205 research outputs found

    Barriers to Exercise in a Medical Unit of US Army Reservists: An Exploratory Study

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    Military Reservist healthcare workers must meet physical fitness standards similar to those on active duty. They, however, experience a unique occupational environment as citizen Soldiers. Their civilian careers as healthcare workers and their positions in the military both demand shift work, long hours, and critical response to high stress events. For a small group of Reservists working in civilian healthcare occupations who also serve in medical roles in the military, this exploratory study aimed to describe any perceived barriers to exercise. Although over 60% of respondents to an exercise barriers scale perceived physical and social health as the top benefits of exercising, a similar proportion viewed lack of time, time away from family, and financial cost as barriers that most interfered with their ability to exercise. Time and access to exercise, though, are imperative for mission readiness. Respondents may be at risk of not obtaining adequate exercise for optimal physical fitness

    Understanding Selectivity of Mesoporous Silica-Grafted Diglycolamide-Type Ligands in the Solid-Phase Extraction of Rare Earths

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    Rare earth elements (REEs) and their compounds are essential for rapidly developing modern technologies. These materials are especially critical in the area of green/sustainable energy; however, only very high-purity fractions are appropriate for these applications. Yet, achieving efficient REE separation and purification in an economically and environmentally effective way remains a challenge. Moreover, current extraction technologies often generate large amounts of undesirable wastes. In that perspective, the development of selective, reusable, and extremely efficient sorbents is needed. Among numerous ligands used in the liquid-liquid extraction (LLE) process, the diglycolamide-based (DGA) ligands play a leading role. Although these ligands display notable extraction performance in the liquid phase, their extractive chemistry is not widely studied when such ligands are tethered to a solid support. A detailed understanding of the relationship between chemical structure and function (i.e., extraction selectivity) at the molecular level is still missing although it is a key factor for the development of advanced sorbents with tailored selectivity. Herein, a series of functionalized mesoporous silica (KIT-6) solid phases were investigated as sorbents for the selective extraction of REEs. To better understand the extraction behavior of these sorbents, different spectroscopic techniques (solid-state NMR, X-ray photoelectron spectroscopy, XPS, and Fourier transform infrared spectroscopy, FT-IR) were implemented. The obtained spectroscopic results provide useful insights into the chemical environment and reactivity of the chelating ligand anchored on the KIT-6 support. Furthermore, it can be suggested that depending on the extracted metal and/or structure of the ligand and its attachment to KIT-6, different functional groups (i.e., C= O, N-H, or silanols) act as the main adsorption centers and preferentially capture targeted elements, which in turn may be associated with the different selectivity of the synthesized sorbents. Thus, by determining how metals interact with different supports, we aim to better understand the solid-phase extraction process of hybrid (organo)silica sorbents and design better extraction materials

    Clinical Subtypes of Depression Are Associated with Specific Metabolic Parameters and Circadian Endocrine Profiles in Women: The Power Study

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    Major depressive disorder (MDD) has been associated with adverse medical consequences, including cardiovascular disease and osteoporosis. Patients with MDD may be classified as having melancholic, atypical, or undifferentiated features. The goal of the present study was to assess whether these clinical subtypes of depression have different endocrine and metabolic features and consequently, varying medical outcomes.Premenopausal women, ages 21 to 45 years, with MDD (N = 89) and healthy controls (N = 44) were recruited for a prospective study of bone turnover. Women with MDD were classified as having melancholic (N = 51), atypical (N = 16), or undifferentiated (N = 22) features. Outcome measures included: metabolic parameters, body composition, bone mineral density (BMD), and 24 hourly sampling of plasma adrenocorticotropin (ACTH), cortisol, and leptin.Compared with control subjects, women with undifferentiated and atypical features of MDD exhibited greater BMI, waist/hip ratio, and whole body and abdominal fat mass. Women with undifferentiated MDD characteristics also had higher lipid and fasting glucose levels in addition to a greater prevalence of low BMD at the femoral neck compared to controls. Elevated ACTH levels were demonstrated in women with atypical features of depression, whereas higher mean 24-hour leptin levels were observed in the melancholic subgroup.Pre-menopausal women with various features of MDD exhibit metabolic, endocrine, and BMD features that may be associated with different health consequences.ClinicalTrials.gov NCT00006180

    Influence of cosurfactants on the properties of mesostructured materials

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    The effects of the addition of two different types of cosurfactants, n-alkylamine and n-alkyl alcohol, on he phase behavior of silicate-surfactant mesophases and the pore size of the calcined materials have been investigated using X-ray diffraction, N-2-sorption, TG-MS, and solid state H-1 and C-13 NMR spectroscopy. The cosurfactants were added to a standard room-temperature synthesis, which results in a MCM-41 type, hexagonally ordered material in the absence of cosurfactant. Their addition led either to an increase or a decrease of the pore size and d spacing of the hexagonal mesophase, depending on the nature of the polar headgroup and on the chain length of the cosurfactant. For high cosurfactant/surfactant ratios, however, a transition to a lamellar phase was usually observed. The d spacing and the pore size of the hexagonal mesophase can be decreased considerably down to the supermicropore range by addition of butylamine without a marked decrease in the long- range order of the material. The addition of alcohol, on the other hand, resulted in an increase in the d spacing of the hexagonal phase by up to 3 Angstrom. These results are discussed in terms of differences in the ability of the cosurfactants to interact with the silicate as well as cosurfactant-induced changes in the packing parameter

    Influence of cosurfactants on the properties of mesostructured materials

    No full text
    The effects of the addition of two different types of cosurfactants, n-alkylamine and n-alkyl alcohol, on he phase behavior of silicate-surfactant mesophases and the pore size of the calcined materials have been investigated using X-ray diffraction, N-2-sorption, TG-MS, and solid state H-1 and C-13 NMR spectroscopy. The cosurfactants were added to a standard room-temperature synthesis, which results in a MCM-41 type, hexagonally ordered material in the absence of cosurfactant. Their addition led either to an increase or a decrease of the pore size and d spacing of the hexagonal mesophase, depending on the nature of the polar headgroup and on the chain length of the cosurfactant. For high cosurfactant/surfactant ratios, however, a transition to a lamellar phase was usually observed. The d spacing and the pore size of the hexagonal mesophase can be decreased considerably down to the supermicropore range by addition of butylamine without a marked decrease in the long- range order of the material. The addition of alcohol, on the other hand, resulted in an increase in the d spacing of the hexagonal phase by up to 3 Angstrom. These results are discussed in terms of differences in the ability of the cosurfactants to interact with the silicate as well as cosurfactant-induced changes in the packing parameter

    Drug release from biodegradable silica fibers

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    Sol-gel derived biodegradable SiO2 gel fibers have been prepared and characterized by Raman spectroscopy, SEM, Si-29 MAS NMR and TG=MS, respectively. An active component, dexmedetomidine hydrochloride, was incorporated in situ into the fiber structure, by adding it to the sol used for fiber spinning. The subsequent release of the active component was studied in vitro and shown to be determined by differences in the fiber structure, for which clear but indirect evidence was obtained from the different characterization methods used. (C) 2002 Published by Elsevier Science B.V

    Large-pore mesoporous RuNi-doped TiO(2)-Al(2)O(3) nanocomposites forhighly efficient selective CO methanation in hydrogen-rich reformate gases

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    Available online 31 October 2014Abstract not availableXiaoping Dai, Ji Liang, Ding Ma, Xin Zhang, Huabo Zhao, Bo Zhao, Zhenguo Guo, Freddy Kleitz, Shizhang Qia
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