Diffusion controlled inhibition of electrodeposition: impedance measurements

At low rotation speeds of a rotating disc electrode the diffusion-controlled inhibition of zinc deposition by lead acetate or tetrabutylammonium bromide emphasizes the existence of multiple steady states. With both zinc and nickel deposition, low frequency impedance measurements reveal an additional inductive loop associated with a diffusion-controlled inhibition of electrodeposition. From the relaxation time constant it has been concluded that this loop arises from a coupling between the inhibitor diffusion and interfacial processes slower than diffusion and involving, at least for zinc deposition, the slow renewal of active growth sites.     

Actions and Roles of FSH in Germinative Cells

Follicle stimulating hormone (FSH) is produced by the pituitary gland in a coordinated hypothalamic–pituitary–gonadal (HPG) axis event, plays important roles in reproduction and germ cell development during different phases of reproductive development (fetal, neonatal, puberty, and adult life), and is consequently essential for fertility. FSH is a heterodimeric glycoprotein hormone of two dissociable subunits, α and β. The FSH β-subunit (FSHβ) function starts upon coupling to its specific receptor: follicle-stimulating hormone receptor (FSHR). FSHRs are localized mainly on the surface of target cells on the testis and ovary (granulosa and Sertoli cells) and have recently been found in testicular stem cells and extra-gonadal tissue. Several reproduction disorders are associated with absent or low FSH secretion, with mutation of the FSH β-subunit or the FSH receptor, and/or its signaling pathways. However, the influence of FSH on germ cells is still poorly understood; some studies have suggested that this hormone also plays a determinant role in the self-renewal of germinative cells and acts to increase undifferentiated spermatogonia proliferation. In addition, in vitro, together with other factors, it assists the process of differentiation of primordial germ cells (PGCLCs) into gametes (oocyte-like and SSCLCs). In this review, we describe relevant research on the influence of FSH on spermatogenesis and folliculogenesis, mainly in the germ cell of humans and other species. The possible roles of FSH in germ cell generation in vitro are also presented.     

Factors associated with adiposity in normal weight female adolescents with adequate and high percent body fat: elaborating a risk model

Factors associated with adiposity in normal weight female adolescents with adequate and high percent body fat: elaborating a risk model. This study was carried out to evaluate the factors associated with adiposity in normal weight adolescents presenting appropriate or high percent body fat, who attended the public schools in Vi?osa county-Minas Gerais/Brazil. A total of 118 female adolescents at age range from 14 to 19 years and have already presented the menarche were evaluated. The adolescents were divided into 2 groups: G1 with high percent body fat and G2 with appropriate percent body fat. The following variables were evaluated: anthropometric, body composition, lifestyle and the family history of non-communicable chronic diseases. In subsample, the basal energy consumption was determined by indirect calorimetry. The G1-grouped adolescents showed higher values for most anthropometric and body composition variables (p < 0.001). No differences were observed (p > 0.05) for basal metabolism and metabolism of lean body mass, smoking habit, total energy consumption and protein and lipid as well between groups. When comparing the physical activity level, the G1 adolescents spent more time with 1-level sedentary activities whereas the G2 ones showed higher total caloric consumption with daily activities (p < 0.001). According to risk factors under analysis, the variables related to lifestyle, as distinguishing the use of sweeteners (OR = 13.47), provided higher contribution to excessive adiposity in the normal weight adolescents. The detailed analysis of the body composition as well as the risk factors associated with excessive body fat makes possible the early diagnosis and the development of more appropriate intervention means.     

The Brazilian experience with a photovoltaic powered reverse osmosis plant

This article describes a system that combines the technologies of reverse osmosis and photovoltaics to realize a pioneer project for drinking water supply to a rural community in semi‐arid Brazil (latitude 3°44′S), with a local yearly average temperature of 28°C and a yearly solar potential of about 2000 kW h m⁻². Two strategies are investigated: first the PV‐RO (photovoltaic powered reverse osmosis) plant is equipped with a DC motor; and second, a three‐phase induction motor is used. Through the analysis of the stored data the second option is chosen as the better alternative. This strategy has a specific electrical consumption (energy required to produce 1 m³ drinking water) of 3·03 kW h m⁻³, a recovery ratio of 27% (relation between drinking water product flow and brackish water input flow) and a drinking water cost of US$ 12·76 per m³. Copyright © 2004 John Wiley & Sons, Ltd.     

Dispersion characteristics of substrate integrated rectangular waveguide

Dispersion properties of the substrate integrated rectangular waveguide (SIRW) are rigorously obtained using the BI-RME method combined with the Floquet's theorem. Our analysis shows that the SIRW basically has the same guided-wave characteristics as the conventional rectangular waveguide. Empirical equations are derived from the calculated dispersion curves in order to estimate the cutoff frequency of the first two dominant modes of the SIRW To validate the analysis results, an SIRW guide was designed and measured. Very good agreements between the experimental and theoretical results were obtained.