Asymptotically almost periodic solutions for abstract neutral integro-differential equations

We study the existence of asymptotically almost periodic classical solutions for a class of abstract neutral integro-differential equation with unbounded delay. A concrete application to partial neutral integro-differential equations which arise in the study of heat conduction in fading memory material is considered.     

Smoluchowski’s equation: Rate of convergence of the Marcus-Lushnikov process

We derive a satisfying rate of convergence of the Marcus-Lushnikov process towards the solution to Smoluchowski’s coagulation equation. Our result applies to a class of homogeneous-like coagulation kernels with homogeneity degree ranging in (−∞,1]. It relies on the use of a Wasserstein-type distance, which has shown to be particularly well-adapted to coalescence phenomena. It was introduced and used in preceding works (Fournier and Laurençot (2006) [7]) and (Fournier and Löcherbach (2009) [8]).     

Hormonal therapy in the senescence: Prostatic microenvironment structure and adhesion molecules

Hormonal replacement has been utilized to minimize the harmful effects of hormonal imbalance in elderly men. The development and progression of prostatic diseases and their relation to hormone therapy is still unclear. Thus, the aim herewith was to characterize the structure and dystroglycan molecule (DGs) reactivities in the ventral prostatic lobe from elderly rats submitted to steroid hormone replacement. Male rats (Sprague-Dawley) were divided into one Young group and six senile groups. The Young group (YNG) (4 months old) received peanut oil (5mL/kg, s.c.). The senile rats (10 months old) were submitted to the following treatments: Senile group (SEN) (5mL/kg peanut oil, s.c.); Testosterone group (TEST) (5mg/kg testosterone cipionate, s.c.); Estrogen group (EST) (25μg/kg 17β-estradiol, s.c.); Castrated group (CAS) (surgical castration); Castrated-Testosterone (CT) (surgical castration and treatment similar to TEST group); and Castrated-Estrogen (CE) (surgical castration and treatment similar to EST group). After 30 days treatment, blood samples were collected for hormonal analysis and ventral prostate samples were processed for light and transmission electron microscopies, morphometrical analysis, immunohistochemistry and Western Blotting. The results showed decreased serum testosterone levels in the senescence and increased testosterone and estrogen plasmatic levels after hormone administration in the TEST and EST groups, respectively, highlighting the therapy efficiency. Hypertrophied stroma and inflammatory cells were verified in the SEN group. After hormone replacement in the senescence or following castration, atrophic epithelium, epithelial cells with clear cytoplasmic halo around the nucleus, microacini and maintenance of hypertrophied stroma were seen. Decreased DG levels were verified in the senescence. After hormonal therapy, increased protein levels of these molecules were observed, especially in those groups which received estradiol. Thus, the occurrence of inflammatory cells, stromal hypertrophy and the presence of cells with clear halo around the nucleus after hormonal therapy probably indicated prostatic paracrine signaling imbalance, suggesting a stromal reactive microenvironment favorable to the development of glandular lesions. However, the increase of DG levels characterized positive effect of steroid hormone replacement on the prostate in the senescence. Thus, it could be concluded that despite having positive effects on important molecules involved in the maintenance of epithelial-stromal interaction and glandular cytoarchitecture, such as DGs, hormonal therapy enhanced structural changes associated with senescence, probably due to increased hormonal imbalance between androgens and estrogens in the prostatic tissue.     

Bioelectroanalytical Determination of Rutin Based on bi‐Enzymatic Sensor Containing Iridium Nanoparticles in Ionic Liquid Phase Supported in Clay

A matrix comprising iridium nanoparticles and 1‐butyl‐3‐methylimidazolium tetrafluoroborate ionic liquid (Ir‐BMI.BF₄) supported in montmorillonite (MMT) was obtained through an efficient incorporation process. This modified clay matrix (Ir‐BMI.BF₄‐MMT) was used for the immobilization of the enzymes laccase (LAC) and polyphenol oxidase (PPO) and employed in the construction of a bi‐enzymatic biosensor for determination of rutin by square‐wave voltammetry. Under optimized conditions, the analytical curve showed a linear range for rutin concentrations from 9.17×10^?8 to 3.10×10^?6 mol L^?1 with a detection limit of 3.09×10^?8 mol L^?1. The method was successfully applied to the determination of rutin content in pharmaceutical samples.     

A DFT/TDDFT study of porphyrazines and phthalocyanine oxo‐titanium derivatives as potential dyes in solar cells

Density functional theory and time dependent density functional theory calculations at the level of LDA/BP86/TZ2P were performed systematically on several Ti(IV) complexes of porphyrazines and one phthalocyanine. We performed an analysis of the frontier molecular orbitals of the ground state electronic structures and also discuss in particular the good concordance of our results with the experimental data, which affords to predict the geometrical and optical properties of new complexes ( 3 , 4 , and 7 ). We also emphasize the characterization of the UV–vis absorption spectra and propose transitions that contribute to the Q and B bands. Some useful calculated properties in complexes 2 , 3 , and 7 , like: high light absorption in the visible region of the spectra, transitions involved in these bands with a determined direction, charge separation, bigger highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO‐LUMO) gaps than complexes 4 and 5 , and the energy of their LUMO orbitals (that are higher than the lowest energy level of the conduction band of the TiO₂) indicate that system complexes 2 , 3 , and 7 could act as light‐harvesting sensitizers for dye‐sensitized solar cells (DSCs). These proposals were made using a model of the previously experimentally known phthalocyanine, which was used as sensitizer in DSCs devices, comparing its electronic properties with the herein proposed sensitizers. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

A new optimization strategy for gaseous phase sampling by an internally cooled solid-phase microextraction technique

This study describes a new optimization strategy for internally cooled solid-phase microextraction based on a multivariate approach. The coating temperature was changed in an extraction while manipulating the extraction times to improve the extraction of compounds with different volatilities. Polycyclic aromatic hydrocarbons (PAHs) and phthalic acid esters (PEs) and adipate were used as model compounds in this study. The optimization strategy was in two steps: (1) multivariate optimization of extraction time and initial coating temperature and (2) multivariate optimization of total extraction time and the time required to cool the coating to a lower temperature as determined in step 1. The observed analytical response in relation to the coating temperature was found to be dependent on the analyte volatility and size. The optimized extraction condition for PEs was 23 min extraction while maintaining the coating at 140°C, followed by 7 min of cooling the coating at 10°C. For the PAHs the coating temperature was maintained at 60°C for the first 20 min and at 5°C in the last 20 min of extraction. Comparisons have been made between the proposed optimized conditions with the conventional internally cooled fiber approach and the results thoroughly discussed. The proposed optimization strategy was found to be more effective for all the analytes, especially for the semi-volatiles, compared to the conventional method.     

Determination of fluorine in tea using high-resolution molecular absorption spectrometry with electrothermal vaporization of the calcium mono-fluoride CaF

High-resolution continuum source molecular absorption of the calcium mono-fluoride molecule CaF in a graphite furnace has been used to determine fluorine in tea after acid digestion, alkaline solubilization and preparation of a conventional aqueous infusion. The strongest absorption ‘line’ of the CaF molecule is at 606.440 nm, which is part of the rotational fine structure of the X²Σ⁺ − A²Π electronic transition; it has a bond dissociation energy of 529 kJ mol⁻¹, which is comparable with other molecules used for fluorine determination. One advantage of using Ca as the molecule-forming reagent is that spectral interferences are extremely unlikely in the spectral range of its strongest absorption. Another advantage is that Ca acts both as molecule forming reagent and chemical modifier, so that no other reagent has to be added, making the method very simple. The only disadvantage is that Ca has a somewhat negative influence on the graphite tube lifetime. The limit of detection was found to be 0.16 mg L⁻¹ F, corresponding to 1.6 ng F absolute, and the calibration curve was linear in the range between 0.5 and 25 mg L⁻¹ with a correlation coefficient of R = 0.9994. The results obtained for a certified tea reference material were in agreement with the certified value on a 95% confidence level. There was also no difference between the results obtained after an acid digestion and an alkaline solubilization for 10 tea samples, based on a paired t-test. The values found in the 10 samples ranged between 42 μg g⁻¹ and 87 μg g⁻¹ F; the tea infusions contained between 21 μg g⁻¹ and 56 μg g⁻¹ F, with an extraction rate between 48% and 74%.     

Assessing the effect of oxygen and microbial inhibitors to optimize ferricyanide-mediated BOD assay

Methods for short-term BOD analysis (BOD_st) based on ferricyanide mediator reduction have succeeded in overcoming some problems associated with the standard BOD test analysis (BOD₅) such as long-term incubations (5 days), the need to dilute samples and low reproducibility. Here we present a bioassay where a Klebsiella pneumoniae environmental strain successfully reduces ferricyanide without de-aeration of the samples with linear BOD₅ ranges between 30 and 500 mg L⁻¹ or 30 and 200 mg L⁻¹, using glucose-glutamic acid solution (GGA) or OECD standards respectively. We further propose a new assay termination solution that allows higher reproducibility and standardization of the cell-based assay, employing formaldehyde (22.7 g L⁻¹) or other compounds in order to stop ferricyanide reduction without affecting the amperometric detection and therefore replace the centrifugation step normally used to stop microbial-driven reactions in ferricyanide-mediated bioassays. These improvements led to an accurate determination of real municipal wastewater samples.     

Reliable and efficient procedures for the conjugation of biomolecules through Huisgen azide-alkyne cycloadditions

The Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) has been established as a powerful coupling technology for the conjugation of proteins, nucleic acids, and polysaccharides. Nevertheless, several shortcomings related to the presence of Cu, mainly oxidative degradation by reactive oxygen species and sample contamination by Cu, have been pointed out. This Minireview discusses key aspects found in the development of the efficient and benign functionalization of biomacromolecules through CuAAC, as well as the Cu-free strain-promoted azide-alkyne cycloaddition (SPAAC).     

Irreversible electrostatic deposition of Prussian blue from colloidal solutions

Prussian blue (PB) can be deposited from colloidal solutions (5.4?×?10^?3?mol_PB?L^?1, 0.01?mol?L^?1 KNO₃) on glassy carbon, either by potential cycling or potentiostatically, provided that the deposition potential is more positive than ?0.2?V vs. Hg/Hg₂Cl₂. Depending on the deposition potential, the PB particles form either a single layer of Everitt??s salt, of PB, or multilayers of Berlin green. Also depending on the electrode potential, the deposition was accompanied by currents which were either only of capacitive nature, or represent the sum of capacitive and faradaic currents. The currents were always limited by the diffusion of the colloidal particles to the electrode surface, i.e., they obeyed the Cottrell equation. The PB layers were characterized by in situ atomic force microscopy.