Structural features of lignohumic acids

Czech Academy of Sciences Publication Activity Database

Novák, František; Šestauberová, Martina; Hrabal, R.

2015-01-01

Roč. 1093, August (2015), s. 179-185 ISSN 0022-2860 Institutional support: RVO:60077344 Keywords : C-13 NMR * FTIR * humic acids * lignohumate * lignosulfonate * structure Subject RIV: DF - Soil Science Impact factor: 1.780, year: 2015

Physico-mechanical properties of plywood bonded with ecological adhesives from Acacia mollissima tannins and lignosulfonates

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Rhazi, Naima; Oumam, Mina; Sesbou, Abdessadek; Hannache, Hassan; Charrier-El Bouhtoury, Fatima

2017-06-01

The objective of this research was to develop ecological adhesives for bonding plywood panels using lignosulfonates, a common waste product of the wood pulp industry, and natural tannin extracted from Moroccan bark of Acacia mollissima using different process. Natural tannin and lignin were used in wood adhesives formulation to substitute resins based on phenol and formaldehyde. To achieve this, the lignosulfonates were glyoxalated to enhance their reactivity and the used tannins obtained by three different extraction methods were compared with commercial mimosa tannin. The proportion of Acacia mollissima tannins and lignosulfonates, the pressing time, the pressing temperature, and the pressure used were studied to improve mechanical properties, and bonding quality of plywood panel. The properties of plywood panels produced with these adhesives were tested in accordance with normative tests. Thus, the tensile strength, and the shear strength were measured. The results showed that the performance of the plywood panels made using biobased tannin adhesives was influenced by physical conditions such as pressure, press temperature as well as by chemical conditions, such as the tannin-lignin ratio. It exhibited excellent mechanical properties comparable to commercially available phenol-formaldehyde plywood adhesives. This study showed that biobased adhesives formulations presented good and higher mechanical performance and no formaldehyde emission. Contribution to the topical issue "Materials for Energy harvesting, conversion and storage II (ICOME 2016)", edited by Jean-Michel Nunzi, Rachid Bennacer and Mohammed El Ganaoui

In vitro Dissolution Studies on Solid Dispersions of Mefenamic Acid.

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Rao, K R S Sambasiva; Nagabhushanam, M V; Chowdary, K P R

2011-03-01

Solid dispersions of mefanamic acid with a water-soluble polymer polyvinyl pyrrolidine and a super disintegrant, primojel were prepared by common solvent and solvent evaporation methods employing methanol as the solvent. The dissolution rate and dissolution efficiency of the prepared solid dispersions were evaluated in comparison to the corresponding pure drug. Solid dispersions of mefenamic acid showed a marked enhancement in dissolution rate and dissolution efficiency. At 1:4 ratio of mefenamic acid-primojel a 2.61 fold increase in the dissolution rate of mefenamic acid was observed with solid dispersion. The solid dispersions in combined carriers gave much higher rates of dissolution than super disintegrants alone. Mefanamic acid-primojel-polyvinyl pyrrolidine (1:3.2:0.8) solid dispersion gave a 4.11 fold increase in the dissolution rate of mefenamic acid. Super disintegrants alone or in combination with polyvinyl pyrrolidine could be used to enhance the dissolution rate of mefenamic acid.

Preparation and properties of blends composed of lignosulfonated layered double hydroxide/plasticized starch and thermoplastics.

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Privas, Edwige; Leroux, Fabrice; Navard, Patrick

2013-07-01

Layered double hydroxide prepared with lignosulfonate (LDH/LS) can be easily dispersed down to the nanometric scale in thermoplastic starch, at concentration of 1 up to 4 wt% of LDH/LS. They can thus be used as a bio-based reinforcing agent of thermoplastic starch. Incorporation of LDH/LS in starch must be done using LDH/LS slurry instead of powder on order to avoid secondary particles aggregation, the water of the paste being used as the starch plasticizer. This reinforced starch was used for preparing a starch-polyolefine composite. LDH/LS-starch nanocomposites were mixed in a random terpolymer of ethylene, butyl acrylate (6%) and maleic anhydride (3%) at concentrations of 20 wt% and 40 wt%. With a 20% loading of (1 wt% LDH/LS in thermoplastic starch), the ternary copolymer is partially bio-based while keeping nearly its original processability and mechanical properties and improving oxygen barrier properties. The use of layered double hydroxides is also removing most odours linked to the lignin phase. Copyright © 2013 Elsevier Ltd. All rights reserved.

FORMULATION AND EVALUATION OF MEFENAMIC ACID SOLID DISPERSIONS USING PEG-4000

OpenAIRE

Shaik Jamal Shariff; Shaik Saleem; Alaparthi Naga Pavan Kumar; Bachupally Ajay Kumar; Punuru Madhusudhan

2013-01-01

Mefenamic acid (MA) solid Dispersions were prepared employing methanol as a common solvent using PEG-4000 as a drug carrier with two different techniques namely, melting method and solvent evaporation in varied ratios. The prepared solid dispersions were evaluated and compared with that of pure drug (mefenamic acid) in respect to the dissolution rate and dissolution efficiency. It is noted that solid dispersions of mefenamic acid showed a remarkable increase in dissolution rate and dissolutio...

Evaluation of a Naturally-derived Deflocculant (Terminalia Chebula in Bentonite Dispersions

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Jalal Neshat

2016-04-01

Full Text Available The unwanted addition of salt to drilling causes flocculation which has an adverse effect on mud rheological properties. To treat the flocculated mud chemical, deflocculants are commonly used; however, their disadvantages such as negative environmental effects, lower tolerance to contamination, and toxicity motivated scientists to search for effective additives. Using plant derived additives instead of commercial additives could help resolve the mentioned weaknesses, because they are nontoxic, cheap, easily accessible, and act multi-functional. In this paper the effect of black myrobalan rheological properties of flocculated bentonite mud was investigated and its performance was compared with chrome lignosulfonate (CLS. Rheological and filtration tests were conducted and properties such as plastic viscosity, yield point, gel strength, thixotropy, and apparent viscosity were calculated. It was perceived that by increasing black myrobalan concentration to 0.6 wt.%, rheological parameters and filtration loss decreased by 50% and 66.3% respectively, but they increased at higher concentrations, which indicated that black myrobalan acted as a deflocculant up to 0.6 wt.%. The deflocculation behavior of black myrobalan at low concentrations is attributed to ellagitannic acid and tannic acid. The comparison of the enactment of black myrobalan with chrome lignosulfonate showed that black myrobalan had a stronger decreasing effect on the rheological parameters and filtration compared to CLS.

Zinc transformations in acidic soil and zinc efficiency on maize by adding six organic zinc complexes.

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López-Valdivia, L M; Fernández, M D; Obrador, A; Alvarez, J M

2002-03-13

Experiments under laboratory and greenhouse conditions were conducted to study the response of maize (Zea mays L.) to Zn fertilizer applications (Zn-phenolate, Zn-EDDHA, Zn-EDTA, Zn-lignosulfonate, Zn-polyflavonoid, and Zn-heptagluconate) in an Aquic Haploxeralf soil. The application of Zn complexes significantly increased Zn uptake by the plant compared with that in the control soil. The highest enhancements were obtained in soil treated with Zn-EDTA, Zn-lignosulfonate, and Zn-EDDHA. The highest percentages of Zn taken up by the plants occurred when 20 mg x kg(-1) Zn was applied as Zn-EDTA fertilizer and 10 mg x kg(-1) as Zn-lignosulfonate fertilizer. In the greenhouse experiment, Zn speciation in soil after harvesting showed that almost all Zn was found in the residual fraction followed by metal in the water-soluble plus exchangeable fraction and metal bound to organic matter. The most effective fertilizers maintaining Zn in the most labile fractions were Zn-phenolate, Zn-EDTA, and Zn-lignosulfonate. Conversely, in the incubation experiment, only a small percentage of Zn was found in the water-soluble plus exchangeable fraction and no differences in the Zn distribution were observed between the different fertilizer treatments. The micronutrient content in maize was positively correlated with the water-soluble plus exchangeable Zn as well as with the available Zn determined by the diethylenetriaminepentaacetic acid and Mehlich-3 methods, in the greenhouse experiment. Results of this study showed that the incubation experiment in acidic soil is not a suitable tool to establish the different effectiveness of Zn chelates in plants.

Lignosulfonic acid exhibits broadly anti-HIV-1 activity--potential as a microbicide candidate for the prevention of HIV-1 sexual transmission.

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Min Qiu

Full Text Available Some secondary metabolites from plants show to have potent inhibitory activities against microbial pathogens, such as human immunodeficiency virus (HIV, herpes simplex virus (HSV, Treponema pallidum, Neisseria gonorrhoeae, etc. Here we report that lignosulfonic acid (LSA, a polymeric lignin derivative, exhibits potent and broad activity against HIV-1 isolates of diverse subtypes including two North America strains and a number of Chinese clinical isolates values ranging from 21.4 to 633 nM. Distinct from other polyanions, LSA functions as an entry inhibitor with multiple targets on viral gp120 as well as on host receptor CD4 and co-receptors CCR5/CXCR4. LSA blocks viral entry as determined by time-of-drug addiction and cell-cell fusion assays. Moreover, LSA inhibits CD4-gp120 interaction by blocking the binding of antibodies specific for CD4-binding sites (CD4bs and for the V3 loop of gp120. Similarly, LSA interacts with CCR5 and CXCR4 via its inhibition of specific anti-CCR5 and anti-CXCR4 antibodies, respectively. Interestingly, the combination of LSA with AZT and Nevirapine exhibits synergism in viral inhibition. For the purpose of microbicide development, LSA displays low in vitro cytotoxicity to human genital tract epithelial cells, does not stimulate NF-κB activation and has no significant up-regulation of IL-1α/β and IL-8 as compared with N-9. Lastly, LSA shows no adverse effect on the epithelial integrity and the junctional protein expression. Taken together, our findings suggest that LSA can be a potential candidate for tropical microbicide.

Evaluation of performance of modified sodium lignosulfonate additives as reinforcing agent in porcelain stoneware tiles

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Rastelli, E.

2010-10-01

Full Text Available A sodium salt of a modified lignosulfonate at different percentages was added to a porcelain stoneware suspension and the effects on the rheological properties of slips and on the mechanical properties of prepared samples were investigated. As the presence of sulfonates groups can change the stability of dispersion, a rheological characterisation was necessary to find the critical concentration to obtain well dispersed suspensions and high MOR values. The suspensions stability was tested by oscillatory measurements and the increase of elastic modulus in the suspension corresponded to a MOR and to Young’s modulus increase as well. Finally, to explain the results obtained by the mechanical characterisation of the prepared samples, a model drawing on the composite materials experience, is suggested.

Usando distintos porcentajes, se añadió sal de sodio de un lignosulfonato modificado, a una suspensión de gres porcelánico, y se investigaron los efectos sobre las propiedades reológicas de las suspensiones y sobre las propiedades mecánicas de las muestras preparadas. Debido a que la presencia de grupos de sulfonatos puede modificar la estabilidad de la dispersión, fue necesario realizar una caracterización reológica para averiguar la concentración crítica necesaria para la obtención de suspensiones bien dispersas y altos valores de MOR. Se analizó la estabilidad de las suspensiones por medio de mediciones oscilatorias y el incremento del módulo elástico en la suspensión que corresponde al incremento de un módulo MOR y de un módulo de Young también. Finalmente, para explicar los resultados obtenidos por medio de la caracterización mecánica de las muestras preparadas, se sugiere un modelo que parte de la experiencia con los materiales compuestos.

The removal of fatty acids from edible oil : removal of the dispersed phase of a water-in-oil dispersion by a hydrophilic membrane

NARCIS (Netherlands)

Keurentjes, J.T.F.; Doornbusch, G.I.; Riet, van 't K.

1991-01-01

Fatty acids can be extracted from an oil phase by forming a dispersed phase of saponified fatty acids/water/isopropanol in oil. This dispersion can be separated in the two phases by two membranes of opposite polarity in series. In this study the separation of the water phase from the dispersion by a

Fluorescent pH-Sensing Probe Based on Biorefinery Wood Lignosulfonate and Its Application in Human Cancer Cell Bioimaging.

Science.gov (United States)

Xue, Yuyuan; Liang, Wanshan; Li, Yuan; Wu, Ying; Peng, Xinwen; Qiu, Xueqing; Liu, Jinbin; Sun, Runcang

2016-12-28

A water-soluble, ratiometric fluorescent pH probe, L-SRhB, was synthesized via grafting spirolactam Rhodamine B (SRhB) to lignosulfonate (LS). As the ring-opening product of L-SRhB, FL-SRhB was also prepared. The pH-response experiment indicated that L-SRhB showed a rapid response to pH changes from 4.60 to 6.20 with a pK a of 5.35, which indicated that L-SRhB has the potential for pH detection of acidic organelle. In addition, the two probes were internalized successfully by living cells through the endocytosis pathway and could distinguish normal cells from cancer cells by different cell staining rates. In addition, L-SRhB showed obvious cytotoxicity to cancer cells, whereas it was nontoxic to normal cells in the same condition. L-SRhB might have potential in cancer therapy. L-SRhB might be a promising ratiometric fluorescent pH sensor and bioimaging dye for the recognition of cancer cells. The results also provided a new perspective to the high-value utilization of lignin.

Improvement of CNT dispersion in HDPE by acid and octadecylamine functionalizations

International Nuclear Information System (INIS)

Menezes, Beatriz Rossi Canuto de; Ferreira, Filipe Vargas; Franceschi, Wesley; Brito, Felipe Sales; Nunes, Evelyn Alves; Rodrigues, Karla Faquine; Cividanes, Luciana de Simone; Thim, Gilmar Patrocínio; Rosa, Cintia

2016-01-01

Full text: Since their discovery in 1991, carbon nanotubes (CNTs) have attracted great attention due to their extraordinary structure and exceptional mechanical properties that make them a suitable candidate for polymer-based nanocomposites reinforcement [1]. However, CNTs full potential can only be achieved with a proper dispersion in the matrix, that depends of Van der Waals interactions among CNTs due to the large surface area and the small size. These interactions decrease the CNT dispersion due to the formation of agglomerates. In order to overcome this limitation, surface functionalization with acid and alkyl groups has been used to increase the CNTs dispersion and compatibility with polymer matrix [2]. Therefore, the focus of the present work is to improve the dispersion of CNTs in high density polyethylene (HDPE) matrix through their functionalization with acid (H 2 SO 4 +HNO 3 ) and octadecylamine (ODA:CH 3 (CH 2 ) 17 NH 2 ). The CNT/HDPE nanocomposites (0.8%wt of CNTs) were prepared by mechanical agitation of the melted mixture of CNTs and HDPE and subsequent compression molding. Three nanocomposites were prepared: (1) HDPE + pristine CNTs, (2) HDPE + acid functionalized CNTs, and (3) HDPE + ODA functionalized CNTs. In order to confirm the surface treatment, CNTs was characterized by FT-IR, XPS, Raman, and TEM. The improvement in CNTs dispersion and compatibility with HDPE was verified by tensile test, microhardness, SEM-FEG. The results showed an improvement in the CNTs dispersion for HDPE with acid and ODA functionalized CNTs. The Young's modulus and Vickers microhardness increased significantly for HDPE with treated CNTs when compared with pristine CNTs. References: [1] S Iijima, Nature 354, 56-58 (1991). [2] R Ansari, S Ajori, S Rouhi, Appl Surf Sci 332, 640-647 (2015). (author)

Effect of Acid Oxidation on the Dispersion Property of Multiwalled Carbon Nanotubes

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Goh, P. S.; Ismail, A. F.; Aziz, M.

2009-06-01

A means of dispersion of multiwalled carbon nanotube (MWCNT) via mixed acid (HNO3 and H2SO4) oxidation with different treatment durations was investigated through the solubility study of the treated carbon nanotubes in some common solvents. Fourier transformed infrared (FTIR) characterization of the reaction products revealed that the surface of MWCNTs was successfully functionalized with surface acidic groups. The acid-base titration demonstrated that the amount of surface acidic groups increased in parallel with the refluxing duration. The acid modified MWCNTs were found to be well dispersed in polar solvents, such as ethanol and water due to the presence of the hydrophilic acid functional groups on the surface of raw MWCNTs. Such chemical modification of carbon nanotube properties will pave the way towards the realistic applications in the nanotechnology world.

Clozapine-carboxylic acid plasticized co-amorphous dispersions: Preparation, characterization and solution stability evaluation

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Ali Ahmed Mahmoud Abdelhaleem

2015-06-01

Full Text Available This study addressed the possibility of forming of co-amorphous systems between clozapine (CZ and various carboxylic acid plasticizers (CAPs. The aim was to improve the solubility and oral bioavailability of clozapine. Co-amorphous dispersions were prepared using modified solvent evaporation methodology at drug/plasticizer stoichiometric ratios of 1:1, 1:1.5 and 1:2. Solid state characterization was performed using differential scanning calorimetry, X-ray diffraction and infra red spectroscopy. Highly soluble homogeneous co-amorphous dispersions were formed between clozapine and CAPs via hydrogen bonding. The co-amorphous dispersions formed with tartaric acid (1:2 showed the highest dissolution percentage (> 95 % in 20 minutes compared to pure crystalline CZ (56 %. Highly stable solutions were obtained from co-amorphous CZ-citric and CZ-tartaric acid at 1:1.5 molar ratio. The prepared dispersions suggest the possibility of peroral or sublingual administration of highly soluble clozapine at a reduced dose with the great chance to bypass the first pass metabolism.

Acid functionalized, highly dispersed carbonaceous spheres: an effective solid acid for hydrolysis of polysaccharides

International Nuclear Information System (INIS)

Jiang Yijun; Li Xiutao; Cao Quan; Mu Xindong

2011-01-01

Highly dispersed carbonaceous spheres with sulfonic acid groups were successfully prepared from glucose by hydrothermal method. Transmission electron microscopy (TEM) showed the as-synthesized carbonaceous materials were uniform, spherical in shape with an average diameter of about 450 nm. Fourier transform infrared (FT-IR) proved that –SO 3 H, –COOH, OH groups were grafted on the surface of the carbonaceous spheres during the sulfonation. Interestingly, the functionalized carbonaceous spheres exhibited high dispersibility in the polar solvent due to the hydrophilic groups on the surface. The mechanism of the formation for the carbonaceous spheres was also discussed based on the analysis of structure and composition. At last, the functionalized carbonaceous spheres were employed as solid acid to hydrolyze starch and cellulose. By comparison, the as-synthesized catalyst showed considerable high yield of glucose.

Acid functionalized, highly dispersed carbonaceous spheres: an effective solid acid for hydrolysis of polysaccharides

Science.gov (United States)

Jiang, Yijun; Li, Xiutao; Cao, Quan; Mu, Xindong

2011-02-01

Highly dispersed carbonaceous spheres with sulfonic acid groups were successfully prepared from glucose by hydrothermal method. Transmission electron microscopy (TEM) showed the as-synthesized carbonaceous materials were uniform, spherical in shape with an average diameter of about 450 nm. Fourier transform infrared (FT-IR) proved that -SO3H, -COOH, OH groups were grafted on the surface of the carbonaceous spheres during the sulfonation. Interestingly, the functionalized carbonaceous spheres exhibited high dispersibility in the polar solvent due to the hydrophilic groups on the surface. The mechanism of the formation for the carbonaceous spheres was also discussed based on the analysis of structure and composition. At last, the functionalized carbonaceous spheres were employed as solid acid to hydrolyze starch and cellulose. By comparison, the as-synthesized catalyst showed considerable high yield of glucose.

Dispersion state and humic acids concentration-dependent sorption of pyrene to carbon nanotubes

NARCIS (Netherlands)

Zhang, X.; Kah, M.; Jonker, M.T.O.; Hofmann, T.

2012-01-01

Sonication and humic acids (HA) are known to disperse carbon nanotube (CNT) suspensions, but potential effects on sorption of chemicals to CNTs remain poorly understood. We applied a passive sampling method to investigate the influence of dispersion/aggregation on sorption of pyrene to CNTs.

Dispersion of carbon nanotubes and polymer nanocomposite fabrication using trifluoroacetic acid as a co-solvent

International Nuclear Information System (INIS)

Chen Hui; Muthuraman, Harish; Stokes, Paul; Zou Jianhua; Liu Xiong; Wang, Jinhai; Huo Qun; Khondaker, Saiful I; Zhai Lei

2007-01-01

We herein report the dispersion of multi-walled carbon nanotubes (MWCNTs) using trifluoroacetic acid (TFA) as a co-solvent. TFA is a strong but volatile acid which is miscible with many commonly used organic solvents. Our study demonstrates that MWCNTs can be effectively purified and readily dispersed in a range of organic solvents including dimethyl formamide (DMF), tetrahydrofuran (THF), and dichloromethane when mixed with 10 vol.% trifluoroacetic acid (TFA). X-ray photoelectron spectroscopic analysis revealed that the chemical structure of the TFA-treated MWCNTs remained intact without oxidation. The dispersed carbon nanotubes in TFA/THF solution were mixed with poly(methyl methacrylate) (PMMA) to fabricate polymer nanocomposites. A good dispersion of nanotubes in solution and in polymer matrices was observed and confirmed by SEM, optical microscopy, and light transmittance study. Low percolation thresholds of electrical conductivity were observed from the fabricated MWCNT/PMMA composite films. Further enhancement in the dispersion of MWCNTs was achieved by adding a conjugated conducting polymer, poly(3-hexylthiophene) (P3HT), to the dispersion, wherein TFA also serves as a doping agent to the conducting polymer. The ternary nanocomposite MWCNT/P3HT/PMMA exhibited an extremely low percolation threshold of less than 0.006 wt% of MWCNT content. This low percolation threshold is attributed to a good dispersion of MWCNTs and enhanced conductivity of the nanocomposites by conjugated conducting polymer

INVESTIGATION OF THE PHARMACO-TECHNOLOGICAL PROPERTIES OF SOLID DISPERSIONS OF THIOCTIC ACID, OBTAINED BY MICRONIZATION

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Kovalevska, I. V.

2018-04-01

Full Text Available Introduction. Thioctic acid is used in the treatment of diseases that are characterized by lack of mitochondrial activity, which is responsible for the formation of free radicals. Widespread use of thioctic acid is due to the chemical structure. The thioctic acid exhibits biological activity in both hydrophilic and hydrophobic environments. Thioctic acid is an enzyme cofactor and a powerful antioxidant, it regulates the transcription of numerous genes, participates in regulation of glucose and lipid metabolism, increases insulin sensitivity, and forms complexes with heavy metals. Thioctic acid has a high pharmacological potential, which is confirmed by the evidence base of clinical trials. An analysis of the literature on the oral use of thioctic acid indicates that solid dosage forms can be used for long-term therapy. This route of administration is limited by factors such as reduced solubility in acidic environments and enzymatic degradation. For this reason, the search for various compositions of auxiliary substances and methods of obtaining drugs is an urgent task of pharmaceutical technology. Material & methods. Objects of study were solid dispersions of thioctic acid (SDTA on the basis of cellulose derivatives: microcrystalline (MCC, HPMC (hydroxypropyl methylcellulose and polyvinylpyrrolidone (PVP as compared to thioctic acid (TA. The samples were made by solid phase method using micronization in a laboratory shredder at a ratio of 1: 1. Pharmacological and technological parameters were determined according to generally accepted methods. Results & discussion. In appearance the resulting mixtures had lemon color, without inclusions and the formation of conglomerates, with homogeneous sized particles According to the pharmaco-technological studies, the samples do not have a satisfactory flowability. The values of the Carr index and the ratio of Hausner make it possible to conclude that there is a large force of cohesion between the

High-value utilization of eucalyptus kraft lignin: Preparation and characterization as efficient dye dispersant.

Science.gov (United States)

Zhang, Hui; Yu, Boming; Zhou, Wanpeng; Liu, Xinxin; Chen, Fangeng

2018-04-01

The dark color of industrial lignin is the main obstacle for their high value-added use in areas such as dyestuff dispersants. A kind of light-colored lignosulfonate with favorable dispersibility and remarkable stain resistance is prepared using fractionated eucalyptus kraft lignin. The fractionated lignins named as D (insoluble part) and X (soluble part) and sulfonated lignin fractions named as SD and SX are characterized by FTIR spectroscopy, 1 H NMR spectroscopy, GPC and brightness test. The results reveal that fraction X presents a lower molecular weight but a higher hydroxyl content than that of fraction D, which lead to the differences on the SO 3 H content, dispersibility and color performance of SD and SX. The sulfonated fractions perform a similar molecular weight to that of unsulfonated lignins and show light color due to the phenolic hydroxyl blocking of 1,4-BS (1,4-butane sultone) and the postprocessing of sodium borohydride. The SX that performs the best of all exhibits obvious decrease on phenolic hydroxyl groups and increase on brightness value which is improved by 85.8% compared with control sample. The SX reaches the highest level (grade 5) in the dispersibility test and presents remarkable stain resistance on different textiles, especially on the dacron and cotton. Copyright © 2017 Elsevier B.V. All rights reserved.

The graft polymers from different species of lignin and acrylic acid: synthesis and mechanism study.

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Ye, De zhan; Jiang, Li; Ma, Chao; Zhang, Ming-hua; Zhang, Xi

2014-02-01

The influence of lignin species on the grafting mechanism of lignosulfonate (from eucalyptus and pine, recorded as HLS and SLS, respectively) with acrylic acid (AA) was investigated. The graft polymers were confirmed by the absorption of carbonyl groups in the FTIR spectra. The decreasing phenolic group's content (Ph-OH) is not only due to its participation as grafting site but also to the negative effect of initiator. In the initial period (0-60 min), HLS and SLS both accelerate the polymerization of AA. Additionally, Ph-OH group's content is proportional to product yield (Y%), monomer conversion (C%) and grafting efficiency (GE%), strongly indicating that it acts as active center. Nevertheless, compared with HLS, Y% and C% in SLS grafting system are lower though it has higher Ph-OH group's content, which is due to the quinonoid structure formed by the self-conjugated of phenoxy radical in Guaiacyl unit. Finally, the lignosulfonate grafting mechanism was proposed. Copyright © 2013 Elsevier B.V. All rights reserved.

Spontaneous dispersion of PdO onto acid sites of zeolites studied by in situ DXAFS

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Okumura, K; Niwa, M; Yokota, S; Kato, K; Tanida, H; Uruga, T

2003-01-01

The generation of highly dispersed PdO over zeolite supports was studied using in situ energy-dispersive XAFS (DXAFS) technique. From the comparison with the Na-ZSM-5, it was found that the oxidation as well as the spontaneous dispersion of Pd was promoted through the interaction between PdO and acid sites of H-form zeolites. (author)

Corrosion Prevention of Cold Rolled Steel Using Water Dispersible Lignosulfonic Acid Doped Polyaniline

Science.gov (United States)

Viswanathan, Tito (Inventor)

2007-01-01

The invention provides coatings useful for preventing corrosion of metals. The coatings comprise a film-forming resin and conductive polymers comprising linearly conjugated x-systems and residues of sulfonated lignin or a sulfonated polyflavonoid or derivatives of solfonated lignin or a sulfonated polyflavonoid. The invention also provides a latex formulation of the coatings, and articles of manufacture comprising a metal substrate and a coating in contact with the metal substrate.

Influence of expander components on the processes at the negative plates of lead-acid cells on high-rate partial-state-of-charge cycling. Part I: Effect of lignosulfonates and BaSO{sub 4} on the processes of charge and discharge of negative plates

Energy Technology Data Exchange (ETDEWEB)

Pavlov, D.; Nikolov, P.; Rogachev, T. [Institute of Electrochemistry and Energy Systems, Bulgarian Academy of Sciences, Acad. Georgi Bonchev Street, bl. 10, Sofia 1113 (Bulgaria)

2010-07-15

This study investigates the influence of the organic expander component (Vanisperse A) and of BaSO{sub 4} on the performance of negative lead-acid battery plates on high-rate partial-state-of-charge (HRPSoC) cycling. Batteries operating in the HRPSoC mode should be classified as a separate type of lead-acid batteries. Hence, the additives to the negative plates should differ from the conventional expander composition. It has been established that lignosulfonates are adsorbed onto the lead surface and thus impede the charge processes, which results in impaired reversibility of the charge-discharge processes and hence shorter cycle life on HRPSoC operation, limited by sulfation of the negative plates. BaSO{sub 4} exerts the opposite effect: it improves the reversibility of the processes in the HRPSoC mode and hence prolongs the cycle life of the cells. The most pronounced effect of BaSO{sub 4} has been registered when it is added in concentration of 1.0 wt.% versus the leady oxide (LO) used for paste preparation. It has also been established that BaSO{sub 4} lowers the overpotential of PbSO{sub 4} nucleation. The results of the present investigation indicate that BaSO{sub 4} affects also the crystallization process of Pb during cell charging. Thus, BaSO{sub 4} eventually improves the performance characteristics of lead-acid cells on HRPSoC cycling. (author)

Process for the reduction of nitrogen oxides in an effluent

Energy Technology Data Exchange (ETDEWEB)

Epperly, W.R.; Sullivan, J.C.; Sprague, B.N.

1989-07-04

This patent describes a process for the reduction of the concentration of nitrogen oxides in the effluent from the combustion of a carbonaceous fuel. The process comprises introducing a treatment agent which comprises a composition selected from the group consisting of NH/sub 4/-lignosulfonate, calcium lignosulfonate, 2-furoic acid, 1,3 dioxolane, tetrahydrofuran, furfurylamine, furfurylalcohol, gluconic acid, citric acid, n-butyl acetate, 1,3 butylene glycol, methylal, tetrahydrofuryl alcohol, furan, fish oil, coumalic acid, furfuryl acetate, tetrahydrofuran 2,3,4,5-tetracarboxylic acid, tetrahydrofurylamine, furylacrylic acid, tetrahydropyran, 2,5-furandimethanol, mannitol, hexamethylenediamine, barbituric acid, acetic anhydride, oxalic acid, mucic acid and d-galactose.

Preparation of highly dispersed palladium–phosphorus nanoparticles and its electrocatalytic performance for formic acid electrooxidation

International Nuclear Information System (INIS)

Sun Hanjun; Xu Jiangfeng; Fu Gengtao; Mao Xinbiao; Zhang, Lu; Chen Yu; Zhou Yiming; Lu Tianhong; Tang Yawen

2012-01-01

Highly dispersed and ultrafine palladium–phosphorus (Pd–P) nanoparticles (NPs) are prepared with a novel phosphorus reduction method. The structural and electronic properties of Pd–P NPs are characterized using Fourier transform infrared (FT-IR), energy dispersive spectrometer (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The electrooxidation of formic acid on Pd–P NPs are investigated by using cyclic voltammetry, chronoamperometry and CO-stripping measurements. The physical characterizations indicate the doped P element can enhance the content of Pd 0 species in Pd NPs, decrease the particle size and improve the dispersion of Pd–P NPs. The electrochemical measurements show the Pd–P NPs have a better catalytic performance for formic acid electrooxidation than Pd NPs.

Utilização de ligninas em resinas fenólicas: 1. Preparação de novolacas a partir de lignossulfonatos Use of lignins in phenolic resins: 1. Preparation of novolacs from lignosulfonates 49

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Fernando dos Santos

1999-01-01

Full Text Available Este trabalho descreve uma utilização mais nobre para a lignina obtida de processos industriais de polpação. Foram preparadas resinas fenólicas tipo novolaca, utilizando-se lignossulfonato de amônio e lignossulfonato de sódio (com diferentes teores de açúcares residuais como correagentes, em substituição parcial ao fenol. As resinas foram preparadas mantendo-se o processo utilizado industrialmente. As resinas foram caracterizadas por análises químicas, quanto à distribuição de massa molar e análises térmicas. As resinas preparadas com lignossulfonatos apresentaram maior reatividade com hexametilenotetramina (agente de reticulação. Isto é uma vantagem, pois pode-se ter ciclos de moldagem de peças mais curtos, o que economicamente é favorável.This work describes the production of high value products using lignins obtained from industrial pulping processes. Novolac phenolic resins were prepared employing ammonium lignosulfonates and sodium lignosulfonates (with different residual sugar contents in a partial replacement of phenol. The resins were prepared using the same conditions employed in the industrial phenolic resins production. The lignin based resins were characterized by chemical analysis, molecular weight distribution and thermal analysis. The resins prepared using lignosulfonates showed higher reactivity with hexamethylenetetramine (crosslink agent. This behavior lead to another economic advantage as consequence of the reduction in the expended time for molding cycles.

Microwave-assisted synthesis of transition metal phosphide

Science.gov (United States)

Viswanathan, Tito

2014-12-30

A method of synthesizing transition metal phosphide. In one embodiment, the method has the steps of preparing a transition metal lignosulfonate, mixing the transition metal lignosulfonate with phosphoric acid to form a mixture, and subjecting the mixture to a microwave radiation for a duration of time effective to obtain a transition metal phosphide.

Preparation of Biocomposites using Sawdust and Lignosulfonate with a Culturе Liquid of Levan Producer Azotobacter vinelandii as a Bonding Agent

Directory of Open Access Journals (Sweden)

Victor V. Revin

2016-02-01

Full Text Available The possibility of preparing molding-bioengineered materials, such as woodchip boards (WCB, from sawdust using technical lignosulfonate (LGS, a wood waste product, and a culture liquid (CL of levan microbial polysaccharide producer by Azotobacter vinelandii D-08 is explored in this article. The parameters of the derived materials are comparable to those of traditional materials made from toxic phenol-formaldehyde resins. The various physical and mechanical characteristics of the materials depend on the quantity of the bonding agent used for the preparation. Adding a culture liquid increases the humidity resistance of the molding materials. Using electron microscopy and X-ray micro-tomography, it is clear that the structure of woodchip boards become more homogeneous without microcracks with the addition of CL. The strength of the best samples prepared was approximately 24 to 29 MPa with a density of 1170 to 1255 kg/m3 and a swell on wetting of 6.7%. During hot pressing, noticeable changes were observed by Fourier transform infrared spectroscopy (FTIR at frequencies typical of LGS sulfonic-acid groups, levan fructose fragments, and skeletal vibrations of a syringal/guaiacyl core in lignin and of C-H groups of hemicelluloses. This indicates the involvement of these functional groups in the process of binding wood particles with hot pressing.

Adsorption of polymethacrylic acid from aqueous solutions on disperse titanium dioxide

Science.gov (United States)

Yaremko, Z. M.; Tkachenko, N. G.; Fedushinskaya, L. B.

2011-10-01

The state of macromolecules of polymethacrylic acid adsorbed on the surface of disperse titanium dioxide was assessed using a combination of the differential concentration approach to the determination of adsorption and methods for determining the size of disperse adsorbents by dynamic light scattering and sedimentation analysis in the field of centrifugal forces. Three sections were found on the isotherm of adsorption: in the first, isolated islands of adsorbed macromolecules formed; in the second, layers of macromolecules with a different degree of deformation were observed; in the third, determining the adsorption of macromolecules is complicated by other accompanying processes, and assessing the state of macromolecules in the adsorption layer becomes difficult.

Dispersing and stabilizing effect of nonaqueous media with different acid-base functions when preparing process suspensions

International Nuclear Information System (INIS)

Koshevar, V.D.; Rat'ko, A.I.; Mironenko, I.N.

1999-01-01

Dispersing and stabilizing effect of organic liquids related to the Lewis acids and baser is studied when preparing the suspensions of certain minerals and metal oxides, beryllium oxide, in particular. Practical recommendations are provided for the choice of dispersing media to produce stable suspensions

Dissolution-modulating mechanism of pH modifiers in solid dispersion containing weakly acidic or basic drugs with poor water solubility.

Science.gov (United States)

Tran, Phuong Ha-Lien; Tran, Thao Truong-Dinh; Lee, Kyoung-Ho; Kim, Dong-Jin; Lee, Beom-Jin

2010-05-01

Although the solid dispersion method has been known to increase the dissolution rate of poorly water-soluble drugs by dispersing them in hydrophilic carriers, one obstacle of the solid dispersion method is its limited solubilization capacity, especially for pH-dependent soluble drugs. pH-modified solid dispersion, in which pH modifiers are incorporated, may be a useful method for increasing the dissolution rate of weakly acidic or basic drugs. Sufficient research, including the most recent reports, was undertaken in this review. How could the inclusion of the pH the pH modifiers in the solid dispersion system change drug structural behaviors, molecular interactions, microenvironmental pH, and/or release rate of pH modifiers, relating with the enhanced dissolution of weakly acidic or weakly basic drugs with poor water solubility? These questions have been investigated to determine the dissolution-modulating mechanism of pH modifiers in solid dispersion containing weakly acidic or basic drugs. It is believed that step-by-step mechanistic approaches could provide the ultimate solution for solubilizing several poorly water-soluble drugs with pH-dependent solubility from a solid dispersion system, as well as provide ideas for developing future dosage systems.

Enhanced dispersion of boron nitride nanosheets in aqueous media by using bile acid-based surfactants

Science.gov (United States)

Chae, Ari; Park, Soo-Jin; Min, Byunggak; In, Insik

2018-01-01

Facile noncovalent surface functionalization of hydroxylated boron nitride nanosheet (BNNS-OH) was attempted through the sonication-assisted exfoliation of h-BN in aqueous media in the presence of bile acid-based surfactants such as sodium cholic acid (SC) or sodium deoxycholic acid (SDC), resulting in SC- or SDC-BNNS-OH dispersion with high up to 2 mg ml-1 and enhanced dispersion stability due to the increased negative zeta potential. While prepared SC-BNNS-OH revealed multi-layered BNNS structures, the large lateral sizes of hundreds nanometers and clear h-BN lattice structures are very promising for the preparation and application of water-processable BNNS-based nanomaterials. It is regarded that noncovalent functionalization of BNNS-OH based on σ-π interaction between with σ-rich bile acid-based amphiphiles and π-rich BNNS is very effective to formulate multi-functional BNNS-based nanomaterials or hybrids that can be utilized in various applications where both the pristine properties of BNNS and the extra functions are simultaneously required.

Effects of Lignosulfonate Structure on the Surface Activity and Wettability to a Hydrophobic Powder

Directory of Open Access Journals (Sweden)

Yuanyuan Ge

2014-10-01

Full Text Available The wettability of a solid material is very important in many applications, such as food, agrochemical formulations, and cosmetics. Wettability can be improved by adding surface active agents, especially biocompatible surfactants derived from biomass. In this work, the surface activity (ability to lower the surface tension of an aqueous solution and wettability toward a hydrophobic powder by a series of sodium lignosulfonates (NaLS synthesized with different degree of sulfonation (QS and weight-average molecular weights (Mw were investigated by measuring the surface tension and contact angle. The results demonstrated NaLS with a larger Mw or lower QS had higher surface activity. Conversely, the wettability of the NaLS aqueous solution toward difenoconazole powder showed a reverse trend, i.e., NaLS with a smaller Mw or higher Qs improved the wettability to difenoconazole. The surface activity and wettability was controlled by the varying densities of the NaLS molecules at the water to air interface or the solid/liquid interface, which was dependent on the molecular structure of NaLS.

High titer ethanol and lignosulfonate production from SPORL pretreated poplar at pilot-scale

Directory of Open Access Journals (Sweden)

Junyong (J.Y. eZhu

2015-04-01

Full Text Available Poplar NE222 (Populus deltoides Bartr. ex Marsh × P. nigra L. wood chips were pretreated in a 390 L pilot-scale rotating wood-pulping digester using a dilute sulfite solution of approximately pH  1.8 at 160°C for 40 min for bioconversion to ethanol and lignosulfonate (LS. An estimated combined hydrolysis factor (CHF of 3.3 was used to scale the pretreatment temperature and time from laboratory bench scale experiments, which balanced sugar yield and inhibitor formation to facilitate high titer ethanol production through fermentation using S. cerevisiae YRH400 without detoxification. A terminal ethanol titer of 43.6 g L-1 with a yield of 247 L tonne wood-1 was achieved at total solids loading of 20%. The relatively low ethanol yield compared with yield from SPORL-pretreated softwoods was due to inefficient utilization of xylose. The LS from SPORL has a substantially higher phenolic group (Ph-OH content although it is less sulfonated and has a lower molecular weight than a purified commercial softwood LS, and therefore has potential for certain commercial markets and future novel applications through further processing.

Water-Dispersible Silica-Polyelectrolyte Nanocomposites Prepared via Acid-Triggered Polycondensation of Silicic Acid and Directed by Polycations

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Philip Overton

2016-03-01

Full Text Available The present work describes the acid-triggered condensation of silicic acid, Si(OH4, as directed by selected polycations in aqueous solution in the pH range of 6.5–8.0 at room temperature, without the use of additional solvents or surfactants. This process results in the formation of silica-polyelectrolyte (S-PE nanocomposites in the form of precipitate or water-dispersible particles. The mean hydrodynamic diameter (dh of size distributions of the prepared water-dispersible S-PE composites is presented as a function of the solution pH at which the composite formation was achieved. Poly(2-(dimethylaminoethyl methacrylate (PDMAEMA and block copolymers of DMAEMA and oligo(ethylene glycol methyl ether methacrylate (OEGMA were used as weak polyelectrolytes in S-PE composite formation. The activity of the strong polyelectrolytes poly(methacryloxyethyl trimethylammonium iodide (PMOTAI and PMOTAI-b-POEGMA in S-PE formation is also examined. The effect of polyelectrolyte strength and the OEGMA block on the formation of the S-PE composites is assessed with respect to the S-PE composites prepared using the PDMAEMA homopolymer. In the presence of the PDMAEMA60 homopolymer (Mw = 9400 g/mol, the size of the dispersible S-PE composites increases with solution pH in the range pH 6.6–8.1, from dh = 30 nm to dh = 800 nm. S-PDMAEMA60 prepared at pH 7.8 contained 66% silica by mass (TGA. The increase in dispersible S-PE particle size is diminished when directed by PDMAEMA300 (Mw = 47,000 g/mol, reaching a maximum of dh = 75 nm. S-PE composites formed using PDMAEMA-b-POEGMA remain in the range dh = 20–30 nm across this same pH regime. Precipitated S-PE composites were obtained as spheres of up to 200 nm in diameter (SEM and up to 65% mass content of silica (TGA. The conditions of pH for the preparation of dispersible and precipitate S-PE nanocomposites, as directed by the five selected polyelectrolytes PDMAEMA60, PDMAEMA300, PMOTAI60, PDMAEMA60-b-POEGMA38 and

Drilling mortar

Energy Technology Data Exchange (ETDEWEB)

Theodorescu, V; Ditulescu, E

1979-01-30

A method is proposed for producing stable drilling mortar from drilled rock which makes it possible to stabilize the walls of the borehole and to maintain producing horizons of oil and gas wells in an undisturbed state. The proposed drilling mortar includes 5-12 wt.-% dry modified calcium lignosulfonate in the form of a solution containing about 30% dry matter with the addition of 0.1 wt.-% anti-foaming agent consisting of C/sub 19/-C/sub 20/ alcohol dissolved in a light petroleum product; cream of milk with about 10 wt.-% Ca(OH)/sub 2/ in a quantity sufficient for reducing the pH value of the ions down to 10.5; sodium chloride in amounts from 5 mg to 100 ml (aqueous phase); ordinarily used agents for ensuring the necessary density, viscosity, and filterability. For example, the preparation of the drilling fluid begins with the processing under laboratory conditions of lignosulfonic pulp obtained in the production of yeast fodder with the following characteristics: specific density, 1.15 kgf/dm/sup 3/; water content, 67% (according to the Dean and Stark method); pH 4.0. In the vessel is placed 1000 cm/sup 3/ lignosulfonic pulp containing 33% dry matter, and the pulp is heated to 90-95/sup 0/C by means of a water bath. To the heated pulp 33 cm/sup 3/ formic acid at a 40-% concentration is added by mixing. The specific temperature of the pulp is maintained in the constant mixing process for two hours. Then the cream of milk containing 10 wt.-% Ca(OH)/sub 2/ is added to raise the pH to 10.5. The cooled product is calcium lignosulfonate. To produce a stable form of the drilling mortar, 750 g clay and 10 g trass gel are added to a vessel containing 1500 cm/sup 3/ fresh water by means of mixing. The resulting dispersed mass remains at rest for 12 hours for purposes of hydration. Then 2 g of an anti-foaming agent dissolved in 6 cm/sup 3/ benzene is introduced to 1000 cm/sup 3/ modified calcium lignosulfonate produced by the above method.

Thermoelectric properties of electrodeposited tellurium films and the sodium lignosulfonate effect

International Nuclear Information System (INIS)

Abad, Begoña; Rull-Bravo, Marta; Hodson, Stephen L.; Xu, Xianfan; Martin-Gonzalez, Marisol

2015-01-01

The effect of the addition of a surfactant, sodium lignosulfonate (SLS), on the thermoelectric properties of tellurium films prepared by electrochemical deposition is studied. The growth mechanism is found to have an important role in the thermoelectric properties since the grain size of the films is sharply reduced when the surfactant is added to the solution. For this reason, the electrical resistivity of the tellurium films when the surfactant is not added is 229 μΩ·m, which is lower than 798 μΩ·m with SLS. The Seebeck coefficient values are not influenced, with values in the vicinity of 285 μV/K for both solutions. The power factor resulted higher values than previous works, reaching values of 280 μW/m·K 2 (without SLS) and 82 μW/m·K 2 (with SLS) at room temperature. Finally, the thermal conductivity was measured by means of the Photoacoustic technique, which showed values of the order of 1 W/m·K for both solutions, which is a factor of 3 less than the bulk value of tellurium. A notable observation is that the power factor and the thermal conductivity of electrodeposited tellurium films have the same order of magnitude of bismuth telluride films grown by electrodeposition. The figure of merit is estimated to be approximately one order of magnitude higher than the bulk value, 0.09 without SLS and 0.03 with SLS, both at room temperature

Synthesis of water dispersible polyaniline/poly(styrenesulfonic acid) modified graphene composite and its electrochemical properties

International Nuclear Information System (INIS)

Luo, Jing; Jiang, Sisi; Liu, Ren; Zhang, Yongjie; Liu, Xiaoya

2013-01-01

A novel water-dispersible polyaniline (PANI)/graphene composite was prepared by the in situ polymerization of aniline on the surface of poly(styrenesulfonic acid) (PSS) coated graphene nanosheets (PSS-GR). The characterization of atomic force microscopy (AFM), transmission electron microscopy (TEM), Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy confirmed the successful synthesis of PANI/PSS-GR composites and strong interaction between PANI and PSS-GR. The as-synthesized PANI/PSS-GR composite is readily dispersible in water and forms a homogeneous aqueous dispersion which is stable for more than one month. More interestingly, PSS-GR can dope PANI effectively and shift its electroactivity to a neutral or even alkaline environment, making them promising candidates for biological application. In addition, the PANI/PSS-GR composite shows improved electrical conductivity and electrochemical stability compared to the neat polyaniline. Furthermore, the potential use of this composite for detection of ascorbic acid (AA) was investigated. A low detection limit of 5 × 10 −6 M and a linear detection range between 1 × 10 −4 M and 1 × 10 −3 M was attained, indicating the high electrocatalytic ability of this composite. Anticipatedly, the synthesized composite will find promising applications as a novel electrode material in sensors and other devices in virtue of their outstanding characteristics of water-dispersibility, good cycle stability, electroactivity in neutral solution and excellent electrocatalytic ability

Structural diversity of solid dispersions of acetylsalicylic acid as seen by solid-state NMR

Czech Academy of Sciences Publication Activity Database

Policianová, Olivia; Brus, Jiří; Hrubý, Martin; Urbanová, Martina; Zhigunov, Alexander; Kredatusová, Jana; Kobera, Libor

2014-01-01

Roč. 11, č. 2 (2014), s. 516-530 ISSN 1543-8384 R&D Projects: GA ČR GPP106/11/P426 Institutional support: RVO:61389013 Keywords : solid dispersions * acetylsalicylic acid * polymers Subject RIV: FR - Pharmacology ; Medidal Chemistry Impact factor: 4.384, year: 2014

Sulfur-free lignins from alkaline pulping tested in mortar for use as mortar additives.

Science.gov (United States)

Nadif, A; Hunkeler, D; Käuper, P

2002-08-01

Sulfur-free lignin, obtained through the acid precipitation of black liquor from the soda pulping process, has been tested as water reducer in mortar. It has also been compared to existing commercial additives such as naphthalene sulfonates and lignosulfonates. The ash content and sugar content of these lignins are low in comparison to lignosulfonates, conferring on them higher purity. A procedure for small scale testing derived from the industrial norms SN-EN196 and ASTM (Designation C230-90) is presented. Specifically, all the sulfur-free lignins tested improved the flow of the mortar. Selected flax lignins performed better than lignosulfonates though still less than naphthalene sulfonates. Furthermore, certain hemp lignins gave comparable results to the lignosulfonates. Overall, the straw lignin prepared herein is comparable in performance to commercially available lignins, such as Organocell, Alcell and Curan 100. The plant from which the lignin was isolated, and the process of the pulp mill are the primary influences on the performance of the lignin.

Alginic Acid-Aided Dispersion of Carbon Nanotubes, Graphene, and Boron Nitride Nanomaterials for Microbial Toxicity Testing.

Science.gov (United States)

Wang, Ying; Mortimer, Monika; Chang, Chong Hyun; Holden, Patricia A

2018-01-30

Robust evaluation of potential environmental and health risks of carbonaceous and boron nitride nanomaterials (NMs) is imperative. However, significant agglomeration of pristine carbonaceous and boron nitride NMs due to strong van der Waals forces renders them not suitable for direct toxicity testing in aqueous media. Here, the natural polysaccharide alginic acid (AA) was used as a nontoxic, environmentally relevant dispersant with defined composition to disperse seven types of carbonaceous and boron nitride NMs, including multiwall carbon nanotubes, graphene, boron nitride nanotubes, and hexagonal boron nitride flakes, with various physicochemical characteristics. AA's biocompatibility was confirmed by examining AA effects on viability and growth of two model microorganisms (the protozoan Tetrahymena thermophila and the bacterium Pseudomonas aeruginosa ). Using 400 mg·L -1 AA, comparably stable NM (200 mg·L -1 ) stock dispersions were obtained by 30-min probe ultrasonication. AA non-covalently interacted with NM surfaces and improved the dispersibility of NMs in water. The dispersion stability varied with NM morphology and size rather than chemistry. The optimized dispersion protocol established here can facilitate preparing homogeneous NM dispersions for reliable exposures during microbial toxicity testing, contributing to improved reproducibility of toxicity results.

Alginic Acid-Aided Dispersion of Carbon Nanotubes, Graphene, and Boron Nitride Nanomaterials for Microbial Toxicity Testing

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Ying Wang

2018-01-01

Full Text Available Robust evaluation of potential environmental and health risks of carbonaceous and boron nitride nanomaterials (NMs is imperative. However, significant agglomeration of pristine carbonaceous and boron nitride NMs due to strong van der Waals forces renders them not suitable for direct toxicity testing in aqueous media. Here, the natural polysaccharide alginic acid (AA was used as a nontoxic, environmentally relevant dispersant with defined composition to disperse seven types of carbonaceous and boron nitride NMs, including multiwall carbon nanotubes, graphene, boron nitride nanotubes, and hexagonal boron nitride flakes, with various physicochemical characteristics. AA’s biocompatibility was confirmed by examining AA effects on viability and growth of two model microorganisms (the protozoan Tetrahymena thermophila and the bacterium Pseudomonas aeruginosa. Using 400 mg·L−1 AA, comparably stable NM (200 mg·L−1 stock dispersions were obtained by 30-min probe ultrasonication. AA non-covalently interacted with NM surfaces and improved the dispersibility of NMs in water. The dispersion stability varied with NM morphology and size rather than chemistry. The optimized dispersion protocol established here can facilitate preparing homogeneous NM dispersions for reliable exposures during microbial toxicity testing, contributing to improved reproducibility of toxicity results.

Synthesis and characterization of sulfonate polystyrene-lignosulfonate-alumina (SPS-LS-Al{sub 2}O{sub 3}) polyblends as electrolyte membranes for fuel cell

Energy Technology Data Exchange (ETDEWEB)

Gonggo, Siang Tandi, E-mail: standigonggo@yahoo.com [Chemistry Research Groups, Faculty of Teacher Training and Educational Sciences, Tadulako University (Indonesia)

2015-09-30

The new type of electrolyte membrane materials has been prepared by blend sulfonated polystyrene (SPS), lignosulfonate (LS), and alumina (SPS-LS-Al{sub 2}O{sub 3}) by casting polymer solution. The resulting polymer electrolyte membranes were then characterized by functional groups analysis, mechanical properties, water uptake, ion exchange capacity, and proton conductivity. SPS-LS-Al{sub 2}O{sub 3} membranes with alumina composition various have been proven qualitatively by analysis of functional groups. Increasing the Al{sub 2}O{sub 3} ratio resulted in higher ion exchange capacity (IEC), mechanical strength and proton conductivity, but water uptake decreased. The SPS-LS-Al{sub 2}O{sub 3} blend showed higher proton conductivity than Nafion 117.

High Titer Ethanol and Lignosulfonate Production from SPORL Pretreated Poplar at Pilot Scale

Energy Technology Data Exchange (ETDEWEB)

Zhou, Haifeng [Key Laboratory of Low Carbon Energy and Chemical Engineering, Shandong University of Science and Technology, Qingdao (China); Forest Products Laboratory, USDA Forest Service, Madison, WI (United States); Zhu, J. Y., E-mail: jzhu@fs.fed.us; Gleisner, Roland [Forest Products Laboratory, USDA Forest Service, Madison, WI (United States); Qiu, Xueqing [School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou (China); Horn, Eric [BioPulping International, Inc., Madison, WI (United States)

2015-04-27

Poplar NE222 (Populus deltoides Bartr. ex Marsh × P. nigra L.) wood chips were pretreated in a 390 L pilot-scale rotating wood-pulping digester using a dilute sulfite solution of approximately pH 1.8 at 160°C for 40 min for bioconversion to ethanol and lignosulfonate (LS). An estimated combined hydrolysis factor (CHF) of 3.3 was used to scale the sulfite pretreatment temperature and time from laboratory bench scale experiments, which balanced sugar yield and inhibitor formation to facilitate high titer ethanol production through fermentation using S. cerevisiae YRH400 without detoxification. A terminal ethanol titer of 43.6 g L{sup -1} with a yield of 247 L tonne wood{sup -1} was achieved at total solids loading of 20%. The relatively low ethanol yield compared with yield from Sulfite pretreatment to overcome the recalcitrance of lignocelluloses (SPORL)-pretreated softwoods was due to inefficient utilization of xylose. The LS from SPORL has a substantially higher phenolic group (Ph-OH) content, though it was less sulfonated and had a lower molecular weight than a purified commercial softwood LS, and therefore has potential for certain commercial markets and future novel applications through further processing. The conversion efficiency achieved through process integration and simplification, demonstrated here, has significant importance to the entire supply chain of biofuel production from woody biomass.

Highly water-dispersible, mixed ionic-electronic conducting, polymer acid-doped polyanilines as ionomers for direct methanol fuel cells.

Science.gov (United States)

Murthy, Arun; Manthiram, Arumugam

2011-06-28

Highly water-dispersible polymer acid-doped polyanilines have been synthesized and evaluated as an alternative for expensive Nafion ionomers in the anode of direct methanol fuel cells (DMFC). These polymers as ionomers lead to higher performance in single cell DMFC compared to Nafion ionomers due to mixed ionic-electronic conduction, water dispersibility, and co-catalytic activity. This journal is © The Royal Society of Chemistry 2011

The role of poly(methacrylic acid) conformation on dispersion behavior of nano TiO2 powder

Science.gov (United States)

Singh, Bimal P.; Nayak, Sasmita; Samal, Samata; Bhattacharjee, Sarama; Besra, Laxmidhar

2012-02-01

To exploit the advantages of nanoparticles for various applications, controlling the dispersion and agglomeration is of paramount importance. Agglomeration and dispersion behavior of titanium dioxide (TiO2) nanoparticles was investigated using electrokinetic and surface chemical properties. Nanoparticles are generally stabilized by the adsorption of a dispersant (polyelectrolyte) layer around the particle surface and in this connection ammonium salt of polymethacrylic acid (Darvan C) was used as dispersant to stabilize the suspension. The dosages of polyelectrolyte were optimized to get best dispersion stability by techniques namely particle charge detector (13.75 mg/g) and adsorption (14.57 mg/g). The surface charge of TiO2 particles changed significantly in presence of dispersant Darvan C and isoelectric point (iep) shifted significantly towards lower pH from 5.99 to 3.37. The shift in iep has been quantified in terms of free energy of interaction between the surface sites of TiO2 and the adsorbing dispersant Darvan C. Free energies of adsorption were calculated by electrokinetic data (-9.8 RT unit) and adsorption isotherms (-10.56 RT unit), which corroborated well. The adsorption isotherms are of typical Langmuir type and employed for calculation of free energy. The results indicated that adsorption occurs mainly through electrostatic interactions between the dispersant molecule and the TiO2 surface apart from hydrophobic interactions.

Structural diversity of solid dispersions of acetylsalicylic acid as seen by solid-state NMR.

Science.gov (United States)

Policianova, Olivia; Brus, Jiri; Hruby, Martin; Urbanova, Martina; Zhigunov, Alexander; Kredatusova, Jana; Kobera, Libor

2014-02-03

Solid dispersions of active pharmaceutical ingredients are of increasing interest due to their versatile use. In the present study polyvinylpyrrolidone (PVP), poly[N-(2-hydroxypropyl)-metacrylamide] (pHPMA), poly(2-ethyl-2-oxazoline) (PEOx), and polyethylene glycol (PEG), each in three Mw, were used to demonstrate structural diversity of solid dispersions. Acetylsalicylic acid (ASA) was used as a model drug. Four distinct types of the solid dispersions of ASA were created using a freeze-drying method: (i) crystalline solid dispersions containing nanocrystalline ASA in a crystalline PEG matrix; (ii) amorphous glass suspensions with large ASA crystallites embedded in amorphous pHPMA; (iii) solid solutions with molecularly dispersed ASA in rigid amorphous PVP; and (iv) nanoheterogeneous solid solutions/suspensions containing nanosized ASA clusters dispersed in a semiflexible matrix of PEOx. The obtained structural data confirmed that the type of solid dispersion can be primarily controlled by the chemical constitutions of the applied polymers, while the molecular weight of the polymers had no detectable impact. The molecular structure of the prepared dispersions was characterized using solid-state NMR, wide-angle X-ray scattering (WAXS), and differential scanning calorimetry (DSC). By applying various (1)H-(13)C and (1)H-(1)H correlation experiments combined with T1((1)H) and T1ρ((1)H) relaxation data, the extent of the molecular mixing was determined over a wide range of distances, from intimate intermolecular contacts (0.1-0.5 nm) up to the phase-separated nanodomains reaching ca. 500 nm. Hydrogen-bond interactions between ASA and polymers were probed by the analysis of (13)C and (15)N CP/MAS NMR spectra combined with the measurements of (1)H-(15)N dipolar profiles. Overall potentialities and limitations of individual experimental techniques were thoroughly evaluated.

Preparation of Multiwalled Carbon Nanotube-Poly (4-Styrenesulfonic Acid Aqueous Dispersion for Dopamine Sensing

Directory of Open Access Journals (Sweden)

Aihua LIU

2006-12-01

Full Text Available A simple and facile method for the non-covalent functionalization of multi-walled carbon nanotubes (MWNTs using poly(4-styrenesulfonic acid (PSS is proposed. The resulting PSS-MWNTs dispersion is readily soluble in water and can be left to stand for 2 weeks at room temperature, no phase separation with aggregation of nanotubes at the bottom of the vials was observed. The as-prepared PSS-MWNTs dispersions could facilitate the processing of the nanotubes into composites with high nanotube loading. The PSS-MWNTs complex shows high electrocatalytic activity to the oxidation of neutrontransmitter of dopamine, suggesting that the coating of PSS onto carbon nanotubes surface without destroying the electronic structures of the pristine carbon nanotubes; therefore, the unique properties including the catalytic property of the nanotubes retained. It is envisioned that the PSS-MWNTs aqueous dispersions may find possible applications in the development of biosensors, bioelectronics, separation and environment protection as well as other biological events where water-based environment is required.

Dispersion Process and Effect of Oleic Acid on Properties of Cellulose Sulfate- Oleic Acid Composite Film

Science.gov (United States)

Chen, Guo; Zhang, Bin; Zhao, Jun

2015-01-01

The cellulose sulfate (CS) is a newly developed cellulose derivative. The work aimed to investigate the effect of oleic acid (OA) content on properties of CS-OA film. The process of oleic acid dispersion into film was described to evaluate its effect on the properties of the film. Among the formulations evaluated, the OA addition decreased the solubility and water vapor permeability of the CS-OA film. The surface contact angle changed from 64.2° to 94.0° by increasing CS/OA ratio from 1:0 to 1:0.25 (w/w). The TS increased with OA content below 15% and decreased with OA over 15%, but the ε decreased with higher OA content. The micro-cracking matrices and micro pores in the film indicated the condense structure of the film destroyed by the incorporation of oleic acid. No chemical interaction between the OA and CS was observed in the XRD and FTIR spectrum. Film formulation containing 2% (w/w) CS, 0.3% (w/w) glycerol and 0.3% (w/w) OA, showed good properties of mechanic, barrier to moisture and homogeneity.

Lysophosphatidic Acid Upregulates Laminin-332 Expression during A431 Cell Colony Dispersal

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Hironobu Yamashita

2010-01-01

Full Text Available Lysophosphatidic acid (LPA is a bioactive phospholipid that affects various biological functions, such as cell proliferation, migration, survival, wound healing, and tumor invasion through LPA receptors. Previously, we reported that LPA induces A431 colony dispersal, accompanied by disruption of cell-cell contacts and cell migration. However, it remains unclear how LPA affects cell migration and gene expression during A431 colony dispersal. In this paper, we performed cDNA microarray analysis to investigate this question by comparing gene expression between untreated and LPA-treated A431 cells. Interestingly, these results revealed that LPA treatment upregulates several TGF-β1 target genes, including laminin-332 (Ln-332 components (α3, β3, and γ2 chains. Western blot analysis also showed that LPA increased phosphorylation of Smad2, an event that is carried out by TGF-β1 interactions. Among the genes upregulated, we further addressed the role of Ln-332. Real-time PCR analysis confirmed the transcriptional upregulation of all α3, β3, and γ2 chains of Ln-332 by LPA, corresponding to the protein level increases revealed by western blot. Further, the addition of anti-Ln-332 antibody prevented LPA-treated A431 colonies from dispersing. Taken together, our results suggest that LPA-induced Ln-332 plays a significant role in migration of individual cells from A431 colonies.

BisGMA/TEGDMA dental nanocomposites containing glyoxylic acid modified high-aspect ratio hydroxyapatite nanofibers with enhanced dispersion

Science.gov (United States)

Chen, Liang; Xu, Changqi; Wang, Yong; Shi, Jian; Yu, Qingsong

2012-01-01

The purpose of this research was to investigate the influence of the glyoxylic acid (GA) modification of hydroxyapatite (HAP) nanofibers on their dispersion in bisphenol A glycidyl methacrylate (BisGMA)/triethylene glycol dimethacrylate (TEGDMA) dental composites and also investigate the mechanical properties, water absorption, and water solubility of the resulting dental resins and composites. Scanning/Transmission electron microscopy (STEM) images showed that microsized HAP nanofiber bundles could be effectively broken down to individual HAP nanofibers with an average length of ~15 μm after the surface modification process. Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and thermal gravimetric analysis (TGA) characterization confirmed glyoxylic acid was chemically grafted on the HAP nanofiber surface, hypothetically by reacting with the amine group on HAP nanofiber surface. The enhanced dispersion of HAP nanofibers in dental matrix led to increased biaxial flexural strength (BFS) compared with the corresponding dental resins and composites filled with untreated HAP nanofibers. In addition, impregnation of small mass fractions of the glyoxylic acid modified HAP nanofibers into the BisGMA/TEGDMA dental resins (5wt%, 10wt%) or composites (2wt%, 3wt%) could also substantially improve the BFS in comparison with the controls(pure resins or dental composites filled with silica particles alone). Larger mass fractions could not further increase the mechanical property or even degrade the BFS values. Water behavior testing results indicated that the addition of glyoxylic acid modified HAP nanofibers resulted in higher water absorption and water solubility values which is not preferred for clinical application. In summary, well dispersed HAP nanofibers and their dental composites with enhanced mechanical property have been successfully fabricated but the water absorption and water solubility of such dental composites need to be

Self-assembly of caseinomacropeptide as a potential key mechanism in the formation of visible storage induced aggregates in acidic whey protein isolate dispersions

DEFF Research Database (Denmark)

Villumsen, Nanna Stengaard; Jensen, Hanne Bak; Thu Le, Thao Thi

2015-01-01

Visible aggregates formed during storage in acidic whey protein isolate (WPI) dispersions represent a challenge to the beverage industry. Batch-to-batch variations are observed that prevents consistent quality and shelf-life prediction. Heat-treatment of WPI dispersions at 120°C for 20s instead...

Lignonsulfonate-phenolformaldehyrde adhesive: a potential binder for wood panel industries

International Nuclear Information System (INIS)

Akhtar, T.; Lutfullah, G.; Ullah, Z.

2011-01-01

Spent sulfite liquor (SSL) was obtained from a paper mill based on grassy pulp material (bagasse, kaigrass and wheat straws). Lignosulfonate (LS) was isolated from SSL by polymerization reaction, initiated with concentrated hydrochloric acid. Different adhesives were prepared by gradual replacement of phenol by LS in phenol-formaldehyde (PF) resole resin. The strength of these resins was evaluated by glue block shear test in two wood species, in both dry and wet states. Maximum shear strength and wood failure was obtained by 20% addition of lignosulfonate to PF resin. No significant difference was observed in shear strength and wood failure of the two wood species in dry and wet states indicating that the resin obtained is waterproof. The results obtained from this study were compared with different commercial glues. Our results were found better than these glues event at a ratio 50: 50 of PF to lignosulfonate. (author)

Application of acid-catalyzed hydrolysis of dispersed organic solvent in developing new microencapsulation process technology.

Science.gov (United States)

Lee, Honghwa; Lee, Sunhwa; Bhattacharjee, Himanshu; Sah, Hongkee

2012-01-01

The aim of this study was to evaluate a new microencapsulation technology employing an acid-catalyzed solvent extraction method in conjunction to an emulsion-based microencapsulation process. Its process consisted of emulsifying a dispersed phase of poly(D,L-lactide-co-glycolide) and isopropyl formate in an aqueous phase. This step was followed by adding hydrochloric acid to the resulting oil-in-water emulsion, in order to initiate the hydrolysis of isopropyl formate dissolved in the aqueous phase. Its hydrolysis caused the liberation of water-soluble species, that is, isopropanol and formic acid. This event triggered continual solvent leaching out of emulsion droplets, thereby initiating microsphere solidification. This new processing worked well for encapsulation of progesterone and ketoprofen that were chosen as a nonionizable model drug and a weakly acidic one, respectively. Furthermore, the structural integrity of poly(D,L-lactide-co-glycolide) was retained during microencapsulation. The new microencapsulation technology, being conceptually different from previous approaches, might be useful in preparing various polymeric particles.

21 CFR 173.310 - Boiler water additives.

Science.gov (United States)

2010-04-01

...-sodium acrylate resin Contains not more than 0.05 percent by weight of acrylamide monomer. Acrylic acid/2...-hydroxyethylidene-1,1-diphosphonic acid (CAS Reg. No. 2809-21-4) and its sodium and potassium salts Lignosulfonic.... Potassium carbonate Potassium tripolyphosphate Sodium acetate Sodium alginate Sodium aluminate Sodium...

Influence of expander components on the processes at the negative plates of lead-acid cells on high-rate partial-state-of-charge cycling. Part II. Effect of carbon additives on the processes of charge and discharge of negative plates

Energy Technology Data Exchange (ETDEWEB)

Pavlov, D.; Nikolov, P.; Rogachev, T. [Institute of Electrochemistry and Energy Systems, Bulgarian Academy of Sciences, Acad. Georgi Bonchev Street, bl. 10, Sofia 1113 (Bulgaria)

2010-07-15

Lead-acid batteries operated in the high-rate partial-state-of-charge (HRPSoC) duty rapidly lose capacity on cycling, because of sulfation of the negative plates. As the battery operates from a partially discharged state, the small PbSO{sub 4} crystals dissolve and precipitate onto the bigger crystals. The latter have low solubility and hence PbSO{sub 4} accumulates progressively in the negative plates causing capacity loss. In order to suppress this process, the rate of the charge process should be increased. In a previous publication of ours we have established that reduction of Pb{sup 2+} ions to Pb may proceed on the surface of both Pb and carbon black particles. Hence, the reversibility of the charge-discharge processes improves, which leads to improved cycle life performance of the batteries in the HRPSoC mode. However, not all carbon forms accelerate the charge processes. The present paper discusses the electrochemical properties of two groups of carbon blacks: Printex and active carbons. The influence of Vaniseprse A and BaSO{sub 4} (the other two components of the expander added to the negative plates) on the reversibility of the charge-discharge processes on the negative plates is also considered. It has been established that lignosulfonates are adsorbed onto the lead surface and retard charging of the battery. BaSO{sub 4} has the opposite effect, which improves the reversibility of the processes on cycling and hence prolongs battery life in the HRPSoC duty. It has been established that the cycle life of lead-acid cells depends on the type of carbon black or active carbon added to the negative plates. When the carbon particles are of nano-sizes (<180 nm), the HRPSoC cycle life is between 10,000 and 20,000 cycles. Lignosulfonates suppress this beneficial effect of carbon black and activated carbon additives to about 10,000 cycles. Cells with active carbons have the longest cycle life when they contain also BaSO{sub 4} but no lignosulfonate. A summary of

Procedure for preparation of dispersions

International Nuclear Information System (INIS)

1978-01-01

Procedure for the preparation of a water based dispersion of cerium oxide, characterised in that a suspension of cerium (IV) hydroxide is formed with an acid, where the acid is in the state of a disaggregation of aggregated crystalline cerium hydroxide, the suspension being preheated for a specified time and to a specified temperature, so that the pH value becomes constant, and whereby the quantity of acid in the suspension is such that the constant pH value is lower than 5.4, so that a conditioned suspension may be obtained, and water may be mixed with the conditioned suspension for making a water based dispersion of cerium oxide. (G.C.)

Improvements in or relating to dispersions

International Nuclear Information System (INIS)

Woodhead, J.L.

1981-01-01

A process is described for the preparation of an aqueous dispersion of ceria which comprises forming a slurry of cerium IV hydroxide with water and an acid, the acid being capable of causing deaggregation of aggregated crystallites in the cerium IV hydroxide, heating the slurry for such a time and at such a temperature that the pH reaches a steady value, the quantity of acid in the slurry being such that the steady value of pH is below 5.4, thereby to produce a conditioned slurry, and admixing water with the conditioned slurry to produce an aqueous dispersion of ceria. (author)

Translational and rotational diffusion of flexible PEG and rigid dendrimer probes in sodium caseinate dispersions and acid gels

NARCIS (Netherlands)

Salami, S.; Rondeau-Mouro, C.; Barhoum, M.; Duynhoven, van J.P.M.; Mariette, F.

2014-01-01

The dynamics of rigid dendrimer and flexible PEG probes in sodium caseinate dispersions and acid gels, including both translational diffusion and rotational diffusion, were studied by NMR. Above the onset of the close-packing limit (C ~ 10 g/100 g H2O), translational diffusion of the probe depended

Determination of haloacetic acids in water using layered double hydroxides as a sorbent in dispersive solid-phase extraction followed by liquid chromatography with tandem mass spectrometry.

Science.gov (United States)

Alsharaa, Abdulnaser; Sajid, Muhammad; Basheer, Chanbasha; Alhooshani, Khalid; Lee, Hian Kee

2016-09-01

In the present study, highly efficient and simple dispersive solid-phase extraction procedure for the determination of haloacetic acids in water samples has been established. Three different types of layered double hydroxides were synthesized and used as a sorbent in dispersive solid-phase extraction. Due to the interesting behavior of layered double hydroxides in an acidic medium (pH˂4), the analyte elution step was not needed; the layered double hydroxides are simply dissolved in acid immediately after extraction to release the analytes which are then directly introduced into a liquid chromatography with tandem mass spectrometry system for analysis. Several dispersive solid-phase extraction parameters were optimized to increase the extraction efficiency of haloacetic acids such as temperature, extraction time and pH. Under optimum conditions, good linearity was achieved over the concentration range of 0.05-100 μg/L with detection limits in the range of 0.006-0.05 μg/L. The relative standard deviations were 0.33-3.64% (n = 6). The proposed method was applied to different water samples collected from a drinking water plant to determine the concentrations of haloacetic acids. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Uranium dispersion in the coating of weak-acid-resin-deprived HTGR fuel microspheres

International Nuclear Information System (INIS)

Weber, G.W.; Beatty, R.L.; Tennery, V.J.; Lackey, W.J. Jr.

1976-02-01

The current reference HTGR recycle fuel particle is a UO 2 /UC 2 kernel with a Triso coating comprising a low-density pyrocarbon (PyC) buffer, a high-density PyC inner LTI coating, SiC, and a high-density PyC outer LTI. The kernel is fabricated from a weak-acid ion exchange resin (WAR). Microradiographic examination of coated WAR particles has demonstrated that considerable U can be transferred from the kernel to the buffer coating during fabrication. Investigation of causes of fuel dispersion has indicated several different factors that contribute to fuel redistribution if not properly controlled. The presence of a nonequilibrium UC/sub 1-x/O/sub x/ (0 less than or equal to x less than or equal to 0.3) phase had no significant effect on initiating fuel dispersion. Gross exposure of the completed fuel kernel to ambient atmosphere or to water vapor at room temperature produced very minimal levels of dispersion. Exposure of the fuel to perchloroethylene during buffer and inner LTI deposition produced massive redistribution. Fuel redistribution observed in Triso-coated particles results from permeation of the inner LTI by HCl during SiC deposition. As the decomposition of CH 3 Cl 3 Si is used to deposit SiC, chlorine is readily available during this process. The permeability of the inner LTI coating has a marked effect on the extent of this mode of fuel dispersion. LTI permeability was determined by chlorine leaching studies to be a strong function of density, coating gas dilution, and coating temperature but relatively unaffected by application of a seal coat, variations in coating thickness, and annealing at 1800 0 C. Mechanical attrition of the kernels during processing was identified as a potential source of U-bearing fines that may be incorporated into the coating in some circumstances

Use of Fatty Acid Analysis to Determine Dispersal of Caspian Terns in the Columbia River Basin, U.S.A.

Science.gov (United States)

Maranto, C.J.; Parrish, J.K.; Herman, D.P.; Punt, A.E.; Olden, J.D.; Brett, M.T.; Roby, D.D.

2011-01-01

Lethal control, which has been used to reduce local abundances of animals in conflict with humans or with endangered species, may not achieve management goals if animal movement is not considered. In populations with emigration and immigration, lethal control may induce compensatory immigration, if the source of attraction remains unchanged. Within the Columbia River Basin (Washington, U.S.A.), avian predators forage at dams because dams tend to reduce rates of emigration of juvenile salmonids (Oncorhynchus spp.), artificially concentrating these prey. We used differences in fatty acid profiles between Caspian Terns (Hydroprogne caspia) at coastal and inland breeding colonies and terns culled by a lethal control program at a mid-Columbia River dam to infer dispersal patterns. We modeled the rate of loss of fatty acid biomarkers, which are fatty acids that can be traced to a single prey species or groups of species, to infer whether and when terns foraging at dams had emigrated from the coast. Nonmetric multidimensional scaling showed that coastal terns had high levels of C20 and C22 monounsaturated fatty acids, whereas fatty acids of inland breeders were high in C18:3n3, C20:4n6, and C22:5n3. Models of the rate of loss of fatty acid showed that approximately 60% of the terns collected at Rock Island Dam were unlikely to have bred successfully at local (inland) sites, suggesting that terns foraging at dams come from an extensive area. Fatty acid biomarkers may provide accurate information about patterns of dispersal in animal populations and may be extremely valuable in cases where populations differ demonstrably in prey base. ??2011 Society for Conservation Biology.

Debundling of single-walled carbon nanotubes by using natural polyelectrolytes

International Nuclear Information System (INIS)

Liu Yangqiao; Gao Lian; Zheng Shan; Wang Yan; Sun Jing; Kajiura, Hisashi; Li Yongming; Noda, Kazuhiro

2007-01-01

Natural polyelectrolytes (NPs), including sodium lignosulfonate, humic acid and so forth, are reported for the first time to solubilize single-walled carbon nanotubes (SWNTs) in water through a noncovalent interaction. A variety of methods, including transmission electron microscopy (TEM), visible-near-infrared (vis-NIR) spectra, Raman spectra and zeta potential measurements, were used to characterize the NP-dispersed SWNT solutions. It is found that the SWNTs can be exfoliated into thin bundles or individual tubes, even at NP concentrations as low as 0.15 mg ml -1 . Their high performance is attributed to the abundance of aromatic groups and ionized groups in the NP molecules. This method of solubilization opens the way for exploiting new natural materials as SWNT solubilizers and may find applications in nanocomposites, self-assembly, and so forth

Debundling of single-walled carbon nanotubes by using natural polyelectrolytes

Energy Technology Data Exchange (ETDEWEB)

Liu Yangqiao [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Gao Lian [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Zheng Shan [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Wang Yan [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Sun Jing [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Kajiura, Hisashi [Materials Laboratories, Sony Corporation, Atsugi Tec. No. 2, 4-16-1 Okata Atsugi, Kanagawa 243-0021 (Japan); Li Yongming [Materials Laboratories, Sony Corporation, Atsugi Tec. No. 2, 4-16-1 Okata Atsugi, Kanagawa 243-0021 (Japan); Noda, Kazuhiro [Materials Laboratories, Sony Corporation, Atsugi Tec. No. 2, 4-16-1 Okata Atsugi, Kanagawa 243-0021 (Japan)

2007-09-12

Natural polyelectrolytes (NPs), including sodium lignosulfonate, humic acid and so forth, are reported for the first time to solubilize single-walled carbon nanotubes (SWNTs) in water through a noncovalent interaction. A variety of methods, including transmission electron microscopy (TEM), visible-near-infrared (vis-NIR) spectra, Raman spectra and zeta potential measurements, were used to characterize the NP-dispersed SWNT solutions. It is found that the SWNTs can be exfoliated into thin bundles or individual tubes, even at NP concentrations as low as 0.15 mg ml{sup -1}. Their high performance is attributed to the abundance of aromatic groups and ionized groups in the NP molecules. This method of solubilization opens the way for exploiting new natural materials as SWNT solubilizers and may find applications in nanocomposites, self-assembly, and so forth.

Effects of humic acid and solution chemistry on the aggregation and dispersion of carboxyl-functionalized carbon black nanoparticles

Science.gov (United States)

Hwang, G.; Gomez-Flores, A.; Choi, S.; Han, Y., , Dr; Kim, H.

2017-12-01

The influence of humic acid, ionic strength and ionic species on the aggregation and dispersion of carboxyl-functionalized carbon black nanoparticles (CB-NPs) was systemically investigated in aqueous media. The experimental conditions of stability tests were selected to the changes in the solution chemistry (0.1-10 mM NaCl and 0.01-1 mM CaCl2) and in the presence/absence of humic acid (1 and 5 mg L-1) in an aquatic environment. The CB-NPs suspension was more rapidly settled in NaCl solution than in CaCl2. Specifically, in the case of NaCl, the aggregation rate of CB-NPs increased with ionic strength. Contrary, CB-NPs dispersed in CaCl2 were insensitive to the aggregation as the ionic strength increased; that was because specific adsorption of the divalent cation Ca2+ occurred since the zeta potential of the CB-NPs is reversed to a positive charge with increasing of the ionic strength. It was confirmed that humic acid greatly influences the stability of the CB-NPs. In particular, the dispersion of CB-NPs was improved in the whole range of ionic strengths of NaCl as well as of CaCl2. To support the results, the interaction energy between CB-NPs was calculated for each condition by using the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) and modified-DLVO theories. In the presence of humic acid, the improved stability of CB-NPs is attributed to the steric repulsive force.This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2015R1D1A3A01020766), the Ministry of Education (MOE) and National Research Foundation of Korea (NRF) through the Human Resource Training Project for Regional Innovation (2015H1C1A1035930) and Korea Energy and Mineral Resources Engineering Program (KEMREP).

Ferrofluid synthesis using oleic acid coated Fe3O4 nanoparticles dispersed in mineral oil for heat transfer applications

Science.gov (United States)

Imran, Mohd; Rahman Ansari, Akhalakur; Hussain Shaik, Aabid; Abdulaziz; Hussain, Shahir; Khan, Afzal; Rehaan Chandan, Mohammed

2018-03-01

Ferrofluids are stable dispersion of iron oxide nanoparticles in a carrier fluid which find potential applications in heat transfer. Fe3O4 nanoparticles of mean size in the range of 5–10 nm were synthesized using conventional co-precipitation method. This work deals with the synthesis of ferrofluids using mineral oil as a carrier fluid and oleic acid coated Fe3O4 nanoparticles as dispersed phase. Morphology (shape and size) and crystallinity of the synthesized nanoparticle is captured using TEM and XRD. Oleic acid coating on nanoparticle is probed using FTIR for confirming the stability of ferrofluid. Thermal properties of mineral oil based ferrofluid with varying concentration of nanoparticles are evaluated in terms of thermal conductivity. It was found that the thermal conductivity of ferrofluid increases upto 2.5% (w/v) nanoparticle loading, where a maximum enhancement of ∼51% in thermal conductivity was recorded as compared to the base fluid.

Penicillium sp. strain that efficiently adsorbs lignosulfonate in the presence of sulfate ion.

Science.gov (United States)

Aoyama, Akihisa; Kurane, Ryuichiro; Nagai, Kazuo

2013-03-01

Lignin is one of the major water insoluble substances that support the physical properties of plants and can be solubilized by sulfite or alkaline treatment in accordance with pulpification. The lignin derivatives produced by both the sulfite and the kraft processes are called lignosulfonate (LS) and kraft lignin (KL), respectively, and both derivatives show a broad spectrum of optical absorbance from ultraviolet to visible light. When the spore suspension of an isolated Penicillium sp., Penicillium sp. A, was inoculated to a medium containing 0.1% commercial LS, absorbance at 480 nm (A480) almost completely disappeared after 5 days of cultivation. Maximum decolorization of the culture broth was observed when the microbe was cultured in the 0.8% LS medium reaching 88%, and the amount of LS removed was calculated to be 7 g/L. In a similar assay with the dark-liquid containing KL, 80% of the A480 of a 20% (v/v) dark-liquid medium disappeared after 5 days of culturing and the amount of KL removed was calculated to be 2.9 g/L. These values significantly exceeded the previously reported amounts with respect to substrate concentration and decolorization. Furthermore, since similar results were obtained in the cases of both LS and KL, it is expected that the present strain is able to non-specifically adsorb a wide range of lignin derivatives, because most of the colored substances were recovered in the culture sediments. Thus, the strain can be used to clean up waste fluids containing water soluble lignin derivatives, adsorb lignin derivatives in waste fluids before dehydration. Copyright © 2012 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Highly selective determination of dopamine in the presence of ascorbic acid and serotonin at glassy carbon electrodes modified with carbon nanotubes dispersed in polyethylenimine.

Science.gov (United States)

Rodríguez, Marcela C; Rubianes, María D; Rivas, Gustavo A

2008-11-01

We report the highly selective and sensitive voltammetric dopamine quantification in the presence of ascorbic acid and serotonin by using glassy carbon electrodes modified with a dispersion of multi-wall carbon nanotubes (MWCNT) in polyethylenimine, PEI (GCE/MWCNT-PEI). The electrocatalytic activity of the MWCNT deposited on the glassy carbon electrode has allowed an important decrease in the overvoltages for the oxidation of ascorbic acid and dopamine, making possible a clear definition of dopamine, serotonin and ascorbic acid oxidation processes. The sensitivities for dopamine in the presence and absence of 1.0 mM ascorbic acid and serotonin were (2.18 +/- 0.03) x 10(5) microAM(-1) (r = 0.9998); and (2.10 +/- 0.07) x 10(5) miroAM(-1) (r=0.9985), respectively, demonstrating the excellent performance of the GCE/MWCNT-PEI. The detection limit for dopamine in the mixture was 9.2 x 10(-7) M. The R. S. D. for the determination of 50 microM dopamine using four different electrodes was 3.9% when modified with the same MWCNT/PEI dispersion, and 4.6% when using four different dispersions. The modified electrode has been successfully applied for recovery assays of dopamine in human blood serum. Therefore, the new sensor represents an interesting and promising alternative for the electrochemical quantification of neurotransmitters and other analytes of clinical interest.

Citric acid induced promoted dispersion of Pt on the support and enhanced catalytic activities for a Pt-based catalyst

Science.gov (United States)

Cheng, Tianqiong; Wang, Jianli; Wang, Suning; Cui, Yajuan; Zhang, Hailong; Yan, Shuang; Yuan, Shandong; Chen, Yaoqiang

2017-12-01

Citric acid (CA), as the chelating agent, was introduced to obtain the enhanced Pt dispersion and catalytic activities for the Pt-based catalysts supported on oxygen-storage material. The role and content of CA were investigated systematically. It was found that the citric acid-assisted catalysts showed better Pt dispersion and smaller nanoparticle size of Pt. Thus, the catalyst had lower reduction temperature, preferable thermostability and possessed more oxidation state of Pt species under the oxidation atmosphere. The citric acid-induced fresh catalysts were excellent to convert CO and the corresponding aged ones exhibited higher activities for the elimination of all the target pollutants. Among the aged catalysts, P2-a (the mole ratio of Pt/CA is 2:1) presented the best performance. Particularly, compared with the reference sample (Pc-a), the light-off temperatures (T50) of NO, HC and CO for P2-a decreased by 39 °C, 42 °C and 72 °C, respectively, and the full-conversion temperatures (T90) of NO, HC and CO for P2-a decreased by 44 °C, 44 °C and 48 °C, respectively. Therefore, this work provides a facile and valid method to manufacture advanced catalysts for purification of the vehicle exhaust in the future.

Enhancement of carvedilol solubility by solid dispersion technique using cyclodextrins, water soluble polymers and hydroxyl acid.

Science.gov (United States)

Yuvaraja, K; Khanam, Jasmina

2014-08-05

Aim of the present work is to enhance aqueous solubility of carvedilol (CV) by solid dispersion technique using wide variety of carriers such as: β-cyclodextrin (βCD), hydroxypropyl-β-cyclodextrin (HPβCD), tartaric acid (TA), polyvinyl pyrrolidone K-30 (PVP K-30) and poloxamer-407 (PLX-407). Various products of 'CV-solid dispersion' had been studied extensively in various pH conditions to check enhancement of solubility and dissolution characteristics of carvedilol. Any physical change upon interaction between CV and carriers was confirmed by instrumental analysis: XRD, DSC, FTIR and SEM. Negative change of Gibb's free energy and complexation constants (Kc, 75-240M(-1), for cyclodextrins and 1111-20,365M(-1), for PVP K-30 and PLX-407) were the evidence of stable nature of the binding between CV and carriers. 'Solubility enhancement factor' of ionized-CV was found high enough (340 times) with HPβCD in presence of TA. TA increases the binding efficiency of cyclodextrin and changing the pH of microenvironment in dissolution medium. In addition, ionization process was used to increase the apparent intrinsic solubility of drug. In vitro, dissolution time of CV was remarkably reduced in the solid dispersion system compared to that of pure drug. This may be attributed to increased wettability, dispersing ability and transformation of crystalline state of drug to amorphous one. Copyright © 2014 Elsevier B.V. All rights reserved.

Banding urea and lignosulfonate in corn (Zea mays L.) production and 15N recovery

International Nuclear Information System (INIS)

Alkanani, T.; MacKenzie, A.F.

1996-01-01

The use of urea in corn (Zea mays L.) production is common. Under current N fertilizer recommendations for corn, urea may have adverse effects on corn growth when applied in a band. The effects of ammonium lignosulfonate (LS) on corn growth and on N uptake from the banded application of urea and diammonium phosphate (DAP) mixtures were investigated on two soils from eastern Quebec. Field experiments were initiated in the first week of May 1991 on an Ormstown silty clay and a Ste. Rosalie clay soils (fine, mixed, nonacid, mesic Typic Humaquepts). Treatments were two rates of urea (30 and 90 kg urea-N ha -1 ) in a combination with DAP (14kg N ha 1 ), with or without banded fertilizer solutions of LS (8 kg N ha -1 ) applied at planting 5 cm to the side and 3 cm below the seed. A no treatment control was included. The low rate of urea compared with the unfertilized plots. When compared with the unfertilized treatment, the high rate of urea and DAP (no LS added) caused 10% increase in grain yield. However, addition of LS to the high rate of urea and DAP increase grain yield by band 20%. In general, LS significantly increased corn N uptake from urea on both soils. Separate 15 N field experiments were initiated in June 1991. Mean recovery of 15 N ranged from 17.8% to 30.9% of the applied labelled urea. The rate of urea-N banded had no significant effect on immobilization, but LS resulted in significantly less 15 N immobilized. These observations suggest that LS can reduce the biological immobilization of urea-N and increase the efficiency of urea fertilizer by reducing the negative effects of banding high levels of urea, while attaining benefits of band placement. (author). 29 refs., 6 tabs

Influence of the microwave technology on solid dispersions of mefenamic acid and flufenamic acid.

Directory of Open Access Journals (Sweden)

Sultan Alshehri

Full Text Available The present studies were undertaken to develop solvent-free solid dispersions (SDs for poorly soluble anti-inflammatory drugs mefenamic acid (MA and flufenamic acid (FFA in order to enhance their in vitro dissolution rate and in vivo anti-inflammatory effects. The SDs of MA and FFA were prepared using microwaves irradiation (MW technique. Different carriers such as Pluronic F127® (PL, Eudragit EPO® (EPO, polyethylene glycol 4000 (PEG 4000 and Gelucire 50/13 (GLU were used for the preparation of SDs. Prepared MW irradiated SDs were characterized physicochemically using differential scanning calorimetry (DSC, thermogravimetric analysis (TGA, Fourier transform infra-red (FT-IR spectroscopy, powder X-ray diffraction (PXRD and scanning electron microscopy (SEM. The physicochemical characteristics and drug release profile of SDs were compared with pure drugs. The results of DSC, TGA, FT-IR, PXRD and SEM showed that SDs were successfully prepared. In vitro dissolution rate of MA and FFA was remarkably enhanced by SDs in comparison with pure MA and FFA. The SDs of MA and FFA prepared using PEG 400 showed higher drug release profile in comparison with those prepared using PL, EPO or GLU. The dissolution efficiency for MA-PEG SD and FFA-PEG SD was obtained as 61.40 and 59.18%, respectively. Optimized SDs were also evaluated for in vivo anti-inflammatory effects in male Wistar rats. The results showed significant % inhibition by MA-PEG (87.74% after 4 h and FFA-PEG SDs (81.76% after 4 h in comparison with pure MA (68.09% after 4 h and pure FFA (55.27% after 4 h (P<0.05. These results suggested that MW irradiated SDs of MA and FFA could be successfully used for the enhancement of in vitro dissolution rate and in vivo therapeutic efficacy of both drugs.

Dispersion and stabilization of cochleate nanoparticles.

Science.gov (United States)

Bozó, Tamás; Wacha, András; Mihály, Judith; Bóta, Attila; Kellermayer, Miklós S Z

2017-08-01

Cochleates, calcium-stabilized membrane rolls of nanoscale diameter, promise a unique and efficient way of delivering lipid-soluble drugs, proteins or nucleic acids into biological systems because they protect the encapsulated material against enzymatic or chemical degradation. Self-aggregation, which typically arises during production and storage is a major obstacle that has so far precluded the development of an efficient cochleate-based drug-delivery system. Here we show that citric acid, added transiently in a narrow concentration range, effectively disperses cochleate aggregates, stabilizes the disperse state for long-term storage and preserves the canonical ultrastructure and topological characteristics of cochleate nanoparticles. Copyright © 2017 Elsevier B.V. All rights reserved.

Controlling the Molecular Weight of Lignosulfonates by an Alkaline Oxidative Treatment at Moderate Temperatures and Atmospheric Pressure: A Size-Exclusion and Reverse-Phase Chromatography Study

Directory of Open Access Journals (Sweden)

Chamseddine Guizani

2017-11-01

Full Text Available The molecular weights of lignosulfonates (LSs are modified by a rather simple process involving an alkaline oxidative treatment at moderate temperatures (70–90 °C and atmospheric pressure. Starting from LSs with an average molecular weight of 90,000 Da, and using such a treatment, one can prepare controlled molecular weight LSs in the range of 30,000 to 3500 Da based on the average mass molecular weight. The LS depolymerisation was monitored via reverse-phase and size-exclusion chromatography. It has been shown that the combination of O2, H2O2 and Cu as a catalyst in alkaline conditions at 80 °C induces a high LS depolymerisation. The depolymerisation was systemically accompanied by a vanillin production, the yields of which reached 1.4 wt % (weight percentage on LS raw basis in such conditions. Also, the average molecular weight and vanillin concentration were correlated and depended linearly on the temperature and reaction duration.

46 CFR Table II to Part 150 - Grouping of Cargoes

Science.gov (United States)

2010-10-01

... solution Potassium oleate Potassium salt of polyolefin acid Propyl acetate Propylene carbonate Propylene... lignosulfonate solution Sodium polyacrylate solution 2 Sodium salt of Ferric hydroxyethylethylenediamine... 46 Shipping 5 2010-10-01 2010-10-01 false Grouping of Cargoes II Table II to Part 150 Shipping...

Polymer Inclusion Membranes with Strip Dispersion

Directory of Open Access Journals (Sweden)

Yueh-Hsien Li

2017-06-01

Full Text Available The present work investigated the permeation of indium ions through a polymer inclusion membrane (PIM, prepared with cellulose triacetate (CTA as the base polymer, tris(2-butoxyethyl phosphate (TBEP as the plasticizer and di-(2-ethylhexylphosphoric acid (D2EHPA as the extractant. With 5 M HCl aqueous solution as the strip solution, we observed an initial indium permeability of 2.4 × 10−4 m/min. However, the permeability decreases with time, dropping to about 3.4 × 10−5 m/min after 200 min of operation. Evidence was obtained showing that hydrolysis of CTA occurred, causing a dramatic decrease in the feed pH (protons transported from strip to feed solutions and a loss of extractant and plasticizer from the membrane, and then leading to the loss of indium permeability. To alleviate the problem of hydrolysis, we proposed an operation scheme called polymer inclusion membranes with strip dispersion: dispersing the strip solution in extractant-containing oil and then bringing the dispersion to contact with the polymer membrane. Since the strong acid was dispersed in oil, the membrane did not directly contact the strong acid at all times, and membrane hydrolysis was thus alleviated and the loss of indium permeability was effectively prevented. With the proposed scheme, a stable indium permeability of 2.5 × 10−4 m/min was obtained during the whole time period of the permeation experiment.

The characteristic and dispersion stability of nanocellulose produced by mixed acid hydrolysis and ultrasonic assistance.

Science.gov (United States)

Niu, Fuge; Li, Mengya; Huang, Qi; Zhang, Xiuzhen; Pan, Weichun; Yang, Jiansheng; Li, Jianrong

2017-06-01

Axiolitic shape nanocellulose particles were prepared using a combined mixed acid hydrolysis and ultrasonic treatment. The crystallinity, morphology and stability properties of cellulose were characterized to investigate the mechanism of nanocellulose formation and stability. It was found the hydrodynamic radius decreased from 205nm to 89nm, and the crystallinity index of the nanocellulose increased from 62.90% to 72.31% with an increase in hydrolysis time from 2 to 10h. Sulfate esters and sulfonate group were present in the nanocellulose, and released more COH groups after hydrolysis. The ζ-potential of cellulose decreased from -11.5 to -43.8mV after 10h of hydrolysis. These results illustrated the amorphous characteristic of cellulose was removed after acid hydrolysis and ultrasonic treatment. The higher ζ-potential and relatively small cellulose particles caused a more stable suspension, suggesting that electrostatic interactions played an important role in maintaining the stability and dispersibility of the nanocellulose particles. Copyright © 2017 Elsevier Ltd. All rights reserved.

Preparation and investigation of mefenamic acid - polyethylene glycol - sucrose ester solid dispersions.

Science.gov (United States)

Fülöp, Ibolya; Gyéresi, Árpád; Kiss, Lóránd; Deli, Mária A; Croitoru, Mircea Dumitru; Szabó-Révész, Piroska; Aigner, Zoltán

2015-12-01

Mefenamic acid (MA) is a widely used non-steroidal antiinflammatory (NSAID) drug. The adverse effects typical of NSAIDs are also present in the case of MA, partly due to its low water solubility. The aim of this study was to increase the water solubility of MA in order to influence its absorption and bioavailability. Solid dispersions of MA were prepared by the melting method using polyethylene glycol 6000 and different types (laurate, D-1216; palmitate, P-1670; stearate, S-1670) and amounts of sucrose esters as carriers. The X-ray diffraction results show that MA crystals were not present in the products. Dissolution tests carried out in artificial intestinal juice showed that the product containing 10 % D-1216 increased water solubility about 3 times. The apparent permeability coefficient of MA across human Caco-2 intestinal epithelial cell layers was high and, despite the difference in solubility, there was no further increase in drug penetration in the presence of the applied additives.

Dispersion of multi-wall carbon nanotubes in polyhistidine: Characterization and analytical applications

International Nuclear Information System (INIS)

Dalmasso, Pablo R.; Pedano, María L.; Rivas, Gustavo A.

2012-01-01

Highlights: ► Polyhistidine (Polyhis) is an efficient dispersing agent of MWCNT. ► MWCNT/Polyhis ratio and sonication time are critical variables when dispersing MWCNT. ► MWCNT–Polyhis deposited at GCE largely catalyzes the oxidation of ascorbic acid. ► GCE/MWCNT–Polyhis allows the selective and sensitive quantification of UA and Do. - Abstract: We report for the first time the use of polyhistidine (Polyhis) to efficiently disperse multiwall carbon nanotubes (MWCNTs). The optimum dispersion MWCNT–Polyhis was obtained by sonicating for 30 min 1.0 mg mL −1 MWCNTs in 0.25 mg mL −1 Polyhis solution prepared in 75:25 (v/v) ethanol/0.200 M acetate buffer solution pH 5.00. The dispersion was characterized by scanning electron microscopy, and by cyclic voltammetry and amperometry using ascorbic acid as redox marker. The modification of glassy carbon electrodes with MWCNT–Polyhis produces a drastic decrease in the overvoltage for the oxidation of ascorbic acid (580 mV) at variance with the response observed at glassy carbon electrodes modified just with Polyhis, where the charge transfer is more difficult due to the blocking effect of the polymer. The reproducibility for the sensitivities obtained after 10 successive calibration plots using the same surface was 6.3%. The MWCNT-modified glassy carbon electrode demonstrated to be highly stable since after 45 days storage at room temperature the response was 94.0% of the original. The glassy carbon electrode modified with MWCNT–Polyhis dispersion was successfully used to quantify dopamine or uric acid at nanomolar levels, even in the presence of large excess of ascorbic acid. Determinations of uric acid in human blood serum samples demonstrated a very good correlation with the value reported by Wienner laboratory.

Dispersion of multi-wall carbon nanotubes in polyhistidine: Characterization and analytical applications

Energy Technology Data Exchange (ETDEWEB)

Dalmasso, Pablo R. [INFIQC, Departamento de Fisicoquimica, Facultad de Ciencias Quimicas, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000 Cordoba (Argentina); Pedano, Maria L., E-mail: mlpedano@fcq.unc.edu.ar [INFIQC, Departamento de Fisicoquimica, Facultad de Ciencias Quimicas, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000 Cordoba (Argentina); Rivas, Gustavo A., E-mail: grivas@mail.fcq.unc.edu.ar [INFIQC, Departamento de Fisicoquimica, Facultad de Ciencias Quimicas, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000 Cordoba (Argentina)

2012-01-13

Highlights: Black-Right-Pointing-Pointer Polyhistidine (Polyhis) is an efficient dispersing agent of MWCNT. Black-Right-Pointing-Pointer MWCNT/Polyhis ratio and sonication time are critical variables when dispersing MWCNT. Black-Right-Pointing-Pointer MWCNT-Polyhis deposited at GCE largely catalyzes the oxidation of ascorbic acid. Black-Right-Pointing-Pointer GCE/MWCNT-Polyhis allows the selective and sensitive quantification of UA and Do. - Abstract: We report for the first time the use of polyhistidine (Polyhis) to efficiently disperse multiwall carbon nanotubes (MWCNTs). The optimum dispersion MWCNT-Polyhis was obtained by sonicating for 30 min 1.0 mg mL{sup -1} MWCNTs in 0.25 mg mL{sup -1} Polyhis solution prepared in 75:25 (v/v) ethanol/0.200 M acetate buffer solution pH 5.00. The dispersion was characterized by scanning electron microscopy, and by cyclic voltammetry and amperometry using ascorbic acid as redox marker. The modification of glassy carbon electrodes with MWCNT-Polyhis produces a drastic decrease in the overvoltage for the oxidation of ascorbic acid (580 mV) at variance with the response observed at glassy carbon electrodes modified just with Polyhis, where the charge transfer is more difficult due to the blocking effect of the polymer. The reproducibility for the sensitivities obtained after 10 successive calibration plots using the same surface was 6.3%. The MWCNT-modified glassy carbon electrode demonstrated to be highly stable since after 45 days storage at room temperature the response was 94.0% of the original. The glassy carbon electrode modified with MWCNT-Polyhis dispersion was successfully used to quantify dopamine or uric acid at nanomolar levels, even in the presence of large excess of ascorbic acid. Determinations of uric acid in human blood serum samples demonstrated a very good correlation with the value reported by Wienner laboratory.

Physicochemical characterization of tacrolimus-loaded solid dispersion with sodium carboxylmethyl cellulose and sodium lauryl sulfate.

Science.gov (United States)

Park, Young-Joon; Ryu, Dong-Sung; Li, Dong Xun; Quan, Qi Zhe; Oh, Dong Hoon; Kim, Jong Oh; Seo, Youn Gee; Lee, Young-Im; Yong, Chul Soon; Woo, Jong Soo; Choi, Han-Gon

2009-06-01

To develop a novel tacrolimus-loaded solid dispersion with improved solubility, various solid dispersions were prepared with various ratios of water, sodium lauryl sulfate, citric acid and carboxylmethylcellulose-Na using spray drying technique. The physicochemical properties of solid dispersions were investigated using scanning electron microscopy, differential scanning calorimetery and powder X-ray diffraction. Furthermore, their solubility and dissolution were evaluated compared to drug powder. The solid dispersion at the tacrolimus/CMC-Na/sodium lauryl sulfate/citric acid ratio of 3/24/3/0.2 significantly improved the drug solubility and dissolution compared to powder. The scanning electron microscopy result suggested that carriers might be attached to the surface of drug in this solid dispersion. Unlike traditional solid dispersion systems, the crystal form of drug in this solid dispersion could not be converted to amorphous form, which was confirmed by the analysis of DSC and powder X-ray diffraction. Thus, the solid dispersion system with water, sodium lauryl sulfate, citric acid and CMC-Na should be a potential candidate for delivering a poorly water-soluble tacrolimus with enhanced solubility and no convertible crystalline.

Determination of phenolic acids and flavonoids in raw propolis by silica-supported ionic liquid-based matrix solid phase dispersion extraction high performance liquid chromatography-diode array detection.

Science.gov (United States)

Wang, Zhibing; Sun, Rui; Wang, Yuanpeng; Li, Na; Lei, Lei; Yang, Xiao; Yu, Aimin; Qiu, Fangping; Zhang, Hanqi

2014-10-15

The silica-supported ionic liquid (S-SIL) was prepared by impregnation and used as the dispersion adsorbent of matrix solid phase dispersion (MSPD) for the simultaneous extraction of eight phenolic acids and flavonoids, including caffeic acid, ferulic acid, morin, luteolin, quercetin, apigenin, chrysin, and kaempferide in raw propolis. High performance liquid chromatography with a Zorbax SB-C18 column (150mm×4.6mm, 3.5μm) was used for separation of the analytes. The mobile phase consisted of 0.2% phosphoric acid aqueous solution and acetonitrile and the flow rate of the mobile phase was 0.5mL/min. The experimental conditions for silica-supported ionic liquid-based matrix solid phase dispersion (S-SIL-based MSPD) were optimized. S-SIL containing 10% [C6MIM]Cl was used as dispersant, 20mL of n-hexane as washing solvent and 15mL of methanol as elution solvent. The ratio of S-SIL to sample was selected to be 4:1. The standard curves showed good linear relationship (r>0.9995). The limits of detection and quantification were in the range of 5.8-22.2ngmL(-1) and 19.2-74.0ngmL(-1), respectively. The relative standard deviations (RSDs) of intra-day and inter-day determination were lower than 8.80% and 11.19%, respectively. The recoveries were between 65.51% and 92.32% with RSDs lower than 8.95%. Compared with ultrasound-assisted extraction (UAE) and soxhlet extraction, the present method consumed less sample, organic solvent, and extraction time, although the extraction yields obtained by S-SIL-based MSPD are slightly lower than those obtained by UAE. Copyright © 2014 Elsevier B.V. All rights reserved.

Assessment of protein quality of soybean meal and 00-rapeseed meal toasted in the presence of lignosulfonate by amino acid digestibility in growing pigs and Maillard reaction products.

Science.gov (United States)

Hulshof, T G; Bikker, P; van der Poel, A F B; Hendriks, W H

2016-03-01

An experiment was conducted to determine protein quality in processed protein sources using the content of AA, -methylisourea (OMIU)-reactive Lys, Maillard reaction products (MRP), and cross-link products; the standardized ileal digestibility (SID) of CP and AA; and growth performance in growing pigs as criteria. Differences in protein quality were created by secondary toasting (at 95°C for 30 min) of soybean meal (SBM) and rapeseed meal (RSM) in the presence of lignosulfonate resulting in processed SBM (pSBM) and processed RSM (pRSM). The processing treatment was used as a model for overprocessed protein sources. Ten growing pigs were each fed 1 of the 4 diets containing SBM, pSBM, RSM, or pRSM in each of 3 periods. Ileal chyme was collected at the end of each period and analyzed for CP, AA, and OMIU-reactive Lys. Diets were analyzed for furosine and carboxymethyllysine (CML) as an indicator for MRP and lysinoalanine (LAL), which is a cross-link product. The SBM and RSM diets contained furosine, CML, and LAL, indicating that the Maillard reaction and cross-linking had taken place in SBM and RSM, presumably during the oil extraction/desolventizing process. The amounts of furosine, CML, and LAL were elevated in pSBM and pRSM due to further processing. Processing resulted in a reduction in total and OMIU-reactive Lys contents and a decrease in G:F from 0.52 to 0.42 for SBM and 0.46 to 0.39 for RSM ( = 0.006), SID of CP from 83.9 to 71.6% for SBM and 74.9 to 64.6% for RSM ( < 0.001), and SID of AA ( < 0.001), with the largest effects for total and OMIU-reactive Lys. The effects of processing could be substantial and should be taken into account when using processed protein sources in diets for growing pigs. The extent of protein damage may be assessed by additional analyses of MRP and cross-link products.

Graft polymerization of acrylic acid onto chitin nanofiber to improve dispersibility in basic water.

Science.gov (United States)

Ifuku, Shinsuke; Iwasaki, Masayoshi; Morimoto, Minoru; Saimoto, Hiroyuki

2012-09-01

Graft copolymerization of acrylic acid (AA) on chitin nanofibers was carried out with potassium persulfate as a free radical initiator in an aqueous medium. The molar ratio of grafted AA increased with the AA concentration. The grafted chitin nanofibers were characterized by FT-IR, FE-SEM, UV-vis, XRD, and TGA. After polymerization, the characteristic morphology of chitin nanofibers was maintained. Chitin nanofibers grafted with AA were efficiently dissociated and dispersed homogeneously in basic water because of the electrostatic repulsion effect between nanofibers. AA was grafted on the surface and amorphous part of chitin nanofibers, and the original crystalline structure of α-chitin was maintained. At 330 °C, the weight residue of the graft copolymer increased with the grafted AA content. Copyright © 2012 Elsevier Ltd. All rights reserved.

SANS observations on weakly flocculated dispersions

DEFF Research Database (Denmark)

Mischenko, N.; Ourieva, G.; Mortensen, K.

1997-01-01

Structural changes occurring in colloidal dispersions of poly-(methyl metacrylate) (PMMA) particles, sterically stabilized with poly-(12-hydroxystearic acid) (PHSA), while varying the solvent quality, temperature and shear rate, are investigated by small-angle neutron scattering (SANS......). For a moderately concentrated dispersion in a marginal solvent the transition on cooling from the effective stability to a weak attraction is monitored, The degree of attraction is determined in the framework of the sticky spheres model (SSM), SANS and rheological results are correlated....

Degradation of chitosan hydrogel dispersed in dilute carboxylic acids by solution plasma and evaluation of anticancer activity of degraded products

Science.gov (United States)

Chokradjaroen, Chayanaphat; Rujiravanit, Ratana; Theeramunkong, Sewan; Saito, Nagahiro

2018-01-01

Chitosan is a polysaccharide that has been extensively studied in the field of biomedicine, especially its water-soluble degraded products called chitooligosaccharides (COS). In this study, COS were produced by the degradation of chitosan hydrogel dispersed in a dilute solution (i.e., 1.55 mM) of various kinds of carboxylic acids using a non-thermal plasma technology called solution plasma (SP). The degradation rates of chitosan were influenced by the type of carboxylic acids, depending on the interaction between chitosan and each carboxylic acid. After SP treatment, the water-soluble degraded products containing COS could be easily separated from the water-insoluble residue of chitosan hydrogel by centrifugation. The production yields of the COS were mostly higher than 55%. Furthermore, the obtained COS products were evaluated for their inhibitory effect as well as their selectivity against human lung cancer cells (H460) and human lung normal cells (MRC-5).

Surface chemical compositions and dispersity of starch nanocrystals formed by sulfuric and hydrochloric acid hydrolysis.

Science.gov (United States)

Wei, Benxi; Xu, Xueming; Jin, Zhengyu; Tian, Yaoqi

2014-01-01

Surface chemical compositions of starch nanocrystals (SNC) prepared using sulfuric acid (H2SO4) and hydrochloric acid (HCl) hydrolysis were analyzed by X-ray photoelectron spectroscopy (XPS) and FT-IR. The results showed that carboxyl groups and sulfate esters were presented in SNC after hydrolysis with H2SO4, while no sulfate esters were detected in SNC during HCl-hydrolysis. TEM results showed that, compared to H2SO4-hydrolyzed sample, a wider size distribution of SNC prepared by HCl-hydrolysis were observed. Zeta-potentials were -23.1 and -5.02 mV for H2SO4- and HCl-hydrolyzed SNC suspensions at pH 6.5, respectively. Nevertheless, the zeta-potential values decreased to -32.3 and -10.2 mV as the dispersion pH was adjusted to 10.6. After placed 48 h at pH 10.6, zeta-potential increased to -24.1 mV for H2SO4-hydrolyzed SNC, while no change was detected for HCl-hydrolyzed one. The higher zeta-potential and relative small particle distribution of SNC caused more stable suspensions compared to HCl-hydrolyzed sample.

Surface chemical compositions and dispersity of starch nanocrystals formed by sulfuric and hydrochloric acid hydrolysis.

Directory of Open Access Journals (Sweden)

Benxi Wei

Full Text Available Surface chemical compositions of starch nanocrystals (SNC prepared using sulfuric acid (H2SO4 and hydrochloric acid (HCl hydrolysis were analyzed by X-ray photoelectron spectroscopy (XPS and FT-IR. The results showed that carboxyl groups and sulfate esters were presented in SNC after hydrolysis with H2SO4, while no sulfate esters were detected in SNC during HCl-hydrolysis. TEM results showed that, compared to H2SO4-hydrolyzed sample, a wider size distribution of SNC prepared by HCl-hydrolysis were observed. Zeta-potentials were -23.1 and -5.02 mV for H2SO4- and HCl-hydrolyzed SNC suspensions at pH 6.5, respectively. Nevertheless, the zeta-potential values decreased to -32.3 and -10.2 mV as the dispersion pH was adjusted to 10.6. After placed 48 h at pH 10.6, zeta-potential increased to -24.1 mV for H2SO4-hydrolyzed SNC, while no change was detected for HCl-hydrolyzed one. The higher zeta-potential and relative small particle distribution of SNC caused more stable suspensions compared to HCl-hydrolyzed sample.

Surface Chemical Compositions and Dispersity of Starch Nanocrystals Formed by Sulfuric and Hydrochloric Acid Hydrolysis

Science.gov (United States)

Wei, Benxi; Xu, Xueming; Jin, Zhengyu; Tian, Yaoqi

2014-01-01

Surface chemical compositions of starch nanocrystals (SNC) prepared using sulfuric acid (H2SO4) and hydrochloric acid (HCl) hydrolysis were analyzed by X-ray photoelectron spectroscopy (XPS) and FT-IR. The results showed that carboxyl groups and sulfate esters were presented in SNC after hydrolysis with H2SO4, while no sulfate esters were detected in SNC during HCl-hydrolysis. TEM results showed that, compared to H2SO4-hydrolyzed sample, a wider size distribution of SNC prepared by HCl-hydrolysis were observed. Zeta-potentials were −23.1 and −5.02 mV for H2SO4- and HCl-hydrolyzed SNC suspensions at pH 6.5, respectively. Nevertheless, the zeta-potential values decreased to −32.3 and −10.2 mV as the dispersion pH was adjusted to 10.6. After placed 48 h at pH 10.6, zeta-potential increased to −24.1 mV for H2SO4-hydrolyzed SNC, while no change was detected for HCl-hydrolyzed one. The higher zeta-potential and relative small particle distribution of SNC caused more stable suspensions compared to HCl-hydrolyzed sample. PMID:24586246

Adsorption of an anionic dispersant on lignite

Energy Technology Data Exchange (ETDEWEB)

Yavuz, R.; Kucukbayrak, S. [Istanbul Technical University, Istanbul (Turkey). Dept. of Chemical Engineering, Chemical & Metallurgical Engineering Faculty

2001-12-01

Since coal is not a homogeneous substance but a mixture of carbonaceous materials and mineral matter, it has a variety of surface properties. Therefore, it is not easy to control the properties of coal suspensions by simply adjusting variables, such as pH and/or electrolyte. A chemical agent needs to be added to control the properties of the coal suspensions. The adsorption behavior of an anionic dispersant in the presence of a wetting agent using some Turkish lignite samples was investigated. The effects of dispersant concentration, temperature and pH on the dispersant adsorption were studied systematically, and the experimental results are presented. Pellupur B69 as a dispersant, commercial mixture of formaldehyde condensate sodium salt of naphthalene sulphonic acid, and Texapon N{sub 2}5 as a wetting agent, a sodium lauryl ether sulfate, have been used.

Development of a method for environmentally friendly chemical peptide synthesis in water using water-dispersible amino acid nanoparticles

Directory of Open Access Journals (Sweden)

Fukumori Yoshinobu

2011-08-01

Full Text Available Abstract Due to the vast importance of peptides in biological processes, there is an escalating need for synthetic peptides to be used in a wide variety of applications. However, the consumption of organic solvent is extremely large in chemical peptide syntheses because of the multiple condensation steps in organic solvents. That is, the current synthesis method is not environmentally friendly. From the viewpoint of green sustainable chemistry, we focused on developing an organic solvent-free synthetic method using water, an environmentally friendly solvent. Here we described in-water synthesis technology using water-dispersible protected amino acids.

Effectiveness of selected dispersants on magnetite deposition at simulated PWR heat transfer surfaces

International Nuclear Information System (INIS)

Burgmayer, P.; Crovetto, R.; Turner, C.; Klimas, S.

1998-01-01

The effectiveness of three different dispersants - a polyphosphonic acid (PIPPA); a polymethacrylic acid (PMA); and a hydroxyethylidene methacrylic acid (HEME) - at controlling magnetite deposition has been examined under steam generator operating conditions. Tests in a cycling research model boiler showed that the dispersants resulted in corrosion products with a smaller average size and a bimodal size distribution. At a concentration in the boiler of 10 mg/kg, density weight deposit on heated probes was reduced 4-, 3-, and 2-fold for PMA, PIPPA, and HEME, respectively. PIPPA was the most effective at increasing iron transport out of the boiler. In deposition loop tests using a 59-Fe radiotracer, only PIPPA and HEME were effective at reducing the particle deposition rate under flow-boiling conditions. None of the dispersants had any impact on deposition under single-phase forced-convective flow. (author)

Effectiveness of selected dispersants on magnetite deposition at simulated PWR heat-transfer surfaces

International Nuclear Information System (INIS)

Burgmayer, P.; Crovetto, R.; Turner, C.; Klimas, S.J.

1999-07-01

The effectiveness of 3 different dispersants-a polyphosphonic acid (PIPPA), a polymethacrylic acid (PMA), and a hydroxyethylidene methacrylic acid (HEME)-at controlling magnetite deposition was examined under steam generator operating conditions. Tests in a cycling research model boiler showed that the dispersants resulted in corrosion products of a smaller average size and a bimodal size distribution. At a concentration in the boiler of 10 mg/kg, density weight deposit on heated probes was reduced 4-, 3-, and 2-fold for PMA, PIPPA, and HEME, respectively. PIPPA was the most effective at increasing iron transport out of the boiler. In deposition loop tests using an 59 Fe radiotracer, only PIPPA and HEME were effective at reducing the particle deposition rate under flow-boiling conditions. None of the dispersants had any effect on deposition under single-phase forced-convective flow. (author)

Effectiveness of selected dispersants on magnetite deposition at simulated PWR heat transfer surfaces

Energy Technology Data Exchange (ETDEWEB)

Burgmayer, P.; Crovetto, R. [Betz Dearborn Labs., Revose, PA (United States); Turner, C.; Klimas, S. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

1998-07-01

The effectiveness of three different dispersants - a polyphosphonic acid (PIPPA); a polymethacrylic acid (PMA); and a hydroxyethylidene methacrylic acid (HEME) - at controlling magnetite deposition has been examined under steam generator operating conditions. Tests in a cycling research model boiler showed that the dispersants resulted in corrosion products with a smaller average size and a bimodal size distribution. At a concentration in the boiler of 10 mg/kg, density weight deposit on heated probes was reduced 4-, 3-, and 2-fold for PMA, PIPPA, and HEME, respectively. PIPPA was the most effective at increasing iron transport out of the boiler. In deposition loop tests using a 59-Fe radiotracer, only PIPPA and HEME were effective at reducing the particle deposition rate under flow-boiling conditions. None of the dispersants had any impact on deposition under single-phase forced-convective flow. (author)

Effectiveness of selected dispersants on magnetite deposition at simulated PWR heat-transfer surfaces

Energy Technology Data Exchange (ETDEWEB)

Burgmayer, P.; Crovetto, R. [Betz Dearborn Labs., Revose, PA (United States); Turner, C.; Klimas, S.J

1999-07-01

The effectiveness of 3 different dispersants-a polyphosphonic acid (PIPPA), a polymethacrylic acid (PMA), and a hydroxyethylidene methacrylic acid (HEME)-at controlling magnetite deposition was examined under steam generator operating conditions. Tests in a cycling research model boiler showed that the dispersants resulted in corrosion products of a smaller average size and a bimodal size distribution. At a concentration in the boiler of 10 mg/kg, density weight deposit on heated probes was reduced 4-, 3-, and 2-fold for PMA, PIPPA, and HEME, respectively. PIPPA was the most effective at increasing iron transport out of the boiler. In deposition loop tests using an {sup 59}Fe radiotracer, only PIPPA and HEME were effective at reducing the particle deposition rate under flow-boiling conditions. None of the dispersants had any effect on deposition under single-phase forced-convective flow. (author)

Preparation and investigation of mefenamic acid – polyethylene glycol – sucrose ester solid dispersions

Directory of Open Access Journals (Sweden)

Fülöp Ibolya

2015-12-01

Full Text Available Mefenamic acid (MA is a widely used non-steroidal antiinflammatory (NSAID drug. The adverse effects typical of NSAIDs are also present in the case of MA, partly due to its low water solubility. The aim of this study was to increase the water solubility of MA in order to influence its absorption and bioavailability. Solid dispersions of MA were prepared by the melting method using polyethylene glycol 6000 and different types (laurate, D-1216; palmitate, P-1670; stearate, S-1670 and amounts of sucrose esters as carriers. The X-ray diffraction results show that MA crystals were not present in the products. Dissolution tests carried out in artificial intestinal juice showed that the product containing 10 % D-1216 increased water solubility about 3 times. The apparent permeability coefficient of MA across human Caco-2 intestinal epithelial cell layers was high and, despite the difference in solubility, there was no further increase in drug penetration in the presence of the applied additives.

Nanostructured aqueous dispersions of citrem interacting with lipids and PEGylated lipids

DEFF Research Database (Denmark)

Hedegaard, S.F.; Nilsson, Christa; Laurinmäki, P.

2013-01-01

We report on the formation of nanostructured aqueous dispersions based on the negatively charged food-grade emulsifier citrem (citric acid esters of mono- and diglycerides). To our knowledge, this is the first report in the literature on the spontaneous formation of aqueous PEGylated and non-PEGy...... ) phase. Based on the SAXS results, the partial replacement of citrem by high amount of MO or PHYT induced the formation of hexosomes. The investigated dispersions of citrem could be attractive as nanocarriers of poorly water-soluble drugs and functional foods.......We report on the formation of nanostructured aqueous dispersions based on the negatively charged food-grade emulsifier citrem (citric acid esters of mono- and diglycerides). To our knowledge, this is the first report in the literature on the spontaneous formation of aqueous PEGylated and non...

Radiation-curable coatings containing reactive pigment dispersants

International Nuclear Information System (INIS)

Ansel, R.E.

1985-01-01

Liquid coating compositions adapted to be cured by exposure to penetrating radiation are disclosed in which a liquid vehicle of coating viscosity having an ethylenically unsaturated portion comprising one or more polyethylenically unsaturated materials adapted to cure on radiation exposure, pigment dispersed in the vehicle, and an ethylenically unsaturated radiation-curable dispersant containing a carboxyl group for wetting the pigment and assisting in the stable dipsersion of the pigment in the vehicle. This dispersant is a half amide or half ester of an ethylenically unsaturated polycarboxylic acid anhydride, such as maleic anhydride, with an organic compound having a molecular weight of from 100 to 4000 and which contains a single hydroxy group or a single amino group as the sole reactive group thereof

Stability of nano-metric colloidal dispersions of titanium: effect of surface complexation

International Nuclear Information System (INIS)

Peyre, Veronique

1996-01-01

This research thesis reports the study of the adsorption of small organic molecules at the surface of nano-particles of mineral oxides (zirconia), and of its effects on the stability of the colloidal dispersion. Adsorption has been quantified by adsorption isotherms and surface titrations. Processes and mechanisms are thus discussed with respect to pH. The influence of various protecting molecules (acetyl acetone, but also acetic acid, citric acid and diethanolamine) has been studied, and notably highlighted the role of the outer face of the complexing agent in the assessment of reactions between particles which govern the compression and re-dispersability properties of protected dispersions. This study is performed by osmotic pressure measurements and by X-ray diffusion at small angles, completed by statistical mechanics calculations [fr

Enhanced solubility and bioavailability of sibutramine base by solid dispersion system with aqueous medium.

Science.gov (United States)

Li, Dong Xun; Jang, Ki-Young; Kang, Wonku; Bae, Kyoungjin; Lee, Mann Hyung; Oh, Yu-Kyoung; Jee, Jun-Pil; Park, Young-Joon; Oh, Dong Hoon; Seo, Youn Gee; Kim, Young Ran; Kim, Jong Oh; Woo, Jong Soo; Yong, Chul Soon; Choi, Han-Gon

2010-01-01

To develop a novel sibutramine base-loaded solid dispersion with improved solubility bioavailability, various solid dispersions were prepared with water, hydroxypropylmethyl cellulose (HPMC), poloxamer and citric acid using spray-drying technique. The effect of HPMC, poloxamer and citric acid on the aqueous solubility of sibutramine was investigated. The physicochemical properties of solid dispersion were investigated using scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and X-ray powder diffraction. The dissolution and pharmacokinetics in rats of solid dispersion were evaluated compared to the sibutramine hydrochloride monohydrate-loaded commercial product (Reductil). The sibutramine base-loaded solid dispersion gave two type forms. Like conventional solid dispersion system, one type appeared as a spherical shape with smooth surface, as the carriers and drug with relatively low melting point were soluble in water and formed it. The other appeared as an irregular form with relatively rough surface. Unlike conventional solid dispersion system, this type changed no crystalline form of drug. Our results suggested that this type was formed by attaching hydrophilic carriers to the surface of drug without crystal change, resulting from changing the hydrophobic drug to hydrophilic form. The sibutramine-loaded solid dispersion at the weight ratio of sibutramine base/HPMC/poloxamer/citric acid of 5/3/3/0.2 gave the maximum drug solubility of about 3 mg/ml. Furthermore, it showed the similar plasma concentration, area under the curve (AUC) and C(max) of parent drug, metabolite I and II to the commercial product, indicating that it might give the similar drug efficacy compared to the sibutramine hydrochloride monohydrate-loaded commercial product in rats. Thus, this solid dispersion system would be useful to deliver poorly water-soluble sibutramine base with enhanced bioavailability.

Theoretical study of adsorption of amino acids on graphene and BN sheet in gas and aqueous phase with empirical DFT dispersion correction.

Science.gov (United States)

Singla, Preeti; Riyaz, Mohd; Singhal, Sonal; Goel, Neetu

2016-02-21

Understanding interactions of biomolecules with nanomaterials at the molecular level is crucial to design new materials for practical use. In the present study, adsorption of three distinct types of amino acids, namely, valine, arginine and aspartic acid, over the surface of structurally analogous but chemically different graphene and BN nanosheets has been explored within the formalism of DFT. The explicit dispersion correction incorporated in the computational methodology improves the accuracy of the results by accounting for long range van der Waals interactions and is essential for agreement with experimental values. The real biological environment has been mimicked by re-optimizing all the model structures in an aqueous medium. The study provides ample evidence in terms of adsorption energy, solvation energy, separation distance and charge analysis to conclude that both the nano-surfaces adsorb the amino acids with release of energy and there are no bonded interactions between the two. The polarity of the BN nanosheet provides it an edge over the graphene surface to have more affinity towards amino acids.

Aqueous Dispersions of Silica Stabilized with Oleic Acid Obtained by Green Chemistry.

Science.gov (United States)

Nistor, Cristina Lavinia; Ianchis, Raluca; Ghiurea, Marius; Nicolae, Cristian-Andi; Spataru, Catalin-Ilie; Culita, Daniela Cristina; Pandele Cusu, Jeanina; Fruth, Victor; Oancea, Florin; Donescu, Dan

2016-01-05

The present study describes for the first time the synthesis of silica nanoparticles starting from sodium silicate and oleic acid (OLA). The interactions between OLA and sodium silicate require an optimal OLA/OLANa molar ratio able to generate vesicles that can stabilize silica particles obtained by the sol-gel process of sodium silicate. The optimal molar ratio of OLA/OLANa can be ensured by a proper selection of OLA and respectively of sodium silicate concentration. The titration of sodium silicate with OLA revealed a stabilization phenomenon of silica/OLA vesicles and the dependence between their average size and reagent's molar ratio. Dynamic light scattering (DLS) and scanning electron microscopy (SEM) measurements emphasized the successful synthesis of silica nanoparticles starting from renewable materials, in mild condition of green chemistry. By grafting octadecyltrimethoxysilane on the initial silica particles, an increased interaction between silica particles and the OLA/OLANa complex was achieved. This interaction between the oleyl and octadecyl chains resulted in the formation of stable gel-like aqueous systems. Subsequently, olive oil and an oleophylic red dye were solubilized in these stable aqueous systems. This great dispersing capacity of oleosoluble compounds opens new perspectives for future green chemistry applications. After the removal of water and of the organic chains by thermal treatment, mesoporous silica was obtained.

Preparation of carbon black masterbatch for PET using polymeric dispersing agents

Energy Technology Data Exchange (ETDEWEB)

Oh, D.H. [Kyungpook National University, Taegu (Korea, Republic of); Lim, J.C. [Pukyong National University, Pusan (Korea, Republic of); Seo, K.H. [Yeungnam College of Science and Technology, Taegu (Korea, Republic of)

1999-03-01

Three kinds of copolyesters, dispersing agents, were synthesized from the polycondensation reaction of dimethylterephthalate (DMT), dimethylisophthalate (DMI), sebacic acid (SA), and 1,4-butanediol (BD). Carbon black masterbatches were prepared by mixing carbon black into the dispersing agents (1 : 1.3 weight ratio) in a Brabender Plasticorder Using single screw extruder, masterbatches were compounded with poly(ethylene terephthalate) in 3 wt% concentration and mechanical properties of the compounds were investigated Gel permeation chromatography data implied that thermal degradation of polymeric dispersing agents was not significant through dispersion. Capillary rheometer test showed that PBTI has the highest viscosity and shear sensitivity among the there dispersing agents. Volume resistivities of masterbatch and transmission electron micrographs showed that dispersity of carbon black was improved with increasing melt viscosity of dispersing agent. The ultimate performance and mechanical characteristics of carbon black filled PET compounds depended directly on dispersion quality of the carbon black in masterbatch. Mechanical properties of compounds were improved with increasing dispersity of carbon black and with increasing content of rigid aromatic group in the copolyester dispersing agent. 30 refs., 9 figs., 5 tabs.

BisGMA/TEGDMA dental nanocomposites containing glyoxylic acid-modified high-aspect ratio hydroxyapatite nanofibers with enhanced dispersion

International Nuclear Information System (INIS)

Chen Liang; Yu Qingsong; Li Hao; Xu Changqi; Wang Yong; Shi Jian

2012-01-01

The purpose of this research was to investigate the influence of the glyoxylic acid (GA) modification of hydroxyapatite (HAP) nanofibers on their dispersion in bisphenol A glycidyl methacrylate (BisGMA)/triethylene glycol dimethacrylate (TEGDMA) dental composites and also to investigate the mechanical properties, water absorption and water solubility of the resulting dental resins and composites. Scanning/transmission electron microscopy images showed that microsized HAP nanofiber bundles could be effectively broken down into individual HAP nanofibers with an average length of ∼15 µm after the surface modification process. Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy and thermal gravimetric analysis characterization confirmed that GA was chemically grafted on the HAP nanofiber surface, hypothetically by reacting with the amine group on the HAP nanofiber surface. The enhanced dispersion of HAP nanofibers in the dental matrix led to increased biaxial flexural strength (BFS) compared with the corresponding dental resins and composites filled with untreated HAP nanofibers. In addition, impregnation of small mass fractions of the GA-modified HAP nanofibers into the BisGMA/TEGDMA dental resins (5 wt%, 10 wt%) or composites (2 wt%, 3 wt%) could also substantially improve the BFS in comparison with the controls (pure resins or dental composites filled with silica particles alone). Larger mass fractions could not increase the mechanical property further or even degraded the BFS values. Water behavior testing results indicated that the addition of the GA-modified HAP nanofibers resulted in higher water absorption and water solubility values, which are not preferred for clinical application. In summary, well-dispersed HAP nanofibers and their dental composites with enhanced mechanical properties have been successfully fabricated, but the water absorption and water solubility of such dental composites need to be further improved. (paper)

The Effects of Ammonium Polyacrylate and Diammonium Citrate as Base and Acid Dispersion Agents on Yttria-Stabilized Zirconia (3Y-TZP Dispersion Properties

Directory of Open Access Journals (Sweden)

Pestaria Sinaga

2018-01-01

Full Text Available Stable slurries in dispersions of 3Y-TZP in aqueous suspension with the addition of different concentrations of dispersants such as ammonium polyacrylate (APA and diammonium citrate (DAC were investigated. The dispersion properties were investigated by measuring the particle size, zeta potential, sedimentation, and viscosity as a function of the wt.% of the dispersant. Both dispersant agents were attached to the 3Y-TZP surface by the carboxylic group, as shown by the FTIR results. The addition of dispersants was found to produce more dispersed and stabilized aqueous suspension. As shown the viscosity result, that there is no being viscosity peak has been occurring and viscosity going decrease as the shear rates increasing which mean that the suspension has shear thinning behavior and there is no agglomeration as the shear rate is increased. It was determined that 3.5 wt.% of DAC and APA produced the best and most stable slurry; when 3.5 wt.% of DAC and APA was added, the zeta potential showed the largest value in the monodisperse condition. The low pH value of DAC has obtained the higher zeta potential value than APA, which was assumed due to low pH of DAC suspension. At low pH, the adsorption of the adsorbate will occur in a flat adsorbed, while at higher pH the polyelectrolyte will dangle into solution, thus reducing electrostatic repulsion as it is found in the case of APA addition. In this condition, the particle size was decreased to the lower value and the slurry’s stability was obtained with the lowest sedimentation height after the sedimentation test for 30 days. The sample was milled in an attrition mill at 1,000 rpm for four hours.

Effects of exchangeable Ca:Mg ratio on the dispersion of soils some ...

African Journals Online (AJOL)

The soils studied were acidic, low in nutrient level, showed high dispersion rate, high water- dispersible clay content and the textural class were loamy sand and sandy loam. The exchangeable Ca2+ and Mg2+ contents of the soils dominated the exchange complex. The cation exchange capacity (CEC) ranges between 4 ...

The Initial Comparison Study of Sodium Lignosulfonate, Sodium Dodecyl Benzene Sulfonate, and Sodium p-Toluene Sulfonate Surfactant for Enhanced Oil Recovery

Science.gov (United States)

Khoirul Anas, Argo; Iman Prakoso, Nurcahyo; Sasvita, Dilla

2018-04-01

Surfactant (surface active agent) exhibit numerous interesting properties that enable their use as additional component in mobilising of residual oil from capillary pore after secondary recovery process using gas injection and water flooding. In this study, Sodium Lignosulfonate (SLS) surfactant was successfully synthesized by applying batch method using lignin from oil palm empty fruit bunches as precursor. Furthermore, its performance in reducing interfacial tension of crude oil and formation water colloidal system was compared with commercial available surfactant including Sodium Dodecyl Benzene Sulfonate (SDBS) and Sodium p-Toluene Sulfonate (SpTS). The synthesized SLS surfactant was characterized by using Fourier Transform Infrared (FTIR) spectroscopy. Meanwhile, its performance in reducing interfacial tension of crude oil and formation water colloidal system was analyzed by using compatibility test, phase behaviour analysis, and interfacial tension (IFT) measurement. The compatibility test shows that SLS, SDBS, and SpTS surfactants were compatible with formation water. In addition, the phase behaviour analysis shows that SLS surfactant was better than SpTS surfactant, while SDBS surfactant generates the highest performance proved by the best microemulsion formation resulted by SDBS. Furthermore, the optimum concentration of SLS, SDBS, and SpTS surfactants in reducing the interfacial tension of crude oil and formation water was 1.0%. The IFT measurement indicates that the performance of SLS with the value of 1.67 mN/m was also better than SpTS surfactant with the value of 3.59 mN/m. Meanwhile, SDBS surfactant shows the best performance with the IFT value of 0.47 mN/m.

In Vitro assessment of dentin erosion after immersion in acidic beverages: surface profile analysis and energy-dispersive X-ray fluorescence spectrometry study

OpenAIRE

Caneppele, Taciana Marco Ferraz; Jeronymo, Raffaela Di Iorio; Di Nicoló, Rebeca; Araújo, Maria Amélia Máximo de; Soares, Luís Eduardo Silva

2012-01-01

The aim of this study was to investigate the effects of some acidic drinks on dentin erosion, using methods of surface profile (SP) analysis and energy-dispersive X-ray fluorescence spectrometry (EDXRF). One hundred standardized dentin slabs obtained from bovine incisor roots were used. Dentin slabs measuring 5x5 mm were ground flat, polished and half of each specimen surface was protected with nail polish. For 60 min, the dentin surfaces were immersed in 50 mL of 5 different drinks (Gatorade...

Sintesis Asam Etoksi Lignosulfonat sebagai Surfaktan dari Limbah Tandan Kosong Kelapa Sawit

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A Ardinal

2017-12-01

Full Text Available Synthesis of ethoxy lignosulfonic acid as a surfactant from a waste of palm oil empty fruit bunch was aimed to isolate lignin, studying the ethylation of the lignin and sulfonation of the alkyl lignin to produce ethoxy lignosulfonic acid moreover to investigate its activity as the surfactant. At first, lignin was isolated from the waste of palm oil empty fruit bunch by sulfate method, then lignin was alkylated with diethylsulfate (DES, and the resulted ethoxy lignin was sulfonated using sodium bisulfite. Each product was characterized by FT-IR and the success of the sulfonation was proven by SEM-EDX. Surfactant test properties included: determination of critical micelle concentration (CMC with turbidimetry method, foam stability, emulsions index and emulsion stability. Lignin isolation gave lignin as light brown solid in 27.8% yield. Alkylation reaction of lignin with diethyl sulfate produced ethoxy lignin in 83.0% yield. Sulfonation of ethoxy lignin using sodium bisulfite afforded ethoxy lignosulfonic acid in 88.5% yield. It was known that there was a significant increase in oxygen percentage at the sulfonation process. Ethoxy lignosulfonic acid as the surfactant has CMC of 1.6 g/L, the surfactant concentration of 1.5 g/L gave stable foam for 100 minutes, the surfactant has an emulsion index of 35% in a gasoline-water system and 56% in the cooking oil-water system. The emulsion on both systems was stable for four days of measurement.ABSTRAKSintesis asam etoksi lignosulfonat sebagai surfaktan dari limbah tandan kosong kelapa sawit (TKKS dilakukan dengan tujuan mengisolasi lignin dari TKKS, mempelajari etilasi terhadap lignin dan sulfonasi terhadap etoksi lignin untuk menghasilkan asam etoksi lignosulfonat serta uji aktifitasnya sebagai surfaktan. Lignin diisolasi dari TKKS dengan metode sulfat, lalu dialkilasi dengan dietil sulfat (DES dan disulfonasi dengan natrium bisulfit. Tiap produk dikarakterisasi dengan FT-IR dan untuk mengetahui

Method for the determination of carboxylic acids in industrial effluents using dispersive liquid-liquid microextraction with injection port derivatization gas chromatography-mass spectrometry.

Science.gov (United States)

Makoś, Patrycja; Fernandes, Andre; Boczkaj, Grzegorz

2017-09-29

The paper presents a new method for the determination of 15 carboxylic acids in samples of postoxidative effluents from the production of petroleum bitumens using ion-pair dispersive liquid-liquid microextraction and gas chromatography coupled to mass spectrometry with injection port derivatization. Several parameters related to the extraction and derivatization efficiency were optimized. Under optimized experimental conditions, the obtained limit of detection and quantification ranged from 0.0069 to 1.12μg/mL and 0.014 to 2.24μg/mL, respectively. The precision (RSD ranged 1.29-6.42%) and recovery (69.43-125.79%) were satisfactory. Nine carboxylic acids at concentrations ranging from 0.10μg/mL to 15.06μg/mL were determined in the raw wastewater and in samples of effluents treated by various oxidation methods. The studies revealed a substantial increase of concentration of benzoic acids, in samples of wastewater after treatment, which confirms the need of carboxylic acids monitoring during industrial effluent treatment processes. Copyright © 2017 Elsevier B.V. All rights reserved.

Low molecular weight compounds as effective dispersing agents in the formation of colloidal silver nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Natsuki, Jun; Natsuki, Toshiaki, E-mail: natsuki@shinshu-u.ac.jp; Abe, Takao [Shinshu University, Faculty of Textile Science and Technology (Japan)

2013-03-15

A convenient method to synthesize uniform, well-dispersed colloidal silver nanoparticles is described. Aldonic acid or {alpha}-hydroxy acid compounds of low molecular weight are used instead of polymeric compounds as dispersing agents to prepare silver nanoparticles. The size, conformation, and electrical conductivity of the silver nanoparticles, and the effect and function of the dispersing agents are investigated in detail. Using these low molecular weight compounds as dispersing agents, silver nanoparticles with a diameter of 10 nm or less and high electrical conductivity can be obtained. In addition, this procedure allows silver nanoparticles to be sintered at 150 Degree-Sign C, which is lower than that required for silver nanoparticle formulation using polymeric compounds (200 Degree-Sign C). The silver nanoparticles produced by this process can be used to prepare various inks and to manufacture electronic circuits. It is found that low molecular weight compounds are more effective dispersing agents than polymeric compounds in the formation of silver nanoparticles.

Dispersing surface-modified imogolite nanotubes in polar and non-polar solvents

Science.gov (United States)

Li, Ming; Brant, Jonathan A.

2018-02-01

Furthering the development of nanocomposite structures, namely membranes for water treatment applications, requires that methods be developed to ensure nanoparticle dispersion in polar and non-polar solvents, as both are widely used in associated synthesis techniques. Here, we report on a two-step method to graft polyvinylpyrrolidone (PVP), and a one-step method for octadecylphosphonic acid (OPA), onto the outer surfaces of imogolite nanotubes. The goal of these approaches was to improve and maintain nanotube dispersion in polymer compatible polar and non-polar solvents. The PVP coating modified the imogolite surface charge from positive to weakly negative at pH ≤ 9; the OPA made it weakly positive at acidic pH values to negative at pH ≥ 7. The PVP surface coating stabilized the nanotubes through steric hindrance in polar protic, dipolar aprotic, and chloroform. In difference to the PVP, the OPA surface coating allowed the nanotubes to be dispersed in n-hexane and chloroform, but not in the polar solvents. The lack of miscibility in the polar solvents, as well as the better dispersion in n-hexane, was attributed to the stronger hydrophobicity of the OPA polymer relative to the PVP. [Figure not available: see fulltext.

Development of novel sibutramine base-loaded solid dispersion with gelatin and HPMC: physicochemical characterization and pharmacokinetics in beagle dogs.

Science.gov (United States)

Lim, Hyun-Tae; Balakrishnan, Prabagar; Oh, Dong Hoon; Joe, Kwan Hyung; Kim, Young Ran; Hwang, Doo Hyung; Lee, Yong-Bok; Yong, Chul Soon; Choi, Han-Gon

2010-09-15

To develop a novel sibutramine base-loaded solid dispersion with enhanced solubility and bioavailability, various solid dispersions were prepared using a spray drying technique with hydrophilic polymers such as gelatin, HPMC and citric acid. Their solubility, thermal characteristics and crystallinity were investigated. The dissolution and pharmacokinetics of the sibutramine base-loaded solid dispersion were then compared with a sibutramine hydrochloride monohydrate-loaded commercial product (Reductil). The solid dispersions prepared with gelatin gave higher drug solubility than those prepared without gelatin, irrespective of the amount of polymer. The sibutramine base-loaded solid dispersions containing hydrophilic polymer and citric acid showed higher drug solubility compared to sibutramine base and sibutramine hydrochloride monohydrate. Among the formulations tested, the solid dispersion composed of sibutramine base/gelatin/HPMC/citric acid at the weight ratio of 1/0.8/0.2/0.5 gave the highest solubility of 5.03+/-0.24 mg/ml. Our DSC and powder X-ray diffraction results showed that the drug was present in an altered amorphous form in this solid dispersion. The difference factor (f(1)) values between solid dispersion and commercial product were 2.82, 6.65 and 6.31 at pH 1.2, 4.0 and 6.8, respectively. Furthermore, they had the similarity factor (f(2)) value of 65.68, 53.43 and 58.97 at pH 1.2, 4.0 and 6.8, respectively. Our results suggested that the solid dispersion and commercial product produced a similar correlation of dissolution profiles at all pH ranges. The AUC, C(max) and T(max) of the parent drug and metabolite I and II from the solid dispersion were not significantly different from those of the commercial product, suggesting that the solid dispersion might be bioequivalent to the commercial product in beagle dogs. Thus, the sibutramine base-loaded solid dispersion prepared with gelatin, HPMC and citric acid is a promising candidate for improving the

Solid lipid dispersions: potential delivery system for functional ingredients in foods.

Science.gov (United States)

Asumadu-Mensah, Aboagyewa; Smith, Kevin W; Ribeiro, Henelyta S

2013-07-01

Structured solid lipid (SL) systems have the advantages of long-term physical stability, low surfactant concentrations, and may exhibit controlled release of active ingredients. In this research work, the potential use of high-melting SLs for the production of the above structured SL carrier systems was investigated. Dispersions containing either SL or blend of solid lipid and oil (SL+O) were produced by a hot melt high-pressure homogenization method. Experiments involved the use of 3 different SLs for the disperse phase: stearic acid, candelilla wax and carnauba wax. Sunflower oil was incorporated in the disperse phase for the production of the dispersions containing lipid and oil. In order to evaluate the practical aspects of structured particles, analytical techniques were used including: static light scattering to measure particle sizes, transmission electron microscopy (TEM) for investigating particle morphology and differential scanning calorimetry (DSC) to investigate the crystallization behavior of lipids in bulk and in dispersions. Results showed different mean particle sizes depending on the type of lipid used in the disperse phase. Particle sizes for the 3 lipids were: stearic acid (SL: 195 ± 2.5 nm; SL+O: 138 ± 6.0 nm); candelilla wax (SL: 178 ± 1.7 nm; SL+O: 144 ± 0.6 nm); carnauba wax (SL: 303 ± 1.5 nm; SL+O: 295 ± 5.0 nm). TEM results gave an insight into the practical morphology, showing plate-like and needle-like structures. DSC investigations also revealed that SL dispersions melted and crystallized at lower temperatures than the bulk. This decrease can be explained by the small particle sizes of the dispersion, the high-specific surface area, and the presence of a surfactant. © 2013 Institute of Food Technologists®

Aqueous Dispersions of Silica Stabilized with Oleic Acid Obtained by Green Chemistry

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Cristina Lavinia Nistor

2016-01-01

Full Text Available The present study describes for the first time the synthesis of silica nanoparticles starting from sodium silicate and oleic acid (OLA. The interactions between OLA and sodium silicate require an optimal OLA/OLANa molar ratio able to generate vesicles that can stabilize silica particles obtained by the sol-gel process of sodium silicate. The optimal molar ratio of OLA/OLANa can be ensured by a proper selection of OLA and respectively of sodium silicate concentration. The titration of sodium silicate with OLA revealed a stabilization phenomenon of silica/OLA vesicles and the dependence between their average size and reagent’s molar ratio. Dynamic light scattering (DLS and scanning electron microscopy (SEM measurements emphasized the successful synthesis of silica nanoparticles starting from renewable materials, in mild condition of green chemistry. By grafting octadecyltrimethoxysilane on the initial silica particles, an increased interaction between silica particles and the OLA/OLANa complex was achieved. This interaction between the oleyl and octadecyl chains resulted in the formation of stable gel-like aqueous systems. Subsequently, olive oil and an oleophylic red dye were solubilized in these stable aqueous systems. This great dispersing capacity of oleosoluble compounds opens new perspectives for future green chemistry applications. After the removal of water and of the organic chains by thermal treatment, mesoporous silica was obtained.

A New Multichelating Acid System for High-Temperature Sandstone Reservoirs

Directory of Open Access Journals (Sweden)

Nianyin Li

2015-01-01

Full Text Available Sandstone reservoir acidizing is a complex and heterogeneous acid-rock reaction process. If improper acid treatment is implemented, further damage can be induced instead of removing the initial plug, particularly in high-temperature sandstone reservoirs. An efficient acid system is the key to successful acid treatment. High-temperature sandstone treatment with conventional mud acid system faces problems including high acid-rock reaction rate, short acid effective distance, susceptibility to secondary damage, and serious corrosion to pipelines. In this paper, a new multichelating acid system has been developed to overcome these shortcomings. The acid system is composed of ternary weak acid, organic phosphonic chelating agent, anionic polycarboxylic acid chelating dispersant, fluoride, and other assisted additives. Hydrogen ion slowly released by multistage ionization in ternary weak acid and organic phosphonic within the system decreases the concentration of HF to achieve retardation. Chelating agent and chelating dispersant within the system inhibited anodic and cathodic reaction, respectively, to protect the metal from corrosion, while chelating dispersant has great chelating ability on iron ions, restricting the depolarization reaction of ferric ion and metal. The synergic effect of chelating agent and chelating dispersant removes sulfate scale precipitation and inhibits or decreases potential precipitation such as CaF2, silica gel, and fluosilicate. Mechanisms of retardation, corrosion-inhibition, and scale-removing features have been discussed and evaluated with laboratory tests. Test results indicate that this novel acid system has good overall performance, addressing the technical problems and improving the acidizing effect as well for high-temperature sandstone.

Polymeric dispersants for control of steam generator fouling

International Nuclear Information System (INIS)

Balakrishnan, P.V.; Klimas, S.J.; Lepine, L.; Turner, C.W.

1999-05-01

Fouling of steam generators by corrosion products from the feedtrain leads to loss of heat-transfer efficiency, disturbances in thermalhydraulics, and potential corrosion problems resulting from the development of sites for localized accumulation of aggressive chemicals. This report summarizes studies of the use of polymeric dispersants for the control of fouling, which were conducted at the Chalk River Laboratories. High-temperature settling studies on magnetite suspensions were performed to screen available generic dispersants, and the dispersants were ranked in terms of their dispersion efficiency; polyacrylic acid (PAA) and the phosphonate, HEDP, were ranked as the most efficient. Polyacrylic acid was considered more suitable than HEDP for nuclear steam generators, and more emphasis was given to the former in these studies. The dispersants had no effect on the particle deposition rates under single-phase forced-convective flow, but did reduce the deposition rates under flow-boiling conditions. The extent to which the deposition rates were reduced increased in proportion to the dispersant concentration. Preliminary corrosion tests indicated that pitting or general corrosion of steam generator tube materials in the presence of PAA was negligible. Corrosion of carbon steel, although higher in a magnetite-packed crevice under heat flux than in bulk water, was lower in the presence of PAA than in its absence. Some impurities (e.g., sulphate, sodium) were observed in commercially available PAA products at small, though significant concentrations, making these products unacceptable for use in nuclear plants. However, the PAA could be purified by ion exchange. Preliminary experiments, to assess the thermal stability of PAA at steam generator operating temperature, showed the polymer to break down in deaerated solutions and under argon cover to give hydrogen and carbon dioxide as the two major products in the gas phase and variable concentrations of acetate and formate

Acidizing reservoirs while chelating iron with sulfosalicylic acid

Energy Technology Data Exchange (ETDEWEB)

McLaughlin, W A; Berkshire, D C

1980-09-30

A well treating process is described in which an aqueous solution of a strong acid capable of dissolving solids in a manner increasing the permeability of a subterranean earth formation is injected into a subterranean reservoir that contains an asphaltenic oil. At least the first injected portion of the aqueous acid and a solution or homogeneous dispersion of at least enough 5-sulfosalicylic acid to chelate with and prevent the formation of iron-asphaltene solids are included with substantially all of the ferric ions that become dissolved within the strong acid solution that enters the earth formation. 10 claims.

Translational and rotational diffusion of flexible PEG and rigid dendrimer probes in sodium caseinate dispersions and acid gels.

Science.gov (United States)

Salami, Souad; Rondeau-Mouro, Corinne; Barhoum, Myriam; van Duynhoven, John; Mariette, François

2014-09-01

The dynamics of rigid dendrimer and flexible PEG probes in sodium caseinate dispersions and acid gels, including both translational diffusion and rotational diffusion, were studied by NMR. Above the onset of the close-packing limit (C ∼ 10 g/100 g H2 O), translational diffusion of the probe depended on its flexibility and on the fluctuations of the matrix chains. The PEG probe diffused more rapidly than the spherical dendrimer probe of corresponding hydrodynamic radius. The greater conformational flexibility of PEG facilitated its motion through the crowded casein matrix. Rotational diffusion was, however, substantially less hindered than the translational diffusion and depended on the local protein-probe friction which became high when the casein concentration increased. The coagulation of the matrix led to the formation of large voids, which resulted in an increase in the translational diffusion of the probes, whereas the rotational diffusion of the probes was retarded in the gel, which could be attributed to the immobilized environment surrounding the probe. Quantitative information from PFG-NMR and SEM micrographs have been combined for characterizing microstructural details in SC acid gels. © 2014 Wiley Periodicals, Inc.

Milling and dispersion of multi-walled carbon nanotubes in texanol

Science.gov (United States)

Darsono, Nono; Yoon, Dang-Hyok; Kim, Jaemyung

2008-03-01

Rheological results were used to determine the optimum type of dispersant and its concentration for six commercial dispersants for the dispersion of multi-walled carbon nanotube (MWCNT) agglomerates in texanol. An unsaturated polycarboxylic acid copolymer (BYK P-104) exhibited the optimum performance with the lowest MWCNT slurry viscosity in texanol. The cutting and dispersion efficiencies of MWCNTs with 20 wt.% of BYK P-104 dispersant were compared using conventional ball milling and high energy milling, whereby the latter was found to be more effective. High energy milling for 2 h produced a large portion of MWCNT agglomerates smaller than 150 nm, showing a drastic increase in slurry viscosity due to the dispersion into individual CNTs. On the other hand, 120 h ball milling was required to achieve the agglomerate size of 300 nm with less viscosity increase upon milling. Decrease in the degree of MWCNT crystallinity was observed by both milling, even though 2 h high energy milling showed slightly less damage than 120 h ball milling based on XRD and Raman spectroscopy results.

Profiling the Fatty Acids Content of Ornamental Camellia Seeds Cultivated in Galicia by an Optimized Matrix Solid-Phase Dispersion Extraction

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Carmen Garcia-Jares

2017-10-01

Full Text Available Camellia (genus of flowering plants of fam. Theaceae is one of the main crops in Asia, where tea and oil from leaves and seeds have been utilized for thousands of years. This plant is excellently adapted to the climate and soil of Galicia (northwestern Spain and northern Portugal where it is grown not only as an ornamental plant, but to be evaluated as a source of bioactive compounds. In this work, the main fatty acids were extracted from Camellia seeds of four varieties of Camellia: sasanqua, reticulata, japonica and sinensis, by means of matrix-solid phase dispersion (MSPD, and analyzed by gas chromatography (GC with MS detection of the corresponding methyl esters. MSPD constitutes an efficient and greener alternative to conventional extraction techniques, moreover if it is combined with the use of green solvents such as limonene. The optimization of the MSPD extraction procedure has been conducted using a multivariate approach based on strategies of experimental design, which enabled the simultaneous evaluation of the factors influencing the extraction efficiency as well as interactions between factors. The optimized method was applied to characterize the fatty acids profiles of four Camellia varieties seeds, allowing us to compare their fatty acid composition.

Profiling the Fatty Acids Content of Ornamental Camellia Seeds Cultivated in Galicia by an Optimized Matrix Solid-Phase Dispersion Extraction

Science.gov (United States)

Garcia-Jares, Carmen; Sanchez-Nande, Marta; Lamas, Juan Pablo; Lores, Marta

2017-01-01

Camellia (genus of flowering plants of fam. Theaceae) is one of the main crops in Asia, where tea and oil from leaves and seeds have been utilized for thousands of years. This plant is excellently adapted to the climate and soil of Galicia (northwestern Spain) and northern Portugal where it is grown not only as an ornamental plant, but to be evaluated as a source of bioactive compounds. In this work, the main fatty acids were extracted from Camellia seeds of four varieties of Camellia: sasanqua, reticulata, japonica and sinensis, by means of matrix-solid phase dispersion (MSPD), and analyzed by gas chromatography (GC) with MS detection of the corresponding methyl esters. MSPD constitutes an efficient and greener alternative to conventional extraction techniques, moreover if it is combined with the use of green solvents such as limonene. The optimization of the MSPD extraction procedure has been conducted using a multivariate approach based on strategies of experimental design, which enabled the simultaneous evaluation of the factors influencing the extraction efficiency as well as interactions between factors. The optimized method was applied to characterize the fatty acids profiles of four Camellia varieties seeds, allowing us to compare their fatty acid composition. PMID:29039745

Effects of ionizing radiation on the peroxide content of a pure polyunsaturated lipid dispersion and of lipids and membranes derived from Acholeplasma laidlawii

Energy Technology Data Exchange (ETDEWEB)

Edwards, J.C.; Cramp, W.A. (Hammersmith Hospital, London (UK). M.R.C. Cyclotron Unit); Chapman, D. (Royal Free Hospital, London (UK))

1984-01-01

Dispersions of a pure unsaturated phospholipid, dilinoleoylphosphatidyl choline, formed conjugated diene hydroperoxides when irradiated in air with 7 MeV electrons (150 Gy and 300 Gy). Peroxide formation was optimized when the dispersions were irradiated in air at 37/sup 0/C at a dose rate of 5 Gy/min. No significant loss of linoleic acid from the irradiated phospholipid dispersions was observed after doses of 150 or 300 Gy. Small amounts of thiobarbituric acid-reactive material were formed in irradiated unsaturated phospholipid dispersions. However, lipids or membranes isolated from 48 hour cultures of Acholeplasma laidlawii grown in media supplemented with either linoleic or linolenic acid did not appear to be peroxidized by irradiation under the same conditions.

Dispersal of micro-organisms in commercial defeathering systems.

Science.gov (United States)

Allen, V M; Tinker, D B; Hinton, M H; Wathes, C M

2003-03-01

1. The extent of cross contamination between carcases and the dispersal of micro-organisms to the environs during defeathering was measured in a commercial processing plant. 2. Defeathering reduced the numbers of a marker organism, a nalidixic acid-resistant strain of Escherichia coli K12, on inoculated carcases but dispersed the organism on to preceding and following carcases. 3. The pattern of microbial dispersal during defeathering was similar for naturally occurring bacteria on the carcase, for example, total aerobic counts and counts of presumptive coliforms, suggesting that the marker organism mimics the natural situation realistically. 4. The majority of feathers, together with micro-organisms, were removed during the first 10 s of the defeathering process, which was completed in 45 s, indicating that control measures to minimise cross contamination would be most effective if applied in the early stages of the process. 5. The method of defeathering used by the machine influenced the pattern of microbial dispersal and the extent of cross contamination to other carcases on the same processing line.

Purification and Partial characterization of manganese peroxidase from Bacillus pumilus AND Paenibacillus sp.

Directory of Open Access Journals (Sweden)

Patrícia Lopes de Oliveira

2009-12-01

Full Text Available The production of manganese peroxidase (MnP from Bacillus pumilus and Paenibacillus sp. was studied under absence and presence of the inducers indulin AT, guayacol, veratryl alcohol, lignosulfonic acid and lignosulfonic acid desulfonated. Indulin AT increased the activity of B. pumilus MnP up to 31.66 U/L after 8 h, but no improve was observed for Paenibacillus sp., which reached maximum activity (12.22 U/L after 20 h. Both MnPs produced by these microorganisms were purified in phenyl sepharose resin and the proteins from crude extracts were eluted in two fractions. However, only the first fraction of each extract exhibited MnP activities. Tests in different pH and temperature values, from pH 5.0 to pH 10.0 and 30 ºC to 60 ºC, respectively, were carried out with the purified MnP. The maximum activity reached for B. pumilus and Paenibacillus sp. MnPs were 4.3 U/L at pH 8.0 and 25 ºC and 11.74 U/L at pH 9.0 and 35 ºC, respectively. The molar masses determined by SDS-PAGE gel eletrophoresis were 25 kDa and 40 kDa, respectively, for the purified enzyme from B. pumilus and Paenibacillus sp.

Preparation of amorphous solid dispersions by rotary evaporation and KinetiSol Dispersing: approaches to enhance solubility of a poorly water-soluble gum extract.

Science.gov (United States)

Bennett, Ryan C; Brough, Chris; Miller, Dave A; O'Donnell, Kevin P; Keen, Justin M; Hughey, Justin R; Williams, Robert O; McGinity, James W

2015-03-01

Acetyl-11-keto-β-boswellic acid (AKBA), a gum resin extract, possesses poor water-solubility that limits bioavailability and a high melting point making it difficult to successfully process into solid dispersions by fusion methods. The purpose of this study was to investigate solvent and thermal processing techniques for the preparation of amorphous solid dispersions (ASDs) exhibiting enhanced solubility, dissolution rates and bioavailability. Solid dispersions were successfully produced by rotary evaporation (RE) and KinetiSol® Dispersing (KSD). Solid state and chemical characterization revealed that ASD with good potency and purity were produced by both RE and KSD. Results of the RE studies demonstrated that AQOAT®-LF, AQOAT®-MF, Eudragit® L100-55 and Soluplus with the incorporation of dioctyl sulfosuccinate sodium provided substantial solubility enhancement. Non-sink dissolution analysis showed enhanced dissolution properties for KSD-processed solid dispersions in comparison to RE-processed solid dispersions. Variances in release performance were identified when different particle size fractions of KSD samples were analyzed. Selected RE samples varying in particle surface morphologies were placed under storage and exhibited crystalline growth following solid-state stability analysis at 12 months in comparison to stored KSD samples confirming amorphous instability for RE products. In vivo analysis of KSD-processed solid dispersions revealed significantly enhanced AKBA absorption in comparison to the neat, active substance.

A Crew Exposure Study. Volume I. Offshore.

Science.gov (United States)

1982-03-15

Calcium Lignosulfonate D. Lime E. Salt F. Ammonium Acid Phosphate, (NH4)2 HPO4 IX. Filtrate Reducers A. Asphalt Emulsion B. Guar Gum C. HEC (Hydroxyethyl...Tetraphosphate 4. Caustic and Quebracho (sodium tannate) II. Thickening Agents A. Asbestos B. Xanthan Gum . III. Viscosifiers A. Bentonite 1. Sodium...Wood VII. Lubricants A. Oils B. Graphite Powder C. Soaps D. Sodium Sulfonate Asphalt VIII. Shale Control Inhibitors A. Gypsum B. Sodium Silicate C

Re-dispersion of alumina particles in water: influence of the surface state

International Nuclear Information System (INIS)

Desset, Sabine

1999-01-01

The aim of this work was to determine the mechanisms by which suspensions of alpha alumina particles may be dried and then re-dispersed spontaneously in water. To get reproducible results, we designed appropriate protocols: (i) for preparing the surface state, and for generating controlled interparticle contacts (presence of water or complexing agents); (ii) for measuring the amount of re-dispersed material with a proper averaging over all interparticle bonds (turbidity). These results show that there are thresholds, determined by the conditions of drying and re-dispersion, where all the powder goes from the aggregated state to the dispersed state. With hydrated powders, it was found that mild changes in the chemical conditions (pH) and application of very weak mechanical forces (sedimentation) were enough to cause significant change in re-dispersion. According to these thresholds, a re-dispersion mechanism could be identified. Re-dispersion is ruled, indeed, by a balance of forces and the displacement of the re-dispersion thresholds indicates a shift in the balance of forces. These forces are the well known forces that control colloidal stability: van der Waals attraction, electrostatic repulsion and hydration forces. We found that hydration acts as a repulsive wall corresponding to one or two monolayers of water on each surface and depends on the Relative Humidity of drying. We also found that electrostatic repulsions at short separations are much weaker than the predictions based on the Poisson Boltzmann equation, but should be modelled according to the triple layer model. Repulsions to be considered are those calculated with the screened charges of the particles. Another aim of this work was to facilitate re-dispersion by using complexing agents that bind to the surfaces and add a steric repulsion We have found that molecules with carboxylic and hydroxyl groups can be efficient in this respect, if they are bound to surfaces before aggregation, if they are not

Re-dispersion of alumina particles in water: influence of the surface state

International Nuclear Information System (INIS)

Desset, Sabine

1999-01-01

The aim of this work was to determine the mechanisms by which suspensions of alpha alumina particles may be dried and then re-dispersed spontaneously in water. To get reproducible results, we designed appropriate protocols: (i) for preparing the surface state, and for generating controlled interparticle contacts (presence of water or complexing agents); (ii) for measuring the amount of re-dispersed material with a proper averaging over all interparticle bonds (turbidity). These results show that there are thresholds, determined by the conditions of drying and re-dispersion, where all the powder goes from the aggregated state to the dispersed state. With hydrated powders, it was found that mild changes in the chemical conditions (pH) and application of very weak mechanical forces (sedimentation) were enough to cause significant change in re-dispersion. According to these thresholds, a re-dispersion mechanism could be identified. Re-dispersion is ruled, indeed, by a balance of forces and the displacement of the re-dispersion thresholds indicates a shift in the balance of forces. These forces are the well-known forces that control colloidal stability: van der Waals attraction, electrostatic repulsion and hydration forces. We found that hydration acts as a repulsive wall corresponding to one or two monolayers of water on each surface and depends on the Relative Humidity of drying. We also found that electrostatic repulsions at short separations are much weaker than the predictions based on the Poisson Boltzmann equation, but should be modelled according to the triple layer model. Repulsions to be considered are those calculated with the screened charges of the particles. Another aim of this work was to facilitate re-dispersion by using complexing agents that bind to the surfaces and add a steric repulsion We have found that molecules with carboxylic and hydroxyl groups can be efficient in this respect, if they are bound to surfaces before aggregation, if they are not

Colloidal approach to dispersion and enhanced deaggregation of aqueous ferrite suspensions

Science.gov (United States)

Mandanas, Michael Patrick M.

The role of solution and surface chemistry on deaggregation of calcined ferrites during attrition (stirred-media) milling of aqueous suspensions were investigated. Suspensions of commercially calcined Fe2O 3 powder (d50 ˜ 5.0 mum) were milled at different solid loadings and suspension pH. The drift of suspension pH, from pH 2.5 to pH 7.0, during solid loading experiments accounted for the observed reagglomeration with milling time. The observed deaggregation rates during pH stat milling, in the acidic region, can be related to (i) elevated solubility and (ii) enhanced dispersion via surface charge. Proton adsorption density during pH stat milling at different pH values is also comparable to existing potentiometric titration plots and can be related to deaggregation rates. A passivation-dispersion approach for dispersing manganese zinc ferrite (MnxZn(1 - x)Fe2O4) powder is presented. Addition of oxalic acid can help control dissolution reactions from particle surfaces and is subsequently dispersed with polyethyleneimine (PEI). Fully dissociated oxalic acid (pK1 = 1.2, pK2 = 4.3) solutions reacted with MnxZn(1 - x)Fe 2O4 leads to the formation of a uniform negative charge on the particle surface, resulting from the sparingly soluble salt formed on the surface. The resulting rheological data for passivation/dispersion of relatively high solid MnxZn(1 - x)Fe2O 4 suspensions (˜80 w/o, (˜40 v/o)) demonstrate improved colloid stability with improved rheological properties. Using the passivation dispersion scheme developed, deaggregation of commercially calcined MnxZn(1 - x)Fe2O4 powders during attrition milling was investigated. Reagglomeration is apparent when using a typical treatment, 2 w/w of a sulfonated based naphthalene condensate, during deaggregation of the calcined MnxZn(1 - x)Fe 2O4. However, is not observed for select oxalate/PEI treatments. The determined ideal treatment is 2 w/w oxalate and 3 w/w PEI based on the particle size and rheological

Determination of plutonium in nitric acid solutions using energy dispersive L X-ray fluorescence with a low power X-ray generator

Energy Technology Data Exchange (ETDEWEB)

Py, J. [Laboratoire Chrono-Environnement, UMR CNRS 6249, Université de Franche-Comté, 16 route de Gray, F-25030 Besançon (France); Commissariat à l’Énergie Atomique, Centre de Valduc, F-21120 Is-sur-Tille (France); Groetz, J.-E., E-mail: jegroetz@univ-fcomte.fr [Laboratoire Chrono-Environnement, UMR CNRS 6249, Université de Franche-Comté, 16 route de Gray, F-25030 Besançon (France); Hubinois, J.-C.; Cardona, D. [Commissariat à l’Énergie Atomique, Centre de Valduc, F-21120 Is-sur-Tille (France)

2015-04-21

This work presents the development of an in-line energy dispersive L X-ray fluorescence spectrometer set-up, with a low power X-ray generator and a secondary target, for the determination of plutonium concentration in nitric acid solutions. The intensity of the L X-rays from the internal conversion and gamma rays emitted by the daughter nuclei from plutonium is minimized and corrected, in order to eliminate the interferences with the L X-ray fluorescence spectrum. The matrix effects are then corrected by the Compton peak method. A calibration plot for plutonium solutions within the range 0.1–20 g L{sup −1} is given.

Oxidative Stability of Dispersions Prepared from Purified Marine Phospholipid and the Role of α-Tocopherol

DEFF Research Database (Denmark)

Lu, Henna Fung Sieng; Nielsen, Nina Skall; Baron, Caroline P.

2012-01-01

, respectively, during 32 days of storage at 2 °C. Nonenzymatic browning was investigated through measurement of Strecker aldehydes, color changes, and pyrrole content. Dispersions containing α-tocopherol or higher levels of purified marine PL showed a lower increment of volatiles after 32 days storage......The objective of this study was to investigate the oxidative stability of dispersions prepared from different levels of purified marine phospholipid (PL) obtained by acetone precipitation, with particular focus on the interaction between α-tocopherol and PL in dispersions. This also included...... the investigation of nonenzymatic browning in purified marine PL dispersions. Dispersions were prepared by high-pressure homogenizer. The oxidative and hydrolytic stabilities of dispersions were investigated by determination of hydroperoxides, secondary volatile oxidation products, and free fatty acids...

Water-Dispersible Multi-Walled Carbon Nanotubes and Novel Hybrid Nanostructures

NARCIS (Netherlands)

Pham, Tuan Anh; Son, Se Mo; Jeong, Yeon Tae

2010-01-01

Water-dispersible multi-walled carbon nanotubes (MWNTs) were successfully prepared by the chemical grafting of acylated MWNTs with adenosine. The MWNTs were first purified and oxidized in order to obtain carboxylic acid funcionalized MWNTs, which was further acylated with thionyl chloride to give

Dispersability of Carbon Nanotubes in Biopolymer-Based Fluids

Directory of Open Access Journals (Sweden)

Franco Tardani

2015-01-01

Full Text Available In this review the dispersability of carbon nanotubes in aqueous solutions containing proteins, or nucleic acids, is discussed. Data reported previously are complemented by unpublished ones. In the mentioned nanotube-based systems several different phases are observed, depending on the type and concentration of biopolymer, as well as the amount of dispersed nanotubes. The phase behavior depends on how much biopolymers are adsorbing, and, naturally, on the molecular details of the adsorbents. Proper modulation of nanotube/biopolymer interactions helps switching between repulsive and attractive regimes. Dispersion or phase separation take place, respectively, and the formation of liquid crystalline phases or gels may prevail with respect to dispersions. We report on systems containing ss-DNA- and lysozyme-stabilized nanotubes, representative of different organization modes. In the former case, ss-DNA rolls around CNTs and ensures complete coverage. Conversely, proteins randomly and non-cooperatively adsorb onto nanotubes. The two functionalization mechanisms are significantly different. A fine-tuning of temperature, added polymer, pH, and/or ionic strength conditions induces the formation of a given supra-molecular organization mode. The biopolymer physico-chemical properties are relevant to induce the formation of different phases made of carbon nanotubes.

End Functionalized Nonionic Water-Dispersible Conjugated Polymers.

Science.gov (United States)

Zhan, Ruoyu; Liu, Bin

2017-09-01

2,7-Dibromofluorene monomers carrying two or four oligo(ethylene glycol) (OEG) side chains are synthesized. Heck coupling between the monomers and 1,4-divinylbenzene followed by end capping with [4-(4-bromophenoxy)butyl]carbamic acid tert-butyl ester leads to two nonionic water-dispersible poly(fluorene-alt-1,4-divinylenephenylene)s end-functionalized with amine groups after hydrolysis. In water, the polymer with a lower OEG density (P1) has poor water dispersibility with a quantum yield of 0.24, while the polymer with a higher OEG density (P2) possesses excellent water-dispersibility with a high quantum yield of 0.45. Both polymers show fluorescence enhancement and blue-shifted absorption and emission maxima in the presence of surfactant sodium dodecyl sulfate and dodecyltrimethylammonium bromide. The polymers are also resistant to ionic strength with minimal nonspecific interactions to bovine serum albumin. When biotin is incorporated into the end of the polymer backbones through N-hydroxysuccinimide/amine coupling reaction, the biotinylated polymers interact specifically with streptavidin on solid surface. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Extraction and Determination of Ellagic Acid Content in the Peels of Six Iranian Pomegranates Cultivars Using a New Miniaturized Matrix Solid-Phase Dispersion Method

Directory of Open Access Journals (Sweden)

Fariba Nazari Serenjeh

2017-03-01

Full Text Available Background and Aim:The peels of six Iranian pomegranates (Punica granatum L. cultivars, as a traditional medicine, were treated with a new miniaturized matrix solid-phase dispersion (MSPD method for the HPLC determination of ellagic acid (EA. Materials and Methods:In the proposed method, only 10mg of the sample powder was ground and blended with an equal amount of C18 sorbent in an agate mortar. The use of the agate mortar with smooth surface facilitated the sample transfer into a cartridge and reduced the required amount of sample and sorbent. Micro volumes of dichloromethane, n-hexane and methanol were used as modifier, washing and elution solvents, respectively. The eluate was injected into an HPLC-UV system for the analysis. Results:Several factors such as the type and amount of dispersing sorbent, modifier, washing solvent and eluent were carefully studied and optimized. Six replicated analyses at the optimized conditions resulted in a recovery of 96.7% and a relative standard deviation of 5.87%. The proposed method was successfully applied to the extraction and determination of EA in the peels samples. Conclusion:According to the ultimate results, the MSPD method is an efficient technique for the quantitative extraction of EA from the peels of pomegranate. Malas cultivar has the highest amount (18.1 g kg-1 of ellagic acid content compared to the other studied pomegranate cultivars.

In vitro activity of the new water-dispersible Fe3O4@usnic acid nanostructure against planktonic and sessile bacterial cells

Science.gov (United States)

Grumezescu, Alexandru Mihai; Cotar, Ani Ioana; Andronescu, Ecaterina; Ficai, Anton; Ghitulica, Cristina Daniela; Grumezescu, Valentina; Vasile, Bogdan Stefan; Chifiriuc, Mariana Carmen

2013-07-01

A new water-dispersible nanostructure based on magnetite (Fe3O4) and usnic acid (UA) was prepared in a well-shaped spherical form by a precipitation method. Nanoparticles were well individualized and homogeneous in size. The presence of Fe3O4@UA was confirmed by transmission electron microscopy, Fourier transform-infrared spectroscopy, and X-ray diffraction. The UA was entrapped in the magnetic nanoparticles during preparation and the amount of entrapped UA was estimated by thermogravimetric analysis. Fabricated nanostructures were tested on planktonic cells growth (minimal inhibitory concentration assay) and biofilm development on Gram-positive Staphylococcus aureus ( S. aureus), Enterococcus faecalis ( E. faecalis) and Gram-negative Escherichia coli ( E. coli), Pseudomonas aeruginosa (P. aeruginosa) reference strains. Concerning the influence of Fe3O4@UA on the planktonic bacterial cells, the functionalized magnetic nanoparticles exhibited a significantly improved antimicrobial activity against E. faecalis and E. coli, as compared with the Fe3O4 control. The UA incorporated into the magnetic nanoparticles exhibited a very significant inhibitory effect on the biofilm formed by the S. aureus and E. faecalis, on a wide range of concentrations, while in case of the Gram-negative microbial strains, the UA-loaded nanoparticles inhibited the E. coli biofilm development, only at high concentrations, while for P. aeruginosa biofilms, no inhibitory effect was observed. The obtained results demonstrate that the new water-dispersible Fe3O4@UA nanosystem, combining the advantages of the intrinsic antimicrobial features of the UA with the higher surface to volume ratio provided by the magnetic nanocarrier dispersible in water, exhibits efficient antimicrobial activity against planktonic and adherent cells, especially on Gram-positive strains.

In vitro activity of the new water-dispersible Fe3O4@usnic acid nanostructure against planktonic and sessile bacterial cells

International Nuclear Information System (INIS)

Grumezescu, Alexandru Mihai; Cotar, Ani Ioana; Andronescu, Ecaterina; Ficai, Anton; Ghitulica, Cristina Daniela; Grumezescu, Valentina; Vasile, Bogdan Stefan; Chifiriuc, Mariana Carmen

2013-01-01

A new water-dispersible nanostructure based on magnetite (Fe 3 O 4 ) and usnic acid (UA) was prepared in a well-shaped spherical form by a precipitation method. Nanoparticles were well individualized and homogeneous in size. The presence of Fe 3 O 4 @UA was confirmed by transmission electron microscopy, Fourier transform-infrared spectroscopy, and X-ray diffraction. The UA was entrapped in the magnetic nanoparticles during preparation and the amount of entrapped UA was estimated by thermogravimetric analysis. Fabricated nanostructures were tested on planktonic cells growth (minimal inhibitory concentration assay) and biofilm development on Gram-positive Staphylococcusaureus (S.aureus),Enterococcus faecalis (E.faecalis) and Gram-negative Escherichia coli (E.coli),Pseudomonasaeruginosa (P.aeruginosa) reference strains. Concerning the influence of Fe 3 O 4 @UA on the planktonic bacterial cells, the functionalized magnetic nanoparticles exhibited a significantly improved antimicrobial activity against E.faecalis and E.coli, as compared with the Fe 3 O 4 control. The UA incorporated into the magnetic nanoparticles exhibited a very significant inhibitory effect on the biofilm formed by the S.aureus and E.faecalis, on a wide range of concentrations, while in case of the Gram-negative microbial strains, the UA-loaded nanoparticles inhibited the E.coli biofilm development, only at high concentrations, while for P.aeruginosa biofilms, no inhibitory effect was observed. The obtained results demonstrate that the new water-dispersible Fe 3 O 4 @UA nanosystem, combining the advantages of the intrinsic antimicrobial features of the UA with the higher surface to volume ratio provided by the magnetic nanocarrier dispersible in water, exhibits efficient antimicrobial activity against planktonic and adherent cells, especially on Gram-positive strains

A laboratory dispersant effectiveness test which reflects dispersant efficiency in the field

International Nuclear Information System (INIS)

Lunel, T.; Wood, P.

1996-01-01

Oil dispersion efficiencies of surfactants, from laboratory dispersion tests and field data were compared and calibrated. Data from an oil spill, where dispersants were used as a major part of the response, was analysed. The data was accumulated through the monitoring of the dispersant operation of the Sea Empress spill incident, in which Forties Blend oil was spilled at sea. This detailed data set was used to calibrate existing laboratory dispersant tests, and to devise a new International Dispersant Effectiveness Test. The objective was to create a comprehensive guide to decision making on whether and when to start a dispersant spraying operation. The dispersion efficiencies obtained from the laboratory dispersant tests were compared with field data. Flume tests produced the highest percentage of dispersed oil for all the dispersal tests. However, it was emphasised that the total percentage of oil dispersed should not be the only measure of dispersant effectiveness, since it does not distinguish between the contribution of natural and chemically enhanced dispersion. 9 refs., 1 tab., 9 figs

Does ascorbic acid supplementation affect iron bioavailability in rats fed micronized dispersible ferric pyrophosphate fortified fruit juice?

Science.gov (United States)

Haro-Vicente, Juan Francisco; Pérez-Conesa, Darío; Rincón, Francisco; Ros, Gaspar; Martínez-Graciá, Carmen; Vidal, Maria Luisa

2008-12-01

Food iron (Fe) fortification is an adequate approach for preventing Fe-deficiency anemia. Poorly water-soluble Fe compounds have good sensory attributes but low bioavailability. The reduction of the particle size of Fe fortificants and the addition of ascorbic acid might increase the bioavailability of low-soluble compounds. The present work aims to compare the Fe absorption and bioavailability of micronized dispersible ferric pyrophosphate (MDFP) (poorly soluble) to ferrous sufate (FS) (highly soluble) added to a fruit juice in presence or absence of ascorbic acid (AA) by using the hemoglobin repletion assay in rats. After a hemoglobin depletion period, four fruit juices comprised of (1) FS, (2) MDFP, (3) FS + AA, (4) MDFP + AA were produced and administered to a different group of rats (n = 18) over 21 days. During the repletion period, Fe balance, hemoglobin regeneration efficiency (HRE), relative bioavailability (RBV) and Fe tissue content were determined in the short, medium and long term. Fe absorption and bioavailability showed no significant differences between fortifying the fruit juice with FS or MDFP. The addition of AA to the juice enhanced Fe absorption during the long-term balance study within the same Fe source. HRE and Fe utilization increased after AA addition in both FS and MDFP groups in every period. Fe absorption and bioavailability from MDFP were comparable to FS added to a fruit juice in rats. Further, the addition of AA enhanced Fe absorption in the long term, as well as Fe bioavailability throughout the repletion period regardless of the Fe source employed.

Determination of phthalic acid esters in Chinese white spirit using dispersive liquid-liquid microextraction coupled with sweeping β-cyclodextrin-modified micellar electrokinetic chromatography.

Science.gov (United States)

Sun, Jianzhi; He, Hui; Liu, Shuhui

2014-07-01

A simple method that consumes low organic solvent is proposed for the analysis of phthalic acid esters in Chinese white spirit using dispersive liquid-liquid microextraction coupled with sweeping-micellar electrokinetic chromatography. Tetrachloromethane and white-spirit-containing ethanol were used as the extraction and dispersing solvents, respectively. The electrophoresis separation buffer was composed of 5 mM β-cyclodextrin, 50 mM sodium dodecyl sulfate and 25 mM borate buffer (pH 9.2) with 9% acetonitrile, enabling the baseline resolution of the analytes within 13 min. Under the optimum conditions, satisfactory linearities (5-1000 ng/mL, r ≥ 0.9909), good reproducibility (RSD ≤ 6.7% for peak area, and RSD ≤ 2.8% for migration time), low detection limits (0.4-0.8 ng/mL) and acceptable recovery rates (89.6-105.7%) were obtained. The proposed method was successfully applied to 22 Chinese white spirits, and the content of dibutyl phthalate in 55% of the samples exceeded the Specific Migration Limit of 0.3 mg/kg established by the domestic and international regulations. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evaluation of the effects of nanoscale zero-valent iron (nZVI) dispersants on intrinsic biodegradation of trichloroethylene (TCE).

Science.gov (United States)

Chang, Y C; Huang, S C; Chen, K F

2014-01-01

In this study, the biodegradability of nanoscale zero-valent iron (nZVI) dispersants and their effects on the intrinsic biodegradation of trichloroethylene (TCE) were evaluated. Results of a microcosm study show that the biodegradability of three dispersants followed the sequence of: polyvinyl alcohol-co-vinyl acetate-co-itaconic acid (PV3A) > polyoxyethylene (20) sorbitan monolaurate (Tween 20) > polyacrylic acid (PAA) under aerobic conditions, and PV3A > Tween 20 > PAA under anaerobic conditions. Natural biodegradation of TCE was observed under both aerobic and anaerobic conditions. No significant effects were observed on the intrinsic biodegradation of TCE under aerobic conditions with the presence of the dispersants. The addition of PAA seemed to have a slightly adverse impact on anaerobic TCE biodegradation. Higher accumulation of the byproducts of anaerobic TCE biodegradation was detected with the addition of PV3A and Tween 20. The diversity of the microbial community was enhanced under aerobic conditions with the presence of more biodegradable PV3A and Tween 20. The results of this study indicate that it is necessary to select an appropriate dispersant for nZVI to prevent a residual of the dispersant in the subsurface. Additionally, the effects of the dispersant on TCE biodegradation and the accumulation of TCE biodegrading byproducts should also be considered.

Potassium iodate assisted synthesis of titanium dioxide nanoparticles with superior water-dispersibility.

Science.gov (United States)

Wang, Yawen; Duo, Fangfang; Peng, Shiqi; Jia, Falong; Fan, Caimei

2014-09-15

In this paper, we report a novel polyol process to synthesize highly water-dispersible anatase titanium dioxide (TiO2) nanoparticles (∼5 nm) by the introduction of inorganic oxidizing agent--KIO3. The obtained TiO2 nanoparticles are well dispersible in water at pH≥5.0 and the resulting aqueous dispersion remains stable over months. The superior water-dispersibility of as-formed TiO2 is ascribed to the electrostatic repulsion from carboxylic acid group modified on TiO2 nanoparticles, which is the oxidation product of solvent diethylene glycol (DEG) by KIO3. Based on the characterization results, the formation processes of water-dispersibility TiO2 nanoparticles are proposed. Meanwhile, the synthesized TiO2 nanoparticles are found to be doped by iodine and exhibit excellent photocatalytic activity on degradation of rhodamine-B (RhB) under visible-light irradiation. The further tests demonstrate that the O(2-) is the main active species during photodegradation of RhB. Copyright © 2014 Elsevier Inc. All rights reserved.

Characterization and Catalytic Performance of Niobic Acid Dispersed over Titanium Silicalite

Directory of Open Access Journals (Sweden)

Didik Prasetyoko

2008-01-01

Full Text Available Niobic acid, Nb2O5⋅nH2O, has been supported on the titanium silicalite by impregnation method. The obtained materials were characterized by X-ray diffraction, infrared, and ultra-violet—visible diffuse reflectance spectroscopy, temperature programmed reduction, pyridine adsorption, and field emission scanning electron microscopy techniques. It was demonstrated that the tetrahedral titanium species still retained after impregnation of niobic acid. The results revealed that niobium species interacted with hydroxyl groups on the surface of TS-1. The niobium species in the catalysts are predominantly polymerized niobium oxides species or bulk niobium oxide with the octahedral structure. All catalysts showed both Brønsted and Lewis acid sites. The catalysts have been tested for epoxidation of 1-octene with aqueous hydrogen peroxide. It was found that the presence of niobic acid in the catalysts enhanced the rate of the formation of epoxide at the initial reaction time. Diol as a side product was also observed due to the acidic properties of the catalysts.

Determination of valproic acid in human plasma using dispersive liquid-liquid microextraction followed by gas chromatography-flame ionization detection

Science.gov (United States)

Fazeli-Bakhtiyari, Rana; Panahi-Azar, Vahid; Sorouraddin, Mohammad Hossein; Jouyban, Abolghasem

2015-01-01

Objective(s): Dispersive liquid-liquid microextraction coupled with gas chromatography (GC)-flame ionization detector was developed for the determination of valproic acid (VPA) in human plasma. Materials and Methods: Using a syringe, a mixture of suitable extraction solvent (40 µl chloroform) and disperser (1 ml acetone) was quickly added to 10 ml of diluted plasma sample containing VPA (pH, 1.0; concentration of NaCl, 4% (w/v)), resulting in a cloudy solution. After centrifugation (6000 rpm for 6 min), an aliquot (1 µl) of the sedimented organic phase was removed using a 1-µl GC microsyringe and injected into the GC system for analysis. One variable at a time optimization method was used to study various parameters affecting the extraction efficiency of target analyte. Then, the developed method was fully validated for its accuracy, precision, recovery, stability, and robustness. Results: Under the optimum extraction conditions, good linearity range was obtained for the calibration graph, with correlation coefficient higher than 0.998. Limit of detection and lower limit of quantitation were 3.2 and 6 μg/ml, respectively. The relative standard deviations of intra and inter-day analysis of examined compound were less than 11.5%. The relative recoveries were found in the range of 97 to 107.5%. Finally, the validated method was successfully applied to the analysis of VPA in patient sample. Conclusion: The presented method has acceptable levels of precision, accuracy and relative recovery and could be used for therapeutic drug monitoring of VPA in human plasma. PMID:26730332

Design of in situ dispersible and calcium cross-linked alginate pellets as intestinal-specific drug carrier by melt pelletization technique.

Science.gov (United States)

Nurulaini, Harjoh; Wong, Tin Wui

2011-06-01

Conventional alginate pellets underwent rapid drug dissolution and loss of multiparticulate characteristics such as aggregation in acidic medium, thereby promoting oral dose dumping. This study aimed to design sustained-release dispersible alginate pellets through rapid in situ matrix dispersion and cross-linking by calcium salts during dissolution. Pellets made of alginate and calcium salts were prepared using a solvent-free melt pelletization technique that prevented reaction between processing materials during agglomeration and allowed such a reaction to occur only in dissolution phase. Drug release was remarkably retarded in acidic medium when pellets were formulated with water-soluble calcium acetate instead of acid-soluble calcium carbonate. Different from calcium salt-free and calcium carbonate-loaded matrices that aggregated or underwent gradual erosion, rapid in situ solvation of calcium acetate in pellets during dissolution resulted in burst of gas bubbles, fast pellet breakup, and dispersion. The dispersed fragments, though exhibiting a larger specific surface area for drug dissolution than intact matrix, were rapidly cross-linked by Ca(2+) from calcium acetate and had drug release retarded till a change in medium pH from 1.2 to 6.8. Being dispersible and pH-dependent in drug dissolution, these pellets are useful as multiparticulate intestinal-specific drug carrier without exhibiting dose dumping tendency of a "single-unit-like" system via pellet aggregation. Copyright © 2011 Wiley-Liss, Inc.

Functionalization of surfactant wrapped graphenenanosheets with alkylazides for enhanced dispersibility

Science.gov (United States)

Vadukumpully, Sajini; Gupta, Jhinuk; Zhang, Yongping; Xu, Guo Qin; Valiyaveettil, Suresh

2011-01-01

A facile and simple approach for the covalent functionalization of surfactant wrapped graphene sheets is described. The approach involves functionalization of dispersible graphene sheets with various alkylazides and 11-azidoundecanoic acid proved the best azide for enhanced dispersibility. The functionalization was confirmed by infrared spectroscopy and scanning tunneling microscopy. The free carboxylic acidgroups can bind to gold nanoparticles, which were introduced as markers for the reactive sites. The interaction between gold nanoparticles and the graphene sheets was followed by UV-vis spectroscopy. The gold nanoparticle-graphene composite was characterized by transmission electron microscopy and atomic force microscopy, demonstrating the uniform distribution of gold nanoparticles all over the surface. Our results open the possibility to control the functionalization on graphene in the construction of composite nanomaterials.A facile and simple approach for the covalent functionalization of surfactant wrapped graphene sheets is described. The approach involves functionalization of dispersible graphene sheets with various alkylazides and 11-azidoundecanoic acid proved the best azide for enhanced dispersibility. The functionalization was confirmed by infrared spectroscopy and scanning tunneling microscopy. The free carboxylic acidgroups can bind to gold nanoparticles, which were introduced as markers for the reactive sites. The interaction between gold nanoparticles and the graphene sheets was followed by UV-vis spectroscopy. The gold nanoparticle-graphene composite was characterized by transmission electron microscopy and atomic force microscopy, demonstrating the uniform distribution of gold nanoparticles all over the surface. Our results open the possibility to control the functionalization on graphene in the construction of composite nanomaterials. Electronic Supplementary Information (ESI) available: Synthesis and characterization details of dodecylazide

Unique coexistence of dispersion stability and nanoparticle chemisorption in alkylamine/alkylacid encapsulated silver nanocolloids.

Science.gov (United States)

Aoshima, Keisuke; Hirakawa, Yuya; Togashi, Takanari; Kurihara, Masato; Arai, Shunto; Hasegawa, Tatsuo

2018-04-17

Surface encapsulation of metal nanoparticles (NPs) is fundamental to achieve sufficient dispersion stability of metal nanocolloids, or metal nanoink. However, the feature is incompatible with surface reactive nature of the metal NPs, although these features are both essential to realizing the functional applications into printed electronics technologies. Here we show that two different kinds of encapsulation for silver NPs (AgNPs) by alkylamine and alkylacid together are the key to achieve unique compatibility between the high dispersion stability as dense nanoclolloids and the AgNP chemisorption printing on activated patterned polymer surfaces. Advanced confocal dynamic light scattering study reveals that an additive trace amount of oleic acid is the critical parameter for controlling the dispersion and coagulative (or surface-reactive) characteristics of the silver nanocolloids. The composition of the disperse media is also important for obtaining highly concentrated but low-viscosity silver nanocolloids that show very stable dispersion. The results demonstrate that the high-resolution AgNP chemisorption printing is possible only by using unique silver nanocolloids composed of an exceptional balance of ligand formulation and dispersant composition.

Dispersion bias, dispersion effect, and the aerosol-cloud conundrum

International Nuclear Information System (INIS)

Liu Yangang; Daum, Peter H; Guo Huan; Peng Yiran

2008-01-01

This work examines the influences of relative dispersion (the ratio of the standard deviation to the mean radius of the cloud droplet size distribution) on cloud albedo and cloud radiative forcing, derives an analytical formulation that accounts explicitly for the contribution from droplet concentration and relative dispersion, and presents a new approach to parameterize relative dispersion in climate models. It is shown that inadequate representation of relative dispersion in climate models leads to an overestimation of cloud albedo, resulting in a negative bias of global mean shortwave cloud radiative forcing that can be comparable to the warming caused by doubling CO 2 in magnitude, and that this dispersion bias is likely near its maximum for ambient clouds. Relative dispersion is empirically expressed as a function of the quotient between cloud liquid water content and droplet concentration (i.e., water per droplet), yielding an analytical formulation for the first aerosol indirect effect. Further analysis of the new expression reveals that the dispersion effect not only offsets the cooling from the Twomey effect, but is also proportional to the Twomey effect in magnitude. These results suggest that unrealistic representation of relative dispersion in cloud parameterization in general, and evaluation of aerosol indirect effects in particular, is at least in part responsible for several outstanding puzzles of the aerosol-cloud conundrum: for example, overestimation of cloud radiative cooling by climate models compared to satellite observations; large uncertainty and discrepancy in estimates of the aerosol indirect effect; and the lack of interhemispheric difference in cloud albedo.

Effect of l-lysine-assisted surface grafting for nano-hydroxyapatite on mechanical properties and in vitro bioactivity of poly(lactic acid-co-glycolic acid).

Science.gov (United States)

Liuyun, Jiang; Lixin, Jiang; Chengdong, Xiong; Lijuan, Xu; Ye, Li

2016-01-01

It is promising and challenging to study surface modification for nano-hydroxyapatite to improve the dispersion and enhance the mechanical properties and bioactivity of poly(lactic acid-co-glycolic acid). In this paper, we designed an effective new surface grafting with the assist of l-lysine for nano-hydroxyapatite, and the nano-hydroxyapatite surface grafted with the assist of l-lysine (g-nano-hydroxyapatite) was incorporated into poly(lactic acid-co-glycolic acid) to develop a series of g-nano-hydroxyapatite/poly(lactic acid-co-glycolic acid) nano-composites. The surface modification reaction for nano-hydroxyapatite, the mechanical properties, and in vitro human osteoblast-like cell (MG-63) response were characterized and investigated by Fourier transformation infrared, thermal gravimetric analysis, dispersion test, electromechanical universal tester, differential scanning calorimeter measurements, and in vitro cells culture experiment. The results showed that the grafting amount on the surface of nano-hydroxyapatite was enhanced with the increase of l-lysine, and the dispersion of nano-hydroxyapatite was improved more, so that it brought about better promotion crystallization and more excellent mechanical enhancement effect for poly(lactic acid-co-glycolic acid), comparing with the unmodified nano-hydroxyapatite. Moreover, the cells' attachment and proliferation results confirmed that the incorporation of the g-nano-hydroxyapatite into poly(lactic acid-co-glycolic acid) exhibited better biocompatibility than poly(lactic acid-co-glycolic acid). The above results indicated that the new surface grafting with the assist of l-lysine for nano-hydroxyapatite was an ideal novel surface modification method, which brought about better mechanical enhancement effect and in vitro bioactivity for poly(lactic acid-co-glycolic acid) with adding higher g-nano-hydroxyapatite content, suggesting it had a great potential to be used as bone fracture internal fixation materials

Magnetoviscous effect in ferrofluids with different dispersion media

Energy Technology Data Exchange (ETDEWEB)

Borin, D.Yu [TU Dresden, Institute of Fluid Mechanics, Dresden 01062 (Germany); Korolev, V.V. [G.A. Krestov Institute of Solution Chemistry of the Russian Academy of Sciences, Ivanovo (Russian Federation); Ramazanova, A.G., E-mail: agr@isc-ras.ru [G.A. Krestov Institute of Solution Chemistry of the Russian Academy of Sciences, Ivanovo (Russian Federation); Odenbach, S. [TU Dresden, Institute of Fluid Mechanics, Dresden 01062 (Germany); Balmasova, O.V.; Yashkova, V.I. [G.A. Krestov Institute of Solution Chemistry of the Russian Academy of Sciences, Ivanovo (Russian Federation); Korolev, D.V. [Federal Sate Unitary Enterprise all Russian Scientific Research Institute of Aviation Materials (Russian Federation)

2016-10-15

Ferrofluids based on magnetite nanoparticles dispersed in different carrier media (dialkyldiphenyl and polyethylsiloxane) have been synthesized using mixed surfactants (oleic acid, stearic acid and alkenyl succinic anhydride). Magnetic properties of the samples and a change of their shear viscosities in an applied magnetic field have been studied in order to evaluate an influence of the carrier medium on a magnetoviscous effect. A significance of the interaction of the carrier medium and surfactant with a consideration of the magnetic and rheological behavior of ferrofluids was demonstrated. - Highlights: • Ferrofluids based on mixed surfactants were synthesized. • Oleic, stearic acid and alkenylsuccinic anhydride were used. • The nature of the surfactant has a high impact on the ferrofluids' shear viscosity. • The core size distribution is not the only determining reason of the structuring. • Significance of the interaction of the carrier medium and surfactant is demonstrated.

Dispersion, sorption and photodegradation of petroleum hydrocarbons in dispersant-seawater-sediment systems.

Science.gov (United States)

Zhao, Xiao; Liu, Wen; Fu, Jie; Cai, Zhengqing; O'Reilly, S E; Zhao, Dongye

2016-08-15

This work examined effects of model oil dispersants on dispersion, sorption and photodegradation of petroleum hydrocarbons in simulated marine systems. Three dispersants (Corexit 9500A, Corexit 9527A and SPC 1000) were used to prepare dispersed water accommodated oil (DWAO). While higher doses of dispersants dispersed more n-alkanes and PAHs, Corexit 9500A preferentially dispersed C11-C20 n-alkanes, whereas Corexit 9527A was more favorable for smaller alkanes (C10-C16), and SPC 1000 for C12-C28 n-alkanes. Sorption of petroleum hydrocarbons on sediment was proportional to TPH types/fractions in the DWAOs. Addition of 18mg/L of Corexit 9500A increased sediment uptake of 2-3 ring PAHs, while higher dispersant doses reduced the uptake, due to micelle-enhanced solubilization effects. Both dispersed n-alkanes and PAHs were susceptible to photodegradation under simulated sunlight. For PAHs, both photodegradation and photo-facilitated alkylation were concurrently taking place. The information can facilitate sounder assessment of fate and distribution of dispersed oil hydrocarbons in marine systems. Copyright © 2016 Elsevier Ltd. All rights reserved.

Synthesis and Evaluation of Changes Induced by Solvent and Substituent in Electronic Absorption Spectra of New Azo Disperse Dyes Containig Barbiturate Ring

Directory of Open Access Journals (Sweden)

Hooshang Hamidian

2013-01-01

Full Text Available Six azo disperse dyes were prepared by diazotizing 4-amino hippuric acid and coupled with barbituric acid and 2-thiobarbituric acid. Then, the products were reacted with aromatic aldehyde, sodium acetate, and acetic anhydride, and oxazolone derivatives were formed. Characterization of the dyes was carried out by using UV-Vis, FT-IR, 1H NMR and 13C NMR, and mass spectroscopic techniques. The solvatochromic behavior of azo disperse dyes was evaluated in various solvents. The effects of substituents of aromatic aldehyde, barbiturate, and thiobarbiturate ring on the color of dyes were investigated.

Mutagenicity of diesel exhaust soot dispersed in phospholipid surfactants

Energy Technology Data Exchange (ETDEWEB)

Wallace, W.; Keane, M.; Xing, S.; Harrison, J.; Gautam, M.; Ong, T.

1994-06-01

Organics extractable from respirable diesel exhaust soot particles by organic solvents have been known for some time to be direct acting frameshift mutagens in the Ames Salmonella typhimurium histidine reversion assay. Upon deposition in a pulmonary alveolus or respiratory bronchiole, respirable diesel soot particles will contact first the hypophase which is coated by and laden with surfactants. To model interactions of soot and pulmonary surfactant, the authors dispersed soots in vitro in the primary phospholipid pulmonary surfactant dipalmitoyl glycerophosphorylcholine (lecithin) (DPL) in physiological saline. They have shown that diesel soots dispersed in lecithin surfactant can express mutagenic activity, in the Ames assay system using S. typhimurium TA98, comparable to that expressed by equal amounts of soot extracted by dichloromethane/dimethylsulfoxide (DCM/DMSO). Here the authors report additional data on the same system using additional exhaust soots and also using two other phospholipids, dipalmitoyl glycerophosphoryl ethanolamine (DPPE), and dipalmitoyl phosphatidic acid (DPPA), with different ionic character hydrophilic moieties. A preliminary study of the surfactant dispersed soot in an eucaryotic cell test system also is reported.

Life cycle assessment of residual lignocellulosic biomass-based jet fuel with activated carbon and lignosulfonate as co-products.

Science.gov (United States)

Pierobon, Francesca; Eastin, Ivan L; Ganguly, Indroneil

2018-01-01

Bio-jet fuels are emerging as a valuable alternative to petroleum-based fuels for their potential for reducing greenhouse gas emissions and fossil fuel dependence. In this study, residual woody biomass from slash piles in the U.S. Pacific Northwest is used as a feedstock to produce iso-paraffinic kerosene, through the production of sugar and subsequent patented proprietary fermentation and upgrading. To enhance the economic viability and reduce the environmental impacts of iso-paraffinic kerosene, two co-products, activated carbon and lignosulfonate, are simultaneously produced within the same bio-refinery. A cradle-to-grave life cycle assessment (LCA) is performed for the residual woody biomass-based bio-jet fuel and compared against the cradle-to-grave LCA of petroleum-based jet fuel. This paper also discusses the differences in the environmental impacts of the residual biomass-based bio-jet fuel using two different approaches, mass allocation and system expansion, to partition the impacts between the bio-fuel and the co-products, which are produced in the bio-refinery. The environmental assessment of biomass-based bio-jet fuel reveals an improvement along most critical environmental criteria, as compared to its petroleum-based counterpart. However, the results present significant differences in the environmental impact of biomass-based bio-jet fuel, based on the partitioning method adopted. The mass allocation approach shows a greater improvement along most of the environmental criteria, as compared to the system expansion approach. However, independent of the partitioning approach, the results of this study reveal that more than the EISA mandated 60% reduction in the global warming potential could be achieved by substituting petroleum-based jet fuel with residual woody biomass-based jet fuel. Converting residual woody biomass from slash piles into bio-jet fuel presents the additional benefit of avoiding the impacts of slash pile burning in the forest, which

Dispersion and Stabilization of Photocatalytic TiO2 Nanoparticles in Aqueous Suspension for Coatings Applications

Directory of Open Access Journals (Sweden)

Siti Hajar Othman

2012-01-01

Full Text Available To produce titanium dioxide (TiO2 nanoparticle coatings, it is desirable that the nanoparticles are dispersed into a liquid solution and remain stable for a certain period of time. Controlling the dispersion and aggregation of the nanoparticles is crucial to exploit the advantages of the nanometer-sized TiO2 particles. In this work, TiO2 nanoparticles were dispersed and stabilized in aqueous suspensions using two common dispersants which were polyacrylic acid (PAA and ammonium polymethacrylate (Darvan C. The effect of parameters such as ultrasonication amplitude and type and amount of dispersants on the dispersibility and stability of the TiO2 aqueous suspensions were examined. Rupture followed by erosion was determined to be the main break up mechanisms when ultrasonication was employed. The addition of dispersant was found to produce more dispersed and more stabilized aqueous suspension. 3 wt.% of PAA with average molecular weight (Mw of 2000 g/mol (PAA 2000 was determined to produce the best and most stable dispersion. The suspensions were then coated on quartz glass, whereby the photocatalytic activity of the coatings was studied via the degradation of formaldehyde gas under UV light. The coatings were demonstrated to be photocatalytically active.

Carbon nanotube modification using gum arabic and its effect on the dispersion and tensile properties of carbon nanotubes/epoxy nanocomposites.

Science.gov (United States)

Kim, Man Tae; Park, Ho Seok; Hui, David; Rhee, Kyong Yop

2011-08-01

In this study, the effects of a MWCNT treatment on the dispersion of MWCNTs in aqueous solution and the tensile properties of MWCNT/epoxy nanocomposites were investigated. MWCNTs were treated using acid and gum arabic, and MWCNT/epoxy nanocomposites were fabricated with 0.3 wt.% unmodified, oxidized and gum-treated MWCNTs. The dispersion states of the unmodified, oxidized, and Gum-treated MWCNTs were characterized in distilled water. The tensile strengths and elastic modulus of the three nanocomposites were determined and compared. The results indicated that the gum treatment produced better dispersion of the MWCNTs in distilled water and that gum-treated MWCNT/epoxy nanocomposites had a better tensile strength and elastic modulus than did the unmodified and acid-treated MWCNT/epoxy nanocomposites. Scanning electron microscope examination of the fracture surface showed that the improved tensile properties of the gum-treated MWCNT/epoxy nanocomposites were attributed to the improved dispersion of MWCNTs in the epoxy and to interfacial bonding between nanotubes and the epoxy matrix.

Effects of chemical dispersants on oil physical properties and dispersion. Volume 1

International Nuclear Information System (INIS)

Khelifa, A.; Fingas, M.; Hollebone, B.P.; Brown, C.E.; Pjontek, D.

2007-01-01

Laboratory and field testing have shown that the dispersion of oil spilled in water is influenced by chemical dispersants via the modification of the interfacial properties of the oil, such as oil-brine interfacial tension (IFT). This study focused on new laboratory experiments that measured the effects on the physical properties and dispersion of oil, with particular reference to the effects of chemical dispersants on IFT and oil viscosity and the subsequent effects on oil droplet formation. Experiments were conducted at 15 degrees C using Arabian Medium, Alaska North Slope and South Louisiana crude and Corexit 9500 and Corexit 9527 chemical dispersants. The dispersants were denser than the 3 oils. The effect of IFT reduction on oil dispersion was measured and showed substantial reduction in the size and enhancement of the concentration of oil droplets in the water column. It was shown that the brine-oil IFT associated with the 3 crudes reduced to less than 3.6 mN/m with the application of the chemical dispersants, even at a low dispersant-to-oil ratio (DOR) value of 1:200. The use of chemical dispersants increased the viscosity of the dispersant-oil mixture up to 40 per cent over the neat crude oil. It was shown that for each mixing condition, an optimum value of DOR exists that provides for maximal dispersant effectiveness. The IFT reaches maximum reduction at optimum DOR. It was suggested that oil spill modelling can be improved with further study of IFT reduction with DOR and variations of critical micelle concentration with the type and solubility of chemical dispersant, oil type and oil to water ratio. 13 refs., 3 tabs., 7 figs

Chemical by-products from spent sulfite liquors

Energy Technology Data Exchange (ETDEWEB)

Whitmore, Jr, L M; Wiley, A J

1958-01-01

Current practices for recovering sugars, lignosulfonates, ethanol and feed yeast and product uses are reviewed. A process for separating sugars is described in which the sulfite liquor is spray dried and refluxed with acetone containing a concentrated H/sub 2/SO/sub 4/ catalyst, and the di-acetone sugar derivatives are filtered or centrifuged from the acetone insolubles. Recovery of guaiacyl and syringyl derivatives from the lignosulfonate portion of the liquor is discussed.

Removal of Disperse Blue 56 and Disperse Red 135 dyes from aqueous dispersions by modified montmorillonite nanoclay

Directory of Open Access Journals (Sweden)

Ahmadishoar Javad

2017-01-01

Full Text Available In this study modified montmorillonite was used as an adsorbent for the removal of two selected disperse dyes i.e., Disperse Blue 56 (DB and Disperse Red 135 (DR from dye dispersions. The adsorption equilibrium data of dyes adsorption were investigated by using Nernst, Freundlich and Langmuir isotherm models. The adsorption kinetics was analyzed by using different models including pseudo-first-order, pseudo-second-order, Elovich and Intraparticle diffusion model. The Freundlich isotherm was found to be the most appropriate model for describing the sorption of the dyes on modified nanoclay. The best fit to the experimental results was obtained by using the pseudo-second-order kinetic equation, which satisfactorily described the process of dye adsorption. Although different kinetic models may control the rate of the adsorption process, the results indicated that the main rate limiting step was the intraparticle diffusion. The results showed that the proposed modified montmorillonite could be used as an effective adsorbent for the removal of disperse dyes even from highly concentrated dispersions.

High throughput screening of phenoxy carboxylic acids with dispersive solid phase extraction followed by direct analysis in real time mass spectrometry.

Science.gov (United States)

Wang, Jiaqin; Zhu, Jun; Si, Ling; Du, Qi; Li, Hongli; Bi, Wentao; Chen, David Da Yong

2017-12-15

A high throughput, low environmental impact methodology for rapid determination of phenoxy carboxylic acids (PCAs) in water samples was developed by combing dispersive solid phase extraction (DSPE) using velvet-like graphitic carbon nitride (V-g-C 3 N 4 ) and direct analysis in real time mass spectrometry (DART-MS). Due to the large surface area and good dispersity of V-g-C 3 N 4 , the DSPE of PCAs in water was completed within 20 s, and the elution of PCAs was accomplished in 20 s as well using methanol. The eluents were then analyzed and quantified using DART ionization source coupled to a high resolution mass spectrometer, where an internal standard was added in the samples. The limit of detection ranged from 0.5 ng L -1 to 2 ng L -1 on the basis of 50 mL water sample; the recovery 79.9-119.1%; and the relative standard deviation 0.23%-9.82% (≥5 replicates). With the ease of use and speed of DART-MS, the whole protocol can complete within mere minutes, including sample preparation, extraction, elution, detection and quantitation. The methodology developed here is simple, fast, sensitive, quantitative, requiring little sample preparation and consuming significantly less toxic organic solvent, which can be used for high throughput screening of PCAs and potentially other contaminants in water. Copyright © 2017 Elsevier B.V. All rights reserved.

Water- and organo-dispersible gold nanoparticles supported by using ammonium salts of hyperbranched polystyrene: preparation and catalysis.

Science.gov (United States)

Gao, Lei; Nishikata, Takashi; Kojima, Keisuke; Chikama, Katsumi; Nagashima, Hideo

2013-12-01

Gold nanoparticles (1 nm in size) stabilized by ammonium salts of hyperbranched polystyrene are prepared. Selection of the R groups provides access to both water- and organo-dispersible gold nanoparticles. The resulting gold nanoparticles are subjected to studies on catalysis in solution, which include reduction of 4-nitrophenol with sodium borohydride, aerobic oxidation of alcohols, and homocoupling of phenylboronic acid. In the reduction of 4-nitrophenol, the catalytic activity is clearly dependent on the size of the gold nanoparticles. For the aerobic oxidation of alcohols, two types of biphasic oxidation are achieved: one is the catalyst dispersing in the aqueous phase, whereas the other is in the organic phase. The catalysts are reusable more than four times without loss of the catalytic activity. Selective synthesis of biphenyl is achieved by the homocoupling of phenylboronic acid catalyzed by organo-dispersible gold nanoparticles. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Novel star-like surfactant as dispersant for multi-walled carbon nanotubes in aqueous suspensions at high concentration

Science.gov (United States)

Qiao, Min; Ran, Qianping; Wu, Shishan

2018-03-01

A kind of novel surfactant with star-like molecular structure and terminated sulfonate was synthesized, and it was used as the dispersant for multi-walled carbon nanotubes (CNTs) in aqueous suspensions compared with a traditional single-chained surfactant. The star-like surfactant showed good dispersing ability for multi-walled CNTs in aqueous suspensions. Surface tension analysis, total organic carbon analysis, X-ray photoelectron spectroscopy, zeta potential, dynamic light scattering and transmission electron microscopy were performed to research the effect of star-like surfactant on the dispersion of multi-walled CNTs in aqueous suspensions. With the assistance of star-like surfactant, the CNTs could disperse well in aqueous suspension at high concentration of 50 g/L for more than 30 days, while the CNTs precipitated completely in aqueous suspension after 1 day without any dispersant or after 10 days with sodium 4-dodecylbenzenesulfonic acid as dispersant.

Structure and crystallinity of water dispersible photoactive nanoparticles for organic solar cells

DEFF Research Database (Denmark)

Pedersen, Emil Bøje Lind; Pedersen, M.C.; Simonsen, Søren Bredmose

2015-01-01

Water based inks would be a strong advantage for large scale production of organic photovoltaic devices. Formation of water dispersible nanoparticles produced by the Landfester method is a promising route to achieve such inks. We provide new insights into the key ink properties of poly(3-hexylthi......Water based inks would be a strong advantage for large scale production of organic photovoltaic devices. Formation of water dispersible nanoparticles produced by the Landfester method is a promising route to achieve such inks. We provide new insights into the key ink properties of poly(3......-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) nanoparticles such as the internal structure and crystallinity of the dispersed nanoparticles and the previously unreported drastic changes that occur when the inks are cast into a film. We observe through transmission electron...

BaTiO3–P(VDF-HFP) nanocomposite dielectrics—Influence of surface modification and dispersion additives

International Nuclear Information System (INIS)

Ehrhardt, Claudia; Fettkenhauer, Christian; Glenneberg, Jens; Münchgesang, Wolfram; Pientschke, Christoph; Großmann, Thomas; Zenkner, Mandy; Wagner, Gerald; Leipner, Hartmut S.; Buchsteiner, Alexandra; Diestelhorst, Martin; Lemm, Sebastian; Beige, Horst; Ebbinghaus, Stefan G.

2013-01-01

Highlights: • Polymer composites were prepared using a sol–gel synthesized BaTiO 3 . • BaTiO 3 surface hydroxyle groups act as linkers for surfactant molecules. • The effect of chemical adjustment between surfactant and polymer host is studied. • A positive effect of an additional dispersant was found. • Dielectric properties of the resulting composite films are presented. -- Abstract: We report on BaTiO 3 –polymer composites as dielectrics for film capacitors. BaTiO 3 was synthesized by a sol–gel soft-chemistry method leading to spherical nanoparticles with a high degree of surface hydroxyl groups which turned out to be important for the bonding of surfactant molecules. As surfactants, n-octylphosphonic acid and 2,3,4,5,6-pentafluorobenzyl phosphonic acid were used to inhibit particle agglomeration and to improve the wetting behaviour with the polymer. The phosphonic acid-coated BaTiO 3 nanoparticles were dispersed in solutions of poly(vinylidefluoride-co-hexafluoropropylene). Composite films were prepared by the spin-coating technique. A systematic study was performed on the influence of varying oxide fractions, different surfactants and the effect of additional dispersion aids such as sodium dodecyl sulphate or BYK-W 9010 on the quality and dielectric properties of the films obtained. The chemical adjustment of the 2,3,4,5,6-pentaflourobenzyl phosphonic acid within the fluorinated organic host form a more uniform particle distribution and increase relative permittivity of the resulting composite material compared to the unflourinated surfactant. Additionally, an enhancement of the relative permittivity can be realized by adding of dispersants. These two components can increase the relative permittivity by factor 5 compared to the pure polymer material

Amplifying (Im)perfection: The Impact of Crystallinity in Discrete and Disperse Block Co-oligomers.

Science.gov (United States)

van Genabeek, Bas; Lamers, Brigitte A G; de Waal, Bas F M; van Son, Martin H C; Palmans, Anja R A; Meijer, E W

2017-10-25

Crystallinity is seldomly utilized as part of the microphase segregation process in ultralow-molecular-weight block copolymers. Here, we show the preparation of two types of discrete, semicrystalline block co-oligomers, comprising an amorphous oligodimethylsiloxane block and a crystalline oligo-l-lactic acid or oligomethylene block. The self-assembly of these discrete materials results in lamellar structures with unforeseen uniformity in the domain spacing. A systematic introduction of dispersity reveals the extreme sensitivity of the microphase segregation process toward chain length dispersity in the crystalline block.

Nanocomposites from Stable Dispersions of Carbon Nanotubes in Polymeric Matrices Using Dispersion Interaction

Science.gov (United States)

Wise, Kristopher Eric (Inventor); Park, Cheol (Inventor); Kang, Jin Ho (Inventor); Siochi, Emilie J. (Inventor); Harrison, Joycelyn S. (Inventor)

2016-01-01

Stable dispersions of carbon nanotubes (CNTs) in polymeric matrices include CNTs dispersed in a host polymer or copolymer whose monomers have delocalized electron orbitals, so that a dispersion interaction results between the host polymer or copolymer and the CNTs dispersed therein. Nanocomposite products, which are presented in bulk, or when fabricated as a film, fiber, foam, coating, adhesive, paste, or molding, are prepared by standard means from the present stable dispersions of CNTs in polymeric matrices, employing dispersion interactions, as presented hereinabove.

Extracellular Proteins Limit the Dispersal of BiogenicNanoparticles

Energy Technology Data Exchange (ETDEWEB)

Moreau, John W.; Weber, Peter K.; Martin, Michael C.; Gilbert,Benjamin; Hutcheon, Ian D.; Banfield, Jillian F.

2007-04-27

High spatial-resolution secondaryion microprobespectrometry, synchrotron radiation Fourier-transform infraredspectroscopy and polyacrylamide gel analysis demonstrate the intimateassociation of proteins with spheroidal aggregates of biogenic zincsulfide nanocrystals, an example of extracellular biomineralization.Experiments involving synthetic ZnS nanoparticles and representativeamino acids indicate a driving role for cysteine in rapid nanoparticleaggregation. These findings suggest that microbially-derivedextracellular proteins can limit dispersal of nanoparticulatemetal-bearing phases, such as the mineral products of bioremediation,that may otherwise be transported away from their source by subsurfacefluid flow.

Synthesis and properties of catalysts prepared from silicomolybdovanadium heteropoly acid

International Nuclear Information System (INIS)

Chumachenko, N.N.; Tarasova, D.V.; Nikoro, T.A.; Yaroslavtseva, I.V.

1984-01-01

Catalytic properties of samples prepared of silicomolybdovanadium heteropoly acid (HPA) have been investigated. The massive catalyst is shown to be comparatively low effective in the reaction of acrolein oxidation to acrylic acid. Impregnation of coarse-dispersed silica gel by the HPA solution results in the formation of active and selective catalyst, whereas low-active catalyst of deep oxidation is formed on the base of high-dispersed silica gel. The obtained data are explained by the formation and stabilization of different forms of vanadium- and molybdenum-containing compounds on the carrier surface

In vitro activity of the new water-dispersible Fe{sub 3}O{sub 4}@usnic acid nanostructure against planktonic and sessile bacterial cells

Energy Technology Data Exchange (ETDEWEB)

Grumezescu, Alexandru Mihai, E-mail: grumezescu@yahoo.com [Faculty of Applied Chemistry and Materials Science, University Politehnica of Bucharest, Department of Science and Engineering of Oxidic Materials and Nanomaterials (Romania); Cotar, Ani Ioana [Faculty of Biology, University of Bucharest, Department of Microbiology Immunology (Romania); Andronescu, Ecaterina; Ficai, Anton; Ghitulica, Cristina Daniela; Grumezescu, Valentina; Vasile, Bogdan Stefan [Faculty of Applied Chemistry and Materials Science, University Politehnica of Bucharest, Department of Science and Engineering of Oxidic Materials and Nanomaterials (Romania); Chifiriuc, Mariana Carmen [Faculty of Biology, University of Bucharest, Department of Microbiology Immunology (Romania)

2013-07-15

A new water-dispersible nanostructure based on magnetite (Fe{sub 3}O{sub 4}) and usnic acid (UA) was prepared in a well-shaped spherical form by a precipitation method. Nanoparticles were well individualized and homogeneous in size. The presence of Fe{sub 3}O{sub 4}@UA was confirmed by transmission electron microscopy, Fourier transform-infrared spectroscopy, and X-ray diffraction. The UA was entrapped in the magnetic nanoparticles during preparation and the amount of entrapped UA was estimated by thermogravimetric analysis. Fabricated nanostructures were tested on planktonic cells growth (minimal inhibitory concentration assay) and biofilm development on Gram-positive Staphylococcusaureus (S.aureus),Enterococcus faecalis (E.faecalis) and Gram-negative Escherichia coli (E.coli),Pseudomonasaeruginosa (P.aeruginosa) reference strains. Concerning the influence of Fe{sub 3}O{sub 4}@UA on the planktonic bacterial cells, the functionalized magnetic nanoparticles exhibited a significantly improved antimicrobial activity against E.faecalis and E.coli, as compared with the Fe{sub 3}O{sub 4} control. The UA incorporated into the magnetic nanoparticles exhibited a very significant inhibitory effect on the biofilm formed by the S.aureus and E.faecalis, on a wide range of concentrations, while in case of the Gram-negative microbial strains, the UA-loaded nanoparticles inhibited the E.coli biofilm development, only at high concentrations, while for P.aeruginosa biofilms, no inhibitory effect was observed. The obtained results demonstrate that the new water-dispersible Fe{sub 3}O{sub 4}@UA nanosystem, combining the advantages of the intrinsic antimicrobial features of the UA with the higher surface to volume ratio provided by the magnetic nanocarrier dispersible in water, exhibits efficient antimicrobial activity against planktonic and adherent cells, especially on Gram-positive strains.

Aqueous solubility, dispersibility and toxicity of biodiesels

International Nuclear Information System (INIS)

Hollebone, B.P.; Fieldhouse, B.; Lumley, T.C.; Landriault, M.; Doe, K.; Jackman, P.

2007-01-01

The renewed interest in the use of biological fuels can be attributed to that fact that feedstocks for fatty-acid ester biodiesels are renewable and can be reclaimed from waste. Although there are significant benefits to using biodiesels, their increased use leaves potential for accidental release to the environment. Therefore, their environmental behaviours and impacts must be evaluated along with the risk associated with their use. Biodiesel fuels may be made from soy oil, canola oil, reclaimed restaurant grease, fish oil and animal fat. The toxicological fate of biofuel depends on the variability of its chemical composition. This study provided an initial assessment of the aqueous fate and effects of biodiesel from a broad range of commonly available feedstocks and their blends with petroleum diesels. The study focused primarily on the fate and impact of these fuels in fresh-water. The use of chemical dispersion as a countermeasure for saltwater was also investigated. The exposure of aquatic ecosystems to biodiesels and petroleum diesel occurs via the transfer of material from the non-aqueous phase liquid (NAPL) into the aqueous phase, as both soluble and dispersed components. The aqueous solubilities of the fuels were determined from the equilibrium water-accommodated fraction concentrations. The acute toxicities of many biodiesels were reported for 3 test species used by Environment Canada for toxicological evaluation, namely rainbow trout, the water flea and a luminescent bacterium. This study also evaluated the natural potential for dispersion of the fuels in the water column in both low and high-energy wave conditions. Chemical dispersion as a potential countermeasure for biodiesel spills was also evaluated using solubility testing, acute toxicity testing, and dispersibility testing. It was shown that biodiesels have much different fates and impacts from petroleum diesels. The compounds partitioning into the water column are also very different for each

Water solubilization and the dielectric permeability of isomolar solutions of oleic acid and triethanolamine soap of oleic acid

Energy Technology Data Exchange (ETDEWEB)

Demchenko, P.A.; Novitskaya, L.D.

The investigation of the dependence of water solubilization on the dielectric permeability of isomolar solutions of oleic acid and triethanolamine soap of oleic acid in benzene has shown that at certain acid additions, the solubilization effect can increase almost 6 times, as compared to the soap solution without acid additions. In some cases, electron donor-acceptor complexes are formed, which are more polar than the original components. This leads to a change in the molecular-disperse and micellar part of solution and affects significantly the structure and properties of micellar hydrocarbon solutions of surfactants.

BaTiO{sub 3}–P(VDF-HFP) nanocomposite dielectrics—Influence of surface modification and dispersion additives

Energy Technology Data Exchange (ETDEWEB)

Ehrhardt, Claudia; Fettkenhauer, Christian [Institute of Chemistry, Martin-Luther-University Halle-Wittenberg, Kurt-Mothes-Straße 2, D-06120 Halle/Saale (Germany); Glenneberg, Jens [Interdisciplinary Centre of Materials Science, Martin-Luther-University Halle-Wittenberg, Heinrich-Damerow-Straße 4, D-06120 Halle/Saale (Germany); Münchgesang, Wolfram; Pientschke, Christoph [Institute of Physics, Martin-Luther-University Halle-Wittenberg, Von-Danckelmann-Platz 3, D-06120 Halle/Saale (Germany); Großmann, Thomas; Zenkner, Mandy [Institute of Chemistry, Martin-Luther-University Halle-Wittenberg, Kurt-Mothes-Straße 2, D-06120 Halle/Saale (Germany); Wagner, Gerald; Leipner, Hartmut S.; Buchsteiner, Alexandra [Interdisciplinary Centre of Materials Science, Martin-Luther-University Halle-Wittenberg, Heinrich-Damerow-Straße 4, D-06120 Halle/Saale (Germany); Diestelhorst, Martin; Lemm, Sebastian; Beige, Horst [Institute of Physics, Martin-Luther-University Halle-Wittenberg, Von-Danckelmann-Platz 3, D-06120 Halle/Saale (Germany); Ebbinghaus, Stefan G., E-mail: stefan.ebbinghaus@chemie.uni-halle.de [Institute of Chemistry, Martin-Luther-University Halle-Wittenberg, Kurt-Mothes-Straße 2, D-06120 Halle/Saale (Germany)

2013-08-01

Highlights: • Polymer composites were prepared using a sol–gel synthesized BaTiO{sub 3}. • BaTiO{sub 3} surface hydroxyle groups act as linkers for surfactant molecules. • The effect of chemical adjustment between surfactant and polymer host is studied. • A positive effect of an additional dispersant was found. • Dielectric properties of the resulting composite films are presented. -- Abstract: We report on BaTiO{sub 3}–polymer composites as dielectrics for film capacitors. BaTiO{sub 3} was synthesized by a sol–gel soft-chemistry method leading to spherical nanoparticles with a high degree of surface hydroxyl groups which turned out to be important for the bonding of surfactant molecules. As surfactants, n-octylphosphonic acid and 2,3,4,5,6-pentafluorobenzyl phosphonic acid were used to inhibit particle agglomeration and to improve the wetting behaviour with the polymer. The phosphonic acid-coated BaTiO{sub 3} nanoparticles were dispersed in solutions of poly(vinylidefluoride-co-hexafluoropropylene). Composite films were prepared by the spin-coating technique. A systematic study was performed on the influence of varying oxide fractions, different surfactants and the effect of additional dispersion aids such as sodium dodecyl sulphate or BYK-W 9010 on the quality and dielectric properties of the films obtained. The chemical adjustment of the 2,3,4,5,6-pentaflourobenzyl phosphonic acid within the fluorinated organic host form a more uniform particle distribution and increase relative permittivity of the resulting composite material compared to the unflourinated surfactant. Additionally, an enhancement of the relative permittivity can be realized by adding of dispersants. These two components can increase the relative permittivity by factor 5 compared to the pure polymer material.

Microstickies agglomeration by electric field.

Science.gov (United States)

Du, Xiaotang Tony; Hsieh, Jeffery S

2016-01-01

Microstickies deposits on both paper machine and paper products when it agglomerates under step change in ionic strength, pH, temperature and chemical additives. These stickies increase the down time of the paper mill and decrease the quality of paper. The key property of microstickies is its smaller size, which leads to low removal efficiency and difficulties in measurement. Thus the increase of microstickies size help improve both removal efficiency and reduce measurement difficulty. In this paper, a new agglomeration technology based on electric field was investigated. The electric treatment could also increase the size of stickies particles by around 100 times. The synergetic effect between electric field treatment and detacky chemicals/dispersants, including polyvinyl alcohol, poly(diallylmethylammonium chloride) and lignosulfonate, was also studied.

Dispersion Forces

CERN Document Server

Buhmann, Stefan Yoshi

2012-01-01

In this book, a modern unified theory of dispersion forces on atoms and bodies is presented which covers a broad range of advanced aspects and scenarios. Macroscopic quantum electrodynamics is shown to provide a powerful framework for dispersion forces which allows for discussing general properties like their non-additivity and the relation between microscopic and macroscopic interactions. It is demonstrated how the general results can be used to obtain dispersion forces on atoms in the presence of bodies of various shapes and materials. Starting with a brief recapitulation of volume I, this volume II deals especially with bodies of irregular shapes, universal scaling laws, dynamical forces on excited atoms, enhanced forces in cavity quantum electrodynamics, non-equilibrium forces in thermal environments and quantum friction. The book gives both the specialist and those new to the field a thorough overview over recent results in the field. It provides a toolbox for studying dispersion forces in various contex...

Methods of synthesizing carbon-magnetite nanocomposites from renewable resource materials and application of same

Science.gov (United States)

Viswanathan, Tito

2014-07-29

A method of synthesizing carbon-magnetite nanocomposites. In one embodiment, the method includes the steps of (a) dissolving a first amount of an alkali salt of lignosulfonate in water to form a first solution, (b) heating the first solution to a first temperature, (c) adding a second amount of iron sulfate (FeSO.sub.4) to the first solution to form a second solution, (d) heating the second solution at a second temperature for a first duration of time effective to form a third solution of iron lignosulfonate, (e) adding a third amount of 1N sodium hydroxide (NaOH) to the third solution of iron lignosulfonate to form a fourth solution with a first pH level, (f) heating the fourth solution at a third temperature for a second duration of time to form a first sample, and (g) subjecting the first sample to a microwave radiation for a third duration of time effective to form a second sample containing a plurality of carbon-magnetite nanocomposites.

Quantification of abscisic acid in a single maize root

International Nuclear Information System (INIS)

Reymond, P.; Saugy, M.; Pilet, P.E.

1987-01-01

Quantitative analyses of abscisic acid in the elongating zone of a single maize root (Zea mays L. cv LG 11) were performed by gas chromatography-mass spectrometry using negative chemical ion ionization. Data showed that the more abscisic acid, the slower the growth, but a large dispersion of individual values was observed. We assume that abscisic acid is perhaps not correlated only to the growth rate. (author)

The dispersion of fine chitosan particles by beads-milling

Science.gov (United States)

Rochima, Emma; Utami, Safira; Hamdani, Herman; Azhary, Sundoro Yoga; Praseptiangga, Danar; Joni, I. Made; Panatarani, Camellia

2018-02-01

This research aimed to produce fine chitosan particles from a crab shell waste by beads-milling method by two different concentration of PEG as dispersing agent (150 and 300 wt. %). The characterization was performed to obtain the size and size distribution, the characteristics of functional groups and the degree of deacetylation. The results showed that the chitosan fine particles was obtained with a milling time 120 minutes with the best concentration of PEG 400 150 wt. %. The average particle size of the as-prepared suspension is 584 nm after addition of acetic acid solution (1%, v/v). Beads milling process did not change the glucosamine and N-acetylglucosamine content on chitosan structure which is indicated by degree of deacetylation higher than 70%. It was concluded that beads milling process can be applied to prepare chitosan fineparticles by proper adjustment in the milling time, pH and dosage of dispersing agent.

Moessbauer investigation of maghemite-based glycolic acid nanocomposite

International Nuclear Information System (INIS)

Santos, J. G.; Silveira, L. B.; Oliveira, A. C.; Garg, V. K.; Lacava, B. M.; Tedesco, A. C.; Morais, P. C.

2007-01-01

Transmission electron microscopy, X-ray diffraction and Moessbauer spectroscopy were used in the characterization of a nanocomposite containing magnetic nanoparticles dispersed in a glycolic acid-based template. Maghemite nanoparticles were identified as the iron oxide phase dispersed in the polymeric template. From the low-temperature Moessbauer data the amount of the iron-based, non-magnetic material at the nanoparticle surface was estimated as roughly one monolayer in thickness.

A review on thermophysical properties of nanoparticle dispersed phase change materials

International Nuclear Information System (INIS)

Kibria, M.A.; Anisur, M.R.; Mahfuz, M.H.; Saidur, R.; Metselaar, I.H.S.C.

2015-01-01

Highlights: • Thermo physical properties of PCM could be enhanced by dispersing nanoparticles. • Surface/physical properties of nanoparticle could affect the thermal properties of PCM. • CNT and CNF showed better performance to enhance the thermal properties of PCM. • Some predictions in NePCM literature needs further investigations. - Abstract: A review of current experimental studies on variations in thermophysical properties of phase change material (PCM) due to dispersion of nanoparticles is presented in this article. Dispersed carbon nanotubes/fiber and different metal/metal oxide nano particles in paraffin and fatty acids might be a solution to improve latent heat thermal storage performance. Thermophysical properties such as thermal conductivity, latent heat, viscosity and super cooling of phase change materials (PCM) could be changed for different physical properties of dispersed nanoparticle such as size, shape, concentration and surface properties. Among the nano particles, comparatively carbon nanotubes and carbon nano fiber have shown better performance in enhancing the thermal properties of PCM for their unique properties. The present review will focus on the studies that describe how the surface, chemical and physical properties of nanoparticle could affect the thermal properties of PCM with the help of available explanations in the literature

Theory of dispersive microlenses

Science.gov (United States)

Herman, B.; Gal, George

1993-01-01

A dispersive microlens is a miniature optical element which simultaneously focuses and disperses light. Arrays of dispersive mircolenses have potential applications in multicolor focal planes. They have a 100 percent optical fill factor and can focus light down to detectors of diffraction spot size, freeing up areas on the focal plane for on-chip analog signal processing. Use of dispersive microlenses allows inband color separation within a pixel and perfect scene registration. A dual-color separation has the potential for temperature discrimination. We discuss the design of dispersive microlenses and present sample results for efficient designs.

Cefuroxime axetil solid dispersions prepared using solution enhanced dispersion by supercritical fluids.

Science.gov (United States)

Jun, Seoung Wook; Kim, Min-Soo; Jo, Guk Hyun; Lee, Sibeum; Woo, Jong Soo; Park, Jeong-Sook; Hwang, Sung-Joo

2005-12-01

Cefuroxime axetil (CA) solid dispersions with HPMC 2910/PVP K-30 were prepared using solution enhanced dispersion by supercritical fluids (SEDS) in an effort to increase the dissolution rate of poorly water-soluble drugs. Their physicochemical properties in solid state were characterized by differential scanning calorimeter (DSC), powder X-ray diffraction (PXRD), Fourier transform infrared spectrometry (FT-IR) and scanning electron microscopy. No endothermic and characteristic diffraction peaks corresponding to CA were observed for the solid dispersions in DSC and PXRD. FTIR analysis demonstrated the presence of intermolecular hydrogen bonds between CA and HPMC 2910/PVP K-30 in solid dispersions, resulting in the formation of amorphous or non-crystalline CA. Dissolution studies indicated that the dissolution rates were remarkably increased in solid dispersions compared with those in the physical mixture and drug alone. In conclusion, an amorphous or non-crystalline CA solid dispersion prepared using SEDS could be very useful for the formulation of solid dosage forms.

Metal dispersion in groundwater in an area with natural and processed black shale - Nationwide perspective and comparison with acid sulfate soils

International Nuclear Information System (INIS)

Lavergren, Ulf; Astroem, Mats E.; Falk, Helena; Bergbaeck, Bo

2009-01-01

Black shale is often rich in sulfides and trace elements, and is thus a potential environmental threat in a manner similar to acid sulfate soils and active or abandoned sulfide mines. This study aims at characterising how exposed and processed (mined and burnt) black shale (alum shale) in Degerhamn, SE Sweden, affects the chemistry (Al, As, Ba, Cd, Ca, Cr, Co, Cu, Fe, Pb, Mg, Mn, Mo, Ni, K, Si, Na, Sr, S, U, V and Zn) of the groundwater. There were large variations in groundwater chemistry between nearby sampling points, while the temporal variations generally were small. Acidic groundwater (around pH 4), found in deposits of burnt and carbonate-poor shale where the conditions for sulfide oxidation were favourable, was strongly elevated in Al, U and several chalcophilic metals (Cd, Co, Cu, Ni and Zn). Cadmium and U were also, together with Mo, abundant in many of the near-neutral waters, both in the non-mined black shale bedrock and in the deposits of burnt shale. An extrapolation to a national level suggests that the dispersion of Ni from naturally occurring black shale is similar to that from anthropogenic point sources, while for Cd and As it is assessed to be approximately one tenth of that from point sources. The processed shale was, however, a much larger source of metals than the black shale bedrock itself, showing this material's potential as a massive supplier of metals to the aquatic environment. A comparison of waters in contact with the processed Cambrian-Ordovician black shale in Degerhamn and acid sulfate soils of the region shows that these two sulfide-bearing materials, in many respects very different, delivers basically the same suite of trace elements to the aquatic environment. This has implications for environmental planning and protection in areas where these types of materials exist

Wave-equation dispersion inversion

KAUST Repository

Li, Jing; Feng, Zongcai; Schuster, Gerard T.

2016-01-01

We present the theory for wave-equation inversion of dispersion curves, where the misfit function is the sum of the squared differences between the wavenumbers along the predicted and observed dispersion curves. The dispersion curves are obtained

Preparation and Characterization of Waterborne Polyurethaneurea Composed of Dimer Fatty Acid Polyester Polyol

Directory of Open Access Journals (Sweden)

2006-01-01

Full Text Available A series of polyurethaneurea (PUU aqueous dispersions, which were stable at ambient temperature for more than 1 year, were prepared with C 36 -dimer-fatty-acid-based polyester polyol, isophorone diisocyanate, dimethylol propionic acid, and ethylenediamine. The particle size of all these PUU (DPU aqueous dispersions ( <100 nm was less than that of comparable specimens, that is, poly-(neopentyl glycol adipate polyester-polyol-based PUU (APU aqueous dispersions, and the polydispersity index was very narrow ( ≤1.13 . The films prepared with the DPU aqueous dispersions exhibited excellent waterproof performance, such as low amount of water absorption (1.3 wt%, and good mechanical properties (hardness and tensile strength, resulting from the strong hydrogen bonding in urea carbonyl groups and the perfect ordered structure of hard segments compared with those prepared with the APU aqueous dispersions. The surface hydrophobicity of the films prepared with modified DPU aqueous dispersions, which were modified with a fluorinated polyacrylate emulsion, was excellent, as the water contact angle on the surface of such films rose up to 100. The mechanical properties of such modified DPU films were further enhanced.

Optimization of folic acid nano-emulsification and encapsulation by maltodextrin-whey protein double emulsions.

Science.gov (United States)

Assadpour, Elham; Maghsoudlou, Yahya; Jafari, Seid-Mahdi; Ghorbani, Mohammad; Aalami, Mehran

2016-05-01

Due to susceptibility of folic acid like many other vitamins to environmental and processing conditions, it is necessary to protect it by highly efficient methods such as micro/nano-encapsulation. Our aim was to prepare and optimize real water in oil nano-emulsions containing folic acid by a low energy (spontaneous) emulsification technique so that the final product could be encapsulated within maltodextrin-whey protein double emulsions. A non ionic surfactant (Span 80) was used for making nano-emulsions at three dispersed phase/surfactant ratios of 0.2, 0.6, and 1.0. Folic acid content was 1.0, 2.0, and 3.0mg/mL of dispersed phase by a volume fraction of 5.0, 8.5, and 12%. The final optimum nano-emulsion formulation with 12% dispersed phase, a water to surfactant ratio of 0.9 and folic acid content of 3mg/mL in dispersed phase was encapsulated within maltodextrin-whey protein double emulsions. It was found that the emulsification time for preparing nano-emulsions was between 4 to 16 h based on formulation variables. Droplet size decreased at higher surfactant contents and final nano-emulsions had a droplet size<100 nm. Shear viscosity was higher for those formulations containing more surfactant. Our results revealed that spontaneous method could be used successfully for preparing stable W/O nano-emulsions containing folic acid. Copyright © 2016 Elsevier B.V. All rights reserved.

Lanthanide Phytanates: Liquid-Crystalline Phase Behavior, Colloidal Particle Dispersions, and Potential as Medical Imaging Agents

Energy Technology Data Exchange (ETDEWEB)

Conn, Charlotte E.; Panchagnula, Venkateswarlu; Weerawardena, Asoka; Waddington, Lynne J.; Kennedy, Danielle F.; Drummond, Calum J. (CSIRO/MHT); (CSIRO/MSE)

2010-08-23

Lanthanide salts of phytanic acid, an isoprenoid-type amphiphile, have been synthesized and characterized. Elemental analysis and FTIR spectroscopy were used to confirm the formed product and showed that three phytanate anions are complexed with one lanthanide cation. The physicochemical properties of the lanthanide phytanates were investigated using DSC, XRD, SAXS, and cross-polarized optical microscopy. Several of the hydrated salts form a liquid-crystalline hexagonal columnar mesophase at room temperature, and samarium(III) phytanate forms this phase even in the absence of water. Select lanthanide phytanates were dispersed in water, and cryo-TEM images indicate that some structure has been retained in the dispersed phase. NMR relaxivity measurements were conducted on these systems. It has been shown that a particulate dispersion of gadolinium(III) phytanate displays proton relaxivity values comparable to those of a commercial contrast agent for magnetic resonance imaging and a colloidal dispersion of europium(III) phytanate exhibits the characteristics of a fluorescence imaging agent.

Lanthanide Phytanates: Liquid-Crystalline Phase Behavior, Colloidal Particle Dispersions, and Potential as Medical Imaging Agents

International Nuclear Information System (INIS)

Conn, Charlotte E.; Panchagnula, Venkateswarlu; Weerawardena, Asoka; Waddington, Lynne J.; Kennedy, Danielle F.; Drummond, Calum J.

2010-01-01

Lanthanide salts of phytanic acid, an isoprenoid-type amphiphile, have been synthesized and characterized. Elemental analysis and FTIR spectroscopy were used to confirm the formed product and showed that three phytanate anions are complexed with one lanthanide cation. The physicochemical properties of the lanthanide phytanates were investigated using DSC, XRD, SAXS, and cross-polarized optical microscopy. Several of the hydrated salts form a liquid-crystalline hexagonal columnar mesophase at room temperature, and samarium(III) phytanate forms this phase even in the absence of water. Select lanthanide phytanates were dispersed in water, and cryo-TEM images indicate that some structure has been retained in the dispersed phase. NMR relaxivity measurements were conducted on these systems. It has been shown that a particulate dispersion of gadolinium(III) phytanate displays proton relaxivity values comparable to those of a commercial contrast agent for magnetic resonance imaging and a colloidal dispersion of europium(III) phytanate exhibits the characteristics of a fluorescence imaging agent.

Seed dispersal in fens

NARCIS (Netherlands)

Middleton, Beth; van Diggelen, Rudy; Jensen, Kai

Question: How does seed dispersal reduce fen isolation and contribute to biodiversity? Location: European and North American fens. Methods: This paper reviews the literature on seed dispersal to fens. Results: Landscape fragmentation may reduce dispersal opportunities thereby isolating fens and

Chemical countermeasures: Dispersants overview of dispersant use (including application) and research issues

International Nuclear Information System (INIS)

Butler, J.N.

1992-01-01

I will attempt in twenty minutes to summarize the state of research on oil spill dispersants as I perceive it. The expertise I bring to this task includes 20 years of experience with the fate and effects of petroleum in the marine environment, including participation in the 1973 and 1981 NRC studies and three years as chairman of the NRC committee on oil spill dispersants. I More recently I served on a committee of the International Maritime Organization which reviewed the open-quotes Impact of oil and related chemicals and wastes on the marine environment.close quotes That report will be published this year. However, my statements in this paper are not made as a representative of either NRC or IMO. They are my own interpretation of scientific literature cited in the above reviews. Dispersants are chemical formulations, which include surface active agents, designed to decrease the interfacial tension between oil and water. Because the first attempts to disperse oil on a large scale, at the Torrey Canyon spill of 1967, used highly toxic degreasing agents, dispersants have an undeserved reputation for toxicity. In fact, for twenty years dispersant formulations have been developed with an emphasis on reducing their toxicity to marine life. The dispersal of oil in water has been documented in the laboratory by dozens of papers (see references in NRC 1989, pp 70-79), and in the field by dozens of studies (NRC 1989, pp 165- 193). The toxicity of commercial dispersant formulations (NRC 1989, pp 81-123) and dispersed oil (NRC 1989, pp 123-147) has been tested on a wide variety of marine organisms ranging from algae to salmonid fishes. The NRC review has been updated by the IMO/GESAMP (1992) study, but the conclusions remain unchanged

Dispersing powders in liquids

CERN Document Server

Nelson, RD

1988-01-01

This book provides powder technologists with laboratory procedures for selecting dispersing agents and preparing stable dispersions that can then be used in particle size characterization instruments. Its broader goal is to introduce industrial chemists and engineers to the phenomena, terminology, physical principles, and chemical considerations involved in preparing and handling dispersions on a commercial scale. The book introduces novices to: - industrial problems due to improper degree of dispersion; - the nomenclature used in describing particles; - the basic physica

Seed dispersal in fens

Science.gov (United States)

Middleton, B.; Van Diggelen, R.; Jensen, K.

2006-01-01

Question: How does seed dispersal reduce fen isolation and contribute to biodiversity? Location: European and North American fens. Methods: This paper reviews the literature on seed dispersal to fens. Results: Landscape fragmentation may reduce dispersal opportunities thereby isolating fens and reducing genetic exchange. Species in fragmented wetlands may have lower reproductive success, which can lead to biodiversity loss. While fens may have always been relatively isolated from each other, they have become increasingly fragmented in modern times within agricultural and urban landscapes in both Europe and North America. Dispersal by water, animals and wind has been hampered by changes related to development in landscapes surrounding fens. Because the seeds of certain species are long-lived in the seed bank, frequent episodes of dispersal are not always necessary to maintain the biodiversity of fens. However, of particular concern to restoration is that some dominant species, such as the tussock sedge Carex stricta, may not disperse readily between fens. Conclusions: Knowledge of seed dispersal can be used to maintain and restore the biodiversity of fens in fragmented landscapes. Given that development has fragmented landscapes and that this situation is not likely to change, the dispersal of seeds might be enhanced by moving hay or cattle from fens to damaged sites, or by reestablishing lost hydrological connections. ?? IAVS; Opulus Press.

Signals can trump rewards in attracting seed-dispersing ants.

Directory of Open Access Journals (Sweden)

Kyle M Turner

Full Text Available Both rewards and signals are important in mutualisms. In myrmecochory, or seed dispersal by ants, the benefits to plants are relatively well studied, but less is known about why ants pick up and move seeds. We examined seed dispersal by the ant Aphaenogaster rudis of four co-occurring species of plants, and tested whether morphology, chemical signaling, or the nutritional quality of fatty seed appendages called elaiosomes influenced dispersal rates. In removal trials, ants quickly collected diaspores (seeds plus elaiosomes of Asarum canadense, Trillium grandiflorum, and Sanguinaria canadensis, but largely neglected those of T. erectum. This discrepancy was not explained by differences in the bulk cost-benefit ratio, as assessed by the ratio of seed to elaiosome mass. We also provisioned colonies with diaspores from one of these four plant species or no diaspores as a control. Colonies performed best when fed S. canadensis diaspores, worst when fed T. grandiflorum, and intermediately when fed A. canadense, T. erectum, or no diaspores. Thus, the nutritional rewards in elaiosomes affected colony performance, but did not completely predict seed removal. Instead, high levels of oleic acid in T. grandiflorum elaiosomes may explain why ants disperse these diaspores even though they reduce ant colony performance. We show for the first time that different elaiosome-bearing plants provide rewards of different quality to ant colonies, but also that ants appear unable to accurately assess reward quality when encountering seeds. Instead, we suggest that signals can trump rewards as attractants of ants to seeds.

Wave-equation dispersion inversion

KAUST Repository

Li, Jing

2016-12-08

We present the theory for wave-equation inversion of dispersion curves, where the misfit function is the sum of the squared differences between the wavenumbers along the predicted and observed dispersion curves. The dispersion curves are obtained from Rayleigh waves recorded by vertical-component geophones. Similar to wave-equation traveltime tomography, the complicated surface wave arrivals in traces are skeletonized as simpler data, namely the picked dispersion curves in the phase-velocity and frequency domains. Solutions to the elastic wave equation and an iterative optimization method are then used to invert these curves for 2-D or 3-D S-wave velocity models. This procedure, denoted as wave-equation dispersion inversion (WD), does not require the assumption of a layered model and is significantly less prone to the cycle-skipping problems of full waveform inversion. The synthetic and field data examples demonstrate that WD can approximately reconstruct the S-wave velocity distributions in laterally heterogeneous media if the dispersion curves can be identified and picked. The WD method is easily extended to anisotropic data and the inversion of dispersion curves associated with Love waves.

Spurious dispersion effects at FLASH

International Nuclear Information System (INIS)

Prat, Eduard

2009-07-01

The performance of the Free-Electron Laser (FEL) process imposes stringent demands on the transverse trajectory and size of the electron beam. Since transverse dispersion changes off-energy particle trajectories and increases the effective beam size, dispersion must be controlled. This thesis treats the concept of dispersion in linacs, and analyses the impact of dispersion on the electron beam and on the FEL process. It presents generation mechanisms for spurious dispersion, quantifying its importance for FLASH (Free-electron Laser in Hamburg) and the XFEL (European X-ray Free-Electron Laser). A method for measuring and correcting dispersion and its implementation in FLASH is described. Experiments of dispersion e ects on the transverse beam quality and on the FEL performance are presented. (orig.)

Spurious dispersion effects at FLASH

Energy Technology Data Exchange (ETDEWEB)

Prat, Eduard

2009-07-15

The performance of the Free-Electron Laser (FEL) process imposes stringent demands on the transverse trajectory and size of the electron beam. Since transverse dispersion changes off-energy particle trajectories and increases the effective beam size, dispersion must be controlled. This thesis treats the concept of dispersion in linacs, and analyses the impact of dispersion on the electron beam and on the FEL process. It presents generation mechanisms for spurious dispersion, quantifying its importance for FLASH (Free-electron Laser in Hamburg) and the XFEL (European X-ray Free-Electron Laser). A method for measuring and correcting dispersion and its implementation in FLASH is described. Experiments of dispersion e ects on the transverse beam quality and on the FEL performance are presented. (orig.)

Metapopulation extinction risk: dispersal's duplicity.

Science.gov (United States)

Higgins, Kevin

2009-09-01

Metapopulation extinction risk is the probability that all local populations are simultaneously extinct during a fixed time frame. Dispersal may reduce a metapopulation's extinction risk by raising its average per-capita growth rate. By contrast, dispersal may raise a metapopulation's extinction risk by reducing its average population density. Which effect prevails is controlled by habitat fragmentation. Dispersal in mildly fragmented habitat reduces a metapopulation's extinction risk by raising its average per-capita growth rate without causing any appreciable drop in its average population density. By contrast, dispersal in severely fragmented habitat raises a metapopulation's extinction risk because the rise in its average per-capita growth rate is more than offset by the decline in its average population density. The metapopulation model used here shows several other interesting phenomena. Dispersal in sufficiently fragmented habitat reduces a metapopulation's extinction risk to that of a constant environment. Dispersal between habitat fragments reduces a metapopulation's extinction risk insofar as local environments are asynchronous. Grouped dispersal raises the effective habitat fragmentation level. Dispersal search barriers raise metapopulation extinction risk. Nonuniform dispersal may reduce the effective fraction of suitable habitat fragments below the extinction threshold. Nonuniform dispersal may make demographic stochasticity a more potent metapopulation extinction force than environmental stochasticity.

Exopolysaccharides produced by lactic acid bacteria

NARCIS (Netherlands)

Caggianiello, Graziano; Kleerebezem, Michiel; Spano, Giuseppe

2016-01-01

A wide range of lactic acid bacteria (LAB) is able to produce capsular or extracellular polysaccharides, with various chemical compositions and properties. Polysaccharides produced by LAB alter the rheological properties of the matrix in which they are dispersed, leading to typically viscous and

Pd nanoparticles supported on functionalized multi-walled carbon nanotubes (MWCNTs) and electrooxidation for formic acid

Energy Technology Data Exchange (ETDEWEB)

Yang, Sudong; Mi, Hongyu; Ye, Xiangguo [Institute of Applied Chemistry, Xinjiang University, Urumqi 830046 (China); Zhang, Xiaogang [College of Material Science and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)

2008-01-03

To improve the utilization and activity of anodic catalysts for formic acid electrooxidation, palladium (Pd) particles were loaded on the MWCNTs, which were functionalized in a mixture of 96% sulfuric acid and 4-aminobenzenesulfonic acid, using sodium nitrite to produce intermediate diazonium salts from substituted anilines. The composition, particle size, and crystallinity of the Pd/f-MWCNTs catalysts were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and energy dispersive spectroscopy (EDS) measurements. The electrocatalytic properties of the Pd/f-MWCNTs catalysts for formic acid oxidation were investigated by cyclic voltammetry (CV) and linear sweep voltammetry (LSV) in 0.5 mol L{sup -1} H{sub 2}SO{sub 4} solution. The results demonstrated that the catalytic activity was greatly enhanced due to the improved water-solubility and dispersion of the f-MWCNTs, which were facile to make the small particle size (3.8 nm) and uniform dispersion of Pd particles loading on the surface of the MWCNTs. In addition, the functionalized MWCNTs with benzenesulfonic group can provide benzenesulfonic anions in aqueous solution, which may combine with hydrogen cation and then promote the oxidation of formic acid reactive intermediates. So the Pd/f-MWCNTs composites showed excellent electrocatalytic activity for formic acid oxidation. (author)

Dispersion stability of thermal nanofluids

Directory of Open Access Journals (Sweden)

Fan Yu

2017-10-01

Full Text Available Thermal nanofluids, the engineered fluids with dispersed functional nanoparticles, have exhibited extraordinary thermophysical properties and added functionalities, and thus have enabled a broad range of important applications. The poor dispersion stability of thermal nanofluids, however, has been considered as a long-existing issue that limits their further development and practical application. This review overviews the recent efforts and progresses in improving the dispersion stability of thermal nanofluids such as mechanistic understanding of dispersion behavior of nanofluids, examples of both water-based and oil-based nanofluids, strategies to stabilize nanofluids, and characterization techniques for dispersion behavior of nanofluids. Finally, on-going research needs, and possible solutions to research challenges and future research directions in exploring stably dispersed thermal nanofluids are discussed. Keywords: Thermal nanofluids, Dispersion, Aggregation, Electrostatic stabilization, Steric stabilization

Luminescence screening of enrofloxacin and ciprofloxacin residues in swine liver after dispersive liquid - liquid microextraction cleanup

Science.gov (United States)

A rapid luminescence method was developed to screen residues of enrofloxacin (ENRO) and its metabolite, ciprofloxacin (CIPRO), in swine liver. Target analytes were extracted in acetonitrile-2.5% trifluoroacetic acid-NaCl, cleaned up by dispersive liquid-liquid microextraction (DLLME), and finally de...

Hydrodynamic disperser

Energy Technology Data Exchange (ETDEWEB)

Bulatov, A.I.; Chernov, V.S.; Prokopov, L.I.; Proselkov, Yu.M.; Tikhonov, Yu.P.

1980-01-15

A hydrodynamic disperser is suggested which contains a housing, slit nozzles installed on a circular base arranged opposite from each other, resonators secured opposite the nozzle and outlet sleeve. In order to improve the effectiveness of dispersion by throttling the flow, each resonator is made in the form of a crimped plate with crimpings that decrease in height in a direction towards the nozzle.

Simultaneous pore enlargement and introduction of highly dispersed Fe active sites in MSNs for enhanced catalytic activity

International Nuclear Information System (INIS)

Gu Jinlou; Dong Xu; Elangovan, S.P.; Li Yongsheng; Zhao Wenru; Iijima, Toshio; Yamazaki, Yasuo; Shi Jianlin

2012-01-01

An effective post-hydrothermal treatment strategy has been developed to dope highly dispersed iron catalytical centers into the framework of mesoporous silica, to keep the particle size in nanometric scale, and in the meanwhile, to expand the pore size of the synthesized mesoporous silica nanoparticles (MSNs). Characterization techniques such as XRD, BET, SEM and TEM support that the synthesized samples are long period ordered with particles size about 100 nm and a relatively large pore size of ca. 3.5 nm. UV–vis, XPS and EPR measurements demonstrate that the introduced iron active centers are highly dispersed in a coordinatively unsaturated status. NH 3 -TPD verifies that the acid amount of iron-doped MSNs is quite high. The synthesized nanocatalysts show an excellent catalytic performance for benzylation of benzene by benzyl chloride, and they present relatively higher yield and selectivity to diphenylmethane with a lower iron content and much shorter reaction time. - Graphical abstract: Uniform MSNs with iron active centers and large pore size have been prepared by a newly developed strategy, which demonstrates enhanced catalytic performance for benzylation of benzene by benzyl chloride. Highlights: ► Iron species were introduced into the framework of mesoporous silica nanoparticles with uniform dispersion. ► The pore sizes of the synthesized nanocatalysts were expanded. ► The acidic site quantities were quite high and the acidic centers were accessible. ► The nanocatalysts presented higher yield and selectivity to diphenylmethane with significantly lower Fe content.

Parameters estimation for amino acids adsorption in a fixed bed by moment analysis

Directory of Open Access Journals (Sweden)

M.A. Cremasco

2001-06-01

Full Text Available Equilibrium constant and mass transfer parameters are needed for the study of amino acid separation in any process involving adsorption in fixed beds. The adsorption constants, effective diffusion coefficients, and axial dispersion coefficients for two amino acids, L-phenylalanine (Phe and L-tyrosine (Tyr, are determined from a series of pulse tests in a fixed bed packed with PVP (poly-4-vinylpyridine resin. Total bed voidage at different flow rates is estimated from NaCl pulse test data. The effective pore diffusivities of Phe, Tyr, and NaCl are estimated from moment analysis of pulse data. A detailed rate model is then solved numerically and adsorption constants, effective diffusion coefficients, axial dispersion coefficients are determined by moment analysis and compared with the pulse data. The advantage of this method is that the effective intraparticle diffusivities can be determined without the influence of extracolumn dispersion or intracolumn axial dispersion effects.

Dispersal and metapopulation stability

Directory of Open Access Journals (Sweden)

Shaopeng Wang

2015-10-01

Full Text Available Metapopulation dynamics are jointly regulated by local and spatial factors. These factors may affect the dynamics of local populations and of the entire metapopulation differently. Previous studies have shown that dispersal can stabilize local populations; however, as dispersal also tends to increase spatial synchrony, its net effect on metapopulation stability has been controversial. Here we present a simple metapopulation model to study how dispersal, in interaction with other spatial and local processes, affects the temporal variability of metapopulations in a stochastic environment. Our results show that in homogeneous metapopulations, the local stabilizing and spatial synchronizing effects of dispersal cancel each other out, such that dispersal has no effect on metapopulation variability. This result is robust to moderate heterogeneities in local and spatial parameters. When local and spatial dynamics exhibit high heterogeneities, however, dispersal can either stabilize or destabilize metapopulation dynamics through various mechanisms. Our findings have important theoretical and practical implications. We show that dispersal functions as a form of spatial intraspecific mutualism in metapopulation dynamics and that its effect on metapopulation stability is opposite to that of interspecific competition on local community stability. Our results also suggest that conservation corridors should be designed with appreciation of spatial heterogeneities in population dynamics in order to maximize metapopulation stability.

OXIDATION AND SULFOMETHYLATION OF ALKALI-EXTRACTED LIGNIN FROM CORN STALK

Directory of Open Access Journals (Sweden)

Huiran Wu,

2012-05-01

Full Text Available A lignosulfonate was prepared from alkali-extracted corn stalk lignin (AEL by oxidation under mild conditions and sulfomethylation. The oxidized AEL exhibited lower molecular weight, narrower molecular weight distribution, and higher phenolic hydroxyl content than AEL, demonstrating that oxidized AEL was more reactive than those before oxidation. The content of sulfonic groups was significantly increased with the increase in sodium sulphite to AEL ratio, while the content slightly decreased when the ratio was above 1:1. During the sulfomethylation, the content of sulfonic groups increased with time and then achieved a constant level with the increase in time. The content of sulfonic groups reached 1.29 mmol/g, the maximum value, at 5 h and a sodium sulphite to AEL ratio of 1:1. The solubility of AEL was obviously improved by sulfomethylation with the increase in the content of sulfonic groups. The surface activity of AEL was improved after sulfomethylation. The sulfomethylation products exhibited good dispersibility and showed potential for use as a dye dispersant.

Dispersion of multi-walled carbon nanotubes in biocompatible dispersants

International Nuclear Information System (INIS)

Piret, J.-P.; Detriche, S.; Vigneron, R.; Vankoningsloo, S.; Rolin, S.; Mejia Mendoza, J. H.; Masereel, B.; Lucas, S.; Delhalle, J.; Luizi, F.; Saout, C.; Toussaint, O.

2010-01-01

Owing to their phenomenal electrical and mechanical properties, carbon nanotubes (CNT) have been an area of intense research since their discovery in 1991. Different applications for these nanoparticles have been proposed, among others, in electronics and optics but also in the medical field. In parallel, emerging studies have suggested potential toxic effects of CNT while others did not, generating some conflicting outcomes. These discrepancies could be, in part, due to different suspension approaches used and to the agglomeration state of CNT in solution. In this study, we described a standardized protocol to obtain stable CNT suspensions, using two biocompatible dispersants (Pluronic F108 and hydroxypropylcellulose) and to estimate the concentration of CNT in solution. CNT appear to be greatly individualized in these two dispersants with no detection of remaining bundles or agglomerates after sonication and centrifugation. Moreover, CNT remained perfectly dispersed when added to culture medium used for in vitro cell experiments. We also showed that Pluronic F108 is a better dispersant than hydroxypropylcellulose. In conclusion, we have developed a standardized protocol using biocompatible surfactants to obtain reproducible and stable multi-walled carbon nanotubes suspensions which can be used for in vitro or in vivo toxicological studies.

Surfactive stabilization of multi-walled carbon nanotube dispersions with dissolved humic substances

Energy Technology Data Exchange (ETDEWEB)

Chappell, Mark A. [Environmental Laboratory, Engineering Research and Development Center, US Army Corps of Engineers, 3909 Halls Ferry Road, Vicksburg, MS 39180 (United States)], E-mail: mark.a.chappell@usace.army.mil; George, Aaron J.; Dontsova, Katerina M.; Porter, Beth E. [SpecPro, Inc., 4815 Bradford Drive, Suite 201, Huntsville, AL 35805 (United States); Price, Cynthia L. [Environmental Laboratory, Engineering Research and Development Center, US Army Corps of Engineers, 3909 Halls Ferry Road, Vicksburg, MS 39180 (United States); Zhou Pingheng; Morikawa, Eizi [J. Bennett Johnston Sr. Center for Advanced Microstructures and Devices, Louisiana State University, 6980 Jefferson Highway, Baton Rouge, LA 70806 (United States); Kennedy, Alan J.; Steevens, Jeffery A. [Environmental Laboratory, Engineering Research and Development Center, US Army Corps of Engineers, 3909 Halls Ferry Road, Vicksburg, MS 39180 (United States)

2009-04-15

Soil humic substances (HS) stabilize carbon nanotube (CNT) dispersions, a mechanism we hypothesized arose from the surfactive nature of HS. Experiments dispersing multi-walled CNT in solutions of dissolved Aldrich humic acid (HA) or water-extractable Catlin soil HS demonstrated enhanced stability at 150 and 300 mg L{sup -1} added Aldrich HA and Catlin HS, respectively, corresponding with decreased CNT mean particle diameter (MPD) and polydispersivity (PD) of 250 nm and 0.3 for Aldrich HA and 450 nm and 0.35 for Catlin HS. Analogous trends in MPD and PD were observed with addition of the surfactants Brij 35, Triton X-405, and SDS, corresponding to surfactant sorption maximum. NEXAFS characterization showed that Aldrich HA contained highly surfactive domains while Catlin soil possessed a mostly carbohydrate-based structure. This work demonstrates that the chemical structure of humic materials in natural waters is directly linked to their surfactive ability to disperse CNT released into the environment. - Suspensions of multi-walled carbon nanotubes are stabilized by relatively low concentrations of dissolved humic substances in solution through surfactive mechanisms.

Surfactive stabilization of multi-walled carbon nanotube dispersions with dissolved humic substances

International Nuclear Information System (INIS)

Chappell, Mark A.; George, Aaron J.; Dontsova, Katerina M.; Porter, Beth E.; Price, Cynthia L.; Zhou Pingheng; Morikawa, Eizi; Kennedy, Alan J.; Steevens, Jeffery A.

2009-01-01

Soil humic substances (HS) stabilize carbon nanotube (CNT) dispersions, a mechanism we hypothesized arose from the surfactive nature of HS. Experiments dispersing multi-walled CNT in solutions of dissolved Aldrich humic acid (HA) or water-extractable Catlin soil HS demonstrated enhanced stability at 150 and 300 mg L -1 added Aldrich HA and Catlin HS, respectively, corresponding with decreased CNT mean particle diameter (MPD) and polydispersivity (PD) of 250 nm and 0.3 for Aldrich HA and 450 nm and 0.35 for Catlin HS. Analogous trends in MPD and PD were observed with addition of the surfactants Brij 35, Triton X-405, and SDS, corresponding to surfactant sorption maximum. NEXAFS characterization showed that Aldrich HA contained highly surfactive domains while Catlin soil possessed a mostly carbohydrate-based structure. This work demonstrates that the chemical structure of humic materials in natural waters is directly linked to their surfactive ability to disperse CNT released into the environment. - Suspensions of multi-walled carbon nanotubes are stabilized by relatively low concentrations of dissolved humic substances in solution through surfactive mechanisms

pH dependence of the properties of waterborne pressure-sensitive adhesives containing acrylic acid.

Science.gov (United States)

Wang, Tao; Canetta, Elisabetta; Weerakkody, Tecla G; Keddie, Joseph L; Rivas, Urko

2009-03-01

Polymer colloids are often copolymerized with acrylic acid monomers in order to impart colloidal stability. Here, the effects of the pH on the nanoscale and macroscopic adhesive properties of waterborne poly(butyl acrylate-co-acrylic acid) films are reported. In films cast from acidic colloidal dispersions, hydrogen bonding between carboxylic acid groups dominates the particle-particle interactions, whereas ionic dipolar interactions are dominant in films cast from basic dispersions. Force spectroscopy using an atomic force microscope and macroscale mechanical measurements show that latex films with hydrogen-bonding interactions have lower elastic moduli and are more deformable. They yield higher adhesion energies. On the other hand, in basic latex, ionic dipolar interactions increase the moduli of the dried films. These materials are stiffer and less deformable and, consequently, exhibit lower adhesion energies. The rate of water loss from acidic latex is slower, perhaps because of hydrogen bonding with the water. Therefore, although acid latex offers greater adhesion, there is a limitation in the film formation.

Importance of dispersal and thermal environment for mycorrhizal communities: lessons from Yellowstone National Park.

Science.gov (United States)

Lekberg, Ylva; Meadow, James; Rohr, Jason R; Redecker, Dirk; Zabinski, Catherine A

2011-06-01

The relative importance of dispersal and niche restrictions remains a controversial topic in community ecology, especially for microorganisms that are often assumed to be ubiquitous. We investigated the impact of these factors for the community assembly of the root-symbiont arbuscular mycorrhizal fungi (AMF) by sampling roots from geothermal and nonthermal grasslands in Yellowstone National Park (YNP), followed by sequencing and RFLP of AMF ribosomal DNA. With the exception of an apparent generalist RFLP type closely related to Glomus intraradices, a distance-based redundancy analysis indicated that the AMF community composition correlated with soil pH or pH-driven changes in soil chemistry. This was unexpected, given the large differences in soil temperature and plant community composition between the geothermal and nonthermal grasslands. RFLP types were found in either the acidic geothermal grasslands or in the neutral to alkaline grasslands, one of which was geothermal. The direct effect of the soil chemical environment on the distribution of two AMF morphospecies isolated from acidic geothermal grasslands was supported in a controlled greenhouse experiment. Paraglomus occultum and Scutellospora pellucida were more beneficial to plants and formed significantly more spores when grown in acidic than in alkaline soil. Distance among grasslands, used as an estimate of dispersal limitations, was not a significant predictor of AMF community similarity within YNP, and most fungal taxa may be part of a metacommunity. The isolation of several viable AMF taxa from bison feces indicates that wide-ranging bison could be a vector for at least some RFLP types among grasslands within YNP. In support of classical niche theory and the Baas-Becking hypothesis, our results suggest that AMF are not limited by dispersal at the scale of YNP, but that the soil environment appears to be the primary factor affecting community composition and distribution.

Tracer dispersion - experiment and CFD

International Nuclear Information System (INIS)

Zitny, R.

2004-01-01

Description of tracer distribution by means of dispersion models is a method successfully used in process engineering for fifty years. Application of dispersion models in reactor engineering for characterization of flows in column apparatus, heat exchangers, etc. is summarized and experimental tracer techniques as well as CFD methods for dispersion coefficients evaluation are discussed. Possible extensions of thermal axial dispersion model (ADM) and a core-wall ADM model suitable for description of tracer dispersion in laminar flows are suggested as well as CFD implementation as 1D finite elements. (author)

Military jet pilots have higher p-wave dispersions compared to the transport aircraft aircrew

Directory of Open Access Journals (Sweden)

Mustafa Çakar

2016-08-01

Full Text Available Objectives: For the purpose of flight safety military aircrew must be healthy. P-wave dispersion (PWD is the p-wave length difference in an electrocardiographic (ECG examination and represents the risk of developing atrial fibrillation. In the study we aimed at investigating PWD in healthy military aircrew who reported for periodical examinations. Material and Methods: Seventy-five asymptomatic military aircrew were enrolled in the study. All the subjects underwent physical, radiologic and biochemical examinations, and a 12-lead electrocardiography. P-wave dispersions were calculated. Results: The mean age of the study participants was 36.15±8.97 years and the mean p-wave duration was 100.8±12 ms in the whole group. Forty-seven subjects were non-pilot aircrew, and 28 were pilots. Thirteen study subjects were serving in jets, 49 in helicopters, and 13 were transport aircraft pilots. Thirty-six of the helicopter and 11 of the transport aircraft aircrew were non-pilot aircrew. P-wave dispersion was the lowest in the transport aircraft aircrew, and the highest in jet pilots. P-wave dispersions were similar in the pilots and non-pilot aircrew. Twenty-three study subjects were overweight, 19 had thyroiditis, 26 had hepatosteatosis, 4 had hyperbilirubinemia, 2 had hypertension, and 5 had hyperlipidemia. The PWD was significantly associated with thyroid-stimulating hormone (TSH levels. Serum uric acid levels were associated with p-wave durations. Serum TSH levels were the most important predictor of PWD. Conclusions: When TSH levels were associated with PWD, uric acid levels were associated with p-wave duration in the military aircrew. The jet pilots had higher PWDs. These findings reveal that military jet pilots may have a higher risk of developing atrial fibrillation, and PWD should be recorded during periodical examinations.

Strongly coupled dispersed two-phase flows; Ecoulements diphasiques disperses fortement couples

Energy Technology Data Exchange (ETDEWEB)

Zun, I.; Lance, M.; Ekiel-Jezewska, M.L.; Petrosyan, A.; Lecoq, N.; Anthore, R.; Bostel, F.; Feuillebois, F.; Nott, P.; Zenit, R.; Hunt, M.L.; Brennen, C.E.; Campbell, C.S.; Tong, P.; Lei, X.; Ackerson, B.J.; Asmolov, E.S.; Abade, G.; da Cunha, F.R.; Lhuillier, D.; Cartellier, A.; Ruzicka, M.C.; Drahos, J.; Thomas, N.H.; Talini, L.; Leblond, J.; Leshansky, A.M.; Lavrenteva, O.M.; Nir, A.; Teshukov, V.; Risso, F.; Ellinsen, K.; Crispel, S.; Dahlkild, A.; Vynnycky, M.; Davila, J.; Matas, J.P.; Guazelli, L.; Morris, J.; Ooms, G.; Poelma, C.; van Wijngaarden, L.; de Vries, A.; Elghobashi, S.; Huilier, D.; Peirano, E.; Minier, J.P.; Gavrilyuk, S.; Saurel, R.; Kashinsky, O.; Randin, V.; Colin, C.; Larue de Tournemine, A.; Roig, V.; Suzanne, C.; Bounhoure, C.; Brunet, Y.; Tanaka, A.T.; Noma, K.; Tsuji, Y.; Pascal-Ribot, S.; Le Gall, F.; Aliseda, A.; Hainaux, F.; Lasheras, J.; Didwania, A.; Costa, A.; Vallerin, W.; Mudde, R.F.; Van Den Akker, H.E.A.; Jaumouillie, P.; Larrarte, F.; Burgisser, A.; Bergantz, G.; Necker, F.; Hartel, C.; Kleiser, L.; Meiburg, E.; Michallet, H.; Mory, M.; Hutter, M.; Markov, A.A.; Dumoulin, F.X.; Suard, S.; Borghi, R.; Hong, M.; Hopfinger, E.; Laforgia, A.; Lawrence, C.J.; Hewitt, G.F.; Osiptsov, A.N.; Tsirkunov, Yu. M.; Volkov, A.N.

2003-07-01

This document gathers the abstracts of the Euromech 421 colloquium about strongly coupled dispersed two-phase flows. Behaviors specifically due to the two-phase character of the flow have been categorized as: suspensions, particle-induced agitation, microstructure and screening mechanisms; hydrodynamic interactions, dispersion and phase distribution; turbulence modulation by particles, droplets or bubbles in dense systems; collective effects in dispersed two-phase flows, clustering and phase distribution; large-scale instabilities and gravity driven dispersed flows; strongly coupled two-phase flows involving reacting flows or phase change. Topic l: suspensions particle-induced agitation microstructure and screening mechanisms hydrodynamic interactions between two very close spheres; normal stresses in sheared suspensions; a critical look at the rheological experiments of R.A. Bagnold; non-equilibrium particle configuration in sedimentation; unsteady screening of the long-range hydrodynamic interactions of settling particles; computer simulations of hydrodynamic interactions among a large collection of sedimenting poly-disperse particles; velocity fluctuations in a dilute suspension of rigid spheres sedimenting between vertical plates: the role of boundaries; screening and induced-agitation in dilute uniform bubbly flows at small and moderate particle Reynolds numbers: some experimental results. Topic 2: hydrodynamic interactions, dispersion and phase distribution: hydrodynamic interactions in a bubble array; A 'NMR scattering technique' for the determination of the structure in a dispersion of non-brownian settling particles; segregation and clustering during thermo-capillary migration of bubbles; kinetic modelling of bubbly flows; velocity fluctuations in a homogeneous dilute dispersion of high-Reynolds-number rising bubbles; an attempt to simulate screening effects at moderate particle Reynolds numbers using an hybrid formulation; modelling the two

Properties of alginate fiber spun-dyed with fluorescent pigment dispersion.

Science.gov (United States)

Wang, Ping; Tawiah, Benjamin; Tian, Anli; Wang, Chunxia; Zhang, Liping; Fu, Shaohai

2015-03-15

Spun-dyed alginate fiber was prepared by the spun-dyeing method with the mixture of fluorescent pigment dispersion and sodium alginate fiber spinning solution, and its properties were characterized by SEM, TGA, DSC, and XRD. The results indicate that fluorescent pigment dispersion prepared with esterified poly (styrene-alt maleic acid) had excellent compatibility with sodium alginate fiber spinning solution, and small amount of fluorescent pigment could reduce the viscosity of spun-dyed spinning solutions. SEM photo of spun-dyed alginate fiber indicated that fewer pigment particles deposited on its surface. TGA, DSC, and XRD results suggested that thermal properties and crystal phase of spun-dyed alginate fibers had slight changes compared to the original alginate fibers. The fluorescence intensity of spun-dyed alginate fiber reached its maximum when the content of fluorescent pigment was 4%. The spun-dyed alginate fiber showed excellent rubbing and washing fastness. Copyright © 2014 Elsevier Ltd. All rights reserved.

Synthesis and properties of aqueous polyurethane dispersions: Influence of molecular weight of polyethylene glycol

Energy Technology Data Exchange (ETDEWEB)

Mumtaz, Fatima; Zuber, Mohammad; Zia, Khalid Mahmood [Government College University, Faisalabad (Pakistan); Jamil, Tahir [University of the Punjab, Lahore (Pakistan); Hussain, Rizwan [National Engineering and Scientific Commission (NESCOM), Islamabad (Pakistan)

2013-12-15

Aqueous polyurethane dispersions (PUDs) have recently emerged as important alternatives to their solvent-based counterparts for various applications due to increasing health and environmental awareness. A series of aqueous polyurethane dispersions containing carboxylate anion as hydrophilic pendant groups were synthesized through step growth polymerization reaction using hexamethylene diisocyanate (HDI), 1,4-butanediol (1,4-BDO), dimethylol propionic acid (DMPA) and polyethylene glycol (PEG) of different molecular weight. Effect of PEG molecular weight was investigated on molecular structure, contact angle measurement, and physical and adhesive properties of PU emulsions. Fourier transform infrared spectroscopy (FT-IR) was used to check the completion of polymerization reaction. Contact angle measurement indicated that the hydrophilicity of polymer increases by increasing molecular weight of PEG with a corresponding decrease in contact angle. Results of T-peel test showed a decrease in peel strength by increasing molecular weight of PEG. Moreover, solid contents%, drying time and storage stability suggested fast drying properties and greater stability of aqueous PU dispersions.

Isolation of whiskers from natural sources and their dispersed in a non-aqueous medium

Directory of Open Access Journals (Sweden)

Mauro Vestena

Full Text Available Abstract Whiskers have been used as a nanomaterial dispersed in polymer matrices to modify the microscopic and macroscopic properties of the polymer. These nanomaterials can be isolated from cellulose, one of the most abundant natural renewable sources of biodegradable polymer. In this study, whiskers were isolated from sugarcane bagasse and corn cob straw fibers. Initially, the cellulose fiber was treated through an alkaline/oxidative process followed by acid hydrolysis. Dimethylformamide and dimethyl sulfoxide were used to replace the aqueous medium for the dispersion of the whiskers. For the solvent exchange, dimethylformamide or dimethyl sulfoxide was added to the aqueous dispersion and the water was then removed by fractional distillation. FTIR, TGA, XRD, TEM, Zeta and DLS techniques were used to evaluate the efficiency of the isolation process as well as the morphology and dimensions of the whiskers. The dimensions of the whiskers are comparable with values reported in the literature, maintaining the uniformity and homogeneity in both aqueous and non-aqueous solvents.

Isolation of whiskers from natural sources and their dispersed in a non-aqueous medium

Energy Technology Data Exchange (ETDEWEB)

Vestena, Mauro; Gross, Idejan Padilha; Pires, Alfredo Tiburcio Nunes; Muller, Carmen Maria Olivera, E-mail: mauro@utfpr.edu.br [Universidade Federal Santa Catarina (UFSC), Florianopolis, SC (Brazil)

2016-10-15

Whiskers have been used as a nano material dispersed in polymer matrices to modify the microscopic and macroscopic properties of the polymer. These nanomaterials can be isolated from cellulose, one of the most abundant natural renewable sources of biodegradable polymer. In this study, whiskers were isolated from sugarcane bagasse and corn cob straw fibers. Initially, the cellulose fiber was treated through an alkaline/oxidative process followed by acid hydrolysis. Dimethylformamide and dimethyl sulfoxide were used to replace the aqueous medium for the dispersion of the whiskers. For the solvent exchange, dimethylformamide or dimethyl sulfoxide was added to the aqueous dispersion and the water was then removed by fractional distillation. FTIR, TGA, XRD, TEM, Zeta and DLS techniques were used to evaluate the efficiency of the isolation process as well as the morphology and dimensions of the whiskers. The dimensions of the whiskers are comparable with values reported in the literature, maintaining the uniformity and homogeneity in both aqueous and non-aqueous solvents. (author)

Comparative Study on Dispersion and Interfacial Properties of Single Walled Carbon Nanotube/Polymer Composites Using Hansen Solubility Parameters

DEFF Research Database (Denmark)

Ma, Jing; Larsen, Mikael

2013-01-01

fabricated by solution blending 1 wt % SWNTs with various modification (nonmodified, nitric acid functionalized, and amine functionalized SWNTs) and three kinds of polymeric materials (polycarbonate, polyvinylidene fluoride, and epoxy). Chemical compatibilities between SWNTs and solvents or polymers...... are calculated by the Hansen solubility parameters (HSP) method. The dispersion of the SWNTs in solvents is evaluated by dynamic light scattering. The dispersion of SWNTs in polymers evaluated by a light optical microscope (LOM) generally agrees with the HSP prediction. The strain transfer from the matrix...

Monolithic lithium-based aerogels via dispersed inorganic sol-gel method

International Nuclear Information System (INIS)

Xiao Shufang; Zhou Bin; Du Ai; Xu Xiang; Yang Xiaoyun; Shen Jun; Wu Guangming; Zhang Zhihua; Wan Huijun

2008-01-01

Monolithic lithium-based aerogels were prepared by poly acrylic acid (PAA) and propylene oxide (PO) via the dispersed inorganic sol-gel method and drying with CO 2 supercritical fluid dry process. The density of the prepared sample is about 150 g/m 3 . The microstructure of the lithium-based aerogels was characterized by TEM, IR, XPS and BET. The results show that the material mainly contains Li, C and O element s. BET surface area is up to 18.9 m 2 /g. (authors)

Magnetic nanoparticles based dispersive micro-solid-phase extraction as a novel technique for coextraction of acidic and basic drugs from biological fluids and waste water.

Science.gov (United States)

Asgharinezhad, Ali Akbar; Mollazadeh, Narges; Ebrahimzadeh, Homeira; Mirbabaei, Fatemeh; Shekari, Nafiseh

2014-04-18

The coextraction of acidic and basic drugs from different samples is a considerable and disputable concept in sample preparation strategies. In this study, for the first time, simultaneous extraction of acidic and basic drugs with magnetic nanoparticles based dispersive micro-solid phase extraction followed by high performance liquid chromatography-ultraviolet detection was introduced. Cetyltrimethyl ammonium bromide-coated Fe3O4@decanoic acid as an efficient sorbent was successfully applied to adsorb diclofenac (DIC) as an acidic and diphenhydramine (DPH) as a basic model compound. First, appropriate amount of synthetic Fe3O4@decanoic acid nanoparticles was added to aqueous solution of drugs. After adjusting the pH of the solution, cetyltrimethyl ammonium bromide (CTAB) was added to the mixture being stirred at a constant rate. After the adsorption of drugs and decantation of supernatant with a magnetic field, the sorbent was eluted with methanol by fierce vortex. The parameters affecting the extraction efficiency were optimized and obtained as: pH of the sample=9, concentration of CTAB=0.2mmolL(-1), amount of sorbent=10mg, extraction time=5min, no salt addition to sample, type and volume of the eluent=50μL methanol, and desorption time=1min. Under the optimum conditions detection limits and linear dynamic ranges were achieved in the range of 1.8-3.0, 5-1500μgL(-1) for DPH and 1.5-3.5, 5-1500μgL(-1) for DIC, respectively. The percent of extraction recovery and relative standard deviations (n=5) were in the range of 47.3-60, 5.2-9.0 for DPH and 64-76.7, 5.1-5.8 for DIC, respectively. Ultimately, the applicability of the method was successfully confirmed by the extraction and determination of DIC and DPH in human urine, plasma and waste water samples in the range of microgram per liter and satisfactory results were obtained. Copyright © 2014 Elsevier B.V. All rights reserved.

A green deep eutectic solvent dispersive liquid-liquid micro-extraction (DES-DLLME) for the UHPLC-PDA determination of oxyprenylated phenylpropanoids in olive, soy, peanuts, corn, and sunflower oil.

Science.gov (United States)

Ferrone, Vincenzo; Genovese, Salvatore; Carlucci, Maura; Tiecco, Matteo; Germani, Raimondo; Preziuso, Francesca; Epifano, Francesco; Carlucci, Giuseppe; Taddeo, Vito Alessandro

2018-04-15

A green dispersive liquid-liquid microextraction (DLLME) using deep eutectic solvent (DES) as the extracting solvent has been developed and applied for the simultaneous quantification of ferulic acid, umbelliferone, boropinic acid, 7-isopentenyloxycoumarin, 4'-geranyloxyferulic acid (GOFA), and auraptene in some vegetable oils using ultra high performance liquid chromatography (UHPLC) with photodiode array detection (PDA). All parameters in the extraction step, including selection and loading of both extracting and dispersing solvents, amount of both extractant and disperser solvent were investigated and optimized. PhAA/TMG DES achieved higher recovery and enrichment factor compared to other DESs. The validated method showed good linearity with correlation coefficients, r 2 >0.9990 for all the analytes. Furthermore, this is the first time that eco-friendly solvents are used for the extraction of oxyprenylated phenylpropanoids and the corresponding extract analyzed with ultra high performance liquid chromatography with photodiode array detection. Copyright © 2017 Elsevier Ltd. All rights reserved.

Spectral phase shift and residual angular dispersion of an accousto-optic programme dispersive filter

International Nuclear Information System (INIS)

Boerzsoenyi, A.; Meroe, M.

2010-01-01

Complete text of publication follows. There is an increasing demand for active and precise dispersion control of ultrashort laser pulses. In chirped pulse amplification (CPA) laser systems, the dispersion of the optical elements of the laser has to be compensated at least to the fourth order to obtain high temporal contrast compressed pulses. Nowadays the most convenient device for active and programmable control of spectral phase and amplitude of broadband laser pulses is the acousto-optic programmable dispersive filter (AOPDF), claimed to be able to adjust the spectral phase up to the fourth order. Although it has been widely used, surprisingly enough there has been only a single, low resolution measurement reported on the accuracy of the induced spectral phase shift of the device. In our paper we report on the first systematic experiment aiming at the precise characterization of an AOPDF device. In the experiment the spectral phase shift of the AOPDF device was measured by spectrally and spatially resolved interferometry, which is especially powerful tool to determine small dispersion values with high accuracy. Besides the spectral phase dispersion, we measured both the propagation direction angular dispersion (PDAD) and the phase front angular dispersion (PhFAD). Although the two quantities are equal for plane waves, there may be noticeable difference for Gaussian pulses. PDAD was determined simply by focusing the beam on the slit of an imaging spectrograph, while PhFAD was measured by the use of an inverted Mach-Zehnder interferometer and an imaging spectrograph. In the measurements, the spectral phase shift and both types of angular dispersion have been recorded upon the systematic change of all the accessible functions of the acousto-optic programmable dispersive filter. The measured values of group delay dispersion (GDD) and third order dispersion (TOD) have been found to agree with the preset values within the error of the measurement (1 fs 2 and 10 fs 3

Characterization of acid tars

Energy Technology Data Exchange (ETDEWEB)

Leonard, Sunday A., E-mail: sunday.leonard@ucl.ac.uk [Department of Civil Environmental and Geomatic Engineering, University College London, Chadwick Building, Gower Street, London, WC1E 6BT (United Kingdom); Stegemann, Julia A. [Department of Civil Environmental and Geomatic Engineering, University College London, Chadwick Building, Gower Street, London, WC1E 6BT (United Kingdom); Roy, Amitava [J. Bennett Johnston, Sr., Centre for Advance Microstructures and Devices (CAMD), 6980 Jefferson Highway, Louisiana State University, Baton Rouge, LA, 70806 (United States)

2010-03-15

Acid tars from the processing of petroleum and petrochemicals using sulfuric acid were characterized by gas chromatography/mass spectrometry (GC/MS), inductively coupled plasma/optical emission spectrometry (ICP/OES), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectrometry, and scanning electron microscopy/energy dispersive X-ray (SEM/EDX) micro-analysis. Leaching of contaminants from the acid tars in 48 h batch tests with distilled water at a liquid-to-solid ratio 10:1 was also studied. GC/MS results show that the samples contained aliphatic hydrocarbons, cyclic hydrocarbons, up to 12 of the 16 USEPA priority polycyclic aromatic hydrocarbons (PAHs), and numerous other organic groups, including organic acids (sulfonic acids, carboxylic acids and aromatic acids), phenyl, nitrile, amide, furans, thiophenes, pyrroles, and phthalates, many of which are toxic. Metals analysis shows that Pb was present in significant concentration. DSC results show different transition peaks in the studied samples, demonstrating their complexity and variability. FTIR analysis further confirmed the presence of the organic groups detected by GC/MS. The SEM/EDX micro-analysis results provided insight on the surface characteristics of the samples and show that contaminants distribution was heterogeneous. The results provide useful data on the composition, complexity, and variability of acid tars; information which hitherto have been scarce in public domain.

Characterization of acid tars

International Nuclear Information System (INIS)

Leonard, Sunday A.; Stegemann, Julia A.; Roy, Amitava

2010-01-01

Acid tars from the processing of petroleum and petrochemicals using sulfuric acid were characterized by gas chromatography/mass spectrometry (GC/MS), inductively coupled plasma/optical emission spectrometry (ICP/OES), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectrometry, and scanning electron microscopy/energy dispersive X-ray (SEM/EDX) micro-analysis. Leaching of contaminants from the acid tars in 48 h batch tests with distilled water at a liquid-to-solid ratio 10:1 was also studied. GC/MS results show that the samples contained aliphatic hydrocarbons, cyclic hydrocarbons, up to 12 of the 16 USEPA priority polycyclic aromatic hydrocarbons (PAHs), and numerous other organic groups, including organic acids (sulfonic acids, carboxylic acids and aromatic acids), phenyl, nitrile, amide, furans, thiophenes, pyrroles, and phthalates, many of which are toxic. Metals analysis shows that Pb was present in significant concentration. DSC results show different transition peaks in the studied samples, demonstrating their complexity and variability. FTIR analysis further confirmed the presence of the organic groups detected by GC/MS. The SEM/EDX micro-analysis results provided insight on the surface characteristics of the samples and show that contaminants distribution was heterogeneous. The results provide useful data on the composition, complexity, and variability of acid tars; information which hitherto have been scarce in public domain.

Dispersal and assimilation of an aquaculture waste subsidy in a low productivity coastal environment.

Science.gov (United States)

White, C A; Nichols, P D; Ross, D J; Dempster, T

2017-07-15

To understand dispersal and assimilation of aquaculture waste subsidies in a naturally low-productivity environment, we applied a novel, rapid transmethylation technique to analyse sediment and biota fatty acid composition. This technique was initially validated at Atlantic salmon farms in Macquarie Harbour, Australia, where sediments were collected at farm and control locations. Subsequently, sediment, benthic polychaete and zooplankton were sampled at sites 0, 50, 250, 500 and 1000m distant from multiple cages. Results demonstrated an acute deposition zone up to 50m from cages and a diffuse zone extending 500m from cages. Changes in sediment concentration of linoleic acid, oleic acid and total fatty acids were effective tracers of farm deposition. Bacterial biomarkers indicated that aquaculture waste stimulates bacterial productivity in sediments, with elevated biomarker concentrations also detected in benthic polychaetes. Overall, fatty acid analysis was a sensitive technique to characterize the benthic footprint of aquaculture influence. Copyright © 2017 Elsevier Ltd. All rights reserved.

Observing trends in the functionalization of cnts using same oxidizing acids under two different conditions

International Nuclear Information System (INIS)

Aftab, S.

2013-01-01

Excellent electrical, mechanical, optical and thermal properties are attributed to carbon nanotubes. Carbon nanotubes need to be functionalized to form a homogeneous dispersion. In this work, catalytically produced carbon nanotubes have been functionalized under two different conditions using the same acid medium. The effect of the two reaction routes on the carbon nanotubes, in terms of the extent of covalent functionalization has been determined by several techniques. Scanning electron microscopy aided in the observation of their morphology and X-ray diffraction was used to ascertain their structure. Other analytical characterization tools employed were Fourier transform infrared spectroscopy, Zeta potential measurement, UV spectroscopy, Oxygen percentage analysis, Boehm's titration and visual dispersion. Results show that carbon nanotubes functionalized by refluxing in the acids are much better dispersed. (author)

Well-dispersed cellulose nanocrystals in hydrophobic polymers by in situ polymerization for synthesizing highly reinforced bio-nanocomposites.

Science.gov (United States)

Geng, Shiyu; Wei, Jiayuan; Aitomäki, Yvonne; Noël, Maxime; Oksman, Kristiina

2018-04-20

In nanocomposites, dispersing hydrophilic nanomaterials in a hydrophobic matrix using simple and environmentally friendly methods remains challenging. Herein, we report a method based on in situ polymerization to synthesize nanocomposites of well-dispersed cellulose nanocrystals (CNCs) and poly(vinyl acetate) (PVAc). We have also shown that by blending this PVAc/CNC nanocomposite with poly(lactic acid) (PLA), a good dispersion of the CNCs can be reached in PLA. The outstanding dispersion of CNCs in both PVAc and PLA/PVAc matrices was shown by different microscopy techniques and was further supported by the mechanical and rheological properties of the composites. The in situ PVAc/CNC nanocomposites exhibit enhanced mechanical properties compared to the materials produced by mechanical mixing, and a theoretical model based on the interphase effect and dispersion that reflects this behavior was developed. Comparison of the rheological and thermal behaviors of the mixed and in situ PVAc/CNC also confirmed the great improvement in the dispersion of nanocellulose in the latter. Furthermore, a synergistic effect was observed with only 0.1 wt% CNCs when the in situ PVAc/CNC was blended with PLA, as demonstrated by significant increases in elastic modulus, yield strength, elongation to break and glass transition temperature compared to the PLA/PVAc only material.

Design and development of a dust dispersion chamber to quantify the dispersibility of rock dust.

Science.gov (United States)

Perera, Inoka E; Sapko, Michael J; Harris, Marcia L; Zlochower, Isaac A; Weiss, Eric S

2016-01-01

Dispersible rock dust must be applied to the surfaces of entries in underground coal mines in order to inert the coal dust entrained or made airborne during an explosion and prevent propagating explosions. 30 CFR. 75.2 states that "… [rock dust particles] when wetted and dried will not cohere to form a cake which will not be dispersed into separate particles by a light blast of air …" However, a proper definition or quantification of "light blast of air" is not provided. The National Institute for Occupational Safety and Health (NIOSH) has, consequently, designed a dust dispersion chamber to conduct quantitative laboratory-scale dispersibility experiments as a screening tool for candidate rock dusts. A reproducible pulse of air is injected into the chamber and across a shallow tray of rock dust. The dust dispersed and carried downwind is monitored. The mass loss of the dust tray and the airborne dust measurements determine the relative dispersibility of the dust with respect to a Reference rock dust. This report describes the design and the methodology to evaluate the relative dispersibility of rock dusts with and without anti-caking agents. Further, the results of this study indicate that the dispersibility of rock dusts varies with particle size, type of anti-caking agent used, and with the untapped bulk density. Untreated rock dusts, when wetted and dried forming a cake that was much less dispersible than the reference rock dust used in supporting the 80% total incombustible content rule.

Simultaneous Determination of Food-Related Biogenic Amines and Precursor Amino Acids Using in Situ Derivatization Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction by Ultra-High-Performance Liquid Chromatography Tandem Mass Spectrometry.

Science.gov (United States)

He, Yongrui; Zhao, Xian-En; Wang, Renjun; Wei, Na; Sun, Jing; Dang, Jun; Chen, Guang; Liu, Zhiqiang; Zhu, Shuyun; You, Jinmao

2016-11-02

A simple, rapid, sensitive, selective, and environmentally friendly method, based on in situ derivatization ultrasound-assisted dispersive liquid-liquid microextraction (in situ DUADLLME) coupled with ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) using multiple reaction monitoring (MRM) mode has been developed for the simultaneous determination of food-related biogenic amines and amino acids. A new mass-spectrometry-sensitive derivatization reagent 4'-carbonyl chloride rosamine (CCR) was designed, synthesized, and first reported. Parameters and conditions of in situ DUADLLME and UHPLC-MS/MS were optimized in detail. Under the optimized conditions, the in situ DUADLLME was completed speedily (within 1 min) with high derivatization efficiencies (≥98.5%). With the cleanup and concentration of microextraction step, good analytical performance was obtained for the analytes. The results showed that this method was accurate and practical for quantification of biogenic amines and amino acids in common food samples (red wine, beer, wine, cheese, sausage, and fish).

Electrophoretic deposition of composite halloysite nanotube–hydroxyapatite–hyaluronic acid films

Energy Technology Data Exchange (ETDEWEB)

Deen, I. [Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L7 (Canada); Zhitomirsky, I., E-mail: zhitom@mcmaster.ca [Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L7 (Canada)

2014-02-15

Highlights: ► Composite halloysite nanotubes–hydroxyapatite–hyaluronic acid films were prepared. ► Electrophoretic deposition method was used for deposition. ► Natural hyaluronic acid was used as a dispersing, charging and film forming agent. ► Film composition and deposition yield can be varied. ► The films can be used for biomedical implants with controlled release of drugs. -- Abstract: Electrophoretic deposition method has been developed for the deposition of biocomposite films containing halloysite nanotubes (HNTs), hydroxyapatite (HA) and hyaluronic acid. The method is based on the use of natural hyaluronate biopolymer as a dispersing and charging agent for HNT and HA and film forming agent for the fabrication of the composite films. The deposition kinetics was studied by the quartz crystal microbalance method. The composite films were studied by X-ray diffraction, thermogravimetric analysis, differential thermal analysis and electron microscopy. The composite films are promising materials for the fabrication of biomedical implants with advanced functional properties.

Electrophoretic deposition of composite halloysite nanotube–hydroxyapatite–hyaluronic acid films

International Nuclear Information System (INIS)

Deen, I.; Zhitomirsky, I.

2014-01-01

Highlights: ► Composite halloysite nanotubes–hydroxyapatite–hyaluronic acid films were prepared. ► Electrophoretic deposition method was used for deposition. ► Natural hyaluronic acid was used as a dispersing, charging and film forming agent. ► Film composition and deposition yield can be varied. ► The films can be used for biomedical implants with controlled release of drugs. -- Abstract: Electrophoretic deposition method has been developed for the deposition of biocomposite films containing halloysite nanotubes (HNTs), hydroxyapatite (HA) and hyaluronic acid. The method is based on the use of natural hyaluronate biopolymer as a dispersing and charging agent for HNT and HA and film forming agent for the fabrication of the composite films. The deposition kinetics was studied by the quartz crystal microbalance method. The composite films were studied by X-ray diffraction, thermogravimetric analysis, differential thermal analysis and electron microscopy. The composite films are promising materials for the fabrication of biomedical implants with advanced functional properties

Surface acidity scales: Experimental measurements of Brønsted acidities on anatase TiO2 and comparison with coinage metal surfaces

Science.gov (United States)

Silbaugh, Trent L.; Boaventura, Jaime S.; Barteau, Mark A.

2016-08-01

The first quantitative surface acidity scale for Brønsted acids on a solid surface is presented through the use of titration-displacement and equilibrium experiments on anatase TiO2. Surface acidities of species on TiO2 correlated with gas phase acidities, as was previously observed in qualitative studies of Brønsted acid displacement on Ag(110), Cu(110) and Au(111). A 90% compression of the surface acidity scale relative to the gas phase was observed due to compensation from the covalent component of the conjugate base - surface bond. Adsorbed conjugate bases need not be completely anionic for correlations with gas phase acidities to hold. Positive and negative substituent effects, such as substituted fluorine and hydrocarbon sidechain dispersion interactions with the surface, may modify the surface acidity scale, in agreement with previous experimental and theoretical work on Au(111).

Dispersal kernel estimation: A comparison of empirical and modelled particle dispersion in a coastal marine system

Science.gov (United States)

Hrycik, Janelle M.; Chassé, Joël; Ruddick, Barry R.; Taggart, Christopher T.

2013-11-01

Early life-stage dispersal influences recruitment and is of significance in explaining the distribution and connectivity of marine species. Motivations for quantifying dispersal range from biodiversity conservation to the design of marine reserves and the mitigation of species invasions. Here we compare estimates of real particle dispersion in a coastal marine environment with similar estimates provided by hydrodynamic modelling. We do so by using a system of magnetically attractive particles (MAPs) and a magnetic-collector array that provides measures of Lagrangian dispersion based on the time-integration of MAPs dispersing through the array. MAPs released as a point source in a coastal marine location dispersed through the collector array over a 5-7 d period. A virtual release and observed (real-time) environmental conditions were used in a high-resolution three-dimensional hydrodynamic model to estimate the dispersal of virtual particles (VPs). The number of MAPs captured throughout the collector array and the number of VPs that passed through each corresponding model location were enumerated and compared. Although VP dispersal reflected several aspects of the observed MAP dispersal, the comparisons demonstrated model sensitivity to the small-scale (random-walk) particle diffusivity parameter (Kp). The one-dimensional dispersal kernel for the MAPs had an e-folding scale estimate in the range of 5.19-11.44 km, while those from the model simulations were comparable at 1.89-6.52 km, and also demonstrated sensitivity to Kp. Variations among comparisons are related to the value of Kp used in modelling and are postulated to be related to MAP losses from the water column and (or) shear dispersion acting on the MAPs; a process that is constrained in the model. Our demonstration indicates a promising new way of 1) quantitatively and empirically estimating the dispersal kernel in aquatic systems, and 2) quantitatively assessing and (or) improving regional hydrodynamic

Comparative Study of Stearic Acid/Iron-Oxide Binary and Stearic Acid/Iron-Oxide/Titanium-Oxide Ternary for Use as Energy Storage Material

International Nuclear Information System (INIS)

Andiarto, Rizky; Nuryadin, Muhammad Khalish; Saleh, Rosari

2016-01-01

In this work, a series of stearic acid/Fe 3 O 4 , and stearic acid/Fe 3 O 4 /TiO 2 nanocomposites for thermal energy storage (TES) system were synthesized through a two-step process. Fe 3 O 4 nanoparticles and Fe 3 O 4 /TiO 2 nanocomposites were first prepared using sol-gel methods and then both samples were mixed into stearic acid by dispersion technique at three different weight % ratio to stearic acid: 5%, 10% and 15% to obtain stearic acid/Fe 3 O 4 , and stearic acid/Fe 3 O 4 /TiO 2 nanocomposites. Morphologies and structural properties of the samples were characterized by X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FESEM) and energy dispersive X-ray spectroscopy (EDX), while thermal properties of the sample were determined by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The XRD patterns demonstrate, that stearic acid/Fe 3 O 4 contained characteristic peaks of Fe 3 O 4 and stearic acid structures, while peaks corresponded to anatase TiO 2 structures appear in stearic acid/ Fe 3 O 4 /TiO 2 nanocomposites. From the DSC measurements, it is found that the maximum latent heat was found at samples with weight ratio of 5%. Moreover, the enhancement up to 20% of latent heat in solidifying as well as melting processes was observed. TGA measurements show high degradation temperature in the range of 246 - 251°C. The TGA results also shows that the residual mass of the sample matches the composition of Fe 3 O 4 and Fe 3 O 4 /TiO 2 which is added to the stearic acid. (paper)

Laser control of natural disperse systems

Science.gov (United States)

Vlasova, Olga L.; Bezrukova, Alexandra G.

2003-10-01

Different water disperse systems were studied by integral (spectroturbidemetry) and differential light scattering method with a laser as a source of light. The investigation done concerns the state of kaolin dispersions at storage and under dilution as an example of mineral dispersion systems such as natural water. The role of some light scattering parameters for an optical analysis of water dispersions, like the dispersion of erythrocytes and bacterial cells -Escherichia coli is discussed. The results obtained can help to elaborate the methods for on-line optical control fo natural disperse systems (water, air) with mineral and biological particles.

Dispersant trial at ANO-2: Results from a short-term trial prior to SG replacement

International Nuclear Information System (INIS)

Fruzzetti, K.; Frattini, P.; Robbins, P.; Miller, A.; Varrin, R.; Kreider, M.

2002-01-01

Corrosion products in the secondary side of pressurized water reactor (PWR) steam generators (SGs) primarily deposit on the SG tubes. These deposits can inhibit heat transfer, lead to thermal-hydraulic instabilities through blockage of tube supports, and create occluded regions where corrosive species can concentrate along tubes and in tube-to-tube support plate crevices. The performance of the SGs is compromised not only by formation of an insulating scale, but by the removal of tubes from service due to corrosion. A potential strategy for minimizing deposition of corrosion products on SG internal surfaces is to use an online dispersant to help prevent the corrosion products from adhering to the steam generator surfaces. By inhibiting the deposition of the corrosion products, the dispersant can facilitate more effective removal from the SGs via blowdown. This type of strategy has been employed at fossil boilers for many decades. However, due to the use of inorganic (sulfur and other impurities) polymerization initiators, polymeric dispersants had not been utilized in the nuclear industry. Only recently has a poly-acrylic acid dispersant, developed by BetzDearborn (PAA), been available that meets the criteria for nuclear application. This paper summarizes the results of the short-term PAA dispersant trial in Winter/Spring 2000, lasting approximately 3 months, performed at Arkansas nuclear one unit 2 (ANO-2)-including the chronology of the trial, the increase in blowdown iron removal efficiency with use of the dispersant, and observed effects on SG performance. (authors)

Dispersant trial at ANO-2: Results from a short-term trial prior to SG replacement

Energy Technology Data Exchange (ETDEWEB)

Fruzzetti, K.; Frattini, P. [Electric Power Research Inst., Palo Alto, CA (United States); Robbins, P. [Entergy Operations, Arkansas Nuclear One, Russellville, AR (United States); Miller, A. [Pedro Point Technology, Inc., Pacifica, CA (United States); Varrin, R.; Kreider, M. [Dominion Engineering Inc., McLean, VA (United States)

2002-07-01

Corrosion products in the secondary side of pressurized water reactor (PWR) steam generators (SGs) primarily deposit on the SG tubes. These deposits can inhibit heat transfer, lead to thermal-hydraulic instabilities through blockage of tube supports, and create occluded regions where corrosive species can concentrate along tubes and in tube-to-tube support plate crevices. The performance of the SGs is compromised not only by formation of an insulating scale, but by the removal of tubes from service due to corrosion. A potential strategy for minimizing deposition of corrosion products on SG internal surfaces is to use an online dispersant to help prevent the corrosion products from adhering to the steam generator surfaces. By inhibiting the deposition of the corrosion products, the dispersant can facilitate more effective removal from the SGs via blowdown. This type of strategy has been employed at fossil boilers for many decades. However, due to the use of inorganic (sulfur and other impurities) polymerization initiators, polymeric dispersants had not been utilized in the nuclear industry. Only recently has a poly-acrylic acid dispersant, developed by BetzDearborn (PAA), been available that meets the criteria for nuclear application. This paper summarizes the results of the short-term PAA dispersant trial in Winter/Spring 2000, lasting approximately 3 months, performed at Arkansas nuclear one unit 2 (ANO-2)-including the chronology of the trial, the increase in blowdown iron removal efficiency with use of the dispersant, and observed effects on SG performance. (authors)

New Yellow Synergist for Stable Pigment Dispersion of Inkjet Ink.

Science.gov (United States)

Song, Gihyun; Lee, Hayoon; Jung, Hyocheol; Kang, Seokwoo; Park, Jongwook

2018-02-01

Minimizing ink droplet and self-dispersed pigment mixture are becoming hot issues for high resolution of inkjet printing. New synergist including sulfonic acid group of PY-74 was suggested and synthesized. Pigment itself did not show water solubility but new synergist, SY-11 exhibited good solubility in water and organic solvents such as DMSO and DMF. When aqueous pigment ink was prepared with SY-11, storage stability of the ink has been remained for 7 days under periodically repeated heating and cooling conditions. Particle size of formulated ink was around 150 nm.

Comparison of two novel in-syringe dispersive liquid-liquid microextraction techniques for the determination of iodide in water samples using spectrophotometry.

Science.gov (United States)

Kaykhaii, Massoud; Sargazi, Mona

2014-01-01

Two new, rapid methodologies have been developed and applied successfully for the determination of trace levels of iodide in real water samples. Both techniques are based on a combination of in-syringe dispersive liquid-liquid microextraction (IS-DLLME) and micro-volume UV-Vis spectrophotometry. In the first technique, iodide is oxidized with nitrous acid to the colorless anion of ICl2(-) at high concentration of hydrochloric acid. Rhodamine B is added and by means of one step IS-DLLME, the ion-pair formed was extracted into toluene and measured spectrophotometrically. Acetone is used as dispersive solvent. The second method is based on the IS-DLLME microextraction of iodide as iodide/1, 10-phenanthroline-iron((II)) chelate cation ion-pair (colored) into nitrobenzene. Methanol was selected as dispersive solvent. Optimal conditions for iodide extraction were determined for both approaches. Methods are compared in terms of analytical parameters such as precision, accuracy, speed and limit of detection. Both methods were successfully applied to determining iodide in tap and river water samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Fickian dispersion is anomalous

Science.gov (United States)

Cushman, John H.; O'Malley, Dan

2015-12-01

The thesis put forward here is that the occurrence of Fickian dispersion in geophysical settings is a rare event and consequently should be labeled as anomalous. What people classically call anomalous is really the norm. In a Lagrangian setting, a process with mean square displacement which is proportional to time is generally labeled as Fickian dispersion. With a number of counter examples we show why this definition is fraught with difficulty. In a related discussion, we show an infinite second moment does not necessarily imply the process is super dispersive. By employing a rigorous mathematical definition of Fickian dispersion we illustrate why it is so hard to find a Fickian process. We go on to employ a number of renormalization group approaches to classify non-Fickian dispersive behavior. Scaling laws for the probability density function for a dispersive process, the distribution for the first passage times, the mean first passage time, and the finite-size Lyapunov exponent are presented for fixed points of both deterministic and stochastic renormalization group operators. The fixed points of the renormalization group operators are p-self-similar processes. A generalized renormalization group operator is introduced whose fixed points form a set of generalized self-similar processes. Power-law clocks are introduced to examine multi-scaling behavior. Several examples of these ideas are presented and discussed.

Does an ant-dispersed plant, Viola reichenbachiana, suffer from reduced seed dispersal under inundation disturbances?

NARCIS (Netherlands)

Prinzing, A.; Dauber, J.; Hammer, E.; Hammouti, N.; Bohning-Gaese, K.

2008-01-01

Many plant species use ants as seed dispersers. This dispersal mode is considered to be susceptible to disturbances, but the effect of natural, small-scale disturbances is still unknown. We investigated how small-scale disturbances due to inundation affect seed dispersal in Viola reichenbachiana, a

Clock synchronization and dispersion

International Nuclear Information System (INIS)

Giovannetti, Vittorio; Lloyd, Seth; Maccone, Lorenzo; Wong, Franco N C

2002-01-01

We present a method to defeat effects of dispersion of timing signals when synchronizing clocks. It is based on the recently proposed 'conveyor belt synchronization' scheme and on the quantum dispersion cancellation effect

Nozzle for electric dispersion reactor

Science.gov (United States)

Sisson, W.G.; Basaran, O.A.; Harris, M.T.

1995-11-07

A nozzle for an electric dispersion reactor includes two concentric electrodes, the inner one of the two delivering disperse phase fluid into a continuous phase fluid. A potential difference generated by a voltage source creates a dispersing electric field at the end of the inner electrode. 4 figs.

Simultaneous determination and qualitative analysis of six types of components in Naoxintong capsule by miniaturized matrix solid-phase dispersion extraction coupled with ultra high-performance liquid chromatography with photodiode array detection and quadrupole time-of-flight mass spectrometry.

Science.gov (United States)

Wang, Huilin; Jiang, Yan; Ding, Mingya; Li, Jin; Hao, Jia; He, Jun; Wang, Hui; Gao, Xiu-Mei; Chang, Yan-Xu

2018-02-03

A simple and effective sample preparation process based on miniaturized matrix solid-phase dispersion was developed for simultaneous determination of phenolic acids (gallic acid, chlorogenic acid, ferulic acid, 3,5-dicaffeoylqunic acid, 1,5-dicaffeoylqunic acid, rosmarinic acid, lithospermic acid, and salvianolic acid B), flavonoids (kaempferol-3-O-rutinoside, calycosin, and formononetin), lactones (ligustilide and butyllidephthalide), monoterpenoids (paeoniflorin), phenanthraquinones (cryptotanshinone), and furans (5-hydroxymethylfurfural) in Naoxintong capsule by ultra high-performance liquid chromatography. The optimized condition was that 25 mg Naoxintong powder was blended homogeneously with 100 mg Florisil PR for 4 min. One milliliter of methanol/water (75:25, v/v) acidified by 0.05% formic acid was selected to elute all components. It was found that the recoveries of the six types of components ranged from 61.36 to 96.94%. The proposed miniaturized matrix solid-phase dispersion coupled with ultra high-performance liquid chromatography was successfully applied to simultaneous determination of the six types of components in Naoxintong capsules. The results demonstrated that the proposed miniaturized matrix solid-phase dispersion coupled with ultra high-performance liquid chromatography could be used as an environmentally friendly tool for the extraction and determination of multiple bioactive components in natural products. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Spin-coating: A new approach for improving dispersion of cellulose nanocrystals and mechanical properties of poly (lactic acid) composites.

Science.gov (United States)

Shojaeiarani, Jamileh; Bajwa, Dilpreet S; Stark, Nicole M

2018-06-15

This study systematically evaluated the influence of masterbatch preparation techniques, solvent casting and spin-coating methods, on composite properties. Composites were manufactured by combining CNCs masterbatches and PLA resin using twin screw extruder followed by injection molding. Different microscopy techniques were used to investigate the dispersion of CNCs in masterbatches and composites. Thermal, thermomechanical, and mechanical properties of composites were evaluated. Scanning electron microscopy (SEM) images showed superior dispersion of CNCs in spin-coated masterbatches compared to solvent cast masterbatches. At lower CNCs concentrations, both SEM and optical microscope images confirmed more uniform CNCs dispersion in spin-coated composites than solvent cast samples. Degree of crystallinity of PLA exhibited a major enhancement by 147% and 380% in solvent cast and spin-coated composites, respectively. Spin-coated composites with lower CNCs concentration exhibited a noticeable improvement in mechanical properties. However, lower thermal characteristics in spin-coated composites were observed, which could be attributed to the residual solvents in masterbatches. Copyright © 2018 Elsevier Ltd. All rights reserved.

Synthesis of ZnO nanorods-Au nanoparticles hybrids via in-situ plasma sputtering-assisted method for simultaneous electrochemical sensing of ascorbic acid and uric acid

Energy Technology Data Exchange (ETDEWEB)

Hou, Chao [College of Life Information Science & Instrument Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Liu, Hongying, E-mail: liuhongying@hdu.edu.cn [College of Life Information Science & Instrument Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry & Chemical Engineering, Nanjing University, Nanjing 210093 (China); Zhang, Dan; Yang, Chi [Department of Pharmacy, Nantong University, Nantong 226001 (China); Zhang, Mingzhen [College of Life Information Science & Instrument Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China)

2016-05-05

In this study, ZnO nanorods-Au nanoparticles (ZnO NRs-Au NPs) hybrids were prepared using an in-situ plasma sputtering-assisted method without any template. Characterization results from scanning electron microscopy, high-resolution transmission electron microscopy, and energy dispersive X-ray spectroscopy showed that Au NPs are highly dispersed and tightly anchored on the surface of ZnO NRs. The size and surface coverage of Au NPs were well controlled by plasma sputtering time. Moreover, the hybrids exhibited excellent electrocatalytic properties towards oxidation of ascorbic acid (AA) and uric acid (UA) due to large surface area of Au NPs and ZnO NRs, and thus can be used as electrochemical sensors. Differential pulse voltammetry results showed that AA and UA could be detected simultaneously by ZnO NRs-Au NPs hybrids modified glassy carbon electrode. The linear ranges for AA and UA are 0.1 to 4 mM and 0.01 to 0.4 mM, respectively. The results suggest promising future applications in clinical diagnosis. - Highlights: • ZnO nanorods-Au nanoparticles were synthesized by in-situ plasma sputtering method. • Influence of sputtering time on the formation of Au nanoparticles was studied. • It exhibited a strong electrocatalytic activity toward the oxidation of ascorbic acid and uric acid. • A portable and cheap approach for simultaneous detection of ascorbic acid and uric acid was developed.

Synthesis of ZnO nanorods-Au nanoparticles hybrids via in-situ plasma sputtering-assisted method for simultaneous electrochemical sensing of ascorbic acid and uric acid

International Nuclear Information System (INIS)

Hou, Chao; Liu, Hongying; Zhang, Dan; Yang, Chi; Zhang, Mingzhen

2016-01-01

In this study, ZnO nanorods-Au nanoparticles (ZnO NRs-Au NPs) hybrids were prepared using an in-situ plasma sputtering-assisted method without any template. Characterization results from scanning electron microscopy, high-resolution transmission electron microscopy, and energy dispersive X-ray spectroscopy showed that Au NPs are highly dispersed and tightly anchored on the surface of ZnO NRs. The size and surface coverage of Au NPs were well controlled by plasma sputtering time. Moreover, the hybrids exhibited excellent electrocatalytic properties towards oxidation of ascorbic acid (AA) and uric acid (UA) due to large surface area of Au NPs and ZnO NRs, and thus can be used as electrochemical sensors. Differential pulse voltammetry results showed that AA and UA could be detected simultaneously by ZnO NRs-Au NPs hybrids modified glassy carbon electrode. The linear ranges for AA and UA are 0.1 to 4 mM and 0.01 to 0.4 mM, respectively. The results suggest promising future applications in clinical diagnosis. - Highlights: • ZnO nanorods-Au nanoparticles were synthesized by in-situ plasma sputtering method. • Influence of sputtering time on the formation of Au nanoparticles was studied. • It exhibited a strong electrocatalytic activity toward the oxidation of ascorbic acid and uric acid. • A portable and cheap approach for simultaneous detection of ascorbic acid and uric acid was developed.

Statistical Thermodynamics of Disperse Systems

DEFF Research Database (Denmark)

Shapiro, Alexander

1996-01-01

Principles of statistical physics are applied for the description of thermodynamic equilibrium in disperse systems. The cells of disperse systems are shown to possess a number of non-standard thermodynamic parameters. A random distribution of these parameters in the system is determined....... On the basis of this distribution, it is established that the disperse system has an additional degree of freedom called the macro-entropy. A large set of bounded ideal disperse systems allows exact evaluation of thermodynamic characteristics. The theory developed is applied to the description of equilibrium...

Geometry of physical dispersion relations

International Nuclear Information System (INIS)

Raetzel, Dennis; Rivera, Sergio; Schuller, Frederic P.

2011-01-01

To serve as a dispersion relation, a cotangent bundle function must satisfy three simple algebraic properties. These conditions are derived from the inescapable physical requirements that local matter field dynamics must be predictive and allow for an observer-independent notion of positive energy. Possible modifications of the standard relativistic dispersion relation are thereby severely restricted. For instance, the dispersion relations associated with popular deformations of Maxwell theory by Gambini-Pullin or Myers-Pospelov are not admissible. Dispersion relations passing the simple algebraic checks derived here correspond to physically admissible Finslerian refinements of Lorentzian geometry.

Direct electron transfer of Cytochrome c at mono-dispersed and negatively charged perylene-graphene matrix.

Science.gov (United States)

Zhang, Nan; Lv, Xiangyu; Ma, Weiguang; Hu, Yuwei; Li, Fenghua; Han, Dongxue; Niu, Li

2013-03-30

Mono-dispersed 3,4,9,10-perylene tetracarboxylic acid (PTCA) functionalized graphene sheets (PTCA-graphene) were fabricated by a chemical route and dispersed well in aqueous solution. PTCA-graphene with plenty of -COOH groups as electrostatic absorbing sites were beneficial to the loading of Cytochrome c (Cyt c). Cyt c, which was tightly immobilized on the PTCA-graphene modified glassy carbon electrode, maintained its natural conformation. Direct electron transfer of Cyt c and the electro-catalytic activity towards the reduction of H2O2 were also achieved. It has been substantiated that PTCA-graphene is a preferable biocompatible matrix for Cyt c. Copyright © 2012 Elsevier B.V. All rights reserved.

Determination of dispersity of crushed granite

International Nuclear Information System (INIS)

Liu Dejun; Fan Xianhua; Zhang Yingjie; Yao Jun; Zhou Duo; Wang Yong

2004-01-01

The experimental crushed granite column breakthrough curves, using 99 Tc as spike tracer and 3 H as invariant tracer, are analyzed by different linear regression techniques. Dispersity of crushed granite and retardation factor of 99 TcO 4 - on the crushed granite are determined simultaneously by one linear regression technique. Dispersity of crushed granite is also obtained with 3 H as invariant tracer by the other linear regression technique. The dispersities found by spike source and invariant source methods are compared. The experimental results show that the dispersity found by spike source method is close to that found by invariant source method. It indicates that dispersity is only the characteristic of dispersion medium

Determination of dispersity of crushed granite

International Nuclear Information System (INIS)

Liu, D.J.; Fan, X.H.

2005-01-01

Experimental crushed granite column breakthrough curves, using 99 Tc as spike tracer and 3 H as invariant tracer, were analyzed by different linear regression techniques. Dispersity of crushed granite and the retardation factor of 99 TcO 4 - on the crushed granite were determined simultaneously by one linear regression. Dispersity of crushed granite was also obtained with 3 H as invariant tracer by the other linear regression. The dispersities found by spike source and invariant source methods are compared. Experimental results show that the dispersity found by the spike source method is close to that found by the invariant source method. This indicates that dispersity is only a characteristic of the dispersion medium. (author)

Heterotrimeric Kinesin II Is the Microtubule Motor Protein Responsible for Pigment Dispersion in Xenopus Melanophores

Science.gov (United States)

Tuma, M. Carolina; Zill, Andrew; Le Bot, Nathalie; Vernos, Isabelle; Gelfand, Vladimir

1998-01-01

Melanophores move pigment organelles (melanosomes) from the cell center to the periphery and vice-versa. These bidirectional movements require cytoplasmic microtubules and microfilaments and depend on the function of microtubule motors and a myosin. Earlier we found that melanosomes purified from Xenopus melanophores contain the plus end microtubule motor kinesin II, indicating that it may be involved in dispersion (Rogers, S.L., I.S. Tint, P.C. Fanapour, and V.I. Gelfand. 1997. Proc. Natl. Acad. Sci. USA. 94: 3720–3725). Here, we generated a dominant-negative construct encoding green fluorescent protein fused to the stalk-tail region of Xenopus kinesin-like protein 3 (Xklp3), the 95-kD motor subunit of Xenopus kinesin II, and introduced it into melanophores. Overexpression of the fusion protein inhibited pigment dispersion but had no effect on aggregation. To control for the specificity of this effect, we studied the kinesin-dependent movement of lysosomes. Neither dispersion of lysosomes in acidic conditions nor their clustering under alkaline conditions was affected by the mutant Xklp3. Furthermore, microinjection of melanophores with SUK4, a function-blocking kinesin antibody, inhibited dispersion of lysosomes but had no effect on melanosome transport. We conclude that melanosome dispersion is powered by kinesin II and not by conventional kinesin. This paper demonstrates that kinesin II moves membrane-bound organelles. PMID:9852150

Dispersive shock waves in systems with nonlocal dispersion of Benjamin-Ono type

Science.gov (United States)

El, G. A.; Nguyen, L. T. K.; Smyth, N. F.

2018-04-01

We develop a general approach to the description of dispersive shock waves (DSWs) for a class of nonlinear wave equations with a nonlocal Benjamin-Ono type dispersion term involving the Hilbert transform. Integrability of the governing equation is not a pre-requisite for the application of this method which represents a modification of the DSW fitting method previously developed for dispersive-hydrodynamic systems of Korteweg-de Vries (KdV) type (i.e. reducible to the KdV equation in the weakly nonlinear, long wave, unidirectional approximation). The developed method is applied to the Calogero-Sutherland dispersive hydrodynamics for which the classification of all solution types arising from the Riemann step problem is constructed and the key physical parameters (DSW edge speeds, lead soliton amplitude, intermediate shelf level) of all but one solution type are obtained in terms of the initial step data. The analytical results are shown to be in excellent agreement with results of direct numerical simulations.

Waterfowl endozoochory: An overlooked long-distance dispersal mode for Cuscuta (dodder).

Science.gov (United States)

Costea, Mihai; Stefanović, Saša; García, Miguel A; De La Cruz, Susan; Casazza, Michael L; Green, Andy J

2016-05-01

Dispersal of parasitic Cuscuta species (dodders) worldwide has been assumed to be largely anthropomorphic because their seeds do not match any previously known dispersal syndrome and no natural dispersal vectors have been reliably documented. However, the genus has a subcosmopolitan distribution and recent phylogeographic results have indicated that at least18 historical cases of long-distance dispersal (LDD) have occurred during its evolution. The objective of this study is to report the first LDD biological vector for Cuscuta seeds. Twelve northern pintails (Anas acuta) were collected from Suisun Marsh, California and the contents of their lowest part of the large intestine (rectum) were extracted and analyzed. Seed identification was done both morphologically and using a molecular approach. Extracted seeds were tested for germination and compared to seeds not subjected to gut passage to determine the extent of structural changes caused to the seed coat by passing through the digestive tract. Four hundred and twenty dodder seeds were found in the rectum of four northern pintails. From these, 411 seeds were identified as Cuscuta campestris and nine as most likely C. pacifica. The germination rate of C. campestris seeds after gut passage was 55%. Structural changes caused by the gut passage in both species were similar to those caused by an acid scarification. Endozoochory by waterbirds may explain the historical LDD cases in the evolution of Cuscuta. This also suggests that current border quarantine measures may be insufficient to stopping spreading of dodder pests along migratory flyways. © 2016 Botanical Society of America.

Demonstration of Lignin-to-Peroxidase Direct Electron Transfer

Science.gov (United States)

Sáez-Jiménez, Verónica; Baratto, Maria Camilla; Pogni, Rebecca; Rencoret, Jorge; Gutiérrez, Ana; Santos, José Ignacio; Martínez, Angel T.; Ruiz-Dueñas, Francisco Javier

2015-01-01

Versatile peroxidase (VP) is a high redox-potential peroxidase of biotechnological interest that is able to oxidize phenolic and non-phenolic aromatics, Mn2+, and different dyes. The ability of VP from Pleurotus eryngii to oxidize water-soluble lignins (softwood and hardwood lignosulfonates) is demonstrated here by a combination of directed mutagenesis and spectroscopic techniques, among others. In addition, direct electron transfer between the peroxidase and the lignin macromolecule was kinetically characterized using stopped-flow spectrophotometry. VP variants were used to show that this reaction strongly depends on the presence of a solvent-exposed tryptophan residue (Trp-164). Moreover, the tryptophanyl radical detected by EPR spectroscopy of H2O2-activated VP (being absent from the W164S variant) was identified as catalytically active because it was reduced during lignosulfonate oxidation, resulting in the appearance of a lignin radical. The decrease of lignin fluorescence (excitation at 355 nm/emission at 400 nm) during VP treatment under steady-state conditions was accompanied by a decrease of the lignin (aromatic nuclei and side chains) signals in one-dimensional and two-dimensional NMR spectra, confirming the ligninolytic capabilities of the enzyme. Simultaneously, size-exclusion chromatography showed an increase of the molecular mass of the modified residual lignin, especially for the (low molecular mass) hardwood lignosulfonate, revealing that the oxidation products tend to recondense during the VP treatment. Finally, mutagenesis of selected residues neighboring Trp-164 resulted in improved apparent second-order rate constants for lignosulfonate reactions, revealing that changes in its protein environment (modifying the net negative charge and/or substrate accessibility/binding) can modulate the reactivity of the catalytic tryptophan. PMID:26240145

Optimizing optical pre-dispersion using transmit DSP for mitigation of Kerr nonlinearities in dispersion managed cables

Science.gov (United States)

Hopkins, James; Gaudette, Jamie; Mehta, Priyanth

2013-10-01

With the advent of digital signal processing (DSP) in optical transmitters and receivers, the ability to finely tune the ratio of pre and post dispersion compensation can be exploited to best mitigate the nonlinear penalties caused by the Kerr effect. A portion of the nonlinear penalty in optical communication channels has been explained by an increase in peak to average power ratio (PAPR) inherent in highly dispersed signals. The standard approach for minimizing these impairments applies 50% pre dispersion compensation and 50% post dispersion compensation, thereby decreasing average PAPR along the length of the cable, as compared with either 100% pre or post dispersion compensation. In this paper we demonstrate that simply considering the net accumulated dispersion, and applying 50/50 pre/post dispersion is not necessarily the best way to minimize PAPR and subsequent Kerr nonlinearities. Instead, we consider the cumulative dispersion along the entire length of the cable, and, taking into account this additional information, derive an analytic formula for the minimization of PAPR. Alignment with simulation and experimental measurements is presented using a commercially available 100Gb/s dual-polarization binary phase-shift-keying (DP-BPSK) coherent modem, with transmitter and receiver DSP. Measurements are provided from two different 5000km dispersion managed Submarine test-beds, as well as a 3800km terrestrial test-bed with a mixture of SMF-28 and TWRS optical fiber. This method is shown to deviate significantly from the conventional 50/50 method described above, in dispersion managed communications systems, and more closely aligns with results obtained from simulation and data collected from laboratory test-beds.

A comparison of various modes of liquid-liquid based microextraction techniques: determination of picric acid.

Science.gov (United States)

Burdel, Martin; Šandrejová, Jana; Balogh, Ioseph S; Vishnikin, Andriy; Andruch, Vasil

2013-03-01

Three modes of liquid-liquid based microextraction techniques--namely auxiliary solvent-assisted dispersive liquid-liquid microextraction, auxiliary solvent-assisted dispersive liquid-liquid microextraction with low-solvent consumption, and ultrasound-assisted emulsification microextraction--were compared. Picric acid was used as the model analyte. The determination is based on the reaction of picric acid with Astra Phloxine reagent to produce an ion associate easily extractable by various organic solvents, followed by spectrophotometric detection at 558 nm. Each of the compared procedures has both advantages and disadvantages. The main benefit of ultrasound-assisted emulsification microextraction is that no hazardous chlorinated extraction solvents and no dispersive solvent are necessary. Therefore, this procedure was selected for validation. Under optimized experimental conditions (pH 3, 7 × 10(-5) mol/L of Astra Phloxine, and 100 μL of toluene), the calibration plot was linear in the range of 0.02-0.14 mg/L and the LOD was 7 μg/L of picric acid. The developed procedure was applied to the analysis of spiked water samples. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Metal-Free Aqueous Flow Battery with Novel Ultrafiltered Lignin as Electrolyte

Energy Technology Data Exchange (ETDEWEB)

Mukhopadhyay, Alolika [Department of Mechanical and Industrial Engineering, Northeastern University, 360 Huntington Avenue, 334 Snell Engineering, Boston, Massachusetts 02115, United States; Hamel, Jonathan [Department of Mechanical and Industrial Engineering, Northeastern University, 360 Huntington Avenue, 334 Snell Engineering, Boston, Massachusetts 02115, United States; Katahira, Rui [National Renewable Energy Laboratory, Denver West Parkway, Golden, Colorado 80401, United States; Zhu, Hongli [Department of Mechanical and Industrial Engineering, Northeastern University, 360 Huntington Avenue, 334 Snell Engineering, Boston, Massachusetts 02115, United States

2018-03-05

As the number of generation sources from intermittent renewable technologies on the electric grid increases, the need for large-scale energy storage devices is becoming essential to ensure grid stability. Flow batteries offer numerous advantages over conventional sealed batteries for grid storage. In this work, for the first time, we investigated lignin, the second most abundant wood derived biopolymer, as an anolyte for the aqueous flow battery. Lignosulfonate, a water-soluble derivative of lignin, is environmentally benign, low cost and abundant as it is obtained from the byproduct of paper and biofuel manufacturing. The lignosulfonate utilizes the redox chemistry of quinone to store energy and undergoes a reversible redox reaction. Here, we paired lignosulfonate with Br2/Br-, and the full cell runs efficiently with high power density. Also, the large and complex molecular structure of lignin considerably reduces the electrolytic crossover, which ensures very high capacity retention. The flowcell was able to achieve current densities of up to 20 mA/cm2 and charge polarization resistance of 15 ohm cm2. This technology presents a unique opportunity for a low-cost, metal-free flow battery capable of large-scale sustainable energy storage.

Preparation and Evaluation of Newly Developed Chitosan Salt Coating Dispersions for Colon Delivery without Requiring Overcoating.

Science.gov (United States)

Yamada, Kyohei; Iwao, Yasunori; Bani-Jaber, Ahmad; Noguchi, Shuji; Itai, Shigeru

2015-01-01

Although chitosan (CS) has been recognized as a good material for colon-specific drug delivery systems, an overcoating with an enteric coating polymer on the surface of CS is absolutely necessary because CS is soluble in acidic conditions before reaching the colon. In the present study, to improve its stability in the presence of acid, a newly developed CS-laurate (CS-LA) material was evaluated as a coating dispersion for the development of colon-specific drug delivery systems. Two types of CS with different molecular weights, CS250 and CS600, were used to prepare CS-LA films by the casting method. The CS250-LA films had smooth surfaces, whereas the surfaces of the CS600-LA films were rough, indicating that the CS250-LA dispersion could form a denser film than CS600-LA. Both of these CS-LA films maintained a constant shape over 22 h in a pH 1.2 HCl/NaCl buffer, where the corresponding CS films rapidly disintegrated. In addition, the CS250-LA film showed specific colon degradability in a pH 6.0 phosphate buffered solution containing 1.0% (w/v) β-glucosidase. As a result of tensile strength and elongation at the break, both CS-LA films were found to have flexible film properties. Finally, the release of acetaminophen from disks coated with CS250-LA dispersions was significantly suppressed in fluids at pH 1.2 and 6.8, whereas disks coated with CS solution rapidly released the drug in pH 1.2 fluids. Taken together, this study shows that LA modification could be a useful approach in preparing CS films with acid stability and colonic degradability properties without requiring overcoating.

Increases of QT dispersion, corrected QT dispersion and QT interval in young healthy individuals during Ramadan fasting

Directory of Open Access Journals (Sweden)

Moradmand S

2003-06-01

Full Text Available Ramadan fasting is one of the most important religious duties of Muslims, that its effect on the heart has not been determined yet. Our objective was to evaluate the effect of Ramadan fasting on ventricular repolarization as assessed by QT interval, corrected QT interval, QT dispersion or corrected QT dispersion. Sixthy healthy subjects aged 20 to 35 years were dispersion included in this study. QT interval, corrected QT interval (QTc QT dispersion QTc dispersion, RR interval and QRS axis were measured in 12-lead surface electrocardiogram, once during fasting (10 to 11.5 hours of absolute fasting from food and liquid and another time, 15 tp 60 minutes after eating food at sunset, All of the subjects had been fasting 11 to 12 hours each day at least for 25 days during Ramadan. The study was performed at Amir Alam hospital in the year 2000. Maximal QT interval, mean QT interval and RR-interval, were longer during fasting (P<0.05, and both QT dispersion and QTc dispersion were increased (P<0.05. (QT dispersion: mean ±SD= 57.2±20.1 ms during fasting Vs 41.6±15.1 ms after meal, QTc dispersion=75.4±24.6 ms during fasting Vs 64.1±22.8 ms after meal. But mean QTc interval maximal QTc interval and QRS axis showed no significant difference. Prolongation of QT interval and RR interval during fasting, instead of no significant changes in corrected QT interval may primarily suggest that prolongation of RR-interval causes QTc interval not to have significant difference. But increases of QT dispersion and corrected QT dispersion (QTc dispersion during fasting -that are more reliable indicators of ventricular repolarization-support the idea that ventricular repolarization may be changed during Ramadan fasting. QT dispersion in cardiac patients is showed to increase from normal values of 30-40 to 64-138 ms, but in our study their increases did not reach critical value.

Direct generation of titanium dioxide nanoparticles dispersion under supercritical conditions for photocatalytic active thermoplastic surfaces for microbiological inactivation

International Nuclear Information System (INIS)

Zydziak, Nicolas; Zanin, Maria-Helena Ambrosio; Trick, Iris; Hübner, Christof

2015-01-01

Thermoplastic poly(propylene) (PP) and acrylonitrile-butadiene-styrene (ABS) surfaces were coated with silica based films via the sol–gel process, containing titanium dioxide (TiO 2 ) as photocatalyst. TiO 2 was previously synthesized via sol–gel and treated under supercritical conditions in water dispersions. The characterization of the TiO 2 dispersions was performed via disc centrifuge to determine the particle size and via Raman spectroscopy and X-Ray Diffraction (XRD) to characterize the crystallinity of TiO 2 . The synthesized TiO 2 dispersions and commercially available TiO 2 particles were incorporated in silica based films which were synthesized under acidic or basic conditions, leading to dense or porous films respectively. The morphology of the films was characterized via Scanning Electron Microscopy (SEM). The incorporation of synthesized TiO 2 in the coating led to photocatalytically more active thermoplastic surfaces than films formulated with commercially available TiO 2 as determined via dye discoloration test. A microbiological test performed with Sarcina lutea confirmed this result and showed an inactivation factor of 6 (99.9999%) after 24 h UV irradiation, for synthesized TiO 2 incorporated in acidic formulated silica layer on ABS surfaces. - Highlights: • We report about photocatalytic layers formulated on thermoplastic surfaces. • We synthesized silica layer and TiO 2 via sol–gel and supercritical treatment. • Amorphous, crystalline and commercial dispersions were generated and characterized. • The morphology of dense and porous photocatalytic layers is observed via SEM. • Discoloration and microbiological tests correlate activity and surface morphology

Dispersion Distance and the Matter Distribution of the Universe in Dispersion Space.

Science.gov (United States)

Masui, Kiyoshi Wesley; Sigurdson, Kris

2015-09-18

We propose that "standard pings," brief broadband radio impulses, can be used to study the three-dimensional clustering of matter in the Universe even in the absence of redshift information. The dispersion of radio waves as they travel through the intervening plasma can, like redshift, be used as a cosmological distance measure. Because of inhomogeneities in the electron density along the line of sight, dispersion is an imperfect proxy for radial distance and we show that this leads to calculable dispersion-space distortions in the apparent clustering of sources. Fast radio bursts (FRBs) are a new class of radio transients that are the prototypical standard ping and, due to their high observed dispersion, have been interpreted as originating at cosmological distances. The rate of fast radio bursts has been estimated to be several thousand over the whole sky per day and, if cosmological, the sources of these events should trace the large-scale structure of the Universe. We calculate the dispersion-space power spectra for a simple model where electrons and FRBs are biased tracers of the large-scale structure of the Universe, and we show that the clustering signal could be measured using as few as 10 000 events. Such a survey is in line with what may be achieved with upcoming wide-field radio telescopes.

Normal-dispersion microresonator Kerr frequency combs

Directory of Open Access Journals (Sweden)

Xue Xiaoxiao

2016-06-01

Full Text Available Optical microresonator-based Kerr frequency comb generation has developed into a hot research area in the past decade. Microresonator combs are promising for portable applications due to their potential for chip-level integration and low power consumption. According to the group velocity dispersion of the microresonator employed, research in this field may be classified into two categories: the anomalous dispersion regime and the normal dispersion regime. In this paper, we discuss the physics of Kerr comb generation in the normal dispersion regime and review recent experimental advances. The potential advantages and future directions of normal dispersion combs are also discussed.

Dispersion modeling by kinematic simulation: Cloud dispersion model

International Nuclear Information System (INIS)

Fung, J C H; Perkins, R J

2008-01-01

A new technique has been developed to compute mean and fluctuating concentrations in complex turbulent flows (tidal current near a coast and deep ocean). An initial distribution of material is discretized into any small clouds which are advected by a combination of the mean flow and large scale turbulence. The turbulence can be simulated either by kinematic simulation (KS) or direct numerical simulation. The clouds also diffuse relative to their centroids; the statistics for this are obtained from a separate calculation of the growth of individual clouds in small scale turbulence, generated by KS. The ensemble of discrete clouds is periodically re-discretized, to limit the size of the small clouds and prevent overlapping. The model is illustrated with simulations of dispersion in uniform flow, and the results are compared with analytic, steady state solutions. The aim of this study is to understand how pollutants disperses in a turbulent flow through a numerical simulation of fluid particle motion in a random flow field generated by Fourier modes. Although this homogeneous turbulent is rather a 'simple' flow, it represents a building block toward understanding pollutant dispersion in more complex flow. The results presented here are preliminary in nature, but we expect that similar qualitative results should be observed in a genuine turbulent flow.

Synthesis and characterization of 12-phosphotungstic acid supported on BEA zeolite

Energy Technology Data Exchange (ETDEWEB)

Jović, A.; Bajuk-Bogdanović, D.; Nedić Vasiljević, B. [Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, 11000 Belgrade (Serbia); Milojević-Rakić, M., E-mail: maja@ffh.bg.ac.rs [Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, 11000 Belgrade (Serbia); Krajišnik, D. [Department of Pharmaceutical Technology and Cosmetology, University of Belgrade-Faculty of Pharmacy, Vojvode Stepe 450, 11000 Belgrade (Serbia); Dondur, V. [Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, 11000 Belgrade (Serbia); Popa, A. [Institute of Chemistry Timisoara, Bl. Mihai Viteazul 24, 300223 Timisoara (Romania); Uskoković-Marković, S. [Department of Analytical Chemistry, University of Belgrade-Faculty of Pharmacy, Vojvode Stepe 450, 11000 Belgrade (Serbia); Holclajtner-Antunović, I. [Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, 11000 Belgrade (Serbia)

2017-01-15

An optimized synthetic route for obtaining heteropoly acid (HPA) species supported on BEA zeolite was applied, and different samples, comprising 20 to 50 wt% of 12-phosphotungstic acid (HPW) were prepared. The as-synthesized supported HPW were subjected to different post-synthesis routes, which involved calcination and ultrasound treatment. Characterization of these materials was performed by means of Scanning Electron Microscopy, zeta potential measurements, Infrared Spectroscopy and X-ray Powder Diffraction analysis. Results suggest strong interaction of HPW with the support and revealed that ultrasound treatment resulted in better dispersion of active phase and thus homogeneous morphology of the samples. The zeta potential was found to be dependent on the preparation procedure and HPW content in these materials, while higher HPW loadings induced its agglomeration. Catalytic activity of the synthesized materials was investigated in an ethanol dehydration reaction, where lower HPW loadings induced higher ethanol conversion. Acid sites distribution and accessibility for ethanol molecules were found to be more essential for catalytic activity than HPW loadings, i.e., amount of active sites present in these hybrid materials. - Highlights: • An optimized route for supporting heteropoly acid on beta zeolite is applied. • Ultrasound treatment of the composites gives dispersed morphology. • Lower heteropoly acid amount induces higher conversion in ethanol dehydration. • Acid sites distribution and accessibility for ethanol are essential for catalytic activity.

Synthesis and characterization of 12-phosphotungstic acid supported on BEA zeolite

International Nuclear Information System (INIS)

Jović, A.; Bajuk-Bogdanović, D.; Nedić Vasiljević, B.; Milojević-Rakić, M.; Krajišnik, D.; Dondur, V.; Popa, A.; Uskoković-Marković, S.; Holclajtner-Antunović, I.

2017-01-01

An optimized synthetic route for obtaining heteropoly acid (HPA) species supported on BEA zeolite was applied, and different samples, comprising 20 to 50 wt% of 12-phosphotungstic acid (HPW) were prepared. The as-synthesized supported HPW were subjected to different post-synthesis routes, which involved calcination and ultrasound treatment. Characterization of these materials was performed by means of Scanning Electron Microscopy, zeta potential measurements, Infrared Spectroscopy and X-ray Powder Diffraction analysis. Results suggest strong interaction of HPW with the support and revealed that ultrasound treatment resulted in better dispersion of active phase and thus homogeneous morphology of the samples. The zeta potential was found to be dependent on the preparation procedure and HPW content in these materials, while higher HPW loadings induced its agglomeration. Catalytic activity of the synthesized materials was investigated in an ethanol dehydration reaction, where lower HPW loadings induced higher ethanol conversion. Acid sites distribution and accessibility for ethanol molecules were found to be more essential for catalytic activity than HPW loadings, i.e., amount of active sites present in these hybrid materials. - Highlights: • An optimized route for supporting heteropoly acid on beta zeolite is applied. • Ultrasound treatment of the composites gives dispersed morphology. • Lower heteropoly acid amount induces higher conversion in ethanol dehydration. • Acid sites distribution and accessibility for ethanol are essential for catalytic activity.

Acid–base interaction between carbon black and polyurethane molecules with different amine values: Dispersion stability of carbon black suspension for use in lithium ion battery cathodes

International Nuclear Information System (INIS)

Kil, Ki Chun; Kim, Gu Yeon; Cho, Chae-Woong; Lim, Myung Duk; Kim, Kijun; Jeong, Kyung-Min; Lee, Jinuk; Paik, Ungyu

2013-01-01

The dispersion properties of carbon black (CB) slurries as well as the accompanying electrochemical properties of Li(Ni 1/3 Co 1/3 Mn 1/3 )O 2 (NCM) electrodes were investigated by controlling the amine value of polyurethane-based dispersants. The increase in amine value of dispersants leads to an increase in adsorption level on CB surface due to a strong acid/base interaction between dispersants and CB particles, providing the improvement of steric repulsion between particles at the solid–liquid interface. This results in the enhancement of the dispersion stability of CB and the related microstructure of the electrodes. Electrochemical experiments indicated that the rate capabilities and cycle performance of the electrodes are in good agreement with dispersion properties of CB slurries. However, it was found that the excessive addition of the dispersant was deleterious to electrochemical properties because the non-adsorbed dispersants act as an electronic conduction barrier between solid phases. Therefore, it is suggested that the amine value of dispersant and tailored amount of dispersant addition can be key roles for obtaining the optimized dispersion stability of CB and the corresponding excellent electrochemical properties of the cathode

Investigating uptake of water-dispersible CdSe/ZnS quantum dot nanoparticles by Arabidopsis thaliana plants

International Nuclear Information System (INIS)

Navarro, Divina A.; Bisson, Mary A.; Aga, Diana S.

2012-01-01

Graphical abstract: This study highlights the importance of quantum dot (QD) structural stability in preventing phytotoxicity. Overall, there is no evidence that Arabidopsis thaliana plants can internalize intact QDs within 1–7 days of exposure, with or without humic acids. Highlights: ► Potential uptake of water-dispersible CdSe/ZnS QDs by Arabidopsis was demonstrated. ► QDs were not internalized by Arabidopsis as intact particles. ► Plants exposed to Cd-, Se-, and QD + HA suspensions experienced oxidative stress. ► An effective LC–MS method proves detection of low levels of glutathione in plants. ► Uptake of Cd and/or Se leached from QDs is of major concern. - Abstract: Interest on the environmental impacts of engineered nanomaterials has rapidly increased over the past years because it is expected that these materials will eventually be released into the environment. The present work investigates the potential root uptake of water-dispersible CdSe/ZnS quantum dots (QDs) by the model plant species, Arabidopsis thaliana. Experiments revealed that Arabidopsis exposed to QDs that are dispersed in Hoagland's solution for 1–7 days did not internalize intact QDs. Analysis of Cd and Se concentrations in roots and leaves by inductively-coupled plasma mass spectrometry indicated that Cd and Se from QD-treated plants were not translocated into the leaves, and remained in the root system of Arabidopsis. Furthermore, fluorescence microscopy showed strong evidence that the QDs were generally on the outside surfaces of the roots, where the amount of QDs adsorbed is dependent on the stability of the QDs in suspension. Despite no evidence of nanoparticle internalization, the ratio of reduced glutathione levels (GSH) relative to the oxidized glutathione (GSSG) in plants decreased when plants were exposed to QD dispersions containing humic acids, suggesting that QDs caused oxidative stress on the plant at this condition.

UV curable aqueous dispersions for wood coatings

International Nuclear Information System (INIS)

Peeters, S.; Bleus, J.P.; Wang, Z.J.; Arceneaux, J. A.; Hall, J.

1999-01-01

In this paper the characterisation of aqueous dispersions of UV curable resins is described. Two types of dispersions were used: dispersions that are tacky after water evaporation and tack - free before cure dispersions. The physical and rheological properties of these products have been determined and the performance of these dispersions in various formulations, especially for wood applications has been studied. With these dispersions, it is possible to produce coatings having a good cure speed, good surface hardness and good solvent -, chemical - and water resistance

Potential of dispersion of Tecoma stans and chemical attributes of some soils of the Paraná state

Directory of Open Access Journals (Sweden)

Celina Wisniewski

2009-03-01

Full Text Available This work correlated invasiveness characteristic (potential dispersion of Tecoma stans (L. Jussieu ex. Kunth(BIGNONIACEAE known as a Yellow-Bell. Open field test was developed starting from stakes in vases with four different types soilsof the Paraná State, conduced to randomized block design with four treatments and five replications. The soils were analyzedregarding the pH, CTC, level of C, Al+³, macro and micronutrients, and content of sand, silt and clay. After 6 months the leaf area, dryweight of leaves and potential dispersion, calculated by given numeric values from 1 to 4 for phonological phases presented. Themacro and micronutrients content (except K and Fe were high in all the soils. The correlations between dispersion potential and pHand the V% were positive and significant and with effective CTC, the Fe and clay content were negative. It was not found significantcorrelations between the dispersion potential and biomass or leaf area. Positive and significant correlations of biomass and leaf areawith macro (except P and micronutrients (except Cu apparently indicate that if the evaluation had been accomplished at the end of theflowering period of the species, nutritional relationships with the dispersion potential would be clearer, although it can be concludedthat the species has a preference for less acid soils.

Catchment Dispersion Mechanisms in an Urban Context

Science.gov (United States)

Gironas, J. A.; Mejia, A.; Rossel, F.; Rinaldo, A.; Rodriguez, F.

2014-12-01

Dispersion mechanisms have been examined in-depth in natural catchments in previous studies. However, these dispersion mechanisms have been studied little in urban catchments, where artificial transport elements and morphological arrangements are expected to modify travel times and mobilize excess rainfall from spatially distributed impervious sites. Thus, these features can modify the variance of the catchment's travel times and hence the total dispersion. This work quantifies the dispersion mechanisms in an urban catchment using the theory of transport by travel times as represented by the Urban Morpho-climatic Instantaneous Unit Hydrograph (U-McIUH) model. This model computes travel times based on kinematic wave theory and accounts explicitly for the path heterogeneities and altered connectivity patterns characteristic of an urban drainage network. The analysis is illustrated using the Aubinière urban catchment (France) as a case study. We found that kinematic dispersion is dominant for small rainfall intensities, whereas geomorphologic dispersion becomes more dominant for larger intensities. The total dispersion scales with the drainage area in a power law fashion. The kinematic dispersion is dominant across spatial scales up to a threshold of approximately 2-3 km2, after which the geomorphologic dispersion becomes more dominant. Overall, overland flow is responsible for most of the dispersion, while conduits tend to counteract the increase of the geomorphologic dispersion with a negative kinematic dispersion. Further studies with other catchments are needed to assess whether the latter is a general feature of urban drainage networks.

Reactimeter dispersion equation

OpenAIRE

A.G. Yuferov

2016-01-01

The aim of this work is to derive and analyze a reactimeter metrological model in the form of the dispersion equation which connects reactimeter input/output signal dispersions with superimposed random noise at the inlet. It is proposed to standardize the reactimeter equation form, presenting the main reactimeter computing unit by a convolution equation. Hence, the reactimeter metrological characteristics are completely determined by this unit hardware function which represents a transient re...

Dispersal and biogeography of silica-scaled chrysophytes

DEFF Research Database (Denmark)

Kristiansen, Jørgen

2008-01-01

The silica-scaled chrysophytes—here mainly represented by the freshwater genera Mallomonas and Synura—have special problems in dispersal from one habitat to another because they cannot tolerate desiccation. Their dispersal is limited by the fragile construction and aquatic habit. Dispersal from one...... water body to another involves dangerous changes of the environment, and the ability to avoid desiccation during transport is crucial. So, air-borne and ectozoic dispersal by birds or mammals can only work at short distances. This danger may be avoided by endozoic dispersal of thick-walled cysts; as far....... The distribution of a species at a given time depends on several factors: dispersal capacity—available vectors—suitable available habitats—and most important: sufficient time for dispersal. It is remarkable that the chrysophytes—in spite of their fragile cell construction and apparently low dispersal capacity...

Evaluating the graphene oxide dispersions for Fish Embryo Toxicity (FET) test

Energy Technology Data Exchange (ETDEWEB)

Clemente, Zaira; Franqui, Lidiane; Silva, Cristiane A.; Martinez, Diego Stefani Teodoro, E-mail: zairaclemente@hotmail.com [Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, SP (Brazil); Castro, Vera Lucia Scherholz Salgado [Empresa Brasileira de Pesquisa Agropecuaria (EMBRAPA), Campinhas, SP (Brazil)

2016-07-01

Full text: The Fish Embryo Toxicity (FET) test has wide utilization in nano ecotoxicology. However, some difficulties have been found related to the aggregation and precipitation of nanomaterials in exposure medium and the contrasting results among studies due to differences in the material characteristics. Furthermore, abiotic factors as the presence of organic matter can influence the test evaluation. The aim of this study was to evaluate and characterize the effect of the humic acid presence in the stability of two types of graphene oxide dispersion in an exposure medium used in FET test. Stock-suspensions (1.0 mg mL{sup -1}) of GO (sigma Aldrich, flakes) or base-washed GO (bwGO) and humic acid (HA sodium salt, Sigma Aldrich) were prepared in ultrapure water (UW). They were sonicated before preparing the GO or bwGO test suspensions at 100.0 μg mL{sup -1} in UW and reconstituted water (RW, pH 8±0.2, 425±129 μS/cm), with HA (20.0 μg mL{sup -1})or not. The samples were incubated during 96h at 26 deg C. The GO and bwGO and its dispersions were characterized through the following techniques: spectrophotometry, centrifugation, dynamic light scattering (DLS), nanoparticle tracking analysis (NTA), thermogravimetry (TGA), and X-ray photoelectron spectrometry (XPS). The results showed that materials aggregated and precipitated quickly in RW, but in the presence of HA the stability was similar to that found in UW. The aggregation and precipitation of bwGO was more intense than that of GO. The bwGO showed a great particle sizes heterogeneity than GO, in any condition tested. The different behavior can be related to the less presence of oxygenated groups in bwGO regards to GO. These results showed that surface characteristic of GO and the presence of HA influence the GO behavior in exposure medium and support the use of HA as a natural dispersant to graphene oxide in FET test. (author)

Long range transport of air pollutants in Europe and acid precipitation in Norway

Science.gov (United States)

Jack Nordo

1976-01-01

Observations show that pollutants from large emission sources may cause significant air concentrations 500 to 1000 miles away. Very acid precipitation occurs in such periods. The scavenging is often intensified by the topography. Case studies will be presented, with special emphasis on acid precipitation in Scandinavia. Large scale dispersion models have been developed...

Enhanced Bioaccessibility of Curcuminoids in Buttermilk Yogurt in Comparison to Curcuminoids in Aqueous Dispersions.

Science.gov (United States)

Fu, Shishan; Augustin, Mary Ann; Sanguansri, Luz; Shen, Zhiping; Ng, Ken; Ajlouni, Said

2016-03-01

Curcuminoids have low bioavailability due to low aqueous solubility. We compared the bioaccessibility of curcuminoids delivered in buttermilk yogurt to that of curcuminoid powder in an aqueous dispersion. Buttermilk containing added curcuminoids (300 mg/100 g, 0.3% w/w) was used for yogurt manufacture. We measured percentage of curcuminoids remaining in yogurts after manufacture and after exposure to simulated gastrointestinal fluids, and the in vitro bioaccessibility of the curcuminoids. Curcuminoids were stable during yogurt manufacture. At the end of in vitro digestion, approximately 11% of the curcuminoids delivered in yogurt was degraded compared to yogurt was 15-fold more bioaccessible than curcuminoids in aqueous dispersion. The small change in yogurt properties (decrease in total lactic acid bacteria counts of yogurts. © 2016 Institute of Food Technologists®

Dynamics of Dispersive Wave Generation in Gas-Filled Photonic Crystal Fiber with the Normal Dispersion

Directory of Open Access Journals (Sweden)

Zhixiang Deng

2017-01-01

Full Text Available The absence of Raman and unique pressure-tunable dispersion is the characteristic feature of gas-filled photonic crystal fiber (PCF, and its zero dispersion points can be extended to the near-infrared by increasing gas pressure. The generation of dispersive wave (DW in the normal group velocity dispersion (GVD region of PCF is investigated. It is demonstrated that considering the self-steepening (SS and introducing the chirp of the initial input pulse are two suitable means to control the DW generation. The SS enhances the relative average intensity of blue-shift DW while weakening that of red-shift DW. The required propagation distance of DW emission is markedly varied by introducing the frequency chirp. Manipulating DW generation in gas-filled PCF by the combined effects of either SS or chirp and three-order dispersion (TOD provides a method for a concentrated transfer of energy into the targeted wavelengths.

Synthesis of Ricinoleic Acid Estolides by the Esterification of Ricinoleic Acids Using Functional Acid Ionic Liquids as Catalysts.

Science.gov (United States)

Wang, Gaoshang; Sun, Shangde

2017-07-01

Estolides of ricinoleic acid (RA) have been used as lubricants and pigment dispersant in many industries. In this paper, functional acid ionic liquids (ILs) were firstly used as catalysts to prepare RA estolides by the esterification of RAs in solvent-free system. Different ILs were used as catalysts for the esterification. Effect of reaction variables (IL amount, reaction temperature and reaction time) on the esterification were also investigated and optimized using response surface methodology (RSM). Among all tested ILs, [BSO 3 HMIM]TS showed the best performance for the esterification. Arrhenius equation for the esterification was lnV 0 =14.897-7558.7/T, and the activation energy (Ea) was 62.84 kJ/mol. A high degree of polymerization with an acid value of 48.0±2.5 mg KOH/g was achieved at the optimized conditions (IL load 12%, reaction temperature 140°C, and reaction time 12 h). The effect of reaction variables on the esterification decreased in the order of catalyst loading of IL > reaction temperature > reaction time.

Nanoparticle dispersion in environmentally relevant culture media: a TiO2 case study and considerations for a general approach

International Nuclear Information System (INIS)

Horst, Allison M.; Ji, Zhaoxia; Holden, Patricia A.

2012-01-01

Nanoparticle exposure in toxicity studies requires that nanoparticles are bioavailable by remaining highly dispersed in culture media. However, reported dispersion approaches are variable, mostly study-specific, and not transferable owing to their empirical basis. Furthermore, many published approaches employ proteinaceous dispersants in rich laboratory media, both of which represent end members in environmental scenarios. Here, a systematic approach was developed to disperse initially agglomerated TiO 2 nanoparticles (Aeroxide® TiO 2 P25, Evonik, NJ; primary particle size range 6.4–73.8 nm) in oligotrophic culture medium for environmentally relevant bacterial toxicity studies. Based on understanding particle–particle interactions in aqueous media and maintaining environmental relevance, the approach involves (1) quantifying the relationship between pH and zeta potential to determine the point of zero charge of select nanoparticles in water; (2) nominating, then testing and selecting, environmentally relevant stabilizing agents; and (3) dispersing via “condition and capture” whereby stock dry powder nanoparticles are sonicated in pre-conditioned (with base, or acid, plus stabilizing agent) water, then diluted into culture media. The “condition and capture” principle is transferable to other nanoparticle and media chemistries: simultaneously, mechanically and electrostatically, nanoparticles can be dispersed with surrounding stabilizers that coat and sterically hinder reagglomeration in the culture medium.

Oak Dispersal Syndromes: Do Red and White Oaks Exhibit Different Dispersal Srategies?

Science.gov (United States)

Michael Steele; Peter Smallwood; William B. Terzaghi; John E. Carlson; Thomas conteras; Amy McEuen

2004-01-01

We provide an overview of the ecological and evolutionary interactions between oaks and several of their dispersal agents, and review a series of studies that demonstrate how various acorn characteristics affect feeding and caching decisions of these animals, which in turn may influence oak dispersal and establishment. We demonstrate that acorns of red oak species show...

The dispersion of SWCNTs treated by coupling and dispersing agents in fiber reinforced polymer composities

Science.gov (United States)

Duan, Yuexin; Yuan, Lu; Zhao, Yan; Guan, Fengxia

2007-07-01

It is an obstacle issue for Carbon nanotubes (CNTs) applied in fiber reinforced polymer composites that CNTs is dispersed in nano-level, particularly for single-wall Carbon nanotubes (SWCNTs). In this paper, SWCNTs were treated by the coupling agent like volan and dispersing agent as BYK to improve the dispersion in the Glass Fiber/Epoxy composites. The result of dispersion of SWCNTs in composites was observed by Scanning electron microscopy (SEM). Then the Glass Transition Temperature (Tg) of these kinds of composites with treated and untreated SWCNTs were obtained by Dynamic Mechanical Thermal Analysis (DMTA). Moreover, the bending properties of these composites were tested.

Extragalactic dispersion measures of fast radio bursts

International Nuclear Information System (INIS)

Xu, Jun; Han, J. L.

2015-01-01

Fast radio bursts show large dispersion measures, much larger than the Galactic dispersion measure foreground. Therefore, they evidently have an extragalactic origin. We investigate possible contributions to the dispersion measure from host galaxies. We simulate the spatial distribution of fast radio bursts and calculate the dispersion measures along the sightlines from fast radio bursts to the edge of host galaxies by using the scaled NE2001 model for thermal electron density distributions. We find that contributions to the dispersion measure of fast radio bursts from the host galaxy follow a skew Gaussian distribution. The peak and the width at half maximum of the dispersion measure distribution increase with the inclination angle of a spiral galaxy, to large values when the inclination angle is over 70°. The largest dispersion measure produced by an edge-on spiral galaxy can reach a few thousand pc cm −3 , while the dispersion measures from dwarf galaxies and elliptical galaxies have a maximum of only a few tens of pc cm −3 . Notice, however, that additional dispersion measures of tens to hundreds of pc cm −3 can be produced by high density clumps in host galaxies. Simulations that include dispersion measure contributions from the Large Magellanic Cloud and the Andromeda Galaxy are shown as examples to demonstrate how to extract the dispersion measure from the intergalactic medium. (paper)

Many-body dispersion effects in the binding of adsorbates on metal surfaces

Energy Technology Data Exchange (ETDEWEB)

Maurer, Reinhard J. [Department of Chemistry, Yale University, New Haven, Connecticut 06520 (United States); Ruiz, Victor G.; Tkatchenko, Alexandre [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin (Germany)

2015-09-14

A correct description of electronic exchange and correlation effects for molecules in contact with extended (metal) surfaces is a challenging task for first-principles modeling. In this work, we demonstrate the importance of collective van der Waals dispersion effects beyond the pairwise approximation for organic–inorganic systems on the example of atoms, molecules, and nanostructures adsorbed on metals. We use the recently developed many-body dispersion (MBD) approach in the context of density-functional theory [Tkatchenko et al., Phys. Rev. Lett. 108, 236402 (2012) and Ambrosetti et al., J. Chem. Phys. 140, 18A508 (2014)] and assess its ability to correctly describe the binding of adsorbates on metal surfaces. We briefly review the MBD method and highlight its similarities to quantum-chemical approaches to electron correlation in a quasiparticle picture. In particular, we study the binding properties of xenon, 3,4,9,10-perylene-tetracarboxylic acid, and a graphene sheet adsorbed on the Ag(111) surface. Accounting for MBD effects, we are able to describe changes in the anisotropic polarizability tensor, improve the description of adsorbate vibrations, and correctly capture the adsorbate–surface interaction screening. Comparison to other methods and experiment reveals that inclusion of MBD effects improves adsorption energies and geometries, by reducing the overbinding typically found in pairwise additive dispersion-correction approaches.

Inhibition and dispersal of Agrobacterium tumefaciens biofilms by a small diffusible Pseudomonas aeruginosa exoproduct(s).

Science.gov (United States)

Hibbing, Michael E; Fuqua, Clay

2012-06-01

Environmental biofilms often contain mixed populations of different species. In these dense communities, competition between biofilm residents for limited nutrients such as iron can be fierce, leading to the evolution of competitive factors that affect the ability of competitors to grow or form biofilms. We have discovered a compound(s) present in the conditioned culture fluids of Pseudomonas aeruginosa that disperses and inhibits the formation of biofilms produced by the facultative plant pathogen Agrobacterium tumefaciens. The inhibitory activity is strongly induced when P. aeruginosa is cultivated in iron-limited conditions, but it does not function through iron sequestration. In addition, the production of the biofilm inhibitory activity is not regulated by the global iron regulatory protein Fur, the iron-responsive extracytoplasmic function σ factor PvdS, or three of the recognized P. aeruginosa quorum-sensing systems. In addition, the compound(s) responsible for the inhibition and dispersal of A. tumefaciens biofilm formation is likely distinct from the recently identified P. aeruginosa dispersal factor, cis-2-decenoic acid (CDA), as dialysis of the culture fluids showed that the inhibitory compound was larger than CDA and culture fluids that dispersed and inhibited biofilm formation by A. tumefaciens had no effect on biofilm formation by P. aeruginosa.

Development and evaluation of gastroretentive raft forming systems incorporating curcumin-Eudragit® EPO solid dispersions for gastric ulcer treatment.

Science.gov (United States)

Kerdsakundee, Nattha; Mahattanadul, Sirima; Wiwattanapatapee, Ruedeekorn

2015-08-01

Novel raft forming systems incorporating curcumin-Eudragit® EPO solid dispersions were developed to prolong the gastric residence time and provide for a controlled release therapy of curcumin to treat gastric ulcers. The solid dispersions of curcumin with Eudragit® EPO were prepared by the solvent evaporation method at various ratios to improve the solubility and the dissolution of curcumin. The optimum weight ratio of 1:5 for curcumin to Eudragit® EPO was used to incorporate into the raft forming systems. The raft forming formulations were composed of curcumin-Eudragit® EPO solid dispersions, sodium alginate as a gelling polymer and calcium carbonate for generating divalent Ca(2+) ions and carbon dioxide to form a floating raft. All formulations formed a gelled raft in 1min and sustained buoyancy on the 0.1N hydrochloric acid (pH 1.2) surface with a 60-85% release of curcumin within 8h. The curative effect on the acetic acid-induced chronic gastric ulcer in rats was determined. The curcumin raft forming formulations at 40mg/kg once daily showed a superior curative effect on the gastric ulcer in terms of the ulcer index and healing index than the standard antisecretory agent: lansoprazole (1mg/kg, twice daily) and a curcumin suspension (40mg/kg, twice daily). These studies demonstrated that the new raft forming systems containing curcumin solid dispersions are promising carriers for a stomach-specific delivery of poorly soluble lipophilic compounds. Copyright © 2015 Elsevier B.V. All rights reserved.

Exfoliating and Dispersing Few-Layered Graphene in Low-Boiling-Point Organic Solvents towards Solution-Processed Optoelectronic Device Applications.

Science.gov (United States)

Zhang, Lu; Miao, Zhongshuo; Hao, Zhen; Liu, Jun

2016-05-06

With normal organic surfactants, graphene can only be dispersed in water and cannot be dispersed in low-boiling-point organic solvents, which hampers its application in solution-processed organic optoelectronic devices. Herein, we report the exfoliation of graphite into graphene in low-boiling-point organic solvents, for example, methanol and acetone, by using edge-carboxylated graphene quantum dots (ECGQD) as the surfactant. The great capability of ECGQD for graphene dispersion is due to its ultralarge π-conjugated unit that allows tight adhesion on the graphene surface through strong π-π interactions, its edge-carboxylated structure that diminishes the steric effects of the oxygen-containing functional groups on the basal plane of ECGQD, and its abundance of carboxylic acid groups for solubility. The graphene dispersion in methanol enables the application of graphene:ECGQD as a cathode interlayer in polymer solar cells (PSCs). Moreover, the PSC device performance of graphene:ECGQD is better than that of Ca, the state-of-the-art cathode interlayer material. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dispersants in an organic medium: synthesis and physicochemical study of dispersants for fuels and lubricants; Dispersants en milieu organique: synthese et etude physicochimique de dispersants pour carburants et lubrifiants

Energy Technology Data Exchange (ETDEWEB)

Dubois-Clochard, M.C.

1998-11-19

Carbonaceous deposits coming from the fuel and the lubricant are known to form over time at critical locations in an engine. In general, the deposits have an adverse effect on four functional areas which are the fuel metering system, the intake system, the lubrication system and the combustion chambers. These deposits can degrade vehicle performance and drive-ability, reduce fuel economy, increase fuel consumption and pollutant emissions and may lead to the destruction of the engine. In order to remedy these problems, detergent-dispersant additives are used in fuels and lubricants to avoid or decrease deposit adhesion on metallic surfaces and prevent from deposit aggregation. These products are mainly polymer surfactants and in this work, poly-iso-butenyl-succinimide of different structures have been studied. Firstly, 'comb like' polymers have been synthesized. Then they have been compared to classical di-bloc additives in terms of performance and action mechanism. These additives are adsorbed from their hydrophilic polyamine part on the acidic functions of the carbon black surface chosen as an engine deposit model and on the aluminium oxide function of an aluminium powder chosen as an engine wall model. The adsorption increases with temperature on the two solids. Their affinity with the solid surface increases with the length of the hydrophilic part. In the same way, changing the di-bloc structure for a comb like one lead to a better adsorption. At low concentration, it has been shown that the adsorption phenomenon was irreversible, due to the polymer structure of the polar part. Depending on the space required by the hydrophilic part on the solid surface, a more of less dense monolayer is formed. At higher concentrations, an important increase of the adsorbed amount appears. This phenomenon is totally reversible showing that the interactions additive / additive are weak. The dispersing efficiency of a comb like structure is better than a di-bloc one as

Dispersion Interactions between Urea and Nucleobases Contribute to the Destabilization of RNA by Urea in Aqueous Solution

Science.gov (United States)

Kasavajhala, Koushik; Bikkina, Swetha; Patil, Indrajit; MacKerell, Alexander D.; Priyakumar, U. Deva

2015-01-01

Urea has long been used to investigate protein folding and, more recently, RNA folding. Studies have proposed that urea denatures RNA by participating in stacking interactions and hydrogen bonds with nucleic acid bases. In this study, the ability of urea to form unconventional stacking interactions with RNA bases is investigated using ab initio calculations (RI-MP2 and CCSD(T) methods with the aug-cc-pVDZ basis set). A total of 29 stable nucleobase-urea stacked complexes are identified in which the intermolecular interaction energies (up to −14 kcal/mol) are dominated by dispersion effects. Natural bond orbital (NBO) and atoms in molecules (AIM) calculations further confirm strong interactions between urea and nucleobases. Calculations on model systems with multiple urea and water molecules interacting with a guanine base lead to a hypothesis that urea molecules along with water are able to form cage-like structures capable of trapping nucleic acid bases in extrahelical states by forming both hydrogen bonded and dispersion interactions, thereby contributing to the unfolding of RNA in the presence of urea in aqueous solution. PMID:25668757

Dispersion of coupled mode-gap cavities

NARCIS (Netherlands)

Lian, Jin; Sokolov, Sergei; Yuce, E.; Combrie, S.; de Rossi, A.; Mosk, Allard

2015-01-01

The dispersion of a coupled resonator optical waveguide made of photonic crystal mode-gap cavities is pronouncedly asymmetric. This asymmetry cannot be explained by the standard tight binding model. We show that the fundamental cause of the asymmetric dispersion is the inherent dispersive cavity

Discrete dispersion models and their Tweedie asymptotics

DEFF Research Database (Denmark)

Jørgensen, Bent; Kokonendji, Célestin C.

2016-01-01

The paper introduce a class of two-parameter discrete dispersion models, obtained by combining convolution with a factorial tilting operation, similar to exponential dispersion models which combine convolution and exponential tilting. The equidispersed Poisson model has a special place in this ap......The paper introduce a class of two-parameter discrete dispersion models, obtained by combining convolution with a factorial tilting operation, similar to exponential dispersion models which combine convolution and exponential tilting. The equidispersed Poisson model has a special place...... in this approach, whereas several overdispersed discrete distributions, such as the Neyman Type A, Pólya-Aeppli, negative binomial and Poisson-inverse Gaussian, turn out to be Poisson-Tweedie factorial dispersion models with power dispersion functions, analogous to ordinary Tweedie exponential dispersion models...... with power variance functions. Using the factorial cumulant generating function as tool, we introduce a dilation operation as a discrete analogue of scaling, generalizing binomial thinning. The Poisson-Tweedie factorial dispersion models are closed under dilation, which in turn leads to a Poisson...

Controlling Styrene Maleic Acid Lipid Particles through RAFT.

Science.gov (United States)

Smith, Anton A A; Autzen, Henriette E; Laursen, Tomas; Wu, Vincent; Yen, Max; Hall, Aaron; Hansen, Scott D; Cheng, Yifan; Xu, Ting

2017-11-13

The ability of styrene maleic acid copolymers to dissolve lipid membranes into nanosized lipid particles is a facile method of obtaining membrane proteins in solubilized lipid discs while conserving part of their native lipid environment. While the currently used copolymers can readily extract membrane proteins in native nanodiscs, their highly disperse composition is likely to influence the dispersity of the discs as well as the extraction efficiency. In this study, reversible addition-fragmentation chain transfer was used to control the polymer architecture and dispersity of molecular weights with a high-precision. Based on Monte Carlo simulations of the polymerizations, the monomer composition was predicted and allowed a structure-function analysis of the polymer architecture, in relation to their ability to assemble into lipid nanoparticles. We show that a higher degree of control of the polymer architecture generates more homogeneous samples. We hypothesize that low dispersity copolymers, with control of polymer architecture are an ideal framework for the rational design of polymers for customized isolation and characterization of integral membrane proteins in native lipid bilayer systems.

Determination of spirocyclic tetronic/tetramic acid derivatives and neonicotinoid insecticides in fruits and vegetables by liquid chromatography and mass spectrometry after dispersive liquid-liquid microextraction.

Science.gov (United States)

Pastor-Belda, Marta; Garrido, Isabel; Campillo, Natalia; Viñas, Pilar; Hellín, Pilar; Flores, Pilar; Fenoll, José

2016-07-01

Dispersive liquid-liquid microextraction was used to preconcentrate three spirocyclic tetronic/tetramic acid derivatives (spirotetramat, spiromesifen and spirodiclofen) and five neonicotinoid (thiamethoxam, chlotianidin, imidacloprid, acetamiprid and thiacloprid) insecticides previously extracted from fruit and vegetable matrices with acetonitrile. The organic enriched phase was evaporated, reconstituted in 25μL acetonitrile and analyzed by reversed-phase liquid chromatography with tandem mass spectrometry using a triple quadrupole in selected reaction monitoring mode. Enrichment factors in the 15-100 range were obtained. A matrix effect was observed, the detection limits varying between 0.025 and 0.5ngg(-1), depending on the compound and the sample matrix. The developed method was applied to the analysis of 25 samples corresponding to five different fruit and vegetable matrices. Only thiamethoxam was detected in a lemon sample at a concentration close to the quantification limit, and spiromesifen and spirotetramat at concentrations between 11.6 and 54.5ngg(-1). Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of Fatty acids and beeswax addition on properties of sodium caseinate dispersions and films.

Science.gov (United States)

Fabra, M J; Jiménez, A; Atarés, L; Talens, P; Chiralt, A

2009-06-08

Edible films based on sodium caseinate and different saturated fatty acids, oleic acid, or beeswax were formulated. Film-forming emulsions were characterized in terms of particle size distribution, rheological behavior and surface tension. In order to evaluate the influence of lipids on sodium caseinate matrices, mechanical, optical, and water vapor barrier properties were studied, taking into account the effect of water content and film structure on such properties. Saturated fatty acids affected the film properties in a particular way due to the formation of bilayer structures which limited water vapor permeability, giving rise to nonflexible and more opaque films. Oleic acid and beeswax were less effective as water vapor barriers, although the former imparted more flexibility to the caseinate films and did not reduce the film transparency notably.

Properties of Eco-friendly Acrylic Resin/Clay Nanocomposites Prepared by Non-aqueous Dispersion (NAD) Polymerization

Energy Technology Data Exchange (ETDEWEB)

Kim, Yeongho; Lee, Minho; Jeon, Hyeon Yeol; Min, Byong Hun; Kim, Jeong Ho [Univ. of Suwon, Hwaseong (Korea, Republic of); Lee, Young Chul [Korea Institute of Industrial Technology, Seoul (Korea, Republic of)

2016-02-15

Eco-friendly acrylic resin/clay nanocomposites containing pristine montmorillonite (PM) or modified clays (30B and 25A) were prepared from acrylic and styrenic monomers using non-aqueous dispersion (NAD) polymerization. Effect of nanoclays on physical properties of polymerization product and resulting nanocomposites was investigated. In view of NAD particle stability, addition of nanoclay at the beginning of polymerization is proved to be good. Results of gel fraction, acid value and viscosity of the NAD product showed that nanocomposites containing clay 25A showed better physical properties than the ones with other clays. GPC results exhibit the increase in molecular weight and decrease in polydispersity index for the 25A nanocomposite. Increase in layer distance confirmed from XRD analysis showed good dispersion of 25A in the nanocomposite. Thermal and dynamic mechanical analysis showed that highest glass transition temperature and storage modulus for 25A nanocomposites. These results indicate that 25A nanoclay gives the best properties in the process of non-aqueous dispersion polymerization of acrylic resin/nanoclay nanocomposites.

Properties of Eco-friendly Acrylic Resin/Clay Nanocomposites Prepared by Non-aqueous Dispersion (NAD) Polymerization

International Nuclear Information System (INIS)

Kim, Yeongho; Lee, Minho; Jeon, Hyeon Yeol; Min, Byong Hun; Kim, Jeong Ho; Lee, Young Chul

2016-01-01

Eco-friendly acrylic resin/clay nanocomposites containing pristine montmorillonite (PM) or modified clays (30B and 25A) were prepared from acrylic and styrenic monomers using non-aqueous dispersion (NAD) polymerization. Effect of nanoclays on physical properties of polymerization product and resulting nanocomposites was investigated. In view of NAD particle stability, addition of nanoclay at the beginning of polymerization is proved to be good. Results of gel fraction, acid value and viscosity of the NAD product showed that nanocomposites containing clay 25A showed better physical properties than the ones with other clays. GPC results exhibit the increase in molecular weight and decrease in polydispersity index for the 25A nanocomposite. Increase in layer distance confirmed from XRD analysis showed good dispersion of 25A in the nanocomposite. Thermal and dynamic mechanical analysis showed that highest glass transition temperature and storage modulus for 25A nanocomposites. These results indicate that 25A nanoclay gives the best properties in the process of non-aqueous dispersion polymerization of acrylic resin/nanoclay nanocomposites

Single-particle dispersion in compressible turbulence

Science.gov (United States)

Zhang, Qingqing; Xiao, Zuoli

2018-04-01

Single-particle dispersion statistics in compressible box turbulence are studied using direct numerical simulation. Focus is placed on the detailed discussion of effects of the particle Stokes number and turbulent Mach number, as well as the forcing type. When solenoidal forcing is adopted, it is found that the single-particle dispersion undergoes a transition from the ballistic regime at short times to the diffusive regime at long times, in agreement with Taylor's particle dispersion argument. The strongest dispersion of heavy particles is announced when the Stokes number is of order 1, which is similar to the scenario in incompressible turbulence. The dispersion tends to be suppressed as the Mach number increases. When hybrid solenoidal and compressive forcing at a ratio of 1/2 is employed, the flow field shows apparent anisotropic property, characterized by the appearance of large shock wave structures. Accordingly, the single-particle dispersion shows extremely different behavior from the solenoidal forcing case.

Direct generation of titanium dioxide nanoparticles dispersion under supercritical conditions for photocatalytic active thermoplastic surfaces for microbiological inactivation

Energy Technology Data Exchange (ETDEWEB)

Zydziak, Nicolas, E-mail: nicolas.zydziak@kit.edu [Polymer Engineering Department, Fraunhofer Institute of Chemical Technology, Joseph-von-Fraunhofer-Str. 7, 76327 Pfinztal (Germany); Zanin, Maria-Helena Ambrosio [Laboratory of Chemical Processes and Particle Technology Bionanomanufacturing, Institute for Technological Research of the State of São Paulo – IPT, Av. Prof. Almeida Prado 532, Cidade Universitária, CEP 05508-901 São Paulo, SP (Brazil); Trick, Iris [Environmental Biotechnology and Bioprocess Engineering Department, Fraunhofer Institute for Interfacial Engineering and Biotechnology, Nobelstrasse 12, 70569 Stuttgart (Germany); Hübner, Christof [Polymer Engineering Department, Fraunhofer Institute of Chemical Technology, Joseph-von-Fraunhofer-Str. 7, 76327 Pfinztal (Germany)

2015-03-01

Thermoplastic poly(propylene) (PP) and acrylonitrile-butadiene-styrene (ABS) surfaces were coated with silica based films via the sol–gel process, containing titanium dioxide (TiO{sub 2}) as photocatalyst. TiO{sub 2} was previously synthesized via sol–gel and treated under supercritical conditions in water dispersions. The characterization of the TiO{sub 2} dispersions was performed via disc centrifuge to determine the particle size and via Raman spectroscopy and X-Ray Diffraction (XRD) to characterize the crystallinity of TiO{sub 2}. The synthesized TiO{sub 2} dispersions and commercially available TiO{sub 2} particles were incorporated in silica based films which were synthesized under acidic or basic conditions, leading to dense or porous films respectively. The morphology of the films was characterized via Scanning Electron Microscopy (SEM). The incorporation of synthesized TiO{sub 2} in the coating led to photocatalytically more active thermoplastic surfaces than films formulated with commercially available TiO{sub 2} as determined via dye discoloration test. A microbiological test performed with Sarcina lutea confirmed this result and showed an inactivation factor of 6 (99.9999%) after 24 h UV irradiation, for synthesized TiO{sub 2} incorporated in acidic formulated silica layer on ABS surfaces. - Highlights: • We report about photocatalytic layers formulated on thermoplastic surfaces. • We synthesized silica layer and TiO{sub 2} via sol–gel and supercritical treatment. • Amorphous, crystalline and commercial dispersions were generated and characterized. • The morphology of dense and porous photocatalytic layers is observed via SEM. • Discoloration and microbiological tests correlate activity and surface morphology.

Demonstration of Lignin-to-Peroxidase Direct Electron Transfer: A TRANSIENT-STATE KINETICS, DIRECTED MUTAGENESIS, EPR, AND NMR STUDY.

Science.gov (United States)

Sáez-Jiménez, Verónica; Baratto, Maria Camilla; Pogni, Rebecca; Rencoret, Jorge; Gutiérrez, Ana; Santos, José Ignacio; Martínez, Angel T; Ruiz-Dueñas, Francisco Javier

2015-09-18

Versatile peroxidase (VP) is a high redox-potential peroxidase of biotechnological interest that is able to oxidize phenolic and non-phenolic aromatics, Mn(2+), and different dyes. The ability of VP from Pleurotus eryngii to oxidize water-soluble lignins (softwood and hardwood lignosulfonates) is demonstrated here by a combination of directed mutagenesis and spectroscopic techniques, among others. In addition, direct electron transfer between the peroxidase and the lignin macromolecule was kinetically characterized using stopped-flow spectrophotometry. VP variants were used to show that this reaction strongly depends on the presence of a solvent-exposed tryptophan residue (Trp-164). Moreover, the tryptophanyl radical detected by EPR spectroscopy of H2O2-activated VP (being absent from the W164S variant) was identified as catalytically active because it was reduced during lignosulfonate oxidation, resulting in the appearance of a lignin radical. The decrease of lignin fluorescence (excitation at 355 nm/emission at 400 nm) during VP treatment under steady-state conditions was accompanied by a decrease of the lignin (aromatic nuclei and side chains) signals in one-dimensional and two-dimensional NMR spectra, confirming the ligninolytic capabilities of the enzyme. Simultaneously, size-exclusion chromatography showed an increase of the molecular mass of the modified residual lignin, especially for the (low molecular mass) hardwood lignosulfonate, revealing that the oxidation products tend to recondense during the VP treatment. Finally, mutagenesis of selected residues neighboring Trp-164 resulted in improved apparent second-order rate constants for lignosulfonate reactions, revealing that changes in its protein environment (modifying the net negative charge and/or substrate accessibility/binding) can modulate the reactivity of the catalytic tryptophan. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Control of Biofilms with the Fatty Acid Signaling Molecule cis-2-Decenoic Acid

Directory of Open Access Journals (Sweden)

Cláudia N. H. Marques

2015-11-01

Full Text Available Biofilms are complex communities of microorganisms in organized structures attached to surfaces. Importantly, biofilms are a major cause of bacterial infections in humans, and remain one of the most significant challenges to modern medical practice. Unfortunately, conventional therapies have shown to be inadequate in the treatment of most chronic biofilm infections based on the extraordinary innate tolerance of biofilms to antibiotics. Antagonists of quorum sensing signaling molecules have been used as means to control biofilms. QS and other cell-cell communication molecules are able to revert biofilm tolerance, prevent biofilm formation and disrupt fully developed biofilms, albeit with restricted effectiveness. Recently however, it has been demonstrated that Pseudomonas aeruginosa produces a small messenger molecule cis-2-decenoic acid (cis-DA that shows significant promise as an effective adjunctive to antimicrobial treatment of biofilms. This molecule is responsible for induction of the native biofilm dispersion response in a range of Gram-negative and Gram-positive bacteria and in yeast, and has been shown to reverse persistence, increase microbial metabolic activity and significantly enhance the cidal effects of conventional antimicrobial agents. In this manuscript, the use of cis-2-decenoic acid as a novel agent for biofilm control is discussed. Stimulating the biofilm dispersion response as a novel antimicrobial strategy holds significant promise for enhanced treatment of infections and in the prevention of biofilm formation.

Nest-mediated seed dispersal

Science.gov (United States)

Robert J. Warren; Jason P. Love; Mark A. Bradford

2017-01-01

Many plant seeds travel on the wind and through animal ingestion or adhesion; however, an overlooked dispersal mode may lurk within those dispersal modes. Viable seeds may remain attached or embedded within materials birds gather for nest building. Our objective was to determine if birds inadvertently transport seeds when they forage for plant materials to...

Impact of primary amine group from aminophospholipids and amino acids on marine phospholipids stability: Non-enzymatic browning and lipid oxidation

DEFF Research Database (Denmark)

Lu, Henna Fung Sieng; Nielsen, Nina Skall; Baron, Caroline P.

2013-01-01

The main objective of this study was to investigate the oxidative stability and non-enzymatic browning reactions of marine PL in the presence or in the absence of primary amine group from aminophospholipids and amino acids. Marine phospholipids liposomal dispersions were prepared from two authentic......) Strecker derived volatiles, (ii) yellowness index (YI), (iii) hydrophobic and (iv) hydrophilic pyrroles content. The oxidative stability of the samples was assessed through measurement of secondary lipid derived volatile oxidation products. The result showed that the presence of PE and amino acids caused...... the formation of pyrroles, generated Strecker derived volatiles, decreased the YI development and lowered lipid oxidation. The lower degree of lipid oxidation in liposomal dispersions containing amino acids might be attributed to antioxidative properties of pyrroles or amino acids....

Atmospheric dispersion of radioactive materials

International Nuclear Information System (INIS)

Chino, Masamichi

1988-01-01

The report describes currently available techniques for predicting the dispersion of accidentally released radioactive materials and techniques for visualization using computer graphics. A simulation study is also made on the dispersion of radioactive materials released from the Chernobyl plant. The simplest models include the Gauss plume model and the puff model, which cannot serve to analyze the effects of the topography, vertical wind shear, temperature inversion layer, etc. Numerical analysis methods using advection and dispersion equations are widely adopted for detailed evaluation of dispersion in an emergency. An objective analysis model or a hydrodynamical model is often used to calculate the air currents which are required to determine the advection. A small system based on the puff model is widely adopted in Europe, where the topography is considered to have only simple effects. A more sophisticated large-sized system is required in nuclear facilities located in an area with more complex topographic features. An emergency system for dispersion calculation should be equipped with a graphic display to serve for quick understanding of the radioactivity distribution. (Nogami, K.)

Dispersant affects the cellular influences of single-wall carbon nanotube: the role of CNT as carrier of dispersants.

Science.gov (United States)

Horie, Masanori; Stowe, Mayumi; Tabei, Miki; Kato, Haruhisa; Nakamura, Ayako; Endoh, Shigehisa; Morimoto, Yasuo; Fujita, Katsuhide

2013-06-01

The application of carbon nanotube (CNT) as a functional material to engineering and life sciences is advanced. In order to evaluate the cytotoxicity of CNT in vitro, some chemical and biological reagents are used for dispersants. In the present study, the cellular influences of six kinds of chemical or biological reagents used as dispersants were examined. Pluronic F-127, Pluronic F-68, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), pulmonary surfactant preparation Surfacten®, bovine serum albumin (BSA) and Tween 80 were used in the preparation of CNT-medium dispersants. The influences of each reagent on cell viability in human lung carcinoma A549 cells were small. However, Pluronic F-127, DPPC, Surfacten® and Tween 80 induced an increase of intracellular reactive oxygen species (ROS) level. Next, CNT-medium dispersions were prepared, using each reagent as a dispersant and applied to A549 cells. The cellular influences depended on the kind of dispersant. Cells exposed to CNT dispersion including Pluronic® F-127, Surfacten®, DPPC and Tween 80 showed LDH release to the culture supernatant. Induction of intracellular ROS level was observed in cells exposed to CNT dispersion including each reagent except BSA. These results suggest that the adsorbed dispersant reagents on the surface of the CNT affect its cellular influences, particularly the induction of oxidative stress.

Stable dispersion of nanodiamonds in oil and their tribological properties as lubricant additives

Science.gov (United States)

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

2017-09-01

Nanodiamonds (NDs) are innovative additives when a combination of mechanical, thermal, tribological, and dielectric properties are required. In this study, a surface modification with oleic acid (OA) is developed for the deaggregation and prolonged dispersion of NDs in oil, and the effect of the NDs as lubricant additives on the tribological properties of a steel substrate is investigated. The OA renders the ND surface hydrophobic and decreases the average particle size from 268.6 to 20.1 nm. The OA-treated NDs exhibit very stable dispersion in oil even after more than 10 days, compared with the untreated NDs. From the analyses of the friction coefficient, wear loss, and worn surfaces using a ball-on-disk wear test, it is concluded that a 0.05 wt% addition of OA-treated NDs in oil lubricant provides excellent friction and anti-wear properties with the friction coefficient being reduced by 23%.

Nanocomposites of phosphonic-acid-functionalized polyethylenes with inorganic quantum dots.

Science.gov (United States)

Rünzi, Thomas; Baier, Moritz C; Negele, Carla; Krumova, Marina; Mecking, Stefan

2015-01-01

Insertion of diethyl vinyl phosphonates and free vinyl phosphonic acid, respectively, into [(P^O)Pd(Me)(dmso)] ((P^O) = κ(2)-P,O-Ar2PC6H4SO2O with Ar = 2-MeOC6H4) (1-dmso) occurs in a 2,1- as well as 1,2-fashion, to form a four-and a five-membered chelate [(P^O)Pd{κ(2)-C,O-CH(P(O)(OR)2)CH2CH3}] and [(P^O)Pd{κ(2)-C,O-CH2CH(P(O)(OR)2)CH3}] (R = H, Et). No decomposition or other reactions of 1 by free phosphonic acid moieties occur. Copolymerization in a pressure reactor by 1-dmso yields linear random poly(ethylene-co-diethyl vinyl phosphonate) and poly(ethylene-co-vinyl phosphonic acid). In these copolymerizations, reversible coordination of the phosphonate moieties of free monomer as well as chelate formation by incorporated monomer retards chain growth as also evidenced by relative binding studies of diethyl phosphonate towards 1. Post-polymerization emulsification of poly(ethylene-co-vinyl phosphonic acid) together with CdSe/CdS quantum dots (QDs) yields submicron (ca. 50 nm from dynamic light scattering (DLS) and transmission electron microscopy (TEM)) polymer particles with the QDs embedded in the functionalized polyethylene in a nonaggregated fashion. This embedding benefits the fluorescence behavior in terms of continuous emission and life-time as revealed by wide-field fluorescence measurements. These composite particle dispersions are employed as a ″masterbatch" together with an aqueous high density polyethylene (HDPE) dispersion to generate thin films (by spin-coating) and bulk materials (from the melt), respectively, in which the inorganic nanoparticles remain highly disperse. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of a highly dispersed CuO catalyst on CoAl-HT for the epoxidation of styrene.

Science.gov (United States)

Hu, Rui; Yang, Pengfei; Pan, Yongning; Li, Yunpeng; He, Yufei; Feng, Junting; Li, Dianqing

2017-10-10

A highly dispersed CuO catalyst was prepared by the deposition-precipitation method and evaluated for the catalytic epoxidation of styrene with tert-butyl hydroperoxide (TBHP) as the oxidant under solvent acetonitrile conditions. Compared with MgAl hydrotalcite (MgAl-HT)-, MgO-, TiO 2 -, C-, and MCM-22-supported catalysts, CuO/CoAl-HT exhibited preferable activity and selectivity towards styrene oxide (72% selectivity at 99.5% styrene conversion) due to its high dispersion of CuO and surface area of Cu. The improved dispersion of CuO/CoAl-HT could be ascribed to the nature of HT support, especially the synergistic effect of acidic and basic sites on the surface, which facilitated the formation of highly dispersed CuO species. A structure-performance relationship study indicated that copper(ii) in CuO was the active site for the epoxidation and oxidation of styrene, and that Cu II of rich electronic density favored the improvement of selectivity of styrene oxide. Based on these results, a reaction mechanism was proposed. Moreover, the preferred catalytic performance of CuO/CoAl-HT could be maintained in five reused cycles.

Lignin-based membranes for electrolyte transference

Energy Technology Data Exchange (ETDEWEB)

Zhang, Xiao; Garcia-Valls, Ricard [Departament d' Enginyeria Quimica, Escola Tecnica Superior d' Enginyeria Quimica, Universitat Rovira i Virgili, Av. Paisos Catalans 26, 43007 Tarragona (Spain); Benavente, Juana [Department of Applied Fisics, Faculty of Science, University of Malaga, Malaga (Spain)

2005-08-18

Homogeneous PSf-LS membranes are formed by incorporating Lignosulfonate (LS) into the Polysulfone (PSf) network. LS obtained from sulfite pulping process contains sulfonic acid groups that will act as proton transport media. PSf-LS membranes were characterized by reflectance Infrared and scanning electron microscopy. LS showed significant influence on membrane morphology. Higher LS concentration caused a decrease in macrovoid formation and induced larger pores. Precipitation temperature was investigated as influencing parameter. Proton fluxes through PSf-LS membranes were measured by transport experiments. Impedance analysis confirmed that PSf-LS membranes possess ion conductivity. The selected PSf-LS membranes exhibited high selectivity for proton over methanol, which indicates their potential applicability in direct methanol fuel cell (DMFC). (author)

Synthesis and antibacterial activity of water-dispersible silver nanoparticles via micellar nanoreactors

Science.gov (United States)

Pofali, Prasad; Shirolikar, Seema; Borde, Lalit; Pattani, Aditya; Dandekar, Prajakta; Jain, Ratnesh

2018-04-01

We have synthesized silver nanoparticles (AgNPs) using micelles of sugar fatty acid ester by dissolving the surfactant in a mixture of iso-octane and n-butanol, with solid-liquid extraction. Highly concentrated, water-dispersible AgNPs were obtained after thorough washing with alcohol, to remove excess of sucrose fatty acid ester DK SS and salt, followed by drying. The particles were characterized for their size, morphology and crystallinity using UV-Visible spectrophotometry, Transmission Electron Microscopy and x-ray diffractometry. Antibacterial study, confirmed the activity of nanoparticles against E. coli, P. aeruginosa and S. aureus, which causes diseases including diarrhoea and several life-threatening infections. Antibacterial activity of E. coli and P. aeruginosa was found to be 2.5 fold and for S. aureus 1.6 fold compared to 50 ppm conc. of Silver Nitrate. Our method of producing nanoparticles is employed as a platform technology for synthesizing other inorganic nanoparticles. This is the first report discussing the use of micellar carriers for obtaining silver nanopowder, to the best of our knowledge, which has the potential to overcome limitations during fabrication of AgNPs using reverse/inverse micelles. Our method yielded nano-sized, water-dispersible AgNPs via an easy and economic approach. The one-pot approach possesses advantages in terms of cost and simplicity, as compared with traditional methods of producing powdered AgNPs using energy intensive and expensive techniques like lyophilisation. The developed method, thus, possesses immense potential for commercial synthesis of AgNPs.

Effectiveness of dispersants on thick oil slicks

International Nuclear Information System (INIS)

Ross, S.; Belore, R.

1993-01-01

Experiments were conducted to determine the relationship between dispersant effectiveness and oil slick thickness, and thereby determine the optimum time for applying dispersant onto spilled oil at sea. Tests were completed at a lab-scale level by varying the three parameters of oil type, dispersant application, and oil thickness. The tests were intended to be comparative only. The primary oils used were Alberta sweet mix blend and Hibernia B-27 crude. The dispersant, Corexit 9527, was applied either premixed with the oil, dropwise in one application, or dropwise in multiple applications to simulate a multi-hit aircraft operation. The apparatus used in the experiment was an oscillating hoop tank, with oil-containing rings used to obtain and maintain uniform slick thickness. The results indicate that the effectiveness potential of a chemical dispersant does not decrease as slick thickness increases. In fact, results of the tests involving Hibernia oil suggest that oils that tend to herd easily would be treated more effectively if dispersant were applied when the oil was relatively thick (1 mm or greater) to avoid herding problems. The oil slicks premixed with dispersant did not disperse well in the thick oil tests, not because of dispersant-oil interaction problems but because of reduced mixing energy. 6 refs., 4 figs., 1 tab

Dispersal Timing: Emigration of Insects Living in Patchy Environments.

Directory of Open Access Journals (Sweden)

Milica Lakovic

Full Text Available Dispersal is a life-history trait affecting dynamics and persistence of populations; it evolves under various known selective pressures. Theoretical studies on dispersal typically assume 'natal dispersal', where individuals emigrate right after birth. But emigration may also occur during a later moment within a reproductive season ('breeding dispersal'. For example, some female butterflies first deposit eggs in their natal patch before migrating to other site(s to continue egg-laying there. How breeding compared to natal dispersal influences the evolution of dispersal has not been explored. To close this gap we used an individual-based simulation approach to analyze (i the evolution of timing of breeding dispersal in annual organisms, (ii its influence on dispersal (compared to natal dispersal. Furthermore, we tested (iii its performance in direct evolutionary contest with individuals following a natal dispersal strategy. Our results show that evolution should typically result in lower dispersal under breeding dispersal, especially when costs of dispersal are low and population size is small. By distributing offspring evenly across two patches, breeding dispersal allows reducing direct sibling competition in the next generation whereas natal dispersal can only reduce trans-generational kin competition by producing highly dispersive offspring in each generation. The added benefit of breeding dispersal is most prominent in patches with small population sizes. Finally, the evolutionary contests show that a breeding dispersal strategy would universally out-compete natal dispersal.

Partitioning of fresh crude oil between floating, dispersed and sediment phases: Effect of exposure order to dispersant and granular materials.

Science.gov (United States)

Boglaienko, Daria; Tansel, Berrin

2016-06-15

When three or more high and low energy substrates are mixed, wetting order can significantly affect the behavior of the mixture. We analyzed the phase distribution of fresh floating Louisiana crude oil into dispersed, settled and floating phases depending on the exposure sequence to Corexit 9500A (dispersant) and granular materials. In the experiments artificial sea water at salinity 34‰ was used. Limestone (2.00-0.300 mm) and quartz sand (0.300-0.075 mm) were used as the natural granular materials. Dispersant Corexit 9500A increased the amount of dispersed oil up to 33.76 ± 7.04%. Addition of granular materials after the dispersant increased dispersion of oil to 47.96 ± 1.96%. When solid particles were applied on the floating oil before the dispersant, oil was captured as oil-particle aggregates and removed from the floating layer. However, dispersant addition led to partial release of the captured oil, removing it from the aggregated form to the dispersed and floating phases. There was no visible oil aggregation with the granular materials when quartz or limestone was at the bottom of the flask before the addition of oil and dispersant. The results show that granular materials can be effective when applied from the surface for aggregating or dispersing oil. However, the granular materials in the sediments are not effective neither for aggregating nor dispersing floating oil. Copyright © 2016 Elsevier Ltd. All rights reserved.

Solitonic Dispersive Hydrodynamics: Theory and Observation

Science.gov (United States)

Maiden, Michelle D.; Anderson, Dalton V.; Franco, Nevil A.; El, Gennady A.; Hoefer, Mark A.

2018-04-01

Ubiquitous nonlinear waves in dispersive media include localized solitons and extended hydrodynamic states such as dispersive shock waves. Despite their physical prominence and the development of thorough theoretical and experimental investigations of each separately, experiments and a unified theory of solitons and dispersive hydrodynamics are lacking. Here, a general soliton-mean field theory is introduced and used to describe the propagation of solitons in macroscopic hydrodynamic flows. Two universal adiabatic invariants of motion are identified that predict trapping or transmission of solitons by hydrodynamic states. The result of solitons incident upon smooth expansion waves or compressive, rapidly oscillating dispersive shock waves is the same, an effect termed hydrodynamic reciprocity. Experiments on viscous fluid conduits quantitatively confirm the soliton-mean field theory with broader implications for nonlinear optics, superfluids, geophysical fluids, and other dispersive hydrodynamic media.

Measuring short distance dispersal of Alliaria petiolata and determining potential long distance dispersal mechanisms

Directory of Open Access Journals (Sweden)

Christopher A. Loebach

2018-03-01

Full Text Available Introduction Alliaria petiolata, an herbaceous plant, has invaded woodlands in North America. Its ecology has been thoroughly studied, but an overlooked aspect of its biology is seed dispersal distances and mechanisms. We measured seed dispersal distances in the field and tested if epizoochory is a potential mechanism for long-distance seed dispersal. Methods Dispersal distances were measured by placing seed traps in a sector design around three seed point sources, which consisted of 15 second-year plants transplanted within a 0.25 m radius circle. Traps were placed at intervals ranging from 0.25–3.25 m from the point source. Traps remained in the field until a majority of seeds were dispersed. Eight probability density functions were fitted to seed trap counts via maximum likelihood. Epizoochory was tested as a potential seed dispersal mechanism for A. petiolata through a combination of field and laboratory experiments. To test if small mammals transport A. petiolata seeds in their fur, experimental blocks were placed around dense A. petiolata patches. Each block contained a mammal inclusion treatment (MIT and control. The MIT consisted of a wood-frame (31 × 61× 31 cm covered in wire mesh, except for the two 31 × 31 cm ends, placed over a germination tray filled with potting soil. A pan filled with bait was placed in the center of the tray. The control frame (11 × 31 × 61 cm was placed over a germination tray and completely covered in wire mesh to exclude animal activity. Treatments were in the field for peak seed dispersal. In March, trays were moved to a greenhouse and A. petiolata seedlings were counted and then compared between treatments. To determine if A. petiolata seeds attach to raccoon (Procyon lotor and white-tailed deer (Odocoileus virginianus fur, wet and dry seeds were dropped onto wet and dry fur. Furs were rotated 180 degrees and the seeds that remained attached were counted. To measure seed retention, seeds

Fundamentals of energy dispersive X-ray analysis

CERN Document Server

Russ, John C; Kiessling, R; Charles, J

1984-01-01

Fundamentals of Energy Dispersive X-ray Analysis provides an introduction to the fundamental principles of dispersive X-ray analysis. It presents descriptions, equations, and graphs to enable the users of these techniques to develop an intuitive and conceptual image of the physical processes involved in the generation and detection of X-rays. The book begins with a discussion of X-ray detection and measurement, which is accomplished by one of two types of X-ray spectrometer: energy dispersive or wavelength dispersive. The emphasis is on energy dispersive spectrometers, given their rather wid

EDF plan for a dispersant injection trial

International Nuclear Information System (INIS)

Mercier, Stephane; Corredera, Geraldine; Alves-Vieira, Maria; Mansour, Carine; You, Dominique

2012-09-01

In its strategy for SG fouling control, EDF is considering the use of dispersant as a preventive remedy. A trial on Golfech 2 started in May 2012. The dispersant selected for the trial is Polyacrylic Acid (PAA). The main goals of the test are to check and quantify the gain on iron transport to blowdown, to evaluate the possible effects on secondary side chemistry and the operational costs of the injection - reactant, ion exchange resins and filters. The results of the test, if satisfying, will be used to set EDF strategy for dispersant long term use on its fleet. So, one concern about the trial is to make sure that the conclusions of this test will be applicable to a wide range of EDF plants. For that purpose, several criteria have been examined for the choice of the candidate plant such as fouling level, secondary circuit materials (presence or absence of copper alloys,...), SG tube material, thermal power margin, secondary side chemistry (amine used and pH applied). Before starting the trial, EDF had to take into account the international feedback and to adapt it to its specific requirements: the neutralization amine was switched from ETA to morpholine, additional work had been completed to validate the innocuousness of PAA injection for EDF plants... This work especially includes laboratory testing of secondary side corrosion cracking in the presence of PAA and water chemistries used in EdF plants. Moreover, investigation on the thermal stability of PAA and degradation products was completed and further evaluation of environmental impact was performed. A dedicated skid for the injection of PAA was implemented in Golfech Chemicals injection room. The installation and the process were notably designed to take into account the high viscosity of the commercial product, and the need to proceed to a good rinsing of the pipes without increasing the discharged effluents. The first available data from Golfech 2 trial are also provided and discussed. (authors)

Frictional response of fatty acids on steel.

Science.gov (United States)

Sahoo, Rashmi R; Biswas, S K

2009-05-15

Self-assembled monolayers of fatty acids were formed on stainless steel by room-temperature solution deposition. The acids are covalently bound to the surface as carboxylate in a bidentate manner. To explore the effect of saturation in the carbon backbone on friction in sliding tribology, we study the response of saturated stearic acid (SA) and unsaturated linoleic acid (LA) as self-assembled monolayers using lateral force microscopy and nanotribometry and when the molecules are dispersed in hexadecane, using pin-on-disc tribometry. Over a very wide range (10 MPa-2.5 GPa) of contact pressures it is consistently demonstrated that the unsaturated linoleic acid molecules yield friction which is significantly lower than that of the saturated stearic acid. It is argued, using density functional theory predictions and XPS of slid track, that when the molecular backbone of unsaturated fatty acids are tilted and pressed strongly by a probe, in tribological contact, the high charge density of the double bond region of the backbone allows coupling with the steel substrate. The interaction yields a low friction carboxylate soap film on the substrate. The saturated fatty acid does not show this effect.

Dispersed-phase catalysis in coal liquefaction

International Nuclear Information System (INIS)

Utz, B.R.; Cugini, A.V.; Frommell, E.A.

1990-01-01

This paper reports that the specific reaction (activation) conditions for the conversion of catalyst precursors to unsupported catalyst have a direct effect on the catalytic activity and dispersion. The importance of reaction intermediates in decomposition of ammonium heptamolybdate and ammonium tetrathiomolybdate, and the sensitivity of these intermediates to reaction conditions, were studied in coal liquefaction systems. Recent results indicate that optimization of activation conditions facilitates the formation of a highly dispersed and active form of molybdenum disulfide for coal liquefaction. The use of the catalyst precursors ammonium heptamolybdate, ammonium tetrathiomolybdate, and molybdenum trisulfide for the conversion of coal to soluble products will be discussed. The use of an unsupported dispersed-phase catalyst for direct coal liquefaction is not a novel concept and has been employed in may studies with varying success. Dispersed-phase catalysts soluble and oil-soluble salts, and as finely divided powders. While some methods of catalyst introduction give higher dispersion of the catalyst and greater activity for the liquefaction of coal, all of the techniques allow the formation of a finely dispersed inorganic phase

Magnon dispersion in thin magnetic films

International Nuclear Information System (INIS)

Balashov, T; Wulfhekel, W; Buczek, P; Sandratskii, L; Ernst, A

2014-01-01

Although the dispersion of magnons has been measured in many bulk materials, few studies deal with the changes in the dispersion when the material is in the form of a thin film, a system that is of interest for applications. Here we review inelastic tunneling spectroscopy studies of magnon dispersion in Mn/Cu 3 Au(1 0 0) and present new studies on Co and Ni thin films on Cu(1 0 0). The dispersion in Mn and Co films closely follows the dispersion of bulk samples with negligible dependence on thickness. The lifetime of magnons depends slightly on film thickness, and decreases considerably as the magnon energy increases. In Ni/Cu(1 0 0) films the thickness dependence of dispersion is much more pronounced. The measurements indicate a considerable mode softening for thinner films. Magnon lifetimes decrease dramatically near the edge of the Brillouin zone due to a close proximity of the Stoner continuum. The experimental study is supported by first-principles calculations. (paper)

Magnon dispersion in thin magnetic films.

Science.gov (United States)

Balashov, T; Buczek, P; Sandratskii, L; Ernst, A; Wulfhekel, W

2014-10-01

Although the dispersion of magnons has been measured in many bulk materials, few studies deal with the changes in the dispersion when the material is in the form of a thin film, a system that is of interest for applications. Here we review inelastic tunneling spectroscopy studies of magnon dispersion in Mn/Cu3Au(1 0 0) and present new studies on Co and Ni thin films on Cu(1 0 0). The dispersion in Mn and Co films closely follows the dispersion of bulk samples with negligible dependence on thickness. The lifetime of magnons depends slightly on film thickness, and decreases considerably as the magnon energy increases. In Ni/Cu(1 0 0) films the thickness dependence of dispersion is much more pronounced. The measurements indicate a considerable mode softening for thinner films. Magnon lifetimes decrease dramatically near the edge of the Brillouin zone due to a close proximity of the Stoner continuum. The experimental study is supported by first-principles calculations.

Generalized dispersive wave emission in nonlinear fiber optics.

Science.gov (United States)

Webb, K E; Xu, Y Q; Erkintalo, M; Murdoch, S G

2013-01-15

We show that the emission of dispersive waves in nonlinear fiber optics is not limited to soliton-like pulses propagating in the anomalous dispersion regime. We demonstrate, both numerically and experimentally, that pulses propagating in the normal dispersion regime can excite resonant dispersive radiation across the zero-dispersion wavelength into the anomalous regime.

Dispersion Decay and Scattering Theory

CERN Document Server

Komech, Alexander

2012-01-01

A simplified, yet rigorous treatment of scattering theory methods and their applications Dispersion Decay and Scattering Theory provides thorough, easy-to-understand guidance on the application of scattering theory methods to modern problems in mathematics, quantum physics, and mathematical physics. Introducing spectral methods with applications to dispersion time-decay and scattering theory, this book presents, for the first time, the Agmon-Jensen-Kato spectral theory for the Schr?dinger equation, extending the theory to the Klein-Gordon equation. The dispersion decay plays a crucial role i

Variation of emulsion stability in sulfuric acid alkylation of isobutane with olefins

Energy Technology Data Exchange (ETDEWEB)

Sumanov, V.T.; Ovsyannikov, V.P.

1982-09-01

The makeup of the emulsion and its stability are determined to a great degree by the surface and viscosity properties of the acid. Investigates the dependence of emulsion stability on the properties of the acid circulating in the reactor section of an alkylation unit. Finds that as the surface-active substances that accumulate in the acid tend to lower its surface tension, and this in turn tends to disperse the hydrocarbon feedstock in the acid phase and forms a stable emulsion in the vigorously stirred reactor. Points out that as the acid viscosity increases, the segregation of microdrops of hydrocarbons from the acid phase becomes slower in the settling of the emulsion under natural conditions.

Effect of Additives and Fuel Blending on Emissions and Ash-Related Problems from Small-Scale Combustion of Reed Canary Grass

Directory of Open Access Journals (Sweden)

Sébastien Fournel

2015-07-01

Full Text Available Agricultural producers are interested in using biomass available on farms to substitute fossil fuels for heat production. However, energy crops like reed canary grass contain high nitrogen (N, sulfur (S, potassium (K and other ash-forming elements which lead to increased emissions of gases and particulate matter (PM and ash-related operational problems (e.g., melting during combustion. To address these problematic behaviors, reed canary grass was blended with wood (50 wt% and fuel additives (3 wt% such as aluminum silicates (sewage sludge, calcium (limestone and sulfur (lignosulfonate based additives. When burned in a top-feed pellet boiler (29 kW, the four blends resulted in a 17%–29% decrease of PM concentrations compared to pure reed canary grass probably because of a reduction of K release to flue gas. Nitrogen oxides (NOx and sulfur dioxide (SO2 emissions varied according to fuel N and S contents. This explains the lower NOx and SO2 levels obtained with wood based products and the higher SO2 generation with the grass/lignosulfonate blend. The proportion of clinkers found in combustion ash was greatly lessened (27%–98% with the use of additives, except for lignosulfonate. The positive effects of some additives may allow agricultural fuels to become viable alternatives.

Improved new generation dispersants

International Nuclear Information System (INIS)

Anon.

1993-01-01

The use of dispersants to combat oil spills has attracted controversy over the years, and there has been a number of accusations of the chemicals involved doing more harm than good. A new study by the International Petroleum Industry Environmental Conservation Association discusses the positive and the negatives of dispersant use to be considered when drawing up spill contingency plans. (author)

Dispersal of forest insects

Science.gov (United States)

Mcmanus, M. L.

1979-01-01

Dispersal flights of selected species of forest insects which are associated with periodic outbreaks of pests that occur over large contiguous forested areas are discussed. Gypsy moths, spruce budworms, and forest tent caterpillars were studied for their massive migrations in forested areas. Results indicate that large dispersals into forested areas are due to the females, except in the case of the gypsy moth.

Interspecific nematode signals regulate dispersal behavior.

Directory of Open Access Journals (Sweden)

Fatma Kaplan

Full Text Available Dispersal is an important nematode behavior. Upon crowding or food depletion, the free living bacteriovorus nematode Caenorhabditis elegans produces stress resistant dispersal larvae, called dauer, which are analogous to second stage juveniles (J2 of plant parasitic Meloidogyne spp. and infective juveniles (IJs of entomopathogenic nematodes (EPN, e.g., Steinernema feltiae. Regulation of dispersal behavior has not been thoroughly investigated for C. elegans or any other nematode species. Based on the fact that ascarosides regulate entry in dauer stage as well as multiple behaviors in C. elegans adults including mating, avoidance and aggregation, we hypothesized that ascarosides might also be involved in regulation of dispersal behavior in C. elegans and for other nematodes such as IJ of phylogenetically related EPNs.Liquid chromatography-mass spectrometry analysis of C. elegans dauer conditioned media, which shows strong dispersing activity, revealed four known ascarosides (ascr#2, ascr#3, ascr#8, icas#9. A synthetic blend of these ascarosides at physiologically relevant concentrations dispersed C. elegans dauer in the presence of food and also caused dispersion of IJs of S. feltiae and J2s of plant parasitic Meloidogyne spp. Assay guided fractionation revealed structural analogs as major active components of the S. feltiae (ascr#9 and C. elegans (ascr#2 dispersal blends. Further analysis revealed ascr#9 in all Steinernema spp. and Heterorhabditis spp. infected insect host cadavers.Ascaroside blends represent evolutionarily conserved, fundamentally important communication systems for nematodes from diverse habitats, and thus may provide sustainable means for control of parasitic nematodes.

Dispersal of Engineered Male Aedes aegypti Mosquitoes.

Science.gov (United States)

Winskill, Peter; Carvalho, Danilo O; Capurro, Margareth L; Alphey, Luke; Donnelly, Christl A; McKemey, Andrew R

2015-11-01

Aedes aegypti, the principal vector of dengue fever, have been genetically engineered for use in a sterile insect control programme. To improve our understanding of the dispersal ecology of mosquitoes and to inform appropriate release strategies of 'genetically sterile' male Aedes aegypti detailed knowledge of the dispersal ability of the released insects is needed. The dispersal ability of released 'genetically sterile' male Aedes aegypti at a field site in Brazil has been estimated. Dispersal kernels embedded within a generalized linear model framework were used to analyse data collected from three large scale mark release recapture studies. The methodology has been applied to previously published dispersal data to compare the dispersal ability of 'genetically sterile' male Aedes aegypti in contrasting environments. We parameterised dispersal kernels and estimated the mean distance travelled for insects in Brazil: 52.8 m (95% CI: 49.9 m, 56.8 m) and Malaysia: 58.0 m (95% CI: 51.1 m, 71.0 m). Our results provide specific, detailed estimates of the dispersal characteristics of released 'genetically sterile' male Aedes aegypti in the field. The comparative analysis indicates that despite differing environments and recapture rates, key features of the insects' dispersal kernels are conserved across the two studies. The results can be used to inform both risk assessments and release programmes using 'genetically sterile' male Aedes aegypti.

Direct monophasic replacement of fatty acid by DMSA on SPION surface

Energy Technology Data Exchange (ETDEWEB)

Gogoi, M. [Department of Physics, Tezpur University (Central University), Tezpur 784028 (India); Deb, P., E-mail: pdeb@tezu.ernet.in [Department of Physics, Tezpur University (Central University), Tezpur 784028 (India); Interface Chemistry and Surface Engineering, Max-Planck-Institut fuer Eisenforschung GmbH, Max-Planck-Strasse 1, 40237 Duesseldorf (Germany); Vasan, G.; Keil, P.; Kostka, A.; Erbe, A. [Interface Chemistry and Surface Engineering, Max-Planck-Institut fuer Eisenforschung GmbH, Max-Planck-Strasse 1, 40237 Duesseldorf (Germany)

2012-10-01

Highlights: Black-Right-Pointing-Pointer Monophasic replacement of fatty acid coating. Black-Right-Pointing-Pointer Ultrastable dispersion of hydrophilic SPION in a wide pH range. Black-Right-Pointing-Pointer Unaltered microstructure and property on surface modification. - Abstract: Tailoring the surface and understanding the surface characteristics is necessary for biomedical applications of superparamagnetic nanoparticles. In this paper, superparamagnetic iron oxide nanoparticles (SPIONs) were prepared by thermal decomposition of iron nitrate in presence of stearic acid as surfactant. Due to the multilayer organization of surfactant molecules over the nanoparticle surface, the surface potential can be tuned by pH changes and hence the nanoparticles can be made dispersible in nonpolar as well as in polar solvents. We have presented a simple, facile procedure for controlled replacement of stearic acid from maghemite surface and subsequent derivatization by biocompatible dimercaptosuccinic acid (DMSA) to obtain ultrastable hydrophilic nanoparticles with unaltered morphology, phase and properties. The surface chemistry of the functionalized SPIONs was analyzed by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) revealing the presence of bound and unbound thiol groups and disulfides, leading to its prolonged stability in aqueous medium. The consequence of spatially selective functionalization on the stability and solubility of surface hydrophilic SPION has also been realized.

Dispersant effectiveness: Studies into the causes of effectiveness variations

International Nuclear Information System (INIS)

Fingas, M.F.; Kyle, D.; Tennyson, E.

1995-01-01

Effectiveness, a key issue of using dispersants, is affected by many interrelated factors. The principal factors involved are the oil composition, dispersant formulation, sea surface turbulence and dispersant quantity. Oil composition is a very strong determinant. Current dispersant formulation effectiveness correlates strongly with the amount of saturate component in the oil. The other components of the oil, the asphaltenes, resins or polars and aromatic fractions show a negative correlation with the dispersant effectiveness. Viscosity is also a predictor of dispersant effectiveness and may have an effect because it is in turn determined by oil composition. Dispersant composition is significant and interacts with oil composition. Dispersants show high effectiveness at HLB values near 10. Sea turbulence strongly affects dispersant effectiveness.Effectiveness rises with increasing turbulence to a maximum value. Effectiveness for current commercial dispersants is gaussian around a peak salinity value. Peak effectiveness is achieved at very high dispersant quantities--at a ratio of 1:5, dispersant-to-oil volume. Dispersant effectiveness for those oils tested and under the conditions measured, is approximately logarithmic with dispersant quantity and will reach about 50% of its peak value at a dispersant to oil ratio of about 1:20 and near zero at a ratio of about 1:50

Dispersion properties of photonic crystal fibres

DEFF Research Database (Denmark)

Bjarklev, Anders Overgaard; Broeng, Jes; Dridi, Kim

1998-01-01

Approximate dispersion and bending properties of all-silica two-dimensional photonic crystal fibres are characterised by the combination of an effective-index model and classical analysis tools for optical fibres. We believe for the first time to have predicted the dispersion properties of photonic...... crystal fibres. The results strongly indicate that these fibres have potential applications as dispersion managing components...

Dispersion-engineered and highly-nonlinear microstructured polymer optical fibres

DEFF Research Database (Denmark)

Frosz, Michael Henoch; Nielsen, Kristian; Hlubina, Petr

2009-01-01

We demonstrate dispersion-engineering of microstructured polymer optical fibres (mPOFs) made of poly(methyl methacrylate) (PMMA). A significant shift of the total dispersion from the material dispersion is confirmed through measurement of the mPOF dispersion using white-light spectral interferome......We demonstrate dispersion-engineering of microstructured polymer optical fibres (mPOFs) made of poly(methyl methacrylate) (PMMA). A significant shift of the total dispersion from the material dispersion is confirmed through measurement of the mPOF dispersion using white-light spectral...

Indium sulfide precipitation from hydrochloric acid solutions of calcium and sodium chlorides

International Nuclear Information System (INIS)

Kochetkova, N.V.; Bayandina, Yu.E.; Toptygina, G.M.; Shepot'ko, A.O.

1988-01-01

The effect of precipitation duration, acid concentration, indium complexing with chloride ions on the process of indium sulfide chemical precipitation in hydrochloric acid solutions, precipitate composition and dispersity are studied. It is established that indium sulfide solubility increases in solutions with acid concentration exceeding 0.40-0.45 mol/l. Calcium and indium chloride addition to diluted hydrochloric solutions greatly increases the solubility of indium sulfide. The effect of calcium chloride on In 2 S 3 solubility is higher than that of sodium chloride

Synthesis and antibacterial evaluation of calcinated Ag-doped nano-hydroxyapatite with dispersibility.

Science.gov (United States)

Furuzono, Tsutomu; Motaharul, Mazumder; Kogai, Yasumichi; Azuma, Yoshinao; Sawa, Yoshiki

2015-05-01

Dispersible hydroxyapatite (HAp) nanoparticles are very useful for applying a monolayer to implantable medical devices using the nano-coating technique. To improve tolerance to infection on implanted medical devices, silver-doped HAp (Ag-HAp) nanoparticles with dispersiblity and crystallinity were synthesized, avoiding calcination-induced sintering, and evaluated for antibacterial activity. The Ca10-xAgx(PO4)6(OH)2 with x = 0 and 0.2 were prepared by wet chemical processing at 100°C. Before calcination at 700°C for 2 h, two kinds of anti-sintering agents, namely a Ca(NO3)2 (Ca salt) and a polyacrylic acid/Ca salt mixture (PAA-Ca), were used. Escherichia coli was used to evaluate the antibacterial activity of the nanopowder. When PAA-Ca was used as an anti-sintering agent in calcination to prepare the dispersible nanoparticles, strong metallic Ag peaks were observed at 38.1° and 44.3° (2θ) in the X-ray diffraction (XRD) profile. However, the Ag peak was barely observed when Ca salt was used alone as the anti-sintering agent. Thus, using Ca salt alone was more effective for preparation of dispersible Ag-HAp than PAA-Ca. The particle average size of Ag-HAp with 0.5 mol% of Ag content was found to be 325 ± 70 nm when the formation of large particleaggregations was prevented, as determined by dynamic light scattering instrument. The antibacterial activity of the Ag-HAp nanoparticles possessing 0.5 mol% against E. coli was greater than 90.0%. Dispersible and crystalline nano Ag-HAp can be obtained by using Ca salt alone as an anti-sintering agent. The nanoparticles showed antibacterial activity.

Adsorption of various types of amino acids on the graphene and boron-nitride nano-sheet, a DFT-D3 study

International Nuclear Information System (INIS)

Zhiani, Rahele

2017-01-01

Graphical abstract: Dispersion interactions have key role on the adsorption of different amino acids on the graphene and BN-nanosheet surfaces. - Highlights: • The Arginine amino acid makes the most stable complexes with Gra and BN nano sheet. • Dispersion interactions have key role on the amino acid adsorption. • BN nano sheet makes more stable complexes with amino acids compare to the Gra. • Water as a solvent has important effect on these interactions. - Abstract: The binding properties of the adsorption of five different classes of amino acids, namely, alanine (Ala), arginine (Arg), asparagine (Asn), histidine (His) and cysteine (Cys) on the surface of the graphene (Gra) and the born-nitride (BN) nano-sheet structures were studied from molecular viewpoint using quantum mechanics methods. Density functional theory (DFT) and DFT-D3 calculations were carried out to investigate the electronic properties and the dispersion interaction of the amino acid/adsorbent complexes. Several parameters affecting the interactions between the amino acids and the adsorbent surfaces such as solvent effect, adsorption energy and separation distance were investigated. Findings show that Arg forms the most stable complexes with the graphene and the BN nano-sheet compare to the other amino acids used in this study. The observed frequency results which were related to the band gap energies were consistent with the above statement. Results exhibit that adsorption of the amino acids on the surface of the BN nano-sheet and the graphene accompanied with the release of the energy. Calculations show that there are no bonded interactions between the amino acids and adsorbent surfaces. The polarity of the BN nano-sheet provides the more affinity towards the amino acids. These results were proved by the quantum chemistry studies.

Adsorption of various types of amino acids on the graphene and boron-nitride nano-sheet, a DFT-D3 study

Energy Technology Data Exchange (ETDEWEB)

Zhiani, Rahele, E-mail: r_zhiani2006@yahoo.com

2017-07-01

Graphical abstract: Dispersion interactions have key role on the adsorption of different amino acids on the graphene and BN-nanosheet surfaces. - Highlights: • The Arginine amino acid makes the most stable complexes with Gra and BN nano sheet. • Dispersion interactions have key role on the amino acid adsorption. • BN nano sheet makes more stable complexes with amino acids compare to the Gra. • Water as a solvent has important effect on these interactions. - Abstract: The binding properties of the adsorption of five different classes of amino acids, namely, alanine (Ala), arginine (Arg), asparagine (Asn), histidine (His) and cysteine (Cys) on the surface of the graphene (Gra) and the born-nitride (BN) nano-sheet structures were studied from molecular viewpoint using quantum mechanics methods. Density functional theory (DFT) and DFT-D3 calculations were carried out to investigate the electronic properties and the dispersion interaction of the amino acid/adsorbent complexes. Several parameters affecting the interactions between the amino acids and the adsorbent surfaces such as solvent effect, adsorption energy and separation distance were investigated. Findings show that Arg forms the most stable complexes with the graphene and the BN nano-sheet compare to the other amino acids used in this study. The observed frequency results which were related to the band gap energies were consistent with the above statement. Results exhibit that adsorption of the amino acids on the surface of the BN nano-sheet and the graphene accompanied with the release of the energy. Calculations show that there are no bonded interactions between the amino acids and adsorbent surfaces. The polarity of the BN nano-sheet provides the more affinity towards the amino acids. These results were proved by the quantum chemistry studies.

The physiological effects of oil, dispersant and dispersed oil on the bay mussel, Mytilus trossulus, in Arctic/Subarctic conditions.

Science.gov (United States)

Counihan, Katrina L

2018-06-01

Increasing oil development around Alaska and other Arctic regions elevates the risk for another oil spill. Dispersants are used to mitigate the impact of an oil spill by accelerating natural degradation processes, but the reduced hydrophobicity of dispersed oil may increase its bioavailability to marine organisms. There is limited research on the effect of dispersed oil on cold water species and ecosystems. Therefore, spiked exposure tests were conducted with bay mussels (Mytilus trossulus) in seawater with non-dispersed oil, Corexit 9500 and oil dispersed with different concentrations of Corexit 9500. After three weeks of exposure, acute and chronic physiological impacts were determined. The majority of physiological responses occurred during the first seven days of exposure, with mussels exhibiting significant cytochrome P450 activity, superoxide dismutase activity and heat shock protein levels. Mussels exposed to non-dispersed oil also experienced immune suppression, reduced transcription and higher levels of mortality. After 21 days, mussels in all treatments exhibited evidence of genetic damage, tissue loss and a continued stress response. Bay mussels are useful as indicators of ecosystem health and recovery, and this study was an important step in understanding how non-dispersed oil, dispersant and dispersed oil affect the physiology of this sentinel species in Arctic/subarctic conditions. Copyright © 2018 Elsevier B.V. All rights reserved.

Progress in urban dispersion studies

DEFF Research Database (Denmark)

Batchvarova, E.; Gryning, Sven-Erik

2006-01-01

The present Study addresses recent achievements in better representation Of the urban area structure in meteorology and dispersion parameterisations. The setup and Main Outcome of several recent dispersion experiments in Urban areas and their use in model validation are discussed. The maximum con...

Coping with power dispersion?

DEFF Research Database (Denmark)

2014-01-01

The last decades have witnessed a significant shift in policy competences away from central governments in Europe. The reallocation of competences spans over three dimensions: upwards; sideways; and downwards. This collection takes the dispersion of powers as a starting point and seeks to assess...... how the actors involved cope with the new configurations. In this introduction, we discuss the conceptualization of power dispersion and highlight the ways in which the contributions add to this research agenda. We then outline some general conclusions and end by indicating future avenues of research....... Taken together, the collection contributes some answers to the challenge of defining and measuring – in a comparative way – the control and co-ordination mechanisms which power dispersion generates. It also explores the tension between political actors' quest for autonomy and the acknowledgement...

Pay Dispersion and Performance in Teams

Science.gov (United States)

Bucciol, Alessandro; Foss, Nicolai J.; Piovesan, Marco

2014-01-01

Extant research offers conflicting predictions about the effect of pay dispersion on team performance. We collected a unique dataset from the Italian soccer league to study the effect of intra-firm pay dispersion on team performance, under different definitions of what constitutes a “team”. This peculiarity of our dataset can explain the conflicting evidence. Indeed, we also find positive, null, and negative effects of pay dispersion on team performance, using the same data but different definitions of team. Our results show that when the team is considered to consist of only the members who directly contribute to the outcome, high pay dispersion has a detrimental impact on team performance. Enlarging the definition of the team causes this effect to disappear or even change direction. Finally, we find that the detrimental effect of pay dispersion is due to worse individual performance, rather than a reduction of team cooperation. PMID:25397615

Viscosity and sedimentation behaviors of the magnetorheological suspensions with oleic acid/dimer acid as surfactants

Science.gov (United States)

Yang, Jianjian; Yan, Hua; Hu, Zhide; Ding, Ding

2016-11-01

This work deals with the role of polar interactions on the viscosity and sedimentation behaviors of magnetorheological suspensions with micro-sized magnetic particles dispersed in oil carriers. The oleic acid and dimer acid were employed to make an adjustment of the hydrophobicity of iron particles, in the interest of performing a comparative evaluation of the contributions of the surface polarity. The viscosity tests show that the adsorbed surfactant layer may impose a hindrance to the movement of iron particles in the oil medium. The polar attractions between dimer acid covered particles gave rise to a considerable increase in viscosity, indicating flocculation structure developed in the suspensions. The observed plateau-like region in the vicinity of 0.1 s-1 for MRF containing dimer acid is possibly due to the flocculation provoked by the carboxylic polar attraction, in which the structure is stable against fragmentation. Moreover, a quick recovery of the viscosity and a higher viscosity-temperature index also suggest the existence of particle-particle polar interaction in the suspensions containing dimer acid. The sedimentation measurements reveal that the steric repulsion of oleic acid plays a limited role in the stability of suspensions only if a large quantity of surfactant was used. The sedimentation results observed in the dimer acid covered particles confirm that loose and open flocculation was formed and enhanced sedimentation stability.

The energy-dispersive reflectometer at BESSY II: a challenge for thin film analysis

CERN Document Server

Pietsch, U; Geue, T; Neissendorfer, F; Brezsesinski, G; Symietz, C; Moehwald, H; Gudat, W

2001-01-01

Installed in 1999 the energy-dispersive reflectometer at the 13.2 bending magnet employs the exponentially decaying white X-ray emission spectrum of the 1.7 GeV storage ring of BESSY II outside the vacuum. Using an energy-dispersive detector specular and longitudinal-diffuse reflectivity spectra of thin films can be recorded simultaneously between 0.2 A sup - sup 1 acid domains. The vertical diffusion coefficient is estimated to be about 2x10 sup - sup 2 sup 4 m sup 2 /s.

Preparation and characterization of polyacrylamide-modified kaolinite containing poly [acrylic acid-co-methylene bisacrylamide] nanocomposite hydrogels

DEFF Research Database (Denmark)

Zaharia, Anamaria; Sarbu, Andrei; Radu, Anita-Laura

2015-01-01

Novel nanocomposite hydrogel structures based on cross-linked poly(acrylic acid) (PAA) and kaolinite (Kaol), modified with different loadings of polyacrylamide (PAAm), were prepared by inverse dispersion polymerization. Ceric ammonium nitrate as an initiator in the presence of nitric acid was used...... of Kaol particles in the polyacrylic acid matrix, thereby leading to enhanced interactions and furthermore to improved mechanical properties of the final hydrogels....

A reduced graphene oxide nanofiltration membrane intercalated by well-dispersed carbon nanotubes for drinking water purification

Science.gov (United States)

Chen, Xianfu; Qiu, Minghui; Ding, Hao; Fu, Kaiyun; Fan, Yiqun

2016-03-01

In this study, we report a promising rGO-CNT hybrid nanofiltration (NF) membrane that was fabricated by loading reduced graphene oxide that was intercalated with carbon nanotubes (rGO-CNTs) onto an anodic aluminum oxide (AAO) microfiltration membrane via a facile vacuum-assisted filtration process. To create this NF membrane, the CNTs were first dispersed using block copolymers (BCPs); the effects of the types and contents of BCPs used on the dispersion of CNTs have been investigated. The as-prepared rGO-CNT hybrid NF membranes were then used for drinking water purification to retain the nanoparticles, dyes, proteins, organophosphates, sugars, and particularly humic acid. Experimentally, it is shown that the rGO-CNT hybrid NF membranes have high retention efficiency, good permeability and good anti-fouling properties. The retention was above 97.3% even for methyl orange (327 Da); for other objects, the retention was above 99%. The membrane's permeability was found to be as high as 20-30 L m-2 h-1 bar-1. Based on these results, we can conclude that (i) the use of BCPs as a surfactant can enhance steric repulsion and thus disperse CNTs effectively; (ii) placing well-dispersed 1D CNTs within 2D graphene sheets allows an uniform network to form, which can provide many mass transfer channels through the continuous 3D nanostructure, resulting in the high permeability and separation performance of the rGO-CNT hybrid NF membranes.In this study, we report a promising rGO-CNT hybrid nanofiltration (NF) membrane that was fabricated by loading reduced graphene oxide that was intercalated with carbon nanotubes (rGO-CNTs) onto an anodic aluminum oxide (AAO) microfiltration membrane via a facile vacuum-assisted filtration process. To create this NF membrane, the CNTs were first dispersed using block copolymers (BCPs); the effects of the types and contents of BCPs used on the dispersion of CNTs have been investigated. The as-prepared rGO-CNT hybrid NF membranes were then used for

Axial dispersion, holdup and slip velocity of dispersed phase in a pulsed sieve plate extraction column by radiotracer residence time distribution analysis.

Science.gov (United States)

Din, Ghiyas Ud; Chughtai, Imran Rafiq; Inayat, Mansoor Hameed; Khan, Iqbal Hussain

2008-12-01

Axial dispersion, holdup and slip velocity of dispersed phase have been investigated for a range of dispersed and continuous phase superficial velocities in a pulsed sieve plate extraction column using radiotracer residence time distribution (RTD) analysis. Axial dispersion model (ADM) was used to simulate the hydrodynamics of the system. It has been observed that increase in dispersed phase superficial velocity results in a decrease in its axial dispersion and increase in its slip velocity while its holdup increases till a maximum asymptotic value is achieved. An increase in superficial velocity of continuous phase increases the axial dispersion and holdup of dispersed phase until a maximum value is obtained, while slip velocity of dispersed phase is found to decrease in the beginning and then it increases with increase in superficial velocity of continuous phase.

Spent sulfite liquor developments

Energy Technology Data Exchange (ETDEWEB)

Black, H H

1958-01-01

A review of methods of utilizing spent sulfite liquor, including evaporation and burning, fermentation to produce yeast or alcohol, production of vanillin and lignosulfonates, and use as a roadbinder.

Larval fish dispersal in a coral-reef seascape

KAUST Repository

Almany, Glenn R.; Planes, Serge; Thorrold, Simon R.; Berumen, Michael L.; Bode, Michael; Saenz Agudelo, Pablo; Bonin, Mary C.; Frisch, Ashley J.; Harrison, Hugo B.; Messmer, Vanessa; Nanninga, Gerrit B.; Priest, Mark; Srinivasan, Maya; Sinclair-Taylor, Tane; Williamson, David H.; Jones, Geoffrey P.

2017-01-01

Larval dispersal is a critical yet enigmatic process in the persistence and productivity of marine metapopulations. Empirical data on larval dispersal remain scarce, hindering the use of spatial management tools in efforts to sustain ocean biodiversity and fisheries. Here we document dispersal among subpopulations of clownfish (Amphiprion percula) and butterflyfish (Chaetodon vagabundus) from eight sites across a large seascape (10,000 km2) in Papua New Guinea across 2 years. Dispersal of clownfish was consistent between years, with mean observed dispersal distances of 15 km and 10 km in 2009 and 2011, respectively. A Laplacian statistical distribution (the dispersal kernel) predicted a mean dispersal distance of 13–19 km, with 90% of settlement occurring within 31–43 km. Mean dispersal distances were considerably greater (43–64 km) for butterflyfish, with kernels declining only gradually from spawning locations. We demonstrate that dispersal can be measured on spatial scales sufficient to inform the design of and test the performance of marine reserve networks.

Larval fish dispersal in a coral-reef seascape

KAUST Repository

Almany, Glenn R.

2017-05-23

Larval dispersal is a critical yet enigmatic process in the persistence and productivity of marine metapopulations. Empirical data on larval dispersal remain scarce, hindering the use of spatial management tools in efforts to sustain ocean biodiversity and fisheries. Here we document dispersal among subpopulations of clownfish (Amphiprion percula) and butterflyfish (Chaetodon vagabundus) from eight sites across a large seascape (10,000 km2) in Papua New Guinea across 2 years. Dispersal of clownfish was consistent between years, with mean observed dispersal distances of 15 km and 10 km in 2009 and 2011, respectively. A Laplacian statistical distribution (the dispersal kernel) predicted a mean dispersal distance of 13–19 km, with 90% of settlement occurring within 31–43 km. Mean dispersal distances were considerably greater (43–64 km) for butterflyfish, with kernels declining only gradually from spawning locations. We demonstrate that dispersal can be measured on spatial scales sufficient to inform the design of and test the performance of marine reserve networks.

Velocity Dispersions Across Bulge Types

International Nuclear Information System (INIS)

Fabricius, Maximilian; Bender, Ralf; Hopp, Ulrich; Saglia, Roberto; Drory, Niv; Fisher, David

2010-01-01

We present first results from a long-slit spectroscopic survey of bulge kinematics in local spiral galaxies. Our optical spectra were obtained at the Hobby-Eberly Telescope with the LRS spectrograph and have a velocity resolution of 45 km/s (σ*), which allows us to resolve the velocity dispersions in the bulge regions of most objects in our sample. We find that the velocity dispersion profiles in morphological classical bulge galaxies are always centrally peaked while the velocity dispersion of morphologically disk-like bulges stays relatively flat towards the center--once strongly barred galaxies are discarded.

Melt dispersion granules: formulation and evaluation to improve oral delivery of poorly soluble drugs - a case study with valsartan.

Science.gov (United States)

Chella, Naveen; Tadikonda, Ramarao

2015-06-01

Solid dispersion (SD) technique is a promising strategy to improve the solubility and dissolution of BCS class II drugs. However, only few products are marketed till today based on SD technology due to poor flow properties and stability. The present work was intended to solve these problems by using combination approach, melt dispersion and surface adsorption technologies. The main aim of the present work is to improve the absorption in the stomach (at lower pH) where the absorption window exists for the drug by improving the dissolution, resulting in the enhancement of oral bioavailability of poorly soluble, weakly acidic drug with pH dependant solubility, i.e. valsartan. Melt dispersion granules were prepared in different ratios using different carriers (Gelucire 50/13, PEG 8000 and Pluronic F-68) and lactose as an adsorbent. Similarly, physical mixtures were also prepared at corresponding ratios. The prepared dispersion granules and physical mixtures were characterized by FTIR, DSC and in vitro dissolution studies. DSC studies revealed reduction in the crystallinity with a possibility of presence of amorphous character of drug in the dispersion granules. From dissolution studies, valsartan Gelucire dispersion (GSD4; 1:4 ratio) showed complete drug release in 30 min against the plain drug which showed only 11.31% of drug release in 30 min. Pharmacokinetic studies of optimized formulation in male Wistar rats showed 2.65-fold higher bioavailability and 1.47-fold higher Cmax compared to pure drug. The melt dispersion technology has the potential to improve dissolution and the bioavailability of BCS class II drugs.

Measurement of small dispersion values in optical components

DEFF Research Database (Denmark)

Peucheret, Christophe; Liu, Fenghai; Pedersen, Rune Johan Skullerud

1999-01-01

It is reported that small dispersion values in optical components can be measured using the RF modulation method originally restricted to large dispersions. Using a constant dispersion offset, arbitrarily small dispersion values can be measured with a resolution as good as 1.2 ps/nm....

Analysis of site-specific dispersion conditions

International Nuclear Information System (INIS)

Paesler-Sauer, J.

1989-03-01

This report presents an analysis of atmospheric dispersion conditions in the environs of nuclear power stations in the Federal Republic of Germany. The analysis is based on meteorological data measured on the power station sites (KFUe = nuclear reactor remote control records) and by neighbouring stations operated by the German Weather Service. The data are series of hourly mean values of wind and temperature gradient or stability class over the period of one or more years. The aim of the data analysis is to find types of dispersion conditions characterized by the flow field and stratification, and to assess the feasibility of calculating these quantities in the case of an emergency. Influences of terrain structures in the environs of the site are considered. The annual frequencies of types of dispersion situations are assessed, the capability to recognize the dispersion situation from meteorological data measured on the site and the applicability of dispersion models are discussed. (orig.) [de

Generalization of the dispersion relations demonstration; Generalisation de la demonstration des relations de dispersion

Energy Technology Data Exchange (ETDEWEB)

Omnes, Roland [Commissariat a l' energie atomique et aux energies alternatives - CEA (France)

1960-07-01

A modification of the dispersion relations demonstration for two-particle collisions in field theory is indicated. The direct study of the holomorphy domain of the reaction amplitude, without any reference to a particular coordinate system, allows to demonstrate the dispersion relations with fixed pulse transfer for any input and output particle mass. Reprint of a paper published in Comptes rendus des seances de l'Academie des Sciences, t. 250, p. 1203-1205, sitting of 15 February 1960 [French] On indique une modification de la demonstration des relations de dispersion pour les collisions a deux particules en theorie des champs. En etudiant directement le domaine d'holomorphie de l'amplitude de reaction sans se referer a un systeme de coordonnees particulier, on demontre les relations de dispersion a transfert d'impulsion fixe dans le cas ou les masses des particules entrantes et sortantes sont quelconques. Reproduction d'un article publie dans les Comptes rendus des seances de l'Academie des Sciences, t. 250, p. 1203-1205, seance du 15 fevrier 1960.

Polymer supported sulphanilic acid: A highly efficient and recyclable ...

Indian Academy of Sciences (India)

The resulting chloromethylated styrene- divinylbenzene copolymer beads were designated as. P2 and analysed for chlorine content by Stepnow method.37. 2.3 Procedure for polymer supported sulphanilic acid (P3). P2 (5 gm) were dispersed in methanol (15 ml) and allowed to swell for 2 h. To the swollen bead, aque-.

Dispersal of sticky particles

Science.gov (United States)

Reddy, Ramana; Kumar, Sanjeev

2007-12-01

In this paper, we show through simulations that when sticky particles are broken continually, particles are dispersed into fine dust only if they are present in a narrow range of volume fractions. The upper limit of this range is 0.20 in the 2D and 0.10 in the 3D space. An increase in the dimensionality of space reduces the upper limit nearly by a factor of two. This scaling holds for dispersal of particles in hyperdimensional space of dimensions up to ten, the maximum dimension studied in this work. The maximum values of volume fractions obtained are significantly lower than those required for close packing and random packing of discs in 2D and spheres in 3D space. These values are also smaller than those required for critical phenomena of cluster percolation. The results obtained are attributed to merger cascades of sticky particles, triggered by breakup events. A simple theory that incorporates this cascade is developed to quantitatively explain the observed scaling of the upper limit with the dimensionality of space. The theory also captures the dynamics of the dispersal process in the corresponding range of particle volume fractions. The theory suggests that cascades of order one and two predominantly decide the upper limit for complete dispersal of particles.

Trajectory and Relative Dispersion Case Studies and Statistics from the Green River Mesoscale Deformation, Dispersion, and Dissipation Program

Science.gov (United States)

Niemann, Brand Lee

A major field program to study beta-mesoscale transport and dispersion over complex mountainous terrain was conducted during 1969 with the cooperation of three government agencies at the White Sands Missile Range in central Utah. The purpose of the program was to measure simultaneously on a large number of days the synoptic and mesoscale wind fields, the relative dispersion between pairs of particle trajectories and the rate of small scale turbulence dissipation. The field program included measurements during more than 60 days in the months of March, June, and November. The large quantity of data generated from this program has been processed and analyzed to provide case studies and statistics to evaluate and refine Lagrangian variable trajectory models. The case studies selected to illustrate the complexities of mesoscale transport and dispersion over complex terrain include those with terrain blocking, lee waves, and stagnation, as well as those with large vertical wind shears and horizontal wind field deformation. The statistics of relative particle dispersion were computed and compared to the classical theories of Richardson and Batchelor and the more recent theories of Lin and Kao among others. The relative particle dispersion was generally found to increase with travel time in the alongwind and crosswind directions, but in a more oscillatory than sustained or even accelerated manner as predicted by most theories, unless substantial wind shears or finite vertical separations between particles were present. The relative particle dispersion in the vertical was generally found to be small and bounded even when substantial vertical motions due to lee waves were present because of the limiting effect of stable temperature stratification. The data show that velocity shears have a more significant effect than turbulence on relative particle dispersion and that sufficient turbulence may not always be present above the planetary boundary layer for "wind direction shear

Rheological Behavior of Bentonite-Polyester Dispersions

Science.gov (United States)

Abu-Jdayil, Basim; Al-Omari, Salah Addin

2013-07-01

The rheological behavior of a bentonite clay dispersed in unsaturated polyester was investigated. The effects of the solid content and particle size on the steady and transient rheological properties of the dispersions were studied. In addition, two types of bentonite with different Na+/Ca+2 ratio were used in this study. The Herschel-Bulkley and the Weltman models were used to describe the apparent viscosity of the bentonite-polyester composite in relation to the shear rate and shearing time. The bentonite-polyester dispersions were found to exhibit both Newtonian and non-Newtonian behavior. The transition from a Newtonian to a Bingham plastic and then to a shear-thinning material with a yield stress was found to depend on the solid concentration, the particle size, and the type of bentonite. At a low solid content, the apparent viscosity of the bentonite dispersion increased linearly with solid concentration. But a dramatic increase in the apparent viscosity beyond a solid content of 20 wt.% was observed. On the other hand, a thixotropic behavior was detected in bentonite-polyester dispersions with a high solid content and a low particle size. However, this behavior was more pronounced in dispersions with a high Na+/Ca+2 ratio.

Synthesis of highly dispersed Pd nanoparticles supported on multi-walled carbon nanotubes and their excellent catalytic performance for oxidation of benzyl alcohol

NARCIS (Netherlands)

Shinde, V.M.; Skupien, E.; Makkee, M.

2015-01-01

Narrow sized and highly homogeneous dispersed Pd nanoparticles have been synthesized on nitric acid-functionalized multi-walled carbon nanotubes (CNTs) without a capping agent. The TEM images show that the extremely small Pd nanoparticles with an average size of about 1.5 nm were homogeneously

The Braer incident: Dispersion in action

International Nuclear Information System (INIS)

Thomas, D.

1993-01-01

In January 1993, the tanker Braer foundered in the Shetland Islands and pollution from the cargo of 85,000 tonnes of Gullfaks crude oil was reported almost immediately. The tanker was battered by storm winds and finally broke up, spilling the remainder of its cargo into the bay at Garth's Ness. Dispersants were applied to the oil plumes, assisting the significant natural dispersion. Shoreline protection and cleanup activities included construction of spade dams and sorbent barriers. Oil concentrations in water, air, sediment, and fish were monitored. The sampling program undertaken during the spill period is described. Measured hydrocarbon concentrations in salmon farm areas were not observed to rise above 4 ppM. The high rates of dispersion make the Braer incident worthy of detailed study both in terms of understanding the mechanism of the dispersion process and also in assessing the environmental effects following high dispersed oil concentrations. Estimates of the spill's mass balance are provided for the bay at Garth's Ness, where the highest oil concentrations were observed, and along the 26 km of coastline which received the most significant concentrations of dispersed oil. Contrary to laboratory experiments which showed that the Gullfaks crude would emulsify at the high sea states prevailing at the time, the Braer spill did not emulsify and most of the oil released was dispersed naturally into the water column. It appears that it is most appropriate to model the Braer spill as a spillage of floating or dissolved chemical. 4 refs., 4 figs., 6 tabs

The comparative effects of oil dispersants and oil/dispersant conjugates on germination of the marine macroalga Phyllospora comosa (Fucales: Phaeophyta)

International Nuclear Information System (INIS)

Burridge, T.R.; Shir, M.-A.

1995-01-01

Germination inhibition of the marine macrophyte Phyllospora comosa was utilized as a sub-lethal end-point to assess and compare the effects of four oil dispersants and dispersed diesel fuel and crude oil combinations. Inhibition of germination by the water-soluble fraction of diesel fuel increased following the addition of each of the dispersants; the nominal 48-h EC 50 concentration of diesel fuel declined from 6800 to approximately 400 μl 1 -1 nominal for each dispersed combination. This contrasted with crude oil, where the addition of two dispersants resulted in an enhanced germination rate and an increase in nominal EC 50 concentrations from 130 μl 1 -1 for the undispersed crude to 4000 and 2500 μl 1 -1 . The results indicate that, while germination inhibition of P. comosa may be enhanced by the chemical dispersal of oil response varies with type of both oil and oil dispersant. (author)

Integrating individual movement behaviour into dispersal functions.

Science.gov (United States)

Heinz, Simone K; Wissel, Christian; Conradt, Larissa; Frank, Karin

2007-04-21

Dispersal functions are an important tool for integrating dispersal into complex models of population and metapopulation dynamics. Most approaches in the literature are very simple, with the dispersal functions containing only one or two parameters which summarise all the effects of movement behaviour as for example different movement patterns or different perceptual abilities. The summarising nature of these parameters makes assessing the effect of one particular behavioural aspect difficult. We present a way of integrating movement behavioural parameters into a particular dispersal function in a simple way. Using a spatial individual-based simulation model for simulating different movement behaviours, we derive fitting functions for the functional relationship between the parameters of the dispersal function and several details of movement behaviour. This is done for three different movement patterns (loops, Archimedean spirals, random walk). Additionally, we provide measures which characterise the shape of the dispersal function and are interpretable in terms of landscape connectivity. This allows an ecological interpretation of the relationships found.

Cotton nanofibers obtained by different acid conditions

International Nuclear Information System (INIS)

Teixeira, Eliangela de M.; Oliveira, Caue Ribeiro de; Mattoso, Luiz H.C.; Correa, Ana Carolina; Palladin, Priscila

2009-01-01

The thermal stability of cellulose nanofibers is related to their application and especially to polymer processing which temperatures of processing are around 200 deg C. In this work, nanofibers of commercial cotton were obtained by acid hydrolysis employing different acids: sulfuric, hydrochloric and a mixture (2:1; sulfuric acid: hydrochloric acid).The morphology of the nanofibers were characterized by transmission microscopy (TEM), crystallinity by x-ray diffraction (XRD) and thermal stability in air atmosphere by thermogravimetric analysis (TGA). The results indicated a very similar morphology and crystallinity among them. The main differences were relative to aggregation state e and thermal stability. The aggregation state of the suspensions decreases in the order HCl 2 SO 4 :HCl 2 SO 4- . The hydrolysis with a mix of HCl and H 2 SO 4 resulted in cellulose nanofibers with higher thermal stability than those hydrolyzed with H 2 SO 4 . The hydrolysis employed with a mixture of sulphuric and hydrochloric acids also showed a better dispersion than those suspensions of nanofibers obtained by hydrolysis with only HCl. (author)

Broadening our approaches to studying dispersal in raptors

Science.gov (United States)

Morrison, J.L.; Wood, P.B.

2009-01-01

Dispersal is a behavioral process having consequences for individual fitness and population dynamics. Recent advances in technology have spawned new theoretical examinations and empirical studies of the dispersal process in birds, providing opportunities for examining how this information may be applied to studies of the dispersal process in raptors. Many raptors are the focus of conservation efforts; thus, reliable data on all aspects of a species' population dynamics, including dispersal distances, movement rates, and mortality rates of dispersers, are required for population viability analyses that are increasingly used to inform management. Here, we address emerging issues and novel approaches used in the study of avian dispersal, and provide suggestions to consider when developing and implementing studies of dispersal in raptors. Clarifying study objectives is essential for selection of an appropriate methodology and sample size needed to obtain accurate estimates of movement distances and rates. Identifying an appropriate study-area size will allow investigators to avoid underestimating population connectivity and important population parameters. Because nomadic individuals of some species use temporary settling areas or home ranges before breeding, identification of these areas is critical for conservation efforts focusing on habitats other than breeding sites. Study designs for investigating raptor dispersal also should include analysis of environmental and social factors influencing dispersal, to improve our understanding of condition-dependent dispersal strategies. Finally, we propose a terminology for use in describing the variety of movements associated with dispersal behavior in raptors, and we suggest this terminology could be used consistently to facilitate comparisons among studies. ?? 2009 The Raptor Research Foundation, Inc.

Mechanism for enhanced absorption of a solid dispersion formulation of LY2300559 using the artificial stomach duodenum model.

Science.gov (United States)

Polster, Christopher S; Wu, Sy-Juen; Gueorguieva, Ivelina; Sperry, David C

2015-04-06

An artificial stomach duodenum (ASD) model has been used to demonstrate the performance difference between two formulations of LY2300559, a low-solubility acidic developmental drug. The two formulations investigated were a conventional high-shear wet granulation (HSWG) formulation and a solid dispersion formulation. A pharmacokinetic study in humans demonstrated the enhanced performance of the solid dispersion formulation relative to the HSWG formulation. The Cmax and AUC of the solid dispersion was 2.6 and 1.9 times greater, respectively, compared to the HSWG formulation. In the ASD, the solid dispersion formulation performance was characterized by three main phases: (1) rapid release in the stomach, creating a supersaturated concentration of drug, (2) precipitation in the stomach, and (3) rapid redissolution of the precipitate in the duodenum to concentration levels that are supersaturated relative to crystalline drug. A series of complementary experiments were employed to describe this performance behavior mechanistically. Imaging experiments with a pH indicating dye showed that local pH gradients from meglumine in the solid dispersion formulation were responsible for creating a high initial supersaturation concentration in the stomach. Upon dissipation of meglumine, the drug precipitated in the stomach as an amorphous solid. Because the precipitated drug is in an amorphous form, it can then rapidly redissolve as it transits to the more neutral environment of the duodenum. This unexpected sequence of physical state changes gives a mechanistic explanation for the enhanced in vivo performance of the solid dispersion formulation relative to the HSWG formulation.

Effect of mechanical and chemical clay removals by hydrocyclone and dispersants on coal flotation

Energy Technology Data Exchange (ETDEWEB)

Oats, W.J.; Ozdemir, O.; Nguyen, A.V. [University of Queensland, Brisbane, Qld. (Australia). School of Chemical Engineering

2010-04-15

Fine minerals, mostly clays, are known to have a detrimental effect on coal flotation. This paper focuses on the effect of mechanical and chemical removals of fine minerals by hydrocyclone and dispersants on coal flotation. The experimental results showed that the flotation recovery slightly increased from medium acidic to medium alkaline ranges. The flotation experiments carried out with dispersants at different dosages showed that the dispersants did not enhance the flotation recovery significantly. However, the removal of the fine fraction from the feed using a hydrocyclone significantly increased the flotation recovery. The bubble-particle attachment tests also indicated that the attachment time between an air bubble and the coal particles increased in the presence of clay particles. These attachment time results clearly showed that the clay particles adversely affected the flotation of coal particles by covering the coal surfaces which reduced the efficiency of bubble-coal attachment. An analysis based on the colloid stability theory showed that the clay coating was governed by the van der Waals attraction and that the double-layer interaction played a secondary role. It was also concluded that the best way to increase the flotation recovery in the presence of clays was to remove these fine minerals by mechanical means such as hydrocylones.

Dispersion engineering in metamaterials and metasurfaces

Science.gov (United States)

Li, Xiong; Pu, Mingbo; Ma, Xiaoliang; Guo, Yinghui; Gao, Ping; Luo, Xiangang

2018-02-01

Dispersion engineering is essential for spectral utilization in electromagnetic systems. However, it is difficult to manage the dispersions in both natural materials and traditional electromagnetic waveguides since they are tightly related to fine structures of atoms, molecules and causality. The emergence of metamaterials and metasurfaces, which are made of subwavelength inclusions offers tremendous freedom to manipulate the electromagnetic parameters of materials and modes. Here, we review the basic principles, practical applications and recent advancements of the dispersion engineering in metadevices. The contributions of dispersion management in metadevice-based super-resolution imaging/nanolithography systems, planar functional devices, as well as the broadband perfect absorbers/polarization converters are discussed in depth. The challenges faced by this field as well as future developing trends are also presented in the conclusions.

Synthesis of colloids based on gold nanoparticles dispersed in castor oil

International Nuclear Information System (INIS)

Silva, E. C. da; Silva, M. G. A. da; Meneghetti, S. M. P.; Machado, G.; Alencar, M. A. R. C.; Hickmann, J. M.; Meneghetti, M. R.

2008-01-01

New colloidal solutions of gold nanoparticles (AuNP), using castor oil as a nontoxic organic dispersant agent, were prepared via three different methods. In all three cases, tetrachloroauric(III) acid was employed as the gold source. The colloids were characterized by UV-Vis spectroscopy and transmission electron microscopy (TEM). The AuNP produced by the three methods were quasispherical in shape, however with different average sizes. The individual characteristics of the nanoparticles presented in each colloidal system were also confirmed by observation of absorption maxima at different wavelengths of visible light. Each method of synthesis leads to colloids with different grades of stability with respect to particle agglomeration.

Simultaneous determination of 12 pharmaceuticals in water samples by ultrasound-assisted dispersive liquid-liquid microextraction coupled with ultra-high performance liquid chromatography with tandem mass spectrometry.

Science.gov (United States)

Guan, Jin; Zhang, Chi; Wang, Yang; Guo, Yiguang; Huang, Peiting; Zhao, Longshan

2016-11-01

A new analytical method was developed for simultaneous determination of 12 pharmaceuticals using ultrasound-assisted dispersive liquid-liquid microextraction (DLLME) followed by ultra-high performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS). Six nonsteroidal anti-inflammatory drugs (NSAIDs, ketoprofen, mefenamic acid, tolfenamic acid, naproxen, sulindac, and piroxicam) and six antibiotics (tinidazole, cefuroxime axetil, ciprofloxacin, sulfamethoxazole, sulfadiazine, and chloramphenicol) were extracted by ultrasound-assisted DLLME using dichloromethane (800 μL) and methanol/acetonitrile (1:1, v/v, 1200 μL) as the extraction and dispersive solvents, respectively. The factors affecting the extraction efficiency, such as the type and volume of extraction and dispersive solvent, vortex and ultrasonic time, sample pH, and ionic strength, were optimized. The ultrasound-assisted process was applied to accelerate the formation of the fine cloudy solution by using a small volume of dispersive solvent, which increased the extraction efficiency and reduced the equilibrium time. Under the optimal conditions, the calibration curves showed good linearity in the range of 0.04-20 ng mL -1 (ciprofloxacin and sulfadiazine), 0.2-100 ng mL -1 (ketoprofen, tinidazole, cefuroxime axetil, naproxen, sulfamethoxazole, and sulindac), and 1-200 ng mL -1 (mefenamic acid, tolfenamic acid, piroxicam, and chloramphenicol). The LODs and LOQs of the method were in the range of 0.006-0.091 and 0.018-0.281 ng mL -1 , respectively. The relative recoveries of the target analytes were in the range from 76.77 to 99.97 % with RSDs between 1.6 and 8.8 %. The developed method was successfully applied to the extraction and analysis of 12 pharmaceuticals in five kinds of water samples (drinking water, running water, river water, influent and effluent wastewater) with satisfactory results. Graphical Abstract Twelve pharmaceuticals in water samples analyted by UHPLC

Comparison of Dorris-Gray and Schultz methods for the calculation of surface dispersive free energy by inverse gas chromatography.

Science.gov (United States)

Shi, Baoli; Wang, Yue; Jia, Lina

2011-02-11

Inverse gas chromatography (IGC) is an important technique for the characterization of surface properties of solid materials. A standard method of surface characterization is that the surface dispersive free energy of the solid stationary phase is firstly determined by using a series of linear alkane liquids as molecular probes, and then the acid-base parameters are calculated from the dispersive parameters. However, for the calculation of surface dispersive free energy, generally, two different methods are used, which are Dorris-Gray method and Schultz method. In this paper, the results calculated from Dorris-Gray method and Schultz method are compared through calculating their ratio with their basic equations and parameters. It can be concluded that the dispersive parameters calculated with Dorris-Gray method will always be larger than the data calculated with Schultz method. When the measuring temperature increases, the ratio increases large. Compared with the parameters in solvents handbook, it seems that the traditional surface free energy parameters of n-alkanes listed in the papers using Schultz method are not enough accurate, which can be proved with a published IGC experimental result. © 2010 Elsevier B.V. All rights reserved.

Ácido sulfúrico superação da dormência de unidade de dispersão de juazeiro (Zizyphus joazeiro Mart. The use of sulfuric acid to break dispersal unit dormancy of Zizyphus joazeiro Mart.

Directory of Open Access Journals (Sweden)

Edna Ursulino Alves

2006-04-01

Full Text Available O Zizyphus joazeiro Mart. apresenta redução sensível no número de indivíduos em seu ambiente natural devido, entre outras causas, à ocorrência de dormência exógena da unidade de dispersão (impermeabilidade à água. Avaliou-se o efeito do período de imersão (0, 30, 60, 90, 120 e 150 min dessas unidades de dispersão, em ácido sulfúrico (98 %, na emergência e vigor das sementes (primeira contagem, índice de velocidade e tempo médio de emergência, altura e massa seca de plantas. O experimento foi realizado em casa de vegetação, utilizando-se o delineamento inteiramente ao acaso, com seis tratamentos e quatro repetições. O pré-condicionamento das unidades de dispersão de Zizyphus joazeiro Mart., em ácido sulfúrico concentrado, mostrou-se eficiente na superação da dormência dessa espécie, promovendo aumento na porcentagem e velocidade de emergência, primeira contagem de emergência, na altura e massa seca de plantas e redução no tempo médio para emergência. A eficiência do tratamento químico com ácido sulfúrico concentrado depende do período de imersão, sendo a faixa entre 74 e 115 min mais adequada para proporcionar maiores porcentagens de emergência e de vigor.Zizyphus joazeiro Mart. trees have been declining in number in their natural habitat due to, among other reasons, the occurrence of dormancy of dispersal units (water impermeability. The effect of the immersion time (0, 30, 60, 90, 120 and 150 minutes of Zizyphus joazeiro Mart. dispersal units in concentrated sulfuric acid (95-98 % was evaluated through the emergency and vigor (first count, speed index and mean emergence time, plant height and dry matter weight. The experiment was performed under greenhouse conditions, with a completely randomized experimental design, six treatments and four replications. The pre-conditioning of Zizyphus joazeiro Mart. dispersal units with immersion in concentrated sulfuric acid was efficient for breaking the seed

Study of isobutyric acid reactivity by electron spin resonance and infrared spectroscopy of the sodium salt and of 1-vanado-11-molybdophosphoric acid; Etude de la reactivite de l`acide isobutyrique par spectroscopie infrarouge et resonance paramagnetique electronique du sel de sodium et de l`acide de l`ion 1-vanado-11-molybdophosphorique

Energy Technology Data Exchange (ETDEWEB)

Rabia, C.; Bettahar, M.M. [Universite des sciences et de technologies, Houari-Boumediene, Algiers (Algeria); Fournier, M. [Universite des Sciences et technologies de Lille, 59 - Villeneuve d`Ascq (France)

1997-11-01

The alkaline salt 1-vanado-11-molybdo-phosphore acid as been investigated in isobutyric absorption-desorption-re-oxidation cycles by IR and ESR spectroscopies in comparison to the bulk acid compound. The stability of the active phase in catalysis seems to be related to the formation of a cubic phase depending strongly on the presence of water vapor in the gas stream. This phase can be generated from an alkali precursor subject to a moderate thermal treatment leading to a dispersion of di-oxovanadium cation into the alkali-12-molybdophosphate lattice. (authors) 14 refs.

Seed-dispersal distributions by trumpeter hornbills in fragmented landscapes

Science.gov (United States)

Lenz, Johanna; Fiedler, Wolfgang; Caprano, Tanja; Friedrichs, Wolfgang; Gaese, Bernhard H.; Wikelski, Martin; Böhning-Gaese, Katrin

2011-01-01

Frugivorous birds provide important ecosystem services by transporting seeds of fleshy fruited plants. It has been assumed that seed-dispersal kernels generated by these animals are generally leptokurtic, resulting in little dispersal among habitat fragments. However, little is known about the seed-dispersal distribution generated by large frugivorous birds in fragmented landscapes. We investigated movement and seed-dispersal patterns of trumpeter hornbills (Bycanistes bucinator) in a fragmented landscape in South Africa. Novel GPS loggers provide high-quality location data without bias against recording long-distance movements. We found a very weakly bimodal seed-dispersal distribution with potential dispersal distances up to 14.5 km. Within forest, the seed-dispersal distribution was unimodal with an expected dispersal distance of 86 m. In the fragmented agricultural landscape, the distribution was strongly bimodal with peaks at 18 and 512 m. Our results demonstrate that seed-dispersal distributions differed when birds moved in different habitat types. Seed-dispersal distances in fragmented landscapes show that transport among habitat patches is more frequent than previously assumed, allowing plants to disperse among habitat patches and to track the changing climatic conditions. PMID:21177686

Modelling airborne dispersion of coarse particulate material

International Nuclear Information System (INIS)

Apsley, D.D.

1989-03-01

Methods of modelling the airborne dispersion and deposition of coarse particulates are presented, with the emphasis on the heavy particles identified as possible constituents of releases from damaged AGR fuel. The first part of this report establishes the physical characteristics of the irradiated particulate in airborne emissions from AGR stations. The second part is less specific and describes procedures for extending current dispersion/deposition models to incorporate a coarse particulate component: the adjustment to plume spread parameters, dispersion from elevated sources and dispersion in conjunction with building effects and plume rise. (author)

Thieving rodents as substitute dispersers of megafaunal seeds

Science.gov (United States)

Jansen, Patrick A.; Hirsch, Ben T.; Emsens, Willem-Jan; Zamora-Gutierrez, Veronica; Wikelski, Martin; Kays, Roland

2012-01-01

The Neotropics have many plant species that seem to be adapted for seed dispersal by megafauna that went extinct in the late Pleistocene. Given the crucial importance of seed dispersal for plant persistence, it remains a mystery how these plants have survived more than 10,000 y without their mutualist dispersers. Here we present support for the hypothesis that secondary seed dispersal by scatter-hoarding rodents has facilitated the persistence of these large-seeded species. We used miniature radio transmitters to track the dispersal of reputedly megafaunal seeds by Central American agoutis, which scatter-hoard seeds in shallow caches in the soil throughout the forest. We found that seeds were initially cached at mostly short distances and then quickly dug up again. However, rather than eating the recovered seeds, agoutis continued to move and recache the seeds, up to 36 times. Agoutis dispersed an estimated 35% of seeds for >100 m. An estimated 14% of the cached seeds survived to the next year, when a new fruit crop became available to the rodents. Serial video-monitoring of cached seeds revealed that the stepwise dispersal was caused by agoutis repeatedly stealing and recaching each other’s buried seeds. Although previous studies suggest that rodents are poor dispersers, we demonstrate that communities of rodents can in fact provide highly effective long-distance seed dispersal. Our findings suggest that thieving scatter-hoarding rodents could substitute for extinct megafaunal seed dispersers of tropical large-seeded trees. PMID:22802644

The QT dispersion and QTc dispersion in patients presenting with acute neurological events and its impact on early prognosis

Directory of Open Access Journals (Sweden)

Kailash Kumar Rahar

2016-01-01

Full Text Available Aims: To find out and investigate whether the QT dispersion and QTc dispersion is related to type and prognosis of the acute stroke in patients presenting within 24 h of the onset of stroke. Settings and Design: This was a observational study conducted at Mahatma Gandhi Hospital, Dr. SN. Medical College, Jodhpur, during January 2014 to January 2015. Subjects and Methods: The patients presented within 24 h of onset of acute stroke (hemorrhagic, infarction, or transient ischemic event were included in the study. The stroke was confirmed by computed tomography scan and magnetic resonance imaging. Patients with (i altered sensorium because of metabolic, infective, seizures, trauma, or tumor; (ii prior history of cardiovascular disease, electrocardiographic abnormalities' because of dyselectrolytemia; and (iii and patients who were on drugs (antiarrhythmic drugs, antipsychotic drugs, erythromycin, theophylline, etc., which known to cause electrocardiogram changes, were excluded from the study. National Institute of Health Stroke Score (NIHSS was calculated at the time of admission and Modified Rankin Scale (MRS at the time of discharge. Fifty age- and sex-matched healthy controls included. Statistical Analysis Used: Student's t-test, ANOVA, and area under curve for sensitivity and specificity for the test. Results: We included 52 patients (male/female: 27/25 and 50 controls (26/24. The mean age of patients was 63.17 ± 08.90 years. Of total patients, infarct was found in 32 (61.53%, hemorrhage in 18 (34.61%, transient ischemic attack (TIA in 1 (1.9%, and subarachnoid hemorrhage in 1 (1.9% patient. The QT dispersion and QTc dispersion were significantly higher in cases as compare to controls. (87.30 ± 24.42 vs. 49.60 ± 08.79 ms; P < 0.001 and (97.53 ± 27.36 vs. 56.28 ± 09.86 ms; P < 0.001. Among various types of stroke, the mean QT dispersion and QTc dispersion were maximum and significantly higher in hemorrhagic stroke as compared to infarct and

STELLAR MASS DEPENDENT DISK DISPERSAL

International Nuclear Information System (INIS)

Kennedy, Grant M.; Kenyon, Scott J.

2009-01-01

We use published optical spectral and infrared (IR) excess data from nine young clusters and associations to study the stellar mass dependent dispersal of circumstellar disks. All clusters older than ∼3 Myr show a decrease in disk fraction with increasing stellar mass for solar to higher mass stars. This result is significant at about the 1σ level in each cluster. For the complete set of clusters we reject the null hypothesis-that solar and intermediate-mass stars lose their disks at the same rate-with 95%-99.9% confidence. To interpret this behavior, we investigate the impact of grain growth, binary companions, and photoevaporation on the evolution of disk signatures. Changes in grain growth timescales at fixed disk temperature may explain why early-type stars with IR excesses appear to evolve faster than their later-type counterparts. Little evidence that binary companions affect disk evolution suggests that photoevaporation is the more likely mechanism for disk dispersal. A simple photoevaporation model provides a good fit to the observed disk fractions for solar and intermediate-mass stars. Although the current mass-dependent disk dispersal signal is not strong, larger and more complete samples of clusters with ages of 3-5 Myr can improve the significance and provide better tests of theoretical models. In addition, the orbits of extra-solar planets can constrain models of disk dispersal and migration. We suggest that the signature of stellar mass dependent disk dispersal due to photoevaporation may be present in the orbits of observed extra-solar planets. Planets orbiting hosts more massive than ∼1.6 M sun may have larger orbits because the disks in which they formed were dispersed before they could migrate.

Estimating plume dispersion: a comparison of several sigma schemes

International Nuclear Information System (INIS)

Irwin, J.S.

1983-01-01

The lateral and vertical Gaussian plume dispersion parameters are estimated and compared with field tracer data collected at 11 sites. The dispersion parameter schemes used in this analysis include Cramer's scheme, suggested for tall stack dispersion estimates, Draxler's scheme, suggested for elevated and surface releases, Pasquill's scheme, suggested for interim use in dispersion estimates, and the Pasquill--Gifford scheme using Turner's technique for assigning stability categories. The schemes suggested by Cramer, Draxler and Pasquill estimate the dispersion parameters using onsite measurements of the vertical and lateral wind-velocity variances at the effective release height. The performances of these schemes in estimating the dispersion parameters are compared with that of the Pasquill--Gifford scheme, using the Prairie Grass and Karlsruhe data. For these two experiments, the estimates of the dispersion parameters using Draxler's scheme correlate better with the measurements than did estimates using the Pasquill--Gifford scheme. Comparison of the dispersion parameter estimates with the measurement suggests that Draxler's scheme for characterizing the dispersion results in the smallest mean fractional error in the estimated dispersion parameters and the smallest variance of the fractional errors

Strength of Drug–Polymer Interactions: Implications for Crystallization in Dispersions

Energy Technology Data Exchange (ETDEWEB)

Mistry, Pinal; Suryanarayanan, Raj

2016-09-07

We investigated the influence of the strength of drug–polymer interactions on the crystallization behavior of a model drug in amorphous solid dispersions (ASDs). Ketoconazole ASDs were prepared with each poly(acrylic acid), poly(2-hydroxyethyl methacrylate), and polyvinylpyrrolidone. Over a wide temperature range in the supercooled region, the α-relaxation time was obtained, which provided a measure of molecular mobility. Isothermal crystallization studies were performed in the same temperature interval using either a synchrotron (for low levels of crystallinity) or a laboratory X-ray (for crystallization kinetics) source. The stronger the drug–polymer interaction, the longer was the delay in crystallization onset time, indicating an increase in physical stability. Stronger drug–polymer interactions also translated to a decrease in the magnitude of the crystallization rate constant. In amorphous ketoconazole as well as in the dispersions, the coupling coefficient, a measure of the extent of coupling between relaxation and crystallization times was ~0.5. This value was unaffected by the strength of drug–polymer interactions. On the basis of these results, the crystallization times in ASDs were predicted at temperatures very close to Tg, using the coupling coefficient experimentally determined for amorphous ketoconazole. The predicted and experimental crystallization times were in good agreement, indicating the usefulness of the model.

Spectral dispersion and fringe detection in IOTA

Science.gov (United States)

Traub, W. A.; Lacasse, M. G.; Carleton, N. P.

1990-01-01

Pupil plane beam combination, spectral dispersion, detection, and fringe tracking are discussed for the IOTA interferometer. A new spectrometer design is presented in which the angular dispersion with respect to wavenumber is nearly constant. The dispersing element is a type of grism, a series combination of grating and prism, in which the constant parts of the dispersion add, but the slopes cancel. This grism is optimized for the display of channelled spectra. The dispersed fringes can be tracked by a matched-filter photon-counting correlator algorithm. This algorithm requires very few arithmetic operations per detected photon, making it well-suited for real-time fringe tracking. The algorithm is able to adapt to different stellar spectral types, intensity levels, and atmospheric time constants. The results of numerical experiments are reported.

Surface modification of zinc oxide nanoparticle by PMAA and its dispersion in aqueous system

Energy Technology Data Exchange (ETDEWEB)

Tang Erjun [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); School of Chemical and Pharmaceutical Engineering, Hebei University of Science and Technology, Shijiazhuang Hebei 050018 (China); Cheng Guoxiang [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China)]. E-mail: gxcheng@tju.edu.cn; Ma Xiaolu [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Pang Xingshou [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Zhao Qiang [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China)

2006-05-15

Commercial zinc oxide nanoparticles were modified by polymethacrylic acid (PMAA) in aqueous system. The hydroxyl groups of nano-ZnO particle surface can interact with carboxyl groups (COO-) of PMAA and form poly(zinc methacrylate) complex on the surface of nano-ZnO. The formation of poly(zinc methacrylate) complex was testified by Fourier-transform infrared spectra (FT-IR). Thermogravimetric analysis (TGA) indicated that PMAA molecules were absorbed or anchored on the surface of nano-ZnO particle, which facilitated to hinder the aggregation of nano-ZnO particles. Through particle size analysis and transmission electron micrograph (TEM) observation, it was found that PMAA enhanced the dispersibility of nano-ZnO particles in water. The dispersion stabilization of modified ZnO nanoparticles in aqueous system was significantly improved due to the introduction of grafted polymer on the surface of nanoparticles. The modification did not alter the crystalline structure of the ZnO nanoparticles according to the X-ray diffraction patterns.

Surface modification of zinc oxide nanoparticle by PMAA and its dispersion in aqueous system

Science.gov (United States)

Tang, Erjun; Cheng, Guoxiang; Ma, Xiaolu; Pang, Xingshou; Zhao, Qiang

2006-05-01

Commercial zinc oxide nanoparticles were modified by polymethacrylic acid (PMAA) in aqueous system. The hydroxyl groups of nano-ZnO particle surface can interact with carboxyl groups (COO-) of PMAA and form poly(zinc methacrylate) complex on the surface of nano-ZnO. The formation of poly(zinc methacrylate) complex was testified by Fourier-transform infrared spectra (FT-IR). Thermogravimetric analysis (TGA) indicated that PMAA molecules were absorbed or anchored on the surface of nano-ZnO particle, which facilitated to hinder the aggregation of nano-ZnO particles. Through particle size analysis and transmission electron micrograph (TEM) observation, it was found that PMAA enhanced the dispersibility of nano-ZnO particles in water. The dispersion stabilization of modified ZnO nanoparticles in aqueous system was significantly improved due to the introduction of grafted polymer on the surface of nanoparticles. The modification did not alter the crystalline structure of the ZnO nanoparticles according to the X-ray diffraction patterns.

Covalently functionalized graphene sheets with biocompatible natural amino acids

International Nuclear Information System (INIS)

Mallakpour, Shadpour; Abdolmaleki, Amir; Borandeh, Sedigheh

2014-01-01

Graphene sheets were covalently functionalized with aromatic–aliphatic amino acids (phenylalanine and tyrosine) and aliphatic amino acids (alanine, isoleucine, leucine, methionine and valine) by simple and green procedure. For this aim, at first natural graphite was converted into graphene oxide (GO) through strong oxidation procedure; then, based on the surface-exposed epoxy and carboxylic acid groups in GO solid, its surface modification with naturally occurring amino acids, occurred easily throughout the corresponding nucleophilic substitution and condensation reactions. Amino acid functionalized graphene demonstrates stable dispersion in water and common organic solvents. Fourier transform infrared, Raman and X-ray photoelectron spectroscopies, X-ray diffraction, field emission scanning electron microscopy and transmission electron microscopy were used to investigate the nanostructures and properties of prepared materials. Each amino acid has different considerable effects on the structure and morphology of the pure graphite, from increasing the layer spacing to layer scrolling, based on their structures, functional groups and chain length. In addition, therogravimetric analysis was used for demonstrating a successful grafting of amino acid molecules to the surface of graphene.

Biosorbents for Removing Hazardous Metals and Metalloids

Directory of Open Access Journals (Sweden)

Katsutoshi Inoue

2017-07-01

Full Text Available Biosorbents for remediating aquatic environmental media polluted with hazardous heavy metals and metalloids such as Pb(II, Cr(VI, Sb(III and V, and As(III and V were prepared from lignin waste, orange and apple juice residues, seaweed and persimmon and grape wastes using simple and cheap methods. A lignophenol gel such as lignocatechol gel was prepared by immobilizing the catechol functional groups onto lignin from sawdust, while lignosulfonate gel was prepared directly from waste liquor generated during pulp production. These gels effectively removed Pb(II. Orange and apple juice residues, which are rich in pectic acid, were easily converted using alkali (e.g., calcium hydroxide into biosorbents that effectively removed Pb(II. These materials also effectively removed Sb(III and V and As(III and V when these were preloaded with multi-valent metal ions such as Zr(IV and Fe(III. Similar biosorbents were prepared from seaweed waste, which is rich in alginic acid. Other biosorbents, which effectively removed Cr(VI, were prepared by simply treating persimmon and grape wastes with concentrated sulfuric acid.

Biosorbents for Removing Hazardous Metals and Metalloids †

Science.gov (United States)

Inoue, Katsutoshi; Parajuli, Durga; Ghimire, Kedar Nath; Biswas, Biplob Kumar; Kawakita, Hidetaka; Oshima, Tatsuya; Ohto, Keisuke

2017-01-01

Biosorbents for remediating aquatic environmental media polluted with hazardous heavy metals and metalloids such as Pb(II), Cr(VI), Sb(III and V), and As(III and V) were prepared from lignin waste, orange and apple juice residues, seaweed and persimmon and grape wastes using simple and cheap methods. A lignophenol gel such as lignocatechol gel was prepared by immobilizing the catechol functional groups onto lignin from sawdust, while lignosulfonate gel was prepared directly from waste liquor generated during pulp production. These gels effectively removed Pb(II). Orange and apple juice residues, which are rich in pectic acid, were easily converted using alkali (e.g., calcium hydroxide) into biosorbents that effectively removed Pb(II). These materials also effectively removed Sb(III and V) and As(III and V) when these were preloaded with multi-valent metal ions such as Zr(IV) and Fe(III). Similar biosorbents were prepared from seaweed waste, which is rich in alginic acid. Other biosorbents, which effectively removed Cr(VI), were prepared by simply treating persimmon and grape wastes with concentrated sulfuric acid. PMID:28773217

On the role of acidity in amorphous silica-alumina based catalysts

NARCIS (Netherlands)

Poduval, D.G.

2011-01-01

Amorphous silica-alumina (ASA) is widely used as a solid acid catalyst or as a carrier for well-dispersed metal sulfide or metal catalysts. They are often involved in hydrocracking catalyst formulations, especially so when the aim is to produce middle distillates from heavy oil fractions. With

Feasibility of using Ohmsett for dispersant testing and research

International Nuclear Information System (INIS)

Ross, S.L.; Buist, I.A.; Potter, S.G.; Belore, R.C.

2000-01-01

Laboratory dispersant testing proved to be of limited value for the prediction of actual dispersant effectiveness in spill situations. Variables such as oil type, weathered state, dispersant type, dispersant-to-oil ratio application method etc. were difficult to reproduce. A feasibility study was conducted at the Ohmsett facility in Leonardo, New Jersey to determine if the site was suitable for dispersant effectiveness testing. The study consisted of four phases: (1) interfacial tension laboratory tests, (2) turbidity tests, (3) the determination of the efficiency of filtering materials at the facility and alternative filtering materials, and (3) full-scale testing. Results indicated that dispersant in the water after the tests affected the interfacial tension of oils used in other tests following this one. Noticeable dispersion of floating oil occurred only after the concentration of dispersant in the water reached 400 ppm, making it possible to conduct consecutive experiments without having to worry about residual dispersant in the tank. The filtering of water to remove the dispersed oil was only required after several experiments had taken place on a given day. Evidently, it was only possible to have an underwater view of the dispersant testing during the first test of a series. The use of cellulose to aid the filtering at the facility removed most of the dispersed oil. The use of activated carbon resulted in a high degree of efficiency for the removal of dissolved dispersant. The testing of dispersant at Ohmsett proved possible as long as the design and implementation phases of the testing program respected the limitations stipulated above. 3 refs., 3 tabs., 3 figs

Ionic Liquid-Modified Thermosets and Their Nanocomposites: Dispersion, Exfoliation, Degradation, and Cure

Science.gov (United States)

Throckmorton, James A.

This dissertation explores the application of a room temperature ionic liquid (RTIL) to problems in the chemistry, processing, and modification of thermosetting polymers. In particular, the solution properties and reaction chemistry of 1-ethyl-3-methyl imidazolium dicyanamide (EMIM-DCN) are applied to problems of nanoparticle dispersion and processing, graphite exfoliation, cyanate ester (CE) cure, and the environmental degradation of CEs. Nanoparticle Dispersion: Nanocomposite processing can be simplified by using the same compound as both a nanoparticle solvent and an initiator for polymerization. This dual-function molecule can be designed both for solvent potential and reaction chemistry. EMIM-DCN, previously shown by our lab to act as an epoxy initiator, is used in the synthesis of silica and acid expanded graphite composites. These composites are then characterized for particle dispersion and physical properties. Individual particle dispersion of silica nanocomposites is shown, and silica nanocomposites at low loading show individual particle dispersion and improved modulus and fracture toughness. GNP nanocomposites show a 70% increase in modulus along with a 10-order of magnitude increase in electrical conductivity at 6.5 vol%, and an electrical percolation threshold of 1.7 vol%. Direct Graphite Exfoliation By Laminar Shear: This work presents a laminar-shear alternative to chemical processing and chaotic flow-fields for the direct exfoliation of graphite and the single-pot preparation of nanocomposites. Additionally, we develop the theory of laminar flow through a 3-roll mill, and apply that theory to the latest developments in the theory of graphite interlayer shear. The resulting nanocomposite shows low electrical percolation (0.5 vol%) and low thickness (1-3 layer) graphite/graphene flakes. Additionally, the effect of processing conditions by rheometry and comparison with solvent-free conditions reveal the interactions between processing and matrix

Long anterior zonules and pigment dispersion.

Science.gov (United States)

Moroi, Sayoko E; Lark, Kurt K; Sieving, Paul A; Nouri-Mahdavi, Kouros; Schlötzer-Schrehardt, Ursula; Katz, Gregory J; Ritch, Robert

2003-12-01

To describe pigment dispersion associated with long anterior zonules. Multicenter observational case series. Fifteen patients, seven of whom were treated for glaucoma or ocular hypertension, were identified with long anterior zonules and pigment dispersion. Transmission electron microscopy was performed on one anterior capsule specimen. All patients had anterior zonules that inserted centrally on the lens capsule. Signs of pigment dispersion included corneal endothelial pigmentation, loss of the pupillary ruff, and variable trabecular meshwork pigmentation. Ultrasound biomicroscopy verified the lack of posterior iris insertion and concavity. There was no exfoliation material. Transmission electron microscopy showed zonular lamellae with adherent pigment granules, and no exfoliation material. Long anterior zonules inserted onto the central lens capsule may cause mechanical disruption of the pigment epithelium at the pupillary ruff and central iris leading to pigment dispersion.

Electrochromic coatings made of surface modified rutile and anatase pigments: Influence of trisilanol POSS dispersant on electrochromic effect

Energy Technology Data Exchange (ETDEWEB)

Mihelčič, Mohor [National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana (Slovenia); Francetič, Vojmir [Faculty of Chemistry and Chemical Technology, University of Ljubljani, Aškerčeva cesta 5, 1000 Ljubljana (Slovenia); Pori, Pavli [Chemcolor Sevnica d.o.o., Dolenje Brezovo 35, 8290 Sevnica (Slovenia); Gradišar, Helena [National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana (Slovenia); Kovač, Janez [Jožef Stefan Institute., Jamova 39, SI-1000 Ljubljana (Slovenia); Orel, Boris, E-mail: boris.orel@ki.si [National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana (Slovenia); CO-NOT, Hajdrihova 19, Ljubljana (Slovenia)

2014-09-15

Graphical abstract: - Highlights: • Transparent pigmented coatings were deposited from titania dispersions. • Trisilanol POSS was used as dispersant. • Surface modification of pigment particles was established from TEM, TG and IR. • IR spectra studies revealed covalent and H-bond dispersant/pigment interactions. • Electrochromic properties of titanina pigment coatings were shown and discussed. - Abstract: Polyhedral oligomeric silsesqioxanes (POSS) compounds consisting of [RSiO{sub 3/2}]{sub n} groups organized in the form of various polyhedra (T{sub n}, n = 3, 6, 8, 10, 12, ….) have not often been used as pigment surface modifiers. Their interactions with pigments are not known in detail and coatings deposited from pigments modified by POSS dispersants are rare. Identification of interactions between a dispersant and the surface of pigments is important from the point of view of obtaining stable pigment dispersions enabling the deposition of optical coatings with high pigment loading, low haze and mechanical integrity. Thin TiO{sub 2} (anatase) pigment coatings (70–260 nm) were deposited from pigment dispersions prepared by milling metatitanic acid (mTiA) powder agglomerates with trisilanol heptaisobutyl silsesquioxane dispersant (trisilanol POSS) in butanol and hexane. The results of TEM, EDAX and TG measurements confirmed the influence of trisilanol POSS dispersant on the formation of a dispersion with a uniform distribution of mTiA and rutile (mTiR) nanoparticles with a size of about 30 ± 5.0 nm and 90 ± 5.0 nm, respectively, as determined from dynamic light scattering (DLS) measurements. The mTiA/trisilanol POSS dispersions with added titanium tetraisopropoxide were deposited on fluorine-doped tin oxide (FTO) coated glass (spin-coating) and indium tin oxide coated polymeric substrate (ITO PET) (coil-coating) and thermally treated at 150 °C. UV–vis spectra, AFM and SEM results showed that the pigment coatings exhibited low haze (up to 6

Electrochromic coatings made of surface modified rutile and anatase pigments: Influence of trisilanol POSS dispersant on electrochromic effect

International Nuclear Information System (INIS)

Mihelčič, Mohor; Francetič, Vojmir; Pori, Pavli; Gradišar, Helena; Kovač, Janez; Orel, Boris

2014-01-01

Graphical abstract: - Highlights: • Transparent pigmented coatings were deposited from titania dispersions. • Trisilanol POSS was used as dispersant. • Surface modification of pigment particles was established from TEM, TG and IR. • IR spectra studies revealed covalent and H-bond dispersant/pigment interactions. • Electrochromic properties of titanina pigment coatings were shown and discussed. - Abstract: Polyhedral oligomeric silsesqioxanes (POSS) compounds consisting of [RSiO 3/2 ] n groups organized in the form of various polyhedra (T n , n = 3, 6, 8, 10, 12, ….) have not often been used as pigment surface modifiers. Their interactions with pigments are not known in detail and coatings deposited from pigments modified by POSS dispersants are rare. Identification of interactions between a dispersant and the surface of pigments is important from the point of view of obtaining stable pigment dispersions enabling the deposition of optical coatings with high pigment loading, low haze and mechanical integrity. Thin TiO 2 (anatase) pigment coatings (70–260 nm) were deposited from pigment dispersions prepared by milling metatitanic acid (mTiA) powder agglomerates with trisilanol heptaisobutyl silsesquioxane dispersant (trisilanol POSS) in butanol and hexane. The results of TEM, EDAX and TG measurements confirmed the influence of trisilanol POSS dispersant on the formation of a dispersion with a uniform distribution of mTiA and rutile (mTiR) nanoparticles with a size of about 30 ± 5.0 nm and 90 ± 5.0 nm, respectively, as determined from dynamic light scattering (DLS) measurements. The mTiA/trisilanol POSS dispersions with added titanium tetraisopropoxide were deposited on fluorine-doped tin oxide (FTO) coated glass (spin-coating) and indium tin oxide coated polymeric substrate (ITO PET) (coil-coating) and thermally treated at 150 °C. UV–vis spectra, AFM and SEM results showed that the pigment coatings exhibited low haze (up to 6%), low surface

Dispersion-induced nonlinearities in semiconductors

DEFF Research Database (Denmark)

Mørk, Jesper; Mecozzi, A.

2002-01-01

A dispersive and saturable medium is shown, under very general conditions, to possess ultrafast dynamic behaviour due to non-adiabatic polarisation dynamics. Simple analytical expressions relating the effect to the refractive index dispersion of a semiconductor ire derived and the magnitude...... of the equivalent Kerr coefficient is shown to be in qualitative agreement with measurements on active semiconductor waveguides....

Definition of global dispersion coefficients

International Nuclear Information System (INIS)

Naff, R.L.

1983-10-01

For estimation of a global longitudinal dispersivity at the Gorleben site, data available primarily consist of suites of geophysical logs from wells penetrating the Quaternary aquifer. A length scale for the principle aquifer at Gorleben is to be found. Samples are to be taken separately to estimate the variance in hydraulic conductivity (Taylor Analysis, Fickian dispersion process). (DG)

Wave equation dispersion inversion using a difference approximation to the dispersion-curve misfit gradient

KAUST Repository

Zhang, Zhendong

2016-07-26

We present a surface-wave inversion method that inverts for the S-wave velocity from the Rayleigh wave dispersion curve using a difference approximation to the gradient of the misfit function. We call this wave equation inversion of skeletonized surface waves because the skeletonized dispersion curve for the fundamental-mode Rayleigh wave is inverted using finite-difference solutions to the multi-dimensional elastic wave equation. The best match between the predicted and observed dispersion curves provides the optimal S-wave velocity model. Our method can invert for lateral velocity variations and also can mitigate the local minimum problem in full waveform inversion with a reasonable computation cost for simple models. Results with synthetic and field data illustrate the benefits and limitations of this method. © 2016 Elsevier B.V.

Molecular structure of sodium lignosulfonate from different sources and their properties as dispersant of TiO2 slurry

Science.gov (United States)

Haifeng Zhou; Dongjie Yang; Junyong Zhu

2016-01-01

The molecular structure and properties of four sodium lignosulfates (LSs) derived from pulping or bioethanol production were evaluated and compared. SXP and SAL were produced by sulfite pulping and sulfonation reaction of lignin from alkali pulping of poplar, respectively. LS-180 and LS-150 were from sulfite pretreatment to overcome recalcitrance of lignocelluloses (...

Development of fast disintegrating compressed tablets using amino acid as disintegration accelerator: evaluation of wetting and disintegration of tablet on the basis of surface free energy.

Science.gov (United States)

Fukami, Jinichi; Ozawa, Asuka; Yoshihashi, Yasuo; Yonemochi, Etsuo; Terada, Katsuhide

2005-12-01

A fast disintegrating compressed tablet was formulated using amino acids, such as L-lysine HCl, L-alanine, glycine and L-tyrosine as disintegration accelerator. The tablets having the hardness of about 4 kgf were prepared and the effect of amino acids on the wetting time and disintegration time in the oral cavity of tablets was examined on the basis of surface free energy of amino acids. The wetting time of the tablets increased in the order of L-lysine HCl, L-alanine, glycine and L-tyrosine, whereas the disintegration time in the oral cavity of the tablets increased in the order of L-alanine, glycine, L-lysine HCl and L-tyrosine. These behaviors were well analyzed by the introduction of surface free energy. When the polar component of amino acid was large value or the dispersion component was small value, faster wetting of tablet was observed. When the dispersion component of amino acid was large value or the dispersion component was small value, faster disintegration of tablet was observed, expect of L-tyrosine tablet. The fast disintegration of tablets was explained by the theory presented by Matsumaru.

Modelling long-distance seed dispersal in heterogeneous landscapes.

Energy Technology Data Exchange (ETDEWEB)

Levey, Douglas, J.; Tewlsbury, Joshua, J.; Bolker, Benjamin, M.

2008-01-01

1. Long-distance seed dispersal is difficult to measure, yet key to understanding plant population dynamics and community composition. 2. We used a spatially explicit model to predict the distribution of seeds dispersed long distances by birds into habitat patches of different shapes. All patches were the same type of habitat and size, but varied in shape. They occurred in eight experimental landscapes, each with five patches of four different shapes, 150 m apart in a matrix of mature forest. The model was parameterized with smallscale movement data collected from field observations of birds. In a previous study we validated the model by testing its predictions against observed patterns of seed dispersal in real landscapes with the same types and spatial configuration of patches as in the model. 3. Here we apply the model more broadly, examining how patch shape influences the probability of seed deposition by birds into patches, how dispersal kernels (distributions of dispersal distances) vary with patch shape and starting location, and how movement of seeds between patches is affected by patch shape. 4. The model predicts that patches with corridors or other narrow extensions receive higher numbers of seeds than patches without corridors or extensions. This pattern is explained by edgefollowing behaviour of birds. Dispersal distances are generally shorter in heterogeneous landscapes (containing patchy habitat) than in homogeneous landscapes, suggesting that patches divert the movement of seed dispersers, ‘holding’ them long enough to increase the probability of seed defecation in the patches. Dispersal kernels for seeds in homogeneous landscapes were smooth, whereas those in heterogenous landscapes were irregular. In both cases, long-distance (> 150 m) dispersal was surprisingly common, usually comprising approximately 50% of all dispersal events. 5. Synthesis . Landscape heterogeneity has a large influence on patterns of long-distance seed dispersal. Our

Use of magnetic carbon composites from renewable resource materials for oil spill clean up and recovery

Science.gov (United States)

Viswanathan, Tito

2014-02-11

A method for separating a liquid hydrocarbon material from a body of water. In one embodiment, the method includes the steps of mixing a plurality of magnetic carbon-metal nanocomposites with a liquid hydrocarbon material dispersed in a body of water to allow the plurality of magnetic carbon-metal nanocomposites each to be adhered by an amount of the liquid hydrocarbon material to form a mixture, applying a magnetic force to the mixture to attract the plurality of magnetic carbon-metal nanocomposites each adhered by an amount of the liquid hydrocarbon material, and removing said plurality of magnetic carbon-metal nanocomposites each adhered by an amount of the liquid hydrocarbon material from said body of water while maintaining the applied magnetic force, wherein the plurality of magnetic carbon-metal nanocomposites is formed by subjecting one or more metal lignosulfonates or metal salts to microwave radiation, in presence of lignin/derivatives either in presence of alkali or a microwave absorbing material.

Humans as long-distance dispersers of rural plant communities.

Directory of Open Access Journals (Sweden)

Alistair G Auffret

Full Text Available Humans are known for their capacity to disperse organisms long distances. Long-distance dispersal can be important for species threatened by habitat destruction, but research into human-mediated dispersal is often focused upon few and/or invasive species. Here we use citizen science to identify the capacity for humans to disperse seeds on their clothes and footwear from a known species pool in a valuable habitat, allowing for an assessment of the fraction and types of species dispersed by humans in an alternative context. We collected material from volunteers cutting 48 species-rich meadows throughout Sweden. We counted 24,354 seeds of 197 species, representing 34% of the available species pool, including several rare and protected species. However, 71 species (36% are considered invasive elsewhere in the world. Trait analysis showed that seeds with hooks or other appendages were more likely to be dispersed by humans, as well as those with a persistent seed bank. More activity in a meadow resulted in more dispersal, both in terms of species and representation of the source communities. Average potential dispersal distances were measured at 13 km. We consider humans capable seed dispersers, transporting a significant proportion of the plant communities in which they are active, just like more traditional vectors such as livestock. When rural populations were larger, people might have been regular and effective seed dispersers, and the net rural-urban migration resulting in a reduction in humans in the landscape may have exacerbated the dispersal failure evident in declining plant populations today. With the fragmentation of habitat and changes in land use resulting from agricultural change, and the increased mobility of humans worldwide, the dispersal role of humans may have shifted from providers of regular local and landscape dispersal to providers of much rarer long-distance and regional dispersal, and international invasion.

Characterization of finite spaces having dispersion points

International Nuclear Information System (INIS)

Al-Bsoul, A. T

1997-01-01

In this paper we shall characterize the finite spaces having dispersion points. Also, we prove that the dispersion point of a finite space with a dispersion points fixed under all non constant continuous functions which answers the question raised by J. C obb and W. Voxman in 1980 affirmatively for finite space. Some open problems are given. (author). 16 refs

Carbobenzoxy amino acids: Structural requirements for cholecystokinin receptor antagonist activity

International Nuclear Information System (INIS)

Maton, P.N.; Sutliff, V.E.; Jensen, R.T.; Gardner, J.D.

1985-01-01

The authors used dispersed acini prepared from guinea pig pancreas to examine 28 carbobenzoxy (CBZ) amino acids for their abilities to function as cholecystokinin receptor antagonists. All amino acid derivatives tested, except for CBZ-alanine, CBZ-glycine, and N alpha-CBZ- lysine, were able to inhibit the stimulation of amylase secretion caused by the C-terminal octapeptide of cholecystokinin. In general, there was a good correlation between the ability of a carbobenzoxy amino acid to inhibit stimulated amylase secretion and the ability of the amino acid derivative to inhibit binding of 125 I-cholecystokinin. The inhibition of cholecystokinin-stimulated amylase secretion was competitive, fully reversible, and specific for those secretagogues that interact with the cholecystokinin receptor. The potencies with which the various carbobenzoxy amino acids inhibited the action of cholecystokinin varied 100-fold and CBZ-cystine was the most potent cholecystokinin receptor antagonist. This variation in potency was primarily but not exclusively a function of the hydrophobicity of the amino acid side chain

Fast Running Urban Dispersion Model for Radiological Dispersal Device (RDD) Releases: Model Description and Validation

Energy Technology Data Exchange (ETDEWEB)

Gowardhan, Akshay [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Atmospheric Release Advisory Center (NARAC); Neuscamman, Stephanie [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Atmospheric Release Advisory Center (NARAC); Donetti, John [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Atmospheric Release Advisory Center (NARAC); Walker, Hoyt [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Atmospheric Release Advisory Center (NARAC); Belles, Rich [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Atmospheric Release Advisory Center (NARAC); Eme, Bill [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Atmospheric Release Advisory Center (NARAC); Homann, Steven [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Atmospheric Release Advisory Center (NARAC); Simpson, Matthew [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Atmospheric Release Advisory Center (NARAC); Nasstrom, John [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Atmospheric Release Advisory Center (NARAC)

2017-05-24

Aeolus is an efficient three-dimensional computational fluid dynamics code based on finite volume method developed for predicting transport and dispersion of contaminants in a complex urban area. It solves the time dependent incompressible Navier-Stokes equation on a regular Cartesian staggered grid using a fractional step method. It also solves a scalar transport equation for temperature and using the Boussinesq approximation. The model also includes a Lagrangian dispersion model for predicting the transport and dispersion of atmospheric contaminants. The model can be run in an efficient Reynolds Average Navier-Stokes (RANS) mode with a run time of several minutes, or a more detailed Large Eddy Simulation (LES) mode with run time of hours for a typical simulation. This report describes the model components, including details on the physics models used in the code, as well as several model validation efforts. Aeolus wind and dispersion predictions are compared to field data from the Joint Urban Field Trials 2003 conducted in Oklahoma City (Allwine et al 2004) including both continuous and instantaneous releases. Newly implemented Aeolus capabilities include a decay chain model and an explosive Radiological Dispersal Device (RDD) source term; these capabilities are described. Aeolus predictions using the buoyant explosive RDD source are validated against two experimental data sets: the Green Field explosive cloud rise experiments conducted in Israel (Sharon et al 2012) and the Full-Scale RDD Field Trials conducted in Canada (Green et al 2016).

The trajectory of dispersal research in conservation biology. Systematic review.

Directory of Open Access Journals (Sweden)

Don A Driscoll

Full Text Available Dispersal knowledge is essential for conservation management, and demand is growing. But are we accumulating dispersal knowledge at a pace that can meet the demand? To answer this question we tested for changes in dispersal data collection and use over time. Our systematic review of 655 conservation-related publications compared five topics: climate change, habitat restoration, population viability analysis, land planning (systematic conservation planning and invasive species. We analysed temporal changes in the: (i questions asked by dispersal-related research; (ii methods used to study dispersal; (iii the quality of dispersal data; (iv extent that dispersal knowledge is lacking, and; (v likely consequences of limited dispersal knowledge. Research questions have changed little over time; the same problems examined in the 1990s are still being addressed. The most common methods used to study dispersal were occupancy data, expert opinion and modelling, which often provided indirect, low quality information about dispersal. Although use of genetics for estimating dispersal has increased, new ecological and genetic methods for measuring dispersal are not yet widely adopted. Almost half of the papers identified knowledge gaps related to dispersal. Limited dispersal knowledge often made it impossible to discover ecological processes or compromised conservation outcomes. The quality of dispersal data used in climate change research has increased since the 1990s. In comparison, restoration ecology inadequately addresses large-scale process, whilst the gap between knowledge accumulation and growth in applications may be increasing in land planning. To overcome apparent stagnation in collection and use of dispersal knowledge, researchers need to: (i improve the quality of available data using new approaches; (ii understand the complementarities of different methods and; (iii define the value of different kinds of dispersal information for supporting

The trajectory of dispersal research in conservation biology. Systematic review.

Science.gov (United States)

Driscoll, Don A; Banks, Sam C; Barton, Philip S; Ikin, Karen; Lentini, Pia; Lindenmayer, David B; Smith, Annabel L; Berry, Laurence E; Burns, Emma L; Edworthy, Amanda; Evans, Maldwyn J; Gibson, Rebecca; Heinsohn, Rob; Howland, Brett; Kay, Geoff; Munro, Nicola; Scheele, Ben C; Stirnemann, Ingrid; Stojanovic, Dejan; Sweaney, Nici; Villaseñor, Nélida R; Westgate, Martin J

2014-01-01

Dispersal knowledge is essential for conservation management, and demand is growing. But are we accumulating dispersal knowledge at a pace that can meet the demand? To answer this question we tested for changes in dispersal data collection and use over time. Our systematic review of 655 conservation-related publications compared five topics: climate change, habitat restoration, population viability analysis, land planning (systematic conservation planning) and invasive species. We analysed temporal changes in the: (i) questions asked by dispersal-related research; (ii) methods used to study dispersal; (iii) the quality of dispersal data; (iv) extent that dispersal knowledge is lacking, and; (v) likely consequences of limited dispersal knowledge. Research questions have changed little over time; the same problems examined in the 1990s are still being addressed. The most common methods used to study dispersal were occupancy data, expert opinion and modelling, which often provided indirect, low quality information about dispersal. Although use of genetics for estimating dispersal has increased, new ecological and genetic methods for measuring dispersal are not yet widely adopted. Almost half of the papers identified knowledge gaps related to dispersal. Limited dispersal knowledge often made it impossible to discover ecological processes or compromised conservation outcomes. The quality of dispersal data used in climate change research has increased since the 1990s. In comparison, restoration ecology inadequately addresses large-scale process, whilst the gap between knowledge accumulation and growth in applications may be increasing in land planning. To overcome apparent stagnation in collection and use of dispersal knowledge, researchers need to: (i) improve the quality of available data using new approaches; (ii) understand the complementarities of different methods and; (iii) define the value of different kinds of dispersal information for supporting management

Diffusion of organic colloids in compacted bentonite. The influence of ionic strength on molecular size and transport capacity of the colloids

International Nuclear Information System (INIS)

Wold, S.; Eriksen, Trygve E.

2000-09-01

Diffusion of radionuclides in compacted bentonite can be affected by inorganic and organic colloids if the radionuclides form complexes with the colloids. Formation and mobility of the colloid-radionuclide complexes will be governed by the properties of the colloids as well as the competition between complexation and sorption of the radionuclides on bentonite. This report presents the results of experiments with organic colloids humic acid (HA) and lignosulfonate (LS). The aim of the experiments has been to describe the HA and LS properties: size distribution, acidity, sorption on bentonite, diffusivity in compacted bentonite, complexation with strontium, and diffusion of strontium in bentonite in the presence of HA. This study indicates that the diffusion of cationic radionuclides like Sr 2+ is not affected by the presence of HA in high ionic strength solution. In 0.1 M NaClO 4 solution, HA is most probably not available for complexation due to coiling and shielding of the negative sites

Natal dispersal and personalities in great tits (Parus major)

NARCIS (Netherlands)

Dingemanse, NJ; Both, C; van Noordwijk, AJ; Rutten, AL; Drent, PJ; Noordwijk, Arie J. van; Drent, Piet J.

2003-01-01

Dispersal is a major determinant of the dynamics and genetic structure of populations, and its consequences depend not only on average dispersal rates and distances, but also on the characteristics of dispersing and philopatric individuals. We investigated whether natal dispersal correlated with a

Effect of organic solvents on dissolution process of mechano-chemically activated molybdenum by inorganic acid solutions

International Nuclear Information System (INIS)

Shevtsova, I.Ya.; Chernyak, A.S.; Khal'zov, A.A.

1992-01-01

The process of chemical dissolution of mechanochemically activated and nonactivated molybdenite by inorganic acid solutions in certain organic solvents of different nature was considered. It is shown that the highest extraction of molybdenum in solution is achieved in the presence of nitric acid. The dissociation constant of the acid used in the given organic solvent does not affect molybdenite solubility. When dissolving molybdenite by solutions of nitric acid in carbonic acids, alcohols and esters, the solubility of the concentrate depends on the length of hydrocarbon chain of the organic solvent and dispersion degree of mineral source material

Chemical dispersants

NARCIS (Netherlands)

Rahsepar, Shokouhalsadat; Smit, Martijn P.J.; Murk, Albertinka J.; Rijnaarts, Huub H.M.; Langenhoff, Alette A.M.

2016-01-01

Chemical dispersants were used in response to the Deepwater Horizon oil spill in the Gulf of Mexico, both at the sea surface and the wellhead. Their effect on oil biodegradation is unclear, as studies showed both inhibition and enhancement. This study addresses the effect of Corexit on oil

A new optical rotation dispersion formula

International Nuclear Information System (INIS)

Kimel, I.

1981-12-01

A new dispersion formula for the rotatory power is obtained in the framework of Kubo forlalism for transport coefficients. Unlike the well known Rosenfeld-Condon dispersion law, this formula is consistent with the free electron gas asymptotic behavior. (Author) [pt

Modeling the dispersal of spiny lobster (

NARCIS (Netherlands)

Whomersley, P.; van der Molen, J.; Holt, D.; Trundle, C.; Clark, S.; Fletcher, D.

2018-01-01

Knowledge of larval dispersal, population dynamics and connectivity in relation to the management and conservation of commercially important species is vital if existing fisheries are to remain sustainable into the future. Larval dispersal of the commercially exploited spiny lobster, Palinurus