Picrosirius-polarization staining method as an efficient histopathological tool for collagenolysis detectin in vesical prolapse lesions

The Picrosirius-polarization method has been indicated as a selective histochemical stain for collagen detection in tissue sections. This method can also be of value for studying collagen degradation given that, under polarized light, collagen displays birefringence due to its molecular order. The aim of this study is to highlight this staining method as an additional instrument for a rapid and excellent confirmatory diagnosis of the presence of collagenolysis in connective tissue in the vaginal wall with vesical prolapse lesion, in tissue sections. Dramatic changes in collagen morphology were found in vaginal mucosa in vesical prolapse disorder: they were weakly stained by Sirius red and under polarized light appeared as thin, pale (weakly birefringent), greenish, and with fibers more scattered, while the histoarchitecture of the organ showed a disrupted appearance. Thus, in the present study, we showed in vaginal mucosa in the vesicle prolapse that corroded collagenous framework appears as fragmentary and irregularly separated collagenous structures, that are weakly birefringent, corresponding to a molecular disorganization of these fibers caused by collagenolysis. (C) 2006 Elsevier Ltd. All rights reserved.

Fabrication and testing of a poly(vinylidene fluoride) (PVDF) microvalve for gas flow control

A microactuator made from poly(vinylidene fluoride) (PVDF), a piezoelectric polymer, was fabricated to control the gas flow rate through a glass micronozzle. The actuator was formed by gluing together two PVDF sheets with opposite polarization directions. The sheets were covered with thin conducting films on one side, that were then used as electrodes to apply an electric field to move the valve. The actuator has a rectangular shape, 3 mm x 6 mm. The device was incorporated with a micronozzle fabricated by a powder blasting technique. Upon applying a DC voltage across the actuator electrodes, one sheet expands while the other contracts, generating an opening motion. A voltage of +300 V DC was used to open the device by moving the actuator 30 mu m, and a voltage of -200 V DC was used to close the device by moving the actuator 20 mu m lower than the relaxed position. Flow measurements were performed in a low-pressure vacuum system, maintaining the microvalve inlet pressure constant at 266 Pa. Tests carried out with the actuator in the open position and with a pressure ratio (inlet pressure divided by outlet pressure) of 0.5, indicated a flow rate of 0.36 sccm. In the closed position, and with a pressure ratio of 0.2, a flow rate of 0.32 sccm was measured.

Cytochemistry and polarization microscopy of amphibian sperm cell nuclei presumed to differ in basic protein composition

The pattern of availability of free DNA phosphates, and the kind of DNA-protein complex arrangement, both induced by nuclear basic proteins, and the richness in arginine residues in these proteins were investigated cytochemically and cytophysically in spermatozoa of the South-American Hylidae species, Hyla fuscovaria and Hyla biobeba. The aim was to demonstrate differences at the level of sperm histones in two species of Hyla until recently considered to be congeneric. The results indicated differences in the spermatozoal nuclear basic proteins and DNA-protein complexes when the two species were compared. The spermatozoa of Hyla biobeba were assumed to be likely to contain a Bloch's ''type 3'' protein type (intermediate sperm basic protein), similarly to Hyla species of North and Central America. on the other hand, the data obtained for the spermatozoa of Hyla fuscovaria indicated that they contain a protamine or protamine-like protein, differing from Hyla biobeba and Hyla species of North and Central America. It is suggested that the differences reported here may be genus-specific, since Hyla fuscovaria has recently been reclassified as Scinax fuscovaria based on parameters other than sperm histone types. These findings are in agreement with the general view of a wide variability in sperm nuclear proteins in the Anura group.

THE VACUUM ENERGY OF QED WITH 4-FERMION INTERACTION

We consider quantum electrodynamics in the quenched approximation including a four-fermion interaction with coupling constant g. The effective potential at stationary points is computed as a function of the coupling constants alpha and g and an ultraviolet cutoff LAMBDA, showing a minimum of energy in the (alpha, g) plane for alpha = alpha(c) = pi/3 and g = infinity. When we go to the continuum limit (LAMBDA --> infinity), keeping finite the dynamical mass, the minimum of energy moves to (alpha = 0, g = 1), which correspond to a point where the theory is trivial.

Comments on spin operators and spin-polarization states of 2+1 fermions

In this brief article we discuss spin-polarization operators and spin-polarization states of 2 + 1 massive Dirac fermions and find a convenient representation by the help of 4-spinors for their description. We stress that in particular the use of such a representation allows us to introduce the conserved covariant spin operator in the 2 + 1 field theory. Another advantage of this representation is related to the pseudoclassical limit of the theory. Indeed, quantization of the pseudoclassical model of a spinning particle in 2 + 1 dimensions leads to the 4-spinor representation as the adequate realization of the operator algebra, where the corresponding operator of a first-class constraint, which cannot be gauged out by imposing the gauge condition, is just the covariant operator previously introduced in the quantum theory.

Effect of maltodextrin and arabic gum in water vapor sorption thermodynamic properties of vacuum dried pineapple pulp powder

Moisture equilibrium data of pineapple pulp (PP) powders with and without additives - 18% maltodextrin (MD) or 18% gum Arabic (GA) - were determined at 20, 30, 40 and 50 degrees C by using the static gravimetric method in a water activity range of 0.06-0.90. The obtained isotherms were sigmoid, typical type 111, and the Guggenhein-Anderson-de Boer (GAB) model was fitted to the experimental data of equilibrium moisture content versus water activity. Addition of additives was shown to affect the isotherms in such a way that, at the same water activity, samples PP + GA and PP + MD presented lower equilibrium moisture content and were not so affected by varying temperature. The net isosteric heats of sorption of pulp powders with additives were higher (less negative) than those of pineapple pulp powders, suggesting that there are more active polar sites in the product without addition of GA or MD. An empirical exponential relationship could describe the heat of sorption dependence on the material moisture content. (C) 2007 Elsevier Ltd. All rights reserved.

Evolution of CaCu3Ti4O12 varistor properties during heat treatment in vacuum

Calcium copper titanate (CaCu3Ti4O12) ceramic varistors were prepared by solid-state method. The samples were several times heat treated in vacuum and the evolution of electrical characteristics were monitored by current density versus electric field measurements and impedance spectroscopy. Repeated heat treatments in vacuum (900 degrees C for 1 h, 0.01 Torr) lead to a desorption of oxygen adsorbed at the grain boundaries and consequently to a degradation of the varistor properties. During further successive heat treatments some oxygen from the grain interior moves to the grain boundary thereby partially restoring the varistor properties. (c) 2006 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Crystal structure of a novel myotoxic Arg49 phospholipase A(2) homolog (zhaoermiatoxin) from Zhaoermia mangshanensis snake venom: Insights into Arg49 coordination and the role of Lys122 in the polarization of the C-terminus

The venom of Zhaoermia mangshanensis, encountered solely in Mt Mang in China's Hunan Province, exhibits coagulant, phosphodiesterase, L-amino acid oxidase, kallikrein, phospholipase A(2) and myotoxic activities. The catalytically inactive PLA(2) homolog referred to as zhaoermiatoxin is highly myotoxic and displays high myonecrotic and edema activities. Zhaoermiatoxin possesses a molecular weight of 13,972 Da, consists of 121 amino-acid residues crosslinked by seven disulfide bridges and shares high sequence homology with Lys49-PLA(2)s from the distantly related Asian pitvipers. However, zhaoermiatoxin possesses an arginine residue at position 49 instead of a lysine, thereby suggesting a secondary Lys49 -> Arg substitution which results in a catalytically inactive protein. We have determined the first crystal structure of zhaoermiatoxin, an Arg49-PLA(2), from Zhaoermia mangshanensis venom at 2.05 A resolution, which represents a novel member of phospholipase A(2) family. In this structure, unlike the Lys49 PLA(2)s, the C-terminus is well ordered and an unexpected non-polarized state of the putative calcium-binding loop due to the flip of Lys122 towards the bulk solvent is observed. The orientation of the Arg-49 side chain results in a similar binding mode to that observed in the Lys49 PLA(2)s; however, the guadinidium group is tri-coordinated by carbonyl oxygen atoms of the putative calcium-binding loop, whereas the N zeta atom of lysine is tetra-coordinated as a result of the different conformation adopted by the putative calcium-binding loop. (c) 2008 Elsevier Ltd. All rights reserved.

Contribution of an extrinsic mechanism for the electrical polarization in BiMn2O5 ceramics

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Kinetics of the polarization reversal process in a non-constant applied electric field and the generalized superposition principle

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Polarization in fermion scattering

The behaviour of the helicity of an initially left-handed beam of massive fermions first interacting with a Coulomb field and then with a charged scalar particle via a photon exchange is analysed. It is found that in both cases the massive fermions have their helicity flipped, while massless fermions seeem to be unaffected by the electromagnetic field as far as their helicity is concerned.

Discriminating new physics scenarios at the Next Linear Collider: The role of polarization

We explore the potential of the Next Linear Collider, operating in the e γ mode, to disentangle new physics scenarios in single W production. We study the effects related to the exchange of composite fermions in the reaction e γ→Wνe, and compare them with those arising from trilinear gauge boson anomalous couplings. We stress the role played by the initial state polarization to increase the reach of this machine and to discriminate the possible origin of the new phenomena.

Fixed points and vacuum energy of dynamically broken gauge theories

We show that if a gauge theory with dynamical symmetry breaking has nontrivial fixed points, they will correspond to extrema of the vacuum energy. This relationship provides a different method to determine fixed points.