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Sample records for surface-induced precursor effect

  1. THE EFFECTS OF SURFACE-INDUCED LOADS ON FOREARM MUSCLE ACTIVITY DURING STEERING A BICYCLE

    Directory of Open Access Journals (Sweden)

    Pinar Arpinar-Avsar

    2013-09-01

    Full Text Available On the bicycle, the human upper extremity has two essential functions in steering the bicycle and in supporting the body. Through the handlebar, surface- induced loads are transmitted to the hand and arm of the bicycle rider under vibration exposure conditions. Thus, the purpose of the study was to investigate the effect of vibration exposure on forearm muscle activity for different road surfaces (i.e. smooth road, concrete stone pavement, rough road and for different bicycles. Ten subjects participated in experiments and two types of bicycles, i.e. Road Bike (RB and Mountain Bike (MTB are compared. The acceleration magnitudes were dominant along x and z-axes. The r.m.s acceleration values in the z direction at the stem of MTB were at most 2.56, 7.04 and 10.76 m·s-2 when pedaling respectively on asphalt road, concrete pavement and rough road. In the case of RB the corresponding values were respectively 4.43, 11.75 and 27.31 m·s-2. The cumulative normalized muscular activity levels during MTB trials on different surfaces had the same tendency as with acceleration amplitudes and have ranked in the same order from lowest to highest value. Although road bike measurements have resulted in a similar trend of increment, the values computed for rough road trials were higher than those in MTB trials. During rough road measurements on MTB, rmsEMG of extensor muscles reached a value corresponding to approximately 50% of MVC (Maximum Voluntary Contraction. During RB trials performed on rough road conditions, rmsEMG (%MVC values for the forearm flexor muscles reached 45.8% of their maximal. The level of muscular activity of forearm muscles in controlling handlebar movements has been observed to be enhanced by the increase in the level of vibration exposed on the bicycle. Since repeated forceful gripping and pushing forces to a handle of a vibratory tool can create a risk of developing circulatory, neurological, or musculoskeletal disorder, a bicycle rider

  2. Study of the thermal effect on silicon surface induced by ion beam from plasma focus device

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Z., E-mail: pscientific5@aec.org.sy [Scientific Service Department, Atomic Energy Commission of Syria, P.O. Box: 6091, Damascus (Syrian Arab Republic); Ahmad, M. [IBA Laboratory, Atomic Energy Commission of Syria, P.O. Box: 6091, Damascus (Syrian Arab Republic); Chemistry Department, Atomic Energy Commission of Syria, P.O. Box: 6091, Damascus (Syrian Arab Republic); Al-Hawat, Sh.; Akel, M. [Physics Department, Atomic Energy Commission of Syria, P.O. Box: 6091, Damascus (Syrian Arab Republic)

    2017-04-01

    Structural modifications in form of ripples and cracks are induced by nitrogen ions from plasma focus on silicon surface. The investigation of such structures reveals correlation between ripples and cracks formation in peripheral region of the melt spot. The reason of such correlation and structure formation is explained as result of thermal effect. Melting and resolidification of the center of irradiated area occur within one micro second of time. This is supported by a numerical simulation used to investigate the thermal effect induced by the plasma focus ion beams on the silicon surface. This simulation provides information about the temperature profile as well as the dynamic of the thermal propagation in depth and lateral directions. In accordance with the experimental observations, that ripples are formed in latter stage after the arrival of last ion, the simulation shows that the thermal relaxation takes place in few microseconds after the end of the ion beam arrival. Additionally, the dependency of thermal propagation and relaxation on the distance of the silicon surface from the anode is presented.

  3. Effect of Basic Residue on the Kinetics of Peptide Fragmentation Examined Using Surface-Induced Dissociation Combined with Resonant Ejection

    Energy Technology Data Exchange (ETDEWEB)

    Laskin, Julia

    2015-11-30

    In this work, resonant ejection coupled with surface-induced dissociation (SID) in a Fourier transform ion cyclotron resonance mass spectrometer is used to examine fragmentation kinetics of two singly protonated hexapeptides, RYGGFL and KYGGFL, containing the basic arginine residue and less basic lysine residue at the N-terminus. The kinetics of individual reaction channels at different collision energies are probed by applying a short ejection pulse (1 ms) in resonance with the cyclotron frequency of a selected fragment ion and varying the delay time between ion-surface collision and resonant ejection while keeping total reaction delay time constant. Rice-Ramsperger-Kassel-Marcus (RRKM) modeling of the experimental data provides accurate threshold energies and activation entropies of individual reaction channels. Substitution of arginine with less basic lysine has a pronounced effect on the observed fragmentation kinetics of several pathways, including the b2 ion formation, but has little or no effect on formation of the b5+H2O fragment ion. The combination of resonant ejection SID, time- and collision energy-resolved SID, and RRKM modeling of both types of experimental data provides a detailed mechanistic understanding of the primary dissociation pathways of complex gaseous ions.

  4. Effect of variation of precursor concentration on structural ...

    Indian Academy of Sciences (India)

    lized in industrial and domestic fields as fuel. It is referred to as town or cooking gas. This gas is ... Takeuchi 2003), solar cells (Bach et al 1998; Grätzel 2001;. Adachi 2004). Several methods for the growth of TiO2 ... response to LPG and H2 at operating temperatures of 350 and 250. ◦. C, respectively. The effect of precursor ...

  5. Magnetic reconnection and precursor effect in coaxial discharge

    International Nuclear Information System (INIS)

    Masoud, M.M.; Soliman, H.M.; El-Khalafawy, T.A.

    1988-01-01

    A precursor pulse was observed ahead of the plasma sheath produced by a coaxial electrode discharge system. The velocity of the precursor pulse was 4x10 7 cmS -1 and the velocity of the plasma sheath was 6x10 6 cmS -1 . The precursor pulse was unaffected when an axial magnetic field of 6 K.G. was applied to the propagation chamber, while the plasma sheath velocity increased and downstream structure were changed. The precursor pulse was split, sometimes, into two or more peaks, had the same shape and structure of the original one. The rest gas was heated up to 20 e.V. when the precursor pulse was destructed. The precursor pulse propagation mechanism and parameters showed that it had a solitary wave structure and behaviour. A reversed magnetic field was detected, when the plasma sheath had diamagnetic properties, where magnetic reconnection took place. Magnetic reconnection was responsible for energy transfiguration and wave generation. This was due to acceleration mechanism of charged particles occurred by the induced electric field at the moment of magnetic reconnection. The detected induced electric field had a high field intensity and fast rise time pulse. Several instabilities were referred to magnetic reconnection and the precursor pulse observed was a result of such instabilities

  6. Effect of precursors on flavonoid production by Hydrocotyle ...

    African Journals Online (AJOL)

    Callus tissue of Hydrocotyle bonariensis was initiated from the leaf of H. bonariensis treated with 2 mg/l of 2,4-dichlorophenoxyacetic acid (2,4-D) and 1 mg/l kinetin. The culture was kept at 25°C, under light (cool white fluorescent tubes, 1200 lux). To optimize the precursors to increase the production of flavonoid, different ...

  7. Theoretical model of CR Forbush-decrease and precursors effects

    Science.gov (United States)

    Lev, Dorman

    The understanding of the mechanism of CR Forbush decrease and precursor effects is important for forecasting of the great magnetic storms by using on-line one hour CR observation data. We consider in details the situation with CR distribution inside CME and how it changed with time. We suppose that shock wave before CME is semi-transpired and the coefficient of transparence depends from the CR particles rigidity. One differential equation determined the change of CR intensity inside CME by the particle energy decrease in the expanding volume and by exchange with CR particles outside the CME. The other differential equation determined the outside CR particles drift acceleration by interaction with the shock wave before CME (this effect gives increase of CR intensity before magnetic storm sudden commencement) as well as exchange with CR particles inside the CME along the IMF lines (what gives the decrease of CR intensity before the start of magnetic storm on the Earth). We calculate also the expected CR anisotropy. Obtained results we compare with observation data. It is obvious now that according to data from the past on big variations of planetary surface temperature on scales of many millions and thousands of years, the Earth’s global climate change is determined mostly by space factors, including: the moving of the Solar system around the center of our galaxy, the crossing of galactic arms and molecular dust clouds, nearby supernova and supernova remnants. Another important space factor is the cyclic variations of solar activity and the solar wind (mostly on the scale of hundreds of years and decades). The effects of space factors on the Earth’s climate are realized mostly through cosmic rays (CR) and space dust influencing the formation of clouds, thereby controlling the total energy input from the Sun into the Earth’s atmosphere. The propagation and modulation of galactic CR (generated mostly during supernova explosions and in supernova remnants in our

  8. White matter pathways mediate parental effects on children's reading precursors.

    Science.gov (United States)

    Vandermosten, Maaike; Cuynen, Lieselore; Vanderauwera, Jolijn; Wouters, Jan; Ghesquière, Pol

    2017-10-01

    Previous studies have shown that the link between parental and offspring's reading is mediated by the cognitive system of the offspring, yet information about the mediating role of the neurobiological system is missing. This family study includes cognitive and diffusion MRI (dMRI) data collected in 71 pre-readers as well as parental reading and environmental data. Using sequential path analyses, which take into account the interrelationships between the different components, we observed mediating effects of the neurobiological system. More specifically, fathers' reading skills predicted reading of the child by operating through a child's left ventral white matter pathway. For mothers no clear mediating role of the neural system was observed. Given that our study involves children who have not yet learned to read and that environmental measures were taken into account, the paternal effect on a child's white matter pathway is unlikely to be only driven by environmental factors. Future intergenerational studies focusing on the genetic, neurobiological and cognitive level of parents and offspring will provide more insight in the relative contribution of parental environment and genes. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. The precursors effects on biomimetic hydroxyapatite ceramic powders.

    Science.gov (United States)

    Yoruç, Afife Binnaz Hazar; Aydınoğlu, Aysu

    2017-06-01

    In this study, effects of the starting material on chemical, physical, and biological properties of biomimetic hydroxyapatite ceramic powders (BHA) were investigated. Characterization and chemical analysis of BHA powders were performed by using XRD, FT-IR, and ICP-AES. Microstructural features such as size and morphology of the resulting BHA powders were characterized by using BET, nano particle sizer, pycnometer, and SEM. Additionally, biological properties of the BHA ceramic powders were also investigated by using water-soluble tetrazolium salts test (WST-1). According to the chemical analysis of BHA ceramic powders, chemical structures of ceramics which are prepared under different conditions and by using different starting materials show differences. Ceramic powders which are produced at 80°C are mainly composed of hydroxyapatite, dental hydroxyapatite (contain Na and Mg elements in addition to Ca), and calcium phosphate sulfide. However, these structures are altered at high temperatures such as 900°C depending on the features of starting materials and form various calcium phosphate ceramics and/or their mixtures such as Na-Mg-hydroxyapatite, hydroxyapatite, Mg-Whitlockit, and chloroapatite. In vitro cytotoxicity studies showed that amorphous ceramics produced at 80°C and ceramics containing chloroapatite structure as main or secondary phases were found to be extremely cytotoxic. Furthermore, cell culture studies showed that highly crystalline pure hydroxyapatite structures were extremely cytotoxic due to their high crystallinity values. Consequently, the current study indicates that the selection of starting materials which can be used in the production of calcium phosphate ceramics is very important. It is possible to produce calcium phosphate ceramics which have sufficient biocompatibility at physiological pH values and by using appropriate starting materials. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. In vivo MRI evaluation of anabolic steroid precursor growth effects in a guinea pig model

    Science.gov (United States)

    Tang, Haiying; Vasselli, Joseph R.; Tong, Christopher; Heymsfield, Steven B.; Wu, Ed X.

    2015-01-01

    Anabolic steroids are widely used to increase skeletal muscle (SM) mass and improve physical performance. Some dietary supplements also include potent steroid precursors or active steroid analogs such as nandrolone. Our previous study reported the anabolic steroid effects on SM in a castrated guinea pig model with SM measured using a highly quantitative magnetic resonance imaging (MRI) protocol. The aim of the current study was to apply this animal model and in vivo MRI protocol to evaluate the growth effects of four widely used over-the-counter testosterone and nandrolone precursors: 4-androstene-3 17-dione (androstenedione), 4-androstene-3β 17β-diol (4-androsdiol), 19-nor-4-androstene-3β-17β-diol (bolandiol) and 19-nor-4-androstene-3 17-dione (19-norandrostenedione). The results showed that providing precursor to castrated male guinea pigs led to plasma steroid levels sufficient to maintain normal SM growth. The anabolic growth effects of these specific precursors on individual and total muscle volumes, sexual organs, and total adipose tissue over a 10-week treatment period, in comparison with those in the respective positive control testosterone and nandrolone groups, were documented quantitatively by MRI. PMID:19463691

  11. In vivo MRI evaluation of anabolic steroid precursor growth effects in a guinea pig model.

    Science.gov (United States)

    Tang, Haiying; Vasselli, Joseph R; Tong, Christopher; Heymsfield, Steven B; Wu, Ed X

    2009-08-01

    Anabolic steroids are widely used to increase skeletal muscle (SM) mass and improve physical performance. Some dietary supplements also include potent steroid precursors or active steroid analogs such as nandrolone. Our previous study reported the anabolic steroid effects on SM in a castrated guinea pig model with SM measured using a highly quantitative magnetic resonance imaging (MRI) protocol. The aim of the current study was to apply this animal model and in vivo MRI protocol to evaluate the growth effects of four widely used over-the-counter testosterone and nandrolone precursors: 4-androstene-3 17-dione (androstenedione), 4-androstene-3beta 17beta-diol (4-androsdiol), 19-nor-4-androstene-3beta-17beta-diol (bolandiol) and 19-nor-4-androstene-3 17-dione (19-norandrostenedione). The results showed that providing precursor to castrated male guinea pigs led to plasma steroid levels sufficient to maintain normal SM growth. The anabolic growth effects of these specific precursors on individual and total muscle volumes, sexual organs, and total adipose tissue over a 10-week treatment period, in comparison with those in the respective positive control testosterone and nandrolone groups, were documented quantitatively by MRI.

  12. The Effect of Precursor Ligands and Oxidation State in the Synthesis of Bimetallic Nano-Alloys

    KAUST Repository

    LaGrow, Alec P.

    2015-05-12

    The characteristics of bimetallic nanomaterials are dictated by their size, shape and elemental distribution. Solution synthesis is widely utilized to form nanomaterials, such as nanoparticles, with controlled size and shape. However, the effects of variables on the characteristics of bimetallic nanomaterials are not completely understood. In this study, we used a continuous-flow synthetic strategy to explore the effects of the ligands and the oxidation state of a metal precursor in a shape-controlled synthesis on the final shape of the nanomaterials and the elemental distribution within the alloy. We demonstrate that this strategy can tune the size of monodisperse PtM (M=Ni or Cu) alloy nanocrystals ranging from 3 to 16 nm with an octahedral shape using acetylacetonate or halide precursors of Pt(II), Pt(IV) and Ni or Cu (II). The nanoparticles formed from halide precursors showed an enrichment of platinum on their surfaces, and the bromides could oxidatively etch the nanoparticles during synthesis with the O2/Br- pair. The two nanocrystal precursors can be uti-lized independently and can control the size with a trend of Pt(acac)2effect of the ligand shell of a precursor during the synthesis of alloy nanoparticles as well as to control, in a scalable manner, the nanomaterial size and surface chemistry.

  13. Precursor effect on the property and catalytic behavior of Fe-TS-1 in butadiene epoxidation

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    Wu, Mei; Zhao, Huahua; Yang, Jian; Zhao, Jun; Song, Huanling; Chou, Lingjun

    2017-11-01

    The effect of iron precursor on the property and catalytic behavior of iron modified titanium silicalite molecular sieve (Fe-TS-1) catalysts in butadiene selective epoxidation has been studied. Three Fe-TS-1 catalysts were prepared, using iron nitrate, iron chloride and iron sulfate as precursors, which played an important role in adjusting the textural properties and chemical states of TS-1. Of the prepared Fe-TS-1 catalysts, those modified by iron nitrate (FN-TS-1) exhibited a significant enhanced performance in butadiene selective epoxidation compared to those derived from iron sulfate (FS-TS-1) or iron chloride (FC-TS-1) precursors. To obtain a deep understanding of their structure-performance relationship, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Temperature programmed desorption of NH3 (NH3-TPD), Diffuse reflectance UV-Vis spectra (DR UV-Vis), Fourier transformed infrared spectra (FT-IR) and thermal gravimetric analysis (TGA) were conducted to characterize Fe-TS-1 catalysts. Experimental results indicated that textural structures and acid sites of modified catalysts as well as the type of Fe species influenced by the precursors were all responsible for the activity and product distribution.

  14. Effects of infusing milk precursors into the artery on rumen fermentation in lactating cows

    Directory of Open Access Journals (Sweden)

    Xianjue Wang

    2016-06-01

    Full Text Available This experiment was conducted to investigate the effects of infusing milk precursors into the external pudic artery on rumen fermentation in lactating dairy cows. Eight multiparous Holstein cows were randomly assigned to Group A (experimental group and Group B (control group with 4 cows each. A 2 × 4 complex factor crossover design was used. Cows in Group A were fed corn straw as the only roughage, and cows in Group B were fed mixed roughage. The experiment was divided into two periods. In the first period, cows in Group A, received treatments: 1 a basal infusate as a control (CSC; 2 a milk fat precursor infusion including C16:0, C18:0, C18:1c9, C18:2c6, C18:3n3, acetic acid (CSF; 3 a milk protein precursor infusion including 16 amino acids (CSA; 4 the mixed infusion of milk fat and protein precursors (CSFA. And meanwhile, cows in Group B were infused the basal infusate as a control group. In the second period, the cows in both Groups A and B were crossed over, which cows in Group A were named as Group B and the cows originally in Group B were in Group A. The experimental results showed that cows in experimental group had higher ruminal pH compared with the control, and ruminal pH in CSC, CSF, CSA were significantly higher than those in their respective control group (P < 0.05. The concentration of ammonia nitrogen (NH3–N was significantly higher in CSA and CSFA compared with Group B (P < 0.05. We also observed that the infusion of mixed amino acids significantly increased the bacterial protein (BCP content in rumen (P < 0.05 and influenced the rumen acetic acid concentration as well as the acetic to propionic ratio (P < 0.05. Milk fat precursors infusion significantly affected butyric acid concentration (P < 0.05. In addition, the content of lipopolysaccharide (LPS in CSA was significantly higher than that in the control group (P < 0.05. It is concluded that the milk precursors infused into external pudic artery caused feedback

  15. Effect of different nickel precursors on capacitive behavior of electrodeposited NiO thin films

    Science.gov (United States)

    Kore, R. M.; Ghadge, T. S.; Ambare, R. C.; Lokhande, B. J.

    2016-04-01

    In the present study, the effect of nickel precursors containing different anions like nitrate, chloride and sulphate on the morphology and pseudocapacitance behavior of NiO is investigated. The NiO samples were prepared by using a potentiondynamic electrodeposition technique in the three electrode cell. Cyclic voltammetry technique was exploited for potentiodynamic deposition of the films. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), etc. The XRD reveals the cubic crystal structure for all samples. The SEM micrograph shows nanoflakelike, up grown nanoflakes and honeycomb like nanostructured morphologies for nitrate, chloride and sulphate precursors respectively. The capacitive behavior of these samples was recorded using cyclic voltammetry (CV), charge-discharge and electrochemical impedance spectroscopy (EIS) in 1 M KOH electrolyte. The specific capacitance values of NiO samples obtained using CV for nitrate, chloride and sulphate precursors were 136, 214 and 893 Fg-1 respectively, at the scan rate of 5 mVs-1. The charge discharge study shows high specific energy for the sample obtained from sulphate (23.98 Whkg-1) as compared to chloride (9.67 Whkg-1) and nitrate (4.9 Whkg-1), whereas samples of cholride (13.9 kWkg-1 and nitrate (10.5 kWkg-1) shows comparatively more specific power than samples obtained from sulphate (7.6 kWkg-1). The equivalent series resistance of NiO samples observed from EIS study are 1.34, 1.29 and 1.27 Ω respectively for nitrate, chloride and sulphate precursors. These results emphasizes that the samples obtained from sulphate precursors provides very low impedance through honeycomb like nanostructured morphology which supports good capacitive behavior of NiO.

  16. Effect of precursor solutions on ZnO film via solution precursor plasma spray and corresponding gas sensing performances

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Z.X., E-mail: zexin.yu@utbm.fr [Univ Bourgogne Franche Comte, CNRS, Lab ICB, UMR 6303, Site UTBM, F-90010 Belfort (France); Ma, Y.Z., E-mail: yangzhou.ma@outlook.com [School of Materials Science and Engineering, Anhui University of Technology, Ma’anshan 243002 (China); Zhao, Y.L. [Univ Bourgogne Franche Comte, CNRS, Lab ICB, UMR 6303, Site UTBM, F-90010 Belfort (France); Huang, J.B.; Wang, W.Z. [Key Lab of Safety Science of Pressurized System, Ministry of Education, School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai 200237 (China); Moliere, M.; Liao, H.L. [Univ Bourgogne Franche Comte, CNRS, Lab ICB, UMR 6303, Site UTBM, F-90010 Belfort (France)

    2017-08-01

    Highlights: • C-axis preferential oriented grown ZnO films were firstly deposited via SPPS with different solutions. • ZnO films were hydrophobic due to cauliflower and honeycomb-like surface morphologies with high surface specific area. • Gas detecting performance of (002) plane oriented ZnO was predicted and compared by “first principle calculation method”. - Abstract: Solution precursor plasma spraying (SPPS) as a novel thermal spray method was employed to deposit nano-structured ZnO thin film using different formulations of the precursor solution. This article focuses on the influence of the solution composition on the preferential orientation of crystal growth, on crystal size and surface morphology of the resulting ZnO films. The trend of preferential growth along (002) lattice plane of ZnO film was studied by slow scanning X-ray diffraction using a specific coefficient P{sub (002).} It appears that the thermal spray process promotes the buildup of ZnO films preferentially oriented along the c-axis. The shape of single particle tends to change from round shaped beads to hexagonal plates by increasing the volume ratio of ethanol in the solvent. Both cauliflower and honeycomb-like surface morphologies featuring high specific surface area and roughness were obtained through the SPPS process by varying solution composition. These ZnO films are hydrophobic with contact angle as high as 136°, which is seemingly associated with micro reliefs developing high surface specific area. Then the gas sensing performances of ZnO films preferentially oriented along (002) face were tentatively predicted using the “first principle calculation method” and were compared with those of conventional films that are mainly oriented along the (101) face. The (002) face displays better hydrogen adsorption capability than the (101) face with much larger resulting changes in electrical resistance. In conclusion, the c-axis oriented ZnO films obtained through SSPS have

  17. Effect of precursors on the solid-state synthesis of semiconducting PbS nanostructures

    Directory of Open Access Journals (Sweden)

    Sujata Kasabe

    2013-03-01

    Full Text Available In this communication, we report facile and economical in-situ preparation of lead sulphide (PbS nanorods and nanocubes within the Polyphenylene sulphide (PPS matrix. PPS plays a dual role in the synthesis of the resultant nanostructures as - (i a chalcogen source and (ii a stabilizing matrix. We studied the effect of change of lead precursor from lead nitrate to acetate on the morphological properties of the resultant nanostructures. The effect of molar ratios of the reactants (1:1, 1:5, 1:10, 1:15 and 1:20 on the morphology of the products was also studied. The resultant nanocomposites were characterized by various physico-chemical techniques like X-ray Diffractometry (XRD, SEM equipped with EDAX, TEM and UV-Visible spectroscopy. The prima-facie observations suggest effective formation and subsequent entrapment of lead sulphide nanorods and nanocubes, respectively, when lead acetate and lead nitrate precursors were used. Additionally, simultaneous occurrence of nanocrystalline cubic lead as an impurity phase is noticed in case of heated admixtures for both the precursors.

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

    Science.gov (United States)

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

    2010-01-01

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

  19. Surface-induced effects in fluctuation-based measurements of single-polymer elasticity: A direct probe of the radius of gyration

    Science.gov (United States)

    Innes-Gold, Sarah N.; Morgan, Ian L.; Saleh, Omar A.

    2018-03-01

    Single-molecule measurements of polymer elasticity are powerful, direct probes of both biomolecular structure and principles of polymer physics. Recent work has revealed low-force regimes in which biopolymer elasticity is understood through blob-based scaling models. However, the small tensions required to observe these regimes have the potential to create measurement biases, particularly due to the increased interactions of the polymer chain with tethering surfaces. Here, we examine one experimentally observed bias, in which fluctuation-based estimates of elasticity report an unexpectedly low chain compliance. We show that the effect is in good agreement with predictions based on quantifying the exclusion effect of the surface through an image-method calculation of available polymer configurations. The analysis indicates that the effect occurs at an external tension inversely proportional to the polymer's zero-tension radius of gyration. We exploit this to demonstrate a self-consistent scheme for estimating the radius of gyration of the tethered polymer. This is shown in measurements of both hyaluronic acid and poly(ethylene glycol) chains.

  20. [Effect of precursors on the production of coumarins in a suspension culture of Angelica archangelica L].

    Science.gov (United States)

    Siatka, T; Kasparová, M

    2002-01-01

    The effect of potential precursors (cinnamic acid, phenylalanine, tyrosine) in three concentrations (0.01; 0.1; 1 mmol/l) on the growth of the culture and coumarin production was investigated in the suspension culture of Angelica archangelica L. The cultures were cultivated under constant illumination (3500 lux) and in the dark. The growth of the culture in the dark was not affected by the precursors, cinnamic acid in a concentration of 1 mmol/l exerted toxic action. The growth of the culture cultivated under constant illumination was stimulated by tyrosine in a concentration of 0.1 and 1 mmol/l, and phenylalanine in a concentration of 0.1 mmol/l; phenylalanine and cinnamic acid in a concentration of 1 mmol/l inhibited the growth of the culture. In the cultivation in the dark, coumarin production was increased by phenylalanine in a concentration 0.01 mmol/l and by tyrosine in a concentration of 1 mmol/l. In the cultivation under constant illumination, coumarin production was decreased by the action of cinnamic acid, was not affected by tyrosine, and phenylalanine (0.01 and 0.1 mmol/l) increased it in comparison with the culture without precursors.

  1. The Multiple Effects of Precursors on the Properties of Polymeric Carbon Nitride

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    Wendong Zhang

    2013-01-01

    Full Text Available Polymeric graphitic carbon nitride (g-C3N4 materials were prepared by direct pyrolysis of thiourea, dicyandiamide, melamine, and urea under the same conditions, respectively. In order to investigate the effects of precursors on the intrinsic physicochemical properties of g-C3N4, a variety of characterization tools were employed to analyze the samples. The photocatalytic activity of the samples was evaluated by the removal of NO in gas phase under visible light irradiation. The results showed that the as-prepared CN-T (from thiourea, CN-D (from dicyandiamide, CN-M (from melamine, and CN-U (from urea exhibited significantly different morphologies and microstructures. The band gaps of CN-T, CN-D, CN-M, and CN-U were 2.51, 2.58, 2.56, and 2.88 eV, respectively. Both thermal stability and yield are in the following order: CN-M > CN-D > CN-T > CN-U. The photoactivity of CN-U (31.9% is higher than that of CN-T (29.6%, CN-D (22.2%, and CN-M (26.8%. Considering the cost, toxicity, and yield of the precursors and the properties of g-C3N4, the best precursor for preparation of g-C3N4 was melamine. The present work could provide new insights into the selection of suitable precursor for g-C3N4 synthesis and in-depth understanding of the microstructure-dependent photocatalytic activity of g-C3N4.

  2. MRI and image quantitation for drug assessment - growth effects of anabolic steroids and precursors.

    Science.gov (United States)

    Tang, Haiying; Wu, Ed; Vasselli, Joseph

    2005-01-01

    MRI and image quantitation play an expanding role in modern drug research, because MRI offers high resolution and non-invasive ability, and provides excellent soft tissue contrast. Moreover, with development of effective image segmentation and analysis methods, in-vivo and serial tissue growth measurements could be assessed. In the study, MR image acquisition and analysis protocol were established and validated for investigating the effects of anabolic steroids and precursors on muscle growth and body composition in a guinea pig model. Semi-automatic and interactive segmentation methods were developed to accurately label the tissue of interest for tissue volume estimation. In addition, a longitudinal tissue area outlining procedure was proposed for study of tissue geometric features in relation to tissue growth. Finally, a fully automatic data retrieval and analysis scheme was implemented to facilitate the overall huge amount of image quantitation, statistical analysis, as well as study group comparisons. As a result, highly significant differences in muscle and organ growth were detected between intact and castrated guinea pigs using the selected anabolic steroids, indicating the viability of employing such protocol to assess other anabolic steroids. Furthermore, the anabolic potential of selected steroid precursors and their effects on muscle growth, in comparison with that in respective positive control groups of castrated guinea pigs, were evaluated with the proposed protocol.

  3. Effects of different carbon precursors on synthesis of multiwall carbon nanotubes: Purification and Functionalization

    Energy Technology Data Exchange (ETDEWEB)

    Shirazi, Yaser; Tofighy, Maryam Ahmadzadeh [Research Centre for Membrane Separation Processes, Faculty of Chemical Engineering, Iran University of Science and Technology (IUST), Narmak, Tehran (Iran, Islamic Republic of); Mohammadi, Toraj, E-mail: torajmohammadi@iust.ac.ir [Research Centre for Membrane Separation Processes, Faculty of Chemical Engineering, Iran University of Science and Technology (IUST), Narmak, Tehran (Iran, Islamic Republic of); Pak, Afshin [Research Centre for Membrane Separation Processes, Faculty of Chemical Engineering, Iran University of Science and Technology (IUST), Narmak, Tehran (Iran, Islamic Republic of)

    2011-06-01

    Cyclohexanol and xylene were used as carbon precursors, for synthesis of multiwall carbon nanotubes (MWCNTs) arrays in a CVD system at temperature of 750 deg. C, using nitrogen as carrier gas and ferrocene as catalyst. Different characterization methods were employed to compare the MWCNTs structure synthesized by these two precursors. All scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA) and Raman spectroscopy results illustrated that using cyclohexanol could significantly reduce formation of amorphous carbon and catalyst particles in the as-grown CNTs. The less amorphous carbon can be attributed to in situ oxidation in presence of oxygen atom of cyclohexanol. Characterizations showed that MWCNTs with high purity could be obtained using cyclohexanol as carbon precursor. The as-grown MWCNTs were purified by oxidation and acid treatment. Characterization of the purified MWCNTs using HNO{sub 3}/H{sub 2}SO{sub 4} (1/3 or 1/1), 8 M HCl or 8 M HNO{sub 3} was carried out. The results showed that 8 M HNO{sub 3} could be considered as the best chemical to obtain more pure MWCNTs, less amorphous and metal particles and less damaged MWCNTs. The Raman spectroscopy results demonstrated that HNO{sub 3}/H{sub 2}SO{sub 4} (1/3) treatment could more disorder the MWCNTs structure and this was attributed to the bigger destroying effect of this acid treatment. Furthermore, the TEM analysis of MWCNTs before and after acid treatment revealed that acid treatment could remove encapsulated catalyst particles. The FTIR analysis illustrated that purification of the MWCNTs with nitric acid could connect the functional groups onto the outer surface of MWCNTs and this resulted in more dispersion of the MWCNTs in water.

  4. Effects of different carbon precursors on synthesis of multiwall carbon nanotubes: Purification and Functionalization

    Science.gov (United States)

    Shirazi, Yaser; Tofighy, Maryam Ahmadzadeh; Mohammadi, Toraj; Pak, Afshin

    2011-06-01

    Cyclohexanol and xylene were used as carbon precursors, for synthesis of multiwall carbon nanotubes (MWCNTs) arrays in a CVD system at temperature of 750 °C, using nitrogen as carrier gas and ferrocene as catalyst. Different characterization methods were employed to compare the MWCNTs structure synthesized by these two precursors. All scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA) and Raman spectroscopy results illustrated that using cyclohexanol could significantly reduce formation of amorphous carbon and catalyst particles in the as-grown CNTs. The less amorphous carbon can be attributed to in situ oxidation in presence of oxygen atom of cyclohexanol. Characterizations showed that MWCNTs with high purity could be obtained using cyclohexanol as carbon precursor. The as-grown MWCNTs were purified by oxidation and acid treatment. Characterization of the purified MWCNTs using HNO 3/H 2SO 4 (1/3 or 1/1), 8 M HCl or 8 M HNO 3 was carried out. The results showed that 8 M HNO 3 could be considered as the best chemical to obtain more pure MWCNTs, less amorphous and metal particles and less damaged MWCNTs. The Raman spectroscopy results demonstrated that HNO 3/H 2SO 4 (1/3) treatment could more disorder the MWCNTs structure and this was attributed to the bigger destroying effect of this acid treatment. Furthermore, the TEM analysis of MWCNTs before and after acid treatment revealed that acid treatment could remove encapsulated catalyst particles. The FTIR analysis illustrated that purification of the MWCNTs with nitric acid could connect the functional groups onto the outer surface of MWCNTs and this resulted in more dispersion of the MWCNTs in water.

  5. Effects of different carbon precursors on synthesis of multiwall carbon nanotubes: Purification and Functionalization

    International Nuclear Information System (INIS)

    Shirazi, Yaser; Tofighy, Maryam Ahmadzadeh; Mohammadi, Toraj; Pak, Afshin

    2011-01-01

    Cyclohexanol and xylene were used as carbon precursors, for synthesis of multiwall carbon nanotubes (MWCNTs) arrays in a CVD system at temperature of 750 deg. C, using nitrogen as carrier gas and ferrocene as catalyst. Different characterization methods were employed to compare the MWCNTs structure synthesized by these two precursors. All scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA) and Raman spectroscopy results illustrated that using cyclohexanol could significantly reduce formation of amorphous carbon and catalyst particles in the as-grown CNTs. The less amorphous carbon can be attributed to in situ oxidation in presence of oxygen atom of cyclohexanol. Characterizations showed that MWCNTs with high purity could be obtained using cyclohexanol as carbon precursor. The as-grown MWCNTs were purified by oxidation and acid treatment. Characterization of the purified MWCNTs using HNO 3 /H 2 SO 4 (1/3 or 1/1), 8 M HCl or 8 M HNO 3 was carried out. The results showed that 8 M HNO 3 could be considered as the best chemical to obtain more pure MWCNTs, less amorphous and metal particles and less damaged MWCNTs. The Raman spectroscopy results demonstrated that HNO 3 /H 2 SO 4 (1/3) treatment could more disorder the MWCNTs structure and this was attributed to the bigger destroying effect of this acid treatment. Furthermore, the TEM analysis of MWCNTs before and after acid treatment revealed that acid treatment could remove encapsulated catalyst particles. The FTIR analysis illustrated that purification of the MWCNTs with nitric acid could connect the functional groups onto the outer surface of MWCNTs and this resulted in more dispersion of the MWCNTs in water.

  6. Effect of diluents on soot precursor formation and temperature in ethylene laminar diffusion flames

    KAUST Repository

    Abhinavam Kailasanathan, Ranjith Kumar

    2013-03-01

    Soot precursor species concentrations and flame temperature were measured in a diluted laminar co-flow jet diffusion flame at pressures up to eight atmospheres while varying diluent type. The objective of this study was to gain a better understanding of soot production and oxidation mechanisms, which could potentially lead to a reduction in soot emissions from practical combustion devices. Gaseous samples were extracted from the centerline of an ethylene-air laminar diffusion flame, which was diluted individually with four diluents (argon, helium, nitrogen, and carbon dioxide) to manipulate flame temperature and transport properties. The diluted fuel and co-flow exit velocities (top-hat profiles) were matched at all pressures to minimize shear-layer effects, and the mass fluxes were fixed over the pressure range to maintain constant Reynolds number. The flame temperature was measured using a fine gauge R-type thermocouple at pressures up to four atmospheres. Centerline concentration profiles of major non-fuel hydrocarbons collected via extractive sampling with a quartz microprobe and quantification using GC/MS+FID are reported within. The measured hydrocarbon species concentrations are vary dramatically with pressure and diluent, with the helium and carbon dioxide diluted flames yielding the largest and smallest concentrations of soot precursors, respectively. In the case of C2H2 and C6H6, two key soot precursors, helium diluted flames had concentrations more than three times higher compared with the carbon dioxide diluted flame. The peak flame temperature vary with diluents tested, as expected, with carbon dioxide diluted flame being the coolest, with a peak temperature of 1760K at 1atm, and the helium diluted flame being the hottest, with a peak temperature of 2140K. At four atmospheres, the helium diluted flame increased to 2240K, but the CO2 flame temperature increased more, decreasing the difference to approximately 250K. © 2012 The Combustion Institute.

  7. Effect of Tumor Necrosis Factor Inhibitor Therapy on Osteoclasts Precursors in Ankylosing Spondylitis.

    Science.gov (United States)

    Perpétuo, Inês P; Raposeiro, Rita; Caetano-Lopes, Joana; Vieira-Sousa, Elsa; Campanilho-Marques, Raquel; Ponte, Cristina; Canhão, Helena; Ainola, Mari; Fonseca, João E

    2015-01-01

    Ankylosing Spondylitis (AS) is characterized by excessive local bone formation and concomitant systemic bone loss. Tumor necrosis factor (TNF) plays a central role in the inflammation of axial skeleton and enthesis of AS patients. Despite reduction of inflammation and systemic bone loss, AS patients treated with TNF inhibitors (TNFi) have ongoing local bone formation. The aim of this study was to assess the effect of TNFi in the differentiation and activity of osteoclasts (OC) in AS patients. 13 AS patients treated with TNFi were analyzed at baseline and after a minimum follow-up period of 6 months. 25 healthy donors were recruited as controls. Blood samples were collected to assess receptor activator of nuclear factor kappa-B ligand (RANKL) surface expression on circulating leukocytes and frequency and phenotype of monocyte subpopulations. Quantification of serum levels of bone turnover markers and cytokines, in vitro OC differentiation assay and qRT-PCR for OC specific genes were performed. RANKL+ circulating lymphocytes (B and T cells) and IL-17A, IL-23 and TGF-β levels were decreased after TNFi treatment. We found no differences in the frequency of the different monocyte subpopulations, however, we found decreased expression of CCR2 and increased expression of CD62L after TNFi treatment. OC number was reduced in patients at baseline when compared to controls. OC specific gene expression was reduced in circulating OC precursors after TNFi treatment. However, when cultured in OC differentiating conditions, OC precursors from AS TNFi-treated patients showed increased activity as compared to baseline. In AS patients, TNFi treatment reduces systemic pro osteoclastogenic stimuli. However, OC precursors from AS patients exposed to TNFi therapy have increased in vitro activity in response to osteoclastogenic stimuli.

  8. Effects of humoral factors on amplification of nonrecognizable erythrocytic and granulocytic precursors

    International Nuclear Information System (INIS)

    Cronkite, E.P.; Carsten, A.L.; Cohen, R.; Miller, M.E.; Moccia, G.

    1978-01-01

    The purpose of these studies was to evaluate the effects of humoral factors on amplification of nonrecognizable erythrocytic and granulocytic precursors using the in vivo plasma clot diffusion chamber and the in vitro plasma clot culture methods. Plasma erythropoietin levels changes in the reticulocyte concentration and hematocrits of irradiated and non-irradiated Long-Evans rats exposed to hypoxia were also determined. While erythropoietin plasma levels appeared to effect BFU-E and CFU-E growth, results suggest erythropoietin may not be the sole regulator of red cell production and that inhibitors or chalone-like mechanisms may be involved. Measurements made on granulocyte precursors treated with CSF containing L-cell conditioned medium revealed granulocytic colonies and burst-like formations, similar to those seen for erythrocytic growth. There is strong evidence suggesting that CSF is a regulator of granulopoiesis; however, it is not the sole regulator and it appears that inhibitors may play an in vivo role. Growth of colonies with cell numbers not a power of 2 implies either asymmetric nitosis due to loss of genetic information required for continuing division, or differences in concentration of, or ability to recognize inhibitory factors. These possibilities are examined on the basis of results using in vivo and in vitro culture techniques

  9. Effects of densification of precursor pellets on microstructures and critical current properties of YBCO melt-textured bulks

    Energy Technology Data Exchange (ETDEWEB)

    Setoyama, Yui, E-mail: setoyama@g.ecc.u-tokyo.ac.jp [Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Shimoyama, Jun-ichi; Motoki, Takanori [Department of Physics and Mathematics, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5258 (Japan); Kishio, Kohji [Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Awaji, Satoshi [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577 (Japan); Kon, Koichi; Ichikawa, Naoki; Inamori, Satoshi; Naito, Kyogo [TEP corporation, 2-20-4 Kosuge, Katsushika-ku, Tokyo 124-0001 (Japan)

    2016-12-15

    Highlights: • YBCO bulk superconductors were fabricated from densified precursor disks. • Densification of precursor disks led to the decrease in residual voids for bulks. • YBCO melt-textured bulks with low porosity exhibited high J{sub c} in magnetic fields. • Vortex states in YBCO bulks can be possibly affected by their porosity. - Abstract: Effects of densification of precursor disks on the density of residual voids and critical current properties for YBCO melt-textured bulk superconductors were systematically investigated. Six YBCO bulks were prepared from precursor pellets with different initial particle sizes of YBa{sub 2}Cu{sub 3}O{sub y} (Y123) powder and applied pressures for pelletization. It was revealed that use of finer Y123 powder and consolidation using cold-isostatic-pressing (CIP) with higher pressures result in reduction of residual voids at inner regions of bulks and enhance J{sub c} especially under low fields below the second peak.

  10. Effect of Tumor Necrosis Factor Inhibitor Therapy on Osteoclasts Precursors in Rheumatoid Arthritis

    Directory of Open Access Journals (Sweden)

    Inês P. Perpétuo

    2017-01-01

    Full Text Available Objective. Tumor necrosis factor (TNF increases circulating osteoclast (OC precursors numbers by promoting their proliferation and differentiation. The aim of this study was to assess the effect of TNF inhibitors (TNFi on the differentiation and activity of OC in rheumatoid arthritis (RA patients. Methods. Seventeen RA patients treated with TNFi were analyzed at baseline and after a minimum follow-up period of 6 months. Blood samples were collected to assess receptor activator of nuclear factor kappa-B ligand (RANKL surface expression on circulating leukocytes and frequency and phenotype of monocyte subpopulations. Quantification of serum levels of bone turnover markers, in vitro OC differentiation assays, and qRT-PCR for OC specific genes was performed. Results. After TNFi therapy, patients had reduced RANKL surface expression in B-lymphocytes and the frequency of circulating classical CD14brightCD16− monocytes was decreased. Serum levels of sRANKL, sRANKL/OPG ratio, and CTX-I were reduced in RA patients after TNFi treatment. Moreover, after exposure to TNFi, osteoclast differentiation and activity were decreased, as well as the expression of TRAF6 and cathepsin K. Conclusion. We propose that TNFi arrests bone loss and erosion, through two pathways: direct reduction of osteoclast precursor numbers and inhibition of intracellular signaling pathways acting through TRAF6.

  11. Effect of different precursors in the chemical synthesis of ZnO nanocrystals

    International Nuclear Information System (INIS)

    Gusatti, M.; Barroso, G.S.; Souza, D.A.R.; Rosario, J.A.; Lima, R.B.; Silva, L.A.; Riella, H.G.; Kuhnen, N.C.; Campos, C.E.M.

    2010-01-01

    This work aims to evaluate the effect of ZnCl 2 and Zn(NO 3 ) 2 .6H 2 O precursors in the synthesis of ZnO nanocrystals. The materials were obtained at a temperature of 90 deg C by a simple solochemical route. The resulting samples were characterized with respect to the determination of the formed phases, particle size and morphology, using the techniques of X-ray diffraction (XRD) and transmission electron microscopy (TEM). These characterization techniques confirmed that the sample obtained with Zn(NO 3 ) 2. 6H 2 O has hexagonal crystal structure of ZnO and dimensions in the nanoscale. However, the material formed with ZnCl 2 was composed of a mixture of the ZnO phase and another correspondent to the Zn 5 (OH) 8 Cl 2 .H 2 O phase. For both precursors, the predominant morphology of the obtained ZnO nanocrystals is rod- like structure.(author)

  12. Effect of different precursors in the chemical synthesis of ZnO nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Gusatti, M.; Barroso, G.S.; Souza, D.A.R.; Rosario, J.A.; Lima, R.B.; Silva, L.A.; Riella, H.G.; Kuhnen, N.C. [Universidade Federal de Santa Catarina (DEQA/UFSC), Florianopolis, SC (Brazil). Dept. de Engenharia Quimica e de Alimentos; Campos, C.E.M. [Universidade Federal de Santa Catarina (DF/UFSC), Florianopolis, SC (Brazil). Dept. de Fisica

    2010-07-01

    This work aims to evaluate the effect of ZnCl{sub 2} and Zn(NO{sub 3}){sub 2}.6H{sub 2}O precursors in the synthesis of ZnO nanocrystals. The materials were obtained at a temperature of 90 deg C by a simple solochemical route. The resulting samples were characterized with respect to the determination of the formed phases, particle size and morphology, using the techniques of X-ray diffraction (XRD) and transmission electron microscopy (TEM). These characterization techniques confirmed that the sample obtained with Zn(NO{sub 3}){sub 2.}6H{sub 2}O has hexagonal crystal structure of ZnO and dimensions in the nanoscale. However, the material formed with ZnCl{sub 2} was composed of a mixture of the ZnO phase and another correspondent to the Zn{sub 5}(OH){sub 8}Cl{sub 2}.H{sub 2}O phase. For both precursors, the predominant morphology of the obtained ZnO nanocrystals is rod- like structure.(author)

  13. Solution-processed organic field-effect transistors based on dinaphthothienothiophene precursor with chemically modified electrodes

    Science.gov (United States)

    Nagase, Takashi; Abe, Souichiro; Kobayashi, Takashi; Kimura, Yu; Hamaguchi, Azusa; Ikeda, Yoshinori; Naito, Hiroyoshi

    2017-11-01

    Bottom-gate organic field-effect transistors (OFETs) based on a soluble precursor of dinaphtho[2,3-b:2’,3’-f]thieno[3,2-b]thiophene (DNTT) with bottom-contact source-drain electrodes chemically modified with pentafluorobenzenethiol (PFBT) have been fabricated. The preparation of DNTT films using CYTOP overcoat layers allows the solution processing of bottom-gate/bottom-contact DNTT FETs with good electrical contacts between the PFBT-treated Au electrodes and the DNTT molecules. The DNTT FETs processed using CYTOP overcoat layers exhibit the field-effect mobilities of up to 0.37 cm2 V‑1 s‑1. High maximum mobility of 0.29 cm2 V‑1 s‑1 has been achieved in solution-processed DNTT FETs with channel length of 5 μm.

  14. Numerical Investigation on the Effects of a Precursor Wetting Film on the Displacement of Two Immiscible Phases Along a Channel

    KAUST Repository

    Bao, Kai

    2015-10-08

    A set of numerical experiments has been conducted to study the effect of a precursor fluid layer on the motion of two phase system in a channel. This system is characterized by coupled Cahn-Hillard and Navier-Stokes system together with slip boundary conditions. The solution of the governing equation involves first the solution of Cahn-Hillard equation with semi-implicit and Mixed finite element discritization with a convex splitting scheme. The Navier-Stokes equations are then solved with a P2-P0 mixed finite element method. Three cases have been investigated; in the first the effect of different wettability scenarios with no precursor layer has been investigated. In the second scenario, the effect of the precursor layer for different wettability conditions is investigated. In the third case, the effect of the thickness of the precursor layer is investigated. It is found that, wettability conditions have considerable effect on the flow of the considered two-phase system. Furthermore the existence of the precursor layer has additional influence on the breakthrough of the phases.

  15. Effect of Precursor Concentration on Structural Optical and Electrical Properties of NiO Thin Films Prepared by Spray Pyrolysis

    Directory of Open Access Journals (Sweden)

    Rafia Barir

    2017-01-01

    Full Text Available Undoped nickel oxide (NiO thin films were deposited on 500°C heated glass substrates using spray pyrolysis method at (0.015–0.1 M range of precursor. The latter was obtained by decomposition of nickel nitrate hexahydrate in double distilled water. Effect of precursor concentration on structural, optical, and electrical properties of NiO thin films was investigated. X-ray diffraction (XRD shows the formation of NiO under cubic structure with single diffraction peak along (111 plane at 2θ=37.24°. When precursor concentration reaches 0.1 M, an increment in NiO crystallite size over 37.04 nm was obtained indicating the product nano structure. SEM images reveal that beyond 0.04 M as precursor concentration the substrate becomes completely covered with NiO and thin films exhibit formation of nano agglomerations at the top of the sample surface. Ni-O bonds vibrations modes in the product of films were confirmed by FT-IR analysis. Transparency of the films ranged from 57 to 88% and band gap energy of the films decreases from 3.68 to 3.60 eV with increasing precursor concentration. Electrical properties of the elaborated NiO thin films were correlated to the precursor concentration.

  16. The effect of precursor aging on optical and electrochromic properties of WO3 thin films for making smart windows

    Directory of Open Access Journals (Sweden)

    A Abareshi

    2015-01-01

    Full Text Available This paper proposes a suitable method for increasing effective surface area of electrodeposited WO3 thin films. This is done because effective surface area improves optical and electrochromic properties in smart windows. Therefore, we investigated precursor aging atperoxytungstate precursor (0, 24, 48 and 72 h. Experiments showed by increasing aging time of the precursor solution, larger aggregates were formed. Their morphology, optical and cyclic voltammogram characterization showed that increasing aging time improves optical and electrochromic properties of WO3 thin films in 1M LiClO4-PC electrolyte. The WO3 films with aging time of 72 h exhibited a noticeable EC performance with variation of transmittance up to 72% at 633nm. The result indicated that using two electrochromic materials with complementary properties could improve the function of the device

  17. The effect of precursor on the optical properties of carbon quantum dots synthesized by hydrothermal/solvothermal method

    Science.gov (United States)

    Mozdbar, Afsaneh; Nouralishahi, Amideddin; Fatemi, Shohreh; Mirakhori, Ghazaleh

    2018-01-01

    In the recent decade, Carbon Quantum Dots (CQDs) have attracted lots of attention due to their excellent properties such as tunable photoluminescence, high chemical stability, low toxicity, and biocompatibility. Among all synthesis methods, the hydrothermal/solvothermal rout has been considered as one of the most common and simplest method. The type of precursors can affect the size of CQDs and determine their surface functional groups, the essential properties that deeply influence the optical specifications. In this work, the effect of different precursors on the final properties of carbon quantum dots is investigated. The carbon quantum dots were synthesized by hydrothermal/solvothermal rout using citric acid, thiourea, ethylamine and monoethanolamine as precursors in almost the same conditions of time and temperature. Resultant CQDs were characterized by using FTIR, UV-Visible Spectroscopy and Photoluminescence (PL) analysis. The results of UV-Vis spectroscopy showed that quantum dots synthesized from monoethanolamine have wider absorption band rather than the CQDs from other precursors and the absorption edge shifted from about 270 nm for ethylamine to about 470 nm in monoethanolamine. Furthermore, the results demonstrate that using citric acid and monoethanolamine as precursor improved production efficiency and emission quantum yield of the carbon dots.

  18. Thermal aging effect of vanadyl acetylacetonate precursor for deposition of VO{sub 2} thin films with thermochromic properties

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Jung-Hoon [Department of Chemistry, Sungkyunkwan University, 440-746 Suwon (Korea, Republic of); Nam, Sang-Hun [Institute of Basic Science, Sungkyunkwan University, 440-746 Suwon (Korea, Republic of); Kim, Donguk; Kim, Minha [School of Electronic and Electrical Engineering, Sungkyunkwan University (Korea, Republic of); Seo, Hyeon Jin; Ro, Yu Hyeon [Department of Chemistry, Sungkyunkwan University, 440-746 Suwon (Korea, Republic of); Joo, Yong Tae [YOUNG DO Glass Industry Co., Ltd., Jeongeup (Korea, Republic of); Lee, Jaehyeong [School of Electronic and Electrical Engineering, Sungkyunkwan University (Korea, Republic of); Boo, Jin-Hyo, E-mail: jhboo@skku.edu [Department of Chemistry, Sungkyunkwan University, 440-746 Suwon (Korea, Republic of); Institute of Basic Science, Sungkyunkwan University, 440-746 Suwon (Korea, Republic of)

    2016-10-15

    Highlights: • 7 day aged VO(acac){sub 2} sol shows enhanced adhesivity on the SiO{sub 2} compared with non-aged sol. • The aging process has significantly affected the morphologies of VO{sub 2} films. • From the FT-IR spectra, thermal aging process provides the deformation of precursor. • The metal insulator transition (MIT) efficiency (ΔT{sub at2000} {sub nm}) reached a maximum value of 51% at 7 day aging. • Thermal aging process could shorten the aging time of sol solution. - Abstract: Thermochromic properties of vanadium dioxide (VO{sub 2}) have been studied extensively due to their IR reflection applications in energy smart windows. In this paper, we studied the optical switching property of VO{sub 2} thin film, depending on the thermal aging time of the vanadyl acetylacetonate (VO(acac){sub 2}) precursor. We found the alteration of the IR spectra of the precursor by tuning the aging time as well as heat treatments of the precursor. An aging effect of vanadium precursor directly affects the morphologies, optical switching property and crystallinity of VO{sub 2} films. The optimum condition was achieved at the 7 day aging time with metal insulator transition (MIT) efficiency of 50%.

  19. Effects of densification of precursor pellets on microstructures and critical current properties of YBCO melt-textured bulks

    Science.gov (United States)

    Setoyama, Yui; Shimoyama, Jun-ichi; Motoki, Takanori; Kishio, Kohji; Awaji, Satoshi; Kon, Koichi; Ichikawa, Naoki; Inamori, Satoshi; Naito, Kyogo

    2016-12-01

    Effects of densification of precursor disks on the density of residual voids and critical current properties for YBCO melt-textured bulk superconductors were systematically investigated. Six YBCO bulks were prepared from precursor pellets with different initial particle sizes of YBa2Cu3Oy (Y123) powder and applied pressures for pelletization. It was revealed that use of finer Y123 powder and consolidation using cold-isostatic-pressing (CIP) with higher pressures result in reduction of residual voids at inner regions of bulks and enhance Jc especially under low fields below the second peak.

  20. Ultrasound, its effects on ADU precipitation as precursor of uranium oxides; Ultrasonido, sus efectos en la precipitacion de ADU como precursor de oxidos de uranio

    Energy Technology Data Exchange (ETDEWEB)

    Mendez de Leo, Lucila; Sassone, Ariel; Novara, Oscar; Boero, Norma [Comision Nacional de Energia Atomica, Buenos Aires (Argentina). Planta de Fabricacion de Polvos de Uranio

    1999-11-01

    Ammonium poliuranate (ADU) is used as precursor of uranium oxides which are used as fuel for research reactors. The morphology of the oxides depends strongly on the structure of ADU. In this work we study the effect of acoustic energy of high frequency (ultrasound), on ADU precipitation for the obtention of U{sub 3} O{sub 8} and U O{sub 2}. Ultrasound changes ADU`s crystalline structure allowing the performance of a controlled precipitation. Experiences have been performed varying the times of ULTRASOUND appliance. X - Ray studies sustained the crystalline structure change. The difference in the state of agglomeration of particles was observed by electron scanning microscopy. This characteristic is maintained throughout the different thermal treatment performed on the powders (calcination at 800 deg C for U{sub 3} O{sub 8}, and 700 deg C in N{sub 2} - H{sub 2} atmosphere for U O{sub 2}). The oxides were characterized measuring specific area and particle size distribution. The results were good, being the change in the agglomeration state and ADU`s formula the most important features. (author) 5 refs., 4 figs., 2 tabs.

  1. Effects of simulated altitude (normobaric hypoxia on cardiorespiratory parameters and circulating endothelial precursors in healthy subjects

    Directory of Open Access Journals (Sweden)

    Pierini Alberto

    2007-08-01

    Full Text Available Abstract Background Circulating Endothelial Precursors (PB-EPCs are involved in the maintenance of the endothelial compartment being promptly mobilized after injuries of the vascular endothelium, but the effects of a brief normobaric hypoxia on PB-EPCs in healthy subjects are scarcely studied. Methods Clinical and molecular parameters were investigated in healthy subjects (n = 8 in basal conditions (T0 and after 1 h of normobaric hypoxia (T1, with Inspiratory Fraction of Oxygen set at 11.2% simulating 4850 mt of altitude. Blood samples were obtained at T0 and T1, as well as 7 days after hypoxia (T2. Results In all studied subjects we observed a prompt and significant increase in PB-EPCs, with a return to basal value at T2. The induction of hypoxia was confirmed by Alveolar Oxygen Partial Pressure (PAO2 and Spot Oxygen Saturation decreases. Heart rate increased, but arterial pressure and respiratory response were unaffected. The change in PB-EPCs percent from T0 to T1 was inversely related to PAO2 at T1. Rapid (T1 increases in serum levels of hepatocyte growth factor and erythropoietin, as well as in cellular PB-EPCs-expression of Hypoxia Inducible Factor-1α were observed. Conclusion In conclusion, the endothelial compartment seems quite responsive to standardized brief hypoxia, possibly important for PB-EPCs activation and recruitment.

  2. Effects of Escherichia coli on mixotrophic growth of Chlorella minutissima and production of biofuel precursors.

    Directory of Open Access Journals (Sweden)

    Brendan T Higgins

    Full Text Available Chlorella minutissima was co-cultured with Escherichia coli in airlift reactors under mixotrophic conditions (glucose, glycerol, and acetate substrates to determine possible effects of bacterial contamination on algal biofuel production. It was hypothesized that E. coli would compete with C. minutissima for nutrients, displacing algal biomass. However, C. minutissima grew more rapidly and to higher densities in the presence of E. coli, suggesting a symbiotic relationship between the organisms. At an initial 1% substrate concentration, the co-culture produced 200-587% more algal biomass than the axenic C. minutissima cultures. Co-cultures grown on 1% substrate consumed 23-737% more of the available carbon substrate than the sum of substrate consumed by E. coli and C. minutissima alone. At 1% substrate, total lipid and starch productivity were elevated in co-cultures compared to axenic cultures indicating that bacterial contamination was not detrimental to the production of biofuel precursors in this specific case. Bio-fouling of the reactors observed in co-cultures and acid formation in all mixotrophic cultures, however, could present challenges for scale-up.

  3. The Effects of Acute Dopamine Precursor Depletion on the Reinforcing Value of Exercise in Anorexia Nervosa.

    Directory of Open Access Journals (Sweden)

    Caitlin B O'Hara

    Full Text Available This study investigated whether dopaminergic systems are involved in the motivation to engage in behaviours associated with anorexia nervosa (AN, specifically, the drive to exercise. Women recovered from AN (AN REC, n = 17 and healthy controls (HC, n = 15 were recruited. The acute phenylalanine/tyrosine depletion (APTD method was used to transiently decrease dopamine synthesis and transmission. The effect of dopamine precursor depletion on drive to exercise was measured using a progressive ratio (PR exercise breakpoint task. Both groups worked for the opportunity to exercise, and, at baseline, PR breakpoint scores were higher in AN REC than HC. Compared to values on the experimental control session, APTD did not decrease PR breakpoint scores in AN REC, but significantly decreased scores in HC. These data show that women recovered from AN are more motivated to exercise than HC, although in both groups, activity is more reinforcing than inactivity. Importantly, decreasing dopamine does not reduce the motivation to exercise in people recovered from AN, but in contrast, does so in HC. It is proposed that in AN, drive to exercise develops into a behaviour that is largely independent of dopamine mediated reward processes and becomes dependent on cortico-striatal neurocircuitry that regulates automated, habit- or compulsive-like behaviours. These data strengthen the case for the involvement of reward, learning, habit, and dopaminergic systems in the aetiology of AN.

  4. Biochemical precursor effects on the fatty acid production in cell suspension cultures of Theobroma cacao L.

    Science.gov (United States)

    Parra, O; Gallego, A M; Urrea, A; Rojas, L F; Correa, C; Atehortúa, L

    2017-02-01

    Cocoa butter (CB) is composed of 96% palmitic, stearic, oleic, linoleic and linolenic fatty acids that are responsible for the hardness, texture and fusion properties of chocolate. Through in vitro plant cell culture it is possible to modify CB lipid profiles and to study the fatty acid biosynthesis pathway on a subcellular level, evaluating fundamental aspects to enhance in vitro fatty acid production in a specific and controlled way. In this research, culture media was supplemented with acetate, biotin, pyruvate, bicarbonate and glycerol at three different concentrations and the effects on the biomass production (g/L), cell viability, and fatty acids profile and production was evaluated in in vitro cell suspensions culture. It was found that biotin stimulated fatty acid synthesis without altering cell viability and cell growth. It was also evident a change in the lipid profile of cell suspensions, increasing middle and long chain fatty acids proportion, which are unusual to those reported in seeds; thus implying that it is possible to modify lipid profiles according to the treatment used. According to the results of sucrose gradients and enzyme assays performed, it is proposed that cacao cells probably use the pentose phosphate pathway, mitochondria being the key organelle in the carbon flux for the synthesis of reductant power and fatty acid precursors. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  5. Reproducibility of aluminum foam properties: Effect of precursor distribution on the structural anisotropy and the collapse stress and its dispersion

    International Nuclear Information System (INIS)

    Nosko, M.; Simancik, F.; Florek, R.

    2010-01-01

    The porous structure of aluminum foam manufactured through the foaming of precursors containing blowing agent is stochastic in nature, usually with a random distribution of pores of different size and shape, creating difficulties in the modeling and prediction of foam properties. In this study, the effect of the initial location of the precursor material in the mold on the foam structure and compression behavior was investigated. Structural characterization showed that the porosity distribution, surface skin thickness and pore orientation was affected by the location of the precursors in the mold and by the extrusion direction of the precursors. Moreover, compression tests demonstrated a significant effect of the structural anisotropy on the collapse stress and its dispersion. The collapse stress of the foam increased if the loading was performed parallel to the thicker surface skin or parallel to the preferential pore orientation, leading to a 20% difference in collapse stress. The dispersion of the collapse stress could be significantly decreased if the loading was performed with regard to the structural anisotropy.

  6. Effects of Ionizing Radiation and Glutathione Precursor on Antioxidant Enzyme and Cell Survival in Yeast

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jinkyu; Roh, Changhyun; Ryu, Taeho; Park, Jiyoung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Nili, Michael A. [Oxiage Cosmeceutical Research Institute, Virginia (United States)

    2013-05-15

    Cells react to such an induced oxidative stress through scavenging the generated reactive oxygen species to reduce oxidative damage. Antioxidant enzymes such as glutathione peroxidase, catalase, and superoxide dismutase are immediately triggered for reactive oxygen species. N-acetyl-L-cysteine (NAC), a precursor of glutathione, is one of the antioxidants. The effect of NAC as an antioxidant and/or a cell rescue agent was investigated in the present study. Glutathione (GSH) is the most abundant intracellular thiol, which involves in antioxidant defense via direct interaction with ROS or via activities of detoxication enzymes like glutathione peroxidases (GPx). NAC flowed in the cell is converted to cysteine by deacetylation, that is supplied to the depleted GSH by oxidative stress. NAC prevents the depletion of GSH by radiation, increases the production of GSH, and improves enzymes activity such as GPx and alkaline phosphatase. Cell growth and survivorship and transcriptional level of glutathione gene are analyzed in two yeast strains exposed to combined treatment of NAC with gamma-rays. The effect of NAC on cell growth was measured during 72 hours. The cell growth was hampered by higher concentrations of NAC at stationary phase. NAC, however, didn't affect the cell division at the exponential phase. The survival of the cells decreased with radiation dose. The cell viability of the strain W303-1A was reduced significantly at the low dose (10 and 30 Gy). By comparison, the strain W303-1A was more sensitive to radiation with having a half lethal dose (LD{sub 50}) of about 20 Gy. The quantitative RT-PCR analysis showed that the transcriptional expression of antioxidant enzyme gene GPX1 increased after irradiation while the expression of the gene decreased by the combined treatment of NAC with 100 Gy radiation. The present study shows that NAC can directly scavenge ROS against oxidative stress in vivo. In conclusion, NAC can prevent radiation-induced oxidative

  7. Effects of Ionizing Radiation and Glutathione Precursor on Antioxidant Enzyme and Cell Survival in Yeast

    International Nuclear Information System (INIS)

    Kim, Jinkyu; Roh, Changhyun; Ryu, Taeho; Park, Jiyoung; Nili, Michael A.

    2013-01-01

    Cells react to such an induced oxidative stress through scavenging the generated reactive oxygen species to reduce oxidative damage. Antioxidant enzymes such as glutathione peroxidase, catalase, and superoxide dismutase are immediately triggered for reactive oxygen species. N-acetyl-L-cysteine (NAC), a precursor of glutathione, is one of the antioxidants. The effect of NAC as an antioxidant and/or a cell rescue agent was investigated in the present study. Glutathione (GSH) is the most abundant intracellular thiol, which involves in antioxidant defense via direct interaction with ROS or via activities of detoxication enzymes like glutathione peroxidases (GPx). NAC flowed in the cell is converted to cysteine by deacetylation, that is supplied to the depleted GSH by oxidative stress. NAC prevents the depletion of GSH by radiation, increases the production of GSH, and improves enzymes activity such as GPx and alkaline phosphatase. Cell growth and survivorship and transcriptional level of glutathione gene are analyzed in two yeast strains exposed to combined treatment of NAC with gamma-rays. The effect of NAC on cell growth was measured during 72 hours. The cell growth was hampered by higher concentrations of NAC at stationary phase. NAC, however, didn't affect the cell division at the exponential phase. The survival of the cells decreased with radiation dose. The cell viability of the strain W303-1A was reduced significantly at the low dose (10 and 30 Gy). By comparison, the strain W303-1A was more sensitive to radiation with having a half lethal dose (LD 50 ) of about 20 Gy. The quantitative RT-PCR analysis showed that the transcriptional expression of antioxidant enzyme gene GPX1 increased after irradiation while the expression of the gene decreased by the combined treatment of NAC with 100 Gy radiation. The present study shows that NAC can directly scavenge ROS against oxidative stress in vivo. In conclusion, NAC can prevent radiation-induced oxidative stress by

  8. Effect of Chlorine precursor in surface and cataytic properties of Fe/TiO2 Catalysts

    OpenAIRE

    López, Tessi; Pecchi, Gina; Moreno, Abel; García Fierro, José Luis; Gómez, R.; Reyes, P.

    2002-01-01

    Titania-supported iron (1wt%) catalysts were prepared by the sol-gel method using different gelation pH (3 and 9), metal precursors (FeCl2 and FeCl3) and calcination temperatures (873 and 1073K). Characterization data of calcined catalysts revealed that in all samples the dominant iron species is Fe3+ and the crystalline phase of the TiO2 substrate depends on the gelation pH and the metal precursor used. It was found that in the Fe/TiO2 ex-FeCl3 samples an important part of the iron ions beca...

  9. Effects of Bark Beetle Infestation on Secondary Organic Aerosol Precursors in the Western United States

    Science.gov (United States)

    Huff Hartz, K. E.; Amin, H.; Dodson, C.; Atkins, P. T.; Hallar, G.

    2009-12-01

    Bark beetles are a potentially destructive force in forest ecosytems; however, it is not known how insect attacks affect the atmosphere. Other insects, such as the weevil (Strophosoma melanogrammum) attacks on spruce trees in Denmark, have a significant local effect on monoterpene emissions. In fact, a single weevil induced a three-fold increase in monoterpene emission, and the response lasted for several weeks. Mountain pine bark beetles (Dendroctonus ponderosae) have infested the forests in the vicinity of Storm Peak Laboratory near Steamboat Springs, Colorado. Emissions were sampled from the headspace of bark at the trunk and from the tree branches in the canopy from bark beetle infested and healthy lodgepole pine (Pinus contorta var. latifolia) and Engelmann spruce (Picea engelmannii) trees. The emissions were collected onto scent traps, containing 110 mg of Porapak Q sorbent, using PAS-500 micro air samplers set to a 0.4 mL/min flow rate for two hours. After collection, the scent traps were spiked with a recovery standard, perdeutrated decane, and extracted with 1.5 mL hexanes (in three portions). The analytes in the extracts were separated and detected using gas chromatography/mass spectroscopy. The analytes were identified and quantified using calibration curves from authentic standards, and when authentic standards were not available, the NIST mass spectra library and Adams retention time indices were used. The samples from lodgepole pine trees suggest an enhancement in the 3-carene, beta-phellandrene, and estragole (methyl chavicol) emissions upon bark beetle infestation. The samples from the Engelmann spruce trees suggest an enhancement in the 1,4-cineole, p-cymene, and beta-phellandrene emissions upon bark beetle infestation. A shift in the type and the quantity of VOC emissions due to bark beetle infestation may lead increases in SOA from these forests, since potent SOA precursors are produced.

  10. Effect of precursor mass on product phase composition in plasma dynamic synthesis of tungsten carbide

    Science.gov (United States)

    Shatrova, K. N.; Sivkov, A. A.; Shanenkov, I. I.; Saigash, A. S.

    2017-05-01

    An interest in WC1-x cubic tungsten carbide results from its catalytic properties similar to those of platinum group metals and the synergistic effect between WC1-x and Pt in reactions of hydrogen evolution and hydrogen oxidation. However, according to the phase diagram of the W-C system, the cubic phase WC1-x only exists in a narrow range of temperature stability (about 2798-3058 K), which makes it difficult for being obtained. To date, there are different methods for synthesizing tungsten carbide powder with a low content of cubic phase that complicates the study of WC1-x properties. A direct plasma dynamic synthesis is known as one of the promising methods to produce WC1-x. The aim of this work is to find the optimal amount of tungsten precursor to obtain cubic tungsten carbide with a high purity by plasma dynamic method. The synthesized products were examined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The XRD patterns showed that the main phase was cubic tungsten carbide with negligible content of hexagonal tungsten carbide W2C and pure tungsten W. According to a quantitative analysis of synthesized products, which were obtained using masses of initial tungsten equal to 1.0, 0.7, 0.6 and 0.5 gram, the yield of WC1-x phase was 84, 89, 95 and 92 wt%, respectively. The results of TEM displayed that the synthesized powders consist of crystallites, having the size less than 100 nm (WC1-x), and a carbon matrix. This carbon was not detected in XRD due to its presence as an amorphous phase.

  11. Effect of precursor concentration, temperature and capping group on the morphology of CdS nanoparticles

    CSIR Research Space (South Africa)

    Moloto, N

    2008-01-01

    Full Text Available A novel ligand to the synthesis of nanoparticles has been employed in this study. A Tetramethylthiuram disulphide cadmium complex (abundant in sulphur atoms) was used as a single-source precursor for the synthesis of CdS nanoparticles. The Cd...

  12. Dutch children at family risk of dyslexia: precursors, reading development, and parental effects

    NARCIS (Netherlands)

    van Bergen, E.; de Jong, P.F.; Regtvoort, A.; Oort, F.; van Otterloo, S.; van der Leij, A.

    2011-01-01

    The study concerns reading development and its precursors in a transparent orthography. Dutch children differing in family risk for dyslexia were followed from kindergarten through fifth grade. In fifth grade, at-risk dyslexic (n = 22), at-risk non-dyslexic (n = 45), and control children (n = 12)

  13. Dutch children at family risk of dyslexia : Precursors, reading development, and parental effects

    NARCIS (Netherlands)

    Van Bergen, Elsje; De Jong, Peter F.; Regtvoort, Anne; Oort, Frans; Van Otterloo, Sandra; van der Leij, Aryan

    The study concerns reading development and its precursors in a transparent orthography. Dutch children differing in family risk for dyslexia were followed from kindergarten through fifth grade. In fifth grade, at-risk dyslexic (n = 22), at-risk non-dyslexic (n = 45), and control children (n = 12)

  14. Effect of temperature, precursor concentration and capping group on the shape of Cds nanoparticles

    CSIR Research Space (South Africa)

    Moloto, N

    2009-01-01

    Full Text Available A novel ligand to the synthesis of nanoparticles has been employed in this study. A Tetramethylthiuram disulphide cadmium complex (abundant in sulphur atoms) was used as a single-source precursor for the synthesis of CdS nanoparticles. The Cd...

  15. Dutch Children at Family Risk of Dyslexia: Precursors, Reading Development, and Parental Effects

    Science.gov (United States)

    van Bergen, Elsje; de Jong, Peter F.; Regtvoort, Anne; Oort, Frans; van Otterloo, Sandra; van der Leij, Aryan

    2011-01-01

    The study concerns reading development and its precursors in a transparent orthography. Dutch children differing in family risk for dyslexia were followed from kindergarten through fifth grade. In fifth grade, at-risk dyslexic (n = 22), at-risk non-dyslexic (n = 45), and control children (n = 12) were distinguished. In kindergarten, the at-risk…

  16. Effect of precursor concentration and spray pyrolysis temperature upon hydroxyapatite particle size and density.

    Science.gov (United States)

    Cho, Jung Sang; Lee, Jeong-Cheol; Rhee, Sang-Hoon

    2016-02-01

    In the synthesis of hydroxyapatite powders by spray pyrolysis, control of the particle size was investigated by varying the initial concentration of the precursor solution and the pyrolysis temperature. Calcium phosphate solutions (Ca/P ratio of 1.67) with a range of concentrations from 0.1 to 2.0 mol/L were prepared by dissolving calcium nitrate tetrahydrate and diammonium hydrogen phosphate in deionized water and subsequently adding nitric acid. Hydroxyapatite powders were then synthesized by spray pyrolysis at 900°C and at 1500°C, using these calcium phosphate precursor solutions, under the fixed carrier gas flow rate of 10 L/min. The particle size decreased as the precursor concentration decreased and the spray pyrolysis temperature increased. Sinterability tests conducted at 1100°C for 1 h showed that the smaller and denser the particles were, the higher the relative densities were of sintered hydroxyapatite disks formed from these particles. The practical implication of these results is that highly sinterable small and dense hydroxyapatite particles can be synthesized by means of spray pyrolysis using a low-concentration precursor solution and a high pyrolysis temperature under a fixed carrier gas flow rate. © 2015 Wiley Periodicals, Inc.

  17. Surface Induced Dissociation Yields Quaternary Substructure of Refractory Noncovalent Phosphorylase B and Glutamate Dehydrogenase Complexes

    Science.gov (United States)

    Ma, Xin; Zhou, Mowei; Wysocki, Vicki H.

    2014-03-01

    Ion mobility (IM) and tandem mass spectrometry (MS/MS) coupled with native MS are useful for studying noncovalent protein complexes. Collision induced dissociation (CID) is the most common MS/MS dissociation method. However, some protein complexes, including glycogen phosphorylase B kinase (PHB) and L-glutamate dehydrogenase (GDH) examined in this study, are resistant to dissociation by CID at the maximum collision energy available in the instrument. Surface induced dissociation (SID) was applied to dissociate the two refractory protein complexes. Different charge state precursor ions of the two complexes were examined by CID and SID. The PHB dimer was successfully dissociated to monomers and the GDH hexamer formed trimeric subcomplexes that are informative of its quaternary structure. The unfolding of the precursor and the percentages of the distinct products suggest that the dissociation pathways vary for different charge states. The precursors at lower charge states (+21 for PHB dimer and +27 for GDH hexamer) produce a higher percentage of folded fragments and dissociate more symmetrically than the precusors at higher charge states (+29 for PHB dimer and +39 for GDH hexamer). The precursors at lower charge state may be more native-like than the higher charge state because a higher percentage of folded fragments and a lower percentage of highly charged unfolded fragments are detected. The combination of SID and charge reduction is shown to be a powerful tool for quaternary structure analysis of refractory noncovalent protein complexes, as illustrated by the data for PHB dimer and GDH hexamer.

  18. Palladium Catalyzed Heck Arylation of 2,3-Dihydrofuran—Effect of the Palladium Precursor

    Directory of Open Access Journals (Sweden)

    Adam Morel

    2014-06-01

    Full Text Available Heck arylation of 2,3-dihydrofuran with iodobenzene was carried out in systems consisting of different palladium precursors (Pd2(dba3, Pd(acac2, PdCl2(cod, [PdCl(allyl]2, PdCl2(PhCN2, PdCl2(PPh32 and ionic liquids (CILs with L-prolinate or L-lactate anions. All the tested CILs caused remarkable increases of the conversion values and in all of the reactions 2-phenyl-2,3-dihydrofuran (3 was obtained as the main product with a yield of up to 59.2%. The highest conversions of iodobenzene were achieved for the [PdCl(allyl]2 precursor. Formation of Pd(0 nanoparticles, representing the resting state of the catalyst, was evidenced by TEM.

  19. Effect of precursor concentration on the growth of zinc oxide nanorod arrays on pre-treated substrates

    International Nuclear Information System (INIS)

    Urgessa, Z.N.; Oluwafemi, O.S.; Botha, J.R.

    2012-01-01

    Well aligned zinc oxide nanorod arrays (ZNAs) synthesized by a simple chemical bath deposition method were fabricated on pre-treated Si substrates. By keeping the molar VI/II ratio constant, the effect of precursor concentration on the growth and optical quality of the ZNAs was investigated. The as-synthesized ZNAs were characterized by field emission scanning electron microscopy (FESEM), x-ray diffraction (XRD) and photoluminescence spectroscopy (PL). FESEM images show that both the diameter and aspect ratio of the ZNAs increase dramatically as the precursor concentration increases. The XRD analysis indicates that all the as-grown ZNAs are crystalline and are preferentially oriented along the c-axis. The high intensity ratio of the UV emission to visible emission in the room temperature PL spectra illustrate that high optical quality ZNAs were produced.

  20. Effect of precursor concentration on the growth of zinc oxide nanorod arrays on pre-treated substrates

    Energy Technology Data Exchange (ETDEWEB)

    Urgessa, Z.N. [Department of Physics, P.O. Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa); Oluwafemi, O.S., E-mail: oluwafemi.oluwatobi@gmail.com [Department of Chemistry and Chemical Technology, Walter Sisulu University, Mthatha Campus, Private Bag XI, 5117 (South Africa); Botha, J.R. [Department of Physics, P.O. Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa)

    2012-05-15

    Well aligned zinc oxide nanorod arrays (ZNAs) synthesized by a simple chemical bath deposition method were fabricated on pre-treated Si substrates. By keeping the molar VI/II ratio constant, the effect of precursor concentration on the growth and optical quality of the ZNAs was investigated. The as-synthesized ZNAs were characterized by field emission scanning electron microscopy (FESEM), x-ray diffraction (XRD) and photoluminescence spectroscopy (PL). FESEM images show that both the diameter and aspect ratio of the ZNAs increase dramatically as the precursor concentration increases. The XRD analysis indicates that all the as-grown ZNAs are crystalline and are preferentially oriented along the c-axis. The high intensity ratio of the UV emission to visible emission in the room temperature PL spectra illustrate that high optical quality ZNAs were produced.

  1. Elicitation with methyl jasmonate supported by precursor feeding with phenylalanine: Effect on Garnacha grape phenolic content.

    Science.gov (United States)

    Portu, Javier; López, Rosa; Santamaría, Pilar; Garde-Cerdán, Teresa

    2017-12-15

    Recent works showed that elicitation, supported by precursor feeding, could be a strategy to increase phenolic content. However, these studies have never been conducted in viticulture. This strategy could be of greater interest in Garnacha, a grape variety characterized by its low phenolic content. Therefore, this work studied elicitation with methyl jasmonate (MeJ), supported by precursor feeding with phenylalanine (Phe), in order to improve Garnacha grape phenolic content. Results showed that Phe+MeJ treatment did not improve phenolic content to a greater extent than the corresponding individual treatments. Overall, the greatest improvement was obtained with MeJ application, followed by Phe+MeJ; while Phe treatment barely increased phenolic compounds. Consequently, it was not possible to confirm the hypothesis that elicitation by MeJ could be supported by precursor feeding with Phe, when both applied together. This is the first study dealing with this matter under field conditions serving as basis for future works. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Effect of aromatic precursor addition to wine fermentations carried out with different Saccharomyces species and their hybrids.

    Science.gov (United States)

    Gamero, Amparo; Hernández-Orte, Purificación; Querol, Amparo; Ferreira, Vicente

    2011-05-14

    This work explores the ability of different yeast strains from different species of the genus Saccharomyces (S. cerevisiae, S. uvarum and S. kudriavzevii) and hybrids between these species to release or form varietal aroma compounds from fractions of grape odourless precursors. The de novo synthesis by the yeasts of some of the varietal aroma compounds was also evaluated. The study has shown that de novo synthesis affects some lipid derivatives, shikimic derivatives and terpenes in all species and hybrids, with some remarkable differences amongst them. The release or formation of aroma compounds from precursors was found to be strongly linked to the yeast or hybrid used, and the triple hybrid S. cerevisiae × S. bayanus × S. kudriavzevii in particular and secondarily the hybrid S. cerevisiae × S. bayanus were highly efficient in the production of most varietal aroma compounds, including γ-lactones, benzenoids, volatile phenols, vanillin derivatives and terpenols. The presence of precursors in the fermenting media caused a surprising levelling effect on the fermentative aroma composition. Altogether, these results suggest that it is possible to modulate wine aroma by employing different yeast species in order to create new wines with different aromatic notes. Copyright © 2011 Elsevier B.V. All rights reserved.

  3. Effect of precursor supply on structural and morphological characteristics of fe nanomaterials synthesized via chemical vapor condensation method.

    Science.gov (United States)

    Ha, Jong-Keun; Ahn, Hyo-Jun; Kim, Ki-Won; Nam, Tae-Hyun; Cho, Kwon-Koo

    2012-01-01

    Various physical, chemical and mechanical methods, such as inert gas condensation, chemical vapor condensation, sol-gel, pulsed wire evaporation, evaporation technique, and mechanical alloying, have been used to synthesize nanoparticles. Among them, chemical vapor condensation (CVC) has the benefit of its applicability to almost all materials because a wide range of precursors are available for large-scale production with a non-agglomerated state. In this work, Fe nanoparticles and nanowires were synthesized by chemical vapor condensation method using iron pentacarbonyl (Fe(CO)5) as the precursor. The effect of processing parameters on the microstructure, size and morphology of Fe nanoparticles and nanowires were studied. In particular, we investigated close correlation of size and morphology of Fe nanoparticles and nanowires with atomic quantity of inflow precursor into the electric furnace as the quantitative analysis. The atomic quantity was calculated by Boyle's ideal gas law. The Fe nanoparticles and nanowires with various diameter and morphology have successfully been synthesized by the chemical vapor condensation method.

  4. Photocatalytic deposition of Ag nanoparticles on TiO2: Metal precursor effect on the structural and photoactivity properties

    Directory of Open Access Journals (Sweden)

    E. Albiter

    2015-09-01

    Full Text Available A series of 1 wt.% Ag–TiO2 photocatalysts were obtained by photodeposition using different organic (acetylacetonate, Ag-A and inorganic (nitrate, Ag-N, and perchlorate, Ag-C silver precursors in order to determinate the influence of the silver precursor on final properties of the photocatalysts. The resulting photocatalytic materials were characterized by different techniques (UV–Vis DRS, TEM/HRTEM and XPS and their photocatalytic activity was evaluated in the degradation of rhodamine B (used as model pollutant in aqueous solution under simulated solar light. The photocatalytic reduction of Ag species to Ag0 on TiO2 was higher with silver nitrate as precursor compared to acetylacetonate or perchlorate. All the Ag-modified TiO2 photocatalysts exhibited a surface plasmon resonance effect in the visible region (400–530 nm indicating different metal particle sizes depending on the Ag precursor used in their synthesis. A higher photocatalytic activity was obtained with all the Ag/TiO2 samples compared with non-modified TiO2. The descending order of photocatalytic activity was as follows: Ag-A/TiO2 ≈ Ag-N/TiO2 > Ag-C/TiO2 > TiO2-P25. The enhanced photoactivity was attributed to the presence of different amounts Ag0 nanoparticles homogeneously distributed on Ag2O and TiO2, trapping the photogenerated electrons and avoiding charge recombination.

  5. Crude glycerol as glycogenic precursor in feed; effects on milk coagulation properties and metabolic profiles of dairy cows.

    Science.gov (United States)

    Harzia, Hedi; Kilk, Kalle; Ariko, Tiia; Kass, Marko; Soomets, Ursel; Jõudu, Ivi; Kaart, Tanel; Arney, David; Kärt, Olav; Ots, Meelis

    2013-05-01

    As grain prices rise, the search for alternative glycogenic precursors in animal feed becomes increasingly important, and this study was conducted to determine if the replacement of starch with glycerol, as an alternative glycogenic precursor, affects the milk metabolic profile and milk coagulation ability, and therefore the quality of the milk. Eight primiparous mid-lactation Holstein cows were fed during a replicated 4 × 4 Latin square trial with four different isoenergetic rations: (1) control (T0) fed a total mixed ration (TMR) with barley meal; (2) group T1, decreased barley content, replaced isoenergetically with 1 kg crude glycerol; (3) group T2, the barley meal was replaced with 2 kg of crude glycerol; and (4) group T3 the barley meal was replaced with 3 kg of crude glycerol. Rumen, blood and milk samples were collected at the end of every 21-d treatment period. Rumen samples were analysed for proportion of total volatile fatty acid (VFA), blood samples for insulin and glucose, and milk for metabolites (e.g. citric-acid cycle compounds). The change in glycogenic precursors had a positive effect on rumen VFA proportions; the proportion of propionic acid increased (P Milk protein (P milk protein concentration may have been due to an increase in microbial protein. Regarding the milk metabolic profiles, different signals were positively associated with coagulation ability and change in the diet. Based on this study, changing the glycogenic precursor in animal diet in this way is possible, and may have no immediate deleterious consequences on milk quality or cow health. Indeed, there is evidence for benefits from this substitution.

  6. Thermoset precursor

    International Nuclear Information System (INIS)

    Yamamoto, Y.

    1983-04-01

    This invention pertains to a distinctive thermoset precursor which is prepared by mixing a resin composition (A) which can be hardened by ionizing radiation, and a resin composition (B) which can be hardened by heat but cannot be hardened by, or is resistant to, ionizing radiation, and by coating or impregnating a molding or other substrate with a sheet or film of this mixture and irradiating this with an ionizing radiation. The principal components of composition (A) and (B) can be the following: (1) an acrylate or methacrylate and an epoxy resin and an epoxy resin hardener; (2) an unsaturated polyester resin and epoxy resin and an epoxy resin hardener; (3) a diacrylate or dimethacrylate or polyethylene glycol and an epoxy resin; (4) an epoxy acrylates or epoxy methacrylate obtained by the addition reaction of epoxy resin and acrylic or methacrylic acid

  7. Plant sterols, cholesterol precursors and oxysterols: Minute concentrations-Major physiological effects.

    Science.gov (United States)

    Olkkonen, Vesa M; Gylling, Helena; Ikonen, Elina

    2017-05-01

    Non-cholesterol sterols are present in our body at very low concentrations as compared to cholesterol. Small changes in the structure of sterol molecules confer them highly distinct biological activities. The best-known example are steroid hormones derived from cholesterol. During the past decade, our knowledge of also other biomolecules related to or derived from cholesterol, particularly plant sterols, biosynthetic precursors of cholesterol, and oxysterols, has expanded rapidly. In this review article we recapitulate the latest insights into the properties and physiological activities of these non-cholesterol sterols, as well as their importance in disease processes and potential as diagnostic biomarkers. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. New Approach for Studying Slow Fragmentation Kinetics in FT-ICR: Surface-Induced Dissociation Combined with Resonant Ejection

    Energy Technology Data Exchange (ETDEWEB)

    Laskin, Julia; Futrell, Jean H.

    2015-02-01

    We introduce a new approach for studying the kinetics of large ion fragmentation in the gas phase by coupling surface-induced dissociation (SID) in a Fourier transform ion cyclotron resonance mass spectrometer with resonant ejection of selected fragment ions using a relatively short (5 ms) ejection pulse. The approach is demonstrated for singly protonated angiotensin III ions excited by collisions with a self-assembled monolayer of alkylthiol on gold (HSAM). The overall decomposition rate and rate constants of individual reaction channels are controlled by varying the kinetic energy of the precursor ion in a range of 65–95 eV. The kinetics of peptide fragmentation are probed by varying the delay time between resonant ejection and fragment ion detection at a constant total reaction time. RRKM modeling indicates that the shape of the kinetics plots is strongly affected by the shape and position of the energy deposition function (EDF) describing the internal energy distribution of the ion following ion-surface collision. Modeling of the kinetics data provides detailed information on the shape of the EDF and energy and entropy effects of individual reaction channels.

  9. Effects of Maternal Supplementation With Omega-3 Precursors on Human Milk Composition.

    Science.gov (United States)

    Mazurier, Evelyne; Rigourd, Virginie; Perez, Paul; Buffin, Rachel; Couedelo, Leslie; Vaysse, Carole; Belcadi, Wafae; Sitta, Rémi; Nacka, Fabienne; Lamireau, Delphine; Cambonie, Gilles; Picaud, Jean-Charles; Billeaud, Claude

    2017-05-01

    Long-chain polyunsaturated fatty acids (LC-PUFAs) are important for newborn neurosensory development. Supplementation of breastfeeding mothers' diets with omega-3 PUFAs, such as alpha-linolenic acid (ALA), may increase their concentration in human milk. Research aim: This study aimed to assess human milk composition after 15-day supplementation regimens containing either omega-3 PUFAs or olive oil, which does not provide ALA. A multicenter factorial randomized trial was conducted with four groups of breastfeeding women, with each group containing 19 to 22 women. After a 15-day ALA washout period, three groups received supplementation with omega-3 precursors for 15 days: an enriched margarine (M), a rapeseed oil (R), and a margarine and rapeseed oil (MR). The fourth was unexposed to omega-3 precursors (olive oil control diet, O). After 15 days, blind determination of human milk fatty acid (FA) composition was assessed by gas chromatography, and the FA composition was compared among groups using variance analyses. Alpha-linolenic acid content, expressed as the mean (standard deviation) total human milk FA percentage, was significantly higher after diet supplementation with omega-3 PUFAs, with values of 2.2% (0.7%) (MR), 1.3% (0.5%) (R), 1.1% (0.4%) (M), and 0.8% (0.3%) (O at D30) ( p human milk and generated the most favorable LA-ALA ratio for LC-PUFA synthesis.

  10. Effects of Amyloid Precursor Protein 17 Peptide on the Protection of Diabetic Encephalopathy and Improvement of Glycol Metabolism in the Diabetic Rat

    OpenAIRE

    Meng, Heng; Zhang, Duo; Yang, Haishan

    2013-01-01

    Researchers have proposed that amyloid precursor protein 17 peptide (APP17 peptide), an active fragment of amyloid precursor protein (APP) in the nervous system, has therapeutic effects on neurodegeneration. Diabetic encephalopathy (DE) is a neurological disease caused by diabetes. Here we use multiple experimental approaches to investigate the effect of APP17 peptide on changes in learning behavior and glycol metabolism in rats. It was found that rats with DE treated by APP17 peptide showed ...

  11. The effect of Nb doping on ferroelectric properties of PZT thin films prepared from polymeric precursors

    International Nuclear Information System (INIS)

    Souza, E.C.F.; Simoes, A.Z.; Cilense, M.; Longo, E.; Varela, J.A.

    2004-01-01

    Pure and Nb doped PbZr 0.4 Ti 0.6 O 3 thin films was prepared by the polymeric precursor method and deposited by spin coating on Pt/Ti/SiO 2 /Si (100) substrates and annealed at 700 deg. C. The films are oriented in (1 1 0) and (1 0 0) direction. The electric properties of PZT thin films show strong dependence of the crystallographic orientation. The P-E hysteresis loops for the thin film with composition PbZr 0.39 Ti 0.6 Nb 0.1 O 3 showed good saturation, with values for coercive field (E c ) equal to 60 KV cm -1 and for remanent polarization (P r ) equal to 20 μC cm -2 . The measured dielectric constant (ε) is 1084 for this film. These results show good potential for application in FERAM

  12. Effect of precursor choice and sintering conditions for W hexaferrite formation

    DEFF Research Database (Denmark)

    Mørch, Mathias; Eikeland, Anna; Christensen, Mogens

    . This is believed to be caused not just by super-exchange coupling across one oxygen (Fe-O-Fe) but super-super-exchange across two oxygens (Fe-O-O-Fe). The unit cell is rather complex with dimensions of a=b= 5.91 Å and c= 32.75 Å. In this work, SrZn2Fe16O27 was synthesized by a sol-gel autocombustion synthesis...... method using metal nitrates, citric acid and concentrated ammonia to prepare the precursor gel. The gel was sintered at four different sintering temperatures (1000, 1100, 1200, and 1300 ˚C) for two hours in a conventional oven. Almost phase pure SrZn2Fe16O27 was formed at temperatures above 1200 ˚C...

  13. Thermo-radiosensitivity of the granulocyte and macrophage precursor cells of mice. II. - X irradiation effects and influence of hyperthermia on the radiosensitivity

    International Nuclear Information System (INIS)

    Bueren, J.A.; Nieto, M.

    1983-01-01

    The effects of the X-irradiation on the viability of the granulocyte-macrophage precursors, has been determined by means of the agar diffusion chamber culture technique. The results show the high radiosensitivity of these cells, with survival parameter similar to those previously reported in the literature about different granulocyte-macrophage precursors. When a hyperthermic treatment is performed prior to the X-irradiation, a radiosensitization phenomenon is observed due to the synergism existent between hyperthermia and X rays on the lethality of the precursors. (Authors) 37 refs

  14. Enhanced proliferation and dopaminergic differentiation of ventral mesencephalic precursor cells by synergistic effect of FGF2 and reduced oxygen tension

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Pia [Department of Neurobiology Research, Institute of Molecular Medicine, University of Southern Denmark, Winslowparken 21, DK-5000 Odense C (Denmark); Department of Neurosurgery, University of Bern, CH-3010 Bern (Switzerland); Gramsbergen, Jan-Bert; Zimmer, Jens [Department of Neurobiology Research, Institute of Molecular Medicine, University of Southern Denmark, Winslowparken 21, DK-5000 Odense C (Denmark); Widmer, Hans R. [Department of Neurosurgery, University of Bern, CH-3010 Bern (Switzerland); Meyer, Morten, E-mail: MMeyer@health.sdu.dk [Department of Neurobiology Research, Institute of Molecular Medicine, University of Southern Denmark, Winslowparken 21, DK-5000 Odense C (Denmark)

    2011-07-15

    Effective numerical expansion of dopaminergic precursors might overcome the limited availability of transplantable cells in replacement strategies for Parkinson's disease. Here we investigated the effect of fibroblast growth factor-2 (FGF2) and FGF8 on expansion and dopaminergic differentiation of rat embryonic ventral mesencephalic neuroblasts cultured at high (20%) and low (3%) oxygen tension. More cells incorporated bromodeoxyuridine in cultures expanded at low as compared to high oxygen tension, and after 6 days of differentiation there were significantly more neuronal cells in low than in high oxygen cultures. Low oxygen during FGF2-mediated expansion resulted also in a significant increase in tyrosine hydroxylase-immunoreactive (TH-ir) dopaminergic neurons as compared to high oxygen tension, but no corresponding effect was observed for dopamine release into the culture medium. However, switching FGF2-expanded cultures from low to high oxygen tension during the last two days of differentiation significantly enhanced dopamine release and intracellular dopamine levels as compared to all other treatment groups. In addition, the short-term exposure to high oxygen enhanced in situ assessed TH enzyme activity, which may explain the elevated dopamine levels. Our findings demonstrate that modulation of oxygen tension is a recognizable factor for in vitro expansion and dopaminergic differentiation of rat embryonic midbrain precursor cells.

  15. Thermo-radiosensitivity of the granulocyte and macrophage precursor cells of mice. I.-Development of the in vivo culture and effects induced by the hyperthermia

    International Nuclear Information System (INIS)

    Bueren, J. A.; Nieto, M.

    1983-01-01

    The present report shows the agar diffusion chamber technique for culturing granulocyte- macrophage precursor cells, obtained from mice bone marrow. Diffusion chambers containing the bone marrow suspension are implanted intraperitoneally Into mice and constitute a compartment which avoids the migration of cells, but allows the transit of the mouse biological fluxes, necessary for the cellular proliferation. By means of this technique, we studied the lethal effects of the hyperthermia on the precursors and their capacity to repair sublethal damage. (Author) 129 refs

  16. Effect of precursor concentration on physical properties of nebulized spray deposited In2S3 thin films

    Directory of Open Access Journals (Sweden)

    J. Raj Mohamed

    2016-09-01

    Full Text Available The present work investigates the effect of precursor concentration (mc on the structural, optical, morphological and electrical conductivity properties of In2S3 thin films grown on amorphous glass substrates by nebulized spray pyrolysis (NSP technique. The mixed phase of cubic and tetragonal structure of In2S3 thin films at higher concentration has been observed by X-ray diffraction pattern. The reduced strain by increasing the precursor concentration increased the average crystallite from 17.8 to 28.9 nm. The energy dispersive analysis by X-ray (EDAX studies confirmed the presence of In and S. The transmittance, optical direct band gap energy, Urbach energy and skin depth of In2S3 films have been analyzed by optical absorption spectra. The better conductivity and mobility noticed at mc = 0.15 M are explained by carrier concentration and crystallite. Better optical and electrical conductivity behaviour of In2S3 thin film sample proposes for effective solar cell fabrication.

  17. Effective reduction in the nanoparticle sizes of NiO obtained via the pyrolysis of nickel malonate precursor modified using oleylamine surfactant

    Energy Technology Data Exchange (ETDEWEB)

    Lontio Fomekong, Roussin, E-mail: lonforou@yahoo.fr [Chemistry Department, Higher Teacher Training College, University of Yaoundé I, B.P. 47, Yaoundé (Cameroon); Institut de la Matière Condensée et des Nanosciences, Université Catholique de Louvain, Croix du Sud 1, 1348 Louvain-La-Neuve (Belgium); Ngolui Lambi, John; Ebede, Guy Roland [Chemistry Department, Higher Teacher Training College, University of Yaoundé I, B.P. 47, Yaoundé (Cameroon); Kenfack Tsobnang, Patrice [Chemistry Department, University of Dschang, PO Box 96, Dschang (Cameroon); Tedjieukeng Kamta, Hypolite Mathias; Ngnintedem Yonti, Cedrik [Chemistry Department, Higher Teacher Training College, University of Yaoundé I, B.P. 47, Yaoundé (Cameroon); Delcorte, Arnaud [Institut de la Matière Condensée et des Nanosciences, Université Catholique de Louvain, Croix du Sud 1, 1348 Louvain-La-Neuve (Belgium)

    2016-09-15

    Nickel oxide nanoparticles were synthesized via thermal decomposition of two precursors, the first, a simple nickel malonate and the second, a nickel malonate modified by oleylamine, a surfactant, both having been synthesized by precipitation. While FTIR, TGA and ToF-SIMS were used to characterize the two precursors and to show the presence of oleylamine in the modified precursor, XRD, SEM, TEM and BET were employed to investigate the structure, the morphology and the specific surface area of the decomposition products obtained after pyrolysis. The results showed that the modification of nickel malonate by oleylamine was effective. The XRD results, which showed a cubic structure for the NiO obtained, suggest with SEM an important particle size reduction (at least 54%) when oleylamine was used to modify the nickel malonate precursor. The SEM images also showed a well-defined spherical nanoparticle morphology in both cases, not affected by the presence of oleylamine. The TEM also confirmed the reduction of particle size and their spherical nature but at the same time showed that, in the presence of oleylamine, there was no agglomeration resulting in a more uniform particle size distribution. The specific surface area of the NiO obtained by the oleylamine-modified precursor was 4.7 times larger than that obtained with the regular precursor. This again confirms the particle size reduction. - Highlights: • Nickel malonate precursor has been synthesized by precipitation method. • This precursor was successfully modified by a surfactant (oleylamine). • NiO was identified as the decomposition products of the previous precursors. • Oleylamine has provoked around 54% of particle size reduction of the NiO.

  18. Fe-Impregnated Mineral Colloids for Peroxide Activation: Effects of Mineral Substrate and Fe Precursor.

    Science.gov (United States)

    Li, Yue; Machala, Libor; Yan, Weile

    2016-02-02

    Heterogeneous iron species at the mineral/water interface are important catalysts for the generation of reactive oxygen species at circumneutral pH. One significant pathway leading to the formation of such species arises from deposition of dissolved iron onto mineral colloids due to changes in redox conditions. This study investigates the catalytic properties of Fe impregnated on silica, alumina, and titania nanoparticles (as prototypical mineral colloids). Fe impregnation was carried out by immersing the mineral nanoparticles in dilute Fe(II) or Fe(III) solutions at pH 6 and 3, respectively, in an aerobic environment. The uptake of iron per unit surface area follows the order of nTiO2 > nAl2O3 > nSiO2 for both types of Fe precursors. Impregnation of mineral particles in Fe(II) solutions results in predominantly Fe(III) species due to efficient surface-mediated oxidation. The catalytic activity of the impregnated solids to produce hydroxyl radical (·OH) from H2O2 decomposition was evaluated using benzoic acid as a probe compound under dark conditions. Invariably, the rates of benzoic acid oxidation with different Fe-laden particles increase with the surface density of Fe until a critical density above which the catalytic activity approaches a plateau, suggesting active Fe species are formed predominantly at low surface loadings. The critical surface density of Fe varies with the mineral substrate as well as the aqueous Fe precursor. Fe impregnated on TiO2 exhibits markedly higher activity than its Al2O3 and SiO2 counterparts. The speciation of interfacial Fe is analyzed with diffuse reflectance UV-vis analysis and interpretation of the data in the context of benzoic oxidation rates suggests that the surface activity of the solids for ·OH generation correlates strongly with the isolated (i.e., mononuclear) Fe species. Therefore, iron dispersed on mineral colloids is a significant form of reactive iron surfaces in the aquatic environment.

  19. The effect of synthesis time on graphene growth from palm oil as green carbon precursor

    Energy Technology Data Exchange (ETDEWEB)

    Salifairus, M. J., E-mail: salifairus-mj85@yahoo.co.uk [NANO-SciTech Centre (NST), Institute of Science, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Faculty of Applied Sciences, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); NANO-ElecTronic Centre - Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Hamid, S. B. Abd [Nanotechnology and Catalysis Research Centre (NANOCAT) Universiti Malaya - UM, 50603 Kuala Lumpur (Malaysia); Alrokayan, Salman A. H.; Khan, Haseeb A. [Department of Biochemistry, College of Science King Saud University (KSU), Riyadh 11451 (Saudi Arabia); Rusop, M., E-mail: nanouitm@gmail.com [NANO-SciTech Centre (NST), Institute of Science, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); NANO-ElecTronic Centre - Faculty of Electrical Engineering, Universiti Teknologi MARA - UiTM, 40450 Shah Alam, Selangor (Malaysia)

    2016-07-06

    Graphene is the new material that arises after carbon nanotubes (CNTs) era and has extraordinary optical, electronic and mechanical properties compared to CNTs. The 2D graphene is the sp{sup 2} carbon allotropes compared to other dimensionality. It also can be in three forms that are zero-dimensional, one-dimensional or three-dimensional. The different dimensionality also called fullerenes, nanotubes and graphite. Therefore, the graphene is known as centre potential materials in expanding research area than others ever. The 2 cm × 2 cm silicon wafer was seeded with nickel (Ni) at different thickness by using sputter coater. The palm oil, carbon source, was placed in the precursor furnace and the silicon was placed in the second furnace (deposition furnace). The palm oil will mix with Nitrogen gas was used as carrier gas in the CVD under certain temperature and pressure to undergo pyrolysis proses. The deposition temperature was set at 1000 °C. The deposition time varied from 3 minutes, 5 minutes and 7 minutes. The graphene was growth at ambient pressure in the CVD system. Electron microscopy and Raman Spectrometer revealed the structural properties and surface morphology of the grapheme on the substrate. The D and G band appear approximately at 1350 cm{sup −1} and 1850 cm{sup −1}. It can be concluded that the growth of graphene varies at different deposition time.

  20. Dutch children at family risk of dyslexia: precursors, reading development, and parental effects.

    Science.gov (United States)

    van Bergen, Elsje; de Jong, Peter F; Regtvoort, Anne; Oort, Frans; van Otterloo, Sandra; van der Leij, Aryan

    2011-02-01

    The study concerns reading development and its precursors in a transparent orthography. Dutch children differing in family risk for dyslexia were followed from kindergarten through fifth grade. In fifth grade, at-risk dyslexic (n = 22), at-risk non-dyslexic (n = 45), and control children (n = 12) were distinguished. In kindergarten, the at-risk non-dyslexics performed better than the at-risk dyslexics, but worse than the controls on letter-knowledge and rapid naming. The groups did not differ on phonological awareness. At-risk dyslexics read less fluently from first grade onwards than the other groups. At-risk non-dyslexics' reading fluency was at an intermediate position between the other groups at the start of reading. By fifth grade they had reached a similar level as the controls on word reading, but still lagged behind on pseudoword reading. Results further showed that the parents of the groups of at-risk children differed in educational level and reading skills. Overall, the groups of at-risk children differed on pre-reading skills as well as on reading development. These differences do not seem to stem from differences in intellectual abilities or literacy environment. Instead, the better reading skills of parents of at-risk non-dyslexics suggest that these children might have a lower genetic liability. Copyright © 2010 John Wiley & Sons, Ltd.

  1. The effect of synthesis time on graphene growth from palm oil as green carbon precursor

    International Nuclear Information System (INIS)

    Salifairus, M. J.; Hamid, S. B. Abd; Alrokayan, Salman A. H.; Khan, Haseeb A.; Rusop, M.

    2016-01-01

    Graphene is the new material that arises after carbon nanotubes (CNTs) era and has extraordinary optical, electronic and mechanical properties compared to CNTs. The 2D graphene is the sp 2 carbon allotropes compared to other dimensionality. It also can be in three forms that are zero-dimensional, one-dimensional or three-dimensional. The different dimensionality also called fullerenes, nanotubes and graphite. Therefore, the graphene is known as centre potential materials in expanding research area than others ever. The 2 cm × 2 cm silicon wafer was seeded with nickel (Ni) at different thickness by using sputter coater. The palm oil, carbon source, was placed in the precursor furnace and the silicon was placed in the second furnace (deposition furnace). The palm oil will mix with Nitrogen gas was used as carrier gas in the CVD under certain temperature and pressure to undergo pyrolysis proses. The deposition temperature was set at 1000 °C. The deposition time varied from 3 minutes, 5 minutes and 7 minutes. The graphene was growth at ambient pressure in the CVD system. Electron microscopy and Raman Spectrometer revealed the structural properties and surface morphology of the grapheme on the substrate. The D and G band appear approximately at 1350 cm −1 and 1850 cm −1 . It can be concluded that the growth of graphene varies at different deposition time.

  2. Effect of time and of precursor molecule on the deposition of hydrophobic nanolayers on ethyelene tetrafluoroethylene–silicon oxide substrates

    Directory of Open Access Journals (Sweden)

    Gabriella Rossi

    2016-01-01

    Full Text Available Abstract A method was developed for generating transparent and hydrophobic nanolayers chemisorbed onto flexible substrates of ethylene tetrafluoroethylene–silicon oxide (ETFE–SiOx. In particular, the effect of the deposition time and of the precursor molecule on the nanocoating process was analyzed with the aim of pursuing an optimization of the above method in an industrial application perspective. It was found that precursor molecule of triethoxysilane allowed to obtain better hydrophobic properties on the SiOx surface in shorter times compared to trichlorosilane, reaching the 92 % of final contact angle (CA value of 106° after only 1 h of deposition. The optical properties and surface morphology were also assessed in function of time, revealing that an initial transparency reduction is followed by a subsequent transmittance increase during the self assembly of fluoroalkylsilanes on the SiOx surface, coherently with the surface roughness analysis data. Encouraging results were also obtained in terms of oleophobic properties improvement of the nanocoated surfaces.

  3. Enhanced proliferation and dopaminergic differentiation of ventral mesencephalic precursor cells by synergistic effect of FGF2 and reduced oxygen tension

    DEFF Research Database (Denmark)

    Jensen, Pia; Gramsbergen, Jan-Bert; Zimmer, Jens

    2011-01-01

    Effective numerical expansion of dopaminergic precursors might overcome the limited availability of transplantable cells in replacement strategies for Parkinson's disease. Here we investigated the effect of fibroblast growth factor-2 (FGF2) and FGF8 on expansion and dopaminergic differentiation...... of rat embryonic ventral mesencephalic neuroblasts cultured at high (20%) and low (3%) oxygen tension. More cells incorporated bromodeoxyuridine in cultures expanded at low as compared to high oxygen tension, and after 6 days of differentiation there were significantly more neuronal cells in low than......, switching FGF2-expanded cultures from low to high oxygen tension during the last two days of differentiation significantly enhanced dopamine release and intracellular dopamine levels as compared to all other treatment groups. In addition, the short-term exposure to high oxygen enhanced in situ assessed TH...

  4. Effect of the calcining temperature on the porosity of the titanium dioxide powders obtained by Polymeric Precursor Method

    International Nuclear Information System (INIS)

    Silva, D.W.; Granado, S.R.; Ciola, R.A.; Cavalheiro, A.A.

    2011-01-01

    Ceramics materials obtained by Polymeric Precursor Method exhibit mechanisms of the pore formation and elimination dependents on the decomposition kinetics of the residual organic matter of the polyester. The mechanism of pore elimination seems to occur by disrupting of the wall among the pores because it leads to the consequent pore coalescence and increasing in pore volume, which posses higher pore diameters. In this case, it was observed that the porosity decreasing occurs by pore wall moving after that the residual organic matter is eliminated from the pore inside. The pore diameter associated to the highest volume desorption occurred for the material obtained after calcining at 450°C is approximately 1,7 nm, what seems to be related to the amorphous carbon accumulated inside the pores, once that the pore volume decreases more effectively for the material obtained by calcining at 550°C, making the maximum volume situates at 2,0 nm. (author)

  5. [ORION®: a simple and effective method for systemic analysis of clinical events and precursors occurring in hospital practice].

    Science.gov (United States)

    Debouck, F; Rieger, E; Petit, H; Noël, G; Ravinet, L

    2012-05-01

    Morbimortality review is now recommended by the French Health Authority (Haute Autorité de santé [HAS]) in all hospital settings. It could be completed by Comités de retour d'expérience (CREX), making systemic analysis of event precursors which may potentially result in medical damage. As commonly captured by their current practice, medical teams may not favour systemic analysis of events occurring in their setting. They require an easy-to-use method, more or less intuitive and easy-to-learn. It is the reason why ORION(®) has been set up. ORION(®) is based on experience acquired in aeronautics which is the main precursor in risk management since aircraft crashes are considered as unacceptable even though the mortality from aircraft crashes is extremely low compared to the mortality from medical errors in hospital settings. The systemic analysis is divided in six steps: (i) collecting data, (ii) rebuilding the chronology of facts, (iii) identifying the gaps, (iv) identifying contributing and influential factors, (v) proposing actions to put in place, (vi) writing the analysis report. When identifying contributing and influential factors, four kinds of factors favouring the event are considered: technical domain, working environment, organisation and procedures, human factors. Although they are essentials, human factors are not always considered correctly. The systemic analysis is done by a pilot, chosen among people trained to use the method, querying information from all categories of people acting in the setting. ORION(®) is now used in more than 400 French hospital settings for systemic analysis of either morbimortality cases or event precursors. It is used, in particular, in 145 radiotherapy centres for supporting CREX. As very simple to use and quasi-intuitive, ORION(®) is an asset to reach the objectives defined by HAS: to set up effective morbi-mortality reviews (RMM) and CREX for improving the quality of care in hospital settings. By helping the

  6. EFFECT OF PRECURSOR LOADING ON THE SYNTHESIS RATE AND RELEASE OF DOPAMINE AND SEROTONIN IN THE STRIATUM - A MICRODIALYSIS STUDY IN CONSCIOUS RATS

    NARCIS (Netherlands)

    WESTERINK, BHC; DEVRIES, JB

    The effects of systemic administration of tyrosine and phenylalanine on the extracellular levels of tyrosine and dopamine were determined by microdialysis in the striatum of awake rats. In addition, the effects of these precursors on in vivo 3,4-dihydroxyphenylalanine (DOPA) formation were

  7. Effect of Oxylipins, Terpenoid Precursors and Wounding on Soft Corals’ Secondary Metabolism as Analyzed via UPLC/MS and Chemometrics

    Directory of Open Access Journals (Sweden)

    Mohamed A. Farag

    2017-12-01

    Full Text Available The effect of three oxylipin analogues, a terpenoid intermediate and wounding on the secondary metabolism of the soft corals Sarcophyton glaucum and Lobophyton pauciflorum was assessed. Examined oxylipins included prostaglandin (PG-E1, methyl jasmonate (MeJA, and arachidonic acid (AA in addition to the diterpene precursor geranylgeranylpyrophosphate (GGP. Post-elicitation, metabolites were extracted from coral heads and analyzed via UPLC-MS followed by multivariate data analyses. Both supervised and unsupervised data analyses were used for sample classification. Multivariate data analysis revealed clear segregation of PG-E1 and MeJA elicited S. glaucum at 24 and 48 h post elicitation from other elicitor samples and unelicited control group. PG-E1 was found more effective in upregulating S. glaucum terpene/sterol levels compared to MeJA. Metabolites showing upregulation in S. glaucum include campestene-triol and a cembranoid, detected at ca. 30- and 2-fold higher levels compared to unelicited corals. Such an elicitation effect was less notable in the other coral species L. pauciflorum, suggesting a differential oxylipin response in soft corals. Compared to MeJA and PG, no elicitation effect was observed for GGP, AA or wounding on the metabolism of either coral species.

  8. Effect of Oxylipins, Terpenoid Precursors and Wounding on Soft Corals' Secondary Metabolism as Analyzed via UPLC/MS and Chemometrics.

    Science.gov (United States)

    Farag, Mohamed A; Westphal, Hildegard; Eissa, Tarek F; Wessjohann, Ludger A; Meyer, Achim

    2017-12-10

    The effect of three oxylipin analogues, a terpenoid intermediate and wounding on the secondary metabolism of the soft corals Sarcophyton glaucum and Lobophyton pauciflorum was assessed. Examined oxylipins included prostaglandin (PG-E1), methyl jasmonate (MeJA), and arachidonic acid (AA) in addition to the diterpene precursor geranylgeranylpyrophosphate (GGP). Post-elicitation, metabolites were extracted from coral heads and analyzed via UPLC-MS followed by multivariate data analyses. Both supervised and unsupervised data analyses were used for sample classification. Multivariate data analysis revealed clear segregation of PG-E1 and MeJA elicited S. glaucum at 24 and 48 h post elicitation from other elicitor samples and unelicited control group. PG-E1 was found more effective in upregulating S. glaucum terpene/sterol levels compared to MeJA. Metabolites showing upregulation in S. glaucum include campestene-triol and a cembranoid, detected at ca. 30- and 2-fold higher levels compared to unelicited corals. Such an elicitation effect was less notable in the other coral species L. pauciflorum, suggesting a differential oxylipin response in soft corals. Compared to MeJA and PG, no elicitation effect was observed for GGP, AA or wounding on the metabolism of either coral species.

  9. Effect of histones on hematopoietic stem cells-precursor in normal and irradiated organism

    International Nuclear Information System (INIS)

    Semina, O.V.; Semenets, T.N.; Zeppezauer, M.; Cebecauer, L.; Poverenny, A.M.

    1994-01-01

    Radiotherapeutic activity of histone fractions H 1 and H 2A /H 2B were studied. It was demonstrated that both fractions are able to reduce the damaging effect of ionizing radiation on spleen colony forming unit (CFU-S) population. Histone preparations stimulated colony-forming activity of bone marrow cells exposed to dose of 0.5-3.0 Gy both in the case of incubation with preparations and intravenous or intraperitoneal administration into recipients of irradiated cells. The effect of histones and accessory thymocytes on CFU-S population is compared

  10. Functional effects of cannabinoids during dopaminergic specification of human neural precursors derived from induced pluripotent stem cells.

    Science.gov (United States)

    Stanslowsky, Nancy; Jahn, Kirsten; Venneri, Anna; Naujock, Maximilian; Haase, Alexandra; Martin, Ulrich; Frieling, Helge; Wegner, Florian

    2017-09-01

    Among adolescents cannabis is one of the most widely used illicit drugs. In adolescence brain development continues, characterized by neuronal maturation and synaptic plasticity. The endocannabinoid system plays an important role during brain development by modulating neuronal function and neurogenesis. Changes in endocannabinoid signaling by Δ 9 -tetrahydrocannabinol (THC), the psychoactive component of cannabis, might therefore lead to neurobiological changes influencing brain function and behavior. We investigated the functional maturation and dopaminergic specification of human cord blood-derived induced pluripotent stem cell (hCBiPSC)-derived small molecule neural precursor cells (smNPCs) after cultivation with the endogenous cannabinoid anandamide (AEA) and the exogenous THC, both potent agonists at the cannabinoid 1 receptor (CB 1 R). Higher dosages of 10-μM AEA or THC significantly decreased functionality of neurons, indicated by reduced ion currents and synaptic activity. A lower concentration of 1-μM THC had no marked effect on neuronal and dopaminergic maturation, while 1-μM AEA significantly enhanced the frequency of synaptic activity. As there were no significant effects on DNA methylation in promotor regions of genes important for neuronal function, these cannabinoid actions seem to be mediated by another than this epigenetic mechanism. Our data suggest that there are concentration-dependent actions of cannabinoids on neuronal function in vitro indicating neurotoxic, dysfunctional effects of 10-μM AEA and THC during human neurogenesis. © 2016 Society for the Study of Addiction.

  11. Nitrogen-doped graphene: effect of graphite oxide precursors and nitrogen content on the electrochemical sensing properties.

    Science.gov (United States)

    Megawati, Monica; Chua, Chun Kiang; Sofer, Zdenek; Klímová, Kateřina; Pumera, Martin

    2017-06-21

    Graphene, produced via chemical methods, has been widely applied for electrochemical sensing due to its structural and electrochemical properties as well as its ease of production in large quantity. While nitrogen-doped graphenes are widely studied materials, the literature showing an effect of graphene oxide preparation methods on nitrogen quantity and chemical states as well as on defects and, in turn, on electrochemical sensing is non-existent. In this study, the properties of nitrogen-doped graphene materials, prepared via hydrothermal synthesis using graphite oxide produced by various classical methods using permanganate or chlorate oxidants Staudenmaier, Hummers, Hofmann and Brodie oxidation methods, were studied; the resulting nitrogen-doped graphene oxides were labeled as ST-GO, HU-GO, HO-GO and BR-GO, respectively. The electrochemical oxidation of biomolecules, such as ascorbic acid, uric acid, dopamine, nicotinamide adenine nucleotide and DNA free bases, was carried out using cyclic voltammetry and differential pulse voltammetry techniques. The nitrogen content in doped graphene oxides increased in the order ST-GO graphene followed this trend, as shown in the cyclic voltammograms. This is a very important finding that provides insight into the electrocatalytic effect of N-doped graphene. The nitrogen-doped graphene materials exhibited improved sensitivity over bare glassy carbon for ascorbic acid, uric acid and dopamine detection. These studies will enhance our understanding of the effects of graphite oxide precursors on the electrochemical sensing properties of nitrogen-doped graphene materials.

  12. The effect of inorganic precursors on disinfection byproduct formation during UV-chlorine/chloramine drinking water treatment.

    Science.gov (United States)

    Lyon, Bonnie A; Dotson, Aaron D; Linden, Karl G; Weinberg, Howard S

    2012-10-01

    Ultraviolet (UV) disinfection is being increasingly used in drinking water treatment. It is important to understand how its application to different types of water may influence finished water quality, particularly as anthropogenic activity continues to impact the quality of source waters. The objective of this study was to evaluate the effect of inorganic precursors on the formation of regulated and unregulated disinfection byproducts (DBPs) during UV irradiation of surface waters when combined with chlorination or chloramination. Samples were collected from three drinking water utilities supplied by source waters with varying organic and inorganic precursor content. The filtered samples were treated in the laboratory with a range of UV doses delivered from low pressure (LP, UV output at 253.7 nm) and medium pressure (MP, polychromatic UV output 200-400 nm) mercury lamps followed by chlorination or chloramination, in the presence and absence of additional bromide and nitrate. The regulated trihalomethanes and haloacetic acids were not affected by UV pretreatment at disinfection doses (40-186 mJ/cm²). With higher doses (1000 mJ/cm²), trihalomethane formation was increased 30-40%. While most effects on DBPs were only observed with doses much higher than typically used for UV disinfection, there were some effects on unregulated DBPs at lower doses. In nitrate-spiked samples (1-10 mg N/L), chloropicrin formation doubled and increased three- to six-fold with 40 mJ/cm² MP UV followed by chloramination and chlorination, respectively. Bromopicrin formation was increased in samples containing bromide (0.5-1 mg/L) and nitrate (1-10 mg N/L) when pretreated with LP or MP UV (30-60% with 40 mJ/cm² LP UV and four- to ten-fold increase with 40 mJ/cm² MP UV, after subsequent chlorination). The formation of cyanogen chloride doubled and increased three-fold with MP UV doses of 186 and 1000 mJ/cm², respectively, when followed by chloramination in nitrate-spiked samples but

  13. Efeito da adição de polímero precursor cerâmico na sinterização de alumina Effect of the addition of ceramic polymeric precursor on alumina sintering

    Directory of Open Access Journals (Sweden)

    A. L. E Godoy

    2010-03-01

    Full Text Available Foram estudados os efeitos da adição de polímero precursor na sinterização, microestrutura e dureza da alumina. O polímero inorgânico polifenilmetilvinilhidrogenosilsesquioxano (PPS foi utilizado como aditivo em cerâmicas de alumina sinterizadas a 1650 ºC. Os materiais sinterizados foram caracterizados por dilatometria, determinando-se a densidade aparente por picnometria de hélio, pela análise de carbono total, por difração de raios X, por microscopia eletrônica de varredura, espectrometria de energia dispersiva de raios X e por análise de indentação Vickers para determinação de dureza e tenacidade a fratura. Foram obtidas fases heterogêneas de Si2Al4O4N4 nas amostras com PPS. Dentre as amostras analisadas, a que contém 5% de PPS apresentou dureza e tenacidade à fratura superiores à da alumina pura. A preparação de compósitos cerâmicos com pequenas quantidades de polímero precursor mostrou-se um processo adequado para cerâmicas à base de alumina, sendo uma rota simples de conformação com grande potencial para a obtenção de peças com geometria complexa.The effects of the addition of precursor polymer on sintering, microstructure and hardness of alumina ceramics were studied. The linear shrinkage of cold-pressed specimens was studied by dilatometry. Polyphenylmethylvinylhidrogensilsesquioxane (PPS polymer sintering aid was used for alumina based ceramics sintered at 1650 ºC. The sintered materials were characterized by determination of apparent density by helium picnometry, by evaluation of total carbon content, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectrometry, and by Vickers indentation analysis for determining hardness and fracture toughness. Heterogeneous Si2Al4O4 phases were obtained in specimens with PPS. The specimens with 5% of PPS presented hardness and toughness greater than the obtained for pure alumina. The preparation of ceramic composites using small amounts of

  14. The effectiveness of removing precursors of chlorinated organic substances in pilot water treatment plant

    Science.gov (United States)

    Wolska, Małgorzata; Szerzyna, Sławomir; Machi, Justyna; Mołczan, Marek; Adamski, Wojciech; Wiśniewski, Jacek

    2017-11-01

    The presence of organic substances in the water intaken for consumption could be hazardous to human health due to the potential formation of disinfection by-products (TOX). The study were carried out in the pilot surface water treatment system consisting of coagulation, sedimentation, filtration, ozonation, adsorption and disinfection. Due to continuous operation of the system and interference with the parameters of the processes it was possible not only assess the effectiveness of individual water treatment processes in removing TOX, but also on factors participating on the course of unit processes.

  15. Acute Exposure to a Precursor of Advanced Glycation End Products Induces a Dual Effect on the Rat Pancreatic Islet Function

    Directory of Open Access Journals (Sweden)

    Ghada Elmhiri

    2014-01-01

    Full Text Available Aim. Chronic diseases are the leading cause of death worldwide. Advanced glycation end products, known as AGEs, are a major risk factor for diabetes onset and maintenance. Methylglyoxal (MG, a highly reactive metabolite of glucose, is a precursor for the generation of endogenous AGEs. Methods. In this current study we incubated in vitro pancreatic islets from adult rats in absence or presence of MG (10 μmol/l with different concentrations of glucose and different metabolic components (acetylcholine, epinephrine, potassium, forskolin, and leucine. Results. Different effects of MG on insulin secretion were evidenced. In basal glucose stimulation (5.6 mM, MG induced a significant (P<0.05 increase of insulin secretion. By contrast, in higher glucose concentrations (8.3 mM and 16.7 mM, MG significantly inhibited insulin secretion (P<0.05. In the presence of potassium, forskolin, and epinephrine, MG enhanced insulin secretion (P<0.05, while when it was incubated with acetylcholine and leucine, MG resulted in a decrease of insulin secretion (P<0.05. Conclusion. We suggest that MG modulates the secretion activity of beta-cell depending on its level of stimulation by other metabolic factors. These results provide insights on a dual acute effect of MG on the pancreatic cells.

  16. Molecular structures of (3-aminopropyl)trialkoxysilane on hydroxylated barium titanate nanoparticle surfaces induced by different solvents and their effect on electrical properties of barium titanate based polymer nanocomposites

    International Nuclear Information System (INIS)

    Fan, Yanyan; Wang, Guanyao; Huang, Xingyi; Bu, Jing; Sun, Xiaojin; Jiang, Pingkai

    2016-01-01

    Graphical abstract: - Highlights: • The silanization on the surface of hydroxylated barium titanate nanoparticles was introduced by using two kinds of trialkoxysilanes with different solvents (toluene and ethanol), respectively. • Solvents have more remarkable impact on the dielectric properties of the subsequent BT/PVDF nanocomposites than the types of silanes. • The solvents used for BT nanoparticle surface modification exhibit a significant effect on the breakdown strength of the nanocomposites. - Abstract: Surface modification of nanoparticles by grafting silane coupling agents has proven to be a significant approach to improve the interfacial compatibility between inorganic filler and polymer matrix. However, the impact of grafted silane molecular structure after the nanoparticle surface modification, induced by the utilized solvents and the silane alkoxy groups, on the electrical properties of the corresponding nanocomposites, has been seldom investigated. Herein, the silanization on the surface of hydroxylated barium titanate (BT-OH) nanoparticles was introduced by using two kinds of trialkoxysilane, 3-aminopropyltriethoxysilane (AMEO) and 3-aminopropyltrimethoxysilane (AMMO), with different solvents (toluene and ethanol), respectively. Solid-state 13 C, 29 Si nuclear magnetic resonance (NMR) spectroscopy and high-resolution X-ray photoelectron spectroscopy (XPS) were employed to validate the structure differences of alkoxysilane attachment to the nanoparticles. The effect of alkoxysilane structure attached to the nanoparticle surface on the dielectric properties of the BT based poly(vinylidene fluoride) (PVDF) nanocomposites were investigated. The results reveal that the solvents used for BT nanoparticle surface modification exhibit a significant effect on the breakdown strength of the nanocomposites. Nevertheless, the alkoxy groups of silane show a marginal influence on the dielectric properties of the nanocomposites. These research results provide

  17. Projections of mid-century summer air-quality for North America: effects of changes in climate and precursor emissions

    Science.gov (United States)

    Kelly, J.; Makar, P. A.; Plummer, D. A.

    2012-06-01

    Ten year simulations of North American current and future air-quality were carried out using a regional air-quality model driven by a regional climate model, in turn driven by a general circulation model. Three separate summer scenarios were performed: a scenario representing the years 1997 to 2006, and two SRES A2 climate scenarios for the years 2041 to 2050. The first future climate scenario makes use of 2002 anthropogenic precursor emissions, and the second applied emissions scaling factors derived from the IPCC Representative Concentration Pathway 6 (RCP 6) scenario to estimate emissions for 2050 from existing 2020 projections. Ten-year averages of ozone and PM2.5 at North American monitoring network stations were used to evaluate the model's current chemical climatology. The model was found to have a similar performance for ozone as when driven by an operational weather forecast model. The PM2.5 predictions had larger negative biases, likely resulting from the absence of rainwater evaporation, and from sub-regional negative biases in the surface temperature fields, in the version of the climate model used here. The differences between the two future climate simulations and the current climate simulation were used to predict the changes to air-quality that might be expected in a future warmer climate, if anthropogenic precursor emissions remain constant at their current levels, versus if the RCP 6 emissions controls were adopted. Metrics of concentration, human health, and ecosystem damage were compared for the simulations. The scenario with future climate and current anthropogenic emissions resulted in worse air-quality than for current conditions - that is, the effect of climate-change alone, all other factors being similar, would be a worsening of air-quality. These effects are spatially inhomogeneous, with the magnitude and sign of the changes varying with region. The scenario with future climate and RCP 6 emissions for 2050 resulted in an improved air

  18. Projections of mid-century summer air-quality for North America: effects of changes in climate and precursor emissions

    Directory of Open Access Journals (Sweden)

    J. Kelly

    2012-06-01

    Full Text Available Ten year simulations of North American current and future air-quality were carried out using a regional air-quality model driven by a regional climate model, in turn driven by a general circulation model. Three separate summer scenarios were performed: a scenario representing the years 1997 to 2006, and two SRES A2 climate scenarios for the years 2041 to 2050. The first future climate scenario makes use of 2002 anthropogenic precursor emissions, and the second applied emissions scaling factors derived from the IPCC Representative Concentration Pathway 6 (RCP 6 scenario to estimate emissions for 2050 from existing 2020 projections. Ten-year averages of ozone and PM2.5 at North American monitoring network stations were used to evaluate the model's current chemical climatology. The model was found to have a similar performance for ozone as when driven by an operational weather forecast model. The PM2.5 predictions had larger negative biases, likely resulting from the absence of rainwater evaporation, and from sub-regional negative biases in the surface temperature fields, in the version of the climate model used here.

    The differences between the two future climate simulations and the current climate simulation were used to predict the changes to air-quality that might be expected in a future warmer climate, if anthropogenic precursor emissions remain constant at their current levels, versus if the RCP 6 emissions controls were adopted. Metrics of concentration, human health, and ecosystem damage were compared for the simulations. The scenario with future climate and current anthropogenic emissions resulted in worse air-quality than for current conditions – that is, the effect of climate-change alone, all other factors being similar, would be a worsening of air-quality. These effects are spatially inhomogeneous, with the magnitude and sign of the changes varying with region. The scenario with future climate and RCP 6

  19. The effect of X-rays on the precursors of antibody forming cells (B cells) as measured with the in vitro limiting dilution assay

    NARCIS (Netherlands)

    Lubbe, F.H.; Hooijkaas, H.; Preesman, A.A.

    1982-01-01

    The effect of X-irradiation upon murine antibody-forming cell precursors (B cells) was established in cultures of spleen cells stimulated with the B cell mitogen lipopolysaccharide (LPS). At day 5 and 7 the numbers of IgM- and IgG2-secreting cells were determined in cultures of irradiated and

  20. Metal and Precursor Effect during 1-Heptyne Selective Hydrogenation Using an Activated Carbon as Support

    Directory of Open Access Journals (Sweden)

    Cecilia R. Lederhos

    2013-01-01

    Full Text Available Palladium, platinum, and ruthenium supported on activated carbon were used as catalysts for the selective hydrogenation of 1-heptyne, a terminal alkyne. All catalysts were characterized by temperature programmed reduction, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. TPR and XPS suggest that the metal in all catalysts is reduced after the pretreatment with H2 at 673 K. The TPR trace of the PdNRX catalyst shows that the support surface groups are greatly modified as a consequence of the use of HNO3 during the catalyst preparation. During the hydrogenation of 1-heptyne, both palladium catalysts were more active and selective than the platinum and ruthenium catalysts. The activity order of the catalysts is as follows: PdClRX > PdNRX > PtClRX ≫ RuClRX. This superior performance of PdClRX was attributed in part to the total occupancy of the d electronic levels of the Pd metal that is supposed to promote the rupture of the H2 bond during the hydrogenation reaction. The activity differences between PdClRX and PdNRX catalysts could be attributed to a better accessibility of the substrate to the active sites, as a consequence of steric and electronic effects of the superficial support groups. The order for the selectivity to 1-heptene is as follows: PdClRX = PdNRX > RuClRX > PtClRX, and it can be mainly attributed to thermodynamic effects.

  1. Metal and Precursor Effect during 1-Heptyne Selective Hydrogenation Using an Activated Carbon as Support

    Science.gov (United States)

    Lederhos, Cecilia R.; Badano, Juan M.; Carrara, Nicolas; Coloma-Pascual, Fernando; Almansa, M. Cristina; Liprandi, Domingo; Quiroga, Mónica

    2013-01-01

    Palladium, platinum, and ruthenium supported on activated carbon were used as catalysts for the selective hydrogenation of 1-heptyne, a terminal alkyne. All catalysts were characterized by temperature programmed reduction, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. TPR and XPS suggest that the metal in all catalysts is reduced after the pretreatment with H2 at 673 K. The TPR trace of the PdNRX catalyst shows that the support surface groups are greatly modified as a consequence of the use of HNO3 during the catalyst preparation. During the hydrogenation of 1-heptyne, both palladium catalysts were more active and selective than the platinum and ruthenium catalysts. The activity order of the catalysts is as follows: PdClRX > PdNRX > PtClRX ≫ RuClRX. This superior performance of PdClRX was attributed in part to the total occupancy of the d electronic levels of the Pd metal that is supposed to promote the rupture of the H2 bond during the hydrogenation reaction. The activity differences between PdClRX and PdNRX catalysts could be attributed to a better accessibility of the substrate to the active sites, as a consequence of steric and electronic effects of the superficial support groups. The order for the selectivity to 1-heptene is as follows: PdClRX = PdNRX > RuClRX > PtClRX, and it can be mainly attributed to thermodynamic effects. PMID:24348168

  2. Insight into excimer laser crystallization exploiting ellipsometry: Effect of silicon film precursor

    Energy Technology Data Exchange (ETDEWEB)

    Losurdo, Maria [Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR and INSTM sez. Bari, Via Orabona 4, 70125 Bari (Italy)], E-mail: maria.losurdo@ba.imip.cnr.it; Giangregorio, Maria M.; Sacchetti, Alberto; Capezzuto, Pio; Bruno, Giovanni [Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR and INSTM sez. Bari, Via Orabona 4, 70125 Bari (Italy); Mariucci, Luigi; Fortunato, Guglielmo [IFN-CNR, Via Cineto Romano, 42 - 00156 Rome (Italy)

    2007-07-16

    The optical diagnostic of spectroscopic ellipsometry is shown to be an effective tool to investigate the mechanism of excimer laser crystallization (ELC) of silicon thin films. A detailed spectroscopic ellipsometric investigation of the microstructures of polycrystalline Si films obtained on SiO{sub 2}/Si wafers by ELC of a-Si:H and nc-Si films deposited, respectively, by SiH{sub 4} plasma enhanced chemical vapor deposition (PECVD) and SiF{sub 4}-PECVD is presented. It is shown that ellipsometric spectra of the pseudodielectric function of polysilicon thin films allows to discern the three different ELC regimes of partial melting, super lateral growth and complete melting. Exploiting ellipsometry and atomic force microscopy, it is shown that ELC of nc-Si has very low energy density threshold of 95 mJ/cm{sup 2} for complete melting, and that re-crystallization to large grains of {approx} 2 {mu}m can be achieved by multi-shot irradiation at an energy density as low as 260 mJ/cm{sup 2} when using nc-Si when compared to 340 mJ/cm{sup 2} for the ELC of a-Si films.

  3. Sulfide precursor concentration and lead source effect on PbS thin films properties

    Energy Technology Data Exchange (ETDEWEB)

    Beddek, L.; Messaoudi, M.; Attaf, N. [Laboratoire Couche Minces et Interfaces, Université frères Mentouri Constantine, 25000, Constantine (Algeria); Aida, M.S., E-mail: aida_salah2@yahoo.fr [Laboratoire Couche Minces et Interfaces, Université frères Mentouri Constantine, 25000, Constantine (Algeria); Bougdira, J. [Université de Lorraine, Institut Jean Lamour UMR 7198, Vandoeuvre 54506 (France)

    2016-05-05

    Lead sulfide (PbS) thin films were synthesized using chemical bath deposition (CBD). Bath solutions are formed of various concentrations of thiourea, sulfide source, ranged from 0.6 to 1.2 M and two different salts as Pb source (lead acetate and lead nitrate). From the growth mechanism, we inferred that PbS is formed through the ion by ion process when using acetate lead source, while, using nitrate source yields to films growth through the complex-decomposition process. Due to the difference in the involved growth process, lead acetate produces films with larger crystallite size (from 4 to 16 nm), smooth and dense films. However, lead nitrate produces rough films with smaller crystallite size (from 1 to 4 nm). Increasing the thiourea concentration results in crystallinity improvement when using lead acetate and, oppositely, in crystallinity degradation when using lead nitrate. Due to the quantum effect caused by the small crystallite sizes, the films optical gap is varied from 0.5 to 0.9 eV. - Highlights: • PbS thin films were synthesized by chemical bath deposition. • Ion by ion is the growth process when using the acetate lead source. • Deposition process is by complex-decomposition when using nitrate source. • Lead acetate yields to dense films with larger crystallite size. • Lead nitrate produces rough films with smaller crystallite size.

  4. Effects of meteorological conditions and plant growth stage on the accumulation of carvacrol and its precursors in Thymus pulegioides.

    Science.gov (United States)

    Vaičiulytė, Vaida; Butkienė, Rita; Ložienė, Kristina

    2016-08-01

    The effects of meteorological conditions (temperature, rainfall, photosynthetically active solar radiation (PAR) and sunshine duration) and plant growth stages on the quantitative composition of a secondary metabolite - essential oil and its main compounds, in the carvacrol chemotype of Thymus pulegioides L. (Lamiaceae) cultivated in open ground were studied under the same micro-edaphoclimatic environmental conditions for six years. The essential oil was isolated by hydrodistillation, the analysis of monoterpenic phenol carvacrol and the biogenetic precursors (monoterpene hydrocarbons p-cymene and γ-terpinene) were carried out annually using GC-FID and GC-MS. In the carvacrol chemotype investigated in this study, the yield of essential oil varied from 0.72% to 0.98% (CV = 12%) at full flowering stage. Regression analysis showed a significant negative relationship between the amount of essential oil and both temperature and rainfall during T. pulegioides flowering (July) and the period from April (beginning of vegetation) to July, but a strong positive relationship with photosynthetically active solar radiation during April-July (beta = 0.658, p < 0.05). The percentage of carvacrol, p-cymene and γ-terpinene ranged between 16.88 and 29.29% (CV = 18%), 5.54-11.33% (CV = 23%) and 20.60-24.43% (CV = 6%) respectively. Regression analysis showed the significant positive relationship between the percentage of carvacrol and sunshine duration at the flowering stage (in July) (beta = 0.699, p < 0.05); while the negative relationship was established between the percentages of precursors of carvacrol and photosynthetically active solar radiation and sunshine duration. The accumulation of p-cymene, the percentage of which varied most strongly from all investigated chemical compounds, showed significant positive relationships with temperature and rainfall during the period April-July and temperature in July (beta = 0.617, beta = 0.439 and beta = 0

  5. Synergic Effect between Adsorption and Photocatalysis of Metal-Free g-C3N4 Derived from Different Precursors.

    Directory of Open Access Journals (Sweden)

    Huan-Yan Xu

    Full Text Available Graphitic carbon nitride (g-C3N4 used in this work was obtained by heating dicyandiamide and melamine, respectively, at different temperatures. The differences of g-C3N4 derived from different precursors in phase composition, functional group, surface morphology, microstructure, surface property, band gap and specific surface area were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-visible diffuse reflection spectroscopy and BET surface area analyzer, respectively. The photocatalytic discoloration of an active cationic dye, Methylene Blue (MB under visible-light irradiation indicated that g-C3N4 derived from melamine at 500°C (CN-M500 had higher adsorption capacity and better photocatalytic activity than that from dicyandiamide at 500°C (CN-D500, which was attributed to the larger surface area of CN-M500. MB discoloration ratio over CN-M500 was affected by initial MB concentration and photocatalyst dosage. After 120 min reaction time, the blue color of MB solution disappeared completely. Subsequently, based on the measurement of the surface Zeta potentials of CN-M500 at different pHs, an active anionic dye, Methyl Orange (MO was selected as the contrastive target pollutant with MB to reveal the synergic effect between adsorption and photocatalysis. Finally, the photocatalytic mechanism was discussed.

  6. Synergic Effect between Adsorption and Photocatalysis of Metal-Free g-C3N4 Derived from Different Precursors

    Science.gov (United States)

    Xu, Huan-Yan; Wu, Li-Cheng; Zhao, Hang; Jin, Li-Guo; Qi, Shu-Yan

    2015-01-01

    Graphitic carbon nitride (g-C3N4) used in this work was obtained by heating dicyandiamide and melamine, respectively, at different temperatures. The differences of g-C3N4 derived from different precursors in phase composition, functional group, surface morphology, microstructure, surface property, band gap and specific surface area were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-visible diffuse reflection spectroscopy and BET surface area analyzer, respectively. The photocatalytic discoloration of an active cationic dye, Methylene Blue (MB) under visible-light irradiation indicated that g-C3N4 derived from melamine at 500°C (CN-M500) had higher adsorption capacity and better photocatalytic activity than that from dicyandiamide at 500°C (CN-D500), which was attributed to the larger surface area of CN-M500. MB discoloration ratio over CN-M500 was affected by initial MB concentration and photocatalyst dosage. After 120 min reaction time, the blue color of MB solution disappeared completely. Subsequently, based on the measurement of the surface Zeta potentials of CN-M500 at different pHs, an active anionic dye, Methyl Orange (MO) was selected as the contrastive target pollutant with MB to reveal the synergic effect between adsorption and photocatalysis. Finally, the photocatalytic mechanism was discussed. PMID:26565712

  7. Effect of nitrogen precursors on the electrochemical performance of nitrogen-doped reduced graphene oxide towards oxygen reduction reaction

    Energy Technology Data Exchange (ETDEWEB)

    Soo, Li Ting, E-mail: nicolesoo90@gmail.com [Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 Bangi UKM, Selangor (Malaysia); Loh, Kee Shyuan, E-mail: ksloh@ukm.edu.my [Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 Bangi UKM, Selangor (Malaysia); Mohamad, Abu Bakar, E-mail: drab@ukm.edu.my [Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 Bangi UKM, Selangor (Malaysia); Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi UKM, Selangor (Malaysia); Daud, Wan Ramli Wan, E-mail: wramli@ukm.edu.my [Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 Bangi UKM, Selangor (Malaysia); Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi UKM, Selangor (Malaysia); Wong, Wai Yin, E-mail: waiyin.wwy@gmail.com [Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 Bangi UKM, Selangor (Malaysia); School of Engineering, Taylor' s University' s Lakeside Campus, No. 1, Jalan Taylor' s, 46500 Subang Jaya, Selangor (Malaysia)

    2016-08-25

    A series of nitrogen-doped reduced graphene oxides (NGs) with different ratios are synthesized by thermal annealing of graphene oxide with melamine or urea. The total nitrogen content in NG is high, with values of up to 5.88 at.%. The NG samples prepared by melamine exhibited thin transparent graphene sheets structure, with consist of higher nitrogen doping level and quaternary N content compared to those NG samples prepared from urea. Electrochemical characterizations show that NG is a promising metal-free electrocatalyst for an oxygen reduction reaction (ORR). Incorporation of nitrogen atoms into graphene basal plane can enhances its electrocatalytic activity toward ORR in alkaline media. The onset potential and mean number of electron transfers on NG 1 are −0.10 V and 3.80 respectively, which is higher than that of reduced graphene oxide (−0.15 V, 3.52). This study suggests that quaternary-N of the NG samples is the active site which determines the ORR activity Moreover, the NG samples with the transparent layer of graphene-like structure have better ORR performances than that of bulk graphite-like NG samples. - Highlights: • Synthesis of nitrogen-doped graphene (NG) via thermal annealing. • The effects of the nitrogen precursors on the synthesized NG are discussed. • Electrochemical performances of the NG are correlated to N doping and EASA. • Graphitic-N is proposed to be the active site for ORR.

  8. Efecto de la naturaleza del precursor sobre las caracteristicas de las nanoparticulas de SnO2 sintetizadas Effect of the precursor's nature on characteristics of synthesized SnO2 nanoparticles

    Directory of Open Access Journals (Sweden)

    Carlos E. Ararat-Ibarguen

    2007-01-01

    Full Text Available Tin oxide (SnO2 is widely used in industry as raw material for electronic devices, plating of different types of materials, for dyes and pigments, for electroplating, heterogeneous catalysis, etc. In this work SnO2 was obtained by a controlled precipitation method with special attention to the effects the tin precursor has on the microstructure of the final product. The most appropriate pH for obtaining SnO2 with the rutile structure as the main phase is 6.25 for SnCl2 and 6.40 for SnSO4. After heat treatment at 600 °C, particles of nanometric order (~10 - 30 nm approx were obtained. The characterization of the solid phase was made by X-ray diffraction (XRD, thermal analysis (DTA/TG, transmission electron microscopy (TEM and Fourier transformed infrared spectroscopy (FTIR.

  9. Effect of the calcining temperature on the porosity of the titanium dioxide powders obtained by Polymeric Precursor Method; Efeito da temperatura de calcinacao na porosidade de pos de dioxido de titanio obtidos pelo Metodo dos Precursores Polimericos

    Energy Technology Data Exchange (ETDEWEB)

    Silva, D.W.; Granado, S.R.; Ciola, R.A.; Cavalheiro, A.A., E-mail: douglas_levis@hotmail.com [Universidade Estadual de Mato Grosso do Sul (CPTREN/UEMS), Navirai, MS (Brazil). Centro de Pesquisas Tecnologicas em Recursos Naturais

    2011-07-01

    Ceramics materials obtained by Polymeric Precursor Method exhibit mechanisms of the pore formation and elimination dependents on the decomposition kinetics of the residual organic matter of the polyester. The mechanism of pore elimination seems to occur by disrupting of the wall among the pores because it leads to the consequent pore coalescence and increasing in pore volume, which posses higher pore diameters. In this case, it was observed that the porosity decreasing occurs by pore wall moving after that the residual organic matter is eliminated from the pore inside. The pore diameter associated to the highest volume desorption occurred for the material obtained after calcining at 450°C is approximately 1,7 nm, what seems to be related to the amorphous carbon accumulated inside the pores, once that the pore volume decreases more effectively for the material obtained by calcining at 550°C, making the maximum volume situates at 2,0 nm. (author)

  10. Synthesis, Structure, Characterization, and Decomposition of Nickel Dithiocarbamates: Effect of Precursor Structure and Processing Conditions on Solid-State Products

    Science.gov (United States)

    Hepp, Aloysius F.; Kulis, Michael J.; McNatt, Jeremiah S.; Duffy, Norman V.; Hoops, Michael D.; Gorse, Elizabeth; Fanwick, Philip E.; Masnovi, John; Cowen, Jonathan E.; Dominey, Raymond N.

    2016-01-01

    Single-crystal X-ray structures of four nickel dithiocarbamate complexes, the homoleptic mixed-organic bis-dithiocarbamates Ni[S2CN(isopropyl)(benzyl)]2, Ni[S2CN(ethyl)(n-butyl)]2, and Ni[S2CN(phenyl)(benzyl)]2, as well as the heteroleptic mixed-ligand complex NiCl[P(phenyl)3][(S2CN(phenyl)(benzyl)], were determined. Synthetic, spectroscopic, structural, thermal, and sulfide materials studies are discussed in light of prior literature. The spectroscopic results are routine. A slightly distorted square-planar nickel coordination environment was observed for all four complexes. The organic residues adopt conformations to minimize steric interactions. Steric effects also may determine puckering, if any, about the nickel and nitrogen atoms, both of which are planar or nearly so. A trans-influence affects the Ni-S bond distances. Nitrogen atoms interact with the CS2 carbons with a bond order of about 1.5, and the other substituents on nitrogen display transoid conformations. There are no strong intermolecular interactions, consistent with prior observations of the volatility of nickel dithiocarbamate complexes. Thermogravimetric analysis of the homoleptic species under inert atmosphere is consistent with production of 1:1 nickel sulfide phases. Thermolysis of nickel dithiocarbamates under flowing nitrogen produced hexagonal or -NiS as the major phase; thermolysis under flowing forming gas produced millerite (-NiS) at 300 C, godlevskite (Ni9S8) at 325 and 350 C, and heazlewoodite (Ni3S2) at 400 and 450 C. Failure to exclude oxygen results in production of nickel oxide. Nickel sulfide phases produced seem to be primarily influenced by processing conditions, in agreement with prior literature. Nickel dithiocarbamate complexes demonstrate significant promise to serve as single-source precursors to nickel sulfides, a quite interesting family of materials with numerous potential applications.

  11. Thermo-radiosensitivity of the granulocyte and macrophage precursor cells of mice. I I . - X- irradiation effects and influence of hyperthermia on the radiosensitivity; Termo-radiosensibilidad del precursor hematopoyetico que origina las series granulocitica y macrofaga de raton. II. - Efectos producidos por la radiacion X e influencia de la hipertermia sobre la radiosensibilidad celular

    Energy Technology Data Exchange (ETDEWEB)

    Bueren, J. A.; Nieto, M.

    1983-07-01

    The effects of the X-irradiation on the viability of the granulocyte-macrophage precursors, has been determined by means of the agar diffusion chamber culture technique. The results show the high radiosensitivity of these cells, with survival parameter similar to those previously reported in the literature about different granulocyte-macrophage precursors. When a hyperthermic treatment is performed prior to the X-irradiation, a radiosensitization phenomenon is observed due to the synergism existent between hyperthermia and X rays on the lethality of the precursors. (Authors) 37 refs.

  12. Thermo-radiosensitivity of the granulocyte and macrophage precursor cells of mice. I.-Development of the in vivo culture and effects induced by the hyperthermia; Termo-radiosensibilidad del precursor hematopoyetico que origina las series granulocitica y macrofaga de raton. I.- Desarrollo del cultivo in vivo y efectos producidos por la hipertermia

    Energy Technology Data Exchange (ETDEWEB)

    Bueren, J. A.; Nieto, M.

    1983-07-01

    The present report shows the agar diffusion chamber technique for culturing granulocyte- macrophage precursor cells, obtained from mice bone marrow. Diffusion chambers containing the bone marrow suspension are implanted intraperitoneally Into mice and constitute a compartment which avoids the migration of cells, but allows the transit of the mouse biological fluxes, necessary for the cellular proliferation. By means of this technique, we studied the lethal effects of the hyperthermia on the precursors and their capacity to repair sublethal damage. (Author) 129 refs.

  13. Effects of precursor and sulfation on OMS-2 catalyst for oxidation of ethanol and acetaldehyde at low temperatures.

    Science.gov (United States)

    Wang, Renhu; Li, Junhua

    2010-06-01

    Volatile organic compounds (VOCs) emitted from many industrial processes and transportation activities are major organic pollutants in the atmosphere and toxic to human health. Octahedral molecular sieve (OMS-2) catalysts with different precursors and sulfate-acidified OMS-2 catalysts were synthesized using refluxing methods. The catalysts were investigated on complete oxidation of ethanol and acetaldehyde, and both demonstrated good reactivity. However, acidification resulted in a decrease in activity. OMS-2 catalyst using MnSO(4) as precursor exhibited the best catalytic performance and, thus, was selected for catalyst deactivation by sulfur dioxide. The results of this study suggested that the Mn-O bond of OMS-2 catalysts was the main determinant of the catalytic activity toward oxygenated VOC oxidation and weaker acid sites benefited higher acetaldehyde selectivity. Catalyst deactivation resulted from a strong but slow chemical interaction between the Mn-O bond and sulfur dioxide, probably forming manganese sulfate.

  14. The effect of glia-glia interactions on oligodendrocyte precursor cell biology during development and in demyelinating diseases

    OpenAIRE

    Clemente, Diego; Ortega, M.C.; Melero-Jerez, Carolina; Castro Soubriet, Fernando de

    2013-01-01

    Oligodendrocyte precursor cells (OPCs) originate in specific areas of the developing central nervous system (CNS). Once generated, they migrate towards their destinations where they differentiate into mature oligodendrocytes. In the adult, 5–8% of all cells in the CNS are OPCs, cells that retain the capacity to proliferate, migrate, and differentiate into oligodendrocytes. Indeed, these endogenous OPCs react to damage in demyelinating diseases, like multiple sclerosis (MS), representing a key...

  15. Effect of Precursor Synthesis on Catalytic Activity of Co3O4 in N2O Decomposition.

    Czech Academy of Sciences Publication Activity Database

    Chromčáková, Ž.; Obalová, L.; Kovanda, F.; Legut, D.; Titov, A.; Ritz, M.; Fridrichová, D.; Michalik, S.; Kustrowski, P.; Jirátová, Květa

    2015-01-01

    Roč. 257, Part 1 (2015), s. 18-25 ISSN 0920-5861. [AWPAC2014 - International Symposium on Air & Water Pollution Abatement Catalysis. Krakow, 01.09.2014-05.09.2014] R&D Projects: GA ČR GA14-13750S Institutional support: RVO:67985858 Keywords : cobalt spinel * Co3O4 * N2O decomposition * precursor synthesis Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 4.312, year: 2015

  16. Effects of the ratio of Cu/Co and metal precursors on the catalytic activity over Cu-Co/Al2O3 prepared using the polyol process

    International Nuclear Information System (INIS)

    Lu Chiyuan; Tseng, H.-H.; Wey Mingyen; Liu Lingyi; Chuang, K.-H.

    2009-01-01

    Cu-Co bimetallic catalysts were prepared using a simple polyol process. The effects of various metal precursors (nitrate, acetate, and chloride) and Cu/Co ratios on the activities of the catalysts were evaluated for toluene oxidation and NO reduction. The results indicated that the use of the metal precursor Cu-Co acetate in preparing the bimetallic catalysts resulted in good metal dispersion and high catalytic activity. When the atomic Cu/Co ratio was 0.21 in the Al 2 O 3 -supported catalyst, the dispersion of active sites was promoted by the Cu, and the catalytic activity was stable over the reaction time. CuO and Cu 0 species and large particle sizes (20 nm) formed when the Co loading weight in the catalyst increased, and conversion decreased. When the reaction temperature was 300 deg. C, NO and toluene were able to be simultaneously removed with high conversion rates (83% and 98%)

  17. Acrylate-endcapped polymer precursors: effect of chemical composition on the healing efficiency of active concrete cracks

    Science.gov (United States)

    Araújo, Maria; Van Tittelboom, Kim; Dubruel, Peter; Van Vlierberghe, Sandra; De Belie, Nele

    2017-05-01

    The repair of cracks in concrete is an unavoidable practice since these cracks endanger the durability of the structure. Inspired by nature, the self-healing concept has been widely investigated in concrete as a promising solution to solve the limitations of manual repair. This self-healing functionality may be realized by the incorporation of encapsulated healing agents in concrete. Depending on the nature of the cracks, different healing agents can be used. For structures subjected to repeated loads, elastic materials should be considered to cope with the crack opening and closing movement. In this study, various acrylate-endcapped polymer precursors were investigated for their suitability to heal active cracks. The strain capacity of the polymers was assessed by means of visual observation together with water flow tests after widening of the healed cracks in a stepwise manner. A strain of at least 50% could be sustained by epoxy- and siloxane-based healing agents. For polyester- and urethane/poly(propylene glycol)-based precursors, failure occurred at 50% elongation due to detachment of the polymer from the crack walls. However, for urethane/poly(propylene glycol)-based healing agent, debonding was limited to some local spots. The resistance of the polymerized healing agents against degradation in the strong alkaline environment characteristic for concrete has also been evaluated, with the urethane/poly(propylene glycol)-based precursor showing the best performance to withstand degradation.

  18. Surface-Induced Hybridization between Graphene and Titanium

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Allen L. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States).; Koch, Roland J. [Technische Universitat, Chemnitz (Germany); Ong, Mitchell T. [Stanford Univ., CA (United States); Fang, Wenjing [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States); Hofmann, Mario [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States); Kim, Ki Kang [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States).; Seyller, Thomas [Technische Universitat, Chemnitz (Germany); Dresselhaus, Mildred S. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States); Reed, Evan J. [Stanford Univ., CA (United States); Kong, Jing [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States); Palacios, Tomás [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States)

    2014-08-26

    Carbon-based materials such as graphene sheets and carbon nanotubes have inspired a broad range of applications ranging from high-speed flexible electronics all the way to ultrastrong membranes. However, many of these applications are limited by the complex interactions between carbon-based materials and metals. In this work, we experimentally investigate the structural interactions between graphene and transition metals such as palladium (Pd) and titanium (Ti), which have been confirmed by density functional simulations. We find that the adsorption of titanium on graphene is more energetically favorable than in the case of most metals, and density functional theory shows that a surface induced p-d hybridization occurs between atomic carbon and titanium orbitals. This strong affinity between the two materials results in a short-range ordered crystalline deposition on top of graphene as well as chemical modifications to graphene as seen by Raman and X-ray photoemission spectroscopy (XPS). This induced hybridization is interface-specific and has major consequences for contacting graphene nanoelectronic devices as well as applications toward metal-induced chemical functionalization of graphene.

  19. Precursors and BRST symmetry

    Science.gov (United States)

    de Boer, Jan; Freivogel, Ben; Kabir, Laurens; Lokhande, Sagar F.

    2017-07-01

    In the AdS/CFT correspondence, bulk information appears to be encoded in the CFT in a redundant way. A local bulk field corresponds to many different non-local CFT operators (precursors). We recast this ambiguity in the language of BRST symmetry, and propose that in the large N limit, the difference between two precursors is a BRST exact and ghost-free term. This definition of precursor ambiguities has the advantage that it generalizes to any gauge theory. Using the BRST formalism and working in a simple model with global symmetries, we re-derive a precursor ambiguity appearing in earlier work. Finally, we show within this model that the obtained ambiguity has the right number of parameters to explain the freedom to localize precursors within different spatial regions of the boundary order by order in the large N expansion.

  20. Natural variations of precursors in pig meat affect the yield of heterocyclic amines--effects of RN genotype, feeding regime, and sex.

    Science.gov (United States)

    Olsson, Viktoria; Solyakov, Alexey; Skog, Kerstin; Lundström, Kerstin; Jägerstad, Margaretha

    2002-05-08

    Pig meat shows natural variations in the concentrations of precursors of heterocyclic amines (HCAs), which may affect formation of HCAs in cooked pig meat. To study this, 26 pigs with an inherent genetic variation (carriers and noncarriers of the RN(-) allele) were subjected to different feeding regimes (conventional feed compared with feed composed according to organic standards). In addition, the effect of sex (castrated males or females) was considered when assessing chemical and technological meat quality parameters. Concentrations of precursors of HCAs, i.e., creatine, residual glycogen, dipeptides, and free amino acids, were analyzed in the raw meat, and the levels of some HCAs (4,8-DiMeIQx, MeIQx, PhIP, harman, and norharman) were then determined in fried meat patties prepared from these pigs. The RN genotype most affected technological meat quality parameters and the level of precursors of HCAs, especially the level of residual glycogen, where carriers of the RN(-) allele showed levels four times as high as those of noncarriers (75.3 +/- 2.6 compared with 17.2 +/- 2.4 micromol/g meat, least-squares means +/- SE). The increased level of residual glycogen resulted in about 50% lower amounts of total mutagenic HCAs in cooked meat compared with cooked meat from normal pigs. Fried meat from carriers of the RN(-) allele obtained darker crust color than meat from noncarriers. Feeding regime and sex did not significantly affect the chemical composition of the meat or the formation of HCAs.

  1. Effects of precursor concentration and annealing temperature on CH3NH3PbI3 film crystallization and photovoltaic performance

    Science.gov (United States)

    Zheng, Yan-Zhen; Lai, Xue-Sen; Luo, Yi; Zhao, Er-Fei; Meng, Fan-Li; Zhang, Xiang-Feng; Tao, Xia

    2017-08-01

    The ability to prepare homogeneous and highly crystalline planar perovskite films via the precise manipulation of a one-step solution-based crystallization process is still a key issue that hinders improvements to the ultimate photoelectric conversion efficiency (PCE) of devices. In this study, we prepared a series of planar CH3NH3PbI3 films using a chlorobenzene-assisted fast perovskite crystallization process with various precursor concentrations ranging from 30 to 50 wt% and subsequent annealing at 50-90 °C in order to investigate the effects of the precursor concentration and annealing temperature on crystallization and the photovoltaic performance. By precisely controlling the precursor concentration and annealing temperature, we obtained a homogeneous and highly crystalline planar perovskite film with high coverage under the optimized conditions (ca. 40 wt% and 70 °C), which led to sufficient light absorption and inhibited charge recombination, thereby yielding an enhanced PCE of 16.21%. Furthermore, the unsealed cell still retained a PCE of 10.98% after ambient air exposure for a period of 408 h.

  2. A co-culture model of the hippocampal neurogenic niche reveals differential effects of astrocytes, endothelial cells and pericytes on proliferation and differentiation of adult murine precursor cells

    Directory of Open Access Journals (Sweden)

    Fanny Ehret

    2015-11-01

    Full Text Available The niche concept of stem cell biology proposes a functional unit between the precursor cells and their local microenvironment, to which several cell types might contribute by cell–cell contacts, extracellular matrix, and humoral factors. We here established three co-culture models (with cell types separated by membrane for both adherent monolayers and neurospheres to address the potential influence of different niche cell types in the neurogenic zone of the adult hippocampus of mice. Astrocytes and endothelial cells enhanced precursor cell proliferation and neurosphere formation. Endothelial factors also led to a prolonged increase in proliferation after growth factor withdrawal, which otherwise induces differentiation. All niche cell types enhanced cell survival in monolayer cultures, endothelial cells also stimulated neuronal differentiation. A parallel trend elicited by astrocytes did not reach conventional statistical significance. Pericytes had variable effects here. We did not observe changes in differentiation in neurosphere co-cultures. In summary, our data indicate that in precursor cell culture protocols survival could be improved by adding as yet unknown factors physiologically contributed by astrocytes and endothelial cells. Our findings also underscore the complexity of the niche and the differential impact of factors from the different sources on distinct aspects of neuronal development. With the help of the models presented here, identification of these factors and their specific biological activity can now be initiated.

  3. Effect of Precursors on Key Opto-electrical Properties of Successive Ion Layer Adsorption and Reaction-Prepared Al:ZnO Thin Films

    Science.gov (United States)

    Kumar, K. Deva Arun; Valanarasu, S.; Ganesh, V.; Shkir, Mohd.; Kathalingam, A.; AlFaify, S.

    2018-02-01

    Aluminum-doped zinc oxide (Al:ZnO) thin films were deposited on glass substrates by successive ion layer adsorption and reaction (SILAR) method using different precursors. This inexpensive SILAR method involves dipping of substrate sequentially in zinc solution, de-ionized water and ethylene glycol in multiple cycles. Prepared films were investigated by x-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM), optical absorption, photoluminescence (PL), Raman spectroscopy and electrical studies. XRD study confirmed incorporation of aluminum in ZnO lattice with a polycrystalline hexagonal wurtzite structure of the films. The crystallite size determined by the Scherrer equation showed an increase from 28 nm to 35 nm for samples S1 to S4, respectively. SEM study showed smooth morphology with homogeneous distribution of particles. From the AFM images, the surface roughness was found to change according to precursors. For the optical analysis, the zinc chloride precursor showed high optical transmittance of about 90% in the visible range with a band gap value 3.15 eV. The room-temperature PL spectra exhibited a stronger violet emission peak at 420 nm for all the prepared samples. The Raman spectra showed a peak around 435 cm-1 which could be assigned to non-polar optical phonons (E2-high) mode AZO films of a ZnO wurtzite structure. Hall effect measurements showed n-type conductivity with low resistivity ( ρ) and high carrier concentrations ( n) of 2.39 × 10-3 Ω-cm and 8.96 × 1020 cm-3, respectively, for the film deposited using zinc chloride as precursor. The above properties make the prepared AZO film to be regarded as a very promising electrode material for fabrication of optoelectronic devices.

  4. Fate of NDMA precursors through an MBR-NF pilot plant for urban wastewater reclamation and the effect of changing aeration conditions.

    Science.gov (United States)

    Mamo, Julian; Insa, Sara; Monclús, Hèctor; Rodríguez-Roda, Ignasi; Comas, Joaquim; Barceló, Damià; Farré, Maria José

    2016-10-01

    The removal of N-nitrosodimethylamine (NDMA) formation potential through a membrane bioreactor (MBR) coupled to a nanofiltration (NF) pilot plant that treats urban wastewater is investigated. The results are compared to the fate of the individual NDMA precursors detected: azithromycin, citalopram, erythromycin, clarithromycin, ranitidine, venlafaxine and its metabolite o-desmethylvenlafaxine. Specifically, the effect of dissolved oxygen in the aerobic chamber of the MBR pilot plant on the removal of NDMA formation potential (FP) and individual precursors is studied. During normal aerobic operation, implying a fully nitrifying system, the MBR was able to reduce NDMA precursors above 94%, however this removal percentage was reduced to values as low as 72% when changing the conditions to minimize nitrification. Removal decreased also for azithromycin (68-59%), citalopram (31-17%), venlafaxine (35-15%) and erythromycin (61-16%) on average during nitrifying versus non-nitrifying conditions. The removal of clarithromycin, o-desmethylvenlafaxine and ranitidine could not be correlated with the nitrification inhibition, as it varied greatly during the experiment time. The MBR pilot plant is coupled to a nanofiltration (NF) system and the results on the rejection of both, NDMA FP and individual precursors, through this system was above 90%. Finally, results obtained for the MBR pilot plant are compared to the percentage of removal by a conventional full scale biological wastewater treatment plant (WWTP) fed with the same influent. During aerobic operation, the removal of NDMA FP by the MBR pilot plant was similar to the full scale WWTP. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. The effect of magnetic nanoparticles on neuronal differentiation of induced pluripotent stem cell-derived neural precursors

    Czech Academy of Sciences Publication Activity Database

    Jiráková, Klára; Šeneklová, Monika; Jirák, D.; Turnovcová, Karolína; Vosmanská, M.; Babič, Michal; Horák, Daniel; Veverka, Pavel; Jendelová, Pavla

    2016-01-01

    Roč. 11, č. 2016 (2016), s. 6267-6281 E-ISSN 1178-2013 R&D Projects: GA MŠk(CZ) LQ1604; GA MŠk(CZ) ED1.1.00/02.0109; GA MŠk(CZ) 7F14057 Institutional support: RVO:68378041 ; RVO:61389013 ; RVO:68378271 Keywords : neural precursors * magnetic resonance imaging * cell differentiation Subject RIV: FH - Neurology; EB - Genetics ; Molecular Biology (FGU-C); CD - Macromolecular Chemistry (UMCH-V) Impact factor: 4.300, year: 2016

  6. Effect of Au Precursor and Support on the Catalytic Activity of the Nano-Au-Catalysts for Propane Complete Oxidation

    Directory of Open Access Journals (Sweden)

    Arshid M. Ali

    2015-01-01

    Full Text Available Catalytic activity of nano-Au-catalyst(s for the complete propane oxidation was investigated. The results showed that the nature of both Au precursor and support strongly influences catalytic activity of the Au-catalyst(s for the propane oxidation. Oxidation state, size, and dispersion of Au nanoparticles in the Au-catalysts, surface area, crystallinity, phase structure, and redox property of the support are the key aspects for the complete propane oxidation. Among the studied Au-catalysts, the AuHAuCl4-Ce catalyst is found to be the most active catalyst.

  7. Beneficial effect of human induced pluripotent stem cell-derived neural precursors in spinal cord injury repair

    Czech Academy of Sciences Publication Activity Database

    Romanyuk, Nataliya; Amemori, Takashi; Turnovcová, Karolína; Procházka, Pavel; Onteniente, B.; Syková, Eva; Jendelová, Pavla

    2015-01-01

    Roč. 24, č. 9 (2015), s. 1781-1797 ISSN 0963-6897 R&D Projects: GA MŠk LH12024; GA ČR(CZ) GA13-00939S; GA ČR(CZ) GBP304/12/G069; GA MŠk(CZ) ED1.1.00/02.0109; GA MŠk(CZ) LO1309 Institutional support: RVO:68378041 Keywords : human induced pluripotent stem cells * neural precursors * spinal cord injury Subject RIV: FH - Neurology Impact factor: 3.427, year: 2015

  8. Earthquakes: hydrogeochemical precursors

    Science.gov (United States)

    Ingebritsen, Steven E.; Manga, Michael

    2014-01-01

    Earthquake prediction is a long-sought goal. Changes in groundwater chemistry before earthquakes in Iceland highlight a potential hydrogeochemical precursor, but such signals must be evaluated in the context of long-term, multiparametric data sets.

  9. Surface-induced charge at the Ge (001) surface and its interaction with self-interstitials

    Energy Technology Data Exchange (ETDEWEB)

    Kamiyama, Eiji; Sueoka, Koji [Department of Communication Engineering, Okayama Prefectural University, 111 Kuboki, Soja-shi, Okayama-ken 719-1197 (Japan); Vanhellemont, Jan [Department of Solid State Sciences, Ghent University, B-9000 Gent (Belgium)

    2014-02-21

    The Ge (001) surface with dimer structure, is negatively charged while into the bulk, positive charges are observed even deeper than the fifteenth layer from the surface. This is different from the Si case. This charge distribution can lead to the repulsion of positively charged self-interstitials by the positively charged near surface layer in an implantation or irradiation process. Self-interstitial reflection by Ge surfaces had been proposed to explain the results of diffusion experiments during irradiation whereby positively charged self-interstitials are generated by collisions of highly energetic particles with Ge atoms. We investigated different Ge (001) surface comparing an as-cleaved surface with dangling bonds to a surface with dimer structure, and to a surface terminated by hydrogen atoms. The effect of these different surface terminations on the surface-induced charges in the near surface bulk were calculated by ab initio techniques.

  10. Amphibian tachykinin precursor.

    Science.gov (United States)

    Li, Jianxu; Liu, Tongguang; Xu, Xueqing; Wang, Xu; Wu, Min; Yang, Hailong; Lai, Ren

    2006-12-01

    The precursor of amphibian tachykinin has not been found although more than 30 tachykinins have been isolated from amphibians since 1964. In this report, two tachykinin-like peptides are identified from the skin secretions of the frog, Odorrana grahami. Their amino acid sequences are DDTEDLANKFIGLM-NH(2) (named tachykinin OG1) and DDASDRAKKFYGLM-NH(2) that is the same with ranamargarin found in Rana margaretae, respectively, with a conserved FXGLM-NH(2) C-terminal consensus motif. By cDNA cloning, their precursors were screened from the skin cDNA library of O. grahami. The precursors are composed of 61 amino acid (aa) residues including a signal peptide followed by an acidic spacer peptide and one copy of mature tachykinin-like peptide. Their overall structure is different from structures of other tachykinin precursors such as human protachykinin 1 precursor containing 143 aa including one copy of substance P (SP) and neurokinin A (NKA), and ascidian tachykinin 1 precursor containing 164 aa including two copies of tachykinin-like peptides. The current results demonstrate that the biosynthesis mode of tachykinins in amphibians is different from other animals.

  11. The interrelationships of mathematical precursors in kindergarten.

    Science.gov (United States)

    Cirino, Paul T

    2011-04-01

    This study evaluated the interrelations among cognitive precursors across quantitative, linguistic, and spatial attention domains that have been implicated for math achievement in young children. The dimensionality of the quantity precursors was evaluated in 286 kindergarteners via latent variable techniques, and the contribution of precursors from each domain was established for small sums addition. Results showed a five-factor structure for the quantity precursors, with the major distinction being between nonsymbolic and symbolic tasks. The overall model demonstrated good fit and strong predictive power (R(2)=55%) for addition number combinations. Linguistic and spatial attention domains showed indirect relationships with outcomes, with their effects mediated by symbolic quantity measures. These results have implications for the measurement of mathematical precursors and yield promise for predicting future math performance. Copyright © 2010 Elsevier Inc. All rights reserved.

  12. Synthesis and characterization of CdS quantum dots stabilized with poly(vinyl alcohol): effect of molar fraction of precursors

    International Nuclear Information System (INIS)

    Ramanery, Fabio P.; Mansur, Alexandra A.P.; Mansur, Herman S.; Gonzalez, Juan C.

    2011-01-01

    Semiconductor nanoparticles (quantum dots) with size lower than Bohr radius present quantum confinement effect, and properties dependent on particle diameter. The use of these nanoparticles for biological applications is highly promising, however this kind of use requires biocompatible systems. In this sense, the choice of poly(vinyl alcohol), PVA, as stabilizing agent has been investigated. The main goal of this work was synthesize and characterize CdS nanoparticles using PVA as capping agent varying the molar ratio of cadmium and sulfur precursors. The results revealed that absorption and emission properties, as well as nanoparticle size, were function of Cd/S ratio. (author)

  13. A structure-effect study of the induction by polyamines of the transport in vitro of the precursor of ornithine transcarbamylase.

    OpenAIRE

    Marcote, M J; Corella, D; González-Bosch, C; Hernández-Yago, J

    1994-01-01

    Polyamines induce the transport in vitro of the precursor of ornithine transcarbamylase (pOTC) into isolated rat liver mitochondria by facilitating its functional binding to these organelles. Comparative studies of the effect on the in vitro transport of pOTC of polyamine derivatives and related compounds have allowed us to establish that: (i) at least two protonated amino groups per molecule are necessary to induce the pOTC transport; (ii) a distance of three -CH2- groups between the amino g...

  14. The effect of platinum precursor concentrations on chlorine sensing characteristics of platinum nanoparticles-loaded single walled carbon nanotubes

    Science.gov (United States)

    Choi, Sun-Woo; Byun, Young Tae

    2018-03-01

    The correlation between platinum (Pt) functionalization and chlorine (Cl2) sensing capability in single-walled carbon nanotubes (SWCNTs) was investigated. Utilizing a photoreduction technique via ultraviolet (UV) irradiation, the Pt nanoparticles (NPs) with various diameters of 7-80 nm, which were controlled by Pt precursor concentrations, were successfully functionalized on the sidewalls of SWCNTs. The discrete Pt NP-loaded SWCNTs exhibited significantly enhanced response value (-(ΔR/R0) × 100 = 33.8%) for 1 ppm Cl2 at room temperature (25 °C) compared with that (no response) of pure SWCNTs. On the other hand, in case of continuous Pt NP-loaded SWCNTs, Cl2 sensing capabilities were significantly degraded. The Cl2 sensing capabilities of fabricated sensors tended to correlate with geometric configurations of the catalytic Pt NPs on the sidewalls of SWCNTs, due to differences in the electron pathway.

  15. Effects of Amyloid Precursor Protein 17 Peptide on the Protection of Diabetic Encephalopathy and Improvement of Glycol Metabolism in the Diabetic Rat

    Directory of Open Access Journals (Sweden)

    Heng Meng

    2013-01-01

    Full Text Available Researchers have proposed that amyloid precursor protein 17 peptide (APP17 peptide, an active fragment of amyloid precursor protein (APP in the nervous system, has therapeutic effects on neurodegeneration. Diabetic encephalopathy (DE is a neurological disease caused by diabetes. Here we use multiple experimental approaches to investigate the effect of APP17 peptide on changes in learning behavior and glycol metabolism in rats. It was found that rats with DE treated by APP17 peptide showed reversed behavioral alternation. The [18F]-FDG-PET images and other results all showed that the APP17 peptide could promote glucose metabolism in the brain of the DE rat model. Meanwhile, the insulin signaling was markedly increased as shown by increased phosphorylation of Akt and enhanced GLUT4 activation. Compared with the DE group, the activities of SOD, GSH-Px, and CAT in the rat hippocampal gyrus were increased, while MDA decreased markedly in the DE + APP17 peptide group. No amyloid plaques in the cortex and the hippocampus were detected in either group, indicating that the experimental animals in the current study were not suffering from Alzheimer’s disease. These results indicate that APP17 peptide could be used to treat DE effectively.

  16. Heat-up synthesis of Ag–In–S and Ag–In–S/ZnS nanocrystals: Effect of indium precursors on their optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Siqi [Department of Electrical and Biomedical Engineering, University of Nevada Reno, NV (United States); Biomedical Engineering Program, University of Nevada Reno, NV (United States); Ahmadiantehrani, Mojtaba [Department of Chemical and Materials Engineering, University of Nevada Reno, NV (United States); Zhao, Jialong [Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Jilin (China); Zhu, Shaihong [Xiangya Third Hospital of Central South University, Changsha (China); Mamalis, Athanasios G. [National Center Scientific Research “Demokritos”, Athens (Greece); Zhu, Xiaoshan, E-mail: xzhu@unr.edu [Department of Electrical and Biomedical Engineering, University of Nevada Reno, NV (United States); Biomedical Engineering Program, University of Nevada Reno, NV (United States)

    2016-04-25

    Cadmium-free I–III–VI nanocrystals (NCs) have recently attracted much research interests due to their excellent optical properties and low toxicity. In this work, with a simple heat-up synthetic system to prepare high quality Ag–In–S (AIS) NCs and their core/shell structures (AIS/ZnS NCs), we investigated the effect of different indium precursors (indium acetate and indium chloride) on NC optical properties. The measurements on photoluminescence spectra of AIS NCs show that the photoluminescence peak-wavelength of AIS NCs using indium acetate is in the range from 596 to 604 nm, and that of AIS NCs using indium chloride is from 641 to 660 nm. AIS and AIS/ZnS NCs using indium acetate present around 15% and 40% QYs, and both AIS and AIS/ZnS NCs using indium chloride present around 31% QYs. The photoluminescence decay study indicates that the lifetime parameters of AIS and AIS/ZnS using indium chloride are 2–4 times larger than those of AIS and AIS/ZnS NCs using indium acetate. Moreover, AIS NCs using indium chloride have a slower photobleaching dynamics than AIS NCs using indium acetate, and ZnS shell coating on both types of AIS NCs significantly enhances their photostability against UV exposure. We believe that the unique optical properties of AIS and AIS/ZnS NCs will open an avenue for these materials to be employed in broad electronic or biomedical applications. - Highlights: • High quality of AIS and AIS/ZnS NCs were prepared by heat-up. • Different indium precursors in AIS synthesis can impact AIS optical properties. • The impacted optical properties include emission colors, brightness and life time. • The reason why different indium precursors impact optical properties was explored. • The prepared NCs may have broad electronic and biomedical applications.

  17. The effect of mixing methods and polymer infiltration and pyrolysis (PIP) cycles on the densification of silicon carbide inert matrix fuel through a polymer precursor route

    International Nuclear Information System (INIS)

    Shih Chunghao; Tulenko, J.S.; Baney, R.H.

    2011-01-01

    Highlights: ► A pre-ceramic polymer precursor route was utilized to fabricate SiC based inert matrix fuel (IMF). ► The effect of mixing and polymer infiltration and pyrolysis (PIP) cycles on the fabrication of the SiC IMF was investigated. ► A theoretical density of ∼86% has been achieved after one PIP cycle. ► Pore size distributions before and after PIP cycles have been determined. ► SEM images showed a “springback” effect for 600 MPa pressed pellets. - Abstract: The effect of mixing methods on the fabrication of silicon carbide (SiC) inert matrix fuel through a polymer precursor route was investigated in order to break up the agglomerates of the SiC particles observed in earlier studies. It was found that a high energy shaker mill could effectively break up the agglomerates and thereby achieve a higher pellet density. Moreover, it was found that the pellet density depended less on the pressing pressure, when the particles are well mixed. SEM images showed cracks caused by the springback effect on pellets with a high cold pressing pressure of 600 MPa, but no signs of springback effect were observed for the 200 MPa pressed pellets. The polymer infiltration and pyrolysis (PIP) cycles were used to further increase the pellet density and close the open pores. The first PIP cycle was found to increase the theoretical density of the pellets from 81.2% to 86.0% and close ∼50% of the open pores. The pore size distribution showed that most of the remaining open pores had diameters smaller than 10 nm. The successive second PIP cycle is not as effective on either the density or the pore size distribution because the small pores present before the second PIP cycle made the infiltration process difficult.

  18. Aqueous humor enhances the proliferation of rat retinal precursor cells in culture, and this effect is partially reproduced by ascorbic acid

    DEFF Research Database (Denmark)

    Yang, Jing; Klassen, Henry; Pries, Mette

    2006-01-01

    Aqueous humor has been shown to influence the proliferation of various ocular cell types, but the effect on immature retinal cells is not known. Here, the effect of pig aqueous humor on the proliferation of rat retinal precursor cells (RPCs) was investigated. RPCs were prepared from embryonic day...... 19 Sprague-Dawley rats and cultured in the presence or absence of aqueous humor from healthy pigs along with a medium consisting of Dulbecco's modified Eagle's medium:Ham's F-12 medium, N2 supplement, and epidermal growth factor. Proliferation was quantified by [(3)H]thymidine incorporation under...... different treatment conditions, and any associated morphological changes were noted. Potential active components of porcine aqueous humor were partially characterized by gel filtration chromatography, and the effect on RPC proliferation was determined. Results showed that adding 20% aqueous humor increased...

  19. Phenylpropanoid Metabolism in Suspension Cultures of Vanilla planifolia Andr. : II. Effects of Precursor Feeding and Metabolic Inhibitors.

    Science.gov (United States)

    Funk, C; Brodelius, P E

    1990-09-01

    Feeding of cinnamic acid and ferulic acid to non-treated and chitosan-treated cell suspension cultures of Vanilla planifolia resulted in the formation of trace amounts of p-hydroxy benzoic acid (5.2 micrograms per gram fresh weight of cells) and vanillic acid (6.4 micrograms per gram fresh weight of cells), respectively. Addition of a 4-hydroxycinnamate: CoA-ligase inhibitor, 3,4-(methylenedioxy)-cinnamic acid (MDCA), resulted in a reduced biosynthesis of ligneous material with a simultaneous significant increased vanillic acid formation (around 75 micrograms per gram fresh weight of cells). A K(1) of 100 micromolar for 4-hydroxycinnamate: CoA-ligase in a crude preparation was estimated for this inhibitor. It is suggested that the conversion of cinnamic acids into benzoic acids does not involve cinnamoyl CoA esters as intermediates. Feeding of (14)C-cinnamic acid and (14)C-ferulic acid to cells treated with MDCA indicate that cinnamic acid, but not ferulic acid, is a precursor of vanillic acid in these cultivated cells of V. planifolia.

  20. Effect of Temperature, Solvent and Precursor Concentration on Anti-Aggregation of ZnO Nanoparticles Prepared by Polyol Method.

    Science.gov (United States)

    Shanmugaml, Sathish; Muthu, Kesavan; Subramanian, Balakumar

    2016-01-01

    We have investigated the formation mechanism of ZnO microspheres in polyol medium. The synthesis conditions have been varied with respect to temperature, medium and Zn-precursor concentration. The X-ray diffraction (XRD) and Raman spectroscopy result shows that the prepared ZnO nanoparticles are hexagonal wurtzite crystal structure and quite crystalline in nature. High resolution transmission electron microscopy (HRTEM) image indicates that the microsphere consists of aggregated nanoparticles in the range of 6 nm to 15 nm. The samples prepared in ethylene glycol medium shows a characteristic ether bond vibration mode in FTIR and it is additionally confirmed by NMR analysis. Initially, the nanoparticles are self-assembled into loosely packed microsphere and then the particles are densely packed by ether bonds formed between the glycol molecules adsorbed on adjacent particles which then grow as perfect microspheres. The sample prepared in EG medium at 150 °C did not show much aggregation. This study proposes the possible mechanism for the formation of ZnO microsphere.

  1. Effect of precursor concentration on the structural and optical properties of ZnO nanorods prepared by hydrothermal method

    International Nuclear Information System (INIS)

    Lestari, Amie; Iwan, S.; Djuhana, Dede; Imawan, Cuk; Harmoko, Adhi; Fauzia, Vivi

    2016-01-01

    Zinc oxide (ZnO) nanorods has attractive properties for nanoscale optoelectronic applications, such as optical sensors, ultraviolet laser diodes, and photodetectors. ZnO nanorods, can be fabricated by simple and low cost chemical approach, such as hydrothermal method. In this method, the morphology, microstructure, optical and electrical properties of ZnO nanorods are highly determined by process parameters such as solvent, deposition time, deposition temperature as well as annealing condition. In this paper we report the fabrication of ZnO nanorods that were grown on transparent conducting indium tin oxide coated glass substrates. Initially, ZnO seed layers were deposited on heated substrates with temperature of 450 °C using ultrasonic spray pyrolysis method with frequency of 1.7 MHz and then grown by hydrothermal method with three different precursor concentrations, namely 0.02 M, 0.06 M, and 0.1 M. The surface morphology and structure were investigated by field emission scanning electron microscope (FESEM) and x-ray diffraction (XRD), while the optical properties were observed by photoluminescence (PL) and and UV VIS reflectance spectroscopy.

  2. The effect of cobalt substitution in crystal structure and vibrational modes of CuFe{sub 2}O{sub 4} powders obtained by polymeric precursor method

    Energy Technology Data Exchange (ETDEWEB)

    Silva, M.D.P.; Silva, F.C. [Departamento de Química, CCET, Universidade Federal do Maranhão, 65085-580 São Luís, MA (Brazil); Sinfrônio, F.S.M. [Departamento de Engenharia Elétrica, CCET, Universidade Federal do Maranhão, 65085-580 São Luís, MA (Brazil); Paschoal, A.R. [Departamento de Física, Universidade Federal do Ceará, Campus do Pici, 60455-760 Fortaleza, CE (Brazil); Silva, E.N. [Departamento de Física, CCET, Universidade Federal do Maranhão, 65085-580 São Luís, MA (Brazil); Paschoal, C.W.A., E-mail: paschoal@ufma.br [Departamento de Física, CCET, Universidade Federal do Maranhão, 65085-580 São Luís, MA (Brazil); Department of Materials Science and Engineering, University of California Berkeley, 94720-1760 Berkeley, CA (United States); Department of Physics, University of California Berkeley, 94720-7300 Berkeley, CA (United States)

    2014-01-25

    Highlights: • We synthesized mixed spinels by polymeric precursor method. • We investigated the structural and vibrational properties of the mixed. • We investigated the synthesis condition effects in these properties. • We proposed a complete phonon description for CuFe{sub 2}O{sub 4} and CoFe{sub 2}O{sub 4} spinels. -- Abstract: In this work Co–Cu mixed spinel Co{sub 1−x}Cu{sub x}Fe{sub 2}O{sub 4} powders were obtained by polymeric precursors method at several annealing temperatures between 700 and 1200 °C. The samples were characterized by means of X-ray powder diffraction, confirming the ideal inverse spinel structure for CoFe{sub 2}O{sub 4} sample and the tetragonal distorted inverse spinel structure for CuFe{sub 2}O{sub 4} sample. Based on FWHM evaluation, we estimated that crystallite sizes varies between 27 and 37 nm for the non-substituted samples. The optical-active modes were determined by infrared and Raman spectroscopies. The phonon spectra showed a local tetragonal distortion for mixed samples.

  3. The effect of linker of electrodes prepared from sol–gel ionic liquid precursor and carbon nanoparticles on dioxygen electroreduction bioelectrocatalysis

    International Nuclear Information System (INIS)

    Szot, Katarzyna; Lynch, Robert P.; Lesniewski, Adam; Majewska, Ewa; Sirieix-Plenet, Juliette; Gaillon, Laurent; Opallo, Marcin

    2011-01-01

    The effect of linker of three-dimensional, hydrophilic-carbon-nanoparticle film-electrodes prepared by layer-by-layer method on redox probe accumulation and bioelectrocatalytic dioxygen reduction was studied and compared for two different electrode scaffolds. The linker in both of these scaffolds was based on the same ionic liquid sol–gel precursor, 1-methyl-3-(3-trimethoxysilylpropyl) imidazolium bis(trifluoromethyl-sulfonyl)imide. The first electrode type was prepared by alternative immersion of tin doped indium oxide substrate in an aqueous suspension of carbon nanoparticles modified with phenyl sulphonic groups and a sol composed of ionic liquid sol–gel precursor and tetramethoxysilane. For the second electrode type sol was replaced by a methanolic suspension of silicate submicroparticles with appended imidazolium functional groups. In both films 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) anions accumulate irreversibly. In the case of the first electrode electrostatic attraction plays the more important role in comparison to the case of the second where stable adsorption of the redox probe takes place. After adsorption of bilirubin oxidase, electrodes obtained from sol and carbon nanoparticles exhibit modest bioelectrocatalytic activity towards dioxygen reduction at pH 4.8, however those obtained from oppositely charged particles are much more efficient. The magnitude of the associated catalytic current in both cases depends on the number of immersion and withdrawal steps. Interestingly, mediatorless catalysis at electrodes obtained from oppositely charged particles is more efficient than mediated catalysis.

  4. Precursor Additive Manufacturing Inventions

    Science.gov (United States)

    Roberts, C.; Bourell, D.

    2018-03-01

    Most modern Additive Manufacturing (AM) processes were invented and commercialized in a short period of time spanning 1984-2000. This paper reports on AM processes invented in the 1974-1987 time period, known as precursor AM processes. The critical difference between the two periods is public knowledge and utilization of distributed computing.

  5. Effect of the precursor solution concentration on the NiO thin film properties deposited by spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Reguig, B.A.; Khelil, A. [LPCM2E, Universite d' Oran Es Senia (Algerie); Regragui, M.; Morsli, M.; Bernede, J.C. [LAMP, Universite de Nantes, 2 Rue de la Houssiniere, BP 92208, 44322 Nantes Cedex 3 (France); Addou, M. [LOPCM, Universite d' Ibn Tofail, Kenitra (Maroc)

    2006-06-15

    NiO thin films have been deposited by chemical spray pyrolysis from nickel chloride hexahydrate (NiCl{sub 2}.6H{sub 2}O) solution in water. The substrate temperature during deposition is around 350{sup o}C. The solution flow rate was 10ml/min. The nickel chloride concentration in the solvent has been used as parameter. It varies from 0.05 to 0.5M. It is shown that the NiO film properties depend strongly on the nickel chloride concentration. Below 0.3M, the final thickness of a film deposited using 50ml of solution is around 0.5{mu}m. From 0.3 to 0.5M the thickness is around 3{mu}m. There is a threshold value for the different film properties when the precursor concentration varies between C=0.2 and 0.3M. The oxygen concentration present in the films decreases from 1, in the case of small molar concentration, to 0.86 for 0.3M and more. In the X-ray diffraction diagram, the more intense contribution is systematically the (111) peak, while the (200) diffraction peak is small. This last peak increases slowly up to 0.3M with the NiCl{sub 2} concentration, and then it stabilizes. Also, the conductivity decreases when the molar concentration of NiCl{sub 2} increases, to stabilize at around 0.3M. Moreover, while, as expected, the films are p-type when the molar concentration is smaller than 0.3M, they becomes n-type for higher concentrations. The increase in the deposition rate induces a significant increase in the grow rate of the NiO thin film, which can explain the decrease in grain orientation and oxygen concentration. The threshold value experimentally measured should be related to the reaction kinetics between Ni and O during spray pyrolysis. NiO is shown as a p-type extrinsic semiconductor in which Ni vacancies lead to p-type conductivity. Moreover, the presence of Ni{sup 3+} in the films, as shown by XPS and the brown color of the films, enhances the p-type character of the films. When the O/Ni at% ratio decreases as the precursor concentration increases, the Ni

  6. The effect of glia-glia interactions on oligodendrocyte precursor cell biology during development and in demyelinating diseases

    Directory of Open Access Journals (Sweden)

    Diego eClemente

    2013-12-01

    Full Text Available Oligodendrocyte precursor cells (OPCs originate in specific areas of the developing central nervous system (CNS. Once generated, they migrate towards their destinations where they differentiate into mature oligodendrocytes. In the adult, 5-8% of all cells in the CNS are OPCs, cells that retain the capacity to proliferate, migrate and differentiate into oligodendrocytes. Indeed, these endogenous OPCs react to damage in demyelinating diseases, like multiple sclerosis (MS, representing a key element in spontaneous remyelination. In the present work, we review the specific interactions between OPCs and other glial cells (astrocytes, microglia during CNS development and in the pathological scenario of MS. We focus on: i the role of astrocytes in maintaining the homeostasis and spatial distribution of different secreted cues that determine OPC proliferation, migration and differentiation during CNS development; ii the role of microglia and astrocytes in the redistribution of iron, which is crucial for myelin synthesis during CNS development and for myelin repair in MS; iii how microglia secrete different molecules, e.g. growth factors, that favor the recruitment of OPCs in acute phases of MS lesions; and iv how astrocytes modify the extracellular matrix in MS lesions, affecting the ability of OPCs to attempt spontaneous remyelination. Together, these issues demonstrate how both astroglia and microglia influence OPCs in physiological and pathological situations, reinforcing the concept that both development and neural repair are complex and global phenomena. Understanding the molecular and cellular mechanisms that control OPC survival, proliferation, migration and differentiation during development, as well as in the mature CNS, may open new opportunities in the search for reparative therapies in demyelinating diseases like MS.

  7. Microwave Assisted Synthesis of ZnO Nanoparticles: Effect of Precursor Reagents, Temperature, Irradiation Time, and Additives on Nano-ZnO Morphology Development

    Directory of Open Access Journals (Sweden)

    Gastón P. Barreto

    2013-01-01

    Full Text Available The effect of different variables (precursor reagents, temperature, irradiation time, microwave radiation power, and additives addition on the final morphology of nano-ZnO obtained through the microwave assisted technique has been investigated. The characterization of the samples has been carried out by field emission scanning electron microscopy (FE-SEM in transmission mode, infrared (FTIR, UV-Vis spectroscopy, and powder X-ray diffraction (XRD. The results showed that all the above-mentioned variables influenced to some extent the shape and/or size of the synthetized nanoparticles. In particular, the addition of an anionic surfactant (sodium di-2-ethylhexyl-sulfosuccinate (AOT to the reaction mixture allowed the synthesis of smaller hexagonal prismatic particles (100 nm, which show a significant increase in UV absorption.

  8. Transplanted astrocytes derived from BMP- or CNTF-treated glial-restricted precursors have opposite effects on recovery and allodynia after spinal cord injury

    Directory of Open Access Journals (Sweden)

    Davies Jeannette E

    2008-09-01

    Full Text Available Abstract Background Two critical challenges in developing cell-transplantation therapies for injured or diseased tissues are to identify optimal cells and harmful side effects. This is of particular concern in the case of spinal cord injury, where recent studies have shown that transplanted neuroepithelial stem cells can generate pain syndromes. Results We have previously shown that astrocytes derived from glial-restricted precursor cells (GRPs treated with bone morphogenetic protein-4 (BMP-4 can promote robust axon regeneration and functional recovery when transplanted into rat spinal cord injuries. In contrast, we now show that transplantation of GRP-derived astrocytes (GDAs generated by exposure to the gp130 agonist ciliary neurotrophic factor (GDAsCNTF, the other major signaling pathway involved in astrogenesis, results in failure of axon regeneration and functional recovery. Moreover, transplantation of GDACNTF cells promoted the onset of mechanical allodynia and thermal hyperalgesia at 2 weeks after injury, an effect that persisted through 5 weeks post-injury. Delayed onset of similar neuropathic pain was also caused by transplantation of undifferentiated GRPs. In contrast, rats transplanted with GDAsBMP did not exhibit pain syndromes. Conclusion Our results show that not all astrocytes derived from embryonic precursors are equally beneficial for spinal cord repair and they provide the first identification of a differentiated neural cell type that can cause pain syndromes on transplantation into the damaged spinal cord, emphasizing the importance of evaluating the capacity of candidate cells to cause allodynia before initiating clinical trials. They also confirm the particular promise of GDAs treated with bone morphogenetic protein for spinal cord injury repair.

  9. Effect of regional precursor emission controls on long-range ozone transport – Part 2: Steady-state changes in ozone air quality and impacts on human mortality

    Directory of Open Access Journals (Sweden)

    J. J. West

    2009-08-01

    Full Text Available Large-scale changes in ozone precursor emissions affect ozone directly in the short term, and also affect methane, which in turn causes long-term changes in ozone that affect surface ozone air quality. Here we assess the effects of changes in ozone precursor emissions on the long-term change in surface ozone via methane, as a function of the emission region, by modeling 10% reductions in anthropogenic nitrogen oxide (NOx emissions from each of nine world regions. Reductions in NOx emissions from all world regions increase methane and long-term surface ozone. While this long-term increase is small compared to the intra-regional short-term ozone decrease, it is comparable to or larger than the short-term inter-continental ozone decrease for some source-receptor pairs. The increase in methane and long-term surface ozone per ton of NOx reduced is greatest in tropical and Southern Hemisphere regions, exceeding that from temperate Northern Hemisphere regions by roughly a factor of ten. We also assess changes in premature ozone-related human mortality associated with regional precursor reductions and long-range transport, showing that for 10% regional NOx reductions, the strongest inter-regional influence is for emissions from Europe affecting mortalities in Africa. Reductions of NOx in North America, Europe, the Former Soviet Union, and Australia are shown to reduce more mortalities outside of the source regions than within. Among world regions, NOx reductions in India cause the greatest number of avoided mortalities per ton, mainly in India itself. Finally, by increasing global methane, NOx reductions in one hemisphere tend to cause long-term increases in ozone concentration and mortalities in the opposite hemisphere. Reducing emissions of methane, and to a lesser extent carbon monoxide and non-methane volatile organic compounds, alongside NOx reductions would

  10. Effective long-term immunosuppression in rats by subcutaneously implanted sustained-release tacrolimus pellet: Effect on spinally grafted human neural precursor survival

    Czech Academy of Sciences Publication Activity Database

    Ševc, J.; Goldberg, D.; van Gorp, S.; Leerink, M.; Juhás, Štefan; Juhásová, Jana; Marsala, S.; Hruška-Plocháň, Marian; Hefferan, M. P.; Motlík, Jan; Rypáček, František; Machová, Luďka; Kakinohana, O.; Santucci, C.; Johe, K.; Lukáčová, N.; Yamada, K.; Bui, J. D.; Marsala, M.

    2013-01-01

    Roč. 248, October (2013), s. 85-99 ISSN 0014-4886 R&D Projects: GA TA ČR TA01011466; GA MŠk ED2.1.00/03.0124 Institutional support: RVO:67985904 ; RVO:61389013 Keywords : immunosuppression * xenograft * human neural precursors Subject RIV: FH - Neurology; CD - Macromolecular Chemistry (UMCH-V) Impact factor: 4.617, year: 2013

  11. The eukaryotic translation elongation factor eEF1A2 induces neoplastic properties and mediates tumorigenic effects of ZNF217 in precursor cells of human ovarian carcinomas

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yu; Wong, Nicholas; Guan, Yinghui; Salamanca, Clara M.; Cheng, Jung Chien; Lee, Jonathan M.; Gray, Joe W.; Auersperg, Nelly

    2008-04-25

    Ovarian epithelial carcinomas (OEC) frequently exhibit amplifications at the 20q13 locus which is the site of several oncogenes, including the eukaryotic elongation factor EEF1A2 and the transcription factor ZNF217. We reported previously that overexpressed ZNF217 induces neoplastic characteristics in precursor cells of OEC. Unexpectedly, ZNF217, which is a transcriptional repressor, enhanced expression of eEF1A2. In this study, array comparative genomic hybridization, single nucleotide polymorphism and Affymetrix analysis of ZNF217-overexpressing cell lines confirmed consistently increased expression of eEF1A2 but not of other oncogenes, and revealed early changes in EEF1A2 gene copy numbers and increased expression at crisis during immortalization. We defined the influence of eEF1A2 overexpression on immortalized ovarian surface epithelial cells, and investigated interrelationships between effects of ZNF217 and eEF1A2 on cellular phenotypes. Lentivirally induced eEF1A2 overexpression caused delayed crisis, apoptosis resistance and increases in serum-independence, saturation densities, and anchorage independence. siRNA to eEF1A2 reversed apoptosis resistance and reduced anchorage independence in eEF1A2-overexpressing lines. Remarkably, siRNA to eEF1A2 was equally efficient in inhibiting both anchorage independence and resistance to apoptosis conferred by ZNF217 overexpression. Our data define neoplastic properties that are caused by eEF1A2 in nontumorigenic ovarian cancer precursor cells, and suggest that eEF1A2 plays a role in mediating ZNF217-induced neoplastic progression.

  12. Cell-line specific protection by berry polyphenols against hydrogen peroxide challenge and lack of effect on metabolism of amyloid precursor protein.

    Science.gov (United States)

    Papandreou, Magdalini A; Tsachaki, Maria; Efthimiopoulos, Spiros; Klimis-Zacas, Dorothy; Margarity, Marigoula; Lamari, Fotini N

    2012-07-01

    Amyloid precursor protein (APP) altered metabolism, Aβ-overproduction/aggregation and oxidative stress are implicated in the development of Alzheimer's disease pathology. Based on our previous data indicating that administration of a polyphenol-rich (PrB) blueberry extract (from wild Vaccinium angustifolium) is memory enhancing in healthy mice and in order to delineate the neuroprotective mechanisms, this study investigated the antioxidant effects of PrB in H₂O₂-induced oxidative damage, Aβ peptide fibrillogenesis and APP metabolism. PrB suppressed H₂O₂-initiated oxidation (DCF assay) and cell death (MTT assay) in SH-SY5Y cells. Protective effects were observed on Chinese hamster ovary (CHO) cells overexpressing APP770 carrying the mutation Val717Phe only at high concentrations, while further damage on HEK293 cells was induced after co-treatment with 250 µM H₂O₂ and PrB in comparison with H₂O₂ alone. Using the thioflavine T assay, blueberry polyphenols inhibited Aβ-aggregation (~70%, 15 µg/mL) in a time-dependent manner, while in the CHO(APP770) cells it had no effect on APP metabolism as assessed by western blot. The results suggest that blueberry polyphenols exhibit antioxidant and/or pro-oxidant properties according to the cellular environment and have no effect on APP metabolism. Copyright © 2011 John Wiley & Sons, Ltd.

  13. Precursor of color superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Kitazawa, M. [Kyoto Univ., Dept. of Physics, Kyoto (Japan); Koide, T.; Kunihiro, T. [Kyoto Univ., Yukawa Institute for Theoretical Physics, Kyoto (Japan); Nemoto, Y. [Brookhaven National Laboratory, RIKEN BNL Research Center, Upton, NY (United States)

    2002-09-01

    We investigate possible precursory phenomena of color superconductivity in quark matter at finite temperature T with use of a simple Nambu-Jona-Lasinio model. It is found that the fluctuating pair field exists with a prominent strength even well above the critical temperature T{sub c}. We show that the collective pair field has a complex energy located in the second Riemann sheet, which approaches the origin as T is lowered to T{sub c}. We discuss the possible relevance of the precursor to the observables to be detected in heavy ion collisions. (author)

  14. The effect of cationic disorder on the optical and electrochemical behavior of nanocrystalline ZnO prepared from peroxide precursors

    Czech Academy of Sciences Publication Activity Database

    Makarova, Marina; Macounová, Kateřina; Krtil, Petr

    2006-01-01

    Roč. 10, č. 5 (2006), s. 320-328 ISSN 1432-8488 R&D Projects: GA AV ČR 1ET400400413 Institutional research plan: CEZ:AV0Z40400503 Keywords : coherent domain * zinc oxide * (photo)electrochemistry * quantum size effects Subject RIV: CG - Electrochemistry Impact factor: 1.542, year: 2006

  15. Ionic liquid nanotribology: stiction suppression and surface induced shear thinning.

    Science.gov (United States)

    Asencio, Rubén Álvarez; Cranston, Emily D; Atkin, Rob; Rutland, Mark W

    2012-07-03

    The friction and adhesion between pairs of materials (silica, alumina, and polytetrafluoroethylene) have been studied and interpreted in terms of the long-ranged interactions present. In ambient laboratory air, the interactions are dominated by van der Waals attraction and strong adhesion leading to significant frictional forces. In the presence of the ionic liquid (IL) ethylammonium nitrate (EAN) the van der Waals interaction is suppressed and the attractive/adhesive interactions which lead to "stiction" are removed, resulting in an at least a 10-fold reduction in the friction force at large applied loads. The friction coefficient for each system was determined; coefficients obtained in air were significantly larger than those obtained in the presence of EAN (which ranged between 0.1 and 0.25), and variation in the friction coefficients between systems was correlated with changes in surface roughness. As the viscosity of ILs can be relatively high, which has implications for the lubricating properties, the hydrodynamic forces between the surfaces have therefore also been studied. The linear increase in repulsive force with speed, expected from hydrodynamic interactions, is clearly observed, and these forces further inhibit the potential for stiction. Remarkably, the viscosity extracted from the data is dramatically reduced compared to the bulk value, indicative of a surface ordering effect which significantly reduces viscous losses.

  16. Diagnosis of the anaerobic reject water effects on WWTP operational characteristics as a precursor of bulking and foaming.

    Science.gov (United States)

    Erdirençelebi, Dilek; Küçükhemek, Murat

    2015-01-01

    This study investigates the effects observed on operational parameters in a large and full-scale wastewater treatment plant subjected to anaerobic reject water (ARW) diversion off the main line for a 3-month period and further monitoring for a 2-year period. The plant's secondary unit consists of a two-stage plug-flow-modified Bardenpho process receiving wastewater from both municipal and industrial origins. As a result, ARW was found to have a direct effect on bulking in secondary clarifiers and foaming in anaerobic digesters (AD) despite its relatively small flow rate. During the cut-off period a highly stable sludge volume index at 80 mL g(-1) level was obtained in the secondary clarifiers, effluent suspended solids concentration was reduced and continuous feeding to AD was recovered. Sludge density increased in the thickeners during hot season. Secondary clarifiers showed good and stable settleability despite low dissolved oxygen, food/microorganism ratio and high sludge retention time and ammonium levels in the biological unit. The bulking and foaming effect was presented on the plant's internal flow balance. ARW needs serious consideration for elimination by appropriate technologies because of its high potential as a multi-dimensional pollutant source, not only as a carrier of nutrients but also as a possible carrier of filamentous bacteria, which might promote chronic seeding and retention in the system.

  17. The effect of simvastatin treatment on the amyloid precursor protein and brain cholesterol metabolism in patients with Alzheimer's disease

    DEFF Research Database (Denmark)

    Hoglund, K; Thelen, K M; Syversen, S

    2005-01-01

    as on cognitive decline in patients with AD. Despite biochemical data suggesting that treatment with 20 mg/day of simvastatin for 12 months does affect the brain cholesterol metabolism, we did not find any change in CSF or plasma levels of beta-amyloid (Abeta)(1-42). However, by analysis of APP isoforms, we found...... with AD have been treated with simvastatin (20 mg/day) for 12 months. The aim was to further investigate the effect of simvastatin treatment on cerebrospinal fluid (CSF) biomarkers of APP processing, AD biomarkers as total tau and tau phosphorylated at threonine 181, brain cholesterol metabolism as well...

  18. Effect of Metal Chelators on γ-Secretase Indicates That Calcium and Magnesium Ions Facilitate Cleavage of Alzheimer Amyloid Precursor Substrate

    Directory of Open Access Journals (Sweden)

    Michael Ho

    2011-01-01

    Full Text Available Gamma-secretase is involved in the production of Aβ amyloid peptides. It cleaves the transmembrane domain of the amyloid precursor protein (APP at alternative sites to produce Aβ and the APP intracellular domain (AICD. Metal ions play an important role in Aβ aggregation and metabolism, thus metal chelators and ligands represent potential therapeutic agents for AD treatment. A direct effect of metal chelators on γ-secretase has not yet been investigated. The authors used an in vitro  γ-secretase assay consisting of cleavage of APP C100-3XFLAG by endogenous γ-secretase from rodent brains and human neuroblastoma SH-SY5Y, and detected AICD production by western blotting. Adding metalloprotease inhibitors to the reaction showed that clioquinol, phosphoramidon, and zinc metalloprotease inhibitors had no significant effect on γ-secretase activity. In contrast, phenanthroline, EDTA, and EGTA markedly decreased γ-secretase activity that could be restored by adding back calcium and magnesium ions. Mg2+ stabilized a 1,000 kDa presenilin 1 complex through blue native gel electrophoresis and size-exclusion chromatography. Data suggest that Ca2+ and Mg2+ stabilize γ-secretase and enhance its activity.

  19. Acidogenic fermentation of the organic fraction of municipal solid waste and cheese whey for bio-plastic precursors recovery - Effects of process conditions during batch tests.

    Science.gov (United States)

    Girotto, Francesca; Lavagnolo, Maria Cristina; Pivato, Alberto; Cossu, Raffaello

    2017-12-01

    The problem of fossil fuels dependency is being addressed through sustainable bio-fuels and bio-products production worldwide. At the base of this bio-based economy there is the efficient use of biomass as non-virgin feedstock. Through acidogenic fermentation, organic waste can be valorised in order to obtain several precursors to be used for bio-plastic production. Some investigations have been done but there is still a lack of knowledge that must be filled before moving to effective full scale plants. Acidogenic fermentation batch tests were performed using food waste (FW) and cheese whey (CW) as substrates. Effects of nine different combinations of substrate to inoculum (S/I) ratio (2, 4, and 6) and initial pH (5, 7, and 9) were investigated for metabolites (acetate, butyrate, propionate, valerate, lactate, and ethanol) productions. Results showed that the most abundant metabolites deriving from FW fermentation were butyrate and acetate, mainly influenced by the S/I ratio (acetate and butyrate maximum productions of 21.4 and 34.5g/L, respectively, at S/I=6). Instead, when dealing with CW, lactate was the dominant metabolite significantly correlated with pH (lactate maximum production of 15.7g/L at pH = 9). Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Effectiveness of different methods of preparing seedlings of cereals under sterile conditions for investigations of nucleic acids using radioactive precursors

    Directory of Open Access Journals (Sweden)

    W. Filek

    2015-01-01

    Full Text Available On seedlings grown from grain not sterilized in advance bacteria numbered more than 108 microorganisms per one gram of fresh weight. Washing of seedlings with cetyltrimethylammonium bromide or sodium lauryl sulphate solutions reduced the number of bacteria several times. Sterilization of grains prior to planting with sodium hypochlorite and germination on solid substratum (perlit reduced the number of bacteria to below 104 microorganisms to one gram of fresh weight. If germination was, however, in water, bacteria on the seedlings were approximately as numerous as on seedlings from mon-sterilized grains. Of the three antibiotics tested (streptomycin, chloramphenicol, penicillin the most effective against the bacteria of wheat seedlings was chloramphenicol coupled with streptomycin; of antibiotics used singly chloramphenicol was best.

  1. Effect of Growth Temperature on Bamboo-shaped Carbon–Nitrogen (C–N Nanotubes Synthesized Using Ferrocene Acetonitrile Precursor

    Directory of Open Access Journals (Sweden)

    Dobal PramodSingh

    2008-01-01

    Full Text Available Abstract This investigation deals with the effect of growth temperature on the microstructure, nitrogen content, and crystallinity of C–N nanotubes. The X-ray photoelectron spectroscopic (XPS study reveals that the atomic percentage of nitrogen content in nanotubes decreases with an increase in growth temperature. Transmission electron microscopic investigations indicate that the bamboo compartment distance increases with an increase in growth temperature. The diameter of the nanotubes also increases with increasing growth temperature. Raman modes sharpen while the normalized intensity of the defect mode decreases almost linearly with increasing growth temperature. These changes are attributed to the reduction of defect concentration due to an increase in crystal planar domain sizes in graphite sheets with increasing temperature. Both XPS and Raman spectral observations indicate that the C–N nanotubes grown at lower temperatures possess higher degree of disorder and higher N incorporation.

  2. Effect of the Milling Time of the Precursors on the Physical Properties of Sprayed Aluminum-Doped Zinc Oxide (ZnO:Al Thin Films

    Directory of Open Access Journals (Sweden)

    María De La Luz Olvera

    2012-08-01

    Full Text Available Aluminum doped zinc oxide (ZnO:Al thin films were deposited on soda-lime glass substrates by the chemical spray technique. The atomization of the solution was carried out by ultrasonic excitation. Six different starting solutions from both unmilled and milled Zn and Al precursors, dissolved in a mix of methanol and acetic acid, were prepared. The milling process was carried out using a planetary ball mill at a speed of 300 rpm, and different milling times, namely, 15, 25, 35, 45, and 60 min. Molar concentration, [Al]/[Zn] atomic ratio, deposition temperature and time, were kept at constant values; 0.2 M, 3 at.%, 475 °C, and 10 min, respectively. Results show that, under the same deposition conditions, electrical resistivities of ZnO:Al thin films deposited from milled precursors are lower than those obtained for films deposited from unmilled precursors. X-ray diffraction analysis revealed that all films display a polycrystalline structure, fitting well with the hexagonal wurtzite structure. Changes in surface morphology were observed by scanning electron microscopy (SEM as well, since films deposited from unmilled precursors show triangular shaped grains, in contrast to films deposited from 15 and 35 min milled precursors that display thin slices with hexagonal shapes. The use of milled precursors to prepare starting solutions for depositing ZnO:Al thin films by ultrasonic pyrolysis influences their physical properties.

  3. Understanding the effectiveness of precursor reductions in lowering 8-hr ozone concentrations--Part II. The eastern United States.

    Science.gov (United States)

    Reynolds, Steven D; Blanchard, Charles L; Ziman, Stephen D

    2004-11-01

    Analyses of ozone (O3) measurements in conjunction with photochemical modeling were used to assess the feasibility of attaining the federal 8-hr O3 standard in the eastern United States. Various combinations of volatile organic compound (VOC) and oxides of nitrogen (NOx) emission reductions were effective in lowering modeled peak 1-hr O3 concentrations. VOC emissions reductions alone had only a modest impact on modeled peak 8-hr O3 concentrations. Anthropogenic NOx emissions reductions of 46-86% of 1996 base case values were needed to reach the level of the 8-hr standard in some areas. As NOx emissions are reduced, O3 production efficiency increases, which accounts for the less than proportional response of calculated 8-hr O3 levels. Such increases in O3 production efficiency also were noted in previous modeling work for central California. O3 production in some urban core areas, such as New York City and Chicago, IL, was found to be VOC-limited. In these areas, moderate NOx emissions reductions may be accompanied by increases in peak 8-hr O3 levels. The findings help to explain differences in historical trends in 1- and 8-hr O3 levels and have serious implications for the feasibility of attaining the 8-hr O3 standard in several areas of the eastern United States.

  4. Study of directivity effect on electromagnetic emissions in the HF band as earthquake precursors: Preliminary results on field observations

    Science.gov (United States)

    Stavrakas, I.; Clarke, M.; Koulouras, G.; Stavrakakis, G.; Nomicos, C.

    2007-02-01

    This work focuses on the use of electromagnetic emissions (EM) in the HF band as a warning event for earthquakes. EM at HF components 41 MHz and 46 MHz were monitored and recorded from eight field stations in Greece and correlated with seismological events. Directivity effect raised since EM emissions at specific station locations were correlated to earthquake events from prescribed regions. EM recordings during 1999 were used and by visual inspection were associated to most of the earthquake events greater than 5R. Using these observations a novel algorithm based on the ratio of short term to long term signal average, together with a prediction rules set derived from 1999's EM emissions study were developed to combine results from several field stations. Performance of the system was promising, but was dependent on the geographic area of interest. Overall performance for earthquakes events of magnitude greater than 5.7 R was 75% of seismic events were correctly predicted by EM activity, while 25% were not predicted.

  5. The role of internal energy of polyatomic projectile ions in surface-induced dissociation

    Czech Academy of Sciences Publication Activity Database

    Quayyum, A.; Tepnual, T.; Mair, C.; Matt-Leubner, S.; Scheier, P.; Herman, Zdeněk; Märk, T. D.

    2003-01-01

    Roč. 376, 5-6 (2003), s. 539-547 ISSN 0009-2614 R&D Projects: GA ČR GA203/00/0632 Institutional research plan: CEZ:AV0Z4040901 Keywords : physical chemistry * surface-induced dissociations * interactions Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.438, year: 2003

  6. Surface-Induced Dissociation of Polyatomic Hydrocarbon Projectile Ions with Different Initial Internal Energy Content

    Czech Academy of Sciences Publication Activity Database

    Qayyum, A.; Herman, Zdeněk; Tepnual, T.; Mair, C.; Matt-Leubner, S.; Scheier, P.; Märk, T. D.

    2004-01-01

    Roč. 108, č. 1 (2004), s. 1-8 ISSN 1089-5639 R&D Projects: GA ČR GA203/00/0632 Grant - others:XE(CZ) EURATOM-IPP.CR Institutional research plan: CEZ:AV0Z4040901 Keywords : surface induced * polyatomic ions Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.639, year: 2004

  7. Identified EM Earthquake Precursors

    Science.gov (United States)

    Jones, Kenneth, II; Saxton, Patrick

    2014-05-01

    Many attempts have been made to determine a sound forecasting method regarding earthquakes and warn the public in turn. Presently, the animal kingdom leads the precursor list alluding to a transmission related source. By applying the animal-based model to an electromagnetic (EM) wave model, various hypotheses were formed, but the most interesting one required the use of a magnetometer with a differing design and geometry. To date, numerous, high-end magnetometers have been in use in close proximity to fault zones for potential earthquake forecasting; however, something is still amiss. The problem still resides with what exactly is forecastable and the investigating direction of EM. After a number of custom rock experiments, two hypotheses were formed which could answer the EM wave model. The first hypothesis concerned a sufficient and continuous electron movement either by surface or penetrative flow, and the second regarded a novel approach to radio transmission. Electron flow along fracture surfaces was determined to be inadequate in creating strong EM fields, because rock has a very high electrical resistance making it a high quality insulator. Penetrative flow could not be corroborated as well, because it was discovered that rock was absorbing and confining electrons to a very thin skin depth. Radio wave transmission and detection worked with every single test administered. This hypothesis was reviewed for propagating, long-wave generation with sufficient amplitude, and the capability of penetrating solid rock. Additionally, fracture spaces, either air or ion-filled, can facilitate this concept from great depths and allow for surficial detection. A few propagating precursor signals have been detected in the field occurring with associated phases using custom-built loop antennae. Field testing was conducted in Southern California from 2006-2011, and outside the NE Texas town of Timpson in February, 2013. The antennae have mobility and observations were noted for

  8. Effect of a short- and long-term treatment with Ginkgo biloba extract on amyloid precursor protein levels in a transgenic mouse model relevant to Alzheimer's disease.

    Science.gov (United States)

    Augustin, Sabine; Rimbach, Gerald; Augustin, Kay; Schliebs, Reinhard; Wolffram, Siegfried; Cermak, Rainer

    2009-01-15

    Several clinical trials have reported beneficial effects of the Ginkgo biloba extract EGb761 in the prevention and therapy of cognitive disorders including Alzheimer's disease (AD). The aim of the present long-term feeding trial was to study the impact of dietary EGb761 on Amyloid precursor protein (APP) metabolism in mice transgenic for human APP (Tg2576). Tg2576 mice were fed diets with and without EGb761 (300 mg/kg diet) for 1 and 16 months, respectively. Long-term treatment (16 months) with EGb761 significantly lowered human APP protein levels by approximately 50% as compared to controls in the cortex but not in the hippocampus. However, APP levels were not affected by EGb761 in young mice. Current data indicate that APP seems to be an important molecular target of EGb761 in relation to the duration of the Ginkgo biloba treatment and/or the age of the animals. Potential neuroprotective properties of EGb761 may be, at least partly, related to its APP lowering activity.

  9. Effects of Intermittent Administration of Parathyroid Hormone (1-34 on Bone Differentiation in Stromal Precursor Antigen-1 Positive Human Periodontal Ligament Stem Cells

    Directory of Open Access Journals (Sweden)

    Xiaoxiao Wang

    2016-01-01

    Full Text Available Periodontitis is the most common cause of tooth loss and bone destruction in adults worldwide. Human periodontal ligament stem cells (hPDLSCs may represent promising new therapeutic biomaterials for tissue engineering applications. Stromal precursor antigen-1 (STRO-1 has been shown to have roles in adherence, proliferation, and multipotency. Parathyroid hormone (PTH has been shown to enhance proliferation in osteoblasts. Therefore, in this study, we aimed to compare the functions of STRO-1(+ and STRO-1(− hPDLSCs and to investigate the effects of PTH on the osteogenic capacity of STRO-1(+ hPDLSCs in order to evaluate their potential applications in the treatment of periodontitis. Our data showed that STRO-1(+ hPDLSCs expressed higher levels of the PTH-1 receptor (PTH1R than STRO-1(− hPDLSCs. In addition, intermittent PTH treatment enhanced the expression of PTH1R and osteogenesis-related genes in STRO-1(+ hPDLSCs. PTH-treated cells also exhibited increased alkaline phosphatase activity and mineralization ability. Therefore, STRO-1(+ hPDLSCs represented a more promising cell resource for biomaterials and tissue engineering applications. Intermittent PTH treatment improved the capacity for STRO-1(+ hPDLSCs to repair damaged tissue and ameliorate the symptoms of periodontitis.

  10. Heat-up Synthesis of Ag-In-S and Ag-In-S/ZnS Nanocrystals: Effect of Indium Precursors on Their Optical Properties.

    Science.gov (United States)

    Chen, Siqi; Ahmadiantehrani, Mojtaba; Zhao, Jialong; Zhu, Shaihong; Mamalis, Athanasios G; Zhu, Xiaoshan

    2016-04-25

    Cadmium-free I-III-VI nanocrystals (NCs) have recently attracted much research interests due to their excellent optical properties and low toxicity. In this work, with a simple heat-up synthetic system to prepare high quality Ag-In-S (AIS) NCs and their core/shell structures (AIS/ZnS NCs), we investigated the effect of different indium precursors (indium acetate and indium chloride) on NC optical properties. The measurements on photoluminescence spectra of AIS NCs show that the photoluminescence peak-wavelength of AIS NCs using indium acetate is in the range from 596 to 604 nm, and that of AIS NCs using indium chloride is from 641 to 660 nm. AIS and AIS/ZnS NCs using indium acetate present around 15% and 40% QYs, and both AIS and AIS/ZnS NCs using indium chloride present around 31% QYs. The photoluminescence decay study indicates that the lifetime parameters of AIS and AIS/ZnS using indium chloride are 2 ~ 4 times larger than those of AIS and AIS/ZnS NCs using indium acetate. Moreover, AIS NCs using indium chloride have a slower photobleaching dynamics than AIS NCs using indium acetate, and ZnS shell coating on both types of AIS NCs significantly enhances their photostability against UV exposure. We believe that the unique optical properties of AIS and AIS/ZnS NCs will open an avenue for these materials to be employed in broad electronic or biomedical applications.

  11. Charge exchange, surface-induced dissociation and reactions of doubly charged molecular ions SF42+ upon impact on a stainless steel surface: A comparison with surface-induced dissociation of singly charged SF4+ molecular ions

    Czech Academy of Sciences Publication Activity Database

    Feketeová, L.; Grill, V.; Zappa, F.; Endstrasser, N.; Rasul, B.; Herman, Zdeněk; Scheier, P.; Märk, T. D.

    2008-01-01

    Roč. 276, č. 1 (2008), s. 37-42 ISSN 1387-3806 Institutional research plan: CEZ:AV0Z40400503 Keywords : doubly charged ion * surface-induced dissociations * surface-induced reaction * charge exchange Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.445, year: 2008

  12. Assessing the effects of oil sands related ozone precursor emissions on ambient ozone levels in the Alberta oil sands region, Canada

    Science.gov (United States)

    Cho, Sunny; Vijayaraghavan, Krish; Spink, David; Cosic, Biljana; Davies, Mervyn; Jung, Jaegun

    2017-11-01

    A study was undertaken to determine whether, and the extent to which, increased ground-level ozone (O3) precursor emissions from oil sands development have impacted ambient air quality in the north-eastern Alberta, Canada, over the period 1998 to 2012. Temporal trends in emissions of O3 precursors (NOx and VOC) and ambient air concentrations of O3 precursors, and O3 were examined using the Theil-Sen statistical analysis method. Statistically significant correlations between NOx emissions and ambient NOx concentrations were found mainly near surface (open-pit) mining areas where mine fleets are a large source of NOx emissions. No statistically significant trends in the 4th highest daily maximum 8-hr average O3 at any of the continuous and passive ambient air monitoring stations were found. A significant long-term decrease in monthly averaged O3 is observed at some ambient monitoring sites in summer. A visual examination of long-term variations in annual NOx and VOC emissions and annual 4th highest daily maximum 8-hr O3 concentrations does not reveal any indication of a correlation between O3 concentrations and O3 precursor emissions or ambient levels in the study area. Despite a significant increase in oil sands NOx emissions (8%/yr), there is no statistically significant increase in long-term O3 concentrations at any of monitoring stations considered. This suggests that there is surplus NOx available in the environment which results in a titration of ambient O3 in the areas that have ambient monitoring. The limited ambient O3 monitoring data distant from NOx emission sources makes it impossible to assess the impact of these increased O3 precursor levels on O3 levels on a regional scale. As a precautionary measure, the increasing oil sands development O3 precursor emissions would require that priority be given to the management of these emissions to prevent possible future O3 ambient air quality issues.

  13. Expansion and characterization of ventral mesencephalic precursor cells: effect of mitogens and investigation of FA1 as a potential dopaminergic marker

    DEFF Research Database (Denmark)

    Jensen, Pia; Bauer, Matthias; Jensen, Charlotte H

    2007-01-01

    Methods for identification and in vitro expansion of ventral mesencephalic dopaminergic precursor cells are of interest in the search for transplantable neurons for cell therapy in Parkinson's disease (PD). We investigated the potential use of fibroblast growth factor 2 (FGF2) and fibroblast growth...... factor 8 (FGF8) for expansion of such dopaminergic precursor cells, and fetal antigen-1 (FA1), a secreted neuronal protein of unknown function, as a non-invasive dopaminergic marker. Tissue from embryonic day (ED) 12 rat ventral mesencephalon was dissociated mechanically and cultured for 4 days...

  14. Report on Fukushima Daiichi NPP precursor events

    International Nuclear Information System (INIS)

    2014-01-01

    The main questions to be answered by this report were: The Fukushima Daiichi NPP accident, could it have been prevented? If there is a next severe accident, may it be prevented? To answer the first question, the report addressed several aspects. First, the report investigated whether precursors to the Fukushima Daiichi NPP accident existed in the operating experience; second, the reasons why these precursors did not evolve into a severe accident. Third, whether lessons learned from these precursor events were adequately considered by member countries; and finally, if the operating experience feedback system needs to be improved, based on the previous analysis. To address the second question which is much more challenging, the report considered precursor events identified through a search and analysis of the IRS database and also precursors events based on risk significance. Both methods can point out areas where further work may be needed, even if it depends heavily on design and site-specific factors. From the operating experience side, more efforts are needed to ensure timely and full implementation of lessons learnt from precursor events. Concerning risk considerations, a combined use of risk precursors and operating experience may drive to effective changes to plants to reduce risk. The report also contains a short description and evaluation of selected precursors that are related to the course of the Fukushima Daiichi NPP accident. The report addresses the question whether operating experience feedback can be effectively used to identify plant vulnerabilities and minimize potential for severe core damage accidents. Based on several of the precursor events national or international in-depth evaluations were started. The vulnerability of NPPs due to external and internal flooding has clearly been addressed. In addition to the IRS based investigation, the WGRISK was asked to identify important precursor events based on risk significance. These precursors have

  15. Synthesis and characterization of CdS quantum dots stabilized with poly(vinyl alcohol): effect of molar fraction of precursors; Sintese e caracterizacao de pontos quanticos de CdS estabilizados com poli(alcool vinilico): efeito da fracao molar dos precursores

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-07-01

    Semiconductor nanoparticles (quantum dots) with size lower than Bohr radius present quantum confinement effect, and properties dependent on particle diameter. The use of these nanoparticles for biological applications is highly promising, however this kind of use requires biocompatible systems. In this sense, the choice of poly(vinyl alcohol), PVA, as stabilizing agent has been investigated. The main goal of this work was synthesize and characterize CdS nanoparticles using PVA as capping agent varying the molar ratio of cadmium and sulfur precursors. The results revealed that absorption and emission properties, as well as nanoparticle size, were function of Cd/S ratio. (author)

  16. Effect of regional precursor emission controls on long-range ozone transport – Part 1: Short-term changes in ozone air quality

    Directory of Open Access Journals (Sweden)

    J. J. West

    2009-08-01

    Full Text Available Observations and models demonstrate that ozone and its precursors can be transported between continents and across oceans. We model the influences of 10% reductions in anthropogenic nitrogen oxide (NOx emissions from each of nine world regions on surface ozone air quality in that region and all other regions. In doing so, we quantify the relative importance of long-range transport between all source-receptor pairs, for direct short-term ozone changes. We find that for population-weighted concentrations during the three-month "ozone-season", the strongest inter-regional influences are from Europe to the Former Soviet Union, East Asia to Southeast Asia, and Europe to Africa. The largest influences per unit of NOx reduced, however, are seen for source regions in the tropics and Southern Hemisphere, which we attribute mainly to greater sensitivity to changes in NOx in the lower troposphere, and secondarily to increased vertical convection to the free troposphere in tropical regions, allowing pollutants to be transported further. Results show, for example, that NOx reductions in North America are ~20% as effective per unit NOx in reducing ozone in Europe during summer, as NOx reductions from Europe itself. Reducing anthropogenic emissions of non-methane volatile organic compounds (NMVOCs and carbon monoxide (CO by 10% in selected regions, can have as large an impact on long-range ozone transport as NOx reductions, depending on the source region. We find that for many source-receptor pairs, the season of greatest long-range influence does not coincide with the season when ozone is highest in the receptor region. Reducing NOx emissions in most source regions causes a larger decrease in export of ozone from the source region than in ozone production outside of the source region.

  17. Effect of precursors stoichiometry on morphology, crystallinity and electrical properties of ZnTe epilayers grown on (100)GaAs by MOVPE

    International Nuclear Information System (INIS)

    Paiano, P.; Lovergine, N.; Mancini, A.M.; Prete, P.

    2005-01-01

    The effect of precursors vapour stoichiometry on the morphological, structural and electrical properties of nominally undoped ZnTe grown on (100)GaAs by metalorganic vapour phase epitaxy is reported. The epilayers were grown at 350 C using dimethylzinc (Me 2 Zn) and di-isopropyltelluride, varying their molar flow rate ratios (MFRs) between 0.17 and 3.10. Growth in nearly stoichiometric (MFR=1.03) conditions results in best surface morphology, while samples grown in Te-rich conditions (MFR>1.7) showed micron-size hollow defects (with surface densities up to ∝10 6 cm -2 ) elongated in one of the left angle 011 right angle in-plane directions. The defects are associated to a local structural disorder of the material, ascribed to the formation of a Ga 2 Te 3 extrinsic phase at the ZnTe/GaAs interface. Ohmic contacts to p -ZnTe epilayers were prepared by tungsten evaporation and annealing at 350 C. The RT hole concentration in the epilayers varies almost linearly with Me 2 Zn molar flow between 2 x 10 15 cm -3 and 5 x 10 16 cm -3 . Temperature-dependent Hall measurements performed on samples grown at MFR≤1.03 demonstrate that the material p-type conductivity originates from a single acceptor centre with an ionisation energy between 94.7 meV and 118 meV, its concentration being in the 10 16 cm -3 range and slowly increasing with Me 2 Zn flow. We ascribe this acceptor to a complex formed by a substitutional carbon atom on a Te site and a donor on a nearest neighbor site (C Te -D Zn ), the donor impurity being further identified as Ga diffusing from the substrate. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. Thermal-annealing effects on the structural and magnetic properties of 10% Fe-doped SnO{sub 2} nanoparticles synthetized by a polymer precursor method

    Energy Technology Data Exchange (ETDEWEB)

    Aragón, F.H., E-mail: fermin964@hotmail.com [Núcleo de Física Aplicada, Instituto de Física, Universidade de Brasília, Brasília DF 70910-900 (Brazil); Instituto de Ciências Biológicas, Pós-graduação em Nanociência e Nanobiotecnologia, Universidade de Brasília, Brasilia DF 70919-970 (Brazil); Coaquira, J.A.H. [Núcleo de Física Aplicada, Instituto de Física, Universidade de Brasília, Brasília DF 70910-900 (Brazil); Nagamine, L.C.C.M.; Cohen, R. [Instituto de Física, Universidade de São Paulo, São Paulo SP 05508-090 (Brazil); Silva, S.W. da [Núcleo de Física Aplicada, Instituto de Física, Universidade de Brasília, Brasília DF 70910-900 (Brazil); Instituto de Ciências Biológicas, Pós-graduação em Nanociência e Nanobiotecnologia, Universidade de Brasília, Brasilia DF 70919-970 (Brazil); and others

    2015-02-01

    In this work, we present the experimental results of Sn{sub 0.9}Fe{sub 0.1}O{sub 2} nanoparticles synthesized by a polymer precursor method. Studies were performed in the as-prepared (AP) and thermally-annealed (TA) samples. The X-ray diffraction (XRD) data analysis carried out using the Rietveld refinement method shows the formation of only the rutile-type structure in the AP sample and this phase remains stable for the TA sample. Additionally, the mean crystallite size shows an increase from ∼4 nm to ∼17 nm after the annealing and a clear reduction of the residual strain has also been determined. Micro-Raman spectroscopy measurements show the formation of an iron oxide phase (likely α-Fe{sub 2}O{sub 3}) after the thermal treatment. Magnetic measurements show a paramagnetic behavior for the AP sample and the coexistence of a weak ferromagnetism and paramagnetism for the TA sample. The magnetically-ordered contribution of the TA sample has been assigned to the formation of the hematite phase. DC and AC magnetic features of the TA sample are consistent with a cluster-glass behavior which seems to be related to the magnetic disorder of spins located at the particle surface. Those spins clusters seem to be formed due to the diffusion of iron ions from the core of the particle to the surface caused by the annealing process. - Highlights: • Thermal annealing effects in the 10% Fe-doped SnO{sub 2} nanoparticles have been studied. • XRD data analysis shows the formation of the rutile-type structure. • Raman measurements show the formation of small amount of α-Fe{sub 2}O{sub 3} after the annealing. • Paramagnetic and magnetically ordered phases were determined after the annealing. • Spin clusters likely at the particle surface have been formed after the annealing.

  19. OTX2 exhibits cell-context-dependent effects on cellular and molecular properties of human embryonic neural precursors and medulloblastoma cells

    Directory of Open Access Journals (Sweden)

    Ravinder Kaur

    2015-10-01

    Full Text Available Medulloblastoma (MB is the most common malignant primary pediatric brain tumor and is currently divided into four subtypes based on different genomic alterations, gene expression profiles and response to treatment: WNT, Sonic Hedgehog (SHH, Group 3 and Group 4. This extensive heterogeneity has made it difficult to assess the functional relevance of genes to malignant progression. For example, expression of the transcription factor Orthodenticle homeobox2 (OTX2 is frequently dysregulated in multiple MB variants; however, its role may be subtype specific. We recently demonstrated that neural precursors derived from transformed human embryonic stem cells (trans-hENs, but not their normal counterparts (hENs, resemble Groups 3 and 4 MB in vitro and in vivo. Here, we tested the utility of this model system as a means of dissecting the role of OTX2 in MB using gain- and loss-of-function studies in hENs and trans-hENs, respectively. Parallel experiments with MB cells revealed that OTX2 exerts inhibitory effects on hEN and SHH MB cells by regulating growth, self-renewal and migration in vitro and tumor growth in vivo. This was accompanied by decreased expression of pluripotent genes, such as SOX2, and was supported by overexpression of SOX2 in OTX2+ SHH MB and hENs that resulted in significant rescue of self-renewal and cell migration. By contrast, OTX2 is oncogenic and promotes self-renewal of trans-hENs and Groups 3 and 4 MB independent of pluripotent gene expression. Our results demonstrate a novel role for OTX2 in self-renewal and migration of hENs and MB cells and reveal a cell-context-dependent link between OTX2 and pluripotent genes. Our study underscores the value of human embryonic stem cell derivatives as alternatives to cell lines and heterogeneous patient samples for investigating the contribution of key developmental regulators to MB progression.

  20. Effects of Starting Precursor Ratio on Optoelectrical Properties and Blue Emission of Nanostructured C-ZnS Thin Films Prepared by Spin Coating

    Science.gov (United States)

    Rahimzadeh, N.; Ghodsi, F. E.; Mazloom, J.

    2018-02-01

    Nanocrystalline cubic zinc sulfide (C-ZnS) thin films have been elaborated by sol-gel spin-coating of Zn(Ac)/thiourea starting precursors at different molar ratios, and their structural, morphological, compositional, optical, electrical, and photoluminescence properties comprehensively investigated. x-ray diffraction results showed that the samples had dominant cubic structure and their crystallinity improved with increasing S content. Morphological characterization of the C-ZnS thin films was carried out by field-emission scanning electron microscopy (FESEM), revealing that the films were smooth with spherical grains included in clusters. Energy-dispersive x-ray and Fourier-transform infrared spectra of ZnS compounds did not show any evidence of impurities. Optical characterization revealed increases of the average optical transmittance and bandgap (from 3.2 eV to 3.56 eV) with increasing S content. The refractive index in the visible region increased with the S content, while the extinction coefficient decreased. The compositional dependence of the optical dispersion parameters (oscillator and dispersion energy), dielectric constant, and surface energy loss function of the films was evaluated. Electrical characterization of the films was carried out using Hall-effect measurements. The ZnS thin films exhibited n-type conductivity, and the electrical resistivity decreased with increasing carrier concentration and mobility due to enhanced crystallite size and reduced structural disorder. Photoluminescence (PL) measurements indicated a blue-shift of the near-band-edge emission. The blue emission peaks centered at about 438 nm and 487 nm were enhanced due to transitions involving interstitial S atoms, surface states, and zinc vacancies.

  1. Surface Induced Dissociations and Reactions of Acetonitrile Monomer, Dimer and Trimer Ions

    Czech Academy of Sciences Publication Activity Database

    Mair, C.; Herman, Zdeněk; Fedor, J.; Lezius, M.; Märk, T. D.

    2003-01-01

    Roč. 118, č. 3 (2003), s. 1479-1486 ISSN 0021-9606 R&D Projects: GA ČR GA203/00/0632 Grant - others:Cooperation PST(AT) 2000-06 Institutional research plan: CEZ:AV0Z4040901 Keywords : surface-induced * acetonitrile monomer * trimer ions Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.950, year: 2003

  2. The Effects of Annealing Parameters on the Crystallization and Morphology of Cu(In,GaSe2 Absorber Layers Prepared by Annealing Stacked Metallic Precursors

    Directory of Open Access Journals (Sweden)

    Chia-Ho Huang

    2014-01-01

    Full Text Available CIGS films are prepared by single-stage annealing of the solid Se-coated In/Cu-Ga bilayer precursor. The annealing processes were performed using various Ar pressures, heating rates, and soaking times. A higher Ar pressure is needed to fabricate highly crystalline CIGS films, as no extra Se-vapor source is supplied. As the heating rate increases, the surface morphologies of the CIGS films become looser and some cracks are observed. However, the influence of soaking time is insignificant and the selenization process only requires a short time when the precursors are selenized at a higher temperature with a lower heating rate and a higher Ar pressure. In this study, a dense chalcopyrite CIGS film with a thickness of about 1.5-1.6 μm, with large grains (~1.2 μm and no cracking or peeling is obtained after selenizing at a temperature of 550°C, an Ar pressure of 300 Torr, a heating rate of 60°C/min, and a soaking time of 20 min. By adequate design of the stacked precursor and controlling the annealing parameters, single-stage annealing of the solid Se-coated In/Cu-Ga bilayer precursor is simplified for the fabrication of a fully crystallized chalcopyrite CIGS absorber layers with good crystallization and large grains.

  3. Alternative group V precursors for CVD applications

    Science.gov (United States)

    Lum, R. M.; Klingert, J. K.

    1991-01-01

    The chemical vapor deposition (CVD) techniques used to grow III/V semiconductors films, such as metalorganic vapor phase epitaxy (MOVPE), hydride VPE, chemical beam epitaxy (CBE) and gas source molecular beam epitaxy (GS-MBE), all use hydrides (AsH 3 and PH 3) as the Group V source. However, the hydrides are extremely toxic gases which are stored under high pressure (200-2000 psi). To reduce the safety hazards associated with these gases, alternative Group V precursors have been investigated. Organoarsenic and phosphorous compounds have received the most attention as replacements for AsH 3 and PH 3 because they are typically low vapor pressure liquids, and thus present significantly lower exposure risks than the hydrides. For AsH 3 these have included the methyl, ethyl and butyl-based derivatives RnAsH 3- n, with varying degrees ( n = 1-3) of hydrogen atom substitution. In this paper the growth properties, thermochemistry and toxicity of the various alkylarsine precursors are compared with arsine. Data are presented on the impact of the thermochemistry of these compounds on film electrical properties, and on the effects of precursor composition and purity on overall film quality. The suitability of alternative As-precursors for device applications is demonstrated, and selection criteria are presented for the most effective alkylarsine compound for a particular CVD growth process.

  4. Effects of curcumin and demethoxycurcumin on amyloid-β precursor and tau proteins through the internal ribosome entry sites: a potential therapeutic for Alzheimer's disease.

    Science.gov (United States)

    Villaflores, Oliver B; Chen, Ying-Ju; Chen, Chih-Ping; Yeh, Jui-Ming; Wu, Tzong-Yuan

    2012-12-01

    This study aims to determine the effects of curcumin and demethoxycurcumin on the internal ribosome entry site of the amyloid-β precursor protein (APP) and tau protein through a bi-cistronic reporter assay for screening of anti-Alzheimer's disease agents. A bi-cistronic assay was performed wherein the expression of the first cistron, a β-galactosidase gene under the control of a cytomegalovirus promoter, represents the canonical cap-dependent mechanism of translation initiation; while the second cistron involves the utilization of the APP or the tau IRES elements to drive the expression of secreted alkaline phosphatase (SEAP) under a cap-independent mechanism. Bioactive natural products reported to have therapeutic potential for AD such as curcumin and demethoxycurcumin were screened in an murine neuroblastoma (N2A) cell model. Western blot analyses for the expression of APP C-terminal protein, human tau-1, and phosphorylated tau at Serine 262 (p(262)) and Serine 396 (pS(396)) were done after treatment of N2A cells with the test compounds. The bi-cistronic reporter assay revealed that curcumin was more effective than demethoxycurcumin, a structural analog of curcumin, in inhibiting both APP and tau IRES-dependent translation initiation. This result was further confirmed by Western blot analysis for the expression of APP C-terminal protein, human tau-1, pS(262) and pS(396) suggesting that curcumin may play a role in AD pathology alleviation through the inhibition of the APP and tau IRES-mediated translation mechanism. On the other hand, demethoxycurcumin was observed to inhibit the phosphorylation of both tau pS(262) and pS(396). A novel assay system using the bi-cistronic reporter constructs for the identification of compounds with activity against the translation directed by APP and tau IRES was developed. The results provide novel suggestive insights for the potential use of the mentioned compounds as prophylactic and therapeutic anti-AD agents. Copyright

  5. Effect of an hyperbaric nitrogen narcotic ambience on arginine and citrulline levels, the precursor and co-product of nitric oxide, in rat striatum

    Directory of Open Access Journals (Sweden)

    Vallée Nicolas

    2011-07-01

    Full Text Available Abstract Previous studies performed in the laboratory have shown that nitrogen narcosis induces a decrease in striatal glutamate and dopamine levels. Although we stimulated the N-methyl-D-aspartate (NMDA receptor, an important glutamate receptor required for motor and locomotor activity managed by the striatum, and demonstrated that the receptor was effective when exposed to nitrogen at 3MPa, it was not possible to return the striatal glutamate level to its base values. We conclude that it was the striatopetal neurons of the glutamatergic pathways that were mainly affected in this hyperbaric syndrome, without understanding the principal reasons. Hence we sought to establish what happens in the vicinity of the plasma membrane, downstream the NMDA-Receptor, and we used the hypothesis that there could be neuronal nitric oxide synthase (nNOS disturbances. A microdialysis study was performed in rat striatum in order to analyse levels of citrulline, the NO co-product, and arginine, the NO precursor. Those both NO metabolites were detectable with an HPLC coupled to a fluorimetric detector. Exposure to pressurized nitrogen induced a reduction in citrulline (-18.9% and arginine (-10.4% levels. Under the control normobaric conditions, the striatal NMDA infusion enhanced the citrulline level (+85.6%, whereas under 3 MPa of nitrogen, the same NMDA infusion did not change the citrulline level which remains equivalent to that of the baseline. The level of arginine increased (+45.7% under normobaric conditions but a decrease occurred in pressurized nitrogen (-51.6%. Retrodialysis with Saclofen and KCl in the prefrontal cortex under normobaric conditions led to an increase in striatal levels of citrulline (+30.5% and a decrease in arginine levels (-67.4%. There was no significant difference when nitrogen at 3MPa was added. To conclude, the synthesis of citrulline/NO is reduced in nitrogen narcosis while it seems possible to activate it artificially by infusion

  6. Effect of an hyperbaric nitrogen narcotic ambience on arginine and citrulline levels, the precursor and co-product of nitric oxide, in rat striatum

    Science.gov (United States)

    2011-01-01

    Previous studies performed in the laboratory have shown that nitrogen narcosis induces a decrease in striatal glutamate and dopamine levels. Although we stimulated the N-methyl-D-aspartate (NMDA) receptor, an important glutamate receptor required for motor and locomotor activity managed by the striatum, and demonstrated that the receptor was effective when exposed to nitrogen at 3MPa, it was not possible to return the striatal glutamate level to its base values. We conclude that it was the striatopetal neurons of the glutamatergic pathways that were mainly affected in this hyperbaric syndrome, without understanding the principal reasons. Hence we sought to establish what happens in the vicinity of the plasma membrane, downstream the NMDA-Receptor, and we used the hypothesis that there could be neuronal nitric oxide synthase (nNOS) disturbances. A microdialysis study was performed in rat striatum in order to analyse levels of citrulline, the NO co-product, and arginine, the NO precursor. Those both NO metabolites were detectable with an HPLC coupled to a fluorimetric detector. Exposure to pressurized nitrogen induced a reduction in citrulline (-18.9%) and arginine (-10.4%) levels. Under the control normobaric conditions, the striatal NMDA infusion enhanced the citrulline level (+85.6%), whereas under 3 MPa of nitrogen, the same NMDA infusion did not change the citrulline level which remains equivalent to that of the baseline. The level of arginine increased (+45.7%) under normobaric conditions but a decrease occurred in pressurized nitrogen (-51.6%). Retrodialysis with Saclofen and KCl in the prefrontal cortex under normobaric conditions led to an increase in striatal levels of citrulline (+30.5%) and a decrease in arginine levels (-67.4%). There was no significant difference when nitrogen at 3MPa was added. To conclude, the synthesis of citrulline/NO is reduced in nitrogen narcosis while it seems possible to activate it artificially by infusion. We have suggested

  7. Effect of precursors stoichiometry on morphology, crystallinity and electrical properties of ZnTe epilayers grown on (100)GaAs by MOVPE

    Energy Technology Data Exchange (ETDEWEB)

    Paiano, P.; Lovergine, N.; Mancini, A.M. [Dipartimento di Ingegneria dell' Innovazione, Universita di Lecce, Via Arnesano, I-73100 Lecce (Italy); Prete, P. [Istituto per la Microelettronica e Microsistemi del CNR, Sezione di Lecce, Via Arnesano, I-73100 Lecce (Italy)

    2005-11-01

    The effect of precursors vapour stoichiometry on the morphological, structural and electrical properties of nominally undoped ZnTe grown on (100)GaAs by metalorganic vapour phase epitaxy is reported. The epilayers were grown at 350 C using dimethylzinc (Me{sub 2}Zn) and di-isopropyltelluride, varying their molar flow rate ratios (MFRs) between 0.17 and 3.10. Growth in nearly stoichiometric (MFR=1.03) conditions results in best surface morphology, while samples grown in Te-rich conditions (MFR>1.7) showed micron-size hollow defects (with surface densities up to {proportional_to}10{sup 6} cm{sup -2}) elongated in one of the left angle 011 right angle in-plane directions. The defects are associated to a local structural disorder of the material, ascribed to the formation of a Ga{sub 2}Te{sub 3} extrinsic phase at the ZnTe/GaAs interface. Ohmic contacts to p -ZnTe epilayers were prepared by tungsten evaporation and annealing at 350 C. The RT hole concentration in the epilayers varies almost linearly with Me{sub 2}Zn molar flow between 2 x 10{sup 15} cm{sup -3} and 5 x 10{sup 16} cm{sup -3}. Temperature-dependent Hall measurements performed on samples grown at MFR{<=}1.03 demonstrate that the material p-type conductivity originates from a single acceptor centre with an ionisation energy between 94.7 meV and 118 meV, its concentration being in the 10{sup 16} cm{sup -3} range and slowly increasing with Me{sub 2}Zn flow. We ascribe this acceptor to a complex formed by a substitutional carbon atom on a Te site and a donor on a nearest neighbor site (C{sub Te}-D{sub Zn}), the donor impurity being further identified as Ga diffusing from the substrate. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. The effect of ALD-Zno layers on the formation of CH₃NH₃PbI₃ with different perovskite precursors and sintering temperatures.

    Science.gov (United States)

    Dong, Xu; Hu, Hongwei; Lin, Bencai; Ding, Jianning; Yuan, Ningyi

    2014-11-28

    ZnO films deposited by atomic layer deposition at 70 °C were used to fabricate perovskite solar cells, and a conversion efficiency of 13.1% was obtained. On the ZnO layer, CH3NH3PbI3 was formed at room temperature using CH3NH3I and PbCl2 precursors, which is in contrast to the reported results.

  9. The Effects of Repeated Low-Level Sarin Exposure on Muscarinic M1 Receptor Binding, Amyloid Precursor Protein Levels and Neuropathology

    Science.gov (United States)

    2005-08-01

    acetylcholinesterase (AChE) and the subsequent accumulation of synaptic acetylcholine (ACh). Likewise, exposure to the potent cholinergic agonist BM 123...Rev. 1997; 21(5): 559-579. 25. Muller DM, Mendla K, Farber SA and Nitsch RM. Muscarinic M1 receptor agonists increase the secretion of the amyloid...precursor protein ectodomain. Life Sciences. 1997; 60:985-991. 26. Nitsch RM, Deng M, Growdon JH and Wurtman RJ. Serotonin 5- HT2a and 5-HT2c

  10. Effect of different sulphur precursors on morphology and band-gap on the formation of Cu{sub 2}ZnSnS{sub 4} (CZTS) particles with microwave irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Patro, Bharati; Vijaylakshmi, S., E-mail: vlakshmi@iitb.ac.in [Centre for Research in Nanotechnology and Sciences, Indian Institute of Technology Bombay (India); Sharma, Pratibha [Department of Energy Sciences and Engineering, Indian Institute of Technology Bombay (India)

    2016-05-23

    Cu{sub 2}ZnSnS{sub 4} (CZTS) is a promising semiconductor material for ecological cost effective thin film Photovoltaic (PV) devices. As it contains earth abundant and non-toxic elements, it has the advantages over commercially available CIGS and CdTe thin film PV devices. In the present work, the pure phase Cu{sub 2}ZnSnS{sub 4} particles were successfully synthesised with microwave irradiation. The morphology and phase study was carried out for the samples prepared with two different sulphur precursors viz. thiourea and thioacetamide (TAA). CZTS particles with thiourea as sulphur precursor are more crystalline than CZTS particles with TAA. The band gap of 1.654 eV and 1.713 eV were calculated for the samples prepared with thiourea and TAA respectively.

  11. Effect of precursor solutions stirring on deep level defects concentration and spatial distribution in low temperature aqueous chemical synthesis of zinc oxide nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Alnoor, Hatim, E-mail: hatim.alnoor@liu.se; Chey, Chan Oeurn; Pozina, Galia; Willander, Magnus; Nur, Omer [Department of Science and Technology (ITN), Campus Norrköping, Linköping University, SE-601 74 Norrköping (Sweden); Liu, Xianjie; Khranovskyy, Volodymyr [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-583 81 Linköping (Sweden)

    2015-08-15

    Hexagonal c-axis oriented zinc oxide (ZnO) nanorods (NRs) with 120-300 nm diameters are synthesized via the low temperature aqueous chemical route at 80 °C on silver-coated glass substrates. The influence of varying the precursor solutions stirring durations on the concentration and spatial distributions of deep level defects in ZnO NRs is investigated. Room temperature micro-photoluminesnce (μ-PL) spectra were collected for all samples. Cathodoluminescence (CL) spectra of the as-synthesized NRs reveal a significant change in the intensity ratio of the near band edge emission (NBE) to the deep-level emission (DLE) peaks with increasing stirring durations. This is attributed to the variation in the concentration of the oxygen-deficiency with increasing stirring durations as suggested from the X-ray photoelectron spectroscopy analysis. Spatially resolved CL spectra taken along individual NRs revealed that stirring the precursor solutions for relatively short duration (1-3 h), which likely induced high super saturation under thermodynamic equilibrium during the synthesis process, is observed to favor the formation of point defects moving towards the tip of the NRs. In contrary, stirring for longer duration (5-15 h) will induce low super saturation favoring the formation of point defects located at the bottom of the NRs. These findings demonstrate that it is possible to control the concentration and spatial distribution of deep level defects in ZnO NRs by varying the stirring durations of the precursor solutions.

  12. Surface induced ordering of micelles at the solid-liquid interface

    DEFF Research Database (Denmark)

    Gerstenberg, M.C.; Pedersen, J.S.; Smith, G.S.

    1998-01-01

    The surface induced ordering of triblock copolymer micelles in aqueous solution was measured with neutron reflectivity far above the critical micelle concentration. The scattering length density profiles showed a clear indication of ordered layers of micelles perpendicular to a quartz surface....... The structure and interactions of the micelles were modeled in detail. The convolution of the center distribution of the micelles, obtained from Monte Carlo simulations of hard spheres at a hard wall, and the projected density of the micelle showed excellent agreement with the experimental profiles. [S1063-651X...

  13. Effect of Huannao Yicong prescription [See Text] extract on β-amyloid precursor protein metabolic signal transduction-related protein in brain tissue of dementia model transgenic mouse.

    Science.gov (United States)

    Li, Hao; Liu, Ming-Fang; Liu, Jian-Gang; Liu, Long-Tao; Guan, Jie; Cai, Lin-Lin; Hu, Jia; Wei, Yun

    2012-09-01

    To observe the effect of Huannao Yicong Prescription (, HNYC, a Chinese medical compound) extract on β-amyloid precursor protein (APP) metabolic signal transduction related protein kinase C (PKC), tyrosine amyloid protein kinase (TrKA), and glycogen synthase kinase-3 (GSK-3) in brain tissue of transgenic mouse dementia model induced by APP. Sixty dementia model transgenic 3-month-old mice induced by APP695V717I were randomly allocated in four groups: the model group (A), the Donepezil (0.65×10(-3) g·kg(-1)·(-1))-treated group (B), and the two HNYC-treated groups (C and D) with high dosage (2.8 g·kg(-1)·(-1)) and low dosage (1.4 g·kg(-1)·(-1)) of HNYC extract, respectively, 15 mice in each group. Besides, a normal control group was set up with 15 C57BL/6J mice with the same age and genetic background as the model mice. The drugs for treatment were administered once a day by dissolving in equal-volume distilled water through gastric infusion, continued for 6 months, to mice in group A and to normal control group equal-volume distilled water was administered instead. Spatial learning and memory capacity of mice were observed by Morris water maze; their one-time escape response memory capacity was tested by diving platform; and changes of PKC, TrkA, and GSK-3 levels in hippocampus and cortex of brain were detected by Western blotting. HNYC extract showed significant effects on increasing the time of model mice for swimming through the flat roof and the swimming time and path in the fourth quadrant P<0.05 or P<0.01). Diving platform test showed that the latent times in Groups B and C were longer than that in Group A significantly (P <0.05 and P<0.01). Compared with the normal control group, PKC and TrkA protein expression levels in hippocampus and cortex of model mice's brain lowered significantly (P<0.01), while GSK-3 protein expression increased significantly (P<0.01); compared with Group A (the model group), hippocampal and cortical levels of PKC protein

  14. Effect of precursor solutions stirring on deep level defects concentration and spatial distribution in low temperature aqueous chemical synthesis of zinc oxide nanorods

    Directory of Open Access Journals (Sweden)

    Hatim Alnoor

    2015-08-01

    Full Text Available Hexagonal c-axis oriented zinc oxide (ZnO nanorods (NRs with 120-300 nm diameters are synthesized via the low temperature aqueous chemical route at 80 °C on silver-coated glass substrates. The influence of varying the precursor solutions stirring durations on the concentration and spatial distributions of deep level defects in ZnO NRs is investigated. Room temperature micro-photoluminesnce (μ-PL spectra were collected for all samples. Cathodoluminescence (CL spectra of the as-synthesized NRs reveal a significant change in the intensity ratio of the near band edge emission (NBE to the deep-level emission (DLE peaks with increasing stirring durations. This is attributed to the variation in the concentration of the oxygen-deficiency with increasing stirring durations as suggested from the X-ray photoelectron spectroscopy analysis. Spatially resolved CL spectra taken along individual NRs revealed that stirring the precursor solutions for relatively short duration (1-3 h, which likely induced high super saturation under thermodynamic equilibrium during the synthesis process, is observed to favor the formation of point defects moving towards the tip of the NRs. In contrary, stirring for longer duration (5-15 h will induce low super saturation favoring the formation of point defects located at the bottom of the NRs. These findings demonstrate that it is possible to control the concentration and spatial distribution of deep level defects in ZnO NRs by varying the stirring durations of the precursor solutions.

  15. Effects of precursor concentrations on the optical and morphological properties of ZnO nanorods on glass substrate for UV photodetector

    Science.gov (United States)

    Abuelsamen, A. A.; Mahmud, Shahrom; Seeni, Azman; Kaus, Noor Haida Mohd; Farhat, O. F.

    2017-11-01

    In this study, zinc oxide (ZnO) nanorod arrays with various precursor concentrations (0.05, 0.10 and 0.15 M) were synthesized using a simple hydrothermal reaction on ZnO seeds/glass substrate and tested for UV-photodetector. The structural and optical properties of the ZnO nanorods have been investigated. The results demonstrate that morphology and crystallinity of ZnO nanorods influenced by the concentration of the precursor and had a high impact on the UV-photosensing. As the precursor concentration increased by 0.1 M, the density and the surface-to-volume ratio of ZnO nanorods decreased by 49 nanorods per μm2 and 22.9 respectively. At the lowest concentration of 0.05 M, the ZnO nanorods grew with high density of 85 nanorod per μm2 and high surface-to-volume ratio of 28.5. Moreover, a strong ultraviolet (UV) emission peak (λ = 375 nm) was observed with a low deep-level emission peak (λ = 580 nm), which indicated high optical property and crystallinity of the nanorods. The synthesized ZnO nanorods exhibited different sensing characteristics that correlated with the morphological and structure of ZnO nanorods formed at different concentrations. The sample grew with concentration of 0.05 M showed the highest photocurrent of 1.949 × 10-4 A and current gain of 562.1 under low power intensity UV illumination at λ = 375 nm with 5 V bias.

  16. Precursor composites for oxygen dispersion hardened silver sheathed superconductor composites

    Science.gov (United States)

    Podtburg, Eric R.

    1999-01-01

    An oxide superconductor composite having improved texture and durability. The oxide superconductor composite includes an oxide superconductor phase substantially surrounded with/by a noble metal matrix, the noble metal matrix comprising a metal oxide in an amount effective to form metal oxide domains that increase hardness of the composite. The composite is characterized by a degree of texture at least 10% greater than a comparable oxide superconductor composite lacking metal oxide domains. An oxide superconducting composite may be prepared by oxidizing the precursor composite under conditions effective to form solute metal oxide domains within the silver matrix and to form a precursor oxide in the precursor alloy phase; subjecting the oxidized composite to a softening anneal under conditions effective to relieve stress within the noble metal phase; and converting the oxide precursor into an oxide superconductor.

  17. Synthesis, structural, morphological, optical and magnetic characterization of iron oxide (α-Fe2O3) nanoparticles by precipitation method: Effect of varying the nature of precursor

    Science.gov (United States)

    Lassoued, Abdelmajid; Lassoued, Mohamed Saber; Dkhil, Brahim; Ammar, Salah; Gadri, Abdellatif

    2018-03-01

    α-Fe2O3 nanoparticles were prepared via a precipitation method using each of three different precursors ((FeCl3, 6H2O), (Fe (C5H7O2)3) and (Fe (NO3)3, 9H2O)). The impact of varying the nature of the precursor on crystalline phase, size and magnetic parameters of α-Fe2O3 was examined. Powder X-ray diffraction pattern disclosed rhombohedral structure. The TEM and SEM results showed that the size of α-Fe2O3 nanocrystals was between 21 and 38 nm. FT-IR confirms the phase purity of prepared compounds. Raman studies showed the phonon modes. The TGA showed three mass losses, whereas DTA resulted in three endothermic peaks. The optical investigation exhibited that samples have an optical gap of 2.1 eV. The products exhibited the attractive magnetic properties with high saturation magnetization, which were examined by a vibrating sample magnetometer (VSM).

  18. The Effect of Pro-Neurogenic Gene Expression on Adult Subventricular Zone Precursor Cell Recruitment and Fate Determination After Excitotoxic Brain Injury

    Directory of Open Access Journals (Sweden)

    Jones KS

    2016-05-01

    Full Text Available Despite the presence of on-going neurogenesis in the adult mammalian brain, neurons are generally not replaced after injury. Using a rodent model of excitotoxic cell loss and retroviral (RV lineage tracing, we previously demonstrated transient recruitment of precursor cells from the subventricular zone (SVZ into the lesioned striatum. In the current study we determined that these cells included migratory neuroblasts and oligodendrocyte precursor cells (OPC, with the predominant response from glial cells. We attempted to override this glial response by ectopic expression of the pro-neurogenic genes Pax6 or Dlx2 in the adult rat SVZ following quinolinic acid lesioning. RV-Dlx2 over-expression stimulated repair at a previously non-neurogenic time point by enhancing neuroblast recruitment and the percentage of cells that retained a neuronal fate within the lesioned area, compared to RV-GFP controls. RV-Pax6 expression was unsuccessful at inhibiting glial fate and intriguingly, increased OPC cell numbers with no change in neuronal recruitment. These findings suggest that gene choice is important when attempting to augment endogenous repair as the lesioned environment can overcome pro-neurogenic gene expression. Dlx2 over-expression however was able to partially overcome an anti-neuronal environment and therefore is a promising candidate for further study of striatal regeneration.

  19. Effects of precursor on the morphology and size of ZrO2 nanoparticles, synthesized by sol-gel method in non-aqueous medium

    Directory of Open Access Journals (Sweden)

    Mohammed Rafiq Hussain Siddiqui

    2012-12-01

    Full Text Available Pure zirconium oxide (ZrO2 nanoparticles with diameters 10-25 nm were synthesized from ZrOCl2.8H2O and Zr(SO42.H2O with benzyl alcohol as non-aqueous solvent medium using sol-gel method. Sodium lauryl sulfate was added as surfactants to control the particle size. The synthesized ZrO2 nanoparticles have a mixture of tetragonal and monoclinic structure. The XRD showed the purity of obtained ZrO2 nanoparticles with tetragonal and monoclinic phase and the crystallite size for ZrOCl2.8H2O precursor was estimated to be 18.1 nm and that from Zr(SO42.H2O was 9.7 nm. The transmission electron microscopy and scanning electron microscopic studies also shows different sizes of nanoparticles and different morphology depending on the precursor used for the synthesis of ZrO2 nanoparticles

  20. Effects of precursor on the morphology and size of ZrO{sub 2} nanoparticles, synthesized by sol-gel method in non-aqueous medium

    Energy Technology Data Exchange (ETDEWEB)

    Siddiqui, Mohammed Rafiq Hussain; Al-Wassil, Abdulaziz Ibrahim; Mahfouz, Refaat Mohamad [King Saud University, Riyadh (Saudi Arabia). Department of Chemistry, College of Science; Al-Otaibi, Abdullah Mohmmed [King Abdulaziz City for Science and Technology (Saudi Arabia). The NationalProgram for Advanced Materials and Building Systems

    2012-11-15

    Pure zirconium oxide (ZrO{sub 2}) nanoparticles with diameters 10-25 nm were synthesized from ZrOCl{sub 2}.8H{sub 2}O and Zr(SO{sub 4})2.H{sub 2}O with benzyl alcohol as non-aqueous solvent medium using sol-gel method. Sodium lauryl sulfate was added as surfactants to control the particle size. The synthesized ZrO{sub 2} nanoparticles have a mixture of tetragonal and monoclinic structure. The XRD showed the purity of obtained ZrO{sub 2} nanoparticles with tetragonal and monoclinic phase and the crystallite size for ZrOCl{sub 2}.8H{sub 2}O precursor was estimated to be 18.1 nm and that from Zr(SO{sub 4})2.H{sub 2}O was 9.7 nm. The transmission electron microscopy and scanning electron microscopic studies also shows different sizes of nanoparticles and different morphology depending on the precursor used for the synthesis of ZrO{sub 2} nanoparticles. (author)

  1. Preparation of superconductor precursor powders

    Science.gov (United States)

    Bhattacharya, Raghunath; Blaugher, Richard D.

    1995-01-01

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

  2. Trending analysis of precursor events

    International Nuclear Information System (INIS)

    Watanabe, Norio

    1998-01-01

    The Accident Sequence Precursor (ASP) Program of United States Nuclear Regulatory Commission (U.S.NRC) identifies and categorizes operational events at nuclear power plants in terms of the potential for core damage. The ASP analysis has been performed on yearly basis and the results have been published in the annual reports. This paper describes the trends in initiating events and dominant sequences for 459 precursors identified in the ASP Program during the 1969-94 period and also discusses a comparison with dominant sequences predicted in the past Probabilistic Risk Assessment (PRA) studies. These trends were examined for three time periods, 1969-81, 1984-87 and 1988-94. Although the different models had been used in the ASP analyses for these three periods, the distribution of precursors by dominant sequences show similar trends to each other. For example, the sequences involving loss of both main and auxiliary feedwater were identified in many PWR events and those involving loss of both high and low coolant injection were found in many BWR events. Also, it was found that these dominant sequences were comparable to those determined to be dominant in the predictions by the past PRAs. As well, a list of the 459 precursors identified are provided in Appendix, indicating initiating event types, unavailable systems, dominant sequences, conditional core damage probabilities, and so on. (author)

  3. Synthesis of labelled ecdysone precursors

    International Nuclear Information System (INIS)

    Haag, T.; Hetru, C.; Nakatani, Y.; Luu, B.; Meister, M.; Pichat, L.; Audinot, M.

    1985-01-01

    High specific activity tritiated 3β,14α-dihydroxy-5β-cholest-7-en-6-one, has been prepared using a precursor which permits rapid and easy labelling. This compound is converted to ecdysone under in vitro conditions by insect prothoracic glands, a well known site of ecdysone biosynthesis. (author)

  4. Interstellar shock waves with magnetic precursors

    International Nuclear Information System (INIS)

    Draine, B.T.

    1980-01-01

    The structure of steady, radiative, one-dimensional shock waves in partially ionized gas with a transverse magnetic field B 0 is investigated. Under a broad range of conditions applicable to the interstellar medium it is found that such shocks may be preceded by a magnetic precursor which heats and compresses the medium ahead of the front where the neutral gas undergoes a discontinuous change of state; indeed, if B 0 is sufficiently large, a shock can exist with no discontinuities in hydrodynamical variables. Within this magnetic precursor both ions and electrons stream through the neutral fluid with velocities which may be a significant fraction of the shock speed. The physical processes operative in such shocks are examined, including the effects of charged dust grains in dense molecular clouds. Numerical examples are shown for v/sub s/ = 10 km s -1 shocks propagating into diffuse H I or H 2 . Shocks with magnetic precursors may have important consequences for the interstellar medium, some of which are briefly considered

  5. Functionalization of Phenyl Rings by Imidoylnitrenes. 3 The Effects of Resonance, Steric, and Inductive Properties on the Reactivity or Selectivity of Nitrenes and the Stability of their Precursors

    Directory of Open Access Journals (Sweden)

    Reza Karimzadeh

    2002-02-01

    Full Text Available The thermal decomposition of imidoyl azides (ArO-C=N-Z-N3, (Ar = p-NO2-C6H4-, p-Br-C6H4-, p-Cl-C6H4-, p-C6H5-, p-CH3-C6H4-, 2,4-dimethyl-C6H3-, 2,4,6-trimethyl-C6H2-, p-CH3O-C6H4- and Z = p-CH3-C6H4-SO2-, 2,4,6-trimethyl-C6H2-SO2-,CN in the solid phase and in anisole has been studied in detail. The sensitivity of nitrenes and nitrene precursors (imidoyl azides towards substitution changes in the aryloxy (ArO and Z moieties is examined.

  6. Effect of chloride ions on anthrasesamone C production in a Sesamum indicum hairy root culture and identification of the precursor for its abiotic formation.

    Science.gov (United States)

    Furumoto, Toshio; Hoshikuma, Arata

    2012-01-01

    The content of anthrasesamone C (5), a rare chlorine-containing anthraquinone, in a hairy root culture of Sesamum indicum increased with increasing chloride ion concentration in the culture medium and reached a maximum at 100 mM. However, the amount of anthrasesamone C (5) in the extract obtained from the hairy roots was increased by incubating the extract. This result suggests that anthrasesamone C (5) was produced from an unidentified metabolite by an abiotic process. 2,3-Epoxyanthrasesamone B (1), a precursor for the non-enzymatic formation of anthrasesamone C (5), was isolated from S. indicum hairy roots cultured in a chloride-deficient medium. Its structure was elucidated to be 2,3-epoxy-9,10-dihydroxy-2-(4-methylpent-3-en-1-yl)-2,3-dihydroanthracene-1,4-dione by spectroscopic methods.

  7. Positioning of the Precursor Gas Inlet in an Atmospheric Dielectric Barrier Reactor, and its Effect on the Quality of Deposited TiOx Thin Film Surface

    Directory of Open Access Journals (Sweden)

    Jan Píchal

    2013-01-01

    Full Text Available Thin film technology has become pervasive in many applications in recent years, but it remains difficult to select the best deposition technique. A further consideration is that, due to ecological demands, we are forced to search for environmentally benign methods. One such method might be the application of cold plasmas, and there has already been a rapid growth in studies of cold plasma techniques. Plasma technologies operating at atmospheric pressure have been attracting increasing attention. The easiest way to obtain low temperature plasma at atmospheric pressure seems to be through atmospheric dielectric barrier discharge (ADBD. We used the plasma enhanced chemical vapour deposition (PECVD method applying atmospheric dielectric barrier discharge (ADBD plasmafor TiOx thin films deposition, employing titanium isopropoxide (TTIP and oxygen as reactants, and argon as a working gas. ADBD was operated in filamentary mode. The films were deposited on glass. We studied the quality of the deposited TiOx thin film surface for various precursor gas inlet positions in the ADBD reactor. The best thin films quality was achieved when the precursor gases were brought close to the substrate surface directly through the inlet placed in one of the electrodes.High hydrophilicity of the samples was proved by contact angle tests (CA. The film morphology was tested by atomic force microscopy (AFM. The thickness of the thin films varied in the range of (80 ÷ 210 nm in dependence on the composition of the reactor atmosphere. XPS analyses indicate that composition of the films is more like the composition of TiOxCy.

  8. Effect of precursor and preparation method on manganese based activated carbon sorbents for removing H2S from hot coal gas.

    Science.gov (United States)

    Wang, Jiancheng; Qiu, Biao; Han, Lina; Feng, Gang; Hu, Yongfeng; Chang, Liping; Bao, Weiren

    2012-04-30

    Activated carbon (AC) supported manganese oxide sorbents were prepared by the supercritical water impregnation (SCWI) using two different precursor of Mn(NO(3))(2) (SCW(N)) and Mn(Ac)(2)·4H(2)O (SCW(A)). Their capacities of removing H(2)S from coal gas were evaluated and compared to the sorbents prepared by the pore volume impregnation (PVI) method. The structure and composition of different sorbents were characterized by XRD, SEM, TEM, XPS and XANES techniques. It is found that the precursor of active component plays the crucial role and SCW(N) sorbents show much better sulfidation performance than the SCW(A) sorbents. This is because the Mn(3)O(4) active phase of the SCW(N) sorbents are well dispersed on the AC support, while the Mn(2)SiO(4)-like species in the SCW(A) sorbent can be formed and seriously aggregated. The SCW(N) sorbents with 2.80% and 5.60% manganese are favorable for the sulfidation reaction, since the Mn species are better dispersed on the SCW(N) sorbents than those on the PV(N) sorbents and results in the better sulfidation performance of the SCW(N) sorbents. As the Mn content increases to 11.20%, the metal oxide particles on AC supports aggregate seriously, which leads to poorer sulfidation performance of the SCW(N)11.20% sorbents than that of the PV(N)11.20% sorbents. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. Surface induces different crystal structures in a room temperature switchable spin crossover compound.

    Science.gov (United States)

    Gentili, Denis; Liscio, Fabiola; Demitri, Nicola; Schäfer, Bernhard; Borgatti, Francesco; Torelli, Piero; Gobaut, Benoit; Panaccione, Giancarlo; Rossi, Giorgio; Degli Esposti, Alessandra; Gazzano, Massimo; Milita, Silvia; Bergenti, Ilaria; Ruani, Giampiero; Šalitroš, Ivan; Ruben, Mario; Cavallini, Massimiliano

    2016-01-07

    We investigated the influence of surfaces in the formation of different crystal structures of a spin crossover compound, namely [Fe(L)2] (LH: (2-(pyrazol-1-yl)-6-(1H-tetrazol-5-yl)pyridine), which is a neutral compound thermally switchable around room temperature. We observed that the surface induces the formation of two different crystal structures, which exhibit opposite spin transitions, i.e. on heating them up to the transition temperature, one polymorph switches from high spin to low spin and the second polymorph switches irreversibly from low spin to high spin. We attributed this inversion to the presence of water molecules H-bonded to the complex tetrazolyl moieties in the crystals. Thin deposits were investigated by means of polarized optical microscopy, atomic force microscopy, X-ray diffraction, X-ray absorption spectroscopy and micro Raman spectroscopy; moreover the analysis of the Raman spectra and the interpretation of spin inversion were supported by DFT calculations.

  10. Optimization of precursor powders for manufacturing Bi-2223/Ag tapes

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, C H [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang (China); Yoo, J M [Materials Engineering Department, Korea Institute of Machinery and Materials, 66 Sangnam-Dong, Changwon (Korea, Republic of); Ko, J W [Materials Engineering Department, Korea Institute of Machinery and Materials, 66 Sangnam-Dong, Changwon (Korea, Republic of); Chung, H S [Department of Molecular Science and Technology, Ajou University (Korea, Republic of); Qiao, G W [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang (China)

    2003-01-01

    The phase assemblage and particle sizes of precursor powders have been optimized in a sequence for fabricating Ag/BSCCO-2223 composite tapes. Firstly, an optimal calcination temperature was determined based on the experimental results. Then, the precursors calcined at the optimal temperature were ball-milled for different dwell times to obtain varied particle sizes. The effects of both the phase assemblages and particle sizes of the precursor powder on the phase formation, microstructure and transport J{sub c} of Bi-2223/Ag tapes have been investigated. The results show that the precursor phase assemblage has a large impact on the reaction routes, microstructure, and J{sub c} property. Meanwhile, a fine powder is beneficial for the grain growth, alignment, and J{sub c} enhancement in fully reacted tapes. The best J{sub c} was achieved in the tape made from the powder after optimizing the phase assemblage and particle size.

  11. Effects of 12-O-tetradecanoylphorbol-13-acetate on the incorporation of labelled precursors into RNA, DNA and protein in epidermis, dermis and subcutis from precancerous mouse skin with reference to enhanced tumorigenesis

    International Nuclear Information System (INIS)

    Bhisey, R.A.; Ramchandani, A.G.; Sirsat, S.M.

    1984-01-01

    The effects of a single application of 1.8 nmol 12-O-tetradecanoylphorbol-13-acetate (TPA) on precursor incorporation into RNA, DNA and protein in the epidermis, dermis and subcutis from 3-methylcholanthrene (MCA) injected precancerous mouse skin were studied at various time points between 3 and 96 h. In the precancerous tissues, the rates of incorporation of [ 3 H]uridine into RNA did not alter appreciably from those in the control tissues; while the rates of [ 3 H]methylthymidine incorporation into DNA were elevated with peaks appearing between 6 and 12 h, at 24 h and at 72 h in epidermis, dermis and subcutis. The rate of incorporation of [ 14 C]leucine into protein was markedly elevated in all the three tissues which showed 3-4 sharp peaks. The maximum stimulation ranged between 14 and 20 times that of the control. A single application of TPA to the precancerous mouse skin induced early stimulation of precursor incorporation into all the three macromolecules in epidermis, dermis and subcutis. The increased stimulation was maintained for 36-72 h. The patterns of incorporation of [ 3 H]methylthymidine into DNA gave rise to 2-3 peaks of elevated uptake in each tissue up to 36-48 h. A lowered rate of DNA synthesis between 48 and 60 h was followed by a peak at 72 h. In each group, epidermal mitotic activity correlated well with spurts of precursor incorporation into cellular DNA. The observations indicate that TPA recruits more cells into the DNA synthetic phase and accelerates selective growth of preneoplastic cells during tumor progression

  12. Precursor polymer compositions comprising polybenzimidazole

    Energy Technology Data Exchange (ETDEWEB)

    Klaehn, John R.; Peterson, Eric S.; Orme, Christopher J.

    2015-07-14

    Stable, high performance polymer compositions including polybenzimidazole (PBI) and a melamine-formaldehyde polymer, such as methylated, poly(melamine-co-formaldehyde), for forming structures such as films, fibers and bulky structures. The polymer compositions may be formed by combining polybenzimidazole with the melamine-formaldehyde polymer to form a precursor. The polybenzimidazole may be reacted and/or intertwined with the melamine-formaldehyde polymer to form the polymer composition. For example, a stable, free-standing film having a thickness of, for example, between about 5 .mu.m and about 30 .mu.m may be formed from the polymer composition. Such films may be used as gas separation membranes and may be submerged into water for extended periods without crazing and cracking. The polymer composition may also be used as a coating on substrates, such as metal and ceramics, or may be used for spinning fibers. Precursors for forming such polymer compositions are also disclosed.

  13. Adsorption of natural organic matter and disinfection byproduct precursors from surface water onto TiO2nanoparticles: pH effects, isotherm modelling and implications for using TiO2for drinking water treatment.

    Science.gov (United States)

    Gora, Stephanie L; Andrews, Susan A

    2017-05-01

    Titanium dioxide is a photocatalyst that can remove organic contaminants of interest to the drinking water treatment industry, including natural organic matter (NOM) and disinfection byproduct (DBP) precursors. The photocatalytic reaction occurs in two steps: adsorption of the contaminant followed by degradation of the adsorbed contaminant upon irradiation with UV light. The second part of this process can lead to the formation of reactive intermediates and negative impacts on treated water quality, such as increased DBP formation potential (DBPfp). Adsorption alone does not result in the formation of reactive intermediates and thus may prove to be a safe way to incorporate TiO 2 into drinking water treatment processes. The goal of this study was to expand on the current understanding of NOM adsorption on TiO 2 and examine it in a drinking water context by observing NOM adsorption from real water sources and evaluating the effects of the resulting reductions on the DBPfp of the treated water. Bottle point isotherm tests were conducted with raw water from two Canadian water treatment plants adjusted to pH 4, pH 6 and pH 8 and dosed with TiO 2 nanoparticles. The DOC results were a good fit to a modified Freundlich isotherm. DBP precursors and liquid chromatography with organic carbon detection NOM fractions associated with DBP formation were removed to some extent at all pHs, but most effectively at pH 4. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Effects of intensive induction and consolidation chemotherapy with idarubicin and high dose cytarabine on minimal residual disease levels in newly diagnosed adult precursor-B acute lymphoblastic leukemia

    Directory of Open Access Journals (Sweden)

    Kenneth F. Bradstock

    2016-12-01

    Full Text Available An intensive induction regimen, consisting of idarubicin and high dose cytarabine, was assessed in 19 adult patients, median age 44 years, with newly diagnosed precursor-B acute lymphoblastic leukemia (ALL. Patients achieving a complete response (CR were given an attenuated consolidation course. The primary endpoints were induction death rate and incidence of serious non-hematological toxicity. Grades 3–4 diarrhoea occurred in 47% of patients during induction. Two patients (11% died during induction therapy, and 2 were withdrawn due to resistant disease or prolonged marrow hypoplasia. Fifteen patients achieved CR (79%, but levels of minimal residual disease (MRD after induction were comparable with those previously observed using a modified pediatric protocol. Overall survival at 5 years was 36.8% while leukemia-free survival was 44.1%. An intensive AML protocol used in adults with ALL resulted in substantial toxicity and provided similar levels of cytoreduction to conventional ALL protocols, without improving long-term outcomes.

  15. Effect of Na2SiO3/NaOH on mechanical properties and microstructure of geopolymer mortar using fly ash and rice husk ash as precursor

    Science.gov (United States)

    Saloma, Hanafiah, Elysandi, Debby Orjina; Meykan, Della Garnesia

    2017-11-01

    Geopolymer concrete is an eco-friendly concrete that can reduce carbon emissions on the earth surface because it used industrial waste material such as fly ash, rice husk ash, bagasse ash, and palm oil fuel. Geopolymer is semi-crystalline amorphous materials which has irregular chemical bonds structure. The material is produced by geosynthesis of aluminosilicates and alkali-silicates which produce the Si-O-Al polymer structure. This research used the ratio of fly ash and rice husk ash as precursors e.g. 100:0, 75:25, 50:50, and 25:75. NaOH solutions of 14 M and Na2SiO3 solutions with the variation e.g. 2.5, 2.75, 3.00, and 3.25 were used as activators on mortar geopolymer mixture. The tests of fresh mortar were slump flow and setting time. The optimum compressive strength is 68.36 MPa for 28 days resulted from mixture using 100% fly ash and Na2SiO3 and NaOH with ratio 2.75. The largest value of slump flow test resulted from mixture using Na2SiO3 and NaOH with ratio 2.50 is 17.25 cm. Based on SEM test results, mortar geopolymer microstructure with mixture RHA 0% has less pores and denser CSH structure.

  16. Effect of elemental sulfur in precursors on the pore structure and surface chemical characteristics of high-surface area activated carbon

    Directory of Open Access Journals (Sweden)

    Jing Zhao

    2017-09-01

    Full Text Available Analog sulfur-containing precursors (ASCPs have been prepared by adding a certain amount of elemental sulfur (ES into petroleum coke (PC for synthesis of high-surface area activated carbon (HAC. ASCPs make it feasible to control the speciation and content of sulfur in ASCPs, so as to accurately investigate the influence of ES on the pore structure and surface chemical characteristics of the resultant HAC. The results indicate that ES in ASCPs can react with activator KOH and consume a part of KOH amount, thus leading to the deficiency of actual KOH amount for PC activation, eventually making a decrease in the specific surface area and pore volume of HAC. Interestingly, some of ES in ASCPs is transformed into organic sulfur thioether (C–S–C and sulfate (C–SO4–C or sulfonate (C–SO3–C on HAC surface during the activation process. Therefore, the surface chemical characteristics of HAC are modified correspondingly.

  17. Synthesis of nano-sized ceria (CeO2 particles via a cerium hydroxy carbonate precursor and the effect of reaction temperature on particle morphology

    Directory of Open Access Journals (Sweden)

    Majid Farahmandjou

    2015-06-01

    Full Text Available Cerium oxide (CeO2 or ceria has been shown to be an interesting support material for noble metals in catalysts designed for emission control, mainly due to its oxygen storage capacity. Ceria nanoparticles were prepared by precipitation method. The precursor materials used in this research were cerium nitrate hexahydrate (as a basic material, potassium carbonate and potassium hydroxide (as precipitants. The morphological properties were characterized by high resolution transmission electron microscopy (HRTEM, scanning electron microscopy (SEM and X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR and UV-Vis spectrophotometer. XRD results showed face centered cubic CeO2 nanoparticles for annealed nanoparticles at 1000°C. SEM measurement showed that by increasing the calcinations temperature from 200 to 600°C, the crystallite size decreased from 90 to 28 nm. The SEM results showed that the size of the CeO2 nanoparticles decreased with increasing temperature. The particle size of CeO2 was around 25 nm as estimated by XRD technique and direct HRTEM observation. SEM and TEM studies showed that the morphology of the prepared powder was sphere-like with a narrow size distribution. The sharp peaks in FTIR spectrum determined the purity of CeO2 nanoparticles and absorbance peak of UV-Vis spectrum showed the small band gap energy of 3.26 ev.

  18. Effect of pH and sulfur precursor concentration on electrochemically deposited CZTS thin films using glycine as the complexing agent

    Science.gov (United States)

    Paraye, Akanksha; Sani, Rabiya; Ramachandran, Manivannan; Selvam, Noyel Victoria

    2018-03-01

    Copper zinc tin sulfide (CZTS) a promising quaternary chalcogenide material was deposited using single step electrodeposition using glycine as the complexing agent. The deposition was studied at different sulfur concentrations and at different pH. The pH of the electrolyte was found to influence the stoichiometry of the deposits significantly. The deposits formed at pH 2.5 showed satisfactory stoichiometry. The thickness of the deposits was observed to decrease with increase in sulfur concentration and pH. The transmission electron spectroscopy analysis showed the formation of flower shaped core shell particles from the electrolyte that contained 80 mM sulfur precursor at pH 2.5. The band gap of the deposits was found to be in the range from 1.57 eV to 2.1 eV. X-ray diffraction analysis showed that the as synthesized particles were amorphous in nature, the crystallinity of which improved with annealing. The Mott Schottky analysis of the deposits in 0.1 M sodium perchlorate showed that the particles exhibited p-type conductivity.

  19. Effect of mesenchymal precursor cells on the systemic inflammatory response and endothelial dysfunction in an ovine model of collagen-induced arthritis.

    Directory of Open Access Journals (Sweden)

    Laura M Dooley

    Full Text Available Mesenchymal precursor cells (MPC are reported to possess immunomodulatory properties that may prove beneficial in autoimmune and other inflammatory conditions. However, their mechanism of action is poorly understood. A collagen-induced arthritis model has been previously developed which demonstrates local joint inflammation and systemic inflammatory changes. These include not only increased levels of inflammatory markers, but also vascular endothelial cell dysfunction, characterised by reduced endothelium-dependent vasodilation. This study aimed to characterise the changes in systemic inflammatory markers and endothelial function following the intravenous administration of MPC, in the ovine model.Arthritis was induced in sixteen adult sheep by administration of bovine type II collagen into the hock joint following initial sensitisation. After 24h, sheep were administered either 150 million allogeneic ovine MPCs intravenously, or saline only. Fibrinogen and serum amyloid-A were measured in plasma to assess systemic inflammation, along with pro-inflammatory and anti-inflammatory cytokines. Animals were necropsied two weeks following arthritis induction. Coronary and digital arterial segments were mounted in a Mulvaney-Halpern wire myograph. The relaxant response to endothelium-dependent and endothelium-independent vasodilators was used to assess endothelial dysfunction.Arthritic sheep treated with MPC demonstrated a marked spike in plasma IL-10, 24h following MPC administration. They also showed significantly reduced plasma levels of the inflammatory markers, fibrinogen and serum amyloid A, and increased HDL. Coronary arteries from RA sheep treated with MPCs demonstrated a significantly greater maximal relaxation to bradykinin when compared to untreated RA sheep (253.6 ± 17.1% of pre-contracted tone vs. 182.3 ± 27.3% in controls, and digital arteries also demonstrated greater endothelium-dependent vasodilation. This study demonstrated that MPCs

  20. Method and apparatus for enhanced sequencing of complex molecules using surface-induced dissociation in conjunction with mass spectrometric analysis

    Science.gov (United States)

    Laskin, Julia [Richland, WA; Futrell, Jean H [Richland, WA

    2008-04-29

    The invention relates to a method and apparatus for enhanced sequencing of complex molecules using surface-induced dissociation (SID) in conjunction with mass spectrometric analysis. Results demonstrate formation of a wide distribution of structure-specific fragments having wide sequence coverage useful for sequencing and identifying the complex molecules.

  1. Phonon-mediated decay of an atom in a surface-induced potential

    International Nuclear Information System (INIS)

    Kien, Fam Le; Hakuta, K.; Dutta Gupta, S.

    2007-01-01

    We study phonon-mediated transitions between translational levels of an atom in a surface-induced potential. We present a general master equation governing the dynamics of the translational states of the atom. In the framework of the Debye model, we derive compact expressions for the rates for both upward and downward transitions. Numerical calculations for the transition rates are performed for a deep silica-induced potential allowing for a large number of bound levels as well as free states of a cesium atom. The total absorption rate is shown to be determined mainly by the bound-to-bound transitions for deep bound levels and by bound-to-free transitions for shallow bound levels. Moreover, the phonon emission and absorption processes can be orders of magnitude larger for deep bound levels as compared to the shallow bound ones. We also study various types of transitions from free states. We show that, for thermal atomic cesium with a temperature in the range from 100 μK to 400 μK in the vicinity of a silica surface with a temperature of 300 K, the adsorption (free-to-bound decay) rate is about two times larger than the heating (free-to-free upward decay) rate, while the cooling (free-to-free downward decay) rate is negligible

  2. Effect of pores formation process and oxygen plasma treatment to hydroxyapatite formation on bioactive PEEK prepared by incorporation of precursor of apatite.

    Science.gov (United States)

    Yabutsuka, Takeshi; Fukushima, Keito; Hiruta, Tomoko; Takai, Shigeomi; Yao, Takeshi

    2017-12-01

    When bioinert substrates with fine-sized pores are immersed in a simulated body fluid (SBF) and the pH value or the temperature is increased, fine particles of calcium phosphate, which the authors denoted as 'precursor of apatite' (PrA), are formed in the pores. By this method, hydroxyapatite formation ability can be provided to various kinds of bioinert materials. In this study, the authors studied fabrication methods of bioactive PEEK by using the above-mentioned process. First, the fine-sized pores were formed on the surface of the PEEK substrate by H 2 SO 4 treatment. Next, to provide hydrophilic property to the PEEK, the surfaces of the PEEK were treated with O 2 plasma. Finally, PrA were formed in the pores by the above-mentioned process, which is denoted as 'Alkaline SBF' treatment, and the bioactive PEEK was obtained. By immersing in SBF with the physiological condition, hydroxyapatite formation was induced on the whole surface of the substrate within 1day. The formation of PrA directly contributed to hydroxyapatite formation ability. By applying the O 2 plasma treatment, hydroxyapatite formation was uniformly performed on the whole surface of the substrate. The H 2 SO 4 treatment contributed to a considerable enhancement of adhesive strength of the formed hydroxyapatite layer formed in SBF because of the increase of surface areas of the substrate. As a comparative study, the sandblasting method was applied as the pores formation process instead of the H 2 SO 4 treatment. Although hydroxyapatite formation was provided also in this case, however, the adhesion of the formed hydroxyapatite layer to the substrate was not sufficient even if the O 2 plasma treatment was conducted. This result indicates that the fine-sized pores should be formed on the whole surface of the substrate uniformly to achieve high adhesive strength of the hydroxyapatite layer. Therefore, it is considered that the H 2 SO 4 treatment before the O 2 plasma and the 'Alkaline SBF' treatment

  3. Temperature and irradiation effects on the behaviour of 14C and its precursor 14N in nuclear graphite. Study of a decontamination process using steam reforming

    International Nuclear Information System (INIS)

    Silbermann, Gwennaelle

    2013-01-01

    The dismantling of UNGG reactors in France will generate about 23 000 tons of radioactive graphite wastes. To manage these wastes, the radiological inventory and data on radionuclides (RN) location and speciation should be determined. 14 C was identified as an important RN for disposal due to its high initial activity and the risk of release of a mobile organic fraction in environment, after water ingress into the disposal. Hence, the objective of this thesis, carried out in partnership with EDF is to implement experimental studies to simulate and evaluate the impact of temperature, irradiation and graphite radiolytic corrosion on the in reactor behavior of 14 C and its precursor, 14 N. The obtained data are then used to study the thermal decontamination of graphite in presence of water vapor. The experimental approach aims at simulating the presence of 14 C and 14 N by the respective ion implantation of 13 C and 14 N or 15 N in virgin graphite. This study shows that, in the temperature range reached during reactor operation, (100-500 C) and without radiolytic corrosion, 13 C is thermally stable whatever the initial graphite structure. Moreover, irradiation experiments were performed on heated graphite (500 C) put in contact with a gas representative of the radiolized coolant gas. They show the synergistic role played by the oxidative species and the graphite structure disorder on the enhancement of 13 C mobility resulting in the gasification of the graphite surface and/or the selective oxidation of 13 C more weakly bound than 12 C. Concerning the pristine nitrogen, we showed first that the surface concentration reaches several hundred ppm (≤500 ppm at) and decreases at deeper depths to about 160 ppm at.. Unlike implanted 13 C, implanted nitrogen migrates at 500 C when the graphite is highly disordered (about 8 dpa) while remaining stable for a lower disorder rate (0.14 dpa). Experiments also show the synergistic role by electronic excitations and temperature

  4. Alkoxide-based precursors for direct electrospinning of alumina fibers

    Science.gov (United States)

    Maneeratana, Vasana

    The vision for space exploration in 2004 reinvigorated excitement that was engendered during the 1960's space race. Looking to assist NASA's agency wide mission to develop new technologies to enhance space travel, it is the ultimate goal of this work to support future missions with a hand-held electrospinning apparatus to instantaneously repair existing crucial ceramic fiber structures, such as spacesuits, insulative foams, and tiles. In this research, a new type of precursor is designed based from aluminum alkoxide-based precursors, since alumina serves as a base material for a majority of high-temperature applications. The structure-processing behavior of these precursors is subsequently studied. New precursors of aluminum alkoxides were prepared by modifying solutions; as a result various types of structures were produced, ranging from continuous hollow fibers, continuous solid fibers, or hollow particles. Direct electrospinning with these alkoxide-based precursors yielded an average of 1.9 g/hr of Al2O3, compared to literature with the highest theoretical yield calculated to be 0.68 g/hr. Further exploration of electrospinning parameters found that flow rate directly related to exposure times; therefore fibers were produced in the atmosphere through hydrolysis/condensation with simultaneous solvent evaporation. Furthermore other processing parameters, including the effect of the microstructure due to processing in an electric field were studied. It was found that electrospinning promotes the reaction of the alkoxide, which thereby reduces trapped solvents. As a result of firing schedules, the fibers' hollow features were preserved, and precursors with volatile species resulted in near net shaped fibers. At low firing temperatures, specific surface areas in the range of 330-345 m 2/g were found electrospun fibers. Additionally modified precursors lowered alpha transitions of fibers down to ˜900°C.

  5. Premarital precursors of marital infidelity.

    Science.gov (United States)

    Allen, Elizabeth S; Rhoades, Galena Kline; Stanley, Scott M; Markman, Howard J; Williams, Tamara; Melton, Jessica; Clements, Mari L

    2008-06-01

    Premarital precursors of infidelity were evaluated in a sample of 72 couples (N = 144) who were taking part in a longitudinal study of marriage. Premarital self-report and observational data were compared for couples who experienced infidelity and those who did not experience infidelity in the first years of marriage. Couples in which the male engaged in marital infidelity were characterized, premaritally, by significantly lower male sexual satisfaction, lower male positive communication, and higher female invalidation, whereas couples in which the female went on to engage in infidelity were characterized, premaritally, by significantly lower levels of female positive communication, higher levels of male and female negative communication, and higher levels of male and female invalidation. Implications of the findings for future research on the prediction and prevention of infidelity are discussed.

  6. Effect of different precursors on generation of reference spectra for structural molecular background correction by solid sampling high-resolution continuum source graphite furnace atomic absorption spectrometry: Determination of antimony in cosmetics.

    Science.gov (United States)

    Barros, Ariane Isis; Victor de Babos, Diego; Ferreira, Edilene Cristina; Gomes Neto, José Anchieta

    2016-12-01

    Different precursors were evaluated for the generation of reference spectra and correction of the background caused by SiO molecules in the determination of Sb in facial cosmetics by high-resolution continuum source graphite furnace atomic absorption spectrometry employing direct solid sample analysis. Zeolite and mica were the most effective precursors for background correction during Sb determination using the 217.581nm and 231.147nm lines. Full 2 3 factorial design and central composite design were used to optimize the atomizer temperature program. The optimum pyrolysis and atomization temperatures were 1500 and 2100°C, respectively. A Pd(NO 3 ) 2 /Mg(NO 3 ) 2 mixture was employed as the chemical modifier, and calibration was performed at 217.581nm with aqueous standards containing Sb in the range 0.5-2.25ng, resulting in a correlation coefficient of 0.9995 and a slope of 0.1548s ng -1 . The sample mass was in the range 0.15-0.25mg. The accuracy of the method was determined by analysis of Montana Soil (II) certified reference material, together with addition/recovery tests. The Sb concentration found was in agreement with the certified value, at a 95% confidence level (paired t-test). Recoveries of Sb added to the samples were in the range 82-108%. The limit of quantification was 0.9mgkg -1 and the relative standard deviation (n=3) ranged from 0.5% to 7.1%. From thirteen analyzed samples, Sb was not detected in ten samples (blush, eye shadow and compact powder); three samples (two blush and one eye shadow) presented Sb concentration in the 9.1-14.5mgkg -1 range. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Cryopreservation of GABAergic Neuronal Precursors for Cell-Based Therapy

    Science.gov (United States)

    2017-01-01

    Cryopreservation protocols are essential for stem cells storage in order to apply them in the clinic. Here we describe a new standardized cryopreservation protocol for GABAergic neural precursors derived from the medial glanglionic eminence (MGE), a promising source of GABAergic neuronal progenitors for cell therapy against interneuron-related pathologies. We used 10% Me2SO as cryoprotectant and assessed the effects of cell culture amplification and cellular organization, as in toto explants, neurospheres, or individualized cells, on post-thaw cell viability and retrieval. We confirmed that in toto cryopreservation of MGE explants is an optimal preservation system to keep intact the interneuron precursor properties for cell transplantation, together with a high cell viability (>80%) and yield (>70%). Post-thaw proliferation and self-renewal of the cryopreserved precursors were tested in vitro. In addition, their migration capacity, acquisition of mature neuronal morphology, and potency to differentiate into multiple interneuron subtypes were also confirmed in vivo after transplantation. The results show that the cryopreserved precursor features remained intact and were similar to those immediately transplanted after their dissection from the MGE. We hope this protocol will facilitate the generation of biobanks to obtain a permanent and reliable source of GABAergic precursors for clinical application in cell-based therapies against interneuronopathies. PMID:28122047

  8. Experimental analysis of precursors to severe problem behavior.

    Science.gov (United States)

    Fritz, Jennifer N; Iwata, Brian A; Hammond, Jennifer L; Bloom, Sarah E

    2013-01-01

    Some individuals engage in both mild and severe forms of problem behavior. Research has shown that when mild behaviors precede severe behaviors (i.e., the mild behaviors serve as precursors), they can (a) be maintained by the same source of reinforcement as severe behavior and (b) reduce rates of severe behavior observed during assessment. In Study 1, we developed an objective checklist to identify precursors via videotaped trials for 16 subjects who engaged in problem behavior and identified at least 1 precursor for every subject. In Study 2, we conducted separate functional analyses of precursor and severe problem behaviors for 8 subjects, and obtained correspondence between outcomes in 7 cases. In Study 3, we evaluated noncontingent reinforcement schedule thinning plus differential reinforcement of alternative behavior to reduce precursors, increase appropriate behavior, and maintain low rates of severe behavior during 3 treatment analyses for 2 subjects. Results showed that this treatment strategy was effective for behaviors maintained by positive and negative reinforcement. © Society for the Experimental Analysis of Behavior.

  9. Plutonium Immobilization Project (PIP) Precursor Material Calcine Temperature

    International Nuclear Information System (INIS)

    Cozzi, A.D.

    1999-01-01

    As a result of the end of the Cold War, approximately 50 metric tons of plutonium are no longer needed and have been identified for disposition. A ceramic waste form is the chosen option for immobilization of the excess plutonium. The plutonium ceramic form then will be encased in high-level waste glass using can-in-canister technology for final disposition. The precursor materials are the non-radioactive components that are added to the plutonium feed stream to form the desired phases in the immobilization product. The precursor materials are blended and calcined prior to being mixed with the plutonium feed stream. The purpose of the calcine step is to remove any physical or chemical water retained in the precursors and convert any hydroxides or carbonates to the oxides. Initially, a temperature of 750 degrees C for a period of one hour was chosen for the calcining of the precursors. In this effort, several different calcine temperatures were investigated to evaluate the effect on initial phase formation (in the calcined precursors), thermal expansion of the pressed pellets during heating, and mineralogy and porosity of the final product

  10. Cryopreservation of GABAergic Neuronal Precursors for Cell-Based Therapy.

    Directory of Open Access Journals (Sweden)

    Daniel Rodríguez-Martínez

    Full Text Available Cryopreservation protocols are essential for stem cells storage in order to apply them in the clinic. Here we describe a new standardized cryopreservation protocol for GABAergic neural precursors derived from the medial glanglionic eminence (MGE, a promising source of GABAergic neuronal progenitors for cell therapy against interneuron-related pathologies. We used 10% Me2SO as cryoprotectant and assessed the effects of cell culture amplification and cellular organization, as in toto explants, neurospheres, or individualized cells, on post-thaw cell viability and retrieval. We confirmed that in toto cryopreservation of MGE explants is an optimal preservation system to keep intact the interneuron precursor properties for cell transplantation, together with a high cell viability (>80% and yield (>70%. Post-thaw proliferation and self-renewal of the cryopreserved precursors were tested in vitro. In addition, their migration capacity, acquisition of mature neuronal morphology, and potency to differentiate into multiple interneuron subtypes were also confirmed in vivo after transplantation. The results show that the cryopreserved precursor features remained intact and were similar to those immediately transplanted after their dissection from the MGE. We hope this protocol will facilitate the generation of biobanks to obtain a permanent and reliable source of GABAergic precursors for clinical application in cell-based therapies against interneuronopathies.

  11. 1994 Accident sequence precursor program results

    International Nuclear Information System (INIS)

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

    1996-01-01

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

  12. New bonding configuration on Si(111) and Ge(111) surfaces induced by the adsorption of alkali metals

    DEFF Research Database (Denmark)

    Lottermoser, L.; Landemark, E.; Smilgies, D.M.

    1998-01-01

    The structure of the (3×1) reconstructions of the Si(111) and Ge(111) surfaces induced by adsorption of alkali metals has been determined on the basis of surface x-ray diffraction and low-energy electron diffraction measurements and density functional theory. The (3×1) surface results primarily f...... from the substrate reconstruction and shows a new bonding configuration consisting of consecutive fivefold and sixfold Si (Ge) rings in 〈11̅ 0〉 projection separated by channels containing the alkali metal atoms. © 1998 The American Physical Society......The structure of the (3×1) reconstructions of the Si(111) and Ge(111) surfaces induced by adsorption of alkali metals has been determined on the basis of surface x-ray diffraction and low-energy electron diffraction measurements and density functional theory. The (3×1) surface results primarily...

  13. Development on polymeric precursor routes to produce superconducting nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Lisboa-Filho, P.N. [Departamento de Fisica, Universidade Estadual Paulista (UNESP), Bauru, SP (Brazil)], E-mail: plisboa@fc.unesp.br; Motta, M. [Departamento de Fisica, Universidade Estadual Paulista (UNESP), Bauru, SP (Brazil); Saeki, M.J. [Departamento de Quimica, Universidade Estadual Paulista (UNESP), Bauru, SP (Brazil)

    2007-09-01

    The well-known polymeric precursor route is a simple and low-cost sol-gel method based on the preparation of an aqueous precursor solution of metals followed by the addition of a water-soluble polymer. This method consists of a polyesterification process between a metal chelate complex by using a hydroxycarboxylic acid and a polyhydroxy alcohol. In this work, citric acid (CA), tartaric acid (TA) and ethylenediaminetetraacetic acid (EDTA) are used as the hydroxycarboxylic acid and ethylene glycol (EG) is used as the polyhydroxy alcohol. The effects of the precursor pH solution, time and temperature of polymerization step as well as the combination of different chelating agents in order to obtain nanoscopic YBa{sub 2}Cu{sub 3}O{sub y} samples were traced.

  14. Precursor Events in Environmentally Assisted Cracking Behaviour of Light Metals

    Energy Technology Data Exchange (ETDEWEB)

    Raja, V. S. [Indian Institute of Technology Bombay, Mumbai (India)

    2016-08-15

    Light metal alloys of Mg, Ti, and Al undergo environmentally assisted cracking (EAC). Passive film breakdown and pitting are not only precursor events for stress corrosion, but can accelerate hydrogen evolution that is responsible for hydrogen embrittlement. This is clearly demonstrated in the case of Mg and Ti alloys. The so-called innocuous precipitates, which do not directly participate in either alloy strengthening or EAC can be effective precursors for initiating EAC. This aspect is highlighted using high strength aluminium alloys. Such behaviours lead to a paradigm shift in the design of alloys with resistance to EAC.

  15. Do glycine-extended hormone precursors have clinical significance?

    DEFF Research Database (Denmark)

    Rehfeld, Jens Frederik

    2014-01-01

    Half of the known peptide hormones are C-terminally amidated. Subsequent biogenesis studies have shown that the immediate precursor is a glycine-extended peptide. The clinical interest in glycine-extended hormones began in 1994, when it was suggested that glycine-extended gastrin stimulated cancer...... and clinical effects of glycine-extended precursors for most other amidated hormones than gastrin and cholecystokinin (CCK). The idea of glycine-extended peptides as independent messengers was interesting. But clinical science has to move ahead from ideas that cannot be supported at key points after decades...

  16. Fate of grape flavor precursors during storage on yeast lees.

    Science.gov (United States)

    Loscos, Natalia; Hernández-Orte, Purificación; Cacho, Juan; Ferreira, Vicente

    2009-06-24

    The effect of the addition of a grape flavor precursor extract to a grape juice, before or after fermentation with three different Saccharomyces cerevisiae yeast strains, on the evolution of the wine aroma composition during a 9-month aging period on yeast lees has been studied. Wine aroma compounds were determined by gas chromatography-mass spectrometry after alcoholic fermentation and after 3 and 9 months of storage. The aging of wine on lees caused important changes in the aroma profiles of wines, making the concentrations of three terpenes, norisoprenoids (except beta-damascenone and beta-ionone), 4-allyl-2,6-dimethoxyphenol, ethyl vanillate, syringaldehyde, and ethyl cinnamate increase, whereas the concentrations of most of the rest of compounds tended to decrease. Lees are responsible for the observed increasing trends, except for linalool and alpha-terpineol, and also for a large part of the observed decrements. As expected, the addition of precursors brings about an increment in the levels of most terpenes, norisoprenoids, vanillins, and ethyl cinnamate, and it is after an aging time when differences linked to the level of precursors in the must become more evident. The timing of the addition of precursors has a minor influence, except for beta-damascenone, vanillin, and syringaldehyde, for which supplementation after fermentation is more effective. It has also been observed that the precursor fraction makes the levels of vinylphenols decrease. Finally, it has also been found that lees from different yeast strains may have a slightly different abilities to release volatile compounds derived from precursors.

  17. The isoprenoid-precursor dependence of Plasmodium spp

    NARCIS (Netherlands)

    van der Meer, Jan-Ytzen; Hirsch, Anna K. H.

    2012-01-01

    Due to the increase in resistance of Plasmodium spp. against available antimalarials, there is a need for new, effective and innovative drugs. The non-mevalonate pathway for the biosynthesis of the universal isoprenoid precursors, which is absent in humans, is suggested as an attractive source of

  18. Xylopia Aethiopica lowers Plasma Lipid Precursors of Reproductive ...

    African Journals Online (AJOL)

    Xylopia Aethiopica lowers Plasma Lipid Precursors of Reproductive Hormones in Wister Rats. PC Onyebuagu, CP Aloamaka, JC Igweh. Abstract. This study investigated the effects of dietary Xylopia aethiopica on reproductive hormones and plasma lipids in rats. 10 male and 10 female Wistar rats weighing 200-220g and ...

  19. nanoparticles synthesized by citrate precursor m

    African Journals Online (AJOL)

    user

    Abstract. Ni0.5M0.5Fe2O4 (M = Co, Cu) ferrite nanoparticles were synthesized using citrate precursor method. The citrate precursor was annealed at temperatures 400oC, 450oC, 500oC and 550oC. The annealed powders were characterized using X-ray diffractometer. (XRD) and vibrating sample magnetometer (VSM).

  20. Rapid synthesis of macrocycles from diol precursors

    DEFF Research Database (Denmark)

    Wingstrand, Magnus; Madsen, Charlotte Marie; Clausen, Mads Hartvig

    2009-01-01

    A method for the formation of synthetic macrocycles with different ring sizes from diols is presented. Reacting a simple diol precursor with electrophilic reagents leads to a cyclic carbonate, sulfite or phosphate in a single step in 25-60% yield. Converting the cyclization precursor to a bis-ele...

  1. Precursor conditions related to Zimbabwe's summer droughts

    Science.gov (United States)

    Nangombe, Shingirai; Madyiwa, Simon; Wang, Jianhong

    2018-01-01

    Despite the increasing severity of droughts and their effects on Zimbabwe's agriculture, there are few tools available for predicting these droughts in advance. Consequently, communities and farmers are more exposed, and policy makers are always ill prepared for such. This study sought to investigate possible cycles and precursor meteorological conditions prior to drought seasons that could be used to predict impending droughts in Zimbabwe. The Single Z-Index was used to identify and grade drought years between 1951 and 2010 according to rainfall severity. Spectral analysis was used to reveal the cycles of droughts for possible use of these cycles for drought prediction. Composite analysis was used to investigate circulation and temperature anomalies associated with severe and extreme drought years. Results indicate that severe droughts are more highly correlated with circulation patterns and embedded weather systems in the Indian Ocean and equatorial Pacific Ocean than any other area. This study identified sea surface temperatures in the average period June to August, geopotential height and wind vector in July to September period, and air temperature in September to November period as precursors that can be used to predict a drought occurrence several months in advance. Therefore, in addition to sea surface temperature, which was identified through previous research for predicting Zimbabwean droughts, the other parameters identified in this study can aid in drought prediction. Drought cycles were established at 20-, 12.5-, 3.2-, and 2.7-year cycles. The spectral peaks, 12.5, 3.2, and 2.7, had a similar timescale with the luni-solar tide, El Niño Southern Oscillation and Quasi Biennial Oscillation, respectively, and hence, occurrence of these phenomena have a possibility of indicating when the next drought might be.

  2. Effects of ozone as a stand-alone and coagulation-aid treatment on the reduction of trihalomethanes precursors from high DOC and hardness water.

    Science.gov (United States)

    Sadrnourmohamadi, Mehrnaz; Gorczyca, Beata

    2015-04-15

    This study investigates the effect of ozone as a stand-alone and coagulation aid on the removal of dissolved organic carbon (DOC) from the water with a high level of DOC (13.8 mgL(-1)) and calcium hardness (270 mgL(-1)) CaCO3. Natural water collected from the Assiniboine River (Manitoba, Canada) was used in this study. Effectiveness of ozone treatment was evaluated by measurement of DOC, DOC fractions, UV254, and trihalomethane formation potential (THMFP). Additionally, zeta potential and dissolved calcium concentration were measured to discern the mechanism of ozone reactions. Results indicated that 0.8 mg O3/mg DOC ozone stand-alone can cause up to 86% UV254 reduction and up to 27% DOC reduction. DOC fractionation results showed that ozone can change the composition of DOC in the water samples, converting the hydrophobic fractions into hydrophilic ones and resulting in the reduction of THMFP. Also, ozone caused a decrease in particle stability and dissolved calcium concentration. These simultaneous ozonation effects caused improved water flocculation and enhanced removal of DOC. This resulted in reduction of the coagulant dosage when ozone doses higher than 0.2 mg O3/mg DOC were applied prior to coagulation with ferric sulfate. Also, pre-ozonation-coagulation process achieved preferential THMFP removal for all of the ozone doses tested (0-0.8 mg O3/mg DOC), leading to a lower specific THMFP in pre-ozonated-coagulated waters than in the corresponding ozonated waters. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Effect of lanthanide on the microstructure and structure of LnMn0.5Fe0.5O3 nanoparticles with Ln=La, Pr, Nd, Sm and Gd prepared by the polymer precursor method

    International Nuclear Information System (INIS)

    Romero, Mariano; Faccio, Ricardo; Martínez, Javier; Pardo, Helena; Montenegro, Benjamín; Plá Cid, Cristiani Campos; Pasa, André A.

    2015-01-01

    The synthesis of LnMn 0.5 Fe 0.5 O 3 perovskite nanoparticles by the polymer precursor method showed a strong intrinsic dependence with different lanthanides (Ln=La, Pr, Nd, Sm and Gd). The polymerization level reached in the polymer precursor was proportional to the atomic number of lanthanide with exception of samarium, which showed the formation of a different precursor based in a citrate chelate with ethyleneglycol bonded as adduct. The increasing level of polymerization of the polymer precursors showed the formation of large-size perovskite nanoparticles after its calcination. SAXS and TEM analyses suggested that nanoparticles obtained, using this method, have a squared-like microstructure in connection with the polymer precursor microstructure. Structural analysis showed an orthorhombic structure with a slight decline in the Jahn–Teller distortion when the atomic number of lanthanide increases. Mössbauer spectroscopy showed the presence of a majority site in agreement with the Pbnm orthorhombic structure best fitted with Rietveld refinements and in some cases, a more distorted site attributed to local inhomogeneities and oxygen vacancies. - Highlights: • Precursor polymerization level is lower in the presence of lighter lanthanides. • Lighter lanthanide perovskite nanoparticles after calcination are lower-sized. • Nanoparticles obtained by this method have lamellae microstructure. • Jahn–Teller distortion declines for heavier lanthanide perovskites. • Oxygen vacancy phase was observed in lighter lanthanide perovskites

  4. Controlled Growth of ZnSe Nanocrystals by Tuning Reactivity and Amount of Zinc Precursor

    Directory of Open Access Journals (Sweden)

    Lai-Jun Zhang

    2013-01-01

    Full Text Available Zinc selenide (ZnSe nanocrystals were synthesized via a phosphine-free route using the highly reactive alkylamine-H2Se complex as selenium precursor and zinc precursors with different reactivity. The reactivity of zinc precursor was tuned by using three kinds of zinc carboxylates with different alkyl chain lengths, including zinc acetate, zinc nonanoate, and zinc stearate. The effect of the reactivity and the amount of zinc precursor on nucleation and growth of ZnSe nanocrystals were investigated by ultraviolet-visible absorption and photoluminescence spectra. Result indicates that the growth and optical property of the resulting ZnSe nanocrystals are strongly dependent on the alkyl chain length and the amount of the zinc carboxylates and both shorter alkyl chain length, and more amount of zinc carboxylate will lead to faster growth of ZnSe nanocrystals. This allows that the controlled growth and excellent optical property of high-quality ZnSe nanocrystals can be achieved by combining the different reactivity and the used amount of zinc precursor, such as by using stoichiometric and reactive Zn precursor and Se precursor or by using larger amount of more unreactive Zn precursor relative to the highly reactive alkylamine-H2Se complex precursor.

  5. The effect of changes in π-conjugated terthienyl systems using thienyl and ethylenedioxybenzene functionalized thieno[3,4-b]pyrazine precursors: Multicolored low band gap polymers

    International Nuclear Information System (INIS)

    Tarkuc, Simge; Unver, Elif Kose; Udum, Yasemin Arslan; Tanyeli, Cihangir; Toppare, Levent

    2010-01-01

    New classes of thieno[3,4-b]pyrazines containing thienyl and ethylenedioxy phenyl units on electron-withdrawing moieties of π-conjugated terthienyl were synthesized. The effect of structural differences on electrochemical and optoelectronic properties of the resulting polymers was investigated. Changes in the electronic nature of the functional groups enable to tune the electrochemical properties of the π-conjugated terthienyl monomers by lowering oxidation potential from 0.62 V (DTTP) to 0.56 V (DBTP). Spectroelectrochemical analyses revealed that the neutral polymer (PDBTP) is dark green in its neutral state revealing π-π* transitions in two well-separated bands at 410 and 751 nm. The electronic band gap of polymer, defined as the onset of the π-π* transition, is found to be 1.0 eV. Using the thienyl unit instead of ethylenedioxy phenyl, a red shift in the band gap (0.95 eV) is observed. The polymer, PDTTP, exhibits multicolor electrochromism and can be switched between a dark yellow neutral state, a green intermediate state, and a brown oxidized state. PDBTP also shows a multicolored electrochromic behavior with three distinct states: dark green at the neutral state, a brown intermediate state, and a brown-violet oxidized state.

  6. Oligodendrocyte precursor cell-intrinsic effect of Rheb1 controls differentiation and mediates mTORC1-dependent myelination in brain.

    Science.gov (United States)

    Zou, Yi; Jiang, Wanxiang; Wang, Jianqing; Li, Zhongping; Zhang, Junyan; Bu, Jicheng; Zou, Jia; Zhou, Liang; Yu, Shouyang; Cui, Yiyuan; Yang, Weiwei; Luo, Liping; Lu, Qing R; Liu, Yanhui; Chen, Mina; Worley, Paul F; Xiao, Bo

    2014-11-19

    Rheb1 is an immediate early gene that functions to activate mammalian target of rapamycin (mTor) selectively in complex 1 (mTORC1). We have demonstrated previously that Rheb1 is essential for myelination in the CNS using a Nestin-Cre driver line that deletes Rheb1 in all neural cell lineages, and recent studies using oligodendrocyte-specific CNP-Cre have suggested a preferential role for mTORC1 is myelination in the spinal cord. Here, we examine the role of Rheb1/mTORC1 in mouse oligodendrocyte lineage using separate Cre drivers for oligodendrocyte progenitor cells (OPCs) including Olig1-Cre and Olig2-Cre as well as differentiated and mature oligodendrocytes including CNP-Cre and Tmem10-Cre. Deletion of Rheb1 in OPCs impairs their differentiation to mature oligodendrocytes. This is accompanied by reduced OPC cell-cycle exit suggesting a requirement for Rheb1 in OPC differentiation. The effect of Rheb1 on OPC differentiation is mediated by mTor since Olig1-Cre deletion of mTor phenocopies Olig1-Cre Rheb1 deletion. Deletion of Rheb1 in mature oligodendrocytes, in contrast, does not disrupt developmental myelination or myelin maintenance. Loss of Rheb1 in OPCs or neural progenitors does not affect astrocyte formation in gray and white matter, as indicated by the pan-astrocyte marker Aldh1L1. We conclude that OPC-intrinsic mTORC1 activity mediated by Rheb1 is critical for differentiation of OPCs to mature oligodendrocytes, but that mature oligodendrocytes do not require Rheb1 to make myelin or maintain it in the adult brain. These studies reveal mechanisms that may be relevant for both developmental myelination and impaired remyelination in myelin disease. Copyright © 2014 the authors 0270-6474/14/3415764-15$15.00/0.

  7. Synthesis and structures of metal chalcogenide precursors

    Science.gov (United States)

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

    1990-01-01

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

  8. Boron nitride ceramics from molecular precursors: synthesis, properties and applications.

    Science.gov (United States)

    Bernard, Samuel; Salameh, Chrystelle; Miele, Philippe

    2016-01-21

    Hexagonal boron nitride (h-BN) attracts considerable interest because its structure is similar to that of carbon graphite while it displays different properties which are of interest for environmental and green technologies. The polar nature of the B-N bond in sp(2)-bonded BN makes it a wide band gap insulator with different chemistry on its surface and particular physical and chemical properties such as a high thermal conductivity, a high temperature stability, a high resistance to corrosion and oxidation and a strong UV emission. It is chemically inert and nontoxic and has good environmental compatibility. h-BN also has enhanced physisorption properties due to the dipolar fields near its surface. Such properties are closely dependent on the processing method. Bottom-up approaches consist of transforming molecular precursors into non-oxide ceramics with retention of the structural units inherent to the precursor molecule. The purpose of the present review is to give an up-to-date overview on the most recent achievements in the preparation of h-BN from borazine-based molecular single-source precursors including borazine and 2,4,6-trichloroborazine through both vapor phase syntheses and methods in the liquid/solid state involving polymeric intermediates, called the Polymer-Derived Ceramics (PDCs) route. In particular, the effect of the chemistry, composition and architecture of the borazine-based precursors and derived polymers on the shaping ability as well as the properties of h-BN is particularly highlighted.

  9. Genotoxicity of aflatoxins and their precursors in human cells.

    Science.gov (United States)

    Theumer, M G; Henneb, Y; Khoury, L; Snini, S P; Tadrist, S; Canlet, C; Puel, O; Oswald, I P; Audebert, M

    2018-05-01

    Aflatoxins are found as food contaminant and some of them demonstrate a carcinogenic effect. The aflatoxins biosynthetic pathway involves 15 successive steps. The aim of this study was to compare the toxicity of aflatoxins and their precursors in three human cell lines. We tested the four aflatoxins and two of their metabolites; three early metabolic precursors and two late biosynthetic precursors. Cyclopiazonic acid, synthesized in parallel with aflatoxins, was also tested. The cytotoxicity and the genotoxicity was evaluated with the γH2AX assay in three human cell lines with different bioactivation capacities. Our results indicated that the most genotoxic chemicals in the three cell lines were in decreasing order sterigmatocystin (ST), aflatoxin B1 (AFB1), aflatoxicol (AFL), aflatoxin G1 (AFG1) and versicolorin A (VERA). Aflatoxin M1 (AFM1) demonstrated genotoxic property in only one cell line. The other tested compounds did not demonstrate any genotoxic activity. Overall, our results suggested different genotoxic mechanisms of action for the tested compounds, involving specific bioactivation pathways. Moreover, some metabolic precursors of aflatoxins demonstrated genotoxic potential equivalent or greater to AFB1. This should be taking into account for the development of new strategies intended to reduce the aflatoxins exposure and for human risk assessment. Copyright © 2018 Elsevier B.V. All rights reserved.

  10. Dispersion of Ni2+ions via acetate precursor in the preparation of NaNiPO4nanoparticles: effect of acetate vs. nitrate on the capacitive energy storage properties.

    Science.gov (United States)

    Minakshi Sundaram, M; Mitchell, D R G

    2017-10-17

    The influence of the precursors on the dispersion of Ni 2+ ions and the presence of several other functional groups was investigated in the preparation of sodium nickel phosphate (NaNiPO 4 ) cathode for a supercapacitor study. The dispersion of nickel phases, in the form of nanosheets, is influenced by the type of precursors used in the synthesis. XPS based spectroscopic information on the surface functional groups on NaNiPO 4 show differences between the precursors (i.e.) acetate- and nitrate-derived materials. The benefits of using acetate as an alternative to nitrate are explored by using the NaNiPO 4 nanoparticles as a cathode for supercapacitor applications. The acetate-derived material exhibits improved electrochemical properties possessing both redox behaviour and double-layer capacitance. The results indicate that the metal acetates are homogenously distributed. Acetate functionalization resulted in an improved capacitance of 90 F g -1 compared with that obtained from the nitrate precursor derived material (58 F g -1 ). Capacitance retention and high rate capability were also a feature of the acetate-derived material. The sodium nickel phosphate cathode material has provided useful insights on the precursor chemistry in storing renewable energy have been reported for the first time.

  11. Biochemical Removal of HAP Precursors From Coal

    Energy Technology Data Exchange (ETDEWEB)

    Olson, G.; Tucker, L.; Richards, J.

    1997-07-01

    This project addresses DOE`s interest in advanced concepts for controlling emissions of air toxics from coal-fired utility boilers. We are determining the feasibility of developing a biochemical process for the precombustion removal of substantial percentages of 13 inorganic hazardous air pollutant (HAP) precursors from coal. These HAP precursors are Sb, As, Be, Cd, Cr, Cl, Co, F, Pb, Hg, Mn, Ni, and Se. Although rapid physical coal cleaning is done routinely in preparation plants, biochemical processes for removal of HAP precursors from coal potentially offer advantages of deeper cleaning, more specificity, and less coal loss. Compared to chemical processes for coal cleaning, biochemical processes potentially offer lower costs and milder process conditions. Pyrite oxidizing bacteria, most notably Thiobacillusferrooxidans, are being evaluated in this project for their ability to remove HAP precursors from U.S. coals.

  12. Precursor Parameter Identification for IGBT Prognostics

    Data.gov (United States)

    National Aeronautics and Space Administration — Precursor parameters have been identified to enable development of a prognostic approach for insulated gate bipolar transistors (IGBT). The IGBT were subjected to...

  13. Probabilistic precursor analysis - an application of PSA

    International Nuclear Information System (INIS)

    Hari Prasad, M.; Gopika, V.; Sanyasi Rao, V.V.S.; Vaze, K.K.

    2011-01-01

    Incidents are inevitably part of the operational life of any complex industrial facility, and it is hard to predict how various contributing factors combine to cause the outcome. However, it should be possible to detect the existence of latent conditions that, together with the triggering failure(s), result in abnormal events. These incidents are called precursors. Precursor study, by definition, focuses on how a particular event might have adversely developed. This paper focuses on the events which can be analyzed to assess their potential to develop into core damage situation and looks into extending Probabilistic Safety Assessment techniques to precursor studies and explains the benefits through a typical case study. A preliminary probabilistic precursor analysis has been carried out for a typical NPP. The major advantages of this approach are the strong potential for augmenting event analysis which is currently carried out purely on deterministic basis. (author)

  14. Biochemical Removal of HAP Precursors From Coal

    International Nuclear Information System (INIS)

    Olson, G.; Tucker, L.; Richards, J.

    1997-07-01

    This project addresses DOE's interest in advanced concepts for controlling emissions of air toxics from coal-fired utility boilers. We are determining the feasibility of developing a biochemical process for the precombustion removal of substantial percentages of 13 inorganic hazardous air pollutant (HAP) precursors from coal. These HAP precursors are Sb, As, Be, Cd, Cr, Cl, Co, F, Pb, Hg, Mn, Ni, and Se. Although rapid physical coal cleaning is done routinely in preparation plants, biochemical processes for removal of HAP precursors from coal potentially offer advantages of deeper cleaning, more specificity, and less coal loss. Compared to chemical processes for coal cleaning, biochemical processes potentially offer lower costs and milder process conditions. Pyrite oxidizing bacteria, most notably Thiobacillusferrooxidans, are being evaluated in this project for their ability to remove HAP precursors from U.S. coals

  15. Precursor analyses for German nuclear power plants

    International Nuclear Information System (INIS)

    Babst, Siegfried; Gaenssmantel, Gerhard; Stueck, Reinhard

    2009-01-01

    Precursor analysis is an internationally recognized method for quantifying the safety-relevance of operational events in nuclear power plants. Precursors are operational events in nuclear power plants which had no serious impact, but which could have led to serious impacts, if additional malfunctions had occurred. Examples of such operational events are component failures or transients, for example, the loss of main feedwater. On the basis of the probabilities for the occurrence of additional malfunctions or initiating events precursor analyses determine the probability with which these additional malfunctions during the event occurred would have led to core damage. This conditional probability is a measure for the safety relevance of the operational event occurred. Events, for which the probability of core damages is > 10 -6 , are internationally classified as ''precursor''. (orig.)

  16. Biodegradable mesoporous delivery system for biomineralization precursors.

    Science.gov (United States)

    Yang, Hong-Ye; Niu, Li-Na; Sun, Jin-Long; Huang, Xue-Qing; Pei, Dan-Dan; Huang, Cui; Tay, Franklin R

    2017-01-01

    Scaffold supplements such as nanoparticles, components of the extracellular matrix, or growth factors have been incorporated in conventional scaffold materials to produce smart scaffolds for tissue engineering of damaged hard tissues. Due to increasing concerns on the clinical side effects of using large doses of recombinant bone-morphogenetic protein-2 in bone surgery, it is desirable to develop an alternative nanoscale scaffold supplement that is not only osteoinductive, but is also multifunctional in that it can perform other significant bone regenerative roles apart from stimulation of osteogenic differentiation. Because both amorphous calcium phosphate (ACP) and silica are osteoinductive, a biodegradable, nonfunctionalized, expanded-pore mesoporous silica nanoparticle carrier was developed for loading, storage, and sustained release of a novel, biosilicification-inspired, polyamine-stabilized liquid precursor phase of ACP for collagen biomineralization and for release of orthosilicic acid, both of which are conducive to bone growth. Positively charged poly(allylamine)-stabilized ACP (PAH-ACP) could be effectively loaded and released from nonfunctionalized expanded-pore mesoporous silica nanoparticles (pMSN). The PAH-ACP released from loaded pMSN still retained its ability to infiltrate and mineralize collagen fibrils. Complete degradation of pMSN occurred following unloading of their PAH-ACP cargo. Because PAH-ACP loaded pMSN possesses relatively low cytotoxicity to human bone marrow-derived mesenchymal stem cells, these nanoparticles may be blended with any osteoconductive scaffold with macro- and microporosities as a versatile scaffold supplement to enhance bone regeneration.

  17. Planar half-cell shaped precursor body

    DEFF Research Database (Denmark)

    2015-01-01

    The invention relates to a half-cell shaped precursor body of either anode type or cathode type, the half-cell shaped precursor body being prepared to be free sintered to form a sintered or pre-sintered half-cell being adapted to be stacked in a solid oxide fuel cell stack. The obtained half......-cell has an improved planar shape, which remains planar also after a sintering process and during temperature fluctuations....

  18. Georesistivity precursors to the Tangshan earthquake of 1976

    Directory of Open Access Journals (Sweden)

    F. Lu

    1997-06-01

    Full Text Available Georesistivity precursors and corresponding coseismic effects to the Tangshan earthquake of 1976 are given as follows: 1 resistivity measurements with accuracies of 0.5% or better for over 20 years show that resistivity decreases of several percent, which began approximately 3 years prior to the Tangshan earthquake, were larger than the background fluctuations and hence statistically significant. An outstanding example of an intermediate-term resistivity precursor is given. 2 Georesistivity decreases of several percent observed simultaneously at 9 stations beginning 2-3 years prior to the 1976 Tangshan earthquake are such a pervasive phenomenon that the mean decrease, in percent, can be contoured on a map of the Beijing-Tianjin-Tangshan region. This shows the maximum decrease centered over the epicenter. 3 Corresponding coseismic resistivity changes, ??c/?c, during the M 7.8 Tangshan earthquake were observed at all 16 stations within 240 km from the epicentre. These observed ??c/?c are opposite in sense but similar in spatial distribution to corresponding georesistivity precursors. This observation suggests that the Tangshan earthquake is a rebound process. Calculation indicates that these georesistivity precursors could be represented by a virtual dislocation, of opposite sign to the real dislocation produced at the time of the Tangshan earthquake. These reported ??c/?c offer very convincing evidence for accepting corresponding anomalies prior to the earthquake as its precursors. 4 It is inferred from observed anisotropic decreases in georesistivity that before the Tangshan earthquake the crust was compressed and that the angle between the maximum principal stress ?1 and the earthquake fault was about 80° before the earthquake i.e., the fault was locked by the ?1 which is almost normal to the fault.

  19. Operational experience feedback with precursor analysis

    International Nuclear Information System (INIS)

    Koncar, M.; Ferjancic, M.; Muehleisen, A.; Vojnovic, D.

    2003-01-01

    Experience of practical operation is a valuable source of information for improving the safety and reliability of nuclear power plants. Operational experience feedback (Olef) system manages this aspect of NPP operation. The traditional ways of investigating operational events, such as the root cause analysis (RCA), are predominantly qualitative. RCA as a part of the Olef system provides technical guidance and management expectations in the conduct of assessing the root cause to prevent recurrence, covering the following areas: conditions preceding the event, sequence of events, equipment performance and system response, human performance considerations, equipment failures, precursors to the event, plant response and follow-up, radiological considerations, regulatory process considerations and safety significance. The root cause of event is recognized when there is no known answer on question 'why has it happened?' regarding relevant condition that may have affected the event. At that point the Olef is proceeding by actions taken in response to events, utilization, dissemination and exchange of operating experience information and at the end reviewing the effectiveness of the Olef. Analysis of the event and the selection of recommended corrective/preventive actions for implementation and prioritization can be enhanced by taking into account the information and insights derived from Pasa-based analysis. A Pasa based method, called probabilistic precursor event analysis (PPE A) provides a complement to the RCA approach by focusing on how an event might have developed adversely, and implies the mapping of an operational event on a probabilistic risk model of the plant in order to obtain a quantitative assessment of the safety significance of the event PSA based event analysis provides, due to its quantitative nature, appropriate prioritization of corrective actions. PPEA defines requirements for PSA model and code, identifies input requirements and elaborates following

  20. Low Dose Total Body Irradiation Combined With Recombinant CD19-Ligand × Soluble TRAIL Fusion Protein is Highly Effective Against Radiation-resistant B-precursor Acute Lymphoblastic Leukemia in Mice

    Directory of Open Access Journals (Sweden)

    Fatih M. Uckun

    2015-04-01

    Full Text Available In high-risk remission B-precursor acute lymphoblastic leukemia (BPL patients, relapse rates have remained high post-hematopoietic stem cell transplantation (HSCT even after the use of very intensive total body irradiation (TBI-based conditioning regimens, especially in patients with a high “minimal residual disease” (MRD burden. New agents capable of killing radiation-resistant BPL cells and selectively augmenting their radiation sensitivity are therefore urgently needed. We report preclinical proof-of-principle that the potency of radiation therapy against BPL can be augmented by combining radiation with recombinant human CD19-Ligand × soluble TRAIL (“CD19L–sTRAIL” fusion protein. CD19L–sTRAIL consistently killed radiation-resistant primary leukemia cells from BPL patients as well as BPL xenograft cells and their leukemia-initiating in vivo clonogenic fraction. Low dose total body irradiation (TBI combined with CD19L–sTRAIL was highly effective against (1 xenografted CD19+ radiochemotherapy-resistant human BPL in NOD/SCID (NS mice challenged with an otherwise invariably fatal dose of xenograft cells derived from relapsed BPL patients as well as (2 radiation-resistant advanced stage CD19+ murine BPL with lymphomatous features in CD22ΔE12xBCR-ABL double transgenic mice. We hypothesize that the incorporation of CD19L–sTRAIL into the pre-transplant TBI regimens of patients with very high-risk BPL will improve their survival outcome after HSCT.

  1. Synthesis of aluminum oxide by the polymer precursor method (Pechini) in 4: 1 ratio of citric acid: metal cation: calcination temperature effect; Sintese do oxido de aluminio pelo metodo dos precursores polimericos (Pechini) na relacao 4:1 de acido citrico: cation metalico: efeito da temperatura de calcinacao

    Energy Technology Data Exchange (ETDEWEB)

    Silva, M.C.; Lira, H.L.; Ribeiro, P.C.; Freitas, N.L., E-mail: mirelecsilva@hotmail.com [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais

    2014-07-01

    The technology field is nanopowders prominent in science since these materials fall in various sectors regarding their applications. This work aims at the synthesis of aluminum oxide by polymeric precursors in 4:1 ratio of citric acid:metal cation and evaluate the influence of calcination temperature on their structural and morphological characteristics. The samples after reaction were characterized by XRD and thermal analysis. After calcination 500-1200°C the samples were characterized by XRD, SEM and particle size distribution. The results showed that the variation of the calcination temperature is sufficient to achieve a same material with different structural and morphological characteristics. The most stable phase aluminum oxide arose only after calcination at 1100°C, below 900°C, the amorphous material appeared. As regards the morphology, the change was not as significant as compared to the structure. (author)

  2. Nuclear critical opalescence, a precursor to pion condensation

    International Nuclear Information System (INIS)

    Ericson, M.; Delorme, J.

    1978-03-01

    It is shown that pion condensation in nuclei, a long range phenomenon, has a precursor in the disordered phase, the local ordering of spins which becomes of infinite range at the critical point. A new physical effect arising from this short range order is predicted, namely the enhancement of the static nuclear pion field near the critical momentum. This phenomenon is strongly reminiscent of the critical opalescence observed in the scattering of neutrons by antiferromagnetic subtances

  3. Effect of the nickel precursor on the impregnation and drying of γ-Al2O3 catalyst bodies: a UV-vis and IR micro-spectroscopic study

    NARCIS (Netherlands)

    Espinosa Alonso, L.; de Jong, K.P.; Weckhuysen, B.M.

    2008-01-01

    The elemental preparation steps of impregnation and drying of Ni/g-Al2O3 catalyst bodies have been studied by combining UV-vis and IR microspectroscopy. The influence of the number of chelating ligands in [Ni(en)x(H2O)6-2x]2+ precursor complexes (with en ) ethylenediamine and x ) 0-3) has been

  4. Iron nanoparticles prepared from natural ferrihydrite precursors: kinetics and properties

    International Nuclear Information System (INIS)

    Natural ferrihydrite was used as the precursors for the preparation of the nanocrystalline alpha-Fe powder using heat treatment in hydrogen atmosphere. Transformation temperatures were estimated from the temperature dependences of magnetic moment. Structure and phase composition of the precursors and the final powders were characterized by X-ray diffraction and Mössbauer spectroscopy. Magnetic properties were characterized according to hysteresis loop parameters. The kinetics of the transformation was described using Avrami relation applied on the data of the isothermal time dependence of magnetic moment measurements and subsequently the activation enthalpy of transformation was estimated using Arrhenius plots of their parameters. Comparison of the changes of activation enthalpies derived from a different temperature ranges indicates effects of different processes on formation of alpha-Fe nanoparticles.

  5. Optical precursors from classical waves to single photons

    CERN Document Server

    Chen, JF; Loy, MMT; Du, Shengwang

    2013-01-01

    Ever since Einstein’s special relativity in 1905, the principle of invariant light speed in vacuum has been attracting attention from a wide range of disciplines. How to interpret the principle of light speed? Is light referred to continuous light, or light pulse with definite boundaries? Recent discovery of superluminal medium triggered vigorous discussion within the Physics community. Can communication via such “superluminal channel” break the speed limit and thus violate causality principle? Or, will a single photon, which is not governed by classical laws of Physics, tend to break the speed limit? To solve these problems, in this Brief we bring in optical precursor, the theoretical works for which started as early as 1914. This is a typical optical phenomenon combining wave propagation theory and light-wave interaction. Both theory and experimental works are covered in this Brief. The study of precursor verifies that the effective information carried by light pulses can never exceed the speed of lig...

  6. Whole-cell fungal transformation of precursors into dyes

    Science.gov (United States)

    2010-01-01

    Background Chemical methods of producing dyes involve extreme temperatures and unsafe toxic compounds. Application of oxidizing enzymes obtained from fungal species, for example laccase, is an alternative to chemical synthesis of dyes. Laccase can be replaced by fungal biomass acting as a whole-cell biocatalyst with properties comparable to the isolated form of the enzyme. The application of the whole-cell system simplifies the transformation process and reduces the time required for its completion. In the present work, four fungal strains with a well-known ability to produce laccase were tested for oxidation of 17 phenolic and non-phenolic precursors into stable and non-toxic dyes. Results An agar-plate screening test of the organic precursors was carried out using four fungal strains: Trametes versicolor, Fomes fomentarius, Abortiporus biennis, and Cerrena unicolor. Out of 17 precursors, nine were transformed into coloured substances in the presence of actively growing fungal mycelium. The immobilized fungal biomass catalyzed the transformation of 1 mM benzene and naphthalene derivatives in liquid cultures yielding stable and non-toxic products with good dyeing properties. The type of fungal strain had a large influence on the absorbance of the coloured products obtained after 48-hour transformation of the selected precursors, and the most effective was Fomes fomentarius (FF25). Whole-cell transformation of AHBS (3-amino-4-hydroxybenzenesulfonic acid) into a phenoxazinone dye was carried out in four different systems: in aqueous media comprising low amounts of carbon and nitrogen source, in buffer, and in distilled water. Conclusions This study demonstrated the ability of four fungal strains belonging to the ecological type of white rot fungi to transform precursors into dyes. This paper highlights the potential of fungal biomass for replacing isolated enzymes as a cheaper industrial-grade biocatalyst for the synthesis of dyes and other commercially important

  7. Whole-cell fungal transformation of precursors into dyes

    Directory of Open Access Journals (Sweden)

    Jarosz-Wilkołazka Anna

    2010-07-01

    Full Text Available Abstract Background Chemical methods of producing dyes involve extreme temperatures and unsafe toxic compounds. Application of oxidizing enzymes obtained from fungal species, for example laccase, is an alternative to chemical synthesis of dyes. Laccase can be replaced by fungal biomass acting as a whole-cell biocatalyst with properties comparable to the isolated form of the enzyme. The application of the whole-cell system simplifies the transformation process and reduces the time required for its completion. In the present work, four fungal strains with a well-known ability to produce laccase were tested for oxidation of 17 phenolic and non-phenolic precursors into stable and non-toxic dyes. Results An agar-plate screening test of the organic precursors was carried out using four fungal strains: Trametes versicolor, Fomes fomentarius, Abortiporus biennis, and Cerrena unicolor. Out of 17 precursors, nine were transformed into coloured substances in the presence of actively growing fungal mycelium. The immobilized fungal biomass catalyzed the transformation of 1 mM benzene and naphthalene derivatives in liquid cultures yielding stable and non-toxic products with good dyeing properties. The type of fungal strain had a large influence on the absorbance of the coloured products obtained after 48-hour transformation of the selected precursors, and the most effective was Fomes fomentarius (FF25. Whole-cell transformation of AHBS (3-amino-4-hydroxybenzenesulfonic acid into a phenoxazinone dye was carried out in four different systems: in aqueous media comprising low amounts of carbon and nitrogen source, in buffer, and in distilled water. Conclusions This study demonstrated the ability of four fungal strains belonging to the ecological type of white rot fungi to transform precursors into dyes. This paper highlights the potential of fungal biomass for replacing isolated enzymes as a cheaper industrial-grade biocatalyst for the synthesis of dyes and other

  8. Efeito do vapor d'água na síntese pelo método do precursor polimérico da alumina contendo aditivos Effect of water vapor on the synthesis by the polymeric precursor method of alumina doped powders

    Directory of Open Access Journals (Sweden)

    R. H. R. Castro

    2005-12-01

    Full Text Available A presença de H2O nos processos de síntese e transformação de fase da alumina tem usualmente função catalisadora, diminuindo as temperaturas dos processos e facilitando os possíveis rearranjos atômicos. Neste trabalho mostrou-se que o vapor de H2O durante a síntese pode não apenas acelerar os processos diminuindo as energias de ativação, mas também induzir diferentes formas de ação de aditivos. O estudo foi possível utilizando-se o método dos precursores poliméricos para a síntese dos pós, que permite um controle absoluto do teor de H2O na etapa de cristalização do material. Alumina contendo Mn ou Mg como aditivos foram sintetizadas na ausência de H2O e na presença de excesso controlado desta e fases diferentes para cada situação foram observadas. Uma explicação do fenômeno é descrita em função da dependência da cristalização da gama-Al2O3 na presença de H+ para compensação das vacâncias catiônicas.It is commonly accepted that the presence of H2O during the synthesis and phase transformation of alumina causes decreasing temperatures of these processes since it increases the atomic motilities. In addition to this general concept, in this work H2O vapor is also shown to play an important role on the influence of additives in alumina based systems. Alumina powders containing Mn or Mg were synthesized by the polymeric precursor method under H2O vapor or dry atmosphere during the crystallization stage. Each atmosphere promoted a different phase and an explanation for the phenomenon was given bases on the gamma-Al2O3 crystallization dependence on the H+ presence due to the required cationic vacancies compensations.

  9. Biochemical Removal of HAP Precursors from Coal

    Energy Technology Data Exchange (ETDEWEB)

    Olson, Gregory J

    1997-05-12

    Column biooxidation tests with Kentucky coal confirmed results of earlier shake flask tests showing significant removal from the coal of arsenic, selenium, cobalt, manganese, nickel and cadmium. Rates of pyrite biooxidation in Kentucky coal were only slightly more than half the rates found previously for Indiana and Pittsburgh coals. Removal of pyrite from Pittsburgh coal by ferric ion oxidation slows markedly as ferrous ions accumulate in solution, requiring maintenance of high redox potentials in processes designed for removal of pyrite and hazardous air pollutant (HAP) precursors by circulation of ferric solutions through coal. The pyrite oxidation rates obtained in these tests were used by Unifield Engineering to support the conceptual designs for alternative pyrite and HAP precursor bioleaching processes for the phase 2 pilot plant. Thermophilic microorganisms were tested to determine if mercury could be mobilized from coal under elevated growth temperatures. There was no evidence for mercury removal from coal under these conditions. However, the activity of the organisms may have liberated mercury physically. It is also possible that the organisms dissolved mercury and it readsorbed to the clay preferentially. Both of these possibilities are undergoing further testing. The Idaho National Engineering and Environmental Laboratory's (INEEL) slurry column reactor was operated and several batches of feed coal, product coal, waste solids and leach solutions were submitted to LBL for HAP precursor analysis. Results to date indicate significant removal of mercury, arsenic and other HAP precursors in the combined physical-biological process.

  10. Sol-gel precursors and products thereof

    Science.gov (United States)

    Warren, Scott C.; DiSalvo, Jr., Francis J.; Weisner, Ulrich B.

    2017-02-14

    The present invention provides a generalizable single-source sol-gel precursor capable of introducing a wide range of functionalities to metal oxides such as silica. The sol-gel precursor facilitates a one-molecule, one-step approach to the synthesis of metal-silica hybrids with combinations of biological, catalytic, magnetic, and optical functionalities. The single-source precursor also provides a flexible route for simultaneously incorporating functional species of many different types. The ligands employed for functionalizing the metal oxides are derived from a library of amino acids, hydroxy acids, or peptides and a silicon alkoxide, allowing many biological functionalities to be built into silica hybrids. The ligands can coordinate with a wide range of metals via a carboxylic acid, thereby allowing direct incorporation of inorganic functionalities from across the periodic table. Using the single-source precursor a wide range of functionalized nanostructures such as monolith structures, mesostructures, multiple metal gradient mesostructures and Stober-type nanoparticles can be synthesized. ##STR00001##

  11. Janus microgels produced from functional precursor polymers.

    Science.gov (United States)

    Seiffert, Sebastian; Romanowsky, Mark B; Weitz, David A

    2010-09-21

    Micrometer-sized Janus particles of many kinds can be formed using droplet microfluidics, but in existing methods, the microfluidic templating is strongly coupled to the material synthesis, since droplet solidification occurs through rapid polymerization right after droplet formation. This circumstance limits independent control of the material properties and the morphology of the resultant particles. In this paper, we demonstrate a microfluidic technique to produce functional Janus microgels from prefabricated, cross-linkable precursor polymers. This approach separates the polymer synthesis from the particle gelation, thus allowing the microfluidic droplet templating and the functionalization of the matrix polymer to be performed and controlled in two independent steps. We use microfluidic devices to emulsify semidilute solutions of cross-linkable, chemically modified or unmodified poly(N-isopropylacrylamide) precursors and solidify the drops via polymer-analogous gelation. The resultant microgel particles exhibit two distinguishable halves which contain most of the modified precursors, and the unmodified matrix polymer separates these materials. The spatial distribution of the modified precursors across the particles can be controlled by the flow rates during the microfluidic experiments. We also form hollow microcapsules with two different sides (Janus shells) using double emulsion droplets as templates, and we produce Janus microgels that are loaded with a ferromagnetic additive which allows remote actuation of the microgels.

  12. Precursor Dependent Structural Properties and Antibacterial Activity ...

    Indian Academy of Sciences (India)

    71

    The antibacterial activity of the synthesized CuO were studied against human pathogens like Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacterial strains which are proved to be efficient and precursor dependent. The minimum inhibitory concentration of CuO against E. coli and S. aureus were found to.

  13. Julian del Casal Precursor of Modernism?

    Directory of Open Access Journals (Sweden)

    Onelio Olivera Blanco

    2009-06-01

    Full Text Available This article deals with Modernism as literary school at the end of the XIX century, and its most important representatives. The authors give some elements that in their opinion could be taken into consideration so as to consider Julián del Casal as the legitimate precursor of this literary school in the Hispano-American literature.

  14. Laser-induced metal reduction from liquid electrolyte precursor.

    Science.gov (United States)

    Kim, Dongsoo; Choi, Choljin

    2013-11-01

    A special sort of laser methods such as direct writing of metal and thin film deposition from liquid precursors was developed for the surface processing and the localized metallization of different kinds of materials. Laser radiation initiates the chemical reaction resulted in the reduction of the metal complexes to the metals in the liquid electrolyte, followed by the metal deposition on the substrate with a high degree of the adhesion. In this study, continuous wave of Ar+ laser generated in multiwave regime with laser power from 5 to 500 mW was chosen for the Copper reduction and deposition on SiO2 substrate. In order to investigate the effect of salt precursors on the properties of the deposited structures, two kinds of electrolyte solution were prepared on the base of CuSO4 and CuCl2. It was shown that metal deposition can be initiated at the laser power of 50 mW. The width of the deposits was found to be substantially dependent on the applied laser power. Deposits were revealed as conductive layers and the resistance of the layers depends strongly on the solution temperature and the salt precursor.

  15. Auraptene induces oligodendrocyte lineage precursor cells in a cuprizone-induced animal model of demyelination.

    Science.gov (United States)

    Nakajima, Mitsunari; Shimizu, Risei; Furuta, Kohei; Sugino, Mami; Watanabe, Takashi; Aoki, Rui; Okuyama, Satoshi; Furukawa, Yoshiko

    2016-05-15

    We investigated the effects of auraptene on mouse oligodendroglial cell lineage in an animal model of demyelination induced by cuprizone. Auraptene, a citrus coumarin, was intraperitoneally administered to mice fed the demyelinating agent cuprizone. Immunohistochemical analysis of the corpus callosum and/or Western blotting analysis of brain extracts revealed that cuprizone reduced immunoreactivity for myelin-basic protein, a marker of myelin, whereas it increased immunoreactivity to platelet derived-growth factor receptor-α, a marker of oligodendrocyte precursor cells. Administration of auraptene enhanced the immunoreactivity to oligodendrocyte transcription factor 2, a marker of oligodendrocyte precursor cells and oligodendrocyte lineage precursor cells, but had no effect on immunoreactivity to myelin-basic protein or platelet-derived growth factor receptor-α. These findings suggest that auraptene promotes the production of oligodendrocyte lineage precursor cells in an animal model of demyelination and may be useful for individuals with demyelinating diseases. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Surface-Induced Near-Field Scaling in the Knudsen Layer of a Rarefied Gas

    Science.gov (United States)

    Gazizulin, R. R.; Maillet, O.; Zhou, X.; Cid, A. Maldonado; Bourgeois, O.; Collin, E.

    2018-01-01

    We report on experiments performed within the Knudsen boundary layer of a low-pressure gas. The noninvasive probe we use is a suspended nanoelectromechanical string, which interacts with He 4 gas at cryogenic temperatures. When the pressure P is decreased, a reduction of the damping force below molecular friction ∝P had been first reported in Phys. Rev. Lett. 113, 136101 (2014), 10.1103/PhysRevLett.113.136101 and never reproduced since. We demonstrate that this effect is independent of geometry, but dependent on temperature. Within the framework of kinetic theory, this reduction is interpreted as a rarefaction phenomenon, carried through the boundary layer by a deviation from the usual Maxwell-Boltzmann equilibrium distribution induced by surface scattering. Adsorbed atoms are shown to play a key role in the process, which explains why room temperature data fail to reproduce it.

  17. Modification of the glass surface induced by redox reactions and internal diffusion processes

    DEFF Research Database (Denmark)

    Smedskjær, Morten Mattrup; Deubener, Joachim; Yue, Yuanzheng

    In this paper we report a novel way to modify the glass surface in favor of some physical performances. The main step is to perform iso-thermal treatments on the selected silicate glasses containing transition metal at temperatures near the glass transition temperature for various durations under...... different gases. As a result, we have observed a striking phenomenon, i.e., the outward diffusion of divalent cations occurs not only under an oxidizing atmosphere of heat-treatment, but also under nitrogen, even under reducing atmospheres like H2/N2 (10/90). The extent of the cationic diffusion depends...... on temperature and duration of heat-treatments. The mechanism of the diffusion depends on the type of the gases used for the heat-treatments. In this paper we propose several possible models describing mechanisms of the cationic diffusion, and hence, of the formation of the nano-layer. We also report the effect...

  18. Surface-Induced Frustration in Solid State Polymorphic Transition of Native Cellulose Nanocrystals.

    Science.gov (United States)

    Salminen, Reeta; Baccile, Niki; Reza, Mehedi; Kontturi, Eero

    2017-06-12

    The presence of an interface generally influences crystallization of polymers from melt or from solution. Here, by contrast, we explore the effect of surface immobilization in a direct solid state polymorphic transition on individual cellulose nanocrystals (CNCs), extracted from a plant-based origin. The conversion from native cellulose I to cellulose III crystal occurred via a host-guest inclusion of ethylene diamine inside the crystal. A 60% reduction in CNC width (height) in atomic force microscopy images suggested that when immobilized on a flat modified silica surface, the stresses caused by the inclusion or the subsequent regeneration resulted in exfoliation, hypothetically, between the van der Waals bonded sheets within the crystal. Virtually no changes in dimensions were visible when the polymorphic transition was performed to nonimmobilized CNCs in bulk dispersion. With reservations and by acknowledging the obvious dissimilarities, the exfoliation of cellulose crystal sheets can be viewed as analogous to exfoliation of 2D structures like graphene from a van der Waals stacked solid. Here, the detachment is triggered by an inclusion of a guest molecule inside a host cellulose crystal and the stresses caused by the firm attachment of the CNC on a solid substrate, leading to detachment of molecular sheets or stacks of sheets.

  19. Effect of different MnO{sub 2} precursors on the electrochemical properties of spinel LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} cathode active materials for high-voltage lithium ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Ye, E-mail: mayetju@tju.edu.cn [Department of Applied Chemistry, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Collaborative Innovation Center of Chemical Science and Engineering, Tianjin (China); Tang, Haoqing [Department of Applied Chemistry, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Tang, Zhiyuan, E-mail: zytang46@163.com [Department of Applied Chemistry, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Collaborative Innovation Center of Chemical Science and Engineering, Tianjin (China); Mao, Wenfeng [Department of Applied Chemistry, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Zhang, Xinhe [McNair Technology Company Limited, Dongguan, Guangdong 523700 (China)

    2016-11-15

    Highlights: • Synthesis of spinel LNMO via a facile template method. • The specific morphology of LNMO is closely related to that of MnO{sub 2} precursor. • LNMO using NH{sub 4}HCO{sub 3} as precipitant exhibits superior electrochemical performance. - Abstract: LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} (LNMO) cathode materials with different morphologies are prepared via a facile template method using various MnO{sub 2} precursors. The structures, morphologies and electrochemical properties of the as-prepared LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} samples are tested by various physical and electrochemical methods. The results of characterization show that the spinel LNMO cathode materials have good crystal structure and the MnO{sub 2} precursors have no effect on the final products. Moreover, the specific morphology of LNMO is closely related to that of MnO{sub 2} precursor, and further influence the electrochemical performance. In addition, the LNMO sample using NH{sub 4}HCO{sub 3} as precipitant exhibits excellent rate capability and cyclic stability in all as-prepared samples. Cycled at 0.5 and 1 C, the discharge capacities of LNMO cathode active particles using NH{sub 4}HCO{sub 3} as precipitant are 110.6 and 102.2 after 200 charge–discharge cycles, respectively, which are the largest compared with the LNMO using (NH{sub 4}){sub 2}S{sub 2}O{sub 8} and KMnO{sub 4} as oxidants.

  20. Adaptation to a long term (4 weeks) arginine- and precursor (glutamate, proline and aspartate)-free diet

    Science.gov (United States)

    It is not known whether arginine homeostasis is negatively affected by a "long-term" dietary restriction of arginine and its major precursors in healthy adults. To assess the effects of a 4-week arginine- and precursor-free dietary intake on the regulatory mechanisms of arginine homeostasis in healt...

  1. Fabrication and Analysis of Microscale Aluminum Foam Precursor Particles by Use of Titanium Hydride

    Science.gov (United States)

    Key, Deanna E.

    The creation of aluminum foam precursor particles by use of a blowing agent, Titanium Hydride, is examined. The production of these precursor particles is highly dependent on the mechanical milling process, and the use of a process control agent (methanol) during milling. The effects of the process control agent allow for faster milling times, and the achievement of micro-scale particle sizes is achieved. In addition, the foaming characteristics of these particles are explored in depth, with the comparison of foaming environments, air vs. argon. The argon foaming environment was found to yield better foaming characteristics than that of air. This study is the first to create individual micro-scale aluminum foam precursor particles, as previous studies focused on that of bulk powder compacts. The successful creation of the micron scale aluminum foam precursor particles opens doors for the creation of hybrid foams.

  2. Disinfection by-products/precursor control using an innovative treatment process -- high energy electron beam irradiation

    International Nuclear Information System (INIS)

    Sawal, K.; Millington, B.; Slifker, R.A.; Cooper, W.J.; Nickelsen, M.G.; Kurucz, C.N.; Waite, T.D.

    1993-01-01

    When waters containing naturally occurring humic substances, precursors, are chlorinated, reaction (disinfection) by-products (DBPs) that may compromise the chemical water quality of the drinking water are formed. Two options exist for the treatment of THMs and other DBPs, removal of precursor material prior to chlorination, or destruction of the by-products once they are formed. The authors have initiated a study using an innovative process, high energy electron beam irradiation, as an alternative treatment for the destruction of toxic organic compounds. Preliminary studies indicated that the process would also be effective in the removal of precursors. An added advantage of this process is that is would serve as a primary disinfectant, destroying any toxic compounds in the source water and may assist in the removal of algae and cyanobacteria toxins. This paper discusses studies in precursor removal and control of THMs

  3. Understanding Animal Detection of Precursor Earthquake Sounds.

    Science.gov (United States)

    Garstang, Michael; Kelley, Michael C

    2017-08-31

    We use recent research to provide an explanation of how animals might detect earthquakes before they occur. While the intrinsic value of such warnings is immense, we show that the complexity of the process may result in inconsistent responses of animals to the possible precursor signal. Using the results of our research, we describe a logical but complex sequence of geophysical events triggered by precursor earthquake crustal movements that ultimately result in a sound signal detectable by animals. The sound heard by animals occurs only when metal or other surfaces (glass) respond to vibrations produced by electric currents induced by distortions of the earth's electric fields caused by the crustal movements. A combination of existing measurement systems combined with more careful monitoring of animal response could nevertheless be of value, particularly in remote locations.

  4. Investigations on precursor measures for aeroelastic flutter

    Science.gov (United States)

    Venkatramani, J.; Sarkar, Sunetra; Gupta, Sayan

    2018-04-01

    Wind tunnel experiments carried out on a pitch-plunge aeroelastic system in the presence of fluctuating flows reveal that flutter instability is presaged by a regime of intermittency. It is observed that as the flow speed gradually increases towards the flutter speed, there appears intermittent bursts of periodic oscillations which become more frequent as the wind speed increases and eventually the dynamics transition into fully developed limit cycle oscillations, marking the onset of flutter. The signature from these intermittent oscillations are exploited to develop measures that forewarn a transition to flutter and can serve as precursors. This study investigates a suite of measures that are obtained directly from the time history of measurements and are hence model independent. The dependence of these precursors on the size of the measured data set and the time required for their computation is investigated. These measures can be useful in structural health monitoring of aeroelastic structures.

  5. Metabolic Precursors to Amphetamine and Methamphetamine.

    Science.gov (United States)

    Cody, J D

    1993-12-01

    Analysis and interpretation of amphetamine results is a challenging process made difficult by a number of factors. One of the complications comes from determination of the origin of amphetamine or methamphetamine in a sample. Given the relatively rare occasions that either of these two drugs are prescribed, legal prescription of one of these drugs is seldom a reason for positive findings. A number of other precursor compounds are metabolized by the body to amphetamine or methamphetamine, many of which could be used for legitimate reasons. Fourteen different metabolic precursors of amphetamine or methamphetamine are included in this review. They are amphetaminil, benzphetamine, clobenzorex, deprenyl, dimethylamphetamine, ethylamphetamine, famprofazone, fencamine, fenethylline, fenproporex, furfenorex, mefenorex, mesocarb, and prenylamine. Medical use, metabolism, analysis, and interpretation are described to afford sufficient information to evaluate the possible involvement of these drugs in positive amphetamine or methamphetamine results. Copyright © 1993 Central Police University.

  6. Lu2O3-SiO2-ZrO2 Coatings for Environmental Barrier Application by Solution Precursor Plasma Spraying and Influence of Precursor Chemistry

    Science.gov (United States)

    Darthout, Émilien; Quet, Aurélie; Braidy, Nadi; Gitzhofer, François

    2014-02-01

    As environmental barrier coatings are subjected to thermal stress in gas turbine engines, the introduction of a secondary phase as zircon (ZrSiO4) is likely to increase the stress resistance of Lu2Si2O7 coatings generated by induction plasma spraying using liquid precursors. In a first step, precursor chemistry effect is investigated by the synthesis of ZrO2-SiO2 nanopowders by induction plasma nanopowder synthesis technique. Tetraethyl orthosilicate (TEOS) as silicon precursor and zirconium oxynitrate and zirconium ethoxide as zirconium precursors are mixed in ethanol and produce a mixture of tetragonal zirconia and amorphous silica nanoparticles. The use of zirconium ethoxide precursor results in zirconia particles with diameter below 50 nm because of exothermic thermal decomposition of the ethoxide and its high boiling point with respect to solvent, while larger particles are formed when zirconium oxynitrate is employed. The formation temperature of zircon from zirconia and silica oxides is found at 1425 °C. Second, coatings are synthesized in Lu2O3-ZrO2-SiO2 system. After heat treatment, the doping effect of lutetium on zirconia grains totally inhibits the zircon formation. Dense coatings are obtained with the use of zirconium ethoxide because denser particles with a homogeneous diameter distribution constitute the coating.

  7. [Felice Fontana precursor of neurosciences (author's transl)].

    Science.gov (United States)

    Disertori, B; Piazza, M

    1981-01-01

    The A.A. insert the life and work of the naturalist and chemist Felice Fontana, born in Pomarolo (Trentino), in the frame of 18th century sciences, beside other great names of that century like Carolus Linnaeus, Réaumur, von Haller, Spallanzani, Morgagni, Priestley and Lavoisier. In the field of general biology, the discovery of nucleus and nucleolus and consequently the discovery of the eukaryotic cell, as we say in our days, in his, as well as the one of anabiosis. The A.A. enucleate and analyse the contributions of Fontana to the neurosciences; he has discovered the axon and the myelinic sheath half century before Remak and Purknije; he found out that the white matter of the brain is made of fibres alike those of nerves and the grey matter is made of globules (i.e. cells) mixed up with fibres; he discovered in the retina a part of coming out from the brain; he described the transversal bands of fibres of the skeletal muscles; he was the first to introduce into physiology the law of "all and nothing"; he attributed the irritability to the whole animal life; he identified the pupillar reflexes to the light, the reflex of accommodation, the consensual reflex, the psycho-emotive mydriasis and at last the myosis of sleep. He made experimental searches about nerves and recognised their regeneration, he enumerated various pathological intracranial masses, he made an important anatomopathological research about hydatid cyst in the brain of the sheep affected by "capostorno" and madness, he demonstrated their parasitical nature (he said that the hydated cysts were covered inside by small animals), he come out to formulate the hypothesis that some neuropsychiatric diseases of man can depend from similar aetiology. He declared that passions may have pathological effects (psyco-somatic aetiology), but he has also drawned the attention against the danager of aprioristical generalisation of neurogenical causes in all diseases. The A.A. give to Fontana the palm of precursor

  8. PRECURSORS OF EARTHQUAKES: VLF SIGNALSIONOSPHERE IONOSPHERE RELATION

    Directory of Open Access Journals (Sweden)

    Mustafa ULAS

    2013-01-01

    Full Text Available lot of people have died because of earthquakes every year. Therefore It is crucial to predict the time of the earthquakes reasonable time before it had happed. This paper presents recent information published in the literature about precursors of earthquakes. The relationships between earthquakes and ionosphere are targeted to guide new researches in order to study further to find novel prediction methods.

  9. Radiation response of rodent neural precursor cells

    International Nuclear Information System (INIS)

    Limoli, C.L.; Fike, J.R.

    2003-01-01

    Full text: Therapeutic irradiation of the brain can cause cognitive dysfunction that is not treatable or well understood. Several lines of evidence from our laboratory suggest that radiation induced inhibition of neurogenesis in the hippocampus may be involved. To understand the mechanisms underlying these observations, we initiated studies using neural precursor cells isolated from the adult rat hippocampus. Cells were cultured exponentially and analyzed for acute (0-24h) and chronic (3-33 day) changes in apoptosis and oxidative stress following exposure to X-rays. Oxidative stress was measured using a dye sensitive to reactive oxygen species (ROS) and apoptosis was measured using annexin V binding; each endpoint was quantified by fluorescent automated cell sorting (FACS). Following exposure to X-rays, neural precursor cells exhibit a dose-responsive increase in the level of ROS and apoptosis over acute and chronic time frames. ROS and apoptosis were maximal at 12h, increasing 35 and 37% respectively over that of unirradiated controls. ROS and apoptosis peaked again at 24h, increasing 31 and 21% respectively over controls. Chronic levels of ROS and apoptosis were persistently elevated in a dose-dependent manner. ROS showed significant increases (34-180%) over a 3-4 week interval, while increases in apoptosis were less dramatic, rising 45% by week one before dropping to background. Irradiation of rat neural precursor cells was associated with an increase in p53 protein levels, and the activation of G1/S and G2/M checkpoints. These data suggest that the apoptotic and ROS responses may be tied to p53 dependent regulation of cell cycle control and stress activated pathways. We propose that oxidative stress plays a critical role in the radiation response of neural precursor cells, and discuss how this might contribute to the inhibition of neurogenesis and the cognitive impairment observed in the irradiated CNS

  10. Delayed neutron emission, theory and precursor systematics

    International Nuclear Information System (INIS)

    Jahnsen, T.; Pappas, A.C.; Tunaal, T.

    1968-01-01

    Information on the properties of observed delayed neutron precursor and emitters is reviewed. As far as possible emphasis is laid on charge, mass, half-life, β-energetics, neutron-branching, levels, spin and neutron energy spectra. The theory of delayed neutron emission given by Bohr and Wheeler and later refined is presented and analysed with respect to its potentialities and limitations. Even if the theory gives a good general picture of the process itself, it has not been possible to develop it to such detail as would be necessary for satisfactory delayed neutron precursor systematics. Consequently, the systematics which are available today are based mainly on energetics as criteria, and suggest a wide range (in charge and mass) of precursors, much wider than anticipated, earlier or even now, from those that have already been identified. Nevertheless systematics have their use in a search for precursors and have in recent years resulted in a substantial increase in the member of known species. The process is analysed step by step (i.e. matrix element, Fermi function, level density, spin distribution, ''the energy and the angular momentum paths'', and neutron-to-total width). Improvements are suggested that would give rise to a more realistic treatment, and outlines are given for guiding future work. Emphasis is put onto that experimental and theoretical information which must be obtained before a satisfactory and advanced theoretical treatment can be obtained. Some attempts made along these lines are presented. Their importance in the estimate of P n values and shapes of neutron spectra are shown and discussed. For the latter the more different factors (i.e. |M| 2 , ω(E,J), Γ n / Γ tot , J, π, levels, etc.) are considered, the more evidence is obtained for a ''piling up'' of the neutron spectrum towards low energies. Finally the importance is stressed of detailed delayed neutron studies for considering nuclear structure phenomena. (author)

  11. Delayed Neutron Emission, Theory and Precursor Systematica

    International Nuclear Information System (INIS)

    Jahnsen, T.; Pappas, A.C.; Tunaal, T.

    1968-01-01

    Information on the properties of observed delayed neutron precursor; and emitters is reviewed. As far as possible emphasis is laid on charge, mass, half-life, β-energetics, neutron-branching, levels, spin and neutron energy spectra. The theory of delayed neutron emission given by Bohr and Wheeler and later refined is presented and analysed with respect to its potentialities and limitations. Even if the theory gives a good general picture of the process itself, it has not been possible to develop it to such detail as would be necessary for satisfactory delayed neutron precursor systematics. Consequently, the systematics which are available today are based mainly on energetics as criteria, and suggest a wide range (in charge and mass) of precursors, much wider than anticipated, earlier or even now, from those that have already been identified. Nevertheless systematics have their use in a search for precursors and have in recent years resulted in a substantial increase in the member of known species. The process is analysed step by step (i.e. matrix element, Fermi function, level density, spin distribution, the energy and the angular momentum paths , and neutron-to-total width). Improvements are suggested that would give rise to a more realistic treatment, and outlines are given for guiding future work. Emphasis is put onto that experimental and theoretical information which must be obtained before a satisfactory and advanced theoretical treatment can be obtained. Some attempts made along these lines are presented. Their importance in the estimate of Pn values and shapes of neutron spectra are shown and discussed. For the latter the more different factors (i.e. |M| 2 , ω(E, J), Γ n /Γ tot , J, π, levels, etc.) are considered, the more evidence is obtained for a 'piling up' of the neutron spectrum towards low energies. Finally the importance is stressed of detailed delayed neutron studies for considering nuclear structure phenomena. (author)

  12. Surface-Induced Dissociation and Chemical Reactions of C2D4+ on Stainless Steel, Carbon (HOPG), and Two Different Diamond Surfaces

    Czech Academy of Sciences Publication Activity Database

    Feketeová, L.; Žabka, Ján; Zappa, F.; Grill, V.; Scheier, P.; Märk, T. D.; Herman, Zdeněk

    2009-01-01

    Roč. 20, č. 6 (2009), s. 927-938 ISSN 1044-0305 Institutional research plan: CEZ:AV0Z40400503 Keywords : surface-induced process * diamond surfaces * chemical reactions Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.391, year: 2009

  13. Cellular Kinetics of Perivascular MSC Precursors

    Directory of Open Access Journals (Sweden)

    William C. W. Chen

    2013-01-01

    Full Text Available Mesenchymal stem/stromal cells (MSCs and MSC-like multipotent stem/progenitor cells have been widely investigated for regenerative medicine and deemed promising in clinical applications. In order to further improve MSC-based stem cell therapeutics, it is important to understand the cellular kinetics and functional roles of MSCs in the dynamic regenerative processes. However, due to the heterogeneous nature of typical MSC cultures, their native identity and anatomical localization in the body have remained unclear, making it difficult to decipher the existence of distinct cell subsets within the MSC entity. Recent studies have shown that several blood-vessel-derived precursor cell populations, purified by flow cytometry from multiple human organs, give rise to bona fide MSCs, suggesting that the vasculature serves as a systemic reservoir of MSC-like stem/progenitor cells. Using individually purified MSC-like precursor cell subsets, we and other researchers have been able to investigate the differential phenotypes and regenerative capacities of these contributing cellular constituents in the MSC pool. In this review, we will discuss the identification and characterization of perivascular MSC precursors, including pericytes and adventitial cells, and focus on their cellular kinetics: cell adhesion, migration, engraftment, homing, and intercellular cross-talk during tissue repair and regeneration.

  14. Ionospheric precursors for crustal earthquakes in Italy

    Directory of Open Access Journals (Sweden)

    L. Perrone

    2010-04-01

    Full Text Available Crustal earthquakes with magnitude 6.0>M≥5.5 observed in Italy for the period 1979–2009 including the last one at L'Aquila on 6 April 2009 were considered to check if the earlier obtained relationships for ionospheric precursors for strong Japanese earthquakes are valid for the Italian moderate earthquakes. The ionospheric precursors are based on the observed variations of the sporadic E-layer parameters (h'Es, fbEs and foF2 at the ionospheric station Rome. Empirical dependencies for the seismo-ionospheric disturbances relating the earthquake magnitude and the epicenter distance are obtained and they have been shown to be similar to those obtained earlier for Japanese earthquakes. The dependences indicate the process of spreading the disturbance from the epicenter towards periphery during the earthquake preparation process. Large lead times for the precursor occurrence (up to 34 days for M=5.8–5.9 tells about a prolong preparation period. A possibility of using the obtained relationships for the earthquakes prediction is discussed.

  15. Multilayer Capacitor Dielectrics Produced from Metallo-Organic Precursors.

    Science.gov (United States)

    1987-05-15

    x=O.09) deposited on a Si wafer and fired at 500’C in air showed no evidence of the presence of SnO ,, as shown in Fig. 18. The lattice parameter of...the effect of firing conditions on the electrical properties. At fixed SnO , .-JI .,concentration, the resistivity changed with firing temperature and...metallo-organic precursors is an n- 4type semiconductor . Similar observations were made on the films prepared by other techniques such as vapor

  16. Effects of the precursor concentration and different annealing ambients on the structural, optical, and electrical properties of nanostructured V2O5 thin films deposited by spray pyrolysis technique

    Science.gov (United States)

    Irani, Rowshanak; Rozati, Seyed Mohammad; Beke, Szabolcs

    2018-04-01

    V2O5 thin films were deposited with different precursor concentrations of 0.01, 0.05, and 0.1 M on glass substrates by spray pyrolysis technique, then the optimized films were annealed in different ambients (air, oxygen, and vacuum). The results showed that by increasing the concentration, the films grew along the (001) direction with an orthorhombic structure. Field emission scanning electron microscopy showed that nanorods were formed when depositing 0.05 molar of VCl3. We conclude that with the precursor concentration, the surface nanostructure can be well-controlled. Annealing improved the crystallinity under all ambients, but the best crystallinity was achieved in vacuum. It was revealed that the as-deposited films had the highest transmission, whereas the films annealed in air had the lowest. When annealed in air, the optical band gap decreased from 2.45 to 2.32 eV. The sheet resistance, resistivity, mobility, conductivity, and carrier concentration were measured for all the prepared V2O5 films.

  17. SYNGAS PRODUCTION FROM CO2-REFORMING OF CH4 OVER SOL-GEL SYNTHESIZED Ni-Co/Al2O3-MgO-ZrO2 NANOCATALYST: EFFECT OF ZrO2 PRECURSOR ON CATALYST PROPERTIES AND PERFORMANCE

    Directory of Open Access Journals (Sweden)

    Seyed Mehdi Sajjadi

    2015-05-01

    Full Text Available Ni-Co/Al2O3-MgO-ZrO2 nanocatalyst with utilization of two different zirconia precursors, namely, zirconyl nitrate hydrate (ZNH and zirconyl nitrate solution (ZNS, was synthesized via the sol-gel method. The physiochemical properties of nanocatalysts were characterized by XRD, FESEM, EDX, BET and FTIR analyses and employed for syngas production from CO2-reforming of CH4. XRD patterns, exhibiting proper crystalline structure and homogeneous dispersion of active phase for the nanocatalyst ZNS precursor employed (NCAMZ-ZNS. FESEM and BET results of NCAMZ-ZNS presented more uniform morphology and smaller particle size and consequently higher surface areas. In addition, average particle size of NCAMZ-ZNS was 15.7 nm, which is close to the critical size for Ni-Co catalysts to avoid carbon formation. Moreover, FESEM analysis indicated both prepared samples were nanoscale. EDX analysis confirmed the existence of various elements used and also supported the statements made in the XRD and FESEM analyses regarding dispersion. Based on the excellent physiochemical properties, NCAMZ-ZNS exhibited the best reactant conversion across all of the evaluated temperatures, e.g. CH4 and CO2 conversions were 97.2 and 99% at 850 ºC, respectively. Furthermore, NCAMZ-ZNS demonstrated a stable yield with H2/CO close to unit value during the 1440 min stability test.

  18. Syngas production from CO2-reforming of CH4 over sol-gel synthesized Ni-Co/Al2O3-MgOZrO2 nanocatalyst: effect of ZrO2 precursor on catalyst properties and performance

    International Nuclear Information System (INIS)

    Sajjadi, Seyed Mehdi; Haghighi, Mohammad; Rahmani, Farhad

    2015-01-01

    Ni-Co/Al 2 O 3 -MgO-ZrO 2 nanocatalyst with utilization of two different zirconia precursors, namely, zirconyl nitrate hydrate (ZNH) and zirconyl nitrate solution (ZNS), was synthesized via the sol-gel method. The physiochemical properties of nanocatalysts were characterized by XRD, FESEM, EDX, BET and FTIR analyses and employed for syngas production from CO 2 -reforming of CH 4 . XRD patterns, exhibiting proper crystalline structure and homogeneous dispersion of active phase for the nanocatalyst ZNS precursor employed (NCAMZ-ZNS). FESEM and BET results of NCAMZ-ZNS presented more uniform morphology and smaller particle size and consequently higher surface areas. In addition, average particle size of NCAMZ-ZNS was 15.7 nm, which is close to the critical size for Ni-Co catalysts to avoid carbon formation. Moreover, FESEM analysis indicated both prepared samples were nanoscale. EDX analysis confirmed the existence of various elements used and also supported the statements made in the XRD and FESEM analyses regarding dispersion. Based on the excellent physiochemical properties, NCAMZ-ZNS exhibited the best reactant conversion across all of the evaluated temperatures, e.g. CH 4 and CO 2 conversions were 97.2 and 99% at 850 °C, respectively. Furthermore, NCAMZZNS demonstrated a stable yield with H 2 /CO close to unit value during the 1440 min stability test. (author)

  19. Relative Importance of Different Water Categories as Sources of N-Nitrosamine Precursors.

    Science.gov (United States)

    Zeng, Teng; Glover, Caitlin M; Marti, Erica J; Woods-Chabane, Gwen C; Karanfil, Tanju; Mitch, William A; Dickenson, Eric R V

    2016-12-20

    A comparison of loadings of N-nitrosamines and their precursors from different source water categories is needed to design effective source water blending strategies. Previous research using Formation Potential (FP) chloramination protocols (high dose and prolonged contact times) raised concerns about precursor loadings from various source water categories, but differences in the protocols employed rendered comparisons difficult. In this study, we applied Uniform Formation Condition (UFC) chloramination and ozonation protocols mimicking typical disinfection practice to compare loadings of ambient specific and total N-nitrosamines as well as chloramine-reactive and ozone-reactive precursors in 47 samples, including 6 pristine headwaters, 16 eutrophic waters, 4 agricultural runoff samples, 9 stormwater runoff samples, and 12 municipal wastewater effluents. N-Nitrosodimethylamine (NDMA) formation from UFC and FP chloramination protocols did not correlate, with NDMA FP often being significant in samples where no NDMA formed under UFC conditions. N-Nitrosamines and their precursors were negligible in pristine headwaters. Conventional, and to a lesser degree, nutrient removal wastewater effluents were the dominant source of NDMA and its chloramine- and ozone-reactive precursors. While wastewater effluents were dominant sources of TONO and their precursors, algal blooms, and to a lesser degree agricultural or stormwater runoff, could be important where they affect a major fraction of the water supply.

  20. Polysialic acid bioengineering of neuronal cells by N-acyl sialic acid precursor treatment.

    Science.gov (United States)

    Pon, Robert A; Biggs, Nancy J; Jennings, Harold J

    2007-03-01

    The inherent promiscuity of the polysialic acid (PSA) biosynthetic pathway has been exploited by the use of exogenous unnatural sialic acid precursor molecules to introduce unnatural modifications into cellular PSA, and has found applications in nervous system development and tumor vaccine studies. The sialic acid precursor molecules N-propionyl- and N-butanoyl-mannosamine (ManPr, ManBu) have been variably reported to affect PSA biosynthesis ranging from complete inhibition to de novo production of modified PSA, thus illustrating the need for further investigation into their effects. In this study, we have used a monoclonal antibody (mAb) 13D9, specific to both N-propionyl-PSA and N-butanoyl-PSA (NPrPSA and NBuPSA), together with flow cytometry, to study precursor-treated tumor cells and NT2 neurons at different stages of their maturation. We report that both ManPr and ManBu sialic acid precursors are metabolized and the resultant unnatural sialic acids are incorporated into de novo surface sialylglycoconjugates in murine and human tumor cells and, for the first time, in human NT2 neurons. Furthermore, neither precursor treatment deleteriously affected endogenous PSA expression; however, with NT2 cells, PSA levels were naturally downregulated as a function of their maturation into polarized neurons independent of sialic acid precursor treatment.

  1. Preparation and characterization of poly(glycidyl methacrylate)-grafted magnetic nanoparticles: Effects of the precursor concentration on polyol synthesis of Fe3O4 and [PMDETA]0/[CuBr2]0 ratios on SI-AGET ATRP

    Science.gov (United States)

    Jiang, Liping; Zhou, Xuyang; Wei, Guyun; Lu, Xiaoduo; Wei, Weiping; Qiu, Jianhua

    2015-12-01

    Polymer brushes based on poly(glycidyl methacrylate) (PGMA) have been successfully grafted from the surface of silica coated iron oxide (Fe3O4@SiO2) nanoparticles via surface-initiated activators generated by electron transfer atom transfer radical polymerization (SI-AGET ATRP). The size of the nanoparticles could be adjusted from 7.3 to 9.6 nm by varying the precursor concentration of iron(III) acetylacetonate. The Fe3O4 nanoparticles possessed a highly crystalline structure, and the saturation magnetization of the as-prepared magnetite was strongly related to the particle size. Furthermore, the grafted PGMA content on the magnetic nanoparticles could be controlled by varying the ligand to transition metal ratio in a N,N,N‧,N″,N″-pentamethyldiethylenetriamine (PMDETA)/CuBr2 catalyst system. The maximum grafted content was 23.1% at a ratio of [PMDETA]0/[CuBr2]0 = 2:1.

  2. Non radioactive precursor import into chloroplasts

    International Nuclear Information System (INIS)

    Lombardo, V.A.; Ottado, J.

    2003-01-01

    Full text: Eukaryotic cells have a subcellular organization based on organelles. Protein transport to these organelles is quantitatively important because the majority of cellular proteins are codified in nuclear genes and then delivered to their final destination. Most of the chloroplast proteins are translated on cytoplasmic ribosomes as larger precursors with an amino terminal transit peptide that is necessary and sufficient to direct the precursor to the chloroplast. Once inside the organelle the transit peptide is cleaved and the mature protein adopts its folded form. In this work we developed a system for the expression and purification of the pea ferredoxin-NADP + reductase precursor (preFNR) for its import into chloroplasts in non radioactive conditions. We constructed a preFNR fused in its carboxy terminus to a 6 histidines peptide (preFNR-6xHis) that allows its identification using a commercial specific antibody. The construction was expressed, purified, processed and precipitated, rendering a soluble and active preFNR-6xHis that was used in binding and import into chloroplasts experiments. The reisolated chloroplasts were analyzed by SDS-PAGE, electro-blotting and revealed by immuno-detection using either colorimetric or chemiluminescent reactive. We performed also import experiments labeling preFNR and preFNR-6xHis with radioactive methionine as controls. We conclude that preFNR-6xHis is bound and imported into chloroplasts as the wild type preFNR and that both colorimetric or chemiluminescent detection methods are useful to avoid the manipulation of radioactive material. (author)

  3. The NAD(+) precursor nicotinamide riboside decreases exercise performance in rats.

    Science.gov (United States)

    Kourtzidis, Ioannis A; Stoupas, Andreas T; Gioris, Ioannis S; Veskoukis, Aristidis S; Margaritelis, Nikos V; Tsantarliotou, Maria; Taitzoglou, Ioannis; Vrabas, Ioannis S; Paschalis, Vassilis; Kyparos, Antonios; Nikolaidis, Michalis G

    2016-01-01

    Nicotinamide adenine dinucleotide (NAD(+)) and its phosphorylated form (NADP(+)) are key molecules in ubiquitous bioenergetic and cellular signaling pathways, regulating cellular metabolism and homeostasis. Thus, supplementation with NAD(+) and NADP(+) precursors emerged as a promising strategy to gain many and multifaceted health benefits. In this proof-of-concept study, we sought to investigate whether chronic nicotinamide riboside administration (an NAD(+) precursor) affects exercise performance. Eighteen Wistar rats were equally divided in two groups that received either saline vehicle or nicotinamide riboside at a dose of 300 mg/kg body weight/day for 21 days via gavage. At the end of the 21-day administration protocol, both groups performed an incremental swimming performance test. The nicotinamide riboside group showed a tendency towards worse physical performance by 35 % compared to the control group at the final 10 % load (94 ± 53 s for the nicotinamide riboside group and 145 ± 59 s for the control group; P = 0.071). Our results do not confirm the previously reported ergogenic effect of nicotinamide riboside. The potentially negative effect of nicotinamide riboside administration on physical performance may be attributed to the pleiotropic metabolic and redox properties of NAD(+) and NADP(+).

  4. From chelating precursors to La0.05Sr0.95CoO3-y oxide

    International Nuclear Information System (INIS)

    Hong, L.; Guo, F.; Lin, J.

    1999-01-01

    Several La 0.05 Sr 0.95 CoO 3-y (LSCO-95) powders were synthesized by means of a chelated complex-based precursor approach, which involved pyrolysis of chelating precursors and subsequent calcination of the resulting oxides. This paper focuses on the coordination effects of the precursors on the formation of the crystalline phases of the LSCO-95 oxide, showing that when the precursor is composed of EDTA-metal complexes, the perovskite-type oxide LSCO-95, an electronic-ionic mixed conducting ceramic material, can be achieved. In contrast, those LSCO-95 powders obtained initially from the pyrolysis of the precursors containing other coordination ligands possess only the undesirable hexagonal structure

  5. Ionospheric parameters as the precursors of disturbed geomagnetic conditions

    Science.gov (United States)

    Blagoveshchensky, D. V.; Sergeeva, M. A.; Kozlovsky, A.

    2017-12-01

    Geomagnetic storms and substorms are the principal elements of the disturbed Space Weather conditions. The aim of the study was to reveal the ionospheric precursors that can be used to forecast geomagnetic disturbance beginning. To study the ionospheric processes before, during and after magnetic storms and substorms data from Sodankylä Geophysical Observatory was used (geomagnetic coordinates: 64.1oN, 119.2oE). In earlier works the Main Effect (ME) was revealed for substorms. It consists of the following steps: (a) the increase of critical frequency foF2 from its quiet median before and during the substorm growth phase, four-five hours before To moment that is the moment of the expansion phase onset, (b) the foF2 decrease to the level lower than its median just after To and until Te that is the moment of the end of the expansion phase, (c) the issue ;a; repeated during the recovery phase (d) two bell-shape spikes in the cutoff frequency values foEs: first spike occurs three hours before To, second spike - during the expansion phase within the interval between To and Te. In the present work it is shown that ME manifestations can be used as precursors of magnetic substorms at high-latitudes (geomagnetic latitudes 50oN-65oN). In particular, the foF2 growth some hours before To can be used as a precursor of substorm development. The first foEs bell-shaped spike also can be used for short-term forecasting, two-three hours in advance of a substorm. Furthermore, the storms between 2008 and 2012 were studied. It was revealed that the similar ME also takes place in the case of magnetic storms but within the different time scale. More specifically, the first ME maximum in foF2 values occurs one-two days before the storm beginning and can be used as its precursor. In addition, the foEs spike takes place approximately ten hours before a storm and also can be used for the prediction of the storm beginning.

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

    Directory of Open Access Journals (Sweden)

    Peter Hesemann

    2014-04-01

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

  7. Caffeine alters proliferation of neuronal precursors in the adult hippocampus.

    Science.gov (United States)

    Wentz, Christian T; Magavi, Sanjay S P

    2009-01-01

    Neurogenesis continues through adulthood in the hippocampus and olfactory bulb of mammals. Adult neurogenesis has been implicated in learning and memory, and linked with depression. Hippocampal neurogenesis is increased in response to a number of stimuli, including exposure to an enriched environment, increased locomotor activity, and administration of antidepressants. Adult neurogenesis is depressed in response to aging, stress and sleep deprivation. Intriguingly, caffeine modulates a number of these same stimuli in a dose dependent manner. We examined the dose and duration dependent effects of caffeine on the proliferation, differentiation, and survival of newly generated hippocampal neurons in adult mice. Extended, 7 day caffeine administration, alters the proliferation of adult hippocampal precursors in the mouse in a dose dependent manner; moderate to high doses (20-30 mg/kg per day) of caffeine depress proliferation while supraphysiological doses (60 mg/kg per day) increase proliferation of neuronal precursors. Acute, 1 day administration had no affect on proliferation. Caffeine administration does not affect the expression of early or late markers of neuronal differentiation, or rates of long-term survival. However, neurons induced in response to supraphysiological levels of caffeine have a lower survival rate than control cells; increased proliferation does not yield an increase in long-term neurogenesis. These results demonstrate that physiologically relevant doses of caffeine can significantly depress adult hippocampal neurogenesis.

  8. Preparation of plutonium-bearing ceramics via mechanically activated precursor

    Science.gov (United States)

    Chizhevskaya, S. V.; Stefanovsky, S. V.

    2000-07-01

    The problem of excess weapons plutonium disposition is suggested to be solved by means of its incorporation in stable ceramics with high chemical durability and radiation resistivity. The most promising host phases for plutonium as well as uranium and neutron poisons (gadolinium, hafnium) are zirconolite, pyrochlore, zircon, zirconia [1,2], and murataite [3]. Their production requires high temperatures and a fine-grained homogeneous precursor to reach final waste form with high quality and low leachability. Currently various routes to homogeneous products preparation such as sol-gel technology, wet-milling, and grinding in a ball or planetary mill are used. The best result demonstrates sol-gel technology but this route is very complicated. An alternative technology for preparation of ceramic precursors is the treatment of the oxide batch with high mechanical energy [4]. Such a treatment produces combination of mechanical (fine milling with formation of various defects, homogenization) and chemical (split bonds with formation of active centers—free radicals, ion-radicals, etc.) effects resulting in higher reactivity of the activated batch.

  9. Atomically precise graphene nanoribbon heterojunctions from a single molecular precursor

    Science.gov (United States)

    Nguyen, Giang D.; Tsai, Hsin-Zon; Omrani, Arash A.; Marangoni, Tomas; Wu, Meng; Rizzo, Daniel J.; Rodgers, Griffin F.; Cloke, Ryan R.; Durr, Rebecca A.; Sakai, Yuki; Liou, Franklin; Aikawa, Andrew S.; Chelikowsky, James R.; Louie, Steven G.; Fischer, Felix R.; Crommie, Michael F.

    2017-11-01

    The rational bottom-up synthesis of atomically defined graphene nanoribbon (GNR) heterojunctions represents an enabling technology for the design of nanoscale electronic devices. Synthetic strategies used thus far have relied on the random copolymerization of two electronically distinct molecular precursors to yield GNR heterojunctions. Here we report the fabrication and electronic characterization of atomically precise GNR heterojunctions prepared through late-stage functionalization of chevron GNRs obtained from a single precursor. Post-growth excitation of fully cyclized GNRs induces cleavage of sacrificial carbonyl groups, resulting in atomically well-defined heterojunctions within a single GNR. The GNR heterojunction structure was characterized using bond-resolved scanning tunnelling microscopy, which enables chemical bond imaging at T = 4.5 K. Scanning tunnelling spectroscopy reveals that band alignment across the heterojunction interface yields a type II heterojunction, in agreement with first-principles calculations. GNR heterojunction band realignment proceeds over a distance less than 1 nm, leading to extremely large effective fields.

  10. Surface-induced reactions and dissociations of small acetone, acetonitrile and ethanol cluster ions: competitive chemical reactions, dissociation mechanisms and determination of dissociation energy

    Czech Academy of Sciences Publication Activity Database

    Mair, C.; Fedor, J.; Lezius, M.; Scheier, P.; Probst, M.; Herman, Zdeněk; Märk, T. D.

    2003-01-01

    Roč. 5, - (2003), s. 9.1-9.18 ISSN 1367-2630 R&D Projects: GA ČR GA203/00/0632 Grant - others:Czech-Austria Cooperation Programme in Science and Technology 2000-01 No. 6 Institutional research plan: CEZ:AV0Z4040901 Source of funding: O - operačné programy Keywords : physical chemistry * surface-induced reactions Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.480, year: 2003

  11. Large-eddy simulations of surface-induced turbulence and its implications to the interpretation of eddy-covariance measurements in heterogeneous landscapes

    Science.gov (United States)

    Bohrer, G.; Kenny, W.; Morin, T. H.

    2015-12-01

    We used the RAMS-based Forest Large Eddy Simulations (RAFLES) to evaluate the sensitivity of eddy covariance measurements to land-surface discontinuity. While the sensitivity of eddy covariance measurements to surface heterogeneity is well known, it is, in most cases, no feasible to restrict measurements only to sites where the surface include undisturbed and homogeneous land cover over vast distances around the observation tower. The common approach to handle surface heterogeneity is to use a footprint model and reject observations obtained while the source of observed signal is from a mixture of land-use types, and maintain only measurements where the signal originates mostly from the land-use type of interest. We simulated two scenarios - measurements of fluxes from a small forest-surrounded lake, and measurements near a forest edge. These are two very common scenarios where measurements are bound to be affected by heterogeneity - measurements in small lakes, will, by definition, be in some non-negligible proximity or the lake edge; forest edges are common in any forest, near the forest patch edge but also around disturbed patches and forest gaps. We identify regions where the surface heterogeneity is creating persistent updraft or downdraft. A non-zero mean vertical wind is typically neglected in eddy-covariance measurements. We find that these circulations lead to both vertical and horizontal advection that cannot be easily measured by a single eddy-covariance tower. We identify downwind effects, which are well known, but also quantify the upwind effects. We find that surface-induced circulations may affect the flux measured from a tower up to several canopy heights ahead of the discontinuity. We used the High-resolution Volatile Organic Compound Atmospheric Chemistry in Canopies (Hi-VACC) model to determine the actual measurement footprints throughout the RAFLES domain. We estimated the land-cover type distribution of the source signal at different virtual

  12. Elastic precursor wave decay in shock-compressed aluminum over a wide range of temperature

    Science.gov (United States)

    Austin, Ryan A.

    2018-01-01

    The effect of temperature on the dynamic flow behavior of aluminum is considered in the context of precursor wave decay measurements and simulations. In this regard, a dislocation-based model of high-rate metal plasticity is brought into agreement with previous measurements of evolving wave profiles at 300 to 933 K, wherein the amplification of the precursor structure with temperature arises naturally from the dislocation mechanics treatment. The model suggests that the kinetics of inelastic flow and stress relaxation are governed primarily by phonon scattering and radiative damping (sound wave emission from dislocation cores), both of which intensify with temperature. The manifestation of these drag effects is linked to low dislocation density ahead of the precursor wave and the high mobility of dislocations in the face-centered cubic lattice. Simulations performed using other typical models of shock wave plasticity do not reproduce the observed temperature-dependence of elastic/plastic wave structure.

  13. Vitreous humor and albumin augment the proliferation of cultured retinal precursor cells

    DEFF Research Database (Denmark)

    Yang, Jing; Klassen, Henry; Pries, Mette

    2008-01-01

    Intravitreal injection is an important delivery route for studies involving the transplantation of various types of precursor cells to the retina; however, the effect on these cells of exposure to the vitreous microenvironment has not been specifically investigated. Here vitreous humor was evalua......Intravitreal injection is an important delivery route for studies involving the transplantation of various types of precursor cells to the retina; however, the effect on these cells of exposure to the vitreous microenvironment has not been specifically investigated. Here vitreous humor...... was evaluated for the potential to influence the proliferation of rat retinal precursor cells in vitro. Cells were isolated at embryonic day 19 and plated in standard proliferation medium in the presence or absence of fluid expressed from porcine vitreous humor. Cellular proliferation at different...

  14. Synthesis of S-doped graphene by liquid precursor.

    Science.gov (United States)

    Gao, Hui; Liu, Zheng; Song, Li; Guo, Wenhua; Gao, Wei; Ci, Lijie; Rao, Amrita; Quan, Weijin; Vajtai, Robert; Ajayan, Pulickel M

    2012-07-11

    Doping is a common and effective approach to tailor semiconductor properties. Here, we demonstrate the growth of large-area sulfur (S)-doped graphene sheets on copper substrate via the chemical vapor deposition technique by using liquid organics (hexane in the presence of S) as the precursor. We found that S could be doped into graphene's lattice and mainly formed linear nanodomains, which was proved by elemental analysis, high resolution transmission microscopy and Raman spectra. Measurements on S-doped graphene field-effect transistors (G-FETs) revealed that S-doped graphene exhibited lower conductivity and distinctive p-type semiconductor properties compared with those of pristine graphene. Our approach has produced a new member in the family of graphene based materials and is promising for producing graphene based devices for multiple applications.

  15. Illegal or legitimate use? Precursor compounds to amphetamine and methamphetamine.

    Science.gov (United States)

    Musshoff, F

    2000-02-01

    The interpretation of methamphetamine and amphetamine positive test results in biological samples is a challenge to clinical and forensic toxicology for several reasons. The effects of pH and dilution of urine samples and the knowledge about legitimate and illicit sources have to be taken into account. Besides a potentially legal prescription of amphetamines, many substances metabolize to methamphetamine or amphetamine in the body: amphetaminil, benzphetamine, clobenzorex, deprenyl, dimethylamphetamine, ethylamphetamine, famprofazone, fencamine, fenethylline, fenproporex, furfenorex, mefenorex, mesocarb, and prenylamine. Especially the knowledge of potential origins of methamphetamine and amphetamine turns out to be very important to prevent a misinterpretation of the surrounding circumstances and to prove illegal drug abuse. In this review, potential precursor compounds are described, including their medical use and major clinical effects and their metabolic profiles, as well as some clues which help to identify the sources.

  16. Budget of ozone and precursors over Europe

    Energy Technology Data Exchange (ETDEWEB)

    Roemer, M.G.M.; Bosman, R.; Thijsse, T.; Builtjes, P.J.H.; Esser, P. [IMW-TNO, Delft (Netherlands); Beck, J.P. [RIVM-LLO, Bilthoven (Netherlands); Vosbeek, M. [KEMA, Arnhem (Netherlands)

    1997-12-31

    A three dimensional model for the European boundary layer (the LOTOS model) was used to calculate the budget of ozone and precursors over Europe. For two summer months (July and August) in 1990 the net chemical production of ozone is about 21 Tg/m. By dry deposition 17 Tg/m is lost and transport accounts for a net export of 4 Tg/m into the free troposphere. Large differences in chemical ozone production occur for different regions in Europe. Though the ozone efficiency in terms of ozone produced per NO{sub x} molecule oxidised is much lower in western Europe than elsewhere in Europe the ozone chemically produced per unit area is the highest in western Europe due to the high NO{sub x} emission in this region. (orig.)

  17. Ancient engineers' inventions precursors of the present

    CERN Document Server

    Rossi, Cesare

    2017-01-01

    This book describes the inventions and designs of ancient engineers who are the precursors of the present. The period ranges mainly from 300 B.C. to 1600 A.D. with several exceptions. Many of the oldest inventions are documented by archaeological finds, often very little known, mainly from Pompeii, Herculaneum and Stabiae and reveal a surprising modernity in their conception. Most of the inventions presented in the first four parts of the book were conceived up to the late Roman Empire and may be considered as milestones, each in their respective field. The fifth part concentrates on more recent centuries. The sixth part deals with some building construction techniques. Generally, for each of the presented inventions, three elements of research and reference are provided: written documents (the classics), iconic references (coins, bas-reliefs, etc.) and archaeological findings. The authors did not write this book for engineers only; hence they describe all the devices without assuming wide technical knowledge...

  18. Mars MetNet Precursor Mission Status

    Science.gov (United States)

    Harri, A.-M.; Aleksashkin, S.; Guerrero, H.; Schmidt, W.; Genzer, M.; Vazquez, L.; Haukka, H.

    2013-09-01

    We are developing a new kind of planetary exploration mission for Mars in collaboration between the Finnish Meteorological Institute (FMI), Lavochkin Association (LA), Space Research Institute (IKI) and Institutio Nacional de Tecnica Aerospacial (INTA). The Mars MetNet mission is based on a new semi-hard landing vehicle called MetNet Lander (MNL). The scientific payload of the Mars MetNet Precursor [1] mission is divided into three categories: Atmospheric instruments, Optical devices and Composition and structure devices. Each of the payload instruments will provide significant insights in to the Martian atmospheric behavior. The key technologies of the MetNet Lander have been qualified and the electrical qualification model (EQM) of the payload bay has been built and successfully tested.

  19. Preparation of boron nitride fiber by organic precursor method

    Directory of Open Access Journals (Sweden)

    Yingying Zhou

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

  20. Glucagon's actions are modified by the combination of epinephrine and gluconeogenic precursor infusion.

    Science.gov (United States)

    Gustavson, Stephanie M; Chu, Chang An; Nishizawa, Makoto; Farmer, Ben; Neal, Doss; Yang, Ying; Vaughan, Suzan; Donahue, E Patrick; Flakoll, Paul; Cherrington, Alan D

    2003-09-01

    It was previously shown that glucagon and epinephrine have additive effects on both gluconeogenic and glycogenolytic flux. However, the changes in gluconeogenic substrates may have been limiting and thus may have prevented a synergistic effect on gluconeogenesis and a reciprocal inhibitory effect on glycogenolysis. Thus the aim of the present study was to determine if glucagon has a greater gluconeogenic and a smaller glycogenolytic effect in the presence of both epinephrine and clamped gluconeogenic precursors. Two groups (Epi and G + Epi + P) of 18-h-fasted conscious dogs were studied. In Epi, epinephrine was increased, and in G + Epi + P, glucagon and epinephrine were increased. Gluconeogenic precursors (lactate and alanine) were infused in G + Epi + P to match the rise that occurred in Epi. Insulin and glucose levels were also controlled and were similar in the two groups. Epinephrine and precursor administration increased glucagon's effect on gluconeogenesis (4.5-fold; P < 0.05) and decreased glucagon's effect on glycogenolysis (85%; P = 0.08). Thus, in the presence of both hormones, and when the gluconeogenic precursor supply is maintained, gluconeogenic flux is potentiated and glycogenolytic flux is inhibited.

  1. Studies on the experimental variables effects on rhodium catalyzed hydroformylation of unsaturated fatty esters and comparison of [RhH(CO)(PPh{sub 3}){sub 3}] and [RhCl{sub 3}.3H{sub 2}O] as starting catalytic precursors

    Energy Technology Data Exchange (ETDEWEB)

    Mendes, Ana N.F.; Gregorio, Jose R.; Rosa, Ricardo G. da [Universidade Federal do Rio Grande do Sul, Porto Alegre, RS (Brazil). Inst. de Quimica]. E-mail: rgomes@iq.ufrgs.br

    2005-11-15

    Hydroformylation experiments were performed with technical-grade methyl oleate (MO) and soybean oil (SO) using [RhH(CO)(PPh{sub 3}){sub 3}] and [RhCl{sub 3}.3H{sub 2}O] (double bond/Rh = 745) as catalyst precursors modified or not by triphenylphosphine. [RhH(CO)(PPh{sub 3}){sub 3}] shows 100% conversion and 80-91% selectivity to aldehydes in only 4h for both substrates under mild conditions (100 deg C, 40 bar, CO/H{sub 2} = 2:1, ligand/Rh = 10:1). Despite the rapid isomerization of the soybean oil, producing trans isomers and conjugated dienes, no effects were observed on its further conversion to aldehydes. The reaction of soybean oil conducted with pure [RhCl{sub 3}.3H{sub 2}O] produced only conjugated dienes, and when this precursor was modified with triphenylphosphine (ligand/Rh = 10:1) no reaction was observed at all. Curiously, yellow crystals corresponding to the complex [Rh(Cl)(CO)(PPh{sub 3}){sub 2}] were quantitatively isolated at the end of the reaction. (author)

  2. The route of liquid precursor to ZnO nanoparticles in premixed combustion spray pyrolysis

    Science.gov (United States)

    Widiyastuti, W.; Machmudah, Siti; Nurtono, Tantular; Winardi, Sugeng

    2018-04-01

    Zinc oxide nanoparticles had been successfully synthesized by premixed combustion spray pyrolysis. Zinc acetate was dissolved in distilled water was selected as a liquid precursor. Zinc nitrate was also used for comparison the effect of precursor type on the generated particles morphology and the crystallinity. The premixed combustion reaction used liquefied petroleum gas (LPG) mainly consisting of butane and propane as a fuel and compressed air used as an oxidizer. The liquid precursor was atomized using a custom two fluid nozzle to generate droplets. Then, the droplets were sprayed by the flow of air as a carrier gas into the premixed combustion reactor. The zinc precursor was decomposed to zinc oxide due to the high temperature as a result of combustion reaction inside the reactor resulting in nanoparticles formation. The particle size decreased with the increase of the fuel flow rate. In addition, it can be found that at the same flow rate of fuel, the particle size of zinc oxide synthesized using zinc nitrate is larger than that of the use of zinc acetate as a precursor.

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

    Energy Technology Data Exchange (ETDEWEB)

    Ramuhalli, P.; Meyer, R.M.; Fricke, J.M.; Prowant, M.S.; Coble, J.B.; Griffin, J.W.; Pitman, S.G.; Dahl, M.E.; Kafentzis, T.A.; Roosendaal, T.J.

    2012-09-01

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

  4. Spray drying of silica microparticles for sustained release application with a new sol-gel precursor.

    Science.gov (United States)

    Wang, Bifeng; Friess, Wolfgang

    2017-10-30

    A new precursor, tetrakis(2-methoxyethyl) orthosilicate (TMEOS) was used to fabricate microparticles for sustained release application, specifically for biopharmaceuticals, by spray drying. The advantages of TMEOS over the currently applied precursors are its water solubility and hydrolysis at moderate pH without the need of organic solvents or catalyzers. Thus a detrimental effect on biomolecular drug is avoided. By generating spray-dried silica particles encapsulating the high molecular weight model compound FITC-dextran 150 via the nano spray dryer Büchi-90, we demonstrated how formulation parameters affect and enable control of drug release properties. The implemented strategies to regulate release included incorporating different quantities of dextrans with varying molecular weight as well as adjusting the pH of the precursor solution to modify the internal microstructures. The addition of dextran significantly altered the released amount, while the release became faster with increasing dextran molecular weight. A sustained release over 35days could be achieved with addition of 60 kD dextran. The rate of FITC-Dextran 150 release from the dextran 60 containing particles decreased with higher precursor solution pH. In conclusion, the new precursor TMEOS presents a promising alternative sol-gel technology based carrier material for sustained release application of high molecular weight biopharmaceutical drugs. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. In vitro method determing sensitivity of anticancer agents by incorporation of radioactive precursors

    International Nuclear Information System (INIS)

    Sakakibara, Satoshi

    1983-01-01

    A new sensitivity test of anticancer agents was developed to measure the lethal effects of cancer cells by the incorporation of radioactive precursors. The thousand cancer cells were cultured in a microplate in the presence of anticancer agents. These cells were exposed to radioactive precursors. Two or three days later, the cancer cells were harvested on a glass fiver filter by a multiple automatic cell-harvester and the incorporation of precursors was counted by a liquid scintillation counter. In this study, the in vivo results of drug testing in animal model systems were compared with drug sensitivities. Mice inoculated Ehrlich ascites cells were treated with various kinds of anticancer drugs. The development of the cells was compatible with the result of the sensitivity test. The growths of Lauson and ME-180 cells derived from human cancers implanted subcutaneously to nude mice were also well correlated with this sensitivity test. (author)

  6. The immediate nucleotide precursor, guanosine triphosphate, in the riboflavin biosynthetic pathway

    International Nuclear Information System (INIS)

    Mitsuda, Hisateru; Nakajima, Kenji; Nadamoto, Tomonori

    1977-01-01

    In the present paper, the nucleotide precursor of riboflavin was investigated by experiments with labeled purines using non-growing cells of Eremothecium ashbyii. The added purines, at 10 -4 M, were effectively incorporated into riboflavin at an early stage of riboflavin biosynthesis under the experimental conditions. In particular, both labeled xanthine and labeled guanine were specifically transported to guanosine nucleotides, GMP, GDP, GDP-Mannose and GTP, in the course of the riboflavin biosynthesis. A comparison of specific activities of labeled guanosine nucleotides and labeled riboflavin indicated that the nucleotide precursor of riboflavin is guanosine triphosphate. From the results obtained, a biosynthetic pathway of riboflavin is proposed. (auth.)

  7. Al-doped single-crystalline SiC nanowires synthesized by pyrolysis of polymer precursors.

    Science.gov (United States)

    Yang, Weiyou; Gao, Fengmei; Fan, Yi; An, Linan

    2010-07-01

    Al-doped 6H-SiC nanowires are synthesized by catalyst-assisted pyrolysis of polymer precursors. The obtained nanowires were characterized using scanning electron microscopy, X-ray diffraction, transmission electron microscopy and selective area electron diffraction. We demonstrate that doping concentrations can be controlled by tailoring the Al concentrations in the precursors. We also find that Al-doping has a profound effect on the morphology and emission behavior of the SiC nanowires. The current results suggest a simple technique for synthesizing Al-doped SiC nanomaterials in a controlled manner, which are promising for applications in optical and electronic nanodevices.

  8. Tilt Precursors before Earthquakes on the San Andreas Fault, California.

    Science.gov (United States)

    Johnston, M J; Mortensen, C E

    1974-12-13

    An array of 14 biaxial shallow-borehole tiltmeters (at 1O(-7) radian sensitivity) has been installed along 85 kilometers of the San Andreas fault during the past year. Earthquake-related changes in tilt have been simultaneously observed on up to four independent instruments. At earthquake distances greater than 10 earthquake source dimensions, there are few clear indications of tilt change. For the four instruments with the longest records (> 10 months), 26 earthquakes have occurred since July 1973 with at least one instrument closer than 10 source dimensions and 8 earthquakes with more than one instrument within that distance. Precursors in tilt direction have been observed before more than 10 earthquakes or groups of earthquakes, and no similar effect has yet been seen without the occurrence of an earthquake.

  9. Enumeration of minimal stoichiometric precursor sets in metabolic networks.

    Science.gov (United States)

    Andrade, Ricardo; Wannagat, Martin; Klein, Cecilia C; Acuña, Vicente; Marchetti-Spaccamela, Alberto; Milreu, Paulo V; Stougie, Leen; Sagot, Marie-France

    2016-01-01

    What an organism needs at least from its environment to produce a set of metabolites, e.g. target(s) of interest and/or biomass, has been called a minimal precursor set. Early approaches to enumerate all minimal precursor sets took into account only the topology of the metabolic network (topological precursor sets). Due to cycles and the stoichiometric values of the reactions, it is often not possible to produce the target(s) from a topological precursor set in the sense that there is no feasible flux. Although considering the stoichiometry makes the problem harder, it enables to obtain biologically reasonable precursor sets that we call stoichiometric. Recently a method to enumerate all minimal stoichiometric precursor sets was proposed in the literature. The relationship between topological and stoichiometric precursor sets had however not yet been studied. Such relationship between topological and stoichiometric precursor sets is highlighted. We also present two algorithms that enumerate all minimal stoichiometric precursor sets. The first one is of theoretical interest only and is based on the above mentioned relationship. The second approach solves a series of mixed integer linear programming problems. We compared the computed minimal precursor sets to experimentally obtained growth media of several Escherichia coli strains using genome-scale metabolic networks. The results show that the second approach efficiently enumerates minimal precursor sets taking stoichiometry into account, and allows for broad in silico studies of strains or species interactions that may help to understand e.g. pathotype and niche-specific metabolic capabilities. sasita is written in Java, uses cplex as LP solver and can be downloaded together with all networks and input files used in this paper at http://www.sasita.gforge.inria.fr.

  10. Eruption precursors: Manifestations and strategies for detection

    Science.gov (United States)

    Poland, Michael; Pritchard, Matthew

    2017-04-01

    The past several decades have seen a rapid increase in volcano monitoring and modeling capabilities. Diverse arrays of instrument networks can detect a variety of pre-, co-, and post-eruptive phenomena, and remote sensing observations are available across a range of spatial, temporal, and spectral resolutions. A growing class of models, based on the physics of magmatic systems, are making use of these expanding datastreams, providing probabilistic assessments of such parameters as magma supply, volatile content, and eruption duration. To what extent, however, do these developments heighten our ability to identify eruption precursors? The advent of better data and new models provides an opportunity to reexamine our understanding of pre-eruption unrest, as well as our ability to detect and recognize it as such. An idealized model of the buildup to a volcanic eruption might include magma ascent from a deep source region and accumulation in the mid- to upper crust in the preceding months to years. The process might be manifested by surface inflation and deep long-period earthquakes, and accompanied by an increase in CO2 emissions. As magma continues to accumulate, distal volcano-tectonic earthquakes may result as stress builds on nearby faults, H2S emissions may increase as sulfur in a shallow reservoir is hydrolyzed by groundwater, and fumarole and spring temperatures may increase and show changes in chemistry. In the days to hours before an eruption, sudden changes in the rate and style of earthquakes (including repeating earthquakes and tremor) and deformation may occur as the magma reservoir ruptures and magma moves laterally or vertically. Phreatic eruptions might result as ascending magma comes into contact with groundwater, and SO2 emissions might increase as the path between the magma and surface dries out. How often does such a sequence actually occur? Relatively few volcanoes are comprehensively monitored prior to obvious expressions of unrest, so this is not

  11. Transcription factor Runx1 is pro-neurogenic in adult hippocampal precursor cells.

    Directory of Open Access Journals (Sweden)

    Hirokazu Fukui

    Full Text Available Transcription factor Runx1 (Runt Related Transcription Factor 1, plays an important role in the differentiation of hematopoetic stem cells, angiogenesis and the development of nociceptive neurons. These known functions have in common that they relate to lineage decisions. We thus asked whether such role might also be found for Runx1 in adult hippocampal neurogenesis as a process, in which such decisions have to be regulated lifelong. Runx1 shows a widespread low expression in the adult mouse brain, not particularly prominent in the hippocampus and the resident neural precursor cells. Isoforms 1 and 2 of Runx1 (but not 3 to 5 driven by the proximal promoter were expressed in hippocampal precursor cells ex vivo, albeit again at very low levels, and were markedly increased after stimulation with TGF-β1. Under differentiation conditions (withdrawal of growth factors Runx1 became down-regulated. Overexpression of Runx1 in vitro reduced proliferation, increased survival of precursor cells by reducing apoptosis, and increased neuronal differentiation, while slightly reducing dendritic morphology and complexity. Transfection with dominant-negative Runx1 in hippocampal precursor cells in vitro did not result in differences in neurogenesis. Hippocampal expression of Runx1 correlated with adult neurogenesis (precursor cell proliferation across BXD recombinant strains of mice and covarying transcripts enriched in the GO categories "neural precursor cell proliferation" and "neuron differentiation". Runx1 is thus a plausible candidate gene to be involved in regulating initial differentiation-related steps of adult neurogenesis. It seems, however, that the relative contribution of Runx1 to such effect is complementary and will explain only small parts of the cell-autonomous pro-differentiation effect.

  12. Postnatal administration of memantine rescues TNF-α-induced decreased hippocampal precursor proliferation.

    Science.gov (United States)

    Wang, Zhongke; He, Xie; Fan, Xiaotang

    2018-01-01

    Pro-inflammatory cytokine exposure in early postnatal life triggers clear neurotoxic effects on the developing hippocampus. Tumor necrosis factor alpha (TNF-α) is one of the inflammatory mediators and is a potent inhibitor of neurogenesis. Memantine (MEM) is an uncompetitive N-methyl-d-aspartate (NMDA) receptor antagonist that has been demonstrated to increase the proliferation of hippocampal progenitor cells. However, the effects of MEM on TNF-α-mediated impairment of hippocampal precursor proliferation remain unclear. In this study, mice were exposed to TNF-α and later treated with MEM to evaluate its protective effects on TNF-α-mediated toxicity during hippocampal development. The results indicated that brief exposure to TNF-α on postnatal days 3 and 5 resulted in a significant impairment of hippocampal precursor proliferation and a depletion of hippocampal neural precursor cells (NPCs). This effect was attenuated by MEM treatment. We further confirmed that MEM treatment reversed the TNF-α-induced microglia activation and up-regulation of hippocampal NF-κB, MCP-1 and IL-6 mRNA levels, which may be related to the proliferation and maintenance of NPCs. Overall, our results suggest that MEM treatment protects against TNF-α-induced repression of hippocampal precursor proliferation in postnatal mice by partially attenuating neuroinflammatory responses. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Enumeration of minimal stoichiometric precursor sets in metabolic networks

    NARCIS (Netherlands)

    Andrade, R.; Wannagat, M.; Coimbra Klein, C.; Acuna, V.; Marchetti Spaccamela, A.; Vieira Milreu, P.; Stougie, L.; Sagot, M.-F.

    2016-01-01

    Background: What an organism needs at least from its environment to produce a set of metabolites, e.g. target(s) of interest and/or biomass, has been called a minimal precursor set. Early approaches to enumerate all minimal precursor sets took into account only the topology of the metabolic network

  14. The electromagnetic Brillouin precursor in one-dimensional photonic crystals

    NARCIS (Netherlands)

    Uitham, R.; Hoenders, B. J.

    2008-01-01

    We have calculated the electromagnetic Brillouin precursor that arises in a one-dimensional photonic crystal that consists of two homogeneous slabs which each have a single electron resonance. This forerunner is compared with the Brillouin precursor that arises in a homogeneous double-electron

  15. Geometrizing configurations. Heinrich Hertz and his mathematical precursors

    DEFF Research Database (Denmark)

    Lützen, Jesper

    1999-01-01

    A comparison between the methods used by Heinrich hertz and his mathematician precursors such as Liouville, Lipschitz and Darboux in order to apply differential geometry in mechanics......A comparison between the methods used by Heinrich hertz and his mathematician precursors such as Liouville, Lipschitz and Darboux in order to apply differential geometry in mechanics...

  16. Recent developments in metalorganic precursors for metalorganic chemical vapour deposition

    Science.gov (United States)

    Jones, A. C.; Rushworth, S. A.; Auld, J.

    1995-01-01

    Volatile metalorganic compounds are finding an increasing application in the deposition of metals and semiconductors by metalorganic chemical vapour deposition (MOCVD). In this paper, the use of some new precursor systems in the growth of selected metals and alloys is reviewed with emphasis being placed on precursor chemistry in the gas phase and at the growth surface.

  17. Assimilation of NAD(+) precursors in Candida glabrata.

    Science.gov (United States)

    Ma, Biao; Pan, Shih-Jung; Zupancic, Margaret L; Cormack, Brendan P

    2007-10-01

    The yeast pathogen Candida glabrata is a nicotinamide adenine dinucleotide (NAD(+)) auxotroph and its growth depends on the environmental supply of vitamin precursors of NAD(+). C. glabrata salvage pathways defined in this article allow NAD(+) to be synthesized from three compounds - nicotinic acid (NA), nicotinamide (NAM) and nicotinamide riboside (NR). NA is salvaged through a functional Preiss-Handler pathway. NAM is first converted to NA by nicotinamidase and then salvaged by the Preiss-Handler pathway. Salvage of NR in C. glabrata occurs via two routes. The first, in which NR is phosphorylated by the NR kinase Nrk1, is independent of the Preiss-Handler pathway. The second is a novel pathway in which NR is degraded by the nucleosidases Pnp1 and Urh1, with a minor role for Meu1, and ultimately converted to NAD(+) via the nicotinamidase Pnc1 and the Preiss-Handler pathway. Using C. glabrata mutants whose growth depends exclusively on the external NA or NR supply, we also show that C. glabrata utilizes NR and to a lesser extent NA as NAD(+) sources during disseminated infection.

  18. Identification, Selection, and Enrichment of Cardiomyocyte Precursors

    Directory of Open Access Journals (Sweden)

    Bianca Ferrarini Zanetti

    2013-01-01

    Full Text Available The large-scale production of cardiomyocytes is a key step in the development of cell therapy and tissue engineering to treat cardiovascular diseases, particularly those caused by ischemia. The main objective of this study was to establish a procedure for the efficient production of cardiomyocytes by reprogramming mesenchymal stem cells from adipose tissue. First, lentiviral vectors expressing neoR and GFP under the control of promoters expressed specifically during cardiomyogenesis were constructed to monitor cell reprogramming into precardiomyocytes and to select cells for amplification and characterization. Cellular reprogramming was performed using 5′-azacytidine followed by electroporation with plasmid pOKS2a, which expressed Oct4, Sox2, and Klf4. Under these conditions, GFP expression began only after transfection with pOKS2a, and less than 0.015% of cells were GFP+. These GFP+ cells were selected for G418 resistance to find molecular markers of cardiomyocytes by RT-PCR and immunocytochemistry. Both genetic and protein markers of cardiomyocytes were present in the selected cells, with some variations among them. Cell doubling time did not change after selection. Together, these results indicate that enrichment with vectors expressing GFP and neoR under cardiomyocyte-specific promoters can produce large numbers of cardiomyocyte precursors (CMPs, which can then be differentiated terminally for cell therapy and tissue engineering.

  19. Earth Observing System precursor data sets

    Science.gov (United States)

    Mah, Grant R.; Eidenshink, Jeff C.; Sheffield, K. W.; Myers, Jeffrey S.

    1993-08-01

    The Land Processes Distributed Active Archive Center (DAAC) is archiving and processing precursor data from airborne and spaceborne instruments such as the thermal infrared multispectral scanner (TIMS), the NS-001 and thematic mapper simulators (TMS), and the advanced very high resolution radiometer (AVHRR). The instrument data are being used to construct data sets that simulate the spectral and spatial characteristics of the advanced spaceborne thermal emission and reflection radiometer (ASTER) and the moderate resolution imaging spectrometer (MODIS) flight instruments scheduled to be flown on the EOS-AM spacecraft. Ames Research Center has developed and is flying a MODIS airborne simulator (MAS), which provides coverage in both MODIS and ASTER bands. A simulation of an ASTER data set over Death Valley, California has been constructed using a combination of TMS and TIMS data, along with existing digital elevation models that were used to develop the topographic information. MODIS data sets are being simulated by using MAS for full-band site coverage at high resolution and AVHRR for global coverage at 1 km resolution.

  20. Enzymatic synthesis of vitamin B6 precursor

    Directory of Open Access Journals (Sweden)

    Prlainović Nevena Ž.

    2013-01-01

    Full Text Available 3-Cyano-4-ethoxymethyl-6-methyl-2-pyridone is an important precursor in the synthesis of vitamin B6, obtained in the addition reaction between 2-cyanoacetamide and 1-ethoxy-2,4-pentanedione catalyzed by lipase from Candida rugosa (triacylglycerol ester hydrolases, EC 3.1.1.3. This work shows new experimental data and mathematical modeling of lipase catalyzed synthesis of 3-cyano-4-ethoxymethyl-6-methyl-2-pyridone, starting from 1-ethoxy-2,4-pentanedione and 2-cyanoacetamide. Kinetic measurements were done at 50 oC with enzyme concentration of 1.2 % w/v. Experimental results were fitted with two kinetic models: the ordered bi-ter and ping-pong bi-ter model, and the initial rates of the reaction were found to correlate best with a ping-pong bi-ter mechanism with inhibition by 2-cyanoacetamide. Obtained specificity constants indicated that lipase from C. rugosa had higher affinity towards 1-ethoxy-2,4-pentanedione and less bulky substrates. [Projekat Ministarstva nauke Republike Srbije, br. 172013, br. III 46010 and br. 172049

  1. Precursors to suicidality and violence on antidepressants

    DEFF Research Database (Denmark)

    Bielefeldt, Andreas Ø; Danborg, Pia B; Gøtzsche, Peter C

    2016-01-01

    OBJECTIVE: To quantify the risk of suicidality and violence when selective serotonin and serotonin-norepinephrine reuptake inhibitors are given to adult healthy volunteers with no signs of a mental disorder. DESIGN: Systematic review and meta-analysis. MAIN OUTCOME MEASURE: Harms related to suici......OBJECTIVE: To quantify the risk of suicidality and violence when selective serotonin and serotonin-norepinephrine reuptake inhibitors are given to adult healthy volunteers with no signs of a mental disorder. DESIGN: Systematic review and meta-analysis. MAIN OUTCOME MEASURE: Harms related...... to suicidality, hostility, activation events, psychotic events and mood disturbances. SETTING: Published trials identified by searching PubMed and Embase and clinical study reports obtained from the European and UK drug regulators. PARTICIPANTS: Double-blind, placebo-controlled trials in adult healthy volunteers...... that reported on suicidality or violence or precursor events to suicidality or violence. RESULTS: A total of 5787 publications were screened and 130 trials fulfilled our inclusion criteria. The trials were generally uninformative; 97 trials did not report the randomisation method, 75 trials did not report any...

  2. Pair fireball precursors of neutron star mergers

    Science.gov (United States)

    Metzger, Brian D.; Zivancev, Charles

    2016-10-01

    If at least one neutron star (NS) is magnetized in a binary NS merger, then the orbital motion of the conducting companion during the final inspiral induces a strong voltage and current along the magnetic field lines connecting the NSs. If a modest fraction η of the extracted electromagnetic power extracted accelerates relativistic particles, the resulting gamma-ray emission a compact volume will result in the formation of an electron-positron pair fireball. Applying a steady-state pair wind model, we quantify the detectability of the precursor fireball with gamma-ray satellites. For η ˜ 1 the gamma-ray detection horizon of Dmax ≈ 10(Bd/1014 G)3/4 Mpc is much closer than the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO)/Virgo horizon of 200 Mpc, unless the NS surface magnetic field strength is very large, B_d ≲ 10^{15} G. Given the quasi-isotropic nature of the emission, mergers with weaker NS fields could contribute a nearby population of short gamma-ray bursts. Power not dissipated close to the binary is carried to infinity along the open field lines by a large-scale Poynting flux. Reconnection within this outflow, well outside of the pair photosphere, provides a potential site for non-thermal emission, such as a coherent millisecond radio burst.

  3. The Genetic Evolution of Melanoma from Precursor Lesions.

    Science.gov (United States)

    Shain, A Hunter; Yeh, Iwei; Kovalyshyn, Ivanka; Sriharan, Aravindhan; Talevich, Eric; Gagnon, Alexander; Dummer, Reinhard; North, Jeffrey; Pincus, Laura; Ruben, Beth; Rickaby, William; D'Arrigo, Corrado; Robson, Alistair; Bastian, Boris C

    2015-11-12

    The pathogenic mutations in melanoma have been largely catalogued; however, the order of their occurrence is not known. We sequenced 293 cancer-relevant genes in 150 areas of 37 primary melanomas and their adjacent precursor lesions. The histopathological spectrum of these areas included unequivocally benign lesions, intermediate lesions, and intraepidermal or invasive melanomas. Precursor lesions were initiated by mutations of genes that are known to activate the mitogen-activated protein kinase pathway. Unequivocally benign lesions harbored BRAF V600E mutations exclusively, whereas those categorized as intermediate were enriched for NRAS mutations and additional driver mutations. A total of 77% of areas of intermediate lesions and melanomas in situ harbored TERT promoter mutations, a finding that indicates that these mutations are selected at an unexpectedly early stage of the neoplastic progression. Biallelic inactivation of CDKN2A emerged exclusively in invasive melanomas. PTEN and TP53 mutations were found only in advanced primary melanomas. The point-mutation burden increased from benign through intermediate lesions to melanoma, with a strong signature of the effects of ultraviolet radiation detectable at all evolutionary stages. Copy-number alterations became prevalent only in invasive melanomas. Tumor heterogeneity became apparent in the form of genetically distinct subpopulations as melanomas progressed. Our study defined the succession of genetic alterations during melanoma progression, showing distinct evolutionary trajectories for different melanoma subtypes. It identified an intermediate category of melanocytic neoplasia, characterized by the presence of more than one pathogenic genetic alteration and distinctive histopathological features. Finally, our study implicated ultraviolet radiation as a major factor in both the initiation and progression of melanoma. (Funded by the National Institutes of Health and others.).

  4. NASAs Evolvable Mars Campaign: Mars Moons Robotic Precursor

    Science.gov (United States)

    Gernhardt, Michael L.; Abercromby, Andrew F. J.; Abell, Paul A.; Love, Stanley G.; Lee, David E.; Chappell, Steven P.; Howe, A. Scott; Friedensen, Victoria

    2015-01-01

    Human exploration missions to the moons of Mars are being considered within NASA's Evolvable Mars Campaign (EMC) as an intermediate step for eventual human exploration and pioneering of the surface of Mars. A range of mission architectures is being evaluated in which human crews would explore one or both moons for as little as 14 days or for as long as 500 days with a variety of orbital and surface habitation and mobility options being considered. Relatively little is known about the orbital, surface, or subsurface characteristics of either moon. This makes them interesting but challenging destinations for human exploration missions during which crewmembers must be able to effectively conduct scientific exploration without being exposed to undue risks due to radiation, dust, micrometeoroids, or other hazards. A robotic precursor mission to one or both moons will be required to provide data necessary for the design and operation of subsequent human systems and for the identification and prioritization of scientific exploration objectives. This paper identifies and discusses considerations for the design of such a precursor mission based on current human mission architectures. Objectives of a Mars' moon precursor in support of human missions are expected to include: 1) identifying hazards on the surface and the orbital environment at up to 50-km distant retrograde orbits; 2) collecting data on physical characteristics for planning of detailed human proximity and surface operations; 3) performing remote sensing and in situ science investigations to refine and focus future human scientific activities; and 4) prospecting for in situ resource utilization. These precursor objectives can be met through a combination or remote sensing (orbital) and in-situ (surface) measurements. Analysis of spacecraft downlink signals using radio science techniques would measure the moon's mass, mass distribution, and gravity field, which will be necessary to enable trajectory planning

  5. On important precursor of singular optics (tutorial)

    Science.gov (United States)

    Polyanskii, Peter V.; Felde, Christina V.; Bogatyryova, Halina V.; Konovchuk, Alexey V.

    2018-01-01

    The rise of singular optics is usually associated with the seminal paper by J. F. Nye and M. V. Berry [Proc. R. Soc. Lond. A, 336, 165-189 (1974)]. Intense development of this area of modern photonics has started since the early eighties of the XX century due to invention of the interfrence technique for detection and diagnostics of phase singularities, such as optical vortices in complex speckle-structured light fields. The next powerful incentive for formation of singular optics into separate area of the science on light was connectected with discovering of very practical technique for creation of singular optical beams of various kinds on the base of computer-generated holograms. In the eghties and ninetieth of the XX century, singular optics evolved, almost entirely, under the approximation of complete coherency of light field. Only at the threshold of the XXI century, it has been comprehended that the singular-optics approaches can be fruitfully expanded onto partially spatially coherent, partially polarized and polychromatic light fields supporting singularities of new kinds, that has been resulted in establishing of correlation singular optics. Here we show that correlation singular optics has much deeper roots, ascending to "pre-singular" and even pre-laser epoch and associated with the concept of partial coherence and polarization. It is remarcable that correlation singular optics in its present interpretation has forestalled the standard coherent singular optics. This paper is timed to the sixtieth anniversary of the most profound precursor of modern correlation singular optics [J. Opt. Soc. Am., 47, 895-902 (1957)].

  6. PRECOMBUSTION REMOVAL OF HAZARDOUS AIR POLLUTANT PRECURSORS

    Energy Technology Data Exchange (ETDEWEB)

    Unknown

    2000-10-09

    In response to growing environmental concerns reflected in the 1990 Clean Air Act Amendment (CAAA), the United States Department of Energy (DOE) sponsored several research and development projects in late 1995 as part of an initiative entitled Advanced Environmental Control Technologies for Coal-Based Power Systems. The program provided cost-shared support for research and development projects that could accelerate the commercialization of affordable, high-efficiency, low-emission, coal-fueled electric generating technologies. Clean coal technologies developed under this program would serve as prototypes for later generations of technologies to be implemented in the industrial sector. In order to identify technologies with the greatest potential for commercial implementation, projects funded under Phase I of this program were subject to competitive review by DOE before being considered for continuation funding under Phase II. One of the primary topical areas identified under the DOE initiative relates to the development of improved technologies for reducing the emissions of air toxics. Previous studies have suggested that many of the potentially hazardous air pollutant precursors (HAPPs) occur as trace elements in the mineral matter of run-of-mine coals. As a result, these elements have the potential to be removed prior to combustion at the mine site by physical coal cleaning processes (i.e., coal preparation). Unfortunately, existing coal preparation plants are generally limited in their ability to remove HAPPs due to incomplete liberation of the mineral matter and high organic associations of some trace elements. In addition, existing physical coal cleaning plants are not specifically designed or optimized to ensure that high trace element rejections may be achieved.

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

    Science.gov (United States)

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

    2015-01-01

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

  8. Dual role of melanins and melanin precursors as photoprotective and phototoxic agents: inhibition of ultraviolet radiation-induced lipid peroxidation

    Energy Technology Data Exchange (ETDEWEB)

    Schmitz, S.; Jimbow, K. [Alberta Univ., Edmonton, AB (Canada). Dept. of Dermatology and Cutaneous Sciences; Thomas, P.D.; Poznansky, M.J. [Alberta Univ., Edmonton, AB (Canada). Dept. of Physiology; Allen, T.M. [Alberta Univ., Edmonton, AB (Canada). Dept. of Pharmacology

    1995-06-01

    Ultraviolet radiation (UVR) is one of the risk factors for skin cancer and the main inducer of melanin pigmentation, the major protective mechanism of mammalian skin against radiation damage. The melanin pigments, eumelanin and pheomelanin, are likely to be important in protection against UVR, but their precursors are generally considered as phototoxic. The available data suggest DNA damage as the mechanism of phototoxicity. However, the effect of melanin precursors on membrane damage through lipid peroxidation, another important and probably more relevant (from the point-of-view of the melanosomal confinement of these molecules) mechanism of phototoxicity, is not known. As a model system for UVR-melanin-membrane interactions, we irradiated liposomes in the presence of eumelanin, pheomelanin and two of their major precursors, 5,6-dihydroxyindole (DHI) and 5-S-cysteinyldopa (SCD). The presence of the two melanin precursors substantially reduced the formation of lipid peroxidation products resulting from UVR exposure. The antioxidant activity of the melanin precursors was diminished under strong prooxidant conditions (presence of Fe{sub 3+}). These results suggest that melanin precursors may have an important role in the protection of skin against the harmful effects of UVR including photocarcinogenesis. (Author).

  9. MMPM - Mars MetNet Precursor Mission

    Science.gov (United States)

    Harri, A.-M.; Schmidt, W.; Pichkhadze, K.; Linkin, V.; Vazquez, L.; Uspensky, M.; Polkko, J.; Genzer, M.; Lipatov, A.; Guerrero, H.; Alexashkin, S.; Haukka, H.; Savijarvi, H.; Kauhanen, J.

    2008-09-01

    We are developing a new kind of planetary exploration mission for Mars - MetNet in situ observation network based on a new semi-hard landing vehicle called the Met-Net Lander (MNL). The eventual scope of the MetNet Mission is to deploy some 20 MNLs on the Martian surface using inflatable descent system structures, which will be supported by observations from the orbit around Mars. Currently we are working on the MetNet Mars Precursor Mission (MMPM) to deploy one MetNet Lander to Mars in the 2009/2011 launch window as a technology and science demonstration mission. The MNL will have a versatile science payload focused on the atmospheric science of Mars. Detailed characterization of the Martian atmospheric circulation patterns, boundary layer phenomena, and climatology cycles, require simultaneous in-situ measurements by a network of observation posts on the Martian surface. The scientific payload of the MetNet Mission encompasses separate instrument packages for the atmospheric entry and descent phase and for the surface operation phase. The MetNet mission concept and key probe technologies have been developed and the critical subsystems have been qualified to meet the Martian environmental and functional conditions. Prototyping of the payload instrumentation with final dimensions was carried out in 2003-2006.This huge development effort has been fulfilled in collaboration between the Finnish Meteorological Institute (FMI), the Russian Lavoschkin Association (LA) and the Russian Space Research Institute (IKI) since August 2001. Currently the INTA (Instituto Nacional de Técnica Aeroespacial) from Spain is also participating in the MetNet payload development. To understand the behavior and dynamics of the Martian atmosphere, a wealth of simultaneous in situ observations are needed on varying types of Martian orography, terrain and altitude spanning all latitudes and longitudes. This will be performed by the Mars MetNet Mission. In addition to the science aspects the

  10. Ethylene glycol assisted low-temperature synthesis of boron carbide powder from borate citrate precursors

    Directory of Open Access Journals (Sweden)

    Rafi-ud-din

    2014-09-01

    Full Text Available B4C powders were synthesized by carbothermal reduction of ethylene glycol (EG added borate citrate precursors, and effects of EG additions (0–50 mol% based on citric acid on the morphologies and yields of synthesized B4C powders were investigated. The conditions most suitable for the preparation of precursor were optimized and optimum temperature for precursor formation was 650 °C. EG additions facilitated low-temperature synthesis of B4C at 1350 °C, which was around 100–300 °C lower temperature compared to that without EG additions. The lowering of synthesis temperature was ascribed to the enlargement of interfacial area caused by superior homogeneity and dispersibility of precursors enabling the diffusion of reacting species facile. The 20% EG addition was optimal with free residual carbon lowered to 4%. For smaller EG additions, the polyhedral and rod-like particles of synthesized product co-existed. With higher EG additions, the morphology of synthesized product was transformed into needle and blade-like structure.

  11. Changes in Dissolved Organic Matter Composition and Disinfection Byproduct Precursors in Advanced Drinking Water Treatment Processes.

    Science.gov (United States)

    Phungsai, Phanwatt; Kurisu, Futoshi; Kasuga, Ikuro; Furumai, Hiroaki

    2018-03-20

    Molecular changes in dissolved organic matter (DOM) from treatment processes at two drinking water treatment plants in Japan were investigated using unknown screening analysis by Orbitrap mass spectrometry. DOM formulas with carbon, hydrogen and oxygen (CHO-DOM) were the most abundant class in water samples, and over half of them were commonly found at both plants. Among the treatment processes, ozonation induced the most drastic changes to DOM. Mass peak intensities of less saturated CHO-DOM (positive (oxygen subtracted double bond equivalent per carbon (DBE-O)/C)) decreased by ozonation, while more saturated oxidation byproducts (negative (DBE-O)/C) increased and new oxidation byproducts (OBPs) were detected. By Kendrick mass analysis, ozone reactions preferred less saturated CHO-DOM in the same alkylation families and produced more saturated alkylation families of OBPs. Following ozonation, biological activated carbon filtration effectively removed water samples where at least half were unknown. Putative precursors of these DBPs were determined based on electrophilic substitutions and addition reactions. Ozonation demonstrated better decomposition of addition reaction-type precursors than electrophilic substitution-type precursors; over half of both precursor types decreased during biological activated carbon filtration.

  12. Relative importance and interactions of furan precursors in sterilised, vegetable-based food systems.

    Science.gov (United States)

    Palmers, Stijn; Grauwet, Tara; Buvé, Carolien; Vanratingen, Koen; Kebede, Biniam T; Goos, Peter; Hendrickx, Marc E; Van Loey, Ann

    2016-01-01

    Mitigation strategies aimed at an intervention in the reaction pathways for furan formation (e.g., by adjusting precursor concentrations) might offer an additional route for furan reduction in sterilised, vegetable-based foods, without adverse effects on other food safety or quality attributes. As a first step towards product reformulation, the aim of the present study was to determine the relative importance and interactions of possible furan precursors in these types of foods. Based on an I-optimal experimental design, potato purée (naturally low in furan precursors) was spiked with known amounts of sugars, ascorbic acid, olive oil and β-carotene, and subjected to a thermal sterilisation. Significant correlations were observed between furan concentrations after thermal treatment and starting concentrations of ascorbic acid and monosaccharides (i.e., fructose and glucose). Ascorbic acid had a clear furan-reducing effect as an antioxidant by protecting (polyunsaturated) fatty acids against oxidative degradation. Fructose and glucose were the main precursors, which can most probably be attributed to their high, but realistic, concentrations in the product. The contributions of fatty acids and β-carotene were strongly dependent on redox interactions with other food constituents. In the same potato purées, only low concentrations (0-2 ng g(-1) purée) of 2-methylfuran were detected, indicating that the direct importance of the spiked food constituents as a precursor for methylfuran formation was rather small. Based on the results of this study, reducing the amount of monosaccharides or adjusting the redox conditions of the matrix are suggested as two possible approaches for furan mitigation on the product side.

  13. Terrorist Precursor Crimes: Issues and Options for Congress

    National Research Council Canada - National Science Library

    O'Neil, Siobhan

    2007-01-01

    ... not. Terrorist precursor crimes, offenses committed to facilitate a particular attack or promote a terrorist campaign's objectives, are thought to be often carried out far away from the primary theater...

  14. Precursor Parameter Identification for Insulated Gate Bipolar Transistor (IGBT) Prognostics

    Data.gov (United States)

    National Aeronautics and Space Administration — Precursor parameters have been identified to enable development of a prognostic approach for insulated gate bipolar transistors (IGBT). The IGBT were subjected to...

  15. On the possible involvement of bovine serum albumin precursor in ...

    Indian Academy of Sciences (India)

    biotin affinity chromatography and mass finger printing analysis technique, herein we report the identification of a 70 kDa size protein (bovine serum albumin precursor, BSAP) which binds strongly with lipoplexes and may play role in lipofection ...

  16. Unconsumed precursors and couplers after formation of oxidative hair dyes

    DEFF Research Database (Denmark)

    Rastogi, Suresh Chandra; Søsted, Heidi; Johansen, Jeanne Duus

    2006-01-01

    Contact allergy to hair dye ingredients, especially precursors and couplers, is a well-known entity among consumers having hair colouring done at home or at a hairdresser. The aim of the present investigation was to estimate consumer exposure to some selected precursors (p-phenylenediamine, toluene......-2,5-diamine) and couplers (3-aminophenol, 4-aminophenol, resorcinol) of oxidative hair dyes during and after hair dyeing. Concentrations of unconsumed precursors and couplers in 8 hair dye formulations for non-professional use were investigated, under the conditions reflecting hair dyeing. Oxidative...... hair dye formation in the absence of hair was investigated using 6 products, and 2 products were used for experimental hair dyeing. In both presence and absence of hair, significant amounts of unconsumed precursors and couplers remained in the hair dye formulations after final colour development. Thus...

  17. Synthesis of beta alumina from aluminum hydroxide and oxyhydroxide precursors

    CSIR Research Space (South Africa)

    Van Zyl, A

    1993-02-01

    Full Text Available Two aluminium oxyhydroxides, boehmite and pseudoboehmite, and two aluminium hydroxides, bayerite and gibbsite, have been investigated as precursors for the synthesis of the solid electrolyte, beta alumina. Reaction pathways and products have been...

  18. Nicotiana benthamiana as a production platform for artemisinin precursors

    OpenAIRE

    Nogueira, Marilise; Bouwmeester, Harro; Cankar, Katarina; Harpen, Teun W. J. M. van; Bosch, Dirk; Beekwilder, Jules

    2015-01-01

    BACKGROUND: Production of pharmaceuticals in plants provides an alternative for chemical synthesis, fermentation or natural sources. Nicotiana benthamiana is deployed at commercial scale for production of therapeutic proteins. Here the potential of this plant is explored for rapid production of precursors of artemisinin, a sesquiterpenoid compound that is used for malaria treatment. METHODOLOGY/PRINCIPAL FINDINGS: Biosynthetic genes leading to artemisinic acid, a precursor of artemisinin, wer...

  19. IL-9-Producing Mast Cell Precursors and Food Allergy

    Science.gov (United States)

    2017-10-01

    AWARD NUMBER: W81XWH-15-1-0517 TITLE: IL-9-Producing Mast Cell Precursors and Food Allergy PRINCIPAL INVESTIGATOR: Dr. Simon P. Hogan PhD...IL-9-Producing Mast Cell Precursors and Food Allergy 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Yui Hsi Wang, Sunil...for Public Release; Distribution Unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT: Food allergy is a harmful immune reaction driven by uncontrolled type-2

  20. Precursor salt assisted syntheses of high-index faceted concave hexagon and nanorod-like polyoxometalates

    Science.gov (United States)

    Pal, Jaya; Ganguly, Mainak; Mondal, Chanchal; Negishi, Yuichi; Pal, Tarasankar

    2014-12-01

    This paper describes an effective method for a precursor salt assisted fabrication and reshaping of two different polyoxometalates [(NH4)2Cu(MoO4)2 (ACM) and Cu3(MoO4)2(OH)2 (CMOH)] into five distinctive shapes through straightforward and indirect routes. Explicit regulation of the structural arrangements of ACM and CMOH has been studied in detail with altered precursor salt concentration employing our laboratory developed modified hydrothermal (MHT) method. Morphologically different ACM 3D architectures are evolved with higher molybdate concentration, whereas 1D growth of CMOH is observed with increased copper concentration. Interesting morphological transformation of the products has been accomplished employing one precursor salt at a time without using any other foreign reagent. It has been proven that large ACMs become labile in the presence of incoming Cu(ii) and NH4+ ions of the precursor salts. A new strategy for the conversion of faceted ACMs (hexagonal plate, circular plate and hollow flower) to exclusive CMOH nanorods through a Cu(ii) assisted reaction has been adopted. According to thermodynamic consideration, the synthesis of rare concave nanostructures with high index facet is still challenging due to their higher reactivity. In this study, concave hexagonal ACM with high index facet {hkl} has been successfully prepared for the first time from hexagonal ACM through simple etching with ammonium heptamolybdate (AHM), which is another precursor salt. Hexagonal ACM corrugates to a concave hexagon because of the higher reactivity of the {001} crystal plane than that of the {010} plane. It has been shown that high index facet exposed concave hexagonal ACM serves as a better catalyst for the photodegradation of dye than the other microstructures enclosed by low index facets.This paper describes an effective method for a precursor salt assisted fabrication and reshaping of two different polyoxometalates [(NH4)2Cu(MoO4)2 (ACM) and Cu3(MoO4)2(OH)2 (CMOH)] into

  1. Possible earthquake precursors revealed by LF radio signals

    Directory of Open Access Journals (Sweden)

    P. F. Biagi

    2001-01-01

    Full Text Available Among radio signals, low frequency (LF radio signals lie in the band between 30–300 kHz. Monitoring equipment with the ability to measure the electric strength of such signals at field sites, were designed and assembled in Italy. From 1993 onwards, the electric field strength of the MCO (216 kHz, France broadcasting station has been collecting measurements at two sites in central Italy that were chosen according to very low noise levels. At the end of 1996, radio signals from the CLT (189 kHz, Italy and CZE (270 kHz, Czech Republic broadcasting stations were included in the measurements. Meteorological data from central Italy were also collected over the same time period in order to study the influence of weather conditions on the experimental measurements. During the monitoring period, we observed some evident attenuation of the electric field strength in some of the radio signals at some of the receivers. The duration of the attenuation observed was several days, so it could possibly be related to particular meteorological conditions. On the other hand, this phenomenon might represent precursors of moderate (3.0 M 3.5 earthquakes that occurred near the receivers (within 50 km along the transmitter-receiver path. In this case, it is possible that the pre-seismic processes could have produced irregularities in the troposphere, such as ducts, reflecting layers and scattering zones, so that some local troposphere defocusing of the radio signals might have occurred. These observations were related only to moderate earthquakes and in these cases, suitable meteorological conditions were probably needed to observe the effect. Between February – March 1998, we observed at one measuring site, a significant increase in the CZE electric field strength. Unfortunately, we could not use the data of the other receiver in this case, due to frequent interruptions in the data set. The increase might have been a precursor of the strong seismic sequence (M = 5

  2. Ubiquilin 1 modulates amyloid precursor protein trafficking and Abeta secretion.

    Science.gov (United States)

    Hiltunen, Mikko; Lu, Alice; Thomas, Anne V; Romano, Donna M; Kim, Minji; Jones, Phill B; Xie, Zhongcong; Kounnas, Maria Z; Wagner, Steven L; Berezovska, Oksana; Hyman, Bradley T; Tesco, Giuseppina; Bertram, Lars; Tanzi, Rudolph E

    2006-10-27

    Ubiquilin 1 (UBQLN1) is a ubiquitin-like protein, which has been shown to play a central role in regulating the proteasomal degradation of various proteins, including the presenilins. We recently reported that DNA variants in UBQLN1 increase the risk for Alzheimer disease, by influencing expression of this gene in brain. Here we present the first assessment of the effects of UBQLN1 on the metabolism of the amyloid precursor protein (APP). For this purpose, we employed RNA interference to down-regulate UBQLN1 in a variety of neuronal and non-neuronal cell lines. We demonstrate that down-regulation of UBQLN1 accelerates the maturation and intracellular trafficking of APP, while not interfering with alpha-, beta-, or gamma-secretase levels or activity. UBQLN1 knockdown increased the ratio of APP mature/immature, increased levels of full-length APP on the cell surface, and enhanced the secretion of sAPP (alpha- and beta-forms). Moreover, UBQLN1 knockdown increased levels of secreted Abeta40 and Abeta42. Finally, employing a fluorescence resonance energy transfer-based assay, we show that UBQLN1 and APP come into close proximity in intact cells, independently of the presence of the presenilins. Collectively, our findings suggest that UBQLN1 may normally serve as a cytoplasmic "gatekeeper" that may control APP trafficking from intracellular compartments to the cell surface. These findings suggest that changes in UBQLN1 steady-state levels affect APP trafficking and processing, thereby influencing the generation of Abeta.

  3. Brain Region-Dependent Rejection of Neural Precursor Cell Transplants

    Directory of Open Access Journals (Sweden)

    Nina Fainstein

    2018-04-01

    Full Text Available The concept of CNS as an immune-privileged site has been challenged by the occurrence of immune surveillance and allogeneic graft rejection in the brain. Here we examined whether the immune response to allogeneic neural grafts is determined by the site of implantation in the CNS. Dramatic regional differences were observed between immune responses to allogeneic neural precursor/stem cell (NPC grafts in the striatum vs. the hippocampus. Striatal grafts were heavily infiltrated with IBA-1+ microglia/macrophages and CD3+ T cells and completely rejected. In contrast, hippocampal grafts exhibited milder IBA-1+ cell infiltration, were not penetrated efficiently by CD3+ cells, and survived efficiently for at least 2 months. To evaluate whether the hippocampal protective effect is universal, astrocytes were then transplanted. Allogeneic astrocyte grafts elicited a vigorous rejection process from the hippocampus. CD200, a major immune-inhibitory signal, plays an important role in protecting grafts from rejection. Indeed, CD200 knock out NPC grafts were rejected more efficiently than wild type NPCs from the striatum. However, lack of CD200 expression did not elicit NPC graft rejection from the hippocampus. In conclusion, the hippocampus has partial immune-privilege properties that are restricted to NPCs and are CD200-independent. The unique hippocampal milieu may be protective for allogeneic NPC grafts, through host-graft interactions enabling sustained immune-regulatory properties of transplanted NPCs. These findings have implications for providing adequate immunosuppression in clinical translation of cell therapy.

  4. Simultaneous removal of ammonia and N-nitrosamine precursors from high ammonia water by zeolite and powdered activated carbon.

    Science.gov (United States)

    Xue, Runmiao; Donovan, Ariel; Zhang, Haiting; Ma, Yinfa; Adams, Craig; Yang, John; Hua, Bin; Inniss, Enos; Eichholz, Todd; Shi, Honglan

    2018-02-01

    When adding sufficient chlorine to achieve breakpoint chlorination to source water containing high concentration of ammonia during drinking water treatment, high concentrations of disinfection by-products (DBPs) may form. If N-nitrosamine precursors are present, highly toxic N-nitrosamines, primarily N-nitrosodimethylamine (NDMA), may also form. Removing their precursors before disinfection should be a more effective way to minimize these DBPs formation. In this study, zeolites and activated carbon were examined for ammonia and N-nitrosamine precursor removal when incorporated into drinking water treatment processes. The test results indicate that Mordenite zeolite can remove ammonia and five of seven N-nitrosamine precursors efficiently by single step adsorption test. The practical applicability was evaluated by simulation of typical drinking water treatment processes using six-gang stirring system. The Mordenite zeolite was applied at the steps of lime softening, alum coagulation, and alum coagulation with powdered activated carbon (PAC) sorption. While the lime softening process resulted in poor zeolite performance, alum coagulation did not impact ammonia and N-nitrosamine precursor removal. During alum coagulation, more than 67% ammonia and 70%-100% N-nitrosamine precursors were removed by Mordenite zeolite (except 3-(dimethylaminomethyl)indole (DMAI) and 4-dimethylaminoantipyrine (DMAP)). PAC effectively removed DMAI and DMAP when added during alum coagulation. A combination of the zeolite and PAC selected efficiently removed ammonia and all tested seven N-nitrosamine precursors (dimethylamine (DMA), ethylmethylamine (EMA), diethylamine (DEA), dipropylamine (DPA), trimethylamine (TMA), DMAP, and DMAI) during the alum coagulation process. Copyright © 2017. Published by Elsevier B.V.

  5. Nicotinic acid, nicotinamide, and nicotinamide riboside: a molecular evaluation of NAD+ precursor vitamins in human nutrition.

    Science.gov (United States)

    Bogan, Katrina L; Brenner, Charles

    2008-01-01

    Although baseline requirements for nicotinamide adenine dinucleotide (NAD+) synthesis can be met either with dietary tryptophan or with less than 20 mg of daily niacin, which consists of nicotinic acid and/or nicotinamide, there is growing evidence that substantially greater rates of NAD+ synthesis may be beneficial to protect against neurological degeneration, Candida glabrata infection, and possibly to enhance reverse cholesterol transport. The distinct and tissue-specific biosynthetic and/or ligand activities of tryptophan, nicotinic acid, nicotinamide, and the newly identified NAD+ precursor, nicotinamide riboside, reviewed herein, are responsible for vitamin-specific effects and side effects. Because current data suggest that nicotinamide riboside may be the only vitamin precursor that supports neuronal NAD+ synthesis, we present prospects for human nicotinamide riboside supplementation and propose areas for future research.

  6. Simulating Precursor Radial Velocity Surveys for Future Exoplanet Direct Imaging Missions

    Science.gov (United States)

    Newman, Patrick; Plavchan, Peter; Crepp, Justin; Dulz, Shannon; Stark, Chris; Kane, Steven

    2018-01-01

    Future direct imaging missions such as WFIRST, HabEx, and LUVOIR aim to catalog and characterize Earth-analogs around nearby stars. The observing strategy and science yield and are strongly dependent on the frequency of Earth-like planets, and precursor knowledge of which stars specifically host suitable planetary systems. Ground-based radial velocity surveys can potentially identify targets and optimal observations times at a fraction of the cost of blind direct imaging surveys. We present the first phases of simulations of such a survey. We consider multiple telescopes, including their locations, weather conditions, observation time limitations, and instrument sensitivities. Multiple target selection optimization algorithms are considered. We calculate realistic radial velocity uncertainties based upon the known stellar properties of nearby direct imaging targets including effective temperature, metallicity, and surface gravity. We next inject and recover the masses and orbital parameters of real and simulated planets, estimating the effectiveness of a precursor radial velocity survey for direct imaging yield optimization.

  7. Search for enhancements due to pion condensation precursors in (p,p') reactions on 12C

    International Nuclear Information System (INIS)

    Escudie, J.; Austin, S.M.; Boudard, A.; Bruge, G.; Chaumeaux, A.; Farvacque, L.; Legrand, D.; Lugol, J.C.; Mayer, B.; Belery, P.; Debevec, P.T.; Delbar, T.; Deutsch, J.; Gregoire, G.; Prieels, R.; Cameron, J.M.; Glashausser, C.; Whitten, C.A.

    1981-01-01

    Cross sections for the 12 C(p,p') reaction leading to the 1 + states at 15.1 MeV(T = 1) and 12.7 MeV(T = 0) were measured at a bombarding energy of 402 MeV. These data, covering a range of momentum transfer q from 0.45 to 2.65 fm -1 (0.6 --3.7m/sub π/) provide a test of the effects, precursor to a pion condensate, predicted to be important for the T = 1 state near q = 2--3m/sub π/. The cross sections for the two 1 + states are very similar fro large q, perhaps indicating that the precursor effects are small

  8. Anhydride-functional silane immobilized onto titanium surfaces induces osteoblast cell differentiation and reduces bacterial adhesion and biofilm formation

    Energy Technology Data Exchange (ETDEWEB)

    Godoy-Gallardo, Maria, E-mail: maria.godoy.gallardo@upc.edu [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgy, Technical University of Catalonia (UPC), ETSEIB, Av. Diagonal 647, 08028 Barcelona (Spain); Centre for Research in NanoEngineering (CRNE) — UPC, C/ Pascual i Vila 15, 08028 Barcelona (Spain); Guillem-Marti, Jordi, E-mail: jordi.guillem.marti@upc.edu [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgy, Technical University of Catalonia (UPC), ETSEIB, Av. Diagonal 647, 08028 Barcelona (Spain); Centre for Research in NanoEngineering (CRNE) — UPC, C/ Pascual i Vila 15, 08028 Barcelona (Spain); Sevilla, Pablo, E-mail: psevilla@euss.es [Department of Mechanics, Escola Universitària Salesiana de Sarrià (EUSS), C/ Passeig de Sant Bosco, 42, 08017 Barcelona (Spain); Manero, José M., E-mail: jose.maria.manero@upc.edu [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgy, Technical University of Catalonia (UPC), ETSEIB, Av. Diagonal 647, 08028 Barcelona (Spain); Centre for Research in NanoEngineering (CRNE) — UPC, C/ Pascual i Vila 15, 08028 Barcelona (Spain); Gil, Francisco J., E-mail: francesc.xavier.gil@upc.edu [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgy, Technical University of Catalonia (UPC), ETSEIB, Av. Diagonal 647, 08028 Barcelona (Spain); Centre for Research in NanoEngineering (CRNE) — UPC, C/ Pascual i Vila 15, 08028 Barcelona (Spain); and others

    2016-02-01

    Bacterial infection in dental implants along with osseointegration failure usually leads to loss of the device. Bioactive molecules with antibacterial properties can be attached to titanium surfaces with anchoring molecules such as silanes, preventing biofilm formation and improving osseointegration. Properties of silanes as molecular binders have been thoroughly studied, but research on the biological effects of these coatings is scarce. The aim of the present study was to determine the in vitro cell response and antibacterial effects of triethoxysilypropyl succinic anhydride (TESPSA) silane anchored on titanium surfaces. X-ray photoelectron spectroscopy confirmed a successful silanization. The silanized surfaces showed no cytotoxic effects. Gene expression analyses of Sarcoma Osteogenic (SaOS-2) osteoblast-like cells cultured on TESPSA silanized surfaces reported a remarkable increase of biochemical markers related to induction of osteoblastic cell differentiation. A manifest decrease of bacterial adhesion and biofilm formation at early stages was observed on treated substrates, while favoring cell adhesion and spreading in bacteria–cell co-cultures. Surfaces treated with TESPSA could enhance a biological sealing on implant surfaces against bacteria colonization of underlying tissues. Furthermore, it can be an effective anchoring platform of biomolecules on titanium surfaces with improved osteoblastic differentiation and antibacterial properties. - Highlights: • TESPSA silane induces osteoblast differentiation. • TESPSA reduces bacterial adhesion and biofilm formation. • TESPSA is a promising anchoring platform of biomolecules onto titanium.

  9. Anhydride-functional silane immobilized onto titanium surfaces induces osteoblast cell differentiation and reduces bacterial adhesion and biofilm formation

    International Nuclear Information System (INIS)

    Godoy-Gallardo, Maria; Guillem-Marti, Jordi; Sevilla, Pablo; Manero, José M.; Gil, Francisco J.

    2016-01-01

    Bacterial infection in dental implants along with osseointegration failure usually leads to loss of the device. Bioactive molecules with antibacterial properties can be attached to titanium surfaces with anchoring molecules such as silanes, preventing biofilm formation and improving osseointegration. Properties of silanes as molecular binders have been thoroughly studied, but research on the biological effects of these coatings is scarce. The aim of the present study was to determine the in vitro cell response and antibacterial effects of triethoxysilypropyl succinic anhydride (TESPSA) silane anchored on titanium surfaces. X-ray photoelectron spectroscopy confirmed a successful silanization. The silanized surfaces showed no cytotoxic effects. Gene expression analyses of Sarcoma Osteogenic (SaOS-2) osteoblast-like cells cultured on TESPSA silanized surfaces reported a remarkable increase of biochemical markers related to induction of osteoblastic cell differentiation. A manifest decrease of bacterial adhesion and biofilm formation at early stages was observed on treated substrates, while favoring cell adhesion and spreading in bacteria–cell co-cultures. Surfaces treated with TESPSA could enhance a biological sealing on implant surfaces against bacteria colonization of underlying tissues. Furthermore, it can be an effective anchoring platform of biomolecules on titanium surfaces with improved osteoblastic differentiation and antibacterial properties. - Highlights: • TESPSA silane induces osteoblast differentiation. • TESPSA reduces bacterial adhesion and biofilm formation. • TESPSA is a promising anchoring platform of biomolecules onto titanium.

  10. Irradiation of human thymic stromal cells induces a diminution of T cell precursor proliferation

    Energy Technology Data Exchange (ETDEWEB)

    Bertho, J.M.; Van der Meeren, A. [CEA Fontenay-aux-Roses, 92 (France). Inst. de Protection et de Surete Nucleaire; Coulombel, L. [Institut Gustave Roussy, 94 - Villejuif (France)

    1997-03-01

    Very little is known concerning the effects of ionizing radiation on the supportive function of the thymic microenvironment in the regeneration of a fully competent T lymphocyte population after irradiation. The data available suggest that irradiation of the thymus may have short-term effects on the thymus and long-term effects on peripheral blood T lymphocytes. We have recently developed an in vitro model of thymic stromal cell cultures (TSCC). These TSCC contained 30-50% thymic epithelial cells (TEC), 50-70% fibro-blastoid cells (TF), and 1-5% macrophages and dendritic cells. This model was used to study effects of ionizing radiation on human thymic microenvironment. TSCC were irradiated at a dose of 10 Grays (gamma rays, {sup 60}Co source, dose rate 1 Gy/mn) or sham-irradiated. Sorted autologous T cell precursors were seeded onto TSCC 24 hours after irradiation. Proliferation of T cell precursors was assessed by numerating non-adherent cells in the supernatant of TSCC twice a week. Results show that irradiation of TSCC induced a diminution in the number of T cell precursor harvested from the cultures either in the presence or in the absence of interleukin-7 (IL-7) and stem cell factor (SCF). This diminished number of cells harvested appeared as early as day 4, and remained constant during 21-day culture period. The results showed that the number of stromal cells after irradiation remained constant until day 21. We have generated supernatants (SN) from irradiated TSCC in order to test the presence of negative regulators or the decrease of activating factors. Results showed that SN from irradiated TSCC were able to induce a decrease in the number of harvested T cells. Overall, the results provides the first direct demonstration that irradiation of thymic microenvironment induced modifications in its supportive function for T cell precursor proliferation. (N.C.)

  11. Fluid Mechanics of Lean Blowout Precursors in Gas Turbine Combustors

    Directory of Open Access Journals (Sweden)

    T. M. Muruganandam

    2012-03-01

    Full Text Available Understanding of lean blowout (LBO phenomenon, along with the sensing and control strategies could enable the gas turbine combustor designers to design combustors with wider operability regimes. Sensing of precursor events (temporary extinction-reignition events based on chemiluminescence emissions from the combustor, assessing the proximity to LBO and using that data for control of LBO has already been achieved. This work describes the fluid mechanic details of the precursor dynamics and the blowout process based on detailed analysis of near blowout flame behavior, using simultaneous chemiluminescence and droplet scatter observations. The droplet scatter method represents the regions of cold reactants and thus help track unburnt mixtures. During a precursor event, it was observed that the flow pattern changes significantly with a large region of unburnt mixture in the combustor, which subsequently vanishes when a double/single helical vortex structure brings back the hot products back to the inlet of the combustor. This helical pattern is shown to be the characteristic of the next stable mode of flame in the longer combustor, stabilized by double helical vortex breakdown (VBD mode. It is proposed that random heat release fluctuations near blowout causes VBD based stabilization to shift VBD modes, causing the observed precursor dynamics in the combustor. A complete description of the evolution of flame near the blowout limit is presented. The description is consistent with all the earlier observations by the authors about precursor and blowout events.

  12. Thioamides as false melanin precursors. Studies in murine melanomas

    Energy Technology Data Exchange (ETDEWEB)

    Olander, K.; Larsson, B.; Dencker, L. (Department of Toxicology, University of Uppsala, Sweden)

    1983-01-01

    Melanotic melanomas show a high rate of melanin synthesis. Foreign substances that are accepted as precursors in the formation of melanin may therefore be useful in the diagnosis and therapy of malignant melanotic melanomas, if labelled with suitable radionuclides. We have earlier reported that 2-thiouracil is incorporated in melanotic melanomas, apparently as a false melanin precursor. In the present study it is shown that methimazole and 5-iodo-2-thiouracil are as well accepted as melanin precursors. 5-Iodo-2-thiouracil is of special interest, since iodine has many clinically useful radioisotopes. The chemical properties that characterize substances which are incorporated as false precursors into melanin are discussed. A free sulfur ligand of the thioamides (2-thiouracil, 5-iodo-2-thiouracil, methimazole and thiourea are all incorporated into melanin) seems to be essential and the link between these substances and the melanin. Uracil (which lacks sulfur) and 2-benzylthiouracil (where the sulfur is blocked with a benzyl group) do not attach to melanin. Our conclusion therefore is that the thioureylene structure is the smallest common molecular fragment of the false melanin precursors.

  13. Accumulation of specific sterol precursors targets a MAP kinase cascade mediating cell–cell recognition and fusion

    Science.gov (United States)

    Weichert, Martin; Lichius, Alexander; Priegnitz, Bert-Ewald; Brandt, Ulrike; Gottschalk, Johannes; Nawrath, Thorben; Groenhagen, Ulrike; Read, Nick D.; Schulz, Stefan; Fleißner, André

    2016-01-01

    Sterols are vital components of eukaryotic cell membranes. Defects in sterol biosynthesis, which result in the accumulation of precursor molecules, are commonly associated with cellular disorders and disease. However, the effects of these sterol precursors on the metabolism, signaling, and behavior of cells are only poorly understood. In this study, we show that the accumulation of only ergosterol precursors with a conjugated double bond in their aliphatic side chain specifically disrupts cell–cell communication and fusion in the fungus Neurospora crassa. Genetically identical germinating spores of this fungus undergo cell–cell fusion, thereby forming a highly interconnected supracellular network during colony initiation. Before fusion, the cells use an unusual signaling mechanism that involves the coordinated and alternating switching between signal sending and receiving states of the two fusion partners. Accumulation of only ergosterol precursors with a conjugated double bond in their aliphatic side chain disrupts this coordinated cell–cell communication and suppresses cell fusion. These specific sterol precursors target a single ERK-like mitogen-activated protein (MAP) kinase (MAK-1)-signaling cascade, whereas a second MAP kinase pathway (MAK-2), which is also involved in cell fusion, is unaffected. These observations indicate that a minor specific change in sterol structure can exert a strong detrimental effect on a key signaling pathway of the cell, resulting in the absence of cell fusion. PMID:27708165

  14. Electron spectroscopic study of electronic and morphological modifications of the WSe2 surface induced by Rb adsorption

    International Nuclear Information System (INIS)

    Buck, Jens

    2010-01-01

    The rubidium-covered surface of the semiconducting transition metal dichalcogenide tungsten diselenide (WSe 2 ) is examined using photoelectron spectroscopy (PES) and photoemission electron microscopy (PEEM). Adsorbed Rb is known to induce a variety of effects in this system concerning electronic, structural, and mechanical properties. In this work, the surface potential created by charge transfer upon Rb deposition is examined in thermal equilibrium (band bending) and stationary non-equilibrium (surface photovoltage (SPV) effect), which is induced by the absorption of light. It is shown that combined measurements and numerical simulations of the SPV effect as a function of the photon flux can be exploited for the estimation of many material parameters of the system, especially of the unoccupied adsorbate state. Issues of extending a conventional photoelectron spectrometer setup by a secondary light source will be discussed in the context of simulations and calibration measurements. The customization of an existing theoretical model of the SPV effect for the WSe 2 : Rb system is introduced, and a comprehensive validation of the obtained predictions is given in the context of experimental data. In addition, the self-organized formation of Rb domains at room temperature was examined by application of spatially resolved XPS spectroscopy using the PEEM setup at the end station of beamline UE49/PGMa at the BESSY II synchrotron facility. From the obtained results, the arrangement of Rb in surface lattices can be concluded. Furthermore, an X-Ray absorption study of self-organized nanostructure networks, aiming at the chemical characterization, is presented. Based on the interpretation of the examined structures as tension-induced cracks, a statistical approach to analyzing large-scale features was pursued. First accordance with the predictions made by a primitive, mechanical model of crack creation developed here gives gives some evidence for the validity of the proposed

  15. Electron spectroscopic study of electronic and morphological modifications of the WSe{sub 2} surface induced by Rb adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Buck, Jens

    2010-07-20

    The rubidium-covered surface of the semiconducting transition metal dichalcogenide tungsten diselenide (WSe{sub 2}) is examined using photoelectron spectroscopy (PES) and photoemission electron microscopy (PEEM). Adsorbed Rb is known to induce a variety of effects in this system concerning electronic, structural, and mechanical properties. In this work, the surface potential created by charge transfer upon Rb deposition is examined in thermal equilibrium (band bending) and stationary non-equilibrium (surface photovoltage (SPV) effect), which is induced by the absorption of light. It is shown that combined measurements and numerical simulations of the SPV effect as a function of the photon flux can be exploited for the estimation of many material parameters of the system, especially of the unoccupied adsorbate state. Issues of extending a conventional photoelectron spectrometer setup by a secondary light source will be discussed in the context of simulations and calibration measurements. The customization of an existing theoretical model of the SPV effect for the WSe{sub 2}: Rb system is introduced, and a comprehensive validation of the obtained predictions is given in the context of experimental data. In addition, the self-organized formation of Rb domains at room temperature was examined by application of spatially resolved XPS spectroscopy using the PEEM setup at the end station of beamline UE49/PGMa at the BESSY II synchrotron facility. From the obtained results, the arrangement of Rb in surface lattices can be concluded. Furthermore, an X-Ray absorption study of self-organized nanostructure networks, aiming at the chemical characterization, is presented. Based on the interpretation of the examined structures as tension-induced cracks, a statistical approach to analyzing large-scale features was pursued. First accordance with the predictions made by a primitive, mechanical model of crack creation developed here gives gives some evidence for the validity of the

  16. Precursor B Cells Increase in the Lung during Airway Allergic Inflammation: A Role for B Cell-Activating Factor.

    Directory of Open Access Journals (Sweden)

    Konstantinos Samitas

    Full Text Available B cells, key cells in allergic inflammation, differentiate in the bone marrow and their precursors include pro-B, pre-B and immature B cells. Eosinophil progenitor cells increase in the lung after allergen exposure. However, the existence and possible role of B cell precursors in the lung during allergic inflammation remains elusive.A BALB/c mouse model of allergic airway inflammation was utilized to perform phenotypic and quantification analyses of pro-B and pre-B cells in the lung by flow cytometry. B cell maturation factors IL-7 and B cell-activating factor (BAFF and their receptors (CD127 and BAFFR, BCMA, TACI, respectively were also evaluated in the lung and serum. The effect of anti-BAFF treatment was investigated both in vivo (i.p. administration of BAFF-R-Ig fusion protein and in vitro (colony forming cell assay. Finally, BAFF levels were examined in the bronchoalveolar lavage (BAL of asthmatic patients and healthy controls.Precursor pro and pre-B cells increase in the lung after allergen exposure, proliferate in the lung tissue in vivo, express markers of chemotaxis (CCR10 and CXCR4 and co-stimulation (CD40, CD86 and are resistant to apoptosis (Bax. Precursor B cells express receptors for BAFF at baseline, while after allergen challenge both their ligand BAFF and the BCMA receptor expression increases in B cell precursors. Blocking BAFFR in the lung in vivo decreases eosinophils and proliferating precursor B cells. Blocking BAFFR in bone marrow cultures in vitro reduces pre-B colony formation units. BAFF is increased in the BAL of severe asthmatics.Our data support the concept of a BAFF-mediated role for B cell precursors in allergic airway inflammation.

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

    Science.gov (United States)

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

    2017-09-26

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

  18. PARTITIONING TUNGSTEN BETWEEN MATRIX PRECURSORS AND CHONDRULE PRECURSORS THROUGH RELATIVE SETTLING

    International Nuclear Information System (INIS)

    Hubbard, Alexander

    2016-01-01

    Recent studies of chondrites have found a tungsten isotopic anomaly between chondrules and matrix. Given the refractory nature of tungsten, this implies that W was carried into the solar nebula by at least two distinct families of pre-solar grains. The observed chondrule/matrix split requires that the distinct families were kept separate during the dust coagulation process, and that the two families of grain interacted with the chondrule formation mechanism differently. We take the co-existence of different families of solids in the same general orbital region at the chondrule-precursor size as given, and explore the requirements for them to have interacted with the chondrule formation process at significantly different rates. We show that this sorting of families of solids into chondrule- and matrix-destined dust had to have been at least as powerful a sorting mechanism as the relative settling of aerodynamically distinct grains at least two scale heights above the midplane. The requirement that the chondrule formation mechanism was correlated in some fashion with a dust-grain sorting mechanism argues strongly for spatially localized chondrule formation mechanisms such as turbulent dissipation in non-thermally ionized disk surface layers, and argues against volume-filling mechanisms such as planetesimal bow shocks.

  19. Measurements of ozone and its precursors in Beijing in summer

    Science.gov (United States)

    Lee, J. D.; Squires, F. A.; Dunmore, R.; Hamilton, J. F.; Hopkins, J. R.; Rickard, A. R.

    2017-12-01

    Over the past few years there have been substantial reductions in emission of primary pollutants (e.g. PM, NOx) in Beijing. However, levels of ozone (O3), which is produced from VOCs and NOxin the presence of sunlight, frequently break recommended exposure limits in Beijing and other large conurbations in China. In fact, it is suggested that ozone is likely to become the major air pollutant effecting human health in Beijing over the next 5-10 years. For 5 weeks in May and June 2017 O3 was measured, along with NOx, CO and a large range of VOCs (C2 - C13) at the Institute of Atmospheric Physics of the Chinese Academy of Sciences site, close to the 4th ring road in central Beijing. Elevated levels of O3 were regularly observed, with maximum concentrations of 180 ppbv. On 75% of days during this period, O3 breached the recommended WHO 8 hour exposure limit of 60 ppbv. Data will be presented showing the effect of different levels of precursor species and photolysis rates on O3. The peak concentration of O3 on each day seemed to have little correlation with NOx. Typically NO concentrations were elevated during the morning but often decreased to below 35oC meaning biogenic emissions also influenced the chemistry at the site, with several ppbv of isoprene measured during the afternoons. The importance of different VOCs for in-situ O3 formation is investigated using a simple steady state analysis of OH reactivity, along with a more detailed analysis using the Master Chemical Mechanism.

  20. APPLICATION OF STEM CELLS AND PRECURSOR CELLS FOR STIMULATION OF ORGAN REVASCULARIZATION AND REGENERATION

    Directory of Open Access Journals (Sweden)

    M. V. Eremeeva

    2010-01-01

    Full Text Available Different angiogenic factors induced angiogenesis stimulation in ischemic tissues stays in the focus of scientific research for long time. The key role in ischemic angiogenesis belongs to endothelial precursor cells, plenty of which are reserved in bone marrow. Resident endothelial precursor cells are also found in some tissues and in circulation. These cells are involved in neoangiogenesis as well. Theoretically, injection of exogeneous endothelial precusor cells might contribute to restoration of circulation in the ischemic organ. Various types of cells have been approved for regeneration stimulation in a number of experimental protocols. A various degree of improvement of myocardial contractive function has been obtained as a universal result of these investigations, though the mechanisms underlying observed effect remain evasive. The paper focuses on advantages and drawbacks of embryonic, hematopoetic and mesenhimal stem cells application for angiogenesis stimulation and organs and tissues regeneration. 

  1. Crystallization Kinetics in Liquid Crystals with Hexagonal Precursor Phases by Calorimetry

    Science.gov (United States)

    Padmaja, Sunkara; Ajita, Narayanan; Srinivasulu, Maddasani; Girish, Sriram Ramchandra; Pisipati, Venkata Gopala Krishna Murthy; Potukuchi, Dakshina Murthy

    2010-09-01

    Design and characterization of Schiff based liquid crystalline nO.m compounds exhibiting hexagonal smectic phases are reported. Crystallization kinetics investigations are carried out in the liquid crystals (LCs) exhibiting hexagonal ordered orthogonal and tilted precursor LC phases by calorimetry. The Avrami theory is referred and results are analyzed. Influence of molecular ordering, structure, and dimensionality of the LC precursor phase on kinetics is studied. Effect of shape and flexibility of the molecule for nucleation and growth processes is investigated. Varying rate of kinetics reflects upon the transit of the system from constant type to independent type of nucleation. The trends in the Avrami parameter b and exponent n suggest sporadic nucleation. Crystal growth is interpreted as heterogeneous permeation of layered domains (or aggregates) formed by needle shaped calamitic molecules. Calorimetric observations at different crystallization temperatures CT and hold time t infer diffusion mediated crystallization

  2. Crystallization kinetics in liquid crystals with hexagonal precursor phases by calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Padmaja, Sunkara; Ajita, Narayanan; Potukuchi, Dakshina Murthy [Dept. of Physics, Jawaharlal Nehru Technological Univ., Kakinada (India); Srinivasulu, Maddasani; Girish, Sriram Ramchandra [Liquid Crystal Research Centre, Koneru Lakshmaiah Coll. of Engineering, Vaddeswaram (India); Pisipati, Venkata Gopala Krishna Murthy [Dept. of Chemistry, Manipal Inst. of Tech. (India)

    2010-08-15

    Design and characterization of Schiff based liquid crystalline nO.m compounds exhibiting hexagonal smectic phases are reported. Crystallization kinetics investigations are carried out in the liquid crystals (LCs) exhibiting hexagonal ordered orthogonal and tilted precursor LC phases by calorimetry. The Avrami theory is referred and results are analyzed. Influence of molecular ordering, structure, and dimensionality of the LC precursor phase on kinetics is studied. Effect of shape and flexibility of the molecule for nucleation and growth processes is investigated. Varying rate of kinetics reflects upon the transit of the system from constant type to independent type of nucleation. The trends in the Avrami parameter b and exponent n suggest sporadic nucleation. Crystal growth is interpreted as heterogeneous permeation of layered domains (or aggregates) formed by needle shaped calamitic molecules. Calorimetric observations at different crystallization temperatures CT and hold time t infer diffusion mediated crystallization. (orig.)

  3. Synthesis and characterization of high-temperature ceramic YBCO nanostructures prepared from a novel precursor

    Directory of Open Access Journals (Sweden)

    M. Salavati-Niasari

    2011-01-01

    Full Text Available As a new precursor, [tris(2-hydroxyacetophenato triaqua(III], [Y(HAP3(H2O3]; complex was used in thermal decomposition process for the synthesis of rod-like high-temperature ceramic YBCO with length of about 320-350 nm and diameters 60–90 nm. The as-synthesized products were characterized by XRD, FT-IR, TEM, SEM and EDX analyses. The results showed that by using fine raw materials, the calcination temperature can be reduced to 870 ºC. It was found that this type of precursor have clearly effects on the size and morphology of product because the organic ligands around yttrium center act like a protecting agent to prevent agglomeration.

  4. Differentially activated macrophages orchestrate myogenic precursor cell fate during human skeletal muscle regeneration

    DEFF Research Database (Denmark)

    Saclier, Marielle; Yacoub-Youssef, Houda; Mackey, Abigail

    2013-01-01

    Macrophages (MPs) exert either beneficial or deleterious effects on tissue repair, depending on their activation/polarization state. They are crucial for adult skeletal muscle repair, notably by acting on myogenic precursor cells. However, these interactions have not been fully characterized. Here......, we explored both in vitro and in vivo, in human, the interactions of differentially activated MPs with myogenic precursor cells (MPCs) during adult myogenesis and skeletal muscle regeneration. We showed in vitro that through the differential secretion of cytokines and growth factors, proinflammatory...... MPs inhibited MPC fusion while anti-inflammatory MPs strongly promoted MPC differentiation by increasing their commitment into differentiated myocytes and the formation of mature myotubes. Furthermore, the in vivo time course of expression of myogenic and MP markers was studied in regenerating human...

  5. Precursor type affecting surface properties and catalytic activity of sulfated zirconia

    Directory of Open Access Journals (Sweden)

    Zarubica Aleksandra R.

    2007-01-01

    Full Text Available Zirconium-hydroxide precursor samples are synthesized from Zr-hydroxide, Zr-nitrate, and Zr-alkoxide, by precipitation/impregnation, as well as by a modified sol-gel method. Precursor samples are further sulphated for the intended SO4 2- content of 4 wt.%, and calcined at 500-700oC. Differences in precursors’ origin and calcination temperature induce the incorporation of SO4 2- groups into ZrO2 matrices by various mechanisms. As a result, different amounts of residual sulphates are coupled with other structural, as well as surface properties, resulting in various catalytic activities of sulphated zirconia samples. Catalyst activity and selectivity are a complex synergistic function of tetragonal phase fraction, sulphates contents, textural and surface characteristics. Superior activity of SZ of alkoxide origin can be explained by a beneficial effect of meso-pores owing to a better accommodation of coke deposits.

  6. Phenolic melanin precursors provide a rational approach to the design of antitumor agents for melanoma

    Energy Technology Data Exchange (ETDEWEB)

    Jimbow, K.; Miura, T.; Ito, S.; Ishikawa, K.

    1989-01-01

    A unique biological property of the melanocyte, melanin synthesis may permit a rational approach to design agents for better management of malignant melanoma. This in vivo and in vitro study examined the selective melanocytotoxicity and antimelanoma effects of phenolic compounds, cysteinylphenol (CP), cysteaminylphenol (CAP), and related compounds, and found (1) that both 4-S-CP and 4-S-CAP are melanin precursors, (2) that 4-S-CAP possesses a marked depigmenting potency with selective destruction of melanocytes in black follicles, and (3) a significant inhibition in the protein synthesis and tumor growth of B16 melanoma. Importantly, a whole body autoradiography indicated that these phenolic melanin precursors are selectively incorporated into melanoma tissues after i.p. administration.

  7. Microencapsulation of silicon nitride particles with yttria and yttria-alumina precursors

    International Nuclear Information System (INIS)

    Garg, A.K.; De Jonghe, L.C.

    1990-01-01

    Procedures are described to deposit uniform layers of yttria and yttria-alumina precursors on fine powders and whiskers of silicon nitride. The coatings were produced by aging at elevated temperatures aqueous systems containing the silicon nitride core particles, yttrium and aluminum nitrates, and urea. Optimum concentrations of the core particles, in relation to the reactants, were established to promote surface deposition of the oxide precursors. Polymeric dispersants were used effectively to prevent agglomeration of the solids during the microencapsulation process. The morphology of the powders was characterized using scanning and transmission electron microscopy. The mechanisms for the formation of the coated layers are discussed. A description is provided that allows qualitative assessment of the experimental factors that determine microencapsulation by a slurry method

  8. Evaluation of a Structural Model Relating Job Satisfaction, Organizational Commitment, and Precursors to Voluntary Turnover.

    Science.gov (United States)

    Lance, C E

    1991-01-01

    An integrative model of the determinants of overall job satisfaction, organizational commitment, and precursors to voluntary turnover was proposed. Job satisfaction and organizational commitment were proposed to arise from overlapping sets of work environment perceptions. A nonrecursive relationship was hypothesized between commitment and satisfaction. Affect (satisfaction and commitment) was proposed to mediate the effects of work environment perceptions on precursors to voluntary turnover. The model was evaluated using data obtained from 1,870 employees of a U.S. telecommunications firm. Hypotheses relating to determinants of commitment and turnover cognitions were largely supported. An asymmetric reciprocal relation was supported between overall job satisfaction and organizational commitment. Future research needs discussed include specification of different causal models for different forms of employee turnover.

  9. Isolation of Oct4-expressing extraembryonic endoderm precursor cell lines.

    Directory of Open Access Journals (Sweden)

    Bisrat G Debeb

    Full Text Available BACKGROUND: The extraembryonic endoderm (ExEn defines the yolk sac, a set of membranes that provide essential support for mammalian embryos. Recent findings suggest that the committed ExEn precursor is present already in the embryonic Inner Cell Mass (ICM as a group of cells that intermingles with the closely related epiblast precursor. All ICM cells contain Oct4, a key transcription factor that is first expressed at the morula stage. In vitro, the epiblast precursor is most closely represented by the well-characterized embryonic stem (ES cell lines that maintain the expression of Oct4, but analogous ExEn precursor cell lines are not known and it is unclear if they would express Oct4. METHODOLOGY/PRINCIPAL FINDINGS: Here we report the isolation and characterization of permanently proliferating Oct4-expressing rat cell lines ("XEN-P cell lines", which closely resemble the ExEn precursor. We isolated the XEN-P cell lines from blastocysts and characterized them by plating and gene expression assays as well as by injection into embryos. Like ES cells, the XEN-P cells express Oct4 and SSEA1 at high levels and their growth is stimulated by leukemia inhibitory factor, but instead of the epiblast determinant Nanog, they express the ExEn determinants Gata6 and Gata4. Further, they lack markers characteristic of the more differentiated primitive/visceral and parietal ExEn stages, but exclusively differentiate into these stages in vitro and contribute to them in vivo. CONCLUSIONS/SIGNIFICANCE: Our findings (i suggest strongly that the ExEn precursor is a self-renewable entity, (ii indicate that active Oct4 gene expression (transcription plus translation is part of its molecular identity, and (iii provide an in vitro model of early ExEn differentiation.

  10. Learning from Cancer Precursors | Center for Cancer Research

    Science.gov (United States)

    Cancers that are preceded by distinct nonmalignant lesions provide an opportunity to study cancer progression and develop early detection and intervention strategies. Multiple myeloma—a cancer of the bone marrow that originates in a type of white blood cell called plasma cells—is consistently preceded by one of two nonmalignant precursor diseases: monoclonal gammopathy of undetermined significance (MGUS) or smoldering myeloma. Ola Landgren, M.D., Ph.D., and Adam Waxman, B.A., of the CCR Medical Oncology Branch recently published a case presentation and review in JAMA that discusses current understanding of myeloma precursor diseases and future opportunities for improving personalized management of patients with these conditions.

  11. Differentiation of Mouse Embryonic Stem Cells into Ventral Foregut Precursors

    DEFF Research Database (Denmark)

    Rothová, Michaela; Hölzenspies, Jurriaan J; Livigni, Alessandra

    2016-01-01

    Anterior definitive endoderm (ADE), the ventral foregut precursor, is both an important embryonic signaling center and a unique multipotent precursor of liver, pancreas, and other organs. Here, a method is described for the differentiation of mouse embryonic stem cells (mESCs) to definitive...... endoderm with pronounced anterior character. ADE-containing cultures can be produced in vitro by suspension (embryoid body) culture or in a serum-free adherent monolayer culture. ESC-derived ADE cells are committed to endodermal fates and can undergo further differentiation in vitro towards ventral foregut...

  12. Unconsumed precursors and couplers after formation of oxidative hair dyes

    DEFF Research Database (Denmark)

    Rastogi, Suresh Chandra; Søsted, Heidi; Johansen, Jeanne Duus

    2006-01-01

    -2,5-diamine) and couplers (3-aminophenol, 4-aminophenol, resorcinol) of oxidative hair dyes during and after hair dyeing. Concentrations of unconsumed precursors and couplers in 8 hair dye formulations for non-professional use were investigated, under the conditions reflecting hair dyeing. Oxidative......, up to 1.1% p-phenylenediamine (PPD), 0.04% toluene-2,5-diamine, 0.02% 3-aminophenol and 0.02% resorcinol were found in the hair dye formulation after the required colour was developed. The consumers are thus exposed to precursors and couplers of oxidative hair dyes, both during and after hair dyeing...

  13. CHEMICAL VAPOUR DEPOSITION FROM A RADIATION-SENSITIVE PRECURSOR

    DEFF Research Database (Denmark)

    2017-01-01

    the substrate, wherein heating includes the transmission of electromagnetic heating radiation from a controllable radiative heat source through the reaction chamber towards the substrate, wherein the radiative heat source is controlled to provide electromagnetic radiation as one or more heating pulses, each...... heating pulse followed by an idle period; (iii) during at least one of the idle periods, providing a pressure pulse of precursor substance inside the reaction chamber by feeding at least one precursor substance to the reaction chamber so as to establish a reaction partial pressure for thin film deposition...

  14. Secretory clusterin inhibits osteoclastogenesis by attenuating M-CSF-dependent osteoclast precursor cell proliferation

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Bongkun; Kang, Soon-Suk [Department of Biomedical Sciences, University of Ulsan College of Medicine, Asan Medical Center, Seoul 138-736 (Korea, Republic of); Kang, Sang-Wook [Department of Biomedical Sciences, University of Ulsan College of Medicine, Asan Medical Center, Seoul 138-736 (Korea, Republic of); Department of Anatomy and Cell Biology, Cell Dysfunction Research Center and BMIT, University of Ulsan College of Medicine, Asan Medical Center, Seoul 138-736 (Korea, Republic of); Min, Bon-Hong [Department of Pharmacology, Korea University College of Medicine, Seoul 136-705 (Korea, Republic of); Lee, Eun-Jin; Song, Da-Hyun; Kim, Sang-Min [Department of Biomedical Sciences, University of Ulsan College of Medicine, Asan Medical Center, Seoul 138-736 (Korea, Republic of); Song, Youngsup [Department of Biomedical Sciences, University of Ulsan College of Medicine, Asan Medical Center, Seoul 138-736 (Korea, Republic of); Department of Anatomy and Cell Biology, Cell Dysfunction Research Center and BMIT, University of Ulsan College of Medicine, Asan Medical Center, Seoul 138-736 (Korea, Republic of); Yoon, Seung-Yong [Department of Anatomy and Cell Biology, Cell Dysfunction Research Center and BMIT, University of Ulsan College of Medicine, Asan Medical Center, Seoul 138-736 (Korea, Republic of); Chang, Eun-Ju, E-mail: ejchang@amc.seoul.kr [Department of Biomedical Sciences, University of Ulsan College of Medicine, Asan Medical Center, Seoul 138-736 (Korea, Republic of); Department of Anatomy and Cell Biology, Cell Dysfunction Research Center and BMIT, University of Ulsan College of Medicine, Asan Medical Center, Seoul 138-736 (Korea, Republic of)

    2014-07-18

    Highlights: • We describe the expression and secretion of clusterin in osteoclasts. • Endogenous clusterin deficiency does not affect osteoclast formation. • Exogenous treatment with secretory clusterin decreases osteoclast differentiation. • Secretory clusterin attenuates osteoclast precursor cell proliferation by inhibiting M-CSF-mediated ERK activation. - Abstract: Secretory clusterin (sCLU)/apolipoprotein J is a multifunctional glycoprotein that is ubiquitously expressed in various tissues. Reduced sCLU in the joints of patients with bone erosive disease is associated with disease activity; however, its exact role has yet to be elucidated. Here, we report that CLU is expressed and secreted during osteoclastogenesis in mouse bone marrow-derived macrophages (BMMs) that are treated with receptor activator of nuclear factor kappa-B ligand (RANKL) and macrophage colony-stimulating factor (M-CSF). CLU-deficient BMMs obtained from CLU{sup −/−} mice exhibited no significant alterations in OC differentiation in comparison with BMMs obtained from wild-type mice. In contrast, exogenous sCLU treatment significantly inhibited OC formation in both BMMs and OC precursor cultures. The inhibitory effect of sCLU was more prominent in BMMs than OC precursor cultures. Interestingly, treating BMMs with sCLU decreased the proliferative effects elicited by M-CSF and suppressed M-CSF-induced ERK activation of OC precursor cells without causing apoptotic cell death. This study provides the first evidence that sCLU reduces OC formation by inhibiting the actions of M-CSF, thereby suggesting its protective role in bone erosion.

  15. Differential and directional estrogenic signaling pathways induced by enterolignans and their precursors.

    Directory of Open Access Journals (Sweden)

    Yun Zhu

    Full Text Available Mammalian lignans or enterolignans are metabolites of plant lignans, an important category of phytochemicals. Although they are known to be associated with estrogenic activity, cell signaling pathways leading to specific cell functions, and especially the differences among lignans, have not been explored. We examined the estrogenic activity of enterolignans and their precursor plant lignans and cell signaling pathways for some cell functions, cell cycle and chemokine secretion. We used DNA microarray-based gene expression profiling in human breast cancer MCF-7 cells to examine the similarities, as well as the differences, among enterolignans, enterolactone and enterodiol, and their precursors, matairesinol, pinoresinol and sesamin. The profiles showed moderate to high levels of correlation (R values: 0.44 to 0.81 with that of estrogen (17β-estradiol or E2. Significant correlations were observed among lignans (R values: 0.77 to 0.97, and the correlations were higher for cell functions related to enzymes, signaling, proliferation and transport. All the enterolignans/precursors examined showed activation of the Erk1/2 and PI3K/Akt pathways, indicating the involvement of rapid signaling through the non-genomic estrogen signaling pathway. However, when their effects on specific cell functions, cell cycle progression and chemokine (MCP-1 secretion were examined, positive effects were observed only for enterolactone, suggesting that signals are given in certain directions at a position closer to cell functions. We hypothesized that, while estrogen signaling is initiated by the enterolignans/precursors examined, their signals are differentially and directionally modulated later in the pathways, resulting in the differences at the cell function level.

  16. Non-PGM cathode catalysts for fuel cell application derived from heat treated heteroatomic amines precursors

    Energy Technology Data Exchange (ETDEWEB)

    Serov, Alexey; Halevi, Barr; Artyushkova, Kateryna; Atanassov, Plamen B; Martinez, Ulises A

    2017-04-25

    A method of preparing M-N--C catalysts utilizing a sacrificial support approach and inexpensive and readily available polymer precursors as the source of nitrogen and carbon is disclosed. Exemplary polymer precursors include non-porphyrin precursors with no initial catalytic activity. Examples of suitable non-catalytic non-porphyrin precursors include, but are not necessarily limited to low molecular weight precursors that form complexes with iron such as 4-aminoantipirine, phenylenediamine, hydroxysuccinimide, ethanolamine, and the like.

  17. Inhibition of glycogen synthase kinase-3 enhances the differentiation and reduces the proliferation of adult human olfactory epithelium neural precursors

    International Nuclear Information System (INIS)

    Manceur, Aziza P.; Tseng, Michael; Holowacz, Tamara; Witterick, Ian; Weksberg, Rosanna; McCurdy, Richard D.; Warsh, Jerry J.; Audet, Julie

    2011-01-01

    The olfactory epithelium (OE) contains neural precursor cells which can be easily harvested from a minimally invasive nasal biopsy, making them a valuable cell source to study human neural cell lineages in health and disease. Glycogen synthase kinase-3 (GSK-3) has been implicated in the etiology and treatment of neuropsychiatric disorders and also in the regulation of murine neural precursor cell fate in vitro and in vivo. In this study, we examined the impact of decreased GSK-3 activity on the fate of adult human OE neural precursors in vitro. GSK-3 inhibition was achieved using ATP-competitive (6-bromoindirubin-3'-oxime and CHIR99021) or substrate-competitive (TAT-eIF2B) inhibitors to eliminate potential confounding effects on cell fate due to off-target kinase inhibition. GSK-3 inhibitors decreased the number of neural precursor cells in OE cell cultures through a reduction in proliferation. Decreased proliferation was not associated with a reduction in cell survival but was accompanied by a reduction in nestin expression and a substantial increase in the expression of the neuronal differentiation markers MAP1B and neurofilament (NF-M) after 10 days in culture. Taken together, these results suggest that GSK-3 inhibition promotes the early stages of neuronal differentiation in cultures of adult human neural precursors and provide insights into the mechanisms by which alterations in GSK-3 signaling affect adult human neurogenesis, a cellular process strongly suspected to play a role in the etiology of neuropsychiatric disorders.

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

    Science.gov (United States)

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

    2010-11-01

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

  19. Embryonic cerebrospinal fluid activates neurogenesis of neural precursors within the subventricular zone of the adult mouse brain.

    Science.gov (United States)

    Carnicero, E; Alonso, M I; Carretero, R; Lamus, F; Moro, J A; de la Mano, A; Fernández, J M F; Gato, A

    2013-01-01

    There is a nondeveloped neurogenic potential in the adult mammalian brain, which could be the basis for neuroregenerative strategies. Many research efforts have been made to understand the control mechanisms which regulate the transition from a neural precursor to a neuron in the adult brain. Embryonic cerebrospinal fluid (CSF) is a complex fluid which has been shown to play a key role in neural precursor behavior during development, working as a powerful neurogenic inductor. We tested if the neurogenic properties of embryonic CSF are able to increase the neurogenic activity of neuronal precursors from the subventricular zone (SVZ) in the brains of adult mice. Our results show that mouse embryonic CSF significantly increases the neurogenic activity in precursor cells from adult brain SVZ. This intense neurogenic effect was specific for embryonic CSF and was not induced by adult CSF. Embryonic CSF is a powerful neurogenesis inductor in homologous neuronal precursors in the adult brain. This property of embryonic CSF could be a useful tool in neuroregeneration strategies.

  20. Effect of variation of precursor concentration on structural ...

    Indian Academy of Sciences (India)

    (0·01, 0·02 and 0·03 M) on the structural, microstructural, optical and gas sensing properties of TiO2 thin films. Titanium dioxide (TiO2) films ... demand and emerging challenges for gas sensors to monitor. LPG (Patil et al 2006, 2010; ..... Buechler K J, Noble R D, Koval C A and Jacoby W A 1999 Ind. Eng. Chem. Res. 38 892 ...

  1. GDNF facilitates differentiation of the adult dentate gyrus-derived neural precursor cells into astrocytes via STAT3

    Energy Technology Data Exchange (ETDEWEB)

    Boku, Shuken, E-mail: shuboku@med.hokudai.ac.jp [Department of Psychiatry, Hokkaido University Graduate School of Medicine, Sapporo (Japan); Nakagawa, Shin [Department of Psychiatry, Hokkaido University Graduate School of Medicine, Sapporo (Japan); Takamura, Naoki [Pharmaceutical Laboratories, Dainippon Sumitomo Pharma Co. Ltd., Osaka (Japan); Kato, Akiko [Department of Psychiatry, Hokkaido University Graduate School of Medicine, Sapporo (Japan); Takebayashi, Minoru [Department of Psychiatry, National Hospital Organization Kure Medical Center, Kure (Japan); Hisaoka-Nakashima, Kazue [Department of Pharmacology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima (Japan); Omiya, Yuki; Inoue, Takeshi; Kusumi, Ichiro [Department of Psychiatry, Hokkaido University Graduate School of Medicine, Sapporo (Japan)

    2013-05-17

    Highlights: •GDNF has no effect on ADP proliferation and apoptosis. •GDNF increases ADP differentiation into astrocyte. •A specific inhibitor of STAT3 decreases the astrogliogenic effect of GDNF. •STAT3 knockdown by lentiviral shRNA vector also decreases the astrogliogenic effect of GDNF. •GDNF increases the phosphorylation of STAT3. -- Abstract: While the pro-neurogenic actions of antidepressants in the adult hippocampal dentate gyrus (DG) are thought to be one of the mechanisms through which antidepressants exert their therapeutic actions, antidepressants do not increase proliferation of neural precursor cells derived from the adult DG. Because previous studies showed that antidepressants increase the expression and secretion of glial cell line-derived neurotrophic factor (GDNF) in C6 glioma cells derived from rat astrocytes and GDNF increases neurogenesis in adult DG in vivo, we investigated the effects of GDNF on the proliferation, differentiation and apoptosis of cultured neural precursor cells derived from the adult DG. Data showed that GDNF facilitated the differentiation of neural precursor cells into astrocytes but had no effect on their proliferation or apoptosis. Moreover, GDNF increased the phosphorylation of STAT3, and both a specific inhibitor of STAT3 and lentiviral shRNA for STAT3 decreased their differentiation into astrocytes. Taken together, our findings suggest that GDNF facilitates astrogliogenesis from neural precursor cells in adult DG through activating STAT3 and that this action might indirectly affect neurogenesis.

  2. GDNF facilitates differentiation of the adult dentate gyrus-derived neural precursor cells into astrocytes via STAT3

    International Nuclear Information System (INIS)

    Boku, Shuken; Nakagawa, Shin; Takamura, Naoki; Kato, Akiko; Takebayashi, Minoru; Hisaoka-Nakashima, Kazue; Omiya, Yuki; Inoue, Takeshi; Kusumi, Ichiro

    2013-01-01

    Highlights: •GDNF has no effect on ADP proliferation and apoptosis. •GDNF increases ADP differentiation into astrocyte. •A specific inhibitor of STAT3 decreases the astrogliogenic effect of GDNF. •STAT3 knockdown by lentiviral shRNA vector also decreases the astrogliogenic effect of GDNF. •GDNF increases the phosphorylation of STAT3. -- Abstract: While the pro-neurogenic actions of antidepressants in the adult hippocampal dentate gyrus (DG) are thought to be one of the mechanisms through which antidepressants exert their therapeutic actions, antidepressants do not increase proliferation of neural precursor cells derived from the adult DG. Because previous studies showed that antidepressants increase the expression and secretion of glial cell line-derived neurotrophic factor (GDNF) in C6 glioma cells derived from rat astrocytes and GDNF increases neurogenesis in adult DG in vivo, we investigated the effects of GDNF on the proliferation, differentiation and apoptosis of cultured neural precursor cells derived from the adult DG. Data showed that GDNF facilitated the differentiation of neural precursor cells into astrocytes but had no effect on their proliferation or apoptosis. Moreover, GDNF increased the phosphorylation of STAT3, and both a specific inhibitor of STAT3 and lentiviral shRNA for STAT3 decreased their differentiation into astrocytes. Taken together, our findings suggest that GDNF facilitates astrogliogenesis from neural precursor cells in adult DG through activating STAT3 and that this action might indirectly affect neurogenesis

  3. Precursors in detonations in porous explosives

    International Nuclear Information System (INIS)

    Spaulding, R.L. Jr.

    1981-01-01

    Photographs of detonation waves in low-density HMX and PETN, made with an image-intensifier camera, show a brilliant band of light in front of the pressure jump. The radiation temperature is estimated to be 12,000 to 14,000 0 K. The spectrum of this light is continuous. A quartz gauge shows a gradual buildup of pressure from the material producing the light. The material has little effect on the propagation of detonation. Further observations, using pellets of plastic-bonded HMX and single crystals of PETN, show that the material thrown off the free surface is transparent, with a leading edge moving at approximately 20 mm/μs. Collision of this material with polymethyl methacrylate (PMMA) produces a brilliant light with a spectrum that is initially a narrow H/sub α/ line. Quartz gauges measure the rate of pessure buildup of this material

  4. Cancer precursors epidemiology, detection, and prevention

    CERN Document Server

    Rohan, Thomas

    2002-01-01

    Dramatic advances in our understanding of cancer causation have come from epidemiologic and laboratory research, particularly over the past two decades. These developments have included a broadening interest in the critical events that take place during the early stages of the dynamic multistep process leading to - vasive cancer. Increasingly, cancer epidemiologists are pursuing research into the origins and natural history of premalignant lesions, including intermediate or surrogate endpoints, a trend - celerated by the development of molecular technologies that are revolutionizing our understanding of the transformation of normal to malignant cells. There seems little doubt that this emerging knowledge will provide further insights not only into carcinogenic processes, but also into more sensitive methods of early detection and more effective means of prevention. In this book, Drs. Franco and Rohan have succeeded in prep- ing a comprehensive, timely, and critical review of the substantial progress that has ...

  5. Pre-hydrolysed ethyl silicate as an alternative precursor for SiO{sub 2}-coated carbon nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Barrena, M.I., E-mail: ibarrena@quim.ucm.es [Departamento de Ciencia de los Materiales e Ingenieria Metalurgica, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, Av. Complutense s/n, 28040 Madrid (Spain); Gomez de Salazar, J.M.; Soria, A.; Matesanz, L. [Departamento de Ciencia de los Materiales e Ingenieria Metalurgica, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, Av. Complutense s/n, 28040 Madrid (Spain)

    2011-11-15

    This work reported basically aims at understanding the extent of SiO{sub 2}-coated carbon nanofibers using two different sol-gel precursors for the silicate glass. The silicate precursors employed were tetraethoxysilane (TEOS) and pre-hydrolysed ethyl silicate. The first route consisted in an acid hydrolysis and polycondensation of the TEOS and the second one in a polycondensation of the pre-hydrolysed ethyl silicate. The techniques of Fourier Infra Red spectroscopy, thermogravimetric analysis, scanning electron microscopy and X-ray diffraction were used to characterize the materials obtained. Both kinds of SiO{sub 2} precursor can coat the CNF effectively. However, the use of pre-hydrolysed ethyl silicate (faster gelation times and higher surface areas) can be considered a low-cost and facile alternative with respect to the use of TEOS, to obtain industrially silica-coated carbon nanofibers.

  6. Analytical and preparative resolution of enantiomers of prostaglandin precursors and prostaglandins by liquid chromatography on derivatized cellulose chiral stationary phases.

    Science.gov (United States)

    Miller, L; Weyker, C

    1990-07-06

    Analytical methods were developed for the separation of the enantiomers of four cyclopentenone precursors of prostaglandins. The resolution obtained is correlated with the chemical environment around the chiral center of the cyclopentenones. The analytical methods were scaled up to preparative loadings and the chromatographic parameters were varied to determine their effect on the preparative separations. The correlation between analytical resolution and preparative resolution was also investigated. In addition to the precursors, the preparative resolution of the enantiomers of a synthetic prostaglandin analogue was investigated.

  7. Theoretical study on the initial reaction mechanisms of ansa-metallocene zirconium precursor on hydroxylated Si(1 0 0) surface.

    Science.gov (United States)

    Zhou, Guangfen; Ren, Jie; Zhang, Shaowen

    2016-05-01

    The initial reaction mechanisms for depositing ZrO2 thin films using ansa-metallocene zirconium (Cp2CMe2)ZrMe2 precursor were studied by density functional theory (DFT) calculations. The (Cp2CMe2)ZrMe2 precursor could be absorbed on the hydroxylated Si(1 0 0) surface via physisorption. Possible reaction pathways of (Cp2CMe2)ZrMe2 were proposed. For each reaction, the activation energies and reaction energies were compared, and stationary points along the reaction pathways were shown. In addition, the influence of dispersion effects on the reactions was evaluated by non-local dispersion corrected DFT calculations.

  8. Students' Perception of Continuous Assessment as a Precursor to ...

    African Journals Online (AJOL)

    The research was undertaken to assess students' perception of continuous assessment as a precursor to academic performance among junior secondary school students in Ogun state. Five hundred and five students who were randomly selected divided into two groups were involved in the study. Three null hypotheses ...

  9. Influence of hydrophobic characteristic of organo-modified precursor ...

    Indian Academy of Sciences (India)

    Influence of hydrophobic characteristic of organo-modified precursor on wettability of silica film ... 202, 6th district, P.O. Box 35-174, 060021 Bucharest, Romania; Faculty of Physics, University of Bucharest, 3Nano-SAE Research Centre, P.O. Box MG-38, 077125 Bucharest-Magurele, Romania; Faculty of Chemistry, ...

  10. Low temperature catalyst-assisted pyrolysis of polymer precursors to ...

    Indian Academy of Sciences (India)

    2017-11-15

    Nov 15, 2017 ... https://doi.org/10.1007/s12034-017-1495-9. Low temperature catalyst-assisted pyrolysis of polymer precursors to carbon. RAMYA ARAGA, SURESH KALI and CHANDRA S SHARMA. ∗. Creative and Advanced Research Based On Nanomaterials (CARBON) Laboratory, Department of Chemical ...

  11. Intercalation chemistry of layered zeolite precursor IPC-1P

    Czech Academy of Sciences Publication Activity Database

    Mazur, Michal; Eliášová, Pavla; Roth, Wieslaw Jerzy; Čejka, Jiří

    2014-01-01

    Roč. 227, MAY 2014 (2014), s. 37-44 ISSN 0920-5861 R&D Projects: GA ČR(CZ) GAP106/12/0189 Institutional support: RVO:61388955 Keywords : UTL germanosilicate * IPC-1P layered precursor * Two-dimensional zeolites Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.893, year: 2014

  12. Intermediate obtained from photoionization, serving as precursor for ...

    African Journals Online (AJOL)

    In this article, we have introduced an intermediate benzyl carbocation (formed as a result of photoionization) which serves as precursor for the synthesis of Schiff's base. Lifetimes of many carbocations were determined from our laboratory. During the determination of the lifetimes, our endeavor was to obtain a carbocation ...

  13. College Student Stress: A Predictor of Eating Disorder Precursor Behaviors

    Science.gov (United States)

    Shelton, Virginia L.; Valkyrie, Karena T.

    2010-01-01

    Eating disorders are compulsive behaviors that can consume a person's life to the point of becoming life threatening. Previous research found stress associated with eating disorders. College can be a stressful time. If stress predicted precursor behaviors to eating disorders, then counselors would have a better chance to help students sooner. This…

  14. Manganite perovskite ceramics, their precursors and methods for forming

    Science.gov (United States)

    Payne, David Alan; Clothier, Brent Allen

    2015-03-10

    Disclosed are a variety of ceramics having the formula Ln.sub.1-xM.sub.xMnO.sub.3, where 0.Itoreq.x.Itoreq.1 and where Ln is La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu or Y; M is Ca, Sr, Ba, Cd, or Pb; manganite precursors for preparing the ceramics; a method for preparing the precursors; and a method for transforming the precursors into uniform, defect-free ceramics having magnetoresistance properties. The manganite precursors contain a sol and are derived from the metal alkoxides: Ln(OR).sub.3, M(OR).sub.2 and Mn(OR).sub.2, where R is C.sub.2 to C.sub.6 alkyl or C.sub.3 to C.sub.9 alkoxyalkyl, or C.sub.6 to C.sub.9 aryl. The preferred ceramics are films prepared by a spin coating method and are particularly suited for incorporation into a device such as an integrated circuit device.

  15. Methionine as a Precursor of Ethylene—Commentary

    Science.gov (United States)

    Lieberman et al. showed in a 1966 publication of Plant Physiology that methionine is a precursor of ethylene. It was the first paper that showed ethylene carbons are derived from carbons 3 and 4 of methionine. This paper catalyzed remarkable interest among plant biologists to elucidate the biosynth...

  16. A study on precursors leading to geomagnetic storms using artificial ...

    Indian Academy of Sciences (India)

    Space weather prediction involves advance forecasting of the magnitude and onset time of major geomagneticstorms on Earth. In this paper, we discuss the development of an artificial neural network-basedmodel to study the precursor leading to intense and moderate geomagnetic storms, following halo coronalmass ...

  17. Influence of hydrophobic characteristic of organo-modified precursor ...

    Indian Academy of Sciences (India)

    2016-08-26

    Aug 26, 2016 ... Influence of hydrophobic characteristic of organo-modified precursor on wettability of silica film ... 202, 6th district, P.O. Box 35-174, 060021 Bucharest, Romania; Faculty of Physics, University of Bucharest, 3Nano-SAE Research Centre, P.O. Box MG-38, 077125 Bucharest-Magurele, Romania; Faculty of ...

  18. Conditions for the differentiation of melanocyte-precursor cells from ...

    African Journals Online (AJOL)

    In addition, significant expression of microphthalmia-associated transcription factor-M and tyrosinase-related protein-1 genes was observed. These results suggest that a mixture of FK, SCF and EDN-3 induces the differentiation of melanocyte-precursor cells (MPCs) from CB-MSCs. Keywords: mesenchymal stem cells, ...

  19. NdRhSn: A ferromagnet with an antiferromagnetic precursor

    Czech Academy of Sciences Publication Activity Database

    Mihalik, M.; Prokleška, J.; Kamarád, Jiří; Prokeš, K.; Isnard, O.; McIntyre, G. J.; Dönni, A.; Yoshii, S.; Kitazawa, H.; Sechovský, V.; de Boer, F.R.

    2011-01-01

    Roč. 83, č. 10 (2011), "104403-1"-"104403-10" ISSN 1098-0121 R&D Projects: GA ČR GA202/09/1027 Institutional research plan: CEZ:AV0Z10100521 Keywords : NdRhSn * ferromagnet * antiferromagnetic precursor Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.691, year: 2011

  20. Measurement of excitation energy of neutron-rich precursor fragments

    Science.gov (United States)

    Mosby, Michelle Anthea

    Projectile fragmentation forms the basis for beam production at radioactive beam facilities such as the National Superconducting Cyclotron Laboratory (NSCL), yet uncertainties remain about the specifics of the production mechanism. For example, very little is known about the excitation energy of the precursors of the observed final fragments. In the present work, isotopes of sodium, neon, and fluorine produced in the fragmentation of a 32 Mg beam at 86 MeV/nucleon in a beryllium target, ranging in mass loss from DeltaA = 3--12, were observed and the coincident neutrons were detected using the Modular Neutron Array (MoNA). Neutron hit multiplicity in MoNA was compared to output from the statistical evaporation model PACE which was passed through a GEANT4 simulation to account for detector response with a X2v analysis. The neutron hit multiplicity distributions were used to determine the mass loss and excitation energy of the precursor fragments created in the fast step of the reaction. The mass loss and excitation energy were compared to abrasion/ablation models and an internuclear cascade model, ISABEL. For sodium and neon observed fragments, a single precursor mass was found, with a wide range of high excitation energies, up to 60 MeV. Observed fluorine isotopes were also found to have high excitation energies, ranging from 40--80 MeV, but with some variation in precursor mass.

  1. Carbon molecular sieve membranes prepared from porous fiber precursor

    NARCIS (Netherlands)

    Barsema, J.N.; van der Vegt, N.F.A.; Koops, G.H.; Wessling, Matthias

    2002-01-01

    Carbon molecular sieve (CMS) membranes are usually prepared from dense polymeric precursors that already show intrinsic gas separation properties. The rationale behind this approach is that the occurrence of any kind of initial porosity will deteriorate the final CMS performance. We will show that

  2. Development of precursors recognition methods in vector signals

    Science.gov (United States)

    Kapralov, V. G.; Elagin, V. V.; Kaveeva, E. G.; Stankevich, L. A.; Dremin, M. M.; Krylov, S. V.; Borovov, A. E.; Harfush, H. A.; Sedov, K. S.

    2017-10-01

    Precursor recognition methods in vector signals of plasma diagnostics are presented. Their requirements and possible options for their development are considered. In particular, the variants of using symbolic regression for building a plasma disruption prediction system are discussed. The initial data preparation using correlation analysis and symbolic regression is discussed. Special attention is paid to the possibility of using algorithms in real time.

  3. Polyazidopyrimidines: High Energy Compounds and Precursors to Carbon Nanotubes (Postprint)

    National Research Council Canada - National Science Library

    Ye, Chengfeng; Gao, Haixiang; Boatz, Jerry A; Drake, Gregory W; Twamley, Brendan; Shreeve, Jean'ne M

    2006-01-01

    ...). The compound 4,4',6,6'-tetra(azido)azo-1,3,5-triazine (2), has a heat of formation of 2171 (6164 kJ kg -1) (Fig. 1). Recently it was demonstrated that 1 and 2 were good precursors to nano carbon nitride materials...

  4. Synthesis and evaluation of some novel precursors of oxazolidinone ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 125; Issue 5. Synthesis and evaluation of some novel precursors of oxazolidinone analogues of chloroquinoline for their antimicrobial and cytotoxic potential. Kavita Devi Yumna Asmat Meenakshi Agrawal Swapnil Sharma Jaya Dwivedi. Volume 125 Issue 5 ...

  5. Corneal crystals: a precursor to cancer.

    Science.gov (United States)

    Chou, Janel L; Sink, Makesha L

    2011-04-01

    Corneal crystalline deposits are a sign of a limited number of conditions that can often be differentiated based on the appearance and pattern of the deposits. Although, there are limited treatment options available to reduce the appearance or effects of corneal crystals, it is important to identify the correct etiology of these deposits. There are several associated systemic conditions, some of which are life threatening, for which treatments are available. A 51-year-old black male presented to the clinic with the complaint of "glare at night due to crystals on [the] cornea." Slitlamp findings revealed diffuse subepithelial and anterior stromal crystals across both corneas. The patient had a medical history of renal insufficiency and arthralgia. Through systemic testing, the patient was found to have monoclonal gammopathy of undetermined significance (MGUS), and subsequent follow-up of this patient revealed a conversion of MGUS to multiple myeloma. Corneal crystals can appear diffusely through the cornea secondary to corneal dystrophies, gammopathies, cystinosis, or other rare systemic conditions. In this case report, these crystals are secondary to MGUS, which progressed to multiple myeloma. These crystals consist of immunoglobulin, primarily IgG, and excessive kappa light chains. It is important to obtain laboratory tests and make appropriate referrals to determine whether corneal crystal deposits are associated with a serious systemic disease or merely a corneal dystrophy.

  6. Geology and occurrence of radon precursors

    International Nuclear Information System (INIS)

    Schmalz, R.F.

    1990-01-01

    The discovery that radioactive radon gas may occur as a significant indoor contaminant in houses and in the workplace has had far-reaching consequences in public health, real estate marketing, the construction industry, health and liability insurance underwriting, and in legislation at the federal and state levels. Many factors are known to affect radon level inside a building - its location, construction, ventilation, and substructure; the climate of the region in which it is located and the life styles of it occupants, for example. Despite the importance of assessing the hazard radon contamination may represent, the economic cost and the time required to screen hundreds of millions of individual buildings make such an effort impracticable. The effectiveness of large-scale regional screening to evaluate radon potential depends on an understanding of the chemical and physical properties of the gas, and of the geological and geochemical factors which control the distribution of its radioactive progenitors, radium, uranium and thorium. It is the purpose of this paper to review and summarize our present knowledge of these large-scale controls on radon occurrence

  7. 1-Aminocyclopropane-1-carboxylic acid (ACC in plants: more than just the precursor of ethylene!

    Directory of Open Access Journals (Sweden)

    Bram eVan de Poel

    2014-11-01

    Full Text Available Ethylene is a simple two carbon atom molecule with profound effects on plants. There are quite a few review papers covering all aspects of ethylene biology in plants, including its biosynthesis, signaling and physiology. This is merely a logical consequence of the fascinating and pleiotropic nature of this gaseous plant hormone. Its biochemical precursor, 1-aminocyclopropane-1-carboxylic acid (ACC is also a fairly simple molecule, but perhaps its role in plant biology is seriously underestimated. This triangularly-shaped amino acid has many more features than just being the precursor of the lead-role player ethylene. For example, ACC can be conjugated to three different derivatives, but their biological role remains vague. ACC can also be metabolized by bacteria using ACC-deaminase, favoring plant growth and lowering stress susceptibility. ACC is also subjected to a sophisticated transport mechanism to ensure local and long-distance ethylene responses. Last but not least, there are now a few exciting studies where ACC has been reported to function as a signal itself, independently from ethylene. This review puts ACC in the spotlight, not to give it the lead-role, but to create a picture of the stunning co-production of the hormone and its precursor.

  8. 1-aminocyclopropane-1-carboxylic acid (ACC) in plants: more than just the precursor of ethylene!

    Science.gov (United States)

    Van de Poel, Bram; Van Der Straeten, Dominique

    2014-01-01

    Ethylene is a simple two carbon atom molecule with profound effects on plants. There are quite a few review papers covering all aspects of ethylene biology in plants, including its biosynthesis, signaling and physiology. This is merely a logical consequence of the fascinating and pleiotropic nature of this gaseous plant hormone. Its biochemical precursor, 1-aminocyclopropane-1-carboxylic acid (ACC) is also a fairly simple molecule, but perhaps its role in plant biology is seriously underestimated. This triangularly shaped amino acid has many more features than just being the precursor of the lead-role player ethylene. For example, ACC can be conjugated to three different derivatives, but their biological role remains vague. ACC can also be metabolized by bacteria using ACC-deaminase, favoring plant growth and lowering stress susceptibility. ACC is also subjected to a sophisticated transport mechanism to ensure local and long-distance ethylene responses. Last but not least, there are now a few exciting studies where ACC has been reported to function as a signal itself, independently from ethylene. This review puts ACC in the spotlight, not to give it the lead-role, but to create a picture of the stunning co-production of the hormone and its precursor. PMID:25426135

  9. Impacts of Lowered Urban Air Temperatures on Precursor Emission and Ozone Air Quality.

    Science.gov (United States)

    Taha, Haider; Konopacki, Steven; Akbari, Hashem

    1998-09-01

    Meteorological, photochemical, building-energy, and power plant simulations were performed to assess the possible precursor emission and ozone air quality impacts of decreased air temperatures that could result from implementing the "cool communities" concept in California's South Coast Air Basin (SoCAB). Two pathways are considered. In the direct pathway, a reduction in cooling energy use translates into reduced demand for generation capacity and, thus, reduced precursor emissions from electric utility power plants. In the indirect pathway, reduced air temperatures can slow the atmospheric production of ozone as well as precursor emission from anthropogenic and biogenic sources. The simulations suggest small impacts on emissions following implementation of cool communities in the SoCAB. In summer, for example, there can be reductions of up to 3% in NO x emissions from in-basin power plants. The photochemical simulations suggest that the air quality impacts of these direct emission reductions are small. However, the indirect atmospheric effects of cool communities can be significant. For example, ozone peak concentrations can decrease by up to 11% in summer and population-weighted exceedance exposure to ozone above the California and National Ambient Air Quality Standards can decrease by up to 11 and 17%, respectively. The modeling suggests that if these strategies are combined with others, such as mobile-source emission control, the improvements in ozone air quality can be substantial.

  10. Counter-propagating radiative shock experiments on the Orion laser and the formation of radiative precursors

    Science.gov (United States)

    Clayson, T.; Suzuki-Vidal, F.; Lebedev, S. V.; Swadling, G. F.; Stehlé, C.; Burdiak, G. C.; Foster, J. M.; Skidmore, J.; Graham, P.; Gumbrell, E.; Patankar, S.; Spindloe, C.; Chaulagain, U.; Kozlová, M.; Larour, J.; Singh, R. L.; Rodriguez, R.; Gil, J. M.; Espinosa, G.; Velarde, P.; Danson, C.

    2017-06-01

    We present results from new experiments to study the dynamics of radiative shocks, reverse shocks and radiative precursors. Laser ablation of a solid piston by the Orion high-power laser at AWE Aldermaston UK was used to drive radiative shocks into a gas cell initially pressurised between 0.1 and 1.0 bar with different noble gases. Shocks propagated at 80 ± 10 km/s and experienced strong radiative cooling resulting in post-shock compressions of ×25 ± 2. A combination of X-ray backlighting, optical self-emission streak imaging and interferometry (multi-frame and streak imaging) were used to simultaneously study both the shock front and the radiative precursor. These experiments present a new configuration to produce counter-propagating radiative shocks, allowing for the study of reverse shocks and providing a unique platform for numerical validation. In addition, the radiative shocks were able to expand freely into a large gas volume without being confined by the walls of the gas cell. This allows for 3-D effects of the shocks to be studied which, in principle, could lead to a more direct comparison to astrophysical phenomena. By maintaining a constant mass density between different gas fills the shocks evolved with similar hydrodynamics but the radiative precursor was found to extend significantly further in higher atomic number gases (∼4 times further in xenon than neon). Finally, 1-D and 2-D radiative-hydrodynamic simulations are presented showing good agreement with the experimental data.

  11. Wire-Array Precursor Plasma Interactions With On-Axis Foam Targets

    Science.gov (United States)

    Palmer, J. B. A.; Bland, S. N.

    2005-10-01

    The Dynamic Hohlraum (DH) Z-pinch on Z at Sandia National Laboratory (SNL) has been used to drive Inertial Confinement Fusion (ICF) and High Energy Density Physics (HEDP) relevant experiments. The power pulse from the DH cannot yet be reproduced using codes that can reproduce the performance of a Vacuum Hohlraum (VH) configuration on Z. Unlike the VH the DH has a low-density CH foam cylinder placed on the array axis. Production of precursor plasma, prior to the main implosion, is not included in the codes. This plasma is accelerated towards the array axis by the global J x B force and impacts onto the on-axis target. This bombardment alters the foam in various ways. Experiments have been performed on the 1 MA MAGPIE generator at Imperial College, London, to investigate the effect of this precursor bombardment. Diagnostics used were point-projection radiography with x-pinches, x-ray emission framing cameras, shadowgraphy and photoconduction diodes. Results show ablation of low-density plasma from the foam surface and compression of the foam by precursor pressure. Research sponsored by AWE, SNL, the SSAA program of NNSA under DOE Cooperative Agreement DE-FC03-02NA00057.

  12. Using a precursor in lamellar structure for the synthesis of uniform ZnS nanocrystals

    KAUST Repository

    Xu, Xinjiang

    2011-11-12

    Uniform ZnS nanocrystals of about 15 nm were prepared through a low temperature hydrothermal approach by treating Zn-PhPO nanosheets with Na 2S aqueous solution. Both the precursor and the final product were studied by the means of X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The photo-luminescent spectrum of the synthesized ZnS nanocrystals showed their good crystalline nature. Based on this study, the precursor structure-controlling effect was discussed, and in addition, the relevant factors possibly affecting the particle formation and the growth possessed were applied in the discussion to interpret the transformation mechanism. Further research showed that both the structure characters of the precursors and the mass transportation which occurred during the synthesis greatly affected the morphology and organization state of the final products. This research may provide some facts on the structure-controlling approaches along with a general method for the preparation of uniform sulfide nanocrystals. © Springer Science+Business Media B.V. 2011.

  13. Tuning the bimetallic amide-imide precursor system to make paramagnetic GaMnN nanopowders

    Energy Technology Data Exchange (ETDEWEB)

    Drygas, Mariusz [AGH University of Science and Technology, Faculty of Energy and Fuels, Al. Mickiewicza 30, 30-059 Krakow (Poland); Janik, Jerzy F., E-mail: janikj@agh.edu.pl [AGH University of Science and Technology, Faculty of Energy and Fuels, Al. Mickiewicza 30, 30-059 Krakow (Poland); Musial, Michal [AGH University of Science and Technology, Faculty of Energy and Fuels, Al. Mickiewicza 30, 30-059 Krakow (Poland); Gosk, Jacek [Warsaw University of Technology, Faculty of Physics, Koszykowa 75, 00-662 Warszawa (Poland); Twardowski, Andrzej, E-mail: andrzej.twardowski@fuw.edu.pl [University of Warsaw, Faculty of Physics, Pasteura 5, 02-093 Warszawa (Poland)

    2016-09-01

    A bimetallic molecular system made of gallium (III) tris(dimethyl)amide Ga(NMe{sub 2}){sub 3} and manganese (II) bis(trimethylsilyl)amide Mn[N(SiMe{sub 3}){sub 2}]{sub 2} (Me = CH{sub 3}, fixed initial Mn-content 10 at.%) was subjected to ammonolysis in refluxing/liquid ammonia. Upon isolation at room temperature, the amide-imide mixed metal precursor was pyrolyzed at elevated temperatures under an ammonia flow by two different routes. Route 1 consisted of a direct nitridation at high temperatures of 500, 700 or 900 °C. In route 2, a low temperature pyrolysis at 150 °C was applied prior to nitridation at the same final temperatures as in route 1. All nanopowders were characterized by XRD diffraction, FT-IR spectroscopy, and SEM/EDX microscopy and analysis. Thorough magnetization measurements in function of magnetic field and temperature were carried out with a SQUID magnetometer. In all samples, the paramagnetic phase of GaMnN was accompanied by an antiferromagnetic by-product linked to a Mn-containing species from decomposition and oxidation of Mn-precursor excess. The Mn-contents in the crystalline GaMnN, i.e., Mn-incorporated in GaN crystal lattice, were of the order of 2–3 at.% mostly independent on the nitridation route whereas the latter had a pronounced effect on amounts of the antiferromagnetic by-product. - Highlights: • New bimetallic precursor system for conversion to GaN/Mn nanopowders was designed. • Two conversion routes were applied with precursor nitridation at 500, 700 or 900 °C. • Prepared nanopowders were thoroughly characterized including magnetic measurements. • The major product was the gallium nitride Mn-doped phase GaMnN with 2–3 at.% of Mn.

  14. Precursors of Reading Skill from Infancy to First Grade in Finnish: Continuity and Change in a Highly Inflected Language

    Science.gov (United States)

    Silven, Maarit; Poskiparta, Elisa; Niemi, Pekka; Voeten, Marinus

    2007-01-01

    The course of language acquisition from infancy to public primary school was followed in a sample of 56 Finnish children to examine precursors to reading at first grade. Structural equation modeling of continuity suggested effects from growth in early vocabulary to mastery of inflectional forms at preschool age. The early language directly…

  15. Precursors of Reading Skill From Infancy to First Grade in Finnish: Continuity and Change in a Highly Inflected Language

    NARCIS (Netherlands)

    Silvén, M.; Poskiparta, E.H.; Niemi, P.; Voeten, M.J.M.

    2007-01-01

    The course of language acquisition from infancy to public primary school was followed in a sample of 56 Finnish children to examine precursors to reading at first grade. Structural equation modeling of continuity suggested effects from growth in early vocabulary to mastery of inflectional forms at

  16. Retrospective analysis for detecting seismic precursors in groundwater argon content

    Directory of Open Access Journals (Sweden)

    P. F. Biagi

    2004-01-01

    Full Text Available We examined the groundwater Argon content data sampled from 1988 to 2001 at two wells in Kamchatka (Russia and anomalous increases appeared clearly during June-July 1996. On 21 June, a shallow (1km earthquake with M=7.1 occurred at a distance less than 250km from the wells and so the previous increases could be related to this earthquake and, in particular, could be considered premonitory anomalies. In order to support this raw interpretation, we analysed the data collected in details. At first we smoothed out the high frequency fluctuations arising from the errors in a single measurement. Next we considered the known external effects on the water of a well that are the slow tectonic re-adjustment processes, the meteorology and the gravity tides and we separated these effects applying band-pass filters to the Argon content raw trends. Then we identified the largest fluctuations in these trends applying the 3 σ criterion and we found three anomalies in a case and two anomalies in other case. Comparing the time occurrence of the anomalies at the two wells we found out that a coincidence exists only in the case of the premonitory anomalies we are studying. The simultaneous appearance of well definite anomalies in the residual trends of the same parameter at two different sites supports their meaning and the possibility that they are related to some large scale effect, as the occurrence of a strong earthquake. But, other earthquakes similar to the June 1996 event took place during the Argon content measurements time and no anomaly appeared in this content. In the past, some of the authors of this paper studied the Helium content data collected in three natural springs of the Caucasus during seven years. A very similar result, that is the simultaneous appearance of clear premonitory anomalies only on the occasion of a strong (M=7.0 but shallow (2–4km earthquake, was obtained. The correspondence with the case of the Caucasus validates the

  17. Using superoxide dismutase/catalase mimetics to manipulate the redox environment of neural precursor cells

    International Nuclear Information System (INIS)

    Limoli, C. L.; Giedzinski, E.; Baure, J.; Doctrow, S. R.; Rola, R.; Fike, J. R.

    2006-01-01

    Past work has shown that neural precursor cells are predisposed to redox sensitive changes, and that oxidative stress plays a critical role in the acute and persistent changes that occur within the irradiated CNS. Irradiation leads to a marked rise in reactive oxygen species (ROS) that correlates with oxidative endpoints in vivo and reductions in neuro-genesis. To better understand the impact of oxidative stress on neural precursor cells, and to determine if radiation-induced oxidative damage and precursor cell loss after irradiation could be reduced, a series of antioxidant compounds (EUK-134, EUK-163, EUK-172, EUK-189) were tested, three of which possess both superoxide dismutase (SOD) and catalase activities and one (EUK-163) whose only significant activity is SOD. Our results show that these SOD/catalase mimetics apparently increase the oxidation of a ROS-sensitive fluorescent indicator dye, particularly after short (12 h) treatments, but that longer treatments (24 h) decrease oxidation attributable to radiation-induced ROS. Similarly, other studies found that cells incubated with CuZnSOD showed some increase in intracellular ROS levels. Subsequent data suggested that the dye-oxidising capabilities of the EUK compounds were linked to differences in their catalase activity and, most likely, their ability to catalyse per-oxidative pathways. In unirradiated mice, the EUK-134 analogue induced some decrease of proliferating precursor cells and immature neurons 48 h after radiation, an effect that may be attributable to cytotoxicity and/or inhibition of precursor proliferation. In irradiated mice, a single injection of EUK-134 was not found to be an effective radioprotector at acute times (48 h). The present results support continued development of our in vitro model as a tool for predicting certain in vivo responses, and suggest that in some biological systems the capability to scavenge superoxide but produce excess H 2 O 2 , as is known for CuZnSOD, may be

  18. Chemical precursor impact on the properties of Cu{sub 2}ZnSnS{sub 4} absorber layer

    Energy Technology Data Exchange (ETDEWEB)

    Vashistha, Indu B., E-mail: indu-139@yahoo.com; Sharma, S. K. [Department of Physics, Malaviya National Institute of Technology, Jaipur 302017 (India); Sharma, Mahesh C. [National Institute of Solar Energy, Gurgaon 122003 (India)

    2016-04-13

    In present work impact of different chemical precursor on the deposition of solar absorber layer Cu{sub 2}ZnSnS{sub 4} (CZTS) were studied by Chemical Bath Deposition (CBD) method without using expensive vacuum facilities and followed by annealing. As compared to the other deposition methods, CBD method is interesting one because it is simple, reproducible, non-hazardous, cost effective and well suited for producing large-area thin films at low temperatures, although effect of precursors and concentration plays a vital role in the deposition. So, the central theme of this work is optimizing and controlling of chemical reactions for different chemical precursors. Further Effect of different chemical precursors i.e. sulphate and chloride is analyzed by structural, morphological, optical and electrical properties. The X-ray diffraction (XRD) of annealed CZTS thin film revealed that films were polycrystalline in nature with kestarite tetragonal crystal structure. The Atomic Force micrographs (AFM) images indicated total coverage compact film and as well as growth of crystals. The band gap of annealed CZTS films was found in the range of optimal band gap by absorption spectroscopy.

  19. Platelet-derived growth factor BB enhances osteoclast formation and osteoclast precursor cell chemotaxis.

    Science.gov (United States)

    Li, Dian-Qi; Wan, Qi-Long; Pathak, Janak L; Li, Zu-Bing

    2017-07-01

    Enhanced osteoclast formation increases bone resorption, which triggers bone remodeling. Platelet-derived growth factor BB (PDGF-BB) enhances precursor cell homing, angiogenesis, and bone healing, and thereby could also treat osteoporosis. However, the effect of PDGF-BB on osteoclast formation is not fully understood. We investigated whether exogenous recombinant PDGF-BB directly affects osteoclast formation and osteoclast precursor cell chemotaxis. The murine monocyte-macrophage cell line RAW264.7 and bone-marrow-derived macrophages were cultured with recombinant mouse PDGF-BB with or without a platelet-derived growth factor receptor β inhibitor (AG-1295) or a Janus kinase 2 inhibitor (AG-490) to analyze the effect on osteoclastogenesis in vitro. PDGF-BB with or without AG-490 or AG-1295 was locally administrated in the mandibular fracture of 16-week-old Sprague Dawley rats (n = 18) for 1-2 weeks to analyze the effect on osteoclastogenesis in vivo. The effect of the treatments on osteoclast formation, osteoclast precursor cell migration, and expression of osteoclastogenic signaling molecules was analyzed. PDGF-BB enhanced osteoclast formation both in vitro and in vivo, but AG-490 and AG-1295 inhibited this effect. PDGF-BB enhanced phosphorylation of extracellular-signal-regulated kinase 1/2 (ERK1/2), Akt, and signal transducer and activator of transcription 3 (STAT3) in RAW264.7 cells. AG-490 inhibited PDGF-BB-induced STAT3 phosphorylation. PDGF-BB enhanced RAW264.7 cell migration and gene expression of osteoclastogenic signaling molecules (i.e., nuclear factor of activated T cells 1, dendrocyte-expressed seven transmembrane protein, and B-cell lymphoma 2), and treatment with AG-1295, AG-490, or S3I-201 (a STAT3 inhibitor) reduced this effect. PDGF-BB enhanced osteoclast formation, osteoclast precursor cell chemotaxis, and phosphorylation of STAT3, Akt, and ERK1/2. but AG-1295 and AG-490 reduced this effect. These findings reflect the complexity of

  20. Assessment of morphological changes and permeability of apical dentin surfaces induced by Nd:Yag laser irradiation through retrograde cavity surfaces.

    Science.gov (United States)

    Arisu, Hacer Deniz; Bala, Oya; Alimzhanova, Goulnara; Türköz, Emin

    2004-05-15

    The purpose of this in vitro study was to observe the morphological changes and apical dye penetration at apical dentin surfaces induced by Nd:YAG laser irradiation at different power settings with and without a laser initiator. Seventy five single rooted human maxillary anterior teeth were used. Following the establishment of the working lengths, the root canals were enlarged with step-back technique. The apex of each root was resected 3 mm perpendicular to its long axis. Standard Class I cavities of 2 mm depth and 2 mm width were prepared. The teeth were randomly divided into five groups with fifteen teeth in each. In Group 1, the retrograde cavity preparations were lased with Nd:YAG laser at 2 W and those in Group 2 preparations were lased with Nd:YAG laser at 3.2 W. In Group 3, the retrograde cavity surfaces were lased with Nd:YAG laser at 2 W following the application of India ink. Group 4 was lased with the same settings of Group 2 after an absorbent cotton point soaked with India ink was inserted into the cut dentinal surfaces and the inner walls of the apical preparations. Group 5 served as control. Five teeth from each group were examined using scanning electron microscopy (SEM). The amounts of smear layer, debris, and recrystalized dentin present were assessed and scored. Retrograde cavities of ten teeth from each group were filled with amalgam to examine apical dye penetration. The teeth were immersed in 2% basic fuscin and kept for 48 hours. Dye penetration was evaluated by stereomicroscope at a magnification of X10. The results showed the usage of India ink with Nd:YAG laser enhanced the amount of melting and recrystalization of dentin and the radiation and initiator increased the leakage.

  1. Surface Induced Dissociation Coupled with High Resolution Mass Spectrometry Unveils Heterogeneity of a 211 kDa Multicopper Oxidase Protein Complex

    Science.gov (United States)

    Zhou, Mowei; Yan, Jing; Romano, Christine A.; Tebo, Bradley M.; Wysocki, Vicki H.; Paša-Tolić, Ljiljana

    2018-01-01

    Manganese oxidation is an important biogeochemical process that is largely regulated by bacteria through enzymatic reactions. However, the detailed mechanism is poorly understood due to challenges in isolating and characterizing these unknown enzymes. A manganese oxidase, Mnx, from Bacillus sp. PL-12 has been successfully overexpressed in active form as a protein complex with a molecular mass of 211 kDa. We have recently used surface induced dissociation (SID) and ion mobility-mass spectrometry (IM-MS) to release and detect folded subcomplexes for determining subunit connectivity and quaternary structure. The data from the native mass spectrometry experiments led to a plausible structural model of this multicopper oxidase, which has been difficult to study by conventional structural biology methods. It was also revealed that each Mnx subunit binds a variable number of copper ions. Becasue of the heterogeneity of the protein and limited mass resolution, ambiguities in assigning some of the observed peaks remained as a barrier to fully understanding the role of metals and potential unknown ligands in Mnx. In this study, we performed SID in a modified Fourier transform-ion cyclotron resonance (FTICR) mass spectrometer. The high mass accuracy and resolution offered by FTICR unveiled unexpected artificial modifications on the protein that had been previously thought to be iron bound species based on lower resolution spectra. Additionally, isotopically resolved spectra of the released subcomplexes revealed the metal binding stoichiometry at different structural levels. This method holds great potential for in-depth characterization of metalloproteins and protein-ligand complexes. [Figure not available: see fulltext.

  2. Fission-Based Electric Propulsion for Interstellar Precursor Missions

    Energy Technology Data Exchange (ETDEWEB)

    HOUTS,MICHAEL G.; LENARD,ROGER X.; LIPINSKI,RONALD J.; PATTON,BRUCE; POSTON,DAVID; WRIGHT,STEVEN A.

    1999-11-03

    This paper reviews the technology options for a fission-based electric propulsion system for interstellar precursor missions. To achieve a total {Delta}V of more than 100 km/s in less than a decade of thrusting with an electric propulsion system of 10,000s Isp requires a specific mass for the power system of less than 35 kg/kWe. Three possible configurations are described: (1) a UZrH-fueled,NaK-cooled reactor with a steam Rankine conversion system,(2) a UN-fueled gas-cooled reactor with a recuperated Brayton conversion system, and (3) a UN-fueled heat pipe-cooled reactor with a recuperated Brayton conversion system. All three of these systems have the potential to meet the specific mass requirements for interstellar precursor missions in the near term. Advanced versions of a fission-based electric propulsion system might travel as much as several light years in 200 years.

  3. The miR-10 microRNA precursor family

    DEFF Research Database (Denmark)

    Tehler, Disa; Høyland-Kroghsbo, Nina Molin; Lund, Anders H

    2011-01-01

    The miR-10 microRNA precursor family encodes a group of short non-coding RNAs involved in gene regulation. The miR-10 family is highly conserved and has sparked the interest of many research groups because of the genomic localization in the vicinity of, coexpression with and regulation of the Hox...... gene developmental regulators. Here, we review the current knowledge of the evolution, physiological function and involvement in cancer of this family of microRNAs.......The miR-10 microRNA precursor family encodes a group of short non-coding RNAs involved in gene regulation. The miR-10 family is highly conserved and has sparked the interest of many research groups because of the genomic localization in the vicinity of, coexpression with and regulation of the Hox...

  4. Fission-Based Electric Propulsion for Interstellar Precursor Missions

    International Nuclear Information System (INIS)

    HOUTS, MICHAEL G.; LENARD, ROGER X.; LIPINSKI, RONALD J.; PATTON, BRUCE; POSTON, DAVID; WRIGHT, STEVEN A.

    1999-01-01

    This paper reviews the technology options for a fission-based electric propulsion system for interstellar precursor missions. To achieve a total ΔV of more than 100 km/s in less than a decade of thrusting with an electric propulsion system of 10,000s Isp requires a specific mass for the power system of less than 35 kg/kWe. Three possible configurations are described: (1) a UZrH-fueled,NaK-cooled reactor with a steam Rankine conversion system,(2) a UN-fueled gas-cooled reactor with a recuperated Brayton conversion system, and (3) a UN-fueled heat pipe-cooled reactor with a recuperated Brayton conversion system. All three of these systems have the potential to meet the specific mass requirements for interstellar precursor missions in the near term. Advanced versions of a fission-based electric propulsion system might travel as much as several light years in 200 years

  5. PREPARATION OF TANTALUM CARBIDE FROM AN ORGANOMETALLIC PRECURSOR

    Directory of Open Access Journals (Sweden)

    C. P. SOUZA

    1999-03-01

    Full Text Available In this work we have synthesized an organometallic oxalic precursor from tantalum oxide. This oxide was solubilized by heating with potassium hydrogen sulfate. In order to precipitate Ta2O5.nH2O, the fused mass obtained was dissolved in a sulfuric acid solution and neutralized with ammonia. The hydrated tantalum oxide precipitated was dissolved in an equimolar solution of oxalic acid/ammonium oxalate. The synthesis and the characterization of the tantalum oxalic precursor are described. Pyrolysis of the complex in a mixture of hydrogen and methane at atmospheric pressure was studied. The gas-solid reaction made it possible to obtain tantalum carbide, TaC, in the powder form at 1000oC. The natural sintering of TaC powder in an inert atmosphere at 1400°C during 10 hours, under inert atmosphere made it possible to densify the carbide to 96% of the theoretical value.

  6. Variability of doublecortin-associated dendrite maturation in adult hippocampal neurogenesis is independent of the regulation of precursor cell proliferation

    Directory of Open Access Journals (Sweden)

    Jessberger Sebastian

    2006-11-01

    Full Text Available Abstract Background In the course of adult hippocampal neurogenesis most regulation takes place during the phase of doublecortin (DCX expression, either as pro-proliferative effect on precursor cells or as survival-promoting effect on postmitotic cells. We here obtained quantitative data about the proliferative population and the dynamics of postmitotic dendrite development during the period of DCX expression. The question was, whether any indication could be obtained that the initiation of dendrite development is timely bound to the exit from the cell cycle. Alternatively, the temporal course of morphological maturation might be subject to additional regulatory events. Results We found that (1 20% of the DCX population were precursor cells in cell cycle, whereas more than 70% were postmitotic, (2 the time span until newborn cells had reached the most mature stage associated with DCX expression varied between 3 days and several weeks, (3 positive or negative regulation of precursor cell proliferation did not alter the pattern and dynamics of dendrite development. Dendrite maturation was largely independent of close contacts to astrocytes. Conclusion These data imply that dendrite maturation of immature neurons is initiated at varying times after cell cycle exit, is variable in duration, and is controlled independently of the regulation of precursor cell proliferation. We conclude that in addition to the major regulatory events in cell proliferation and selective survival, additional micro-regulatory events influence the course of adult hippocampal neurogenesis.

  7. Fabrication of a Cu(InGaSe2 Thin Film Photovoltaic Absorber by Rapid Thermal Annealing of CuGa/In Precursors Coated with a Se Layer

    Directory of Open Access Journals (Sweden)

    Chun-Yao Hsu

    2013-01-01

    Full Text Available Cu(InGaSe2 (CIGS thin film absorbers are prepared using sputtering and selenization processes. The CuGa/In precursors are selenized during rapid thermal annealing (RTA, by the deposition of a Se layer on them. This work investigates the effect of the Cu content in precursors on the structural and electrical properties of the absorber. Using X-ray diffraction, field emission scanning electron microscopy, Raman spectroscopy, and Hall effect measurement, it is found that the CIGS thin films produced exhibit facetted grains and a single chalcopyrite phase with a preferred orientation along the (1 1 2 plane. A Cu-poor precursor with a Cu/( ratio of 0.75 demonstrates a higher resistance, due to an increase in the grain boundary scattering and a reduced carrier lifetime. A Cu-rich precursor with a Cu/( ratio of 1.15 exhibits an inappropriate second phase ( in the absorber. However, the precursor with a Cu/( ratio of 0.95 exhibits larger grains and lower resistance, which is suitable for its application to solar cells. The deposition of this precursor on Mo-coated soda lime glass substrate and further RTA causes the formation of a MoSe2 layer at the interface of the Mo and CIGS.

  8. New Ir Bis-Carbonyl Precursor for Water Oxidation Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Daria L. [Department of Chemistry, Yale University, 225; Beltrán-Suito, Rodrigo [Department of Chemistry, Yale University, 225; Thomsen, Julianne M. [Department of Chemistry, Yale University, 225; Hashmi, Sara M. [Department of Chemical and Environmental; Materna, Kelly L. [Department of Chemistry, Yale University, 225; Sheehan, Stafford W. [Catalytic Innovations LLC, 70 Crandall; Mercado, Brandon Q. [Department of Chemistry, Yale University, 225; Brudvig, Gary W. [Department of Chemistry, Yale University, 225; Crabtree, Robert H. [Department of Chemistry, Yale University, 225

    2016-02-05

    This paper introduces IrI(CO)2(pyalc) (pyalc = (2-pyridyl)-2-propanoate) as an atom-efficient precursor for Ir-based homogeneous oxidation catalysis. This compound was chosen to simplify analysis of the water oxidation catalyst species formed by the previously reported Cp*IrIII(pyalc)OH water oxidation precatalyst. Here, we present a comparative study on the chemical and catalytic properties of these two precursors. Previous studies show that oxidative activation of Cp*Ir-based precursors with NaIO4 results in formation of a blue IrIV species. This activation is concomitant with the loss of the placeholder Cp* ligand which oxidatively degrades to form acetic acid, iodate, and other obligatory byproducts. The activation process requires substantial amounts of primary oxidant, and the degradation products complicate analysis of the resulting IrIV species. The species formed from oxidation of the Ir(CO)2(pyalc) precursor, on the other hand, lacks these degradation products (the CO ligands are easily lost upon oxidation) which allows for more detailed examination of the resulting Ir(pyalc) active species both catalytically and spectroscopically, although complete structural analysis is still elusive. Once Ir(CO)2(pyalc) is activated, the system requires acetic acid or acetate to prevent the formation of nanoparticles. Investigation of the activated bis-carbonyl complex also suggests several Ir(pyalc) isomers may exist in solution. By 1H NMR, activated Ir(CO)2(pyalc) has fewer isomers than activated Cp*Ir complexes, allowing for advanced characterization. Future research in this direction is expected to contribute to a better structural understanding of the active species. A diol crystallization agent was needed for the structure determination of 3.

  9. COS in the stratosphere. [sulfuric acid aerosol precursor

    Science.gov (United States)

    Inn, E. C. Y.; Vedder, J. F.; Tyson, B. J.; Ohara, D.

    1979-01-01

    Carbonyl sulfide (COS) has been detected in the stratosphere, and mixing ratio measurements are reported for altitudes of 15.2 to 31.2 km. A large volume, cryogenic sampling system mounted on board a U-2 aircraft has been used for lower stratosphere measurements and a balloon platform for measurement at 31.2 km. These observations and measurements strongly support the concept that stratospheric COS is an important precursor in the formation of sulfuric acid aerosols.

  10. Spectroscopy Study of Synthetic Forsterite Obtained from Zeolite Precursors

    OpenAIRE

    Kosanović, Cleo; Stubičar, Nada; Tomašić, N.; Stubičar, M.; Subotić, Boris; Gajović, Andreja; Sekovanić, L.

    2008-01-01

    Important ceramics materials are prepared from aluminosilicate based precursors using novel methods, offering at the same time a better control over many important properties. Forsterite, due to its good refractoriness with melting point at 2163 K, excellent electrical insulation properties even at high temperatures, low dielectric permittivity, thermal expansion and chemical stability, is a material of interest to engineers and designers especially as an active medium for tuneable laser and ...

  11. Hemopoietic cell precursor responses to erythropoietin in plasma clot cultures

    Energy Technology Data Exchange (ETDEWEB)

    Kennedy, W.L.

    1979-01-01

    The time dependence of the response of mouse bone marrow cells to erythropoietin (Ep) in vitro was studied. Experiments include studies on the Ep response of marrow cells from normal, plethoric, or bled mice. Results with normal marrow reveal: (1) Not all erythroid precursors (CFU-E) are alike in their response to Ep. A significant number of the precursors develop to a mature erythroid colony after very short Ep exposures, but they account for only approx. 13% of the total colonies generated when Ep is active for 48 hrs. If Ep is active more than 6 hrs, a second population of erythroid colonies emerges at a nearly constant rate until the end of the culture. Full erythroid colony production requires prolonged exposure to erythropoietin. (2) The longer erythropoietin is actively present, the larger the number of erythroid colonies that reach 17 cells or more. Two distinct populations of immediate erythroid precursors are also present in marrow from plethoric mice. In these mice, total colony numbers are equal to or below those obtained from normal mice. However, the population of fast-responding CFU-E is consistently decreased to 10 to 20% of that found in normal marrow. The remaining colonies are formed from plethoric marrow at a rate equal to normal marrow. With increasing Ep exposures, the number of large colonies produced increases. From the marrow of bled mice, total erythroid colony production is equal to or above that of normal marrow. Two populations of colony-forming cells are again evident, with the fast-responding CFU-E being below normal levels. The lack of colonies from this group was compensated in bled mice by rapid colony production in the second population. A real increase in numbers of precursors present in this pool increased the rate of colony production in culture to twice that of normal marrow. The number of large colonies obtained from bled mice was again increased as the Ep exposure was lengthened. (ERB)

  12. MHD precursor to disruption in Iran tokamak 1

    International Nuclear Information System (INIS)

    Alireza, Hojabri; Fatemeh, Hajakbari; Alireza, Hojabri; Mahmmod, Ghoranneviss; Fatemeh, Hajakbari

    2004-01-01

    The purpose of this paper is to investigate the major disruptions occurring in low-q(a) discharges in Iran Tokamak 1, and to compare the theoretical and experimental results for the rate of island growth. The study of precursor phase of disruption can be predicted and avoided using suitable control systems. In this paper are described the stability analysis and the observed growth rates indicating that the rotating modes are tearing modes. (authors)

  13. IL-9-Producing Mast Cell Precursors and Food Allergy

    Science.gov (United States)

    2016-10-01

    signaling enhances or attenuates allergic responses to food allergens. Methods: Mice of an IL-25 transgenic mouse line (iIL-25Tg mice), which...developing experimental food allergy, we generated IL-25 transgenic mouse lines (iIL-25Tg mice) that constitutively overexpress murine IL-25 driven by the...AD______________ AWARD NUMBER: W81XWH-15-1-0517 TITLE: IL-9-Producing Mast Cell Precursors and Food Allergy PRINCIPAL INVESTIGATOR: Dr. Yui

  14. Thin films by metal-organic precursor plasma spray

    International Nuclear Information System (INIS)

    Schulz, Douglas L.; Sailer, Robert A.; Payne, Scott; Leach, James; Molz, Ronald J.

    2009-01-01

    While most plasma spray routes to coatings utilize solids as the precursor feedstock, metal-organic precursor plasma spray (MOPPS) is an area that the authors have investigated recently as a novel route to thin film materials. Very thin films are possible via MOPPS and the technology offers the possibility of forming graded structures by metering the liquid feed. The current work employs metal-organic compounds that are liquids at standard temperature-pressure conditions. In addition, these complexes contain chemical functionality that allows straightforward thermolytic transformation to targeted phases of interest. Toward that end, aluminum 3,5-heptanedionate (Al(hd) 3 ), triethylsilane (HSi(C 2 H 5 ) 3 or HSiEt 3 ), and titanium tetrakisdiethylamide (Ti(N(C 2 H 5 ) 2 ) 4 or Ti(NEt 2 ) 4 ) were employed as precursors to aluminum oxide, silicon carbide, and titanium nitride, respectively. In all instances, the liquids contain metal-heteroatom bonds envisioned to provide atomic concentrations of the appropriate reagents at the film growth surface, thus promoting phase formation (e.g., Si-C bond in triethylsilane, Ti-N bond in titanium amide, etc.). Films were deposited using a Sulzer Metco TriplexPro-200 plasma spray system under various experimental conditions using design of experiment principles. Film compositions were analyzed by glazing incidence x-ray diffraction and elemental determination by x-ray spectroscopy. MOPPS films from HSiEt 3 showed the formation of SiC phase but Al(hd) 3 -derived films were amorphous. The Ti(NEt 2 ) 4 precursor gave MOPPS films that appear to consist of nanosized splats of TiOCN with spheres of TiO 2 anatase. While all films in this study suffered from poor adhesion, it is anticipated that the use of heated substrates will aid in the formation of dense, adherent films.

  15. What is the role of amyloid precursor protein dimerization?

    OpenAIRE

    Khalifa, Naouel Ben; Van Hees, Joanne; Tasiaux, Bernadette; Huysseune, Sandra; Smith, Steven O.; Constantinescu, Stefan N.; Octave, Jean-Noël; Kienlen-Campard, Pascal

    2010-01-01

    Extensive research efforts have been conducted over the past decades to understand the processing of the Amyloid Precursor Protein (APP). APP cleavage leads to the production of the beta-amyloid peptide (Abeta), which is the major constituent of the amyloid core of senile plaques found in the brains of patients with Alzheimer's disease (AD). Abeta is produced by the sequential cleavage of APP by beta- and gamma-secretases. Cleavage of APP by gamma-secretase also generates the APP Intracellula...

  16. The neuroleptic chlorpromazine inhibits the cationic and stimulates the anionic phospholipid precursor synthesis in human lymphocytes.

    Science.gov (United States)

    Staub, M; Stenger, A; Sumeg, R; Spasokoukotskaja, T; Fairbanks, L D; Simmonds, H A; Keszler, G

    2006-01-01

    The widely used neuroleptic drug chlorpromazine (CPZ) influences membrane functions at the levels of ionic channels and receptors as shown. Here we show the effect of short term treatments by CPZ (30 microM), on the nucleotide-containing phospholipid precursors in human lymphocyte primary cultures. During 60 minutes incubation of the cells, the CDP-ethanolamine (CDP-EA) content was only slightly reduced (87 to 76 pmol/10(6) cells), the amount of CDP-choline (CDP-Ch) was inhibited totally (from 25 to 0 pmol) upon the treatment with 30 microM CPZ under the same conditions. It has been shown earlier, that dCTP can be used as well as CTP for biosynthesis of phospholipids. Thus, the separation of the corresponding ribo- and deoxyribo-liponucleotides was developed. CPZ almost completely inhibited the synthesis of both dCDP-EA and dCDP-Ch under the same conditions The synthesis of the activated liponucleotide precursors, can be measured by incorporation of extracellular 14C-dCyt into both dCDP-EA and dCDP-Ch, as shown earlier. While the cationic deoxyribo-liponucleotide content (dCDP-Ch, dCDP-EA) was decreased, the labelling of the anionic phospholipid precursor dCDP-diacylglycerol (dCDP-DAG) was enhanced several times, it could be labelled only in the presence of CPZ from 14C-dCyd. Thus, a principal disturbance of the membrane phospholipid synthesis is presented (i.e., inhibition of the cationic and enhancement of the anionic dCDP-DAG synthesis). This profound influence on the membrane phospholipids by chlorpromazine, might be the primary effect that contributes to the wide spectrum of CPZ effects on neuronal cells.

  17. Valproic acid stimulates proliferation of glial precursors during cortical gliogenesis in developing rat.

    Science.gov (United States)

    Lee, Hee Jae; Dreyfus, Cheryl; DiCicco-Bloom, Emanuel

    2016-07-01

    Valproic acid (VPA) is a neurotherapeutic drug prescribed for seizures, bipolar disorder, and migraine, including women of reproductive age. VPA is a well-known teratogen that produces congenital malformations in many organs including the nervous system, as well as later neurodevelopmental disorders, including mental retardation and autism. In developing brain, few studies have examined VPA effects on glial cells, particularly astrocytes. To investigate effects on primary glial precursors, we developed new cell culture and in vivo models using frontal cerebral cortex of postnatal day (P2) rat. In vitro, VPA exposure elicited dose-dependent, biphasic effects on DNA synthesis and proliferation. In vivo VPA (300 mg/kg) exposure from P2 to P4 increased both DNA synthesis and cell proliferation, affecting primarily astrocyte precursors, as >75% of mitotic cells expressed brain lipid-binding protein. Significantly, the consequence of early VPA exposure was increased astrocytes, as both S100-β+ cells and glial fibrillary acidic protein were increased in adolescent brain. Molecularly, VPA served as an HDAC inhibitor in vitro and in vivo as enhanced proliferation was accompanied by increased histone acetylation, whereas it elicited changes in culture in cell-cycle regulators, including cyclin D1 and E, and cyclin-dependent kinase (CDK) inhibitors, p21 and p27. Collectively, these data suggest clinically relevant VPA exposures stimulate glial precursor proliferation, though at higher doses can elicit inhibition through differential regulation of CDK inhibitors. Because changes in glial cell functions are proposed as mechanisms contributing to neuropsychiatric disorders, these observations suggest that VPA teratogenic actions may be mediated through changes in astrocyte generation during development. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 780-798, 2016. © 2015 Wiley Periodicals, Inc.

  18. Development of techniques for tagging precursor and essential chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Swansiger, W.A.; Shepodd, T.J. [Sandia National Labs., Livermore, CA (United States); Phillips, M.L.F. [Sandia National Labs., Albuquerque, NM (United States)

    1994-01-01

    The ability to identify the manufacturers and distributors of chemicals seized in raids of illicit drug labs would be of great value in controlling the diversion of these chemicals. We developed a tagging scheme based on the addition of sub-ppM concentrations of various combinations of rare-earth elements to the target chemicals and evaluated a number of techniques for detecting the tags. We developed soluble tags for tagging liquids and selected Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) as the preferred detection technique. We developed insoluble tags for tagging solids and developed methods to analyze them and mix them into solid precursors. We have successfully demonstrated the tagging of several solvents and two of the precursor chemicals used in one of the most popular clandestine methamphetamine syntheses (ephedrine reacting with hydriodic acid/red phosphorus). The tagging scheme is capable of yielding tens of thousands of signatures (using holmium as an internal standard and up to 9 rare-earths at up to 3 concentrations yields 3{sup 9} {minus} 1 = 19,682 signatures) and is applicable to most of the chemicals on the precursor and essential chemicals list. In the concentrations employed, the tags are safe enough to be added to pharmaceuticals and cheap enough to tag tanker loads of chemicals.

  19. Assigning probability gain for precursors of four large Chinese earthquakes

    Energy Technology Data Exchange (ETDEWEB)

    Cao, T.; Aki, K.

    1983-03-10

    We extend the concept of probability gain associated with a precursor (Aki, 1981) to a set of precursors which may be mutually dependent. Making use of a new formula, we derive a criterion for selecting precursors from a given data set in order to calculate the probability gain. The probabilities per unit time immediately before four large Chinese earthquakes are calculated. They are approximately 0.09, 0.09, 0.07 and 0.08 per day for 1975 Haicheng (M = 7.3), 1976 Tangshan (M = 7.8), 1976 Longling (M = 7.6), and Songpan (M = 7.2) earthquakes, respectively. These results are encouraging because they suggest that the investigated precursory phenomena may have included the complete information for earthquake prediction, at least for the above earthquakes. With this method, the step-by-step approach to prediction used in China may be quantified in terms of the probability of earthquake occurrence. The ln P versus t curve (where P is the probability of earthquake occurrence at time t) shows that ln P does not increase with t linearly but more rapidly as the time of earthquake approaches.

  20. LWIR hyperspectral imaging application and detection of chemical precursors

    Science.gov (United States)

    Lavoie, Hugo; Thériault, Jean-Marc; Bouffard, François; Puckrin, Eldon; Dubé, Denis

    2012-10-01

    Detection and identification of Toxic industrial chemicals (TICs) represent a major challenge to protect and sustain first responder and public security. In this context, passive Hyperspectral Imaging (HSI) is a promising technology for the standoff detection and identification of chemical vapors emanating from a distant location. To investigate this method, the Department of National Defense and Public Safety Canada have mandated Defense Research and Development Canada (DRDC) - Valcartier to develop and test Very Long Wave Infrared (VLWIR) HSI sensors for standoff detection. The initial effort was focused to address the standoff detection and identification of toxic industrial chemicals (TICs), surrogates and precursors. Sensors such as the Improved Compact ATmospheric Sounding Interferometer (iCATSI) and the Multi-option Differential Detection and Imaging Fourier Spectrometer (MoDDIFS) were developed for this application. This paper presents the sensor developments and preliminary results of standoff detection and identification of TICs and precursors. The iCATSI and MoDDIFS sensors are based on the optical differential Fourier-transform infrared (FTIR) radiometric technology and are able to detect, spectrally resolve and identify small leak at ranges in excess of 1 km. Results from a series of trials in asymmetric threat type scenarios are reported. These results serve to establish the potential of passive standoff HSI detection of TICs, precursors and surrogates.

  1. Correlation between intracellular accumulation of peptidoglycan precursors and streptomycin formation

    International Nuclear Information System (INIS)

    Nimi, Osamu; Kawashima, Hiroki; Sugiyama, Masanori; Nomi, Ryosaku

    1984-01-01

    When the mycelium of Streptomyces HUT 6037 was suspended in 0.5% NaCl solution containing 14 C-glucosamine, peptidoglycan precursors accumulated in the cells. While UDP-N-acetylglucosamine accumulated in the largest amount among the precursors, extracellularly added and intracellularly accumulated UDP-N-acetylglucosamine were not used to synthesize streptomycin and were probably used for peptidoglycan formation. On the other hand, correlation was recognized between accumulation of glucosamine-6-phosphate (GlcN-6P) and streptomycin formation. Addition of an inhibitor of peptidoglycan synthesis such as enduracidin, vancomycin or cycloserine to a mycelium-suspended culture changed the ratio of accumulated peptidoglycan precursors. When streptomycin formation was stimulated by addition of enduracidin or vancomycin, intracellular GlcN-6P remarkably increased and then decreased rapidly. On the contrary, when cycloserine was added to the culture, no increase of GlcN-6P was observed and streptomycin formation was not stimulated. These results suggest that an increase in the intracellular concentration of GlcN-6P is required for activation or induction of the system for utilizing GlcN-6P for streptomycin formation. (author)

  2. Production of jet fuel precursor monoterpenoids from engineered Escherichia coli.

    Science.gov (United States)

    Mendez-Perez, Daniel; Alonso-Gutierrez, Jorge; Hu, Qijun; Molinas, Margaux; Baidoo, Edward E K; Wang, George; Chan, Leanne J G; Adams, Paul D; Petzold, Christopher J; Keasling, Jay D; Lee, Taek S

    2017-08-01

    Monoterpenes (C 10 isoprenoids) are the main components of essential oils and are possible precursors for many commodity chemicals and high energy density fuels. Monoterpenes are synthesized from geranyl diphosphate (GPP), which is also the precursor for the biosynthesis of farnesyl diphosphate (FPP). FPP biosynthesis diverts the carbon flux from monoterpene production to C 15 products and quinone biosynthesis. In this study, we tested a chromosomal mutation of Escherichia coli's native FPP synthase (IspA) to improve GPP availability for the production of monoterpenes using a heterologous mevalonate pathway. Monoterpene production at high levels required not only optimization of GPP production but also a basal level of FPP to maintain growth. The optimized strains produced two jet fuel precursor monoterpenoids 1,8-cineole and linalool at the titer of 653 mg/L and 505 mg/L, respectively, in batch cultures with 1% glucose. The engineered strains developed in this work provide useful resources for the production of high-value monoterpenes. Biotechnol. Bioeng. 2017;114: 1703-1712. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  3. Reduction of precursor decay anomaly in single crystal lithium fluoride

    Science.gov (United States)

    Sano, Yukio

    2000-08-01

    The purpose of this study is to reveal that the precursor decay anomaly in single crystal lithium fluoride is reduced by Sano's decay curve [Y. Sano, J. Appl. Phys. 85, 7616 (1999)], which is much smaller in slope than Asay's decay curve [J. R. Asay, G. R. Fowles, G. E. Duvall, M. H. Miles, and R. F. Tinder, J. Appl. Phys. 43, 2132 (1972)]. To this end, strain, particle, velocity, and stress in a precursor and near the leading edge of the follower changing with time along Sano's decay curve are first analyzed quantitatively. The analysis verified the existence of degenerate contraction waves I and II and a subrarefaction wave R', and the decay process [Y. Sano, J. Appl. Phys. 77, 3746 (1995)] caused in sequence by evolving followers C, I, II, R', Rb. Next, inequalities relating decay rates qualitatively to plastic strain rates at the leading edge of the follower, which are derived using the properties of the followers, are incorporated into the analysis. Calculation results showed that the plastic strain rates were reduced by low decay rates. This indicates that the precursor decay anomaly might be greatly reduced by Sano's decay curve.

  4. Spectroscopy Study of Synthetic Forsterite Obtained from Zeolite Precursors

    Directory of Open Access Journals (Sweden)

    Subotić, B.

    2008-02-01

    Full Text Available Important ceramics materials are prepared from aluminosilicate based precursors using novel methods, offering at the same time a better control over many important properties. Forsterite, due to its good refractoriness with melting point at 2163 K, excellent electrical insulation properties even at high temperatures, low dielectric permittivity, thermal expansion and chemical stability, is a material of interest to engineers and designers especially as an active medium for tuneable laser and is also a material of interest to SOFC (Solid oxide fuel cells manufacturers. The aim of this study is to investigate the synthesis of crystalline forsterite using different zeolite precursors previously activated by ball milling. Synthetic forsterite was synthesized from different zeolite precursors and MgO combining highenergy ball milling and thermal treatment of the mixture under determined conditions of time and temperature for each operation. In this research are studied the solid-state phase transformations taking place at temperatures below 1273 K. The obtained products were characterized using different spectroscopy techniques in comparison with surface analysis method and X-ray diffraction.

  5. Precursor Analysis for Flight- and Ground-Based Anomaly Risk Significance Determination

    Science.gov (United States)

    Groen, Frank

    2010-01-01

    This slide presentation reviews the precursor analysis for flight and ground based anomaly risk significance. It includes information on accident precursor analysis, real models vs. models, and probabilistic analysis.

  6. A possible island of beta-delayed neutron precursors in heavy nucleus region

    International Nuclear Information System (INIS)

    Zhang Li

    1991-01-01

    The possible Beta-Delayed neutron precursors in the elements Tl, Hg, and Au were predicted following a systematic research on the known Beta-Delayed neutron precursors. The masses of the unknown nuclei and neutron emission probabilities were calculated

  7. ETOH inhibits embryonic neural stem/precursor cell proliferation via PLD signaling

    International Nuclear Information System (INIS)

    Fujita, Yuko; Hiroyama, Masami; Sanbe, Atsushi; Yamauchi, Junji; Murase, Shoko; Tanoue, Akito

    2008-01-01

    While a mother's excessive alcohol consumption during pregnancy is known to have adverse effects on fetal neural development, little is known about the underlying mechanism of these effects. In order to investigate these mechanisms, we investigated the toxic effect of ethanol (ETOH) on neural stem/precursor cell (NSC) proliferation. In cultures of NSCs, phospholipase D (PLD) is activated following stimulation with epidermal growth factor (EGF) and fibroblast growth factor 2 (FGF2). Exposure of NSCs to ETOH suppresses cell proliferation, while it has no effect on cell death. Phosphatidic acid (PA), which is a signaling messenger produced by PLD, reverses ETOH inhibition of NSC proliferation. Blocking the PLD signal by 1-butanol suppresses the proliferation. ETOH-induced suppression of NSC proliferation and the protective effect of PA for ETOH-induced suppression are mediated through extracellular signal-regulated kinase signaling. These results indicate that exposure to ETOH impairs NSC proliferation by altering the PLD signaling pathway

  8. Pig epidermal growth factor precursor contains segments that are highly conserved among species

    DEFF Research Database (Denmark)

    Jørgensen, P E; Jensen, L.G.; Sørensen, B S

    1998-01-01

    The 53-aa polypeptide epidermal growth factor (EGF) is synthesized as a 1200-aa precursor. The non-EGF part of the precursor is very long compared with EGF, and can therefore be expected to have a biological role of its own. We have sequenced cDNA of the pig EGF precursor and compared a 668-aa...

  9. Functional Analysis of Precursors for Serious Problem Behavior and Related Intervention

    Science.gov (United States)

    Langdon, Nancy A.; Carr, Edward G.; Owen-DeSchryver, Jamie S.

    2008-01-01

    Precursor behaviors are innocuous behaviors that reliably precede the occurrence of problem behavior. Intervention efforts applied to precursors might prevent the occurrence of severe problem behavior. We examined the relationship between precursor behavior and problem behavior in three individuals with developmental disabilities. First, a…

  10. Sonic Hedgehog Controls the Phenotypic Fate and Therapeutic Efficacy of Grafted Neural Precursor Cells in a Model of Nigrostriatal Neurodegeneration

    OpenAIRE

    Madhavan, Lalitha; Daley, Brian F.; Davidson, Beverly L.; Boudreau, Ryan L.; Lipton, Jack W.; Cole-Strauss, Allyson; Steece-Collier, Kathy; Collier, Timothy J.

    2015-01-01

    The expression of soluble growth and survival promoting factors by neural precursor cells (NPCs) is suggested to be a prominent mechanism underlying the protective and regenerative effects of these cells after transplantation. Nevertheless, how and to what extent specific NPC-expressed factors contribute to therapeutic effects is not well understood. Using RNA silencing, the current study investigated the roles of two donor NPC molecules, namely glial cell-line derived neurotrophic factor (GD...

  11. Wetlands receiving water treated with coagulants improve water quality by removing dissolved organic carbon and disinfection byproduct precursors.

    Science.gov (United States)

    Hansen, Angela M; Kraus, Tamara E C; Bachand, Sandra M; Horwath, William R; Bachand, Philip A M

    2018-05-01

    Constructed wetlands are used worldwide to improve water quality while also providing critical wetland habitat. However, wetlands have the potential to negatively impact drinking water quality by exporting dissolved organic carbon (DOC) that upon disinfection can form disinfection byproducts (DBPs) like trihalomethanes (THMs) and haloacetic acids (HAAs). We used a replicated field-scale study located on organic rich soils in California's Sacramento-San Joaquin Delta to test whether constructed flow-through wetlands which receive water high in DOC that is treated with either iron- or aluminum-based coagulants can improve water quality with respect to DBP formation. Coagulation alone removed DOC (66-77%) and THM (67-70%) precursors, and was even more effective at removing HAA precursors (77-90%). Passage of water through the wetlands increased DOC concentrations (1.5-7.5mgL -1 ), particularly during the warmer summer months, thereby reversing some of the benefits from coagulant addition. Despite this addition, water exiting the wetlands treated with coagulants had lower DOC and DBP precursor concentrations relative to untreated source water. Benefits of the coagulation-wetland systems were greatest during the winter months (approx. 50-70% reduction in DOC and DBP precursor concentrations) when inflow water DOC concentrations were higher and wetland DOC production was lower. Optical properties suggest DOC in this system is predominantly comprised of high molecular weight, aromatic compounds, likely derived from degraded peat soils. Published by Elsevier B.V.

  12. Possibility to study ionospheric earthquakes precursors using CubeSats

    Science.gov (United States)

    Korepanov, Valery; Lappas, Vaios

    It is generally accepted that the earthquakes (EQ) are the most dangerous natural phenomena leading to the multiple losses in human lives and economics. The space observations must be included into the global chain of the EQ precursors monitoring at least as the initial warning to pay greater attention to the ground segment data. As the common opinion agrees, only in combination of multiple observation sites and set of monitored parameters the further progress at the way to raise EQ precursors detection probability may be obtained. There is necessary to answer two important questions before to plan any experiment to study ionospheric precursors of EQ. First one - whether the variations in the ionosphere definitely connected with the EQ preparation process do exist, and the second one - if they do, whether using these signals the precursors of EQ can be reliably identified and used for, if not prediction, then for the warning that the EQ in the given area approaches. The first successful mission dedicated to this problem solution was DEMETER (in orbit during more than 6 years from June 2004 until December 2010). The statistics of this study is impressive: altogether, about 9000 EQs with magnitude larger than M = 5.0 and depth lower than 40 km occurred all over the world during the analyzed period. In the result, the conclusion made there suggests that, obviously, there are real perturbations in the ionosphere connected with the seismic activity, but they are rather weak and at the present stage of data processing may be revealed only with the help of statistical analysis. To realize the study of ionospheric precursors, first it is imperative to clarify the mechanism of energy transfer along the chain “lithosphere-atmosphere-ionosphere”. Many hypotheses of such a mechanism exist, from which the mostly supported are fair weather currents (FWC) and atmospheric gravity waves (AGW), both of which have their pros and contras. The following minimal set of physical

  13. Synthesis of polymeric fluorinated sol–gel precursor for fabrication of superhydrophobic coating

    International Nuclear Information System (INIS)

    Li, Qianqian; Yan, Yuheng; Yu, Miao; Song, Botao; Shi, Suqing; Gong, Yongkuan

    2016-01-01

    Graphical abstract: - Highlights: • A polymeric fluorinated sol–gel precursor PFT is designed to fabricate superhydrophobic coatings. • The superhydrophobicity could be governed by the concentration of PFT. • Bio-mimicking self-cleaning property similar to lotus leaves could also be achieved. - Abstract: A fluorinated polymeric sol–gel precursor (PFT) is synthesized by copolymerization of 2,3,4,5,5,5-hexafluoro-2,4-bis(trifluorinated methyl)pentyl methacrylate (FMA) and 3-methacryloxypropyltrimethoxysilane (TSMA) to replace the expensive long chain fluorinated alkylsilanes. The fluorinated silica sol is prepared by introducing PFT as co-precursor of tetraethyl orthosilicate (TEOS) in the sol–gel process with ammonium hydroxide as catalyst, which is then used to fabricate superhydrophobic coating on glass substrate through a simple dip-coating method. The effects of PFT concentrations on the chemical structure of the formed fluorinated silica, the surface chemical composition, surface morphology, wetting and self-cleaning properties of the resultant fluorinated silica coatings were studied by using X-ray powder diffraction (XRD), Fourier transform infrared spectrometer (FTIR), X-ray photoelectron spectrophotometer (XPS), scanning electron microscopy (SEM) and water contact angle measurements (WCA). The results show that the fluorinated silica sols are successfully obtained. The size and size distribution of the fluorinated silica particles are found greatly dependent on the concentration of PFT, which play a crucial role in the surface morphology of the corresponding fluorinated silica coatings. The suitable PFT concentration added in the sol–gel stage, i.e. for F-sol-1 and F-sol-2, is helpful to achieve both the low surface energy and multi-scaled microstructures, leading to the formation of the superhydrophobic coatings with bio-mimicking self-cleaning property similar to lotus leaves.

  14. Next-Generation Probiotics Targeting Clostridium difficile through Precursor-Directed Antimicrobial Biosynthesis

    Science.gov (United States)

    Auchtung, Jennifer; Brown, Aaron; Boonma, Prapaporn; Oezguen, Numan; Ross, Caná L.; Luna, Ruth Ann; Runge, Jessica; Versalovic, James; Peniche, Alex; Dann, Sara M.; Britton, Robert A.; Haag, Anthony; Savidge, Tor C.

    2017-01-01

    ABSTRACT Integration of antibiotic and probiotic therapy has the potential to lessen the public health burden of antimicrobial-associated diseases. Clostridium difficile infection (CDI) represents an important example where the rational design of next-generation probiotics is being actively pursued to prevent disease recurrence. Because intrinsic resistance to clinically relevant antibiotics used to treat CDI (vancomycin, metronidazole, and fidaxomicin) is a desired trait in such probiotic species, we screened several bacteria and identified Lactobacillus reuteri to be a promising candidate for adjunct therapy. Human-derived L. reuteri bacteria convert glycerol to the broad-spectrum antimicrobial compound reuterin. When supplemented with glycerol, strains carrying the pocR gene locus were potent reuterin producers, with L. reuteri 17938 inhibiting C. difficile growth at a level on par with the level of growth inhibition by vancomycin. Targeted pocR mutations and complementation studies identified reuterin to be the precursor-induced antimicrobial agent. Pathophysiological relevance was demonstrated when the codelivery of L. reuteri with glycerol was effective against C. difficile colonization in complex human fecal microbial communities, whereas treatment with either glycerol or L. reuteri alone was ineffective. A global unbiased microbiome and metabolomics analysis independently confirmed that glycerol precursor delivery with L. reuteri elicited changes in the composition and function of the human microbial community that preferentially targets C. difficile outgrowth and toxicity, a finding consistent with glycerol fermentation and reuterin production. Antimicrobial resistance has thus been successfully exploited in the natural design of human microbiome evasion of C. difficile, and this method may provide a prototypic precursor-directed probiotic approach. Antibiotic resistance and substrate bioavailability may therefore represent critical new determinants of

  15. Local Deformation Precursors of Large Earthquakes Derived from GNSS Observation Data

    Science.gov (United States)

    Kaftan, Vladimir; Melnikov, Andrey

    2017-12-01

    Research on deformation precursors of earthquakes was of immediate interest from the middle to the end of the previous century. The repeated conventional geodetic measurements, such as precise levelling and linear-angular networks, were used for the study. Many examples of studies referenced to strong seismic events using conventional geodetic techniques are presented in [T. Rikitake, 1976]. One of the first case studies of geodetic earthquake precursors was done by Yu.A. Meshcheryakov [1968]. Rare repetitions, insufficient densities and locations of control geodetic networks made difficult predicting future places and times of earthquakes occurrences. Intensive development of Global Navigation Satellite Systems (GNSS) during the recent decades makes research more effective. The results of GNSS observations in areas of three large earthquakes (Napa M6.1, USA, 2014; El Mayor Cucapah M7.2, USA, 2010; and Parkfield M6.0, USA, 2004) are treated and presented in the paper. The characteristics of land surface deformation before, during, and after earthquakes have been obtained. The results prove the presence of anomalous deformations near their epicentres. The temporal character of dilatation and shear strain changes show existence of spatial heterogeneity of deformation of the Earth’s surface from months to years before the main shock close to it and at some distance from it. The revealed heterogeneities can be considered as deformation precursors of strong earthquakes. According to historical data and proper research values of critical deformations which are offered to be used for seismic danger scale creation based on continuous GNSS observations are received in a reference to the mentioned large earthquakes. It is shown that the approach has restrictions owing to uncertainty of the moment in the beginning of deformation accumulation and the place of expectation of another seismic event. Verification and clarification of the derived conclusions are proposed.

  16. Investigation of Droplet Atomization and Evaporation in Solution Precursor Plasma Spray Coating

    Directory of Open Access Journals (Sweden)

    Hongbing Xiong

    2017-11-01

    Full Text Available Solution precursor plasma spray (SPPS is a novel and promising technique in producing nanostructured coatings. This technique involves complex heat, mass and momentum transfer among the liquid feedstock, droplets, plasma jet and the coating material. Nevertheless, the droplet atomization and evaporation in the plasma jet is one of the most essential parts to obtain the desired coating architecture. In the present work, a three-dimensional two-way-coupled Eulerian-Lagrangian code is used to simulate the interactions between the solution precursor and plasma. In order to obtain a more realistic understanding regarding droplet atomization and vaporization, the flash-boiling effect is modeled by an improved vaporization model. This model could provide accurate details for the droplet pyrolysis and help to optimize the solution precursor plasma spray process. We show that the fragmentation of the liquid stock and its vaporization mainly dominate the spraying details and can be decisive to the coating quality. We further investigate their role in SPPS and separately probe their inner link with the flow field relating to the distinctive area when droplets are flying through the thermal flow field. Our studies reveal that ethanol droplets, compared to those of water, show a superior characteristics in SPPS, owing to the low boiling point and low surface tension, conducive to the evaporation and atomization of droplets. In addition, the mixture of the plasma gas with hydrogen breaks the droplets more thoroughly compared to the pure plasma. The numerical results were compared and found to agree well with previous experimental and simulation work.

  17. Next-Generation Probiotics Targeting Clostridium difficile through Precursor-Directed Antimicrobial Biosynthesis.

    Science.gov (United States)

    Spinler, Jennifer K; Auchtung, Jennifer; Brown, Aaron; Boonma, Prapaporn; Oezguen, Numan; Ross, Caná L; Luna, Ruth Ann; Runge, Jessica; Versalovic, James; Peniche, Alex; Dann, Sara M; Britton, Robert A; Haag, Anthony; Savidge, Tor C

    2017-10-01

    Integration of antibiotic and probiotic therapy has the potential to lessen the public health burden of antimicrobial-associated diseases. Clostridium difficile infection (CDI) represents an important example where the rational design of next-generation probiotics is being actively pursued to prevent disease recurrence. Because intrinsic resistance to clinically relevant antibiotics used to treat CDI (vancomycin, metronidazole, and fidaxomicin) is a desired trait in such probiotic species, we screened several bacteria and identified Lactobacillus reuteri to be a promising candidate for adjunct therapy. Human-derived L. reuteri bacteria convert glycerol to the broad-spectrum antimicrobial compound reuterin. When supplemented with glycerol, strains carrying the pocR gene locus were potent reuterin producers, with L. reuteri 17938 inhibiting C. difficile growth at a level on par with the level of growth inhibition by vancomycin. Targeted pocR mutations and complementation studies identified reuterin to be the precursor-induced antimicrobial agent. Pathophysiological relevance was demonstrated when the codelivery of L. reuteri with glycerol was effective against C. difficile colonization in complex human fecal microbial communities, whereas treatment with either glycerol or L. reuteri alone was ineffective. A global unbiased microbiome and metabolomics analysis independently confirmed that glycerol precursor delivery with L. reuteri elicited changes in the composition and function of the human microbial community that preferentially targets C. difficile outgrowth and toxicity, a finding consistent with glycerol fermentation and reuterin production. Antimicrobial resistance has thus been successfully exploited in the natural design of human microbiome evasion of C. difficile , and this method may provide a prototypic precursor-directed probiotic approach. Antibiotic resistance and substrate bioavailability may therefore represent critical new determinants of probiotic

  18. Understanding the influence of alendronate on the morphology and phase transformation of apatitic precursor nanocrystals.

    Science.gov (United States)

    Zhang, Guiling; Huang, Rong; Li, Zhicheng; Yang, Xianyan; Chen, Xiaoyi; Xia, Wei; Sun, Xiaoliang; Yang, Guojing; Gao, Changyou; Gou, Zhongru

    2012-08-01

    Bisphosphonates (BPs) are a class of synthetic pyrophosphate analogs that can prevent the loss of bone mass, given orally to treat postmenopuasal osteoporosis. It is not clear yet if the benefits of BPs include the possibility of affecting bone apatitic precursors transition for bone consolidation except for encouraging osteoclasts to undergo apoptosis. Furthermore, the complexity of the in vivo system makes it difficult to isolate and study such extracellular topographical cues that trigger bone turnover response. Herein, we proposed a wet-chemical approach employing alendronate sodium (AS) as a guide of hydroxyapatite (HA) precursor growth and conversion which was initiated from the nucleantion of octacalcium phosphate (OCP) in a cell membrane-mimicking surfactant micelle aqueous system. The nanocrystal clusters of dicalcium phosphate dihydrate (DCPD) and OCP nanocryatals were readily precipitated within a relatively narrow AS concentration range (2-8 μM). However, such low concentrations of AS seemed to stabilize the more acidic phases, and to delay the transformation into HA, to an extent which increased on increasing AS concentration. In contrast, at a slight higher concentrations (16-32 μM), AS promoted HA precipitation after ageing for 1h. It was found that the effect of AS on the phase selectivity of apatitic precursors was concentration-dependent within a prolonged ageing time stage (0.5-168 h). The AS-assisted reactions in vitro offer an expedient way to understand the underlying implementarity between bone and BPs for bone consolidation, and to improve our understanding of benefit of BP dosages on bone turnover and trauma healing. Copyright © 2012 Elsevier Inc. All rights reserved.

  19. Lithosphere-Atmosphere-Ionosphere Coupling (LAIC) Model - An Unified Concept for Earthquake Precursors Validation

    Science.gov (United States)

    Pulinets, S.; Ouzounov, D.

    2010-01-01

    The paper presents a conception of complex multidisciplinary approach to the problem of clarification the nature of short-term earthquake precursors observed in atmosphere, atmospheric electricity and in ionosphere and magnetosphere. Our approach is based on the most fundamental principles of tectonics giving understanding that earthquake is an ultimate result of relative movement of tectonic plates and blocks of different sizes. Different kind of gases: methane, helium, hydrogen, and carbon dioxide leaking from the crust can serve as carrier gases for radon including underwater seismically active faults. Radon action on atmospheric gases is similar to the cosmic rays effects in upper layers of atmosphere: it is the air ionization and formation by ions the nucleus of water condensation. Condensation of water vapor is accompanied by the latent heat exhalation is the main cause for observing atmospheric thermal anomalies. Formation of large ion clusters changes the conductivity of boundary layer of atmosphere and parameters of the global electric circuit over the active tectonic faults. Variations of atmospheric electricity are the main source of ionospheric anomalies over seismically active areas. Lithosphere-Atmosphere-Ionosphere Coupling (LAIC) model can explain most of these events as a synergy between different ground surface, atmosphere and ionosphere processes and anomalous variations which are usually named as short-term earthquake precursors. A newly developed approach of Interdisciplinary Space-Terrestrial Framework (ISTF) can provide also a verification of these precursory processes in seismically active regions. The main outcome of this paper is the unified concept for systematic validation of different types of earthquake precursors united by physical basis in one common theory.

  20. Precursor events and self-organization leading to landslide triggering

    Science.gov (United States)

    Lehmann, Peter; Or, Dani

    2010-05-01

    Hillslopes often consist of many interacting soil and land-cover elements differing in hydraulic properties and mechanical strength. Intense rainfall events may result in heterogeneous distribution of hydrologic loading and internal weakening leading to local failure and stress redistribution to neighboring intact units. For certain spatial distributions of hydro-mechanical properties and timing of local failure events, ‘local' failure may propagate across the entire system culminating in landslide release (a ‘global' failure). Such ‘global' event is often preceded by numerous small precursor events (local failures) that theoretically may contain statistical information regarding imminent ‘global' failure and thus could provide certain early warning. We model the system and precursor events by combining concepts of Self-Organized Criticality (SOC) and Fiber Bundle Models (FBM) in a physically-based hydro-mechanical framework. The model consists of hexagonal soil columns connected by fiber bundles at their base and between adjacent elements. Fiber bundles represent mechanical bonds made of numerous connections (fibers) representing friction, roots, cementing agents, water bridges and alike that impart soil strength. Hydrological pathways and load distribution are simulated enabling updating of stresses on fiber bundles. When a bundle fails at element base, stress is redistributed to adjacent connected elements which may initiate a cascade of failures similar to other SOC models (e.g. sand pile model). Increasing hydro-mechanical loads during a rainfall event results in gradual small local fiber failures whose statistics follow a power-law with exponent depending on proximity to global failure. Such state-dependent precursor event statistics could provide a physical basis for field monitoring networks for early warning and hazard prediction. Additionally, the SOC concepts provide a simple framework for landslide susceptibility mapping in space and time and

  1. Molecular analysis of precursor lesions in familial pancreatic cancer.

    Directory of Open Access Journals (Sweden)

    Tatjana Crnogorac-Jurcevic

    Full Text Available With less than a 5% survival rate pancreatic adenocarcinoma (PDAC is almost uniformly lethal. In order to make a significant impact on survival of patients with this malignancy, it is necessary to diagnose the disease early, when curative surgery is still possible. Detailed knowledge of the natural history of the disease and molecular events leading to its progression is therefore critical.We have analysed the precursor lesions, PanINs, from prophylactic pancreatectomy specimens of patients from four different kindreds with high risk of familial pancreatic cancer who were treated for histologically proven PanIN-2/3. Thus, the material was procured before pancreatic cancer has developed, rather than from PanINs in a tissue field that already contains cancer. Genome-wide transcriptional profiling using such unique specimens was performed. Bulk frozen sections displaying the most extensive but not microdissected PanIN-2/3 lesions were used in order to obtain the holistic view of both the precursor lesions and their microenvironment. A panel of 76 commonly dysregulated genes that underlie neoplastic progression from normal pancreas to PanINs and PDAC were identified. In addition to shared genes some differences between the PanINs of individual families as well as between the PanINs and PDACs were also seen. This was particularly pronounced in the stromal and immune responses.Our comprehensive analysis of precursor lesions without the invasive component provides the definitive molecular proof that PanIN lesions beget cancer from a molecular standpoint. We demonstrate the need for accumulation of transcriptomic changes during the progression of PanIN to PDAC, both in the epithelium and in the surrounding stroma. An identified 76-gene signature of PDAC progression presents a rich candidate pool for the development of early diagnostic and/or surveillance markers as well as potential novel preventive/therapeutic targets for both familial and sporadic

  2. Nicotiana benthamiana as a production platform for artemisinin precursors.

    Science.gov (United States)

    van Herpen, Teun W J M; Cankar, Katarina; Nogueira, Marilise; Bosch, Dirk; Bouwmeester, Harro J; Beekwilder, Jules

    2010-12-03

    Production of pharmaceuticals in plants provides an alternative for chemical synthesis, fermentation or natural sources. Nicotiana benthamiana is deployed at commercial scale for production of therapeutic proteins. Here the potential of this plant is explored for rapid production of precursors of artemisinin, a sesquiterpenoid compound that is used for malaria treatment. Biosynthetic genes leading to artemisinic acid, a precursor of artemisinin, were combined and expressed in N. benthamiana by agro-infiltration. The first committed precursor of artemisinin, amorpha-4,11-diene, was produced upon infiltration of a construct containing amorpha-4,11-diene synthase, accompanied by 3-hydroxy-3-methylglutaryl-CoA reductase and farnesyl diphosphate synthase. Amorpha-4,11-diene was detected both in extracts and in the headspace of the N. benthamiana leaves. When the amorphadiene oxidase CYP71AV1 was co-infiltrated with the amorphadiene-synthesizing construct, the amorpha-4,11-diene levels strongly decreased, suggesting it was oxidized. Surprisingly, no anticipated oxidation products, such as artemisinic acid, were detected upon GC-MS analysis. However, analysis of leaf extracts with a non-targeted metabolomics approach, using LC-QTOF-MS, revealed the presence of another compound, which was identified as artemisinic acid-12-β-diglucoside. This compound accumulated to 39.5 mg x kg(-1) fwt. Apparently the product of the heterologous pathway that was introduced, artemisinic acid, is further metabolized efficiently by glycosyl transferases that are endogenous to N. benthamiana. This work shows that agroinfiltration of N. bentamiana can be used as a model to study the production of sesquiterpenoid pharmaceutical compounds. The interaction between the ectopically introduced pathway and the endogenous metabolism of the plant is discussed.

  3. Nicotiana benthamiana as a production platform for artemisinin precursors.

    Directory of Open Access Journals (Sweden)

    Teun W J M van Herpen

    Full Text Available BACKGROUND: Production of pharmaceuticals in plants provides an alternative for chemical synthesis, fermentation or natural sources. Nicotiana benthamiana is deployed at commercial scale for production of therapeutic proteins. Here the potential of this plant is explored for rapid production of precursors of artemisinin, a sesquiterpenoid compound that is used for malaria treatment. METHODOLOGY/PRINCIPAL FINDINGS: Biosynthetic genes leading to artemisinic acid, a precursor of artemisinin, were combined and expressed in N. benthamiana by agro-infiltration. The first committed precursor of artemisinin, amorpha-4,11-diene, was produced upon infiltration of a construct containing amorpha-4,11-diene synthase, accompanied by 3-hydroxy-3-methylglutaryl-CoA reductase and farnesyl diphosphate synthase. Amorpha-4,11-diene was detected both in extracts and in the headspace of the N. benthamiana leaves. When the amorphadiene oxidase CYP71AV1 was co-infiltrated with the amorphadiene-synthesizing construct, the amorpha-4,11-diene levels strongly decreased, suggesting it was oxidized. Surprisingly, no anticipated oxidation products, such as artemisinic acid, were detected upon GC-MS analysis. However, analysis of leaf extracts with a non-targeted metabolomics approach, using LC-QTOF-MS, revealed the presence of another compound, which was identified as artemisinic acid-12-β-diglucoside. This compound accumulated to 39.5 mg x kg(-1 fwt. Apparently the product of the heterologous pathway that was introduced, artemisinic acid, is further metabolized efficiently by glycosyl transferases that are endogenous to N. benthamiana. CONCLUSION/SIGNIFICANCE: This work shows that agroinfiltration of N. bentamiana can be used as a model to study the production of sesquiterpenoid pharmaceutical compounds. The interaction between the ectopically introduced pathway and the endogenous metabolism of the plant is discussed.

  4. Selective Disparity of Ordinary Chondritic Precursors in Micrometeorite Flux

    Science.gov (United States)

    Rudraswami, N. G.; Fernandes, D.; Naik, A. K.; Shyam Prasad, M.; Carrillo-Sánchez, J. D.; Plane, J. M. C.; Feng, W.; Taylor, S.

    2018-01-01

    All known extraterrestrial dust (micrometeoroids) entering the Earth’s atmosphere is anticipated to have a significant contribution from ordinary chondritic precursors, as seen in meteorites, but this is an apparent contradiction that needs to be addressed. Ordinary chondrites represent a minor contribution to the overall meteor influx compared to carbonaceous chondrites, which are largely dominated by CI and/or CM chondrites. However, the near-Earth asteroid population presents a scenario with sufficient scope for generation of dust-sized debris from ordinary chondritic sources. The bulk chemical composition of 3255 micrometeorites (MMs) collected from Antarctica and deep-sea sediments has shown Mg/Si largely dominated by carbonaceous chondrites, and less than 10% having ordinary chondritic precursors. The chemical ablation model is combined with different initial chondritic compositions (CI, CV, L, LL, H), and the results clearly indicate that high-density (≥2.8 g cm‑3) precursors, such as CV and ordinary chondrites in the size range 100–700 μm and zenith angle 0°–70°, ablate at much faster rates and lose their identity even before reaching the Earth’s surface and hence are under-represented in our collections. Moreover, their ability to survive as MMs remains grim for high-velocity micrometeoroids (>16 km s‑1). The elemental ratio for CV and ordinary chondrites are also similar to each other irrespective of the difference in the initial chemical composition. In conclusion, MMs belonging to ordinary chondritic precursors’ concentrations may not be insignificant in thermosphere, as they are found on Earth’s surface.

  5. Tricyclic antidepressant amitriptyline indirectly increases the proliferation of adult dentate gyrus-derived neural precursors: an involvement of astrocytes.

    Directory of Open Access Journals (Sweden)

    Shuken Boku

    Full Text Available Antidepressants increase the proliferation of neural precursors in adult dentate gyrus (DG, which is considered to be involved in the therapeutic action of antidepressants. However, the mechanism underlying it remains unclear. By using cultured adult rat DG-derived neural precursors (ADP, we have already shown that antidepressants have no direct effects on ADP. Therefore, antidepressants may increase the proliferation of neural precursors in adult DG via unknown indirect mechanism. We have also shown that amitriptyline (AMI, a tricyclic antidepressant, induces the expressions of GDNF, BDNF, FGF2 and VEGF, common neurogenic factors, in primary cultured astrocytes (PCA. These suggest that AMI-induced factors in astrocytes may increase the proliferation of neural precursors in adult DG. To test this hypothesis, we examined the effects of AMI-induced factors and conditioned medium (CM from PCA treated with AMI on ADP proliferation. The effects of CM and factors on ADP proliferation were examined with BrdU immunocytochemistry. AMI had no effect on ADP proliferation, but AMI-treated CM increased it. The receptors of GDNF, BDNF and FGF2, but not VEGF, were expressed in ADP. FGF2 significantly increased ADP proliferation, but not BDNF and GDNF. In addition, both of a specific inhibitor of FGF receptors and anti-FGF2 antibody significantly counteracted the increasing effect of CM on ADP proliferation. In addition, FGF2 in brain is mainly derived from astrocytes that are key components of the neurogenic niches in adult DG. These suggest that AMI may increase ADP proliferation indirectly via PCA and that FGF2 may a potential candidate to mediate such an indirect effect of AMI on ADP proliferation via astrocytes.

  6. The influence of cholesterol precursor--desmosterol--on artificial lipid membranes.

    Science.gov (United States)

    Hąc-Wydro, Katarzyna; Węder, Karolina; Mach, Marzena; Flasiński, Michał; Wydro, Paweł

    2015-08-01

    The disorders in cholesterol biosynthesis pathway and various diseases manifest in the accumulation of cholesterol precursors in the human tissues and cellular membranes. In this paper the effect of desmosterol--one of cholesterol precursors--on model lipid membranes was studied. The investigations were performed for binary SM/desmo and POPC/desmo and ternary SM/POPC/desmo monolayers. Moreover, the experiments based on the gradual substitution of cholesterol by desmosterol in SM/POPC/chol=1:1:1 system were done. The obtained results allowed one to conclude that desmosterol is of lower domains promoting and stabilizing properties and packs less tightly with the lipids in monolayers. Moreover, desmosterol probably could replace cholesterol in model membranes, but only at its low proportion in the system (2%), however, at a higher degree of cholesterol substitution a significant decrease of the monolayer stability and packing and alterations in the film morphology were detected. The results collected in this work together with those from previous experiments allowed one to analyze the effect of a double bond in the sterol side chain as well as its position in the ring system on membrane activity of the molecule and to verify Bloch hypothesis. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. REFLECTIVE THINKING AND TEACHING PRACTICES: A PRECURSOR FOR INCORPORATING CRITICAL THINKING INTO THE CLASSROOM?

    Directory of Open Access Journals (Sweden)

    S. Chee Choy

    2012-01-01

    Full Text Available The concept of reflective thinking as a precursor for incorporating critical thinking has been not been adequately researched. Most research has not given any effective strategies on how to incorporate these two concepts. There is a constant need to incorporate critical thinking into the classroom without much success. This study will attempt to show a link between reflective thinking and its ability to stimulate critical thinking. Teachers often perceive that critical thinking skills need to be taught, however research has shown that they may not know how to do this effectively. The use of reflective thinking may be a precursor to stimulating critical thinking in teachers. The research questions are on the reflective thinking skills of teachers and how they perceive themselves and their teaching. In this study a total of 60 participants from institutions of higher learning volunteered to answer a questionnaire to determine the level at which they reflected on their teaching practices as an indicator of their level of critical thinking. It was found that most of the teachers did not reflect deeply on their teaching practices. They did not seem to practice the four learning processes: assumption analysis, contextual awareness, imaginative speculation and reflective scepticism which were indicative of reflection. It would suggest that critical thinking is practised minimally among teachers. Further research need to be carried out on how to bring about reflective practices among teachers and how it would enhance the quality of lessons in terms of critical thinking.

  8. Hydrogeochemical precursors of strong earthquakes in Kamchatka: further analysis

    Directory of Open Access Journals (Sweden)

    P. F. Biagi

    2001-01-01

    Full Text Available For many years, ion and gas content data have been collected from the groundwater of three deep wells in the southern area of the Kamchatka peninsula, Russia. In the last ten years, five earthquakes with M > 6.5 have occurred within 250 km of the wells. In a previous study, we investigated the possibility that the hydrogeochemical time series contained precursors. The technique used was to assume that each signal with an amplitude of three times the standard deviation is an irregularity and we then defined anomalies as irregularities occurring simultaneously in the data for more than one parameter at each well. Using this method, we identified 11 anomalies with 8 of them being possible successes and 3 being failures as earthquake precursors. Precursors were obtained for all five earthquakes that we considered. In this paper, we allow for the cross-correlation found between the gas data sets and in some cases, between the ion data sets. No cross-correlation has been found between gas and ion content data. Any correlation undermines the idea that an anomaly might be identified from irregularities appearing simultaneously on different parameters at each site. To refine the technique, we re-examine the hydrogeochemical data and define as anomalies those irregularities occurring simultaneously only in the data of two or more uncorrelated parameters. We then restricted the analysis to the cases of just the gas content data and the ion content data. In the first case, we found 6 successes and 2 failures, and in the second case, we found only 3 successes. In the first case, the precursors appear only for three of the five earthquakes we considered, and in the second case, only for two, but these are the earthquakes nearest to the wells. Interestingly, it shows that when a strict set of rules for defining an anomaly is used, the method produces only successes and when less restrictive rules are used, earthquakes further from the well are implicated, but

  9. Endophytic fungi as a source of biofuel precursors.

    Science.gov (United States)

    Santos-Fo, Florisvaldo; Fill, Taicia Pacheco; Nakamura, Joanita; Monteiro, Marcos Roberto; Rodrigues-Fo, Edson

    2011-07-01

    Endophytic fungi, isolated from a number of different species of tropical plants, were investigated for lipid biodiesel precursor production. The extracts produced from liquid cultures of these fungi were subjected to acidcatalyzed transesterification reactions with methanol producing methyl esters and then analyzed through chromatographic (GC-FID) and spectrometric techniques (MS, NMR ¹H). The European Standard Method, EN 14103, was used for the quantification of methyl esters extracted from the fungi of the species and genera studied. Xylariaceous fungi exhibited the highest concentrations of methyl esters (91%), and hence may be a promising source for biofuel.

  10. Heteromers of amyloid precursor protein in cerebrospinal fluid

    OpenAIRE

    Cuchillo-Iba?ez, Inmaculada; Lopez-Font, Inmaculada; Boix-Amor?s, Alba; Brinkmalm, Gunnar; Blennow, Kaj; Molinuevo, Jose-Luis; S?ez-Valero, Javier

    2015-01-01

    Background Soluble fragments of the amyloid precursor protein (APP) generated by ?- and ?-secretases, sAPP? and sAPP?, have been postulated as promising new cerebrospinal fluid (CSF) biomarkers for the clinical diagnosis of Alzheimer?s disease (AD). However, the capacity of these soluble proteins to assemble has not been explored and could be relevant. Our aim is to characterize possible sAPP oligomers that could contribute to the quantification of sAPP? and sAPP? in CSF by ELISA, as well as ...

  11. Isotopic and geochemical precursors of earthquakes and volcanic eruptions

    International Nuclear Information System (INIS)

    1993-11-01

    Radon 222 seems to be one of the most promising precursors and is the tracer for which more data are available: according to statistics elaborated in China, 70% of earthquakes are preceded by radon anomalies detectable in soil, air and/or in groundwater. Also other changes of the fluid chemical composition and variations of 3 He/ 4 He, 2 H/ 1 H, 13 C/ 12 C, 18 O/ 16 O isotopic ratios have been detected. Among these indicators one can mention variations in concentration and/or isotopic ratios of hydrogen, helium, carbon, oxygen, neon, radon, radium and uranium. Refs, figs, tabs

  12. A Precursor of Modern Economic Thought: Antoine Laurent de Lavoisier

    Directory of Open Access Journals (Sweden)

    Andreea VASILIU

    2011-02-01

    Full Text Available In the context of development of economic relations, national accounting is a necessity. Building a system of information on gross domestic product, size of national wealth, financial relations and cash flows determine studies on the economic forecast, the distribution and accumulation of national wealth. Efforts in this direction have been numerous and have their roots in the work of Antoine Laurent Lavoisier . He was he who first promulgated the concepts and specific national accounting methods. He was a precursor of modern economic thought.

  13. Polymer precursors for SiC ceramic materials

    Science.gov (United States)

    Litt, Morton H.

    1986-01-01

    Work on precursor polymers to SiC was performed, concentrating on polymers made from decamethyl cyclohexasilyene units. The initial approach was to synthesize mixed diphenyl decamethyl cyclohexasilane, dephenylate, and polymerize. This produced polymers which had yields of up to 50 percent SiC. (Theoretical yield is 75 percent). The present approach is to make the polymer through the intermediate trans-1,4-diphenyl decamethyl cyclohexasilane. This should produce a crystalline polymer and high strength fibers. These will be thermally decomposed to SiC fibers. This requires new chemistry which is currently being studied.

  14. Multifunctional Silica Nanoparticles Modified via Silylated-Decaborate Precursors

    Directory of Open Access Journals (Sweden)

    Fatima Abi-Ghaida

    2015-01-01

    Full Text Available A new class of multifunctional silica nanoparticles carrying boron clusters (10-vertex closo-decaborate and incorporating luminescent centers (fluorescein has been developed as potential probes/carriers for potential application in boron neutron capture therapy (BNCT. These silica nanoparticles were charged in situ with silylated-fluorescein fluorophores via the Stöber method and their surface was further functionalized with decaborate-triethoxysilane precursors. The resulting decaborate dye-doped silica nanoparticles were characterized by TEM, solid state NMR, DLS, nitrogen sorption, elemental analysis, and fluorescence spectroscopy.

  15. Beryllium-10 in Australasian tektites - Evidence for a sedimentary precursor

    Science.gov (United States)

    Pal, D. K.; Moniot, R. K.; Kruse, T. H.; Herzog, G. F.; Tuniz, C.

    1982-01-01

    Each of seven Australasian tektites contains about 100 micron atoms of beryllium-10 (half-life, 1.53 million years) per gram. Cosmic-ray bombardment of the australites cannot have produced the measured amounts of beryllium-10 either at the earth's surface or in space. The beryllium-10 contents of these australites are consistent with a sedimentary precursor that adsorbed from precipitation beryllium-10 produced in the atmosphere. The sediments must have spent several thousand years at the earth's surface within a few million years of the tektite-producing event.

  16. Surface reconstruction precursor to melting in Au309 clusters

    Directory of Open Access Journals (Sweden)

    Fuyi Chen

    2011-09-01

    Full Text Available The melting of gold cluster is one of essential properties of nanoparticles and revisited to clarify the role played by the surface facets in the melting transition by molecular dynamics simulations. The occurrence of elaborate surface reconstruction is observed using many-body Gupta potential as energetic model for 309-atom (2.6 nm decahedral, cuboctahedral and icosahedral gold clusters. Our results reveal for the first time a surface reconstruction as precursor to the melting transitions. The surface reconstruction lead to an enhanced melting temperature for (100 faceted decahedral and cuboctahedral cluster than (111 faceted icosahedral gold cluster, which form a liquid patch due to surface vacancy.

  17. Synthesis of carbon nanotubes using natural carbon precursor: Castor oil

    Science.gov (United States)

    Raziah, A. Z.; Junizah, A. R.; Saifuddin, N.

    2012-09-01

    Castor oil has long been an article of commerce due to its versatility as it is widely used as a starting material for many industrial chemical products because of its unique structure. In this study, carbon nanotubes has been synthesized by thermal decomposition of castor oil in nitrogen atmosphere at 300-400δC using custom-made microwave processing unit. The precursor material was catalyzed by iron clusters originating from the addition of ferrocene. The morphology and characterization of the CNTs were studied and discussed by transmission electron microscopy (TEM).

  18. Survey of volatile oxylipins and their biosynthetic precursors in bryophytes.

    Science.gov (United States)

    Croisier, Emmanuel; Rempt, Martin; Pohnert, Georg

    2010-04-01

    Oxylipins are metabolites which are derived from the oxidative fragmentation of polyunsaturated fatty acids. These metabolites play central roles in plant hormonal regulation and defense. Here we survey the production of volatile oxylipins in bryophytes and report the production of a high structural variety of C5, C6, C8 and C9 volatiles of mosses. In liverworts and hornworts oxylipin production was not as pronounced as in the 23 screened mosses. A biosynthetic investigation revealed that both, C18 and C20 fatty acids serve as precursors for the volatile oxylipins that are mainly produced after mechanical wounding of the green tissue of mosses. Copyright 2009 Elsevier Ltd. All rights reserved.

  19. Patterned Fluorescence Images with Indigo Precursors in Polymer Film

    International Nuclear Information System (INIS)

    Yoon, Bora; Oh, Eun Hae; Lee, Chan Woo; Kim, Jongman

    2013-01-01

    We have developed a new strategy for the generation of patterned fluorescence images in polymer film. A fluorescent acetyl protected indole 6 was transformed to a nonfluorescent indigo dye 7 by UV irradiation. In addition, a t-Boc protected fluorescent indigo molecule 8 was also converted to a nonfluorescent indigo derivative 7 under a chemical amplification condition. Photomasked UV irradiation of the precursor molecules allowed efficient generation of patterned fluorescence images in polymer film. The strategy described in current investigation is believed to be an important addition to the fluorescent patterning technology

  20. Patterned Fluorescence Images with Indigo Precursors in Polymer Film

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Bora; Oh, Eun Hae; Lee, Chan Woo; Kim, Jongman [Hanyang Univ., Seoul (Korea, Republic of)

    2013-04-15

    We have developed a new strategy for the generation of patterned fluorescence images in polymer film. A fluorescent acetyl protected indole 6 was transformed to a nonfluorescent indigo dye 7 by UV irradiation. In addition, a t-Boc protected fluorescent indigo molecule 8 was also converted to a nonfluorescent indigo derivative 7 under a chemical amplification condition. Photomasked UV irradiation of the precursor molecules allowed efficient generation of patterned fluorescence images in polymer film. The strategy described in current investigation is believed to be an important addition to the fluorescent patterning technology.