PCFDT: An accurate and friendly photonic crystal fiber design tool

This paper presents PCFDT, which is an accurate and friendly photonic crystal fiber design tool based on full-vectorial finite element method. Photonic crystal fibers based on circular and non-circular microstructured holes, and on different propagation mechanisms have been analyzed. Comparisons with other numerical methods and experimental results have shown excellent agreement. The design tool validation includes experimental results of hybrid photonic crystal fibers, proposed by us, which made possible for the first time light be simultaneously confined and manipulated by two propagation mechanism, total internal reflection and photonic bandgap effect.     

Effective Critical Micellar Concentration of a Zwitterionic Detergent: A Fluorimetric Study on <Emphasis Type="BoldItalic">n</Emphasis>-Dodecyl Phosphocholine

We have investigated the effect of ionic strength on the aggregation behavior of n-dodecyl phosphocholine. On the basis of the classical Corrin–Harkins relation, the critical micellar concentration of this detergent decreases with a biphasic trend on lithium chloride addition. It is nearly constant below 150 mM salt, with a mean value of 0.91 mM, whereas it undergoes a dramatic 80-fold decrease in 7 M LiCl. Such a drop in the critical micellar concentration could be explained by the effect of salting out and the implication of phosphocholine head groups on the organization of surrounding water. Knowledge of the effective critical micellar concentration of n-dodecyl phosphocholine could be useful in the purification of membrane proteins in non-denaturing conditions.     

Quantification of Protein “Biomarkers” in Wheat-Based Food Systems: Dealing with Process-Related Issues

Selected food proteins may represent suitable markers for assessing either the presence/absence of specific food ingredients or the type and intensity of food processes. A fundamental step in the quantification of any protein marker is choosing a proper protocol for solubilizing the protein of interest. This step is particularly critical in the case of solid foods and when the protein analyte is prone to undergo intermolecular disulfide exchange reactions with itself or with other protein components in the system as a consequence of process-induced unfolding. In this frame, gluten-based systems represent matrices where a protein network is present and the biomarker proteins may be either linked to other components of the network or trapped into the network itself. The protein biomarkers considered here were wheat gluten toxic sequences for coeliac (QQPFP, R5), wheat germ agglutinin (WGA), and chicken egg ovalbumin (OVA). These proteins were considered here in the frame of three different cases dealing with processes different in nature and severity. Results from individual cases are commented as for: (1) the molecular basis of the observed behavior of the protein; (2) the design of procedure aimed at improving the recovery of the protein biomarker in a form suitable for reliable identification and quantification; (3) a critical analysis of the difficulties associated with the plain transfer of an analytical protocol from one product/process to another. Proper respect for the indications provided by the studies exemplified in this study may prevent coarse errors in assays and vane attempts at estimating the efficacy of a given treatment under a given set of conditions. The cases presented here also indicate that recovery of a protein analyte often does not depend in a linear fashion on the intensity of the applied treatment, so that caution must be exerted when attributing predictive value to the results of a particular study.     

Essential Oil from Eucalyptus globulus (Labill.) Activates Complement Receptor-Mediated Phagocytosis and Stimulates Podosome Formation in Human Monocyte-Derived Macrophages

Eucalyptus essential oil and its major constituent eucalyptol are extensively employed in the cosmetic, food, and pharmaceutical industries and their clinical use has recently expanded worldwide as an adjuvant in the treatment of infective and inflammatory diseases. We previously demonstrated that essential oil from Eucalyptus globulus (Labill.) (EO) stimulates in vitro the phagocytic activity of human monocyte-derived macrophages and counteracts the myelotoxicity induced by the chemotherapeutic 5-fluorouracil in immunocompetent rats. Here we characterize some mechanistic aspects underlying the immunostimulatory ability exerted by EO on macrophages. The internalization of fluorescent beads, fluorescent zymosan BioParticles, or apoptotic cancer cells was evaluated by confocal microscopy. Pro-inflammatory cytokine and chemokine release was determined by flow cytometry using the BD cytometric bead array. Receptor involvement in EO-stimulated phagocytosis was assessed using complement- or IgG-opsonized zymosan particles. The localization and expression of podosome components was analyzed by confocal microscopy and western blot. The main results demonstrated that: EO-induced activation of a macrophage is ascribable to its major component eucalyptol, as recently demonstrated for other cells of innate immunity; EO implements pathogen internalization and clearance by stimulating the complement receptor-mediated phagocytosis; EO stimulates podosome formation and increases the expression of podosome components. These results confirm that EO extract is a potent activator of innate cell-mediated immunity and thereby increase the scientific evidence supporting an additional property of this plant extract besides the known antiseptic and anti-inflammatory properties.     

ESCA surface study of polystyrene photodegradation accelerated by 2-(2-methoxy-5-methylphenyl)-2H-benzotriazole

The accelerated ageing of polystyrene by means of 2-(2-methoxy-5-methylphenyl)-2H-benzotriazole, under conditions reproducing the outdoor environment, was studied. The results show that this benzotriazole derivative appreciably accelerates the rate of photodegradation at the surface of polystyrene.     

C2‐Symmetric Zirconocenes in the Polymerization of Conjugated Diolefins

C₂‐symmetric zirconocenes activated by methylaluminoxane were utilized as catalysts in the polymerization of 1,3‐diolefins. The results indicate that the most crowded catalytic precursor rac[CH₂(3‐tert‐butyl‐1‐indenyl)₂]ZrCl₂ ( 1 ) is also the most active one, giving 1,4‐polymerization of 1,3‐butadiene and (Z)‐1,3‐pentadiene and 1,2‐polymerization of (E)‐1,3‐pentadiene and 4‐methyl‐1,3‐pentadiene. Probably, the different behavior of 1 with respect to other C₂‐symmetric zirconocenes utilized is due to the different stability of the bond between the last inserted monomer unit and the metal, as well as to the coordination of incoming monomer.     

New Ni(II) based catalysts active in the polymerization of olefins

Polymerization of ethylene in the presence of Cp₂Ni (Cp: cyclopentadienyl) and methylaluminoxane affords polyethylene of high molecular weight and with high melting point. The same catalyst is active in the polymerization of styrene and 1,3-butadiene to give partially isotactic polystyrene and 1,4-cis-polybutadiene, respectively.