40 CFR 704.43 - Chlorinated naphthalenes.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Chlorinated naphthalenes. 704.43... § 704.43 Chlorinated naphthalenes. (a) Definitions. (1) Extent of chlorination means the percent by... means the relative amounts of each isomeric chlorinated naphthalene that composes the chemical substance...

40 CFR 704.43 - Chlorinated naphthalenes.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Chlorinated naphthalenes. 704.43... § 704.43 Chlorinated naphthalenes. (a) Definitions. (1) Extent of chlorination means the percent by... means the relative amounts of each isomeric chlorinated naphthalene that composes the chemical substance...

Sulfate-Reducing Naphthalene Degraders Are Picky Eaters.

PubMed

Wolfson, Sarah J; Porter, Abigail W; Kerkhof, Lee J; McGuinness, Lora M; Prince, Roger C; Young, Lily Y

2018-06-25

Polycyclic aromatic hydrocarbons (PAHs) are common organic contaminants found in anoxic environments. The capacity for PAH biodegradation in unimpacted environments, however, has been understudied. Here we investigate the enrichment, selection, and sustainability of a microbial community from a pristine environment on naphthalene as the only amended carbon source. Pristine coastal sediments were obtained from the Jacques Cousteau National Estuarine Research Reserve in Tuckerton, New Jersey, an ecological reserve which has no direct input or source of hydrocarbons. After an initial exposure to naphthalene, primary anaerobic transfer cultures completely degraded 500 µM naphthalene within 139 days. Subsequent transfer cultures mineralized naphthalene within 21 days with stoichiometric sulfate loss. Enriched cultures efficiently utilized only naphthalene and 2-methylnaphthalene from the hydrocarbon mixtures in crude oil. To determine the microorganisms responsible for naphthalene degradation, stable isotope probing was utilized on cultures amended with fully labeled 13 C-naphthalene as substrate. Three organisms were found to unambiguously synthesize 13 C-DNA from 13 C-naphthalene within 7 days. Phylogenetic analysis revealed that 16S rRNA genes from two of these organisms are closely related to the known naphthalene degrading isolates NaphS2 and NaphS3 from PAH-contaminated sites. A third 16S rRNA gene was only distantly related to its closest relative and may represent a novel naphthalene degrading microbe from this environment.

Solubility prediction of naphthalene in carbon dioxide from crystal microstructure

NASA Astrophysics Data System (ADS)

Sang, Jiarong; Jin, Junsu; Mi, Jianguo

2018-03-01

Crystals dissolved in solvents are ubiquitous in both natural and artificial systems. Due to the complicated structures and asymmetric interactions between the crystal and solvent, it is difficult to interpret the dissolution mechanism and predict solubility using traditional theories and models. Here we use the classical density functional theory (DFT) to describe the crystal dissolution behavior. As an example, naphthalene dissolved in carbon dioxide (CO2) is considered within the DFT framework. The unit cell dimensions and microstructure of crystalline naphthalene are determined by minimizing the free-energy of the crystal. According to the microstructure, the solubilities of naphthalene in CO2 are predicted based on the equality of naphthalene's chemical potential in crystal and solution phases, and the interfacial structures and free-energies between different crystal planes and solution are determined to investigate the dissolution mechanism at the molecular level. The theoretical predictions are in general agreement with the available experimental data, implying that the present model is quantitatively reliable in describing crystal dissolution.

Electron spin resonance of gamma-irradiated poly/ethylene 2,6-naphthalene dicarboxylate/.

NASA Technical Reports Server (NTRS)

Rogowski, R. S.; Pezdirtz, G. F.

1971-01-01

The two types of radicals trapped in gamma-irradiated PEN 2,6 are identified by ESR as - O - CH - CH2 - O - (radical I) and a radical located on the naphthalene ring (radical II). The concentrations of the radicals in the gross polyer are 10 to 20% of I and 80 to 90% of II. Similar trapped radicals are established in beta-irradiated PET, a structurally related polymer.

Deposition of naphthalene and tetradecane vapors in models of the human respiratory system.

PubMed

Zhang, Zhe; Kleinstreuer, Clement

2011-01-01

Jet-propulsion fuel (particularly JP-8) is currently being used worldwide, exposing especially Air Force personnel and people living near airfields to JP-8 vapors and aerosols during aircraft fueling, maintenance operations, and/or cold starts. JP-8 is a complex mixture containing >200, mostly toxic, aliphatic and aromatic hydrocarbon compounds of which tetradecane and naphthalene were chosen as two representative chemical markers for computer simulations. Thus, transport and deposition of naphthalene and tetradecane vapors have been simulated in models of the human respiratory system. The inspiratory deposition data were analyzed in terms of regional deposition fractions (DFs) and deposition enhancement factors (DEF). The vapor depositions are affected by vapor properties (e.g. diffusivity), airway geometric features, breathing patterns, inspiratory flow rates, as well as airway-wall absorption parameter. Specifically, the respiratory uptake of vapors is greatly influenced by the degree of airway-wall absorption. For example, being an almost insoluble species in the mucus layer, the deposition of tetradecane vapor is nearly zero in the extrathoracic and tracheobronchial (TB) airways, that is, the DF is <1%. The remaining vapors may penetrate further and deposit in the alveolar airways. The DF of tetradecane vapors during inhalation in the alveolar region can range from 7% to 24%, depending on breathing waveform, inhalation rate, and thickness of the mucus layer. In contrast, naphthalene vapor almost completely deposits in the extrathoracic and TB airways and hardly moves downstream and deposits in the respiratory zone. The DFs of naphthalene vapor in the extrathoracic airways from nasal/oral to trachea under normal breathing conditions (Q = 15-60 L/min) are about 12-34%, although they are about 66-87% in the TB airways. In addition, the variation of breathing routes (say, from nasal breathing to oral breathing) may influence the vapor deposition in the

Hydration of a Large Anionic Charge Distribution - Naphthalene-Water Cluster Anions

NASA Astrophysics Data System (ADS)

Weber, J. Mathias; Adams, Christopher L.

2010-06-01

We report the infrared spectra of anionic clusters of naphthalene with up to three water molecules. Comparison of the experimental infrared spectra with theoretically predicted spectra from quantum chemistry calculations allow conclusions regarding the structures of the clusters under study. The first water molecule forms two hydrogen bonds with the π electron system of the naphthalene moiety. Subsequent water ligands interact with both the naphthalene and the other water ligands to form hydrogen bonded networks, similar to other hydrated anion clusters. Naphthalene-water anion clusters illustrate how water interacts with negative charge delocalized over a large π electron system. The clusters are interesting model systems that are discussed in the context of wetting of graphene surfaces and polyaromatic hydrocarbons.

Mechanism for Clastogenic Activity of Naphthalene

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

Buchholz, Bruce A.

2016-06-24

Naphthalene incubations form DNA adducts in vitro in a dose dependent manner in both mouse and rat tissues. Rodent tissue incubations with naphthalene indicate that naphthalene forms as many DNA adducts as Benzo(a)pyrene, a known DNA binding carcinogen. The mouse airway has the greatest number of DNA adducts, corresponding to the higher metabolic activation of naphthalene in this location. Both rat tissues, the rat olfactory (tumor target) and the airways (non-tumor target), have similar levels of NA-DNA adducts, indicating that short term measures of initial adduct formation do not directly correlate with sites of tumor formation in the NTP bioassays.

Naphthalene

Integrated Risk Information System (IRIS)

Naphthalene ; CASRN 91 - 20 - 3 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effect

PBTK Modeling Demonstrates Contribution of Dermal and Inhalation Exposure Components to End-Exhaled Breath Concentrations of Naphthalene

PubMed Central

Kim, David; Andersen, Melvin E.; Chao, Yi-Chun E.; Egeghy, Peter P.; Rappaport, Stephen M.; Nylander-French, Leena A.

2007-01-01

Background Dermal and inhalation exposure to jet propulsion fuel 8 (JP-8) have been measured in a few occupational exposure studies. However, a quantitative understanding of the relationship between external exposures and end-exhaled air concentrations has not been described for occupational and environmental exposure scenarios. Objective Our goal was to construct a physiologically based toxicokinetic (PBTK) model that quantitatively describes the relative contribution of dermal and inhalation exposures to the end-exhaled air concentrations of naphthalene among U.S. Air Force personnel. Methods The PBTK model comprised five compartments representing the stratum corneum, viable epidermis, blood, fat, and other tissues. The parameters were optimized using exclusively human exposure and biological monitoring data. Results The optimized values of parameters for naphthalene were a) permeability coefficient for the stratum corneum 6.8 × 10−5 cm/hr, b) permeability coefficient for the viable epidermis 3.0 × 10−3 cm/hr, c) fat:blood partition coefficient 25.6, and d) other tissue:blood partition coefficient 5.2. The skin permeability coefficient was comparable to the values estimated from in vitro studies. Based on simulations of workers’ exposures to JP-8 during aircraft fuel-cell maintenance operations, the median relative contribution of dermal exposure to the end-exhaled breath concentration of naphthalene was 4% (10th percentile 1% and 90th percentile 11%). Conclusions PBTK modeling allowed contributions of the end-exhaled air concentration of naphthalene to be partitioned between dermal and inhalation routes of exposure. Further study of inter- and intraindividual variations in exposure assessment is required to better characterize the toxicokinetic behavior of JP-8 components after occupational and/or environmental exposures. PMID:17589597

PBTK modeling demonstrates contribution of dermal and inhalation exposure components to end-exhaled breath concentrations of naphthalene.

PubMed

Kim, David; Andersen, Melvin E; Chao, Yi-Chun E; Egeghy, Peter P; Rappaport, Stephen M; Nylander-French, Leena A

2007-06-01

Dermal and inhalation exposure to jet propulsion fuel 8 (JP-8) have been measured in a few occupational exposure studies. However, a quantitative understanding of the relationship between external exposures and end-exhaled air concentrations has not been described for occupational and environmental exposure scenarios. Our goal was to construct a physiologically based toxicokinetic (PBTK) model that quantitatively describes the relative contribution of dermal and inhalation exposures to the end-exhaled air concentrations of naphthalene among U.S. Air Force personnel. The PBTK model comprised five compartments representing the stratum corneum, viable epidermis, blood, fat, and other tissues. The parameters were optimized using exclusively human exposure and biological monitoring data. The optimized values of parameters for naphthalene were a) permeability coefficient for the stratum corneum 6.8 x 10(-5) cm/hr, b) permeability coefficient for the viable epidermis 3.0 x 10(-3) cm/hr, c) fat:blood partition coefficient 25.6, and d) other tissue:blood partition coefficient 5.2. The skin permeability coefficient was comparable to the values estimated from in vitro studies. Based on simulations of workers' exposures to JP-8 during aircraft fuel-cell maintenance operations, the median relative contribution of dermal exposure to the end-exhaled breath concentration of naphthalene was 4% (10th percentile 1% and 90th percentile 11%). PBTK modeling allowed contributions of the end-exhaled air concentration of naphthalene to be partitioned between dermal and inhalation routes of exposure. Further study of inter- and intraindividual variations in exposure assessment is required to better characterize the toxicokinetic behavior of JP-8 components after occupational and/or environmental exposures.

Advances of naphthalene degradation in Pseudomonas putida ND6

NASA Astrophysics Data System (ADS)

Song, Fu; Shi, Yifei; Jia, Shiru; Tan, Zhilei; Zhao, Huabing

2018-03-01

Naphthalene is one of the most common and simple polycyclic aromatic hydrocarbons. Degradation of naphthalene has been greatly concerned due to its economic, free-pollution and its fine effect in Pseudomonas putida ND6. This review summarizes the development history of naphthalene degradation, the research progress of naphthalene degrading gene and naphthalene degradation pathway of Pseudomonas putida ND6, and the researching path of this strain. Although the study of naphthalene degradation is not consummate in Pseudomonas putida ND6, there is a potential capability for Pseudomonas putida ND6 to degrade the naphthalene in the further research.

Synthesis and photophysical characterizations of thermal-stable naphthalene benzimidazoles.

PubMed

Erten-Ela, Sule; Ozcelik, Serdar; Eren, Esin

2011-07-01

Microwave-assisted synthesis, photophysical and electrochemical properties of thermal-stable naphthalene benzimidazoles and naphthalimides are studied in this paper. Microwave-assisted synthesis of naphthalene benzimidazoles provide higher yields than the conventional thermal synthesis. Comparative photophysical properties of naphthalene benzimidazoles and naphthalimides are revealed that conjugation of electron-donating group onto naphthalimide moiety increases fluorescence quantum yields. Fluorophore-solvent interactions are also investigated using Lippert-Mataga equation for naphthalimides and naphthalene benzimidazoles. Thermal stabilities of naphthalene benzimidazoles are better than naphthalimides due to increased aromaticity. The experimental E(LUMO) levels of naphthalene benzimidazoles are found to be between 3.15 and 3.28 eV. Therefore, naphthalene benzimidazole derivatives consisting of anchoring groups are promising materials in organic dye sensitized solar cells. © Springer Science+Business Media, LLC 2011

Toxicity of Naphthalene and Benzene on Tribollium castaneum Herbst.

PubMed

Pajaro-Castro, Nerlis; Caballero-Gallardo, Karina; Olivero-Verbel, Jesus

2017-06-21

Naphthalene and benzene are widely-used volatile organic compounds. The aim of this research was to examine the toxicological effects of naphthalene and benzene against Tribolium castaneum as an animal model. Adult insects were exposed to these aromatic compounds to assess mortality after 4-48 h of exposure. The lethal concentration 50 (LC 50 ) for naphthalene, naphthalin, and benzene were 63.6 µL/L, 20.0 µL/L, and 115.9 µL/L in air, respectively. Real-time polymerase chain reaction (PCR) analysis revealed expression changes in genes related to oxidative stress and metabolism [Glutathione S-Transferase (Gst), and Cytochrome P450 6BQ8 (Cyp6bq8)]; reproduction and metamorphosis [Hormone receptor in 39-like protein (Hr39), Ecdysone receptor: (Ecr), and Chitin synthase 2 (Chs2)]; and neurotransmission [Histamine-gated chloride channel 2 (Hiscl2)] in insects exposed for 4 h to 70.2 µL/L naphthalene. Adults exposed to benzene (80 µL/L; 4 h) overexpressed genes related to neurotransmission [GABA-gated anion channel (Rdl), Hiscl2, and GABA-gated ion channel (Grd)]; reproduction and metamorphosis [Ultraspiracle nuclear receptor (USP), Ecr; and Hr39]; and development (Chs2). The data presented here provides evidence that naphthalene and benzene inhalation are able to induce alterations on reproduction, development, metamorphosis, oxidative stress, metabolism, neurotransmission, and death of the insect.

Experimental Electronic Spectroscopy of Two PAHs: Naphthalene and 2-METHYL Naphthalene

NASA Astrophysics Data System (ADS)

Friha, H.; Feraud, G.; Pino, T.; Brechignac, Ph.; Parneix, P.; Dhaoudi, Z.; Jaidane, N.; Galila, H.; Troy, T.; Schmidt, T.

2011-06-01

The presence of polycyclic aromatic hydrocarbons (PAHs) in the interstellar medium (ISM) was suggested in the mid-80's. Since then, their important role in the physico-chemical evolution of the ISM has been confirmed. Interstellar PAHs have been in particular proposed as possible carriers of some Diffuse Interstellar Bands (DIBs). These absorption bands are seen in the spectra of reddened stars from the visible to the near infrared and constitute a major astrophysical issue. Our purpose is to obtain electronic spectra of gas phase PAHs which will be used to probe their participation to the interstellar extinction curve from the visible (DIBs) to the UV (bump). For this goal PAHs cations represent an excellent set of target species. A new way of forming PAH+-Ar_n clusters cations has been implemented in the experimental set-up 'ICARE' at ISMO (Orsay) giving us the capability to measure the electronic spectra of cold PAH cations in the gas phase through the "Ar tagging" trick. Two molecules have been investigated in this way: naphthalene (C_1_0H_8) and 2- methyl naphthalene (C_1_1H_1_0). Clusters of naphthalene and (or 2-methyl-naphthalene) with Ar atoms are first formed in a supersonic jet, before being hit by a 281 nm laser beam which photo-ionizes the clusters which are then injected in a molecular beam through a skimmer. A tunable laser beam crossing downstream photo-dissociates the cations. The bare PAH fragments are detected using a Time-Of-Flight spectrometer while scanning the visible laser wavelength from 470 to 690 nm.

Infrared Spectroscopy of Naphthalene Aggregation and Cluster Formation in Argon Matrices

NASA Technical Reports Server (NTRS)

Roser, J. E.; Allamondola, L. J.

2011-01-01

Fourier-transform mid-infrared absorption spectra of mixed argon/naphthalene matrices at 5 K are shown with ratios of argon-to-naphthalene that vary from 1000 to 0. These spectra show the changes as naphthalene clustering and aggregation occurs, with moderate spectral shifts affecting the C-H vibrational modes and relatively small or no shifts to the C-C and C-C-C vibrational modes. The possible contribution of homogeneous naphthalene clusters to the interstellar unidentified infrared bands is discussed. The contribution of polycyclic aromatic hydrocarbon (PAH) clusters to the 7.7 micron emission plateau and the blue shading of the 12.7 micron emission band are identified as promising candidates for future research. In addition, since PAH clusters are model components of Jupiter and Titan's atmospheres, the information presented here may also be applicable to the spectroscopy of these objects.

Removal of lead and cadmium from aqueous solutions by using 4-amino-3-hydroxynaphthalene sulfonic acid-doped polypyrrole films.

PubMed

Sall, Mohamed Lamine; Diaw, Abdou Karim Diagne; Gningue-Sall, Diariatou; Chevillot-Biraud, Alexandre; Oturan, Nihal; Oturan, Mehmet Ali; Fourdrin, Chloé; Huguenot, David; Aaron, Jean-Jacques

2018-03-01

Water pollution by heavy metals is a great health concern worldwide. Lead and cadmium are among the most toxic heavy metals because they are dangerous for the human and aquatic lives. In this work, the removal of lead and cadmium from aqueous solutions has been studied using electrosynthesized 4-amino-3-hydroxynaphthalene-1-sulfonic acid-doped polypyrrole (AHNSA-PPy) films as a new adsorbent. Two distinct methods, including the immersion method, based on the Pb 2+ and Cd 2+ spontaneous removal by impregnation of the polymer in the solution, and the electro-elimination method, consisting of removal of Pb 2+ and Cd 2+ ions from the solution by applying a small electrical current (5 mA) to the polymer film, were developed: the evolution of Pb 2+ and Cd 2+ concentrations with time was monitored by inductively coupled plasma optical emission spectrometry (ICP-OES). The effect of pH on the adsorption and electro-elimination of Pb 2+ and Cd 2+ using the AHNSA-PPy film was investigated and optimized, showing that the ionic adsorption and electro-elimination processes were highly pH-dependent. The kinetics of Pb 2+ and Cd 2+ adsorption and electro-elimination were found to follow second-order curves. The maximum adsorption capacity values of the AHNSA-PPy film were 64.0 and 50.4 mg/g, respectively, for Pb 2+ and Cd 2+ . The removal efficiency values were, respectively, for Pb 2+ and Cd 2+ , 80 and 63% by the immersion method, and 93 and 85% by the electro-elimination method. Application of both methods to Senegal natural waters, fortified with Pb 2+ and Cd 2+ , led to removal efficiency values of, respectively for Pb 2+ and Cd 2+ , 76-77 and 58-59% by the immersion method, and of 82-90 and 80-83%, by the electro-elimination method.

2-(Naphthalen-1-yl)-4-(naphthalen-1-yl­methyl­idene)-1,3-oxazol-5(4H)-one

PubMed Central

Gündoğdu, Cevher; Alp, Serap; Ergün, Yavuz; Tercan, Barış; Hökelek, Tuncer

2011-01-01

In the title compound, C24H15NO2, the oxazole ring is oriented at dihedral angles of 10.09 (4) and 6.04 (4)° with respect to the mean planes of the naphthalene ring systems, while the two naphthalene ring systems make a dihedral angle of 4.32 (3)°. Intra­molecular C—H⋯N hydrogen bonds link the oxazole N atom to the naphthalene ring systems. In the crystal, inter­molecular weak C—H⋯O hydrogen bonds link the mol­ecules into centrosymmetric dimers. π–π contacts between the oxazole and naphthalene rings and between the naphthalene ring systems [centroid–centroid distances = 3.5947 (9) and 3.7981 (9) Å] may further stabilize the crystal structure. Three weak C—H⋯π inter­actions also occur. PMID:21754548

Acute intravascular hemolysis and methemoglobinemia following naphthalene ball poisoning.

PubMed

Kapoor, Rajan; Suresh, P; Barki, Satish; Mishra, Mayank; Garg, M K

2014-09-01

Naphthalene (C10H8) is a natural component of fossil fuels such as petroleum, diesel and coal. The common consumer products made from naphthalene are moth repellents, in the form of mothballs or crystals, and toilet deodorant blocks. Major toxic effects of naphthalene are due to precipitation of acute intravascular hemolysis. Very few cases of naphthalene poisoning and its effects have been reported from India. We report a case of accidental naphthalene poisoning, who presented with intravascular hemolysis and methemoglobinemia.

Naphthalene metabolism in relation to target tissue anatomy, physiology, cytotoxicity and tumorigenic mechanism of action

PubMed Central

Bogen, Kenneth T.; Benson, Janet M.; Yost, Garold S.; Morris, John B.; Dahl, Alan R.; Clewell, Harvey J.; Krishnan, Kannan; Omiecinski, Curtis J.

2014-01-01

This report provides a summary of deliberations conducted under the charge for members of Module C Panel participating in the Naphthalene State-of-the-Science Symposium (NS3), Monterey, CA, October 9–12, 2006. The panel was charged with reviewing the current state of knowledge and uncertainty about naphthalene metabolism in relation to anatomy, physiology and cytotoxicity in tissues observed to have elevated tumor incidence in these rodent bioassays. Major conclusions reached concerning scientific claims of high confidence were that: (1) rat nasal tumor occurrence was greatly enhanced, if not enabled, by adjacent, histologically related focal cellular proliferation; (2) elevated incidence of mouse lung tumors occurred at a concentration (30 ppm) cytotoxic to the same lung region at which tumors occurred, but not at a lower and less cytotoxic concentration (tumorigenesis NOAEL = 10 ppm); (3) naphthalene cytotoxicity requires metabolic activation (unmetabolized naphthalene is not a proximate cause of observed toxicity or tumors); (4) there are clear regional and species differences in naphthalene bioactivation; and (5) target tissue anatomy and physiology is sufficiently well understood for rodents, non-human primates and humans to parameterize species-specific physiologically based pharmacokinetic (PBPK) models for nasal and lung effects. Critical areas of uncertainty requiring resolution to enable improved human cancer risk assessment were considered to be that: (1) cytotoxic naphthalene metabolites, their modes of cytotoxic action, and detailed low-dose dose–response need to be clarified, including in primate and human tissues, and neonatal tissues; (2) mouse, rat, and monkey inhalation studies are needed to better define in vivo naphthalene uptake and metabolism in the upper respiratory tract; (3) in vivo validation studies are needed for a PBPK model for monkeys exposed to naphthalene by inhalation, coupled to cytotoxicity studies referred to above; and (4

Visualization of Capsule Reentry Vehicle Heat Shield Ablation Using Naphthalene PLIF

NASA Technical Reports Server (NTRS)

Combs, Christopher S.; Clemens, Noel T.; Danehy, Paul M.

2014-01-01

The Orion Multi-Purpose Crew Vehicle (MPCV) will use an ablative heat shield and improved understanding of the ablation process would be beneficial for design purposes. Given that ablation is a multi-physics process involving heat and mass transfer, codes aiming to predict heat shield ablation are in need of experimental data pertaining to the turbulent transport of ablation products for validation. At The University of Texas at Austin, a technique is being developed that uses planar laser-induced fluorescence (PLIF) of a low-temperature sublimating ablator (naphthalene) to visualize the transport of ablation products in a supersonic flow. Since ablation at reentry temperatures can be difficult to recreate in a laboratory setting it is desirable to create a limited physics problem and simulate the ablation process at relatively low temperature conditions using naphthalene. A scaled Orion MPCV model with a solid naphthalene heat shield has been tested in a Mach 5 wind tunnel at various angles of attack in the current work. PLIF imaging reveals the distribution of the ablation products as they are transported into the heat-shield boundary layer and over the capsule shoulders into the separated shear layer and backshell recirculation region. Visualizations of the capsule shear layer using both naphthalene PLIF and Schlieren imaging compared favorably. High concentrations of naphthalene in the capsule separated flow region, intermittent turbulent structures on the heat shield surface, and interesting details of the capsule shear layer structure were observed using the naphthalene PLIF technique. The capsule shear layer was also shown to generally appear to be more turbulent at lower angles of attack. Furthermore, the PLIF signal increased steadily over the course of a run indicating that during a wind tunnel run the model heated up and the rate of naphthalene ablation increased. The shear layer showed increasing signs of turbulence over the course of a wind tunnel run

Influence of the presence of PAHs and coal tar on naphthalene sorption in soils

NASA Astrophysics Data System (ADS)

Bayard, Rémy; Barna, Ligia; Mahjoub, Borhane; Gourdon, Rémy

2000-11-01

concentrations (about 120 mg/kg) in the soil. In contrast, experiments carried out with coal tar particles revealed a significant effect. Naphthalene sorption appeared to be proportional to the amount of coal tar added to the sand or soil, and a much higher affinity of naphthalene for XOM ( Koc above 2000 cm 3/g) than SOM ( Koc around 300 cm 3/g) was observed. Naphthalene transport in the columns of sand or soil spiked with coal tar particles was simulated very satisfactorily with a dual double-domain model. Around 90% of naphthalene retention by coal tar was found to occur within the organic phase, suggesting a phase partition process which may be explained by the amorphous nature of the XOM and its extreme affinity for naphthalene. For SOM, however, which is present as porous microaggregates of clay and humic substances, with less affinity for naphthalene, only 1/3 of naphthalene retention was found to occur within the organic phase, underlining the significant role of surface adsorption in the short term behavior of naphthalene in soil. For longer contact times, the model simulations proposed in the present study should be coupled to slow sorption, aging and biodegradation models to describe long-term behavior of naphthalene in soil-tar-water systems.

Poly(naphthalene diimide) vinylene: solid state red emission and semiconducting properties for transistors

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

Liang, Xianfeng; Tan, Luxi; Liu, Zitong

Here in this work, a conjugated polymer PNV is developed, linking naphthalene diimide with a vinyl linkage. Owing to the C-H ∙∙∙O hydrogen bond between the carbonyl and the vinyl, PNV exhibits a high red emission with a quantum yield of 33.4% in the solid state while it shows n-type properties with an electron mobility up to 1.5 x 10 -3 cm 2 V -1 s -1 in organic field effect transistors, simultaneously.

Poly(naphthalene diimide) vinylene: solid state red emission and semiconducting properties for transistors

DOE PAGES

Liang, Xianfeng; Tan, Luxi; Liu, Zitong; ...

2017-04-06

Here in this work, a conjugated polymer PNV is developed, linking naphthalene diimide with a vinyl linkage. Owing to the C-H ∙∙∙O hydrogen bond between the carbonyl and the vinyl, PNV exhibits a high red emission with a quantum yield of 33.4% in the solid state while it shows n-type properties with an electron mobility up to 1.5 x 10 -3 cm 2 V -1 s -1 in organic field effect transistors, simultaneously.

Synthesis, molecular modelling, and preliminary anticonvulsant activity evaluation of novel naphthalen-2-yl acetate and 1,6-dithia-4,9-diazaspiro [4.4] nonane-3,8-dione derivatives.

PubMed

Ghareb, Nagat; Abdel Daim, Mohamed M; El-Sayed, Norhan M; Elgawish, Mohamed Saleh

2017-04-01

The synthesis, pharmacological evaluation and molecular modelling study of novel naphthalen-2-yl acetate and 1,6-dithia-4,9-diazaspiro [4.4]nonane-3,8-dione derivatives as potential anticonvulsant agents are described. The newly synthesized compounds were characterized by both analytical and spectral data. Alkylation of 1H-imidazole or substituted piperazine with 1-(2-naphthyl)-2-bromoethanone (2) gave naphthalen-2-yl 2-(1H-imidazol-1-yl) acetate (3) and naphthalen-2-yl 2-(substituted piperazin-1-yl) acetate (4-8). Moreover, condensation of naphthalen-2-yl 2-bromoacetate or 2-bromo-1-(naphthalen-2-yl) ethanone with hydrazine hydrate and acetylacetone resulted in the formation of the cyclic pyrazole products 9 and 13. Sonication of naphthalen-2-yl acetate (1) with 2-chloropyridine, 2-chloropyrimidine and 2-(chloromethyl) oxirane gave naphthalen-2-yl 2-(pyridin-2-yl) acetate (10), naphthalen-2-yl 2-(pyrimidin-2-yl) acetate (11) and naphthalen-2-yl-3-(oxiran-2-yl) propanoate (12) respectively. Cyclocondensation reaction of 2-iminothiazolidin-4-one (14) with thioglycolic acid, thiolactic acid and thiomalic acid gave 1,6-dithia-4,9-diazaspiro [4.4]nonane-3,8-dione derivatives (15-17). The compounds were testedin vivofor the anticonvulsant activity by delaying strychnine-induced seizures. The diazaspirononane (17) and 1-(2-naphthyl)-2-bromoethanone (2) showed a high significant delay in the onset of convulsion and prolongation of survival time compared to phenobarbital. The molecular modelling study of anticonvulsant activity of synthesized compounds showed a CNS depressant activity via modulation of benzodiazepine allosteric site in GABA-A receptors. Copyright © 2017 Elsevier Inc. All rights reserved.

The development of a MIP-optosensor for the detection of monoamine naphthalenes in drinking water.

PubMed

Valero-Navarro, Angel; Salinas-Castillo, Alfonso; Fernández-Sánchez, Jorge F; Segura-Carretero, Antonio; Mallavia, Ricardo; Fernández-Gutiérrez, Alberto

2009-03-15

To enhance the advantages of fluorescent flow-through sensing for drinking water we have designed a novel sensing matrix based on molecularly imprinted polymers (MIPs). The synergic combination of a tailor-made MIP recognition with a selective room temperature fluorescence detection is a novel concept for optosensing devices and is assessed here for the simple and selective determination of pollutants in water. We describe a simple approach to preparing synthetic receptors for monoamine naphthalene compounds (MA-NCs) using non-covalent molecular imprinting techniques and naphthalene as template. We examine in detail the binding characteristics of the imprinted polymer and describe the flow-through sensor of MA-NCs by solid-surface fluorescence. Its detection limits for recognizing 1-naphthylamine (1-NA) and 2-naphthylamine (2-NA) separately are 26 ngmL(-1) and 50 ngmL(-1), respectively, and it also determines 1-NA and 2-NA simultaneously with a detection limit of 45 ngmL(-1). All the instrumental, chemical and flow variables were carefully optimized and an interference study was carried out to demonstrate its applicability and selectivity. Finally, we applied it to the analysis of 1-NA and 2-NA in tap and mineral waters, obtaining a 98% average recovery rate.

IRIS Toxicological Review of Naphthalene (1998 Final)

EPA Science Inventory

EPA announced the release of the final report, Toxicological Review of Naphthalene: in support of the Integrated Risk Information System (IRIS). The updated Summary for Naphthalene and accompanying toxicological review have been added to the IRIS Database.

Enrichment and identification of naphthalene-degrading bacteria from the Persian Gulf.

PubMed

Hassanshahian, Mehdi; Boroujeni, Negar Amini

2016-06-15

Naphthalene is a ubiquitous pollutant of the marine environment, and naphthalene biodegradation has been receiving constant scientific consideration. For cleanup of aromatic contaminated sites, bioremediation methods are considered as economical and safe approaches for the marine environment. The aims of this research are isolation and characterization of naphthalene-degrading bacteria from some marine samples of the Persian Gulf. Fifty four naphthalene-degrading bacteria were isolated from marine samples (sediment and seawater) that are enriched in ONR7a medium with naphthalene as the only carbon source. Some screening tests such as growth at high concentration of naphthalene, bioemulsifier production and surface hydrophobicity were done to select the best and prevalent strains for naphthalene degradation. Determination of the nucleotide sequence of the gene encoding for 16S rRNA shows that these isolated strains belong to these genera: Shewanella, Salegentibacter, Halomonas, Marinobacter, Oceanicola, Idiomarina and Thalassospira. These strains can degrade half of the percentage of naphthalene in 10days of incubation. This research is the first report on isolation of these genera from the Persian Gulf as naphthalene-degrader. Copyright © 2016 Elsevier Ltd. All rights reserved.

Comparison of the Morphology Development of Polymer-Fullerene and Polymer-Polymer Solar Cells during Solution-Shearing Blade Coating

DOE PAGES

Gu, Xiaodan; Yan, Hongping; Kurosawa, Tadanori; ...

2016-08-22

Here in this work, the detailed morphology studies of polymer poly(3-hexylthiophene-2,5-diyl) (P3HT):fullerene(PCBM) and polymer(P3HT):polymer naphthalene diimide thiophene (PNDIT) solar cell are presented to understand the challenge for getting high performance all-polymer solar cells. The in situ X-ray scattering and optical interferometry and ex situ hard and soft X-ray scattering and imaging techniques are used to characterize the bulk heterojunction (BHJ) ink during drying and in dried state. The crystallization of P3HT polymers in P3HT:PCBM bulk heterojunction shows very different behavior compared to that of P3HT:PNDIT BHJ due to different mobilities of P3HT in the donor:acceptor glass. Supplemented by the exmore » situ grazing incidence X-ray diffraction and soft X-ray scattering, PNDIT has a lower tendency to form a mixed phase with P3HT than PCBM, which may be the key to inhibit the donor polymer crystallization process, thus creating preferred small phase separation between the donor and acceptor polymer.« less

21 CFR 172.824 - Sodium mono- and dimethyl naphthalene sulfonates.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Sodium mono- and dimethyl naphthalene sulfonates... sulfonates. The food additive sodium mono- and dimethyl naphthalene sulfonates may be safely used in... statement declaring the presence of sodium mono- and dimethyl naphthalene sulfonates. [42 FR 14491, Mar. 15...

Development of Naphthalene PLIF for Visualizing Ablation Products From a Space Capsule Heat Shield

NASA Technical Reports Server (NTRS)

Combs, C. S.; Clemens, N. T.; Danehy, P. M.

2014-01-01

The Orion Multi-Purpose Crew Vehicle (MPCV) will use an ablative heat shield. To better design this heat shield and others that will undergo planetary entry, an improved understanding of the ablation process would be beneficial. Here, a technique developed at The University of Texas at Austin that uses planar laser-induced fluorescence (PLIF) of a low-temperature sublimating ablator (naphthalene) to enable visualization of the ablation products in a hypersonic flow is applied. Although high-temperature ablation is difficult and expensive to recreate in a laboratory environment, low-temperature sublimation creates a limited physics problem that can be used to explore ablation-product transport in a hypersonic flow-field. In the current work, a subscale capsule reentry vehicle model with a solid naphthalene heat shield has been tested in a Mach 5 wind tunnel. The PLIF technique provides images of the spatial distribution of sublimated naphthalene in the heat-shield boundary layer, separated shear layer, and backshell recirculation region. Visualizations of the capsule shear layer using both naphthalene PLIF and Schlieren imaging compared favorably. PLIF images have shown high concentrations of naphthalene in the capsule separated flow region, intermittent turbulent structures on the heat shield surface, and interesting details of the capsule shear layer structure. It was shown that, in general, the capsule shear layer appears to be more unsteady at lower angels of attack. The PLIF images demonstrated that during a wind tunnel run, as the model heated up, the rate of naphthalene ablation increased, since the PLIF signal increased steadily over the course of a run. Additionally, the shear layer became increasingly unsteady over the course of a wind tunnel run, likely because of increased surface roughness but also possibly because of the increased blowing. Regions with a relatively low concentration of naphthalene were also identified in the capsule backshell

Degradation of naphthalene-2,6- and naphthalene-1,6-disulfonic acid by a Moraxella sp

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

Wittich, R.M.; Tast, H.G.; Knackmuss, H.J.

1988-07-01

A naphthalene-2,6-disulfonic acid (2,6NDS)-degrading Moraxella strain was isolated from an industrial sewage plant. This culture could also be adapted to naphthalene-1,6-disulfonic acid as growth substrate. Regioselective 1,2-dioxygenation effected desulfonation and catabolism to 5-sulfosalicylic acid (5SS), which also could be used a the sole carbon source. 5SS-grown cells exhibited high gentisate 1,2-dioxygenase activity. Neither 5SS- nor gentisate-grown cells oxidized 2,6NDS; therefore, 2,6NDS or an early metabolite must serve as an inducer of the initial catabolic enzymes(s).

Development of Naphthalene PLIF for Making Quantitative Measurements of Ablation Products Transport in Supersonic Flows

NASA Astrophysics Data System (ADS)

Combs, Christopher; Clemens, Noel

2014-11-01

Ablation is a multi-physics process involving heat and mass transfer and codes aiming to predict ablation are in need of experimental data pertaining to the turbulent transport of ablation products for validation. Low-temperature sublimating ablators such as naphthalene can be used to create a limited physics problem and simulate ablation at relatively low temperature conditions. At The University of Texas at Austin, a technique is being developed that uses planar laser-induced fluorescence (PLIF) of naphthalene to visualize the transport of ablation products in a supersonic flow. In the current work, naphthalene PLIF will be used to make quantitative measurements of the concentration of ablation products in a Mach 5 turbulent boundary layer. For this technique to be used for quantitative research in supersonic wind tunnel facilities, the fluorescence properties of naphthalene must first be investigated over a wide range of state conditions and excitation wavelengths. The resulting calibration of naphthalene fluorescence will be applied to the PLIF images of ablation from a boundary layer plug, yielding 2-D fields of naphthalene mole fraction. These images may help provide data necessary to validate computational models of ablative thermal protection systems for reentry vehicles. Work supported by NASA Space Technology Research Fellowship Program under grant NNX11AN55H.

Biochemical and genotoxic response of naphthalene to fingerlings of milkfish Chanos chanos.

PubMed

Palanikumar, L; Kumaraguru, A K; Ramakritinan, C M

2013-09-01

The present study investigated the acute toxicity, sub-lethal toxicity and biochemical response of naphthalene in fingerlings of milkfish Chanos chanos. The 96 h acute toxicity LC50 values for C. chanos exposed to naphthalene was 5.18 μg l(-1). The estimated no observed effect concentration and lowest observed effect concentration values for naphthalene in C. chanos were 0.42 and 0.69 μg l(-1) respectively for 30 days. The estimated maximum allowable toxicant concentration for naphthalene was 0.53 μg l(-1). Biochemical enzyme markers such as lipid peroxidation, catalase, glutathione S transferase and reduced glutathione were measured in gills and liver tissues of C. chanos exposed to sub-lethal concentrations of naphthalene. Fluctuation in lipid peroxidation and catalase level suggests that naphthalene concentrations play a vital role in induction of oxidative stress in fish. Induction of reduced glutathione level and inhibition of glutathione S-transferase level was observed in naphthalene exposed C. chanos suggesting that there may be enhanced oxidative damage due to free radicals. Increasing concentration increases in number of nuclear abnormalities. The formation of micronuclei and binucleated micronuclei induction by naphthalene confirm its genotoxic potential. The highest levels of DNA damage (% tail length) were observed at 1.24 μg l(-1) of naphthalene. The study suggests that biochemical enzymes, nuclear abnormalities and DNA damage index can serve as a biological marker for naphthalene contamination.

Structure-Activity Relationship Studies and Molecular Modeling of Naphthalene-Based Sphingosine Kinase 2 Inhibitors.

PubMed

Congdon, Molly D; Kharel, Yugesh; Brown, Anne M; Lewis, Stephanie N; Bevan, David R; Lynch, Kevin R; Santos, Webster L

2016-03-10

The two isoforms of sphingosine kinase (SphK1 and SphK2) are the only enzymes that phosphorylate sphingosine to sphingosine-1-phosphate (S1P), which is a pleiotropic lipid mediator involved in a broad range of cellular processes including migration, proliferation, and inflammation. SphKs are targets for various diseases such as cancer, fibrosis, and Alzheimer's and sickle cell disease. Herein, we disclose the structure-activity profile of naphthalene-containing SphK inhibitors and molecular modeling studies that reveal a key molecular switch that controls SphK selectivity.

Quantification of biodegradation for o-xylene and naphthalene using first order decay models, Michaelis-Menten kinetics and stable carbon isotopes.

PubMed

Blum, Philipp; Hunkeler, Daniel; Weede, Matthias; Beyer, Christof; Grathwohl, Peter; Morasch, Barbara

2009-04-01

At a former wood preservation plant severely contaminated with coal tar oil, in situ bulk attenuation and biodegradation rate constants for several monoaromatic (BTEX) and polyaromatic hydrocarbons (PAH) were determined using (1) classical first order decay models, (2) Michaelis-Menten degradation kinetics (MM), and (3) stable carbon isotopes, for o-xylene and naphthalene. The first order bulk attenuation rate constant for o-xylene was calculated to be 0.0025 d(-1) and a novel stable isotope-based first order model, which also accounted for the respective redox conditions, resulted in a slightly smaller biodegradation rate constant of 0.0019 d(-1). Based on MM-kinetics, the o-xylene concentration decreased with a maximum rate of k(max)=0.1 microg/L/d. The bulk attenuation rate constant of naphthalene retrieved from the classical first order decay model was 0.0038 d(-1). The stable isotope-based biodegradation rate constant of 0.0027 d(-1) was smaller in the reduced zone, while residual naphthalene in the oxic part of the plume further downgradient was degraded at a higher rate of 0.0038 d(-1). With MM-kinetics a maximum degradation rate of k(max)=12 microg/L/d was determined. Although best fits were obtained by MM-kinetics, we consider the carbon stable isotope-based approach more appropriate as it is specific for biodegradation (not overall attenuation) and at the same time accounts for the dominant electron-accepting process. For o-xylene a field based isotope enrichment factor epsilon(field) of -1.4 could be determined using the Rayleigh model, which closely matched values from laboratory studies of o-xylene degradation under sulfate-reducing conditions.

[Risk analysis of naphthalene pollution in soils of Tianjin].

PubMed

Yang, Yu; Shi, Xuan; Xu, Fu-liu; Tao, Shu

2004-03-01

Three approaches were applied and evaluated for probabilistic risk assessment of naphthalene in soils of Tianjin, China, based on the observed naphthalene concentration of 188 top soil samples from the area and LC50 of naphthalene to ten typical soil fauna species from the literature. It was found that the overlapping area of the two probability density functions of concentration and LC50 was 6.4%, the joint probability curve bend towards and very close to the bottom and left axis, and the calculated probability that exposure concentration exceeds LC50 of various species was as low as 1.67%, all indicating a very much acceptable risk of naphthalene to the soil fauna ecosystem and only some of very sensitive species or individual animals are threaten by localized extremely high concentration. The three approaches revealed similar results from different viewpoints.

Binding mode dependent signaling for the detection of Cu2 +: An experimental and theoretical approach with practical applications

NASA Astrophysics Data System (ADS)

Ghosh, Soumen; Khan, Mehebub Ali; Ganguly, Aniruddha; Masum, Abdulla Al; Alam, Md. Akhtarul; Guchhait, Nikhil

2018-02-01

Two amido-schiff bases (3-Hydroxy-naphthalene-2-carboxylic acid pyren-1-ylmethylene-hydrazide and Naphthalene-2-carboxylic acid pyren-1-ylmethylene-hydrazide) have been synthesized having a common structural unit and only differs by a -OH group in the naphthalene ring. Both of them can detect Cu2 + ion selectively in semi-aqueous medium in distinctly different output modes (one detects Cu2 + by naked-eye color change where as the other detects Cu2 + by fluorescence enhancement). The difference in the binding of Cu 2 + with the compounds is the reason for this observation. The detection limit is found to be micromolar region for compound which contains -OH group whereas the compound without -OH group detects copper in nano-molar region. DFT calculations have been performed in order to demonstrate the structure of the compounds and their copper complexes. Practical utility has been explored by successful paper strip response of both the compounds. The biological applications have been evaluated in RAW 264.7.

Theoretical Study of the Electronic Spectra of a Polycyclic Aromatic Hydrocarbon, Naphthalene, and its Derivatives

NASA Technical Reports Server (NTRS)

Du, Ping; Salama, Farid; Loew, Gilda H.

1993-01-01

In order to preselect possible candidates for the origin of diffuse interstellar bands observed, semiempirical quantum mechanical method INDO/S was applied to the optical spectra of neutral, cationic, and anionic states of naphthalene and its hydrogen abstraction and addition derivatives. Comparison with experiment shows that the spectra of naphthalene and its ions were reliably predicted. The configuration interaction calculations with single-electron excitations provided reasonable excited state wavefunctions compared to ab initio calculations that included higher excitations. The degree of similarity of the predicted spectra of the hydrogen abstraction and derivatives to those of naphthalene and ions depends largely on the similarity of the it electron configurations. For the hydrogen addition derivatives, very little resemblance of the predicted spectra to naphthalene was found because of the disruption of the aromatic conjugation system. The relevance of these calculations to astrophysical issues is discussed within the context of these polycyclic aromatic hydrocarbon models. Comparing the calculated electronic energies to the Diffuse Interstellar Bands (DIBs), a list of possible candidates of naphthalene derivatives is established which provides selected candidates for a definitive test through laboratory studies.

Kinetics of chromate reduction during naphthalene degradation in a mixed culture

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

Shen, H.; Sewell, G.W.; Pritchard, P.H.

A mixed culture of Bacillus sp. K1 and Sphingomonas paucimobilis EPA 505 was exposed to chromate and naphthalene. Batch experiments showed that chromate was reduced and naphthalene was degraded by the mixed culture. Chromate reduction occurred initially at a high rate followed by a decrease in rate until chromate reduction ceased. Chromate reduction decreased in the mixed culture when a lower ratio of S. paucimobilis EPA 505 to Bacillus sp. K1 was utilized. A kinetic model incorporating a term for the cell density ratio is proposed to describe chromate reduction in the mixed culture under both chromate limited and electronmore » donor limited conditions. The validity of the model, and its parameter values, was verified by experimental data generated under a variety of initial population compositions and a broad range of chromate concentrations. The consistent result of experimental data with model predictions implies that the model is useful for evaluating the interactions and the use of mixed culture for chromate removal.« less

Toxicity and metabolism of methylnaphthalenes: Comparison with naphthalene and 1-nitronaphthalene

PubMed Central

Lin, Ching Yu; Wheelock, Åsa M.; Morin, Dexter; Baldwin, R. Michael; Lee, Myong Gong; Taff, Aysha; Plopper, Charles; Buckpitt, Alan; Rohde, Arlean

2009-01-01

Naphthalene and close structural analogues have been shown to cause necrosis of bronchiolar epithelial cells in mice by both inhalation exposure and by systemic administration. Cancer bioassays of naphthalene in mice have demonstrated a slight increase in bronchiolar/alveolar adenomas in female mice, and in inflammation and metaplasia of the olfactory epithelium in the nasal cavity. Similar work in rats demonstrated a significant, and concentration-dependent increase in the incidence of respiratory epithelial adenomas and neuroblastomas in the nasal epithelium of both male and female rats. Although the studies on the acute toxicity of the methylnaphthalene derivatives are more limited, it appears that the species selective toxicity associated with naphthalene administration also is observed with methylnaphthalenes. Chronic administration of the methylnaphthalenes, however, failed to demonstrate the same oncogenic potential as that observed with naphthalene. The information available on the isopropylnaphthalene derivatives suggests that they are not cytotoxic. Like the methylnaphthalenes, 1-nitronaphthalene causes lesions in both Clara and ciliated cells. However, the species selective lung toxicity observed in the mouse with both naphthalene and the methylnaphthalenes is not seen with 1-nitronaphthalene. With 1-nitronaphthalene, the rat is far more susceptible to parenteral administration of the compound than mice. The wide-spread distribution of these compounds in the environment and the high potential for low level exposure to humans supports a need for further work on the mechanisms of toxicity in animal models with attention to whether these processes are applicable to humans. Although it is tempting to suppose that the toxicity and mechanisms of toxicity of the alkylnaphthalenes and nitronaphthalenes are similar to naphthalene, there is sufficient published literature to suggest that this may not be the case. Certainly the enzymes involved in the metabolic

Extended Hansen solubility approach: naphthalene in individual solvents.

PubMed

Martin, A; Wu, P L; Adjei, A; Beerbower, A; Prausnitz, J M

1981-11-01

A multiple regression method using Hansen partial solubility parameters, delta D, delta p, and delta H, was used to reproduce the solubilities of naphthalene in pure polar and nonpolar solvents and to predict its solubility in untested solvents. The method, called the extended Hansen approach, was compared with the extended Hildebrand solubility approach and the universal-functional-group-activity-coefficient (UNIFAC) method. The Hildebrand regular solution theory was also used to calculate naphthalene solubility. Naphthalene, an aromatic molecule having no side chains or functional groups, is "well-behaved', i.e., its solubility in active solvents known to interact with drug molecules is fairly regular. Because of its simplicity, naphthalene is a suitable solute with which to initiate the difficult study of solubility phenomena. The three methods tested (Hildebrand regular solution theory was introduced only for comparison of solubilities in regular solution) yielded similar results, reproducing naphthalene solubilities within approximately 30% of literature values. In some cases, however, the error was considerably greater. The UNIFAC calculation is superior in that it requires only the solute's heat of fusion, the melting point, and a knowledge of chemical structures of solute and solvent. The extended Hansen and extended Hildebrand methods need experimental solubility data on which to carry out regression analysis. The extended Hansen approach was the method of second choice because of its adaptability to solutes and solvents from various classes. Sample calculations are included to illustrate methods of predicting solubilities in untested solvents at various temperatures. The UNIFAC method was successful in this regard.

4-(Naphthalene-2-carboxamido)­pyridin-1-ium thio­cyanate–N-(pyridin-4-yl)naphthalene-2-carboxamide (1/1)

PubMed Central

Saeed, Sohail; Rashid, Naghmana; Butcher, Ray J.; Öztürk Yildirim, Sema; Hussain, Rizwan

2012-01-01

The asymmetric unit of the title compound, C16H13N2O+·NCS−·C16H12N2O, contains two N-(pyridin-4-yl)naphthalene-2-carboxamide mol­ecules, both are partially protonated in the pyridine moiety, i.e. the H atom attached to the pyridine N atom is partially occupied with an occupancy factor of 0.61 (3) and 0.39 (3), respectively. In the crystal, protonated and neutral N-(pyridin-4-yl)naphthalene-2-carboxamide mol­ecules are linked by N—H⋯N hydrogen bonding; the thio­cyanate counter-ion links with both protonated and neutral N-(pyridin-4-yl)naphthalene-2-carboxamide mol­ecules via N—H⋯S and N—H⋯N hydrogen bonding. The dihedral angles between the pyridine ring and naphthalene ring systems are 11.33 (6) and 9.51 (6)°, respectively. π–π stacking is observed in the crystal structure, the shortest centroid–centroid distance being 3.5929 (8) Å. The crystal structure was determined from a nonmerohedral twin {ratio of the twin components = 0.357 (1):0.643 (1) and twin law [-100 0-10 -101]}. PMID:23125774

Comparative Biochemistry and Metabolism. Part 2. Naphthalene Lung Toxicity.

DTIC Science & Technology

1985-11-01

Metabolites to Intra- and Extracellular Proteins .............. ........ 18 Thiol Status in Isolated Hepatocytes Incubated with Naphthalene or Menadione ...Viabilities of isolated hepatocytes incubated with menadione and varying concentrations of n aphthalene...23 15 Intracellular reduced glutathione levels in hepa- tocytes incubated in the presence of menadione or varying concentrations of naphthalene

Biodegradation of naphthalene and phenanthren by Bacillus subtilis 3KP

NASA Astrophysics Data System (ADS)

Ni'matuzahroh, Trikurniadewi, N.; Pramadita, A. R. A.; Pratiwi, I. A.; Salamun, Fatimah, Sumarsih, Sri

2017-06-01

The purposes of this research were to know growth response, degradation ability, and uptake mechanism of naphthalene and phenanthrene by Bacillus subtilis 3KP. Bacillus subtilis 3KP was grown on Mineral Synthetic (MS) medium with addition of 1% yeast extract and naphthalene and phenanthrene respectively 200 ppm in different cultures. Bacillus subtilis 3KP growth response was monitored by Total Plate Count (TPC) method, the degradation ability was monitored by UV-Vis spectrophotometer, and the uptake mechanism of hydrocarbon was monitored by emulsification activity, decrease of surface tension, and activity of Bacterial Adherence to Hydrocarbon (BATH). Bacillus subtilis 3KP was able to grow and show biphasic growth pattern on both of substrates. Naphthalene and phenanthrene were used as a carbon source for Bacillus subtilis 3KP growth that indicated by the reduction of substrate concomitant with the growth. At room temperature conditions (± 30°C) and 90 rpm of agitation for 7 days, Bacillus subtilis 3KP could degrade naphthalene in the amount of 70.5% and phenanthrene in the amount of 24.8%. Based on the analysis of UV-Vis spectrophotometer, three metabolites, 1-hydroxy-2-naphthoic acid, salicylic acid, and pyrocatechol were found in both cultures. The metabolite identification became basis of propose degradation pathway of naphthalene and phenanthrene by Bacillus subtilis 3KP. The results of hydrocarbon uptake mechanism test show that Bacillus subtilis 3KP used all of the mechanism to degrade naphthalene and phenanthrene.

Combination of degradation pathways for naphthalene utilization in Rhodococcus sp. strain TFB

PubMed Central

Tomás-Gallardo, Laura; Gómez-Álvarez, Helena; Santero, Eduardo; Floriano, Belén

2014-01-01

Rhodococcus sp. strain TFB is a metabolic versatile bacterium able to grow on naphthalene as the only carbon and energy source. Applying proteomic, genetic and biochemical approaches, we propose in this paper that, at least, three coordinated but independently regulated set of genes are combined to degrade naphthalene in TFB. First, proteins involved in tetralin degradation are also induced by naphthalene and may carry out its conversion to salicylaldehyde. This is the only part of the naphthalene degradation pathway showing glucose catabolite repression. Second, a salicylaldehyde dehydrogenase activity that converts salicylaldehyde to salicylate is detected in naphthalene-grown cells but not in tetralin-or salicylate-grown cells. Finally, we describe the chromosomally located nag genes, encoding the gentisate pathway for salicylate conversion into fumarate and pyruvate, which are only induced by salicylate and not by naphthalene. This work shows how biodegradation pathways in Rhodococcus sp. strain TFB could be assembled using elements from different pathways mainly because of the laxity of the regulatory systems and the broad specificity of the catabolic enzymes. PMID:24325207

Time-resolved spectroscopy of solid poly/1-vinyl naphthalene/ following electron beam pulse radiolysis - Pulse radiolytic studies on polymers

NASA Technical Reports Server (NTRS)

Coulter, D. R.; Liang, R. H.; Di Stefano, S.; Moacanin, J.; Gupta, A.

1982-01-01

Transient emission studies following pulse radiolysis of solid poly(1-vinyl naphthalene) show existence of excited monomers and two excimers. Quenching experiments indicate that excimers are not formed directly by recombination of ions but probably by trapping of migrating monomeric excitation in preformed traps whose density is approximately one in 1000.

Bacterial chemotaxis along vapor-phase gradients of naphthalene.

PubMed

Hanzel, Joanna; Harms, Hauke; Wick, Lukas Y

2010-12-15

The role of bacterial growth and translocation for the bioremediation of organic contaminants in the vadose zone is poorly understood. Whereas air-filled pores restrict the mobility of bacteria, diffusion of volatile organic compounds in air is more efficient than in water. Past research, however, has focused on chemotactic swimming of bacteria along gradients of water-dissolved chemicals. In this study we tested if and to what extent Pseudomonas putida PpG7 (NAH7) chemotactically reacts to vapor-phase gradients forming above their swimming medium by the volatilization from a spot source of solid naphthalene. The development of an aqueous naphthalene gradient by air-water partitioning was largely suppressed by means of activated carbon in the agar. Surprisingly, strain PpG7 was repelled by vapor-phase naphthalene although the steady state gaseous concentrations were 50-100 times lower than the aqueous concentrations that result in positive chemotaxis of the same strain. It is thus assumed that the efficient gas-phase diffusion resulting in a steady, and possibly toxic, naphthalene flux to the cells controlled the chemotactic reaction rather than the concentration to which the cells were exposed. To our knowledge this is the first demonstration of apparent chemotactic behavior of bacteria in response to vapor-phase effector gradients.

21 CFR 172.824 - Sodium mono- and dimethyl naphthalene sulfonates.

Code of Federal Regulations, 2010 CFR

2010-04-01

... SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Multipurpose Additives § 172.824 Sodium mono- and dimethyl naphthalene sulfonates. The food additive sodium mono- and dimethyl naphthalene sulfonates may be safely used in...

Comparative Biochemistry and Metabolism: Part 2. Naphthalene Lung Toxicity

DTIC Science & Technology

1984-10-14

naphthalene, produces a highly selective lesion of the pulmonary bronchiolar epithelium in mice. This lesion appears to depend upon the cytochrome P450...predominating. The rates of metabolism were lower than in rodent lung and there were marked interindividual differences. Pulmonary microsome...54 Effect of Cobalt Protoporphyrin on Naphthalene and 2-Methylnaphthalene-Induced Pulmonary Bronchiolar Necrosis

Sources, concentrations, and risks of naphthalene in indoor and outdoor air.

PubMed

Batterman, S; Chin, J-Y; Jia, C; Godwin, C; Parker, E; Robins, T; Max, P; Lewis, T

2012-08-01

Naphthalene is a ubiquitous pollutant, and very high concentrations are sometimes encountered indoors when this chemical is used as a pest repellent or deodorant. This study describes the distribution and sources of vapor-phase naphthalene concentrations in four communities in southeast Michigan, USA. Outdoors, naphthalene was measured in the communities and at a near-road site. Indoors, naphthalene levels were characterized in 288 suburban and urban homes. The median outdoor concentration was 0.15 μg/m(3), and a modest contribution from rush-hour traffic was noted. The median indoor long-term concentration was 0.89 μg/m(3), but concentrations were extremely skewed and 14% of homes exceeded 3 μg/m(3), the chronic reference concentration for non-cancer effects, 8% exceeded 10 μg/m(3), and levels reached 200 μg/m(3). The typical excess individual lifetime cancer risk was about 10(-4) and reached 10(-2) in some homes. Important sources include naphthalene's use as a pest repellent and deodorant, migration from attached garages and, to lesser extents, cigarette smoke and vehicle emissions. Excessive use as a repellent caused the highest concentrations. Naphthalene presents high risks in a subset of homes, and policies and actions to reduce exposures, for example, sales bans or restrictions, improved labeling, and consumer education, should be considered. Long-term average concentrations of naphthalene in most homes fell into the 0.2-1.7 μg/m(3) range reported as representative in earlier studies. The highly skewed distribution of concentrations results in a subset of homes with elevated concentrations and health risks that greatly exceed US EPA and World Health Organization (WHO) guidelines. The most important indoor source is the use of naphthalene as a pest repellant or deodorant; secondary sources include presence of an attached garage, cigarette smoking, and outdoor sources. House-to-house variation was large, reflecting differences among the residences and

Does a concomitant exposure to lead influence unfavorably the naphthalene subchronic toxicity and toxicokinetics?

PubMed

Katsnelson, Boris A; Minigaliyeva, Ilzira A; Degtyareva, Tamara D; Privalova, Larisa I; Beresneva, Tatyana A

2014-01-01

Rats were given 20 times during 40 d either naphthalene per gavage or the same and lead acetate intraperitoneally in single doses corresponding to 5% of the respective 50% lethal doses. The concomitant exposure to lead not only added some typical indicators of lead toxicity to the moderate naphthalene intoxication picture but also exaggerated some less specific indices for intoxication. However, a number of such indices testified to attenuation of naphthalene's adverse effects under the impact of lead. Lead also lowered urinary excretion of both total and conjugated naphthalene, while the free- to total naphthalene ratio in urine sharply increased. These results corroborate implicitly the initial hypothesis that lead, being an inhibitor of cytochrome P450, hinders phase I of the naphthalene biotransformation and, thus, the formation of derivates which can be more toxic but are capable of entering into reactions of conjugation with resulting detoxication and elimination of naphthalene from the body. © 2013 SETAC.

Characterization of naphthalene degradation by Streptomyces sp. QWE-5 isolated from active sludge.

PubMed

Xu, Peng; Ma, Wencheng; Han, Hongjun; Hou, Baolin; Jia, Shengyong

2014-01-01

A bacterial strain, QWE-5, which utilized naphthalene as its sole carbon and energy source, was isolated and identified as Streptomyces sp. It was a Gram-positive, spore-forming bacterium with a flagellum, with whole, smooth, convex and wet colonies. The optimal temperature and pH for QWE-5 were 35 °C and 7.0, respectively. The QWE-5 strain was capable of completely degrading naphthalene at a concentration as high as 100 mg/L. At initial naphthalene concentrations of 10, 20, 50, 80 and 100 mg/L, complete degradation was achieved within 32, 56, 96, 120 and 144 h, respectively. Kinetics of naphthalene degradation was described using the Andrews equation. The kinetic parameters were as follows: qmax (maximum specific degradation rate) = 1.56 h⁻¹, Ks (half-rate constant) = 60.34 mg/L, and KI (substrate-inhibition constant) = 81.76 mg/L. Metabolic intermediates were identified by gas chromatography and mass spectrometry, allowing a new degradation pathway for naphthalene to be proposed. In this pathway, monooxygenation of naphthalene yielded naphthalen-1-ol. Further degradation by Streptomyces sp. QWE-5 produced acetophenone, followed by adipic acid, which was produced as a combination of decarboxylation and hydroxylation processes.

Sources, Concentrations and Risks of Naphthalene in Indoor and Outdoor Air

PubMed Central

Batterman, Stuart; Chin, Jo-Yu; Jia, Chunrong; Godwin, Christopher; Parker, Edith; Robins, Thomas; Max, Paul; Lewis, Toby

2011-01-01

Naphthalene is a ubiquitous pollutant, and very high concentrations are sometimes encountered indoors when this chemical is used as a pest repellent or deodorant. This study describes the distribution and sources of vapor phase naphthalene concentrations in four communities in southeast Michigan, USA. Outdoors, naphthalene was measured in the communities and at a near-road site. Indoors, naphthalene levels were characterized in 288 suburban and urban homes. The median outdoor concentration was 0.15 µg m−3, and a modest contribution from rush-hour traffic was noted. The median indoor long-term concentration was 0.89 µg m−3, but concentrations were extremely skewed and 14% of homes exceeded 3 µg m−3, the chronic reference concentration for non-cancer effects, 8% exceeded 10 µg m−3, and levels reached 200 µg m−3. The typical individual lifetime cancer risk was about 10−4, and reached 10−2 in some homes. Important sources include naphthalene's use as a pest repellent and deodorant, migration from attached garages, and to lesser extents, cigarette smoke and vehicle emissions. Excessive use as a repellent caused the highest concentrations. Naphthalene presents high risks in a subset of homes, and policies and actions to reduce exposures, e.g., sales bans or restrictions, improved labeling and consumer education, should be considered. PMID:22145682

Solvothermal syntheses, structures, and magnetic properties of three cobalt coordination polymers constructed from naphthalene-1,4-dicarboxylic acid and bis(imidazole) linkers

NASA Astrophysics Data System (ADS)

Dong, Jun-Liang; He, Kun-Huan; Wang, Duo-Zhi; Zhang, Ying-Hui; Wang, Dan-Hong

2018-07-01

Three new Co(II) coordination polymers with formulas of {[Co2(L1)(1,4-NDC)2]·3H2O}n (1), [Co3(L2)2(HCOO)2(1,4-NDC)2]n (2) and [Co2(L2)(μ3-OH)(1,4-NDC)1.5]n (3) (1,4-H2NDC = Naphthalene-1,4-dicarboxylic acid, L1 = di(1H-imidazol-1-yl)methane, L2 = 1,4-di(1H-imidazol-1-yl)benzene) were solvothermal synthesized from 1,4-H2NDC with the aid of three different length-controllable auxiliary ligands and fully characterized. Their structures are determined by single-crystal X-ray diffraction, IR spectra, elemental analysis, powder X-ray diffraction and thermogravimetric analysis. Complexes 1 and 3 display 3D framework structures, corresponding to a 6-connected (412·63) net, a 8-connected (424·5·63) net, respectively. However, it is noteworthy that the complex 1 displays a 2-fold interpenetrating framework structure, complex 3 possesses a self-interpenetrating framework structure. Complex 2 displays 2D 4-connected undulating plane net structure. Moreover, magnetic studies indicate antiferromagnetic interactions between the Co(II) ions in the four complexes.

Determination of fenitrothion in water using a voltammetric sensor based on a polymer-modified glassy carbon electrode.

PubMed

Amare, Meareg; Abicho, Samuel; Admassie, Shimelis

2014-01-01

A glassy carbon electrode (GCE) modified with poly(4-amino-3-hydroxynaphthalene sulfonic acid) (poly-AHNSA) was used for the selective and sensitive determination of fenitrothion (FT) organophosphorus pesticide in water. The electrochemical behavior of FT at the bare GCE and the poly-AHNSA/GCE were compared using cyclic voltammetry. Enhanced peak current response and shift to a lower potential at the polymer-modified electrode indicated the electrocatalytic activity of the polymer film towards FT. Under optimized solution and method parameters, the adsorptive stripping square wave voltammetric reductive peak current of FT was linear to FT concentration in the range of 0.001 to 6.6 x 10(-6) M, and the LOD obtained (3delta/m) was 7.95 x 10(-10) M. Recoveries in the range 96-98% of spiked FT in tap water and reproducible results with RSD of 2.6% (n = 5) were obtained, indicating the potential applicability of the method for the determination of trace levels of FT in environmental samples.

Comparative Biochemistry and Metabolism. Part 2. Naphthalene Lung Toxicity

DTIC Science & Technology

1983-08-01

Amounts of Supernatant Enzyme Protein on the Rates of Formation of a Polar Metabolite and NapY-’ halene - Glutathione Adducts...demonstrating the regio- and stereospecific formation of glutathione adducts from aromatic and aliphatic epoxides (Yagen et al., 1981; Van Bladeren et al...butylated hydroxyanisole, Cancer Res. 41:4309-4315. Bock, K.W., Van Ackeren, G., Lorch, "L., Birke, F., (1976), Metabolism of naphthalene to naphthalene

Cometabolic Degradation of Dibenzofuran and Dibenzothiophene by a Naphthalene-Degrading Comamonas sp. JB.

PubMed

Ji, Xiangyu; Xu, Jing; Ning, Shuxiang; Li, Nan; Tan, Liang; Shi, Shengnan

2017-12-01

Comamonas sp. JB was used to investigate the cometabolic degradation of dibenzofuran (DBF) and dibenzothiophene (DBT) with naphthalene as the primary substrate. Dehydrogenase and ATPase activity of the growing system with the presence of DBF and DBT were decreased when compared to only naphthalene in the growing system, indicating that the presence of DBF and DBT inhibited the metabolic activity of strain JB. The pathways and enzymes involved in the cometabolic degradation were tested. Examination of metabolites elucidated that strain JB cometabolically degraded DBF to 1,2-dihydroxydibenzofuran, subsequently to 2-hydroxy-4-(3'-oxo-3'H-benzofuran-2'-yliden)but-2-enoic acid, and finally to catechol. Meanwhile, strain JB cometabolically degraded DBT to 1,2-dihydroxydibenzothiophene and subsequently to the ring cleavage product. A series of naphthalene-degrading enzymes including naphthalene dioxygenase, 1,2-dihydroxynaphthalene dioxygenase, salicylaldehyde dehydrogenase, salicylate hydroxylase, and catechol 2,3-oxygenase have been detected, confirming that naphthalene was the real inducer of expression the degradation enzymes and metabolic pathways were controlled by naphthalene-degrading enzymes.

Secondary Organic Aerosol Formation from the Photooxidation of Naphthalene

NASA Astrophysics Data System (ADS)

Zhou, S.; Chen, Y.; Wenger, J.

2009-04-01

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous air pollutants that are released into the atmosphere as a by-product of combustion processes. The gas-phase PAHs can be chemically transformed via reaction with the hydroxyl radical to produce a range of oxidised organic compounds and other pollutants such as ozone and secondary organic aerosol (SOA). Epidemiological studies have established that exposure to this type of air pollution is associated with damaging effects on the respiratory and cardiovascular systems, and can lead to asthma, oxidative stress, health deterioration and even death. The major anthropogenic source of SOA in urban areas is believed to be aromatic hydrocarbons, which are present in automobile fuels and are used as solvents. As a result, research is currently being performed on the characterisation of SOA produced from aromatic hydrocarbons such as toluene, the xylenes and trimethylbenzenes. However, significant amounts of PAHs are also released into urban areas from automobile emissions and the combustion of fossil fuels for home heating. Naphthalene is regularly cited as the most abundant PAH in polluted urban air, with typical ambient air concentrations of 0.05 - 0.20 parts per billion (ppbV) in European cities, comparable to the xylenes. Since naphthalene reacts in an analogous manner to monocyclic aromatic compounds then it is also expected to make a significant contribution to ambient SOA. However, the yield and chemical composition of SOA produced from the atmospheric degradation of naphthalene is not well known. In this presentation, the effects of NOx level and relative humidity on the SOA formation from the phootooixdation of naphthalene will be presented. A series of experiments has been performed in a large atmospheric simulation chamber equipped with a gas chromatograph and analyzers for monitoring nitrogen oxides (NOx) and ozone. SOA formation from the photooxidation of naphthalene was measured using a scanning mobility

Effects of secondary carbon supplement on biofilm-mediated biodegradation of naphthalene by mutated naphthalene 1, 2-dioxygenase encoded by Pseudomonas putida strain KD9.

PubMed

Dutta, Kunal; Shityakov, Sergey; Khalifa, Ibrahim; Mal, Arpan; Moulik, Satya Priya; Panda, Amiya Kumar; Ghosh, Chandradipa

2018-05-18

Polycyclic aromatic hydrocarbons (PAHs) belong to a diverse group of environmental pollutants distributed ubiquitously in the environment. The carcinogenic properties of PAHs are the main causes of harm to human health. The green technology, biodegradation have become convenient options to address the environmental pollution. In this study, we analyzed the biodegradation potential of naphthalene with secondary carbon supplements (SCSs) in carbon deficient media (CSM) by Pseudomonas putida strain KD9 isolated from oil refinerary waste. The rigid-flexible molecular docking method revealed that the mutated naphthalene 1,2-dioxygenase had lower affinity for naphthalene than that found in wild type strain. Moreover, analytical methods (HPLC, qRT-PCR) and soft agar chemotaxis suggest sucrose (0.5 wt%) to be the best chemo-attractant and it unequivocally caused enhanced biodegradation of naphthalene (500 mg L -1 ) in both biofilm-mediated and shake-flask biodegradation methods. In addition, the morphological analysis detected from microscopy clearly showed KD9 to change its size and shape (rod to pointed) during biodegradation of naphthalene in CSM as sole source of carbon and energy. The forward versus side light scatter plot of the singlet cells obtained from flow cytometry suggests smaller cell size in CSM and lower florescence intensity of the total DNA content of cells. This study concludes that sucrose may be used as potential bio-stimulation agent. Copyright © 2018 Elsevier B.V. All rights reserved.

Photoinduced Charge Transport Spectra for Porphyrin and Naphthalene Derivative-based Dendrimers

NASA Astrophysics Data System (ADS)

Park, J. H.; Wu, Y.; Parquette, J. R.; Epstein, A. J.

2006-03-01

Dendrimers are important chemical structures for harvesting charge. We prepared model dendrimers using two porphyrin derivatives and a naphthalene derivative. Films of these porphyrin derivatives have a strong Soret band (˜430nm) and four significant Q-bands; the naphthalene derivative has strong absorption at 365 and 383nm. Two kinds of photovoltaic cell structures [ITO/BaytronP/(thick or thin) dendrimer/Al] are constructed to investigate the optical response spectra of dendrimers under electric potential(V) on the cell (range from -1V to 2V). To obtain pure optical responses, incident light is modulated with an optical chopper and a lock-in amplifier is used to measure current (IAC) and phase (θ). For the excitation of the Soret band, IAC and θ do not change substantially with change of sign and amplitude of V. For Q-bands and naphthalene absorption bands, θ nearly follows the polarity of V on the cells and IAC is linear with V. Hence, IAC is nearly ohmic for Q- band although there are shifts due to built-in-potential. IAC for Soret band is almost same for thick and thin active layer cells. In contrast, IAC increases with thickness increase for Q bands. Mechanisms of photogeneration and charge transport will be discussed.

Structure-Property Relationships of Semiconducting Polymers for Flexible and Durable Polymer Field-Effect Transistors.

PubMed

Kim, Min Je; Jung, A-Ra; Lee, Myeongjae; Kim, Dongjin; Ro, Suhee; Jin, Seon-Mi; Nguyen, Hieu Dinh; Yang, Jeehye; Lee, Kyung-Koo; Lee, Eunji; Kang, Moon Sung; Kim, Hyunjung; Choi, Jong-Ho; Kim, BongSoo; Cho, Jeong Ho

2017-11-22

We report high-performance top-gate bottom-contact flexible polymer field-effect transistors (FETs) fabricated by flow-coating diketopyrrolopyrrole (DPP)-based and naphthalene diimide (NDI)-based polymers (P(DPP2DT-T2), P(DPP2DT-TT), P(DPP2DT-DTT), P(NDI2OD-T2), P(NDI2OD-F2T2), and P(NDI2OD-Se2)) as semiconducting channel materials. All of the polymers displayed good FET characteristics with on/off current ratios exceeding 10 7 . The highest hole mobility of 1.51 cm 2 V -1 s -1 and the highest electron mobility of 0.85 cm 2 V -1 s -1 were obtained from the P(DPP2DT-T2) and P(NDI2OD-Se2) polymer FETs, respectively. The impacts of the polymer structures on the FET performance are well-explained by the interplay between the crystallinity, the tendency of the polymer backbone to adopt an edge-on orientation, and the interconnectivity of polymer fibrils in the film state. Additionally, we demonstrated that all of the flexible polymer-based FETs were highly resistant to tensile stress, with negligible changes in their carrier mobilities and on/off ratios after a bending test. Conclusively, these high-performance, flexible, and durable FETs demonstrate the potential of semiconducting conjugated polymers for use in flexible electronic applications.

MEASUREMENT OF HEMOGLOBIN AND ALBUMIN ADDUCTS OF NAPHTHALENE-1,2-OXIDE, 1,2-NAPHTHOQUINONE AND 1,4-NAPHTHOQUINONE AFTER ADMINISTRATION OF NAPHTHALENE TO F344 RATS

EPA Science Inventory

Naphthalene-1,2-oxide (NPO), 1,2-naphthoquinone (1,2-NPQ) and 1,4-naphthoquinone (1,4-NPQ) are the major metabolites of naphthalene that are thought to be responsible for the cytotoxicity and genotoxicity of this chemical. We measured cysteinyl adducts of these metabolites in ...

Mode-of-Action Uncertainty for Dual-Mode Carcinogens:Lower Bounds for Naphthalene-Induced Nasal Tumors in Rats Implied byPBPK and 2-Stage Stochastic Cancer Risk Models

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

Bogen, K T

2007-01-30

As reflected in the 2005 USEPA Guidelines for Cancer Risk Assessment, some chemical carcinogens may have a site-specific mode of action (MOA) that is dual, involving mutation in addition to cell-killing induced hyperplasia. Although genotoxicity may contribute to increased risk at all doses, the Guidelines imply that for dual MOA (DMOA) carcinogens, judgment be used to compare and assess results obtained using separate ''linear'' (genotoxic) vs. ''nonlinear'' (nongenotoxic) approaches to low-level risk extrapolation. However, the Guidelines allow the latter approach to be used only when evidence is sufficient to parameterize a biologically based model that reliably extrapolates risk to lowmore » levels of concern. The Guidelines thus effectively prevent MOA uncertainty from being characterized and addressed when data are insufficient to parameterize such a model, but otherwise clearly support a DMOA. A bounding factor approach--similar to that used in reference dose procedures for classic toxicity endpoints--can address MOA uncertainty in a way that avoids explicit modeling of low-dose risk as a function of administered or internal dose. Even when a ''nonlinear'' toxicokinetic model cannot be fully validated, implications of DMOA uncertainty on low-dose risk may be bounded with reasonable confidence when target tumor types happen to be extremely rare. This concept was illustrated for the rodent carcinogen naphthalene. Bioassay data, supplemental toxicokinetic data, and related physiologically based pharmacokinetic and 2-stage stochastic carcinogenesis modeling results all clearly indicate that naphthalene is a DMOA carcinogen. Plausibility bounds on rat-tumor-type specific DMOA-related uncertainty were obtained using a 2-stage model adapted to reflect the empirical link between genotoxic and cytotoxic effects of the most potent identified genotoxic naphthalene metabolites, 1,2- and 1,4-naphthoquinone. Resulting bounds each provided the basis for a corresponding

Simultaneous Quantification of Multiple Urinary Naphthalene Metabolites by Liquid Chromatography Tandem Mass Spectrometry

PubMed Central

Ayala, Daniel C.; Morin, Dexter; Buckpitt, Alan R.

2015-01-01

Naphthalene is an environmental toxicant to which humans are exposed. Naphthalene causes dose-dependent cytotoxicity to murine airway epithelial cells but a link between exposure and human pulmonary disease has not been established. Naphthalene toxicity in rodents depends on P450 metabolism. Subsequent biotransformation results in urinary elimination of several conjugated metabolites. Glucuronide and sulfate conjugates of naphthols have been used as markers of naphthalene exposure but, as the current studies demonstrate, these assays provide a limited view of the range of metabolites generated from the parent hydrocarbon. Here, we present a liquid chromatography tandem mass spectrometry method for measurement of the glucuronide and sulfate conjugates of 1-naphthol as well as the mercapturic acids and N-acetyl glutathione conjugates from naphthalene epoxide. Standard curves were linear over 2 log orders. On column detection limits varied from 0.91 to 3.4 ng; limits of quantitation from 1.8 to 6.4 ng. The accuracy of measurement of spiked urine standards was -13.1 to + 5.2% of target and intra-day and inter-day variability averaged 7.2 (± 4.5) and 6.8 (± 5.0) %, respectively. Application of the method to urine collected from mice exposed to naphthalene at 15 ppm (4 hrs) showed that glutathione-derived metabolites accounted for 60-70% of the total measured metabolites and sulfate and glucuronide conjugates were eliminated in equal amounts. The method is robust and directly measures several major naphthalene metabolites including those derived from glutathione conjugation of naphthalene epoxide. The assays do not require enzymatic deconjugation, extraction or derivatization thus simplifying sample work up. PMID:25853821

KINETICS OF CHROMATE REDUCTION DURING NAPHTHALENE DEGRADATION IN A MIXED CULTURE

EPA Science Inventory

A mixed culture of Bacillus sp. K1 and Sphingomonas paucimobilis EPA 505 was exposed to chromate and naphthalene. Batch experiments showed that chromate was reduced and naphthalene was degraded by the mixed culture. Chromate reduction occurred initially at a high rate followed by...

[Effects of naphthalene on soil respiration, nutrients and enzyme activities in the subalpine forest of western Sichuan, China].

PubMed

Yang, Fan; Yang, Wan Qin; Wu, Fu Zhong; Wang, Hui; Lan, Li Ying; Liu, Yu Wei; Guo, Cai Hong; Tan, Bo

2017-06-18

As a biocide to reduce soil and litter faunal populations in field experiments, naphthalene has been widely used in the study of ecological functions of soil fauna, but the non-target effects of naphthalene bring about enormous uncertainty to its application. In order to understand whether there were non-target effects of naphthalene in subalpine forest soil, soil in the subalpine forests of west Qinghai-Tibet Plateau was taken as study object. The short-term responses of soil respiration rate, nutrient content and enzyme activity to naphthalene were studied in microcosms. The results showed that soil respiration rate was significantly suppressed by application of naphthalene within 0-10 days, and then showed a significant promotion effect. Naphthalene significantly affected the dynamics of soil NH 4 + -N and NO 3 - -N contents. With application of naphthalene, the highest contents of NH 4 + -N and NO 3 - -N occurred at the 3rd and 7th day, respectively. But they were observed at the 45th and 52nd day with no-naphthalene, respectively. Moreover, soil dissolved carbon content in the naphthalene microcosms showed a sharp increase and then decrease dynamic at the 3rd day, while small change was detected in the no-naphthalene microcosms. Dissolved nitrogen content in both the naphthalene and no-naphthalene microcosms showed an increase at first and then decreased subsequently during the study period. Similar dynamics were found for the soil enzyme activities in both the naphthalene and no-naphthalene microcosms. The highest activities of urease, nitrate reductase and nitrite reductase in both the naphthalene and no-naphthalene microcosms were at the 45th, 38th and 10th day, respectively. In addition, the interaction of naphthalene treatment and sampling time had significant effects on soil respiration rate, the contents of NH 4 + -N, NO 3 - -N and dissolved nitrogen, but had no significant effects on soil dissolved carbon content, and the activities of invertase

[Degradation characteristics of naphthalene with a Pseudomonas aeruginosa strain isolated from soil contaminated by diesel].

PubMed

Liu, Wen-Chao; Wu, Bin-Bin; Li, Xiao-Sen; Lu, Dian-Nan; Liu, Yong-Min

2015-02-01

Abstract: A naphthalene-degrading bacterium (referred as HD-5) was isolated from the diesel-contaminated soil and was assigned to Pseudomonas aeruginosa according to 16S rDNA sequences analysis. Gene nah, which encodes naphthalene dioxygenase, was identified from strain HD-5 by PCR amplification. Different bioremediation approaches, including nature attenuation, bioaugmentation with strain Pseudomonas aeruginosa, biostimulation, and an integrated degradation by bioaugmentation and biostimulation, were evaluated for their effectiveness in the remediating soil containing 5% naphthalene. The degradation rates of naphthalene in the soil were compared among the different bioremediation approaches, the FDA and dehydrogenase activity in bioremediation process were measured, and the gene copy number of 16S rRNA and nah in soil were dynamically monitored using real-time PCR. It was shown that the naphthalene removal rate reached 71.94%, 62.22% and 83.14% in approaches of bioaugmentation (B), biostimulation(S) and integrated degradation composed of bioaugmentation and biostimulation (BS), respectively. The highest removal rate of naphthalene was achieved by using BS protocol, which also gives the highest FDA and dehydrogenase activity. The gene copy number of 16S rRNA and nah in soil increased by about 2.67 x 10(11) g(-1) and 8.67 x 10(8) g(-1) after 31 days treatment using BS protocol. Above-mentioned results also demonstrated that the screened bacterium, Pseudomonas aeruginosa, could grow well in naphthalene-contaminated soil and effectively degrade naphthalene, which is of fundamental importance for bioremediation of naphthalene-contaminated soil.

Simplified MPN method for enumeration of soil naphthalene degraders using gaseous substrate.

PubMed

Wallenius, Kaisa; Lappi, Kaisa; Mikkonen, Anu; Wickström, Annika; Vaalama, Anu; Lehtinen, Taru; Suominen, Leena

2012-02-01

We describe a simplified microplate most-probable-number (MPN) procedure to quantify the bacterial naphthalene degrader population in soil samples. In this method, the sole substrate naphthalene is dosed passively via gaseous phase to liquid medium and the detection of growth is based on the automated measurement of turbidity using an absorbance reader. The performance of the new method was evaluated by comparison with a recently introduced method in which the substrate is dissolved in inert silicone oil and added individually to each well, and the results are scored visually using a respiration indicator dye. Oil-contaminated industrial soil showed slightly but significantly higher MPN estimate with our method than with the reference method. This suggests that gaseous naphthalene was dissolved in an adequate concentration to support the growth of naphthalene degraders without being too toxic. The dosing of substrate via gaseous phase notably reduced the work load and risk of contamination. The result scoring by absorbance measurement was objective and more reliable than measurement with indicator dye, and it also enabled further analysis of cultures. Several bacterial genera were identified by cloning and sequencing of 16S rRNA genes from the MPN wells incubated in the presence of gaseous naphthalene. In addition, the applicability of the simplified MPN method was demonstrated by a significant positive correlation between the level of oil contamination and the number of naphthalene degraders detected in soil.

Polymer modified glassy carbon electrode for the electrochemical determination of caffeine in coffee.

PubMed

Amare, Meareg; Admassie, Shimelis

2012-05-15

4-Amino-3-hydroxynaphthalene sulfonic acid (AHNSA) was electropolymerized on a glassy carbon electrode. The deposited film showed electrocatalytic activity towards the oxidation of caffeine. The polymer-modified electrode showed high sensitivity, selectivity and stability in the determination of caffeine in coffee. The peak current increased linearly with the concentration of caffeine in the range of 6 × 10(-8) to 4 × 10(-5) mol L(-1), with a detection limit of 1.37 × 10(-7) mol L(-1) (LoD = 3δ/slope). Analysis of caffeine in coffee was affected neither by sample matrices nor by structurally similar compounds. Recoveries ranging between 93.75 ± 2.32 and 100.75 ± 3.32 were achieved from coffee extracts indicating the applicability of the developed method for real sample analyses. Copyright © 2012 Elsevier B.V. All rights reserved.

A novel Pseudomonas gessardii strain LZ-E simultaneously degrades naphthalene and reduces hexavalent chromium.

PubMed

Huang, Haiying; Wu, Kejia; Khan, Aman; Jiang, Yiming; Ling, Zhenmin; Liu, Pu; Chen, Yong; Tao, Xuanyu; Li, Xiangkai

2016-05-01

Combined pollutants with polycyclic aromatic hydrocarbons (PAHs) and heavy metals have been identified as toxic and unmanageable contaminates. In this work, Pseudomonas gessardii strain LZ-E isolated from wastewater discharge site of a petrochemical company degrades naphthalene and reduces Cr(VI) simultaneously. 95% of 10mgL(-1) Cr(VI) was reduced to Cr(III) while 77% of 800mgL(-1) naphthalene was degraded when strain LZ-E was incubated in BH medium for 48h. Furthermore, naphthalene promotes Cr(VI) reduction in strain LZ-E as catechol and phthalic acid produced in naphthalene degradation are able to reduce Cr(VI) abiotically. An aerated bioreactor system was setup to test strain LZ-E's remediation ability. Strain LZ-E continuously remediated naphthalene and Cr(VI) at rates of 15mgL(-1)h(-1) and 0.20mgL(-1)h(-1) of 800mgL(-1) naphthalene and 10mgL(-1) Cr(VI) addition with eight batches in 16days. In summary, strain LZ-E is a potential applicant for combined pollution remediation. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

All-Polymer Solar Cell Performance Optimized via Systematic Molecular Weight Tuning of Both Donor and Acceptor Polymers.

PubMed

Zhou, Nanjia; Dudnik, Alexander S; Li, Ting I N G; Manley, Eric F; Aldrich, Thomas J; Guo, Peijun; Liao, Hsueh-Chung; Chen, Zhihua; Chen, Lin X; Chang, Robert P H; Facchetti, Antonio; Olvera de la Cruz, Monica; Marks, Tobin J

2016-02-03

The influence of the number-average molecular weight (Mn) on the blend film morphology and photovoltaic performance of all-polymer solar cells (APSCs) fabricated with the donor polymer poly[5-(2-hexyldodecyl)-1,3-thieno[3,4-c]pyrrole-4,6-dione-alt-5,5-(2,5-bis(3-dodecylthiophen-2-yl)thiophene)] (PTPD3T) and acceptor polymer poly{[N,N'-bis(2-octyldodecyl)naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} (P(NDI2OD-T2); N2200) is systematically investigated. The Mn effect analysis of both PTPD3T and N2200 is enabled by implementing a polymerization strategy which produces conjugated polymers with tunable Mns. Experimental and coarse-grain modeling results reveal that systematic Mn variation greatly influences both intrachain and interchain interactions and ultimately the degree of phase separation and morphology evolution. Specifically, increasing Mn for both polymers shrinks blend film domain sizes and enhances donor-acceptor polymer-polymer interfacial areas, affording increased short-circuit current densities (Jsc). However, the greater disorder and intermixed feature proliferation accompanying increasing Mn promotes charge carrier recombination, reducing cell fill factors (FF). The optimized photoactive layers exhibit well-balanced exciton dissociation and charge transport characteristics, ultimately providing solar cells with a 2-fold PCE enhancement versus devices with nonoptimal Mns. Overall, it is shown that proper and precise tuning of both donor and acceptor polymer Mns is critical for optimizing APSC performance. In contrast to reports where maximum power conversion efficiencies (PCEs) are achieved for the highest Mns, the present two-dimensional Mn optimization matrix strategy locates a PCE "sweet spot" at intermediate Mns of both donor and acceptor polymers. This study provides synthetic methodologies to predictably access conjugated polymers with desired Mn and highlights the importance of optimizing Mn for both polymer

All-Polymer Solar Cell Performance Optimized via Systematic Molecular Weight Tuning of Both Donor and Acceptor Polymers

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

Zhou, Nanjia; Dudnik, Alexander S.; Li, Ting I. N. G.

2015-12-31

ABSTRACT: The influence of the number-average molecular weight (Mn) on the blend film morphology and photovoltaic performance of all-polymer solar cells (APSCs) fabricated with the donor polymer poly[5-(2-hexyldodecyl)-1,3-thieno[3,4- c]pyrrole-4,6-dione-alt-5,5-(2,5-bis(3-dodecylthiophen-2-yl)- thiophene)] (PTPD3T) and acceptor polymer poly{[N,N'- bis(2-octyldodecyl)naphthalene-1,4,5,8-bis(dicarboximide)- 2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} (P(NDI2OD-T2); N2200) is systematically investigated. The M n effect analysis of both PTPD3T and N2200 is enabled by implementing a polymerization strategy which produces conjugated polymers with tunable M ns. Experimental and coarse-grain modeling results reveal that systematic M n variation greatly influences both intrachain and interchain interactions and ultimately the degree of phase separation and morphology evolution. Specifically, increasing M n formore » both polymers shrinks blend film domain sizes and enhances donor-acceptor polymer-polymer interfacial areas, affording increased short-circuit current densities (J sc). However, the greater disorder and intermixed feature proliferation accompanying increasing M n promotes charge carrier recombination, reducing cell fill factors (FF). The optimized photoactive layers exhibit well-balanced exciton dissociation and charge transport characteristics, ultimately providing solar cells with a 2-fold PCE enhancement versus devices with nonoptimal M ns. Overall, it is shown that proper and precise tuning of both donor and acceptor polymer M ns is critical for optimizing APSC performance. In contrast to reports where maximum power conversion efficiencies (PCEs) are achieved for the highest M ns, the present two-dimensional M n optimization matrix strategy locates a PCE “sweet spot” at intermediate Mns of both donor and acceptor polymers. This study provides synthetic methodologies to predictably access conjugated polymers with desired M n and highlights the importance of

Differentiation of naphthalene and paradichlorobenzene mothballs based on their difference in specific gravity.

PubMed

Fukuda, T; Koyama, K; Yamashita, M; Koichi, N; Takeda, M

1991-08-01

The present study was conducted to measure the specific gravities of paradichlorobenzene and naphthalene mothballs and compare them with the specific gravity of a saturated aqueous solution of sodium chloride (1.197). The specific gravities of 450 paradichlorobenzene mothballs from 5 manufactures and 150 naphthalene mothballs from 2 manufactures were measured with a specific gravity meter. The mean specific gravities of paradichlorobenzene mothballs were between 1.429 and 1.437 (p = 0.99). On the other hand, the mean specific gravities of naphthalene mothballs were between 1.094 and 1.100 (p = 0.99). Based on the fact that paradichlorobenzene mothballs sink in a saturated solution of salt whereas naphthalene mothballs float on it, these 2 kinds of mothballs ought to be rapidly and accurately distinguished in clinical settings.

Interrelation of nonequivalent Csbnd C bonds of naphthalene frame and spatial orientation of substituents: Beta-naphthalene sulfonyl fluoride and beta-naphthalene sulfonyl chloride

NASA Astrophysics Data System (ADS)

Giricheva, Nina I.; Petrov, Vjacheslav M.; Oberhammer, Heinz; Petrova, Valentina N.; Dakkouri, Marwan; Ivanov, Sergey N.; Girichev, Georgiy V.

2013-06-01

β-naphthalene sulfonyl fluoride, β-NaphSF, and β-naphthalene sulfonyl chloride, β-NaphSCl, were studied by gas-phase electron diffraction (GED) and quantum chemical calculations (B3LYP and MP2 in combination with cc-pVDZ, aug-cc-pVDZ and cc-pVTZ basis sets). For each compound the calculations predicted the existence of two conformers which are enantiomers. On the basis of the experimental data it was found that the gas phase over β-NaphSF and NaphSCl at 357(5) K and 395(5) K, respectively, consists of molecular species of C1 symmetry in which the Cβsbnd Ssbnd Hal plane deviates from the perpendicular orientation relative to the naphthalene skeleton plane. The following geometrical parameters (Å and degrees) were obtained from the experiment (uncertainties are in parentheses): rh1(Csbnd H)aver. = 1.097(7), rh1(Csbnd C)aver. = 1.410(3), rh1(Csbnd S) = 1.753(6), rh1(Ssbnd O)aver. = 1.414(4), rh1(Ssbnd F) = 1.559(5), ∠Csbnd Cβsbnd C = 122.8(3), ∠Cβsbnd Ssbnd F = 103.3(30); Φ(Cαsbnd Cβsbnd Ssbnd F) = 104(6) for β-NaphSF, and rh1(Csbnd H)aver. = 1.089(4), rh1(Csbnd C)aver. = 1.411(3), rh1(Csbnd S) = 1.757(5), rh1(Ssbnd O)aver. = 1.419(3), rh1(Ssbnd Сl) = 2.053(4), ∠Csbnd Cβsbnd C = 122.8(1), ∠Cβsbnd Ssbnd Cl = 102.2(7), Φ(Cαsbnd Cβsbnd Ssbnd Cl) = 108(3) for β-NaphSCl. The calculated barriers to internal rotation of the sulfonyl halide groups exceed considerably the thermal energy values corresponding to the temperatures of the GED experiments. Natural bond orbital (NBO) analyses of the electron density distribution were applied to explain the peculiarities of the molecular structure of the studied compounds and the deviation from the structures of their benzene analogs.

Enrichment and characterization of sulfate reducing, naphthalene degrading microorganisms

NASA Astrophysics Data System (ADS)

Steffen, Kümmel; Florian-Alexander, Herbst; Márcia, Duarte; Dietmar, Pieper; Jana, Seifert; Bergen Martin, von; Hans-Hermann, Richnow; Carsten, Vogt

2014-05-01

Polycyclic aromatic hydrocarbons (PAH) are pollutants of great concern due to their potential toxicity, mutagenicity and carcinogenicity. PAH are widely distributed in the environment by accidental discharges during the transport, use and disposal of petroleum products, and during forest and grass fires. Caused by their hydrophobic nature, PAH basically accumulate in sediments from where they are slowly released into the groundwater. Although generally limited by the low water solubility of PAH, microbial degradation is one of the major mechanisms leading to the complete clean-up of PAH-contaminated sites. Whereas organisms and biochemical pathways responsible for the aerobic breakdown of PAH are well known, anaerobic PAH biodegradation is less understood; only a few anaerobic PAH degrading cultures have been described. We studied the anaerobic PAH degradation in a microcosm approach to enrich anaerobic PAH degraders. Anoxic groundwater and sediment samples were used as inoculum. Groundwater samples were purchased from the erstwhile gas works facility and a former wood impregnation site. In contrast, sources of sediment samples were a former coal refining area and an old fuel depot. Samples were incubated in anoxic mineral salt medium with naphthalene as sole carbon source and sulfate as terminal electron acceptor. Grown cultures were characterized by feeding with 13C-labeled naphthalene, 16S rRNA gene sequencing using an Illumina® approach, and functional proteome analyses. Finally, six enrichment cultures able to degrade naphthalene under anoxic conditions were established. First results point to a dominance of identified sequences affiliated to the freshwater sulfate-reducing strain N47, which is a known anaerobic naphthalene degrader, in four out of the six enrichments. In those enrichments, peptides related to the pathway of anoxic naphthalene degradation in N47 were abundant. Overall the data underlines the importance of Desulfobacteria for natural

All-Polymer Solar Cell Performance Optimized via Systematic Molecular Weight Tuning of Both Donor and Acceptor Polymers

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

Zhou, Nanjia; Dudnik, Alexander S.; Li, Ting I. N. G.

2016-01-21

The influence of the number-average molecular weight (Mn) on the blend film morphology and photovoltaic performance of all-polymer solar cells (APSCs) fabricated with the donor polymer poly[5-(2-hexyldodecyl)-1,3-thieno[3,4-c]pyrrole-4,6-dione-alt-5,5-(2,5-bis(3-dodecylthiophen-2-yl)thiophene)] (PTPD3T) and acceptor polymer poly{[N,N'-bis(2-octyldodecyl)naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} (P(NDI2OD-T2); N2200) is systematically investigated. The Mn effect analysis of both PTPD3T and N2200 is enabled by implementing a polymerization strategy which produces conjugated polymers with tunable Mns. Experimental and coarse-grain modeling results reveal that systematic Mn variation greatly influences both intrachain and interchain interactions and ultimately the degree of phase separation and morphology evolution. Specifically, increasing Mn for both polymers shrinks blend film domain sizes and enhancesmore » donor–acceptor polymer–polymer interfacial areas, affording increased short-circuit current densities (Jsc). However, the greater disorder and intermixed feature proliferation accompanying increasing Mn promotes charge carrier recombination, reducing cell fill factors (FF). The optimized photoactive layers exhibit well-balanced exciton dissociation and charge transport characteristics, ultimately providing solar cells with a 2-fold PCE enhancement versus devices with nonoptimal Mns. Overall, it is shown that proper and precise tuning of both donor and acceptor polymer Mns is critical for optimizing APSC performance. In contrast to reports where maximum power conversion efficiencies (PCEs) are achieved for the highest Mns, the present two-dimensional Mn optimization matrix strategy locates a PCE “sweet spot” at intermediate Mns of both donor and acceptor polymers. This study provides synthetic methodologies to predictably access conjugated polymers with desired Mn and highlights the importance of optimizing Mn for

Hypothesis-based weight-of-evidence evaluation and risk assessment for naphthalene carcinogenesis

PubMed Central

Bailey, Lisa A.; Nascarella, Marc A.; Kerper, Laura E.; Rhomberg, Lorenz R.

2016-01-01

Inhalation of naphthalene causes olfactory epithelial nasal tumors in rats (but not in mice) and benign lung adenomas in mice (but not in rats). The limited available human data have not identified an association between naphthalene exposure and increased respiratory cancer risk. Assessing naphthalene's carcinogenicity in humans, therefore, depends entirely on experimental evidence from rodents. We evaluated the respiratory carcinogenicity of naphthalene in rodents, and its potential relevance to humans, using our Hypothesis-Based Weight-of-Evidence (HBWoE) approach. We systematically and comparatively reviewed data relevant to key elements in the hypothesized modes of action (MoA) to determine which is best supported by the available data, allowing all of the data from each realm of investigation to inform interpretation of one another. Our analysis supports a mechanism that involves initial metabolism of naphthalene to the epoxide, followed by GSH depletion, cytotoxicity, chronic inflammation, regenerative hyperplasia, and tumor formation, with possible weak genotoxicity from downstream metabolites occurring only at high cytotoxic doses, strongly supporting a non-mutagenic threshold MoA in the rat nose. We also conducted a dose–response analysis, based on the likely MoA, which suggests that the rat nasal MoA is not relevant in human respiratory tissues at typical environmental exposures. Our analysis illustrates how a thorough WoE evaluation can be used to support a MoA, even when a mechanism of action cannot be fully elucidated. A non-mutagenic threshold MoA for naphthalene-induced rat nasal tumors should be considered as a basis to determine human relevance and to guide regulatory and risk-management decisions. PMID:26202831

Considerations of the Effects of Naphthalene Moieties on the Design of Proton-Conductive Poly(arylene ether ketone) Membranes for Direct Methanol Fuel Cells.

PubMed

Wang, Baolong; Hong, Lihua; Li, Yunfeng; Zhao, Liang; Wei, Yuxue; Zhao, Chengji; Na, Hui

2016-09-14

Novel sulfonated poly(arylene ether ketones) (SDN-PAEK-x), consisting of dual naphthalene and flexible sulfoalkyl groups, were prepared via polycondensation, demethylation, and sulfobutylation grafting reaction. Among them, SDN-PAEK-1.94 membrane with the highest ion exchange capacity (IEC = 2.46 mequiv·g(-1)) exhibited the highest proton conductivity, which was 0.147 S· cm(-1) at 25 °C and 0.271 S·cm(-1) at 80 °C, respectively. The introduction of dual naphthalene moieties is expected to achieve much enhanced properties compared to those of sulfonated poly(arylene ether ketones) (SNPAEK-x), consisting of single naphthalene and flexible sulfoalkyl groups. Compared with SNPAEK-1.60 with a similar IEC, SDN-PAEK-1.74 membrane showed higher proton conductivity, higher IEC normalized conductivity, and higher effective proton mobility, although it had lower analytical acid concentration. The SDN-PAEK-x membranes with IECs higher than 1.96 mequiv·g(-1) also exhibited higher proton conductivity than that of recast Nafion membrane. Furthermore, SDN-PAEK-1.94 displayed a better single cell performance with a maximum power density of 60 mW·cm(-2) at 80 °C. Considering its high proton conductivity, excellent single cell performance, good mechanical stabilities, low membrane swelling, and methanol permeability, SDN-PAEK-x membranes are promising candidates as alternative polymer electrolyte membranes to Nafion for direct methanol fuel cell applications.

STABILITY OF HEMOGLOBIN AND ALBUMIN ADDUCTS OF NAPHTHALENE OXIDE, 1,2-NAPHTHOQUINONE, AND 1,4-NAPHTHOQUINONE

EPA Science Inventory

Naphthalene is an important industrial chemical, which has recently been shown to cause tumors of the respiratory tract in rodents. It is thought that one or more reactive metabolites of naphthalene, namely, naphthalene-1,2-oxide (NPO), 1,2-naphthoquinone (1,2-NPQ), and 1,4-na...

Biodegradation of naphthalene and anthracene by chemo-tactically active rhizobacteria of populus deltoides

PubMed Central

Bisht, Sandeep; Pandey, Piyush; Sood, Anchal; Sharma, Shivesh; Bisht, N. S.

2010-01-01

Several naphthalene and anthracene degrading bacteria were isolated from rhizosphere of Populus deltoides, which were growing in non-contaminated soil. Among these, four isolates, i.e. Kurthia sp., Micrococcus varians, Deinococcus radiodurans and Bacillus circulans utilized chrysene, benzene, toluene and xylene, in addition to anthracene and naphthalene. Kurthia sp and B. circulans showed positive chemotactic response for naphthalene and anthracene. The mean growth rate constant (K) of isolates were found to increase with successive increase in substrate concentration (0.5 to 1.0 mg/50ml). B. circulans SBA12 and Kurthia SBA4 degraded 87.5% and 86.6% of anthracene while, Kurthia sp. SBA4, B. circulans SBA12, and M. varians SBA8 degraded 85.3 %, 95.8 % and 86.8 % of naphthalene respectively after 6 days of incubation as determined by HPLC analysis. PMID:24031572

Quantifying the Effect of Polymer Blending through Molecular Modelling of Cyanurate Polymers

PubMed Central

Crawford, Alasdair O.; Hamerton, Ian; Cavalli, Gabriel; Howlin, Brendan J.

2012-01-01

Modification of polymer properties by blending is a common practice in the polymer industry. We report here a study of blends of cyanurate polymers by molecular modelling that shows that the final experimentally determined properties can be predicted from first principles modelling to a good degree of accuracy. There is always a compromise between simulation length, accuracy and speed of prediction. A comparison of simulation times shows that 125ps of molecular dynamics simulation at each temperature provides the optimum compromise for models of this size with current technology. This study opens up the possibility of computer aided design of polymer blends with desired physical and mechanical properties. PMID:22970230

Alkylation effects on the energy transfer of highly vibrationally excited naphthalene.

PubMed

Hsu, Hsu Chen; Tsai, Ming-Tsang; Dyakov, Yuri A; Ni, Chi-Kung

2011-11-04

The energy transfer of highly vibrationally excited isomers of dimethylnaphthalene and 2-ethylnaphthalene in collisions with krypton were investigated using crossed molecular beam/time-of-flight mass spectrometer/time-sliced velocity map ion imaging techniques at a collision energy of approximately 300 cm(-1). Angular-resolved energy-transfer distribution functions were obtained directly from the images of inelastic scattering. The results show that alkyl-substituted naphthalenes transfer more vibrational energy to translational energy than unsubstituted naphthalene. Alkylation enhances the V→T energy transfer in the range -ΔE(d)=-100~-1500 cm(-1) by approximately a factor of 2. However, the maximum values of V→T energy transfer for alkyl-substituted naphthalenes are about 1500~2000 cm(-1), which is similar to that of naphthalene. The lack of rotation-like wide-angle motion of the aromatic ring and no enhancement in very large V→T energy transfer, like supercollisions, indicates that very large V→T energy transfer requires special vibrational motions. This transfer cannot be achieved by the low-frequency vibrational motions of alkyl groups. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Constitutive modeling of glassy shape memory polymers

NASA Astrophysics Data System (ADS)

Khanolkar, Mahesh

The aim of this research is to develop constitutive models for non-linear materials. Here, issues related for developing constitutive model for glassy shape memory polymers are addressed in detail. Shape memory polymers are novel material that can be easily formed into complex shapes, retaining memory of their original shape even after undergoing large deformations. The temporary shape is stable and return to the original shape is triggered by a suitable mechanism such heating the polymer above a transition temperature. Glassy shape memory polymers are called glassy because the temporary shape is fixed by the formation of a glassy solid, while return to the original shape is due to the melting of this glassy phase. The constitutive model has been developed to capture the thermo-mechanical behavior of glassy shape memory polymers using elements of nonlinear mechanics and polymer physics. The key feature of this framework is that a body can exist stress free in numerous natural configurations, the underlying natural configuration of the body changing during the process, with the response of the body being elastic from these evolving natural configurations. The aim of this research is to formulate a constitutive model for glassy shape memory polymers (GSMP) which takes in to account the fact that the stress-strain response depends on thermal expansion of polymers. The model developed is for the original amorphous phase, the temporary glassy phase and transition between these phases. The glass transition process has been modeled using a framework that was developed recently for studying crystallization in polymers and is based on the theory of multiple natural configurations. Using the same frame work, the melting of the glassy phase to capture the return of the polymer to its original shape is also modeled. The effect of nanoreinforcement on the response of shape memory polymers (GSMP) is studied and a model is developed. In addition to modeling and solving boundary

Naphthalene SOA: redox activity and naphthoquinone gas-particle partitioning

NASA Astrophysics Data System (ADS)

McWhinney, R. D.; Zhou, S.; Abbatt, J. P. D.

2013-10-01

Chamber secondary organic aerosol (SOA) from low-NOx photooxidation of naphthalene by hydroxyl radical was examined with respect to its redox cycling behaviour using the dithiothreitol (DTT) assay. Naphthalene SOA was highly redox-active, consuming DTT at an average rate of 118 ± 14 pmol per minute per μg of SOA material. Measured particle-phase masses of the major previously identified redox active products, 1,2- and 1,4-naphthoquinone, accounted for only 21 ± 3% of the observed redox cycling activity. The redox-active 5-hydroxy-1,4-naphthoquinone was identified as a new minor product of naphthalene oxidation, and including this species in redox activity predictions increased the predicted DTT reactivity to 30 ± 5% of observations. These results suggest that there are substantial unidentified redox-active SOA constituents beyond the small quinones that may be important toxic components of these particles. A gas-to-SOA particle partitioning coefficient was calculated to be (7.0 ± 2.5) × 10-4 m3 μg-1 for 1,4-naphthoquinone at 25 °C. This value suggests that under typical warm conditions, 1,4-naphthoquinone is unlikely to contribute strongly to redox behaviour of ambient particles, although further work is needed to determine the potential impact under conditions such as low temperatures where partitioning to the particle is more favourable. Also, higher order oxidation products that likely account for a substantial fraction of the redox cycling capability of the naphthalene SOA are likely to partition much more strongly to the particle phase.

Urinary and breast milk biomarkers to assess exposure to naphthalene in pregnant women: an investigation of personal and indoor air sources

PubMed Central

2014-01-01

Background Naphthalene exposures for most non-occupationally exposed individuals occur primarily indoors at home. Residential indoor sources include pest control products (specifically moth balls), incomplete combustion such as cigarette smoke, woodstoves and cooking, some consumer and building products, and emissions from gasoline sources found in attached garages. The study aim was to assess naphthalene exposure in pregnant women from Canada, using air measurements and biomarkers of exposure. Methods Pregnant women residing in Ottawa, Ontario completed personal and indoor air sampling, and questionnaires. During pregnancy, pooled urine voids were collected over two 24-hour periods on a weekday and a weekend day. At 2–3 months post-birth, they provided a spot urine sample and a breast milk sample following the 24-hour air monitoring. Urines were analyzed for 1-naphthol and 2-naphthol and breast milk for naphthalene. Simple linear regression models examined associations between known naphthalene sources, air and biomarker samples. Results Study recruitment rate was 11.2% resulting in 80 eligible women being included. Weekday and weekend samples were highly correlated for both personal (r = 0.83, p < 0.0001) and indoor air naphthalene (r = 0.91, p < 0.0001). Urine specific gravity (SG)-adjusted 2-naphthol concentrations collected on weekdays and weekends (r = 0.78, p < 0.001), and between pregnancy and postpartum samples (r = 0.54, p < 0.001) were correlated. Indoor and personal air naphthalene concentrations were significantly higher post-birth than during pregnancy (p < 0.0001 for signed rank tests); concurrent urine samples were not significantly different. Naphthalene in breast milk was associated with urinary 1-naphthol: a 10% increase in 1-naphthol was associated with a 1.6% increase in breast milk naphthalene (95% CI: 0.2%-3.1%). No significant associations were observed between naphthalene sources reported in self

Naphthalene, an insect repellent, is produced by Muscodor vitigenus, a novel endophytic fungus

Treesearch

Bryn H. Daisy; Gary A. Strobel; Uvidelio Castillo; David Ezra; Joe Sears; David K. Weaver; Justin B. Runyon

2002-01-01

Muscodor vitigenus is a recently described endophytic fungus of Paullinia paullinioides, a liana growing in the understorey of the rainforests of the Peruvian Amazon. This fungus produces naphthalene under certain cultural conditions. Naphthalene produced by M. vitigenus was identified by gas chromatography/mass...

A Thermal Dehydrogenative Diels–Alder Reaction of Styrenes for the Concise Synthesis of Functionalized Naphthalenes

PubMed Central

Kocsis, Laura S.; Benedetti, Erica

2012-01-01

Functionalized naphthalenes are valuable building blocks in many important areas. A microwave-assisted, intramolecular dehydrogenative Diels-Alder reaction of styrenyl derivatives to provide cyclopenta[b]naphthalene substructures not previously accessible using existing synthetic methods is described. The synthetic utility of these uniquely functionalized naphthalenes was demonstrated by a single-step conversion of one of these cycloadducts to a fluorophore bearing a structural resemblance to Prodan. PMID:22913473

A thermal dehydrogenative Diels-Alder reaction of styrenes for the concise synthesis of functionalized naphthalenes.

PubMed

Kocsis, Laura S; Benedetti, Erica; Brummond, Kay M

2012-09-07

Functionalized naphthalenes are valuable building blocks in many important areas. A microwave-assisted, intramolecular dehydrogenative Diels-Alder reaction of styrenyl derivatives to provide cyclopenta[b]naphthalene substructures not previously accessible using existing synthetic methods is described. The synthetic utility of these uniquely functionalized naphthalenes was demonstrated by a single-step conversion of one of these cycloadducts to a fluorophore bearing a structural resemblance to Prodan.

Constitutive Modeling of Nanotube-Reinforced Polymer Composites

NASA Technical Reports Server (NTRS)

Odegard, G. M.; Gates, T. S.; Wise, K. E.; Park, C.; Siochi, E. J.; Bushnell, Dennis M. (Technical Monitor)

2002-01-01

In this study, a technique is presented for developing constitutive models for polymer composite systems reinforced with single-walled carbon nanotubes (SWNT). Because the polymer molecules are on the same size scale as the nanotubes, the interaction at the polymer/nanotube interface is highly dependent on the local molecular structure and bonding. At these small length scales, the lattice structures of the nanotube and polymer chains cannot be considered continuous, and the bulk mechanical properties can no longer be determined through traditional micromechanical approaches that are formulated by using continuum mechanics. It is proposed herein that the nanotube, the local polymer near the nanotube, and the nanotube/polymer interface can be modeled as an effective continuum fiber using an equivalent-continuum modeling method. The effective fiber serves as a means for incorporating micromechanical analyses for the prediction of bulk mechanical properties of SWNT/polymer composites with various nanotube lengths, concentrations, and orientations. As an example, the proposed approach is used for the constitutive modeling of two SWNT/polyimide composite systems.

3-{[(E)-(2-Hydroxynaphthalen-1-yl)methylidene]amino}pyridinium per­chlorate

PubMed Central

Damous, Maamar; Dénès, George; Bouacida, Sofiane; Hamlaoui, Meriem; Merazig, Hocine; Daran, Jean-Claude

2013-01-01

In the title Schiff base salt, C16H13N2O+·ClO4 −, the pyridine ring and the naphthalene ring system are approximately co-planar [making a dihedral angle of 6.05 (12)°] and an intra­molecular O—H⋯N hydrogen bond occurs between the hydroxyl and imino groups. In the crystal, the cations and anions are linked by N—H⋯O and weak C—H⋯O hydrogen bonds, forming the supra­molecular layers parallel to (100). The crystal studied was an inversion twin refined with minor component = 0.43 (13). PMID:24427084

Benzene and naphthalene in air and breath as indicators of exposure to jet fuel

PubMed Central

Egeghy, P; Hauf-Cabalo, L; Gibson, R; Rappaport, S

2003-01-01

Aims: To estimate exposures to benzene and naphthalene among military personnel working with jet fuel (JP-8) and to determine whether naphthalene might serve as a surrogate for JP-8 in studies of health effects. Methods: Benzene and naphthalene were measured in air and breath of 326 personnel in the US Air Force, who had been assigned a priori into low, moderate, and high exposure categories for JP-8. Results: Median air concentrations for persons in the low, moderate, and high exposure categories were 3.1, 7.4, and 252 µg benzene/m3 air, 4.6, 9.0, and 11.4 µg benzene/m3 breath, 1.9, 10.3, and 485 µg naphthalene/m3 air, and 0.73, 0.93, and 1.83 µg naphthalene/m3 breath, respectively. In the moderate and high exposure categories, 5% and 15% of the benzene air concentrations, respectively, were above the 2002 threshold limit value (TLV) of 1.6 mg/m3. Multiple regression analyses of air and breath levels revealed prominent background sources of benzene exposure, including cigarette smoke. However, naphthalene exposure was not unduly influenced by sources other than JP-8. Among heavily exposed workers, dermal contact with JP-8 contributed to air and breath concentrations along with several physical and environmental factors. Conclusions: Personnel having regular contact with JP-8 are occasionally exposed to benzene at levels above the current TLV. Among heavily exposed workers, uptake of JP-8 components occurs via both inhalation and dermal contact. Naphthalene in air and breath can serve as useful measures of exposure to JP-8 and uptake of fuel components in the body. PMID:14634191

Dye-Incorporated Polynaphthalenediimide Acceptor for Additive-Free High-Performance All-Polymer Solar Cells.

PubMed

Chen, Dong; Yao, Jia; Chen, Lie; Yin, Jingping; Lv, Ruizhi; Huang, Bin; Liu, Siqi; Zhang, Zhi-Guo; Yang, Chunhe; Chen, Yiwang; Li, Yongfang

2018-04-16

All-polymer solar cells (all-PSCs) can offer unique advantages for applications in flexible devices, and naphthalene diimide (NDI)-based polymer acceptors are the widely used polymer acceptors. However, their power conversion efficiency (PCE) still lags behind that of state-of-the-art polymer solar cells, due to low light absorption, suboptimal energy levels and the strong aggregation of the NDI-based polymer acceptor. Herein, a rhodanine-based dye molecule was introduced into the NDI-based polymer acceptor by simple random copolymerization and showed an improved light absorption coefficient, an up-shifted lowest unoccupied molecular orbital level and reduced crystallization. Consequently, additive-free all-PSCs demonstrated a high PCE of 8.13 %, which is one of the highest performance characteristics reported for all-PSCs to date. These results indicate that incorporating a dye into the n-type polymer gives insight into the precise design of high-performance polymer acceptors for all-PSCs. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Properties of maize stalk biochar produced under different pyrolysis temperatures and its sorption capability to naphthalene].

PubMed

Huang, Hua; Wang, Ya-Xiong; Tang, Jing-Chun; Tang, Jing-Chun; Zhu, Wen-Ying

2014-05-01

Biochar was made from maize stalk under three different temperatures of 300, 500 and 700 degreeC. The elemental composition of biochar was measured by elemental analyzer. Scanning electron microscope (SEM) was used to measure the surface morphology. Sorption of naphthalene to biochar was researched by batch sorption experiments. Results showed that, with the increase of temperature, C content increased from 66. 79% to 76. 30% , H and O contents decreased from 4.92% and 19. 25% to 3. 18% and 9.53%, respectively; H/C, O/C, (O + N)/C, aromaticity and hydrophobicity increased, and polarity decreased. SEM results showed that maize stalk biochar was platy particles, and its roughness of surface increased with increasing temperature. The sorption of naphthalene on biochar followed the Lagergren pseudo-second order dynamic sorption model. Initial sorption rate and equilibrium sorption capacity increased as preparation temperatures increased at the same initial concentration of naphthalene. The isotherm sorption behavior can be described by the Freundlich model, which indicated that, as pyrolysis temperature increased, the sorption capacity of biochar increased, and nonlinearity increased first and then decreased. Biochar derived from maize stalk had distinct features when compared with other feedstocks, and its elemental composition, surface features and sorption behaviors were significantly influenced by pyrolysis temperature.

Model systems for single molecule polymer dynamics

PubMed Central

Latinwo, Folarin

2012-01-01

Double stranded DNA (dsDNA) has long served as a model system for single molecule polymer dynamics. However, dsDNA is a semiflexible polymer, and the structural rigidity of the DNA double helix gives rise to local molecular properties and chain dynamics that differ from flexible chains, including synthetic organic polymers. Recently, we developed single stranded DNA (ssDNA) as a new model system for single molecule studies of flexible polymer chains. In this work, we discuss model polymer systems in the context of “ideal” and “real” chain behavior considering thermal blobs, tension blobs, hydrodynamic drag and force–extension relations. In addition, we present monomer aspect ratio as a key parameter describing chain conformation and dynamics, and we derive dynamical scaling relations in terms of this molecular-level parameter. We show that asymmetric Kuhn segments can suppress monomer–monomer interactions, thereby altering global chain dynamics. Finally, we discuss ssDNA in the context of a new model system for single molecule polymer dynamics. Overall, we anticipate that future single polymer studies of flexible chains will reveal new insight into the dynamic behavior of “real” polymers, which will highlight the importance of molecular individualism and the prevalence of non-linear phenomena. PMID:22956980

Squamocin, an annonaceous acetogenin, enhances naphthalene degradation mediated by Bacillus atrophaeus CN4.

PubMed

Parellada, Eduardo A; Igarza, Mercedes; Isacc, Paula; Bardón, Alicia; Ferrero, Marcela; Ameta, Keshav Lalit; Neske, Adriana

Squamocin belongs to a group of compounds called annonaceous acetogenins. They are secondary products of Annonaceae metabolism and can be isolated from Annona cherimolia seeds. This paper deals with the stimulation of biofilm formation of Bacillus atrophaeus CN4 by employing low squamocin concentrations to increase naphthalene degradation. Bacillus atrophaeus CN4, isolated from contaminated soil, has the ability to degrade naphthalene as the only source of carbon and energy. In the absence of additional carbon sources, the strain removed 69% of the initial concentration of naphthalene (approx. 0.2mmol/l) in the first 12h of incubation. The addition of squamocin in LB medium stimulated Bacillus atrophaeus CN4 biofilm formation and enhanced naphthalene removal. Squamocin (2.5μg/ml) does not affect planktonic growth and therefore, the observed increases are solely due to the stimulation of biofilm formation. Copyright © 2017 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

Energy transfer of highly vibrationally excited naphthalene: collisions with CHF3, CF4, and Kr.

PubMed

Chen Hsu, Hsu; Tsai, Ming-Tsang; Dyakov, Yuri A; Ni, Chi-Kung

2011-08-07

Energy transfer of highly vibrationally excited naphthalene in the triplet state in collisions with CHF(3), CF(4), and Kr was studied using a crossed-beam apparatus along with time-sliced velocity map ion imaging techniques. Highly vibrationally excited naphthalene (2.0 eV vibrational energy) was formed via the rapid intersystem crossing of naphthalene initially excited to the S(2) state by 266 nm photons. The shapes of the collisional energy-transfer probability density functions were measured directly from the scattering results of highly vibrationally excited naphthalene. In comparison to Kr atoms, the energy transfer in collisions between CHF(3) and naphthalene shows more forward scatterings, larger cross section for vibrational to translational (V → T) energy transfer, smaller cross section for translational to vibrational and rotational (T → VR) energy transfer, and more energy transferred from vibration to translation, especially in the range -ΔE(d) = -100 to -800 cm(-1). On the other hand, the difference of energy transfer properties between collisional partners Kr and CF(4) is small. The enhancement of the V → T energy transfer in collisions with CHF(3) is attributed to the large attractive interaction between naphthalene and CHF(3) (1-3 kcal/mol).

Infrared spectroscopy of hydrated naphthalene cluster anions.

PubMed

Knurr, Benjamin J; Adams, Christopher L; Weber, J Mathias

2012-09-14

We present infrared spectra of mass-selected C(10)H(8)(-)·(H(2)O)(n)·Ar(m) cluster anions (n = 1-6) obtained by Ar predissociation spectroscopy. The experimental spectra are compared with predicted spectra from density functional theory calculations. The OH groups of the water ligands are involved in H-bonds to other water molecules or to the π system of the naphthalene anion, which accommodates the excess electron. The interactions in the water network are generally found to be more important than those between water molecules and the ion. For 2 ≤ n ≤ 4 the water molecules form single layer water networks on one side of the naphthalene anion, while for n = 5 and 6, cage and multilayer structures become more energetically favorable. For cluster sizes with more than 3 water molecules, multiple conformers are likely to be responsible for the experimental spectra.

Oxidation of Naphthenoaromatic and Methyl-Substituted Aromatic Compounds by Naphthalene 1,2-Dioxygenase

PubMed Central

Selifonov, S. A.; Grifoll, M.; Eaton, R. W.; Chapman, P. J.

1996-01-01

Oxidation of acenaphthene, acenaphthylene, and fluorene was examined with recombinant strain Pseudomonas aeruginosa PAO1(pRE695) expressing naphthalene dioxygenase genes cloned from plasmid NAH7. Acenaphthene underwent monooxygenation to 1-acenaphthenol with subsequent conversion to 1-acenaphthenone and cis- and trans-acenaphthene-1,2-diols, while acenaphthylene was dioxygenated to give cis-acenaphthene-1,2-diol. Nonspecific dehydrogenase activities present in the host strain led to the conversion of both of the acenaphthene-1,2-diols to 1,2-acenaphthoquinone. The latter was oxidized spontaneously to naphthalene-1,8-dicarboxylic acid. No aromatic ring dioxygenation products were detected from acenaphthene and acenaphthylene. Mixed monooxygenase and dioxygenase actions of naphthalene dioxygenase on fluorene yielded products of benzylic 9-monooxygenation, aromatic ring dioxygenation, or both. The action of naphthalene dioxygenase on a variety of methyl-substituted aromatic compounds, including 1,2,4-trimethylbenzene and isomers of dimethylnaphthalene, resulted in the formation of benzylic alcohols, i.e., methyl group monooxygenation products, which were subsequently converted to the corresponding carboxylic acids by dehydrogenase(s) in the host strain. Benzylic monooxygenation of methyl groups was strongly predominant over aromatic ring dioxygenation and essentially nonspecific with respect to the substitution pattern of the aromatic substrates. In addition to monooxygenating benzylic methyl and methylene groups, naphthalene dioxygenase behaved as a sulfoxygenase, catalyzing monooxygenation of the sulfur heteroatom of 3-methylbenzothiophene. PMID:16535238

Naphthalene and benzene degradation under Fe(III)-reducing conditions in petroleum-contaminated aquifers

USGS Publications Warehouse

Anderson, Robert T.; Lovely, Derek R.

1999-01-01

Naphthalene was oxidized anaerobically to CO2 in sediments collected from a petroleum-contaminated aquifer in Bemidji, Minnesota in which Fe(III) reduction was the terminal electron-accepting process. Naphthalene was not oxidized in sediments from the methanogenic zone at Bemidji or in sediments from the Fe(III)-reducing zone of other petroleum-contaminated aquifers studied. In a profile across the Fe(III)-reducing zone of the Bemidji aquifer, rates of naphthalene oxidation were fastest in sediments with the highest proportion of Fe(III), which was also the zone of the most rapid degradation of benzene, toluene, and acetate. The comparative studies attempted to elucidate factors that might account for the fact that unsubstituted aromatic hydrocarbons such as benzene and naphthalene were degraded under Fe(III)-reducing conditions at Bemidji, but not at the other aquifers examined. These studies indicated that the ability of Fe(III)-reducing microorganisms to degrade benzene and naphthalene at the Bemidji site cannot be attributed to groundwater components that make Fe(III) more available for reduction or other potential factors that were evaluated. However, unlike the other aquifers evaluated, uncontaminated sediments at the Bemidji site could be adapted for anaerobic benzene degradation merely with the addition of benzene. These findings indicate that Bemidji sediments naturally contain Fe(III) reducers capable of degradation of unsubstituted aromatic hydrocarbons.

40 CFR 721.10045 - Diazotized substituted heteromonocycle coupled with naphthalene sulfonic acid derivative, nickel...

Code of Federal Regulations, 2014 CFR

2014-07-01

... coupled with naphthalene sulfonic acid derivative, nickel complex, alkaline salt (generic). 721.10045... derivative, nickel complex, alkaline salt (generic). (a) Chemical substance and significant new uses subject... heteromonocycle coupled with naphthalene sulfonic acid derivative, nickel complex, alkaline salt (PMN P-02-737) is...

40 CFR 721.10045 - Diazotized substituted heteromonocycle coupled with naphthalene sulfonic acid derivative, nickel...

Code of Federal Regulations, 2011 CFR

2011-07-01

... coupled with naphthalene sulfonic acid derivative, nickel complex, alkaline salt (generic). 721.10045... derivative, nickel complex, alkaline salt (generic). (a) Chemical substance and significant new uses subject... heteromonocycle coupled with naphthalene sulfonic acid derivative, nickel complex, alkaline salt (PMN P-02-737) is...

40 CFR 721.10045 - Diazotized substituted heteromonocycle coupled with naphthalene sulfonic acid derivative, nickel...

Code of Federal Regulations, 2013 CFR

2013-07-01

... coupled with naphthalene sulfonic acid derivative, nickel complex, alkaline salt (generic). 721.10045... derivative, nickel complex, alkaline salt (generic). (a) Chemical substance and significant new uses subject... heteromonocycle coupled with naphthalene sulfonic acid derivative, nickel complex, alkaline salt (PMN P-02-737) is...

40 CFR 721.10045 - Diazotized substituted heteromonocycle coupled with naphthalene sulfonic acid derivative, nickel...

Code of Federal Regulations, 2010 CFR

2010-07-01

... coupled with naphthalene sulfonic acid derivative, nickel complex, alkaline salt (generic). 721.10045... derivative, nickel complex, alkaline salt (generic). (a) Chemical substance and significant new uses subject... heteromonocycle coupled with naphthalene sulfonic acid derivative, nickel complex, alkaline salt (PMN P-02-737) is...

40 CFR 721.10045 - Diazotized substituted heteromonocycle coupled with naphthalene sulfonic acid derivative, nickel...

Code of Federal Regulations, 2012 CFR

2012-07-01

... coupled with naphthalene sulfonic acid derivative, nickel complex, alkaline salt (generic). 721.10045... derivative, nickel complex, alkaline salt (generic). (a) Chemical substance and significant new uses subject... heteromonocycle coupled with naphthalene sulfonic acid derivative, nickel complex, alkaline salt (PMN P-02-737) is...

Native Fluorescence Detection Methods and Detectors for Naphthalene and/or Other Volatile Organic Compound Vapors

NASA Technical Reports Server (NTRS)

Hug, William F. (Inventor); Bhartia, Rohit (Inventor); Reid, Ray D. (Inventor); Lane, Arthur L. (Inventor)

2014-01-01

Naphthalene, benzene, toluene, xylene, and other volatile organic compounds have been identified as serious health hazards. This is especially true for personnel working with JP8 jet fuel and other fuels containing naphthalene as well as other hazardous volatile organic compounds (VOCs). Embodiments of the invention are directed to methods and apparatus for near-real-time in-situ detection and accumulated dose measurement of exposure to naphthalene vapor and other hazardous gaseous VOCs. The methods and apparatus employ excitation of fluorophors native or endogenous to compounds of interest using light sources emitting in the ultraviolet below 300 nm and measurement of native fluorescence emissions in distinct wavebands above the excitation wavelength. The apparatus of some embodiments are cell-phone-sized sensor/dosimeter "badges" to be worn by personnel potentially exposed to naphthalene or other hazardous VOCs. The badge sensor of some embodiments provides both real time detection and data logging of exposure to naphthalene or other VOCs of interest from which both instantaneous and accumulated dose can be determined. The badges employ a new native fluorescence based detection method to identify and differentiate VOCs. The particular focus of some embodiments are the detection and identification of naphthalene while other embodiments are directed to detection and identification of other VOCs like aromatic hydrocarbons such as benzene, toluene, and xylene.

Constitutive Modeling of Nanotube-Reinforced Polymer Composites

NASA Technical Reports Server (NTRS)

Odegard, G. M.; Gates, T. S.; Wise, K. E.

2002-01-01

In this study, a technique is presented for developing constitutive models for polymer composite systems reinforced with single-walled carbon nanotubes (SWNT). Because the polymer molecules are on the same size scale as the nanotubes, the interaction at the polymer/nanotube interface is highly dependent on the local molecular structure and bonding. At these small length scales, the lattice structures of the nanotube and polymer chains cannot be considered continuous, and the bulk mechanical properties can no longer be determined through traditional micromechanical approaches that are formulated by using continuum mechanics. It is proposed herein that the nanotube, the local polymer near the nanotube, and the nanotube/polymer interface can be modeled as an effective continuum fiber using an equivalent-continuum modeling method. The effective fiber serves as a means for incorporating micromechanical analyses for the prediction of bulk mechanical properties of SWNT/polymer composites with various nanotube shapes, sizes, concentrations, and orientations. As an example, the proposed approach is used for the constitutive modeling of two SWNT/LaRC-SI (with a PmPV interface) composite systems, one with aligned SWNTs and the other with three-dimensionally randomly oriented SWNTs. The Young's modulus and shear modulus have been calculated for the two systems for various nanotube lengths and volume fractions.

Conformationally constrained farnesoid X receptor (FXR) agonists: heteroaryl replacements of the naphthalene.

PubMed

Bass, Jonathan Y; Caravella, Justin A; Chen, Lihong; Creech, Katrina L; Deaton, David N; Madauss, Kevin P; Marr, Harry B; McFadyen, Robert B; Miller, Aaron B; Mills, Wendy Y; Navas, Frank; Parks, Derek J; Smalley, Terrence L; Spearing, Paul K; Todd, Dan; Williams, Shawn P; Wisely, G Bruce

2011-02-15

To improve on the drug properties of GSK8062 1b, a series of heteroaryl bicyclic naphthalene replacements were prepared. The quinoline 1c was an equipotent FXR agonist with improved drug developability parameters relative to 1b. In addition, analog 1c lowered body weight gain and serum glucose in a DIO mouse model of diabetes. Copyright © 2010 Elsevier Ltd. All rights reserved.

Constitutive Modeling of Nanotube-Reinforced Polymer Composite Systems

NASA Technical Reports Server (NTRS)

Odegard, Gregory M.; Harik, Vasyl M.; Wise, Kristopher E.; Gates, Thomas S.

2004-01-01

In this study, a technique has been proposed for developing constitutive models for polymer composite systems reinforced with single-walled carbon nanotubes (SWNT). Since the polymer molecules are on the same size scale as the nanotubes, the interaction at the polymer/nanotube interface is highly dependent on the local molecular structure and bonding. At these small length scales, the lattice structures of the nanotube and polymer chains cannot be considered continuous, and the bulk mechanical properties of the SWNT/polymer composites can no longer be determined through traditional micromechanical approaches that are formulated using continuum mechanics. It is proposed herein that the nanotube, the local polymer near the nanotube, and the nanotube/polymer interface can be modeled as an effective continuum fiber using an equivalent-continuum modeling method. The effective fiber retains the local molecular structure and bonding information and serves as a means for incorporating micromechanical analyses for the prediction of bulk mechanical properties of SWNT/polymer composites with various nanotube sizes and orientations. As an example, the proposed approach is used for the constitutive modeling of two SWNT/polyethylene composite systems, one with continuous and aligned SWNT and the other with discontinuous and randomly aligned nanotubes.

Constitutive Modeling of Nanotube-Reinforced Polymer Composite Systems

NASA Technical Reports Server (NTRS)

Odegard, Gregory M.; Harik, Vasyl M.; Wise, Kristopher E.; Gates, Thomas S.

2001-01-01

In this study, a technique has been proposed for developing constitutive models for polymer composite systems reinforced with single-walled carbon nanotubes (SWNT). Since the polymer molecules are on the same size scale as the nanotubes, the interaction at the polymer/nanotube interface is highly dependent on the local molecular structure and bonding. At these small length scales, the lattice structures of the nanotube and polymer chains cannot be considered continuous, and the bulk mechanical properties of the SWNT/polymer composites can no longer be determined through traditional micromechanical approaches that are formulated using continuum mechanics. It is proposed herein that the nanotube, the local polymer near the nanotube, and the nanotube/polymer interface can be modeled as an effective continuum fiber using an equivalent-continuum modeling method. The effective fiber retains the local molecular structure and bonding information and serves as a means for incorporating micromechanical analyses for the prediction of bulk mechanical properties of SWNT/polymer composites with various nanotube sizes and orientations. As an example, the proposed approach is used for the constitutive modeling of two SWNT/polyethylene composite systems, one with continuous and aligned SWNT and the other with discontinuous and randomly aligned nanotubes.

Benzene and Naphthalene Degrading Bacterial Communities in an Oil Sands Tailings Pond

PubMed Central

Rochman, Fauziah F.; Sheremet, Andriy; Tamas, Ivica; Saidi-Mehrabad, Alireza; Kim, Joong-Jae; Dong, Xiaoli; Sensen, Christoph W.; Gieg, Lisa M.; Dunfield, Peter F.

2017-01-01

Oil sands process-affected water (OSPW), produced by surface-mining of oil sands in Canada, is alkaline and contains high concentrations of salts, metals, naphthenic acids, and polycyclic aromatic compounds (PAHs). Residual hydrocarbon biodegradation occurs naturally, but little is known about the hydrocarbon-degrading microbial communities present in OSPW. In this study, aerobic oxidation of benzene and naphthalene in the surface layer of an oil sands tailings pond were measured. The potential oxidation rates were 4.3 μmol L−1 OSPW d−1 for benzene and 21.4 μmol L−1 OSPW d−1 for naphthalene. To identify benzene and naphthalene-degrading microbial communities, metagenomics was combined with stable isotope probing (SIP), high-throughput sequencing of 16S rRNA gene amplicons, and isolation of microbial strains. SIP using 13C-benzene and 13C-naphthalene detected strains of the genera Methyloversatilis and Zavarzinia as the main benzene degraders, while strains belonging to the family Chromatiaceae and the genus Thauera were the main naphthalene degraders. Metagenomic analysis revealed a diversity of genes encoding oxygenases active against aromatic compounds. Although these genes apparently belonged to many phylogenetically diverse taxa, only a few of these taxa were predominant in the SIP experiments. This suggested that many members of the community are adapted to consuming other aromatic compounds, or are active only under specific conditions. 16S rRNA gene sequence datasets have been submitted to the Sequence Read Archive (SRA) under accession number SRP109130. The Gold Study and Project submission ID number in Joint Genome Institute IMG/M for the metagenome is Gs0047444 and Gp0055765. PMID:29033909

Transcriptional responses in the rat nasal epithelium following subchronic inhalation of naphthalene vapor

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

Clewell, H.J., E-mail: hclewell@thehamner.org; Efremenko, A.; Campbell, J.L.

.9 ppm, respectively. Using a published physiologically based pharmacokinetic (PBPK) model to estimate target tissue dose relevant to the proposed mode of action (total naphthalene metabolism per gram nasal tissue), the lowest transcriptional BMDLs from this analysis equate to human continuous naphthalene exposure at approximately 0.3 ppm. It is unlikely that significant effects of naphthalene or its metabolites will occur at exposures below this concentration. - Highlights: • We investigated mode of action for carcinogenicity of inhaled naphthalene in rats. • Gene expression changes were measured in rat nasal tissues after 90 day exposures. • Support a non-linear mode of action (oxidative stress, inflammation, and proliferation) • Suggest a dose-dependent transition in the mode of action between 1.0 and 10 ppm • Transcriptional benchmark doses could inform point of departure for risk assessment.« less

Naphthalene emissions from moth repellents or toilet deodorant blocks determined using head-space and small-chamber tests.

PubMed

Jo, Wan-Kuen; Lee, Jong-Hyo; Lim, Ho-Jin; Jeong, Woo-Sik

2008-01-01

The present study investigated the emissions of naphthalene and other compounds from several different moth repellents (MRs) and one toilet deodorant block (TDB) currently sold in Korea, using a headspace analysis. The emission factors and emission rates of naphthalene were studied using a small-scale environmental chamber. Paper-type products emitted a higher concentration of the total volatile organic compounds (VOCs) (normalized to the weight of test piece) than ball-type products, which in turn emitted higher concentration than a gel-type product. In contrast, naphthalene was either the most or the second highest abundant compound for the four ball products, whereas for paper and gel products it was not detected or was detected at much lower levels. The abundance of naphthalene ranged between 18.4% and 37.3% for ball products. The results showed that the lower the air changes per hour (ACH) level was, the higher the naphthalene concentrations became. In general, a low ACH level suggests a low ventilation rate. The emission factor for naphthalene was nearly 100 times higher for a ball MR than for a gel or a paper MR. For the ball MR, the lower ACH level resulted in higher emission rate.

Changes in oxygen consumption and respiratory enzymes as stress indicators in an estuarine edible crab Scylla serrata exposed to naphthalene.

PubMed

Vijayavel, K; Balasubramanian, M P

2006-06-01

The sublethal effect of naphthalene was studied on the physiology of a mud crab Scylla serrata. The 96 h acute toxicity of naphthalene was determined and found to be 28 mg 1(-1) (LC100), 18 mg 1(-1) (LC50), 10 mg 1(-1) (LC0) respectively. The 30 days sublethal effect (LC0) 9 mg 1(-1), 8 mg 1(-1), 10 mg 1(-1), of naphthalene was investigated in the crab S. serrata with reference to oxygen consumption and changes in the activity of respiratory enzymes. The results indicated that naphthalene caused disturbance in the normal physiology of the crab. The bioaccumulation of naphthalene was also investigated in gills, hepatopancreas, haemolymph and ovary. The consumption of oxygen increased in the naphthalene medium when compared with that of the crabs exposed to naphthalene free medium. A decreased trend in the activity of respiratory enzymes such as lactate dehydrogenase (LDH), isocitrate dehydrogenase (ICDH), succinate dehydrogenase (SDH), malate dehydrogenase (MDH), alpha-ketoglutarate dehydrogenase (alpha-KDH) and glutathione (GSH) were recorded in the hepatopancreas, ovary and gills of S. serrata for all the tested concentrations of naphthalene and the results were analyzed for their significance.

Complete Genome Sequence of the Naphthalene-Degrading Bacterium Pseudomonas stutzeri AN10 (CCUG 29243)

PubMed Central

Brunet-Galmés, Isabel; Busquets, Antonio; Peña, Arantxa; Gomila, Margarita; Nogales, Balbina; García-Valdés, Elena; Lalucat, Jorge; Bennasar, Antonio

2012-01-01

Pseudomonas stutzeri AN10 (CCUG 29243) can be considered a model strain for aerobic naphthalene degradation. We report the complete genome sequence of this bacterium. Its 4.71-Mb chromosome provides insights into other biodegradative capabilities of strain AN10 (i.e., benzoate catabolism) and suggests a high number of horizontal gene transfer events. PMID:23144395

Measurement of Biologically Available Naphthalene in Gas and Aqueous Phases by Use of a Pseudomonas putida Biosensor

PubMed Central

Werlen, Christoph; Jaspers, Marco C. M.; van der Meer, Jan Roelof

2004-01-01

Genetically constructed microbial biosensors for measuring organic pollutants are mostly applied in aqueous samples. Unfortunately, the detection limit of most biosensors is insufficient to detect pollutants at low but environmentally relevant concentrations. However, organic pollutants with low levels of water solubility often have significant gas-water partitioning coefficients, which in principle makes it possible to measure such compounds in the gas rather than the aqueous phase. Here we describe the first use of a microbial biosensor for measuring organic pollutants directly in the gas phase. For this purpose, we reconstructed a bioluminescent Pseudomonas putida naphthalene biosensor strain to carry the NAH7 plasmid and a chromosomally inserted gene fusion between the sal promoter and the luxAB genes. Specific calibration studies were performed with suspended and filter-immobilized biosensor cells, in aqueous solution and in the gas phase. Gas phase measurements with filter-immobilized biosensor cells in closed flasks, with a naphthalene-contaminated aqueous phase, showed that the biosensor cells can measure naphthalene effectively. The biosensor cells on the filter responded with increasing light output proportional to the naphthalene concentration added to the water phase, even though only a small proportion of the naphthalene was present in the gas phase. In fact, the biosensor cells could concentrate a larger proportion of naphthalene through the gas phase than in the aqueous suspension, probably due to faster transport of naphthalene to the cells in the gas phase. This led to a 10-fold lower detectable aqueous naphthalene concentration (50 nM instead of 0.5 μM). Thus, the use of bacterial biosensors for measuring organic pollutants in the gas phase is a valid method for increasing the sensitivity of these valuable biological devices. PMID:14711624

Adsorption of naphthalene and ozone on atmospheric air/ice interfaces coated with surfactants: a molecular simulation study.

PubMed

Liyana-Arachchi, Thilanga P; Valsaraj, Kalliat T; Hung, Francisco R

2012-03-15

The adsorption of gas-phase naphthalene and ozone molecules onto air/ice interfaces coated with different surfactant species (1-octanol, 1-hexadecanol, or 1-octanal) was investigated using classical molecular dynamics (MD) simulations. Naphthalene and ozone exhibit a strong preference to be adsorbed at the surfactant-coated air/ice interfaces, as opposed to either being dissolved into the bulk of the quasi-liquid layer (QLL) or being incorporated into the ice crystals. The QLL becomes thinner when the air/ice interface is coated with surfactant molecules. The adsorption of both naphthalene and ozone onto surfactant-coated air/ice interfaces is enhanced when compared to bare air/ice interface. Both naphthalene and ozone tend to stay dissolved in the surfactant layer and close to the QLL, rather than adsorbing on top of the surfactant molecules and close to the air region of our systems. Surfactants prefer to orient at a tilted angle with respect to the air/ice interface; the angular distribution and the most preferred angle vary depending on the hydrophilic end group, the length of the hydrophobic tail, and the surfactant concentration at the air/ice interface. Naphthalene prefers to have a flat orientation on the surfactant coated air/ice interface, except at high concentrations of 1-hexadecanol at the air/ice interface; the angular distribution of naphthalene depends on the specific surfactant and its concentration at the air/ice interface. The dynamics of naphthalene molecules at the surfactant-coated air/ice interface slow down as compared to those observed at bare air/ice interfaces. The presence of surfactants does not seem to affect the self-association of naphthalene molecules at the air/ice interface, at least for the specific surfactants and the range of concentrations considered in this study.

[Characteristics of natural strains of naphthalene-utilizing bacteria of the genus Pseudomonas].

PubMed

Levchuk, A A; Vasilenko, S L; Bulyga, I M; Titok, M A; Thomas, K M

2005-01-01

Sixty-three strains of bacteria capable of utilizing naphthalene as the sole source of carbon and energy were isolated from 137 samples of soil taken in different sites in Belarus. All isolated bacteria contained extrachromosomal genetic elements of 45 to 150 kb in length. It was found that bacteria of 31 strains contained the IncP-9 incompatibility group plasmids, bacteria of one strain carried a plasmid containing replicons IncP-9 and IncP-7, and bacteria of 31 strains contained unidentified plasmids. Primary identification showed that the hosts of plasmids of naphthalene biodegradation are fluorescent bacteria of the genus Pseudomonas (P. putida and P. aeruginosa; a total of 47 strains) and unidentified nonfluorescent microorganisms (a total of 16 strains). In addition to the ability to utilize naphthalene, some strains exhibited the ability to stimulate the growth and development of the root system of Secale cereale.

Desaturation, dioxygenation, and monooxygenation reactions catalyzed by naphthalene dioxygenase from Pseudomonas sp. strain 9816-4.

PubMed

Gibson, D T; Resnick, S M; Lee, K; Brand, J M; Torok, D S; Wackett, L P; Schocken, M J; Haigler, B E

1995-05-01

The stereospecific oxidation of indan and indene was examined with mutant and recombinant strains expressing naphthalene dioxygenase of Pseudomonas sp. strain 9816-4. Pseudomonas sp. strain 9816/11 and Escherichia coli JM109(DE3)[pDTG141] oxidized indan to (+)-(1S)-indanol, (+)-cis-(1R,2S)-indandiol, (+)-(1S)-indenol, and 1-indanone. The same strains oxidized indene to (+)-cis-(1R,2S)-indandiol and (+)-(1S)-indenol. Purified naphthalene dioxygenase oxidized indan to the same four products formed by strains 9816/11 and JM109(DE3)[pDTG141]. In addition, indene was identified as an intermediate in indan oxidation. The major products formed from indene by purified naphthalene dioxygenase were (+)-(1S)-indenol and (+)-(1R,2S)-indandiol. The results show that naphthalene dioxygenase catalyzes the enantiospecific monooxygenation of indan to (+)-(1S)-indanol and the desaturation of indan to indene, which then serves as a substrate for the formation of (+)-(1R,2S)-indandiol and (+)-(1S)-indenol. The relationship of the desaturase, monooxygenase, and dioxygenase activities of naphthalene dioxygenase is discussed with reference to reactions catalyzed by toluene dioxygenase, plant desaturases, cytochrome P-450, methane monooxygenase, and other bacterial monooxygenases.

Desaturation, dioxygenation, and monooxygenation reactions catalyzed by naphthalene dioxygenase from Pseudomonas sp. strain 9816-4.

PubMed Central

Gibson, D T; Resnick, S M; Lee, K; Brand, J M; Torok, D S; Wackett, L P; Schocken, M J; Haigler, B E

1995-01-01

The stereospecific oxidation of indan and indene was examined with mutant and recombinant strains expressing naphthalene dioxygenase of Pseudomonas sp. strain 9816-4. Pseudomonas sp. strain 9816/11 and Escherichia coli JM109(DE3)[pDTG141] oxidized indan to (+)-(1S)-indanol, (+)-cis-(1R,2S)-indandiol, (+)-(1S)-indenol, and 1-indanone. The same strains oxidized indene to (+)-cis-(1R,2S)-indandiol and (+)-(1S)-indenol. Purified naphthalene dioxygenase oxidized indan to the same four products formed by strains 9816/11 and JM109(DE3)[pDTG141]. In addition, indene was identified as an intermediate in indan oxidation. The major products formed from indene by purified naphthalene dioxygenase were (+)-(1S)-indenol and (+)-(1R,2S)-indandiol. The results show that naphthalene dioxygenase catalyzes the enantiospecific monooxygenation of indan to (+)-(1S)-indanol and the desaturation of indan to indene, which then serves as a substrate for the formation of (+)-(1R,2S)-indandiol and (+)-(1S)-indenol. The relationship of the desaturase, monooxygenase, and dioxygenase activities of naphthalene dioxygenase is discussed with reference to reactions catalyzed by toluene dioxygenase, plant desaturases, cytochrome P-450, methane monooxygenase, and other bacterial monooxygenases. PMID:7751268

Comparative Metabolism of Hydrazine and Naphthalene.

DTIC Science & Technology

1980-09-01

compounds and chemicals like those in cigarette smoke. Another question of considerable importance to the Air Force is whether animal species currently...the pulmonary cytochrome P-450 monooxygenases differ between species or that enzymes responsible for the detoxification of the "toxic" metabolite(s...metabolic steps in the activation and detoxification of a compound like naphthalene are undertaken in animal lung tissue so that such processes can be

The disposition and metabolism of naphthalene in rats.

PubMed

Kilanowicz, A; Czerski, B; Sapota, A

1999-01-01

The aim of this study was to investigate the distribution, excretion and metabolism of naphthalene-[ring-U-3H] in rats. The experiments were performed on 54 male outbred IMP: Wist rats with body weight of 200-220 g. The compound was administered intraperitoneally in olive oil in a single dose of 20 mg/kg (about 540 kBq per animal). 3H radioactivity was traced in selected organs and tissues, blood, urine and faeces, 1-72 h following the administration. The main metabolites were isolated from urine and identified by the GC-MS method. Urine and faeces proved to be the main route of tritium elimination. Over 88% of the compound was excreted during the first 72 hours. Maximum level of tritium in plasma was observed at the 2nd h after administration following a biphasic decline. Half-lifes for phases I and II were 0.8 and 99 h, respectively. In erythrocytes 3H-decline was monophasic with the half-life of about 9 h. In organs and tissues, the highest concentrations during the first hours after administration were detected in the fat, liver and kidneys. Then, gradual decline of tritium was noticed in all examined tissues. In urine of rats the following substances were identified: (1) naphthalene, (2) 1-naphthol, (3) 2-naphthol, (4) 1,2-naphthalenediol-1,2-dihydro, (5) methylthionaphthalenes (two isomers). In conclusion, naphthalene has a relatively rapid turnover rate in the rat organism and does not form considerable deposits in the tissue. The metabolism encompasses ring hydroxylation, hydration and glutathione conjugation.

Naphthalene degradation by bacterial consortium (DV-AL) developed from Alang-Sosiya ship breaking yard, Gujarat, India.

PubMed

Patel, Vilas; Jain, Siddharth; Madamwar, Datta

2012-03-01

Naphthalene degrading bacterial consortium (DV-AL) was developed by enrichment culture technique from sediment collected from the Alang-Sosiya ship breaking yard, Gujarat, India. The 16S rRNA gene based molecular analyzes revealed that the bacterial consortium (DV-AL) consisted of four strains namely, Achromobacter sp. BAB239, Pseudomonas sp. DV-AL2, Enterobacter sp. BAB240 and Pseudomonas sp. BAB241. Consortium DV-AL was able to degrade 1000 ppm of naphthalene in Bushnell Haas medium (BHM) containing peptone (0.1%) as co-substrate with an initial pH of 8.0 at 37°C under shaking conditions (150 rpm) within 24h. Maximum growth rate and naphthalene degradation rate were found to be 0.0389 h(-1) and 80 mg h(-1), respectively. Consortium DV-AL was able to utilize other aromatic and aliphatic hydrocarbons such as benzene, phenol, carbazole, petroleum oil, diesel fuel, and phenanthrene and 2-methyl naphthalene as sole carbon source. Consortium DV-AL was also efficient to degrade naphthalene in the presence of other pollutants such as petroleum hydrocarbons and heavy metals. Copyright © 2011 Elsevier Ltd. All rights reserved.

Pressure-dependent rate constants for PAH growth: formation of indene and its conversion to naphthalene

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

Mebel, Alexander M.; Georgievskii, Yuri; Jasper, Ahren W.

2016-01-01

Unraveling the mechanisms for growth of polycyclic aromatic hydrocarbons (PAHs) requires accurate temperature- and pressure-dependent rate coefficients for a great variety of feasible pathways. Even the pathways for the formation of the simplest PAHs, indene and naphthalene, are fairly complex. These pathways provide important prototypes for modeling larger PAH growth. In this work we employ the ab initio RRKM theory-based master equation approach to predict the rate constants involved in the formation of indene and its conversion to naphthalene. The reactions eventually leading to indene involve C9Hx (x = 8–11) potential energy surfaces (PESs) and include C6H5 + C3H4 (allenemore » and propyne), C6H6 + C3H3, benzyl + C2H2, C6H5 + C3H6, C6H6 + C3H5 and C6H5 + C3H5. These predictions allow us to make a number of valuable observations on the role of various mechanisms. For instance, we demonstrate that reactions which can significantly contribute to the formation of indene include phenyl + allene and H-assisted isomerization to indene of its major product, 3-phenylpropyne, benzyl + acetylene, and the reactions of the phenyl radical with propene and the allyl radical, both proceeding via the 3-phenylpropene intermediate. 3-Phenylpropene can be activated to a 1-phenylallyl radical, which in turn rapidly decomposes to indene. Next, indene can be converted to benzofulvene or naphthalene under typical combustion conditions, via its activation by H atom abstraction and methyl substitution on the five-membered ring followed by isomerization and decomposition of the resulting 1-methylindenyl radical, C10H9 → C10H8 + H. Alternatively, the same region of the C10H9 PES can be accessed through the reaction of benzyl with propargyl, C7H7 + C3H3 → C10H10 → C10H9 + H, which therefore can also contribute to the formation of benzofulvene or naphthalene. Benzofulvene easily transforms to naphthalene by H-assisted isomerization. An analysis of the effect of pressure on the

Isolation of a naphthalene-degrading strain from activated sludge and bioaugmentation with it in a MBR treating coal gasification wastewater.

PubMed

Xu, Peng; Ma, Wencheng; Han, Hongjun; Jia, Shengyong; Hou, Baolin

2015-03-01

A highly effective naphthalene-degrading bacterial strain was isolated from acclimated activated sludge from a coal gasification wastewater plant, and identified as a Streptomyces sp., designated as strain QWE-35. The optimal pH and temperature for naphthalene degradation were 7.0 and 35°C. The presence of additional glucose and methanol significantly increased the degradation efficiency of naphthalene. The strain showed tolerance to the toxicity of naphthalene at a concentration as great as 200 mg/L. The Andrews mode could be fitted to the degradation kinetics data well over a wide range of initial naphthalene concentrations (10-200 mg/L), with kinetic values q max = 0.84 h(-1), K s = 40.39 mg/L, and K i = 193.76 mg/L. Metabolic intermediates were identified by gas chromatography and mass spectrometry, allowing a new degradation pathway for naphthalene to be proposed for the first time. Strain QWE-35 was added into a membrane bioreactor (MBR) to enhance the treatment of real coal gasification wastewater. The results showed that the removal of chemical oxygen demand and total nitrogen were similar between bioaugmented and non-bioaugmented MBRs, however, significant removal of naphthalene was obtained in the bioaugmented reactor. The findings suggest a potential bioremediation role of Streptomyces sp. QWE-35 in the removal of naphthalene from wastewaters.

Research Needs Related to Naphthalene Assessment (2005, Workshop)

EPA Science Inventory

EPA has announced the release of the final report from the 2005 peer consultation workshop which sought expert opinion on research needs related to the mode of action of the inhalation carcinogenicity of naphthalene. This report is a summary of the main points of presentations an...

Infrared spectroscopy of polycyclic aromatic hydrocarbon cations. 1: Matrix-isolated naphthalene and perdeuterated naphthalene

NASA Technical Reports Server (NTRS)

Hudgins, D. M.; Sandford, S. A.; Allamandola, Louis J.

1994-01-01

Ionized polycyclic aromatic hydrocarbons (PAHs) are thought to constitute an important component of the interstellar medium. Despite this fact, the infrared spectroscopic properties of ionized PAHs are almost unknown. The results we present here derive from our ongoing spectroscopic study of matrix isolated PAH ions and include the spectra of the naphthalene cation, C10H8(+), and its fully deuterated analog, C10D8(+), between 4000 and 200/cm. Ions are generated by in situ Lyman-alpha photoionization of the neutral precursor. Bands of the C10H8(+) ion are observed at 1525.7, 1518.8, 1400.9, 1218.0, 1216.9, 1214.9, 1023.2, and 758.7/cm. Positions and relative intensities of these bands agree well with those in the available literature. The 758.7/cm band has not previously been reported. C10D8(+) ion bands appear at 1466.2, 1463.8, 1379.4, 1373.8, 1077.3, 1075.4, and 1063.1/cm. Compared to the analogous modes in the neutral molecule, the intensities of the cation's CC modes are enhanced by an order of magnitude, while CH modes are depressed by this same factor. Integrated absorption intensities are calculated for the strongest bands of C10H8 and for the observed bands of C10H8(+). Absolute intensities derived for the naphthalene cation differ from earlier experimental results by a factor of approximately 50, and from theoretical predictions by a factor of approximately 300. Reasons for these discrepancies and from the astronomical implications of PAH cation spectra are discussed.

Rotation and diffusion of naphthalene on Pt(111)

NASA Astrophysics Data System (ADS)

Kolsbjerg, E. L.; Goubert, G.; McBreen, P. H.; Hammer, B.

2018-03-01

The behavior of naphthalene on Pt(111) surfaces is studied by combining insight from scanning tunneling microscopy (STM) and van der Waals enabled density functional theory. Adsorption, diffusion, and rotation are investigated by a series of variable temperature STM experiments revealing naphthalene ability to rotate on-site with ease with a rotational barrier of 0.69 eV. Diffusion to neighbouring sites is found to be more difficult. The experimental results are in good agreement with the theoretical investigations which confirm that the barrier for diffusion is slightly higher than the one for rotation. The theoretical barriers for rotation and translation are found to be 0.75 and 0.78 eV, respectively. An automatic mapping of the possible diffusion pathways reveals very detailed diffusion paths with many small local minima that would have been practically impossible to find manually. This automated procedure provides detailed insight into the preferred diffusion pathways that are important for our understanding of molecule-substrate interactions.

Decomposition of naphthalene by dc gliding arc gas discharge.

PubMed

Yu, Liang; Li, Xiaodong; Tu, Xin; Wang, Yu; Lu, Shengyong; Yan, Jianhua

2010-01-14

Gliding arc discharge has been proved to be effective in treatment of gas and liquid contaminants. In this study, physical characteristics of dc gliding arc discharge and its application to naphthalene destruction are investigated with different external resistances and carrier gases. The decomposition rate increases with increasing of oxygen concentration and decreases with external resistance. This value can be achieved up to 92.3% at the external resistance of 50 kOmega in the oxygen discharge, while the highest destruction energy efficiency reaches 3.6 g (kW h)(-1) with the external resistance of 93 kOmega. Possible reaction pathways and degradation mechanisms in the plasma with different gases are proposed by qualitative analysis of postdestructed products. In the air and oxygen gliding arc discharges, the naphthalene degradation is mainly governed by reactions with oxygen-derived radicals.

Allosteric Models for Cooperative Polymerization of Linear Polymers

PubMed Central

Miraldi, Emily R.; Thomas, Peter J.; Romberg, Laura

2008-01-01

In the cytoskeleton, unfavorable nucleation steps allow cells to regulate where, when, and how many polymers assemble. Nucleated polymerization is traditionally explained by a model in which multistranded polymers assemble cooperatively, whereas linear, single-stranded polymers do not. Recent data on the assembly of FtsZ, the bacterial homolog of tubulin, do not fit either category. FtsZ can polymerize into single-stranded protofilaments that are stable in the absence of lateral interactions, but that assemble cooperatively. We developed a model for cooperative polymerization that does not require polymers to be multistranded. Instead, a conformational change allows subunits in oligomers to associate with high affinity, whereas a lower-affinity conformation is favored in monomers. We derive equations for calculating polymer concentrations, subunit conformations, and the apparent affinity of subunits for polymer ends. Certain combinations of equilibrium constants produce the sharp critical concentrations characteristic of cooperative polymerization. In these cases, the low-affinity conformation predominates in monomers, whereas virtually all polymers are composed of high-affinity subunits. Our model predicts that the three routes to forming HH dimers all involve unstable intermediates, limiting nucleation. The mathematical framework developed here can represent allosteric assembly systems with a variety of biochemical interpretations, some of which can show cooperativity, and others of which cannot. PMID:18502809

The naphthalene state of the science symposium: objectives, organization, structure, and charge.

PubMed

Belzer, Richard B; Bus, James S; Cavalieri, Ercole L; Lewis, Steven C; North, D Warner; Pleus, Richard C

2008-07-01

This report provides a summary of the objectives, organization, structure and charge for the naphthalene state of the science symposium (NS(3)), Monterey, CA, October 9-12, 2006. A 1-day preliminary conference was held followed by a 3-day state of the science symposium covering four topics judged by the Planning Committee to be crucial for developing valid and reliable scientific estimates of low-dose human cancer risk from naphthalene. The Planning Committee reviewed the relevant scientific literature to identify singularly knowledgeable researchers and a pool of scientists qualified to serve as expert panelists. In two cases, independent scientists were commissioned to develop comprehensive reviews of the relevant science in a specific area for which no leading researcher could be identified. Researchers and expert panelists alike were screened for conflicts of interest. All policy issues related to risk assessment practices and risk management were scrupulously excluded. NS(3) was novel in several ways and provides an innovative model for the effective use of peer review to identify scientific uncertainties and propose research strategies for reducing or eliminating them prior to the conduct of risk assessment.

Self-Consistent Field Lattice Model for Polymer Networks.

PubMed

Tito, Nicholas B; Storm, Cornelis; Ellenbroek, Wouter G

2017-12-26

A lattice model based on polymer self-consistent field theory is developed to predict the equilibrium statistics of arbitrary polymer networks. For a given network topology, our approach uses moment propagators on a lattice to self-consistently construct the ensemble of polymer conformations and cross-link spatial probability distributions. Remarkably, the calculation can be performed "in the dark", without any prior knowledge on preferred chain conformations or cross-link positions. Numerical results from the model for a test network exhibit close agreement with molecular dynamics simulations, including when the network is strongly sheared. Our model captures nonaffine deformation, mean-field monomer interactions, cross-link fluctuations, and finite extensibility of chains, yielding predictions that differ markedly from classical rubber elasticity theory for polymer networks. By examining polymer networks with different degrees of interconnectivity, we gain insight into cross-link entropy, an important quantity in the macroscopic behavior of gels and self-healing materials as they are deformed.

Thermal modeling of the lithium/polymer battery

NASA Astrophysics Data System (ADS)

Pals, C. R.

1994-10-01

Research in the area of advanced batteries for electric-vehicle applications has increased steadily since the 1990 zero-emission-vehicle mandate of the California Air Resources Board. Due to their design flexibility and potentially high energy and power densities, lithium/polymer batteries are an emerging technology for electric-vehicle applications. Thermal modeling of lithium/polymer batteries is particularly important because the transport properties of the system depend exponentially on temperature. Two models have been presented for assessment of the thermal behavior of lithium/polymer batteries. The one-cell model predicts the cell potential, the concentration profiles, and the heat-generation rate during discharge. The cell-stack model predicts temperature profiles and heat transfer limitations of the battery. Due to the variation of ionic conductivity and salt diffusion coefficient with temperature, the performance of the lithium/polymer battery is greatly affected by temperature. Because of this variation, it is important to optimize the cell operating temperature and design a thermal management system for the battery. Since the thermal conductivity of the polymer electrolyte is very low, heat is not easily conducted in the direction perpendicular to cell layers. Temperature profiles in the cells are not as significant as expected because heat-generation rates in warmer areas of the cell stack are lower than heat-generation rates in cooler areas of the stack. This nonuniform heat-generation rate flattens the temperature profile. Temperature profiles as calculated by this model are not as steep as those calculated by previous models that assume a uniform heat-generation rate.

Kinetics of sorption of polyaromatic hydrocarbons onto granular activated carbon and Macronet hyper-cross-linked polymers (MN200).

PubMed

Valderrama, C; Cortina, J L; Farran, A; Gamisans, X; Lao, C

2007-06-01

Polymeric supports are presented as an alternative to granular activated carbon (GAC) for organic contaminant removal from groundwater using permeable reactive barriers (PRB). The search for suitable polymeric sorbents for hydrocarbon extraction from aqueous streams has prompted the synthesis of new resins incorporating new functionalities or modifying the polymer network properties that solve many of the existing problems. Between them, the new type of polymeric sorbents Macronet Hypersol containing a styrene-divinylbenzene macroporous hyperreticulated network has been evaluated. Because of their potential sorptive properties, tests were conducted to determine the feasibility of using them as a low-cost reactive material for groundwater applications. The present work describes the sorption of six polycyclic hydrocarbons (PAHs) from aqueous solution onto both Macronet polymeric sorbent MN200 and granular activated carbon. Batch experiments were performed to determine loading rates of a family of PAHs (naphthalene, fluorene, anthracene, acenaphthene, pyrene, and fluoranthene), from a simple two-rings PAH (naphthalene) up to a four-ring PAH (pyrene). The behavior of a non-functionalized Macronet support (MN200) was compared with the behavior of a recognized material, granular activated carbon (GAC). Analyses of the respective rate data with three theoretical models (pseudo-first- and pseudo-second-order reaction models and the Elovich model) were used to describe the PAH sorption kinetics. Sorption rate constants were determined by graphical analysis of the proposed models. The study showed that sorption systems followed a pseudo-first-order reaction model, although the pseudo-second-order reaction model provides an acceptable description of the sorption process. Graphical analysis showed that the sorption process with activated carbon is a more complex process than the one observed for hyper-cross-linked polymers (MN200). A simulation of the barrier thickness needed

Spectroscopic investigation of oxygen- and water-induced electron trapping and charge transport instabilities in n-type polymer semiconductors.

PubMed

Di Pietro, Riccardo; Fazzi, Daniele; Kehoe, Tom B; Sirringhaus, Henning

2012-09-12

We present an optical spectroscopy study on the role of oxygen and water in electron trapping and storage/bias-stress degradation of n-type polymer field-effect transistors based on one of the most widely studied electron transporting conjugated polymers, poly{[N,N9-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,59-(2,29-bisthiophene)} (P(NDI2OD-T2)). We combine results obtained from charge accumulation spectroscopy, which allow optical quantification of the concentration of mobile and trapped charges in the polymer film, with electrical characterization of P(NDI2OD-T2) organic field-effect transistors to study the mechanism for storage and bias-stress degradation upon exposure to dry air/oxygen and humid nitrogen/water environments, thus separating the effect of the two molecules and determining the nature of their interaction with the polymer. We find that the stability upon oxygen exposure is limited by an interaction between the neutral polymer and molecular oxygen leading to a reduction in electron mobility in the bulk of the semiconductor. We use density functional theory quantum chemical calculations to ascribe the drop in mobility to the formation of a shallow, localized, oxygen-induced trap level, 0.34 eV below the delocalized lowest unoccupied molecular orbital of P(NDI2OD-T2). In contrast, the stability of the polymer anion against water is limited by two competing reactions, one involving the electrochemical oxidation of the polymer anion by water without degradation of the polymer and the other involving a radical anion-catalyzed chemical reaction of the polymer with water, in which the electron can be recycled and lead to further degradation reactions, such that a significant portion of the film is degraded after prolonged bias stressing. Using Raman spectroscopy, we have been able to ascribe this to a chemical interaction of water with the naphthalene diimide unit of the polymer. The degradation mechanisms identified here

Naphthalene Planar Laser-Induced Fluorescence Imaging of Orion Multi-Purpose Crew Vehicle Heat Shield Ablation Products

NASA Astrophysics Data System (ADS)

Combs, Christopher S.; Clemens, Noel T.; Danehy, Paul M.

2013-11-01

The Orion Multi-Purpose Crew Vehicle (MPCV) calls for an ablative heat shield. In order to better design this heat shield and others that will undergo planetary entry, an improved understanding of the ablation process is required. Given that ablation is a multi-physics process involving heat and mass transfer, codes aiming to predict heat shield ablation are in need of experimental data pertaining to the turbulent transport of ablation products for validation. At The University of Texas at Austin, a technique is being developed that uses planar laser-induced fluorescence (PLIF) of a low-temperature sublimating ablator (naphthalene) to visualize the transport of ablation products in a supersonic flow. Since ablation at reentry temperatures can be difficult to recreate in a laboratory setting it is desirable to create a limited physics problem and simulate the ablation process at relatively low temperature conditions using naphthalene. A scaled Orion MPCV model with a solid naphthalene heat shield has been tested in a Mach 5 wind tunnel at various angles of attack in the current work. PLIF images have shown high concentrations of scalar in the capsule wake region, intermittent turbulent structures on the heat shield surface, and interesting details of the capsule shear layer structure. This work was supported by a NASA Office of the Chief Technologist's Space Technology Research Fellowship (NNX11AN55H).

Molecular modeling of polymers 16. Gaseous diffusion in polymers: a quantitative structure-property relationship (QSPR) analysis.

PubMed

Patel, H C; Tokarski, J S; Hopfinger, A J

1997-10-01

The purpose of this study was to identify the key physicochemical molecular properties of polymeric materials responsible for gaseous diffusion in the polymers. Quantitative structure-property relationships, QSPRs were constructed using a genetic algorithm on a training set of 16 polymers for which CO2, N2, O2 diffusion constants were measured. Nine physicochemical properties of each of the polymers were used in the trial basis set for QSPR model construction. The linear cross-correlation matrices were constructed and investigated for colinearity among the members of the training sets. Common water diffusion measures for a limited training set of six polymers was used to construct a "semi-QSPR" model. The bulk modulus of the polymer was overwhelmingly found to be the dominant physicochemical polymer property that governs CO2, N2 and O2 diffusion. Some secondary physicochemical properties controlling diffusion, including conformational entropy, were also identified as correlation descriptors. Very significant QSPR diffusion models were constructed for all three gases. Cohesive energy was identified as the main correlation physicochemical property with aqueous diffusion measures. The dominant role of polymer bulk modulus on gaseous diffusion makes it difficult to develop criteria for selective transport of gases through polymers. Moreover, high bulk moduli are predicted to be necessary for effective gas barrier materials. This property requirement may limit the processing and packaging features of the material. Aqueous diffusion in polymers may occur by a different mechanism than gaseous diffusion since bulk modulus does not correlate with aqueous diffusion, but rather cohesive energy of the polymer.

Bacterial Chemotaxis to Naphthalene and Nitroarene Compounds

DTIC Science & Technology

2008-07-31

Qualitative capillary assays showing chemotaxis of succinate-grown 17 (uninduced) and induced (succinate plus salicylate -grown) Acidovorax sp. JS42...succinate plus 2NT- or succinate plus salicylate -grown) wild-type Acidovorax sp. JS42 cells List of Tables Table 1. Summary of chemotaxis...mM salicylate , or naphthalene crystals. Noble agar (1.8%; Difco) was used to solidify MSB medium for plates. For plasmid selection and maintenance

Actuator model of electrostrictive polymers (EPs) for microactuators

NASA Astrophysics Data System (ADS)

Kim, Hunmo; Oh, Sinjong; Hwang, Kyoil; Choi, Hyoukryeol; Jeon, Jaewook; Nam, Jaedo

2001-07-01

Recently, Electrostrictive polymers (EPs) are studied for micro-actuator, because of similarity of body tissue. Electrostrictive polymers (EPs) are based on the deformation of dielectric elastomer polymer in the presence of an electric field. Modeling of electrostrictive polymer has been studied, which is about voltage and displacement. And there are many parameters such as Young's modulus, voltage, thickness of EPs, pre-strain, dielectric, frequency and temperature which effect to movement of EPs. To do exact modeling, all parameters are included. In order to use as actuator, we accurately understood about the parameter that we refer above. And we have to execute modeling which parameters are considered. We used FEM in order to understand effects of parameters. Specially, because of pre-strain effects are very important, we derive the relations of stress and strain by using elastic strain energy.

Simultaneous determination of caffeine and paracetamol by square wave voltammetry at poly(4-amino-3-hydroxynaphthalene sulfonic acid)-modified glassy carbon electrode.

PubMed

Tefera, Molla; Geto, Alemnew; Tessema, Merid; Admassie, Shimelis

2016-11-01

Poly(4-amino-3-hydroxynaphthalene sulfonic acid)-modified glassy carbon electrode (poly(AHNSA)/GCE) was prepared for simultaneous determination of caffeine and paracetamol using square-wave voltammetry. The method was used to study the effects of pH and scan rate on the voltammetric response of caffeine and paracetamol. Linear calibration curves in the range of 10-125μM were obtained for both caffeine and paracetamol in acetate buffer solution of pH 4.5 with a correlation coefficient of 0.9989 and 0.9986, respectively. The calculated detection limits (S/N=3) were 0.79μM for caffeine and 0.45μM for paracetamol. The effects of some interfering substances in the determination of caffeine and paracetamol were also studied and their interferences were found to be negligible which proved the selectivity of the modified electrode. The method was successfully applied for the quantitative determination of caffeine and paracetamol in Coca-Cola, Pepsi-Cola and tea samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

Noncovalent Interactions of DNA Bases with Naphthalene and Graphene.

PubMed

Cho, Yeonchoo; Min, Seung Kyu; Yun, Jeonghun; Kim, Woo Youn; Tkatchenko, Alexandre; Kim, Kwang S

2013-04-09

The complexes of a DNA base bound to graphitic systems are studied. Considering naphthalene as the simplest graphitic system, DNA base-naphthalene complexes are scrutinized at high levels of ab initio theory including coupled cluster theory with singles, doubles, and perturbative triples excitations [CCSD(T)] at the complete basis set (CBS) limit. The stacked configurations are the most stable, where the CCSD(T)/CBS binding energies of guanine, adenine, thymine, and cytosine are 9.31, 8.48, 8.53, 7.30 kcal/mol, respectively. The energy components are investigated using symmetry-adapted perturbation theory based on density functional theory including the dispersion energy. We compared the CCSD(T)/CBS results with several density functional methods applicable to periodic systems. Considering accuracy and availability, the optB86b nonlocal functional and the Tkatchenko-Scheffler functional are used to study the binding energies of nucleobases on graphene. The predicted values are 18-24 kcal/mol, though many-body effects on screening and energy need to be further considered.

Origin of organic matter in the early solar system. VII - The organic polymer in carbonaceous chondrites

NASA Technical Reports Server (NTRS)

Hayatsu, R.; Matsuoka, S.; Anders, E.; Scott, R. G.; Studier, M. H.

1977-01-01

Degradation techniques, including pyrolysis, depolymerization, and oxidation, were used to study the insoluble polymer from the Murchison C2 chondrite. Oxidation with Cr2O7(2-) or O2/UV led to the identification of 15 aromatic ring systems. Of 11 aliphatic acids identified, three dicarboxylic acids presumably came from hydroaromatic portions of the polymer, whereas eight monocarboxylic acids probably derive from bridging groups or ring substituents. Depolymerization with CF3COO4 yielded some of the same ring systems, as well as alkanes (C1 through C8) and alkenes (C2 through C8), alkyl (C1 through C5) benzenes and naphthalenes, and methyl- or dimethyl -indene, -indane, -phenol, -pyrrole, and -pyridine. All these compounds were detected below 200 C, and are therefore probably indigenous constituents. The properties of the meteoritic polymer were compared with the properties of a synthetic polymer produced by the Fischer-Tropsch reaction. It is suggested that the meteoritic polymer was also produced by surface catalysis.

A Semi-Empirical Formula of the Dependence of the Fluorescence Intensity of Naphthalene on Temperature and the Oxygen Concentration

NASA Astrophysics Data System (ADS)

An, B.; Wang, Z.-G.; Yang, L.-C.; Li, X.-P.

2017-09-01

Two-ring aromatics, such as naphthalene, are important fluorescent components of kerosene in the planar laser-induced fluorescent (PLIF) technique. Quantifying measurements of kerosene vapor concentrations by PLIF require a prior knowledge of the fluorescence intensity of naphthalene over a wide temperature and oxygen concentration range. To promote the application of PLIF, a semi-empirical formula based on the collision theory and experimental data at the laser wavelength of 266 nm and a pressure of 0.1 MPa is established to predict the fluorescence intensity of naphthalene at different temperatures and oxygen concentrations. This formula takes vibrational states, temperature, and oxygen quenching into account. Verified by published experimental data, the formula can predict the fluorescence intensity of naphthalene with an error less than 9%.

Nitration of naphthalene and remarks on the mechanism of electrophilic aromatic nitration.

PubMed

Olah, G A; Narang, S C; Olah, J A

1981-06-01

Naphthalene was nitrated with a variety of nitrating agents. Comparison of data with Perrin's electrochemical nitration [Perrin, C. L. (1977) J. Am. Chem. Soc. 99, 5516-5518] shows that nitration of naphthalene gives an alpha-nitronaphthalene to beta-nitronaphthalene ratio that varies between 9 and 29 and is thus not constant. Perrin's data, therefore, are considered to be inconclusive evidence for the proposed one-electron transfer mechanism for the nitration of naphthalene and other reactive aromatics. Moodie and Schoefield [Hoggett, J. G., Moodie, R. B., Penton, J. R. & Schoefield, K. (1971) Nitration and Aromatic Reactivity (Cambridge Univ. Press, London)], as well as Perrin, independently concluded that, in the general scheme of nitration of reactive aromatics, there is the necessity to introduce into the classical Ingold mechanism an additional step involving a distinct intermediate preceding the formation of the Wheland intermediate (sigma complexes). This view coincides with our two-step mechanistic picture [Kuhn, S. J. & Olah, G. A. (1961) J. Am. Chem. Soc. 83, 4564-4571] of the nitronium salt nitration of aromatic hydrocarbons (including benzene and toluene), in which low substrate selectivity but high positional selectivity was found, indicating the independence of substrate from positional selectivity.

Nitration of naphthalene and remarks on the mechanism of electrophilic aromatic nitration*

PubMed Central

Olah, George A.; Narang, Subhash C.; Olah, Judith A.

1981-01-01

Naphthalene was nitrated with a variety of nitrating agents. Comparison of data with Perrin's electrochemical nitration [Perrin, C. L. (1977) J. Am. Chem. Soc. 99, 5516-5518] shows that nitration of naphthalene gives an α-nitronaphthalene to β-nitronaphthalene ratio that varies between 9 and 29 and is thus not constant. Perrin's data, therefore, are considered to be inconclusive evidence for the proposed one-electron transfer mechanism for the nitration of naphthalene and other reactive aromatics. Moodie and Schoefield [Hoggett, J. G., Moodie, R. B., Penton, J. R. & Schoefield, K. (1971) Nitration and Aromatic Reactivity (Cambridge Univ. Press, London)], as well as Perrin, independently concluded that, in the general scheme of nitration of reactive aromatics, there is the necessity to introduce into the classical Ingold mechanism an additional step involving a distinct intermediate preceding the formation of the Wheland intermediate (σ complexes). This view coincides with our two-step mechanistic picture [Kuhn, S. J. & Olah, G. A. (1961) J. Am. Chem. Soc. 83, 4564-4571] of the nitronium salt nitration of aromatic hydrocarbons (including benzene and toluene), in which low substrate selectivity but high positional selectivity was found, indicating the independence of substrate from positional selectivity. PMID:16593026

Behavior of 2,6-bis(decyloxy)naphthalene inside lipid bilayer.

PubMed

Kepczynski, Mariusz; Kumorek, Marta; Stepniewski, Michał; Róg, Tomasz; Kozik, Bartłomiej; Jamróz, Dorota; Bednar, Jan; Nowakowska, Maria

2010-12-02

Interactions between small organic molecules and lipid or cell membranes are important because of their role in the distribution of biologically active substances inside the membrane and their permeation through the cell membranes. In the current paper, we have explored the effect of the attachment of long hydrocarbon tails on the behavior of small organic molecule inside the lipid membrane. Naphthalene with two decyloxy groups attached at the opposite sites of the ring (2,6-bis(decyloxy)naphthalene, 3) was synthesized and incorporated into phosphatidylcholine (PC) vesicles. Fluorescence methods as well as molecular dynamic (MD) simulations were used to estimate the position, orientation, and migration of compound 3 in PC bilayer. It was found that the naphthalene ring of compound 3 resides in the upper acyl chain region of the bilayer and the hydrocarbon tails are directed to the center of the bilayer. As was shown with cryotransmission electron microscopy (cryo-TEM), such lipidlike conformation enables compound 3 to be incorporated into liposomes at a very high content without their disintegration. Moreover, compound 3 can migrate from one leaflet to other. The mechanism of this process is, however, different from that characteristic of the flip-flop event of lipid molecules in the membrane. Finally, the possible application of compound 3 as a rotational molecular probe for monitoring fluidity of liposomal membrane in the acyl side chain region was checked by studies of the effect of cholesterol on the fluorescence anisotropy of 3.

A numerical model to simulate foams during devolatilization of polymers

NASA Astrophysics Data System (ADS)

Khan, Irfan; Dixit, Ravindra

2014-11-01

Customers often demand that the polymers sold in the market have low levels of volatile organic compounds (VOC). Some of the processes for making polymers involve the removal of volatiles to the levels of parts per million (devolatilization). During this step the volatiles are phase separated out of the polymer through a combination of heating and applying lower pressure, creating foam with the pure polymer in liquid phase and the volatiles in the gas phase. The efficiency of the devolatilization process depends on predicting the onset of solvent phase change in the polymer and volatiles mixture accurately based on the processing conditions. However due to the complex relationship between the polymer properties and the processing conditions this is not trivial. In this work, a bubble scale model is coupled with a bulk scale transport model to simulate the processing conditions of polymer devolatilization. The bubble scale model simulates the nucleation and bubble growth based on the classical nucleation theory and the popular ``influence volume approach.'' As such it provides the information of bubble size distribution and number density inside the polymer at any given time and position. This information is used to predict the bulk properties of the polymer and its behavior under the applied processing conditions. Initial results of this modeling approach will be presented.

Optical biosensor for environmental on-line monitoring of naphthalene and salicylate bioavailability with an immobilized bioluminescent catabolic reporter bacterium.

PubMed Central

Heitzer, A; Malachowsky, K; Thonnard, J E; Bienkowski, P R; White, D C; Sayler, G S

1994-01-01

An optical whole-cell biosensor based on a genetically engineered bioluminescent catabolic reporter bacterium was developed for continuous on-line monitoring of naphthalene and salicylate bioavailability and microbial catabolic activity potential in waste streams. The bioluminescent reporter bacterium, Pseudomonas fluorescens HK44, carries a transcriptional nahG-luxCDABE fusion for naphthalene and salicylate catabolism. Exposure to either compound resulted in inducible bioluminescence. The reporter culture was immobilized onto the surface of an optical light guide by using strontium alginate. This biosensor probe was then inserted into a measurement cell which simultaneously received the waste stream solution and a maintenance medium. Exposure under defined conditions to both naphthalene and salicylate resulted in a rapid increase in bioluminescence. The magnitude of the response and the response time were concentration dependent. Good reproducibility of the response was observed during repetitive perturbations with either naphthalene or salicylate. Exposure to other compounds, such as glucose and complex nutrient medium or toluene, resulted in either minor bioluminescence increases after significantly longer response times compared with naphthalene or no response, respectively. The environmental utility of the biosensor was tested by using real pollutant mixtures. A specific bioluminescence response was obtained after exposure to either an aqueous solution saturated with JP-4 jet fuel or an aqueous leachate from a manufactured-gas plant soil, since naphthalene was present in both pollutant mixtures. PMID:8017932

Reversible Shape Memory Polymers and Composites: Synthesis, Modeling and Design

DTIC Science & Technology

2013-03-01

Polymer; and (iii) Development of a Shape Memory Assisted Self - Healing Polymer. Page 3 of 19 Mather/FA9550-09-1-0195 IV(i) Modeling and Model...0195 IV(iii) Development of a Shape Memory Assisted Self - Healing Polymer Erika D. Rodriguez, X. Luo, and P.T. Mather, “Linear and Crosslinked...Poly (ε- Caprolactone) Polymers for Shape Memory Assisted Self - Healing (SMASH),” ACS Applied Materials and Interfaces 3 152-161 (2011). Self

A spatially nonlocal model for polymer-penetrant diffusion

NASA Astrophysics Data System (ADS)

Edwards, D. A.

Diffusion of a penetrant in a polymer entanglement network cannot be described by Fick's Law alone; rather, one must incorporate other nonlocal effects. In contrast to previous viscoelastic models which have modeled these effects through hereditary integrals in time, a new model is presented exploiting the disparate lengths of the polymer in the glassy (dry) and rubbery (saturated) states. This model leads to a partial integrodifferential equation which is nonlocal in space. The system is recast as a moving boundary-value problem between sets of coupled partial differential equations. Using singular perturbation techniques, sorption in a semi-infinite polymer is studied on several time scales with varying exposed interface conditions. Though some of the results match with those from viscoelastic models, new physically relevant behaviors also appear. These include the formation of stopping fronts and overshoot in the pseudostress.

Ion-Conducting Organic/Inorganic Polymers

NASA Technical Reports Server (NTRS)

Kinder, James D.; Meador, Mary Ann B.

2007-01-01

Ion-conducting polymers that are hybrids of organic and inorganic moieties and that are suitable for forming into solid-electrolyte membranes have been invented in an effort to improve upon the polymeric materials that have been used previously for such membranes. Examples of the prior materials include perfluorosulfonic acid-based formulations, polybenzimidazoles, sulfonated polyetherketone, sulfonated naphthalenic polyimides, and polyethylene oxide (PEO)-based formulations. Relative to the prior materials, the polymers of the present invention offer greater dimensional stability, greater ease of formation into mechanically resilient films, and acceptably high ionic conductivities over wider temperature ranges. Devices in which films made of these ion-conducting organic/inorganic polymers could be used include fuel cells, lithium batteries, chemical sensors, electrochemical capacitors, electrochromic windows and display devices, and analog memory devices. The synthesis of a polymer of this type (see Figure 1) starts with a reaction between an epoxide-functionalized alkoxysilane and a diamine. The product of this reaction is polymerized by hydrolysis and condensation of the alkoxysilane group, producing a molecular network that contains both organic and inorganic (silica) links. The silica in the network contributes to the ionic conductivity and to the desired thermal and mechanical properties. Examples of other diamines that have been used in the reaction sequence of Figure 1 are shown in Figure 2. One can use any of these diamines or any combination of them in proportions chosen to impart desired properties to the finished product. Alternatively or in addition, one could similarly vary the functionality of the alkoxysilane to obtain desired properties. The variety of available alkoxysilanes and diamines thus affords flexibility to optimize the organic/inorganic polymer for a given application.

An Overview of the Toxicity of Naphthalene, EDB and Ethanol

EPA Science Inventory

This presentation is a short summary of information on the toxicity and carcinogenicity of naphthalene and 1,2-dibromoethane (EDB) that is available in the EPA Integrated Risk Information System (IRIS) and information on the toxicity of ethanol available from the Health, Environm...

IRIS Toxicological Review of Naphthalene (Scoping and Problem Formulation Materials)

EPA Science Inventory

In July 2014, EPA released scoping and problem formulation materials for new IRIS assessments of ethylbenzene and naphthalene for public comment and discussion. The scoping information was based on input from EPA's program and regional offices and was provided for informational p...

Heterogeneous nucleation of polymorphs on polymer surfaces: polymer-molecule interactions using a heterogeneous dielectric solvation model.

PubMed

Wahlberg, Nanna; Madsen, Anders Ø; Mikkelsen, Kurt V

2018-06-09

We have investigated the mechanism of the nucleation of acetaminophen on poly(methyl-methacrylate) and poly(vinyl-acetate) utilizing a combination of quantum mechanical computations and electrostatic models. We have used a heterogeneous dielectric solvation model to determine the stability of different orientations of acetaminophen on polymer surfaces. We find that for the nucleation of acetaminophen on the polymer surfaces in vacuum, the most stable orientation is a flat orientation. For the nucleation process in solution where acetaminophen and the polymer surface are surrounded by a solvent, we find that the heterogeneous dielectric solvation model predicts that a sideways orientation is the most stable orientation.

Plastic flow modeling in glassy polymers

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

Clements, Brad

2010-12-13

recently developed glassy polymer model. While polymers are well known for their non-equilibrium deviatoric behavior we have found the need for incorporating both equilibrium and non-equilibrium volumetric behavior into our theory. Experimental evidence supporting the notion of non-equilibrium volumetric behavior will be summarized. Our polymer yield model accurately captures the stress plateau, softening and hardening and its yield stress predictions agree well with measured values for several glassy polymers including PMMA, PC, and an epoxy resin. We then apply our theory to plate impact experiments in an attempt to address the questions associated with high rate polymer yield in uniaxial strain configurations.« less

Penetration of naphthalene, n-hexadecane, and 2,4-dinitrotoluene into southern yellow pine under conditions modeling spills and floods

Treesearch

I.E. Popova; M.K. Beklemishev; C.R. Frihart; W.S. Seames; T.J. Sundstrom; E.I. Kozliak

2006-01-01

This paper investigates the penetration of three common contaminants into building grade southern yellow pine wood samples under the conditions experienced during chemical spills. Contaminants (n-hexadecane, naphthalene, and 2,4-dinitrotoluene) were applied in their 14C-labeled forms to 5-to 9-cm-long pieces of southern yellow pine at ambient conditions. The impact of...

A core-substituted naphthalene diimide fluoride sensor.

PubMed

Bhosale, Sheshanath V; Bhosale, Sidhanath V; Kalyankar, Mohan B; Langford, Steven J

2009-12-03

The synthesis and characterization of a highly fluorescent core-substituted naphthalene diimide sensor (varphi = 0.34) bearing a bis-sulfonamide group is described. The compound shows a unique selectivity and reactivity for the fluoride ion over other anions in CHCl(3) by a two-stage deprotonation process leading to a colorimetric response. In DMSO solution, the sensor is shown to be highly selective for fluoride (K(a) approximately 10(6) M(-1)) over other anions with more pronounced changes in absorption characteristics.

Mechanistic modelling of drug release from polymer-coated and swelling and dissolving polymer matrix systems.

PubMed

Kaunisto, Erik; Marucci, Mariagrazia; Borgquist, Per; Axelsson, Anders

2011-10-10

The time required for the design of a new delivery device can be sensibly reduced if the release mechanism is understood and an appropriate mathematical model is used to characterize the system. Once all the model parameters are obtained, in silico experiments can be performed, to provide estimates of the release from devices with different geometries and compositions. In this review coated and matrix systems are considered. For coated formulations, models describing the diffusional drug release, the osmotic pumping drug release, and the lag phase of pellets undergoing cracking in the coating due to the build-up of a hydrostatic pressure are reviewed. For matrix systems, models describing pure polymer dissolution, diffusion in the polymer and drug release from swelling and eroding polymer matrix formulations are reviewed. Importantly, the experiments used to characterize the processes occurring during the release and to validate the models are presented and discussed. Copyright © 2011 Elsevier B.V. All rights reserved.

Microwave-assisted intramolecular dehydrogenative Diels-Alder reactions for the synthesis of functionalized naphthalenes/solvatochromic dyes.

PubMed

Kocsis, Laura S; Benedetti, Erica; Brummond, Kay M

2013-04-01

Functionalized naphthalenes have applications in a variety of research fields ranging from the synthesis of natural or biologically active molecules to the preparation of new organic dyes. Although numerous strategies have been reported to access naphthalene scaffolds, many procedures still present limitations in terms of incorporating functionality, which in turn narrows the range of available substrates. The development of versatile methods for direct access to substituted naphthalenes is therefore highly desirable. The Diels-Alder (DA) cycloaddition reaction is a powerful and attractive method for the formation of saturated and unsaturated ring systems from readily available starting materials. A new microwave-assisted intramolecular dehydrogenative DA reaction of styrenyl derivatives described herein generates a variety of functionalized cyclopenta[b]naphthalenes that could not be prepared using existing synthetic methods. When compared to conventional heating, microwave irradiation accelerates reaction rates, enhances yields, and limits the formation of undesired byproducts. The utility of this protocol is further demonstrated by the conversion of a DA cycloadduct into a novel solvatochromic fluorescent dye via a Buchwald-Hartwig palladium-catalyzed cross-coupling reaction. Fluorescence spectroscopy, as an informative and sensitive analytical technique, plays a key role in research fields including environmental science, medicine, pharmacology, and cellular biology. Access to a variety of new organic fluorophores provided by the microwave-assisted dehydrogenative DA reaction allows for further advancement in these fields.

Microwave-assisted Intramolecular Dehydrogenative Diels-Alder Reactions for the Synthesis of Functionalized Naphthalenes/Solvatochromic Dyes

PubMed Central

Kocsis, Laura S.; Benedetti, Erica; Brummond, Kay M.

2013-01-01

Functionalized naphthalenes have applications in a variety of research fields ranging from the synthesis of natural or biologically active molecules to the preparation of new organic dyes. Although numerous strategies have been reported to access naphthalene scaffolds, many procedures still present limitations in terms of incorporating functionality, which in turn narrows the range of available substrates. The development of versatile methods for direct access to substituted naphthalenes is therefore highly desirable. The Diels-Alder (DA) cycloaddition reaction is a powerful and attractive method for the formation of saturated and unsaturated ring systems from readily available starting materials. A new microwave-assisted intramolecular dehydrogenative DA reaction of styrenyl derivatives described herein generates a variety of functionalized cyclopenta[b]naphthalenes that could not be prepared using existing synthetic methods. When compared to conventional heating, microwave irradiation accelerates reaction rates, enhances yields, and limits the formation of undesired byproducts. The utility of this protocol is further demonstrated by the conversion of a DA cycloadduct into a novel solvatochromic fluorescent dye via a Buchwald-Hartwig palladium-catalyzed cross-coupling reaction. Fluorescence spectroscopy, as an informative and sensitive analytical technique, plays a key role in research fields including environmental science, medicine, pharmacology, and cellular biology. Access to a variety of new organic fluorophores provided by the microwave-assisted dehydrogenative DA reaction allows for further advancement in these fields. PMID:23609566

Influence of surface oxides on the adsorption of naphthalene onto multiwalled carbon nanotubes.

PubMed

Cho, Hyun-Hee; Smith, Billy A; Wnuk, Joshua D; Fairbrother, D Howard; Ball, William P

2008-04-15

As greater quantities of carbon nanotubes (CNTs) enter the environment, they will have an increasingly important effect on the availability and transport of aqueous contaminants. As a consequence of purification, deliberate surface functionalization, and/or exposure to oxidizing agents after release to the environment, CNTs often contain surface oxides (i.e., oxygen containing functional groups). To probe the influence that surface oxides exert on CNT sorption properties, multiwalled CNTs (MWCNTs) with varying oxygen concentrations were studied with respect to their sorption properties toward naphthalene. For pristine (as-received) MWCNTs, the sorption capacity was intermediate between that of a natural char and a granular activated carbon. Sorption data also reveal that a linear relationship exists between the oxygen content of MWCNTs and their maximum adsorption capacity for naphthalene, with 10% surface oxygen concentration resulting in a roughly 70% decrease in maximum adsorption capacity. The relative distribution of sorption energies, as characterized by Freundlich isotherm exponents was, however, unaffected by oxidation. Thus, the data are consistent with the idea that incorporated surface oxides create polar regions that reduce the surface area available for naphthalene sorption. These results highlight the important role of surface chemistry in controlling the environmental properties of CNTs.

Gas-phase naphthalene concentration data recovery in ambient air and its relevance as a tracer of sources of volatile organic compounds

NASA Astrophysics Data System (ADS)

Uria-Tellaetxe, Iratxe; Navazo, Marino; de Blas, Maite; Durana, Nieves; Alonso, Lucio; Iza, Jon

2016-04-01

Despite the toxicity of naphthalene and the fact that it is a precursor of atmospheric photooxidants and secondary aerosol, studies on ambient gas-phase naphthalene are generally scarce. Moreover, as far as we are concerned, this is the first published one using long-term hourly ambient gas-phase naphthalene concentrations. In this work, it has been also demonstrated the usefulness of ambient gas-phase naphthalene to identify major sources of volatile organic compounds (VOC) in complex scenarios. Initially, in order to identify main benzene emission sources, hourly ambient measurements of 60 VOC were taken during a complete year together with meteorological data in an urban/industrial area. Later, due to the observed co-linearity of some of the emissions, a procedure was developed to recover naphthalene concentration data from recorded chromatograms to use it as a tracer of the combustion and distillation of petroleum products. The characteristic retention time of this compound was determined comparing previous GC-MS and GC-FID simultaneous analysis by means of relative retention times, and its concentration was calculated by using relative response factors. The obtained naphthalene concentrations correlated fairly well with ethene (r = 0.86) and benzene (r = 0.92). Besides, the analysis of daily time series showed that these compounds followed a similar pattern, very different from that of other VOC, with minimum concentrations at day-time. This, together with the results from the assessment of the meteorological dependence pointed out a coke oven as the major naphthalene and benzene emitting sources in the study area.

Human health risk constrained naphthalene-contaminated groundwater remediation management through an improved credibility method.

PubMed

Li, Jing; Lu, Hongwei; Fan, Xing; Chen, Yizhong

2017-07-01

In this study, a human health risk constrained groundwater remediation management program based on the improved credibility is developed for naphthalene contamination. The program integrates simulation, multivariate regression analysis, health risk assessment, uncertainty analysis, and nonlinear optimization into a general framework. The improved credibility-based optimization model for groundwater remediation management with consideration of human health risk (ICOM-HHR) is capable of not only effectively addressing parameter uncertainties and risk-exceeding possibility in human health risk but also providing a credibility level that indicates the satisfaction of the optimal groundwater remediation strategies with multiple contributions of possibility and necessity. The capabilities and effectiveness of ICOM-HHR are illustrated through a real-world case study in Anhui Province, China. Results indicate that the ICOM-HHR would generate double remediation cost yet reduce approximately 10 times of the naphthalene concentrations at monitoring wells, i.e., mostly less than 1 μg/L, which implies that the ICOM-HHR usually results in better environmental and health risk benefits. And it is acceptable to obtain a better environmental quality and a lower health risk level with sacrificing a certain economic benefit.

Validating clustering of molecular dynamics simulations using polymer models.

PubMed

Phillips, Joshua L; Colvin, Michael E; Newsam, Shawn

2011-11-14

Molecular dynamics (MD) simulation is a powerful technique for sampling the meta-stable and transitional conformations of proteins and other biomolecules. Computational data clustering has emerged as a useful, automated technique for extracting conformational states from MD simulation data. Despite extensive application, relatively little work has been done to determine if the clustering algorithms are actually extracting useful information. A primary goal of this paper therefore is to provide such an understanding through a detailed analysis of data clustering applied to a series of increasingly complex biopolymer models. We develop a novel series of models using basic polymer theory that have intuitive, clearly-defined dynamics and exhibit the essential properties that we are seeking to identify in MD simulations of real biomolecules. We then apply spectral clustering, an algorithm particularly well-suited for clustering polymer structures, to our models and MD simulations of several intrinsically disordered proteins. Clustering results for the polymer models provide clear evidence that the meta-stable and transitional conformations are detected by the algorithm. The results for the polymer models also help guide the analysis of the disordered protein simulations by comparing and contrasting the statistical properties of the extracted clusters. We have developed a framework for validating the performance and utility of clustering algorithms for studying molecular biopolymer simulations that utilizes several analytic and dynamic polymer models which exhibit well-behaved dynamics including: meta-stable states, transition states, helical structures, and stochastic dynamics. We show that spectral clustering is robust to anomalies introduced by structural alignment and that different structural classes of intrinsically disordered proteins can be reliably discriminated from the clustering results. To our knowledge, our framework is the first to utilize model polymers

Validating clustering of molecular dynamics simulations using polymer models

PubMed Central

2011-01-01

Background Molecular dynamics (MD) simulation is a powerful technique for sampling the meta-stable and transitional conformations of proteins and other biomolecules. Computational data clustering has emerged as a useful, automated technique for extracting conformational states from MD simulation data. Despite extensive application, relatively little work has been done to determine if the clustering algorithms are actually extracting useful information. A primary goal of this paper therefore is to provide such an understanding through a detailed analysis of data clustering applied to a series of increasingly complex biopolymer models. Results We develop a novel series of models using basic polymer theory that have intuitive, clearly-defined dynamics and exhibit the essential properties that we are seeking to identify in MD simulations of real biomolecules. We then apply spectral clustering, an algorithm particularly well-suited for clustering polymer structures, to our models and MD simulations of several intrinsically disordered proteins. Clustering results for the polymer models provide clear evidence that the meta-stable and transitional conformations are detected by the algorithm. The results for the polymer models also help guide the analysis of the disordered protein simulations by comparing and contrasting the statistical properties of the extracted clusters. Conclusions We have developed a framework for validating the performance and utility of clustering algorithms for studying molecular biopolymer simulations that utilizes several analytic and dynamic polymer models which exhibit well-behaved dynamics including: meta-stable states, transition states, helical structures, and stochastic dynamics. We show that spectral clustering is robust to anomalies introduced by structural alignment and that different structural classes of intrinsically disordered proteins can be reliably discriminated from the clustering results. To our knowledge, our framework is the

The effects of energetic proton bombardment on polymeric materials: Experimental studies and degradation models

NASA Technical Reports Server (NTRS)

Coulter, D. R.; Gupta, A.; Smith, M. V.; Fornes, R. E.

1986-01-01

This report describes 3 MeV proton bombardment experiments on several polymeric materials of interest to NASA carried out on the Tandem Van De Graff Accelerator at the California Institute of Technology's Kellogg Radiation Laboratory. Model aromatic and aliphatic polymers such as poly(1-vinyl naphthalene) and poly(methyl methacrylate), as well as polymers for near term space applications such as Kapton, Epoxy and Polysulfone, have been included in this study. Chemical and physical characterization of the damage products have been carried out in order to develop a model of the interaction of these polymers with the incident proton beam. The proton bombardment methodology developed at the Jet Propulsion Laboratory and reported here is part of an ongoing study on the effects of space radiation on polymeric materials. The report is intended to provide an overview of the mechanistic, as well as the technical and experimental, issues involved in such work rather than to serve as an exhaustive description of all the results.

CORRELATION OF POLYCHLORINATED NAPHTHALENES WITH POLYCHLORINATED DIBENZOFURANS FORMED FROM WASTE INCINERATION

EPA Science Inventory

Isomer composition of polychlorinated naphthalenes (PCNs) was measured for municipal waste incinerator fly ash samples,and for emission samples produced from soot and copper deposit experiments conducted at EPA. Two types of PCN isomer patterns were identified. One pattern cxonta...

Modelling Polymer Deformation during 3D Printing

NASA Astrophysics Data System (ADS)

McIlroy, Claire; Olmsted, Peter

Three-dimensional printing has the potential to transform manufacturing processes, yet improving the strength of printed parts, to equal that of traditionally-manufactured parts, remains an underlying issue. The fused deposition modelling technique involves melting a thermoplastic, followed by layer-by-layer extrusion to fabricate an object. The key to ensuring strength at the weld between layers is successful inter-diffusion. However, prior to welding, both the extrusion process and the cooling temperature profile can significantly deform the polymer micro-structure and, consequently, how well the polymers are able to ``re-entangle'' across the weld. In particular, polymer alignment in the flow can cause de-bonding of the layers and create defects. We have developed a simple model of the non-isothermal extrusion process to explore the effects that typical printing conditions and material rheology have on the conformation of a polymer melt. In particular, we incorporate both stretch and orientation using the Rolie-Poly constitutive equation to examine the melt structure as it flows through the nozzle, the subsequent alignment with the build plate and the resulting deformation due to the fixed nozzle height, which is typically less than the nozzle radius.

Modeling Lignin Polymerization. I. Simulation Model of Dehydrogenation Polymers1[OA

PubMed Central

van Parijs, Frederik R.D.; Morreel, Kris; Ralph, John; Boerjan, Wout; Merks, Roeland M.H.

2010-01-01

Lignin is a heteropolymer that is thought to form in the cell wall by combinatorial radical coupling of monolignols. Here, we present a simulation model of in vitro lignin polymerization, based on the combinatorial coupling theory, which allows us to predict the reaction conditions controlling the primary structure of lignin polymers. Our model predicts two controlling factors for the β-O-4 content of syringyl-guaiacyl lignins: the supply rate of monolignols and the relative amount of supplied sinapyl alcohol monomers. We have analyzed the in silico degradability of the resulting lignin polymers by cutting the resulting lignin polymers at β-O-4 bonds. These are cleaved in analytical methods used to study lignin composition, namely thioacidolysis and derivatization followed by reductive cleavage, under pulping conditions, and in some lignocellulosic biomass pretreatments. PMID:20472753

Adsorption induced enzyme denaturation: the role of polymer hydrophobicity in adsorption and denaturation of alpha-chymotrypsin on allyl glycidyl ether (AGE)-ethylene glycol dimethacrylate (EGDM) copolymers.

PubMed

Lahari, Challa; Jasti, Lakshmi S; Fadnavis, Nitin W; Sontakke, Kalpana; Ingavle, Ganesh; Deokar, Sarika; Ponrathnam, Surendra

2010-01-19

Effects of changes in hydrophobicity of polymeric support on structure and activity of alpha-chymotrypsin (E.C. 3.4.21.1) have been studied with copolymers of allyl glycidyl ether (AGE) and ethylene glycol dimethacrylate (EGDM) with increasing molar ratio of EGDM to AGE (cross-link density 0.05 to 1.5). The enzyme is readily adsorbed from aqueous buffer at room temperature following Langmuir adsorption isotherms in unexpectedly large amounts (25% w/w). Relative hydrophobicity of the copolymers has been assessed by studying adsorption of naphthalene and Fmoc-methionine by the series of copolymers from aqueous solutions. Polymer hydrophobicity appears to increase linearly on increasing cross-link density from 0.05 to 0.25. Further increase in cross-link density causes a decrease in naphthalene binding but has little effect on binding of Fmoc-Met. Binding of alpha-chymotrypsin to these copolymers follow the trend for Fmoc-methionine binding, rather than naphthalene binding, indicating involvement of polar interactions along with hydrophobic interactions during binding of protein to the polymer. The adsorbed enzyme undergoes extensive denaturation (ca. 80%) with loss of both tertiary and secondary structure on contact with the copolymers as revealed by fluorescence, CD and Raman spectra of the adsorbed protein. Comparison of enzyme adsorption behavior with Eupergit C, macroporous Amberlite XAD-2, and XAD-7 suggests that polar interactions of the EGDM ester functional groups with the protein play a significant role in enzyme denaturation.

IRIS Toxicological Review of Naphthalene (2014, Scoping and Problem Formulation Materials)

EPA Science Inventory

In July 2014, EPA released scoping and problem formulation materials for new IRIS assessments of ethylbenzene and naphthalene for public comment and discussion. The scoping information was based on input from EPA's program and regional offices and was provided for informational p...

NAPHTHALENE TOXICITY IN CD-1 MICE: GENERAL TOXICOLOGY AND IMMUNOTOXICOLOGY

EPA Science Inventory

The purpose of this study was to evaluate the acute and subchronic toxicity, and effects on immune function, of naphthalene (NAP) in random-bred CD-1 mice. The acute oral LD50 of this compound was 533 and 710 mg/kg in male and female mice, respectively. Fourteen- and ninety-day d...

Photophysical properties of Schiff's bases from 3-(1,3-benzothiazol-2-yl)-2-hydroxy naphthalene-1-carbaldehyde.

PubMed

Satam, Manjaree A; Telore, Rahul D; Sekar, Nagaiyan

2014-11-11

A series of novel Schiff's bases have been synthesized from 3-(1,3-benzothiazol-2-yl)-2-hydroxynaphthalene-1-carbaldehyde. The presence of hydroxyl group ortho to the benzothiazolyl group as well as the imine linkage lead to the occurrence of excited state intramolecular proton transfer process. The computational strategy was used to study the ESIPT process of the synthesized Schiff's bases, which revealed surprisingly that the keto form predominantly exists in the ground state contradicting the ESIPT process. Density functional theory and time dependent density functional theory have been used to investigate the structural parameters and photophysical properties in different solvents of one of the Schiff's bases. The experimental results correlate well with the computed results. All Schiff's bases show good thermal stability. Copyright © 2014 Elsevier B.V. All rights reserved.

Modeling Carbon-Black/Polymer Composite Sensors

PubMed Central

Lei, Hua; Pitt, William G.; McGrath, Lucas K.; Ho, Clifford K.

2012-01-01

Conductive polymer composite sensors have shown great potential in identifying gaseous analytes. To more thoroughly understand the physical and chemical mechanisms of this type of sensor, a mathematical model was developed by combining two sub-models: a conductivity model and a thermodynamic model, which gives a relationship between the vapor concentration of analyte(s) and the change of the sensor signals. In this work, 64 chemiresistors representing eight different carbon concentrations (8–60 vol% carbon) were constructed by depositing thin films of a carbon-black/polyisobutylene composite onto concentric spiral platinum electrodes on a silicon chip. The responses of the sensors were measured in dry air and at various vapor pressures of toluene and trichloroethylene. Three parameters in the conductivity model were determined by fitting the experimental data. It was shown that by applying this model, the sensor responses can be adequately predicted for given vapor pressures; furthermore the analyte vapor concentrations can be estimated based on the sensor responses. This model will guide the improvement of the design and fabrication of conductive polymer composite sensors for detecting and identifying mixtures of organic vapors. PMID:22518071

Numerical simulation of a lattice polymer model at its integrable point

NASA Astrophysics Data System (ADS)

Bedini, A.; Owczarek, A. L.; Prellberg, T.

2013-07-01

We revisit an integrable lattice model of polymer collapse using numerical simulations. This model was first studied by Blöte and Nienhuis (1989 J. Phys. A: Math. Gen. 22 1415) and it describes polymers with some attraction, providing thus a model for the polymer collapse transition. At a particular set of Boltzmann weights the model is integrable and the exponents ν = 12/23 ≈ 0.522 and γ = 53/46 ≈ 1.152 have been computed via identification of the scaling dimensions xt = 1/12 and xh = -5/48. We directly investigate the polymer scaling exponents via Monte Carlo simulations using the pruned-enriched Rosenbluth method algorithm. By simulating this polymer model for walks up to length 4096 we find ν = 0.576(6) and γ = 1.045(5), which are clearly different from the predicted values. Our estimate for the exponent ν is compatible with the known θ-point value of 4/7 and in agreement with very recent numerical evaluation by Foster and Pinettes (2012 J. Phys. A: Math. Theor. 45 505003).

An ellipsoid-chain model for conjugated polymer solutions

NASA Astrophysics Data System (ADS)

Lee, Cheng K.; Hua, Chi C.; Chen, Show A.

2012-02-01

We propose an ellipsoid-chain model which may be routinely parameterized to capture large-scale properties of semiflexible, amphiphilic conjugated polymers in various solvent media. The model naturally utilizes the defect locations as pivotal centers connecting adjacent ellipsoids (each currently representing ten monomer units), and a variant umbrella-sampling scheme is employed to construct the potentials of mean force (PMF) for specific solvent media using atomistic dynamics data and simplex optimization. The performances, both efficacy and efficiency, of the model are thoroughly evaluated by comparing the simulation results on long, single-chain (i.e., 300-mer) structures with those from two existing, finer-grained models for a standard conjugated polymer (i.e., poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene) or MEH-PPV) in two distinct solvents (i.e., chloroform or toluene) as well as a hybrid, binary-solvent medium (i.e., chloroform/toluene = 1:1 in number density). The coarse-grained Monte Carlo (CGMC) simulation of the ellipsoid-chain model is shown to be the most efficient—about 300 times faster than the coarse-grained molecular dynamics (CGMD) simulation of the finest CG model that employs explicit solvents—in capturing elementary single-chain structures for both single-solvent media, and is a few times faster than the coarse-grained Langevin dynamics (CGLD) simulation of another implicit-solvent polymer model with a slightly greater coarse-graining level than in the CGMD simulation. For the binary-solvent system considered, however, both of the two implicit-solvent schemes (i.e., CGMC and CGLD) fail to capture the effects of conspicuous concentration fluctuations near the polymer-solvent interface, arising from a pronounced coupling between the solvent molecules and different parts of the polymer. Essential physical implications are elaborated on the success as well as the failure of the two implicit-solvent CG schemes under varying solvent

Modeling electrical response of polymer-coated SAW resonators by equivalent circuit representation.

PubMed

Kshetrimayum, Roshan; Yadava, R D S; Tandon, R P

2011-07-01

The paper presents an equivalent circuit model of the polymer coated surface acoustic wave (SAW) resonators by combining coupling-of-mode (COM) description of SAW resonators and perturbation calculation of SAW propagation under polymer loading. An expression for the motional load produced by polymer coating is deduced in terms of COM parameters and polymer characteristics. In addition, expressions for the shifts in resonance frequency and attenuation due to polymer loading are obtained. Simulation results are presented for one-port and two-port resonator devices coated with viscoelastic thin polymer film. The influence of polymer film on resonator response is studied with regard to variations in film thickness and shear modulus. The model simplifies understanding of polymer-coated SAW sensors. Copyright © 2010 Elsevier B.V. All rights reserved.

Constitutive Modeling of Nanotube/Polymer Composites with Various Nanotube Orientations

NASA Technical Reports Server (NTRS)

Odegard, Gregory M.; Gates, Thomas S.

2002-01-01

In this study, a technique has been proposed for developing constitutive models for polymer composite systems reinforced with single-walled carbon nanotubes (SWNT) with various orientations with respect to the bulk material coordinates. A nanotube, the local polymer adjacent to the nanotube, and the nanotube/polymer interface have been modeled as an equivalent-continuum fiber by using an equivalent-continuum modeling method. The equivalent-continuum fiber accounts for the local molecular structure and bonding information and serves as a means for incorporating micromechanical analyses for the prediction of bulk mechanical properties of SWNT/polymer composite. As an example, the proposed approach is used for the constitutive modeling of a SWNT/LaRC-SI (with a PmPV interface) composite system, with aligned nanotubes, three-dimensionally randomly oriented nanotubes, and nanotubes oriented with varying degrees of axisymmetry. It is shown that the Young s modulus is highly dependent on the SWNT orientation distribution.

Molecular scale modeling of polymer imprint nanolithography.

PubMed

Chandross, Michael; Grest, Gary S

2012-01-10

We present the results of large-scale molecular dynamics simulations of two different nanolithographic processes, step-flash imprint lithography (SFIL), and hot embossing. We insert rigid stamps into an entangled bead-spring polymer melt above the glass transition temperature. After equilibration, the polymer is then hardened in one of two ways, depending on the specific process to be modeled. For SFIL, we cross-link the polymer chains by introducing bonds between neighboring beads. To model hot embossing, we instead cool the melt to below the glass transition temperature. We then study the ability of these methods to retain features by removing the stamps, both with a zero-stress removal process in which stamp atoms are instantaneously deleted from the system as well as a more physical process in which the stamp is pulled from the hardened polymer at fixed velocity. We find that it is necessary to coat the stamp with an antifriction coating to achieve clean removal of the stamp. We further find that a high density of cross-links is necessary for good feature retention in the SFIL process. The hot embossing process results in good feature retention at all length scales studied as long as coated, low surface energy stamps are used.

Mechanistic modelling of drug release from a polymer matrix using magnetic resonance microimaging.

PubMed

Kaunisto, Erik; Tajarobi, Farhad; Abrahmsen-Alami, Susanna; Larsson, Anette; Nilsson, Bernt; Axelsson, Anders

2013-03-12

In this paper a new model describing drug release from a polymer matrix tablet is presented. The utilization of the model is described as a two step process where, initially, polymer parameters are obtained from a previously published pure polymer dissolution model. The results are then combined with drug parameters obtained from literature data in the new model to predict solvent and drug concentration profiles and polymer and drug release profiles. The modelling approach was applied to the case of a HPMC matrix highly loaded with mannitol (model drug). The results showed that the drug release rate can be successfully predicted, using the suggested modelling approach. However, the model was not able to accurately predict the polymer release profile, possibly due to the sparse amount of usable pure polymer dissolution data. In addition to the case study, a sensitivity analysis of model parameters relevant to drug release was performed. The analysis revealed important information that can be useful in the drug formulation process. Copyright © 2013 Elsevier B.V. All rights reserved.

Stable-Isotope Probing of Bacteria Capable of Degrading Salicylate, Naphthalene, or Phenanthrene in a Bioreactor Treating Contaminated Soil

PubMed Central

Singleton, David R.; Powell, Sabrina N.; Sangaiah, Ramiah; Gold, Avram; Ball, Louise M.; Aitken, Michael D.

2005-01-01

[13C6]salicylate, [U-13C]naphthalene, and [U-13C]phenanthrene were synthesized and separately added to slurry from a bench-scale, aerobic bioreactor used to treat soil contaminated with polycyclic aromatic hydrocarbons. Incubations were performed for either 2 days (salicylate, naphthalene) or 7 days (naphthalene, phenanthrene). Total DNA was extracted from the incubations, the “heavy” and “light” DNA were separated, and the bacterial populations associated with the heavy fractions were examined by denaturing gradient gel electrophoresis (DGGE) and 16S rRNA gene clone libraries. Unlabeled DNA from Escherichia coli K-12 was added to each sample as an internal indicator of separation efficiency. While E. coli was not detected in most analyses of heavy DNA, a low number of E. coli sequences was recovered in the clone libraries associated with the heavy DNA fraction of [13C]phenanthrene incubations. The number of E. coli clones recovered proved useful in determining the relative amount of light DNA contamination of the heavy fraction in that sample. Salicylate- and naphthalene-degrading communities displayed similar DGGE profiles and their clone libraries were composed primarily of sequences belonging to the Pseudomonas and Ralstonia genera. In contrast, heavy DNA from the phenanthrene incubations displayed a markedly different DGGE profile and was composed primarily of sequences related to the Acidovorax genus. There was little difference in the DGGE profiles and types of sequences recovered from 2- and 7-day incubations with naphthalene, so secondary utilization of the 13C during the incubation did not appear to be an issue in this experiment. PMID:15746319

Synthesis of 3-alkyl naphthalenes as novel estrogen receptor ligands

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

Fang, Jing; Akwabi-Ameyaw, Adwoa; Britton, Jonathan E.

2009-06-24

A series of estrogen receptor ligands based on a 3-alkyl naphthalene scaffold was synthesized using an intramolecular enolate-alkyne cycloaromatization as the key step. Several of these compounds bearing a C6-OH group were shown to be high affinity ligands. All compounds had similar ER{alpha} and ER{beta} binding affinity ranging from micromolar to low nanomolar.

Rubber Bands as Model Polymers in Couette Flow

ERIC Educational Resources Information Center

Dunstan, Dave E.

2008-01-01

We present a simple device for demonstrating the essential aspects of polymers in flow in the classroom. Rubber bands are used as a macroscopic model of polymers to allow direct visual observation of the flow-induced changes in orientation and conformation. A transparent Perspex Couette cell, constructed from two sections of a tube, is used to…

Temperature gradient interaction chromatography of polymers: A molecular statistical model.

PubMed

Radke, Wolfgang; Lee, Sekyung; Chang, Taihyun

2010-11-01

A new model describing the retention in temperature gradient interaction chromatography of polymers is developed. The model predicts that polymers might elute in temperature gradient interaction chromatography in either an increasing or decreasing order or even nearly independent of molar mass, depending on the rate of the temperature increase relative to the flow rate. This is in contrast to solvent gradient elution, where polymers elute either in order of increasing molar mass or molar mass independent. The predictions of the newly developed model were verified with the literature data as well as new experimental data. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis, crystal growth, structural, thermal and optical properties of naphthalene picrate an organic NLO material.

PubMed

Chandramohan, A; Bharathikannan, R; Kandavelu, V; Chandrasekaran, J; Kandhaswamy, M A

2008-12-01

Crystalline substance of naphthalene picrate (NP) was synthesized and single crystals were grown using slow evaporation solution growth technique. The solubility of the naphthalene picrate complex was estimated using different solvents such as chloroform and benzene. The material was characterized by elemental analysis, powder X-ray diffraction (XRD), nuclear magnetic resonance (NMR) and fourier transform-infrared (FT-IR) techniques. The electronic absorption was studied through UV-vis spectrophotometer. Thermal behavior and stability of the crystal were studied using thermogravimetric (TG) and differential thermal analysis (DTA) techniques. The second harmonic generation (SHG) of the material was confirmed using Nd:YAG laser.

Summary Review of Health Effects Associated with Naphthalene: Health Issue Assessment (1987)

EPA Science Inventory

Naphthalene is released into ambient air via industrial gaseous and particulate emissions, tobacco use, and through consumer use. The data base concerning exposure of humans via inhalation and associated health effects is virtually nonexistent. Overexposure often results in acute...

Humidity effects on surface dielectric barrier discharge for gaseous naphthalene decomposition

NASA Astrophysics Data System (ADS)

Abdelaziz, Ayman A.; Ishijima, Tatsuo; Seto, Takafumi

2018-04-01

Experiments are performed using dry and humid air to clarify the effects of water vapour on the characteristics of surface dielectric barrier discharge (SDBD) and investigate its impact on the performance of the SDBD for decomposition of gaseous naphthalene in air stream. The current characteristics, including the discharge and the capacitive currents, are deeply analyzed and the discharge mechanism is explored. The results confirmed that the humidity affected the microdischarge distribution without affecting the discharge mode. Interestingly, it is found that the water vapour had a significant influence on the capacitance of the reactor due to its deposition on the discharge electrode and the dielectric, which, in turn, affects the power loss in the dielectric and the total power consumed in the reactor. Thus, the factor of the humidity effect on the power loss in the dielectric should be considered in addition to its effect on the attachment coefficient. Additionally, there was an optimum level of the humidity for the decomposition of naphthalene in the SDBD, and its value depended on the gas composition, where the maximum naphthalene decomposition efficiency in O2/H2O is achieved at the humidity level ˜10%, which was lower than that obtained in air/H2O (˜28%). The results also revealed that the role of the humidity in the decomposition efficiency was not significant in the humidified O2 at high power level. This was attributed to the significant increase in oxygen-derived species (such as O atoms and O3) at high power, which was enough to overcome the negative effects of the humidity.

Doping effect of nano-Ho{sub 2}O{sub 3} and naphthalene in MgB{sub 2} superconductor prepared by powder-in-sealed-tube method

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

Hansdah, J. S.; Sarun, P. M., E-mail: sarun.res@gmail.com

2015-03-21

The effect on crystal structure, critical temperature (T{sub C}), and critical current density (J{sub C}) of bulk MgB{sub 2} doped with nano-Ho{sub 2}O{sub 3} and naphthalene was studied. Among all the samples studied, the sample doped with 2.5 wt. % nano-Ho{sub 2}O{sub 3} have shown the best field dependent critical current density [J{sub C}(H)], i.e., 0.77 × 10{sup 5 }A/cm{sup 2} at 2 T and 10 K. While naphthalene doped MgB{sub 2} sample has shown the least J{sub C}(H) characteristics. The improved J{sub C}(H) characteristics in the nano-Ho{sub 2}O{sub 3} doped MgB{sub 2} samples are attributed to improved flux pinning properties due to the formation ofmore » HoB{sub 4} and in naphthalene doped MgB{sub 2} samples. The slight lower T{sub C} value (37.01 K) in naphthalene doped samples is attributed to the occurrence of lattice defect by the substitution of carbon at boron site of MgB{sub 2} superconductor. Lower ΔT{sub C} value implies the lesser anisotropy in all the synthesized samples. The flux pinning force density (F{sub P}/F{sub Pmax}) curves are theoretically analyzed using Dew-Hughes model. The result revealed that point pinning is the dominant pinning mechanism for nano-Ho{sub 2}O{sub 3} doped MgB{sub 2} samples, while, surface and grain boundary pinning become dominant with increasing naphthalene addition in nano-Ho{sub 2}O{sub 3} doped MgB{sub 2} samples.« less

Stability and molecular properties of the boron-nitrogen alternating analogs of azulene and naphthalene: a computational study.

PubMed

Catão, Anderson José Lopes; López-Castillo, Alejandro

2017-04-01

In this work, the spectroscopic information, stability and aromaticity of the boron-nitrogen azulene and naphthalene molecules are provided by the use of CC2 (geometry optimization, dipole moment, UV-vis spectrum calculations) and DFT (vibrational spectrum and NMR calculations) methodologies. One isomer of the investigated boron-nitrogen naphthalene (boroazanaphthalene) and two isomers of boron-nitrogen azulene, 1,3,4,6,8-pentaaza-2,3a,5,7,8a-pentaboraazulene (BN-azulene) and 2,3a,5,7,8a-pentaaza-1,3,4,6,8- pentaboraazulene (NB-azulene), are stable systems. However, these molecules have different properties, i.e., different stability, dipole moment, and aromaticity based on the NICS approach. BN-naphthalene has a high dipole moment magnitude showing high polar character, while naphthalene is apolar. BN- and NB-azulene are weakly polar, while ordinary azulene is highly polar in character. Also, substitution of C atoms by B and N atoms decreases the aromaticity. In the case of NB-azulene, the seven-membered ring has anti-aromaticity behavior while both rings of BN-azulene exhibit aromaticity. We expect that the new theoretical data provided in this work will be useful in identifying and characterizing experimentally the compounds investigated, and in helping our understanding of the chemistry of boron-nitrogen molecules. Graphical abstract Boron-nitrogen alternating analogs of azulene. Spectral distinction between isomers.

Spectral Dissimilarities Between AZULENE(C10H_8) and NAPHTHALENE(C10H_8)

NASA Astrophysics Data System (ADS)

Baba, Masaaki

2010-06-01

Polycyclic aromatic hydrocarbons (PAHs) are of great interest in the molecular structure and excited-state dynamics, and there have been extensive spectroscopic and theoretical studies. Azulene and naphthalene are bicyclic aromatic hydrocarbons composed of odd- and even-membered rings, respectively. First, they were discriminated by a theory of mutual polarizability. Naphthalene is an alternant hydrocarbon, but azulene is not. In contrast, spectral resemblances were found by John Platt et al., and were explained by their simple model of molecular orbital. However, the absorption and emission feature of the S_1 and S_2 states is completely different each other. We have investigated each rotational and vibrational structures, and radiative and nonradiative processes by means of high-resolution spectroscopy and ab initio calculation. The equilibrium structures in the S_0, S_1, and S_2 states are similar. This small structural change upon electronic excitation is common to PAH molecules composed of six-membered rings. The fluorescence quantum yield is high because radiationless transitions such as intersystem crossing (ISC) to the triplet state and internal conversion (IC) to the S_0 state are very slow in the S_1 state. In contrast, the S_1 state of azulene is nonfluorescent and the S_1 ← S_0 excitation energy is abnormally small. We consider that the potential energy curve of a b_2 vibration is shallower in the S_1 state, and therefore the vibronic coupling with the S_0 state is strong to enhance the IC process remarkably. This situation is, of course, due to its peculiar characteristics of odd-membered rings and molecular symmetry, which are completely different from the naphthalene molecule. C. A. Coulson and H. C. Longuet-Higgins, Proc. Roy. Soc. A, 191, 39 (1947) D. E. Mann, J. R. Platt, and H. B. Klevens, J. Chem. Phys., 17, 481 (1949) Y. Semba, M. Baba, et al., J. Chem. Phys., 131, 024303 (2009) K. Yoshida, M. Baba, et al., J. Chem. Phys., 130, 194304 (2009)

Relaxation model of radiation-induced conductivity in polymers

NASA Astrophysics Data System (ADS)

Zhutayeva, Yu. R.; Khatipov, S. A.

1999-05-01

The paper suggests a relaxation model of radiation-induced conductivity (RIC) in polymers. According to the model, the transfer of charges generated in the polymer volume by ionizing radiation takes place with the participation of molecular relaxation processes. The mechanism of electron transport consists in the transfer of the charge directly between traps when they draw close to one another due to the rotation of macromolecule segments. The numerical solutions of the corresponding kinetic equations for different distribution functions Q( τ) of the times of molecular relaxation and for different functions of the probability P( τ, τ') of charge transfer in the `overlapping' regions of the diffusion spheres of the segments are analyzed. The relaxation model provides an explanation of the non-Arrhenius behavior of the RIC temperature dependence, the power dependence of RIC on the dose rate with a power index in the interval 0.5-1.0, the appearance of maxima in the curves of the RIC temporal dependence and their irreversible character in the region of large dose rates (more than 1 Gy/s). The model can be used for interpreting polymer RIC in conditions of kinetic mobility of macromolecules.

Equivalent parameter model of 1-3 piezocomposite with a sandwich polymer

NASA Astrophysics Data System (ADS)

Zhang, Yanjun; Wang, Likun; Qin, Lei

2018-06-01

A theoretical model was developed to investigate the performance of 1-3 piezoelectric composites with a sandwich polymer. Effective parameters, such as the electromechanical coupling factor, longitudinal velocity, and characteristic acoustic impedance of the piezocomposite, were predicted using the developed model. The influences of volume fractions and components of the polymer phase on the effective parameters of the piezoelectric composite were studied. The theoretical model was verified experimentally. The proposed model can reproduce the effective parameters of 1-3 piezoelectric composites with a sandwich polymer in the thickness mode. The measured electromechanical coupling factor was improved by more than 9.8% over the PZT/resin 1-3 piezoelectric composite.

Photoinduced DNA Interstrand Cross-Link Formation by Naphthalene Boronates via a Carbocation.

PubMed

Wang, Yibin; Lin, Zechao; Fan, Heli; Peng, Xiaohua

2016-07-18

Most photoinduced DNA cross-link formation by a bifunctional aryl derivative is through a bisquinone methide. DNA cross-linking via a bisarylcarbocation remains a less explored area. We designed and synthesized a series of naphthalene boronates that produce DNA interstrand cross-links via a carbocation upon UV irradiation. A free radical was generated from the naphthalene boronates with 350 nm irradiation and further converted to a carbocation by electron transfer. The activation mechanism was determined using the orthogonal traps, 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) and methoxyamine that react with either the free radical or the carbocation but not both. This represents a novel example of photoinduced DNA cross-link formation via carbocations generated from a bisaryl derivative. This work provides information useful for the design of novel photoactivated DNA cross-linking agents. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

N,N′-Dicyclo­hexyl­naphthalene-1,8;4:5-dicarboximide

PubMed Central

Shukla, Deepak; Rajeswaran, Manju

2008-01-01

The title compound, C26H26N2O4, synthesized by the reaction of naphthalene-1,4,5,8-tetra­carboxylic acid anhydride and cyclo­hexyl­amine, exhibits good n-type semiconducting properties. Accordingly, thin-film transistor devices comprising this compound show n-type behavior with high field-effect electron moblity ca 6 cm2/Vs [Shukla, Nelson, Freeman, Rajeswaran, Ahearn, Meyer & Carey(2008 ▶). Chem. Mater. Submitted]. The asymmetric unit comprises one-quarter of the centrosymmetric mol­ecule in which all but two methyl­ene C atoms of the cyclo­hexane ring lie on a mirror plane; the point-group symmetry is 2/m. The naphthalene­diimide unit is strictly planar, and the cyclo­hexane rings adopt chair conformations with the diimide unit in an equatorial position on each ring. PMID:21201718

Semiflexible polymer dynamics with a bead-spring model

NASA Astrophysics Data System (ADS)

Barkema, Gerard T.; Panja, Debabrata; van Leeuwen, J. M. J.

2014-11-01

We study the dynamical properties of semiflexible polymers with a recently introduced bead-spring model. We focus on double-stranded DNA (dsDNA). The two parameters of the model, T* and ν, are chosen to match its experimental force-extension curve. In comparison to its groundstate value, the bead-spring Hamiltonian is approximated in the first order by the Hessian that is quadratic in the bead positions. The eigenmodes of the Hessian provide the longitudinal (stretching) and transverse (bending) eigenmodes of the polymer, and the corresponding eigenvalues match well with the established phenomenology of semiflexible polymers. At the Hessian approximation of the Hamiltonian, the polymer dynamics is linear. Using the longitudinal and transverse eigenmodes, for the linearized problem, we obtain analytical expressions of (i) the autocorrelation function of the end-to-end vector, (ii) the autocorrelation function of a bond (i.e. a spring, or a tangent) vector at the middle of the chain, and (iii) the mean-square displacement of a tagged bead in the middle of the chain, as the sum over the contributions from the modes—the so-called ‘mode sums’. We also perform simulations with the full dynamics of the model. The simulations yield numerical values of the correlations functions (i-iii) that agree very well with the analytical expressions for the linearized dynamics. This does not however mean that the nonlinearities are not present. In fact, we also study the mean-square displacement of the longitudinal component of the end-to-end vector that showcases strong nonlinear effects in the polymer dynamics, and we identify at least an effective t7/8 power-law regime in its time-dependence. Nevertheless, in comparison to the full mean-square displacement of the end-to-end vector the nonlinear effects remain small at all times—it is in this sense we state that our results demonstrate that the linearized dynamics suffices for dsDNA fragments that are shorter than or

Developing a Suitable Model for Water Uptake for Biodegradable Polymers Using Small Training Sets.

PubMed

Valenzuela, Loreto M; Knight, Doyle D; Kohn, Joachim

2016-01-01

Prediction of the dynamic properties of water uptake across polymer libraries can accelerate polymer selection for a specific application. We first built semiempirical models using Artificial Neural Networks and all water uptake data, as individual input. These models give very good correlations (R (2) > 0.78 for test set) but very low accuracy on cross-validation sets (less than 19% of experimental points within experimental error). Instead, using consolidated parameters like equilibrium water uptake a good model is obtained (R (2) = 0.78 for test set), with accurate predictions for 50% of tested polymers. The semiempirical model was applied to the 56-polymer library of L-tyrosine-derived polyarylates, identifying groups of polymers that are likely to satisfy design criteria for water uptake. This research demonstrates that a surrogate modeling effort can reduce the number of polymers that must be synthesized and characterized to identify an appropriate polymer that meets certain performance criteria.

Modified naphthalene diimide as a suitable tetraplex DNA ligand: application to cancer diagnosis and anti-cancer drug

NASA Astrophysics Data System (ADS)

Takenaka, Shigeori

2017-07-01

It is known that naphthalene diimide carrying two substituents binds to DNA duplex with threading intercalation. Naphthalene diimide carrying ferrocene moieties, ferrocenylnaphthalene diimide (FND), formed a stable complex with DNA duplex and an electrochemical gene detection was achieved with current signal generated from FND bound to the DNA duplex between target DNA and DNA probe immobilized electrode. FND couldn't bind to the mismatched and its surrounding region of DNA duplex and thus FND was applied to the precision detection of single nucleotide polymorphisms (SNPs) using the improved discrimination ability between fully matched and mismatched DNA hybrids and multi-electrode chip. Some of FND derivatives bound to telomere DNA tetraplex stronger than to DNA duplex and was applied to cancer diagnosis as a measure of the elongated telomere DNA with telomerase as a suitable maker of cancer. Furthermore, cyclic naphthalene diimides realized the extremely high preference for DNA tetraplex over DNA duplex. Such molecules will open an effective anti-cancer drug based on telomerase specific inhibitor.

Cadmium and naphthalene-induced hyperglycemia in the fiddler crab, Uca pugilator: Differential modes of action on the neutroendocrine system

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

Reddy, P.S.; Katyayani, R.V.; Fingerman, M.

1996-03-01

Hyperglycemia is a typical response of aquatic organisms to heavy metals. In crustaceans, the medulla terminalis X-organ-sinus gland neuroendocrine complex in the eyestalk is the source of the crustacean hyperglycemic hormone (CHH). The role of CHH in pollutant-induced b1ood glucose changes has only recently begun to be studied. Reddy provided evidence that CHH mediates cadmium-induced hyperglycemia in the red swamp crayfish, Procambarus clarkii. In a study of another hormonally-regulated function, color changes, cadmium exposure resulted in pigment in the melanophores of the fiddler crab, Uca pugilator, becoming less dispersed than in unexposed crabs. Earlier studies showed that, like cadmium, bothmore » a PCB, Aroclor 1242, and naphthalene induced black pigment aggregation in Uca poor. In general, when crabs are exposed to a pollutant, hydrocarbon or cadmium, they aggregate the pigment in their melanophores, but apparently by different mechanisms. Hydrocarbons appear to inhibit release of black pigment-dispersing hormone (BDPH), whereas cadmium appears to inhibit its synthesis. These apparent different modes of action of cadmium and naphthalene on the color change mechanism led us to compare the impact of these pollutants on the hormonal regulation of blood glucose in Uca pugilator. The present study was performed to determine (1) whether cadmium and naphthalene induce hyperglycemia in Uca pugilator, (2) whether CH has a role, if naphthalene and cadmium do induce hyperglycemia, and (3) the effects, if any, of cadmium and naphthalene on CHH activity in the eyestalk neuroendocrine complex.« less

Modeling semiflexible polymer networks

NASA Astrophysics Data System (ADS)

Broedersz, C. P.; MacKintosh, F. C.

2014-07-01

This is an overview of theoretical approaches to semiflexible polymers and their networks. Such semiflexible polymers have large bending rigidities that can compete with the entropic tendency of a chain to crumple up into a random coil. Many studies on semiflexible polymers and their assemblies have been motivated by their importance in biology. Indeed, cross-linked networks of semiflexible polymers form a major structural component of tissue and living cells. Reconstituted networks of such biopolymers have emerged as a new class of biological soft matter systems with remarkable material properties, which have spurred many of the theoretical developments discussed here. Starting from the mechanics and dynamics of individual semiflexible polymers, the physics of semiflexible bundles, entangled solutions, and disordered cross-linked networks are reviewed. Finally, recent developments on marginally stable fibrous networks, which exhibit critical behavior similar to other marginal systems such as jammed soft matter, are discussed.

AMEM-ADL Polymer Migration Estimation Model User's Guide

EPA Pesticide Factsheets

The user's guide of the Arthur D. Little Polymer Migration Estimation Model (AMEM) provides the information on how the model estimates the fraction of a chemical additive that diffuses through polymeric matrices.

Statistical models and NMR analysis of polymer microstructure

USDA-ARS?s Scientific Manuscript database

Statistical models can be used in conjunction with NMR spectroscopy to study polymer microstructure and polymerization mechanisms. Thus, Bernoullian, Markovian, and enantiomorphic-site models are well known. Many additional models have been formulated over the years for additional situations. Typica...

Attenuation of the Atmospheric Migration Ability of Polychlorinated Naphthalenes (PCN-2) Based on Three-dimensional QSAR Models with Full Factor Experimental Design.

PubMed

Gu, Wenwen; Chen, Ying; Li, Yu

2017-08-01

Based on the experimental subcooled liquid vapor pressures (P L ) of 17 polychlorinated naphthalene (PCN) congeners, one type of three-dimensional quantitative structure-activity relationship (3D-QSAR) models, comparative molecular similarity indices analysis (CoMSIA), was constructed with Sybyl software. Full factor experimental design was used to obtain the final regulation scheme for PCN, and then carry out modification of PCN-2 to significantly lower its P L . The contour maps of CoMSIA model showed that the migration ability of PCN decreases when the Cl atoms at the 2-, 3-, 4-, 5-, 6-, 7- and 8-positions of PCNs are replaced by electropositive groups. After modification of PCN-2, 12 types of new modified PCN-2 compounds were obtained with lnP L values two orders of magnitude lower than that of PCN-2. In addition, there are significant differences between the calculated total energies and energy gaps of the new modified compounds and those of PCN-2.

Ice growth from supercooled aqueous solutions of benzene, naphthalene, and phenanthrene.

PubMed

Liyana-Arachchi, Thilanga P; Valsaraj, Kalliat T; Hung, Francisco R

2012-08-23

Classical molecular dynamics (MD) were performed to investigate the growth of ice from supercooled aqueous solutions of benzene, naphthalene, or phenanthrene. The main objective of this study is to explore the fate of those aromatic molecules after freezing of the supercooled aqueous solutions, i.e., if these molecules become trapped inside the ice lattice or if they are displaced to the QLL or to the interface with air. Ice growth from supercooled aqueous solutions of benzene, naphthalene, or phenanthrene result in the formation of quasi-liquid layers (QLLs) at the air/ice interface that are thicker than those observed when pure supercooled water freezes. Naphthalene and phenanthrene molecules in the supercooled aqueous solutions are displaced to the air/ice interface during the freezing process at both 270 and 260 K; no incorporation of these aromatics into the ice lattice is observed throughout the freezing process. Similar trends were observed during freezing of supercooled aqueous solutions of benzene at 270 K. In contrast, a fraction of the benzene molecules become trapped inside the ice lattice during the freezing process at 260 K, with the rest of the benzene molecules being displaced to the air/ice interface. These results suggest that the size of the aromatic molecule in the supercooled aqueous solution is an important parameter in determining whether these molecules become trapped inside the ice crystals. Finally, we also report potential of mean force (PMF) calculations aimed at studying the adsorption of gas-phase benzene and phenanthrene on atmospheric air/ice interfaces. Our PMF calculations indicate the presence of deep free energy minima for both benzene and phenanthrene at the air/ice interface, with these molecules adopting a flat orientation at the air/ice interface.

LS-DYNA Implementation of Polymer Matrix Composite Model Under High Strain Rate Impact

NASA Technical Reports Server (NTRS)

Zheng, Xia-Hua; Goldberg, Robert K.; Binienda, Wieslaw K.; Roberts, Gary D.

2003-01-01

A recently developed constitutive model is implemented into LS-DYNA as a user defined material model (UMAT) to characterize the nonlinear strain rate dependent behavior of polymers. By utilizing this model within a micromechanics technique based on a laminate analogy, an algorithm to analyze the strain rate dependent, nonlinear deformation of a fiber reinforced polymer matrix composite is then developed as a UMAT to simulate the response of these composites under high strain rate impact. The models are designed for shell elements in order to ensure computational efficiency. Experimental and numerical stress-strain curves are compared for two representative polymers and a representative polymer matrix composite, with the analytical model predicting the experimental response reasonably well.

Pulsed radiolysis of model aromatic polymers and epoxy based matrix materials

NASA Technical Reports Server (NTRS)

Gupta, A.; Moacanin, J.; Liang, R.; Coulter, D.

1982-01-01

Models of primary processes leading to deactivation of energy deposited by a pulse of high energy electrons were derived for epoxy matrix materials and polyl-vinyl naphthalene. The basic conclusion is that recombination of initially formed charged states is complete within 1 nanosecond, and subsequent degradation chemistry is controlled by the reactivity of these excited states. Excited states in both systems form complexes with ground state molecules. These excimers or exciplexes have their characteristics emissive and absorptive properties and may decay to form separated pairs of ground state molecules, cross over to the triplet manifold or emit fluorescence. ESR studies and chemical analyses subsequent to pulse radiolysis were performed in order to estimate bond cleavage probabilities and net reaction rates. The energy deactivation models which were proposed to interpret these data have led to the development of radiation stabilization criteria for these systems.

Thermogravimetric study of thermal decontamination of soils polluted by hexachlorobenzene, 4-chlorobiphenyl, naphthalene, or n-decane.

PubMed

Risoul, V; Pichon, C; Trouvé, G; Peters, W A; Gilot, P; Prado, G

1999-02-15

To determine decontamination behavior as affected by temperature, shallow beds of a clay-rich, a calcerous, and a sedimentary soil, artificially polluted with hexachlorobenzene, 4-chlorobiphenyl, naphthalene, or n-decane, were separately heated at 5 degrees C min-1 in a thermogravimetric analyzer. Temperatures for deep cleaning of the calcerous and the sedimentary soil increased with increasing boiling point (bp) of the aromatic contaminants, but removal efficiencies still approached 100% well below the bp. Decontamination rates were therefore modelled according to a pollutant evaporation-diffusion transport model. For the calcerous and sedimentary soils, this model reasonably correlated removal of roughly the first 2/3 of the naphthalene, but gave only fair predictions for hexachlorobenzene and 4-chlorobiphenyl. It was necessary to heat the clay soil above the aromatics bp to achieve high decontamination efficiencies. Weight loss data imply that for temperatures from near ambient to as much as 150 degrees C, interactions of each aromatic with the clay soil, or its decomposition products, result in lower net volatilization of the contaminated vs. neat clay. A similar effect was observed in heating calcerous soil polluted with hexachlorobenzene from near ambient to about 140 degrees C. Decontamination mechanisms remain to be established, although the higher temperatures needed to remove aromatics from the clay may reflect a more prominent role for surface desorption than evaporation. This would be consistent with our estimates that the clay can accommodate all of the initial pollutant loadings within a single surface monolayer, whereas the calcerous and sedimentary soils cannot.

Identification and preliminary evaluation of polychlorinated naphthalene emissions from hot dip galvanizing plants.

PubMed

Liu, Guorui; Lv, Pu; Jiang, Xiaoxu; Nie, Zhiqiang; Liu, Wenbin; Zheng, Minghui

2015-01-01

Hot dip galvanizing (HDG) processes are sources of polychlorinated-p-dioxins and dibenzofurans (PCDD/Fs). Close correlations have been found between the concentration of PCDD/Fs and polychlorinated naphthalenes (PCNs) that are produced and released during industrial thermal processes. We speculated, therefore, that HDG plants are potential PCN sources. In this preliminary study, PCNs were analyzed in solid residues, ash and precipitate from three HDG plants of different sizes. The total PCN concentrations (∑2-8PCNs) in the residue samples ranged from 60.3 to 226pgg(-1). The PCN emission factors for the combined ash and precipitate residues from the HDG plants ranged from 75 to 178ngt(-1) for the dichlorinated and octachlorinated naphthalenes. The preliminary results suggested that the HDG industry might not currently be a significant source of PCN emissions. The trichloronaphthalenes were the dominant homologs followed by the dichloronaphthalenes and the tetrachloronaphthalenes. The PCN congeners CN37/33/34, CN52/60, CN66/67, and CN73 dominated the tetrachlorinated, pentachlorinated, hexachlorinated, and heptachlorinated naphthalene homologs, respectively. The PCNs emitted from the HDG plants had similar homolog distributions and congener profiles to the PCNs emitted from combustion plants and other metallurgical processes. The identification and preliminary evaluation of PCN emissions from HDG plants presented here will help in the prioritization of measures for controlling PCN emissions from industrial sources. Copyright © 2014 Elsevier Ltd. All rights reserved.

Enhanced oxidation of naphthalene using plasma activation of TiO2/diatomite catalyst.

PubMed

Wu, Zuliang; Zhu, Zhoubin; Hao, Xiaodong; Zhou, Weili; Han, Jingyi; Tang, Xiujuan; Yao, Shuiliang; Zhang, Xuming

2018-04-05

Non-thermal plasma technology has great potential in reducing polycyclic aromatic hydrocarbons (PAHs) emission. But in plasma-alone process, various undesired by-products are produced, which causes secondary pollutions. Here, a dielectric barrier discharge (DBD) reactor has been developed for the oxidation of naphthalene over a TiO 2 /diatomite catalyst at low temperature. In comparison to plasma-alone process, the combination of plasma and TiO 2 /diatomite catalyst significantly enhanced naphthalene conversion (up to 40%) and CO x selectivity (up to 92%), and substantially reduced the formation of aerosol (up to 90%) and secondary volatile organic compounds (up to near 100%). The mechanistic study suggested that the presence of the TiO 2 /diatomite catalyst intensified the electron energy in the DBD. Meantime, the energized electrons generated in the discharge activated TiO 2 , while the presence of ozone enhanced the activity of the TiO 2 /diatomite catalyst. This plasma-catalyst interaction led to the synergetic effect resulting from the combination of plasma and TiO 2 /diatomite catalyst, consequently enhanced the oxidation of naphthalene. Importantly, we have demonstrated the effectiveness of plasma to activate the photocatalyst for the deep oxidation of PAH without external heating, which is potentially valuable in the development of cost-effective gas cleaning process for the removal of PAHs in vehicle applications during cold start conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

A New Self-Consistent Field Model of Polymer/Nanoparticle Mixture

NASA Astrophysics Data System (ADS)

Chen, Kang; Li, Hui-Shu; Zhang, Bo-Kai; Li, Jian; Tian, Wen-De

2016-02-01

Field-theoretical method is efficient in predicting assembling structures of polymeric systems. However, it’s challenging to generalize this method to study the polymer/nanoparticle mixture due to its multi-scale nature. Here, we develop a new field-based model which unifies the nanoparticle description with the polymer field within the self-consistent field theory. Instead of being “ensemble-averaged” continuous distribution, the particle density in the final morphology can represent individual particles located at preferred positions. The discreteness of particle density allows our model to properly address the polymer-particle interface and the excluded-volume interaction. We use this model to study the simplest system of nanoparticles immersed in the dense homopolymer solution. The flexibility of tuning the interfacial details allows our model to capture the rich phenomena such as bridging aggregation and depletion attraction. Insights are obtained on the enthalpic and/or entropic origin of the structural variation due to the competition between depletion and interfacial interaction. This approach is readily extendable to the study of more complex polymer-based nanocomposites or biology-related systems, such as dendrimer/drug encapsulation and membrane/particle assembly.

40 CFR 61.134 - Standard: Naphthalene processing, final coolers, and final-cooler cooling towers.

Code of Federal Regulations, 2012 CFR

2012-07-01

... POLLUTANTS National Emission Standard for Benzene Emissions from Coke By-Product Recovery Plants § 61.134... are allowed from naphthalene processing, final coolers and final-cooler cooling towers at coke by...

40 CFR 61.134 - Standard: Naphthalene processing, final coolers, and final-cooler cooling towers.

Code of Federal Regulations, 2014 CFR

2014-07-01

... POLLUTANTS National Emission Standard for Benzene Emissions from Coke By-Product Recovery Plants § 61.134... are allowed from naphthalene processing, final coolers and final-cooler cooling towers at coke by...

40 CFR 61.134 - Standard: Naphthalene processing, final coolers, and final-cooler cooling towers.

Code of Federal Regulations, 2013 CFR

2013-07-01

... POLLUTANTS National Emission Standard for Benzene Emissions from Coke By-Product Recovery Plants § 61.134... are allowed from naphthalene processing, final coolers and final-cooler cooling towers at coke by...

40 CFR 61.134 - Standard: Naphthalene processing, final coolers, and final-cooler cooling towers.

Code of Federal Regulations, 2011 CFR

2011-07-01

... POLLUTANTS National Emission Standard for Benzene Emissions from Coke By-Product Recovery Plants § 61.134... are allowed from naphthalene processing, final coolers and final-cooler cooling towers at coke by...

Discovery of Antibiotics-derived Polymers for Gene Delivery using Combinatorial Synthesis and Cheminformatics Modeling

PubMed Central

Potta, Thrimoorthy; Zhen, Zhuo; Grandhi, Taraka Sai Pavan; Christensen, Matthew D.; Ramos, James; Breneman, Curt M.; Rege, Kaushal

2014-01-01

We describe the combinatorial synthesis and cheminformatics modeling of aminoglycoside antibiotics-derived polymers for transgene delivery and expression. Fifty-six polymers were synthesized by polymerizing aminoglycosides with diglycidyl ether cross-linkers. Parallel screening resulted in identification of several lead polymers that resulted in high transgene expression levels in cells. The role of polymer physicochemical properties in determining efficacy of transgene expression was investigated using Quantitative Structure-Activity Relationship (QSAR) cheminformatics models based on Support Vector Regression (SVR) and ‘building block’ polymer structures. The QSAR model exhibited high predictive ability, and investigation of descriptors in the model, using molecular visualization and correlation plots, indicated that physicochemical attributes related to both, aminoglycosides and diglycidyl ethers facilitated transgene expression. This work synergistically combines combinatorial synthesis and parallel screening with cheminformatics-based QSAR models for discovery and physicochemical elucidation of effective antibiotics-derived polymers for transgene delivery in medicine and biotechnology. PMID:24331709

A highly coarse-grained model to simulate entangled polymer melts.

PubMed

Zhu, You-Liang; Liu, Hong; Lu, Zhong-Yuan

2012-04-14

We introduce a highly coarse-grained model to simulate the entangled polymer melts. In this model, a polymer chain is taken as a single coarse-grained particle, and the creation and annihilation of entanglements are regarded as stochastic events in proper time intervals according to certain rules and possibilities. We build the relationship between the probability of appearance of an entanglement between any pair of neighboring chains at a given time interval and the rate of variation of entanglements which describes the concurrence of birth and death of entanglements. The probability of disappearance of entanglements is tuned to keep the total entanglement number around the target value. This useful model can reflect many characteristics of entanglements and macroscopic properties of polymer melts. As an illustration, we apply this model to simulate the polyethylene melt of C(1000)H(2002) at 450 K and further validate this model by comparing to experimental data and other simulation results.

Mathematical modeling of polymer flooding using the unstructured Voronoi grid

NASA Astrophysics Data System (ADS)

Kireev, T. F.; Bulgakova, G. T.; Khatmullin, I. F.

2017-12-01

Effective recovery of unconventional oil reserves necessitates development of enhanced oil recovery techniques such as polymer flooding. The study investigated the model of polymer flooding with effects of adsorption and water salinity. The model takes into account six components that include elements of the classic black oil model. These components are polymer, salt, water, dead oil, dry gas and dissolved gas. Solution of the problem is obtained by finite volume method on unstructured Voronoi grid using fully implicit scheme and the Newton’s method. To compare several different grid configurations numerical simulation of polymer flooding is performed. The oil rates obtained by a hexagonal locally refined Voronoi grid are shown to be more accurate than the oil rates obtained by a rectangular grid with the same number of cells. The latter effect is caused by high solution accuracy near the wells due to the local grid refinement. Minimization of the grid orientation effect caused by the hexagonal pattern is also demonstrated. However, in the inter-well regions with large Voronoi cells flood front tends to flatten and the water breakthrough moment is smoothed.

Molecular model for the diffusion of associating telechelic polymer networks

NASA Astrophysics Data System (ADS)

Ramirez, Jorge; Dursch, Thomas; Olsen, Bradley

Understanding the mechanisms of motion and stress relaxation of associating polymers at the molecular level is critical for advanced technological applications such as enhanced oil-recovery, self-healing materials or drug delivery. In associating polymers, the strength and rates of association/dissociation of the reversible physical crosslinks govern the dynamics of the network and therefore all the macroscopic properties, like self-diffusion and rheology. Recently, by means of forced Rayleigh scattering experiments, we have proved that associating polymers of different architectures show super-diffusive behavior when the free motion of single molecular species is slowed down by association/dissociation kinetics. Here we discuss a new molecular picture for unentangled associating telechelic polymers that considers concentration, molecular weight, number of arms of the molecules and equilibrium and rate constants of association/dissociation. The model predicts super-diffusive behavior under the right combination of values of the parameters. We discuss some of the predictions of the model using scaling arguments, show detailed results from Brownian dynamics simulations of the FRS experiments, and attempt to compare the predictions of the model to experimental data.

Modeling of nanosecond pulsed laser processing of polymers in air and water

NASA Astrophysics Data System (ADS)

Marla, Deepak; Zhang, Yang; Hattel, Jesper H.; Spangenberg, Jon

2018-07-01

Laser ablation of polymers in water is known to generate distinct surface characteristics as compared to that in air. In order to understand the role of ambient media during laser ablation of polymers, this paper aims to develop a physics-based model of the process considering the effect of ambient media. Therefore, in the present work, models are developed for laser ablation of polymers in air and water considering all the relevant physical phenomena such as laser–polymer interaction, plasma generation, plasma expansion and plasma shielding. The current work focuses on near-infrared laser radiation (λ = 1064 nm) of nanosecond pulse duration. The laser–polymer interaction at such wavelengths is purely photo-thermal in nature and the laser–plasma interaction is assumed to occur mainly by inverse-bremsstrahlung photon absorption. The computational model is based on the finite volume method using the Crank‑Nicholson scheme. The model predicts that underwater laser ablation results in subsurface heating effect in the polymer and confinement of the laser generated plasma, which makes it different from laser ablation in air. Plasma expansion velocities are much lower in water than in air. This results in an enhanced plasma shielding effect in the case of water. The predicted results of ablation depth versus fluence from the model are in qualitative agreement with those observed in experiments.

Horizontal Transfer of phnAc Dioxygenase Genes within One of Two Phenotypically and Genotypically Distinctive Naphthalene-Degrading Guilds from Adjacent Soil Environments

PubMed Central

Wilson, Mark S.; Herrick, James B.; Jeon, Che Ok; Hinman, David E.; Madsen, Eugene L.

2003-01-01

Several distinct naphthalene dioxygenases have been characterized to date, which provides the opportunity to investigate the ecological significance, relative distribution, and transmission modes of the different analogs. In this study, we showed that a group of naphthalene-degrading isolates from a polycyclic aromatic hydrocarbon (PAH)-contaminated hillside soil were phenotypically and genotypically distinct from naphthalene-degrading organisms isolated from adjacent, more highly contaminated seep sediments. Mineralization of 14C-labeled naphthalene by soil slurries suggested that the in situ seep community was more acclimated to PAHs than was the in situ hillside community. phnAc-like genes were present in diverse naphthalene-degrading isolates cultured from the hillside soil, while nahAc-like genes were found only among isolates cultured from the seep sediments. The presence of a highly conserved nahAc allele among gram-negative isolates from the coal tar-contaminated seep area provided evidence for in situ horizontal gene transfer and was reported previously (J. B. Herrick, K. G. Stuart-Keil, W. C. Ghiorse, and E. L. Madsen, Appl. Environ. Microbiol. 63:2330-2337, 1997). Natural horizontal transfer of the phnAc sequence was also suggested by a comparison of the phnAc and 16S ribosomal DNA sequences of the hillside isolates. Analysis of metabolites produced by cell suspensions and patterns of amplicons produced by PCR analysis suggested both genetic and metabolic diversity among the naphthalene-degrading isolates of the contaminated hillside. These results provide new insights into the distribution, diversity, and transfer of phnAc alleles and increase our understanding of the acclimation of microbial communities to pollutants. PMID:12676698

A Critical Review of Naphthalene Sources and Exposures Relevant to Indoor and Outdoor Air

PubMed Central

Jia, Chunrong; Batterman, Stuart

2010-01-01

Both the recent classification of naphthalene as a possible human carcinogen and its ubiquitous presence motivate this critical review of naphthalene’s sources and exposures. We evaluate the environmental literature on naphthalene published since 1990, drawing on nearly 150 studies that report emissions and concentrations in indoor, outdoor and personal air. While naphthalene is both a volatile organic compound and a polycyclic aromatic hydrocarbon, concentrations and exposures are poorly characterized relative to many other pollutants. Most airborne emissions result from combustion, and key sources include industry, open burning, tailpipe emissions, and cigarettes. The second largest source is off-gassing, specifically from naphthalene’s use as a deodorizer, repellent and fumigant. In the U.S., naphthalene’s use as a moth repellant has been reduced in favor of para-dichlorobenzene, but extensive use continues in mothballs, which appears responsible for some of the highest indoor exposures, along with off-label uses. Among the studies judged to be representative, average concentrations ranged from 0.18 to 1.7 μg m−3 in non-smoker’s homes, and from 0.02 to 0.31 μg m−3 outdoors in urban areas. Personal exposures have been reported in only three European studies. Indoor sources are the major contributor to (non-occupational) exposure. While its central tendencies fall well below guideline levels relevant to acute health impacts, several studies have reported maximum concentrations exceeding 100 μg m−3, far above guideline levels. Using current but draft estimates of cancer risks, naphthalene is a major environmental risk driver, with typical individual risk levels in the 10−4 range, which is high and notable given that millions of individuals are exposed. Several factors influence indoor and outdoor concentrations, but the literature is inconsistent on their effects. Further investigation is needed to better characterize naphthalene’s sources and

Responses of Tabanidae (Diptera) to canopy traps baited with 4-methylphenol, 3-isopropylphenol, and naphthalene.

PubMed

Krcmar, Stjepan

2007-12-01

The attraction of female tabanids to unbaited and single-baited canopy traps using 4-methylphenol, 3-isopropylphenol, and naphthalene was studied in three forest localities in eastern Croatia. Tabanids were collected in a significantly higher number in traps baited with these chemicals compared to unbaited control traps. The number of females of Tabanus bromius, Tabanus sudeticus, Tabanus tergestinus, Hybomitra ciureai, Haematopota pluvialis, and Tabanus maculicornis collected from 4-methylphenol baited canopy traps and traps baited with other attractants differed significantly. A total of 89.0% of tabanids collected belonged to these six species. The response of the other species to used chemicals was not analyzed because of small sample sizes. Moreover, the results with 3-isopropylphenol and naphthalene are very similar and not significant for some tabanids. Tabanus bromius was the most abundant species with 48.4% in the sample collected by canopy traps. Finally, the 4-methylphenol baited canopy traps collected 16 times more tabanids than unbaited traps, while 3-isopropylphenol and naphthalene baited traps collected 3.5 and 2 times as many tabanids, respectively, than unbaited traps. Also, 4-methylphenol appeared to be a very effective attractant for Lucilia caesar (Calliphoridae), Sarcophaga carnaria (Sarcophagidae), and Musca domestica (Muscidae).

Adsorptive removal of naphthalene induced by structurally different Gemini surfactants in a soil-water system.

PubMed

Wei, Jia; Li, Jun; Huang, Guohe; Wang, Xiujie; Chen, Guanghui; Zhao, Baihang

2016-09-01

A new generation of surfactant, Gemini surfactants, have been synthesized and have attracted the attention of various industrial and academic research groups. This study focused on the use of symmetric and dissymmetric quaternary ammonium Gemini surfactants to immobilize naphthalene onto soil particles, and is used as an example of an innovative application to remove HOC in situ using the surfactant-enhanced sorption zone. The sorption capacity of modified soils by Gemini surfactant and natural soils was compared and the naphthalene sorption efficiency, in the absence and presence of Gemini surfactants with different alkyl chain lengths, was investigated in the soil-water system. The results have shown that the increased added Gemini surfactant formed admicelles at the interface of soil/water having superior capability to retard contaminant. Symmetric and dissymmetric Gemini surfactants have opposite effect on the aspect of removing of PAH attributing to their solubilization and sorption behavior in soil-water system. Compared with the natural soil, sorption of naphthalene by Gemini-modified soil is noticeably enhanced following the order of C12-2-16 < C12-2-12 < C12-2-8. However, the symmetric Gemini surfactant C12-2-12 is the optimized one for in situ barrier remediation, which is not only has relative high retention ability but also low dosage.

40 CFR 61.134 - Standard: Naphthalene processing, final coolers, and final-cooler cooling towers.

Code of Federal Regulations, 2010 CFR

2010-07-01

... POLLUTANTS National Emission Standard for Benzene Emissions from Coke By-Product Recovery Plants § 61.134... are allowed from naphthalene processing, final coolers and final-cooler cooling towers at coke by-product recovery plants. ...

Ultraviolet Irradiation of Naphthalene in H2O Ice: Implications for Meteorites and Biogenesis

NASA Technical Reports Server (NTRS)

Bernstein, Max P.; Dworkin, Jason; Sandford, Scott A.; Allamandola, Louis J.; DeVincenzi, Donald L. (Technical Monitor)

2000-01-01

The polycyclic aromatic hydrocarbon (PAH) naphthalene was exposed to ultraviolet radiation in H2O ice under astrophysical conditions, and the products were analyzed using infrared spectroscopy and high performance liquid chromatography. As we found in our earlier studies on the photoprocessing of coronene in H2O ice, aromatic alcohols and ketones (quinones) were formed. The regiochemistry of the reactions is described and leads to specific predictions of the relative abundances of various oxidized naphthalenes that should exist in meteorites if interstellar ice photochemistry influenced their aromatic inventory. Since oxidized PAHs are present in carbon-rich meteorites and interplanetary dust particles (IDPs), and ubiquitous in and fundamental to biochemistry, the delivery of such extraterrestrial molecules to the early Earth may have played a role in the origin and evolution of life.

Nearly Perfect Triplet-Triplet Energy Transfer from Wannier Excitons to Naphthalene in Organic-Inorganic Hybrid Quantum-Well Materials

NASA Astrophysics Data System (ADS)

Ema, K.; Inomata, M.; Kato, Y.; Kunugita, H.; Era, M.

2008-06-01

We report the observation of extremely efficient energy transfer (greater than 99%) in an organic-inorganic hybrid quantum-well structure consisting of perovskite-type lead bromide well layers and naphthalene-linked ammonium barrier layers. Time-resolved photoluminescence measurements confirm that the transfer is triplet-triplet Dexter-type energy transfer from Wannier excitons in the inorganic well to the triplet state of naphthalene molecules in the organic barrier. Using measurements in the 10 300 K temperature range, we also investigated the temperature dependence of the energy transfer.

Predicting chromatin architecture from models of polymer physics.

PubMed

Bianco, Simona; Chiariello, Andrea M; Annunziatella, Carlo; Esposito, Andrea; Nicodemi, Mario

2017-03-01

We review the picture of chromatin large-scale 3D organization emerging from the analysis of Hi-C data and polymer modeling. In higher mammals, Hi-C contact maps reveal a complex higher-order organization, extending from the sub-Mb to chromosomal scales, hierarchically folded in a structure of domains-within-domains (metaTADs). The domain folding hierarchy is partially conserved throughout differentiation, and deeply correlated to epigenomic features. Rearrangements in the metaTAD topology relate to gene expression modifications: in particular, in neuronal differentiation models, topologically associated domains (TADs) tend to have coherent expression changes within architecturally conserved metaTAD niches. To identify the nature of architectural domains and their molecular determinants within a principled approach, we discuss models based on polymer physics. We show that basic concepts of interacting polymer physics explain chromatin spatial organization across chromosomal scales and cell types. The 3D structure of genomic loci can be derived with high accuracy and its molecular determinants identified by crossing information with epigenomic databases. In particular, we illustrate the case of the Sox9 locus, linked to human congenital disorders. The model in-silico predictions on the effects of genomic rearrangements are confirmed by available 5C data. That can help establishing new diagnostic tools for diseases linked to chromatin mis-folding, such as congenital disorders and cancer.

A thermo-chemo-mechanically coupled constitutive model for curing of glassy polymers

NASA Astrophysics Data System (ADS)

Sain, Trisha; Loeffel, Kaspar; Chester, Shawn

2018-07-01

Curing of a polymer is the process through which a polymer liquid transitions into a solid polymer, capable of bearing mechanical loads. The curing process is a coupled thermo-chemo-mechanical conversion process which requires a thorough understanding of the system behavior to predict the cure dependent mechanical behavior of the solid polymer. In this paper, a thermodynamically consistent, frame indifferent, thermo-chemo-mechanically coupled continuum level constitutive framework is proposed for thermally cured glassy polymers. The constitutive framework considers the thermodynamics of chemical reactions, as well as the material behavior for a glassy polymer. A stress-free intermediate configuration is introduced within a finite deformation setting to capture the formation of the network in a stress-free configuration. This work considers a definition for the degree of cure based on the chemistry of the curing reactions. A simplified version of the proposed model has been numerically implemented, and simulations are used to understand the capabilities of the model and framework.

Enumeration method for tree-like chemical compounds with benzene rings and naphthalene rings by breadth-first search order.

PubMed

Jindalertudomdee, Jira; Hayashida, Morihiro; Zhao, Yang; Akutsu, Tatsuya

2016-03-01

Drug discovery and design are important research fields in bioinformatics. Enumeration of chemical compounds is essential not only for the purpose, but also for analysis of chemical space and structure elucidation. In our previous study, we developed enumeration methods BfsSimEnum and BfsMulEnum for tree-like chemical compounds using a tree-structure to represent a chemical compound, which is limited to acyclic chemical compounds only. In this paper, we extend the methods, and develop BfsBenNaphEnum that can enumerate tree-like chemical compounds containing benzene rings and naphthalene rings, which include benzene isomers and naphthalene isomers such as ortho, meta, and para, by treating a benzene ring as an atom with valence six, instead of a ring of six carbon atoms, and treating a naphthalene ring as two benzene rings having a special bond. We compare our method with MOLGEN 5.0, which is a well-known general purpose structure generator, to enumerate chemical structures from a set of chemical formulas in terms of the number of enumerated structures and the computational time. The result suggests that our proposed method can reduce the computational time efficiently. We propose the enumeration method BfsBenNaphEnum for tree-like chemical compounds containing benzene rings and naphthalene rings as cyclic structures. BfsBenNaphEnum was from 50 times to 5,000,000 times faster than MOLGEN 5.0 for instances with 8 to 14 carbon atoms in our experiments.

High Strain Rate Deformation Modeling of a Polymer Matrix Composite. Part 1; Matrix Constitutive Equations

NASA Technical Reports Server (NTRS)

Goldberg, Robert K.; Stouffer, Donald C.

1998-01-01

Recently applications have exposed polymer matrix composite materials to very high strain rate loading conditions, requiring an ability to understand and predict the material behavior under these extreme conditions. In this first paper of a two part report, background information is presented, along with the constitutive equations which will be used to model the rate dependent nonlinear deformation response of the polymer matrix. Strain rate dependent inelastic constitutive models which were originally developed to model the viscoplastic deformation of metals have been adapted to model the nonlinear viscoelastic deformation of polymers. The modified equations were correlated by analyzing the tensile/ compressive response of both 977-2 toughened epoxy matrix and PEEK thermoplastic matrix over a variety of strain rates. For the cases examined, the modified constitutive equations appear to do an adequate job of modeling the polymer deformation response. A second follow-up paper will describe the implementation of the polymer deformation model into a composite micromechanical model, to allow for the modeling of the nonlinear, rate dependent deformation response of polymer matrix composites.

Doped Tricalcium Phosphate Scaffolds by Thermal Decomposition of Naphthalene: Mechanical Properties and In vivo Osteogenesis in a Rabbit Femur Model

PubMed Central

Ke, Dongxu; Dernell, William; Bandyopadhyay, Amit; Bose, Susmita

2015-01-01

Tricalcium phosphate (TCP) is a bioceramic that is widely used in orthopedic and dental applications. TCP structures show excellent biocompatibility as well as biodegradability. In this study, porous β-TCP scaffolds were prepared by thermal decomposition of naphthalene. Scaffolds with 57.64 ± 3.54 % density and a maximum pore size around 100 μm were fabricated via removing 30% naphthalene at 1150°C. The compressive strength for these scaffolds was 32.85 ± 1.41 MPa. Furthermore, by mixing 1 wt % SrO and 0.5 wt % SiO2, pore interconnectivity improved, but the compressive strength decreased to 22.40 ± 2.70 MPa. However, after addition of polycaprolactone (PCL) coating layers, the compressive strength of doped scaffolds increased to 29.57 ± 3.77 MPa. Porous scaffolds were implanted in rabbit femur defects to evaluate their biological property. The addition of dopants triggered osteoinduction by enhancing osteoid formation, osteocalcin expression and bone regeneration, especially at the interface of the scaffold and host bone. This study showed processing flexibility to make interconnected porous scaffolds with different pore size and volume fraction porosity with high compressive mechanical strength and better bioactivity. Results show that SrO/SiO2 doped porous TCP scaffolds have excellent potential to be used in bone tissue engineering applications. PMID:25504889

The reductive aromatization of naphthalene diimide: a versatile platform for 2,7-diazapyrenes.

PubMed

Nakazato, Takumi; Kamatsuka, Takuto; Inoue, Junichi; Sakurai, Tsuneaki; Seki, Shu; Shinokubo, Hiroshi; Miyake, Yoshihiro

2018-05-17

The reductive aromatization of naphthalene diimide provides tetrapivaloxy-2,7-diazapyrene, which serves as a versatile platform toward peripherally substituted 2,7-diazapyrenes. Time-resolved microwave conductivity measurements demonstrated that the intrinsic electron mobility of 2,7-diazapyrene is significantly higher than that of the corresponding pyrene.

Electronic absorption spectra of hydrogenated protonated naphthalene and proflavine

NASA Astrophysics Data System (ADS)

Bonaca, A.; Bilalbegović, G.

2011-09-01

We study hydrogenated cations of two polycyclic hydrocarbon molecules as models of hydrogenated organic species that form in the interstellar medium. Optical spectra of the hydrogenated naphthalene cation Hn-C10H+8 for n= 1, 2 and 10, as well as the astrobiologically interesting hydrogenated proflavine cation Hn-C13H11N+3 for n= 1 and 14, are calculated. The pseudopotential time-dependent density functional theory is used. It is found that the fully hydrogenated proflavine cation H14-C13H11N+3 shows a broad spectrum in which the positions of individual lines are almost lost. The positions, shapes and intensities of lines change in hydronaphthalene and hydroproflavine cations, showing that hydrogen additions induce substantially different optical spectra in comparison with base polycyclic hydrocarbon cations. One calculated line in the visible spectrum of H10-C10H+8 and one in the visible spectrum of H-C13H11N+3 are close to the measured diffuse interstellar bands. We also present the positions of near-ultraviolet lines.

EFFECT OF PH AND CONCENTRATION ON THE TRANSPORT OF NAPHTHALENE IN SATURATED AQUIFER MEDIA

EPA Science Inventory

Sorption is one of the primary mechanisms for retarding the movement of organic contaminants in groundwater. Sorption of hydrophobic compounds such as toluene, naphthalene, and DDT is generally assumed to be linearly proportional to solution phase concentration. In the present re...

Modular-based multiscale modeling on viscoelasticity of polymer nanocomposites

NASA Astrophysics Data System (ADS)

Li, Ying; Liu, Zeliang; Jia, Zheng; Liu, Wing Kam; Aldousari, Saad M.; Hedia, Hassan S.; Asiri, Saeed A.

2017-02-01

Polymer nanocomposites have been envisioned as advanced materials for improving the mechanical performance of neat polymers used in aerospace, petrochemical, environment and energy industries. With the filler size approaching the nanoscale, composite materials tend to demonstrate remarkable thermomechanical properties, even with addition of a small amount of fillers. These observations confront the classical composite theories and are usually attributed to the high surface-area-to-volume-ratio of the fillers, which can introduce strong nanoscale interfacial effect and relevant long-range perturbation on polymer chain dynamics. Despite decades of research aimed at understanding interfacial effect and improving the mechanical performance of composite materials, it is not currently possible to accurately predict the mechanical properties of polymer nanocomposites directly from their molecular constituents. To overcome this challenge, different theoretical, experimental and computational schemes will be used to uncover the key physical mechanisms at the relevant spatial and temporal scales for predicting and tuning constitutive behaviors in silico, thereby establishing a bottom-up virtual design principle to achieve unprecedented mechanical performance of nanocomposites. A modular-based multiscale modeling approach for viscoelasticity of polymer nanocomposites has been proposed and discussed in this study, including four modules: (A) neat polymer toolbox; (B) interphase toolbox; (C) microstructural toolbox and (D) homogenization toolbox. Integrating these modules together, macroscopic viscoelasticity of polymer nanocomposites could be directly predicted from their molecular constituents. This will maximize the computational ability to design novel polymer composites with advanced performance. More importantly, elucidating the viscoelasticity of polymer nanocomposites through fundamental studies is a critical step to generate an integrated computational material

A modified dynamical model of drying process of polymer blend solution coated on a flat substrate

NASA Astrophysics Data System (ADS)

Kagami, Hiroyuki

2008-05-01

We have proposed and modified a model of drying process of polymer solution coated on a flat substrate for flat polymer film fabrication. And for example numerical simulation of the model reproduces a typical thickness profile of the polymer film formed after drying. Then we have clarified dependence of distribution of polymer molecules on a flat substrate on a various parameters based on analysis of numerical simulations. Then we drove nonlinear equations of drying process from the dynamical model and the fruits were reported. The subject of above studies was limited to solution having one kind of solute though the model could essentially deal with solution having some kinds of solutes. But nowadays discussion of drying process of a solution having some kinds of solutes is needed because drying process of solution having some kinds of solutes appears in many industrial scenes. Polymer blend solution is one instance. And typical resist consists of a few kinds of polymers. Then we introduced a dynamical model of drying process of polymer blend solution coated on a flat substrate and results of numerical simulations of the dynamical model. But above model was the simplest one. In this study, we modify above dynamical model of drying process of polymer blend solution adding effects that some parameters change with time as functions of some variables to it. Then we consider essence of drying process of polymer blend solution through comparison between results of numerical simulations of the modified model and those of the former model.

Development of Methods for Sampling and Analysis of Polychlorinated Naphthalenes in Ambient Air

ERIC Educational Resources Information Center

Erickson, Mitchell D.; And Others

1978-01-01

The procedure and sampler described permits detection of less than 50pg of one polychlorinated naphthalene (PCN) isomer. The method uses gas chromatography-mass spectrometry. The PCNs are collected on a glass fiber filter and two polyurethane foam plugs and extracted with toluene at 25 degrees Celsius. (BB)

Quantitative photoabsorption and fluorescence spectroscopy of benzene, naphthalene, and some derivatives at 106-295 nm

NASA Technical Reports Server (NTRS)

Suto, Masako; Wang, Xiuyan; Shan, Jun; Lee, L. C.

1992-01-01

Photoabsorption and fluorescence cross sections of benzene, (o-, m-, p-) xylenes, naphthalene, 1-methylnaphthalene, and 2-ethylnaphthalene in the gas phase are measured at 106-295 nm using synchrotron radiation as a light source. Fluorescences are observed from the photoexcitation of benzene and xylenes at 230-280 nm and from naphthalene and its derivatives at 190-295 nm. The absolute fluorescence cross section is determined by calibration with respect to the emission intensity of the NO(A-X) system, for which the fluorescence quantum yield is equal to 1. To cross-check the current calibration method, the quantum yield of the SO2(C-X) system at 220-230 nm was measured since it is about equal to 1. The current quantum-yield data are compared with previously published values measured by different methods.

The effect of chlorpyrifos-oxon and other xenobiotics on the human cytochrome P450-dependent metabolism of naphthalene and deet.

PubMed

Cho, Taehyeon M; Rose, Randy L; Hodgson, Ernest

2007-01-01

Chlorpyrifos-oxon (CPO), a metabolite of chlorpyrifos, is a potent inhibitor of acetylcholinesterase and, although the neurotoxicological impact of this organophosphorus compound has been broadly studied both in vitro and in vivo, there are few studies of metabolic interactions of CPO with other xenobiotics. CPO significantly activated the production of 1-naphthol (5-fold), 2-naphthol (10-fold), trans-1,2-dihydro-1,2-naphthalenediol (1.5-fold), and 1,4-naphthoquinone from naphthalene by human liver microsomes (HLM). It was further demonstrated that the production of naphthalene metabolites by CYP2C8, 2C9*(1), 2C19, 2D6*(1), 3A4, 3A5, and 3A7 was activated by CPO, while the production of naphthalene metabolites by CYP1A1, 1A2, 1B1, and 2B6 was inhibited by CPO. CPO inhibited CYP1A2 production of naphthalene metabolites, while activating their production by CYP3A4. Similarly, CPO inhibited the production of N,N-diethyl-m-hydroxymethylbenzamide (BALC) from DEET by human liver microsomes, but activated the production of N-ethyl-m-toluamide (ET) from this substrate. CYP2B6, the most efficient isoform for BALC production, was inhibited by CPO, while CYP3A4, the most efficient isoform for ET production, was activated by CPO. CPO inhibited CYP2B6 production of both BALC and ET from DEET, but activated CYP3A4 production of ET, while inhibiting CYP3A4 BALC production. CPO appears to facilitate the binding of naphthalene to CYP3A4. This metabolic activation is independent of cytochrome b5, suggesting that activation of CYP3A4 by CPO is associated with a conformational change of the isoform rather than facilitating electron transfer.

Analytical Modeling of the High Strain Rate Deformation of Polymer Matrix Composites

NASA Technical Reports Server (NTRS)

Goldberg, Robert K.; Roberts, Gary D.; Gilat, Amos

2003-01-01

The results presented here are part of an ongoing research program to develop strain rate dependent deformation and failure models for the analysis of polymer matrix composites subject to high strain rate impact loads. State variable constitutive equations originally developed for metals have been modified in order to model the nonlinear, strain rate dependent deformation of polymeric matrix materials. To account for the effects of hydrostatic stresses, which are significant in polymers, the classical 5 plasticity theory definitions of effective stress and effective plastic strain are modified by applying variations of the Drucker-Prager yield criterion. To verify the revised formulation, the shear and tensile deformation of a representative toughened epoxy is analyzed across a wide range of strain rates (from quasi-static to high strain rates) and the results are compared to experimentally obtained values. For the analyzed polymers, both the tensile and shear stress-strain curves computed using the analytical model correlate well with values obtained through experimental tests. The polymer constitutive equations are implemented within a strength of materials based micromechanics method to predict the nonlinear, strain rate dependent deformation of polymer matrix composites. In the micromechanics, the unit cell is divided up into a number of independently analyzed slices, and laminate theory is then applied to obtain the effective deformation of the unit cell. The composite mechanics are verified by analyzing the deformation of a representative polymer matrix composite (composed using the representative polymer analyzed for the correlation of the polymer constitutive equations) for several fiber orientation angles across a variety of strain rates. The computed values compare favorably to experimentally obtained results.

Interaction of multiple biomimetic antimicrobial polymers with model bacterial membranes

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

Baul, Upayan, E-mail: upayanb@imsc.res.in; Vemparala, Satyavani, E-mail: vani@imsc.res.in; Kuroda, Kenichi, E-mail: kkuroda@umich.edu

Using atomistic molecular dynamics simulations, interaction of multiple synthetic random copolymers based on methacrylates on prototypical bacterial membranes is investigated. The simulations show that the cationic polymers form a micellar aggregate in water phase and the aggregate, when interacting with the bacterial membrane, induces clustering of oppositely charged anionic lipid molecules to form clusters and enhances ordering of lipid chains. The model bacterial membrane, consequently, develops lateral inhomogeneity in membrane thickness profile compared to polymer-free system. The individual polymers in the aggregate are released into the bacterial membrane in a phased manner and the simulations suggest that the most probablemore » location of the partitioned polymers is near the 1-palmitoyl-2-oleoyl-phosphatidylglycerol (POPG) clusters. The partitioned polymers preferentially adopt facially amphiphilic conformations at lipid-water interface, despite lacking intrinsic secondary structures such as α-helix or β-sheet found in naturally occurring antimicrobial peptides.« less

Synthesis, photophysical, and electrochemical properties of wide band gap tetraphenylsilane-carbazole derivatives: Effect of the substitution position and naphthalene side chain

NASA Astrophysics Data System (ADS)

Ho, Kar Wei; Ariffin, A.

2016-12-01

Four tetraphenylsilane-carbazole derivatives with wide bandgaps (3.38-3.55 eV) were synthesized. The effects of the substitution position and of the presence of naphthalene groups on the photophysical, electrochemical and thermal properties were investigated. The derivatives exhibited maximum absorption peaks ranging from 293 to 304 nm and maximum emission peaks ranging from 347 to 386 nm. Changing the carbazole substitution position on the tetraphenylsilane did not significantly change the photophysical and electrochemical properties. However, p-substituted compounds exhibited higher glass transition temperatures than m-substituted compounds. Naphthalene groups with bulky structures had extended the conjugation lengths that red-shifted both the absorption and emission spectra. The LUMO level was decreased, which reduced the optical bandgap and triplet energy level. However, the naphthalene groups significantly improved the thermal stability by increasing the glass transition temperature of the compounds.

Monte Carlo modeling of atomic oxygen attack of polymers with protective coatings on LDEF

NASA Technical Reports Server (NTRS)

Banks, Bruce A.; Degroh, Kim K.; Auer, Bruce M.; Gebauer, Linda; Edwards, Jonathan L.

1993-01-01

Characterization of the behavior of atomic oxygen interaction with materials on the Long Duration Exposure Facility (LDEF) assists in understanding of the mechanisms involved. Thus the reliability of predicting in-space durability of materials based on ground laboratory testing should be improved. A computational model which simulates atomic oxygen interaction with protected polymers was developed using Monte Carlo techniques. Through the use of an assumed mechanistic behavior of atomic oxygen interaction based on in-space atomic oxygen erosion of unprotected polymers and ground laboratory atomic oxygen interaction with protected polymers, prediction of atomic oxygen interaction with protected polymers on LDEF was accomplished. However, the results of these predictions are not consistent with the observed LDEF results at defect sites in protected polymers. Improved agreement between observed LDEF results and predicted Monte Carlo modeling can be achieved by modifying of the atomic oxygen interactive assumptions used in the model. LDEF atomic oxygen undercutting results, modeling assumptions, and implications are presented.

Models for Models: An Introduction to Polymer Models Employing Simple Analogies

NASA Astrophysics Data System (ADS)

Tarazona, M. Pilar; Saiz, Enrique

1998-11-01

An introduction to the most common models used in the calculations of conformational properties of polymers, ranging from the freely jointed chain approximation to Monte Carlo or molecular dynamics methods, is presented. Mathematical formalism is avoided and simple analogies, such as human chains, gases, opinion polls, or marketing strategies, are used to explain the different models presented. A second goal of the paper is to teach students how models required for the interpretation of a system can be elaborated, starting with the simplest model and introducing successive improvements until the refinements become so sophisticated that it is much better to use an alternative approach.

Accurate prediction of the refractive index of polymers using first principles and data modeling

NASA Astrophysics Data System (ADS)

Afzal, Mohammad Atif Faiz; Cheng, Chong; Hachmann, Johannes

Organic polymers with a high refractive index (RI) have recently attracted considerable interest due to their potential application in optical and optoelectronic devices. The ability to tailor the molecular structure of polymers is the key to increasing the accessible RI values. Our work concerns the creation of predictive in silico models for the optical properties of organic polymers, the screening of large-scale candidate libraries, and the mining of the resulting data to extract the underlying design principles that govern their performance. This work was set up to guide our experimentalist partners and allow them to target the most promising candidates. Our model is based on the Lorentz-Lorenz equation and thus includes the polarizability and number density values for each candidate. For the former, we performed a detailed benchmark study of different density functionals, basis sets, and the extrapolation scheme towards the polymer limit. For the number density we devised an exceedingly efficient machine learning approach to correlate the polymer structure and the packing fraction in the bulk material. We validated the proposed RI model against the experimentally known RI values of 112 polymers. We could show that the proposed combination of physical and data modeling is both successful and highly economical to characterize a wide range of organic polymers, which is a prerequisite for virtual high-throughput screening.

Polymer Crowding in Confined Polymer-Nanoparticle Mixtures

NASA Astrophysics Data System (ADS)

Davis, Wyatt J.; Denton, Alan R.

Crowding can influence the conformations and thus functionality of macromolecules in quasi-two-dimensional environments, such as DNA or proteins confined to a cell membrane. We explore such crowding within a model of polymers as penetrable ellipses, whose shapes are governed by the statistics of a 2D random walk. The principal radii of the polymers fluctuate according to probability distributions of the eigenvalues of the gyration tensor. Within this coarse-grained model, we perform Monte Carlo simulations of mixtures of polymers and hard nanodisks, including trial changes in polymer conformation (shape and orientation). Penetration of polymers by nanodisks is incorporated with a free energy cost predicted by polymer field theory. Over ranges of size ratio and nanodisk density, we analyze the influence of crowding on polymer shape by computing eigenvalue distributions, mean radius of gyration, and mean asphericity of the polymer. We compare results with predictions of free-volume theory and with corresponding results in three dimensions. Our approach may help to interpret recent (and motivate future) experimental studies of biopolymers interacting with cell membranes, with relevance for drug delivery and gene therapy. This work was supported by the National Science Foundation under Grant No. DMR-1106331.

Fluorescence decay of naphthalene studied in an electrostatic storage ring, the Mini-Ring

NASA Astrophysics Data System (ADS)

Martin, S.; Matsumoto, J.; Kono, N.; Ji, M.-C.; Brédy, R.; Bernard, J.; Cassimi, A.; Chen, L.

2017-10-01

The cooling of naphthalene cations (C10H8)+ has been studied in a compact electrostatic ion storage ring, the Mini-Ring. A nano second laser pulse of 532 nm (2.33 eV) was used to probe the internal energy distribution every millisecond during the storage time up to 5 ms. The evolution of the internal energy distribution of the stored ions was simulated with a model taking into account the dissociation and the radiative decay processes. Calculated decay curves were fitted to the corresponding laser induced neutral decays. For a laser power of 200 μJ/pulse, a good agreement between experiment and modeling was found using an initial Gaussian energy distribution centered to 5.9 eV and a fluorescence decay rate varying from 200 to 300 s-1 in the energy range from 6 to 7 eV. This fast decay was attributed to the delayed Poincaré fluorescence process.

Accurate coarse-grained models for mixtures of colloids and linear polymers under good-solvent conditions

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

D’Adamo, Giuseppe, E-mail: giuseppe.dadamo@sissa.it; Pelissetto, Andrea, E-mail: andrea.pelissetto@roma1.infn.it; Pierleoni, Carlo, E-mail: carlo.pierleoni@aquila.infn.it

2014-12-28

A coarse-graining strategy, previously developed for polymer solutions, is extended here to mixtures of linear polymers and hard-sphere colloids. In this approach, groups of monomers are mapped onto a single pseudoatom (a blob) and the effective blob-blob interactions are obtained by requiring the model to reproduce some large-scale structural properties in the zero-density limit. We show that an accurate parametrization of the polymer-colloid interactions is obtained by simply introducing pair potentials between blobs and colloids. For the coarse-grained (CG) model in which polymers are modelled as four-blob chains (tetramers), the pair potentials are determined by means of the iterative Boltzmannmore » inversion scheme, taking full-monomer (FM) pair correlation functions at zero-density as targets. For a larger number n of blobs, pair potentials are determined by using a simple transferability assumption based on the polymer self-similarity. We validate the model by comparing its predictions with full-monomer results for the interfacial properties of polymer solutions in the presence of a single colloid and for thermodynamic and structural properties in the homogeneous phase at finite polymer and colloid density. The tetramer model is quite accurate for q ≲ 1 (q=R{sup ^}{sub g}/R{sub c}, where R{sup ^}{sub g} is the zero-density polymer radius of gyration and R{sub c} is the colloid radius) and reasonably good also for q = 2. For q = 2, an accurate coarse-grained description is obtained by using the n = 10 blob model. We also compare our results with those obtained by using single-blob models with state-dependent potentials.« less

Bis(azido) compounds of Pd and Pt with bulky phosphine ligands (dppn=1,8-bis(diphenylphosphino)naphthalene, dppf=1,1‧-bis(diphenylphosphino)ferrocene, 1-dpn=1-diphenylphosphino-naphthalene): Preparation, structures, and reactivity toward isocyanides

NASA Astrophysics Data System (ADS)

Huh, Hyun Sue; Lee, Yeon Kyoung; Lee, Soon W.

2006-05-01

Pd-bis(azido) compounds [Pd(dppn)(N 3) 2] and [Pd(dppf)(N 3) 2], which contain bulky chelating bis(phosphine) ligands (dppn=1,8-bis(diphenylphosphino)naphthalene, dppf=1,1'-bis(diphenylphosphino)ferrocene), were prepared from the corresponding chlorides and NaN 3. We also prepared the Pt-bis(azido) compound [Pt(1-dpn)(SMe 2)(N 3) 2] containing a bulky monodentate phosphine (1-dpn=1-diphenylphosphino-naphthalene). All these compounds underwent [2+3] cycloaddition with isocyanides (R-NC, R=cyclohexyl, tert-butyl, 2,6-dimethylphenyl) to convert azido ligands to five-membered, C-coordinated tetrazolate rings. In addition, we observed the [Pd(dppn)Cl 2]-mediated C-C coupling of PhC tbnd6 CH to generate the η 2-PhC tbnd6 C-C tbnd6 CPh ligand. All compounds have been structurally characterized by X-ray diffraction.

Linear and Non-Linear Thermal Lens Signal of the Fifth C-H Vibrational Overtone of Naphthalene in Liquid Solutions of Hexane

NASA Astrophysics Data System (ADS)

Manzanares, Carlos; Diaz, Marlon; Barton, Ann; Nyaupane, Parashu R.

2017-06-01

The thermal lens technique is applied to vibrational overtone spectroscopy of solutions of naphthalene in n-hexane. The pump and probe thermal lens technique is found to be very sensitive for detecting samples of low composition (ppm) in transparent solvents. In this experiment two different probe lasers: one at 488 nm and another 568 nm were used. The C-H fifth vibrational overtone spectrum of benzene is detected at room temperature for different concentrations. A plot of normalized integrated intensity as a function of concentration of naphthalene in solution reveals a non-linear behavior at low concentrations when using the 488 nm probe and a linear behavior over the entire range of concentrations when using the 568 nm probe. The non-linearity cannot be explained assuming solvent enhancement at low concentrations. A two color absorption model that includes the simultaneous absorption of the pump and probe lasers could explain the enhanced magnitude and the non-linear behavior of the thermal lens signal. Other possible mechanisms will also be discussed.

High Strain Rate Deformation Modeling of a Polymer Matrix Composite. Part 2; Composite Micromechanical Model

NASA Technical Reports Server (NTRS)

Goldberg, Robert K.; Stouffer, Donald C.

1998-01-01

Recently applications have exposed polymer matrix composite materials to very high strain rate loading conditions, requiring an ability to understand and predict the material behavior under these extreme conditions. In this second paper of a two part report, a three-dimensional composite micromechanical model is described which allows for the analysis of the rate dependent, nonlinear deformation response of a polymer matrix composite. Strain rate dependent inelastic constitutive equations utilized to model the deformation response of a polymer are implemented within the micromechanics method. The deformation response of two representative laminated carbon fiber reinforced composite materials with varying fiber orientation has been predicted using the described technique. The predicted results compare favorably to both experimental values and the response predicted by the Generalized Method of Cells, a well-established micromechanics analysis method.

Suspensions of polymer-grafted nanoparticles with added polymers-Structure and effective pair-interactions.

PubMed

Chandran, Sivasurender; Saw, Shibu; Kandar, A K; Dasgupta, C; Sprung, M; Basu, J K

2015-08-28

We present the results of combined experimental and theoretical (molecular dynamics simulations and integral equation theory) studies of the structure and effective interactions of suspensions of polymer grafted nanoparticles (PGNPs) in the presence of linear polymers. Due to the absence of systematic experimental and theoretical studies of PGNPs, it is widely believed that the structure and effective interactions in such binary mixtures would be very similar to those of an analogous soft colloidal material-star polymers. In our study, polystyrene-grafted gold nanoparticles with functionality f = 70 were mixed with linear polystyrene (PS) of two different molecular weights for obtaining two PGNP:PS size ratios, ξ = 0.14 and 2.76 (where, ξ = Mg/Mm, Mg and Mm being the molecular weights of grafting and matrix polymers, respectively). The experimental structure factor of PGNPs could be modeled with an effective potential (Model-X), which has been found to be widely applicable for star polymers. Similarly, the structure factor of the blends with ξ = 0.14 could be modeled reasonably well, while the structure of blends with ξ = 2.76 could not be captured, especially for high density of added polymers. A model (Model-Y) for effective interactions between PGNPs in a melt of matrix polymers also failed to provide good agreement with the experimental data for samples with ξ = 2.76 and high density of added polymers. We tentatively attribute this anomaly in modeling the structure factor of blends with ξ = 2.76 to the questionable assumption of Model-X in describing the added polymers as star polymers with functionality 2, which gets manifested in both polymer-polymer and polymer-PGNP interactions especially at higher fractions of added polymers. The failure of Model-Y may be due to the neglect of possible many-body interactions among PGNPs mediated by matrix polymers when the fraction of added polymers is high. These observations point to the need for a new framework to

6-Substituted 3,4-dihydro-naphthalene-2-carboxylic acids: synthesis and structure-activity studies in a novel class of human 5alpha reductase inhibitors.

PubMed

Baston, Eckhard; Salem, Ola I A; Hartmann, Rolf W

2002-10-01

Novel 3,4-dihydro-naphthalene-2-carboxylic acids were synthesized and evaluated for 5alpha reductase inhibitory activity. This enzyme exists in two isoforms and is a pharmacological target for the treatment of benign prostatic hyperplasia, male pattern baldness and acne. In the present study non-steroidal compounds capable of mimicking the transition state of the steroidal substrates were prepared. The synthetic strategy for the preparation of compounds 1-6 consisted of triflation followed by subsequent Heck-type carboxylation or methoxy carbonylation for 6-phenyl-3,4-dihydronaphthalen-2(1H)-one 1c. A Negishi-type coupling reaction between 6-(trifluoro-methanesulfonyloxy)-3,4-dihydro-naphthalene-2-carboxylic acid methyl ester 7b and various aryl bromides led, after further transformations, to 6-substituted 3,4-dihydro-naphthalene-2-carboxylic acids 7-15. In a similar way the corresponding naphthalene-2-carboxylic acids 16 and 17 were obtained. The DU 145 cell line and prostate homogenates served as enzyme sources for the human type 1 and type 2 isozymes, whereas ventral prostate was employed to evaluate rat isozyme inhibitory potency. The most active inhibitors identified in this study were 6-[4-(N,N-dicyclohexylaminocarbonyl)phenyl]-3,4-dihydro-naphthalene-2-carboxylic acid (3) (IC50 = 0.09 microM, rat type 1), 6-[3-(N,N-dicyclohexylaminocarbonyl)phenyl]-3,4-dihydro-naphthalene-2-carboxylic acid (13) (IC50 = 0.75 microM, human type 2; IC50 = 0.81 microM, human type 1) and 6-[4-(N,N-diisopropylamino-carbonyl)phenyl]naphthalene-2-carboxylic acid (16) (IC50 = 0.2 microM, human type 2). The latter compound was shown to deactivate the enzyme in an uncompetitive manner (Ki = 90 nM; Km, Testosterone = 0.8-1.0 microM) similar to the steroidal inhibitor Epristeride. Select inhibitors (13 and 16) were tested in vivo using testosterone propionate-treated, juvenile, orchiectomized SD-rats. None of the compounds was active at a dose of 25 mg/kg. This result might in part be

Polymer damage mitigation---predictive lifetime models of polymer insulation degradation and biorenewable thermosets through cationic polymerization for self-healing applications

NASA Astrophysics Data System (ADS)

Hondred, Peter Raymond

Over the past 50 years, the industrial development and applications for polymers and polymer composites has become expansive. However, as with any young technology, the techniques for predicting material damage and resolving material failure are in need of continued development and refinement. This thesis work takes two approaches to polymer damage mitigation---material lifetime prediction and spontaneous damage repair through self-healing while incorporating bio-renewable feedstock. First, material lifetime prediction offers the benefit of identifying and isolating material failures before the effects of damage results in catastrophic failure. Second, self-healing provides a systematic approach to repairing damaged polymer composites, specifically in applications where a hands-on approach or removing the part from service are not feasible. With regard to lifetime prediction, we investigated three specific polymeric materials---polytetrafluoroethylene (PTFE), poly(ethylene-alt-tetrafluoroethylene) (ETFE), and Kapton. All three have been utilized extensively in the aerospace field as a wire insulation coating. Because of the vast amount of electrical wiring used in aerospace constructions and the potential for electrical and thermal failure, this work develops mathematical models for both the thermal degradation kinetics as well as a lifetime prediction model for electrothermal breakdown. Isoconversional kinetic methods, which plot activation energy as a function of the extent of degradation, present insight into the development each kinetic model. The models for PTFE, ETFE, and Kapton are one step, consecutive three-step, and competitive and consecutive five-step respectively. Statistical analysis shows that an nth order autocatalytic reaction best defined the reaction kinetics for each polymer's degradation. Self-healing polymers arrest crack propagation through the use of an imbedded adhesive that reacts when cracks form. This form of damage mitigation focuses on

Scale-Dependent Stiffness and Internal Tension of a Model Brush Polymer

NASA Astrophysics Data System (ADS)

Berezney, John P.; Marciel, Amanda B.; Schroeder, Charles M.; Saleh, Omar A.

2017-09-01

Bottle-brush polymers exhibit closely grafted side chains that interact by steric repulsion, thereby causing stiffening of the main polymer chain. We use single-molecule elasticity measurements of model brush polymers to quantify this effect. We find that stiffening is only significant on long length scales, with the main chain retaining flexibility on short scales. From the elasticity data, we extract an estimate of the internal tension generated by side-chain repulsion; this estimate is consistent with the predictions of blob-based scaling theories.

Multi-Length Scale-Enriched Continuum-Level Material Model for Kevlar-Fiber-Reinforced Polymer-Matrix Composites

DTIC Science & Technology

2012-08-03

is unlimited. Multi-Length Scale-Enriched Continuum-Level Material Model for Kevlar ®-Fiber-Reinforced Polymer-Matrix Composites The views, opinions...12211 Research Triangle Park, NC 27709-2211 ballistics, composites, Kevlar , material models, microstructural defects REPORT DOCUMENTATION PAGE 11... Kevlar ®-Fiber-Reinforced Polymer-Matrix Composites Report Title Fiber-reinforced polymer matrix composite materials display quite complex deformation

Mechanism of polymer drag reduction using a low-dimensional model.

PubMed

Roy, Anshuman; Morozov, Alexander; van Saarloos, Wim; Larson, Ronald G

2006-12-08

Using a retarded-motion expansion to describe the polymer stress, we derive a low-dimensional model to understand the effects of polymer elasticity on the self-sustaining process that maintains the coherent wavy streamwise vortical structures underlying wall-bounded turbulence. Our analysis shows that at small Weissenberg numbers, Wi, elasticity enhances the coherent structures. At higher Wi, however, polymer stresses suppress the streamwise vortices (rolls) by calming down the instability of the streaks that regenerates the rolls. We show that this behavior can be attributed to the nonmonotonic dependence of the biaxial extensional viscosity on Wi, and identify it as the key rheological property controlling drag reduction.

Effects of petroleum on adrenocortical activity and on hepatic naphthalene-metabolizing activity in mallard ducks

USGS Publications Warehouse

Gorsline, J.; Holmes, W.N.

1981-01-01

Unstressed mallard ducks (Anas platyrhychos), given uncontaminated food and maintained on a short photoperiod, show two daily maxima in plasma corticosterone concentration ([B]); one occurring early in the light phase and a second just before the onset of darkness. After one week of exposure to food containing 3% (v/w) South Louisiana crude oil, plasma [B] were significantly lowered throughout the day. Similar abrupt declines in plasma [B] also occurred during the first 10 days of exposure to food containing 1% and 0.5% crude oil. Although the plasma [B] in birds consuming food contaminated with 0.5% crude oil increased between 10 and 50 days of exposure, the concentration after 50 days was still lower than normal. During the same interval, normal plasma [B] were restored in birds consuming food containing 1% and 3% crude oil. Significant increases occurred in the naphthalene-metabolizing properties of hepatic microsomes prepared from birds acutely exposed to all levels of petroleum-contaminated food and elevated levels were sustained throughout the first 50 days of exposure. Birds given food containing 3% crude oil for more than 50 days, however, showed steady declines in hepatic naphthalene-metabolizing activity. After 500 days, the activity was similar to that found in contemporaneous controls. During the same interval, the plasma [B] increased until the levels were higher than normal after 500 days of exposure; at this time, an inverse relationship, similar to that seen during the first week of exposure to contaminated food, was once more established between plasma [B] and the concomitant hepatic naphthalene-metabolizing activity.

Development and characterization of a cell line from Pacific herring, Clupea harengus pallasi, sensitive to both naphthalene cytotoxicity and infection by viral hemorrhagic septicemia virus.

PubMed

Ganassin, R C; Sanders, S M; Kennedy, C J; Joyce, E M; Bols, N C

1999-01-01

A cell line, PHL, has been successfully established from newly hatched herring larvae. The cells are maintained in growth medium consisting of Leibovitz's L-15 supplemented with 15% fetal bovine serum (FBS), and have been cryopreserved and maintain viability after thawing. These cells retain a diploid karotype after 65 population doublings. PHL are susceptible to infection by the North American strain of viral hemorrhagic septicemia (VHS) virus, and are sensitive to the cytotoxic effects of naphthalene, a common environmental contaminant. Naphthalene is a component of crude and refined oil, and may be found in the marine environment following acute events such as oil spills. In addition, chronic sources of naphthalene contamination include offshore drilling and petroleum contamination from areas such as docks and marinas that have creosote-treated docks and pilings and also receive constant small inputs of petroleum products. This cell line should be useful for investigations of the toxicity of naphthalene and other petroleum components to juvenile herring. In addition, studies of the VHS virus will be facilitated by the availability of a susceptible cell line from an alternative species.

Constitutive Modeling of Piezoelectric Polymer Composites

NASA Technical Reports Server (NTRS)

Odegard, Gregory M.; Gates, Tom (Technical Monitor)

2003-01-01

A new modeling approach is proposed for predicting the bulk electromechanical properties of piezoelectric composites. The proposed model offers the same level of convenience as the well-known Mori-Tanaka method. In addition, it is shown to yield predicted properties that are, in most cases, more accurate or equally as accurate as the Mori-Tanaka scheme. In particular, the proposed method is used to determine the electromechanical properties of four piezoelectric polymer composite materials as a function of inclusion volume fraction. The predicted properties are compared to those calculated using the Mori-Tanaka and finite element methods.

Monte Carlo simulations of lattice models for single polymer systems

NASA Astrophysics Data System (ADS)

Hsu, Hsiao-Ping

2014-10-01

Single linear polymer chains in dilute solutions under good solvent conditions are studied by Monte Carlo simulations with the pruned-enriched Rosenbluth method up to the chain length N ˜ O(10^4). Based on the standard simple cubic lattice model (SCLM) with fixed bond length and the bond fluctuation model (BFM) with bond lengths in a range between 2 and sqrt{10}, we investigate the conformations of polymer chains described by self-avoiding walks on the simple cubic lattice, and by random walks and non-reversible random walks in the absence of excluded volume interactions. In addition to flexible chains, we also extend our study to semiflexible chains for different stiffness controlled by a bending potential. The persistence lengths of chains extracted from the orientational correlations are estimated for all cases. We show that chains based on the BFM are more flexible than those based on the SCLM for a fixed bending energy. The microscopic differences between these two lattice models are discussed and the theoretical predictions of scaling laws given in the literature are checked and verified. Our simulations clarify that a different mapping ratio between the coarse-grained models and the atomistically realistic description of polymers is required in a coarse-graining approach due to the different crossovers to the asymptotic behavior.

Modelling Polymer Deformation and Welding Behaviour during 3D Printing

NASA Astrophysics Data System (ADS)

McIlroy, Claire; Olmsted, Peter

2016-11-01

3D printing has the potential to transform manufacturing processes, yet improving the strength of printed parts, to equal that of traditionally-manufactured parts, remains an underlying issue. The most common method, fused deposition modelling, involves melting a thermoplastic, followed by layer-by-layer extrusion of the material to fabricate a three-dimensional object. The key to the ensuring strength at the weld between these layers is successful inter-diffusion. However, as the printed layer cools towards the glass transition temperature, the time available for diffusion is limited. In addition, the extrusion process significantly deforms the polymer micro-structure prior to welding and consequently affects how the polymers "re-entangle" across the weld. We have developed a simple model of the non-isothermal printing process to explore the effects that typical printing conditions and amorphous polymer rheology have on the ultimate weld structure. In particular, we incorporate both the stretch and orientation of the polymer using the Rolie-Poly constitutive equation to examine how the melt flows through the nozzle and is deposited onto the build plate. We then address how this deformation relaxes and contributes to the thickness and structure of the weld. National Institute for Standards and Technology (NIST) and Georgetown University.

Preparative separation and identification of novel subsidiary colors of the color additive D&C Red No. 33 (Acid Red 33) using spiral high-speed counter-current chromatography☆

PubMed Central

Weisz, Adrian; Ridge, Clark D.; Mazzola, Eugene P.; Ito, Yoichiro

2015-01-01

Three low-level subsidiary color impurities (A, B, and C) often present in batches of the color additive D&C Red No. 33 (R33, Acid Red 33, Colour Index No. 17200) were separated from a portion of R33 by spiral high-speed counter-current chromatography (HSCCC). The separation involved use of a very polar solvent system, 1-BuOH/5 mM aq. (NH4)2SO4. Addition of ammonium sulfate to the lower phase forced partition of the components into the upper phase, thereby eliminating the need to add a hydrophobic counterion as was previously required for separations of components from sulfonated dyes. The very polar solvent system used would not have been retained in a conventional multi-layer coil HSCCC instrument, but the spiral configuration enabled retention of the stationary phase, and thus, the separation was possible. A 1 g portion of R33 enriched in A, B, and C was separated using the upper phase of the solvent system as the mobile phase. The retention of the stationary phase was 38.1%, and the separation resulted in 4.8 mg of A of >90% purity, 18.3 mg of B of >85% purity, and 91 mg of C of 65–72% purity. A second separation of a portion of the C mixture resulted in 7 mg of C of >94% purity. The separated impurities were identified by high-resolution mass spectrometry and NMR spectroscopic techniques as follows: 5-amino-3-biphenyl-3-ylazo-4-hydroxy-naphthalene-2,7-disulfonic acid, A; 5-amino-4-hydroxy-6-phenyl-3-phenylazo-naphthalene-2,7-disulfonic acid, B; and 5-amino-4-hydroxy-3,6-bis-phenylazo-naphthalene-2,7-disulfonic acid, C. The isomers A and B are compounds reported for the first time. Application of the spiral HSCCC method resulted in the additional benefit of yielding 930 mg of the main component of R33, 5-amino-4-hydroxy-3-phenylazo-naphthalene-2,7-disulfonic acid, of >97% purity. PMID:25591404

Preparative separation and identification of novel subsidiary colors of the color additive D&C Red No. 33 (Acid Red 33) using spiral high-speed counter-current chromatography.

PubMed

Weisz, Adrian; Ridge, Clark D; Mazzola, Eugene P; Ito, Yoichiro

2015-02-06

Three low-level subsidiary color impurities (A, B, and C) often present in batches of the color additive D&C Red No. 33 (R33, Acid Red 33, Colour Index No. 17200) were separated from a portion of R33 by spiral high-speed counter-current chromatography (HSCCC). The separation involved use of a very polar solvent system, 1-BuOH/5mM aq. (NH4)2SO4. Addition of ammonium sulfate to the lower phase forced partition of the components into the upper phase, thereby eliminating the need to add a hydrophobic counterion as was previously required for separations of components from sulfonated dyes. The very polar solvent system used would not have been retained in a conventional multi-layer coil HSCCC instrument, but the spiral configuration enabled retention of the stationary phase, and thus, the separation was possible. A 1g portion of R33 enriched in A, B, and C was separated using the upper phase of the solvent system as the mobile phase. The retention of the stationary phase was 38.1%, and the separation resulted in 4.8 mg of A of >90% purity, 18.3mg of B of >85% purity, and 91 mg of C of 65-72% purity. A second separation of a portion of the C mixture resulted in 7 mg of C of >94% purity. The separated impurities were identified by high-resolution mass spectrometry and NMR spectroscopic techniques as follows: 5-amino-3-biphenyl-3-ylazo-4-hydroxy-naphthalene-2,7-disulfonic acid, A; 5-amino-4-hydroxy-6-phenyl-3-phenylazo-naphthalene-2,7-disulfonic acid, B; and 5-amino-4-hydroxy-3,6-bis-phenylazo-naphthalene-2,7-disulfonic acid, C. The isomers A and B are compounds reported for the first time. Application of the spiral HSCCC method resulted in the additional benefit of yielding 930 mg of the main component of R33, 5-amino-4-hydroxy-3-phenylazo-naphthalene-2,7-disulfonic acid, of >97% purity. Published by Elsevier B.V.

Property Enhancement Effects of Side-Chain-Type Naphthalene-Based Sulfonated Poly(arylene ether ketone) on Nafion Composite Membranes for Direct Methanol Fuel Cells.

PubMed

Wang, Baolong; Hong, Lihua; Li, Yunfeng; Zhao, Liang; Zhao, Chengji; Na, Hui

2017-09-20

Nafion/SNPAEK-x composite membranes were prepared by blending raw Nafion and synthesized side-chain-type naphthalene-based sulfonated poly(arylene ether ketone) with a sulfonation degree of 1.35 (SNPAEK-1.35). The incorporation of SNPAEK-1.35 polymer with ion exchange capacity (IEC) of 2.01 mequiv·g -1 into a Nafion matrix has the property enhancement effects, such as increasing IECs, improving proton conductivity, enhancing mechanical properties, reducing methanol crossover, and improving single cell performance of Nafion. Morphology studies show that Nafion/SNPAEK-x composite membranes exhibit a well-defined microphase separation structure depending on the contents of SNPAEK-1.35 polymer. Among them, Nafion/SNPAEK-7.5% with a bicontinuous morphology exhibits the best comprehensive properties. For example, it shows the highest proton conductivities of 0.092 S cm -1 at 25 °C and 0.163 S cm -1 at 80 °C, which are higher than those of recast Nafion with 0.073 S cm -1 at 25 °C and 0.133 S cm -1 at 80 °C, respectively. Nafion/SNPAEK-5.0% and Nafion/SNPAEK-7.5% membranes display an open circuit voltage of 0.77 V and a maximum power density of 47 mW cm -2 at 80 °C, which are much higher than those of recast Nafion of 0.63 V and 24 mW cm -2 under the same conditions. Nafion/SNPAEK-5.0% membrane also has comparable tensile strength (12.7 MPa) to recast Nafion (13.7 MPa), and higher Young's modulus (330 MPa) than that of recast Nafion (240 MPa). By combining their high proton conductivities, comparable mechanical properties, and good single cell performance, Nafion/SNPAEK-x composite membranes have the potential to be polymer electrolyte materials for direct methanol fuel cell applications.

Coding coarse grained polymer model for LAMMPS and its application to polymer crystallization

NASA Astrophysics Data System (ADS)

Luo, Chuanfu; Sommer, Jens-Uwe

2009-08-01

We present a patch code for LAMMPS to implement a coarse grained (CG) model of poly(vinyl alcohol) (PVA). LAMMPS is a powerful molecular dynamics (MD) simulator developed at Sandia National Laboratories. Our patch code implements tabulated angular potential and Lennard-Jones-9-6 (LJ96) style interaction for PVA. Benefited from the excellent parallel efficiency of LAMMPS, our patch code is suitable for large-scale simulations. This CG-PVA code is used to study polymer crystallization, which is a long-standing unsolved problem in polymer physics. By using parallel computing, cooling and heating processes for long chains are simulated. The results show that chain-folded structures resembling the lamellae of polymer crystals are formed during the cooling process. The evolution of the static structure factor during the crystallization transition indicates that long-range density order appears before local crystalline packing. This is consistent with some experimental observations by small/wide angle X-ray scattering (SAXS/WAXS). During the heating process, it is found that the crystalline regions are still growing until they are fully melted, which can be confirmed by the evolution both of the static structure factor and average stem length formed by the chains. This two-stage behavior indicates that melting of polymer crystals is far from thermodynamic equilibrium. Our results concur with various experiments. It is the first time that such growth/reorganization behavior is clearly observed by MD simulations. Our code can be easily used to model other type of polymers by providing a file containing the tabulated angle potential data and a set of appropriate parameters. Program summaryProgram title: lammps-cgpva Catalogue identifier: AEDE_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEDE_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU's GPL No. of lines in distributed program

Characterization and dynamic charge dependent modeling of conducting polymer trilayer bending

NASA Astrophysics Data System (ADS)

Farajollahi, Meisam; Sassani, Farrokh; Naserifar, Naser; Fannir, Adelyne; Plesse, Cédric; Nguyen, Giao T. M.; Vidal, Frédéric; Madden, John D. W.

2016-11-01

Trilayer bending actuators are charge driven devices that have the ability to function in air and provide large mechanical amplification. The electronic and mechanical properties of these actuators are known to be functions of their charge state making prediction of their responses more difficult when they operate over their full range of deformation. In this work, a combination of state space representation and a two-dimensional RC transmission line model are used to implement a nonlinear time variant model for conducting polymer-based trilayer actuators. Electrical conductivity and Young’s modulus of electromechanically active PEDOT conducting polymer containing films as a function of applied voltage were measured and incorporated into the model. A 16% drop in Young’s modulus and 24 times increase in conductivity are observed by oxidizing the PEDOT. A closed form formulation for radius of curvature of trilayer actuators considering asymmetric and location dependent Young’s modulus and conductivity in the conducting polymer layers is derived and implemented in the model. The nonlinear model shows the capability to predict the radius of curvature as a function of time and position with reasonable consistency (within 4%). The formulation is useful for general trilayer configurations to calculate the radius of curvature as a function of time. The proposed electrochemical modeling approach may also be useful for modeling energy storage devices.

Interactive effects of naphthalene treatment and the onset of vitellogenesis on energy metabolism in liver and gonad, and plasma steroid hormones of rainbow trout Oncorhynchus mykiss.

PubMed

Tintos, Adrián; Gesto, Manuel; Alvarez, Rosa; Míguez, Jesús M; Soengas, José L

2006-10-01

The purpose of the study was to assess in female fish the possible interaction between treatment with a polycyclic aromatic hydrocarbon (PAH) like naphthalene and the onset of vitellogenesis. In a first experiment, female rainbow trout (Oncorhynchus mykiss) at stages 2-3 (previtellogenesis) or 4 (early vitellogenesis) were intraperitoneally injected (2 microl g(-1)) with vegetable oil alone (control) or containing naphthalene (50 mg kg(-1)) to be sampled 3 h later. A second experiment was similarly designed but using fish intraperitoneally implanted (10 microl g(-1)) with slow-release coconut oil implants alone (control) or containing 50 mg naphthalene kg(-1) body mass that were sampled 3 days after injection. On each sampling time, plasma levels of cortisol and 17beta-estradiol, and several metabolic parameters in plasma, liver and gonad were assessed. In controls, early vitellogenic fish compared with previtellogenic fish displayed changes that in some cases are confirmatory of previous studies whereas in other cases provide new information in plasma (increased amino acid levels), liver (decreased capacity for exporting glucose and reduced amino acid levels) and gonad (decreased amino acid levels). Naphthalene treatment produced in previtellogenic fish decreased 17beta-estradiol levels in plasma, increased plasma glucose or decreased liver gluconeogenic capacity whereas no major effects were noticed on parameters involved in lipid, amino acid and lactate metabolism. Differential effects of naphthalene treatment were noticed in early vitellogenic fish such as decreased 17beta-estradiol and glucose levels in plasma, increased hexokinase and glucokinase and lack of changes in fructose 1,6-bisphosphatase activities in liver, and a lower decrease of amino acid levels in gonad. Those alterations produced by naphthalene treatment resulted in a decreased capacity for covering the energy demand of vitellogenesis in liver and gonad that could contribute to a delay and

Modeling and control of a self-sensing polymer metal composite actuator

NASA Astrophysics Data System (ADS)

Nam, Doan Ngoc Chi; Ahn, Kyoung Kwan

2014-02-01

An ion polymer metal composite (IPMC) is an electro-active polymer (EAP) that bends in response to a small applied electrical field as a result of mobility of cations in the polymer network and vice versa. One drawback in the use of an IPMC is the sensing problem for such a small size actuator. The aim of this paper is to develop a physical model for a self-sensing IPMC actuator and to verify its applicability for practical position control. Firstly, ion dynamics inside a polymer membrane is investigated with an asymmetric solution in the presence of distributed surface resistance. Based on this analysis, a modified equivalent circuit and a simple configuration to realize the self-sensing IPMC actuator are proposed. Mathematical modelling and experimental evaluation indicate that the bending curvature can be obtained accurately using several feedback voltage signals along with the IPMC length. Finally, the controllability of the developed self-sensing IPMC actuator is investigated using a robust position control. Experimental results prove that the self-sensing characteristics can be applied in engineering control problems to provide a more convenient sensing method for IPMC actuating systems.

Dependence of physical and mechanical properties on polymer architecture for model polymer networks

NASA Astrophysics Data System (ADS)

Guo, Ruilan

Effect of architecture at nanoscale on the macroscopic properties of polymer materials has long been a field of major interest, as evidenced by inhomogeneities in networks, multimodal network topologies, etc. The primary purpose of this research is to establish the architecture-property relationship of polymer networks by studying the physical and mechanical responses of a series of topologically different PTHF networks. Monodispersed allyl-tenninated PTHF precursors were synthesized through "living" cationic polymerization and functional end-capping. Model networks of various crosslink densities and inhomogeneities levels (unimodal, bimodal and clustered) were prepared by endlinking precursors via thiol-ene reaction. Thermal characteristics, i.e., glass transition, melting point, and heat of fusion, of model PTHF networks were investigated as functions of crosslink density and inhomogeneities, which showed different dependence on these two architectural parameters. Study of freezing point depression (FPD) of solvent confined in swollen networks indicated that the size of solvent microcrystals is comparable to the mesh size formed by intercrosslink chains depending on crosslink density and inhomogeneities. Relationship between crystal size and FPD provided a good reflection of the existing architecture facts in the networks. Mechanical responses of elastic chains to uniaxial strains were studied through SANS. Spatial inhomogeneities in bimodal and clustered networks gave rise to "abnormal butterfly patterns", which became more pronounced as elongation ratio increases. Radii of gyration of chains were analyzed at directions parallel and perpendicular to stretching axis. Dependence of Rg on lambda was compared to three rubber elasticity models and the molecular deformation mechanisms for unimodal, bimodal and clustered networks were explored. The thesis focused its last part on the investigation of evolution of free volume distribution of linear polymer (PE

Structure and Dynamics of Polymer/Polymer grafted nanoparticle composite

NASA Astrophysics Data System (ADS)

Archer, Lynden

Addition of nanoparticles to polymers is a well-practiced methodology for augmenting various properties of the polymer host, including mechanical strength, thermal stability, barrier properties, dimensional stability and wear resistance. Many of these property changes are known to arise from nanoparticle-induced modification of polymer structure and chain dynamics, which are strong functions of the dispersion state of the nanoparticles' and on their relative size (D) to polymer chain dimensions (e.g. Random coil radius Rg or entanglement mesh size a) . This talk will discuss polymer nanocomposites (PNCs) comprised of Polyethylene Glycol (PEG) tethered silica nanoparticles (SiO2-PEG) dispersed in polymers as model systems for investigating phase stability and dynamics of PNCs. On the basis of small-angle X-ray Scattering, it will be shown that favorable enthalpic interactions between particle-tethered chains and a polymer host provides an important mechanism for creating PNCs in which particle aggregation is avoided. The talk will report on polymer and particle scale dynamics in these materials and will show that grafted nanoparticles well dispersed in a polymer host strongly influence the host polymer relaxation dynamics on all timescales and the polymers in turn produce dramatic changes in the nature (from diffusive to hyperdiffusive) and speed of nano particle decorrelation dynamics at the polymer entanglement threshold. A local viscosity model capable of explaining these observations is discussed and the results compared with scaling theories for NP motions in polymers This material is based on work supported by the National Science Foundation Award Nos. DMR-1609125 and CBET-1512297.

An atomic finite element model for biodegradable polymers. Part 2. A model for change in Young's modulus due to polymer chain scission.

PubMed

Gleadall, Andrew; Pan, Jingzhe; Kruft, Marc-Anton

2015-11-01

Atomic simulations were undertaken to analyse the effect of polymer chain scission on amorphous poly(lactide) during degradation. Many experimental studies have analysed mechanical properties degradation but relatively few computation studies have been conducted. Such studies are valuable for supporting the design of bioresorbable medical devices. Hence in this paper, an Effective Cavity Theory for the degradation of Young's modulus was developed. Atomic simulations indicated that a volume of reduced-stiffness polymer may exist around chain scissions. In the Effective Cavity Theory, each chain scission is considered to instantiate an effective cavity. Finite Element Analysis simulations were conducted to model the effect of the cavities on Young's modulus. Since polymer crystallinity affects mechanical properties, the effect of increases in crystallinity during degradation on Young's modulus is also considered. To demonstrate the ability of the Effective Cavity Theory, it was fitted to several sets of experimental data for Young's modulus in the literature. Copyright © 2015 Elsevier Ltd. All rights reserved.

Modelling of polymer photodegradation for solar cell modules

NASA Technical Reports Server (NTRS)

Somersall, A. C.; Guillet, J. E.

1981-01-01

A computer program developed to model and calculate by numerical integration the varying concentrations of chemical species formed during photooxidation of a polymeric material over time, using as input data a choice set of elementary reactions, corresponding rate constants and a convenient set of starting conditions is evaluated. Attempts were made to validate the proposed mechanism by experimentally monitoring the photooxidation products of small liquid alkane which are useful starting models for ethylene segments of polymers like EVA. The model system proved in appropriate for the intended purposes. Another validation model is recommended.

Swelling equilibrium of dentin adhesive polymers formed on the water-adhesive phase boundary: Experiments and micromechanical model

PubMed Central

Misra, Anil; Parthasarathy, Ranganathan; Ye, Qiang; Singh, Viraj; Spencer, Paulette

2013-01-01

During their application to the wet, oral environment, dentin adhesives can experience phase separation and composition change which can compromise the quality of the hybrid layer formed at the dentin-adhesive interface. The chemical composition of polymer phases formed in the hybrid layer can be represented using a ternary water-adhesive phase diagram. In this paper, these polymer phases have been characterized using a suite of mechanical tests and swelling experiments. The experimental results were evaluated using granular micromechanics based model that incorporates poro-mechanical effects and polymer-solvent thermodynamics. The variation of the model parameters and model-predicted polymer properties has been studied as a function of composition along the phase boundary. The resulting structure-property correlations provide insight into interactions occurring at the molecular level in the saturated polymer system. These correlations can be used for modeling the mechanical behavior of hybrid layer, and are expected to aid in the design and improvement of water-compatible dentin adhesive polymers. PMID:24076070

Formulation of 3D Printed Tablet for Rapid Drug Release by Fused Deposition Modeling: Screening Polymers for Drug Release, Drug-Polymer Miscibility and Printability.

PubMed

Solanki, Nayan G; Tahsin, Md; Shah, Ankita V; Serajuddin, Abu T M

2018-01-01

The primary aim of this study was to identify pharmaceutically acceptable amorphous polymers for producing 3D printed tablets of a model drug, haloperidol, for rapid release by fused deposition modeling. Filaments for 3D printing were prepared by hot melt extrusion at 150°C with 10% and 20% w/w of haloperidol using Kollidon ® VA64, Kollicoat ® IR, Affinsiol ™ 15 cP, and HPMCAS either individually or as binary blends (Kollidon ® VA64 + Affinisol ™ 15 cP, 1:1; Kollidon ® VA64 + HPMCAS, 1:1). Dissolution of crushed extrudates was studied at pH 2 and 6.8, and formulations demonstrating rapid dissolution rates were then analyzed for drug-polymer, polymer-polymer and drug-polymer-polymer miscibility by film casting. Polymer-polymer (1:1) and drug-polymer-polymer (1:5:5 and 2:5:5) mixtures were found to be miscible. Tablets with 100% and 60% infill were printed using MakerBot printer at 210°C, and dissolution tests of tablets were conducted at pH 2 and 6.8. Extruded filaments of Kollidon ® VA64-Affinisol ™ 15 cP mixtures were flexible and had optimum mechanical strength for 3D printing. Tablets containing 10% drug with 60% and 100% infill showed complete drug release at pH 2 in 45 and 120 min, respectively. Relatively high dissolution rates were also observed at pH 6.8. The 1:1-mixture of Kollidon ® VA64 and Affinisol ™ 15 cP was thus identified as a suitable polymer system for 3D printing and rapid drug release. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Non-monotonic course of protein solubility in aqueous polymer-salt solutions can be modeled using the sol-mxDLVO model.

PubMed

Herhut, Marcel; Brandenbusch, Christoph; Sadowski, Gabriele

2016-02-01

Protein purification is often performed using cost-intensive chromatographic steps. To discover economic alternatives (e.g., crystallization), knowledge on protein solubility as a function of temperature, pH, and additives in solution as well as their concentration is required. State-of-the-art models for predicting protein solubility almost exclusively consider aqueous salt systems, whereas "salting-in" and "salting-out" effects induced by the presence of an additional polymer are not considered. Thus, we developed the sol-mxDLVO model. Using this newly developed model, protein solubility in the presence of one salt and one polymer, especially the non-monotonic course of protein solubility, could be predicted. Systems considered included salts (NaCl, Na-p-Ts, (NH(4))(2) SO(4)) and the polymer polyethylene glycol (MW: 2000 g/mol, 12000 g/mol) and proteins lysozyme from chicken egg white (pH 4 to 5.5) and D-xylose ketol-isomerase (pH 7) at 298.15 K. The results show that by using the sol-mxDLVO model, protein solubility in polymer-salt solutions can be modeled in good agreement with the experimental data for both proteins considered. The sol-mxDLVO model can describe the non-monotonic course of protein solubility as a function of polymer concentration and salt concentration, previously not covered by state-of-the-art models. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Emission of Polychlorinated Naphthalenes during Thermal Related Processes

NASA Astrophysics Data System (ADS)

Liu, Guorui; Zheng, Minghui; Du, Bing; Liu, Wenbin; Zhang, Bing; Xiao, Ke

2010-05-01

Due to the structural similarity of polychlorinated naphthalenes (PCNs) to those of dioxins, PCNs exhibit toxicological properties similar to dioxins (Olivero-Verbel et al., 2004). Based on their high toxicity, persistence, bioaccumulation, and long-distance transmission, PCNs were also selected as a candidate POP for the UN-ECE (United Nations Economic Commission for Europe) POP protocol (Lerche et al., 2002). In addition, some studies suggested that PCNs contributed a greater proportion of the dioxin-like activity than polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) contributed in some locations (Kannan et al., 1998). However, the identification and quantitation for PCN sources are very scarce compared with PCDD/Fs. Understanding the emission levels and developing the emission inventory of PCNs is important for regulatory and source reduction purposes. In this study, several potential sources were preliminarily investigated for PCN release. Coking process (CP), iron ore sintering (IOS), and electric arc furnace steel making units (AF) were selected due to their huge activity level of industrial production in China. Municipal solid waste incineration (MSWI) and medical waste incineration (MWI) were also investigated because of the possible high concentration of PCNs in stack gas. Two plants were investigated for each thermal related process, except for MWI with one incinerator was investigated. The stack gas samples were collected by automatic isokinetic sampling system (Isostack Basic, TCR TECORA, Milan Italy). Isotope dilution high resolution gas chromatography coupled with high resolution mass spectrometry (HRGC/HRMS) technique was used for the identification and quantitation of PCN congeners. The concentrations of PCNs from the selected thermal processes were determined in this study. The average concentrations of total PCNs were 26 ng Nm-3 for CP, 65 ng Nm-3 for IOS, 720 ng Nm-3 for AF, 443 ng Nm-3 for MSWI, and

1-anilino-8-naphthalene sulfonate as a protein conformational tightening agent.

PubMed

Matulis, D; Baumann, C G; Bloomfield, V A; Lovrien, R E

1999-05-01

1-Anilino-8-naphthalene sulfonate (ANS) anion is conventionally considered to bind to preexisting hydrophobic (nonpolar) surfaces of proteins, primarily through its nonpolar anilino-naphthalene group. Such binding is followed by an increase in ANS fluorescence intensity, similar to that occurring when ANS is dissolved in organic solvents. It is generally assumed that neither the negative sulfonate charge on the ANS, nor charges on the protein, participate significantly in ANS-protein interaction. However, titration calorimetry has demonstrated that most ANS binding to a number of proteins occurs through electrostatic forces, in which ion pairs are formed between ANS sulfonate groups and cationic groups on the proteins (D. Matulis and R. E. Lovrien, Biophys. J., 1998, Vol. 74, pp. 1-8). Here we show by viscometry and diffusion coefficient measurements that bovine serum albumin and gamma-globulin, starting from their acid-expanded, most hydrated conformations, undergo extensive molecular compaction upon ANS binding. As the cationic protein binds negatively charged ANS anion it also takes up positively charged protons from water to compensate the effect of the negative charge, and leaves the free hydroxide anions in solution thus shifting pH upward (the Scatchard-Black effect). These results indicate that ANS is not always a definitive reporter of protein molecular conformation that existed before ANS binding. Instead, ANS reports on a conformationally tightened state produced by the interplay of ionic and hydrophobic characters of both protein and ligand.

Ageing of polymer bonds: a coupled chemomechanical modelling approach

NASA Astrophysics Data System (ADS)

Dippel, Benedikt; Johlitz, Michael; Lion, Alexander

2014-05-01

With the increasing number of requirements on joinings, it gets more and more important to understand and predict an assemblies properties. Nowadays, in industrial applications, combinations of different materials get more common. In most of those cases, it is, besides other advantages, useful to connect such parts with adhesives to avoid local cells. Thus, the knowledge about the mechanical behaviour of adhesives over the whole time of utilisation is an essential element of engineering. As it is well known, ageing due to environmental influences such as oxygen, radiation, ozone and others plays a major role in polymers properties. So, for the prediction of applicability over the whole lifetime of a technical component, the change in mechanical properties due to ageing is necessary. In this contribution, we introduce a material model which takes into account the internal structure of an adhesive. Therefore, an interphase zone is introduced. In the interphase, which is developed due to the contact of an adhesive with an adherent, the materials properties change continuously from the surface to the centre of the joint, where the polymer is in a bulky state. Built up on this geometry dependency, the materials ageing as a function of the position is described. To model the change of the polymers state, we use a parameter representing chain scission processes and another one for the reformation of a new network. In a last step, the model is transferred into a finite element code for exemplary calculations.

Finite element modeling of the electromechanical coupling in ionic polymer transducers

NASA Astrophysics Data System (ADS)

Akle, Barbar; Habchi, Wassim; Wallmersperger, Thomas; Leo, Donald

2010-04-01

Several researchers are actively studying Ionomeric polymer transducers (IPT) as a large strain low voltage Electro- Active Polymer (EAP) actuator. EAPs are devices that do not contain any moving parts leading to a potential large life time. Furthermore, they are light weight and flexible. An IPT is made of an ion saturated polymer usually Nafion, sandwiched between two electrodes made of a mixture of Nafion and electrically conductive particles usually RuO2 or platinum. Nafion is an acid membrane in which the cations are mobile while the anions are covalently fixed to the polymer structure. Upon the application of an electric potential on the order of 2V at the electrodes the mobile positive ions migrate towards the cathode leading to bending strains in the order of 5%. Our earlier studies demonstrate that the cations develop thin boundary layers around the electrode. Later developments in this finite element model captured the importance of adding particles in the electrode. This study presents the electromechanical coupling in ionic polymer transducers. Since all our earlier models were restricted to the electro-chemical part, here we will introduce the chemomechanical coupling. This coupling is performed based on previous studies (Akle and Leo) in which the authors experimentally showed that the mechanical strain in IPTs is proportional to a linear term and a quadratic term of the charge accumulated at the electrode. The values of the linear and quadratic terms are extracted from experimental data.

Real time polymer nanocomposites-based physical nanosensors: theory and modeling.

PubMed

Bellucci, Stefano; Shunin, Yuri; Gopeyenko, Victor; Lobanova-Shunina, Tamara; Burlutskaya, Nataly; Zhukovskii, Yuri

2017-09-01

Functionalized carbon nanotubes and graphene nanoribbons nanostructures, serving as the basis for the creation of physical pressure and temperature nanosensors, are considered as tools for ecological monitoring and medical applications. Fragments of nanocarbon inclusions with different morphologies, presenting a disordered system, are regarded as models for nanocomposite materials based on carbon nanoсluster suspension in dielectric polymer environments (e.g., epoxy resins). We have formulated the approach of conductivity calculations for carbon-based polymer nanocomposites using the effective media cluster approach, disordered systems theory and conductivity mechanisms analysis, and obtained the calibration dependences. Providing a proper description of electric responses in nanosensoring systems, we demonstrate the implementation of advanced simulation models suitable for real time control nanosystems. We also consider the prospects and prototypes of the proposed physical nanosensor models providing the comparisons with experimental calibration dependences.

Real time polymer nanocomposites-based physical nanosensors: theory and modeling

NASA Astrophysics Data System (ADS)

Bellucci, Stefano; Shunin, Yuri; Gopeyenko, Victor; Lobanova-Shunina, Tamara; Burlutskaya, Nataly; Zhukovskii, Yuri

2017-09-01

Functionalized carbon nanotubes and graphene nanoribbons nanostructures, serving as the basis for the creation of physical pressure and temperature nanosensors, are considered as tools for ecological monitoring and medical applications. Fragments of nanocarbon inclusions with different morphologies, presenting a disordered system, are regarded as models for nanocomposite materials based on carbon nanoсluster suspension in dielectric polymer environments (e.g., epoxy resins). We have formulated the approach of conductivity calculations for carbon-based polymer nanocomposites using the effective media cluster approach, disordered systems theory and conductivity mechanisms analysis, and obtained the calibration dependences. Providing a proper description of electric responses in nanosensoring systems, we demonstrate the implementation of advanced simulation models suitable for real time control nanosystems. We also consider the prospects and prototypes of the proposed physical nanosensor models providing the comparisons with experimental calibration dependences.

Modeling of mechanical properties of stack actuators based on electroactive polymers

NASA Astrophysics Data System (ADS)

Tepel, Dominik; Graf, Christian; Maas, Jürgen

2013-04-01

Dielectric elastomers are thin polymer films belonging to the class of electroactive polymers, which are coated with compliant and conductive electrodes on each side. Under the influence of an electrical field, dielectric elastomers perform a large amount of deformation. Depending on the mechanical setup, stack and roll actuators can be realized. In this contribution the mechanical properties of stack actuators are modeled by a holistic electromechanical approach of a single actuator film, by which the model of a stack actuator without constraints can be derived. Due to the mechanical connection between the stack actuator and the application, bulges occur at the free surfaces of the EAP material, which are calculated, experimentally validated and considered in the model of the stack actuator. Finally, the analytic actuator film model as well as the stack actuator model are validated by comparison to numerical FEM-models in ANSYS.

What Is the Structure of the Naphthalene-Benzene Heterodimer Radical Cation? Binding Energy, Charge Delocalization, and Unexpected Charge-Transfer Interaction in Stacked Dimer and Trimer Radical Cations.

PubMed

Attah, Isaac K; Platt, Sean P; Meot-Ner Mautner, Michael; El-Shall, M Samy; Peverati, Roberto; Head-Gordon, Martin

2015-04-02

The binding energy of the naphthalene(+•)(benzene) heterodimer cation has been determined to be 7.9 ± 1 kcal/mol for C10H8(+•)(C6H6) and 8.1 ± 1 kcal/mol for C10H8(+•)(C6D6) by equilibrium thermochemical measurements using the mass-selected drift cell technique. A second benzene molecule binds to the C10H8(+•)(C6D6) dimer with essentially the same energy (8.4 ± 1 kcal/mol), suggesting that the two benzene molecules are stacked on opposite sides of the naphthalene cation in the (C6D6)C10H8(+•)(C6D6) heterotrimer. The lowest-energy isomers of the C10H8(+•)(C6D6) and (C6D6)C10H8(+•)(C6D6) dimer and trimer calculated using the M11/cc-pVTZ method have parallel stacked structures with enthalpies of binding (-ΔH°) of 8.4 and 9.0 kcal/mol, respectively, in excellent agreement with the experimental values. The stacked face-to-face class of isomers is calculated to have substantial charge-transfer stabilization of about 45% of the total interaction energy despite the large difference between the ionization energies of benzene and naphthalene. Similarly, significant delocalization of the positive charge is found among all three fragments of the (C6D6)C10H8(+•)(C6D6) heterotrimer, thus leaving only 46% of the total charge on the central naphthalene moiety. This unexpectedly high charge-transfer component results in activating two benzene molecules in the naphthalene(+•)(benzene)2 heterotrimer cation to associate with a third benzene molecule at 219 K to form a benzene trimer cation and a neutral naphthalene molecule. The global minimum of the C10H8(+•)(C6H6)2 heterotrimer is found to be the one where the naphthalene cation is sandwiched between two benzene molecules. It is remarkable, and rather unusual, that the binding energy of the second benzene molecule is essentially the same as that of the first. This is attributed to the enhanced charge-transfer interaction in the stacked trimer radical cation.

Nonlinearity and Strain-Rate Dependence in the Deformation Response of Polymer Matrix Composites Modeled

NASA Technical Reports Server (NTRS)

Goldberg, Robert K.

2000-01-01

There has been no accurate procedure for modeling the high-speed impact of composite materials, but such an analytical capability will be required in designing reliable lightweight engine-containment systems. The majority of the models in use assume a linear elastic material response that does not vary with strain rate. However, for containment systems, polymer matrix composites incorporating ductile polymers are likely to be used. For such a material, the deformation response is likely to be nonlinear and to vary with strain rate. An analytical model has been developed at the NASA Glenn Research Center at Lewis Field that incorporates both of these features. A set of constitutive equations that was originally developed to analyze the viscoplastic deformation of metals (Ramaswamy-Stouffer equations) was modified to simulate the nonlinear, rate-dependent deformation of polymers. Specifically, the effects of hydrostatic stresses on the inelastic response, which can be significant in polymers, were accounted for by a modification of the definition of the effective stress. The constitutive equations were then incorporated into a composite micromechanics model based on the mechanics of materials theory. This theory predicts the deformation response of a composite material from the properties and behavior of the individual constituents. In this manner, the nonlinear, rate-dependent deformation response of a polymer matrix composite can be predicted.

A molecular model for cohesive slip at polymer melt/solid interfaces.

PubMed

Tchesnokov, M A; Molenaar, J; Slot, J J M; Stepanyan, R

2005-06-01

A molecular model is proposed which predicts wall slip by disentanglement of polymer chains adsorbed on a wall from those in the polymer bulk. The dynamics of the near-wall boundary layer is found to be governed by a nonlinear equation of motion, which accounts for such mechanisms on surface chains as convection, retraction, constraint release, and thermal fluctuations. This equation is valid over a wide range of grafting regimes, including those in which interactions between neighboring adsorbed molecules become essential. It is not closed since the dynamics of adsorbed chains is shown to be coupled to that of polymer chains in the bulk via constraint release. The constitutive equations for the layer and bulk, together with continuity of stress and velocity, are found to form a closed system of equations which governs the dynamics of the whole "bulk+boundary layer" ensemble. Its solution provides a stick-slip law in terms of the molecular parameters and extruder geometry. The model is quantitative and contains only those parameters that can be measured directly, or extracted from independent rheological measurements. The model predictions show a good agreement with available experimental data.

Quantitative Modeling of Entangled Polymer Rheology: Experiments, Tube Models and Slip-Link Simulations

NASA Astrophysics Data System (ADS)

Desai, Priyanka Subhash

Rheology properties are sensitive indicators of molecular structure and dynamics. The relationship between rheology and polymer dynamics is captured in the constitutive model, which, if accurate and robust, would greatly aid molecular design and polymer processing. This dissertation is thus focused on building accurate and quantitative constitutive models that can help predict linear and non-linear viscoelasticity. In this work, we have used a multi-pronged approach based on the tube theory, coarse-grained slip-link simulations, and advanced polymeric synthetic and characterization techniques, to confront some of the outstanding problems in entangled polymer rheology. First, we modified simple tube based constitutive equations in extensional rheology and developed functional forms to test the effect of Kuhn segment alignment on a) tube diameter enlargement and b) monomeric friction reduction between subchains. We, then, used these functional forms to model extensional viscosity data for polystyrene (PS) melts and solutions. We demonstrated that the idea of reduction in segmental friction due to Kuhn alignment is successful in explaining the qualitative difference between melts and solutions in extension as revealed by recent experiments on PS. Second, we compiled literature data and used it to develop a universal tube model parameter set and prescribed their values and uncertainties for 1,4-PBd by comparing linear viscoelastic G' and G" mastercurves for 1,4-PBds of various branching architectures. The high frequency transition region of the mastercurves superposed very well for all the 1,4-PBds irrespective of their molecular weight and architecture, indicating universality in high frequency behavior. Therefore, all three parameters of the tube model were extracted from this high frequency transition region alone. Third, we compared predictions of two versions of the tube model, Hierarchical model and BoB model against linear viscoelastic data of blends of 1,4-PBd

Modeling the enhancement of the swimming speed of flagellated bacteria in polymer solutions

NASA Astrophysics Data System (ADS)

Tang, Jay X.; Zhang, Xuejun; Ye, Fangfu; Klimpert, William; Pelcovits, Robert

The swimming speed of many species of flagellated bacteria initially increases and then decreases as a function of the viscosity of the medium, which is varied by the addition of high molecular weight polymers. An earlier model accounts for such a peaked distribution, but it was recently shown to give rise to incorrect predictions for the cell body rotation rate. The authors of the latter work suggested that low-molecular weight impurities from the added polymers account for the peaked speed-viscosity curves in some cases. We measured the swimming speed of a uni-flagellated bacterium, caulobacter crescentus, in solutions of a number of polymers of several different sizes. Our findings confirm the peaked speed-viscosity curve for each of several distinct polymers added, suggesting that the general behavior is highly unlikely due to impurities. We propose a modification of the models used by the previous investigators in order to better explain our new experimental results. We have also performed numerical calculations based on the modified model to show that it properly accounts for the experimental results. NSF CBET 1438033 and Institute of Theoretical Physics, CAS.

Comparison of retention models for polymers 1. Poly(ethylene glycol)s.

PubMed

Bashir, Mubasher A; Radke, Wolfgang

2006-10-27

The suitability of three different retention models to predict the retention times of poly(ethylene glycol)s (PEGs) in gradient and isocratic chromatography was investigated. The models investigated were the linear (LSSM) and the quadratic solvent strength model (QSSM). In addition, a model describing the retention behaviour of polymers was extended to account for gradient elution (PM). It was found that all models are suited to properly predict gradient retention volumes provided the extraction of the analyte specific parameters is performed from gradient experiments as well. The LSSM and QSSM on principle cannot describe retention behaviour under critical or SEC conditions. Since the PM is designed to cover all three modes of polymer chromatography, it is therefore superior to the other models. However, the determination of the analyte specific parameters, which are needed to calibrate the retention behaviour, strongly depend on the suitable selection of initial experiments. A useful strategy for a purposeful selection of these calibration experiments is proposed.

Accumulation of 14C-naphthalene in the tissues of redhead ducks fed oil-contaminated crayfish

USGS Publications Warehouse

Tarshis, I.B.; Rattner, B.A.

1982-01-01

Crayfish, artificially contaminated with14C-naphthalene-5% water-soluble fraction of No. 2 fuel oil, were force-fed to one-year-old redhead ducks to determine the accumulation of petroleum hydrocarbons. The relative distribution of carbon-14 activity in the gall bladder containing bile, and fat were similar, and significantly greater (P < 0.05) than the activity in the blood, brain, liver, and kidney. There was a significant increase (P < 0.05) in the disintegrations per minute per gram (dpm/g) in the blood, brain, kidney, and liver between days 1 and 3 of feeding, indicating a progressive accumulation of carbon-14 activity (naphthalene and presumably its metabolites). There was no significant effect of sex or the interaction of the duration of feeding and sex on carbon-14 activity in any of the tissues. The low daily dose of petroleum hydrocarbons (a total of approximately 1.25 mg/day) received by the ducks from the crayfish and the relatively short feeding regimen did not cause any overt signs of toxicity in the ducks.

Shell model for drag reduction with polymer additives in homogeneous turbulence.

PubMed

Benzi, Roberto; De Angelis, Elisabetta; Govindarajan, Rama; Procaccia, Itamar

2003-07-01

Recent direct numerical simulations of the finite-extensibility nonlinear elastic dumbbell model with the Peterlin approximation of non-Newtonian hydrodynamics revealed that the phenomenon of drag reduction by polymer additives exists (albeit in reduced form) also in homogeneous turbulence. We use here a simple shell model for homogeneous viscoelastic flows, which recaptures the essential observations of the full simulations. The simplicity of the shell model allows us to offer a transparent explanation of the main observations. It is shown that the mechanism for drag reduction operates mainly on large scales. Understanding the mechanism allows us to predict how the amount of drag reduction depends on the various parameters in the model. The main conclusion is that drag reduction is not a universal phenomenon; it peaks in a window of parameters such as the Reynolds number and the relaxation rate of the polymer.

Predictive Modeling of Polymer Mechanical Behavior Coupled to Chemical Change/ Technique Development for Measuring Polymer Physical Aging.

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

Kropka, Jamie Michael; Stavig, Mark E.; Arechederra, Gabe Kenneth

Develop an understanding of the evolution of glassy polymer mechanical response during aging and the mechanisms associated with that evolution. That understanding will be used to develop constitutive models to assess the impact of stress evolution in encapsulants on NW designs.

Modeling Fungal Melanin Buildup: Biomimetic Polymerization of 1,8-Dihydroxynaphthalene Mapped by Mass Spectrometry.

PubMed

Cecchini, Martina Maya; Reale, Samantha; Manini, Paola; d'Ischia, Marco; De Angelis, Francesco

2017-06-12

Due to the emerging biomedical relevance and technological potential of fungal melanins, and prompted by the virtual lack of information about their structural arrangement, an optimized synthetic protocol has been devised for a potential structural model of Ascomyces allomelanin through enzyme-catalyzed oxidative polymerization of 1,8-dihydroxynaphthalene (1,8-DHN). Electrospray ionization mass spectrometry (ESI-MS) measurements of freshly synthesized DHN-polymer recorded in the negative ion mode allowed detection of oligomers up to m/z 4000, separated by 158 Da, corresponding to the in-chain DHN-unit. The dominant peaks were assigned to singly-charged distribution, up to 23 repeating units, whereas a doubly charged polymer distribution was also detectable. Chemical derivatization, ultra-performance liquid chromatography (UPLC)-ESI MS, and MS/MS data confirmed that oxidative polymerization of 1,8-DHN proceeds through C-C coupling of the naphthalene rings. The new insights reported here into synthetic 1,8-DHN oligomers/polymers as a mimic of fungal melanins may guide novel interesting advances and applications in the field of biomimetic functional materials. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Molecular dynamics modeling the synthetic and biological polymers interactions pre-studied via docking

NASA Astrophysics Data System (ADS)

Tsvetkov, Vladimir B.; Serbin, Alexander V.

2014-06-01

In previous works we reported the design, synthesis and in vitro evaluations of synthetic anionic polymers modified by alicyclic pendant groups (hydrophobic anchors), as a novel class of inhibitors of the human immunodeficiency virus type 1 ( HIV-1) entry into human cells. Recently, these synthetic polymers interactions with key mediator of HIV-1 entry-fusion, the tri-helix core of the first heptad repeat regions [ HR1]3 of viral envelope protein gp41, were pre-studied via docking in terms of newly formulated algorithm for stepwise approximation from fragments of polymeric backbone and side-group models toward real polymeric chains. In the present article the docking results were verified under molecular dynamics ( MD) modeling. In contrast with limited capabilities of the docking, the MD allowed of using much more large models of the polymeric ligands, considering flexibility of both ligand and target simultaneously. Among the synthesized polymers the dinorbornen anchors containing alternating copolymers of maleic acid were selected as the most representative ligands (possessing the top anti-HIV activity in vitro in correlation with the highest binding energy in the docking). To verify the probability of binding of the polymers with the [HR1]3 in the sites defined via docking, various starting positions of polymer chains were tried. The MD simulations confirmed the main docking-predicted priority for binding sites, and possibilities for axial and belting modes of the ligands-target interactions. Some newly MD-discovered aspects of the ligand's backbone and anchor units dynamic cooperation in binding the viral target clarify mechanisms of the synthetic polymers anti-HIV activity and drug resistance prevention.

Numerical model of the polymer electro-optic waveguide

NASA Astrophysics Data System (ADS)

Fan, Guofang; Li, Yuan; Han, Bing; Wang, Qi; Liu, Xinhou; Zhen, Zhen

2012-09-01

A numerical design model is presented for the polymer waveguide in an electro-optic modulator. The effective index method is used to analyze the height of the core waveguide and rib waveguide, an improved Marcatili method is presented to design the rib waveguide width in order to keep the strong single mode operation and have a good match with the standard fiber. Also, the thickness of the upper cladding layer is discussed through calculating the effective index of the multilayer planar waveguide structure has been obtained by setting the optical loss due to the metallic absorption to an acceptable value (<0.1 dB/cm). As a consequence, we take the EO polymer waveguide structure of UV15:CLD/APC:UFC170 as an example, an optimized design is reported.

Final Report from the External Peer Review of the IRIS Reassessment of the Inhalation Carcinogenicity of Naphthalene

EPA Science Inventory

This document is the final report for the 2004 external peer review for the EPA IRIS Reassessment of the Inhalation Carcinogenicity of Naphthalene, prepared by the Office of Research and Development's National Center for Environmental Assessment (NCEA), for the Integrated ...

Mechanical and kinetic study on gas-phase formation of dinitro-naphthalene from 1- and 2-nitronaphthalene.

PubMed

Huang, Zixiao; Zhang, Qingzhu; Wang, Wenxing

2016-08-01

Nitrated polycyclic aromatic hydrocarbons have received an increasing number of considerations because of their higher mutagens than parent PAHs. In this paper, the formation of dinitro-naphthalene was investigated mechanistically using 1- and 2-nitronaphthalene as precursors with the aid of high-accuracy quantum chemistry calculation. The geometrical parameters, as well as vibrational frequencies, were calculated at the BB1K/6-31+G(d,p) level. Water molecule plays an important role in the formation of dinitro-naphthalene. The rate constants were deduced by canonical variational transition-state theory with small curvature tunneling contribution over the temperature range of 273-333 K. Meanwhile, the Arrhenius formulas were fitted for the OH addition of both 1- and 2-nitronaphthalene. The calculated overall rate constants for 1-nitronaphthalene and 2-nitronaphthalene at 298 K and 1 atm are 7.43 × 10(-13) and 7.48 × 10(-13) cm(3) molecule(-1) s(-1), respectively. The rate constants of NO3 addition to 1-nitronaphthalene and 2-nitronaphthalene by RRKM method at 298 K and 1 atm are 3.55 × 10(-15) and 3.47 × 10(-15) cm(3) molecule(-1) s(-1), respectively. This study provides a comprehensive investigation of the formation process of dinitro-naphthalenes, initiated by OH and NO3 radicals and should facilitate to illuminate its atmospheric source. Oxygen may probably be competitive with the second NO2 addition step when the concentration of NO2 is at low level. Copyright © 2016. Published by Elsevier Ltd.

Chemical and Temperature Effects on Diffusion in a Model Polymer/Nanoparticle Composite

NASA Astrophysics Data System (ADS)

Janes, Dustin; Durning, Christopher

Polymers and inks used in medical devices may be strengthened with nanoparticle fillers, so an understanding of how they may affect the release of residuals and additives via diffusion will help modernize biocompatibility testing. Transport of small molecules in polymers with increasing volume fraction of impermeable nanoparticles is often poorly predicted by the simple Maxwell model for heterogeneous media. In this presentation we will examine two diffusant classes, only one of which possesses hydrogen bonding interactions with the nanoparticle surface. Since similar reductions in mutual diffusion coefficients were observed in both cases we attribute the enhancement of the ''blocking effect'' in nanocomposites to a reduction in polymer mobility in the interfacial volume near the nanoparticle. The temperature and penetrant concentration dependence of the diffusion coefficients were examined in the context of a Vrentas-Duda free volume model that includes a thermally activated prefactor. While data obtained for rubbery poly(methyl acrylate) clearly obeys the expected Arrhenius scaling with EA = 11 kJ/mol, results for films containing d = 14 nm spherical silica nanoparticles do not, providing more evidence that polymer free volume is perturbed in unexpected ways even for conceptually simple systems. National Science Foundation IGERT Program, Pall Corporation.

Piezoelectric Polymers

NASA Technical Reports Server (NTRS)

Harrison, J. S.; Ounaies, Z.; Bushnell, Dennis M. (Technical Monitor)

2001-01-01

The purpose of this review is to detail the current theoretical understanding of the origin of piezoelectric and ferroelectric phenomena in polymers; to present the state-of-the-art in piezoelectric polymers and emerging material systems that exhibit promising properties; and to discuss key characterization methods, fundamental modeling approaches, and applications of piezoelectric polymers. Piezoelectric polymers have been known to exist for more than forty years, but in recent years they have gained notoriety as a valuable class of smart materials.

Fast Three-Dimensional Method of Modeling Atomic Oxygen Undercutting of Protected Polymers

NASA Technical Reports Server (NTRS)

Snyder, Aaron; Banks, Bruce A.

2002-01-01

A method is presented to model atomic oxygen erosion of protected polymers in low Earth orbit (LEO). Undercutting of protected polymers by atomic oxygen occurs in LEO due to the presence of scratch, crack or pin-window defects in the protective coatings. As a means of providing a better understanding of undercutting processes, a fast method of modeling atomic-oxygen undercutting of protected polymers has been developed. Current simulation methods often rely on computationally expensive ray-tracing procedures to track the surface-to-surface movement of individual "atoms." The method introduced in this paper replaces slow individual particle approaches by substituting a model that utilizes both a geometric configuration-factor technique, which governs the diffuse transport of atoms between surfaces, and an efficient telescoping series algorithm, which rapidly integrates the cumulative effects stemming from the numerous atomic oxygen events occurring at the surfaces of an undercut cavity. This new method facilitates the systematic study of three-dimensional undercutting by allowing rapid simulations to be made over a wide range of erosion parameters.

Chemically Realistic Tetrahedral Lattice Models for Polymer Chains: Application to Polyethylene Oxide.

PubMed

Dietschreit, Johannes C B; Diestler, Dennis J; Knapp, Ernst W

2016-05-10

To speed up the generation of an ensemble of poly(ethylene oxide) (PEO) polymer chains in solution, a tetrahedral lattice model possessing the appropriate bond angles is used. The distance between noncovalently bonded atoms is maintained at realistic values by generating chains with an enhanced degree of self-avoidance by a very efficient Monte Carlo (MC) algorithm. Potential energy parameters characterizing this lattice model are adjusted so as to mimic realistic PEO polymer chains in water simulated by molecular dynamics (MD), which serves as a benchmark. The MD data show that PEO chains have a fractal dimension of about two, in contrast to self-avoiding walk lattice models, which exhibit the fractal dimension of 1.7. The potential energy accounts for a mild hydrophobic effect (HYEF) of PEO and for a proper setting of the distribution between trans and gauche conformers. The potential energy parameters are determined by matching the Flory radius, the radius of gyration, and the fraction of trans torsion angles in the chain. A gratifying result is the excellent agreement of the pair distribution function and the angular correlation for the lattice model with the benchmark distribution. The lattice model allows for the precise computation of the torsional entropy of the chain. The generation of polymer conformations of the adjusted lattice model is at least 2 orders of magnitude more efficient than MD simulations of the PEO chain in explicit water. This method of generating chain conformations on a tetrahedral lattice can also be applied to other types of polymers with appropriate adjustment of the potential energy function. The efficient MC algorithm for generating chain conformations on a tetrahedral lattice is available for download at https://github.com/Roulattice/Roulattice .

Chemical and cellular oxidant production induced by naphthalene secondary organic aerosol (SOA): effect of redox-active metals and photochemical aging.

PubMed

Tuet, Wing Y; Chen, Yunle; Fok, Shierly; Gao, Dong; Weber, Rodney J; Champion, Julie A; Ng, Nga L

2017-11-09

Exposure to air pollution is a leading global health risk. Secondary organic aerosol (SOA) constitute a large portion of ambient particulate matter (PM). In this study, the water-soluble oxidative potential (OP) determined by dithiothreitol (DTT) consumption and intracellular reactive oxygen and nitrogen species (ROS/RNS) production was measured for SOA generated from the photooxidation of naphthalene in the presence of iron sulfate and ammonium sulfate seed particles. The measured intrinsic OP varied for aerosol formed using different initial naphthalene concentrations, however, no trends were observed between OP and bulk aerosol composition or seed type. For all experiments, aerosol generated in the presence of iron-containing seed induced higher ROS/RNS production compared to that formed in the presence of inorganic seed. This effect was primarily attributed to differences in aerosol carbon oxidation state [Formula: see text]. In the presence of iron, radical concentrations are elevated via iron redox cycling, resulting in more oxidized species. An exponential trend was also observed between ROS/RNS and [Formula: see text] for all naphthalene SOA, regardless of seed type or aerosol formation condition. This may have important implications as aerosol have an atmospheric lifetime of a week, over which [Formula: see text] increases due to continued photochemical aging, potentially resulting in more toxic aerosol.

Static, rheological and mechanical properties of polymer nanocomposites studied by computer modeling and simulation.

PubMed

Liu, Jun; Zhang, Liqun; Cao, Dapeng; Wang, Wenchuan

2009-12-28

Polymer nanocomposites (PNCs) often exhibit excellent mechanical, thermal, electrical and optical properties, because they combine the performances of both polymers and inorganic or organic nanoparticles. Recently, computer modeling and simulation are playing an important role in exploring the reinforcement mechanism of the PNCs and even the design of functional PNCs. This report provides an overview of the progress made in past decades in the investigation of the static, rheological and mechanical properties of polymer nanocomposites studied by computer modeling and simulation. Emphases are placed on exploring the mechanisms at the molecular level for the dispersion of nanoparticles in nanocomposites, the effects of nanoparticles on chain conformation and glass transition temperature (T(g)), as well as viscoelastic and mechanical properties. Finally, some future challenges and opportunities in computer modeling and simulation of PNCs are addressed.

Parametric modeling of wideband piezoelectric polymer sensors: Design for optoacoustic applications

NASA Astrophysics Data System (ADS)

Fernández Vidal, A.; Ciocci Brazzano, L.; Matteo, C. L.; Sorichetti, P. A.; González, M. G.

2017-09-01

In this work, we present a three-dimensional model for the design of wideband piezoelectric polymer sensors which includes the geometry and the properties of the transducer materials. The model uses FFT and numerical integration techniques in an explicit, semi-analytical approach. To validate the model, we made electrical and mechanical measurements on homemade sensors for optoacoustic applications. Each device was implemented using a polyvinylidene fluoride thin film piezoelectric polymer with a thickness of 25 μm. The sensors had detection areas in the range between 0.5 mm2 and 35 mm2 and were excited by acoustic pressure pulses of 5 ns (FWHM) from a source with a diameter around 10 μm. The experimental data obtained from the measurements agree well with the model results. We discuss the relative importance of the sensor design parameters for optoacoustic applications and we provide guidelines for the optimization of devices.

Phenomenological modelling of self-healing polymers based on integrated healing agents

NASA Astrophysics Data System (ADS)

Mergheim, Julia; Steinmann, Paul

2013-09-01

The present contribution introduces a phenomenological model for self-healing polymers. Self-healing polymers are a promising class of materials which mimic nature by their capability to autonomously heal micro-cracks. This self-healing is accomplished by the integration of microcapsules containing a healing agent and a dispersed catalyst into the matrix material. Propagating microcracks may then break the capsules which releases the healing agent into the microcracks where it polymerizes with the catalyst, closes the crack and 'heals' the material. The present modelling approach treats these processes at the macroscopic scale, the microscopic details of crack propagation and healing are thus described by means of continuous damage and healing variables. The formulation of the healing model accounts for the fact that healing is directly associated with the curing process of healing agent and catalyst. The model is implemented and its capabilities are studied by means of numerical examples.

Parametric modeling of wideband piezoelectric polymer sensors: Design for optoacoustic applications.

PubMed

Fernández Vidal, A; Ciocci Brazzano, L; Matteo, C L; Sorichetti, P A; González, M G

2017-09-01

In this work, we present a three-dimensional model for the design of wideband piezoelectric polymer sensors which includes the geometry and the properties of the transducer materials. The model uses FFT and numerical integration techniques in an explicit, semi-analytical approach. To validate the model, we made electrical and mechanical measurements on homemade sensors for optoacoustic applications. Each device was implemented using a polyvinylidene fluoride thin film piezoelectric polymer with a thickness of 25 μm. The sensors had detection areas in the range between 0.5 mm 2 and 35 mm 2 and were excited by acoustic pressure pulses of 5 ns (FWHM) from a source with a diameter around 10 μm. The experimental data obtained from the measurements agree well with the model results. We discuss the relative importance of the sensor design parameters for optoacoustic applications and we provide guidelines for the optimization of devices.

Urinary naphthalene and phenanthrene as biomarkers of occupational exposure to polycyclic aromatic hydrocarbons

PubMed Central

Sobus, Jon R.; Waidyanatha, Suramya; McClean, Michael D.; Herrick, Robert F.; Smith, Thomas J.; Garshick, Eric; Laden, Francine; Hart, Jaime E.; Zheng, Yuxin; Rappaport, Stephen M.

2009-01-01

Objectives We investigated the utility of unmetabolized naphthalene (Nap) and phenanthrene (Phe) in urine as surrogates for exposures to mixtures of polycyclic aromatic hydrocarbons (PAHs). Methods Our study included workers exposed to diesel exhausts (low PAH exposure level, n = 39) as well as those exposed to emissions from asphalt (medium PAH exposure level, n = 26) and coke ovens (high PAH exposure level, n = 28). Levels of Nap and Phe were measured in urine from each subject using head space-solid phase microextraction and gas chromatography-mass spectrometry. Published levels of airborne Nap, Phe, and other PAHs in the coke-producing and aluminum industries were also investigated. Results In post-shift urine, the highest estimated geometric mean concentrations of Nap and Phe were observed in coke-oven workers (Nap: 2,490 ng/l; Phe: 975 ng/l), followed by asphalt workers (Nap: 71.5 ng/l; Phe: 54.3 ng/l), and by diesel-exposed workers (Nap: 17.7 ng/l; Phe: 3.60 ng/l). After subtracting logged background levels of Nap and Phe from the logged post-shift levels of these PAHs in urine, the resulting values [referred to as ln(adjNap) and ln(adjPhe), respectively] were significantly correlated in each group of workers (0.71 ≤ Pearson r ≤ 0.89), suggesting a common exposure source in each case. Surprisingly, multiple linear regression analysis of ln(adjNap) on ln(adjPhe) showed no significant effect of the source of exposure (coke ovens, asphalt, and diesel exhaust) and further suggested that the ratio of urinary Nap/Phe (in natural scale) decreased with increasing exposure levels. These results were corroborated with published data for airborne Nap and Phe in the coke-producing and aluminum industries. The published air measurements also indicated that Nap and Phe levels were proportional to the levels of all combined PAHs in those industries. Conclusion Levels of Nap and Phe in urine reflect airborne exposures to these compounds and are promising surrogates for

Multisubstrate biodegradation kinetics of naphthalene, phenanthrene, and pyrene mixtures

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

Guha, S.; Peters, C.A.; Jaffe, P.R.

Biodegradation kinetics of naphthalene, phenanthrene and pyrene were studied in sole-substrate systems, and in binary and ternary mixtures to examine substrate interactions. The experiments were conducted in aerobic batch aqueous systems inoculated with a mixed culture that had been isolated from soils contaminated with polycyclic aromatic hydrocarbons (PAHs). Monod kinetic parameters and yield coefficients for the individual parameters and yield coefficients for the individual compounds were estimated from substrate depletion and CO{sub 2} evolution rate data in sole-substrate experiments. In all three binary mixture experiments, biodegradation kinetics were comparable to the sole-substrate kinetics. In the ternary mixture, biodegradation of naphthalenemore » was inhibited and the biodegradation rates of phenanthrene and pyrene were enhanced. A multisubstrate form of the Monod kinetic model was found to adequately predict substrate interactions in the binary and ternary mixtures using only the parameters derived from sole-substrate experiments. Numerical simulations of biomass growth kinetics explain the observed range of behaviors in PAH mixtures. In general, the biodegradation rates of the more degradable and abundant compounds are reduced due to competitive inhibition, but enhanced biodegradation of the more recalcitrant PAHs occurs due to simultaneous biomass growth on multiple substrates. In PAH-contaminated environments, substrate interactions may be very large due to additive effects from the large number of compounds present.« less

Investigating the 3.3 micron infrared fluorescence from naphthalene following ultraviolet excitation

NASA Technical Reports Server (NTRS)

Williams, Richard M.; Leone, Stephen R.

1994-01-01

Polycyclic aromatic hydrocarbon (PAH) type molecules are proposed as the carriers of the unidentified infrared (UIR) bands. Detailed studies of the 3.3 micrometer infrared emission features from naphthalene, the simplest PAH, following ultraviolet laser excitation are used in the interpretation of the 3.29 micrometer (3040 cm(sup -1)) UIR band. A time-resolved Fourier transform spectrometer is used to record the infrared emission spectrum of gas-phase naphthalene subsequent to ultraviolet excitation facilitated by an excimer laser operated at either 193 nm or 248 nm. The emission spectra differ significantly from the absorption spectrum in the same spectral region. Following 193 nm excitation the maximum in the emission profile is red-shifted 45 cm(sup -1) relative to the absorption maximum; a 25 cm(sup -1) red-shift is observed after 248 nm excitation. The red-shifting of the emission spectrum is reduced as collisional and radiative relaxation removes energy from the highly vibrationally excited molecules. Coupling between the various vibrational modes is thought to account for the differences between absorption and emission spectra. Strong visible emission is also observed following ultraviolet excitation. Visible emission may play an important role in the rate of radiative relaxation, which according to the interstellar PAH hypothesis occurs only by the slow emission of infrared photons. Studying the visible emission properties of PAH type molecules may be useful in the interpretation of the DIB's observed in absorption.

1,4-Bis(5-(naphthalen-1-yl)thiophen-2-yl)naphthalene, a small molecule, functions as a novel anti-HIV-1 inhibitor targeting the interaction between integrase and cellular Lens epithelium-derived growth factor.

PubMed

Gu, Wan-gang; Ip, Denis Tsz-Ming; Liu, Si-jie; Chan, Joseph H; Wang, Yan; Zhang, Xuan; Zheng, Yong-tang; Wan, David Chi-Cheong

2014-04-25

Translocation of viral integrase (IN) into the nucleus is a critical precondition of integration during the life cycle of HIV, a causative agent of Acquired Immunodeficiency Syndromes (AIDS). As the first discovered cellular factor to interact with IN, Lens epithelium-derived growth factor (LEDGF/p75) plays an important role in the process of integration. Disruption of the LEDGF/p75-IN interaction has provided a great interest for anti-HIV agent discovery. In this work, we reported that one small molecular compound, 1,4-bis(5-(naphthalen-1-yl)thiophen-2-yl)naphthalene(Compound 15), potently inhibit the IN-LEDGF/p75 interaction and affect the HIV-1 IN nuclear distribution at 1 μM. The putative binding mode of Compound 15 was constructed by a molecular docking simulation to provide structural insights into the ligand-binding mechanism. Compound 15 suppressed viral replication by measuring p24 antigen production in HIV-1IIIB acute infected C8166 cells with EC50 value of 11.19 μM. Compound 15 might supply useful structural information for further anti-HIV agent discovery. Copyright © 2014. Published by Elsevier Ireland Ltd.

Preparation of Entangled Polymer Melts of Various Architecture for Coarse-Grained Models

DTIC Science & Technology

2011-09-01

Simulator ( LAMMPS ). This report presents a theory overview and a manual how to use the method. 15. SUBJECT TERMS Ammunition, coarse-grained model...polymer builder, LAMMPS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT UU 18. NUMBER OF PAGES 26 19a. NAME OF RESPONSIBLE PERSON...scale Atomic/Molecular Massively Parallel Simulator ( LAMMPS ). Gel is an in house written C program of coarse- grained polymer builder, and LAMMPS is

Mathematical modeling of chemical composition modification and etching of polymers under the atomic oxygen influence

NASA Astrophysics Data System (ADS)

Chirskaia, Natalia; Novikov, Lev; Voronina, Ekaterina

2016-07-01

Atomic oxygen (AO) of the upper atmosphere is one of the most important space factors that can cause degradation of spacecraft surface. In our previous mathematical model the Monte Carlo method and the "large particles" approximation were used for simulating processes of polymer etching under the influence of AO [1]. The interaction of enlarged AO particles with the polymer was described in terms of probabilities of reactions such as etching of polymer and specular and diffuse scattering of the AO particles on polymer. The effects of atomic oxygen on protected polymers and microfiller containing composites were simulated. The simulation results were in quite good agreement with the results of laboratory experiments on magnetoplasmadynamic accelerator of the oxygen plasma of SINP MSU [2]. In this paper we present a new model that describes the reactions of AO interactions with polymeric materials in more detail. Reactions of formation and further emission of chemical compounds such as CO, CO _{2}, H _{2}O, etc. cause the modification of the chemical composition of the polymer and change the probabilities of its consequent interaction with the AO. The simulation results are compared with the results of previous simulation and with the results of laboratory experiments. The reasons for the differences between the results of natural experiments on spacecraft, laboratory experiments and simulations are discussed. N. Chirskaya, M. Samokhina, Computer modeling of polymer structures degradation under the atomic oxygen exposure, WDS'12 Proceedings of Contributed Papers: Part III - Physics, Matfyzpress Prague, 2012, pp. 30-35. E. Voronina, L. Novikov, V. Chernik, N. Chirskaya, K. Vernigorov, G. Bondarenko, and A. Gaidar, Mathematical and experimental simulation of impact of atomic oxygen of the earth's upper atmosphere on nanostructures and polymer composites, Inorganic Materials: Applied Research, 2012, vol. 3, no. 2, pp. 95-101.

Mechanism of 1,4,5,8-naphthalene tetracarboxylic acid dianhydride hydrolysis and formation in aqueous solution.

PubMed

Barros, T C; Cuccovia, I M; Farah, J P S; Masini, J C; Chaimovich, H; Politi, M J

2006-01-07

The study of highly conjugated, carbonyl-containing molecules such as 1,4,5,8-naphthalene tetracarboxylic dianhydride, III, is of interest since reactivity differences and transmission of electronic effects through the conjugated framework can be evidenced. The kinetics of hydrolysis of III in aqueous solution were determined from 5 M acid to pH 10. In basic solution hydrolysis of III yields, sequentially, 1,4,5,8-naphthalene diacid monoanhydride, II, and 1,4,5,8-naphthalene tetracarboxylic acid, I. The second order rate constant for alkaline hydrolysis is 200 fold higher for the first ring opening. The water-catalyzed hydrolysis of III yields a pH-dependent mixture of ionic forms of I and II. The rate constant for water-catalyzed hydrolysis of III is 25 fold higher than that for II. In concentrated acid the rates for reaching equilibrium (I, II and III) increase and III is the major product. The pK(a)s of I (3.24, 5.13 and 6.25) and II (3.05, 5.90) were determined by potentiometric, fluorescence and UV spectroscopy titrations and by quantitative fit of the kinetic and equilibrium data. The apparent, pH-dependent, equilibrium constants, K(EqII), for anhydride formation between I and II were obtained from the UV spectra. The quantitative fit of kinetic and equilibrium data are consistent with the assumption that anhydride formation only proceeds with the fully protonated species for both I and II and permitted the estimation of the equilibrium constants for anhydride formation, K(EqII). The value of K(EqII) (I <==> II) between pH 1 and 6 was ca. 5. Geometry optimization calculations in the gas phase of the reactions of III in alkaline, neutral and acid conditions, at the DFT level of theory, gave electronic distributions that were qualitatively consistent with the experimental results.

Glass transition temperature of polymer nano-composites with polymer and filler interactions

NASA Astrophysics Data System (ADS)

Hagita, Katsumi; Takano, Hiroshi; Doi, Masao; Morita, Hiroshi

2012-02-01

We systematically studied versatile coarse-grained model (bead spring model) to describe filled polymer nano-composites for coarse-grained (Kremer-Grest model) molecular dynamics simulations. This model consists of long polymers, crosslink, and fillers. We used the hollow structure as the filler to describe rigid spherical fillers with small computing costs. Our filler model consists of surface particles of icosahedra fullerene structure C320 and a repulsive force from the center of the filler is applied to the surface particles in order to make a sphere and rigid. The filler's diameter is 12 times of beads of the polymers. As the first test of our model, we study temperature dependence of volumes of periodic boundary conditions under constant pressures through NPT constant Andersen algorithm. It is found that Glass transition temperature (Tg) decrease with increasing filler's volume fraction for the case of repulsive interaction between polymer and fillers and Tg weakly increase for attractive interaction.

Particle-in-a-box model of one-dimensional excitons in conjugated polymers

NASA Astrophysics Data System (ADS)

Pedersen, Thomas G.; Johansen, Per M.; Pedersen, Henrik C.

2000-04-01

A simple two-particle model of excitons in conjugated polymers is proposed as an alternative to usual highly computationally demanding quantum chemical methods. In the two-particle model, the exciton is described as an electron-hole pair interacting via Coulomb forces and confined to the polymer backbone by rigid walls. Furthermore, by integrating out the transverse part, the two-particle equation is reduced to one-dimensional form. It is demonstrated how essentially exact solutions are obtained in the cases of short and long conjugation length, respectively. From a linear combination of these cases an approximate solution for the general case is obtained. As an application of the model the influence of a static electric field on the electron-hole overlap integral and exciton energy is considered.

Polymer models of interphase chromosomes

PubMed Central

Vasquez, Paula A; Bloom, Kerry

2014-01-01

Clear organizational patterns on the genome have emerged from the statistics of population studies of fixed cells. However, how these results translate into the dynamics of individual living cells remains unexplored. We use statistical mechanics models derived from polymer physics to inquire into the effects that chromosome properties and dynamics have in the temporal and spatial behavior of the genome. Overall, changes in the properties of individual chains affect the behavior of all other chains in the domain. We explore two modifications of chain behavior: single chain motion and chain-chain interactions. We show that there is not a direct relation between these effects, as increase in motion, doesn’t necessarily translate into an increase on chain interaction. PMID:25482191

Determining heat loss from the surface of polymer films via modeling of experimental fluorescence thermometry

NASA Astrophysics Data System (ADS)

Firestone, Gabriel; Bochinski, Jason; Meth, Jeffrey; Clarke, Laura

Understanding of the heat transfer characteristics of a polymer during processing is critical to predicting and controlling the resulting properties and has been studied extensively in injection molding. As new methodologies for polymer processing are developed, such as photothermal heating, it is important to build an understanding of how heat transfer properties change under these novel conditions. By combining theoretical and experimental approaches, the thermal properties of photothermally heated polymer films were measured. The key idea is that by measuring the steady state temperature profile of a spot heated polymer film via a fluorescence probe (the temperature versus distance from the heated region) and fitting to a theoretical model, heat transfer coefficients can be extracted. We apply this approach to three different polymer systems, crosslinked epoxy, poly(methyl methacrylate) and poly(ethylene oxide) thin films with a range of thicknesses, under different heating laser intensities and with different resultant temperatures. We will discuss the resultant trends and extension of the model beyond a simple spot heating configuration. Support from National Science Foundation CMMI-1069108 and CMMI-1462966.

Blended polymer materials extractable with supercritical carbon dioxide

NASA Astrophysics Data System (ADS)

Cai, Mei

Supercritical carbon dioxide is drawing more and more attention because of its unique solvent properties along with being environmentally friendly. Historically most of the commercial interests of supercritical carbon dioxide extraction are in the food industry, pharmaceutical industry, environmental preservation and polymer processing. Recently attention has shifted from the extraction of relatively simple molecules to more complex systems with a much broader range of physical and chemical transformations. However the available data show that a lot of commercially valuable substances are not soluble in supercritical carbon dioxide due to their polar structures. This fact really limits the application of SCF extraction technology to much broader industrial applications. Therefore, the study of a polymer's solubility in a given supercritical fluid and its thermodynamic behavior becomes one of the most important research topics. The major objective of this dissertation is to develop a convenient and economic way to enhance the polymer's solubility in supercritical carbon dioxide. Further objective is to innovate a new process of making metal casting parts with blended polymer materials developed in this study. The key technique developed in this study to change a polymer's solubility in SCF CO2 is to thermally blend a commercially available and CO2 non-soluble polymer material with a low molecular weight CO2 soluble organic chemical that acts as a co-solute. The mixture yields a plastic material that can be completely solubilized in SCF CO2 over a range of temperatures and pressures. It also exhibits a variety of physical properties (strength, hardness, viscosity, etc.) depending on variations in the mixture ratio. The three organic chemicals investigated as CO2 soluble materials are diphenyl carbonate, naphthalene, and benzophenone. Two commercial polymers, polyethylene glycol and polystyrene, have been investigated as CO2 non-soluble materials. The chemical

Implementation of polarization processes in a charge transport model applied on poly(ethylene naphthalate) films

NASA Astrophysics Data System (ADS)

Hoang, M.-Q.; Le Roy, S.; Boudou, L.; Teyssedre, G.

2016-06-01

One of the difficulties in unravelling transport processes in electrically insulating materials is the fact that the response, notably charging current transients, can have mixed contributions from orientation polarization and from space charge processes. This work aims at identifying and characterizing the polarization processes in a polar polymer in the time and frequency-domains and to implement the contribution of the polarization into a charge transport model. To do so, Alternate Polarization Current (APC) and Dielectric Spectroscopy measurements have been performed on poly(ethylene naphthalene 2,6-dicarboxylate) (PEN), an aromatic polar polymer, providing information on polarization mechanisms in the time- and frequency-domain, respectively. In the frequency-domain, PEN exhibits 3 relaxation processes termed β, β* (sub-glass transitions), and α relaxations (glass transition) in increasing order of temperature. Conduction was also detected at high temperatures. Dielectric responses were treated using a simplified version of the Havriliak-Negami model (Cole-Cole (CC) model), using 3 parameters per relaxation process, these parameters being temperature dependent. The time dependent polarization obtained from the CC model is then added to a charge transport model. Simulated currents issued from the transport model implemented with the polarization are compared with the measured APCs, showing a good consistency between experiments and simulations in a situation where the response comes essentially from dipolar processes.

Modeling the Coupled Chemo-Thermo-Mechanical Behavior of Amorphous Polymer Networks.

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

Zimmerman, Jonathan A.; Nguyen, Thao D.; Xiao, Rui

2015-02-01

Amorphous polymers exhibit a rich landscape of time-dependent behavior including viscoelasticity, structural relaxation, and viscoplasticity. These time-dependent mechanisms can be exploited to achieve shape-memory behavior, which allows the material to store a programmed deformed shape indefinitely and to recover entirely the undeformed shape in response to specific environmental stimulus. The shape-memory performance of amorphous polymers depends on the coordination of multiple physical mechanisms, and considerable opportunities exist to tailor the polymer structure and shape-memory programming procedure to achieve the desired performance. The goal of this project was to use a combination of theoretical, numerical and experimental methods to investigate themore » effect of shape memory programming, thermo-mechanical properties, and physical and environmental aging on the shape memory performance. Physical and environmental aging occurs during storage and through exposure to solvents, such as water, and can significantly alter the viscoelastic behavior and shape memory behavior of amorphous polymers. This project – executed primarily by Professor Thao Nguyen and Graduate Student Rui Xiao at Johns Hopkins University in support of a DOE/NNSA Presidential Early Career Award in Science and Engineering (PECASE) – developed a theoretical framework for chemothermo- mechanical behavior of amorphous polymers to model the effects of physical aging and solvent-induced environmental factors on their thermoviscoelastic behavior.« less

Modeling and simulations of carbon nanotube (CNT) dispersion in water/surfactant/polymer systems

NASA Astrophysics Data System (ADS)

Uddin, Nasir Mohammad

An innovative multiscale (atomistic to mesoscale) model capable of predicting carbon nanotube (CNT) interactions and dispersion in water/surfactant/polymer systems was developed. The model was verified qualitatively with available experimental data in the literature. It can be used to computationally screen potential surfactants, solvents, polymers, and CNT with appropriate diameter and length to obtain improved CNT dispersion in aqueous medium. Thus the model would facilitate the reduction of time and cost required to produce CNT dispersed homogeneous solutions and CNT reinforced materials. CNT dispersion in any water/surfactant/polymer system depends on interactions between CNTs and surrounding molecules. Central to the study was the atomistic scale model which used the atomic structure of the surfactant, solvent, polymer, and CNT. The model was capable of predicting the CNT interactions in terms of potential of mean force (PMF) between CNTs under the influence of surrounding molecules in an aqueous solution. On the atomistic scale, molecular dynamics method was used to compute the PMF as a function of CNT separation and CNT alignment. An adaptive biasing force (ABF) method was used to speed up the calculations. Correlations were developed to determine the effective interactions between CNTs as a function of their any inter-atomic distance and orientation angle in water as well as in water/surfactant by fitting the calculated PMF data. On the mesoscale, the fitted PMF correlations were used as input in the Monte Carlo simulations to determine the degree of dispersion of CNTs in water and water/surfactant system. The distribution of CNT cluster size was determined for the CNTs dispersed in water with and without surfactant addition. The entropie and enthalpie contributions to the CNT interactions in water were determined to understand the dispersion mechanism of CNTs in water. The effects of CNT orientation, length, diameter, chirality and surfactant

Review of the chemistry and pharmacology of 7-Methyljugulone.

PubMed

Mbaveng, Armelle T; Kuete, Victor

2014-03-01

Naphthoquinone is a class of phenolic compounds derived from naphthalene. 7-Methyljuglone (7-MJ) is a naphthoquinone also known as ramentaceone or 6-Methyl-8-hydroxy-1,4-naphthoquinone or 5-Hydroxy-7-methyl-1,4-naphthoquinone or 7-Methyl-5-hydroxy-1,4-naphthoquinone or 5-Hydroxy-7-methyl-,1,4-naphtoquinone or 7-Methyl-5-hydroxynaphthalene-1,4-dione. This compound is a biologically active naphtoquinone, with a molecular weight of 188 g/mol mostly isolated in the genus Diospyros and Euclea. This review was aimed at providing available chemically and pharmacological data on 7-MJ. The chemical and pharmacological data were retrieved from the well-known scientific websites such as Pubmed, Google Scholar, Reaxys, Scirus, Scopus, Sciencedirect, Web-of-knowledge and Scifinder. 7-MJ was reported to have a variety of pharmacological activities such as antibacterial, antifungal, anticancer, antitubercular, anti-inflammatory and antiviral activities. The hemi-synthesis of the compound have been described. The present review pooled out together the knowledge on 7-MJ, and can serve as the start point for future research and valorization accomplishments.

Two new coordination polymers constructed by naphthalene-1,4-dicarboxylic acid and 2,4-diamino-6-methyl-triazine

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

Li, Yamin, E-mail: liyamin@henu.edu.cn; Xiao, Changyu; Zhang, Xudong

2013-08-15

Two new transition metal coordination complexes, ([MnO(nda)](H{sub 2}dmt)(H{sub 2}O)){sub n} (1), [Ag{sub 5}(nda){sub 2.5}(dmt)]{sub n} (2), (H{sub 2}nda=naphthalene-1,4-dicarboxylic acid, dmt=2,4-diamine-6-methyl-1,3,5-triazine) have been hydrothermally synthesized by the reactions of H{sub 2}nda and dmt with the homologous MnCl{sub 2}·4H{sub 2}O and AgNO{sub 3}, respectively, and characterized by single-crystal X-ray diffraction, IR spectra, elemental analysis, thermogravimetric analysis (TGA). The compound 1 exhibits a 3D network comprising 1D metal chain (MnO(CO{sub 2}){sub 2}){sub n} connected by the ligand nda{sup 2−}, featuring a four-connected uninodal diamond -like topology. In compound 2, it is firstly observed that decanuclear silver units as secondary building units to constructmore » 3D network by the ligands dmt and nda{sup 2−}, with a rare 2-nodal (3,8)-connected tfz-d topology ((4{sup 3}){sub 2}(4{sup 6}.6{sup 18}.8{sup 4})). The interactions within each Mn(II)—Mn(II) pair of compound 1 are antiferromagnetic (g=2.07, J=−1.42(1) cm{sup −1}, zj′=−0.73(2) cm{sup −1}). In addition, compound 2 exhibits photoluminescent property at about 472 nm (λ{sub ex}=394 nm). - Graphical abstract: Two new transition metal coordination complexes 1–2 have been hydrothermally synthesized and characterized by single-crystal X-ray diffraction, IR spectra, elemental analysis thermogravimetric analysis (TGA). Highlights: • The compound 1 exhibits a 3D network with four-connected uninodal diamond-like topology. • The first 3D network of 2 with a rare tfz-d topology consists of decanuclear silver clusters as secondary building units. • The magnetic measurement indicates the compound 1 shows antiferromagnetic interactions. • The photoluminescent property of 2 has been measured.« less

2,4-Dinitrotoluene dioxygenase from Burkholderia sp. strain DNT: similarity to naphthalene dioxygenase.

PubMed Central

Suen, W C; Haigler, B E; Spain, J C

1996-01-01

2,4-Dinitrotoluene (DNT) dioxygenase from Burkholderia sp. strain DNT catalyzes the initial oxidation of DNT to form 4-methyl-5-nitrocatechol (MNC) and nitrite. The displacement of the aromatic nitro group by dioxygenases has only recently been described, and nothing is known about the evolutionary origin of the enzyme systems that catalyze these reactions. We have shown previously that the gene encoding DNT dioxygenase is localized on a degradative plasmid within a 6.8-kb NsiI DNA fragment (W.-C. Suen and J. C. Spain, J. Bacteriol. 175:1831-1837, 1993). We describe here the sequence analysis and the substrate range of the enzyme system encoded by this fragment. Five open reading frames were identified, four of which have a high degree of similarity (59 to 78% identity) to the components of naphthalene dioxygenase (NDO) from Pseudomonas strains. The conserved amino acid residues within NDO that are involved in cofactor binding were also identified in the gene encoding DNT dioxygenase. An Escherichia coli clone that expressed DNT dioxygenase converted DNT to MNC and also converted naphthalene to (+)-cis-(1R,2S)-dihydroxy-1,2-dihydronaphthalene. In contrast, the E. coli clone that expressed NDO did not oxidize DNT. Furthermore, the enzyme systems exhibit similar broad substrate specificities and can oxidize such compounds as indole, indan, indene, phenetole, and acenaphthene. These results suggest that DNT dioxygenase and the NDO enzyme system share a common ancestor. PMID:8759857

Blob-Spring Model for the Dynamics of Ring Polymer in Obstacle Environment

NASA Astrophysics Data System (ADS)

Lele, Ashish K.; Iyer, Balaji V. S.; Juvekar, Vinay A.

2008-07-01

The dynamical behavior of cyclic macromolecules in a fixed obstacle (FO) environment is very different than the behavior of linear chains in the same topological environment; while the latter relax by a snake-like reptational motion from their chain ends the former can relax only by contour length fluctuations since they are endless. Duke, Obukhov and Rubinstein proposed a scaling model (the DOR model) to interpret the dynamical scaling exponents shown by Monte Carlo simulations of rings in a FO environment. We present a model (blob-spring model) to describe the dynamics of flexible and non-concatenated ring polymer in FO environment based on a theoretical formulation developed for the dynamics of an unentangled fractal polymer. We argue that the perpetual evolution of ring perimeter by the motion of contour segments results in an extra frictional load. Our model predicts self-similar dynamics with scaling exponents for the molecular weight dependence of diffusion coefficient and relaxation times that are in agreement with the scaling model proposed by Obukhov et al.

Experimental characterization and computational modeling of unimorph shape memory polymer actuators incorporating transverse curvature in the substrate

NASA Astrophysics Data System (ADS)

Cantrell, Jason T.

This document outlines in detail the research performed by applying shape memory polymers in a generic unimorph actuator configuration. A set of experiments designed to investigate the influence of transverse curvature, the relative widths of shape memory polymer and composite substrates, and shape memory polymer thickness on actuator recoverability after multiple thermo-mechanical cycles is presented in detail. A theoretical model of the moment required to maintain shape fixity with minimal shape retention loss was developed and experimentally validated for unimorph composite actuators of varying cross-sectional areas. Theoretical models were also developed and evaluated to determine the relationship between the materials neutral axes and thermal stability during a thermo-mechanical cycle. Research was conducted on the incorporation of shape memory polymers on micro air vehicle wings to maximize shape fixity and shape recoverability while minimizing the volume of shape memory polymer on the wing surface. Applications based research also included experimentally evaluating the feasibility of shape memory polymers on deployable satellite antenna ribs both with and without resistance heaters which could be utilized to assist in antenna deployment.

Thalassospira permensis sp. nov., a new terrestrial halotolerant bacterium isolated from a naphthalene-utilizing microbial consortium.

PubMed

Plotnikova, E G; Anan'ina, L N; Krausova, V I; Ariskina, E V; Prisyazhnaya, N V; Lebedev, A T; Demakov, V A; Evtushenko, L I

2011-01-01

A halotolerant bacterium, strain SMB34T, was isolated from a naphthalene-utilizing bacterial consortium obtained from primitive technogeneous soil (Vrkhnekamsk salt deposit, Perm region, Russia) by enrichment procedure. The strain itself was unable to degrade naphthalene and grew at NaCl concentrations up to 11% (w/v). The 16S rRNA-based phylogenetic analysis showed that the strain belongs to the genus Thalassospira. The DNA-DNA hybridization values between SMB34T and the type strains of phylogenetically closest species (T. xiamenensis, T. profundimaris and T. tepidiphila) did not exceed 50%. The novel strain could be distinguished from the above species by the cell motility, MALDI/TOF mass spectra of whole cells and a range of physiological and biochemical characteristics. SMB34T also considerably differs from the recently described species T. xianhensis, with the most striking differences in the DNA G + C content (53.7 +/- 1.0 vs. 61.2 +/- 1.0 mol.%) and predominant ubiquinones (Q-10 vs. Q-9). The data obtained suggest strain SMB34T (=VKM B-2527T = NBRC 106175T), designated as the type strain, represents a novel species, named Thalassospira permensis sp. nov.

Noncatalytic hydrogenation of naphthalene in nanosized membrane reactors with accumulated hydrogen and controlled adjustment of their reaction zone volumes

NASA Astrophysics Data System (ADS)

Soldatov, A. P.

2017-05-01

As part of ongoing studies aimed at designing the next generation of nanosized membrane reactors (NMRs) with accumulated hydrogen, the noncatalytic hydrogenation of naphthalene in pores of ceramic membranes (TRUMEM ultrafiltration membranes with D av = 50 and 90 nm) is performed for the first time, using hydrogen preadsorbed in a hybrid carbon nanostructure: mono- and multilayered oriented carbon nanotubes with graphene walls (OCNTGs) that form on inner pore surfaces. In this technique, the reaction proceeds in the temperature range of 330-390°C at contact times of 10-16 h. The feedstock is an 8% naphthalene solution in decane. The products are analyzed via chromatography on a quartz capillary column coated with polydimethylsiloxane (SE-30). It is established for the first time that in NMRs, the noncatalytic hydrogenation of naphthalene occurs at 370-390°C, forming 1,2,3,4-tetrahydronaphthalene in amounts of up to 0.61%. The rate constants and activation energy (123.5 kJ/mol) of the noncatalytic hydrogenation reaction are determined for the first time. The possibility of designing an NMR with an adjustable reaction zone volume is explored. Changes in the pore structure of the membranes after their modification with pyrocarbon nanosized crystallites (PNCs) are therefore studied as well. It is shown that lengthening the process time reduces pore size: within 23 h after the deposition of PNCs, the average pore radius ( r av) falls from 25 to 3.1 nm. The proposed approach would allow us to design nanoreactors of molecular size and conduct hydrogenation reactions within certain guidelines to synthesize new chemical compounds.

Thermal modelling of Li-ion polymer battery for electric vehicle drive cycles

NASA Astrophysics Data System (ADS)

Chacko, Salvio; Chung, Yongmann M.

2012-09-01

Time-dependent, thermal behaviour of a lithium-ion (Li-ion) polymer cell has been modelled for electric vehicle (EV) drive cycles with a view to developing an effective battery thermal management system. The fully coupled, three-dimensional transient electro-thermal model has been implemented based on a finite volume method. To support the numerical study, a high energy density Li-ion polymer pouch cell was tested in a climatic chamber for electric load cycles consisting of various charge and discharge rates, and a good agreement was found between the model predictions and the experimental data. The cell-level thermal behaviour under stressful conditions such as high power draw and high ambient temperature was predicted with the model. A significant temperature increase was observed in the stressful condition, corresponding to a repeated acceleration and deceleration, indicating that an effective battery thermal management system would be required to maintain the optimal cell performance and also to achieve a full battery lifesapn.

Three-Dimensional (3D) Printing of Polymer-Metal Hybrid Materials by Fused Deposition Modeling.

PubMed

Fafenrot, Susanna; Grimmelsmann, Nils; Wortmann, Martin; Ehrmann, Andrea

2017-10-19

Fused deposition modeling (FDM) is a three-dimensional (3D) printing technology that is usually performed with polymers that are molten in a printer nozzle and placed line by line on the printing bed or the previous layer, respectively. Nowadays, hybrid materials combining polymers with functional materials are also commercially available. Especially combinations of polymers with metal particles result in printed objects with interesting optical and mechanical properties. The mechanical properties of objects printed with two of these metal-polymer blends were compared to common poly (lactide acid) (PLA) printed objects. Tensile tests and bending tests show that hybrid materials mostly containing bronze have significantly reduced mechanical properties. Tensile strengths of the 3D-printed objects were unexpectedly nearly identical with those of the original filaments, indicating sufficient quality of the printing process. Our investigations show that while FDM printing allows for producing objects with mechanical properties similar to the original materials, metal-polymer blends cannot be used for the rapid manufacturing of objects necessitating mechanical strength.

Modeling solvent evaporation during thin film formation in phase separating polymer mixtures

DOE PAGES

Cummings, John; Lowengrub, John S.; Sumpter, Bobby G.; ...

2018-02-09

Preparation of thin films by dissolving polymers in a common solvent followed by evaporation of the solvent has become a routine processing procedure. However, modeling of thin film formation in an evaporating solvent has been challenging due to a need to simulate processes at multiple length and time scales. In this paper, we present a methodology based on the principles of linear non-equilibrium thermodynamics, which allows systematic study of various effects such as the changes in the solvent properties due to phase transformation from liquid to vapor and polymer thermodynamics resulting from such solvent transformations. The methodology allows for themore » derivation of evaporative flux and boundary conditions near each surface for simulations of systems close to the equilibrium. We apply it to study thin film microstructural evolution in phase segregating polymer blends dissolved in a common volatile solvent and deposited on a planar substrate. Finally, effects of the evaporation rates, interactions of the polymers with the underlying substrate and concentration dependent mobilities on the kinetics of thin film formation are studied.« less

Modeling solvent evaporation during thin film formation in phase separating polymer mixtures

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

Cummings, John; Lowengrub, John S.; Sumpter, Bobby G.

Preparation of thin films by dissolving polymers in a common solvent followed by evaporation of the solvent has become a routine processing procedure. However, modeling of thin film formation in an evaporating solvent has been challenging due to a need to simulate processes at multiple length and time scales. In this paper, we present a methodology based on the principles of linear non-equilibrium thermodynamics, which allows systematic study of various effects such as the changes in the solvent properties due to phase transformation from liquid to vapor and polymer thermodynamics resulting from such solvent transformations. The methodology allows for themore » derivation of evaporative flux and boundary conditions near each surface for simulations of systems close to the equilibrium. We apply it to study thin film microstructural evolution in phase segregating polymer blends dissolved in a common volatile solvent and deposited on a planar substrate. Finally, effects of the evaporation rates, interactions of the polymers with the underlying substrate and concentration dependent mobilities on the kinetics of thin film formation are studied.« less

Modelling Viscoelastic Behaviour of Polymer by A Mixed Velocity, Displacement Formulation - Numerical and Experimental Results

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

Pham, VT.; Silva, L.; Digonnet, H.

2011-05-04

The objective of this work is to model the viscoelastic behaviour of polymer from the solid state to the liquid state. With this objective, we perform experimental tensile tests and compare with simulation results. The chosen polymer is a PMMA whose behaviour depends on its temperature. The computation simulation is based on Navier-Stokes equations where we propose a mixed finite element method with an interpolation P1+/P1 using displacement (or velocity) and pressure as principal variables. The implemented technique uses a mesh composed of triangles (2D) or tetrahedra (3D). The goal of this approach is to model the viscoelastic behaviour ofmore » polymers through a fluid-structure coupling technique with a multiphase approach.« less

Particle-in-a-box model of exciton absorption and electroabsorption in conjugated polymers

NASA Astrophysics Data System (ADS)

Pedersen, Thomas G.

2000-12-01

The recently proposed particle-in-a-box model of one-dimensional excitons in conjugated polymers is applied in calculations of optical absorption and electroabsorption spectra. It is demonstrated that for polymers of long conjugation length a superposition of single exciton resonances produces a line shape characterized by a square-root singularity in agreement with experimental spectra near the absorption edge. The effects of finite conjugation length on both absorption and electroabsorption spectra are analyzed.

Chain confinement, phase transitions, and lamellar structure in semicrystalline polymers, polymer blends and polymer nanocomposites

NASA Astrophysics Data System (ADS)

Chen, Huipeng

Recent studies suggest that there are three phase fractions in semicrystalline polymers, the crystalline, the mobile amorphous and the rigid amorphous phases. Due to the distinct properties of the rigid amorphous fraction, RAF, it has been investigated for more than twenty years. In this thesis, a general method using quasi-isothermal temperature-modulated differential scaning calorimetry, DSC, is provided for the first time to obtain the temperature dependent RAF and the other two fractions, crystalline fraction and mobile amorphous fraction, MAF. For poly(ethylene terephthalate), PET, our results show RAF was vitrified during quasi-isothermal cooling after crystallization had been completed and became totally devitrified during quasi-isothermal heating before the start of melting. Several years after people initially discovered the existence of RAF, another issue arose relating to the physical location of RAF and mobile amorphous fraction, MAF, within a lamellar stack model. Two very different models to describe the location of RAF were proposed. In the Heterogeneous Stack Model, HET, RAF is located outside the lamellar stacks. In the Homogeneous Stack Model, HSM, RAF was located inside the lamellar stacks. To determine the lamellar structure of semicrystalline polymers comprising three phase, a general method is given in this thesis by using a combination of the DSC and small angle X-ray scattering, SAXS techniques. It has been applied to Nylon 6, isotactic polystyrene, iPS, and PET. It was found for all of these materials, the HSM model is correct to describe the lamellar structure. In addition to the determination of lamellar structures, this method can also provide the exact fraction of MAF inside and outside lamellar stacks for binary polymer blends. For binary polymer blends, MAF, normally is located partially inside and partially outside the lamellar stacks. However, the quantification of the MAF inside and outside the lamellar stacks has now been provided

Abundance of Dioxygenase Genes Similar to Ralstonia sp. Strain U2 nagAc Is Correlated with Naphthalene Concentrations in Coal Tar-Contaminated Freshwater Sediments

PubMed Central

Dionisi, Hebe M.; Chewning, Christopher S.; Morgan, Katherine H.; Menn, Fu-Min; Easter, James P.; Sayler, Gary S.

2004-01-01

We designed a real-time PCR assay able to recognize dioxygenase large-subunit gene sequences with more than 90% similarity to the Ralstonia sp. strain U2 nagAc gene (nagAc-like gene sequences) in order to study the importance of organisms carrying these genes in the biodegradation of naphthalene. Sequencing of PCR products indicated that this real-time PCR assay was specific and able to detect a variety of nagAc-like gene sequences. One to 100 ng of contaminated-sediment total DNA in 25-μl reaction mixtures produced an amplification efficiency of 0.97 without evident PCR inhibition. The assay was applied to surficial freshwater sediment samples obtained in or in close proximity to a coal tar-contaminated Superfund site. Naphthalene concentrations in the analyzed samples varied between 0.18 and 106 mg/kg of dry weight sediment. The assay for nagAc-like sequences indicated the presence of (4.1 ± 0.7) × 103 to (2.9 ± 0.3) × 105 copies of nagAc-like dioxygenase genes per μg of DNA extracted from sediment samples. These values corresponded to (1.2 ± 0.6) × 105 to (5.4 ± 0.4) × 107 copies of this target per g of dry weight sediment when losses of DNA during extraction were taken into account. There was a positive correlation between naphthalene concentrations and nagAc-like gene copies per microgram of DNA (r = 0.89) and per gram of dry weight sediment (r = 0.77). These results provide evidence of the ecological significance of organisms carrying nagAc-like genes in the biodegradation of naphthalene. PMID:15240274

Structure, spectroscopic analyses (FT-IR and NMR), vibrational study, chemical reactivity and molecular docking study on 3,3'-((4-(trifluoromethyl)phenyl)methylene)bis(2-hydroxynaphthalene-1,4-dione), a promising anticancerous bis-lawsone derivative

NASA Astrophysics Data System (ADS)

Yadav, Krishna Kant; Kumar, Abhishek; Kumar, Amarendra; Misra, Neeraj; Brahmachari, Goutam

2018-02-01

Lawsone (2-hydroxy-1,4-naphthoquinone)has been evaluated to possess a wide range of biological and pharmacological activities. The interesting structural pattern of lawsone coupled with its so-called multifaceted pharmacological potential have made this scaffolds useful in certain chemical processes, particularly in synthesizing ligands for metal complexations, and also few of its derivatives have shown a number of biological activities. The equilibrium geometry of 3,3‧-((4-(trifluoromethyl)phenyl)methylene)bis(2-hydroxynaphthalene-1,4-dione) (1; TPMHD), a promising anticancerous lawsone derivative, has been determined and analyzed at DFT method employingB3LYP/6-311++G(d,p) level of theory. The reactivity descriptors such as Fukui functions and HOMO-LUMO gap are calculated and discussed. The infrared spectra of TPMHD(1) are calculated and compared with the experimentally observed ones. Moreover, 1H and 13C NMR spectra have been calculated by using the gauge independent atomic orbital method. The docking studies reveal that the TPMHD has strong binding affinity toward target protein 2SHP. Thus the compound has a possible use as a drug in cancer therapy. The study suggests further investigation on TPMHD for their in-depth biological and pharmaceutical importance.

A model and simulation of fast space charge pulses in polymers

NASA Astrophysics Data System (ADS)

Lv, Zepeng; Rowland, Simon M.; Wu, Kai

2017-11-01

The transport of space charge packets across polyethylene and epoxy resin in high electric fields has been characterized as fast or slow depending on packet mobility. Several explanations for the formation and transport of slow space charge packets have been proposed, but the origins of fast space charge pulses, with mobilities above 10-11 m2 V-1 s-1, are unclear. In one suggested model, it is assumed that the formation of fast charge pulses is due to discontinuous electromechanical compression and charge injection at the electrode-insulation interface, and their transport is related to corresponding relaxation processes. In that model, charges travel as a pulse because of group polarization. This paper provides an alternative model based on the reduction of charge carrier activation energy due to charge density triggered polymer chain movement and subsequent chain relaxation times. The generation and transport of fast charge pulses are readily simulated by a bipolar charge transport model with three additional parameters: reduced activation energy, charge density threshold, and chain relaxation time. Such a model is shown to reproduce key features of fast space charge pulses including speed, duration, repetition rate and pulse size. This model provides the basis for a deep understanding of the physical origins of fast space charge pulses in polymers.

An affine microsphere approach to modeling strain-induced crystallization in rubbery polymers

NASA Astrophysics Data System (ADS)

Nateghi, A.; Dal, H.; Keip, M.-A.; Miehe, C.

2018-01-01

Upon stretching a natural rubber sample, polymer chains orient themselves in the direction of the applied load and form crystalline regions. When the sample is retracted, the original amorphous state of the network is restored. Due to crystallization, properties of rubber change considerably. The reinforcing effect of the crystallites stiffens the rubber and increases the crack growth resistance. It is of great importance to understand the mechanism leading to strain-induced crystallization. However, limited theoretical work has been done on the investigation of the associated kinetics. A key characteristic observed in the stress-strain diagram of crystallizing rubber is the hysteresis, which is entirely attributed to strain-induced crystallization. In this work, we propose a micromechanically motivated material model for strain-induced crystallization in rubbers. Our point of departure is constructing a micromechanical model for a single crystallizing polymer chain. Subsequently, a thermodynamically consistent evolution law describing the kinetics of crystallization on the chain level is proposed. This chain model is then incorporated into the affine microsphere model. Finally, the model is numerically implemented and its performance is compared to experimental data.

Mechanisms of Morphology Development and Control in Polymer- Polymer Blends

NASA Astrophysics Data System (ADS)

Macosko, Christopher W.

1998-03-01

Compatibilizers?" accepted for publication by Journal of Polymer Science, Polymer Physics Edition, 1997. Levitt, L. and C. W. Macosko, "Extensional Rheometry of Polymer Multilayers: A Sensitive Probe of Interfaces," J. Rheol, 41, 3, 671-685, (1997). Levitt, L., C.W. Macosko and S.D. Pearson, "Influence of Normal Stress Difference on Polymer Drop Deformation," Polym. Eng. Sci., 36, Part 12, 1647-1655 (1996). Nakayama, A., T. Inoue, A. Hirao, P. Guegan, A. Khandpur, and C. W. Macosko, "Compatibilization of Blends: Effect of Reaction Rate," PPS Proceedings, Sorrento, May 1996. Levitt, L., "Microlayer Morphology Via Polymer Melt Processing, Ph.D. Thesis, Department of Chemical Engineering & Materials Science, University of Minnesota, 1997. Orr, C. A., A. Adedeji, A. Hirao, F. S. Bates, and C. W. Macosko, "Flow-Induced Reactive Self-Assembly", Macromolecules, 30, 4, 1243-1246, (1997). Orr, C. A., "Reactive Compatibilization of Polymer Blends," Ph.D. Thesis, Department of Chemical Engineering & Materials Science, University of Minnesota, 1997. Scott, C. E., and C. W. Macosko, "Morphology Development During the Initial Stages of Polymer-Polymer Blending," Polymer, 36, 461-470 (1995). Scott, C. E. and C. W. Macosko, "Model Experiments Concerning Morphology Development During the Initial Stages of Polymer Blending," Polymer Bulletin 26, 341- 348 (1991). Sundararaj, U., C. K. Shih, and C. W. Macosko, "Evidence For Inversion of Phase Continuity During Morphology Development in Polymer Blending," Polymer Eng. and Sci., 36, 1769-1781 (1996). Sundararaj, U., and C. W. Macosko, "Drop Breakup and Coalescence in Polymer Blends: The Effects of Concentration and Compatibilization, Macromolecules, 28, 2647-2657 (1995). Sundararaj, U., Y. Dori and C. W. Macosko, "Sheet Formation in Immiscible Polymer Blends: Model Experiments on Initial Blend Morphology," Polymer, 36, 1957-1968 (1995). Sundararaj, U., C. W. Macosko, A. Nakayama, and T. Inoue, "Milligrams to Kilograms: An Evaluation of Mixers for

A multi-species exchange model for fully fluctuating polymer field theory simulations.

PubMed

Düchs, Dominik; Delaney, Kris T; Fredrickson, Glenn H

2014-11-07

Field-theoretic models have been used extensively to study the phase behavior of inhomogeneous polymer melts and solutions, both in self-consistent mean-field calculations and in numerical simulations of the full theory capturing composition fluctuations. The models commonly used can be grouped into two categories, namely, species models and exchange models. Species models involve integrations of functionals that explicitly depend on fields originating both from species density operators and their conjugate chemical potential fields. In contrast, exchange models retain only linear combinations of the chemical potential fields. In the two-component case, development of exchange models has been instrumental in enabling stable complex Langevin (CL) simulations of the full complex-valued theory. No comparable stable CL approach has yet been established for field theories of the species type. Here, we introduce an extension of the exchange model to an arbitrary number of components, namely, the multi-species exchange (MSE) model, which greatly expands the classes of soft material systems that can be accessed by the complex Langevin simulation technique. We demonstrate the stability and accuracy of the MSE-CL sampling approach using numerical simulations of triblock and tetrablock terpolymer melts, and tetrablock quaterpolymer melts. This method should enable studies of a wide range of fluctuation phenomena in multiblock/multi-species polymer blends and composites.

Modelization of three-layered polymer coated steel-strip ironing process using a neural network

NASA Astrophysics Data System (ADS)

Sellés, M. A.; Schmid, S. R.; Sánchez-Caballero, S.; Seguí, V. J.; Reig, M. J.; Pla, R.

2012-04-01

An alternative to the traditional can manufacturing process is to use plastic laminated rolled steels as base stocks. This material consist of pre-heated steel coils that are sandwiched between one or two sheets of polymer. The heated sheets are then immediately quenched, which yields a strong bond between the layers. Such polymer-coated steels were investigated by Jaworski [1,2] and Sellés [3], and found to be suitable for ironing with carefully controlled conditions. A novel multi-layer polymer coated steel has been developed for container applications. This material presents an interesting extension to previous research on polymer laminated steel in ironing, and offers several advantages over the previous material (Sellés [3]). This document shows a modelization for the ironing process (the most crucial step in can manufacturing) done by using a neural network

The effect of polychlorinated naphthalenes and tributyltin on the occurrence of aberrant nuclei in erythroid cells of medaka

USGS Publications Warehouse

Talykina, Melaniya G.; Papoulias, Diana M.; Allert, J. Alan; Izyuov, Y.U.; Villalobos, Sergio A.; Giesy, John P.; Tillitt, Donald E.

2003-01-01

The micronucleus test using erythrocytes of the peripheral blood of fish is often conducted to evaluate the genotoxic effects of pollutants under experimental and natural conditions. This report presents information on the production of micronuclei and other nuclear anomalies in erythrocytes of medaka (Oryzias latipes) exposed to three polychlorinated naphthalene (PCN) formulations (Halowaxes 1014, 1031 and 1051) or tributyltin (TBT). Three types of deviation in the morphology of interphase nuclei were observed in medaka erythrocytes: micronuclei, nuclei fragmented into two equal or unequal parts, and nuclei at different stages of invagination. The number of erythrocytes with nuclear anomalies typically increased after chemical exposure. However, differential dose-response patterns were observed with exposures to PCNs or TBT. Polychlorinated naphthalenes caused genotoxicity, while TBT caused an amitotic effect. Gender did not influence the frequency of nuclear anomalies. This is the first report on the application of the piscine micronuclear test with medaka and is the first study that investigated the potential for detecting micronuclei in erythrocytes from adult medaka exposed in ovo to mutagens.

Effects of cadmium, naphthalene, and DDVP on gut carbohydrases activity in bream (Abramis brama L. ) and Mozambique tilapia (Oreochromis mossambicus Peters)

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

Golovanova, I.L.; Chuiko, G.M.; Pavlov, D.F.

1994-03-01

Previous research has shown that sublethal concentrations of cadmium, naphthalene and dichlorvos (DDVP) decreased growth rates in bream and Mozambique tilapia. One of the factors known to affect fish growth is the activity of gut digestive enzymes such as of lipases, proteases, carbohydrases. We assumed that toxicant-induced inhibition of the digestive enzyme activity and, consequently, the impaired digestion of food may contribute to the reduction of growth in fish exposed to toxicants. However, the influence of toxicants on digestive enzyme activities is poorly studied. The contribution of toxicant-induced changes of digestive enzymes activity to growth rate retardation in exposed fishmore » remains unknown. The goal of this study was to examine the influence of an organophosphorus insecticide DDVP, a polyaromatic hydrocarbon naphthalene, and a metal cadmium on fish gut carbohydrase (CH) activity. 14 refs., 2 tabs.« less

Three-Dimensional (3D) Printing of Polymer-Metal Hybrid Materials by Fused Deposition Modeling

PubMed Central

Fafenrot, Susanna; Grimmelsmann, Nils; Wortmann, Martin

2017-01-01

Fused deposition modeling (FDM) is a three-dimensional (3D) printing technology that is usually performed with polymers that are molten in a printer nozzle and placed line by line on the printing bed or the previous layer, respectively. Nowadays, hybrid materials combining polymers with functional materials are also commercially available. Especially combinations of polymers with metal particles result in printed objects with interesting optical and mechanical properties. The mechanical properties of objects printed with two of these metal-polymer blends were compared to common poly (lactide acid) (PLA) printed objects. Tensile tests and bending tests show that hybrid materials mostly containing bronze have significantly reduced mechanical properties. Tensile strengths of the 3D-printed objects were unexpectedly nearly identical with those of the original filaments, indicating sufficient quality of the printing process. Our investigations show that while FDM printing allows for producing objects with mechanical properties similar to the original materials, metal-polymer blends cannot be used for the rapid manufacturing of objects necessitating mechanical strength. PMID:29048347

Modeling the effect of nano-sized polymer particles on the properties of lipid membranes

NASA Astrophysics Data System (ADS)

Rossi, Giulia; Monticelli, Luca

2014-12-01

The interaction between polymers and biological membranes has recently gained significant interest in several research areas. On the biomedical side, dendrimers, linear polyelectrolytes, and neutral copolymers find application as drug and gene delivery agents, as biocidal agents, and as platforms for biological sensors. On the environmental side, plastic debris is often disposed of in the oceans and gets degraded into small particles; therefore concern is raising about the interaction of small plastic particles with living organisms. From both perspectives, it is crucial to understand the processes driving the interaction between polymers and cell membranes. In recent times progress in computer technology and simulation methods has allowed computational predictions on the molecular mechanism of interaction between polymeric materials and lipid membranes. Here we review the computational studies on the interaction between lipid membranes and different classes of polymers: dendrimers, linear charged polymers, polyethylene glycol (PEG) and its derivatives, polystyrene, and some generic models of polymer chains. We conclude by discussing some of the technical challenges in this area and future developments.

Characterization and modeling of viscoelastic behavior of carbon nanotube reinforced polymers: The influence of interphase and nanotube morphology

NASA Astrophysics Data System (ADS)

Liu, Hua

The addition of nanoparticles into polymer materials has been observed to dramatically change the mechanical, thermal, electrical, and diffusion properties of the host polymers, promising a novel class of polymer matrix composite materials with superior properties and added functionalities that are ideal candidates in many applications, including aerospace, automobile, medical devices, and sporting goods. Understanding the behavior and underlying mechanisms of these polymer nanocomposites is critical. The research work presented in this dissertation represents one of the initial efforts in the long journey pursuing the ultimate understanding of nanoparticle reinforced polymer systems. Particular focal points are experimental evaluation and the development of appropriate modeling methods to capture the influence of the interphase on the overall viscoelastic behavior of carbon nanotube reinforced polymer nanocomposites. The first portion of this dissertation study investigates the viscoelastic behavior of MWCNT based PMMA nanocomposites, which complements our previous study of SWCNT/PMMA systems to confirm functionalization of nanotubes as an effective way to manipulate the interaction between nanotube and polymers and control the properties of the interphase region forming around the nanotubes and consequently change the overall performance of nanotube based polymer nanocomposites. In the second portion of this dissertation, we present a novel hybrid numerical-analytical modeling method that is capable of predicting viscoelastic behavior of multiphase polymer nanocomposites, in which the nanoscopic fillers can assume complex configurations. By combining the finite element technique and a micromechanical approach (particularly, the Mori-Tanaka method) with local phase properties, this method operates at low computational cost and effectively accounts for the influence of the interphase as well as in situ nanoparticle morphology. This modeling method is implemented

Precise control of polymer coated nanopores by nanoparticle additives: Insights from computational modeling

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

Eskandari Nasrabad, Afshin; Coalson, Rob D.; Jasnow, David

Polymer-nanoparticle composites are a promising new class of materials for creation of controllable nano-patterned surfaces and nanopores. We use coarse-grained molecular dynamics simulations augmented with analytical theory to study the structural transitions of surface grafted polymer layers (brushes) induced by infiltration of nanoparticles that are attracted to the polymers in the layer. We systematically compare two different polymer brush geometries: one where the polymer chains are grafted to a planar surface and the other where the chains are grafted to the inside of a cylindrical nanochannel. We perform a comprehensive study of the effects of the material parameters such asmore » the polymer chain length, chain grafting density, nanoparticle size, strength of attraction between nanoparticles and polymer monomers, and, in the case of the cylindrically grafted brush, the radius of the cylinder. We find a very general behavioral motif for all geometries and parameter values: the height of the polymer brush is non-monotonic in the nanoparticle concentration in solution. As the nanoparticle concentration increases, the brush height first decreases and after passing through a minimum value begins to increase, resulting in the swelling of the nanoparticle infused brush. These morphological features may be useful for devising tunable “smart” nano-devices whose effective dimensions can be reversibly and precisely adjusted by changing the nanoparticle concentration in solution. The results of approximate Self-Consistent Field Theory (SCFT) calculations, applicable in the regime of strong brush stretching, are compared to the simulation results. The SCFT calculations are found to be qualitatively, even semi-quantitatively, accurate when applied within their intended regime of validity, and provide a useful and efficient tool for modeling such materials.« less

Polymer Brushes under High Load

PubMed Central

Balko, Suzanne M.; Kreer, Torsten; Costanzo, Philip J.; Patten, Tim E.; Johner, Albert; Kuhl, Tonya L.; Marques, Carlos M.

2013-01-01

Polymer coatings are frequently used to provide repulsive forces between surfaces in solution. After 25 years of design and study, a quantitative model to explain and predict repulsion under strong compression is still lacking. Here, we combine experiments, simulations, and theory to study polymer coatings under high loads and demonstrate a validated model for the repulsive forces, proposing that this universal behavior can be predicted from the polymer solution properties. PMID:23516470

Polymers imprinted with PAH mixtures--comparing fluorescence and QCM sensors.

PubMed

Lieberzeit, Peter A; Halikias, Konstantin; Afzal, Adeel; Dickert, Franz L

2008-12-01

Molecular imprinting with binary mixtures of different polycyclic aromatic hydrocarbons (PAH) is a tool for design of chemically highly sensitive layers for detection of these analytes. Sensor responses increase by one order of magnitude compared with layers imprinted with one type of template. Detection limits, e.g. for pyrene, reach down to 30 ng L(-1) in water, as could be observed with a naphthalene and pyrene-imprinted polyurethane. Comparing sensor characteristics obtained by QCM and fluorescence reveals different saturation behaviours indicating that, first, single PAH molecules occupy the interaction centres followed by gradual excimer incorporation at higher concentrations finally leading to substantial quenching, when all accessible cavities are occupied. The plateau in the mass-sensitive measurements suggests that up to 80% of the cavities generated in the MIP are re-occupied. Displacement measurements between chrysene and pyrene revealed that for imprinted layers with very high pyrene sensitivities the signals of both PAH are additive, whereas in materials with lower pyrene uptake the two analytes replace each other in the interaction sites of the polymer.

Concentration-dependent antagonistic persuasion of SDS and naphthalene derivatives on the fibrillation of stem bromelain.

PubMed

Qadeer, Atiyatul; Ahmad, Ejaz; Zaman, Masihuz; Khan, Mohd Wasif; Khan, Javed Masood; Rabbani, Gulam; Tarique, Khaja Faisal; Sharma, Gaurav; Gourinath, Samudrala; Nadeem, Sajid; Badr, Gamal; Khan, Rizwan Hasan

2013-12-01

Sodium dodecyl sulfate, a biological membrane mimetic, can be used to study the conversion of globular proteins into amyloid fibrils in vitro. Using multiple approaches, the effect of SDS was examined on stem bromelain (SB), a widely recognized therapeutic protein. SB is known to exist as a partially folded intermediate at pH 2.0, situation also encountered in the gastrointestinal tract (its site of absorption). In the presence of sub-micellar SDS concentration (500-1000 μM), this intermediate was found to exhibit great propensity to form large-sized β-sheeted aggregates with fibrillar morphology, the hall marks of amyloid structure. We also observed inhibition of fibrillation by two naphthalene-based compounds, ANS and bis-ANS. While bis-ANS significantly inhibited fibril formation at 50 μM, ANS did so at relatively higher concentration (400 μM). Alcohols, but not salts, were found to weaken the inhibitory action of these compounds suggesting the possible involvement of hydrophobic interactions in their binding to protein. Besides, isothermal titration calorimetry and molecular docking studies suggested that inhibition of fibrillation by these naphthalene derivatives is mediated not just through hydrophobic forces, but also by disruption of π-π interactions between the aromatic residues together with the inter-polypeptide chain repulsion among negatively charged ANS/bis-ANS bound SB. Copyright © 2013 Elsevier Inc. All rights reserved.

Diffusion of residual monomer in polymer resins.

PubMed Central

Piver, W T

1976-01-01

A simplified mathematical model which made use of Fick's laws of diffusion written in spherical coordinates was developed to describe the rate of diffusion of residual monomers from polymer resins. The properties of the monomer-polymer system which influenced the amount of monomer remaining in the polymer as a function of time were the diffusivity and solubility of the monomer in the polymer, and the particle size of the polymer resin. This model was used to analyze literature data on the diffusion of residual vinyl chloride monomer in polyvinyl chloride resins made by the suspension process. It was concluded that particle size of the resin was a significant parameter which should be taken advantage of in process equipment designed to remove residual monomer from PVC resins. The diffusivity of the monomer in the polymer was a function of the solubility of the monomer in the polymer. Monomer solubility can be determined from Henry's law. It was suggested that this model could be adapted to describe diffusion of monomers from any monomer-polymer system, and would be a useful approach to modeling the transport of nonreactive chemical additives from plastics. PMID:1026410

Polarization and switching properties of holographic polymer-dispersed liquid-crystal gratings. I. Theoretical model

NASA Astrophysics Data System (ADS)

Sutherland, Richard L.

2002-12-01

Polarization properties and electro-optical switching behavior of holographic polymer-dispersed liquid-crystal (HPDLC) reflection and transmission gratings are studied. A theoretical model is developed that combines anisotropic coupled-wave theory with an elongated liquid-crystal-droplet switching model and includes the effects of a statistical orientational distribution of droplet-symmetry axes. Angle- and polarization-dependent switching behaviors of HPDLC gratings are elucidated, and the effects on dynamic range are described. A new type of electro-optical switching not seen in ordinary polymer-dispersed liquid crystals, to the best of the author's knowledge, is presented and given a physical interpretation. The model provides valuable insight to the physics of these gratings and can be applied to the design of HPDLC holographic optical elements.

Mechanical Properties of Polymers.

ERIC Educational Resources Information Center

Aklonis, J. J.

1981-01-01

Mechanical properties (stress-strain relationships) of polymers are reviewed, taking into account both time and temperature factors. Topics include modulus-temperature behavior of polymers, time dependence, time-temperature correspondence, and mechanical models. (JN)

Application of activated barrier hopping theory to viscoplastic modeling of glassy polymers

NASA Astrophysics Data System (ADS)

Sweeney, J.; Spencer, P. E.; Vgenopoulos, D.; Babenko, M.; Boutenel, F.; Caton-Rose, P.; Coates, P. D.

2018-05-01

An established statistical mechanical theory of amorphous polymer deformation has been incorporated as a plastic mechanism into a constitutive model and applied to a range of polymer mechanical deformations. The temperature and rate dependence of the tensile yield of PVC, as reported in early studies, has been modeled to high levels of accuracy. Tensile experiments on PET reported here are analyzed similarly and good accuracy is also achieved. The frequently observed increase in the gradient of the plot of yield stress against logarithm of strain rate is an inherent feature of the constitutive model. The form of temperature dependence of the yield that is predicted by the model is found to give an accurate representation. The constitutive model is developed in two-dimensional form and implemented as a user-defined subroutine in the finite element package ABAQUS. This analysis is applied to the tensile experiments on PET, in some of which strain is localized in the form of shear bands and necks. These deformations are modeled with partial success, though adiabatic heating of the instability causes inaccuracies for this isothermal implementation of the model. The plastic mechanism has advantages over the Eyring process, is equally tractable, and presents no particular difficulties in implementation with finite elements.

Application of activated barrier hopping theory to viscoplastic modeling of glassy polymers

NASA Astrophysics Data System (ADS)

Sweeney, J.; Spencer, P. E.; Vgenopoulos, D.; Babenko, M.; Boutenel, F.; Caton-Rose, P.; Coates, P. D.

2017-10-01

An established statistical mechanical theory of amorphous polymer deformation has been incorporated as a plastic mechanism into a constitutive model and applied to a range of polymer mechanical deformations. The temperature and rate dependence of the tensile yield of PVC, as reported in early studies, has been modeled to high levels of accuracy. Tensile experiments on PET reported here are analyzed similarly and good accuracy is also achieved. The frequently observed increase in the gradient of the plot of yield stress against logarithm of strain rate is an inherent feature of the constitutive model. The form of temperature dependence of the yield that is predicted by the model is found to give an accurate representation. The constitutive model is developed in two-dimensional form and implemented as a user-defined subroutine in the finite element package ABAQUS. This analysis is applied to the tensile experiments on PET, in some of which strain is localized in the form of shear bands and necks. These deformations are modeled with partial success, though adiabatic heating of the instability causes inaccuracies for this isothermal implementation of the model. The plastic mechanism has advantages over the Eyring process, is equally tractable, and presents no particular difficulties in implementation with finite elements.

Confined dynamics of grafted polymer chains in solutions of linear polymer

DOE PAGES

Poling-Skutvik, Ryan D.; Olafson, Katy N.; Narayanan, Suresh; ...

2017-09-11

Here, we measure the dynamics of high molecular weight polystyrene grafted to silica nanoparticles dispersed in semidilute solutions of linear polymer. Structurally, the linear free chains do not penetrate the grafted corona but increase the osmotic pressure of the solution, collapsing the grafted polymer and leading to eventual aggregation of the grafted particles at high matrix concentrations. Dynamically, the relaxations of the grafted polymer are controlled by the solvent viscosity according to the Zimm model on short time scales. On longer time scales, the grafted chains are confined by neighboring grafted chains, preventing full relaxation over the experimental time scale.more » Adding free linear polymer to the solution does not affect the initial Zimm relaxations of the grafted polymer but does increase the confinement of the grafted chains. Finally, our results elucidate the physics underlying the slow relaxations of grafted polymer.« less

Confined dynamics of grafted polymer chains in solutions of linear polymer

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

Poling-Skutvik, Ryan D.; Olafson, Katy N.; Narayanan, Suresh

Here, we measure the dynamics of high molecular weight polystyrene grafted to silica nanoparticles dispersed in semidilute solutions of linear polymer. Structurally, the linear free chains do not penetrate the grafted corona but increase the osmotic pressure of the solution, collapsing the grafted polymer and leading to eventual aggregation of the grafted particles at high matrix concentrations. Dynamically, the relaxations of the grafted polymer are controlled by the solvent viscosity according to the Zimm model on short time scales. On longer time scales, the grafted chains are confined by neighboring grafted chains, preventing full relaxation over the experimental time scale.more » Adding free linear polymer to the solution does not affect the initial Zimm relaxations of the grafted polymer but does increase the confinement of the grafted chains. Finally, our results elucidate the physics underlying the slow relaxations of grafted polymer.« less

Co-biodegradation of anthracene and naphthalene by the bacterium Acinetobacter johnsonii.

PubMed

Jiang, Yan; Qi, Hui; Zhang, Xian M

2018-04-16

NAP (Naphthalene) and ANT (anthracene) usually co-exist in environment and possessed interactional effects on their biodegradation in environment. Presently, a strain of Acinetobacter johnsonii was employed to degrade NAP and ANT in single- and dual-substrate systems. NAP was utilized as prefer substrate by cells to accelerate ANT biodegradation. As much as 200 mg L -1 ANT could be entirely degraded with 1,500 mg L -1 NAP, which was beyond bacterial potential in single substrate system. Especially, the shortest biodegradation period (103 h) for ANT was observed with the presence of 50 mg L -1 NAP. By contrast, ANT showed strong inhibition on NAP degradation, while the peak biodegradation of 1,950 mg L -1 NAP with 50 mg L -1 ANT could still proceed. By introducing an inhibition constant parameter to fit the inhibition on cells, modeling indicated the substrate inhibition for NAP and ANT over the concentrations of 174 and 49 mg L -1 , respectively. Furthermore, enzyme assay revealed the pathway of meta fission in NAP biodegradation due to the appearance of catechol 2,3-dioxygenase activity, and low-level lipase excretion was also found in both NAP and ANT biodegradation, but hardly affect NAP and ANT biodegradation in the present study. To research the interplay of NAP and ANT is conducive to targeted decontamination.

The dose-response decrease in heart rate variability: any association with the metabolites of polycyclic aromatic hydrocarbons in coke oven workers?

PubMed

Li, Xiaohai; Feng, Yingying; Deng, Huaxin; Zhang, Wangzhen; Kuang, Dan; Deng, Qifei; Dai, Xiayun; Lin, Dafeng; Huang, Suli; Xin, Lili; He, Yunfeng; Huang, Kun; He, Meian; Guo, Huan; Zhang, Xiaomin; Wu, Tangchun

2012-01-01

Air pollution has been associated with an increased risk of cardiopulmonary mortality and decreased heart rate variability (HRV). However, it is unclear whether coke oven emissions (COEs) and polycyclic aromatic hydrocarbons (PAHs) are associated with HRV. Our goal in the present study was to investigate the association of exposure to COEs and the urinary metabolite profiles of PAHs with HRV of coke oven workers. We measured benzene soluble matter, carbon monoxide, sulfur dioxide, particulate matters, and PAHs at different workplaces of a coke oven plant. We determined 10 urinary PAH metabolites and HRV indices of 1333 workers using gas chromatography-mass spectrometry and a 3-channel digital Holter monitor, respectively. Our results showed that there was a significant COEs-related dose-dependent decrease in HRV, and an inverse relationship between the quartiles of urinary 2-hydroxynaphthalene and five HRV indices (p(trend)<0.01 for all). After adjustment for potential confounders, elevation per interquartile range (IQR) (1.81 µg/mmol creatinine) of urinary 2-hydroxynaphthalene was associated with a 5.46% (95% CI, 2.50-8.32) decrease in standard deviation of NN intervals (SDNN). As workers worked more years, SDNN gradually declined in the same quartiles of 2-hydroxynaphthalene levels (p(trend) = 1.40×10(-4)), especially in workers with the highest levels of 2-hydroxynaphthalene. Occupational exposure to COEs is associated with a dose-response decrease in HRV. In particular, increased exposure to 2-hydroxynaphthalene is associated with significantly decreased HRV. Increase of working years and exposure levels has resulted in a gradual decline of HRV.

Effect of phytoremediation on concentrations of benzene, toluene, naphthalene, and dissolved oxygen in groundwater at a former manufactured gas plant site, Charleston, South Carolina, USA, 1998–2014

USGS Publications Warehouse

Landmeyer, James E.; Effinger, Thomas N.

2016-01-01

Concentrations of benzene, toluene, naphthalene, and dissolved oxygen in groundwater at a former manufactured gas plant site near Charleston, South Carolina, USA, have been monitored since the installation of a phytoremediation system of hybrid poplar trees in 1998. Between 2000 and 2014, the concentrations of benzene, toluene, and naphthalene (BT&N) in groundwater in the planted area have decreased. For example, in the monitoring well containing the highest concentrations of BT&N, benzene concentrations decreased from 10,200 µg/L to less than 4000 µg/L, toluene concentrations decreased from 2420 µg/L to less than 20 µg/L, and naphthalene concentrations decreased from 6840 µg/L to less than 3000 µg/L. Concentrations of BT&N in groundwater in all wells were observed to be lower during the summer months relative to the winter months of a particular year during the first few years after installing the phytoremediation system, most likely due to increased transpiration and contaminant uptake by the hybrid poplar trees during the warm summer months; this pathway of uptake by trees was confirmed by the detection of benzene, toluene, and naphthalene in trees during sampling events in 2002, and later in the study in 2012. These data suggest that the phytoremediation system affects the groundwater contaminants on a seasonal basis and, over multiple years, has resulted in a cumulative decrease in dissolved-phase contaminant concentrations in groundwater. The removal of dissolved organic contaminants from the aquifer has resulted in a lower demand on dissolved oxygen supplied by recharge and, as a result, the redox status of the groundwater has changed from anoxic to oxic conditions. This study provides much needed information for water managers and other scientists on the viability of the long-term effectiveness of phytoremediation in decreasing groundwater contaminants and increasing dissolved oxygen at sites contaminated by benzene, toluene, and naphthalene.

Simulating the flow of entangled polymers.

PubMed

Masubuchi, Yuichi

2014-01-01

To optimize automation for polymer processing, attempts have been made to simulate the flow of entangled polymers. In industry, fluid dynamics simulations with phenomenological constitutive equations have been practically established. However, to account for molecular characteristics, a method to obtain the constitutive relationship from the molecular structure is required. Molecular dynamics simulations with atomic description are not practical for this purpose; accordingly, coarse-grained models with reduced degrees of freedom have been developed. Although the modeling of entanglement is still a challenge, mesoscopic models with a priori settings to reproduce entangled polymer dynamics, such as tube models, have achieved remarkable success. To use the mesoscopic models as staging posts between atomistic and fluid dynamics simulations, studies have been undertaken to establish links from the coarse-grained model to the atomistic and macroscopic simulations. Consequently, integrated simulations from materials chemistry to predict the macroscopic flow in polymer processing are forthcoming.

Multi-scale modeling of diffusion-controlled reactions in polymers: renormalisation of reactivity parameters.

PubMed

Everaers, Ralf; Rosa, Angelo

2012-01-07

The quantitative description of polymeric systems requires hierarchical modeling schemes, which bridge the gap between the atomic scale, relevant to chemical or biomolecular reactions, and the macromolecular scale, where the longest relaxation modes occur. Here, we use the formalism for diffusion-controlled reactions in polymers developed by Wilemski, Fixman, and Doi to discuss the renormalisation of the reactivity parameters in polymer models with varying spatial resolution. In particular, we show that the adjustments are independent of chain length. As a consequence, it is possible to match reactions times between descriptions with different resolution for relatively short reference chains and to use the coarse-grained model to make quantitative predictions for longer chains. We illustrate our results by a detailed discussion of the classical problem of chain cyclization in the Rouse model, which offers the simplest example of a multi-scale descriptions, if we consider differently discretized Rouse models for the same physical system. Moreover, we are able to explore different combinations of compact and non-compact diffusion in the local and large-scale dynamics by varying the embedding dimension.

Modeling pressure-driven assembly of polymer coated nanoparticles

NASA Astrophysics Data System (ADS)

Lane, J. Matthew D.; Salerno, K. Michael; Grest, Gary S.; Fan, Hongyou

2017-06-01

High-pressure experiments have successfully produced a variety of gold nanostructures by compressing polymer coated spherical nanoparticles. We apply atomistic simulation to understand the role of the soft polymer response in determining the pressure-driven assembly of gold nanostructures. Quasi-isentropic experiments have shown that 1D, 2D and 3D nanostructures can be formed and recovered from dynamic compression of fcc superlattices of alkanethiol-coated gold nanocrystals on Sandia's Veloce pulsed power accelerator. Molecular modeling has shown that the dimensionality of the final structures depends on the orientation of the superlattice and the uniaxial loading. We describe the role of coating ligand length and grafting density, on ligand migration and deformation processes during pressure-driven coalescence of the cores into permanent nanowires, nanosheets and 3D structures. The role of uniaxial vs isotropic pressure and the effects of compression along various superlattice orientations will be discussed. Sandia National Laboratories is a multi-mission laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Modeling Woven Polymer Matrix Composites with MAC/GMC

NASA Technical Reports Server (NTRS)

Bednarcyk, Brett A.; Arnold, Steven M. (Technical Monitor)

2000-01-01

NASA's Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC) is used to predict the elastic properties of plain weave polymer matrix composites (PMCs). The traditional one step three-dimensional homogertization procedure that has been used in conjunction with MAC/GMC for modeling woven composites in the past is inaccurate due to the lack of shear coupling inherent to the model. However, by performing a two step homogenization procedure in which the woven composite repeating unit cell is homogenized independently in the through-thickness direction prior to homogenization in the plane of the weave, MAC/GMC can now accurately model woven PMCs. This two step procedure is outlined and implemented, and predictions are compared with results from the traditional one step approach and other models and experiments from the literature. Full coupling of this two step technique with MAC/ GMC will result in a widely applicable, efficient, and accurate tool for the design and analysis of woven composite materials and structures.

Heterogeneous nucleation of polymorphs on polymer surfaces: polymer-molecule interactions using a Coulomb and van der Waals model.

PubMed

Wahlberg, Nanna; Madsen, Anders Ø; Mikkelsen, Kurt V

2018-06-09

The nucleation processes of acetaminophen on poly(methyl methacrylate) and poly(vinyl acetate) have been investigated and the mechanisms of the processes are studied. This is achieved by a combination of theoretical models and computational investigations within the framework of a modified QM/MM method; a Coulomb-van der Waals model. We have combined quantum mechanical computations and electrostatic models at the atomistic level for investigating the stability of different orientations of acetaminophen on the polymer surfaces. Based on the Coulomb-van der Waals model, we have determined the most stable orientation to be a flat orientation, and the strongest interaction is seen between poly(vinyl acetate) and the molecule in a flat orientation in vacuum.

Modeling and prediction of relaxation of polar order in high-activity nonlinear optical polymers

NASA Astrophysics Data System (ADS)

Guenthner, Andrew J.; Lindsay, Geoffrey A.; Wright, Michael E.; Fallis, Stephen; Ashley, Paul R.; Sanghadasa, Mohan

2007-09-01

Mach-Zehnder optical modulators were fabricated using the CLD and FTC chromophores in polymer-on-silicon optical waveguides. Up to 17 months of oven-ageing stability are reported for the poled polymer films. Modulators containing an FTC-polyimide had the best over all aging performance. To model and extrapolate the ageing data, a relaxation correlation function attributed to A. K. Jonscher was compared to the well-established stretched exponential correlation function. Both models gave a good fit to the data. The Jonscher model predicted a slower relaxation rate in the out years. Analysis showed that collecting data for a longer period relative to the relaxation time was more important for generating useful predictions than the precision with which individual model parameters could be estimated. Thus from a practical standpoint, time-temperature superposition must be assumed in order to generate meaningful predictions. For this purpose, Arrhenius-type expressions were found to relate the model time constants to the ageing temperatures.

Polymer-coated compliant receivers for intact laser-induced forward transfer of thin films: experimental results and modelling

NASA Astrophysics Data System (ADS)

Feinaeugle, Matthias; Horak, Peter; Sones, Collin L.; Lippert, Thomas; Eason, Rob W.

2014-09-01

In this study, we investigate both experimentally and numerically laser-induced forward transfer (LIFT) of thin films to determine the role of a thin polymer layer coating the receiver with the aim of modifying the rate of deceleration and reduction of material stress preventing intact material transfer. A numerical model of the impact phase during LIFT shows that such a layer reduces the modelled stress. The evolution of stress within the transferred deposit and the substrate as a function of the thickness of the polymer layer, the transfer velocity and the elastic properties of the polymer are evaluated. The functionality of the polymer layer is verified experimentally by LIFT printing intact 1- m-thick bismuth telluride films and polymeric light-emitting diode pads onto a layer of 12-m-thick polydimethylsiloxane and 50-nm-thick poly(3,4-ethylenedioxythiophene) blended with poly(styrenesulfonate) (PEDOT:PSS), respectively. Furthermore, it is demonstrated experimentally that the introduction of such a compliant layer improves adhesion between the deposit and its substrate.

Modelling drug degradation in a spray dried polymer dispersion using a modified Arrhenius equation.

PubMed

Patterson, Adele; Ferreira, Ana P; Banks, Elizabeth; Skeene, Kirsty; Clarke, Graham; Nicholson, Sarah; Rawlinson-Malone, Clare

2015-01-15

The Pharmaceutical industry is increasingly utilizing amorphous technologies to overcome solubility challenges. A common approach is the use of drug in polymer dispersions to prevent recrystallization of the amorphous drug. Understanding the factors affecting chemical and physical degradation of the drug within these complex systems, e.g., temperature and relative humidity, is an important step in the selection of a lead formulation, and development of appropriate packaging/storage control strategies. The Arrhenius equation has been used as the basis of a number of models to predict the chemical stability of formulated product. In this work, we investigate the increase in chemical degradation seen for one particular spray dried dispersion formulation using hydroxypropyl methylcellulose acetate succinate (HPMC-AS). Samples, prepared using polymers with different substitution levels, were placed on storage for 6 months under a range of different temperature and relative humidity conditions and the degradant level monitored using high-performance liquid chromatography (HPLC). While the data clearly illustrates the impact of temperature and relative humidity on the degradant levels detected, it also highlighted that these terms do not account for all the variability in the data. An extension of the Arrhenius equation to include a term for the polymer chemistry, specifically the degree of succinoyl substitution on the polymer backbone, was shown to improve the fit of the model to the data. Copyright © 2014 Elsevier B.V. All rights reserved.

Modeling of fixed-bed column studies for the adsorption of cadmium onto novel polymer-clay composite adsorbent.

PubMed

Unuabonah, Emmanuel I; Olu-Owolabi, Bamidele I; Fasuyi, Esther I; Adebowale, Kayode O

2010-07-15

Kaolinite clay was treated with polyvinyl alcohol to produce a novel water-stable composite called polymer-clay composite adsorbent. The modified adsorbent was found to have a maximum adsorption capacity of 20,400+/-13 mg/L (1236 mg/g) and a maximum adsorption rate constant of approximately = 7.45x10(-3)+/-0.0002 L/(min mg) at 50% breakthrough. Increase in bed height increased both the breakpoint and exhaustion point of the polymer-clay composite adsorbent. The time for the movement of the Mass Transfer Zone (delta) down the column was found to increase with increasing bed height. The presence of preadsorbed electrolyte and regeneration were found to reduce this time. Increased initial Cd(2+) concentration, presence of preadsorbed electrolyte, and regeneration of polymer-clay composite adsorbent reduced the volume of effluent treated. Premodification of polymer-clay composite adsorbent with Ca- and Na-electrolytes reduced the rate of adsorption of Cd(2+) onto polymer-clay composite and lowered the breakthrough time of the adsorbent. Regeneration and re-adsorption studies on the polymer-clay composite adsorbent presented a decrease in the bed volume treated at both the breakpoint and exhaustion points of the regenerated bed. Experimental data were observed to show stronger fits to the Bed Depth Service Time (BDST) model than the Thomas model. 2010 Elsevier B.V. All rights reserved.

Statistics of polymer extensions in turbulent channel flow.

PubMed

Bagheri, Faranggis; Mitra, Dhrubaditya; Perlekar, Prasad; Brandt, Luca

2012-11-01

We present direct numerical simulations of turbulent channel flow with passive Lagrangian polymers. To understand the polymer behavior we investigate the behavior of infinitesimal line elements and calculate the probability distribution function (PDF) of finite-time Lyapunov exponents and from them the corresponding Cramer's function for the channel flow. We study the statistics of polymer elongation for both the Oldroyd-B model (for Weissenberg number Wi<1) and the FENE model. We use the location of the minima of the Cramer's function to define the Weissenberg number precisely such that we observe coil-stretch transition at Wi ≈1. We find agreement with earlier analytical predictions for PDF of polymer extensions made by Balkovsky, Fouxon, and Lebedev [Phys. Rev. Lett. 84, 4765 (2000)] for linear polymers (Oldroyd-B model) with Wi <1 and by Chertkov [Phys. Rev. Lett. 84, 4761 (2000)] for nonlinear FENE-P model of polymers. For Wi >1 (FENE model) the polymer are significantly more stretched near the wall than at the center of the channel where the flow is closer to homogenous isotropic turbulence. Furthermore near the wall the polymers show a strong tendency to orient along the streamwise direction of the flow, but near the center line the statistics of orientation of the polymers is consistent with analogous results obtained recently in homogeneous and isotropic flows.

Recycle polymer characterization and adhesion modeling

NASA Astrophysics Data System (ADS)

Holbery, James David

Contaminants from paper product producers that adversely affect fiber yield have been collected from mills located in three North American geographic regions. Samples have been fractionated using a modified solvent extraction process and subsequently quantitatively characterized and it was found that agglomerates were comprised of the following: approximately 30% extractable polymeric material, 25--35% fiber, 12--15% inorganic material, 15% non-extractable high molecular-weight polyethylene or cross-linked polymers, and 2--4% starch residue. Three representative polymers, paraffin, low-molecular weight polyethylene, and a commercial hot-melt adhesive were selected for further analysis to model the attractive and repulsive behavior using Scanning Probe Microscopy in an aqueous cell. Scanning force probes were characterized using an original technique utilizing a nano-indentation apparatus that is non-destructive and is accurate to within 10% for probes with force constants as low as 1 N/m. Surface force measurements were performed between a Poly (Styrene/30% Butyl Methacrylate) sphere and substrates produced from paraffin, polyethylene, and a commercial hot-melt adhesive in solutions ranging in NaF ionic concentrations from 0.001M to 1M. Reasonable theoretical agreement with experimental data has been shown between a combined model applying van der Waals force contributions using the Derjaguin approximation and electrostatic contributions as predicted by a Debye-Huckel linearization of the Poisson-Boltzmann equation utilizing Hamaker constants derived from critical surface energies determined from Zisman and Lifshitz-van der Waals energy approaches. This model has been applied to measured data and indicates the strength of adhesion for the hot-melt to be 0.14 nN while that of paraffin is 1.9 nN and polyethylene 2.8 nN. Paraffin and polyethylene are 13.5 and 20 times greater in attraction than the hot-melt adhesive. Hot-melt adhesive repulsion is predicted to be 220

Time-dependent deformation of polymer network in polymer-stabilized cholesteric liquid crystals (Conference Presentation)

NASA Astrophysics Data System (ADS)

Lee, Kyung Min; Tondiglia, Vincent P.; Bunning, Timothy J.; White, Timothy J.

2017-02-01

Recently, we reported direct current (DC) field controllable electro-optic (EO) responses of negative dielectric anisotropy polymer stabilized cholesteric liquid crystals (PSCLCs). A potential mechanism is: Ions in the liquid crystal mixtures are trapped in/on the polymer network during the fast photopolymerization process, and the movement of ions by the application of the DC field distorts polymer network toward the negative electrode, inducing pitch variation through the cell thickness, i.e., pitch compression on the negative electrode side and pitch expansion on positive electrode side. As the DC voltage is directly applied to a target voltage, charged polymer network is deformed and the reflection band is tuned. Interestingly, the polymer network deforms further (red shift of reflection band) with time when constantly applied DC voltage, illustrating DC field induced time dependent deformation of polymer network (creep-like behavior). This time dependent reflection band changes in PSCLCs are investigated by varying the several factors, such as type and concentration of photoinitiators, liquid crystal monomer content, and curing condition (UV intensity and curing time). In addition, simple linear viscoelastic spring-dashpot models, such as 2-parameter Kelvin and 3-parameter linear models, are used to investigate the time-dependent viscoelastic behaviors of polymer networks in PSCLC.

Reduction of benzene and naphthalene mass transfer from crude oils by aging-induced interfacial films.

PubMed

Ghoshal, Subhasis; Pasion, Catherine; Alshafie, Mohammed

2004-04-01

Semi-rigid films or skins form at the interface of crude oil and water as a result of the accumulation of asphaltene and resin fractions when the water-immiscible crude oil is contacted with water for a period of time or "aged". The time varying patterns of area-independent mass transfer coefficients of two compounds, benzene and naphthalene, for dissolution from crude oil and gasoline were determined. Aqueous concentrations of the compounds were measured in the eluent from flow-through reactors, where a nondispersed oil phase and constant oil-water interfacial area were maintained. For Brent Blend crude oil and for gasoline amended with asphaltenes and resins, a rapid decrease in both benzene and naphthalene mass transfer coefficients over the first few days of aging was observed. The mass transfer coefficients of the two target solutes were reduced by up to 80% over 35 d although the equilibrium partition coefficients were unchanged. Aging of gasoline, which has negligible amounts of asphaltene and resin, did not result in a change in the solute mass transfer coefficients. The study demonstrates that formation of crude oil-water interfacial films comprised of asphaltenes and resins contribute to time-dependent decreases in rates of release of environmentally relevant solutes from crude oils and may contribute to the persistence of such solutes at crude oil-contaminated sites. It is estimated that the interfacial film has an extremely low film mass transfer coefficient in the range of 10(-6) cm/min.

Assessment of different polymers and drug loads for fused deposition modeling of drug loaded implants.

PubMed

Kempin, Wiebke; Franz, Christian; Koster, Lynn-Christine; Schneider, Felix; Bogdahn, Malte; Weitschies, Werner; Seidlitz, Anne

2017-06-01

The 3D printing technique of fused deposition modeling® (FDM) has lately come into focus as a potential fabrication technique for pharmaceutical dosage forms and medical devices that allows the preparation of delivery systems with nearly any shape. This is particular promising for implants administered at application sites with a high anatomical variability where an individual shape adaption appears reasonable. In this work different polymers (Eudragit®RS, polycaprolactone (PCL), poly(l-lactide) (PLLA) and ethyl cellulose (EC)) were evaluated with respect to their suitability for FDM of drug loaded implants and their drug release behaviour was evaluated. The fluorescent dye quinine was used as a model drug to visualize drug distribution in filaments and implants. Quinine loaded filaments were produced by solvent casting and subsequent hot melt extrusion (HME) and model implants were printed as hollow cylinders using a standard FDM printer. Parameters were found at which model implants (hollow cylinders, outer diameter 4-5mm, height 3mm) could be produced from all tested polymers. The drug release which was examined by incubation of the printed implants in phosphate buffered saline solution (PBS) pH 7.4 was highly dependent on the used polymer. The fastest relative drug release of approximately 76% in 51days was observed for PCL and the lowest for Eudragit®RS and EC with less than 5% of quinine release in 78 and 100days, respectively. For PCL further filaments were prepared with different quinine loads ranging from 2.5% to 25% and thermal analysis proved the presence of a solid dispersion of quinine in the polymer for all tested concentrations. Increasing the drug load also increased the overall percentage of drug released to the medium since nearly the same absolute amount of quinine remained trapped in PCL at the end of drug release studies. This knowledge is valuable for future developments of printed implants with a desired drug release profile that might be

Accelerated Discovery of High-Refractive-Index Polymers Using First-Principles Modeling, Virtual High-Throughput Screening, and Data Mining

NASA Astrophysics Data System (ADS)

Afzal, Mohammad Atif Faiz; Cheng, Chong; Hachmann, Johannes

Organic materials with refractive index (RI) values higher than 1.7 have attracted considerable interest in recent years due to the tremendous potential for their application in optical, optometric, and optoelectronic devices, and thus for shaping technological innovation in numerous related areas. Our work is concerned with creating predictive models for the optical properties of organic polymers, which will guide our experimentalist partners and allow them to target the most promising candidates. The RI model is developed based on a synergistic combination of first-principles electronic structure theory and machine learning techniques. The RI values predicted for common polymers using this model are in very good agreement with the experimental values. We also benchmark different DFT approximations along with various basis sets for their predictive performance in this model. We demonstrate that this combination of first-principles and data modeling is both successful and highly economical in determining the RI values of a wide range of organic polymers. To accelerate the development process, we cast this modeling approach into the high-throughput screening, materials informatics, and rational design framework that is developed in the group. This framework is a powerful tool and has shown to be highly promising for rapidly identifying polymer candidates with exceptional RI values as well as discovering design rules for advanced materials.

Monte Carlo Computational Modeling of the Energy Dependence of Atomic Oxygen Undercutting of Protected Polymers

NASA Technical Reports Server (NTRS)

Banks, Bruce A.; Stueber, Thomas J.; Norris, Mary Jo

1998-01-01

A Monte Carlo computational model has been developed which simulates atomic oxygen attack of protected polymers at defect sites in the protective coatings. The parameters defining how atomic oxygen interacts with polymers and protective coatings as well as the scattering processes which occur have been optimized to replicate experimental results observed from protected polyimide Kapton on the Long Duration Exposure Facility (LDEF) mission. Computational prediction of atomic oxygen undercutting at defect sites in protective coatings for various arrival energies was investigated. The atomic oxygen undercutting energy dependence predictions enable one to predict mass loss that would occur in low Earth orbit, based on lower energy ground laboratory atomic oxygen beam systems. Results of computational model prediction of undercut cavity size as a function of energy and defect size will be presented to provide insight into expected in-space mass loss of protected polymers with protective coating defects based on lower energy ground laboratory testing.

Diketopyrrolopyrrole-based polymer:fullerene nanoparticle films with thermally stable morphology for organic photovoltaic applications

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

Holmes, Natalie P.; Vaughan, Ben; Williams, Evan L.

Polymer:fullerene nanoparticles (NPs) offer two key advantages over bulk heterojunction (BHJ) films for organic photovoltaics (OPVs), water-processability and potentially superior morphological control. Once an optimal active layer morphology is reached, maintaining this morphology at OPV operating temperatures is key to the lifetime of a device. Here in this paper we study the morphology of the PDPP-TNT (poly{3,6-dithiophene-2-yl-2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]pyrrole-1,4-dione-alt-naphthalene}):PC 71BM ([6,6]-phenyl C 71 butyric acid methyl ester) NP system and then compare the thermal stability of NP and BHJ films to the common poly(3-hexylthiophene) (P3HT): phenyl C 61 butyric acid methyl ester (PC 61BM) system. We find that material T g playsmore » a key role in the superior thermal stability of the PDPP-TNT:PC 71BM system; whereas for the P3HT:PC 61BM system, domain structure is critical.« less

Temperature modeling of laser-irradiated azo-polymer thin films.

PubMed

Yager, Kevin G; Barrett, Christopher J

2004-01-08

Azobenzene polymer thin films exhibit reversible surface mass transport when irradiated with a light intensity and/or polarization gradient, although the exact mechanism remains unknown. In order to address the role of thermal effects in the surface relief grating formation process peculiar to azo polymers, a cellular automaton simulation was developed to model heat flow in thin films undergoing laser irradiation. Typical irradiation intensities of 50 mW/cm2 resulted in film temperature rises on the order of 5 K, confirmed experimentally. The temperature gradient between the light maxima and minima was found, however, to stabilize at only 10(-4) K within 2 micros. These results indicate that thermal effects play a negligible role during inscription, for films of any thickness. Experiments monitoring surface relief grating formation on substrates of different thermal conductivity confirm that inscription is insensitive to film temperature. Further simulations suggest that high-intensity pulsed irradiation leads to destructive temperatures and sample ablation, not to reversible optical mass transport. (c) 2004 American Institute of Physics

Effect of matrix chemical heterogeneity on effective filler interactions in model polymer nanocomposites

NASA Astrophysics Data System (ADS)

Hall, Lisa; Schweizer, Kenneth

2010-03-01

The microscopic Polymer Reference Interaction Site Model theory has been applied to spherical and rodlike fillers dissolved in three types of chemically heterogeneous polymer melts: alternating AB copolymer, random AB copolymers, and an equimolar blend of two homopolymers. In each case, one monomer species adsorbs more strongly on the filler mimicking a specific attraction, while all inter-monomer potentials are hard core which precludes macrophase or microphase separation. Qualitative differences in the filler potential-of-mean force are predicted relative to the homopolymer case. The adsorbed bound layer for alternating copolymers exhibits a spatial moduluation or layering effect but is otherwise similar to that of the homopolymer system. Random copolymers and the polymer blend mediate a novel strong, long-range bridging interaction between fillers at moderate to high adsorption strengths. The bridging strength is a non-monotonic function of random copolymer composition, reflecting subtle competing enthalpic and entropic considerations.

Phase behavior of ternary polymer brushes

DOE PAGES

Simocko, Chester K.; Frischknecht, Amalie L.; Huber, Dale L.

2016-01-07

Ternary polymer brushes consisting of polystyrene, poly(methyl methacrylate), and poly(4-vinylpyridine) have been synthesized. These brushes laterally phase separate into several distinct phases and can be tailored by altering the relative polymer composition. Self-consistent field theory has been used to predict the phase diagram and model both the horizontal and vertical phase behavior of the polymer brushes. As a result, all phase behaviors observed experimentally correlate well with the theoretical model.

Communication: Polarizable polymer chain under external electric field in a dilute polymer solution.

PubMed

Budkov, Yu A; Kolesnikov, A L; Kiselev, M G

2015-11-28

We study the conformational behavior of polarizable polymer chain under an external homogeneous electric field within the Flory type self-consistent field theory. We consider the influence of electric field on the polymer coil as well as on the polymer globule. We show that when the polymer chain conformation is a coil, application of external electric field leads to its additional swelling. However, when the polymer conformation is a globule, a sufficiently strong field can induce a globule-coil transition. We show that such "field-induced" globule-coil transition at the sufficiently small monomer polarizabilities goes quite smoothly. On the contrary, when the monomer polarizability exceeds a certain threshold value, the globule-coil transition occurs as a dramatic expansion in the regime of first-order phase transition. The developed theoretical model can be applied to predicting polymer globule density change under external electric field in order to provide more efficient processes of polymer functionalization, such as sorption, dyeing, and chemical modification.

A single particle model to simulate the dynamics of entangled polymer melts.

PubMed

Kindt, P; Briels, W J

2007-10-07

We present a computer simulation model of polymer melts representing each chain as one single particle. Besides the position coordinate of each particle, we introduce a parameter n(ij) for each pair of particles i and j within a specified distance from each other. These numbers, called entanglement numbers, describe the deviation of the system of ignored coordinates from its equilibrium state for the given configuration of the centers of mass of the polymers. The deviations of the entanglement numbers from their equilibrium values give rise to transient forces, which, together with the conservative forces derived from the potential of mean force, govern the displacements of the particles. We have applied our model to a melt of C(800)H(1602) chains at 450 K and have found good agreement with experiments and more detailed simulations. Properties addressed in this paper are radial distribution functions, dynamic structure factors, and linear as well as nonlinear rheological properties.

Elucidating fluctuating diffusivity in center-of-mass motion of polymer models with time-averaged mean-square-displacement tensor

NASA Astrophysics Data System (ADS)

Miyaguchi, Tomoshige

2017-10-01

There have been increasing reports that the diffusion coefficient of macromolecules depends on time and fluctuates randomly. Here a method is developed to elucidate this fluctuating diffusivity from trajectory data. Time-averaged mean-square displacement (MSD), a common tool in single-particle-tracking (SPT) experiments, is generalized to a second-order tensor with which both magnitude and orientation fluctuations of the diffusivity can be clearly detected. This method is used to analyze the center-of-mass motion of four fundamental polymer models: the Rouse model, the Zimm model, a reptation model, and a rigid rodlike polymer. It is found that these models exhibit distinctly different types of magnitude and orientation fluctuations of diffusivity. This is an advantage of the present method over previous ones, such as the ergodicity-breaking parameter and a non-Gaussian parameter, because with either of these parameters it is difficult to distinguish the dynamics of the four polymer models. Also, the present method of a time-averaged MSD tensor could be used to analyze trajectory data obtained in SPT experiments.

Strain Rate Dependent Deformation and Strength Modeling of a Polymer Matrix Composite Utilizing a Micromechanics Approach. Degree awarded by Cincinnati Univ.

NASA Technical Reports Server (NTRS)

Goldberg, Robert K.

1999-01-01

Potential gas turbine applications will expose polymer matrix composites to very high strain rate loading conditions, requiring an ability to understand and predict the material behavior under extreme conditions. Specifically, analytical methods designed for these applications must have the capability of properly capturing the strain rate sensitivities and nonlinearities that are present in the material response. The Ramaswamy-Stouffer constitutive equations, originally developed to analyze the viscoplastic deformation of metals, have been modified to simulate the nonlinear deformation response of ductile, crystalline polymers. The constitutive model is characterized and correlated for two representative ductile polymers. Fiberite 977-2 and PEEK, and the computed results correlate well with experimental values. The polymer constitutive equations are implemented in a mechanics of materials based composite micromechanics model to predict the nonlinear, rate dependent deformation response of a composite ply. Uniform stress and uniform strain assumptions are applied to compute the effective stresses of a composite unit cell from the applied strains. The micromechanics equations are successfully verified for two polymer matrix composites. IM7/977-2 and AS4/PEEK. The ultimate strength of a composite ply is predicted with the Hashin failure criteria that were implemented in the composite micromechanics model. The failure stresses of the two composite material systems are accurately predicted for a variety of fiber orientations and strain rates. The composite deformation model is implemented in LS-DYNA, a commercially available transient dynamic explicit finite element code. The matrix constitutive equations are converted into an incremental form, and the model is implemented into LS-DYNA through the use of a user defined material subroutine. The deformation response of a bulk polymer and a polymer matrix composite are predicted by finite element analyses. The results

The Dose–Response Decrease in Heart Rate Variability: Any Association with the Metabolites of Polycyclic Aromatic Hydrocarbons in Coke Oven Workers?

PubMed Central

Deng, Huaxin; Zhang, Wangzhen; Kuang, Dan; Deng, Qifei; Dai, Xiayun; Lin, Dafeng; Huang, Suli; Xin, Lili; He, Yunfeng; Huang, Kun; He, Meian; Guo, Huan; Zhang, Xiaomin; Wu, Tangchun

2012-01-01

Background Air pollution has been associated with an increased risk of cardiopulmonary mortality and decreased heart rate variability (HRV). However, it is unclear whether coke oven emissions (COEs) and polycyclic aromatic hydrocarbons (PAHs) are associated with HRV. Objectives Our goal in the present study was to investigate the association of exposure to COEs and the urinary metabolite profiles of PAHs with HRV of coke oven workers. Methods We measured benzene soluble matter, carbon monoxide, sulfur dioxide, particulate matters, and PAHs at different workplaces of a coke oven plant. We determined 10 urinary PAH metabolites and HRV indices of 1333 workers using gas chromatography–mass spectrometry and a 3-channel digital Holter monitor, respectively. Results Our results showed that there was a significant COEs-related dose-dependent decrease in HRV, and an inverse relationship between the quartiles of urinary 2-hydroxynaphthalene and five HRV indices (p trend<0.01 for all). After adjustment for potential confounders, elevation per interquartile range (IQR) (1.81 µg/mmol creatinine) of urinary 2-hydroxynaphthalene was associated with a 5.46% (95% CI, 2.50–8.32) decrease in standard deviation of NN intervals (SDNN). As workers worked more years, SDNN gradually declined in the same quartiles of 2-hydroxynaphthalene levels (p trend = 1.40×10−4), especially in workers with the highest levels of 2-hydroxynaphthalene. Conclusions Occupational exposure to COEs is associated with a dose-response decrease in HRV. In particular, increased exposure to 2-hydroxynaphthalene is associated with significantly decreased HRV. Increase of working years and exposure levels has resulted in a gradual decline of HRV. PMID:23024753

Biological monitoring of environmental exposure to polycyclic aromatic hydrocarbons in subjects living in the area of recycling electronic garbage, in Southern China.

PubMed

Wang, Yu; Zhang, Wenbing; Fan, Ruifang; Sheng, Guoying; Fu, Jiamo

2014-01-01

The study was undertaken to evaluate the environmental exposure to polycyclic aromatic hydrocarbons in subjects living in the area of recycling electronic garbage in Southern China and research the influence of environment smoke tobacco (EST) to people through active and passive smoking. Urinary concentrations of 2-hydroxynaphthalene, 2-hydoxyfluorene, 9-hydroxyphenanthrene, and 1-hydroxypyrene were determined in 141 randomly selected voluntary residents aged 13 to 81 years in two polycyclic aromatic hydrocarbon (PAH)-exposed groups, two control groups, and an EST research group. The concentrations of 2-hydroxynaphthalene, 2-hydoxyfluorene, 9-hydroxyphenanthrene, and 1-hydroxypyrene in PAH-exposed groups are significantly higher (p<0.05) than those of control groups. Mean value of 1-hydroxypyrene in the residents living in the area of recycling electronic garbage (1.1 μmol/mol creatinine) is a little higher than those of iron foundry workers, automobile repair workers, and firefighters. Mean value of 2-hydroxynaphthalene (11.3 μmol/mol creatinine) is much higher than that of shipyard and aircraft maintenance and much lower than some occupational exposure, such as coking batteries, sorting department, and distillation department in coking plant. Some metabolites of PAHs (PAHm) are significantly elevated through active and passive smoking, while the influence of EST to other PAHm is not statistically significant. 2-Hydroxynaphthalene, 2-hydoxyfluorene, 9-hydroxyphenanthrene, and 1-hydroxypyrene in the urine of smokers are, respectively, 3.9, 1.9, 1.4, and 1.9 times to those of nonsmokers. In nonsmokers, passive smokers excreted 1.1, 1.5, 1.9, and 1.5 times of 2-hydroxynaphthalene, 2-hydoxyfluorene, 9-hydroxyphenanthrene, and 1-hydroxypyrene compared to nonpassive smokers.

Modeling and Simulation of Ballistic Penetration of Ceramic-Polymer-Metal Layered Systems

DTIC Science & Technology

2016-01-01

ARL-RP-0562 ● JAN 2016 US Army Research Laboratory Modeling and Simulation of Ballistic Penetration of Ceramic-Polymer-Metal...manufacturer’s or trade names does not constitute an official endorsement or approval of the use thereof. Destroy this report when it is no longer needed...Do not return it to the originator. ARL-RP-0562 ● JAN 2016 US Army Research Laboratory Modeling and Simulation of Ballistic

Theoretical approach to the innovative mutation of naphthalene 1,2-dioxygenase: a molecular dynamics and docking study.

PubMed

Librando, Vito; Pappalardo, Matteo

2014-08-01

Polycyclic aromatic hydrocarbons are a family of ubiquitous pollutants whose environmental behavior has been widely studied. Different bacterial species are able to decompose hydrocarbons by using them as a food source. One of the best-studied enzymes is naphthalene 1,2-dioxygenase (NDO). A practical way to optimize the degradation process is by mutating the protein involved, increasing both the degradation capacity of the enzyme and its ability to work under extreme environmental conditions of high temperature and low pH. Herein, we describe the study of NDO using molecular dynamics and docking calculations to discover new mutants with high degrading capabilities. We modeled eleven new mutants of NDO. The results indicate that increasing the size of the active site cavity in the mutants allowed for the insertion of high molecular weight PAHs. Additionally, the physicochemical properties of the NDO active sites make the sites well suited to interactions with PAHs, so most amino-acid modifications should not result in significantly altered behavior of NDO.

Attaching naphthalene derivatives onto BODIPY for generating excited triplet state and singlet oxygen: Tuning PET-based photosensitizer by electron donors

NASA Astrophysics Data System (ADS)

Zhang, Xian-Fu; Feng, Nan

2018-01-01

meso-Naphthalene substituted BODIPY compounds were prepared in a facile one pot reaction. The naphthalene functionalization of BODIPY leads up to a 5-fold increase in the formation efficiency of excited triplet state and singlet oxygen in polar solvents. Steady state and time resolved fluorescence, laser flash photolysis, and quantum chemistry methods were used to reveal the mechanism. All measured data and quantum chemical results suggest that these systems can be viewed as electron donor-acceptor (D-A) pair (BODIPY acts as the acceptor), photoinduced charge transfer (PCT) or photoinduced electron transfer (PET) occurs upon photo excitation (D-A + hν → Dδ +-Aδ -, 0 < δ ≤ 1), and the charge recombination induced the formation of triplet state (Dδ +-Aδ - → D-A (T1). These novel PCT- or PET-based photosensitizers (PSs) show different features from traditional PSs, such as the strong tunability by facile structural modification and good selectivity upon medium polarity. The new character for this type of PSs can lead to important applications in organic oxygenation reactions and photodynamic therapy of tumors.

Lattice model of linear telechelic polymer melts. II. Influence of chain stiffness on basic thermodynamic properties

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

Xu, Wen-Sheng, E-mail: wsxu@uchicago.edu; Freed, Karl F., E-mail: freed@uchicago.edu; Department of Chemistry, The University of Chicago, Chicago, Illinois 60637

2015-07-14

The lattice cluster theory (LCT) for semiflexible linear telechelic melts, developed in Paper I, is applied to examine the influence of chain stiffness on the average degree of self-assembly and the basic thermodynamic properties of linear telechelic polymer melts. Our calculations imply that chain stiffness promotes self-assembly of linear telechelic polymer melts that assemble on cooling when either polymer volume fraction ϕ or temperature T is high, but opposes self-assembly when both ϕ and T are sufficiently low. This allows us to identify a boundary line in the ϕ-T plane that separates two regions of qualitatively different influence of chainmore » stiffness on self-assembly. The enthalpy and entropy of self-assembly are usually treated as adjustable parameters in classical Flory-Huggins type theories for the equilibrium self-assembly of polymers, but they are demonstrated here to strongly depend on chain stiffness. Moreover, illustrative calculations for the dependence of the entropy density of linear telechelic polymer melts on chain stiffness demonstrate the importance of including semiflexibility within the LCT when exploring the nature of glass formation in models of linear telechelic polymer melts.« less

Continuum Model for Decontamination of Chemical Warfare Agent from a Rubbery Polymer using the Maxwell-Stefan Formulation

NASA Astrophysics Data System (ADS)

Varady, Mark; Bringuier, Stefan; Pearl, Thomas; Stevenson, Shawn; Mantooth, Brent

Decontamination of polymers exposed to chemical warfare agents (CWA) often proceeds by application of a liquid solution. Absorption of some decontaminant components proceed concurrently with extraction of the CWA, resulting in multicomponent diffusion in the polymer. In this work, the Maxwell-Stefan equations were used with the Flory-Huggins model of species activity to mathematically describe the transport of two species within a polymer. This model was used to predict the extraction of the nerve agent O-ethyl S-[2(diisopropylamino)ethyl] methylphosphonothioate (VX) from a silicone elastomer into both water and methanol. Comparisons with experimental results show good agreement with minimal fitting of model parameters from pure component uptake data. Reaction of the extracted VX with sodium hydroxide in the liquid-phase was also modeled and used to predict the overall rate of destruction of VX. Although the reaction proceeds more slowly in the methanol-based solution compared to the aqueous solution, the extraction rate is faster due to increasing VX mobility as methanol absorbs into the silicone, resulting in an overall faster rate of VX destruction.

Novel leads from Heliotropium ovalifolium, 4,7,8-trimethoxy-naphthalene-2-carboxylic acid and 6-hydroxy-5,7-dimethoxy-naphthalene-2-carbaldehyde show specific IL-6 inhibitory activity in THP-1 cells and primary human monocytes.

PubMed

Kulkarni-Almeida, Asha; Suthar, Ashish; Goswami, Hitesh; Vishwakarma, Ram; Chauhan, Vijay Singh; Balakrishnan, Arun; Sharma, Somesh

2008-12-01

From our screening program, we identified the anti-inflammatory effects of the extracts of Heliotropium ovalifolium in its ability to inhibit specific cytokines. The H. ovalifolium extract was found to be moderately active with an IC(50) equaling 10 microg/ml for inhibition of interleukin-6 (IL-6) in a human monocytic cell line. Interleukin-6 is a pleiotropic cytokine with implications in the regulation of the immune response, inflammation and hematopoiesis. This prompted us to examine and identify the active molecules that are responsible for the bioactivity in THP-1 cells. Bioassay guided fractionation identified two compounds 4,7,8-trimethoxy-naphthalene-2-carboxylic acid and 6-hydroxy-5,7-dimethoxy-naphthalene-2-carbaldehyde with an IC(50) of 2.4 and 2.0 microM for IL-6 inhibition and an IC(50) of 15.6 and 7.0 microM for tumor necrosis factor-alpha (TNF-alpha) inhibition in THP-1 cells. The protein expression data were supported by the inhibitory effect on mRNA gene expression. The compounds isolated from H. ovalifolium were also non-toxic in human peripheral blood monocytes from normal donors and the activity profile was similar to that obtained on THP-1 cells. Thus, we believe that these scaffolds may be of interest to develop leads for treating rheumatoid arthritis, psoriasis, ulcerative colitis, Crohn's disease and other inflammatory disorders. However, more detailed investigations need to be carried out to explain the efficacy of these compounds as drugs.

On The Geometric Nature of ``Singlet Fission'' in Certain Crystalline Conjugated Polymers

NASA Astrophysics Data System (ADS)

Rahman, Noah

2013-03-01

In recent years, the coherent fission of low-lying singlet electronic excitations in conjugated polymers has attracted interest as a possible way to exceed the Shockley-Queisser limit in organic photovoltaics. Femtosecond spectroscopic and fluorescence measurements of such singlets and the resulting triplets in crystalline anthracene, tetracene and naphthalene reveal curious phenomena associated with certain vibrational modes, such as ultrafast propagation on a timescale inconsistent with conventional intersystem crossing, long-lived electronic coherence, and triplet magnetic anisotropy whose structure is consistent across all three materials. This conflicts with NRG and quantum chemical simulations, which posit isotropic triplets. I explain this by a dynamical Rashba spin-orbit interaction that decays as R-6. This arises from a geometric SU(2) gauge potential generated by a nuclear-motion-induced parametric near-degeneracy of the molecular electronic states. The anisotropy is shown to follow from the work of Affleck and Oshikawa on spin one-half Heisenberg chains. Possible directions for future work are discussed, especially with regard to adiabatic pumping and topological insulators.

Self-assembly and glass-formation in a lattice model of telechelic polymer melts: Influence of stiffness of the sticky bonds

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

Xu, Wen-Sheng, E-mail: wsxu@uchicago.edu; Freed, Karl F., E-mail: freed@uchicago.edu; Department of Chemistry, The University of Chicago, Chicago, Illinois 60637

2016-06-07

Telechelic polymers are chain macromolecules that may self-assemble through the association of their two mono-functional end groups (called “stickers”). A deep understanding of the relation between microscopic molecular details and the macroscopic physical properties of telechelic polymers is important in guiding the rational design of telechelic polymer materials with desired properties. The lattice cluster theory (LCT) for strongly interacting, self-assembling telechelic polymers provides a theoretical tool that enables establishing the connections between important microscopic molecular details of self-assembling polymers and their bulk thermodynamics. The original LCT for self-assembly of telechelic polymers considers a model of fully flexible linear chains [J.more » Dudowicz and K. F. Freed, J. Chem. Phys. 136, 064902 (2012)], while our recent work introduces a significant improvement to the LCT by including a description of chain semiflexibility for the bonds within each individual telechelic chain [W.-S. Xu and K. F. Freed, J. Chem. Phys. 143, 024901 (2015)], but the physically associative (or called “sticky”) bonds between the ends of the telechelics are left as fully flexible. Motivated by the ubiquitous presence of steric constraints on the association of real telechelic polymers that impart an additional degree of bond stiffness (or rigidity), the present paper further extends the LCT to permit the sticky bonds to be semiflexible but to have a stiffness differing from that within each telechelic chain. An analytical expression for the Helmholtz free energy is provided for this model of linear telechelic polymer melts, and illustrative calculations demonstrate the significant influence of the stiffness of the sticky bonds on the self-assembly and thermodynamics of telechelic polymers. A brief discussion is also provided for the impact of self-assembly on glass-formation by combining the LCT description for this extended model of telechelic

Monte Carlo modeling of atomic oxygen attack of polymers with protective coatings on LDEF

NASA Technical Reports Server (NTRS)

Banks, Bruce A.; Degroh, Kim K.; Sechkar, Edward A.

1992-01-01

Characterization of the behavior of atomic oxygen interaction with materials on the Long Duration Exposure Facility (LDEF) will assist in understanding the mechanisms involved, and will lead to improved reliability in predicting in-space durability of materials based on ground laboratory testing. A computational simulation of atomic oxygen interaction with protected polymers was developed using Monte Carlo techniques. Through the use of assumed mechanistic behavior of atomic oxygen and results of both ground laboratory and LDEF data, a predictive Monte Carlo model was developed which simulates the oxidation processes that occur on polymers with applied protective coatings that have defects. The use of high atomic oxygen fluence-directed ram LDEF results has enabled mechanistic implications to be made by adjusting Monte Carlo modeling assumptions to match observed results based on scanning electron microscopy. Modeling assumptions, implications, and predictions are presented, along with comparison of observed ground laboratory and LDEF results.

Use of Molecular Dynamics for the Refinement of an Electrostatic Model for the In Silico Design of a Polymer Antidote for the Anticoagulant Fondaparinux

PubMed Central

Kwok, Ezra; Gopaluni, Bhushan; Kizhakkedathu, Jayachandran N.

2013-01-01

Molecular dynamics (MD) simulations results are herein incorporated into an electrostatic model used to determine the structure of an effective polymer-based antidote to the anticoagulant fondaparinux. In silico data for the polymer or its cationic binding groups has not, up to now, been available, and experimental data on the structure of the polymer-fondaparinux complex is extremely limited. Consequently, the task of optimizing the polymer structure is a daunting challenge. MD simulations provided a means to gain microscopic information on the interactions of the binding groups and fondaparinux that would have otherwise been inaccessible. This was used to refine the electrostatic model and improve the quantitative model predictions of binding affinity. Once refined, the model provided guidelines to improve electrostatic forces between candidate polymers and fondaparinux in order to increase association rate constants. PMID:27006916

Degradation of phenanthrene by Burkholderia sp. C3: initial 1,2- and 3,4-dioxygenation and meta- and ortho-cleavage of naphthalene-1,2-diol.

PubMed

Seo, Jong-Su; Keum, Young-Soo; Hu, Yuting; Lee, Sung-Eun; Li, Qing X

2007-02-01

Burkholderia sp. C3 was isolated from a polycyclic aromatic hydrocarbon (PAH)-contaminated site in Hilo, Hawaii, USA, and studied for its degradation of phenanthrene as a sole carbon source. The initial 3,4-C dioxygenation was faster than 1,2-C dioxygenation in the first 3-day culture. However, 1-hydroxy-2-naphthoic acid derived from 3,4-C dioxygenation degraded much slower than 2-hydroxy-1-naphthoic acid derived from 1,2-C dioxygenation. Slow degradation of 1-hydroxy-2-naphthoic acid relative to 2-hydroxy-1-naphthoic acid may trigger 1,2-C dioxygenation faster after 3 days of culture. High concentrations of 5,6- and 7,8-benzocoumarins indicated that meta-cleavage was the major degradation mechanism of phenanthrene-1,2- and -3,4-diols. Separate cultures with 2-hydroxy-1-naphthoic acid and 1-hydroxy-2-naphthoic acid showed that the degradation rate of the former to naphthalene-1,2-diol was much faster than that of the latter. The two upper metabolic pathways of phenanthrene are converged into naphthalene-1,2-diol that is further metabolized to 2-carboxycinnamic acid and 2-hydroxybenzalpyruvic acid by ortho- and meta-cleavages, respectively. Transformation of naphthalene-1,2-diol to 2-carboxycinnamic acid by this strain represents the first observation of ortho-cleavage of two rings-PAH-diols by a Gram-negative species.

Scattering from Colloid-Polymer Conjugates with Excluded Volume Effect

DOE PAGES

Li, Xin; Sanchez-Diaz, Luis E.; Smith, Gregory Scott; ...

2015-01-13

This work presents scattering functions of conjugates consisting of a colloid particle and a self-avoiding polymer chain as a model for protein-polymer conjugates and nanoparticle-polymer conjugates in solution. The model is directly derived from the two-point correlation function with the inclusion of excluded volume effects. The dependence of the calculated scattering function on the geometric shape of the colloid and polymer stiffness is investigated. The model is able to describe the experimental scattering signature of the solutions of suspending hard particle-polymer conjugates and provide additional conformational information. This model explicitly elucidates the link between the global conformation of a conjugatemore » and the microstructure of its constituent components.« less

Simulation of polymer translocation through protein channels

PubMed Central

Muthukumar, M.; Kong, C. Y.

2006-01-01

A modeling algorithm is presented to compute simultaneously polymer conformations and ionic current, as single polymer molecules undergo translocation through protein channels. The method is based on a combination of Langevin dynamics for coarse-grained models of polymers and the Poisson–Nernst–Planck formalism for ionic current. For the illustrative example of ssDNA passing through the α-hemolysin pore, vivid details of conformational fluctuations of the polymer inside the vestibule and β-barrel compartments of the protein pore, and their consequent effects on the translocation time and extent of blocked ionic current are presented. In addition to yielding insights into several experimentally reported puzzles, our simulations offer experimental strategies to sequence polymers more efficiently. PMID:16567657

Effects of polymer graft properties on protein adsorption and transport in ion exchange chromatography: a multiscale modeling study.

PubMed

Basconi, Joseph E; Carta, Giorgio; Shirts, Michael R

2015-04-14

Multiscale simulation is used to study the adsorption of lysozyme onto ion exchangers obtained by grafting charged polymers into a porous matrix, in systems with various polymer properties and strengths of electrostatic interaction. Molecular dynamics simulations show that protein partitioning into the polymer-filled pore space increases with the overall charge content of the polymers, while the diffusivity in the pore space decreases. However, the combination of greatly increased partitioning and modestly decreased diffusion results in macroscopic transport rates that increase as a function of charge content, as the large concentration driving force due to enhanced pore space partitioning outweighs the reduction in the pore space diffusivity. Matrices having greater charge associated with the grafted polymers also exhibit more diffuse intraparticle concentration profiles during transient adsorption. In systems with a high charge content per polymer and a low protein loading, the polymers preferentially partition toward the surface due to favorable interactions with the surface-bound protein. These results demonstrate the potential of multiscale modeling to illuminate qualitative trends between molecular properties and the adsorption equilibria and kinetic properties observable on macroscopic scales.

Nonlinear dynamics that appears in the dynamical model of drying process of a polymer solution coated on a flat substrate

NASA Astrophysics Data System (ADS)

Kagami, Hiroyuki

2007-01-01

We have proposed and modified the dynamical model of drying process of polymer solution coated on a flat substrate for flat polymer film fabrication and have presented the fruits through some meetings and so on. Though basic equations of the dynamical model have characteristic nonlinearity, character of the nonlinearity has not been studied enough yet. In this paper, at first, we derive nonlinear equations from the dynamical model of drying process of polymer solution. Then we introduce results of numerical simulations of the nonlinear equations and consider roles of various parameters. Some of them are indirectly concerned in strength of non-equilibriumity. Through this study, we approach essential qualities of nonlinearity in non-equilibrium process of drying process.

Structures and Binding Energies of the Naphthalene Dimer in Its Ground and Excited States.

PubMed

Dubinets, N O; Safonov, A A; Bagaturyants, A A

2016-05-05

Possible structures of the naphthalene dimer corresponding to local energy minima in the ground and excited (excimer) electronic states are comprehensively investigated using DFT-D and TDDFT-D methods with a special accent on the excimer structures. The corresponding binding and electronic transition energies are calculated, and the nature of the electronic states in different structures is analyzed. Several parallel (stacked) and T-shaped structures were found in both the ground and excited (excimer) states in a rather narrow energy range. The T-shaped structure with the lowest energy in the excited state exhibits a marked charge transfer from the upright molecule to the base one.

Responsive copolymers for enhanced petroleum recovery. Quarterly technical progress report, June 23--September 21, 1994

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

McCormick, C.; Hester, R.

Summaries are given on the technical progress on three tasks of this project. Monomer and polymer synthesis discusses the preparation of 1(7-aminoheptyloxymethyl)naphthalene and poly(maleic anhydride-alt-ethyl vinyl ether). Task 2, Characterization of molecular structure, discusses terpolymer solution preparation, UV analysis, fluorescence analysis, low angle laser light scattering, and viscometry. The paper discusses the effects of hydrophobic groups, the effect of pH, the effect of electrolyte addition, and photophysical studies. Task 3, Solution properties, describes the factorial experimental design for characterizing polymer solutions by light scattering, the light scattering test model, orthogonal factorial test design, linear regression in coded space, confidence levelmore » for coded space test mode coefficients, coefficients of the real space test model, and surface analysis of the model equations.« less

A constitutive law for degrading bioresorbable polymers.

PubMed

Samami, Hassan; Pan, Jingzhe

2016-06-01

This paper presents a constitutive law that predicts the changes in elastic moduli, Poisson's ratio and ultimate tensile strength of bioresorbable polymers due to biodegradation. During biodegradation, long polymer chains are cleaved by hydrolysis reaction. For semi-crystalline polymers, the chain scissions also lead to crystallisation. Treating each scission as a cavity and each new crystal as a solid inclusion, a degrading semi-crystalline polymer can be modelled as a continuum solid containing randomly distributed cavities and crystal inclusions. The effective elastic properties of a degrading polymer are calculated using existing theories for such solid and the tensile strength of the degrading polymer is predicted using scaling relations that were developed for porous materials. The theoretical model for elastic properties and the scaling law for strength form a complete constitutive relation for the degrading polymers. It is shown that the constitutive law can capture the trend of the experimental data in the literature for a range of biodegradable polymers fairly well. Copyright © 2016 Elsevier Ltd. All rights reserved.

A model for ionic polymer metal composites as sensors

NASA Astrophysics Data System (ADS)

Bonomo, C.; Fortuna, L.; Giannone, P.; Graziani, S.; Strazzeri, S.

2006-06-01

This paper introduces a comprehensive model of sensors based on ionic polymer metal composites (IPMCs) working in air. Significant quantities ruling the sensing properties of IPMC-based sensors are taken into account and the dynamics of the sensors are modelled. A large amount of experimental evidence is given for the excellent agreement between estimations obtained using the proposed model and the observed signals. Furthermore, the effect of sensor scaling is investigated, giving interesting support to the activities involved in the design of sensing devices based on these novel materials. We observed that the need for a wet environment is not a key issue for IPMC-based sensors to work well. This fact allows us to put IPMC-based sensors in a totally different light to the corresponding actuators, showing that sensors do not suffer from the same drawbacks.

Mean-Field Models of Structure and Dispersion of Polymer-nanoparticle Mixtures

DTIC Science & Technology

2010-07-29

out of the seminal descriptions of the wetting and dewetting of polymer melts on polymer brushes advanced by Leibler and coworkers.118,119 Explicitly...using scaling ideas and strong segregation theory calculations they delineated the regions where the matrix polymer wets or dewets the brush. In the...Explicitly, when dewetting of the melt chains is expected ( dry brush). In other words, situations involving long matrix polymers and/or densely grafted

Comparative study of bending characteristics of ionic polymer actuators containing ionic liquids for modeling actuation

NASA Astrophysics Data System (ADS)

Kikuchi, Kunitomo; Sakamoto, Takumi; Tsuchitani, Shigeki; Asaka, Kinji

2011-04-01

Ionic polymer metal composites (IPMCs) that can operate in air have recently been developed by incorporating an ionic liquid in ionic polymers. To understand transduction in these composites, it is important to determine the role of the ionic liquid in the ionic polymer (Nafion®), to identify the counter cation, and to investigate the interaction of IPMCs with water vapor in the air. We used Fourier-transform infrared spectroscopy to analyze three Nafion® membranes, which were soaked in mixtures of water and an ionic liquid (1-ethyl-3-methyl-imidazolium tetrafluoroborate (EMIBF4), 1-buthyl-3-methyl-imidazolium tetrafluoroborate (BMIBF4), and 1-buthyl-3-methyl-imidazolium hexafluorophosphate (BMIPF6)). The results demonstrate that only cations (EMI+ and BMI+) in the ionic liquids are taken into the Nafion® membranes as counter ions and that the water content of the membranes in air is less than ˜4% that of Nafion® swollen with water. Based on the experimental results, a transduction model is proposed for an IPMC with an ionic liquid. In this model, bending is caused by local swelling due to the volume effect of the bulky counter cations. This model can explain 30-50% of the experimentally observed bending curvature.

Combining first-principles and data modeling for the accurate prediction of the refractive index of organic polymers

NASA Astrophysics Data System (ADS)

Afzal, Mohammad Atif Faiz; Cheng, Chong; Hachmann, Johannes

2018-06-01

Organic materials with a high index of refraction (RI) are attracting considerable interest due to their potential application in optic and optoelectronic devices. However, most of these applications require an RI value of 1.7 or larger, while typical carbon-based polymers only exhibit values in the range of 1.3-1.5. This paper introduces an efficient computational protocol for the accurate prediction of RI values in polymers to facilitate in silico studies that can guide the discovery and design of next-generation high-RI materials. Our protocol is based on the Lorentz-Lorenz equation and is parametrized by the polarizability and number density values of a given candidate compound. In the proposed scheme, we compute the former using first-principles electronic structure theory and the latter using an approximation based on van der Waals volumes. The critical parameter in the number density approximation is the packing fraction of the bulk polymer, for which we have devised a machine learning model. We demonstrate the performance of the proposed RI protocol by testing its predictions against the experimentally known RI values of 112 optical polymers. Our approach to combine first-principles and data modeling emerges as both a successful and a highly economical path to determining the RI values for a wide range of organic polymers.

Droplet size in flow: Theoretical model and application to polymer blends

NASA Astrophysics Data System (ADS)

Fortelný, Ivan; Jůza, Josef

2017-05-01

The paper is focused on prediction of the average droplet radius, R, in flowing polymer blends where the droplet size is determined by dynamic equilibrium between the droplet breakup and coalescence. Expressions for the droplet breakup frequency in systems with low and high contents of the dispersed phase are derived using available theoretical and experimental results for model blends. Dependences of the coalescence probability, Pc, on system parameters, following from recent theories, is considered and approximate equation for Pc in a system with a low polydispersity in the droplet size is proposed. Equations for R in systems with low and high contents of the dispersed phase are derived. Combination of these equations predicts realistic dependence of R on the volume fraction of dispersed droplets, φ. Theoretical prediction of the ratio of R to the critical droplet radius at breakup agrees fairly well with experimental values for steadily mixed polymer blends.

Modeling FtsZ ring formation in the bacterial cell-anisotropic aggregation via mutual interactions of polymer rods.

PubMed

Fischer-Friedrich, Elisabeth; Gov, Nir

2011-04-01

The cytoskeletal protein FtsZ polymerizes to a ring structure (Z ring) at the inner cytoplasmic membrane that marks the future division site and scaffolds the division machinery in many bacterial species. FtsZ is known to polymerize in the presence of GTP into single-stranded protofilaments. In vivo, FtsZ polymers become associated with the cytoplasmic membrane via interaction with the membrane-binding proteins FtsA and ZipA. The FtsZ ring structure is highly dynamic and undergoes constantly polymerization and depolymerization processes and exchange with the cytoplasmic pool. In this theoretical study, we consider a scenario of Z ring self-organization via self-enhanced attachment of FtsZ polymers due to end-to-end interactions and lateral interactions of FtsZ polymers on the membrane. With the assumption of exclusively circumferential polymer orientations, we derive coarse-grained equations for the dynamics of the pool of cytoplasmic and membrane-bound FtsZ. To capture stochastic effects expected in the system due to low particle numbers, we simulate our computational model using a Gillespie-type algorithm. We obtain ring- and arc-shaped aggregations of FtsZ polymers on the membrane as a function of monomer numbers in the cell. In particular, our model predicts the number of FtsZ rings forming in the cell as a function of cell geometry and FtsZ concentration. We also calculate the time of FtsZ ring localization to the midplane in the presence of Min oscillations. Finally, we demonstrate that the assumptions and results of our model are confirmed by 3D reconstructions of fluorescently-labeled FtsZ structures in E. coli that we obtained.

Diamond-like-carbon nanoparticle production and agglomeration following UV multi-photon excitation of static naphthalene/helium gas mixtures

NASA Astrophysics Data System (ADS)

Walsh, A. J.; Tielens, A. G. G. M.; Ruth, A. A.

2016-07-01

We report the formation of nanoparticles with significant diamond character after UV multi-photon laser excitation of gaseous naphthalene, buffered in static helium gas, at room temperature. The nanoparticles are identified in situ by their absorption and scattering spectra between 400 and 850 nm, which are modeled using Mie theory. Comparisons of the particles' spectroscopic and optical properties with those of carbonaceous materials indicate a sp3/sp2 hybridization ratio of 8:1 of the particles formed. The particle extinction in the closed static (unstirred) gas-phase system exhibits a complex and quasi-oscillatory time dependence for the duration of up to several hours with periods ranging from seconds to many minutes. The extinction dynamics of the system is based on a combination of transport features and particle interaction, predominantly agglomeration. The relatively long period of agglomeration allows for a unique analysis of the agglomeration process of diamond-like carbon nanoparticles in situ.

Effect of particle size, polydispersity and polymer degradation on progesterone release from PLGA microparticles: Experimental and mathematical modeling.

PubMed

Busatto, Carlos; Pesoa, Juan; Helbling, Ignacio; Luna, Julio; Estenoz, Diana

2018-01-30

Poly(lactic-co-glycolic acid) (PLGA) microparticles containing progesterone were prepared by the solvent extraction/evaporation and microfluidic techniques. Microparticles were characterized by their size distribution, encapsulation efficiency, morphology and thermal properties. The effect of particle size, polydispersity and polymer degradation on the in vitro release of the hormone was studied. A triphasic release profile was observed for larger microparticles, while smaller microspheres showed a biphasic release profile. This behavior is related to the fact that complete drug release was achieved in a few days for smaller microparticles, during which polymer degradation effects are still negligible. A mathematical model was developed that predicts the progesterone release profiles from different-sized PLGA microspheres. The model takes into account both the dissolution and diffusion of the drug in the polymeric matrix as well as the autocatalytic effect of polymer degradation. The model was adjusted and validated with novel experimental data. Simulation results are in very good agreement with experimental results. Copyright © 2017 Elsevier B.V. All rights reserved.

Flory-type theories of polymer chains under different external stimuli

NASA Astrophysics Data System (ADS)

Budkov, Yu A.; Kiselev, M. G.

2018-01-01

In this Review, we present a critical analysis of various applications of the Flory-type theories to a theoretical description of the conformational behavior of single polymer chains in dilute polymer solutions under a few external stimuli. Different theoretical models of flexible polymer chains in the supercritical fluid are discussed and analysed. Different points of view on the conformational behavior of the polymer chain near the liquid-gas transition critical point of the solvent are presented. A theoretical description of the co-solvent-induced coil-globule transitions within the implicit-solvent-explicit-co-solvent models is discussed. Several explicit-solvent-explicit-co-solvent theoretical models of the coil-to-globule-to-coil transition of the polymer chain in a mixture of good solvents (co-nonsolvency) are analysed and compared with each other. Finally, a new theoretical model of the conformational behavior of the dielectric polymer chain under the external constant electric field in the dilute polymer solution with an explicit account for the many-body dipole correlations is discussed. The polymer chain collapse induced by many-body dipole correlations of monomers in the context of statistical thermodynamics of dielectric polymers is analysed.

Generalized theory of semiflexible polymers.

PubMed

Wiggins, Paul A; Nelson, Philip C

2006-03-01

DNA bending on length scales shorter than a persistence length plays an integral role in the translation of genetic information from DNA to cellular function. Quantitative experimental studies of these biological systems have led to a renewed interest in the polymer mechanics relevant for describing the conformational free energy of DNA bending induced by protein-DNA complexes. Recent experimental results from DNA cyclization studies have cast doubt on the applicability of the canonical semiflexible polymer theory, the wormlike chain (WLC) model, to DNA bending on biologically relevant length scales. This paper develops a theory of the chain statistics of a class of generalized semiflexible polymer models. Our focus is on the theoretical development of these models and the calculation of experimental observables. To illustrate our methods, we focus on a specific, illustrative model of DNA bending. We show that the WLC model generically describes the long-length-scale chain statistics of semiflexible polymers, as predicted by renormalization group arguments. In particular, we show that either the WLC or our present model adequately describes force-extension, solution scattering, and long-contour-length cyclization experiments, regardless of the details of DNA bend elasticity. In contrast, experiments sensitive to short-length-scale chain behavior can in principle reveal dramatic departures from the linear elastic behavior assumed in the WLC model. We demonstrate this explicitly by showing that our toy model can reproduce the anomalously large short-contour-length cyclization factors recently measured by Cloutier and Widom. Finally, we discuss the applicability of these models to DNA chain statistics in the context of future experiments.

Spatiotemporal evolution of hairpin eddies, Reynolds stress, and polymer torque in polymer drag-reduced turbulent channel flows.

PubMed

Kim, Kyoungyoun; Sureshkumar, Radhakrishna

2013-06-01

To study the influence of dynamic interactions between turbulent vortical structures and polymer stress on turbulent friction drag reduction, a series of simulations of channel flow is performed. We obtain self-consistent evolution of an initial eddy in the presence of polymer stresses by utilizing the finitely extensible nonlinear elastic-Peterlin (FENE-P) model. The initial eddy is extracted by the conditional averages for the second quadrant event from fully turbulent Newtonian flow, and the initial polymer conformation fields are given by the solutions of the FENE-P model equations corresponding to the mean shear flow in the Newtonian case. At a relatively low Weissenberg number We(τ) (=50), defined as the ratio of the polymer relaxation time to the wall time scale, the generation of new vortices is inhibited by polymer-induced countertorques. Thus fewer vortices are generated in the buffer layer. However, the head of the primary hairpin is unaffected by the polymer stress. At larger We(τ) values (≥100), the hairpin head becomes weaker and vortex autogeneration and Reynolds stress growth are almost entirely suppressed. The temporal evolution of the vortex strength and polymer torque magnitude reveals that polymer extension by the vortical motion results in a polymer torque that increases in magnitude with time until a maximum value is reached over a time scale comparable to the polymer relaxation time. The polymer torque retards the vortical motion and Reynolds stress production, which in turn weakens flow-induced chain extension and torque itself. An analysis of the vortex time scales reveals that with increasing We(τ), vortical motions associated with a broader range of time scales are affected by the polymer stress. This is qualitatively consistent with Lumley's time criterion for the onset of drag reduction.

Transient shear banding in the nematic dumbbell model of liquid crystalline polymers

NASA Astrophysics Data System (ADS)

Adams, J. M.; Corbett, D.

2018-05-01

In the shear flow of liquid crystalline polymers (LCPs) the nematic director orientation can align with the flow direction for some materials but continuously tumble in others. The nematic dumbbell (ND) model was originally developed to describe the rheology of flow-aligning semiflexible LCPs, and flow-aligning LCPs are the focus in this paper. In the shear flow of monodomain LCPs, it is usually assumed that the spatial distribution of the velocity is uniform. This is in contrast to polymer solutions, where highly nonuniform spatial velocity profiles have been observed in experiments. We analyze the ND model, with an additional gradient term in the constitutive model, using a linear stability analysis. We investigate the separate cases of constant applied shear stress and constant applied shear rate. We find that the ND model has a transient flow instability to the formation of a spatially inhomogeneous flow velocity for certain starting orientations of the director. We calculate the spatially resolved flow profile in both constant applied stress and constant applied shear rate in start up from rest, using a model with one spatial dimension to illustrate the flow behavior of the fluid. For low shear rates flow reversal can be seen as the director realigns with the flow direction, whereas for high shear rates the director reorientation occurs simultaneously across the gap. Experimentally, this inhomogeneous flow is predicted to be observed in flow reversal experiments in LCPs.

Characterization of Tantalum Polymer Capacitors

NASA Technical Reports Server (NTRS)

Spence, Penelope

2012-01-01

Overview Reviewed data Caution must be taken when accelerating test conditions Data not useful to establish an acceleration model Introduction of new failure mechanism skewing results Evidence of Anti-Wear-Out De-doping of polymer Decreased capacitance Increased ESR Not dielectric breakdown Needs further investigation Further investigation into tantalum polymer capacitor technology Promising acceleration model for Manufacturer A Possibility for use in high-reliability space applications with suitable voltage derating.

Zero-point fluctuations in naphthalene and their effect on charge transport parameters.

PubMed

Kwiatkowski, Joe J; Frost, Jarvist M; Kirkpatrick, James; Nelson, Jenny

2008-09-25

We calculate the effect of vibronic coupling on the charge transport parameters in crystalline naphthalene, between 0 and 400 K. We find that nuclear fluctuations can cause large changes in both the energy of a charge on a molecule and on the electronic coupling between molecules. As a result, nuclear fluctuations cause wide distributions of both energies and couplings. We show that these distributions have a small temperature dependence and that, even at high temperatures, vibronic coupling is dominated by the effect of zero-point fluctuations. Because of the importance of zero-point fluctuations, we find that the distributions of energies and couplings have substantial width, even at 0 K. Furthermore, vibronic coupling with high energy modes may be significant, even though these modes are never thermally activated. Our results have implications for the temperature dependence of charge mobilities in organic semiconductors.

Computer-aided design of polymers and composites

NASA Technical Reports Server (NTRS)

Kaelble, D. H.

1985-01-01

This book on computer-aided design of polymers and composites introduces and discusses the subject from the viewpoint of atomic and molecular models. Thus, the origins of stiffness, strength, extensibility, and fracture toughness in composite materials can be analyzed directly in terms of chemical composition and molecular structure. Aspects of polymer composite reliability are considered along with characterization techniques for composite reliability, relations between atomic and molecular properties, computer aided design and manufacture, polymer CAD/CAM models, and composite CAD/CAM models. Attention is given to multiphase structural adhesives, fibrous composite reliability, metal joint reliability, polymer physical states and transitions, chemical quality assurance, processability testing, cure monitoring and management, nondestructive evaluation (NDE), surface NDE, elementary properties, ionic-covalent bonding, molecular analysis, acid-base interactions, the manufacturing science, and peel mechanics.

[Effects of smoking on the concentrations of urinary 10 metabolites of polycyclic aromatic hydrocarbons in coke oven workers].

PubMed

He, Yun-feng; Zhang, Wang-zhen; Kuang, Dan; Deng, Hua-xin; Li, Xiao-hai; Lin, Da-feng; Deng, Qi-fei; Huang, Kun; Wu, Tang-chun

2012-12-01

To explore the effects of smoking on urinary 10 metabolites of polycyclic aromatic hydrocarbons (PAHs) in the coke oven workers. Occupational health examination was performed on 1401 coke oven workers in one coking plant, their urine were collected respectively. The concentrations of the ten monohydroxy polycyclic aromatic hydrocarbons in urine were detected by gas chromatography/mass spectrometry. The 1401 workers were divided into four groups, namely control, adjunct workplaces, bottom and side, top group according to their workplaces and the different concentrations of PAHs in the environment. The concentrations of the ten monohydroxy polycyclic aromatic hydrocarbons between smokers and nonsmokers in each workplace group were compared using analysis of covariance, respectively. The levels of concentrations of the sixteen polycyclic aromatic hydrocarbons we detected at control were significantly higher than those at other areas (P < 0.05). Comparing the ten monohydroxy polycyclic aromatic hydrocarbons levels between smokers and nonsmokers, the levels of 1-hydroxynaphthalene and 2-hydroxynaphthalene among smokers were higher than nonsmokers with statistically significance in control, adjunct workplaces, bottom and side and top groups (P < 0.05). However, the levels of 1-hydroxypyrene had no statistically significant differences between the four areas. Urinary 1-hydroxynaphthalene and 2-hydroxynaphthalene may be used as biomarkers for the impact of smoking on monohydroxy polycyclic aromatic hydrocarbons in the coke oven workers.