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Sample records for alane alh3 nanoparticles

  1. Formation of Al2H7- anions--indirect evidence of volatile AlH3 on sodium alanate using solid-state NMR spectroscopy.

    PubMed

    Felderhoff, Michael; Zibrowius, Bodo

    2011-10-14

    After more than a decade of intense research on NaAlH(4) doped with transition metals as hydrogen storage material, the actual mechanism of the decomposition and rehydrogenation reaction is still unclear. Early on, monomeric AlH(3) was named as a possible transport shuttle for aluminium, but never observed experimentally. Here we report for the first time the trapping of volatile AlH(3) produced during the decomposition of undoped NaAlH(4) by an adduct of sodium alanate and crown ether. The resulting Al(2)H(7)(-) anion was identified by solid-state (27)Al NMR spectroscopy. Based on this indirect evidence of volatile alane, we present a simple description of the processes occurring during the reversible dehydrogenation of NaAlH(4). PMID:21879065

  2. Novel methods for synthesizing halide-free alane without the formation of adducts

    NASA Astrophysics Data System (ADS)

    Dinh, Long V.; Knight, Douglas A.; Paskevicius, Mark; Buckley, Craig E.; Zidan, Ragaiy

    2012-04-01

    Many of the current synthesis methods for aluminum hydride (alane—AlH3) involve reacting AlCl3 and LiAlH4 in solvents. The reaction requires the formation of an alane adduct such as AlH3ṡ[(C2H5)2O] prior to obtaining crystallized stable α-AlH3. This process requires several hours of pumping in a vacuum system to remove the ether and convert the alane etherate into stable α-alane. This crystallization process is both costly and hazardous because a large amount of highly flammable material (e.g. ether) is removed by vacuum pumps over several hours. Conversely, the work presented herein describes novel methods to synthesize adduct-free alane. It is demonstrated here that AlH3 can form by mixing AlCl3 and LiAlH4 in the solid state and heating to 75∘C; only α-AlH3 was obtained. The α-AlH3 product can be washed with minimal solvents leading to zero formation of alane adducts. In addition, the unwanted LiCl by-product is also removed during the solvent wash, resulting in halide-free α-alane. Although simply mixing and heating the reactants led to a 40% yield of alane, having the reactants compacted and mechanically pressed while heating increases the yield to 60% crystalline α-AlH3.

  3. Towards direct synthesis of alane: A predicted defect-mediated pathway confirmed experimentally

    DOE PAGESBeta

    Wang, Lin -Lin; Herwadkar, Aditi; Reich, Jason M.; Johnson, Duane D.; House, Stephen D.; Pena-Martin, Pamela; Rockett, Angus A.; Robertson, Ian M.; Gupta, Shalabh; Pecharsky, Vitalij K.

    2016-08-18

    Here, alane (AlH3) is a unique energetic material that has not found a broad practical use for over 70 years because it is difficult to synthesize directly from its elements. Using density functional theory, we examine the defect-mediated formation of alane monomers on Al(111) in a two-step process: (1) dissociative adsorption of H2 and (2) alane formation, which are both endothermic on a clean surface. Only with Ti dopant to facilitate H2 dissociation and vacancies to provide Al adatoms, both processes become exothermic. In agreement, in situ scanning tunneling microscopy showed that during H2 exposure, alane monomers and clusters formmore » primarily in the vicinity of Al vacancies and Ti atoms. Moreover, ball milling of the Al samples with Ti (providing necessary defects) showed a 10 % conversion of Al into AlH3 or closely related species at 344 bar H2, indicating that the predicted pathway may lead to the direct synthesis of alane from elements at pressures much lower than the 104 bar expected from bulk thermodynamics.« less

  4. Towards Direct Synthesis of Alane: A Predicted Defect-Mediated Pathway Confirmed Experimentally.

    PubMed

    Wang, Lin-Lin; Herwadkar, Aditi; Reich, Jason M; Johnson, Duane D; House, Stephen D; Peña-Martin, Pamela; Rockett, Angus A; Robertson, Ian M; Gupta, Shalabh; Pecharsky, Vitalij K

    2016-09-01

    Alane (AlH3 ) is a unique energetic material that has not found a broad practical use for over 70 years because it is difficult to synthesize directly from its elements. Using density functional theory, we examine the defect-mediated formation of alane monomers on Al(111) in a two-step process: (1) dissociative adsorption of H2 and (2) alane formation, which are both endothermic on a clean surface. Only with Ti dopant to facilitate H2 dissociation and vacancies to provide Al adatoms, both processes become exothermic. In agreement, in situ scanning tunneling microscopy showed that during H2 exposure, alane monomers and clusters form primarily in the vicinity of Al vacancies and Ti atoms. Moreover, ball milling of the Al samples with Ti (providing necessary defects) showed a 10 % conversion of Al into AlH3 or closely related species at 344 bar H2 , indicating that the predicted pathway may lead to the direct synthesis of alane from elements at pressures much lower than the 10(4)  bar expected from bulk thermodynamics. PMID:27535100

  5. AlH 3 between 65 and 110 GPa: Implications of electronic band and phonon structures

    NASA Astrophysics Data System (ADS)

    Islam, A. K. M. A.; Ali, M. M.; Ali, M. L.

    2010-04-01

    A first-principles density-functional-theory method has been used to reinvestigate the mechanical and dynamical stability of the metallic phase of AlH 3 between 65 and 110 GPa. The electronic properties and phonon dynamics as a function of pressure are also explored. We find electron-phonon superconductivity in the cubic Pm-3 n structure with critical temperature T c = 37 K at 70 GPa which decreases rapidly with the increase of pressure. Further unlike a previously calculated T c-value of 24 K at 110 GPa, we do not find any superconductivity of significance at this pressure which is consistent with experimental observation.

  6. Elastic, superconducting, and thermodynamic properties of the cubic metallic phase of AlH3 via first-principles calculations

    NASA Astrophysics Data System (ADS)

    Wei, Yong-Kai; Ge, Ni-Na; Ji, Guang-Fu; Chen, Xiang-Rong; Cai, Ling-Cang; Zhou, Su-Qin; Wei, Dong-Qing

    2013-09-01

    The lattice dynamic, elastic, superconducting, and thermodynamic properties of the high-pressure cubic metallic phase AlH3 are studied within density function theory. The calculated elastic modulus and phonon dispersion curves at various pressures indicate that the cubic phase is both mechanically and dynamically stable above 73 GPa. The superconducting transition temperature was calculated using Allen-Dynes modification of the McMillan formula based on the Bardeen-Cooper-Schrieffer theory. It is found that Tc approaches a linear decrease in the low pressure range at the rate dTC/dP ≈-0.22 K/GPa but gradually decreases exponentially at higher pressure, and then it becomes 0 K upon further compression. The calculations indicate that Tc is about 2.042 K at 110 GPa, in agreement with experimental results. The soft phonon modes, especially the lowest acoustic mode, contribute almost 79% to the total electron-phonon coupling parameter sλ for cubic AlH3 at 73 GPa. However, they disappear gradually with increasing pressure, showing a responsibility for the variation of Tc. The thermodynamic properties of cubic AlH3, such as the dependence of thermal expansion coefficient αV on pressure and temperature, the specific heat capacity CP, as well as the electronic specific heat coefficient Cel, were also investigated by the quasi-harmonic approximation theory.

  7. Regeneration of AlH3 studied with Raman and Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Lacina, David; Wegrzyn, J.; Reilly, J. J.; Graetz, Jason

    2010-03-01

    Aluminum hydride compounds are known to exhibit a 10% by weight hydrogen storage capacity that makes them suited for technologies that require hydrogen as a fuel. The current challenge associated with this material is how to regenerate the hydride from the spent fuel and H2 gas. We employ a two-step process to regenerate the hydride compound which first requires the formation of a stable aluminum hydride adduct using a tertiary amine. This is followed by a second step consisting of adduct separation and hydride recovery, involving transamination to create a less stable adduct. We present results which show that alane-amines can be formed by hydrogenation of catalyzed aluminum in a solvent at low pressures using one of several tertiary amines. Raman and infrared spectroscopy was performed on the products of these reactions to better understand the structure of the alane amines that are formed, as well as the hydrogenation reactions that take place. A vibrational analysis of the regeneration products performed with Raman and infrared spectroscopy is presented and will help clarify the molecular and vibrational structures of these alane amine adducts.

  8. Thermochemistry of Alane Complexes for Hydrogen Storage: A Theoretical and Experimental Investigation

    PubMed Central

    2011-01-01

    Knowledge of the relative stabilities of alane (AlH3) complexes with electron donors is essential for identifying hydrogen storage materials for vehicular applications that can be regenerated by off-board methods; however, almost no thermodynamic data are available to make this assessment. To fill this gap, we employed the G4(MP2) method to determine heats of formation, entropies, and Gibbs free energies of formation for 38 alane complexes with NH3−nRn (R = Me, Et; n = 0−3), pyridine, pyrazine, triethylenediamine (TEDA), quinuclidine, OH2−nRn (R = Me, Et; n = 0−2), dioxane, and tetrahydrofuran (THF). Monomer, bis, and selected dimer complex geometries were considered. Using these data, we computed the thermodynamics of the key formation and dehydrogenation reactions that would occur during hydrogen delivery and alane regeneration, from which trends in complex stability were identified. These predictions were tested by synthesizing six amine−alane complexes involving trimethylamine, triethylamine, dimethylethylamine, TEDA, quinuclidine, and hexamine and obtaining upper limits of ΔG° for their formation from metallic aluminum. Combining these computational and experimental results, we establish a criterion for complex stability relevant to hydrogen storage that can be used to assess potential ligands prior to attempting synthesis of the alane complex. On the basis of this, we conclude that only a subset of the tertiary amine complexes considered and none of the ether complexes can be successfully formed by direct reaction with aluminum and regenerated in an alane-based hydrogen storage system. PMID:22962624

  9. In memoriam Alan Moorwood

    NASA Astrophysics Data System (ADS)

    de Zeeuw, T.; Leibundgut, B.; Fosbury, R.; D'Odorico, S.

    2011-09-01

    Alan Moorwood died on 18 June 2011 at the age of 66 after a short illness. He had recently retired from ESO as Director of Programmes, having played a leading role in instrumentation for many years. There follows an obituary by Tim de Zeeuw and a joint tribute by three of his long-time ESO colleagues, Bruno Leibundgut, Bob Fosbury and Sandro D'Odorico.

  10. Reaction kinetics for the solid state synthesis of the AlH3/MgCl2 nano-composite by mechanical milling.

    PubMed

    Duan, C W; Hu, L X; Sun, Y; Zhou, H P; Yu, H

    2015-09-14

    The process of mechanical milling has been proved to be a cost-effective way to synthesize the AlH3/MgCl2 nano-composite by using MgH2 and AlCl3 as reagents. However, so far there is no comprehensive knowledge of the kinetics of this process. In an effort to predict the reaction progress and optimize the milling parameters, the kinetics of the synthesis of the AlH3/MgCl2 nano-composite by mechanical milling of MgH2 and AlCl3 is experimentally investigated in the present work. The reaction progress or the transformation fraction upon milling for different times is evaluated using the isothermal hydrogen desorption test of the as-milled samples at 220 °C, which is much lower than the threshold temperature for the de-hydriding of the reagent MgH2 but enough for the de-hydriding of the as-synthesized nano-sized AlH3. The effects of milling parameters on the reaction kinetics as well as the underlying mechanism are discussed by referring to the mechanical energy input intensity, the vial temperature and the Gibbs free energy change for the reaction. Furthermore, it is found that the Johnson-Mehl-Avrami (JMA) model can well describe the kinetics theoretically. By fitting the experimental data with the JMA expression, the theoretical kinetics expressions, the equation parameters, and the activation energy are obtained. PMID:26256935

  11. Computational study of pristine and titanium-doped sodium alanates for hydrogen storage applications

    NASA Astrophysics Data System (ADS)

    Dathar, Gopi Krishna Phani

    The emphasis of this research is to study and elucidate the underlying mechanisms of reversible hydrogen storage in pristine and Ti-doped sodium aluminum hydrides using molecular modeling techniques. An early breakthrough in using complex metal hydrides as hydrogen storage materials is from the research on sodium alanates by Bogdanovic et al., in 1997 reporting reversible hydrogen storage is possible at moderate temperatures and pressures in transition metal doped sodium alanates. Anton reported titanium salts as the best catalysts compared to all other transition metal salts from his further research on transition metal doped sodium alanates. However, a few questions remained unanswered regarding the role of Ti in reversible hydrogen storage of sodium alanates with improved thermodynamics and kinetics of hydrogen desorption. The first question is about the position of transition metal dopants in the sodium aluminum hydride lattice. The position is investigated by identifying the possible sites for titanium dopants in NaAlH4 lattice and studying the structure and dynamics of possible compounds resulting from titanium doping in sodium alanates. The second question is the role of titanium dopants in improved thermodynamics of hydrogen desorption in Ti-doped NaAlH4. Though it is accepted in the literature that formation of TiAl alloys (Ti-Al and TiAl3) is favorable, reaction pathways are not clearly established. Furthermore, the source of aluminum for Ti-Al alloy formation is not clearly understood. The third question in this area is the role of titanium dopants in improved kinetics of hydrogen absorption and desorption in Ti-doped sodium alanates. This study is directed towards addressing the three longstanding questions in this area. Thermodynamic and kinetic pathways for hydrogen desorption in pristine NaAlH4 and formation of Ti-Al alloys in Ti-doped NaAlH 4, are elucidated to understand the underlying mechanisms of hydrogen desorption. Density functional theory

  12. Understanding the role of Ti in reversible hydrogen storage as sodium alanate: a combined experimental and density functional theoretical approach.

    PubMed

    Chaudhuri, Santanu; Graetz, Jason; Ignatov, Alex; Reilly, James J; Muckerman, James T

    2006-09-01

    We report the results of an experimental and theoretical study of hydrogen storage in sodium alanate (NaAlH(4)). Reversible hydrogen storage in this material is dependent on the presence of 2-4% Ti dopant. Our combined study shows that the role of Ti may be linked entirely to Ti-containing active catalytic sites in the metallic Al phase present in the dehydrogenated NaAlH(4). The EXAFS data presented here show that dehydrogenated samples contain a highly disordered distribution of Ti-Al distances with no long-range order beyond the second coordination sphere. We have used density functional theory techniques to calculate the chemical potential of possible Ti arrangements on an Al(001) surface for Ti coverages ranging from 0.125 to 0.5 monolayer (ML) and have identified those that can chemisorb molecular hydrogen via spontaneous or only moderately activated pathways. The chemisorption process exhibits a characteristic nodal symmetry property for the low-barrier sites: the incipient doped surface-H(2) adduct's highest occupied molecular orbital (HOMO) incorporates the sigma antibonding molecular orbital of hydrogen, allowing the transfer of charge density from the surface to dissociate the molecular hydrogen. This work also proposes a plausible mechanism for the transport of an aluminum hydride species back into the NaH lattice that is supported by Car-Parrinello molecular dynamics (CPMD) simulations of the stability and mobility of aluminum clusters (alanes) on Al(001). As an experimental validation of the proposed role of titanium and the subsequent diffusion of alanes, we demonstrate experimentally that AlH(3) reacts with NaH to form NaAlH(4) without any requirement of a catalyst or hydrogen overpressure. PMID:16939263

  13. Roger Alan Myers (1930-2015).

    PubMed

    Phillips, Susan D; Ivey, Allen E

    2016-04-01

    Presents an obituary for Roger Alan Myers, who passed away September 13, 2015, in Stuart, Florida, at age 85. Meyers was a long-time national leader of counseling psychology. (PsycINFO Database Record PMID:27042889

  14. Portrait of Astronaut Alan L. Bean

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Portrait of Astronaut Alan L. Bean, Prime Crew Lunar Module Pilot of the Apollo 12 Lunar Landing Mission, in his space suit minus the helmet. He is standing outside beside a mock-up of the Lunar Lander.

  15. Astronaut Alan Bean shaves while aboard Skylab

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Astronaut Alan L. Bean, Skylab 3 commander, uses battery powered shaver while in the crew quarters of the Skylab space station's Orbital Workshop (OWS) crew quarters. This photograph was taken with a 35mm Nikon camera held by one of Bean's fellow crewmen during the 56.5 day second manned Skylab mission in Earth orbit.

  16. Obituary: Alan D. Fiala (1942-2010)

    NASA Astrophysics Data System (ADS)

    Kaplan, George

    2011-12-01

    Dr. Alan Dale Fiala, astronomer and expert on solar eclipses, died on May 26, 2010 in Arlington, Virginia, of respiratory failure after a brief illness. He was 67. Fiala had been a staff astronomer at the U.S. Naval Observatory in Washington, D.C., for his entire professional career, where he rose from a position as a summer intern to become the Chief of the Nautical Almanac Office, responsible for annual publications for astronomy and navigation that are used the world over. He retired from the observatory in 2000. Although a childhood case of polio affected his mobility for the rest of his life, he seldom let his physical constraints limit his activities, which were many and varied. Alan Fiala was born in Beatrice, Nebraska on November 9, 1942, the middle son of Emil A. ("John") and Lora Marie Fiala. Fiala's father was a postal clerk and Civil Service examiner. Fiala expressed interest in astronomy at a very young age. He contracted polio when he was 9. He graduated from Beatrice High School in 1960 with a straight-A average and went on to study at Carleton College. He received his B.A. summa cum laude after three years, in 1963, with a major in astronomy and minors in physics and mathematics. He was elected to Phi Beta Kappa, Sigma Xi, and Pi Mu Epsilon (mathematics). In 1962, Alan Fiala obtained a job as a summer intern at the Naval Observatory in Washington, working in the Nautical Almanac Office (NAO). He entered the graduate program at Yale University and continued to work summers at the observatory. He received his Ph.D. in 1968, under Gerald Clemence. His dissertation was titled "Determination of the Mass of Jupiter from a Study of the Motion of 57 Mnemosyne." After receiving his doctorate, Fiala became a permanent member of the Naval Observatory staff. Computers were just being introduced there and he participated in the automation of many procedures used to prepare the annual publications of the Nautical Almanac Office. One of his first assignments was

  17. A parallel vectorized implementation of triple excitations in CCSD(T) - Application to the binding energies of the AlH3, AlH2F, AlHF2 and AlF3 dimers

    NASA Technical Reports Server (NTRS)

    Rendell, Alistair P.; Lee, Timothy J.; Komornicki, Andrew

    1991-01-01

    An efficient method for various noniterative estimates of connected triple excitations in coupled-cluster theory is outlined and related to a similar expression occurring in Moller-Plesset perturbation theory. The method is highly vectorized and capable of utilizing multiple processors on a shared-memory machine, leading to computational rates in excess of one billion floating-point operations per second on four processors of a CRAY Y-MP. Using the new procedure, the binding energies of the D(2h) diborane-type dimers of AlH3, AlH2F, AlHF2, and AlF3 have been determined to be 32, 40, 20, and 47 kcal/mol, respectively. For Al2F6, the correlation procedure includes 232 molecular orbitals and over 1.5 x 10 to the 6th single and double coupled-cluster amplitudes, effectively accounting for over 2 x 10 to the 9th connected triple excitations.

  18. Obituary: Alan D. Fiala (1942-2010)

    NASA Astrophysics Data System (ADS)

    Kaplan, George

    2011-12-01

    Dr. Alan Dale Fiala, astronomer and expert on solar eclipses, died on May 26, 2010 in Arlington, Virginia, of respiratory failure after a brief illness. He was 67. Fiala had been a staff astronomer at the U.S. Naval Observatory in Washington, D.C., for his entire professional career, where he rose from a position as a summer intern to become the Chief of the Nautical Almanac Office, responsible for annual publications for astronomy and navigation that are used the world over. He retired from the observatory in 2000. Although a childhood case of polio affected his mobility for the rest of his life, he seldom let his physical constraints limit his activities, which were many and varied. Alan Fiala was born in Beatrice, Nebraska on November 9, 1942, the middle son of Emil A. ("John") and Lora Marie Fiala. Fiala's father was a postal clerk and Civil Service examiner. Fiala expressed interest in astronomy at a very young age. He contracted polio when he was 9. He graduated from Beatrice High School in 1960 with a straight-A average and went on to study at Carleton College. He received his B.A. summa cum laude after three years, in 1963, with a major in astronomy and minors in physics and mathematics. He was elected to Phi Beta Kappa, Sigma Xi, and Pi Mu Epsilon (mathematics). In 1962, Alan Fiala obtained a job as a summer intern at the Naval Observatory in Washington, working in the Nautical Almanac Office (NAO). He entered the graduate program at Yale University and continued to work summers at the observatory. He received his Ph.D. in 1968, under Gerald Clemence. His dissertation was titled "Determination of the Mass of Jupiter from a Study of the Motion of 57 Mnemosyne." After receiving his doctorate, Fiala became a permanent member of the Naval Observatory staff. Computers were just being introduced there and he participated in the automation of many procedures used to prepare the annual publications of the Nautical Almanac Office. One of his first assignments was

  19. Methods for synthesizing alane without the formation of adducts and free of halides

    DOEpatents

    Zidan, Ragaiy; Knight, Douglas A; Dinh, Long V

    2013-02-19

    A process is provided to synthesize an alane without the formation of alane adducts as a precursor. The resulting product is a crystallized .alpha.-alane and is a highly stable product and is free of halides.

  20. David Alan Walker (1928-2012).

    PubMed

    Edwards, Gerald E; Heber, Ulrich

    2012-06-01

    David Alan Walker, Emeritus Professor of Biology, University of Sheffield, UK and Fellow of the Royal Society, died on February 13, 2012. David had a marvelous 60 year career as a scientist, during which he was a researcher, mentor, valued colleague, and a prolific writer in the field of photosynthesis. His career was marked by creative breakthroughs in isolation and analysis of chloroplast metabolism in vitro and simple but valuable technical advances for measurement of photosynthesis in vivo that remain relevant on a global scale to production of crops and biofuels, as well as plant responses to climate change. We include here personal remembrances by the authors (GEE and UH), and by (in alphabetical order): Zoran Cerovic (France), Bob Furbank (Australia), Geoffrey Hind (USA), John Humby (UK), Agu Laisk (Estonia), Peter Lea (UK), Ross Lilley (Australia), Barry Osmond (Australia), Simon Robinson (Australia) and Charles Stirling (UK). PMID:22638915

  1. Remembering James Alan Bassham (1922-2012).

    PubMed

    Govindjee; Bassham, Helen; Bassham, Susan

    2016-04-01

    James Alan Bassham, known to many as Al, was born on November 26, 1922, in Sacramento, California (CA), USA. He died on November 19, 2012, in El Cerrito, CA. To celebrate his life at his 3rd death anniversary, we present here a brief biography, comments on his discoveries, but most importantly, remembrances from family and friends; we remember this wonderful and modest person who had played a major pivotal role in the discoveries that led to what he would like to call the P(hotosynthetic) C(arbon) R(eduction) cycle, known to many as the Calvin Cycle, the Calvin-Benson Cycle, or the Calvin-Benson-Bassham Cycle. Based on a personal request by Bassham himself to one of us (Govindjee), we refrain from including his name in the cycle-in recognition of his many students and associates he would have liked to honor. PMID:26582593

  2. Sodium alanate nanoparticles--linking size to hydrogen storage properties.

    PubMed

    Baldé, Cornelis P; Hereijgers, Bart P C; Bitter, Johannes H; de Jong, Krijn P

    2008-05-28

    Important limitations in the application of light metal hydrides for hydrogen storage are slow kinetics and poor reversibility. To alleviate these problems doping and ball-milling are commonly applied, for NaAlH 4 leading to particle sizes down to 150 nm. By wet-chemical synthesis we have prepared carbon nanofiber-supported NaAlH 4 with discrete particle size ranges of 1-10 microm, 19-30 nm, and 2-10 nm. The hydrogen desorption temperatures and activation energies decreased from 186 degrees C and 116 kJ.mol (-1) for the largest particles to 70 degrees C and 58 kJ.mol (-1) for the smallest particles. In addition, decreasing particle sizes lowered the pressures needed for reloading. This reported size-performance correlation for NaAlH 4 may guide hydrogen storage research for a wide range of nanostructured light (metal) hydrides. PMID:18459778

  3. Astronaut Alan Bean participates in lunar surface simulation

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Astronaut Alan L. Bean, lunar module pilot of the Apollo 12 lunar landing mission, participates in lunar surface simulation training in bldg 29 at the Manned Spacecraft Center. Bean is strapped to a one-sixth gravity simulator.

  4. Astronaut Alan Bean works on Modular Equipment Stowage Assembly

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Astronaut Alan L. Bean, lunar module pilot for the Apollo 12 lunar landing mission, works at the Modular Equipment Stowage Assembly (MESA) on the Apollo 12 Lunar Module during the mission's first extravehicular activity, EVA-1, on November 19, 1969.

  5. Alan Shepard Hits A Golf Ball on the Moon

    NASA Video Gallery

    Apollo 14 Commander and original Mercury astronaut Alan Shepard, the first American to fly in space, tees off on the lunar surface during his 1971 mission, with crewmate Edgar Mitchell watching and...

  6. Alan Shepard in the Rendezvous Docking Simulator

    NASA Technical Reports Server (NTRS)

    1963-01-01

    Astronaut Alan Shepard (right) was one of 14 astronauts, 8 NASA test pilots, and 2 McDonnell test pilots who took part in simulator studies. Shepard flew the simulator on November 14, 1963. A.W. Vogeley wrote: 'Many of the astronauts have flown this simulator in support of the Gemini studies and they, without exception, appreciated the realism of the visual scene. The simulator has also been used in the development of pilot techniques to handle certain jet malfunctions in order that aborts could be avoided. In these situations large attitude changes are sometimes necessary and the false motion cues that were generated due to earth gravity were somewhat objectionable; however, the pilots were readily able to overlook these false motion cues in favor of the visual realism.' Roy F. Brissenden noted that: 'The basic Gemini control studies developed the necessary techniques and demonstrated the ability of human pilots to perform final space docking with the specified Gemini-Agena systems using only visual references. ... Results... showed that trained astronauts can effect the docking with direct acceleration control and even with jet malfunctions as long as good visual conditions exist.... Probably more important than data results was the early confidence that the astronauts themselves gained in their ability to perform the maneuver in the ultimate flight mission.' Shepard commented: 'I had the feeling tonight - a couple of times - that I was actually doing the space mission instead of the simulation. As I said before, I think it is a very good simulation.' Shepard also commented on piloting techniques. Most astronauts arrived at this same preferred technique: Shepard: 'I believe I have developed the preferred technique for these conditions and the technique appeared to me to be best was to come in slightly above the target so that I was able to use the longitudinal marks on the body of the target as a reference, particularly for a lateral translation and, of course, I

  7. Astronaut Alan Shepard using MET during geological training in Mexico

    NASA Technical Reports Server (NTRS)

    1970-01-01

    Astronaut Alan B. Shepard Jr., commander of the Apollo 14 lunar landing mission, takes a piece of equipment from the Modular Equipment Transporter (MET) during geological and lunar surface simulation training training in the Pinacate volcanic area of northwestern Sonora, Mexico. The MET has been nicknamed 'Rickshaw' after its shape and method of propulsion.

  8. ESO Astronomers Emeriti -- Sandro D'Odorico and Alan Moorwood

    NASA Astrophysics Data System (ADS)

    Primas, F.; Casali, M.; Walsh, J.

    2010-09-01

    In May and June 2010, Sandro D'Odorico and Alan Moorwood, both driving forces behind many ESO instruments and very active in research, retired after three decades at ESO. The ESO Director General, Tim de Zeeuw, elevated both to the newly inaugurated position of ESO Astronomer Emeritus. Celebrations on their transition to these esteemed positions were held and are briefly described.

  9. Astronaut Alan Bean holds Special Environmental Sample Container

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Astronaut Alan L. Bean, lunar module pilot for the Apollo 12 lunar landing mission, holds a Special Environmental Sample Container filled with lunar soil collected during the extravehicular activity (EVA) in which Astronauts Charles Conrad Jr., commander, and Bean participated. Connrad, who took this picture, is reflected in the helmet visor of the lunar module pilot.

  10. Astronaut Alan Bean doing acrobatics in OWS dome area

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Astronaut Alan L. Bean, Skylab 3 commander, doing acrobatics in the dome area of the Orbital Workshop (OWS) on the space station cluster in Earth orbit. The dome area is about 22 feet in diameter and 19 feet from top to bottom.

  11. Astronaut Alan Bean deploys Lunar Surface Magnetometer on lunar surface

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Astronaut Alan L. Bean, lunar module pilot, deploys the Lunar Surface Magnetometer (LSM) during the first Apollo 12 extravehicular activity on the Moon. The LSM is a component of the Apollo Lunar Surface Experiments Package (ALSEP). The Lunar Module can be seen in the left background.

  12. Astronaut Alan Bean with subpackages of the ALSEP during EVA

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Astronaut Alan L. Bean, lunar module pilot, traverses with the two subpackages of the Apollo Lunar Surface Experiments Package (ALSEP) during the first Apollo 12 extravehicular activity (EVA). Bean deployed the ALSEP components 300 feet from the Lunar Module (LM). The LM and deployed erectable S-band antenna can be seen in the background.

  13. Critique as Homiletics: A Response to Alan Block

    ERIC Educational Resources Information Center

    Mayes, Clifford; Mayes, Pamela Blackwell; Williams, Ellen

    2004-01-01

    Alan Block's (2004) major criticism of the authors' study revolves around the notion that they have attempted to quantify their students' sense of calling in an existentially inauthentic, spiritually delimiting way. For, as he puts it, "identifications of presence are impossible." The authors cannot accept this pronouncement if only for the simple…

  14. Understanding the Scientific Enterprise: A Conversation with Alan Leshner

    ERIC Educational Resources Information Center

    Perkins-Gough, Deborah

    2007-01-01

    Understanding the nature of science is even more important than mastering its details, says Alan Leshner, Chief Executive Officer of the American Association for the Advancement of Science, in an interview with Educational Leadership. In this article, Leshner discusses the controversy about teaching evolution, and he asserts that demands to…

  15. 40 Years in Applied Linguistics: An Interview with Alan Davies

    ERIC Educational Resources Information Center

    Kunnan, Antony John

    2005-01-01

    This article presents an interview with Professor Alan Davies who was born in Wales, studied at Oxford University and Birmingham University, and taught in Scotland at the University of Edinburgh, completing 40 years this year. Professor Davies has travelled widely to give invited talks and seminars, participate in applied linguistics conferences,…

  16. Why Henry Made It: A Reply to S. Alan Cohen

    ERIC Educational Resources Information Center

    Kleederman, Frances F.

    1977-01-01

    Responds to an article by S. Alan Cohen on oral language deficiency and its relation to reading failure, and concludes that reading achievement and reading failure are largely determined by cognitive and communicative strategies that may be socialized differently in diverse social and ethnic groups. (JM)

  17. Astronaut Owen Garriott trims hair of Astronaut Alan Bean

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Scientist-Astronaut Owen K. Garriott, Skylab 3 science pilot, trims the hair of Astronaut Alan L. Bean, commander, in this on-board photograph from the Skylab Orbital Workshop (OWS). Bean holds a vacuum hose to gather in loose hair.

  18. Astronaut Alan Shepard walks toward MET during first EVA

    NASA Technical Reports Server (NTRS)

    1971-01-01

    Astronaut Alan B. Shepard Jr., foreground, Apollo 14 commander, walks toward the Modularized Equipment Transporter (MET), out of view at right, during the first Apollo 14 extravehicular activity (EVA-1). An EVA checklist is attached to Shepard's left wrist. Astronaut Edgar D. Mitchell, lunar module pilot, is in the background working at a subpackage of the Apollo Lunar Surface Experiments Package (ALSEP). The cylindrical keg-like object directly under Mitchell's extended left hand is the Passive Seismic Experiment (PSE).

  19. Editors' overview for the Alan Turner Memorial volume

    NASA Astrophysics Data System (ADS)

    O'Regan, Hannah J.; Elton, Sarah; Schreve, Danielle

    2014-07-01

    The papers presented here, in this special volume dedicated to the memory of Alan Turner (1947-2012), provide a glimpse of the multi-faceted ways in which the mammalian fossil record can be investigated. The authors of contributions in this Special Issue are by no means an exhaustive list of his international collaborators and colleagues, and indeed, many are not represented here, but the contents cover many of the topics and issues that were of central archaeological and wider Quaternary mammalian interest to Alan. Although the papers are not intended to provide a comprehensive overview of all techniques that can be applied, the set nevertheless reveals a snapshot of the state-of-the-art and of some of the methods that have the potential to bring much more of the past to life. Alan always sought to move beyond the 'stamp-collecting' approach of simply listing which taxa were present at a site, attempting to elucidate what the presence of those animals might mean in terms of palaeoecology. In particular, the span of Alan's career has seen major advances in our understanding of Quaternary mammalian biostratigraphy and palaeobiogeography, the widespread application of novel techniques such as ancient DNA, the development of high-precision geochronology and the discovery of new hominin species. The papers presented here reflect those developments and highlight interdisciplinary approaches, from examination of sediments to careful measurements of the fossils themselves, from modelling the presence of taxa at particular points in the Quaternary to examination of the similarities and differences in fauna within and between sites.

  20. Astronaut Alan Bean assisted with egressing command module after landing

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Astronaut Alan L. Bean, lunar module pilot, is assisted with egressing the Apollo 12 Command Module by a U.S. Navy underwater demolition team swimmer during recovery operations in the Pacific Ocean. Already in the life raft are Astronauts Charles Conrad Jr., commander; and Richard F. Gordon Jr., command module pilot. The Apollo 12 splashdown occured at 2:58 p.m., November 24, 1969 near American Samoa.

  1. Astronaut Alan Bean flies the Astronaut Maneuvering Equipment

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Astronaut Alan L. Bean, Skylab 3 commander, flies the M509 Astronaut Maneuvering Equipment in the forward dome area of the Orbital Workshop (OWS) on the space station cluster in Earth orbit. Bean is strapped in to the back-mounted, hand-controlled Automatically Stabilized Maneuvering Unit (ASMU). This ASMU exerperiment is being done in shirt sleeves. The dome area where the experiment is conducted is about 22 feet in diameter and 19 feet from top to bottom.

  2. Astronaut Alan Bean flies the Astronaut Maneuvering Equipment

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Astronaut Alan L. Bean, Skylab 3 commander, flies the M509 Astronaut Maneuvering Equipment in the foreward dome area of the Orbital Workshop (OWS) on the space station cluster in Earth orbit. Bean is strapped in to the back-mounted, hand-controlled Automatically Stabilized Maneuvering Unit (ASMU). This ASMU exerperiment is being done in shirt sleeves. The dome area where the experiment is conducted is about 22 feet in diameter and 19 feet from top to bottom.

  3. Astronaut Alan Bean flies the Astronaut Maneuvering Equipment

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Astronaut Alan L. Bean, Skylab 3 commander, flies the M509 Astronaut Maneuvering Equipment in the foreward dome area of the Orbital Workshop (OWS) on the space station cluster in Earth orbit. Bean is strapped in to the back-mounted, hand-controlled Automatically Stabilized Maneuvering Unit (ASMU). He is wearing a pressure suit for this run of the M509 experiment, but other ASMU tests are done in shirt sleeves. The dome area where the experiment is conducted is about 22 feet in diameter and 19 feet from top to bottom.

  4. 77 FR 74518 - Alan T. Waterman Award Committee; Notice of Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-14

    ... From the Federal Register Online via the Government Publishing Office NATIONAL SCIENCE FOUNDATION Alan T. Waterman Award Committee; Notice of Meeting In accordance with the Federal Advisory Committee Act (Pub. L. 92- 463, as amended), the National Science Foundation announces the following meeting: Name: Alan T. Waterman Award Committee,...

  5. nanoparticles

    NASA Astrophysics Data System (ADS)

    Andreu-Cabedo, Patricia; Mondragon, Rosa; Hernandez, Leonor; Martinez-Cuenca, Raul; Cabedo, Luis; Julia, J. Enrique

    2014-10-01

    Thermal energy storage (TES) is extremely important in concentrated solar power (CSP) plants since it represents the main difference and advantage of CSP plants with respect to other renewable energy sources such as wind, photovoltaic, etc. CSP represents a low-carbon emission renewable source of energy, and TES allows CSP plants to have energy availability and dispatchability using available industrial technologies. Molten salts are used in CSP plants as a TES material because of their high operational temperature and stability of up to 500°C. Their main drawbacks are their relative poor thermal properties and energy storage density. A simple cost-effective way to improve thermal properties of fluids is to dope them with nanoparticles, thus obtaining the so-called salt-based nanofluids. In this work, solar salt used in CSP plants (60% NaNO3 + 40% KNO3) was doped with silica nanoparticles at different solid mass concentrations (from 0.5% to 2%). Specific heat was measured by means of differential scanning calorimetry (DSC). A maximum increase of 25.03% was found at an optimal concentration of 1 wt.% of nanoparticles. The size distribution of nanoparticle clusters present in the salt at each concentration was evaluated by means of scanning electron microscopy (SEM) and image processing, as well as by means of dynamic light scattering (DLS). The cluster size and the specific surface available depended on the solid content, and a relationship between the specific heat increment and the available particle surface area was obtained. It was proved that the mechanism involved in the specific heat increment is based on a surface phenomenon. Stability of samples was tested for several thermal cycles and thermogravimetric analysis at high temperature was carried out, the samples being stable.

  6. Light metal alanates and amides for reversible hydrogen storage applications

    NASA Astrophysics Data System (ADS)

    Lu, Jun

    Hydrogen is undoubtedly one of the key alternatives to replace petroleum products as a clean energy carrier for both transportation and stationary applications. Although there have been numerous material systems studied as potential candidates for hydrogen storage applications, none of the materials known to date has demonstrated sufficient hydrogen capacity or efficiency in the required operating temperature ranges. There are still considerable opportunities for the discovery of new materials that could lead to advances in science as well as commercial technologies in this area. In this study, two new hydrogen-storage systems, i.e. alanate/amide and LiMgN, are investigated. Firstly, we found that if LiAlH4 and LiNH2 are allowed to react in a proper molar ratio, the LiH that forms as an intermediate product of the dehydrogenation of LiAlH4 can subsequently react with LiNH2 to release H2 at temperatures below 300°C, much lower than that without LiNH2. However, this system is only partially reversible. The difficulty of reversing the reaction is attributed to the irreversibility of the dehydrogenation reaction of LiAlH4 to Li3AlH6. Further experimental results showed that the reversible storage capacity of the combined alanate/amide material system is increased to 7.0 wt% under 300°C, if LiNH2 were reacted with Li3AlH6, instead of LiAlH4, in a 3:1 molar ratio. We also found that the re-formation of Li3AlH 6 depends strongly on the heating rate during the hydrogenation process. To improve the kinetic and thermodynamic properties of the Li-Al-N-H systems, the reaction between Li3AlH6 and Mg(NH2) 2 was studied based on the understanding of the destabilizing effect of amide on alanates. The Li-Al-Mg-N-H system would have better kinetic properties than the Li-Al-N-H system due to the addition of Mg, based on the published research results on the comparison between the Li-Mg-N-H and Li-N-H systems. A reversible 6.2 wt% H2 storage capacity has been demonstrated under the

  7. Sir Alan Sterling Parkes: 10 September 1900 - 17 July 1990.

    PubMed

    Polge, Christopher

    2006-01-01

    Alan Parkes was one of the most influential figures in the field of reproductive biology in the twentieth century. He had a huge impact on its growth and development during that time, and the legacy of his work still remains.His research was highly innovative and original because of his imaginative and inquiring mind, which, coupled with an entrepreneurial bent, led him into several very different fields and into unchartered waters. He played a leading role in the spectacular rise of reproductive endocrinology in Britain in the 1920s and 1930s when the nature and activity of many of the reproductive processes in animals and humans and was an essential factor in the development of methods for their control. Even more pioneering was his research in low-temperature biology in the years after World War II. This was sparked off by the discovery that glycerol had a remarkable property of protecting spermatozoa against damage during freezing and storage at very low temperatures. Far-reaching applications arose from this discovery, especially in the preservation of bull semen, which led to a worldwide revolution in artificial insemination in cattle. Later, many other cells and tissues were also successfully frozen, including red blood cells, ovarian tissue and bone marrow, and a new branch of biological science, which became known as 'cryobiology', was born, Effects of deep hypothermia, including freezing, on whole animals were also investigated at that time. Having successfully launched a new area of science, it was characteristic of Alan Parkes to switch to new fields. First he became interested in the influence of pheromones on mammalian reproduction. Then, resuming a long-standing interest in comparative aspects of reproductive physiology in British wild mammals, he became involved in the work of the Nuffield Unit of Tropical Animal Ecology in Uganda, where similar studies were carried out on African animals. Even after retirement from the academic field, he was for

  8. Astronauts Alan Bean and Charles Conrad on Lunar Surface

    NASA Technical Reports Server (NTRS)

    1969-01-01

    The second manned lunar landing mission, Apollo 12 launched from launch pad 39-A at Kennedy Space Center in Florida on November 14, 1969 via a Saturn Five launch vehicle. The Saturn V vehicle was developed by the Marshall Space Flight Center (MSFC) under the direction of Dr. Wernher von Braun. Aboard Apollo 12 was a crew of three astronauts: Alan L. Bean, pilot of the Lunar Module (LM), Intrepid; Richard Gordon, pilot of the Command Module (CM), Yankee Clipper; and Spacecraft Commander Charles Conrad. The LM, Intrepid, landed astronauts Conrad and Bean on the lunar surface in what's known as the Ocean of Storms while astronaut Richard Gordon piloted the CM, Yankee Clipper, in a parking orbit around the Moon. Their lunar soil activities included the deployment of the Apollo Lunar Surface Experiments Package (ALSEP), finding the unmanned Surveyor 3 that landed on the Moon on April 19, 1967, and collecting 75 pounds (34 kilograms) of rock samples. In this photograph, one of the astronauts on the Moon's surface is holding a container of lunar soil. The other astronaut is seen reflected in his helmet. Apollo 12 safely returned to Earth on November 24, 1969.

  9. How Alan Hirsig plans to play Arco chemical's strong hand

    SciTech Connect

    Hunter, D.

    1993-02-17

    With 1992 net income up 4%, to $195 million. Arco Chemical (Newtown Square, PA) held its own in a year when many of its petrochemical industry peers were mauled again. Arco Chemical president and CEO Alan R. Hirsig talked recently with CW about his growth strategies for the company, and about progress with his Manufacturing Excellence initiative, lauched in the wake of the 1990 Channelview, TX tragedy. Riding on faster growth in the Asia region, Hirsig expects to see Arco's regional sales mix shift in the next three years and sales to grow from 1992's $3.1 billion to $4 billion/year. The foundation for that growth continues to be Arco's core proprietary technology competence for making propylene oxide (PO) with coproduction and tert-butyl alcohol (TBA) - the key methyl tert-butyl ether (MTBE) feedstock, or styrene monomer. Arco claims a 28% share of world MTBE capacity, its 78,500-bbl/day capacity. He cites Jakarta, Bangkok, Mexico City, Milan, Turin, and Athens as examples of major cities where MTBE use in reformulated fuels is getting interest. Given what he views as Europe's traditional 10-year lag on the US in areas like catalytic mufflers and unleaded gasoline, he sees significant prospects in reformulated gasoline in that region in the coming years. Arco is also testing a proprietary TBA-based hydroperoxide in diesel fuels, which improves the cetane number and cleans up exhaust emissions, winning great interest in Tokyo. Also in the fuels area, Hirsig notes interest in ethyl tert-butyl ether production - which Arco launched in the US in December on a commercial scale - in France.

  10. Preparation of polyaniline/sodium alanate hybrid using a spray-drying process

    NASA Astrophysics Data System (ADS)

    Moreira, B. R.; Passador, F. R.; Pessan, L. A.

    2014-05-01

    Nowadays, hydrogen is highly interesting as an energy source, in particular in the automotive field. In fact, hydrogen is attractive as a fuel because it prevents air pollution and greenhouse emissions. One of the main problems with the utilization of hydrogen as a fuel is its on-board storage. The purpouse of this work was to develop a new hybrid material consisting of a polyaniline matrix with sodium alanate (NaAlH4) using a spray-drying process. The polyaniline used for this experiment was synthesized by following a well-established method for the synthesis of the emeraldine base form of polyaniline using dodecylbenzenesulfonic acid as dopant. Micro particles of polyaniline/sodium alanate hybrids with 30 and 50 wt% of sodium alanate were prepared by using a spray-drying technique. Dilute solutions of polyaniline/sodium alanate were first prepared, 10g of the solid materials were mixed with 350 ml of toluene under stirring at room temperature for 24h and the solutions were dried using spray-dryer (Büchi, Switzerland) with 115°C of an inlet temperature. The hybrids were analyzed by differential scanning calorimetry, FT-IR and scanning electron microscopy (SEM). The addition of sodium alanate decreased the glass transition temperature of the hybrids when compared to neat polyaniline. FT-IR spectrum analysis was performed to identify the bonding environment of the synthesized material and was observed that simply physically mixture occurred between polyaniline and sodium alanate. The SEM images of the hybrids showed the formation of microspheres with sodium alanate dispersed in the polymer matrix.

  11. Preparation of polyaniline/sodium alanate hybrid using a spray-drying process

    SciTech Connect

    Moreira, B. R. E-mail: fabiopassador@gmail.com Passador, F. R. E-mail: fabiopassador@gmail.com Pessan, L. A. E-mail: fabiopassador@gmail.com

    2014-05-15

    Nowadays, hydrogen is highly interesting as an energy source, in particular in the automotive field. In fact, hydrogen is attractive as a fuel because it prevents air pollution and greenhouse emissions. One of the main problems with the utilization of hydrogen as a fuel is its on-board storage. The purpouse of this work was to develop a new hybrid material consisting of a polyaniline matrix with sodium alanate (NaAlH{sub 4}) using a spray-drying process. The polyaniline used for this experiment was synthesized by following a well-established method for the synthesis of the emeraldine base form of polyaniline using dodecylbenzenesulfonic acid as dopant. Micro particles of polyaniline/sodium alanate hybrids with 30 and 50 wt% of sodium alanate were prepared by using a spray-drying technique. Dilute solutions of polyaniline/sodium alanate were first prepared, 10g of the solid materials were mixed with 350 ml of toluene under stirring at room temperature for 24h and the solutions were dried using spray-dryer (Büchi, Switzerland) with 115°C of an inlet temperature. The hybrids were analyzed by differential scanning calorimetry, FT-IR and scanning electron microscopy (SEM). The addition of sodium alanate decreased the glass transition temperature of the hybrids when compared to neat polyaniline. FT-IR spectrum analysis was performed to identify the bonding environment of the synthesized material and was observed that simply physically mixture occurred between polyaniline and sodium alanate. The SEM images of the hybrids showed the formation of microspheres with sodium alanate dispersed in the polymer matrix.

  12. LEDs/ALAN-Working To Be Good Neighbors

    NASA Astrophysics Data System (ADS)

    Adams, Robert

    2015-08-01

    ALAN (Artificial Light At Night) and LEDs have recently become major discussion topics in the areas of astronomy, light pollution, endangered species and human health to mention but a few. In years past, MH, LPS and HPS dominated night lighting with LPS and its associated narrow spectrum as the preferred source around observatories and shorelines. LEDs offer the ability to modify the spectrum, realize substantial energy savings and other associated benefits while meeting the requirements of the astronomy community.The primary concern of the different groups relates to blue light content of the LED. For astronomers, the molecular (Raleigh) scattering related to the blue light interferes with certain portions of the spectrum used for deep space studies. The ecologists studying various endangered species find blue and green light can be related to declining leatherback turtle population in certain areas of the world. Other animals ranging from bats to moths and other insects are now being studied to determine the effect of the blue light spectrum on their behavior. The impact of blue light on the human circadian rhythm and vision, especially in the older population, is being extensively studied today.This presentation will discuss the spectral power distribution (SPD) of various light sources, the performance of new LED solutions and how the SPD of these new LED’s can be adapted to address some of the issues raised by various constituencies. A discussion describing why some of the metrics used to describe standard lighting are not adequate for specifying the new LED solutions with the modified spectra will be included.Today, lighting plans and implementation are all too often based on opinions and limited data. The ensuing problems and repercussions make it imperative to collect accurate and thorough information. Data collection is now ongoing using a variety of techniques analyzing the “before” and “after” lighting results from the C of HI LED streetlight

  13. Thermochemistry of Alane Complexes for Hydrogen Storage: A Theoretical and Experimental Investigation

    SciTech Connect

    Wong, B.M.; Graetz, J.; Lacina, D.; Nielsen, I.M.B.; Allendorf, M.D.

    2011-03-30

    Knowledge of the relative stabilities of alane (AlH{sub 3}) complexes with electron donors is essential for identifying hydrogen storage materials for vehicular applications that can be regenerated by off-board methods; however, almost no thermodynamic data are available to make this assessment. To fill this gap, we employed the G4(MP2) method to determine heats of formation, entropies, and Gibbs free energies of formation for 38 alane complexes with NH{sub 3-n}R{sub n} (R = Me, Et; n = 0-3), pyridine, pyrazine, triethylenediamine (TEDA), quinuclidine, OH{sub 2-n}R{sub n} (R = Me, Et; n = 0-2), dioxane, and tetrahydrofuran (THF). Monomer, bis, and selected dimer complex geometries were considered. Using these data, we computed the thermodynamics of the key formation and dehydrogenation reactions that would occur during hydrogen delivery and alane regeneration, from which trends in complex stability were identified. These predictions were tested by synthesizing six amine-alane complexes involving trimethylamine, triethylamine, dimethylethylamine, TEDA, quinuclidine, and hexamine and obtaining upper limits of {Delta}G{sup o} for their formation from metallic aluminum. Combining these computational and experimental results, we establish a criterion for complex stability relevant to hydrogen storage that can be used to assess potential ligands prior to attempting synthesis of the alane complex. On the basis of this, we conclude that only a subset of the tertiary amine complexes considered and none of the ether complexes can be successfully formed by direct reaction with aluminum and regenerated in an alane-based hydrogen storage system.

  14. Presidents' Panel: A Conversation with I. King Jordan, Robert Davila, and T. Alan Hurwitz

    ERIC Educational Resources Information Center

    Greenwald, Brian H.; Jordan, I. King; Davila, Robert; Hurwitz, T. Alan

    2014-01-01

    Former Gallaudet presidents: I. King Jordan and Robert Davila join current president T. Alan Hurwitz on a panel moderated by Brian H. Greenwald as they share their experience leading this institution of higher education and offer insight into the transformative changes brought about by the "Deaf President Now" movement.

  15. A Critical Stance in Language Education: A Reply to Alan Waters

    ERIC Educational Resources Information Center

    Simpson, James

    2009-01-01

    In his recent Forum article on ideology in applied linguistics, Alan Waters (2009) takes up arms against what he perceives as a damaging critical tendency. Ideas about language teaching, he claims, are promoted (e.g. learner centredness) or proscribed (e.g. artificial texts) "on the basis of ideological belief rather than pedagogical value". By…

  16. MA-9 ASTRONAUT GORDON COOPER EXPLAINS CAMERA TO BACKUP PILOT ALAN SHEPARD

    NASA Technical Reports Server (NTRS)

    1963-01-01

    Astronaut L. Gordon Cooper explains the 16MM handheld spacecraft camera to his back-up pilot Astronaut Alan Shepard. The camera designed by J. R. Hereford, McDonnell Aircraft Corp., will be used by Cooper during the MA-9 mission.

  17. Astronaut Alan Bean deploys ALSEP during first Apollo 12 EVA on moon

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Astronaut Alan L. Bean, Apollo 12 lunar module pilot, deploys components of the Apollo Lunar Surface Experiments Package (ALSEP) during the first Apollo 12 extravehicular activity (EVA) on the moon. The photo was made by Astronaut Charles Conrad Jr., Apollo 12 commander, using a 70mm handheld Haselblad camera modified for lunar surface usage.

  18. Astronaut Alan Bean steps from ladder of Lunar Module for EVA

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Astronaut Alan L. Bean, lunar module pilot for the Apollo 12 lunar landing mission, steps from the ladder of the Lunar Module to join Astronaut Charles Conrad Jr., commander, in extravehicular activity on November 19, 1969. Astronaut Ricard F. Gordon Jr., command module pilot, remained with the Command/Service Modules in lunar orbit.

  19. Astronaut Alan Bean looks over data acquisition camera on Skylab trainer

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Astronaut Alan L. Bean, commander for Skylab 3, the second manned Skylab mission, looks over the data acquisition camera mounted on the water tank in the upper level of the Orbital Workshop (OWS) one-G trainer at the Manned Spacecraft Center (MSC).

  20. Challenging the Status Quo: Alan Pifer and Higher Education Reform in Colonial Nigeria

    ERIC Educational Resources Information Center

    Anyanwu, Ogechi E.

    2013-01-01

    The historiography of higher education in Nigeria has not fully accounted for Alan Pifer's crucial contributions in reforming the elitist British higher education tradition in colonial Nigeria. Through qualitative analysis of mostly primary sources acquired from the Rare Book and Manuscript Library in Columbia University, this article argues that…

  1. Astronaut Alan Bean reads data from book while holding teleprinter tape

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Astronaut Alan L. Bean, Skylab 3 commander, reads data from book in his right hand while holding teleprinter tape in his left hand, in the ward room of the Skylab space station's Orbital Workshop (OWS) crew quarters. This photograph was taken with a 35mm Nikon camera held by one of Bean's fellow crewmen during the 56.5 day second manned Skylab mission in Earth orbit.

  2. Hydrogen release properties of lithium alanate for application to fuel cell propulsion systems

    NASA Astrophysics Data System (ADS)

    Corbo, P.; Migliardini, F.; Veneri, O.

    In this paper the results of an experimental study on LiAlH 4 (lithium alanate) as hydrogen source for fuel cell propulsion systems are reported. The compound examined in this work was selected as reference material for light metal hydrides, because of its high hydrogen content (10.5 wt.%) and interesting desorption kinetic properties at moderate temperatures. Thermal dynamic and kinetic of hydrogen release from this hydride were investigated using a fixed bed reactor to evaluate the effect of heating procedure, carrier gas flow rate and sample form. The aim of this study was to characterize the lithium alanate decomposition through the reaction steps leading to the formation of Li 3AlH 6 and LiH. A hydrogen tank was designed and realized to contain pellets of lithium alanate as feeding for a fuel cell propulsion system based on a 2-kW Polymeric Electrolyte Fuel Cell (PEFC) stack. The fuel cell system was integrated into the power train comprising DC-DC converter, energy storage systems and electric drive for moped applications (3 kW). The experiments on the power train were conducted on a test bench able to simulate the vehicle behaviour and road characteristics on specific driving cycles. In particular the efficiencies of individual components and overall power train were analyzed evidencing the energy requirements of the hydrogen storage material.

  3. Genome Sequences of Mycobacteriophages AlanGrant, Baee, Corofin, OrangeOswald, and Vincenzo, New Members of Cluster B

    PubMed Central

    Carbonara, Maria E.; Cioffi, Hanna M.; Cruz, Tyler; Dang, Brian Q.; Doyle, Alexander N.; Fan, Olivia H.; Gallagher, Molly; Gentile, Gabrielle M.; German, Brian A.; Farrell, Margaret E.; Gerwig, Madeline; Hunter, Kelsey L.; Lefever, Virginia E.; Marfisi, Nicole A.; McDonnell, Jill E.; Monga, Jappmann K.; Quiroz, Kevin G.; Pong, Alexandra C.; Rimple, Patrick A.; Situ, Michelle; Sohnen, Peri C.; Stockinger, Annmarie N.; Thompson, Paige K.; Torchio, Nicole M.; Toner, Chelsea L.; Ulbrich, Megan C.; Vohra, Neelam I.; Zakir, Aala; Adkins, Nancy L.; Brown, Bryony R.; Churilla, Bryce M.; Kramer, Zachary J.; Lapin, Jonathan S.; Montgomery, Matthew T.; Prout, Ashley K.; Grubb, Sarah R.; Warner, Marcie H.; Bowman, Charles A.; Russell, Daniel A.; Hatfull, Graham F.

    2015-01-01

    AlanGrant, Baee, Corofin, OrangeOswald, and Vincenzo are newly isolated phages of Mycobacterium smegmatis mc2155 discovered in Pittsburgh, Pennsylvania, USA. All five phages share nucleotide similarity with cluster B mycobacteriophages but span considerable diversity with Corofin and OrangeOswald in subcluster B3, AlanGrant and Vincenzo in subcluster B4, and Baee in subcluster B5. PMID:26089409

  4. Genome Sequences of Mycobacteriophages AlanGrant, Baee, Corofin, OrangeOswald, and Vincenzo, New Members of Cluster B.

    PubMed

    Pope, Welkin H; Carbonara, Maria E; Cioffi, Hanna M; Cruz, Tyler; Dang, Brian Q; Doyle, Alexander N; Fan, Olivia H; Gallagher, Molly; Gentile, Gabrielle M; German, Brian A; Farrell, Margaret E; Gerwig, Madeline; Hunter, Kelsey L; Lefever, Virginia E; Marfisi, Nicole A; McDonnell, Jill E; Monga, Jappmann K; Quiroz, Kevin G; Pong, Alexandra C; Rimple, Patrick A; Situ, Michelle; Sohnen, Peri C; Stockinger, Annmarie N; Thompson, Paige K; Torchio, Nicole M; Toner, Chelsea L; Ulbrich, Megan C; Vohra, Neelam I; Zakir, Aala; Adkins, Nancy L; Brown, Bryony R; Churilla, Bryce M; Kramer, Zachary J; Lapin, Jonathan S; Montgomery, Matthew T; Prout, Ashley K; Grubb, Sarah R; Warner, Marcie H; Bowman, Charles A; Russell, Daniel A; Hatfull, Graham F

    2015-01-01

    AlanGrant, Baee, Corofin, OrangeOswald, and Vincenzo are newly isolated phages of Mycobacterium smegmatis mc(2)155 discovered in Pittsburgh, Pennsylvania, USA. All five phages share nucleotide similarity with cluster B mycobacteriophages but span considerable diversity with Corofin and OrangeOswald in subcluster B3, AlanGrant and Vincenzo in subcluster B4, and Baee in subcluster B5. PMID:26089409

  5. Astronaut Alan Bean flies the Astronaut Maneuvering Equipment in the OWS

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Astronaut Alan L. Bean, Skylab 3 commander, flies the M509 Astronaut Maneuvering Equipment, as seen in this photographic reproduction taken from a television transmission made by a color television camera in the Orbital Workshop (OWS) of the Skylab space station in Earth orbit. Bean is strapped into the back-mounted, hand-controlled Automatically stabilized Maneuvering Unit (ASMU). The M509 exercise was in the forward dome area of the OWS. THe dome area is about 22 feet in diameter and 19 feet form top to bottom.

  6. Professor Alan Turner (1947-2012). Specialist in Miocene-Pleistocene Carnivora, particularly Felidae and Hyaenidae and their palaeoecology

    NASA Astrophysics Data System (ADS)

    O'Regan, Hannah; Turner, Adam; Antón, Mauricio

    2014-07-01

    Alan first trained as a telecom engineer, working for the GPO (General Post Office) which later became British Telecom. He never forgot this early training and was fascinated by how things worked - always happy to take something apart and fix it (although his attempt to close a large plate glass window with a geological hammer was not one of his successes). Following a few years as an engineer, he went to Sheffield University to study archaeology as a mature student in 1973. At this time Sheffield was a hotbed of prehistory with Graeme Barker, Robin Dennell and many others contributing to a truly research-led degree (with tutorials in the pub (well, it was the 1970s)) (Fig. 1). Alan's interest in bones developed at this time, and having graduated in 1976 he went on to take a PhD, supervised by Robin Dennell, on "Aspects of the palaeoecology of large predators, including man, during the British Upper Pleistocene, with particular emphasis on predator-prey relationships" which resulted in a life-long interest in the Carnivora and particularly hyaenas. Following his PhD, Alan moved to the Environmental Archaeology Unit at York to undertake a Science Research Council project on the morphometrics of domestic cattle and pigs from Coppergate and other major urban excavations in the city. Faced with a lot of measurements and statistics, Alan retained his interest in the animals themselves. The project also confirmed to Alan that prehistory was his metier, rather than the historic periods. Former York colleagues still fondly recall Alan's dry wit, and the day that he successfully put the irritating lab telephone beyond use with no externally visible trace of damage.

  7. Anisotropic storage medium development in a full-scale, sodium alanate-based, hydrogen storage system

    DOE PAGESBeta

    Jorgensen, Scott W.; Johnson, Terry A.; Payzant, E. Andrew; Bilheux, Hassina Z.

    2016-06-11

    Deuterium desorption in an automotive-scale hydrogen storage tube was studied in-situ using neutron diffraction. Gradients in the concentration of the various alanate phases were observed along the length of the tube but no significant radial anisotropy was present. In addition, neutron radiography and computed tomography showed large scale cracks and density fluctuations, confirming the presence of these structures in an undisturbed storage system. These results demonstrate that large scale storage structures are not uniform even after many absorption/desorption cycles and that movement of gaseous hydrogen cannot be properly modeled by a simple porous bed model. In addition, the evidence indicatesmore » that there is slow transformation of species at one end of the tube indicating loss of catalyst functionality. These observations explain the unusually fast movement of hydrogen in a full scale system and shows that loss of capacity is not occurring uniformly in this type of hydrogen-storage system.« less

  8. Reducing the Harms of College Student Drinking: How Alan Marlatt Changed Approaches, Outcomes, and the Field

    PubMed Central

    Kilmer, Jason R.; Palmer, Rebekka S.; Cronce, Jessica M.; Logan, Diane E.

    2015-01-01

    In this article, we discuss Alan Marlatt’s contributions to the prevention and reduction of alcohol-related harms among college students. We consider Alan’s early research that later led to the development and evaluation of college student drinking programs, and examine Alan’s impact, both directly and indirectly through those he mentored and trained, as a scientist-practitioner. We review the recognition of the efficacy of Alan’s programs, including the Alcohol Skills Training Program (ASTP) and Brief Alcohol Screening and Intervention for College Students (BASICS), in addition to extensions of these interventions in more recent studies. Finally, we discuss how Alan’s work influences interventions with college student drinkers today, and how future directions will continue to be informed by his vision and values. PMID:25774117

  9. Growth of high quality AlGaAs by metalorganic molecular beam epitaxy using trimethylamine alane

    NASA Astrophysics Data System (ADS)

    Abernathy, C. R.; Jordan, A. S.; Pearton, S. J.; Hobson, W. S.; Bohling, D. A.; Muhr, G. T.

    1990-06-01

    AlGaAs grown by metalorganic molecular beam epitaxy (MOMBE) has been problematic due to oxygen and carbon contamination, particularly when triethylaluminum (TEAl) has been used as the aluminum source. Consequently, we have investigated trimethylamine alane (TMAAl) as a potential replacement for the conventional metalorganic Al sources. AlGaAs films with excellent structural and optical properties have been grown with this source. Photoluminescence intensities from AlGaAs grown by MOMBE at 500 °C using TMAAl are comparable to those from material grown by metalorganic chemical vapor deposition at 675 °C using triethylaluminum (TMAl). Carbon and oxygen levels in MOMBE-grown AlGaAs are drastically reduced in comparison to similar films grown with TEAl.

  10. Anisotropic Storage Medium Development in a Full-Scale, Sodium Alanate-Based, Hydrogen Storage System

    SciTech Connect

    Jorgensen, Scott W; Johnson, Terry A; Payzant, E Andrew; Bilheux, Hassina Z

    2016-01-01

    Deuterium desorption in an automotive-scale hydrogen storage tube was studied in-situ using neutron diffraction. Gradients in the concentration of the various alanate phases were observed along the length of the tube but no significant radial anisotropy was present. In addition, neutron radiography and computed tomography showed large scale cracks and density fluctuations, confirming the presence of these structures in an undisturbed storage system. These results demonstrate that large scale storage structures are not uniform even after many absorption/desorption cycles and that movement of gaseous hydrogen cannot be properly modeled by a simple porous bed model. Furthermore, the evidence indicates that there is slow transformation of species at one end of the tube indicating loss of catalyst functionality. These observations explain the unusually fast movement of hydrogen in a full scale system and shows that loss of capacity is not occurring uniformly in this type of hydrogen-storage system.

  11. 77 FR 62238 - Alan B. Miller and Universal Health Services; Analysis of Agreement Containing Consent Orders To...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-12

    ... Alan B. Miller and Universal Health Services; Analysis of Agreement Containing Consent Orders To Aid... practices or unfair methods of competition. The attached Analysis to Aid Public Comment describes both the... following Analysis to Aid Public Comment describes the terms of the consent agreement, and the...

  12. Alan Thomas and the Canadian Association for Adult Education, 1961-1970. Occasional Papers in Continuing Education, Number 24.

    ERIC Educational Resources Information Center

    Selman, Gordon R.

    Alan Thomas' vision of a learning society and its implications for public policy and adult education in Canada were the driving forces in the Canadian Association for Adult Education (CAAE) for the nine years of his directorship. The most distinctive and important idea that he contributed to the field in the 1960s was that the basic concept must…

  13. Discovering the Optimal Route for Alane Synthesis on Ti doped Al Surfaces Using Density Functional Theory Based Kinetic Monte Carlo Methods

    NASA Astrophysics Data System (ADS)

    Karim, Altaf; Muckerman, James T.

    2010-03-01

    Issues such as catalytic dissociation of hydrogen and the mobility of alane species on Ti-doped Al surfaces are major challenges in the synthesis of aluminum hydride. Our recently developed modeling framework (DFT-based KMC simulation) enabled us to study the steady-state conditions of dissociative adsorption of hydrogen, its diffusion, and its reaction with Al adatoms leading to the formation of alane species on Ti-doped Al surfaces. Our studies show that the doping of Ti atoms in the top layer of Al surfaces significantly reduces the mobility of alane species. On the other hand, the doping of Ti atoms beneath the top layer of Al surfaces enhances the mobility of alane species. The arrangement of dopant Ti atoms in different layers not only affects the diffusion barriers of alane species but it also affects hydrogen dissociation barriers when Ti-Ti pairs are arranged in different ways in the top layer. Using our theoretical methods, we identified a few configurations of dopant Ti atoms having lower barriers for alane diffusion and hydrogen dissociation. Further, we discovered the optimal values of Ti concentration, temperature, and pressure under which the rate of alane formation is maximized.

  14. The Society of Brains: How Alan Turing and Marvin Minsky Were Both Right

    NASA Astrophysics Data System (ADS)

    Struzik, Zbigniew R.

    2015-04-01

    In his well-known prediction, Alan Turing stated that computer intelligence would surpass human intelligence by the year 2000. Although the Turing Test, as it became known, was devised to be played by one human against one computer, this is not a fair setup. Every human is a part of a social network, and a fairer comparison would be a contest between one human at the console and a network of computers behind the console. Around the year 2000, the number of web pages on the WWW overtook the number of neurons in the human brain. But these websites would be of little use without the ability to search for knowledge. By the year 2000 Google Inc. had become the search engine of choice, and the WWW became an intelligent entity. This was not without good reason. The basis for the search engine was the analysis of the ’network of knowledge’. The PageRank algorithm, linking information on the web according to the hierarchy of ‘link popularity’, continues to provide the basis for all of Google's web search tools. While PageRank was developed by Larry Page and Sergey Brin in 1996 as part of a research project about a new kind of search engine, PageRank is in its essence the key to representing and using static knowledge in an emergent intelligent system. Here I argue that Alan Turing was right, as hybrid human-computer internet machines have already surpassed our individual intelligence - this was done around the year 2000 by the Internet - the socially-minded, human-computer hybrid Homo computabilis-socialis. Ironically, the Internet's intelligence also emerged to a large extent from ‘exploiting’ humans - the key to the emergence of machine intelligence has been discussed by Marvin Minsky in his work on the foundations of intelligence through interacting agents’ knowledge. As a consequence, a decade and a half decade into the 21st century, we appear to be much better equipped to tackle the problem of the social origins of humanity - in particular thanks to the

  15. Ab initio study on the electronic structure and vibration modes of alkali and alkaline-earth amides and alanates

    NASA Astrophysics Data System (ADS)

    Tsumuraya, Takao; Shishidou, Tatsuya; Oguchi, Tamio

    2009-05-01

    We study the electronic structure and vibrational modes of several amides M(NH2)n and alanates M(AlH4)n (M = K, Na, Li, Ca and Mg), focusing on the role of cation states. Calculated breathing stretching vibration modes for these compounds are compared with measured infrared and Raman spectra. In the amides, we find a significant tendency such that the breathing mode frequencies and the structural parameters of NH2 vary in accordance with the ionization energy of cation. The tendency may be explained by the strength in hybridization between cation orbitals and molecular orbitals of (NH2)-. The microscopic mechanism of correlations between the vibration frequencies and structural parameters is elucidated in relation to the electronic structure. A possible similar tendency in the alanates is also discussed.

  16. From Mercury to Apollo: astronaut Alan Shepard reflects on life support and other space issues [interview by Winston Huff].

    PubMed

    Shepard, A

    1995-01-01

    Alan Shepard was one of the original Mercury astronauts. He became the first American in space on May 5, 1961, in the Freedom 7 capsule, during a 15 minute suborbital trip reaching 115 miles altitude and 302 miles down the Atlantic tracking range. Grounded by an inner ear problem, he served as Chief of the Astronaut Office for several years. After an operation to correct the problem, he commanded the Apollo 14 moon mission in 1971. He retired as a Rear Admiral in 1974. Here, Alan Shepard offers his views on life support comedies and tragedies, going back to the moon, future drivers of the manned space flight program, the benefits of the space program, joint NASA and Russia missions, how his NASA experience affected his personal life, and the profitability of working with NASA. PMID:11538588

  17. Reactions of organyl and silyl alanes with 1,3,4,5,6-pentamethyl-2-aminoborazine.

    PubMed

    Fan, Maomin; Duesler, Eileen N; Nöth, Heinrich; Paine, Robert T

    2010-03-15

    The reactions of (Me(3)Si)(3)Al, Me(3)Al, Et(3)Al, and i-Bu(3)Al with 1,3,4,5,6-pentamethyl-2-aminoborazine have been examined. An amine alane adduct (Me(3)Si)(3)Al.NH(2)B(3)(Me)(2)N(3)Me(3) (1) and several elimination products [(Me(3)Si)(2)AlN(H)B(3)(Me)(2)N(3)Me(3)](2) (2), [(Me(3)SiAl)(4)(Me(3)SiN)(3)NH] (3), [Me(2)AlN(H) B(3)(Me)(2)N(3)Me(3)](2) (4), [Et(2)AlN(H) B(3)(Me)(2)N(3)Me(3)](2) (5), and [i-Bu(2)AlN(H) B(3)(Me)(2)N(3)Me(3)](2) (6) have been isolated. Compounds 1, 2, 4-6 have been spectroscopically characterized, and single crystal X-ray diffraction structure determinations have been completed for 1-4 and 6. The molecular chemistry provides insight into the reaction of Me(3)Al and 1,3,5-N-trimethyl-2,4,6-B-triaminoborazine that, upon pyrolysis, produces AlN/BN composite ceramic materials. PMID:20158196

  18. Functional anion concept: effect of fluorine anion on hydrogen storage of sodium alanate.

    PubMed

    Yin, Li-Chang; Wang, Ping; Kang, Xiang-Dong; Sun, Cheng-Hua; Cheng, Hui-Ming

    2007-03-28

    Doping NaAlH(4) with Ti-catalyst has produced a promising hydrogen storage system that can be reversibly operated at moderate temperature conditions. Of the various dopant precursors, TiCl(3) was well recognized due to its pronounced catalytic effect on the reversible dehydrogenation processes of sodium aluminium hydrides. Quite recently we experimentally found that TiF(3) was even better than TiCl(3) in terms of the critical hydrogen storage properties of the doped hydrides, in particular the dehydriding performance at Na(3)AlH(6)/NaH + Al step at moderate temperature. We present here the DFT calculation results of the TiF(3) or TiCl(3) doped Na(3)AlH(6). Our computational studies have demonstrated that F(-) and Cl(-) anions differ substantially from each other with regard to the state and function in the doped sodium aluminium hydride. In great contrast to the case of chloride doping where Cl(-) anion constitutes the "dead weight" NaCl, the fluoride doping results in a substitution of H(-) by F(-) anion in the hydride lattice and accordingly, a favorable thermodynamics adjustment. These results well explain the observed dehydriding performance associated with TiF(3)/TiCl(3)-doping. More significantly, the coupled computational and experimental efforts allow us to put forward a "functional anion" concept. This renews the current mechanism understanding in the catalytically enhanced sodium alanate. PMID:17356758

  19. Developmental and environmental influences on physiology and behavior--2014 Alan N. Epstein Research Award.

    PubMed

    Tamashiro, Kellie L K

    2015-12-01

    Environmental factors acting during development of an individual may influence future health and disease susceptibility. Stressors, including altered diet, psychosocial stress, and immune challenge, during gestation can have negative consequences on the intrauterine environment and increase disease susceptibility of the developing fetus. The long-term effects on offspring have been observed in humans and include greater susceptibility to psychiatric disease, such as depression and anxiety disorders, and adverse metabolic conditions including obesity, diabetes and cardiovascular disease. Studies in my laboratory use rodent models and incorporate a multilevel approach to determine the behavioral, physiological, and neurobiological correlates of disease development as a consequence of early life stressors. The road I took in developing this research program was a rather circuitous one and navigating that path would not have been possible without the many mentors, colleagues, fellows and students who provided critical support. Although my name appears on the plaque of the Alan N. Epstein Research Award, I share this with all those I had the privilege of working with along that road, as briefly summarized in this article. PMID:26291266

  20. Neuronal Remodeling During Metamorphosis Is Regulated by the alan shepard (shep) Gene in Drosophila melanogaster

    PubMed Central

    Chen, Dahong; Qu, Chunjing; Bjorum, Sonia M.; Beckingham, Kathleen M.; Hewes, Randall S.

    2014-01-01

    Peptidergic neurons are a group of neuronal cells that synthesize and secrete peptides to regulate a variety of biological processes. To identify genes controlling the development and function of peptidergic neurons, we conducted a screen of 545 splice-trap lines and identified 28 loci that drove expression in peptidergic neurons when crossed to a GFP reporter transgene. Among these lines, an insertion in the alan shepard (shep) gene drove expression specifically in most peptidergic neurons. shep transcripts and SHEP proteins were detected primarily and broadly in the central nervous system (CNS) in embryos, and this expression continued into the adult stage. Loss of shep resulted in late pupal lethality, reduced adult life span, wing expansion defects, uncoordinated adult locomotor activities, rejection of males by virgin females, and reduced neuropil area and reduced levels of multiple presynaptic markers throughout the adult CNS. Examination of the bursicon neurons in shep mutant pharate adults revealed smaller somata and fewer axonal branches and boutons, and all of these cellular phenotypes were fully rescued by expression of the most abundant wild-type shep isoform. In contrast to shep mutant animals at the pharate adult stage, shep mutant larvae displayed normal bursicon neuron morphologies. Similarly, shep mutant adults were uncoordinated and weak, while shep mutant larvae displayed largely, although not entirely, normal locomotor behavior. Thus, shep played an important role in the metamorphic development of many neurons. PMID:24931409

  1. The feasibility of using trimethylamine alane as an Al precursor for MOMBE

    NASA Astrophysics Data System (ADS)

    Abernathy, C. R.; Jordan, A. S.; Pearton, S. J.; Ren, F.; Baiocchi, F.; Bohling, D. A.; Muhr, G. T.

    1991-02-01

    The growth of III-V Al-containing epitaxial structures by MOMBE has proven difficult due to the excessive oxygen and carbon contamination introduced by the Al source. Triethylaluminum (TEAl), the most commonly used precursor, produces unacceptable levels of both impurities in AlGaAs grown by MOMBE. We have grown AlGaAs films with excellent structural and optical properties using a novel source, trimethylamine alane (TMAAl). Photoluminescence intensities from AlGaAs grown by MOMBE at 500δC with TMAAl are comparable to those from material grown by MOCVD at 675δC using trimethylaluminum. In addition, carbon and oxygen levels in AlGaAs, as detected by SIMS, are drastically reduced in comparison to similar films produced with TEAl. We shall also discuss the effects of growth temperature and Al content on carbon and oxygen incorporation as well as crystallinity and provide preliminary device results on GaAs/AlGaAs HBTs prepared by the MOMBE technique.

  2. First-principles Study on the Vibration Modes and Electronic Structure of Alkali and Alkaline-earth Amides and Alanates

    NASA Astrophysics Data System (ADS)

    Tsumuraya, Takao; Shishidou, Tatsuya; Oguchi, Tamio

    2009-03-01

    Light alkaline and alkaline-earth metal hydrides such as amides M(NH2)n and alanates M(AlH4)n (M=K, Na, Li, Ca, and Mg) have attracted a growing interest as reversible hydrogen storage materials recently because of their innately high hydrogen contents. [1, 2] We study the electronic structure of the amides and alanates with different cations, focusing on the role of cation states from first-principles calculations based on the all-electron FLAPW method. Calculated breathing stretch vibration modes for these compounds are compared with measured infrared and Raman spectra. In the amides, we find a significant tendency such that the breathing stretch vibration frequencies and the structural parameters of NH2 vary in accordance with the ionization energy of cation, which may be explained by the strength in hybridization between cation orbitals and molecular orbitals of (NH2)^-. We elucidate the microscopic mechanism of correlations between the breathing stretch vibration frequencies of N-H and structural parameters by analyzing the calculated electronic structure from a view point of the molecular-orbitals. A similar tendency in the alanates is also discussed. [1] P. Chen, Z. Xiong, J. Luo, J. Lin and K.L. Tan, Nature 420, 302 (2002). [2] B. Bogdanovi and M. Schwickardi, J. Alloys Compd. 253-254, 1 (1997).

  3. Understanding the Role of Ti in Reversible Hydrogen Storage as Sodium Alanate: A Combined Experimental and Density Functional Theoretical Approach

    SciTech Connect

    Chaudhuri,S.; Graetz, J.; Ignatov, A.; Reilly, J.; Muckerman, J.

    2006-01-01

    We report the results of an experimental and theoretical study of hydrogen storage in sodium alanate (NaAlH{sub 4}). Reversible hydrogen storage in this material is dependent on the presence of 2-4% Ti dopant. Our combined study shows that the role of Ti may be linked entirely to Ti-containing active catalytic sites in the metallic Al phase present in the dehydrogenated NaAlH{sub 4}. The EXAFS data presented here show that dehydrogenated samples contain a highly disordered distribution of Ti-Al distances with no long-range order beyond the second coordination sphere. We have used density functional theory techniques to calculate the chemical potential of possible Ti arrangements on an Al(001) surface for Ti coverages ranging from 0.125 to 0.5 monolayer (ML) and have identified those that can chemisorb molecular hydrogen via spontaneous or only moderately activated pathways. The chemisorption process exhibits a characteristic nodal symmetry property for the low-barrier sites: the incipient doped surface-H2 adduct's highest occupied molecular orbital (HOMO) incorporates the {sigma}* antibonding molecular orbital of hydrogen, allowing the transfer of charge density from the surface to dissociate the molecular hydrogen. This work also proposes a plausible mechanism for the transport of an aluminum hydride species back into the NaH lattice that is supported by Car-Parrinello molecular dynamics (CPMD) simulations of the stability and mobility of aluminum clusters (alanes) on Al(001). As an experimental validation of the proposed role of titanium and the subsequent diffusion of alanes, we demonstrate experimentally that AlH{sub 3} reacts with NaH to form NaAlH{sub 4} without any requirement of a catalyst or hydrogen overpressure.

  4. Materials Data on AlH3 (SG:167) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  5. Radiolarians, foraminifers, and biostratigraphy of the Coniacian-Campanian deposits of the Alan-Kyr Section, Crimean Mountains

    NASA Astrophysics Data System (ADS)

    Bragina, L. G.; Beniamovsky, V. N.; Kopaevich, L. F.

    2016-01-01

    Data on the distribution of radiolarians and planktonic and benthic foraminifers are obtained for the first time from the Alan-Kyr Section (Coniacian-Campanian), in the central regions of the Crimean Mountains. Radiolarian biostrata, previously established from Ak-Kaya Mountain (central regions of the Crimean Mountains) were traced: Alievium praegallowayi-Crucella plana (upper Coniacian-lower Santonian), Alievium gallowayi-Crucella espartoensis (upper Santonian without the topmost part), and Dictyocephalus (Dictyocryphalus) (?) legumen-Spongosaturninus parvulus (upper part of the upper Santonian). Radiolarians from the Santonian-Campanian boundary beds of the Crimean Mountains are studied for the first time, and Prunobrachium sp. ex gr. crassum-Diacanthocapsa acanthica Beds (uppermost Santonian-lower Campanian) are recognized. Bolivinoides strigillatus Beds (upper Santonian) and Stensioeina pommerana-Anomalinoides (?) insignis Beds (upper part of the upper Santonian-lower part of the lower Campanian) are recognized. Eouvigerina aspera denticulocarinata Beds (middle and upper parts of the lower Campanian) and Angulogavelinella gracilis Beds (upper part of the upper Campanian are recognized on the basis of benthic foraminifers. These beds correspond to the synchronous biostrata of the East European Platform and Mangyshlak. Marginotruncana coronata- Concavatotruncana concavata Beds (Coniacian-upper Santonian), Globotruncanita elevata Beds (terminal Santonian), and Globotruncana arca Beds (lower Campanian) are recognized on the basis of planktonic foraminifers. Radiolarian and planktonic and benthic foraminiferal data agree with one another. The position of the Santonian-Campanian boundary in the Alan-Kyr Section, which is located stratigraphically above the levels of the latest occurrence of Concavatotruncana concavata and representatives of the genus Marginotruncana, is refined, i.e., at the level of the first appearance of Globotruncana arca. A gap in the Middle

  6. The reactivity of sodium alanates with O[2], H[2]O, and CO[2] : an investigation of complex metal hydride contamination in the context of automotive systems.

    SciTech Connect

    Dedrick, Daniel E.; Bradshaw, Robert W.; Behrens, Richard, Jr.

    2007-08-01

    Safe and efficient hydrogen storage is a significant challenge inhibiting the use of hydrogen as a primary energy carrier. Although energy storage performance properties are critical to the success of solid-state hydrogen storage systems, operator and user safety is of highest importance when designing and implementing consumer products. As researchers are now integrating high energy density solid materials into hydrogen storage systems, quantification of the hazards associated with the operation and handling of these materials becomes imperative. The experimental effort presented in this paper focuses on identifying the hazards associated with producing, storing, and handling sodium alanates, and thus allowing for the development and implementation of hazard mitigation procedures. The chemical changes of sodium alanates associated with exposure to oxygen and water vapor have been characterized by thermal decomposition analysis using simultaneous thermogravimetric modulated beam mass spectrometry (STMBMS) and X-ray diffraction methods. Partial oxidation of sodium alanates, an alkali metal complex hydride, results in destabilization of the remaining hydrogen-containing material. At temperatures below 70 C, reaction of sodium alanate with water generates potentially combustible mixtures of H{sub 2} and O{sub 2}. In addition to identifying the reaction hazards associated with the oxidation of alkali-metal containing complex hydrides, potential treatment methods are identified that chemically stabilize the oxidized material and reduce the hazard associated with handling the contaminated metal hydrides.

  7. Towards understanding a mechanism for reversible hydrogen storage: theoretical study of transition metal catalysed dehydrogenation of sodium alanate.

    PubMed

    Ljubić, Ivan; Clary, David C

    2010-04-28

    On the basis of density functional theory and coupled-cluster CCSD(T) calculations we propose a mechanism of the dehydrogenation of transition metal doped sodium alanate. Insertion of two early 3d-transition metals, scandium and titanium, both of which are promising catalysts for reversible hydrogen storage in light metal hydrides, is compared. The mechanism is deduced from studies on the decomposition of a model system consisting of one transition metal atom and two NaAlH(4) units. Subsequently, the significance of such minimal cluster model systems to the real materials is tested by embedding the systems into the surface of the NaAlH(4) crystal. It is found that the dehydrogenation proceeds via breaking of the bridge H-Al bond and consequent formation of intermediate coordination compounds in which the H(2) molecule is side-on (eta(2)-) bonded to the transition metal centre. The total barrier to the H(2) release is thus dependent upon both the strength of the Al-H bond to be broken and the depth of the coordinative potential. The analogous mechanism applies for the recognized three successive dehydrogenation steps. The gas-phase model structures embedded into the surface of the NaAlH(4) crystal exhibit an unambiguous kinetic stability and their general geometric features remain largely unchanged. PMID:20379493

  8. Gas Source Melecular Beam Epitaxy Growth of High Quality AlGaAs Using Trimethylamine Alane as the Aluminum Source

    NASA Astrophysics Data System (ADS)

    Okamoto, Naoya; Ando, Hideyasu; Sandhu, Adarsh; Fujii, Toshio

    1991-12-01

    We investigated the dependence of the background impurity incorporation on growth conditions and optical properties of undoped AlGaAs grown by gas source molecular beam epitaxy using trimethylamine alane (TMAAl), triethylgallium, and arsine. The use of TMAAl enabled us to reduce the carbon concentration (7× 1016 cm-3) to over one order of magnitude less than that using triethylaluminum (TEAl). The 77 K photoluminescence spectrum of undoped AlGaAs grown using TMAAl was dominated by excitonic band-edge emission not observable in AlGaAs grown using TEAl. Furthermore, we report for the first time the doping characteristics of n-type AlGaAs grown using disilane (Si2H6) as an n-type gaseous dopant source together with TMAAl. The carrier concentration (5× 1017--3× 1018 cm-3) in n-AlxGa1-xAs (x{=}0.09--0.27) was reliably controlled and showed the same Si2H6 flow rate dependence as that of GaAs. The activation efficiency of silicon was more than 60%. We demonstrated the excellent n-type doping characteristics by uisng TMAAl.

  9. Decomposition Process of Alane and Gallane Compounds in Metal-Organic Chemical Vapor Deposition Studied by Surface Photo-Absorption

    NASA Astrophysics Data System (ADS)

    Yamauchi, Yoshiharu; Kobayashi, Naoki

    1992-09-01

    We used surface photo-absorption (SPA) to study trimethylamine alane (TMAA) and dimethylamine gallane (DMAG) decomposition processes on a substrate surface in metal-organic chemical vapor deposition. The decomposition onset temperatures of these group III hydride sources correspond to the substrate temperature at which the SPA reflectivity starts to increase during the supply of the group III source onto a group V stabilized surface. It was found that TMAA and DMAG start to decompose at about 150°C on an As-stabilized surface, which is much lower than the decomposition onsets of trialkyl Al and Ga compounds. Low temperature photoluminescence spectra exhibit dominant excitionic emissions for GaAs layers grown by DMAG at substrate temperatures above 400°C, indicating that carbon incorporation and the crystal quality deterioration due to incomplete decomposition on surface is much suppressed by using DMAG. A comparison of AlGaAs photoluminescence between layers by TMAA/triethylgallium and triethylaluminum/triethylgallium shows that the band-to-carbon acceptor transition is greatly reduced by using TMAA. TMAA and DMAG were verified to be promising group III sources for low-temperature and high-purity growth with low-carbon incorporation.

  10. Intermetallic nanoparticles

    SciTech Connect

    Singh, Dileep; Yusufoglu, Yusuf; Timofeeva, Elena; Routbort, Jules L.

    2015-11-20

    A process for preparing intermetallic nanoparticles of two or more metals is provided. In particular, the process includes the steps: a) dispersing nanoparticles of a first metal in a solvent to prepare a first metal solution, b) forming a reaction mixture with the first metal solution and a reducing agent, c) heating the reaction mixture to a reaction temperature; and d) adding a second metal solution containing a salt of a second metal to the reaction mixture. During this process, intermetallic nanoparticles, which contain a compound with the first and second metals are formed. The intermetallic nanoparticles with uniform size and a narrow size distribution is also provided. An electrochemical device such as a battery with the intermetallic nanoparticles is also provided.

  11. Intermetallic nanoparticles

    SciTech Connect

    Singh, Dileep; Yusufoglu, Yusuf; Timofeeva, Elena; Routbort, Jules

    2015-07-14

    A process for preparing intermetallic nanoparticles of two or more metals is provided. In particular, the process includes the steps: a) dispersing nanoparticles of a first metal in a solvent to prepare a first metal solution, b) forming a reaction mixture with the first metal solution and a reducing agent, c) heating the reaction mixture to a reaction temperature; and d) adding a second metal solution containing a salt of a second metal to the reaction mixture. During this process, intermetallic nanoparticles, which contain a compound with the first and second metals are formed. The intermetallic nanoparticles with uniform size and a narrow size distribution is also provided. An electrochemical device such as a battery with the intermetallic nanoparticles is also provided.

  12. Alan F. Guttmacher Lecture.

    PubMed

    Morgentaler, H

    1989-01-01

    In this lecture, Dr. Henry Morgentaler describes how he led the fight to make abortion sage and legal in Canada. In 1967, the Canadian government began exploring possible changes in the abortion law, which at that made abortion a major crime. As president of the Humanist Fellowship of Montreal, Morgentaler presented a brief to House of Commons calling for abortion on request. His appeal attracted great media attention, and soon women started coming to Morgentaler's office seeking abortions. Risking prosecution, Morgentaler agreed to perform the operations (in the process becoming the first doctor in North America to use the vacuum suction technique). His abortion practice grew rapidly. In 1969, the Canadian government made abortion legal if approved by a committee of 3 doctors and if performed in a hospital. Though an improvement over the previous law, the new abortion law still had many deficiencies, most notably: it discriminated against women in rural areas (where the only available hospitals were Catholic), and it made getting an abortion a lengthy process, making the procedure more dangerous. Still campaigning vigorously performing abortions in his Montreal clinic, Morgentaler on charges of illegal abortion by the Quebec government. For the next 6 years, Morgentaler rode a legal roller coaster -- 3 jury acquittals were overturned or disregarded -- serving 10 months in prison throughout the ordeal (the legal battle produced the so-called Morgentaler Amendment, which stipulates that court cannot substitute its own verdict for a jury verdict of not guilty). In 1976, Quebec ended its battle with Morgentaler, who in turn launched his campaign to the rest of Canada. And in 1988, the Canadian Supreme Court rescinded the abortion low, thus affirming the dignity and equality of women. PMID:12284999

  13. Historical streamflows of Double Mountain Fork of Brazos River and water-surface elevations of Lake Alan Henry, Garza County, Texas, water years 1962-2010

    USGS Publications Warehouse

    Asquith, William H.; Vrabel, Joseph

    2011-01-01

    The U.S. Geological Survey (USGS), in cooperation with the City of Lubbock, Texas, operates two surface-water stations in Garza County, Tex.: USGS streamflow-gaging station 08079600 Double Mountain Fork Brazos River at Justiceburg, Tex., and 08079700 Lake Alan Henry Reservoir, a water-supply reservoir about 60 miles southeast of Lubbock, Tex., and about 10 miles east of Justiceburg, Tex. The streamflow and water-surface elevation data from the two stations are useful to water-resource managers and planners in support of forecasting and water-resource infrastructure operations and are used in regional hydrologic studies.

  14. Polymeric nanoparticles

    PubMed Central

    Bolhassani, Azam; Javanzad, Shabnam; Saleh, Tayebeh; Hashemi, Mehrdad; Aghasadeghi, Mohammad Reza; Sadat, Seyed Mehdi

    2014-01-01

    Nanocarriers with various compositions and biological properties have been extensively applied for in vitro/in vivo drug and gene delivery. The family of nanocarriers includes polymeric nanoparticles, lipid-based carriers (liposomes/micelles), dendrimers, carbon nanotubes, and gold nanoparticles (nanoshells/nanocages). Among different delivery systems, polymeric carriers have several properties such as: easy to synthesize, inexpensive, biocompatible, biodegradable, non-immunogenic, non-toxic, and water soluble. In addition, cationic polymers seem to produce more stable complexes led to a more protection during cellular trafficking than cationic lipids. Nanoparticles often show significant adjuvant effects in vaccine delivery since they may be easily taken up by antigen presenting cells (APCs). Natural polymers such as polysaccharides and synthetic polymers have demonstrated great potential to form vaccine nanoparticles. The development of new adjuvants or delivery systems for DNA and protein immunization is an expanding research field. This review describes polymeric carriers especially PLGA, chitosan, and PEI as vaccine delivery systems. PMID:24128651

  15. Precision Nanoparticles

    ScienceCinema

    John Hemminger

    2010-01-08

    A revolutionary technology that efficiently produces nanoparticles in uniform and prescribed sizes (1-100 nanometers) using supercritical fluids. INL researcher Robert Fox was joined by Idaho State University researchers Rene Rodriquez and Joshua Pak in d

  16. Precision Nanoparticles

    SciTech Connect

    John Hemminger

    2009-07-21

    A revolutionary technology that efficiently produces nanoparticles in uniform and prescribed sizes (1-100 nanometers) using supercritical fluids. INL researcher Robert Fox was joined by Idaho State University researchers Rene Rodriquez and Joshua Pak in d

  17. Studies of gas phase reactions, nucleation and growth mechanisms of plasma promoted chemical vapor deposition of aluminum using dimethylethylamine alane as source percursor

    NASA Astrophysics Data System (ADS)

    Knorr, Andreas H.

    The work presented herein focuses on the use of plasma promoted chemical vapor deposition (PPCVD) of aluminum (Al) using dimethylethylamine alane (DMEAA) as source precursor to provide an integrated, low temperature alternative to currently employed Al deposition methods in ultra large sale integration ULSI multilevel metal wiring schemes. In this respect, key findings are reported and discussed from critical scientific and technical aspects of an research and development effort, which was successfully executed to identify a viable Al CVD deposition process. In this respect, advanced atomic scale analytical techniques were successfully employed to characterize the PPCVD deposition process at the molecular level, and document the dependence of film's structural and compositional properties on key process parameters. This led to the development and optimization of a PPCVD Al process for ULSI applications. In addition, gas phase quadrupole mass spectrometry (QMS) was employed to study the gas phase evolution during TCVD and PPCVD in order to gain a thorough understanding of the potential chemical and physical reactions that could occur in the gas phase and derive corresponding optimized reaction pathways for both CVD processes. Key reaction mechanisms involved in thermal and plasma promoted CVD as a function of processing parameters were investigated, including the role of hydrogen plasma in providing an efficient pathway to aluminum nucleation and growth. The resulting reaction mechanisms were then employed to identify the most likely precursor decomposition pathways and explore relevant implications for thermal and plasma promoted CVD Al. Furthermore, the nucleation and growth of Al in both TCVD and PPCVD were thoroughly characterized. Time evolution studies were carried out employing a variety of relevant liners and seed layers under selected surface chemical states. The surface morphology of the resulting films were analyzed by means of scanning probe microscopy

  18. Advances in the electrochemical regeneration of aluminum hydride

    NASA Astrophysics Data System (ADS)

    Martínez-Rodríguez, Michael J.; García-Díaz, Brenda L.; Teprovich, Joseph A.; Knight, Douglas A.; Zidan, Ragaiy

    2012-03-01

    In previous work, a reversible cycle that uses electrolysis and catalytic hydrogenation of spent Al(s) for the regeneration of alane (AlH3) was reported. In this study, the electrochemical synthesis of alane is improved. Advances in the electrochemical regeneration of alane have been achieved via the use of lithium aluminum hydride (LiAlH4) and lithium chloride (LiCl). Lithium chloride reacts in a cyclic process and functions as an electro-catalytic additive that enhances the electrochemical process by increasing the cell efficiency and the alane production. Electrochemical techniques are used to show that the increased rate of alane generation is due to the electro-catalytic effect of lithium chloride, rather than an electrolyte enhanced effect.

  19. Assessing Nanoparticle Toxicity

    NASA Astrophysics Data System (ADS)

    Love, Sara A.; Maurer-Jones, Melissa A.; Thompson, John W.; Lin, Yu-Shen; Haynes, Christy L.

    2012-07-01

    Nanoparticle toxicology, an emergent field, works toward establishing the hazard of nanoparticles, and therefore their potential risk, in light of the increased use and likelihood of exposure. Analytical chemists can provide an essential tool kit for the advancement of this field by exploiting expertise in sample complexity and preparation as well as method and technology development. Herein, we discuss experimental considerations for performing in vitro nanoparticle toxicity studies, with a focus on nanoparticle characterization, relevant model cell systems, and toxicity assay choices. Additionally, we present three case studies (of silver, titanium dioxide, and carbon nanotube toxicity) to highlight the important toxicological considerations of these commonly used nanoparticles.

  20. De-alloyed platinum nanoparticles

    DOEpatents

    Strasser, Peter; Koh, Shirlaine; Mani, Prasanna; Ratndeep, Srivastava

    2011-08-09

    A method of producing de-alloyed nanoparticles. In an embodiment, the method comprises admixing metal precursors, freeze-drying, annealing, and de-alloying the nanoparticles in situ. Further, in an embodiment de-alloyed nanoparticle formed by the method, wherein the nanoparticle further comprises a core-shell arrangement. The nanoparticle is suitable for electrocatalytic processes and devices.

  1. The Alan Gregg Memorial Lecture

    ERIC Educational Resources Information Center

    Brewster, Kingman, Jr.

    1970-01-01

    All university professionals must make greater effort to mobilize local, state and national public opinion to support the creation and funding of non-academic public service institutions to meet social needs of the community. Delivered at the 80th Annual Meeting of AAMC, Nov. 1, 1969. (IR)

  2. The ALAN Review. Winter 1986.

    ERIC Educational Resources Information Center

    Reed, Arthea, Ed.

    1986-01-01

    Intended for junior or senior high school English teachers, articles and features in this journal issue focus on young adult literature and the adolescent audience. The first article, Kevin Major's "The Truth about My Fictitious Friends," describes the genesis of the author's fiction writing for the Newfoundland audience, and is followed by a…

  3. The ALAN Review. Fall 1984.

    ERIC Educational Resources Information Center

    Reed, Arthea, Ed.

    1984-01-01

    Intended for junior high and high school English teachers, the articles and features in this journal focus on adolescent literature and the young adult audience. Articles in the journal discuss (1) politics as an emerging topic in young adult novels, (2) teacher attitudes and practices relevant to the use of the young adult novel in secondary…

  4. The ALAN Review. Winter, 1984.

    ERIC Educational Resources Information Center

    Ellis, W. Geiger, Ed.

    1984-01-01

    Intended for the junior high school or secondary school English teacher, the articles and features in this journal focus on young adult literatue and the adolescent audience. The first article, Zibby Oneal's "Writing for Adolescents: Pleasures and Problems," describes the responsibilities of authors of adolescent fiction, while the second article,…

  5. Nanoparticles and direct immunosuppression.

    PubMed

    Ngobili, Terrika A; Daniele, Michael A

    2016-05-01

    Targeting the immune system with nanomaterials is an intensely active area of research. Specifically, the capability to induce immunosuppression is a promising complement for drug delivery and regenerative medicine therapies. Many novel strategies for immunosuppression rely on nanoparticles as delivery vehicles for small-molecule immunosuppressive compounds. As a consequence, efforts in understanding the mechanisms in which nanoparticles directly interact with the immune system have been overshadowed. The immunological activity of nanoparticles is dependent on the physiochemical properties of the nanoparticles and its subsequent cellular internalization. As the underlying factors for these reactions are elucidated, more nanoparticles may be engineered and evaluated for inducing immunosuppression and complementing immunosuppressive drugs. This review will briefly summarize the state-of-the-art and developments in understanding how nanoparticles induce immunosuppressive responses, compare the inherent properties of nanomaterials which induce these immunological reactions, and comment on the potential for using nanomaterials to modulate and control the immune system. PMID:27229901

  6. Stimulus Responsive Nanoparticles

    NASA Technical Reports Server (NTRS)

    Cairns, Darran Robert (Inventor); Huebsch, Wade W. (Inventor); Sierros, Konstantinos A. (Inventor); Shafran, Matthew S. (Inventor)

    2015-01-01

    Disclosed are various embodiments of methods and systems related to stimulus responsive nanoparticles. In one embodiment includes a stimulus responsive nanoparticle system, the system includes a first electrode, a second electrode, and a plurality of elongated electro-responsive nanoparticles dispersed between the first and second electrodes, the plurality of electro-responsive nanorods configured to respond to an electric field established between the first and second electrodes.

  7. Stimulus responsive nanoparticles

    NASA Technical Reports Server (NTRS)

    Cairns, Darren Robert (Inventor); Huebsch, Wade W. (Inventor); Sierros, Konstantinos A. (Inventor); Shafran, Matthew S. (Inventor)

    2013-01-01

    Disclosed are various embodiments of methods and systems related to stimulus responsive nanoparticles. In one embodiment includes a stimulus responsive nanoparticle system, the system includes a first electrode, a second electrode, and a plurality of elongated electro-responsive nanoparticles dispersed between the first and second electrodes, the plurality of electro-responsive nanorods configured to respond to an electric field established between the first and second electrodes.

  8. Nanoparticles for biomedical imaging

    PubMed Central

    Nune, Satish K; Gunda, Padmaja; Thallapally, Praveen K; Lin, Ying-Ying; Forrest, M Laird; Berkland, Cory J

    2011-01-01

    Background Synthetic nanoparticles are emerging as versatile tools in biomedical applications, particularly in the area of biomedical imaging. Nanoparticles 1 – 100 nm in diameter have dimensions comparable to biological functional units. Diverse surface chemistries, unique magnetic properties, tunable absorption and emission properties, and recent advances in the synthesis and engineering of various nanoparticles suggest their potential as probes for early detection of diseases such as cancer. Surface functionalization has expanded further the potential of nanoparticles as probes for molecular imaging. Objective To summarize emerging research of nanoparticles for biomedical imaging with increased selectivity and reduced nonspecific uptake with increased spatial resolution containing stabilizers conjugated with targeting ligands. Methods This review summarizes recent technological advances in the synthesis of various nanoparticle probes, and surveys methods to improve the targeting of nanoparticles for their application in biomedical imaging. Conclusion Structural design of nanomaterials for biomedical imaging continues to expand and diversify. Synthetic methods have aimed to control the size and surface characteristics of nanoparticles to control distribution, half-life and elimination. Although molecular imaging applications using nanoparticles are advancing into clinical applications, challenges such as storage stability and long-term toxicology should continue to be addressed. PMID:19743894

  9. Biocompatible nanoparticles and biopolyelectrolytes

    NASA Astrophysics Data System (ADS)

    Zribi, Olena

    The research presented in this manuscript encompasses a merger of two research directions: a study of aqueous nanoparticle colloids and a study of biological polyelectrolytes. The majority of biomedical applications of nanoparticles require stable aqueous colloids of nanoparticles as a starting point. A new one-step method of preparation of aqueous solutions of ultra-fine ferroelectric barium titanate nanoparticles was developed and generalized to the preparation of stable aqueous colloids of semiconductor nanoparticles. This high-energy ball milling technique is low cost, environmentally friendly, and allows for control of nanoparticle size by changing milling time. Aqueous colloids of BaTiO3 nanoparticles are stable over time, maintain ferroelectricity and can be used as second harmonic generating nanoprobes for biomedical imaging. Biopolyelectrolytes exhibit a variety of novel liquid-crystalline phases in aqueous solutions where their electrolytic nature is a driving force behind phase formation. We study medically relevant mixtures of F-actin, DNA and oppositely charged ions (such as multivalent salts and antibiotic drugs) and map out phase diagrams and laws that govern phase transitions. We combine these research directions in studies of the condensation behavior in aqueous solutions of biocompatible nanoparticles and biopolyelectrolytes.

  10. Nanoparticle Oscillations and Fronts

    SciTech Connect

    Lagzi, Istvan; Kowalczyk, Bartlomiej; Wang, Dawei; Grzybowski, Bartosz A.

    2010-09-30

    Chemical oscillations can be coupled to the dynamic self-assembly of nanoparticles. Periodic pH changes translate into protonation and deprotonation of the ligands that stabilize the nanoparticles, thus altering repulsive and attractive interparticle forces. In a continuous stirred-tank reactor, rhythmic aggregation and dispersion is observed; in spatially distributed media, propagation of particle aggregation fronts is seen.

  11. Single nanoparticle plasmonic sensors.

    PubMed

    Sriram, Manish; Zong, Kelly; Vivekchand, S R C; Gooding, J Justin

    2015-01-01

    The adoption of plasmonic nanomaterials in optical sensors, coupled with the advances in detection techniques, has opened the way for biosensing with single plasmonic particles. Single nanoparticle sensors offer the potential to analyse biochemical interactions at a single-molecule level, thereby allowing us to capture even more information than ensemble measurements. We introduce the concepts behind single nanoparticle sensing and how the localised surface plasmon resonances of these nanoparticles are dependent upon their materials, shape and size. Then we outline the different synthetic approaches, like citrate reduction, seed-mediated and seedless growth, that enable the synthesis of gold and silver nanospheres, nanorods, nanostars, nanoprisms and other nanostructures with tunable sizes. Further, we go into the aspects related to purification and functionalisation of nanoparticles, prior to the fabrication of sensing surfaces. Finally, the recent developments in single nanoparticle detection, spectroscopy and sensing applications are discussed. PMID:26473866

  12. Single Nanoparticle Plasmonic Sensors

    PubMed Central

    Sriram, Manish; Zong, Kelly; Vivekchand, S. R. C.; Gooding, J. Justin

    2015-01-01

    The adoption of plasmonic nanomaterials in optical sensors, coupled with the advances in detection techniques, has opened the way for biosensing with single plasmonic particles. Single nanoparticle sensors offer the potential to analyse biochemical interactions at a single-molecule level, thereby allowing us to capture even more information than ensemble measurements. We introduce the concepts behind single nanoparticle sensing and how the localised surface plasmon resonances of these nanoparticles are dependent upon their materials, shape and size. Then we outline the different synthetic approaches, like citrate reduction, seed-mediated and seedless growth, that enable the synthesis of gold and silver nanospheres, nanorods, nanostars, nanoprisms and other nanostructures with tunable sizes. Further, we go into the aspects related to purification and functionalisation of nanoparticles, prior to the fabrication of sensing surfaces. Finally, the recent developments in single nanoparticle detection, spectroscopy and sensing applications are discussed. PMID:26473866

  13. Nanoparticle Approaches against Bacterial Infections

    PubMed Central

    Gao, Weiwei; Thamphiwatana, Soracha; Angsantikul, Pavimol; Zhang, Liangfang

    2014-01-01

    Despite the wide success of antibiotics, the treatment of bacterial infection still faces significant challenges, particularly the emergence of antibiotic resistance. As a result, nanoparticle drug delivery platforms including liposomes, polymeric nanoparticles, dendrimers, and various inorganic nanoparticles have been increasingly exploited to enhance the therapeutic effectiveness of existing antibiotics. This review focuses on areas where nanoparticle approaches hold significant potential to advance the treatment of bacterial infection. These areas include targeted antibiotic delivery, environmentally responsive antibiotic delivery, combinatorial antibiotic delivery, nanoparticle-enabled antibacterial vaccination, and nanoparticle-based bacterial detection. In each area we highlight the innovative antimicrobial nanoparticle platforms and review their progress made against bacterial infections. PMID:25044325

  14. Electronically cloaked nanoparticles

    NASA Astrophysics Data System (ADS)

    Shen, Wenqing

    The concept of electronic cloaking is to design objects invisible to conduction electrons. The approach of electronic cloaking has been recently suggested to design invisible nanoparticle dopants with electronic scattering cross section smaller than 1% of the physical cross section (pi a2), and therefore to enhance the carrier mobility of bulk materials. The proposed nanoparticles have core-shell structures. The dopants are incorporated inside the core, while the shell layer serves both as a spacer to separate the charge carriers from their parent atoms and as a cloaking shell to minimize the scattering cross section of the electrons from the ionized nanoparticles. Thermoelectric materials are usually highly doped to have enough carrier density. Using invisible dopants could achieve larger thermoelectric power factors by enhancing the electronic mobility. Core-shell nanoparticles show an advantage over one-layer nanoparticles, which are proposed in three-dimensional modulation doping. However designing such nanoparticles is not easy as there are too many parameters to be considered. This thesis first shows an approach to design hollow nanoparticles by applying constrains on variables. In the second part, a simple mapping approach is introduced where one can identify possible core-shell particles by comparing the dimensionless parameters of chosen materials with provided maps. In both parts of this work, several designs with realistic materials were made and proven to achieve electronic cloaking. Improvement in the thermoelectric power factor compared to the traditional impurity doping method was demonstrated in several cases.

  15. Gas Phase Nanoparticle Synthesis

    NASA Astrophysics Data System (ADS)

    Granqvist, Claes; Kish, Laszlo; Marlow, William

    This book deals with gas-phase nanoparticle synthesis and is intended for researchers and research students in nanomaterials science and engineering, condensed matter physics and chemistry, and aerosol science. Gas-phase nanoparticle synthesis is instrumental to nanotechnology - a field in current focus that raises hopes for environmentally benign, resource-lean manufacturing. Nanoparticles can be produced by many physical, chemical, and even biological routes. Gas-phase synthesis is particularly interesting since one can achieve accurate manufacturing control and hence industrial viability.

  16. Shaped gold and silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Sun, Yugang; An, Changhua

    2011-03-01

    Advance in the synthesis of shaped nanoparticles made of gold and silver is reviewed in this article. This review starts with a new angle by analyzing the relationship between the geometrical symmetry of a nanoparticle shape and its internal crystalline structures. According to the relationship, the nanoparticles with well-defined shapes are classified into three categories: nanoparticles with single crystallinity, nanoparticles with angular twins, and nanoparticles with parallel twins. Discussion and analysis on the classical methods for the synthesis of shaped nanoparticles in each category are also included and personal perspectives on the future research directions in the synthesis of shaped metal nanoparticles are briefly summarized. This review is expected to provide a guideline in designing the strategy for the synthesis of shaped nanoparticles and analyzing the corresponding growth mechanism.

  17. Functionalization of Semiconductor Nanoparticles

    NASA Astrophysics Data System (ADS)

    Baraton, M.-I.

    Functionalization of nanoparticles surface by attachment of organic entities is used to achieve and tailor many new properties, such as lubrication, optical response, chemical sensing, or biocompatibility. But because at the nanometer scale the surface properties significantly contribute to the overall properties, the consequences of the surface modifications have to be thoroughly evaluated. This paper demonstrates the relevance of Fourier transform infrared spectroscopy to the study of the surface reactions leading to the functionalization, and of the stability of the functionalized surface under the expected working conditions. In the case of semiconductor nanoparticles, this technique additionally allows the analysis of the impact of the functionalization on the electrical properties. This will be illustrated by the case study of tin oxide nanoparticles for chemical gas sensors. The correlation between surface chemistry and electrical properties is critical to optimize the nanoparticles functionalization for the targeted properties.

  18. Magnetic nanoparticle temperature estimation

    SciTech Connect

    Weaver, John B.; Rauwerdink, Adam M.; Hansen, Eric W.

    2009-05-15

    The authors present a method of measuring the temperature of magnetic nanoparticles that can be adapted to provide in vivo temperature maps. Many of the minimally invasive therapies that promise to reduce health care costs and improve patient outcomes heat tissue to very specific temperatures to be effective. Measurements are required because physiological cooling, primarily blood flow, makes the temperature difficult to predict a priori. The ratio of the fifth and third harmonics of the magnetization generated by magnetic nanoparticles in a sinusoidal field is used to generate a calibration curve and to subsequently estimate the temperature. The calibration curve is obtained by varying the amplitude of the sinusoidal field. The temperature can then be estimated from any subsequent measurement of the ratio. The accuracy was 0.3 deg. K between 20 and 50 deg. C using the current apparatus and half-second measurements. The method is independent of nanoparticle concentration and nanoparticle size distribution.

  19. Renal Clearance of Nanoparticles

    PubMed Central

    Choi, Hak Soo; Liu, Wenhao; Misra, Preeti; Tanaka, Eiichi; Zimmer, John P.; Ipe, Binil Itty; Bawendi, Moungi G.; Frangioni, John V.

    2008-01-01

    SUMMARY The field of nanotechnology holds great promise for the diagnosis and treatment of human disease. However, the size and charge of most nanoparticles preclude their efficient clearance from the body as intact nanoparticles. Without such clearance or their biodegradation into biologically benign components, toxicity is potentially amplified and radiological imaging is hindered. Using quantum dots (QDs) as a model system, we have precisely defined the requirements for renal filtration and urinary excretion of inorganic, metal-containing nanoparticles. Zwitterionic or neutral organic coatings prevented adsorption of serum proteins, which otherwise increased hydrodynamic diameter (HD) by over 15 nm and prevented renal excretion. A final HD smaller than 5.5 nm resulted in rapid and efficient urinary excretion, and elimination of QDs from the body. This study provides a foundation for the design and development of biologically targeted nanoparticles for biomedical applications. PMID:17891134

  20. Theoretical Approaches to Nanoparticles

    NASA Astrophysics Data System (ADS)

    Kempa, Krzysztof

    Nanoparticles can be viewed as wave resonators. Involved waves are, for example, carrier waves, plasmon waves, polariton waves, etc. A few examples of successful theoretical treatments that follow this approach are given. In one, an effective medium theory of a nanoparticle composite is presented. In another, plasmon polaritonic solutions allow to extend concepts of radio technology, such as an antenna and a coaxial transmission line, to the visible frequency range.

  1. DNA-Nanoparticle Tinkertoys.

    PubMed

    Chandrasekaran, Arun Richard

    2016-06-16

    Nanoparticle superlattices can be self-assembled by using DNA linkers, which gives control over their size, shape, and composition. Recently, such programmable atom equivalents have been tailored to respond to chemical stimuli and result in specific crystalline lattices. Moreover, the molecular recognition properties and the robustness of designed DNA nanostructures have been used in combination with metallic nanoparticles for the production of the elusive diamond superlattice. PMID:27080095

  2. Imaging through plasmonic nanoparticles

    NASA Astrophysics Data System (ADS)

    Tanzid, Mehbuba; Sobhani, Ali; DeSantis, Christopher J.; Cui, Yao; Hogan, Nathaniel J.; Samaniego, Adam; Veeraraghavan, Ashok; Halas, Naomi J.

    2016-05-01

    The optical properties of metallic nanoparticles with plasmon resonances have been studied extensively, typically by measuring the transmission of light, as a function of wavelength, through a nanoparticle suspension. One question that has not yet been addressed, however, is how an image is transmitted through such a suspension of absorber-scatterers, in other words, how the various spatial frequencies are attenuated as they pass through the nanoparticle host medium. Here, we examine how the optical properties of a suspension of plasmonic nanoparticles affect the transmitted image. We use two distinct ways to assess transmitted image quality: the structural similarity index (SSIM), a perceptual distortion metric based on the human visual system, and the modulation transfer function (MTF), which assesses the resolvable spatial frequencies. We show that perceived image quality, as well as spatial resolution, are both dependent on the scattering and absorption cross-sections of the constituent nanoparticles. Surprisingly, we observe a nonlinear dependence of image quality on optical density by varying optical path length and nanoparticle concentration. This work is a first step toward understanding the requirements for visualizing and resolving objects through media consisting of subwavelength absorber-scatterer structures, an approach that should also prove useful in the assessment of metamaterial or metasurface-based optical imaging systems.

  3. Externally modulated theranostic nanoparticles

    PubMed Central

    Urban, Cordula; Urban, Alexander S.; Charron, Heather; Joshi, Amit

    2013-01-01

    Externally modulated nanoparticles comprise a rapidly advancing class of cancer nanotherapeutics, which combine the favorable tumor accumulation of nanoparticles, with external spatio-temporal control on therapy delivery via optical, magnetic, or ultrasound modalities. The local control on therapy enables higher tumor treatment efficacy, while simultaneously reducing off-target effects. The nanoparticle interactions with external fields have an additional advantage of frequently generating an imaging signal, and thus such agents provide theranostic (both diagnostic and therapeutic) capabilities. In this review, we classify the emerging externally modulated theranostic nanoparticles according to the mode of external control and describe the physiochemical mechanisms underlying the external control of therapy, and illustrate the major embodiments of nanoparticles in each class with proven biological efficacy: (I) electromagnetic radiation in visible and near-infrared range is being exploited for gold based and carbon nanostructures with tunable surface plasmon resonance (SPR) for imaging and photothermal therapy (PTT) of cancer, photochemistry based manipulations are employed for light sensitive liposomes and porphyrin based nanoparticles; (II) Magnetic field based manipulations are being developed for iron-oxide based nanostructures for magnetic resonance imaging (MRI) and magnetothermal therapy; (III) ultrasound based methods are primarily being employed to increase delivery of conventional drugs and nanotherapeutics to tumor sites. PMID:24834381

  4. Imaging through plasmonic nanoparticles

    PubMed Central

    Tanzid, Mehbuba; Sobhani, Ali; DeSantis, Christopher J.; Cui, Yao; Hogan, Nathaniel J.; Samaniego, Adam; Veeraraghavan, Ashok; Halas, Naomi J.

    2016-01-01

    The optical properties of metallic nanoparticles with plasmon resonances have been studied extensively, typically by measuring the transmission of light, as a function of wavelength, through a nanoparticle suspension. One question that has not yet been addressed, however, is how an image is transmitted through such a suspension of absorber-scatterers, in other words, how the various spatial frequencies are attenuated as they pass through the nanoparticle host medium. Here, we examine how the optical properties of a suspension of plasmonic nanoparticles affect the transmitted image. We use two distinct ways to assess transmitted image quality: the structural similarity index (SSIM), a perceptual distortion metric based on the human visual system, and the modulation transfer function (MTF), which assesses the resolvable spatial frequencies. We show that perceived image quality, as well as spatial resolution, are both dependent on the scattering and absorption cross-sections of the constituent nanoparticles. Surprisingly, we observe a nonlinear dependence of image quality on optical density by varying optical path length and nanoparticle concentration. This work is a first step toward understanding the requirements for visualizing and resolving objects through media consisting of subwavelength absorber-scatterer structures, an approach that should also prove useful in the assessment of metamaterial or metasurface-based optical imaging systems. PMID:27140618

  5. Imaging through plasmonic nanoparticles.

    PubMed

    Tanzid, Mehbuba; Sobhani, Ali; DeSantis, Christopher J; Cui, Yao; Hogan, Nathaniel J; Samaniego, Adam; Veeraraghavan, Ashok; Halas, Naomi J

    2016-05-17

    The optical properties of metallic nanoparticles with plasmon resonances have been studied extensively, typically by measuring the transmission of light, as a function of wavelength, through a nanoparticle suspension. One question that has not yet been addressed, however, is how an image is transmitted through such a suspension of absorber-scatterers, in other words, how the various spatial frequencies are attenuated as they pass through the nanoparticle host medium. Here, we examine how the optical properties of a suspension of plasmonic nanoparticles affect the transmitted image. We use two distinct ways to assess transmitted image quality: the structural similarity index (SSIM), a perceptual distortion metric based on the human visual system, and the modulation transfer function (MTF), which assesses the resolvable spatial frequencies. We show that perceived image quality, as well as spatial resolution, are both dependent on the scattering and absorption cross-sections of the constituent nanoparticles. Surprisingly, we observe a nonlinear dependence of image quality on optical density by varying optical path length and nanoparticle concentration. This work is a first step toward understanding the requirements for visualizing and resolving objects through media consisting of subwavelength absorber-scatterer structures, an approach that should also prove useful in the assessment of metamaterial or metasurface-based optical imaging systems. PMID:27140618

  6. Introduction to metallic nanoparticles.

    PubMed

    Mody, Vicky V; Siwale, Rodney; Singh, Ajay; Mody, Hardik R

    2010-10-01

    Metallic nanoparticles have fascinated scientist for over a century and are now heavily utilized in biomedical sciences and engineering. They are a focus of interest because of their huge potential in nanotechnology. Today these materials can be synthesized and modified with various chemical functional groups which allow them to be conjugated with antibodies, ligands, and drugs of interest and thus opening a wide range of potential applications in biotechnology, magnetic separation, and preconcentration of target analytes, targeted drug delivery, and vehicles for gene and drug delivery and more importantly diagnostic imaging. Moreover, various imaging modalities have been developed over the period of time such as MRI, CT, PET, ultrasound, SERS, and optical imaging as an aid to image various disease states. These imaging modalities differ in both techniques and instrumentation and more importantly require a contrast agent with unique physiochemical properties. This led to the invention of various nanoparticulated contrast agent such as magnetic nanoparticles (Fe(3)O(4)), gold, and silver nanoparticles for their application in these imaging modalities. In addition, to use various imaging techniques in tandem newer multifunctional nanoshells and nanocages have been developed. Thus in this review article, we aim to provide an introduction to magnetic nanoparticles (Fe(3)O(4)), gold nanoparticles, nanoshells and nanocages, and silver nanoparticles followed by their synthesis, physiochemical properties, and citing some recent applications in the diagnostic imaging and therapy of cancer. PMID:21180459

  7. Introduction to metallic nanoparticles

    PubMed Central

    Mody, Vicky V.; Siwale, Rodney; Singh, Ajay; Mody, Hardik R.

    2010-01-01

    Metallic nanoparticles have fascinated scientist for over a century and are now heavily utilized in biomedical sciences and engineering. They are a focus of interest because of their huge potential in nanotechnology. Today these materials can be synthesized and modified with various chemical functional groups which allow them to be conjugated with antibodies, ligands, and drugs of interest and thus opening a wide range of potential applications in biotechnology, magnetic separation, and preconcentration of target analytes, targeted drug delivery, and vehicles for gene and drug delivery and more importantly diagnostic imaging. Moreover, various imaging modalities have been developed over the period of time such as MRI, CT, PET, ultrasound, SERS, and optical imaging as an aid to image various disease states. These imaging modalities differ in both techniques and instrumentation and more importantly require a contrast agent with unique physiochemical properties. This led to the invention of various nanoparticulated contrast agent such as magnetic nanoparticles (Fe3O4), gold, and silver nanoparticles for their application in these imaging modalities. In addition, to use various imaging techniques in tandem newer multifunctional nanoshells and nanocages have been developed. Thus in this review article, we aim to provide an introduction to magnetic nanoparticles (Fe3O4), gold nanoparticles, nanoshells and nanocages, and silver nanoparticles followed by their synthesis, physiochemical properties, and citing some recent applications in the diagnostic imaging and therapy of cancer. PMID:21180459

  8. Heteroaggregation of cerium oxide nanoparticles and nanoparticles of pyrolyzed biomass

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Heteroaggregation with indigenous particles is an important process controlling the mobility of engineered nanomaterials in the environment. We studied heteroaggregation of cerium oxide nanoparticles (n-CeO2), which are widely used commercially, with nanoparticles of pyrogenic carbonaceous material ...

  9. Direct hierarchical assembly of nanoparticles

    DOEpatents

    Xu, Ting; Zhao, Yue; Thorkelsson, Kari

    2014-07-22

    The present invention provides hierarchical assemblies of a block copolymer, a bifunctional linking compound and a nanoparticle. The block copolymers form one micro-domain and the nanoparticles another micro-domain.

  10. MEASUREMENT OF NANOPARTICLES IN WATER

    EPA Science Inventory

    Measuring nanoparticles in water differs from traditional dissolved solute measurement in several ways. The most salient difference is that nanoparticles are colloids rather than solutes and therefore are subject to the interparticle interactions (mainly electrostatic and Van de...

  11. Gold Nanoparticles Cytotoxicity

    NASA Astrophysics Data System (ADS)

    Mironava, Tatsiana

    Over the last two decades gold nanoparticles (AuNPs) have been used for many scientific applications and have attracted attention due to the specific chemical, electronic and optical size dependent properties that make them very promising agents in many fields such as medicine, imagine techniques and electronics. More specifically, biocompatible gold nanoparticles have a huge potential for use as the contrast augmentation agent in X-ray Computed Tomography and Photo Acoustic Tomography for early tumor diagnostic as well these nanoparticles are extensively researched for enhancing the targeted cancer treatment effectiveness such as photo-thermal and radiotherapy. In most biomedical applications biocompatible gold nanoparticles are labeled with specific tumor or other pathology targeting antibodies and used for site specific drug delivery. However, even though gold nanoparticles poses very high level of anti cancer properties, the question of their cytotoxicity ones they are released in normal tissue has to be researched. Moreover, the huge amount of industrially produced gold nanoparticles raises the question of these particles being a health hazard, since the penetration is fairly easy for the "nano" size substances. This study focuses on the effect of AuNPs on a human skin tissue, since it is fall in both categories -- the side effects for biomedical applications and industrial workers and users' exposure during production and handling. Therefore, in the present project, gold nanoparticles stabilized with the biocompatible agent citric acid were generated and characterized by Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). The cytotoxic effect of AuNPs release to healthy skin tissue was modeled on 3 different cell types: human keratinocytes, human dermal fibroblasts, and human adipose derived stromal (ADS) cells. The AuNPs localization inside the cell was found to be cell type dependent. Overall cytotoxicity was found to be dependent

  12. Lactobacillusassisted synthesis of titanium nanoparticles

    PubMed Central

    2007-01-01

    An eco-friendlylactobacillussp. (microbe) assisted synthesis of titanium nanoparticles is reported. The synthesis is performed at room temperature. X-ray and transmission electron microscopy analyses are performed to ascertain the formation of Ti nanoparticles. Individual nanoparticles as well as a number of aggregates almost spherical in shape having a size of 40–60 nm are found.

  13. Virus templated metallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Aljabali, Alaa A. A.; Barclay, J. Elaine; Lomonossoff, George P.; Evans, David J.

    2010-12-01

    Plant viruses are considered as nanobuilding blocks that can be used as synthons or templates for novel materials. Cowpea mosaic virus (CPMV) particles have been shown to template the fabrication of metallic nanoparticles by an electroless deposition metallization process. Palladium ions were electrostatically bound to the virus capsid and, when reduced, acted as nucleation sites for the subsequent metal deposition from solution. The method, although simple, produced highly monodisperse metallic nanoparticles with a diameter of ca. <=35 nm. CPMV-templated particles were prepared with cobalt, nickel, iron, platinum, cobalt-platinum and nickel-iron.Plant viruses are considered as nanobuilding blocks that can be used as synthons or templates for novel materials. Cowpea mosaic virus (CPMV) particles have been shown to template the fabrication of metallic nanoparticles by an electroless deposition metallization process. Palladium ions were electrostatically bound to the virus capsid and, when reduced, acted as nucleation sites for the subsequent metal deposition from solution. The method, although simple, produced highly monodisperse metallic nanoparticles with a diameter of ca. <=35 nm. CPMV-templated particles were prepared with cobalt, nickel, iron, platinum, cobalt-platinum and nickel-iron. Electronic supplementary information (ESI) available: Additional experimental detail, agarose gel electrophoresis results, energy dispersive X-ray spectra, ζ-potential measurements, dynamic light scattering data, nanoparticle tracking analysis and an atomic force microscopy image of Ni-CPMV. See DOI: 10.1039/c0nr00525h

  14. Virus templated metallic nanoparticles.

    PubMed

    Aljabali, Alaa A A; Barclay, J Elaine; Lomonossoff, George P; Evans, David J

    2010-12-01

    Plant viruses are considered as nanobuilding blocks that can be used as synthons or templates for novel materials. Cowpea mosaic virus (CPMV) particles have been shown to template the fabrication of metallic nanoparticles by an electroless deposition metallization process. Palladium ions were electrostatically bound to the virus capsid and, when reduced, acted as nucleation sites for the subsequent metal deposition from solution. The method, although simple, produced highly monodisperse metallic nanoparticles with a diameter of ca. ≤35 nm. CPMV-templated particles were prepared with cobalt, nickel, iron, platinum, cobalt-platinum and nickel-iron. PMID:20877898

  15. Nanoparticles from renewable polymers

    PubMed Central

    Wurm, Frederik R.; Weiss, Clemens K.

    2014-01-01

    The use of polymers from natural resources can bring many benefits for novel polymeric nanoparticle systems. Such polymers have a variety of beneficial properties such as biodegradability and biocompatibility, they are readily available on large scale and at low cost. As the amount of fossil fuels decrease, their application becomes more interesting even if characterization is in many cases more challenging due to structural complexity, either by broad distribution of their molecular weights (polysaccharides, polyesters, lignin) or by complex structure (proteins, lignin). This review summarizes different sources and methods for the preparation of biopolymer-based nanoparticle systems for various applications. PMID:25101259

  16. TOPICAL REVIEW: Biopolymeric nanoparticles

    NASA Astrophysics Data System (ADS)

    Sundar, Sushmitha; Kundu, Joydip; Kundu, Subhas C.

    2010-02-01

    This review on nanoparticles highlights the various biopolymers (proteins and polysaccharides) which have recently revolutionized the world of biocompatible and degradable natural biological materials. The methods of their fabrication, including emulsification, desolvation, coacervation and electrospray drying are described. The characterization of different parameters for a given nanoparticle, such as particle size, surface charge, morphology, stability, structure, cellular uptake, cytotoxicity, drug loading and drug release, is outlined together with the relevant measurement techniques. Applications in the fields of medicine and biotechnology are discussed along with a promising future scope.

  17. PEGylated Inorganic Nanoparticles

    SciTech Connect

    Karakoti, Ajay S.; Das, Soumya; Thevuthasan, Suntharampillai; Seal, Sudipta

    2011-02-25

    Application of inorganic nanoparticles in diagnosis and therapy has become a critical component in targeted treatment of diseases. The surface modification of inorganic oxides is important for providing diversity in size, shape, solubility, long term stability and attachment of selective functional groups. PEGylation of surfaces is a key strategic approach for providing stealth characteristics to nanomaterials otherwise identified as foreign materials by human body. The current review describes the role of surface modification of oxides by polyethylene glycol (PEG) in providing versatile characteristics to inorganic oxide nanoparticles with a focus on their biomedical applications. The role of PEG as structure directing agent in synthesis of oxides is also captured in this short review.

  18. Nanoparticle shuttle memory

    DOEpatents

    Zettl, Alex Karlwalter

    2012-03-06

    A device for storing data using nanoparticle shuttle memory having a nanotube. The nanotube has a first end and a second end. A first electrode is electrically connected to the first end of the nanotube. A second electrode is electrically connected to the second end of the nanotube. The nanotube has an enclosed nanoparticle shuttle. A switched voltage source is electrically connected to the first electrode and the second electrode, whereby a voltage may be controllably applied across the nanotube. A resistance meter is also connected to the first electrode and the second electrode, whereby the electrical resistance across the nanotube can be determined.

  19. Chemical Aspects of Nanoparticle Ecotoxicology.

    PubMed

    Sigg, Laura; Behra, Renata; Groh, Ksenia; Isaacson, Carl; Odzak, Niksa; Piccapietra, Flavio; Röhder, Lena; Schug, Hannah; Yue, Yang; Schirmer, Kristin

    2014-11-01

    Nanoecotoxicology strives to understand the processes and mechanisms by which engineered nanoparticles (ENP) may exert toxic effects on aquatic organisms. Detailed knowledge of the chemical reactions of nanoparticles in the media and of their interactions with organisms is required to understand these effects. The processes of agglomeration of nanoparticles, of dissolution and release of toxic metal ions, and of production of reactive oxygen species (ROS) are considered in this article. Important questions concern the role of uptake of nanoparticles in various organisms, in contrast to uptake of ions released from nanoparticles and to nanoparticle attachment to organism surfaces. These interactions are illustrated for effects of silver nanoparticles (AgNP), cerium oxide (CeO2 NP) and titanium dioxide (TiO2 NP), on aquatic organisms, including algae, biofilms, fish cells and fish embryos. PMID:26508489

  20. Nanoparticles: pharmacological and toxicological significance

    PubMed Central

    Medina, C; Santos-Martinez, M J; Radomski, A; Corrigan, O I; Radomski, M W

    2007-01-01

    Nanoparticles are tiny materials (<1000 nm in size) that have specific physicochemical properties different to bulk materials of the same composition and such properties make them very attractive for commercial and medical development. However, nanoparticles can act on living cells at the nanolevel resulting not only in biologically desirable, but also in undesirable effects. In contrast to many efforts aimed at exploiting desirable properties of nanoparticles for medicine, there are limited attempts to evaluate potentially undesirable effects of these particles when administered intentionally for medical purposes. Therefore, there is a pressing need for careful consideration of benefits and side effects of the use of nanoparticles in medicine. This review article aims at providing a balanced update of these exciting pharmacological and potentially toxicological developments. The classes of nanoparticles, the current status of nanoparticle use in pharmacology and therapeutics, the demonstrated and potential toxicity of nanoparticles will be discussed. PMID:17245366

  1. Thermally stable nanoparticles on supports

    DOEpatents

    Roldan Cuenya, Beatriz; Naitabdi, Ahmed R.; Behafarid, Farzad

    2012-11-13

    An inverse micelle-based method for forming nanoparticles on supports includes dissolving a polymeric material in a solvent to provide a micelle solution. A nanoparticle source is dissolved in the micelle solution. A plurality of micelles having a nanoparticle in their core and an outer polymeric coating layer are formed in the micelle solution. The micelles are applied to a support. The polymeric coating layer is then removed from the micelles to expose the nanoparticles. A supported catalyst includes a nanocrystalline powder, thin film, or single crystal support. Metal nanoparticles having a median size from 0.5 nm to 25 nm, a size distribution having a standard deviation .ltoreq.0.1 of their median size are on or embedded in the support. The plurality of metal nanoparticles are dispersed and in a periodic arrangement. The metal nanoparticles maintain their periodic arrangement and size distribution following heat treatments of at least 1,000.degree. C.

  2. Nanoparticle-Based Biosensors and Bioassays

    SciTech Connect

    Liu, Guodong; Wang, Jun; Lin, Yuehe; Wang, Joseph

    2007-10-11

    In this book chapter, we review the recent advances in nanoparticles based bioassay. The nanoparticles include quantum dots, silica nanoparticles and apoferritin nanoparticles. The new nanoparticles-based labels hold great promise for multiplex protein and DNA detection and for enhancing the sensitivity of other bioassays.

  3. Nanoparticles in forensic science

    NASA Astrophysics Data System (ADS)

    Cantu, Antonio A.

    2008-10-01

    Nanoparticles appear in several areas of forensic science including security documents, paints, inks, and reagents that develop latent prints. One reagent (known as the silver physical developer) that visualizes the water insoluble components of latent print residue is based on the formation of highly charged silver nanoparticles. These attach to and grow on the residue and generate a silver image. Another such reagent involves highly charged gold nanoparticles. These attach to the residue forming a weak gold image which can be amplified with a silver physical developer. Nanoparaticles are also used in items such as paints, printing inks, and writing inks. Paints and most printing inks consist of nano-sized pigments in a vehicle. However, certain modern ink jet printing inks now contain nano-sized pigments to improve their light fastness and most gel inks are also based on nano scale pigments. These nanoparticlecontaining materials often appear as evidence and are thus subject to forensic characterization. Both luminescent (quantum dots), up-converting nano scale phosphors, and non luminescent nanoparticles are used as security tags to label product, add security to documents, and as anti counterfeiting measures. These assist in determining if an item is fraudulently made.

  4. Starch nanoparticles: a review.

    PubMed

    Le Corre, Déborah; Bras, Julien; Dufresne, Alain

    2010-05-10

    Starch is a natural, renewable, and biodegradable polymer produced by many plants as a source of stored energy. It is the second most abundant biomass material in nature. The starch structure has been under research for years, and because of its complexity, an universally accepted model is still lacking (Buleon, A.; et al. Int. J. Biol. Macromol. 1998, 23, 85-112). However, the predominant model for starch is a concentric semicrystalline multiscale structure that allows the production of new nanoelements: (i) starch nanocrystals resulting from the disruption of amorphous domains from semicrystalline granules by acid hydrolysis and (ii) starch nanoparticles produced from gelatinized starch. This paper intends to give a clear overview of starch nanoparticle preparation, characterization, properties, and applications. Recent studies have shown that they could be used as fillers to improve mechanical and barrier properties of biocomposites. Their use for industrial packaging, continuously looking for innovative solutions for efficient and sustainable systems, is being investigated. Therefore, recently, starch nanoparticles have been the focus of an exponentially increasing number of works devoted to develop biocomposites by blending starch nanoparticles with different biopolymeric matrices. To our knowledge, this topic has never been reviewed, despite several published strategies and conclusions. PMID:20405913

  5. Nanoparticles as biochemical sensors

    PubMed Central

    El-Ansary, Afaf; Faddah, Layla M

    2010-01-01

    There is little doubt that nanoparticles offer real and new opportunities in many fields, such as biomedicine and materials science. Such particles are small enough to enter almost all areas of the body, including cells and organelles, potentially leading to new approaches in nanomedicine. Sensors for small molecules of biochemical interest are of critical importance. This review is an attempt to trace the use of nanomaterials in biochemical sensor design. The possibility of using nanoparticles functionalized with antibodies as markers for proteins will be elucidated. Moreover, capabilities and applications for nanoparticles based on gold, silver, magnetic, and semiconductor materials (quantum dots), used in optical (absorbance, luminescence, surface enhanced Raman spectroscopy, surface plasmon resonance), electrochemical, and mass-sensitive sensors will be highlighted. The unique ability of nanosensors to improve the analysis of biochemical fluids is discussed either through considering the use of nanoparticles for in vitro molecular diagnosis, or in the biological/biochemical analysis for in vivo interaction with the human body. PMID:24198472

  6. Biotemplated magnetic nanoparticle arrays.

    PubMed

    Galloway, Johanna M; Bramble, Jonathan P; Rawlings, Andrea E; Burnell, Gavin; Evans, Stephen D; Staniland, Sarah S

    2012-01-23

    Immobilized biomineralizing protein Mms6 templates the formation of uniform magnetite nanoparticles in situ when selectively patterned onto a surface. Magnetic force microscopy shows that the stable magnetite particles maintain their magnetic orientation at room temperature, and may be exchange coupled. This precision-mixed biomimetic/soft-lithography methodology offers great potential for the future of nanodevice fabrication. PMID:22052737

  7. Asymmetric Hybrid Nanoparticles

    SciTech Connect

    Chumanov, George

    2015-11-05

    Hybrid Nanoparticles (AHNs) are rationally-designed multifunctional nanostructures and novel building blocks for the next generation of advanced materials and devices. Nanoscale materials attract considerable interest because of their unusual properties and potential for practical applications. Most of the activity in this field is focused on the synthesis of homogeneous nanoparticles from metals, metal oxides, semiconductors, and polymers. It is well recognized that properties of nanoparticles can be further enhanced if they are made as hybrid structures. This program is concerned with the synthesis, characterization, and application of such hybrid structures termed AHNs. AHNs are composed of a homogeneous core and several caps of different materials deposited on its surface (Fig. 1). Combined properties of the core and the caps as well as new properties that arise from core-cap and cap-cap interactions render AHNs multifunctional. In addition, specific chemical reactivity of the caps enables directional self-assembly of AHNs into complex architectures that are not possible with only spherical nanoparticles.

  8. DNA templated magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Kinsella, Joseph M.

    Recent discoveries in nanoscience are predicted to potentially revolutionize future technologies in an extensive number of fields. These developments are contingent upon discovering new and often unconventional methods to synthesize and control nanoscale components. Nature provides several examples of working nanotechnology such as the use of programmed self assembly to build and deconstruct complex molecular systems. We have adopted a method to control the one dimensional assembly of magnetic nanoparticles using DNA as a scaffold molecule. With this method we have demonstrated the ability to organize 5 nm particles into chains that stretch up to ˜20 mum in length. One advantage of using DNA compared is the ability of the molecule to interact with other biomolecules. After assembling particles onto DNA we have been able to cleave the molecule into smaller fragments using restriction enzymes. Using ligase enzymes we have re-connected these fragments, coated with either gold or iron oxide, to form long one-dimensional arrangements of the two different types of nanoparticles on a single molecular guide. We have also created a sensitive magnetic field sensor by incorporating magnetic nanoparticle coated DNA strands with microfabricated electrodes. The IV characteristics of the aligned nanoparticles are dependant on the magnitude of an externally applied magnetic field. This transport phenomenon known as tunneling magnetoresistance (TMR) shows room temperature resistance of our devices over 80% for cobalt ferrite coated DNA when a field of 20 kOe is applied. In comparison, studies using two dimensional nanoparticle films of irox oxides xii only exhibit a 35% MR effect. Confinement into one dimension using the DNA guide produces a TMR mechanism which produces significant increases in magnetoresistance. This property can be utilized for applications in magnetic field sensing, data storage, and logic elements.

  9. Book Review: The future of spacetime. Stephen William Hawking (ed.); Kip S. Thorne, Igor Novikov, Timothy Ferris, Alan Lightman, and Richard Price, W.W. Norton & Company, 2002, 224 pp., US 25.95, ISBN 0393020223

    NASA Astrophysics Data System (ADS)

    Smeenk, Chris

    The study of Einstein's theory of general relativity experienced a renaissance beginning in the early 1960s. Prior to this resurgence of interest, general relativity was isolated from mainstream physics-admired for its elegance, perhaps, but only from a distance. The generation of students who risked their careers by entering this neglected field has now reached the age of festschrifts. In June of 2000, Caltech hosted "Kipfest," a conference in honor of Kip Thorne's 60th birthday. Thorne started graduate school at Princeton in 1962 and began research in general relativity under John Wheeler's guidance in the heady early days of the renaissance. Since then, he has played a prominent role in general relativity: as co-author of the influential textbook Gravitation, as a leader in research regarding astrophysical applications of Einstein's theory, and as a co-founder and chief advocate for the Laser Interferometer Gravitational Wave Observatory (LIGO), to mention a few aspects of his far-reaching work. "Kipfest" included 14 speakers discussing fields to which Thorne has contributed. But the conference also reflected Thorne's long-standing commitment to communicating science to a general audience: Igor Novikov, Stephen Hawking, Timothy Ferris, and Alan Lightman gave popular talks at "Kipfest," with Thorne himself tricked into delivering a fifth. The Future of Spacetime gathers adaptations of these five lectures, along with a lengthy introductory essay by Richard Price.

  10. Magnetoacoustic Sensing of Magnetic Nanoparticles.

    PubMed

    Kellnberger, Stephan; Rosenthal, Amir; Myklatun, Ahne; Westmeyer, Gil G; Sergiadis, George; Ntziachristos, Vasilis

    2016-03-11

    The interaction of magnetic nanoparticles and electromagnetic fields can be determined through electrical signal induction in coils due to magnetization. However, the direct measurement of instant electromagnetic energy absorption by magnetic nanoparticles, as it relates to particle characterization or magnetic hyperthermia studies, has not been possible so far. We introduce the theory of magnetoacoustics, predicting the existence of second harmonic pressure waves from magnetic nanoparticles due to energy absorption from continuously modulated alternating magnetic fields. We then describe the first magnetoacoustic system reported, based on a fiber-interferometer pressure detector, necessary for avoiding electric interference. The magnetoacoustic system confirmed the existence of previously unobserved second harmonic magnetoacoustic responses from solids, magnetic nanoparticles, and nanoparticle-loaded cells, exposed to continuous wave magnetic fields at different frequencies. We discuss how magnetoacoustic signals can be employed as a nanoparticle or magnetic field sensor for biomedical and environmental applications. PMID:27015511

  11. Magnetoacoustic Sensing of Magnetic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Kellnberger, Stephan; Rosenthal, Amir; Myklatun, Ahne; Westmeyer, Gil G.; Sergiadis, George; Ntziachristos, Vasilis

    2016-03-01

    The interaction of magnetic nanoparticles and electromagnetic fields can be determined through electrical signal induction in coils due to magnetization. However, the direct measurement of instant electromagnetic energy absorption by magnetic nanoparticles, as it relates to particle characterization or magnetic hyperthermia studies, has not been possible so far. We introduce the theory of magnetoacoustics, predicting the existence of second harmonic pressure waves from magnetic nanoparticles due to energy absorption from continuously modulated alternating magnetic fields. We then describe the first magnetoacoustic system reported, based on a fiber-interferometer pressure detector, necessary for avoiding electric interference. The magnetoacoustic system confirmed the existence of previously unobserved second harmonic magnetoacoustic responses from solids, magnetic nanoparticles, and nanoparticle-loaded cells, exposed to continuous wave magnetic fields at different frequencies. We discuss how magnetoacoustic signals can be employed as a nanoparticle or magnetic field sensor for biomedical and environmental applications.

  12. Progress toward clonable inorganic nanoparticles

    NASA Astrophysics Data System (ADS)

    Ni, Thomas W.; Staicu, Lucian C.; Nemeth, Richard S.; Schwartz, Cindi L.; Crawford, David; Seligman, Jeffrey D.; Hunter, William J.; Pilon-Smits, Elizabeth A. H.; Ackerson, Christopher J.

    2015-10-01

    Pseudomonas moraviensis stanleyae was recently isolated from the roots of the selenium (Se) hyperaccumulator plant Stanleya pinnata. This bacterium tolerates normally lethal concentrations of SeO32- in liquid culture, where it also produces Se nanoparticles. Structure and cellular ultrastructure of the Se nanoparticles as determined by cellular electron tomography shows the nanoparticles as intracellular, of narrow dispersity, symmetrically irregular and without any observable membrane or structured protein shell. Protein mass spectrometry of a fractionated soluble cytosolic material with selenite reducing capability identified nitrite reductase and glutathione reductase homologues as NADPH dependent candidate enzymes for the reduction of selenite to zerovalent Se nanoparticles. In vitro experiments with commercially sourced glutathione reductase revealed that the enzyme can reduce SeO32- (selenite) to Se nanoparticles in an NADPH-dependent process. The disappearance of the enzyme as determined by protein assay during nanoparticle formation suggests that glutathione reductase is associated with or possibly entombed in the nanoparticles whose formation it catalyzes. Chemically dissolving the nanoparticles releases the enzyme. The size of the nanoparticles varies with SeO32- concentration, varying in size form 5 nm diameter when formed at 1.0 μM [SeO32-] to 50 nm maximum diameter when formed at 100 μM [SeO32-]. In aggregate, we suggest that glutathione reductase possesses the key attributes of a clonable nanoparticle system: ion reduction, nanoparticle retention and size control of the nanoparticle at the enzyme site.Pseudomonas moraviensis stanleyae was recently isolated from the roots of the selenium (Se) hyperaccumulator plant Stanleya pinnata. This bacterium tolerates normally lethal concentrations of SeO32- in liquid culture, where it also produces Se nanoparticles. Structure and cellular ultrastructure of the Se nanoparticles as determined by cellular

  13. Harnessing nanoparticles for immune modulation

    PubMed Central

    Getts, Daniel R.; Shea, Lonnie D; Miller, Stephen D.; King, Nicholas J.C.

    2015-01-01

    Recent approaches using nanoparticles engineered for immune regulation have yielded promising results in preclinical models of disease. The number of nanoparticle therapies is growing, fueled by innovations in nanotechnology and advances in understanding of the underlying pathogenesis of immune-mediated diseases. In particular, recent mechanistic insight into the ways in which nanoparticles interact with the mononuclear phagocyte system and impact its function during homeostasis and inflammation have highlighted the potential of nanoparticle-based therapies for controlling severe inflammation while concurrently restoring peripheral immune tolerance in autoimmune disease. Here we review recent advances in nanoparticle-based approaches aimed at immune-modulation, and discuss these in the context of concepts in polymeric nanoparticle development, including particle modification, delivery and the factors associated with successful clinical deployment. PMID:26088391

  14. Safety of Nanoparticles in Medicine.

    PubMed

    Wolfram, Joy; Zhu, Motao; Yang, Yong; Shen, Jianliang; Gentile, Emanuela; Paolino, Donatella; Fresta, Massimo; Nie, Guangjun; Chen, Chunying; Shen, Haifa; Ferrari, Mauro; Zhao, Yuliang

    2015-01-01

    Nanomedicine involves the use of nanoparticles for therapeutic and diagnostic purposes. During the past two decades, a growing number of nanomedicines have received regulatory approval and many more show promise for future clinical translation. In this context, it is important to evaluate the safety of nanoparticles in order to achieve biocompatibility and desired activity. However, it is unwarranted to make generalized statements regarding the safety of nanoparticles, since the field of nanomedicine comprises a multitude of different manufactured nanoparticles made from various materials. Indeed, several nanotherapeutics that are currently approved, such as Doxil and Abraxane, exhibit fewer side effects than their small molecule counterparts, while other nanoparticles (e.g. metallic and carbon-based particles) tend to display toxicity. However, the hazardous nature of certain nanomedicines could be exploited for the ablation of diseased tissue, if selective targeting can be achieved. This review discusses the mechanisms for molecular, cellular, organ, and immune system toxicity, which can be observed with a subset of nanoparticles. Strategies for improving the safety of nanoparticles by surface modification and pretreatment with immunomodulators are also discussed. Additionally, important considerations for nanoparticle safety assessment are reviewed. In regards to clinical application, stricter regulations for the approval of nanomedicines might not be required. Rather, safety evaluation assays should be adjusted to be more appropriate for engineered nanoparticles. PMID:26601723

  15. Silver Nanoparticles in Dental Biomaterials

    PubMed Central

    Corrêa, Juliana Mattos; Mori, Matsuyoshi; Sanches, Heloísa Lajas; da Cruz, Adriana Dibo; Poiate, Isis Andréa Venturini Pola

    2015-01-01

    Silver has been used in medicine for centuries because of its antimicrobial properties. More recently, silver nanoparticles have been synthesized and incorporated into several biomaterials, since their small size provides great antimicrobial effect, at low filler level. Hence, these nanoparticles have been applied in dentistry, in order to prevent or reduce biofilm formation over dental materials surfaces. This review aims to discuss the current progress in this field, highlighting aspects regarding silver nanoparticles incorporation, such as antimicrobial potential, mechanical properties, cytotoxicity, and long-term effectiveness. We also emphasize the need for more studies to determine the optimal concentration of silver nanoparticle and its release over time. PMID:25667594

  16. Magnetic Nanoparticle Sensors

    PubMed Central

    Koh, Isaac; Josephson, Lee

    2009-01-01

    Many types of biosensors employ magnetic nanoparticles (diameter = 5–300 nm) or magnetic particles (diameter = 300–5,000 nm) which have been surface functionalized to recognize specific molecular targets. Here we cover three types of biosensors that employ different biosensing principles, magnetic materials, and instrumentation. The first type consists of magnetic relaxation switch assay-sensors, which are based on the effects magnetic particles exert on water proton relaxation rates. The second type consists of magnetic particle relaxation sensors, which determine the relaxation of the magnetic moment within the magnetic particle. The third type is magnetoresistive sensors, which detect the presence of magnetic particles on the surface of electronic devices that are sensitive to changes in magnetic fields on their surface. Recent improvements in the design of magnetic nanoparticles (and magnetic particles), together with improvements in instrumentation, suggest that magnetic material-based biosensors may become widely used in the future. PMID:22408498

  17. Nanoparticles for neuroimaging

    NASA Astrophysics Data System (ADS)

    Re, F.; Moresco, R.; Masserini, M.

    2012-02-01

    The advent of nanotechnology has introduced a variety of novel exciting possibilities into the medical and clinical field. Nanoparticles, ultra-small object sized between 100 and 1 nm, are promising diagnostic tools for various diseases among other devices, thanks to the possibility of their functionalization allowing the selective targeting of organs, tissues and cells and to facilitate their transport to primary target organs. However, brain targeting represents a still unresolved challenge due to the presence of the blood-brain barrier, a tightly packed layer of endothelial cells that prevents unwanted substances entering the central nervous system. We review a range of nanoparticles suitable for in vivo diagnostic imaging of neurodegenerative diseases and brain disorders, highlighting the possibility to potentially increase their efficiency and kinetics of brain-targeting. We also review a range of imaging techniques with an emphasis on most recently introduced molecular imaging modalities, their current status and future potential.

  18. Nanoparticle Reactions on Chip

    NASA Astrophysics Data System (ADS)

    Köhler, J. M.; Kirner, Th.; Wagner, J.; Csáki, A.; Möller, R.; Fritzsche, W.

    The handling of heterogenous systems in micro reactors is difficult due to their adhesion and transport behaviour. Therefore, the formation of precipitates and gas bubbles has to be avoided in micro reaction technology, in most cases. But, micro channels and other micro reactors offer interesting possibilities for the control of reaction conditions and transport by diffusion and convection due to the laminar flow caused by small Reynolds numbers. This can be used for the preparation and modification of objects, which are much smaller than the cross section of microchannels. The formation of colloidal solutions and the change of surface states of nano particles are two important tasks for the application of chip reactors in nanoparticle technology. Some concepts for the preparation and reaction of nanoparticles in modular chip reactor arrangements will be discussed.

  19. Metallic nanoparticles meet metadynamics

    NASA Astrophysics Data System (ADS)

    Pavan, L.; Rossi, K.; Baletto, F.

    2015-11-01

    Metadynamics coupled with classical molecular dynamics has been successfully applied to sample the configuration space of metallic and bimetallic nanoclusters. We implement a new set of collective variables related to the pair distance distribution function of the nanoparticle to achieve an exhaustive isomer sampling. As paradigmatic examples, we apply our methodology to Ag147, Pt147, and their alloy AgshellPtcore at 2:1 and 1:1 chemical compositions. The proposed scheme is able to reproduce the known solid-solid structural transformation pathways, based on the Lipscomb's diamond-square-diamond mechanisms, both in mono and bimetallic nanoparticles. A discussion of the free energy barriers involved in these processes is provided.

  20. Hydrogel nanoparticle based immunoassay

    DOEpatents

    Liotta, Lance A; Luchini, Alessandra; Petricoin, Emanuel F; Espina, Virginia

    2015-04-21

    An immunoassay device incorporating porous polymeric capture nanoparticles within either the sample collection vessel or pre-impregnated into a porous substratum within fluid flow path of the analytical device is presented. This incorporation of capture particles within the immunoassay device improves sensitivity while removing the requirement for pre-processing of samples prior to loading the immunoassay device. A preferred embodiment is coreshell bait containing capture nanoparticles which perform three functions in one step, in solution: a) molecular size sieving, b) target analyte sequestration and concentration, and c) protection from degradation. The polymeric matrix of the capture particles may be made of co-polymeric materials having a structural monomer and an affinity monomer, the affinity monomer having properties that attract the analyte to the capture particle. This device is useful for point of care diagnostic assays for biomedical applications and as field deployable assays for environmental, pathogen and chemical or biological threat identification.

  1. Evaluation of nanoparticle immunotoxicity

    NASA Astrophysics Data System (ADS)

    Dobrovolskaia, Marina A.; Germolec, Dori R.; Weaver, James L.

    2009-07-01

    The pharmaceutical industry is developing increasing numbers of drugs and diagnostics based on nanoparticles, and evaluating the immune response to these diverse formulations has become a challenge for scientists and regulatory agencies alike. An international panel of scientists and representatives from various agencies and companies reviewed the imitations of current tests at a workshop held at the National Cancer Institute in Frederick, Maryland. This article outlines practical strategies for identifying and controlling interferences in common evaluation methods and the implications for regulation.

  2. Characterization of starch nanoparticles

    NASA Astrophysics Data System (ADS)

    Szymońska, J.; Targosz-Korecka, M.; Krok, F.

    2009-01-01

    Nanomaterials already attract great interest because of their potential applications in technology, food science and medicine. Biomaterials are biodegradable and quite abundant in nature, so they are favoured over synthetic polymer based materials. Starch as a nontoxic, cheap and renewable raw material is particularly suitable for preparation of nanoparticles. In the paper, the structure and some physicochemical properties of potato and cassava starch particles of the size between 50 to 100 nm, obtained by mechanical treatment of native starch, were presented. We demonstrated, with the aim of the Scanning Electron Microscopy (SEM) and the non-contact Atomic Force Microscopy (nc-AFM), that the shape and dimensions of the obtained nanoparticles both potato and cassava starch fit the blocklets - previously proposed as basic structural features of native starch granules. This observation was supported by aqueous solubility and swelling power of the particles as well as their iodine binding capacity similar to those for amylopectin-type short branched polysaccharide species. Obtained results indicated that glycosidic bonds of the branch linkage points in the granule amorphous lamellae might be broken during the applied mechanical treatment. Thus the released amylopectin clusters could escape out of the granules. The starch nanoparticles, for their properties qualitatively different from those of native starch granules, could be utilized in new applications.

  3. Gluing Soft Interfaces by Nanoparticles

    NASA Astrophysics Data System (ADS)

    Cao, Zhen; Dobrynin, Andrey

    Using a combination of the molecular dynamics simulations and scaling analysis we studied reinforcement of interface between two soft gel-like materials by spherical nanoparticles. Analysis of the simulations shows that the depth of penetration of a nanoparticle into a gel is determined by a balance of the elastic energy of the gel and nanoparticle deformations and the surface energy of nanoparticle/gel interface. In order to evaluate work of adhesion of the reinforced interface, the potential of mean force for separation of two gels was calculated. These simulations showed that the gel separation proceeds through formation of necks connecting nanoparticle with two gels. The shapes of the necks are controlled by a fine interplay between nanoparticle/gel surface energies and elastic energy of the neck deformation. Our simulations showed that by introducing nanoparticles at soft interfaces, the work required for separation of two gels could be 10-100 times larger than the work of adhesion between two gels without nanoparticle reinforcement. These results provide insight in understanding the mechanism of gluing soft gels and biological tissues by nano- and micro-sized particles. NSF DMR-1409710.

  4. MICROBIAL IMPACTS OF ENGINEERED NANOPARTICLES

    EPA Science Inventory

    Reactivity at the nanometric scale is intimately linked to nanoparticle mobility and microbial sensitivity. Thus, first-order factors increasing nanoparticle reactivity should increase the rate of redox reactions with second-order effects on particle mobility and ecot...

  5. Thermal treatment of magnetite nanoparticles

    PubMed Central

    Wykowska, Urszula; Satula, Dariusz; Nordblad, Per

    2015-01-01

    Summary This paper presents the results of a thermal treatment process for magnetite nanoparticles in the temperature range of 50–500 °C. The tested magnetite nanoparticles were synthesized using three different methods that resulted in nanoparticles with different surface characteristics and crystallinity, which in turn, was reflected in their thermal durability. The particles were obtained by coprecipitation from Fe chlorides and decomposition of an Fe(acac)3 complex with and without a core–shell structure. Three types of ferrite nanoparticles were produced and their thermal stability properties were compared. In this study, two sets of unmodified magnetite nanoparticles were used where crystallinity was as determinant of the series. For the third type of particles, a Ag shell was added. By comparing the coated and uncoated particles, the influence of the metallic layer on the thermal stability of the nanoparticles was tested. Before and after heat treatment, the nanoparticles were examined using transmission electron microscopy, IR spectroscopy, differential scanning calorimetry, X-ray diffraction and Mössbauer spectroscopy. Based on the obtained results, it was observed that the fabrication methods determine, to some extent, the sensitivity of the nanoparticles to external factors. PMID:26199842

  6. Responsive foams for nanoparticle delivery.

    PubMed

    Tang, Christina; Xiao, Edward; Sinko, Patrick J; Szekely, Zoltan; Prud'homme, Robert K

    2015-09-01

    We have developed responsive foam systems for nanoparticle delivery. The foams are easy to make, stable at room temperature, and can be engineered to break in response to temperature or moisture. Temperature-responsive foams are based on the phase transition of long chain alcohols and could be produced using medical grade nitrous oxide as a propellant. These temperature-sensitive foams could be used for polyacrylic acid (PAA)-based nanoparticle delivery. We also discuss moisture-responsive foams made with soap pump dispensers. Polyethylene glycol (PEG)-based nanoparticles or PMMA latex nanoparticles were loaded into Tween 20 foams and the particle size was not affected by the foam formulation or foam break. Using biocompatible detergents, we anticipate this will be a versatile and simple approach to producing foams for nanoparticle delivery with many potential pharmaceutical and personal care applications. PMID:26091943

  7. Superabsorption of light by nanoparticles.

    PubMed

    Ladutenko, Konstantin; Belov, Pavel; Peña-Rodríguez, Ovidio; Mirzaei, Ali; Miroshnichenko, Andrey E; Shadrivov, Ilya V

    2015-12-01

    Nanoparticles have a fundamental limit as to how much light they can absorb. This limit is based on the finite number of modes excited in the nanoparticle at a given wavelength and maximum absorption capacity per mode. The enhanced absorption can be achieved when each mode supported by the nanoparticle absorbs light up to the maximum capacity. Using a stochastic optimization algorithm, we design multilayer nanoparticles, in which we can make several resonant modes overlap at the same frequency resulting in superabsorption. We further introduce the efficiency of the absorption for a nanoparticle, which is the absorption normalized by the physical size of the particle, and show that efficient absorbers do not always operate in the superabsorption regime. PMID:26531069

  8. Solventless synthesis of ruthenium nanoparticles

    NASA Astrophysics Data System (ADS)

    García-Peña, Nidia G.; Redón, Rocío; Herrera-Gomez, Alberto; Fernández-Osorio, Ana Leticia; Bravo-Sanchez, Mariela; Gomez-Sosa, Gustavo

    2015-06-01

    This paper presents a novel solventless method for the synthesis of zero-valent ruthenium nanoparticles Ru(0). The proposed method, although not entirely new in the nanomaterials world, was used for the first time to synthesize zero-valent ruthenium nanoparticles. This new approach has proved to be an environmentally friendly, clean, cheap, fast, and reproducible technique which employs low amounts of solvent. It was optimized through varying amounts of reducing salt on a determined quantity of precursor and measuring the effect of this variation on the average particle size obtained. The resulting products were fully characterized by powder XRD, TEM, HR-TEM, and XPS studies, all of which corroborated the purity of the nanoparticles achieved. In order to verify the advantages of our method over other techniques, we compared our nanoparticles with two common colloidal-synthesized ruthenium nanoparticles.

  9. Stress-Induced Nanoparticle Crystallization

    PubMed Central

    2015-01-01

    We demonstrate for the first time a new mechanical annealing method that can significantly improve the structural quality of self-assembled nanoparticle arrays by eliminating defects at room temperature. Using in situ high-pressure small-angle X-ray scattering, we show that deformation of nanoparticle assembly in the presence of gigapascal level stress rebalances interparticle forces within nanoparticle arrays and transforms the nanoparticle film from an amorphous assembly with defects into a quasi-single crystalline superstructure. Our results show that the existence of the hydrostatic pressure field makes the transformation both thermodynamically and kinetically possible/favorable, thus providing new insight for nanoparticle self-assembly and integration with enhanced mechanical performance. PMID:24829089

  10. Host thin films incorporating nanoparticles

    NASA Astrophysics Data System (ADS)

    Qureshi, Uzma

    The focus of this research project was the investigation of the functional properties of thin films that incorporate a secondary nanoparticulate phase. In particular to assess if the secondary nanoparticulate material enhanced a functional property of the coating on glass. In order to achieve this, new thin film deposition methods were developed, namely use of nanopowder precursors, an aerosol assisted transport technique and an aerosol into atmospheric pressure chemical vapour deposition system. Aerosol assisted chemical vapour deposition (AACVD) was used to deposit 8 series of thin films on glass. Five different nanoparticles silver, gold, ceria, tungsten oxide and zinc oxide were tested and shown to successfully deposit thin films incorporating nanoparticles within a host matrix. Silver nanoparticles were synthesised and doped within a titania film by AACVD. This improved solar control properties. A unique aerosol assisted chemical vapour deposition (AACVD) into atmospheric pressure chemical vapour deposition (APCVD) system was used to deposit films of Au nanoparticles and thin films of gold nanoparticles incorporated within a host titania matrix. Incorporation of high refractive index contrast metal oxide particles within a host film altered the film colour. The key goal was to test the potential of nanopowder forms and transfer the suspended nanopowder via an aerosol to a substrate in order to deposit a thin film. Discrete tungsten oxide nanoparticles or ceria nanoparticles within a titanium dioxide thin film enhanced the self-cleaning and photo-induced super-hydrophilicity. The nanopowder precursor study was extended by deposition of zinc oxide thin films incorporating Au nanoparticles and also ZnO films deposited from a ZnO nanopowder precursor. Incorporation of Au nanoparticles within a VO: host matrix improved the thermochromic response, optical and colour properties. Composite VC/TiC and Au nanoparticle/V02/Ti02 thin films displayed three useful

  11. Carcinogenicity of inhaled nanoparticles.

    PubMed

    Roller, Markus

    2009-07-01

    Large epidemiological studies in the United States have shown a statistical association between air concentration of the fine dust fraction PM(2.5) in the general environment and increased risk of lung cancer. A quantitative risk assessment for lung cancer based on these studies corresponds to risk estimates based on studies at workplaces with exposure to diesel engine emissions; its magnitude cannot be explained by the known carcinogenicity of organic substances or metals adsorbed to the insoluble particle core. Carcinogenic effects of diesel particles were observed after inhalation in rats independently in several studies. The surprisingly strong effect of diesel particles was partially attributed to their small size. This hypothesis was corroborated by inhalation studies with synthetic nanoparticles virtually free of organic compounds. IARC found sufficient evidence for the carcinogenicity of carbon black and of titanium dioxide in experimental animals. Long-term studies by the method of intratracheal instillation confirmed the carcinogenic effects in rats for an even broader spectrum of synthetic nanoparticles. Non-positive studies with hamsters are not valid because hamsters did not develop lung tumors after inhalation of some known human carcinogens. In recent years, the number of publications reporting in vitro genotoxicity of TiO(2) and of carbon black nanomaterials has increased. Overall, there is clear positive evidence for carcinogenicity in rats, together with supporting evidence from human data of structurally related substances. Therefore, the European Union (EU) criteria for category 2 of carcinogenic substances appear to be fulfilled for bio-durable nanoparticles consisting of matter without known significant specific toxicity. PMID:19558247

  12. Antibacterial properties of nanoparticles.

    PubMed

    Hajipour, Mohammad J; Fromm, Katharina M; Ashkarran, Ali Akbar; Jimenez de Aberasturi, Dorleta; de Larramendi, Idoia Ruiz; Rojo, Teofilo; Serpooshan, Vahid; Parak, Wolfgang J; Mahmoudi, Morteza

    2012-10-01

    Antibacterial agents are very important in the textile industry, water disinfection, medicine, and food packaging. Organic compounds used for disinfection have some disadvantages, including toxicity to the human body, therefore, the interest in inorganic disinfectants such as metal oxide nanoparticles (NPs) is increasing. This review focuses on the properties and applications of inorganic nanostructured materials and their surface modifications, with good antimicrobial activity. Such improved antibacterial agents locally destroy bacteria, without being toxic to the surrounding tissue. We also provide an overview of opportunities and risks of using NPs as antibacterial agents. In particular, we discuss the role of different NP materials. PMID:22884769

  13. Nanoparticle enhanced ionic liquid heat transfer fluids

    DOEpatents

    Fox, Elise B.; Visser, Ann E.; Bridges, Nicholas J.; Gray, Joshua R.; Garcia-Diaz, Brenda L.

    2014-08-12

    A heat transfer fluid created from nanoparticles that are dispersed into an ionic liquid is provided. Small volumes of nanoparticles are created from e.g., metals or metal oxides and/or alloys of such materials are dispersed into ionic liquids to create a heat transfer fluid. The nanoparticles can be dispersed directly into the ionic liquid during nanoparticle formation or the nanoparticles can be formed and then, in a subsequent step, dispersed into the ionic liquid using e.g., agitation.

  14. Synthesis of noble metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Bahadory, Mozhgan

    Improved methods were developed for the synthesis of noble metal nanoparticles. Laboratory experiments were designed for introducing of nanotechnology into the undergraduate curriculum. An optimal set of conditions for the synthesis of clear yellow colloidal silver was investigated. Silver nanoparticles were obtained by borohydride reduction of silver nitrate, a method which produces particles with average size of 12+/-2 nm, determined by Transmission Electron Microscopy (TEM). The plasmon absorbance is at 397 nm and the peak width at half maximum (PWHM) is 70-75 nm. The relationship between aggregation and optical properties was determined along with a method to protect the particles using polyvinylpyrrolidone (PVP). A laboratory experiment was designed in which students synthesize yellow colloidal silver, estimate particle size using visible spectroscopy, and study aggregation effects. The synthesis of the less stable copper nanoparticles is more difficult because copper nanopaticles are easily oxidized. Four methods were used for the synthesis of copper nanoparticles, including chemical reduction with sodium borohydride, sodium borohydride with potassium iodide, isopropyl alcohol with cetyltrimethylammonium bormide (CTAB) and reducing sugars. The latter method was also the basis for an undergraduate laboratory experiment. For each reaction, the dependence of stability of the copper nanoparticles on reagent concentrations, additives, relative amounts of reactants, and temperature is explored. Atomic force microscopy (AFM), TEM and UV-Visible Spectroscopy were used to characterize the copper nanoparticles. A laboratory experiment to produce copper nanoparticles from household chemicals was developed.

  15. Nanoparticles in dermatology.

    PubMed

    Papakostas, Dimitrios; Rancan, Fiorenza; Sterry, Wolfram; Blume-Peytavi, Ulrike; Vogt, Annika

    2011-10-01

    Recent advances in the field of nanotechnology have allowed the manufacturing of elaborated nanometer-sized particles for various biomedical applications. A broad spectrum of particles, extending from various lipid nanostructures such as liposomes and solid lipid nanoparticles, to metal, nanocrystalline and polymer particles have already been tested as drug delivery systems in different animal models with remarkable results, promising an extensive commercialization in the coming years. Controlled drug release to skin and skin appendages, targeting of hair follicle-specific cell populations, transcutaneous vaccination and transdermal gene therapy are only a few of these new applications. Carrier systems of the new generation take advantage of improved skin penetration properties, depot effect with sustained drug release and of surface functionalization (e.g., the binding to specific ligands) allowing specific cellular and subcellular targeting. Drug delivery to skin by means of microparticles and nanocarriers could revolutionize the treatment of several skin disorders. However, the toxicological and environmental safety of micro- and nanoparticles has to be evaluated using specific toxicological studies prior to a wider implementation of the new technology. This review aims to give an overview of the most investigated applications of transcutaneously applied particle-based formulations in the fields of cosmetics and dermatology. PMID:21837474

  16. Nanoparticle optical notch filters

    NASA Astrophysics Data System (ADS)

    Kasinadhuni, Pradeep Kumar

    Developing novel light blocking products involves the design of a nanoparticle optical notch filter, working on the principle of localized surface plasmon resonance (LSPR). These light blocking products can be used in many applications. One such application is to naturally reduce migraine headaches and light sensitivity. Melanopsin ganglion cells present in the retina of the human eye, connect to the suprachiasmatic nucleus (SCN-the body's clock) in the brain, where they participate in the entrainment of the circadian rhythms. As the Melanopsin ganglion cells are involved in triggering the migraine headaches in photophobic patients, it is necessary to block the part of visible spectrum that activates these cells. It is observed from the action potential spectrum of the ganglion cells that they absorb light ranging from 450-500nm (blue-green part) of the visible spectrum with a λmax (peak sensitivity) of around 480nm (blue line). Currently prescribed for migraine patients is the FL-41 coating, which blocks a broad range of wavelengths, including wavelengths associated with melanopsin absorption. The nanoparticle optical notch filter is designed to block light only at 480nm, hence offering an effective prescription for the treatment of migraine headaches.

  17. Method of synthesizing tungsten nanoparticles

    DOEpatents

    Thoma, Steven G; Anderson, Travis M

    2013-02-12

    A method to synthesize tungsten nanoparticles has been developed that enables synthesis of nanometer-scale, monodisperse particles that can be stabilized only by tetrahydrofuran. The method can be used at room temperature, is scalable, and the product concentrated by standard means. Since no additives or stabilizing surfactants are required, this method is particularly well suited for producing tungsten nanoparticles for dispersion in polymers. If complete dispersion is achieved due to the size of the nanoparticles, then the optical properties of the polymer can be largely maintained.

  18. Inorganic Nanoparticles in Cancer Therapy

    PubMed Central

    Bhattacharyya, Sanjib; Kudgus, Rachel A.; Bhattacharya, Resham; Mukherjee, Priyabrata

    2011-01-01

    Nanotechnology is an evolving field with enormous potential for biomedical applications. The growing interest to use inorganic nanoparticles in medicine is due to the unique size and shape-dependent optoelectronic properties. Herein, we will focus on gold, silver and platinum nanoparticles, discussing recent developments for therapeutic applications with regard to cancer in terms of nanoparticles being used as a delivery vehicle as well as therapeutic agents. We will also discuss some of the key challenges to be addressed in future studies. PMID:21104301

  19. [Toxicity of nanoparticles on reproduction].

    PubMed

    Greco, F; Courbière, B; Rose, J; Orsière, T; Sari-Minodier, I; Bottero, J-Y; Auffan, M; Perrin, J

    2015-01-01

    Nanoparticles (NPs) are sized between 1 and 100nm. Their size allows new nanoscale properties of particular interest for industrial and scientific purpose. Over the past twenty years, nanotechnology conquered many areas of use (electronic, cosmetic, textile…). While, human is exposed to an increasing number of nanoparticles sources, health impacts and, particularly on reproductive function, remains poorly evaluated. Indeed, traceability of nanoparticles use is lacking and nanotoxicology follows different rules than classical toxicology. This review focuses on the impact of NPs on health and particularly on fertility and addresses potential risks of chronic exposure to NPs on human fertility. PMID:25533638

  20. The ALAN Review. Volume 9, No. 1.

    ERIC Educational Resources Information Center

    Ellis, W. Geiger, Ed.; Ward, Dan, Ed.

    1981-01-01

    The articles in this journal issue focus on adolescent literature. In the first article, author Sue Ellen Bridgers explains how she writes books, while the second article offers an analysis of the recent works of Paul Zindel. The third article presents a discussion of the treatment of outsiders, such as the mentally ill, in four Roy Brown…

  1. The ALAN Review. Volume 8, No. 1.

    ERIC Educational Resources Information Center

    Ellis, W. Geiger, Ed.; Ward, Dan, Ed.

    1980-01-01

    The articles in this journal issue focus on adolescent literature. Topics covered in the articles include: (1) teaching adolescent literature about minorities to majority group students, (2) death in adolescent literature, (3) trends in German youth literature, and (4) female identity in the young adult novel. In addition, the journal issue…

  2. Dynamics of nanoparticle combustion

    NASA Astrophysics Data System (ADS)

    Allen, David James

    A heterogeneous shock tube was used to ignite and measure the combustion behavior of the nano-aluminum suspension behind reflected shock waves. The burning time and particle temperatures were measured using optical diagnostics. In order to use pyrometry measurements for nano-aluminum particles, the emissivity of nano-alumina particles was also measured using the shock tube to heat the particles to known temperatures. The burning time and peak particle temperature results suggested that heat transfer models currently used for burning nanoparticles may significantly overestimate heat losses during combustion. By applying conventional non-continuum heat transfer correlations to burning nano-aluminum particles, the observed peak temperatures, which greatly exceed the ambient temperature, should only be observable if the burning time were very short, of the order of 1 mus, whereas the observed burning time is two orders of magnitude larger. These observations can be reconciled if the energy accommodation coefficient for these conditions is of the order of 0.005, which is the value suggested by Altman, instead of approximately unity, which is the common assumption. A simple model was developed for nano-aluminum particle combustion focusing on a surface controlled reaction as evidenced by experimental data and heat transfer to the surroundings. The simple model supports a low energy accommodation coefficient as suggested by Altman. This result has significant implications on the heat transfer and performance of the nanoparticles in combustion environments. Direct measurement is needed in order to decouple the accommodation coefficient from the assumed combustion mechanism in the simple model. Time-resolved laser induced incandescence measurements were performed to measure the accommodation coefficient of nano-alumina particles in various gaseous environments. The accommodation coefficient was found to be 0.03, 0.07, and 0.15 in helium, nitrogen, and argon respectively at

  3. Magnetocaloric effect in ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Poddar, P.; Gass, J.; Rebar, D. J.; Srinath, S.; Srikanth, H.; Morrison, S. A.; Carpenter, E. E.

    2006-12-01

    A comparative study of the magnetocaloric effect (MCE) is reported in two different types of chemically synthesized magnetic nanoparticle systems—cobalt ferrite and manganese zinc ferrite with mean size around 5 and 15 nm, respectively. While CoFe 2O 4 nanoparticles were synthesized using co-precipitation, the Mn 0.68Zn 0.25Fe 2.07O 4 (MZFO) nanoparticles were prepared by reverse micelle technique using AOT as surfactant. Our results indicate that the change in entropy with the change in applied magnetic field (d S/d H) is reasonably large for this class of nanoparticles and has a wide distribution over a broad temperature range covering the region above and below the blocking temperature. The maximum entropy change is influenced by the particle size, overall distribution in anisotropy and magnetic moments.

  4. Lipid nanoparticle interactions and assemblies

    NASA Astrophysics Data System (ADS)

    Preiss, Matthew Ryan

    Novel liposome-nanoparticle assemblies (LNAs) provide a biologically inspired route for designing multifunctional bionanotheranostics. LNAs combine the benefits of lipids and liposomes to encapsulate, transport, and protect hydrophilic and hydrophobic therapeutics with functional nanoparticles. Functional nanoparticles endow LNAs with additional capabilities, including the ability to target diseases, triggered drug release, controlled therapeutic output, and diagnostic capabilities to produce a drug delivery system that can effectively and efficiently deliver therapeutics while reducing side effects. Not only could LNAs make existing drugs better, they could also provide an avenue to allow once promising non-approved drugs (rejected due to harmful side effects, inadequate pharmacokinetics, and poor efficacy) to be safely used through targeted and controlled delivery directly to the diseased site. LNAs have the potential to be stimuli responsive, delivering drugs on command by external (ultrasound, RF heating, etc.) or internal (pH, blood sugar, heart rate, etc.) stimuli. Individually, lipids and nanoparticles have been clinically approved for therapy, such as Doxil (a liposomal doxorubicin for cancer treatment), and diagnosis, such as Feridex (an iron oxide nanoparticle an MRI contrast enhancement agent for liver tumors). In order to engineer these multifunctional LNAs for theranostic applications, the interactions between nanoparticles and lipids must be better understood. This research sought to explore the formation, design, structures, characteristics, and functions of LNAs. To achieve this goal, different types of LNAs were formed, specifically magnetoliposomes, bilayer decorated LNAs (DLNAs), and lipid-coated magnetic nanoparticles (LMNPs). A fluorescent probe was embedded in the lipid bilayer of magnetoliposomes allowing the local temperature and membrane fluidity to be observed. When subjected to an electromagnetic field that heated the encapsulated iron

  5. Targeted nanoparticles for colorectal cancer.

    PubMed

    Cisterna, Bruno A; Kamaly, Nazila; Choi, Won Il; Tavakkoli, Ali; Farokhzad, Omid C; Vilos, Cristian

    2016-09-01

    Colorectal cancer (CRC) is highly prevalent worldwide, and despite notable progress in treatment still leads to significant morbidity and mortality. The use of nanoparticles as a drug delivery system has become one of the most promising strategies for cancer therapy. Targeted nanoparticles could take advantage of differentially expressed molecules on the surface of tumor cells, providing effective release of cytotoxic drugs. Several efforts have recently reported the use of diverse molecules as ligands on the surface of nanoparticles to interact with the tumor cells, enabling the effective delivery of antitumor agents. Here, we present recent advances in targeted nanoparticles against CRC and discuss the promising use of ligands and cellular targets in potential strategies for the treatment of CRCs. PMID:27529192

  6. Pegylation increases platelet biocompatibility of gold nanoparticles.

    PubMed

    Santos-Martinez, Maria Jose; Rahme, Kamil; Corbalan, J Jose; Faulkner, Colm; Holmes, Justin D; Tajber, Lidia; Medina, Carlos; Radomski, Marek Witold

    2014-06-01

    The increasing use of gold nanoparticles in medical diagnosis and treatment has raised the concern over their blood compatibility. The interactions of nanoparticles with blood components may lead to platelet aggregation and endothelial dysfunction. Therefore, medical applications of gold nanoparticles call for increased nanoparticle stability and biocompatibility. Functionalisation of nanoparticles with polythelene glycol (PEGylation) is known to modulate cell-particle interactions. Therefore, the aim of the current study was to investigate the effects of PEGylated-gold nanoparticles on human platelet function and endothelial cells in vitro. Gold nanoparticles, 15 nm in diameter, were synthesised in water using sodium citrate as a reducing and stabilising agent. Functionalised polyethylene glycol-based thiol polymers were used to coat and stabilise pre-synthesised gold nanoparticles. The interaction of gold nanoparticles-citrate and PEGylated-gold nanoparticles with human platelets was measured by Quartz Crystal Microbalance with Dissipation. Platelet-nanoparticles interaction was imaged using phase-contrast, scanning and transmission electron microscopy. The inflammatory effects of gold nanoparticles-citrate and PEGylated-gold nanoparticles in endothelial cells were measured by quantitative real time polymerase chain reaction. PEGylated-gold nanoparticles were stable under physiological conditions and PEGylated-gold nanoparticles-5400 and PEGylated-gold nanoparticles-10800 did not affect platelet aggregation as measured by Quartz Crystal Microbalance with Dissipation. In addition, PEGylated-gold nanoparticles did not induce an inflammatory response when incubated with endothelial cells. Therefore, this study shows that PEGylated-gold nanoparticles with a higher molecular weight of the polymer chain are both platelet- and endothelium-compatible making them attractive candidates for biomedical applications. PMID:24749395

  7. Method for producing metallic nanoparticles

    DOEpatents

    Phillips, Jonathan; Perry, William L.; Kroenke, William J.

    2004-02-10

    Method for producing metallic nanoparticles. The method includes generating an aerosol of solid metallic microparticles, generating non-oxidizing plasma with a plasma hot zone at a temperature sufficiently high to vaporize the microparticles into metal vapor, and directing the aerosol into the hot zone of the plasma. The microparticles vaporize in the hot zone to metal vapor. The metal vapor is directed away from the hot zone and to the plasma afterglow where it cools and condenses to form solid metallic nanoparticles.

  8. Multiscaffold DNA Origami Nanoparticle Waveguides

    PubMed Central

    2013-01-01

    DNA origami templated self-assembly has shown its potential in creating rationally designed nanophotonic devices in a parallel and repeatable manner. In this investigation, we employ a multiscaffold DNA origami approach to fabricate linear waveguides of 10 nm diameter gold nanoparticles. This approach provides independent control over nanoparticle separation and spatial arrangement. The waveguides were characterized using atomic force microscopy and far-field polarization spectroscopy. This work provides a path toward large-scale plasmonic circuitry. PMID:23841957

  9. Functionalized magnetic nanoparticle analyte sensor

    DOEpatents

    Yantasee, Wassana; Warner, Maryin G; Warner, Cynthia L; Addleman, Raymond S; Fryxell, Glen E; Timchalk, Charles; Toloczko, Mychailo B

    2014-03-25

    A method and system for simply and efficiently determining quantities of a preselected material in a particular solution by the placement of at least one superparamagnetic nanoparticle having a specified functionalized organic material connected thereto into a particular sample solution, wherein preselected analytes attach to the functionalized organic groups, these superparamagnetic nanoparticles are then collected at a collection site and analyzed for the presence of a particular analyte.

  10. Defined DNA/nanoparticle conjugates.

    PubMed

    Ackerson, Christopher J; Sykes, Michael T; Kornberg, Roger D

    2005-09-20

    Glutathione monolayer-protected gold clusters were reacted by place exchange with 19- or 20-residue thiolated oligonucleotides. The resulting DNA/nanoparticle conjugates could be separated on the basis of the number of bound oligonucleotides by gel electrophoresis and assembled with one another by DNA-DNA hybridization. This approach overcomes previous limitations of DNA/nanoparticle synthesis and yields conjugates that are precisely defined with respect to both gold and nucleic acid content. PMID:16155122

  11. STED microscopy resolves nanoparticle assemblies

    NASA Astrophysics Data System (ADS)

    Willig, K. I.; Keller, J.; Bossi, M.; Hell, S. W.

    2006-06-01

    We demonstrate the ability of stimulated emission depletion (STED) microscopy, a far-field fluorescence imaging technique with diffraction-unlimited resolution, to reveal the spatial order of fluorescent nanoparticles. Unlike its confocal counterpart, here STED microscopy resolves the arrangements of densely packed 40 nm beads, supramolecular aggregates in a cell membrane, and colloidal nanoparticles. Both raw and linearly deconvolved data disclose unprecedented details of both biological and non-biological nanopatterns.

  12. Diamond Synthesis Employing Nanoparticle Seeds

    NASA Technical Reports Server (NTRS)

    Uppireddi, Kishore (Inventor); Morell, Gerardo (Inventor); Weiner, Brad R. (Inventor)

    2014-01-01

    Iron nanoparticles were employed to induce the synthesis of diamond on molybdenum, silicon, and quartz substrates. Diamond films were grown using conventional conditions for diamond synthesis by hot filament chemical vapor deposition, except that dispersed iron oxide nanoparticles replaced the seeding. This approach to diamond induction can be combined with dip pen nanolithography for the selective deposition of diamond and diamond patterning while avoiding surface damage associated to diamond-seeding methods.

  13. Polyelemental nanoparticle libraries.

    PubMed

    Chen, Peng-Cheng; Liu, Xiaolong; Hedrick, James L; Xie, Zhuang; Wang, Shunzhi; Lin, Qing-Yuan; Hersam, Mark C; Dravid, Vinayak P; Mirkin, Chad A

    2016-06-24

    Multimetallic nanoparticles are useful in many fields, yet there are no effective strategies for synthesizing libraries of such structures, in which architectures can be explored in a systematic and site-specific manner. The absence of these capabilities precludes the possibility of comprehensively exploring such systems. We present systematic studies of individual polyelemental particle systems, in which composition and size can be independently controlled and structure formation (alloy versus phase-separated state) can be understood. We made libraries consisting of every combination of five metallic elements (Au, Ag, Co, Cu, and Ni) through polymer nanoreactor-mediated synthesis. Important insight into the factors that lead to alloy formation and phase segregation at the nanoscale were obtained, and routes to libraries of nanostructures that cannot be made by conventional methods were developed. PMID:27339985

  14. Nanoparticles and Neurotoxicity

    PubMed Central

    Win-Shwe, Tin-Tin; Fujimaki, Hidekazu

    2011-01-01

    Humans are exposed to nanoparticles (NPs; diameter < 100 nm) from ambient air and certain workplaces. There are two main types of NPs; combustion-derived NPs (e.g., particulate matters, diesel exhaust particles, welding fumes) and manufactured or engineered NPs (e.g., titanium dioxide, carbon black, carbon nanotubes, silver, zinc oxide, copper oxide). Recently, there have been increasing reports indicating that inhaled NPs can reach the brain and may be associated with neurodegeneration. It is necessary to evaluate the potential toxic effects of NPs on brain because most of the neurobehavioral disorders may be of environmental origin. This review highlights studies on both combustion-derived NP- and manufactured or engineered NP-induced neuroinflammation, oxidative stress, and gene expression, as well as the possible mechanism of these effects in animal models and in humans. PMID:22016657

  15. TOPICAL REVIEW: Nanoparticle catalysts

    NASA Astrophysics Data System (ADS)

    Moshfegh, A. Z.

    2009-12-01

    In this review, the importance of nanoparticles (NPs), with emphasis on their general and specific properties, especially the high surface-to-volume ratio (A/V), in many technological and industrial applications is studied. Some physical and chemical preparation methods for growing several metallic and binary alloy NP catalysts are reviewed. The growth and mechanism of catalytic reactions for synthesis of 1D nanostructures such as ZnO nanowires and multiwall carbon nanotubes (MWCNTs) are discussed. Gas-phase production with emphasis on dependence of catalytic activity and selectivity on size, shape and structure of NPs is also investigated. Application of NP catalysts in several technological processes including H2 production and storage as well as antibacterial effect, gas sensors and fuel cells is discussed. The mechanism of H2 production from catalytic photoelectrochemical and photocatalytic degradation reactions of some organic dyes is discussed. Finally, the future outlook of NP catalysts in various disciplines is presented.

  16. Nitric Oxide Nanoparticle Technology

    PubMed Central

    Englander, Laura

    2010-01-01

    Staphylococcus aureus infections account for the majority of skin and soft tissue infections in the United States. Staphylococcus aureus is rapidly evolving resistance to contemporary topical as well as systemic antibiotics. Alternatives to current treatment options for skin and soft tissue infections are needed for more effective treatment now and in the future. Nitric oxide's proven roles in both wound repair and as an antimicrobial agent make it an excellent candidate for the treatment of skin infections. Recent attempts at novel nitric oxide therapies, in the form of nitric oxide donors, have shown limited potential in treating cutaneous infection. However, more recent developments in nitric oxide delivery, using nitric oxide nanoparticle technology, demonstrate substantial promise in the promotion of wound repair and eradication of skin and soft tissue infections. PMID:20725551

  17. Nanoparticles and neurotoxicity.

    PubMed

    Win-Shwe, Tin-Tin; Fujimaki, Hidekazu

    2011-01-01

    Humans are exposed to nanoparticles (NPs; diameter < 100 nm) from ambient air and certain workplaces. There are two main types of NPs; combustion-derived NPs (e.g., particulate matters, diesel exhaust particles, welding fumes) and manufactured or engineered NPs (e.g., titanium dioxide, carbon black, carbon nanotubes, silver, zinc oxide, copper oxide). Recently, there have been increasing reports indicating that inhaled NPs can reach the brain and may be associated with neurodegeneration. It is necessary to evaluate the potential toxic effects of NPs on brain because most of the neurobehavioral disorders may be of environmental origin. This review highlights studies on both combustion-derived NP- and manufactured or engineered NP-induced neuroinflammation, oxidative stress, and gene expression, as well as the possible mechanism of these effects in animal models and in humans. PMID:22016657

  18. Polyelemental nanoparticle libraries

    NASA Astrophysics Data System (ADS)

    Chen, Peng-Cheng; Liu, Xiaolong; Hedrick, James L.; Xie, Zhuang; Wang, Shunzhi; Lin, Qing-Yuan; Hersam, Mark C.; Dravid, Vinayak P.; Mirkin, Chad A.

    2016-06-01

    Multimetallic nanoparticles are useful in many fields, yet there are no effective strategies for synthesizing libraries of such structures, in which architectures can be explored in a systematic and site-specific manner. The absence of these capabilities precludes the possibility of comprehensively exploring such systems. We present systematic studies of individual polyelemental particle systems, in which composition and size can be independently controlled and structure formation (alloy versus phase-separated state) can be understood. We made libraries consisting of every combination of five metallic elements (Au, Ag, Co, Cu, and Ni) through polymer nanoreactor–mediated synthesis. Important insight into the factors that lead to alloy formation and phase segregation at the nanoscale were obtained, and routes to libraries of nanostructures that cannot be made by conventional methods were developed.

  19. Nanoparticles Containing Insoluble Drug for Cancer Therapy

    PubMed Central

    Guo, Shutao; Huang, Leaf

    2014-01-01

    Nanoparticle drug formulations have been extensively researched and developed in the field of drug delivery as a means to efficiently deliver insoluble drugs to tumor cells. By mechanisms of the enhanced permeability and retention effect, nanoparticle drug formulations are capable of greatly enhancing the safety, pharmacokinetic profiles and bioavailability of the administered treatment. Here, the progress of various nanoparticle formulations in both research and clinical applications is detailed with a focus on the development of drug/gene delivery systems. Specifically, the unique advantages and disadvanges of polymeric nanoparticles, liposomes, solid lipid nanoparticles, nanocrystals and lipid-coated nanoparticles for targeted drug delivery will be investigated in detail. PMID:24113214

  20. Biomedical applications of gold nanoparticles.

    PubMed

    Cabuzu, Daniela; Cirja, Andreea; Puiu, Rebecca; Grumezescu, Alexandru Mihai

    2015-01-01

    Gold nanoparticles may be used in different domains, one of most important being the biomedical field. They have suitable properties for controlled drug delivery, cancer treatment, biomedical imaging, diagnosis and many others, due to their excellent compatibility with the human organism, low toxicity and tunable stability, small dimensions, and possibility to interact with a variety of substances. They also have optical properties, being able to absorb infrared light. Moreover, due to their large surface and the ability of being coated with a variety of therapeutic agents, gold nanoparticles have been showed a great potential to be used as drug delivery systems. Gold nanoparticles are intensively studied in biomedicine, and recent studies revealed the fact that they can cross the blood-brain barrier, may interact with the DNA and produce genotoxic effects. Because of their ability of producing heat, they can target and kill the tumors, being used very often in photodynamic therapy. Gold nanoparticles can be synthesized in many ways, but the most common are the biological and chemical methods, however the chemical method offers the advantage of better controlling the size and shape of the nanoparticles. In this review, we present the principal applications of gold nanoparticles in the biomedical field, like cancer treatment, amyloid-like fibrillogenesis inhibitors, transplacental treatment, the development of specific scaffolds and drug delivery systems. PMID:25877087

  1. [Nanoparticles: properties and application prospects].

    PubMed

    Chekman, I S

    2009-01-01

    A new trend of scientific-technical and medical researches has been formed which unites nanoscience, nanotechnology, nanomedicine, nanopharmacology. Nanoparticles are the main product of nanotechnologies. Nanoparticles are organic and inorganic structures, their size being less than one hundred nanometers (nano from Greece nanos--a dwarf; particle is a separate unit which is separated from the whole). Prefix nano means 10(-9) m. Nanosizes are values from 1 to 100 nanometers, micro-sizes--from 100 to 1000 nanometers, and above 1000 nanometers--are macrosizes. By the data of Internet for 1.08.20.2008 there are 18512 papers in the world scientific literature (8663 of them were published during the last 2.5 years), where properties of nanoparticles which are obtained by different nanotechnological methods are described. Actually, quantity of works concerning nanoparticles is much more because not all publications are cited in Internet. The first publication concerning a characteristic of nanoparticles was published in 1978. The survey generalized the data of scientific literature and author's investigations which concern sizes of nanoparticles of biologic molecules and their properties. PMID:19877425

  2. Gold nanoparticles enhancing protontherapy efficiency.

    PubMed

    Torrisi, Lorenzo

    2015-01-01

    The insertion of gold nanoparticles in biological liquids, tissues and organs permits to increase the equivalent atomic number of the medium that, if used as target to be irradiated by ionizing radiation, permits an increment of the absorbed dose. No toxic nanoparticles, such as the Au, can be injected in the cancer tissues at different concentrations before using a localized treatment that uses energetic proton beams for radiotherapy. Due to the high density and atomic number of the used gold nanoparticles, the absorbed radiation dose can be increased to about a factor six per cent using relatively low concentration of nanoparticles injectable as solution in the tumor tissue. This means to reduce the exposition to ionizing radiation or to increase the dose to the tumor site. Simulation programs of proton energy loss in tissues, using SRIM Code, are employed to evaluate the Bragg peak enhancing in presence of Au nanoparticles, so it will be presented and discussed. Some research findings and patents in the gold nanoparticle preparation and application to Medicine are reviewed in the present paper. PMID:25986229

  3. Celecoxib Nanoparticles for Therapeutic Angiogenesis.

    PubMed

    Margulis, Katherine; Neofytou, Evgenios A; Beygui, Ramin E; Zare, Richard N

    2015-09-22

    Controllable induction of blood vessel formation (angiogenesis) presents an important therapeutic goal in ischemic diseases and is also beneficial in various normal physiological processes. In this study, we have shown that nanoparticles of celecoxib, a lipophilic nonsteroidal anti-inflammatory drug, effectively evoke therapeutic angiogenesis in animal models, in both normal and ischemic organs. Celecoxib is widely considered to inhibit angiogenesis, although a recent study suggests that it can instead promote blood vessel growth in cancer cell lines. The hydrophobic nature of this drug necessitates its administration in nanoparticulate form in order to elicit a perceivable pharmacological response. We developed a facile method for nanoparticle formation by solvent extraction from microemulsions in supercritical carbon dioxide. This method exploits a spontaneous formation of nanometric domains within the microemulsion system and their rapid conversion to nanoparticles by supercritical fluid. The resultant nanoparticles were administered subcutaneously to mice in a biocompatible hydrogel, and caused a 4-fold increase in blood vessel count in normally perfused skin compared with drug-free particles. They were at least as effective in inducing angiogenesis as nanoparticles of deferoxamine, a well-established neovascularization promoter. Next, we evaluated their effect on ischemic tissues in murine model of myocardial infarction. We found that celecoxib nanoparticles were able to induce a significant vascularization of ischemic myocardium and hamper the progression of heart failure, which points toward a new approach for treating ischemia. PMID:26244654

  4. Interfacial functionalization and engineering of nanoparticles

    NASA Astrophysics Data System (ADS)

    Song, Yang

    The intense research interest in nanoscience and nanotechnology is largely fueled by the unique properties of nanoscale materials. In this dissertation, the research efforts are focused on surface functionalization and interfacial engineering of functional nanoparticles in the preparation of patchy nanoparticles (e.g., Janus nanoparticles and Neapolitan nanoparticles) such that the nanoparticle structures and properties may be manipulated to an unprecedented level of sophistication. Experimentally, Janus nanoparticles were prepared by an interfacial engineering method where one hemisphere of the originally hydrophobic nanoparticles was replaced with hydrophilic ligands at the air|liquid or solid|liquid interface. The amphiphilic surface characters of the Janus nanoparticles were verified by contact angle measurements, as compared to those of the bulk-exchange counterparts where the two types of ligands were distributed rather homogeneously on the nanoparticle surface. In a further study, a mercapto derivative of diacetylene was used as the hydrophilic ligands to prepare Janus nanoparticles by using hydrophobic hexanethiolate-protected gold nanoparticles as the starting materials. Exposure to UV irradiation led to effective covalent cross-linking between the diacetylene moieties of neighboring ligands and hence marked enhancement of the structural integrity of the Janus nanoparticles, which was attributable to the impeded surface diffusion of the thiol ligands on the nanoparticle surface, as manifested in fluorescence measurements of aged nanoparticles. More complicated bimetallic AgAu Janus nanoparticles were prepared by interfacial galvanic exchange reactions of a Langmuir-Blodgett monolayer of 1-hexanethiolate-passivated silver nanoparticles on a glass slide with gold(I)-mercaptopropanediol complex in a water/ethanol solution. The resulting nanoparticles exhibited an asymmetrical distribution not only of the organic capping ligands on the nanoparticle surface but

  5. Magnetic Nanoparticles for Biomedical Applications

    NASA Astrophysics Data System (ADS)

    Jing, Ying

    Nanotechnology is revolutionizing human's life. Synthesis and application of magnetic nanoparticles is a fast burgeoning field which has potential to bring significant advance in many fields, for example diagnosis and treatment in biomedical area. Novel nanoparticles to function efficiently and intelligently are in desire to improve the current technology. We used a magnetron-sputtering-based nanocluster deposition technique to synthesize magnetic nanoparticles in gas phase, and specifically engineered nanoparticles for different applications. Alternating magnetic field heating is emerging as a technique to assist cancer treatment or drug delivery. We proposed high-magnetic-moment Fe3Si particles with relatively large magnetic anisotropy energy should in principle provide superior performance. Such nanoparticles were experimentally synthesized and characterized. Their promising magnetic properties can contribute to heating performance under suitable alternating magnetic field conditions. When thermal energy is used for medical treatment, it is ideal to work in a designed temperature range. Biocompatible and "smart" magnetic nanoparticles with temperature self-regulation were designed from both materials science and biomedicine aspects. We chose Fe-Si material system to demonstrate the concept. Temperature dependent physical property was adjusted by tuning of exchange coupling between Fe atoms through incorporation of various amount of Si. The magnetic moment can still be kept in a promising range. The two elements are both biocompatible, which is favored by in-vivo medical applications. A combination of "smart" magnetic particles and thermo-sensitive polymer were demonstrated to potentially function as a platform for drug delivery. Highly sensitive diagnosis for point-of-care is in desire nowadays. We developed composition- and phase-controlled Fe-Co nanoparticles for bio-molecule detection. It has been demonstrated that Fe70Co30 nanoparticles and giant

  6. Development of polymeric–cationic peptide composite nanoparticles, a nanoparticle-in-nanoparticle system for controlled gene delivery

    PubMed Central

    Jain, Arvind K; Massey, Ashley; Yusuf, Helmy; McDonald, Denise M; McCarthy, Helen O; Kett, Vicky L

    2015-01-01

    We report the formulation of novel composite nanoparticles that combine the high transfection efficiency of cationic peptide-DNA nanoparticles with the biocompatibility and prolonged delivery of polylactic acid–polyethylene glycol (PLA-PEG). The cationic cell-penetrating peptide RALA was used to condense DNA into nanoparticles that were encapsulated within a range of PLA-PEG copolymers. The composite nanoparticles produced exhibited excellent physicochemical properties including size <200 nm and encapsulation efficiency >80%. Images of the composite nanoparticles obtained with a new transmission electron microscopy staining method revealed the peptide-DNA nanoparticles within the PLA-PEG matrix. Varying the copolymers modulated the DNA release rate >6 weeks in vitro. The best formulation was selected and was able to transfect cells while maintaining viability. The effect of transferrin-appended composite nanoparticles was also studied. Thus, we have demonstrated the manufacture of composite nanoparticles for the controlled delivery of DNA. PMID:26648722

  7. Molecular Imaging with Theranostic Nanoparticles

    PubMed Central

    Jokerst, Jesse V.; Gambhir, Sanjiv S.

    2011-01-01

    Conspectus Nanoparticles offer diagnostic and therapeutic capabilities impossible with small molecules or micro-scale tools. As molecular biology merges with medical imaging to form the field of molecular imaging, nanoparticle imaging is increasingly common with both therapeutic and diagnostic applications. The term theranostic indicates technology with concurrent and complementary diagnostic and therapeutic capabilities. When performed with sub-micron materials, the field may be termed theranostic nanomedicine. Although nanoparticles have been FDA-approved for clinical use as transport vehicles for nearly 15 years, full translation of their theranostic potential is incomplete. Still, remarkable successes with nanoparticles have been realized in the areas of drug delivery and magnetic resonance imaging. Emerging applications include image-guided resection, optical/photoacoustic imaging in vivo, contrast-enhanced ultrasound, and thermoablative therapy. Diagnosis with nanoparticles in molecular imaging involves correlating signal to a phenotype. The disease’s size, stage, and biochemical signature can be gleaned from the location and intensity of nanoparticle signal emanating from a living subject. Therapy with NP uses the image for resection or delivery of small molecule or RNA thererapeutic. Ablation of the affected area is also possible via heat or radioactivity. The ideal theranostic NP: (1) selectively and rapidly accumulates in diseased tissue, (2) reports biochemical and morphological characteristics of the area, (3) delivers a non-invasive therapeutic, and (4) is safe and biodegrades with non-toxic byproducts. Above is a schematic of such a system which contains a central imaging core (yellow) surrounded by small molecule therapeutics (red). The system targets via ligands such as IgG (pink) and is protected from immune scavengers by a cloak of protective polymer (green). While no nanoparticle has achieved all of the above features, many NPs do fulfill one

  8. Ultrasound mediated nanoparticle drug delivery

    NASA Astrophysics Data System (ADS)

    Mullin, Lee B.

    Ultrasound is not only a powerful diagnostic tool, but also a promising therapeutic technology that can be used to improve localized drug delivery. Microbubble contrast agents are micron sized encapsulated gas filled bubbles that are administered intravenously. Originally developed to enhance ultrasound images, microbubbles are highly echogenic due to the gas core that provides a detectable impedance difference from the surrounding medium. The core also allows for controlled response of the microbubbles to ultrasound pulses. Microbubbles can be pushed using acoustic radiation force and ruptured using high pressures. Destruction of microbubbles can increase permeability at the cellular and vascular level, which can be advantageous for drug delivery. Advances in drug delivery methods have been seen with the introduction of nanoparticles, nanometer sized objects often carrying a drug payload. In chemotherapy, nanoparticles can deliver drugs to tumors while limiting systemic exposure due to abnormalities in tumor vasculature such large gaps between endothelial cells that allow nanoparticles to enter into the interstitial space; this is referred to as the enhanced permeability and retention (EPR) effect. However, this effect may be overestimated in many tumors. Additionally, only a small percentage of the injected dose accumulates in the tumor, which most the nanoparticles accumulating in the liver and spleen. It is hypothesized that combining the acoustic activity of an ultrasound contrast agent with the high payload and extravasation ability of a nanoparticle, localized delivery to the tumor with reduced systemic toxicity can be achieved. This method can be accomplished by either loading nanoparticles onto the shell of the microbubble or through a coadministration method of both nanoparticles and microbubbles. The work presented in this dissertation utilizes novel and commercial nanoparticle formulations, combined with microbubbles and a variety of ultrasound systems

  9. Nanoparticle bridge DNA biosensor

    NASA Astrophysics Data System (ADS)

    Huang, Hong-Wen

    A new DNA sensing method is demonstrated in which DNA hybridization events lead to the formation of nanoparticle satellites that bridge two electrodes and are detected electrically. The hybridization events are exclusively carried out only on specific locations, the surfaces of C-ssDNA modified 50 nm GNPs. The uniqueness of this work is that only a small number of T-ccDNA molecules (<10) is required to form the nanoparticle satellites, allowing ultra-sensitive DNA sensing. The principle of this new DNA sensing technique has been demonstrated using target DNA and three-base-pair-mismatched DNA in 20nM concentrations. Three single-stranded DNA (ssDNA) system is used in our experiment which includes Capture-ssDNA (C-ssDNA), Target-ssDNA (T-ssDNA) and Probe-ssDNA (P-ssDNA). Both C-ssDNA and P-ssDNA are modified by a thiol group and can hybridize with different portions of T-ssDNA. T-ssDNA requires no modification in three ssDNA system, which is beneficial in many applications. C-ssDNA modified 50nm gold nanoparticle (C-50au) and P-ssDNA modified 30nm gold nanoparticle (P-30au) are prepared through the reaction of thiol-gold chemical bonding between thiolated ssDNA and gold nanoparticle (GNP) (C-ssDNA with 50nm GNP, P-ssDNA with 30nm GNP). We controllably place the C-50au only on the SiO2 band surface (˜ 90nm width) between two gold electrodes (source and drain electrodes) by forming positively- and negatively-charged self-assembled monolayers (SAMs) on SiO2 and gold surface, respectively. DNA modified GNP is negatively charged due to ionization of phosphate group on DNA back bone. C-50au therefore is negatively charged and can only be attracted toward SiO2 area (repelled by negatively charged gold electrode surface). The amine group of positively-charged SAMs on SiO2 surface is then passivated by converting to non-polar methyl functional group after C-50au placement. P-30au is first hybridized with T-ssDNA in the solution phase (T-P- 30au formed) and is introduced

  10. Mycosynthesis of silver nanoparticles bearing antibacterial activity.

    PubMed

    Azmath, Pasha; Baker, Syed; Rakshith, Devaraju; Satish, Sreedharamurthy

    2016-03-01

    Mycosynthesis of silver nanoparticles was achieved by endophytic Colletotrichum sp. ALF2-6 inhabiting Andrographis paniculata. Well dispersed nanoparticles were characterized using UV-Visible spectrometry with maximum absorption conferring at 420 nm. FTIR analysis revealed possible biomolecules reducing the metal salt and stabilization of nanoparticles. XRD analysis depicted the diffraction intensities exhibiting between 20 and 80 °C at 2theta angle thus conferring the crystalline nature of nanoparticles. Morphological characteristic using TEM revealed the polydispersity of nanoparticles with size ranging from 20 to 50 nm. Synthesized nanoparticles exhibited bactericidal activity against selected human pathogens. Nanoparticles mode of action was carried out to reveal DNA damage activity. Thus the present investigation reports facile fabrication of silver nanoparticles from endophytic fungi. PMID:27013906

  11. Mycosynthesis of silver nanoparticles bearing antibacterial activity

    PubMed Central

    Azmath, Pasha; Baker, Syed; Rakshith, Devaraju; Satish, Sreedharamurthy

    2015-01-01

    Mycosynthesis of silver nanoparticles was achieved by endophytic Colletotrichum sp. ALF2-6 inhabiting Andrographis paniculata. Well dispersed nanoparticles were characterized using UV–Visible spectrometry with maximum absorption conferring at 420 nm. FTIR analysis revealed possible biomolecules reducing the metal salt and stabilization of nanoparticles. XRD analysis depicted the diffraction intensities exhibiting between 20 and 80 °C at 2theta angle thus conferring the crystalline nature of nanoparticles. Morphological characteristic using TEM revealed the polydispersity of nanoparticles with size ranging from 20 to 50 nm. Synthesized nanoparticles exhibited bactericidal activity against selected human pathogens. Nanoparticles mode of action was carried out to reveal DNA damage activity. Thus the present investigation reports facile fabrication of silver nanoparticles from endophytic fungi. PMID:27013906

  12. Synthesis and Characterization of Environmentally Benign Nanoparticles

    EPA Science Inventory

    There has been a growing interest in replacing current non-biodegradable and toxic nanosystems with environmentally benign biopolymer based ones to minimize post-utilization hazards due to uncontrolled accumulation of nanoparticles in the environment. Lignin based nanoparticles (...

  13. Endotoxin hitchhiking on polymer nanoparticles.

    PubMed

    Donnell, Mason L; Lyon, Andrew J; Mormile, Melanie R; Barua, Sutapa

    2016-07-15

    The control of microbial infections is critical for the preparation of biological media including water to prevent lethal septic shock. Sepsis is one of the leading causes of death in the United States. More than half a million patients suffer from sepsis every year. Both gram-positive and gram-negative bacteria are responsible for septic infection by the most common organisms i.e., Escherichia coli and Pseuodomonas aeruginosa. The bacterial cell membrane releases negatively charged endotoxins upon death and enzymatic destruction, which stimulate antigenic response in humans to gram-negative infections. Several methods including distillation, ethylene oxide treatment, filtration and irradiation have been employed to remove endotoxins from contaminated samples, however, the reduction efficiency remains low, and presents a challenge. Polymer nanoparticles can be used to overcome the current inability to effectively sequester endotoxins from water. This process is termed endotoxin hitchhiking. The binding of endotoxin on polymer nanoparticles via electrostatic and hydrophobic interactions offers efficient removal from water. However, the effect of polymer nanoparticles and its surface areas has not been investigated for removal of endotoxins. Poly(ε-caprolactone) (PCL) polymer was tested for its ability to effectively bind and remove endotoxins from water. By employing a simple one-step phase separation technique, we were able to synthesize PCL nanoparticles of 398.3 ± 95.13 nm size and a polydispersity index of 0.2. PCL nanoparticles showed ∼78.8% endotoxin removal efficiency, the equivalent of 3.9 × 10(5) endotoxin units (EU) per ml. This is 8.34-fold more effective than that reported for commercially available membranes. Transmission electron microscopic images confirmed binding of multiple endotoxins to the nanoparticle surface. The concept of using nanoparticles may be applicable not only to eliminate gram-negative bacteria, but also for any gram

  14. Endotoxin hitchhiking on polymer nanoparticles

    NASA Astrophysics Data System (ADS)

    Donnell, Mason L.; Lyon, Andrew J.; Mormile, Melanie R.; Barua, Sutapa

    2016-07-01

    The control of microbial infections is critical for the preparation of biological media including water to prevent lethal septic shock. Sepsis is one of the leading causes of death in the United States. More than half a million patients suffer from sepsis every year. Both gram-positive and gram-negative bacteria are responsible for septic infection by the most common organisms i.e., Escherichia coli and Pseuodomonas aeruginosa. The bacterial cell membrane releases negatively charged endotoxins upon death and enzymatic destruction, which stimulate antigenic response in humans to gram-negative infections. Several methods including distillation, ethylene oxide treatment, filtration and irradiation have been employed to remove endotoxins from contaminated samples, however, the reduction efficiency remains low, and presents a challenge. Polymer nanoparticles can be used to overcome the current inability to effectively sequester endotoxins from water. This process is termed endotoxin hitchhiking. The binding of endotoxin on polymer nanoparticles via electrostatic and hydrophobic interactions offers efficient removal from water. However, the effect of polymer nanoparticles and its surface areas has not been investigated for removal of endotoxins. Poly(ε-caprolactone) (PCL) polymer was tested for its ability to effectively bind and remove endotoxins from water. By employing a simple one-step phase separation technique, we were able to synthesize PCL nanoparticles of 398.3 ± 95.13 nm size and a polydispersity index of 0.2. PCL nanoparticles showed ∼78.8% endotoxin removal efficiency, the equivalent of 3.9 × 105 endotoxin units (EU) per ml. This is 8.34-fold more effective than that reported for commercially available membranes. Transmission electron microscopic images confirmed binding of multiple endotoxins to the nanoparticle surface. The concept of using nanoparticles may be applicable not only to eliminate gram-negative bacteria, but also for any gram

  15. Dynamic Nanoparticles Assemblies

    PubMed Central

    WANG, LIBING; XU, LIGUANG; KUANG, HUA; XU, CHUANLAI; KOTOV, NICHOLAS A.

    2012-01-01

    CONSPECTUS Importance Although nanoparticle (NP) assemblies are at the beginning of their development, their unique geometrical shapes and media-responsive optical, electronic and magnetic properties have attracted significant interest. Nanoscale assembly bridges multiple sizes of materials: individual nanoparticles, discrete molecule-like or virus-like nanoscale agglomerates, microscale devices, and macroscale materials. The capacity to self-assemble can greatly facilitate the integration of nanotechnology with other technologies and, in particular, with microscale fabrication. In this Account, we describe developments in the emerging field of dynamic NP assemblies, which are spontaneously formed superstructures containing more than two inorganic nanoscale particles that display ability to change their geometrical, physical, chemical, and other attributes. In many ways, dynamic assemblies can represent a bottleneck in the ‘bottom-up’ fabrication of NP-based devices because they can produce a much greater variety of assemblies, but they also provide a convenient tool for variation of geometries and dimensions of nanoparticle assemblies. Classification Superstructures of NPs (and those held together by similar intrinsic forces) are classified into two groups: Class 1 where media and external fields can alter shape, conformation, and order of stable superstructures with a nearly constant number same. The future development of successful dynamic assemblies requires understanding the equilibrium in dynamic NP systems. The dynamic nature of Class 1 assemblies is associated with the equilibrium between different conformations of a superstructure and is comparable to the isomerization in classical chemistry. Class 2 assemblies involve the formation and/or breakage of linkages between the NPs, which is analogous to the classical chemical equilibrium for the formation of a molecule from atoms. Finer classification of NP assemblies in accord with established conventions

  16. Alloy nanoparticle synthesis using ionizing radiation

    DOEpatents

    Nenoff, Tina M.; Powers, Dana A.; Zhang, Zhenyuan

    2011-08-16

    A method of forming stable nanoparticles comprising substantially uniform alloys of metals. A high dose of ionizing radiation is used to generate high concentrations of solvated electrons and optionally radical reducing species that rapidly reduce a mixture of metal ion source species to form alloy nanoparticles. The method can make uniform alloy nanoparticles from normally immiscible metals by overcoming the thermodynamic limitations that would preferentially produce core-shell nanoparticles.

  17. Optical trapping of nanoparticles.

    PubMed

    Bergeron, Jarrah; Zehtabi-Oskuie, Ana; Ghaffari, Saeedeh; Pang, Yuanjie; Gordon, Reuven

    2013-01-01

    Optical trapping is a technique for immobilizing and manipulating small objects in a gentle way using light, and it has been widely applied in trapping and manipulating small biological particles. Ashkin and co-workers first demonstrated optical tweezers using a single focused beam. The single beam trap can be described accurately using the perturbative gradient force formulation in the case of small Rayleigh regime particles. In the perturbative regime, the optical power required for trapping a particle scales as the inverse fourth power of the particle size. High optical powers can damage dielectric particles and cause heating. For instance, trapped latex spheres of 109 nm in diameter were destroyed by a 15 mW beam in 25 sec, which has serious implications for biological matter. A self-induced back-action (SIBA) optical trapping was proposed to trap 50 nm polystyrene spheres in the non-perturbative regime. In a non-perturbative regime, even a small particle with little permittivity contrast to the background can influence significantly the ambient electromagnetic field and induce a large optical force. As a particle enters an illuminated aperture, light transmission increases dramatically because of dielectric loading. If the particle attempts to leave the aperture, decreased transmission causes a change in momentum outwards from the hole and, by Newton's Third Law, results in a force on the particle inwards into the hole, trapping the particle. The light transmission can be monitored; hence, the trap can become a sensor. The SIBA trapping technique can be further improved by using a double-nanohole structure. The double-nanohole structure has been shown to give a strong local field enhancement. Between the two sharp tips of the double-nanohole, a small particle can cause a large change in optical transmission, thereby inducing a large optical force. As a result, smaller nanoparticles can be trapped, such as 12 nm silicate spheres and 3.4 nm hydrodynamic radius

  18. Optical Trapping of Nanoparticles

    PubMed Central

    Bergeron, Jarrah; Zehtabi-Oskuie, Ana; Ghaffari, Saeedeh; Pang, Yuanjie; Gordon, Reuven

    2013-01-01

    Optical trapping is a technique for immobilizing and manipulating small objects in a gentle way using light, and it has been widely applied in trapping and manipulating small biological particles. Ashkin and co-workers first demonstrated optical tweezers using a single focused beam1. The single beam trap can be described accurately using the perturbative gradient force formulation in the case of small Rayleigh regime particles1. In the perturbative regime, the optical power required for trapping a particle scales as the inverse fourth power of the particle size. High optical powers can damage dielectric particles and cause heating. For instance, trapped latex spheres of 109 nm in diameter were destroyed by a 15 mW beam in 25 sec1, which has serious implications for biological matter2,3. A self-induced back-action (SIBA) optical trapping was proposed to trap 50 nm polystyrene spheres in the non-perturbative regime4. In a non-perturbative regime, even a small particle with little permittivity contrast to the background can influence significantly the ambient electromagnetic field and induce a large optical force. As a particle enters an illuminated aperture, light transmission increases dramatically because of dielectric loading. If the particle attempts to leave the aperture, decreased transmission causes a change in momentum outwards from the hole and, by Newton's Third Law, results in a force on the particle inwards into the hole, trapping the particle. The light transmission can be monitored; hence, the trap can become a sensor. The SIBA trapping technique can be further improved by using a double-nanohole structure. The double-nanohole structure has been shown to give a strong local field enhancement5,6. Between the two sharp tips of the double-nanohole, a small particle can cause a large change in optical transmission, thereby inducing a large optical force. As a result, smaller nanoparticles can be trapped, such as 12 nm silicate spheres7 and 3.4 nm

  19. Nanoparticle Superlattice Engineering with DNA

    NASA Astrophysics Data System (ADS)

    Macfarlane, Robert John

    In this thesis, we describe a set of design rules for using programmable oligonucleotide interactions, elements of both thermodynamic and kinetic control, and an understanding of the dominant forces that are responsible for particle assembly to design and deliberately make a wide variety of nanoparticle-based superlattices. Like the rules for ionic solids developed by Linus Pauling, these rules are guidelines for determining relative nanoparticle superlattice stability, rather than rigorous mathematical descriptions. However, unlike Pauling's rules, the set of rules developed herein allow one to not just predict crystal stability, but also to deliberately and independently control the nanoparticle sizes, interparticle spacings, and crystallographic symmetries of a superlattice. In the first chapter of this thesis, a general background is given for using DNA as a tool in programmable materials synthesis. Chapter 2 demonstrates how altering oligonucleotide length and nanoparticle size can be used to control nanoparticle superlattice lattice parameters with nanometer-scale precision. In the third chapter, the kinetics of crystallization are examined, and a method to selectively stabilize kinetic products is presented. The data in chapter 4 prove that it is the overall hydrodynamic radius of a DNA-functionalized particle, rather than the sizes of the inorganic nanoparticles being assembled, that dictates particle packing behavior. Chapter 5 demonstrates how particles that exhibit non-equivalent packing behavior can be used to control superlattice symmetry, and chapter 6 utilizes these data to develop a phase diagram that predicts lattice stability a priori to synthesis. In chapter 7, the ability to functionalize a particle with multiple types of oligonucleotides is used to synthesize complex lattices, including ternary superlattices that are capable of dynamic symmetry conversion between a binary and a ternary state. The final chapter provides an outlook on other

  20. Lactobacillus assisted synthesis of titanium nanoparticles

    NASA Astrophysics Data System (ADS)

    Prasad, K.; Jha, Anal K.; Kulkarni, A. R.

    2007-05-01

    An eco-friendly lactobacillus sp. (microbe) assisted synthesis of titanium nanoparticles is reported. The synthesis is performed at room temperature. X-ray and transmission electron microscopy analyses are performed to ascertain the formation of Ti nanoparticles. Individual nanoparticles as well as a number of aggregates almost spherical in shape having a size of 40 60 nm are found.

  1. Tannin biosynthesis of iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Herrera-Becerra, R.; Rius, J. L.; Zorrilla, C.

    2010-08-01

    In this work, iron oxide nanoparticles synthesized with gallic acid and tannic acid are characterized using High-Resolution Transmission Electron Microscopy (HRTEM). Its size, form, and structure are compared with nanoparticles obtained previously using alfalfa biomass in order to find a simpler, consistent, and environmentally friendly method in the production of iron oxide nanoparticles.

  2. Nanoparticles for Imaging: Top or Flop?

    PubMed Central

    Mertens, Marianne E.; Grimm, Jan; Lammers, Twan

    2014-01-01

    Nanoparticles are frequently suggested as diagnostic agents. However, except for iron oxide nanoparticles, diagnostic nanoparticles have been barely incorporated into clinical use so far. This is predominantly due to difficulties in achieving acceptable pharmacokinetic properties and reproducible particle uniformity as well as to concerns about toxicity, biodegradation, and elimination. Reasonable indications for the clinical utilization of nanoparticles should consider their biologic behavior. For example, many nanoparticles are taken up by macrophages and accumulate in macrophage-rich tissues. Thus, they can be used to provide contrast in liver, spleen, lymph nodes, and inflammatory lesions (eg, atherosclerotic plaques). Furthermore, cells can be efficiently labeled with nanoparticles, enabling the localization of implanted (stem) cells and tissue-engineered grafts as well as in vivo migration studies of cells. The potential of using nanoparticles for molecular imaging is compromised because their pharmacokinetic properties are difficult to control. Ideal targets for nanoparticles are localized on the endothelial luminal surface, whereas targeted nanoparticle delivery to extravascular structures is often limited and difficult to separate from an underlying enhanced permeability and retention (EPR) effect. The majority of clinically used nanoparticle-based drug delivery systems are based on the EPR effect, and, for their more personalized use, imaging markers can be incorporated to monitor biodistribution, target site accumulation, drug release, and treatment efficacy. In conclusion, although nanoparticles are not always the right choice for molecular imaging (because smaller or larger molecules might provide more specific information), there are other diagnostic and theranostic applications for which nanoparticles hold substantial clinical potential. PMID:25247562

  3. Timed-release polymer nanoparticles.

    PubMed

    Tran, Nguyen T D; Truong, Nghia P; Gu, Wenyi; Jia, Zhongfan; Cooper, Matthew A; Monteiro, Michael J

    2013-02-11

    Triggered-release of encapsulated therapeutics from nanoparticles without remote or environmental triggers was demonstrated in this work. Disassembly of the polymer nanoparticles to unimers at precise times allowed the controlled release of oligo DNA. The polymers used in this study consisted of a hydrophilic block for stabilization and second thermoresponsive block for self-assembly and disassembly. At temperatures below the second block's LCST (i.e., below 37 °C for in vitro assays), the diblock copolymer was fully water-soluble, and when heated to 37 °C, the polymer self-assembled into a narrow size distribution of nanoparticles with an average diameter of approximately 25 nm. The thermoresponsive nature of the second block could be manipulated in situ by the self-catalyzed degradation of cationic 2-(dimethylamino)ethyl acrylate (DMAEA) units to negatively charged acrylic acid groups and when the amount of acid groups was sufficiently high to increase the LCST of the second block above 37 °C. The disassembly of the nanoparticles could be controlled from 10 to 70 h. The use of these nanoparticles as a combined therapy, in which one or more agents can be released in a predetermined way, has the potential to improve the personal point of care treatment of patients. PMID:23298322

  4. Oxidation investigation of nickel nanoparticles.

    PubMed

    Song, Pengxiang; Wen, Dongsheng; Guo, Z X; Korakianitis, Theodosios

    2008-09-01

    This work reported an experimental investigation of complete oxidation of nickel nanoparticles using simultaneous thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC). Nickel nanoparticles and their elemental compositions were characterized by Brunauer-Emmett-Teller (BET) analysis, transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). The oxidation experiments were performed under isoconversion conditions for seven heating rates, varying from 2 to 20 K min(-1), with temperatures up to 1000 degrees C. The experiments revealed unique oxidation behaviour of nickel at the nanometre scale, such as early oxidation and melting phenomena, variable activation energies and different oxidation kinetics between low and high conversion ratios. Unlike its bulk counterpart where the activation energy is a constant, the activation energy of nickel nanoparticles depended on the conversion ratio, ranging between 1.4 and 1.8 eV. The oxidation kinetics of nickel nanoparticles changed from the classical diffusion controlled mechanism to a pseudo-homogeneous reaction as conversion ratios were over 50%. The oxidation mechanisms of nickel nanoparticles were further discussed and future studies to enhance understanding were identified. PMID:18701953

  5. Magnetic nanoparticles for "smart liposomes".

    PubMed

    Nakayama, Yoshitaka; Mustapić, Mislav; Ebrahimian, Haleh; Wagner, Pawel; Kim, Jung Ho; Hossain, Md Shahriar Al; Horvat, Joseph; Martinac, Boris

    2015-12-01

    Liposomal drug delivery systems (LDDSs) are promising tools used for the treatment of diseases where highly toxic pharmacological agents are administered. Currently, destabilising LDDSs by a specific stimulus at a target site remains a major challenge. The bacterial mechanosensitive channel of large conductance (MscL) presents an excellent candidate biomolecule that could be employed as a remotely controlled pore-forming nanovalve for triggered drug release from LDDSs. In this study, we developed superparamagnetic nanoparticles for activation of the MscL nanovalves by magnetic field. Synthesised CoFe2O4 nanoparticles with the radius less than 10 nm were labelled by SH groups for attachment to MscL. Activation of MscL by magnetic field with the nanoparticles attached was examined by the patch clamp technique showing that the number of activated channels under ramp pressure increased upon application of the magnetic field. In addition, we have not observed any cytotoxicity of the nanoparticles in human cultured cells. Our study suggests the possibility of using magnetic nanoparticles as a specific trigger for activation of MscL nanovalves for drug release in LDDSs. PMID:26184724

  6. Ecotoxicity of Nanoparticles

    PubMed Central

    Rana, Sachindri; Kalaichelvan, P. T.

    2013-01-01

    Nanotechnology is a science of producing and utilizing nanosized particles that are measured in nanometers. The unique size-dependent properties make the nanoparticles superior and indispensable as they show unusual physical, chemical, and properties such as conductivity, heat transfer, melting temperature, optical properties, and magnetization. Taking the advantages of these singular properties in order to develop new products is the main purpose of nanotechnology, and that is why it is regarded as “the next industrial revolution.” Although nanotechnology is quite a recent discipline, there have already high number of publications which discuss this topic. However, the safety of nanomaterials is of high priority. Whereas toxicity focuses on human beings and aims at protecting individuals, ecotoxicity looks at various trophic organism levels and intend to protect populations and ecosystems. Ecotoxicity includes natural uptake mechanisms and the influence of environmental factors on bioavailability (and thereby on toxicity). The present paper focuses on the ecotoxic effects and mechanisms of nanomaterials on microorganisms, plants, and other organisms including humans. PMID:23724300

  7. Vaccine delivery using nanoparticles

    PubMed Central

    Gregory, Anthony E.; Titball, Richard; Williamson, Diane

    2013-01-01

    Vaccination has had a major impact on the control of infectious diseases. However, there are still many infectious diseases for which the development of an effective vaccine has been elusive. In many cases the failure to devise vaccines is a consequence of the inability of vaccine candidates to evoke appropriate immune responses. This is especially true where cellular immunity is required for protective immunity and this problem is compounded by the move toward devising sub-unit vaccines. Over the past decade nanoscale size (<1000 nm) materials such as virus-like particles, liposomes, ISCOMs, polymeric, and non-degradable nanospheres have received attention as potential delivery vehicles for vaccine antigens which can both stabilize vaccine antigens and act as adjuvants. Importantly, some of these nanoparticles (NPs) are able to enter antigen-presenting cells by different pathways, thereby modulating the immune response to the antigen. This may be critical for the induction of protective Th1-type immune responses to intracellular pathogens. Their properties also make them suitable for the delivery of antigens at mucosal surfaces and for intradermal administration. In this review we compare the utilities of different NP systems for the delivery of sub-unit vaccines and evaluate the potential of these delivery systems for the development of new vaccines against a range of pathogens. PMID:23532930

  8. Nonadditivity of nanoparticle interactions.

    PubMed

    Batista, Carlos A Silvera; Larson, Ronald G; Kotov, Nicholas A

    2015-10-01

    Understanding interactions between inorganic nanoparticles (NPs) is central to comprehension of self-organization processes and a wide spectrum of physical, chemical, and biological phenomena. However, quantitative description of the interparticle forces is complicated by many obstacles that are not present, or not as severe, for microsize particles (μPs). Here we analyze the sources of these difficulties and chart a course for future research. Such difficulties can be traced to the increased importance of discreteness and fluctuations around NPs (relative to μPs) and to multiscale collective effects. Although these problems can be partially overcome by modifying classical theories for colloidal interactions, such an approach fails to manage the nonadditivity of electrostatic, van der Waals, hydrophobic, and other interactions at the nanoscale. Several heuristic rules identified here can be helpful for discriminating between additive and nonadditive nanoscale systems. Further work on NP interactions would benefit from embracing NPs as strongly correlated reconfigurable systems with diverse physical elements and multiscale coupling processes, which will require new experimental and theoretical tools. Meanwhile, the similarity between the size of medium constituents and NPs makes atomic simulations of their interactions increasingly practical. Evolving experimental tools can stimulate improvement of existing force fields. New scientific opportunities for a better understanding of the electronic origin of classical interactions are converging at the scale of NPs. PMID:26450215

  9. Hyperbolic polaritons in nanoparticles

    NASA Astrophysics Data System (ADS)

    Sun, Zhiyuan; Rubio, Angel; Guinea, Francisco; Basov, Dimitri; Fogler, Michael

    2015-03-01

    Hyperbolic optical materials (HM) are characterized by permittivity tensor that has both positive and negative principal values. Collective electromagnetic modes (polaritons) of HM have novel properties promising for various applications including subdiffractional imaging and on-chip optical communication. Hyperbolic response is actively investigated in the context of metamaterials, anisotropic polar insulators, and layered superconductors. We study polaritons in spheroidal HM nanoparticles using Hamiltonian optics. The field equations are mapped to classical dynamics of fictitious particles (wave packets) of an indefinite Hamiltonian. This dynamics is quantized using the Einstein-Brillouin-Keller quantization rule. The eigenmodes are classified as either bulk or surface according to whether their transverse momenta are real or imaginary. To model how such hyperbolic polaritons can be probed by near-field experiments, we compute the field distribution induced inside and outside the spheroid by an external point dipole. At certain magic frequencies the field shows striking geometric patterns whose origin is traced to the classical periodic orbits. The theory is applied to natural hyperbolic materials hexagonal boron nitride and superconducting LaSrCuO.

  10. Nanoparticles for transcutaneous vaccination

    PubMed Central

    Hansen, Steffi; Lehr, Claus‐Michael

    2012-01-01

    Summary The living epidermis and dermis are rich in antigen presenting cells (APCs). Their activation can elicit a strong humoral and cellular immune response as well as mucosal immunity. Therefore, the skin is a very attractive site for vaccination, and an intradermal application of antigen may be much more effective than a subcutaneous or intramuscular injection. However, the stratum corneum (SC) is a most effective barrier against the invasion of topically applied vaccines. Products which have reached the stage of clinical testing, avoid this problem by injecting the nano‐vaccine intradermally or by employing a barrier disrupting method and applying the vaccine to a relatively large skin area. Needle‐free vaccination is desirable from a number of aspects: ease of application, improved patient acceptance and less risk of infection among them. Nanocarriers can be designed in a way that they can overcome the SC. Also incorporation into nanocarriers protects instable antigen from degradation, improves uptake and processing by APCs, and facilitates endosomal escape and nuclear delivery of DNA vaccines. In addition, sustained release systems may build a depot in the tissue gradually releasing antigen which may avoid booster doses. Therefore, nanoformulations of vaccines for transcutaneous immunization are currently a very dynamic field of research. Among the huge variety of nanocarrier systems that are investigated hopes lie on ultra‐flexible liposomes, superfine rigid nanoparticles and nanocarriers, which are taken up by hair follicles. The potential and pitfalls associated with these three classes of carriers will be discussed. PMID:21854553

  11. Metal Nanoparticle Aerogel Composites

    NASA Technical Reports Server (NTRS)

    Smith, David D.; Sibille, Laurent; Ignont, Erica; Snow, Lanee; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    We have fabricated sol-gels containing gold and silver nanoparticles. Formation of an aerogel produces a blue shift in the surface plasmon resonance as a result of the decrease in the dielectric constant of the matrix upon supercritical extraction of the solvent. However, as a result of chemical interface damping this blue shift does not obey effective medium theories. Annealing the samples in a reducing atmosphere at 400 C eliminates this discrepancy and results in narrowing and further blue shifting of the plasmon resonance. Metal particle aggregation also results in a deviation from the predictions of effective medium theories, but can be controlled through careful handling and by avoiding the use of alcohol. By applying effective medium theories to the heterogeneous interlayer surrounding each metal particle, we extend the technique of immersion spectroscopy to inhomogeneous materials characterized by spatially dependent dielectric constants, such as aerogels. We demonstrate that the shift in the surface plasmon wavelength provides the average fractional composition of each component (air and silica) in this inhomogeneous layer, i.e. the porosity of the aerogel or equivalently, for these materials, the catalytic dispersion. Additionally, the kinetics suggest that collective particle interactions in coagulated metal clusters are perturbed during silica gelation resulting in a change in the aggregate geometry.

  12. Synthesis of gold nanoparticles and silver nanoparticles via green technology

    NASA Astrophysics Data System (ADS)

    Ahmed, Zulfiqaar; Balu, S. S.

    2012-11-01

    The proposed work describes the comparison of various methods of green synthesis for preparation of Gold and Silver nanoparticles. Pure extracts of Lemon (Citrus limon) and Tomato (Solanum lycopersicum) were mixed with aqueous solution of auric tetrachloride and silver nitrate. The resultant solutions were treated with four common techniques to assist in the reduction namely photo catalytic, thermal, microwave assisted reduction and solvo - thermal reduction. UV - Visible Spectroscopy results and STM images of the final solutions confirmed the formation of stable metallic nanoparticles. A preliminary account of the green synthesis work is presented here.

  13. Green chemistry for nanoparticle synthesis.

    PubMed

    Duan, Haohong; Wang, Dingsheng; Li, Yadong

    2015-08-21

    The application of the twelve principles of green chemistry in nanoparticle synthesis is a relatively new emerging issue concerning the sustainability. This field has received great attention in recent years due to its capability to design alternative, safer, energy efficient, and less toxic routes towards synthesis. These routes have been associated with the rational utilization of various substances in the nanoparticle preparations and synthetic methods, which have been broadly discussed in this tutorial review. This article is not meant to provide an exhaustive overview of green synthesis of nanoparticles, but to present several pivotal aspects of synthesis with environmental concerns, involving the selection and evaluation of nontoxic capping and reducing agents, the choice of innocuous solvents and the development of energy-efficient synthetic methods. PMID:25615873

  14. Grading plasmonic nanoparticles with light

    NASA Astrophysics Data System (ADS)

    Zharov, Alexander A.; Zharov, Alexander A.; Shadrivov, Ilya V.; Zharova, Nina A.

    2016-01-01

    We introduce an approach for fine grading of plasmonic ellipsoidal nanoparticles by two interfering light beams. We consider electrically neutral subwavelength metal nanoparticles whose response is described within the dipole approximation. For the ellipsoidal nanoparticles, we find that their polarizability tensor is strongly dispersive due to the existence of two orthogonal plasmon modes. These modes can be resonantly excited by light and the optical force experienced by particles depends on the ratio of ellipsoid semiaxes. This dependence allows us to spatially separate ellipsoidal particles with different aspect ratio. The eigenfrequencies of plasmons depend on the depolarization factor as well as on the permittivity of the environment and therefore our results can potentially be employed in a wide frequency range including near infrared, visible, and ultraviolet.

  15. Nanoparticle composites for printed electronics.

    PubMed

    Männl, U; van den Berg, C; Magunje, B; Härting, M; Britton, D T; Jones, S; van Staden, M J; Scriba, M R

    2014-03-01

    Printed Electronics is a rapidly developing sector in the electronics industry, in which nanostructured materials are playing an increasingly important role. In particular, inks containing dispersions of semiconducting nanoparticles, can form nanocomposite materials with unique electronic properties when cured. In this study we have extended on our previous studies of functional nanoparticle electronic inks, with the development of a solvent-based silicon ink for printed electronics which is compatible with existing silver inks, and with the investigation of other metal nanoparticle based inks. It is shown that both solvent-based and water-based inks can be used for both silver conductors and semiconducting silicon, and that qualitatively there is no difference in the electronic properties of the materials printed with a soluble polymer binder to when an acrylic binder is used. PMID:24521927

  16. Nanoparticles heat through light localization.

    PubMed

    Hogan, Nathaniel J; Urban, Alexander S; Ayala-Orozco, Ciceron; Pimpinelli, Alberto; Nordlander, Peter; Halas, Naomi J

    2014-08-13

    Aqueous solutions containing light-absorbing nanoparticles have recently been shown to produce steam at high efficiencies upon solar illumination, even when the temperature of the bulk fluid volume remains far below its boiling point. Here we show that this phenomenon is due to a collective effect mediated by multiple light scattering from the dispersed nanoparticles. Randomly positioned nanoparticles that both scatter and absorb light are able to concentrate light energy into mesoscale volumes near the illuminated surface of the liquid. The resulting light absorption creates intense localized heating and efficient vaporization of the surrounding liquid. Light trapping-induced localized heating provides the mechanism for low-temperature light-induced steam generation and is consistent with classical heat transfer. PMID:24960442

  17. The adjuvanticity of gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Dykman, Lev A.; Bogatyrev, Vladimir A.; Staroverov, Sergey A.; Pristensky, Dmitry V.; Shchyogolev, Sergey Yu.; Khlebtsov, Nikolai G.

    2006-06-01

    A new variant of a technique for in vivo production of antibodies to various antigens with colloidal-gold nanoparticles as carrier is discussed. With this technique we obtained highly specific and relatively high-titre antibodies to different antigens. The antibodies were tested by an immunodot assay with gold nanoparticle markers. Our results provide the first demonstration that immunization of animals with colloidal gold complexed with either haptens or complete antigens gives rise to highly specific antibodies even without the use of complete Freund's adjuvant. These findings may attest to the adjuvanticity of gold nanoparticles itself. We provide also experimental results and discussion aimed at elucidation of possible mechanisms of the discovered colloidal-gold-adjuvanticity effect.

  18. Nanoparticle composites for printed electronics

    NASA Astrophysics Data System (ADS)

    Männl, U.; van den Berg, C.; Magunje, B.; Härting, M.; Britton, D. T.; Jones, S.; van Staden, M. J.; Scriba, M. R.

    2014-03-01

    Printed Electronics is a rapidly developing sector in the electronics industry, in which nanostructured materials are playing an increasingly important role. In particular, inks containing dispersions of semiconducting nanoparticles, can form nanocomposite materials with unique electronic properties when cured. In this study we have extended on our previous studies of functional nanoparticle electronic inks, with the development of a solvent-based silicon ink for printed electronics which is compatible with existing silver inks, and with the investigation of other metal nanoparticle based inks. It is shown that both solvent-based and water-based inks can be used for both silver conductors and semiconducting silicon, and that qualitatively there is no difference in the electronic properties of the materials printed with a soluble polymer binder to when an acrylic binder is used.

  19. Polycatechol Nanoparticle MRI Contrast Agents.

    PubMed

    Li, Yiwen; Huang, Yuran; Wang, Zhao; Carniato, Fabio; Xie, Yijun; Patterson, Joseph P; Thompson, Matthew P; Andolina, Christopher M; Ditri, Treffly B; Millstone, Jill E; Figueroa, Joshua S; Rinehart, Jeffrey D; Scadeng, Miriam; Botta, Mauro; Gianneschi, Nathan C

    2016-02-01

    Amphiphilic triblock copolymers containing Fe(III) -catecholate complexes formulated as spherical- or cylindrical-shaped micellar nanoparticles (SMN and CMN, respectively) are described as new T1-weighted agents with high relaxivity, low cytotoxicity, and long-term stability in biological fluids. Relaxivities of both SMN and CMN exceed those of established gadolinium chelates across a wide range of magnetic field strengths. Interestingly, shape-dependent behavior is observed in terms of the particles' interactions with HeLa cells, with CMN exhibiting enhanced uptake and contrast via magnetic resonance imaging (MRI) compared with SMN. These results suggest that control over soft nanoparticle shape will provide an avenue for optimization of particle-based contrast agents as biodiagnostics. The polycatechol nanoparticles are proposed as suitable for preclinical investigations into their viability as gadolinium-free, safe, and effective imaging agents for MRI contrast enhancement. PMID:26681255

  20. Fabrication of transparent ceramics using nanoparticles

    DOEpatents

    Cherepy, Nerine J; Tillotson, Thomas M; Kuntz, Joshua D; Payne, Stephen A

    2012-09-18

    A method of fabrication of a transparent ceramic using nanoparticles synthesized via organic acid complexation-combustion includes providing metal salts, dissolving said metal salts to produce an aqueous salt solution, adding an organic chelating agent to produce a complexed-metal sol, heating said complexed-metal sol to produce a gel, drying said gel to produce a powder, combusting said powder to produce nano-particles, calcining said nano-particles to produce oxide nano-particles, forming said oxide nano-particles into a green body, and sintering said green body to produce the transparent ceramic.

  1. Cytotoxic Effects of Fucoidan Nanoparticles against Osteosarcoma

    PubMed Central

    Kimura, Ryuichiro; Rokkaku, Takayoshi; Takeda, Shinji; Senba, Masachika; Mori, Naoki

    2013-01-01

    In this study, we analyzed the size-dependent bioactivities of fucoidan by comparing the cytotoxic effects of native fucoidan and fucoidan lipid nanoparticles on osteosarcoma in vitro and in vivo. In vitro experiments indicated that nanoparticle fucoidan induced apoptosis of an osteosarcoma cell line more efficiently than native fucoidan. The more potent effects of nanoparticle fucoidan, relative to native fucoidan, were confirmed in vivo using a xenograft osteosarcoma model. Caco-2 cell transport studies showed that permeation of nanoparticle fucoidan was higher than native fucoidan. The higher bioactivity and superior bioavailability of nanoparticle fucoidan could potentially be utilized to develop novel therapies for osteosarcoma. PMID:24177673

  2. Synthetic pathways to make nanoparticles fluorescent

    NASA Astrophysics Data System (ADS)

    Sokolova, Viktoriya; Epple, Matthias

    2011-05-01

    In biosciences, it is often necessary to follow the pathway of nanoparticles within cells or tissues. The nanoparticles can be used as labeled sensors which may, e.g., address functionalities within a cell, carry other specific agents like drugs or be magnetic for tumor thermotherapy. In the context of nanotoxicology, the fate of a given nanoparticle is of interest. As many methods in cell biology are based on fluorescence detection, there is a strong demand to make nanoparticles fluorescent. Different ways to introduce fluorescence are reviewed and exemplified with typical kinds of nanoparticles, i.e. polymers, silica and calcium phosphate.

  3. Magnetism in nanoparticles: tuning properties with coatings.

    PubMed

    Crespo, Patricia; de la Presa, Patricia; Marín, Pilar; Multigner, Marta; Alonso, José María; Rivero, Guillermo; Yndurain, Félix; González-Calbet, José María; Hernando, Antonio

    2013-12-01

    This paper reviews the effect of organic and inorganic coatings on magnetic nanoparticles. The ferromagnetic-like behaviour observed in nanoparticles constituted by materials which are non-magnetic in bulk is analysed for two cases: (a) Pd and Pt nanoparticles, formed by substances close to the onset of ferromagnetism, and (b) Au and ZnO nanoparticles, which were found to be surprisingly magnetic at the nanoscale when coated by organic surfactants. An overview of theories accounting for this unexpected magnetism, induced by the nanosize influence, is presented. In addition, the effect of coating magnetic nanoparticles with biocompatible metals, oxides or organic molecules is also reviewed, focusing on their applications. PMID:24201075

  4. Nanoparticle Delivery Enhancement With Acoustically Activated Microbubbles

    PubMed Central

    Mullin, Lee B; Phillips, Linsey C; Dayton, Paul A

    2013-01-01

    The application of microbubbles and ultrasound to deliver nanoparticle carriers for drug and gene delivery is an area that has expanded greatly in recent years. Under ultrasound exposure, microbubbles can enhance nanoparticle delivery by increasing cellular and vascular permeability. In this review, the underlying mechanisms of enhanced nanoparticle delivery with ultrasound and microbubbles and various proposed delivery techniques are discussed. Additionally, types of nanoparticles currently being investigated in preclinical studies, as well as the general limitations and benefits of a microbubble-based approach to nanoparticle delivery are reviewed. PMID:23287914

  5. Connecting Metallic Nanoparticles by Optical Printing.

    PubMed

    Gargiulo, Julián; Cerrota, Santiago; Cortés, Emiliano; Violi, Ianina L; Stefani, Fernando D

    2016-02-10

    Optical printing is a simple and flexible method to bring colloidal nanoparticles from suspension to specific locations of a substrate. However, its application has been limited to the fabrication of arrays of isolated nanoparticles because, until now, it was never possible to bring nanoparticles closer together than approximately 300 nm. Here, we propose this limitation is due to thermophoretic repulsive forces generated by plasmonic heating of the NPs. We show how to overcome this obstacle and demonstrate the optical printing of connected nanoparticles with well-defined orientation. These experiments constitute a key step toward the fabrication by optical printing of functional nanostructures and microcircuits based on colloidal nanoparticles. PMID:26745330

  6. Polymer Functionalized Nanoparticles in Polymer Nanocomposites

    NASA Astrophysics Data System (ADS)

    Jayaraman, Arthi

    2013-03-01

    Significant interest has grown around the ability to control spatial arrangement of nanoparticles in a polymer nanocomposite to engineer materials with target properties. Past work has shown that one could achieve controlled assembly of nanoparticles in the polymer matrix by functionalizing nanoparticle surfaces with homopolymers. This talk will focus on our recent work using Polymer Reference Interaction Site Model (PRISM) theory and Monte Carlo simulations and GPU-based molecular dynamics simulations to specifically understand how heterogeneity in the polymer functionalization in the form of a) copolymers with varying monomer chemistry and monomer sequence, and b) polydispersity in homopolymer grafts can tune effective interactions between functionalized nanoparticles, and the assembly of functionalized nanoparticles.

  7. Few-layer black phosphorus nanoparticles.

    PubMed

    Sofer, Zdenek; Bouša, Daniel; Luxa, Jan; Mazanek, Vlastimil; Pumera, Martin

    2016-01-28

    Herein, black phosphorus quantum dots and nanoparticles of a few layer thickness were prepared and characterized using STEM, AFM, dynamic light scattering, X-ray photoelectron spectroscopy, X-ray diffraction, Raman spectroscopy and photoluminescence. Impact electrochemistry of the induvidual black phosphorus nanoparticles allows their size determination. The centrifugation of colloidal black phosphorus nanoparticles allowed separation of quantum dots with sizes up to 15 nm. These black phosphorus nanoparticles exhibit a large band gap and are expected to find a wide range of applications from semiconductors to biomolecule tags. The use of black phosphorus nanoparticles for vapour sensing was successfully demonstrated. PMID:26691583

  8. Heat transfer fluids containing nanoparticles

    DOEpatents

    Singh, Dileep; Routbort, Jules; Routbort, A.J.; Yu, Wenhua; Timofeeva, Elena; Smith, David S.; France, David M.

    2016-05-17

    A nanofluid of a base heat transfer fluid and a plurality of ceramic nanoparticles suspended throughout the base heat transfer fluid applicable to commercial and industrial heat transfer applications. The nanofluid is stable, non-reactive and exhibits enhanced heat transfer properties relative to the base heat transfer fluid, with only minimal increases in pumping power required relative to the base heat transfer fluid. In a particular embodiment, the plurality of ceramic nanoparticles comprise silicon carbide and the base heat transfer fluid comprises water and water and ethylene glycol mixtures.

  9. Optical Properties of Metallic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Vallée, F.

    The bright and changing colours obtained by dispersing metallic compounds in a glass matrix have been known empirically for centuries. Indeed, glasses have been coloured in the bulk by inclusion of metallic powders since ancient times to make jewellery and ornaments (see Chap. 25). Then in the Middle Ages, they were used for stained glass windows and later on for coloured glass artefacts, e.g., ruby red glass objects. However, the role played by nanoparticles in this colouring effect, i.e., the effects of nanoparticles on optical properties, were only first studied scientifically in the nineteenth century, by Michael Faraday [1].

  10. Electrochemical Nanoparticle-Based Sensors

    NASA Astrophysics Data System (ADS)

    Wang, Joseph

    Electrochemical devices are extremely useful for delivering analytical information in a fast, simple, and low-cost fashion, and are thus uniquely qualified for meeting the demands of point-of-care diagnostics. In particular, nanoparticles offer elegant ways for interfacing biomolecular recognition events with electronic signal transduction, for dramatically amplifying the resulting electrical response, and for designing novel coding strategies. Nanoparticles, such as colloidal gold or inorganic nanocrystals, offer considerable promise as quantitation tags for biological assays owing to their unique amplification and coding capabilities.