Production of H<Subscript>2</Subscript>S and properties of sulfite reductase from selected strains of wine-producing yeasts

Correlation between H₂S productivity (p) and sulfite reductase activity (A) was estimated for seven wine-producing yeasts. It was described by a linear function p=f(A), the slope of which depended on the yeast strain. The most intensive H₂S synthesis by all the examined yeasts was observed within the early logarithmic growth phase, either in nitrogen abundance and SO₂ presence, or in nitrogen deficient and SO₂-free medium. Sulfite reductase from all the strains was optimally active at pH close to 7.4. The enzyme from cryophilic yeasts displayed maximum activity at approximately 16 °C, and from mesophiles at 22–26 °C. The preparations showed different affinities toward sulfite (K_m of 16.7–67.5 M). Values of activation energy in sulfite reduction depended on the yeast, and ranged from 14.07 to 67.04 kJ mol^–1.     

Polyblend fibers from polypropylene and mercapto-modified EVA

Polyblend fibers were made from mixtures of polypropylene (PP) and ethylene-vinyl acetate copolymers (EVA) or their mercapto-modified products [poly(ethylene-co-vinyl acetate-co-vinyl mercaptoacetate)] (EVASH). The presence of few EVA or EVASH in the PP fibers results in an increasing of the elastic modulus, indicating a reinforcing action of these functional polymers. The composition surface of the modified PP fibers was analyzed by X-ray photoelectron spectroscopy and diffuse reflectance infrared Fourier transform spectroscopy. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2243–2249, 1997     

The effects of clay dispersion on the mechanical,physical, and flame‐retarding properties of wood fiber/polyethylene/clay nanocomposites

In this study, nanosized clay particles were introduced into wood fiber/plastic composites (WPCs) to improve their mechanical properties and flame retardancy, which are especially important in various automotive and construction applications. A high degree of exfoliation for nanoclay in the wood fiber/high density polyethylene (HDPE) composites was successfully achieved with the aid of maleated HDPE (PE‐g‐MAn), through a melt blending masterbatch process. The structures and morphologies of the composites were determined using X‐ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. This article presents the effects of clay content and degree of clay dispersion on the mechanical and physical properties and flame retardancy of wood fiber/HDPE composites that contained a small amount of clay, in the range of 3–5 wt %. We concluded that achieving a higher degree of dispersion for the nanosized clay particles is critical to enhance the mechanical properties and the flame retardancy of WPCs when small amounts of clay are used. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Surface modification of ultra‐high‐molecular‐weight polyethylene. II. Effect on the physicomechanical and tribological properties of ultra‐high‐molecular‐weight polyethylene/poly(ethylene terephthalate) composites

We performed surface modification of ultra‐high‐molecular‐weight polyethylene (UHMWPE) through chromic acid etching, with the aim of improving the performance of its composites with poly(ethylene terephthalate) (PET) fibers. In this article, we report on the morphology and physicomechanical and tribological properties of modified UHMWPE/PET composites. Composites containing chemically modified UHMWPE had higher impact properties than those based on unmodified UHMWPE because of improved interfacial bonding between the polymer matrix and the fibers and better dispersion of the fibers within the modified UHMWPE matrix. Chemical modification of UHMWPE before the introduction of PET fibers resulted in composites exhibiting improved wear resistance compared to the base material and compared to unmodified UHMWPE/PET composites. On the basis of the morphological studies of worn samples, microploughing and fatigue failure associated with microcracking were identified as the principle wear mechanisms. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Novel spectropolarimeter employing fixed polarizers for the determination of optically active samples

A novel spectropolarimeter, based on modification of an ordinary, inexpensive, multiwavelength ultraviolet (UV)-visible-near-infrared (NIR) spectrophotometer, is described and applied to the determination of sucrose, sucrose inversion, and enantiomeric composition of solutions of (R)-(+)-limonene and (S)-(-)-limonene. The instrument has no moving parts, and optical rotation measurements are encoded as an apparent absorbance. Apparent absorbance measurements can be combined with multivariate statistical analysis over a wide spectral range, and a background correction technique that employs the sample as its own blank provides an effective means of correcting for the presence of chromophores that also absorb over the wavelengths of interest. The instrument was tested against an ordinary polarimeter and showed good performance with both colorless and colored samples.     

Morphoanatomical and phytochemical studies of Salvia lachnostachys (Lamiaceae)

Salvia lachnostachys Benth., Lamiaceae, is a endemic species from southern Brazil. The essential oil of its leaves and flowers is mainly constituted by aliphatic compounds, such as dodecanoic acid, with sesquiterpenes as minor constituents. This work evaluated the morphology, anatomy, microchemistry, and phytochemistry of S. lachnostachys to provide advanced knowledge of Brazilian plants with medicinal potential. Light and scanning electron microscopy techniques were used in the anatomical and microchemical studies. Compounds were isolated by chromatographic techniques, identified by analysis of their NMR spectra and compared with published data. S. lachnostachys can be distinguished from other related species mainly by its petiolate leaves, terminal inflorescence, persistent bracts, and villous‐glandular corolla. The stem and leaves of S. lachnostachys display anatomical characteristics common to the family Lamiaceae. However, this species can be distinguished from other family members by the morphology and the presence of eglandular and glandular trichomes, as well as the organization of the vascular bundles of the petiole. The phytochemical results revealed that S. lacnostachys produces oleanolic and ursolic acids in addition to the diterpene fruticuline A, which is a rare compound, previously found only in Salvia fruticulosa Benth. and S. corrugata Vahl. Ursolic and oleanolic acids are bioactive triterpenes that exhibit antiatherosclerotic, anticancer, antihypertensive, antinflammatory, antileukemic, antimutagenic, antioxidant, antiproliferative, and antiviral activities, and fruticuline A has antibacterial activity. Microsc. Res. Tech. © 2012 Wiley Periodicals, Inc.     

Fluid Mixing for Low‐Power ‘Digital Microfluidics’ Using Electroactive Molecular Monolayers

A switchable electrode, which relies on an indium‐tin oxide conductive substrate coated with a self‐assembled monolayer terminated with an anthraquinone group (AQ), is reported as an electrowetting system. AQ electrochemical features confer the capability of yielding a significant modulation of surface wettability as high as 26° when its redox state is switched. Hence, an array of planar electrodes for droplets actuation is fabricated and integrated in a microfluidic device to perform mixing and dispensing on sub‐nanoliter scale. Vehiculation of cells across microfluidic compartments is made possible by taking full advantage of surface electrowetting in culture medium.     

Topologically controlled growth of magnetic-metal-functionalized semiconductor oxide nanorods

Colloidal semiconductor-magnetic hybrid nanocrystals with topologically controlled composition are fabricated by heterogeneous nucleation of spherical epsilon-Co domains onto anatase TiO2 nanorods. The latter can be selectively decorated at either their tips or at multiple locations along their longitudinal sidewalls, forming lattice-matched heterointerfaces regardless of the metal deposition sites. The possibility of switching between either heterostructure growth modes arises from the facet-dependent chemical reactivity of the oxide seeds, which is governed mainly by selective adhesion of the surfactants rather than by small differences in misfit-induced interfacial strain at the relevant junction points.     

Engineered Multifunctional Albumin‐Decorated Porous Silicon Nanoparticles for FcRn Translocation of Insulin

The last decade has seen remarkable advances in the development of drug delivery systems as alternative to parenteral injection‐based delivery of insulin. Neonatal Fc receptor (FcRn)‐mediated transcytosis has been recently proposed as a strategy to increase the transport of drugs across the intestinal epithelium. FcRn‐targeted nanoparticles (NPs) could hijack the FcRn transcytotic pathway and cross the epithelial cell layer. In this study, a novel nanoparticulate system for insulin delivery based on porous silicon NPs is proposed. After surface conjugation with albumin and loading with insulin, the NPs are encapsulated into a pH‐responsive polymeric particle by nanoprecipitation. The developed NP formulation shows controlled size and homogeneous size distribution. Transmission electron microscopy (TEM) images show successful encapsulation of the NPs into pH‐sensitive polymeric particles. No insulin release is detected at acidic conditions, but a controlled release profile is observed at intestinal pH. Toxicity studies show high compatibility of the NPs with intestinal cells. In vitro insulin permeation across the intestinal epithelium shows approximately fivefold increase when insulin is loaded into FcRn‐targeted NPs. Overall, these FcRn‐targeted NPs offer a toolbox in the development of targeted therapies for oral delivery of insulin.