1,720,981 research outputs found
Chitosan and poly(methyl vinyl ether-co-maleic anhydride) microparticles as nasal sustained delivery systems.
No full textAn original dosage form for nasal delivery based on the encapsulation of hydrophilic drug in chitosan-poly(methyl vinyl ether-co-maleic anhydride) (CH-PVM/MA) microparticles prepared by spray-drying technique was developed. Microparticles were characterized in terms of morphology, size, swelling properties, encapsulation efficiency and drug release. The physical state of the drug and the polymer was determined by scanning electron microscopy (SEM) and infrared spectroscopy (IR). Propranolol hydrochloride (PH) was a β-blocker, used for the treatment of hypertension and was chosen as a model of hydrophilic drug. SEM studies showed spherical particles with smooth surfaces for chitosan hydrochloride (CH-HCl), whereas rather gross surface defects resulted from the incorporation of poly(methyl vinyl ether-co-maleic anhydride) (PVM/MA). In vitro release studies revealed a sustained release of propranolol HCl from microparticles and in particular chitosan hydrochloride provided the lowest release of drug
Perspectives of 1H-NMR-based urinary metabonomics in fabry disease
No full textHigh resolution proton magnetic resonance spectroscopy (1H-NMR) of body fluids coupled with multivariate data analysis has led to a new science known as metabonomics. Metabonomics is a powerful tool for investigating any disturbance in the normal homeostasis of biochemical processes. In particular, urine metabonomics provides information on the metabolite phenotype of the human being and is therefore appropriate to study the status of the global system. Here we applied 1H-NMR-based urinary metabonomics in a perspective study of the inherited lysosomal storage disorder known as Fabry disease, starting from the metabolite profiling of urine samples of male and female naïve Fabry subjects. Here we show that the 2 groups of patients can be fairly clearly separated into 2 classes due to statistically significant differences in the urinary level of some metabolites. This preliminary study shows that metabonomics can potentially be used for characterizing the biochemical mechanisms underlying the disease and, hopefully, for early diagnosis of Fabry disease. © 2010 Società Italiana di Nefrologia - ISSN 1121-8428
Use of Spanish Broom (Spartium junceum L.) Fibers for Removal of Heavy Metal Ions from Aqueous Solutions
No full textIn this work, potential use of Spanish broom fibers for removing from aqueous solutions heavy metal ions such as copper Cu(II) and lead Pb(II) was investigated. The fibers were extracted by DiCoDe (Digestion-Compression-Decompression) process changing experimental conditions. Morphology of fibers was evaluated by scanning electron microscopy and chemical composition, as well as the carboxylic group content, was determined by conventional methods. Various initial concentrations of heavy metal ions were studied to explore potential sorption on cellulose fibers. The results suggest that cellulose fibers, extracted by different conditions of DiCoDe process, are capable of sorbing metal ions
The influence of millimeter waves on the physical properties of large and giant unilamellar vesicles
No full textExposure of cell membranes to an electromagnetic field (EMF) in the millimeter wave band (30-300 GHz) can produce a variety of responses. Further, many of the vibrational modes in complex biomolecules fall in the 1-100 GHz range. In addition to fundamental scientific interest, this may have applications in the development of diagnostic and therapeutic medical applications. In the present work, lipid vesicles of different size were used to study the effects of exposure to radiation at 52-72 GHz, with incident power densities (IPD) of 0.0035-0.010 mW/cm2, on the chemical-physical properties of cell membranes. Large unilamellar vesicles (LUVs) were used to study the effect of the radiation on the physical stability of vesicles by dynamic light scattering. An inhibition of the aging processes (Ostwald ripening), which usually occur in these vesicles because of their thermodynamic instability, resulted. Giant unilamellar vesicles (GUVs) were used to study the effect of the radiation on membrane water permeability under osmotic stress by phase contrast microscopy. In this case, a decrease in the water membrane permeability of the irradiated samples was observed. We advance the hypothesis that both the above effects may be explained in terms of a change of the polarization states of water induced by the radiation, which causes a partial dehydration of the membrane and consequently a greater packing density (increased membrane rigidity). © 2013 Springer Science+Business Media Dordrecht
Millimeter Wave Radiations Affect Membrane Hydration in Phosphatidylcholine Vesicles
Full text linkA clear understanding of the response of biological systems to millimeter waves exposure is of increasing interest for the scientific community due to the recent convincing use of these radiations in the ultrafast wireless communications. Here we report a deuterium nuclear magnetic resonance spectroscopy (2H-NMR) investigation on the effects of millimeter waves in the 53–78 GHz range on phosphocholine bio-mimetic membranes. Millimeter waves significantly affect the polar interface of the membrane causing a decrease of the heavy water quadrupole splitting. This effect is as important as inducing the transition from the fluid to the gel phase when the membrane exposure occurs in the neighborhood of the transition point. On the molecular level, the above effect can be well explained by membrane dehydration induced by the radiation
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Effects of microwave heating for the conservation of paper artworks contaminated with Aspergillus versicolor
No full textThe conservation of the cultural heritage, such as old books, manuscripts, paintings etc. is particularly important, for both their artistic and historical values. These types of materials are often exposed to usage or storage conditions where efficient biodeterioration mechanisms take place. Deterioration of these materials occurs naturally as a result of aging, but it can be accelerated by poor storage conditions (humidity) that lead to fungi growth and negative chemically effects. Firstly, this work concerns with isolation and identification of a fungal species that infects an 18th century book. The identification was based on morphological analysis made by light and SEM microscopy and on ribosomal DNA loci amplification and sequencing. One fungal strain, Aspergillus versicolor, was identified as responsible of book biodeterioration. Then, A. versicolor was used as biodeteriogen to contaminate paper samples exposed two degradation processes (exposure to wet atmosphere and to acidic attack) simulating storage conditions of 18th century book. Secondly, microwave heating at three different temperatures (30, 58 and 63 °C) was applied on paper samples affected by spots originating from A. versicolor in order to evaluate the effectiveness of microwave in cleaning of artworks from fungi. Scanning electron microscopy and cellulose degree of polymerization were used for visual inspection and characterization of the paper samples before and after the treatments respectively. The best results were obtained by exposure of paper samples for few minutes at 58 and 63 °C, while the lower temperature (30 °C) didnât inhibit A. versicolorâs growth
Photochromic behavior of a spiro-indolino-oxazine in reverse-mode polymer dispersed liquid crystal films.
No full textVariations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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