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1

Combustion synthesis and nanomaterials  

Microsoft Academic Search

The recent developments and trends in combustion science towards the synthesis of nanomaterials are discussed. Different modifications made to conventional combustion approaches for preparation of nanomaterials are critically analyzed. Special attention is paid to various applications of combustion synthesized nanosized products.

Singanahally T. Aruna; Alexander S. Mukasyan

2008-01-01

2

Mechanical-activation-assisted combustion synthesis of {alpha}-SiAlON in air  

SciTech Connect

With the assistance of mechanical activation, yttrium-stabilized {alpha}-SiAlON was prepared by combustion synthesis in air, instead of high-pressure N{sub 2} atmosphere for the first time. The reaction activity of metallic particles was remarkably enhanced by mechanical activation, which conduced the reduction of grain size, increased the total surface area and formation of fresh surface. The formation of {alpha}-SiAlON by combustion synthesis in air was explained by a kinetically induced reaction mechanism, in which both initial formation of {alpha}-SiAlON and following avoidance of oxidation were fulfilled by the retardation of O{sub 2} infiltration owing to the short reaction period and fast cooling rate.

Liu Guanghua [Department of Materials Science and Engineering, State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University, 100084 Beijing (China); Chen Kexin [Department of Materials Science and Engineering, State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University, 100084 Beijing (China)]. E-mail: kxchen@mail.tsinghua.edu.cn; Zhou Heping [Department of Materials Science and Engineering, State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University, 100084 Beijing (China); Li Jiangtao [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, 100101 Beijing (China); Pereira, C. [Department of Ceramics and Glass Engineering, University of Aveiro, CICECO, 3810-193 Aveiro (Portugal); Ferreira, J.M.F. [Department of Ceramics and Glass Engineering, University of Aveiro, CICECO, 3810-193 Aveiro (Portugal)

2007-06-05

3

Electric Current Activated Combustion Synthesis and Chemical Ovens Under Terrestrial and Reduced Gravity Conditions  

NASA Technical Reports Server (NTRS)

Combustion synthesis (CS) generally involves mixing reactants together (e.g., metal powders) and igniting the mixture. Typically, a reaction wave will pass through the sample. In field activated combustion synthesis (FACS), the addition of an electric field has a marked effect on the dynamics of wave propagation and on the nature, composition, and homogeneity of the product as well as capillary flow, mass-transport in porous media, and Marangoni flows, which are influenced by gravity. The objective is to understand the role of an electric field in CS reactions under conditions where gravity-related effects are suppressed or altered. The systems being studied are Ti+Al and Ti+3Al. Two different ignition orientations have been used to observe effects of gravity when one of the reactants becomes molten. This consequentially influences the position and concentration of the electric current, which in turn influences the entire process. Experiments have also been performed in microgravity conditions. This process has been named Microgravity Field Activated Combustion Synthesis (MFACS). Effects of gravity have been demonstrated, where the reaction wave temperature and velocity demonstrate considerable differences besides the changes of combustion mechanisms with the different high currents applied. Also the threshold for the formation of a stable reaction wave is increased under zero gravity conditions. Electric current was also utilized with a chemical oven technique, where inserts of aluminum with minute amounts of tungsten and tantalum were used to allow observation of effects of settling of the higher density solid particles in liquid aluminum at the present temperature profile and wave velocity of the reaction.

Unuvar, C.; Fredrick, D.; Anselmi-Tamburini, U.; Manerbino, A.; Guigne, J. Y.; Munir, Z. A.; Shaw, B. D.

2004-01-01

4

Synthesis of Highly Active Mg-BASED Hydrides Using Hydriding Combustion Synthesis and NbF5 Additives  

NASA Astrophysics Data System (ADS)

Superiority of the hydriding combustion (HC) technique over conventional metallurgical approach to the synthesis of cost-effective Mg based hydrides, which show promise as hydrogen storage materials, is well known. In the present research, we report further improvements in HC prepared Mg-based materials, achieved by optimizing the preparative parameters of HC and by catalytic addition. Mg90-Ni60-C40 composites prepared using optimized processing parameters were ball-milled with NbF5 (10 h) and characterized for their micro-structural and hydriding properties. The ball-milled/catalyzed powder showed decreased crystallinity with CNTs on its surfaces. Surface area of the ball-milled powder decreased to almost half of the as-HC powder, while TG analysis revealed a four-fold decrease in the desorption temperature of the milled powder compared to that of the as-HC prepared powder. Activated samples achieved the maximum absorption/desorption limits (5.3 wt.%) at as low as 100°C, underlining the possibility of the use of these materials in portable hydrogen storage devices.

Chourashiya, M. G.; Park, C. N.; Park, C. J.

2012-09-01

5

Combustion synthesis of complex oxides  

Microsoft Academic Search

Advanced ceramic materials have numerous applications in electronic engineering, chemical engineering, and semiconductor industry. The synthesis of these materials at an economical cost is the bottleneck in the application of these materials. Self-propagating High-temperature Synthesis (SHS) is a new technique for producing these materials for exothermic systems by a combustion wave that propagates and produces high purity products. The full

Qimin Ming

1999-01-01

6

Combustion synthesis method and products  

DOEpatents

Disclosed is a method of producing dense refractory products, comprising: (a) obtaining a quantity of exoergic material in powder form capable of sustaining a combustion synthesis reaction; (b) removing absorbed water vapor therefrom; (c) cold-pressing said material into a formed body; (d) plasma spraying said formed body with a molten exoergic material to form a coat thereon; and (e) igniting said exoergic coated formed body under an inert gas atmosphere and pressure to produce self-sustained combustion synthesis. Also disclosed are products produced by the method.

Holt, J.B.; Kelly, M.

1993-03-30

7

Combustion synthesis method and products  

DOEpatents

Disclosed is a method of producing dense refractory products, comprising: (a) obtaining a quantity of exoergic material in powder form capable of sustaining a combustion synthesis reaction; (b) removing absorbed water vapor therefrom; (c) cold-pressing said material into a formed body; (d) plasma spraying said formed body with a molten exoergic material to form a coat thereon; and (e) igniting said exoergic coated formed body under an inert gas atmosphere and pressure to produce self-sustained combustion synthesis. Also disclosed are products produced by the method.

Holt, J. Birch (San Jose, CA); Kelly, Michael (West Alexandria, OH)

1993-01-01

8

Combustion Synthesis of Nanostructures  

NASA Astrophysics Data System (ADS)

Novel carbon and inorganic 1D nanostructures were prepared by combustion of metal-polytetrafluoroethylene (PTFE) systems in a calorimetric bomb. The high carbon yield from silicon-containing PTFE starting materials is due to the production and volatility of SiF4.

Huczko, A.; Lange, H.; Chojecki, G.; Cudzi??o, S.; Zhu, Y. Q.; Walton, D. R. M.; Kroto, H. W.; Presz, A.; Diduszko, R.

2002-10-01

9

Hydriding combustion synthesis of TiFe  

Microsoft Academic Search

Titanium iron (TiFe) is one of the most attractive metal hydrides because of abundant and low cost raw materials and moderate conditions for hydrogenation and dehydrogenation; however, it has not been practically used due to time-consuming and energy-consuming activation treatment. Aiming to improve the initial activity of TiFe, we applied hydriding combustion synthesis (HCS), which has attractive advantages for the

I. Saita; M. Sato; H. Uesugi; T. Akiyama

2007-01-01

10

Novel approaches to solution-combustion synthesis of nanomaterials  

Microsoft Academic Search

Solution-combustion is an attractive approach to synthesis of nanomaterials for a variety of applications, including catalysts,\\u000a fuel cells, and biotechnology. In this paper, several novel methods based on the combustion of a reactive solution are presented.\\u000a These methods include self-propagating sol-gel combustion and combustion of impregnated inert and active supports. It was\\u000a demonstrated that, based on the fundamental understanding of

A. S. Mukasyan; P. Dinka

2007-01-01

11

Combustion Synthesis of Magnesium Aluminate  

SciTech Connect

In the system MgO-Al{sub 2}O{sub 3}, three compounds MgAl{sub 2}O{sub 4}, MgAl{sub 6}O{sub 10}(also expressed as-Mg{sub 0.4}Al{sub 2.4}O{sub 4}) and MgAl{sub 26}O{sub 40} are well known. Importance of the first two is well established. Magnesium aluminate (MgAl{sub 2}O{sub 4}) spinel is a technologically important material due to its interesting thermal properties. The MgAl{sub 2}O{sub 4} ceramics also find application as humidity sensors. Apart from the luminescence studies, the interest in MgAl{sub 2}O{sub 4} is due to various applications such as humidity-sensing and PEM fuel cells, TL/OSL dosimetry of the ionizing radiations, white light source. Interest in the MgAl{sub 6}O{sub 10} has aroused due to possible use as a substrate for GaN growth. Attempt was made to synthesize these compounds by the combustion synthesis using metal nitrates as oxidizer and urea as a fuel. Compounds MgAl{sub 2}O{sub 4} and MgAl{sub 6}O{sub 10} were formed in a single step, while MgAl{sub 26}O{sub 40} was not formed by this procedure. Activation of MgAl{sub 6}O{sub 10} by rare earth ions like Ce{sup 3+}, Eu{sup 3+} and Tb{sup 3+} and ns{sup 2} ion Pb{sup 2+} could be achieved. Excitation bands for MgAl{sub 6}O{sub 10} are at slightly shorter wavelengths compared to those reported for MgAl{sub 2}O{sub 4}.

Kale, M. A. [Physics Department, S.V.S.S. College of Engineering and Research, Nagpur 4411 10 (India); Joshi, C. P. [Physics Department, Ramdeobaba Engineering College, Katol Road, Nagpur 440 013 (India); Moharil, S. V. [Physics Department, RTM Nagpur University, Nagpur, 440033 (India)

2011-10-20

12

Gravity Effects on Combustion Synthesis of Glasses  

NASA Technical Reports Server (NTRS)

The Combustion Synthesis technique has been used to produce glasses based on B2O3-Al2O3-MgO and CaO-Al2O3. The combustion characteristics of these combustion synthesis reactions using both small cylindrical pellets (SCP) and large spherical pellets (LSP) are presented. Low density pellets (approx. 35% of their theoretical density) were used, which made synthesis of low exothermic combustion reactions possible. Microstructural analysis of reacted samples was carried out to identify the glass-forming compositions. The effects of gravity on the glass formation were studied aboard the KC-135 using SCP samples. Gravity seemed to have such obvious effects on the combustion characteristics that the wave velocity was lower and the Width of the combustion wave was larger under reduced gravity conditions. Samples produced under low gravity also had more enhanced vitrification than those on ground, while some systems also exhibited lower combustion temperatures. It was also found that the container significantly affects both the combustion characteristics and microstructure. Substantially more divitrification occurred at the area which was in contact with the support (container).

Yi, H. C.; Guigne, J. Y.; Moore, J. J.; Robinson, L. A.; Manerbino, A. R.; Schowengerdt, F. D.; Gokoglu, S. (Technical Monitor)

2000-01-01

13

Combustion synthesis of YAG:Ce and related phosphors  

NASA Astrophysics Data System (ADS)

YAG:Ce is an important phosphor having applications in various fields ranging from solid state lighting to scintillation detectors. YAG phosphors doped with activators are mainly synthesized by solid state reaction techniques that require high sintering temperatures (above 1500°C) to eliminate YAM and YAP phases. Though several soft chemical routes have been explored for synthesis of YAG, most of these methods are complex and phase pure materials are not obtained in one step, but prolonged annealing at temperatures around 1000°C or above become necessary. One step combustion synthesis of YAG:Ce3+ and related phosphors carried out at 500°C furnace temperature is reported here. Activation with Ce3+ could be achieved during the synthesis without taking recourse to any post-combustion thermal treatment. LEDs prepared from the combustion synthesized YAG:Ce3+, exhibited properties comparable to those produced from the commercial phosphor.

Gupta, K. V. K.; Muley, A.; Yadav, P.; Joshi, C. P.; Moharil, S. V.

2011-11-01

14

Combustion and Plasma Synthesis of High-Temperature Materials  

NASA Astrophysics Data System (ADS)

KEYNOTE ADDRESS. Self-Propagating High-Temperature Synthesis: Twenty Years of Search and Findings (A. Merzhanov). SOLID-STATE COMBUSTION SYNTHESIS. Recent Progress in Combustion Synthesis of High-Performance Materials in Japan (M. Koizumi & Y. Miyamoto). Modeling and Numerical Computation of a Nonsteady SHS Process (A. Bayliss & B. Matkowsky). New Models of Quasiperiodic Burning in Combustion Synthesis (S. Margolis, et al.). Modeling of SHS Operations (V. Hlavacek, et al.). Combustion Theory for Sandwiches of Alloyable Materials (R. Armstrong & M. Koszykowski). Observations on the Combustion Reaction Between Thin Foils of Ni and Al (U. Anselmi-Tamburini & Z. Munir). Combustion Synthesis of Intermetallic Compounds (Y. Kaieda, et al.). Combustion Synthesis of Nickel Aluminides (B. Rabin, et al.). Self-Propagating High-Temperature Synthesis of NiTi Intermetallics (H. Yi & J. Moore). Shock-Induced Chemical Synthesis of Intermetallic Compounds (S. Work, et al.). Advanced Ceramics Via SHS (T. DeAngelis & D. Weiss). In-Situ Formation of SiC and SiC-C Blocked Solids by Self-Combustion Synthesis (S. Ikeda, et al.). Powder Purity and Morphology Effects in Combustion-Synthesis Reactions (L. Kecskes, et al.). Simultaneous Synthesis and Densification of Ceramic Components Under Gas Pressure by SHS (Y. Miyamoto & M. Koizumi). The Use of Self-Propagating High-Temperature Synthesis of High-Density Titanium Diboride (P. Zavitsanos, et al.). Metal--Ceramic Composite Pipes Produced by a Centrifugal-Thermit Process (O. Odawara). Simultaneous Combustion Synthesis and Densification of AIN (S. Dunmead, et al.). Fabrication of a Functionally Gradient Material by Using a Self-Propagating Reaction Process (N. Sata, et al.). Combustion Synthesis of Oxide-Carbide Composites (L. Wang, et al.). Heterogeneous Reaction Mechanisms in the Si-C System Under Conditions of Solid Combustion (R. Pampuch, et al.). Experimental Modeling of Particle-Particle Interactions During SHS of TiB2 -Al2O3 (K. Logan, et al.). Combustion Synthesis in the Ti-C-Ni-Al System (S. Dunmead, et al.). Combustion Synthesis Dynamics Modeling (T. Kottke, et al.). Elementary Processes in SiO2-Al Thermite-Type Reactions Activated or Induced by Mechanochemical Treatment (G. Hida & I. Lin). Combustion Synthesis of Ceramic Preforms for Molten-Metal Infiltration (D. Halverson, et al.). Combustion Characteristics of Solid-Solid Systems: Experiments and Modeling (S. Kumar, et al.). Microstructure of TiB2 Sintered by the Self-Combustion Method (K. Urabe, et al..). A Laser-Ignition Study of Gasless Reactions Using Thermography (C. Chow & J. Mohler). Shock-Induced Reaction Synthesis-Assisted Processing of Ceramics (R. Ward, et al.). Summary Assessment of the Application of SPS and Related Reaction Processing to Produce Dense Ceramics (R. Rice). Shock Consolidation of Combustion-Synthesized Ceramics (A. Niiler, et al.). High-Pressure Burning Rate of Silicon in Nitrogen (M. Costantino & J. Holt). Preparation of a TiC Single Crystal by the Floating-Zone Method from a Self-Combustion Rod (S. Otani, et al.). PLASMA AND GAS-PHASE SYNTHESIS. Thermal Plasma Synthesis of Ceramic Powders and Coatings (T. Yoshida). A Theoretical Comparison of Conventional and Hybrid RF-Plasma Reactors (J. McKelliget & N. El-Kaddah). Homogeneous Nucleation and Particle Growth in Thermal Plasma Synthesis (S. Girshick & C.-P. Chiu). Formation of Refractory Aerosol Particles (R. Flagan, et al.). Ceramic-Powder Synthesis in an Aerosol Reactor (M. Alam, et al.). Silica-Particle Formation Using the Counter-Flow Diffusion Flame Burner (J. Katz, et al.). Synthesis and Properties of Low-Carbon Boron Carbides (C. Adkins, et al.). Synthesis of Si, SiC, and Si3N4 Powders Under High Number Density Conditions (J. Haggerty & J. Flint). Rapid Preparation of Titanium and Other Transition-Metal Nitride- and Carbide Powders by a Carbo-Reduction Method Using Arc-Image Heating (M. Yoshimura, et al.). Microwave Plasma Densification of Aluminum Nitride (S. Knittel & S. Risbud). Plasma Synth

Munir, Z. A.; Holt, J. B.

1997-04-01

15

Combustion and Plasma Synthesis of High-Temperature Materials  

Microsoft Academic Search

KEYNOTE ADDRESS. Self-Propagating High-Temperature Synthesis: Twenty Years of Search and Findings (A. Merzhanov). SOLID-STATE COMBUSTION SYNTHESIS. Recent Progress in Combustion Synthesis of High-Performance Materials in Japan (M. Koizumi & Y. Miyamoto). Modeling and Numerical Computation of a Nonsteady SHS Process (A. Bayliss & B. Matkowsky). New Models of Quasiperiodic Burning in Combustion Synthesis (S. Margolis, et al.). Modeling of SHS

Z. A. Munir; J. B. Holt

1997-01-01

16

Reaction mechanism of combustion synthesis of NiAl  

Microsoft Academic Search

Based on precise temperature measurements during combustion and microstructural analysis of quenched samples, the evolution of reaction of the NiAl combustion synthesis has been studied. The combustion reaction of a multilayer Ni\\/Al system takes place in a thermal explosion mode under near adiabatic conditions. The experimental results clearly show that the combustion reaction starts right after the melting of Al.

Ping Zhu; J. C. M Li; C. T Liu

2002-01-01

17

Combustion synthesis of boride and other composites  

Microsoft Academic Search

This patent describes a self-sustaining combustion synthesis process for producing hard, tough, lightweight BâC\\/TiBâ composites. It is based on the thermodynamic dependence of adiabatic temperature and product composition on the stoichiometry of the BâC and TiBâ reactants. For lightweight products the composition must be relatively rich in the BâC component. BâC-rich composites are obtained by varying the initial temperature of

D. C. Halverson; B. Y. Lum; Z. A. Munir

1989-01-01

18

Combustion synthesis of boride and other composites  

Microsoft Academic Search

A self-sustaining combustion synthesis process for producing hard, tough, lightweight BâC\\/TiBâ composites is described. It is based on the thermodynamic dependence of adiabatic temperature and product composition on the stoichiometry of the BâC and TiBâ reactants. For lightweight products the composition must be relatively rich in the BâC component. BâC-rich composites are obtained by varying the initial temperature of the

D. C. Halverson; B. Y. Lum; Z. A. Munir

1988-01-01

19

Combustion synthesis of boride and other composites  

Microsoft Academic Search

A self-sustaining combustion synthesis process for producing hard, tough, lightweight B.sub.4 C\\/TiB.sub.2 composites is based on the thermodynamic dependence of adiabatic temperature and product composition on the stoichiometry of the B.sub.4 C and TiB.sub.2 reactants. For lightweight products the composition must be relatively rich in the B.sub.4 C component. B.sub.4 C-rich composites are obtained by varying the initial temperature of

Danny C. Halverson; Beverly Y. Lum; Zuhair A. Munir

1989-01-01

20

Combustion synthesis of titanium carbide: Theory and experiment  

Microsoft Academic Search

The combustion synthesis of titanium carbide from elemental powders has been theoretically and experimentally studied as a model system for self -propagating high temperature synthesis (SHS) of refractory compounds. Calculations of the adiabatic temperature of combustion of graphite and titanium powders to form TiCx have been made to show the effects of stoichiometry, dilution and the initial temperature of the

J. B. Holt; Z. A. Munir

1986-01-01

21

Demonstration of Active Combustion Control  

NASA Technical Reports Server (NTRS)

The primary objective of this effort was to demonstrate active control of combustion instabilities in a direct-injection gas turbine combustor that accurately simulates engine operating conditions and reproduces an engine-type instability. This report documents the second phase of a two-phase effort. The first phase involved the analysis of an instability observed in a developmental aeroengine and the design of a single-nozzle test rig to replicate that phenomenon. This was successfully completed in 2001 and is documented in the Phase I report. This second phase was directed toward demonstration of active control strategies to mitigate this instability and thereby demonstrate the viability of active control for aircraft engine combustors. This involved development of high-speed actuator technology, testing and analysis of how the actuation system was integrated with the combustion system, control algorithm development, and demonstration testing in the single-nozzle test rig. A 30 percent reduction in the amplitude of the high-frequency (570 Hz) instability was achieved using actuation systems and control algorithms developed within this effort. Even larger reductions were shown with a low-frequency (270 Hz) instability. This represents a unique achievement in the development and practical demonstration of active combustion control systems for gas turbine applications.

Lovett, Jeffrey A.; Teerlinck, Karen A.; Cohen, Jeffrey M.

2008-01-01

22

Reverse microemulsion synthesis of nanostructured complex oxides for catalytic combustion  

PubMed

Catalysts play an important role in many industrial processes, but their use in high-temperature applications-such as energy generation through natural gas combustion, steam reforming and the partial oxidation of hydrocarbons to produce feedstock chemicals--is problematic. The need for catalytic materials that remain stable and active over long periods at high operation temperatures, often in the presence of deactivating or even poisoning compounds, presents a challenge. For example, catalytic methane combustion, which generates power with reduced greenhouse-gas and nitrogen-oxide emissions, is limited by the availability of catalysts that are sufficiently active at low temperatures for start-up and are then able to sustain activity and mechanical integrity at flame temperatures as high as 1,300 degrees C. Here we use sol-gel processing in reverse microemulsions to produce discrete barium hexa-aluminate nanoparticles that display excellent methane combustion activity, owing to their high surface area, high thermal stability and the ultrahigh dispersion of cerium oxide on the their surfaces. Our synthesis method provides a general route to the production of a wide range of thermally stable nanostructured composite materials with large surface-to-volume ratios and an ultrahigh component dispersion that gives rise to synergistic chemical and electronic effects, thus paving the way to the development of catalysts suitable for high-temperature industrial applications. PMID:10638751

Zarur; Ying

2000-01-01

23

Combustion synthesis of boride and other composites  

DOEpatents

A self-sustaining combustion synthesis process for producing hard, tough, lightweight B.sub.4 C/TiB.sub.2 composites is based on the thermodynamic dependence of adiabatic temperature and product composition on the stoichiometry of the B.sub.4 C and TiB.sub.2 reactants. For lightweight products the composition must be relatively rich in the B.sub.4 C component. B.sub.4 C-rich composites are obtained by varying the initial temperature of the reactants. The product is hard, porous material whose toughness can be enhanced by filling the pores with aluminum or other metal phases using a liquid metal infiltration process. The process can be extended to the formation of other composites having a low exothermic component.

Halverson, Danny C. (Modesto, CA); Lum, Beverly Y. (Livermore, CA); Munir, Zuhair A. (Davis, CA)

1989-01-01

24

Combustion synthesis of boride and other composites  

DOEpatents

A self-sustaining combustion synthesis process for producing hard, tough, lightweight B/sub 4/C/TiB/sub 2/ composites is described. It is based on the thermodynamic dependence of adiabatic temperature and product composition on the stoichiometry of the B/sub 4/C and TiB/sub 2/ reactants. For lightweight products the composition must be relatively rich in the B/sub 4/C component. B/sub 4/C-rich composites are obtained by varying the initial temperature of the reactants. The product is hard, porous material whose toughness can be enhanced by filling the pores with aluminum or other metal phases using a liquid metal infiltration process. The process can be extended to the formation of other composites having a low exothermic component. 9 figs., 4 tabs.

Halverson, D.C.; Lum, B.Y.; Munir, Z.A.

1988-07-28

25

Activated combustion features in the Mo-Si-C-promoter system and synthesis of MoSi{sub 2}-SiC composite powders  

SciTech Connect

Opportunities on combustion synthesizing the MoSi{sub 2}-SiC ceramic composites in a wide range of compositions under the chemical activated mode were studied. Molybdenum, silicon powders and carbon black were used as initial reagents, and Teflon was used as an activating additive. It was established that Teflon displays a dual (kinetic and thermal) impact on the interaction between reagents. The phasic character of the combustion process evolution, being characterized by low- and high-temperature regimes, was revealed. The end-products were subjected to SEM, XRD and chemical analyses.

Hambartsumyan, A.A. [Laboratory of Kinetics of SHS Processes, A.B. Nalbandyan Institute of Chemical Physics, National Academy of Sciences, P. Sevak str. 5/2, Yerevan 0014 (Armenia); Khachatryan, H.L. [Department of Chemical Physics, Yerevan State University, A. Manukyan str. 1, Yerevan 0025 (Armenia)], E-mail: hayk@ichph.sci.am; Harutyunyan, A.B. [Laboratory of Kinetics of SHS Processes, A.B. Nalbandyan Institute of Chemical Physics, National Academy of Sciences, P. Sevak str. 5/2, Yerevan 0014 (Armenia); Kharatyan, S.L. [Laboratory of Kinetics of SHS Processes, A.B. Nalbandyan Institute of Chemical Physics, National Academy of Sciences, P. Sevak str. 5/2, Yerevan 0014 (Armenia); Department of Chemical Physics, Yerevan State University, A. Manukyan str. 1, Yerevan 0025 (Armenia)

2007-12-04

26

Synthesis of zeolite phases from combustion by-products.  

PubMed

Synthesis of zeolites from combustion by-products, including fly ash, bottom ash and rice husk ash, was studied. A molar ratio of SiO2/Al2O3 of 1.5 was used for the syntheses. Refluxing and hydrothermal methods were also used for synthesis for comparison. The reaction temperatures of refluxing and hydrothermal methods were 100 degrees C and 130 degrees C, respectively. Sodalite, phillipsite-K, and zeolite P1 with analcime were obtained when fly ash, bottom ash and rice husk ash were used as starting materials, respectively. With rice husk ash as a starting material, zeolite P1 was produced. This result had advantages over previous studies as there was no prior activation required for the synthesis. The concentrations and types of alkaline used in the synthesis also determined the zeolite type. The different zeolites obtained from three systems were measured for specific surface area and pore size by using BET and Hg-porosimetry, respectively. Ammonium exchange capacities of the synthesised powders containing zeolites, sodalite, zeolite P1 and phillipsite-K were 38.5, 65.0 and 154.7 meq 100 g(-1), respectively. PMID:20421244

Pimraksa, Kedsarin; Chindaprasirt, Prinya; Setthaya, Naruemon

2010-12-01

27

The solution combustion synthesis of nanophosphors  

SciTech Connect

Nanophosphors are defined as nano-sized (1-100mn), insulating, inorganic materials that emit light under particle or electromagnetic excitation. Their unique luminescence properties provide an excellent potential for applications in radiation detection and imaging. Herein, solution combustion synthesis (SCS) is presented as a method to prepare nanophosphor powders, while X-ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence (PL), photoluminescence excitation (PLE), and other techniques were used to characterize their structural and optical properties. The goal of this work is to synthesize bright, high-quality powders of nanophosphors, consolidate them into bulk materials and study their structural and optical properties using XRD, TEM, PL, and PLE. SCS is of interest because it is a robust, inexpensive, and facile technique, which yields a significant amount of a wide variety of oxide materials, in a short amount of time. Several practical nanophosphors were synthesized and investigated in this work, including simple oxides such as Y{sub 2}O{sub 3}:Bi, Y{sub 2}O{sub 3}:Tb, Y{sub 2}O{sub 3}:Eu and Gd{sub 2}O{sub 3}:Eu, complex oxides such as Gd{sub 2}SiO{sub 5}:Ce, Y{sub 2}SiO{sub 5}:Ce, Lu{sub 2}SiO{sub 5}:Ce, Zn{sub 2}SiO{sub 4}:Mn, and Y{sub 3}Al{sub 5}O{sub 12}:Ce. Results demonstrate that altering the processing parameters such as water content of the precursor solution, ignition temperature, fuel type and amount, and post-synthesis annealing can significantly improve light output, and that it is possible to optimize the luminescence output of oxyorthosilicates by reducing the amount of silica in the precursor mixture.

Tornga, Stephanie C [Los Alamos National Laboratory

2009-01-01

28

The combustion synthesis of multilayer NiAl systems  

Microsoft Academic Search

The synthesis of materials by combustion methods, including the self-propagating high-temperature synthesis (SHS) method, involves, typically, the use of powders as reactant materials. The use of particulate materials gives rise to difficulties in experimental and theoretical studies. In the former, the use of powders can result in the introduction of impurities associated with the surface films on the powders. Attempts

T. S. Dyer; Z. A. Munir; V. Ruth

1994-01-01

29

Combustion of mechanically activated 3Ti + 2BN mixtures  

Microsoft Academic Search

Laws of self-propagating high-temperature synthesis in 3Ti + 2BN reactive mixtures after preliminary mechanical activation\\u000a in a planetary ball mill are studied. A discontinuity caused by specific features of the dynamics of formation of mechanocomposites\\u000a is observed on the plots of the burning rate and temperature versus time. Regimes of preliminary activation are determined,\\u000a which ensure the solid-phase combustion regime.

M. A. Korchagin; B. B. Bokhonov

2010-01-01

30

One Step Combustion Synthesis Of YAG:Ce Phosphor For Solid State Lighting  

NASA Astrophysics Data System (ADS)

YAG:Ce is an important phosphor having applications in various fields ranging from solid state lighting to scintillation detectors. YAG phosphors doped with activators are mainly synthesized by solid state reaction techniques that require high sintering temperatures (above 1500°C) to eliminate YAM and YAP phases. Though several soft chemical routes have been explored for synthesis of YAG, most of these methods are complex and phase pure materials are not obtained in one step, but prolonged annealing at temperatures around 1000 C or above becomes necessary. One step combustion synthesis of YAG:Ce3+ and related phosphors carried out at 500 C furnace temperature is reported here. Activation with Ce3+ could be achieved during the synthesis without taking recourse to any post-combustion thermal treatment. LEDs prepared from the combustion synthesized YAG:Ce3+, exhibited properties comparable to those produced from the commercial phosphor.

Yadav, Pooja; Gupta, K. Vijay Kumar; Muley, Aarti; Joshi, C. P.; Moharil, S. V.

2011-10-01

31

Combustion synthesis of boride and other composites  

SciTech Connect

This patent describes a self-sustaining combustion synthesis process for producing hard, tough, lightweight B{sub 4}C/TiB{sub 2} composites. It is based on the thermodynamic dependence of adiabatic temperature and product composition on the stoichiometry of the B{sub 4}C and TiB{sub 2} reactants. For lightweight products the composition must be relatively rich in the B{sub 4}C component. B{sub 4}C-rich composites are obtained by varying the initial temperature of the reactants. The product is hard, porous material whose toughness can be enhanced by filling the pores with aluminum or other metal phases using a liquid metal infiltration process. The process can be extended to the formation of other composites having a low exothermic component.0:008360his patent describes a neutron reactivity control system for a LWBR incorporating a stationary seed-blanket core arrangement. The core arrangement includes a plurality of contiguous hexagonal shaped regions. Each region has a central and a peripheral blanket area juxapositioned an annular seed area. The blanket areas contain thoria fuel rods while the annular seed area includes seed fuel rods and movable thoria shim control rods.

Halverson, D.C.; Lum, B.Y.; Munir, Z.A.

1989-11-07

32

Synthesis gas use in internal combustion engines.  

E-print Network

??The objective of this dissertation was to investigate the combustion characteristics of a compression ignition, spark ignition, and homogeneous charge compression ignition engine operating on… (more)

Bika, Anil Singh

2010-01-01

33

Microwave assisted combustion synthesis of non-equilibrium intermetallic compounds.  

PubMed

A simplified model of the microwave-assisted combustion synthesis of Ni and Al metal powders to form the NiAl intermetallic on titanium and steel substrates is presented. The simulation couples an electro-thermal model with a chemical model, accounting for local heat generation due to the highly exothermic nature of the reactions between the powders. Numerical results, validated by experimental values, show that the capability of microwaves to convey energy, and not heat, can be used to alter the temperature profiles during and after the combustion synthesis, leading to unique intermetallic microstructures. This phenomenon is ascribed to the extended existence of high temperature liquid intermetallic phases, which react with the metallic substrates at the interface. Moreover, microwave heating selectivity allows to maintain the bulk of the substrate metallic materials to a much lower temperature, compared to combustion synthesis in conventionally heated furnaces, thus reducing possible unwanted transformations like phase change or oxidation. PMID:21721328

Veronesi, Paolo; Rosa, Roberto; Colombini, Elena; Leonelli, Cristina; Poli, Giorgio; Casagrande, Angelo

2010-01-01

34

Combustion Synthesis of Advanced Porous Materials in Microgravity Environment  

NASA Technical Reports Server (NTRS)

Combustion synthesis, otherwise known as self-propagating high temperature synthesis (SHS), can be used to produce engineered advanced porous material implants which offer the possibility for bone ingrowth as well as a permanent structure framework for the long-term replacement of bone defects. The primary advantage of SHS is based on its rapid kinetics and favorable energetics. The structure and properties of materials produced by SHS are strongly dependent on the combustion reaction conditions. Combustion reaction conditions such as reaction stoichiometry, particle size, green density, the presence and use of diluents or inert reactants, and pre-heating of the reactants, will affect the exothermicity of the reaction. A number of conditions must be satisfied in order to obtain high porosity materials: an optimal amount of liquid, gas and solid phases must be present in the combustion front. Therefore, a balance among these phases at the combustion front must be created by the SHS reaction to successfully engineer a bone replacement material system. Microgravity testing has extended the ability to form porous products. The convective heat transfer mechanisms which operate in normal gravity, 1 g, constrain the combustion synthesis reactions. Gravity also acts to limit the porosity which may be formed as the force of gravity serves to restrict the gas expansion and the liquid movement during reaction. Infiltration of the porous product with other phases can modify both the extent of porosity and the mechanical properties.

Zhang, X.; Moore, J. J.; Schowengerdt, F. D.; Johnson, D. P.

1999-01-01

35

Combustion Synthesis Of Ultralow-density Nanoporous Gold Foams  

SciTech Connect

A new synthetic pathway for producing nanoporous gold monoliths through combustion synthesis from Au bistetrazoJeamine complexes has been demonstrated. Applications of interest for Au nanofoams include new substrates for nanoparticle-mediated catalysis, embedded antennas, and spectroscopy. Integrated support-and-catalystin-one nanocomposites prepared through combustion synthesis of mixed AuBTA/metal oxide pellets would also be an interesting technology approach for low-cost in-line catalytic conversion media. Furthermore, we envision preparation of ultrahigh surface area gold electrodes for application in electrochemical devices through this method.

Tappan, Bruce C [Los Alamos National Laboratory; Mueller, Alex H [Los Alamos National Laboratory; Steiner, Stephen A [Los Alamos National Laboratory; Luther, Erik P [Los Alamos National Laboratory

2008-01-01

36

Combustion synthesis of low exothermic component rich composites  

Microsoft Academic Search

A self-sustaining combustion synthesis process for producing hard, tough, lightweight, low exothermic potential product (LEPP)\\/high exothermic potential product (HEPP) composites is based on the thermodynamic dependence of adiabatic temperature and product composition on the stoichiometry of the LEPP and HEPP reactants. For lightweight products the composition must be relatively rich in the LEPP component. LEPP rich composites are obtained by

Danny C. Halverson; Beverly Y. Lum; Zuhair A. Munir

1991-01-01

37

Combustion synthesis of low exothermic component rich composites  

Microsoft Academic Search

This patent describes a self-sustaining combustion synthesis process for producing hard, tough, lightweight, low exothermic potential product (LEPP)\\/high exothermic potential product (HEPP) composites based on the thermodynamic dependence of adiabatic temperature and product composition on the stoichiometry of the LEPP and HEPP reactants. For lightweight products the composition must be relatively rich in the LEPP component. LEPP rich composites are

D. C. Halverson; B. Y. Lum; Z. A. Munir

1991-01-01

38

Combustion synthesis of ceramic and metal-matrix composites  

NASA Technical Reports Server (NTRS)

Combustion synthesis or self-propagating high temperature synthesis (SHS) is effected by heating a reactant mixture, to above the ignition temperature (Tig) whereupon an exothermic reaction is initiated which produces a maximum or combustion temperature, Tc. These SHS reactions are being used to produce ceramics, intermetallics, and composite materials. One of the major limitations of this process is that relatively high levels of porosity, e.g., 50 percent, remain in the product. Conducting these SHS reactions under adiabatic conditions, the maximum temperature is the adiabatic temperature, Tad, and delta H (Tad) = 0, Tad = Tc. If the reactants or products go through a phase change, the latent heat of transformation needs to be taken into account.

Moore, John J.; Feng, Heng J.; Hunter, Kevin J.; Wirth, David G.

1993-01-01

39

Gas-Phase Combustion Synthesis of Nonoxide Nanoparticles in Microgravity  

NASA Technical Reports Server (NTRS)

Gas-phase combustion synthesis is a promising process for creating nanoparticles for the growing nanostructure materials industry. The challenges that must be addressed are controlling particle size, preventing hard agglomerates, maintaining purity, and, if nonoxides are synthesized, protecting the particles from oxidation and/or hydrolysis during post-processing. Sodium-halide Flame Encapsulation (SFE) is a unique methodology for producing nonoxide nanoparticles that addresses these challenges. This flame synthesis process incorporates sodium and metal-halide chemistry, resulting in nanoparticles that are encapsulated in salt during the early stages of their growth in the flame. Salt encapsulation has been shown to allow control of particle size and morphology, while serving as an effective protective coating for preserving the purity of the core particles. Metals and compounds that have been produced using this technology include Al, W, Ti, TiB2, AlN, and composites of W-Ti and Al-AlN. Oxygen content in SFE synthesized nano- AlN has been measured by neutron activation analysis to be as low as 0.54wt.%, as compared to over 5wt.% for unprotected AlN of comparable size. The overall objective of this work is to study the SFE process and nano-encapsulation so that they can be used to produce novel and superior materials. SFE experiments in microgravity allow the study of flame and particle dynamics without the influence of buoyancy forces. Spherical sodium-halide flames are produced in microgravity by ejecting the halide from a spherical porous burner into a quiescent atmosphere of sodium vapor and argon. Experiments are performed in the 2.2 sec Drop Tower at the NASA-Glenn Research Center. Numerical models of the flame and particle dynamics were developed and are compared with the experimental results.

Axelbaum, R. L.; Kumfer, B. M.; Sun, Z.; Chao, B. H.

2001-01-01

40

Cermet materials prepared by combustion synthesis and metal infiltration  

DOEpatents

Ceramic-metal composites (cermets) are made by a combination of self-propagating high temperature combustion synthesis and molten metal infiltration. Solid-gas, solid-solid and solid-liquid reactions of a powder compact produce a porous ceramic body which is infiltrated by molten metal to produce a composite body of higher density. AlN-Al and many other materials can be produced. 6 figures.

Holt, J.B.; Dunmead, S.D.; Halverson, D.C.; Landingham, R.L.

1991-01-29

41

Glycine-nitrate combustion synthesis of finely dispersed alumina  

Microsoft Academic Search

The possibility of synthesizing different crystalline modifications of alumina Al2O3 by combustion reactions of a mixture of aluminum nitrate with glycine has been analyzed. Aggregated powders of ?-Al2O3 that do not transform into the corundum structure after annealing at a temperature of 1000°C have been prepared. The influence\\u000a of the synthesis conditions on the specific surface area, bulk density, porosity,

V. D. Zhuravlev; V. G. Vasil’ev; E. V. Vladimirova; V. G. Shevchenko; I. G. Grigorov; V. G. Bamburov; A. R. Beketov; M. V. Baranov

2010-01-01

42

Combustion synthesis of silicon carbide assisted by a magnesium plus polytetrafluoroethylene mixture  

SciTech Connect

In this study, the use of SiC combustion synthesis for immobilization of {sup 14}C was considered. Due to the low exothermicity of the reaction between silicon and graphite, a highly exothermic mixture (magnesium and polytetrafluoroethylene) was used both as a chemical oven and activate additive in the mixture. With this configuration the reaction between graphite and silicon was initiated and propagated on the whole sample. The self-propagating high temperature synthesis samples were characterized by using scanning electron microscopy and X-ray diffraction.

Ayral, R.M. [Institut Charles Gerhardt Montpellier, PMOF-UM2-CNRS Pl. E. Bataillon, 34095 Montpellier Cedex 5 (France); Rouessac, F., E-mail: florence.rouessac@univ-montp2.fr [Institut Charles Gerhardt Montpellier, PMOF-UM2-CNRS Pl. E. Bataillon, 34095 Montpellier Cedex 5 (France); Massoni, N. [CEA, DEN, DTCD, 30207 Bagnols-sur-Ceze (France)

2009-11-15

43

Synthesis and investigations on CO catalytic oxidation activity of nanostructured Ce0.5Zr0.5O2 prepared by combustion method using polyvinyl alcohol  

NASA Astrophysics Data System (ADS)

Nanostructured Ce0.5Zr0.5O2 samples were synthesized by the combustion of the gel obtained from a mixture of polyvinyl alcohol (PVA) and metal nitrates at a temperature as low as 600?°C. The prepared samples were investigated by x-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). Their specific surface areas were determined from N2 adsorption measurement at 77?K by Brunauer–Emmet–Teller (BET) method and their CO catalytic oxidation activities were investigated using a Landcom II instrument. The XRD and FE-SEM results revealed that Ce0.5Zr0.5O2 nanocrystallines began to grow isotropically at 600?°C with the nanostructure found in all prepared samples. Further thermal treatment at 600?°C for 2?h yields the single crystalline phase Ce0.5Zr0.5O2 nanostructured samples with average crystalline size < 50?nm and specific surface area of about 73?m2?g?1. Besides, the effects of a number of factors such as calcination temperature and Ce/Zr molar ratio on the formation of prepared samples as well as the oxidative conversion of carbon monoxide over nanostructured Ce0.5Zr0.5O2 catalyst were also studied.

Nhiem Dao, Ngoc; Luu, Minh Dai

2012-03-01

44

Combustion Synthesis of Doped Thermoelectric Oxides  

SciTech Connect

Self-propagating high-temperature synthesis (SHS) was used to prepare silver doped calcium cobaltates (Ca1.24- xAgxCo1.62O3.86, x = 0.03 - 0.12) powders. SHS is a simple and economic process to synthesize ceramic materials with minimum energy requirements. The heat generated by the SHS reaction can sustain the propagation of the reaction front and convert reactants to desired products. The effect of doping level on thermoelectric properties was investigated in this study. Results show the substitution of calcium by silver decreases the thermal conductivity significantly. XRD and surface area measurements show synthesized powders are phase pure and have large specific surface areas.

Selig, Jiri [Lamar University; Lin, Sidney [Lamar University; Lin, Hua-Tay [ORNL; Johnson, D Ray [ORNL

2012-01-01

45

Synthesis and characterization of iron orthophosphate by solution combustion method  

SciTech Connect

Graphical abstract: Display Omitted Highlights: ? Solution combustion synthesis was firstly employed to prepare FePO{sub 4}. ? Pure, well-crystallized and porous FePO{sub 4} was obtained and characterized. ? The results proved SCS a time saving and practically applicable method. -- Abstract: The present work applies solution combustion synthesis (SCS) by employing glycine as organic fuel to stimulate the synthesis of pure iron orthophosphate with well-defined reaction parameters. The structural and morphological properties of the products were characterized and confirmed by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and surface analyzer, respectively. Thermal behaviors were also investigated by TG/DT analyses. The optimal condition was set at 500 °C in a few minutes, giving pure iron orthophosphate with a good level of crystallinity and 11,769 m{sup 2}/g surface area. The results proved SCS a time saving and practically applicable method.

Baykan, Demet [Department of Chemistry, Faculty of Science, Hacettepe University, Ankara (Turkey)] [Department of Chemistry, Faculty of Science, Hacettepe University, Ankara (Turkey); Oztas, Nursen Altuntas, E-mail: nursen@hacettepe.edu.tr [Department of Chemistry, Faculty of Science, Hacettepe University, Ankara (Turkey)

2012-12-15

46

Formation of nanostructured fluorapatite via microwave assisted solution combustion synthesis.  

PubMed

Fluorapatite (FA) has potential applications in dentistry and orthopedics, but its synthesis procedures are time consuming. The goal of the present study is to develop a quick microwave assisted solution combustion synthesis method (MASCS) for the production of FA particles. With this new processing, FA particles were successfully synthesized in minutes. Additionally, unique structures including nanotubes, hexagonal crystals, nanowhiskers, and plate agglomerates were prepared by controlling the solution composition and reaction time. In particular, the as-synthesized FA nanotubes presented a "Y" shape inner channel along the crystal axis. It is supposed that the channel formation is caused by the crystal growth and removal of water soluble salts during processing. The as-synthesized FA nanotubes showed good cytocompatibility, the cells cultured with a higher FA concentration demonstrated greater growth rate. With this new and easily applied MASCS processing application, FA nanoparticles have increased potential in dental and orthopedic applications. PMID:24582261

Nabiyouni, Maryam; Zhou, Huan; Luchini, Timothy J F; Bhaduri, Sarit B

2014-04-01

47

A density functional theory study of hydrocarbon combustion and synthesis on Ni surfaces.  

PubMed

Combustion and synthesis of hydrocarbons may occur directly (CH ? C + H and CO ? C + O) or via a formyl (CHO) intermediate. Density functional theory (DFT) calculations were performed to calculate the activation and reaction energies of these reactions on Ni(111), Ni(110), and Ni(100) surfaces. The results show that the energies are sensitive to the surface structure. The dissociation barrier for methylidyne (CH ? C + H: catalytic hydrocarbon combustion) is lower than that for its oxidation reaction (CH + O ? CHO) on the Ni(110) and Ni(100) surfaces. However the oxidation barrier is lower than that for dissociation on the Ni(111) surface. The dissociation barrier for methylidyne dissociation decreases in the order Ni(111) > Ni(100) > Ni(110). The barrier of formyl dissociation to CO and H is almost the same on the Ni(111) and Ni(110) surfaces and is lower compared to the Ni(100) surface. The energy barrier for carbon monoxide dissociation (CO ? C + O: catalytic hydrocarbon synthesis) is higher than that of for its hydrogenation reaction (CO + H ? CHO) on all three surfaces. This means that the hydrogenation to CHO is favored on these nickel surfaces. The energy barrier for both reactions decreases in the order Ni(111) > Ni(100) > Ni(110). The barrier for formyl dissociation to CH + O decreases in the order Ni(100) > Ni(111) > Ni(110). Based on these DFT calculations, the Ni(110) surface shows a better catalytic activity for hydrocarbon combustion compared to the other surfaces, and Ni is a better catalyst for the combustion reaction than for hydrocarbon synthesis, where the reaction rate constants are small. The reactions studied here support the BEP principles with R(2) values equal to 0.85 for C-H bond breaking/forming and 0.72 for C-O bond breaking /forming reactions. PMID:25690364

Mohsenzadeh, Abas; Richards, Tobias; Bolton, Kim

2015-03-01

48

Characteristics of fluid flow in the combustion synthesis of TiC from the elements  

NASA Technical Reports Server (NTRS)

The results of a numerical investigation of finite reservoir effects on capillary spreading at small reservoir dimensions are presently related to wave propagation phenomena in the combustion synthesis of TiC from its two elemental constituents. It is noted that gravitational forces can affect bubble coalescence by nonbuoyant means under the suitable conditions, although these conditions are expected to be rare in combustion synthesis. Finite-curved reservoirs can drive capillary flow due to surface tension and wall contact forces; these cause the wall and the metal to be completely reconfigured during combustion synthesis.

Valone, S. M.; Behrens, R. G.

1987-01-01

49

Combustion synthesis of low exothermic component rich composites  

SciTech Connect

This patent describes a self-sustaining combustion synthesis process for producing hard, tough, lightweight, low exothermic potential product (LEPP)/high exothermic potential product (HEPP) composites based on the thermodynamic dependence of adiabatic temperature and product composition on the stoichiometry of the LEPP and HEPP reactants. For lightweight products the composition must be relatively rich in the LEPP component. LEPP rich composites are obtained by varying the initial temperature of the reactants. The product is hard, porous material whose toughness can be enhanced by filling the pores with aluminum or other metal phases using a liquid metal infiltration process. The process can be extended to the formation of other composites having a low exothermic component.

Halverson, D.C.; Lum, B.Y.; Munir, Z.A.

1991-02-05

50

Combustion synthesis of low exothermic component rich composites  

DOEpatents

A self-sustaining combustion synthesis process for producing hard, tough, lightweight, low exothermic potential product (LEPP)/high exothermic potential product (HEPP) composites is based on the thermodynamic dependence of adiabatic temperature and product composition on the stoichiometry of the LEPP and HEPP reactants. For lightweight products the composition must be relatively rich in the LEPP component. LEPP rich composites are obtained by varying the initial temperature of the reactants. The product is hard, porous material whose toughness can be enhanced by filling the pores with aluminum or other metal phases using a liquid metal infiltration process. The process can be extended to the formation of other composites having a low exothermic component.

Halverson, Danny C. (Modesto, CA); Lum, Beverly Y. (Livermore, CA); Munir, Zuhair A. (Davis, CA)

1991-01-01

51

Combustion diagnostic for active engine feedback control  

DOEpatents

This invention detects the crank angle location where combustion switches from premixed to diffusion, referred to as the transition index, and uses that location to define integration limits that measure the portions of heat released during the combustion process that occur during the premixed and diffusion phases. Those integrated premixed and diffusion values are used to develop a metric referred to as the combustion index. The combustion index is defined as the integrated diffusion contribution divided by the integrated premixed contribution. As the EGR rate is increased enough to enter the low temperature combustion regime, PM emissions decrease because more of the combustion process is occurring over the premixed portion of the heat release rate profile and the diffusion portion has been significantly reduced. This information is used to detect when the engine is or is not operating in a low temperature combustion mode and provides that feedback to an engine control algorithm.

Green, Jr., Johney Boyd (Knoxville, TN); Daw, Charles Stuart (Knoxville, TN); Wagner, Robert Milton (Knoxville, TN)

2007-10-02

52

Combustion  

NSDL National Science Digital Library

In this chemistry activity, learners discover that the weight of the product of combustion is greater than that of the starting material. Learners will compare the weight of steel wool before and after it is heated. Learners are asked to consider why the steel wool weighs more (oxidation) as well as write the balanced chemical equation for the burning of steel. This activity uses an open flame; adult supervision is recommended. The resource includes notes for educators and extension ideas.

2014-01-28

53

Design and Operation of the Synthesis Gas Generator System for Reformed Propane and Glycerin Combustion  

NASA Astrophysics Data System (ADS)

Due to an increased interest in sustainable energy, biodiesel has become much more widely used in the last several years. Glycerin, one major waste component in biodiesel production, can be converted into a hydrogen rich synthesis gas to be used in an engine generator to recover energy from the biodiesel production process. This thesis contains information detailing the production, testing, and analysis of a unique synthesis generator rig at the University of Kansas. Chapter 2 gives a complete background of all major components, as well as how they are operated. In addition to component descriptions, methods for operating the system on pure propane, reformed propane, reformed glycerin along with the methodology of data acquisition is described. This chapter will serve as a complete operating manual for future students to continue research on the project. Chapter 3 details the literature review that was completed to better understand fuel reforming of propane and glycerin. This chapter also describes the numerical model produced to estimate the species produced during reformation activities. The model was applied to propane reformation in a proof of concept and calibration test before moving to glycerin reformation and its subsequent combustion. Chapter 4 first describes the efforts to apply the numerical model to glycerin using the calibration tools from propane reformation. It then discusses catalytic material preparation and glycerin reformation tests. Gas chromatography analysis of the reformer effluent was completed to compare to theoretical values from the numerical model. Finally, combustion of reformed glycerin was completed for power generation. Tests were completed to compare emissions from syngas combustion and propane combustion.

Pickett, Derek Kyle

54

Combustion synthesis of hexagonal aluminum nitride powders under low nitrogen pressure  

Microsoft Academic Search

The synthesis of aluminum nitride (AlN) powders was carried out by combustion of aluminum (Al) powder under low nitrogen pressure (?0.5 MPa) with carbon black (CB) as the dispersion agent to prevent the coalescence of the aluminum. The combustion was successful when the weight ratio between CB and Al, CB\\/Al, ranged from 0.02 to 1.5, while the combustion failed at

R.-C. Juang; C.-J. Lee; C.-C. Chen

2003-01-01

55

An overview of European activities on microgravity combustion  

NASA Technical Reports Server (NTRS)

The global objective of the European efforts in microgravity combustion is to combine theoretical and experimental work, both under normal and reduced gravity, to progress in the basic understanding of gravity dependent phenomena in various combustion situations. The first phase of the European activities on microgravity combustion has been summarized in refs. 1, 2, and 3. This overview will summarize the more recent developments. The focus will be on new experimental facilities, new research topics, and new collaborative efforts.

Goekalp, Iskender

1993-01-01

56

Kinetics of combustion synthesis in the TiC and TiC-Ni systems  

Microsoft Academic Search

The self-propagating reactions, termed self-propagating high-temperature synthesis (SHS), or more simply, combustion synthesis, have received increasing attention especially for the preparation of refractory ceramic and intermetallic compounds. The kinetics and mechanisms of combustion reactions in the Ti-C and Ti-C-Ni systems were studied. Samples were produced by igniting compacts of elemental Ti, C, and Ni powders with a tungsten heating coil

Stephen D. Dunmead; J. B. Holt; D. W. Readey; C. E. Semier

1989-01-01

57

Characteristics of the combustion synthesis of TiC and Fe-TiC composites  

Microsoft Academic Search

The combustion synthesis of TiC, using the thermal explosion mode, was investigated by varying some of the process parameters including the reactant particle size, the pre-compaction pressure, and the heating rate. Based on these observations, a combustion model for the reaction was developed. When iron was added to titanium and carbon black powders, the ignition temperature was dictated by the

A. Saidi; A. Chrysanthou; J. V. Wood; J. L. F. Kellie

1994-01-01

58

Combustion synthesis and nanomaterials Singanahally T. Aruna a,*, Alexander S. Mukasyan b,1  

E-print Network

b Department of Chemical and Biomolecular Engineering, Center for Molecularly Engineered Materials on the mechanisms of internal electromagnetic fields generation during combustion in heterogeneous systems, as well]. The specifics of solu- tion combustion (SC) method for the synthesis of lamp phosphor materials has also been

Mukasyan, Alexander

59

Processing and characterization of functionally graded titanium/titanium boride/titanium diboride composites by combustion synthesis/compaction and microwaves  

NASA Astrophysics Data System (ADS)

The use of functionally graded materials (FGMs) in aircraft, armor, medical and electronics industries is becoming more common as their performances exceed the capabilities of homogeneous materials. The concept of functionally graded materials (FGMs) was initially proposed to minimize problems such as poor mechanical integrity and interfacial adhesion associated with the presence of abrupt interfaces in metal-ceramic bonded structures. In this thesis, the combustion synthesis (CS) method was explored in fabricating FGMs in the Ti-B binary system. Among other methods CS has shown potential in terms of process economics and simplicity. Compositionally graded trilayered and five layered composites were produced by using three combustion methods: conventional combustion synthesis, combustion synthesis/compaction and microwave activated combustion synthesis. The porosity formation during CS has precluded the widespread use of this method. Therefore, a strategy was proposed to reduce the porosity, first, through control of vigorous combustion reactions and second, by applying pressure on the ignited samples. The control of the reactions was done by selecting compositions away from the stoichiometry without resorting to adding a third element into the system. These initiatives resulted in net shaped graded composites with improved density and hardness. As another processing method, microwave activated combustion synthesis was utilized by using SiC as a susceptor. When compared to conventional CS, microwave processed FGMs exhibited better microstructural homogeneity. All three methods resulted in Ti-TiB-TiB2 graded composite materials with continuous and crack free interfaces. Moire Interferometry tests were conducted to compare the deformation behavior of conventional combustion synthesized FGMs with that of microwave activated FGMs. The comparison was based on their in-plane displacements under compression loading. It was found that microwave produced FGMs exhibit a more compliant behavior. Under loads as low as 0.37 kN, the composites strained plastically. Also higher boron content layers exhibited a more compliant behavior compared to pure titanium layers.

Cirakoglu, Menderes

60

Combustion synthesis of ZnS in microgravity  

SciTech Connect

The self-heating nature of SHS (Self-propagating High-temperature Synthesis) makes it particularly suitable for microgravity processing of materials where weight and power requirements are severely restricted. The absence of convection, hydrostatic pressure, and phase separation permits the combustion front dynamics and solidification processes of SHS to be studied under controlled conditions. This paper describes recent ground-based and microgravity (NASA KC-135 parabolic flight) experiments on SHS processing of ZnS. A novel technique was used for preparing the precursor mixture of Zn + S by mixing the zinc with molten sulfur, which allows the synthesis of a high-density and high-purity product. The flame speed, quenching diameter, and temperature profile in the flame front and crystal structure of the synthesized samples have been determined. Thermocouple measurement of the temperature profile in the flame front indicates that the thermal thickness of the flame is less than 0.3 mm. The average flame speed is of the order of 7 mm/s, and slightly lower values ({approximately}4 mm/s) are observed near the quenching limit. It was found that the flame speed is not stable along the samples with diameters more than 12 mm. The quenching diameter is found to be of the order of 5 mm (in microgravity less than 4 mm). X-ray diffraction data show a wurtzite structure both in ground-based and in-flight synthesized samples, and the lattice`s parameters are most similar to the ideal ZnS wurtzite structure in the outer part of samples synthesized in microgravity. The ability to provide containerless SHS processing of molten ZnS in microgravity also has been demonstrated.

Goroshin, S.; Lee, J.H.S.; Frost, D.L. [McGill Univ., Montreal, Quebec (Canada). Dept. of Mechanical Engineering

1994-12-31

61

Technology Awareness Workshop on Active Combustion Control (ACC) in Propulsion Systems: JANNAF Combustion Subcommittee Workshop  

NASA Technical Reports Server (NTRS)

A JANNAF Combustion Subcommittee Technology Awareness Seminar on Active Combustion Control (ACC) in Propulsion Systems' was held 12 November 1997 at the NASA Lewis Research Center (LeRC), Cleveland, Ohio. The objectives of the seminar were: 1) Define the need and potential of ACC to meet future requirements for gas turbines and ramjets; 2) Explain general principles of ACC and discuss recent successes to suppress combustion instabilities, increase combustion efficiency, reduce emission, and extend flammability limits; 3) Identify R&D barriers/needs for practical implementation of ACC; 4) Explore potential for improving coordination of future R&D activities funded by various government agencies. Over 40 individuals representing senior management from over 20 industry and government organizations participated. This document summarizes the presentations and findings of this seminar.

Fry, Ronald S. (Editor); Gannaway, Mary T. (Editor)

1997-01-01

62

Separation and Purification Technology 25 (2001) 117126 Perovskite membranes by aqueous combustion synthesis  

E-print Network

these materials, Lanthanum chromite (LC) perovskite shows high electronic conductiv- ity, and stability under bothSeparation and Purification Technology 25 (2001) 117­126 Perovskite membranes by aqueous combustion synthesis: synthesis and properties Alexander S. Mukasyan, Colleen Costello, Katherine P. Sherlock, David

Mukasyan, Alexander

63

Active combustion control : modeling, design and implementation  

E-print Network

Continuous combustion systems common in propulsion and power generation applications are susceptible to thermoacoustic instability, which occurs under lean burn conditions close to the flammability where most emissions and ...

Park, Sungbae, 1973-

2004-01-01

64

An investigation of the ignition manner effects on combustion synthesis  

Microsoft Academic Search

The multi-point ignition of combustion synthesizing NiAl compound created by computational means has been analyzed in this article. Since the combustion reaction of Ni and Al is a low exothermic reaction, it has been found that the combustion front hardly propagates in order to complete the reaction. In this study, the reaction is subsequently ignited at different points or it

Hung-Pin Li

2003-01-01

65

SLUDGE COMBUSTOR USING SWIRL AND ACTIVE COMBUSTION CONTROL  

EPA Science Inventory

A research program directed at developing technology for compact shipboard incinerators for sludges is described. The concept utilizes previously developed Vortex Containment Combustor (VCC) as a primary unit with an active combustion control afterburner (AB). The overall power s...

66

Using Combustion Synthesis to Reinforce Berms and Other Regolith Structures  

NASA Technical Reports Server (NTRS)

The Moonraker Excavator and other tools under development for use on the Moon, Mars, and asteroids will be employed to construct a number of civil engineering projects and to mine the soil. Mounds of loose soil will be subject to the local transport mechanisms plus artificial mechanisms such as blast effects from landers and erosion from surface vehicles. Some of these structures will require some permanence, with a minimum of maintenance and upkeep. Combustion Synthesis (CS) is a family of processes and techniques whereby chemistry is used to transform materials, often creating flame in a hard vacuum. CS can be used to stabilize civil engineering works such as berms, habitat shielding, ramps, pads, roadways, and the like. The method is to unroll thin sheets of CS fabric between layers of regolith and then fire the fabric, creating a continuous sheet of crusty material to be interposed among layers of loose regolith. The combination of low-energy processes, ISRU (in situ resource utilization) excavator, and CS fabrics, seems compelling as a general method for establishing structures of some permanence and utility, especially in the role of robotic missions as precursors to manned exploration and settlement. In robotic precursory missions, excavator/ mobility ensembles mine the Lunar surface, erect constructions of soil, and dispense sheets of CS fabrics that are covered with layers of soil, fired, and then again covered with layers of soil, iterating until the desired dimensions and forms are achieved. At the base of each berm, for example, is a shallow trench lined with CS fabric, fired and filled, mounded, and then covered and fired, iteratively to provide a footing against lateral shear. A larger trench is host to a habitat module, backfilled, covered with fabric, covered with soil, and fired. Covering the applied CS fabric with layers of soil before firing allows the resulting matrix to incorporate soil both above and below the fabric ply into the fused layer, developing a very irregular surface which, like sandpaper, can provide an anchor for loose soil. CS fabrics employ a coarse fiberglass weave that persists as reinforcement for the fired material. The fiberglass softens at a temperature that exceeds the combustion temperature by factors of two to three, and withstands the installation process. This type of structure should be more resistant to rocket blast effects from Lunar landers.

Rodriquez, Gary

2013-01-01

67

Combustion synthesis of LiGa and LiAl intermetallic alloys  

NASA Astrophysics Data System (ADS)

LiAl and LiGa intermetallic alloys have been synthesized using the simultaneous combustion mode of combustion synthesis. LiAl intermetallic is potentially suitable as a temper alloy for producing aluminum-lithium alloys and as an anodic material for high-energy batteries. LiGa can be used as a reduction alloy to recover valuable reactive metals from molten salt effluent in actinide recovery technology. The effects of particle size, preignition heating rate, and theoretical green density on the ignition and combustion temperatures have been studied in an effort to more precisely control the synthesis reaction of these intermetallics. A lithium particle size of -20 /xm was found to be suitable when the combustion synthesis reaction was conducted at a high heating rate (>1.0 cC/s) and a moderate green density (55 to 65 pct theoretical). Preignition diffusion is suggested as the cause for low exothermic heat release at high green densities. A combustion temperature above the melting point of the LiGa intermetallic compound can be achieved under optimized conditions. However, the exothermicity and, therefore, the adiabatic temperature is too low for either LiAl or LiGa to be produced by the propagating mode of combustion synthesis.

Pritchett, S. R.; Mishra, B.; Moore, J. J.

1995-02-01

68

Gas-Phase Combustion Synthesis of Aluminum Nitride Powder  

NASA Technical Reports Server (NTRS)

Due to its combined properties of high electrical resistivity and high thermal conductivity aluminum nitride (AlN) is a highly desirable material for electronics applications. Methods are being sought for synthesis of unagglomerated, nanometer-sized powders of this material, prepared in such a way that they can be consolidated into solid compacts having minimal oxygen content. A procedure for synthesizing these powders through gas-phase combustion is described. This novel approach involves reacting AlCl3, NH3, and Na vapors. Equilibrium thermodynamic calculations show that 100% yields can be obtained for these reactants with the products being AlN, NaCl, and H2. The NaCl by-product is used to coat the AlN particles in situ. The coating allows for control of AlN agglomeration and protects the powders from hydrolysis during post-flame handling. On the basis of thermodynamic and kinetic considerations, two different approaches were employed to produce the powder, in co-flow diffusion flame configurations. In the first approach, the three reactants were supplied in separate streams. In the second, the AlCl3 and NH3 were premixed with HCl and then reacted with Na vapor. X-ray diffraction (XRD) spectra of as-produced powders show only NaCl for the first case and NaCl and AlN for the second. After annealing at 775 C tinder dynamic vacuum, the salt was removed and XRD spectra of powders from both approaches show only AlN. Aluminum metal was also produced in the co-flow flame by reacting AlCl3 with Na. XRD spectra of as-produced powders show the products to be only NaCl and elemental aluminum.

Axelbaum, R. L.; Lottes, C. R.; Huertas, J. I.; Rosen, L. J.

1996-01-01

69

Synthesis of Nano-scaled -Al2O3 Particles by Combustion Spray Byungsei Jun1,a  

E-print Network

Synthesis of Nano-scaled -Al2O3 Particles by Combustion Spray Pyrolysis Byungsei Jun1,a Sangjin Lee@ems.psu.edu Keywords: combustion, spray pyrolysis, -Al2O3, nano, particles Abstract. Unagglomerated -Al2O3 powders concentration [7]. Here we describe a modified combustion spray pyrolysis method for synthesizing ultrafine -Al2

Messing, Gary L.

70

Synthesis of fine-grained .alpha.-silicon nitride by a combustion process  

DOEpatents

A combustion synthesis process for the preparation of .alpha.-silicon nitride and composites thereof is disclosed. Preparation of the .alpha.-silicon nitride comprises the steps of dry mixing silicon powder with an alkali metal azide, such as sodium azide, cold-pressing the mixture into any desired shape, or loading the mixture into a fused, quartz crucible, loading the crucible into a combustion chamber, pressurizing the chamber with nitrogen and igniting the mixture using an igniter pellet. The method for the preparation of the composites comprises dry mixing silicon powder (Si) or SiO.sub.2, with a metal or metal oxide, adding a small amount of an alkali metal azide such as sodium azide, introducing the mixture into a suitable combustion chamber, pressurizing the combustion chamber with nitrogen, igniting the mixture within the combustion chamber, and isolating the .alpha.-silicon nitride formed as a reaction product.

Holt, J. Birch (San Jose, CA); Kingman, Donald D. (Danville, CA); Bianchini, Gregory M. (Livermore, CA)

1990-01-01

71

Solid-state combustion synthesis of ceramics and alloys in reduced gravity  

NASA Technical Reports Server (NTRS)

Possible microgravity effects are explored in the combustion synthesis of ceramics and alloys from their constituent elements. Molten intermediates are typically present during the combustion process, thereby offering the chance for natural convection to take place. Numerical simulations suggest that the combustion front in concert with gravity may act as a partial zone-refinement mechanism which is attempting to sweep out porosity in the sample. Contrary to suggestions by dimensional analysis, no effects on the combustion rate are seen. An analytical model of the combustion velocity as a function of the gravitational field and the spreading rate of molten material gives the correct order of magnitude of the gravity effect as measured by centrifuge experiments.

Valone, S. M.; Behrens, R. G.

1988-01-01

72

Lean Premixed Combustion/Active Control  

SciTech Connect

An experimental comparison between two contrasting fuel-air swirlers for industrial gas turbine applications was undertaken at the United Technologies Research Center. The first, termed an Aerodynamic nozzle, relied on the prevailing aerodynamic forces to stabilize the downstream combustion zone. The second configuration relied on a conventional bluff plate for combustion stability and was hence named a Bluff-Body nozzle. Performance mapping over the power curve revealed the acoustic superiority of the Bluff-Body nozzle. Two dimensional Rayleigh indices calculated from CCD images identified larger acoustic driving zones associated with the Aerodynamic nozzle relative to its bluff counterpart. The Bluff-Body's success is due to increased flame stabilization (superior anchoring ability) which reduced flame motion and thermal/acoustic coupling.

D. J. Seery

2000-02-01

73

Simultaneous combustion synthesis (thermal explosion mode) and extrusion of nickel aluminides  

Microsoft Academic Search

Combustion synthesis (CS) is a low-energy processing approach for a wide range of materials (e.g. ceramics, intermetallics and composites), whereby reactants are ignited to spontaneously transform to products in an exothermic reaction. The process can be subdivided into two modes of ignition. The first is termed self-propagating high temperature synthesis (SHS) in which a reactant compact is typically ignited at

K. Morsi; S. O. Moussa; James J. Wall

2005-01-01

74

Low-reactive circulating fluidized bed combustion (CFBC) fly ashes as source material for geopolymer synthesis  

Microsoft Academic Search

In this contribution, low-reactive circulating fluidized bed combustion (CFBC) fly ashes (CFAs) have firstly been utilized as a source material for geopolymer synthesis. An alkali fusion process was employed to promote the dissolution of Si and Al species from the CFAs, and thus to enhance the reactivity of the ashes. A high-reactive metakaolin (MK) was also used to consume the

Hui Xu; Qin Li; Lifeng Shen; Mengqun Zhang; Jianping Zhai

2010-01-01

75

DEXTROSE-TEMPLATED MICROWAVE-ASSISTED COMBUSTION SYNTHESIS OF SPONGY METAL OXIDES  

EPA Science Inventory

Microwave-assisted combustion synthesis of porous nanocrystalline titania and carbon coated titania is reported using dextrose as template and the product was compared with the one obtained using conventional heating furnace. Out of three compositions viz., 1:1, 1:3, and 1:5 (met...

76

Synthesis of Diopside by Solution Combustion Process Using Glycine Fuel  

NASA Astrophysics Data System (ADS)

Nano ceramic Diopside (CaMgSi2O6) powders are synthesized by Solution Combustion Process(SCS) using Calcium nitrate, Magnesium nitrate as oxidizer and glycine as fuel, fumed silica as silica source. Ammonium nitrate (AN) is used as extra oxidizer. Effect of AN on Diopside phase formation is investigated. The adiabatic flame temperatures are calculated theoretically for varying amount of AN according to thermodynamic concept and correlated with the observed flame temperatures. A “Multi channel thermocouple setup connected to computer interfaced Keithley multi voltmeter 2700” is used to monitor the thermal events during the process. An interpretation based on maximum combustion temperature and the amount of gases produced during reaction for various AN compositions has been proposed for the nature of combustion and its correlation with the characteristics of as synthesized powder. These powders are characterized by XRD, SEM showing that the powders are composed of polycrystalline oxides with crystallite size of 58nm to 74nm.

Sherikar, Baburao N.; Umarji, A. M.

77

40 CFR 60.1855 - What records must I keep for municipal waste combustion units that use activated carbon?  

Code of Federal Regulations, 2014 CFR

...waste combustion units that use activated carbon? 60.1855 Section 60.1855 Protection...waste combustion units that use activated carbon? For municipal waste combustion units that use activated carbon to control dioxins/furans or...

2014-07-01

78

40 CFR 60.1370 - What records must I keep for municipal waste combustion units that use activated carbon?  

Code of Federal Regulations, 2014 CFR

...waste combustion units that use activated carbon? 60.1370 Section 60.1370 Protection...waste combustion units that use activated carbon? For municipal waste combustion units that use activated carbon to control dioxins/furans or...

2014-07-01

79

Synthesis and characterization of actinide metal compounds formed by combustion  

SciTech Connect

This paper briefly describes the results of attempts to synthesize arsenides, phosphides, and antimonides of uranium and thorium using Self-Propagating High-Temperature Synthesis (SHS) techniques. This paper first summarizes the chemistry and thermodynamics of these chemical systems, describes SHS synthesis techniques, and then describes the results of the syntheses using data from powder x-ray diffraction, metallographic, and electron microprobe analyses.

Behrens, R.G.; King, M.A.

1985-01-01

80

Solution combustion synthesis and optimization of phosphors for plasma display panels  

NASA Astrophysics Data System (ADS)

The optimization of primary phosphors required for display panels were carried out. Phosphors were synthesized by simple solution combustion technique. The synthesis is based on the exothermic reaction between the fuel (urea) and oxidizer (ammonium nitrate).The heat generated in the reaction is used for auto combustion of precursors. The crystal structures of the prepared samples were confirmed by powder XRD technique and particle morphology by FE-SEM. The Photoluminescence properties were investigated under ultraviolet (UV) and vacuum ultraviolet (VUV) radiations respectively. Prepared phosphors were found to have the best luminous performance with respect to intensity and color purity under 254 nm and 147 nm wavelength radiations.

Ingle, J. T.; Sonekar, R. P.; Omanwar, S. K.; Wang, Yuhua; Zhao, Lei

2014-06-01

81

Combustion synthesis of TiB2-Al2O3-Al composite materials  

NASA Technical Reports Server (NTRS)

The oxide-aluminum exothermic reduction reaction is presently used in the combustion-synthesis of ceramic/metal composites. An excess of Al is used in the reacting materials, which rapidly generate enough heat to exceed Al's melting point. The molten Al thus evolved is allowed to infiltrate the porous ceramic matrix as the exothermic reaction proceeds; this feature of the process turns the disadvantage of high porosity levels in combustion-synthesized materials into an advantage. Attention is given to the system obtained with 3TiO2 + 3B2O3 + (10-x)Al starting materials.

Feng, H. J.; Moore, J. J.; Wirth, D. G.

1991-01-01

82

Combustion Synthesis of BaCaP207:Eu2+ Pyrophosphate Blue Phosphor For Solid State Lighting  

NASA Astrophysics Data System (ADS)

In this paper, synthesis of Eu2+ activated BaCaP207 pyrophosphate based phosphor by using modified combustion synthesis has been reported and studied for its X-ray diffraction pattern (XRD).Photoluminescence (PL) properties under near ultraviolet (n-UV) excitation . The BaCaP207:Eu2+ exhibits unique color: a blue band centered at 455 nm originating from Eu2+ when excited at 354 nm, which is suitable for solid state lighting and near ultra violet light emitting diodes (n-UV LED).Surface morphology has been also studied by scanning electron microscope and the room temperature FTIR spectrum for studying the nature of the chemical bonds, and their molecular environment was investigated.CIE(Commission Internationalede L'Eclairage) chromaticity coordinates values are estimated from emission spectra of BaCaP207:Eu2+ for the prepared sample

Kohale, R. L.; Dhoble, S. J.

2011-10-01

83

The Effect of Gravity on the Combustion Synthesis of Porous Biomaterials  

NASA Technical Reports Server (NTRS)

Production of highly porous composite materials by traditional materials processing is limited by difficult processing techniques. This work investigates the use of self propagating high temperature (combustion) synthesis (SHS) to create porous tricalcium phosphate (Ca3(PO4)2), TiB-Ti, and NiTi in low and microgravity. Combustion synthesis provides the ability to use set processing parameters to engineer the required porous structure suitable for bone repair or replacement. The processing parameters include green density, particle size, gasifying agents, composition, and gravity. The advantage of the TiB-Ti system is the high level of porosity achieved together with a modulus that can be controlled by both composition (TiB-Ti) and porosity. At the same time, NiTi exhibits shape memory properties. SHS of biomaterials allows the engineering of required porosity coupled with resorbtion properties and specific mechanical properties into the composite materials to allow for a better biomaterial.

Castillo, M.; Zhang, X.; Moore, J. J.; Schowengerdt, F. D.; Ayers, R. A.

2003-01-01

84

Combustion synthesis\\/densification of ceramics and ceramic composites. (Reannouncement with new availability information)  

Microsoft Academic Search

Combustion synthesis followed by densification was utilized in producing monolithic TiC and TiB2 materials, and TiC-Ni, TiB2-Ni, TiB2-Al2O3, and TiB2SiC ceramic composites. Static and dynamic densification equipments were developed with the loading applied immediately after the synthesis reaction was completed and the ceramic\\/composite was ductile. All the ceramics exhibited an equiaxed grain structure with alternating regions at high and low

M. A. Myers; J. C. LaSalvia; D. Hoke; J. M. Jamet; D. K. Kim

1992-01-01

85

The combustion synthesis of boride composites. [BâC\\/TiBâ infiltrated with Al  

Microsoft Academic Search

We have investigated the combustion synthesis process as a means of producing hard, tough, lightweight Bâc\\/TiBâ composites. We based our experimental program on thermodynamic calculations. Adiabatic temperatures and product compositions were determined on the basis of the stoichiometry and initial temperature of the reactants. For lightweight products the composition must be relatively rich in the BâC component. We found that

D. C. Halverson; B. Y. Lum; Z. A. Munir

1987-01-01

86

Combustion Synthesis of Ca3(PO4)2 Net-Shape Surgical Implants  

NASA Technical Reports Server (NTRS)

Self-propagating high-temperature combustion synthesis (SHS) is the basis of a method of making components of porous tricalcium phosphate [Ca3(PO4)2] and related compounds in net sizes and shapes for use as surgical implants that are compatible with bone. The SHS method offers advantages over prior methods of manufacturing Ca3(PO4)2-based surgical implants.

Ayers, Reed A.; Castillo, Martin; Gottoli, Guglielmo; Moore, John J.; Simske, Steven J.

2006-01-01

87

Self-propagating high-temperature synthesis for compound thermoelectrics and new criterion for combustion processing  

NASA Astrophysics Data System (ADS)

The existing methods of synthesis of thermoelectric (TE) materials remain constrained to multi-step processes that are time and energy intensive. Here we demonstrate that essentially all compound thermoelectrics can be synthesized in a single-phase form at a minimal cost and on the timescale of seconds using a combustion process called self-propagating high-temperature synthesis. We illustrate this method on Cu2Se and summarize key reaction parameters for other materials. We propose a new empirically based criterion for sustainability of the combustion reaction, where the adiabatic temperature that represents the maximum temperature to which the reacting compact is raised as the combustion wave passes through, must be high enough to melt the lower melting point component. Our work opens a new avenue for ultra-fast, low-cost, large-scale production of TE materials, and provides new insights into combustion process, which greatly broaden the scope of materials that can be successfully synthesized by this technique.

Su, Xianli; Fu, Fan; Yan, Yonggao; Zheng, Gang; Liang, Tao; Zhang, Qiang; Cheng, Xin; Yang, Dongwang; Chi, Hang; Tang, Xinfeng; Zhang, Qingjie; Uher, Ctirad

2014-09-01

88

Self-propagating high-temperature synthesis for compound thermoelectrics and new criterion for combustion processing.  

PubMed

The existing methods of synthesis of thermoelectric (TE) materials remain constrained to multi-step processes that are time and energy intensive. Here we demonstrate that essentially all compound thermoelectrics can be synthesized in a single-phase form at a minimal cost and on the timescale of seconds using a combustion process called self-propagating high-temperature synthesis. We illustrate this method on Cu2Se and summarize key reaction parameters for other materials. We propose a new empirically based criterion for sustainability of the combustion reaction, where the adiabatic temperature that represents the maximum temperature to which the reacting compact is raised as the combustion wave passes through, must be high enough to melt the lower melting point component. Our work opens a new avenue for ultra-fast, low-cost, large-scale production of TE materials, and provides new insights into combustion process, which greatly broaden the scope of materials that can be successfully synthesized by this technique. PMID:25223333

Su, Xianli; Fu, Fan; Yan, Yonggao; Zheng, Gang; Liang, Tao; Zhang, Qiang; Cheng, Xin; Yang, Dongwang; Chi, Hang; Tang, Xinfeng; Zhang, Qingjie; Uher, Ctirad

2014-01-01

89

Combustion synthesis of metallic foams from nanocomposite reactants  

Microsoft Academic Search

Highly porous intermetallic alloys were created through self-propagating high-temperature synthesis. The reactants are composed of nano-scale particles of nickel (Ni), micron-scale particles of aluminum (Al), and nano-scale Al particles passivated with a gasifying agent, C13F27COOH. The concentration of nano-Al particles present in the reactant matrix was controlled according to the wt% gasifying agent. Flame propagation was observed to transition from

Emily M. Hunt; Michelle L. Pantoya; R. Jason Jouet

2006-01-01

90

Microwave-Induced Combustion Synthesis of Hexagonal Barium Ferrite Powders  

Microsoft Academic Search

A novel ceramic synthesis technique, microwave-assisted process was investigated for the production of Barium Hexagonal ferrite (BaFe^Oip) powders with improved physical properties. Compared to conventional synthetic route, the new method significantly shortened synthetic steps and reaction time. This technique involves the reaction of stoichiometric amount of metal nitrates and appropriate dosage of citric acid at microwave oven and the whole

Dong Limin; Han Zhidong; Wu Ze; Zhang Xianyou

2007-01-01

91

Combustion  

NASA Technical Reports Server (NTRS)

An overview of the emissions related research being conducted as part of the Fundamental Aeronautics Subsonics Fixed Wing Project is presented. The overview includes project metrics, milestones, and descriptions of major research areas. The overview also includes information on some of the emissions research being conducted under NASA Research Announcements. Objective: Development of comprehensive detailed and reduced kinetic mechanisms of jet fuels for chemically-reacting flow modeling. Scientific Challenges: 1) Developing experimental facilities capable of handling higher hydrocarbons and providing benchmark combustion data. 2) Determining and understanding ignition and combustion characteristics, such as laminar flame speeds, extinction stretch rates, and autoignition delays, of jet fuels and hydrocarbons relevant to jet surrogates. 3) Developing comprehensive kinetic models for jet fuels.

Bulzan, Dan

2007-01-01

92

Synthesis, droplet combustion, and sooting characteristics of biodiesel produced from waste vegetable oils  

SciTech Connect

In light of the potential of fatty acid methyl ester (FAME, i.e. biodiesel) as a renewable energy source, an innovative acid catalyzed process was developed for the synthesis of biodiesel from waste vegetable oils. The synthesized biodiesels were analytically characterized for their major components, molar fraction and molecular weight of each component, the average molecular weight, and the heat of combustion. Their droplet combustion characteristics in terms of the burning rate, flame size, and sooting tendency were subsequently determined in a high-temperature, freely-falling droplet apparatus. Results show that the biodiesel droplet has higher burning rate, and that biodiesel in general has a lower propensity to soot because its molecular oxygen content promotes the oxidation of the soot precursors.

Li, T. X.; Zhu, D. L.; Akafuah, N.; Saito, K.; Law, C. K.

2011-01-01

93

Synthesis of the Nanocrystalline Nickel Ferrite by a Novel Mechano Sol-Gel Auto-Combustion Method  

NASA Astrophysics Data System (ADS)

In this work, a novel method of mechano sol-gel auto-combustion has been developed for production of single phase nickel ferrite nanocrystalline powder, consisting of a sol-gel auto-combustion synthesis followed by a high energy milling process before calcination. Sol-gel auto-combustion was carried out using a gel including citric acid as a reductant and metal nitrates as oxidants. This gel exhibited a self-propagating behavior after ignition in air. The effects of the intermediate high energy milling on the physical properties of the final product after calcination were investigated. The results showed that with a high energy milling of the sol-gel auto-combusted powders with a ball-to-powder mass ratio of 20 for 20 h, the temperature of calcination for synthesis of the single phase ferrite reduced from 1000°C to 700°C and the size of the ferrite crystallites decreased from 72 nm to 15 nm.

Shahmirzaei, M.; Seyyed Ebrahimi, S. A.; Dehghan, R.

94

Development of a novel combustion synthesis method for synthesizing of ceramic oxide powders  

Microsoft Academic Search

A novel combustion synthesis method has been developed to prepare electronic ceramic oxide powders—Ni0.5Zn0.5Fe2O4, ZnO, LiCoO2, BaFe12O19 and YBa2Cu3O7?x (x?0.25). Organic compounds (e.g., glycine, urea, citric acid, alanine, or carbohydrazide) to be mixed directly with metal nitrates without adding water, is the key technique of this method. Metal nitrates acting as oxidants were also used as cation sources, whereas an

Chyi-Ching Hwang; Tsung-Yung Wu; Jun Wan; Jih-Sheng Tsai

2004-01-01

95

Synthesis and sintering of nanocrystalline hydroxyapatite powders by citric acid sol-gel combustion method  

SciTech Connect

The citric acid sol-gel combustion method has been used for the synthesis of nanocrystalline hydroxyapatite (HAP) powder from calcium nitrate, diammonium hydrogen phosphate and citric acid. The phase composition of HAP powder was characterized by X-ray powder diffraction analysis (XRD). The morphology of HAP powder was observed by transmission electron microscope (TEM). The HAP powder has been sintered into microporous ceramic in air at 1200 deg. C with 3 h soaking time. The microstructure and phase composition of the resulting HAP ceramic were characterized by scanning electron microscope (SEM) and XRD, respectively. The physical characterization of open porosity and flexural strength have also been carried out.

Han Yingchao; Li Shipu; Wang Xinyu; Chen Xiaoming

2004-01-03

96

MINIMIZATION OF TOXIC COMBUSTION BYPRODUCTS: REVIEW OF CURRENT ACTIVITIES  

EPA Science Inventory

In general, toxic combustion byproducts (TCBS) are the unwanted residues remaining in flue gases, combustion ashes, and wastewaters from the operation of an incineration or combustion facility. f a combustor is not well designed and operated, it may emit too high a level of TCBS....

97

Synthesis and antimycobacterial activity of calpinactam derivatives.  

PubMed

Synthesis of calpinactam 1, a fungal antimycobacterial metabolite, utilizing solid-phase peptide synthesis is described. To explore the structure-activity relationships of 1, its derivatives with different amino acids were also synthesized on the basis of the same synthetic strategy. These derivatives were examined for antimycobacterial activity against Mycobacterium smegmatis. Among them, only peptide 6d having d-Ala in place of d-Glu showed moderate activity. PMID:23116887

Nagai, Kenichiro; Koyama, Nobuhiro; Sato, Noriko; Yanagisawa, Chisato; Tomoda, Hiroshi

2012-12-15

98

Combustion of Na 2B 4O 7 + Mg + C to synthesis B 4C powders  

NASA Astrophysics Data System (ADS)

Boron carbide powder was fabricated by combustion synthesis (CS) method directly from mixed powders of borax (Na 2B 4O 7), magnesium (Mg) and carbon. The adiabatic temperature of the combustion reaction of Na 2B 4O 7 + 6 Mg + C was calculated. The control of the reactions was achieved by selecting reactant composition, relative density of powder compact and gas pressure in CS reactor. The effects of these different influential factors on the composition and morphologies of combustion products were investigated. The results show that, it is advantageous for more Mg/Na 2B 4O 7 than stoichiometric ratio in Na 2B 4O 7 + Mg + C system and high atmosphere pressure in the CS reactor to increase the conversion degree of reactants to end product. The final product with the minimal impurities' content could be fabricated at appropriate relative density of powder compact. At last, boron carbide without impurities could be obtained after the acid enrichment and distilled water washing.

Guojian, Jiang; Jiayue, Xu; Hanrui, Zhuang; Wenlan, Li

2009-09-01

99

A synthesis of carbon dioxide emissions from fossil-fuel combustion  

SciTech Connect

This synthesis discusses the emissions of carbon dioxide from fossil-fuel combustion and cement production. While much is known about these emissions, there is still much that is unknown about the details surrounding these emissions. This synthesis explores 5 our knowledge of these emissions in terms of why there is concern about them; how they are calculated; the major global efforts on inventorying them; their global, regional, and national totals at different spatial and temporal scales; how they are distributed on global grids (i.e. maps); how they are transported in models; and the uncertainties associated with these different aspects of the emissions. The magnitude of emissions 10 from the combustion of fossil fuels has been almost continuously increasing with time since fossil fuels were first used by humans. Despite events in some nations specifically designed to reduce emissions, or which have had emissions reduction as a byproduct of other events, global total emissions continue their general increase with time. Global total fossil-fuel carbon dioxide emissions are known to within 10% uncertainty (95% 15 confidence interval). Uncertainty on individual national total fossil-fuel carbon dioxide emissions range from a few percent to more than 50 %. The information discussed in this manuscript synthesizes global, regional and national fossil-fuel carbon dioxide emissions, their distributions, their transport, and the associated uncertainties.

Andres, Robert Joseph [ORNL; Boden, Thomas A [ORNL; Breon, F.-M. [CEA/DSM/LSCE, Gif sur Yvette, France; Ciais, P. [LSCE/CEA, Gif-sur-Yvette, France; Davis, S. [Carnegie Institution of Washington; Erickson, D [Oak Ridge National Laboratory (ORNL); Gregg, J. S. [Riso National Laboratory, Roskilde, Denmark; Jacobson, Andrew [NOAA ESRL and CIRES; Marland, Gregg [Appalachian State University; Miller, J. [NOAA ESRL and CIRES; Oda, T [NOAA ESRL/Boulder, CO/Cooperative Institute for Research in the Atmosphere, Colorado State Univ.; Oliver, J. G. J. [PBL Netherlands Environmental Assessment Agency, Bilthoven, The Netherlands; Raupach, Michael [CSIRO Marine and Atmospheric Research; Rayner, P [University of Melbourne, Australia; Treanton, K. [Energy Statistics Division, International Energy Agency, Paris, France

2012-01-01

100

Joining of Ni-TiC FGM and Ni-Al Intermetallics by Centrifugal Combustion Synthesis  

SciTech Connect

A centrifugal combustion synthesis (CCS) process has been investigated to join a Ni-Al intermetallic compound and a Ni-TiC cermet. The cermet, a tubular graphite mold, and a green compact of reactants consisting of Al, Ni and NiO were set in a centrifugal caster. When the combustion synthesis reaction was induced in the centrifugal force field, a synthesized molten Ni-Al alloy flowed into the graphite mold and joined to the cermet. The soundness of the joint interface depended on the volume percentage of TiC phase in the cermet. A lot of defects were formed near the interface between the Ni-TiC cermet and the cast Ni-Al alloy when the volume percentage of TiC was 50% or higher. For this kind of cermet system, using a functionally graded cermet such as Ni-10 vol.%TiC/Ni-25 vol.%TiC/Ni-50 vol.%TiC overcame this difficulty. The four-point bending strength of the joined specimen consisting of the three-layered FGM cermet and cast Ni-29 mol%Al alloy was 1010 MPa which is close to the result for a Ni-29 mol%Al alloy specimen.

Ohmi, Tatsuya; Matsuura, Kiyotaka; Iguchi, Manabu [Hokkaido University, Kita 13, Nishi 8, Kita-ku, Sapporo, Hokkaido, 060-8628 (Japan); Mizuma, Kiminori [Graduate Student of Hokkaido University (Japan)

2008-02-15

101

Combustion characteristics and influential factors of isooctane active-thermal atmosphere combustion assisted by two-stage reaction of n-heptane  

SciTech Connect

This paper presents an experimental study on the isooctane active-thermal atmosphere combustion (ATAC) which is assisted by two-stage reaction of n-heptane. The active-thermal atmosphere is created by low- and high-temperature reactions of n-heptane which is injected at intake port, and isooctane is directly injected into combustion chamber near the top dead center. The effects of isooctane injection timing, active-thermal atmosphere intensity, overall equivalence ratio, and premixed ratio on combustion characteristics and emissions are investigated. The experimental results reveal that, the isooctane ignition and combustion can be classified to thermal atmosphere combustion, active atmosphere combustion, and active-thermal atmosphere combustion respectively according to the extent of n-heptane oxidation as well as effects of isooctane quenching and charge cooling. n-Heptane equivalence ratio, isooctane equivalence ratio and isooctane delivery advance angle are major control parameters. In one combustion cycle, the isooctane ignited and burned after those of n-heptane, and then this combustion phenomenon can also be named as dual-fuel sequential combustion (DFSC). The ignition timing of the overall combustion event is mainly determined by n-heptane equivalence ratio and can be controlled in flexibility by simultaneously adjusting isooctane equivalence ratio. The isooctane ignition regime, overall thermal efficiency, and NO{sub x} emissions show strong sensitivity to the fuel delivery advance angle between 20 CA BTDC and 25 CA BTDC. (author)

Lu, Xingcai; Ji, Libin; Ma, Junjun; Zhou, Xiaoxin; Huang, Zhen [Key Lab. for Power Machinery and Engineering of MOE, Shanghai Jiao Tong University, 200240 Shanghai (China)

2011-02-15

102

Effect Of Gravity On Porous Tricalcium Phosphate And Nonstoichiometric Titanium Carbide Produced Via Combustion Synthesis  

NASA Technical Reports Server (NTRS)

Novel processing techniques, such as self-propagating high temperature synthesis (SHS), have the capability to rapidly produce advanced porous materials that are difficult to fabricate by other methods. This processing technique is also capable of near net shape synthesis, while variable gravity allows the manipulation of the structure and composition of the material. The creation of porous tricalcium phosphate (TCP) is advantageous in the biomaterials field, since it is both a biocompatible material and an osteoconductive material. Porous tricalcium phosphate produced via SHS is an excellent candidate for bone scaffold material in the bone regeneration process. The porosity allows for great vascularization and ingrowth of tissue. Titanium Carbide is a nonstoichiometric biocompatible material that can be incorporated into a TiC-Ti composite system using combustion synthesis. The TiC-Ti composite exhibits a wide range of mechanical and chemical properties. Both of these material systems (TCP and TiC-Ti) can be used to advantage in designing novel bone replacement materials. Gravity plays an important role in both the pore structure and the chemical uniformity of these composite systems and offers considerable potential in advanced bone engineering.

Castillo, M.; Moore, J. J.; Schowengerdt, F. D.; Ayers, R. A.

2003-01-01

103

Synthesis and anticancer activity of epipolythiodiketopiperazine alkaloids  

E-print Network

Synthesis and anticancer activity of epipolythiodiketopiperazine alkaloids Nicolas Boyer,a Karen C (ETP) alkaloids are a highly complex class of natural products with potent anticancer activity. Herein Epipolythiodiketopiperazine (ETP)1 alkaloids constitute a large (ca. 120 members) and diverse family of biologically active

Hergenrother, Paul J.

104

Dynamical Processes in Active Control of Combustion Instabilities  

Microsoft Academic Search

Summary Strong coupling of combustion with pressure waves gives rise to oscillations and instabilities. Such dynamical phenomena raise difficult practical issues and their understanding and control constitute challenging scientific and technological problems. These topics have received considerable attention during the last period in relation with incidents encountered in gas turbines operating in the premixed mode. Combustion dynamics is also to

S. Candel; S. Ducruix; T. Schuller; D. Durox; F. Lacas

105

Optical filtering and luminescence property of some molybdates prepared by combustion synthesis  

NASA Astrophysics Data System (ADS)

As an important class of lanthanide inorganic compounds, rare earth ions doped molybdates have gained much attention due to their attractive luminescence and structural properties, supporting various promising applications as phosphor materials in the fields such as white light-emitting diodes, optical fibers, biolabel, lasers, and so on. The molybdate family has promising trivalent cation conducting properties and most of the optical properties result from electron transitions of the 4f shell, which are greatly affected by the composition and structures of rare-earth compounds. In this paper we report the molybdate CaMoO4:Eu3+ for red SSL and Bi1.4Y0.6MoO6, Y6MoO12 for optical filtering, prepared by one step combustion synthesis.

Yadav, P. J.; Joshi, C. P.; Moharil, S. V.

2014-10-01

106

Different toxic mechanisms are activated by emission PM depending on combustion efficiency  

NASA Astrophysics Data System (ADS)

Ambient air levels of fine particulate matter (PM ? 2.5 ?m) are associated with mortality and morbidity. In addition to traffic, large quantities of fine and ultrafine particles (UFPs ? 100 nm) are emitted by residential wood combustion. Polycyclic aromatic hydrocarbon (PAH) and soot-rich emissions from small scale heating appliances have been linked with a plethora of toxicological effects. Recently, new technology appliances have been introduced into use although there are several uncertainties related to the toxicological properties of those emissions. In this study, PM1 (PM ? 1 ?m) emissions from three different biomass combustion situations were compared. PM samples were produced in a novel adjustable biomass combustion reactor to avoid the problems encountered if one uses different appliances to generate the desired combustion conditions. The combustion conditions represented efficient, intermediate and smoldering situations. The concentration related effects of the particles (15, 50,150 and 300 ?g ml-1) were investigated in a RAW264.7 macrophage cell line after 24 h' exposure. We analyzed cellular metabolic activity, cell cycle, and indicators of genotoxicty, oxidative stress and proinflammatory responses. Interestingly, the particles collected from smoldering and intermediate combustion conditions decreased cellular metabolic activity less than those from efficient combustion (10-fold difference). However, the samples from intermediate and smoldering combustion evoked greater DNA damage in the comet assay (2.5-fold difference). In contrast, only the particulate samples from efficient combustion triggered G2-cell cycle arrest and oxidative stress in the macrophages. These results indicate that ash rich PM emissions from appliances with almost complete combustion may still exert health impacts. However, particulate emissions from efficient combustion were small when compared to the two other situations. Thus, even with their faults and the obvious need for development, consumers should be encouraged to purchase efficient combustion devices in order to reduce exposure to PM induced adverse health effects.

Uski, O.; Jalava, P. I.; Happo, M. S.; Leskinen, J.; Sippula, O.; Tissari, J.; Mäki-Paakkanen, J.; Jokiniemi, J.; Hirvonen, M.-R.

2014-06-01

107

Synthesis of Diamond Films on Molybdenum Substrate Surface by Combustion Flame  

NASA Astrophysics Data System (ADS)

Diamond films were synthesized on a Mo substrate using combustion flame. During the cooling process, most diamond films delaminated. From previous work it was shown that diamond films delaminated at a synthesis temperature less than 1300K (low temperature), and films did not delaminate at synthesis temperature more than 1400K (high temperature). In this study, to clarify the influences on the delamination of the interface, films synthesized at high temperature and low temperature were investigated by SEM and X-ray diffraction. The results show that in the case of low temperature, diamond films were synthesized on the Mo substrate, case of high temperature, Mo2C and diamond phases were synthesized on the Mo substrate. Thermally induced interfacial stress occurs due to the thermal expansion mismatch between the synthesized film and the Mo substrate. The interfacial stress by high temperature and low temperature was determined as the cause of the delamination. Thus, the interfacial stress of each synthesized temperature was calculated by a finite element method. The results show that the interfacial stress in the film synthesized by high temperature was smaller than that by the low temperature. As the buffer phases prevent the delamination, synthesized films by high temperature will be useful as hardcoating layer for a metal surface.

Takahashi, Mamoru; Kamiya, Osamu; Ohyoshi, Tadashi

108

Inverse peptide synthesis via activated ?-aminoesters.  

PubMed

A mild, practical, and simple procedure for peptide-bond formation is reported. Instead of activation of the carboxylic acid functionality, the reaction involves an unprecedented use of activated ?-aminoesters. The method provides a straightforward entry to dipeptides and was effective when a sensitive cysteine residue was used, as no epimerization was detected in this case. The applicability of this method to iterative peptide synthesis was illustrated by the synthesis of a model tetrapeptide in the challenging reverse N?C direction. PMID:24757099

Suppo, Jean-Simon; Subra, Gilles; Bergès, Matthieu; Marcia de Figueiredo, Renata; Campagne, Jean-Marc

2014-05-19

109

Synthesis of Diamond Film on Molybdenum Substrate Surface by Combustion Flame Considering the Delamination of the Interface  

NASA Astrophysics Data System (ADS)

Diamond films were synthesized on a Mo substrate using combustion flame. During cooling process, the most diamond films delaminated from the Mo substrate because of their thermal expansion mismatch. To prevent the delamination, a three-step synthesis method was proposed. The first step was synthesis of the Mo2C and the diamond phases on the Mo substrate, and the second and the third steps were synthesis of the diamond phase. The interfacial stress between the film and substrate was calculated by a finite element method. According to the results, the stress in the film made by the method was smaller than that by an one-step synthesis method. The three-step method is useful for synthesizing the diamond film.

Takahashi, Mamoru; Ito, Shunichi; Kamiya, Osamu; Ohyoshi, Tadashi

110

Combustion synthesis of ceramic-metal composite materials - The TiC-Al2O3-Al system  

NASA Technical Reports Server (NTRS)

Combustion synthesis was applied for producing ceramic-metal composites with reduced levels of porosity, by allowing an excess amount of liquid metal, generated by the exothermic reaction during synthesis, to infiltrate the pores. It is shown that this method, when applied to TiC-Al2O3 system, led to a decreased level of porosity in the resulting TiC-Al2O3-Al product, as compared with that of TiC-Al2O3 system. This in situ procedure is more efficient than the two-stage conventional processes (i.e., sintering followed by liquid metal infiltration), although there are limitations with respect to total penetration of the liquid metal and maintaining a stable propagation of the combustion reaction.

Feng, H. J.; Moore, John J.; Wirth, D. G.

1992-01-01

111

Differential Behavior of Combustion and Gasification Fly Ash from Puertollano Power Plants (Spain) for Zeolite Synthesis and Silica Extraction  

Microsoft Academic Search

Coal gasification (IGCC) and pulverised coal combustion (PCC) fly ashes (FAs), obtained from two power plants fed with the carboniferous bituminous coal from Puertollano (Spain), were characterized. Both FAs were used as raw materials for zeolite synthesis by direct conversion and by alkaline fusion, and SiO2 extraction at laboratory scale. The Puertollano FAs are characterised by a high SiO2 content

Natalia Moreno; Sergi Diez; Xavier Querol; Angel López-Soler; Pilar Coca; Francisco García Peña

112

Effective utilization of waste ash from MSW and coal co-combustion power plant: Zeolite synthesis.  

PubMed

The solid by-product from power plant fueled with municipal solid waste and coal was used as a raw material to synthesize zeolite by fusion-hydrothermal process in order to effectively use this type of waste material. The effects of treatment conditions, including NaOH/ash ratio, operating temperature and hydrothermal reaction time, were investigated, and the product was applied to simulated wastewater treatment. The optimal conditions for zeolite X synthesis were: NaOH/ash ratio=1.2:1, fusion temperature=550 degrees C, crystallization time=6-10 h and crystallization temperature=90 degrees C. In the synthesis process, it was found that zeolite X tended to transform into zeolite HS when NaOH/ash ratio was 1.8 or higher, crystallization time was 14-18 h, operating temperature was 130 degrees C or higher. The CEC value, BET surface area and pore volume for the synthesized product at optimal conditions were 250 cmol kg(-1), 249 m(2) g(-1) and 0.46 cm(3) g(-1) respectively, higher than coal fly ash based zeolite. Furthermore, when applied to Zn(2+) contaminated wastewater treatment, the synthesized product presented larger adsorption capacity and bond energy than coal fly ash based zeolite, and the adsorption isotherm data could be well described by Langmuir and Freundlich isotherm models. These results demonstrated that the special type of co-combustion ash from power plant is suitable for synthesizing high quality zeolite, and the products are suitable for heavy metal removal from wastewater. PMID:17913357

Fan, Yun; Zhang, Fu-Shen; Zhu, Jianxin; Liu, Zhengang

2008-05-01

113

Structural and spectroscopic analyses of europium doped yttrium oxyfluoride powders prepared by combustion synthesis  

SciTech Connect

A facile widely spread technique employed to produce low-cost high-yield oxide powders, combustion synthesis, was used to prepare yttrium oxyfluoride crystalline ceramic powders. The structure of the powders was analyzed by X-ray powder diffraction and Rietveld refinement. Samples heat treated at 700 °C had a predominance of vernier orthorhombic Y{sub 6}O{sub 5}F{sub 8} phase, while samples heat treated at 800 °C crystallized in stoichiometric rhombohedral YOF phase. The samples were doped with luminescent europium trivalent ions (Eu{sup 3+}) in different concentrations (1–15 wt.%) and Judd-Ofelt theory was used to probe the distortion from the inversion symmetry of the local crystal field and the degree of covalency between the rare-earth ion and the surrounding ligands. The luminescence lifetime was measured and the luminescence quantum efficiency (LQE) was estimated. We observed that Eu{sup 3+}:Y{sub 6}O{sub 5}F{sub 8} samples presented higher LQE in spite of the larger local crystal field anisotropy found for Eu{sup 3+}:YOF samples.

Rakov, Nikifor [PG-Ciência dos Materiais, Universidade Federal do Vale do São Francisco, 48902-300 Juazeiro, BA (Brazil)] [PG-Ciência dos Materiais, Universidade Federal do Vale do São Francisco, 48902-300 Juazeiro, BA (Brazil); Guimarães, R. B.; Maciel, Glauco S. [Instituto de Física, Universidade Federal Fluminense, 24210-346 Niterói, RJ (Brazil)] [Instituto de Física, Universidade Federal Fluminense, 24210-346 Niterói, RJ (Brazil); Lozano B, W. [Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, PE (Brazil)] [Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, PE (Brazil)

2013-07-28

114

Highly aluminium doped barium and strontium ferrite nanoparticles prepared by citrate auto-combustion synthesis  

SciTech Connect

Aluminium doped barium and strontium hexaferrite nanoparticles BaAl {sub x}Fe{sub (12-x)}O{sub 19} and SrAl {sub x}Fe{sub (12-x)}O{sub 19} were synthesised via a sol-gel route using citric acid to complex the ions followed by an auto-combustion reaction. This method shows promise for the synthesis of complex ferrite powders with small particle size. It was found that around half of the iron could be substituted for aluminium in the barium ferrite with structure retention, whereas strontium aluminium ferrites could be produced with any aluminium content including total substitution of the iron. All synthesised materials consisted of particles smaller than 1 {mu}m, which is the size of a single magnetic domain, and various doping levels were achieved with the final elemental composition being within the bounds of experimental error. The materials show structural and morphological changes as they move from iron to aluminium ferrites. Such materials may be promising for imaging applications.

Shirtcliffe, Neil J. [Nottingham Trent University, Clifton Lane, Clifton, Nottingham NG11 8NS (United Kingdom)]. E-mail: neil.shirtcliffe@ntu.ac.uk; Thompson, Simon [Nottingham Trent University, Clifton Lane, Clifton, Nottingham NG11 8NS (United Kingdom); O'Keefe, Eoin S. [QinetiQ, Farnborough, Hampshire (United Kingdom); Appleton, Steve [QinetiQ, Farnborough, Hampshire (United Kingdom); Perry, Carole C. [Nottingham Trent University, Clifton Lane, Clifton, Nottingham NG11 8NS (United Kingdom)]. E-mail: carole.perry@ntu.ac.uk

2007-02-15

115

Synthesis and Antibacterial Activities of Yanglingmycin Analogues.  

PubMed

The synthesis of Yanglingmycin and its enantiomer, along with eighteen Yanglingmycin analogues is reported. The structures were confirmed mainly by analyses of NMR spectral data. Antibacterial activity assays showed that Yanglingmycin and some of its analogues exhibited significant antibacterial activities against two important agricultural pathogenic bacteria, Ralstonia solanacearum and Pseudomonas syringae pv. actinidiae, with MIC values ranging from 3.91 to 15.62 ?g/mL. The antibacterial activities exhibited by Yanglingmycin and its analogues are promising, suggesting potential in the development of compounds for novel bactericides. PMID:25355464

Li, Long-Bo; Dan, Wen-Jia; Tan, Fang-Fang; Cui, Li-Hui; Yuan, Zhi-Peng; Wu, Wen-Jun; Zhang, Ji-Wen

2014-10-30

116

Preparation and dielectric properties of B-doped SiC powders by combustion synthesis  

SciTech Connect

The SiC(B) solid solution powders were synthesized via combustion reaction of Si/C system in Ar atmosphere, using boron powder as the dopant and polytetrafluoroethylene as the chemical activator, which were investigated by X-ray diffraction (XRD), scanning electronic microscope (SEM) and Raman spectra. Results show that the prepared powders are C-enriched SiC with C antisites and sp{sup 2} carbon defects in which the sp{sup 2} carbon is transformed to the sp{sup 3} carbon due to boron doping. The electric permittivities of the prepared powders were determined in the frequency range of 8.2-12.4 GHz. The dielectric real part {epsilon}' and dielectric loss tan {delta} of undoped powder have maximum values ({epsilon}' = 5.5-5.3, tan {delta} = 0.23-0.20), and decrease with increasing boron content. The mechanism of dielectric loss by doping has been discussed.

Su Xiaolei [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an shaanxi 710072 (China)], E-mail: suxlei@163.com; Zhou Wancheng; Li Zhimin; Luo Fa; Du Hongliang; Zhu Dongmei [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an shaanxi 710072 (China)

2009-04-02

117

Combustion synthesis of TiO2-Al-C/Al2O3 mixture in the presence of oxygen  

NASA Astrophysics Data System (ADS)

Quasi-adiabatic combustion synthesis of optimized 3TiO2+4Al+(3+x)C mixture in the presence of oxygen was carried out to produce TiC-Al2O3 composite. The influence of Al2O3 diluent in combusted (3TiO2+4Al+3.5C+yAl2O3) reactant mixture was investigated. Thermodynamics studies of the system shown that self-sustaining (SS) mode of combustion wave propagation can occur for large amounts of diluents (y = 2.5). Diluent reduced combustion temperature and rate of reaction kinetics. Oxide (Ti2O, Ti3O5) and intermetallic (AlTi2) phases were detected when extra Al2O3 was added to the mixture. Semi-quantitative XRD analysis was employed to study the phase formation of products for various amounts of diluent content in the mixture. The boundary between SS and non-SS modes of wave propagation was determined. Adding Al2O3 diluent slightly increased density that resulted in better thermal conductivity.

Rahbari G, R.; Saw, L. H.; Hamdi, M.; Yahya, R.

2009-03-01

118

Differential behaviour of combustion and gasification fly ash from Puertollano Power Plants (Spain) for the synthesis of zeolites and silica extraction.  

PubMed

Coal gasification (IGCC) and pulverised coal combustion (PCC) fly ashes (FAs), obtained from two power plants fed with the carboniferous bituminous coal from Puertollano (Spain), were characterised and used as raw materials for zeolite synthesis by direct conversion (DC) and by alkaline fusion (Fu), and SiO2 extraction (Si-Ex) at laboratory scale. The Puertollano FAs are characterised by a high SiO2 content (59%) with respect to EU coal FAs. High zeolite synthesis yields were obtained from both FAs by using conventional alkaline activation. However, the Si extraction yields were very different. The results of the zeolite synthesis from the Si-bearing extracts from both FAs demonstrated that high purity zeolites with high cation exchange capacity (CEC, between 4.3 and 5.3meq/g) can be produced. The solid residue arising from Si-Ex is also a relatively high NaP1 zeolite product (CEC 2.4-2.7 meq/g) equivalent to the DC products. The zeolitic materials synthesised from both FAs by Fu showed an intermediate (between the high purity zeolites and the DC products) zeolite content with CEC values from 3.4 to 3.7 meq/g. Low leachable metal contents were obtained from high purity A and X zeolites and zeolite material synthesised by Fu for PCC FA. PMID:19097700

Font, O; Moreno, N; Díez, S; Querol, X; López-Soler, A; Coca, P; Peña, F García

2009-07-15

119

Personalized implant for high tibial opening wedge: combination of solid freeform fabrication with combustion synthesis process.  

PubMed

In this work a new generation of bioceramic personalized implants were developed. This technique combines the processes of solid freeform fabrication (SFF) and combustion synthesis (CS) to create personalized bioceramic implants with tricalcium phosphate (TCP) and hydroxyapatite (HA). These porous bioceramics will be used to fill the tibial bone gap created by the opening wedge high tibial osteotomy (OWHTO). A freeform fabrication with three-dimensional printing (3DP) technique was used to fabricate a metallic mold with the same shape required to fill the gap in the opening wedge osteotomy. The mold was subsequently used in a CS process to fabricate the personalized ceramic implants with TCP and HA compositions. The mold geometry was designed on commercial 3D CAD software. The final personalized bioceramic implant was produced using a CS process. This technique was chosen because it exploits the exothermic reaction between P?O? and CaO. Also, chemical composition and distribution of pores in the implant could be controlled. To determine the chemical composition, the microstructure, and the mechanical properties of the implant, cylindrical shapes were also fabricated using different fabrication parameters. Chemical composition was performed by X-ray diffraction. Pore size and pore interconnectivity was measured and analyzed using an electronic microscope system. Mechanical properties were determined by a mechanical testing system. The porous TCP and HA obtained have an open porous structure with an average 400?µm channel size. The mechanical behavior shows great stiffness and higher load to failure for both ceramics. Finally, this personalized ceramic implant facilitated the regeneration of new bone in the gap created by OWHTO and provides additional strength to allow accelerated rehabilitation. PMID:21750185

Zhim, Fouad; Ayers, Reed A; Moore, John J; Moufarrège, Richard; Yahia, L'Hocine

2012-09-01

120

Combustion Synthesis of Nanoparticulate LiMgxMn1-xPO4 (x=0, 0.1, 0.2) Carbon Composites  

SciTech Connect

A combustion synthesis technique was used to prepare nanoparticulate LiMgxMn1-xPO4 (x=0, 0.1,0.2)/carbon composites. Powders consisted of carbon-coated particles about 30 nm in diameter, which were partly agglomerated into larger secondary particles. The utilization of the active materials in lithium cells depended most strongly upon the post-treatment and the Mg content, and was not influenced by the amount of carbon. Best results were achieved with a hydrothermally treated LiMg0.2Mn0.8PO4/C composite, which exhibited close to 50percent utilization of the theoretical capacity at a C/2 discharge rate.

Doeff, Marca M; Chen, Jiajun; Conry, Thomas E.; Wang, Ruigang; Wilcox, James; Aumentado, Albert

2009-12-14

121

Modeling of combustion instabilities and their active control in a gas fueled combustor  

Microsoft Academic Search

This study deals with the development of simplified models for simulation of combustion instabilities and their active control. Modulation of a part of the fuel supply is used to damp instabilities by generating heat release oscillations that are out of phase with the existing pressure oscillations. A model that accounts for mixing using a heuristic source term has been developed,

Rajendran Mohanraj

1998-01-01

122

Combustion synthesis and luminescent properties of metal yttrium borates M3Y2 (BO3)4:Eu3+ (M = Ba, Sr) for PDPs applications  

NASA Astrophysics Data System (ADS)

The polycrystalline powder samples of Eu3+ activated; mixed metal yttrium borate phosphors M3Y2(BO3)4 (M = Ba, Sr) with improved color purity of red emission for plasma display panels (PDPs) were prepared by solution combustion technique. The synthesis is based up on the exothermic reaction between the fuel (Urea) and oxidizer (Ammonium nitrate) .The heat generated in the reaction is utilized for auto combustion of ingredients. The formation of desired product and crystal structure was confirmed by powder XRD technique; while particle morphology was studied using FE-SEM. Samples under 254 and 147 nm excitation showed intense and pure red emission around 613 nm corresponding to the electric dipole 5D0 ? 7F2 transition of Eu3+, CIE chromaticity coordinates of synthesized phosphors was found to be (x = 0.67, y = 0.32) close to National Television Standard Committee (NTSC) for red color; found suitable to employ in plasma display panels (PDPs) applications.

Ingle, J. T.; Sonekar, R. P.; Omanwar, S. K.; Wang, Yuhua; Zhao, Lei

2014-07-01

123

Highly Selective Synthesis of Catalytically Active Monodisperse Rhodium Nanocubes  

SciTech Connect

Synthesis of monodisperse and shape-controlled colloidal inorganic nanocrystals (NCs) is of increasing scientific interest and technological significance. Recently, shape control of Pt, Pd, Ag, Au, and Rh NCs has been obtained by tuning growth kinetics in various solution-phase approaches, including modified polyol methods, seeded growth by polyol reduction, thermolysis of organometallics, and micelle techniques. Control of reduction kinetics of the noble metal precursors and regulation of the relative growth rates of low-index planes (i.e. {l_brace}100{r_brace} and {l_brace}111{r_brace}) via selective adsorption of selected chemical species are two keys for achieving shape modification of noble metal NCs. One application for noble metal NCs of well-defined shape is in understanding how NC faceting (determines which crystallographic planes are exposed) affects catalytic performance. Rh NCs are used in many catalytic reactions, including hydrogenation, hydroformylation, hydrocarbonylation, and combustion reactions. Shape manipulation of Rh NCs may be important in understanding how faceting on the nanoscale affects catalytic properties, but such control is challenging and there are fewer reports on the shape control of Rh NCs compared to other noble metals. Xia and coworkers obtained Rh multipods exhibiting interesting surface plasmonic properties by a polyol approach. The Somorjai and Tilley groups synthesized crystalline Rh multipods, cubes, horns and cuboctahedra, via polyol seeded growth. Son and colleagues prepared catalytically active monodisperse oleylamine-capped tetrahedral Rh NCs for the hydrogenation of arenes via an organometallic route. More recently, the Somorjai group synthesized sizetunable monodisperse Rh NCs using a one-step polyol technique. In this Communication, we report the highly selective synthesis of catalytically active, monodisperse Rh nanocubes of < 10 nm by a seedless polyol method. In this approach, Br{sup -} ions from trimethyl(tetradecyl)ammonium bromide (TTAB) effectively stabilize the {l_brace}100{r_brace} faces of Rh NCs, and induce the evolution of nanocubes (Scheme 1). For a typical synthesis, 0.2 mmol RhCl{sub 3} hydrate, 1 mmol TTAB, and 4 mmol poly(vinylpyrrolidone) (PVP, Mw = 24,000), were added to 20 ml ethylene glycol at room temperature. The stock solution was heated to 80 C and purged for 20 min while stirring, producing a dark brown solution. The flask was then heated to 185 C and maintained at this temperature for 1.5 h under an Ar atmosphere. When the reaction was complete, an excess of acetone was added to the solution at room temperature to precipitate the nanocubes. The Rh nanocubes were separated by centrifugation and washed twice by precipitation/dissolution with ethanol/hexanes.

Zhang, Y.; Grass, M.E.; Kuhn, J.N.; Tao, F.; Habas, S.E.; Huang, W.; Yang, P.; Somorjai, G.A.

2009-02-21

124

Synthesis of thermostable geopolymer from circulating fluidized bed combustion (CFBC) bottom ashes.  

PubMed

Circulating fluidized bed combustion (CFBC) bottom ashes (CBAs) are a class of calcined aluminosilicate wastes with a unique thermal history. While landfill disposal of hazardous element-containing CBAs poses serious challenge, these wastes have long been neglected as source materials for geopolymer production. In this paper, geopolymerization of ground CBAs was investigated. Reactivity of the CBAs was analyzed by respective dissolution of the ashes in 2, 5, and 10N NaOH and KOH solutions. Geopolymer pastes were prepared by activating the CBAs by a series of alkalis hydroxides and/or sodium silicate solutions. Samples were cured at 40 degrees C for 168 h, giving a highest compressive strength of 52.9 MPa. Of the optimal specimen, characterization was conducted by TG-DTA, SEM, XRD, as well as FTIR analyses, and thermal stability was determined in terms of compressive strength evolution via exposure to 800 or 1050 degrees C followed by three cooling regimes, i.e. cooling in air, cooling in the furnace, and immerging in water. The results show that CBAs could serve as favorable source materials for thermostable geopolymers, which hold a promise to replace ordinary Portland cement (OPC) and organic polymers in a variety of applications, especially where fire hazards are of great concern. PMID:19879690

Xu, Hui; Li, Qin; Shen, Lifeng; Wang, Wei; Zhai, Jianping

2010-03-15

125

Combustion synthesis/quasi-isostatic pressing of TiC0.7NiTi cermets: microstructure and transformation characteristics  

E-print Network

Combustion synthesis/quasi-isostatic pressing of TiC0.7­NiTi cermets: microstructure Abstract TiC0.7­NiTi cermets were produced by com- bustion synthesis followed by quasi-isostatic consolidation while the reaction products were still hot and ductile. The TiC0.7­NiTi cermets were characterized

Meyers, Marc A.

126

Synthesis of barium hexaferrite nano-particles via mechano-combustion route  

Microsoft Academic Search

Nano-size particles of barium hexaferrite have been synthesized by what is termed mechano-combustion after milling of intermediate products obtained in the sol–gel combustion process using nitrate–citrate gels prepared from metal nitrates and citric acid. The effects of precursor milling conditions on the phase evolution, crystallite size and annealing behavior of the products were investigated using XRD technique.The XRD results indicate

A. Ataie; S. E. Zojaji

2007-01-01

127

Synthesis and characterization of nanosized titanium particles by gas-phase combustion  

Microsoft Academic Search

Nanosized titanium particles are produced by gas-phase combustion under low-temperature. Combustion behavior of a TiCl4–Na mixture in a flow of argon was investigated by coflow flame method depending on the processing parameters such as burner shape, argon pressure and temperature. The nanosized titanium particles of 20–100nm covered by a thin layer of NaCl were obtained at the flame temperatures of

Duck-Young Maeng; Chang-Kyu Rhee; Kyeong-Ho Kim; Whung-Whoe Kim

2004-01-01

128

Magneto-thermal and dielectric properties of biferroic YCrO{sub 3} prepared by combustion synthesis  

SciTech Connect

Microstructural, magnetothermal and dielectric properties of YCrO{sub 3} powders prepared by combustion and solid state methods have been studied by a combination of XRD, specific heat, magnetization and permittivity measurements. The TEM and XRD characterization confirm that the combustion powders are amorphous plate-like agglomerates of nano-sized crystalline particles. A more uniform grain size along with an increase of the relative density is observed by SEM in the sintered samples prepared by combustion route with respect to those produced by solid state reaction. Similar to the material obtained through solid state synthesis, the material prepared by the combustion method also shows spin canted antiferromagnetic ordering of Cr{sup +3} (S=3/2) at {approx}140 K, which is shown by magnetization as well as {lambda}-type anomaly in the total specific heat. Furthermore, the magnetic contribution to the total specific heat reveals spin fluctuations above T{sub N} and a spin reorientation transition at about 60 K. Both YCrO{sub 3} compounds show a diffuse phase transition at about 450 K, typical of a relaxor ferroelectric, which is characterized by a broad peak in the real part of the dielectric permittivity as a function of temperature, with the peak decreasing in magnitude and shifting to higher temperature as the frequency increases. The relaxor dipoles are due to the local non-centrosymmetric structure. Furthermore, the high loss tangent in a broad range of temperature as well as conductivity analysis indicates a hopping mechanism for the electronic conductivity as we believe it is a consequence of the outer d{sup 3}-shell, which have detrimental effects on the polarization and the pooling process in the YCrO{sub 3} bulk material. The more uniform particle size and higher density material synthesized through the combustion process leads to an improvement in the dielectric Properties. - Graphical abstract: Combustion method: An alternative route for synthesized a new family of multiferroics. Amorphous agglomerates of nano-sized particles of YCrO{sub 3} compounds.

Duran, A., E-mail: dural@cnyn.unam.m [Universidad Nacional Autonoma de Mexico, Centro de Nanociencias y Nanotecnologia, Apartado Postal 2681, C.P. 22800, Ensenada, B.C. (Mexico); Arevalo-Lopez, A.M.; Castillo-Martinez, E. [Departamento de Quimica Inorganica y Laboratorio Complutense de Altas Presiones, Facultad de Quimica, Universidad Complutense de Madrid, E.U., 28040 Madrid (Spain); Garcia-Guaderrama, M. [Centro de Investigacion en Materiales DIP-CUCEI, Universidad de Guadalajara. Av. Revolucion 1500, Col. Olimpica, Guadalajara (Mexico); Moran, E. [Departamento de Quimica Inorganica y Laboratorio Complutense de Altas Presiones, Facultad de Quimica, Universidad Complutense de Madrid, E.U., 28040 Madrid (Spain); Cruz, M.P. [Universidad Nacional Autonoma de Mexico, Centro de Nanociencias y Nanotecnologia, Apartado Postal 2681, C.P. 22800, Ensenada, B.C. (Mexico); Fernandez, F. [Universidad Politecnica de Madrid, E.U. Ingenieria Tecnica Industrial, Ronda de Valencia, 3, E-28012 Madrid (Spain); Alario-Franco, M.A. [Departamento de Quimica Inorganica y Laboratorio Complutense de Altas Presiones, Facultad de Quimica, Universidad Complutense de Madrid, E.U., 28040 Madrid (Spain)

2010-08-15

129

Efficient catalysis by MgCl2 in hydrogen generation via hydrolysis of Mg-based hydride prepared by hydriding combustion synthesis.  

PubMed

Magnesium chloride efficiently catalyzed the hydrolysis of Mg-based hydride prepared by hydriding combustion synthesis. Hydrogen yield of 1635 mL g(-1) was obtained (MgH(2)), i.e. with 96% conversion in 30 min at 303 K. PMID:22538836

Zhao, Zelun; Zhu, Yunfeng; Li, Liquan

2012-06-01

130

New combustion synthesis technique for the production of (InxGa1-x)2O3 powders: Hydrazine/metal nitrate method  

E-print Network

/metal nitrate method R. Garci´a and G.A. Hirata Programa de Posgrado en Fi´sica de Materiales CICESE by a more typical combustion synthesis reaction between nitrates and a carbonaceous fuel at a higher exothermic reaction occurs between metal nitrates and a carbonaceous reductive fuel, resulting in a porous

McKittrick, Joanna

131

Synthesis of nanocrystalline NiAl by mechanically activated self-propagating high-temperature synthesis and mechanically activated annealing process  

NASA Astrophysics Data System (ADS)

The mechanically activated self-propagating high-temperature synthesis (MASHS) technique and the mechanically activated annealing process (M2AP) were used to produce NiAl intermetallic compound. Rietveld analysis of X-ray diffraction data was used to characterize the mechanically activated powders, MASHS and M2AP end-products. Two-phase (B2+L12) nickel aluminide intermetallic compounds were synthesized by the mechanically activated volume combustion synthesis (MASHS). A single phase B2 NiAl was formed when mechanically activated annealing process (M2AP) was performed. Starting from a mixture of elemental pure powders, both M2AP and MASHS milling processes lead to nanostructured powders. Structural analysis deduced from the Rietveld refinement of X-ray diffraction patterns of NiAl compounds synthesized by SHS after a milling of 6 h show the formation of ?-NiAl phase with a cell parameter a = (0.2885 ± 1.2618 × 10-4) nm. The average crystallite size is D = (44.6421 ± 2.4263) nm and the microstrains values are close to those of metallic alloys ? = (0.2142 ± 1.6186 × 10-2)%. Finally, scanning electron microscopy (SEM) was carried out to characterize the microstructure of end-products.

Arroussi, Soumia; Ali-Rachedi, Mahieddine; Chemam, Abdelbaki; Benaldjia, Abdelaziz; Amara, Abdelaziz; Gasmi, Brahim; Andasmas, Mohamed; Guerioune, Mohamed

2013-12-01

132

: Synthesis, Characterization, and Enhanced Photocatalytic Activity  

NASA Astrophysics Data System (ADS)

3D hierarchical microspheres of Cu-loaded Bi2WO6 are successfully prepared by the hydrothermal synthesis method on a large scale. The as-prepared samples are characterized by UV-Vis DRS, BET, XRD, XPS, and SEM. The results reveal that the light absorption of Cu-loaded Bi2WO6 has higher intensity in the visible range and a bathochromic shift of the absorption edge compared to that of pure Bi2WO6. The photocatalytic activity is evaluated by phenol removal from aqueous solution under visible-light irradiation. The results demonstrate that loaded Cu significantly enhances the photocatalytic activity of Bi2WO6, for the loaded Cu acts as the electron receptor on the surface of Bi2WO6, and inhibits the recombination of photogenerated electron-hole. The content of loaded Cu has an impact on the catalytic activity, and the 1.0 wt.% Cu-loaded Bi2WO6 exhibits the best photocatalytic activity in the degradation of phenol. Furthermore, the reaction kinetics of phenol removal from aqueous solution over the Cu-loaded Bi2WO6 is established by the way of the Langmuir-Hinshelwood model. The results indicate that the process of photodegradation of phenol on Cu-loaded Bi2WO6 match the Langmuir-Hinshelwood kinetic model.

Gao, Xiaoming; Fu, Feng; Li, Wenhong

2014-12-01

133

The Effects of Gravity on the Combustion Synthesis of B2O3-Al2O3-MgO Glass Ceramic Composites  

NASA Technical Reports Server (NTRS)

Glass ceramic composites based on B2O3-Al2O3-MgO have been produced by combustion synthesis in a Self-propagating mode. The gravitational effects on the combustion characteristics such as combustion wave velocity (V), and combustion temperature (T(sub c)) were studied. The results showed that the gravitational effects on these parameters were inconclusive. The microstructure of this system has also been analyzed with X-ray Diffraction and light microscopy. These results showed a higher amount of divitrification occurs under both reduced gravity and high gravity conditions. The gravitational effects on formation of pores, overall porosity and apparent porosity for this family of glass-ceramics also shows to be inconclusive. Possible reasons for these results are discussed.

Manerbino, A. R.; Yi, H. C.; Guigne, J. Y.; Moore, J. J.; Schowengerdt, F. D.

2000-01-01

134

Performance Evaluation of a High Bandwidth Liquid Fuel Modulation Valve for Active Combustion Control  

NASA Technical Reports Server (NTRS)

At the NASA Glenn Research Center, a characterization rig was designed and constructed for the purpose of evaluating high bandwidth liquid fuel modulation devices to determine their suitability for active combustion control research. Incorporated into the rig s design are features that approximate conditions similar to those that would be encountered by a candidate device if it were installed on an actual combustion research rig. The characterized dynamic performance measures obtained through testing in the rig are planned to be accurate indicators of expected performance in an actual combustion testing environment. To evaluate how well the characterization rig predicts fuel modulator dynamic performance, characterization rig data was compared with performance data for a fuel modulator candidate when the candidate was in operation during combustion testing. Specifically, the nominal and off-nominal performance data for a magnetostrictive-actuated proportional fuel modulation valve is described. Valve performance data were collected with the characterization rig configured to emulate two different combustion rig fuel feed systems. Fuel mass flows and pressures, fuel feed line lengths, and fuel injector orifice size was approximated in the characterization rig. Valve performance data were also collected with the valve modulating the fuel into the two combustor rigs. Comparison of the predicted and actual valve performance data show that when the valve is operated near its design condition the characterization rig can appropriately predict the installed performance of the valve. Improvements to the characterization rig and accompanying modeling activities are underway to more accurately predict performance, especially for the devices under development to modulate fuel into the much smaller fuel injectors anticipated in future lean-burning low-emissions aircraft engine combustors.

Saus, Joseph R.; DeLaat, John C.; Chang, Clarence T.; Vrnak, Daniel R.

2012-01-01

135

Combustion synthesis process for the rapid preparation of high-purity SrO powders  

NASA Astrophysics Data System (ADS)

A rapid, safe and simple technique for the production of high purity strontium oxide powders via a chemical combustion process is reported. The combustion reactions were performed to optimize the fuel to oxidizer ratios in the reaction mixtures required to obtain pure SrO powders by varying the molar ratio of chemical precursors and the temperature. The synthesized powders were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectrometry, infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and N2-physisorption measurements. The results indicate that crystalline SrO was obtained using a 1:1 strontium nitrate: urea molar ratio at 1000 °C after 5 minutes. In addition, high-purity, homogeneous and crystalline SrO powders were easily produced in a short time via a chemical combustion process.

Granados-Correa, Francisco; Bonifacio-Martínez, Juan

2014-12-01

136

Causes of Combustion Instabilities with Passive and Active Methods of Control for practical application to Gas Turbine Engines  

NASA Astrophysics Data System (ADS)

Combustion at high pressure in applications such as rocket engines and gas turbine engines commonly experience destructive combustion instabilities. These instabilities results from interactions between combustion heat release, fluid mechanics and acoustics. This research explores the significant affect of unstable fluid mechanics processes in augmenting unstable periodic combustion heat release. The frequency of the unstable heat release may shift to match one of the combustors natural acoustic frequencies which then can result in significant energy exchange from chemical to acoustic energy resulting in thermoacoustic instability. The mechanisms of the fluid mechanics in coupling combustion to acoustics are very broad with many varying mechanisms explained in detail in the first chapter. Significant effort is made in understanding these mechanisms in this research in order to find commonalities, useful for mitigating multiple instability mechanisms. The complexity of combustion instabilities makes mitigation of combustion instabilities very difficult as few mitigation methods have historically proven to be very effective for broad ranges of combustion instabilities. This research identifies turbulence intensity near the forward stagnation point and movement of the forward stagnation point as a common link in what would otherwise appear to be very different instabilities. The most common method of stabilization of both premixed and diffusion flame combustion is through the introduction of swirl. Reverse flow along the centerline is introduced to transport heat and chemically active combustion products back upstream to sustain combustion. This research develops methods to suppress the movement of the forward stagnation point without suppressing the development of the vortex breakdown process which is critical to the transport of heat and reactive species necessary for flame stabilization. These methods are useful in suppressing the local turbulence at the forward stagnation point, limiting dissipation of heat and reactive species significantly improving stability. Combustion hardware is developed and tested to demonstrate the stability principles developed as part of this research. In order to more completely understand combustion instability a very unique method of combustion was researched where there are no discrete points of combustion initiation such as the forward stagnation point typical in many combustion systems including swirl and jet wake stabilized combustion. This class of combustion which has empirical evidence of great stability and efficient combustion with low CO, NOx and UHC emissions is described as high oxidization temperature distributed combustion. This mechanism of combustion is shown to be stable largely because there are no stagnations points susceptible to fluid mechanic perturbations. The final topic of research is active combustion control by fuel modulation. This may be the only practical method of controlling most instabilities with a single technique. As there are many papers reporting active combustion control algorithms this research focused on the complexities of the physics of fuel modulation at frequencies up to 1000 Hz with proportionally controlled flow amplitude. This research into the physics of high speed fluid movement, oscillation mechanical mechanisms and electromagnetics are demonstrated by development and testing of a High Speed Latching Oscillator Valve.

Cornwell, Michael D.

137

Reduced-order modeling and active control of dry-low-emission combustion  

NASA Astrophysics Data System (ADS)

This dissertation is a complementary experimental and theoretical investigation of combustion instability and lean blowout (LBO) in dry-low-emission (DLE) gas turbine engines, aiming to understand the fundamental mechanisms and shed light on active combustion control. Combustion instability involves complicated physicochemical processes, and many of the underlying mechanisms remain unknown, despite extensive research in the past several decades. A practical control system must be able to achieve satisfactory control performances in the presence of large uncertainties, large variations, and even unknown system dynamics. Toward this goal, an observer-based controller, capable of attenuating multiple unstable modes with unknown characteristics, is developed. A mechanism suitable for online prediction of the safety margin to the onset of combustion instability is presented, which does not require knowing the unstable frequencies. The shortage of a reliable, high-frequency, proportional fuel actuator is a major technical challenge for active combustion control. A complementary theoretical and experimental study is performed on a pump-style, high-frequency, magnetostrictive fuel actuator. Improvements to the fuel setup have been made according to the model predictions, which have been experimentally shown to be beneficial to combustion instability control. The second part of this dissertation is about modeling, prediction, and control of lean blowout. The experimentally observed, "intensified", low frequency, near-LBO combustion oscillations have been used as incipient LBO precursors, and are characterized as low-dimension chaotic behavior in the present study. The normalized chemiluminescence RMS and the normalized cumulative duration of LBO precursor events are recommended for LBO prediction in generic gas turbine engines. Linear stability analysis shows that, with decreasing equivalence ratios, a complex conjugate pair of eigenvalues emerges from three negative real ones, moves left toward the right half phase plane, and finally crosses the imaginary axis. Model predictions qualitatively and even quantitatively match the experiments. Simulation of the nonlinear WSR models shows the "triggered instability" which is similar to that in rocket motors. It is numerically demonstrated that zero-mean small-amplitude fuel modulations based on modern feedback control principles, can be very effective in strengthening the flame's robustness to external disturbances without exacerbating the overall emissions. Experimental demonstrations are suggested for future research.

Yi, Tongxun

138

Test Plan for Measuring Ventilation Rates and Combustible Gas Levels in TWRS Active Catch Tanks  

SciTech Connect

The purpose of this sampling activity is to obtain data to support an initial evaluation of potential hazards due to the presence of combustible gas in catch tanks that are currently operated by the River Protection Project (RPP). Results of the hazard analysis will be used to support closure of the flammable gas unreviewed safety question for these facilities. The data collection will be conducted in accordance with the Tank Safety Screening Data Quality Objective (Dukelow et al. 1995). Combustible gas, ammonia, and organic vapor levels in the headspace of the catch tanks will be field-measured using hand-held instruments. If a combustible gas level measurement in a tank exceeds an established threshold, gas samples will he collected in SUMMA' canisters for more extensive laboratory analysis. In addition, ventilation rates of some catch tanks will be measured to evaluate removal of flammable gas by air flowing through the tanks. This test plan identifies the sample collection, laboratory analysis, quality assurance, and reporting objectives for this data collection effort. The plan also provides the procedures for field measurement of combustible gas concentrations and ventilation rates.

NGUYEN, D.M.

1999-10-25

139

Test Plan for Measuring Ventilation Rates and Combustible Gas Levels in TWRS Active Catch Tanks  

SciTech Connect

The purpose of this data collection activity is to obtain data for a screening of combustible gases in catch tanks that are currently operated by the River Protection Project (RPP). The results will be used to support closure of the flammable gas unreviewed safety question for these facilities. The data collection will be conducted in accordance with the ''Tank Safety Screening Data Quality Objective'' (Dukelow et al. 1995). Combustible gas, ammonia, and organic vapor levels in the headspace of the catch tanks will be field-measured using hand-held instruments. If a combustible gas level measurement in a tank exceeds an established threshold, vapor grab samples (i.e., Hoke and SUMMA) will be collected for laboratory analysis. In addition, ventilation rates of some catch tanks will be determine using the tracer gas injection method to evaluate removal of flammable gas by air flowing through the tanks. This test plan identifies the field tests, sample collection, laboratory analysis, quality assurance, and reporting objectives for this data collection effort. The plan also provides step-by-step direction for field measurement of combustible gas concentrations and determination of ventilation rates.

NGUYEN, D.M.

2000-03-01

140

Powder synthesis and characterization of nanocrystalline CeO{sub 2} via the combustion processes  

SciTech Connect

Nanocrystalline CeO{sub 2} powders were synthesized by the combustion reactions using citric acid and glycol as fuels and nitrate as an oxidant. The adiabatic flame temperatures in the auto ignition processes of the precursors were calculated theoretically. XRD measurements indicated that the powders produced in the combustion processes were cubic fluorite CeO{sub 2} phase. The size and morphology of the particles and extent of agglomeration in the powders were studied using transmission electron microscopy (TEM) and the particle size analyzer respectively. Blue shifts of the absorption peak of the as-prepared powders were observed.

Gu Lina [Department of Material Science and Engineering, University of Science and Technology of China, 230026 Hefei (China) and School of Chemistry and Chemical Engineering, Anhui University, 230039 Hefei (China)]. E-mail: gln@mail.ustc.edu.cn; Meng Guangyao [Department of Material Science and Engineering, University of Science and Technology of China, 230026 Hefei (China)

2007-07-03

141

Catalytic activity of rare earth oxides in flameless methane combustion  

Microsoft Academic Search

The following rare earth oxides, which were prepared by the precipitation of hydroxides, were studied as catalysts for the\\u000a reaction of complete methane oxidation: CeO2, a hydrated phase of La2O3, Pr6O11, Tb4O7, and Gd2O3. The catalytic activities of the oxides were compared in terms of first-order reaction rate constants per unit surface area\\u000a of the catalyst. With consideration for data

A. V. Vishnyakov; I. A. Korshunova; V. E. Kochurikhin; L. S. Sal’nikova

2010-01-01

142

The combustion synthesis of boride composites. [B/sub 4/C/TiB/sub 2/ infiltrated with Al  

SciTech Connect

We have investigated the combustion synthesis process as a means of producing hard, tough, lightweight B/sub 4/c/TiB/sub 2/ composites. We based our experimental program on thermodynamic calculations. Adiabatic temperatures and product compositions were determined on the basis of the stoichiometry and initial temperature of the reactants. For lightweight products the composition must be relatively rich in the B/sub 4/C component. We found that B/sub 4/C-rich composites could only be obtained by increasing the initial temperature of the reactants. The product is a hard, porous material whose toughness should be enhanced by filling the pores with aluminum using a liquid-metal infiltration process. 9 figs., 3 tabs.

Halverson, D.C.; Lum, B.Y.; Munir, Z.A.

1987-10-01

143

Sol-gel auto-combustion synthesis of zinc ferrite for moderate temperature desulfurization  

SciTech Connect

Zinc ferrite as a desulfurization sorbent with an average crystallite size of about 36 nm was synthesized by a sol-gel auto-combustion method. The precursor for the sorbent was a gel obtained from metal nitrates and citric acid by a sol process. The nitrate-citrate gel exhibits a self-propagating combustion behavior, and after combustion, it can transform into a nanosized spinel structured zinc ferrite directly. The prepared sorbent has a larger specific surface area and higher reactivity when compared with the sorbent achieved by a solid mixing method, and it could efficiently reduce the H{sub 2}S concentration from 6000 ppm to less than 2 ppm at a moderate temperature range. The sulfur capacity at 400{sup o}C reaches about 38.5 g of sulfur/100 g of sorbent, which corresponds to 96.4% of the theoretical value. The temperature programmed oxidation test for the sulfided sorbent shows that the most sulfur is desorbed before 500{sup o}C. XRD results confirm that the sulfided sample after exposure to a 5% O{sub 2}/N{sub 2} gas mixture at 500{sup o}C can be regenerated completely, which indicates that the regeneration temperature of the sorbent prepared by the sol-gel auto-combustion method could be greatly reduced. 40 refs., 10 figs., 2 tabs.

Rongjun Zhang; Jiejie Huang; Jiantao Zhao; Zhiqiang Sun; Yang Wang [Chinese Academy of Sciences, Taiyuan (China). Institute of Coal Chemistry

2007-09-15

144

Synthesis of La{sup 3+} doped nanocrystalline ceria powder by urea-formaldehyde gel combustion route  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer Nano LC synthesized by gel combustion, using urea-formaldehyde fuel for first time. Black-Right-Pointing-Pointer Largely single crystals were produced in average range of 20-30 nm. Black-Right-Pointing-Pointer La{sup 3+} doping increases cell dimension linearly. Black-Right-Pointing-Pointer La{sup 3+} doping introduces ionic point defects but does not change electronic band gap. Black-Right-Pointing-Pointer Presence of Ce{sup 3+} indicates that this synthesis route produces reactive powders. -- Abstract: Nanocrystalline ceria powders doped with various concentrations of lanthanum oxide have been prepared following gel combustion route using for the first time urea-formaldehyde as fuel. The synthesized products were characterized by XRD, FESEM, TEM, PL and UV-vis spectroscopy. Peak positions of XRD were refined and the lattice parameters were obtained by applying Cohen's method. Unit cell parameter increases with concentration of La{sup 3+} ion and the variation is consistently linear. XRD calculations showed the dependence of crystallite size on dopant concentrations at lower level. TEM observation revealed unagglomerated particles to be single crystals in the average range of 20-30 nm. Band gap of the La{sup 3+} doped ceria materials does not change with doping. Spectroscopic experiments proved the existence of Ce{sup 3+} in the formed powder.

Biswas, M. [Central Glass and Ceramic Research Institute, Kolkata 700 032 (India)] [Central Glass and Ceramic Research Institute, Kolkata 700 032 (India); Bandyopadhyay, S., E-mail: sbando@cgcri.res.in [Central Glass and Ceramic Research Institute, Kolkata 700 032 (India)

2012-03-15

145

Synthesis and Anticancer Activity of All Known (-)-Agelastatin Sunkyu Han,  

E-print Network

Synthesis and Anticancer Activity of All Known (-)-Agelastatin Alkaloids Sunkyu Han, Dustin S-by-side evaluation of all known (-)-agelastatin alkaloids against nine human cancer cell lines are described. Our concise synthesis of these alkaloids exploits the intrinsic chemistry of plausible biosynthetic precursors

Hergenrother, Paul J.

146

On the effects of organic matter and sulphur-containing compounds on the CCN activation of combustion particles  

NASA Astrophysics Data System (ADS)

The European PartEmis project (Measurement and prediction of emissions of aerosols and gaseous precursors from gas turbine engines) was focussed on the characterisation and quantification of exhaust emissions from a gas turbine engine. The combustion aerosol characterisation included on-line measurements of mass and number concentration, size distribution, mixing state, thermal stability of internally mixed particles, hygroscopicity, cloud condensation nuclei (CCN) activation potential, and off-line analysis of chemical composition. Based on this extensive data set, the role of sulphuric acid coating and of the organic fraction of the combustion particles for the CCN activation was investigated. Modelling of CCN activation was conducted using microphysical and chemical properties obtained from the measurements as input data. Coating the combustion particles with water-soluble sulphuric acid, increases the potential CCN activation, or lowers the activation diameter, respectively. The adaptation of a Köhler model to the experimental data yielded coatings from 0.1 to 3 vol-% of water-soluble matter, which corresponds to an increase in the fraction of CCN-activated combustion particles from ?10-4 to ?10-2 at a water vapour saturation ratio Sw=1.006. Additional particle coating by coagulation of combustion particles and aqueous sulphuric acid particles formed by nucleation further reduces the CCN activation diameter. In contrast, particles containing a large fraction of non-volatile organic compounds grow significantly less at high relative humidity than particles with a lower content of non-volatile OC. The resulting reduction in the potential CCN activation with an increasing fraction of non-volatile OC becomes visible as a trend in the experimental data. While a coating of water-soluble sulphuric acid increases the potential CCN activation, or lowers the activation diameter, respectively, the non-volatile organic compounds, mainly found at lower combustion temperatures, can partially compensate this sulphuric acid-related enhancement of CCN activation of carbonaceous combustion aerosol particles.

Petzold, A.; Gysel, M.; Vancassel, X.; Hitzenberger, R.; Puxbaum, H.; Vrochticky, S.; Weingartner, E.; Baltensperger, U.; Mirabel, P.

2005-12-01

147

Synthesis of antimony-doped tin oxide (ATO) nanoparticles by the nitrate-citrate combustion method  

SciTech Connect

Antimony-doped tin oxide (ATO) nanoparticles having rutile structure have been synthesized by the combustion method using citric acid (CA) as fuel and nitrate as an oxidant, the metal sources were granulated tin and Sb{sub 2}O{sub 3}. The influence of citric acid (fuel) to metal ratio on the average crystallite size, specific surface area and morphology of the nanoparticles has been investigated. X-ray diffraction showed the tin ions were reduced to elemental tin during combustion reaction. The average ATO crystallite size increased with the increase of citric acid (fuel). Powder morphology and the comparison of crystallite size and grain size shows that the degree of agglomeration of the powder decreased with an increase of the ratio. The highest specific surface area was 37.5 m{sup 2}/g when the citric acid to tin ratio was about 6.

Zhang Jianrong [State Key Lab of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Gao Lian [State Key Lab of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)]. E-mail: Liangaoc@online.sh.cn

2004-12-02

148

Synthesis and characterization of Ba 2YSbO 6 nanoparticles through a modified combustion process  

Microsoft Academic Search

Nanoparticles of Yttrium Barium Antimonate (Ba2YSbO6), a complex perovskite ceramic oxide have been synthesized using an auto ignition combustion process for the first time. The particle size and properties of the nanocrystals have been characterized by X-ray diffraction, thermo gravimetric analysis, differential thermal analysis, Fourier transform infrared spectroscopy, scanning electron microscopy and transmission electron microscopy. The XRD studies have shown

C. Vijayakumar; H. Padma Kumar; Jijimon K. Thomas; P. R. S. Wariar; J. Koshy

2007-01-01

149

Combustion synthesis of rod-like ?-SiAlON seed crystals  

Microsoft Academic Search

Rod-like single-phase crystals of Y-?-SiAlON were synthesized by combustion of Si, Al, ?-Si3N4, SiO2 and Y2O3 powders. SEM observation of crystals, separated by chemical etching (HNO3\\/HF=2:1) followed by ultrasonic agitation in ethanol showed rod-like crystals, assigned to almost pure and well crystallized ?-SiAlON.

Renli Fu; Kexin Chen; Xin Xu; José M. F. Ferreira

2004-01-01

150

New Synthesis of Ferrite–Silica Nanocomposites by a Sol–Gel Auto-Combustion  

Microsoft Academic Search

A sol–gel autocombustion method was used to synthesize nanometric metal-oxide powders, and was extended for the first time to prepare ferrite–silica nanocomposites. The gels obtained by mixing suitable amounts of citric acid, metal nitrates, ammonia (pure phases) and tetraethylortosilicate (nanocomposites) were converted directly to ferrite (either ?-Fe2O3 or CoFe2O4) or ferrite–silica composites through a rapid autocombustion reaction. The combustion involves

C. Cannas; A. Musinu; D. Peddis; G. Piccaluga

2004-01-01

151

Combustion synthesis and photoluminescence of Nd 3+-doped YPO 4 nanocrystals  

Microsoft Academic Search

Nd3+-doped YPO4 nanocrystals were synthesized by combustion method with urea as a fuel calcined at 600°C. The diffraction profile of the obtained sample was indexed as a tetragonal xenotime structure by X-ray diffraction (XRD) data. The obtained nanocrystals appeared to be spherical with some agglomeration and their sizes ranged from 30 to 50nm. The luminescence intensities of Nd3+-doped YPO4 nanocrystals

Suwen Liu; Zhiliang Xiu; Fengxiu Xu; Weina Yu; Jiaoxian Yu; Guangjian Feng

2008-01-01

152

Combustion synthesis and photoluminescence of Eu3+ doped LaAlO3 nanophosphors  

NASA Astrophysics Data System (ADS)

Eu3+ doped LaAlO3 nanophosphors were successfully synthesized by a combustion process using concentrated solution of lanthanum nitrates and aluminate as oxidiser, and glycine acid as fuel. The powders were characterized by infrared spectroscopy (IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and fluorescence spectroscopy. Pure LaAlO3 phase was obtained at 800 °C heated for 4 h, without formation of any intermediate phase, with an average crystal size, as determined by TEM, of 60 nm. Intense photoluminescence emission is reported at 616 nm, allowing the use of this material as red phosphor.

Dhahri, A.; Horchani-Naifer, K.; Benedetti, A.; Enrichi, F.; Ferid, M.

2012-09-01

153

Differential behaviour of combustion and gasification fly ash from Puertollano Power Plants (Spain) for the synthesis of zeolites and silica extraction  

Microsoft Academic Search

Coal gasification (IGCC) and pulverised coal combustion (PCC) fly ashes (FAs), obtained from two power plants fed with the carboniferous bituminous coal from Puertollano (Spain), were characterised and used as raw materials for zeolite synthesis by direct conversion (DC) and by alkaline fusion (Fu), and SiO2 extraction (Si-Ex) at laboratory scale. The Puertollano FAs are characterised by a high SiO2

N. Moreno; S. Díez; X. Querol; A. López-Soler; P. Coca; F. García Peña

2009-01-01

154

Production and evaluation of dense ceramic compounds by combustion synthesis and dynamic compaction. Final report, 1 October 1988-31 August 1992  

Microsoft Academic Search

The objectives of this research program were to apply combustion synthesis and dynamic forging in order to produce fully dense ceramics. The program was successfully carried out but was unfortunately terminated. TiC and TiB2 ceramics, TiC-Ni cermets, and A12O3-TiB2 an TiB2-SiC ceramic-ceramic composites were successfully produced and characterized. Th research effort carried out from October 1988 to the present yielded

M. A. Meyers; J. C. LaSalvia; D. Hoke

1993-01-01

155

Near-infrared quantum cutting in Ce3+, Er3+, and Yb3+ doped yttrium silicate powders prepared by combustion synthesis  

NASA Astrophysics Data System (ADS)

Yttrium silicate (YS) powders doped with Ce3+, Er3+, and Yb3+ were prepared by combustion synthesis. The material was investigated for use as energy downconverters to reduce thermalization losses in crystalline Si solar cells. The powders were excited by UV light (355 nm), and near-infrared emission around 1 ?m was observed corresponding to a quantum cutting (QC) effect. The QC process occurs via cooperative energy transfer from Ce3+ (sensitizer) to Yb3+ (activator) in Ce3+:Yb3+ co-doped YS powders. QC was also observed in Er3+:Yb3+ co-doped YS powder via sequential energy transfer. The idea of synergy by use of Ce3+:Er3+:Yb3+ triply doped system to enhance the QC efficiency was investigated. We observed that the QC performance of Ce3+:Er3+:Yb3+ triply doped YS powder is not superior to that of Ce3+:Yb3+ co-doped YS powder due to near-infrared luminescence quenching induced by energy back-transfer from Yb3+ to Er3+.

Rakov, Nikifor; Maciel, Glauco S.

2011-10-01

156

Combustion synthesis, structural characterization, thermo and photoluminescence studies of CdSiO?:Dy³? nanophosphor.  

PubMed

CdSiO(3):Dy(3+) (1-9mol%) nanophosphors were prepared for the first time using the solution combustion method. The process of monoclinic phase formation was investigated by PXRD, TG-DTA and FTIR. The results show that the phase formation temperature of combustion-derived monoclinic CdSiO(3) is found to be lower as compared to the powders prepared by solid-state and sol-gel methods. It was observed that the average crystallite size calculated by Debye-Scherrer's formula and Williamson-Hall (W-H) plot are well comparable and was found to be in the range of 35-70 nm. Scanning electron micrographs indicate that there exist circular microcrystalline particles. It is observed that the optical energy gap is widened with the increase of Dy(3+) ion dopant. The photoluminescence (PL) spectra exhibit characteristic transitions of Dy(3+) due to (4)F(9/2)?(6)H(15/2) (blue) and (4)F(9/2)?(6)H(13/2) (yellow) regions. The thermoluminescence (TL) glow curve of CdSiO(3):Dy(3+) nano powder exposed to UV irradiation exhibited one main peak centered at 170°C. The intensity of the main peak increases up to the dose of 20 min then it decreases. The glow curves were analyzed by the glow peak shape method and the estimated trap parameters are discussed. PMID:22481172

Manjunatha, C; Sunitha, D V; Nagabhushana, H; Nagabhushana, B M; Sharma, S C; Chakradhar, R P S

2012-07-01

157

Novel combustion method to prepare octahedral NiO nanoparticles and its photocatalytic activity  

SciTech Connect

Graphical abstract: - Highlights: • NiO nanoparticles were synthesized by solution combustion method. • Prepared NiO nanoparticles are fcc structure. • Synthesized NiO nanoparticles are octahedral shape. • Shows good photocatalytic activity. - Abstract: Nickel oxide nanoparticles (NiO NPs) were synthesized by solution combustion method using glycine and citric acid as fuels. The X-ray diffraction (XRD) result confirms the face centered cubic (fcc) structure of NiO. The octahedral shape of NiO NPs was confirmed by field emission scanning electron microscope (FESEM) and high resolution transmission electron microscopy (HRTEM). It is possible to suggest that the organic fuel (citric acid/glycine) is responsible for the formation of the octahedral shape due to the easier complex formation. Photocatalytic activity of NiO NPs also evaluated and found that the prepared NiO NPs have high photocatalytic degradation. In the present study, the crystalline nature and shape of the NiO nanoparticles plays a vital role in determining the photocatalytic activity.

Jegatha Christy, A.; Umadevi, M., E-mail: ums10@yahoo.com

2013-10-15

158

Combustion synthesis and engineering of nanoparticles for electronic, structural and superconductor applications  

SciTech Connect

Fully dense, nanocrystalline ceramic articles were prepared by the new nanofabrication process. The process consists of two steps: synthesis of ceramic nanoparticles and fabrication of dense, nanocrystalline ceramic parts. The synthesis step produced 10-nanometer-diameter crystallites, and is capable of being scaled up to kilogram/hour production rates. The fabrication step produced dense parts at significantly reduced sintering temperatures and times -- representing a factor of 10--100 reduction in process energy requirements. The process was demonstrated by producing ultrafine-grained yttria-stabilized ZrO[sub 2], an important material with a variety of energy-related applications (solid electrolytes, oxygen sensors, electrode materials, thermal barrier coatings, etc.). Results from this period clearly illustrate the capabilities of this energy-efficient and directly commercializable process for producing dense, nanocrystalline, multicomponent oxide ceramics.

Stangle, G.C.; Amarakoon, V.R.W.; Schulze, W.A.

1993-05-28

159

Synthesis of cobalt ferrite (CoFe2O4) nanoparticles using combustion, coprecipitation, and precipitation methods: A comparison study of size, structural, and magnetic properties  

NASA Astrophysics Data System (ADS)

In this work the cobalt ferrite (CoFe2O4) nanoparticles are synthesized using three different methods; combustion, coprecipitation, and precipitation. Size, structural, and magnetic properties were determined and compared using X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM). XRD data analysis showed an average size of 69.5 nm for combustion, 49.5 nm for coprecipitation, and 34.7 nm for precipitation samples which concorded with SEM images. XRD data further revealed a reverse cubic spinel structure with the space group Fd-3m in all three samples. VSM data of samples showed a saturation point in the magnetic field of less than 15 kOe. Magnetization saturation (Ms) was 56.7 emu/g for combustion synthestized samples, 55.8 emu/g for coprecipitation samples, and 47.2 emu/g for precipitation samples. Coercivity (Hc) was 2002 Oe for combustion synthestized samples, 850 Oe for coprecipitation samples, and 233 Oe for precipitation samples. These results show that various methods of nanoparticle synthesis can lead to different particle sizes and magnetic properties. Hc and Ms are greatest in the combustion method and least in precipitation method.

Houshiar, Mahboubeh; Zebhi, Fatemeh; Razi, Zahra Jafari; Alidoust, Ali; Askari, Zohreh

2014-12-01

160

Nuclear-grade zirconium prepared by combining combustion synthesis with molten-salt electrorefining technique  

NASA Astrophysics Data System (ADS)

Zirconium has a low absorption cross-section for neutrons, which makes it an ideal material for use in nuclear reactor applications. However, hafnium typically contained in zirconium causes it to be far less useful for nuclear reactor materials because of its high neutron-absorbing properties. In the present study, a novel effective method has been developed for the production of hafnium-free zirconium. The process includes two main stages: magnesio-thermic reduction of ZrSiO 4 under a combustion mode, to produce zirconium silicide (ZrSi), and recovery of hafnium-free zirconium by molten-salt electrorefining. It was found that, depending on the electrorefining procedure, it is possible to produce zirconium powder with a low hafnium content: 70 ppm, determined by ICP-AES analysis.

Li, Hui; Nersisyan, Hayk H.; Park, Kyung-Tae; Park, Sung-Bin; Kim, Jeong-Guk; Lee, Jeong-Min; Lee, Jong-Hyeon

2011-06-01

161

Exploratory combustion synthesis: amorphous indium yttrium oxide for thin-film transistors.  

PubMed

We report the implementation of amorphous indium yttrium oxide (a-IYO) as a thin-film transistor (TFT) semiconductor. Amorphous and polycrystalline IYO films were grown via a low-temperature solution process utilizing exothermic "combustion" precursors. Precursor transformation and the IYO films were analyzed by differential thermal analysis, thermogravimetric analysis, X-ray diffraction, atomic force microscopy, X-ray photoelectron spectroscopy, and optical transmission, which reveal efficient conversion to the metal oxide lattice and smooth, transparent films. a-IYO TFTs fabricated with a hybrid nanodielectric exhibit electron mobilities of 7.3 cm(2) V(-1) s(-1) (T(anneal) = 300 °C) and 5.0 cm(2) V(-1) s(-1) (T(anneal) = 250 °C) for 2 V operation. PMID:22625409

Hennek, Jonathan W; Kim, Myung-Gil; Kanatzidis, Mercouri G; Facchetti, Antonio; Marks, Tobin J

2012-06-13

162

Solution combustion method for synthesis of nanostructured hydroxyapatite, fluorapatite and chlorapatite  

NASA Astrophysics Data System (ADS)

Hydroxyapatite (HAP), fluorapatite (Fap) and chlorapatite (Clap) were prepared by solution combustion method with further annealing at 800 °C. The characterization and structural features of the synthesized powders were evaluated by the powder X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and transmission electron microscopy (TEM) techniques. Characterization results from XRD and Rietveld analysis revealed that OH- in the HAP lattice were gradually substituted with the increase of F- and Cl- content and totally substituted at the molar concentration of 0.28 and 0.6, respectively. The results from FI-IR have also confirmed the incorporation of substituted anions in the apatite structure.

Zhao, Junjie; Dong, Xiaochen; Bian, Mengmeng; Zhao, Junfeng; Zhang, Yao; Sun, Yue; Chen, JianHua; Wang, XuHong

2014-09-01

163

Model-Based, Multiscale Self-Tuning Controller Developed for Active Combustion Control  

NASA Technical Reports Server (NTRS)

New challenges concerning system health-monitoring and life-extending robust controls for the Ultra-Efficient Engine Technology Project, as well as other advanced engine and power system concepts at NASA and elsewhere, have renewed the control community s interest in smart, model-based methods. In particular, these challenges have further motivated efforts at the NASA Glenn Research Center to exploit the versatility and superiority of the dynamic features extraction of multiscale analysis for controls--such as with "wavelets" and "wavelet filter-banks.' The accomplishments reported herein pertain to the active suppression of combustion instabilities in liquid-fuel combustors via fuel modulation. The fundamentals and initial success of this innovation were reported for a unique demonstration of active combustion control (a research collaboration of NASA Glenn with Pratt & Whitney and the United Technologies Research Center, UTRC). This demonstration, conducted in 2002 at UTRC on the NASA single nozzle rig (SNR) combustor, was the first known suppression of high-frequency instability with a liquid-fueled combustor. The SNR is based on a high-powered military engine combustor that exhibited well-known instabilities.

Le, Dzu K.

2005-01-01

164

Combustion front dynamics in the combustion synthesis of refractory metal carbides and di-borides using time-resolved X-ray diffraction.  

PubMed

A compact diffraction-reaction chamber, using a 2-inch photodiode array detector, has been employed to investigate the chemical dynamics at the combustion front of a selected series of refractory metal carbides and di-borides from their constituent element reactants as well as binary products from B4C as a reactant. These systems are denoted as (i) M + C --> MC; (ii) M + 2B --> MB2; and (iii) 3M + B4C --> 2MB2 + MC, where M = Ti, Zr, Nb, Hf or Ta. Time-resolved X-ray diffraction using intense synchrotron radiation at frame rates up to 10 frames s(-1) (or 100 ms frame(-1)) was employed. The combustion reactions were found to complete within 200-400 ms. In contrast to the Ta + C --> TaC combustion system studied earlier, in which a discernible intermediate sub-carbide phase was first formed, reacted further and disappeared to yield the final TaC product, no intermediate sub-carbide or sub-boride was detected in the current systems. Combustion for the Ti, Zr and Hf systems involved a liquid phase, in which the adiabatic temperatures Tad are well above the melting points of the respective reactant metals and have a typical combustion front velocity of 5-6 mm s(-1). The Nb and Ta systems have lower Tad, involving no liquid phase. These are truly solid combustion systems and have a lower combustion front velocity of 1-2 mm s(-1). The current study opens up a new avenue to chemical dynamics and macrokinetic investigations of high-temperature solid-state reactions. PMID:16799224

Wong, Joe; Larson, E M; Waide, P A; Frahm, R

2006-07-01

165

A microwave-assisted solution combustion synthesis to produce europium-doped calcium phosphate nanowhiskers for bioimaging applications.  

PubMed

Biocompatible nanoparticles possessing fluorescent properties offer attractive possibilities for multifunctional bioimaging and/or drug and gene delivery applications. Many of the limitations with current imaging systems center on the properties of the optical probes in relation to equipment technical capabilities. Here we introduce a novel high aspect ratio and highly crystalline europium-doped calcium phosphate nanowhisker produced using a simple microwave-assisted solution combustion synthesis method for use as a multifunctional bioimaging probe. X-ray diffraction confirmed the material phase as europium-doped hydroxyapatite. Fluorescence emission and excitation spectra and their corresponding peaks were identified using spectrofluorimetry and validated with fluorescence, confocal and multiphoton microscopy. The nanowhiskers were found to exhibit red and far red wavelength fluorescence under ultraviolet excitation with an optimal peak emission of 696 nm achieved with a 350 nm excitation. Relatively narrow emission bands were observed, which may permit their use in multicolor imaging applications. Confocal and multiphoton microscopy confirmed that the nanoparticles provide sufficient intensity to be utilized in imaging applications. PMID:23764803

Wagner, Darcy E; Eisenmann, Kathryn M; Nestor-Kalinoski, Andrea L; Bhaduri, Sarit B

2013-09-01

166

EPR investigation on synthesis of Lithium zinc vanadate using sol-gel-combustion route and its optical properties  

NASA Astrophysics Data System (ADS)

The present work describes the synthesis of Lithium zinc vanadate (LiZnVO4) nanophosphor prepared by sol-gel-combustion method and its optical properties. The prepared sample was characterized by X-ray diffraction, SEM, electron paramagnetic resonance and photoluminescence spectroscopy. X-ray diffraction study showed the formation of pure LiZnVO4 at 600 °C with distorted phenacite structure. SEM investigation revealed that the phosphor powder has spherical morphology with particle size of about 100-200 nm. EPR study showed the change of coordination sphere around vanadium from axially distorted octahedral symmetry to tetrahedral geometry along with the change in oxidation state of vanadium ion from +4 to +5. The emission spectrum showed a broad emission at 543 nm with ?ex = 375 nm. The decay time obtained on mono-exponential fitting was 8.3 ?s. The colour coordinates of the system were evaluated using CIE index diagram to be 0.31 and 0.41, which suggest that the prepared material is a potential green emitting phosphor. A bright green colour emission was also observed directly from this phosphor upon excitation with an UV source.

Pathak, Nimai; Gupta, Santosh K.; Prince, Angelina; Kadam, R. M.; Natarajan, V.

2014-01-01

167

Aqueous Combustion Synthesis of Aluminum Oxide Thin Films and Application as Gate Dielectric in GZTO Solution-Based TFTs.  

PubMed

Solution processing has been recently considered as an option when trying to reduce the costs associated with deposition under vacuum. In this context, most of the research efforts have been centered in the development of the semiconductors processes nevertheless the development of the most suitable dielectrics for oxide based transistors is as relevant as the semiconductor layer itself. In this work we explore the solution combustion synthesis and report on a completely new and green route for the preparation of amorphous aluminum oxide thin films; introducing water as solvent. Optimized dielectric layers were obtained for a water based precursor solution with 0.1 M concentration and demonstrated high capacitance, 625 nF cm(-2) at 10 kHz, and a permittivity of 7.1. These thin films were successfully applied as gate dielectric in solution processed gallium-zinc-tin oxide (GZTO) thin film transistors (TFTs) yielding good electrical performance such as subthreshold slope of about 0.3 V dec(-1) and mobility above 1.3 cm(2) V(-1) s(-1). PMID:25354332

Branquinho, Rita; Salgueiro, Daniela; Santos, Lídia; Barquinha, Pedro; Pereira, Luís; Martins, Rodrigo; Fortunato, Elvira

2014-11-26

168

Activation of catalysts for synthesizing methanol from synthesis gas  

DOEpatents

A method for activating a methanol synthesis catalyst is disclosed. In this method, the catalyst is slurried in an inert liquid and is activated by a reducing gas stream. The activation step occurs in-situ. That is, it is conducted in the same reactor as is the subsequent step of synthesizing methanol from a methanol gas stream catalyzed by the activated catalyst still dispersed in a slurry.

Blum, David B. (108 Tall Oaks Dr., Wayne, NJ 07470); Gelbein, Abraham P. (45 Headley Rd., Morristown, NJ 07960)

1985-01-01

169

Managing creative projects: An empirical synthesis of activities  

Microsoft Academic Search

This paper proposes a radical empirical look on the concrete activities of project managers involved in creative projects, with a specific focus on “non-administrative” issues. Through four case studies in the video-game industry, multimedia, advertising and a circus, we propose an integrated synthesis of what creative project managers actually do. Beyond analytical, cognitive, psychological, symbolic and discursive activities, we identify

Laurent Simon

2006-01-01

170

Study of wear between piston ring and cylinder housing of an internal combustion engine by thin layer activation technique  

Microsoft Academic Search

The wear analysis of a compression ring and cylinder housing of an Internal Combustion Engine by thin layer activation (TLA) with 40 MeV alpha-particles from the Variable Energy Cyclotron at Calcutta is reported. The calibration curves have been obtained for Fe and Ni using stacked foil activation technique for determining the absolute wear in these machine parts. It has been

D. P. Chowdhury; Jayanta Chaudhuri; V. S. Raju; S. K. Das; B. B. Bhattacharjee; S. Gangadharan

1989-01-01

171

On the effects of hydrocarbon and sulphur-containing compounds on the CCN activation of combustion particles  

NASA Astrophysics Data System (ADS)

The European PartEmis project (''Measurement and prediction of emissions of aerosols and gaseous precursors from gas turbine engines'') was focussed on the characterisation and quantification of exhaust emissions from a gas turbine engine. A comprehensive suite of aerosol, gas and chemi-ion measurements were conducted under different combustor operating conditions and fuel sulphur concentrations. Combustion aerosol characterisation included on-line measurements of mass and number concentration, size distribution, mixing state, thermal stability of internally mixed particles, hygroscopicity, cloud condensation nuclei (CCN) activation potential, and off-line analysis of chemical composition. Modelling of CCN activation of combustion particles was conducted using microphysical and chemical properties obtained from the measurements as input data. Based on this unique data set, the role of sulphuric acid coatings on the combustion particles, formed in the cooling exhaust plume through either direct condensation of gaseous sulphuric acid or coagulation with volatile condensation particles nucleating from gaseous sulphuric acid, and the role of the organic fraction for the CCN activation of combustion particles was investigated. It was found that particles containing a large fraction of non-volatile organic compounds grow significantly less at high relative humidity than particles with a lower content of non-volatile OC. Also the effect of the non-volatile OC fraction on the potential CCN activation is significant. While a coating of water-soluble sulphuric acid increases the potential CCN activation, or lowers the activation diameter, respectively, the non-volatile organic compounds, mainly found at lower combustion temperatures, can partially compensate this sulphuric acid-related enhancement of CCN activation of carbonaceous combustion aerosol particles.

Petzold, A.; Gysel, M.; Vancassel, X.; Hitzenberger, R.; Puxbaum, H.; Vrochticky, S.; Weingartner, E.; Baltensperger, U.; Mirabel, P.

2005-05-01

172

Turbulent combustion  

SciTech Connect

Turbulent combustion is the dominant process in heat and power generating systems. Its most significant aspect is to enhance the burning rate and volumetric power density. Turbulent mixing, however, also influences the chemical rates and has a direct effect on the formation of pollutants, flame ignition and extinction. Therefore, research and development of modern combustion systems for power generation, waste incineration and material synthesis must rely on a fundamental understanding of the physical effect of turbulence on combustion to develop theoretical models that can be used as design tools. The overall objective of this program is to investigate, primarily experimentally, the interaction and coupling between turbulence and combustion. These processes are complex and are characterized by scalar and velocity fluctuations with time and length scales spanning several orders of magnitude. They are also influenced by the so-called {open_quotes}field{close_quotes} effects associated with the characteristics of the flow and burner geometries. The authors` approach is to gain a fundamental understanding by investigating idealized laboratory flames. Laboratory flames are amenable to detailed interrogation by laser diagnostics and their flow geometries are chosen to simplify numerical modeling and simulations and to facilitate comparison between experiments and theory.

Talbot, L.; Cheng, R.K. [Lawrence Berkeley Laboratory, CA (United States)

1993-12-01

173

Synthesis of Eu3+ doped yttrium orthosilicate phosphor by sol-combustion method  

NASA Astrophysics Data System (ADS)

Eu3+ doped yttrium orthosilicate (Y2SiO5) phosphor was prepared by the sol-combustion method using citric acid as complexing agent in this experiment. The X-ray diffraction (XRD) pattern, excitation and emission spectra were used to investigate the crystal structure and luminescent properties of the phosphor. XRD pattern showed that pure Y2SiO5:Eu3+ phosphor was obtained. The excitation spectrum was composed of a broad band from 200-350 nm and a series of narrow bands from 350-500 nm, in which the excitation peaks at 400 nm and 470 nm were stronger. The emission spectrum showed the most intense emission peak was located at 613 nm, which corresponded to the 5D0-->7F2 transition of Eu3+. The results showed that this phosphor could be excited by UV or blue light and emit red light. The luminescent intensity depends on the concentration of Eu3+ and it reached the maximum when the molar concentration of Eu3+ was 4 mol%. In this study, we found that the emission intensity reached maximum when the ratio of citric acid and Y3+ was 1.5:1. The results indicated that Y2SiO5:Eu3+ is a potential red-emitting candidate phosphor for white light-emitting diodes.

Guan, Li; Jin, Litao; Jia, Guoqi; Li, Xu; Yang, Zhiping; Guo, Qinglin; Fu, Guangsheng

2010-11-01

174

In vitro immunotoxic and genotoxic activities of particles emitted from two different small-scale wood combustion appliances  

NASA Astrophysics Data System (ADS)

Residential wood combustion appliances emit large quantities of fine particles which are suspected to cause a substantial health burden worldwide. Wood combustion particles contain several potential health-damaging metals and carbon compounds such as polycyclic aromatic hydrocarbons (PAH), which may determine the toxic properties of the emitted particles. The aim of the present study was to characterize in vitro immunotoxicological and chemical properties of PM 1 ( Dp ? 1 ?m) emitted from a pellet boiler and a conventional masonry heater. Mouse RAW264.7 macrophages were exposed for 24 h to different doses of the emission particles. Cytotoxicity, production of the proinflammatory cytokine TNF-? and the chemokine MIP-2, apoptosis and phases of the cell cycle as well as genotoxic activity were measured after the exposure. The type of wood combustion appliance had a significant effect on emissions and chemical composition of the particles. All the studied PM 1 samples induced cytotoxic, genotoxic and inflammatory responses in a dose-dependent manner. The particles emitted from the conventional masonry heater were 3-fold more potent inducers of programmed cell death and DNA damage than those emitted from the pellet boiler. Furthermore, the particulate samples that induced extensive DNA damage contained also large amounts of PAH compounds. Instead, significant differences between the studied appliances were not detected in measurements of inflammatory mediators, although the chemical composition of the combustion particles differed considerably from each other. In conclusion, the present results show that appliances representing different combustion technology have remarkable effects on physicochemical and associated toxicological and properties of wood combustion particles. The present data indicate that the particles emitted from incomplete combustion are toxicologically more potent than those emitted from more complete combustion processes.

Tapanainen, Maija; Jalava, Pasi I.; Mäki-Paakkanen, Jorma; Hakulinen, Pasi; Happo, Mikko S.; Lamberg, Heikki; Ruusunen, Jarno; Tissari, Jarkko; Nuutinen, Kati; Yli-Pirilä, Pasi; Hillamo, Risto; Salonen, Raimo O.; Jokiniemi, Jorma; Hirvonen, Maija-Riitta

2011-12-01

175

The Synthesis and Antimicrobial Activity of Heterocyclic Derivatives of Totarol  

PubMed Central

The synthesis and antimicrobial activity of heterocyclic analogues of the diterpenoid totarol are described. An advanced synthetic intermediate with a ketone on the A-ring is used to attach fused heterocycles, and a carbon-to-nitrogen atom replacement is made on the B-ring by de novo synthesis. A-ring analogues with an indole attached exhibit, for the first time, enhanced antimicrobial activity relative to the parent natural product. Preliminary experiments demonstrate that the indole analogues do not target the bacterial cell division protein FtsZ as had been hypothesized for totarol. PMID:23119123

2012-01-01

176

Structural, morphological and optical investigations on BaMgAl{sub 10}O{sub 17}:Eu{sup 2+} elaborated by a microwave induced solution combustion synthesis  

SciTech Connect

Graphical abstract: Graphical abstract (with Research highlights). This is a paragraph for graphical abstract. Research highlights: {yields} Synthesis of BAM:Eu{sup 2+} by MISCS using different fuel to oxidizer molar ratios. {yields} Both blue and red phosphors were obtained. {yields} Majority of blue phosphors was obtained for fuel-rich synthesis. {yields} A specific morphology was observed for each contribution. -- Abstract: Blue-emitting Eu{sup 2+}-doped barium magnesium aluminate (BaMgAl{sub 10}O{sub 17}:Eu{sup 2+}) for advanced displays and lighting devices was prepared by a microwave induced solution combustion synthesis using urea as combustion fuel and nitrates as oxidizer. Purity control of as-synthesized blue phosphor particles was undertaken by modifying the fuel to oxidizer molar ratio. X-ray diffraction, scanning electron microscopy and photoluminescence were used to investigate powders crystallinity, particles size, morphology and luminescent properties, respectively. Fuel-rich urea reactions preferentially lead to pure phases compared to the powders synthesized with a stoichiometric fuel to oxidizer ratio. In both cases, we produce a nearly pure well-crystallized and nanostructured BaMgAl{sub 10}O{sub 17}:Eu{sup 2+}. Photoluminescence measurements exhibit the characteristic blue emission of Eu{sup 2+} under UV light excitation however a weak red emission associated to Eu{sup 3+} is also detected.

Pradal, Nathalie [Clermont Universite, Laboratoire des Materiaux Inorganiques, BP 10448, F-63000 Clermont-Ferrand (France) [Clermont Universite, Laboratoire des Materiaux Inorganiques, BP 10448, F-63000 Clermont-Ferrand (France); CNRS, UMR 6002, LMI, F-63177 Aubiere (France); Potdevin, Audrey, E-mail: Audrey.Potdevin@univ-bpclermont.fr [Clermont Universite, ENSCCF, Laboratoire des Materiaux Inorganiques, BP 10448, F-63000 Clermont-Ferrand (France) [Clermont Universite, ENSCCF, Laboratoire des Materiaux Inorganiques, BP 10448, F-63000 Clermont-Ferrand (France); CNRS, UMR 6002, LMI, F-63177 Aubiere (France); Chadeyron, Genevieve [Clermont Universite, ENSCCF, Laboratoire des Materiaux Inorganiques, BP 10448, F-63000 Clermont-Ferrand (France) [Clermont Universite, ENSCCF, Laboratoire des Materiaux Inorganiques, BP 10448, F-63000 Clermont-Ferrand (France); CNRS, UMR 6002, LMI, F-63177 Aubiere (France); Mahiou, Rachid [Clermont Universite, Laboratoire des Materiaux Inorganiques, BP 10448, F-63000 Clermont-Ferrand (France) [Clermont Universite, Laboratoire des Materiaux Inorganiques, BP 10448, F-63000 Clermont-Ferrand (France); CNRS, UMR 6002, LMI, F-63177 Aubiere (France)

2011-04-15

177

Advanced bioreactor concepts for gaseous substrates: Conversion of synthesis gas to liquid fuels and removal of SO{sub x} and NO{sub x} from coal combustion gases. CRADA final report  

SciTech Connect

The purpose of the proposed research program was the development and demonstration of a new generation of gaseous substrate-based bioreactors for the production of liquid fuels from coal synthesis gas and the removal of NO{sub x} and SO{sub x} species from coal combustion flue gas. This study addressed the further investigation of optimal bacterial strains, growth media and kinetics for the biocatalytic conversion of coal synthesis gas to liquid fuel such as ethanol and the reduction of gaseous flue gas constituents. The primary emphasis was on the development of advanced bioreactor systems coupled with innovative biocatalytic systems that will provide increased productivity under controlled conditions. It was hoped that this would result in bioprocessing options that have both technical and economic feasibility, thus, ensuring early industrial use. Predictive mathematical models were formulated to accommodate hydrodynamics, mass transport, and conversion kinetics, and provide the data base for design and scale-up. The program was separated into four tasks: (1) Optimization of Biocatalytic Kinetics; (2) Development of Well-mixed and Columnar Reactors; (3) Development of Predictive Mathematical Models; and (4) Industrial Demonstration. Research activities addressing both synthesis gas conversion and flue gas removal were conducted in parallel by BRI and ORNL respectively.

Kaufman, E.N.; Selvaraj, P.T.

1997-10-01

178

Synthesis and anticancer activity studies of cyclopamine derivatives  

Technology Transfer Automated Retrieval System (TEKTRAN)

A diversity-oriented synthesis has been developed for facile construction of a library of carbohydrate-cyclopamine conjugates. The synthetic protocol is suitable for generating cyclopamine derivatives with various structural motifs for exploring the desired activity. From this initial library, we ...

179

Biaryl cannabinoid mimetics--synthesis and structure-activity relationship.  

PubMed

Synthesis, in vitro biological evaluation, and structure-activity relationships of a biaryl cannabinoid mimetic 2 are reported. Variations in the substitution pattern yielded a number of agonists with low nanomolar affinity. Replacing the phenol group by a methyl morpholino acetate group led to compound 28, a 500-fold selective CB(2) receptor agonist. PMID:17507224

Worm, Karin; Zhou, Q Jean; Stabley, Gabriel J; DeHaven, Robert N; Dolle, Roland E

2007-07-01

180

Synthesis of (-)-arctigenin derivatives and their anticancer activity.  

PubMed

The natural dibenzylbutyrolactone type lignanolide (-)-arctigenin, which was prepared from fructus arctii, showed obvious anticancer activity. The synthesis of four new (-)-arctigenin derivatives and their anticancer bioactivities were examined. The structures of the four new synthetic derivatives were elucidated. PMID:21867457

Gui-Rong, Chen; Li-Ping, Cai; De-Qiang, Dou; Ting-Guo, Kang; Hong-Fu, Li; Fu-Rui, Li; Ning, Jiang

2012-01-01

181

Active Combustion Control for Aircraft Gas-Turbine Engines-Experimental Results for an Advanced, Low-Emissions Combustor Prototype  

NASA Technical Reports Server (NTRS)

Lean combustion concepts for aircraft engine combustors are prone to combustion instabilities. Mitigation of instabilities is an enabling technology for these low-emissions combustors. NASA Glenn Research Center s prior activity has demonstrated active control to suppress a high-frequency combustion instability in a combustor rig designed to emulate an actual aircraft engine instability experience with a conventional, rich-front-end combustor. The current effort is developing further understanding of the problem specifically as applied to future lean-burning, very low-emissions combustors. A prototype advanced, low-emissions aircraft engine combustor with a combustion instability has been identified and previous work has characterized the dynamic behavior of that combustor prototype. The combustor exhibits thermoacoustic instabilities that are related to increasing fuel flow and that potentially prevent full-power operation. A simplified, non-linear oscillator model and a more physics-based sectored 1-D dynamic model have been developed to capture the combustor prototype s instability behavior. Utilizing these models, the NASA Adaptive Sliding Phasor Average Control (ASPAC) instability control method has been updated for the low-emissions combustor prototype. Active combustion instability suppression using the ASPAC control method has been demonstrated experimentally with this combustor prototype in a NASA combustion test cell operating at engine pressures, temperatures, and flows. A high-frequency fuel valve was utilized to perturb the combustor fuel flow. Successful instability suppression was shown using a dynamic pressure sensor in the combustor for controller feedback. Instability control was also shown with a pressure feedback sensor in the lower temperature region upstream of the combustor. It was also demonstrated that the controller can prevent the instability from occurring while combustor operation was transitioning from a stable, low-power condition to a normally unstable high-power condition, thus enabling the high-power condition.

DeLaat, John C.; Kopasakis, George; Saus, Joseph R.; Chang, Clarence T.; Wey, Changlie

2012-01-01

182

Synthesis, characterization, temperature dependent electrical and magnetic properties of Ca3Co4O9 by a starch assisted sol-gel combustion method  

NASA Astrophysics Data System (ADS)

In this present work we discussed the synthesis of pure Ca3Co4O9 ceramic powder by a starch assisted sol-gel combustion method. The products were characterized by powder X-ray diffraction (XRD), thermogravimetric and differential thermal analyses (TGA-DTA), Fourier transformation infrared spectroscopy (FTIR), scanning electron microscope (SEM) and UV-visible diffuse reflectance spectroscopy (DRS). X-ray diffraction pattern confirmed the formation of single phase Ca3Co4O9 at a sintering temperature of 1073 K, and it is also confirmed in the thermal analysis. SEM images indicate the presence of diffused microporous sphere like morphology and the grain sizes are in the range of 150-300 nm. Optical properties of Ca3Co4O9 ceramic show a band gap at an energy level of 2.10 eV. A maximum electrical resistivity of 0.002 m? cm was exhibited by Ca3Co4O9 that was decreased to 0.0012 m? cm, when the temperature increased from 300 K to 473 K. Dielectric studies were conducted at various temperatures from room temperature to 673 K and the results indicate that the space charge polarization contributes to the conduction mechanism. It also shows that the dielectric relaxation with activation energy is 0.96 eV. The magnetic properties as a function of temperature represent the ferri-paramagnetic phase transition at above 50 K. M-H curve shows the hysteresis loop with saturation magnetization (Ms) and confirms the presence of soft magnetic materials.

Agilandeswari, K.; Ruban Kumar, A.

2014-09-01

183

EGCG assisted green synthesis of ZnO nanopowders: Photodegradative, antimicrobial and antioxidant activities  

NASA Astrophysics Data System (ADS)

Zinc oxide nanopowders were synthesized by solution combustion method using Epigallocatechin gallate (EGCG) a tea catechin as fuel. The structure and morphology of the product was characterized by Powder X-ray Diffraction, Scanning Electron Microscopy, photoluminescence and UV-Visible spectroscopy. The nanopowders (Nps) were subjected to photocatalytic and biological activities such as antimicrobial and antioxidant studies. PXRD patterns demonstrate that the formed product belongs to hexagonal wurtzite system. SEM images show that the particles are agglomerated to form sponge like structure and the average crystallite sizes were found to be ?10-20 nm. PL spectra exhibit broad and strong peak at 590 nm due to the Zn-vacancies, and O-vacancies. The prepared ZnO Nps exhibit excellent photocatalytic activity for the photodegradation of malachite green (MG) and methylene blue (MB) indicating that the ZnO NPs are potential photocatalytic semiconductor materials. ZnO NPs exhibit significant bactericidal activity against Klebsiella aerogenes, Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus using the agar well diffusion method. Furthermore, the ZnO nano powders show good antioxidant activity by potentially scavenging DPPH radicals. The study successfully demonstrates synthesis of ZnO NPs by simple ecofriendly route employing EGCG as fuel that exhibit superior photodegradative, antibacterial and antioxidant activities.

Suresh, D.; Udayabhanu; Nethravathi, P. C.; Lingaraju, K.; Rajanaika, H.; Sharma, S. C.; Nagabhushana, H.

2015-02-01

184

Practical synthesis of hydroxychromenes and evaluation of their biological activity.  

PubMed

A simple and efficient seven steps synthesis of brodifacoum and difethialone from phenylacetyl chloride is described. The key synthetic strategies involve Friedel-Crafts acylation, intramolecular ring cyclization and condensation reaction in the presence of Brønsted-Lowry acids. It was found that brodifacoum showed favorable inhibiting activities on LPS-stimulated nitrite production in BV-2 microglia cells. Brodifacoum exhibited superior anti-inflammatory effects than difethialone. We expect that an efficient linear synthesis of 4-hydroxycoumarin derivatives and key fragments that are useful agents for the modulation of inflammation as well as inhibition of coagulation will be of practical use. PMID:22205090

Jung, Jae-Chul; Oh, Seikwan

2011-01-01

185

COMBUSTION SYNTHESIS AND CHARACTERIZATION OF NANOCRYSTALLINE ALKALINE EARTH ALUMINATE Sr4Al14O25:RE(RE = Eu, Dy, Sm)  

NASA Astrophysics Data System (ADS)

Nanoscale phosphors have superior performance characteristics than the bulk phosphors. This paper explains the synthesis and characterization like XRD, FTIR, SEM and photoluminescence properties of nanocrystalline Sr4Al14O25 doped with rare earth elements like europium, dysprosium and samarium by combustion method. XRD showed the nanoscale crystalline nature of as-prepared samples. SEM confirmed size of the particle less than 100 nm. Photoluminescent emission spectra showed strong orange red emission at 593 nm for Sr4Al14O25:Sm3+. The green emission of Eu2+ was observed at around 490 nm for Sr4Al14O25:Eu2+.

Hedaoo, V. P.; Bhatkar, V. B.; Omanwar, S. K.

2013-08-01

186

Optimal cooperative control synthesis of active displays  

NASA Technical Reports Server (NTRS)

A technique is developed that is intended to provide a systematic approach to synthesizing display augmentation for optimal manual control in complex, closed-loop tasks. A cooperative control synthesis technique, previously developed to design pilot-optimal control augmentation for the plant, is extended to incorporate the simultaneous design of performance enhancing displays. The technique utilizes an optimal control model of the man in the loop. It is applied to the design of a quickening control law for a display and a simple K/s(2) plant, and then to an F-15 type aircraft in a multi-channel task. Utilizing the closed loop modeling and analysis procedures, the results from the display design algorithm are evaluated and an analytical validation is performed. Experimental validation is recommended for future efforts.

Garg, S.; Schmidt, D. K.

1985-01-01

187

Biological activity of a leached chernozem contaminated with the products of combustion of petroleum gas and its restoration upon phytoremediation  

NASA Astrophysics Data System (ADS)

It is shown that contamination of leached chernozems by combustion products of petroleum gas favors changes in the biological activity of the soil: the number of hydrocarbon-oxidizing bacteria and micromycetes has increased, as well as the activity of catalase and lipase and phytotoxicity. Bromopsis inermis Leys used as a phytoameliorant has accelerated the destruction of hydrocarbons in the rhizosphere. The benzpyrene concentration in plants on contaminated soils considerably exceeds its background concentration.

Kireeva, N. A.; Novoselova, E. I.; Shamaeva, A. A.; Grigoriadi, A. S.

2009-04-01

188

Synthesis, characterization of double perovskite Ca{sub 2}MSbO{sub 6} (M = Dy, Fe, Cr, Al) materials via sol–gel auto-combustion and their catalytic properties  

SciTech Connect

Double perovskite-type oxide Ca{sub 2}MSbO{sub 6} materials, where M = Dy, Fe, Cr, and Al, were prepared by using the sol–gel auto-combustion method. The role of different B-site cations on their synthesis, structures, morphologies and catalytic properties was investigated. The progress of double-perovskite type structure formation and the disappearance of the organic phases were monitored by infrared absorption spectroscopy (FTIR). Double perovskite oxide structures were evaluated using X-ray diffraction (XRD), while the microstructure of obtained compounds was studied using scanning electron microscopy (SEM). Also, BET surface areas were measured at the liquid nitrogen temperature by nitrogen adsorption. Catalytic properties of the obtained compounds were evaluated by test reaction of hydrogen peroxide decomposition. - Highlights: • Ca{sub 2}MSbO{sub 6} double perovskites were obtained by sol–gel auto-combustion method. • Ca{sub 2}MSbO{sub 6} (M = Dy, Fe, Cr and Al) as catalysts in H{sub 2}O{sub 2} decomposition • Strong relationship between particles' shape, BET area and catalytic performance • Ca{sub 2}FeSbO{sub 6} spherical grains show superior catalytic activity.

Feraru, S. [“Alexandru Ioan Cuza” University, Faculty of Chemistry, Bv. Carol I no. 11, Iasi 700506 (Romania); Samoila, P. [“Petru Poni” Institute of Macromolecular Chemistry, 41A, Gr. Ghica Voda Alley, 700487 Iasi (Romania); Borhan, A.I. [“Alexandru Ioan Cuza” University, Faculty of Chemistry, Bv. Carol I no. 11, Iasi 700506 (Romania); Ignat, M. [“Alexandru Ioan Cuza” University, Faculty of Chemistry, Bv. Carol I no. 11, Iasi 700506 (Romania); “Petru Poni” Institute of Macromolecular Chemistry, 41A, Gr. Ghica Voda Alley, 700487 Iasi (Romania); Iordan, A.R. [“Alexandru Ioan Cuza” University, Faculty of Chemistry, Bv. Carol I no. 11, Iasi 700506 (Romania); Palamaru, M.N., E-mail: palamaru@uaic.ro [“Alexandru Ioan Cuza” University, Faculty of Chemistry, Bv. Carol I no. 11, Iasi 700506 (Romania)

2013-10-15

189

Synthesis, structural investigation and magnetic properties of Zn2+ substituted cobalt ferrite nanoparticles prepared by the sol-gel auto-combustion technique  

NASA Astrophysics Data System (ADS)

Structural morphology and magnetic properties of the Co1-xZnxFe2O4 (0.0?x?1.0) spinel ferrite system synthesized by the sol-gel auto-combustion technique using nitrates of respective metal ions have been studied. The ratio of metal nitrates to citric acid was taken at 1:3. The as prepared powder of cobalt zinc ferrite was sintered at 600 °C for 12 h after TG/DTA thermal studies. Compositional stoichiometry was confirmed by energy dispersive analysis of the X-ray (EDAX) technique. Single phase cubic spinel structure of Co-Zn nanoparticles was confirmed by XRD data. The average crystallite size (t), lattice constant (a) and other structural parameters of zinc substituted cobalt ferrite nanoparticles were calculated from XRD followed by SEM and FTIR. It is observed that the sol-gel auto-combustion technique has many advantages for the synthesis of technologically applicable Co-Zn ferrite nanoparticles. The present investigation clearly shows the effect of the synthesis method and possible relation between magnetic properties and microstructure of the prepared samples. Increase in nonmagnetic Zn2+ content in cobalt ferrite nanoparticles is followed by decrease in nB, Ms and other magnetic parameters. Squareness ratio for the Co-ferrite was 1.096 at room temperature.

Raut, A. V.; Barkule, R. S.; Shengule, D. R.; Jadhav, K. M.

2014-05-01

190

Synthesis and anticholinesterase activity of new bispyridinium compounds.  

PubMed

Synthesis of new bis(1-methylpyridinium) compounds containing a 1,4-diacetylbenzene linkage between the pyridinium moieties from commercially available 2-, 3-, and 4-picoline precursors was accomplished via metallation, reaction of the picolyllithium with 1,4-dicyanobenzene, and subsequent quaternization of the resulting bispyridyl compounds. Acetylcholinesterase inhibitory activity was determined colorimetrically with purified electric eel enzyme. Examination of structure-activity relationships indicated that the 3-substituted pyridinium compound is the most potent isomer, followed by the 2-substituted isomer, and that the 4-substituted analogue is the least active. PMID:1491336

Hsu, F L; Ray, R; Clark, O E; Munavalli, S; Ashman, W P

1992-12-01

191

Synthesis and antimalarial activity of prodigiosenes.  

PubMed

Several analogues of the natural compound prodigiosin with modified A- and C-rings were synthesised as were some of their tin, cobalt, boron and zinc complexes. The antimalarial activity of these prodigiosenes was evaluated in vitro using the 3D7 Plasmodium falciparum strain. The presence of a nitrogen atom in the A-ring is needed for antimalarial activity but the presence of an alkyl group at the ?'-position of the C-ring seems detrimental. Dibutyl tin complexes exhibit IC50 values mostly in the nanomolar range with equal or improved activity compared to the free-base prodigiosene ligand, despite the fact that the general toxicity of such tin complexes is demonstrably lower than that of the free-bases. PMID:24834447

Marchal, Estelle; Smithen, Deborah A; Uddin, Md Imam; Robertson, Andrew W; Jakeman, David L; Mollard, Vanessa; Goodman, Christopher D; MacDougall, Kristopher S; McFarland, Sherri A; McFadden, Geoffrey I; Thompson, Alison

2014-06-28

192

Self-propagating combustion synthesis of CdSiO3 nano powder: structural and dosimetric applications  

NASA Astrophysics Data System (ADS)

Un-doped CdSiO3 nano phosphor has been synthesized by a low temperature solution combustion technique using cadmium nitrate as a cadmium source, oxalyldihydrazide (ODH) as a fuel and tetraethyl orthosilicate (TEOS) as a silica source. Powder x-ray diffraction (PXRD) patterns of CdSiO3 sample calcined at 800 °C for 2 h show monoclinic phase. The average crystallite sizes were estimated using Debye–Scherrer’s formula and Williamson–Hall (W–H) plots and are found to be 23–32 nm, respectively. SEM and TEM images of CdSiO3 reveal that they are foamy products with large agglomerates of very fine particles and the particles are in nano size. The optical energy band gap (Eg) of un-doped sample was estimated from Tauc relation as 5.6 eV. Thermoluminescence (TL) spectrum of the samples irradiated with UV source in the dose range 5–40 min was recorded at a heating rate of 5 °C s?1. The phosphor shows a well resolved glow peak at ?166 °C. It is observed that TL intensity increased almost linearly with increase of dose, which is highly useful in radiation dosimetry. The kinetic parameters such as activation energy (E), frequency factor (s) and order of kinetics was estimated by three different methods.

Manohara, B. M.; Nagabhushana, H.; Thyagarajan, K.; Prashantha, S. C.; Nagabhushana, B. M.; Shivakumara, C.; Sharma, S. C.

2015-02-01

193

Synthesis and antiproliferative activity of 6-phenylaminopurines.  

PubMed

A series of novel 6-phenylaminopurines have been efficiently synthesized in 3 steps exploring different groups at positions 2, 8 and 9 of the purine ring and at the exocyclic nitrogen atom at position 6. Among the newly described purines, five compounds showed antiproliferative activity with IC50 values below 10 ?M, the tetrahydroquinoline derivative at position 6 of phenylaminopurine being the most active of the series in the six cell lines tested. Moreover, the compounds induced G2/M phase arrest in human cervical carcinoma HeLa cells as reported for tubulin depolymerizing agents. PMID:25282265

Canela, María-Dolores; Liekens, Sandra; Camarasa, María-José; Priego, Eva María; Pérez-Pérez, María-Jesús

2014-11-24

194

Synthesis and pharmacological activity of diterpenylnaphthoquinone derivatives.  

PubMed

New diterpenylquinones, combining a diterpene diacid and a naphthoquinone, were prepared from junicedric acid and lapachol. The new derivatives were assessed as gastroprotective agents by the HCl-EtOH-induced gastric lesions model in mice as well as for basal cytotoxicity on the following human cell lines: Normal lung fibroblasts (MRC-5), gastric epithelial adenocarcinoma (AGS), and hepatocellular carcinoma (Hep G2). Several of the new compounds were significantly active as antiulcer agents and showed selective cytotoxicity against AGS cells. PMID:21996716

Pertino, Mariano Walter; Theoduloz, Cristina; Palenzuela, Jose Antonio; Afonso, Maria del Mar; Yesilada, Erdem; Monsalve, Francisco; González, Paulo; Droguett, Daniel; Schmeda-Hirschmann, Guillermo

2011-01-01

195

Effect of inhibitors of protein synthesis and DNA replication on the induction of proteolytic activities, caspase-like activities and  

E-print Network

Effect of inhibitors of protein synthesis and DNA replication on the induction of proteolytic about this process remain, two of which are whether it requires protein synthesis and whether of proteolytic activities and the cell death event, we used inhibitors of cytoplasmic protein synthesis

Berges, John A.

196

Enhanced silver nanoparticle synthesis by optimization of nitrate reductase activity.  

PubMed

Nanostructure materials are attracting a great deal of attention because of their potential for achieving specific processes and selectivity, especially in biological and pharmaceutical applications. The generation of silver nanoparticles using optimized nitrate reductase for the reduction of Ag(+) with the retention of enzymatic activity in the complex is being reported. This report involves the optimization of enzyme activity to bring about enhanced nanoparticle synthesis. Response surface methodology and central composite rotary design (CCRD) were employed to optimize a fermentation medium for the production of nitrate reductase by Bacillus licheniformis at pH 8. The four variables involved in the study of nitrate reductase were Glucose, Peptone, Yeast extract and KNO(3). Glucose had a significant effect on nitrate reductase production. The optimized medium containing (%) Glucose: 1.5, Peptone: 1, Yeast extract: 0.35 and KNO(3): 0.35 resulted in a nitrate reductase activity of 452.206 U/ml which is same as that of the central level. The medium A (showing least nitrate reductase activity) and the medium B (showing maximum nitrate reductase activity) were compared for the synthesis. Spectrophotometric analysis revealed that the particles exhibited a peak at 431 nm and the A(431) for the medium B was 2-fold greater than that of the medium A. The particles were also characterized using TEM. The particles synthesized using the optimized enzyme activity ranged from 10 to 80 nm and therefore can be extended to various medicinal applications. PMID:19796922

Vaidyanathan, Ramanathan; Gopalram, Shubaash; Kalishwaralal, Kalimuthu; Deepak, Venkataraman; Pandian, Sureshbabu Ram Kumar; Gurunathan, Sangiliyandi

2010-01-01

197

Synthesis and antitumor activity of feruloyl and caffeoyl derivatives.  

PubMed

We developed two efficient protocols for the synthesis of feruloyl and caffeoyl derivatives from commercial vanillin and veratraldehyde. Pharmacological activities were assessed against a panel of human cancer cell lines in vitro. Most synthesized compounds demonstrated attractive cytotoxicity. Several new compounds demonstrated significant antiproliferative and cytotoxic activities against HeLa and Bewo tumor cell lines. In particular, 5-nitro caffeic adamantyl ester showed broad spectrum of tumor inhibition in 10 cell lines, and reduced tumor weight by 36.7% in vivo when administered at a dose of 40 mg kg(-1). PMID:25160837

Chen, Hui-zhen; Chen, You-bao; Lv, Ya-ping; Zeng, Fang; Zhang, Juan; Zhou, Yong-lie; Li, Han-bing; Chen, Li-fei; Zhou, Bin-jie; Gao, Jian-rong; Xia, Chun-nian

2014-09-15

198

Synthesis and characterization of activated carbo-aluminosilicate material from oil shale  

E-print Network

Synthesis and characterization of activated carbo-aluminosilicate material from oil shale Reyad activated carbo-aluminosilicate materials were prepared from oil shale by chemical activation. The chemical Published by Elsevier Inc. Keywords: Synthesis; Activated carbo-aluminosilicate; Adsorption; Oil shale

Shawabkeh, Reyad A.

199

Synthesis and characterization of photochemically active amphiphiles  

SciTech Connect

A novel class of photochemically active amphiphiles has been synthesized containing a ketone moiety as a biradical or radical pair precursor on linear and cyclic hydrophobic tails of mono- and his alkyl sulfate surfactants. Photolysis of aqueous solutions of these surfactants allows for the generation of radical pairs and biradicals within the micelle. Time-resolved electron paramagnetic resonance (TREPR) spectroscopy has been used to study the internal properties of the micelles and the effects the micellar environment has on the electronic coupling. Alteration of the molecular structure of each ketone-containing surfactant allows for the systematic and predictable manipulation of the micellar size and shape, both of which are important in determining the coupling between the unpaired electrons. The structure of the micelles has been analyzed by small angle neutron scattering (SANS).

Schulz, G.R.; Martino, D.C.; Triolo, R. [Univ. of North Carolina, Chapel Hill, NC (United States)] [and others

1996-10-01

200

Synthesis and Anticancer Activity of all known (?)-Agelastatin Alkaloids  

PubMed Central

The full details for our enantioselective total syntheses of (?)-agelastatins A–F (1–6), the evolution of a new methodology for synthesis of substituted azaheterocycles, and the first side-by-side evaluation of all known (?)-agelastatin alkaloids against nine human cancer cell lines are described. Our concise synthesis of these alkaloids exploits the intrinsic chemistry of plausible biosynthetic precursors and capitalizes on a late-stage synthesis of the C-ring. The critical copper-mediated cross-coupling reaction was expanded to include guanidine-based systems, offering a versatile preparation of substituted imidazoles. The direct comparison of the anticancer activity of all naturally occurring (?)-agelastatins in addition to eight advanced synthetic intermediates enabled a systematic analysis of the structure activity relationship within the natural series. Significantly, (?)-agelastatin A (1) is highly potent against six blood cancer cell lines (20–190 nM) without affecting normal red blood cells (>333 ?M). (?)-Agelastatin A (1) and (?)-agelastatin D (4), the two most potent members of this family, induce dose dependent apoptosis and arrest cells in the G2/M-phase of the cell cycle; however, using confocal microscopy we have determined that neither alkaloid affects tubulin dynamics within cells. PMID:24152243

Han, Sunkyu; Siegel, Dustin S.; Morrison, Karen C.; Hergenrother, Paul J.

2014-01-01

201

The effect of gravity on the combustion synthesis of Ni-Al and Ni3Al-TiB2 composites from elements  

NASA Technical Reports Server (NTRS)

Previous studies on the combustion synthesis of advanced materials indicate that combustion and structure formation mechanisms involve several stages including melting of reactants and products, spreading of the melt, droplet coalescence, diffusion and convection, buoyancy of solid particles, and densification of the liquid product. Most of these processes are affected by gravity. Conducting the combustion synthesis under microgravity conditions is expected to help elucidate the reaction mechanisms. Two systems were examined. The first involves Ni/AI cladded particles, which is an ideal system to examine the individual particle and liquid flow before combustion occurs. For comparison, elemental Ni and Al powders with the same stoichiometry as that of the cladded particles were also used in some experiments. The second system was the Ni3AITiB2 composite in which the Ni3AI (-delta H(sub f) = 153.1 kJ/mol) phase melts during reaction enabling us to examine settling of the liquid phase. The amount of liquid phase was controlled by varying the TiB2 (-delta H(sub f) = 323.8 kJ/mol) content which generates the additional heat. The overall reactions for the two systems can be expressed as follows. System 1: 4Ni + 2AI yields Ni3AI + NiA and System 2: 3Ni + Al + x (Ti + 2B) yields Ni3Al + x(TiB2). For the first system, pellets were pressed directly from the cladded particles, at green densities about 77 +/- 3% of theoretical value. For the second, the pellets were prepared by mixing the elemental reactant powders in the required stoichiometry by ball-milling and then pressing uniaxially at green densities about 70 +/- 3 percent of theoretical. The pellets were cylindrical in shape, 10 mm in diameter and length typically 20-30 mm. The pellet samples were reacted in UHP Argon (1 atm) using the experimental setup and procedure described previously. After reaction, the samples were sectioned axially in order to conduct the microstructural analysis in the longitudinal direction. The phase composition of the reacted product was determined by X-ray diffraction (XRD) and the microstructure was analyzed using scanning electron microscopy (SEM) along with energy dispersive X-ray spectrometry (EDX).

Varma, Arvind; Yi, Hu Chun; Mcginn, Paul J.

1995-01-01

202

Feasibility of manufacturing geopolymer bricks using circulating fluidized bed combustion bottom ash  

Microsoft Academic Search

This paper presents a study on geopolymer bricks manufactured using bottom ash from circulating fluidized bed combustion (CFBC). The alkali activators used for synthesis were sodium silicate, sodium hydroxide, and potassium hydroxide and lithium hydroxide solutions. The study included the impact of alkali activator on compressive strength. The reaction products were analysed by XRD, FT-IR and SEM\\/EDS. The compressive strength

Chen Chen; Qin Li; Lifeng Shen; Jianping Zhai

2012-01-01

203

Feasibility of manufacturing geopolymer bricks using circulating fluidized bed combustion bottom ash  

Microsoft Academic Search

This paper presents a study on geopolymer bricks manufactured using bottom ash from circulating fluidized bed combustion (CFBC). The alkali activators used for synthesis were sodium silicate, sodium hydroxide, and potassium hydroxide and lithium hydroxide solutions. The study included the impact of alkali activator on compressive strength. The reaction products were analysed by XRD, FT-IR and SEM\\/EDS. The compressive strength

Chen Chen; Qin Li; Lifeng Shen; Jianping Zhai

2011-01-01

204

Original article Nature of brood signal activating the protein synthesis of  

E-print Network

Original article Nature of brood signal activating the protein synthesis of hypopharyngeal gland the protein synthesis of hypopharyngeal glands of nurse honey bees. An in vitro bioassay, modified from Brouwers (1982), was used to measure protein synthesis in glands from bees reared under dif- ferent

Paris-Sud XI, Université de

205

Test plan for measuring ventilation rates and combustible gas levels in TWRS active catch tanks  

SciTech Connect

The purpose of this test is to provide an initial screening of combustible gas concentrations in catch tanks that currently are operated by Tank Waste Remediation System (TWRS). The data will be used to determine whether or not additional data will be needed for closure of the flammable gas unreviewed safety question for these facilities. This test will involve field measurements of ammonia, organic vapor, and total combustible gas levels in the headspace of the catch tanks. If combustible gas level in a tank exceeds an established threshold, gas samples will be collected in SUMMA canisters for more extensive laboratory analysis. In addition, ventilation rates of some catch tanks will be measured to evaluate removal of flammable gas by air flow through the tanks.

NGUYEN, D.M.

1999-05-20

206

Test plan for measuring ventilation rates and combustible gas levels in RPP active catch tanks  

SciTech Connect

The purpose of this test is to provide an initial screening of combustible gas concentrations in catch tanks that currently are operated by River Protection Project (RPP). The data will be used to determine whether or not additional data will be needed for closure of the flammable gas unreviewed safety question for these facilities. This test will involve field measurements of ammonia, organic vapor, and total combustible gas levels in the headspace of the catch tanks. If combustible gas level in a tank exceeds an established threshold, gas samples will be collected in SUMMA canisters for more extensive laboratory analysis. In addition, ventilation rates of some catch tanks will be measured to evaluate removal of flammable gas by air flow through the tanks.

NGUYEN, D.M.

1999-06-03

207

Synthesis and biological activity of fluorescent neonicotinoid insecticide thiamethoxam.  

PubMed

Here, we describe the synthesis of two new fluorescent derivatives of thiamethoxam and compared their toxicity on aphid Acyrthosiphon pisum and their mode of action on insect nicotinic acetylcholine receptors expressed on the sixth abdominal ganglion. The compound 3 with two 2-chlorothiazole moieties was found to be more toxic using toxicological bioassays 24 h and 48 h after exposure while compound 4 appeared more active using cockroach ganglionic depolarization. Interestingly, thiamethoxam appeared more effective than component 3 and 4, respectively. Our results demonstrated that component 3 and 4 act as agonists of insect nicotinic acetylcholine receptors. PMID:24915877

Taillebois, Emiliane; Langlois, Paul; Cunha, Thomas; Seraphin, Denis; Thany, Steeve H

2014-08-01

208

Synthesis, characterization and antiproliferative activity of ?-aryl-?-iodo-?-lactones  

NASA Astrophysics Data System (ADS)

A convenient pathway for the synthesis of new of ?-aryl-?-iodo-?-lactones is described. The synthetic route led to both cis and trans isomers which were separated by column chromatography or crystallization. The structures of synthesized compounds were confirmed by spectroscopic methods: IR, NMR and HR-MS. For lactones with naphthyl ring (6e and 7e) the crystal structures were also obtained. The lactones were screened for biological evaluation against cancer line HL-60 (human promyelocytic leukemia). The tests showed that the presence of substituent at the benzene ring does not significantly affect the antiproliferative activity of the compound.

Wzorek, Alicja; Gawdzik, Barbara; G?adkowski, Witold; Urbaniak, Mariusz; Bara?ska, Anita; Mali?ska, Maura; Wo?niak, Krzysztof; Kempi?ska, Katarzyna; Wietrzyk, Joanna

2013-09-01

209

Synthesis of a FTO inhibitor with anticonvulsant activity.  

PubMed

We describe the rationale for and the synthesis of a new class of compounds utilizing a modular approach that are designed to mimic ascorbic acid and to inhibit 2-oxoglutarate-dependent hydroxylases. Preliminary characterization of one of these compounds indicates in vivo anticonvulsant activity (6 Hz mouse model) at nontoxic doses, inhibition of the 2-oxoglutarate-dependent hydroxylase FTO, and expected increase in cellular N(6)-methyladenosine. This compound is also able to modulate various microRNA, an interesting result in light of the recent view that modulation of microRNAs may be useful for the treatment of CNS disease. PMID:24834807

Zheng, Guanqun; Cox, Thomas; Tribbey, Leah; Wang, Gloria Z; Iacoban, Paulina; Booher, Matthew E; Gabriel, Gregory J; Zhou, Lu; Bae, Nancy; Rowles, Joie; He, Chuan; Olsen, Mark J

2014-08-20

210

Efficient discovery of bioactive scaffolds by activity-directed synthesis  

NASA Astrophysics Data System (ADS)

The structures and biological activities of natural products have often provided inspiration in drug discovery. The functional benefits of natural products to the host organism steers the evolution of their biosynthetic pathways. Here, we describe a discovery approach—which we term activity-directed synthesis—in which reactions with alternative outcomes are steered towards functional products. Arrays of catalysed reactions of ?-diazo amides, whose outcome was critically dependent on the specific conditions used, were performed. The products were assayed at increasingly low concentration, with the results informing the design of a subsequent reaction array. Finally, promising reactions were scaled up and, after purification, submicromolar ligands based on two scaffolds with no previous annotated activity against the androgen receptor were discovered. The approach enables the discovery, in tandem, of both bioactive small molecules and associated synthetic routes, analogous to the evolution of biosynthetic pathways to yield natural products.

Karageorgis, George; Warriner, Stuart; Nelson, Adam

2014-10-01

211

Efficient discovery of bioactive scaffolds by activity-directed synthesis.  

PubMed

The structures and biological activities of natural products have often provided inspiration in drug discovery. The functional benefits of natural products to the host organism steers the evolution of their biosynthetic pathways. Here, we describe a discovery approach--which we term activity-directed synthesis--in which reactions with alternative outcomes are steered towards functional products. Arrays of catalysed reactions of ?-diazo amides, whose outcome was critically dependent on the specific conditions used, were performed. The products were assayed at increasingly low concentration, with the results informing the design of a subsequent reaction array. Finally, promising reactions were scaled up and, after purification, submicromolar ligands based on two scaffolds with no previous annotated activity against the androgen receptor were discovered. The approach enables the discovery, in tandem, of both bioactive small molecules and associated synthetic routes, analogous to the evolution of biosynthetic pathways to yield natural products. PMID:25242481

Karageorgis, George; Warriner, Stuart; Nelson, Adam

2014-10-01

212

Energy efficiency analyses of active flow aftertreatment systems for lean burn internal combustion engines  

Microsoft Academic Search

The use of three way catalytic converters in stoichiometric burn reciprocating internal combustion engine systems has proved to be an effective and efficient method for reducing the level of criteria pollutants. However, such passive systems have not been as successful in emission amelioration when combined with lean burn engines. This is because of the thermochemical nature of the exhaust gases

Ming Zheng; Graham T. Reader

2004-01-01

213

A status of the activities of the NASA. Marshall Space Flight Center Combustion Devices Technology Team  

NASA Technical Reports Server (NTRS)

The Consortium for Computational Fluid Dynamics (CFD) Applications in Propulsion Technology was established to focus on computational fluid dynamics applications in propulsion. Specific areas of effort include developing the CFD technology required to address rocket propulsion issues, validating the technology, and applying the validated technology to design problems. The Combustion Devices Technology Team was formed to implement the above objectives in the broad area of combustion driven flows. In an effort to bring CFD to bear in the design environment, the team has focused its efforts on the Space Transportation Main Engine nozzle. The main emphasis has been on the film cooling scheme used to cool the nozzle wall. Benchmark problems have been chosen to validate CFD film cooling capabilities. CFD simulations of the subscale nozzle have been made. Also, CFD predictions of the base flow resulting from this type of nozzle have been made. The status of these calculations is presented along with future plans. Information is given in viewgraph form.

Tucker, Kevin

1992-01-01

214

Synthesis of Cu/CNTs nanocomposites for antimicrobial activity  

NASA Astrophysics Data System (ADS)

We report a facile method for the synthesis of Cu/multi-walled carbon nanotubes (CNTs) composite powder employing a chemical reduction method followed by high-energy ball milling involving the use of sodium borohydride as a reducing agent and copper sulphate as the precursor material. Control of oxidation of Cu nanoparticles (CuNPs) is a key factor in the synthesis of Cu/CNTs nanocomposites via chemical reduction methods and other methods. To overcome this problem we have applied a new facile rapid synthesis method using a combination of molecular-level mixing followed by high-energy ball milling to produce mostly CuNPs. X-ray diffraction results indicated the presence of mostly CuNPs in composite powder. Scanning electron microscopy and high resolution transmission electron microscopy (HRTEM) was used to ascertain the dispersion of CNTs in Cu matrix. Most of the CuNPs synthesized in the present work had a particle size ranging from 20–50 nm as revealed by HRTEM characterization. Moreover, the CNTs were also found to be homogeneously dispersed in Cu matrix. The Cu/CNTs nanocomposite has a wide range of applications from fuel cells to electronic chip components. In the present work we have investigated the antimicrobial activity of Cu powder and varying concentrations of Cu/CNTs nanocomposite against gram negative Providencia sp. bacteria, and gram positive Bacillus sp. bacteria. These findings suggest that Cu/CNTs nanocomposite can be used in antibacterial controlling systems and as an effective growth inhibitor in the case of various microorganisms.

Singhal, Sunil Kumar; Lal, Maneet; Lata; Ranjan Kabi, Soumya; Behari Mathur, Rakesh

2012-12-01

215

Coal Combustion Science  

SciTech Connect

The objective of this activity is to support the Office of Fossil Energy in executing research on coal combustion science. This activity consists of basic research on coal combustion that supports both the Pittsburgh Energy Technology Center Direct Utilization Advanced Research and Technology Development Program, and the International Energy Agency Coal Combustion Science Project. Specific tasks for this activity include: (1) coal devolatilization - the objective of this risk is to characterize the physical and chemical processes that constitute the early devolatilization phase of coal combustion as a function of coal type, heating rate, particle size and temperature, and gas phase temperature and oxidizer concentration; (2) coal char combustion -the objective of this task is to characterize the physical and chemical processes involved during coal char combustion as a function of coal type, particle size and temperature, and gas phase temperature and oxygen concentration; (3) fate of mineral matter during coal combustion - the objective of this task is to establish a quantitative understanding of the mechanisms and rates of transformation, fragmentation, and deposition of mineral matter in coal combustion environments as a function of coal type, particle size and temperature, the initial forms and distribution of mineral species in the unreacted coal, and the local gas temperature and composition.

Hardesty, D.R. (ed.); Fletcher, T.H.; Hurt, R.H.; Baxter, L.L. (Sandia National Labs., Livermore, CA (United States))

1991-08-01

216

Thermoelectric and magnetic properties of perovskite-type manganate phases synthesised by ultrasonic spray combustion (USC)  

Microsoft Academic Search

Electron-doped manganate phases were synthesised by ultrasonic spray combustion (USC) to investigate the magnetic and transport properties related to their morphology. The nanocrystallite microstructure obtained from the USC synthesis is characterized by the presence of twinned domains coexisting with ordered crystalline material. Classical solid state reaction (SSR) methods were applied to compare their thermoelectric activities with the USC compounds. Magnetic

Laura Bocher; Rosa Robert; Myriam H. Aguirre; Sylvie Malo; Sylvie Hébert; Antoine Maignan; Anke Weidenkaff

2008-01-01

217

Synthesis and Structural Activity Relationship Study of Antitubercular Carboxamides  

PubMed Central

The unusual structure and chemical composition of the mycobacterial cell wall, the tedious duration of therapy, and resistance developed by the microorganism have made the recurrence of the disease multidrug resistance and extensive or extreme drug resistance. The prevalence of tuberculosis in synergy with HIV/AIDS epidemic augments the risk of developing the disease by 100-fold. The need to synthesize new drugs that will shorten the total duration of effective treatment and/or significantly reduce the dosage taken under DOTS supervision, improve on the treatment of multidrug-resistant tuberculosis which defies the treatment with isoniazid and rifampicin, and provide effective treatment for latent TB infections which is essential for eliminating tuberculosis prompted this review. In this review, we considered the synthesis and structure activity relationship study of carboxamide derivatives with antitubercular potential. PMID:25610646

Ugwu, D. I.; Ezema, B. E.; Eze, F. U.; Ugwuja, D. I.

2014-01-01

218

Nordihydroguaiaretic acid analogues: their chemical synthesis and biological activities.  

PubMed

Nordihydroguaiaretic acid is a natural occurring lignan mainly isolated and commercially produced from desert plant, creosote bush (Larrea divaricata Cav. Or Corillea tridentate), which can be widely found in the border zone of southern of USA and northern of Mexico. During past 100 years, extensive research has demonstrated that nordihydroguaiaretic acid and its synthetic analogues are potentially useful in treating diseases related to cancers, diabetes, viral, bacterial infections, and inflammation. Remarkably, terameprocol, a tetra-O-methyl derivative of nordihydroguaiaretic acid, is currently in Phase I/II clinical trials as an anticancer agent. This review deals with the chemical synthesis and bioactivities of nordihydroguaiaretic acid and its structurally-related derivatives, which possess anticancer, antioxidant, antimicrobial, anti-inflammatory and immunosuppressive activities. The review consists of the data reported in over 100 publications. PMID:19903157

Chen, Qingqi

2009-01-01

219

Optical properties and dye-sensitized solar cell applications of ZnO nanostructures prepared by microwave combustion synthesis.  

PubMed

In the present study, ZnO nanoparticles (ZNPs) and nanoflakes (ZNFs) were prepared by conventional combustion method and microwave combustion method, respectively. The structural phase and morphology were investigated by using X-ray diffraction (XRD), high resolution scanning electron microscopy (HR-SEM) and high resolution transmission electron microscopy (HR-TEM). The crystallite size was calculated using Scherrer formula, and it lies in the range of 20-21 nm for ZNFs and 23-28 nm for ZNPs. The elemental analysis was investigated by energy dispersive X-ray analysis (EDX). Also, absorbance and emission spectra were measured by using diffuse reflectance (DRS) and photoluminescence (PL) studies. The band gap was measured using Kubelka-Munk model and it shows 3.47 eV for ZNFs and 3.26 eV for ZNPs. A fill factor (FF) of 0.57, short-circuit current (J(sc)) of 8.02 mA/cm2, open-circuit voltage (V(oc)) of 0.70 V and an overall light to electricity conversion efficiency (eta) of 1.62% were obtained from the dye-sensitized solar cell (DSSCs) based on ZNFs. PMID:24745267

Manikandan, A; Vijaya, J Judith; Ragupathi, C; Kennedy, L John

2014-03-01

220

Synthesis of Li2TiO3 by sol-gel combustion method and its gel-casting formation  

NASA Astrophysics Data System (ADS)

Lithium metatitanate (Li2TiO3) has been recognized as a candidate of ceramic tritium breeder materials for its excellent performance. In this paper, Li2TiO3 powder was synthetized by a modified sol-gel combustion process, and the ratio of fuel to oxidizer was optimized. DTA-TG analysis indicated that an intense exothermic reaction occurred at 539 K, which led to the formation of a voluminous white powder. No additional annealing process was required, as pure crystalline ?-Li2TiO3 was directly obtained from the combustion reaction. The powder had nano-scale structure and large specific surface area of 9.6 m2/g. Li2TiO3 pebbles with desired size and shape were prepared by gel-casting technique using the as-prepared powder. The pebbles reached a high density (81-86% T.D) after sintered at a relatively low temperature (?1373 K) for 2 h. The sintering pebbles had a smooth surface, homogeneous microstructure and small grain size.

Hong, Ming; Zhang, Yingchun; Mi, Yingying; Jiang, Yuanyuan; Xiang, Maoqiao

2014-12-01

221

Synthesis, characterization and photoluminescence properties of Gd 2O 3:Eu 3+ nanophosphors prepared by solution combustion method  

NASA Astrophysics Data System (ADS)

Gd 2O 3:Eu 3+ (0.5-8.0 mol%) nanophosphors have been prepared by low temperature solution combustion method using metal nitrates as oxidizers and oxalyl dihydrazide (ODH) as a fuel. The phosphors are well characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and photoluminescence (PL) techniques. PXRD patterns of as-formed and calcined (800 °C, 3 h) Gd 2O 3 powders exhibit monoclinic phase with mean crystallite sizes ranging from 20 to 50 nm. Eu 3+ doping changes the structure from monoclinic to mixed phase of monoclinic and cubic. SEM micrographs shows the products are foamy, agglomerated and fluffy in nature due to the large amount of gases liberated during combustion reaction. Upon 254 nm excitation the photoluminescence of the Gd 2O 3:Eu 3+ particles show red emission at 611 nm corresponding to 5D 0? 7F 2 transition. It is observed that PL intensity increases with calcination temperature. This might be attributed to better crystallization and eliminates the defects, which serve as centers of non-radiative relaxation for nanomaterials. It is observed that the optical energy gap ( Eg) is widened with increase Eu 3+ content.

Dhananjaya, N.; Nagabhushana, H.; Nagabhushana, B. M.; Chakradhar, R. P. S.; Shivakumara, C.; Rudraswamy, B.

2010-09-01

222

Third millenium ideal gas and condensed phase thermochemical database for combustion (with update from active thermochemical tables).  

SciTech Connect

The thermochemical database of species involved in combustion processes is and has been available for free use for over 25 years. It was first published in print in 1984, approximately 8 years after it was first assembled, and contained 215 species at the time. This is the 7th printed edition and most likely will be the last one in print in the present format, which involves substantial manual labor. The database currently contains more than 1300 species, specifically organic molecules and radicals, but also inorganic species connected to combustion and air pollution. Since 1991 this database is freely available on the internet, at the Technion-IIT ftp server, and it is continuously expanded and corrected. The database is mirrored daily at an official mirror site, and at random at about a dozen unofficial mirror and 'finger' sites. The present edition contains numerous corrections and many recalculations of data of provisory type by the G3//B3LYP method, a high-accuracy composite ab initio calculation. About 300 species are newly calculated and are not yet published elsewhere. In anticipation of the full coupling, which is under development, the database started incorporating the available (as yet unpublished) values from Active Thermochemical Tables. The electronic version now also contains an XML file of the main database to allow transfer to other formats and ease finding specific information of interest. The database is used by scientists, educators, engineers and students at all levels, dealing primarily with combustion and air pollution, jet engines, rocket propulsion, fireworks, but also by researchers involved in upper atmosphere kinetics, astrophysics, abrasion metallurgy, etc. This introductory article contains explanations of the database and the means to use it, its sources, ways of calculation, and assessments of the accuracy of data.

Burcat, A.; Ruscic, B.; Chemistry; Technion - Israel Inst. of Tech.

2005-07-29

223

Combustion noise  

NASA Technical Reports Server (NTRS)

A review of the subject of combustion generated noise is presented. Combustion noise is an important noise source in industrial furnaces and process heaters, turbopropulsion and gas turbine systems, flaring operations, Diesel engines, and rocket engines. The state-of-the-art in combustion noise importance, understanding, prediction and scaling is presented for these systems. The fundamentals and available theories of combustion noise are given. Controversies in the field are discussed and recommendations for future research are made.

Strahle, W. C.

1977-01-01

224

Importance of activity data for improving the residential wood combustion emission inventory at regional level  

NASA Astrophysics Data System (ADS)

The contribution of residential wood combustion (RWC) to emission inventory at local level was estimated using a bottom-up approach for the Lombardy Region of North Italy. A survey, based on the CATI (Computer Assisted Telephone Interviewing) method, has been undertaken through 18,000 interviews. The interviews had the objective to characterize the RWC use in this region, in term of both total and municipal wood consumption. Details on the type of appliances used in RWC were also gathered. The results of the survey were then statistically analyzed in order to allow an estimate of RWC with high spatial resolution (i.e., at municipal level) in relation to the size and altitude of the territory. The work provides new evidence of the importance of wood combustion as a key source for PM and NMVOC emissions at local level, and thus highlights the importance of technological improvements and new policies aimed at emission reduction in this sector. Considering the great differences in average PM emission factors between low efficiency appliances (fireplaces, old stoves) and high efficiency ones (new stoves, pellet burners), this work emphasizes the importance of obtaining more detailed information on the types of wood appliances used for arriving at a reliable PM emission inventory for RWC.

Pastorello, Cinzia; Caserini, Stefano; Galante, Silvia; Dilara, Panagiota; Galletti, Fabio

2011-06-01

225

Synthesis, characterization and antimicrobial activity of some novel benzimidazole derivatives  

PubMed Central

A series of novel N-((1H-benzoimidazol-1-yl) methyl)-4-(1-phenyl-5-substituted-4, 5-dihydro-1-benzoimidazol-1-yl) methyl)-4-(1-phenyl-5-substituted-4, 5-dihydro-1H-pyrazol-3-yl) benzenamine were synthesized by treating various 1-(4-((1H-benzoimidazol-1-yl) methylamino) phenyl)-3-substitutedprop-2-en-1-one with phenyl hydrazine in the presence of sodium acetate through a simple ring closure reaction. The starting material, 1-(4-((1H-benzoimidazol-1-yl) methylamino) phenyl)-3-substitutedprop-2-en-1-one,-benzoimidazol-1-yl) methylamino) phenyl)-3-substitutedprop-2-en-1-one, was synthesized from o-phenylenediamine by a multistep synthesis. All the synthesized compounds were characterized by spectroscopic means and elemental analyses. The title compounds were investigated for in vitro antibacterial and antifungal properties against some human pathogenic microorganisms by employing the agar streak dilution method using Ciprofloxacin and Ketoconazole as standard drugs. All title compounds showed activity against the entire strains of microorganism. Structural activity relationship studies reveal that compounds possessing an electron-withdrawing group display better activity than the compounds containing electron-donating groups, whereas the unsubstituted derivatives display moderate activity. Based on the results obtained, N-((1H-benzoimidazol-1-yl) methyl)-4-(1-phenyl-5-(4-(trifluoromethyl) phenyl)-4,5-dihydro-1H-pyrazol-3-yl) benzenamine 5i was found to be very active compared with the rest of the compounds and standard drugs that were subjected to antimicrobial assay. PMID:24696814

Krishnanjaneyulu, Immadisetty Sri; Saravanan, Govindaraj; Vamsi, Janga; Supriya, Pamidipamula; Bhavana, Jarugula Udaya; Sunil Kumar, Mittineni Venkata

2014-01-01

226

Synthesis and characterization of LiMn 2O 4 powders by the combustion-assisted sol–gel technique  

Microsoft Academic Search

LiMn2O4 powders were prepared by heating the ignited LiMn2O4 precursor gel using lithium acetate, manganese acetate, citric acid and glycol as starting materials. The influence of synthesis conditions on the structural and electrochemical properties of LiMn2O4 was investigated by X-ray diffraction, scanning electron microscopy and charge–discharge experiments. The powders prepared under different conditions are of good crystallinity. The particle size,

Xian Ming Wu; Xin Hai Li; Zhuo Bing Xiao; Jianben Liu; Wen Bin Yan; Ming You Ma

2004-01-01

227

Synthesis and optical characterization of SrHfO3 nano-crystals synthesized by using the combustion method.  

PubMed

We synthesized SrHfO3 nano-crystals (NCs) by using the combustion method, and investigated their emission property using 325 nm photo-excitation. The as-grown SrHfO3 NCs were annealed at different temperatures from 700 degrees C to 1450 degrees C. The X-ray diffraction analysis revealed that all the samples are of a single phase, and the grain size increases with the higher temperature annealing. Interestingly, it is found that in contrast to the bulk case, the SrHfO3 NCs show a strong blue emission even at room temperature. The strong dependence of the visible emission on annealing temperatures and grain sizes indicated that the effects of grain size and oxygen vacancies may play a role in forming the observed visible emission band for SrHfO3 NCs. We also compare our findings with the case of similar material, SrZrO3. PMID:23755603

Kim, D H; Lee, D J; Park, J W; Lee, Y S

2013-03-01

228

One-step solution-combustion synthesis of complex spinel titanate flake particles with enhanced lithium-storage properties  

NASA Astrophysics Data System (ADS)

In this work, we report the formation of porous Li2MTi3O8 (M = Zn, Co) flakes (hereafter referred to as f-Li2MTi3O8) via a facile one-step solution-combustion in less than 10 min. As anodes for rechargeable lithium-ion batteries, the synthesized f-Li2MTi3O8 exhibits high reversible charge-discharge capacity, great cycling stability and high rate performance. These results can be attributed to the intrinsic characteristics of spinel Li2MTi3O8 flakes, in which a porous framework could provide a diffusion space for lithium ion insertion into and extraction from the anode material, resulting in excellent cycle performance, even cycling at high rate of 2000 mA g-1.

Li, Xue; Xiao, Qian; Liu, Bo; Lin, Huangchang; Zhao, Jinbao

2015-01-01

229

Synthesis and characterization of nano crystalline BaFe{sub 12}O{sub 19} powders by low temperature combustion  

SciTech Connect

Nano crystalline BaFe{sub 12}O{sub 19} powders have been prepared at a relatively low calcination temperature by a gel combustion technique using citric acid as a fuel/reductant and nitrates as oxidants. The effects of processing parameters, such as Ba/Fe ratio, citric acid/nitrates ratio, reaction temperature on the powder characteristics and magnetic properties of the resultant barium ferrites were investigated. By controlling the molar ratio of citric acid to metal nitrates, nano crystalline BaFe{sub 12}O{sub 19} powders with different particle sizes have been obtained. Phase attributes, microstructures and magnetic properties of the powders were characterized using X-ray diffraction analysis, X-ray line-broadening technique, Fourier transform infrared spectroscopy measurements, transmission electron microscopy and vibrating sample magnetometer. The maximum saturation magnetization value and intrinsic coercivity value for the obtained barium hexaferrites are 59.36 emu/g and 5540 Oe.

Huang Jianguo; Zhuang Hanrui; Li Wenlan

2003-01-01

230

Chemical synthesis and biological activity of rat INSL3.  

PubMed

The recently identified protein, insulin 3 (INSL3), has structural features that make it a bona fide member of the insulin superfamily. Its predicted amino acid sequence contains the classic two-peptide chain (A- and B-) structure with conserved cysteine residues that results in a disulphide bond disposition identical to that of insulin. Recently, the generation of insl3 knockout mice has demonstrated that testicular descent is blocked due to the failure of a specific ligament, the gubernaculum, to develop. The mechanism by which INSL3 exerts its action on the gubernaculum is currently unknown. The purpose of this study was to, for the first time, synthesize rat INSL3 and test its action on organ cultures of foetal rat gubernaculum. INSL3 also contains a cassette of residues Arg-X-X-X-Arg within the B-chain, a motif that is essential for characteristic activity of another related member of the superfamily, relaxin. Hence, the relaxin activity of rat INSL3 was also tested in two different relaxin bioassays. The primary structure of rat INSL3 was determined by deduction from its cDNA sequence and successfully prepared by solid phase peptide synthesis of the two constituent chains followed by their combination in solution. Following confirmation of its chemical integrity by a variety of analytical techniques, circular dichroism spectroscopy confirmed the presence of high beta-turn and alpha-helical content, with a remarkable spectral similarity to the synthetic ovine INSL3 peptide and to synthetic rat relaxin. The synthetic rat INSL3 bound with very low affinity to rat relaxin receptors and had no activity in a relaxin bioassay. Furthermore, it did not augment or antagonize relaxin activity. The rat INSL3 did however induce growth of foetal rat gubernaculum in whole organ cultures demonstrating that INSL3 has a direct action on this structure. PMID:11587188

Smith, K J; Wade, J D; Claasz, A A; Otvos, L; Temelcos, C; Kubota, Y; Hutson, J M; Tregear, G W; Bathgate, R A

2001-09-01

231

Synthesis, characterization and biological activities of curcumin nanospheres.  

PubMed

Curcumin is one of the most versatile compounds obtained from Curcuma longa. The major obstacle in the therapeutic use of curcumin is its aqueous solubility. To enhance its aqueous solubility and biological activities, we prepared curcumin nanospheres (CNSs) by wet milling-solvent evaporation technique without any surfactants. In this study, we have focused on the synthesis, characterization and biological effects of CNSs. DLS and SEM analyses showed 50-80 nm spherical shaped CNSs with a zeta potential of -31.65 mV. FTIR revealed that there were no structural changes to CNSs. Antibacterial and antifungal studies proved that CNSs were much more effective than curcumin against Escherichia coil, Staphylococcus aureus and Candida albicans. Antioxidant activity of CNSs showed promising result for therapeutic applications. The in vitro anti-inflammatory studies proved that CNSs possessed enhanced anti-inflammatory effect against protein denaturation. Cytotoxicity and uptake of CNSs showed more toxicity on cancer cells (T47D, MG63, A375) sparing normal HDF and IEC cell lines. Skin permeation studies showed CNSs retained at different layers of pig skin. These results give clear evidence for their use against microbial and fungal skin infections as well as cancer treatment. PMID:24738332

Arunraj, T R; Sanoj Rejinold, N; Mangalathillam, Sabitha; Saroj, Soumya; Biswas, Raja; Jayakumar, R

2014-02-01

232

Synthesis and photocatalytic activity of titania microspheres with hierarchical structures  

SciTech Connect

Research highlights: {yields} Lauryl alcohol directs the formation of titania with hierarchical structures. {yields} Hierarchical structures endow the higher specific area to titania. {yields} Titania had a higher photocatalytic activity than commercial Degussa P25. {yields} The synthesis process of the target product is low-cost. -- Abstract: A combined sol-gel and solvothermal process was introduced to fabricate the titania microspheres with hierarchical structures by using lauryl alcohol as the structure-directing agent. Scanning electron microscope, high-resolution transmission electron microscope, Fourier transform infrared spectrograph and powder X-ray powder diffraction indicated that the molar ratio of lauryl alcohol, water and tetra-n-butyl titanate was the key factor for the formation of the mono-dispersed titania with anatase phase and the optimal ratio was 1.2:4:1. The diameter of the end-product was 523 {+-} 74 nm and it was composed of smaller nanoparticles with about 6.8 nm size in diameter. Photocatalytic activity of the end-product was investigated by employing Rhodamine B and Methylene blue as the model compounds. The target microspheres exhibited the higher photocatalytic efficiency compared with commercial Degussa P25 titania and this result might be due to the hierarchical structures of microspheres according to the analysis of Brunauer-Emmett-Teller specific surface areas.

Cheng, Qian-Qian; Cao, Ying [College of Chemistry and Environmental Science, Henan Normal University, 46 East of Construction Road, Xinxiang 453007 (China)] [College of Chemistry and Environmental Science, Henan Normal University, 46 East of Construction Road, Xinxiang 453007 (China); Yang, Lin, E-mail: yanglin1819@163.com [College of Chemistry and Environmental Science, Henan Normal University, 46 East of Construction Road, Xinxiang 453007 (China)] [College of Chemistry and Environmental Science, Henan Normal University, 46 East of Construction Road, Xinxiang 453007 (China); Zhang, Pei-Pei; Wang, Kui; Wang, Hua-Jie [College of Chemistry and Environmental Science, Henan Normal University, 46 East of Construction Road, Xinxiang 453007 (China)] [College of Chemistry and Environmental Science, Henan Normal University, 46 East of Construction Road, Xinxiang 453007 (China)

2011-03-15

233

Sol-gel auto-combustion synthesis, structural and enhanced magnetic properties of Ni2+ substituted nanocrystalline Mg-Zn spinel ferrite  

NASA Astrophysics Data System (ADS)

Nanocrystalline arrays of Ni2+ substituted Mg-Zn spinel ferrite having a generic formula Mg0.7-xNixZn0.3Fe2O4 (x=0.0, 0.2, 0.4 and 0.6) were successfully synthesized by sol-gel auto-combustion technique. The fuel used in the synthesis process was citric acid and the metal nitrate-to-citric acid ratio was taken as 1:3. The phase, crystal structure and morphology of Mg-Ni-Zn ferrites were investigated by X-ray diffraction, scanning electron microscopy, and Fourier transformer infrared spectroscopy techniques. The lattice constant, crystallite size, porosity and cation distribution were determined from the X-ray diffraction data method. The FTIR spectroscopy is used to deduce the structural investigation and redistribution of cations between octahedral and tetrahedral sites of Mg-Ni-Zn spinel structured material. Morphological investigation suggests the formation of grain growth as the Ni2+ content x increases. The saturation magnetization and magneton number were determined from hysteresis loop technique. The saturation magnetization increases with increasing Ni2+ concentration ‘x’ in Mg-Zn ferrite.

Bobade, D. H.; Rathod, S. M.; Mane, Maheshkumar L.

2012-09-01

234

The effects of heat treatment on the synthesis of nickel ferrite (NiFe2O4) nanoparticles using the microwave assisted combustion method  

NASA Astrophysics Data System (ADS)

NiFe2O4 nanoparticles were synthesized using the microwave assisted combustion method based on metal nitrate salts and urea. To remain of organic matters and to stabilize the particles, samples were thermally treated at various temperatures from 300-800 °C. The prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) thermogravimetric analysis (TGA) and vibrating sample magnetometry (VSM). The heat treated samples show the reflection planes of (111), (220), (222), (311), (400), (422), (511), and (440) which perfectly confirm to a cubic spinel phase of NiFe2O4 and no secondary phases were detected in the XRD patterns of the samples. The crystallite sizes calculated using the Debye-Scherrer formula were found to increase with the heat treatment temperature, from about 4 nm at 300 °C-85 nm at 800 °C. EDX results verify that the compositional mass rations were relevant, as expected from the synthesis. The micrographs of SEM and TEM showed that all of the samples have nano-crystalline behavior and particles indication cubic shape. Magnetization measurements were obtained at room temperature by using a VSM, which demonstrated that the all of the samples synthesized with heat treatment exhibited ferromagnetic behaviors.

Karc?o?lu Karaka?, Zeynep; Boncukcuo?lu, Recep; Karaka?, ?brahim Hakk?; Ertu?rul, Mehmet

2015-01-01

235

Catalytic activity of oxidized (combusted) oil shale for removal of nitrogen oxides with ammonia as a reductant in combustion gas streams, Part 1  

SciTech Connect

Oxidized oil shale from the combustor in the LLNL hot recycle solids oil shale retorting process has been studied as a catalyst for removing nitrogen oxides from laboratory gas streams using NH{sub 3} as areductant. Combusted Green River oil shale heated at 10{degrees}C/min in an Ar/O{sub 2}/NO/NH{sub 3} mixture ({approximately}93%/6%/2000 ppm/4000 ppm) with a gas residence time of {approximately}0.6 sec exhibited NO removal between 250 and 500{degrees}C, with maximum removal of 70% at {approximately}400{degrees}C. Under isothermal conditions with the same gas mixture, the maximum NO removal was found to be {approximately}64%. When CO{sub 2} was added to the gas mixture at {approximately}8%, the NO removal dropped to {approximately}50%. However, increasing the gas residence time to {approximately}1.2 sec, increased NO removal to 63%. These results are not based on optimized process conditions, but indicate oxidized (combusted) oil shale is an effective catalyst for NO removal from combustion gas streams using NH{sub 3} as the reductant.

Reynolds, J.G.; Taylor, R.W.; Morris, C.J.

1992-06-10

236

Combustion synthesis and engineering nanoparticles for electronic, structural and superconductor applications. Final report, May 31, 1992--May 30, 1996  

SciTech Connect

Dense, nanocrystalline ceramic articles of doped ZrO{sub 2} (for use in solid electrolytes, oxygen sensors, electrode materials, thermal barrier coatings, etc.), BaTiO{sub 3} (for capacitor applications), and YBa{sub 2}Cu{sub 3}O{sub 7-x} (a high-temperature superconductor with uses, e.g., in magnetic flux trapping and high-speed capacitor applications) were prepared by the new nanofabrication process that has been developed in this research program. The process consists of two steps: synthesis of ceramic nanoparticles, and fabrication of dense ceramic articles that possess nanocrystalline features. The synthesis step is capable of producing 10-nanometer-diameter crystallites of doped ZrO{sub 2}, and of being scaled up to kilogram/hour production rates. The fabrication step produced dense, ultrafine-grained articles at significantly reduced sintering temperatures and times--representing a factor of 10-100 reduction in process energy requirements. The process has thus been shown to be technically feasible, while a preliminary engineering cost analysis of a pilot plant-scale version of the process indicates that it is both a cost- and an energy-efficient method of producing nanoparticles and nanocrystalline ceramics from those nanoparticles. One U.S. patent for this process has been allowed, and an additional five (continuation-in-part) applications have been filed. Technology transfer efforts have begun, through ongoing discussions with representatives from three manufacturing concerns.

Stangle, G.C.; Schulze, W.A.; Amarakoon, V.R.W.

1996-05-30

237

MICROWAVE-ASSISTED GREENER SYNTHESIS OF PHARMACEUTICALLY ACTIVE HETEROCYCLES UNDER BENIGN CONDITIONS  

EPA Science Inventory

Green chemistry is a rapidly developing new field that provides us a proactive avenue for the sustainable development of future science and technologies. Environmentally benign protocols have been developed for the synthesis of various pharmaceutically active heterocycles namely ...

238

The Synthesis of Active Metabolites and Analogues of Vitamin D3  

NASA Astrophysics Data System (ADS)

The literature date on the synthesis of the active metabolites and analogues of vitamin D3 (cholecalciferol), which play an important role in regulating the homeostatis of calcium in the organism, are reviewed. The bibliography includes 150 references.

Yakhimovich, R. I.

1980-04-01

239

Combustion synthesis of blue-emitting submicron CaAl4O7:Eu2+, Dy3+ persistence phosphor.  

PubMed

Long persistence phosphor CaAl4O7:Eu(2+), Dy(3+) were prepared by a combustion method. The phosphors were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), decay time measurement techniques and photoluminescence spectra (PL). The CaAl4O7:Eu(2+), Dy(3+) phosphor showed a broad blue emission, peaking at 445?nm when excited at 341?nm. Such a blue emission can be attributed to the intrinsic 4f???5d transitions of Eu(2+) in the host lattices. The lifetime decay curve of the Dy(3+) co-doped CaAl4O7:Eu(2+) phosphor contains a fast decay component and another slow decay one. Surface morphology also has been studied by SEM. The calculated CIE colour chromaticity coordinates was (0.227, 043). We have also discussed a possible long-persistent mechanism of CaAl4O7:Eu(2+), Dy(3+) phosphor. All the results indicate that this phosphor has promising potential for practical applications in the field of long-lasting phosphors for the purposes of sign boards and defence. PMID:22162513

Yerpude, A N; Dhoble, S J

2012-01-01

240

Rapid synthesis of mesoporous ceria-zirconia solid solutions via a novel salt-assisted combustion process  

SciTech Connect

Mesoporous ceria-zirconia solid solutions were prepared by a novel salt-assisted combustion process using ethylene glycol as a fuel and nitrate as an oxidant. The effects of various operating conditions such as the fuel-to-oxidant ratio and the nature and amount of added salt on the characteristics of the products were investigated by X-ray diffraction (XRD) and nitrogen adsorption analysis. Results from transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) showed that the introduction of leachable inert inorganic salt as a hard agglomeration inhibitor into the redox mixture precursor led to the breakup of fractal nanocrystallite agglomerates and the mesoporous structure formed by the loose agglomeration of monodispersed nanoparticles, which was also confirmed by small-angle XRD and nitrogen adsorption analysis. The presence of salt was found to result in a more than 10-fold increase in the specific surface area of the products from 17.34 to 208.17 m{sup 2}/g at a given molar ratio of ethylene glycol-nitrate. A mechanism scheme was proposed to illustrate the possible formation processes and discuss the role of the salt additives.

Chen Weifan [National Special Superfine Powder Engineering Research Center, Nanjing University of Science and Technology, Xiaolingwei 200, Nanjing, Jiangsu 210094 (China)]. E-mail: weifan-chen@163.com; Li Fengsheng [National Special Superfine Powder Engineering Research Center, Nanjing University of Science and Technology, Xiaolingwei 200, Nanjing, Jiangsu 210094 (China); Yu Jiyi [National Special Superfine Powder Engineering Research Center, Nanjing University of Science and Technology, Xiaolingwei 200, Nanjing, Jiangsu 210094 (China); Liu Leili [College of Chemical Engineering, Shandong Institute of Light Industry, Jinan 250100 (China); Gao Hailian [National Special Superfine Powder Engineering Research Center, Nanjing University of Science and Technology, Xiaolingwei 200, Nanjing, Jiangsu 210094 (China)

2006-12-14

241

Synthesis and antiestrogenic activity of diaryl thioether derivatives.  

PubMed

The reaction of 1,2-diarylethanol and mercapto side chain catalyzed by ZnI2 was used as a key step in the short (three to five steps) and efficient synthesis of 17 diaryl thioether derivatives. Several of these compounds contain a methyl butyl amide chain and an hydroxyaryl moiety, respectively, for antiestrogenic activity and binding affinity on estrogen receptor. No binding affinity for crude cytosolic preparation of the estrogen receptor was observed for compounds without phenolic group, while a low affinity (0.01-0.05%) was measured for mono- or diphenol derivatives. Like the pure steroidal antiestrogen EM-139, these novel nonsteroidal compounds did not exert any stimulatory effect on cell proliferation of (ER+) ZR-75-1 human breast cancer cells and partially reversed the amplitude of the stimulatory effect induced by estradiol on this (ER+) cell line. No proliferative or antiproliferative effect on (ER-) MDA-MB-231 human breast cancer cells was also observed for three of these compounds (39-41). Among the newly synthesized nonsteroidal compounds, the thioether derivative 41 (N-butyl-N-methyl-13,14-bis(4'-hydroxyphenyl)-12-thiatetradecanamide+ ++), with a long methylbutylalkanamide side chain and a diphenolic nucleus, was selected as the best antiestrogenic compound. However, this compound was 100-fold less antiestrogenic in (ER+) ZR-75-1 cells than the steroidal antiestrogen EM-139. PMID:8164253

Poirier, D; Auger, S; Mérand, Y; Simard, J; Labrie, F

1994-04-15

242

Activation of AMP-activated protein kinase inhibits protein synthesis associated with hypertrophy in the cardiac myocyte.  

PubMed

A necessary mediator of cardiac myocyte enlargement is protein synthesis, which is controlled at the levels of both translation initiation and elongation. Eukaryotic elongation factor-2 (eEF2) mediates the translocation step of peptide-chain elongation and is inhibited through phosphorylation by eEF2 kinase. In addition, p70S6 kinase can regulate protein synthesis by phosphorylating eEF2 kinase or via phosphorylation of ribosomal protein S6. We have recently shown that eEF2 kinase is also controlled by phosphorylation by AMP-activated protein kinase (AMPK), a key regulator of cellular energy homeostasis. Moreover, the mammalian target of rapamycin has also been shown to be inhibited, indirectly, by AMPK, thus leading to the inhibition of p70S6 kinase. Although AMPK activation has been shown to modulate protein synthesis, it is unknown whether AMPK could also be a regulator of cardiac hypertrophic growth. Therefore, we investigated the role of AMPK activation in regulating protein synthesis during both phenylephrine- and Akt-induced cardiac hypertrophy. Metformin and 5-aminoimidazole-4-carboxamide 1-beta-D-ribofuranoside were used to activate AMPK in neonatal rat cardiac myocytes. Activation of AMPK significantly decreased protein synthesis induced by phenylephrine treatment or by expression of constitutively active Akt. Activation of AMPK also resulted in decreased p70S6 kinase phosphorylation and increased phosphorylation of eEF2, suggesting that inhibition of protein synthesis involves the eEF2 kinase/eEF2 axis and/or the p70S6 kinase pathway. Together, our data suggest that the inhibition of protein synthesis by pharmacological activation of AMPK may be a key regulatory mechanism by which hypertrophic growth can be controlled. PMID:15159410

Chan, Anita Y M; Soltys, Carrie-Lynn M; Young, Martin E; Proud, Christopher G; Dyck, Jason R B

2004-07-30

243

Combustion in fluidized beds  

Microsoft Academic Search

Circulating fluidized-bed (CFB) combustion systems have become popular since the late 1970s, and, given the current level of activity in the area,it is clear that this technology has a stable future in the boiler market. For standard coal combustion applications, competition is fierce with mature pulverized-fuel-based (PF) technology set to maintain a strong profile. CFB systems, however, can be more

F. J. Dry; R. D. La Nauze

1990-01-01

244

Synthesis and antibacterial activity evaluation of two androgen derivatives.  

PubMed

In this study two androgen derivatives were synthesized using several strategies; the first stage an aza-steroid derivative (3) was developed by the reaction of a testosterone derivative (1) with thiourea (2) in presence of hydrogen chloride. The second step, involves the synthesis of an amino-steroid derivative (4) by the reaction of 1 with 2 using boric acid as catalyst. The third stage was achieved by the preparation of an aminoaza-androgen derivative (6) by the reaction of 3 with ethylenediamine using boric acid as catalyst. In addition, the compound 6 was made reacting with dihydrotestosterone to form a new androgen derivative (7) in presence of boric acid. The following step was achieved by the reaction of 7 with chloroacetyl chloride to synthesize an azetidinone-androgen derivative (8) using triethylamine as catalyst. Additionally, a thiourea-androgen derivative (9) was synthetized by the reaction of 4 with dihydrotestosterone using boric acid as catalyst. Finally, the compound 9 was made reacting with chloroacetyl chloride in presence of triethylamine to synthesize a new azetidinone-androgen derivative (10). On the other hand, antibacterial activity of compounds synthesized was evaluated on Gram negative (Escherichia coli and Vibrio cholerae) and Gram positive (Staphylococos aureus) bacteria. The results indicate that only the compound 3 and 8 decrease the growth bacterial of E. coli and V. cholerae. Nevertheless, growth bacterial of S. aureus was not inhibited by these compounds. These data indicate that antibacterial activity exerted by the compounds 3 and 8 depend of their structure chemical in comparison with the controls and other androgen derivatives that are involved in this study. PMID:25448363

Lauro, Figueroa-Valverde; Francisco, Díaz-Cedillo; Elodia, García-Cervera; Eduardo, Pool-Gómez; Maria, López-Ramos; Marcela, Rosas-Nexticapa; Lenin, Hau-Heredia; Bety, Sarabia-Alcocer

2015-01-01

245

Laccase Catalyzed Synthesis of Iodinated Phenolic Compounds with Antifungal Activity  

PubMed Central

Iodine is a well known antimicrobial compound. Laccase, an oxidoreductase which couples the one electron oxidation of diverse phenolic and non-phenolic substrates to the reduction of oxygen to water, is capable of oxidizing unreactive iodide to reactive iodine. We have shown previously that laccase-iodide treatment of spruce wood results in a wash-out resistant antimicrobial surface. In this study, we investigated whether phenolic compounds such as vanillin, which resembles sub-structures of softwood lignin, can be directly iodinated by reacting with laccase and iodide, resulting in compounds with antifungal activity. HPLC-MS analysis showed that vanillin was converted to iodovanillin by laccase catalysis at an excess of potassium iodide. No conversion of vanillin occurred in the absence of enzyme. The addition of redox mediators in catalytic concentrations increased the rate of iodide oxidation ten-fold and the yield of iodovanillin by 50%. Iodinated phenolic products were also detected when o-vanillin, ethyl vanillin, acetovanillone and methyl vanillate were incubated with laccase and iodide. At an increased educt concentration of 0.1 M an almost one to one molar ratio of iodide to vanillin could be used without compromising conversion rate, and the insoluble iodovanillin product could be recovered by simple centrifugation. The novel enzymatic synthesis procedure fulfills key criteria of green chemistry. Biocatalytically produced iodovanillin and iodo-ethyl vanillin had significant growth inhibitory effects on several wood degrading fungal species. For Trametes versicolor, a species causing white rot of wood, almost complete growth inhibition and a partial biocidal effect was observed on agar plates. Enzymatic tests indicated that the iodinated compounds acted as enzyme responsive, antimicrobial materials. PMID:24594755

Ihssen, Julian; Schubert, Mark; Thöny-Meyer, Linda; Richter, Michael

2014-01-01

246

Cooperative upconversion luminescence in Tb{sup 3+}:Yb{sup 3+} co-doped Y{sub 2}SiO{sub 5} powders prepared by combustion synthesis  

SciTech Connect

Frequency upconversion (UC) luminescence via cooperative energy transfer (CET) process between pairs of Yb{sup 3+} and Tb{sup 3+} ions was investigated in Tb{sup 3+}:Yb{sup 3+}:Y{sub 2}SiO{sub 5} crystalline ceramic powders prepared by combustion synthesis. Surface morphology and structure of the powders were investigated by scanning electronic microscopy and X-ray powder diffraction. Photoluminescence experiments were performed in Tb{sup 3+}-singly doped samples using ultraviolet light (?=255 nm) and in Tb{sup 3+}:Yb{sup 3+} co-doped samples using a near-infrared (NIR) diode laser (?=975 nm). Upon excitation with the NIR diode laser, UC luminescence with an intense emission band centered at ?549 nm, corresponding to the 4f intraband {sup 5}D{sub 4}?{sup 7}F{sub 5} transition of Tb{sup 3+}, along with less intense emission bands at ?490, ?590 and ?620 nm, corresponding to other {sup 5}D{sub 4}?{sup 7}F{sub J} transitions, was detected. The CET rate was estimated by analyzing the dynamics of UC luminescence with rate equations model of the electronic populations. -- Graphical Abstract: Left: Cooperative upconversion luminescence spectra of three powder samples prepared by combustion synthesis. Right: The SEM image of the powder showing that it consists of agglomerated flake-like shaped particles of various sizes. Full scale bar is 20 ?m. Highlights: • Yttrium orthosilicate (Y{sub 2}SiO{sub 5}) powders were prepared by combustion synthesis. • Cooperative upconversion is observed for the first time in Tb{sup 3+}–Yb{sup 3+} doped Y{sub 2}SiO{sub 5}. • Energy transfer and back-transfer rates between Tb{sup 3+} and Yb{sup 3+} pairs were estimated.

Rakov, Nikifor, E-mail: nikifor.gomez@univasf.edu.br [PG - Ciência dos Materiais, Universidade Federal do Vale do São Francisco, 48902-300 Juazeiro, BA (Brazil); Vieira, Simone A. [PG - Ciência dos Materiais, Universidade Federal do Vale do São Francisco, 48902-300 Juazeiro, BA (Brazil); Guimarães, Renato B. [Instituto de Física, Universidade Federal Fluminense, 24210-346 Niterói, RJ (Brazil); Maciel, Glauco S., E-mail: glauco@if.uff.br [Instituto de Física, Universidade Federal Fluminense, 24210-346 Niterói, RJ (Brazil)

2014-03-15

247

Combustion synthesis and effect of LaMnO3 and La0.8Sr0.2MnO3 on RDX thermal decomposition.  

PubMed

Perovskite-type LaMnO(3) and La(0.8)Sr(0.2)MnO(3) with high specific surface areas were prepared by stearic acid gel combustion method. The obtained powders were characterized by XRD, FT-IR, SEM and XPS techniques. Their catalytic activities were investigated on thermal decomposition of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) by TG-DSC techniques. The experimental results show that LaMnO(3) is a more effective catalyst than La(0.8)Sr(0.2)MnO(3) for the sublimation and melting process of RDX because of its higher concentration ratio of surface-adsorbed species. And the catalytic activity of La(0.8)Sr(0.2)MnO(3) is higher than that of LaMnO(3) for thermal decomposition of liquid RDX. This could be attributed to its higher concentration ratios of surface oxygen and Mn(4+)/Mn(3+). In conclusion, the concentration ratios of surface oxygen and Mn(4+)/Mn(3+) could play key roles for RDX thermal decomposition. This study points out a potential way to develop new and more active perovskite-type catalysts for the RDX thermal decomposition. PMID:20060210

Wei, Zhi-Xian; Wei, Lin; Gong, Lin; Wang, Yan; Hu, Chang-Wen

2010-05-15

248

A simple aloe vera plant-extracted microwave and conventional combustion synthesis: Morphological, optical, magnetic and catalytic properties of CoFe2O4 nanostructures  

NASA Astrophysics Data System (ADS)

Nanocrystalline magnetic spinel CoFe2O4 was synthesized by a simple microwave combustion method (MCM) using ferric nitrate, cobalt nitrate and Aloe vera plant extracted solution. For the comparative study, it was also prepared by a conventional combustion method (CCM). Powder X-ray diffraction, energy dispersive X-ray and selected-area electron diffraction results indicate that the as-synthesized samples have only single-phase spinel structure with high crystallinity and without the presence of other phase impurities. The crystal structure and morphology of the powders were revealed by high resolution scanning electron microscopy and transmission electron microscopy, show that the MCM products of CoFe2O4 samples contain sphere-like nanoparticles (SNPs), whereas the CCM method of samples consist of flake-like nanoplatelets (FNPs). The band gap of the samples was determined by UV-Visible diffuse reflectance and photoluminescence spectroscopy. The magnetization (Ms) results showed a ferromagnetic behavior of the CoFe2O4 nanostructures. The Ms value of CoFe2O4-SNPs is higher i.e. 77.62 emu/g than CoFe2O4-FNPs (25.46 emu/g). The higher Ms value of the sample suggest that the MCM technique is suitable for preparing high quality nanostructures for magnetic applications. Both the samples were successfully tested as catalysts for the conversion of benzyl alcohol. The resulting spinel ferrites were highly selective for the oxidation of benzyl alcohol and exhibit important difference among their activities. It was found that CoFe2O4-SNPs catalyst show the best performance, whereby 99.5% selectivity of benzaldehyde was achieved at close to 93.2% conversion.

Manikandan, A.; Sridhar, R.; Arul Antony, S.; Ramakrishna, Seeram

2014-11-01

249

Investigating the performance of CoxOy/activated carbon catalysts for ethyl acetate catalytic combustion  

NASA Astrophysics Data System (ADS)

The catalytic properties of Co-supported activated carbon (AC) catalysts for ethyl acetate catalytic elimination in air were investigated. Results showed that air atmosphere promoted the generation of high-valence state cobalt oxides, and promote the production of reactive oxygen species (ROS) in the Co3O4/AC catalyst. ROS crucially functioned in improving the catalytic activity of Co3O4/AC catalysts. Therefore, CoACA catalyst prepared in air exhibited higher catalytic activity than CoACN catalyst prepared in nitrogen, and CoACA catalyst led to high ethyl acetate conversion (>93%) and stability at a low reaction temperature (210 °C).

Xie, Hongmei; Zhao, Xiaoping; Zhou, Guilin; He, Xiaoling; Lan, Hai; Jiang, Zongxuan

2015-01-01

250

The rate of synthesis and decomposition of tissue proteins in hypokinesia and increased muscular activity  

NASA Technical Reports Server (NTRS)

During hypokinesia and physical loading (swimming) of rats, the radioactivity of skeletal muscle, liver, kidney, heart, and blood proteins was determined after administration of radioactive amino acids. Tissue protein synthesis decreased during hypokinesia, and decomposition increased. Both synthesis and decomposition increased during physical loading, but anabolic processes predominated in the total tissue balance. The weights of the animals decreased in hypokinesia and increased during increased muscle activity.

Fedorov, I. V.; Chernyy, A. V.; Fedorov, A. I.

1978-01-01

251

Internal combustion engine using premixed combustion of stratified charges  

DOEpatents

During a combustion cycle, a first stoichiometrically lean fuel charge is injected well prior to top dead center, preferably during the intake stroke. This first fuel charge is substantially mixed with the combustion chamber air during subsequent motion of the piston towards top dead center. A subsequent fuel charge is then injected prior to top dead center to create a stratified, locally richer mixture (but still leaner than stoichiometric) within the combustion chamber. The locally rich region within the combustion chamber has sufficient fuel density to autoignite, and its self-ignition serves to activate ignition for the lean mixture existing within the remainder of the combustion chamber. Because the mixture within the combustion chamber is overall premixed and relatively lean, NO.sub.x and soot production are significantly diminished.

Marriott, Craig D. (Rochester Hills, MI); Reitz, Rolf D. (Madison, WI

2003-12-30

252

DETECTION OF ANDROGENIC ACTIVITY IN EMISSIONS FROM DIESEL FUEL AND BIOMASS COMBUSTION  

EPA Science Inventory

The present study evaluated both diesel fuel exhaust and biomass (wood) burn extracts for androgen receptor¿mediated activity using MDA-kb2 cells, which contain an androgen-responsive promoter-luciferase reporter gene construct. This assay and analytical fractionization of the sa...

253

Preparation, luminescence and defect studies of Eu{sup 2+}-activated strontium hexa-aluminate phosphor prepared via combustion method  

SciTech Connect

Preparation of Eu{sup 2+} ions activated strontium hexa-aluminate phosphor using the combustion method is described. An efficient phosphor can be prepared by this method at reaction temperatures as low as 500 deg. C in a few minutes. Powder X-ray diffraction (XRD), transmission electron microscopy, scanning electron microscope analysis were used to characterize the as prepared product and the optical properties were studied by photoluminescence (PL) spectra. Thermally stimulated luminescence studies also have been carried out on SrAl{sub 12}O{sub 19}:Eu{sup 2+} phosphor. The TSL glow curve is broad and indicates two dominant peaks at 206 and 345 deg. C. Defect centres formed in irradiated phosphor have been studied using the technique of electron spin resonance. One of the centres is characterized by an isotropic g-value of 2.0055 and is assigned to a F{sup +} centre. The two annealing stages of F{sup +} centre in the region 125-230 and 340-390 deg. C appear to correlate with the release of carriers resulting in TSL peaks at 206 and 345 deg. C, respectively. - Graphical abstract: SEM image of SrAl{sub 12}O{sub 19}:Eu.

Singh, Vijay [Key Lab of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Gundu Rao, T.K. [R.S.I.C., Indian Institute of Technology, Powai, Mumbai 400 076 (India); Zhu Junjie [Key Lab of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China)]. E-mail: jjzhu@nju.edu.cn

2006-08-15

254

Catalytic activity of oxidized (combusted) oil shale for removal of nitrogen oxides with ammonia as a reductant in combustion gas streams, Part 2  

SciTech Connect

Oxidized oil shale from the combustor in the LLNL Hot-Recycled-Solids (HRS) oil shale retorting process has been found to be a catalyst for removing nitrogen oxides from laboratory gas streams using NH[sub 3] as a reductant. Oxidized Green River oil shale heated at 10[degree]C/min in an Ar/O[sub 2]/NO/NH[sub 3] mixture ([approximately]93%/6%/2000 ppM/4000 ppM) with a gas residence time of [approximately]0.6 sec removed NO between 250 and 500[degree]C, with maximum removal of 70% at [approximately]400[degree]C. Under isothermal conditions with the same gas mixture, the maximum NO removal was [approximately]64%. When CO[sub 2] was added to the gas mixture at [approximately]8%, the NO removal dropped to [approximately]50%. However, increasing the gas residence time to [approximately]1.2 sec, increased NO removal to 63%. Nitrogen balances of these experiments suggest selective catalytic reduction of NO is occurring using NH[sub 3] as the reductant. These results are not based on completely optimized process conditions, but indicate oxidized oil shale is an effective catalyst for NO removal from combustion gas streams using NH[sub 3] as the reductant. Parameters calculated for implementing oxidized oil shale for NO[sub x] remediation on the current HRS retort indicate an abatement device is practical to construct.

Reynolds, J.G.; Taylor, R.W.; Morris, C.J.

1993-01-04

255

Catalytic activity of oxidized (combusted) oil shale for removal of nitrogen oxides with ammonia as a reductant in combustion gas streams, Part 2  

SciTech Connect

Oxidized oil shale from the combustor in the LLNL Hot-Recycled-Solids (HRS) oil shale retorting process has been found to be a catalyst for removing nitrogen oxides from laboratory gas streams using NH{sub 3} as a reductant. Oxidized Green River oil shale heated at 10{degree}C/min in an Ar/O{sub 2}/NO/NH{sub 3} mixture ({approximately}93%/6%/2000 ppM/4000 ppM) with a gas residence time of {approximately}0.6 sec removed NO between 250 and 500{degree}C, with maximum removal of 70% at {approximately}400{degree}C. Under isothermal conditions with the same gas mixture, the maximum NO removal was {approximately}64%. When CO{sub 2} was added to the gas mixture at {approximately}8%, the NO removal dropped to {approximately}50%. However, increasing the gas residence time to {approximately}1.2 sec, increased NO removal to 63%. Nitrogen balances of these experiments suggest selective catalytic reduction of NO is occurring using NH{sub 3} as the reductant. These results are not based on completely optimized process conditions, but indicate oxidized oil shale is an effective catalyst for NO removal from combustion gas streams using NH{sub 3} as the reductant. Parameters calculated for implementing oxidized oil shale for NO{sub x} remediation on the current HRS retort indicate an abatement device is practical to construct.

Reynolds, J.G.; Taylor, R.W.; Morris, C.J.

1993-01-04

256

Calotropis procera mediated combustion synthesis of ZnAl2O4:Cr3+ nanophosphors: Structural and luminescence studies  

NASA Astrophysics Data System (ADS)

ZnAl2O4:Cr3+ nanophosphors were synthesized for the first time by a simple and environment friendly route using Calotropis procera milk latex as fuel. The structural and surface morphological studies were carried out using powder X-ray diffraction (PXRD), scanning electron microscopy and transmission electron microscopy techniques. The photoluminescence (PL) properties of ZnAl2O4:Cr3+ as a function of dopant concentration and calcination temperature was studied in detail. The PXRD patterns and Rietveld confinement confirmed the cubic crystal system with space group Fd-3m. The crystallite size estimated from Scherrer's and W-H plots was found to be in the range of 16-26 nm. The PL spectrum shows an intense peak at ?688 and ?699 nm assigned to spin - forbidden 2Eg ? 4A2g transition of Cr3+ ions. The PL measurements for two excitations (?410 and 527 nm) and with respect to calcination temperature indicated no significant change in the shape and position of emission peak except PL intensity. The CIE chromaticity coordinates lies well within the white region. Thermoluminescence (TL) studies revealed well resolved glow peak at ?212 °C with a small shoulder at 188 and 233 °C. The glow peak intensity at ?212 °C increases linearly with ?-dose which suggest ZnAl2O4:Cr3+ is suitable candidate for radiation dosimetric applications. The activation energy (E in eV), order of kinetics (b) and Frequency factor (s) were estimated using glow peak shape method.

Ravikumar, B. S.; Nagabhushana, H.; Sharma, S. C.; Vidya, Y. S.; Anantharaju, K. S.

2015-02-01

257

Calotropis procera mediated combustion synthesis of ZnAl2O4:Cr(3+) nanophosphors: Structural and luminescence studies.  

PubMed

ZnAl2O4:Cr(3+) nanophosphors were synthesized for the first time by a simple and environment friendly route using Calotropis procera milk latex as fuel. The structural and surface morphological studies were carried out using powder X-ray diffraction (PXRD), scanning electron microscopy and transmission electron microscopy techniques. The photoluminescence (PL) properties of ZnAl2O4:Cr(3+) as a function of dopant concentration and calcination temperature was studied in detail. The PXRD patterns and Rietveld confinement confirmed the cubic crystal system with space group Fd-3m. The crystallite size estimated from Scherrer's and W-H plots was found to be in the range of 16-26nm. The PL spectrum shows an intense peak at ?688 and ?699nm assigned to spin - forbidden (2)Eg?(4)A2g transition of Cr(3+) ions. The PL measurements for two excitations (?410 and 527nm) and with respect to calcination temperature indicated no significant change in the shape and position of emission peak except PL intensity. The CIE chromaticity coordinates lies well within the white region. Thermoluminescence (TL) studies revealed well resolved glow peak at ?212°C with a small shoulder at 188 and 233°C. The glow peak intensity at ?212°C increases linearly with ?-dose which suggest ZnAl2O4:Cr(3+) is suitable candidate for radiation dosimetric applications. The activation energy (E in eV), order of kinetics (b) and Frequency factor (s) were estimated using glow peak shape method. PMID:25459629

Ravikumar, B S; Nagabhushana, H; Sharma, S C; Vidya, Y S; Anantharaju, K S

2015-02-01

258

Design, diversity-oriented synthesis and structure activity relationship studies of quinolinyl heterocycles as antimycobacterial agents.  

PubMed

The current study reports design and diversity oriented synthesis of novel bis heterocycles with a common 2-methyl, C-4 unsubstituted quinoline moiety as the central key heterocycle. Employing reagent based skeletal diversity approach; a facile synthesis of bis heterocycles with different heterocyclic rings at C-3 position of the quinoline moiety has been accomplished. A broad range of heterocyclic frameworks thus obtained were evaluated for their antimycobacterial activity. The active scaffolds were further explored by a parallel library generation in order to establish SAR. Further, low cytotoxicity against A549 cell line enhances the potential of the synthesized molecules as promising antimycobacterial agents. PMID:24189497

Rachakonda, Venkatesham; Alla, Manjula; Kotipalli, Sudha Sravanti; Ummani, Ramesh

2013-01-01

259

Ionic liquid self-combustion synthesis of BiOBr/Bi24O31Br10 heterojunctions with exceptional visible-light photocatalytic performances.  

PubMed

Heterostructured BiOBr/Bi24O31Br10 nanocomposites with surface oxygen vacancies are constructed by a facile in situ route of one-step self-combustion of ionic liquids. The compositions can be easily controlled by simply adjusting the fuel ratio of urea and 2-bromoethylamine hydrobromide (BTH). BTH serves not only as a fuel, but also as a complexing agent for ionic liquids and a reactant to supply the Br element. The heterojunctions show remarkable adsorptive ability for both the cationic dye of rhodamine B (RhB) and the anionic dye of methylene orange (MO) at high concentrations, which is attributed to the abundant surface oxygen vacancies. The sample containing 75.2% BiOBr and 24.8% Bi24O31Br10 exhibits the highest photocatalytic activity. Its reaction rate constant is 4.0 and 9.0 times that of pure BiOBr in degrading 50 mg L(-1) of RhB and 30 mg L(-1) of MO under visible-light (? > 400 nm) irradiation, respectively, which is attributed to the narrow band gap and highly efficient transfer efficiency of charge carriers. Different photocatalytic reaction processes and mechanisms over pure BiOBr and heterojunctions are proposed. PMID:25482071

Li, Fa-Tang; Wang, Qing; Ran, Jingrun; Hao, Ying-Juan; Wang, Xiao-Jing; Zhao, Dishun; Qiao, Shi Zhang

2014-12-18

260

Transgalactosylation and hydrolytic activities of commercial preparations of ?-galactosidase for the synthesis of prebiotic carbohydrates.  

PubMed

?-Galactosidases exhibit both hydrolytic and transgalactosylation activities; the former has been used traditionally for the production of delactosed milk and dairies, while the latter is being increasingly used for the synthesis of lactose-derived oligosaccharides: balance between both activities was highly dependent on the enzyme origin: ?-galactosidases from Aspegillus oryzae and Bacillus circulans exhibited high transgalactosylation activity, while those from one from Kluyveromyces exhibited high hydrolytic activity but quite low transgalactosylation activity. Also the affinity for the donors (lactose or lactulose) and the acceptors (lactose, lactulose or fructose) of transgalactosylated galactose was dependent on the enzyme origin, as reflected by the Michaelis constants obtained in the synthesis of galacto-oligosaccharides, fructosyl-galacto-oligosaccharides and lactulose. Finally, the balance between transgalactosylation and hydrolytic activities of ?-galactosidases could be tuned by changing the concentration of galactose donor. PMID:25659627

Guerrero, Cecilia; Vera, Carlos; Conejeros, Raúl; Illanes, Andrés

2015-03-01

261

Synthesis and biological activity of enantiomers of antitumor irofulven.  

PubMed

Stereoselective synthesis of (-)-irofulven has been achieved by cycloaddition of (R)-5-chloro-5-methyl-2-cyclopentenone to the 1,3-dipolar intermediate from 1-acetyl-1-(diazoacetyl)cyclopropane. The enantiomer, (+)-irofulven, was prepared in a similar way starting with (S)-5-chloro-5-methyl-2-cyclopentenone. (+)-Irofulven was 5 to 6 times less toxic than (-)-irofulven to adenocarcinoma (MV 522) cells. PMID:14750783

McMorris, Trevor C; Staake, Michael D; Kelner, Michael J

2004-02-01

262

Preparation and activity of the catalysts for the synthesis of carboxylic ester with high boiling point  

Microsoft Academic Search

A series of rare earth sulfates catalysts were prepared by hot-impregnation method from rare earth oxides and sulfuric acid, followed by calcination and activation at 470–500°C. Using the synthesis of dibutyl phthalate as test reaction, the catalytic activities of samples were examined in detail, especially about the activities of ceric sulfate containing hydrate water and its composite with transition metal

Dongyan Tang; Juying Huang; Yuhong Zhou; Yuqiang Zhang; Qingyan Chen

1999-01-01

263

Reactive Oxygen Species-dependent RhoA Activation Mediates Collagen Synthesis in Hyperoxic Lung Fibrosis  

PubMed Central

Lung fibrosis is an ultimate consequence of pulmonary oxygen toxicity in human and animal models. Excessive production and deposition of extracellular matrix proteins, e. g. collagen-I, is the most important feature of pulmonary fibrosis in hyperoxia-induced lung injury. In the present study, we investigated the role of RhoA and reactive oxygen species (ROS) in collagen-I synthesis in hyperoxic lung fibroblasts and in a mouse model of oxygen toxicity. Exposure of human lung fibroblasts to hyperoxia resulted in RhoA activation and increase in collagen-I synthesis and cell proliferation. Inhibition of RhoA by C3 transferase CT-04, dominant-negative RhoA mutant T19N, or RhoA siRNA prevented hyperoxia-induced collagen-I synthesis. Constitutively active RhoA mutant Q63L mimicked the effect of hyperoxia on collagen-I expression. Moreover, Rho kinase (ROCK) inhibitor Y27632 inhibited collagen-I synthesis in hyperoxic lung fibroblasts and fibrosis in mouse lungs after oxygen toxicity. Furthermore, ROS scavenger tiron attenuated hyperoxia-induced increases in RhoA activation and collagen-I synthesis in lung fibroblasts and mouse lungs after oxygen toxicity. More importantly, we found that hyperoxia induced separation of guanine nucleotide dissociation inhibitor (GDI) from RhoA in lung fibroblasts and mouse lungs. Further, tiron prevented the separation of GDI from RhoA in hyperoxic lung fibroblasts and mouse lungs with oxygen toxicity. Together, these results indicate that ROS-induced separation of GDI from RhoA leads to RhoA activation with oxygen toxicity. ROS-dependent RhoA activation is responsible for the increase in collagen-I synthesis in hyperoxic lung fibroblasts and mouse lungs. PMID:21439370

Kondrikov, Dmitry; Caldwell, Ruth B.; Dong, Zheng; Su, Yunchao

2011-01-01

264

Reactive oxygen species-dependent RhoA activation mediates collagen synthesis in hyperoxic lung fibrosis.  

PubMed

Lung fibrosis is an ultimate consequence of pulmonary oxygen toxicity in human and animal models. Excessive production and deposition of extracellular matrix proteins, e.g., collagen-I, is the most important feature of pulmonary fibrosis in hyperoxia-induced lung injury. In this study, we investigated the roles of RhoA and reactive oxygen species (ROS) in collagen-I synthesis in hyperoxic lung fibroblasts and in a mouse model of oxygen toxicity. Exposure of human lung fibroblasts to hyperoxia resulted in RhoA activation and an increase in collagen-I synthesis and cell proliferation. Inhibition of RhoA by C3 transferase CT-04, dominant-negative RhoA mutant T19N, or RhoA siRNA prevented hyperoxia-induced collagen-I synthesis. The constitutively active RhoA mutant Q63L mimicked the effect of hyperoxia on collagen-I expression. Moreover, the Rho kinase inhibitor Y27632 inhibited collagen-I synthesis in hyperoxic lung fibroblasts and fibrosis in mouse lungs after oxygen toxicity. Furthermore, the ROS scavenger tiron attenuated hyperoxia-induced increases in RhoA activation and collagen-I synthesis in lung fibroblasts and mouse lungs after oxygen toxicity. More importantly, we found that hyperoxia induced separation of guanine nucleotide dissociation inhibitor (GDI) from RhoA in lung fibroblasts and mouse lungs. Further, tiron prevented the separation of GDI from RhoA in hyperoxic lung fibroblasts and mouse lungs with oxygen toxicity. Together, these results indicate that ROS-induced separation of GDI from RhoA leads to RhoA activation with oxygen toxicity. ROS-dependent RhoA activation is responsible for the increase in collagen-I synthesis in hyperoxic lung fibroblasts and mouse lungs. PMID:21439370

Kondrikov, Dmitry; Caldwell, Ruth B; Dong, Zheng; Su, Yunchao

2011-06-01

265

Synthesis and characterization of Gd{sup 3+} and Nd{sup 3+} co-doped ceria by using citric acid-nitrate combustion method  

SciTech Connect

A series of Ce{sub 0.8}Gd{sub 0.2-x}Nd{sub x}O{sub 2-{delta}} (x = 0-0.20) compositions have been synthesized by citric acid-nitrate combustion method. XRD measurements indicate that all the obtained materials crystallized in cubic fluorite-type structure. Lattice parameters were calculated by Rietveld method and the parameter a values in Ce{sub 0.8}Gd{sub 0.2-x}Nd{sub x}O{sub 2-{delta}} system obey Vegard's law, a (A) = 5.4224 + 0.1208x. The obtained powders have good sinterability and the relative density could reach above 95% after being sintered at 1400 {sup o}C. Impedance spectroscopy measurements indicated that the conductivity of Ce{sub 0.8}Gd{sub 0.2-x}Nd{sub x}O{sub 2-{delta}} first increased and then decreased with Nd dopant content x. The maximum conductivity, {sigma}{sub 700{sup o}C} = 6.26 x 10{sup -2} S/cm, was found in Ce{sub 0.8}Gd{sub 0.12}Nd{sub 0.08}O{sub 1.9} when sintered at 1300 {sup o}C. The corresponding activation energies of conduction had a minimum value E{sub a} = 0.676 eV. The results tested experimentally the validity of the effective atomic number concept of recent density functional theory, which had suggested that co-dopant with effective atomic number between 61 (Pm) and 62 (Sm) was the ideal dopant exhibiting high ionic conductivity and low activation energy.

Yao, Hong-Chang, E-mail: yaohongchang@zzu.edu.cn [Department of Chemistry, Zhengzhou University, Zhengzhou 450052 (China)] [Department of Chemistry, Zhengzhou University, Zhengzhou 450052 (China); Zhang, Yu-Xin [Department of Chemistry, Zhengzhou University, Zhengzhou 450052 (China) [Department of Chemistry, Zhengzhou University, Zhengzhou 450052 (China); Henan Vocational College of Chemical Technology, Zhengzhou 450052 (China); Liu, Jia-Jia; Li, Yue-Li; Wang, Jian-She; Li, Zhong-Jun [Department of Chemistry, Zhengzhou University, Zhengzhou 450052 (China)] [Department of Chemistry, Zhengzhou University, Zhengzhou 450052 (China)

2011-01-15

266

Antioxidant status and Na(+), K (+)-ATPase activity in freshwater fish Carassius auratus exposed to different combustion products of Nafion 117 membrane: an integrated biomarker approach.  

PubMed

Nafion 117 membrane (N117), an important polymer electrolyte membrane (PEM), has been widely applied in numerous chemical technologies. Its increasing production and utilization will inevitably lead to the problem of waste disposal, with incineration as an important method. However, toxicity data of its combustion products on aquatic organisms have been seldom reported. The present study was therefore conducted to investigate the antioxidant response and Na(+), K(+)-ATPase activity in liver of Carassius auratus exposed to different combustion products of N117 for 5, 15, and 30 days. The concentrations of fluorine ion (F(-)) in the aquaria among the exposure durations were analyzed using the ion chromatography system. The results showed that these treatments have the capability to induce oxidative stress and suppress Na(+), K(+)-ATPase activity, as indicated by some significant alterations on these measured toxicity end-points in fish liver. According to the integrated biomarker response (IBR) index, the toxicity intensity of these experimental treatments was tentatively ranked. Taken together, these observations provided some preliminary data on the potential toxicity of the combustion products of N117 on aquatic organisms and could fill the information gaps in the toxicity database of the current-use PEM. PMID:25398218

Feng, Mingbao; Wang, Xinghao; Wang, Chao; Qin, Li; Wei, Zhongbo; Wang, Zunyao

2014-11-16

267

Combustion in fluidized beds  

SciTech Connect

Circulating fluidized-bed (CFB) combustion systems have become popular since the late 1970s, and, given the current level of activity in the area,it is clear that this technology has a stable future in the boiler market. For standard coal combustion applications, competition is fierce with mature pulverized-fuel-based (PF) technology set to maintain a strong profile. CFB systems, however, can be more cost effective than PF systems when emission control is considered, and, as CFB technology matures, it is expected that an ever-increasing proportion of boiler installations will utilize the CFB concept. CFB systems have advantages in the combustion of low-grade fuels such as coal waste and biomass. In competition with conventional bubbling beds, the CFB boiler often demonstrates superior carbon burn-out efficiency. The key to this combustion technique is the hydrodynamic behavior of the fluidized bed. This article begins with a description of the fundamental fluid dynamic behavior of the CFB system. This is followed by an examination of the combustion process in such an environment and a discussion of the current status of the major CFB technologies.

Dry, F.J.; La Nauze, R.D. (CSIRO, Div. of Mineral and Process Engineering, Clayton, Victoria 3168 (AU))

1990-07-01

268

Fluidized-bed combustion  

SciTech Connect

This report describes the activities of the Morgantown Energy Technology Center's research and development program in fluidized-bed combustion from October 1, 1987, to September 30, 1989. The Department of Energy program involves atmospheric and pressurized systems. Demonstrations of industrial-scale atmospheric systems are being completed, and smaller boilers are being explored. These systems include vortex, multi-solid, spouted, dual-sided, air-cooled, pulsed, and waste-fired fluidized-beds. Combustion of low-rank coal, components, and erosion are being studied. In pressurized combustion, first-generation, combined-cycle power plants are being tested, and second-generation, advanced-cycle systems are being designed and cost evaluated. Research in coal devolatilization, metal wastage, tube corrosion, and fluidization also supports this area. 52 refs., 24 figs., 3 tabs.

Botros, P E

1990-04-01

269

Thrombin-activated platelets promote leukotriene B4 synthesis in polymorphonuclear leucocytes stimulated by physiological agonists.  

PubMed Central

1. The addition of 2 x 10(8) human platelets to 8 x 10(6) polymorphonuclear leucocytes (PMNL) incubated in presence of 2.5 u ml-1 thrombin and 0.1 microM N-formyl-Met-Leu-Phe (FMLP) (or C5a or PAF) led to enhancement of leukotriene B4 (LTB4) synthesis by the PMNL (measured by h.p.l.c. as 20-hydroxy- and 20-carboxy-LTB4) from 4 +/- 1 pmol (in absence of platelets) to 26 +/- 4 pmol (mean +/- s.e.mean, n = 9). Platelets and thrombin were both essential for the enhancement of LTB4 synthesis. 2. Platelets also caused enhancement of LTB4 synthesis from (30 +/- 12 to 134 +/- 25 pmol, n = 6) when PMNL pretreated with granulocyte-macrophage colony-stimulating factor were used in similar experiments. 3. Enhancement of LTB4 synthesis was also observed (from 5 +/- 1.5 to 26.5 +/- 5 pmol, n = 9) when the supernatants of thrombin-activated platelet suspensions were added to FMLP-stimulated PMNL. 4. Supernatants of platelet suspensions activated by thrombin in presence of cyclo-oxygenase and 12-lipoxygenase inhibitors led to greater enhancement (from 5 +/- 3 to 153.5 +/- 27.5 pmol, n = 3) of LTB4 synthesis by FMLP-stimulated PMNL, suggesting that arachidonic acid itself, rather than its metabolites was responsible for the effects of platelets. 5. Addition of arachidonic acid to FMLP-stimulated PMNL at a concentration comparable to that measured in thrombin-activated platelet supernatants (0.2 +/- 0.025 microM, n = 6) mimicked the effect of platelets or platelet supernatants on LTB4 synthesis in FMLP-activated PMNL.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1655146

Palmantier, R.; Borgeat, P.

1991-01-01

270

Synthesis and sensory studies of umami-active scaffolds.  

PubMed

The class of 2-isopropyl-5-methylbicyclo[4.1.0]heptane-7-carboxamides, 1-4, has been identified as potent umami-tasting molecules. A scalable synthesis of this challenging scaffold and new sensory insights will be presented. Interestingly, the umami characteristics differ remarkably, depending on constitutional and stereochemical features of the parent scaffold. During our studies, we could identify the carboxamide moiety as a crucial factor to influence the umami intensity of these scaffolds. In addition, the configuration of the cyclopropyl moiety exerts some influence, whereas the absolute configuration of the menthyl scaffold, at least the tested D- and L-configuration, is less important. PMID:25408323

Backes, Michael; Paetz, Susanne; Vössing, Tobias; Ley, Jakob Peter

2014-11-01

271

Bubble Combustion  

NASA Technical Reports Server (NTRS)

A method of energy production that is capable of low pollutant emissions is fundamental to one of the four pillars of NASA s Aeronautics Blueprint: Revolutionary Vehicles. Bubble combustion, a new engine technology currently being developed at Glenn Research Center promises to provide low emissions combustion in support of NASA s vision under the Emissions Element because it generates power, while minimizing the production of carbon dioxide (CO2) and nitrous oxides (NOx), both known to be Greenhouse gases. and allows the use of alternative fuels such as corn oil, low-grade fuels, and even used motor oil. Bubble combustion is analogous to the inverse of spray combustion: the difference between bubble and spray combustion is that spray combustion is spraying a liquid in to a gas to form droplets, whereas bubble combustion involves injecting a gas into a liquid to form gaseous bubbles. In bubble combustion, the process for the ignition of the bubbles takes place on a time scale of less than a nanosecond and begins with acoustic waves perturbing each bubble. This perturbation causes the local pressure to drop below the vapor pressure of the liquid thus producing cavitation in which the bubble diameter grows, and upon reversal of the oscillating pressure field, the bubble then collapses rapidly with the aid of the high surface tension forces acting on the wall of the bubble. The rapid and violent collapse causes the temperatures inside the bubbles to soar as a result of adiabatic heating. As the temperatures rise, the gaseous contents of the bubble ignite with the bubble itself serving as its own combustion chamber. After ignition, this is the time in the bubble s life cycle where power is generated, and CO2, and NOx among other species, are produced. However, the pollutants CO2 and NOx are absorbed into the surrounding liquid. The importance of bubble combustion is that it generates power using a simple and compact device. We conducted a parametric study using CAVCHEM, a computational model developed at Glenn, that simulates the cavitational collapse of a single bubble in a liquid (water) and the subsequent combustion of the gaseous contents inside the bubble. The model solves the time-dependent, compressible Navier-Stokes equations in one-dimension with finite-rate chemical kinetics using the CHEMKIN package. Specifically, parameters such as frequency, pressure, bubble radius, and the equivalence ratio were varied while examining their effect on the maximum temperature, radius, and chemical species. These studies indicate that the radius of the bubble is perhaps the most critical parameter governing bubble combustion dynamics and its efficiency. Based on the results of the parametric studies, we plan on conducting experiments to study the effect of ultrasonic perturbations on the bubble generation process with respect to the bubble radius and size distribution.

Corrigan, Jackie

2004-01-01

272

Synthesis of Functionalized 4-Methylenetetrahydropyrans by Oxidative Activation of Cinnamyl or Benzyl Ethers  

PubMed Central

Oxidative activation of benzyl or cinnamyl ether bearing allylsilane derivatives using a catalytic amount of DDQ and 2 equivalents of CAN in the presence of PPTS provided functionalized 4-methylenetetrahydropyrans in good yields and excellent diastereoselectivity. The reaction could be applied to the synthesis of a variety of substituted tetrahydropyran derivatives. PMID:22773862

Cheng, Xu

2012-01-01

273

Recent advances on the green synthesis and antioxidant activities of pyrazoles.  

PubMed

Pyrazoles have a representative history in medicinal chemistry. These nucleuses, molecules of synthetic origin, constitute a group of nitrogen heterocyclic compounds. Available literature particularly shows a variety of pyrazoles with antioxidant effect. In this connection, this review describes the advances on the green synthesis of pyrazoles with antioxidant activity, mainly covering the data published over the last seven years (2008-2014). PMID:25553424

Dias, Daiane; Pacheco, Bruna S; Cunico, Wilson; Pizzuti, Lucas; Pereira, Claudio M P

2015-01-12

274

Synthesis and HDAC Inhibitory Activity of Isosteric Thiazoline-Oxazole Largazole Analogs  

PubMed Central

The synthesis of an isosteric analog of the natural product and HDAC inhibitor largazole is described. The sulfur atom in the thizaole ring of the natural product has been replaced with an oxygen atom, constituting an oxazole ring. The biochemical activity and cytotoxicity of this species is described. PMID:24035339

Guerra-Bubb, Jennifer M.; Bowers, Albert A.; Smith, William. B.; Paranal, Ronald; Estiu, Guillermina; Wiest, Olaf; Bradner, James E.; Williams, Robert M.

2013-01-01

275

Synthesis and HDAC inhibitory activity of isosteric thiazoline-oxazole largazole analogs.  

PubMed

The synthesis of an isosteric analog of the natural product and HDAC inhibitor largazole is described. The sulfur atom in the thizaole ring of the natural product has been replaced with an oxygen atom, constituting an oxazole ring. The biochemical activity and cytotoxicity of this species is described. PMID:24035339

Guerra-Bubb, Jennifer M; Bowers, Albert A; Smith, William B; Paranal, Ronald; Estiu, Guillermina; Wiest, Olaf; Bradner, James E; Williams, Robert M

2013-11-01

276

Synthesis of Ureido-Muraymycidine Derivatives for Structure Activity Relationship Studies of Muraymycins  

PubMed Central

One of the key constituents of the muraymycins is the 6-membered cyclic guanidine, (2S,3S)-muraymycidine (or epi-capreomycidine). In order to diversify the structure of the oligo-peptide moiety of the muraymycins for thorough structure activity relationship studies, we have developed a highly stereoselective synthesis of ureido-muraymycidine derivatives with the lactone 4a. PMID:22458337

Aleiwi, Bilal A.; Schneider, Christopher M.

2012-01-01

277

Synthesis, Characterization, and Activation of Zirconium and Hafnium Dialkyl Complexes that Contain a  

E-print Network

Synthesis, Characterization, and Activation of Zirconium and Hafnium Dialkyl Complexes that Contain of zirconium and hafnium complexes, [MepyN]MX2 (M ) Zr, X ) NMe2, Cl, OSO2CF3, CH2CHMe2, CH2Ph; M ) Hf, X ) NMe

Müller, Peter

278

Total Synthesis and Structure-Activity Relationship of Glycoglycerolipids from Marine Organisms  

PubMed Central

Glycoglycerolipids occur widely in natural products, especially in the marine species. Glycoglycerolipids have been shown to possess a variety of bioactivities. This paper will review the different methodologies and strategies for the synthesis of biological glycoglycerolipids and their analogs for bioactivity assay. In addition, the bioactivities and structure-activity relationship of the glycoglycerolipids are also briefly outlined. PMID:24945415

Zhang, Jun; Li, Chunxia; Yu, Guangli; Guan, Huashi

2014-01-01

279

One-Pot Synthesis of Protein-Embedded Metal-Organic Frameworks with Enhanced Biological Activities  

E-print Network

One-Pot Synthesis of Protein-Embedded Metal-Organic Frameworks with Enhanced Biological Activities Information ABSTRACT: Protein molecules were directly embedded in metal-organic frameworks (MOFs) by a coprecipitation method. The protein molecules majorly embedded on the surface region of MOFs display high

Zare, Richard N.

280

Synthesis and antitumor activity of 10-alkyl-10-deazaminopterins. A convenient synthesis of 10-deazaminopterin.  

PubMed

Requirements for large-scale synthesis of the potent antitumor drug 10-deazaminopterin have led to development of a facile synthesis of this compound and its 10-alkyl analogues. The lithium diisopropyl amide generated dianions of appropriate p-alkylbenzoic acids were alkylated with 3-methoxyallyl chloride. The resulting 4-(p-carboxyphenyl)-1-methoxy-1-butenes were brominated at pH 7-8 to afford the 2-bromo-4-(p-carboxyphenyl)butyraldehydes. Condensation with 2,4,5,6-tetraminopyrimidine and subsequent in situ oxidation of the resulting dihydropteridines yielded crystalline 10-alkyl-10-deaza-4-amino-4-deoxypteroic acids. The pteroic acids were coupled with diethyl glutamate via the mixed anhydride method, followed by saponification at room temperature, to give the target 10-deazaminopterins. The 10-alkyl compounds were approximately equipotent to 10-deazaminopterin as growth inhibitors of folate-dependent bacteria. Their abilities to inhibit Lactobacillus casei and L1210 derived dihydrofolate reductases were also similar. Transport properties in vitro were suggestive of an improved therapeutic index for the 10-alkyl analogues. Against L1210 in mice, the percent increase in life span at the LD10 dosage was +151% (methotrexate), +178% (10-deazaminopterin), +235% (10-methyl analogue), and +211% (10-ethyl analogue). 10,10-Dimethyl-10-deazaminopterin was less effective at an equimolar dosage, but the ILS at the maximum dose tested (72 mg/kg) was +135%. It was far less toxic than the other analogues possibly because of enhanced clearance. PMID:7143361

DeGraw, J I; Brown, V H; Tagawa, H; Kisliuk, R L; Gaumont, Y; Sirotnak, F M

1982-10-01

281

Bimetallic Fe-Ni Oxygen Carriers for Chemical Looping Combustion  

SciTech Connect

The relative abundance, low cost, and low toxicity of iron make Fe-based oxygen carriers of great interest for chemical looping combustion (CLC), an emerging technology for clean and efficient combustion of fossil and renewable fuels. However, Fe also shows much lower reactivity than other metals (such as Ni and Cu). Here, we demonstrate strong improvement of Fe-based carriers by alloying the metal phase with Ni. Through a combination of carrier synthesis and characterization with thermogravimetric and fixed-bed reactor studies, we demonstrate that the addition of Ni results in a significant enhancement in activity as well as an increase in selectivity for total oxidation. Furthermore, comparing alumina and ceria as support materials highlights the fact that reducible supports can result in a strong increase in oxygen carrier utilization.

Bhavsar, Saurabh; Veser, Goetz

2013-11-06

282

Ionic liquid self-combustion synthesis of BiOBr/Bi24O31Br10 heterojunctions with exceptional visible-light photocatalytic performances  

NASA Astrophysics Data System (ADS)

Heterostructured BiOBr/Bi24O31Br10 nanocomposites with surface oxygen vacancies are constructed by a facile in situ route of one-step self-combustion of ionic liquids. The compositions can be easily controlled by simply adjusting the fuel ratio of urea and 2-bromoethylamine hydrobromide (BTH). BTH serves not only as a fuel, but also as a complexing agent for ionic liquids and a reactant to supply the Br element. The heterojunctions show remarkable adsorptive ability for both the cationic dye of rhodamine B (RhB) and the anionic dye of methylene orange (MO) at high concentrations, which is attributed to the abundant surface oxygen vacancies. The sample containing 75.2% BiOBr and 24.8% Bi24O31Br10 exhibits the highest photocatalytic activity. Its reaction rate constant is 4.0 and 9.0 times that of pure BiOBr in degrading 50 mg L-1 of RhB and 30 mg L-1 of MO under visible-light (? > 400 nm) irradiation, respectively, which is attributed to the narrow band gap and highly efficient transfer efficiency of charge carriers. Different photocatalytic reaction processes and mechanisms over pure BiOBr and heterojunctions are proposed.Heterostructured BiOBr/Bi24O31Br10 nanocomposites with surface oxygen vacancies are constructed by a facile in situ route of one-step self-combustion of ionic liquids. The compositions can be easily controlled by simply adjusting the fuel ratio of urea and 2-bromoethylamine hydrobromide (BTH). BTH serves not only as a fuel, but also as a complexing agent for ionic liquids and a reactant to supply the Br element. The heterojunctions show remarkable adsorptive ability for both the cationic dye of rhodamine B (RhB) and the anionic dye of methylene orange (MO) at high concentrations, which is attributed to the abundant surface oxygen vacancies. The sample containing 75.2% BiOBr and 24.8% Bi24O31Br10 exhibits the highest photocatalytic activity. Its reaction rate constant is 4.0 and 9.0 times that of pure BiOBr in degrading 50 mg L-1 of RhB and 30 mg L-1 of MO under visible-light (? > 400 nm) irradiation, respectively, which is attributed to the narrow band gap and highly efficient transfer efficiency of charge carriers. Different photocatalytic reaction processes and mechanisms over pure BiOBr and heterojunctions are proposed. Electronic supplementary information (ESI) available: XRD pattern for composition calculation (Fig. S1), SEM photographs (Fig. S2), N2 absorption-desorption isotherms (Fig. S3), STEM images (Fig. S4), time-course variation of ln(C0/C) of dyes (Fig. S5), Appearance photographs for adsorption of dyes (Fig. S6), UV-Vis absorption spectra of NBT (Fig. S7), pseudo-first order rate constants for RhB and MO degradation (Tables S1 and S2), electronegativity, calculated CB and VB edge positions (Table S3). See DOI: 10.1039/c4nr05451b

Li, Fa-Tang; Wang, Qing; Ran, Jingrun; Hao, Ying-Juan; Wang, Xiao-Jing; Zhao, Dishun; Qiao, Shi Zhang

2014-12-01

283

Partners in crime: deregulation of AR activity and androgen synthesis in prostate cancer  

PubMed Central

Prostate cancer remains a leading cause of cancer death, as there are no durable means to treat advanced disease. Treatment of non-organ confined prostate cancer hinges on its androgen dependence. First line therapeutic strategies suppress androgen receptor (AR) activity, via androgen ablation and direct AR antagonists. While initially effective, incurable, "castration-resistant" tumors arise due to resurgent AR activity. Alterations of AR and/or associated regulatory networks are known to restore receptor activity and support resultant therapy-resistant tumor progression. However, recent evidence also reveals an unexpected contribution of AR ligand, wherein alterations in pathways controlling androgen synthesis support castrate-resistant AR activity. Herein, mechanisms underlying the lethal pairing of AR deregulation and aberrant androgen synthesis in prostate cancer progression will be discussed. PMID:20138542

Knudsen, Karen E.; Penning, Trevor

2010-01-01

284

Intracellular synthesis of silver nanoparticle by actinobacteria and its antimicrobial activity.  

PubMed

Intracellular synthesis of silver nanoparticles (AgNPs) using Rhodococcus spp. is demonstrated. The synthesized nanoparticles were characterized by UV-Vis spectroscopy, X-ray diffraction, energy dispersive spectroscopy, Fourier trans-form infrared spectroscopy, and transmission electron microscopy. Transmission electron microscopy study of microorganisms' revealed synthesis of nanoparticle was occurring inside the cell, in the cytoplasm. AgNPs ranged from 5 to 50nm. Formed nanoparticles were stable in the colloidal solution due to presence of proteins on the surface. AgNPs showed excellent bactericidal and bacteriostatic activity against pathogenic microorganisms. PMID:25456659

Otari, S V; Patil, R M; Ghosh, S J; Thorat, N D; Pawar, S H

2015-02-01

285

Intracellular synthesis of silver nanoparticle by actinobacteria and its antimicrobial activity  

NASA Astrophysics Data System (ADS)

Intracellular synthesis of silver nanoparticles (AgNPs) using Rhodococcus spp. is demonstrated. The synthesized nanoparticles were characterized by UV-Vis spectroscopy, X-ray diffraction, energy dispersive spectroscopy, Fourier trans-form infrared spectroscopy, and transmission electron microscopy. Transmission electron microscopy study of microorganisms' revealed synthesis of nanoparticle was occurring inside the cell, in the cytoplasm. AgNPs ranged from 5 to 50 nm. Formed nanoparticles were stable in the colloidal solution due to presence of proteins on the surface. AgNPs showed excellent bactericidal and bacteriostatic activity against pathogenic microorganisms.

Otari, S. V.; Patil, R. M.; Ghosh, S. J.; Thorat, N. D.; Pawar, S. H.

2015-02-01

286

Concise synthesis of (-)-steviamine and analogues and their glycosidase inhibitory activities.  

PubMed

A concise synthesis of (-)-steviamine is reported along with the synthesis of its analogues 10-nor-steviamine, 10-nor-ent-steviamine and 5-epi-ent-steviamine. These compounds were tested against twelve glycosidases (at 143 ?g mL(-1) concentrations) and were found to have in general poor inhibitory activity against most enzymes. The 10-nor analogues however, showed 50-54% inhibition of ?-L-rhamnosidase from Penicillium decumbens while one of these, 10-nor-steviamine, showed 51% inhibition of N-acetyl-?-D-glucosaminidase (from Jack bean) at the same concentration (760 ?M). PMID:23640519

Jiangseubchatveera, Nadechanok; Bouillon, Marc E; Liawruangrath, Boonsom; Liawruangrath, Saisunee; Nash, Robert J; Pyne, Stephen G

2013-06-21

287

Smoldering Combustion Experiments in Microgravity  

NASA Technical Reports Server (NTRS)

The Microgravity Smoldering Combustion (MSC) experiment is part of a study of the smolder characteristics of porous combustible materials in a microgravity environment. Smoldering is a non-flaming form of combustion that takes place in the interior of porous materials and takes place in a number of processes ranging from smoldering of porous insulation materials to high temperature synthesis of metals. The objective of the study is to provide a better understanding of the controlling mechanisms of smolder, both in microgravity and normal-gravity. As with many forms of combustion, gravity affects the availability of oxidizer and transport of heat, and therefore the rate of combustion. Microgravity smolder experiments, in both a quiescent oxidizing environment, and in a forced oxidizing flow have been conducted aboard the NASA Space Shuttle (STS-69 and STS-77 missions) to determine the effect of the ambient oxygen concentration and oxidizer forced flow velocity on smolder combustion in microgravity. The experimental apparatus is contained within the NASA Get Away Special Canister (GAS-CAN) Payload. These two sets of experiments investigate the propagation of smolder along the polyurethane foam sample under both diffusion driven and forced flow driven smoldering. The results of the microgravity experiments are compared with identical ones carried out in normal gravity, and are used to verify present theories of smolder combustion. The results of this study will provide new insights into the smoldering combustion process. Thermocouple histories show that the microgravity smolder reaction temperatures (Ts) and propagation velocities (Us) lie between those of identical normal-gravity upward and downward tests. These observations indicate the effect of buoyancy on the transport of oxidizer to the reaction front.

Walther, David C.; Fernandez-Pello, A. Carlos; Urban, David L.

1997-01-01

288

Combustion & Health  

E-print Network

FFCOMBUSTION & HEALTH Winifred J. Hamilton, PhD, SM Clear Air Through Energy Efficiency (CATEE) Galveston, TX October 9?11, 2012 FFCOMBUSTION & HEALTH FFCOMBUSTION: THE THREAT ? Biggest threat to world ecosystems (and to human health...) ? Combustion of fossil fuels for ? Electricity ? Industrial processes ? Vehicle propulsion ? Cooking and heat ? Other ? Munitions ? Fireworks ? Light ? Cigarettes, hookahs? FFCOMBUSTION & HEALTH FFCOMBUSTION: THE THREAT ? SCALE (think health...

Hamilton, W.

2012-01-01

289

Study of the kinetic parameters for synthesis and hydrolysis of pharmacologically active salicin isomer catalyzed by baker's yeast maltase  

NASA Astrophysics Data System (ADS)

One of the key elements for understanding enzyme reactions is determination of its kinetic parameters. Since transglucosylation is kinetically controlled reaction, besides the reaction of synthesis, very important is the reaction of enzymatic hydrolysis of created product. Therefore, in this study, kinetic parameters for synthesis and secondary hydrolysis of pharmacologically active ? isosalicin by baker's yeast maltase were calculated, and it was shown that specifity of maltase for hydrolysis is approximately 150 times higher then for synthesis.

Veli?kovi?, D. V.; Dimitrijevi?, A. S.; Bihelovi?, F. J.; Jankov, R. M.; Milosavi?, N.

2011-12-01

290

DNase 1 retains endodeoxyribonuclease activity following gold nanocluster synthesis.  

PubMed

Here we present the synthesis of the enzyme DNase 1 stabilized gold nanoclusters (DNase 1:AuNCs) with core size consisting of either 8 or 25 atoms. The DNase 1:Au8NCs exhibit blue fluorescence whereas the DNase 1:Au25NCs are red emitting. In addition to the intense fluorescence emission, the synthesized DNase 1:AuNC hybrid retains the native functionality of the protein, allowing simultaneous detection and digestion of DNA with a detection limit of 2 ?g/mL. The DNase 1:AuNCs could be conveniently employed as efficient and fast sensors to augment the current time-consuming DNA contamination analysis techniques. PMID:24999001

West, Abby L; Griep, Mark H; Cole, Daniel P; Karna, Shashi P

2014-08-01

291

Approaches to the Synthesis of a Novel, anti-HIV Active Integrase Inhibitor  

PubMed Central

The novel HIV-1 integrase inhibitor 1, discovered in our laboratory, exhibits potent anti-HIV activity against a diverse set of HIV-1 isolates and also against HIV-2 and SIV. In addition, this compound displays low cellular cytotoxicity and possesses a favorable in vitro drug interaction profile with respect to isozymes of cytochrome P450 (CYP) and uridine 5'-diphospho-glucuronosyltransferase (UGT). However, the total synthesis of this significant HIV integrase inhibitor has not been reported. This contribution describes an optimized, reproducible, multi-step, synthetic route to inhibitor 1. The yield for the separate steps averaged about 80%. The methodologies utilized in the synthesis were, among others, a palladium-catalyzed cross-coupling reaction, a crossed-Claisen condensation, and a hydrazino amide synthesis step. Successful alternative synthetic methodologies for some of the steps are also described. PMID:24100441

Okello, Maurice; Nishonov, Malik; Singh, Pankaj; Mishra, Sanjay; Mangu, Naveen; Seo, Byung; Gund, Machhindra; Nair, Vasu

2013-01-01

292

Activation of Aluminum as an Effective Reducing Agent by Pitting Corrosion for Wet-chemical Synthesis  

PubMed Central

Metallic aluminum (Al) is of interest as a reducing agent because of its low standard reduction potential. However, its surface is invariably covered with a dense aluminum oxide film, which prevents its effective use as a reducing agent in wet-chemical synthesis. Pitting corrosion, known as an undesired reaction destroying Al and is enhanced by anions such as F?, Cl?, and Br? in aqueous solutions, is applied here for the first time to activate Al as a reducing agent for wet-chemical synthesis of a diverse array of metals and alloys. Specifically, we demonstrate the synthesis of highly dispersed palladium nanoparticles on carbon black with stabilizers and the intermetallic Cu2Sb/C, which are promising candidates, respectively, for fuel cell catalysts and lithium-ion battery anodes. Atomic hydrogen, an intermediate during the pitting corrosion of Al in protonic solvents (e.g., water and ethylene glycol), is validated as the actual reducing agent. PMID:23390579

Li, Wei; Cochell, Thomas; Manthiram, Arumugam

2013-01-01

293

Combustion synthesis and luminescent properties of green-emitting phosphor (Sr, Zn) Al 2 O 4 : Eu 2+ , B 3+ for white light emitting diodes (WLED)  

Microsoft Academic Search

In this study, the phosphors (Sr1?x\\u000a , Zn\\u000a x\\u000a )0.9(Al2?y\\u000a , B\\u000a y\\u000a )O4 doped 10 mol % Eu2+, were prepared by combustion method as the fluorescent material for white light emitting diodes (WLEDs), performing as a\\u000a light source. The luminescent properties were investigated by changing the combustion temperature, the boron concentration,\\u000a and the ratio of Sr to Zn. The

Shan-Shan Yao; Yuan-Yuan Li; Dong-Hua Chen; Wan-Jun Tang; Yu-Hua Peng

2009-01-01

294

Combustion 2000  

SciTech Connect

This report presents work carried out under contract DE-AC22-95PC95144 ''Combustion 2000 - Phase II.'' The goals of the program are to develop a coal-fired high performance power generation system (HIPPS) that is capable of: {lg_bullet} thermal efficiency (HHV) {ge} 47% {lg_bullet} NOx, SOx, and particulates {le} 10% NSPS (New Source Performance Standard) {lg_bullet} coal providing {ge} 65% of heat input {lg_bullet} all solid wastes benign {lg_bullet} cost of electricity {le} 90% of present plants Phase I, which began in 1992, focused on the analysis of various configurations of indirectly fired cycles and on technical assessments of alternative plant subsystems and components, including performance requirements, developmental status, design options, complexity and reliability, and capital and operating costs. Phase I also included preliminary R&D and the preparation of designs for HIPPS commercial plants approximately 300 MWe in size. Phase II, had as its initial objective the development of a complete design base for the construction and operation of a HIPPS prototype plant to be constructed in Phase III. As part of a descoping initiative, the Phase III program has been eliminated and work related to the commercial plant design has been ended. The rescoped program retained a program of engineering research and development focusing on high temperature heat exchangers, e.g. HITAF development (Task 2); a rescoped Task 6 that is pertinent to Vision 21 objectives and focuses on advanced cycle analysis and optimization, integration of gas turbines into complex cycles, and repowering designs; and preparation of the Phase II Technical Report (Task 8). This rescoped program deleted all subsystem testing (Tasks 3, 4, and 5) and the development of a site-specific engineering design and test plan for the HIPPS prototype plant (Task 7). Work reported herein is from: {lg_bullet} Task 2.2.4 Pilot Scale Testing {lg_bullet} Task 2.2.5.2 Laboratory and Bench Scale Activities

None

1999-12-31

295

Activity-Dependent Rapid Local RhoA Synthesis Is Required for Hippocampal Synaptic Plasticity.  

PubMed

Dendritic protein synthesis and actin cytoskeleton reorganization are important events required for the consolidation of hippocampal LTP and memory. However, the temporal and spatial relationships between these two processes remain unclear. Here, we report that treatment of adult rat hippocampal slices with BDNF or with tetraethylammonium (TEA), which induces a chemical form of LTP, produces a rapid and transient increase in RhoA protein levels. Changes in RhoA were restricted to dendritic spines of CA3 and CA1 and require de novo protein synthesis regulated by mammalian target of rapamycin (mTOR). BDNF-mediated stimulation of RhoA activity, cofilin phosphorylation, and actin polymerization were completely suppressed by protein synthesis inhibitors. Furthermore, intrahippocampal injections of RhoA antisense oligodeoxynucleotides inhibited theta burst stimulation (TBS)-induced RhoA upregulation in dendritic spines and prevented LTP consolidation. Addition of calpain inhibitors after BDNF or TEA treatment maintained RhoA levels elevated and prolonged the effects of BDNF and TEA on actin polymerization. Finally, the use of isoform-selective calpain inhibitors revealed that calpain-2 was involved in RhoA synthesis, whereas calpain-1 mediated RhoA degradation. Overall, this mechanism provides a novel link between dendritic protein synthesis and reorganization of the actin cytoskeleton in hippocampal dendritic spines during LTP consolidation. PMID:25653381

Briz, Victor; Zhu, Guoqi; Wang, Yubin; Liu, Yan; Avetisyan, Mariam; Bi, Xiaoning; Baudry, Michel

2015-02-01

296

Syndecan-2 regulates melanin synthesis via protein kinase C ?II-mediated tyrosinase activation.  

PubMed

Syndecan-2, a transmembrane heparan sulfate proteoglycan that is highly expressed in melanoma cells, regulates melanoma cell functions (e.g. migration). Since melanoma is a malignant tumor of melanocytes, which largely function to synthesize melanin, we investigated the possible involvement of syndecan-2 in melanogenesis. Syndecan-2 expression was increased in human skin melanoma tissues compared with normal skin. In both mouse and human melanoma cells, siRNA-mediated knockdown of syndecan-2 was associated with reduced melanin synthesis, whereas overexpression of syndecan-2 increased melanin synthesis. Similar effects were also detected in human primary epidermal melanocytes. Syndecan-2 expression did not affect the expression of tyrosinase, a key enzyme in melanin synthesis, but instead enhanced the enzymatic activity of tyrosinase by increasing the membrane and melanosome localization of its regulator, protein kinase C?II. Furthermore, UVB caused increased syndecan-2 expression, and this up-regulation of syndecan-2 was required for UVB-induced melanin synthesis. Taken together, these data suggest that syndecan-2 regulates melanin synthesis and could be a potential therapeutic target for treating melanin-associated diseases. PMID:24472179

Jung, Hyejung; Chung, Heesung; Chang, Sung Eun; Choi, Sora; Han, Inn-Oc; Kang, Duk-Hee; Oh, Eok-Soo

2014-05-01

297

Peroxidase synthesis and activity in the interaction of soybean with Phytophthora megasperma f. sp. glycinea (Pmg)  

SciTech Connect

Changes, in peroxidase (EC1.11.1.7) have been reported following infection. However, determinations of biosynthesis of quantities of the peroxidase protein molecule have not been madeexclamation In this study hypocotyl of soybean seedlings (Glycine max; cv Harosoy, susceptible; cv Harosoy 63, resistant) were inoculated with zoospores of Pmg. Incorporation of /sup 35/S-methionine (supplied with inoculum) in TCA precipitates was measured. Peroxidase synthesis was measured by immuno precipitation using antibodies against a cationic and an anionic peroxidase derived from peanut cells. Specific peroxidase activity increased rapidly from 5 to 9 h following infection in the resistant reaction but not in the susceptible reaction or the water controls. There was increased synthesis of the anionic peroxidase but not of the cationic peroxidase in the resistant reaction. The anionic peroxidase did not increase in the susceptible until 15 h. The ratio of peroxidase synthesis to total protein synthesis decreased in inoculated tissues compared to control. Peroxidase synthesis is, therefore, a relative minor host response to infection.

Chibbar, R.N.; Esnault, R.; Lee, D.; van Huystee, R.B.; Ward, E.W.B.

1986-04-01

298

Synthesis and biological activity of Citridone A and its derivatives.  

PubMed

Citridone A (1), originally isolated as a potentiator of antifungal miconazole activity from a fungal culture broth, has a phenyl-R-furopyridone structure. Because of its unique ring structure, 11 derivatives were chemically synthesized and their biological activity was evaluated. Derivatives 17, 20 and 21 potentiated miconazole activity against Candida albicans. Furthermore, 1, 14, 20 and 21 were found to inhibit yellow pigment production in methicillin-resistant Staphylococcus aureus. PMID:24643052

Fukuda, Takashi; Shimoyama, Kenta; Nagamitsu, Tohru; Tomoda, Hiroshi

2014-06-01

299

Synthesis and characterization of inorganic polymers from the alkali activation of an aluminosilicate  

NASA Astrophysics Data System (ADS)

This paper presents the results of the synthesis and characterization of inorganic polymers (IP) from aluminosilicates: bentonite (BT) and pumice (PP). The synthesis of IP, was carried out by two methods involving alkaline activation, at room temperature and 80 ± 5 °C, using as activating agent sodium silicate both commercial and analytical (Na2SiO3). Sodium hydroxide (NaOH) at 3 M, 7 M and 12 M was added. A lower degree of polymerization was obtained by using analytical precursors subjected to room temperature and 80 ± 5°C. Replacement of heating by the use of the commercial activating agent with greater alkalinity allows the formation of a 3D network. The materials were structurally characterized by FTIR spectroscopy with Attenuated Reflectance (ATR), Scanning Electron Microscope (SEM) and X -ray diffraction (DRX).

González, C. P.; Montaño, A. M.; González, A. K.; Ríos, C. A.

2014-06-01

300

Lipase immobilized catalytically active membrane for synthesis of lauryl stearate in a pervaporation membrane reactor.  

PubMed

A composite catalytically active membrane immobilized with Candida rugosa lipase has been prepared by immersion phase inversion technique for enzymatic synthesis of lauryl stearate in a pervaporation membrane reactor. SEM images showed that a "sandwich-like" membrane structure with a porous lipase-PVA catalytic layer uniformly coated on a polyvinyl alcohol (PVA)/polyethersulfone (PES) bilayer was obtained. Optimum conditions for lipase immobilization in the catalytic layer were determined. The membrane was proved to exhibit superior thermal stability, pH stability and reusability than free lipase under similar conditions. In the case of pervaporation coupled synthesis of lauryl stearate, benefited from in-situ water removal by the membrane, a conversion enhancement of approximately 40% was achieved in comparison to the equilibrium conversion obtained in batch reactors. In addition to conversion enhancement, it was also found that excess water removal by the catalytically active membrane appears to improve activity of the lipase immobilized. PMID:25218626

Zhang, Weidong; Qing, Weihua; Ren, Zhongqi; Li, Wei; Chen, Jiangrong

2014-11-01

301

Akt activation enhances ribosomal RNA synthesis through casein kinase II and TIF-IA  

PubMed Central

Transcription initiation factor I (TIF-IA) plays an essential role in regulating ribosomal RNA (rRNA) synthesis by tethering RNA polymerase I (Pol I) to the rDNA promoter. We have found that activated Akt enhances rRNA synthesis through the phosphorylation of casein kinase II? (CK2?) on a threonine residue near its N terminus. CK2 in turn phosphorylates TIF-IA, thereby increasing rDNA transcription. Activated Akt also stabilizes TIF-IA, induces its translocation to the nucleolus, and enhances its interaction with Pol I. Treatment with AZD8055, an inhibitor of both Akt and mammalian target of rapamycin phosphorylation, but not with rapamycin, disrupts Akt-mediated TIF-IA stability, translocation, and activity. These data support a model in which activated Akt enhances rRNA synthesis both by preventing TIF-IA degradation and phosphorylating CK2?, which in turn phosphorylates TIF-IA. This model provides an explanation for the ability of activated Akt to promote cell proliferation and, potentially, transformation. PMID:24297901

Nguyen, Le Xuan Truong; Mitchell, Beverly S.

2013-01-01

302

Synthesis and biological activity of n-butylphthalide derivatives.  

PubMed

A series of n-butylphthalide derivatives were designed and synthesized. The in vitro activities of these compounds were evaluated by a resting tension of isolated rat thoracic aorta ring assay. Compounds 4g and 4i were found to be more active than n-butylphthalide. PMID:20133025

Wang, Wei; Cha, Xue-Xiang; Reiner, John; Gao, Yuan; Qiao, Hai-Ling; Shen, Jia-Xiang; Chang, Jun-Biao

2010-05-01

303

Immobilization of lysozyme on cotton fabrics; synthesis, characterication, and activity  

Technology Transfer Automated Retrieval System (TEKTRAN)

The antimicrobial activity of lysozyme derives from the hydrolysis of the bacterial cell wall polysaccharide at the glycosidic bond that links N-acetyl-glucosamine and N-acetyl-muramic acid. Maintaining the activity of lysozyme while bound to a cellulose substrate is a goal toward developing enzyme...

304

Geopolymer synthesis using alkaline activation of natural zeolite  

Microsoft Academic Search

The influence of activator ratio, time, and curing temperature on the mechanical strength of geopolymers synthesized from natural zeolite was evaluated by employing silicate solutions and sodium hydroxide. The results demonstrated that an increase in the activator ratio as well as that of curing time favors mechanical strength in the material. Nevertheless, with 90day of curing time and 80°C or

C. Villa; E. T. Pecina; R. Torres; L. Gómez

2010-01-01

305

Synthesis and fungicidal activity of 2,2?-bipyridine derivatives  

Microsoft Academic Search

A series of substituted 2,2?-bipyridine derivatives was prepared using the Kröhnke reaction and alkylation of 4,4?-dimethyl-2,2?-bipyridine. These compounds were screened for fungicidal activity against 9 plant diseases. 5-Phenyl-2,2?-bipyridine exhibited strong preventative and curative fungicidal activity against wheat powdery mildew (Erisyphe graminis) and wheat leaf rust (Puccinia recondita).

Bernadette M. Kelly-Basetti; Darren J. Cundy; Suzanne M. Pereira; Wolfgang H. F. Sasse; G. Paul Savage; Gregory W. Simpson

1995-01-01

306

Signaling Logic of Activity-Triggered Dendritic Protein Synthesis: An mTOR Gate But Not a Feedback Switch  

Microsoft Academic Search

Changes in synaptic efficacy are believed to form the cellular basis for memory. Protein synthesis in dendrites is needed to consolidate long-term synaptic changes. Many signals converge to regulate dendritic protein synthesis, including synaptic and cellular activity, and growth factors. The coordination of these multiple inputs is especially intriguing because the synthetic and control pathways themselves are among the synthesized

Pragati Jain; Upinder S. Bhalla

2009-01-01

307

Design, Synthesis and Antiviral Activity Studies of Schizonepetin Derivatives  

PubMed Central

A series of schizonepetin derivatives have been designed and synthesized in order to obtain potent antivirus agents. The antiviral activity against HSV-1 and influenza virus H3N2 as well as the cytotoxicity of these derivatives was evaluated by using cytopathic effect (CPE) inhibition assay in vitro. Compounds M2, M4, M5 and M34 showed higher inhibitory activity against HSV-1 virus with the TC50 values being in micromole. Compounds M28, M33, and M35 showed higher inhibitory activity against influenza virus H3N2 with their TC50 values being 96.4, 71.0 and 75.4 ?M, respectively. Preliminary biological activity evaluation indicated that the anti-H3N2 and anti-HSV-1 activities improved obviously through the introduction of halogen into the structure of schizonepetin. PMID:23965980

Bao, Beihua; Meng, Zheng; Li, Nianguang; Meng, Zhengjie; Zhang, Li; Cao, Yudan; Yao, Weifeng; Shan, Mingqiu; Ding, Anwei

2013-01-01

308

Synthesis of 2-methoxybenzoylhydrazone and evaluation of their antileishmanial activity.  

PubMed

Compounds 1-25 showed varying degree of antileishmanial activities with IC50 values ranging between 1.95 and 88.56 ?M. Compounds 2, 10, and 11 (IC50=3.29±0.07 ?M, 1.95±0.04 ?M, and 2.49±0.03 ?M, respectively) were found to be more active than standard pentamidine (IC50=5.09±0.04 ?M). Compounds 7 (IC50=7.64±0.1 ?M), 8 (IC50=13.17±0.46 ?M), 18 (IC50=13.15±0.02 ?M), and 24 (IC50=15.65±0.41 ?M) exhibited good activities. Compounds 1, 3, 4, 5, 9, 12, 15, 18, and 19 were found to be moderately active. Compounds 13, 14, 16, 17, 20-25 showed weak activities with IC50 values ranging between 57 and 88 ?M. PMID:23608761

Taha, Muhammad; Baharudin, Mohd Syukri; Ismail, Nor Hadiani; Khan, Khalid Mohammed; Jaafar, Faridahanim Mohd; Samreen; Siddiqui, Salman; Choudhary, M Iqbal

2013-06-01

309

Dihydroasparagusic acid: antioxidant and tyrosinase inhibitory activities and improved synthesis.  

PubMed

Dihydroasparagusic acid (DHAA) is the reduced form of asparagusic acid, a sulfur-containing flavor component produced by Asparagus plants. In this work, DHAA was synthetically produced by modifying some published protocols, and the synthesized molecule was tested in several in vitro assays (DPPH, ABTS, FRAP-ferrozine, BCB, deoxyribose assays) to evaluate its radical scavenging activity. Results show that DHAA is endowed with a significant in vitro antioxidant activity, comparable to that of Trolox. DHAA was also evaluated for its inhibitory activity toward tyrosinase, an enzyme involved, among others, in melanogenesis and in browning processes of plant-derived foods. DHAA was shown to exert an inhibitory effect on tyrosinase activity, and the inhibitor kinetics, analyzed by a Lineweaver-Burk plot, exhibited a competitive mechanism. Taken together, these results suggest that DHAA may be considered as a potentially active molecule for use in various fields of application, such as pharmaceutical, cosmetics, agronomic and food. PMID:23790134

Venditti, Alessandro; Mandrone, Manuela; Serrilli, Anna Maria; Bianco, Armandodoriano; Iannello, Carmelina; Poli, Ferruccio; Antognoni, Fabiana

2013-07-17

310

Synthesis and anticancer activity of quinopimaric and maleopimaric acids' derivatives.  

PubMed

A series of quinopimaric and maleopimaric acids' derivatives modified in the E-ring, at the carbonyl- and carboxyl-groups were synthesized and their in vitro cytotoxic activity was evaluated at the National Cancer Institute, USA. Methyl esters of dihydroquinopimaric, 1a,4a-dehydroquinopimaric, 2,3-epoxyquinopimaric, 1-ethylenketal-dihydroquinopimaric, 1-ethylenketal-4-hydroxyiminodihydroquinopimaric acids displayed an activity on renal cancer, leukemia, colon cancer and breast cancer cell lines in concentration 10(-5)M. Methyl 1,4-dihydroxyiminodihydroquinopimarate showed both a potent and broad spectrum of cytotoxic activity against NSC lung cancer, colon cancer, breast cancer, renal cancer and leukemia and revealed in vivo antineoplastic activity towards mouse solid transplantable mammary carcinoma Ca755 and colon adenocarcinoma AKATOL. The information about antineoplastic activity of the studied quinopimaric and maleopimaric acids' derivatives will be used for hit to lead optimization in these chemical series. PMID:25440729

Tretyakova, Elena V; Smirnova, Irina E; Kazakova, Oxana B; Tolstikov, Genrikh A; Yavorskaya, Nadejda P; Golubeva, Irina S; Pugacheva, Rujena B; Apryshko, Galina N; Poroikov, Vladimir V

2014-09-20

311

Synthesis, magnetic properties and catalytic activity of hierarchical cobalt microflowers.  

PubMed

A simple one pot synthesis method for the silver catalyzed growth of pure hexagonal close packed cobalt by the reduction of cobalt salt using hydrazine hydrate in the presence of triethanolamine (TEA), diethanolamine (DEA) and ethylene glycol (EG) as capping agents at 90 degrees C within 10 min has been reported. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images of the product prepared in the presence of capping agents show the formation of the well defined porous flowery architecture originating from the interlinked 2D wavy nanoflakes. When the same reaction is performed in the absence of any capping agent, the agglomeration of the flakes of cobalt with irregular spherical morphology is observed. The effect of the reaction conditions on the size and the shape of the products have also been studied. Vibration sample magnetometer (VSM) shows, that the products are ferromagnetic in nature irrespective of the capping agents used and possess high value of coercivity, when prepared in the absence of any capping agent. These cobalt microflowers have also been proved as an alternative to the other available expensive catalysts (Au, Ag, Pt) in the room temperature production of p-aminophenol for its applications in pharmaceutical, photographic and plastic industries. PMID:22849064

Senapati, Samarpita; Srivastava, Suneel Kumar; Singh, Shiv Brat

2012-04-01

312

Ribosome Synthesis and MAPK Activity Modulate Ionizing Radiation-Induced Germ Cell Apoptosis in Caenorhabditis elegans  

PubMed Central

Synthesis of ribosomal RNA by RNA polymerase I (RNA pol I) is an elemental biological process and is key for cellular homeostasis. In a forward genetic screen in C. elegans designed to identify DNA damage-response factors, we isolated a point mutation of RNA pol I, rpoa-2(op259), that leads to altered rRNA synthesis and a concomitant resistance to ionizing radiation (IR)-induced germ cell apoptosis. This weak apoptotic IR response could be phenocopied when interfering with other factors of ribosome synthesis. Surprisingly, despite their resistance to DNA damage, rpoa-2(op259) mutants present a normal CEP-1/p53 response to IR and increased basal CEP-1 activity under normal growth conditions. In parallel, rpoa-2(op259) leads to reduced Ras/MAPK pathway activity, which is required for germ cell progression and physiological germ cell death. Ras/MAPK gain-of-function conditions could rescue the IR response defect in rpoa-2(op259), pointing to a function for Ras/MAPK in modulating DNA damage-induced apoptosis downstream of CEP-1. Our data demonstrate that a single point mutation in an RNA pol I subunit can interfere with multiple key signalling pathways. Ribosome synthesis and growth-factor signalling are perturbed in many cancer cells; such an interplay between basic cellular processes and signalling might be critical for how tumours evolve or respond to treatment. PMID:24278030

Eberhard, Ralf; Stergiou, Lilli; Hofmann, E. Randal; Hofmann, Jen; Haenni, Simon; Teo, Youjin; Furger, André; Hengartner, Michael O.

2013-01-01

313

Synthesis and antimicrobial activity of cysteine-free coprisin nonapeptides.  

PubMed

Coprisin is a 43-mer defensin-like peptide from the dung beetle, Copris tripartitus. CopA3 (LLCIALRKK-NH?), a 9-mer peptide containing a single free cysteine residue at position 3 of its sequence, was derived from the ?-helical region of coprisin and exhibits potent antibacterial and anti-inflammatory activities. The single cysteine implies a tendency for dimerization; however, it remains unknown whether this cysteine residue is indispensible for CopA3's antimicrobial activity. To address this issue, in the present study we synthesized eight cysteine-substituted monomeric CopA3 analogs and two dimeric analogs, CopA3 (Dimer) and CopIK (Dimer), and evaluated their antimicrobial effects against bacteria and fungi, as well as their hemolytic activity toward human erythrocytes. Under physiological conditions, CopA3 (Mono) exhibits a 6/4 (monomer/dimer) molar ratio in HPLC area percent, indicating that its effects on bacterial strains likely reflect a CopA3 (Mono)/CopA3 (Dimer) mixture. We also report the identification of CopW, a new cysteine-free nonapeptide derived from CopA3 that has potent antimicrobial activity with virtually no hemolytic activity. Apparently, the cysteine residue in CopA3 is not essential for its antimicrobial function. Notably, CopW also exhibited significant synergistic activity with ampicillin and showed more potent antifungal activity than either wild-type coprisin or melittin. PMID:24321546

Lee, Jaeho; Lee, Daeun; Choi, Hyemin; Kim, Ha Hyung; Kim, Ho; Hwang, Jae Sam; Lee, Dong Gun; Kim, Jae Il

2014-01-10

314

Design, synthesis and antimycobacterial activity evaluation of natural oridonin derivatives.  

PubMed

In an effort to develop novel potent antitubercular drugs, thirty-one oridonin derivatives were designed and prepared. All the compounds obtained were screened for their in vitro activities against Mycobacterium phlei, Mycobacterium smegmatis and Mycobacterium marinum. Among them, thirteen compounds showed significant inhibitory activity against M. phlei with MICs less than 2 ?g/mL. Compounds 2k, 8d, 10c, 10d containing trans-cinnamic acid moiety were the most potent (MIC=0.5 ?g/mL), comparable to the well-known antitubercular drug streptomycin. The preliminary structure-activity relationships (SARs) were also analyzed. PMID:24835198

Xu, Shengtao; Li, Dahong; Pei, Lingling; Yao, Hong; Wang, Chengqian; Cai, Hao; Yao, Hequan; Wu, Xiaoming; Xu, Jinyi

2014-07-01

315

Synthesis and evaluation of dioleoyl glyceric acids showing antitrypsin activity.  

PubMed

Previously, Lešová et al. reported the isolation and identification of metabolite OR-1, showing antitrypsin activity, produced during fermentation by Penicillium funiculosum. The structure of OR-1 was a mixture of glyceric acid (GA), esterified with C(14)-C(18) fatty acids, and oleic acid (C18:1) as the most predominant fatty acid (Folia Microbiol. 46, 21-23, 2001). In this study, dioleoyl D-GA and dioleoyl L-GA were synthesized via diesterification with oleoyl chloride, and their antitrypsin activities were evaluated using both a disk diffusion method and spectral absorption measurements. The results show that both compounds and their equivalent mixtures possess antitrypsin activities; however, their IC(50) values (approximately 2 mM) are much higher than that of OR-1 (4.25 µM), suggesting that dioleoyl GA does not play a major role in the OR-1 antitrypsin activity. PMID:21606621

Habe, Hiroshi; Fukuoka, Tokuma; Sato, Shun; Kitamoto, Dai; Sakaki, Keiji

2011-01-01

316

Synthesis and biological activity of novel tiliroside derivants.  

PubMed

A series of new tiliroside derivatives were synthesized and characterized by analytical (1)H NMR, (13)C NMR and mass spectrometry. All of the compounds were evaluated for anti-diabetic properties in vitro using HepG2 cells. Compounds 3c, 3d, and 3i-l caused significant enhancements in glucose consumption by insulin-resistant HepG2 cells compared with control cells and cells that were exposed to metformin (an anti-diabetic drug). Moreover, compound 3l significantly activated adenosine 5'-monophosphate-activated protein kinase activity and reduced acetyl-CoA carboxylase activity. Thus, the tiliroside derivative 3l offers potential to be developed as a new approach for treating type II diabetes. PMID:21856048

Qin, Nan; Li, Chun-Bao; Jin, Mei-Na; Shi, Li-Huan; Duan, Hong-Quan; Niu, Wen-Yan

2011-10-01

317

Synthesis, Characterisation and Antitumour Activity of Some Quercetin Analogues  

PubMed Central

Quercetin is one of the most abundant naturally occurring flavonoid and is associated with a wide range of biological activities, such as antioxidant, antiinflammatory and anticancer activities. However, there are multiple problems associated with the bioavailability of quercetin, thereby restricting its use. Taking this into consideration, the structure of quercetin was modified by removal of multiple hydroxyl groups and introduction of substituents such as Cl, OCH3 and N (CH3)2 on the p-position of the B-ring. The effect of structural modification on the anticancer activity was studied using four different cell lines, including MCF-7, HepG2, HCT-15 and PC-3. Compound 1a has shown an activity better than quercetin in HepG2 cell lines, whereas 1c and 1e showed significant growth inhibition of the HCT-15 cell lines. PMID:24019576

Gadhwal, M. K.; Patil, Swati; D’Mello, Priscilla; Joshi, Urmila; Sinha, Ragini; Govil, G.

2013-01-01

318

Synthesis and antioxidant activity of aminomethylated 6-methyluracil derivatives  

Microsoft Academic Search

The Mannich reactions of 6-methyluracil and 5-nitro-6-methyluracil with piperidine, morpholine, and triazole were studied.\\u000a The antioxidant activities of the Mannich bases were comparable to that of the known antioxidant ionol.

Yu. N. Chernyshenko; A. G. Mustafin; A. R. Gimadieva; I. B. Abdrakhmanov; A. Ya. Gerchikov; I. V. Safarova

2010-01-01

319

Synthesis, reactions and biological activities of furochromones: A review.  

PubMed

Furochromone derivatives are important synthetic targets which showed a myriad of interesting biological activities. Ammi visnaga (Umbelliferae) is the most famous source of these derivatives, which has been used in folk medicine for millennia targeting different ailments. Since the isolation of furochromone derivatives, different synthetic methodologies were developed for their preparation. Despite the recent interesting findings on this class of compounds, the chemical literatures lack a comprehensive summary on the synthetic methodologies and biological activities of furochromone derivatives. This review highlights recent advances in furochromones chemistry by discussing different synthetic procedures developed for the preparation of naturally occurring derivatives as well as other unique derivatives which showed promising biological activities. It also sheds light on the most common reactions of furochromone derivatives and the utilization of these derivatives as the blocks for many biologically active compounds. PMID:25499986

Abu-Hashem, Ameen A; El-Shazly, Mohamed

2015-01-27

320

Synthesis, topoisomerase I inhibitory and cytotoxic activities of chromone derivatives.  

PubMed

A series of chromone derivatives were designed as potential topoisomerase I (Top I) inhibitors based on the docking simulation study. Sixteen synthesized compounds were evaluated for Top I inhibitory activity and some compounds were further tested for in vitro cytotoxic activity. The most potent inhibitor, chromone 11b showed greater inhibitory activity (IC50 = 1.46 ?M) than the known Top I inhibitors, i.e., camptothecin, fisetin and morin, but inactive against breast cancer cell (MCF-7), oral cavity cancer cell (KB) and small cell lung cancer (NCI-H187). Chromone 11c, another potent inhibitor (IC50 = 6.16 ?M), exhibited cytotoxic activity against KB (IC50 = 73.32 ?M) and NCI-H187 (IC50 = 36.79 ?M). PMID:23030699

Maicheen, Chirattikan; Jittikoon, Jiraphun; Vajragupta, Opa; Ungwitayatorn, Jiraporn

2013-05-01

321

Synthesis and biological activity of amide derivatives of nimbolide.  

PubMed

Nimbolide (1), a limonoid isolated from Azadirachta indica, is the chief cytotoxic principle in Neem leaves extract. Using nimbolide as a lead compound for anti-cancer analogue design, a series of nimbolide derivatives have been synthesized and evaluated for in vitro cytotoxic activity against a panel of human cancer cell lines. Out of 10 compounds screened 2g, 2h and 2i showed potent activity. PMID:16793266

Sastry, B S; Suresh Babu, K; Hari Babu, T; Chandrasekhar, S; Srinivas, P V; Saxena, A K; Madhusudana Rao, J

2006-08-15

322

Synthesis and structure-activity relationship of antifungal coniothyriomycin analogues.  

PubMed

The structure of the antifungal metabolite coniothyriomycin was systematically modified by changing the acids of the open chain imide, modification of the hydrophobicity, variation in the degree of saturation, replacement of carbons by nitrogen or oxygen, and incorporation of the open chain molecule into cyclic arrangements. Structure-activity studies showed that antifungal activity was retained by replacement of phenylacetic acids by benzoic acids in the imide structure but diminished by hydrogenation of the fumaric ester part. PMID:12760686

Krohn, Karsten; Elsässer, Brigitta; Antus, Sándor; Kónya, Krisztina; Ammermann, Eberhard

2003-03-01

323

Synthesis and SAR study of modulators inhibiting tRXR?-dependent AKT activation  

PubMed Central

RXR? represents an intriguing and unique target for pharmacologic interventions. We recently showed that Sulindac and a designed analog could bind to RXR? and modulate its biological activity, including inhibition of the interaction of an N-terminally truncated RXR? (tRXR?) with the p85? regulatory subunit of phosphatidylinositol-3-OH kinase (PI3K). Here we report the synthesis, testing and SAR of a series of novel analogs of Sulindac as potential modulators for inhibiting tRXR?-dependent AKT activation. A new compound 30 was identified to have improved biological activity. PMID:23434637

Wang, Zhi-Gang; Chen, Liqun; Chen, Jiebo; Zheng, Jian-Feng; Gao, Weiwei; Zeng, Zhiping; Zhou, Hu; Zhang, Xiao-kun; Huang, Pei-Qiang; Su, Ying

2013-01-01

324

Design, synthesis and in vitro antitumor activity evaluation of novel 4-pyrrylamino quinazoline derivatives  

PubMed Central

Here we describe the design and synthesis of two series of 4-pyrrylamino quinazolines as new analogues of the EGFR inhibitor Gefitinib. In vitro antitumor activity of these novel compounds against pancreatic (Miapaca2) and prostate (DU145) cancer cell lines was evaluated. Compared with the parental Gefitinib, all the 18 derivatives show a greatly increased cytotoxicity to cancer cells. In vitro kinase inhibitory activity on EGFR was also investigated. Among them, compounds GI-6, GII-4, GII-6, GII-8, and GII-9 are more potential RTK inhibitors. Based on these results, we propose simple structure-activity relationship to provide information for designing and developing more potent antitumor agents. PMID:21895983

Wu, Xiaoqing; Li, Mingdong; Tang, Wenhua; Zheng, Youguang; Lian, Jiqin; Xu, Liang; Ji, Min

2011-01-01

325

Biomimetically inspired total synthesis and structure activity relationships of 1-O-methyllateriflorone. 6 pi electrocyclizations in organic synthesis.  

PubMed

The total synthesis of 1-O-methyllateriflorone (2) is described. The construction of the cage-like domain of the molecule involved a biomimetic Claisen/Diels-Alder cascade, whereas the novel spiroxalactone framework was generated by an intramolecular Michael reaction within precursor 16a involving the carboxylate residue as the nucleophile. This finding might bear on the biosynthetic pathway by which nature forms lateriflorone. Described herein is also an interesting cascade sequence involving facile 6 pi electrocyclizations which leads to complex benzopyran systems. The biological evaluation of a small library of lateriflorone analogues and related systems establishing the first SAR within this class of compounds is also included. Among the most active compounds against tumor cells are 2, 16b, 56, 58, and 59. PMID:15113221

Nicolaou, K C; Sasmal, Pradip K; Xu, Hao

2004-05-01

326

Synthesis, anticancer activity and structure-activity relationship of some anticancer agents based on cyclopenta (b) thiophene scaffold.  

PubMed

Methods for the synthesis of new heterocyclic systems of thieno (3,2-d)- (1,2,3)-triazine derivatives and N-(3-cyano-5,6-dihydro-4H-cyclopenta (b) thiophene derivatives have been developed. The newly synthesized compounds were tested in vitro against human breast carcinoma cell line (MCF-7). Compounds 7 and 9 have shown the highest activity among the two synthesized series. The results of this study have led to the identification of two lead compounds with good inhibitory activities that can confirm the design of the next generation inhibitors of tyrosine kinase with fewer side effects such as hepatotoxicity and resistance. PMID:25015456

Said, Mohamed; Elshihawy, Hosam

2014-07-01

327

Synthesis and antibacterial activity of sulfonamides. SAR and DFT studies  

NASA Astrophysics Data System (ADS)

A series of substituted sulfonamide derivatives were synthesized from chlorosulfonyl isocyanate (CSI) in tree steps (carbamoylation, sulfamoylation and deprotection). Antibacterial activity in vitro of some newly formed compounds investigated against clinical strains Gram-positive and Gram-negative: Escherichia coli and Staphylococcus aureus applying the method of dilution and minimal inhibition concentration (MIC) methods. These compounds have significant bacteriostatic activity with totalities of bacterial strains used. DFT calculations with B3LYP/6-31G(d) level have been used to analyze the electronic and geometric characteristics deduced for the stable structure of three compounds presenting conjugation between a nitrogen atom N through its lone pair and an aromatic ring next to it. The principal quantum chemical descriptors have been correlated with the antibacterial activity.

Boufas, Wahida; Dupont, Nathalie; Berredjem, Malika; Berrezag, Kamel; Becheker, Imène; Berredjem, Hajira; Aouf, Nour-Eddine

2014-09-01

328

Synthesis and Antiinflammatory Activity of Newer Pyrazolinylbenzidines and Isoxazolinylbenzidines  

PubMed Central

In an effort to search for more active antiinflammatory agent, a series of pyrazolinylbenzidines and isoxazolylbenzidines was designed, synthesized, and screened for their potential as novel orally inflammation inhibitors. Compounds 4,4’-bis-(1”-acetyl-5”-substitutedaryl-2”-pyrazolin-3”-yl)benzidines (8-13) and 4,4’-bis-(2”-substitutedaryl-isoxazolin-4’-yl)benzidines (14-19) have been synthesized from 4,4’-bis-(substituted benzylidenyl-acetyl)benzidines (2-7). The structures of the products have been delineated by spectral and elemental analysis. Compounds 2-19 evaluated for antiinflammatory activity and acute toxicity and results are reported. The compound 4,4’-bis-[1”-acetyl-5”-(p-methoxyphenyl)-2”-pyrazolin-3’-yl)benzidine (9) showed more potent and dose-dependent antiinflammatory activity in comparison to reference drug. PMID:25284927

Sharma, S.; Saxena, K. K.

2014-01-01

329

Synthesis and Antitumor Activity of Natural Compound Aloe Emodin Derivatives.  

PubMed

In this study, we have synthesized novel water soluble derivatives of natural compound aloe emodin 4(a-j) by coupling with various amino acid esters and substituted aromatic amines, in an attempt to improve the anticancer activity and to explore the structure-activity relationships. The structures of the compounds were determined by (1) H NMR and mass spectroscopy. Cell growth inhibition assays revealed that the aloe emodin derivatives 4d, 4f, and 4i effectively decreased the growth of HepG2 (human liver cancer cells) and NCI-H460 (human lung cancer cells) and some of the derivatives exhibited comparable antitumor activity against HeLa (Human epithelial carcinoma cells) and PC3 (prostate cancer cells) cell lines compared to that of the parent aloe emodin at low micromolar concentrations. PMID:25323822

Thimmegowda, Naraganahalli R; Park, Chanmi; Shwetha, Bettaswamigowda; Sakchaisri, Krisada; Liu, Kangdong; Hwang, Joonsung; Lee, Sangku; Jeong, Sook J; Soung, Nak K; Jang, Jae H; Ryoo, In-Ja; Ahn, Jong S; Erikson, Raymond L; Kim, Bo Y

2014-10-17

330

Synthesis and antileishmanial activity of novel pyridinium-hydrazone derivatives.  

PubMed

A series of substituted phenylethylidenehydrazinylpyridinium derivatives bearing methyl, ethyl, propyl, and propylphenyl groups on the pyridinium nitrogen were synthesized and evaluated for in vitro antileishmanial activity against Leishmania tropica by using the microdilution method. Among the tested compounds, 3d, 5c, 3b, and 3c were found to be the most active derivatives against the promastigotes of L. tropica (IC50 values are 6.90, 9.92, 11.69 and 12.03 µM, respectively) and to be more active than reference drug meglumine antimonaite (glucantime) (IC50 value: 20.49 µM). The derivatives investigated in this study may have the potential to be lead compound against leishmanial infection. PMID:22803671

Alptuzun, Vildan; Cakiroglu, Gokcer; Limoncu, M Emin; Erac, Bayri; Hosgor-Limoncu, Mine; Erciyas, Ercin

2013-10-01

331

Synthesis and anticonvulsant activity of novel purine derivatives.  

PubMed

A series of new purines containing triazole and other heterocycle substituents was synthesized and evaluated for their preliminary anticonvulsant activity and neurotoxicity by using the maximal electroshock (MES), subcutaneous pentylenetetrazole (scPTZ) and rotarod neurotoxicity (TOX) tests. Among the compounds studied, 9-decyl-6-(1H-1,2,4-triazol-1-yl)-9H-purine (5e) was the most potent compound, with a median effective dose of 23.4 mg/kg and a high protective index of more than 25.6 after intraperitoneal administration in mice. Compound 5e showed significant oral activity against MES-induced seizures in mice, with an ED50 of 39.4 mg/kg and a PI above 31.6. These results demonstrate that compound 5e possesses better anticonvulsant activity and is safer than the commercially available drugs carbamazepine and valproate in MES, scPTZ and TOX models. PMID:25062008

Wang, Shi-Ben; Jin, Peng; Li, Fu-Nan; Quan, Zhe-Shan

2014-09-12

332

Synthesis and antimycobacterial activity of some phthalimide derivatives.  

PubMed

Structurally modified phthalimide derivatives were prepared through condensation of phthalic and tetrafluorophthalic anhydride with selected sulfonamides with variable yields. All compounds were screened for their antimycobacterium activity against Mycobacterium tuberculosis H37Ra (ATCC 25177) using a micro broth dilution technique. The fluorinated derivatives (compounds 2c, 2d, 2f and 2h) had antimycobacterium activity comparable with classical sulfonamide drugs. The minimum inhibitory concentration (MIC) of compounds 2c, 2d, 2f and 2h was greater than that of isoniazid (MIC<0.02 ?g/mL) and in vitro activity was greater than that of pyrazinamide, another first line antimycobacterium drug (MIC 50-100 ?g/mL). The new compounds could be considered new lead compounds in the treatment of multi-drug resistant tuberculosis. PMID:22633120

Akgün, Hülya; Karameleko?lu, Irem; Berk, Bark?n; Kurnaz, I??l; Sar?b?y?k, Gizem; Oktem, Sinem; Kocagöz, Tan?l

2012-07-01

333

Synthesis and Antimycobacterial Activity of 2,1?-Dihydropyridomycins  

PubMed Central

Dihydropyridomycins 2 and 3, which lack the characteristic enol ester moiety of the potent antimycobacterial natural product pyridomycin (1), have been prepared from l-Thr, R- and S-hydroxy isovaleric acid, and 3-pyridinecarboxaldehyde. The 2R isomer 2 shows only 4-fold lower anti-Mtb activity than 1, indicating that the enol ester moiety in the natural product is not critical for its biological activity. This finding establishes 2 as a potent and more practical lead for anti-TB drug discovery. PMID:24900646

2012-01-01

334

Concise synthesis of 2-benzazepine derivatives and their biological activity.  

PubMed

2-Benzazepines, which are potentially good candidates for new drug therapies to treat skin wounds, were readily prepared from substituted cinnamylamide via an intramolecular Friedel-Crafts reaction. With few steps and effective reactions, the procedure enables a rapid derivatization of 2-benzazepines. Moreover, optically active 4-substituted-2-benzazepines were prepared from chiral ?-substituted cinnamylamides, which were readily prepared by asymmetric ?-alkylation of chiral cinnamyl oxazolidinone amides. We have easily prepared a library of more than 20 derivatives and examined the biological activity of the compounds. PMID:22463127

So, Masahiro; Kotake, Tomoko; Matsuura, Kenji; Inui, Makoto; Kamimura, Akio

2012-04-20

335

[Synthesis and analgesic activities of phenyl piperazinyl aralkyl ketone derivatives].  

PubMed

To explore novel non-opioid analgesic agents, 16 compounds were synthesized and their structures were confirmed by 1H NMR and HR-MS. YX0611-1 was treated as the leading compound. The results of mice writhing model and hot plate model showed that compounds 2, 7, 8, 9, 11 and 15 had obvious analgesic activities in vivo. The test of affinity to mu, delta, kappa receptor displayed that active compounds didn't act on opioid receptor. The results of preliminary toxicity and pharmacokinetic tests showed that compound 7 had better safety and pharmacokinetic properties than that of YX0611-1, and it deserved further development. PMID:23387085

Xie, Peng; Wang, Guan; Zhang, Gui-Sen; Zhang, Li; Xu, Xiang-Qing; Guo, Lin; Li, Jian-Qi

2012-11-01

336

Synthesis and antibacterial activity of catecholate-ciprofloxacin conjugates.  

PubMed

The development of an efficient route to obtain artificial siderophore-antibiotic conjugates active against Gram-negative bacteria is crucial. Herein, a practical access to triscatecholate enterobactin analogues linked to the ciprofloxacin along with their antibacterial evaluation are described. Two series of conjugates were obtained with and without a piperazine linker which is known to improve the pharmacokinetics profile of a drug. A monocatecholate-ciprofloxacin conjugate was also synthesized and evaluated. The antibacterial activities against Pseudomonas aeruginosa for some conjugates are related to the iron concentration in the culture medium and seem to depend on the bacterial iron uptake systems. PMID:24972726

Fardeau, Sylvain; Dassonville-Klimpt, Alexandra; Audic, Nicolas; Sasaki, André; Pillon, Marine; Baudrin, Emmanuel; Mullié, Catherine; Sonnet, Pascal

2014-08-01

337

Synthesis and biological activity of some derivatives of rifamycin P.  

PubMed

A series of derivatives of rifamycin P, an antibiotic produced by fermentation of a mutant strain of Nocardia mediterranea or by chemical modification of rifamycin S, have been prepared. The structures of these compounds were determined by 1H NMR, IR, UV, and LC/MS. Their in vitro and in vivo antibacterial activities in comparison with rifampicin and two other rifamycins under investigation were evaluated. The derivatives were more active than rifamycin P against Mycobacterium avium complex and other slowly and rapidly growing nontuberculous mycobacteria which frequently cause systemic infection in patients with AIDS. 2'-(Diethylamino)rifamycin P (P/DEA) appears suitable for further investigation. PMID:2329569

Cavalleri, B; Turconi, M; Tamborini, G; Occelli, E; Cietto, G; Pallanza, R; Scotti, R; Berti, M; Romanó, G; Parenti, F

1990-05-01

338

Synthesis and biological activity of nifuroxazide and analogs. II.  

PubMed

Nifuroxazyde and six analogs were synthesized by varying the substitute from the para-position of the benzenic ring and the heteroatom of the heterocyclic ring. The MIC of seven resultant compounds was determined by serial dilutions, testing the ATCC 25923 strain of Staphylococcus aureus. A significant increase in the anti-microbial activity of thyophenic analogs, as compared with furanic and pyrrholic analogs, was observed. In addition, unlike the cyano and hydroxyl groups, the acetyl group promoted anti-microbial activity. PMID:10622109

Tavares, L C; Chisté, J J; Santos, M G; Penna, T C

1999-09-01

339

Synthesis of silver nanoparticles with antibacterial activity using the lichen Parmotrema praesorediosum  

PubMed Central

Development of a green chemistry process for the synthesis of silver nanoparticles has become a focus of interest. This would offer numerous benefits, including ecofriendliness and compatibility for biomedical applications. Here we report the synthesis of silver nanoparticles from the reduction of silver nitrate and an aqueous extract of the lichen Parmotrema praesorediosum as a reductant as well as a stabilizer. The physical appearance of these silver nanoparticles was characterized using ultraviolet-visible spectroscopy, electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction techniques. The results show that silver nanoparticles synthesized using P. praesorediosum have an average particle size of 19 nm with a cubic structure. The antibacterial activity of the synthesized silver nanoparticles was tested against eight micro-organisms using the disk diffusion method. The results reveal that silver nanoparticles synthesized using P. praesorediosum have potential antibacterial activity against Gram-negative bacteria. PMID:24379670

Mie, Ropisah; Samsudin, Mohd Wahid; Din, Laily B; Ahmad, Azizan; Ibrahim, Nazlina; Adnan, Siti Noor Adnalizawati

2014-01-01

340

Choline Transport Activity Regulates Phosphatidylcholine Synthesis through Choline Transporter Hnm1 Stability*  

PubMed Central

Choline is a precursor for the synthesis of phosphatidylcholine through the CDP-choline pathway. Saccharomyces cerevisiae expresses a single high affinity choline transporter at the plasma membrane, encoded by the HNM1 gene. We show that exposing cells to increasing levels of choline results in two different regulatory mechanisms impacting Hnm1 activity. Initial exposure to choline results in a rapid decrease in Hnm1-mediated transport at the level of transporter activity, whereas chronic exposure results in Hnm1 degradation through an endocytic mechanism that depends on the ubiquitin ligase Rsp5 and the casein kinase 1 redundant pair Yck1/Yck2. We present details of how the choline transporter is a major regulator of phosphatidylcholine synthesis. PMID:24187140

Fernández-Murray, J. Pedro; Ngo, Michael H.; McMaster, Christopher R.

2013-01-01

341

Choline transport activity regulates phosphatidylcholine synthesis through choline transporter Hnm1 stability.  

PubMed

Choline is a precursor for the synthesis of phosphatidylcholine through the CDP-choline pathway. Saccharomyces cerevisiae expresses a single high affinity choline transporter at the plasma membrane, encoded by the HNM1 gene. We show that exposing cells to increasing levels of choline results in two different regulatory mechanisms impacting Hnm1 activity. Initial exposure to choline results in a rapid decrease in Hnm1-mediated transport at the level of transporter activity, whereas chronic exposure results in Hnm1 degradation through an endocytic mechanism that depends on the ubiquitin ligase Rsp5 and the casein kinase 1 redundant pair Yck1/Yck2. We present details of how the choline transporter is a major regulator of phosphatidylcholine synthesis. PMID:24187140

Fernández-Murray, J Pedro; Ngo, Michael H; McMaster, Christopher R

2013-12-13

342

Mathematics of combustion  

Microsoft Academic Search

The applications of numerical techniques to the study of combustion processes is considered. The basic equations governing combustion processes are introduced, and some novel approaches to combustion reaction modelling are described. Among the specific applications discussed are: the Burger and Korteweg-de Vries equations of detonation processes; turbulent combustion modelling; and analysis of finite amplitude waves in combustible gases.

J. D. Buckmaster; H. Rabitz; F. A. Williams; W. Fickett; J. F. Clarke

1985-01-01

343

Combustion pressure sensor  

Microsoft Academic Search

A combustion pressure sensor is described for mounting on an internal combustion engine so as to have access to the interior of a combustion cylinder. The sensor consists of: a first diaphragm means adjacent a combustion region for deflecting as a function of the magnitude of adjacent pressure in the combustion region, and for acting as a gas tight seal

Bettman

1986-01-01

344

Synthesis and in vitro anthelmintic activity against Nippostrongylus brasiliensis of new 2-amino-4-hydroxy-delta-valerolactam derivatives.  

PubMed

The synthesis of a series of 2-amino-4-hydroxy-delta-valerolactam derivatives is described (compounds 4 to 10). These compounds showed a high anthelmintic in vitro activity against the Nippostrongylus brasiliensis model. PMID:9580122

Gordon, S; Costa, L; Incerti, M; Manta, E; Saldaña, J; Domínguez, L; Mariezcurrena, R; Suescun, L

1997-10-01

345

STRUCTURE-ACTIVITY STUDY OF PARACETAMOL ANALOGUES: INHIBITION OF REPLICATIVE DNA SYNTHESIS IN V79 CHINESE HAMSTER CELLS  

EPA Science Inventory

Experimental and theoretical evidence pertaining to cytotoxic and genotoxic activity of paracetamol in biological systems was used to formulate a simple mechanistic hypothesis to explain the relative inhibition of replicative DNA synthesis by a series of 19 structurally similar p...

346

Synthesis, biological activity, and bioavailability of moschamine, a safflomide-type phenylpropenoic acid amide found in Centaurea cyanus  

Technology Transfer Automated Retrieval System (TEKTRAN)

Moschamine is a safflomide-type phenylpropenoic acid amide originally isolated from Centaurea cyanus. This paper describes the synthesis, detection of serotoninergic and COX inhibitory activities, and bioavailability of moschamine. Moschamine was chemically synthesized and identified using NMR spect...

347

Lopinavir impairs protein synthesis and induces eEF2 phosphorylation via the activation of AMP-activated protein kinase.  

PubMed

HIV anti-retroviral drugs decrease protein synthesis, although the underlying regulatory mechanisms of this process are not fully established. Therefore, we investigated the effects of the HIV protease inhibitor lopinavir (LPV) on protein metabolism. We also characterized the mechanisms that mediate the effects of this drug on elongation factor-2 (eEF2), a key component of the translational machinery. Treatment of C2C12 myocytes with LPV produced a dose-dependent inhibitory effect on protein synthesis. This effect was observed at 15 min and was maintained for at least 4 h. Mechanistically, LPV increased the phosphorylation of eEF2 and thereby decreased the activity of this protein. Increased phosphorylation of eEF2 was associated with increased activity of its upstream regulators AMP-activated protein kinase (AMPK) and eEF2 kinase (eEF2K). Both AMPK and eEF2K directly phosphorylated eEF2 in an in vitro kinase assay suggesting two distinct paths lead to eEF2 phosphorylation. To verify this connection, myocytes were treated with the AMPK inhibitor compound C. Compound C blocked eEF2K and eEF2 phosphorylation, demonstrating that LPV affects eEF2 activity via an AMPK-eEF2K dependent pathway. In contrast, incubation of myocytes with rottlerin suppressed eEF2K, but not eEF2 phosphorylation, suggesting that eEF2 can be regulated independent of eEF2K. Finally, LPV did not affect PP2A activity when either eEF2 or peptide was used as the substrate. Collectively, these results indicate that LPV decreases protein synthesis, at least in part, via inhibition of eEF2. This appears regulated by AMPK which can act directly on eEF2 or indirectly via the action of eEF2K. PMID:18712774

Hong-Brown, Ly Q; Brown, C Randell; Huber, Danuta S; Lang, Charles H

2008-10-15

348

Activation of AMP-Activated Protein Kinase by AICAR Prevents Leucine Stimulated Protein Synthesis in Rat Skeletal Muscle1  

PubMed Central

Several stress conditions are characterized by activation of 5?-AMP-protein kinase (AMPK) and the development of leucine resistance in skeletal muscle. The present study determined whether direct activation of the AMPK by AICAR prevents the characteristic leucine-induced increase in protein synthesis by altering mTOR (mammalian target of rapamycin) signal transduction. Rats were injected with AICAR or saline and 1 h thereafter received an oral gavage of leucine (or saline). Efficacy of AICAR was verified by increased AMPK phosphorylation. AICAR decreased basal in vivo muscle (gastrocnemius) protein synthesis and completely prevented the leucine-induced increase, independent of a change in muscle adenine nucleotide concentration. AICAR also prevented the hyperphosphorylation of eukaryotic initiation factor (eIF) 4E binding protein (4E-BP1), ribosomal protein S6 kinase (S6K1), S6, and eIF4G in response to leucine suggesting a decrease in mTOR activity. Moreover, AICAR prevented the leucine-induced redistribution of eIF4E from the inactive eIF4E·4E-BP1 to the active eIF4E·eIF4G complex. This ability of AICAR to produce muscle leucine resistance could not be attributed to a change in phosphorylation of tuberous sclerosis complex (TSC)2, the formation of a TSC1·TSC2 complex, or the binding of raptor with mTOR, or the phosphorylation of eukaryotic elongation factor-2. However, the inhibitory actions of AICAR were associated with a reduction in the phosphorylation of proline-rich Akt substrate (PRAS)-40 and increased phosphorylation of raptor, and these represent potential mechanisms by which AICAR might be expected to inhibit leucine-induced increases in mTOR activity and protein synthesis under in vivo conditions. PMID:18806097

Pruznak, Anne M.; Kazi, Abid A.; Frost, Robert A.; Vary, Thomas C.; Lang, Charles H.

2008-01-01

349

Synthesis and Anticorrosion and Biocidal Activity of Triazoloazepine Derivatives  

Microsoft Academic Search

Inhibiting effect on acid corrosion of steel 45 and biocidal activity with respect to sulfate-reducing bacteria are studied for a series of N-aryl-N-(6,7,8,9-tetrahydro-5H-[1,2,4]triazolo[4,3-a]azepin-3-ylmethyl)amines.

A. M. Demchenko; K. G. Nazarenko; A. P. Makei; S. V. Prikhod'ko; I. N. Kurmakova; A. P. Tretyak

2004-01-01

350

Heteroatom Analogues of Hydrocodone: Synthesis and Biological Activity  

PubMed Central

Heteroatom analogues of hydrocodone, in which the N-methyl functionality was replaced with oxygen, sulfur, sulfoxide, and sulfone, were prepared by a short sequence from the ethylene glycol ketal of hydrocodone; a carbocyclic analogue of bisnorhydrocodone was also prepared. The compounds were tested for receptor binding and revealed moderate levels of activity for the sulfone analogue of hydrocodone. PMID:23397939

Giacometti, Robert D.; Duchek, Jan; Werner, Lukas; Husni, Afeef S.; McCurdy, Christopher R.; Cutler, Stephen J.; Cox, D. Phillip; Hudlicky, Tomas

2013-01-01

351

Synthesis and anticancer activity of (E)-2-benzothiazole hydrazones.  

PubMed

Benzothiazole hydrazones have been synthesized and evaluated for their in vitro antiproliferative activity against three human cancer cell lines: HL-60 (leukemia), MDAMB-435 (breast) and HCT-8 (colon). The good cytotoxicity for the three cancer cell lines and theoretical profile of compounds 3o and 3p pointed them as promising lead molecules for anticancer drug design. PMID:25147145

Lindgren, Eric B; de Brito, Monique A; Vasconcelos, Thatyana R A; de Moraes, Manuel O; Montenegro, Raquel C; Yoneda, Julliane D; Leal, Kátia Z

2014-10-30

352

Synthesis and antifungal activity of thiadiazole-functionalized chitosan derivatives.  

PubMed

A groups of novel water soluble chitosan derivatives containing 1,3,4-thiadiazole group were synthesized including 1,3,4-thiadiazole (TPCTS), 2-methyl-1,3,4-thiadiazole (MTPCTS), and 2-phenyl-1,3,4-thiadiazole (PTPCTS). Their antifungal activity against three kinds of phytopathogens was estimated by hypha measurement in vitro, and the fungicidal assessment shows that the synthesized chitosan derivatives have excellent activity against tested fungi. Of all the synthesized chitosan derivatives, MTPCTS inhibited the growth of the tested phytopathogens most effectively with inhibitory indices of 75.3%, 82.5%, and 65.8% against Colletotrichum lagenarium (Pass) Ell.et halst, Phomopsis asparagi (Sacc.) Bubak, and Monilinia fructicola (Wint.) Honey respectively at 1.0 mg/mL. These indices are higher than those of chitosan. These data also demonstrate that the hydrophobic moiety (alkyl and phenyl) and the length of alkyl substituent in thiadiazole tend to affect the antifungal activity of chitosan derivatives. It is hypothesized that thiadiazole groups enable the synthesized chitosan to possess obviously better antifungal activity and good solubility in water. PMID:23624516

Li, Qing; Ren, Jianming; Dong, Fang; Feng, Yan; Gu, Guodong; Guo, Zhanyong

2013-05-24

353

Synthesis and anticancer activity of a series of norcantharidin analogues.  

PubMed

Cantharidin (1) and norcantharidin (2) display high levels of anticancer activity against a broad range of tumour cell lines. Synthetic manipulation of norcantharidin yields (3S,3aR,4S,7R,7aS)-3-hydroxyhexahydro-4,7-epoxyisobenzofuran-1(3H)-one (3), which also displays a high level of anticancer activity against tumour cells but interestingly, shows selectivity towards HT29 (colon; GI(50) = 14 ?M) and SJ-G2 (glioblastoma; GI(50) = 15 ?M) cell lines. Substitution at the hydroxyl group of the cyclic lactone within (3) produces a diasteromeric pair of products that have no difference in cytotoxicity over the cell lines tested. Incorporation of an isopropyl tail at this position (16) produced the most promising compound of this series to date, with strong selectivity towards HT29 (colon; GI(50) = 19 ?M) and SJ-G2 (glioblastoma; GI(50) = 21 ?M) cell lines but completely void of any activity against the remaining tumour cell lines (GI(50) > 100 ?M), as per the parent molecule. We also discovered that the introduction of a terminal phosphate moiety (28) at the same position produced a different trend in cytotoxicity with strong activity in BE2-C (neuroblastoma; GI(50) = 9 ?M) cells; suggestive of an alternate mode of action. PMID:22796041

Tarleton, Mark; Gilbert, Jayne; Sakoff, Jennette A; McCluskey, Adam

2012-08-01

354

Synthesis, neuronal activity and mechanisms of action of halogenated enaminones.  

PubMed

Due to the excellent anticonvulsant activity of previously synthesized halogenated enaminones, more disubstituted analogs were synthesized and evaluated in vitro. The new enaminones either had no effect, depressed, or enhanced population spike (PS) amplitude in the rat hippocampus in a concentration-dependent manner. Structure-activity relationship (SAR) analysis indicated that compounds 21 and 25 (with dibromo substituents) were equipotent, and more potent than compound 2 (with dichloro substituents), with compound 25 being the most efficacious of all tested compounds. Both diiodo derivatives 30 and 31 tested produced no significant effect on PS. For PS depression, phenyl substitution on the cyclohexenone ring produced the most efficacious compound 25. PS depressing analogues also depressed evoked excitatory postsynaptic current (EPSC) and action potential firing frequency. Removal of phenyl or methyl group from position 6 on the cyclohexenone ring of enaminone esters produced compound 28 which exhibited pro-convulsant effects. There was no direct correlation between C log P values and anticonvulsant activity of the halogenated enaminones. The mechanisms of anticonvulsant activity were the indirect suppression of excitatory synaptic transmission by enhancing extracellular GABA, and the direct suppression of action potential firing of the neurons. PMID:24565570

Edafiogho, Ivan O; Qaddoumi, Mohamed G; Ananthalakshmi, Kethireddy V V; Phillips, Oludotun A; Kombian, Samuel B

2014-04-01

355

Synthesis and Antimalarial Activities of Cyclen 4-Aminoquinoline Analogs  

Technology Transfer Automated Retrieval System (TEKTRAN)

In an attempt to augment the efficacy of 7-chloro 4-aminoquinoline analogs and also to overcome resistance to anti-malarial agents we synthesized three cyclen analogs of chloroquine (4,6,7). Compound 4 displays the most potent in vitro and in vivo antimalarial activities. It displays an IC50 of 7.5 ...

356

Starburst99: Synthesis Models for Galaxies with Active Star Formation  

Microsoft Academic Search

Starburst99 is a comprehensive set of model predictions for spectrophotometric and related properties of galaxies with active star formation. The models are an improved and extended version of the data set previously published by Leitherer & Heckman. We have upgraded our code by implementing the latest set of stellar evolution models of the Geneva group and the model atmosphere grid

Claus Leitherer; Daniel Schaerer; Jeffrey D. Goldader; Rosa M. González Delgado; Carmelle Robert; Denis Foo Kune; Duília F. de Mello; Daniel Devost; Timothy M. Heckman

1999-01-01

357

Total Chemical Synthesis of Biologically Active Vascular Endothelial Growth Factor  

SciTech Connect

The 204-residue covalent-dimer vascular endothelial growth factor (VEGF, see picture) with full mitogenic activity was prepared from three unprotected peptide segments by one-pot native chemical ligations. The covalent structure of the synthetic VEGF was confirmed by precise mass measurement, and the three-dimensional structure of the synthetic protein was determined by high-resolution X-ray crystallography.

Mandal, Kalyaneswar; Kent, Stephen B.H. (UC)

2011-09-15

358

Facile Synthesis of Four Natural Triterpene Saponins with Important Antitumor Activity  

Microsoft Academic Search

The first synthesis of four natural triterpene saponins, which exhibit significant antitumor activities, was concisely achieved by adopting a stepwise glycosylation. The key intermediate 13 was afforded via Bu2SnO-mediated regioseletive benzoylation. During the preparation of the target compounds, it was found that the ?-L-arabinopyranosyl unit in intermediates 17 and 20 existed in the unusual C4 conformation, and after removing the

Tiantian Guo; Qingchao Liu; Lei Zhang; Peng Wang; Yingxia Li

2011-01-01

359

Stimulation of dopamine synthesis and activation of tyrosine hydroxylase by phorbol diesters in rat striatum  

SciTech Connect

In rat striatal synaptosomes, 4..beta..-phorbol 12-myristate 13-acetate (PMA) and 4 ..beta..-phorbol 12,13-dibutyrate (PDBu), two activators of Ca/sup 2 +/-phospholipid-dependent protein kinase (protein kinase C) increased dopamine (DA) synthesis measured by following the release of /sup 14/CO/sub 2/ from L-(1-/sup 14/C) tyrosine. Maximal stimulation (21-28% increase of basal rate) was produced by 0.5 ..mu..M PMA and 1 ..mu..M PDBu. 4 ..beta..-Phorbol and 4 ..beta..-phorbol 13-acetate, which are not activators of protein kinase C, were ineffective at 1 ..mu..M. PMA did not change the release of /sup 14/CO/sub 2/ from L-(1-/sup 14/C)DOPA. Addition of 1 mM EGTA to a Ca/sup 2 +/-free incubation medium failed to affect PMA stimulation. KCl (60 mM) enhanced DA synthesis by 25%. Exposure of synaptosomes to either PMA or PDBu prior to KCl addition resulted in a more than additive increase (80-100%) of DA synthesis. A similar synergistic effect was observed when the phorbol diesters were combined with either veratridine or d-amphetamine but not with forskolin and dibutyryl cyclic AMP. Pretreatment of striatal synaptosomes with phorbol diesters produced an activation of tyrosine hydroxylase (TH) associated with a 60% increase of the Vmax and a decrease of the Km for the pterine cofactor 6-methyl-5,6,7,8-tetrahydropterin. These results indicate that protein kinase C participates in the regulation of striatal TH in situ and that its activation may act synergistically with DA releasing agents in stimulating DA synthesis. 37 references, 3 figures, 3 tables.

Onali, P.; Olianas, M.C.

1987-03-23

360

A chemoselective oxidation of monosubstituted ethylene glycol: facile synthesis of optically active ?-hydroxy acids.  

PubMed

A mild and efficient method for the synthesis of optically active ?-hydroxy acids through chemoselective oxidation of monosubstituted ethylene glycols using the TEMPO-NaOCl reagent system is described. It is evident from our studies that the solvent, pH and reaction temperature are very crucial for the success of this oxidation. The versatility of this method has been demonstrated with a variety of aliphatic, aromatic and carbohydrate substrates bearing various functional groups. PMID:24850510

Chinthapally, Kiran; Baskaran, Sundarababu

2014-07-01

361

Synthesis and HIV-1 integrase inhibitory activities of caffeic acid dimers derived from Salvia officinalis.  

PubMed

The synthesis of two caffeoyl-coumarin conjugates, derived from sagecoumarin, has been accomplished, starting from ferulic acid, isoferulic acid and sesamol. Both compounds exhibited potent inhibitory activities at micromolar concentrations against HIV-1 integrase in 3'-end processing reaction but were less effective against HIV-1 replication in a single-round infection assay of HeLa-beta-gal-CD4+ cells. PMID:16183277

Bailly, Fabrice; Queffelec, Clémence; Mbemba, Gladys; Mouscadet, Jean-François; Cotelle, Philippe

2005-11-15

362

Synthesis and antimicrobial activity of symmetrical two-tailed dendritic tricarboxylato amphiphiles  

E-print Network

Synthesis and antimicrobial activity of symmetrical two-tailed dendritic tricarboxylato amphiphiles dendritic amphiphiles--R2NCONHC((CH2)2COOH)3, 2(n,n), and R2CHNHCONHC((CH2)2COOH)3, 3(n,n), where R = n-CnH2 moiety of an amphiphile, highly hydrophobic headgroups are needed to enable solubility in water. Our

Falkinham, Joseph

363

Synthesis and antitumor activity of some curcumin analogs.  

PubMed

In this study, four new curcurmin analogs (compounds 1, 2, 17 and 18) were synthesized. 17 [3,5-bis(4-hydroxy-3-methoxy-5-methylcinnamyl)N-methylpiperidone] showed high activity with GI50, TGI, and LC50 MG-MID values of 21.3, 70.7, and 97.7 microM, respectively. 18 [3,5-bis(4-hydroxy-3-methoxy-5-methylcinnamyl)-N-ethylpiperidone] showed the highest activity in this study with GI50, TGI, LC50 MG-MID values of 4.4, 33.8, 89.1 microM, respectively. 18 is even more active than curcumin with GI50, TGI, LC50 MG-MID values of 38.4, 35.6, 66.0 microM; respectively. 8 showed moderate selectivity towards Leukemia cell line-subpanel with a ratio of 5.6 (curcumin ratio: 1.2 for the same subpanel). The in vitro anti-tumor screening reveals that the results go hand in hand with the in vitro free radical scavenging effects. The antioxidant effect of these compounds depends mainly on the stabilization of the formed phenoxy free radical for which the p-hydroxy phenyl moiety is essential. o-substitution by electron-donating groups like the o-methoxy group (and to a even higher degree by the ethoxy group) increases the stability of phenoxy free radical, hence increasing both free scavenging and anti-tumor effects. Increasing the alkyl group chain on the N in the series of substituted N-alkyl piperidones as well as the extension of conjugation, increases the stabilization of phenoxy free radical and thereby the activity towards both free radical scavenging and anti-tumor effects. This may be attributed to an increased positive inductive effect and/or increased lipophilicity of the new compounds, a fact which is proven by the superior activities of compounds 17 and 18. PMID:15864788

Youssef, Khairia M; El-Sherbeny, Magda A

2005-04-01

364

Recombinant Neuregulin 1 Does Not Activate Cardiomyocyte DNA Synthesis in Normal or Infarcted Adult Mice  

PubMed Central

Objectives Neuregulin 1 signaling plays an important role in cardiac trabecular development, and in sustaining functional integrity in adult hearts. Treatment with neuregulin 1 enhances adult cardiomyocyte differentiation, survival and/or function in vitro and in vivo. It has also been suggested that recombinant neuregulin 1?1 (NRG1?1) induces cardiomyocyte proliferation in normal and injured adult hearts. Here we further explore the impact of neuregulin 1 signaling on adult cardiomyocyte cell cycle activity. Methods and Results Adult mice were subjected to 9 consecutive daily injections of recombinant NRG1?1 or vehicle, and cardiomyocyte DNA synthesis was quantitated via bromodeoxyuridine (BrdU) incorporation, which was delivered using mini-osmotic pumps over the entire duration of NRG1?1 treatment. NRG1?1 treatment inhibited baseline rates of cardiomyocyte DNA synthesis in normal mice (cardiomyocyte labelling index: 0.019±0.005% vs. 0.003±0.001%, saline vs. NRG1?1, P<0.05). Acute NRG1?1 treatment did result in activation of Erk1/2 and cardiac myosin regulatory light chain (down-stream mediators of neuregulin signalling), as well as activation of DNA synthesis in non-cardiomyocytes, validating the biological activity of the recombinant protein. In other studies, mice were subjected to permanent coronary artery occlusion, and cardiomyocyte DNA synthesis was monitored via tritiated thymidine incorporation which was delivered as a single injection 7 days post-infarction. Daily NRG1?1 treatment had no impact on cardiomyocyte DNA synthesis in the infarcted myocardium (cardiomyocyte labelling index: 0.039±0.011% vs. 0.027±0.021%, saline vs. NRG1?1, P>0.05). Summary These data indicate that NRG1?1 treatment does not increase cardiomyocyte DNA synthesis (and consequently does not increase the rate of cardiomyocyte renewal) in normal or infarcted adult mouse hearts. Thus, any improvement in cardiac structure and function observed following neuregulin treatment of injured hearts likely occurs independently of overt myocardial regeneration. PMID:25545368

Reuter, Sean; Soonpaa, Mark H.; Firulli, Anthony B.; Chang, Audrey N.; Field, Loren J.

2014-01-01

365

AMP-Activated Kinase Restricts Rift Valley Fever Virus Infection by Inhibiting Fatty Acid Synthesis  

PubMed Central

The cell intrinsic innate immune responses provide a first line of defense against viral infection, and often function by targeting cellular pathways usurped by the virus during infection. In particular, many viruses manipulate cellular lipids to form complex structures required for viral replication, many of which are dependent on de novo fatty acid synthesis. We found that the energy regulator AMPK, which potently inhibits fatty acid synthesis, restricts infection of the Bunyavirus, Rift Valley Fever Virus (RVFV), an important re-emerging arthropod-borne human pathogen for which there are no effective vaccines or therapeutics. We show restriction of RVFV both by AMPK and its upstream activator LKB1, indicating an antiviral role for this signaling pathway. Furthermore, we found that AMPK is activated during RVFV infection, leading to the phosphorylation and inhibition of acetyl-CoA carboxylase, the first rate-limiting enzyme in fatty acid synthesis. Activating AMPK pharmacologically both restricted infection and reduced lipid levels. This restriction could be bypassed by treatment with the fatty acid palmitate, demonstrating that AMPK restricts RVFV infection through its inhibition of fatty acid biosynthesis. Lastly, we found that this pathway plays a broad role in antiviral defense since additional viruses from disparate families were also restricted by AMPK and LKB1. Therefore, AMPK is an important component of the cell intrinsic immune response that restricts infection through a novel mechanism involving the inhibition of fatty acid metabolism. PMID:22532801

Moser, Theresa S.; Schieffer, Daniel; Cherry, Sara

2012-01-01

366

Bismuth-based oxide semiconductors: Mild synthesis and practical applications  

NASA Astrophysics Data System (ADS)

In this dissertation study, bismuth based oxide semiconductors were prepared using 'mild' synthesis techniques---electrodeposition and solution combustion synthesis. Potential environmental remediation and solar energy applications of the prepared oxides were evaluated. Bismuth vanadate (BiVO4) was prepared by electrodeposition and solution combustion synthesis. A two step electrosynthesis strategy was developed and demonstrated for the first time. In the first step, a Bi film was first electrodeposited on a Pt substrate from an acidic BiCl3 medium. Then, this film was anodically stripped in a medium containing hydrolyzed vanadium precursor, to generate Bi3+, and subsequent BiVO4 formation by in situ precipitation. The photoelectrochemical data were consistent with the in situ formation of n-type semiconductor films. In the solution combustion synthesis procedure, BiVO4 powders were prepared using bismuth nitrate pentahydrate as the bismuth precursor and either vanadium chloride or vanadium oxysulfate as the vanadium precursor. Urea, glycine, or citric acid was used as the fuel. The effect of the vanadium precursor on the photocatalytic activity of combustion synthesized BiVO 4 was evaluated in this study. Methyl orange was used as a probe to test the photocatalytic attributes of the combustion synthesized (CS) samples, and benchmarked against a commercial bismuth vanadate sample. The CS samples showed superior activity to the commercial benchmark sample, and samples derived from vanadium chloride were superior to vanadium oxysulfate counterparts. The photoelectrochemical properties of the various CS samples were also studied and these samples were shown to be useful both for environmental photocatalytic remediation and water photooxidation applications. Silver bismuth tungstate (AgBiW2O8) nanoparticles were prepared for the first time by solution combustion synthesis by using silver nitrate, bismuth nitrate, sodium tungstate as precursors for Ag, Bi, and W respectively and urea as the fuel. The photocatalytic activity of these nanoparticles was superior to a sample prepared by solid-state synthesis. The combustion-synthesized particles were subsequently modified with Pt catalyst islands using a photodeposition technique and then used for the photo-generation of syngas (CO + H2). Formic acid was used in these experiments for in situ generation of CO2 and its subsequent reduction to CO. In the absence of Pt modification, H2 was not obtained. These results were compared with those obtained with acetic acid in place of formic acid, and finally the mechanistic pathways for syngas and methane photogeneration are presented.

Timmaji, Hari Krishna

367

A model-based self-tuning controller for kinetically controlled combustion instability  

Microsoft Academic Search

Combustion instability is one of the distinct characteristics in continuous combustion processes such as gas turbines, ramjet engines and afterburners. This combustion instability often occurs near blow limit and high thermal out conditions and generates large amplitudes of heat release and pressure oscillations. Active control has been used to suppress combustion instability, but due to complex dynamics of the combustion

Anuradha Annaswamy; Ahmed Ghoniem

2002-01-01

368

Synthesis and antioxidant activities of Coenzyme Q analogues.  

PubMed

A series of 2,3-dimethoxy-5-methyl-1,4-benzoquinones (Coenzyme Q) substituted at the C-6 position with various groups were designed and synthesized based on the Coenzyme Q10 as potent antioxidant. In vitro antioxidant activities of these compounds were evaluated and compared with commercial antioxidant Coenzyme Q10 employing DPPH assay. All these synthesized Coenzyme Q analogues are found to exhibit good antioxidant activities. Of which Compound 8b bearing a N-benzoylpiperazine group at the C-6 position showed more potent inhibition of DPPH radical than Coenzyme Q10. All these results suggested the applicability of the Coenzyme Q analogues as potent antioxidants for combating oxidative stress. PMID:25232967

Wang, Jin; Li, Shuo; Yang, Tao; Yang, Jian

2014-10-30

369

Synthesis and anti-cancer activity of chalcone linked imidazolones.  

PubMed

A series of novel chalcone linked imidazolones were prepared and evaluated for their anti-cancer activity against a panel of 53 human tumour cell lines derived from nine different cancer types: leukemia, lung, colon, CNS, melanoma, ovarian, renal, prostate and breast. Some of these hybrids (6, 7 and 8) showed good anti-cancer activity with GI(50) values ranging from 1.26 to 13.9 microM. When breast carcinoma cells (MCF-7) were treated with 10 microM concentration of compounds TMAC, CA-4, 6 and 8 cell cycle arrest was observed in G2/M phase. Surprisingly, the increased concentration of the same compound to 30 microM caused accumulation of cells in G0/G1 phase of the cell cycle. PMID:20637611

Kamal, Ahmed; Ramakrishna, G; Raju, P; Viswanath, A; Ramaiah, M Janaki; Balakishan, G; Pal-Bhadra, Manika

2010-08-15

370

Synthesis and Analgesic Activity of Novel Hydrazide and Hydrazine Derivatives  

PubMed Central

The uses of non-steroidal anti-inflammatory drugs (NSAIDs) are limited by a variety of side effects. So research on preparing new analgesic agents is important. According to some reports about the analgesic activity of hydrazide and hydrazine derivatives a new series of these compounds were synthesized in order to obtain new analgesic compounds. The final compounds 10a-10e and 15a-15d were prepared by condensation of corresponding hydrazides 7,8 and 11-14 with different aldehydes 9a-9e. The structures of all synthesized compounds were confirmed by means of FT-IR, 1H-NMR and Mass spectra. All compounds were evaluated for their analgesic activities by abdominal constriction test (writhing test). Most of the synthesized compounds induced significant reduction in the writhing response when compared to control and compound 15 was more potent than mefenamic acid in the writhing test. PMID:24523751

Nassiri Koopaei, Mansur; Assarzadeh, Mohammad Javad; Almasirad, Ali; Ghasemi-Niri, Seyedeh Farnaz; Amini, Mohsen; Kebriaeezadeh, Abbas; Nassiri Koopaei, Nasser; Ghadimi, Maryam; Tabei, Arash

2013-01-01

371

Synthesis of 2-Acyloxycyclohexylsulfonamides and Evaluation on Their Fungicidal Activity  

PubMed Central

Eighteen N-substituted phenyl-2-acyloxycyclohexylsulfonamides (III) were designed and synthesized by the reaction of N-substituted phenyl-2-hydroxyl-cycloalkylsulfonamides (I, R1) with acyl chloride (II, R2) in dichloromethane under the catalysis of TMEDA and molecular sieve. High fungicidal active compound N-(2,4,5-trichlorophenyl)-2-(2-ethoxyacetoxy) cyclohexylsulfonamide (III-18) was screened out. Mycelia growth assay against the Botrytis cinerea exhibited that EC50 and EC80 of compound III-18 were 4.17 and 17.15 ?g mL?1 respectively, which was better than the commercial fungicide procymidone (EC50 = 4.46 ?g mL?1 and EC80 = 35.02 ?g mL?1). For in vivo activity against B. cinerea in living leaf of cucumber, the control effect of compound III-18 was better than the fungicide cyprodinil. In addition, this new compound had broader fungicidal spectra than chlorothalonil. PMID:24240812

Li, Xinghai; Cui, Zining; Chen, Xiaoyuan; Wu, Decai; Qi, Zhiqiu; Ji, Mingshan

2013-01-01

372

Synthesis and herbicidal activity of substituted pyrazole isothiocyanates.  

PubMed

Isothiocyanates and substituted pyrazoles were combined to form a series of novel isothiocyanates with highly effective herbicidal activity. The target compounds were analyzed by elemental analysis, 1H-NMR, EI-MS and IR spectroscopy. The synthesized compounds, particularly compounds 3-1 and 3-7, exhibited good herbicidal activities against four weeds. The EC(50) values of compound 3-1 against Echinochloa crusgalli L., Cyperus iria L., Dactylis glomerata L., and Trifolium repens L. were 64.32, 65.83, 62.42, and 67.72 µg/mL, respectively. The EC(50) values of compound 3-7 against E. crusgalli L., C. iria L., D. glomerata L., T. repens L. were 65.33, 64.90, 59.41 and 67.41 µg/mL, respectively. Compounds 3-1 and 3-7 may be further optimized as lead compounds for new herbicides. PMID:23075815

Wu, Hua; Feng, Jun-Tao; Lin, Kai-Chun; Zhang, Xing

2012-01-01

373

Synthesis and anti-tumor activity of glycosyl oxadiazoles derivatives.  

PubMed

A new series of glycosyl oxadiazoles compounds were synthesized and characterized through (1)H NMR, (13)C NMR, IR and HRMS. The anti-tumor activities for MDA-MB-231 of all these new compounds were screened in vitro by MTT assay. Due to the modification of gastrodin analogues, the anti-tumor activities of these 1,3,4-oxadiazoles derivatives were greatly improved. Six compounds (6 c, 6 d, 6 i, 6 j, 6 k and 6 l) displayed relatively higher MDA-MB-231 potency with IC50 values (0.89, 0.26, 1.35, 3.60, 0.95 and 1.08 ?M) compared with the reference medicine Rosiglitazone (5.23 ?M). PMID:25278236

Du, Kui; Cao, Xianting; Zhang, Pengfei; Zheng, Hui

2014-11-15

374

Synthesis of Y3Ba5Cu8O18 superconductor powder by auto-combustion reaction: Effects of citrate-nitrate ratio  

NASA Astrophysics Data System (ADS)

In this experiment, nanocrystalline Y3Ba5Cu8O18 superconductor powder was prepared by citrate-nitrate auto-combustion reaction. A series of Y3Ba5Cu8O18 precursor gels with different citrate-nitrate ratio ranged from 0.3 to 1.0 have been prepared by varying the amount of citric acid added. The auto-combustion reaction during drying process transformed the precursor gels into ashes powder that upon calcinations at 900 °C yield Y3Ba5Cu8O18 nanocrystalline powders. The TG/DTA analysis reveals that the precursor gels with 0.3 ? c/n < 1.0 decomposed in a single-step reaction combusted at temperature of around 230 °C. Established from XRD and SEM characterization, the Y3Ba5Cu8O18 calcined powder prepared from c/n = 0.7 precursor gels has got the orthorhombic structure with smallest particle size (?10 nm) compared to the rest of the batches. Samples with c/n = 0.5 and 0.7 appeared in this work to be electrically superconducting at temperature above 100 K as measured using standard four-probe technique. This emphasized on maintaining a stoichiometric or near stoichiometric reaction for the analysis.

Suan, Mohd Shahadan Mohd; Johan, Mohd Rafie; Chua Siang, Tat

2012-10-01

375

Facile synthesis, antioxidant and antimicrobial activity of amino methylene bisphosphonates.  

PubMed

A green and efficient preparation method for the amino bisphosphonates is accomplished by simple mixing and stirring of diethylphosphite, triethylorthoformate and various amines in the presence of amberlyst-15 as catalyst at room temperature under solvent free conditions. The title compounds are characterized by IR, (1)H-, (13)C-, (31)P-NMR and mass spectra, also studied their antimicrobial and antioxidant activity. PMID:22223381

Kunda, Uma Maheswara Rao; Balam, Satheesh Krishna; Nemallapudi, Bakthavatchala Reddy; Chereddy, Syama Sundar; Nayak, Sandip Kumar; Cirandur, Suresh Reddy

2012-01-01

376

Synthesis and biological activity of novel shikonin analogues.  

PubMed

A series of shikonin analogues with side chain variants have been synthesized and evaluated for antitumor activity. These novel analogues show a broad spectrum of in vitro cytotoxicity against various cancer cell lines. Additionally, some analogues were also found to have the ability to decrease the expression level of HIF-1alpha in breast cancer cells MDA-MB-231 under hypoxia. The features of these analogues suggest their potential in cancer therapy. PMID:19111464

Wang, Wenjing; Dai, Mei; Zhu, Caihua; Zhang, Jiangang; Lin, Liping; Ding, Jian; Duan, Wenhu

2009-02-01

377

Synthesis and Properties of Eu 3+ Activated Strontium Molybdate Phosphor  

Microsoft Academic Search

In order to prepare fluorescent material for white Light Emitting Diodes (LEDs), a new Eu3+ activated molyb-date phosphor SrMoO4 was fabricated with solid-state method. X-ray diffraction (XRD) showed that the doping of trivalent europium ion reduced the lattice parameters. The excitation and emission spectra indicated that this phosphor could be excited effectively by the visible light, and then emitted red

Li Xu; Yang Zhiping; Guan Li; Guo Qinglin; Huai Sufang; Li Panlai

2007-01-01

378

Influence of Mechanical Activation on Synthesis of Zinc Metatitanate  

Microsoft Academic Search

Investigations of a ZnO-TiO2 binary oxide mixture during mechanical treatment were mainly focused on obtaining orthotitanate Zn2TiO4 with a spinel structure. Due to the specific way of energy transfer during mechanical treatment using a high-energy ball mill, the system passes through low temperature ZnTiO3 metatitanate phase formation. Mechanical activation was performed on an equimolar ratio mixture of ZnO and TiO2.

N. Labus; N. Obradovi?; T. Sre?kovi?; V. Miti?; M. M. Risti?

379

Inhibitory activity of tryptanthrin on prostaglandin and leukotriene synthesis.  

PubMed

The indolo[2,1- b]quinazoline alkaloid tryptanthrin has previously been identified as the cyclooxygenase-2 (COX-2) inhibitory principle in the extract ZE550 prepared from the medicinal plant Isatis tinctoria (Brassicaceae). We here investigated the potential inhibitory activity of tryptanthrin and ZE550 on COX-2, COX-1 in cellular and cell-free systems. A certain degree of selectivity towards COX-2 was observed when COX-1-dependent formation of thromboxane B(2) (TxB(2)) in HEL cells and COX-2-dependent formation of 6-ketoprostaglandin F(1alpha) (6-keto-PGF(1alpha)) in Mono Mac 6 and RAW 264.7 cells were compared. Preferential inhibition of COX-2 by two orders of magnitude was found in phorbol myristate acetate (PMA) activated bovine aortic coronary endothelial cells (BAECs). Assays with purified COX isoenzymes from sheep confirmed the high selectivity towards COX-2. The leukotriene B(4) (LTB(4)) release from calcium ionophore-stimulated human granulocytes (neutrophils) was used as a model to determine 5-lipoxygenase (5-LOX) activity. Tryptanthrin and the extract ZE550 inhibited LTB(4) release in a dose dependent manner and with a potency comparable to that of the clinically used 5-LOX inhibitor zileuton. PMID:12391548

Danz, Henning; Stoyanova, Stefka; Thomet, Olivier A R; Simon, Hans-Uwe; Dannhardt, Gerd; Ulbrich, Holger; Hamburger, Matthias

2002-10-01

380

Synthesis and anti-influenza activities of novel baicalein analogs.  

PubMed

A series of novel flavones derivatives were synthesized based on modification of the active ingredients of a traditional Chinese medicine Scutellaria baicalensis GEORGI and screened for anti-influenza activity. The synthetic baicalein (flavone) analogs, especially with the B-rings substituted with bromine atoms, were much more potent than oseltamivir or ribavirin against H1N1 Tamiflu-resistant (H1N1 TR) virus and usually with more favorable selectivity. The most promising were 5b, 5c, 6b and 6c, all displaying an 50% effective concentration (EC50) at around 4.0-4.5?µM, and a selective index (SI=50% cytotoxic concentration (CC50)/EC50)>70. For seasonal H3N2-infected influenza virus, both 5a and 5b with SI >17.3 indicated superior to ribavirin. The flavonoids having both not-naturally-occurring bromo-substituted B-rings and appropriate hydroxyls positioning on the A-rings might be critical in determining the activity and selectivity against H1N1-Tamiflu-resistant infected influenza viruses. PMID:24572377

Chung, Shu-Ting; Chien, Pei-Yu; Huang, Wen-Hsin; Yao, Chen-Wen; Lee, An-Rong

2014-01-01

381

Plumbagin analogs-synthesis, characterization, and antitubercular activity  

PubMed Central

Considering the emerging problem of drug resistance in tuberculosis, there is an urgent need of development of new analogs that are useful in curing drug resistant tuberculosis. In India, tuberculosis continues to remain one of the most pressing health problems. India is the highest tuberculosis burden country in the world, accounting one fifth of global incidence - estimated 2.0-2.5 million cases annually. In 2011, approximately 8.7 million new cases of tuberculosis and 1.4 million people die from tuberculosis each year worldwide. Current antitubercular therapies are successful against normal tuberculosis but it is not suitable for drug resistant tuberculosis. In this study Plumbagin analogs, obtained from Plumbago zeylanica (Family-Plumbaginaceae), have been synthesized. Out of the various synthesized analogs, the antitubercular activity of compound a and b was evaluated using standard H37Rv and S, H, R, and E sensitive M tuberculosis strains using LRF assay method. Compound a showed strong activity against both standard H37Rv and S, H, R and E sensitive M. tuberculosis strains as compared to standard Rifampicin. The other compounds are proved to be more active against standard H37Rv and S, H, R and E sensitive M. tuberculosis strain as compared to Rifampicin. PMID:24696815

Nayak, Nishi; Bajpai, Meenakshi; Razdan, Balkishen

2014-01-01

382

Design, Synthesis, and Monitoring of Light-Activated Motorized Nanomachines  

NASA Astrophysics Data System (ADS)

Our group has developed a family of single molecules termed nanocars, which are aimed at performing controllable motion on surfaces. In this work, a series of light-activated motorized nanomachines incorporated with a MHz frequency light-activated unidirectional rotary motor were designed and synthesized. We hope the light-activated motor can serve as the powering unit for the nanomachines, and perform controllable translational motion on surfaces or in solution. A series of motorized nanovehicles intended for scanning tunneling microscopy (STM) imaging were designed and synthesized. A p-carborane-wheeled motorized nanocar was synthesized and monitored by STM. Single-molecule imaging was accomplished on a Cu(111) surface. However, further manipulations did lead to motor induced lateral motion. We attributed this result to the strong molecule-surface interactions between the p-carborane-wheeled nanocar and the Cu(111) surface and possible energy transfer between the rotary motor and the Cu(111) surface. To fine-tune the molecule-surface interactions, an adamantane-wheeled motorized nanocar and a three-wheel nanoroadster were designed and synthesized. In addition, the STM substrates will be varied and different combinations of molecule-surface interactions will be studied. As a complimentary imaging method to STM, single-molecule fluorescence microscopy (SMFM) also provides single-molecule level resolution. Unlike STM experiment requires ultra-high vacuum and conductive substrate, SMFM experiment is conducted at ambient conditions and uses non-conductive substrate. This imaging method allows us to study another category of molecule-surface interactions. We plan to design a fluorescent motorized nanocar that is suitable for SMFM studies. However, both the motor and fluorophore are photochemically active molecules. In proximity, some undesired energy transfer or interference could occur. A cyanine 5- (cy5-) tagged motorized nanocar incorporated with the MHz motor was designed and synthesized in order to minimize the potential energy transfer or interference between the motor and the fluorophore. The SMFM study of this cy5-tagged motorized nanocar is currently undergoing. The design of light-activated motorized nanocar inspired the design of nanosubmarines. We used fluorescence quenching and fluorescence correlation spectroscopy (FCS) to study the diffusion of single molecules. The fluorescence quenching experiments of Ru(bpy)3+2 by a quenching nanosubmarine was conducted, but no motor induced acceleration of the molecule were observed. Another fluorescent nanosubmarine was monitored by FCS, and no increase of diffusion coefficient was found. Finally, a 1-D channel approach was adopted for decreasing the effects of Brownian motion, and acceleration of nanosubmarine was observed.

Chiang, Pinn-Tsong

383

Combustion Control  

E-print Network

casing of the fuel control regulator with the combustion air piping. The upstream pressure on the burner air orifice is applied to the main diaphragm of the pressure balanced regulator. Assuming sufficient gas pressure at the regulator inlet..., the outlet gas pressure will equal the air impulse pressLre. As the primary control drive moves to open or close the air valve, the outlet pressure will "track" changes in air pressure. The burner is an orifice for the air (assuming that it is in good...

Riccardi, R. C.

1984-01-01

384

Utilization of blended fluidized bed combustion (FBC) ash and pulverized coal combustion (PCC) fly ash in geopolymer  

Microsoft Academic Search

In this paper, synthesis of geopolymer from fluidized bed combustion (FBC) ash and pulverized coal combustion (PCC) fly ash was studied in order to effectively utilize both ashes. FBC-fly ash and bottom ash were inter-ground to three different finenesses. The ashes were mixed with as-received PCC-fly ash in various proportions and used as source material for synthesis of geopolymer. Sodium

Prinya Chindaprasirt; Ubolluk Rattanasak

2010-01-01

385

Synthesis and photocatalytic activity of electrospun niobium oxide nanofibers  

SciTech Connect

Graphical abstract: Different morphologies are obtained for the electrospun niobium oxide nanofibers with different phase structures. The nanofibers of the two phase structures present different band gap value and the light absorption. Hexagonal phase nanofibers show better photocatalytic activity compared with the orthorhombic nanofibers. Highlights: ? Niobium oxide nanofibers of two phase structures were fabricated by electrospinning. ? Photocatalytic properties of the niobium oxide nanofibers were first explored. ? Nanofibers of different phase structures showed different photocatalytic activities. ? Reasons for the differences in the photocatalysis were carefully discussed. - Abstract: Niobium oxide (Nb{sub 2}O{sub 5}) nanofibers have been synthesized by sol–gel based electrospinning technique. Pure hexagonal phase (H-Nb{sub 2}O{sub 5}) and orthorhombic phase (O-Nb{sub 2}O{sub 5}) nanofibers were obtained by thermally annealing the electrospun Nb{sub 2}O{sub 5}/polyvinylpyrrolidone composite fibers in air at 500 °C and 700 °C, respectively. The fibers were characterized using the X-ray diffraction, scanning electron microscopy, specific surface area analyzer and UV–vis diffuse reflectance spectroscopy. Photocatalytic activities of the obtained nanofibers were evaluated depending on the degradation of methyl orange. The results indicate that the heat-treatment temperature, the crystalline structure and the morphology affected the physical and chemical properties of the as-prepared Nb{sub 2}O{sub 5} nanofibers. The H-Nb{sub 2}O{sub 5} nanofibers obtained at lower temperature showed better potential for the application as a promising photocatalyst.

Qi, Shishun [Institute of Electro Ceramics and Devices, School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Zuo, Ruzhong, E-mail: piezolab@hfut.edu.cn [Institute of Electro Ceramics and Devices, School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Liu, Yi [Institute of Electro Ceramics and Devices, School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Wang, Yu [Department of Applied Physics and Materials Research Center, The Hong Kong Polytechnic University, Hong Kong (China)

2013-03-15

386

Amplifier insensitive integrator design for active RC filter synthesis  

E-print Network

A General Filter Transfer Function Sensitivity with Respect to Integrator Magnitude and Phase Response 8 Sensitivity Theorems 85 86 VITA 90 LIST OF TABLES Table 1. Zero First-order Sensit1vity Des1gn Criteria Page 20 Zero F1rst... response at s/RC = 0. 05. Filter response at t/RC = 0. 10. Page 71 72 73 CHAPTER I INTRODUCTION I. Objective The objective of th1s thesis is to design improved 1ntegrators for use 1n active RC filters. To achieve this, zero sens1t1vity cr1ter1a...

Bailey, Glenn Roger

2012-06-07

387

Synthesis and in vitro antimalarial activity of sulfone endoperoxides.  

PubMed

A series of 4,8-dimethyl-4-phenylsulfonylmethyl-2,3-dioxabicyclo[3.3.1]+ ++nonanes, carrying a variety of substituents at position-8 (4) were prepared by a short and efficient method from R-(+)-limonene. Key reactions include thiol oxygen cooxidation, and alkylation and acylation of a sterically hindered tertiary alcohol compatible with the endoperoxy functionality. Some of compounds 4, which are structurally related to yingzhaosu A (2), were found to exhibit in vitro antimalarial activity comparable to that of artemisinin (1) and superior to that of arteflene (3). PMID:9871509

Bachi, M D; Korshin, E E; Ploypradith, P; Cumming, J N; Xie, S; Shapiro, T A; Posner, G H

1998-04-21

388

Synthesis, anticandidal activity and cytotoxicity of some tetrazole derivatives.  

PubMed

In this study, 14 different 2-[(1-methyl-1H-tetrazole-5-yl)thio]-1-(phenyl)ethanone derivatives (1-14) were synthesized. The structures of the obtained compounds were elucidated using IR, (1)H-NMR, (13)C-NMR and FAB(+)-MS spectral data and elemental analyses results. The compounds were screened for their anticandidal activity using the microbroth dilution method and for their cytotoxic effects using the MTT assay against NIH/3T3 cells. Some of the compounds were found to be potent anticandidal agents with weak cytotoxicities. PMID:23323990

Kaplancikli, Zafer Asim; Yurtta?, Leyla; Özdemir, Ahmet; Turan-Zitouni, Gülhan; I?can, Gökalp; Akal?n, Gül?en; Abu Mohsen, Usama

2014-02-01

389

2-Phenylaminonaphthoquinones and related compounds: synthesis, trypanocidal and cytotoxic activities.  

PubMed

A series of new 2-aminonaphthoquinones and related compounds were synthesized and evaluated in vitro as trypanocidal and cytotoxic agents. Some tested compounds inhibited epimastigote growth and trypomastigote viability. Several compounds showed similar or higher activity and selectivity as compared with current trypanocidal drug, nifurtimox. Compound 4l exhibit higher selectivity than nifurtimox against Trypanosoma cruzi in comparison with Vero cells. Some of the synthesized quinones were tested against cancer cells and normal fibroblasts, showing that certain chemical modifications on the naphthoquinone moiety induce and excellent increase the selectivity index of the cytotoxicity (4g and 10). The results presented here show that the anti-T. cruzi activity of 2-aminonaphthoquinones derivatives can be improved by the replacement of the benzene ring by a pyridine moiety. Interestingly, the presence of a chlorine atom at C-3 and a highly lipophilic alkyl group or aromatic ring are newly observed elements that should lead to the discovery of more selective cytotoxic and trypanocidal compounds. PMID:25127463

Sieveking, Ivan; Thomas, Pablo; Estévez, Juan C; Quiñones, Natalia; Cuéllar, Mauricio A; Villena, Juan; Espinosa-Bustos, Christian; Fierro, Angélica; Tapia, Ricardo A; Maya, Juan D; López-Muñoz, Rodrigo; Cassels, Bruce K; Estévez, Ramon J; Salas, Cristian O

2014-09-01

390

Green synthesis, spectroscopic investigation and photocatalytic activity of lead nanoparticles.  

PubMed

Most of researcher focused their research towards synthesize of nanoparticles by the method of applied chemical method which was one of the costliest method. We have focused cheapest and simplest method for the synthesizing of lead nanoparticles (Pb-NPs) using cocos nucifera L extract. The methanolic extract of cocos nucifera L was efficiently used as a reducing agent for synthesizing Pb-NPs. On treatment of lead acetate with cocos nucifera coir extracts, stable Pb-NPs were formed. The synthesized Pb-NPs were further confirmed by UV-visible spectroscopy, X-ray diffraction (XRD), Transmission electron microscope (TEM) and Energy Dispersive (EDAX) analysis. The secondary metabolites present in methanolic extract which can mainly act as a reducing and capping agents for the formation of Pb-NPs were identified by GC-MS. Anti-microbial activity for Pb-NPs against four pathogenic strain's such as Staphylococcus aureus, Escheria coli, Staphylococcus epidermis and Bacillus subtilis. Result states that Pb-NPs size was 47nm and also shows good activity against S. aureus. Further we report on photocatalytic absorption of malachite green dye processed in short UV wavelength at 254nm. UV spectral analysis showed peak absorbance at 613nm with special reference to the excitation of surfaces plasmon vibration by Pb-NPs. PMID:25574657

Elango, Ganesh; Roopan, Selvaraj Mohana

2015-03-15

391

Synthesis and catalytic activity of polysaccharide templated nanocrystalline sulfated zirconia  

SciTech Connect

Nanoscaled materials are of great interest due to their unique enhanced optical, electrical and magnetic properties. Sulfate-promoted zirconia has been shown to exhibit super acidic behavior and high activity for acid catalyzed reactions. Nanocrystalline zirconia was prepared in the presence of polysaccharide template by interaction between ZrOCl{sub 2}?8H{sub 2}O and chitosan template. The interaction was carried out in aqueous phase, followed by the removal of templates by calcination at optimum temperature and sulfation. The structural and textural features were characterized by powder XRD, TG, SEM and TEM. XRD patterns showed the peaks of the diffractogram were in agreement with the theoretical data of zirconia with the catalytically active tetragonal phase and average crystalline size of the particles was found to be 9 nm, which was confirmed by TEM. TPD using ammonia as probe, FTIR and BET surface area analysis were used for analyzing surface features like acidity and porosity. The BET surface area analysis showed the sample had moderately high surface area. FTIR was used to find the type species attached to the surface of zirconia. UV-DRS found the band gap of the zirconia was found to be 2.8 eV. The benzylation of o-xylene was carried out batchwise in atmospheric pressure and 433K temperature using sulfated zirconia as catalyst.

Sherly, K. B.; Rakesh, K. [Mahatma Gandhi University Regional Research Center in Chemistry, Department of Chemistry, Mar Athanasius College, Kothamangalam-686666, Kerala (India)

2014-01-28

392

Synthesis and cytotoxic activity of metallic complexes of lawsone.  

PubMed

In the present study, a series of metallic complexes of the 1,4-naphthoquinone lawsone (2-6) were synthesized and evaluated for potential cytotoxicity in a mouse leukemic macrophagic RAW 264.7 cell line. Cell viability was determined by the MTT assay. Significant growth inhibition was observed for the copper complex (4) with an IC(50) value of 2.5 ?M. This compound was selected for further evaluation of cytotoxic activity on several human cancer cells including HT-29 (human colorectal adenocarcinoma), HepG2 (human hepatocellular carcinoma) and HeLa, (human cervical adenocarcinoma cells). Significant cell viability decrease was also observed in HepG2 cells. The apoptotic potential of this complex was evaluated in these cells. Compound 4 induced apoptosis by a mechanism that involves the activation of caspases 3, 8 and 9 and modulation of apoptotic-related proteins such as Bax, Bad, and p53. These results indicate that metal complexes of lawsone derivatives, in particular compound 4, might be used for the design of new antitumoral agents. PMID:23545136

Oramas-Royo, Sandra; Torrejón, Concepción; Cuadrado, Irene; Hernández-Molina, Rita; Hortelano, Sonsoles; Estévez-Braun, Ana; de Las Heras, Beatriz

2013-05-01

393

Silk sericin-insulin bioconjugates: synthesis, characterization and biological activity.  

PubMed

When silk fiber derived from Bombyx mori was subjected to degumming treatments twice in water and subsequent degraded processing in slightly alkaline aqueous solution under high-temperature and high-pressure, the water-soluble silk sericin peptides (SS) with different molecular mass from 10 to 70 kDa were obtained. The sericin peptides could be conjugated covalently with insulin alone with cross-linking reagent glutaraldehyde. The physicochemical properties of the silk sericin-insulin (SS-Ins) conjugates were determined by Enzyme-Linked Immunosorbent Assay (ELISA). The biological activities of SS-Ins bioconjugates were investigated in vitro and in vivo. The results in human serum in vitro indicated that the half-life of the synthesized SS-Ins derivatives was 2.3 and 2.7 times more than that of bovine serum albumin-insulin (BSA-Ins) conjugates and intact insulin, respectively. The pharmacological activity of SS-Ins bioconjugates lengthened to 21 h in mice in vivo, which was over 4 times longer than that of the native insulin. The immunogenicity of silk sericin and the antigenicity of SS-Ins derivatives were not observed in both rabbits and mice. The bioconjugation of insulin with silk sericin protein evidently improved both physicochemical and biological stability of the polypeptide. PMID:17034892

Zhang, Yu-Qing; Ma, Yan; Xia, Yun-Yue; Shen, Wei-De; Mao, Jian-Ping; Xue, Ren-Yu

2006-10-27

394

Synthesis, biological activity and molecular modeling studies of novel COX-1 inhibitors.  

PubMed

Synthesis of new potential COX-1 and/or COX-2 inhibitors, derivatives of 1,1-di-(3-carboxyphenyl)ethane, their biological activity, docking results on COX-1 enzyme and absorption, distribution, metabolism, excretion (ADME) properties are presented. In addition to known interactions between ketoprofen and ibuprofen, leading NSAID agents and COX-1 active site, the possibility of formation of additional interactions is explored. Interactions with Ala527, and with one of the water molecules situated within the active site are identified. Molecular mechanics and DFT calculations for studied compounds have revealed free rotation around two central bonds (C1-C3' and C1-C3"), making them flexible, thus easier to enter and adjust to the active site. Further modifications of core structure have been undertaken to optimize biological activity and ADME properties. As a result, two of the compounds are indicated as novel COX-1 inhibitors. PMID:14987823

Marti?, Miljen; Tati?, Iva; Markovi?, Stribor; Kujundzi?, Nedjeljko; Kostrun, Sanja

2004-02-01

395

FGF19 as a Postprandial, Insulin-Independent Activator of Hepatic Protein and Glycogen Synthesis  

PubMed Central

Fibroblast growth factor (FGF) 19 is an enterokine synthesized and released when bile acids are taken up into the ileum. We show that FGF19 stimulates hepatic protein and glycogen synthesis but does not induce lipogenesis. The effects of FGF19 are independent of the activity of either insulin or the protein kinase Akt and, instead, are mediated through a mitogen-activated protein kinase signaling pathway that activates components of the protein translation machinery and stimulates glycogen synthase activity. Mice lacking FGF15 (the mouse FGF19 ortholog) fail to properly maintain blood concentrations of glucose and normal postprandial amounts of liver glycogen. FGF19 treatment restored the loss of glycogen in diabetic animals lacking insulin. Thus, FGF19 activates a physiologically important, insulin-independent endocrine pathway that regulates hepatic protein and glycogen metabolism. PMID:21436455

Kir, Serkan; Beddow, Sara A.; Samuel, Varman T.; Miller, Paul; Previs, Stephen F.; Suino-Powell, Kelly; Xu, H. Eric; Shulman, Gerald I.; Kliewer, Steven A.; Mangelsdorf, David J.

2011-01-01

396

Synthesis and Biological Characterization of Protease-Activated Prodrugs of Doxazolidine  

PubMed Central

Doxazolidine (doxaz) is a new anthracycline anticancer agent. While structurally similar to doxorubicin (dox), doxaz acts via a distinct mechanism to selectively enhance anticancer activity over cardiotoxicity, the most significant clinical impediment to successful anthracycline treatment. Here, we describe the synthesis and characterization of a prodrug platform designed for doxaz release mediated by secreted proteolytic activity, a common association with invasiveness and poor prognosis in cancer patients. GaFK-Doxaz is hydrolysable by the proteases plasmin and cathepsin B, both strongly linked with cancer progression, as well as trypsin. We demonstrate that activation of GaFK-Doxaz releases highly potent doxaz which powerfully inhibits the growth of a wide variety of cancer cells (average IC50: 8 nM). GaFK-Doxaz is stable in human plasma and is poorly membrane permeable, thereby limiting activation to locally-secreted proteolytic activity and reducing the likelihood of severe side effects. PMID:22742660

Barthel, Benjamin L.; Rudnicki, Daniel L.; Kirby, Thomas Price; Colvin, Sean M.; Burkhart, David J.; Koch, Tad H.

2012-01-01

397

Synthesis, characterization and biological activity of dimethyltin dicarboxylates containing germanium.  

PubMed

A series of diorganotin dicarboxylates of the general formula (CH(3))(2)Sn(OCOCHR(3)CHR(2)GeR(1))(2) where R(1)=(C(6)H(5))(3), (P-CH(3)C(6)H(4))3, N(CH(2)CH(2)O)(3), R(2)=C(6)H(5), H, CH(3), P-CH(3)OC(6)H(4), P-ClC(6)H(4), P-CH(3)C(6)H(4), R(3)=CH(3) and H, have been synthesized by the reaction of dimethyltin oxide with germanium substituted propionic acid in 1:2 molar ratio in toluene. The H(2)O formed was removed azeotropically using a Dean and Stark apparatus. All the compounds have been characterized by IR, multinuclear ((1)H, (13)C, (119)Sn) NMR, mass and Mössbauer spectroscopies. All compounds were found to have potential activity against bacteria. PMID:18476006

Choudhary, M A; Mazhar, M; Ali, S; Song, X; Eng, G

2002-01-01

398

Synthesis and pharmacological activity of the metabolites of Pratosartan.  

PubMed

Three hydroxylated metabolites of 2-propyl-3-[2'-(1H-tetrazol-5-yl)biphenyl-4-ylmethyl]-5,6,7,8-tetrahydro-3H-cycloheptimidazol-4-one (Pratosartan), which is a selective angiotensin II receptor antagonist, were synthesized in confirmation of their structures and in studies of their pharmacological properties. An MTPA ester of the human main metabolite was identified with the synthesized compound by comparing (1)H-NMR spectra, MS spectra, and HPLC retention time. The structure of the human main metabolite was confirmed to be (S)-(-)-2-(1-hydroxypropyl)-3-[2'-(1H-tetrazol-5-yl)biphenyl-4-ylmethyl]-5,6,7,8-tetrahydro-3H-cycloheptimidazol-4-one ((S)-(-)-1). Also, the rat main metabolites were confirmed to be 8-hydroxylated compound (2) and 5-hydroxylated compound (3). These metabolites showed lower antagonistic activity than that of the parent compound. PMID:16755044

Sonegawa, Motoharu; Suzaka, Hiroaki; Tomiyama, Akira; Tomiyama, Tsuyoshi

2006-06-01

399

Synthesis and anticancer activity of novel quinoline-docetaxel analogues.  

PubMed

A series of novel quinoline-docetaxel analogues (6a-6g, 13a-13g) were designed and synthesized by introducing bioactive quinoline scaffold to C2'-OH of docetaxel. The anticancer activities of these novel analogues were investigated against different human cancer cell lines including Hela, A549, A2780, MCF-7 and two resistant strains A2780-MDR and MCF-7-MDR. The data showed these analogues possessed similar to better cytotoxicity than docetaxel. Compound 6c was found to be the most potent one, and its IC50 value against MCF-7-MDR was 8.8 nM (IC50 of docetaxel was 180 nM). The work indicated that the introduction of quinolyl group in docetaxel could enhance cytotoxicity and reduce drug-resistance. PMID:24835987

Chen, Ming; Chen, Hui; Ma, Jiangwei; Liu, Xueying; Zhang, Shengyong

2014-07-01

400

Synthesis, characterization and SERS activity of biosynthesized silver nanoparticles  

NASA Astrophysics Data System (ADS)

Silver nanoparticles were rapidly synthesized using Moringa oleifera flower extract as the reducing agent shows surface plasmon resonance peak at 439 nm. The size and shape of the nanoparticles controlled by varying the concentration of M. oleifera flower extract in the reaction medium. The synthesized silver nanoparticles were well-dispersed spherical nanoparticles with the average size of 14 nm. The retinoic acid present in M. oleifera flower extract used as reducing agent and proteins was responsible for capping of the bioreduced silver nanoparticles. The obtained nanoparticle shows size-dependent SERS activity. The SERS spectrum indicates that the pyridine adsorbed on the silver surface in a stand-on orientation via its nitrogen lone pair electrons.

Bindhu, M. R.; Sathe, V.; Umadevi, M.

2013-11-01

401

Synthesis, characterization and SERS activity of biosynthesized silver nanoparticles.  

PubMed

Silver nanoparticles were rapidly synthesized using Moringa oleifera flower extract as the reducing agent shows surface plasmon resonance peak at 439nm. The size and shape of the nanoparticles controlled by varying the concentration of M. oleifera flower extract in the reaction medium. The synthesized silver nanoparticles were well-dispersed spherical nanoparticles with the average size of 14nm. The retinoic acid present in M. oleifera flower extract used as reducing agent and proteins was responsible for capping of the bioreduced silver nanoparticles. The obtained nanoparticle shows size-dependent SERS activity. The SERS spectrum indicates that the pyridine adsorbed on the silver surface in a stand-on orientation via its nitrogen lone pair electrons. PMID:23867642

Bindhu, M R; Sathe, V; Umadevi, M

2013-11-01

402

Synthesis, characterization, and anticancer activity of ruthenium-pyrazole complexes.  

PubMed

A series of new water soluble Ru(III) pyrazole complexes mer-[RuCl(3)(DMSO-S)(pyz)(2)] 1, mer-[RuCl(3)(DMSO-S)(DMSO-O)(pyz)] 2, mer-[RuCl(3)(bpy)(dmpyz)] 3, and mer-[RuCl(3)(DMSO-S)(dmpyz)(2)] 4 (pyz=pyrazole; dmpyz=3,5-dimethylpyrazole, bpy=2,2'-bipyridine) have been synthesized and characterized by use of a combination of spectroscopy (IR and UV-visible), X-ray diffraction, and cyclic voltammetry. The molecular X-ray structure of all reported compounds (1-4) revealed distorted octahedral coordination around ruthenium. The cytotoxicity assay on human breast cancer cells (MCF7) demonstrated that compounds 1 and 4 affect cell viability, whereas compounds 2 and 3 do not show appreciable activity. The IC(50) values for 1 and 4 lie within the range of 71-32?M in MCF7 cells. PMID:22484498

David, Solene; Perkins, Richard S; Fronczek, Frank R; Kasiri, Sahba; Mandal, Subhrangsu S; Srivastava, Radhey S

2012-06-01

403

Synthesis of Silver Polymer Nanocomposites and Their Antibacterial Activity  

NASA Astrophysics Data System (ADS)

PVA (Polyvinyl Alcohol) silver nanocomposites of different sizes were prepared by chemical reduction method. Silver nitrate was taken as the metal precursor and amine hydrazine as a reducing agent. The formation of the silver nanoparticles was noticed using UV- visible absorption spectroscopy. The UV-visible spectroscopy revealed the formation of silver nanoparticles by exhibiting the surface plasmon resonance. The bactericidal activity due to silver release from the surface was determined by the modification of conventional diffusion method. Salmonella typhimurium, Serratia sps and Shigella sps were used as test bacteria which are gram-negative type bacteria. Effect of the different sizes of silver nano particles on antibacterial efficiency was discussed. Zones of inhibition were measured after 24 hours of incubation at 37 °C which gave 20 mm radius for high concentration of silver nanoparticles.

Gavade, Chaitali; Shah, Sunil; Singh, N. L.

2011-07-01

404

Sulfation of tea polysaccharides: synthesis, characterization and hypoglycemic activity.  

PubMed

Neutral polysaccharides (NTPS) and acid polysaccharides (ATPS) from tea leaves were obtained on a D315 macroporous anion-exchange resin column chromatography. NTPS and ATPS were sulfated by the pyridine-sulfonic acid method to obtain NTPS-S and ATPS-S. It was found that NTPS was easier sulfated than ATPS. There are strong characteristic absorption peaks located in 1258 cm(-1), 1146 cm(-1), 832 cm(-1) and 617 cm(-1) in the FTIR spectra of sulfated polysaccharides. Sulfation of polysaccharides also affected the endothermic and exothermic peaks via the DSC scan analysis. The appearance of exothermic peaks in both NTPS-S and ATPS-S indicated that the redox reaction might happen. The comparative study of hypoglycemic effect on mice showed that the sulfation of polysaccharides significantly improved hypoglycemic activity. PMID:20026346

Wang, Yuanfeng; Peng, Yonghua; Wei, Xinlin; Yang, Zhiwei; Xiao, Jianbo; Jin, Zhengyu

2010-03-01

405

Synthesis and folding of a mirror-image enzyme reveals ambidextrous chaperone activity  

PubMed Central

Mirror-image proteins (composed of d-amino acids) are promising therapeutic agents and drug discovery tools, but as synthesis of larger d-proteins becomes feasible, a major anticipated challenge is the folding of these proteins into their active conformations. In vivo, many large and/or complex proteins require chaperones like GroEL/ES to prevent misfolding and produce functional protein. The ability of chaperones to fold d-proteins is unknown. Here we examine the ability of GroEL/ES to fold a synthetic d-protein. We report the total chemical synthesis of a 312-residue GroEL/ES-dependent protein, DapA, in both l- and d-chiralities, the longest fully synthetic proteins yet reported. Impressively, GroEL/ES folds both l- and d-DapA. This work extends the limits of chemical protein synthesis, reveals ambidextrous GroEL/ES folding activity, and provides a valuable tool to fold d-proteins for drug development and mirror-image synthetic biology applications. PMID:25071217

Weinstock, Matthew T.; Jacobsen, Michael T.; Kay, Michael S.

2014-01-01

406

Reaction synthesis of intermetallics  

SciTech Connect

Exothermicity associated with the synthesis of aluminides was utilized to obtain nickel, iron, and cobalt aluminides. Combustion synthesis, extrusion, and hot pressing were utilized to obtain intermetallics and their composites. Extrusion conditions, reduction ratios, and hot-pressing conditions of the intermetallics and their composites are discussed.

Deevi, S.C.; Sikka, V.K.

1994-12-31

407

Breaking Up with Combustion  

NSDL National Science Digital Library

This activity teaches combustion as the interaction of a fuel source and oxygen. A burning candle is observed, then extinguished—first by a glass cup placed over it to cut off the oxygen supply, then using carbon dioxide generated by vinegar and baking soda. Some background information is provided about how car engines use gasoline as fuel, and how humans use food as fuel— both are similar to how the candle uses wax as fuel. The activity is written for a kit that can be checked out of the library, but the kit is not required.

2012-06-26

408

Synthesis and polymorphic control for visible light active titania nanoparticles  

NASA Astrophysics Data System (ADS)

Titania (TiO2) is useful for many applications in photocatalysis, antimicrobials, pigment, deodorization, and decomposition of harmful organics and undesirable compounds in the air and waste water under UV irradiation. Among the three phases of TiO2, Rutile, Anatase, and Brookite, studies have been more focused on the anatase and rutile phases. Pure brookite is the most difficult phase to prepare, even under hydrothermal conditions. Predominantly brookite phase TiO2 nanoparticles were prepared by the Water-based Ambient Condition Sol (WACS) process in our laboratory. The objectives of this research were to enhance visible light active (VLA) photocatalytic properties of polymorphic brookite TiO2 by minimizing the lattice defects and narrowing band gap of titania by nitrogen and/or carbon chromophone, and to investigate the deactivation, reusability, and regeneration of the VLA titania in order to design better titania catalysts for organic compound degradation applications. In order to study the influence of hydroxyl content on photocatalytic activities (PCAs) of polymorphic titania nanoparticles, the WACS samples were post-treated by a Solvent-based Ambient Condition Sol (SACS) process in sec-butanol (sec-BuOH). All samples were characterized for phase composition, surface area, hydroxyl contamination, and particle morphology by x-ray diffraction, N2 physisorption, FT-IR, solid state 1H NMR and scanning electron microscopy, and then compared to a commercial titania, Degussa P25. Evaluation of methyl orange (MO) degradation under UV irradiation results showed that the lower lattice hydroxyl content in SACS titania enhanced the PCA. As-prepared titania and SACS samples, which have similar surface areas and crystallinity, were compared in order to prove that the superior PCA came from the reduction in the lattice hydroxyl content. To enhance PCA and VLA properties of WACS, an alternative high boiling point polar solvent, N-methylpyrrolidone (NMP), was utilized in the SACS process at a higher treatment temperature to modify polymorphic titania nanoparticles. This SACS sample was called "SACS-NMP". SACS, using NMP as the solvent, could also extract lattice hydroxyls, and decorate nitrogen on the titania surface. The PCA of SACS-NMP was superior to that of SACS-sec-BuOH. Nitrogen incorporation of SACS-NMP titania was investigated by CHN analysis and x-ray photoelectron spectroscopy (XPS). VL absorbance for all samples was characterized by UV-Vis absorption spectrophotometry. PCA of MO degradation under UV and VL showed that SACS-NMP is a powerful treatment to enhance PCA by minimizing lattice hydroxyls and doping the titania surface with nitrogen. The effect of calcination conditions on SACS-NMP samples was also studied. The calcination conditions, especially the temperature and calcination atmosphere, have an influence on the BET surface area, crystallite size, titania phase content, and PCA under VL irradiation. SACS-NMP samples calcined in air at 200°C for 2 hours showed the best VL activated photocatalytic performance in this research. Additionally, the SACS-NMP sample exhibited superior VL properties to several available reference anatase titania samples. This could be explained as the effective charge separation by the intercrystalline electron transport from brookite to anatase grains complemented by strong VL absorption by the nitrogen species in NMP. The deactivation and regeneration of the VLA titania were investigated and compared to a commercial titania, Kronos VLP7000. PCA of the titania under VL for MO decolorization gradually decreased with increasing testing time and the number of runs. The cause of the deactivation was identified as the deposition of the decomposed MO or the carbonaceous deposit. Among the possible regeneration procedures for used SACS-NMP samples, methanol washing was shown to be the most effective up to ˜80% of the PCA recovery. Accordingly, the SACS-NMP samples could not be completely recovered since a regeneration process would possibly remove some of nitrogen species responsib

Kaewgun, Sujaree

409

Synthesis of monodispersed silver nanoparticles using Hibiscus cannabinus leaf extract and its antimicrobial activity.  

PubMed

Synthesis of silver nanoparticles using leaf extract of Hibiscus cannabinus has been investigated. The influences of different concentration of H. cannabinus leaf extract, different metal ion concentration and different reaction time on the above cases on the synthesis of nanoparticles were evaluated. The synthesized nanoparticles were characterized using UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The prepared silver nanoparticles were monodispersed, spherical in shape with the average particle size of 9 nm and shows surface plasmon peak at 446 nm. The study also reveals that the ascorbic acid present in H. cannabinus leaf extract has been used as reducing agent. The prepared silver nanoparticle shows good antimicrobial activity against Escherichia coli, Proteus mirabilis and Shigella flexneri. PMID:23103459

Bindhu, M R; Umadevi, M

2013-01-15

410

Efficient synthesis of silver nanoparticles from Prosopis juliflora leaf extract and its antimicrobial activity using sewage  

NASA Astrophysics Data System (ADS)

In this paper, aqueous extract of fresh leaves of Prosopis juliflora was used for the synthesis of silver (Ag) nanoparticles. UV-Vis spectroscopy studies were carried out to asses silver nanoparticles formation within 5 min, scanning electron microscopic was used to characterize shape of the Ag nanoparticles, X-ray diffraction analysis confirms the nanoparticles as crystalline silver and facecentered cubic type and Fourier transform infra-red assed that shows biomolecule compounds which are responsible for reduction and capping material of silver nanoparticles. The anti microbial activity of silver nanoparticle was performed using sewage. The approach of plant-mediated synthesis appears to be cost efficient, eco-friendly and easy methods.

Raja, K.; Saravanakumar, A.; Vijayakumar, R.

2012-11-01

411

Synthesis of gold nanoparticles using renewable Punica granatum juice and study of its catalytic activity  

NASA Astrophysics Data System (ADS)

Punica granatum juice, a delicious multivitamin drink of great medicinal significance, is rich in different types of phytochemicals, such as terpenoids, alkaloids, sterols, polyphenols, sugars, fatty acids, aromatic compounds, amino acids, tocopherols, etc. We have demonstrated the use of the juice for the synthesis of gold nanoparticles (AuNPs) at room temperature under very mild conditions. The synthesis of the AuNPs was complete in few minutes and no extra stabilizing or capping agents were necessary. The size of the nanoparticles could be controlled by varying the concentration of the fruit extract. The AuNPs were characterized by surface plasmon resonance spectroscopy, high resolution transmission electron microscopy, fourier transform infrared spectroscopy and X-ray diffraction studies. Catalytic activity of the synthesized colloidal AuNPs has also been demonstrated.

Dash, Shib Shankar; Bag, Braja Gopal

2014-01-01

412

Developing novel organocatalyzed aldol reactions for the enantioselective synthesis of biologically active molecules  

PubMed Central

Aldol reaction is one of the most important methods for the formation of carbon-carbon bonds. Because of its significance and usefulness, asymmetric versions of this reaction have been realized with different approaches in the past. Over the last decade, the area of organocatalysis has made significant progresses. As one of most studied reactions in organocatalyses, organocatalyzed aldol reaction has emerged as a powerful tool for the synthesis of a large number of useful products in optically enriched forms. In this review, we summarize our efforts on the development of novel organocatalyzed aldol reactions for the enantioselective synthesis of biological active molecules. Literatures closely related to our studies are also covered. PMID:21918584

Bhanushali, Mayur; Zhao, Cong-Gui

2011-01-01

413

Synthesis of monodispersed silver nanoparticles using Hibiscus cannabinus leaf extract and its antimicrobial activity  

NASA Astrophysics Data System (ADS)

Synthesis of silver nanoparticles using leaf extract of Hibiscus cannabinus has been investigated. The influences of different concentration of H. cannabinus leaf extract, different metal ion concentration and different reaction time on the above cases on the synthesis of nanoparticles were evaluated. The synthesized nanoparticles were characterized using UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The prepared silver nanoparticles were monodispersed, spherical in shape with the average particle size of 9 nm and shows surface plasmon peak at 446 nm. The study also reveals that the ascorbic acid present in H. cannabinus leaf extract has been used as reducing agent. The prepared silver nanoparticle shows good antimicrobial activity against Escherichia coli, Proteus mirabilis and Shigella flexneri.

Bindhu, M. R.; Umadevi, M.

2013-01-01

414

Coleus aromaticus leaf extract mediated synthesis of silver nanoparticles and its bactericidal activity  

NASA Astrophysics Data System (ADS)

The utilization of various plant resources for the biosynthesis of metallic nanoparticles is called green nanotechnology, and it does not utilize any harmful chemical protocols. The present study reports the plant-mediated synthesis of silver nanoparticles using the plant leaf extract of Coleus aromaticus, which acts as a reducing and capping agent. The silver nanoparticles were characterized by ultraviolet visible spectroscopy, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and the size of the silver nanoparticles is 44 nm. The bactericidal activity of the silver nanoparticles was carried out by disc diffusion method that showed high toxicity against Bacillus subtilis and Klebsiella planticola. Biosynthesis of silver nanoparticles by using plant resources is an eco-friendly, reliable process and suitable for large-scale production. Moreover, it is easy to handle and a rapid process when compared to chemical, physical, and microbe-mediated synthesis process.

Vanaja, Mahendran; Annadurai, Gurusamy

2013-06-01

415

Flutter suppression control law synthesis for the Active Flexible Wing model  

NASA Technical Reports Server (NTRS)

The Active Flexible Wing Project is a collaborative effort between the NASA Langley Research Center and Rockwell International. The objectives are the validation of methodologies associated with mathematical modeling, flutter suppression control law development and digital implementation of the control system for application to flexible aircraft. A flutter suppression control law synthesis for this project is described. The state-space mathematical model used for the synthesis included ten flexible modes, four control surface modes and rational function approximation of the doublet-lattice unsteady aerodynamics. The design steps involved developing the full-order optimal control laws, reducing the order of the control law, and optimizing the reduced-order control law in both the continuous and the discrete domains to minimize stochastic response. System robustness was improved using singular value constraints. An 8th order robust control law was designed to increase the symmetric flutter dynamic pressure by 100 percent. Preliminary results are provided and experiences gained are discussed.

Mukhopadhyay, Vivek; Perry, Boyd, III; Noll, Thomas E.

1989-01-01

416

Total synthesis and absolute configuration assignment of MRSA active garcinol and isogarcinol.  

PubMed

A short total synthesis of (±)-garcinol and (±)-isogarcinol, two endo-type?B PPAPs with reported activity against methiciline resistant Staphylococcus aureus (MRSA), is presented. The separation of framework-constructing from framework-decorating steps and the application of two highly regio- and stereoselective Pd-catalysed allylations, that is, the Pd-catalysed decarboxylative Tsuji-Trost allylation and the diastereoselective Pd-catalysed allyl-allyl cross-coupling, are key elements that allowed the total synthesis to be accomplished within 13 steps starting from acetylacetone. After separation of the enantiomers the absolute configurations of the four natural products (i.e., (-)-garcinol, (+)-guttiferone?E (i.e., ent-garcinol), (-)-isogarcinol, and (+)-isoxanthochymol (i.e., ent-isogarcinol)) were assigned based on ECD spectroscopy. PMID:25537962

Socolsky, Cecilia; Plietker, Bernd

2015-02-01

417

Chemical synthesis of ?-secretase activating protein using pseudoglutamines as ligation sites.  

PubMed

The chemical synthesis of analogue of a novel ?-secretase activating protein, which may play a pivotal role in the formation of amyloid peptides, the precursor to Alzheimer's disease, is described. The linear polypeptide sequence, consisting of 121 amino acids was assembled from four unprotected peptide building blocks using a convergent ligation-based synthesis. A strategic mutation of three glutamine residues to cysteine enabled the ligations, and the cysteines were subsequently converted to pseudoglutamines, to mimic the native glutamine. The full length unfolded protein was obtained in milligram amounts and was demonstrated to be homogeneous by liquid chromatography and mass spectrometry. © 2014 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 104: 37-45, 2015. PMID:25523549

Harris, Paul W R; Squire, Chris; Young, Paul G; Brimble, Margaret A

2015-01-01

418

Synthesis, biological activity and structure-activity relationship of 4,5-dimethoxybenzene derivatives inhibitor of rhinovirus 14 infection.  

PubMed

Human rhinoviruses are a common cause of respiratory infections, and thus constitute an important target for medicinal chemistry. Still, no drug has been approved for clinical use. We report herein the discovery of dibenzenic derivatives with potent and specific in vitro anti-rhinoviral 14 activity. A total of 99 structural analogues were synthesized by an original synthesis method, i.e. through one organic agent Tetrakis(DimethylAmino)Ethylene (TDAE) and a structure-activity relationship was established. It was shown that 4,5-dimethoxy scaffold and the presence of a C-4 substituted aromatic moiety were necessary to the in vitro activity of these original agents. However, modifications on liker were not convincing. The benzonitrile derivative 23 was identified as the most potent and selective inhibitor of rhinovirus replication in these series (EC?? of 2 ± 0.5 ?M, CC?? of 184 ?M, selectivity index of 92). PMID:24602790

Roche, Manon; Lacroix, Céline; Khoumeri, Omar; Franco, David; Neyts, Johan; Terme, Thierry; Leyssen, Pieter; Vanelle, Patrice

2014-04-01

419

Synthesis and antiprotozoal activities of benzyl phenyl ether diamidine derivatives.  

PubMed

Sixty-two cationic benzyl phenyl ether derivatives (36 amidines and 26 prodrugs) were prepared and assayed for activities in vitro and in vivo against Trypanosoma brucei rhodesiense (STIB900), and in vitro against Plasmodium falciparum (K1) and Leishmania donovani axenic amastigotes. 3-Amidinobenzyl 4-amidino-2-iodo-6-methoxyphenyl ether dihydrochloride (55, IC50 = 3.0 nM) and seven other compounds exhibited IC50 values below 10 nM against T. b. rhodesiense in vitro. The 2-bromo-4,4'-diamidino analogue 19 (IC50 = 4.0 nM) and 12 other analogues were more potent than pentamidine (IC50 = 46 nM) against P. falciparum. The 3',4-diamidino-2,6-diiodo analogue 49 (IC50 = 1.4 ?M) and two other compounds were more effective than pentamidine (IC50 = 1.8 ?M) against L. donovani. A prodrug, 3',4-bis(N?-methoxy)amidino-2-bromo derivative 38, was the most efficacious against trypanosome infected mice, attaining 4/4 cures in four daily 25 mg/kg oral doses, and the 2-chloro-4,4'-diamidine 18 cured 3/4 mice in four daily 5 mg/kg intraperitoneal doses. PMID:23871911

Patrick, Donald A; Bakunov, Stanislav A; Bakunova, Svetlana M; Jones, Susan Kilgore; Wenzler, Tanja; Barszcz, Todd; Kumar, Arvind; Boykin, David W; Werbovetz, Karl A; Brun, Reto; Tidwell, Richard R

2013-09-01

420

Synthesis and Anti-Trypanosoma cruzi Activity of Diaryldiazepines.  

PubMed

Chagas disease is a so-called "neglected disease" and endemic to Latin America. Nifurtimox and benznidazole are drugs that have considerable efficacy in the treatment of the acute phase of the disease but cause many significant side effects. Furthermore, in the Chronic Phase its efficiency is reduced and their therapeutic effectiveness is dependent on the type of T. cruzi strain. For this reason, the present work aims to drive basic research towards the discovery of new chemical entities to treat Chagas disease. Differently substituted 5,7-diaryl-2,3-dihydro-1,4-diazepines were synthesized by cyclocondensation of substituted flavones with ethylenediamine and tested as anti-Trypanosoma cruzi candidates. Epimastigotes of the Y strain from T. cruzi were used in this study and the number of parasites was determined in a Neubauer chamber. The most potent diaryldiazepine that reduced epimastigote proliferation exhibited an IC50 value of 0.25 ?M, which is significantly more active than benznidazole. PMID:25546620

Menezes, Júlio César L; Vaz, Luana Beatriz A; de Abreu Vieira, Paula Melo; da Silva Fonseca, Kátia; Carneiro, Cláudia Martins; Taylor, Jason G

2014-01-01

421

One-step solution combustion synthesis of cobalt-nickel oxides/C/Ni/CNTs nanocomposites as electrochemical capacitors electrode materials  

NASA Astrophysics Data System (ADS)

With Co(NO3)2·6H2O (oxidizer and Co source), Ni(NO3)2·6H2O (oxidizer and Ni source) and citric acid (fuel) as starting materials, cobalt-nickel oxides/C/Ni ternary nanocomposites have been synthesized by a scalable, one-step solution combustion process at only 300 °C within 30 min in air. In these composites, the metallic nickel and amorphous carbon (conductive phases) were in situ formed by the reduction of Ni2+ and carbonization of the excess citric acid during combustion, respectively. Experimental results indicated that the fuel:oxidant and Co:Ni molar ratios in precursor solution showed strong influences on the phase composition, morphology and electrochemical performance of products. With the increase of the fuel dosage, the products transformed from well-crystallized cubic NiO/Ni to Ni (nickel-related phases), then to relatively amorphous Ni/NiO and finally NiO. Electrochemical tests indicated that the optimized product showed a high specific capacitance of 446 F g-1 at 1 A g-1 (or 280 F g-1 at 10 A g-1) with a Co:Ni:C6H8O7 molar ratio of 4:5:86/9. Significantly, besides its mild experimental conditions, the method could be used to prepare cobalt-nickel oxides/C/Ni/CNTs quarternary nanocomposites by simply adding acid-treated CNTs into precursor combustion solution. Thanks to the high electrical conduction of CNTs, the specific capacitance could be further improved up to 579 F g-1 at 1 A g-1, or 350 F g-1 at 10 A g-1.

Kang, Litao; Deng, Jiachun; Liu, Tiejun; Cui, Mangwei; Zhang, Xinyu; Li, Peiyang; Li, Ying; Liu, Xuguang; Liang, Wei

2015-02-01

422

Surfactant-Assisted Sol-Gel Auto-Combustion Synthesis of Sr-Hexaferrite Nano-Crystalline Powder Using Different Fuels and Basic Agents  

NASA Astrophysics Data System (ADS)

In this research Sr-hexaferrite powder was synthesized by a sol-gel auto-combustion route using two different fuels (glycine and citric acid) and two different basic agents (ammonia and trimethylamine). N-decyltrimethylammonium bromide (C13H30BrN) was also employed as a cationic surfactant. The results showed the finest crystallite size and the lowest calcination temperature have been obtained as 27.2 nm and 800° C respectively, in the presence of citric acid, trimethylamine and surfactant.

Ebrahimi, S. A. S.; Hasab, M. G.; Badiei, A.

2010-03-01

423

Surfactant-Assisted Sol-Gel Auto-Combustion Synthesis of SR-HEXAFERRITE Nanopowder Using Different Fuels and Basic Agents  

NASA Astrophysics Data System (ADS)

In this research Sr-hexaferrite powder was synthesized by a sol-gel auto-combustion route using two different fuels (glycine and citric acid) and two different basic agents (ammonia and trimethylamine). N-decyltrimethylammonium bromide (C13H30BrN) was also employed as a cationic surfactant. The results showed the finest crystallite size and the lowest calcination temperature have been obtained as 27.2 nm and 800 °C respectively, in the presence of citric acid, trimethylamine and surfactant.

Ghobeiti Hassab, M.; Seyyed Ebrahimi, S. A.; Dehghan, R.

424

Synthesis and Magnetic Property of Co0.5Zn0.5Fe2O4 Nanoparticles by Template-Assisted Combustion Method  

Microsoft Academic Search

In the present article, zinc cobalt ferrite (Co0.5Zn0.5Fe2O4) nanopowders were synthesized by a template-assisted citric combustion method. Polyethylene Glycol (PEG-4000) and carboxymethyl cellulose (CMC) were used as the templating agents for controlling the anisotropy and the microstructure of the Co0.5Zn0.5Fe2O4 nanopowder. The synthesized nanopowders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and a vibrating sample magnetometer (VSM).

H. Y. He

2011-01-01

425

Synthesis and Magnetic Properties of Co0.5Zn0.5Fe2O4 Nanoparticles by Template-Assisted Combustion Method  

Microsoft Academic Search

In the present article, zinc cobalt ferrite (Co0.5Zn0.5Fe2O4) nanopowders were synthesized by a template-assisted citric combustion method. Polyethylene Glycol (PEG-4000) and carboxymethyl cellulose (CMC) were used as the templating agents for controlling the anisotropy and the microstructure of the Co0.5Zn0.5Fe2O4 nanopowder. The synthesized nanopowders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and a vibrating sample magnetometer (VSM).

H. Y. He

2012-01-01

426

Regulation of glutamine synthetase activity and synthesis in free-living and symbiotic Anabaena spp.  

PubMed Central

Regulation of the synthesis and activity of glutamine synthetase (GS) in the cyanobacterium Anabaena sp. strain 7120 was studied by determining GS transferase activity and GS antigen concentration under a variety of conditions. Extracts prepared from cells growing exponentially on a medium supplemented with combined nitrogen had a GS activity of 17 mumol of gamma-glutamyl transferase activity per min per mg of protein at 37 degrees C. This activity doubled in 12 h after transfer of cells to a nitrogen-free medium, corresponding to the time required for heterocyst differentiation and the start of nitrogen fixation. Addition of NH3 to a culture 11 h after an inducing transfer immediately blocked the increase in GS activity. In the Enterobacteriaceae, addition of NH3 after induction results in the covalent modification of GS by adenylylation. The GS of Anabaena is not adenylylated by such a protocol, as shown by the resistance of the transferase activity of the enzyme to inhibition by Mg2+ and by the failure of the enzyme to incorporate 32P after NH3 upshift. Methionine sulfoximine inhibited Anabaena GS activity rapidly and irreversibly in vivo. After the addition of methionine sulfoximine to Anabaena, the level of GS antigen neither increased nor decreased, indicating that Glutamine cannot be the only small molecule capable of regulating GS synthesis. Methionine sulfoximine permitted heterocyst differentiation and nitrogenase induction to escape repression by NH3. Nitrogen-fixing cultures treated with methionine sulfoximine excreted NH3. The fern Azolla caroliniana contains an Anabaena species living in symbiotic association. The Anabaena species carries out nitrogen fixation sufficient to satisfy all of the combined nitrogen requirements of the host fern. Experiments by other workers have shown that the activity of GS in the symbiont is significantly lower than the activity of GS in free-living Anabaena. Using a sensitive radioimmune assay and a normalization procedure based on the content of diaminopimelic acid, a component unique to the symbiont, we found that the level of GS antigen in the symbiont was about 5% of the level in free-living Anabaena cells. Thus, the host fern appears to repress synthesis of Anabaena GS in the symbiotic association. Images PMID:6127334

Orr, J; Haselkorn, R

1982-01-01

427

Combustion chemistry  

SciTech Connect

This research is concerned with the development and use of sensitivity analysis tools to probe the response of dependent variables to model input variables. Sensitivity analysis is important at all levels of combustion modeling. This group`s research continues to be focused on elucidating the interrelationship between features in the underlying potential energy surface (obtained from ab initio quantum chemistry calculations) and their responses in the quantum dynamics, e.g., reactive transition probabilities, cross sections, and thermal rate coefficients. The goals of this research are: (i) to provide feedback information to quantum chemists in their potential surface refinement efforts, and (ii) to gain a better understanding of how various regions in the potential influence the dynamics. These investigations are carried out with the methodology of quantum functional sensitivity analysis (QFSA).

Brown, N.J. [Lawrence Berkeley Laboratory, CA (United States)

1993-12-01

428

Enantioselective synthesis of tatanans A–C and reinvestigation of their glucokinase-activating properties  

PubMed Central

The tatanans are members of a novel class of complex sesquilignan natural products recently isolated from the rhizomes of Acorus tatarinowii Schott plants. Tatanans A, B and C have previously been reported to have potent glucokinase-activating properties that exceed the in vitro activity of known synthetic antidiabetic agents. Here, using a series of sequential [3,3]-sigmatropic rearrangements, we report the total synthesis of tatanan A in 13 steps and 13% overall yield. We also complete a concise enantioselective total synthesis of more complex, atropisomeric tatanans B and C via a distinct convergent strategy based on a palladium-catalysed diastereotopic aromatic group differentiation (12 steps, 4% and 8% overall yield, respectively). A plausible biosynthetic relationship between acyclic tatanan A and spirocyclic tatanans B and C is proposed and probed experimentally. With sufficient quantities of the natural products in hand, we undertake a detailed functional characterization of the biological activities of tatanans A–C. Contrary to previous reports, our assays utilizing pure recombinant human enzyme demonstrate that tatanans do not function as allosteric activators of glucokinase. PMID:23609092

Xiao, Qing; Jackson, Jeffrey J.; Basak, Ashok; Bowler, Joseph M.; Miller, Brian G.; Zakarian, Armen

2014-01-01

429

Pyridoxine-derived bicyclic amido-, ureido-, and carbamato-pyridinols: synthesis and antiangiogenic activities.  

PubMed

We recently developed an efficient and practical synthesis for a novel series of pyridoxine-derived 6-amido-2,4,5-trimethylpyridin-3-ols and found that this novel scaffold has outstanding activity to inhibit angiogenesis measured by the quantitative chick embryo chorioallantoic membrane (CAM) assay. As an effort to extend the scope of the amidopyridinol scaffold, we here report the synthesis and antiangiogenic activities of a series of bicyclic versions of the amidopyridinol including five- and six-membered cyclic amide-, cyclic urea-, and cyclic carbamate-fused pyridinols. The six membered bicyclic derivatives were prepared by the reported procedures, and the five-membered ring-fused ones were synthesized by new synthetic methods developed in this study. CAM assays showed that both six- and five-membered lactam-fused pyridinols have activities comparable to sunitinib malate, the positive control, in inhibition of vascular endothelial growth factor-induced angiogenesis. On the other hand, the urea and the carbamate derivatives showed modest to moderate antiangiogenic activities. In summary, some bicyclic aminopyridinols can provide a good platform for structural exploitation in future medicinal chemistry work. PMID:25255328

Lee, Hyunji; Kim, Dong-Guk; Banskota, Suhrid; Lee, You Kyoung; Nam, Tae-gyu; Kim, Jung-Ae; Jeong, Byeong-Seon

2014-11-21

430

Sol–gel auto-combustion synthesis of PVP/CoFe{sub 2}O{sub 4} nanocomposite and its magnetic characterization  

SciTech Connect

Graphical abstract: - Highlights: • The Poly(vinyl pyrrolidone) (PVP) was used as a surface capping agent. • PVP/CoFe{sub 2}O{sub 4} nanocomposite was synthesized by a sol-gel auto-combustion method. • The existence of the spin-disordered surface layer was established. - Abstract: Poly(vinyl pyrrolidone)/CoFe{sub 2}O{sub 4} nanocomposite has been fabricated by a sol–gel auto-combustion method. Poly(vinyl pyrrolidone) was used as a reducing agent as well as a surface capping agent to prevent particle aggregation and stabilize the particles. The average crystallite size estimated from X-ray line profile fitting was found to be 20 ± 7 nm. The high field irreversibility and unsaturated magnetization behaviours indicate the presence of the core–shell structure in the sample. The exchange bias effect observed at 10 K suggests the existence of the magnetically aligned core surrounded by spin-disordered surface layer. The reduced remanent magnetization value of 0.6 at 10 K (higher than the theoretical value of 0.5) shows the PVP/CoFe{sub 2}O{sub 4} nanocomposite to have cubic magnetocrystalline anisotropy according to the Stoner–Wohlfarth model.

Kurtan, U. [Department of Chemistry, Fatih University, 34500 B.Çekmece, Istanbul (Turkey); Topkaya, R., E-mail: rtopkaya@gyte.edu.tr [Department of Physics, Gebze Institute of Technology, 41400 Gebze, Kocaeli (Turkey); Baykal, A. [Department of Chemistry, Fatih University, 34500 B.Çekmece, Istanbul (Turkey)

2013-11-15

431

Synthesis and characterization of nanocrystalline Nd{sup 3+}-doped gadolinium scandium aluminum garnet powders by a gel-combustion method  

SciTech Connect

Graphical abstract: The graph shows the emission spectra (?{sub ex} = 808 nm) of 1 at.% Nd:GSAG powders sintered at different temperatures for 3 h. Compared with the powder sintered at 900 °C, the PL intensity of the powder sintered at 1000 °C decreased significantly. The changes in the PL intensity should mainly due to the crystallinity and dispersion of the powders. Highlights: ? We synthesized Nd:GSAG nano-powders by gel-combustion method successfully. ? We analyzed the structure and the morphology of the heat-treated products. ? We studied the optical characteristics of Nd:GSAG nano-powders. -- Abstract: Nd{sup 3+}-doped gadolinium scandium aluminum garnet (Nd:GSAG) precursor was synthesized by a gel combustion method using metal nitrates and citric acid as raw materials. The structure and morphology of the precursor and the sintered powders were studied by means of X-ray diffraction (XRD), infrared spectroscopy (IR) and transmission electron microscopy (TEM). The results showed that the precursor transformed into pure GSAG polycrystalline phase at about 800 °C, and the powders sintered at 800–1000 °C were well-dispersed with average particle sizes in the range of 30–80 nm. Optical properties of Nd:GSAG nano-powders were characterized by using photoluminescence spectroscopy. The highest photoluminescence intensity was achieved for the powder sintered at 900 °C.

Su, Jing, E-mail: zlj007@126.com [School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044 (China)] [School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044 (China); Miao, Ju-hong; Xu, Lin-hua; Ji, Yu-qing; Wang, Chu-qin [School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044 (China)] [School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044 (China)

2012-07-15

432

Total chemical synthesis of biologically active fluorescent dye-labeled Ts1 toxin.  

PubMed

Ts1 toxin is a protein found in the venom of the Brazilian scorpion Tityus serrulatus. Ts1 binds to the domain II voltage sensor in the voltage-gated sodium channel Nav and modifies its voltage dependence. In the work reported here, we established an efficient total chemical synthesis of the Ts1 protein using modern chemical ligation methods and demonstrated that it was fully active in modifying the voltage dependence of the rat skeletal muscle voltage-gated sodium channel rNav1.4 expressed in oocytes. Total synthesis combined with click chemistry was used to label the Ts1 protein molecule with the fluorescent dyes Alexa-Fluor 488 and Bodipy. Dye-labeled Ts1 proteins retained their optical properties and bound to and modified the voltage dependence of the sodium channel Nav. Because of the highly specific binding of Ts1 toxin to Nav, successful chemical synthesis and labeling of Ts1 toxin provides an important tool for biophysical studies, histochemical studies, and opto-pharmacological studies of the Nav protein. PMID:24989851

Dang, Bobo; Kubota, Tomoya; Correa, Ana M; Bezanilla, Francisco; Kent, Stephen B H

2014-08-18

433

Synthesis and Anticancer Activity of all Known (-)-Agelastatin Alkaloids Page S1/ S35 Sunkyu Han, Dustin S. Siegel, Karen C. Morrison, Paul J. Hergenrother, and Mohammad Movassaghi  

E-print Network

Synthesis and Anticancer Activity of all Known (-)-Agelastatin Alkaloids Page S1/ S35 Sunkyu Han and Anticancer Activity of All Known (­)-Agelastatin Alkaloids Sunkyu Han, Dustin S. Siegel, Karen C. Morrison Spectra S16 #12;Synthesis and Anticancer Activity of all Known (-)-Agelastatin Alkaloids Page S2/ S35

Hergenrother, Paul J.

434

Combustion synthesis and engineering of nanoparticles for electronic, structural and superconductor applications. Annual progress report, December 1, 1992--August 19, 1993  

SciTech Connect

Fully dense, nanocrystalline ceramic articles were prepared by a new nanofabrication process. The process consists of two steps: synthesis of ceramic nanoparticles and fabrication of dense, nanocrystalline ceramic parts. The synthesis step produced 10-nanometer-diameter crystallites, and is capable of being scaled up to kilogram/hour production rates. The fabrication step produced dense parts at significantly reduced sintering temperatures and times--representing a factor of 10--100 reduction in process energy requirements. Process was demonstrated by producing ultrafine-grained yttria-stabilized ZrO{sub 2}, an important material with a variety of energy-related applications (e.g., solid electrolytes, oxygen sensors, electrode materials, thermal barrier coatings, etc.). Results from this period illustrate capabilities of this energy-efficient and directly commercializable process for producing dense, nanocrystalline, multicomponent oxide ceramics.

Stangle, G.C.; Amarakoon, V.R.W.; Schulze, W.A.

1993-08-19

435

Combustion synthesis and engineering of nanoparticles for electronic, structural and superconductor applications. Annual progress report, December 1, 1992--May 31, 1993  

SciTech Connect

Fully dense, nanocrystalline ceramic articles were prepared by the new nanofabrication process. The process consists of two steps: synthesis of ceramic nanoparticles and fabrication of dense, nanocrystalline ceramic parts. The synthesis step produced 10-nanometer-diameter crystallites, and is capable of being scaled up to kilogram/hour production rates. The fabrication step produced dense parts at significantly reduced sintering temperatures and times -- representing a factor of 10--100 reduction in process energy requirements. The process was demonstrated by producing ultrafine-grained yttria-stabilized ZrO{sub 2}, an important material with a variety of energy-related applications (solid electrolytes, oxygen sensors, electrode materials, thermal barrier coatings, etc.). Results from this period clearly illustrate the capabilities of this energy-efficient and directly commercializable process for producing dense, nanocrystalline, multicomponent oxide ceramics.

Stangle, G.C.; Amarakoon, V.R.W.; Schulze, W.A.

1993-05-28

436

Synthesis, Characterization, and Catalytic Oxygen Electroreduction Activities of Carbon-Supported PtW Nanoparticle Catalysts  

SciTech Connect

Carbon-supported PtW (PtW/C) alloy nanoparticle catalysts with well-controlled particle size, dispersion, and composition uniformity, have been synthesized by wet chemical methods of decomposition of carbonyl cluster complexes, hydrolysis of metal salts, and chemical reactions within a reverse microemulsion. The synthesized PtW/C catalysts were characterized by X-ray diffraction, high-resolution transmission electron microscopy, and energy-dispersive spectroscopy. The catalytic oxygen electroreduction activities were measured by the hydrodynamic rotating disk electrode technique in an acidic electrolyte. The influence of the synthesis method on PtW particle size, size distribution, composition uniformity, and catalytic oxygen electroreduction activity, have been investigated. Among the synthesis methods studied, PtW/C catalysts prepared by the decomposition of carbonyl cluster complexes displayed the best platinum mass activity for oxygen reduction reaction under the current small scale production; a 3.4-fold catalytic enhancement was achieved in comparison to a benchmark Pt/C standard.

Xiong, Liufeng [Honda Research Institute; More, Karren Leslie [ORNL; He, Ting [Honda Research Institute

2010-01-01

437

Synthesis and biological activities of simplified analogs of the natural PKC ligands, bryostatin-1 and aplysiatoxin.  

PubMed

Protein kinase C (PKC) isozymes play central roles in signal transduction on the cell surface and could serve as promising therapeutic targets of intractable diseases like cancer, Alzheimer's disease, and acquired immunodeficiency syndrome (AIDS). Although natural PKC ligands like phorbol esters, ingenol esters, and teleocidins have the potential to become therapeutic leads, most of them are potent tumor promoters in mouse skin. By contrast, bryostatin-1 (bryo-1) isolated from marine bryozoan is a potent PKC activator with little tumor-promoting activity. Numerous investigations have suggested bryo-1 to be a promising therapeutic candidate for the above intractable diseases. However, there is a supply problem of bryo-1 both from natural sources and by organic synthesis. Recent approaches on the synthesis of bryo-1 have focused on its simplification, without decreasing the ability to activate PKC isozymes, to develop new medicinal leads. Another approach is to use the skeleton of natural PKC ligands to develop bryo-1 surrogates. We have recently identified 10-methyl-aplog-1 (26), a simplified analog of tumor-promoting aplysiatoxin (ATX), as a possible therapeutic lead for cancer. This review summarizes recent investigations on the simplification of natural PKC ligands, bryo-1 and ATX, to develop potential medicinal leads. PMID:24677503

Irie, Kazuhiro; Yanagita, Ryo C

2014-04-01

438

Synthesis and biological activity of pyochelin, a siderophore of Pseudomonas aeruginosa.  

PubMed Central

Pyochelin, a phenolic siderophore of Pseudomonas aeruginosa, was synthesized in three steps from salicylonitrile, L-cysteine, and L-N-methylcysteine. The synthetic product was determined to be identical to natural pyochelin by 1H nuclear magnetic resonance spectroscopy, fast atom bombardment mass spectrometry, chromatographic analysis, and chemical reactivity with FeCl3 and ammoniacal silver nitrate reagent. Synthetic and natural pyochelin promoted bacterial growth in iron-depleted medium and were also found to mediate iron transport by P. aeruginosa to the same levels. Neopyochelin, a stereoisomeric by-product of the synthesis, showed less biological activity than did pyochelin in iron transport assays. PMID:3141386

Ankenbauer, R G; Toyokuni, T; Staley, A; Rinehart, K L; Cox, C D

1988-01-01

439

Phosphatidylcholine synthesis for lipid droplet expansion is mediated by localized activation of CTP:phosphocholine cytidylyltransferase.  

PubMed

Lipid droplets (LDs) are cellular storage organelles for neutral lipids that vary in size and abundance according to cellular needs. Physiological conditions that promote lipid storage rapidly and markedly increase LD volume and surface. How the need for surface phospholipids is sensed and balanced during this process is unknown. Here, we show that phosphatidylcholine (PC) acts as a surfactant to prevent LD coalescence, which otherwise yields large, lipolysis-resistant LDs and triglyceride (TG) accumulation. The need for additional PC to coat the enlarging surface during LD expansion is provided by the Kennedy pathway, which is activated by reversible targeting of the rate-limiting enzyme, CTP:phosphocholine cytidylyltransferase (CCT), to growing LD surfaces. The requirement, targeting, and activation of CCT to growing LDs were similar in cells of Drosophila and mice. Our results reveal a mechanism to maintain PC homeostasis at the expanding LD monolayer through targeted activation of a key PC synthesis enzyme. PMID:21982710

Krahmer, Natalie; Guo, Yi; Wilfling, Florian; Hilger, Maximiliane; Lingrell, Susanne; Heger, Klaus; Newman, Heather W; Schmidt-Supprian, Marc; Vance, Dennis E; Mann, Matthias; Farese, Robert V; Walther, Tobias C

2011-10-01

440

Extracts from Glycine max (soybean) induce elastin synthesis and inhibit elastase activity.  

PubMed

Elastic fibres are essential extracellular matrix components of the skin, contributing to its resilience and elasticity. In the course of skin ageing, elastin synthesis is reduced, and elastase activity is accelerated, resulting in skin sagging and reduced skin elasticity. Our studies show that non-denatured Glycine max (soybean) extracts induced elastin promoter activity, inhibited elastase activity and protected elastic fibres from degradation by exogenous elastases in vitro. Mouse and swine skins topically treated with soybean extracts showed enhanced elastic fibre network and increased desmosine content. Elastin expression was also augmented in human skin transplanted onto SCID mice in response to soy treatment. These data suggest that non-denatured soybean extracts may be used as skin care agents to reduce the signs of skin ageing. PMID:19469891

Zhao, Renbin; Bruning, Elizabeth; Rossetti, Dianne; Starcher, Barry; Seiberg, Miri; Iotsova-Stone, Violetta

2009-10-01