Comparative Response of Rams and Bulls to Long-Term Treatment with Gonadotropin-Releasing Hormone Analogs

The objective was to compare the relative response between rams and bulls in characteristics of LH, FSH and testosterone (T) secretion, during and after long-term treatment with GnRH analogs. Animals were treated with GnRH agonist, GnRH antagonist, or vehicle (Control) for 28 days. Serial blood samples were collected on day 21 of treatment, and at several intervals after treatment. Injections of natural sequence GnRH were used to evaluate the capacity of the pituitary to release gonadotropins during and after treatment. Treatment with GnRH agonist increased basal LH and T concentrations in both rams and bulls, with a greater relative increase in bulls. Endogenous LH pulses and LH release after administration of GnRH were suppressed during treatment with GnRH agonist. Treatment with GnRH antagonist decreased mean hormone concentrations, LH and T pulse frequency, and the release of LH and T after exogenous GnRH, with greater relative effects in bulls. Rams previously treated with antagonist had a greater release of LH after administration of GnRH compared with control rams, while rams previously treated with agonist showed a reduced LH response. Bulls previously treated with agonist had reduced FSH concentrations and LH pulse amplitudes compared with control bulls while bulls previously treated with antagonist had greater T concentrations and pulse frequency. The present study was the first direct comparison between domestic species of the response in males to treatment with GnRH analogs. The findings demonstrated that differences do occur between rams and bulls in LH, FSH and testosterone secretion during and after treatment. Also, the consequences of treatment with either GnRH analog can persist for a considerable time after discontinuation of treatment

Phononic Band Structure by Calculating Effective Parameters of One-Dimensional Metamaterials

Using a theory of homogenization that consists in the discretization of the inclusion of a binary phononic crystal in small volumes, in which the material parameters can be expanded in Fourier series, we have determined the dependence of the effective elastic parameters as a function of the frequency. In particular, the frequency dependence of all the elements that constitute the effective tensors of stiffness (moduli of elasticity) and density was analyzed for a 1D phononic crystal conformed of materials whose main characteristic is the high contrast between their elastic properties. In this dynamic case of homogenization, it was found that the effective parameters can reproduce the exact dispersion relations for the acoustic modes that propagate along the periodicity direction of the crystal. Particularly, in the second pass band (high-frequency branch) corresponding to the transverse vibrational modes, the homogenized elastic phononic crystal exhibits a metamaterial behavior because the effective C44-component (shear modulus) and dynamic mass density were found to be both negative. It is noteworthy that the study derived from this homogenization technique can lead to design of double negative metamaterial systems for potential applications

Study of a Lead-Free Perovskite Solar Cell Using CZTS as HTL to Achieve a 20% PCE by SCAPS-1D Simulation

In this paper, a n-i-p planar heterojunction simulation of Sn-based iodide perovskite solar cell (PSC) is proposed. The solar cell structure consists of a Fluorine-doped tin oxide (FTO) substrate on which titanium oxide (TiO2) is placed; this material will act as an electron transporting layer (ETL); then, we have the tin perovskite CH3NH3SnI3 (MASnI3) which is the absorber layer and next a copper zinc and tin sulfide (CZTS) that will have the function of a hole transporting layer (HTL). This material is used due to its simple synthesis process and band tuning, in addition to presenting good electrical properties and stability; it is also a low-cost and non-toxic inorganic material. Finally, gold (Au) is placed as a back contact. The lead-free perovskite solar cell was simulated using a Solar Cell Capacitance Simulator (SCAPS-1D). The simulations were performed under AM 1.5G light illumination and focused on getting the best efficiency of the solar cell proposed. The thickness of MASnI3 and CZTS, band gap of CZTS, operating temperature in the range between 250 K and 350 K, acceptor concentration and defect density of absorber layer were the parameters optimized in the solar cell device. The simulation results indicate that absorber thicknesses of 500 nm and 300 nm for CZTS are appropriate for the solar cell. Further, when optimum values of the acceptor density (NA) and defect density (Nt), 1016 cm−3 and 1014 cm−3, respectively, were used, the best electrical values were obtained: Jsc of 31.66 mA/cm2, Voc of 0.96 V, FF of 67% and PCE of 20.28%. Due to the enhanced performance parameters, the structure of the device could be used in applications for a solar energy harvesting system

Discretization Approach for the Homogenization of Three-Dimensional Solid-Solid Phononic Crystals in the Quasi-Static Limit: Density and Elastic Moduli

With the application of a homogenization theory, based on the Fourier formalism (which provides efficient and exact formulas by which to determine all the components of the effective stiffness and mass density tensors, valid in the regime of large wavelengths), a new approach to calculate the effective quasi-static response in three-dimensional solid-solid phononic crystals is reported. The formulas derived in this work for calculating the effective elastic parameters show a dependence, in terms of summations over the vectors, of the reciprocal lattice by the discretization of the volume of the inclusion in small parts (e.g., small cubes), to obtain a system of equations from which we define the effective response. In particular, we present the numerical results calculated for several cubic lattices with solid constituents and different shapes of inclusions in the unit cell versus the filling fraction, as well as for fixed values of it. By this means, we analyzed the effect of the type of Bravais lattice of the materials, and the geometry of the inclusions that constitute the three-dimensional phononic array, on the resulting effective anisotropy. Finally, our theory confirms other well-known results with previous homogenization theories as a particular case study. In this regard, the examples and results shown here can be useful for the design of metamaterials with predetermined elastic properties

Puberdade e maturidade sexual em touros jovens da raça Simental, criados sob regime extensivo em clima tropical Puberty and sexual maturity in young Simmental bulls, raised under pasture conditions in a tropical climate

Objetivou-se determinar a idade à puberdade e maturidade sexual e sua relação com peso corporal e mensurações testiculares em tourinhos da raça Simental criados sob regime extensivo em clima tropical. Utilizaram-se 44 tourinhos com 1 a 30 meses de idade. As mensurações corporais e testiculares foram feitas mensalmente e os ejaculados coletados quinzenalmente, a partir dos seis meses de idade, utilizando-se o método de eletroejaculação. Observou-se idade à puberdade aos 13,42 ± 3,02 meses e maturidade sexual aos 21,43 ± 6,6 meses de idade, com peso corporal e perímetro escrotal, respectivamente, de 324,2 ± 23,7 kg e 26,90 ± 1,41 cm para a puberdade e 360 ± 69,04 kg e 34,88 ± 3,9 cm para maturidade sexual. Este estudo revelou idade tardia para a cronologia dos eventos reprodutivos, com relação direta do tipo de manejo adotado.<br>The objective of this study was to determine the age at puberty and sexual maturity and its relationship with body weight and testicular measurements in Simmental young bulls raised under pasture conditions in a tropical climate. Forty-four young bulls at 1 to 30 months of age were used. Body and testicular measurements were made monthly and ejaculates collected fortnightly, from six months of age by using the method of electroejaculation. Age at puberty was 13.42 ± 3.02 months and sexual maturity was observed at 21.43 ± 6.6 months of age, with body weight and scrotal circumference of 324.2 ± 23.7 kg and 26.90 ± 1.41 cm for puberty and 360 ± 69.04 kg and 34.88 ± 3.9 cm to sexual maturity, respectively. This study found late age to the timing of reproductive events, with direct relation to the type of management adopted