whether alpha belongs to the intervals [0,1), (1,2), or (2,infinity). For 0
ABSTRACT
A Tsallis-statistics-based generalization of the gradient descent dynamics (using non- extensive cost functions), recently introduced by one of us, is proposed as a learning rule in a simple perceptron. The resulting Langevin equations are solved numerically for different values of an index q (q = 1 and q ≠ 1 respectively correspond to the extensive and non-extensive cases) and for different cost functions. The results are compared with the learning curve (mean error versus time) obtained from a learning experiment carried out with human beings, showing an excellent agreement for values of q slightly above unity. This fact illustrates the possible importance of including some degree of non-locality (non-extensivity) in computational learning procedures, whenever one wants to mimic human behaviour.
