On the photoluminescence behavior of samarium-doped strontium titanate nanostructures under UV light. A structural and electronic understanding

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Long term evaluation of morphometric and ultrastructural changes of testes of alloxan-induced diabetic rats

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

Origin of photo luminescence in SrTiO3: a combined experimental and theoretical study

A joint experimental and theoretical study has been carried out to rationalize the photoluminescence properties of SrTiO3 perovskite thin films synthesized through a soft chemical processing. Only the amorphous samples present photoluminescence at room temperature. From the theoretical side, first principles quantum mechanical techniques, based on density functional theory at B3LYP level, have been employed to study the electronic structure of a crystalline (ST-c) and an asymmetric (ST-a) model. Electronic properties are analyzed in the light of the experimental results and their relevance in relation to the PL behavior of ST is discussed. (C) 2004 Elsevier B.V. All rights reserved.

Combined experimental and theoretical study to understand the photoluminescence of Sr1-xTiO3-x

A joint experimental and theoretical study has been carried out to rationalize the results of visible photoluminescence measurements at room temperature on Sr1-xTiO3-x (ST) perovskite thin films. From the experimental side, ST thin films, x = 0 to 0.9, have been synthesized following soft chemical processing, and the corresponding photoluminescence properties have been measured. First principles quantum mechanical techniques, based on density functional theory at the B3LYP level, have been employed to study the electronic structure of a crystalline, stoichiometric (x = 0) ST-s model and a nonstoichiometric (SrO-deficient, x not equal 0) and structurally disordered ST-d model. The relevance of the present theoretical and experimental results of the photoluminescence behavior of ST is discussed. The optical spectra and the calculations indicate that the symmetry-breaking process on going from ST-s to ST-d creates electronic levels in the valence band. Moreover, an analysis of the Mulliken charge distribution reveals a charge gradient in the structure. These combined effects seem to be responsible for the photoluminescence behavior of deficient Sr1-xTiO3-x.

Model peptides mimic the structure and function of the N-terminus of the pore-forming toxin sticholysin II

To investigate the role of the N-terminal region in the lytic mechanism of the pore-forming toxin sticholysin II (St II), we studied the conformational and functional properties of peptides encompassing the first 30 residues of the protein. Peptides containing residues 1-30 (P1-30) and 11-30 (P11-30) were synthesized and their conformational properties were examined in aqueous solution as a function of peptide concentration, pH, ionic strength, and addition of the secondary structure-inducing solvent trifluoroethanol (TFE). CD spectra showed that increasing concentration, pH, and ionic strength led to aggregation of P1-30; as a consequence, the peptide acquired beta-sheet conformation. In contrast, P11-30 exhibited practically no conformational changes under the same conditions, remaining essentially structureless. Moreover, this peptide did not undergo aggregation. These differences clearly point to the modulating effect of the first 10 hydrophobic residues on the peptides aggregation and conformational properties. In TFE both the first ten hydrophobic peptides acquired alpha-helical conformation, albeit to a different extent, P11-30 displayed lower alpha-helical content. P1-30 presented a larger-fraction of residues in alpha-helical conformation in TFE than that found in St II's crystal structure for that portion of the protein. Since TFE mimics the membrane em,, such increase in helical content could also occur upon toxin binding to membranes and represent a step in the mechanism of pore formation. The peptides conformational properties correlated well with their functional behaviour. Thus, P1-30 exhibited much higher hemolytic activity than P11-30. In addition, P11-30 was able to block the toxin's hemolytic activity. The size of pores formed in red blood cells by P 1-30 was estimated by measuring the permeability PEGs of different molecular mass. The pore radius (0.95 +/- 0.01 nm) was very similar to that of the PEGs of different pore formed by the toxin. The results demonstrate that the synthetic peptide P1-30 is a good model of St 11 conformation and function and emphasize the contribution of the toxin's N-terminal region, and, in particular, the hydrophobic residues 1-10 to pore formation. (c) 2005 Wiley Periodicals, Inc.

Analysis of culling probability in dairy buffalo using survival models

In order to contribute to the genetic breeding programs of buffaloes, this study aimed to determine the influence of environmental effects on the stayability (ST) of dairy female Murrah buffalo in the herd. Data from 1016 buffaloes were used. ST was defined as the ability of the female to remain in the herd for 1, 2, 3, 4, 5 or 6 years after the first calving. Environmental effects were studied by survival analysis, adjusted to the fixed effects of farm, year and season of birth, class of first-lactation milk yield and age at first calving. The data were analyzed using the LIFEREG procedure of the SAS program that fits parametric models to failure time data (culling or ST = 0), and estimates parameters by maximum likelihood estimation. Breeding farm, year of birth and first-lactation milk yield significantly influenced (P < 0.0001) the ST to the specific ages (1 to 6 years after the first calving). Buffaloes that were older at first calving presented higher probabilities of being culled 1 year after the first calving, without any effect on culling at older ages. Buffaloes with a higher milk yield at first calving presented a lower culling probability and remained for a longer period of time in the herd. The effects of breeding farm, year of birth and first-lactation milk yield should be included in models used for the analysis of ST in buffaloes. Copyright © The Animal Consortium 2010.

Development banking in the Eastern Caribbean: the case of Saint Lucia and Grenada

Includes bibliography

Multiple-trait random regression models for the estimation of genetic parameters for milk, fat, and protein yield in buffaloes

In this study, genetic parameters for test-day milk, fat, and protein yield were estimated for the first lactation. The data analyzed consisted of 1,433 first lactations of Murrah buffaloes, daughters of 113 sires from 12 herds in the state of São Paulo, Brazil, with calvings from 1985 to 2007. Ten-month classes of lactation days were considered for the test-day yields. The (co)variance components for the 3 traits were estimated using the regression analyses by Bayesian inference applying an animal model by Gibbs sampling. The contemporary groups were defined as herd-year-month of the test day. In the model, the random effects were additive genetic, permanent environment, and residual. The fixed effects were contemporary group and number of milkings (1 or 2), the linear and quadratic effects of the covariable age of the buffalo at calving, as well as the mean lactation curve of the population, which was modeled by orthogonal Legendre polynomials of fourth order. The random effects for the traits studied were modeled by Legendre polynomials of third and fourth order for additive genetic and permanent environment, respectively, the residual variances were modeled considering 4 residual classes. The heritability estimates for the traits were moderate (from 0.21-0.38), with higher estimates in the intermediate lactation phase. The genetic correlation estimates within and among the traits varied from 0.05 to 0.99. The results indicate that the selection for any trait test day will result in an indirect genetic gain for milk, fat, and protein yield in all periods of the lactation curve. The accuracy associated with estimated breeding values obtained using multi-trait random regression was slightly higher (around 8%) compared with single-trait random regression. This difference may be because to the greater amount of information available per animal. © 2013 American Dairy Science Association.

Developments in relation to the proposal for securing the international recognition of the Caribbean sea as a special area in the context of sustainable development

Includes bibliography

An assessment of the economic impact of climate change on the coastal and marine sector in Saint Kitts And Nevis

Owing to their high vulnerability and low adaptive capacity, Caribbean islands have legitimate concerns about their future, based on observational records, experience with current patterns and consequences of climate variability, and climate model projections. Although emitting less than 1% of global greenhouse gases, islands from the region have already perceived a need to reallocate scarce resources away from economic development and poverty alleviation, and towards the implementation of strategies to adapt to the growing threats posed by global warming (Nurse and Moore, 2005). The objectives of this Report are to conduct economic analyses of the projected impacts of climate change to 2050, within the context of the IPCC A2 and B2 scenarios, on the coastal and marine resources of St. Kitts and Nevis (SKN). The Report presents a valuation of coastal and marine services; quantitative and qualitative estimates of climate change impacts on the coastal zone; and recommendations for possible adaptation strategies and costs and benefits of adaptation.

Functional and Topological Studies with Trp-Containing Analogs of the Peptide StII(1-30) Derived From the N-Terminus of the Pore Forming Toxin Sticholysin II: Contribution to Understand its Orientation in Membrane

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Historical Observations of Humpback And Blue Whales in the North Atlantic Ocean: Clues to Migratory Routes and Possibly Additional Feeding Grounds

The seasonal distributions of humpback and blue whales (Megaptera novaeangliae and Balaenoptera musculus, respectively) in the North Atlantic Ocean are not fully understood. Although humpbacks have been studied intensively in nearshore or coastal feeding and breeding areas, their migratory movements between these areas have been largely inferred. Blue whales have only been studied intensively along the north shore of the Gulf of St. Lawrence, and their seasonal occurrence and movements elsewhere in the North Atlantic are poorly known. We investigated the historical seasonal distributions of these two species using sighting and catch data extracted from American 18th and 19th century whaling logbooks. These data suggest that humpback whales migrated seasonally from low-latitude calving/ breeding grounds over a protracted period, and that some of them traveled far offshore rather than following coastal routes. Also, at least some humpbacks apparently fed early in the summer west of the Mid-Atlantic Ridge, well south of their known present-day feeding grounds. In assessing the present status of the North Atlantic humpback population, it will be important to determine whether such offshore feeding does in fact occur. Blue whales were present across the southern half of the North Atlantic during the autumn and winter months, and farther north in spring and summer, but we had too few data points to support inferences about these whales’ migratory timing and routes.

Effects of strength and power training on neuromuscular adaptations and jumping movement pattern and performance

Effects of strength and power training on neuromuscular adaptations and jumping movement pattern and performance. J Strength Cond Res 26(12): 3335-3344, 2012-This study aimed at comparing the effects of strength and power training (ST and PT) regimens on neuromuscular adaptations and changes on vertical jump performance, kinetics, and kinematics parameters. Forty physically active men (178.2 +/- 7.0 cm; 75.1 +/- 8.6 kg; 23.6 +/- 3.5 years) with at least 2 years of ST experience were assigned to an ST (n = 14), a PT (n = 14), or a control group (C; n = 12). The training programs were performed during 8 weeks, 3 times per week. Dynamic and isometric maximum strength, cross-sectional area, and muscle activation were assessed before and after the experimental period. Squat jump (SJ) and countermovement jump (CMJ) performance, kinetics, and kinematics parameters were also assessed. Dynamic maximum strength increased similarly (p < 0.05) for the ST (22.8%) and PT (16.6%) groups. The maximum voluntary isometric contraction increased for the ST and PT groups (p < 0.05) in the posttraining assessments. There was a main time effect for muscle fiber cross-sectional area (p < 0.05), but there were no changes in muscle activation. The SJ height increased, after ST and PT, because of a faster concentric phase and a higher rate of force development (p < 0.05). The CMJ height increased only after PT (p < 0.05), but there were no significant changes in its kinetics and kinematics parameters. In conclusion, neuromuscular adaptations were similar between the training groups. The PT seemed more effective than the ST in increasing jumping performance, but neither the ST nor the PT was able to affect the SJ and the CMJ movement pattern (e.g., timing and sequencing of joint extension initiation).

Thermodynamics of aqueous biopolymer solutions and fractionation of Dextran

Flory-Huggins interaction parameters and thermal diffusion coefficients were measured for aqueous biopolymer solutions. Dextran (a water soluble polysaccharide) and bovine serum albumin (BSA, a water soluble protein) were used for this study. The former polymer is representative for chain macromolecules and the latter is for globular macromolecules. The interaction parameters for the systems water/dextran and water/BSA were determined as a function of composition by means of vapor pressure measurements, using a combination of headspace sampling and gas chromatography (HS-GC). A new theoretical approach, accounting for chain connectivity and conformational variability, describes the observed dependencies quantitatively for the system water/dextran and qualitatively for the system water/BSA. The phase diagrams of the ternary systems water/methanol/dextran and water/dextran/BSA were determined via cloud point measurements and modeled by means of the direct minimization of the Gibbs energy using the information on the binary subsystems as input parameters. The thermal diffusion of dextran was studied for aqueous solutions in the temperature range 15 < T < 55 oC. The effects of the addition of urea were also studied. In the absence of urea, the Soret coefficient ST changes its sign as T is varied; it is positive for T > 45.0 oC, but negative for T < 45.0 oC. The positive sign of ST means that the dextran molecules migrate towards the cold side of the fluid; this behavior is typical for polymer solutions. While a negative sign indicates the macromolecules move toward the hot side; this behavior has so far not been observed with any other binary aqueous polymer solutions. The addition of urea to the aqueous solution of dextran increases ST and reduces the inversion temperature. For 2 M urea, the change in the sign of ST is observed at T = 29.7 oC. At higher temperature ST is always positive in the studied temperature range. To rationalize these observations it is assumed that the addition of urea opens hydrogen bonds, similar to that induced by an increase in temperature. For a future extension of the thermodynamic studies to the effects of poly-dispersity, dextran was fractionated by means of a recently developed technique called Continuous Spin Fractionation (CSF). The solvent/precipitant/polymer system used for the thermodynamic studies served as the basis for the fractionation of dextran The starting polymer had a weight average molar mass Mw = 11.1 kg/mol and a molecular non-uniformity U= Mw / Mn -1= 1.0. Seventy grams of dextran were fractionated using water as the solvent and methanol as the precipitant. Five fractionation steps yielded four samples with Mw values between 4.36 and 18.2 kg/mol and U values ranging from 0.28 to 0.48.

Development and evaluation of a 44 Ti, 44 Sc radionuclide generator and labeling of biomolecules with 44 Sc and 68 Ga for PET imaging

Non-invasive molecular-imaging technologies are playing a key role in drug discovery, development and delivery. Positron Emission Tomography (PET) is such a molecular imaging technology and a powerful tool for the observation of various deceases in vivo. However, it is limited by the availability of vectors with high selectivity to the target and radionuclides with a physical half-life which matches the biological half-life of the observed process. The 68Ge/68Ga radionuclide generator makes the PET-nuclide anywhere available without an on-site cyclotron. Besides the perfect availability 68Ga shows well suited nuclide properties for PET, but it has to be co-ordinated by a chelator to introduce it in a radiopharmaceuticals.rnHowever, the physical half-life of 68Ga (67.7 min) might limit the spectrum of clinical applications of 68Ga-labelled radiodiagnostics. Furthermore, 68Ga-labelled analogues of endoradiotherapeuticals of longer biological half-live such as 90Y- or 177Lu-labeled peptides and proteins cannot be used to determine individual radiation dosimetry directly. rnThus, radionuclide generator systems providing positron emitting daughters of extended physical half-life are of renewed interest. In this context, generator-derived positron emitters with longer physical half-life are needed, such as 72As (T½ = 26 h) from the 72Se/72As generator, or 44Sc (T½ = 3.97 h) from the 44Ti/44Sc generator.rnIn this thesis the implementation of radioactive gallium-68 and scandium-44 for molecular imaging and nuclear medical diagnosis, beginning with chemical separation and purification of 44Ti as a radionuclide mother, investigation of pilot generators with different elution mode, building a prototype generator, development and investigation of post-processing of the generator eluate, its concentration and further purification, the labeling chemistry under different conditions, in vitro and in vivo studies of labeled compounds and, finally, in vivo imaging experiments are described.