56 research outputs found

    Experimental Determination of Nucleation Scaling Law for Small Charged Particles

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    We investigated the nucleation process at the molecular level. Controlled sticking of individual atoms onto mass selected clusters over a wide mass range has been carried out for the first time. We measured the absolute unimolecular nucleation cross sections of cationic sodium clusters Na_{n}^{+} in the range n=25-200 at several collision energies. The widely used hard sphere approximation clearly fails for small sizes: not only should vapor-to-liquid nucleation theories be modified, but also, through the microreversibility principle, cluster decay rate statistical models

    Synchrotron X-ray diffraction experiments with a prototype hybrid pixel detector

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    A prototype X-ray pixel area detector (XPAD3.1) has been used for X-ray diffraction experiments with synchrotron radiation. The characteristics of this detector are very attractive in terms of fast readout time, high dynamic range and high signal-to-noise ratio. The prototype XPAD3.1 enabled various diffraction experiments to be performed at different energies, sample-to-detector distances and detector angles with respect to the direct beam, yet it was necessary to perform corrections on the diffraction images according to the type of experiment. This paper is focused on calibration and correction procedures to obtain high-quality scientific results specifically developed in the context of three different experiments, namely mechanical characterization of nanostructured multilayers, elastic-plastic deformation of duplex steel and growth of carbon nanotubes

    Die Stoffwechselwirkungen der SchilddrĂĽsenhormone

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    Bioidentical menopausal hormone therapy: registered hormones (non-oral estradiol ± progesterone) are optimal

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    The many advantages of registered bioidentical sex hormones over registered, conventional, non-bioidentical menopausal hormone therapy (MHT) are considered. The transdermal route of estrogen administration avoids excess venous thromboembolic and ischemic stroke events. There is some indication that conjugated equine estrogens are more thrombogenic and most likely induce some hypertensive responses; estradiol might also be superior to conjugated equine estrogens (CEE) in terms of global cardiovascular health. The most valid evidence presently suggests that CEE-only treatment does not increase the risk of breast cancer and even may reduce it. But its combination with a synthetic progestogen (mainly medroxyprogesterone acetate) is a critical issue since it seems to be primarily associated with an increased incidence of breast cancer, however similar to or lower than that associated with some common lifestyle factors. Though not yet proven in a randomized, controlled trial, MHT continuously combining oral micronized progesterone with transdermal estradiol can presently be considered as the optimal MHT. It is not only safer than custom-compounded bioidentical hormones but also than oral conventional MHT and has the best breast profile; registered products for such optimal MHT are available around the world and must be preferred.SCOPUS: re.jinfo:eu-repo/semantics/publishe

    HRT optimization, using transdermal estradiol plus micronized progesterone, a safer HRT

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    Hormone replacement therapy (HRT) remains the gold standard for treatment of climacteric symptoms in menopausal women; it is relatively safe in healthy subjects for at least 5 years, provided it had been initiated before the age of 60 years and/or within 10 years from menopause. Estrogen probably adds some cardioprotection, that can, however, be obscured by progestogens, especially medroxyprogesterone acetate (MPA). Oral HRT is associated with an increased risk of venous thromboembolism (VTE), gallbladder disease and possibly stroke. The increased occurrence of all these events can be prevented by the use of the transdermal route of estradiol administration; this route seems also advantageous for women with diabetes, hypertension and other cardiovascular risk factors, and also especially with advancing age. Endometrial protection by any progestogen is insufficient in the mid to long term when cyclical, sequential regimens are used; full protection can be secured only by continuous combined estrogen + progestogen. Natural, 'body-identical' progesterone, devoid of any androgenic as well as glucocorticoid activities but being slightly hypotensive due to its antimineralocorticoid activity, appears to be the optimal progestogen in terms of cardiovascular effects, blood pressure, VTE, probably stroke and even breast cancer (contrary to synthetic progestogens and particularly MPA, which appear to be mitogenic on breast cells, in synergism with estrogen). HRT optimization can thus be achieved by combining low doses of estrogen given transdermally with micronized oral progesterone; such optimized HRT will allow us to treat symptomatic women for as long as required. Asymptomatic women at risk of (osteoporotic) fractures can also be treated with this optimized HRT as long as their individual risk/benefit ratio remains favorable (thanks to the absence of increased risks of VTE, stroke and breast cancer). © 2013 International Menopause Society.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

    Nanometric confinement: Toward new physical properties and technological developments

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    In numerous real life situations, molecular systems are not found in bulk but instead trapped in limited volumes of nanometric size: this is nanometric confinement. The complex interplay of the confinement topology, dimensionality (3D to 1D) and surface/volume ratio significantly affects the physical properties of the confined material. After decades of intense fundamental research, we are now entering a time when the unusual properties of fluids under confinement may be tuned to target specific technological objectives. In this paper, we highlight few situations, all related to the fields of energy production or storage, where diverse neutron scattering techniques (imaging, small angle scattering, diffraction, inelastic and quasi-elastic scattering) may help to bridge basic science and applied research
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