Brushless speed control for a novel brazilian axial ventricular assist device

OBJECTIVES: The reduction in size of these systems, which increases their reliability, biocompatibility and robustness, is essential to the complete implantation of the VADs, which is the main focus of the current state of art. Continuous flow VADs are actuated by brushless motors due to their reliability. The objective of the current project was to implement and simulate sensorless speed control in order to actuate VAD. METHODS: In order to increase the robustness of the system even further, a strategy that does not use Hall sensors can be implemented. The sensorless strategy to control speed that was implemented in this work aims to detect the position of the rotor by using the coil of the inactive phase in order to sense the variation in magnetic flux, which comes in the form of back-electromotive forces. RESULTS: A three phase inverter to electrically commute the motor's phases, a conditioning circuit that obtains the back-electromotive forces and a speed controller were developed. The speed control and the commutation logic were implemented by using a microcontroller. The results that were obtained in computational simulations indicated that the three-phase inverter, the commutation logic and the controller reached the project requirements. The implemented microcontroller commutation logic presented the expected behavior. Commutation signals were obtained in six stages, necessary for the correct activation of the phases of the brushless motor. The controller was validated in terms of its step response, demonstrating low overshoot and fast control action in the system. CONCLUSIONS: To further enhance the robustness of the system, an alternative strategy that eliminates the use of Hall sensors can be employed. The sensorless speed control strategy, implemented in this study, detects the position of the rotor by measuring variations in magnetic flux through the coil of the inactive phase, thus relying on back-electromotive forces for detection.

Vibrational spectroscopy as a direct stereochemical probe for polyhydroxylated molecules.

A simple IR and VCD spectra-structure relationship is proposed for the determination of the relative and absolute configurations of polyhydroxylated molecules using a series of styryl-pyrones as model compounds. Spectral signatures identified for free molecules and acetonide derivatives may be used for stereochemical assignments of related molecules without the aid of quantum-chemical calculations.

Solving ethanol production problems with genetically modified yeast strains

The current world demand for bioethanol is increasing as a consequence of low fossil fuel availability and a growing number of ethanol/gasoline flex-fuel cars. In addition, countries in several parts of the world have agreed to reduce carbon dioxide emissions, and the use of ethanol as a fuel (which produces fewer pollutants than petroleum products) has been considered to be a good alternative to petroleum products. The ethanol that is produced in Brazil from the first-generation process is optimized and can be accomplished at low cost. However, because of the large volume of ethanol that is produced and traded each year, any small improvement in the process could represent a savings of billions dollars. Several Brazilian research programs are investing in sugarcane improvement, but little attention has been given to the improvement of yeast strains that participate in the first-generation process at present. The Brazilian ethanol production process uses sugarcane as a carbon source for the yeast Saccharomyces cerevisiae. Yeast is then grown at a high cellular density and high temperatures in large-capacity open tanks with cells recycle. All of these culture conditions compel the yeast to cope with several types of stress. Among the main stressors are high temperatures and high ethanol concentrations inside the fermentation tanks during alcohol production. Moreover, the competition between the desired yeast strains, which are inoculated at the beginning of the process, with contaminants such as wild type yeasts and bacteria, requires acid treatment to successfully recycle the cells. This review is focused on describing the problems and stressors within the Brazilian ethanol production system. It also highlights some genetic modifications that can help to circumvent these difficulties in yeast.

Solving ethanol production problems with genetically modified yeast strains.

The current world demand for bioethanol is increasing as a consequence of low fossil fuel availability and a growing number of ethanol/gasoline flex-fuel cars. In addition, countries in several parts of the world have agreed to reduce carbon dioxide emissions, and the use of ethanol as a fuel (which produces fewer pollutants than petroleum products) has been considered to be a good alternative to petroleum products. The ethanol that is produced in Brazil from the first-generation process is optimized and can be accomplished at low cost. However, because of the large volume of ethanol that is produced and traded each year, any small improvement in the process could represent a savings of billions dollars. Several Brazilian research programs are investing in sugarcane improvement, but little attention has been given to the improvement of yeast strains that participate in the first-generation process at present. The Brazilian ethanol production process uses sugarcane as a carbon source for the yeast Saccharomyces cerevisiae. Yeast is then grown at a high cellular density and high temperatures in large-capacity open tanks with cells recycle. All of these culture conditions compel the yeast to cope with several types of stress. Among the main stressors are high temperatures and high ethanol concentrations inside the fermentation tanks during alcohol production. Moreover, the competition between the desired yeast strains, which are inoculated at the beginning of the process, with contaminants such as wild type yeasts and bacteria, requires acid treatment to successfully recycle the cells. This review is focused on describing the problems and stressors within the Brazilian ethanol production system. It also highlights some genetic modifications that can help to circumvent these difficulties in yeast.

Chemopreventive activity of compounds extracted from Casearia sylvestris (Salicaceae) Sw against DNA damage induced by particulate matter emitted by sugarcane burning near Araraquara, Brazil.

Ethanolic extract of Casearia sylvestris is thought to be antimutagenic. In this study, we attempted to determine whether this extract and casearin X (a clerodane diterpene from C. sylvestris) are protective against the harmful effects of airborne pollutants from sugarcane burning. To that end, we used the Tradescantia micronucleus test in meiotic pollen cells of Tradescantia pallida, the micronucleus test in mouse bone marrow cells, and the comet assay in mouse blood cells. The mutagenic compound was total suspended particulate (TSP) from air. For the Tradescantia micronucleus test, T. pallida cuttings were treated with the extract at 0.13, 0.25, or 0.50 mg/ml. Subsequently, TSP was added at 0.3mg/ml, and tetrads from the inflorescences were examined for micronuclei. For the micronucleus test in mouse bone marrow cells and the comet assay in mouse blood cells, Balb/c mice were treated for 15 days with the extract-3.9, 7.5, or 15.0 mg/kg body weight (BW)-or with casearin X-0.3, 0.25, or 1.2 mg/kg BW-after which they received TSP (3.75 mg/kg BW). In T. pallida and mouse bone marrow cells, the extract was antimutagenic at all concentrations tested. In mouse blood cells, the extract was antigenotoxic at all concentrations, whereas casearin X was not antimutagenic but was antigenotoxic at all concentrations. We conclude that C. sylvestris ethanolic extract and casearin X protect DNA from damage induced by airborne pollutants from sugarcane burning.

In vitro interactions between amphotericin B and other antifungal agents and rifampin against Fusarium spp.

Fusarium species are common hyaline soil saprophytes and plant pathogens that are opportunistic fungal pathogens of immunocompromised patients. The treatment for fusariosis remains uncertain with an unfavourable prognosis; new possibilities for treatment, such as various synergistic drug interactions, must be uncovered. In this study, we evaluated the in vitro interactions of amphotericin B with caspofungin, ketoconazole, 5-flucytosine, itraconazole, miconazole, rifampin, fluconazole, terbinafine and voriconazole against isolates of Fusarium spp. using the chequerboard method with interactions evaluated by fractional inhibitory concentration indices. The highest percentages of synergistic interactions were observed for the combinations of amphotericin B and caspofungin (68.7%), amphotericin B and rifampin (68.7%), amphotericin B plus 5-flucytosine (59.3%) and amphotericin B with voriconazole (37.5%). The pattern of susceptibility to antifungal agents among Fusarium species and their consequence on the effects of drug combinations are also discussed.

Antinociceptive effect on mice of the hydroalcoholic fraction and (-) epicatechin obtained from Combretum leprosum Mart & Eich.

Previous studies on Combretum leprosum, a tree growing in the Northeastern states of Brazil, have shown antinociceptive effects of the ethanol extract of its leaves and bark, but studies examining its constituents are rare. The objective of this study was to evaluate the antinociceptive effect of the hydroalcoholic fraction (HF) of one of its constituents, the flavonoid (-) epicatechin (EPI), administered orally to mice (20-30 g) in models of chemical nociception, and the possible mechanisms involved. Different doses of HF (62.5 to 500 mg/kg) and EPI (12.5 to 50 mg/kg) were evaluated in models of abdominal writhing, glutamate, capsaicin, and formalin in animals pretreated with different antagonists: naloxone, ondansetron, yohimbine, ketanserin, pindolol, atropine, and caffeine in the abdominal writhing test. To determine the role of nitric oxide, the animals were pretreated with L-arginine (600 mg/kg, ip) in the glutamate test. The HF was effective (P < 0.05) in all protocols at different doses and EPI was effective in the abdominal writhing, capsaicin and glutamate tests (P < 0.05) at doses of 25 and 50 mg/kg. However, in the formalin test it was only effective in the second phase at a dose of 25 mg/kg. The antinociceptive effect of HF was inhibited when HF was associated with yohimbine (0.15 mg/kg), ketanserine (0.03 mg/kg), and L-arginine (600 mg/kg), but not with the other antagonists. HF and EPI were effective in models of chemical nociception, with the suggested participation of the adrenergic, serotonergic and nitrergic systems in the antinociceptive effect of HF.

Antinociceptive effect on mice of the hydroalcoholic fraction and (-) epicatechin obtained from Combretum leprosum Mart & Eich

Previous studies on Combretum leprosum, a tree growing in the Northeastern states of Brazil, have shown antinociceptive effects of the ethanol extract of its leaves and bark, but studies examining its constituents are rare. The objective of this study was to evaluate the antinociceptive effect of the hydroalcoholic fraction (HF) of one of its constituents, the flavonoid (-) epicatechin (EPI), administered orally to mice (20-30 g) in models of chemical nociception, and the possible mechanisms involved. Different doses of HF (62.5 to 500 mg/kg) and EPI (12.5 to 50 mg/kg) were evaluated in models of abdominal writhing, glutamate, capsaicin, and formalin in animals pretreated with different antagonists: naloxone, ondansetron, yohimbine, ketanserin, pindolol, atropine, and caffeine in the abdominal writhing test. To determine the role of nitric oxide, the animals were pretreated with L-arginine (600 mg/kg, ip) in the glutamate test. The HF was effective (P < 0.05) in all protocols at different doses and EPI was effective in the abdominal writhing, capsaicin and glutamate tests (P < 0.05) at doses of 25 and 50 mg/kg. However, in the formalin test it was only effective in the second phase at a dose of 25 mg/kg. The antinociceptive effect of HF was inhibited when HF was associated with yohimbine (0.15 mg/kg), ketanserine (0.03 mg/kg), and L-arginine (600 mg/kg), but not with the other antagonists. HF and EPI were effective in models of chemical nociception, with the suggested participation of the adrenergic, serotonergic and nitrergic systems in the antinociceptive effect of HF.

Identificação de diterpenos clerodânicos em diferentes órgãos de Casearia sylvestris Swartz / Identification of clerodane diterpenes in different organs of Casearia sylvestris Swartz

Casearia sylvestris Swartz (Salicaceae) é uma espécie vegetal arbórea ou arbustiva, disseminada pelo território brasileiro e bastante utilizada em nossa medicina popular. Diversos diterpenos clerodânicos bioativos típicos do gênero Casearia foram isolados desta espécie (ex. casearinas e casearvestrinas). O objetivo principal deste trabalho foi avaliar a presença de diterpenos clerodânicos em diferentes órgãos de C. sylvestris, utilizando técnicas analíticas cromatográficas e espectroscópicas. Os extratos dos diferentes órgãos foram analisados por cromatografia em camada delgada, cromatografia líquida de alta eficiência com detector de arranjo de diodos e ressonância magnética nuclear de 1H. Nas análises cromatográficas foram utilizados diterpenos clerodânicos isolados de C. sylvestris como padrões, incluindo rel-19S-acetóxi- 18R- butanoilóxi- 18,19- epóxi -6S -hidróxi -2R- (2-metilbutanoilóxi) -5S, 8R, 9R, 10S -cleroda-3,13(16),14-trieno, isolado do caule pela primeira vez. Foram obtidos perfis fitoquímicos dos órgãos avaliados. Os resultados indicaram a presença de diterpenos clerodânicos em toda planta, prevalecendo em maior número nas folhas. Além disso, os resultados também indicam que em caules, flores e raízes há predomínio de diterpenos clerodânicos com padrão diênico diferente daqueles obtidos de folhas de C. sylvestris.

Casearia sylvestris Swartz (Salicaceae) is a tree or shrub distributed widely in Brazil, where it is used in popular medicine. Several bioactive clerodane diterpenes typical of Casearia have been isolated from this species (e.g. casearins and casearvestrins). The main objective of this study was to identify clerodane diterpenes in various organs of C. sylvestris, using chromatographic and spectroscopic analytical techniques. The extracts of the different plant parts were analyzed by thin layer chromatography, high performance liquid chromatography with diode array detector and 1H nuclear magnetic resonance. In the chromatographic analysis, clerodane diterpenes isolated from C. sylvestris were used as standards, including rel-19Sacetóxi- 18R- butanoilóxi-18,19- epóxi -6S -hidróxi -2R- (2-metilbutanoilóxi) -5S, 8R, 9R, 10S -cleroda-3,13(16),14- triene, isolated for the first time from the stems. Phytochemical profiles of the organs were produced, which indicated the presence of clerodane diterpenes in all parts of the plant, notably in the leaves. The results also suggest that the main clerodane diterpenes in the stems, flowers and roots had conjugated double-bond patterns that differed from those found in the leaves.

Cryptomoscatona D2 de Cryptocarya mandioccana: atividade citotóxica contra linhagem celular de carcinoma cervical humano / Cryptomoschatone D2 from Cryptocarya mandioccana: cytotoxicity against human cervical carcinoma cell lines

Among the substances isolated from Cryptocarya sp, some styrylpyrones, such as goniothalamin, demonstrate antiproliferative activity in a broad range of human cell lines. In the present study, we assessed the cytotoxicity of a styrylpyrone (cryptomoschatone D2), isolated from Cryptocarya mandiocanna, in HPV-infected (HeLa and SiHa) and uninfected (C33A) human cervical carcinoma cell lines and a human lung fibroblast line (MRC-5). The cytotoxicity was tested by the MTT assay. In this assay, cells were treated with cryptomoschatone D2 at 15, 30, 60 or 90 ?M for 6, 24 or 48 hours, as well as for 6 hours followed by a post-treatment recovery period of 24, 48 or 72 hours. High cytotoxicity (dose- and timedependent) was observed in HeLa, SiHa, C33A and MRC-5 cell lines. Although in general the styrylpyrone cytotoxicity was not significantly different among the cell lines tested, it was apparently stronger in HeLa and C33A than in MRC-5 and SiHa in the 24 or 48-hour treatments. Moreover, HeLa and SiHa were able to recover their ability to proliferate, in direct proportion to the post-treatment recovery time. On the other hand, C33A did not demonstrate a similar post-treatment recovery. We can conclude that cryptomoschatone D2 possesses high dose-dependent or time-dependent cytotoxicity.

Dentre as substâncias isoladas de Cryptocarya sp, algumas estirilpironas, como a goniotalamina, apresentam atividade antiproliferativa em diferentes linhagens celulares. No presente estudo, foram avaliadas as atividades citotóxica de uma estirilpirona (criptomoscatona D2) isolada de Cryptocarya mandiocanna, em linhagens celulares de carcinoma cervical humano infectada por HPV (HeLa e SiHa), não infectada (C33A) e fibroblasto pulmonar humano (MRC-5). A atividade citotóxica foi avaliada pelo ensaio do MTT. No ensaio do MTT, as células foram tratadas com criptomoscatona D2 em 15, 30, 60 e 90 ?M por 6, 24 e 48 horas e por 6 horas com período de recuperação de 24, 48 e 72 horas pós-tratamento. O tratamento com a estirilpirona (criptomoscatona D2) ocasionou elevada citotoxicidade dose-resposta e tempo-resposta em HeLa, SiHa, C33A e MRC-5. Embora não haja diferença estatisticamente significativa de citotoxicidade entre as linhagens, aparentemente a citotoxicidade foi maior em HeLa e C33A (tratamento de 24 e 48 horas) que em MRC-5 e SiHa. Ainda, no período de recuperação, HeLa e SiHa aparentemente restabelecem sua capacidade proliferativa, que é diretamente proporcional ao tempo de recuperação, enquanto o mesmo comportamento não é observado em C33A. Estes resultados sugerem que criptomoscatona D2 possui elevada atividade antiproliferativa dose-resposta ou o tempo resposta.

Caracterização biométrica e química da folha de Mentha pulegium x spicata (Lamiaceae) / Biometric and chemical characterization of Mentha pulegium x spicata (lamiaceae) leaves

O híbrido Mentha pulegium x spicata, também conhecido como poejo de praia, é uma planta perene, rasteira, ramosa, com caule arroxeado, folhas opostas, lanceoladas e serreadas no bordo, apresentando odor característico. O objetivo do presente trabalho foi realizar um estudo da anatomia foliar, incluindo um estudo de biometria tecidual e análise quantitativa de tricomas secretores/mm2 e de estômatos/mm2 em ambas as faces da folha, além de uma análise química do óleo essencial. Foram efetuadas lâminas permanentes para análise anatômica do limbo foliar e também lâminas da impressão foliar para a contagem do número de tricomas e estômatos. A análise química foi efetuada através da extração do óleo essencial por arraste à vapor d'água e analisado por CG-EM. Os tricomas capitados e peltados estão presentes em ambas as faces da folha, porém predominam na superfície abaxial. A análise de variância mostrou que há diferenças significativas para o número de tricomas capitados e tectores entre as superfícies adaxial e abaxial, mas não são significativas para o tricoma peltado. O óleo essencial analisado, mostra a presença do componente majoritário, trans-epóxido de piperitona, responsável por mais de 80% da composição relativa no óleo bruto

Antifungal amides from Piper hispidum and Piper tuberculatum.

Piper hispidum and Piper tuberculatum accumulate amides bearing isobutyl, pyrrolidine, dihydropyridone and piperidine moieties. The isolation and characterization of several representatives including two hitherto unreported amides were performed by chromatographic techniques and by analysis of spectroscopic data. The antifungal activity of each amide was determined by direct bioautography against Cladosporium sphaerospermum.

6-[omega-arylalkenyl]-5,6-dihydro-alpha-pyrones from Cryptocarya moschata (Lauraceae).

Eleven 6-[omega-arylalkenyl]-5,6-dihydro-alpha-pyrones, cryptomoscatones D2, E1, E2, E3 and F1 and cryptopyranmoscatones A1, A2, A3, B1, B2 and B4, in addition to goniothalamin and cryptofolione, were isolated from branch and stem bark of Cryptocarya moschata, Lauraceae. Their structures were established by spectroscopic methods.

Search for antifungal and anticancer compounds from native plant species of Cerrado and Atlantic Forest.

Bioactivity-guided fractionation of several bioactive extracts obtained from Cerrado and Atlantic Forest plant species led to the isolation of potent DNA-damaging piperidine 1-5 and guanidine alkaloids 6-9 from Cassia leptophylla and Pterogyne nitens respectively, two common Leguminosae from Atlantic Forest. By means of biotechnological approach on Maytenus aquifolium, a species from Cerrado, moderate DNA-damaging sesquiterpene pyridine alkaloid 10-11 was isolated. Bioassay-guided fractionation on Casearia sylvestris, a medicinal plant species found in Cerrado and Atlantic Forest, led to the isolation of clerodane diterpenes 12-13 which showed effect on DNA. In addition, we have reported several interesting potent antifungal iridoids: 1 beta-hydroxy-dihydrocornin (14), 1 alpha-hydroxy-dihydrocornin (15), alpha-gardiol (16), beta-gardiol (17), plumericin (18), isoplumericin (19), 11-O-trans-caffeoylteucrein (20); ester derivative: 2-methyl-4-hydroxy-butyl-caffeoate (21), amide N-[7-(3',4'-methylenedioxyphenyl)-2Z, 4Z-heptadienoyl] pyrrolidine (22) and triterpene viburgenin (23).

A chromene and prenylated benzoic acid from Piper aduncum.

In addition to nerolidol, 2',6'-dihydroxy-4'-methoxydihydrochalcone, methyl 2,2-dimethyl-8-(3'-methyl-2'-butenyl)-2H-1-chromene-6-carboxylate, methyl 2,2-dimethyl-2H-1-chromene-6-carboxylate and methyl 8-hydroxy-2,2-dimethyl-2H-1-chromene-6-carboxylate, two new natural products were isolated from the leaves of Piper aduncum, 2,2-dimethyl-2H-1-chromene-6-carboxylic acid and 3-(3',7'-dimethyl-2',6'-octadienyl)-4-methoxybenzoic acid. The structures of the isolates were established based on analysis of spectroscopic data, including ES-MS. The DNA-damaging activity of the isolated compounds was also investigated against mutant strains of Saccharomyces cerevisiae.