Follicle development and luteal cell morphology altered by phosphodiesterase-5 inhibitor

Vardenafil citrate is a potent vasodilator used in the treatment of patients with erectile dysfunction. Its mechanism of action is based on the selective inhibition of phosphodiesterase-5 (PDE5), specific to guanosine 3′,5′-cyclic monophosphate (cGMP). Recently, chronic treatment with Vardenafil has been successfully used in cases of pulmonary hypertension and, despite being used in high doses for long periods, little is known about its effects on other systems. In the present study, female mice were treated daily with 5 mg/kg Vardenafil for 4 weeks, after which the ovaries were collected for morphological analyses and sera were collected for biochemical assays. This study found that treatment with Vardenafil decreased HDL serum levels and the number of antral follicles as well as induced lesser lipid content in luteal cells, suggesting that high levels of cGMP may affect follicle development.     

Selection of stabilizing additive for lipase immobilization on controlled pore silica by factorial design

Candida rugosa lipase was covalently immobilized on silanized controlled poresilica (CPS) previously activated with glutaraldehyde in the presence of several additives to improve the performance of the immobilized from in long-term operation. Proteins (albumin and lecithin) and organic molecules (β-cyclodextrin and polyethylene glycol [PEG]-1500) were added during the immobilization procedure, and their effects are reported and compared to the behavior of the immobilized biocatalyst in the absence (lacking) of additive. The selection of the most efficient additive at different lipase loadings (150–450 U/g of dry support) was performed by experimental design. Two 2²full factorial designs with two repetitions at the center point were employed to evaluate the immobilization yield. A better, stabilizing effect was found when small amounts of albumin or PEG-1500, were added simul-taneou sly to the lipase on to the support. The catalytic activity had a maximum (193 U/mg) for lipase loading of 150 U/g of dry support using PEG-1500 as the stabilizing additive. This immobilized system was used to perform esterification reactions under repeated batch cycles (for the synthesis of butyl butyrate as a model). The half-life of the lipase immobilized on CPS in the presence of PEG-150 was found to increase fivefold compared with the control (immobilized lipase on CPS without additive).     

Nodal solutions for singularly perturbed equations with critical exponential growth

The existence and concentration behavior of nodal solutions are established for the equation −?²Δu+V(z)u=f(u) in Ω, where Ω is a domain in R², not necessarily bounded, V is a positive Hölder continuous function and f∈C¹ is an odd function having critical exponential growth.     

Generation of amorphous surface layers in LiNbO3 by ion-beam irradiation: thresholding and boundary propagation

The refractive-index profiles induced by high-energy (5 MeV, 7.5 MeV) silicon irradiation in LiNbO₃ have been systematically determined as a function of ion fluence in the range 10¹³–10¹⁵ cm^-2. At variance with irradiations at lower energies, an optically isotropic (‘amorphous’) homogeneous surface layer is generated whose thickness increases with fluence. These results have been associated with an electronic excitation mechanism. They are discussed in relation to the well-documented phenomenon of latent (amorphous) track generation under ion irradiation, requiring a threshold value S_e,th for the electronic stopping power S_e. Our optical data have yielded a value of ≈5 keV/nm for such a threshold, within the range reported by independent single-track measurements. The propagation of the amorphous boundary into the crystal during irradiation indicates that the threshold value decreases on increasing the fluence. Complementary Rutherford backscattering–channeling and micro-Raman (on samples irradiated at 30 MeV) experiments have been performed to monitor the induced structural changes. PACS 61.80.-x; 61.80.Az; 61.80.Jh     

An eigenvector‐based linear reconstruction scheme for the shallow‐water equations on two‐dimensional unstructured meshes

This paper presents a new approach to MUSCL reconstruction for solving the shallow‐water equations on two‐dimensional unstructured meshes. The approach takes advantage of the particular structure of the shallow‐water equations. Indeed, their hyperbolic nature allows the flow variables to be expressed as a linear combination of the eigenvectors of the system. The particularity of the shallow‐water equations is that the coefficients of this combination only depend upon the water depth. Reconstructing only the water depth with second‐order accuracy and using only a first‐order reconstruction for the flow velocity proves to be as accurate as the classical MUSCL approach. The method also appears to be more robust in cases with very strong depth gradients such as the propagation of a wave on a dry bed. Since only one reconstruction is needed (against three reconstructions in the MUSCL approach) the EVR method is shown to be 1.4–5 times as fast as the classical MUSCL scheme, depending on the computational application. Copyright © 2006 John Wiley & Sons, Ltd.     

Micro‐EDXRF investigation of Chalcolithic gold ornaments from Portuguese Estremadura

Chalcolithic gold artefacts assigned to the Bell Beaker Culture in Portuguese Estremadura were analysed by micro‐energy dispersive X‐ray fluorescence spectrometry. These high‐status jewels comprise beads of tubular, spiral and double‐conical type, a spiral ring and a wire fragment. The collection is mainly composed of gold with 8.7–16.3 wt% Ag and <0.04 wt% Cu. Additionally, there is a typologically uncommon double‐conical bead showing a lower Ag content (6.7 wt%). The relative intensity of the Ag‐Kα and Ag‐Lα X‐rays from artefacts established the existence of a surface layer depleted in silver, while the reasonable effective penetration depth of the Ag‐Kα (about 25–30 μm) provided suitable results for such high fineness gold alloys. A uniform Au–Ag composition at the joint indicates that the double‐conical bead was made by joining two sheets without solder. Overall, the collection shows a composition that is similar to known Chalcolithic gold in Portuguese Estremadura but different from coeval gold in Southwestern Iberian Peninsula. The distinct compositional pattern of Chalcolithic gold in Portuguese Estremadura seems to be inconsistent with the natural variability of silver content in alluvial deposits of gold in Iberian Peninsula, thus suggesting a continuous use of particular sources and limited exchange of nuggets and jewels with the neighbouring region. Copyright © 2017 John Wiley & Sons, Ltd.     

Characterization of oxide layers formed on electrochemically treated Ti by using soft X-ray absorption measurements

The oxide layers of electrolytic oxidized titanium (Ti) were characterized using Ti L_2,3 and O K edge X-ray absorption. The spectra show that the structure of the oxide layers that are formed during a 1 min treatment are dependent on the concentration of the electrolyte (H₂SO₄ or Na₂SO₄) with which the Ti surface was treated, and also on the magnitude of the potential that was applied during the anodic oxidation process (100 V or 150 V). It is found that a potential of 150 V and an electrolyte concentration of 0.5 M or 1.0 M produces a layer of TiO₂ having rutile crystal structure.     

Simultaneous Deconvolution of Molecular Weight Distribution and Chemical Composition Distribution of Ethylene/1-Olefin Copolymers Synthesized with Multiple-Site-Type Catalytic Systems

Summary: Ethylene/1-olefin copolymers synthesized with multiple-site-type catalytic systems typically exhibit broad molecular weight distribution (MWD) and chemical composition distribution (CCD). These microstrucral characteristics can be described by the presence of several active site types, each of which produces chains with distinct chain microstructures. In this work, a new approach to identify the number of active site types and chain microstructures produced on each active site type was developed based on simultaneous deconvolution of the bivariate MWD/CCD information. Chain microstructures produced on each active site type are assumed to follow Stockmayer's bivariate distribution. The proposed approach was validated with simulated data of model ethylene/1-butene and ethylene/1-octene copolymers.     

Simulation of Crystallization Analysis Fractionation (Crystaf) of Linear Olefin Block Copolymers

Summary: Linear olefin block copolymers (OBCs) have microstructures that are unique among polyolefins and exhibit properties that are different from those of other polyolefin elastomers. Characterizing their chain microstructures is a challenging task, as conventional characterization techniques cannot probe directly block length distribution or composition. In this work, we used a Monte Carlo model to predict the microstructure details of OBCs and a modified version of the Crystaf model previously developed in our groups to describe theoretical Crystaf profiles for model OBCs. This model can be used as a tool to interpret Crystaf results of these interesting new polyolefins and to relate them to OBC microstructures. Effects of polymerization parameters on OBC microstructure and Crystaf profiles were also discussed.     

CRYSTAF Analysis of Polyethylene Synthesized with Phillips Catalyst

Crystallization analysis fractionation (CRYSTAF) was used for the first time to investigate the solution crystallization behavior of ethylene homopolymers and copolymers made with Phillips CrO_x/SiO₂ catalyst. Interestingly, the crystallization peak temperatures (T_p) of copolymers of ethylene and cyclopentene increased with increasing cyclopentene molar fraction in the copolymer. Comparing two factors (short chain branches (SCBs) and cyclopentene incorporation), decreasing SCB frequency is proposed as the dominant factor to explain the increase of crystallization peak temperatures with increasing cyclopentene incorporation. In addition, SCB frequency and molecular weight might be the two significant factors determining the crystallization temperature of polyethylene made with Phillips CrO_x/SiO₂ catalyst with different cocatalysts (triethylaluminum and diethylaluminum ethoxide).