Sample records for nanosized precursor materials

  1. Nano-sized metabolic precursors for heterogeneous tumor-targeting strategy using bioorthogonal click chemistry in vivo.

    PubMed

    Lee, Sangmin; Jung, Seulhee; Koo, Heebeom; Na, Jin Hee; Yoon, Hong Yeol; Shim, Man Kyu; Park, Jooho; Kim, Jong-Ho; Lee, Seulki; Pomper, Martin G; Kwon, Ick Chan; Ahn, Cheol-Hee; Kim, Kwangmeyung

    2017-12-01

    Herein, we developed nano-sized metabolic precursors (Nano-MPs) for new tumor-targeting strategy to overcome the intrinsic limitations of biological ligands such as the limited number of biological receptors and the heterogeneity in tumor tissues. We conjugated the azide group-containing metabolic precursors, triacetylated N-azidoacetyl-d-mannosamine to generation 4 poly(amidoamine) dendrimer backbone. The nano-sized dendrimer of Nano-MPs could generate azide groups on the surface of tumor cells homogeneously regardless of cell types via metabolic glycoengineering. Importantly, these exogenously generated 'artificial chemical receptors' containing azide groups could be used for bioorthogonal click chemistry, regardless of phenotypes of different tumor cells. Furthermore, in tumor-bearing mice models, Nano-MPs could be mainly localized at the target tumor tissues by the enhanced permeation and retention (EPR) effect, and they successfully generated azide groups on tumor cells in vivo after an intravenous injection. Finally, we showed that these azide groups on tumor tissues could be used as 'artificial chemical receptors' that were conjugated to bioorthogonal chemical group-containing liposomes via in vivo click chemistry in heterogeneous tumor-bearing mice. Therefore, overall results demonstrated that our nano-sized metabolic precursors could be extensively applied to new alternative tumor-targeting technique for molecular imaging and drug delivery system, regardless of the phenotype of heterogeneous tumor cells. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. A Splash to Nano-Sized Inorganic Energy-Materials by the Low-Temperature Molecular Precursor Approach.

    PubMed

    Driess, Matthias; Panda, Chakadola; Menezes, Prashanth Wilfried

    2018-05-07

    The low-temperature synthesis of inorganic materials and their interfaces at the atomic and molecular level provides numerous opportunities for the design and improvement of inorganic materials in heterogeneous catalysis for sustainable chemical energy conversion or other energy-saving areas. Using suitable molecular precursors for functional inorganic nanomaterial synthesis allows for facile control over uniform particle size distribution, stoichiometry, and leads to desired chemical and physical properties. This minireview outlines some advantages of the molecular precursor approach in light of selected recent developments of molecule-to-nanomaterials synthesis for renewable energy applications, relevant for the oxygen evolution reaction (OER), hydrogen evolution reaction (HER) and overall water-splitting. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Advances in nanosized zeolites

    NASA Astrophysics Data System (ADS)

    Mintova, Svetlana; Gilson, Jean-Pierre; Valtchev, Valentin

    2013-07-01

    This review highlights recent developments in the synthesis of nanosized zeolites. The strategies available for their preparation (organic-template assisted, organic-template free, and alternative procedures) are discussed. Major breakthroughs achieved by the so-called zeolite crystal engineering and encompass items such as mastering and using the physicochemical properties of the precursor synthesis gel/suspension, optimizing the use of silicon and aluminium precursor sources, the rational use of organic templates and structure-directing inorganic cations, and careful adjustment of synthesis conditions (temperature, pressure, time, heating processes from conventional to microwave and sonication) are addressed. An on-going broad and deep fundamental understanding of the crystallization process, explaining the influence of all variables of this complex set of reactions, underpins an even more rational design of nanosized zeolites with exceptional properties. Finally, the advantages and limitations of these methods are addressed with particular attention to their industrial prospects and utilization in existing and advanced applications.

  4. Synthesis of Nano-Size AlN Powders by Carbothermal Reduction from Plasma-Assisted Ball Milling Precursor

    NASA Astrophysics Data System (ADS)

    Liu, Zhijie; Wang, Wenchun; Yang, Dezheng; Wang, Sen; Dai, Leyang

    2016-07-01

    Nano-size aluminum nitride (AlN) powders have been successfully synthesized with a high efficiency method through annealing from milling assisted by discharge plasma (p-milling) alumina (Al2O3) precursors. The characterization of the p-milling Al2O3 powders and the synthesized AlN are investigated. Compared to conventional ball milling (c-milling), it can be found that the precursors by p-milling have a finer grain size with a higher specific surface area, which lead to a faster reaction efficiency and higher conversion to AlN at lower temperatures. The activation energy of p-milling Al2O3 is found to be 371.5 kJ/mol, a value that is much less than the reported value of the unmilled and the conventional milled Al2O3. Meanwhile, the synthesized AlN powders have unique features, such as an irregular lamp-like morphology with uniform particle distribution and fine average particle size. The results are attributed to the unique synergistic effect of p-milling, which is the effect of deformation, fracture, and cold welding of Al2O3 powders resulting from ball milling, that will be enhanced due to the introduction of discharge plasma. supported by National Natural Science Foundation of China (No. 51177008)

  5. Nanosized copper ferrite materials: Mechanochemical synthesis and characterization

    NASA Astrophysics Data System (ADS)

    Manova, Elina; Tsoncheva, Tanya; Paneva, Daniela; Popova, Margarita; Velinov, Nikolay; Kunev, Boris; Tenchev, Krassimir; Mitov, Ivan

    2011-05-01

    Nanodimensional powders of cubic copper ferrite are synthesized by two-steps procedure of co-precipitation of copper and iron hydroxide carbonates, followed by mechanochemical treatment. X-ray powder diffraction, Mössbauer spectroscopy and temperature-programmed reduction are used for the characterization of the obtained materials. Their catalytic behavior is tested in methanol decomposition to hydrogen and CO and total oxidation of toluene. Formation of nanosized ferrite material is registered even after one hour of milling time. It is established that the prolonging of treatment procedure decreases the dispersion of the obtained product with the appearance of Fe 2O 3. It is demonstrated that the catalytic behavior of the samples depends not only on their initial phase composition, but on the concomitant ferrite phase transformations by the influence of the reaction medium.

  6. Preparation of Pt Nanocatalyst on Carbon Materials via a Reduction Reaction of a Pt Precursor in a Drying Process.

    PubMed

    Lee, Jae-Young; Lee, Woo-Kum; Rim, Hyung-Ryul; Joung, Gyu-Bum; Weidner, John W; Lee, Hong-Ki

    2016-06-01

    Platinum (Pt) nanocatalyst for a proton-exchange membrane fuel cell (PEMFC) was prepared on a carbon black particle or a graphite particle coated with a nafion polymer via a reduction of platinum(II) bis(acetylacetonate) denoted as Pt(acac)2 as a Pt precursor in a drying process. Sublimed Pt(acac)2 adsorbed on the nafion-coated carbon materials was reduced to Pt nanoparticles in a glass reactor at 180 degrees C of N2 atmosphere. The morphology of Pt nanoparticles on carbon materials was observed by scanning electron microscopy (SEM) and the distribution of Pt nanoparticles was done by transmission electron microscopy (TEM). The particle size was estimated by analyzing the TEM image using an image analyzer. It was found that nano-sized Pt particles were deposited on the surface of carbon materials, and the number density and the average particle size increased with increasing reduction time.

  7. Sonochemical syntheses of a new nano-sized porous lead(II) coordination polymer as precursor for preparation of lead(II) oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Ranjbar, Zohreh Rashidi; Morsali, Ali

    2009-11-01

    Nano-scale of a new Pb(II) coordination polymer, {[Pb(bpacb)(OAc)]·DMF} n ( 1); bpacbH = 3,5-bis[(4-pyridylamino)carbonyl]benzoic acid], were synthesized by a sonochemical method. The nano-material was characterized by scanning electron microscopy, X-ray powder diffraction (XRD), 1H, 13C NMR, IR spectroscopy and elemental analyses. Crystal structure of compound 1 was determined by X-ray crystallography. Calcination of the nano-sized compound 1 at 700 °C under air atmospheres yields PbO nanoparticles. Thermal stability of nano-sized and single crystalline samples of compound 1 were studied and compared with each other.

  8. Precursor Mediated Synthesis of Nanostructured Silicas: From Precursor-Surfactant Ion Pairs to Structured Materials.

    PubMed

    Hesemann, Peter; Nguyen, Thy Phung; Hankari, Samir El

    2014-04-11

    The synthesis of nanostructured anionic-surfactant-templated mesoporous silica (AMS) recently appeared as a new strategy for the formation of nanostructured silica based materials. This method is based on the use of anionic surfactants together with a co-structure-directing agent (CSDA), mostly a silylated ammonium precursor. The presence of this CSDA is necessary in order to create ionic interactions between template and silica forming phases and to ensure sufficient affinity between the two phases. This synthetic strategy was for the first time applied in view of the synthesis of surface functionalized silica bearing ammonium groups and was then extended on the formation of materials functionalized with anionic carboxylate and bifunctional amine-carboxylate groups. In the field of silica hybrid materials, the "anionic templating" strategy has recently been applied for the synthesis of silica hybrid materials from cationic precursors. Starting from di- or oligosilylated imidazolium and ammonium precursors, only template directed hydrolysis-polycondensation reactions involving complementary anionic surfactants allowed accessing structured ionosilica hybrid materials. The mechanistic particularity of this approach resides in the formation of precursor-surfactant ion pairs in the hydrolysis-polycondensation mixture. This review gives a systematic overview over the various types of materials accessed from this cooperative ionic templating approach and highlights the high potential of this original strategy for the formation of nanostructured silica based materials which appears as a complementary strategy to conventional soft templating approaches.

  9. Precursor Mediated Synthesis of Nanostructured Silicas: From Precursor-Surfactant Ion Pairs to Structured Materials

    PubMed Central

    Hesemann, Peter; Nguyen, Thy Phung; Hankari, Samir El

    2014-01-01

    The synthesis of nanostructured anionic-surfactant-templated mesoporous silica (AMS) recently appeared as a new strategy for the formation of nanostructured silica based materials. This method is based on the use of anionic surfactants together with a co-structure-directing agent (CSDA), mostly a silylated ammonium precursor. The presence of this CSDA is necessary in order to create ionic interactions between template and silica forming phases and to ensure sufficient affinity between the two phases. This synthetic strategy was for the first time applied in view of the synthesis of surface functionalized silica bearing ammonium groups and was then extended on the formation of materials functionalized with anionic carboxylate and bifunctional amine-carboxylate groups. In the field of silica hybrid materials, the “anionic templating” strategy has recently been applied for the synthesis of silica hybrid materials from cationic precursors. Starting from di- or oligosilylated imidazolium and ammonium precursors, only template directed hydrolysis-polycondensation reactions involving complementary anionic surfactants allowed accessing structured ionosilica hybrid materials. The mechanistic particularity of this approach resides in the formation of precursor-surfactant ion pairs in the hydrolysis-polycondensation mixture. This review gives a systematic overview over the various types of materials accessed from this cooperative ionic templating approach and highlights the high potential of this original strategy for the formation of nanostructured silica based materials which appears as a complementary strategy to conventional soft templating approaches. PMID:28788602

  10. Degradation of simazine from aqueous solutions by diatomite-supported nanosized zero-valent iron composite materials.

    PubMed

    Sun, Zhiming; Zheng, Shuilin; Ayoko, Godwin A; Frost, Ray L; Xi, Yunfei

    2013-12-15

    A novel composite material based on deposition of nanosized zero-valent iron (nZVI) particles on acid-leached diatomite was synthesised for the removal of a chlorinated contaminant in water. The nZVI/diatomite composites were characterised by X-ray diffraction, scanning electron microscopy, elemental analysis, transmission electron microscopy and X-ray photoelectron spectroscopy. Compared with the pure nZVI particles, better dispersion of nZVI particles on the surface or inside the pores of diatom shells was observed. The herbicide simazine was selected as the model chlorinated contaminant and the removal efficiency by nZVI/diatomite composite was compared with that of the pristine nZVI and commercial iron powder. It was found that the diatomite supported nZVI composite material prepared by centrifugation exhibits relatively better efficient activity in decomposition of simazine than commercial Fe, lab synthesised nZVI and composite material prepared via rotary evaporation, and the optimum experimental conditions were obtained based on a series of batch experiments. This study on immobilising nZVI particles onto diatomite opens a new avenue for the practical application of nZVI and the diatomite-supported nanosized zero-valent iron composite materials have potential applications in environmental remediation. Copyright © 2013 Elsevier B.V. All rights reserved.

  11. Catalytic transformation of persistent contaminants using a new composite material based on nanosized zero-valent metal - field experiment results

    NASA Astrophysics Data System (ADS)

    Dror, I.; Merom Jacov, O.; Berkowitz, B.

    2010-12-01

    A new composite material based on deposition of nanosized zero valent iron (ZVI) particles and cyanocobalamine (vitamin B12) on a diatomite matrix is presented. Cyanocobalamine is known to be an effective electron mediator, having strong synergistic effects with ZVI for reductive dehalogenation reactions. This composite material also improves the reducing capacity of nanosized ZVI by preventing agglomeration of iron particles, thus increasing their active surface area. The porous structure of the diatomite matrix allows high hydraulic conductivity, which favors channeling of contaminated water to the reactive surface of the composite material and in turn faster rates of remediation. The ability of the material to degrade or transform rapidly and completely a large spectrum of water pollutants will be demonstrated, based on results from two field site experiments where polluted groundwater containing a mixture of industrial and agricultural persistent pollutants was treated. In addition a set of laboratory experiments using individual contaminant solutions to analyze chemical transformations under controlled conditions will be presented.

  12. No time to waste organic waste: Nanosizing converts remains of food processing into refined materials.

    PubMed

    Griffin, Sharoon; Sarfraz, Muhammad; Farida, Verda; Nasim, Muhammad Jawad; Ebokaiwe, Azubuike P; Keck, Cornelia M; Jacob, Claus

    2018-03-15

    Modern food processing results in considerable amounts of side-products, such as grape seeds, walnut shells, spent coffee grounds, and harvested tomato plants. These materials are still rich in valuable and biologically active substances and therefore of interest from the perspective of waste management and "up-cycling". In contrast to traditional, often time consuming and low-value uses, such as vermicomposting and anaerobic digestion, the complete conversion into nanosuspensions unlocks considerable potentials of and new applications for such already spent organic materials without the need of extraction and without producing any additional waste. In this study, nanosuspensions were produced using a sequence of milling and homogenization methods, including High Speed Stirring (HSS) and High Pressure Homogenization (HPH) which reduced the size of the particles to 200-400 nm. The resulting nanosuspensions demonstrated nematicidal and antimicrobial activity and their antioxidant activities exceeded the ones of the bulk materials. In the future, this simple nanosizing approach may fulfil several important objectives, such as reducing and turning readily available waste into new value and eventually closing a crucial cycle of agricultural products returning to their fields - with a resounding ecological impact in the fields of medicine, agriculture, cosmetics and fermentation. Moreover, up-cycling via nanosizing adds an economical promise of increased value to residue-free waste management. Copyright © 2018 Elsevier Ltd. All rights reserved.

  13. Synthesis and LPG sensing properties of nano-sized cadmium oxide.

    PubMed

    Waghulade, R B; Patil, P P; Pasricha, Renu

    2007-04-30

    This paper reports the synthesis and liquid petroleum gas (LPG) sensing properties of nano-sized cadmium oxide (CdO). The nano-sized CdO powder was successfully synthesized by using a chemical co-precipitation method using cadmium acetate and the ammonium hydroxide, as starting materials and water as a carrier. The resulting nano-sized powder was characterized by X-ray diffraction (XRD) measurements and the transmission electron microscopy (TEM). The LPG sensing properties of the synthesized nano-sized CdO were investigated at different operating temperatures and LPG concentrations. It was found that the calcination temperature and the operating temperature significantly affect the sensitivity of the nano-sized CdO powder to the LPG. The sensitivity is found to be maximum when the calcination temperature was 400 degrees C. The sensitivity to 75ppm of LPG is maximum at an operating temperature 450 degrees C and it was found to be approximately 341%. The response and recovery times were found to be nearly 3-5s and 8-10s, respectively. The synthesized nano-sized CdO powder is able to detect up to 25ppm for LPG with reasonable sensitivity at an operating temperature 450 degrees C and it can be reliably used to monitor the concentration of LPG over the range (25-75ppm). The experimental results of the LPG sensing studies reveal that the nano-sized CdO powder synthesized by a simple co-precipitation method is a suitable material for the fabrication of the LPG sensor.

  14. Synthesis, Dielectric, Electrical and Optical characterization of ZnO synthesized by chemical route using polymer precursors

    NASA Astrophysics Data System (ADS)

    Mishra, Raman; Bajpai, P. K.

    2011-11-01

    Nano-size ZnO (particle size 7.8 nm) have been prepared from a versatile, efficient and technically simple polymer matrix based precursor solution. The precursor solution constituted of zinc nitrates with polymer PVA in presence of mono-/disaccharides. Annealing the precursor mass at 900 °C single phase zinc oxide nano-particles are obtained. X-ray diffraction analysis confirms hexagonal crystal structure with lattice parameter a = b = 3.261 A0, c = 5.220 A0. The estimated average particle size obtained from XRD data is ≈7.8 nm. The impedance analysis reveals that the grain resistance decreases with increase in temperature as expected for a semi-conducting material. The relaxation is polydispersive and conduction is mainly through grains. Optical properties and AC/DC conduction activation energies are estimated from Arrhenius plots and conduction mechanism is discussed.

  15. Chemical precursors to non-oxide ceramics: Macro to nanoscale materials

    NASA Astrophysics Data System (ADS)

    Forsthoefel, Kersten M.

    Non-oxide ceramics exhibit a number of important properties that make them ideal for technologically important applications (thermal and chemical stability, high strength and hardness, wear-resistance, light weight, and a range of electronic and optical properties). Unfortunately, traditional methodologies to these types of materials are limited to fairly simple shapes and complex processed forms cannot be attained through these methods. The establishment of the polymeric precursor approach has allowed for the generation of advanced materials, such as refractory non-oxide ceramics, with controlled compositions, under moderate conditions, and in processed forms. The goal of the work described in this dissertation was both to develop new processible precursors to technologically important ceramics and to achieve the formation of advanced materials in processed forms. One aspect of this research exploited previously developed preceramic precursors to boron carbide, boron nitride and silicon carbide for the generation of a wide variety of advanced materials: (1) ultra-high temperature ceramic (UHTC) structural materials composed of hafnium boride and related composite materials, (2) the quaternary borocarbide superconductors, and (3) on the nanoscale, non-oxide ceramic nanotubules. The generation of the UHTC and the quaternary borocarbide materials was achieved through a method that employs a processible polymer/metal(s) dispersion followed by subsequent pyrolyses. In the case of the UHTC, hafnium oxide, hafnium, or hafnium boride powders were dispersed in a suitable precursor to afford hafnium borides or related composite materials (HfB2/HfC, HfB2/HfN, HfB2/SiC) in high yields and purities. The quaternary borocarbide superconducting materials were produced from pyrolyses of dispersions containing appropriate stoichiometric amounts of transition metal, lanthanide metal, and the polyhexenyldecaborane polymer. Both chemical vapor deposition (CVD) based routes employing a

  16. Ultrasmall Zeolite L Crystals Prepared from Highly-Interdispersed Alkali-Silicate Precursors.

    PubMed

    Li, Rui; Linares, Noemi; Sutjianto, James G; Chawla, Aseem; Garcia Martinez, Javier; Rimer, Jeffrey D

    2018-06-19

    The preparation of nanosized zeolites is critical for applications where mass transport limitations within microporous networks hinder their performance. Oftentimes the ability to generate ultrasmall zeolite crystals is dependent upon the use of expensive organics with limited commercial relevance. Here, we report the generation of zeolite L crystals with uniform sizes less than 30 nm using a facile, organic-free method. Time-resolved analysis of precursor assembly and evolution during nonclassical crystallization highlights key differences among silicon sources. Our findings reveal that a homogenous dispersion of potassium ions throughout silicate precursors is critical to enhancing the rate of nucleation and facilitating the formation of ultrasmall crystals. Intimate contact between the inorganic structure-directing agent and silica leads to the formation of a metastable nonporous phase, identified as KAlSi2O6, which undergoes an intercrystalline transformation to zeolite L. The presence of highly-interdispersed alkali-silicate precursors is seemingly integral to a reduced zeolite induction time and may facilitate the development of ultrasmall crystals. Given the general difficulty of achieving nanosized crystals in zeolite synthesis, it is likely that using well-dispersed precursors does not have the same effect on all framework types; however, in select cases it may provide an alternative strategy for optimizing zeolite synthesis. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Porous carbon nanotubes decorated with nanosized cobalt ferrite as anode materials for high-performance lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Wang, Lingyan; Zhuo, Linhai; Cheng, Haiyang; Zhang, Chao; Zhao, Fengyu

    2015-06-01

    Generally, the fast ion/electron transport and structural stability dominate the superiority in lithium-storage applications. In this work, porous carbon nanotubes decorated with nanosized CoFe2O4 particles (p-CNTs@CFO) have been rationally designed and synthesized by the assistance of supercritical carbon dioxide (scCO2). When tested as anode materials for lithium-ion batteries, the p-CNTs@CFO composite exhibits outstanding electrochemical behavior with high lithium-storage capacity (1077 mAh g-1 after 100 cycles) and rate capability (694 mAh g-1 at 3 A g-1). These outstanding electrochemical performances are attributed to the synergistic effect of porous p-CNTs and nanosized CFO. Compared to pristine CNTs, the p-CNTs with substantial pores in the tubes possess largely increased specific surface area and rich oxygen-containing functional groups. The porous structure can not only accommodate the volume change during lithiation/delithiation processes, but also provide bicontinuous electron/ion pathways and large electrode/electrolyte interface, which facilitate the ion diffusion kinetics, improving the rate performance. Moreover, the CFO particles are bonded strongly to the p-CNTs through metal-oxygen bridges, which facilitate the electron fast capture from p-CNTs to CFO, and thus resulting in a high reversible capacity and excellent rate performance. Overall, the porous p-CNTs provide an efficient way for ion diffusion and continuous electron transport as anode materials.

  18. Turning Waste into Value: Nanosized Natural Plant Materials of Solanum incanum L. and Pterocarpus erinaceus Poir with Promising Antimicrobial Activities

    PubMed Central

    Griffin, Sharoon; Tittikpina, Nassifatou Koko; Al-marby, Adel; Alkhayer, Reem; Denezhkin, Polina; Witek, Karolina; Gbogbo, Koffi Apeti; Batawila, Komlan; Duval, Raphaël Emmanuel; Nasim, Muhammad Jawad; Awadh-Ali, Nasser A.; Kirsch, Gilbert; Chaimbault, Patrick; Schäfer, Karl-Herbert; Keck, Cornelia M.; Handzlik, Jadwiga; Jacob, Claus

    2016-01-01

    Numerous plants are known to exhibit considerable biological activities in the fields of medicine and agriculture, yet access to their active ingredients is often complicated, cumbersome and expensive. As a consequence, many plants harbouring potential drugs or green phyto-protectants go largely unnoticed, especially in poorer countries which, at the same time, are in desperate need of antimicrobial agents. As in the case of plants such as the Jericho tomato, Solanum incanum, and the common African tree Pterocarpus erinaceus, nanosizing of original plant materials may provide an interesting alternative to extensive extraction and isolation procedures. Indeed, it is straightforward to obtain considerable amounts of such common, often weed-like plants, and to mill the dried material to more or less uniform particles of microscopic and nanoscopic size. These particles exhibit activity against Steinernema feltiae or Escherichia coli, which is comparable to the ones seen for processed extracts of the same, respective plants. As S. feltiae is used as a model nematode indicative of possible phyto-protective uses in the agricultural arena, these findings also showcase the potential of nanosizing of crude “waste” plant materials for specific practical applications, especially—but not exclusively—in developing countries lacking a more sophisticated industrial infrastructure. PMID:27104554

  19. A polymer solution technique for the synthesis of nano-sized Li 2TiO 3 ceramic breeder powders

    NASA Astrophysics Data System (ADS)

    Jung, Choong-Hwan; Lee, Sang Jin; Kriven, Waltraud M.; Park, Ji-Yeon; Ryu, Woo-Seog

    2008-02-01

    Nano-sized Li 2TiO 3 powder was fabricated by an organic-inorganic solution route. A steric entrapment route employing ethylene glycol was used for the preparation of the nano-sized Li 2TiO 3 particles. Titanium isopropoxide and lithium nitrate were dissolved in liquid-type ethylene glycol without any precipitation. With the optimum amount of the polymer, the metal cations (Li and Ti) were dispersed in the solution and a homogeneous polymeric network was formed. The organic-inorganic precursor gels were turned to crystalline powders through an oxidation reaction during a calcination process. The dried precursor gel showed the carbon-free Li 2TiO 3 crystalline form which was observed above 400 °C. The primary particle size of the carbon-free Li 2TiO 3 was about 70 nm, and the structure of the crystallized powder was porous and agglomerated. The powder compact was densified to 92% of TD at a relatively low sintering temperature of 1100 °C for 2 h.

  20. Nanosized Selenium: A Novel Platform Technology to Prevent Bacterial Infections

    NASA Astrophysics Data System (ADS)

    Wang, Qi

    As an important category of bacterial infections, healthcare-associated infections (HAIs) are considered an increasing threat to the safety and health of patients worldwide. HAIs lead to extended hospital stays, contribute to increased medical costs, and are a significant cause of morbidity and mortality. In the United States, infections encountered in the hospital or a health care facility affect more than 1.7 million patients, cost 35.7 billion to 45 billion, and contribute to 88,000 deaths in hospitals annually. The most conventional and widely accepted method to fight against bacterial infections is using antibiotics. However, because of the widespread and sometimes inappropriate use of antibiotics, many strains of bacteria have rapidly developed antibiotic resistance. Those new, stronger bacteria pose serious, worldwide threats to public health and welfare. In 2014, the World Health Organization (WHO) reported antibiotic resistance as a global serious threat that is no longer a prediction for the future but is now reality. It has the potential to affect anyone, of any age, in any country. The most effective strategy to prevent antibiotic resistance is minimizing the use of antibiotics. In recent years, nanomaterials have been investigated as one of the potential substitutes of antibiotics. As a result of their vastly increased ratio of surface area to volume, nanomaterials will likely exert a stronger interaction with bacteria which may affect bacterial growth and propagation. A major concern of most existing antibacterial nanomaterials, like silver nanoparticles, is their potential toxicity. But selenium is a non-metallic material and a required nutrition for the human body, which is recommended by the FDA at a 53 to 60 μg daily intake. Nanosized selenium is considered to be healthier and less toxic compared with many metal-based nanomaterials due to the generation of reactive oxygen species from metals, especially heavy metals. Therefore, the objectives of

  1. Development of nanosized silver-substituted apatite for biomedical applications: A review.

    PubMed

    Lim, Poon Nian; Chang, Lei; Thian, Eng San

    2015-08-01

    The favorable biocompatibility of hydroxyapatite (HA) makes it a popular bone graft material as well as a coating layer on metallic implant. To reduce implant-related infections, silver ions were either incorporated into the apatite during co-precipitation process (AgHA-CP) or underwent ion-exchange with the calcium ions in the apatite (AgHA-IE). However, the distribution of silver ions in AgHA-CP and AgHA-IE was different, thus affecting the antibacterial action. Several studies reported that nanosized AgHA-CP containing 0.5 wt.% of silver provided an optimal trade-off between antibacterial properties and cytotoxicity. Nevertheless, nanosized AgHA and AgHA nanocoatings could not function ideally due to the compromise in the bone differentiation of mesenchymal stem cells, as evidenced in the reduced alkaline phosphatase, type I collagen and osteocalcin. Preliminary studies showed that biological responses of nanosized AgHA and AgHA nanocoatings could be improved with the addition of silicon. This review will discuss on nanosized AgHA and AgHA nanocoatings. In many patients needing bone graft material, hydroxyapatite (HA) has proven to be a popular choice. Nonetheless, implant-related infections remain a major concern. Hence, effective preventive measures are needed. In this review article, the authors discussed the application of incorporating silver nanoparticles in HA and its use as bone graft biomaterials together with the addition of silica. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Catalytic transformation of persistent contaminants using a new composite material based on nanosized zero-valent iron.

    PubMed

    Dror, Ishai; Jacov, Osnat Merom; Cortis, Andrea; Berkowitz, Brian

    2012-07-25

    A new composite material based on deposition of nanosized zerovalent iron (nZVI) particles and cyanocobalamine (vitamin B12) on a diatomite matrix is presented, for catalytic transformation of organic contaminants in water. Cyanocobalamine is known to be an effective electron mediator, having strong synergistic effects with nZVI for reductive dehalogenation reactions. This composite material also improves the reducing capacity of nZVI by preventing agglomeration of iron nanoparticles, thus increasing their active surface area. The porous structure of the diatomite matrix allows high hydraulic conductivity, which favors channeling of contaminated water to the reactive surface of the composite material resulting in faster rates of remediation. The composite material rapidly degrades or transforms completely a large spectrum of water contaminants, including halogenated solvents like TCE, PCE, and cis-DCE, pesticides like alachlor, atrazine and bromacyl, and common ions like nitrate, within minutes to hours. A field experiment where contaminated groundwater containing a mixture of industrial and agricultural persistent pollutants was conducted together with a set of laboratory experiments using individual contaminant solutions to analyze chemical transformations under controlled conditions.

  3. Synthesis of nanosized sodium titanates

    DOEpatents

    Hobbs, David T.; Taylor-Pashow, Kathryn M. L.; Elvington, Mark C.

    2015-09-29

    Methods directed to the synthesis and peroxide-modification of nanosized monosodium titanate are described. Methods include combination of reactants at a low concentration to a solution including a nonionic surfactant. The nanosized monosodium titanate can exhibit high selectivity for sorbing various metallic ions.

  4. Synthesis of nanosize MCM-41 loaded with TiO 2 and study of its photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Sadjadi, M. S.; Farhadyar, N.; Zare, K.

    2009-07-01

    In recent years, nanosized mesoporous materials have received significant attention due to their impact in different processes. Several diverse applications of these materials, e.g. high density magnetic recording, magnetic fluids, magnetic refrigeration as well as in photocatalysis, solar cells, photosensors, have triggered considerable research activities in the area of nanotechnology. In this work, nanosize MCM-41 was synthesized and loaded then with TiO 2 using tetra butoxy titanium (TBT). As prepared TiO 2 loaded materials was investigated by using X-ray diffraction (XRD), Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR). The photocatalytic activity of the prepared TiO 2 loaded MCM-41 was finally evaluated by the degradation of methyl orange under irradiation of UV light. The result showed that TiO 2 loaded on nanosize MCM-41 has higher photocatalytic activity than that of TiO 2.

  5. Emission properties of Ce3+ centers in barium borate glasses prepared from different precursor materials

    NASA Astrophysics Data System (ADS)

    Torimoto, Aya; Masai, Hirokazu; Okada, Go; Kawaguchi, Noriaki; Yanagida, Takayuki; Ohkubo, Takahiro

    2017-10-01

    The photoluminescence (PL) and X-ray induced luminescence properties of Ce-doped barium borate glasses prepared from different precursor materials have been investigated. Oxidation of Ce3+ takes place during the melting process performed using a pre-vitrified non-doped glass. Residual groups originated from the precursor materials, such as fluorine atoms and OH groups, are found to affect the optical and emission properties of the glasses. Moreover, both the PL and the X-ray induced luminescence properties of the glasses depend on the precursor materials used for their synthesis. Based on a thorough analysis of the emission properties, we conclude that the best synthesis conditions involve melting a batch containing Ce(CH3COO)3·H2O, BaCO3, and B2O3 in Ar atmosphere.

  6. Novel materials for electrochemical power sources—introduction of PUREBLACK ® Carbons

    NASA Astrophysics Data System (ADS)

    Barsukov, Igor V.; Gallego, Maritza A.; Doninger, Joseph E.

    Graphitization heat treatment of a precursor carbon black was seen to effectively produce a wide variety of forms of partially graphitized nano-sized carbonaceous materials with a set of unique properties, some of which are reported in this paper in comparison with those properties of the precursor carbon material. These novel materials were given the name of PUREBLACK ® Carbons. Among some of the unique properties are: higher conductivity than that of acetylene type carbon blacks due to PUREBLACK ® Carbon's particles having more graphitic structure; very low to zero volatile content (external oxygen, sulfur, etc., groups, which are often believed to be the cause of initiation of self-discharge reactions in batteries); very low equilibrium moisture pickup (20 ppm level), which makes it particularly attractive in lithium metal or lithium-ion based electrochemical systems; high purity. Electrochemical testing of the newly proposed PUREBLACK ® Carbons in several battery systems offers significant promise that it presents a viable solution to the needs of industry.

  7. Characteristics of nano-sized yttria powder synthesized by a polyvinyl alcohol solution route at low temperature.

    PubMed

    Lee, Sang-Jin; Jung, Choong-Hwan

    2012-01-01

    Nano-sized yttria (Y2O3) powders were successfully synthesized at a low temperature of 400 degrees C by a simple polymer solution route. PVA polymer, as an organic carrier, contributed to an atom-scale homogeneous precursor gel and it resulted in fully crystallized, nano-sized yttria powder with high specific surface area through the low temperature calcination. In this process, the content of PVA, calcination temperature and heating time affected the microstructure and crystallization behavior of the powders. The development of crystalline phase and the final particle size were strongly dependant on the oxidation reaction from the polymer burn-out step and the PVA content. In this paper, the PVA solution technique for the fabrication of nano-sized yttria powders is introduced. The effects of PVA content and holding time on the powder morphology and powder specific surface area are also studied. The characterization of the synthesized powders is examined by using XRD, DTA/TG, SEM, TEM and nitrogen gas adsorption. The yttria powder synthesized from the PVA content of 3:1 ratio and calcined at 400 degrees C had a crystallite size of about 20 nm or less with a high surface areas of 93.95-120.76 m2 g(-1).

  8. Multi-wall carbon nanotube@zeolite imidazolate framework composite from a nanoscale zinc oxide precursor

    DOE PAGES

    Yue, Yanfeng; Guo, Bingkun; Qiao, Zhenan; ...

    2014-07-24

    Nanocomposite of multi-walled carbon nanotube@zeolite imidazolate frameworks (MWNT@ZIF) was prepared through a nanotube-facilitated growth based on a nanosized ZnO precursor. The electrically conductive nanocomposite displays a capacity of 380 mAh/g at 0.1 °C in Li–sulfur battery, transforming electrically inactive ZIF into the active one for battery applications.

  9. Determination of NH(3) gas by combination of nanosized LaCoO(3) converter with chemiluminescence detector.

    PubMed

    Shi, Jinjun; Yan, Ruoxue; Zhu, Yongfa; Zhang, Xinrong

    2003-10-17

    Combination of a novel NH(3) converter based on nanosized materials with chemiluminescence (CL) detector for the determination of NH(3) gas was demonstrated in this paper. NH(3) gas is oxidized on different nanosized catalysts to produce NO(x), which can react with luminol to generate CL emission. Eight nanosized materials were investigated as catalyst, and CL was detected from seven of them. The nanosized LaCoO(3) was chosen as the catalyst for preparing the converter because of its higher activity than others. Under the optimized conditions, the linear range of CL intensity versus concentration of NH(3) gas is 0.04-10 ppm (r=0.9951, n=14) with the detection limit of 0.014 ppm. The method offers advantages of long lifetime of the converter, fast response and high selectivity to NH(3). There was no response while the foreign substances, such as hydrogen, oxygen, nitrogen, formaldehyde, acetone and gasoline passing through the CL detection system, and the interference of CCl(4), ethanol, ethylene and toluene was insignificant.

  10. Single-source precursors for ternary chalcopyrite materials, and methods of making and using the same

    NASA Technical Reports Server (NTRS)

    Banger, Kulbinder K. (Inventor); Hepp, Aloysius F. (Inventor); Harris, Jerry D. (Inventor); Jin, Michael Hyun-Chul (Inventor); Castro, Stephanie L. (Inventor)

    2006-01-01

    A single source precursor for depositing ternary I-III-VI.sub.2 chalcopyrite materials useful as semiconductors. The single source precursor has the I-III-VI.sub.2 stoichiometry built into a single precursor molecular structure which degrades on heating or pyrolysis to yield the desired I-III-VI.sub.2 ternary chalcopyrite. The single source precursors effectively degrade to yield the ternary chalcopyrite at low temperature, e.g. below 500.degree. C., and are useful to deposit thin film ternary chalcopyrite layers via a spray CVD technique. The ternary single source precursors according to the invention can be used to provide nanocrystallite structures useful as quantum dots. A method of making the ternary single source precursors is also provided.

  11. Influence of nanosize clay platelets on the mechanical properties of glass fiber reinforced polyester composites.

    PubMed

    Jawahar, P; Balasubramanian, M

    2006-12-01

    Glass fiber reinforced polyester composite and hybrid nanoclay-fiber reinforced composites were prepared by hand lay-up process. The mechanical behavior of these materials and the changes as a result of the incorporation of both nanosize clay and glass fibers were investigated. Composites were prepared with a glass fibre content of 25 vol%. The proportion of the nanosize clay platelets was varied from 0.5 to 2.5 vol%. Hybrid clay-fiber reinforced polyester composite posses better tensile, flexural, impact, and barrier properties. Hybrid clay-fiber reinforced polyester composites also posses better shear strength, storage modulus, and glass transition temperature. The optimum properties were found to be with the hybrid laminates containing 1.5 vol% nanosize clay.

  12. Nano-sized structured layered positive electrode materials to enable high energy density and high rate capability lithium batteries

    DOEpatents

    Deng, Haixia; Belharouak, Ilias; Amine, Khalil

    2012-10-02

    Nano-sized structured dense and spherical layered positive active materials provide high energy density and high rate capability electrodes in lithium-ion batteries. Such materials are spherical second particles made from agglomerated primary particles that are Li.sub.1+.alpha.(Ni.sub.xCo.sub.yMn.sub.z).sub.1-tM.sub.tO.sub.2-dR.sub.d- , where M is selected from can be Al, Mg, Fe, Cu, Zn, Cr, Ag, Ca, Na, K, In, Ga, Ge, V, Mo, Nb, Si, Ti, Zr, or a mixture of any two or more thereof, R is selected from F, Cl, Br, I, H, S, N, or a mixture of any two or more thereof, and 0.ltoreq..alpha..ltoreq.0.50; 0materials and their use in electrochemical devices are also described.

  13. Material State Awareness for Composites Part II: Precursor Damage Analysis and Quantification of Degraded Material Properties Using Quantitative Ultrasonic Image Correlation (QUIC)

    PubMed Central

    Patra, Subir; Banerjee, Sourav

    2017-01-01

    Material state awareness of composites using conventional Nondestructive Evaluation (NDE) method is limited by finding the size and the locations of the cracks and the delamination in a composite structure. To aid the progressive failure models using the slow growth criteria, the awareness of the precursor damage state and quantification of the degraded material properties is necessary, which is challenging using the current NDE methods. To quantify the material state, a new offline NDE method is reported herein. The new method named Quantitative Ultrasonic Image Correlation (QUIC) is devised, where the concept of microcontinuum mechanics is hybrid with the experimentally measured Ultrasonic wave parameters. This unique combination resulted in a parameter called Nonlocal Damage Entropy for the precursor awareness. High frequency (more than 25 MHz) scanning acoustic microscopy is employed for the proposed QUIC. Eight woven carbon-fiber-reinforced-plastic composite specimens were tested under fatigue up to 70% of their remaining useful life. During the first 30% of the life, the proposed nonlocal damage entropy is plotted to demonstrate the degradation of the material properties via awareness of the precursor damage state. Visual proofs for the precursor damage states are provided with the digital images obtained from the micro-optical microscopy, the scanning acoustic microscopy and the scanning electron microscopy. PMID:29258256

  14. A Review of Single Source Precursors for the Deposition of Ternary Chalcopyrite Materials

    NASA Technical Reports Server (NTRS)

    Banger, K. K.; Cowen, J.; Harris, J.; McClarnon, R.; Hehemann, D. G.; Duraj, S. A.; Scheiman, D.; Hepp, A. F.

    2002-01-01

    The development of thin-film solar cells on flexible, lightweight, space-qualified durable substrates (i.e. Kapton) provides an attractive solution to fabricating solar arrays with high specific power, (W/kg). The syntheses and thermal modulation of ternary single source precursors, based on the [{LR}2Cu(SR')2In(SR')2] architecture in good yields are described. Thermogravimetric analyses (TGA) and Low temperature Differential Scanning Caloriometry, (DSC) demonstrate that controlled manipulation of the steric and electronic properties of either the group five-donor and/or chalcogenide moiety permits directed adjustment of the thermal stability and physical properties of the precursors. TGA-Evolved Gas Analysis, confirms that single precursors decompose by the initial extrusion of the sulphide moiety, followed by the loss of the neutral donor group, (L) to release the ternary chalcopyrite matrix. X-ray diffraction studies, EDS and SEM on the non-volatile pyrolized material demonstrate that these derivatives afford single-phase CuInS2/CuInSe2 materials at low temperature. Thin-film fabrication studies demonstrate that these single source precursors can be used in a spray chemical vapor deposition process, for depositing CuInS2 onto flexible polymer substrates at temperatures less than 400 C.

  15. Material State Awareness for Composites Part I: Precursor Damage Analysis Using Ultrasonic Guided Coda Wave Interferometry (CWI).

    PubMed

    Patra, Subir; Banerjee, Sourav

    2017-12-16

    Detection of precursor damage followed by the quantification of the degraded material properties could lead to more accurate progressive failure models for composite materials. However, such information is not readily available. In composite materials, the precursor damages-for example matrix cracking, microcracks, voids, interlaminar pre-delamination crack joining matrix cracks, fiber micro-buckling, local fiber breakage, local debonding, etc.-are insensitive to the low-frequency ultrasonic guided-wave-based online nondestructive evaluation (NDE) or Structural Health Monitoring (SHM) (~100-~500 kHz) systems. Overcoming this barrier, in this article, an online ultrasonic technique is proposed using the coda part of the guided wave signal, which is often neglected. Although the first-arrival wave packets that contain the fundamental guided Lamb wave modes are unaltered, the coda wave packets however carry significant information about the precursor events with predictable phase shifts. The Taylor-series-based modified Coda Wave Interferometry (CWI) technique is proposed to quantify the stretch parameter to compensate the phase shifts in the coda wave as a result of precursor damage in composites. The CWI analysis was performed on five woven composite-fiber-reinforced-laminate specimens, and the precursor events were identified. Next, the precursor damage states were verified using high-frequency Scanning Acoustic Microscopy (SAM) and optical microscopy imaging.

  16. Modifications in Glass Ionomer Cements: Nano-Sized Fillers and Bioactive Nanoceramics

    PubMed Central

    Najeeb, Shariq; Khurshid, Zohaib; Zafar, Muhammad Sohail; Khan, Abdul Samad; Zohaib, Sana; Martí, Juan Manuel Nuñez; Sauro, Salvatore; Matinlinna, Jukka Pekka; Rehman, Ihtesham Ur

    2016-01-01

    Glass ionomer cements (GICs) are being used for a wide range of applications in dentistry. In order to overcome the poor mechanical properties of glass ionomers, several modifications have been introduced to the conventional GICs. Nanotechnology involves the use of systems, modifications or materials the size of which is in the range of 1–100 nm. Nano-modification of conventional GICs and resin modified GICs (RMGICs) can be achieved by incorporation of nano-sized fillers to RMGICs, reducing the size of the glass particles, and introducing nano-sized bioceramics to the glass powder. Studies suggest that the commercially available nano-filled RMGIC does not hold any significant advantage over conventional RMGICs as far as the mechanical and bonding properties are concerned. Conversely, incorporation of nano-sized apatite crystals not only increases the mechanical properties of conventional GICs, but also can enhance fluoride release and bioactivity. By increasing the crystallinity of the set matrix, apatites can make the set cement chemically more stable, insoluble, and improve the bond strength with tooth structure. Increased fluoride release can also reduce and arrest secondary caries. However, due to a lack of long-term clinical studies, the use of nano-modified glass ionomers is still limited in daily clinical dentistry. In addition to the in vitro and in vivo studies, more randomized clinical trials are required to justify the use of these promising materials. The aim of this paper is to review the modification performed in GIC-based materials to improve their physicochemical properties. PMID:27428956

  17. Solution properties and spectroscopic characterization of polymeric precursors to SiNCB and BN ceramic materials

    NASA Astrophysics Data System (ADS)

    Cortez, E.; Remsen, E.; Chlanda, V.; Wideman, T.; Zank, G.; Carrol, P.; Sneddon, L.

    1998-06-01

    Boron Nitride, BN, and composite SiNCB ceramic fibers are important structural materials because of their excellent thermal and oxidative stabilities. Consequently, polymeric materials as precursors to ceramic composites are receiving increasing attention. Characterization of these materials requires the ability to evaluate simultaneous molecular weight and compositional heterogeneity within the polymer. Size exclusion chromatography equipped with viscometric and refractive index detection as well as coupled to a LC-transform device for infrared absorption analysis has been employed to examine these heterogeneities. Using these combined approaches, the solution properties and the relative amounts of individual functional groups distributed through the molecular weight distribution of SiNCB and BN polymeric precursors were characterized.

  18. Presence of nano-sized silica during in vitro digestion of foods containing silica as a food additive.

    PubMed

    Peters, Ruud; Kramer, Evelien; Oomen, Agnes G; Rivera, Zahira E Herrera; Oegema, Gerlof; Tromp, Peter C; Fokkink, Remco; Rietveld, Anton; Marvin, Hans J P; Weigel, Stefan; Peijnenburg, Ad A C M; Bouwmeester, Hans

    2012-03-27

    The presence, dissolution, agglomeration state, and release of materials in the nano-size range from food containing engineered nanoparticles during human digestion is a key question for the safety assessment of these materials. We used an in vitro model to mimic the human digestion. Food products subjected to in vitro digestion included (i) hot water, (ii) coffee with powdered creamer, (iii) instant soup, and (iv) pancake which either contained silica as the food additive E551, or to which a form of synthetic amorphous silica or 32 nm SiO(2) particles were added. The results showed that, in the mouth stage of the digestion, nano-sized silica particles with a size range of 5-50 and 50-500 nm were present in food products containing E551 or added synthetic amorphous silica. However, during the successive gastric digestion stage, this nano-sized silica was no longer present for the food matrices coffee and instant soup, while low amounts were found for pancakes. Additional experiments showed that the absence of nano-sized silica in the gastric stage can be contributed to an effect of low pH combined with high electrolyte concentrations in the gastric digestion stage. Large silica agglomerates are formed under these conditions as determined by DLS and SEM experiments and explained theoretically by the extended DLVO theory. Importantly, in the subsequent intestinal digestion stage, the nano-sized silica particles reappeared again, even in amounts higher than in the saliva (mouth) digestion stage. These findings suggest that, upon consumption of foods containing E551, the gut epithelium is most likely exposed to nano-sized silica. © 2012 American Chemical Society

  19. Design and synthesis of single-source molecular precursors to homogeneous multi-component oxide materials

    NASA Astrophysics Data System (ADS)

    Fujdala, Kyle Lee

    This dissertation describes the syntheses of single-source molecular precursors to multi-component oxide materials. These molecules possess a core metal or element with various combinations of -OSi(O tBu)3, -O2P(OtBu) 2, and -OB[OSi(OtBu)3] 2 ligands. Such molecules decompose under mild thermolytic conditions (<200°C) to provide homogeneous carbon-free materials via the elimination of isobutylene and water. A gel is formed when thermolyses are performed in non-polar solvents, and subsequent drying of the gel in a conventional manner yields high surface area xerogels. This thermolytic molecular precursor (TMP) approach has been utilized to provide a variety of oxide materials with tailored properties. In addition, the oxygen rich environment of the molecular precursors coupled with the presence of M-O-E heterolinkages permits use of them as models for oxide-supported metal species and multi-component oxides. Significantly, the first complexes to contain three or more heteroelements suitable for use in the TMP method have been synthesized. Compounds for use as single-source molecular precursors have been synthesized containing Al, B, Cr, Hf, Mo, V, W, and Zr, and their thermal transformations have been examined. Heterogeneous catalytic reactions have been examined for selected materials. Also, cothermolyses of molecular precursors and additional molecules (i.e., metal alkoxides) have been utilized to provide materials with several components for potential use as catalysts or catalyst supports. Reactions of one and two equivs of HOSi(OtBu) 3 with Cr(OtBu)4 afforded the first Cr(IV) alkoxysiloxy complexes (tBuO) 3CrOSi(OtBu)3 and ( tBuO)2Cr[OSi(OtBu) 3]2, respectively. The high-yielding, convenient synthesis of (tBuO)3CrOSi(O tBu)3 make this complex a useful single-source molecular precursor, via the TMP method, to Cr/Si/O materials. The thermal transformations of (tBuO)3CrOSi(O tBu)3 and (tBuO) 2Cr[OSi(OtBu)3]2 to chromia-silica materials occurr at low temperatures

  20. Biosynthesis and characterization of silver nanoparticles prepared from two novel natural precursors by facile thermal decomposition methods

    NASA Astrophysics Data System (ADS)

    Goudarzi, Mojgan; Mir, Noshin; Mousavi-Kamazani, Mehdi; Bagheri, Samira; Salavati-Niasari, Masoud

    2016-09-01

    In this work, two natural sources, including pomegranate peel extract and cochineal dye were employed for the synthesis of silver nanoparticles. The natural silver complex from pomegranate peel extract resulted in nano-sized structures through solution-phase method, but this method was not efficient for cochineal dye-silver precursor and the as-formed products were highly agglomerated. Therefore, an alternative facile solid-state approach was investigated as for both natural precursors and the results showed successful production of well-dispersed nanoparticles with narrow size distribution for cochineal dye-silver precursor. The products were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy dispersive X-ray microanalysis (EDX), and Transmission Electron Microscopy (TEM).

  1. Preparation of Nano-sized Bismuth-Doped Fe3O4 as an Excellent Magnetic Material for Supercapacitor Electrodes

    NASA Astrophysics Data System (ADS)

    Aghazadeh, Mustafa; Karimzadeh, Isa; Ganjali, Mohammad Reza

    2018-03-01

    Nano-sized Bi3+-doped iron oxide (n-Bi-IO) particles were prepared through a one-pot electrochemical procedure, and the product was evaluated using x-ray diffraction, field-emission scanning electron microscopy and energy-dispersive x-ray spectroscopy. Based on the analyses, the average size of the n-Bi-IO was determined to be 10 nm. Galvanostatic charge-discharge (GCD) evaluations revealed that the specific capacitance of the material reached 235 F g-1 at a discharge condition of 0.2 A g-1. n-Bi-IO had a 94.2% capacity retention after 2000 GCD cycles. Further vibrating sample magnetometery analyses showed that the product has enhanced superparamagnetic qualities (i.e. M r = 0.15 emu g-1 and H Ci = 2.71 G) in comparison to iron oxide nanoparticles (i.e. M r = 0.95 emu g-1 and H Ci = 14.62 G). Given the results, the product is considered to be a promising material for developing high performance supercapacitor electrodes.

  2. Utilization of Mineral Wools as Alkali-Activated Material Precursor

    PubMed Central

    Yliniemi, Juho; Kinnunen, Paivo; Karinkanta, Pasi; Illikainen, Mirja

    2016-01-01

    Mineral wools are the most common insulation materials in buildings worldwide. However, mineral wool waste is often considered unrecyclable because of its fibrous nature and low density. In this paper, rock wool (RW) and glass wool (GW) were studied as alkali-activated material precursors without any additional co-binders. Both mineral wools were pulverized by a vibratory disc mill in order to remove the fibrous nature of the material. The pulverized mineral wools were then alkali-activated with a sodium aluminate solution. Compressive strengths of up to 30.0 MPa and 48.7 MPa were measured for RW and GW, respectively, with high flexural strengths measured for both (20.1 MPa for RW and 13.2 MPa for GW). The resulting alkali-activated matrix was a composite-type in which partly-dissolved fibers were dispersed. In addition to the amorphous material, sodium aluminate silicate hydroxide hydrate and magnesium aluminum hydroxide carbonate phases were identified in the alkali-activated RW samples. The only crystalline phase in the GW samples was sodium aluminum silicate. The results of this study show that mineral wool is a very promising raw material for alkali activation. PMID:28773435

  3. Copper-containing ceramic precursor synthesis: Solid-state transformations and materials technology

    NASA Technical Reports Server (NTRS)

    Hepp, Aloysius F.; Eckles, William E.; Duraj, Stan A.; Andras, Maria T.; Fanwick, Phillip E.; Richman, Robert M.; Sabat, Michael L.; Power, Michael B.; Gordon, Edward M.; Barron, Andrew

    1994-01-01

    Three copper systems with relevance to materials technology are discussed. In the first, a CuS precursor, Cu4S1O (4-methylpyridine)(sub 4)- (4-MePy), was prepared by three routes: reaction of Cu2S, reaction of CuBr-SMe2, and oxidation of copper powder with excess sulfur in 4-methylpyridine by sulfur. In the second, copper powder was found to react with excess thiourea (H2NC(S)NH2) in 4-methylpyridine to produce thiocyanate (NCS(-)) complexes. Three isolated and characterized compounds are: Cu(NCS)(4-MePy)(sub 2), a polymer, (4-MePy-H)(Cu(NCS)(sub 3)(4-MePy)(sub 2)), a salt, and t-Cu(NCS)(sub 2)(4-MePy)(sub 4). Finally, an attempt to produce a mixed-metal sulfide precursor of Cu and Ga in N-methylimidazole (N-MeIm) resulted in the synthesis of a Cu-containing polymer, Cu(SO4)(N-MeIm). The structures are presented; the chemistry will be briefly discussed in the context of preparation and processing of copper-containing materials for aerospace applications.

  4. Influence of calcium precursors on the morphology and crystallinity of sol gel-derived hydroxyapatite nanoparticles

    NASA Astrophysics Data System (ADS)

    Vijayalakshmi Natarajan, U.; Rajeswari, S.

    2008-10-01

    Nanosized hydroxyapatite (HAP) particles were prepared by sol-gel method from the water-based solution of calcium and phosphorus precursor. In this study, two calcium precursors such as calcium nitrate tetrahydrate and calcium acetate were chosen as calcium precursors. The influence of aging period, pH, viscosity and sintering temperature on crystallinity and morphology of the HAP particles were investigated for the two calcium precursors with triethyl phosphate precursor. The morphology of nano-HAP towards phosphorous precursor was dependent on the type of calcium precursor used. The HAP prepared from calcium nitrate and triethyl phosphate was spherically shaped whereas the one from calcium acetate was found to be fibrous in structure. Both HAPs were stable up to 1200 °C and their crystallinity increased with respect to the sintering temperature. The obtained sample was characterized through X-ray diffraction (XRD), P 31 nuclear magnetic resonance (NMR), scanning electronic microscopy (SEM) and TEM analysis. The sol derived from the optimized aging period for the two different calcium precursors was coated on 316L stainless-steel (SS) implant and its corrosion resistivity during long-term implantation was studied by cyclic polarization in Ringer's solution. Both HAPs have their own desirable qualities and were found to be corrosion resistive.

  5. A novel copper (II) complex containing a tetradentate Schiff base: Synthesis, spectroscopy, crystal structure, DFT study, biological activity and preparation of its nano-sized metal oxide

    NASA Astrophysics Data System (ADS)

    Tohidiyan, Zeinab; Sheikhshoaie, Iran; Khaleghi, Mouj; Mague, Joel T.

    2017-04-01

    A new nano-sized copper (II) complex, [Cu(L)] with a tetra dentate Schiff base ligand, 2-((E)-(2-(E-5- bromo-2-hydroxybezenylideneamino) methyl)-4-bromophenol [H2L] was prepared by the reaction between of Cu (CH3COO)2·2H2O and (H2L) ligand with the ratio of 1:1, at the present of triethylamine by sonochemical method. The structure of [Cu (L)] complex was determined by FT-IR, UV-Vis, FESEM and molar conductivity. The structure of [Cu (L)] complex was characterized by single crystal X-ray diffraction. The geometry of [Cu (L)] complex was optimized using density functional theory (DFT) method with the B3LYP/6-31(d) level of theory. The calculated bond lengths and bond angles are in good agreement with the X-ray data. This complex was used as a novel precursor for preparing of CuO nano particles by the thermal decomposition method. The antibacterial activities of [H2L] ligand, nano-sized [Cu (L)] complex and nano-sized CuO have been screened against various strains of bacteria. According to the results, nano-sized CuO can be considered as an appropriate antibiotic agent.

  6. Material nanosizing effect on living organisms: non-specific, biointeractive, physical size effects

    PubMed Central

    Watari, Fumio; Takashi, Noriyuki; Yokoyama, Atsuro; Uo, Motohiro; Akasaka, Tsukasa; Sato, Yoshinori; Abe, Shigeaki; Totsuka, Yasunori; Tohji, Kazuyuki

    2009-01-01

    Nanosizing effects of materials on biological organisms was investigated by biochemical cell functional tests, cell proliferation and animal implantation testing. The increase in specific surface area causes the enhancement of ionic dissolution and serious toxicity for soluble, stimulative materials. This effect originates solely from materials and enhances the same functions as those in a macroscopic size as a catalyst. There are other effects that become prominent, especially for non-soluble, biocompatible materials such as Ti. Particle size dependence showed the critical size for the transition of behaviour is at approximately 100 μm, 10 μm and 200 nm. This effect has its origin in the biological interaction process between both particles and cells/tissue. Expression of superoxide anions, cytokines tumour necrosis factor-α and interleukin-1β from neutrophils was increased with the decrease in particle size and especially pronounced below 10 μm, inducing phagocytosis to cells and inflammation of tissue, although inductively coupled plasma chemical analysis showed no dissolution from Ti particles. Below 200 nm, stimulus decreases, then particles invade into the internal body through the respiratory or digestive systems and diffuse inside the body. Although macroscopic hydroxyapatite, which exhibits excellent osteoconductivity, is not replaced with natural bone, nanoapatite composites induce both phagocytosis of composites by osteoclasts and new bone formation by osteoblasts when implanted in bone defects. The progress of this bioreaction results in the conversion of functions to bone substitution. Although macroscopic graphite is non-cell adhesive, carbon nanotubes (CNTs) are cell adhesive. The adsorption of proteins and nano-meshwork structure contribute to the excellent cell adhesion and growth on CNTs. Non-actuation of the immune system except for a few innate immunity processes gives the non-specific nature to the particle bioreaction and

  7. Elemental selenium particles at nano-size (Nano-Se) are more toxic to Medaka (Oryzias latipes) as a consequence of hyper-accumulation of selenium: a comparison with sodium selenite.

    PubMed

    Li, Hongcheng; Zhang, Jinsong; Wang, Thanh; Luo, Wenru; Zhou, Qunfang; Jiang, Guibin

    2008-09-29

    Recent studies have shown that elemental selenium particles at nano-size (Nano-Se) exhibited comparable bioavailability and less toxicity in mice and rats when compared to sodium selenite, selenomethinine and methylselenocysteine. However, little is known about the toxicity profile of Nano-Se in aquatic animals. In the present study, toxicities of Nano-Se and selenite in selenium-sufficient Medaka fish were compared. Selenium bioaccumulation and subsequent clearance in fish livers, gills, muscles and whole bodies were examined after 10 days of exposure to Nano-Se and selenite (100 microg Se/L) and again after 7 days of depuration. Both forms of selenium exposure effectively increased selenium concentrations in the investigated tissues. Surprisingly, Nano-Se was found to be more hyper-accumulated in the liver compared to selenite with differences as high as sixfold. Selenium clearance of both Nano-Se and selenite occurred at similar ratios in whole bodies and muscles but was not rapidly cleared from livers and gills. Nano-Se exhibited strong toxicity for Medaka with an approximately fivefold difference in terms of LC(50) compared to selenite. Nano-Se also caused larger effects on oxidative stress, most likely due to more hyper-accumulation of selenium in liver. The present study suggests that toxicity of nanoparticles can largely vary between different species and concludes that the evaluation of nanotoxicology should be carried out on a case-by-case basis.

  8. Design and synthesis of polyoxometalate-framework materials from cluster precursors

    NASA Astrophysics Data System (ADS)

    Vilà-Nadal, Laia; Cronin, Leroy

    2017-10-01

    Inorganic oxide materials are used in semiconductor electronics, ion exchange, catalysis, coatings, gas sensors and as separation materials. Although their synthesis is well understood, the scope for new materials is reduced because of the stability limits imposed by high-temperature processing and top-down synthetic approaches. In this Review, we describe the derivatization of polyoxometalate (POM) clusters, which enables their assembly into a range of frameworks by use of organic or inorganic linkers. Additionally, bottom-up synthetic approaches can be used to make metal oxide framework materials, and the features of the molecular POM precursors are retained in these structures. Highly robust all-inorganic frameworks can be made using metal-ion linkers, which combine molecular synthetic control without the need for organic components. The resulting frameworks have high stability, and high catalytic, photochemical and electrochemical activity. Conceptually, these inorganic oxide materials bridge the gap between zeolites and metal-organic frameworks (MOFs) and establish a new class of all-inorganic POM frameworks that can be designed using topological and reactivity principles similar to MOFs.

  9. Advanced transition metal phosphide materials from single-source molecular precursors

    NASA Astrophysics Data System (ADS)

    Colson, Adam Caleb

    In this thesis, the feasibility of employing organometallic single-source precursors in the preparation of advanced transition metal pnictide materials such as colloidal nanoparticles and films has been investigated. In particular, the ternary FeMnP phase was targeted as a model for preparing advanced heterobimetallic phosphide materials, and the iron-rich Fe3P phase was targeted due to its favorable ferromagnetic properties as well as the fact that the preparation of advanced Fe3P materials has been elusive by commonly used methods. Progress towards the synthesis of advanced Fe2--xMn xP nanomaterials and films was facilitated by the synthesis of the novel heterobimetallic complexes FeMn(CO)8(mu-PR1R 2) (R1 = H, R2 = H or R1 = H, R2 = Ph), which contain the relatively rare mu-PH2 and mu-PPhH functionalities. Iron rich Fe2--xMnxP nanoparticles were obtained by thermal decomposition of FeMn(CO)8(mu-PH 2) using solution-based synthetic methods, and empirical evidence suggested that oleic acid was responsible for manganese depletion. Films containing Fe, Mn, and P with the desired stoichiometric ratio of 1:1:1 were prepared using FeMn(CO)8(mu-PH2) in a simple low-pressure metal-organic chemical vapor deposition (MOCVD) apparatus. Although the elemental composition of the precursor was conserved in the deposited film material, spectroscopic evidence indicated that the films were not composed of pure-phase FeMnP, but were actually mixtures of crystalline FeMnP and amorphous FeP and Mn xOy. A new method for the preparation of phase-pure ferromagnetic Fe 3P films on quartz substrates has also been developed. This approach involved the thermal decomposition of the single-source precursors H 2Fe3(CO)9PR (R = tBu or Ph) at 400 °C. The films were deposited using a simple home-built MOCVD apparatus and were characterized using a variety of analytical methods. The films exhibited excellent phase purity, as evidenced by X-ray diffraction, X-ray photoelectron spectroscopy, and

  10. Effects of nanosized constriction on thermal transport properties of graphene

    PubMed Central

    2014-01-01

    Thermal transport properties of graphene with nanosized constrictions are investigated using nonequilibrium molecular dynamics simulations. The results show that the nanosized constrictions have a significant influence on the thermal transport properties of graphene. The thermal resistance of the nanosized constrictions is on the order of 107 to 109 K/W at 150 K, which reduces the thermal conductivity by 7.7% to 90.4%. It is also found that the constriction resistance is inversely proportional to the width of the constriction and independent of the heat current. Moreover, we developed an analytical model for the ballistic thermal resistance of the nanosized constrictions in two-dimensional nanosystems. The theoretical prediction agrees well with the simulation results in this paper, which suggests that the thermal transport across the nanosized constrictions in two-dimensional nanosystems is ballistic in nature. PACS 65.80.CK; 61.48.Gh; 63.20.kp; 31.15.xv PMID:25232292

  11. Origin of Capacity Fading in Nano-Sized Co3O4 Electrodes: Electrochemical Impedance Spectroscopy Study

    NASA Astrophysics Data System (ADS)

    Kang, Jin-Gu; Ko, Young-Dae; Park, Jae-Gwan; Kim, Dong-Wan

    2008-10-01

    Transition metal oxides have been suggested as innovative, high-energy electrode materials for lithium-ion batteries because their electrochemical conversion reactions can transfer two to six electrons. However, nano-sized transition metal oxides, especially Co3O4, exhibit drastic capacity decay during discharge/charge cycling, which hinders their practical use in lithium-ion batteries. Herein, we prepared nano-sized Co3O4 with high crystallinity using a simple citrate-gel method and used electrochemical impedance spectroscopy method to examine the origin for the drastic capacity fading observed in the nano-sized Co3O4 anode system. During cycling, AC impedance responses were collected at the first discharged state and at every subsequent tenth discharged state until the 100th cycle. By examining the separable relaxation time of each electrochemical reaction and the goodness-of-fit results, a direct relation between the charge transfer process and cycling performance was clearly observed.

  12. Materials Design Through Chemical Control of Precursors

    DTIC Science & Technology

    2008-08-22

    Ligand Sets,” H. M. El-Kaderi, M.J. Heeg, and C.H. Winter, Polyhedron 2006, 25, 224-234. 7. “Atomic Layer Deposition of Ga2O3 Films from a...poster presentation. 4. “Atomic Layer Deposition (ALD) of High Quality Ga2O3 Thin Films from a Dimeric Dialkylamido-Bridged Gallium Complex,” C. L...growth of Ga2O3 films from a new metalorganic precursor (“Atomic Layer Deposition of Ga2O3 Films from a 4 Dialkylamido-Based Precursor,” C. L

  13. From iron(III) precursor to magnetite and vice versa

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gotic, M., E-mail: gotic@irb.hr; Jurkin, T.; Music, S.

    2009-10-15

    The syntheses of nanosize magnetite particles by wet-chemical oxidation of Fe{sup 2+} have been extensively investigated. In the present investigation the nanosize magnetite particles were synthesised without using the Fe(II) precursor. This was achieved by {gamma}-irradiation of water-in-oil microemulsion containing only the Fe(III) precursor. The corresponding phase transformations were monitored. Microemulsions (pH {approx} 12.5) were {gamma}-irradiated at a relatively high dose rate of {approx}22 kGy/h. Upon 1 h of {gamma}-irradiation the XRD pattern of the precipitate showed goethite and unidentified low-intensity peaks. Upon 6 h of {gamma}-irradiation, reductive conditions were achieved and substoichiometric magnetite ({approx}Fe{sub 2.71}O{sub 4}) particles with insignificantmore » amount of goethite particles found in the precipitate. Hydrated electrons (e{sub aq}{sup -}), organic radicals and hydrogen gas as radiolytic products were responsible for the reductive dissolution of iron oxide in the microemulsion and the reduction Fe{sup 3+} {yields} Fe{sup 2+}. Upon 18 h of {gamma}-irradiation the precipitate exhibited dual behaviour, it was a more oxidised product than the precipitate obtained after 6 h of {gamma}-irradiation, but it contained magnetite particles in a more reduced form ({approx}Fe{sub 2.93}O{sub 4}). It was presumed that the reduction and oxidation processes existed as concurrent competitive processes in the microemulsion. After 18 h of {gamma}-irradiation the pH of the medium shifted from the alkaline to the acidic range. The high dose rate of {approx}22 kGy/h was directly responsible for this shift to the acidic range. At a slightly acidic pH a further reduction of Fe{sup 3+} {yields} Fe{sup 2+} resulted in the formation of more stoichiometric magnetite particles, whereas the oxidation conditions in the acidic medium permitted the oxidation Fe{sup 2+} {yields} Fe{sup 3+}. The Fe{sup 3+} was much less soluble in the acidic medium and it

  14. Low Velocity Detonation of Nitromethane Affected by Precursor Shock Waves Propagating in Various Container Materials

    NASA Astrophysics Data System (ADS)

    Hamashima, H.; Osada, A.; Itoh, S.; Kato, Y.

    2007-12-01

    It is well known that some liquid explosives have two detonation behaviors, high velocity detonation (HVD) or low velocity detonation (LVD) can propagate. A physical model to describe the propagation mechanism of LVD in liquid explosives was proposed that LVD is not a self-reactive detonation, but rather a supported-reactive detonation from the cavitation field generated by precursor shock waves. However, the detailed structure of LVD in liquid explosives has not yet been clarified. In this study, high-speed photography was used to investigate the effects of the precursor shock waves propagating in various container materials for LVD in nitromethane (NM). Stable LVD was not observed in all containers, although transient LVD was observed. A very complicated structure of LVD was observed: the interaction of multiple precursor shock waves, multiple oblique shock waves, and the cavitation field.

  15. Low Velocity Detonation of Nitromethane Affected by Precursor Shock Waves Propagating in Various Container Materials

    NASA Astrophysics Data System (ADS)

    Hamashima, Hideki; Osada, Akinori; Kato, Yukio; Itoh, Shigeru

    2007-06-01

    It is well known that some liquid explosives have two detonation behaviors, high velocity detonation (HVD) or low velocity detonation (LVD) can propagate. A physical model to describe the propagation mechanism of LVD in liquid explosives was proposed that LVD is not a self-reactive detonation, but rather a supported-reactive detonation from the cavitation field generated by precursor shock waves. However, the detailed structure of LVD in liquid explosives has not yet been clarified. In this study, high-speed photography was used to investigate the effects of the precursor shock waves propagating in various container materials for LVD in nitromethane (NM). Stable LVD was not observed in all containers, although transient LVD was observed. A very complicated structure of LVD was observed: the interaction of multiple precursor shock waves, multiple oblique shock waves, and the cavitation field.

  16. Insulating Materials Comprising Polysilazane, Methods of Forming Such Insulating Materials, and Precursor Formulations Comprising Polysilazane

    NASA Technical Reports Server (NTRS)

    Larson, Robert S. (Inventor); Fuller, Michael E. (Inventor)

    2013-01-01

    Methods of forming an insulating material comprising combining a polysilazane, a cross-linking compound, and a gas-generating compound to form a reaction mixture, and curing the reaction mixture to form a modified polysilazane. The gas-generating compound may be water, an alcohol, an amine, or combinations thereof. The cross-linking compound may be an isocyanate, an epoxy resin, or combinations thereof. The insulating material may include a matrix comprising one of a reaction product of a polysilazane and an isocyanate and a reaction product of a polysilazane and an epoxy resin. The matrix also comprises a plurality of interconnected pores produced from one of reaction of the polysilazane and the isocyanate and from reaction of the polysilazane and the epoxy resin. A precursor formulation that comprises a polysilazane, a cross-linking compound, and a gas-generating compound is also disclosed.

  17. Recent advances in nanosized Mn-Zn ferrite magnetic fluid hyperthermia for cancer treatment.

    PubMed

    Lin, Mei; Huang, Junxing; Sha, Min

    2014-01-01

    This paper reviews the recent research and development of nanosized manganese zinc (Mn-Zn) ferrite magnetic fluid hyperthermia (MFH) for cancer treatment. Mn-Zn ferrite MFH, which has a targeted positioning function that only the temperature of tumor tissue with magnetic nanoparticles can rise, while normal tissue without magnetic nanoparticles is not subject to thermal damage, is a promising therapy for cancer. We introduce briefly the composition and properties of magnetic fluid, the concept of MFH, and features of Mn-Zn ferrite magnetic nanoparticles for MFH such as thermal bystander effect, universality, high specific absorption rate, the targeting effect of small size, uniformity of hyperthermia temperature, and automatic temperature control and constant temperature effect. Next, preparation methods of Mn-Zn ferrite magnetic fluid are discussed, and biocompatibility and biosecurity of Mn-Zn ferrite magnetic fluid are analyzed. Then the applications of nanosized Mn-Zn ferrite MFH in cancer are highlighted, including nanosized Mn-Zn ferrite MFH alone, nanosized Mn-Zn ferrite MFH combined with As2O3 chemotherapy, and nanosized Mn-Zn ferrite MFH combined with radiotherapy. Finally, the combination application of nanosized Mn-Zn ferrite MFH and gene-therapy is conceived, and the challenges and perspectives for the future of nanosized Mn-Zn ferrite MFH for oncotherapy are discussed.

  18. Activated microporous materials through polymerization of microemulsion precursors

    NASA Astrophysics Data System (ADS)

    Venkatesan, Arunkumar

    Microemulsions have been well studied for their unique characteristics. They are isotropic, thermodynamically stable and microstructured mixtures of oil and water stabilized by one or more surfactant species. They are formed spontaneously and are thermodynamically stable. Microemulsion precursors can be polymerized to make microporous solids with controlled pore structure and sizes. These polymeric solids have been studied extensively in the past. Although the fundamental properties of the microporous solids have been studied in depth, the development of specific applications that will utilize the unique properties of these solids has not been exhaustively researched. The current work establishes the feasibility of making activated microporous solids from microemulsion precursors, by the use of a ligand that chelates metals and also attaches itself to the polymer monolith. It also uses a novel 'in-situ' incorporation by combining the formulation and incorporation steps into one. The research objectives are, to formulate a microemulsion system that can yield useful microporous solids upon polymerization and activation, to characterize these solids using existing techniques available for analysis of similar microporous solids, to identify and understand the effect of the variables in the system and to study the influence of these variables on the performance characteristics of this material. Characterization techniques like Differential Scanning Calorimetry, Thermogravimetric Analysis and Scanning Electron Microscopy were used. A hydroxyethylmethylmethacrylate/methylmethacrylate/aqueous phase containing 10% SDS' system was chosen as the precursor microemulsion and the corresponding microporous solids were made. A metal chelating ligand, Congo Red, was incorporated onto the microporous polymer using NaOH as a binding agent. The ability of the resultant 'activated' microporous solid to remove metal ions from solution, was evaluated. The metal ion chosen was chromium

  19. Hydridosiloxanes as precursors to ceramic products

    DOEpatents

    Blum, Yigal D.; Johnson, Sylvia M.; Gusman, Michael I.

    1997-01-01

    A method is provided for preparing ceramic precursors from hydridosiloxane starting materials and then pyrolyzing these precursors to give rise to silicious ceramic materials. Si--H bonds present in the hydridosiloxane starting materials are catalytically activated, and the activated hydrogen atoms may then be replaced with nonhydrogen substituents. These preceramic materials are pyrolyzed in a selected atmosphere to give the desired ceramic product. Ceramic products which may be prepared by this technique include silica, silicon oxynitride, silicon carbide, metal silicates, and mullite.

  20. Hydridosiloxanes as precursors to ceramic products

    DOEpatents

    Blum, Y.D.; Johnson, S.M.; Gusman, M.I.

    1997-06-03

    A method is provided for preparing ceramic precursors from hydridosiloxane starting materials and then pyrolyzing these precursors to give rise to silicious ceramic materials. Si-H bonds present in the hydridosiloxane starting materials are catalytically activated, and the activated hydrogen atoms may then be replaced with nonhydrogen substituents. These preceramic materials are pyrolyzed in a selected atmosphere to give the desired ceramic product. Ceramic products which may be prepared by this technique include silica, silicon oxynitride, silicon carbide, metal silicates, and mullite.

  1. Metabolic Engineering of Plants to Produce Precursors (Phloroglucinol and 1,2,4-butanetriol) of Energetic Materials

    DTIC Science & Technology

    2015-01-02

    phloroglucinol, which are precursors of energetic materials butanetriol trinitrate (BTTN) and l ,3,5-triamino-2,4,6 trinitrobenzene (TATB), respectively, in...of energetic materials butanetriol trinitrate (BTTN) and l ,3,5-triamino-2,4,6 trinitrobenzene (TATB), respectively, in plants. The strategy was to... phenylalanine , valine and hexose sugars. On the other hand the metabolites that are completely depleted in the chloroplastic lines and partially in

  2. Bacterial Cellular Materials as Precursors of Chloroform

    NASA Astrophysics Data System (ADS)

    Wang, J.; Ng, T.; Zhang, Q.; Chow, A. T.; Wong, P.

    2011-12-01

    The environmental sources of chloroform and other halocarbons have been intensively investigated because their effects of stratospheric ozone destruction and environmental toxicity. It has been demonstrated that microorganisms could facilitate the biotic generation of chloroform from natural organic matters in soil, but whether the cellular materials itself also serves as an important precursor due to photo-disinfection is poorly known. Herein, seven common pure bacterial cultures (Acinetobacter junii, Aeromonas hydrophila, Bacillus cereus, Bacillus substilis, Escherichia coli, Shigella sonnei, Staphylococcus sciuri) were chlorinated to evaluate the yields of chloroform, dibromochloromethane, dichlorobromomethane, and bromoform. The effects of bromide on these chemical productions and speciations were also investigated. Results showed that, on average, 5.64-36.42 μg-chloroform /mg-C were generated during the bacterial chlorination, in similar order of magnitude to that generated by humic acid (previously reported as 78 μg-chloroform/mg-C). However, unlike humic acid in water chlorination, chloroform concentration did not simply increase with the total organic carbon in water mixture. In the presence of bromide, the yield of brominated species responded linearly to the bromide concentration. This study provides useful information to understand the contributions of chloroform from photodisinfection processes in coastal environments.

  3. Thermal Stress Behavior of Micro- and Nano-Size Aluminum Films

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hanabusa, T.; Kusaka, K.; Nishida, M.

    2008-03-17

    In-situ observation of thermal stresses in thin films deposited on silicon substrate was made by X-ray and synchrotron radiation. Specimens prepared in this experiment were micro- and nano-size thin aluminum films with and without passivation film. The thickness of the film was 1 micrometer for micro-size films and 10, 20 and 50 nanometer for nano-size films. The stress measurement in micro-size films was made by X-ray radiation whereas the measurement of nano-size films was made by synchrotron radiation. Residual stress measurement revealed tensile stresses in all as-deposited films. Thermal stresses were measured in a series of heating- and cooling-stage. Thermalmore » stress behavior of micro-size films revealed hysteresis loop during a heating and cooling process. The width of a hysteresis loop was larger in passivated film that unpassivated film. No hysteresis loops were observed in nano-size films with SiO{sub 2} passivation. Strengthning mechanism in thin films was discussed on a passivation film and a film thickness.« less

  4. Methods for forming particles from single source precursors

    DOEpatents

    Fox, Robert V [Idaho Falls, ID; Rodriguez, Rene G [Pocatello, ID; Pak, Joshua [Pocatello, ID

    2011-08-23

    Single source precursors are subjected to carbon dioxide to form particles of material. The carbon dioxide may be in a supercritical state. Single source precursors also may be subjected to supercritical fluids other than supercritical carbon dioxide to form particles of material. The methods may be used to form nanoparticles. In some embodiments, the methods are used to form chalcopyrite materials. Devices such as, for example, semiconductor devices may be fabricated that include such particles. Methods of forming semiconductor devices include subjecting single source precursors to carbon dioxide to form particles of semiconductor material, and establishing electrical contact between the particles and an electrode.

  5. Nano-Se Assimilation and Action in Poultry and Other Monogastric Animals: Is Gut Microbiota an Answer?

    NASA Astrophysics Data System (ADS)

    Surai, Peter F.; Kochish, Ivan I.; Velichko, Oksana A.

    2017-12-01

    Recently, a comprehensive review paper devoted to roles of nano-Se in livestock and fish nutrition has been published in the Nanoscale Research Letters. The authors described in great details an issue related to nano-Se production and its possible applications in animal industry and medicine. However, molecular mechanisms of nano-Se action were not described and the question of how nano-Se is converted into active selenoproteins is not resolved. It seems likely that the gut microbiota can convert nano-Se into selenite, H2Se or Se-phosphate with the following synthesis of selenoproteins. This possibility needs to be further studied in detail, and advantages and disadvantages of nano-Se as a source of Se in animal/poultry/fish nutrition await critical evaluations.

  6. Modeling Initial Stage of Ablation Material Pyrolysis: Graphitic Precursor Formation and Interfacial Effects

    NASA Technical Reports Server (NTRS)

    Desai, Tapan G.; Lawson, John W.; Keblinski, Pawel

    2010-01-01

    Reactive molecular dynamics simulations are used to study initial stage of pyrolysis of ablation materials and their composites with carbon nanotubes and carbon fibers. The products formed during pyrolysis are characterized and water is found as the primary product in all cases. The water formation mechanisms are analyzed and the value of the activation energy for water formation is estimated. A detailed study on graphitic precursor formation reveals the presence of two temperature zones. In the lower temperature zone (less than 2000 K) polymerization occurs resulting in formation of large, stable graphitic precursors, and in the high temperature zone (greater than 2000 K) polymer scission results in formation of short polymer chains/molecules. Simulations performed in the high temperature zone on the phenolic resin composites (with carbon nanotubes and carbon fibers) shows that the presence of interfaces had no substantial effect on the chain scission rate or the activation energy value for water formation.

  7. Improvement of the tool life of a micro-end mill using nano-sized SiC/Ni electroplating method.

    PubMed

    Park, Shinyoung; Kim, Kwang-Su; Roh, Ji Young; Jang, Gyu-Beom; Ahn, Sung-Hoon; Lee, Caroline Sunyong

    2012-04-01

    High mechanical properties of a tungsten carbide micro-end-mill tool was achieved by extending its tool life by electroplating nano-sized SiC particles (< 100 nm) that had a hardness similar to diamond in a nickel-based material. The co-electroplating method on the surface of the micro-end-mill tool was applied using SiC particles and Ni particles. Organic additives (saccharin and ammonium chloride) were added in a Watts bath to improve the nickel matrix density in the electroplating bath and to smooth the surface of the co-electroplating. The morphology of the coated nano-sized SiC particles and the composition were measured using Scanning Electron Microscope and Energy Dispersive Spectrometer. As the Ni/SiC co-electroplating layer was applied, the hardness and friction coefficient improved by 50%. Nano-sized SiC particles with 7 wt% were deposited on the surface of the micro-end mill while the Ni matrix was smoothed by adding organic additives. The tool life of the Ni/SiC co-electroplating coating on the micro-end mill was at least 25% longer than that of the existing micro-end mills without Ni/SiC co-electroplating. Thus, nano-sized SiC/Ni coating by electroplating significantly improves the mechanical properties of tungsten carbide micro-end mills.

  8. Nanosizing and nanoconfinement: new strategies towards meeting hydrogen storage goals.

    PubMed

    de Jongh, Petra E; Adelhelm, Philipp

    2010-12-17

    Hydrogen is expected to play an important role as an energy carrier in a future, more sustainable society. However, its compact, efficient, and safe storage is an unresolved issue. One of the main options is solid-state storage in hydrides. Unfortunately, no binary metal hydride satisfies all requirements regarding storage density and hydrogen release and uptake. Increasingly complex hydride systems are investigated, but high thermodynamic stabilities as well as slow kinetics and poor reversibility are important barriers for practical application. Nanostructuring by ball-milling is an established method to reduce crystallite sizes and increase reaction rates. Since five years attention has also turned to alternative preparation techniques that enable particle sizes below 10 nanometers and are often used in conjunction with porous supports or scaffolds. In this Review we discuss the large impact of nanosizing and -confinement on the hydrogen sorption properties of metal hydrides. We illustrate possible preparation strategies, provide insight into the reasons for changes in kinetics, reversibility and thermodynamics, and highlight important progress in this field. All in all we provide the reader with a clear view of how nanosizing and -confinement can beneficially affect the hydrogen sorption properties of the most prominent materials that are currently considered for solid-state hydrogen storage.

  9. A versatile single molecular precursor for the synthesis of layered oxide cathode materials for Li-ion batteries.

    PubMed

    Li, Maofan; Liu, Jiajie; Liu, Tongchao; Zhang, Mingjian; Pan, Feng

    2018-02-01

    A carbonyl-bridged single molecular precursor LiTM(acac) 3 [transition metal (TM) = cobalt/manganese/nickel (Co/Mn/Ni), acac = acetylacetone], featuring a one-dimensional chain structure, was designed and applied to achieve the layered oxide cathode materials: LiTMO 2 (TM = Ni/Mn/Co, NMC). As examples, layered oxides, primary LiCoO 2 , binary LiNi 0.8 Co 0.2 O 2 and ternary LiNi 0.5 Mn 0.3 Co 0.2 O 2 were successfully prepared to be used as cathode materials. When they are applied to lithium-ion batteries (LIBs), all exhibit good electrochemical performance because of their unique morphology and great uniformity of element distribution. This versatile precursor is predicted to accommodate many other metal cations, such as aluminum (Al 3+ ), iron (Fe 2+ ), and sodium (Na + ), because of the flexibility of organic ligand, which not only facilitates the doping-modification of the NMC system, but also enables synthesis of Na-ion layered oxides. This opens a new direction of research for the synthesis of high-performance layered oxide cathode materials for LIBs.

  10. Synthesis, characterization, microstructure, optical and magnetic properties of strontium cobalt carbonate precursor and Sr2Co2O5 oxide material

    NASA Astrophysics Data System (ADS)

    Agilandeswari, K.; Ruban Kumar, A.

    2014-04-01

    Sr2Co2O5 ceramic synthesized by the coprecipitation of strontium cobalt carbonate method. XRD analysis shows the single phase strontianite precursor and decomposed oxide product as orthorhombic structure of Sr2Co2O5. Thermal analysis proves the Sr2Co2O5 phase formation temperature of 800 °C. SEM image indicates crystalline rod shaped carbonate precursor transformed to oxide as porous diffused sphere shape particles. Optical band gap it reveals the strontium cobalt carbonate precursor as insulating material and the Sr2Co2O5 as semiconducting nature. The room temperature magnetic study indicates the carbonate precursor as paramagnetic but its oxide Sr2Co2O5 as superparamagnetic behavior.

  11. Multiscale analysis: a way to investigate laser damage precursors in materials for high power applications at nanosecond pulse duration

    NASA Astrophysics Data System (ADS)

    Natoli, J. Y.; Wagner, F.; Ciapponi, A.; Capoulade, J.; Gallais, L.; Commandré, M.

    2010-11-01

    The mechanism of laser induced damage in optical materials under high power nanosecond laser irradiation is commonly attributed to the presence of precursor centers. Depending on material and laser source, the precursors could have different origins. Some of them are clearly extrinsic, such as impurities or structural defects linked to the fabrication conditions. In most cases the center size ranging from sub-micrometer to nanometer scale does not permit an easy detection by optical techniques before irradiation. Most often, only a post mortem observation of optics permits to proof the local origin of breakdown. Multi-scale analyzes by changing irradiation beam size have been performed to investigate the density, size and nature of laser damage precursors. Destructive methods such as raster scan, laser damage probability plot and morphology studies permit to deduce the precursor densities. Another experimental way to get information on nature of precursors is to use non destructive methods such as photoluminescence and absorption measurements. The destructive and non destructive multiscale studies are also motivated for practical reasons. Indeed LIDT studies of large optics as those used in LMJ or NIF projects are commonly performed on small samples and with table top lasers whose characteristics change from one to another. In these conditions, it is necessary to know exactly the influence of the different experimental parameters and overall the spot size effect on the final data. In this paper, we present recent developments in multiscale characterization and results obtained on optical coatings (surface case) and KDP crystal (bulk case).

  12. Uniform nanoparticles by flame-assisted spray pyrolysis (FASP) of low cost precursors

    PubMed Central

    Rudin, Thomas; Wegner, Karsten

    2013-01-01

    A new flame-assisted spray pyrolysis (FASP) reactor design is presented, which allows the use of inexpensive precursors and solvents (e.g., ethanol) for synthesis of nanoparticles (10–20 nm) with uniform characteristics. In this reactor design, a gas-assisted atomizer generates the precursor solution spray that is mixed and combusted with externally fed inexpensive fuel gases (acetylene or methane) at a defined height above the atomizing nozzle. The gaseous fuel feed can be varied to control the combustion enthalpy content of the flame and onset of particle formation. This way, the enthalpy density of the flame is decoupled from the precursor solution composition. Low enthalpy content precursor solutions are prone to synthesis of non-uniform particles (e.g., bimodal particle size distribution) by standard flame spray pyrolysis (FSP) processes. For example, metal nitrates in ethanol typically produce nanosized particles by gas-to-particle conversion along with larger particles by droplet-to-particle conversion. The present FASP design facilitates the use of such low enthalpy precursor solutions for synthesis of homogeneous nanopowders by increasing the combustion enthalpy density of the flame with low-cost, gaseous fuels. The effect of flame enthalpy density on product properties in the FASP configuration is explored by the example of Bi2O3 nanoparticles produced from bismuth nitrate in ethanol. Product powders were characterized by nitrogen adsorption, X-ray diffraction, X-ray disk centrifuge, and transmission electron microscopy. Homogeneous Bi2O3 nanopowders were produced both by increasing the gaseous fuel content and, most notably, by cutting the air entrainment prior to ignition of the spray. PMID:23408113

  13. Synthesis and Reaction Chemistry of Nanosize Monosodium Titanate

    PubMed Central

    Elvington, Mark C.; Taylor-Pashow, Kathryn M. L.; Tosten, Michael H.; Hobbs, David T.

    2016-01-01

    This paper describes the synthesis and peroxide-modification of nanosize monosodium titanate (nMST), along with an ion-exchange reaction to load the material with Au(III) ions. The synthesis method was derived from a sol-gel process used to produce micron-sized monosodium titanate (MST), with several key modifications, including altering reagent concentrations, omitting a particle seed step, and introducing a non-ionic surfactant to facilitate control of particle formation and growth. The resultant nMST material exhibits spherical-shaped particle morphology with a monodisperse distribution of particle diameters in the range from 100 to 150 nm. The nMST material was found to have a Brunauer-Emmett-Teller (BET) surface area of 285 m2g-1, which is more than an order of magnitude higher than the micron-sized MST. The isoelectric point of the nMST measured 3.34 pH units, which is a pH unit lower than that measured for the micron-size MST. The nMST material was found to serve as an effective ion exchanger under weakly acidic conditions for the preparation of an Au(III)-exchange nanotitanate. In addition, the formation of the corresponding peroxotitanate was demonstrated by reaction of the nMST with hydrogen peroxide. PMID:26967828

  14. A subchronic toxicity study of elemental Nano-Se in Sprague-Dawley rats.

    PubMed

    Jia, X; Li, N; Chen, J

    2005-03-11

    The subchronic toxicity of Nano-Se was compared with selenite and high-selenium protein in rats. Groups of Sprague-Dawley rats (12 males and 12 females per group) were fed diets containing Nano-Se, selenite and high-selenium protein at concentrations of 0, 2, 3, 4 and 5 ppm Se, respectively, for 13 weeks. Clinical observations were made and body weight and food consumption were recorded weekly. At the end of the study, the rats were subjected to a full necropsy, blood samples were collected for hematology and clinical chemistry determination. Histopathological examination was performed on selected tissues. At the two higher doses (4 and 5 ppm Se), significant abnormal changes were found in body weight, hematology, clinical chemistry, relative organ weights and histopathology parameters. However, the toxicity was more pronounced in the selenite and high-selenium protein groups than the Nano-Se group. At the dose of 3 ppm Se, significant growth inhibition and degeneration of liver cells were found in the selenite and high-selenium protein groups. No changes attributable to administration of Nano-Se at the dose of 3 ppm Se were found. Taken together, the no-observed-adverse-effect level (NOAEL) of Nano-Se in male and female rats was considered to be 3 ppm Se, equivalent to 0.22 mg/kg bw/day for males and 0.33 mg/kg bw/day for females. On the other hand, the NOAELs of selenite and high-selenium protein in males and females were considered to be 2 ppm Se, equivalent to 0.14 mg/kg bw/day for males and 0.20 mg/kg bw/day for females. In addition, studies have shown that Nano-Se has a similar bioavailability in rat, and much less acute toxicity in mice compared with selenite. In conclusion, Nano-Se is less toxic than selenite and high-selenium protein in the 13-week rat study.

  15. Grain Refinement and Mechanical Properties of Cu–Cr–Zr Alloys with Different Nano-Sized TiCp Addition

    PubMed Central

    Zhang, Dongdong; Bai, Fang; Wang, Yong; Wang, Jinguo; Wang, Wenquan

    2017-01-01

    The TiCp/Cu master alloy was prepared via thermal explosion reaction. Afterwards, the nano-sized TiCp/Cu master alloy was dispersed by electromagnetic stirring casting into the melting Cu–Cr–Zr alloys to fabricate the nano-sized TiCp-reinforced Cu–Cr–Zr composites. Results show that nano-sized TiCp can effectively refine the grain size of Cu–Cr–Zr alloys. The morphologies of grain in Cu–Cr–Zr composites changed from dendritic grain to equiaxed crystal because of the addition and dispersion of nano-sized TiCp. The grain size decreased from 82 to 28 μm with the nano-sized TiCp content. Compared with Cu–Cr–Zr alloys, the ultimate compressive strength (σUCS) and yield strength (σ0.2) of 4 wt% TiCp-reinforced Cu–Cr–Zr composites increased by 6.7% and 9.4%, respectively. The wear resistance of the nano-sized TiCp-reinforced Cu–Cr–Zr composites increased with the increasing nano-sized TiCp content. The wear loss of the nano-sized TiCp-reinforced Cu–Cr–Zr composites decreased with the increasing TiCp content under abrasive particles. The eletrical conductivity of Cu–Cr–Zr alloys, 2% and 4% nano-sized TiCp-reinforced Cu–Cr–Zr composites are 64.71% IACS, 56.77% IACS and 52.93% IACS, respectively. PMID:28786937

  16. [Comparative study of nanosized and microsized silicon dioxide on spermatogenesis function of male rats].

    PubMed

    Fan, Yi-Ou; Zhang, Ying-Hua; Zhang, Xiao-Peng; Liu, Bing; Ma, Yi-xin; Jin, Yi-he

    2006-09-01

    To compare the effects of nanosized and microsized silicon dioxide on spermatogenesis function of male rats exposed by inhalation. 45 male rats were randomly divided into control group and four experimental groups which were exposed by 100 mg/m3 or 300 mg/m3 nanosized and microsized silicon dioxide in inhalation chambers 2 hours every other day. Age-matched rats were exposed to room air with the same condition and served as controls. 65 days later, the testicular and epididymal viscera coefficients, the quantity and quality of sperm were examined and the histopathological assessment was done. The changes in biochemical parameters in serum and testes were also measured. Nanosized silicon dioxide could induce histopathological changes of testes in rats, and the effect was higher than that of microsized particles at the same concentration. Nanosized silicon dioxide could reduce the sperm counts of rats and the testicular LDH-C4 activities, increase MDA levels in the testes and the effect was higher than that of microsized particles at the same concentration. Nanosized silicon dioxide could lead to the reduction of sperm motility, testicular LDH-C4 activities and 8-hydroxydeoxyguanosine (8-OHdG) concentration in serum elevation in particles-exposed rats compared with the control animals, but there are no significant difference compared with that of microsized particles at the same concentration. The present findings suggest a different effect of impairment of sperm production and maturation induced by inhalation of nanosized and microsized silicon dioxide, and nanosized silicon dioxide exerted more severe reaction.

  17. Grain Refinement and Mechanical Properties of Cu-Cr-Zr Alloys with Different Nano-Sized TiCp Addition.

    PubMed

    Zhang, Dongdong; Bai, Fang; Wang, Yong; Wang, Jinguo; Wang, Wenquan

    2017-08-08

    The TiC p /Cu master alloy was prepared via thermal explosion reaction. Afterwards, the nano-sized TiC p /Cu master alloy was dispersed by electromagnetic stirring casting into the melting Cu-Cr-Zr alloys to fabricate the nano-sized TiC p -reinforced Cu-Cr-Zr composites. Results show that nano-sized TiC p can effectively refine the grain size of Cu-Cr-Zr alloys. The morphologies of grain in Cu-Cr-Zr composites changed from dendritic grain to equiaxed crystal because of the addition and dispersion of nano-sized TiC p . The grain size decreased from 82 to 28 μm with the nano-sized TiC p content. Compared with Cu-Cr-Zr alloys, the ultimate compressive strength (σ UCS ) and yield strength (σ 0.2 ) of 4 wt% TiC p -reinforced Cu-Cr-Zr composites increased by 6.7% and 9.4%, respectively. The wear resistance of the nano-sized TiCp-reinforced Cu-Cr-Zr composites increased with the increasing nano-sized TiCp content. The wear loss of the nano-sized TiC p -reinforced Cu-Cr-Zr composites decreased with the increasing TiC p content under abrasive particles. The eletrical conductivity of Cu-Cr-Zr alloys, 2% and 4% nano-sized TiCp-reinforced Cu-Cr-Zr composites are 64.71% IACS, 56.77% IACS and 52.93% IACS, respectively.

  18. Creation of deep blue light emitting nitrogen-vacancy center in nanosized diamond

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Himics, L., E-mail: himics.laszlo@wigner.mta.hu; Tóth, S.; Veres, M.

    2014-03-03

    This paper reports on the formation of complex defect centers related to the N3 center in nanosized diamond by employing plasma immersion and focused ion beam implantation methods. He{sup +} ion implantation into nanosized diamond “layer” was performed with the aim of creating carbon atom vacancies in the diamond structure, followed by the introduction of molecular N{sub 2}{sup +} ion and heat treatment in vacuum at 750 °C to initiate vacancy diffusion. To decrease the sp{sup 2} carbon content of nanosized diamond formed during the implantation processes, a further heat treatment at 450 °C in flowing air atmosphere was used. The modificationmore » of the bonding properties after each step of defect creation was monitored by Raman scattering measurements. The fluorescence measurements of implanted and annealed nanosized diamond showed the appearance of an intensive and narrow emission band with fine structures at 2.98 eV, 2.83 eV, and 2.71 eV photon energies.« less

  19. Nano-sized ZnO powders prepared by co-precipitation method with various pH

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Purwaningsih, S. Y., E-mail: sriyanisaputri@gmail.com; Pratapa, S.; Triwikantoro,

    2016-04-19

    In this work, nano-sized ZnO powders have been synthesized by the co-precipitation method with Zn(CH3COOH)2.2H2O, HCl, and NH3.H2O as raw materials in various pH ranging from 8 to 10. The purity, microstructure, chemical group analysis, morphology of the prepared ZnO powders were studied by X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), energy dispersive X-ray spectrometry (EDX), and scanning electron microscope (SEM), respectively. Rietveld refinement of XRD data showed that ZnO crystallizes in the wurtzite structure with high purity. The obtained powders were nano-sized particles with the average crystallite size about 17.9 ± 2.1 nm synthesized with pH of 9.5, atmore » 85°C, and stirring time of 6 h. The SEM results have visualied the morphology of ZnO nanoparticles with spherical-like shape. The effect of processing conditions on morphology of ZnO was also discussed.« less

  20. Influence of acetazolamide loading on the (in vitro) performances of non-phospholipid-based cationic nanosized emulsion in comparison with phospholipid-based anionic and neutral-charged nanosized emulsions.

    PubMed

    Tamilvanan, Shunmugaperumal; Kumar, Balakrishnan Ajith

    2011-09-01

    Acetazolamide (ACZM)-loaded anionic, cationic, and neutral-charged oil-in-water nanosized emulsions were prepared and compared with their mean droplet diameter, surface charge, entrapment efficiency, freeze-thaw cycling stability, in vitro drug release, and transcorneal permeation. The present study aims to determine the influence of ACZM loading on the performances of non-phospholipid-based cationic nanosized emulsion in comparison with phospholipid-based anionic and neutral-charged nanosized emulsions. Regardless of charges, all of these emulsions exhibited a nanometer range mean particle diameter (240-443 nm) following autoclave sterilization. While the anionic and cationic emulsions did show high negative (-36.9 mV) and positive zeta potential (+41.4 mV) values, the neutral-charged emulsion did not. Presence of cryoprotectants (5% w/w sucrose + 5% w/w sorbitol) improved the stability of cationic emulsion to droplet aggregation during freeze-thaw cycling. The in vitro release kinetic behavior of drug exchange with physiological anions present in the simulated tear solution appears to be complex and difficult to characterize using mathematical fitting model equations. Augmentation in drug permeation through goat cornea, in vitro, was noticed for cationic emulsion. ACZM-loaded cationic nanosized emulsion could be suitable for topical application into eye to elicit better therapeutic effect in comparison with its anionic and neutral-charged emulsions.

  1. Reversible Li storage for nanosize cation/anion-disordered rocksalt-type oxyfluorides: LiMoO2 - x LiF (0 ≤ x ≤ 2) binary system

    NASA Astrophysics Data System (ADS)

    Takeda, Nanami; Hoshino, Satoshi; Xie, Lixin; Chen, Shuo; Ikeuchi, Issei; Natsui, Ryuichi; Nakura, Kensuke; Yabuuchi, Naoaki

    2017-11-01

    A binary system of LiMoO2 - x LiF (0 ≤ x ≤ 2), Li1+xMoO2Fx, is systematically studied as potential positive electrode materials for rechargeable Li batteries. Single phase and nanosized samples on this binary system are successfully prepared by using a mechanical milling route. Crystal structures and Li storage properties on the binary system are also examined. Li2MoO2F (x = 1), which is classified as a cation-/anion-disordered rocksalt-type structure and is a thermodynamically metastable phase, delivers a large reversible capacity of over 300 mAh g-1 in Li cells with good reversibility. Highly reversible Li storage is realized for Li2MoO2F consisting of nanosized particles based on Mo3+/Mo5+ two-electron redox as evidenced by ex-situ X-ray absorption spectroscopy coupled with ex-situ X-ray diffractometry. Moreover, the presence of the most electronegative element in the framework structure effectively increases the electrode potential of Mo redox through an inductive effect. From these results, potential of nanosized lithium molybdenum oxyfluorides for high-capacity positive electrode materials of rechargeable Li batteries are discussed.

  2. Structure of Nano-sized CeO 2 Materials: Combined Scattering and Spectroscopic Investigations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Marchbank, Huw R.; Clark, Adam H.; Hyde, Timothy I.

    Here, the nature of nano-sized ceria, CeO 2, systems were investigated using neutron and X-ray diffraction and X-ray absorption spectroscopy. Whilst both diffraction andtotal pair distribution functions (PDFs) revealed that in all the samples the occupancy of both Ce 4+ and O 2- are very close to the ideal stoichiometry, the analysis using reverse Monte Carlo technique revealedsignificant disorder around oxygen atoms in the nano sized ceria samples in comparison to the highly crystalline NIST standard.In addition, the analysis reveal that the main differences observed in the pair correlations from various X-ray and neutron diffraction techniques were attributed to themore » particle size of the CeO 2 prepared by the reported three methods. Furthermore, detailed analysis of the Ce L 3– and K-edge EXAFS data support this finding; in particular the decrease in higher shell coordination numbers with respect to the NIST standard, are attributed to differences in particle size.« less

  3. Structure of Nano-sized CeO 2 Materials: Combined Scattering and Spectroscopic Investigations

    DOE PAGES

    Marchbank, Huw R.; Clark, Adam H.; Hyde, Timothy I.; ...

    2016-08-29

    Here, the nature of nano-sized ceria, CeO 2, systems were investigated using neutron and X-ray diffraction and X-ray absorption spectroscopy. Whilst both diffraction andtotal pair distribution functions (PDFs) revealed that in all the samples the occupancy of both Ce 4+ and O 2- are very close to the ideal stoichiometry, the analysis using reverse Monte Carlo technique revealedsignificant disorder around oxygen atoms in the nano sized ceria samples in comparison to the highly crystalline NIST standard.In addition, the analysis reveal that the main differences observed in the pair correlations from various X-ray and neutron diffraction techniques were attributed to themore » particle size of the CeO 2 prepared by the reported three methods. Furthermore, detailed analysis of the Ce L 3– and K-edge EXAFS data support this finding; in particular the decrease in higher shell coordination numbers with respect to the NIST standard, are attributed to differences in particle size.« less

  4. Vapor-phase photo-oxidation of methanol over nanosize titanium dioxide clusters dispersed in MCM-41 host material part 1: synthesis and characterization.

    PubMed

    Bhattacharya, K; Tripathi, A K; Dey, G K; Gupta, N M

    2005-05-01

    Nanosize clusters of titania were dispersed in mesoporous MCM-41 silica matrix with the help of the incipient wet-impregnation route, using an isopropanol solution of titanium isopropoxide as precursor. The clusters thus formed were of pure anatase phase and their size depended upon the titania loading. In the case of low (< 15 wt %) loadings, the TiO2 particles were X-ray and laser-Raman amorphous, confirming very high dispersion. These particles were mostly of < or = 2 nm size. On the other hand, larger size clusters (2-15 nm) were present in a sample with a higher loading of approximately 21 wt %. These particles of titania, irrespective of their size, exhibited an absorbance behavior similar to that of bulk TiO2. Powder X-ray diffraction, N2-adsorption and transmission electron microscopy results showed that while smaller size particles were confined mostly inside the pore system, the larger size particles occupied the external surface of the host matrix. At the same time, the structural integrity of the host was maintained even though some deformation in the pore system was noticed in the case of the sample having highest loading. The core level X-ray photoelectron spectroscopy results revealed a + 4 valence state of Ti in all the samples. A positive binding energy shift and the increase of the width of Ti 2p peaks were observed, however, with the decrease in the particle size of supported titania crystallites, indicative of a microenvironment for surface sites that is different from that of the bulk.

  5. In Situ Synthesis of Vertical Standing Nanosized NiO Encapsulated in Graphene as Electrodes for High-Performance Supercapacitors.

    PubMed

    Lin, Jinghuang; Jia, Henan; Liang, Haoyan; Chen, Shulin; Cai, Yifei; Qi, Junlei; Qu, Chaoqun; Cao, Jian; Fei, Weidong; Feng, Jicai

    2018-03-01

    NiO is a promising electrode material for supercapacitors. Herein, the novel vertically standing nanosized NiO encapsulated in graphene layers (G@NiO) are rationally designed and synthesized as nanosheet arrays. This unique vertical standing structure of G@NiO nanosheet arrays can enlarge the accessible surface area with electrolytes, and has the benefits of short ion diffusion path and good charge transport. Further, an interconnected graphene conductive network acts as binder to encapsulate the nanosized NiO particles as core-shell structure, which can promote the charge transport and maintain the structural stability. Consequently, the optimized G@NiO hybrid electrodes exhibit a remarkably enhanced specific capacity up to 1073 C g -1 and excellent cycling stability. This study provides a facial strategy to design and construct high-performance metal oxides for energy storage.

  6. Coordination polymer-derived nano-sized zinc ferrite with excellent performance in nitro-explosive detection.

    PubMed

    Singha, Debal Kanti; Mahata, Partha

    2017-08-29

    Herein, a mixed metal coordination polymer, {(H 2 pip)[Zn 1/3 Fe 2/3 (pydc-2,5) 2 (H 2 O)]·2H 2 O} 1 {where H 2 pip = piperazinediium and pydc-2,5 = pyridine-2,5-dicarboxylate}, was successfully synthesized using a hydrothermal technique. To confirm the structure and phase purity of 1, single crystals of an isomorphous pure Fe compound, {(H 2 pip)[Fe(pydc-2,5) 2 (H 2 O)]·2H 2 O} 1a, were synthesized based on similar synthetic conditions. Single crystal X-ray data of 1a confirmed the one-dimensional anionic metal-organic coordination polymer hydrogen bonded with protonated piprazine (piperazinediium) and lattice water molecules. The phase purity of 1 and 1a were confirmed via powder X-ray diffraction. Compound 1 was systematically characterized using IR, TGA, SEM, and EDX elemental mapping analysis. Compound 1 was used as a single source precursor for the preparation of nano-sized ZnFe 2 O 4 via thermal decomposition. The as-obtained ZnFe 2 O 4 was fully characterized using PXRD, SEM, TEM, and EDX elemental mapping analysis. It was found that ZnFe 2 O 4 was formed in its pure form with particle size in the nano-dimension. The aqueous dispersion of nano-sized ZnFe 2 O 4 exhibits a strong emission at 402 nm upon excitation at 310 nm. This emissive property was employed for luminescence-based detection of nitroaromatic explosives in an aqueous medium through luminescence quenching for the first time. Importantly, selective detections have been observed for phenolic nitroaromatics based on differential luminescence quenching behaviour along with a detection limit of 57 ppb for 2,4,6-trinitrophenol (TNP) in water.

  7. Nano-sized Adsorbate Structure Formation in Anisotropic Multilayer System

    NASA Astrophysics Data System (ADS)

    Kharchenko, Vasyl O.; Kharchenko, Dmitrii O.; Yanovsky, Vladimir V.

    2017-05-01

    In this article, we study dynamics of adsorbate island formation in a model plasma-condensate system numerically. We derive the generalized reaction-diffusion model for adsorptive multilayer system by taking into account anisotropy in transfer of adatoms between neighbor layers induced by electric field. It will be found that with an increase in the electric field strength, a structural transformation from nano-holes inside adsorbate matrix toward separated nano-sized adsorbate islands on a substrate is realized. Dynamics of adsorbate island sizes and corresponding distributions are analyzed in detail. This study provides an insight into details of self-organization of adatoms into nano-sized adsorbate islands in anisotropic multilayer plasma-condensate systems.

  8. An electrochemical sensor based on nitrogen doped carbon material prepared from nitrogen-containing precursors

    NASA Astrophysics Data System (ADS)

    Cui, G. Y.; Wang, C. Y.; Xiang, G. Q.; Zhou, B.

    2018-01-01

    In this work, a nitrogen doped carbon material (NDC) was prepared by using a copper adenine complex as precursor and applied to electrochemical sensing of Vitamin B2 (VB2). The experimental results show that the nitrogen doped carbon material is obtained after calcination at 650 °C under argon atmosphere, afterwards, which were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), fourier transform infrared (FT-IR), and electrochemical method. According to the XRD data, the product was a carbon material, and infrared data demonstrates that there are two kinds of carbonyl nitrogen combination, respectively, C-N and C = N combination of ways. Importantly, we used NDC to construct electrochemical biosensor to detect VB2 by differential pulse voltammetry (DPV). The linear range was 6 × 10-6 - 3.5 × 10-4 M (R=0.9962), the minimum detection limit was 5.4 × 10-6 M, and the sensitivity is better. Consequently, it has better sensing performance.

  9. Role of bulk and Nanosized SiO2 to overcome salt stress during Fenugreek germination (Trigonella foenum- graceum L.).

    PubMed

    Ivani, Reihane; Sanaei Nejad, Seyed Hossein; Ghahraman, Bijan; Astaraei, Ali Reza; Feizi, Hassan

    2018-04-05

    The effects of bulk and Nanosized SiO 2 on seed germination and seedling growth indices of fenugreek under salinity stress were studied in the College of Agriculture, Ferdowsi University of Mashhad, Iran, in 2013. The experimental treatments included 4 levels of salinity stress (0, 50, 100 and 150 mM), 2 concentrations of bulk (50 and 100 ppm), 2 concentrations of nanosized SiO 2 (50 and 100 ppm), and control (without any SiO 2 types). Seedling growth attributes significantly improved when bulk and nanosized SiO 2 concentrations applied singly or with different levels of salt stress. However, they significantly declined with salt application. The adverse effects of salt on shoot, root and seedling lengths were alleviated by application of 50 ppm nanosized SiO 2 treatment. Under salt stress condition, addition of 50 and 100 ppm nanosized SiO 2 to fenugreek seeds increased shoot, root and seedling dry weights as compared to bulk SiO 2 concentrations and control treatments, though 50 ppm nanosized SiO 2 was more effective than 100 ppm nanosized SiO 2 application. It was concluded that nanosized SiO 2 improves growth attributes of fenugreek and mitigate adverse effects of salt stress.

  10. EASY SYNTHESIS OF Li4Ti5O12/C MICROSPHERES CONTAINING NANOPARTICLES AS ANODE MATERIAL FOR HIGH-RATE Li-ION BATTERIES

    NASA Astrophysics Data System (ADS)

    Zheng, Xiaodong; Dong, Lina; Dong, Chenchu

    2014-01-01

    A microspherical Li4Ti5O12/C composite composed of interconnected nanoparticles with BP-2000 carbon black as carbon source is synthesized for use as an anode material in high-power lithium-ion batteries. The composite is prepared through precursor pretreatment including pre-sintering, ball-milling, and spray-drying. The structure, size and surface morphology of the as-prepared particles are investigated by X-ray diffraction and scanning electron microscopy. Results show that the obtained material has a microspherical morphology consisting of nanosized prime particles with compact structure. The precursor pretreatment effectively reduced the agglomeration of the prime particles caused by high temperature sintering and led to a more uniform distribution of BP-2000 on the surface of prime particles generating highly efficient conductive network. The specific capacity of the electrode at 20 C rate is 131 mAh g-1 and the loss of capacity is less than 2% after the 60 variation cycles (from 1 C to 20 C and back to 1 C). This excellent performance is attributed to the effective conductive network between the prime particles and the reduction of the lithium-ion diffusion pathway.

  11. Exceptional capability of nanosized CeO(2) materials to "dissolve" lanthanide oxides established by time-gated excitation and emission spectroscopy.

    PubMed

    Tiseanu, Carmen; Parvulescu, Vasile; Avram, Daniel; Cojocaru, Bogdan; Sanchez-Dominguez, Margarita

    2014-05-28

    The atomic scale homogeneity of Ce and Zr oxygen bonds represents the main reason for enhanced total oxygen storage capability of CeO2-ZrO2 (Ce/Zr = 1) as compared to that of CeO2. Here, we demonstrate that the addition of 10% Eu(3+) by wet impregnation on preformed nanosized CeO2-ZrO2 (Ce/Zr = 1) followed by calcination induces a remarkable homogeneity of 10% Eu(3+)-CeO2-ZrO2 solid solution. By use of time-resolved emission and excitation spectroscopies, the improvement of the nanoscale chemical and structural homogeneity of 10% Eu(3+)-CeO2-ZrO2 calcined at 1000 as compared to sample calcined at 750 °C is demonstrated. Based on the comparison of luminescence properties of 10% Eu(3+) impregnated on preformed nanosized CeO2-ZrO2 and CeO2, we also show that the presence of zirconium does not only preserve the ability of cerium oxide to "dissolve" lanthanide oxide, but also determines an important stabilization of defects (oxygen vacancies) generated upon Eu(3+) doping.

  12. Nanosized Building Blocks for Customizing Novel Antibiofilm Approaches

    PubMed Central

    Paula, A.J.; Koo, H.

    2016-01-01

    Recent advances in nanotechnology provide unparalleled flexibility to control the composition, size, shape, surface chemistry, and functionality of materials. Currently available engineering approaches allow precise synthesis of nanocompounds (e.g., nanoparticles, nanostructures, nanocrystals) with both top-down and bottom-up design principles at the submicron level. In this context, these “nanoelements” (NEs) or “nanosized building blocks” can 1) generate new nanocomposites with antibiofilm properties or 2) be used to coat existing surfaces (e.g., teeth) and exogenously introduced surfaces (e.g., restorative or implant materials) for prevention of bacterial adhesion and biofilm formation. Furthermore, functionalized NEs 3) can be conceived as nanoparticles to carry and selectively release antimicrobial agents after attachment or within oral biofilms, resulting in their disruption. The latter mechanism includes “smart release” of agents when triggered by pathogenic microenvironments (e.g., acidic pH or low oxygen levels) for localized and controlled drug delivery to simultaneously kill bacteria and dismantle the biofilm matrix. Here we discuss inorganic, metallic, polymeric, and carbon-based NEs for their outstanding chemical flexibility, stability, and antibiofilm properties manifested when converted into bioactive materials, assembled on-site or delivered at biofilm-surface interfaces. Details are provided on the emerging concept of the rational design of NEs and recent technological breakthroughs for the development of a new generation of nanocoatings or functional nanoparticles for biofilm control in the oral cavity. PMID:27856967

  13. Nanosized Building Blocks for Customizing Novel Antibiofilm Approaches.

    PubMed

    Paula, A J; Koo, H

    2017-02-01

    Recent advances in nanotechnology provide unparalleled flexibility to control the composition, size, shape, surface chemistry, and functionality of materials. Currently available engineering approaches allow precise synthesis of nanocompounds (e.g., nanoparticles, nanostructures, nanocrystals) with both top-down and bottom-up design principles at the submicron level. In this context, these "nanoelements" (NEs) or "nanosized building blocks" can 1) generate new nanocomposites with antibiofilm properties or 2) be used to coat existing surfaces (e.g., teeth) and exogenously introduced surfaces (e.g., restorative or implant materials) for prevention of bacterial adhesion and biofilm formation. Furthermore, functionalized NEs 3) can be conceived as nanoparticles to carry and selectively release antimicrobial agents after attachment or within oral biofilms, resulting in their disruption. The latter mechanism includes "smart release" of agents when triggered by pathogenic microenvironments (e.g., acidic pH or low oxygen levels) for localized and controlled drug delivery to simultaneously kill bacteria and dismantle the biofilm matrix. Here we discuss inorganic, metallic, polymeric, and carbon-based NEs for their outstanding chemical flexibility, stability, and antibiofilm properties manifested when converted into bioactive materials, assembled on-site or delivered at biofilm-surface interfaces. Details are provided on the emerging concept of the rational design of NEs and recent technological breakthroughs for the development of a new generation of nanocoatings or functional nanoparticles for biofilm control in the oral cavity.

  14. New polymeric precursors to SiNCB, BN, and La(3)Ni(2)B(2)N(3) materials

    NASA Astrophysics Data System (ADS)

    Wideman, Thomas W.

    Boron-containing non-oxide ceramics demonstrate a number of important structural, electronic and physical properties. However, the lack of general synthetic routes to generate these materials with controlled composition, under moderate conditions, and in processed forms, has hampered both scientific studies and practical applications. The goal of the work described in this dissertation was to develop efficient new polymeric precursor routes to boron-containing materials including SiNCB ceramics composites, boron nitride fibers, and quaternary metal boro-nitride superconductors. Two types of polyborosilazane precursors to SiNCB ceramics were developed. Borazine-co-silazane copolymers were prepared through the thermal copolymerization of borazine with two silazanes, tris(trimethylsilylamino)silane, and 1,1,3,3,5,5 -hexamethylcyclotrisilazane. Polyborosilazanes with pendent boron-containing species were obtained by the modification of preformed hydridopolysilazane polymers with three monofunctional boranes: pinacolborane, 2,4-diethylborazine and 1,3-dimethyl-1,3-diaza-2-boracyclopentane. Pyrolyses of both types of polyborosilazanes produced SiNCB ceramics with controllable boron contents, enhanced thermal stabilities, and reduced crystallinity. Processible polymeric precursors to BN were also achieved by the chemical modification of polyborazylene, (Bsb3Nsb3Hsb{˜ 4}rbrack sb{x}, with diethylamine, dipentylamine, and hexamethyldisilazane. The modified polymers, unlike the parent polyborazylene, do not crosslink at low temperatures, and therefore proved to be ideal melt-spinnable precursors to BN ceramic fibers. A new polymeric precursor route to the recently discovered Lasb3Nisb2Bsb2Nsb3 superconductor (Tc = 12K) was developed by reacting lanthanum and nickel powders dispersed in the polyborazylene, to produce the intermetallic in excellent yields. The use of the polymer as a "reagent" provided a controllable, solid state source of nitrogen, and allows for the large

  15. Thermal Studies of New Precursors to Indium-tin Oxides for Use as Sensor Materials in the Detection of NO(x)

    NASA Technical Reports Server (NTRS)

    Goldsby, J. C.; Kacik, T.; Hockensmith, C. M.

    1999-01-01

    Control of combustion product emissions in both sub and super-sonic jet engines can be facilitated by measurement of NO(x) levels with metal oxide sensors, In2O3, metal-doped SnO2, and SnO, (as well as other materials) show resistivity changes in the presence of NO(x), but often their sensitivity, stability, and selectivity are low. This study was designed to develop new synthetic pathways to precursors that produce high purity, two phase In2O3-SnO2. The precursors were formed by complexation of tin with any oxide ligands to give the ammonium salt (NH4). Thermal studies of these precursors were carried out by thermal gravimetry (TG) and differential scanning calorimetry (DSC). Further studies by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR) were also conducted.

  16. One-pot synthesis of carbon-coated nanosized LiTi2(PO4)3 as anode materials for aqueous lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Liu, Zhantao; Qin, Xusong; Xu, Hui; Chen, Guohua

    2015-10-01

    In this study, a one-pot sintering process incorporating sol-gel preparation route and in-situ carbon coating was proposed for the synthesis of carbon-coated nanosized LiTi2(PO4)3. Experimental results show that the prepared LiTi2(PO4)3 particles are of high crystallinity and well-coated by turbostratic carbon. Attributed to nanosized particles and enhanced conductivity provided by turbostratic carbon coating, the carbon-coated LiTi2(PO4)3 showed high rate performance and good cycling life in aqueous electrolyte. Particularly, the carbon-coated LiTi2(PO4)3 exhibited initial specific capacities of 103 and 89 mAh g-1, and retained 80.6% and 97% of the initial capacities after 120 cycles at 1C and 10C in aqueous electrolyte, respectively. The high rate performance and good cycling life of carbon-coated LiTi2(PO4)3 in aqueous electrolyte reveal its potential as negative electrode in aqueous lithium-ion batteries for electric vehicles and industrial-scale energy storage systems.

  17. Evaluation of nanoselenium (Nano-Se) effect on hematological and serum biochemical parameters of rat in experimentally lead poisoning.

    PubMed

    Dehkordi, A Jafari; Mohebbi, A N; Aslani, M R; Ghoreyshi, S M

    2017-04-01

    The present study was designed to evaluate the effect of nanoselenium (Nano-Se) on hematological and biochemical parameters of rats experimentally intoxicated with lead (Pb). Thirty male rats were randomly divided into six groups as follows: the control, selenite, Nano-Se, Pb group, Pb + selenite, and Pb + Nano-Se groups. After 35 days, blood was collected from rats and hematology and serum biochemical parameters of oxidative stress were measured. The thiobarbituric acid reactive substances (TBARS) level of Pb group was significantly higher than other groups. Also, TBARS level was significantly lower in the Pb + Nano-Se group than Pb + selenite group. The serum superoxide dismutase activities were significantly lower in Pb group than the control, Pb + selenite, and Pb + Nano-Se groups. The catalase activities in the Pb group showed no significant change when compared to other groups. In the Pb group, packed cell volume was lower than the control group. A significant difference was observed between the control group and the Pb, Pb + selenite, and Pb + Nano-Se groups. In the Pb group, the numbers of white blood cell (WBC) decreased in comparison with the control group. Also, there was significant increase in WBC counts in the Pb + Nano-Se and Pb + selenite groups in comparison with Pb group. The number of lymphocytes in the Pb group decreased in comparison with the control group. By comparing the means of the Pb + Nano-Se and Pb + selenite groups together, it was determined that there were significant differences in the lymphocytes and neutrophil counts. In conclusion, usage of selenium compounds particularly Nano-Se particles inhibits the adverse effects of Pb on antioxidant activity and immune system function in the Pb poisoning.

  18. Snow-borne nanosized particles: Abundance, distribution, composition, and significance in ice nucleation processes

    NASA Astrophysics Data System (ADS)

    Rangel-Alvarado, Rodrigo Benjamin; Nazarenko, Yevgen; Ariya, Parisa A.

    2015-11-01

    Physicochemical processes of nucleation constitute a major uncertainty in understanding aerosol-cloud interactions. To improve the knowledge of the ice nucleation process, we characterized physical, chemical, and biological properties of fresh snow using a suite of state-of-the-art techniques based on mass spectrometry, electron microscopy, chromatography, and optical particle sizing. Samples were collected at two North American Arctic sites, as part of international campaigns (2006 and 2009), and in the city of Montreal, Canada, over the last decade. Particle size distribution analyses, in the range of 3 nm to 10 µm, showed that nanosized particles are the most numerous (38-71%) in fresh snow, with a significant portion (11 to 19%) less than 100 nm in size. Particles with diameters less than 200 nm consistently exhibited relatively high ice-nucleating properties (on average ranged from -19.6 ± 2.4 to -8.1 ± 2.6°C). Chemical analysis of the nanosized fraction suggests that they contain bioorganic materials, such as amino acids, as well as inorganic compounds with similar characteristics to mineral dust. The implication of nanoparticle ubiquity and abundance in diverse snow ecosystems are discussed in the context of their importance in understanding atmospheric nucleation processes.

  19. Growth of vertically aligned carbon nanotubes on silicon and quartz substrate by spray pyrolysis of a natural precursor: Turpentine oil

    NASA Astrophysics Data System (ADS)

    Afre, Rakesh A.; Soga, T.; Jimbo, T.; Kumar, Mukul; Ando, Y.; Sharon, M.

    2005-10-01

    Vertically aligned carbon nanotubes (VACNTs) were grown by spray pyrolysis of turpentine oil and ferrocene mixture at 700 °C. Using this simple method, we report the successful growth of vertically aligned nanotubes of 300 μm length and diameter in the range of 50-100 nm on Si(1 0 0) substrate. The ferrocene act as an in situ Fe catalyst precursor and forming the nanosize iron particles for formation of VACNTs on Si and quartz substrates. Morphological differences between aligned carbon nanotubes grown on different substrates are studied and discussed by SEM, TEM and Raman spectroscopy characterizations.

  20. A submerged ceramic membrane reactor for the p-nitrophenol hydrogenation over nano-sized nickel catalysts.

    PubMed

    Chen, R Z; Sun, H L; Xing, W H; Jin, W Q; Xu, N P

    2009-02-01

    The catalytic hydrogenation of p-nitrophenol to p-aminophenol over nano-sized nickel catalysts was carried out in a submerged ceramic membrane reactor. It has been demonstrated that the submerged ceramic membrane reactor is more suitable for the p-nitrophenol hydrogenation over nano-sized nickel catalysts compared with the side-stream ceramic membrane reactor, and the membrane module configuration has a great influence on the reaction rate of p-nitrophenol hydrogenation and the membrane treating capacity. The deactivation of nano-sized nickel is mainly caused by the adsorption of impurity on the surface of nickel and the increase of oxidation degree of nickel.

  1. Photo-triggered release in polyamide nanosized capsules

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Marturano, V.; Ambrogi, V.; Cerruti, P.

    2014-05-15

    In this work, nanosized capsules based on a lightly cross-linked polyamide containing azobenzene moieties in the main chain were synthesized by miniemulsion interfacial polymerization. The obtained nanocapsules were loaded either with toluene or with the fluorescent probe coumarin-6 as a core. Diameters of the nanocapsules were in the 100-900 nm range, depending on the selected emulsion conditions. The morphology and shape of the samples were observed by TEM and SEM while the emulsion droplets and nanocapsules size was measured by DLS. Under continuous UV irradiation the polymer underwent E-Z photoisomerization allowing the release of the encapsulated material. Variation in diametermore » of the nanocapsules with the time of UV irradiation was detected through DLS analysis. 10-30% growth was observed, depending on the sample. The kinetics of release of coumarin-6 was followed by spectrofluorimetry in ethanol. In absence of irradiation, the fluorescence intensity appeared to be constant over time, while it increased when the sample was irradiated with 360 nm UV light.« less

  2. Synthesis and characterization of nano-sized CaCO3 in purified diet

    NASA Astrophysics Data System (ADS)

    Mulyaningsih, N. N.; Tresnasari, D. R.; Ramahwati, M. R.; Juwono, A. L.; Soejoko, D. S.; Astuti, D. A.

    2017-07-01

    The growth and development of animals depend strongly on the balanced nutrition in the diet. This research aims is to characterize the weight variations of nano-sized calcium carbonate (CaCO3) in purified diet that to be fed to animal model of rat. The nano-sized CaCO3 was prepared by milling the calcium carbonate particles for 20 hours at a rotation speed of 1000 rpm and resulting particle size in a range of 2-50 nm. Nano-sized CaCO3 added to purified diet to the four formulas that were identified as normal diet (N), deficiency calcium (DC), rich in calcium (RC), and poor calcium (PC) with containing in nano-sized CaCO3 much as 0.50 %, 0.00 %, 0.75 % and 0.25 % respectively. The nutritional content of the purified diet was proximate analyzed, it resulted as followed moisture, ash, fat, protein, crude fiber. The quantities of chemical element were analyzed by atomic absorption spectrometry (AAS), it resulted iron, magnesium, potassium and calcium. The results showed that N diet (Ca: 16,914.29 ppm) were suggested for healthy rats and RC diet (Ca: 33,696.13 ppm) for conditioned osteoporosis rats. The crystalline phases of the samples that were examined by X-ray diffraction showed that crystalline phase increased with the increasing concentration of CaCO3.

  3. Pilot scale application of nanosized iron oxides as electron acceptors for bioremediation

    NASA Astrophysics Data System (ADS)

    Bosch, Julian; Fritzsche, Andreas; Frank-Fahle, Beatrice; Lüders, Tilmann; Höss, Sebastian; Eisenmann, Heinrich; Held, Thomas; Totsche, Kai U.; Meckenstock, Rainer U.

    2014-05-01

    Microbial reduction of ferric iron is a major biogeochemical process in groundwater aquifer ecosystems and often associated with the degradation of organic contaminants, as bacteria couple iron reduction to the oxidation reduced carbon like e.g. BTEX. Yet in general the low bioavailability of natural iron oxides limits microbial reduction rates. However, nanosized iron oxides have an unequally enhanced bioavailability and reactivity compared to their respective bulk, macro-sized, and more crystalline materials. At the same time, nanosized iron oxides can be produced in stable colloidal suspensions, permitting efficient injections into contaminated aquifers. We examined the reactivity of nanosized synthetic colloidal iron oxides in microbial iron reduction. Application of colloidal nanoparticles led to a strong and sustainable enhancement of microbial reaction rates in batch experiments and sediment columns. Toluene oxidation was increased five-fold as compared to bulk, non-colloidal ferrihydrite as electron acceptor. Furthermore, we developed a unique approach for custom-tailoring the subsurface mobility of these particles after being injected into a contaminant plume. In a field pilot application, we injected 18 m3 of an iron oxide nanoparticle solution into a BTEX contaminated aquifer with a maximum excess pressure as low as 0.2 bar. The applied suspension showed a superior subsurface mobility, creating a reactive zone of 4 m height (corresponding to the height of the confined aquifer) and 6 m in diameter. Subsequent monitoring of BTEX, microbial BTEX degradation metabolites, ferrous iron generation, stable isotopes fractionation, microbial populations, and methanogenesis demonstrated the strong impact of our approach. Mathematic processed X-ray diffractograms and FTIR spectra provided a semi-quantitatively estimate of the long-term fate of the iron oxide colloids in the aquifer. Potential environmental risks of the injection itself were monitored with

  4. Support for the initial attachment, growth and differentiation of MG-63 cells: a comparison between nano-size hydroxyapatite and micro-size hydroxyapatite in composites

    PubMed Central

    Filová, Elena; Suchý, Tomáš; Sucharda, Zbyněk; Šupová, Monika; Žaloudková, Margit; Balík, Karel; Lisá, Věra; Šlouf, Miroslav; Bačáková, Lucie

    2014-01-01

    Hydroxyapatite (HA) is considered to be a bioactive material that favorably influences the adhesion, growth, and osteogenic differentiation of osteoblasts. To optimize the cell response on the hydroxyapatite composite, it is desirable to assess the optimum concentration and also the optimum particle size. The aim of our study was to prepare composite materials made of polydimethylsiloxane, polyamide, and nano-sized (N) or micro-sized (M) HA, with an HA content of 0%, 2%, 5%, 10%, 15%, 20%, 25% (v/v) (referred to as N0–N25 or M0–M25), and to evaluate them in vitro in cultures with human osteoblast-like MG-63 cells. For clinical applications, fast osseointegration of the implant into the bone is essential. We observed the greatest initial cell adhesion on composites M10 and N5. Nano-sized HA supported cell growth, especially during the first 3 days of culture. On composites with micro-size HA (2%–15%), MG-63 cells reached the highest densities on day 7. Samples M20 and M25, however, were toxic for MG-63 cells, although these composites supported the production of osteocalcin in these cells. On N2, a higher concentration of osteopontin was found in MG-63 cells. For biomedical applications, the concentration range of 5%–15% (v/v) nano-size or micro-size HA seems to be optimum. PMID:25125978

  5. Microcapsules ejecting nanosized species into the environment.

    PubMed

    De Geest, Bruno G; McShane, Michael J; Demeester, Jo; De Smedt, Stefaan C; Hennink, Wim E

    2008-11-05

    In this communication we report on microcapsules which eject nanoparticles into the environment. The speed of the nanoparticles ejected in water is approximately 800-fold faster than their Brownian diffusion. Such microcarriers may allow nanosized species to travel long distances, in short times, through highly viscous environments and may find applications in e.g. drug delivery and tissue engineering.

  6. Chemoprotective and chemosensitizing properties of selenium nanoparticle (Nano-Se) during adjuvant therapy with cyclophosphamide in tumor-bearing mice.

    PubMed

    Bhattacharjee, Arin; Basu, Abhishek; Biswas, Jaydip; Sen, Tuhinadri; Bhattacharya, Sudin

    2017-01-01

    Cyclophosphamide (CP) is one of the widely used anticancer agents; however, it has serious deleterious effects on normal host cells due to its nonspecific action. The essential trace element Selenium (Se) is suggested to have chemopreventive and chemotherapeutic efficacy and currently used in pharmaceutical formulations. Previous report had shown Nano-Se could protect CP-induced hepatotoxicity and genotoxicity in normal Swiss albino mice; however, its role in cancer management is still not clear. The aim of present study is to investigate the chemoprotective efficacy of Nano-Se against CP-induced toxicity as well as its chemoenhancing capability when used along with CP in Swiss albino mice against Ehrlich's ascites carcinoma (EAC) cells. CP was administered (25 mg/kg b.w., i.p.) and Nano-Se was given (2 mg Se/kg b.w., p.o.) in concomitant and pretreatment schedule. Increase levels of serum hepatic marker, hepatic lipid peroxidation, DNA damage, and chromosomal aberration in CP-treated mice were significantly (P < 0.05) reversed by Nano-Se. The lowered status of various antioxidant enzymes in tumor-bearing mice after CP treatment was also effectively increased by Nano-Se. Administration of Nano-Se along with CP caused a significant reduction in tumor volume, packed cell volume, viable tumor cell count, and increased the survivability of the tumor-bearing hosts. The results suggest that Nano-Se exhibits significant antitumor and antioxidant effects in EAC-bearing mice. The potential for Nano-Se to ameliorate the CP-evoked toxicity as well as to improve the chemotherapeutic effect could have beneficial implications for patients undergoing chemotherapy with CP.

  7. Sol-gel processing with inorganic metal salt precursors

    DOEpatents

    Hu, Zhong-Cheng

    2004-10-19

    Methods for sol-gel processing that generally involve mixing together an inorganic metal salt, water, and a water miscible alcohol or other organic solvent, at room temperature with a macromolecular dispersant material, such as hydroxypropyl cellulose (HPC) added. The resulting homogenous solution is incubated at a desired temperature and time to result in a desired product. The methods enable production of high quality sols and gels at lower temperatures than standard methods. The methods enable production of nanosize sols from inorganic metal salts. The methods offer sol-gel processing from inorganic metal salts.

  8. Donor and host photoreceptors engage in material transfer following transplantation of post-mitotic photoreceptor precursors

    PubMed Central

    Pearson, R. A.; Gonzalez-Cordero, A.; West, E. L.; Ribeiro, J. R.; Aghaizu, N.; Goh, D.; Sampson, R. D.; Georgiadis, A.; Waldron, P. V.; Duran, Y.; Naeem, A.; Kloc, M.; Cristante, E.; Kruczek, K.; Warre-Cornish, K.; Sowden, J. C.; Smith, A. J.; Ali, R. R.

    2016-01-01

    Photoreceptor replacement by transplantation is proposed as a treatment for blindness. Transplantation of healthy photoreceptor precursor cells into diseased murine eyes leads to the presence of functional photoreceptors within host retinae that express an array of donor-specific proteins. The resulting improvement in visual function was understood to be due to donor cells integrating within host retinae. Here, however, we show that while integration occurs the majority of donor-reporter-labelled cells in the host arises as a result of material transfer between donor and host photoreceptors. Material transfer does not involve permanent donor–host nuclear or cell–cell fusion, or the uptake of free protein or nucleic acid from the extracellular environment. Instead, RNA and/or protein are exchanged between donor and host cells in vivo. These data require a re-evaluation of the mechanisms underlying rescue by photoreceptor transplantation and raise the possibility of material transfer as a strategy for the treatment of retinal disorders. PMID:27701378

  9. High-Solids Polyimide Precursor Solutions

    NASA Technical Reports Server (NTRS)

    Chuang, Chun-Hua (Inventor)

    2004-01-01

    The invention is a highly concentrated stable solution of polymide precursors (monometers) having a solids content ranging from about 80 to 98 percent by weight in lower aliphatic alcohols i.e. methyl and/or ethylalcohol. the concentrated polyimide precursos solution comparisons effective amounts of at least one aromatic diamine, at least one aromatic dianhydride, and a monofunctional endcap including monoamines, monoanhydrides and lower alkyl esters of said monoanhydrides. These concentrated polyimide precursor solutions are particularly useful for the preparation of fibrous prepregs and composites for use in structural materials for military and civil applications.

  10. Characteristics and properties of nano-LiCoO2 synthesized by pre-organized single source precursors: Li-ion diffusivity, electrochemistry and biological assessment.

    PubMed

    Brog, Jean-Pierre; Crochet, Aurélien; Seydoux, Joël; Clift, Martin J D; Baichette, Benoît; Maharajan, Sivarajakumar; Barosova, Hana; Brodard, Pierre; Spodaryk, Mariana; Züttel, Andreas; Rothen-Rutishauser, Barbara; Kwon, Nam Hee; Fromm, Katharina M

    2017-08-22

    LiCoO 2 is one of the most used cathode materials in Li-ion batteries. Its conventional synthesis requires high temperature (>800 °C) and long heating time (>24 h) to obtain the micronscale rhombohedral layered high-temperature phase of LiCoO 2 (HT-LCO). Nanoscale HT-LCO is of interest to improve the battery performance as the lithium (Li + ) ion pathway is expected to be shorter in nanoparticles as compared to micron sized ones. Since batteries typically get recycled, the exposure to nanoparticles during this process needs to be evaluated. Several new single source precursors containing lithium (Li + ) and cobalt (Co 2+ ) ions, based on alkoxides and aryloxides have been structurally characterized and were thermally transformed into nanoscale HT-LCO at 450 °C within few hours. The size of the nanoparticles depends on the precursor, determining the electrochemical performance. The Li-ion diffusion coefficients of our LiCoO 2 nanoparticles improved at least by a factor of 10 compared to commercial one, while showing good reversibility upon charging and discharging. The hazard of occupational exposure to nanoparticles during battery recycling was investigated with an in vitro multicellular lung model. Our heterobimetallic single source precursors allow to dramatically reduce the production temperature and time for HT-LCO. The obtained nanoparticles of LiCoO 2 have faster kinetics for Li + insertion/extraction compared to microparticles. Overall, nano-sized LiCoO 2 particles indicate a lower cytotoxic and (pro-)inflammogenic potential in vitro compared to their micron-sized counterparts. However, nanoparticles aggregate in air and behave partially like microparticles.

  11. A Novel Approach of Using Ground CNTs as the Carbon Source to Fabricate Uniformly Distributed Nano-Sized TiCx/2009Al Composites

    PubMed Central

    Wang, Lei; Qiu, Feng; Ouyang, Licheng; Wang, Huiyuan; Zha, Min; Shu, Shili; Zhao, Qinglong; Jiang, Qichuan

    2015-01-01

    Nano-sized TiCx/2009Al composites (with 5, 7, and 9 vol% TiCx) were fabricated via the combustion synthesis of the 2009Al-Ti-CNTs system combined with vacuum hot pressing followed by hot extrusion. In the present study, CNTs were used as the carbon source to synthesize nano-sized TiCx particles. An attempt was made to correlate the effect of ground CNTs by milling and the distribution of synthesized nano-sized TiCx particles in 2009Al as well as the tensile properties of nano-sized TiCx/2009Al composites. Microstructure analysis showed that when ground CNTs were used, the synthesized nano-sized TiCx particles dispersed more uniformly in the 2009Al matrix. Moreover, when 2 h-milled CNTs were used, the 5, 7, and 9 vol% nano-sized TiCx/2009Al composites had the highest tensile properties, especially, the 9 vol% nano-sized TiCx/2009Al composites. The results offered a new approach to improve the distribution of in situ nano-sized TiCx particles and tensile properties of composites. PMID:28793749

  12. Nitrogen-Functionalized Hydrothermal Carbon Materials by Using Urotropine as the Nitrogen Precursor.

    PubMed

    Straten, Jan Willem; Schleker, Philipp; Krasowska, Małgorzata; Veroutis, Emmanouil; Granwehr, Josef; Auer, Alexander A; Hetaba, Walid; Becker, Sylvia; Schlögl, Robert; Heumann, Saskia

    2018-03-25

    Nitrogen-containing hydrothermal carbon (N-HTC) materials of spherical particle morphology were prepared by means of hydrothermal synthesis with glucose and urotropine as precursors. The molar ratio of glucose to urotropine has been varied to achieve a continuous increase in nitrogen content. By raising the ratio of urotropine to glucose, a maximal nitrogen fraction of about 19 wt % could be obtained. Decomposition products of both glucose and urotropine react with each other; this opens up a variety of possible reaction pathways. The pH has a pronounced effect on the reaction pathway of the corresponding reaction steps. For the first time, a comprehensive analytical investigation, comprising a multitude of analytical tools and instruments, of a series of nitrogen-containing HTC materials was applied. Functional groups and structural motifs identified were analyzed by means of FTIR spectroscopy, thermogravimetric MS, and solid-state NMR spectroscopy. Information on reaction mechanisms and structural details were obtained by electronic structure calculations that were compared with vibrational spectra of polyfuran or polypyrrole-like groups, which represent structural motifs occurring in the present samples. © 2018 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  13. Preparation of boron nitride fiber by organic precursor method

    NASA Astrophysics Data System (ADS)

    Zhou, Yingying; Sun, Runjun; Zhang, Zhaohuan; Fan, Wei; Zhou, Dan; Sheng, Cuihong

    In this paper, boron nitride polymer precursor was made by boric acid, melamine, twelve sodium alkyl sulfate as raw materials and pure water as medium which is heated to 70 °C. Boron nitride precursor polymer was soluble in formic acid solution. The boron nitride precursor can be electrostatically spun at the voltage in 23 kV and the distance between the positive and negative poles is 15 cm. The formed fiber is very uniform. The properties of the precursors were analyzed through electron microscope, infrared spectrum, X-ray and ultraviolet spectrum. The aim of the job is to got the precursor of BN and spun it.

  14. Nano-sized Ni-doped carbon aerogel for supercapacitor.

    PubMed

    Lee, Yoon Jae; Jung, Ji Chul; Park, Sunyoung; Seo, Jeong Gil; Baeck, Sung-Hyeon; Yoon, Jung Rag; Yi, Jongheop; Song, In Kyu

    2011-07-01

    Carbon aerogel was prepared by polycondensation of resorcinol with formaldehyde using sodium carbonate as a catalyst in ambient conditions. Nano-sized Ni-doped carbon aerogel was then prepared by a precipitation method in an ethanol solvent. In order to elucidate the effect of nickel content on electrochemical properties, Ni-doped carbon aerogels (21, 35, 60, and 82 wt%) were prepared and their performance for supercapacitor electrode was investigated. Electrochemical properties of Ni-doped carbon aerogel electrodes were measured by cyclic voltammetry at a scan rate of 10 mV/sec and charge/discharge test at constant current of 1 A/g in 6 M KOH electrolyte. Among the samples prepared, 35 wt% Ni-doped carbon aerogel (Ni/CA-35) showed the highest capacitance (110 F/g) and excellent charge/discharge behavior. The enhanced capacitance of Ni-doped carbon aerogel was attributed to the faradaic redox reactions of nano-sized nickel oxide. Moreover, Ni-doped carbon aerogel exhibited quite stable cyclability, indicating long-term electrochemical stability.

  15. Effect of nano-sized, elemental selenium supplement on the proteome of chicken liver.

    PubMed

    Gulyas, G; Csosz, E; Prokisch, J; Javor, A; Mezes, M; Erdelyi, M; Balogh, K; Janaky, T; Szabo, Z; Simon, A; Czegledi, L

    2017-06-01

    The nano-sized (100-500 nm) selenium has higher bioavailability and relatively lower toxicity compared to other selenium forms. The objective of the present study was to compare liver proteome profiles of broiler chicken fed with control diet without Se supplementation and diet supplemented with nano-Se with 4.25 mg/kg DM. Differential proteome analyses were performed by two-dimensional gel electrophoresis (2D-PAGE) followed by tryptic digestion and protein identification by liquid chromatography-mass spectrometry (LC-MS). Seven hundred and eight spots were detected, and 18 protein spots showed significant difference in their intensity (p < 0.05) between the two groups. In response to nano-Se supplementation, the expression of 8 proteins was higher, and 5 proteins were lower in nano-Se supplemented group compared to control group. The functions of the differentially expressed proteins indicate that the high dose of selenium supplementation induced a dietary stress. Selenium supplementation may influence the metabolism of fatty acids and carbohydrates and antioxidant system, and increase the quantity of cytoskeletal actin and the expression of actin regulatory protein as well. Journal of Animal Physiology and Animal Nutrition © 2016 Blackwell Verlag GmbH.

  16. A Novel Approach of Using Ground CNTs as the Carbon Source to Fabricate Uniformly Distributed Nano-Sized TiCx/2009Al Composites.

    PubMed

    Wang, Lei; Qiu, Feng; Ouyang, Licheng; Wang, Huiyuan; Zha, Min; Shu, Shili; Zhao, Qinglong; Jiang, Qichuan

    2015-12-17

    Nano-sized TiC x /2009Al composites (with 5, 7, and 9 vol% TiC x ) were fabricated via the combustion synthesis of the 2009Al-Ti-CNTs system combined with vacuum hot pressing followed by hot extrusion. In the present study, CNTs were used as the carbon source to synthesize nano-sized TiC x particles. An attempt was made to correlate the effect of ground CNTs by milling and the distribution of synthesized nano-sized TiC x particles in 2009Al as well as the tensile properties of nano-sized TiC x /2009Al composites. Microstructure analysis showed that when ground CNTs were used, the synthesized nano-sized TiC x particles dispersed more uniformly in the 2009Al matrix. Moreover, when 2 h-milled CNTs were used, the 5, 7, and 9 vol% nano-sized TiC x /2009Al composites had the highest tensile properties, especially, the 9 vol% nano-sized TiC x /2009Al composites. The results offered a new approach to improve the distribution of in situ nano-sized TiC x particles and tensile properties of composites.

  17. Magnetic glass-film based on single-nanosize 𝜺 -Fe2O3 nanoparticles

    NASA Astrophysics Data System (ADS)

    Yoshikiyo, Marie; Namai, Asuka; Nakagawa, Kosuke; Ohkoshi, Shin-ichi

    2017-05-01

    We report a magnetic thin film of single-nanosize ɛ-Fe2O3 in SiO2 matrix. The glass-film was prepared by sintering a silica coated iron oxide hydroxide on a quartz substrate in air. The glass-film consists of ɛ-Fe2O3 of 8.8 nm size, and its thickness was 570 nm (0.57 μm) with a roughness of 10 nm (0.01 μm). UV-vis spectrum showed that the glass-film has small absorbance of 0.043 at 500 nm. The magneto-optical effect was investigated, and Faraday ellipticity showed a magnetic hysteresis loop with a coercive field of 3.0 ± 0.2 kOe. Furthermore, single-nanosize ɛ-Fe2O3 without silica was prepared as a reference sample, and ferroelectricity was observed. Therefore, the present thin glass-film consists of single-nanosize ferroelectric-ferromagnetic nanoparticles.

  18. Size effect of elemental selenium nanoparticles (Nano-Se) at supranutritional levels on selenium accumulation and glutathione S-transferase activity.

    PubMed

    Peng, Dungeng; Zhang, Jinsong; Liu, Qingliang; Taylor, Ethan Will

    2007-10-01

    It has been shown that 36 nm Nano-Se has lower toxicity than selenite or selenomethionine, but these forms of selenium (Se) all possess similar ability to increase selenoenzyme levels. The size of nanoparticles plays an important role in their biological activity: as expected, 5-200 nm Nano-Se can directly scavenge free radicals in vitro in a size-dependent fashion. However, in Se-deficient cells and Se-deficient mice, the size effect of Nano-Se on increasing selenoenzymes and liver Se disappears unexpectedly. We hypothesize that under conditions of Se deficiency, the avidity of Se uptake mechanisms may be increased to maintain the biosynthesis of selenoenzymes, which are fundamental for redox homeostasis. This increased avidity may override the potential advantage of small size Nano-Se seen under Se-replete conditions, thereby eliminating the size effect. Once selenoenzymes have been saturated, Se uptake mechanisms may downregulate; accordingly, the size effect of Nano-Se can then reappear. To test this hypothesis, Se-deficient mice were administered either 36 or 90 nm Nano-Se at supranutritional doses, in both a short-term model and a single-dose model. Under these conditions, Nano-Se showed a size effect on Se accumulation and glutathione S-transferase (GST) activity. A size effect of Nano-Se was found in 15 out of 18 total comparisons between sizes at the same dose and time in the two models. Furthermore, the magnitude of the size effect was more prominent on Se accumulation than on GST activity. GST is strictly regulated by transcriptional and translational mechanisms, so its increase in activity normally does not exceed 3-fold. In contrast, the homeostasis of Se accumulation is not as tightly controlled. In the present experiments, GST activity had reached or was approaching saturation, but liver Se was far below saturation. Therefore, our results strongly suggest that the saturation profile of the tested biomarker has an impact on the size effect of Nano-Se

  19. Synthesis and structures of metal chalcogenide precursors

    NASA Technical Reports Server (NTRS)

    Hepp, Aloysius F.; Duraj, Stan A.; Eckles, William E.; Andras, Maria T.

    1990-01-01

    The reactivity of early transition metal sandwich complexes with sulfur-rich molecules such as dithiocarboxylic acids was studied. Researchers recently initiated work on precursors to CuInSe2 and related chalcopyrite semiconductors. Th every high radiation tolerance and the high absorption coefficient of CuInSe2 makes this material extremely attractive for lightweight space solar cells. Their general approach in early transition metal chemistry, the reaction of low-valent metal complexes or metal powders with sulfur and selenium rich compounds, was extended to the synthesis of chalcopyrite precursors. Here, the researchers describe synthesis, structures, and and routes to single molecule precursors to metal chalcogenides.

  20. Wear Resistance of Austempered Ductile Iron with Nanosized Additives

    NASA Astrophysics Data System (ADS)

    Kaleicheva, J. K.; Mishev, V.

    2018-01-01

    The wear resistance, microstructure and mechanical properties of austempered ductile iron (ADI) with nanosized additives of cubic boron nitride cBN are investigated. Samples of ductile iron are put under austhempering at the following conditions: heating at 900°С, 1 h and isothermal retention at 280оС, 2 h and 380°С, 2 h with the aim to achieve a lower bainitic structure and an upper bainitic structure. The experimental wear testing of austempered ductile irons is performed in friction conditions of a fixed abrasive by a cinematic scheme „pin - disc” using an accelerated testing method and device. The microstructure of the ADI is investigated by metallographic and X-Ray analyses. The Vickers hardness testing and impact strength examination are carried out. The influence of the nanosized additives of cBN on the wear resistance, microstructure, impact strength and hardness of the ADI is investigated.

  1. Synthesis and electrochemical property of LiCoO 2 thin films composed of nanosize compounds synthesized via nanosheet restacking method

    NASA Astrophysics Data System (ADS)

    Quan, Zhen; Iwase, Kosuke; Sonoyama, Noriyuki

    LiCoO 2 thin films with nanosize particles were synthesized on Au substrates by nanosheet restacking method and subsequent hydrothermal reaction which needs less cost than the vacuum deposition methods. The grain size of LiCoO 2 films estimated by XRD reflection was about 15 nm that was independent of the thickness of precursor cobalt hydroxide film. Comparing the rate performance of the thin films with various thickness, the optimum performance was obtained by the thin film with 5 min deposition time: 62% of the capacity was held at 400 C-rate compared with that at 20 C-rate. The results of AC-impedance analysis of electrode reaction indicate that the high rate capability of the LiCoO 2 film is obtained by the small grain size and large surface area of LiCoO 2 thin film with nano size particles.

  2. Spray Chemical Vapor Deposition of Single-Source Precursors for Chalcopyrite I-III-VI2 Thin-Film Materials

    NASA Technical Reports Server (NTRS)

    Hepp, Aloysius F.; Banger, Kulbinder K.; Jin, Michael H.-C.; Harris, Jerry D.; McNatt, Jeremiah S.; Dickman, John E.

    2008-01-01

    Thin-film solar cells on flexible, lightweight, space-qualified substrates provide an attractive approach to fabricating solar arrays with high mass-specific power. A polycrystalline chalcopyrite absorber layer is among the new generation of photovoltaic device technologies for thin film solar cells. At NASA Glenn Research Center we have focused on the development of new single-source precursors (SSPs) for deposition of semiconducting chalcopyrite materials onto lightweight, flexible substrates. We describe the syntheses and thermal modulation of SSPs via molecular engineering. Copper indium disulfide and related thin-film materials were deposited via aerosol-assisted chemical vapor deposition using SSPs. Processing and post-processing parameters were varied in order to modify morphology, stoichiometry, crystallography, electrical properties, and optical properties to optimize device quality. Growth at atmospheric pressure in a horizontal hotwall reactor at 395 C yielded the best device films. Placing the susceptor closer to the evaporation zone and flowing a more precursor-rich carrier gas through the reactor yielded shinier-, smoother-, and denser-looking films. Growth of (112)-oriented films yielded more Cu-rich films with fewer secondary phases than growth of (204)/(220)-oriented films. Post-deposition sulfur-vapor annealing enhanced stoichiometry and crystallinity of the films. Photoluminescence studies revealed four major emission bands and a broad band associated with deep defects. The highest device efficiency for an aerosol-assisted chemical vapor deposited cell was one percent.

  3. The dispersion releaser technology is an effective method for testing drug release from nanosized drug carriers.

    PubMed

    Janas, Christine; Mast, Marc-Phillip; Kirsamer, Li; Angioni, Carlo; Gao, Fiona; Mäntele, Werner; Dressman, Jennifer; Wacker, Matthias G

    2017-06-01

    The dispersion releaser (DR) is a dialysis-based setup for the analysis of the drug release from nanosized drug carriers. It is mounted into dissolution apparatus2 of the United States Pharmacopoeia. The present study evaluated the DR technique investigating the drug release of the model compound flurbiprofen from drug solution and from nanoformulations composed of the drug and the polymer materials poly (lactic acid), poly (lactic-co-glycolic acid) or Eudragit®RSPO. The drug loaded nanocarriers ranged in size between 185.9 and 273.6nm and were characterized by a monomodal size distribution (PDI<0.1). The membrane permeability constants of flurbiprofen were calculated and mathematical modeling was applied to obtain the normalized drug release profiles. For comparing the sensitivities of the DR and the dialysis bag technique, the differences in the membrane permeation rates were calculated. Finally, different formulation designs of flurbiprofen were sensitively discriminated using the DR technology. The mechanism of drug release from the nanosized carriers was analyzed by applying two mathematical models described previously, the reciprocal powered time model and the three parameter model. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Emerging potential of stimulus-responsive nanosized anticancer drug delivery systems for systemic applications.

    PubMed

    Ruttala, Hima Bindu; Ramasamy, Thiruganesh; Madeshwaran, Thiagarajan; Hiep, Tran Tuan; Kandasamy, Umadevi; Oh, Kyung Taek; Choi, Han-Gon; Yong, Chul Soon; Kim, Jong Oh

    2018-02-01

    The development of novel drug delivery systems based on well-defined polymer therapeutics has led to significant improvements in the treatment of multiple disorders. Advances in material chemistry, nanotechnology, and nanomedicine have revolutionized the practices of drug delivery. Stimulus-responsive material-based nanosized drug delivery systems have remarkable properties that allow them to circumvent biological barriers and achieve targeted intracellular drug delivery. Specifically, the development of novel nanocarrier-based therapeutics is the need of the hour in managing complex diseases. In this review, we have briefly described the fundamentals of drug targeting to diseased tissues, physiological barriers in the human body, and the mechanisms/modes of drug-loaded carrier systems. To that end, this review serves as a comprehensive overview of the recent developments in stimulus-responsive drug delivery systems, with focus on their potential applications and impact on the future of drug delivery.

  5. Functionally charged nanosize particles differentially activate BV2 microglia.

    EPA Science Inventory

    The effect of particle surface charge on the biological activation of immortalized mouse microglia (BV2) was examined. Nanosize (860-950 nm) spherical polystyrene microparticles (SPM) were coated with carboxyl (COOH-) or dimethyl amino (CH3)2-N- groups to give a net negative or p...

  6. Effects of Precipitant and pH on Coprecipitation of Nanosized Co-Cr-V Alloy Powders.

    PubMed

    Chen, Xiaoyu; Li, Yongxia; Huang, Lan; Zou, Dan; Wu, Enxi; Liu, Yanjun; Xie, Yuanyan; Yao, Rui; Liao, Songyi; Wang, Guangrong; Zheng, Feng

    2017-09-21

    Nanosized Co-Cr-V alloy powders were synthesized via coprecipitation method. Effects of precipitants ((NH₄)₂C₂O₄·H₂O and Na₂CO₃) and pH were investigated by X-ray diffraction (XRD), Zeta potential analyzer, thermogravimetry-differential scanning calorimetry (TG-DSC), inductively coupled plasma-atomic emission spectrometry (ICP-AES) and scanning electron microscopy (SEM). Co-Cr-V alloy powders were consisted of major face-centered cubic Co (fcc Co) and minor hexagonal close-packed Co (hcp Co). Grain sizes of precursors and Co-Cr-V alloy powders were increased with pH value (7-10) within the ranges of 3~39 and 39~66 nm, respectively. Rod-like or granular Co-Cr-V alloy particles were assembled by interconnected nanograins. At pH = 7, Na₂CO₃ precipitant was found to be beneficial to maintain the desirable composition of Co-Cr-V powders. It was also found that lower pH favors the maintenance of pre-designed composition, while grain coarsens at higher pH. Effects of variation for precipitant and pH on the morphology and composition of Co-Cr-V alloy powder were discussed in detail and relevant mechanism was further proposed.

  7. Green synthesis of nanocrystalline α-Al2O3 powders by both wet-chemical and mechanochemical methods

    NASA Astrophysics Data System (ADS)

    Gao, Huiying; Li, Zhiyong; Zhao, Peng

    2018-03-01

    Nanosized α-Al2O3 powders were prepared with AlCl3ṡ6H2O and NH4HCO3 as raw materials by both wet-chemical and mechanochemical methods, through the synthesis of the ammonium aluminum carbonate hydroxide (AACH) precursor followed by calcination. The environmentally benign starch was used as an effective dispersant during the preparation of nanocrystalline α-Al2O3 powders. X-ray diffraction (XRD), thermogravimetric differential thermal analysis (TG-DTA), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were employed to characterize the precursor AACH and products. The results show that nanosized spherical α-Al2O3 powders without hard agglomeration and with particle size in the range of 20-40 nm can be obtained by the two methods. Comparing the two “green” processes, the mechanochemical method has better prospects for commercial production.

  8. De-agglomeration and homogenisation of nanoparticles in coal tar pitch-based carbon materials

    NASA Astrophysics Data System (ADS)

    Gubernat, Maciej; Tomala, Janusz; Frohs, Wilhelm; Fraczek-Szczypta, Aneta; Blazewicz, Stanislaw

    2016-03-01

    The aim of the work was to characterise coal tar pitch (CTP) modified with selected nanoparticles as a binder precursor for the manufacture of synthetic carbon materials. Different factors influencing the preliminary preparative steps in the preparation of homogenous nanoparticle/CTP composition were studied. Graphene flakes, carbon black and nano-sized silicon carbide were used to modify CTP. Prior to introducing them into liquid CTP, nanoparticles were subjected to sonication. Various dispersants were used to prepare the suspensions, i.e. water, ethanol, dimethylformamide (DMF) and N-methylpyrrolidone (NMP).The results showed that proper dispersant selection is one of the most important factors influencing the de-agglomeration process of nanoparticles. DMF and NMP were found to be effective dispersants for the preparation of homogenous nanoparticle-containing suspensions. The presence of SiC and carbon black nanoparticles in the liquid pitch during heat treatment up to 2000 °C leads to the inhibition of crystallite growth in carbon residue.

  9. Characterization of nano-sized oxides in Fe-12Cr oxide-dispersion-strengthened ferritic steel using small-angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Han, Young-Soo; Mao, Xiaodong; Jang, Jinsung; Kim, Tae-Kyu

    2015-04-01

    The ferritic ODS steel was manufactured by hot isostatic pressing and heat treatment. The nano-sized microstructures such as yttrium oxides and Cr oxides were quantitatively analyzed by small-angle neutron scattering (SANS). The effects of the fabrication conditions on the nano-sized microstructure were investigated in relation to the quantitative analysis results obtained by SANS. The ratio between magnetic and nuclear scattering components was calculated, and the characteristics of the nano-sized yttrium oxides are discussed based on the SANS analysis results.

  10. Benzimidazole Based Aerogel Materials

    NASA Technical Reports Server (NTRS)

    Rhine, Wendell E. (Inventor); Mihalcik, David (Inventor)

    2016-01-01

    The present invention provides aerogel materials based on imidazoles and polyimidazoles. The polyimidazole based aerogel materials can be thermally stable up to 500 C or more, and can be carbonized to produce a carbon aerogel having a char yield of 60% or more, specifically 70% or more. The present invention also provides methods of producing polyimidazole based aerogel materials by reacting at least one monomer in a suitable solvent to form a polybenzimidazole gel precursor solution, casting the polybenzimidazole gel precursor solution into a fiber reinforcement phase, allowing the at least one gel precursor in the precursor solution to transition into a gel material, and drying the gel materials to remove at least a portion of the solvent, to obtain an polybenzimidazole-based aerogel material.

  11. Mesoporous carbon materials

    DOEpatents

    Dai, Sheng [Knoxville, TN; Wang, Xiqing [Oak Ridge, TN

    2012-02-14

    The invention is directed to a method for fabricating a mesoporous carbon material, the method comprising subjecting a precursor composition to a curing step followed by a carbonization step, the precursor composition comprising: (i) a templating component comprised of a block copolymer, (ii) a phenolic compound or material, (iii) a crosslinkable aldehyde component, and (iv) at least 0.5 M concentration of a strong acid having a pKa of or less than -2, wherein said carbonization step comprises heating the precursor composition at a carbonizing temperature for sufficient time to convert the precursor composition to a mesoporous carbon material. The invention is also directed to a mesoporous carbon material having an improved thermal stability, preferably produced according to the above method.

  12. Mesoporous carbon materials

    DOEpatents

    Dai, Sheng; Wang, Xiqing

    2013-08-20

    The invention is directed to a method for fabricating a mesoporous carbon material, the method comprising subjecting a precursor composition to a curing step followed by a carbonization step, the precursor composition comprising: (i) a templating component comprised of a block copolymer, (ii) a phenolic compound or material, (iii) a crosslinkable aldehyde component, and (iv) at least 0.5 M concentration of a strong acid having a pKa of or less than -2, wherein said carbonization step comprises heating the precursor composition at a carbonizing temperature for sufficient time to convert the precursor composition to a mesoporous carbon material. The invention is also directed to a mesoporous carbon material having an improved thermal stability, preferably produced according to the above method.

  13. Nano-sized Fe2O3/Fe3O4 facilitate anaerobic transformation of hexavalent chromium in soil-water systems.

    PubMed

    Zhang, Yaxian; Li, Hua; Gong, Libo; Dong, Guowen; Shen, Liang; Wang, Yuanpeng; Li, Qingbiao

    2017-07-01

    The purpose of this study is to investigate the effects of nano-sized or submicro Fe 2 O 3 /Fe 3 O 4 on the bioreduction of hexavalent chromium (Cr(VI)) and to evaluate the effects of nano-sized Fe 2 O 3 /Fe 3 O 4 on the microbial communities from the anaerobic flooding soil. The results indicated that the net decreases upon Cr(VI) concentration from biotic soil samples amended with nano-sized Fe 2 O 3 (317.1±2.1mg/L) and Fe 3 O 4 (324.0±22.2mg/L) within 21days, which were approximately 2-fold of Cr(VI) concentration released from blank control assays (117.1±5.6mg/L). Furthermore, the results of denaturing gradient gel electrophoresis (DGGE) and high-throughput sequencing indicated a greater variety of microbes within the microbial community in amendments with nano-sized Fe 2 O 3 /Fe 3 O 4 than the control assays. Especially, Proteobacteria occupied a predominant status on the phylum level within the indigenous microbial communities from chromium-contaminated soils. Besides, some partial decrease of soluble Cr(VI) in abiotic nano-sized Fe 2 O 3 /Fe 3 O 4 amendments was responsible for the adsorption of nano-sized Fe 2 O 3 /Fe 3 O 4 to soluble Cr(VI). Hence, the presence of nano-sized Fe 2 O 3 /Fe 3 O 4 could largely facilitate the mobilization and biotransformation of Cr(VI) from flooding soils by adsorption and bio-mediated processes. Copyright © 2017. Published by Elsevier B.V.

  14. Nanosized iron based permeable reactive barriers for nitrate removal - Systematic review

    NASA Astrophysics Data System (ADS)

    Araújo, Rui; Castro, Ana C. Meira; Santos Baptista, João; Fiúza, António

    2016-08-01

    It is unquestionable that an effective decision concerning the usage of a certain environmental clean-up technology should be conveniently supported. Significant amount of scientific work focussing on the reduction of nitrate concentration in drinking water by both metallic iron and nanomaterials and their usage in permeable reactive barriers has been worldwide published over the last two decades. This work aims to present in a systematic review of the most relevant research done on the removal of nitrate from groundwater using nanosized iron based permeable reactive barriers. The research was based on scientific papers published between 2004 and June 2014. It was performed using 16 combinations of keywords in 34 databases, according to PRISMA statement guidelines. Independent reviewers validated the selection criteria. From the 4161 records filtered, 45 met the selection criteria and were selected to be included in this review. This study's outcomes show that the permeable reactive barriers are, indeed, a suitable technology for denitrification and with good performance record but the long-term impact of the use of nanosized zero valent iron in this remediation process, in both on the environment and on the human health, is far to be conveniently known. As a consequence, further work is required on this matter, so that nanosized iron based permeable reactive barriers for the removal of nitrate from drinking water can be genuinely considered an eco-efficient technology.

  15. Poly(diiododiacetylene): A Potential Precursor for New All-Carbon Materials

    NASA Astrophysics Data System (ADS)

    Resch, Daniel Joseph

    Poly(diiododiacetylene) (PIDA) is a polymer consisting entirely of carbon and iodine. The polymer is prepared by cocrystallizing a bis(nitrile) oxalamide host with the monomer diiodobutadiyne. These compounds are held together by a halogen bond and an ordered 1,4-topochemical polymerization occurs in the solid state. The formation of the monomer cocrystals was found to be highly solvent dependent. Acetonitrile was found to greatly improve the yield of cocrystals over solvents used in the past. Cocrystals could not be obtained from other solvents such as dimethoxyethane and acetone. THF did give some cocrystal but the yield was poor. The use of acetonitrile as a solvent now allows for PIDA cocrystals to be reliably prepared in excellent yield for detailed studies. The weak C-I bonds in PIDA can be broken under mild conditions with simple Lewis bases like pyrrolidine and iodide ion. Studies with small molecule models show that the mechanism of elimination is E2-like and highly solvent dependent. Polar aprotic solvents favor the reaction while non-polar solvents disfavor it. Reaction occurs in protic solvents, but the rate is much slower. Iodide was found to carry out the reaction in 1 hour d5-PhNO 2 while reaction with pyrrolidine did not reach completion in 15 hours. When PIDA is subjected to deiodination the product is an amorphous graphite-like material that contains non-carbon atoms. Depending on the reaction conditions, it is possible to incorporate sulfur or phosphorus into the final product. The source of these elements is the reducing agent that is typically added to sequester molecular iodine. Sequestering the iodine prevents it from reacting with the carbon species. New insights into the deiodination reaction have made PIDA more promising as a precursor to prepare all-carbon materials or heteroatom-functionalized carbon under mild conditions.

  16. New precursors for direct synthesis of single phase Na- and K-{beta}{double_prime}-aluminas for use in AMTEC systems

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cook, R.L.; MacQueen, D.B.; Bader, K.E.

    1997-12-31

    Alkali Metal Thermoelectric Converters (AMTEC) are efficient direct energy conversion devices that depend on the use of highly conductive beta-alumina membranes for their operation. The key component of the AMTEC system is a highly conductive Na-{beta}{double_prime}-alumina solid electrolyte which conducts sodium ions from the high to low temperature zone, thereby generating electricity. AMTEC cells convert thermal to electrical energy by using heat to produce and maintain an alkali metal concentration gradient across the ion transporting BASE membrane. They have developed a method for producing pure phase Na-{beta}{double_prime}-alumina and K-{beta}{double_prime}-alumina powders from single phase nano-sized carboxylato-alumoxanes precursors. Sodium or potassium ionsmore » (the mobile ions) and either Mg{sup 2+} or Li{sup +} ions (which stabilize the {beta}{double_prime}-alumina structure) can be atomically dispersed into the carboxylato-alumoxane lattice at low (< 100 C) temperature. Calculation of the carboxylato-alumoxane precursors at 1,200--1,500 C produces pure phase {beta}{double_prime}-alumina powders.« less

  17. Nano-Sized Grain Refinement Using Friction Stir Processing

    DTIC Science & Technology

    2013-03-01

    friction stir weld is a very fine grain microstructure produced as a result of dynamic recrystallization. The friction stir ... Friction Stir Processing, Magnesium, Nano-size grains Abstract A key characteristic of a friction stir weld is a very fine grain microstructure...state process developed on the basis of the friction stir welding (FSW) technique invented by The Welding Institute (TWI) in 1991 [2]. During

  18. Coated electroactive materials

    DOEpatents

    Amine, Khalil; Abouimrane, Ali

    2016-08-30

    A process includes suspending an electroactive material in a solvent, suspending or dissolving a carbon precursor in the solvent; and depositing the carbon precursor on the electroactive material to form a carbon-coated electroactive material. Compositions include a graphene-coated electroactive material prepared from a solution phase mixture or suspension of an electroactive material and graphene, graphene oxide, or a mixture thereof.

  19. In vitro toxicity test of nano-sized magnesium oxide synthesized via solid-phase transformation

    NASA Astrophysics Data System (ADS)

    Zheng, Jun; Zhou, Wei

    2018-04-01

    Nano-sized magnesium oxide (MgO) has been a promising potential material for biomedical pharmaceuticals. In the present investigation, MgO nanoparticles synthesized through in-situ solid-phase transformation based on the previous work (nano-Mg(OH)2 prepared by precipitation technique) using magnesium nitrate and sodium hydroxide. The phase structure and morphology of the MgO nanoparticles are characterized by X-ray powder diffraction (XRD), selected area electronic diffraction (SAED) and transmission electron microscopy (TEM) respectively. In vitro hemolysis tests are adopted to evaluate the toxicity of the synthesized nano-MgO. The results evident that nano-MgO with lower concentration is slightly hemolytic, and with concentration increasing nano-MgO exhibit dose-responsive hemolysis.

  20. Nanosized aerosols from consumer sprays: experimental analysis and exposure modeling for four commercial products

    NASA Astrophysics Data System (ADS)

    Lorenz, Christiane; Hagendorfer, Harald; von Goetz, Natalie; Kaegi, Ralf; Gehrig, Robert; Ulrich, Andrea; Scheringer, Martin; Hungerbühler, Konrad

    2011-08-01

    Consumer spray products are already on the market in the cosmetics and household sector, which suggest by their label that they contain engineered nanoparticles (ENP). Sprays are considered critical for human health, because the lungs represent a major route for the uptake of ENP into the human body. To contribute to the exposure assessment of ENP in consumer spray products, we analyzed ENP in four commercially available sprays: one antiperspirant, two shoe impregnation sprays, and one plant-strengthening agent. The spray dispersions were analyzed by inductively coupled plasma mass spectrometry (ICPMS) and (scanning-) transmission electron microscopy ((S)TEM). Aerosols were generated by using the original vessels, and analyzed by scanning mobility particle sizer (SMPS) and (S)TEM. On the basis of SMPS results, the nanosized aerosol depositing in the respiratory tract was modeled for female and male consumers. The derived exposure levels reflect a single spray application. We identified ENP in the dispersions of two products (shoe impregnation and plant spray). Nanosized aerosols were observed in three products that contained propellant gas. The aerosol number concentration increased linearly with the sprayed amount, with the highest concentration resulting from the antiperspirant. Modeled aerosol exposure levels were in the range of 1010 nanosized aerosol components per person and application event for the antiperspirant and the impregnation sprays, with the largest fraction of nanosized aerosol depositing in the alveolar region. Negligible exposure from the application of the plant spray (pump spray) was observed.

  1. Investigation of nanosized crystalline form to improve the oral bioavailability of poorly water soluble cilostazol.

    PubMed

    Miao, Xiaoqing; Sun, Changshan; Jiang, Tongying; Zheng, Li; Wang, Tianyi; Wang, Siling

    2011-01-01

    The aim of this study was to develop cilostazol (CLT) nanocrystals intended to improve its dissolution rate and enhance its bioavailability. In this study, CLT nanosuspension was prepared by the anti-solvent and high-pressure homogenization method. The effects of the production parameters, such as the stabilizer concentration, pressure and number of cycles, were investigated. Characterization of the product was performed by scanning electron microscopy (SEM), Nitrogen adsorption, differential scanning calorimetry (DSC), X-ray powder diffraction analysis (XRPD), X-ray Photoelectron Spectroscopy (XPS), particle size analysis and dissolution testing. Additionally, the comparison studies of oral bioavailability in beagle dogs of three type tables were performed. The images of SEM showed a spherical smooth CLT powder, and Nitrogen adsorption test revealed spray dried powder were porous with high BET surface area compared with that of raw CLT. DSC and XRPD results demonstrated that the combination of preferred polymorph B and C of CLT were prepared successfully, the saturation solubility of the nanosized crystalline powder is about 5 fold greater than that of raw CLT, and the dissolution rate was enhanced 4 fold than that of raw CLT. The Cmax and AUC0-48h of CLT nanosized crystalline tablets were 2.1 fold and 1.9 fold, and 3.0 fold and 2.3 fold compared with those of the nanosized tablets and commercial tablets, respectively. The anti-solvent-high-pressure homogenization technique was employed successfully to produce cilostazol nanosuspensions. The bioavailability of CLT tablets prepared using spray dried nanosized crystalline powder after oral administration to dogs was markedly increased compared with that produced by nanosized tablets and commercial tablets, because of its greater dissolution rate owing to its transition of the crystalline state to form C and form B, reduced particle size and porous structure with increased surface area.

  2. Dry Process for Manufacturing Hybridized Boron Fiber/Carbon Fiber Thermoplastic Composite Materials from a Solution Coated Precursor

    NASA Technical Reports Server (NTRS)

    Belvin, Harry L. (Inventor); Cano, Roberto J. (Inventor)

    2003-01-01

    An apparatus for producing a hybrid boron reinforced polymer matrix composite from precursor tape and a linear array of boron fibers. The boron fibers are applied onto the precursor tapes and the precursor tape processed within a processing component having an impregnation bar assembly. After passing through variable-dimension forming nip-rollers, the precursor tape with the boron fibers becomes a hybrid boron reinforced polymer matrix composite. A driving mechanism is used to pulled the precursor tape through the method and a take-up spool is used to collect the formed hybrid boron reinforced polymer matrix composite.

  3. Porous carbon materials synthesized using IRMOF-3 and furfuryl alcohol as precursor

    NASA Astrophysics Data System (ADS)

    Deka, Pemta Tia; Ediati, Ratna

    2016-03-01

    IRMOF-3 crystals have been synthesized using solvothermal method by adding zinc nitrate hexahydrate with 2-amino-1,4-benzenedicarboxylic acid in N'N-dimethylformamide (DMF) at 100°C for 24 (note as IR-24) and 72 h (note as IR-72). The obtained crystals were characterized using X-ray Diffraction (XRD), SEM (Scanning Electron Microscopy) and Scanning Electron Microscopy-Energy Dispersive X-ray (SEM-EDX), FTIR and Isothermal adsorption-desorption N2. The diffractogram solids synthesized show characteristic peak at 2θ 6.8, 9.6 and 13.7°. SEM micrograph show cubic shape of IRMOF-3 crystal. Based on FTIR characterization, IRMOF-3 appear at wavelength (1691,46; 1425,3; 1238,21; 1319,22 dan 3504,42)cm-1. The Isotherm of crystal IRMOF-3 at heating time 24 h and 72 h are type IV. The surface area of IR-24 and IR-72 are respectively 24,758 m2/g and 29,139 m2/g with its dominant mesopores. Carbonaceous materials has been successfully synthesized using IR-24, IR-72 and furfuryl alcohol (FA) as second carbon precursor with variation of carbonation temperature 550, 700 and 850°C. The XRD result from both carbonaceous materials show formation of amorphous carbon and caharacteristic peak of ZnO oxide. Micrograph SEM show that carbonaceous materials have cubic shape as IRMOF-3 and SEM-EDX result indicate Zn and nitrogen content of these materials has decrease until temperature 850°C. Porous carbon using IR-24 and FA (notes as C-24) has increased surface area with higher carbonation temperature. The highest surface area is 1495,023 m2/g. Total pore volume and pore size of C-24 from low to high temperature respectively as (0,338; 0,539 and 1,598) cc/g; (0,107; 0,152 and 0,610) cc/g. Porous carbon using IR-72 and FA (notes as C-72) has smaller surface area than C-24 but its also increased during higher carbonation heating. The highest surface area is 1029,668 m2/g.The total pore volume and pore size of these carbon materials from low to high temperature respectively as (0,390; 0

  4. Mid-Atomic-Number Cylindrical Wire Array Precursor Plasma Studies on Zebra

    DOE PAGES

    Stafford, A; Safronova, A. S.; Kantsyrev, V. L.; ...

    2014-12-30

    The precursor plasmas from low wire number cylindrical wire arrays (CWAs) were previously shown to radiate at temperatures >300 eV for Ni-60 (94% Cu and 6% Ni) wires in experiments on the 1-MA Zebra generator. Continued research into precursor plasmas has studied additional midatomic-number materials including Cu and Alumel (95% Ni, 2% Al, 2% Mn, and 1% Si) to determine if the >300 eV temperatures are common for midatomic-number materials. Additionally, current scaling effects were observed by performing CWA precursor experiments at an increased current of 1.5 MA using a load current multiplier. Our results show an increase in amore » linear radiation yield of ~50% (16 versus 10 kJ/cm) for the experiments at increased current. However, plasma conditions inferred through the modeling of X-ray time-gated spectra are very similar for the precursor plasma in both current conditions.« less

  5. Rapid screening and identification of improvised explosive and hazardous precursor materials by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Stokes, Robert J.; Smith, W. Ewen; Foulger, Brian; Lewis, Colin

    2008-10-01

    A low cost technique is reported for the rapid screening of containers for materials that potentially could be used for terrorist activities. For peroxide based samples it is demonstrated that full characterisation can be achieved in a continuous curve fitting monitoring mode acquiring up to 10 spectra per second. This clearly demonstrates the potential for a Raman based method to be incorporated into a check-point whilst retaining fast throughput. A number of precursor compounds to nerve agents and peroxide and nitrate based improvised explosive materials have been studied. The potential strengths and weaknesses of using Raman for multiple target identification are discussed with regard to the common vibrations associated with each group of agents. Within this context we also introduce the use of fast Raman line mapping into the trace analysis of multiple component targets. The method presented is suited to volatile or light sensitive samples (such as derived peroxides) and can be employed on a variety of surfaces. As speed and throughput are traded against spectral bandwidth categorising threat compounds into groups based on common functionalities allows the full potential for multiplexed targeting to be realised.

  6. Silicon deposition in nanopores using a liquid precursor.

    PubMed

    Masuda, Takashi; Tatsuda, Narihito; Yano, Kazuhisa; Shimoda, Tatsuya

    2016-11-22

    Techniques for depositing silicon into nanosized spaces are vital for the further scaling down of next-generation devices in the semiconductor industry. In this study, we filled silicon into 3.5-nm-diameter nanopores with an aspect ratio of 70 by exploiting thermodynamic behaviour based on the van der Waals energy of vaporized cyclopentasilane (CPS). We originally synthesized CPS as a liquid precursor for semiconducting silicon. Here we used CPS as a gas source in thermal chemical vapour deposition under atmospheric pressure because vaporized CPS can fill nanopores spontaneously. Our estimation of the free energy of CPS based on Lifshitz van der Waals theory clarified the filling mechanism, where CPS vapour in the nanopores readily undergoes capillary condensation because of its large molar volume compared to those of other vapours such as water, toluene, silane, and disilane. Consequently, a liquid-specific feature was observed during the deposition process; specifically, condensed CPS penetrated into the nanopores spontaneously via capillary force. The CPS that filled the nanopores was then transformed into solid silicon by thermal decomposition at 400 °C. The developed method is expected to be used as a nanoscale silicon filling technology, which is critical for the fabrication of future quantum scale silicon devices.

  7. Silicon deposition in nanopores using a liquid precursor

    NASA Astrophysics Data System (ADS)

    Masuda, Takashi; Tatsuda, Narihito; Yano, Kazuhisa; Shimoda, Tatsuya

    2016-11-01

    Techniques for depositing silicon into nanosized spaces are vital for the further scaling down of next-generation devices in the semiconductor industry. In this study, we filled silicon into 3.5-nm-diameter nanopores with an aspect ratio of 70 by exploiting thermodynamic behaviour based on the van der Waals energy of vaporized cyclopentasilane (CPS). We originally synthesized CPS as a liquid precursor for semiconducting silicon. Here we used CPS as a gas source in thermal chemical vapour deposition under atmospheric pressure because vaporized CPS can fill nanopores spontaneously. Our estimation of the free energy of CPS based on Lifshitz van der Waals theory clarified the filling mechanism, where CPS vapour in the nanopores readily undergoes capillary condensation because of its large molar volume compared to those of other vapours such as water, toluene, silane, and disilane. Consequently, a liquid-specific feature was observed during the deposition process; specifically, condensed CPS penetrated into the nanopores spontaneously via capillary force. The CPS that filled the nanopores was then transformed into solid silicon by thermal decomposition at 400 °C. The developed method is expected to be used as a nanoscale silicon filling technology, which is critical for the fabrication of future quantum scale silicon devices.

  8. Hydrogen storage properties of nanosized MgH2-0.1TiH2 prepared by ultrahigh-energy-high-pressure milling.

    PubMed

    Lu, Jun; Choi, Young Joon; Fang, Zhigang Zak; Sohn, Hong Yong; Rönnebro, Ewa

    2009-11-04

    Magnesium hydride (MgH(2)) is an attractive candidate for solid-state hydrogen storage applications. To improve the kinetics and thermodynamic properties of MgH(2) during dehydrogenation-rehydrogenation cycles, a nanostructured MgH(2)-0.1TiH(2) material system prepared by ultrahigh-energy-high-pressure mechanical milling was investigated. High-resolution transmission electron microscope (TEM) and scanning TEM analysis showed that the grain size of the milled MgH(2)-0.1TiH(2) powder is approximately 5-10 nm with uniform distributions of TiH(2) among MgH(2) particles. Pressure-composition-temperature (PCT) analysis demonstrated that both the nanosize and the addition of TiH(2) contributed to the significant improvement of the kinetics of dehydrogenation and hydrogenation compared to commercial MgH(2). More importantly, PCT cycle analysis demonstrated that the MgH(2)-0.1TiH(2) material system showed excellent cycle stability. The results also showed that the DeltaH value for the dehydrogenation of nanostructured MgH(2)-0.1TiH(2) is significantly lower than that of commercial MgH(2). However, the DeltaS value of the reaction was also lower, which results in minimum net effects of the nanosize and the addition of TiH(2) on the equilibrium pressure of dehydrogenation reaction of MgH(2).

  9. Strategy for chemotherapeutic delivery using a nanosized porous metal-organic framework with a central composite design

    PubMed Central

    Li, Yingpeng; Li, Xiuyan; Guan, Qingxia; Zhang, Chunjing; Xu, Ting; Dong, Yujing; Bai, Xinyu; Zhang, Weiping

    2017-01-01

    Background Enhancing drug delivery is an ongoing endeavor in pharmaceutics, especially when the efficacy of chemotherapy for cancer is concerned. In this study, we prepared and evaluated nanosized HKUST-1 (nanoHKUST-1), nanosized metal-organic drug delivery framework, loaded with 5-fluorouracil (5-FU) for potential use in cancer treatment. Materials and methods NanoHKUST-1 was prepared by reacting copper (II) acetate [Cu(OAc)2] and benzene-1,3,5-tricarboxylic acid (H3BTC) with benzoic acid (C6H5COOH) at room temperature (23.7°C±2.4°C). A central composite design was used to optimize 5-FU-loaded nanoHKUST-1. Contact time, ethanol concentration, and 5-FU:material ratios were the independent variables, and the entrapment efficiency of 5-FU was the response parameter measured. Powder X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption were used to determine the morphology of nanoHKUST-1. In addition, 5-FU release studies were conducted, and the in vitro cytotoxicity was evaluated. Results Entrapment efficiency and drug loading were 9.96% and 40.22%, respectively, while the small-angle X-ray diffraction patterns confirmed a regular porous structure. The SEM and TEM images of the nanoHKUST-1 confirmed the presence of round particles (diameter: approximately 100 nm) and regular polygon arrays of mesoporous channels of approximately 2–5 nm. The half-maximal lethal concentration (LC50) of the 5-FU-loaded nanoHKUST-1 was approximately 10 µg/mL. Conclusion The results indicated that nanoHKUST-1 is a potential vector worth developing as a cancer chemotherapeutic drug delivery system. PMID:28260892

  10. An insight into the influence of crystallite size on the performances of microsized spherical Li(Ni0.5Co0.2Mn0.3)O2 cathode material composed of aggregated nanosized particles

    NASA Astrophysics Data System (ADS)

    Fan, Guangxin; Wen, Yin; Liu, Baozhong; Yang, Wenpeng

    2018-02-01

    Relationships between the performance and the crystallite size of the microsized spherical Li(Ni0.5Co0.2Mn0.3)O2 cathode material composed of aggregated nanosized primary particles have been comprehensively studied. The cathode material was synthesized by a high-temperature solid-state method. The results obtained by XRD, Rietveld refinement, SEM, HR-TEM, DSC, and galvanostatic test show that the crystallite size (XS) of Li(Ni0.5Co0.2Mn0.3)O2 is greatly affected by the temperature in the range of 750 to 820 °C. Most of all, the crystallite size plays a unique role in the performance of the material. That is, the electrochemical characteristics of Li(Ni0.5Co0.2Mn0.3)O2, such as discharge capacity, rate performance, and thermal stability, are closely related to the crystallite size. Furthermore, the retention of discharge capacity is determined by that of crystallite size in Li(Ni0.5Co0.2Mn0.3)O2 after 100 cycles.

  11. Effects of Precipitant and pH on Coprecipitation of Nanosized Co-Cr-V Alloy Powders

    PubMed Central

    Chen, Xiaoyu; Li, Yongxia; Huang, Lan; Zou, Dan; Wu, Enxi; Liu, Yanjun; Xie, Yuanyan; Yao, Rui; Liao, Songyi; Wang, Guangrong

    2017-01-01

    Nanosized Co-Cr-V alloy powders were synthesized via coprecipitation method. Effects of precipitants ((NH4)2C2O4·H2O and Na2CO3) and pH were investigated by X-ray diffraction (XRD), Zeta potential analyzer, thermogravimetry-differential scanning calorimetry (TG-DSC), inductively coupled plasma-atomic emission spectrometry (ICP-AES) and scanning electron microscopy (SEM). Co-Cr-V alloy powders were consisted of major face-centered cubic Co (fcc Co) and minor hexagonal close-packed Co (hcp Co). Grain sizes of precursors and Co-Cr-V alloy powders were increased with pH value (7–10) within the ranges of 3~39 and 39~66 nm, respectively. Rod-like or granular Co-Cr-V alloy particles were assembled by interconnected nanograins. At pH = 7, Na2CO3 precipitant was found to be beneficial to maintain the desirable composition of Co-Cr-V powders. It was also found that lower pH favors the maintenance of pre-designed composition, while grain coarsens at higher pH. Effects of variation for precipitant and pH on the morphology and composition of Co-Cr-V alloy powder were discussed in detail and relevant mechanism was further proposed. PMID:28934147

  12. Strain-induced dimensionality crossover of precursor modulations in Ni2MnGa

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nie, Zhihua; Wang, Yandong; Shang, Shunli

    2015-01-01

    Precursor modulations often occur in functional materials like magnetic shape memory alloys, ferroelectrics, and superconductors. In this letter, we have revealed the underlying mechanism of the precursor modulations in ferromagnetic shape memory alloys Ni2MnGa by combining synchrotron-based x-ray diffraction experiments and first-principles phonon calculations. We discovered the precursor modulations along [011] direction can be eliminated with [001] uniaxial loading, while the precursor modulations or premartensite can be totally suppressed by hydrostatic pressure condition. The TA2 phonon anomaly is sensitive to stress induced lattice strain, and the entire TA2 branch is stabilized along the directions where precursor modulations are eliminated bymore » external stress. Our discovery bridges precursor modulations and phonon anomalies, and sheds light on the microscopic mechanism of the two-step superelasticity in precursor martensite.« less

  13. Growth of Nanosized Single Crystals for Efficient Perovskite Light-Emitting Diodes.

    PubMed

    Lee, Seungjin; Park, Jong Hyun; Nam, Yun Seok; Lee, Bo Ram; Zhao, Baodan; Di Nuzzo, Daniele; Jung, Eui Dae; Jeon, Hansol; Kim, Ju-Young; Jeong, Hu Young; Friend, Richard H; Song, Myoung Hoon

    2018-04-24

    Organic-inorganic hybrid perovskites are emerging as promising emitting materials due to their narrow full-width at half-maximum emissions, color tunability, and high photoluminescence quantum yields (PLQYs). However, the thermal generation of free charges at room temperature results in a low radiative recombination rate and an excitation-intensity-dependent PLQY, which is associated with the trap density. Here, we report perovskite films composed of uniform nanosized single crystals (average diameter = 31.7 nm) produced by introducing bulky amine ligands and performing the growth at a lower temperature. By effectively controlling the crystal growth, we maximized the radiative bimolecular recombination yield by reducing the trap density and spatially confining the charges. Finally, highly bright and efficient green emissive perovskite light-emitting diodes that do not suffer from electroluminescence blinking were achieved with a luminance of up to 55 400 cd m -2 , current efficiency of 55.2 cd A -1 , and external quantum efficiency of 12.1%.

  14. Ceramic fibers from Si-B-C polymer precursors

    NASA Technical Reports Server (NTRS)

    Riccitiello, S. R.; Hsu, M. S.; Chen, T. S.

    1993-01-01

    Non-oxide ceramics such as silicon carbide (SiC), silicon nitride (Si3N4), and silicon borides (SiB4, SiB6) have thermal stability, oxidation resistance, hardness, and varied electrical properties. All these materials can be prepared in a fiber form from a suitable polymer precursor. The above mentioned fibers, when tested over a temperature range from 25 to 1400 C, experience degradation at elevated temperatures. Past work in ceramic materials has shown that the strength of ceramics containing both carbides and borides is sustained at elevated temperatures, with minimum oxidation. The work presented here describes the formation of ceramic fibers containing both elements, boron and silicon, prepared via the polymer precursor route previously reported by the authors, and discusses the fiber mechanical properties that are retained over the temperature range studied.

  15. The artists' materials of Fernando Melani: A precursor of the Poor Art artistic movement in Italy

    NASA Astrophysics Data System (ADS)

    Carlesi, Serena; Bartolozzi, Giovanni; Cucci, Costanza; Marchiafava, Veronica; Picollo, Marcello

    2013-03-01

    A comprehensive understanding of both the chemical composition and physical behaviour of modern materials is an important consideration in devising correct conservation treatments for contemporary artworks. To this end, national and international research projects and networks have been established that deal mainly with the preservation, conservation, and understanding of materials used by contemporary artists. This paper focuses on the self-taught artist Fernando Melani (1907-1985), one of the precursors of the Poor Art artistic movement in Italy, and for the first time provides a scientific viewpoint on the artist's materials and works. The analyses, which mainly focus on the pigments/dyes found in his home-studio, were carried out primarily by using Fourier Transform Infrared Spectroscopy (FT-IR) and ultraviolet, visible, and near-infrared Fibre Optic Reflectance Spectroscopy (UV-Vis-NIR FORS). This paper emphasises the performance of FT-IR and FORS in the identification of contemporary artistic materials, since these two techniques have been found to produce highly complementary data. The use of both of these was required in order to obtain a comprehensive understanding of the composition of Melani's materials. Furthermore, one of his artworks, named by Melani himself with its inventory number N. Inv. 2625 (1981), was investigated in situ with the sole use of the FORS technique. The results showed that Melani used traditional inorganic pigments as well as modern organic dyes. Calcite and barite were used as fillers and extenders. Sulphur and abrasive powder were also found, thus confirming his use of a large variety of non-conventional artists' materials.

  16. Synthesis and characterization of mesoporous ceria/alumina nanocomposite materials via mixing of the corresponding ceria and alumina gel precursors.

    PubMed

    Khalil, Kamal M S

    2007-03-01

    Mesoporous ceria/alumina, CeO(2)/Al(2)O(3), composites containing 10, 20 and 30% (w/w) ceria were prepared by a novel gel mixing method. In the method, ceria gel (formed via hydrolysis of ammonium cerium(IV) nitrate by aqueous ammonium carbonate solution) and alumina gel (formed via controlled hydrolysis of aluminum tri-isopropoxide) were mixed together. The mixed gel was subjected to subsequent drying and calcination for 3 h at 400, 600, 800 and 1000 degrees C. The uncalcined (dried at 110 degrees C) and the calcined composites were investigated by different techniques including TGA, DSC, FTIR, XRD, SEM and nitrogen adsorption/desorption isotherms. Results indicated that composites calcined for 3 h at 800 degrees C mainly kept amorphous alumina structure and gamma-alumina formed only upon calcinations at 1000 degrees C. On the other hand, CeO(2) was found to crystallize in the common ceria, cerinite, phase and it kept this structure over the entire calcination range (400-1000 degrees C). Therefore, high surface areas, stable surface textures, and non-aggregated nano-sized ceria dispersions were obtained. A systematic texture change based on ceria ratio was observed, however in all cases mesoporous composite materials exposing thermally stable texture and structure were obtained. The presented method produces composite ceria/alumina materials that suit different applications in the field of catalysis and membranes technology, and throw some light on physicochemical factors that determine textural morphology and thermal stability of such important composite.

  17. A facile synthesis of α-MnO2 used as a supercapacitor electrode material: The influence of the Mn-based precursor solutions on the electrochemical performance

    NASA Astrophysics Data System (ADS)

    Li, Wenyao; Xu, Jiani; Pan, Yishuang; An, Lei; Xu, Kaibing; Wang, Guangjin; Yu, Zhishui; Yu, Li; Hu, Junqing

    2015-12-01

    Three types of α-MnO2 nanomaterials are synthesized in different Mn-based precursor solutions by using a facile electrochemical deposition at the same depositional condition. The relationships between the precursor solutions and corresponding MnO2 nanomaterials' morphology as well as the electrochemical performance have been studied. As an electrode, electrochemical measurements show that the MnO2 deposited in MnCl2 precursor solution (MnO2-P3) exhibits an enhanced specific capacitance (318.9 F g-1 at 2 mV s-1). Moreover, this electrode demonstrates a good rate capability with 44% retention, which is higher than the MnO2-P1 deposited with Mn(CH3COOH)2 solution and the MnO2-P2 deposited with Mn(NO3)2 precursor solution. Besides, the specific capacitance of the MnO2-P3 electrode nearly has 98.2% retention after 2000 cycles, showing good long-term cycle stability. These findings show that the MnO2-P3 is a promising electrode material for supercapacitors.

  18. Constrained Geometry Organotitanium Catalysts Supported on Nanosized Silica for Ethylene (co)Polymerization.

    PubMed

    Li, Kuo-Tseng; Wu, Ling-Huey

    2017-05-05

    Supported olefin polymerization catalysts can prevent reactor-fouling problems and produce uniform polymer particles. Constrained geometry complexes (CGCs) have less sterically hindered active sites than bis-cyclopentadienyl metallocene catalysts. In the literature, micrometer-sized silica particles were used for supporting CGC catalysts, which might have strong mass transfer limitations. This study aims to improve the activity of supported CGC catalysts by using nanometer-sized silica. Ti[(C₅Me₄)SiMe₂(N t Bu)]Cl₂, a "constrained-geometry" titanium catalyst, was supported on MAO-treated silicas (nano-sized and micro-sized) by an impregnation method. Ethylene homo-polymerization and co-polymerization with 1-octene were carried out in a temperature range of 80-120 °C using toluene as the solvent. Catalysts prepared and polymers produced were characterized. For both catalysts and for both reactions, the maximum activities occurred at 100 °C, which is significantly higher than that (60 °C) reported before for supported bis-cyclopentadienyl metallocene catalysts containing zirconium, and is lower than that (≥140 °C) used for unsupported Ti[(C₅Me₄)SiMe₂(N t Bu)]Me₂ catalyst. Activities of nano-sized catalyst were 2.6 and 1.6 times those of micro-sized catalyst for homopolymerization and copolymerization, respectively. The former produced polymers with higher crystallinity and melting point than the latter. In addition, copolymer produced with nanosized catalyst contained more 1-octene than that produced with microsized catalyst.

  19. Effect of fluoride toothpaste with nano-sized trimetaphosphate on enamel demineralization: An in vitro study.

    PubMed

    Danelon, Marcelle; Pessan, Juliano Pelim; Souza-Neto, Francisco Nunes; de Camargo, Emerson Rodrigues; Delbem, Alberto Carlos Botazzo

    2017-06-01

    This study evaluated the effect of toothpastes containing 1100ppm F associated or not with micrometric or nano-sized sodium trimetaphosphate (TMP) on enamel demineralization in vitro, using a pH cycling model. Bovine enamel blocks (4mm×4mm, n=96) were randomly allocated into eight groups (n=12), according to the test toothpastes: Placebo (without fluoride or TMP); 1100ppm F (1100F); 1100F plus micrometric TMP at concentrations of 1%, 3% or 6%; and 1100F plus nanosized TMP at 1%, 3% or 6%. Blocks were treated 2×/day with slurries of toothpastes and submitted to a pH cycling regimen for five days. Next, final surface hardness (SHf), integrated hardness loss (IHL), differential profile of integrated hardness loss (ΔIHL) and enamel fluoride (F) concentrations were determined. Data were analyzed by ANOVA and Student-Newman-Keuls' test (p<0.05). The use of 1100F/3%TMPnano led to SHf 30% higher (p<0.001) and IHL∼80% lower (p<0.001) when compared to 1100F. This toothpaste also resulted in ∼64% reduction of mineral loss (ΔIHL) when compared to 1100F. Moreover, the addition of nano-sized TMP promoted increases in enamel F uptake of 90%, 160% and 100%, respectively for the concentrations of 1%, 3% and 6%, when compared to 1100F (p<0.001). The addition of nano-sized TMP at 3% to a conventional toothpaste significantly decreased enamel demineralization when compared to its counterparts without TMP or supplemented with micrometric TMP. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Nanosizing of drugs: Effect on dissolution rate

    PubMed Central

    Dizaj, S. Maleki; Vazifehasl, Zh.; Salatin, S.; Adibkia, Kh.; Javadzadeh, Y.

    2015-01-01

    The solubility, bioavailability and dissolution rate of drugs are important parameters for achieving in vivo efficiency. The bioavailability of orally administered drugs depends on their ability to be absorbed via gastrointestinal tract. For drugs belonging to Class II of pharmaceutical classification, the absorption process is limited by drug dissolution rate in gastrointestinal media. Therefore, enhancement of the dissolution rate of these drugs will present improved bioavailability. So far several techniques such as physical and chemical modifications, changing in crystal habits, solid dispersion, complexation, solubilization and liquisolid method have been used to enhance the dissolution rate of poorly water soluble drugs. It seems that improvement of the solubility properties ofpoorly water soluble drugscan translate to an increase in their bioavailability. Nowadays nanotechnology offers various approaches in the area of dissolution enhancement of low aqueous soluble drugs. Nanosizing of drugs in the form of nanoparticles, nanocrystals or nanosuspensions not requiring expensive facilities and equipment or complicated processes may be applied as simple methods to increase the dissolution rate of poorly water soluble drugs. In this article, we attempted to review the effects of nanosizing on improving the dissolution rate of poorly aqueous soluble drugs. According to the reviewed literature, by reduction of drug particle size into nanometer size the total effective surface area is increased and thereby dissolution rate would be enhanced. Additionally, reduction of particle size leads to reduction of the diffusion layer thickness surrounding the drug particles resulting in the increment of the concentration gradient. Each of these process leads to improved bioavailability. PMID:26487886

  1. Spectral ellipsometry as a method for characterization of nanosized films with ferromagnetic layers

    NASA Astrophysics Data System (ADS)

    Hashim, H.; Singkh, S. P.; Panina, L. V.; Pudonin, F. A.; Sherstnev, I. A.; Podgornaya, S. V.; Shpetnyi, I. A.; Beklemisheva, A. V.

    2017-11-01

    Nanosized films with ferromagnetic layers are widely used in nanoelectronics, sensor systems and telecommunications. Their properties may strongly differ from those of bulk materials that is on account of interfaces, intermediate layers and diffusion. In the present work, spectral ellipsometry and magnetooptical methods are adapted for characterization of the optical parameters and magnetization processes in two- and three-layer Cr/NiFe, Al/NiFe and Cr(Al)/Ge/NiFe films onto a sitall substrate for various thicknesses of Cr and Al layers. At a layer thickness below 20 nm, the complex refractive coefficients depend pronouncedly on the thickness. In two-layer films, remagnetization changes weakly over a thickness of the top layer, but the coercive force in three-layer films increases by more than twice upon remagnetization, while increasing the top layer thickness from 4 to 20 nm.

  2. Strain-induced dimensionality crossover of precursor modulations in Ni{sub 2}MnGa

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nie, Zhihua, E-mail: zhihua-nie@yahoo.com, E-mail: ydwang@neu.edu.cn; Wang, Yandong, E-mail: zhihua-nie@yahoo.com, E-mail: ydwang@neu.edu.cn; Shang, Shunli

    2015-01-12

    Precursor modulations often occur in functional materials like magnetic shape memory alloys, ferroelectrics, and superconductors. In this letter, we have revealed the underlying mechanism of the precursor modulations in ferromagnetic shape memory alloys Ni{sub 2}MnGa by combining synchrotron-based x-ray diffraction experiments and first-principles phonon calculations. We discovered the precursor modulations along [011] direction can be eliminated with [001] uniaxial loading, while the precursor modulations or premartensite can be totally suppressed by hydrostatic pressure condition. The TA{sub 2} phonon anomaly is sensitive to stress induced lattice strain, and the entire TA{sub 2} branch is stabilized along the directions where precursor modulationsmore » are eliminated by external stress. Our discovery bridges precursor modulations and phonon anomalies, and sheds light on the microscopic mechanism of the two-step superelasticity in precursor martensite.« less

  3. Nanosized IrO2 electrocatalysts for oxygen evolution reaction in an SPE electrolyzer

    NASA Astrophysics Data System (ADS)

    Cruz, J. C.; Baglio, V.; Siracusano, S.; Ornelas, R.; Ortiz-Frade, L.; Arriaga, L. G.; Antonucci, V.; Aricò, A. S.

    2011-04-01

    Nanosized IrO2 electrocatalysts ( d 7-9 nm) with specific surface area up to 100 m2 g-1 were synthesized and characterized for the oxygen evolution reaction in a solid polymer electrolyte (SPE) electrolyzer. The catalysts were prepared by a colloidal method in aqueous solution and a subsequent thermal treatment. An iridium hydroxide hydrate precursor was obtained at 100 °C, which was, successively, calcined at different temperatures from 200 to 500 °C. The physico-chemical characterization was carried out by X-ray diffraction (XRD), thermogravimetry-differential scanning calorimetry (TG-DSC) and transmission electron microscopy (TEM). IrO2 catalysts were sprayed onto a Nafion 115 membrane up to a loading of 3 mg cm-2. A Pt catalyst was used at the cathode compartment with a loading of 0.6 mg cm-2. The electrochemical activity for water electrolysis of the membrane-electrode assemblies (MEAs) was investigated in a single cell SPE electrolyzer by steady-state polarization curves, impedance spectroscopy and chrono-amperometric measurements. A maximum current density of 1.3 A cm-2 was obtained at 1.8 V and 80 °C for the IrO2 catalyst calcined at 400 °C for 1 h. A stable performance was recorded in single cell for this anode catalyst at 80 °C. The suitable catalytic activity and stability of the most performing catalyst were interpreted in terms of proper combination between nanostructure and suitable morphology.

  4. Targeted Therapy for Acute Autoimmune Myocarditis with Nano-Sized Liposomal FK506 in Rats.

    PubMed

    Okuda, Keiji; Fu, Hai Ying; Matsuzaki, Takashi; Araki, Ryo; Tsuchida, Shota; Thanikachalam, Punniyakoti V; Fukuta, Tatsuya; Asai, Tomohiro; Yamato, Masaki; Sanada, Shoji; Asanuma, Hiroshi; Asano, Yoshihiro; Asakura, Masanori; Hanawa, Haruo; Hao, Hiroyuki; Oku, Naoto; Takashima, Seiji; Kitakaze, Masafumi; Sakata, Yasushi; Minamino, Tetsuo

    2016-01-01

    Immunosuppressive agents are used for the treatment of immune-mediated myocarditis; however, the need to develop a more effective therapeutic approach remains. Nano-sized liposomes may accumulate in and selectively deliver drugs to an inflammatory lesion with enhanced vascular permeability. The aims of this study were to investigate the distribution of liposomal FK506, an immunosuppressive drug encapsulated within liposomes, and the drug's effects on cardiac function in a rat experimental autoimmune myocarditis (EAM) model. We prepared polyethylene glycol-modified liposomal FK506 (mean diameter: 109.5 ± 4.4 nm). We induced EAM by immunization with porcine myosin and assessed the tissue distribution of the nano-sized beads and liposomal FK506 in this model. After liposomal or free FK506 was administered on days 14 and 17 after immunization, the cytokine expression in the rat hearts along with the histological findings and hemodynamic parameters were determined on day 21. Ex vivo fluorescent imaging revealed that intravenously administered fluorescent-labeled nano-sized beads had accumulated in myocarditic but not normal hearts on day 14 after immunization and thereafter. Compared to the administration of free FK506, FK506 levels were increased in both the plasma and hearts of EAM rats when liposomal FK506 was administered. The administration of liposomal FK506 markedly suppressed the expression of cytokines, such as interferon-γ and tumor necrosis factor-α, and reduced inflammation and fibrosis in the myocardium on day 21 compared to free FK506. The administration of liposomal FK506 also markedly ameliorated cardiac dysfunction on day 21 compared to free FK506. Nano-sized liposomes may be a promising drug delivery system for targeting myocarditic hearts with cardioprotective agents.

  5. Ground-based simulation of the Earth's upper atmosphere oxygen impact on polymer composites with nanosized fillers

    NASA Astrophysics Data System (ADS)

    Novikov, Lev; Chernik, Vladimir; Voronina, Ekaterina; Chechenin, Nikolay; Samokhina, Maria S.; Bondarenko, Gennady G.; Gaidar, Anna I.; Vorobyeva, Ekaterina A.; Petrov, Dmitrii V.; Chirskaya, Natalia P.

    The improvement of durability of polymer composites to the space environment impact is a very important task because these materials are considered currently as very promising type of materials for aerospace engineering. By embedding various nanosized fillers into a polymer matrix it is possible to obtain composites with required mechanical, thermal, electrical and optic properties. However, while developing such materials for operation in low Earth orbits (LEO), it is necessary to study thoroughly their durability to the impact of atomic oxygen (AO) of the Earth’s upper atmosphere, because AO is the main factor that causes erosion and damage of spacecraft surface materials in LEO. Ground-based simulation of AO impact on polymer composites was performed on a magnetoplasmadynamic accelerator developed at Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University. Polymer composite samples which were prepared as films of 30-50 mum thickness with different amount (3-20 wt%) of various inorganic and organic nanofillers including nanoparticles of metal oxides and carbides as well as polyethoxysiloxanes and carbon nanotubes (CNTs), were exposed to hyperthermal AO flow, and mass losses of samples were estimated. Changes in the structure of composite surface and in material optical properties were studied. The experiments demonstrated that embedding nanosized fillers into a polymer matrix can significantly reduced mass losses, and the good dispersion of fillers improves AO durability in comparison with initial polymers [1]. The computer simulation within the developed 2D Monte-Carlo model demonstrated a good agreement with the experimental data [2]. Special attention was given to the study of AO impact on aligned multiwalled CNTs and CNT-based composites [3]. Some results of computer simulation of hyperthermal oxygen atom interaction with CNT and graphene as well as with polymers are presented to discuss elementary processes which occur in nanostructures

  6. Dispersion of nanosized ceramic powders in aqueous suspensions

    NASA Astrophysics Data System (ADS)

    Chera, L.; Palcevskis, E.; Berzins, M.; Lipe, A.; Jansone, I.

    2007-12-01

    Seven commercially available dispersants have been applied to produce high concentrated aqueous suspensions of the nanosized alumina and partially stabilized zirconia powders processed by the plasma technique. Simultaneously, the electrokinetic behaviour of powders has been investigated in diluted suspensions by microelectrophoresis method. Zeta potential measurements are used to estimate the influence of selected dispersants on the electrokinetic properties of the powder surface. On the basis of obtained data the correlation between the surface electrokinetic properties in dilute suspensions and reached maximal suspension concentration is discussed.

  7. Aqueous silicates in biological sol-gel applications: new perspectives for old precursors.

    PubMed

    Coradin, Thibaud; Livage, Jacques

    2007-09-01

    Identification of silica sol-gel chemistry with silicon alkoxide hydrolysis and condensation processes is common in modern materials science. However, aqueous silicates exhibit several features indicating that they may be more suitable precursors for specific fields of research and applications related to biology and medicine. In this Account, we illustrate the potentialities of such aqueous precursors for biomimetic studies, bio-hybrid material design, and bioencapsulation routes. We emphasize that the natural relevance, the biocompatibility, and the low ecological impact of silicate chemistry may balance its lack of diversity, flexibility, and processability.

  8. The artists' materials of Fernando Melani: a precursor of the Poor Art artistic movement in Italy.

    PubMed

    Carlesi, Serena; Bartolozzi, Giovanni; Cucci, Costanza; Marchiafava, Veronica; Picollo, Marcello

    2013-03-01

    A comprehensive understanding of both the chemical composition and physical behaviour of modern materials is an important consideration in devising correct conservation treatments for contemporary artworks. To this end, national and international research projects and networks have been established that deal mainly with the preservation, conservation, and understanding of materials used by contemporary artists. This paper focuses on the self-taught artist Fernando Melani (1907-1985), one of the precursors of the Poor Art artistic movement in Italy, and for the first time provides a scientific viewpoint on the artist's materials and works. The analyses, which mainly focus on the pigments/dyes found in his home-studio, were carried out primarily by using Fourier Transform Infrared Spectroscopy (FT-IR) and ultraviolet, visible, and near-infrared Fibre Optic Reflectance Spectroscopy (UV-Vis-NIR FORS). This paper emphasises the performance of FT-IR and FORS in the identification of contemporary artistic materials, since these two techniques have been found to produce highly complementary data. The use of both of these was required in order to obtain a comprehensive understanding of the composition of Melani's materials. Furthermore, one of his artworks, named by Melani himself with its inventory number N. Inv. 2625 (1981), was investigated in situ with the sole use of the FORS technique. The results showed that Melani used traditional inorganic pigments as well as modern organic dyes. Calcite and barite were used as fillers and extenders. Sulphur and abrasive powder were also found, thus confirming his use of a large variety of non-conventional artists' materials. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. The nature of nano-sized precipitates in ferritic/martensitic steel P92 produced by thermomechanical treatment

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shen, Yinzhong, E-mail: shenyz@sjtu.edu.cn

    Thermomechanical treatment (TMT) can effectively improve the mechanical properties of high-Cr ferritic/martensitic (F/M) steels, which has been mainly attributed to a dense dispersion of nano-sized precipitates. Precipitate phases in high-Cr F/M steels produced by TMT require further investigations. Precipitates in commercial F/M steel P92 produced by a TMT process, warm-rolled at 650 °C plus tempered at 650 °C for 1 h, were investigated by transmission electron microscopy. Nano-sized precipitates with a high number density in the steel after the TMT were found to be Cr-rich M{sub 2}(C,N) carbonitride, rather than MX or M{sub 23}C{sub 6} phase. The M{sub 2}(C,N) carbonitridemore » has a hexagonal lattice with the lattice parameters about a/c = 0.299/0.463 nm. These M{sub 2}(C,N) carbonitrides with a typical composition of (Cr{sub 0.85}V{sub 0.06}Fe{sub 0.06}Mo{sub 0.03}){sub 2}(C,N) have an average diameter smaller than 30 nm, and mainly distribute on dislocations and at the boundaries of equiaxed ferrite grains in the TMT steel. The TMT process inhibits the precipitation of M{sub 23}C{sub 6} and M{sub 5}C{sub 2} phases. Enhanced creep properties of the P92 steel after the TMT, as reported previously, were considered to be mainly attributed to plenty of nano-sized Cr-rich M{sub 2}(C,N) carbonitrides produced by the TMT rather than to MX and M{sub 23}C{sub 6} precipitates. - Graphical abstract: TEM micrographs of precipitates on extraction carbon replicas prepared from ferritic/martensitic (F/M) steel P92. (a) After conventional heat treatment, normalized at 1050 °C for 30 min plus tempered at 765 °C for 1 h. (b) After a thermomechanical treatment (TMT), warm-rolled at 650 °C plus tempered at 650 °C for 1 h. Nano-sized precipitates with a high number density in the steel produced by the TMT were found to be Cr-rich M{sub 2}(C,N) carbonitride, rather than MX or M{sub 23}C{sub 6} phase. The TMT process inhibits the precipitation of M{sub 23}C{sub 6} and M

  10. Nano-sized Mo- and Nb-doped TiO2 as anode materials for high energy and high power hybrid Li-ion capacitors.

    PubMed

    Bauer, Dustin; Roberts, Alexander J; Matsumi, Noriyoshi; Darr, Jawwad A

    2017-05-12

    Nano-sized Mo-doped titania (Mo 0.1 Ti 0.9 O 2 ) and Nb-doped titania (Nb 0.25 Ti 0.75 O 2 ) were directly synthesized via a continuous hydrothermal flow synthesis process. Materials characterization was conducted using physical techniques such as transmission electron microscopy, powder x-ray diffraction, x-ray photoelectron spectroscopy, Brunauer-Emmett-Teller specific surface area measurements and energy dispersive x-ray spectroscopy. Hybrid Li-ion supercapacitors were made with either a Mo-doped or Nb-doped TiO 2 negative electrode material and an activated carbon (AC) positive electrode. Cells were evaluated using electrochemical testing (cyclic voltammetry, constant charge discharge cycling). The hybrid Li-ion capacitors showed good energy densities at moderate power densities. When cycled in the potential window 0.5-3.0 V, the Mo 0.1 Ti 0.9 O 2 /AC hybrid supercapacitor showed the highest energy densities of 51 Wh kg -1 at a power of 180 W kg -1 with energy densities rapidly declining with increasing applied specific current. In comparison, the Nb 0.25 Ti 0.75 O 2 /AC hybrid supercapacitor maintained its energy density of 45 Wh kg -1 at 180 W kg -1 better, showing 36 Wh g -1 at 3200 W kg -1 , which is a very promising mix of high energy and power densities. Reducing the voltage window to the range 1.0-3.0 V led to an increase in power density, with the Mo 0.1 Ti 0.9 O 2 /AC hybrid supercapacitor giving energy densities of 12 Wh kg -1 and 2.5 Wh kg -1 at power densities of 6700 W kg -1 and 14 000 W kg -1 , respectively.

  11. Nano-sized Mo- and Nb-doped TiO2 as anode materials for high energy and high power hybrid Li-ion capacitors

    NASA Astrophysics Data System (ADS)

    Bauer, Dustin; Roberts, Alexander J.; Matsumi, Noriyoshi; Darr, Jawwad A.

    2017-05-01

    Nano-sized Mo-doped titania (Mo0.1Ti0.9O2) and Nb-doped titania (Nb0.25Ti0.75O2) were directly synthesized via a continuous hydrothermal flow synthesis process. Materials characterization was conducted using physical techniques such as transmission electron microscopy, powder x-ray diffraction, x-ray photoelectron spectroscopy, Brunauer-Emmett-Teller specific surface area measurements and energy dispersive x-ray spectroscopy. Hybrid Li-ion supercapacitors were made with either a Mo-doped or Nb-doped TiO2 negative electrode material and an activated carbon (AC) positive electrode. Cells were evaluated using electrochemical testing (cyclic voltammetry, constant charge discharge cycling). The hybrid Li-ion capacitors showed good energy densities at moderate power densities. When cycled in the potential window 0.5-3.0 V, the Mo0.1Ti0.9O2/AC hybrid supercapacitor showed the highest energy densities of 51 Wh kg-1 at a power of 180 W kg-1 with energy densities rapidly declining with increasing applied specific current. In comparison, the Nb0.25Ti0.75O2/AC hybrid supercapacitor maintained its energy density of 45 Wh kg-1 at 180 W kg-1 better, showing 36 Wh g-1 at 3200 W kg-1, which is a very promising mix of high energy and power densities. Reducing the voltage window to the range 1.0-3.0 V led to an increase in power density, with the Mo0.1Ti0.9O2/AC hybrid supercapacitor giving energy densities of 12 Wh kg-1 and 2.5 Wh kg-1 at power densities of 6700 W kg-1 and 14 000 W kg-1, respectively.

  12. Silicone Resin Applications for Ceramic Precursors and Composites

    PubMed Central

    Narisawa, Masaki

    2010-01-01

    This article reviews the applications of silicone resins as ceramic precursors. The historical background of silicone synthesis chemistry is introduced to explain the production costs and supply availability of various silicones. Thermal degradation processes of silicones are classified in terms of the main chain structure and cyclic oligomer expulsion process, which determine the resulting ceramic yield and the chemical composition. The high temperature decomposition of Si-O-C beyond 1,400 °C in an inert atmosphere and formation of a protective silica layer on material surfaces beyond 1,200 °C in an oxidative atmosphere are discussed from the viewpoints of the wide chemical composition of the Si-O-C materials. Applications of the resins for binding agents, as starting materials for porous ceramics, matrix sources with impregnation, fiber spinning and ceramic adhesions are introduced. The recent development of the process of filler or cross-linking agent additions to resin compounds is also introduced. Such resin compounds are useful for obtaining thick coatings, MEMS parts and bulk ceramics, which are difficult to obtain by pyrolysis of simple organometallic precursors without additives.

  13. Mechanical Properties and Microstructure of Biomorphic Silicon Carbide Ceramics Fabricated from Wood Precursors

    NASA Technical Reports Server (NTRS)

    Singh, Mrityunjay; Salem, J. A.; Gray, Hugh R. (Technical Monitor)

    2002-01-01

    Silicon carbide based, environment friendly, biomorphic ceramics have been fabricated by the pyrolysis and infiltration of natural wood (maple and mahogany) precursors. This technology provides an eco-friendly route to advanced ceramic materials. These biomorphic silicon carbide ceramics have tailorable properties and behave like silicon carbide based materials manufactured by conventional approaches. The elastic moduli and fracture toughness of biomorphic ceramics strongly depend on the properties of starting wood preforms and the degree of molten silicon infiltration. Mechanical properties of silicon carbide ceramics fabricated from maple wood precursors indicate the flexural strengths of 3441+/-58 MPa at room temperature and 230136 MPa at 1350C. Room temperature fracture toughness of the maple based material is 2.6 +/- 0.2 MPa(square root of)m while the mahogany precursor derived ceramics show a fracture toughness of 2.0 +/- 0.2 Mpa(square root of)m. The fracture toughness and the strength increase as the density of final material increases. Fractographic characterization indicates the failure origins to be pores and chipped pockets of silicon.

  14. NANOSIZE TITANIA STIMULATES REACTIVE OXYGEN SPECIES IN BRAIN MICROGLIA AND DAMAGES NEURONS.

    EPA Science Inventory

    Research that addresses the environmental impact and biological consequences of widely distributed, commonly used nanoparticles is needed. Nanosize titanium dioxide (i.e., titania, TiO2) is used in air and water remediation and in numerous products designed for direct human us...

  15. Nano-sized manganese oxides as biomimetic catalysts for water oxidation in artificial photosynthesis: a review

    PubMed Central

    Najafpour, Mohammad Mahdi; Rahimi, Fahimeh; Aro, Eva-Mari; Lee, Choon-Hwan; Allakhverdiev, Suleyman I.

    2012-01-01

    There has been a tremendous surge in research on the synthesis of various metal compounds aimed at simulating the water-oxidizing complex (WOC) of photosystem II (PSII). This is crucial because the water oxidation half reaction is overwhelmingly rate-limiting and needs high over-voltage (approx. 1 V), which results in low conversion efficiencies when working at current densities required for hydrogen production via water splitting. Particular attention has been given to the manganese compounds not only because manganese has been used by nature to oxidize water but also because manganese is cheap and environmentally friendly. The manganese–calcium cluster in PSII has a dimension of about approximately 0.5 nm. Thus, nano-sized manganese compounds might be good structural and functional models for the cluster. As in the nanometre-size of the synthetic models, most of the active sites are at the surface, these compounds could be more efficient catalysts than micrometre (or bigger) particles. In this paper, we focus on nano-sized manganese oxides as functional and structural models of the WOC of PSII for hydrogen production via water splitting and review nano-sized manganese oxides used in water oxidation by some research groups. PMID:22809849

  16. Morphology and phase identification of micron to nanosized manganese oxide (MnO) with variations in sintering time

    NASA Astrophysics Data System (ADS)

    Sasongko, Muhammad Ilman Nur; Puspitasari, Poppy; Yazirin, Cepi; Tsamroh, Dewi Izzatus; Risdanareni, Puput

    2017-09-01

    Manganese oxide (MnO) occurs in many rock types and may take the form of minerals. MnO has its drawbacks, namely highly reactive oxidizing species classified as dangerous and explosive at temperatures above 55 °C. Despite this,MnO has excellent magnetic, electrochemical, and conductivity properties, which should be reduced to nano-size to maximize their use and improve the properties of MnO. Phase and morphology characterization of powder this research aims to reduce the grain size of the MnO from micro to nano using the sol-gel method with various sintering times. Sol-gel is a simple synthesis method that has been proven capable of synthesizing a wide variety of micro-sized oxide materials into nano. Sintering time is a technique performed in the synthesis process to dry the material to a temperature above the normal temperature. The temperature used for sintering starting from 600 °C to 1000 °C. Characterizations were done using XRD, SEM, EDX, and FTIR machines. The sintering processes in this study used a temperature of 600 °C with different sintering periods of 30, 60 and 90 minutes. The XRD characterization with a 30-minute sintering time resulted in the smallest MnO in the form crystalline powder of 47.3 nm. The highest intensity (degree of crystallinity) found in MnO sintered for 90 minutes. The results of the morphological characterization of SEM showed a morphological change in MnO from micro-sized triangular to nano-sized spherical shape. The EDX characterization results indicated that the 30-minute sintering caused the lowest change in Mn and the highest change in O. The results of FTIR characterization showed a shift in C-H and Mn-O followed by an increase in the group of N-H, C=O and Mn-O.

  17. Aroma Precursors in Grapes and Wine: Flavor Release during Wine Production and Consumption.

    PubMed

    Parker, Mango; Capone, Dimitra L; Francis, I Leigh; Herderich, Markus J

    2018-03-14

    Pioneering investigations into precursors of fruity and floral flavors established the importance of terpenoid and C 13 -norisoprenoid glycosides to the flavor of aromatic wines. Nowadays flavor precursors in grapes and wine are known to be structurally diverse, encompassing glycosides, amino acid conjugates, odorless volatiles, hydroxycinnamic acids, and many others. Flavor precursors mainly originate in the grape berry but also from oak or other materials involved in winemaking. Flavors are released from precursors during crushing and subsequent production steps by enzymatic and nonenzymatic transformations, via microbial glycosidases, esterases, C-S lyases, and decarboxylases, and through acid-catalyzed hydrolysis and chemical rearrangements. Flavors can also be liberated from glycosides and amino acid conjugates by oral microbiota. Hence, it is increasingly likely that flavor precursors contribute to retronasal aroma formation through in-mouth release during consumption, prompting a shift in focus from identifying aroma precursors in grapes to understanding aroma precursors present in bottled wine.

  18. Cd–cysteine precursor nanowire templated microwave-assisted transformation route to CdS nanotubes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liu, Xiao-Lin, E-mail: liu_x_l@sina.cn; Zhu, Ying-Jie; Zhang, Qian

    2012-12-15

    Graphical abstract: Cadmium sulfide polycrystalline nanotubes have been successfully synthesized by microwave-assisted transformation method using Cd–cysteine precursor nanowires as the source material and template in ethylene glycol at 160 °C or ethanol at 60 °C. Display Omitted Highlights: ► Cd–cysteine precursor nanowires were successfully synthesized in alkaline solution. ► CdS nanotubes were prepared by templated microwave-assisted transformation method. ► CdS nanotubes can well duplicate the size and morphology of precursor nanowires. ► This method has the advantages of the simplicity and low cost. -- Abstract: We report the Cd–cysteine precursor nanowire templated microwave-assisted transformation route to CdS nanotubes. In thismore » method, the Cd–cysteine precursor nanowires are synthesized using CdCl{sub 2}·2.5H{sub 2}O, L-cysteine and ethanolamine in water at room temperature. The Cd–cysteine precursor nanowires are used as the source material and template for the subsequent preparation of CdS nanotubes by a microwave-assisted transformation method using ethylene glycol or ethanol as the solvent. This method has the advantages of the simplicity and low cost, and may be extended to the synthesis of nanotubes of other compounds. The products are characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM).« less

  19. High-density amorphous ice: nucleation of nanosized low-density amorphous ice

    NASA Astrophysics Data System (ADS)

    Tonauer, Christina M.; Seidl-Nigsch, Markus; Loerting, Thomas

    2018-01-01

    The pressure dependence of the crystallization temperature of different forms of expanded high-density amorphous ice (eHDA) was scrutinized. Crystallization at pressures 0.05-0.30 GPa was followed using volumetry and powder x-ray diffraction. eHDA samples were prepared via isothermal decompression of very high-density amorphous ice at 140 K to different end pressures between 0.07-0.30 GPa (eHDA0.07-0.3). At 0.05-0.17 GPa the crystallization line T x (p) of all eHDA variants is the same. At pressures  >0.17 GPa, all eHDA samples decompressed to pressures  <0.20 GPa exhibit significantly lower T x values than eHDA0.2 and eHDA0.3. We rationalize our findings with the presence of nanoscaled low-density amorphous ice (LDA) seeds that nucleate in eHDA when it is decompressed to pressures  <0.20 GPa at 140 K. Below ~0.17 GPa, these nanosized LDA domains are latent within the HDA matrix, exhibiting no effect on T x of eHDA<0.2. Upon heating at pressures  ⩾0.17 GPa, these nanosized LDA nuclei transform to ice IX nuclei. They are favored sites for crystallization and, hence, lower T x . By comparing crystallization experiments of bulk LDA with the ones involving nanosized LDA we are able to estimate the Laplace pressure and radius of ~0.3-0.8 nm for the nanodomains of LDA. The nucleation of LDA in eHDA revealed here is evidence for the first-order-like nature of the HDA  →  LDA transition, supporting water’s liquid-liquid transition scenarios.

  20. High-performance oxygen reduction catalysts in both alkaline and acidic fuel cells based on pre-treating carbon material and iron precursor

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Song, Ping; Barkholtz, Heather M.; Wang, Ying

    We demonstrate a new and simple method for pre-treating the carbon material and iron precursor to prepare oxygen reduction reaction (ORR) catalysts, which can produce super-high performance and stability in alkaline solution, with high performance in acid solution. This strategy using cheap materials is simply controllable. Moreover, it has achieved smaller uniform nanoparticles to exhibit high stability, and the synergetic effect of Fe and N offered much higher performance in ORR than commercial Pt/C, with high maximum power density in alkaline and acid fuel cell test. So it can make this kind of catalysts be the most promising alternatives ofmore » Pt-based catalysts with best performance/price.« less

  1. Nondestructive Examination (NDE) Detection and Characterization of Degradation Precursors, Technical Progress Report for FY 2012

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ramuhalli, P.; Meyer, R.M.; Fricke, J.M.

    2012-09-01

    The overall objective of this project was to investigate the effectiveness of nondestructive examination (NDE) technology in detecting material degradation precursors by initiating and growing cracks in selected materials and using NDE methods to measure crack precursors prior to the onset of cracking. Nuclear reactor components are subject to stresses over time that are not precisely known and that make the life expectancy of components difficult to determine. To prevent future issues with the operation of these plants because of unforeseen failure of components, NDE technology is needed that can be used to identify and quantify precursors to macroscopic degradationmore » of materials. Some of the NDE methods being researched as possible solutions to the precursor detection problem are magnetic Barkhausen noise, nonlinear ultrasonics, acoustic emission, eddy current measurements, and guided wave technology. In FY12, the objective was to complete preliminary assessment of advanced NDE techniques for sensitivity to degradation precursors, using prototypical degradation mechanisms in laboratory-scale measurements. This present document reports on the deliverable that meets the following milestone: M3LW-12OR0402143 – Report detailing an initial demonstration on samples from the crack-initiation tests will be provided (demonstrating acceleration of the work).« less

  2. Characterization of the Phase Composition of Nanosized Lithium Titanates Synthesized by Inductive Thermal Plasma

    NASA Astrophysics Data System (ADS)

    Quesnel, François; Soucy, Gervais; Veilleux, Jocelyn; Hovington, Pierre; Zhu, Wen; Zaghib, Karim

    The properties of lithium titanates anodes in Li-ion batteries are highly dependent on their secondary constituents. While their main phase is usually constituted of Li4Ti5O12, significant quantity of lithium titanates compounds of various stoichiometry are often present, due to either the processing, usage or aging of the material. These may go underreported, as many of these spectrums overlap or display low signal in X-ray diffraction (XRD). Samples of nanosized lithium titanates synthetized by inductive plasma were characterized by XRD and scanning electron microscopy (SEM), as they provide a regular yet typical crystallite size and shape including multiple phases. A Rietveld refinement was developed to extract the composition of these samples. Mass balance through further annealing and differential scanning calorimetry (DSC) enthalpy measurements from phase transformations were also used as identification and validation techniques.

  3. Precursors of Halobenzoquinones and Their Removal During Drinking Water Treatment Processes.

    PubMed

    Wang, Wei; Qian, Yichao; Jmaiff, Lindsay K; Krasner, Stuart W; Hrudey, Steve E; Li, Xing-Fang

    2015-08-18

    Halobenzoquinones (HBQs) widely occur in drinking water treatment plant (DWTP) effluents; however, HBQ precursors and their removal by treatments remain unclear. Thus, we have investigated HBQ precursors in plant influents and their removal by each treatment before chlorination in nine DWTPs. The levels of HBQ precursors were determined using formation potential (FP) tests for 2,6-dichloro-1,4-benzoquinone (DCBQ), 2,3,6-trichloro-1,4-benzoquinone (TCBQ), 2,6-dichloro-3-methyl-1,4-benzoquinone (DCMBQ), and 2,6-dibromo-1,4-benzoquinone (DBBQ). HBQ precursors were present in all plant influents. DCBQ precursors were the most abundant (DCBQ FP up to 205 ng/L). Coagulation removed dissolved organic carbon (DOC) (up to 56%) and HBQ precursors (up to 39% for DCBQ). The level of removal of DOC was significantly greater than the level of removal of HBQ FP, suggesting that organic matter removed by coagulation had a high proportion of non-HBQ-precursor material. Granular activated carbon (GAC) decreased the level of HBQ FPs by 10-20%, where DOC removal was only 0.2-4.7%, suggesting that the GAC was not in the adsorption mode and biodegradation of HBQ precursors may have been occurring. Ozonation destroyed/transformed HBQ FPs by 10-30%, whereas anthracite/sand filtration and UV irradiation appeared to have no impact. The results demonstrated that the combined treatments did not substantially reduce HBQ precursor levels in water.

  4. TRANSPORT AND DEPOSITION OF NANO-SIZE PARTICLES IN THE UPPER HUMAN RESPIRATORY AIRWAYS

    EPA Science Inventory

    TRANSPORT AND DEPOSITION OF NANO-SIZE PARTICLES IN THE UPPER HUMAN RESPIRATORY AIRWAYS. Zhe Zhang*, Huawei Shi, Clement Kleinstreuer, Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695-7910; Chong S. Kim, National Health and En...

  5. Synthesis and characterization of scandia ceria stabilized zirconia powders prepared by polymeric precursor method for integration into anode-supported solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Tu, Hengyong; Liu, Xin; Yu, Qingchun

    2011-03-01

    Scandia ceria stabilized zirconia (10Sc1CeSZ) powders are synthesized by polymeric precursor method for use as the electrolyte of anode-supported solid oxide fuel cell (SOFC). The synthesized powders are characterized in terms of crystalline structure, particle shape and size distribution by X-ray diffraction (XRD), transmission electron microscopy (TEM) and photon correlation spectroscopy (PCS). 10Sc1CeSZ electrolyte films are deposited on green anode substrate by screen-printing method. Effects of 10Sc1CeSZ powder characteristics on sintered films are investigated regarding the integration process for application as the electrolytes in anode-supported SOFCs. It is found that the 10Sc1CeSZ films made from nano-sized powders with average size of 655 nm are very porous with many open pores. In comparison, the 10Sc1CeSZ films made from micron-sized powders with average size of 2.5 μm, which are obtained by calcination of nano-sized powders at higher temperatures, are much denser with a few closed pinholes. The cell performances are 911 mW cm-2 at the current density of 1.25 A cm-2 and 800 °C by application of Ce0.8Gd0.2O2 (CGO) barrier layer and La0.6Sr0.4CoO3 (LSC) cathode.

  6. Nano-sized polystyrene affects feeding, behavior and physiology of brine shrimp Artemia franciscana larvae.

    PubMed

    Bergami, Elisa; Bocci, Elena; Vannuccini, Maria Luisa; Monopoli, Marco; Salvati, Anna; Dawson, Kenneth A; Corsi, Ilaria

    2016-01-01

    Nano-sized polymers as polystyrene (PS) constitute one of the main challenges for marine ecosystems, since they can distribute along the whole water column affecting planktonic species and consequently disrupting the energy flow of marine ecosystems. Nowadays very little knowledge is available on the impact of nano-sized plastics on marine organisms. Therefore, the present study aims to evaluate the effects of 40nm anionic carboxylated (PS-COOH) and 50nm cationic amino (PS-NH2) polystyrene nanoparticles (PS NPs) on brine shrimp Artemia franciscana larvae. No signs of mortality were observed at 48h of exposure for both PS NPs at naplius stage but several sub-lethal effects were evident. PS-COOH (5-100μg/ml) resulted massively sequestered inside the gut lumen of larvae (48h) probably limiting food intake. Some of them were lately excreted as fecal pellets but not a full release was observed. Likewise, PS-NH2 (5-100µg/ml) accumulated in larvae (48h) but also adsorbed at the surface of sensorial antennules and appendages probably hampering larvae motility. In addition, larvae exposed to PS-NH2 undergo multiple molting events during 48h of exposure compared to controls. The activation of a defense mechanism based on a physiological process able to release toxic cationic NPs (PS-NH2) from the body can be hypothesized. The general observed accumulation of PS NPs within the gut during the 48h of exposure indicates a continuous bioavailability of nano-sized PS for planktonic species as well as a potential transfer along the trophic web. Therefore, nano-sized PS might be able to impair food uptake (feeding), behavior (motility) and physiology (multiple molting) of brine shrimp larvae with consequences not only at organism and population level but on the overall ecosystem based on the key role of zooplankton on marine food webs. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. InAs Colloidal Quantum Dots Synthesis via Aminopnictogen Precursor Chemistry.

    PubMed

    Grigel, Valeriia; Dupont, Dorian; De Nolf, Kim; Hens, Zeger; Tessier, Mickael D

    2016-10-05

    Despite their various potential applications, InAs colloidal quantum dots have attracted considerably less attention than more classical II-VI materials because of their complex syntheses that require hazardous precursors. Recently, amino-phosphine has been introduced as a cheap, easy-to-use and efficient phosphorus precursor to synthesize InP quantum dots. Here, we use aminopnictogen precursors to implement a similar approach for synthesizing InAs quantum dots. We develop a two-step method based on the combination of aminoarsine as the arsenic precursor and aminophosphine as the reducing agent. This results in state-of-the-art InAs quantum dots with respect to the size dispersion and band-gap range. Moreover, we present shell coating procedures that lead to the formation of InAs/ZnS(e) core/shell quantum dots that emit in the infrared region. This innovative synthesis approach can greatly facilitate the research on InAs quantum dots and may lead to synthesis protocols for a wide range of III-V quantum dots.

  8. A precursor system analysis of automated construction, maintenance, and operational requirements : resource materials

    DOT National Transportation Integrated Search

    1995-03-01

    This report documents work performed by the University of California at Davis in collaboration with the California Department of Transportation (Caltrans) in relationship to a Precursor System Analysis dealing with a study of automated construction, ...

  9. Heterometallic molecular precursors for a lithium-iron oxide material: synthesis, solid state structure, solution and gas-phase behaviour, and thermal decomposition.

    PubMed

    Han, Haixiang; Wei, Zheng; Barry, Matthew C; Filatov, Alexander S; Dikarev, Evgeny V

    2017-05-02

    Three heterometallic single-source precursors with a Li : Fe = 1 : 1 ratio for a LiFeO 2 oxide material are reported. Heterometallic compounds LiFeL 3 (L = tbaoac (1), ptac (2), and acac(3)) have been obtained on a large scale, in nearly quantitative yields by one-step reactions that employ readily available reagents. The heterometallic precursor LiFe(acac) 3 (3) with small, symmetric substituents on the ligand (acac = pentane-2,4-dionate), maintains a 1D polymeric structure in the solid state that limits its volatility and prevents solubility in non-coordinating solvents. The application of the unsymmetrical ligands, tbaoac (tert-butyl acetoacetate) and ptac (1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedionate), that exhibit different bridging properties at the two ends of the ligand, allowed us to change the connectivity pattern within the heterometallic assembly. The latter was demonstrated by structural characterization of heterometallic complexes LiFe(tbaoac) 3 (1) and LiFe(ptac) 3 (2) that consist of discrete heterocyclic tetranuclear molecules Li 2 Fe 2 L 6 . The compounds are highly volatile and exhibit a congruent sublimation character. DART mass spectrometric investigation revealed the presence of heterometallic molecules in the gas phase. The positive mode spectra are dominated by the presence of [M - L] + peaks (M = Li 2 Fe 2 L 6 ). In accord with their discrete molecular structure, complexes 1 and 2 are highly soluble in nearly all common solvents. In order to test the retention of the heterometallic structure in solution, the diamagnetic analog of 1, LiMg(tbaoac) 3 (4), has been isolated. Its tetranuclear molecular structure was found to be isomorphous to that of the iron counterpart. 1 H and 7 Li NMR spectroscopy unambiguously confirmed the presence of heterometallic molecules in solutions of non-coordinating solvents. The heterometallic precursor 1 was shown to exhibit clean thermal decomposition in air that results in phase-pure

  10. Methyl 3-[3',4'-(methylenedioxy)phenyl]-2-methyl glycidate: an ecstasy precursor seized in Sydney, Australia.

    PubMed

    Collins, Michael; Heagney, Aaron; Cordaro, Frank; Odgers, David; Tarrant, Gregory; Stewart, Samantha

    2007-07-01

    Five 44 gallon drums labeled as glycidyl methacrylate were seized by the Australian Customs Service and the Australian Federal Police at Port Botany, Sydney, Australia, in December 2004. Each drum contained a white, semisolid substance that was initially suspected to be 3,4-methylenedioxymethylamphetamine (MDMA). Gas chromatography-mass spectroscopy (GC/MS) analysis demonstrated that the material was neither glycidyl methacrylate nor MDMA. Because intelligence sources employed by federal agents indicated that this material was in some way connected to MDMA production, suspicion fell on the various MDMA precursor chemicals. Using a number of techniques including proton nuclear magnetic resonance spectroscopy ((1)H NMR), carbon nuclear magnetic resonance spectroscopy ((13)C NMR), GC/MS, infrared spectroscopy, and total synthesis, the unknown substance was eventually identified as methyl 3-[3',4'(methylenedioxy)phenyl]-2-methyl glycidate. The substance was also subjected to a published hydrolysis and decarboxylation procedure and gave a high yield of the MDMA precursor chemical, 3,4-methylenedioxyphenyl-2-propanone, thereby establishing this material as a "precursor to a precursor."

  11. Atomic Force Microscopy Study on the Stiffness of Nanosized Liposomes Containing Charged Lipids.

    PubMed

    Takechi-Haraya, Yuki; Goda, Yukihiro; Sakai-Kato, Kumiko

    2018-06-18

    It has recently been recognized that the mechanical properties of lipid nanoparticles play an important role during in vitro and in vivo behaviors such as cellular uptake, blood circulation, and biodistribution. However, there have been no quantitative investigations of the effect of commonly used charged lipids on the stiffness of nanosized liposomes. In this study, by means of atomic force microscopy (AFM), we quantified the stiffness of nanosized liposomes composed of neutrally charged lipids combined with positively or negatively charged lipids while simultaneously imaging the liposomes in aqueous medium. Our results showed that charged lipids, whether negatively or positively charged, have the effect of reducing the stiffness of nanosized liposomes, independently of the saturation degree of the lipid acyl chains; the measured stiffness values of liposomes containing charged lipids are 30-60% lower than those of their neutral counterpart liposomes. In addition, we demonstrated that the Laurdan generalized polarization values, which are related to the hydration degree of the liposomal membrane interface and often used as a qualitative indicator of liposomal membrane stiffness, do not directly correlate with the physical stiffness values of the liposomes prepared in this study. However, our results indicate that direct quantitative AFM measurement is a valuable method to gain molecular-scale information about how the hydration degree of liposomal interfaces reflects (or does not reflect) liposome stiffness as a macroscopic property. Our AFM method will contribute to the quantitative characterization of the nano-bio interaction of nanoparticles and to the optimization of the lipid composition of liposomes for clinical use.

  12. Self-assembled Ag nanoparticle network passivated by a nano-sized ZnO layer for transparent and flexible film heaters

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Seo, Ki-Won; Kim, Han-Ki, E-mail: imdlhkkim@khu.ac.kr; Kim, Min-Yi

    2015-12-15

    We investigated a self-assembled Ag nanoparticle network electrode passivated by a nano-sized ZnO layer for use in high-performance transparent and flexible film heaters (TFFHs). The low temperature atomic layer deposition of a nano-sized ZnO layer effectively filled the uncovered area of Ag network and improved the current spreading in the self-assembled Ag network without a change in the sheet resistance and optical transmittance as well as mechanical flexibility. The time-temperature profiles and heat distribution analysis demonstrate that the performance of the TFTH with the ZnO/Ag network is superior to that of a TFFH with Ag nanowire electrodes. In addition, themore » TFTHs with ZnO/Ag network exhibited better stability than the TFFH with a bare Ag network due to the effective current spreading through the nano-sized ZnO layer.« less

  13. The adsorption interaction of a rutin-biopolymer complex with nanosized silica particles

    NASA Astrophysics Data System (ADS)

    Fedyanina, T. V.; Barvinchenko, V. N.; Lipkovskaya, N. A.; Pogorelyi, V. K.

    2008-10-01

    The influence of complex formation with biopolymers on the optical and acid properties of natural flavonoid rutin was studied. The adsorption interaction of biologically active flavonoids from officinal plants with the surface of nanosized silica particles was found to depend on the chemical nature of the biopolymer and adsorbate and solution properties.

  14. Atomic layer deposition of metal sulfide thin films using non-halogenated precursors

    DOEpatents

    Martinson, Alex B. F.; Elam, Jeffrey W.; Pellin, Michael J.

    2015-05-26

    A method for preparing a metal sulfide thin film using ALD and structures incorporating the metal sulfide thin film. The method includes providing an ALD reactor, a substrate, a first precursor comprising a metal and a second precursor comprising a sulfur compound. The first and the second precursors are reacted in the ALD precursor to form a metal sulfide thin film on the substrate. In a particular embodiment, the metal compound comprises Bis(N,N'-di-sec-butylacetamidinato)dicopper(I) and the sulfur compound comprises hydrogen sulfide (H.sub.2S) to prepare a Cu.sub.2S film. The resulting metal sulfide thin film may be used in among other devices, photovoltaic devices, including interdigitated photovoltaic devices that may use relatively abundant materials for electrical energy production.

  15. Nano-sized, quaternary titanium(IV) metal-organic frameworks with multidentate ligands.

    PubMed

    Baranwal, Balram Prasad; Singh, Alok Kumar

    2010-12-01

    Some mononuclear nano-sized, quaternary titanium(IV) complexes having the general formula [Ti(acac)(OOCR)2(SB)] (where Hacac=acetylacetone, R=C15H31 or C17H35, HSB=Schiff bases) have been synthesized using different multidentate ligands. These were characterized by elemental analyses, molecular weight determinations and spectral (FTIR, 1H NMR and powder XRD) studies. Conductance measurement indicated their non-conducting nature which may behave like insulators. Structural parameters like the values of limiting indices h, k, l, cell constants a, b, c, angles α, β, γ and particle size are calculated from powder XRD data for complex 1 which indicated nano-sized triclinic system in them. Bidentate chelating nature of acetylacetone, carboxylate and Schiff base anions in the complexes was established by their infrared spectra. Molecular weight determinations confirmed mononuclear nature of the complexes. On the basis of physico-chemical studies, coordination number 8 was assigned for titanium(IV) in the complexes. Transmission electron microscopy (TEM) and the selected area electron diffraction (SAED) studies indicated spherical particles with poor crystallinity. Copyright © 2010 Elsevier B.V. All rights reserved.

  16. Twenty-Eight-Day Repeated Inhalation Toxicity Study of Nano-Sized Neodymium Oxide in Male Sprague-Dawley Rats

    PubMed Central

    Kim, Yong-Soon; Lim, Cheol-Hong; Shin, Seo-Ho; Kim, Jong-Choon

    2017-01-01

    Neodymium is a future-oriented material due to its unique properties, and its use is increasing in various industrial fields worldwide. However, the toxicity caused by repeated exposure to this metal has not been studied in detail thus far. The present study was carried out to investigate the potential inhalation toxicity of nano-sized neodymium oxide (Nd2O3) following a 28-day repeated inhalation exposure in male Sprague-Dawley rats. Male rats were exposed to nano-sized Nd2O3-containing aerosols via a nose-only inhalation system at doses of 0 mg/m3, 0.5 mg/m3, 2.5 mg/m3, and 10 mg/m3 for 6 hr/day, 5 days/week over a 28-day period, followed by a 28-day recovery period. During the experimental period, clinical signs, body weight, hematologic parameters, serum biochemical parameters, necropsy findings, organ weight, and histopathological findings were examined; neodymium distribution in the major organs and blood, bronchoalveolar lavage fluid (BALF), and oxidative stress in lung tissues were analyzed. Most of the neodymium was found to be deposited in lung tissues, showing a dose-dependent relationship. Infiltration of inflammatory cells and pulmonary alveolar proteinosis (PAP) were the main observations of lung histopathology. Infiltration of inflammatory cells was observed in the 2.5 mg/m3 and higher dose treatment groups. PAP was observed in all treatment groups accompanied by an increase in lung weight, but was observed to a lesser extent in the 0.5 mg/m3 treatment group. In BALF analysis, total cell counts, including macrophages and neutrophils, lactate dehydrogenase, albumin, interleukin-6, and tumor necrosis factor-alpha, increased significantly in all treatment groups. After a 4-week recovery period, these changes were generally reversed in the 0.5 mg/m3 group, but were exacerbated in the 10 mg/m3 group. The lowest-observed-adverse-effect concentration of nano-sized Nd2O3 was determined to be 0.5 mg/m3, and the target organ was determined to be the lung

  17. ACBC to Balcite: Bioinspired Synthesis of a Highly Substituted High-Temperature Phase from an Amorphous Precursor

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Whittaker, Michael L.; Joester, Derk

    2017-04-28

    Energy-efficient synthesis of materials locked in compositional and structural states far from equilibrium remains a challenging goal, yet biomineralizing organisms routinely assemble such materials with sophisticated designs and advanced functional properties, often using amorphous precursors. However, incorporation of organics limits the useful temperature range of these materials. Herein, the bioinspired synthesis of a highly supersaturated calcite (Ca0.5Ba0.5CO3) called balcite is reported, at mild conditions and using an amorphous calcium–barium carbonate (ACBC) (Ca1- x Ba x CO3·1.2H2O) precursor. Balcite not only contains 50 times more barium than the solubility limit in calcite but also displays the rotational disorder on carbonate sitesmore » that is typical for high-temperature calcite. It is significantly harder (30%) and less stiff than calcite, and retains these properties after heating to elevated temperatures. Analysis of balcite local order suggests that it may require the formation of the ACBC precursor and could therefore be an example of nonclassical nucleation. These findings demonstrate that amorphous precursor pathways are powerfully enabling and provide unprecedented access to materials far from equilibrium, including high-temperature modifications by room-temperature synthesis.« less

  18. Confined-plume chemical deposition: rapid synthesis of crystalline coatings of known hard or superhard materials on inorganic or organic supports by resonant IR decomposition of molecular precursors.

    PubMed

    Ivanov, Borislav L; Wellons, Matthew S; Lukehart, Charles M

    2009-08-26

    A one-step process for preparing microcrystalline coatings of known superhard, very hard, or ultraincompressible ceramic compositions on either inorganic or organic supports is reported. Midinfrared pulsed-laser irradiation of preceramic chemical precursors layered between IR-transmissive hard/soft supports under temporal and spatial confinement at a laser wavelength resonant with a precursor vibrational band gives one-step deposition of crystalline ceramic coatings without incurring noticeable collateral thermal damage to the support material. Reaction plume formation at the precursor/laser beam interface initiates confined-plume, chemical deposition (CPCD) of crystalline ceramic product. Continuous ceramic coatings are produced by rastering the laser beam over a sample specimen. CPCD processing of the Re-B single-source precursor, (B(3)H(8))Re(CO)(4), the dual-source mixtures, Ru(3)(CO)(12)/B(10)H(14) or W(CO)(6)/B(10)H(14), and the boron/carbon single-source precursor, o-B(10)C(2)H(12), confined between Si wafer or NaCl plates gives microcrystalline deposits of ReB(2), RuB(2), WB(4), or B(4)C, respectively. CPCD processing of Kevlar fabric wetted by (B(3)H(8))Re(CO)(4) produces an oriented, microcrystalline coating of ReB(2) on the Kevlar fabric without incurring noticeable thermal damage of the polymer support. Similarly, microcrystalline coatings of ReB(2) can be formed on IR-transmissive IR2, Teflon, or Ultralene polymer films.

  19. Modeling precursor diffusion and reaction of atomic layer deposition in porous structures

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Keuter, Thomas, E-mail: t.keuter@fz-juelich.de; Menzler, Norbert Heribert; Mauer, Georg

    2015-01-01

    Atomic layer deposition (ALD) is a technique for depositing thin films of materials with a precise thickness control and uniformity using the self-limitation of the underlying reactions. Usually, it is difficult to predict the result of the ALD process for given external parameters, e.g., the precursor exposure time or the size of the precursor molecules. Therefore, a deeper insight into ALD by modeling the process is needed to improve process control and to achieve more economical coatings. In this paper, a detailed, microscopic approach based on the model developed by Yanguas-Gil and Elam is presented and additionally compared with themore » experiment. Precursor diffusion and second-order reaction kinetics are combined to identify the influence of the porous substrate's microstructural parameters and the influence of precursor properties on the coating. The thickness of the deposited film is calculated for different depths inside the porous structure in relation to the precursor exposure time, the precursor vapor pressure, and other parameters. Good agreement with experimental results was obtained for ALD zirconiumdioxide (ZrO{sub 2}) films using the precursors tetrakis(ethylmethylamido)zirconium and O{sub 2}. The derivation can be adjusted to describe other features of ALD processes, e.g., precursor and reactive site losses, different growth modes, pore size reduction, and surface diffusion.« less

  20. Photodegradation of surfactants on the nanosized TiO2 prepared by hydrolysis of the alkoxide titanium.

    PubMed

    Zhang, Rubing; Gao, Lian; Zhang, Qinghong

    2004-01-01

    Nanosized TiO(2) was synthesized by hydrolysis of titanium tetraisopropoxide in the nanodroplets of microemulsions. The microemulsion provided by functionalized surfactants derived from the mixture of the commercially available sodium dodecylbenzensulfonate (DBS) and sodium dodecyl sulfate (DS). The resulting TiO(2) nanoparticles were characterized by transmission electron microscopy, X-ray diffraction, and differential thermal analysis. Nanosized TiO(2) of anatase was found to show good photocatalytic properties in the photodegradation of DBS and DS surfactants. The cleavage of the aromatic moiety, the intermediate products and ultimate mineralization to CO(2) were examined in the process of photodegradation. A mechanism is also proposed on the basis of these experimental results.

  1. Solution combustion synthesis and characterization of nanosized bismuth ferrite

    NASA Astrophysics Data System (ADS)

    Sai Kumar, V. Sesha; Rao, K. Venkateswara; Krishnaveni, T.; Kishore Goud, A. Shiva; Reddy, P. Ranjith

    2012-06-01

    The present paper describes a simple method of nanosized BiFeO3 by the solution combustion synthesis using bismuth and iron nitrates as oxidizers and the combination fuel of citric acid and ammonium hydroxide, with fuel to oxidizer ratio (Ψ = 1) one. The X-ray Diffraction results indicated rhombohedral phase (R3m) with JCPDS data card no: 72-2035. The ferroelectric transition of the sample at 8310C was detected by differential thermal analysis. Thermal analysis was done by Thermal gravimetric-Differential thermal analyzer and obtained results were presented in this paper.

  2. Plasma Methods of Obtainment of Multifunctional Composite Materials, Dispersion-Hardened by Nanoparticles

    NASA Astrophysics Data System (ADS)

    Sizonenko, O. N.; Grigoryev, E. G.; Pristash, N. S.; Zaichenko, A. D.; Torpakov, A. S.; Lypian, Ye. V.; Tregub, V. A.; Zholnin, A. G.; Yudin, A. V.; Kovalenko, A. A.

    2017-09-01

    High voltage electric discharge (HVED) in disperse system "hydrocarbon liquid - powder" due to impact of plasma discharge channel, electromagnetic fields, shock waves mechanical impact, hydro flows and volume microcavitation leads to synthesis of nanocarbon, metal powders dispersion and synthesis of micro- (from 10-6 to 10-7 m) and nanosized (from 10-7 to 10-9 m) composite powders of hardening phases. Spark plasma sintering (SPS) of powder mixtures allows targeted control of grain growth rate and thus allows obtainment of multifunctional composite materials dispersion hardened by nanoparticles. Processes of HVED synthesis of micro- and nanosized powders of new compositions from elemental metal powders and their mixtures with the subsequent application of high-speed SPS of obtained powders create conditions for increase of strength (by 10-20 %), hardness and wear-resistance (by 30-60 %) of obtained materials.

  3. The Pursuit of a Scalable Nanofabrication Platform for Use in Material and Life Science Applications

    PubMed Central

    GRATTON, STEPHANIE E. A.; WILLIAMS, STUART S.; NAPIER, MARY E.; POHLHAUS, PATRICK D.; ZHOU, ZHILIAN; WILES, KENTON B.; MAYNOR, BENJAMIN W.; SHEN, CLIFTON; OLAFSEN, TOVE; SAMULSKI, EDWARD T.; DESIMONE, JOSEPH M.

    2008-01-01

    CONSPECTUS In this Account, we describe the use of perfluoropolyether (PFPE)-based materials that are able to accurately mold and replicate micro- and nanosized features using traditional techniques such as embossing as well as new techniques that we developed to exploit the exceptional surface characteristics of fluorinated substrates. Because of the unique partial wetting and nonwetting characteristics of PFPEs, we were able to go beyond the usual molding and imprint lithography approaches and have created a technique called PRINT (Particle [or Pattern] Replication In Nonwetting Templates). PRINT is a distinctive “top-down” fabrication technique capable of generating isolated particles, arrays of particles, and arrays of patterned features for a plethora of applications in both nanomedicine and materials science. A particular strength of the PRINT technology is the high-resolution molding of well-defined particles with precise control over size, shape, deformability, and surface chemistry. The level of replication obtained showcases some of the unique characteristics of PFPE molding materials. In particular, these materials arise from very low surface energy precursors with positive spreading coefficients, can be photocured at ambient temperature, and are minimally adhesive, nonswelling, and conformable. These distinctive features enable the molding of materials with unique attributes and nanometer resolution that have unprecedented scientific and technological value. For example, in nanomedicine, the use of PFPE materials with the PRINT technique allows us to design particles in which we can tailor key therapeutic parameters such as bioavailability, biodistribution, target-specific cell penetration, and controlled cargo release. Similarly, in materials science, we can fabricate optical films and lens arrays, replicate complex, naturally occurring objects such as adenovirus particles, and create 2D patterned arrays of inorganic oxides. PMID:18720952

  4. Annealing of aromatic polyimide precursors

    NASA Technical Reports Server (NTRS)

    Wakelyn, N. T.

    1975-01-01

    A study has been made of the thermal behavior of polyimide precursors: an isomeric pair of crystals of the complex formed by p-phenylenediamine with the separated isomers of the di-isopropyl ester of pyromellitic acid. Specimens of this material were isothermally annealed in the temperature range 120 C to 170 C for periods of time up to 1 week. Although this temperature range is well below that customarily used for imidizations, the working hypothesis was that it would be more likely that a polymer embodying at least part of the precursor structure could be formed if the molecular motion was minimized to that actually required for the formation of the imide linkage. The progress of the annealing was followed by: infrared spectroscopy, differential thermal analysis, powder X-ray diffraction, and thermal gravimetric analysis. Single crystal X-ray analysis of the meta monomer yields a structure of chains of alternating acid and base and suggests that this monomer is amenable to polymerization with a minimum of geometrical disruption.

  5. Superior performance of nanoscaled Fe3O4 as anode material promoted by mosaicking into porous carbon framework

    NASA Astrophysics Data System (ADS)

    Wan, Wang; Wang, Chao; Zhang, Weidong; Chen, Jitao; Zhou, Henghui; Zhang, Xinxiang

    2014-01-01

    A nanoscale Fe3O4/porous carbon-multiwalled carbon nanotubes (MWCNTs) composite is synthesized through a simple hard-template method by using Fe2O3 nanoparticles as the precursor and SiO2 nanoparticles as the template. The composite shows good cycle performance (941 mAh g-1 for the first cycle at 0.1 C, with 106% capacity retention at the 80th cycle) and high rate capability (71% capacity retained at 5 C rate). Its excellent electrical properties can be attributed to the porous carbon framework structure, which is composed of carbon and MWCNTs. In this composite, the porous structure provides space for the change in Fe3O4 volume during cycling and shortens the lithium ion diffusion distance, the MWCNTs increase the electron conductivity, and the carbon coating reduces the risk of side reactions. The results provide clear evidences for the utility of porous carbon framework to improve the electrochemical performances of nanosized transition-metal oxides as anode materials for lithium-ion batteries.

  6. From Solute, Fluidic and Particulate Precursors to Complex Organizations of Matter.

    PubMed

    Rao, Ashit; Cölfen, Helmut

    2018-03-24

    The organization of matter from its constitutive units recruits intermediate states with distinctive degrees of self-association and molecular order. Existing as clusters, droplets, gels as well as amorphous and crystalline nanoparticles, these precursor forms have fundamental contributions towards the composition and structure of inorganic and organic architectures. In this personal account, we show that the transitions from atoms, molecules or ionic species to superstructures of higher order are intertwined with the interfaces and interactions of precursor and intermediate states. Structural organizations distributed across different length scales are explained by the multistep nature of nucleation and crystallization, which can be guided towards functional hybrid materials by the strategic application of additives, templates and reaction environments. Thus, the non-classical pathways for material formation and growth offer conceptual frameworks for elucidating, inducing and directing fascinating material organizations of biogenic and synthetic origins. © 2018 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Lignin from Micro- to Nanosize: Applications

    PubMed Central

    Friedl, Anton

    2017-01-01

    Micro- and nanosize lignin has recently gained interest due to improved properties compared to standard lignin available today. As the second most abundant biopolymer after cellulose, lignin is readily available but used for rather low-value applications. This review focuses on the application of micro- and nanostructured lignin in final products or processes that all show potential for high added value. The fields of application are ranging from improvement of mechanical properties of polymer nanocomposites, bactericidal and antioxidant properties and impregnations to hollow lignin drug carriers for hydrophobic and hydrophilic substances. Also, a carbonization of lignin nanostructures can lead to high-value applications such as use in supercapacitors for energy storage. The properties of the final product depend on the surface properties of the nanomaterial and, therefore, on factors like the lignin source, extraction method, and production/precipitation methods, as discussed in this review. PMID:29117142

  8. Nano-sized Contrast Agents to Non-Invasively Detect Renal Inflammation by Magnetic Resonance Imaging

    PubMed Central

    Thurman, Joshua M.; Serkova, Natalie J.

    2013-01-01

    Several molecular imaging methods have been developed that employ nano-sized contrast agents to detect markers of inflammation within tissues. Renal inflammation contributes to disease progression in a wide range of autoimmune and inflammatory diseases, and a biopsy is currently the only method of definitively diagnosing active renal inflammation. However, the development of new molecular imaging methods that employ contrast agents capable of detecting particular immune cells or protein biomarkers will allow clinicians to evaluate inflammation throughout the kidneys, and to assess a patient's response to immunomodulatory drugs. These imaging tools will improve our ability to validate new therapies and to optimize the treatment of individual patients with existing therapies. This review describes the clinical need for new methods of monitoring renal inflammation, and recent advances in the development of nano-sized contrast agents for detection of inflammatory markers of renal disease. PMID:24206601

  9. Synthesis and improved explosion behaviors of aluminum powders coated with nano-sized nickel film

    NASA Astrophysics Data System (ADS)

    Kim, Kyung Tae; Kim, Dong Won; Kim, Soo Hyung; Kim, Chang Kee; Choi, Yoon Jeong

    2017-09-01

    Nickel (Ni) materials with a thickness of a few hundred nm were homogeneously coated on the surfaces of aluminum (Al) powders by an electroless plating process. The Ni-coated Al powders show characteristic interfacial structures mixed of Ni, Al and O instead of densely packed Al oxide at the surface. The explosion test of the Ni-coated Al powders utilizing flame ignition showed that the powders had a 3.6 times enhanced pressurization rate of 405 kPa/ms compared to 111 kPa/ms of uncoated Al powders. It was found that this is due to a feasible diffusion of oxygen atoms into the Al powders through the thin and rough interfacial layers present at the Ni/Al interface. These results clearly indicate that nano-sized Ni film introduced instead of surface oxide acts as a very profitable layer to achieve efficient combustion behaviors by a rapid oxidation of Al powders.

  10. Thermal conductivity enhancement and sedimentation reduction of magnetorheological fluids with nano-sized Cu and Al additives

    NASA Astrophysics Data System (ADS)

    Rahim, M. S. A.; Ismail, I.; Choi, S. B.; Azmi, W. H.; Aqida, S. N.

    2017-11-01

    This work presents enhanced material characteristics of smart magnetorheological (MR) fluids by utilizing nano-sized metal particles. Especially, enhancement of thermal conductivity and reduction of sedimentation rate of MR fluids those are crucial properties for applications of MR fluids are focussed. In order to achieve this goal, a series of MR fluid samples are prepared using carbonyl iron particles (CIP) and hydraulic oil, and adding nano-sized particles of copper (Cu), aluminium (Al), and fumed silica (SiO2). Subsequently, the thermal conductivity is measured by the thermal property analyser and the sedimentation of MR fluids is measured using glass tubes without any excitation for a long time. The measured thermal conductivity is then compared with theoretical models such as Maxwell model at various CIP concentrations. In addition, in order to show the effectiveness of MR fluids synthesized in this work, the thermal conductivity of MRF-132DG which is commercially available is measured and compared with those of the prepared samples. It is observed that the thermal conductivity of the samples is much better than MRF-132DG showing the 148% increment with 40 vol% of the magnetic particles. It is also observed that the sedimentation rate of the prepared MR fluid samples is less than that of MRF-132DG showing 9% reduction with 40 vol% of the magnetic particles. The mixture optimized sample with high conductivity and low sedimentation was also obtained. The magnetization of the sample recorded an enhancement of 70.5% when compared to MRF-132DG. Furthermore, the shear yield stress of the sample were also increased with and without the influence of magnetic field.

  11. Strategy for chemotherapeutic delivery using a nanosized porous metal-organic framework with a central composite design.

    PubMed

    Li, Yingpeng; Li, Xiuyan; Guan, Qingxia; Zhang, Chunjing; Xu, Ting; Dong, Yujing; Bai, Xinyu; Zhang, Weiping

    2017-01-01

    Enhancing drug delivery is an ongoing endeavor in pharmaceutics, especially when the efficacy of chemotherapy for cancer is concerned. In this study, we prepared and evaluated nanosized HKUST-1 (nanoHKUST-1), nanosized metal-organic drug delivery framework, loaded with 5-fluorouracil (5-FU) for potential use in cancer treatment. NanoHKUST-1 was prepared by reacting copper (II) acetate [Cu(OAc) 2 ] and benzene-1,3,5-tricarboxylic acid (H 3 BTC) with benzoic acid (C 6 H 5 COOH) at room temperature (23.7°C±2.4°C). A central composite design was used to optimize 5-FU-loaded nanoHKUST-1. Contact time, ethanol concentration, and 5-FU:material ratios were the independent variables, and the entrapment efficiency of 5-FU was the response parameter measured. Powder X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption were used to determine the morphology of nanoHKUST-1. In addition, 5-FU release studies were conducted, and the in vitro cytotoxicity was evaluated. Entrapment efficiency and drug loading were 9.96% and 40.22%, respectively, while the small-angle X-ray diffraction patterns confirmed a regular porous structure. The SEM and TEM images of the nanoHKUST-1 confirmed the presence of round particles (diameter: approximately 100 nm) and regular polygon arrays of mesoporous channels of approximately 2-5 nm. The half-maximal lethal concentration (LC 50 ) of the 5-FU-loaded nanoHKUST-1 was approximately 10 µg/mL. The results indicated that nanoHKUST-1 is a potential vector worth developing as a cancer chemotherapeutic drug delivery system.

  12. Low-Temperature Molecular Layer Deposition Using Monofunctional Aromatic Precursors and Ozone-Based Ring-Opening Reactions.

    PubMed

    Svärd, Laura; Putkonen, Matti; Kenttä, Eija; Sajavaara, Timo; Krahl, Fabian; Karppinen, Maarit; Van de Kerckhove, Kevin; Detavernier, Christophe; Simell, Pekka

    2017-09-26

    Molecular layer deposition (MLD) is an increasingly used deposition technique for producing thin coatings consisting of purely organic or hybrid inorganic-organic materials. When organic materials are prepared, low deposition temperatures are often required to avoid decomposition, thus causing problems with low vapor pressure precursors. Monofunctional compounds have higher vapor pressures than traditional bi- or trifunctional MLD precursors, but do not offer the required functional groups for continuing the MLD growth in subsequent deposition cycles. In this study, we have used high vapor pressure monofunctional aromatic precursors in combination with ozone-triggered ring-opening reactions to achieve sustained sequential growth. MLD depositions were carried out by using three different aromatic precursors in an ABC sequence, namely with TMA + phenol + O 3 , TMA + 3-(trifluoromethyl)phenol + O 3 , and TMA + 2-fluoro-4-(trifluoromethyl)benzaldehyde + O 3 . Furthermore, the effect of hydrogen peroxide as a fourth step was evaluated for all studied processes resulting in a four-precursor ABCD sequence. According to the characterization results by ellipsometry, infrared spectroscopy, and X-ray reflectivity, self-limiting MLD processes could be obtained between 75 and 150 °C with each of the three aromatic precursors. In all cases, the GPC (growth per cycle) decreased with increasing temperature. In situ infrared spectroscopy indicated that ring-opening reactions occurred in each ABC sequence. Compositional analysis using time-of-flight elastic recoil detection indicated that fluorine could be incorporated into the film when 3-(trifluoromethyl)phenol and 2-fluoro-4-(trifluoromethyl)benzaldehyde were used as precursors.

  13. Review on recent progress of nanostructured anode materials for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Goriparti, Subrahmanyam; Miele, Ermanno; De Angelis, Francesco; Di Fabrizio, Enzo; Proietti Zaccaria, Remo; Capiglia, Claudio

    2014-07-01

    This review highlights the recent research advances in active nanostructured anode materials for the next generation of Li-ion batteries (LIBs). In fact, in order to address both energy and power demands of secondary LIBs for future energy storage applications, it is required the development of innovative kinds of electrodes. Nanostructured materials based on carbon, metal/semiconductor, metal oxides and metal phosphides/nitrides/sulfides show a variety of admirable properties for LIBs applications such as high surface area, low diffusion distance, high electrical and ionic conductivity. Therefore, nanosized active materials are extremely promising for bridging the gap towards the realization of the next generation of LIBs with high reversible capacities, increased power capability, long cycling stability and free from safety concerns. In this review, anode materials are classified, depending on their electrochemical reaction with lithium, into three groups: intercalation/de-intercalation, alloy/de-alloy and conversion materials. Furthermore, the effect of nanoscale size and morphology on the electrochemical performance is presented. Synthesis of the nanostructures, lithium battery performance and electrode reaction mechanisms are also discussed. To conclude, the main aim of this review is to provide an organic outline of the wide range of recent research progresses and perspectives on nanosized active anode materials for future LIBs.

  14. Electrical and magnetic properties of nano-sized magnesium ferrite

    NASA Astrophysics Data System (ADS)

    T, Smitha; X, Sheena; J, Binu P.; Mohammed, E. M.

    2015-02-01

    Nano-sized magnesium ferrite was synthesized using sol-gel techniques. Structural characterization was done using X-ray diffractometer and Fourier Transform Infrared Spectrometer. Vibration Sample Magnetometer was used to record the magnetic measurements. XRD analysis reveals the prepared sample is single phasic without any impurity. Particle size calculation shows the average crystallite size of the sample is 19nm. FTIR analysis confirmed spinel structure of the prepared samples. Magnetic measurement study shows that the sample is ferromagnetic with high degree of isotropy. Hysterisis loop was traced at temperatures 100K and 300K. DC electrical resistivity measurements show semiconducting nature of the sample.

  15. Interactions Between Nanosized Materials and the Brain

    PubMed Central

    Simkó, M; Mattsson, Mats-Olof

    2014-01-01

    The current rapid development of nanotechnologies and engineered nanomaterials (ENM) will impact the society in a major fashion during the coming decades. This development also causes substantial safety concerns. Among the many promising applications of ENM, products that can be used for diagnosis and treatment of diseases, including conditions that affect the nervous system, are under development. ENM can pass the blood brain barrier (BBB) and accumulate within the brain. It seems that the nano-form rather than the bulk form of the chemicals pass the BBB, and that there is an inverse relationship between particle size and the ability to penetrate the BBB. Although translocation of ENM to the brain is possible during experimental conditions, the health relevance for real-life situations is far from clear. One major reason for this is that studies have been using nanoparticle concentrations that are far higher than the ones that can be expected during realistic exposures. However, very high exposure to the CNS can cause effects on neurotransmission, redox homeostasis and behavior. Available studies have been focusing on possible effects of the first generation of ENM. It will be necessary to study possible health effects also of expected novel sophisticated materials, independent of the outcome of present studies. The prospects for intended or targeted medical applications are promising since it has been shown that ENM can be made to pass the BBB and reach specific regions or cells within the brain. PMID:25039776

  16. Superconducting MgB2 films via precursor postprocessing approach

    NASA Astrophysics Data System (ADS)

    Paranthaman, M.; Cantoni, C.; Zhai, H. Y.; Christen, H. M.; Aytug, T.; Sathyamurthy, S.; Specht, E. D.; Thompson, J. R.; Lowndes, D. H.; Kerchner, H. R.; Christen, D. K.

    2001-06-01

    Superconducting MgB2 films with Tc=38.6 K were prepared using a precursor-deposition, ex situ postprocessing approach. Precursor films of boron, ˜0.5 μm thick, were deposited onto Al2O3 (102) substrates by electron-beam evaporation; a postanneal at 890 °C in the presence of bulk MgB2 and Mg metal produced highly crystalline MgB2 films. X-ray diffraction indicated that the films exhibit some degree of c-axis alignment, but are randomly oriented in plane. Transport current measurements of the superconducting properties show high values of the critical current density and yield an irreversibility line that exceeds that determined by magnetic measurements on bulk polycrystalline materials.

  17. Novel materials for electronic device fabrication using ink-jet printing technology

    NASA Astrophysics Data System (ADS)

    Kumashiro, Yasushi; Nakako, Hideo; Inada, Maki; Yamamoto, Kazunori; Izumi, Akira; Ishihara, Masamichi

    2009-11-01

    Novel materials and a metallization technique for the printed electronics were studied. Insulator inks and conductive inks were investigated. For the conductive ink, the nano-sized copper particles were used as metallic sources. These particles were prepared from a copper complex by a laser irradiation process in the liquid phase. Nano-sized copper particles were consisted of a thin copper oxide layer and a metal copper core wrapped by the layer. The conductive ink showed good ink-jettability. In order to metallize the printed trace of the conductive ink on a substrate, the atomic hydrogen treatment was carried out. Atomic hydrogen was generated on a heated tungsten wire and carried on the substrate. The temperature of the substrate was up to 60 °C during the treatment. After the treatment, the conductivity of a copper trace was 3 μΩ cm. It was considered that printed wiring boards can be easily fabricated by employing the above materials.

  18. New high boron content polyborane precursors to advanced ceramic materials: New syntheses, new applications

    NASA Astrophysics Data System (ADS)

    Guron, Marta

    There is a need for new synthetic routes to high boron content materials for applications as polymeric precursors to ceramics, as well as in neutron shielding and potential medical applications. To this end, new ruthenium-catalyzed olefin metathesis routes have been devised to form new complex polyboranes and polymeric species. Metathesis of di-alkenyl substituted o-carboranes allowed the synthesis of ring-closed products fused to the carborane cage, many of which are new compounds and one that offers a superior synthetic method to one previously published. Acyclic diene metathesis of di-alkenyl substituted m-carboranes resulted in the formation of new main-chain carborane-containing polymers of modest molecular weights. Due to their extremely low char yields, and in order to explore other metathesis routes, ring opening metathesis polymerization (ROMP) was used to generate the first examples of poly(norbornenyl- o-carboranes). Monomer synthesis was achieved via a two-step process, incorporating Ti-catalyzed hydroboration to make 6-(5-norbornenyl)-decaborane, followed by alkyne insertion in ionic liquid media to achieve 1,2-R2 -3-norbornenyl o-carborane species. The monomers were then polymerized using ROMP to afford several examples of poly(norbornenyl- o-carboranes) with relatively high molecular weights. One such polymer, [1-Ph, 3-(=CH2-C5H7-CH2=)-1,2-C 2B10H10]n, had a char yield very close to the theoretical char yield of 44%. Upon random copolymerization with poly(6-(5-norbornenyl) decaborane), char yields significantly increased to 80%, but this number was well above the theoretical value implicating the formation of a boron-carbide/carbon ceramic. Finally, applications of polyboranes were explored via polymer blends toward the synthesis of ceramic composites and the use of polymer precursors as reagents for potential ultra high temperature ceramic applications. Upon pyrolysis, polymer blends of poly(6-(5-norbornenyl)-decaborane) and poly

  19. Migration of nanosized layered double hydroxide platelets from polylactide nanocomposite films.

    PubMed

    Schmidt, B; Katiyar, V; Plackett, D; Larsen, E H; Gerds, N; Koch, C Bender; Petersen, J H

    2011-01-01

    Melt-extruded L-polylactide (PLA) nanocomposite films were prepared from commercially available PLA and laurate-modified Mg-Al layered double hydroxide (LDH-C12). Three films were tested for total migration as well as specific migration of LDH, tin, laurate and low molecular weight PLA oligomers (OLLA). This is the first reported investigation on the migration properties of PLA-LDH nanocomposite films. The tests were carried out as part of an overall assessment of the suitability of such films for use as food contact materials (FCM). Total migration was determined according to a European standard method. All three films showed migration of nanosized LDH, which was quantified using acid digestion followed by inductively coupled plasma mass spectrometric (ICP-MS) detection of (26)Mg. Migration of LDH from the films was also confirmed by examining migrates using transmission electron microscopy (TEM) and was attributed indirectly to the significant PLA molecular weight reduction observed in extruded PLA-LDH-C12 films. Migration of tin was detected in two of the film samples prepared by dispersion of LDH-C12 using a masterbatch technique and migration of the laurate organomodifier took place from all three film types. The results indicate that the material properties are in compliance with the migration limits for total migration and specific lauric acid migration as set down by the EU legislation for FCM, at least if a reduction factor for fresh meat is taken into consideration. The tin detected arises from the use of organotin catalysts in the manufacture of PLA.

  20. Boron/Carbon/Silicon/Nitrogen Ceramics And Precursors

    NASA Technical Reports Server (NTRS)

    Riccitiello, Salvatore; Hsu, Ming TA; Chen, Timothy S.

    1996-01-01

    Ceramics containing various amounts of boron, carbon, silicon, and nitrogen made from variety of polymeric precursors. Synthesized in high yield from readily available and relatively inexpensive starting materials. Stable at room temperature; when polymerized, converted to ceramics in high yield. Ceramics resist oxidation and other forms of degradation at high temperatures; used in bulk to form objects or to infiltrate other ceramics to obtain composites having greater resistance to oxidation and high temperatures.

  1. Mesoporous metal oxides and processes for preparation thereof

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Suib, Steven L.; Poyraz, Altug Suleyman

    A process for preparing a mesoporous metal oxide, i.e., transition metal oxide. Lanthanide metal oxide, a post-transition metal oxide and metalloid oxide. The process comprises providing an acidic mixture comprising a metal precursor, an interface modifier, a hydrotropic ion precursor, and a surfactant; and heating the acidic mixture at a temperature and for a period of time sufficient to form the mesoporous metal oxide. A mesoporous metal oxide prepared by the above process. A method of controlling nano-sized wall crystallinity and mesoporosity in mesoporous metal oxides. The method comprises providing an acidic mixture comprising a metal precursor, an interface modifier,more » a hydrotropic ion precursor, and a surfactant; and heating the acidic mixture at a temperature and for a period of time sufficient to control nano-sized wall crystallinity and mesoporosity in the mesoporous metal oxides. Mesoporous metal oxides and a method of tuning structural properties of mesoporous metal oxides.« less

  2. Nanocrystalline CuInS2 And CuInSe2 via Low-Temperature Pyrolysis Of Single-Source Molecular Precursors

    NASA Technical Reports Server (NTRS)

    Castro, Stephanie L.; Bailey, Sheila G.; Raffaelle, Ryne P.; Banger, Kulbinder K.; Hepp, Aloysius F.

    2002-01-01

    Single-source precursors are molecules which contain all the necessary elements for synthesis of a desired material. Thermal decomposition of the precursor results in the formation of the material with the correct stoichiometry, as a nanocrystalline powder or a thin film. Nanocrystalline materials hold potential as components of next-generation Photovoltaic (PV) devices. Presented here are the syntheses of CuInS2 and CuInSe2 nanocrystals from the precursors (PPh3)2CuIn(SEt)4 and (PPh3)2CuIn(SePh)4, respectively. The size of the nanocrystals varies with the reaction temperature; a minimum of 200 C is required for the formation of the smallest CuInS2 crystals (approximately 1.6 nm diameter); at 300 C, crystals are approximately 7 nm.

  3. Aloe vera Induced Biomimetic Assemblage of Nucleobase into Nanosized Particles

    PubMed Central

    Chauhan, Arun; Zubair, Swaleha; Sherwani, Asif; Owais, Mohammad

    2012-01-01

    Aim Biomimetic nano-assembly formation offers a convenient and bio friendly approach to fabricate complex structures from simple components with sub-nanometer precision. Recently, biomimetic (employing microorganism/plants) synthesis of metal and inorganic materials nano-particles has emerged as a simple and viable strategy. In the present study, we have extended biological synthesis of nano-particles to organic molecules, namely the anticancer agent 5-fluorouracil (5-FU), using Aloe vera leaf extract. Methodology The 5-FU nano- particles synthesized by using Aloe vera leaf extract were characterized by UV, FT-IR and fluorescence spectroscopic techniques. The size and shape of the synthesized nanoparticles were determined by TEM, while crystalline nature of 5-FU particles was established by X-ray diffraction study. The cytotoxic effects of 5-FU nanoparticles were assessed against HT-29 and Caco-2 (human adenocarcinoma colorectal) cell lines. Results Transmission electron microscopy and atomic force microscopic techniques confirmed nano-size of the synthesized particles. Importantly, the nano-assembled 5-FU retained its anticancer action against various cancerous cell lines. Conclusion In the present study, we have explored the potential of biomimetic synthesis of nanoparticles employing organic molecules with the hope that such developments will be helpful to introduce novel nano-particle formulations that will not only be more effective but would also be devoid of nano-particle associated putative toxicity constraints. PMID:22403622

  4. Fabricating porous materials using interpenetrating inorganic-organic composite gels

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Seo, Dong-Kyun; Volosin, Alex

    Porous materials are fabricated using interpenetrating inorganic-organic composite gels. A mixture or precursor solution including an inorganic gel precursor, an organic polymer gel precursor, and a solvent is treated to form an inorganic wet gel including the organic polymer gel precursor and the solvent. The inorganic wet gel is then treated to form a composite wet gel including an organic polymer network in the body of the inorganic wet gel, producing an interpenetrating inorganic-organic composite gel. The composite wet gel is dried to form a composite material including the organic polymer network and an inorganic network component. The composite materialmore » can be treated further to form a porous composite material, a porous polymer or polymer composite, a porous metal oxide, and other porous materials.« less

  5. Insulation Materials Comprising Fibers Having a Partially Cured Polymer Coating Thereon, Articles Including Such Insulation Materials, and Methods of Forming Such Materials and Articles

    NASA Technical Reports Server (NTRS)

    Morgan, Richard E. (Inventor); Meeks, Craig L. (Inventor)

    2017-01-01

    Insulation materials have a coating of a partially cured polymer on a plurality of fibers, and the plurality of coated fibers in a cross-linked polymeric matrix. Insulation may be formed by applying a preceramic polymer to a plurality of fibers, heating the preceramic polymer to form a partially cured polymer over at least portions of the plurality of fibers, disposing the plurality of fibers in a polymeric material, and curing the polymeric material. A rocket motor may be formed by disposing a plurality of coated fibers in an insulation precursor, curing the insulation precursor to form an insulation material without sintering the partially cured polymer, and providing an energetic material over the polymeric material. An article includes an insulation material over at least one surface.

  6. [Study on anti-coagulant property of radio frequency sputtering nano-sized TiO2 thin films].

    PubMed

    Tang, Xiaoshan; Li, Da

    2010-12-01

    Nano-TiO2 thin films were prepared by Radio frequency (RF) sputtering on pyrolytic carbon substrates. The influences of sputtering power on the structure and the surface morphology of TiO2 thin films were investigated by X-ray diffraction (XRD), and by scanning electron microscopy (SEM). The results show that the TiO2 films change to anatase through the optimum of sputtering power. The mean diameter of nano-particle is about 30 nm. The anti-coagulant property of TiO2 thin films was observed through platelet adhesion in vitro. The result of experiment reveals the amount of thrombus on the TiO2 thin films being much less than that on the pyrolytic carbon. It also indicates that the RF sputtering Nano-sized TiO2 thin films will be a new kind of promising materials applied to artificial heart valve and endovascular stent.

  7. High magnetization Fe-Co and Fe-Ni submicron and nanosize particles by thermal decomposition and hydrogen reduction

    NASA Astrophysics Data System (ADS)

    Cui, B. Z.; Marinescu, M.; Liu, J. F.

    2014-05-01

    This paper reports morphology, structure, and magnetic properties of air-stable soft magnetic FexCo100-x (x = 65, 50, and 34) and Fe50Ni50 (at. %) submicron and nanosize particles fabricated by template-free thermal decomposition of nitrates of Fe, Co, and Ni and subsequent hydrogen reduction. The particle compositions were tuned by modification of the precursor solution concentrations. The as-synthesized Fe-Co and Fe50Ni50 particles have body centered cubic and face centered cubic poly-nanocrystalline structures, respectively. The Fe-Co and Fe50Ni50 particles have particle sizes in the range of 28-200 nm and 70-480 nm, and average grain sizes of 16-29 nm and 20-24 nm, respectively. The particle and grain sizes were controlled by tuning particle composition, and the temperature and time of hydrogen reduction. Saturation magnetization Ms as high as 207-224 emu/g and intrinsic coercivity Hci of 59-228 Oe were obtained in the Fe-Co particles reduced at 550 °C for 90 min. Of special note, the Ms of 224 emu/g (˜2.3 T) obtained in the Fe65Co35 particles is among the highest values for Fe-Co particles reported so far. Ms of 135-137 emu/g and Hci of 59-111 Oe were obtained in the Fe50Ni50 particles reduced at 500 or 550 °C for 20 min.

  8. Effects of Residual Lithium in the precursors of Li[Ni1/3Co1/3Mn1/3]O2 on their lithium-ion battery performance

    NASA Astrophysics Data System (ADS)

    Jo, Minsang; Ku, Heesuk; Park, Sanghyuk; Song, Junho; Kwon, Kyungjung

    2018-07-01

    Li[Ni1/3Co1/3Mn1/3]O2 cathode active materials are synthesized from co-precipitated hydroxide precursors Lix[Ni1/3Co1/3Mn1/3]1-x(OH)2, and the effect of residual Li in the precursors on the lithium-ion battery (LIB) performance of their corresponding cathode active materials is investigated. Three kinds of precursors that contain different amounts of Li are selected depending on different conditions of the solution composition for the co-precipitation and washing process. It is confirmed that the introduction of Li to the precursors reduces the degree of structural perfection by X-ray diffraction analysis. Undesirable cation mixing occurs with the increasing Li content of the precursors, which is inferred from a decline in lattice parameters and the calculated intensity ratio of (003) and (104) peaks. In the voltage range of 3.0-4.3 V, the initial charge/discharge capacities and the rate capability of the cathode active materials are aggravated when Li exists in the precursors. Therefore, it could be concluded that the strict control of Li in a solution for co-precipitation of precursors is necessary in the resynthesis of cathode active materials from spent LIBs.

  9. Phase constitution and interface structure of nano-sized Ag-Cu/AlN multilayers: Experiment and ab initio modeling

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pigozzi, Giancarlo; Janczak-Rusch, Jolanta; Passerone, Daniele

    2012-10-29

    Nano-sized Ag-Cu{sub 8nm}/AlN{sub 10nm} multilayers were deposited by reactive DC sputtering on {alpha}-Al{sub 2}O{sub 3}(0001) substrates. Investigation of the phase constitution and interface structure of the multilayers evidences a phase separation of the alloy sublayers into nanosized grains of Ag and Cu. The interfaces between the Ag grains and the quasi-single-crystalline AlN sublayers are semi-coherent, whereas the corresponding Cu/AlN interfaces are incoherent. The orientation relationship between Ag and AlN is constant throughout the entire multilayer stack. These observations are consistent with atomistic models of the interfaces as obtained by ab initio calculations.

  10. Conformal dynamics of precursors to fracture

    NASA Astrophysics Data System (ADS)

    Barra, F.; Herrera, M.; Procaccia, I.

    2003-09-01

    An exact integro-differential equation for the conformal map from the unit circle to the boundary of an evolving cavity in a stressed 2-dimensional solid is derived. This equation provides an accurate description of the dynamics of precursors to fracture when surface diffusion is important. The solution predicts the creation of sharp grooves that eventually lead to material failure via rapid fracture. Solutions of the new equation are demonstrated for the dynamics of an elliptical cavity and the stability of a circular cavity under biaxial stress, including the effects of surface stress.

  11. Fe–Ni solid solutions in nano-size dimensions: Effect of hydrogen annealing

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kumar, Asheesh, E-mail: asheeshk@barc.gov.in; Meena, S.S.; Banerjee, S.

    Highlights: • Fe–Ni solid solution with nano-size dimensions were prepared and characterized. • Both as prepared and hydrogenated solid solutions have FCC structure of Ni. • Paramagnetic and ferromagnetic domains coexist in these samples. - Abstract: Nanoparticles of Ni{sub 0.50}Fe{sub 0.50} and Ni{sub 0.75}Fe{sub 0.25} alloys were prepared by chemical reduction in ethylene glycol medium. XRD and {sup 57}Fe Mössbauer studies have confirmed the formation of Fe–Ni solid solution in nano-size dimensions with FCC structure. These samples consist of both ferromagnetic and paramagnetic domains which have been attributed to the coexistence of large and small particles as confirmed by atomicmore » force microscopic (AFM) and {sup 57}Fe Mössbauer spectroscopic studies. Improved extent of Fe–Fe exchange interaction existing in Ni{sub 0.50}Fe{sub 0.50} alloy compared to Ni{sub 0.75}Fe{sub 0.25} alloy explains the observed increase in the relative extent of ferromagnetic domains compared to paramagnetic domains in the former sample. Increase in the relative extent of ferromagnetic domains for hydrogenated alloys is due to increase in particle size brought about by the high temperature activation prior to hydrogenation.« less

  12. Modeling & processing of ceramic and polymer precursor ceramic matrix composite materials

    NASA Astrophysics Data System (ADS)

    Wang, Xiaolin

    Synthesis and processing of novel materials with various advanced approaches have attracted much attention of engineers and scientists for the past thirty years. Many advanced materials display a number of exceptional properties and can be produced with different novel processing techniques. For example, AlN is a promising candidate for electronic, optical and opto-electronic applications due to its high thermal conductivity, high electrical resistivity, high acoustic wave velocity and large band gap. Large bulk AlN crystal can be produced by sublimation of AlN powder. Novel nonostructured multicomponent refractory metal-based ceramics (carbides, borides and nitrides) show a lot of exceptional mechanical, thermal and chemical properties, and can be easily produced by pyrolysis of suitable preceramic precursors mixed with metal particles. The objective of this work is to study sublimation and synthesis of AlN powder, and synthesis of SiC-based metal ceramics. For AlN sublimation crystal growth, we will focus on modeling the processes in the powder source that affect significantly the sublimation growth as a whole. To understand the powder porosity evolution and vapor transport during powder sublimation, the interplay between vapor transport and powder sublimation will be studied. A physics-based computational model will be developed considering powder sublimation and porosity evolution. Based on the proposed model, the effect of a central hole in the powder on the sublimation rate is studied and the result is compared to the case of powder without a hole. The effect of hole size on the sublimation rate will be studied. The effects of initial porosity, particle size and driving force on the sublimation rate are also studied. Moreover, the optimal growth condition for large diameter crystal quality and high growth rate will be determined. For synthesis of SiC-based metal ceramics, we will focus on developing a multi-scale process model to describe the dynamic behavior

  13. Chances and limitations of nanosized titanium dioxide practical application in view of its physicochemical properties

    NASA Astrophysics Data System (ADS)

    Bogdan, Janusz; Jackowska-Tracz, Agnieszka; Zarzyńska, Joanna; Pławińska-Czarnak, Joanna

    2015-02-01

    Nanotechnology is a field of science that is nowadays developing in a dynamic way. It seems to offer almost endless opportunities of contribution to many areas of economy and human activity, in general. Thanks to nanotechnology, the so-called nanomaterials can be designed. They present structurally altered materials, with their physical, chemical and biological properties entirely differing from properties of the same materials manufactured in microtechnology. Nanotechnology creates a unique opportunity to modify the matter at the level of atoms and particles. Therefore, it has become possible to obtain items displaying new, useful properties, i.e. self-disinfecting and self-cleaning surfaces. Those surfaces are usually covered by a thin layer of a photocatalyst. The role of the photocatalyst is most of the time performed by the nanosized titanium dioxide (nano-TiO2). Excitation of nano-TiO2 by ultraviolet radiation initiates advanced oxidation processes and reactions leading to the creation of oxygen vacancies that bind water particles. As a result, photocatalytic surfaces are given new properties. Those properties can then be applied in a variety of disciplines, such as medicine, food hygiene, environmental protection or building industry. Practically, the applications include inactivation of microorganisms, degradation of toxins, removing pollutants from buildings and manufacturing of fog-free windows or mirrors.

  14. Synthesis, characterization, properties, and applications of nanosized ferroelectric, ferromagnetic, or multiferroic materials

    DOE PAGES

    Dhak, Debasis; Hong, Seungbum; Das, Soma; ...

    2015-01-01

    Recently, there has been an enormous increase in research activity in the field of ferroelectrics and ferromagnetics especially in multiferroic materials which possess both ferroelectric and ferromagnetic properties simultaneously. However, the ferroelectric, ferromagnetic, and multiferroic properties should be further improved from the utilitarian and commercial viewpoints. Nanostructural materials are central to the evolution of future electronics and information technologies. Ferroelectrics and ferromagnetics have already been established as a dominant branch in electronics sector because of their diverse applications. The ongoing dimensional downscaling of materials to allow packing of increased numbers of components into integrated circuits provides the momentum for evolutionmore » of nanostructural devices. Nanoscaling of the above materials can result in a modification of their functionality. Furthermore, nanoscaling can be used to form high density arrays of nanodomain nanostructures, which is desirable for miniaturization of devices.« less

  15. Structural Evolution of Iron Antimonides from Amorphous Precursors to Crystalline Products Studied by Total Scattering Techniques.

    PubMed

    Bauers, Sage R; Wood, Suzannah R; Jensen, Kirsten M Ø; Blichfeld, Anders B; Iversen, Bo B; Billinge, Simon J L; Johnson, David C

    2015-08-05

    Homogeneous reaction precursors may be used to form several solid-state compounds inaccessible by traditional synthetic routes, but there has been little development of techniques that allow for a priori prediction of what may crystallize in a given material system. Here, the local structures of FeSbx designed precursors are determined and compared with the structural motifs of their crystalline products. X-ray total scattering and atomic pair distribution function (PDF) analysis are used to show that precursors that first nucleate a metastable FeSb3 compound share similar local structure to the product. Interestingly, precursors that directly crystallize to thermodynamically stable FeSb2 products also contain local structural motifs of the metastable phase, despite their compositional disagreement. While both crystalline phases consist of distorted FeSb6 octahedra with Sb shared between either two or three octahedra as required for stoichiometry, a corner-sharing arrangement indicative of AX3-type structures is the only motif apparent in the PDF of either precursor. Prior speculation was that local composition controlled which compounds nucleate from amorphous intermediates, with different compositions favoring different local arrangements and hence different products. This data suggests that local environments in these amorphous intermediates may not be very sensitive to overall composition. This can provide insight into potential metastable phases which may form in a material system, even with a precursor that does not crystallize to the kinetically stabilized product. Determination of local structure in homogeneous amorphous reaction intermediates from techniques such as PDF can be a valuable asset in the development of systematic methods to prepare targeted solid-state compounds from designed precursors.

  16. Nano-sized Superlattice Clusters Created by Oxygen Ordering in Mechanically Alloyed Fe Alloys

    NASA Astrophysics Data System (ADS)

    Hu, Yong-Jie; Li, Jing; Darling, Kristopher A.; Wang, William Y.; Vanleeuwen, Brian K.; Liu, Xuan L.; Kecskes, Laszlo J.; Dickey, Elizabeth C.; Liu, Zi-Kui

    2015-07-01

    Creating and maintaining precipitates coherent with the host matrix, under service conditions is one of the most effective approaches for successful development of alloys for high temperature applications; prominent examples include Ni- and Co-based superalloys and Al alloys. While ferritic alloys are among the most important structural engineering alloys in our society, no reliable coherent precipitates stable at high temperatures have been found for these alloys. Here we report discovery of a new, nano-sized superlattice (NSS) phase in ball-milled Fe alloys, which maintains coherency with the BCC matrix up to at least 913 °C. Different from other precipitates in ferritic alloys, this NSS phase is created by oxygen-ordering in the BCC Fe matrix. It is proposed that this phase has a chemistry of Fe3O and a D03 crystal structure and becomes more stable with the addition of Zr. These nano-sized coherent precipitates effectively double the strength of the BCC matrix above that provided by grain size reduction alone. This discovery provides a new opportunity for developing high-strength ferritic alloys for high temperature applications.

  17. Partial oxidation (“aging”) and surface modification decrease the toxicity of nano-sized zero valent iron.

    EPA Science Inventory

    Nanosize zero-valent iron (nZVI) is used as a redox-active catalyst for in situ remediation of contaminated ground waters. In aqueous environments, nZVI oxidizes over time (i.e., “ages”) to magnetite and other oxides. For remediation, hi...

  18. Degradation of Highly Alloyed Metal Halide Perovskite Precursor Inks: Mechanism and Storage Solutions

    DOE PAGES

    Dou, Benjia; Wheeler, Lance M.; Christians, Jeffrey A.; ...

    2018-03-14

    Whereas the promise of metal halide perovskite (MHP) photovoltaics (PV) is that they can combine high efficiency with solution-processability, the chemistry occurring in precursor inks is largely unexplored. Herein, we investigate the degradation of MHP solutions based on the most widely used solvents, dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). For the MHP inks studied, which contain formamidinium (FA+), methylammonium (MA+), cesium (Cs+), lead (Pb2+), bromide (Br-), and iodide (I-), dramatic compositional changes are observed following storage of the inks in nitrogen in the dark. We show that hydrolysis of DMF in the precursor solution forms dimethylammonium formate, which subsequently incorporatesmore » into the MHP film to compromise the ability of Cs+ and MA+ to stabilize FA+-based MHP. The changes in solution chemistry lead to a modification of the perovskite film stoichiometry, band gap, and structure. The solid precursor salts are stable when ball-milled into a powder, allowing for the storage of large quantities of stoichiometric precursor materials.« less

  19. Degradation of Highly Alloyed Metal Halide Perovskite Precursor Inks: Mechanism and Storage Solutions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dou, Benjia; Wheeler, Lance M.; Christians, Jeffrey A.

    Whereas the promise of metal halide perovskite (MHP) photovoltaics (PV) is that they can combine high efficiency with solution-processability, the chemistry occurring in precursor inks is largely unexplored. Herein, we investigate the degradation of MHP solutions based on the most widely used solvents, dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). For the MHP inks studied, which contain formamidinium (FA+), methylammonium (MA+), cesium (Cs+), lead (Pb2+), bromide (Br-), and iodide (I-), dramatic compositional changes are observed following storage of the inks in nitrogen in the dark. We show that hydrolysis of DMF in the precursor solution forms dimethylammonium formate, which subsequently incorporatesmore » into the MHP film to compromise the ability of Cs+ and MA+ to stabilize FA+-based MHP. The changes in solution chemistry lead to a modification of the perovskite film stoichiometry, band gap, and structure. The solid precursor salts are stable when ball-milled into a powder, allowing for the storage of large quantities of stoichiometric precursor materials.« less

  20. Nanocrystalline Precursors for the Co-Assembly of Crack-Free Metal Oxide Inverse Opals.

    PubMed

    Phillips, Katherine R; Shirman, Tanya; Shirman, Elijah; Shneidman, Anna V; Kay, Theresa M; Aizenberg, Joanna

    2018-05-01

    Inorganic microstructured materials are ubiquitous in nature. However, their formation in artificial self-assembly systems is challenging as it involves a complex interplay of competing forces during and after assembly. For example, colloidal assembly requires fine-tuning of factors such as the size and surface charge of the particles and electrolyte strength of the solvent to enable successful self-assembly and minimize crack formation. Co-assembly of templating colloidal particles together with a sol-gel matrix precursor material helps to release stresses that accumulate during drying and solidification, as previously shown for the formation of high-quality inverse opal (IO) films out of amorphous silica. Expanding this methodology to crystalline materials would result in microscale architectures with enhanced photonic, electronic, and catalytic properties. This work describes tailoring the crystallinity of metal oxide precursors that enable the formation of highly ordered, large-area (mm 2 ) crack-free titania, zirconia, and alumina IO films. The same bioinspired approach can be applied to other crystalline materials as well as structures beyond IOs. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. High resolution photolithography using arrays of polystyrene and SiO2 micro- and nano-sized spherical lenses

    NASA Astrophysics Data System (ADS)

    Dvoretckaia, L. N.; Mozharov, A. M.; Mukhin, I. S.

    2017-11-01

    Photolithography mask made of close-packed array of micro- and nano-sized spherical lenses allows to obtain the ordered structures and provides highest “optical resolution/cost” ratio between all existing photolithography and laser direct writing methods. In this letter, we present results of modeling the propagation of a plane wave falling on the array of quartz (SiO2) microspherical lenses and focusing in the image reverse photoresist layer. We present here experimental results on fabrication of ordered arrays of submicron wells and columns and substrate preparation for growth of monocrystalline nanowires on metal surface using photolithography with mask of SiO2 microspheres. Such ordered nano-sized arrays of wells and columns can be used in fabrication of further growth of monocrystalline nanowires, quantum dots and production of plasmon structures.

  2. [Study on Precursors for Synthesis of Anthraquinone Metabolites from Rheum tanguticum].

    PubMed

    Hasi, Qi-mei-ge; Lj, Hai-ling; Cheng, Yan; Menggen, Qi-qi-ge; Zhang, Yang

    2015-01-01

    To explore the potential precursors of the anthraquinone metabolites from Rheum tanguticum and preliminanly identify the synthesis pathway thereof. Sterile seedlings sprouted from the seeds of Rheum tanguticum were chosen as materials for inducing callus. The effects of different precursors and feeding duration on the callus of Rheum tanguticum and the anthraquinone yield in adult rheum were studied. The greatest improvement of anthraquinone yield was achieved by acetic acid, increasing 43. 9% for the callus and 45. 8% in the adult rheum; the second greatest improvement was achieved by malonic acid, increasing 15. 8% for the callus and only 3. 6% in the adult rheum. The yield of anthraquinone was not influenced significantly by benzoic acid and p-benzoquinone, and in contrast, was inhibited in some degree by shikimic acid and α-ketoglutaric acid. A suitable feeding duration was 36 h, which worked well for the effects of precursors. The precursor for synthesis of anthraquinone metabolites from Rheum tan- guticum is acetic acid, which improves the yields of callus and anthraquinone in adult rheum, concluding that the anthraquinone metabolites are synthesized via polyketone pathway.

  3. Sonocatalytic degradation of some dyestuffs and comparison of catalytic activities of nano-sized TiO2, nano-sized ZnO and composite TiO2/ZnO powders under ultrasonic irradiation.

    PubMed

    Wang, Jun; Jiang, Zhe; Zhang, Liqun; Kang, Pingli; Xie, Yingpeng; Lv, Yanhui; Xu, Rui; Zhang, Xiangdong

    2009-02-01

    Here, a novel sonocatalyst, composite TiO2/ZnO powder, was prepared through the combination of nano-sized TiO2 and ZnO powders. Because of the appropriate adsorbability to organic pollutants and special crystal interphase between TiO2 and ZnO particles, the composite TiO2/ZnO powder exhibits a high sonocatalytic activity under ultrasonic irradiation during the degradation of acid red B. Especially, the sonocatalytic activity of composite TiO2/ZnO powder with 4:1 molar proportion treated at 500 degrees C for 50 min showed obvious improvement compared with pure nano-sized TiO2 and ZnO powders. When the experimental conditions such as 10mg/L acid red B concentration, 1.0 g/L catalyst addition amount, pH=7.0, 20 degrees C system temperature, 100 min ultrasonic time and 50 mL total volume were adopted, the satisfactory degradation ratio and rate were obtained. All experiments indicate that the sonocatalytic method using composite TiO2/ZnO powder may be a more advisable choice for the treatments of non- or low-transparent organic wastewaters in future.

  4. Methods for producing monodispersed particles of barium titanate

    DOEpatents

    Hu, Zhong-Cheng

    2001-01-01

    The present invention is a low-temperature controlled method for producing high-quality, ultrafine monodispersed nanocrystalline microsphere powders of barium titanate and other pure or composite oxide materials having particles ranging from nanosized to micronsized particles. The method of the subject invention comprises a two-stage process. The first stage produces high quality monodispersed hydrous titania microsphere particles prepared by homogeneous precipitation via dielectric tuning in alcohol-water mixed solutions of inorganic salts. Titanium tetrachloride is used as an inorganic salt precursor material. The second stage converts the pure hydrous titania microsphere particles into crystalline barium titanate microsphere powders via low-temperature, hydrothermal reactions.

  5. Y2O3-MgO Nano-Composite Synthesized by Plasma Spraying and Thermal Decomposition of Solution Precursors

    NASA Astrophysics Data System (ADS)

    Muoto, Chigozie Kenechukwu

    This research aims to identify the key feedstock characteristics and processing conditions to produce Y2O3-MgO composite coatings with high density and hardness using solution precursor plasma spray (SPPS) and suspension plasma spray (SPS) processes, and also, to explore the phenomena involved in the production of homogenized nano-composite powders of this material system by thermal decomposition of solution precursor mixtures. The material system would find potential application in the fabrication of components for optical applications such as transparent windows. It was shown that a lack of major endothermic events during precursor decomposition and the resultant formation of highly dense particles upon pyrolysis are critical precursor characteristics for the deposition of dense and hard Y2O3-MgO coatings by SPPS. Using these principles, a new Y2O3-MgO precursor solution was developed, which yielded a coating with Vickers hardness of 560 Hv. This was a considerable improvement over the hardness of the coatings obtained using conventional solution precursors, which was as low as 110 Hv. In the thermal decomposition synthesis process, binary solution precursor mixtures of: yttrium nitrate (Y[n]) or yttrium acetate (Y[a]), with magnesium nitrate (Mg[n]) or magnesium acetate (Mg[a]) were used in order to study the effects of precursor chemistry on the structural characteristics of the resultant Y2O3-MgO powders. The phase domains were coarse and distributed rather inhomogeneously in the materials obtained from the Y[n]Mg[n] and Y[a]Mg[a] mixtures; finer and more homogeneously-distributed phase domains were obtained for ceramics produced from the Y[a]Mg[n] and Y[n]Mg[a] mixtures. It was established that these phenomena were related to the thermal characteristics for the decomposition of the precursors and their effect on phase separation during oxide crystallization. Addition of ammonium acetate to the Y[n[Mg[n] mixture changed the endothermic process to exothermic

  6. Nano-Se attenuates cyclophosphamide-induced pulmonary injury through modulation of oxidative stress and DNA damage in Swiss albino mice.

    PubMed

    Bhattacharjee, Arin; Basu, Abhishek; Biswas, Jaydip; Bhattacharya, Sudin

    2015-07-01

    Chemotherapy is an integral part of modern day treatment regimen but anticancer drugs fail to demarcate between cancerous and normal cells thereby causing severe form of systemic toxicity. Among which pulmonary toxicity is a dreadful complication developed in cancer patients upon cyclophosphamide (CP) therapy. Oxidative stress, fibrosis, and apoptosis are the major patho-mechanisms involved in CP-induced pulmonary toxicity. In the present study, we have synthesized Nano-Se, nanotechnology-based new form of elemental selenium which has significantly lower toxicity and acceptable bioavailability. In order to meet the need of effective drugs against CP-induced adverse effects, nano selenium (Nano-Se) was tested for its possible protective efficacy on CP-induced pulmonary toxicity and bone marrow toxicity. CP intoxication resulted in structural and functional lung impairment which was revealed by massive histopathological changes. Lung injury was associated with oxidative stress/lipid peroxidation as evident by increased in reactive oxygen species, nitric oxide level, and malondialdehyde (MDA) formation with decreased in level of antioxidants such as reduced glutathione, glutathione-S-transferase, glutathione peroxidase, superoxide dismutase, and catalase. Furthermore, CP at a dose of 25 mg/kg b.w. increased pulmonary DNA damage ('comet tail') and triggered DNA fragmentation and apoptosis in mouse bone marrow cells. On the other hand, Nano-Se at a dose of 2 mg Se/kg b.w., significantly inhibited CP-induced DNA damage in bronchoalveolar lavage cells, and decreased the apoptosis and percentage of DNA fragmentation in bone marrow cells and also antagonized the reduction of the activities of antioxidant enzymes and the increase level of MDA. Thus, our results suggest that Nano-Se in pre- and co-administration may serve as a promising preventive strategy against CP-induced pulmonary toxicity.

  7. IR investigation on silicon oxycarbide structure obtained from precursors with 1:1 silicon to carbon atoms ratio and various carbon atoms distribution

    NASA Astrophysics Data System (ADS)

    Niemiec, Wiktor; Szczygieł, Przemysław; Jeleń, Piotr; Handke, Mirosław

    2018-07-01

    Silicon oxycarbide is a material with a number of advantageous properties that strongly depend on its structure. The most common approach to its tailoring is based on varying the silicon to carbon atoms ratio in the preceramic polymeric precursor. This work is the first comparison of the materials obtained from precursors with the same Si to C atoms ratio, but with various distribution of these atoms in the preceramic polymer. In addition to standard mixtures of monomers containing single silicon atom, a number of monomers with high molar masses and well defined structure was used. The IR was used to investigate the structure of the precursors and materials obtained after their annealing in 800 °C. The results show, that not only the distribution of carbon containing groups among the monomers is important, but also the (in)ability of these groups to end up in each other vicinity in the precursor as well as the degree of condensation of each structural unit.

  8. A mobile precursor determines protein resistance on nanostructured surfaces.

    PubMed

    Wang, Kang; Chen, Ye; Gong, Xiangjun; Xia, Jianlong; Zhao, Junpeng; Shen, Lei

    2018-05-09

    Biomaterials are often engineered with nanostructured surfaces to control interactions with proteins and thus regulate their biofunctions. However, the mechanism of how nanostructured surfaces resist or attract proteins together with the underlying design rules remains poorly understood at a molecular level, greatly limiting attempts to develop high-performance biomaterials and devices through the rational design of nanostructures. Here, we study the dynamics of nonspecific protein adsorption on block copolymer nanostructures of varying adhesive domain areas in a resistant matrix. Using surface plasmon resonance and single molecule tracking techniques, we show that weakly adsorbed proteins with two-dimensional diffusivity are critical precursors to protein resistance on nanostructured surfaces. The adhesive domain areas must be more than tens or hundreds of times those of the protein footprints to slow down the 2D-mobility of the precursor proteins for their irreversible adsorption. This precursor model can be used to quantitatively analyze the kinetics of nonspecific protein adsorption on nanostructured surfaces. Our method is applicable to precisely manipulate protein adsorption and resistance on various nanostructured surfaces, e.g., amphiphilic, low-surface-energy, and charged nanostructures, for the design of protein-compatible materials.

  9. Biomimetic routes to nanoscale-toughened oxide ceramics

    NASA Astrophysics Data System (ADS)

    Deschaume, Olivier

    In this work, a novel anion exchange technique has been developed and optimised in order to prepare extra-pure, hydroxide-free solutions of aluminium polyoxocations (A113 and A130) as well as for the preparation of nanosized, highly monodisperse aluminium hydroxide particles in the particle size range 20-200nm. In order for the evolution and composition of the resulting systems to be monitored, an array of characterisation techniques including 27A1 NMR, dynamic light scattering, po-tentiometry, conductometry and UV-Vis spectroscopy, have been implemented and complemented with successful data treatment strategies. The quantitative data obtained indicates that the static anion exchange method is a soft, environmentally friendly, low-cost, energy-saving and convenient procedure for the preparation of Al- containing model systems. The A1 species obtained can be used for high-precision model studies on A1 speciation, and serve as nanosize precursors to a variety of Al-containing materials. The use of these pure A1 precursors has a clear advantage in materials synthesis arising from an improved understanding and better control of A1 speciation. In a second development of the project, the model systems have been used in a nanotectonic approach to biomimetic materials synthesis, with possible applications to the optimisation of Al-containing materials such as ceramics or composite films. Bearing this aim in mind, the interactions of the prepared aluminium species with the model protein BSA and a bioelastomer, elastin, were monitored and the resulting composite materials characterised. The methodology developed for the synthesis and characterisation of pure A1 species and A1 species/biomolecule systems is a robust base for further studies spanning research fields such as Chemistry, Biology or Environmental sciences, and possess a large potential for application to industrial products and processes.

  10. Meat flavor precursors and factors influencing flavor precursors--A systematic review.

    PubMed

    Khan, Muhammad Issa; Jo, Cheorun; Tariq, Muhammad Rizwan

    2015-12-01

    Flavor is the sensory impression sensed by taste and smell buds and is a leading factor determining the meat quality and purchasing decision of the consumer. Meat flavor is characteristic of volatiles produced as a result of reactions of non-volatile components that are induced thermally. The water soluble compounds having low molecular weight and meat lipids are important precursors of cooked meat flavor. The Maillard reaction, lipid oxidation, and vitamin degradation are leading reactions during cooking which develop meat flavor from uncooked meat with little aroma and bloody taste. The pre-slaughter and postmortem factors like animal breed, sex, age, feed, aging and cooking conditions contribute to flavor development of cooked meat. The objective of this review is to highlight the flavor chemistry, meat flavor precursors and factors affecting meat flavor precursors. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. The use of nano-sized eggshell powder for calcium fortification of cow?s and buffalo?s milk yogurts.

    PubMed

    El-Shibiny, Safinaze; El-Gawad, Mona Abd El-Kader Mohamed Abd; Assem, Fayza Mohamed; El-Sayed, Samah Mosbah

    2018-01-01

    Calcium is an essential element for the growth, activity, and maintenance of the human body. Eggshells are a waste product which has received growing interest as a cheap and effective source of dietary calcium. Yogurt is a food which can be fortified with functional additives, including calcium. The aim of this study was to produce yogurt with a high calcium content by fortification with nano-sized eggshell powder (nano-ESP). Nano-sized ESP was prepared from pre-boiled and dried eggshell, using a ball mill. Yogurt was prepared from cow’s milk supplemented with 3% skimmed milk powder, and from buffalo’s milk fortified with 0.1, 0.2 and 0.3% and 0.1, 0.3 and 0.5% nano-ESP respectively. Electron microscopic transmission showed that the powder consisted of nano-sized crystalline struc- tures (~10 nm). Laser scattering showed that particles followed a normal distribution pattern with z-average of 590.5 nm, and had negative zeta-potential of –9.33 ±4.2 mV. Results regarding changes in yogurt composi- tion, acid development, calcium distribution, biochemical changes, textural parameters and sensory attributes have been presented and discussed. The addition of up to 0.3% nano-ESP made cow and buffalo high-calcium yogurts with an acceptable composition and quality. High-calcium yogurt may offer better health benefits, such as combating osteoporosis.

  12. The construction and partial characterization of plasmids containing complementary DNA sequences to human calcitonin precursor polyprotein.

    PubMed Central

    Allison, J; Hall, L; MacIntyre, I; Craig, R K

    1981-01-01

    (1) Total poly(A)-containing RNA isolated from human thyroid medullary carcinoma tissue was shown to direct the synthesis in the wheat germ cell-free system of a major (Mr 21000) and several minor forms of human calcitonin precursor polyproteins. Evidence for processing of these precursor(s) by the wheat germ cell-free system is also presented. (2) A small complementary DNA (cDNA) plasmid library has been constructed in the PstI site of the plasmid pAT153, using total human thyroid medullary carcinoma poly(A)-containing RNA as the starting material. (3) Plasmids containing abundant cDNA sequences were selected by hybridization in situ, and two of these (ph T-B3 and phT-B6) were characterized by hybridization--translation and restriction analysis. Each was shown to contain human calcitonin precursor polyprotein cDNA sequences. (4) RNA blotting techniques demonstrate that the human calcitonin precursor polyprotein is encoded within a mRNA containing 1000 bases. (5) The results demonstrate that human calcitonin is synthesized as a precursor polyprotein. Images Fig. 1. Fig. 2. Fig. 3. PMID:6896146

  13. Structure-related frustrated magnetism of nanosized polyoxometalates: aesthetics and properties in harmony.

    PubMed

    Kögerler, Paul; Tsukerblat, Boris; Müller, Achim

    2010-01-07

    The structural versatility characterizing polyoxometalate chemistry, in combination with the option to deliberately use well-defined building blocks, serves as the foundation for the generation of a large family of magnetic clusters, frequently comprising highly symmetric spin arrays. If the spin centers are coupled by antiferromagnetic exchange, some of these systems exhibit spin frustration, which can result in novel magnetic properties of purely molecular origins. We discuss here the magnetic properties of selected nanosized polyoxometalate clusters featuring spin triangles as their magnetic 'building blocks' or fragments. This includes unique porous Keplerate clusters of the type {(Mo)Mo(5)}(12)M(30) (M = Fe(III), Cr(III), V(IV)) with the spin centers defining a regular icosidodecahedron and the {V(15)As(6)}-type cluster sphere containing a single equilateral spin triangle; these species are widely discussed and studied in the literature for their role in materials science as molecular representations of Kagomé lattices and in relation to quantum computing, respectively. Exhibiting fascinating and unique structural features, these magnetic molecules allow the study of the implications of frustrated spin ordering. Furthermore, this perspective covers the impact of spin frustration on the degeneracy of the ground state and related problems, namely strong magnetic anisotropy and the interplay of antisymmetric exchange and structural Jahn-Teller effects.

  14. Antarctic new particle formation from continental biogenic precursors

    NASA Astrophysics Data System (ADS)

    Kyrö, E.-M.; Kerminen, V.-M.; Virkkula, A.; Dal Maso, M.; Parshintsev, J.; Ruíz-Jimenez, J.; Forsström, L.; Manninen, H. E.; Riekkola, M.-L.; Heinonen, P.; Kulmala, M.

    2012-12-01

    Over Antarctica, aerosol particles originate almost entirely from marine areas, with minor contribution from long-range transported dust or anthropogenic material. The Antarctic continent itself, unlike all other continental areas, has been thought to be practically free of aerosol sources. Here we present evidence of local aerosol production associated with melt-water ponds in the continental Antarctica. We show that in air masses passing such ponds, new aerosol particles are efficiently formed and these particles grow up to sizes where they may act as cloud condensation nuclei (CCN). The precursor vapours responsible for aerosol formation and growth originate very likely from highly abundant cyanobacteria Nostoc commune (Vaucher) communities of local ponds. This is the first time when freshwater vegetation has been identified as an aerosol precursor source. The influence of the new source on clouds and climate may increase in future Antarctica, and possibly elsewhere undergoing accelerating summer melting of semi-permanent snow cover.

  15. Antarctic new particle formation from continental biogenic precursors

    NASA Astrophysics Data System (ADS)

    Kyrö, E.-M.; Kerminen, V.-M.; Virkkula, A.; Dal Maso, M.; Parshintsev, J.; Ruíz-Jimenez, J.; Forsström, L.; Manninen, H. E.; Riekkola, M.-L.; Heinonen, P.; Kulmala, M.

    2013-04-01

    Over Antarctica, aerosol particles originate almost entirely from marine areas, with minor contribution from long-range transported dust or anthropogenic material. The Antarctic continent itself, unlike all other continental areas, has been thought to be practically free of aerosol sources. Here we present evidence of local aerosol production associated with melt-water ponds in continental Antarctica. We show that in air masses passing such ponds, new aerosol particles are efficiently formed and these particles grow up to sizes where they may act as cloud condensation nuclei (CCN). The precursor vapours responsible for aerosol formation and growth originate very likely from highly abundant cyanobacteria Nostoc commune (Vaucher) communities of local ponds. This is the first time freshwater vegetation has been identified as an aerosol precursor source. The influence of the new source on clouds and climate may increase in future Antarctica, and possibly elsewhere undergoing accelerating summer melting of semi-permanent snow cover.

  16. UHPLC-MS/MS determination of varietal thiol precursors in Sauvignon Blanc grapes.

    PubMed

    Vanzo, Andreja; Janeš, Lucija; Požgan, Franc; Velikonja Bolta, Špela; Sivilotti, Paolo; Lisjak, Klemen

    2017-10-13

    Varietal thiol precursors in grapes are subject to metabolic changes during post-harvest treatments. Metabolic activity should therefore be limited after sampling to understand their biosynthesis in the berry and genetic regulation. In this study, berries were frozen in liquid nitrogen immediately after harvesting, transported in dry ice, stored briefly at -80 °C, cryo-milled and extracted without being thawed in cold methanol in a ratio of 1:4 (w/v). A UHPLC-MS/MS method for quantitative determination of the thiol precursors 3-S-glutathionylhexan-1-ol (G3MH), 3-S-cysteinylhexan-1-ol (Cys3MH), 4-S-glutathionyl-4-methylpentan-2-one (G4MMP) and 4-S-cysteinyl-4-methylpentan-2-one (Cys4MMP), glutathione, oxidized glutathione and L-methionine in grapes was developed. Reference material was provided through synthesis of precursors and their deuterium labelled analogues. The average thiol precursor content in grapes in 2013-15 was in the range 8-16 μg kg -1 for G3MH, 1-6 μg kg -1 for Cys3MH, 1-4 μg kg -1 for Cys4MMP and 0.3 μg kg -1 for G4MMP. In 2013 and 2014, the highest precursor content in mature Sauvignon Blanc grapes from vineyards located in Italy regarded G3MH, followed by Cys3MH, Cys4MMP and G4MMP. In 2015, G3MH was again the most abundant precursor, but followed by Cys4MMP, Cys3MH and G4MMP.

  17. Templating Influence of Molecular Precursors on Pr(OH)3 Nanostructures.

    PubMed

    Hemmer, Eva; Cavelius, Christian; Huch, Volker; Mathur, Sanjay

    2015-07-06

    Four new praseodymium alkoxo and amido compounds ([Pr3(μ3-OtBu)2(μ2-OtBu)3(OtBu)4(HOtBu)2] (1), [Pr{OC(tBu)3}3(THF)] (2), [PrCl{N(SiMe3)2}2(THF)]2 (3), and [PrCl{OC(tBu)3}2(THF)]2 (4)) were synthesized and structurally characterized by single-crystal X-ray diffraction analysis. Application of these compounds in solvothermal synthesis of praseodymium oxide/hydroxide nanostructures showed their templating influence on the morphology and phase composition of the resulting solid-state materials. Differential reactivity of the chosen alkoxide ligands toward water and the different arrangements of metal-oxygen units in the studied precursor compounds strongly influenced the kinetics of hydrolysis and cross-condensation reactions as manifested in the morphological changes and phase composition of the final products. Thermal decomposition studies of 1-4 confirmed their conversion into the corresponding oxide phases. Activation of compounds 1, 2, and 4 by either a base or a stoichiometric amount of water showed the distinct influence of their chemical configuration on the obtained nanopowders: whereas 1 solely produced nanorods of Pr(OH)3, 2 predominantly formed a mixture of rod-shaped and spherical particles. The solvothermal decomposition of 4 resulted in Pr(OH)2Cl or PrOCl due to the presence of Cl ligands in the molecular precursor. The resultant materials were thoroughly characterized to demonstrate the relationship between precursor chemistry and the processing parameters that are clearly manifested in the morphology and phase of the final ceramics.

  18. Polyimide Precursor Solid Residuum

    NASA Technical Reports Server (NTRS)

    Weiser, Erik S. (Inventor); St.Clair, Terry L. (Inventor); Echigo, Yoshiaki (Inventor); Kaneshiro, Hisayasu (Inventor)

    2001-01-01

    A polyimide precursor solid residuum is an admixture of an aromatic dianhydride or derivative thereof and an aromatic diamine or derivative thereof plus a complexing agent, which is complexed with the admixture by hydrogen bonding. The polyimide precursor solid residuum is effectively employed in the preparation of polyimide foam and the fabrication of polyimide foam structures.

  19. Nanosized TiO[subscript 2] for Photocatalytic Water Splitting Studied by Oxygen Sensor and Data Logger

    ERIC Educational Resources Information Center

    Zhang, Ruinan; Liu, Song; Yuan, Hongyan; Xiao, Dan; Choi, Martin M. F.

    2012-01-01

    Photocatalytic water splitting by semiconductor photocatalysts has attracted considerable attention in the past few decades. In this experiment, nanosized titanium dioxide (nano-TiO[subscript 2]) particles are used to photocatalytically split water, which is then monitored by an oxygen sensor. Sacrificial reagents such as organics (EDTA) and metal…

  20. Biological synthesis of nanosized sulfide semiconductors: current status and future prospects.

    PubMed

    da Costa, João Pinto; Girão, Ana Violeta; Trindade, Tito; Costa, Maria Clara; Duarte, Armando; Rocha-Santos, Teresa

    2016-10-01

    There have been extensive and comprehensive reviews in the field of metal sulfide precipitation in the context of environmental remediation. However, these works have focused mainly on the removal of metals from aqueous solutions-usually, metal-contaminated effluents-with less emphasis on the precipitation process and on the end-products, frequently centering on metal removal efficiencies. Recently, there has been an increasing interest not only in the possible beneficial effects of these bioremediation strategies for metal-rich effluents but also on the formed precipitates. These metal sulfide materials are of special relevance in industry, due to their optical, electronic, and mechanical properties. Hence, identifying new routes for synthesizing these materials, as well as developing methodologies allowing for the control of the shape and size of particulates, is of environmental, economic, and practical importance. Multiple studies have shown proof-of-concept for the biological synthesis of inorganic metallic sulfide nanoparticles (NPs), resorting to varied organisms or cell components, though this information has scarcely been structured and compiled in a systematic manner. In this review, we overview the biological synthesis methodologies of nanosized metal sulfides and the advantages of these strategies when compared to more conventional chemical routes. Furthermore, we highlight the possibility of the use of numerous organisms for the synthesis of different metal sulfide NPs, with emphasis on sulfate-reducing bacteria (SRB). Finally, we put in perspective the potential of these methodologies in the emerging research areas of biohydrometallurgy and nanobiotechnology for the uptake of metals in the form of metal sulfide nanoparticles. A more complete understanding of the principles underlying the (bio)chemistry of formation of solids in these conditions may lead to the large-scale production of such metal sulfides, while simultaneously allowing an enhanced

  1. NANOSIZED MAGNESIUM OXIDE AS CATALYST FOR THE RAPID AND GREEN SYNTHESIS OF SUBSTITUTED 2-AMINO-2-CHROMENES

    EPA Science Inventory

    A nanosized magnesium oxide catalyzed three-component condensation reaction of aldehyde, malononitrile and ¿-naphthol proceeded rapidly in water/PEG to afford corresponding 2-amino-2-chromenes in high yields at room temperature. The greener protocol was found to be fairly general...

  2. DNA-nanoparticle assemblies go organic: Macroscopic polymeric materials with nanosized features

    PubMed Central

    2012-01-01

    Background One of the goals in the field of structural DNA nanotechnology is the use of DNA to build up 2- and 3-D nanostructures. The research in this field is motivated by the remarkable structural features of DNA as well as by its unique and reversible recognition properties. Nucleic acids can be used alone as the skeleton of a broad range of periodic nanopatterns and nanoobjects and in addition, DNA can serve as a linker or template to form DNA-hybrid structures with other materials. This approach can be used for the development of new detection strategies as well as nanoelectronic structures and devices. Method Here we present a new method for the generation of unprecedented all-organic conjugated-polymer nanoparticle networks guided by DNA, based on a hierarchical self-assembly process. First, microphase separation of amphiphilic block copolymers induced the formation of spherical nanoobjects. As a second ordering concept, DNA base pairing has been employed for the controlled spatial definition of the conjugated-polymer particles within the bulk material. These networks offer the flexibility and the diversity of soft polymeric materials. Thus, simple chemical methodologies could be applied in order to tune the network's electrical, optical and mechanical properties. Results and conclusions One- two- and three-dimensional networks have been successfully formed. Common to all morphologies is the integrity of the micelles consisting of DNA block copolymer (DBC), which creates an all-organic engineered network. PMID:22646980

  3. DNA-nanoparticle assemblies go organic: macroscopic polymeric materials with nanosized features.

    PubMed

    Mentovich, Elad D; Livanov, Konstantin; Prusty, Deepak K; Sowwan, Mukules; Richter, Shachar

    2012-05-30

    One of the goals in the field of structural DNA nanotechnology is the use of DNA to build up 2- and 3-D nanostructures. The research in this field is motivated by the remarkable structural features of DNA as well as by its unique and reversible recognition properties. Nucleic acids can be used alone as the skeleton of a broad range of periodic nanopatterns and nanoobjects and in addition, DNA can serve as a linker or template to form DNA-hybrid structures with other materials. This approach can be used for the development of new detection strategies as well as nanoelectronic structures and devices. Here we present a new method for the generation of unprecedented all-organic conjugated-polymer nanoparticle networks guided by DNA, based on a hierarchical self-assembly process. First, microphase separation of amphiphilic block copolymers induced the formation of spherical nanoobjects. As a second ordering concept, DNA base pairing has been employed for the controlled spatial definition of the conjugated-polymer particles within the bulk material. These networks offer the flexibility and the diversity of soft polymeric materials. Thus, simple chemical methodologies could be applied in order to tune the network's electrical, optical and mechanical properties. One- two- and three-dimensional networks have been successfully formed. Common to all morphologies is the integrity of the micelles consisting of DNA block copolymer (DBC), which creates an all-organic engineered network.

  4. Electrodeposition of nano-sized bismuth on copper foil as electrocatalyst for reduction of CO2 to formate

    NASA Astrophysics Data System (ADS)

    Lv, Weixin; Zhou, Jing; Bei, Jingjing; Zhang, Rui; Wang, Lei; Xu, Qi; Wang, Wei

    2017-01-01

    Electrochemical reduction of carbon dioxide (CO2) to formate is energetically inefficient because high overpotential is required for reduction of CO2 to formate on most traditional catalysts. In this paper, a novel nano-sized Bi-based electrocatalyst deposited on a Cu foil has been synthesized, which can be used as a cathode for electrochemical reduction of CO2 to formate with a low overpotential (0.69 V) and a high selectivity (91.3%). The electrocatalyst can show excellent catalytic performance toward reduction of CO2 which can probably be attributed to the nano-sized structure and the surface oxide layer. The energy efficiency for reduction of CO2 to formate can reach to 50% when an IrxSnyRuzO2/Ti electrode is used as anode, it is one of the highest values found in the literatures and very practicable for sustainable fuel synthesis.

  5. Reflection characterization of nano-sized dielectric structure in Morpho butterfly wings

    NASA Astrophysics Data System (ADS)

    Zhu, Dong

    2017-10-01

    Morpho butterflies living in Central and South America are well-known for their structural-colored blue wings. The blue coloring originates from the interaction of light with nano-sized dielectric structures that are equipped on the external surface of scales covering over their wings. The high-accuracy nonstandard finite-difference time domain (NS-FDTD) method is used to investigate the reflection characterization from the nanostructures. In the NS-FDTD calculation, a computational model is built to mimic the actual tree-like multilayered structures wherever possible using the hyperbolic tangent functions. It is generally known that both multilayer interference and diffraction grating phenomena can occur when light enters the nano-sized multilayered structure. To answer the question that which phenomenon is mainly responsible for the blue coloring, the NS-FDTD calculation is performed under various incidence angles at wavelengths from 360 to 500 nm. The calculated results at one incident wavelength under different incidence angles are visualized in a two-dimensional mapping image, where horizontal and vertical axes are incidence and reflection angles, respectively. The images demonstrate a remarkable transition from a ring-like pattern at shorter wavelengths to a retro-reflection pattern at longer wavelengths. To clarify the origin of the pattern transition, the model is separated into several simpler parts and compared their mapping images with the theoretical diffraction calculations. It can be concluded that the blue coloring at longer wavelengths is mainly caused by the cooperation of multilayer interference and retro-reflection while the effect of diffraction grating is predominant at shorter wavelengths.

  6. Total N-nitrosamine Precursor Adsorption with Carbon Nanotubes: Elucidating Controlling Physiochemical Properties and Developing a Size-Resolved Precursor Surrogate

    NASA Astrophysics Data System (ADS)

    Needham, Erin Michelle

    As drinking water sources become increasingly impaired with nutrients and wastewater treatment plant (WWTP) effluent, formation of disinfection byproducts (DBPs)--such as trihalomethanes (THMs), dihaloacetonitriles (DHANs), and N-nitrosamines--during water treatment may also increase. N-nitrosamines may comprise the bulk of the chronic toxicity in treated drinking waters despite forming at low ng/L levels. This research seeks to elucidate physicochemical properties of carbon nanotubes (CNTs) for removal of DBP precursors, with an emphasis on total N-nitrosamines (TONO). Batch experiments with CNTs were completed to assess adsorption of THM, DHAN, and TONO precursors; physiochemical properties of CNTs were quantified through gas adsorption isotherms and x-ray photoelectron spectroscopy. Numerical modeling was used to elucidate characteristics of CNTs controlling DBP precursor adsorption. Multivariate models developed with unmodified CNTs revealed that surface carboxyl groups and, for TONO precursors, cumulative pore volume (CPV), controlled DBP precursor adsorption. Models developed with modified CNTs revealed that specific surface area controlled adsorption of THM and DHAN precursors while CPV and surface oxygen content were significant for adsorption of TONO precursors. While surrogates of THM and DHAN precursors leverage metrics from UV absorbance and fluorescence spectroscopy, a TONO precursor surrogate has proved elusive. This is important as measurements of TONO formation potential (TONOFP) require large sample volumes and long processing times, which impairs development of treatment processes. TONO precursor surrogates were developed using samples that had undergone oxidative or sorption treatments. Precursors were analyzed with asymmetric flow field-flow fractionation (AF4) with inline fluorescence detection (FLD) and whole water fluorescence excitation-emission matrices (EEMs). TONO precursor surrogates were discovered, capable of predicting changes in

  7. Preparation of TiO2-SiO2 via sol-gel method: Effect of Silica precursor on Catalytic and Photocatalytic properties

    NASA Astrophysics Data System (ADS)

    Fatimah, I.

    2017-02-01

    TiO2-SiO2have been synthesized by the sol-gel method from titanium isopropoxide and varied silica precursors: tetraethyl orthosilicate and tetra methyl ortho silicate. To study the effect of the precursor, prepared materials were characterized by X-ray diffraction, scanning electron microscopy, Diffuse Reflectance UV-vis optical absorption, and also gas sorption analysis. XRD patterns showed the formation of TiO2 anatase in the TiO2-SiO2 composite with different crystallite size from different silica precursor as well as the different surface morphology. The DRUV-vis absorption spectra exhibit similar band gap energy correspond to 3.21eV value while the surface area, pore volume and pore radius of the materials seems to be affected by the precursor. The higher specific surface area contributes to give the enhanced activity in phenol hydroxylation and methylene blue photodegradation.

  8. Effects of ultrasonic vibration on microstructure and mechanical properties of nano-sized SiC particles reinforced Al-5Cu composites.

    PubMed

    Li, Jianyu; Lü, Shulin; Wu, Shusen; Gao, Qi

    2018-04-01

    Ultrasonic vibration (UV) treatment has been successfully applied to improve the particles distribution of nano-sized SiC particles (SiC p ) reinforced Al-5Cu alloy matrix composites which were prepared by combined processes of dry high energy ball milling and squeeze casting. When UV treatment is applied, the distribution of nano-sized SiC p has been greatly improved. After UV for 1 min, large particles aggregates are broken up into small aggregates due to effects of cavitation and the acoustic streaming. After UV for 5 min, all the particles aggregates are dispersed and the particles are uniformly distributed in the composites. Compared with the Al-5Cu matrix alloy, the ultimate tensile strength, yield strength and elongation of the 1 wt% nano-sized SiC p /Al-5Cu composites treated by UV for 5 min are 270 MPa, 173 MPa and 13.3%, which are increased by 7.6%, 6.8% and 29%, respectively. The improvements of mechanical properties after UV are attributed to the uniform distribution of nano particles, grain refinement of aluminum matrix alloy and reduction of porosity in the composites. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Brillouin precursors in Debye media

    NASA Astrophysics Data System (ADS)

    Macke, Bruno; Ségard, Bernard

    2015-05-01

    We theoretically study the formation of Brillouin precursors in Debye media. We point out that the precursors are visible only at propagation distances such that the impulse response of the medium is essentially determined by the frequency dependence of its absorption and is practically Gaussian. By simple convolution, we then obtain explicit analytical expressions of the transmitted waves generated by reference incident waves, distinguishing precursor and main signal by a simple examination of the long-time behavior of the overall signal. These expressions are in good agreement with the signals obtained in numerical or real experiments performed on water in the radio-frequency domain and explain in particular some observed shapes of the precursor. Results are obtained for other remarkable incident waves. In addition, we show quite generally that the shape of the Brillouin precursor appearing alone at sufficiently large propagation distance and the law giving its amplitude as a function of this distance do not depend on the precise form of the incident wave but only on its integral properties. The incidence of a static conductivity of the medium is also examined and explicit analytical results are again given in the limit of weak and strong conductivities.

  10. Study on preparation and microwave absorption property of the core-nanoshell composite materials doped with La.

    PubMed

    Wei, Liqiu; Che, Ruxin; Jiang, Yijun; Yu, Bing

    2013-12-01

    Microwave absorbing material plays a great role in electromagnetic pollution controlling, electromagnetic interference shielding and stealth technology, etc. The core-nanoshell composite materials doped with La were prepared by a solid-state reaction method, which is applied to the electromagnetic wave absorption. The core is magnetic fly-ash hollow cenosphere, and the shell is the nanosized ferrite doped with La. The thermal decomposition process of the sample was investigated by thermogravimetry and differential thermal analysis. The morphology and components of the composite materials were investigated by the X-ray diffraction analysis, the microstructure was observed by scanning electron microscope and transmission electron microscope. The results of vibrating sample magnetometer analysis indicated that the exchange-coupling interaction happens between ferrite of magnetic fly-ash hollow cenosphere and nanosized ferrite coating, which caused outstanding magnetic properties. The microwave absorbing property of the sample was measured by reflectivity far field radar cross section of radar microwave absorbing material with vector network analyzer. The results indicated that the exchange-coupling interaction enhanced magnetic loss of composite materials. Therefore, in the frequency of 5 GHz, the reflection coefficient can achieve -24 dB. It is better than single material and is consistent with requirements of the microwave absorbing material at the low-frequency absorption. Copyright © 2013 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

  11. Method of making nanopatterns and nanostructures and nanopatterned functional oxide materials

    DOEpatents

    Dravid, Vinayak P; Donthu, Suresh K; Pan, Zixiao

    2014-02-11

    Method for nanopatterning of inorganic materials, such as ceramic (e.g. metal oxide) materials, and organic materials, such as polymer materials, on a variety of substrates to form nanopatterns and/or nanostructures with control of dimensions and location, all without the need for etching the materials and without the need for re-alignment between multiple patterning steps in forming nanostructures, such as heterostructures comprising multiple materials. The method involves patterning a resist-coated substrate using electron beam lithography, removing a portion of the resist to provide a patterned resist-coated substrate, and spin coating the patterned resist-coated substrate with a liquid precursor, such as a sol precursor, of the inorganic or organic material. The remaining resist is removed and the spin coated substrate is heated at an elevated temperature to crystallize the deposited precursor material.

  12. Mixed-ligand approach to design of heterometallic single-source precursors with discrete molecular structure.

    PubMed

    Lieberman, Craig M; Navulla, Anantharamulu; Zhang, Haitao; Filatov, Alexander S; Dikarev, Evgeny V

    2014-05-05

    Heterometallic single-source precursors for the Pb/Fe = 1:1 oxide materials, PbFe(β-dik)4 (β-dik = hexafluoroacetylacetonate (hfac, 1), acetylacetonate (acac, 2), and trifluoroacetylacetonate (tfac, 4)), have been isolated by three different solid-state synthetic methods. The crystal structures of heterometallic diketonates 1, 2, and 4 were found to contain polymeric chains built on alternating [Fe(β-dik)2] and [Pb(β-dik)2] units that are held together by bridging M-O interactions. Heterometallic precursors are highly volatile, but soluble only in coordinating solvents, in which they dissociate into solvated homometallic fragments. In order to design the heterometallic precursor with a proper metal/metal ratio and with a discrete molecular structure, we used a combination of two different diketonate ligands. Heteroleptic complex Pb2Fe2(hfac)6(acac)2 (5) has been obtained by optimized stoichiometric reaction of an addition of homo-Fe(acac)2 to heterometallic Pb2Fe(hfac)6 (3) diketonate that can be run in solution on a high scale. The combination of two ligands with electron-withdrawing and electron-donating groups allows changing the connectivity pattern within the heterometallic assembly and yields the precursor with a discrete tetranuclear structure. In accord with its molecular structure, heteroleptic complex 5 is soluble even in noncoordinating solvents and was found to retain its heterometallic structure in solution. Thermal decomposition of heterometallic precursors in air at 750 °C resulted in the target Pb2Fe2O5 oxide, a prospective multiferroic material. Prolonging the annealing time or increasing the decomposition temperature leads to another phase-pure lead-iron oxide PbFe12O19 that is a representative of the important family of magnetic hexaferrites.

  13. Sol-Gel Precursors for Ceramics from Minerals Simulating Soils from the Moon and Mars

    NASA Technical Reports Server (NTRS)

    Sibille, Laurent; Gavira-Gallardo, Jose-Antonio; Hourlier-Bahloul, Djamila

    2003-01-01

    Recent NASA mission plans for the human exploration of our Solar System has set new priorities for research and development of technologies necessary to enable a long-term human presence on the Moon and Mars. The recovery and processing of metals and oxides from mineral sources on other planets is under study to enable use of ceramics, glasses and metals by explorer outposts. We report some preliminary results on the production of sol-gel precursors for ceramic products using mineral resources available in Martian or Lunar soil. The presence of SiO2, TiO2, and A12O3 in both Martian (44 wt.% SiO2, 1 wt.% TiO2, 7 wt.% Al2O3) and Lunar (48 wt.% SiO2, 1.5 wt.% TiO2, 16 wt.% Al2O3) soils and the recent developments in chemical processes to solubilize silicates using organic reagents and relatively little energy indicate that such an endeavor is possible. In order to eliminate the risks involved in the use of hydrofluoric acid to dissolve silicates, two distinct chemical routes are investigated to obtain soluble silicon oxide precursors from Lunar and Martian simulant soils. Clear sol-gel precursors have been obtained by dissolution of silica from Lunar simulant soil in basic ethylene glycol (C2H4(OH)2) solutions to form silicon glycolates. Thermogravimetric Analysis and X-ray Photoelectron Spectroscopy were used to characterize the elemental composition and structure of the precursor molecules. Further concentration and hydrolysis of the products was performed to obtain gel materials for evaluation as ceramic precursors. In the second set of experiments, we used the same starting materials to synthesize silicate esters in acidified alcohol mixtures. Preliminary results indicate the presence of silicon alkoxides in the product of distillation.

  14. Mesoporous metal oxide graphene nanocomposite materials

    DOEpatents

    Liu, Jun; Aksay, Ilhan A.; Kou, Rong; Wang, Donghai

    2016-05-24

    A nanocomposite material formed of graphene and a mesoporous metal oxide having a demonstrated specific capacity of more than 200 F/g with particular utility when employed in supercapacitor applications. A method for making these nanocomposite materials by first forming a mixture of graphene, a surfactant, and a metal oxide precursor, precipitating the metal oxide precursor with the surfactant from the mixture to form a mesoporous metal oxide. The mesoporous metal oxide is then deposited onto a surface of the graphene.

  15. Ultra-thin microporous/hybrid materials

    DOEpatents

    Jiang, Ying-Bing [Albuquerque, NM; Cecchi, Joseph L [Albuquerque, NM; Brinker, C Jeffrey [Albuquerque, NM

    2012-05-29

    Ultra-thin hybrid and/or microporous materials and methods for their fabrication are provided. In one embodiment, the exemplary hybrid membranes can be formed including successive surface activation and reaction steps on a porous support that is patterned or non-patterned. The surface activation can be performed using remote plasma exposure to locally activate the exterior surfaces of porous support. Organic/inorganic hybrid precursors such as organometallic silane precursors can be condensed on the locally activated exterior surfaces, whereby ALD reactions can then take place between the condensed hybrid precursors and a reactant. Various embodiments can also include an intermittent replacement of ALD precursors during the membrane formation so as to enhance the hybrid molecular network of the membranes.

  16. Raman Mapping for the Investigation of Nano-phased Materials

    NASA Astrophysics Data System (ADS)

    Gouadec, G.; Bellot-Gurlet, L.; Baron, D.; Colomban, Ph.

    Nanosized and nanophased materials exhibit special properties. First they offer a good compromise between the high density of chemical bonds by unit volume, needed for good mechanical properties and the homogeneity of amorphous materials that prevents crack initiation. Second, interfaces are in very high concentration and they have a strong influence on many electrical and redox properties. The analysis of nanophased, low crystallinity materials is not straigtforward. The recording of Raman spectra with a geometric resolution close to 0.5 \\upmu {text{ m}^3} and the deep understanding of the Raman signature allow to locate the different nanophases and to predict the properties of the material. Case studies are discussed: advanced polymer fibres, ceramic fibres and composites, textured piezoelectric ceramics and corroded (ancient) steel.

  17. The Effects of Natural Clinoptilolite and Nano-Sized Clinoptilolite Supplementation on Glucose Levels and Oxidative Stress in Rats With Type 1 Diabetes.

    PubMed

    Hossein Nia, Behnoosh; Khorram, Sirous; Rezazadeh, Hassan; Safaiyan, Abdolrasol; Tarighat-Esfanjani, Ali

    2018-02-01

    Oxidative stress has a major role in development of diabetic complications. In this study we investigated whether clinoptilolite and nano-sized clinoptilolite could reduce hyperglycemia and oxidative stress in streptozotocin-induced diabetic rats and attempted to determine which intervention was more effective. Thirty-six rats were randomly allocated to 2 groups; 1 group was randomly chosen as a diabetic group and injected with streptozotocin (60 mg/kg body weight in 0.1 mol/L sodium citrate buffer, pH 4.5) to induce diabetes. Three days after diabetes induction, each group (diabetic group and nondiabetic group) was randomly divided into 3 subgroups of 6 animals each ([1] control, [2] 1% clinoptilolite/food, [3] 1% nano-sized clinoptilolite/food). Supplementation was continued for 28 days. Blood glucose was measured 3 times, at the beginning of the study and on the 14th and 28th days. Activity of antioxidant enzymes, including glutathione peroxidase and superoxide dismutase, and levels of total antioxidant capacity, as well as malondialdehyde, were evaluated. Blood glucose and malondialdehyde were significantly elevated, but there were no statistically significant changes in superoxide dismutase, glutathione peroxidase or total antioxidant capacity in diabetic rats. In diabetic rats treated with nano-sized clinoptilolite, blood glucose decreased to near normal levels (12.4 vs. 27.5 mmol/L). No significant changes were found in the other groups. None of the oxidative stress indices showed significant changes in either the treated or untreated rats. Nano-sized clinoptilolite exerted a hypoglycemic effect in streptozotocin-induced diabetic rats but had no significant influence on oxidative stress markers. Copyright © 2018. Published by Elsevier Inc.

  18. Understanding the Thermal Properties of Precursor-Ionomers to Optimize Fabrication Processes for Ionic Polymer-Metal Composites (IPMCs)

    PubMed Central

    Choi, Kisuk; Olsen, Zakai; Hwang, Taeseon; Nam, Jae-Do

    2018-01-01

    Ionic polymer-metal composites (IPMCs) are one of many smart materials and have ionomer bases with a noble metal plated on the surface. The ionomer is usually Nafion, but recently Aquivion has been shown to be a promising alternative. Ionomers are available in the form of precursor pellets. This is an un-activated form that is able to melt, unlike the activated form. However, there is little study on the thermal characteristics of these precursor ionomers. This lack of knowledge causes issues when trying to fabricate ionomer shapes using methods such as extrusion, hot-pressing, and more recently, injection molding and 3D printing. To understand the two precursor-ionomers, a set of tests were conducted to measure the thermal degradation temperature, viscosity, melting temperature, and glass transition. The results have shown that the precursor Aquivion has a higher melting temperature (240 °C) than precursor Nafion (200 °C) and a larger glass transition range (32–65 °C compared with 21–45 °C). The two have the same thermal degradation temperature (~400 °C). Precursor Aquivion is more viscous than precursor Nafion as temperature increases. Based on the results gathered, it seems that the precursor Aquivion is more stable as temperature increases, facilitating the manufacturing processes. This paper presents the data collected to assist researchers in thermal-based fabrication processes. PMID:29693584

  19. Sol-gel-Derived nano-sized double layer anti-reflection coatings (SiO2/TiO2) for low-cost solar cell fabrication.

    PubMed

    Lee, Seung Jun; Hur, Man Gyu; Yoon, Dae Ho

    2013-11-01

    We investigate nano-sized double layer anti-reflection coatings (ARCs) using a TiO2 and SiO2 sol-gel solution process for mono-crystalline silicon solar cells. The process can be easily adapted for spraying sol-gel coatings to reduce manufacturing cost. The spray-coated SiO2/TiO2 nano-sized double layer ARCs were deposited on mono-crystalline silicon solar cells, and they showed good optical properties. The spray coating process is a lower-cost fabrication process for large-scale coating than vacuum deposition processes such as PECVD. The measured average optical reflectance (300-1200 nm) was about approximately 8% for SiO2/TiO2 nano-sized double layer ARCs. The electrical parameters of a mono-crystalline silicon solar cell and reflection losses show that the SiO2/TiO2 stacks can improve cell efficiency by 0.2% compared to a non-coated mono-crystalline silicon solar cell. In the results, good correlation between theoretical and experimental data was obtained. We expect that the sol-gel spray-coated mono-crystalline silicon solar cells have high potential for low-cost solar cell fabrication.

  20. Nanosized thin SnO₂ layers doped with Te and TeO₂ as room temperature humidity sensors.

    PubMed

    Georgieva, Biliana; Podolesheva, Irena; Spasov, Georgy; Pirov, Jordan

    2014-05-21

    In this paper the humidity sensing properties of layers prepared by a new method for obtaining doped tin oxide are studied. Different techniques-SEM, EDS in SEM, TEM, SAED, AES and electrical measurements-are used for detailed characterization of the thin layers. The as-deposited layers are amorphous with great specific area and low density. They are built up of a fine grained matrix, consisting of Sn- and Te-oxides, and a nanosized dispersed phase of Te, Sn and/or SnTe. The chemical composition of both the matrix and the nanosized particles depends on the ratio R(Sn/Te) and the evaporation conditions. It is shown that as-deposited layers with R(Sn/Te) ranging from 0.4 to 0.9 exhibit excellent characteristics as humidity sensors operating at room temperature-very high sensitivity, good selectivity, fast response and short recovery period. Ageing tests have shown that the layers possess good long-term stability. Results obtained regarding the type of the water adsorption on the layers' surface help better understand the relation between preparation conditions, structure, composition and humidity sensing properties.

  1. Novel polyoxometalate silica nano-sized spheres: efficient catalysts for olefin oxidation and the deep desulfurization process.

    PubMed

    Nogueira, Lucie S; Ribeiro, Susana; Granadeiro, Carlos M; Pereira, Eulália; Feio, Gabriel; Cunha-Silva, Luís; Balula, Salete S

    2014-07-07

    A novel method to prepare silica nano-sized particles incorporating polyoxometalates was developed leading to a new efficient heterogeneous oxidative catalyst. Zinc-substituted polyoxotungstate [PW11Zn(H2O)O39](5-) (PW11Zn) was encapsulated into silica nanoparticles using a cross-linked organic-inorganic core, performed through successive spontaneous reactions in water. The potassium salt of PW11Zn and the composite formed, PW11Zn-APTES@SiO2, were characterized by a myriad of solid-state methods such as FT-IR, FT-Raman, (31)P and (13)C CP/MAS solid-state NMR, elemental analysis and SEM-EDS, confirming the integrity of the PW11Zn structure immobilized in the silica nanoparticles. The new composite has shown to be a versatile catalyst for the oxidation of olefins and also to catalyze the desulfurization of a model oil using H2O2 as the oxidant and acetonitrile as the solvent. The novel composite material was capable of being recycled without significant loss of activity and maintaining its structural stability for consecutive desulfurization and olefin oxidative cycles.

  2. Saturn's Icy satellites: The Role of Sub-Micron Ice Particles and Nano-sized Contaminants (Invited)

    NASA Astrophysics Data System (ADS)

    Clark, R. N.; Cruikshank, D. P.; Dalle Ore, C. M.; Jaumann, R.; Brown, R. H.; Stephan, K.; Buratti, B. J.; Filacchione, G.; Baines, K. H.; Nicholson, P.

    2010-12-01

    The Visual and Infrared Mapping Spectrometer (VIMS) has obtained spatially resolved imaging spectroscopy data on numerous satellites of Saturn. The spectral trends on individual satellites and as compositional gradients within the Saturn system show systematic trends that indicate variable ice grain sizes and contaminants. Compositional mapping shows that the satellite surfaces are composed largely of H2O ice, with small amounts of CO2, trace organics, bound water or OH-bearing minerals, and possible signatures of ammonia, H2O or OH-bearing minerals, and dark, fine-grained materials. The E-ring coats the inner satellites with sub-micron ice particles. The Cassini Rev 49 Iapetus fly-by on September 10, 2007, provided imaging spectroscopy data on both the dark material and the transition zone between the dark material and the visually bright ice on the trailing side. The dark material has very low albedo with a linear increase in reflectance with wavelength, a 3-micron water absorption, and a CO2 absorption. The only reflectance models that can explain the trends include highly absorbing sub-micron materials that create Rayleigh absorption. Radiative transfer models that include diffraction from Rayleigh scattering and Rayleigh absorption are necessary to match observed data. The dark material is well matched by a high component of fine-grained metallic iron plus a small component of nano-phase hematite. Spatially resolved Iapetus data show mixing of dark material with ice and the mixtures display a blue scattering peak and a UV absorption. The blue scattering peak and UV-Visible absorption is observed in spectra of all satellites at some locations where dark material is mixed with the ice. Rayleigh scattering and Rayleigh absorption have also been observed in spectral properties of the Earth's moon. Rayleigh absorption requires high absorption coefficient nano-sized particles, which is also consistent with metallic iron. The UV absorber appears to have increased

  3. Precursor Selection for Property Optimization in Biomorphic SiC Ceramics

    NASA Technical Reports Server (NTRS)

    Varela-Feria, F. M.; Lopez-Robledo, M. J.; Martinez-Fernandez, J.; deArellano-Lopez, A. R.; Singh, M.; Gray, Hugh R. (Technical Monitor)

    2002-01-01

    Biomorphic SiC ceramics have been fabricated using different wood precursors. The evolution of volume, density and microstructure of the woods, carbon performs, and final SiC products are systematically studied in order to establish experimental guidelines that allow materials selection. The wood density is a critical characteristic, which results in a particular final SiC density, and the level of anisotropy in mechanical properties in directions parallel (axial) and perpendicular (radial) to the growth of the wood. The purpose of this work is to explore experimental laws that can help choose a type of wood as precursor for a final SiC product, with a given microstructure, density and level of anisotropy. Preliminary studies of physical properties suggest that not only mechanical properties are strongly anisotropic, but also electrical conductivity and gas permeability, which have great technological importance.

  4. Creep and slip: Seismic precursors to the Nuugaatsiaq landslide (Greenland)

    NASA Astrophysics Data System (ADS)

    Poli, Piero

    2017-09-01

    Precursory signals to material's failure are predicted by numerical models and observed in laboratory experiments or using field data. These precursory signals are a marker of slip acceleration on weak regions, such as crustal faults. Observation of these precursory signals of catastrophic natural events, such as earthquakes and landslides, is necessary for improving our knowledge about the physics of the nucleation process. Furthermore, observing such precursory signals may help to forecast these catastrophic events or reduce their hazard. I report here the observation of seismic precursors to the Nuugaatsiaq landslide in Greenland. Time evolution of the detected precursors implies that an aseismic slip event is taking place for hours before the landslide, with an exponential increase of slip velocity. Furthermore, time evolution of the precursory signals' amplitude sheds light on the evolution of the fault physics during the nucleation process.

  5. Preparation of superconductor precursor powders

    DOEpatents

    Bhattacharya, R.

    1998-08-04

    A process for the preparation of a precursor metallic powder composition for use in the subsequent formation of a superconductor. The process comprises the steps of providing an electrodeposition bath comprising an electrolyte medium and a cathode substrate electrode, and providing to the bath one or more soluble salts of one or more respective metals which are capable of exhibiting superconductor properties upon subsequent appropriate treatment. The bath is continually energized to cause the metallic and/or reduced particles formed at the electrode to drop as a powder from the electrode into the bath, and this powder, which is a precursor powder for superconductor production, is recovered from the bath for subsequent treatment. The process permits direct inclusion of all metals in the preparation of the precursor powder, and yields an amorphous product mixed on an atomic scale to thereby impart inherent high reactivity. Superconductors which can be formed from the precursor powder include pellet and powder-in-tube products. 7 figs.

  6. Preparation of superconductor precursor powders

    DOEpatents

    Bhattacharya, Raghunath; Blaugher, Richard D.

    1995-01-01

    A process for the preparation of a precursor metallic powder composition for use in the subsequent formation of a superconductor. The process comprises the steps of providing an electrodeposition bath comprising an electrolyte medium and a cathode substrate electrode, and providing to the bath one or more soluble salts of one or more respective metals, such as nitrate salts of thallium, barium, calcium, and copper, which are capable of exhibiting superconductor properties upon subsequent appropriate treatment. The bath is continually energized to cause the metallic particles formed at the electrode to drop as a powder from the electrode into the bath, and this powder, which is a precursor powder for superconductor production, is recovered from the bath for subsequent treatment. The process permits direct inclusion of thallium in the preparation of the precursor powder, and yields an amorphous product mixed on an atomic scale to thereby impart inherent high reactivity. Superconductors which can be formed from the precursor powder include pellet and powder-in-tube products.

  7. Preparation of superconductor precursor powders

    DOEpatents

    Bhattacharya, Raghunath

    1998-01-01

    A process for the preparation of a precursor metallic powder composition for use in the subsequent formation of a superconductor. The process comprises the steps of providing an electrodeposition bath comprising an electrolyte medium and a cathode substrate electrode, and providing to the bath one or more soluble salts of one or more respective metals which are capable of exhibiting superconductor properties upon subsequent appropriate treatment. The bath is continually energized to cause the metallic and/or reduced particles formed at the electrode to drop as a powder from the electrode into the bath, and this powder, which is a precursor powder for superconductor production, is recovered from the bath for subsequent treatment. The process permits direct inclusion of all metals in the preparation of the precursor powder, and yields an amorphous product mixed on an atomic scale to thereby impart inherent high reactivity. Superconductors which can be formed from the precursor powder include pellet and powder-in-tube products.

  8. 1994 Accident sequence precursor program results

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Belles, R.J.; Cletcher, J.W.; Copinger, D.A.

    1996-01-01

    The Accident Sequence Precursor (ASP) Program involves the systematic review and evaluation of operational events that have occurred at light-water reactors to identify and categorize precursors to potential severe core damage accident sequences. The results of the ASP Program are published in an annual report. The most recent report, which contains the analyses of the precursors for 1994, is NUREG/CR-4674, Vols. 21 and 22, Precursors to Potential Severe Core Damage Accidents: 1994, A Status Report, published in December 1995. This article provides an overview of the ASP review and evaluation process and a summary of the results for 1994. 12more » refs., 2 figs., 4 tabs.« less

  9. Multilayer Electroactive Polymer Composite Material

    NASA Technical Reports Server (NTRS)

    Harrison, Joycelyn S. (Inventor); Holloway, Nancy M. (Inventor); Park, Cheol (Inventor); Draughon, Gregory K. (Inventor); Ounaies, Zoubeida (Inventor)

    2011-01-01

    An electroactive material comprises multiple layers of electroactive composite with each layer having unique dielectric, electrical and mechanical properties that define an electromechanical operation thereof when affected by an external stimulus. For example, each layer can be (i) a 2-phase composite made from a polymer with polarizable moieties and an effective amount of carbon nanotubes incorporated in the polymer for a predetermined electromechanical operation, or (ii) a 3-phase composite having the elements of the 2-phase composite and further including a third component of micro-sized to nano-sized particles of an electroactive ceramic incorporated in the polymer matrix.

  10. Control of Cr6+ emissions from gas metal arc welding using a silica precursor as a shielding gas additive.

    PubMed

    Topham, Nathan; Wang, Jun; Kalivoda, Mark; Huang, Joyce; Yu, Kuei-Min; Hsu, Yu-Mei; Wu, Chang-Yu; Oh, Sewon; Cho, Kuk; Paulson, Kathleen

    2012-03-01

    Hexavalent chromium (Cr(6+)) emitted from welding poses serious health risks to workers exposed to welding fumes. In this study, tetramethylsilane (TMS) was added to shielding gas to control hazardous air pollutants produced during stainless steel welding. The silica precursor acted as an oxidation inhibitor when it decomposed in the high-temperature welding arc, limiting Cr(6+) formation. Additionally, a film of amorphous SiO(2) was deposited on fume particles to insulate them from oxidation. Experiments were conducted following the American Welding Society (AWS) method for fume generation and sampling in an AWS fume hood. The results showed that total shielding gas flow rate impacted the effectiveness of the TMS process. Increasing shielding gas flow rate led to increased reductions in Cr(6+) concentration when TMS was used. When 4.2% of a 30-lpm shielding gas flow was used as TMS carrier gas, Cr(6+) concentration in gas metal arc welding (GMAW) fumes was reduced to below the 2006 Occupational Safety and Health Administration standard (5 μg m(-3)) and the efficiency was >90%. The process also increased fume particle size from a mode size of 20 nm under baseline conditions to 180-300 nm when TMS was added in all shielding gas flow rates tested. SiO(2) particles formed in the process scavenged nanosized fume particles through intercoagulation. Transmission electron microscopy imagery provided visual evidence of an amorphous film of SiO(2) on some fume particles along with the presence of amorphous SiO(2) agglomerates. These results demonstrate the ability of vapor phase silica precursors to increase welding fume particle size and minimize chromium oxidation, thereby preventing the formation of hexavalent chromium.

  11. Template-assisted mineral formation via an amorphous liquid phase precursor route

    NASA Astrophysics Data System (ADS)

    Amos, Fairland F.

    The search for alternative routes to synthesize inorganic materials has led to the biomimetic route of producing ceramics. In this method, materials are manufactured at ambient temperatures and in aqueous solutions with soluble additives and insoluble matrix, similar to the biological strategy for the formation of minerals by living organisms. Using this approach, an anionic polypeptide additive was used to induce an amorphous liquid-phase precursor to either calcium carbonate or calcium phosphate. This precursor was then templated on either organic or inorganic substrates. Non-equilibrium morphologies, such as two-dimensional calcium carbonate films, one-dimensional calcium carbonate mesostructures and "molten" calcium phosphate spherulites were produced, which are not typical of the traditional (additive-free) solution grown crystals in the laboratory. In the study of calcium carbonate, the amorphous calcium carbonate mineral formed via the liquid-phase precursor, either underwent a dissolution-recrystallization event or a pseudo-solid-state transformation to produce different morphologies and polymorphs of the mineral. Discrete or aggregate calcite crystals were formed via the dissolution of the amorphous phase to allow the reprecipitation of the stable crystal. Non-equilibrium morphologies, e.g., films, mesotubules and mesowires were templated using organic and inorganic substrates and compartments. These structures were generated via an amorphous solid to crystalline solid transformation. Single crystalline tablets and mesowires of aragonite, which are reported to be found only in nature as skeletal structures of marine organisms, such as mollusk nacre and echinoderm teeth, were successfully synthesized. These biomimetic structures were grown via the polymer-induced liquid-phase precursor route in the presence of magnesium. Only low magnesium-bearing calcite was formed in the absence of the polymer. A similar approach of using a polymeric additive was

  12. Flow-induced voltage generation by moving a nano-sized ionic liquids droplet over a graphene sheet: Molecular dynamics simulation.

    PubMed

    Shao, Qunfeng; Jia, Jingjing; Guan, Yongji; He, Xiaodong; Zhang, Xiaoping

    2016-03-28

    In this work, the phenomenon of the voltage generation is explored by using the molecular dynamics simulations, which is performed by driving a nano-sized droplet of room temperature ionic liquids moving along the monolayer graphene sheet for the first time. The studies show that the cations and anions of the droplet will move with velocity nonlinearly increasing to saturation arising by the force balance. The traditional equation for calculating the induced voltage is developed by taking the charge density into consideration, and larger induced voltages in μV-scale are obtained from the nano-size simulation systems based on the ionic liquids (ILs) for its enhanced ionic drifting velocities. It is also derived that the viscosity acts as a reduction for the induced voltage by comparing systems composed of two types of ILs with different viscosity and temperature.

  13. Synthesis of In2O3nanoparticles by thermal decomposition of a citrate gel precursor

    NASA Astrophysics Data System (ADS)

    Rey, J. F. Q.; Plivelic, T. S.; Rocha, R. A.; Tadokoro, S. K.; Torriani, I.; Muccillo, E. N. S.

    2005-06-01

    This paper describes the synthesis of indium oxide by a modified sol-gel method, and the study of thermal decomposition of the metal complex in air. The characterization of the intermediate as well as the final compounds was carried out by thermogravimetry, differential thermal analysis, Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, and small angle X-ray scattering. The results show that the indium complex decomposes to In2O3 with the formation of an intermediate compound. Nanoparticles of cubic In2O3 with crystallite sizes in the nanosize range were formed after calcination at temperatures up to 900°C. Calcined materials are characterized by a polydisperse distribution of spherical particles with sharp and smooth surfaces.

  14. Electrochemical and in vitro behavior of the nanosized composites of Ti-6Al-4V and TiO2 fabricated by friction stir process

    NASA Astrophysics Data System (ADS)

    Zhang, Chengjian; Ding, Zihao; Xie, Lechun; Zhang, Lai-Chang; Wu, Laizhi; Fu, Yuanfei; Wang, Liqiang; Lu, Weijie

    2017-11-01

    Although Ti-6Al-4V has been widely used in biomaterial field. Compared with other classes of materials, it still encounters some problems such as low surface hardness and relative low biocompatibility. To solve these problems friction stir processing (FSP) was applied to fabricate a nanosized composite layer of TiO2 and Ti-6Al-4V. Uniform distribution of TiO2 particles with some clusters on the surface of alloy can be observed. Due to severe plastic deformation and stirring heat, nanocrystallines and amorphous TiO2 can be observed in stir zone. FSPed samples show significant improvement in surface microhardness and biocompatibility due to its modified structure compared with original sample. In addition, through corrosion behaviors of the samples in simulated body fluid, it is found that FSP can enhance whilst TiO2 reduces the possibility and corrosion rate of material in environment of human body.

  15. Hydrothermal growth of ZnO nanowire arrays: fine tuning by precursor supersaturation

    DOE PAGES

    Yan, Danhua; Cen, Jiajie; Zhang, Wenrui; ...

    2016-12-20

    In this paper, we develop a technique that fine tunes the hydrothermal growth of ZnO nanowires to address the difficulties in controlling their growth in a conventional one-pot hydrothermal method. In our technique, precursors are separately and slowly supplied with the assistance of a syringe pump, through the entire course of the growth. Compared to the one-pot method, the significantly lowered supersaturation of precursors helps eliminating competitive homogeneous nucleation and improves the reproducibility. The supersaturation degree can be readily tuned by the precursor quantity and injection rate, thus forming ZnO nanowire arrays of various geometries and packing densities in amore » highly controllable fashion. The precise control of ZnO nanowire growth enables systematic studies on the correlation between the material's properties and its morphology. Finally, in this work, ZnO nanowire arrays of various morphologies are studied as photoelectrochemical (PEC) water splitting photoanodes, in which we establish clear correlations between the water splitting performance and the nanowires' size, shape, and packing density.« less

  16. CVD of SiC and AlN using cyclic organometallic precursors

    NASA Technical Reports Server (NTRS)

    Interrante, L. V.; Larkin, D. J.; Amato, C.

    1992-01-01

    The use of cyclic organometallic molecules as single-source MOCVD precursors is illustrated by means of examples taken from our recent work on AlN and SiC deposition, with particular focus on SiC. Molecules containing (AlN)3 and (SiC)2 rings as the 'core structure' were employed as the source materials for these studies. The organoaluminum amide, (Me2AlNH2)3, was used as the AlN source and has been studied in a molecular beam sampling apparatus in order to determine the gas phase species present in a hot-wall CVD reactor environment. In the case of SiC CVD, a series of disilacyclobutanes (Si(XX')CH2)2 (with X and X' = H, CH3, and CH2SiH2CH3), were examined in a cold-wall, hot-stage CVD reactor in order to compare their relative reactivities and prospective utility as single-source CVD precursors. The parent compound, disilacyclobutane, (SiH2CH2)2, was found to exhibit the lowest deposition temperature (ca. 670 C) and to yield the highest purity SiC films. This precursor gave a highly textured, polycrystalline film on the Si(100) substrates.

  17. The Interrelationships of Mathematical Precursors in Kindergarten

    PubMed Central

    Cirino, Paul T.

    2011-01-01

    This study evaluated the interrelations among cognitive precursors across quantitative, linguistic, and spatial attention domains that have been implicated for math achievement in young children. The dimensionality of the quantity precursors was evaluated in 286 Kindergarteners via latent variable techniques, and the contribution of precursors from each domain was established for small sums addition. Results showed a five factor structure for the quantity precursors with the major distinction between nonsymbolic and symbolic tasks. The overall model demonstrated good fit, and strong predictive power (R2 = 55%) for addition number combinations. Linguistic and spatial attention domains showed indirect relationships with outcomes, with their effects mediated by symbolic quantity measures. These results have implications for the measurement of mathematical precursors, and yield promise for predicting future math performance. PMID:21194711

  18. Particle Size Influence on the Effective Permeability of Composite Materials

    NASA Astrophysics Data System (ADS)

    Xiang, Tai; Zhong, Ru-Neng; Yao, Bin; Qin, Shao-Jing; Zheng, Qin-Hong

    2018-05-01

    The energy method, which estimates the effective permeability of composite material is proposed. We approximate the effective static magnetic permeability by energy method and Maxwell-Garnett method for spherical particles dispersing system. Considering the effect of the interface layer between the medium and the particle, we study the nanoparticles embedded in a medium exactly. The interface layer property plays a significant factor for the effective permeability of the composite material in which nano-sized particles embedded. Supported by National Natural Science Foundation of Yunnan province under Grant No. 2014FB141 and National Natural Science Foundation under Grant No. 1121403 of China

  19. Observation of >400-eV precursor plasmas from low-wire-number copper arrays at the 1-MA zebra facility.

    PubMed

    Coverdale, C A; Safronova, A S; Kantsyrev, V L; Ouart, N D; Esaulov, A A; Deeney, C; Williamson, K M; Osborne, G C; Shrestha, I; Ampleford, D J; Jones, B

    2009-04-17

    Experiments with cylindrical copper wire arrays at the 1-MA Zebra facility show that high temperatures exist in the precursor plasmas formed when ablated wire array material accretes on the axis prior to the stagnation of a z pinch. In these experiments, the precursor radiated approximately 20% of the >1000 eV x-ray output, and time-resolved spectra show substantial emission from Cu L-shell lines. Modeling of the spectra shows an increase in temperature as the precursor forms, up to approximately 450 eV, after which the temperature decreases to approximately 220-320 eV until the main implosion.

  20. Effect of a nano-sized TiC particle addition on the flow-assisted corrosion resistance of SA 106B carbon steel

    NASA Astrophysics Data System (ADS)

    Park, Jin-Ju; Park, Eun-Kwang; Lee, Gyoung-Ja; Rhee, Chang-Kyu; Lee, Min-Ku

    2017-09-01

    Carbon steel with dispersed nano-sized TiC ceramic particles was fabricated by the ex-situ introduction of the particles into the melt, with the flow-assisted corrosion (FAC) resistance then investigated in the presence and absence of TiC nanoparticles using a once-through type of FAC loop test. From the potentiodynamic polarization curves, the current density at any given anodic potential was decreased and the open-circuit potential was increased by the addition of TiC nanoparticles. In addition, when the nano-sized TiC particles were added, the FAC rate was 1.38 times lower than that of carbon steel without TiC nanoparticles, indicating an improvement of the FAC resistance due to the homogeneous distribution of the TiC reinforcing nanoparticles.

  1. [Spectral studies on nano-sized titania photocatalysts prepared by different drying methods].

    PubMed

    Ye, Zhao; Zhang, Han-hui; Pan, Hai-bo; Pan, Hong-qing

    2002-12-01

    Nano-sized TiO2 photocatalysts were prepared by drying the ethanol gel of titanium tetrabutoxide through natural state, supercritical ethanol, supercritical carbon dioxide drying methods and characterized by XRD, FTIR spectroscopy, FT-Raman spectroscopy and fluorescent spectroscopy, respectively. We regard degradation of rhodamine B by photocatalyst as a model reaction, and compare photocatalytic activities of samples obtained. The experimental results show that different drying methods have strong effect on crystal structure, energy band structure, optical adsorption property, surface quality and photocatalytic activity, TiO2 photocatalyst prepared by supercritical carbon dioxide drying method has superior photocatalytic activity.

  2. Directed assembly of nanomaterials for miniaturized sensors by dip-pen nanolithography using precursor inks

    NASA Astrophysics Data System (ADS)

    Su, Ming

    The advent of nanomaterials with enhanced properties and the means to pattern them in a controlled fashion have paved the way to construct miniaturized sensors for improved detection. However it remains a challenge for the traditional methods to create such sensors and sensor arrays. Dip pen nanolithography (DPN) can form nanostructures on a substrate by controlling the transfer of molecule inks. However, previous DPN can not pattern solid materials on insulating surfaces, which are necessary to form functional electronic devices. In the dissertation, the concept of reactive precursor inks for DPN is developed for the generation of solid functional nanostructures of the following materials: organic molecule, sol-gel material, and conducting polymer. First, the covalent bonding is unnecessary for DPN as shown in the colored ink DPN; therefore the numbers of molecules that can be patterned is extended beyond thiol or thiolated molecules. Subsequently, a reactive precursor strategy (sol) is developed to pattern inorganic or organic/inorganic composite nanostructures on silicon based substrates. The method works by hydrolysis of metal precursors in the water meniscus and allows the preparation of solid structures with controlled geometry beyond the individual molecule level. Then the SnO 2 nanostructures patterned between the gaps of electrodes are tested as gas sensors. Proof-of-concept experiments are demonstrated on miniaturized sensors that show fast response and recovery to certain gases. Furthermore, an eight-unit sensor array is fabricated on a chip using SnO2 sols that are doped with different metals. The multiplexed device can recognize different gases by comparing the response patterns with the reference patterns of known gases generated on the same array. At last, the idea of precursor ink for DPN is extended to construct conducting polymer based devices. By using an acid promoted polymerization approach, conducting polymers are patterned on silicon dioxide

  3. Tuning the optical properties of ZnO nanorods by variation of precursor concentration through hydrothermal method

    NASA Astrophysics Data System (ADS)

    Kumari, Lakshmi; Kar, Asit Kumar

    2018-05-01

    ZnO nanorods with varying precursor concentration have been successfully synthesized by the hydrothermal method. The effect of the precursor concentration on the structural, morphological and optical properties of the resulting nanorods was investigated by means of X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), UV-Vis spectroscopy and photoluminescence (PL) spectroscopy. The crystalline structural characterization demonstrated that the synthesized materials crystallize in pure ZnO wurtzite structure without any other secondary phase. SEM micrographs demonstrate nanorod type features in all the samples. In addition, they show that increase of precursor concentration changes the length and diameter of nanorods. The UV-Vis studies show a strong absorption band in UV region at 373 nm attributed to the band-edge absorption of wurtzite hexagonal ZnO, blue shifted relative to its bulk form (380 nm). The PL spectra of obtained nanorods excited at 360 nm present broad visible emission. Moreover, as the visible region (from 510 to 550 nm) is concerned, it is speculated that the increase of the precursor concentration affects strongly the kind of interstitial defects (Oi, Zni and Vo) formed in ZnO nanorods. The luminescence intensity decreases with the increase of precursor concentration.

  4. Photopatternable electrochromic materials from oxetane precursors.

    PubMed

    Leliège, Antoine; Barik, Satyananda; Skene, W G

    2014-05-14

    Conjugated thiophenoazomethine triads containing an acid sensitive oxetane group were prepared. The solution processable monomers were immobilized on glass and ITO coated glass substrates by photoacid induced cationic ring-opening polymerization (CROP) of the oxetane moiety. Photolithography using a photoacid generator and photosensitizer were used to pattern an electroactive polymer. Micro- and macroscale patterns ranging between 20 μm and 50 mm were possible with the electrochromic materials. The photopolymerized azomethine remained electroactive, and it could be repeatedly switched electrochemically between its neutral (mauve, λmax=535 nm) and oxidized (blue, λmax=585 nm) states without degradation. The electrochromic properties were evaluated in a simulated device where the colors were successfully cycled between blue (oxidized) and purple (neutral) states with applied biases of +0.6 V and -0.6 V vs Fc/Fc+ under ambient conditions without significant color fatigue or degradation.

  5. Method for the preparation of thallium-containing superconducting materials by precipitation

    DOEpatents

    Bunker, Bruce C.; Lamppa, Diana L.; Voigt, James A.

    1991-01-01

    This invention provides improved methods for the preparation of precursor powders that are used in the preparation of superconducting ceramic materials that contain thallium. A first solution that contains the hydrogen peroxide and metal cations, other than thallium, that will be part of the ceramic is quickly mixed with a second solution that contains precipitating anions and thallium (I) to form a precipitate which is dried to yield precursor powders. The precursor powders are calcined an sintered to produce superconducting materials that contain thallium.

  6. Vapor-liquid-solid mechanisms: Challenges for nanosized quantum cluster/dot/wire materials

    NASA Astrophysics Data System (ADS)

    Cheyssac, P.; Sacilotti, M.; Patriarche, G.

    2006-08-01

    The growth mechanism model of a nanoscaled material is a critical step that has to be refined for a better understanding of a nanostructure's dot/wire fabrication. To do so, the growth mechanism will be discussed in this paper and the influence of the size of the metallic nanocluster starting point, referred to later as "size effect," will be studied. Among many of the so-called size effects, a tremendous decrease of the melting point of the metallic nanocluster changes the physical properties as well as the physical/mechanical interactions inside the growing structure composed of a metallic dot on top of a column. The thermodynamic size effect is related to the bending or curvature of chains of atoms, giving rise to the weakening of bonds between them; this size or curvature effect is described and approached to crystal nanodot/wire growth. We will describe this effect as that of a "cooking machine" when the number of atoms decreases from ˜1023at./cm3 for a bulk material to a few tens of them in a 1-2nm diameter sphere. The decrease of the number of atoms in a metallic cluster from such an enormous quantity is accompanied by a lowering of the melting temperature that extends from 200 up to 1000K, depending on the metallic material and its size under study. In this respect, the vapor-liquid-solid (VLS) model, which is the most utilized growth mechanism for quantum nanowires and nanodots, is critically exposed to size or curvature effects (CEs). More precisely, interactions in the vicinity of the growth regions should be reexamined. Some results illustrating the growth of micrometer-/nanometer-sized materials are presented in order to corroborate the CE/VLS models utilized by many research groups in today's nanosciences world. Examples of metallic clusters and semiconducting wires will be presented. The results and comments presented in this paper can be seen as a challenge to be overcome. From them, we expect that in a near future an improved model can be exposed

  7. On the difficulties of detecting PP precursors

    NASA Astrophysics Data System (ADS)

    Lessing, Stephan; Thomas, Christine; Saki, Morvarid; Schmerr, Nicholas; Vanacore, Elizabeth

    2015-06-01

    The PP precursors are seismic waves that form from underside reflections of P waves off discontinuities in the upper mantle transition zone (MTZ). These seismic phases are used to map discontinuity topography, sharpness, and impedance contrasts; the resulting structural variations are then often interpreted as evidence for temperature and/or mineralogy variations within the mantle. The PP precursors as well as other seismic phases have been used to establish the global presence of seismic discontinuities at 410 and 660 km depth. Intriguingly, in more than 80 per cent of PP precursor observations the seismic wave amplitudes are significantly weaker than the amplitudes predicted by seismic reference models. Even more perplexing is the observation that 1-5 per cent of all earthquakes (which are 20-25 per cent of earthquakes with clear PP waveforms) do not show any evidence for the PP precursors from the discontinuities even in the presence of well-developed PP waveforms. Non-detections are found in six different data sets consisting of tens to hundreds of events. We use synthetic modelling to examine a suite of factors that could be responsible for the absence of the PP precursors. The take-off angles for PP and the precursors differ by only 1.2-1.5°; thus source-related complexity would affect PP and the precursors. A PP wave attenuated in the upper mantle would increase the relative amplitude of the PP precursors. Attenuation within the transition zone could reduce precursor amplitudes, but this would be a regional phenomenon restricted to particular source receiver geometries. We also find little evidence for deviations from the theoretical travel path of seismic rays expected for scattered arrivals. Factors that have a strong influence include the stacking procedures used in seismic array techniques in the presence of large, interfering phases, the presence of topography on the discontinuities on the order of tens of kilometres, and 3-D lateral heterogeneity in

  8. Using a Z-pinch precursor plasma to produce a cylindrical, hotspot ignition, ICF

    NASA Astrophysics Data System (ADS)

    Chittenden, Jeremy

    2005-10-01

    We show that if the same precursor plasma that exists in metal wire arrays can be generated with a Deuterium-Tritium plasma then this precursor provides an ideal target for a cylindrical magneto-inertial ICF scheme. The precursor is generated from a fraction of the mass of the array which arrives on the axis early in time and remains confined at high density by the inertia of further material bombarding the axis. Later on, the main implosion of the DT Z-pinch produces a dense, low temperature shell which compressively heats the precursor target to high temperatures and tamps its expansion. The azimuthal magnetic field in the hotspot is sufficient to reduce the Larmor radius for the alpha particles to much less than the hotspot size, which dramatically reduces the ρR required for ignition. A computational analysis of this approach is presented, including a study of the thermonuclear burn wave propagation. The robustness of the scheme with respect to instabilities, confinement time and drive parameters is examined. The results indicate that a high energy gain can be achieved using Z-pinches with 50-100 MA currents and a few hundred nanosecond rise-times. This work was partially supported by the U.S. Department of Energy through cooperative agreement DE-FC03-02NA00057.

  9. A novel precursor system and its application to produce tin doped indium oxide.

    PubMed

    Veith, M; Bubel, C; Zimmer, M

    2011-06-14

    A new type of precursor has been developed by molecular design and synthesised to produce tin doped indium oxide (ITO). The precursor consists of a newly developed bimetallic indium tin alkoxide, Me(2)In(O(t)Bu)(3)Sn (Me = CH(3), O(t)Bu = OC(CH(3))(3)), which is in equilibrium with an excess of Me(2)In(O(t)Bu). This quasi single-source precursor is applied in a sol-gel process to produce powders and coatings of ITO using a one-step heat treatment process under an inert atmosphere. The main advantage of this system is the simple heat treatment that leads to the disproportionation of the bivalent Sn(II) precursor into Sn(IV) and metallic tin, resulting in an overall reduced state of the metal in the final tin doped indium oxide (ITO) material, hence avoiding the usually necessary reduction step. Solid state (119)Sn-NMR measurements of powder samples confirm the appearance of Sn(II) in an amorphous gel state and of metallic tin after annealing under nitrogen. The corresponding preparation of ITO coatings by spin coating on glass leads to transparent conductive layers with a high transmittance of visible light and a low electrical resistivity without the necessity of a reduction step.

  10. Remarkable Second-Order Optical Nonlinearity of Nano-Sized Au Cluster: A TDDFT Study

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wu, Kechen; Li, Jun; Lin, Chensheng

    2004-04-21

    The dipole polarizability, static first hyperpolarizability, and UV-vis spectrum of the recently identified nano-sized tetrahedral cluster of Au have been investigated by using time-dependent density functional response theory. We have discovered that the Au cluster possesses remarkably large molecular second-order optical nonlinearity with the first hyperpolarizabilty (xyz) calculated to be 14.3 x 10 electrostatic unit (esu). The analysis of the low-energy absorption band suggests that the charge transfer from the edged gold atoms to the vertex ones plays the key role in nonlinear optical (NLO) response of Au.

  11. Structural and Morphological Evaluation of Nano-Sized MoSi2 Powder Produced by Mechanical Milling

    NASA Astrophysics Data System (ADS)

    Sameezadeh, Mahmood; Farhangi, Hassan; Emamy, Masoud

    Nano-sized intermetallic powders have received great attention owing to their property advantages over conventional micro-sized counterparts. In the present study nano-sized MoSi2 powder has been produced successfully from commercially available MoSi2 (3 μm) by a mechanical milling process carried out for a period of 100 hours. The effects of milling time on size and morphology of the powders were studied by SEM and TEM and image analyzing system. The results indicate that the as-received micrometric powder with a wide size distribution of irregular shaped morphology changes to a narrow size distribution of nearly equiaxed particles with the progress of attrition milling up to 100 h, reaching an average particle size of 71 nm. Structural evolution of milled samples was characterized by XRD to determine the crystallite size and lattice microstrain using Williamson-Hall method. According to the results, the crystallite size of the powders decreases continuously down to 23 nm with increasing milling time up to 100 h and this size refinement is more rapid at the early stages of the milling process. On the other hand, the lattice strain increases considerably with milling up to 65 h and further milling causes no significant changes of lattice strain.

  12. Thin Film CuInS2 Prepared by Spray Pyrolysis with Single-Source Precursors

    NASA Technical Reports Server (NTRS)

    Jin, Michael H.; Banger, Kulinder K.; Harris, Jerry D.; Cowen, Jonathan E.; Hepp, Aloysius F.; Lyons, Valerie (Technical Monitor)

    2002-01-01

    Both horizontal hot-wall and vertical cold-wall atmospheric chemical spray pyrolysis processes deposited near single-phase stoichiometric CuInS2 thin films. Single-source precursors developed for ternary chalcopyrite materials were used for this study, and a new liquid phase single-source precursor was tested with a vertical cold-wall reactor. The depositions were carried out under an argon atmosphere, and the substrate temperature was kept at 400 C. Columnar grain structure was obtained with vapor deposition, and the granular structure was obtained with (liquid) droplet deposition. Conductive films were deposited with planar electrical resistivities ranging from 1 to 30 Omega x cm.

  13. Functional Analyses and Treatment of Precursor Behavior

    PubMed Central

    Najdowski, Adel C; Wallace, Michele D; Ellsworth, Carrie L; MacAleese, Alicia N; Cleveland, Jackie M

    2008-01-01

    Functional analysis has been demonstrated to be an effective method to identify environmental variables that maintain problem behavior. However, there are cases when conducting functional analyses of severe problem behavior may be contraindicated. The current study applied functional analysis procedures to a class of behavior that preceded severe problem behavior (precursor behavior) and evaluated treatments based on the outcomes of the functional analyses of precursor behavior. Responding for all participants was differentiated during the functional analyses, and individualized treatments eliminated precursor behavior. These results suggest that functional analysis of precursor behavior may offer an alternative, indirect method to assess the operant function of severe problem behavior. PMID:18468282

  14. Hydrothermal synthesis and characterization of Si and Sr co-substituted hydroxyapatite nanowires using strontium containing calcium silicate as precursors.

    PubMed

    Zhang, Na; Zhai, Dong; Chen, Lei; Zou, Zhaoyong; Lin, Kaili; Chang, Jiang

    2014-04-01

    In the absence of any organic surfactants and solvents, the silicon (Si) and strontium (Sr) co-substituted hydroxyapatite [Ca10(PO4)6(OH)2, Si/Sr-HAp] nanowires were synthesized via hydrothermal treatment of the Sr-containing calcium silicate (Sr-CS) powders as the precursors in trisodium phosphate (Na3PO4) aqueous solution. The morphology, phase, chemical compositions, lattice constants and the degradability of the products were characterized. The Si/Sr-HAp nanowires with diameter of about 60nm and up to 2μm in length were obtained after hydrothermal treatment of the Sr-CS precursors. The Sr and Si substitution amount of the HAp nanowires could be well regulated by facile tailoring the Sr substitution level of the precursors and the reaction ratio of the precursor/solution, respectively. The SiO4 tetrahedra and Sr(2+) ions occupied the crystal sites of the HAp, and the lattice constants increased apparently with the increase of the substitution amount. EDS mapping also suggested the uniform distribution of Si and Sr in the synthetic nanowires. Moreover, the Si/Sr-substitution apparently improved the degradability of the HAp materials. Our study suggested that the precursor transformation method provided a facile approach to synthesize the Si/Sr co-substituted HAp nanowires with controllable substitution amount, and the synthetic Si/Sr-HAp nanowires might be used as bioactive materials for hard tissue regeneration applications. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Ancient techniques for new materials

    NASA Technical Reports Server (NTRS)

    2000-01-01

    NASA is looking to biological techniques that are millions of years old to help it develop new materials and technologies for the 21st century. Sponsored by NASA, Viola Vogel, director of Washington University's Center for Nanotechnology and a principal investigator for the microgravity biotechnology program, is researching a monorail on a nanoscale to learn how to control translational motion of motor proteins in nonbiological environments in order to transport cargo between user-specified locations. Shear-deposition of Teflon on glass (top) is used in Viola Vogel's lab to create a nanogrooved surface. The topography controls the path that microtubules take as they shuttle nano-sized cargo between user-defined destinations.

  16. Bioactive Glass Nanoparticles: From Synthesis to Materials Design for Biomedical Applications

    PubMed Central

    Vichery, Charlotte; Nedelec, Jean-Marie

    2016-01-01

    Thanks to their high biocompatibility and bioactivity, bioactive glasses are very promising materials for soft and hard tissue repair and engineering. Because bioactivity and specific surface area intrinsically linked, the last decade has seen a focus on the development of highly porous and/or nano-sized materials. This review emphasizes the synthesis of bioactive glass nanoparticles and materials design strategies. The first part comprehensively covers mainly soft chemistry processes, which aim to obtain dispersible and monodispersed nanoparticles. The second part discusses the use of bioactive glass nanoparticles for medical applications, highlighting the design of materials. Mesoporous nanoparticles for drug delivery, injectable systems and scaffolds consisting of bioactive glass nanoparticles dispersed in a polymer, implant coatings and particle dispersions will be presented. PMID:28773412

  17. Method of texturing a superconductive oxide precursor

    DOEpatents

    DeMoranville, Kenneth L.; Li, Qi; Antaya, Peter D.; Christopherson, Craig J.; Riley, Jr., Gilbert N.; Seuntjens, Jeffrey M.

    1999-01-01

    A method of forming a textured superconductor wire includes constraining an elongated superconductor precursor between two constraining elongated members placed in contact therewith on opposite sides of the superconductor precursor, and passing the superconductor precursor with the two constraining members through flat rolls to form the textured superconductor wire. The method includes selecting desired cross-sectional shape and size constraining members to control the width of the formed superconductor wire. A textured superconductor wire formed by the method of the invention has regular-shaped, curved sides and is free of flashing. A rolling assembly for single-pass rolling of the elongated precursor superconductor includes two rolls, two constraining members, and a fixture for feeding the precursor superconductor and the constraining members between the rolls. In alternate embodiments of the invention, the rolls can have machined regions which will contact only the elongated constraining members and affect the lateral deformation and movement of those members during the rolling process.

  18. Cobalt- and iron-based nanoparticles hosted in SBA-15 mesoporous silica and activated carbon from biomass: Effect of modification procedure

    NASA Astrophysics Data System (ADS)

    Tsoncheva, Tanya; Genova, Izabela; Paneva, Daniela; Dimitrov, Momtchil; Tsyntsarski, Boyko; Velinov, Nicolay; Ivanova, Radostina; Issa, Gloria; Kovacheva, Daniela; Budinova, Temenujka; Mitov, Ivan; Petrov, Narzislav

    2015-10-01

    Ordered mesoporous silica of SBA-15 type and activated carbon, prepared from waste biomass (peach stones), are used as host matrix of nanosized iron and cobalt particles. The effect of preparation procedure on the state of loaded nanoparticles is in the focus of investigation. The obtained materials are characterized by Boehm method, low temperature physisorption of nitrogen, XRD, UV-Vis, FTIR, Mossbauer spectroscopy and temperature programmed reduction with hydrogen. The catalytic behaviour of the samples is tested in methanol decomposition. The dispersion, oxidative state and catalytic behaviour of loaded cobalt and iron nanoparticles are successfully tuned both by the nature of porous support and the metal precursor used during the samples preparation. Facile effect of active phase deposition from aqueous solution of nitrate precursors is assumed for activated carbon support. For the silica based materials the catalytic activity could be significantly improved when cobalt acetylacetonate is used during the modification. The complex effect of pore topology and surface functionality of different supports on the active phase formation is discussed.

  19. Nanosize Fe x O y @SBA-3: A Comparative Study Between Conventional and Microwave Assisted Synthesis.

    PubMed

    Barik, Sunita; Badamali, Sushanta K; Sahoo, Sagarika; Behera, Nandakishor; Dapurkar, Sudhir E

    2018-01-01

    The present study is focussed on development of highly dispersed nanosize iron oxide (FexOy) particles within the uniform mesopore channels of SBA-3. Herein we report a comparative study between conventional incipient wetness and microwave assisted synthesis routes adopted to devise nanoparticles. The developed materials are characterised by following X-ray diffraction, high resolution transmission electron microscopy, proton induced X-ray emission, diffuse reflectance UV-visible spectroscopy, thermogravimetry and Fourier transform infrared spectroscopy. Mesoporous siliceous SBA-3 was prepared at room temperature to obtain samples with good crystallinity and ordered pore structure. Pore channels of SBA-3 were used as nanoreactor for developing iron oxide nanoparticles. Iron oxide nanoparticles developed under microwave activation showed uniform distribution within the SBA-3 structure along with retaining the orderness of the pore architecture. On the contrary, iron oxides developed under incipient wetness method followed by conventional heating resulted in agglomeration of nanoparticles along with significant loss in SBA-3 pore structure. Proton induced X-ray emission studies revealed the extremely high purity of the samples and almost thrice higher amount of iron oxide particles are encapsulated within the host by microwave assisted preparation as compared to incipient/conventional heating method.

  20. Fabrication of compact and stable perovskite films with optimized precursor composition in the fast-growing procedure

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liu, Tanghao; Zhou, Yuanyuan; Hu, Qin

    The fast-growing procedure (FGP) provides a simple, high-yield and lead (Pb)-release free method to prepare perovskite films. In the FGP, the ultra-dilute perovskite precursor solution is drop-cast onto a hot (~240 degrees C) substrate, where a perovskite film grows immediately accompanied by the rapid evaporation of the host solvent. In this process, all the raw materials in the precursor solution are deposited into the final perovskite film. The potential pollution caused by Pb can be significantly reduced. Properties of the FGP-processed perovskite films can be modulated by the precursor composition. While CH3NH3Cl (MACl) affects the crystallization process and leads tomore » full surface coverage, CH(NH2)2I (FAI) enhances the thermal stability of the film. Based on the optimized precursor composition of PbI2(1-x)FAI xMACl, x=0.75, FGP-processed planar heterojunction perovskite solar cells exhibit power conversion efficiencies (PCEs) exceeding 15% with suppressed hysteresis and excellent reproducibility.« less

  1. Hotspot ignition using a Z-pinch precursor plasma in a magneto-inertial ICF scheme

    NASA Astrophysics Data System (ADS)

    Chittenden, J. P.; Vincent, P.; Jennings, C. A.; Ciardi, A.

    2006-01-01

    Precursor plasma flow is a common feature of wire array Z-pinches. The precursor flow represents a fraction of the mass of the array which arrives on the axis early in time and remains confined at high density by the inertia of further material bombarding the axis. Later on, the main implosion of the Z-pinch then compresses this precursor to substantially higher density. We show that if the same system can be generated with a Deuterium-Tritium plasma then the precursor provides an ideal target for a cylindrical magneto-inertial ICF scheme. The implosion of the DT Z-pinch produces a dense, low temperature shell which compressively heats the precursor target to high temperatures and tamps its expansion. The azimuthal magnetic field in the hotspot is sufficient to reduce the Larmor radius for the alpha particles to much less than the hotspot size, which dramatically reduces the pR required for ignition. A computational analysis of this approach is presented, including a study of the thermonuclear burn wave propagation. The robustness of the scheme with respect to instabilities, confinement time and drive parameters is examined. The results indicate that a high energy gain can be achieved using Z-pinches with 50-100 MA currents and a few hundred nanosecond rise-times. This work was partially supported by the U.S. Department of Energy through cooperative agreement DE-FC03-02NA00057.

  2. The influence of precursor addition order on the porosity of sol-gel bioactive glasses.

    PubMed

    Fernando, Delihta; Colon, Pierre; Cresswell, Mark; Journet, Catherine; Pradelle-Plasse, Nelly; Jackson, Phil; Grosgogeat, Brigitte; Attik, Nina

    2018-06-16

    The superior textural properties of sol-gel derived bioactive glasses compared to conventional melt quench glasses accounts for their accelerated bioactivity in vitro. Several studies have explored ways to improve the surface properties of sol-gel glasses in order to maximise their efficiency for bone and tooth regeneration. In this study, we investigated the effect of order of network modifying precursor addition on the textural properties of sol-gel derived bioactive glasses. The effect of precursor addition order on the glass characteristics was assessed by switching the order of network modifying precursor (calcium acetate monohydrate and sodium acetate anhydrous) addition for a fixed composition of bioactive glass (75SiO 2 :5CaO:10Na 2 O:10P 2 O 5 ). The results of this study showed that the order of precursor addition does influence the porosity of these glasses. For the glasses of a fixed composition and preparation conditions we achieved a doubling of surface area, a 1.5 times increase in pore volume and a 1.2 times decrease in pore size just by the mixing the network modifying precursors and adding them together in the sol-gel preparation. This simple and straightforward route adaptation to the preparation of bioactive glasses would allow us to enhance the textural properties of existing and novel composition of bioactive glasses and thus accelerate their bioactivity. Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.

  3. Sol-gel precursors and products thereof

    DOEpatents

    Warren, Scott C.; DiSalvo, Jr., Francis J.; Weisner, Ulrich B.

    2017-02-14

    The present invention provides a generalizable single-source sol-gel precursor capable of introducing a wide range of functionalities to metal oxides such as silica. The sol-gel precursor facilitates a one-molecule, one-step approach to the synthesis of metal-silica hybrids with combinations of biological, catalytic, magnetic, and optical functionalities. The single-source precursor also provides a flexible route for simultaneously incorporating functional species of many different types. The ligands employed for functionalizing the metal oxides are derived from a library of amino acids, hydroxy acids, or peptides and a silicon alkoxide, allowing many biological functionalities to be built into silica hybrids. The ligands can coordinate with a wide range of metals via a carboxylic acid, thereby allowing direct incorporation of inorganic functionalities from across the periodic table. Using the single-source precursor a wide range of functionalized nanostructures such as monolith structures, mesostructures, multiple metal gradient mesostructures and Stober-type nanoparticles can be synthesized. ##STR00001##

  4. Detection of Chemical Precursors of Explosives

    NASA Technical Reports Server (NTRS)

    Li, Jing

    2012-01-01

    Certain selected chemicals associated with terrorist activities are too unstable to be prepared in final form. These chemicals are often prepared as precursor components, to be combined at a time immediately preceding the detonation. One example is a liquid explosive, which usually requires an oxidizer, an energy source, and a chemical or physical mechanism to combine the other components. Detection of the oxidizer (e.g. H2O2) or the energy source (e.g., nitromethane) is often possible, but must be performed in a short time interval (e.g., 5 15 seconds) and in an environment with a very small concentration (e.g.,1 100 ppm), because the target chemical(s) is carried in a sealed container. These needs are met by this invention, which provides a system and associated method for detecting one or more chemical precursors (components) of a multi-component explosive compound. Different carbon nanotubes (CNTs) are loaded (by doping, impregnation, coating, or other functionalization process) for detecting of different chemical substances that are the chemical precursors, respectively, if these precursors are present in a gas to which the CNTs are exposed. After exposure to the gas, a measured electrical parameter (e.g. voltage or current that correlate to impedance, conductivity, capacitance, inductance, etc.) changes with time and concentration in a predictable manner if a selected chemical precursor is present, and will approach an asymptotic value promptly after exposure to the precursor. The measured voltage or current are compared with one or more sequences of their reference values for one or more known target precursor molecules, and a most probable concentration value is estimated for each one, two, or more target molecules. An error value is computed, based on differences of voltage or current for the measured and reference values, using the most probable concentration values. Where the error value is less than a threshold, the system concludes that the target

  5. Response under low-energy electron irradiation of a thin film of a potential copper precursor for focused electron beam induced deposition (FEBID)

    PubMed Central

    Sala, Leo; Szymańska, Iwona B; Dablemont, Céline; Lafosse, Anne

    2018-01-01

    Background: Focused electron beam induced deposition (FEBID) allows for the deposition of free standing material within nanometre sizes. The improvement of the technique needs a combination of new precursors and optimized irradiation strategies to achieve a controlled fragmentation of the precursor for leaving deposited material of desired composition. Here a new class of copper precursors is studied following an approach that probes some surface processes involved in the fragmentation of precursors. We use complexes of copper(II) with amines and perfluorinated carboxylate ligands that are solid and stable under ambient conditions. They are directly deposited on the surface for studying the fragmentation with surface science tools. Results: Infrared spectroscopy and high-resolution electron energy loss spectroscopy (HREELS) are combined to show that the precursor is able to spontaneously lose amine ligands under vacuum. This loss can be enhanced by mild heating. The combination of mass spectrometry and low-energy electron irradiation (0–15 eV) shows that full amine ligands can be released upon irradiation, and that fragmentation of the perfluorinated ligands is induced by electrons of energy as low as 1.5 eV. Finally, the cross section for this process is estimated from the temporal evolution in the experiments on electron-stimulated desorption (ESD). Conclusion: The release of full ligands under high vacuum and by electron irradiation, and the cross section measured here for ligands fragmentation allow one to envisage the use of the two precursors for FEBID studies. PMID:29379701

  6. Spray drying of silica microparticles for sustained release application with a new sol-gel precursor.

    PubMed

    Wang, Bifeng; Friess, Wolfgang

    2017-10-30

    A new precursor, tetrakis(2-methoxyethyl) orthosilicate (TMEOS) was used to fabricate microparticles for sustained release application, specifically for biopharmaceuticals, by spray drying. The advantages of TMEOS over the currently applied precursors are its water solubility and hydrolysis at moderate pH without the need of organic solvents or catalyzers. Thus a detrimental effect on biomolecular drug is avoided. By generating spray-dried silica particles encapsulating the high molecular weight model compound FITC-dextran 150 via the nano spray dryer Büchi-90, we demonstrated how formulation parameters affect and enable control of drug release properties. The implemented strategies to regulate release included incorporating different quantities of dextrans with varying molecular weight as well as adjusting the pH of the precursor solution to modify the internal microstructures. The addition of dextran significantly altered the released amount, while the release became faster with increasing dextran molecular weight. A sustained release over 35days could be achieved with addition of 60 kD dextran. The rate of FITC-Dextran 150 release from the dextran 60 containing particles decreased with higher precursor solution pH. In conclusion, the new precursor TMEOS presents a promising alternative sol-gel technology based carrier material for sustained release application of high molecular weight biopharmaceutical drugs. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Electrospun materials for affinity-based engineering and drug delivery

    NASA Astrophysics Data System (ADS)

    Sill, T. J.; von Recum, H. A.

    2015-10-01

    Electrospinning is a process which can quickly and cheaply create materials of high surface to volume and aspect ratios from many materials, however in application toward drug delivery this can be a strong disadvantage as well. Diffusion of drug is proportional to the thickness of that device. In moving from macro to micro to nano-sized electrospun materials drug release rates change to profiles that are too fast to be therapeutically beneficial. In this work we use molecular interactions to further control the rate of release beyond that capable of diffusion alone. To do this we create materials with molecular pockets, which can "hold" therapeutic drugs through a reversible interaction such as a host/guest complexation. Through these complexes we show we are able to impact delivery of drug from electrospun materials, and also apply them in tissue engineering for the reversible presentation of biomolecules on a fiber surface.

  8. Meditations on the ubiquity and mutability of nano-sized materials in the environment.

    PubMed

    Wiesner, Mark R; Lowry, Gregory V; Casman, Elizabeth; Bertsch, Paul M; Matson, Cole W; Di Giulio, Richard T; Liu, Jie; Hochella, Michael F

    2011-11-22

    A wide variety of nanomaterials can be found naturally occurring in the environment, although finding and characterizing these materials remains a challenge due to their size. Recent studies in the field have shown that natural nanomaterials are common in many geochemical systems. In this issue of ACS Nano, Hutchison and co-workers make us realize that manmade nanomaterials can often be practically identical to those that spontaneously form in the environment. This Perspective discusses the prevalence of nanomaterials in nature, including anthropogenic and naturally occurring nanomaterials, and the dynamic behavior of these materials in the environment. © 2011 American Chemical Society

  9. Natural cotton as precursor for the refractory boron carbide—a hydrothermal synthesis and characterization

    NASA Astrophysics Data System (ADS)

    Saritha Devi, H. V.; Swapna, M. S.; Raj, Vimal; Ambadas, G.; Sankararaman, S.

    2018-01-01

    Boron carbide (B4C) is an excellent covalent carbide that finds applications in industries and nuclear power plants. The present synthesis methods of boron carbide are expensive and involve the use of toxic chemicals that adversely affect environment. In the present work, we report for the first time the use of the hydrothermal method for converting the cellulose from cotton as the carbon precursor for B4C. The carbon precursor is converted into functionalized porous carbonaceous material by hydrothermal treatment followed by sodium borohydride. It is further treated with boric acid to make it a B4C precursor. The precursor is characterized by UV-visible diffuse reflectance, Raman, Fourier transform infrared, photoluminescent and energy dispersive spectroscopy. The morphology and structure analysis is carried out using field emission scanning electron microscopy and x-ray diffraction techniques. The results of structural and optical characterization of the sample synthesized are compared with the commercial B4C. The thermal stability of the sample is studied by thermogravimetric analysis. The sample annealed at 700 °C is found to be B4C devoid of amorphous carbon with a yield of 44.7%. The analysis reveals the formation of boron carbide from the sample.

  10. Nanosized Thin SnO2 Layers Doped with Te and TeO2 as Room Temperature Humidity Sensors

    PubMed Central

    Georgieva, Biliana; Podolesheva, Irena; Spasov, Georgy; Pirov, Jordan

    2014-01-01

    In this paper the humidity sensing properties of layers prepared by a new method for obtaining doped tin oxide are studied. Different techniques—SEM, EDS in SEM, TEM, SAED, AES and electrical measurements—are used for detailed characterization of the thin layers. The as-deposited layers are amorphous with great specific area and low density. They are built up of a fine grained matrix, consisting of Sn- and Te-oxides, and a nanosized dispersed phase of Te, Sn and/or SnTe. The chemical composition of both the matrix and the nanosized particles depends on the ratio RSn/Te and the evaporation conditions. It is shown that as-deposited layers with RSn/Te ranging from 0.4 to 0.9 exhibit excellent characteristics as humidity sensors operating at room temperature—very high sensitivity, good selectivity, fast response and short recovery period. Ageing tests have shown that the layers possess good long-term stability. Results obtained regarding the type of the water adsorption on the layers' surface help better understand the relation between preparation conditions, structure, composition and humidity sensing properties. PMID:24854359

  11. Earthquakes: hydrogeochemical precursors

    USGS Publications Warehouse

    Ingebritsen, Steven E.; Manga, Michael

    2014-01-01

    Earthquake prediction is a long-sought goal. Changes in groundwater chemistry before earthquakes in Iceland highlight a potential hydrogeochemical precursor, but such signals must be evaluated in the context of long-term, multiparametric data sets.

  12. Microbial surfactants: fundamentals and applicability in the formulation of nano-sized drug delivery vectors.

    PubMed

    Rodrigues, Ligia R

    2015-07-01

    Microbial surfactants, so-called biosurfactants, comprise a wide variety of structurally distinct amphipathic molecules produced by several microorganisms. Besides exhibiting surface activity at the interfaces, these molecules present powerful characteristics including high biodegradability, low toxicity and special biological activities (e.g. antimicrobial, antiviral, anticancer, among others), that make them an alternative to their chemical counterparts. Several medical-related applications have been suggested for these molecules, including some reports on their potential use in the formulation of nano-sized drug delivery vectors. However, despite their promises, due to the generalized lack of knowledge on microbial surfactants phase behavior and stability under diverse physicochemical conditions, these applications remain largely unexplored, thus representing an exciting field of research. These nano-sized vectors are a powerful approach towards the current medical challenges regarding the development of efficient and targeted treatments for several diseases. In this review, a special emphasis will be given to nanoparticles and microemulsions. Nanoparticles are very auspicious as their size, shape and stability can be manipulated by changing the environmental conditions. On the other hand, the easiness of formulation, as well as the broad possibilities of administration justifies the recent popularity of the microemulsions. Notwithstanding, both vector types still require further developments to overcome some critical limitations related with toxicity and costs, among others. Such developments may include the search for other system components, as the microbial surfactants, that can display improved features. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Nazca-South America Subduction Zone Reflectivity from P'P' Precursors

    NASA Astrophysics Data System (ADS)

    Gu, Y. J.; Schultz, R.

    2012-12-01

    Much of what is known about mantle owes to the interpretation of its reflectivity structure. On the global scale mantle stratifications have been attributed to mineralogical phase changes of olivine; two widely observed examples are the 410 and 660 km discontinuities. Among the various seismological tools, results from longer-period SS/PP precursors and high frequency receiver functions are routinely compared to increase the confidence of the recovered mantle stratifications. The former are lower frequency approaches with complex Fresnel zones, while constraints on receiver distribution hinder analysis in oceanic regions for the latter. P'P' precursors are a promising high frequency alternative, capable of resolving small-scale structures (resolution of ~5 km vertically, 200 km laterally) in the mantle, owing to its short-period nature (~1Hz), shallow angle of incidence and nearly symmetric Fresnel zone. However, P'P' precursors are known for several complications: phase triplication (PKiKPPKiKP, PKIKPPKIKP, PKPPKPab and PKPPKPbc) and the maximum-phase Fresnel zones result in strong scattering and asymmetric arrivals. Much of these concerns are alleviated through revamped processing techniques involving stacking, deconvolution, Radon transform and migration. We utilize P'P' precursors to constrain the mantle structure and layering beneath the Nazca-South America subduction zone. Our migration profiles reveal both olivine (e.g., 410, 520, 660) and garnet related transitions in the mantle, with constraints on the sharpness of these transitions. Observations of a depressed 660 are attributed to thermal variations, showing the spatial extent of the impinging Nazca slab. Prominent 520 arrivals near subducted slab material suggest this transition is sharpened to a thickness resonant with P'P' (~10km). The possibility of chemical heterogeneity is evidenced near the top of the mantle transition zone through complicated 410 amplitudes. The existence, depth, sharpness and

  14. Silsesquioxanes as precursors to ceramic composites

    NASA Technical Reports Server (NTRS)

    Hurwitz, Frances I.; Hyatt, Lizbeth H.; Gorecki, Joy; Damore, Lisa

    1987-01-01

    Silsesquioxanes having the general structure RSiO sub 1.5, where R = methyl, propyl, or phenyl, melt flow at 70 to 100 C. Above 100 C, free -OH groups condense. At 225 C further crosslinking occurs, and the materials form thermosets. Pyrolysis, with accompanying loss of volatiles, takes place at nominally 525 C. At higher temperatures, the R group serves as an internal carbon soruce for carbo-thermal reduction to SiC accompanied by the evolution of CO. By blending silsesquioxanes with varying R groups, both the melt rheology and composition of the fired ceramic can be controlled. Fibers can be spun from the melt which are stable in argon in 1400 C. The silsesquioxanes also were used as matrix precursors for Nicalon and alpha-SiC platelet reinforced composites.

  15. Direct conversion of bio-ethanol to isobutene on nanosized Zn(x)Zr(y)O(z) mixed oxides with balanced acid-base sites.

    PubMed

    Sun, Junming; Zhu, Kake; Gao, Feng; Wang, Chongmin; Liu, Jun; Peden, Charles H F; Wang, Yong

    2011-07-27

    We report the design and synthesis of nanosized Zn(x)Zr(y)O(z) mixed oxides for direct and high-yield conversion of bio-ethanol to isobutene (~83%). ZnO is addded to ZrO(2) to selectively passivate zirconia's strong Lewis acidic sites and weaken Brönsted acidic sites, while simultaneously introducing basicity. As a result, the undesired reactions of bio-ethanol dehydration and acetone polymerization/coking are suppressed. Instead, a surface basic site-catalyzed ethanol dehydrogenation to acetaldehyde, acetaldehyde to acetone conversion via a complex pathway including aldol-condensation/dehydrogenation, and a Brönsted acidic site-catalyzed acetone-to-isobutene reaction pathway dominates on the nanosized Zn(x)Zr(y)O(z) mixed oxide catalyst, leading to a highly selective process for direct conversion of bio-ethanol to isobutene.

  16. Effect of Precursor Selection on the Photocatalytic Performance of Indium Oxide Nanomaterials for Gas-Phase CO 2 Reduction

    DOE PAGES

    Hoch, Laura B.; He, Le; Qiao, Qiao; ...

    2016-06-01

    Nonstoichiometric indium oxide nanoparticles, In 2O 3–x(OH)y, have been shown to function as active photocatalysts for gas-phase CO 2 reduction under simulated solar irradiation. We demonstrate that the choice of starting material has a strong effect on the photocatalytic activity of indium oxide nanoparticles. We also examine three indium oxide materials prepared via the thermal decomposition of either indium(III) hydroxide or indium(III) nitrate and correlate their stability and photocatalytic activity to the number and type of defect present in the material. Furthermore, we use 13CO 2 isotope-tracing experiments to clearly identify the origins of the observed carbon-containing products. Significantly, wemore » find that the oxidizing nature of the precursor anion has a substantial impact on the defect formation within the sample. Our study demonstrates the importance of surface defects in designing an active heterogeneous photocatalyst and provides valuable insight into key parameters for the precursor design, selection, and performance optimization of materials for gas-phase CO 2 reduction.« less

  17. Surface Chemistry and Precursor Material Effects on the Performance of Pyrolyzed Nanofibers as Anodes for Lithium-ion Batteries

    NASA Astrophysics Data System (ADS)

    Loebl, Andrew James

    resulted in a nearly 50% reduction in reversible lithium storage. Thinner coatings of alumina had a less dramatic effect on both the irreversible capacity losses and the reversible discharge capacity. A coating of ten cycles of alumina at a temperature of 150 °C resulted in a 17% reduction in irreversible capacity with negligible impact on the reversible capacity. Hybrid aluminum-organic films grown by molecular layer deposition also reduced irreversible lithium losses. The largest reduction was 23% for electrodes coated with 40 cycles of the alucone material. For all thicknesses studied these hybrid films delivered less improvement than the alumina grown by atomic layer deposition, with poor reversible lithium storage capacity available at high charging and discharging currents. Second, polyacrylonitrile has served as the precursor for electrospun composite electrodes because of its ease of processing and well-known carbonization process. Polyimides represent a family of polymers for which the material properties can be tailored by careful monomer selection. These polymers were used as the non-woven matrix to create materials capable of delivering a larger percentage of their maximum reversible capacities at high currents when compared to polyacrylonitrile-based electrodes. These materials had a more graphitic structure based on Raman spectroscopy, and resulted in lower irreversible capacity losses than polyacrylonitrile-based fibers for fibers based on pyromellitic dianhydride and p-phenylene diamine.

  18. Synthesis of nano-sized ZnO particles by co-precipitation method with variation of heating time

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Purwaningsih, S. Y., E-mail: sriyanisaputri@gmail.com; Pratapa, S.; Triwikantoro

    Zinc oxide powders have been synthesized by a co-precipitation method at low temperature (85 °C), using zinc acetate dihydrate, ammonia, hydrochloric acid solutions as the reactants. A number of process parameters such as reaction temperature, solution basicity or pH and heating time are the main factors affecting the morphology and physical properties of the ZnO nanostructures. In this work the effect of heating time on the morphology and particles size were studied. The as-synthesized ZnO powders were characterized using transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques. The samples were also analyzed using Fourier transform infrared (FTIR). Rietveld refinementmore » of XRD data confirms that ZnO crystallizes in the hexagonal wurtzite structure with high degree of purity and the (101) plane predominant. The XRD results show that the average crystallite sizes were about 66, 27 and 12 nm for 3, 4 and 5 h of heating times, respectively. The XRD analysis indicated that a fraction of nano-sized ZnO powders were in the form of aggregates, which was also verified by TEM image. The TEM photograph demonstrated that the nano-sized ZnO particles were a pseudo-spherical shape.« less

  19. Method for Waterproofing Ceramic Materials

    NASA Technical Reports Server (NTRS)

    Cagliostro, Domenick E. (Inventor); Hsu, Ming-Ta S. (Inventor)

    1998-01-01

    Hygroscopic ceramic materials which are difficult to waterproof with a silane, substituted silane or silazane waterproofing agent, such as an alumina containing fibrous, flexible and porous, fibrous ceramic insulation used on a reentry space vehicle, are rendered easy to waterproof if the interior porous surface of the ceramic is first coated with a thin coating of silica. The silica coating is achieved by coating the interior surface of the ceramic with a silica precursor converting the precursor to silica either in-situ or by oxidative pyrolysis and then applying the waterproofing agent to the silica coated ceramic. The silica precursor comprises almost any suitable silicon containing material such as a silane, silicone, siloxane, silazane and the like applied by solution, vapor deposition and the like. If the waterproofing is removed by e.g., burning, the silica remains and the ceramic is easily rewaterproofed. An alumina containing TABI insulation which absorbs more that five times its weight of water, absorbs less than 10 wt. % water after being waterproofed according to the method of the invention.

  20. Nanoscale Design of Nano-Sized Particles in Shape-Memory Polymer Nanocomposites Driven by Electricity

    PubMed Central

    Lu, Haibao; Huang, Wei Min; Liang, Fei; Yu, Kai

    2013-01-01

    In the last few years, we have witnessed significant progress in developing high performance shape memory polymer (SMP) nanocomposites, in particular, for shape recovery activated by indirect heating in the presence of electricity, magnetism, light, radio frequency, microwave and radiation, etc. In this paper, we critically review recent findings in Joule heating of SMP nanocomposites incorporated with nanosized conductive electromagnetic particles by means of nanoscale control via applying an electro- and/or magnetic field. A few different nanoscale design principles to form one-/two-/three- dimensional conductive networks are discussed. PMID:28788303

  1. Method of preparation of carbon materials for use as electrodes in rechargeable batteries

    DOEpatents

    Doddapaneni, N.; Wang, J.C.F.; Crocker, R.W.; Ingersoll, D.; Firsich, D.W.

    1999-03-16

    A method is described for producing carbon materials for use as electrodes in rechargeable batteries. Electrodes prepared from these carbon materials exhibit intercalation efficiencies of {approx_equal} 80% for lithium, low irreversible loss of lithium, long cycle life, are capable of sustaining a high rates of discharge and are cheap and easy to manufacture. The method comprises a novel two-step stabilization process in which polymeric precursor materials are stabilized by first heating in an inert atmosphere and subsequently heating in air. During the stabilization process, the polymeric precursor material can be agitated to reduce particle fusion and promote mass transfer of oxygen and water vapor. The stabilized, polymeric precursor materials can then be converted to a synthetic carbon, suitable for fabricating electrodes for use in rechargeable batteries, by heating to a high temperature in a flowing inert atmosphere. 4 figs.

  2. Method of preparation of carbon materials for use as electrodes in rechargeable batteries

    DOEpatents

    Doddapaneni, Narayan; Wang, James C. F.; Crocker, Robert W.; Ingersoll, David; Firsich, David W.

    1999-01-01

    A method of producing carbon materials for use as electrodes in rechargeable batteries. Electrodes prepared from these carbon materials exhibit intercalation efficiencies of .apprxeq.80% for lithium, low irreversible loss of lithium, long cycle life, are capable of sustaining a high rates of discharge and are cheap and easy to manufacture. The method comprises a novel two-step stabilization process in which polymeric precursor materials are stabilized by first heating in an inert atmosphere and subsequently heating in air. During the stabilization process, the polymeric precursor material can be agitated to reduce particle fusion and promote mass transfer of oxygen and water vapor. The stabilized, polymeric precursor materials can then be converted to a synthetic carbon, suitable for fabricating electrodes for use in rechargeable batteries, by heating to a high temperature in a flowing inert atmosphere.

  3. Descriptive and Experimental Analyses of Potential Precursors to Problem Behavior

    PubMed Central

    Borrero, Carrie S.W; Borrero, John C

    2008-01-01

    We conducted descriptive observations of severe problem behavior for 2 individuals with autism to identify precursors to problem behavior. Several comparative probability analyses were conducted in addition to lag-sequential analyses using the descriptive data. Results of the descriptive analyses showed that the probability of the potential precursor was greater given problem behavior compared to the unconditional probability of the potential precursor. Results of the lag-sequential analyses showed a marked increase in the probability of a potential precursor in the 1-s intervals immediately preceding an instance of problem behavior, and that the probability of problem behavior was highest in the 1-s intervals immediately following an instance of the precursor. We then conducted separate functional analyses of problem behavior and the precursor to identify respective operant functions. Results of the functional analyses showed that both problem behavior and the precursor served the same operant functions. These results replicate prior experimental analyses on the relation between problem behavior and precursors and extend prior research by illustrating a quantitative method to identify precursors to more severe problem behavior. PMID:18468281

  4. Synthesis of Sol-Gel Precursors for Ceramics from Lunar and Martian Soil Simulars

    NASA Technical Reports Server (NTRS)

    Sibille, L.; Gavira-Gallardo, J. A.; Hourlier-Bahloul, D.

    2004-01-01

    Recent NASA mission plans for the human exploration of our Solar System has set new priorities for research and development of technologies necessary to enable a long-term human presence on the Moon and Mars. The recovery and processing of metals and oxides from mineral sources on other planets is under study to enable use of ceramics, glasses and metals by explorer outposts. We report initial results on the production of sol-gel precursors for ceramic products using mineral resources available in martian or lunar soil. The presence of SO2, TiO2, and Al2O3 in both martian (44 wt.% SiO2, 1 wt.% TiO2, 7 wt.% Al2O3) and lunar (48 wt.% SiO2, 1.5 wt.% TiO2, 16 wt.% Al2O3) soils and the recent developments in chemical processes to solubilize silicates using organic reagents and relatively little energy indicate that such an endeavor is possible. In order to eliminate the risks involved in the use of hydrofluoric acid to dissolve silicates, two distinct chemical routes are investigated to obtain soluble silicon oxide precursors from lunar and martian soil simulars. Clear solutions of sol-gel precursors have been obtained by dissolution of silica from lunar soil similar JSC-1 in basic ethylene glycol (C2H4(OH)2) solutions to form silicon glycolates. Similarly, sol-gel solutions produced from martian soil simulars reveal higher contents of iron oxides. Characterization of the precursor molecules and efforts to further concentrate and hydrolyze the products to obtain gel materials will be presented for evaluation as ceramic precursors.

  5. Synthesis of Sol-Gel Precursors for Ceramics from Lunar and Martian Soil Simulars

    NASA Technical Reports Server (NTRS)

    Sibille, L.; Gavira-Gallardo, J. A.; Hourlier-Bahloul, D.

    2003-01-01

    Recent NASA mission plans for the human exploration of our Solar System has set new priorities for research and development of technologies necessary to enable a long-term human presence on the Moon and Mars. The recovery and processing of metals and oxides from mineral sources on other planets is under study to enable use of ceramics, glasses and metals by explorer outposts. We report initial results on the production of sol-gel precursors for ceramic products using mineral resources available in martian or lunar soil. The presence of SiO2, TiO2, and Al2O3 in both martian (44 wt.% SiO2, 1 wt.% TiO2,7 wt.% Al2O3) and lunar (48 wt.% SiO2, 1.5 wt.% TiO2, 16 wt.% Al2O3) soils and the recent developments in chemical processes to solubilize silicates using organic reagents and relatively little energy indicate that such an endeavor is possible. In order to eliminate the risks involved in the use of hydrofluoric acid to dissolve silicates, two distinct chemical routes are investigated to obtain soluble silicon oxide precursors from lunar and martian soil simulars. Clear solutions of sol-gel precursors have been obtained by dissolution of silica from lunar soil simular in basic ethylene glycol (C2H4(OH)2) solutions to form silicon glycolates. Similarly, sol-gel solutions produced from martian soil simulars reveal higher contents of iron oxides. The elemental composition and structure of the precursor molecules were characterized. Further concentration and hydrolysis of the products was performed to obtain gel materials for evaluation as ceramic precursors.

  6. Perfluoroalkyl Acids (PFAAs) and Selected Precursors in the Baltic Sea Environment: Do Precursors Play a Role in Food Web Accumulation of PFAAs?

    PubMed

    Gebbink, Wouter A; Bignert, Anders; Berger, Urs

    2016-06-21

    The present study examined the presence of perfluoroalkyl acids (PFAAs) and selected precursors in the Baltic Sea abiotic environment and guillemot food web, and investigated the relative importance of precursors in food web accumulation of PFAAs. Sediment, water, zooplankton, herring, sprat, and guillemot eggs were analyzed for perfluoroalkane sulfonic acids (PFSAs; C4,6,8,10) and perfluoroalkyl carboxylic acids (PFCAs; C6-15) along with six perfluoro-octane sulfonic acid (PFOS) precursors and 11 polyfluoroalkyl phosphoric acid diesters (diPAPs). FOSA, FOSAA and its methyl and ethyl derivatives (Me- and EtFOSAA), and 6:2/6:2 diPAP were detected in sediment and water. While FOSA and the three FOSAAs were detected in all biota, a total of nine diPAPs were only detected in zooplankton. Concentrations of PFOS precursors and diPAPs exceeded PFOS and PFCA concentrations, respectively, in zooplankton, but not in fish and guillemot eggs. Although PFOS precursors were present at all trophic levels, they appear to play a minor role in food web accumulation of PFOS based on PFOS precursor/PFOS ratios and PFOS and FOSA isomer patterns. The PFCA pattern in fish could not be explained by the intake pattern based on PFCAs and analyzed precursors, that is, diPAPs. Exposure to additional precursors might therefore be a dominant exposure pathway compared to direct PFCA exposure for fish.

  7. Polyether ether ketone implants achieve increased bone fusion when coated with nano-sized hydroxyapatite: a histomorphometric study in rabbit bone.

    PubMed

    Johansson, Pär; Jimbo, Ryo; Naito, Yoshihito; Kjellin, Per; Currie, Fredrik; Wennerberg, Ann

    2016-01-01

    Polyether ether ketone (PEEK) possesses excellent mechanical properties similar to those of human bone and is considered the best alternative material other than titanium for orthopedic spine and trauma implants. However, the deficient osteogenic properties and the bioinertness of PEEK limit its fields of application. The aim of this study was to limit these drawbacks by coating the surface of PEEK with nano-scaled hydroxyapatite (HA) minerals. In the study, the biological response to PEEK, with and without HA coating, was investigated. Twenty-four screw-like and apically perforated implants in the rabbit femur were histologically evaluated at 3 weeks and 12 weeks after surgery. Twelve of the 24 implants were HA coated (test), and the remaining 12 served as uncoated PEEK controls. At 3 weeks and 12 weeks, the mean bone-implant contact was higher for test compared to control (P<0.05). The bone area inside the threads was comparable in the two groups, but the perforating hole showed more bone area for the HA-coated implants at both healing points (P<0.01). With these results, we conclude that nano-sized HA coating on PEEK implants significantly improved the osteogenic properties, and in a clinical situation this material composition may serve as an implant where a rapid bone fusion is essential.

  8. Crosslinked polymeric dielectric materials and electronic devices incorporating same

    NASA Technical Reports Server (NTRS)

    Facchetti, Antonio (Inventor); Suh, legal representative, Nae-Jeong (Inventor); Marks, Tobin J. (Inventor); Choi, Hyuk-Jin (Inventor); Wang, Zhiming (Inventor)

    2012-01-01

    Solution-processable dielectric materials are provided, along with precursor compositions and processes for preparing the same. Composites and electronic devices including the dielectric materials also are provided.

  9. Method for dispersing catalyst onto particulate material

    DOEpatents

    Utz, Bruce R.; Cugini, Anthony V.

    1992-01-01

    A method for dispersing finely divided catalyst precursors onto the surface of coal or other particulate material includes the steps of forming a wet paste mixture of the particulate material and a liquid solution containing a dissolved transition metal salt, for instance a solution of ferric nitrate. The wet paste mixture is in a state of incipient wetness with all of this solution adsorbed onto the surfaces of the particulate material without the presence of free moisture. On adding a precipitating agent such as ammonia, a catalyst precursor such as hydrated iron oxide is deposited on the surfaces of the coal. The catalyst is activated by converting it to the sulfide form for the hydrogenation or direct liquefaction of the coal.

  10. Advances in aluminum powder usage as an energetic material and applications for rocket propellant

    NASA Astrophysics Data System (ADS)

    Sadeghipour, S.; Ghaderian, J.; Wahid, M. A.

    2012-06-01

    Energetic materials have been widely used for military purposes. Continuous research programs are performing in the world for the development of the new materials with higher and improved performance comparing with the available ones in order to fulfill the needs of the military in future. Different sizes of aluminum powders are employed to produce composite rocket propellants with the bases of Ammonium Perchlorate (AP) and Hydroxyl-Terminated-Polybutadiene (HTPB) as oxidizer and binder respectively. This paper concentrates on recent advances in using aluminum as an energetic material and the properties and characteristics pertaining to its combustion. Nano-sized aluminum as one of the most attractable particles in propellants is discussed particularly.

  11. Cellulose nanocrystals, nanofibers, and their composites as renewable smart materials

    NASA Astrophysics Data System (ADS)

    Kim, Jaehwan; Zhai, Lindong; Mun, Seongcheol; Ko, Hyun-U.; Yun, Young-Min

    2015-04-01

    Cellulose is one of abundant renewable biomaterials in the world. Over 1.5 trillion tons of cellulose is produced per year in nature by biosynthesis, forming microfibrils which in turn aggregate to form cellulose fibers. Using new effective methods these microfibrils can be disintegrated from the fibers to nanosized materials, so called cellulose nanocrystal (CNC) and cellulose nanofiber (CNF). The CNC and CNF have extremely good strength properties, dimensional stability, thermal stability and good optical properties on top of their renewable behavior, which can be a building block of new materials. This paper represents recent advancement of cellulose nanocrystals and cellulose nanofibers, followed by their possibility for smart materials. Natural behaviors, extraction, modification of cellulose nanocrystals and fibers are explained and their synthesis with nanomaterials is introduced, which is necessary to meet the technological requirements for smart materials. Also, its challenges are addressed.

  12. SEARCH FOR PRECURSOR ERUPTIONS AMONG TYPE IIB SUPERNOVAE

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Strotjohann, Nora L.; Ofek, Eran O.; Gal-Yam, Avishay

    2015-10-01

    The progenitor stars of several Type IIb supernovae (SNe) show indications of extended hydrogen envelopes. These envelopes might be the outcome of luminous energetic pre-explosion events, so-called precursor eruptions. We use the Palomar Transient Factory (PTF) pre-explosion observations of a sample of 27 nearby SNe IIb to look for such precursors during the final years prior to the SN explosion. No precursors are found when combining the observations in 15-day bins, and we calculate the absolute-magnitude-dependent upper limit on the precursor rate. At the 90% confidence level, SNe IIb have on average <0.86 precursors as bright as an absolute R-bandmore » magnitude of −14 in the final 3.5 years before the explosion and <0.56 events over the final year. In contrast, precursors among SNe IIn have a ≳5 times higher rate. The kinetic energy required to unbind a low-mass stellar envelope is comparable to the radiated energy of a few-weeks-long precursor that would be detectable for the closest SNe in our sample. Therefore, mass ejections, if they are common in such SNe, are radiatively inefficient or have durations longer than months. Indeed, when using 60-day bins, a faint precursor candidate is detected prior to SN 2012cs (∼2% false-alarm probability). We also report the detection of the progenitor of SN 2011dh that does not show detectable variability over the final two years before the explosion. The suggested progenitor of SN 2012P is still present, and hence is likely a compact star cluster or an unrelated object.« less

  13. Natural precursor based hydrothermal synthesis of sodium carbide for reactor applications

    NASA Astrophysics Data System (ADS)

    Swapna, M. S.; Saritha Devi, H. V.; Sebastian, Riya; Ambadas, G.; Sankararaman, S.

    2017-12-01

    Carbides are a class of materials with high mechanical strength and refractory nature which finds a wide range of applications in industries and nuclear reactors. The existing synthesis methods of all types of carbides have problems in terms of use of toxic chemical precursors, high-cost, etc. Sodium carbide (Na2C2) which is an alkali metal carbide is the least explored one and also that there is no report of low-cost and low-temperature synthesis of sodium carbide using the eco-friendly, easily available natural precursors. In the present work, we report a simple low-cost, non-toxic hydrothermal synthesis of refractory sodium carbide using the natural precursor—Pandanus. The formation of sodium carbide along with boron carbide is evidenced by the structural and morphological characterizations. The sample thus synthesized is subjected to field emission scanning electron microscopy (FESEM), x-ray powder diffraction (XRD), ultraviolet (UV)—visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), Raman, and photoluminescent (PL) spectroscopic techniques.

  14. Deposition of Ni nanoparticles onto porous supports using supercritical CO2: effect of the precursor and reduction methodology.

    PubMed

    Morère, Jacobo; Royuela, Sergio; Asensio, Guillermo; Palomino, Pablo; Enciso, Eduardo; Pando, Concepción; Cabañas, Albertina

    2015-12-28

    The deposition of Ni nanoparticles into porous supports is very important in catalysis. In this paper, we explore the use of supercritical CO(2) (scCO(2)) as a green solvent to deposit Ni nanoparticles on mesoporous SiO2 SBA-15 and a carbon xerogel. The good transport properties of scCO(2) allowed the efficient penetration of metal precursors dissolved in scCO(2) within the pores of the support without damaging its structure. Nickel hexafluoroacetylacetonate hydrate, nickel acetylacetonate, bis(cyclopentadienyl)nickel, Ni(NO(3))2⋅6H(2)O and NiCl(2)⋅6H(2)O were tried as precursors. Different methodologies were used: impregnation in scCO(2) and reduction in H(2)/N(2) at 400°C and low pressure, reactive deposition using H(2) at 200-250°C in scCO(2) and reactive deposition using ethanol at 150-200°C in scCO(2). The effect of precursor and methodology on the nickel particle size and the material homogeneity (on the different substrates) was analysed. This technology offers many opportunities in the preparation of metal-nanostructured materials. © 2015 The Author(s).

  15. The importance of “going nano” for high power battery materials

    NASA Astrophysics Data System (ADS)

    Bresser, Dominic; Paillard, Elie; Copley, Mark; Bishop, Peter; Winter, Martin; Passerini, Stefano

    2012-12-01

    The electrochemical performance of spinel Li4Ti5O12 (LTO) nanoparticles synthesized by flame spray pyrolysis with an average diameter of approximately 20-30 nm is reported in this manuscript and compared with that of micro-sized LTO particles (1-2 μm) formed by a thermal post-treatment of the nanoparticles. The significantly advanced high rate capability of nano-sized LTO is evidenced by the results from the galvanostatic tests with applied current densities of up to 17.5 A g-1, corresponding to a full (dis-)charge of the cell within less than 40 s. For nano-sized LTO, specific capacities of 115 and 70 mAh g-1 were obtained for applied rates of 10 C and 100 C, respectively, thus confirming the essential influence of particle size of lithium titanate on its high rate capability and practical power density. Moreover, a capacity retention of around 94.8% was observed after 1000 cycles at 10 C, presenting LTO nanoparticles synthesized by FSP as highly promising anode material for high power lithium-ion battery applications.

  16. Evaluation of heavy metals in hazardous automobile shredder residue thermal residue and immobilization with novel nano-size calcium dispersed reagent.

    PubMed

    Lee, Chi-Hyeon; Truc, Nguyen Thi Thanh; Lee, Byeong-Kyu; Mitoma, Yoshiharu; Mallampati, Srinivasa Reddy

    2015-10-15

    This study was conducted to synthesize and apply a nano-size calcium dispersed reagent as an immobilization material for heavy metal-contaminated automobile shredder residues (ASR) dust/thermal residues in dry condition. Simple mixing with a nanometallic Ca/CaO/PO4 dispersion mixture immobilized 95-100% of heavy metals in ASR dust/thermal residues (including bottom ash, cavity ash, boiler and bag filter ash). The quantity of heavy metals leached from thermal residues after treatment by nanometallic Ca/CaO/PO4 was lower than the Korean standard regulatory limit for hazardous waste landfills. The morphology and elemental composition of the nanometallic Ca/CaO-treated ASR residue were characterized by field emission scanning election microscopy combined with electron dispersive spectroscopy (FE-SEM/EDS). The results indicated that the amounts of heavy metals detectable on the ASR thermal residue surface decreased and the Ca/PO4 mass percent increased. X-ray diffraction (XRD) pattern analysis indicated that the main fraction of enclosed/bound materials on ASR residue included Ca/PO4- associated crystalline complexes, and that immobile Ca/PO4 salts remarkably inhibited the desorption of heavy metals from ASR residues. These results support the potential use of nanometallic Ca/CaO/PO4 as a simple, suitable and highly efficient material for the gentle immobilization of heavy metals in hazardous ASR thermal residue in dry condition. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Effect of toothpaste with nano-sized trimetaphosphate on dental caries: In situ study.

    PubMed

    Danelon, Marcelle; Pessan, Juliano Pelim; Neto, Francisco Nunes Souza; de Camargo, Emerson Rodrigues; Delbem, Alberto Carlos Botazzo

    2015-07-01

    This in situ study was to evaluate the remineralizing effect of a fluoride toothpaste supplemented with nano-sized sodium trimetaphosphate (TMP). This blind and cross-over study was performed in 4 phases of 3 days each. Twelve subjects used palatal appliances containing four bovine enamel blocks with artificial caries lesions. Volunteers were randomly assigned into the following treatment groups: Placebo (without F and TMP); 1100 ppm F (1100), 1100 supplemented with 3% micrometric TMP (1100 TMP) and with nano-sized TMP (1100 TMPnano). Volunteers were instructed to brush their natural teeth with the palatal appliances in the mouth during 1min (3 times/day), so that blocks were treated with natural slurries of toothpastes. After each phase, the percentage of surface hardness recovery (%SHR), integrated mineral recovery (IMR) and integrated differential mineral area profile (ΔIMR) in enamel lesions were calculated. F in enamel was also determined. Data were analyzed by ANOVA and Student-Newman-Keuls test. Enamel surface became 20% harder when treated with 1100 TMPnano in comparison with 1100 (p<0.001). 1100 TMPnano showed remineralizing capacity (IMR; ΔIMR) 66% higher when compared with 1100 TMP (p<0.001). Enamel F uptake in the 1100 TMPnano group was 2-fold higher when compared to its counterpart without TMP (p<0.001). The addition of 3% TMPnano to a conventional toothpaste was able to promote an additional remineralizing effect of artificial caries lesions. Toothpaste containing 1100 ppm F associated with TMPnano showed a potential of higher remineralization to 1100 ppm F and 1100 ppm F micrometric TMP. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Preparation of hemoglobin-loaded nano-sized particles with porous structure as oxygen carriers.

    PubMed

    Zhao, Jian; Liu, Chang-Sheng; Yuan, Yuan; Tao, Xin-Yi; Shan, Xiao-Qian; Sheng, Yan; Wu, Fan

    2007-03-01

    Hb (hemoglobin)-loaded particles (HbP) encapsulated by a biodegradable polymer used as oxygen carrier were prepared. A modified double emulsion and solvent diffusion/evaporation method was adopted. All experiments were performed based on two types of biodegradable polymers, poly(epsilon-caprolactone) (PCL) and poly(epsilon-caprolactone-ethylene glycol) (PCL-PEG). The biodistribution and the survival time in blood of the particles were investigated in a mouse model. Encapsulation efficiency and pore-connecting efficiency were evaluated by a novel sulfocyanate potassium method. The influence of process parameters on the particle size and pore-connecting efficiency (PCE%) of nanoparticles have been discussed. The prepared conditions: solvent, external aqueous phase, pressure were discussed. The system utilizing dichloromethane (DCM)/ethyl acetate (EA) as a solvent with an unsaturated external aqueous phase yielded the highest encapsulation efficiency (87.35%) with a small mean particle size (153 nm). The formation of porous channels was attributed to the diffusion of solvent. The PCE% was more sensitive to the rate of solvent diffusion that was obviously affected by the preparation temperature. The PCE% reached 87.47% when PCL-PEG was employed at 25 degrees C. P(50) of HbP was 27 mmHg, which does not seem to be greatly affected by the encapsulation procedure. In vivo, following intravenous injection of 6-coumarin labeled HbP, the major organ accumulating Hb-loaded particles was the liver. The half-life of nano-sized PCL HbP was 3.1 times as long as the micro-sized PCL HbP. Also, Nano-sized as well as a PEGylated surface on HbP is beneficial for prolonged blood residence (7.2 fold increase).

  19. 40 CFR 766.38 - Reporting on precursor chemical substances.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Reporting on precursor chemical... SUBSTANCES CONTROL ACT DIBENZO-PARA-DIOXINS/DIBENZOFURANS Specific Chemical Testing/Reporting Requirements § 766.38 Reporting on precursor chemical substances. (a) Identification of precursor chemical substances...

  20. 40 CFR 766.38 - Reporting on precursor chemical substances.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Reporting on precursor chemical... SUBSTANCES CONTROL ACT DIBENZO-PARA-DIOXINS/DIBENZOFURANS Specific Chemical Testing/Reporting Requirements § 766.38 Reporting on precursor chemical substances. (a) Identification of precursor chemical substances...

  1. 40 CFR 766.38 - Reporting on precursor chemical substances.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Reporting on precursor chemical... SUBSTANCES CONTROL ACT DIBENZO-PARA-DIOXINS/DIBENZOFURANS Specific Chemical Testing/Reporting Requirements § 766.38 Reporting on precursor chemical substances. (a) Identification of precursor chemical substances...

  2. 40 CFR 766.38 - Reporting on precursor chemical substances.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Reporting on precursor chemical... SUBSTANCES CONTROL ACT DIBENZO-PARA-DIOXINS/DIBENZOFURANS Specific Chemical Testing/Reporting Requirements § 766.38 Reporting on precursor chemical substances. (a) Identification of precursor chemical substances...

  3. 40 CFR 766.38 - Reporting on precursor chemical substances.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Reporting on precursor chemical... SUBSTANCES CONTROL ACT DIBENZO-PARA-DIOXINS/DIBENZOFURANS Specific Chemical Testing/Reporting Requirements § 766.38 Reporting on precursor chemical substances. (a) Identification of precursor chemical substances...

  4. Shape-programmed nanofabrication: understanding the reactivity of dichalcogenide precursors.

    PubMed

    Guo, Yijun; Alvarado, Samuel R; Barclay, Joshua D; Vela, Javier

    2013-04-23

    Dialkyl and diaryl dichalcogenides are highly versatile and modular precursors for the synthesis of colloidal chalcogenide nanocrystals. We have used a series of commercially available dichalcogenide precursors to unveil the molecular basis for the outcome of nanocrystal preparations, more specifically, how precursor molecular structure and reactivity affect the final shape and size of II-VI semiconductor nanocrystals. Dichalcogenide precursors used were diallyl, dibenzyl, di-tert-butyl, diisopropyl, diethyl, dimethyl, and diphenyl disulfides and diethyl, dimethyl, and diphenyl diselenides. We find that the presence of two distinctively reactive C-E and E-E bonds makes the chemistry of these precursors much richer and interesting than that of other conventional precursors such as the more common phosphine chalcogenides. Computational studies (DFT) reveal that the dissociation energy of carbon-chalcogen (C-E) bonds in dichalcogenide precursors (R-E-E-R, E=S or Se) increases in the order (R): diallylprecursor reactivity, leading to progressively slower nucleation and higher selectivity for anisotropic growth, all the way from dots to pods to tetrapods. Under identical experimental conditions, we obtain CdS and CdSe nanocrystals with spherical, elongated, or tetrapodal morphology by simply varying the identity and reactivity of the dichalcogenide precursor. Interestingly, we find that precursors with strong C-E and weak E-E bond dissociation energies such as Ph-S-S-Ph serve as a ready source of thiol radicals that appear to stabilize small CdE nuclei, facilitating anisotropic growth. These CdS and CdSe nanocrystals have been

  5. Mechanical mixtures of metal oxides and phosphorus pentoxide as novel precursors for the synthesis of transition-metal phosphides.

    PubMed

    Guo, Lijuan; Zhao, Yu; Yao, Zhiwei

    2016-01-21

    This study presents a new type of precursor, mechanical mixtures of metal oxides (MOs) and phosphorus pentoxide (P2O5) are used to synthesize Ni2P, Co2P and MoP phosphides by the H2 reduction method. In addition, this is first report of common solid-state P2O5 being used as a P source for the synthesis of metal phosphides. The traditional precursors are usually prepared via a complicated preparation procedure involving dissolution, drying and calcination steps. However, these novel MOs/P2O5 precursors can be obtained only by simple mechanical mixing of the starting materials. Furthermore, unlike the direct transformation from amorphous phases to phosphides, various specific intermediates were involved in the transformation from MOs/P2O5 to phosphides. It is worthy to note that the dispersions of Ni2P, Co2P and MoP obtained from MOs/P2O5 precursors were superior to those of the corresponding phosphides prepared from the abovementioned traditional precursors. It is suggested that the morphology of the as-prepared metal phosphides might be inherited from the corresponding MOs. Based on the results of XRD, XPS, SEM and TEM, the formation pathway of phosphides can be defined as MOs/P2O5 precursors → complex intermediates (metals, metal phosphates and metal oxide-phosphates) → metal phosphides.

  6. New Polymeric Precursors of Silicon Carbide

    NASA Technical Reports Server (NTRS)

    Litt, M.; Kumar, K.

    1987-01-01

    Silicon carbide made by pyrolizing polymers. Method conceived for preparation of poly(decamethylcyclohexasilanes) as precursors for preparation of silicon carbide at high yield. Technical potential of polysilanes as precursors of SiC ceramics being explored. Potential limited by intractability of some polysilanes; formation of small, cyclic polycarbosilane fragments during pyrolysis; and overall low char yield and large shrinkage in conversion to ceramics.

  7. Synthesis and electrochemical performances of amorphous carbon-coated Sn Sb particles as anode material for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Wang, Zhong; Tian, Wenhuai; Liu, Xiaohe; Yang, Rong; Li, Xingguo

    2007-12-01

    The amorphous carbon coating on the Sn-Sb particles was prepared from aqueous glucose solutions using a hydrothermal method. Because the outer layer carbon of composite materials is loose cotton-like and porous-like, it can accommodate the expansion and contraction of active materials to maintain the stability of the structure, and hinder effectively the aggregation of nano-sized alloy particles. The as-prepared composite materials show much improved electrochemical performances as anode materials for lithium-ion batteries compared with Sn-Sb alloy and carbon alone. This amorphous carbon-coated Sn-Sb particle is extremely promising anode materials for lithium secondary batteries and has a high potentiality in the future use.

  8. Method for forming solar cell materials from particulars

    DOEpatents

    Eberspacher, Chris; Pauls, Karen Lea

    2001-01-01

    Materials in bulk and film forms are prepared from fine particulate precursors such as single-phase, mixed-metal oxides; multi-phase, mixed-metal particles comprising a metal oxide; multinary metal particles; mixtures of such particles with other particles; and particulate materials intercalated with other materials.

  9. Effects of micro-sized and nano-sized WO3 on mass attenauation coefficients of concrete by using MCNPX code.

    PubMed

    Tekin, H O; Singh, V P; Manici, T

    2017-03-01

    In the present work the effect of tungsten oxide (WO 3 ) nanoparticles on mass attenauation coefficients of concrete has been investigated by using MCNPX (version 2.4.0). The validation of generated MCNPX simulation geometry has been provided by comparing the results with standard XCOM data for mass attenuation coefficients of concrete. A very good agreement between XCOM and MCNPX have been obtained. The validated geometry has been used for definition of nano-WO 3 and micro-WO 3 into concrete sample. The mass attenuation coefficients of pure concrete and WO 3 added concrete with micro-sized and nano-sized have been compared. It was observed that shielding properties of concrete doped with WO 3 increased. The results of mass attenauation coefficients also showed that the concrete doped with nano-WO 3 significanlty improve shielding properties than micro-WO 3 . It can be concluded that addition of nano-sized particles can be considered as another mechanism to reduce radiation dose. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Effects of detergents on ribosomal precursor subunits of Bacillus megaterium.

    PubMed

    Body, A; Brownstein, B H

    1978-01-01

    Cell extracts prepared by osmotic lysis of protoplasts were analyzed by sucrose gradient sedimentation. In the absence of detergents, ribosomal precursor particles were found in a gradient fraction which sedimented faster than mature 50S subunits and in two other fractions coincident with mature 50S and 30S ribosomal subunits. Phospholipid, an indicator of membrane, was shown to be associated with only the fastest-sedimenting ribosomal precursor particle fraction. After the extracts were treated with detergents, all phospholipid was found at the top of the gradients. Brij 58, Triton X-100, and Nonidet P-40 did not cause a change in the sedimentation values of precursors; however, the detergents deoxycholate or LOC (Amway Corp.) disrupted the fastest-sedimenting precursor and converted the ribosomal precursor subunits which sedimented at the 50S and 30S positions to five different classes of more slowly sedimenting particles. Earlier reports on the in vivo assembly of ribosomal subunits have shown that several stages of ribosomal precursor subunits exist, and, in the presence of the detergents deoxycholate and LOC, which had been used to prepare cell extracts, the precursors sedimented more slowly. Our data are consistent with the hypothesis that those detergents selectively modify the structure of ribosomal precursors and lend further support to the hypothesis that the in vivo ribosomal precursor subunits have 50S and 30S sedimentation values. In addition, these data support the idea that the ribosomal precursor particles found in the fast-sedimenting fraction may constitute a unique precursor fraction.

  11. Effects of Detergents on Ribosomal Precursor Subunits of Bacillus megaterium

    PubMed Central

    Body, Barbara A.; Brownstein, Bernard H.

    1978-01-01

    Cell extracts prepared by osmotic lysis of protoplasts were analyzed by sucrose gradient sedimentation. In the absence of detergents, ribosomal precursor particles were found in a gradient fraction which sedimented faster than mature 50S subunits and in two other fractions coincident with mature 50S and 30S ribosomal subunits. Phospholipid, an indicator of membrane, was shown to be associated with only the fastest-sedimenting ribosomal precursor particle fraction. After the extracts were treated with detergents, all phospholipid was found at the top of the gradients. Brij 58, Triton X-100, and Nonidet P-40 did not cause a change in the sedimentation values of precursors; however, the detergents deoxycholate or LOC (Amway Corp.) disrupted the fastest-sedimenting precursor and converted the ribosomal precursor subunits which sedimented at the 50S and 30S positions to five different classes of more slowly sedimenting particles. Earlier reports on the in vivo assembly of ribosomal subunits have shown that several stages of ribosomal precursor subunits exist, and, in the presence of the detergents deoxycholate and LOC, which had been used to prepare cell extracts, the precursors sedimented more slowly. Our data are consistent with the hypothesis that those detergents selectively modify the structure of ribosomal precursors and lend further support to the hypothesis that the in vivo ribosomal precursor subunits have 50S and 30S sedimentation values. In addition, these data support the idea that the ribosomal precursor particles found in the fast-sedimenting fraction may constitute a unique precursor fraction. PMID:412833

  12. Nanosized graphene sheets enhanced photoelectric behavior of carbon film on p-silicon substrate

    NASA Astrophysics Data System (ADS)

    Yang, Lei; Hu, Gaijuan; Zhang, Dongqing; Diao, Dongfeng

    2016-07-01

    We found that nanosized graphene sheets enhanced the photoelectric behavior of graphene sheets embedded carbon (GSEC) film on p-silicon substrate, which was deposited under low energy electron irradiation in electron cyclotron resonance plasma. The GSEC/p-Si photodiode exhibited good photoelectric performance with photoresponsivity of 206 mA/W, rise and fall time of 2.2, and 4.3 μs for near-infrared (850 nm) light. The origin of the strong photoelectric behavior of GSEC film was ascribed to the appearance of graphene nanosheets, which led to higher barrier height and photoexcited electron-collection efficiency. This finding indicates that GSEC film has the potential for photoelectric applications.

  13. High Temperature Oxidation of Nickel-based Cermet Coatings Composed of Al2O3 and TiO2 Nanosized Particles

    NASA Astrophysics Data System (ADS)

    Farrokhzad, M. A.; Khan, T. I.

    2014-09-01

    New technological challenges in oil production require materials that can resist high temperature oxidation. In-Situ Combustion (ISC) oil production technique is a new method that uses injection of air and ignition techniques to reduce the viscosity of bitumen in a reservoir and as a result crude bitumen can be produced and extracted from the reservoir. During the in-situ combustion process, production pipes and other mechanical components can be exposed to air-like gaseous environments at extreme temperatures as high as 700 °C. To protect or reduce the surface degradation of pipes and mechanical components used in in-situ combustion, the use of nickel-based ceramic-metallic (cermet) coating produced by co-electrodeposition of nanosized Al2O3 and TiO2 have been suggested and earlier research on these coatings have shown promising oxidation resistance against atmospheric oxygen and combustion gases at elevated temperatures. Co-electrodeposition of nickel-based cermet coatings is a low-cost method that has the benefit of allowing both internal and external surfaces of pipes and components to be coated during a single electroplating process. Research has shown that the volume fraction of dispersed nanosized Al2O3 and TiO2 particles in the nickel matrix which affects the oxidation resistance of the coating can be controlled by the concentration of these particles in the electrolyte solution, as well as the applied current density during electrodeposition. This paper investigates the high temperature oxidation behaviour of novel nanostructured cermet coatings composed of two types of dispersed nanosized ceramic particles (Al2O3 and TiO2) in a nickel matrix and produced by coelectrodeposition technique as a function of the concentration of these particles in the electrolyte solution and applied current density. For this purpose, high temperature oxidation tests were conducted in dry air for 96 hours at 700 °C to obtain mass changes (per unit of area) at specific time

  14. Nanostructuring superconductors by ion beams: A path towards materials engineering

    NASA Astrophysics Data System (ADS)

    Gerbaldo, Roberto; Ghigo, Gianluca; Gozzelino, Laura; Laviano, Francesco; Amato, Antonino; Rovelli, Alberto; Cherubini, Roberto

    2013-07-01

    The paper deals with nanostructuring of superconducting materials by means of swift heavy ion beams. The aim is to modify their structural, optical and electromagnetic properties in a controlled way, to provide possibility of making them functional for specific applications. Results are presented concerning flux pinning effects (implantation of columnar defects with nanosize cross section to enhance critical currents and irreversibility fields), confined flux-flow and vortex guidance, design of devices by locally tailoring the superconducting material properties, analysis of disorder-induced effects in multi-band superconductors. These studies were carried out on different kinds of superconducting samples, from single crystals to thin films, from superconducting oxides to magnesium diboride, to recently discovered iron-based superconductors.

  15. A systematic review of methamphetamine precursor regulations.

    PubMed

    McKetin, Rebecca; Sutherland, Rachel; Bright, David A; Norberg, Melissa M

    2011-11-01

    To assess the effectiveness of methamphetamine precursor regulations in reducing illicit methamphetamine supply and use. A systematic review of 12 databases was used to identify studies that had evaluated the impact of methamphetamine precursor regulations on methamphetamine supply and/or use. The guidelines of the Effective Practice and Organization of Care Group (EPOC) of The Cochrane Collaboration were used to determine which study designs were included and assess their quality. Ten studies met the inclusion criteria. These studies evaluated 15 interventions (13 regulations and two related interdiction efforts), all of which were located in North America. Interventions had consistent impacts across various indicators of methamphetamine supply and use. Seven of the 15 interventions produced reductions in methamphetamine indicators (ranging from 12% to 77%). Two of the largest impacts were seen following interdiction efforts, involving the closure of rogue pharmaceutical companies. There was no evidence of a shift into other types of drug use, or injecting use, although the impact on the synthetic drug market was not examined. Null effects were related largely to the existence of alternative sources of precursor chemicals or the availability of imported methamphetamine. Methamphetamine precursor regulations can reduce indicators of methamphetamine supply and use. Further research is needed to determine whether regulations can be effective outside North America, particularly in developing countries, and what impact they have on the broader synthetic drug market. Improved data on precursor diversion are needed to facilitate the evaluation of precursor regulations. © 2011 The Authors, Addiction © 2011 Society for the Study of Addiction.

  16. The Interrelationships of Mathematical Precursors in Kindergarten

    ERIC Educational Resources Information Center

    Cirino, Paul T.

    2011-01-01

    This study evaluated the interrelations among cognitive precursors across quantitative, linguistic, and spatial attention domains that have been implicated for math achievement in young children. The dimensionality of the quantity precursors was evaluated in 286 kindergarteners via latent variable techniques, and the contribution of precursors…

  17. Multilayer Electroactive Polymer Composite Material Comprising Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Ounaies, Zoubeida (Inventor); Park, Cheol (Inventor); Harrison, Joycelyn S. (Inventor); Holloway, Nancy M. (Inventor); Draughon, Gregory K. (Inventor)

    2009-01-01

    An electroactive material comprises multiple layers of electroactive composite with each layer having unique dielectric, electrical and mechanical properties that define an electromechanical operation thereof when affected by an external stimulus. For example, each layer can be (i) a 2-phase composite made from a polymer with polarizable moieties and an effective amount of carbon nanotubes incorporated in the polymer for a predetermined electromechanical operation, or (ii) a 3-phase composite having the elements of the 2-phase composite and further including a third component of micro-sized to nano-sized particles of an electroactive ceramic incorporated in the polymer matrix.

  18. Ferromagnetic effects for nanofluid venture through composite permeable stenosed arteries with different nanosize particles

    NASA Astrophysics Data System (ADS)

    Akbar, Noreen Sher; Mustafa, M. T.

    2015-07-01

    In the present article ferromagnetic field effects for copper nanoparticles for blood flow through composite permeable stenosed arteries is discussed. The copper nanoparticles for the blood flow with water as base fluid with different nanosize particles is not explored upto yet. The equations for the Cu-water nanofluid are developed first time in literature and simplified using long wavelength and low Reynolds number assumptions. Exact solutions have been evaluated for velocity, pressure gradient, the solid volume fraction of the nanoparticles and temperature profile. Effect of various flow parameters on the flow and heat transfer characteristics are utilized.

  19. Synthesis and Characterization of Chalcopyrite (CuInS2 and CuhInSe2) Colloidal Nanoparticles for Optoelectronic Applications via Low-Temperature Pyrolysis of Single-Source Precursors

    NASA Technical Reports Server (NTRS)

    Castro, S. L.; Bailey, S. G.; Raffaelle, R. P.; Banger, K. K.; Fahey, Stephen; Hepp, A. F.

    2003-01-01

    Nanocrystalline (or quantum dot) materials hold potential as components of next-generation photovoltaic (PV) devices. The inclusion of quantum dots in PV devices has been proposed as a means to improve the efficiency of photon conversion (quantum dot solar cell), enable low-cost deposition of thin-films, provide sites for exciton dissociation, and pathways for electron transport. Quantum dots are also expected to be more resistant to degradation from electron, proton, and alpha particle radiation than the corresponding bulk material, a requirement for use in space solar sells. Chalcopyrite nanocrystals can be produced by low-temperature thermal decomposition of single-source precursors such as (PR3)2CuIn(ER')4 (R = Ph, R' = Et, E = S; R = R' = Ph, E = Se). Single-source precursors are molecules which contain all the necessary elements for synthesis of a desired material. Thermal decomposition of the precursor results in the formation of material with the correct stoichiometry as a nanocrystalline powder or a thin film, often at significantly lower temperatures than those typically employed for thin-film deposition by multi-source evaporation techniques, typically less than 500 C. We show that CuInSz and CuInSe2 nanocrystals can be synthesized from the precursors at temperatures as low as 250 C. The nanocrystals are characterized by optical spectroscopy, X-ray diffraction, and electron microscopy.

  20. Characterization of Nanoporous Materials with Atom Probe Tomography.

    PubMed

    Pfeiffer, Björn; Erichsen, Torben; Epler, Eike; Volkert, Cynthia A; Trompenaars, Piet; Nowak, Carsten

    2015-06-01

    A method to characterize open-cell nanoporous materials with atom probe tomography (APT) has been developed. For this, open-cell nanoporous gold with pore diameters of around 50 nm was used as a model system, and filled by electron beam-induced deposition (EBID) to obtain a compact material. Two different EBID precursors were successfully tested-dicobalt octacarbonyl [Co2(CO)8] and diiron nonacarbonyl [Fe2(CO)9]. Penetration and filling depth are sufficient for focused ion beam-based APT sample preparation. With this approach, stable APT analysis of the nanoporous material can be performed. Reconstruction reveals the composition of the deposited precursor and the nanoporous material, as well as chemical information of the interfaces between them. Thus, it is shown that, using an appropriate EBID process, local chemical information in three dimensions with sub-nanometer resolution can be obtained from nanoporous materials using APT.

  1. On the dielectric dispersion and absorption in nanosized manganese zinc mixed ferrites.

    PubMed

    Veena Gopalan, E; Malini, K A; Sakthi Kumar, D; Yoshida, Yasuhiko; Al-Omari, I A; Saravanan, S; Anantharaman, M R

    2009-04-08

    The temperature and frequency dependence of dielectric permittivity and dielectric loss of nanosized Mn(1-x)Zn(x)Fe(2)O(4) (for x = 0, 0.2, 0.4, 0.6, 0.8, 1) were investigated. The impact of zinc substitution on the dielectric properties of the mixed ferrite is elucidated. Strong dielectric dispersion and broad relaxation were exhibited by Mn(1-x)Zn(x)Fe(2)O(4). The variation of dielectric relaxation time with temperature suggests the involvement of multiple relaxation processes. Cole-Cole plots were employed as an effective tool for studying the observed phenomenon. The activation energies were calculated from relaxation peaks and Cole-Cole plots and found to be consistent with each other and indicative of a polaron conduction.

  2. Proposed mechanisms for water oxidation by Photosystem II and nanosized manganese oxides.

    PubMed

    Najafpour, Mohamad Mahdi; Heidari, Sima; Balaghi, S Esmael; Hołyńska, Małgorzata; Sadr, Moayad Hossaini; Soltani, Behzad; Khatamian, Maasoumeh; Larkum, Anthony W; Allakhverdiev, Suleyman I

    2017-02-01

    Plants, algae and cyanobacteria capture sunlight, extracting electrons from H 2 O to reduce CO 2 into sugars while releasing O 2 in the oxygenic photosynthetic process. Because of the important role of water oxidation in artificial photosynthesis and many solar fuel systems, understanding the structure and function of this unique biological catalyst forms a requisite research field. Herein the structure of the water-oxidizing complex and its ligand environment are described with reference to the 1.9Å resolution X-ray-derived crystallographic model of the water-oxidizing complex from the cyanobacterium Thermosynechococcus vulcanus. Proposed mechanisms for water oxidation by Photosystem II and nanosized manganese oxides are also reviewed and discussed in the paper. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Focusing of light by polymer-dispersed liquid-crystal films with nanosized droplets

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Loiko, V. A., E-mail: loiko@dragon.bas-net.by; Konkolovich, A. V.

    2006-12-15

    An analysis is presented of polarization-independent electrically tunable light focusing by polymerdispersed liquid-crystal films with nanosized liquid-crystal droplets. Polymer-dispersed liquid-crystal films with axially symmetric distributions of liquid-crystal droplet concentration and layers with axially symmetric thickness profiles are considered. The paraxial, Rayleigh, and Rayleigh-Gans approximations, as well as the Foldy-Twersky equation, are used to examine the dependence of focal length on lens geometry, droplet size, concentration of nematic liquid-crystal droplets, and applied field. The tunable focusing ranges are evaluated for both lens types considered in the study. Dependence of the transmittance of polymer-dispersed liquid-crystal film on its characteristics is analyzed. Themore » results obtained are compared with those available from the literature.« less

  4. Persistence of perfluoroalkyl acid precursors in AFFF-impacted groundwater and soil.

    PubMed

    Houtz, Erika F; Higgins, Christopher P; Field, Jennifer A; Sedlak, David L

    2013-08-06

    Several classes of polyfluorinated chemicals that are potential precursors to the perfluorinated carboxylates and sulfonates are present in aqueous film-forming foams (AFFF). To assess the persistence of these AFFF-derived precursors, groundwater, soil, and aquifer solids were obtained in 2011 from an unlined firefighter training area at a U.S. Air Force Base where AFFF was regularly used between 1970 and 1990. To measure the total concentration of perfluorinated carboxylate and sulfonate precursors in archived AFFF formulations and AFFF-impacted environmental samples, a previously developed assay that uses hydroxyl radical to oxidize precursors to perfluorinated carboxylates was adapted for these media. This assay was employed along with direct measurement of 22 precursors found in AFFF and a suite of other poly- and perfluoroalkyl substances (PFASs). On a molar basis, precursors accounted for 41-100% of the total concentration of PFASs in archived AFFF formulations. In the training area, precursors measured by the oxidation assay accounted for an average of 23% and 28% of total PFASs (i.e., precursors and perfluorinated carboxylates and sulfonates) in groundwater and solids samples, respectively. One precursor in AFFF, perfluorohexane sulfonamide amine, was observed on several highly contaminated soil and aquifer solids samples, but no other precursors present in AFFF formulations were detected in any samples at this field site. Suspected intermediate transformation products of precursors in AFFF that were directly measured accounted for approximately half of the total precursor concentration in samples from the training site. The fraction of PFASs consisting of perfluorinated carboxylates and sulfonates was greater in groundwater and solid samples than in any archived AFFF formulations, suggesting that much of the mass of precursors released at the site was converted to perfluorinated carboxylates and sulfonates. The precursors that have persisted at this site

  5. Position Assignment and Oxidation State Recognition of Fe and Co Centers in Heterometallic Mixed-Valent Molecular Precursors for the Low-Temperature Preparation of Target Spinel Oxide Materials

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lieberman, Craig M.; Barry, Matthew C.; Wei, Zheng

    A series of mixed-valent, heterometallic (mixed-transition metal) diketonates that can be utilized as prospective volatile single-source precursors for the low-temperature preparation of M xM' 3–xO 4 spinel oxide materials is reported. Three iron–cobalt complexes with Fe/Co ratios of 1:1, 1:2, and 2:1 were synthesized by several methods using both solid-state and solution reactions. On the basis of nearly quantitative reaction yields, elemental analyses, and comparison of metal–oxygen bonds with those in homometallic analogues, heterometallic compounds were formulated as [Fe III(acac) 3][Co II(hfac) 2] (1), [Co II(hfac) 2][Fe III(acac) 3][Co II(hfac) 2] (2), and [Fe II(hfac) 2][Fe III(acac) 3][Co II(hfac) 2]more » (3). In the above heteroleptic complexes, the Lewis acidic, coordinatively unsaturated CoII/FeII centers chelated by two hexafluoroacetylacetonate (hfac) ligands maintain bridging interactions with oxygen atoms of acetylacetonate (acac) groups that chelate the neighboring Fe III metal ion. Preliminary assignment of Fe and Co positions/oxidation states in 1–3 drawn from X-ray structural investigation was corroborated by a number of complementary techniques. Single-crystal resonant synchrotron diffraction and neutron diffraction experiments unambiguously confirmed the location of Fe and Co sites in the molecules of dinuclear (1) and trinuclear (2) complexes, respectively. Direct analysis in real time mass spectrometry revealed the presence of Fe III- and Co II-based fragments in the gas phase upon evaporation of precursors 1 and 2 as well as of Fe III, Fe II, and Co II species for complex 3. Theoretical investigation of two possible “valent isomers”, [Fe III(acac) 3][Co II(hfac) 2] (1) and [Co III(acac) 3][Fe II(hfac) 2] (1'), provided an additional support for the metal site/oxidation state assignment giving a preference of 6.48 kcal/mol for the experimentally observed molecule 1. Magnetic susceptibility measurements data are in agreement

  6. Superhydrophobic Ceramic Coatings by Solution Precursor Plasma Spray

    PubMed Central

    Cai, Yuxuan; Coyle, Thomas W.; Azimi, Gisele; Mostaghimi, Javad

    2016-01-01

    This work presents a novel coating technique to manufacture ceramic superhydrophobic coatings rapidly and economically. A rare earth oxide (REO) was selected as the coating material due to its hydrophobic nature, chemical inertness, high temperature stability, and good mechanical properties, and deposited on stainless steel substrates by solution precursor plasma spray (SPPS). The effects of various spraying conditions including standoff distance, torch power, number of torch passes, types of solvent and plasma velocity were investigated. The as-sprayed coating demonstrated a hierarchically structured surface topography, which closely resembles superhydrophobic surfaces found in nature. The water contact angle on the SPPS superhydrophobic coating was up to 65% higher than on smooth REO surfaces. PMID:27091306

  7. Synthesis of nano-sized lithium cobalt oxide via a sol-gel method

    NASA Astrophysics Data System (ADS)

    Li, Guangfen; Zhang, Jing

    2012-07-01

    In this study, nano-structured LiCoO2 thin film were synthesized by coupling a sol-gel process with a spin-coating method using polyacrylic acid (PAA) as chelating agent. The optimized conditions for obtaining a better gel formulation and subsequent homogenous dense film were investigated by varying the calcination temperature, the molar mass of PAA, and the precursor's molar ratios of PAA, lithium, and cobalt ions. The gel films on the silicon substrate surfaces were deposited by multi-step spin-coating process for either increasing the density of the gel film or adjusting the quantity of PAA in the film. The gel film was calcined by an optimized two-step heating procedure in order to obtain regular nano-structured LiCoO2 materials. Both atomic force microscopy (AFM) and scanning electron microscopy (SEM) were utilized to analyze the crystalline and the morphology of the films, respectively.

  8. Preparation and characterization of uniform nanosized cephradine by combination of reactive precipitation and liquid anti-solvent precipitation under high gravity environment.

    PubMed

    Zhong, Jie; Shen, Zhigang; Yang, Yan; Chen, Jianfeng

    2005-09-14

    In this work, a novel direct method, which was combined with reactive precipitation and liquid anti-solvent precipitation under high gravity environment, had been developed to prepare nanosized cephradine with narrow particle size distribution. Compared with commercial crude cephradine, the prepared cephradine showed a significant decrease in particle size, a significant increase in the specific surface area and shorter dissolving time when used for injection. The characteristic particle size was between 200-400 nm. The specific surface area increased from 2.95 to 10.87 m2/g after micronization. When the amount of L-arginin decreased from 0.25 to 0.18 g, the mixture of nanosized cephradine and L-arginine could still dissolve in 1 min. The X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) analysis indicated that the physical characteristics and molecular states remained unchanged after the recrystallization process. This method had potential application in industrial fields because of its low cost, efficient processing and the ease of scaling-up.

  9. Ga[OSi(O(t)Bu)3]3·THF, a thermolytic molecular precursor for high surface area gallium-containing silica materials of controlled dispersion and stoichiometry.

    PubMed

    Dombrowski, James P; Johnson, Gregory R; Bell, Alexis T; Tilley, T Don

    2016-07-05

    The molecular precursor tris[(tri-tert-butoxy)siloxy]gallium, as the tetrahydrofuran adduct Ga[OSi(O(t)Bu)3]3·THF (), was synthesized via the salt metathesis reaction of gallium trichloride with NaOSi(O(t)Bu)3. This complex serves as a model for isolated gallium in a silica framework. Complex decomposes thermally in hydrocarbon solvent, eliminating isobutylene, water, and tert-butanol to generate high surface area gallium-containing silica at low temperatures. When thermal decomposition was performed in the presence of P-123 Pluronic as a templating agent the generated material displayed uniform vermicular pores. Textural mesoporosity was evident in untemplated material. Co-thermolysis of with HOSi(O(t)Bu)3 in the presence of P-123 Pluronic led to materials with Ga : Si ratios ranging from 1 : 3 to 1 : 50, denoted UCB1-GaSi3, UCB1-GaSi10, UCB1-GaSi20 and UCB1-GaSi50. After calcination at 500 °C these materials exhibited decreasing surface areas and broadening pore distributions with increasing silicon content, indicating a loss of template effects. The position and dispersion of the gallium in UCB1-GaSi materials was investigated using (71)Ga MAS-NMR, powder XRD, and STEM/EDS elemental mapping. The results indicate a high degree of gallium dispersion in all samples, with gallium oxide clusters or oligomers present at higher gallium content.

  10. Precursor Lesions of Urologic Malignancies.

    PubMed

    Khani, Francesca; Robinson, Brian D

    2017-12-01

    - Precursor lesions of urologic malignancies are established histopathologic entities, which are important not only to recognize for clinical purposes, but also to further investigate at the molecular level in order to gain a better understanding of the pathogenesis of these malignancies. - To provide a brief overview of precursor lesions to the most common malignancies that develop within the genitourinary tract with a focus on their clinical implications, histologic features, and molecular characteristics. - Literature review from PubMed, urologic pathology textbooks, and the 4th edition of the World Health Organization Classification of Tumours of the Urinary System and Male Genital Organs. All photomicrographs were taken from cases seen at Weill Cornell Medicine or from the authors' personal slide collections. - The clinical importance and histologic criteria are well established for the known precursor lesions of the most common malignancies throughout the genitourinary tract, but further investigation is warranted at the molecular level to better understand the pathogenesis of these lesions. Such investigation may lead to better risk stratification of patients and potentially novel treatments.

  11. Plasma methods of obtainment of multifunctional composite materials, dispersion-hardened by nanoparticles

    NASA Astrophysics Data System (ADS)

    Sizonenko, O. N.; Grigoryev, E. G.; Zaichenko, A. D.; Pristash, N. S.; Torpakov, A. S.; Lipyan, Ye V.; Tregub, V. A.; Zholnin, A. G.; Yudin, A. V.; Kovalenko, A. A.

    2016-04-01

    The new approach in developed plasma methods consists in that dispersionhardening additives (TiC, TiB2 in particular) are not mechanically added to powder mixture as additional component, as in conventional methods, but are instead synthesized during high voltage electric discharges (HVED) in disperse system “hydrocarbon liquid - powder” preservation of ultrafine structure is ensured due to use of spark plasma sintering (SPS) as a consolidation method. HVED in disperse system “hydrocarbon liquid - powder” due to impact of plasma discharge channel, electromagnetic fields, shock waves mechanical impact, hydro flows and volume microcavitation leads to synthesis of nanocarbon, metal powders dispersion and synthesis of micro- (from 10-6 to 10-7 m) and nanosized (from 10-7 to 10-9 m) composite powders of hardening phases. SPS is the passage of pulsed current (superposition of direct and alternating current) through powder with the simultaneous mechanical compressing. The formation of plasma is initiated in gaseous phase that fills gaps between particles. SPS allows targeted control of grain growth rate and thus allows obtainment of multifunctional composite materials dispersion hardened by nanoparticles. Processes of HVED synthesis of micro- and nanosized powders of new compositions from elemental metal powders and their mixtures with the subsequent application of high-speed SPS of obtained powders create conditions for increase of strength (by 10 - 20%), hardness and wear-resistance (by 30 - 60%) of obtained materials.

  12. Thermal Stability of Jet Fuels: Kinetics of Forming Deposit Precursors

    NASA Technical Reports Server (NTRS)

    Naegeli, David W.

    1997-01-01

    The focus of this study was on the autoxidation kinetics of deposit precursor formation in jet fuels. The objectives were: (1) to demonstrate that laser-induced fluorescence is a viable kinetic tool for measuring rates of deposit precursor formation in jet fuels; (2) to determine global rate expressions for the formation of thermal deposit precursors in jet fuels; and (3) to better understand the chemical mechanism of thermal stability. The fuels were isothermally stressed in small glass ampules in the 120 to 180 C range. Concentrations of deposit precursor, hydroperoxide and oxygen consumption were measured over time in the thermally stressed fuels. Deposit precursors were measured using laser-induced fluorescence (LIF), hydroperoxides using a spectrophotometric technique, and oxygen consumption by the pressure loss in the ampule. The expressions, I.P. = 1.278 x 10(exp -11)exp(28,517.9/RT) and R(sub dp) = 2.382 x 10(exp 17)exp(-34,369.2/RT) for the induction period, I.P. and rate of deposit precursor formation R(sub dp), were determined for Jet A fuel. The results of the study support a new theory of deposit formation in jet fuels, which suggest that acid catalyzed ionic reactions compete with free radical reactions to form deposit precursors. The results indicate that deposit precursors form only when aromatics are present in the fuel. Traces of sulfur reduce the rate of autoxidation but increase the yield of deposit precursor. Free radical chemistry is responsible for hydroperoxide formation and the oxidation of sulfur compounds to sulfonic acids. Phenols are then formed by the acid catalyzed decomposition of benzylic hydroperoxides, and deposit precursors are produced by the reaction of phenols with aldehydes, which forms a polymer similar to Bakelite. Deposit precursors appear to have a phenolic resin-like structure because the LIF spectra of the deposit precursors were similar to that of phenolic resin dissolved in TAM.

  13. An acetate precursor process for BSCCO (2223) thin films and coprecipitated powders

    NASA Technical Reports Server (NTRS)

    Haertling, Gene H.

    1992-01-01

    Since the discovery of high temperature superconducting oxides much attention has been paid to finding better and useful ways to take advantage of the special properties exhibited by these materials. One such process is the development of thin films for engineering applications. Another such process is the coprecipitation route to producing superconducting powders. An acetate precursor process for use in thin film fabrication and a chemical coprecipitation route to Bismuth based superconducting materials has been developed. Data obtained from the thin film process were inconclusive to date and require more study. The chemical coprecipitation method of producing bulk material is a viable method, and is preferred over the previously used solid state route. This method of powder production appears to be an excellent route to producing thin section tape cast material and screen printed devices, as it requires less calcines than the oxide route to produce quality powders.

  14. Experimental analysis of precursors to severe problem behavior.

    PubMed

    Fritz, Jennifer N; Iwata, Brian A; Hammond, Jennifer L; Bloom, Sarah E

    2013-01-01

    Some individuals engage in both mild and severe forms of problem behavior. Research has shown that when mild behaviors precede severe behaviors (i.e., the mild behaviors serve as precursors), they can (a) be maintained by the same source of reinforcement as severe behavior and (b) reduce rates of severe behavior observed during assessment. In Study 1, we developed an objective checklist to identify precursors via videotaped trials for 16 subjects who engaged in problem behavior and identified at least 1 precursor for every subject. In Study 2, we conducted separate functional analyses of precursor and severe problem behaviors for 8 subjects, and obtained correspondence between outcomes in 7 cases. In Study 3, we evaluated noncontingent reinforcement schedule thinning plus differential reinforcement of alternative behavior to reduce precursors, increase appropriate behavior, and maintain low rates of severe behavior during 3 treatment analyses for 2 subjects. Results showed that this treatment strategy was effective for behaviors maintained by positive and negative reinforcement. © Society for the Experimental Analysis of Behavior.

  15. Biomineralization of a Self-assembled, Soft-Matrix Precursor: Enamel

    NASA Astrophysics Data System (ADS)

    Snead, Malcolm L.

    2015-04-01

    Enamel is the bioceramic covering of teeth, a composite tissue composed of hierarchical organized hydroxyapatite crystallites fabricated by cells under physiologic pH and temperature. Enamel material properties resist wear and fracture to serve a lifetime of chewing. Understanding the cellular and molecular mechanisms for enamel formation may allow a biology-inspired approach to material fabrication based on self-assembling proteins that control form and function. A genetic understanding of human diseases exposes insight from nature's errors by exposing critical fabrication events that can be validated experimentally and duplicated in mice using genetic engineering to phenocopy the human disease so that it can be explored in detail. This approach led to an assessment of amelogenin protein self-assembly that, when altered, disrupts fabrication of the soft enamel protein matrix. A misassembled protein matrix precursor results in loss of cell-to-matrix contacts essential to fabrication and mineralization.

  16. A totally phosphine-free synthesis of metal telluride nanocrystals by employing alkylamides to replace alkylphosphines for preparing highly reactive tellurium precursors.

    PubMed

    Yao, Dong; Liu, Yi; Zhao, Wujun; Wei, Haotong; Luo, Xintao; Wu, Zhennan; Dong, Chunwei; Zhang, Hao; Yang, Bai

    2013-10-21

    Despite the developments in the wet chemical synthesis of high-quality semiconductor nanocrystals (NCs) with diverse elemental compositions, telluride NCs are still irreplaceable materials owing to their excellent photovoltaic and thermoelectric performances. Herein we demonstrate the dissolution of elemental tellurium (Te) in a series of alkylamides by sodium borohydride (NaBH4) reduction at relatively low temperature to produce highly reactive precursors for hot-injection synthesis of telluride NCs. The capability to tune the reactivity of Te precursors by selecting injection temperature permits control of NC size over a broad range. The current preparation of Te precursors is simple, economical, and totally phosphine-free, which will promote the commercial synthesis and applications of telluride NCs.

  17. Combining single source chemical vapour deposition precursors to explore the phase space of titanium oxynitride thin films.

    PubMed

    Rees, Kelly; Lorusso, Emanuela; Cosham, Samuel D; Kulak, Alexander N; Hyett, Geoffrey

    2018-02-14

    In this paper we report on a novel chemical vapour deposition approach to the formation and control of composition of mixed anion materials, as applied to titanium oxynitride thin films. The method used is the aerosol assisted chemical vapour deposition (AACVD) of a mixture of single source precursors. To explore the titanium-oxygen-nitrogen system the single source precursors selected were tetrakis(dimethylamido) titanium and titanium tetraisopropoxide which individually are precursors to thin films of titanium nitride and titanium dioxide respectively. However, by combining these precursors in specific ratios in a series of AACVD reactions at 400 °C, we are able to deposit thin films of titanium oxynitride with three different structure types and a wide range of compositions. Using this precursor system we can observe films of nitrogen doped anatase, with 25% anion doping of nitrogen; a new composition of pseudobrookite titanium oxynitride with a composition of Ti 3 O 3.5 N 1.5 , identified as being a UV photocatalyst; and rock-salt titanium oxynitride in the range TiO 0.41 N 0.59 to TiO 0.05 N 0.95 . The films were characterised using GIXRD, WDX and UV-vis spectroscopy, and in the case of the pseudobrookite films, assessed for photocatalytic activity. This work shows that a so-called dual single-source CVD approach is an effective method for the deposition of ternary mixed anion ceramic films through simple control of the ratio of the precursors, while keeping all other experimental parameters constant.

  18. Nanostructured MnO2 as Electrode Materials for Energy Storage

    PubMed Central

    Mauger, Alain

    2017-01-01

    Manganese dioxides, inorganic materials which have been used in industry for more than a century, now find great renewal of interest for storage and conversion of energy applications. In this review article, we report the properties of MnO2 nanomaterials with different morphologies. Techniques used for the synthesis, structural, physical properties, and electrochemical performances of periodic and aperiodic frameworks are discussed. The effect of the morphology of nanosized MnO2 particles on their fundamental features is evidenced. Applications as electrodes in lithium batteries and supercapacitors are examined. PMID:29149066

  19. Resistive Switching and Voltage Induced Modulation of Tunneling Magnetoresistance in Nanosized Perpendicular Organic Spin Valves

    NASA Astrophysics Data System (ADS)

    Schmidt, Georg; Goeckeritz, Robert; Homonnay, Nico; Mueller, Alexander; Fuhrmann, Bodo

    Resistive switching has already been reported in organic spin valves (OSV), however, its origin is still unclear. We have fabricated nanosized OSV based on La0.7Sr0.3MnO3/Alq3/Co. These devices show fully reversible resistive switching of up to five orders of magnitude. The magnetoresistance (MR) is modulated during the switching process from negative (-70%) to positive values (+23%). The results are reminiscent of experiments claiming magnetoelectric coupling in LSMO based tunneling structures using ferroelectric barriers. By analyzing the I/V characteristics of the devices we can show that transport is dominated by tunneling through pinholes. The resistive switching is caused by voltage induced creation and motion of oxygen vacancies at the LSMO surface, however, the resulting tunnel barrier is complemented by a second adjacent barrier in the organic semiconductor. Our model shows that the barrier in the organic material is constant, causing the initial MR while the barrier in the LMSO can be modulated by the voltage resulting in the resistive switching and the modulation of the MR as the coupling to the states in the LSMO changes. A switching caused by LSMO only is also supported by the fact that replacing ALQ3 by H2PC yields almost identical results. Supported by the DFG in the SFB762.

  20. Precursors of chicken flavor. II. Identification of key flavor precursors using sensory methods.

    PubMed

    Aliani, Michel; Farmer, Linda J

    2005-08-10

    Sensory evaluation was used to identify flavor precursors that are critical for flavor development in cooked chicken. Among the potential flavor precursors studied (thiamin, inosine 5'-monophosphate, ribose, ribose-5-phosphate, glucose, and glucose-6-phosphate), ribose appears most important for chicken aroma. An elevated concentration (added or natural) of only 2-4-fold the natural concentration gives an increase in the selected aroma and flavor attributes of cooked chicken meat. Assessment of the volatile odor compounds by gas chromatography-odor assessment and gas chromatography-mass spectrometry showed that ribose increased odors described as "roasted" and "chicken" and that the changes in odor due to additional ribose are probably caused by elevated concentrations of compounds such as 2-furanmethanethiol, 2-methyl-3-furanthiol, and 3-methylthiopropanal.

  1. Reactive Processing of Environmentally Conscious, Biomorphic Ceramics from Natural Wood Precursors

    NASA Technical Reports Server (NTRS)

    Singh, M.; Yee, Bo-Moon

    2003-01-01

    Environmentally conscious, biomorphic ceramics (Ecoceramics) are a new class of materials that are manufactured from renewable resources and wastes. In this study, silicon carbide and oxide-based biomorphic ceramics have been fabricated from pine and jelutong wood precursors. A carbonaceous preform is produced through wood pyrolysis and subsequent infiltration with oxides (ZrO2 sols) and liquid silicon to form ceramics. These biomorphic ceramics show a wide variety of microstructures, densities, and hardness behavior that are determined by the type of wood and infiltrants selected.

  2. Lanthanide-Substituted Magnetite Nanoparticles Using a New Mixed Precursor Method by Thermoanaerobacter ethanolicus

    NASA Astrophysics Data System (ADS)

    Moon, J.; Roh, Y.; Yeary, L. W.; Lauf, R. J.; Phelps, T. J.

    2006-12-01

    A metal reducing bacterium, Thermoanaerobacter ethanolicus successfully converted the precursor of L (lanthanide)-mixed akaganeite (LxFe1-xOOH) phase to L-substituted magnetite (LyFe3-yO4) while avoiding the potentially toxic effects of soluble L-ions. Antibiotic elements, lanthanide (Nd, Gd, Tb, Ho, and Er)-substituted magnetites were produced by microbial fermentation using LxFe1-xOOH, where x was up to 0.02 which is equivalent to 0.72 mM. Combining lanthanides into the akaganeite precursor phase mitigated some of the toxicity when compared to the traditional method by using pure akaganeite and the dissolved L-salt form. This new technique showed that an upper limit of L-concentrations between 0.02 and 0.1 mM might suppress bacterial activity. At the equivalent L-cation mole fraction, the traditional method increased the concentration of soluble toxic L ions in the final media. The precursor method enabled production of microbially synthesized L- substituted magnetite with an L-concentration 36-fold greater than could be obtained when the lanthanides were added as soluble salts. These results were confirmed by protein assay. The increase of L-concentration in the magnetite evidently manipulates its physical properties such as decreasing Curie temperature and decreasing saturation magnetism of L-substituted magnetite. This mixed precursor method can therefore be used to extend the application for nanofermentation and other bacterial synthesis fields where there is a need for economically low-energy consumable microbial production of nanoscale materials that should involve toxic or inhibitory elements to bacterial growth.

  3. Production of jet fuel precursor monoterpenoids from engineered Escherichia coli: Production of Jet Fuel Precursor Monoterpenoids

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mendez-Perez, Daniel; Alonso-Gutierrez, Jorge; Hu, Qijun

    Monoterpenes (C 10 isoprenoids) are the main components of essential oils and are possible precursors for many commodity chemicals and high energy density fuels. Monoterpenes are synthesized from geranyl diphosphate (GPP), which is also the precursor for the biosynthesis of farnesyl diphosphate (FPP). FPP biosynthesis diverts the carbon flux from monoterpene production to C 15 products and quinone biosynthesis. In this study, we tested a chromosomal mutation of Escherichia coli's native FPP synthase (IspA) to improve GPP availability for the production of monoterpenes using a heterologous mevalonate pathway. Monoterpene production at high levels required not only optimization of GPP productionmore » but also a basal level of FPP to maintain growth. The optimized strains produced two jet fuel precursor monoterpenoids 1,8-cineole and linalool at the titer of 653 mg/L and 505 mg/L, respectively, in batch cultures with 1% glucose. The engineered strains developed in this work provide useful resources for the production of high-value monoterpenes.« less

  4. Production of jet fuel precursor monoterpenoids from engineered Escherichia coli: Production of Jet Fuel Precursor Monoterpenoids

    DOE PAGES

    Mendez-Perez, Daniel; Alonso-Gutierrez, Jorge; Hu, Qijun; ...

    2017-05-18

    Monoterpenes (C 10 isoprenoids) are the main components of essential oils and are possible precursors for many commodity chemicals and high energy density fuels. Monoterpenes are synthesized from geranyl diphosphate (GPP), which is also the precursor for the biosynthesis of farnesyl diphosphate (FPP). FPP biosynthesis diverts the carbon flux from monoterpene production to C 15 products and quinone biosynthesis. In this study, we tested a chromosomal mutation of Escherichia coli's native FPP synthase (IspA) to improve GPP availability for the production of monoterpenes using a heterologous mevalonate pathway. Monoterpene production at high levels required not only optimization of GPP productionmore » but also a basal level of FPP to maintain growth. The optimized strains produced two jet fuel precursor monoterpenoids 1,8-cineole and linalool at the titer of 653 mg/L and 505 mg/L, respectively, in batch cultures with 1% glucose. The engineered strains developed in this work provide useful resources for the production of high-value monoterpenes.« less

  5. Using Converter Dust to Produce Low Cost Cementitious Composites by in situ Carbon Nanotube and Nanofiber Synthesis

    PubMed Central

    Ludvig, Péter; Calixto, José M.; Ladeira, Luiz O.; Gaspar, Ivan C.P.

    2011-01-01

    Carbon nanotubes (CNTs) and nanofibers (CNFs) were synthesized on clinker and silica fume particles in order to create a low cost cementitious nanostructured material. The synthesis was carried out by an in situ chemical vapor deposition (CVD) process using converter dust, an industrial byproduct, as iron precursor. The use of these materials reduces the cost, with the objective of application in large-scale nanostructured cement production. The resulting products were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA) and were found to be polydisperse in size and to have defective microstructure. Some enhancement in the mechanical behavior of cement mortars was observed due to the addition of these nano-size materials. The contribution of these CNTs/CNFs to the mechanical strength of mortar specimens is similar to that of high quality CNTs incorporated in mortars by physical mixture. PMID:28880007

  6. Systems and methods for detection of blowout precursors in combustors

    DOEpatents

    Lieuwen, Tim C.; Nair, Suraj

    2006-08-15

    The present invention comprises systems and methods for detecting flame blowout precursors in combustors. The blowout precursor detection system comprises a combustor, a pressure measuring device, and blowout precursor detection unit. A combustion controller may also be used to control combustor parameters. The methods of the present invention comprise receiving pressure data measured by an acoustic pressure measuring device, performing one or a combination of spectral analysis, statistical analysis, and wavelet analysis on received pressure data, and determining the existence of a blowout precursor based on such analyses. The spectral analysis, statistical analysis, and wavelet analysis further comprise their respective sub-methods to determine the existence of blowout precursors.

  7. Polyether ether ketone implants achieve increased bone fusion when coated with nano-sized hydroxyapatite: a histomorphometric study in rabbit bone

    PubMed Central

    Johansson, Pär; Jimbo, Ryo; Naito, Yoshihito; Kjellin, Per; Currie, Fredrik; Wennerberg, Ann

    2016-01-01

    Polyether ether ketone (PEEK) possesses excellent mechanical properties similar to those of human bone and is considered the best alternative material other than titanium for orthopedic spine and trauma implants. However, the deficient osteogenic properties and the bioinertness of PEEK limit its fields of application. The aim of this study was to limit these drawbacks by coating the surface of PEEK with nano-scaled hydroxyapatite (HA) minerals. In the study, the biological response to PEEK, with and without HA coating, was investigated. Twenty-four screw-like and apically perforated implants in the rabbit femur were histologically evaluated at 3 weeks and 12 weeks after surgery. Twelve of the 24 implants were HA coated (test), and the remaining 12 served as uncoated PEEK controls. At 3 weeks and 12 weeks, the mean bone–implant contact was higher for test compared to control (P<0.05). The bone area inside the threads was comparable in the two groups, but the perforating hole showed more bone area for the HA-coated implants at both healing points (P<0.01). With these results, we conclude that nano-sized HA coating on PEEK implants significantly improved the osteogenic properties, and in a clinical situation this material composition may serve as an implant where a rapid bone fusion is essential. PMID:27103801

  8. MOCVD of aluminium oxide films using aluminium β-diketonates as precursors

    NASA Astrophysics Data System (ADS)

    Devi, A.; Shivashankar, S. A.; Samuelson, A. G.

    2002-06-01

    Deposition of Al203 coatings by CVD is of importance because they are often used as abrading material in cemented carbide cutting tools. The conventionally used CVD process for Al203 involves the corrosive reactant AICl3. In this paper, we report on the thermal characterisation of the metalorganic precursors namely aluminium tris-tetramethyl-heptanedionate [ Al(thd)3] and aluminium tris-acetylacetonate [ Al(acac)3] and their application to the CVD of Al203 films. Crystalline A1203 films were deposited by MOCVD at low temperatures by the pyrolysis of Al(thd)3 and AI(acac)3. The films were deposited on a TiN-coated tungsten carbide (TiN/WC) and Si(100) substrates in the temperature range 500-1100 °C. The as-deposited films were characterised by x-ray diffraction, optical microscopy, scanning and transmission electron microscopy, Auger electron spectroscopy. The observed crystallinity of films grown at low temperatures, their microstructure, and composition may be interpreted in terms of a growth process that involves the melting of the metalorganic precursor on the hot growth surface.

  9. Redundancy and divergence in the amyloid precursor protein family.

    PubMed

    Shariati, S Ali M; De Strooper, Bart

    2013-06-27

    Gene duplication provides genetic material required for functional diversification. An interesting example is the amyloid precursor protein (APP) protein family. The APP gene family has experienced both expansion and contraction during evolution. The three mammalian members have been studied quite extensively in combined knock out models. The underlying assumption is that APP, amyloid precursor like protein 1 and 2 (APLP1, APLP2) are functionally redundant. This assumption is primarily supported by the similarities in biochemical processing of APP and APLPs and on the fact that the different APP genes appear to genetically interact at the level of the phenotype in combined knockout mice. However, unique features in each member of the APP family possibly contribute to specification of their function. In the current review, we discuss the evolution and the biology of the APP protein family with special attention to the distinct properties of each homologue. We propose that the functions of APP, APLP1 and APLP2 have diverged after duplication to contribute distinctly to different neuronal events. Our analysis reveals that APLP2 is significantly diverged from APP and APLP1. Copyright © 2013 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  10. Preparation of a nanosized as(2)o(3)/mn(0.5)zn(0.5)fe(2)o(4) complex and its anti-tumor effect on hepatocellular carcinoma cells.

    PubMed

    Zhang, Jia; Zhang, Dongsheng

    2009-01-01

    Manganese-zinc-ferrite nanoparticles (Mn(0.5)Zn(0.5)Fe(2)O(4), MZF-NPs) prepared by an improved co-precipitation method and were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy dispersive spectrometry (EDS). Then thermodynamic testing of various doses of MZF-NPs was performed in vitro. The cytotoxicity of the Mn(0.5)Zn(0.5)Fe(2)O(4) nanoparticles in vitro was tested by the MTT assay. A nanosized As(2)O(3)/Mn(0.5)Zn(0.5)Fe(2)O(4) complex was made by an impregnation process. The complex's shape, component, envelop rate and release rate of As(2)O(3) were measured by SEM, EDS and atom fluorescence spectrometry, respectively. The therapeutic effect of nanosized As(2)O(3)/Mn(0.5)Zn(0.5)Fe(2)O(4) complex combined with magnetic fluid hyperthermia (MFH) on human hepatocelluar cells were evaluated in vitro by an MTT assay and flow cytometry. The results indicated that Mn(0.5)Zn(0.5)Fe(2)O(4) and nanosized As(2)O(3)/Mn(0.5)Zn(0.5)Fe(2)O(4) complex were both prepared successfully. The Mn(0.5)Zn(0.5)Fe(2)O(4) nanoparticles had powerful absorption capabilities in a high-frequency alternating electromagnetic field, and had strong magnetic responsiveness. Moreover, Mn(0.5)Zn(0.5)Fe(2)O(4) didn't show cytotoxicity in vitro. The therapeutic result reveals that the nanosized As(2)O(3)/Mn(0.5)Zn(0.5)Fe(2)O(4) complex can significantly inhibit the growth of hepatoma carcinoma cells.

  11. Precursors and adjuncts of a lunar base

    NASA Technical Reports Server (NTRS)

    Burke, J. D.

    1988-01-01

    The automated, teleoperated, robotic and human-tended subsystems which will precede and accompany a lunar base program are discussed. The information about lunar conditions that can be provided by such precursors and adjuncts is addressed. The use of precursors and adjuncts for communications and navigation, for safety and survival, for lunar archives, and for entertainment and leisure is examined.

  12. Supramolecular Assembly of Single-Source Metal-Chalcogenide Nanocrystal Precursors.

    PubMed

    Smith, Stephanie C; Bryks, Whitney; Tao, Andrea R

    2018-05-28

    In this Feature Article, we discuss our recent work in the synthesis of novel supramolecular precursors for semiconductor nanocrystals. Metal chalcogenolates that adopt liquid crystalline phases are employed as single-source precursors that template the growth of shaped solid-state nanocrystals. Supramolecular assembly is programmed by both precursor chemical composition and molecular parameters such alkyl chain length, steric bulk, and the intercalation of halide ions. Here, we explore the various design principles that enable the rational synthesis of these single-source precursors, their liquid crystalline phases, and the various semiconductor nanocrystal products that can be generated by thermolysis, ranging from highly anisotropic two-dimensional nanosheets and nanodisks to spheres.

  13. The behavior of delaminations in composite materials - experimental results

    NASA Astrophysics Data System (ADS)

    Chermoshentseva, A. S.; Pokrovskiy, A. M.; Bokhoeva, L. A.

    2016-02-01

    Delamination is one of the most common failure modes of composite materials. It may occur as a consequence of imperfections in the production process or the effects of external factors during the operational life of the composite laminates, such as the impact by foreign objects. This paper presents the results of mechanical tests and the optimum degrees of filling the composite materials (CM) with hydrophobic powder (Tarkosil T-20) depending on the latter mass concentration. The results present test samples of the CM with the underlying interlayer defects. The samples were fabricated of twenty-ply pre-preg (fiberglass or carbon fiber). The industrial grade glass is T-25 (VM) specification 6-11-380-76. The composite materials have nanosized additives in structure. The volume concentration of nanopowders is varying from 0.1% to 0.5%. This kind of research has been done for the first time.

  14. Geoelectric precursors to strong earthquakes in China

    NASA Astrophysics Data System (ADS)

    Yulin, Zhao; Fuye, Qian

    1994-05-01

    The main results of searching for electrical precursors to strong earthquakes in China for the last 25 yr are presented. This comprises: the continuous twenty-year resistivity record before and after the great Tangshan earthquake of 1976; spatial and temporal variations in resistivity anomalies observed at more than 6 stations within 150 km of the Tangshan earthquake epicenter; the travel-time curve for the front of the resistivity precursor; and a method of intersection for predicting the epicenter location. These results reveal a number of interesting facts: (1) Resistivity measurements with accuracies of 0.5% or better for over 20 yr show that resistivity decreases of several percent, which began approximately 3 yr prior to the Tangshan earthquake, were larger than the background fluctuations and hence statistically significant. An outstanding example of an intermediate-term resistivity precursor is given. (2) The intermediate-term resistivity precursor decrease before Tangshan earthquake is such a pervasive phenomenon that the mean decrease, in percent, can be contoured on a map of the Beijing-Tianjin-Tangshan region. This shows the maximum decrease centered over the epicenter. (3) The anomalies in resistivity and self-potential, which began 2-0.5 months before the Tangshan main shock, had periods equal to that of the tidal waves M 2 and MS f, respectively, so that the associated anomalies can be identified as impending-earthquake precursors and a modal related to stress-displacement weakening is proposed.

  15. High-fraction brookite films from amorphous precursors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Haggerty, James E. S.; Schelhas, Laura T.; Kitchaev, Daniil A.

    2017-11-09

    Structure-specific synthesis processes are of key importance to the growth of polymorphic functional compounds such as TiO 2, where material properties strongly depend on structure as well as chemistry. The robust growth of the brookite polymorph of TiO 2, a promising photocatalyst, has been difficult in both powder and thin-film forms due to the disparity of reported synthesis techniques, their highly specific nature, and lack of mechanistic understanding. In this work, we report the growth of high-fraction (~95%) brookite thin films prepared by annealing amorphous titania precursor films deposited by pulsed laser deposition. We characterize the crystallization process, eliminating themore » previously suggested roles of substrate templating and Na helper ions in driving brookite formation. Instead, we link phase selection directly to film thickness, offering a novel, generalizable route to brookite growth that does not rely on the presence of extraneous elements or particular lattice-matched substrates. In addition to providing a new synthesis route to brookite thin films, our results take a step towards resolving the problem of phase selection in TiO 2 growth, contributing to the further development of this promising functional material.« less

  16. High-fraction brookite films from amorphous precursors.

    PubMed

    Haggerty, James E S; Schelhas, Laura T; Kitchaev, Daniil A; Mangum, John S; Garten, Lauren M; Sun, Wenhao; Stone, Kevin H; Perkins, John D; Toney, Michael F; Ceder, Gerbrand; Ginley, David S; Gorman, Brian P; Tate, Janet

    2017-11-09

    Structure-specific synthesis processes are of key importance to the growth of polymorphic functional compounds such as TiO 2 , where material properties strongly depend on structure as well as chemistry. The robust growth of the brookite polymorph of TiO 2 , a promising photocatalyst, has been difficult in both powder and thin-film forms due to the disparity of reported synthesis techniques, their highly specific nature, and lack of mechanistic understanding. In this work, we report the growth of high-fraction (~95%) brookite thin films prepared by annealing amorphous titania precursor films deposited by pulsed laser deposition. We characterize the crystallization process, eliminating the previously suggested roles of substrate templating and Na helper ions in driving brookite formation. Instead, we link phase selection directly to film thickness, offering a novel, generalizable route to brookite growth that does not rely on the presence of extraneous elements or particular lattice-matched substrates. In addition to providing a new synthesis route to brookite thin films, our results take a step towards resolving the problem of phase selection in TiO 2 growth, contributing to the further development of this promising functional material.

  17. Two-photon sensitized recording materials for multilayer optical disk

    NASA Astrophysics Data System (ADS)

    Akiba, M.; Goto-Takahashi, E.; Takizawa, H.; Sasaki, T.; Mochizuki, H.; Mikami, T.; Kitahara, T.

    2010-06-01

    Two types of novel two-photon sensitized recording material writable at 405 nm and 522nm were developed. The fluorescent dye generation type (F-type) material consists of at least two-photon absorption dye (TPAD) and fluorescent dye precursor (FDP), which is non-fluorescent before two-photon recording and fluorescent after two-photon recording due to fluorescent dye generation. The fluorescence quench type (Q-type) material, on the other hand, consists of at least TPAD, fluorescent dye (FD) and fluorescent quencher precursor (QP), which is fluorescent before two-photon recording and the fluorescence intensity is reduced after two-photon recording at the recorded spot due to fluorescent quencher generation. Both types of material showed quadratic dependency of recording light intensity at 522 and 405 nm. A twenty-layer two-photon recording media was fabricated with the Q-type material, and two-photon recording and onephoton fluorescent signal readout was successfully conducted.

  18. Large-scale self-assembly of uniform submicron silver sulfide material driven by precise pressure control

    NASA Astrophysics Data System (ADS)

    Qi, Juanjuan; Chen, Ke; Zhang, Shuhao; Yang, Yun; Guo, Lin; Yang, Shihe

    2017-03-01

    The controllable self-assembly of nanosized building blocks into larger specific structures can provide an efficient method of synthesizing novel materials with excellent properties. The self-assembly of nanocrystals by assisted means is becoming an extremely active area of research, because it provides a method of producing large-scale advanced functional materials with potential applications in the areas of energy, electronics, optics, and biologics. In this study, we applied an efficient strategy, namely, the use of ‘pressure control’ to the assembly of silver sulfide (Ag2S) nanospheres with a diameter of approximately 33 nm into large-scale, uniform Ag2S sub-microspheres with a size of about 0.33 μm. More importantly, this strategy realizes the online control of the overall reaction system, including the pressure, reaction time, and temperature, and could also be used to easily fabricate other functional materials on an industrial scale. Moreover, the thermodynamics and kinetics parameters for the thermal decomposition of silver diethyldithiocarbamate (Ag(DDTC)) are also investigated to explore the formation mechanism of the Ag2S nanosized building blocks which can be assembled into uniform sub-micron scale architecture. As a method of producing sub-micron Ag2S particles by means of the pressure-controlled self-assembly of nanoparticles, we foresee this strategy being an efficient and universally applicable option for constructing other new building blocks and assembling novel and large functional micromaterials on an industrial scale.

  19. The photoelectronic behaviors of MoO3-loaded ZrO2/carbon cluster nanocomposite materials

    NASA Astrophysics Data System (ADS)

    Matsui, H.; Ishiko, A.; Karuppuchamy, S.; Hassan, M. A.; Yoshihara, M.

    2012-03-01

    A novel nano-sized ZrO2/carbon cluster composite materials (Ic's) were successfully obtained by the calcination of ZrCl4/starch complexes I's under an argon atmosphere. Pt- and/or MoO3-loaded ZrO2/carbon clusters composite materials were also prepared by doping Pt and/or MoO3 particles on the surface of Ic's. The surface characterization of the composite materials was carried out using transmission electron microscopy (TEM). The TEM observation of the materials showed the presence of particles with the diameters of a few nanometers, possibly Pt particles, and of 50-100 nm, possibly MoO3 particles, in the matrix. Pt- and/or MoO3-loaded ZrO2/carbon cluster composite materials show the efficient photocatalytic activity under visible light irradiation.

  20. An efficient preparation of labelling precursor of [11C]L-deprenyl-D2 and automated radiosynthesis.

    PubMed

    Zirbesegger, Kevin; Buccino, Pablo; Kreimerman, Ingrid; Engler, Henry; Porcal, Williams; Savio, Eduardo

    2017-01-01

    The synthesis of [ 11 C]L-deprenyl-D 2 for imaging of astrocytosis with positron emission tomography (PET) in neurodegenerative diseases has been previously reported. [ 11 C]L-deprenyl-D 2 radiosynthesis requires a precursor, L-nordeprenyl-D 2 , which has been previously synthesized from L-amphetamine as starting material with low overall yields. Here, we present an efficient synthesis of L-nordeprenyl-D 2 organic precursor as free base and automated radiosynthesis of [ 11 C]L-deprenyl-D 2 for PET imaging of astrocytosis. The L-nordeprenyl-D 2 precursor was synthesized from the easily commercial available and cheap reagent L-phenylalanine in five steps. Next, N -alkylation of L-nordeprenyl-D 2 free base with [ 11 C]MeOTf was optimized using the automated commercial platform GE TRACERlab® FX C Pro. A simple and efficient synthesis of L-nordeprenyl-D 2 precursor of [ 11 C]L-deprenyl-D 2 as free base has been developed in five synthetic steps with an overall yield of 33%. The precursor as free base has been stable for 9 months stored at low temperature (-20 °C). The labelled product was obtained with 44 ± 13% ( n  = 12) (end of synthesis, decay corrected) radiochemical yield from [ 11 C]MeI after 35 min synthesis time. The radiochemical purity was over 99% in all cases and specific activity was (170 ± 116) GBq/μmol. A high-yield synthesis of [ 11 C]L-deprenyl-D 2 has been achieved with high purity and specific activity. L-nordeprenyl-D 2 precursor as free amine was applicable for automated production in a commercial synthesis module for preclinical and clinical application.

  1. Vortex assisted solid-phase extraction of lead(II) using orthorhombic nanosized Bi2WO6 as a sorbent.

    PubMed

    Baghban, Neda; Yilmaz, Erkan; Soylak, Mustafa

    2017-12-07

    Nanosized single crystal orthorhombic Bi 2 WO 6 was synthesized by a hydrothermal method and used as a sorbent for vortex assisted solid phase extraction of lead(II). The crystal and molecular structure of the sorbent was examined using XRD, Raman, SEM and SEM-EDX analysis. Various parameters affecting extraction efficiency were optimized by using multivariate design. The effect of diverse ions on the extraction also was studied. Lead was quantified by flame atomic absorption spectrometry (FAAS). The recoveries of lead(II) from spiked samples (at a typical spiking level of 200-400 ng·mL -1 ) are >95%. Other figures of merit includes (a) a detection limit of 6 ng·mL -1 , (b) a preconcentration factor of 50, (c) a relative standard deviation of 1.6%, and (d) and adsorption capacity of 6.6 mg·g -1 . The procedure was successfully applied to accurate determination of lead in (spiked) pomegranate and water samples. Graphical abstract Nanosized single crystal orthorhombic Bi 2 WO 6 was synthesized and characterized by a hydrothermal method and used as a sorbent for vortex assisted solid phase extraction of lead(II). The procedure was successfully applied to accurate determination of lead in (spiked) pomegranate and water samples.

  2. A high yield reverse micelle synthesis of catalysts and catalyst precursors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Linehan, J.C.; Matson, D.W.; Darab, J.G.

    1995-04-01

    Reverse micelles or water-in-oil microemulsions have been prepared using a mixed AOT/SDS surfactant to increase the stability of the microemulsion and thereby allow a high loading of particle-forming precursors in the aqueous cores. The Modified Reverse Micelles (MRM), as these new binary surfactant microemulsions are called, have proven useful for the laboratory-scale synthesis of nanoscale metals, metal oxides, metal sulfides, and mixed metal materials. The system allows control over the phase and size of the precipitated crystallites and is ideal for producing nanocrystalline powders and suspensions.

  3. Exposure to nano-size titanium dioxide causes oxidative damages in human mesothelial cells: The crystal form rather than size of particle contributes to cytotoxicity.

    PubMed

    Hattori, Kenji; Nakadate, Kazuhiko; Morii, Akane; Noguchi, Takumi; Ogasawara, Yuki; Ishii, Kazuyuki

    2017-10-14

    Exposure to nanoparticles such as carbon nanotubes has been shown to cause pleural mesothelioma similar to that caused by asbestos, and has become an environmental health issue. Not only is the percutaneous absorption of nano-size titanium dioxide particles frequently considered problematic, but the possibility of absorption into the body through the pulmonary route is also a concern. Nevertheless, there are few reports of nano-size titanium dioxide particles on respiratory organ exposure and dynamics or on the mechanism of toxicity. In this study, we focused on the morphology as well as the size of titanium dioxide particles. In comparing the effects between nano-size anatase and rutile titanium dioxide on human-derived pleural mesothelial cells, the anatase form was shown to be actively absorbed into cells, producing reactive oxygen species and causing oxidative damage to DNA. In contrast, we showed for the first time that the rutile form is not easily absorbed by cells and, therefore, does not cause oxidative DNA damage and is significantly less damaging to cells. These results suggest that with respect to the toxicity of titanium dioxide particles on human-derived mesothelial cells, the crystal form rather than the particle size has a greater effect on cellular absorption. Also, it was indicated that the difference in absorption is the primary cause of the difference in the toxicity against mesothelial cells. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Low-temperature liquid precursors of crystalline metal oxides assisted by heterogeneous photocatalysis.

    PubMed

    Bretos, Iñigo; Jiménez, Ricardo; Pérez-Mezcua, Dulce; Salazar, Norberto; Ricote, Jesús; Calzada, M Lourdes

    2015-04-24

    The photocatalytically assisted decomposition of liquid precursors of metal oxides incorporating TiO2 particles enables the preparation of functional layers from the ferroelectric Pb(Zr,Ti)O3 and multiferroic BiFeO3 perovskite systems at temperatures not exceeding 350 ºC. This enables direct deposition on flexible plastic, where the multifunctionality provided by these complex-oxide materials guarantees their potential use in next-generation flexible electronics. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Noncatalytic hydrogenation of decene-1 with hydrogen accumulated in a hybrid carbon nanostructure in nanosized membrane reactors

    NASA Astrophysics Data System (ADS)

    Soldatov, A. P.

    2014-08-01

    Studies on the creation of nanosized membrane reactors (NMRs) of a new generation with accumulated hydrogen and a regulated volume of reaction zone were continued at the next stage. Hydrogenation was performed in the pores of ceramic membranes with hydrogen preliminarily adsorbed in mono- and multilayered orientated carbon nanotubes with graphene walls (OCNTGs)—a new hybrid carbon nanostructure formed on the inner pore surface. Quantitative determination of hydrogen adsorption in OCNTGs was performed using TRUMEM ultrafiltration membranes with D av = 50 and 90 nm and showed that hydrogen adsorption was up to ˜1.5% of the mass of OCNTG. The instrumentation and procedure for noncatalytic hydrogenation of decene-1 at 250-350°C using hydrogen accumulated and stored in OCNTG were developed. The conversion of decene-1 into decane was ˜0.2-1.8% at hydrogenation temperatures of 250 and 350°C, respectively. The rate constants and activation energy of hydrogenation were determined. The latter was found to be 94.5 kJ/mol, which is much smaller than the values typical for noncatalytic hydrogenations and very close to the values characteristic for catalytic reactions. The quantitative distribution of the reacting compounds in each pore regarded as a nanosized membrane reactor was determined. The activity of hydrogen adsorbed in a 2D carbon nanostructure was evaluated. Possible mechanisms of noncatalytic hydrogenation were discussed.

  6. N-Nitrosodimethylamine (NDMA) and its precursors in water and wastewater: A review on formation and removal.

    PubMed

    Sgroi, Massimiliano; Vagliasindi, Federico G A; Snyder, Shane A; Roccaro, Paolo

    2018-01-01

    This review summarizes major findings over the last decade related to N-Nitrosodimethylamine (NDMA) in water and wastewater. In particular, the review is focused on the removal of NDMA and of its precursors by conventional and advanced water and wastewater treatment processes. New information regarding formation mechanisms and precursors are discussed as well. NDMA precursors are generally of anthropogenic origin and their main source in water have been recognized to be wastewater discharges. Chloramination is the most common process that results in formation of NDMA during water and wastewater treatment. However, ozonation of wastewater or highly contaminated surface water can also generate significant levels of NDMA. Thus, NDMA formation control and remediation has become of increasing interest, particularly during treatment of wastewater-impacted water and during potable reuse application. NDMA formation has also been associated with the use of quaternary amine-based coagulants and anion exchange resins. UV photolysis with UV fluence far higher than typical disinfection doses is generally considered the most efficient technology for NDMA mitigation. However, recent studies on the optimization of biological processes offer a potentially lower-energy solution. Options for NDMA control include attenuation of precursor materials through physical removal, biological treatment, and/or deactivation by application of oxidants. Nevertheless, NDMA precursor identification and removal can be challenging and additional research and optimization is needed. As municipal wastewater becomes increasingly used as a source water for drinking, NDMA formation and mitigation strategies will become increasingly more important. The following review provides a summary of the most recent information available. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. University of South Florida- Phase Change Materials (PCM)

    ScienceCinema

    Goswami, Yogi; Stefanakos, Lee

    2018-05-30

    USF is developing low-cost, high-temperature phase-change materials (PCMs) for use in thermal energy storage systems. Heat storage materials are critical to the energy storage process. In solar thermal storage systems, heat can be stored in these materials during the day and released at night--when the sun is not out--to drive a turbine and produce electricity. In nuclear storage systems, heat can be stored in these materials at night and released to produce electricity during daytime peak-demand hours. Most PCMs do not conduct heat very well. Using an innovative, electroless encapsulation technique, USF is enhancing the heat transfer capability of its PCMs. The inner walls of the capsules will be lined with a corrosion-resistant, high-infrared emissivity coating, and the absorptivity of the PCM will be controlled with the addition of nano-sized particles. USF's PCMs remain stable at temperatures from 600 to 1,000°C and can be used for solar thermal power storage, nuclear thermal power storage, and other applications.

  8. Incorporation of DNA and Protein Precursors into Macromolecules by Bacteria at −15oC

    PubMed Central

    Christner, Brent C.

    2002-01-01

    DNA and protein precursors were incorporated into trichloroacetic acid-precipitated material by bacterial cell suspensions during incubation for 50 to 100 days at −15oC. Incorporation did not occur at −70oC and was inhibited by antibiotics. The results demonstrate that bacteria can perform macromolecular synthesis under conditions that mimic entrapment in glacial ice. PMID:12450874

  9. Role of precursor crystal structure on electrochemical performance of carbide-derived carbon electrodes

    NASA Astrophysics Data System (ADS)

    Palazzo, Benjamin; Norris, Zach; Taylor, Greg; Yu, Lei; Lofland, Samuel; Hettinger, Jeffrey

    2015-03-01

    Binary carbides with hexagonal and cubic crystal structures have been synthesized by reactive magnetron sputtering of vanadium and other transition metals in acetylene or methane gas mixed with argon. The binary carbides are converted to carbide-derived carbon (CDC) films using chlorine gas in a post-deposition process in an external vacuum reaction furnace. Residual chlorine has been removed using an annealing step in a hydrogen atmosphere. The CDC materials have been characterized by x-ray diffraction, x-ray fluorescence, and scanning electron microscopy. The performance of the CDC materials in electrochemical device applications has been measured with the hexagonal phase precursor demonstrating a significantly higher specific capacitance in comparison to that of the cubic phase. We report these results and pore-size distributions of these and similar materials.

  10. Tribological properties of the babbit B83-based composite materials fabricated by powder metallurgy

    NASA Astrophysics Data System (ADS)

    Kalashnikov, I. E.; Bolotova, L. K.; Bykov, P. A.; Kobeleva, L. I.; Katin, I. V.; Mikheev, R. S.; Kobernik, N. V.

    2016-07-01

    Technological processes are developed to fabricate composite materials based on B83 babbit using hot pressing of a mixture of powders in the presence of a liquid phase. As a result, the structure of the matrix B83 alloy is dispersed, the morphology of intermetallic phases is changed, and reinforcing micro- and nanosized fillers are introduced and uniformly distributed in the matrix. The tribological properties of the synthesized materials are studied. The friction of the B83 babbit + 0.5 wt % MSR + 3 wt % SiC (MSR is modified schungite rock) composite material at high loads is characterized by an increase in the stability coefficient, and the wear resistance of the material increases by a factor of 1.8 as compared to the as-cast alloy at comparable friction coefficients.

  11. Observation of a Hydrodynamically Driven, Radiative Precursor Shock

    NASA Astrophysics Data System (ADS)

    Keiter, P. A.; Drake, R. P.; Perry, T. S.; Robey, H.; Remington, B. A.; Iglesias, C. A.; Turner, N.; Stone, J.; Knauer, J.

    2001-10-01

    Many astrophysical systems, such as supernova remnants and jets, produce radiative-precursor shock waves. In a radiative-precursor shock, radiation from the shock ionizes and heats the medium ahead of it. The simulation of such systems requires that one treat both the emission and the absorption of the radiation. An important goal of this effort is to produce an experiment that can be modeled by astrophysical codes without implementing laser absorption physics into an astrophysical code. We report here the first measurements of a radiative-precursor shock in such an experiment. The experimental design is based on a past experiment[1,2] that used the Nova laser facility to simulate young supernova remnants. The target consists of a 60 νm CH plastic plug followed by a 150 νm vacuum gap and 2 mm of SiO2 aerogel foam. For the experiment, the density of the components and the laser-irradiation conditions are chosen so that the driven shock will produce an observable radiative precursor. We observed the radiative-precursor by using absorption spectroscopy. By backlighting the silicate aerogel foam with a thulium backlighter, we were able to observe both the 1s-2p and 1s-3p lines. These observations will allow us to determine the temperature profile in the precursor. 1. R.P. Drake, et al, Phys. Rev. Lett. 81, 2068 (1998). 2. R.P. Drake, et al., Phys. Plasmas, 7, 2142 (2000) Work supported by the U.S. Department of Energy both directly and through the Lawrence Livermore National Laboratory

  12. 40 CFR 93.164 - Inter-precursor mitigation measures and offsets.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 20 2011-07-01 2011-07-01 false Inter-precursor mitigation measures... § 93.164 Inter-precursor mitigation measures and offsets. Federal agencies must reduce the same type of... mitigation measures of different precursors of the same criteria pollutant, if such trades are allowed by a...

  13. 40 CFR 93.164 - Inter-precursor mitigation measures and offsets.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Inter-precursor mitigation measures... § 93.164 Inter-precursor mitigation measures and offsets. Federal agencies must reduce the same type of... mitigation measures of different precursors of the same criteria pollutant, if such trades are allowed by a...

  14. 40 CFR 93.164 - Inter-precursor mitigation measures and offsets.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 21 2012-07-01 2012-07-01 false Inter-precursor mitigation measures... § 93.164 Inter-precursor mitigation measures and offsets. Federal agencies must reduce the same type of... mitigation measures of different precursors of the same criteria pollutant, if such trades are allowed by a...

  15. 40 CFR 93.164 - Inter-precursor mitigation measures and offsets.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 21 2013-07-01 2013-07-01 false Inter-precursor mitigation measures... § 93.164 Inter-precursor mitigation measures and offsets. Federal agencies must reduce the same type of... mitigation measures of different precursors of the same criteria pollutant, if such trades are allowed by a...

  16. Predicting Solar Cycle 24 Using a Geomagnetic Precursor Pair

    NASA Technical Reports Server (NTRS)

    Pesnell, W. Dean

    2014-01-01

    We describe using Ap and F(10.7) as a geomagnetic-precursor pair to predict the amplitude of Solar Cycle 24. The precursor is created by using F(10.7) to remove the direct solar-activity component of Ap. Four peaks are seen in the precursor function during the decline of Solar Cycle 23. A recurrence index that is generated by a local correlation of Ap is then used to determine which peak is the correct precursor. The earliest peak is the most prominent but coincides with high levels of non-recurrent solar activity associated with the intense solar activity of October and November 2003. The second and third peaks coincide with some recurrent activity on the Sun and show that a weak cycle precursor closely following a period of strong solar activity may be difficult to resolve. A fourth peak, which appears in early 2008 and has recurrent activity similar to precursors of earlier solar cycles, appears to be the "true" precursor peak for Solar Cycle 24 and predicts the smallest amplitude for Solar Cycle 24. To determine the timing of peak activity it is noted that the average time between the precursor peak and the following maximum is approximately equal to 6.4 years. Hence, Solar Cycle 24 would peak during 2014. Several effects contribute to the smaller prediction when compared with other geomagnetic-precursor predictions. During Solar Cycle 23 the correlation between sunspot number and F(10.7) shows that F(10.7) is higher than the equivalent sunspot number over most of the cycle, implying that the sunspot number underestimates the solar-activity component described by F(10.7). During 2003 the correlation between aa and Ap shows that aa is 10 % higher than the value predicted from Ap, leading to an overestimate of the aa precursor for that year. However, the most important difference is the lack of recurrent activity in the first three peaks and the presence of significant recurrent activity in the fourth. While the prediction is for an amplitude of Solar Cycle 24 of

  17. Production of bio-based materials using photobioreactors with binary cultures

    DOEpatents

    Beliaev, Alex S; Pinchuk, Grigoriy E; Hill, Eric A; Fredrickson, Jim K

    2013-08-27

    A method, device and system for producing preselected products, (either finished products or preselected intermediary products) from biobased precursors or CO.sub.2 and/or bicarbonate. The principal features of the present invention include a method wherein a binary culture is incubated with a biobased precursor in a closed system to transform at least a portion of the biobased precursor to a preselected product. The present invention provides a method of cultivation that does not need sparging of a closed bioreactor to remove or add a gaseous byproduct or nutrient from a liquid medium. This improvement leads to significant savings in energy consumption and allows for the design of photobioreactors of any desired shape. The present invention also allows for the use of a variety of types of waste materials to be used as the organic starting material.

  18. Production of bio-based materials using photobioreactors with binary cultures

    DOEpatents

    Beliaev, Alex S.; Pinchuk, Grigoriy E.; Hill, Eric A.

    2017-01-31

    A method, device and system for producing preselected products, (either finished products or preselected intermediary products) from biobased precursors or CO.sub.2 and/or bicarbonate. The principal features of the present invention include a method wherein a binary culture is incubated with a biobased precursor in a closed system to transform at least a portion of the biobased precursor to a preselected product. The present invention provides a method of cultivation that does not need sparging of a closed bioreactor to remove or add a gaseous byproduct or nutrient from a liquid medium. This improvement leads to significant savings in energy consumption and allows for the design of photobioreactors of any desired shape. The present invention also allows for the use of a variety of types of waste materials to be used as the organic starting material.

  19. High Tc superconducting films from metallo-organic precursors

    NASA Astrophysics Data System (ADS)

    Davison, W. W.; Shyu, S. G.; Buchanan, R. C.

    High Tc superconducting films of heavy metal soaps (derived from carboxylic acid precursors) have been prepared on Si and other substrates. The precursors were synthesized and mixed in appropriate molar ratios to form the high Tc compound YBa2Cu3O(7-x), using a high boiling point common solvent base. The precursor solution was deposited by a spin casting technique on the substrates. Film thicknesses of 0.1-1.0 micron were achieved after heat treatment at 550-850 C at not longer than 4 hours. Films were analyzed as to orientation, appropriate phase, interfacial reaction, and superconducting properties.

  20. Magnetic high throughput screening system for the development of nano-sized molecularly imprinted polymers for controlled delivery of curcumin.

    PubMed

    Piletska, Elena V; Abd, Bashar H; Krakowiak, Agata S; Parmar, Anitha; Pink, Demi L; Wall, Katie S; Wharton, Luke; Moczko, Ewa; Whitcombe, Michael J; Karim, Kal; Piletsky, Sergey A

    2015-05-07

    Curcumin is a versatile anti-inflammatory and anti-cancer agent known for its low bioavailability, which could be improved by developing materials capable of binding and releasing drug in a controlled fashion. The present study describes the preparation of magnetic nano-sized Molecularly Imprinted Polymers (nanoMIPs) for the controlled delivery of curcumin and their high throughput characterisation using microtitre plates modified with magnetic inserts. NanoMIPs were synthesised using functional monomers chosen with the aid of molecular modelling. The rate of release of curcumin from five polymers was studied under aqueous conditions and was found to correlate well with the binding energies obtained computationally. The presence of specific monomers was shown to be significant in ensuring effective binding of curcumin and to the rate of release obtained. Characterisation of the polymer particles was carried out using dynamic light scattering (DLS) technique and scanning electron microscopy (SEM) in order to establish the relationship between irradiation time and particle size. The protocols optimised during this study could be used as a blueprint for the development of nanoMIPs capable of the controlled release of potentially any compound of interest.

  1. Thin HTSC films produced by a polymer metal precursor technique

    NASA Astrophysics Data System (ADS)

    Lampe, L. v.; Zygalsky, F.; Hinrichsen, G.

    In precursors the metal ions are combined with acid groups of polymethacrylic acid (PMAA), polyacrylic acid (PAA) or novolac. Compared to thermal degradation temperature of pure polymers those of precursors are low. Precursors films were patterned by UV lithography. Diffractometric investigations showed that the c-axis oriented epitaxial films of YBa 2Cu 3O x and Bi 2Sr 2CaCu 2O x originated from amorphous metal oxide films, which were received after thermal degradation of the precursor. Transition temperatures and current densities were determined by electric resistivity measurements.

  2. The EM Earthquake Precursor

    NASA Astrophysics Data System (ADS)

    Jones, K. B., II; Saxton, P. T.

    2013-12-01

    Many attempts have been made to determine a sound forecasting method regarding earthquakes and warn the public in turn. Presently, the animal kingdom leads the precursor list alluding to a transmission related source. By applying the animal-based model to an electromagnetic (EM) wave model, various hypotheses were formed, but the most interesting one required the use of a magnetometer with a differing design and geometry. To date, numerous, high-end magnetometers have been in use in close proximity to fault zones for potential earthquake forecasting; however, something is still amiss. The problem still resides with what exactly is forecastable and the investigating direction of EM. After the 1989 Loma Prieta Earthquake, American earthquake investigators predetermined magnetometer use and a minimum earthquake magnitude necessary for EM detection. This action was set in motion, due to the extensive damage incurred and public outrage concerning earthquake forecasting; however, the magnetometers employed, grounded or buried, are completely subject to static and electric fields and have yet to correlate to an identifiable precursor. Secondly, there is neither a networked array for finding any epicentral locations, nor have there been any attempts to find even one. This methodology needs dismissal, because it is overly complicated, subject to continuous change, and provides no response time. As for the minimum magnitude threshold, which was set at M5, this is simply higher than what modern technological advances have gained. Detection can now be achieved at approximately M1, which greatly improves forecasting chances. A propagating precursor has now been detected in both the field and laboratory. Field antenna testing conducted outside the NE Texas town of Timpson in February, 2013, detected three strong EM sources along with numerous weaker signals. The antenna had mobility, and observations were noted for recurrence, duration, and frequency response. Next, two

  3. Stimulated Brillouin scattering of laser in semiconductor plasma embedded with nano-sized grains

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sharma, Giriraj, E-mail: grsharma@gmail.com; Dad, R. C.; Ghosh, S.

    2015-07-31

    A high power laser propagating through semiconductor plasma undergoes Stimulated Brillouin scattering (SBS) from the electrostrictively generated acoustic perturbations. We have considered that nano-sized grains (NSGs) ions are embedded in semiconductor plasma by means of ion implantation. The NSGs are bombarded by the surrounding plasma particles and collect electrons. By considering a negative charge on the NSGs, we present an analytically study on the effects of NSGs on threshold field for the onset of SBS and Brillouin gain of generated Brillouin scattered mode. It is found that as the charge on the NSGs builds up, the Brillouin gain is significantlymore » raised and the threshold pump field for the onset of SBS process is lowered.« less

  4. Notched-noise precursors improve detection of low-frequency amplitude modulationa)

    PubMed Central

    Almishaal, Ali; Bidelman, Gavin M.; Jennings, Skyler G.

    2017-01-01

    Amplitude modulation (AM) detection was measured with a short (50 ms), high-frequency carrier as a function of carrier level (Experiment I) and modulation frequency (Experiment II) for conditions with or without a notched-noise precursor. A longer carrier (500 ms) was also included in Experiment I. When the carrier was preceded by silence (no precursor condition) AM detection thresholds worsened for moderate-level carriers compared to lower- or higher-level carriers, resulting in a “mid-level hump.” AM detection thresholds with a precursor were better than those without a precursor, primarily for moderate-to-high level carriers, thus eliminating the mid-level hump in AM detection. When the carrier was 500 ms, AM thresholds improved by a constant (across all levels) relative to AM thresholds with a precursor, consistent with the longer carrier providing more “looks” to detect the AM signal. Experiment II revealed that improved AM detection with compared to without a precursor is limited to low-modulation frequencies (<60 Hz). These results are consistent with (1) a reduction in cochlear gain over the course of the precursor perhaps via the medial olivocochlear reflex or (2) a form of perceptual enhancement which may be mediated by adaptation of inhibition. PMID:28147582

  5. Synthesis and Characterization of the First Liquid Single Source Precursors for the Deposition of Ternary Chalcopyrite (CuInS2) Thin Film Materials

    NASA Technical Reports Server (NTRS)

    Banger, Kulbinder K.; Cowen, Jonathan; Hepp, Aloysius

    2002-01-01

    Molecular engineering of ternary single source precursors based on the [{PBu3}2Cu(SR')2In(SR')2] architecture have afforded the first liquid CIS ternary single source precursors (when R = Et, n-Pr), which are suitable for low temperature deposition (< 350 C). Thermogravimetric analyses (TGA) and modulated-differential scanning calorimetry (DSC) confirm their liquid phase and reduced stability. X-ray diffraction studies, energy dispersive analyzer (EDS), and scanning electron microscopy (SEM) support the formation of the single-phase chalcopyrite CuInS2 at low temperatures.

  6. Preparation of glass-forming materials from granulated blast furnace slag

    NASA Astrophysics Data System (ADS)

    Alonso, M.; Sáinz, E.; Lopez, F. A.

    1996-10-01

    Glass precursor materials, to be used for the vitrification of hazardous wastes, have been prepared from blast furnace slag powder through a sol-gel route. The slag is initially reacted with a mixture of alcohol (ethanol or methanol) and mineral acid (HNO3 or H2SO4) to give a sol principally consisting of Si, Ca, Al, and Mg alkoxides. Gelation is carried out with variable amounts of either ammonia or water. The gelation rate can be made as fast as desired by adding excess hydrolizing agent or else by distilling the excess alcohol out of the alkoxide solution. The resulting gel is first dried at low temperature and ground. The powder thus obtained is then heat treated at several temperatures. The intermediate and final materials are characterized by thermal analysis, infrared (IR) spectroscopy, X-ray diffraction, scanning electron microscopy (SEM), and chemical analysis. From the results, the operating conditions yielding a variety of glass precursors differing in their composition are established. The method, in comparison with direct vitrification of slag, presents a number of advantages: (1) the glass precursor obtained devitrifies at higher temperatures; (2) it enables the adjustment, to a certain extent, of the chemical composition of the glass precursor; and (3) it permits recovering marketable materials at different stages of the process.

  7. Microbial degradation of plant leachate alters lignin phenols and trihalomethane precursors

    USGS Publications Warehouse

    Pellerin, Brian A.; Hernes, Peter J.; Saraceno, John Franco; Spencer, Robert G.M.; Bergamaschi, Brian A.

    2010-01-01

    Although the importance of vascular plant-derived dissolved organic carbon (DOC) in freshwater systems has been studied, the role of leached DOC as precursors of disinfection byproducts (DBPs) during drinking water treatment is not well known. Here we measured the propensity of leachates from four crops and four aquatic macrophytes to form trihalomethanes (THMs)—a regulated class of DBPs—before and after 21 d of microbial degradation. We also measured lignin phenol content and specific UV absorbance (SUVA254) to test the assumption that aromatic compounds from vascular plants are resistant to microbial degradation and readily form DBPs. Leaching solubilized 9 to 26% of total plant carbon, which formed 1.93 to 6.72 mmol THM mol C-1 However, leachate DOC concentrations decreased by 85 to 92% over the 21-d incubation, with a concomitant decrease of 67 to 92% in total THM formation potential. Carbon-normalized THM yields in the residual DOC pool increased by 2.5 times on average, consistent with the preferential uptake of nonprecursor material. Lignin phenol concentrations decreased by 64 to 96% over 21 d, but a lack of correlation between lignin content and THM yields or SUVA254 suggested that lignin-derived compounds are not the source of increased THM precursor yields in the residual DOC pool. Our results indicate that microbial carbon utilization alters THM precursors in ecosystems with direct plant leaching, but more work is needed to identify the specific dissolved organic matter components with a greater propensity to form DBPs and affect watershed management, drinking water quality, and human health.

  8. Enabling Surgical Placement of Hydrogels through Achieving Paste-Like Rheological Behavior in Hydrogel Precursor Solutions

    PubMed Central

    Beck, Emily C.; Lohman, Brooke L.; Tabakh, Daniel B.; Kieweg, Sarah L.; Gehrke, Stevin H.; Berkland, Cory J.; Detamore, Michael S.

    2015-01-01

    Hydrogels are a promising class of materials for tissue regeneration, but they lack the ability to be molded into a defect site by a surgeon because hydrogel precursors are liquid solutions that are prone to leaking during placement. Therefore, although the main focus of hydrogel technology and developments are on hydrogels in their crosslinked form, our primary focus is on improving the fluid behavior of hydrogel precursor solutions. In this work, we introduce a method to achieve paste-like hydrogel precursor solutions by combining hyaluronic acid nanoparticles with traditional crosslinked hyaluronic acid hydrogels. Prior to crosslinking, the samples underwent rheological testing to assess yield stress and recovery using linear hyaluronic acid as a control. The experimental groups containing nanoparticles were the only solutions that exhibited a yield stress, demonstrating that the nanoparticulate rather than the linear form of hyaluronic acid was necessary to achieve paste-like behavior. The gels were also photocrosslinked and further characterized as solids, where it was demonstrated that the inclusion of nanoparticles did not adversely affect the compressive modulus and that encapsulated bone marrow-derived mesenchymal stem cells remained viable. Overall, this nanoparticle-based approach provides a platform hydrogel system that exhibits a yield stress prior to crosslinking, and can then be crosslinked into a hydrogel that is capable of encapsulating cells that remain viable. This behavior may hold significant impact for hydrogel applications where a paste-like behavior is desired in the hydrogel precursor solution. PMID:25691398

  9. Preparation of LaB{sub 3}O{sub 6}:Eu{sup 3+} phosphors by a facile precursor method and their luminescent properties

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Xia; Liang, Pan; Huang, Hong-Sheng

    2014-04-01

    Graphical abstract: LaB{sub 3}O{sub 6}:Eu{sup 3+} phosphor was obtained by calcining the precursor which was synthesized by boric acid melting method. It (a) exhibits much stronger PL intensity than that (b) prepared by conventional solid state reaction method. - Highlights: • A calcining precursor method was used for preparation of LaB{sub 3}O{sub 6}:Eu{sup 3+} phosphor. • Precursor was prepared by boric acid melting method. • The luminescence intensity of LaB{sub 3}O{sub 6}:Eu{sup 3+} was enhanced by the present method. - Abstract: The LaB{sub 3}O{sub 6}:Eu{sup 3+} phosphors were prepared by calcining the precursors which were synthesized by boric acid meltingmore » method using rare earth oxide and boric acid as raw materials, and they were characterized by EDS, XRD, IR, SEM and PL. The influences of reaction temperature for the preparation of precursor and subsequent calcination temperature and time of precursor on the luminescence properties of LaB{sub 3}O{sub 6}:Eu{sup 3+} phosphor were investigated. The results showed that the LaB{sub 3}O{sub 6}:Eu{sup 3+} phosphors with maximum luminescent intensity were obtained by calcining precursor at 1000 °C for 6 h, in which the precursor was prepared at 200 °C for 72 h. Compared with the conventional high temperature solid-state reaction method, the pure LaB{sub 3}O{sub 6}:Eu{sup 3+} phosphor can be obtained at relatively lower calcination temperature by the precursor method and exhibits much stronger emission intensity.« less

  10. Effect of precursor supply on structural and morphological characteristics of fe nanomaterials synthesized via chemical vapor condensation method.

    PubMed

    Ha, Jong-Keun; Ahn, Hyo-Jun; Kim, Ki-Won; Nam, Tae-Hyun; Cho, Kwon-Koo

    2012-01-01

    Various physical, chemical and mechanical methods, such as inert gas condensation, chemical vapor condensation, sol-gel, pulsed wire evaporation, evaporation technique, and mechanical alloying, have been used to synthesize nanoparticles. Among them, chemical vapor condensation (CVC) has the benefit of its applicability to almost all materials because a wide range of precursors are available for large-scale production with a non-agglomerated state. In this work, Fe nanoparticles and nanowires were synthesized by chemical vapor condensation method using iron pentacarbonyl (Fe(CO)5) as the precursor. The effect of processing parameters on the microstructure, size and morphology of Fe nanoparticles and nanowires were studied. In particular, we investigated close correlation of size and morphology of Fe nanoparticles and nanowires with atomic quantity of inflow precursor into the electric furnace as the quantitative analysis. The atomic quantity was calculated by Boyle's ideal gas law. The Fe nanoparticles and nanowires with various diameter and morphology have successfully been synthesized by the chemical vapor condensation method.

  11. Wet-chemical synthesis of different bismuth telluride nanoparticles using metal organic precursors - single source vs. dual source approach.

    PubMed

    Bendt, Georg; Weber, Anna; Heimann, Stefan; Assenmacher, Wilfried; Prymak, Oleg; Schulz, Stephan

    2015-08-28

    Thermolysis of the single source precursor (Et2Bi)2Te in DIPB at 80 °C yielded phase-pure Bi4Te3 nanoparticles, while mixtures of Bi4Te3 and elemental Bi were formed at higher temperatures. In contrast, cubic Bi2Te particles were obtained by thermal decomposition of Et2BiTeEt in DIPB. Moreover, a dual source approach (hot injection method) using the reaction of Te(SiEt3)2 and Bi(NMe2)3 was applied for the synthesis of different pure Bi-Te phases including Bi2Te, Bi4Te3 and Bi2Te3, which were characterized by PXRD, REM, TEM and EDX. The influence of reaction temperature, precursor molar ratio and thermolysis conditions on the resulting material phase was verified. Moreover, reactions of alternate bismuth precursors such as Bi(NEt2)3, Bi(NMeEt)3 and BiCl3 with Te(SiEt3)2 were investigated.

  12. Spectroscopic determination of thermal impulse in sub-second heating events using lanthanide-doped oxide precursors and phenomenological modeling

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Anderson, Benjamin R., E-mail: branderson@wsu.edu; Gunawidjaja, Ray; Price, Patrick

    2016-08-28

    Using a mixture of crystalline-Ho:ZrO{sub 2}, precursor-Dy:Y{sub 2}O{sub 3}, and precursor-Eu:ZrO{sub 2} nanoparticles we develop thermal impulse sensors capable of measuring equivalent isothermal temperatures and durations during a heating event, with response times of <100 ms, and a temperature range of at least 673 K to 1173 K. In order to determine the temperature and duration from the sensors after the heating event we measure the sensors' fluorescence spectrum, which is then compared with lab based calibration data. By using two precursor materials with different reaction kinetics we are able to extract both temperature and duration. Based on blind sample testing we findmore » that the sensors and calculation method are accurate for measuring temperature and duration, but currently suffer a lack of precision due to difficulties in producing homogeneously heated samples.« less

  13. Nanosized Drug Delivery Systems in Gastrointestinal Targeting: Interactions with Microbiota

    PubMed Central

    Karavolos, Michail; Holban, Alina

    2016-01-01

    The new age of nanotechnology has signaled a stream of entrepreneurial possibilities in various areas, form industry to medicine. Drug delivery has benefited the most by introducing nanostructured systems in the transport and controlled release of therapeutic molecules at targeted sites associated with a particular disease. As many nanosized particles reach the gastrointestinal tract by various means, their interactions with the molecular components of this highly active niche are intensively investigated. The well-characterized antimicrobial activities of numerous nanoparticles are currently being considered as a reliable and efficient alternative to the eminent world crisis in antimicrobial drug discovery. The interactions of nanosystems present in the gastrointestinal route with host microbiota is unavoidable; hence, a major research initiative is needed to explore the mechanisms and effects of these nanomaterials on microbiota and the impact that microbiota may have in the outcome of therapies entailing drug delivery nanosystems through the gastrointestinal route. These coordinated studies will provide novel techniques to replace or act synergistically with current technologies and help develop new treatments for major diseases via the discovery of unique antimicrobial molecules. PMID:27690060

  14. Quantum cascade laser-based screening portal for the detection of explosive precursors

    NASA Astrophysics Data System (ADS)

    Lindley, Ruth; Normand, Erwan; Howieson, Iain; McCulloch, Michael; Black, Paul; Lewis, Colin; Foulger, Brian

    2007-10-01

    In recent years, quantum cascade lasers (QCL) have been proven in robust, high-performance gas analyzers designed for continuous emission monitoring (CEM) in harsh environments. In 2006, Cascade Technologies reported progress towards adapting its patented technology for homeland security applications by publishing initial results on explosive compound detection. This paper presents the performance and results from a QCL-based people screening portal developed during the past year and aimed at the detection of precursors used in the make up of improvised explosive devices (IED). System tests have been carried out on a large number of potential interferents, together with target precursor materials, reinforcing original assumptions that compound fingerprinting can be effectively demonstrated using this technique. Results have shown that an extremely high degree of specificity can be achieved with a sub-second response time. Furthermore, it has been shown that unambiguous precursor signature recognition can be extended to compound mixtures associated with the intermediate stages in the make up of IEDs, whilst maintaining interferent immunity. The portal sensitivity was configured for parts per billion (ppb) detection level thresholds, but is currently being reconfigured for sub-ppb detection. In summary, the results obtained from the QCL based portal indicate that development of a low cost detection system, with enhanced features such as low false positive and high throughput screening of individuals or items, is possible. Development and testing was carried out with the support of the UK government.

  15. Natural attenuation of NDMA precursors in an urban, wastewater-dominated wash.

    PubMed

    Woods, Gwen C; Dickenson, Eric R V

    2016-02-01

    N-Nitrosodimethylamine (NDMA) is a disinfection by-product (DBP) that is potentially carcinogenic and has been found to occur in drinking water treatment systems impacted with treated wastewater. A major gap in NDMA research is an understanding of the persistence of wastewater-derived precursors within the natural environment. This research sought to fill this knowledge gap by surveying NDMA precursors across the length of a wastewater effluent-dominated wash. Significant precursor reduction (17%) was found to occur from introduction into the wash to a point 9 h downstream. This reduction translates into a half-life of roughly 32 h for bulk NDMA precursors. Further laboratory experiments examining rates of photolysis, biodegradation and loss to sediments, illustrated that both photolytic and biological degradation were effective removal mechanisms for NDMA precursors. Loss to sediments that were acquired from the wash did not appear to reduce NDMA precursors in the water column, although a control conducted with DI water provided evidence that significant NDMA precursors could be released from autoclaved sediments (suggesting that sorption does occur). Microbial experiments revealed that microbes associated with sediments were much more effective at degrading precursors than microbes within the water column. Overall, this study demonstrated that natural processes are capable of attenuating NDMA precursors relatively quickly within the environment, and that utilities might benefit from maximizing source water residency time in the environment, prior to introduction into treatment plants. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Analysis of Precursor Properties of mixed Al/Alumel Cylindrical Wire Arrays*

    NASA Astrophysics Data System (ADS)

    Stafford, A.; Safronova, A. S.; Kantsyrev, V. L.; Esaulov, A. A.; Weller, M. E.; Shrestha, I.; Osborne, G. C.; Shlyaptseva, V. V.; Keim, S. F.; Coverdale, C. A.; Chuvatin, A. S.

    2012-10-01

    Previous studies of mid-Z (Cu and Ni) cylindrical wire arrays (CWAs) on Zebra have found precursors with high electron temperatures of >300 eV. However, past experiments with Al CWAs did not find the same high temperature precursors. New precursor experiments using mixed Al/Alumel (Ni 95%, Si 2%, and Al 2%) cylindrical wire arrays have been performed to understand how the properties of L-shell Ni precursor will change and whether Al precursor will be observed. Time gated spectra and pinholes are used to determine precursor plasma conditions for comparison with previous Alumel precursor experiments. A full diagnostic set which included more than ten different beam-lines was implemented. Future work in this direction is discussed. [4pt] *This work was supported by NNSA under DOE Cooperative Agreements DE-FC52-06NA27588, and in part by DE-FC52-06NA27586, and DE-FC52-06NA27616. Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94AL85000.

  17. Surface functionalized mesoporous material and method of making same

    DOEpatents

    Feng, Xiangdong [West Richland, WA; Liu, Jun [West Richland, WA; Fryxell, Glen E [Kennewick, WA

    2001-12-04

    According to the present invention, an organized assembly of functional molecules with specific interfacial functionality (functional group(s)) is attached to available surfaces including within mesopores of a mesoporous material. The method of the present invention avoids the standard base soak that would digest the walls between the mesopores by boiling the mesoporous material in water for surface preparation then removing all but one or two layers of water molecules on the internal surface of a pore. Suitable functional molecule precursor is then applied to permeate the hydrated pores and the precursor then undergoes condensation to form the functional molecules on the interior surface(s) of the pore(s).

  18. Subcellular Distribution of Glutathione Precursors in Arabidopsis thaliana

    PubMed Central

    Koffler, Barbara Eva; Maier, Romana; Zechmann, Bernd

    2011-01-01

    Abstract Glutathione is an important antioxidant and has many important functions in plant development, growth and defense. Glutathione synthesis and degradation is highly compartment-specific and relies on the subcellular availability of its precursors, cysteine, glutamate, glycine and γ-glutamylcysteine especially in plastids and the cytosol which are considered as the main centers for glutathione synthesis. The availability of glutathione precursors within these cell compartments is therefore of great importance for successful plant development and defense. The aim of this study was to investigate the compartment-specific importance of glutathione precursors in Arabidopsis thaliana. The subcellular distribution was compared between wild type plants (Col-0), plants with impaired glutathione synthesis (glutathione deficient pad2-1 mutant, wild type plants treated with buthionine sulfoximine), and one complemented line (OE3) with restored glutathione synthesis. Immunocytohistochemistry revealed that the inhibition of glutathione synthesis induced the accumulation of the glutathione precursors cysteine, glutamate and glycine in most cell compartments including plastids and the cytosol. A strong decrease could be observed in γ-glutamylcysteine (γ-EC) contents in these cell compartments. These experiments demonstrated that the inhibition of γ-glutamylcysteine synthetase (GSH1) – the first enzyme of glutathione synthesis – causes a reduction of γ-EC levels and an accumulation of all other glutathione precursors within the cells. PMID:22050910

  19. Isolation of pheromone precursor genes of Magnaporthe grisea.

    PubMed

    Shen, W C; Bobrowicz, P; Ebbole, D J

    1999-01-01

    In heterothallic ascomycetes one mating partner serves as the source of female tissue and is fertilized with spermatia from a partner of the opposite mating type. The role of pheromone signaling in mating is thought to involve recognition of cells of the opposite mating type. We have isolated two putative pheromone precursor genes of Magnaporthe grisea. The genes are present in both mating types of the fungus but they are expressed in a mating type-specific manner. The MF1-1 gene, expressed in Mat1-1 strains, is predicted to encode a 26-amino-acid polypeptide that is processed to produce a lipopeptide pheromone. The MF2-1 gene, expressed in Mat1-2 strains, is predicted to encode a precursor polypeptide that is processed by a Kex2-like protease to yield a pheromone with striking similarity to the predicted pheromone sequence of a close relative, Cryphonectria parasitica. Expression of the M. grisea putative pheromone precursor genes was observed under defined nutritional conditions and in field isolates. This suggests that the requirement for complex media for mating and the poor fertility of field isolates may not be due to limitation of pheromone precursor gene expression. Detection of putative pheromone precursor gene mRNA in conidia suggests that pheromones may be important for the fertility of conidia acting as spermatia. Copyright 1999 Academic Press.

  20. [Endometrial carcinomas and precursor lesions--new aspects].

    PubMed

    Schmidt, D

    2009-07-01

    Endometrial carcinomas can be separated into two groups which are designated as type I and type II carcinomas today. Both groups of tumors are clearly different with regard to conventional light microscopy, immunohistochemistry, molecular pathology and clinical features. Only type I carcinomas are associated with hyperestrogenism. The group of type I carcinomas consists of endometrioid carcinoma and its variants, and mucinous carcinoma. The prototypes of type II carcinomas are serous and clear cell carcinoma. Not all carcinomas, however, can be assigned to one of the two groups, because there are hybrid tumors and mixed carcinomas, e.g. endometrioid carcinoma with a serous component. The precursor lesions of the endometrioid carcinoma and the serous carcinoma are well characterized morphologically and by molecular pathology. Atypical hyperplasia is the precursor lesion of endometrioid carcinoma, whereas endometrial intraepithelial carcinoma (EIC) is the precursor lesion of serous carcinoma. No precursor lesion has as yet been identified for clear cell carcinoma. Immunohistochemical markers for endometrial carcinoma are CK7 and vimentin, for serous carcinoma markers are p53 and p16. Correct typing is of essential prognostic necessity in endometrial carcinoma. Of utmost importance is the detection of a serous component, because serous carcinoma leads to early tumor spread with the necessity of radical surgery, chemotherapy and radiotherapy.

  1. Towards deriving Ni-rich cathode and oxide-based anode materials from hydroxides by sharing a facile co-precipitation method.

    PubMed

    Qiu, Haifa; Du, Tengfei; Wu, Junfeng; Wang, Yonglong; Liu, Jian; Ye, Shihai; Liu, Sheng

    2018-05-22

    Although intensive studies have been conducted on layered transition metal oxide(TMO)-based cathode materials and metal oxide-based anode materials for Li-ion batteries, their precursors generally follow different or even complex synthesis routes. To share one route for preparing precursors of the cathode and anode materials, herein, we demonstrate a facile co-precipitation method to fabricate Ni-rich hydroxide precursors of Ni0.8Co0.1Mn0.1(OH)2. Ni-rich layered oxide of LiNi0.8Co0.1Mn0.1O2 is obtained by lithiation of the precursor in air. An NiO-based anode material is prepared by calcining the precursor or multi-walled carbon nanotubes (MWCNTs) incorporated precursors. The pre-addition of ammonia solution can simplify the co-precipitation procedures and the use of an air atmosphere can also make the heat treatment facile. LiNi0.8Co0.1Mn0.1O2 as the cathode material delivers a reversible capacity of 194 mA h g-1 at 40 mA g-1 and a notable cycling retention of 88.8% after 100 cycles at 200 mA g-1. This noticeable performance of the cathode arises from a decent particle morphology and high crystallinity of the layered oxides. As the anode material, the MWCNTs-incorporated oxides deliver a much higher reversible capacity of 811.1 mA h g-1 after 200 cycles compared to the pristine oxides without MWCNTs. The improvement on electrochemical performance can be attributed to synergistic effects from MWCNTs incorporation, including reinforced electronic conductivity, rich meso-pores and an alleviated volume effect. This facile and sharing method may offer an integrated and economical approach for commercial production of Ni-rich electrode materials for Li-ion batteries.

  2. Method for dispersing catalyst onto particulate material and product thereof

    DOEpatents

    Utz, Bruce R.; Cugini, Anthony V.

    1992-01-01

    A method for dispersing finely divided catalyst precursors onto the surface of coal or other particulate material includes the steps of forming a wet paste mixture of the particulate material and a liquid solution containing a dissolved transition metal salt, for instance a solution of ferric nitrate. The wet paste mixture is in a state of incipient wetness with all of this solution adsorbed onto the surfaces of the particulate material without the presence of free moisture. On adding a precipitating agent such as ammonia, a catalyst precursor such as hydrated iron oxide is deposited on the surfaces of the coal. The catalyst is activated by converting it to the sulfide form for the hydrogenation or direct liquefaction of the coal.

  3. Spectral-optical-electrical-thermal properties of deposited thin films of nano-sized calcium(II)-8-hydroxy-5,7-dinitroquinolate complex.

    PubMed

    Farag, A A M; Haggag, Sawsan M S; Mahmoud, Mohamed E

    2011-11-01

    Spectral-optical-electrical-thermal properties of deposited thin films of nano-sized calcium(II)-8-hydroxy-5,7-dinitroquinolate complex, Ca[((NO(2))(2)-8HQ)(2)], were explored, studied and evaluated in this work. Thin films of Ca[((NO(2))(2)-8HQ)(2)] were assembled by using a direct, simple and efficient layer-by-layer (LBL) chemical deposition technique. The optical properties of thin films were investigated by using spectrophotometric measurements of transmittance and reflectance at normal incidence in the wavelength range 200-2500 nm. The refractive index, n, and the absorption index, k, of Ca[((NO(2))(2)-8HQ)(2)] films were determined from the measured transmittance and reflectance. The real and imaginary dielectric constants were also determined. The analysis of the spectral behavior of the absorption coefficient in the intrinsic absorption region reveals a direct allowed transition with band gaps of 1.1 eV and 2.4 eV for the optical and transport energy gaps, respectively. The current-voltage characteristics of Ca[((NO(2))(2)-8HQ)(2)] showed a trap-charge limited conduction in determining the current at the intermediate and high bias regimes. Graphical representation of the current-voltage characteristics yields three distinct linear parts indicating the existence of three conduction mechanisms. Structural characterization and identification were confirmed by using Fourier transform infrared spectroscopy (FT-IR). Scanning electron microscopy (SEM) was also used to image the surface morphology of the deposited nano-sized metal complex and such study revealed a high homogeneity in surface spherical particle distribution with average particles size in the range 20-40 nm. Thermal gravimetric analysis (TGA) was also studied for [(NO(2))(2)-8HQ] and Ca[((NO(2))(2)-8HQ)(2)] to evaluate and confirm the thermal stability characteristics incorporated into the synthesized nano-sized Ca[((NO(2))(2)-8HQ)(2)] complex. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. Mexico's methamphetamine precursor chemical interventions: impacts on drug treatment admissions.

    PubMed

    Cunningham, James K; Bojorquez, Ietza; Campollo, Octavio; Liu, Lon-Mu; Maxwell, Jane Carlisle

    2010-11-01

    To help counter problems related to methamphetamine, Mexico has implemented interventions targeting pseudoephedrine and ephedrine, the precursor chemicals commonly used in the drug's synthesis. This study examines whether the interventions impacted methamphetamine treatment admissions-an indicator of methamphetamine consequences. Quasi-experiment: autoregressive integrated moving average (ARIMA)-based intervention time-series analysis. precursor chemical restrictions implemented beginning November 2005; major rogue precursor chemical company closed (including possibly the largest single drug-cash seizure in history) March 2007; precursor chemicals banned from Mexico (North America's first precursor ban) August 2008. Mexico and Texas (1996-2008). Monthly treatment admissions for methamphetamine (intervention series) and cocaine, heroin and alcohol (quasi-control series). The precursor restriction was associated with temporary methamphetamine admissions decreases of 12% in Mexico and 11% in Texas. The company closure was associated with decreases of 56% in Mexico and 48% in Texas; these decreases generally remained to the end of the study period. Neither intervention was associated with significant changes in the Mexico or Texas quasi-control series. The analysis of Mexico's ban was indeterminate due largely to a short post-ban series. This study, one of the first quasi-experimental analyses of an illicit-drug policy in Mexico, indicates that the country's precursor interventions were associated with positive impacts domestically and in one of the Unites States' most populous states--Texas. These interventions, coupled with previous US and Canadian interventions, amount to a new, relatively cohesive level of methamphetamine precursor control across North America's largest nations, raising the possibility that the impacts found here could continue for an extended period. © 2010 The Authors. Journal compilation © 2010 Society for the Study of Addiction.

  5. Removal of precursors and disinfection by-products (DBPs) by membrane filtration from water; a review.

    PubMed

    Zazouli, Mohammad Ali; Kalankesh, Laleh R

    2017-01-01

    Disinfection by-products (DBPs) have heterogeneous structures which are suspected carcinogens as a result of reactions between NOMs (Natural Organic Matter) and oxidants/disinfectants such as chlorine. Because of variability in DBPs characteristics, eliminate completely from drinking water by single technique is impossible. The current article reviews removal of the precursors and DBPs by different membrane filtration methods such as Microfiltration (MF), Ultrafiltration (UF), Nanofiltration (NF) and Reverse Osmosis (RO) techniques. Also, we provide an overview of existing and potentially Membrane filtration techniques, highlight their strengths and drawbacks. MF membranes are a suitable alternative to remove suspended solids and colloidal materials. However, NOMs fractions are effectively removed by negatively charged UF membrane. RO can remove both organic and inorganic DBPs and precursors simultaneously. NF can be used to remove compounds from macromolecular size to multivalent ions.

  6. Damage Precursor Investigation of Fiber-Reinforced Composite Materials Under Fatigue Loads

    DTIC Science & Technology

    2013-09-01

    19.21, 215713. Thostenson, E. T.; Chou, T.‐W. Carbon Nanotube Networks: Sensing of Distributed Strain and Damage for Life Prediction and Self Healing ...composite structural life and the goal of the proposed research program to develop self -responsive engineered composites. Over 80%‒90% of the life of a...composite material. It is also envisaged to investigate and develop self -responsive engineered composite materials that provide an accurate health

  7. Copper stabilization via spinel formation during the sintering of simulated copper-laden sludge with aluminum-rich ceramic precursors.

    PubMed

    Tang, Yuanyuan; Chui, Stephen Sin-Yin; Shih, Kaimin; Zhang, Lingru

    2011-04-15

    The feasibility of incorporating copper-laden sludge into low-cost ceramic products, such as construction ceramics, was investigated by sintering simulated copper-laden sludge with four aluminum-rich ceramic precursors. The results indicated that all of these precursors (γ-Al(2)O(3), corundum, kaolinite, mullite) could crystallochemically stabilize the hazardous copper in the more durable copper aluminate spinel (CuAl(2)O(4)) structure. To simulate the process of copper transformation into a spinel structure, CuO was mixed with the four aluminum-rich precursors, and fired at 650-1150 °C for 3 h. The products were examined using powder X-ray diffraction (XRD) and scanning electron microscopic techniques. The efficiency of copper transformation among crystalline phases was quantitatively determined through Rietveld refinement analysis of the XRD data. The sintering experiment revealed that the optimal sintering temperature for CuAl(2)O(4) formation was around 1000 °C and that the efficiency of copper incorporation into the crystalline CuAl(2)O(4) structure after 3 h of sintering ranged from 40 to 95%, depending on the type of aluminum precursor used. Prolonged leaching tests were carried out by using acetic acid with an initial pH value of 2.9 to leach CuO and CuAl(2)O(4) samples for 22 d. The sample leachability analysis revealed that the CuAl(2)O(4) spinel structure was more superior to stabilize copper, and suggested a promising and reliable technique for incorporating copper-laden sludge or its incineration ash into usable ceramic products. Such results also demonstrated the potential of a waste-to-resource strategy by using waste materials as part of the raw materials with the attainable temperature range used in the production of ceramics.

  8. Functional Analysis of Precursors for Serious Problem Behavior and Related Intervention

    ERIC Educational Resources Information Center

    Langdon, Nancy A.; Carr, Edward G.; Owen-DeSchryver, Jamie S.

    2008-01-01

    Precursor behaviors are innocuous behaviors that reliably precede the occurrence of problem behavior. Intervention efforts applied to precursors might prevent the occurrence of severe problem behavior. We examined the relationship between precursor behavior and problem behavior in three individuals with developmental disabilities. First, a…

  9. THE CRYSTALLIZATION AND SEROLOGICAL DIFFERENTIATION OF A STREPTOCOCCAL PROTEINASE AND ITS PRECURSOR

    PubMed Central

    Elliott, S. D.

    1950-01-01

    Grown in dialysate broth at a pH between 5.5 and 6.5, some strains of group A streptococci elaborate the precursor of a proteolytic enzyme. Within this range of hydrogen concentration the precursor is also produced when the streptococci are suspended in a peptone dialysate containing glucose and incubated at 37°C. The precursor does not appear to be produced at a neutral or alkaline reaction. Methods are described whereby the precursor and proteinase have been isolated in crystalline form. The precursor crystallizes from half-saturated ammonium sulfate at pH 8.0 and a temperature of 22°C. or higher; the proteinase crystallizes from 0.15 saturated ammonium sulfate at pH 8.0 but does so most readily at refrigerator temperature. The degree of purification achieved by these procedures is discussed. The activity of purified preparations of the precursor and of proteinase has been tested against α-benzoyl-l-arginineamide and, with this as a substrate, the conversion of precursor to proteinase by autocatalysis or by trypsin has been confirmed. Immunological experiments are described, the results of which provide evidence of the distinct antigenic specificity of the precursor and proteinase; the conversion of precursor to proteinase has been followed by means of serological tests. PMID:15436931

  10. Carbon material for hydrogen storage

    DOEpatents

    Bourlinos, Athanasios; Steriotis, Theodore; Stubos, Athanasios; Miller, Michael A

    2016-09-13

    The present invention relates to carbon based materials that are employed for hydrogen storage applications. The material may be described as the pyrolysis product of a molecular precursor such as a cyclic quinone compound. The pyrolysis product may then be combined with selected transition metal atoms which may be in nanoparticulate form, where the metals may be dispersed on the material surface. Such product may then provide for the reversible storage of hydrogen. The metallic nanoparticles may also be combined with a second metal as an alloy to further improve hydrogen storage performance.

  11. Making Single-Source Precursors of Ternary Semiconductors

    NASA Technical Reports Server (NTRS)

    Hepp, Aloysius; Banger, Kulbindre K.

    2007-01-01

    A synthesis route has been developed for the commercial manufacture of single- source precursors of chalcopyrite semiconductor absorber layers of thin-film solar photovoltaic cells. A closely related class of single-source precursors of these semiconductors, and their synthesis routes, were reported in "Improved Single-Source Precursors for Solar-Cell Absorbers" (LEW-17445-1), NASA Tech Briefs, Vol. 31, No. 6 (June 2007), page 56. The present synthesis route is better suited to commercialization because it is simpler and involves the use of commercially available agents, yet offers the flexibility needed for synthesis of a variety of precursors. A single-source precursor of the type of interest here is denoted by the general formula L2M'(mu-ER)2M(ER)2, where L signifies a Lewis base; M signifies Al, In, or Ga; M' signifies Ag or Cu; R signifies an alkyl, aryl, silyl, or perfluorocarbon group; E signifies O, S, Se, or Te; and mu signifies a bridging ligand. This compound can be synthesized in a "one-pot" procedure from ingredients that are readily available from almost any chemical supplier. In a demonstration, the following synthesis was performed: Under anaerobic conditions, InCl3 was reacted with sodium ethanethiolate in methanol in a 1:4 molar ratio to afford the ionic stable intermediate compound Na+[In(SEt)4]- (where Et signifies ethyl group). After approximately 15 minutes, a heterogeneous solution of CuCl and the Lewis base PPh3 (where Ph signifies phenyl) in a 1:2 ratio in a mixture of CH3CN and CH2Cl2 was added directly to the freshly prepared Na+[In(SEt)4]-. After 24 hours, the reaction was essentially complete. The methanolic solution was concentrated, then the product was extracted with CH2Cl2, then the product was washed with dry ether and pentane. The product in its final form was a creamy white solid. Spectroscopic and elemental analysis confirmed that the product was (PPh3)2Cu(mu-SEt)2In(mu-SEt)2, which is known to be a precursor of the ternary

  12. Plasma characterization studies for materials processing

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pfender, E.; Heberlein, J.

    New applications for plasma processing of materials require a more detailed understanding of the fundamental processes occurring in the processing reactors. We have developed reactors offering specific advantages for materials processing, and we are using modeling and diagnostic techniques for the characterization of these reactors. The emphasis is in part set by the interest shown by industry pursuing specific plasma processing applications. In this paper we report on the modeling of radio frequency plasma reactors for use in materials synthesis, and on the characterization of the high rate diamond deposition process using liquid precursors. In the radio frequency plasma torchmore » model, the influence of specific design changes such as the location of the excitation coil on the enthalpy flow distribution is investigated for oxygen and air as plasma gases. The diamond deposition with liquid precursors has identified the efficient mass transport in form of liquid droplets into the boundary layer as responsible for high growth, and the chemical properties of the liquid for the film morphology.« less

  13. Mesoporous silica obtained with methyltriethoxysilane as co-precursor in alkaline medium

    NASA Astrophysics Data System (ADS)

    Putz, Ana-Maria; Wang, Kunzhou; Len, Adél; Plocek, Jiri; Bezdicka, Petr; Kopitsa, Gennady P.; Khamova, Tamara V.; Ianăşi, Cătălin; Săcărescu, Liviu; Mitróová, Zuzana; Savii, Cecilia; Yan, Minhao; Almásy, László

    2017-12-01

    Mesoporous silica particles have been synthesized by sol-gel method from tetraethoxysilane (tetraethylorthosilicate, TEOS) and methyltriethoxysilane (MTES), in ethanol and water mixture, at different ratios of the of the silica precursors. Ammonia was used as catalyst at room temperature and hexadecyltrimethylammonium bromide (cetyltrimethylammonium bromide, CTAB) as the structure directing agent. Nitrogen sorption, X-ray diffraction and small-angle neutron scattering gave information on the evolution of the gel structure and pore morphologies in the function of MTES/TEOS molar ratio. Thermogravimetric and differential thermal analysis showed that with addition of MTES the exothermic peak indicating the oxidation of the low molecular weight organic fragments shift to higher temperature. A room-temperature, one-pot synthesis of MCM-41 type materials is presented, in which the variation of the MTES concentration allows to change the hydrophobicity, preserving the specific properties materials, like the ordered pore structure, large specific surface area and high porosity. Specifically, the obtained materials had cylindrical pores, specific surface areas up to 1101 m2/g and total pore volumes up to 0.473 cm3/g. The obtained mesoporous materials are susceptible for further functionalization to improve their selective uptake of guest species in drug delivery applications.

  14. Obtaining aluminas from the thermal decomposition of their different precursors: An {sup 27}Al MAS NMR and X-ray powder diffraction studies

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chagas, L.H.; De Carvalho, G.S.G.; San Gil, R.A.S.

    2014-01-01

    Graphical abstract: - Highlights: • We synthesized three precursors of alumina from different methods. • The calcination of the precursors generated several alumina polymorphs. • XRD and NMR were used for structural investigation of the polymorphs. • The synthesis route determines the structural and textural properties of the solids. - Abstract: A commercial sample of Boehmite was used as precursor of alumina polymorphs. For comparison, three other precursors were synthesized from different methods. Particularly, the use of excess of urea promoted a very crystalline form of basic aluminum carbonate. The characteristics of the four precursors were investigated by thermal, vibrationalmore » and X-ray powder diffraction (XRD) analysis. Additionally, the nuclear magnetic resonance, with magic angle spinning ({sup 27}Al MAS NMR), was used to verify the coordination of aluminum cations. Each precursor was calcined at various temperatures generating alumina polymorphs, which were structurally analyzed by XRD and {sup 27}Al MAS NMR. Due to interest in catalysis supports, special attention was given to the γ-Al{sub 2}O{sub 3} phase, which in addition to structural investigation was subjected to textural analysis. The results showed that, from different synthesis procedures and common route of calcination, one can obtain materials with the same composition but with different structural and textural properties, which in turn can significantly influence the performance of a supported catalyst.« less

  15. The Chemistry of Inorganic Precursors during the Chemical Deposition of Films on Solid Surfaces.

    PubMed

    Barry, Seán T; Teplyakov, Andrew V; Zaera, Francisco

    2018-03-20

    The deposition of thin solid films is central to many industrial applications, and chemical vapor deposition (CVD) methods are particularly useful for this task. For one, the isotropic nature of the adsorption of chemical species affords even coverages on surfaces with rough topographies, an increasingly common requirement in microelectronics. Furthermore, by splitting the overall film-depositing reactions into two or more complementary and self-limiting steps, as it is done in atomic layer depositions (ALD), film thicknesses can be controlled down to the sub-monolayer level. Thanks to the availability of a vast array of inorganic and metalorganic precursors, CVD and ALD are quite versatile and can be engineered to deposit virtually any type of solid material. On the negative side, the surface chemistry that takes place in these processes is often complex, and can include undesirable side reactions leading to the incorporation of impurities in the growing films. Appropriate precursors and deposition conditions need to be chosen to minimize these problems, and that requires a proper understanding of the underlying surface chemistry. The precursors for CVD and ALD are often designed and chosen based on their known thermal chemistry from inorganic chemistry studies, taking advantage of the vast knowledge developed in that field over the years. Although a good first approximation, however, this approach can lead to wrong choices, because the reactions of these precursors at gas-solid interfaces can be quite different from what is seen in solution. For one, solvents often aid in the displacement of ligands in metalorganic compounds, providing the right dielectric environment, temporarily coordinating to the metal, or facilitating multiple ligand-complex interactions to increase reaction probabilities; these options are not available in the gas-solid reactions associated with CVD and ALD. Moreover, solid surfaces act as unique "ligands", if these reactions are to be

  16. Integrated Data Collection Analysis (IDCA) Program - Mixing Procedures and Materials Compatibility

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Olinger, Becky D.; Sandstrom, Mary M.; Warner, Kirstin F.

    Three mixing procedures have been standardized for the IDCA proficiency test—solid-solid, solid-liquid, and liquid-liquid. Due to the variety of precursors used in formulating the materials for the test, these three mixing methods have been designed to address all combinations of materials. Hand mixing is recommended for quantities less than 10 grams and Jar Mill mixing is recommended for quantities over 10 grams. Consideration must also be given to the type of container used for the mixing due to the wide range of chemical reactivity of the precursors and mixtures. Eight web site sources from container and chemical manufacturers have beenmore » consulted. Compatible materials have been compiled as a resource for selecting containers made of materials stable to the mixtures. In addition, container materials used in practice by the participating laboratories are discussed. Consulting chemical compatibility tables is highly recommended for each operation by each individual engaged in testing the materials in this proficiency test.« less

  17. Structure and organization of nanosized-inclusion-containing bilayer membranes

    NASA Astrophysics Data System (ADS)

    Ren, Chun-Lai; Ma, Yu-Qiang

    2009-07-01

    Based on a considerable amount of experimental evidence for lateral organization of lipid membranes which share astonishingly similar features in the presence of different inclusions, we use a hybrid self-consistent field theory (SCFT)/density-functional theory (DFT) approach to deal with bilayer membranes embedded by nanosized inclusions and explain experimental findings. Here, the hydrophobic inclusions are simple models of hydrophobic drugs or other nanoparticles for biomedical applications. It is found that lipid/inclusion-rich domains are formed at moderate inclusion concentrations and disappear with the increase in the concentration of inclusions. At high inclusion content, chaining of inclusions occurs due to the effective depletion attraction between inclusions mediated by lipids. Meanwhile, the increase in the concentration of inclusions can also cause thickening of the membrane and the distribution of inclusions undergoes a layering transition from one-layer structure located in the bilayer midplane to two-layer structure arranged into the two leaflets of a bilayer. Our theoretical predictions address the complex interactions between membranes and inclusions suggesting a unifying mechanism which reflects the competition between the conformational entropy of lipids favoring the formation of lipid- and inclusion-rich domains in lipids and the steric repulsion of inclusions leading to the uniform dispersion.

  18. Methods of making copper selenium precursor compositions with a targeted copper selenide content and precursor compositions and thin films resulting therefrom

    DOEpatents

    Curtis, Calvin J [Lakewood, CO; Miedaner, Alexander [Boulder, CO; van Hest, Marinus Franciscus Antonius Maria; Ginley, David S [Evergreen, CO; Leisch, Jennifer [Denver, CO; Taylor, Matthew [West Simsbury, CT; Stanbery, Billy J [Austin, TX

    2011-09-20

    Precursor compositions containing copper and selenium suitable for deposition on a substrate to form thin films suitable for semi-conductor applications. Methods of forming the precursor compositions using primary amine solvents and methods of forming the thin films wherein the selection of temperature and duration of heating controls the formation of a targeted species of copper selenide.

  19. The Innate Lymphoid Cell Precursor.

    PubMed

    Ishizuka, Isabel E; Constantinides, Michael G; Gudjonson, Herman; Bendelac, Albert

    2016-05-20

    The discovery of tissue-resident innate lymphoid cell populations effecting different forms of type 1, 2, and 3 immunity; tissue repair; and immune regulation has transformed our understanding of mucosal immunity and allergy. The emerging complexity of these populations along with compounding issues of redundancy and plasticity raise intriguing questions about their precise lineage relationship. Here we review advances in mapping the emergence of these lineages from early lymphoid precursors. We discuss the identification of a common innate lymphoid cell precursor characterized by transient expression of the transcription factor PLZF, and the lineage relationships of innate lymphoid cells with conventional natural killer cells and lymphoid tissue inducer cells. We also review the rapidly growing understanding of the network of transcription factors that direct the development of these lineages.

  20. Alternative group V precursors for CVD applications

    NASA Astrophysics Data System (ADS)

    Lum, R. M.; Klingert, J. K.

    1991-01-01

    The chemical vapor deposition (CVD) techniques used to grow III/V semiconductors films, such as metalorganic vapor phase epitaxy (MOVPE), hydride VPE, chemical beam epitaxy (CBE) and gas source molecular beam epitaxy (GS-MBE), all use hydrides (AsH 3 and PH 3) as the Group V source. However, the hydrides are extremely toxic gases which are stored under high pressure (200-2000 psi). To reduce the safety hazards associated with these gases, alternative Group V precursors have been investigated. Organoarsenic and phosphorous compounds have received the most attention as replacements for AsH 3 and PH 3 because they are typically low vapor pressure liquids, and thus present significantly lower exposure risks than the hydrides. For AsH 3 these have included the methyl, ethyl and butyl-based derivatives RnAsH 3- n, with varying degrees ( n = 1-3) of hydrogen atom substitution. In this paper the growth properties, thermochemistry and toxicity of the various alkylarsine precursors are compared with arsine. Data are presented on the impact of the thermochemistry of these compounds on film electrical properties, and on the effects of precursor composition and purity on overall film quality. The suitability of alternative As-precursors for device applications is demonstrated, and selection criteria are presented for the most effective alkylarsine compound for a particular CVD growth process.

  1. Thermal annealing behavior of nano-size metal-oxide particles synthesized by ion implantation in Fe-Cr alloy

    NASA Astrophysics Data System (ADS)

    Zheng, C.; Gentils, A.; Ribis, J.; Borodin, V. A.; Descoins, M.; Mangelinck, D.; Dalle, F.; Arnal, B.; Delauche, L.

    2017-05-01

    Oxide dispersion strengthened (ODS) steels are promising structural materials for the next generation nuclear reactors, as well as fusion facilities. The detailed understanding of the mechanisms involved in the precipitation of nano-oxides during ODS steel production would strongly contribute to the improvement of the mechanical properties and the optimization of manufacturing of ODS steels, with a potentially strong economic impact for their industrialization. A useful tool for the experimental study of nano-oxide precipitation is ion implantation, a technique that is widely used to synthesize precipitate nanostructures in well-controlled conditions. Earlier, we have demonstrated the feasibility of synthesizing aluminum-oxide particles in the high purity Fe-10Cr alloy by consecutive implantation with Al and O ions at room temperature. This paper describes the effects of high-temperature annealing after the ion implantation stage on the development of the aluminum based oxide nanoparticle system. Using transmission electron microscopy and atom probe tomography experiments, we demonstrate that post-implantation heat treatment induces the growth of the nano-sized oxides in the implanted region and nucleation of new oxide precipitates behind the implantation zone as a result of the diffusion driven broadening of implant profiles. A tentative scenario for the development of metal-oxide nano-particles at both ion implantation and heat treatment stages is suggested based on the experimental observations.

  2. Potential Applications of Nanocellulose-Containing Materials in the Biomedical Field

    PubMed Central

    Halib, Nadia; Perrone, Francesca; Dapas, Barbara; Farra, Rossella; Abrami, Michela; Chiarappa, Gianluca; Forte, Giancarlo; Zanconati, Fabrizio; Pozzato, Gabriele; Murena, Luigi; Fiotti, Nicola; Lapasin, Romano; Cansolino, Laura; Grassi, Gabriele

    2017-01-01

    Because of its high biocompatibility, bio-degradability, low-cost and easy availability, cellulose finds application in disparate areas of research. Here we focus our attention on the most recent and attractive potential applications of cellulose in the biomedical field. We first describe the chemical/structural composition of cellulose fibers, the cellulose sources/features and cellulose chemical modifications employed to improve its properties. We then move to the description of cellulose potential applications in biomedicine. In this field, cellulose is most considered in recent research in the form of nano-sized particle, i.e., nanofiber cellulose (NFC) or cellulose nanocrystal (CNC). NFC is obtained from cellulose via chemical and mechanical methods. CNC can be obtained from macroscopic or microscopic forms of cellulose following strong acid hydrolysis. NFC and CNC are used for several reasons including the mechanical properties, the extended surface area and the low toxicity. Here we present some potential applications of nano-sized cellulose in the fields of wound healing, bone-cartilage regeneration, dental application and different human diseases including cancer. To witness the close proximity of nano-sized cellulose to the practical biomedical use, examples of recent clinical trials are also reported. Altogether, the described examples strongly support the enormous application potential of nano-sized cellulose in the biomedical field. PMID:28825682

  3. Strengthening Effect of Extruded Mg-8Sn-2Zn-2Al Alloy: Influence of Micro and Nano-Size Mg₂Sn Precipitates.

    PubMed

    Cheng, Weili; Bai, Yang; Wang, Lifei; Wang, Hongxia; Bian, Liping; Yu, Hui

    2017-07-18

    In this study, Mg-8Sn-2Zn-2Al (TZA822) alloys with varying Mg₂Sn contents prior to extrusion were obtained by different pre-treatments (without and with T4), and the strengthening response related to micro and nano-size Mg₂Sn precipitates in the extruded TZA822 alloys was reported. The results showed that the morphology of nano-size Mg₂Sn precipitates exhibits a significant change in basal plane from rod-like to spherical, owing to the decrement in the fraction of micro-size particles before extrusion. Meanwhile, the spherical Mg₂Sn precipitates provided a much stronger strengthening effect than did the rod-like ones, which was ascribed to uniform dispersion and refinement of spherical precipitates to effectively hinder basal dislocation slip. As a consequence, the extruded TZA822 alloy with T4 showed a higher tensile yield strength (TYS) of 245 MPa, ultimate tensile strength (UTS) of 320 MPa and elongation (EL) of 26.5%, as well as a lower degree of yield asymmetry than their counterpart without T4. Detailed reasons for the strengthening effect were given and analyzed.

  4. Biomorphous SiC ceramics prepared from cork oak as precursor

    NASA Astrophysics Data System (ADS)

    Yukhymchuk, V. O.; Kiselov, V. S.; Valakh, M. Ya.; Tryus, M. P.; Skoryk, M. A.; Rozhin, A. G.; Kulinich, S. A.; Belyaev, A. E.

    2016-04-01

    Porous ceramic materials of SiC were synthesized from carbon matrices obtained via pyrolysis of natural cork as precursor. We propose a method for the fabrication of complex-shaped porous ceramic hardware consisting of separate parts prepared from natural cork. It is demonstrated that the thickness of the carbon-matrix walls can be increased through their impregnation with Bakelite phenolic glue solution followed by pyrolysis. This decreases the material's porosity and can be used as a way to modify its mechanical and thermal characteristics. Both the carbon matrices (resulted from the pyrolysis step) and the resultant SiC ceramics are shown to be pseudomorphous to the structure of initial cork. Depending on the synthesis temperature, 3C-SiC, 6H-SiC, or a mixture of these polytypes, could be obtained. By varying the mass ratio of initial carbon and silicon components, stoichiometric SiC or SiC:C:Si, SiC:C, and SiC:Si ceramics could be produced. The structure, as well as chemical and phase composition of the prepared materials were studied by means of Raman spectroscopy and scanning electron microscopy.

  5. Synthesis and Characterization of Tin(IV) Oxide Obtained by Chemical Vapor Deposition Method

    NASA Astrophysics Data System (ADS)

    Nagirnyak, Svitlana V.; Lutz, Victoriya A.; Dontsova, Tatiana A.; Astrelin, Igor M.

    2016-07-01

    The effect of precursors on the characteristics of tin oxide obtained by chemical vapor deposition (CVD) method was investigated. The synthesis of nanosized tin(IV) oxide was carried out with the use of two different precursors: tin(II) oxalate obtained using tin chloride(II) and oxalic acid; tin(II) oxalate obtained using tin chloride(II); and ammonium oxalate. The synthesized tin(IV) oxide samples were studied by electron microscopy, X-ray diffraction and optical spectra. The lattice parameters of tin(IV) oxide samples were defined, the bandgap of samples were calculated.

  6. Preparation of tungsten oxide

    DOEpatents

    Bulian, Christopher J [Yankton, SD; Dye, Robert C [Los Alamos, NM; Son, Steven F [Los Alamos, NM; Jorgensen, Betty S [Jemez Springs, NM; Perry, W Lee [Jemez Springs, NM

    2009-09-22

    Tungsten trioxide hydrate (WO.sub.3.H.sub.2O) was prepared from a precursor solution of ammonium paratungstate in concentrated aqueous hydrochloric acid. The precursor solution was rapidly added to water, resulting in the crash precipitation of a yellow white powder identified as WO.sub.3.H.sub.2O nanosized platelets by x-ray diffraction and scanning electron microscopy. Annealing of the powder at 200.degree. C. provided cubic phase WO.sub.3 nanopowder, and at 400.degree. C. provided WO.sub.3 nanopowder as a mixture of monoclinic and orthorhombic phases.

  7. Capability of cation exchange technology to remove proven N-nitrosodimethylamine precursors.

    PubMed

    Li, Shixiang; Zhang, Xulan; Bei, Er; Yue, Huihui; Lin, Pengfei; Wang, Jun; Zhang, Xiaojian; Chen, Chao

    2017-08-01

    N-nitrosodimethylamine (NDMA) precursors consist of a positively charged dimethylamine group and a non-polar moiety, which inspired us to develop a targeted cation exchange technology to remove NDMA precursors. In this study, we tested the removal of two representative NDMA precursors, dimethylamine (DMA) and ranitidine (RNTD), by strong acidic cation exchange resin. The results showed that pH greatly affected the exchange efficiency, with high removal (DMA>78% and RNTD>94%) observed at pHprecursor was 4. The exchange order was obtained as follows: Ca 2+ >Mg 2+ >RNTD + >K + >DMA + >NH 4 + >Na + . The partition coefficient of DMA + to Na + was 1.41±0.26, while that of RNTD + to Na + was 12.1±1.9. The pseudo second-order equation fitted the cation exchange kinetics well. Bivalent inorganic cations such as Ca 2+ were found to have a notable effect on NA precursor removal in softening column test. Besides DMA and RNTD, cation exchange process also worked well for removing other 7 model NDMA precursors. Overall, NDMA precursor removal can be an added benefit of making use of cation exchange water softening processes. Copyright © 2017. Published by Elsevier B.V.

  8. Tungsten carbide precursors as an example for influence of a binder on the particle formation in the nanosecond laser ablation of powdered materials.

    PubMed

    Holá, Markéta; Mikuska, Pavel; Hanzlíková, Renáta; Kaiser, Jozef; Kanický, Viktor

    2010-03-15

    A study of LA-ICP-MS analysis of pressed powdered tungsten carbide precursors was performed to show the advantages and problems of nanosecond laser ablation of matrix-unified samples. Five samples with different compositions were pressed into pellets both with silver powder as a binder serving to keep the matrix unified, and without any binder. The laser ablation was performed by nanosecond Nd:YAG laser working at 213 nm. The particle formation during ablation of both sets of pellets was studied using an optical aerosol spectrometer allowing the measurement of particle concentration in two size ranges (10-250 nm and 0.25-17 microm) and particle size distribution in the range of 0.25-17 microm. Additionally, the structure of the laser-generated particles was studied after their collection on a filter using a scanning electron microscope (SEM) and the particle chemical composition was determined by an energy dispersive X-ray spectroscope (EDS). The matrix effect was proved to be reduced using the same silver powdered binder for pellet preparation in the case of the laser ablation of powdered materials. The LA-ICP-MS signal dependence on the element content present in the material showed an improved correlation for Co, Ti, Ta and Nb of the matrix-unified samples compared to the non-matrix-unified pellets. In the case of W, the ICP-MS signal of matrix-unified pellets was influenced by the changes in the particle formation. Copyright (c) 2009 Elsevier B.V. All rights reserved.

  9. Determining sources of dissolved organic carbon and disinfection byproduct precursors to the McKenzie River, Oregon

    USGS Publications Warehouse

    Kraus, Tamara E.C.; Anderson, Chauncey W.; Morgenstern, Karl; Downing, Bryan D.; Pellerin, Brian A.; Bergamaschi, Brian A.

    2010-01-01

    This study was conducted to determine the main sources of dissolved organic carbon (DOC) and disinfection byproduct (DBP) precursors to the McKenzie River, Oregon (USA). Water samples collected from the mainstem, tributaries, and reservoir outflows were analyzed for DOC concentration and DBP formation potentials (trihalomethanes [THMFPs] and haloacetic acids [HAAFPs]). In addition, optical properties (absorbance and fluorescence) of dissolved organic matter (DOM) were measured to provide insight into DOM composition and assess whether optical properties are useful proxies for DOC and DBP precursor concentrations. Optical properties indicative of composition suggest that DOM in the McKenzie River mainstem was primarily allochthonous - derived from soils and plant material in the upstream watershed. Downstream tributaries had higher DOC concentrations than mainstem sites (1.6 ?? 0.4 vs. 0.7 ?? 0.3 mg L-1) but comprised <5% of mainstem flows and had minimal effect on overall DBP precursor loads. Water exiting two large upstream reservoirs also had higher DOC concentrations than the mainstem site upstream of the reservoirs, but optical data did not support in situ algal production as a source of the added DOC during the study. Results suggest that the first major rain event in the fall contributes DOM with high DBP precursor content. Although there was interference in the absorbance spectra in downstream tributary samples, fluorescence data were strongly correlated to DOC concentration (R 2 = 0.98), THMFP (R2 = 0.98), and HAAFP (R2 = 0.96). These results highlight the value of using optical measurements for identifying the concentration and sources of DBP precursors in watersheds, which will help drinking water utilities improve source water monitoring and management programs. Copyright ?? 2010 by the American Society of Agronomy.

  10. Cryopreservation of GABAergic Neuronal Precursors for Cell-Based Therapy

    PubMed Central

    2017-01-01

    Cryopreservation protocols are essential for stem cells storage in order to apply them in the clinic. Here we describe a new standardized cryopreservation protocol for GABAergic neural precursors derived from the medial glanglionic eminence (MGE), a promising source of GABAergic neuronal progenitors for cell therapy against interneuron-related pathologies. We used 10% Me2SO as cryoprotectant and assessed the effects of cell culture amplification and cellular organization, as in toto explants, neurospheres, or individualized cells, on post-thaw cell viability and retrieval. We confirmed that in toto cryopreservation of MGE explants is an optimal preservation system to keep intact the interneuron precursor properties for cell transplantation, together with a high cell viability (>80%) and yield (>70%). Post-thaw proliferation and self-renewal of the cryopreserved precursors were tested in vitro. In addition, their migration capacity, acquisition of mature neuronal morphology, and potency to differentiate into multiple interneuron subtypes were also confirmed in vivo after transplantation. The results show that the cryopreserved precursor features remained intact and were similar to those immediately transplanted after their dissection from the MGE. We hope this protocol will facilitate the generation of biobanks to obtain a permanent and reliable source of GABAergic precursors for clinical application in cell-based therapies against interneuronopathies. PMID:28122047

  11. Gamma-Ray Burst Precursor Activity as Observed with BATSE

    NASA Technical Reports Server (NTRS)

    Koshut, Thomas M.; Kouveliotou, Chryssa; Paciesas, William S.; vanParadijs, Jan; Pendleton, Geoffrey N.; Briggs, Michael S.; Fishman, Gerald J.; Meegan, Charles A.

    1995-01-01

    Gamma-ray burst time histories often consist of multiple episodes of emission with the count rate dropping to the background level between adjacent episodes. We define precursor activity as any case in which the first episode (referred to as the precursor episode) has a lower peak intensity than that of the remaining emission (referred to as the main episode) and is separated from the remaining burst emission by a background interval that is at least as long as the remaining emission. We find that approx. 3% of the bursts observed with the Burst and Transient Source Experiment (BATSE) on Compton Gamma Ray Observatory (CGRO) satisfy this definition. We present the results of a study of the properties of these events. The spatial distribution of these sources is consistent with that of the larger set of all BATSE gamma-ray bursts: inhomogeneous and isotropic. A correlation between the duration of the precursor emission and the duration of the main episode emission is observed at about the 3 sigma confidence level. We find no meaningful significant correlations between or among any of the other characteristics of the precursor or main episode emission. It appears that the characteristics of the main episode emission are independent of the existence of the precursor emission.

  12. Three-dimensionally patterned energy absorptive material and method of fabrication

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Duoss, Eric; Frank, James M.; Kuntz, Joshua

    A three-dimensionally patterned energy absorptive material and fabrication method having multiple layers of patterned filaments extrusion-formed from a curable pre-cursor material and stacked and cured in a three-dimensionally patterned architecture so that the energy absorptive material produced thereby has an engineered bulk property associated with the three-dimensionally patterned architecture.

  13. In vitro genotoxicity assessment of MTES, GPTES and TEOS, three precursors intended for use in food contact coatings.

    PubMed

    Lionti, Krystelle; Séverin, Isabelle; Dahbi, Laurence; Toury, Bérangère; Chagnon, Marie-Christine

    2014-03-01

    Organoalkoxysilanes are precursors that are used increasingly in the synthesis of food contact coatings. To comply with the EU regulation, their potential toxicity must be assessed, and very little information is known. The genotoxicity of three common precursors was studied, namely, tetraethylorthosilicate (TEOS), methyltriethoxysilane (MTES) and 3-glycidyloxypropyltriethoxysilane (GPTES). By the Ames test, MTES and TEOS were not mutagenic for bacteria. A significant positive response was observed with GPTES in the TA100 and TA1535 strains. The mutagenic effect was more pronounced in the presence of the exogenous metabolic activation system with an increase of the induction factor (ten-fold higher for the TA1535 strain). In the micronucleus assay performed with a human hepatoma cell line (HepG2 cells), GPTES gave negative results even in the presence of an exogenous activation system. To ascertain the possibility of using this precursor in food contact material, its migration must be monitored according to the coating formulation because migration might result in hazardous human exposure. Copyright © 2014. Published by Elsevier Ltd.

  14. Manganite perovskite ceramics, their precursors and methods for forming

    DOEpatents

    Payne, David Alan; Clothier, Brent Allen

    2015-03-10

    Disclosed are a variety of ceramics having the formula Ln.sub.1-xM.sub.xMnO.sub.3, where 0.Itoreq.x.Itoreq.1 and where Ln is La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu or Y; M is Ca, Sr, Ba, Cd, or Pb; manganite precursors for preparing the ceramics; a method for preparing the precursors; and a method for transforming the precursors into uniform, defect-free ceramics having magnetoresistance properties. The manganite precursors contain a sol and are derived from the metal alkoxides: Ln(OR).sub.3, M(OR).sub.2 and Mn(OR).sub.2, where R is C.sub.2 to C.sub.6 alkyl or C.sub.3 to C.sub.9 alkoxyalkyl, or C.sub.6 to C.sub.9 aryl. The preferred ceramics are films prepared by a spin coating method and are particularly suited for incorporation into a device such as an integrated circuit device.

  15. Flagellar filament bio-templated inorganic oxide materials - towards an efficient lithium battery anode

    NASA Astrophysics Data System (ADS)

    Beznosov, Sergei N.; Veluri, Pavan S.; Pyatibratov, Mikhail G.; Chatterjee, Abhijit; Macfarlane, Douglas R.; Fedorov, Oleg V.; Mitra, Sagar

    2015-01-01

    Designing a new generation of energy-intensive and sustainable electrode materials for batteries to power a variety of applications is an imperative task. The use of biomaterials as a nanosized structural template for these materials has the potential to produce hitherto unachievable structures. In this report, we have used genetically modified flagellar filaments of the extremely halophilic archaea species Halobacterium salinarum to synthesize nanostructured iron oxide composites for use as a lithium-ion battery anode. The electrode demonstrated a superior electrochemical performance compared to existing literature results, with good capacity retention of 1032 mAh g-1 after 50 cycles and with high rate capability, delivering 770 mAh g-1 at 5 A g-1 (~5 C) discharge rate. This unique flagellar filament based template has the potential to provide access to other highly structured advanced energy materials in the future.

  16. Improved Single-Source Precursors for Solar-Cell Absorbers

    NASA Technical Reports Server (NTRS)

    Banger, Kulbinder K.; Harris, Jerry; Hepp, Aloysius

    2007-01-01

    Improved single-source precursor compounds have been invented for use in spray chemical vapor deposition (spray CVD) of chalcopyrite semiconductor absorber layers of thin-film cells. A "single-source precursor compound" is a single molecular compound that contains all the required elements, which when used under the spray CVD conditions, thermally decomposes to form CuIn(x)Ga(1-x)S(y)Se(2-y).

  17. Whole-cell fungal transformation of precursors into dyes

    PubMed Central

    2010-01-01

    Background Chemical methods of producing dyes involve extreme temperatures and unsafe toxic compounds. Application of oxidizing enzymes obtained from fungal species, for example laccase, is an alternative to chemical synthesis of dyes. Laccase can be replaced by fungal biomass acting as a whole-cell biocatalyst with properties comparable to the isolated form of the enzyme. The application of the whole-cell system simplifies the transformation process and reduces the time required for its completion. In the present work, four fungal strains with a well-known ability to produce laccase were tested for oxidation of 17 phenolic and non-phenolic precursors into stable and non-toxic dyes. Results An agar-plate screening test of the organic precursors was carried out using four fungal strains: Trametes versicolor, Fomes fomentarius, Abortiporus biennis, and Cerrena unicolor. Out of 17 precursors, nine were transformed into coloured substances in the presence of actively growing fungal mycelium. The immobilized fungal biomass catalyzed the transformation of 1 mM benzene and naphthalene derivatives in liquid cultures yielding stable and non-toxic products with good dyeing properties. The type of fungal strain had a large influence on the absorbance of the coloured products obtained after 48-hour transformation of the selected precursors, and the most effective was Fomes fomentarius (FF25). Whole-cell transformation of AHBS (3-amino-4-hydroxybenzenesulfonic acid) into a phenoxazinone dye was carried out in four different systems: in aqueous media comprising low amounts of carbon and nitrogen source, in buffer, and in distilled water. Conclusions This study demonstrated the ability of four fungal strains belonging to the ecological type of white rot fungi to transform precursors into dyes. This paper highlights the potential of fungal biomass for replacing isolated enzymes as a cheaper industrial-grade biocatalyst for the synthesis of dyes and other commercially important

  18. Nanosized CuO and ZnO catalyst supported on titanium chip for conversion of carbon dioxide to methyl alcohol.

    PubMed

    Seo, Hyeong-Seok; Park, Chul-Min; Kim, Ki-Joong; Jeong, Woon-Jo; Chung, Min-Chul; Jung, Sang-Chul; Kim, Sang-Chai; Ahn, Ho-Geun

    2013-08-01

    In order to reutilize spent metallic titanium chips (TC) as catalyst support or photocatalytic materials, the surface of the TC was modified by thermal treatment under air atmosphere. TC-supported nanosized CuO and ZnO catalysts were prepared by impregnation (IMP) and co-precipitation (CP) method, respectively. The catalytic activity for CO2 hydrogenation to CH3OH was investigated using a flow-typed reactor under various reaction pressures. The crystals of CuO and ZnO was well formed on TC. CO2 conversion, CH3OH selectivity, and CH3OH yield were obtained as a function of time on stream over CuO-ZnO/TC catalysts. Conversion of CO2 to CH3OH over CuO-ZnO/TC catalyst by CP method and CuO/ZnO/TC catalyst by IMP method were ca. 16% and ca. 12%, respectively. Conversion of CO2 over CuO-ZnO/TC catalyst by CP method was increased with increasing reaction temperature in the range of 15-30 atm. Maximum selectivity and yield to CH3OH over CuO-ZnO/TC at 250 degrees C were ca. 90% at 20 atm and ca. 18.2% at 30 atm, respectively.

  19. Structural Transitions in Nanosized Zn0.97Al0.03O Powders under High Pressure Analyzed by in Situ Angle-Dispersive X-ray Diffraction

    PubMed Central

    Lin, Chih-Ming; Liu, Hsin-Tzu; Zhong, Shi-Yao; Hsu, Chia-Hung; Chiu, Yi-Te; Tai, Ming-Fong; Juang, Jenh-Yih; Chuang, Yu-Chun; Liao, Yen-Fa

    2016-01-01

    Nanosized aluminum-doped zinc oxide Zn1−xAlxO (AZO) powders (AZO-NPs) with x = 0.01, 0.03, 0.06, 0.09 and 0.11 were synthesized by chemical precipitation method. The thermogravimetric analysis (TGA) indicated that the precursors were converted to oxides from hydroxides near 250 °C, which were then heated to 500 °C for subsequent thermal processes to obtain preliminary powders. The obtained preliminary powders were then calcined at 500 °C for three hours. The structure and morphology of the products were measured and characterized by angle-dispersive X-ray diffraction (ADXRD) and scanning electron microscopy (SEM). ADXRD results showed that AZO-NPs with Al content less than 11% exhibited würtzite zinc oxide structure and there was no other impurity phase in the AZO-NPs, suggesting substitutional doping of Al on Zn sites. The Zn0.97Al0.03O powders (A3ZO-NPs) with grain size of about 21.4 nm were used for high-pressure measurements. The in situ ADXRD measurements revealed that, for loading run, the pressure-induced würtzite (B4)-to-rocksalt (B1) structural phase transition began at 9.0(1) GPa. Compared to the predicted phase-transition pressure of ~12.7 GPa for pristine ZnO nanocrystals of similar grain size (~21.4 nm), the transition pressure for the present A3ZO-NPs exhibited a reduction of ~3.7 GPa. The significant reduction in phase-transition pressure is attributed to the effects of highly selective site occupation, namely Zn2+ and Al3+, were mainly found in tetrahedral and octahedral sites, respectively. PMID:28773683

  20. Reconstruction of Mini-Hollow Polyhedron Mn2O3 Derived from MOFs as a High-Performance Lithium Anode Material.

    PubMed

    Cao, Kangzhe; Jiao, Lifang; Xu, Hang; Liu, Huiqiao; Kang, Hongyan; Zhao, Yan; Liu, Yongchang; Wang, Yijing; Yuan, Huatang

    2016-03-01

    A mini-hollow polyhedron Mn 2 O 3 is used as the anode material for lithium-ion batteries. Benefiting from the small interior cavity and intrinsic nanosize effect, a stable reconstructed hierarchical nanostructure is formed. It has excellent energy storage properties, exhibiting a capacity of 760 mAh g -1 at 2 A g -1 after 1000 cycles. This finding offers a new perspective for the design of electrodes with large energy storage.