776 research outputs found
Incorporating Environmental Health into Pediatric Medical and Nursing Education
Pediatric medical and nursing education currently lacks the environmental health content necessary to appropriately prepare pediatric health care professionals to prevent, recognize, manage, and treat environmental-exposure–related disease. Leading health institutions have recognized the need for improvements in health professionals’ environmental health education. Parents are seeking answers about the impact of environmental toxicants on their children. Given the biologic, psychological, and social differences between children and adults, there is a need for environmental health education specific to children. The National Environmental Education and Training Foundation, in partnership with the Children’s Environmental Health Network, created two working groups, one with expertise in medical education and one with expertise in nursing education. The working groups reviewed the transition from undergraduate student to professional to assess where in those processes pediatric environmental health could be emphasized. The medical education working group recommended increasing education about children’s environmental health in the medical school curricula, in residency training, and in continuing medical education. The group also recommended the expansion of fellowship training in children’s environmental health. Similarly, the nursing working group recommended increasing children’s environmental health content at the undergraduate, graduate, and continuing nursing education levels. Working groups also identified the key medical and nursing organizations that would be important in leveraging these changes. A concerted effort to prioritize pediatric environmental health by governmental organizations and foundations is essential in providing the resources and expertise to set policy and provide the tools for teaching pediatric environmental health to health care providers
Formation of gold nanoparticles in polymeric nanowires by low-temperature thermolysis of gold mesitylene
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.The formation of polymer nanowires containing metal nanoparticle chains by low-temperature thermolyses of metal precursors has remained challenging. We report the block copolymer-assisted generation of locally regular chains of quasi-spherical gold nanoparticles with narrow particle diameter distribution by mild thermolysis of the non-polar gold precursor gold mesitylene inside the cylindrical nanopores of self-ordered anodic aluminium oxide (AAO). The block copolymer separates the gold mesitylene as well as the developing gold nanoparticles from the AAO pore walls so that surface nucleation and pinning of gold clusters are prevented. Growing quasi-spherical gold nanoparticles locally deform the polymer chains irreversibly adsorbed on the AAO pore walls, and the polymer chains are pushed into the space between the gold nanoparticles. The gold nanoparticles have, therefore, larger diameters and smaller specific surface than hypothetical pluglike gold entities with the same volume, the formation of which is suppressed.DFG, SPP 1165, Nanodrähte und Nanoröhren: von kontrollierter Synthese zur Funktio
Diffraction effects in the Recoil-Frame Photoelectron Angular Distributions of Halomethanes
Citation: Bomme, C., Anielski, D., Savelyev, E., Boll, R., Erk, B., Bari, S., . . . Rolles, D. (2015). Diffraction effects in the Recoil-Frame Photoelectron Angular Distributions of Halomethanes. 635(11). doi:10.1088/1742-6596/635/11/112020We have measured the Recoil Frame-Photoelectron Angular Distributions (RF-PADs) for inner-shell photoionization of CH3F, CH3I and CF3I halomethane molecules for photoelectron energies up to 300 eV detected within a 4? solid angle in the gas-phase. For high kinetic energies, the RF-PADs are dominated by diffraction effects that encode information on the molecular geometry. © Published under licence by IOP Publishing Ltd
Charge transfer in dissociating iodomethane and fluoromethane molecules ionized by intense femtosecond X-ray pulses
Citation: Boll, R., Erk, B., Coffee, R., Trippel, S., Kierspel, T., Bomme, C., . . . Rudenko, A. (2016). Charge transfer in dissociating iodomethane and fluoromethane molecules ionized by intense femtosecond X-ray pulses. Structural Dynamics, 3(4). doi:10.1063/1.4944344Additional Authors: Marchenko, T.;Miron, C.;Patanen, M.;Osipov, T.;Schorb, S.;Simon, M.;Swiggers, M.;Techert, S.;Ueda, K.;Bostedt, C.;Rolles, D.;Rudenko, A.Ultrafast electron transfer in dissociating iodomethane and fluoromethane molecules was studied at the Linac Coherent Light Source free-electron laser using an ultraviolet-pump, X-ray-probe scheme. The results for both molecules are discussed with respect to the nature of their UV excitation and different chemical properties. Signatures of long-distance intramolecular charge transfer are observed for both species, and a quantitative analysis of its distance dependence in iodomethane is carried out for charge states up to I21+. The reconstructed critical distances for electron transfer are in good agreement with a classical over-the-barrier model and with an earlier experiment employing a near-infrared pump pulse. © 2016 Author(s)
Imaging Molecular Structure through Femtosecond Photoelectron Diffraction on Aligned and Oriented Gas-Phase Molecules
This paper gives an account of our progress towards performing femtosecond
time-resolved photoelectron diffraction on gas-phase molecules in a pump-probe
setup combining optical lasers and an X-ray Free-Electron Laser. We present
results of two experiments aimed at measuring photoelectron angular
distributions of laser-aligned 1-ethynyl-4-fluorobenzene (C8H5F) and
dissociating, laseraligned 1,4-dibromobenzene (C6H4Br2) molecules and discuss
them in the larger context of photoelectron diffraction on gas-phase molecules.
We also show how the strong nanosecond laser pulse used for adiabatically
laser-aligning the molecules influences the measured electron and ion spectra
and angular distributions, and discuss how this may affect the outcome of
future time-resolved photoelectron diffraction experiments.Comment: 24 pages, 10 figures, Faraday Discussions 17
Coulomb explosion imaging of small organic molecules at LCLS.
Fragmentation of small organic molecules by intense few-femtosecond X-ray free-electron laser pulses has been studied using Coulomb explosion imaging. By measuring kinetic energies and emission angles of the ionic fragments in coincidence, we disentangle different fragmentation pathways, for certain cases can reconstruct molecular geometry at the moment of explosion, and show how it depends on LCLS pulse duration
Communication: X-ray coherent diffractive imaging by immersion in nanodroplets
Citation: Tanyag, R. M. P., Bernando, C., Jones, C. F., Bacellar, C., Ferguson, K. R., Anielski, D., . . . Vilesov, A. F. (2015). Communication: X-ray coherent diffractive imaging by immersion in nanodroplets. Structural Dynamics, 2(5), 9. doi:10.1063/1.4933297Lensless x-ray microscopy requires the recovery of the phase of the radiation scattered from a specimen. Here, we demonstrate a de novo phase retrieval technique by encapsulating an object in a superfluid helium nanodroplet, which provides both a physical support and an approximate scattering phase for the iterative image reconstruction. The technique is robust, fast-converging, and yields the complex density of the immersed object. Images of xenon clusters embedded in superfluid helium droplets reveal transient configurations of quantum vortices in this fragile system. (C) 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.Additional Authors: Neumark, D. M.;Rolles, D.;Rudek, B.;Rudenko, A.;Siefermann, K. R.;Ullrich, J.;Weise, F.;Bostedt, C.;Gessner, O.;Vilesov, A. F
Synthesis and Characterization of Polymer-Silica Composite Hydrogel Particles and Influence of Hydrogel Composition on Cement Paste Microstructure
The objective of this research is to define the fundamental structure-property relationships of water-swollen polymer hydrogel particles that are employed as internal curing agents in cementitious mixtures, in addition to reporting a novel synthesis procedure for combining pozzolanic materials with hydrogel particles. Solution polymerization was performed to incorporate amorphous nanosilica particles within acrylic-based polymer hydrogel particles of varying chemical compositions (i.e., monomer ratio of acrylic acid (AA) to acrylamide (AM)). Experiments were designed to measure the absorption capacity and kinetics of hydrogel particles immersed in pure water and cementitious pore solution, as well as determine the impact of particles on cement paste microstructure. While majority-AM hydrogel particles displayed relatively stable absorption values during immersion in pore solution, majority-AA hydrogel particles desorbed fluid over time, most likely due to the interactions of multivalent cations in the absorbed solution with the anionic polymer network. Interestingly, the addition of negatively charged nanosilica particles accelerated and enhanced this desorption response. When incorporated into cement paste, majority-AM hydrogel particles encouraged the formation of calcium hydroxide and calcium silicate hydrate within the void space previously occupied by the swollen particles. When nanosilica was added to the hydrogel particles, a 53 % increase in the number of hydrogel voids containing hydrated product was observed for the 17 % AA hydrogel particles, and a 140 % increase was observed for the 83 % AA hydrogel particles. These results suggest that the combination of nanosilica with polymeric hydrogel particles provides a favorable environment for the pozzolanic reaction to proceed and that nanosilica aids in the replenishment of hydrogel void space with hydrated cement phases
Hetero-site-specific X-ray pump-probe spectroscopy for femtosecond intramolecular dynamics
Citation: Picon, A., Lehmann, C. S., Bostedt, C., Rudenko, A., Marinelli, A., Osipov, T., . . . Southworth, S. H. (2016). Hetero-site-specific X-ray pump-probe spectroscopy for femtosecond intramolecular dynamics. Nature Communications, 7, 6. doi:10.1038/ncomms11652New capabilities at X-ray free-electron laser facilities allow the generation of two-colour femtosecond X-ray pulses, opening the possibility of performing ultrafast studies of X-ray-induced phenomena. Particularly, the experimental realization of hetero-site-specific X-ray-pump/X-ray-probe spectroscopy is of special interest, in which an X-ray pump pulse is absorbed at one site within a molecule and an X-ray probe pulse follows the X-ray-induced dynamics at another site within the same molecule. Here we show experimental evidence of a hetero-site pump-probe signal. By using two-colour 10-fs X-ray pulses, we are able to observe the femtosecond time dependence for the formation of F ions during the fragmentation of XeF2 molecules following X-ray absorption at the Xe site
- …
