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

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

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

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

Superabsorbent Polymers for Internally Cured Concrete

Two commercial superabsorbent polymer (SAP) formulations were used to internally cure cement pastes, mortars, and concretes with a range of water-to-cement ratios (w/c 0.35–0.52). The following properties were determined as a function of cement chemistry and type, use of chemical admixtures, use of slag, and batching parameters: SAP absorption capacity, fresh mixture workability and consistency, degree of hydration, volumetric stability, cracking tendency, compressive and flexural strength, and pumpability. SAP internal curing agents resulted in cementitious mixtures with improved hydration, accelerated strength gain, greater volumetric stability, and improved cracking resistance while maintaining sufficient workability to be pumped and placed without sacrificing compressive or flexural strength. When using SAP, batching adjustments prioritized the use of water reducing admixture instead of extra water to tune workability. While the benefits of SAP internal curing agents for low w/c mixtures were expected, SAP-containing mixtures with w/c ≥ 0.42 displayed accelerated strength development and decreased cracking tendency

Моделирование солнечной электростанции для электрификации сельских районов Мьянмы

In the recent years substantial growth of the demand for electricity took place in Myanmar; energy generation by existing sources (mainly hydropower) is not enough to provide constantly increasing consumption. The problem is most obvious in rural areas (more than 61 percent of the population) where grid extension is not justified economically whereas the cost of electricity produced by autonomous diesel generators is extremely high. (Research purpose) The purpose of this research is the evaluation of economic and technical feasibility of small off-grid (standalone) photovoltaic (PV only) and hybrid photovoltaic-diesel (PV-diesel) power generation systems providing rural household electricity consumption in Myanmar. (Materials and methods) Computer simulation using Homer pro simulation software was used. Three different load scenarios were envisaged – low, medium and high (1; 6 and 16 kilowatt-hour per day). Simulation was done for Tha Ngar village tract  with a population of about 3,000 people, which is typical in Myanmar. (Results and discussion) The results of the simulation reveal that the levelized cost of energy (LCOE) for optimal hybrid (PV-diesel) systems lies in the range 0.37-0.51 US$, for PV only systems –  0.46-0.49 US$. It proves their economic feasibility compared to conventional diesel generator systems with LCOE 0.56-1.56 US$ boosted by high fuel prices in remote areas (2-3 times higher than urban price). For the high load scenario hybrid systems are more preferable, for low load (night time lighting only) PV only systems may be more effective. Conclusions) It can be concluded that implementing solar energy is not only environmentally friendlier but also economically justified approach for providing household electricity demands of rural settlements in Myanmar without constructing expensive grid extensions.В последние годы существенный рост потребления электроэнергии в Мьянме уже не может быть удовлетворен за счет существующих источников генерации, главным образом гидроэлектростанций. Особенно остро проблема стоит в сельских районах, где проживает более 61 процента населения страны: подключение к централизованным электрическим сетям экономически не оправдано, а стоимость электроэнергии, вырабатываемой автономными дизельными генераторами, очень высока.(Цель исследования) Оценить технико-экономическую целесообразность создания и использования солнечных и гибридных солнечно-дизельных малых автономных электростанций для обеспечения базовых потребностей домохозяйств в сельских поселениях Мьянмы.(Материалы и методы) Использовали метод компьютерного моделирования в специализированной программе Homer pro. Проанализировали три сценария энергопотребления: низкий – 1 киловатт-час в день, средний – 6 киловатт-часов и высокий – 16 киловатт-часов. Моделирование проводили на примере типичного для страны сельского поселения Та Нгар с населением 3000 человек.(Результаты и обсуждение) Определили, что нормированная стоимость электроэнергии для оптимизированных гибридных систем лежит в диапазоне 0,37-0,51 доллара США, для чисто фотовольтаических электростанций – 0,46-0,49 доллара. Выявили более высокую экономическую эффективность гибридных систем по сравнению с дизельными генераторами, для которых нормированная стоимость электроэнергии составляет 0,56-1,56 доллара США с учетом сложившихся цен на топливо в отдаленных районах страны, которые превышают городские цены в 2-3 раза. Показали, что при высоком энергопотреблении предпочтительнее использование гибридных систем, для малого потребления (только ночное освещение) более эффективны чисто фотовольтаические.(Выводы) Доказали, что для удовлетворения потребностей в электроэнергии сельских поселений в Мьянме целесообразно использование солнечной энергии, что обусловлено не только экологически, но и экономически, так как исключает необходимость дорогостоящего подключения к электрическим сетям

Children’s Environmental Health Faculty Champions Initiative: A Successful Model for Integrating Environmental Health into Pediatric Health Care

BackgroundPediatric medical and nursing education lack the environmental health content needed to properly prepare health care professionals to prevent, recognize, manage, and treat environmental exposure–related diseases. The need for improvements in health care professionals’ environmental health knowledge has been expressed by leading institutions. However, few studies have evaluated the effectiveness of programs that incorporate pediatric environmental health (PEH) into curricula and practice.ObjectiveWe evaluated the effectiveness of the National Environmental Education Foundation’s (NEEF) Children’s Environmental Health Faculty Champions Initiative, which is designed to build environmental health capacity among pediatric health care professionals.MethodsTwenty-eight pediatric health care professionals participated in a train-the-trainer workshop, in which they were educated to train other health care professionals in PEH and integrate identified PEH competencies into medical and nursing practice and curricula. We evaluated the program using a workshop evaluation tool, action plan, pre- and posttests, baseline and progress assessments, and telephone interviews.ResultsDuring the 12 months following the workshop, the faculty champions’ average pretest score of 52% was significantly elevated (p < 0.0001) to 65.5% on the first posttest and to 71.5% on the second posttest, showing an increase and retention of environmental health knowledge. Faculty champions trained 1,559 health care professionals in PEH, exceeding the goal of 280 health care professionals trained. Ninety percent of faculty champions reported that PEH had been integrated into the curricula at their institution.ConclusionThe initiative was highly effective in achieving its goal of building environmental health capacity among health care professionals. The faculty champions model is a successful method and can be replicated in other arenas

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