Action of soil microorganisms on PCL and PHBV blend and films

Poly(hydroxybutyrate-co-valerate) (PHBV) and poly(epsilon-caprolactone) (PCL) PCL/PHBV (4:1) blend films were prepared by melt-pressing. The biodegradation of the films in response to burial in soil for 30 days was investigated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetry (TG). The PHBV film was the most susceptible to microbial attack, since it was rapidly biodegraded via surface erosion in 15 days and completely degraded in 30 days. The PCL film also degraded but more slowly than PHBV. The degradation of the PCL/PHBV blend occurred in the PHBV phase, inducing changes in the PCL phases (interphase) and resulting in an increase of its crystalline fraction.

Structural and morphological changes in Poly(caprolactone)/poly(vinyl chloride) blends caused by UV irradiation

Films made from a blend of poly(epsilon-caprolactone) and poly(vinyl chloride) (PCL/PVC) retained high crystallinity in a segregated PCL phase. Structural and morphological changes produced when the films were exposed to high potency ultraviolet (UV) irradiation for 10 h were measured by UV-Vis spectroscopy (UV-Vis), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy (SEM). They were different to those observed with homopolymer PCL and PVC films treated under the same conditions. The FTIR spectra of the PCL/PVC blend suggest that blending decreased the susceptibility of the PCL to crystallize when irradiated. Similarly, although scanning electron micrographs of PCL showed evidence of growth of crystalline domains, particularly after UV irradiation, the images of PCL/PVC were fairly featureless. It is apparent that the degradation behavior is strongly influenced by the interaction of the two polymers in the amorphous phase.

Carbon dioxide formation during initial stages of photodegradation of poly(ethyleneterephthalate) (PET) films

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

Biodegradation of a polylactic acid/polyvinyl chloride blend in soil

This study investigated the microbial action in soil on poly(L-lactic acid) (PLLA) and polyvinyl chloride (PVC) films and a PLLA/PVC 7 : 3 blend, using Fourier transform infrared spectroscopy (FTIR), contact angle and scanning electron microscopy (SEM). The films (50 mu m) were obtained from the evaporation of dichloromethane solutions and buried in soil columns, in controlled conditions, for 120 days. The results showed that the surface of the PLLA films and blend became 18 and 31% more hydrophilic, respectively. The morphology of the films also changed after 120 days of microbial treatment, particularly that of the PLLA phase in the blend, confirmed by structural and conformational changes in the FTIR CO region at 12001000 cm1 and an increase in the relative intensity of the band at 1773 cm1, which was attributed to C O group vibration due to a rotational isomer in the interlamellar region (semi-ordered region). Besides the biotreated PVC presented changes in the C-Cl band at 738 cm1, due to the presence of some PVC conformational isomer. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

A systematic study of transfection efficiency and cytotoxicity in HeLa cells using iron oxide nanoparticles prepared with organic and inorganic bases

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

Synergistic effect in the catalytic activity of lipase Rhizomucor miehei immobilized on zeolites for the production of biodiesel

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

Classification of normal swallowing and oropharyngeal dysphagia using wavelet

Oropharyngeal dysphagia is characterized by any alteration in swallowing dynamics which may lead to malnutrition and aspiration pneumonia. Early diagnosis is crucial for the prognosis of patients with dysphagia, and the best method for swallowing dynamics assessment is swallowing videofluoroscopy, an exam performed with X-rays. Because it exposes patients to radiation, videofluoroscopy should not be performed frequently nor should it be prolonged. This study presents a non-invasive method for the pre-diagnosis of dysphagia based on the analysis of the swallowing acoustics, where the discrete wavelet transform plays an important role to increase sensitivity and specificity in the identification of dysphagic patients. (C) 2008 Elsevier B.V. All rights reserved.

Physicochemical characterization of collagen fibers and collagen powder for self-composite film production

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

Morphological and Structural Characteristics of Zein Biofilms with Added Xanthan Gum

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

The interaction between heparin and Lys49 phospholipase A(2) reveals the natural binding of heparin on the enzyme

We have studied at a molecular level the interaction of heparins on bothropstoxin-1 (BthTx-1), a phospholipase A(2) toxin. The protein was monitored using gel filtration chromatography, dynamic light scattering (DLS), circular dichroism (CD), attenuated total reflectance Fourier transform infrared (ATR-FTIR) and intrinsic tryptophan fluorescence emission (ITFE) spectroscopy. The elution profile of the protein presents a displacement of the protein peak to larger complexes when interacting with higher concentration of heparin. The DLS results shows two R-h at a molar ratio of 1, one to the distribution of the protein and the second for the action of heparin on BthTx-I structures, and a large distribution with the increase of protein. The interaction is accompanied by significant changes in the CD spectra, showing two common features: a decrease in signal at 208 nm (3 and 6 kDa heparins) and an isodichroic point near 226 nm (3 kDa heparin). FTIR spectra indicate that only a few amino acid residues are involved in this interaction. Alterations in the ITFE by binding heparins suggest that the initial binding occurs on the ventral face of BthTx-1. Together, these results add an experimental and structural basis on the action mechanism of the heparins over the phospholipases A(2) and provide a molecular model to elucidate the interaction of the enzyme-heparin complex at a molecular level. (c) 2005 Elsevier B.V. All rights reserved.

A micelle nucleation model for the interaction of dodecyl sulphate with Lys49-phospholipases A(2)

Bothropstoxin-I (BthTx-I) is a Lys49-PLA(2) from the venom of Bothrops jararacussu that lacks detectable catalytic activity, yet causes rapid Ca2+-independent membrane damage. With the aim of understanding the interaction between BthTx-I and amphiphilic molecules, we have studied the interaction of sodium dodecyl sulphate (SDS) with the protein. Circular dichroism and attenuated total reflection Fourier-transform infrared spectra of BthTx-I reveal changes in the alpha-helical organization of the protein at an SDS/BthTx-I molar ratio of 20-25. At SDS/BthTx-I ratios of 40-45 the alpha-helices return to a native-like conformation, although fluorescence emission anisotropy measurements of 2-amino-N-hexadecyl-benzamide (AHBA) demonstrate that the total SDS is below the critical micelle concentration when this transition occurs. These results may be interpreted as the result of SDS accumulation by the BthTx-I homodimer and the formation of a pre-micelle SDS/BthTx-I complex, which may subsequently be released from the protein surface as a free micelle. Similar changes in the alpha-helical organization of BthTx-I were observed in the presence of dipalmitoylphosphatidylcholine liposomes, suggesting that protein structure transitions coupled to organization changes of bound amphiphiles may play a role in the Ca2+-independent membrane damage by Lys49-PLA(2)s. (c) 2006 Elsevier B.V. All rights reserved.

Development of a simple and versatile ultrafiltration system for the fractionation of aquatic humic substances

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

Surface characterization of feldspathic ceramic using ATR FT-IR and ellipsometry after various silanization protocols

Objectives. This study characterized the feldspathic ceramic surfaces after various silanization protocols.Methods. Ceramic bars (2 mm x 4 mm x 10 mm) (N = 18) of feldpathic ceramic (VM7, VITA Zahnfabrik) were manufactured and finished. Before silane application, the specimens were ultrasonically cleaned in distilled water for 10 min. The ceramic specimens were randomly divided into nine groups (N = 2 per group) and were treated with different silane protocols. MPS silane (ESPE-Sil, 3M ESPE) was applied to all specimens and left to react at 20 degrees C for 2 min (G20). After drying, the specimens were subjected to heat treatment in an oven at 38 degrees C (G38), 79 degrees C (G79) or 100 degrees C (G100) for 1 min. Half of the specimens of each group were rinsed with water at 80 degrees C for 15 s (G20B, G38B, G79B, G100B). The control group (GC) received no silane. Attenuated total reflection infrared Fourier transform analysis (ATR FT-IR) was performed using a spectrometer. Thickness of silane layer was measured using a spectroscopic ellip-someter working in the lambda = 632.8 nm (He-Ne laser) at 70 degrees incidence angle. Surface roughness was evaluated using an optical profilometer. Specimens were further analyzed under the Scanning Electron Microscopy (SEM) to observe the topographic patterns.Results. ATR FT-IR analysis showed changes in Si-O peaks with enlarged bands around 940 cm(-1). Ellipsometry measurements showed that all post-heat treatment actions reduced the silane film thickness (30.8-33.5 nm) compared to G20 (40 nm). The groups submitted to rinsing in hot water (B groups) showed thinner silane films (9.8-14.4 nm) than those of their corresponding groups (without washing) (30.8-40 nm). Profilometer analysis showed that heat treatments (Ra approximate to 0.10-0.19 mu m; Rq approximate to 0.15-0.26 mu m) provided a smoother surface than the control group (Ra approximate to 0.48 mu m; Rq approximate to 0.65 mu m). Similar patterns were also observed in SEM images.Significance. Heat treatment after MPS silane application improved the silane layer network. Rinsing with boiling water eliminated the outmost unreacted regions of the silane yielding to thinner film thicknesses. (C) 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

QUASIDISTRIBUTIONS and COHERENT STATES FOR FINITE-DIMENSIONAL QUANTUM SYSTEMS

In recent years, an approach to discrete quantum phase spaces which comprehends all the main quasiprobability distributions known has been developed. It is the research that started with the pioneering work of Galetti and Piza, where the idea of operator bases constructed of discrete Fourier transforms of unitary displacement operators was first introduced. Subsequently, the discrete coherent states were introduced, and finally, the s-parametrized distributions, that include the Wigner, Husimi, and Glauber-Sudarshan distribution functions as particular cases. In the present work, we adapt its formulation to encompass some additional discrete symmetries, achieving an elegant yet physically sound formalism.

Structural modifications in stretch-induced crystallization in PVDF films as measured by small-angle X-ray scattering

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