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Oliveira S.V.G.,Regional University of Blumenau | Barbi I.,Federal University of Santa Catarina
IEEE Transactions on Industrial Electronics | Year: 2011

This paper presents a new three-phase step-up dc-dc converter with a three-phase high-frequency (HF) isolation transformer in an average current-mode controlled closed loop. This converter was developed for industrial applications where the dc input voltage is lower than the output voltage, for instance, in installations fed by battery units, photovoltaic arrays, or fuel cell systems. The converter's main characteristics are reduced input ripple current, step-up voltage, HF transformer, reduced output-voltage ripple due to three-pulse output current, and the presence of only three active switches connected to the same reference, this being a main advantage of this converter. By means of a specific switch modulation, the converter allows two operational regions, each one depending upon the number of switches in overlapping conditions-if there are two switches, it is called R2 region, and if there are three switches, it is called R3 region. An average current-mode control strategy is applied to input-current and output-voltage regulation. Theoretical expressions and experimental results are presented for a 6.8-kW prototype, operating in the R2 region, and for a 3.4-kW prototype, operating in the R3 region, both in continuous conduction mode. © 2009 IEEE. Source


Arbuscular mycorrhizal fungi (AMF) are grouped in a monophyletic group, the phylum Glomeromycota. In this review, the history and complexity of the taxonomy and systematics of these obligate biotrophs is addressed by recognizing four periods. The initial discovery period (1845-1974) is characterized by description mainly of sporocarp-forming species and the proposal of a classification for these fungi. The following alpha taxonomy period (1975-1989) established a solid morphological basis for species identification and classification, resulting in a profuse description of new species and a need to standardize the nomenclature of spore subcellular structures. The cladistics period from 1990 to 2000 saw the first cladistic classification of AMF based on phenotypic characters only. At the end of this period, genetic characters played a role in defining taxa and elucidating evolutionary relationships within the group. The most recent phylogenetic synthesis period (2001 to present) started with the proposal of a new classification based on genetic characters using sequences of the multicopy rRNA genes. © 2012 Springer-Verlag. Source


Nasser N.,Regional University of Blumenau
Anais Brasileiros de Dermatologia | Year: 2010

BACKGROUND: It is well established that UV radiation provokes an immunological depletion in the skin, enabling the development of malignant cutaneous tumors. Most nonmelanoma skin cancer patients are considered to be UVB-susceptible. OBJECTIVE: To study the behavior of UVB- susceptibility in malignant melanoma (MM) patients and whether this is a risk factor to the development of MM. METHODS- Eighty-eight volunteers were selected and divided into two groups: healthy control group (n = 61) and MM group (n = 27), which were identified according to the following clinical criteria: histopathological type, level of invasion, skin phototype, sex and age. Susceptibility to ultraviolet B (UVB) radiation was measured by the onset of a contact hypersensitivity reaction to diphenylcyclopropenone among individuals sensitized in previously irradiated areas. RESULTS - Susceptibility to UVB radiation was 81.5 in the MM group and 31.2% in the control group. The risk of an UVB-susceptible individual to develop MM was 9.7 times higher than when UVB resistant. CONCLUSION - UVB susceptibility should be considered an important risk factor to the development of this type of cancer. ©2010 by Anais Brasileiros de Dermatologia. Source


BACKGROUND: Warts are epithelial proliferations in the skin and mucous membrane caused by various types of HPV. They can decrease spontaneously or increase in size and number according to the patient's immune status. The Propionium bacterium parvum is a strong immune stimulant and immune modulator and has important effects in the immune system and it is able to produce antibodies in the skin. OBJECTIVE: To show the efficacy of the Propionium bacterium parvum in saline solution in the treatment of skin warts. METHODS: A randomized double-blind study. Twenty patients with multiple warts were divided into two groups: one received 0,1ml intradermal injection of placebo solution in just one of the warts and the other received 0,1 ml of saline solution of Propionium bacterium parvum, one dose a month, for 3 to 5 months. RESULTS: Among the 20 patients who participated in the study, ten received the placebo and ten received the saline solution with Propionium bacterium parvum. In 9 patients treated with the Propionium bacterium parvum solution the warts disappeared without scars and in 1 patient it decreased in size. In 9 patients who received the placebo no change to the warts was observed and in 1 it decreased in size. CONCLUSIONS: The immune modulator and immune stimulant Propionium bacterium parvum produced antibodies in the skin which destroyed the warts without scars, with statistically significant results (P<0,001), and cured 90 % of the patients. We suggest the use of the immune stimulant in the treatment of warts. © 2012 by Anais Brasileiros de Dermatologia. Source


Hausmann R.,Regional University of Blumenau | Barbi I.,Federal University of Santa Catarina
IEEE Transactions on Power Electronics | Year: 2011

A new three-phase multilevel dc-ac converter with four-state switching cell is presented in this paper. Initially, the power stage diagram is presented and discussed. Its main characteristics are described and the more relevant waveforms, generated by simulation, are shown. After that, the converter operation is presented and all topological states are shown. The vectorial interpretation of the load voltage is shown to all available vectors of load voltage in the new topology. Next, the operation of the converter with sinusoidal pulse width modulation is discussed and some relevant figures are presented. In the sequence, the four-state switching cell is presented and the presence of the three-phase coupled inductor to provide significant reduction in harmonic distortion is discussed. A prototype with 15-kW output power was build with switching frequency equal to 9 kHz and dc link voltage was 300 V. Finally, the related results obtained from the implemented prototype are presented and briefly discussed. © 2011 IEEE. Source

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