The use of thin films as solid lubricating makes it an excellent option for controlling wear and friction under certain operating conditions, in addition to not harming the environment. Thus, this work aims to study plasma deposition with a cathodic cage of MoS2 thin films on AISI 1020 steel substrates. From the adaptation of the cathode Cage named cathode cylinders, the samples were treated in cathodic and floating potential with temperatures of 300 °C, 350 °C, and 400 °C in an argon atmosphere. After the treatments, they were subjected to chemical analysis by X-ray diffraction (XRD) and Raman spectroscopy, in addition to a calotest tribological test. Also, it was possible to quantify the coating thickness using scanning electron microscopy (SEM). In general, the results indicated success in the deposition of molybdenum disulfide in all samples treated at fluctuating potential, as it is possible to visualize in the XRD since it indicated the presence of peaks referring to MoS2 and its compounds, in addition to an expressive reduction in wear through the calotest test.

Topological excitations are believed to play an important role in different areas of physics. For example, one case of topical interest is the use of dual models of quantum cromodynamics to understand properties of the vacuum and confinement through the condensation of magnetic monopoles and vortices. Other applications are related to the role of these topological excitations, nonhomogeneous solutions of the field equations, in phase transitions associated to spontaneous symmetry breaking in gauge theories, whose study is of importance, for instance, in phase transitions in the early universe. Here we show a derivation of a model dual to the scalar Abelian Higgs model where its topological excitations, namely vortex-strings, become manifest and can be treated in a quantum field theory way. The derivation of the nontrivial contribution of these vacuum excitations to phase transitions and its analogy with superconductivity is then made possible and they are studied here.

Relatamos a experiência de utilizar programação em Maple como ferramenta de aprendizagem do estudante num curso básico de teoria eletromagnética. Acreditamos que este relato possa ser útil a quem desejar utilizar o computador como instrumento pedagógico no ensino de Física.

We describe an experience in using programming in Maple as a student's tool for the learning of introductory electromagnetic theory. We believe that this paper can be of use for those interested in using computers as a pedagogical tool.