Assessment of in vitro biofilm formation by Candida species isolates from vulvovaginal candidiasis and ultrastructural characteristics

Vulvovaginal candidiasis (VVC) is a very common cause of fungal infection that remains a significant problem worldwide, especially concerning its complex pathogenicity. Biofilm dynamics from vaginal isolates requires further investigation. Different assays, such as cell surface hydrophobicity (CSH), biofilm production, fungal metabolism by 2H-tetrazolium-5-carboxanilide (XTT) and phenazine methosulfate (PMS), scanning electron microscopy (SEM) and confocal scanning laser microscopy (CSLM) were used in order to determine the ability of five Candida species isolates from VVC patients to form in vitro biofilms and their ultrastructural characteristics. All yeasts demonstrated the ability to produce biofilm and showed viability up to 48 h after the completion of assay, confirmed by SEM and CSLM, but differences were observed between them. SEM and CSLM also revealed that all VVC isolates adhered only in blastoconidia form, except for Candida parapsilosis. Even though, only one isolate from each Candida species has been used, the results of high biofilm formation, metabolic activity and CSH showed by Candida albicans and C. parapsilosis, as well as by the ultrastructural characteristics, suggest that these species exhibit greater ability of adherence in relation to the others. Ours results support the theory that virulence potential is multifactorial and that other factors not evaluated in this study could be involved in the CVV physiopathogeny.     

New indole alkaloid from Peschiera affinis (Apocynaceae)

A new indole alkaloid of the pyridocarbazole type, named 6N-hydroxy-olivacine, and two known compounds, 2N-oxide-olivacine and olivacine, were isolated from roots of Peschiera affinis. The structures of the compounds were determined by spectroscopic {IR and extensive NMR (COSY, HMQC, HMBCand NOESY)} and EIMS analysis.     

Characterization of the end products of the hydrolysis of iron in aqueous solution

A characterization of the iron phases precipitated from aerated solutions of iron(II) sulfate heptahydrate was made using Mössbauer spectroscopy. The experimental conditions for the preparation of the samples were varied. The results are used to the further understanding of rust formation during atmospheric corrosion.     

A pivoting strategy for symmetric tridiagonal matrices

The LBL^T factorization of Bunch for solving linear systems involving a symmetric indefinite tridiagonal matrix T is a stable, efficient method. It computes a unit lower triangular matrix L and a block 1 × 1 and 2 × 2 matrix B such that T=LBL^T. Choosing the pivot size requires knowing a priori the largest element σ of T in magnitude. In some applications, it is required to factor T as it is formed without necessarily knowing σ. In this paper, we present a modification of the Bunch algorithm that can satisfy this requirement. We demonstrate that this modification exhibits the same bound on the growth factor as the Bunch algorithm and is likewise normwise backward stable. Copyright © 2005 John Wiley & Sons, Ltd.     

Poly(caprolactone triol) as plasticizer agent for cellulose acetate films: influence of the preparation procedure and plasticizer content on the physico‐chemical properties

The influence of the plasticizer content and film preparation procedure on the morphology, density, thermal and mechanical properties of cellulose acetate (CA) films plasticized with poly‐(caprolactone triol) (PCL‐T), were studied. Differential scanning calorimetry (DSC), thermal mechanical analysis (TMA), scanning electron microscopy (SEM), wide‐angle X‐ray diffraction (WAXD) and infrared spectroscopy (FT‐IR) techniques were used. The films were prepared by dry‐casting CA and CA/PCL‐T in acetone or acetone/water solutions, which produced transparent and opaque films, respectively. In contrast to the transparent films, which were dense, the opaque films presented a porous morphology. However, the presence of PCL‐T reduced the opaque film porosity, increasing, in consequence, its bulk density. The TMA results revealed that PCL‐T reduced the glass transition temperature more significantly in the transparent than in opaque films. Only the transparent CA/PCL‐T films presented a melting temperature, that reduced with higher concentrations of PCL‐T, suggesting a higher ordering (crystallinity) when the films were prepared in the absence of water, as observed from WAXD curves. The mechanical properties also showed that the transparent films were more soft and tough than the opaque films. In summary, PCL‐T was a good plasticizer agent for CA films due to the presence of hydrogen bonds between the components (FT‐IR spectra). The presence of water in the dry casting process has a significant effect mainly on film morphology and mechanical properties. Copyright © 2004 John Wiley & Sons, Ltd.     

Organic field-effect transistors from solution-deposited functionalized acenes with mobilities as high as 1 cm2/V x s

We present the device parameters for organic field-effect transistors fabricated from solution-deposited films of functionalized pentacene and anthradithiophenes. These materials are easily prepared in one or two steps from commercially available starting materials and are purified by simple recrystallization. For a solution-deposited film of functionalized pentacene, hole mobility of 0.17 cm2/V.s was measured. The functionalized anthradithiophenes showed behavior strongly dependent on the substituents, with hole mobilities as high as 1.0 cm2/V.s.     

Robust, soluble pentacene ethers

We report the synthesis and characterization of a series of alkoxy-substituted silylethynylated pentacene derivatives (R = CH(2)CH(2), CHCH, CH(2)). All three compounds are easily prepared, soluble in common organic solvents, and stable both as solids and in solution. Two of the derivatives possess significant pi-face interactions in the crystal. Values for lambda(max) for these new pentacene derivatives range from 621 to 674 nm, and oxidation potentials lie between 109 and 301 mV versus ferrocene.     

Spectroscopic characterization of polyaniline formed by using copper(II) in homogeneous and MCM-41 molecular sieve media

This work emphasizes the important role of the synthetic parameters in the structure of the polymeric material obtained in the aniline polymerization. The polymers formed by the oxidative polymerization of aniline by copper(II) ions in acidic aqueous solution, acetonitrile/water medium, and also copper(II) acetate complex encapsulated into MCM-41 molecular sieve were characterized by resonance Raman spectroscopy using three exciting laser lines and other techniques such as UV-vis, FTIR, and XANES (Nitrogen K edge). Additionally the products were investigated by thermogravimetric analysis and powder X-ray diffraction. When Cu(II) ions in acidic aqueous medium are used, emeraldine salt (ES-PANI) is formed through the usual head-to-tail polymerization mechanism, while in acetonitrile/water medium a polymer is observed having mainly phenazine-like rings, quinonediimine, and/or phenylenediamine segments in the chains, suggesting that a distinct mechanism is operating. The average molecular weights of the free polymers synthesized in water and in acetronile/water were, respectively, ca. 37 300 and 16 900 Da. The encapsulated polymer synthesized in Cu(II)-MCM-41 is a polymeric mixture of (i) ES-PANI and (ii) the polymer obtained when this metal cation was used as oxidant in acetonitrile/water medium. All the characterization data were compared to those ones obtained for standard free polyaniline and also for the encapsulated polymer into mesoporous MCM-41 formed by using persulfate in acidic aqueous medium as oxidant.     

Preparation of composite materials containing iron in a cross-linked resin host based on styrene and divinylbenzene

Iron composite materials based on styrene/divinylbenzene network hosts were produced using aqueous suspension polymerization. The effects of different kinds of porogen agent, toluene, toluene/n-heptane mixture or a toluene solution of polyphenyleneoxide on the bulk density, swelling in toluene and ferromagnetic properties of these materials were evaluated. The specific area and average porous diameter of network resins were characterized by BET and BJH methods, while the iron content was determined by atomic absorption spectrometry. The morphology of the composites was studied by both optical microscopy and scanning electron microscopy with energy dispersive X-ray analysis. All the spherical beads, irrespective of their sizes, have agglomerated iron particles located only on their surface. The particles have exhibited ferromagnetic behavior, with a coercivity of 328.69 Oe. The porogen agents used affect the iron particle distribution on the bead surfaces.