Presence and levels of galactosyllactoses and other oligosaccharides in human milk and their variation during lactation and according to maternal phenotype

Among the human milk oligosaccharides (HMOS), the galactosyllactoses (GLs) are only limitedly studied. This study aims to describe the presence and relative levels of HMOS, including GLs, in human milk (HM) according to maternal Secretor and Lewis (SeLe) phenotype and lactation stage. Relative levels of 19 HMOS were measured in 715 HM samples collected in the first 4 months postpartum from 371 donors participating in the PreventCD study. From a subset of 24 Dutch women (171 HM samples), samples were collected monthly up to 12 months postpartum and were additionally analyzed for relative and absolute levels of beta 6 '-GL, beta 3 '-GL and alpha 3 '-GL. Maternal SeLe phenotype or HM group was assigned based on the presence of specific fucosylated HMOS. Most HMOS, including beta 6 '- and beta 3 '-GL, were present in the vast majority (>= 75%) of HM samples, whereas others (e.g., LNDFH II, 2 '-F-LNH and alpha 3 '-GL) only occurred in a low number (<25%) of samples. Clear differences were observed between the presence and relative levels of the HMOS according to the maternal phenotype and lactation stage. Absolute concentrations of beta 6 '-GL and beta 3 '-GL were higher in HM group IV samples compared to samples of the other three HM groups. beta 3 '-GL was also higher in HM group II samples compared to HM group I samples. beta 3 '-GL and beta 6 '-GL were stable over lactation stages. In conclusion, presence and levels of HMOS vary according to HM group and lactation stage. Not all HMOS behave similarly: some HMOS depend strongly on maternal phenotype and/or lactation stage, whereas others do not. beta 3 '-GL and beta 6 '-GL were present in low concentrations in over 75% of the analyzed HM samples and showed differences between HM groups, but not between the lactation stages.Transplantation and immunomodulatio

Estudo do conversor zeta em condu??o simult?nea dos semicondutores aplicada ? alimenta??o de LEDs de pot?ncia

Submitted by Setor de Tratamento da Informa??o - BC/PUCRS ([email protected]) on 2015-06-17T12:02:56Z No. of bitstreams: 1 470517 - Texto Completo.pdf: 3643142 bytes, checksum: 1f5335f433b80cbcbe58f559422c4f72 (MD5)Made available in DSpace on 2015-06-17T12:02:56Z (GMT). No. of bitstreams: 1 470517 - Texto Completo.pdf: 3643142 bytes, checksum: 1f5335f433b80cbcbe58f559422c4f72 (MD5) Previous issue date: 2015-01-07Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPESThis work presents the simultaneous conduction mode (SCM), which is applied to the operation of the Zeta converter. This mode has the ability to implement an ideal power factor corrector (PFC) employing only one feedback control loop. In SCM, the current in the main switch and in the diode flows simultaneously within one of the operation stages. In SCM, the power converter presents characteristics of both conduction modes: continuous conduction mode (CCM) and discontinuous conduction mode (DCM). In SCM, the currents in the inductors of the power converter are never nullified, which is a typical behavior of the CCM. Nevertheless, the SCM does that while obtaining an ideal PFC with just one control loop. The SCM maintains its features, regardless of its control variable being the output current or the output voltage of the power converter. The solely application of a fixed duty cycle controller is enough to attain all these advantages, which is usually a feature of the DCM for PFCs of the flyback family. In order to validate the proposed technique, a complete study of the Zeta converter working in this new operation mode was performed.This study has included a qualitative and a quantitative power converter analysis. These analyses resulted in the development of a design methodology for the Zeta power converter working as a PFC in the SCM. In order to validate the present study, a prototype of the Zeta PFC for operation in the SCM was designed and built. This prototype was developed, as a case of study, to drive a power LED lamp (180?W). Thus, it was obtained the desired experimental confirmation for the research. The main advantage of the SCM, in comparison to the CCM, lies in its ability to maintain the input current of the PFC sinusoidal and in phase with the input voltage, which is imposed by the mains through the use of just a single PWM controller with fixed duty cycle. These results have, also, shown that the current peaks in the main semiconductors of the power converter are lower than their respective values in the DCM. However, this new operation mode results in the increase of the voltages on the main switch and diode in relation to the conventional power converter operation. The research of the application of the proposed method to other power converters is suggested to further works.Este trabalho prop?e a opera??o do conversor Zeta no modo de condu??o simult?nea (MCS), cujo interesse reside na capacidade de implementa??o de um pr?-regulador do fator de pot?ncia (PFP) ideal empregando apenas um la?o de realimenta??o. Quando o conversor trabalha no MCS, a chave principal e o diodo conduzem simultaneamente em um de seus est?gios de opera??o. Neste modo de condu??o, o conversor est?tico apresenta caracter?sticas de ambos os modos de condu??o conhecidos at? agora: o modo de condu??o cont?nua (MCC) e o modo de condu??o descont?nua (MCD). A opera??o no MCS resulta em um conversor est?tico operando como se estivesse no MCC, uma vez que a corrente nos indutores nunca se anula. Embora mantenha o conversor est?tico trabalhando com esta caracter?stica do MCC, o MCS permite a obten??o de um comportamento quase ideal do PFP, utilizando apenas um ?nico controlador, seja ele de corrente ou de tens?o, o qual mant?m a raz?o c?clica do conversor constante, assim como usualmente ocorre com os PFPs da fam?lia redutor-elevador quando operam no MCD.Visando validar esta t?cnica, foi realizado um estudo do conversor operando desta forma que incluiu o desenvolvimento das an?lises qualitativa e quantitativa do conversor, as quais culminaram na elabora??o de uma metodologia de projeto. Assim, realizou-se o projeto de um PFP, baseado no conversor Zeta, para energizar uma lumin?ria LED de 180 W, operando no MCS, como estudo de caso. A lumin?ria utilizada ? o modelo High Power LED Baylight da empresa Luckysunny?. Os resultados obtidos experimentalmente validaram a estrat?gia proposta, uma vez que, com a opera??o do conversor Zeta no MCS reduz-se a ondula??o (ripple) da corrente nos semicondutores em rela??o ? opera??o no MCD. A principal vantagem da opera??o no MCS reside no fato deste manter a corrente de entrada do PFP senoidal em fase com a tens?o imposta pela rede el?trica com apenas uma malha de controle da vari?vel de sa?da de interesse seja ela tens?o ou corrente como no estudo de caso em quest?o. Isto reduz o custo e a complexidade do controlador do conversor. Entretanto, esta estrat?gia apresenta sobretens?o na chave principal e no diodo como principal desvantagem. Sugere-se a investiga??o da aplica??o da metodologia de projeto proposta a outros conversores