744 research outputs found

    Skin Permeability In Vivo: Comparison in Rat, Rabbit, Pig and Man

    Get PDF
    A comparative study was undertaken in rats, rabbits, miniature swine and man, in which the percutaneous absorption of the following compounds, labeled with 14C or 35S, were studied: haloprogin, N-acetylcysteine, cortisone, testosterone, caffeine and butter yellow. The amount of radioactivity excreted in urine for 5 days following application of the test compound to the skin was employed as the index for quantifying skin penetration. A special nonocclusive foam pad device for rabbits and miniature swine was developed to prevent artifacts resulting from transfer of drug to the urine by any route other than percutaneous absorption. The dose was 4 μg/cm2 of skin surface. The excretion data obtained from the topical studies were adjusted for recovery of radioactivity following intravenous administration of the radioactive drug. The results obtained in this study indicated that skin permeability decreases in the following order: rabbit, rat, pig and man. Overall, skin of miniature swine has the closest permeability characteristics to that of human skin with this series of compounds

    Impact of 3-Cyanopropionic Acid Methyl Ester on the Electrochemical Performance of ZnMnâ‚‚Oâ‚„ as Negative Electrode for Li-Ion Batteries

    Get PDF
    Due to their high theoretical capacity, transition metal oxide compounds are promising electrode materials for lithium-ion batteries. However, one drawback is associated with relevant capacity fluctuations during cycling, widely observed in the literature. Such strong capacity variation can result in practical problems when positive and negative electrode materials have to be matched in a full cell. Herein, the study of ZnMn2O4 (ZMO) in a nonconventional electrolyte based on 3-cyanopropionic acid methyl ester (CPAME) solvent and LiPF6 salt is reported for the first time. Although ZMO in LiPF6/CPAME electrolyte displays a dramatic capacity decay during the first cycles, it shows promising cycling ability and a suppressed capacity fluctuation when vinylene carbonate (VC) is used as an additive to the CPAME-based electrolyte. To understand the nature of the solid electrolyte interphase (SEI), the electrochemical study is correlated to ex situ X-ray photoelectron spectroscopy (XPS)

    Potentials in Li-Ion Batteries Probed by Operando Ambient Pressure Photoelectron Spectroscopy

    Get PDF
    The important electrochemical processes in a battery happen at the solid/liquid interfaces. Operando ambient pressure photoelectron spectroscopy (APPES) is one tool to study these processes with chemical specificity. However, accessing this crucial interface and identifying the interface signal are not trivial. Therefore, we present a measurement setup, together with a suggested model, exemplifying how APPES can be used to probe potential differences over the electrode/electrolyte interface, even without direct access to the interface. Both the change in electron electrochemical potential over the solid/liquid interface, and the change in Li chemical potential of the working electrode (WE) surface at Li-ion equilibrium can be probed. Using a Li4Ti5O12 composite as a WE, our results show that the shifts in kinetic energy of the electrolyte measured by APPES can be correlated to the electrochemical reactions occurring at the WE/electrolyte interface. Different shifts in kinetic energy are seen depending on if a phase transition reaction occurs or if a single phase is lithiated. The developed methodology can be used to evaluate charge transfer over the WE/electrolyte interface as well as the lithiation/delithiation mechanism of the WE

    Cryptococcus gattii Meningoencephalitis in an Immunocompetent Person 13 Months after Exposure

    Get PDF
    Abstract : A 53-year old immunocompetent Swiss female is described who developed severe meningoencephalitis due to infection with Cryptococcus gattii 13 months following exposure on Vancouver Island, Canada. Diagnosis was based on cerebrospinal fluid (CSF) examination, i.e., positive India-ink staining, positive latex particle agglutination, and positive culture. Species identification was performed by growth on L-canavanine-glycine-bromthymol blue medium and by sequencing of the intergenic and internal transcribed spacer regions of the rRNA genes. After initial therapy with fluconazole by which the patient did not improve, therapy was changed to amphotericin B and flucytosine and later to high-dose fluconazole and amphotericin B. Despite long-term treatment and external drainage of the CSF, the patient's condition improved only slowly. The patient was discharged after 132 days of hospitalizatio
    • …
    corecore