Triclosan‐based antibacterial paper reinforced with nano‐montmorillonite: a model nanocomposite for the development of new active packaging

In this study, a suitable method is reported to produce reinforced antibacterial paper packaging using the antimicrobial triclosan (TC) and organically modified montmorillonite (OMMT) as “model” compounds. Direct incorporation of TC at a concentration of 1 wt% and OMMT at concentrations of 1, 4, 7, and 10 wt% into papers was performed via coating process, and the resulting materials were characterized by in vitro antimicrobial assays, thermogravimetric analysis, scanning electron microscopy, mechanical tests, and water vapor transmission rate determinations. It was demonstrated that the presence of 1% TC in the coated papers exhibited inhibitory effects against Staphylococcus aureus and Escherichia coli. It was also pointed out that increases of approximately 30% in the tensile strength of commercial paper are obtained by using the OMMT at a concentration of 1 wt%. Water barrier property and thermal stability of paper were also enhanced because of the coating process and the incorporation of OMMT. The results from this study demonstrate that OMMT has a great potential to be incorporated into coating formulations to obtain antibacterial‐coated papers with improved properties for various packaging applications. Copyright © 2011 John Wiley & Sons, Ltd.     

Direct evidence for As as a Zn-site impurity in ZnO

Arsenic has been reported in the literature as one of the few p-type dopants in the technologically promising II-VI semiconductor ZnO. However, there is an ongoing debate whether the p-type character is due to As simply replacing O atoms or to the formation of more complicated defect complexes, possibly involving As on Zn sites. We have determined the lattice location of implanted As in ZnO by means of conversion-electron emission channeling from radioactive (73)As. In contrast to what one might expect from its nature as a group V element, we find that As does not occupy substitutional O sites but in its large majority substitutional Zn sites. Arsenic in ZnO (and probably also in GaN) is thus an interesting example for an impurity in a semiconductor where the major impurity lattice site is determined by atomic size and electronegativity rather than its position in the periodic system.     

Synthesis, thermal treatment and characterization of cobalt ferrite-based nanocomposites

We have used time-differential perturbed angular correlation (PAC) spectroscopy with ¹⁸¹Ta-probes to study the electric field gradient at Zr-sites in synthetic zircon and hafnon between room temperature and 1,200°C. PAC spectra are similar to those obtained from naturally occurring zircons. In particular, a change in slope of the quadrupole coupling vs. temperature is observed in the synthetic zircon at the same temperature as seen in natural zircons from the Mud Tank carbonatite (Australia). The synthetic hafnon data also shows this feature but at somewhat higher temperature. Low-temperature PAC spectra of both synthetic zircon and hafnon have a clearly reduced anisotropy. We believe that the cause for this is a electronic defect, possibly created during the β-decay of the probe parent nucleus.     

Aromatic compounds produced by endophytic fungi isolated from red alga Asparagopsis taxiformis - Falkenbergia stage

Endophytic fungi were isolated from red alga Asparagopsis taxiformis - Falkenbergia stage, collected from the Brazilian coast, and were identified as Annulohypoxylon stygium (AT-03) and A. yungensis (AT-06) based on their macro/micromorphological and molecular features. Bioassay-guided fractionation of the EtOAc extract from laboratory cultures of both strains yielded known compounds pyrogallol from A. stygium, (3R)-scytalone and (3R,4R)-4-hydroxy-scytalone from A. yungensis. Pyrogallol was active against methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli strains. An inactive fraction from A. stygium afforded two additional compounds, (3R,4R)-3,4,5-trihydroxy-1-tetralone and tyrosol. Optically active compounds had their stereochemistry determined by circular dichroism (CD) spectroscopy.     

Interdiffusion at Sb/Ge interfaces induced in thin multilayer films by nanosecond laser irradiation

Thin films consisting of 3 or 4 Sb and Ge alternating layers are irradiated with single nanosecond laser pulses (12 ns, 193 nm). Real time reflectivity (RTR) measurements are performed during irradiation, and Rutherford backscattering spectrometry (RBS) is used to obtain the concentration depth profiles before and after irradiation. Interdiffusion of the elements takes place at the layer interfaces within the liquid phase. The reflectivity transients allow to determine the laser energy thresholds both to induce and to saturate the process being both thresholds dependent on the multilayer configuration. It is found that the energy threshold to initiate the process is lower when Sb is at the surface while the saturation is reached at lower energy densities in those configurations with thinner layers.     

Soliton solutions for quasilinear Schrödinger equations: The critical exponential case

Quasilinear elliptic equations in R²${\mathbb{R}}^2$ of second order with critical exponential growth are considered. By using a change of variable, the quasilinear equations are reduced to semilinear equations, whose respective associated functionals are well defined in H¹(R²)$H^1\left({\mathbb{R}}^2\right)$ and satisfy the geometric hypotheses of the mountain pass theorem. Using this fact, we obtain a Cerami sequence converging weakly to a solution v$v$. In the proof that v$v$ is nontrivial, the main tool is the concentration–compactness principle [P.L. Lions, The concentration compactness principle in the calculus of variations. The locally compact case. Part I and II, Ann. Inst. H. Poincaré Anal. Non. Linéaire 1 (1984) 109–145, 223–283] combined with test functions connected with optimal Trudinger–Moser inequality.     

Optical activity and damage recovery of erbium implanted strontium titanate

Single crystalline SrTiO 3 samples were implanted with Er ions of 150 v keV at room temperature with fluences of 5 ‐ 10 14 and 5 ‐ 10 15 . Annealing treatments were carried out both in reducing and oxidising atmospheres to recover the implantation damage. Infrared 1.54 v m Er 3+ luminescence between the two lowest spin-orbit levels 4 I 13/2 M 4 I 15/2 as well as emission from higher excited states 4 S 3/2 M 4 I 15/2 , 4 F 9/2 M 4 I 15/2 and 4 S 3/2 M 4 I 13/2 were observed in the implanted samples with highest fluence, annealed either in air or in vacuum. Multiple site location of Er 3+ ion is discussed and compared with RBS/C and emission channelling results that indicate that Er goes to Sr and Ti sites.     

Singular Hamiltonian elliptic systems with critical exponential growth in dimension two

We will focus on the existence of nontrivial solutions to the following Hamiltonian elliptic system where are numbers belonging to the interval [0, 2), V is a continuous potential bounded below on by a positive constant and the functions f and g possess exponential growth range established by Trudinger–Moser inequalities in Lorentz–Sobolev spaces. The proof involves linking theorem and a finite‐dimensional approximation.     

Efficiency and sustainability assessment for a group of farmers in the Brazilian Amazon

The aim of this paper is to use DEA models to evaluate sustainability in agriculture. Several variables are taken into account and the resulting efficiency is measured by comparison. The performance of family farms is analysed here (variables: farmed area, work force, and production). As agricultural sustainability depends on the maintenance of systems of production for long periods of time, the models were run for the years of 1986 and 2002. Tiered DEA models were used to group farmers in sustainability categories. Non-parametric regression models were used to identify the factors affecting the efficiency measurements. All the results indicate that the majority of the farmers increased their efficiency along the time. These improvements may support the existence of sustainability.     

Molecular Hybridization Strategy on the Design,Synthesis, and Structural Characterization of Ferrocene-N-acyl Hydrazones as Immunomodulatory Agents

Immunomodulatory agents are widely used for the treatment of immune-mediated diseases, but the range of side effects of the available drugs makes necessary the search for new immunomodulatory drugs. Here, we investigated the immunomodulatory activity of new ferrocenyl-N-acyl hydrazones derivatives (SintMed(141–156). The evaluated N-acyl hydrazones did not show cytotoxicity at the tested concentrations, presenting CC₅₀ values greater than 50 µM. In addition, all ferrocenyl-N-acyl hydrazones modulated nitrite production in immortalized macrophages, showing inhibition values between 14.4% and 74.2%. By presenting a better activity profile, the ferrocenyl-N-acyl hydrazones SintMed149 and SintMed150 also had their cytotoxicity and anti-inflammatory effect evaluated in cultures of peritoneal macrophages. The molecules were not cytotoxic at any of the concentrations tested in peritoneal macrophages and were able to significantly reduce (p < 0.05) the production of nitrite, TNF-α, and IL-1β. Interestingly, both molecules significantly reduced the production of IL-2 and IFN-γ in cultured splenocytes activated with concanavalin A. Moreover, SintMed150 did not show signs of acute toxicity in animals treated with 50 or 100 mg/kg. Finally, we observed that ferrocenyl-N-acyl hydrazone SintMed150 at 100 mg/kg reduced the migration of neutrophils (44.6%) in an acute peritonitis model and increased animal survival by 20% in an LPS-induced endotoxic shock model. These findings suggest that such compounds have therapeutic potential to be used to treat diseases of inflammatory origin.