Flexible magnetic membranes based on bacterial cellulose and its evaluation as electromagnetic interference shielding material

Flexible magnetic membranes with high proportion of magnetite were successfully prepared by previous impregnation of the never dried bacterial cellulose pellicles with ferric chloride followed by reduction with sodium bisulfite and alkaline treatment for magnetite precipitation. Membranes were characterized by Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), vibrating magnetometer, field emission scanning electron microscopy (FEG-SEM) and impedance spectroscopy. Microwave properties of these membranes were investigated in the X-band (8.2 to 12.4 GHz). FEG-SEM micrographs show an effective coverage of the BC nanofibers by Fe 3O4 nanoparticles. Membranes with up to 75% in weight of particles have been prepared after 60 min of reaction. Magnetite nanoparticles in the form of aggregates well adhered to the BC fibers were observed by SEM. The average crystal sizes of the magnetic particles were in the range of 10 ± 1 to 13 ± 1 nm (estimated by XRD). The magnetic particles in the BC pellicles presented superparamagnetic behavior with a saturation magnetization in the range of 60 emu g- 1 and coercive force around 15 Oe. These magnetic pellicles also displayed high electrical permittivity and a potential application as microwave absorber materials. © 2013 Elsevier B.V.

Análise e implementação de técnicas de medição de microvibrações utilizando interferometria óptica e processadores digitais de sinais

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

O modelo de injeção de potência do TCSC e sua aplicação no estudo da estabilidade a pequenas perturbações

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Modelagem numérica do escoamento em válvulas automáticas de compressores pelo Método da Fronteira Imersa

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Desenvolvimento e caracterização de dispositivos de visualização eletroluminescentes

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

El modelo italiano: la especialización flexible y los distritos industriales

Incluye Bibliografía

Método dos elementos finitos para determinação da área de contato, entre um rodado e uma superfície deformável

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A sustentabilidade urbana de Maringá/PR: da teoria à prática

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Células solares de ZnO:Ga nanocristalino sensibilizado por corante

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Flexible feeding kinematics of a tropical carnivorous anuran tadpole

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Prototype Fault Current Limiter Using Transformer and a Modular Device of YBCO Coated Conductor

A superconducting fault current limiter (SCFL) consisted of a transformer with low reactance connected to the power line and with the secondary winding short-circuited by a modular superconducting limiter device with 16 elements connected in series was constructed and tested. The designed coupling transformer has low dispersion reactance in order to limit the voltage drop in the power line within the range of 5 % to 10 %. The experimental results showed that an insertion of a 0.125 Omega resistance limited the peak current to a factor of 2.5 times of the unlimited current. The power dissipation reached 39 kW during 100 ms, with an energy density of 380 J/cm(3). Based on these results, the SCFL will be further tested in a 3 MVA (15 kV/380 V) generator for currents up to 10 kA.

Demonstration of non-collocated vibration control of a flexible manipulator using electrical dynamic absorbers

This paper describes an experimental study into the vibration control of a servo system comprising a servo motor and a flexible manipulator. Two modes of the system are controlled by using the servo motor and an accelerometer attached to the tip of the flexible manipulator. The control system is thus non-collocated. It consists of two electrical dynamic absorbers, each of which consists of a modal filter and, in case of an out-of-phase mode, a phase inverter. The experimental results show that each absorber acts as a mechanical dynamic vibration absorber attached to each mode and significantly reduces the settling time for the system response to a step input.

The restructuring of labour in Brazil in the 2000s: flexible work and the precarisation of working life

This article argues that the precarisation of employment that has taken place in Brazil since the 1990s has been fundamentally different in kind from earlier forms of precariousness, which took place outside the formal economy. The new forms of precariousness are taking place within the sphere of the economy controlled by transnational corporations. Although they have only reached critical mass during the 2000s, the ground was prepared by ‘post neoliberal’ restructuring, including labour law reforms, that took place in Brazil during the 1990s and introduced new forms of flexible working. The article argues that the new condition of labour now emerging in Brazil, which is a structural feature of labour under global capitalism, is characterised by psychosocial dynamics that cause: first, class desubjectivation; second, a ‘seizure’ of the waged worker's subjectivity; and third, the reduction of living labour to the status of a workforce treated as goods. Comprehending these changes necessitates a related change in the theoretical and methodological framework in which the precariousness of work is studied, one that incorporates within its scope the issues of workers' health and the quality of working life.

Cardiac autonomic responses induced by a single bout of exercise with flexible pole

Background: Flexible poles are tools used to provide rapid eccentric and concentric muscle contractions. It lacks in the literature studies that analyze acute cardiovascular responses in different exercises performed with this instrument. It was investigated the acute effects of exercise with flexible poles on heart period in healthy women. Methods: The study was performed on 32 women between 18 and 25 years old. It was evaluated the heart rate variability (HRV) in the time (SDNN, RMSSD and pNN50) and frequency domain (HF, LF and LF/HF ratio). The subjects remained at rest for 10 minutes. After the rest period, the volunteers performed the exercises with the flexible poles. Immediately after the exercise protocol, the volunteers remained seated at rest for 60 minutes and HRV were analyzed. Results: It was observed no significance changes in the time domain (SDNN: p = 0.14; RMSSD: p = 0.8 and pNN50: p = 0.86) and frequency domain indices (LF (nu): 0.4; LF (ms2): p = 0.34; HF (nu): p = 0.4; HF (ms2): p = 0.8 and LF/HF ratio: p = 0.3) between before and after single bout of exercise with flexible pole. Conclusion: A single bout of exercise with flexible pole did not significantly change cardiac autonomic regulation in healthy women.